Role of intestinal microbiota in colon cancer prevention

Loredana Baffoni; Francesca Gaggìa; Diana Gioia; Bruno Biavati

doi:10.1007/s13213-011-0306-6

Role of intestinal microbiota in colon cancer prevention

Baffoni, Loredana; Gaggìa, Francesca; Gioia, Diana; Biavati, Bruno 2011-07-20 00:00:00 Ann Microbiol (2012) 62:15–30 DOI 10.1007/s13213-011-0306-6 REVIEW ARTICLE Loredana Baffoni & Francesca Gaggìa & Diana Di Gioia & Bruno Biavati Received: 18 February 2011 /Accepted: 21 June 2011 /Published online: 20 July 2011 Springer-Verlag and the University of Milan 2011 Abstract Environmental and hereditary factors, together Intestinal homeostasis relies on the equilibrium between with lifestyle, are important factors in colon cancer absorption (nutrients, ions), secretion (ions, IgA), and the development. Considering the increasing incidence of this barrier capacity of the digestive epithelium towards disease, especially in the developed western world, the last pathogens and macromolecules. These functions are con- decade has seen much attention directed towards under- trolled through multiple interactions with the endocrine, standing possible prevention strategies. Efforts to study the neurocrine, stromal and immune cells and with the resident intestinal microbiota and its interaction with the host have bacterial microbiota that regulates epithelial functions. The underlined that disbiosis in colonic bacterial composition is development and maintenance of a healthy microbiota is a risk factor for colon cancer. Modulation of the composi- extremely important for the correct maturation of the gut tion of intestinal microbiota through the use of probiotic, associated lymphoid tissue (GALT) and the intestinal prebiotic and synbiotic products could therefore represent a mucosa (Macpherson and Harris 2002; Schiffrin and Blum strategy for prevention of cancer development. The mech- 2002; McCracken and Lorenz 2001). anisms underlying the probiotic-prebiotic anticarcinogenic The human microbiota is a complex ecosystem harbour- effect involve a combination of events: e.g. binding of ing more than 1,000 species (Qin et al. 2010) although its mutagens, suppression of bacteria that convert pro- true size and diversity remain largely unknown (Marchesi carcinogens into carcinogens, immune system stimulation, 2010; Hattori and Taylor 2009; Ley et al. 2006). Microbial and a reduction in the level of certain intestinal bacterial colonisation begins immediately after birth with a succes- enzymes that promote carcinogen formation. sion of different species colonising each gastrointestinal (GI) site until an equilibrium is reached (Guarner and . . Keywords Colon cancer Mechanism of prevention Malagelada 2003;O’Hara and Shanahan 2006). Because . . Probiotic Prebiotic Synbiotic intestinal motility is slow, and oxidation-reduction poten- tials are very low, the large intestine is undoubtedly the richest colonisation site in the human body, harbouring a 10 11 Introduction great number of bacteria (10 –10 cfu/g intestinal content) (Hao and Lee 2004), constituted mainly by anaerobes or The intestine constitutes the largest site of interaction facultative anaerobes, including Bacteroides, Peptostrepto- between an individual and the surrounding environment. coccus, Eubacterium, Bifidobacterium, Ruminococcus, Fusobacterium, Clostridium, Lactobacillus, Enterococcus, Enterobacter, Escherichia coli. The colonic microbiota influences a variety of intestinal : : : L. Baffoni (*) F. Gaggìa D. Di Gioia B. Biavati functions and plays a key role in nutrition, in maintaining Department of Agroenvironmental Sciences and Technologies, the integrity of the epithelial barrier, and in the development University of Bologna, of mucosal immunity (Shanahan 2002). Unabsorbed dietary viale Fanin 42, sugars, such as lactose, alcohols and undigested polysac- 40127 Bologna, Italy charides are salvaged by bacterial enzymes, and fermented e-mail: loredana.baffoni@unibo.it 16 Ann Microbiol (2012) 62:15–30 into short-chain fatty acids (SCFAs) that are used as an Early detection and surgery have significantly reduced energy source by the colonic mucosa. SCFAs promote both mortality and morbidity in patients affected by the growth of intestinal epithelial cells and control their colorectal cancer, but survival after surgical treatment for proliferation and differentiation. Moreover, enteric bac- advanced tumour has not seen significant improvements in teria produce valuable vitamins, such as folate, vitamins recent years. Hence, prevention of the development of of B group (B1, B2, B6, B12) and vitamin K colorectal cancer appears to be a more rational and effective (Ballongue 2004). The relationship between the host strategy. The multistep nature of colorectal cancer, together immune system and the indigenous microbiota is impor- with the concept of carcinogenesis (i.e. the phenomenon by tant in protecting the host from pathogen colonisation. In which independent premalignant foci may progress concur- this regard, intestinal bacteria produce a variety of rently and at different rates to give rise to multiple primary substances, ranging from relatively nonspecific acids, tumours), make the colon a peculiarly suitable target organ fatty acids and peroxides, to highly specific bacteriocins for any given chemoprevention study. Indeed, chemo- that can inhibit or kill potentially pathogenic bacteria prevention of colorectal cancer in humans has been the (Servin 2004). focus of a number of studies where fibre, vitamins, calcium, low-fat diet, and non-steroidal anti-inflammatory drugs have all been shown to affect the incidence of this disease. Importance of prevention in colon cancer development Approximately 70% of colorectal cancer is associated with environmental factors, mainly diet (Saikali et al. 2004). Cancer is a combination of various metabolic and physio- Thus, much attention has focused on decreasing cancer risk logic disturbances in the cell that are directly or indirectly through changes in dietary habits, consumption of pro- related to the influence of genetic makeup. Generally, all biotics and increasing intake of dietary fibres (prebiotics). It cancers involve the malfunction of genes that control cell has been reported that ingestion of probiotics, prebiotics, or growth and division. The process by which cancer develops a combination of both (synbiotics) plays an important role is called carcinogenesis. Generally, the carcinogenesis in the prevention of colorectal cancer, and represents a process starts when DNA is damaged by chemicals or novel new therapeutic option (Jain et al. 2009; Le Leu et al. radiation (carcinogen). Viruses are also potent inducers of 2010; Choi et al. 2006). cancer, and usually induce carcinogenesis by introducing new DNA sequences. Normal cells have DNA repair machinery, so that, most of the time, when DNA is Probiotic, prebiotic and synbiotic: a definition damaged the cell is able to repair it. Genetic instability Many definitions have been proposed for the term probiotic. provides a mechanism through which normal cells can accumulate sufficient mutations to become malignant. As originally defined by Fuller, a probiotic is “alive microbial However, cells possess important mechanisms to combat feed supplement which beneficially affects the host health by genomic instability, which is driven by the loss of cell-cycle improving its intestinal microbial balance” (Fuller 1989). The checkpoints, persistent DNA damage or telomere dysfunc- most recent definition provided by FAO-WHO is: “live tion. Central to this mechanism is the tumour-suppressor microorganisms which, when administered in adequate protein p53. The p53 protein is important in transducing amounts, confer a health benefit on the host” (FAO/WHO diverse signals such as a range of stresses (i.e. DNA 2002). Probiotics belong mainly to the genera Lactobacillus damage, hypoxia or proliferative signals) into tumour- and Bifidobacterium (Macfarlane and Cummings 1999; suppressive apoptotic or growth-arresting responses; this Biavati et al. 2000; Biavati and Mattarelli 2006). Potential implies that there is strong selection for tumour cells to lose health benefits deriving from probiotics may vary depending p53 function (Brown and Attardi 2005; Evan and Vousden on the type of probiotic consumed. Probiotic species that can 2001). The exact mechanisms whereby the development of be used in food or pharmaceutical preparations need to have cancer is mediated through mutations are still obscure; Qualified Presumption of Safety (QPS) status. The QPS since carcinogenesis is a multistep process, just how many concept provides a generic assessment system for use within mutations in DNA are required for the development of the the European Food Safety Authority (EFSA) that in principle complete carcinogenesis process remains unknown. As can be applied to all requests received for the safety many as ten distinct mutations may have to accumulate in assessments of microorganisms deliberately introduced into a cell before the cell becomes cancerous (Jain et al. 2009). the food chain. In essence, this proposed that a safety The increasing prevalence of human colorectal cancer assessment of a defined taxonomic group (e.g. genus or is attracting the attention of health professionals and group of related species) could be made based on four researchers seeking more efficacious therapeutic and pillars: establishing identity, body of knowledge, possible prevention strategies. pathogenicity and end use. If the taxonomic group did not Ann Microbiol (2012) 62:15–30 17 raise safety concerns or, if safety concerns existed but could on the other hand applies the Generally Recognized As Safe be excluded through targeted characterisation studies, QPS (GRAS) concept. Both QPS and GRAS share the same core status could be granted. QPS granted microorganisms are values; however, considering the different social and regula- listed in Table 1 (EFSA 2008). The United States Food and tory climate present in Europe, issues of importance to Drug Administration (FDA)—the US equivalent of EFSA— Europe would not necessary influence a GRAS listing. Table 1 List of microorganisms granted Qualified Presumption of Safety (QPS) status (EFSA 2008) (kindly provided by Gaggìa et al. 2010) Gram-positive non-sporulating bacteria Bifidobacterium adolescentis Bifidobacterium animalis Bifidobacterium breve Bifidobacterium bifidum Bifidobacterium longum Corynebacterium glutamicum Lactobacillus acidophilus Lactobacillus delbrueckii Lactobacillus panis Lactobacillus amylolyticus Lactobacillus farciminis Lactobacillus paracasei Lactobacillus amylovorus Lactobacillus fermentum Lactobacillus paraplantarum Lactobacillus alimentarius Lactobacillus gallinarum Lactobacillus pentosus Lactobacillus aviaries Lactobacillus gasseri Lactobacillus plantarum Lactobacillus brevis Lactobacillus helveticus Lactobacillus pontis Lactobacillus buchneri Lactobacillus hilgardii Lactobacillus reuteri Lactobacillus casei Lactobacillus johnsonii Lactobacillus rhamnosus Lactobacillus coryniformis Lactobacillus kefiranofaciens Lactobacillus sakei Lactobacillus crispatus Lactobacillus kefiri Lactobacillus salivarius Lactobacillus curvatus Lactobacillus mucosae Lactobacillus sanfranciscensis Lactococcus lactis Leuconostoc citreum Leuconostoc lactis Leuconostoc mesenteroides Pediococcus acidilactici Pediococcus dextrinicus Pediococcus pentosaceus Propionibacterium freudenreichii Streptococcus thermophilus Gram-positive sporulating bacteria Bacillus amyloliquefaciens Bacillus atrophaeus Bacillus lentus Bacillus pumilus Bacillus clausii Bacillus licheniformis Bacillus subtilis Bacillus coagulans Bacillus megaterium Bacillus vallismortis Bacillus fusiformis Bacillus mojavensis Geobacillus stearothermophillus Yeast Debaryomyces hansenii Hanseniaspora uvarum Kluyveromyces lactis Kluyveromyces marxianus Pichia angusta Pichia jadinii Pichia anomala Pichia pastoris Saccharomyces bayanus Saccharomyces pastorianus (synonym Saccharomyces carlsbergensis) Saccharomyces cerevisiae Schizosaccharomyces pombe Xanthophyllomyces dendrorhous 18 Ann Microbiol (2012) 62:15–30 Prebiotic compounds are defined as “non-digestible food Ochratoxin A (OTA), a toxin produced by Aspergillus ingredients that beneficially affect the host by selectively ochraceus and Penicillium verrucosum, is one of the most stimulating the growth and/or activity of one or a limited abundant food-contaminating mycotoxins in the world. number of bacteria in the colon” (Gibson and Roberfroid Fumonisins are a family of toxins produced by several species 1995). For a dietary substrate to be classified as a prebiotic, of Fusarium moulds, which occur mainly in maize, wheat at least three criteria are required: (1) the substrate must not and other cereals. Aflatoxins, OTA and fumonisins are be hydrolyzed or absorbed in the stomach or small considered carcinogens by the World Health Organization intestine; (2) it must be selective for beneficial commensal International Agency for Research on Cancer (IARC 1993). bacteria, such as the bifidobacteria, in the large intestine; (3) Many studies have investigated the binding of aflatoxins fermentation of the substrate should induce beneficial luminal/ to lactic acid and probiotic bacteria (Fazeli et al. 2009; systemic effects within the host (Scantlebuy-Manning and Bueno et al. 2007; Haskard et al. 2001). The binding of the Gibson 2004). Dietary modulation of the human gut micro- toxin is strain-dependent and is reversible in nature (Fazeli biota with prebiotics has been investigated for many years to et al. 2009; Haskard et al. 2001). Some researchers have improve gut microbial balance (Hord 2008; Roberfroid suggested that aflatoxin molecules bind cell wall compo- 2007; Rastall et al. 2005). nents of the bacteria (Hernandez-Mendoza et al. 2009; Synbiotics may be defined as mixtures of probiotics and Haskard et al. 2001), but cell surface hydrophobicity may prebiotics that beneficially affect the host by improving the also play an important role (Oatley et al. 2000). Lahtinen et survival and implantation of live microbial dietary supple- al. (2004) stressed that cell wall polysaccharides and ments in the gastrointestinal tract (Gibson and Roberfroid peptidoglycan may be the most important elements respon- 1995). Roberfroid (1998) suggested that a combination of sible for the binding mechanism. Some experiments also prebiotics and probiotics might be more active on the colon reveal that heat treatment of bacterial cells improves their than the individual components alone. The effectiveness of ability to remove aflatoxins AFM1 and AFB1, possibly due a synbiotic formula is, however, strictly dependent on the to the formation of Maillard reaction products between probiotic strain properties and its fermentation ability polysaccharides, peptides, and proteins (El-Nezami et al. towards the selected prebiotic compound. 2002; Pierides et al. 2000). In contrast, research by El- Nezami and coworkers (1998a) showed that heat-treated dairy strains of LAB seem to have the same ability to Mechanisms underlying cancer prevention remove AFB1 as viable bacteria, indicating that viability may not be an essential prerequisite. Polarity of the toxins The anti-carcinogenic properties of probiotic bacteria are also plays an important role in the binding mechanism. The percentage of aflatoxin removed by dairy strains of LAB probably linked to multiple activities: (1) carcinogen binding, (2) modulation of the other intestinal bacteria and bifidobacteria decreases in the order: AFB1 > AFB2 > enzymes, (3) effects on oxidative stress, (4) production of AFG1 > AFG2, which is correlated with the decreasing beneficial compounds, (5) immune modulation, and (6) polarity of these toxins and is consistent with hydrophobic apoptotic deletion. interactions, suggesting the involvement of the latter in the binding mechanism (Haskard et al. 2000). Another critical Binding/absorption of carcinogens factor, as reported by El-Nezami et al. (1998b), is the size of the bacterial population involved in aflatoxin binding; it is Studies confirm that some strains of lactic acid bacteria (LAB) estimated that a minimum of approximately 2 x 10 CFU/ml are able to bind food carcinogens (e.g. mycotoxins or is required for significant AFB1 removal. The same amount heterocyclic aromatic amines present in cooked meat and seems to be necessary for binding of OTA (Fuchs et al. fish), excluding them from the human gut and reducing 2008) by strains of Lactobacillus, Propionibacterium and thereby the rate of exposure to these highly toxic compounds. Bifidobacterium (Kabak and Dobson 2009). Aflatoxins are naturally occurring mycotoxins and are Studies also indicate that probiotic bacteria can bind among the most carcinogenic substances known, being other toxic compounds, e.g. toxic secondary bile acids metabolized by the liver to a reactive epoxide intermediate. produced by the metabolic activity of some intestinal Aflatoxin B (AFB1) is considered the most toxic and is bacteria (see next section). produced by Aspergillus flavus and Aspergillus parasiticus, which also produce aflatoxin B (AFB2). Aflatoxins G and Modulation of intestinal bacteria enzymes 2 1 G (AFG1 and AFG2) are produced by Aspergillus para- siticus. Aflatoxin M (AFM1) was discovered in the milk of In addition to the aforementioned binding mechanisms, cows fed with mouldy grain and is produced following a probiotic microorganisms could play a role in the preven- conversion process of aflatoxin B in the animal’s liver. tion of the initiation phase of carcinogenesis by decreasing 1 Ann Microbiol (2012) 62:15–30 19 exposure to activated faecal carcinogens. Animal and human bile acids are secreted into the duodenum in the form of studies with Lactobacillus and Bifidobacterium supplements conjugates, which are degraded by bacterial enzymes in show a drop in detrimental faecal enzyme concentrations the large intestine and transformed to deconjugated or such as nitroreductase, β-glucuronidase, azoreductase, 7α- secondary bile acids that are toxic. A high dietary intake dehydroxylase and urease (Kumar et al. 2010). It is well of fat and red meat results in a significantly higher known that these enzymes, which are present in some excretion of faecal secondary bile acids (Reddy et al. intestinal bacteria, are able to convert pro-carcinogen 1980; Bernstein et al. 2009) and conjugated bile acids compounds into carcinogens in the human colon. seem to enhance excretion of β-glucuronidase from, for Nitroreductases from bacteria are oxygen-insensitive and example, E. coli and C. perfringens. catalyse the reduction of nitro-compounds, producing Azo dye compounds represent a large group of chem- nitroso, hydroxylamine, and/or amino derivatives. These icals that are used extensively in the textile, pharmaceutical, nitroreductases have been studied in a number of bacteria food, and cosmetic industries. Although the commonly including enterobacteria (e.g. Escherichia coli, Salmonella used azo dyes are not mutagenic in the standard Ames plate typhimurium, Enterobacter cloacae), and exhibit varying assay, they are reduced by azoreductases from intestinal substrate specificities, being able to reduce a wide range of bacteria and, to a lesser extent, by enzymes of the cytosolic nitroaromatics such as nitrophenols, nitrobenzenes, and and microsomal fractions of the liver. Some intestinal nitrobenzoates. A large number of nitroaromatics are bacteria that contain azoreductase belong to the following present in the environment because of their use in genera: Bacteroides spp. (B. fragilis, B. thetaiotaomicron, manufacturing processes and as antimicrobial agents, and B. ovatus and B. vulgatus), Eubacterium spp. (e.g. E. they are also generated as by-products of combustion hadrum) (Rafii et al. 1990), Clostridium spp. (e.g. C. processes. Nitroaromatic compounds have caused consid- leptum, C. paraputrificum, C. clostridiiforme, C. perfrin- erable health concern because their metabolism through gens, C. sporogenes, C. septicum,and C. butyricum) reductive pathways may lead to potent genotoxic and/or (McBain and Macfarlane 1998), Butyrivibrio. Azo dye mutagenic metabolites. Thus, enzymatic reduction by compounds are linked to bladder cancer in humans and to nitroreductases gives rise to reactive intermediates that can hepatocarcinoma and nuclear anomalies in intestinal epi- undergo nucleophilic additions with DNA and other macro- thelial cells in mice. Thus, a number of azo dyes are molecules, suggesting a possible mechanism for their classified as carcinogenic (Rafii et al. 1990). cytotoxicity (Guillén et al. 2009). Some species of the 7α-Dehydroxylase is a detrimental enzyme responsible following genera encode nitroreductases: Clostridium for producing harmful secondary bile acids that exert a spp. (e.g. C. leptum, C. paraputrificum, C. clostridiiforme, cytotoxic effect towards epithelial cells. This enzyme C. perfringens, C. septicum, C. sporogenes and C. removes the 7-alpha hydroxyl group in bile acids. The butyricum), Bacteroides spp. (B. fragilis, B. thetaiotaomi- dehydroxylation of chenodeoxycholic acid leads to the cron, B. ovatus and B. vulgatus) (McBain and Macfarlane formation of lithocholic acid (litho = stone), which is 1998). poorly water-soluble and toxic to cells, producing DNA Intestinal β-glucuronidase may be involved in the breaks (Bernstein et al. 2005). Bile acids formed by development of large bowel cancer. The activity of β- synthesis in the liver are termed “primary” bile acids, glucuronidase in faecal samples or colon contents is and those made by bacteria are termed “secondary” bile increased by high fat diets. Genotoxic and carcinogenic acids (Commane et al. 2005). heterocyclic aromatic amines (HHAs), e.g. 2-amino-3- Urease is en enzyme that breaks the C–N linkage of urea methylimidazo[4,5-f]quinoline (IQ), are formed in meat to form CO ,NH and H O. Urease-producing bacteria 2 3 2 and fish during cooking. Following absorption in the upper inhabiting the GI tract are important in both their nutritional part of the gastrointestinal tract, IQ is metabolized mainly and pathological aspects because they are involved in in the liver by xenobiotic-metabolising enzymes. Among nitrogen recycling, and the resulting product, ammonia, can them, UDP-glucuronosyl transferases lead to harmless be harmful to host health. The following species of glucuronidated derivatives that are partly excreted via the anaerobes include urease-producing strains: Bacteroides bile into the digestive lumen, where they come into contact multiacidus (now: Mitsuokella multiacida), Clostridium with the resident microbiota. β-glucuronidase could con- symbiosum, Eubacterium aerofaciens (now: Collinsella tribute to IQ genotoxicity by releasing reactive intermedi- aerofaciens), Eubacterium lentum (now: Eggerthella lenta), ates from IQ glucuronides (Humblot et al. 2007). This Fusobacterium necrophorum, Fusobacterium varium, Pep- enzyme activity is reported to be present in some intestinal tococcus asaccharolyticus (now: Peptoniphilus asacchar- bacteria such as E. coli, Peptostreptococcus, Bacteroides olyticus), Peptococcus prevotii (now: Anaerococcus (e.g. B. fragilis, B. thetaiotaomicron)and C. perfringens. prevotii), and Peptostreptococcus productus (now: Blautia Faecal bile acid excretion is also increased by a fatty diet; producta) (Suzuki et al. 1979). 20 Ann Microbiol (2012) 62:15–30 Effects on oxidative stress idative activity, inhibiting linoleic acid peroxidation by 28–48% and also show the ability to scavenge the α- Oxidative stress results when the balance between the diphenyl-β-picrylhydrazyl free radical, scavenging 21– production of ROS (reactive oxygen species) overrides the 52%. The intact cells of these two intestinal bacteria antioxidant capability of the target cell. ROS may interact demonstrate a high inhibitory effect on the cytotoxicity of with and modify cellular protein, lipid, and DNA, which 4-nitroquinoline-N-oxide (4NQO, a quinoline derivative results in altered target cell function. The accumulation of and tumorigenic compound). The cytotoxicity of 4NQO is oxidative damage has been implicated in both acute and reduced by approximately one-half by L. acidophilus and chronic cell injury, including participation in the formation by almost 90% by B. longum. Nevertheless, no inhibition of of cancer (Halliwell 2007). ROS can be produced both cytoxicity is observed for intracellular cell-free extracts of endogenously and exogenously. Endogenous oxidative 10 cells of B. longum and L. acidophilus. Pediococcus stress can be the result of normal cellular metabolism and pentosaceus 16:1 and Lactobacillus plantarum 2592 pro- oxidative phosphorylation. The metabolism of substances duce antioxidants after 18 h growth corresponding to by the P450 enzyme system generates oxygen free radicals 100 μg vitamin C, Lactobacillus paracasei F19 a slightly through normal or futile cycling mechanisms (Parke and lower amount, and yet another, L. paracasei, does not exert Ioannides 1990). Exogenous sources of ROS can also any antioxidative activity, again emphasizing that these impact on the overall oxidative status of a cell. Drugs, characteristics are strain-dependent (Kruszewska et al. hormones, and other xenobiotic chemicals can produce 2002). In another study, obligatory homofermentative ROS by either direct or indirect mechanisms (Trush and lactobacilli display high antioxidant activity whereas this Kensler 1991; Halliwell 1996). Alternatively, oxidative property is highly strain-dependent among facultative and stress can also occur when a decrease in the antioxidant obligate heterofermentative lactobacilli (Annuk et al. 2003; capacity of a cell occurs. Non-enzymatic antioxidant levels Kumar et al. 2010). [vitamin E, vitamin C, glutathione (GSH), etc.] and enzymatic antioxidant levels (superoxide dismutase, GSH Production of beneficial compounds peroxidase, and catalase) in the cell can be decreased through modification in gene expression, reduced uptake in Bacterial fermentation in the colonic lumen produces a the diet, or can be overloaded in ROS production, which variety of short chain fatty acid (SCFA) metabolites (e.g. creates a net increase in the amount of oxygen free radicals acetate, butyrate, propionate) that are potential anti- present in the cell (Vuillaume 1987; Barber and Harris carcinogenic agents within the gut. Butyrate has been 1994). Several human chronic disease states (e.g. cirrhosis, implicated in cellular homeostasis of the normal colonic atherosclerosis etc.), including cancer, are associated with mucosa, and this is thought to be one of the mechanisms of oxidative stress (Valko et al. 2007). Some lactobacilli the chemoprotective effect of fibre. In vitro studies indicate possess antioxidative activity, and are able to decrease the that butyrate causes cell cycle arrest, differentiation or risk of accumulation of ROS during the ingestion of food. apoptosis in a number of transformed cell lines (Yu et al. In fact, ROS are produced during passage of nutrients 2010; Bingham et al. 2003). Femia et al. (2002) stress the through the GI tract, and the natural production of host importance of oligofructose administration, alone or to- antioxidants decreases rostrally (Blau et al. 1999, Bruce et gether with probiotic microorganisms, to increase SCFA in al., 2000). LAB are able to degrade the superoxide anion the colon, and decreases the incidence of tumour develop- and hydrogen peroxide. However, the type of superoxide ment in a rat model. dismutase (SOD) expressed in antioxidative strains has not Moreover, the production of SCFA and other organic been assessed. It remains an open question if the anti- acids by LAB and probiotics reduces intestinal pH, oxidative potency of strains is associated with their survival preventing thereby the growth of putrefactive bacteria and in stressful environments. Kullisaar et al. (2002) reported pathogens and modulating detrimental enzymes that acti- that two strains of Lactobacillus fermentum with substantial vate toxic metabolites (see section above on Modulation of antioxidative activity, express Mn-SOD (manganese-super- intestinal bacteria enzymes) (Servin 2004). A prebiotic/ oxide dismutase) and have significantly increased resistance probiotic-induced decrease in luminal colonic pH may to several ROS such as hydrogen peroxide, superoxide and function to improve mineral solubility and uptake, namely, hydroxyl radicals. LGG and LGG-fermented milk are calcium, magnesium, and iron. The availability of minerals demonstrated to be potent scavengers of superoxide anion is also enhanced through bacterial fermentation of sub- and inhibitors of lipid peroxidation reactions in vitro stances such as phytate (myoinositol hexaphosphate), (Ahotupa et al. 1996). Lin and Chang (2000) show that a which remove divalent cations. In particular, calcium is strain of Bifidobacterium longum ATCC 15708 and a strain suggested to be beneficial toward colorectal cancer, with of Lactobacillus acidophilus ATCC 4356 display antiox- increasing evidence that it inhibits proliferation and Ann Microbiol (2012) 62:15–30 21 enhances differentiation and apoptosis of mucosal cells Numerous researchers report that LAB also have the (Lamprecht and Lipkins 2003; Jain et al. 2009). ability to synthesise folate, for example industrial starter Some probiotic strains also produce molecules with bacteria Lactococcus lactis, Streptococcus thermophilus, antagonistic activity against intestinal pathogens called and Leuconostoc species and some probiotic strains (e.g. bacteriocins. Bacteriocins are a heterogeneous group of bifidobacteria, lactobacilli, propionibacteria, and Saccharo- ribosomally synthesized peptides or proteins displaying myces cerevisiae) (Iyer and Tomar 2009; Pompei et al. antimicrobial activity against other bacteria. LAB bacter- 2007). Folic acid, one of the B vitamins (B9), acts as iocins seem to be targeted primarily to other LAB, which cofactor in numerous biochemical reactions through its are likely to be the most prominent competitor in the ability to donate or accept one-carbon units. Mammals are (acidic) ecological niche in which these bacteria reside. unable to synthesise folic acid de novo and so they must However, LAB bacteriocins also show activity towards a obtain it either from the diet or from microbial breakdown number of potential Gram-positive food spoilage and/or in the gut. Folate deficiency induces cytogenetic damage pathogenic bacteria, for example towards Listeria. LAB are and mutations both in vivo and in vitro, with increases in GRAS and so are their bacteriocins, which do not affect DNA strand breakage, chromosomal aberrations and micro- humans or other eukaryotes. Bacteriocins are thus receiving nuclei formation (Duthie 1999). A number of reviews have great attention, since applications as ‘natural’ food preser- focussed on the health benefits associated with increased vatives, and maybe even as antibiotics, may be envisaged. folate intake, and many countries possess mandatory folate Since about 1990, this field has grown dramatically and this enrichment programs. Lately, a number of studies have has led to the discovery and characterisation of a large shown that high intakes of chemically synthesized folic number of bacteriocins (García et al. 2010; De Vuyst and acid, but not natural folates, can cause adverse effects in Leroy 2007). some individuals, such as the masking of the haematolog- Conjugated linoleic acids (CLA) are a family of ical manifestations of vitamin B12 deficiency, leukaemia, positional and geometric isomers of linoleic acid that have arthritis, bowel cancer, and ectopic pregnancies. Fermented been associated with several health benefits. Different milk products are reported to contain high amounts of folate bacteria have been identified as capable of synthesizing produced by food-grade bacteria, primarily LAB. The focus CLA. These include both probiotic strains and dairy starter has therefore shifted toward natural folate, i.e. folate cultures as well as strains of human intestinal origin (Mills produced by LAB, and levels of folate present in foods et al. 2009; Alonso et al. 2003; Barrett et al. 2007; Coakley fermented by, or containing, these valuable microorganisms. et al. 2006; Ewaschuk et al. 2006, Coakley et al. 2003). The proper selection and use of folate-producing micro- Several works report the ability of Bifidobacterium spp. organisms is an interesting strategy to increase “natural” folate levels in foods (Iyer and Tomar 2009). to convert LA into CLA (Van Nieuwenhove et al. 2007; Barrett et al. 2007; Ewaschuk et al. 2006; Coakley et al. Dietary flavonoids, a class of semi-essential food 2009; Rodríguez-Alcalá et al. 2011). B. breve is considered components, have long been believed to exert protective the most efficient CLA-producing species, with conversion effects against many diseases, in particular cardiovascular rates up to 65% following 48 h fermentation (Coakley et al. disease and cancer. This has been well supported by myriad 2003, 2009). However, some strains of B. breve display a studies examining potential sites and modes of action. low conversion rate (Barrett et al. 2007), thus suggesting a There has been a proliferation of mechanistic studies, strain-specific behaviour. B. breve and B. longum from concerning mainly effects on cell signalling pathways. human faecal samples demonstrate conversion rates of up However, these studies are focused entirely on the to 75% following 48 h fermentation of linoleic acid to c9, flavonoid aglycones, not the glycosides—the flavonoid t11 CLA (Barrett et al. 2007). The dairy starters Lacto- forms present in the human diet. Studies have confirmed coccus lactis and Streptococcus thermophilus also exhibit that glycoside hydrolysis is necessary prior to absorption CLA-producing activity (Lin et al. 1999)aswellasthe (Piskula 2000), and that this is accomplished by the β- strain Pediococcus acidilactici (Kishino et al. 2002). The glucosidase enzyme. This enzyme is produced by different isomers cis-9, trans-11 (c9, t11) and trans-10, cis-12 (t10, strains of probiotic bacteria and this could be an advantage c12), have demonstrated exceptional abilities in vitro, and since it may help the release of flavonoids in the large in some cases in vivo, to prevent various types of cancer bowel (Kumar et al. 2010; Marotti et al. 2007). (Belury 2002; Bhattacharya et al. 2006;Kelleyet al. 2007), hypertension, atherosclerosis, obesity, and diabetes, Immune system stimulation as well as an ability to improve immune function, bone formation-promoting properties and to reduce total body The influence of the resident microbiota on mucosal fat composition (Bhattacharya et al. 2006; Nagao and immune function and gut health has become an area of scientific and clinical importance (Fuller 1991; Cebra 1999; Yanagita 2005). 22 Ann Microbiol (2012) 62:15–30 Lee 2009). There is an active dialogue between the switching in human B cells (He et al. 2007). The IgA B commensal microbiota and the host mucosal immune cells induced in Peyer’s patches circulate through the system (Macpherson and Harris 2002). This cross-talk mesenteric lymphatic nodes to enter the blood via the elicits different host responses to commensal and patho- thoracic duct and return to the intestinal mucosa, repopulat- genic bacteria. The healthy host is able to elicit a good ing distant mucosal sites such as the bronchus. Some mucosal immune response against luminal antigens and to probiotic microorganisms are also able to increase the IgA maintain a “physiological state of inflammation” in the gut, cycle, in a dose-dependent manner (Villena et al. 2008; but is also able to face up to invading commensal Perdigon et al. 1999). T-independent IgA induction is also organisms and pathogens. In the healthy host, penetration demonstrated; cytokines, including transforming growth of the commensal bacteria is usually prevented by the factor β (TGF- β), interleukin-4 (IL-4), and IL-2, IL-6, barrier afforded by the intestinal epithelium and the and IL-10, work in a synergistic way with immune cells immune cells associated with the mucosa, which are highly other than T cells and can promote the switch from IgM to adapted to the presence of the normal microbiota. The IgA expression (He et al. 2007). Stimulation with probiotic functioning of the gut mucosal immune system requires a bacteria induces signals on epithelial and immune cells that complex network of signals, with multiple interactions evoke different patterns of cytokines in the intestine between commensals, foreign antigens and eukaryotic cells. (Perdigón et al. 2002;O’Flaherty et al. 2010), depending These include epithelial cells, macrophages, dendritic cells, on thedoseandthestrainadministered. Maldonado and cells belonging to the non-specific barriers: mucus- Galdeano et al. (2007), analysing the profile of cytokines producing cells such as goblet cells, and Paneth cells, induced by some LAB, observe that the most remarkable which secrete antimicrobial peptides (Rook and Brunet effect for all the probiotic strains tested is the increase in 2005). Three different routes exist for the uptake of luminal tumour necrosis factor-alpha (TNF-α), gamma-interferon antigens: dendritic cells, specialized M cells from the (IFN-γ) and of the regulatory cytokine IL-10. This effect is Peyer’s patches, and individual M cells found in the villous obtained without increasing the inflammatory response. epithelium (Mowat 2003;Neutraetal. 1996). The Induction of TNF-α by probiotic bacteria would be anatomical location of the immune cells from the innate necessary to initiate cross-talk between the immune cells response (macrophages and dendritic cells), and the way in associated with the lamina propria and the intestinal which these cells acquire antigens, are crucial in determining epithelial cells, while IFN- γ would play a physiological the nature of the subsequent responses. In the gut immune role. It has been demonstrated that this cytokine is response induced by commensal bacteria, the antigen necessary for the maturation of some immune cells, such presentation from the luminal microbiota leads to the as dendritic cells, and also controls their cellular prolifer- generation of large quantities of local immunoglobulin A ation at the intestinal level (Rumbo et al. 2004). It could be (IgA) without induction of systemic immunity (Macpherson postulated that probiotics (as whole cells or as antigenic and Slack 2007). fragments) interact with the M cells in Peyer’s patches, with In this complex cross-talk between commensal micro- gut epithelial cells, and with the associated immune cells. biota and the intestinal immune system, how can probiotics Following interaction with these cells, the release of affect gut mucosal immunity? It is obvious that these non- cytokines is induced to up- or down-regulate the immune pathogenic bacteria must interact with the epithelial cells response. This may depend if the induction occurs in a and with the immune cells associated with the gut in order physiological state or during pathological processes such as to trigger the network of immune signals. The increase in allergy (Pessi et al. 2000; Özdemir 2010), inflammatory the number of IgA-producing cells is the most remarkable bowel disease (Sartor 2004), or colon cancer (Rafter et al. property induced by probiotic microorganisms or by milk 2007; Takagi et al. 2001; Ewaschuk et al. 2006; Marotta et fermented with LAB (Park et al. 2002; LeBlanc et al. al. 2003), in order to maintain or try to re-establish 2002). IgAs play a critical role in mucosal immunity. In its intestinal homeostasis. Regarding this point, Maldonado secretory form, IgA is the main immunoglobulin found in Galdeano et al. (2007) suggest that, under physiological mucous secretions, including tears, saliva, colostrum and conditions, probiotic bacteria can act as mucosal and secretions from the genito-urinary tract, gastrointestinal systemic adjuvants. tract, prostate and respiratory epithelium. Within the two Under pathological states, such as colon cancer or IgA subclasses (IgA and IgA ) in humans, IgA is intestinal chronic inflammations, probiotics may inhibit 1 2 1 produced preferentially in nasal and bronchial mucosa, disease via modulation of the mucosal and systemic and IgA is produced predominately in the gut. IgA is immune response and by reduction of the inflammatory 2 2 more resistant to pathogen proteases and is present at the response to host microbiota. It has been shown that highest levels in the distal intestine, which has the heaviest intestinal inflammation is linked to the development of colorectal cancer (de Visser et al. 2006); for this purpose, bacterial load. Commensal bacteria promote IgA class 2 Ann Microbiol (2012) 62:15–30 23 some studies evidence the importance of probiotic or gens (Brown and Attardi 2005). Up-regulation or facilita- synbiotic supplementation since an increase in the produc- tion of apoptosis during initiation events might increase the tion of IL-10 (an anti-inflammatory cytokine) has been elimination of mutated cells that might otherwise progress observed (Pessi et al. 2000; Di Giacinto et al. 2005; Madsen to malignancy. Such an effect might be one of the et al. 2001). Intestinal inflammation may also result from mechanisms by which prebiotics and/or probiotics act to exposure to toxic factors such as asbestos or smoke, as well protect against colorectal cancer. Le Leu et al. (2005) as from ongoing chemical or physical irritation [acid-reflux registered a significant apoptotic response to a genotoxic disease, exposure to ultraviolet (UV) light]. Mutation and/ carcinogen in the distal colon of rats using a synbiotic or genetic polymorphism in crucial genes that regulate combination of resistant starch and Bifidobacterium ani- cytokine function, metabolism and leukocyte survival have malis subsp. lactis. A possible mechanism by which also been implicated as aetiological factors in chronic probiotic bacteria may induce apoptotic deletion could be inflammation. During acute inflammation, innate immune through their immunomodulating properties. Cytokines cells form the first line of immune defence and regulate such as TNF-α are capable of inducing apoptosis. Although activation of adaptive immune responses. Conversely, during cytokine levels were not measured by Le Leu et al. (2005), chronic inflammation, these roles can be reversed—adaptive other studies show that the levels of TNF-α, interferon-γ immune responses can cause ongoing and excessive activa- and interleukin-10 may be increased by probiotic supple- tion of innate immune cells (de Visser et al. 2006). Probiotic mentation (Jiang et al. 2009; Lee et al. 2008). Lan et al. bacteria can modulate this over-response. (2008) reported increased induction of apoptosis by Another possible mechanism of carcinogenesis preven- Propionibacterium freudenreichii TL133 in colonic muco- tion is the activation of natural killer (NK) cells. NK cells are sal crypts of human microbiota-associated (HMA) rats large granular lymphocytes derived from bone marrow, and treated with DMH (1,2-dimethylhydrazine). HMA rats con- these cells display non-MHC-restricted cytotoxicity against stitute a well-validated model for experimental studies, aimed a variety of tumours, in part by producing mediators with at evaluating the effects of functional foods and probiotics in anti-angiogenic properties (de Visser et al. 2006). It is well GI physiology. The induction of apoptosis occurs only in recognized that NK cells act as cytolytic effector cells of the animals treated with DMH, suggesting that it specifically innate immune system. Oral feeding of Lactobacillus casei targets damaged cells. The authors suggest that daily Shirota (LcS) to MC-treated mice rendered their NK cells administration of P. freudenreichii may help in the elimination tumouricidal in terms of both quality and quantity, resulting of damaged cells by apoptosis within the colon epithelium. in the suppression of tumour incidence (Takagi et al. 2001). This protective role against colon cancer should be further Yet another possible mechanism of action may involve confirmed by long-term in vivo carcinogenesis assays in dendritic cells. Dendritic cells, as previously highlighted, are order to evaluate their effect on colorectal tumour incidence. thought to be one of the most important types of cells involved Altonsy et al. (2010) compared the role of pathogenic in the presentation of several antigens and in the production of bacteria, probiotic and commensal bacteria on the induction cytokines. Recent studies show Lactobacillus strain-specific of apoptosis in Caco-2 cells in vitro. The results show how activity in prevention of murine tumorigenesis and in the two probiotic strains studied (Lactobacillus rhamnosus induction of IL-12 release by bone marrow-derived dendritic LGG and B. animalis subsp. lactis Bb12) are able to induce cells in vitro (Takagi et al. 2008). Recently, Matsumoto et al. the apoptotic pathway, albeit to a lesser extent compared to (2009) described the role of the LAB strain LcS in pathogenic bacteria (EPEC, VTEC), via the mitochondrial prevention of colon cancer by targeting the immune system. route rather than through the Fas receptor pathway. It is Using a mouse model, they report that L. casei produces a possible that the weak apoptotic effects induced by these polysaccharide that inhibits colon carcinogenesis by sup- strains may be important in driving turnover of the pressing synthesis of IL-6 and signal transducer and activator intestinal epithelium, which could reduce accumulation of of transcription 3 (STAT3) (Kumar et al. 2010). Usually, IL-6 mutations in long-lived epithelial cells. induces phosphorylation of STAT3, which mediates the expression of a variety of genes and plays a key role in Putative molecular mechanisms responsible for colon many cellular processes such as cell growth and apoptosis. cancer reduction by probiotic bacteria Apoptotic deletion The mechanisms by which probiotics affect human health beneficially can be divided into different categories, as Apoptosis is an important innate regulatory process in the delineated in the previous paragraphs, including: strength- protection against the development of cancer. Apoptosis ening of the intestinal barrier, modulation of the immune leads to the removal of cells with genomic instability response, antagonism of pathogens. The molecular details caused by tumor development or by exposure to carcino- behind these mechanisms are now being investigated 24 Ann Microbiol (2012) 62:15–30 through genomics-based approaches to identify the relevant – Some probiotic strains induce expression of the molecular interaction between probiotics and host cells both antimicrobial peptide β-defensin-2 (hBD-2). β defen- in vitro and in vivo. sins are small antimicrobial peptides of the innate immune system produced in response to microbial – Probiotic microorganisms may interact directly with infection of mucosal tissue and skin; among the dendritic cells (DCs). As already illustrated in the defensin family the β-type is distributed most widely, section above on Immune system stimulation, DCs being secreted by leukocytes and epithelial cells of intervene in early bacterial recognition and consequently many kinds. Activation of hBD-2 might lead to the have a role in shaping T-cell responses. Several probiotic enhancement of the barrier effect of the intestinal species have been shown to induce the in vitro maturation mucosa and could explain, at least in part, the ability and cytokine expression of DCs. It seems that Lactoba- of specific probiotics to inhibit pathogen growth in the cillus–DC interactions are mediated by the bacterium gut (Marco et al. 2006). binding to the dendritic lectin (DC-SIGN). Lactobacillus – There is also evidence that probiotics can modulate strains that are able to interact with this lectin led to the MUC gene expression. Mucins are a family of large, development of populations of regulatory T-cells that heavily glycosylated proteins. Some mucins are produce interleukin-10. They can also induce hypores- membrane-bound while others are secreted on mucosal ponsive CD4 T-cell populations. surfaces and play an important role in maintaining – Probiotic microorganisms could be recognized by mucosal barriers. MUC genes encode mucin monomers intestinal epithelial cells (IEC) or colon epithelial cells that are post-translationally modified by exceptionally (CEC) through interaction between Toll-like receptors abundant glycosylation. The increased expression of (TLRs) and bacterial components. The signal thus certain specific MUC genes instead of others may produced arrives in the nucleus through a signal create a highly difficult situation for pathogen binding. transduction pathway that can modulate gene expres- The anti-pathogenic activities (Britton and Versalovic sion of different cytokines. 2008; Thirabunyanon 2011) of probiotics have already been – Modulation of inflammatory responses may also be mentioned; mechanisms of pathogen load reduction are effected through inactivation of the NF-κB signalling briefly summarised below: pathway; there are two possible mechanisms for this. – competitive exclusion (CE): adhesin-mediated attach- Soluble components produced by probiotic bacteria are ment of probiotics excludes pathogens; recognized by IEC, leading to inhibition of protea- – aggregation: probiotics aggregate with pathogens, somes, and consequently to inhibition of the transcrip- leading to expulsion from the gut; tion factor NF-κB. The proteasome is in fact a protein – nutrient competition: probiotics compete with patho- complex whose main function is to degrade unneeded gens for essential nutrients; or damaged proteins by proteolysis. This complex – masking: masking of intestinal receptors for enter- usually degrades NF- κB inhibitor (I-κB), enabling otoxins binding by probiotic adhesins; NF-κB to access the nucleus. If I-κB is not degraded, – production of antimicrobial substances: probiotics it can bind to NF-κB and inhibit its translocation produce hydrogen peroxide (H O ), bacteriocins (e.g. across the nuclear membrane. Another way to inhibit 2 2 lactocins, helveticins, lactacins, curvacins, nisin, bifi- NF-κB is through interaction of bacterial CpG DNA docin) and organic acids, the latter lowering pH, create with TLR9; the result is, again, the prevention of I-κB a forbidding environment for a wide range of harmful degradation. microorganisms. Other mechanisms have also been suggested to explain It is probable that probiotic strains exert their effects at probiotic strengthening of the intestinal barrier. different stages of carcinogenesis. As evidenced by Commane – Exposure of IEC (and also CEC) to soluble compo- et al. (2005), two different events with their mechanisms nents produced by probiotic microorganisms leads to could be distinguished: the production of specific heat shock proteins (HSPs). These proteins have various functions and are also (1) anti-initiation events: probiotics may alter carcinogen known for their ability to maintain and stabilise metabolism and improve detoxification; they may cytoskeletal integrity. Induction of HSPs may be enhance DNA repair and scavenge electrophiles. derived from proteasome (and therefore NF-κB) inhi- (2) anti promotion events: probiotics may alter gene bition or through signal transduction pathway activa- expression, enhance immunity, suppress inflammation, tion involving mitogen-activated protein kinases promote differentiation, suppress proliferation and (MAPKs) that leads to HSP expression. increase apoptosis. Ann Microbiol (2012) 62:15–30 25 Human Studies epidemiological data. Because of the multitude of dietary assessment methods and food composition tables used in Numerous in vitro studies on human cell lines or animal nutritional epidemiological studies, heterogeneous results studies have investigated the efficacy of probiotic, prebiotic are likely to occur. Standardisation of study methods and synbiotic supplements in reducing the incidence of would facilitate pooled analysis, thereby permitting more colon cancer development. Some studies focus specifically reliable conclusions regarding diet–disease relationships on enzymatic activities of probiotic bacteria against (Friedenreich et al. 1994). carcinogen or genotoxic compounds, or on the immune An interesting overview of human trials on the effect of stimulation of GALT (as discussed in Mechanisms fibre incidence on colon cancer development is reviewed by underlying cancer prevention). Young et al. (2005), where authors deal with the different In vivo human clinical studies, on the contrary, are still types of human epidemiological studies separately (i.e. sparse. Several reviews have attempted to analyse and correlative studies, case control studies, and prospective cluster available case-control studies, or to extrapolate studies). The findings of this work show the importance of results from other epidemiological studies not conducted an intake of at least 35 g fibre/day in order to even consider directly with probiotic and/or prebiotic supplements. The taking the epidemiological study into consideration; more- point at issue here is that it is often not possible to compare over, it is stressed that dietary fibre might be most different in vivo experimental results because of the protective when consumed in natural food sources rather variability in trial designs or the lack of accurate informa- than as a synthetic supplement (Young et al. 2005). tion regarding a particular study. On the other hand, a review by Capurso et al. (2006) Pool-Zobel (2005) and Pool-Zobel and Sauer (2007) gives an overview of available human studies with pro- review experimental and human data about the effect of biotic bacteria. This article has a meaningful title: “Pro- prebiotics, focusing on inulin-type fructans and their biotics and the incidence of colorectal cancer: when incidence on colon cancer risk. They conclude that animal evidence is not evident”. The authors analysed existing studies largely support the assumption that inulin-type data from basic science (animal and in vitro models) and fructans may reduce colorectal cancer (CRC) incidence human (epidemiological and interventional) studies to when supplemented during the initial stages of cancer highlight areas for which more evidence is necessary. They development. Discrepancies can also be found in human interrogated Medline for studies analysing the risk of CRC epidemiological studies carried out to correlate high-fibre and the use of probiotics, as well as screening the diet with the risk of CRC (Liong 2008; Fuchs et al. 1999). references of identified papers. Once again, this review Several such studies deal with the effects of fibre. stresses the paucity of human epidemiological studies Dietary fibres are carbohydrate polymers that are not designed specifically to analyse the effect of probiotics on hydrolysed by the endogenous enzymes of the human CRC incidence; moreover, authors underline the presence intestine. They are composed of a soluble fraction of important confounding factors, such as the role of fibre, (soluble fibre, which also includes prebiotic compounds) dairy products and vitamin D, which are often present. and an insoluble fraction (insoluble fibre, e.g. lignin) that Conflicting epidemiological data regarding the impact of can be present in different ratios. Much evidence fermented dairy product consumption in humans have been supports the view that fibre interacts with the intestinal gathered by authors. Also in this case, human epidemio- microbiota. The magnitude of interaction depends on the logical and interventional studies still do not seem to composition. Some of the effects of fibre, e.g. increased support the promising results observed under experimental faecal bulk and decreased colonic transit, are linked to conditions. These discrepancies may be explained partially fibre itself, while other beneficial effects are linked to by the use of bacterial strains lacking the appropriate fibre fermentation by host microbiota (Queiroz-Monici et characteristics, again stressing the concept that different al. 2005;Roseet al. 2007), leading to a modulation of probiotics might have specific and different clinical microbiota composition. Works reviewed by Liong (2008) applications. In fact, epidemiological studies examine the and the prospective study of Fuchs et al. (1999)stressthat action of “fermented dairy products”, which do contain no significant association was found between fibre intake naturally occurring probiotics but of unknown strains and in and the risk of colorectal adenoma. However, these studies undefined amounts. Therefore, even though a large body of do not evaluate a particular prebiotic compound but rather evidence supports the potential anticarcinogenic action of the incidence of an high-fibre diet, with no detailed probiotics on the basis of the results obtained in both in description of either fibre composition or fibre source. vitro and in vivo models, further evidence is still needed From the epidemiologic point of view, as stressed by (Capurso et al. 2006). Friedenreich et al. (1994), methodological factors can Concluding, a noteworthy human intervention study that influence the results from pooled analysis of nutritional was performed within the EU project SYNCAN (Van Loo 26 Ann Microbiol (2012) 62:15–30 et al. 2005) has yielded some interesting results. This tract. However, their effect is also influenced by strain project involves the integration of an in vitro study to select specificity, host (i.e. genetic factors, indigenous microbiota) the most suitable synbiotic preparation, the application of and by environmental variants (e.g. diet, lifestyle, stress this synbiotic in an in vivo rat model of chemically induced conditions etc.). It is of the utmost importance that the colon cancer, and, as the core of the project, an investiga- peculiar characteristics of a given probiotic strain are tion of synbiotic effects in a human intervention study. The clearly defined in order to target and associate a particular assessment of the survival during gastric transit of the strain to a defined disorder. Moreover, an appropriate administered probiotics (Bifidobacterium animalis subsp. prebiotic compound should be selected and associated to a lactis Bb12 and Lactobacillus rhamnosus GG) was per- specific probiotic microorganism to favour a synergistic formed in three healthy volunteers in a separate study. effect. Unfortunately, despite the huge quantity of data Subsequently, a 12-week randomised, double-blind, available in vitro and on animal models, these outcomes are placebo-controlled trial of a synbiotic food supplement for not often supported by human data. The complexity of reduction in cancer risk bio-markers is carried out. The creating a series of long-term human intervention studies synbiotic used in this study was composed of the two should be overcome and new human studies on probiotics probiotics listed above and the oligofructose-enriched and prebiotics should be financed in order to generate inulin Synergy1 . Polypectomised and colon cancer sub- uncontroversial experimental evidence. Further research is jects having previously undergone ‘curative resection’ for required to identify probiotic, prebiotic or synbiotic colon cancer were selected and assigned randomly to combinations that will be more effective for humans in placebo or synbiotic group. The ability of the synbiotic different conditions. It is very likely that there will be no combination to modulate the gut microbiota was demon- treatment that is ideal for all cases. Probably, the great strated in both the cancer and the polypectomised subjects. efforts of the scientific community to identify the genetic The selectivity of fermentation was shown by the bifido- determinants involved in the health-promoting effects of genic effect, which was accompanied by a decrease of probiotic bacteria (i.e. probiogenomics) (Ventura et al. coliforms in both polypectomised and cancer patient 2009), together with new well-designed human trials, will groups, and a decrease of Clostridium perfringens in the yield significant insights into pre- and pro-biotic mecha- polypectomised group. The authors stress that, since the nisms. However, it is feasible to conclude that pro-, pre- synbiotic supplement modulates the microbiota, it can be and synbiotics hold great potential as a strategy for the hypothesised that the changes in biomarkers monitored in prevention of colorectal cancer. the human anticancer study in test groups vs control group are likely to be the consequence of the administration of an References active synbiotic preparation. The analyses of various markers in this human study show reduced genotoxicity, increased caecal SCFA, particularly butyrate, priming of the Ahotupa M, Saxelin M, Korpela R (1996) Antioxidant properties of Lactobacillus GG. Nutr Today Suppl 31:51–52 immune system to be more efficient to fight cancer cells Alonso L, Cuesta EP, Gilliland SE (2003) Production of free and counteract inflammation, and a reduction in DNA conjugated linoleic acid by Lactobacillus acidophilus and damage (Van Loo et al. 2005). Lactobacillus casei of human intestinal origin. J Dairy Sci 86:1941–1946 Altonsy MO, Andrews SC, Yuohy KM (2010) Differential induction of apoptosis in human colonic carcinoma cells (Caco-2) by Conclusions Atopobium, and commensal, probiotic and enteropathogenic bacteria: mediation by the mitochondrial pathway. Int J Food The use of probiotics, prebiotics and synbiotics to prevent Microbiol 137:190–203 Annuk H, Shchepetova J, Kullisaar T, Songisepp E, Zilmer M, colon cancer has gained much attention in the last decade Mikelsaar M (2003) Characterization of intestinal lactobacilli as due to the fact that in vitro systems and studies in a wide putative probiotic candidates. J Appl Microbiol 94:403–412 range of animal models provide considerable evidence that Ballongue J (2004) Bifidobacteria and probiotic action. In: Salminen S, von Wright A, Ouwehand AC (eds) Lactic acid bacteria. they exert anti-neoplastic effects. This review reports an Microbiological and functional aspects, 3rd edn. Dekker, New overview of the possible mechanisms that could underlie York, p 67 the preventative action of probiotics and prebiotics against Barber DA, Harris SR (1994) Oxygen free radicals and antioxidants: a CRC development. The evolution of CRC is a complicated review. Am Pharm 34:26–35 Barrett E, Ross RP, Fitzgerald GF, Stanton C (2007) Rapid screening multistep process influenced by genetic as well as by method for analyzing the conjugated linoleic acid production environmental factors. Similar considerations can be capabilities of bacterial cultures. Appl Environ Microbiol reported for probiotics and prebiotics. Their preventative 73:2333–2337 effect on CRC development is possibly the sum of a series Belury MA (2002) Inhibition of carcinogenesis by conjugated linoleic of beneficial effects that these supplements exert in the GI acid: potential mechanisms of action. J Nutr 132:2995–2998 Ann Microbiol (2012) 62:15–30 27 Bernstein H, Bernstein C, Payne CM, Dvorakova K, Garewal H Di Giacinto C, Marinaro M, Sanchez M, Strober W, Boirivant M (2005) Bile acids as carcinogens in human gastrointestinal (2005) Probiotics ameliorate recurrent Th1-mediated murine cancers. Mutat Res 589:47–65 colitis by inducing IL-10 and IL-10-dependent TGF-β-bearing Bernstein H, Bernstein C, Payne CM, Dvorak K (2009) Bile acids as regulatory cells. J Immunol 174:3237–3246 endogenous etiologic agents in gastrointestinal cancer. World J Duthie SJ (1999) Folic acid deficiency and cancer: mechanisms of Gastroenterol 15(27):3329–3340 DNA instability. Brit Med Bull 55(3):578–592 Bhattacharya A, Banu J, Rahman M, Causey J, Fernandes G (2006) EFSA (2008) The EFSA Journal 923:1–48 Biological effects of conjugated linoleic acids in health and El-Nezami H, Kankaanpää P, Salminen S, Ahokas J (1998a) disease. J Nutr Biochem 17:789–810 Physicochemical alterations enhance the ability of dairy strains Biavati B, Mattarelli P (2006) The family Bifidobacteriaceae. In: of lactic acid bacteria to remove aflatoxin from contaminated Dworkin M, Falkow S, Rosenberg E, Schleifer K-H, Stackebrandt media. J Food Prot 61:466–468 E (eds) The prokaryotes, 3rd edn, vol 3: a handbook of the biology El-Nezami H, Kankaanpää P, Salminen S, Ahokas J (1998b) Ability of of bacteria: Archea, Bacteria: Firmicutes, Actinomycetes. Springer, dairy strains of lactic acid bacteria to bind a common food New York, pp 322–382 carcinogen, aflatoxin B1. Food Chem Toxicol 36:321–326 Biavati B, Vescovo M, Torriani S, Bottazzi V (2000) Bifidobacteria: El-Nezami HS, Chrevatidis A, Auriola S, Salminen S, Mykkänen H history, ecology, physiology and applications. Ann Microbiol (2002) Removal of common Fusarium toxins in vitro by strains 50:117–131 of Lactobacillus and Propionibacterium. Food Addit Contam Bingham SA, Day NE, Luben R, Ferrari P, Slimani N, Norat T, Clavel- 19:680–686 Chapelon F, Kesse E, Nieters A, Boeing H et al (2003) Dietary Evan GI, Vousden KH (2001) Proliferation, cell cycle and apoptosis in fibre in food and protection against colorectal cancer in the cancer. Nature 411(6835):342–348 European Prospective Investigation into Cancer and nutrition Ewaschuk JB, Walker JW, Diaz H, Madsen KL (2006) Bioproduction (EPIC): an observational study. Lancet 361:1496–1501 of conjugated linoleic acid by probiotic bacteria occurs in vitro Blau S, Rubinstein A, Bass P, Singaram C, Kohen R (1999) Differences and in vivo in mice. J Nutr 136:1483–1487 in the reducing power along the rat GI tract: lower antioxidant FAO/WHO (2002) Joint FAO/WHO (Food and Agriculture Organization/ capacity of the colon. Mol Cell Biochem 194(1–2):185–191 World Health Organization) working group report on drafting Britton RA, Versalovic J (2008) Probiotics and gastrointestinal guidelines for the evaluation of probiotics in food. London, Ontario, infections. Interdiscip Perspect Infect Dis 2008:290769, Epub 4 Canada.guidelines for the evaluation of probiotics in food. Joint Feb 2009 working group report on drafting. London, Ontario 1–11 Brown JM, Attardi LD (2005) The role of apoptosis in cancer Fazeli MR, Hajimohammadali M, Moshkani A, Samadi N, Jamalifar development and treatment response. Nat Rev Cancer 5:231–237 H, Khoshayand MR, Vaghari E, Pouragahi S (2009) Aflatoxin B1 Bruce WR, Giacca A, Medline A (2000) Possible mechanisms relating binding capacity of autochthonous strains of lactic acid bacteria. diet and risk of colon cancer. Cancer Epidemiol Biomarkers Prev J Food Protect 72(1):189–192 9(12):1271–1279 Femia AP, Luceri C, Dolara P, Giannini A, Biggeri A, Salvadori M, Bueno DJ, Casale CH, Pizzolitto RP, Salvano MA, Oliver G (2007) Clune Y, Collins KJ, Paglierani M, Caderni G (2002) Anti- Physical adsorption of aflatoxin B1 by Lactic Acid Bacteria and tumorigenic activity of the prebiotic inulin enriched with Saccharomyces cerevisiae: a theoretical model. J Food Protect 70 oligofructose in combination with the probiotics Lactobacillus (9):2148–2154 rhamnosus and Bifidobacterium lactis on azoxymethane-induced Capurso G, Marignani M, Delle Fave G (2006) Probiotics and the colon carcinogenesis in rats. Carcinogenesis 23(11):1953–1960 incidence of colorectal cancer: when evidence is not evident. Friedenreich CM, Brant RF, Riboli E (1994) Influence of methodo- Digest Liver Dis 38(S2):S277–S282 logic factors in a pooled analysis of 13 case-control studies of Cebra JJ (1999) Influences of microbiota on intestinal immune system colorectal cancer and dietary fiber. Epidemiology 5(1):66–79 development. Am J Clin Nutr 69(S):1046S–1051S Fuchs CS, Giovannucci EL, Colditz GA, Hunter DJ, Stampfer MJ, Choi SS, Kim Y, Han KS, You S, Oh S, Kim SH (2006) Effects of Rosner B, Speizer FE, Willet WC (1999) Dietary fiber and the Lactobacillus strains on cancer cell proliferation and oxidative risk of colorectal cancer and adenoma in women. New Engl J stress in vitro. Lett Appl Microbiol 42:452–458 Med 340(3):169–176 Coakley M, Ross RP, Nordgren M, Fitzgerald G, Devery R, Stanton C Fuchs S, Sontag G, Stidl R, Ehrlich V, Kundi M, Knasmüller S (2008) (2003) Conjugated linoleic acid biosynthesis by human-derived Detoxification of patulin and ochratoxin A, two abundant Bifidobacterium species. J Appl Microbiol 94:138–145 mycotoxins, by lactic acid bacteria. Food Chem Toxicol Coakley M, Johnson MC, McGrath E, Rahman S, Ross RP, Fitzgerald 46:1398–1407 GF, Devery R, Stanton C (2006) Intestinal bifidobacteria that Fuller R (1989) Probiotics in man and animals: a review. J Appl produce trans-9, trans-11 CLA: a fatty acid with anti- Bacteriol 66:365–378 proliferative activity against human colon SW480 and HT-29 Fuller R (1991) Probiotics in human medicine. Gut 32:439–442 cancer cells. Nutr Cancer 56:95–102 Gaggìa F, Mattarelli P, Biavati B (2010) Probiotics and prebiotics in Coakley M, Banni S, Johnson MC, Mills S, Devery R, Fitzgerald G, animal feeding for safe food products. Int J Food Microbiol 141: Paul Ross R, Stanton C (2009) Inhibitory effect of conjugated S15–S28 alpha-linolenic acid from bifidobacteria of intestinal origin on García P, Rodríguez L, Rodríguez A, Martínez B (2010) Food SW480 cancer cells. Lipids 44(3):249–256 biopreservation: promising strategies using bacteriocins, bacter- Commane D, Hughes R, Shortt C, Rowland I (2005) The potential iophages and endolysins. Trends Food Sci Technol 21:373–382 mechanisms involved in the anti-carcinogenic action of pro- Gibson GR, Roberfroid MB (1995) Dietary modulation of the human biotics. Mutat Res 591:276–289 colonic microbiota: introducing the concept of prebiotics. J Nutr De Visser KE, Eichten A, Coussens LM (2006) Paradoxical roles of 125:1401–1412 the immune system during cancer development. Nat Rev Cancer Guarner F, Malagelada JR (2003) Gut flora in health and disease. 6:24–37 Lancet 361:512–519 De Vuyst L, Leroy F (2007) Bacteriocins from Lactic Acid Bacteria: Guillén H, Curiel JA, Landete JM, Muñoz R, Herraiz T (2009) production, purification, and food applications. J Mol Microbiol Characterization of a nitroreductase with selective nitroreduction Biotechnol 13:194–199 properties in the food and intestinal lactic acid bacterium 28 Ann Microbiol (2012) 62:15–30 Lactobacillus plantarum WCFS1. J Agric Food Chem 57 Lamprecht SA, Lipkin M (2003) Chemoprevention of colon cancer by (21):10457–10465 calcium, vitamin D and folate: molecular mechanisms. Nat Rev Halliwell B (1996) Mechanisms involved in the generation of free Cancer 3:601–614 radicals. Pathos Biol 44:6–13 Lan A, Bruneau A, Bensaada M, Philippe C, Bellaud P, Rabot S, Jan Halliwell B (2007) Oxidative stress and cancer: Have we moved G (2008) Increased induction of apoptosis by Propionibacterium forward? Biochem J 401:1–11 freudenreichii TL133 in colonic mucosal crypts of human Hao WL, Lee YK (2004) Microflora of the gastrointestinal tract: a microbiota-associated rats treated with 1,2-dimethylhydrazine. review. Methods Mol Biol 491–502. Br J Nutr 100:1251–1259 Haskard C, Binnion C, Ahokas J (2000) Factors affecting the Le Leu RK, Brown IL, Hu Y, Bird AR, Jackson M, Esterman A, sequestration of aflatoxin by Lactobacillus rhamnosus strain Young GP (2005) A synbiotic combination of resistant starch and GG. Chem Biol Interact 128:39–49 Bifidobacterium lactis facilitates apoptotic deletion of Haskard CA, El-nezami HS, Kankaanpää PE, Salminen S, Ahokas JT carcinogen-damaged cells in rat colon. J Nutr 135:996–1001 (2001) Surface binding of aflatoxin B1 by lactic acid bacteria. Le Leu RK, Hu Y, Brown IL, Woodman RJ, Young GP (2010) Appl Environ Microb 67(7):3086–3091 Synbiotic intervention of Bifidobacterium lactis and resistant Hattori M, Taylor TD (2009) The human intestinal microbiome: a new starch protects against colorectal cancer development in rats. frontier of human biology. DNA Res 16:1–12 Carcinogenesis 31(2):246–251 He B, Xu W, Santini PA, Polydorides AD, Chiu A, Estrella J, Shan M, LeBlanc JG, Matar C, Valdéz JC, LeBlanc J, Perdigon G (2002) Chadburn A, Villanacci V, Plebani A, Knowles DM, Rescigno M, Immunomodulating effects of peptidic fractions issued from milk Cerutti A (2007) Intestinal bacteria trigger t cell-independent fermented with Lactobacillus helveticus. J Dairy Sci 85:2733–2742 immunoglobulin A class switching by inducing epithelial-cell Lee W-J (2009) Bacterial-modulated host immunity and stem cell secretion of the cytokine APRIL. Immunity 26:812–826 activation for gut homeostasis. Genes Dev 23(19):2260–2265 Hernandez-Mendoza A, Guzman-de-Peña D, Garcia HS (2009) Key Lee DK, Jang S, Kim MJ, Kim JH, Chung MJ, Kim KJ, Ha NJ (2008) role of teichoic acids on aflatoxin B1 binding by probiotic Anti-proliferative effects of Bifidobacterium adolescentis bacteria. J Appl Microbiol 107:395–403 SPM0212 extract on human colon cancer cell lines. BMC Cancer Hord NG (2008) Eukaryotic-microbiota crosstalk: potential mecha- 8:310 nisms for health benefits of prebiotics and probiotics. Annu Rev Ley RE, Peterson DA, Gordon JI (2006) Ecological and evolutionary Nutr 28:215–231 forces shaping microbial diversity in the human intestine. Cell Humblot C, Murkovic M, Rigottier-Gois L, Bensaada M, Bouclet A, 124:837–848 Andrieux C, Anba J, Rabot S (2007) β-Glucuronidase in human Lin MY, Chang FJ (2000) Antioxidative effect of intestinal bacteria intestinal microbiota is necessary for the colonic genotoxicity of Bifidobacterium longum ATCC 15708 and Lactobacillus acid- the food-borne carcinogen 2-amino-3-methylimidazo[4,5-f]quin- ophilus ATCC 4356. Dig Dis Sci 45:1617–1622 oline in rats. Carcinogenesis 28(11):2419–2425 Lin TY, Lin CW, Lee CH (1999) Conjugated linoleic acid concentra- International Agency for Research on Cancer (1993) Some naturally tion as affected by lactic cultures and added linoleic acid. Food occurring substances: food items and constituents heterocyclic Chem 67:1–5 aromatic amines and mycotoxins. IARC, Lyon Liong M-T (2008) Roles of probiotics and prebiotics in colon cancer Iyer R, Tomar SK (2009) Folate: a functional food constituent. J Food prevention: postulated mechanisms and in vivo evidence. Int J Sci 74(9):R114–R122 Mol Sci 9:854–863 Jain S, Yadav M, Menon S, Yadav H, Marotta F (2009) Anticarcino- Macfarlane GT, Cummings JH (1999) Probiotics and prebiotics: can genic effects of probiotics, prebiotics, and synbiotics. In: regulating the activities of intestinal bacteria benefit health. BMJ Finocchiaro ET, Cho SS (eds) Handbook of prebiotics and 318:999–1003 probiotics: ingredients, health benefits and food applications, 1st Macpherson AJ, Harris NL (2002) Interactions between commensal edn. CRC, Boca Raton, pp 273–287 intestinal bacteria and the immune system. Nat Rev Immunol Jiang H-R, Lu Z-G, Ma Y-Y, Liu N (2009) Target colonization of 4:478–485 Bifidobacterium bifidum in tumor-bearing mouse model and its Macpherson AJ, Slack E (2007) The functional interactions of immune activation on macrophages. Tumor 29(8):721–726 commensal bacteria with intestinal secretory IgA. Curr Opin Kabak B, Dobson ADW (2009) Biological strategies to counteract the Gastroen 23(6):673–678 effects of mycotoxins. J Food Protect 72(9):2006–2016 Madsen K, Cornish A, Soper P, McKaigney C, Jijon H, Yachimec C, Kelley NS, Hubbard NE, Erickson KL (2007) Conjugated linoleic Doyle J, Jewell L, De Simone C (2001) Probiotic bacteria acid isomers and cancer. J Nutr 137:2599–2607 enhance murine and human intestinal epithelial barrier function. Kishino S, Ogawa J, Omura Y, Matsumura K, Shimizu S (2002) Gastroenterology 121:580–591 Conjugated linoleic acid production from linoleic acid by lactic Maldonado Galdeano C, de Moreno de LeBlanc A, Vinderola G, acid bacteria. J Am Oil Chem Soc 79:159–163 Bibas Bonet ME, Perdigon G (2007) Proposed model: mecha- Kruszewska D, Lan J, Lorca G, Yanagisawa N, Marklinder I, Ljungh nisms of immunomodulation induced by probiotic bacteria. Clin Å (2002) Selection of lactic acid bacteria as probiotic strains by Vaccine Immunol 14(5):485–492 in vitro tests. Microb Ecol Health Dis 29:37–49 Marchesi JR (2010) Prokaryotic and eukaryotic diversity of the human Kullisaar T, Zilmer M, Mikelsaar M, Vihalemm T, Annuk H, Kairane gut. Adv Appl Microbiol 72:43–62 C, Kilk A (2002) Two antioxidative lactobacilli strains as Marco ML, Pavan S, Kleerebezem M (2006) Towards understanding promising probiotics. Int J Food Microbiol 72:215–224 molecular modes ofprobiotic action. Curr Opin Biotechnol Kumar M, Kumar A, Nagpal R, Mohania D, Behare P, Verma V, 17:204–210 Kumar P, Poddar D, Aggarwal PK, Henry CJK, Jain S, Yadav H Marotta F, Naito Y, Minelli E, Tajiri H, Bertuccelli J, Wu CC, Min CH, (2010) Cancer-preventing attributes of probiotics: an update. Int J Hotten P, Fesce E (2003) Chemopreventive effect of a probiotic Food Sci Nutr 61(5):473–496 preparation on the development of preneoplastic and neoplastic Lahtinen SJ, Haskard CA, Ouwehand AC, Salminen SJ, Ahokas JT colonic lesions: an experimental study. Hepatogastroenterology (2004) Binding of aflatoxin B1 to cell wall components of 50(54):1914–1918 Lactobacillus rhamnosus strain GG. Food Addit Contam 21:158– Marotti I, Bonetti A, Biavati B, Catizone P, Dinelli G (2007) 164 Biotransformation of common bean (Phaseolus vulgaris L) Ann Microbiol (2012) 62:15–30 29 flavonoid glycosides by Bifidobacterium species from human Linneberg A, Nielsen HB, Pelletier E, Renault P, Sicheritz-Ponten intestinal origin. J Agric Food Chem 55:3913–3919 T, Turner K, Zhu H, Yu C, Li S, Jian M, Zhou Y, Li Y, Zhang X, Matsumoto S, Hara T, Nagaoka M, Mike A, Mitsuyama K, Sako T, Li S, Qin N, Yang H, Wang J, Brunak S, Doré J, Guarner F, Yamamoto M, Kado S, Takada T (2009) A component of Kristiansen K, Pedersen O, Parkhill J, Weissenbach J, MetaHIT polysaccharide peptidoglycan complex on Lactobacillus induced Consortium, Bork P, Ehrlich SD, Wang J (2010) A human gut an improvement of murine model of inflammatory bowel disease microbial gene catalogue established by metagenomic sequenc- and colitis-associated cancer. Immunology 128:e170–e180 ing. Nature 464(7285):59–65 McBain AJ, Macfarlane GT (1998) Ecological and physiological Queiroz-Monici KS, Costa GEA, da Silva N, Reis SMPM, de Oliveira studies on large intestinal bacteria in relation to production of AC (2005) Bifidogenic effect of dietary fiber and resistant starch hydrolytic and reductive enzymes involved in formation of from leguminous on the intestinal microbiota of rats. Nutrition genotoxic metabolites. J Med Microbiol 47(5):407–416 21:602–608 McCracken VJ, Lorenz RG (2001) The gastrointestinal ecosystem: a Rafii F, Franklin W, Cerniglia CE (1990) Azoreductase activity of precarious alliance among epithelium, immunity and microbiota. anaerobic bacteria isolated from human intestinal microflora. Cell Microbiol 3(1):1–11 Appl Environ Microbiol 56(7):2146–2151 Mills S, Stanton C, Ross RP (2009) Microbial production of Rafter J, Bennett M, Caderni G, Clune Y, Hughes R, Karlsson PC, bioactives: from fermented functional foods to probiotic mech- Klinder A, O’Riordan M, O’Sullivan GC, Pool-Zobel B, anisms. Aust J Dairy Technol 64(1):41–49 Rechkemmer G, Roller M, Rowland I, Salvadori M, Thijs H, Mowat AM (2003) Anatomical basis of tolerance and immunity to Van Loo J, Watzl B, Collins JK (2007) Dietary synbiotics reduce intestinal antigens. Nat Rev Immunol 3:331–341 cancer risk factors in polypectomized and colon cancer patients. Nagao K, Yanagita T (2005) Conjugated fatty acids in food and their Am J Clin Nutr 85(2):488–496 health benefits. J Biosci Bioeng 100:152–157 Rastall RA, Gibson GR, Gill HS, Guarner F, Klaenhammer TR, Pot B, Neutra MR, Pringault E, Kraehenbuhl J-P (1996) Antigen sampling Reid G, Rowland IR, Sanders ME (2005) Modulation of the across epithelial barriers and induction of mucosal immune microbial ecology of the human colon by probiotics, prebiotics responses. Annu Rev Immunol 14:275–300 and synbiotics to enhance human health: an overview of enabling O’Flaherty S, Saulnier DM, Pot B, Versalovic J (2010) How can science and potential applications. FEMS Microbiol Ecol 52:145–152 probiotics and prebiotics impact mucosal immunity? Gut Microbes 1(5):293–300 Reddy BS, Hanson D, Mangat S, Mathews L, Sbaschnig M, Sharma O’Hara AM, Shanahan F (2006) The gut flora as a forgotten organ. C, Simi B (1980) Effect of high-fat, high-beef diet and of mode EMBO Rep 7:688–693 of cooking of beef in the diet on fecal bacterial enzymes and Oatley JT, Rarick MD, Ji GE, Linz JE (2000) Binding of aflatoxin B1 fecal bile acids and neutral sterols. J Nutr 110:1880–1887 to bifidobacteria in vitro. J Food Protect 63:1133–1136 Roberfroid MB (1998) Prebiotics and synbiotics: concepts and Özdemir Ö (2010) Various effects of different probiotic strains in nutritional properties. Br J Nutr 80:S197–S202 allergic disorders: An update from laboratory and clinical data. Roberfroid M (2007) Prebiotics: the concept revisited. J Nutr Clin Exp Immunol 160(3):295–304 137:830S–837S Park J-H, Um J-I, Lee B-J, Goh J-S, Park S-Y, Kim W-S, Kima P-H Rodríguez-Alcalá LM, Braga T, Gomes A, Malcata FX, Fontecha J (2002) Encapsulated Bifidobacterium bifidum potentiates intesti- (2011) Quantitative and qualitative determination of CLA nal IgA production. Cell Immunol 219:22–27 produced by Bifidobacterium and lactic acid bacteria by Parke DV, Ioannides C (1990) Role of cytochrome P-450 in mouse combining spectrophotometric and Ag -HPLC techniques. Food liver tumor production. Prog Clin Biol Res 331:215–230 Chem 125:1373–1378. doi:10.1016/j.foodchem.2010.10.008 Perdigon G, Vintiñi E, Alvarez S, Medina M, Medici M (1999) Study of Rook GA, Brunet LR (2005) Microbes, immunoregulation, and the the possible mechanisms involved in the mucosal immune system gut. Gut 54:317–320 activation by lactic acid bacteria. J Dairy Sci 82(6):1108–1114 Rose DJ, DeMeo MT, Keshavarzian A, Hamaker BR (2007) Influence Perdigón G, Maldonado Galdeano C, Valdez JC, Medici M (2002) of dietary fiber on inflammatory bowel disease and colon cancer: Interaction of lactic acid bacteria with the gut immune system. importance of fermentation pattern. Nutr Rev 65(2):51–62 Eur J Clin Nutr 56(S4):S21–S26 Rumbo M, Anderle P, Didierlaurent A, Sierra F, Debard N, Sirard JC, Pessi T, Sütas Y, Hurme M, Isolauri E (2000) Interleukin-10 generation Finke D, Kraenhenbuhl JP (2004) How the gut link innate and in atopic children following oral Lactobacillus rhamnosus GG. adaptative immunity. Ann N Y Acad Sci 1029:16–21 Clin Exp Allergy 30:1804–1808 Saikali J, Picard C, Freitas M, Holt P (2004) Fermented milks, Pierides M, El-Nezami H, Peltonen K, Salminen S, Ahokas J (2000) probiotic cultures, and colon cancer. Nutr Cancer 49:14–24 Ability of dairy strains of lactic acid bacteria to bind aflatoxin Sartor RB (2004) Therapeutic manipulation of the enteric microflora M1 in a food model. J Food Protect 63:645–650 in inflammatory bowel diseases: antibiotics, probiotics, and Piskula MK (2000) Factors affecting flavonoids absorption. Biofactors prebiotics. Gastroenterology 126(6):1620–1633 12:175–180 Scantlebuy-Manning T, Gibson GR (2004) Prebiotics. Best Pract Res Pompei A, Cordisco L, Amaretti A, Zanoni S, Matteuzzi D, Rossi M Cl Ga 18:287–298 (2007) Folate production by bifidobacteria as a potential pro- Schiffrin EJ, Blum S (2002) Interactions between the microbiota and biotic property. Appl Environ Microbiol 73(1):179–185 the intestinal mucosa. Eur J Clin Nutr 56(3):S60–S64 Pool-Zobel BL (2005) Inulin-type fructans and reduction in colon Servin AL (2004) Antagonistic activities of lactobacilli and cancer risk: review of experimental and human data. Br J Nutr 93 bifidobacteria against microbial pathogens. FEMS Microbiol (S1):S73–S90 Rev 28:405–440 Pool-Zobel BL, Sauer J (2007) Overview of experimental data on Shanahan F (2002) The host–microbe interface within the gut. Best reduction of colorectal cancer risk by inulin-type fructans. J Nutr Pract Res Clin Gastroenterol 16:915–931 137:2580S–2584S Suzuki K, Benno Y, Mitsuoka T, Takebe S, Kobashi K, Hase J (1979) Qin J, Li R, Raes J, Arumugam M, Burgdorf KS, Manichanh C, Urease-producing species of intestinal anaerobes and their Nielsen T, Pons N, Levenez F, Yamada T, Mende DR, Li J, Xu J, activities. Appl Environ Microbiol 37(3):379–382 Li S, Li D, Cao J, Wang B, Liang H, Zheng H, Xie Y, Tap J, Takagi A, Matsuzaki T, Sato M, Nomoto K, Morotomi M, Yokokura T Lepage P, Bertalan M, Batto JM, Hansen T, Le Paslier D, (2001) Enhancement of natural killer cytotoxicity delayed murine 30 Ann Microbiol (2012) 62:15–30 carcinogenesis by a probiotic microorganism. Carcinogenesis Van Nieuwenhove CP, Oliszewski R, González SN, Pérez Chaia AB 22:599–605 (2007) Conjugated linoleic acid conversion by dairy bacteria cultured Takagi A, Ikemura H, Matsuzaki T, Sato M, Nomoto K, Morotomi M, in MRS broth and buffalo milk. Lett Appl Microbiol 44(5):467–474 Yokokura T (2008) Relationship between the in-vitro response of Ventura M, O'Flaherty S, Claesson MJ, Turroni F, Klaenhammer TR, dendritic cells to Lactobacillus and prevention of tumorigenesis van Sinderen D, O'Toole PW (2009) Genome-scale analyses of in the mouse. J Gastroenterol 43:661–669 health-promoting bacteria: probiogenomics. Nat Rev Microbiol 7 Thirabunyanon M (2011) Biotherapy for and protection against (1):61–71 gastrointestinal pathogenic infections via action of probiotic Villena J, Medina M, Vintiñi E, Alvarez S (2008) Stimulation of bacteria. Maejo Int J Sci Technol 5(01):108–128 respiratory immunity by oral administration of Lactococcus Trush MA, Kensler TW (1991) An overview of the relationship lactis. Can J Microbiol 54(8):630–638 between oxidative stress and chemical carcinogenesis. Free Radic Vuillaume M (1987) Reduced oxygen species, mutation, induction and Biol Med 10:201–209 cancer initiation. Mutat Res 186:43–72 Valko M, Leibfritz D, Moncol J, Cronin MTD, Mazur M, Telser J Young GP, Hu Y, Le Leu RK, Nyskohus L (2005) Dietary fibre and (2007) Free radicals and antioxidants in normal physiological colorectal cancer: a model for environment-gene interactions. functions and human disease. Int J Biochem Cell B 39(1):44–84 Mol Nutr Food Res 49:571–584 Van Loo J, Clune Y, Bennet M, Collins JK (2005) The SYNCAN Yu DCW, Waby JS, Chirakkal H, Staton CA, Corfe BM (2010) project: goals, set-up, first results and settings of the human Butyrate suppresses expression of neuropilin I in colorectal cell intervention study. Br J Nutr 93(S1):S91–S98 lines through inhibition of Sp1 transactivation. Mol Cancer 9:276 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Annals of Microbiology Springer Journals http://www.deepdyve.com/lp/springer-journals/role-of-intestinal-microbiota-in-colon-cancer-prevention-zh3QWK8yN4

Loading next page...

References (29)

MO Altonsy, SC Andrews, KM Yuohy (2010)
Differential induction of apoptosis in human colonic carcinoma cells (Caco-2) by Atopobium, and commensal, probiotic and enteropathogenic bacteria: mediation by the mitochondrial pathway
Int J Food Microbiol, 137
SA Bingham, NE Day, R Luben, P Ferrari, N Slimani, T Norat, F Clavel-Chapelon, E Kesse, A Nieters, H Boeing (2003)
Dietary fibre in food and protection against colorectal cancer in the European Prospective Investigation into Cancer and nutrition (EPIC): an observational study
Lancet, 361
B Biavati, M Vescovo, S Torriani, V Bottazzi (2000)
Bifidobacteria: history, ecology, physiology and applications
Ann Microbiol, 50
DJ Bueno, CH Casale, RP Pizzolitto, MA Salvano, G Oliver (2007)
Physical adsorption of aflatoxin B1 by Lactic Acid Bacteria and Saccharomyces cerevisiae: a theoretical model
J Food Protect, 70
H Bernstein, C Bernstein, CM Payne, K Dvorak (2009)
Bile acids as endogenous etiologic agents in gastrointestinal cancer
World J Gastroenterol, 15
DA Barber, SR Harris (1994)
Oxygen free radicals and antioxidants: a review
Am Pharm, 34
MA Belury (2002)
Inhibition of carcinogenesis by conjugated linoleic acid: potential mechanisms of action
J Nutr, 132
JJ Cebra (1999)
Influences of microbiota on intestinal immune system development
Am J Clin Nutr, 69
KE Visser, A Eichten, LM Coussens (2006)
Paradoxical roles of the immune system during cancer development
Nat Rev Cancer, 6
G Capurso, M Marignani, G Delle Fave (2006)
Probiotics and the incidence of colorectal cancer: when evidence is not evident
Digest Liver Dis, 38
M Coakley, S Banni, MC Johnson, S Mills, R Devery, G Fitzgerald, R Paul Ross, C Stanton (2009)
Inhibitory effect of conjugated alpha-linolenic acid from bifidobacteria of intestinal origin on SW480 cancer cells
Lipids, 44
C Giacinto, M Marinaro, M Sanchez, W Strober, M Boirivant (2005)
Probiotics ameliorate recurrent Th1-mediated murine colitis by inducing IL-10 and IL-10-dependent TGF-β-bearing regulatory cells
J Immunol, 174
A Bhattacharya, J Banu, M Rahman, J Causey, G Fernandes (2006)
Biological effects of conjugated linoleic acids in health and disease
J Nutr Biochem, 17
JM Brown, LD Attardi (2005)
The role of apoptosis in cancer development and treatment response
Nat Rev Cancer, 5
WR Bruce, A Giacca, A Medline (2000)
Possible mechanisms relating diet and risk of colon cancer
Cancer Epidemiol Biomarkers Prev, 9
H Bernstein, C Bernstein, CM Payne, K Dvorakova, H Garewal (2005)
Bile acids as carcinogens in human gastrointestinal cancers
Mutat Res, 589
B Biavati, P Mattarelli (2006)
The prokaryotes: a handbook of the biology of bacteria: Bacteria:
SS Choi, Y Kim, KS Han, S You, S Oh, SH Kim (2006)
Effects of Lactobacillus strains on cancer cell proliferation and oxidative stress in vitro
Lett Appl Microbiol, 42
M Ahotupa, M Saxelin, R Korpela (1996)
Antioxidant properties of Lactobacillus GG
Nutr Today Suppl, 31
SJ Duthie (1999)
Folic acid deficiency and cancer: mechanisms of DNA instability
Brit Med Bull, 55
S Blau, A Rubinstein, P Bass, C Singaram, R Kohen (1999)
Differences in the reducing power along the rat GI tract: lower antioxidant capacity of the colon
Mol Cell Biochem, 194
D Commane, R Hughes, C Shortt, I Rowland (2005)
The potential mechanisms involved in the anti-carcinogenic action of probiotics
Mutat Res, 591
J Ballongue (2004)
Lactic acid bacteria. Microbiological and functional aspects
M Coakley, MC Johnson, E McGrath, S Rahman, RP Ross, GF Fitzgerald, R Devery, C Stanton (2006)
Intestinal bifidobacteria that produce trans-9, trans-11 CLA: a fatty acid with anti-proliferative activity against human colon SW480 and HT-29 cancer cells
Nutr Cancer, 56
H Annuk, J Shchepetova, T Kullisaar, E Songisepp, M Zilmer, M Mikelsaar (2003)
Characterization of intestinal lactobacilli as putative probiotic candidates
J Appl Microbiol, 94
E Barrett, RP Ross, GF Fitzgerald, C Stanton (2007)
Rapid screening method for analyzing the conjugated linoleic acid production capabilities of bacterial cultures
Appl Environ Microbiol, 73
L Vuyst, F Leroy (2007)
Bacteriocins from Lactic Acid Bacteria: production, purification, and food applications
J Mol Microbiol Biotechnol, 13
L Alonso, EP Cuesta, SE Gilliland (2003)
Production of free conjugated linoleic acid by Lactobacillus acidophilus and Lactobacillus casei of human intestinal origin
J Dairy Sci, 86
M Coakley, RP Ross, M Nordgren, G Fitzgerald, R Devery, C Stanton (2003)
Conjugated linoleic acid biosynthesis by human-derived Bifidobacterium species
J Appl Microbiol, 94

Publisher: Springer Journals
Copyright: Copyright © 2011 by Springer-Verlag and the University of Milan
Subject: Life Sciences; Microbiology; Microbial Genetics and Genomics; Microbial Ecology; Mycology; Medical Microbiology; Applied Microbiology
ISSN: 1590-4261
eISSN: 1869-2044
DOI: 10.1007/s13213-011-0306-6
Publisher site: See Article on Publisher Site

Abstract

Ann Microbiol (2012) 62:15–30 DOI 10.1007/s13213-011-0306-6 REVIEW ARTICLE Loredana Baffoni & Francesca Gaggìa & Diana Di Gioia & Bruno Biavati Received: 18 February 2011 /Accepted: 21 June 2011 /Published online: 20 July 2011 Springer-Verlag and the University of Milan 2011 Abstract Environmental and hereditary factors, together Intestinal homeostasis relies on the equilibrium between with lifestyle, are important factors in colon cancer absorption (nutrients, ions), secretion (ions, IgA), and the development. Considering the increasing incidence of this barrier capacity of the digestive epithelium towards disease, especially in the developed western world, the last pathogens and macromolecules. These functions are con- decade has seen much attention directed towards under- trolled through multiple interactions with the endocrine, standing possible prevention strategies. Efforts to study the neurocrine, stromal and immune cells and with the resident intestinal microbiota and its interaction with the host have bacterial microbiota that regulates epithelial functions. The underlined that disbiosis in colonic bacterial composition is development and maintenance of a healthy microbiota is a risk factor for colon cancer. Modulation of the composi- extremely important for the correct maturation of the gut tion of intestinal microbiota through the use of probiotic, associated lymphoid tissue (GALT) and the intestinal prebiotic and synbiotic products could therefore represent a mucosa (Macpherson and Harris 2002; Schiffrin and Blum strategy for prevention of cancer development. The mech- 2002; McCracken and Lorenz 2001). anisms underlying the probiotic-prebiotic anticarcinogenic The human microbiota is a complex ecosystem harbour- effect involve a combination of events: e.g. binding of ing more than 1,000 species (Qin et al. 2010) although its mutagens, suppression of bacteria that convert pro- true size and diversity remain largely unknown (Marchesi carcinogens into carcinogens, immune system stimulation, 2010; Hattori and Taylor 2009; Ley et al. 2006). Microbial and a reduction in the level of certain intestinal bacterial colonisation begins immediately after birth with a succes- enzymes that promote carcinogen formation. sion of different species colonising each gastrointestinal (GI) site until an equilibrium is reached (Guarner and . . Keywords Colon cancer Mechanism of prevention Malagelada 2003;O’Hara and Shanahan 2006). Because . . Probiotic Prebiotic Synbiotic intestinal motility is slow, and oxidation-reduction poten- tials are very low, the large intestine is undoubtedly the richest colonisation site in the human body, harbouring a 10 11 Introduction great number of bacteria (10 –10 cfu/g intestinal content) (Hao and Lee 2004), constituted mainly by anaerobes or The intestine constitutes the largest site of interaction facultative anaerobes, including Bacteroides, Peptostrepto- between an individual and the surrounding environment. coccus, Eubacterium, Bifidobacterium, Ruminococcus, Fusobacterium, Clostridium, Lactobacillus, Enterococcus, Enterobacter, Escherichia coli. The colonic microbiota influences a variety of intestinal : : : L. Baffoni (*) F. Gaggìa D. Di Gioia B. Biavati functions and plays a key role in nutrition, in maintaining Department of Agroenvironmental Sciences and Technologies, the integrity of the epithelial barrier, and in the development University of Bologna, of mucosal immunity (Shanahan 2002). Unabsorbed dietary viale Fanin 42, sugars, such as lactose, alcohols and undigested polysac- 40127 Bologna, Italy charides are salvaged by bacterial enzymes, and fermented e-mail: loredana.baffoni@unibo.it 16 Ann Microbiol (2012) 62:15–30 into short-chain fatty acids (SCFAs) that are used as an Early detection and surgery have significantly reduced energy source by the colonic mucosa. SCFAs promote both mortality and morbidity in patients affected by the growth of intestinal epithelial cells and control their colorectal cancer, but survival after surgical treatment for proliferation and differentiation. Moreover, enteric bac- advanced tumour has not seen significant improvements in teria produce valuable vitamins, such as folate, vitamins recent years. Hence, prevention of the development of of B group (B1, B2, B6, B12) and vitamin K colorectal cancer appears to be a more rational and effective (Ballongue 2004). The relationship between the host strategy. The multistep nature of colorectal cancer, together immune system and the indigenous microbiota is impor- with the concept of carcinogenesis (i.e. the phenomenon by tant in protecting the host from pathogen colonisation. In which independent premalignant foci may progress concur- this regard, intestinal bacteria produce a variety of rently and at different rates to give rise to multiple primary substances, ranging from relatively nonspecific acids, tumours), make the colon a peculiarly suitable target organ fatty acids and peroxides, to highly specific bacteriocins for any given chemoprevention study. Indeed, chemo- that can inhibit or kill potentially pathogenic bacteria prevention of colorectal cancer in humans has been the (Servin 2004). focus of a number of studies where fibre, vitamins, calcium, low-fat diet, and non-steroidal anti-inflammatory drugs have all been shown to affect the incidence of this disease. Importance of prevention in colon cancer development Approximately 70% of colorectal cancer is associated with environmental factors, mainly diet (Saikali et al. 2004). Cancer is a combination of various metabolic and physio- Thus, much attention has focused on decreasing cancer risk logic disturbances in the cell that are directly or indirectly through changes in dietary habits, consumption of pro- related to the influence of genetic makeup. Generally, all biotics and increasing intake of dietary fibres (prebiotics). It cancers involve the malfunction of genes that control cell has been reported that ingestion of probiotics, prebiotics, or growth and division. The process by which cancer develops a combination of both (synbiotics) plays an important role is called carcinogenesis. Generally, the carcinogenesis in the prevention of colorectal cancer, and represents a process starts when DNA is damaged by chemicals or novel new therapeutic option (Jain et al. 2009; Le Leu et al. radiation (carcinogen). Viruses are also potent inducers of 2010; Choi et al. 2006). cancer, and usually induce carcinogenesis by introducing new DNA sequences. Normal cells have DNA repair machinery, so that, most of the time, when DNA is Probiotic, prebiotic and synbiotic: a definition damaged the cell is able to repair it. Genetic instability Many definitions have been proposed for the term probiotic. provides a mechanism through which normal cells can accumulate sufficient mutations to become malignant. As originally defined by Fuller, a probiotic is “alive microbial However, cells possess important mechanisms to combat feed supplement which beneficially affects the host health by genomic instability, which is driven by the loss of cell-cycle improving its intestinal microbial balance” (Fuller 1989). The checkpoints, persistent DNA damage or telomere dysfunc- most recent definition provided by FAO-WHO is: “live tion. Central to this mechanism is the tumour-suppressor microorganisms which, when administered in adequate protein p53. The p53 protein is important in transducing amounts, confer a health benefit on the host” (FAO/WHO diverse signals such as a range of stresses (i.e. DNA 2002). Probiotics belong mainly to the genera Lactobacillus damage, hypoxia or proliferative signals) into tumour- and Bifidobacterium (Macfarlane and Cummings 1999; suppressive apoptotic or growth-arresting responses; this Biavati et al. 2000; Biavati and Mattarelli 2006). Potential implies that there is strong selection for tumour cells to lose health benefits deriving from probiotics may vary depending p53 function (Brown and Attardi 2005; Evan and Vousden on the type of probiotic consumed. Probiotic species that can 2001). The exact mechanisms whereby the development of be used in food or pharmaceutical preparations need to have cancer is mediated through mutations are still obscure; Qualified Presumption of Safety (QPS) status. The QPS since carcinogenesis is a multistep process, just how many concept provides a generic assessment system for use within mutations in DNA are required for the development of the the European Food Safety Authority (EFSA) that in principle complete carcinogenesis process remains unknown. As can be applied to all requests received for the safety many as ten distinct mutations may have to accumulate in assessments of microorganisms deliberately introduced into a cell before the cell becomes cancerous (Jain et al. 2009). the food chain. In essence, this proposed that a safety The increasing prevalence of human colorectal cancer assessment of a defined taxonomic group (e.g. genus or is attracting the attention of health professionals and group of related species) could be made based on four researchers seeking more efficacious therapeutic and pillars: establishing identity, body of knowledge, possible prevention strategies. pathogenicity and end use. If the taxonomic group did not Ann Microbiol (2012) 62:15–30 17 raise safety concerns or, if safety concerns existed but could on the other hand applies the Generally Recognized As Safe be excluded through targeted characterisation studies, QPS (GRAS) concept. Both QPS and GRAS share the same core status could be granted. QPS granted microorganisms are values; however, considering the different social and regula- listed in Table 1 (EFSA 2008). The United States Food and tory climate present in Europe, issues of importance to Drug Administration (FDA)—the US equivalent of EFSA— Europe would not necessary influence a GRAS listing. Table 1 List of microorganisms granted Qualified Presumption of Safety (QPS) status (EFSA 2008) (kindly provided by Gaggìa et al. 2010) Gram-positive non-sporulating bacteria Bifidobacterium adolescentis Bifidobacterium animalis Bifidobacterium breve Bifidobacterium bifidum Bifidobacterium longum Corynebacterium glutamicum Lactobacillus acidophilus Lactobacillus delbrueckii Lactobacillus panis Lactobacillus amylolyticus Lactobacillus farciminis Lactobacillus paracasei Lactobacillus amylovorus Lactobacillus fermentum Lactobacillus paraplantarum Lactobacillus alimentarius Lactobacillus gallinarum Lactobacillus pentosus Lactobacillus aviaries Lactobacillus gasseri Lactobacillus plantarum Lactobacillus brevis Lactobacillus helveticus Lactobacillus pontis Lactobacillus buchneri Lactobacillus hilgardii Lactobacillus reuteri Lactobacillus casei Lactobacillus johnsonii Lactobacillus rhamnosus Lactobacillus coryniformis Lactobacillus kefiranofaciens Lactobacillus sakei Lactobacillus crispatus Lactobacillus kefiri Lactobacillus salivarius Lactobacillus curvatus Lactobacillus mucosae Lactobacillus sanfranciscensis Lactococcus lactis Leuconostoc citreum Leuconostoc lactis Leuconostoc mesenteroides Pediococcus acidilactici Pediococcus dextrinicus Pediococcus pentosaceus Propionibacterium freudenreichii Streptococcus thermophilus Gram-positive sporulating bacteria Bacillus amyloliquefaciens Bacillus atrophaeus Bacillus lentus Bacillus pumilus Bacillus clausii Bacillus licheniformis Bacillus subtilis Bacillus coagulans Bacillus megaterium Bacillus vallismortis Bacillus fusiformis Bacillus mojavensis Geobacillus stearothermophillus Yeast Debaryomyces hansenii Hanseniaspora uvarum Kluyveromyces lactis Kluyveromyces marxianus Pichia angusta Pichia jadinii Pichia anomala Pichia pastoris Saccharomyces bayanus Saccharomyces pastorianus (synonym Saccharomyces carlsbergensis) Saccharomyces cerevisiae Schizosaccharomyces pombe Xanthophyllomyces dendrorhous 18 Ann Microbiol (2012) 62:15–30 Prebiotic compounds are defined as “non-digestible food Ochratoxin A (OTA), a toxin produced by Aspergillus ingredients that beneficially affect the host by selectively ochraceus and Penicillium verrucosum, is one of the most stimulating the growth and/or activity of one or a limited abundant food-contaminating mycotoxins in the world. number of bacteria in the colon” (Gibson and Roberfroid Fumonisins are a family of toxins produced by several species 1995). For a dietary substrate to be classified as a prebiotic, of Fusarium moulds, which occur mainly in maize, wheat at least three criteria are required: (1) the substrate must not and other cereals. Aflatoxins, OTA and fumonisins are be hydrolyzed or absorbed in the stomach or small considered carcinogens by the World Health Organization intestine; (2) it must be selective for beneficial commensal International Agency for Research on Cancer (IARC 1993). bacteria, such as the bifidobacteria, in the large intestine; (3) Many studies have investigated the binding of aflatoxins fermentation of the substrate should induce beneficial luminal/ to lactic acid and probiotic bacteria (Fazeli et al. 2009; systemic effects within the host (Scantlebuy-Manning and Bueno et al. 2007; Haskard et al. 2001). The binding of the Gibson 2004). Dietary modulation of the human gut micro- toxin is strain-dependent and is reversible in nature (Fazeli biota with prebiotics has been investigated for many years to et al. 2009; Haskard et al. 2001). Some researchers have improve gut microbial balance (Hord 2008; Roberfroid suggested that aflatoxin molecules bind cell wall compo- 2007; Rastall et al. 2005). nents of the bacteria (Hernandez-Mendoza et al. 2009; Synbiotics may be defined as mixtures of probiotics and Haskard et al. 2001), but cell surface hydrophobicity may prebiotics that beneficially affect the host by improving the also play an important role (Oatley et al. 2000). Lahtinen et survival and implantation of live microbial dietary supple- al. (2004) stressed that cell wall polysaccharides and ments in the gastrointestinal tract (Gibson and Roberfroid peptidoglycan may be the most important elements respon- 1995). Roberfroid (1998) suggested that a combination of sible for the binding mechanism. Some experiments also prebiotics and probiotics might be more active on the colon reveal that heat treatment of bacterial cells improves their than the individual components alone. The effectiveness of ability to remove aflatoxins AFM1 and AFB1, possibly due a synbiotic formula is, however, strictly dependent on the to the formation of Maillard reaction products between probiotic strain properties and its fermentation ability polysaccharides, peptides, and proteins (El-Nezami et al. towards the selected prebiotic compound. 2002; Pierides et al. 2000). In contrast, research by El- Nezami and coworkers (1998a) showed that heat-treated dairy strains of LAB seem to have the same ability to Mechanisms underlying cancer prevention remove AFB1 as viable bacteria, indicating that viability may not be an essential prerequisite. Polarity of the toxins The anti-carcinogenic properties of probiotic bacteria are also plays an important role in the binding mechanism. The percentage of aflatoxin removed by dairy strains of LAB probably linked to multiple activities: (1) carcinogen binding, (2) modulation of the other intestinal bacteria and bifidobacteria decreases in the order: AFB1 > AFB2 > enzymes, (3) effects on oxidative stress, (4) production of AFG1 > AFG2, which is correlated with the decreasing beneficial compounds, (5) immune modulation, and (6) polarity of these toxins and is consistent with hydrophobic apoptotic deletion. interactions, suggesting the involvement of the latter in the binding mechanism (Haskard et al. 2000). Another critical Binding/absorption of carcinogens factor, as reported by El-Nezami et al. (1998b), is the size of the bacterial population involved in aflatoxin binding; it is Studies confirm that some strains of lactic acid bacteria (LAB) estimated that a minimum of approximately 2 x 10 CFU/ml are able to bind food carcinogens (e.g. mycotoxins or is required for significant AFB1 removal. The same amount heterocyclic aromatic amines present in cooked meat and seems to be necessary for binding of OTA (Fuchs et al. fish), excluding them from the human gut and reducing 2008) by strains of Lactobacillus, Propionibacterium and thereby the rate of exposure to these highly toxic compounds. Bifidobacterium (Kabak and Dobson 2009). Aflatoxins are naturally occurring mycotoxins and are Studies also indicate that probiotic bacteria can bind among the most carcinogenic substances known, being other toxic compounds, e.g. toxic secondary bile acids metabolized by the liver to a reactive epoxide intermediate. produced by the metabolic activity of some intestinal Aflatoxin B (AFB1) is considered the most toxic and is bacteria (see next section). produced by Aspergillus flavus and Aspergillus parasiticus, which also produce aflatoxin B (AFB2). Aflatoxins G and Modulation of intestinal bacteria enzymes 2 1 G (AFG1 and AFG2) are produced by Aspergillus para- siticus. Aflatoxin M (AFM1) was discovered in the milk of In addition to the aforementioned binding mechanisms, cows fed with mouldy grain and is produced following a probiotic microorganisms could play a role in the preven- conversion process of aflatoxin B in the animal’s liver. tion of the initiation phase of carcinogenesis by decreasing 1 Ann Microbiol (2012) 62:15–30 19 exposure to activated faecal carcinogens. Animal and human bile acids are secreted into the duodenum in the form of studies with Lactobacillus and Bifidobacterium supplements conjugates, which are degraded by bacterial enzymes in show a drop in detrimental faecal enzyme concentrations the large intestine and transformed to deconjugated or such as nitroreductase, β-glucuronidase, azoreductase, 7α- secondary bile acids that are toxic. A high dietary intake dehydroxylase and urease (Kumar et al. 2010). It is well of fat and red meat results in a significantly higher known that these enzymes, which are present in some excretion of faecal secondary bile acids (Reddy et al. intestinal bacteria, are able to convert pro-carcinogen 1980; Bernstein et al. 2009) and conjugated bile acids compounds into carcinogens in the human colon. seem to enhance excretion of β-glucuronidase from, for Nitroreductases from bacteria are oxygen-insensitive and example, E. coli and C. perfringens. catalyse the reduction of nitro-compounds, producing Azo dye compounds represent a large group of chem- nitroso, hydroxylamine, and/or amino derivatives. These icals that are used extensively in the textile, pharmaceutical, nitroreductases have been studied in a number of bacteria food, and cosmetic industries. Although the commonly including enterobacteria (e.g. Escherichia coli, Salmonella used azo dyes are not mutagenic in the standard Ames plate typhimurium, Enterobacter cloacae), and exhibit varying assay, they are reduced by azoreductases from intestinal substrate specificities, being able to reduce a wide range of bacteria and, to a lesser extent, by enzymes of the cytosolic nitroaromatics such as nitrophenols, nitrobenzenes, and and microsomal fractions of the liver. Some intestinal nitrobenzoates. A large number of nitroaromatics are bacteria that contain azoreductase belong to the following present in the environment because of their use in genera: Bacteroides spp. (B. fragilis, B. thetaiotaomicron, manufacturing processes and as antimicrobial agents, and B. ovatus and B. vulgatus), Eubacterium spp. (e.g. E. they are also generated as by-products of combustion hadrum) (Rafii et al. 1990), Clostridium spp. (e.g. C. processes. Nitroaromatic compounds have caused consid- leptum, C. paraputrificum, C. clostridiiforme, C. perfrin- erable health concern because their metabolism through gens, C. sporogenes, C. septicum,and C. butyricum) reductive pathways may lead to potent genotoxic and/or (McBain and Macfarlane 1998), Butyrivibrio. Azo dye mutagenic metabolites. Thus, enzymatic reduction by compounds are linked to bladder cancer in humans and to nitroreductases gives rise to reactive intermediates that can hepatocarcinoma and nuclear anomalies in intestinal epi- undergo nucleophilic additions with DNA and other macro- thelial cells in mice. Thus, a number of azo dyes are molecules, suggesting a possible mechanism for their classified as carcinogenic (Rafii et al. 1990). cytotoxicity (Guillén et al. 2009). Some species of the 7α-Dehydroxylase is a detrimental enzyme responsible following genera encode nitroreductases: Clostridium for producing harmful secondary bile acids that exert a spp. (e.g. C. leptum, C. paraputrificum, C. clostridiiforme, cytotoxic effect towards epithelial cells. This enzyme C. perfringens, C. septicum, C. sporogenes and C. removes the 7-alpha hydroxyl group in bile acids. The butyricum), Bacteroides spp. (B. fragilis, B. thetaiotaomi- dehydroxylation of chenodeoxycholic acid leads to the cron, B. ovatus and B. vulgatus) (McBain and Macfarlane formation of lithocholic acid (litho = stone), which is 1998). poorly water-soluble and toxic to cells, producing DNA Intestinal β-glucuronidase may be involved in the breaks (Bernstein et al. 2005). Bile acids formed by development of large bowel cancer. The activity of β- synthesis in the liver are termed “primary” bile acids, glucuronidase in faecal samples or colon contents is and those made by bacteria are termed “secondary” bile increased by high fat diets. Genotoxic and carcinogenic acids (Commane et al. 2005). heterocyclic aromatic amines (HHAs), e.g. 2-amino-3- Urease is en enzyme that breaks the C–N linkage of urea methylimidazo[4,5-f]quinoline (IQ), are formed in meat to form CO ,NH and H O. Urease-producing bacteria 2 3 2 and fish during cooking. Following absorption in the upper inhabiting the GI tract are important in both their nutritional part of the gastrointestinal tract, IQ is metabolized mainly and pathological aspects because they are involved in in the liver by xenobiotic-metabolising enzymes. Among nitrogen recycling, and the resulting product, ammonia, can them, UDP-glucuronosyl transferases lead to harmless be harmful to host health. The following species of glucuronidated derivatives that are partly excreted via the anaerobes include urease-producing strains: Bacteroides bile into the digestive lumen, where they come into contact multiacidus (now: Mitsuokella multiacida), Clostridium with the resident microbiota. β-glucuronidase could con- symbiosum, Eubacterium aerofaciens (now: Collinsella tribute to IQ genotoxicity by releasing reactive intermedi- aerofaciens), Eubacterium lentum (now: Eggerthella lenta), ates from IQ glucuronides (Humblot et al. 2007). This Fusobacterium necrophorum, Fusobacterium varium, Pep- enzyme activity is reported to be present in some intestinal tococcus asaccharolyticus (now: Peptoniphilus asacchar- bacteria such as E. coli, Peptostreptococcus, Bacteroides olyticus), Peptococcus prevotii (now: Anaerococcus (e.g. B. fragilis, B. thetaiotaomicron)and C. perfringens. prevotii), and Peptostreptococcus productus (now: Blautia Faecal bile acid excretion is also increased by a fatty diet; producta) (Suzuki et al. 1979). 20 Ann Microbiol (2012) 62:15–30 Effects on oxidative stress idative activity, inhibiting linoleic acid peroxidation by 28–48% and also show the ability to scavenge the α- Oxidative stress results when the balance between the diphenyl-β-picrylhydrazyl free radical, scavenging 21– production of ROS (reactive oxygen species) overrides the 52%. The intact cells of these two intestinal bacteria antioxidant capability of the target cell. ROS may interact demonstrate a high inhibitory effect on the cytotoxicity of with and modify cellular protein, lipid, and DNA, which 4-nitroquinoline-N-oxide (4NQO, a quinoline derivative results in altered target cell function. The accumulation of and tumorigenic compound). The cytotoxicity of 4NQO is oxidative damage has been implicated in both acute and reduced by approximately one-half by L. acidophilus and chronic cell injury, including participation in the formation by almost 90% by B. longum. Nevertheless, no inhibition of of cancer (Halliwell 2007). ROS can be produced both cytoxicity is observed for intracellular cell-free extracts of endogenously and exogenously. Endogenous oxidative 10 cells of B. longum and L. acidophilus. Pediococcus stress can be the result of normal cellular metabolism and pentosaceus 16:1 and Lactobacillus plantarum 2592 pro- oxidative phosphorylation. The metabolism of substances duce antioxidants after 18 h growth corresponding to by the P450 enzyme system generates oxygen free radicals 100 μg vitamin C, Lactobacillus paracasei F19 a slightly through normal or futile cycling mechanisms (Parke and lower amount, and yet another, L. paracasei, does not exert Ioannides 1990). Exogenous sources of ROS can also any antioxidative activity, again emphasizing that these impact on the overall oxidative status of a cell. Drugs, characteristics are strain-dependent (Kruszewska et al. hormones, and other xenobiotic chemicals can produce 2002). In another study, obligatory homofermentative ROS by either direct or indirect mechanisms (Trush and lactobacilli display high antioxidant activity whereas this Kensler 1991; Halliwell 1996). Alternatively, oxidative property is highly strain-dependent among facultative and stress can also occur when a decrease in the antioxidant obligate heterofermentative lactobacilli (Annuk et al. 2003; capacity of a cell occurs. Non-enzymatic antioxidant levels Kumar et al. 2010). [vitamin E, vitamin C, glutathione (GSH), etc.] and enzymatic antioxidant levels (superoxide dismutase, GSH Production of beneficial compounds peroxidase, and catalase) in the cell can be decreased through modification in gene expression, reduced uptake in Bacterial fermentation in the colonic lumen produces a the diet, or can be overloaded in ROS production, which variety of short chain fatty acid (SCFA) metabolites (e.g. creates a net increase in the amount of oxygen free radicals acetate, butyrate, propionate) that are potential anti- present in the cell (Vuillaume 1987; Barber and Harris carcinogenic agents within the gut. Butyrate has been 1994). Several human chronic disease states (e.g. cirrhosis, implicated in cellular homeostasis of the normal colonic atherosclerosis etc.), including cancer, are associated with mucosa, and this is thought to be one of the mechanisms of oxidative stress (Valko et al. 2007). Some lactobacilli the chemoprotective effect of fibre. In vitro studies indicate possess antioxidative activity, and are able to decrease the that butyrate causes cell cycle arrest, differentiation or risk of accumulation of ROS during the ingestion of food. apoptosis in a number of transformed cell lines (Yu et al. In fact, ROS are produced during passage of nutrients 2010; Bingham et al. 2003). Femia et al. (2002) stress the through the GI tract, and the natural production of host importance of oligofructose administration, alone or to- antioxidants decreases rostrally (Blau et al. 1999, Bruce et gether with probiotic microorganisms, to increase SCFA in al., 2000). LAB are able to degrade the superoxide anion the colon, and decreases the incidence of tumour develop- and hydrogen peroxide. However, the type of superoxide ment in a rat model. dismutase (SOD) expressed in antioxidative strains has not Moreover, the production of SCFA and other organic been assessed. It remains an open question if the anti- acids by LAB and probiotics reduces intestinal pH, oxidative potency of strains is associated with their survival preventing thereby the growth of putrefactive bacteria and in stressful environments. Kullisaar et al. (2002) reported pathogens and modulating detrimental enzymes that acti- that two strains of Lactobacillus fermentum with substantial vate toxic metabolites (see section above on Modulation of antioxidative activity, express Mn-SOD (manganese-super- intestinal bacteria enzymes) (Servin 2004). A prebiotic/ oxide dismutase) and have significantly increased resistance probiotic-induced decrease in luminal colonic pH may to several ROS such as hydrogen peroxide, superoxide and function to improve mineral solubility and uptake, namely, hydroxyl radicals. LGG and LGG-fermented milk are calcium, magnesium, and iron. The availability of minerals demonstrated to be potent scavengers of superoxide anion is also enhanced through bacterial fermentation of sub- and inhibitors of lipid peroxidation reactions in vitro stances such as phytate (myoinositol hexaphosphate), (Ahotupa et al. 1996). Lin and Chang (2000) show that a which remove divalent cations. In particular, calcium is strain of Bifidobacterium longum ATCC 15708 and a strain suggested to be beneficial toward colorectal cancer, with of Lactobacillus acidophilus ATCC 4356 display antiox- increasing evidence that it inhibits proliferation and Ann Microbiol (2012) 62:15–30 21 enhances differentiation and apoptosis of mucosal cells Numerous researchers report that LAB also have the (Lamprecht and Lipkins 2003; Jain et al. 2009). ability to synthesise folate, for example industrial starter Some probiotic strains also produce molecules with bacteria Lactococcus lactis, Streptococcus thermophilus, antagonistic activity against intestinal pathogens called and Leuconostoc species and some probiotic strains (e.g. bacteriocins. Bacteriocins are a heterogeneous group of bifidobacteria, lactobacilli, propionibacteria, and Saccharo- ribosomally synthesized peptides or proteins displaying myces cerevisiae) (Iyer and Tomar 2009; Pompei et al. antimicrobial activity against other bacteria. LAB bacter- 2007). Folic acid, one of the B vitamins (B9), acts as iocins seem to be targeted primarily to other LAB, which cofactor in numerous biochemical reactions through its are likely to be the most prominent competitor in the ability to donate or accept one-carbon units. Mammals are (acidic) ecological niche in which these bacteria reside. unable to synthesise folic acid de novo and so they must However, LAB bacteriocins also show activity towards a obtain it either from the diet or from microbial breakdown number of potential Gram-positive food spoilage and/or in the gut. Folate deficiency induces cytogenetic damage pathogenic bacteria, for example towards Listeria. LAB are and mutations both in vivo and in vitro, with increases in GRAS and so are their bacteriocins, which do not affect DNA strand breakage, chromosomal aberrations and micro- humans or other eukaryotes. Bacteriocins are thus receiving nuclei formation (Duthie 1999). A number of reviews have great attention, since applications as ‘natural’ food preser- focussed on the health benefits associated with increased vatives, and maybe even as antibiotics, may be envisaged. folate intake, and many countries possess mandatory folate Since about 1990, this field has grown dramatically and this enrichment programs. Lately, a number of studies have has led to the discovery and characterisation of a large shown that high intakes of chemically synthesized folic number of bacteriocins (García et al. 2010; De Vuyst and acid, but not natural folates, can cause adverse effects in Leroy 2007). some individuals, such as the masking of the haematolog- Conjugated linoleic acids (CLA) are a family of ical manifestations of vitamin B12 deficiency, leukaemia, positional and geometric isomers of linoleic acid that have arthritis, bowel cancer, and ectopic pregnancies. Fermented been associated with several health benefits. Different milk products are reported to contain high amounts of folate bacteria have been identified as capable of synthesizing produced by food-grade bacteria, primarily LAB. The focus CLA. These include both probiotic strains and dairy starter has therefore shifted toward natural folate, i.e. folate cultures as well as strains of human intestinal origin (Mills produced by LAB, and levels of folate present in foods et al. 2009; Alonso et al. 2003; Barrett et al. 2007; Coakley fermented by, or containing, these valuable microorganisms. et al. 2006; Ewaschuk et al. 2006, Coakley et al. 2003). The proper selection and use of folate-producing micro- Several works report the ability of Bifidobacterium spp. organisms is an interesting strategy to increase “natural” folate levels in foods (Iyer and Tomar 2009). to convert LA into CLA (Van Nieuwenhove et al. 2007; Barrett et al. 2007; Ewaschuk et al. 2006; Coakley et al. Dietary flavonoids, a class of semi-essential food 2009; Rodríguez-Alcalá et al. 2011). B. breve is considered components, have long been believed to exert protective the most efficient CLA-producing species, with conversion effects against many diseases, in particular cardiovascular rates up to 65% following 48 h fermentation (Coakley et al. disease and cancer. This has been well supported by myriad 2003, 2009). However, some strains of B. breve display a studies examining potential sites and modes of action. low conversion rate (Barrett et al. 2007), thus suggesting a There has been a proliferation of mechanistic studies, strain-specific behaviour. B. breve and B. longum from concerning mainly effects on cell signalling pathways. human faecal samples demonstrate conversion rates of up However, these studies are focused entirely on the to 75% following 48 h fermentation of linoleic acid to c9, flavonoid aglycones, not the glycosides—the flavonoid t11 CLA (Barrett et al. 2007). The dairy starters Lacto- forms present in the human diet. Studies have confirmed coccus lactis and Streptococcus thermophilus also exhibit that glycoside hydrolysis is necessary prior to absorption CLA-producing activity (Lin et al. 1999)aswellasthe (Piskula 2000), and that this is accomplished by the β- strain Pediococcus acidilactici (Kishino et al. 2002). The glucosidase enzyme. This enzyme is produced by different isomers cis-9, trans-11 (c9, t11) and trans-10, cis-12 (t10, strains of probiotic bacteria and this could be an advantage c12), have demonstrated exceptional abilities in vitro, and since it may help the release of flavonoids in the large in some cases in vivo, to prevent various types of cancer bowel (Kumar et al. 2010; Marotti et al. 2007). (Belury 2002; Bhattacharya et al. 2006;Kelleyet al. 2007), hypertension, atherosclerosis, obesity, and diabetes, Immune system stimulation as well as an ability to improve immune function, bone formation-promoting properties and to reduce total body The influence of the resident microbiota on mucosal fat composition (Bhattacharya et al. 2006; Nagao and immune function and gut health has become an area of scientific and clinical importance (Fuller 1991; Cebra 1999; Yanagita 2005). 22 Ann Microbiol (2012) 62:15–30 Lee 2009). There is an active dialogue between the switching in human B cells (He et al. 2007). The IgA B commensal microbiota and the host mucosal immune cells induced in Peyer’s patches circulate through the system (Macpherson and Harris 2002). This cross-talk mesenteric lymphatic nodes to enter the blood via the elicits different host responses to commensal and patho- thoracic duct and return to the intestinal mucosa, repopulat- genic bacteria. The healthy host is able to elicit a good ing distant mucosal sites such as the bronchus. Some mucosal immune response against luminal antigens and to probiotic microorganisms are also able to increase the IgA maintain a “physiological state of inflammation” in the gut, cycle, in a dose-dependent manner (Villena et al. 2008; but is also able to face up to invading commensal Perdigon et al. 1999). T-independent IgA induction is also organisms and pathogens. In the healthy host, penetration demonstrated; cytokines, including transforming growth of the commensal bacteria is usually prevented by the factor β (TGF- β), interleukin-4 (IL-4), and IL-2, IL-6, barrier afforded by the intestinal epithelium and the and IL-10, work in a synergistic way with immune cells immune cells associated with the mucosa, which are highly other than T cells and can promote the switch from IgM to adapted to the presence of the normal microbiota. The IgA expression (He et al. 2007). Stimulation with probiotic functioning of the gut mucosal immune system requires a bacteria induces signals on epithelial and immune cells that complex network of signals, with multiple interactions evoke different patterns of cytokines in the intestine between commensals, foreign antigens and eukaryotic cells. (Perdigón et al. 2002;O’Flaherty et al. 2010), depending These include epithelial cells, macrophages, dendritic cells, on thedoseandthestrainadministered. Maldonado and cells belonging to the non-specific barriers: mucus- Galdeano et al. (2007), analysing the profile of cytokines producing cells such as goblet cells, and Paneth cells, induced by some LAB, observe that the most remarkable which secrete antimicrobial peptides (Rook and Brunet effect for all the probiotic strains tested is the increase in 2005). Three different routes exist for the uptake of luminal tumour necrosis factor-alpha (TNF-α), gamma-interferon antigens: dendritic cells, specialized M cells from the (IFN-γ) and of the regulatory cytokine IL-10. This effect is Peyer’s patches, and individual M cells found in the villous obtained without increasing the inflammatory response. epithelium (Mowat 2003;Neutraetal. 1996). The Induction of TNF-α by probiotic bacteria would be anatomical location of the immune cells from the innate necessary to initiate cross-talk between the immune cells response (macrophages and dendritic cells), and the way in associated with the lamina propria and the intestinal which these cells acquire antigens, are crucial in determining epithelial cells, while IFN- γ would play a physiological the nature of the subsequent responses. In the gut immune role. It has been demonstrated that this cytokine is response induced by commensal bacteria, the antigen necessary for the maturation of some immune cells, such presentation from the luminal microbiota leads to the as dendritic cells, and also controls their cellular prolifer- generation of large quantities of local immunoglobulin A ation at the intestinal level (Rumbo et al. 2004). It could be (IgA) without induction of systemic immunity (Macpherson postulated that probiotics (as whole cells or as antigenic and Slack 2007). fragments) interact with the M cells in Peyer’s patches, with In this complex cross-talk between commensal micro- gut epithelial cells, and with the associated immune cells. biota and the intestinal immune system, how can probiotics Following interaction with these cells, the release of affect gut mucosal immunity? It is obvious that these non- cytokines is induced to up- or down-regulate the immune pathogenic bacteria must interact with the epithelial cells response. This may depend if the induction occurs in a and with the immune cells associated with the gut in order physiological state or during pathological processes such as to trigger the network of immune signals. The increase in allergy (Pessi et al. 2000; Özdemir 2010), inflammatory the number of IgA-producing cells is the most remarkable bowel disease (Sartor 2004), or colon cancer (Rafter et al. property induced by probiotic microorganisms or by milk 2007; Takagi et al. 2001; Ewaschuk et al. 2006; Marotta et fermented with LAB (Park et al. 2002; LeBlanc et al. al. 2003), in order to maintain or try to re-establish 2002). IgAs play a critical role in mucosal immunity. In its intestinal homeostasis. Regarding this point, Maldonado secretory form, IgA is the main immunoglobulin found in Galdeano et al. (2007) suggest that, under physiological mucous secretions, including tears, saliva, colostrum and conditions, probiotic bacteria can act as mucosal and secretions from the genito-urinary tract, gastrointestinal systemic adjuvants. tract, prostate and respiratory epithelium. Within the two Under pathological states, such as colon cancer or IgA subclasses (IgA and IgA ) in humans, IgA is intestinal chronic inflammations, probiotics may inhibit 1 2 1 produced preferentially in nasal and bronchial mucosa, disease via modulation of the mucosal and systemic and IgA is produced predominately in the gut. IgA is immune response and by reduction of the inflammatory 2 2 more resistant to pathogen proteases and is present at the response to host microbiota. It has been shown that highest levels in the distal intestine, which has the heaviest intestinal inflammation is linked to the development of colorectal cancer (de Visser et al. 2006); for this purpose, bacterial load. Commensal bacteria promote IgA class 2 Ann Microbiol (2012) 62:15–30 23 some studies evidence the importance of probiotic or gens (Brown and Attardi 2005). Up-regulation or facilita- synbiotic supplementation since an increase in the produc- tion of apoptosis during initiation events might increase the tion of IL-10 (an anti-inflammatory cytokine) has been elimination of mutated cells that might otherwise progress observed (Pessi et al. 2000; Di Giacinto et al. 2005; Madsen to malignancy. Such an effect might be one of the et al. 2001). Intestinal inflammation may also result from mechanisms by which prebiotics and/or probiotics act to exposure to toxic factors such as asbestos or smoke, as well protect against colorectal cancer. Le Leu et al. (2005) as from ongoing chemical or physical irritation [acid-reflux registered a significant apoptotic response to a genotoxic disease, exposure to ultraviolet (UV) light]. Mutation and/ carcinogen in the distal colon of rats using a synbiotic or genetic polymorphism in crucial genes that regulate combination of resistant starch and Bifidobacterium ani- cytokine function, metabolism and leukocyte survival have malis subsp. lactis. A possible mechanism by which also been implicated as aetiological factors in chronic probiotic bacteria may induce apoptotic deletion could be inflammation. During acute inflammation, innate immune through their immunomodulating properties. Cytokines cells form the first line of immune defence and regulate such as TNF-α are capable of inducing apoptosis. Although activation of adaptive immune responses. Conversely, during cytokine levels were not measured by Le Leu et al. (2005), chronic inflammation, these roles can be reversed—adaptive other studies show that the levels of TNF-α, interferon-γ immune responses can cause ongoing and excessive activa- and interleukin-10 may be increased by probiotic supple- tion of innate immune cells (de Visser et al. 2006). Probiotic mentation (Jiang et al. 2009; Lee et al. 2008). Lan et al. bacteria can modulate this over-response. (2008) reported increased induction of apoptosis by Another possible mechanism of carcinogenesis preven- Propionibacterium freudenreichii TL133 in colonic muco- tion is the activation of natural killer (NK) cells. NK cells are sal crypts of human microbiota-associated (HMA) rats large granular lymphocytes derived from bone marrow, and treated with DMH (1,2-dimethylhydrazine). HMA rats con- these cells display non-MHC-restricted cytotoxicity against stitute a well-validated model for experimental studies, aimed a variety of tumours, in part by producing mediators with at evaluating the effects of functional foods and probiotics in anti-angiogenic properties (de Visser et al. 2006). It is well GI physiology. The induction of apoptosis occurs only in recognized that NK cells act as cytolytic effector cells of the animals treated with DMH, suggesting that it specifically innate immune system. Oral feeding of Lactobacillus casei targets damaged cells. The authors suggest that daily Shirota (LcS) to MC-treated mice rendered their NK cells administration of P. freudenreichii may help in the elimination tumouricidal in terms of both quality and quantity, resulting of damaged cells by apoptosis within the colon epithelium. in the suppression of tumour incidence (Takagi et al. 2001). This protective role against colon cancer should be further Yet another possible mechanism of action may involve confirmed by long-term in vivo carcinogenesis assays in dendritic cells. Dendritic cells, as previously highlighted, are order to evaluate their effect on colorectal tumour incidence. thought to be one of the most important types of cells involved Altonsy et al. (2010) compared the role of pathogenic in the presentation of several antigens and in the production of bacteria, probiotic and commensal bacteria on the induction cytokines. Recent studies show Lactobacillus strain-specific of apoptosis in Caco-2 cells in vitro. The results show how activity in prevention of murine tumorigenesis and in the two probiotic strains studied (Lactobacillus rhamnosus induction of IL-12 release by bone marrow-derived dendritic LGG and B. animalis subsp. lactis Bb12) are able to induce cells in vitro (Takagi et al. 2008). Recently, Matsumoto et al. the apoptotic pathway, albeit to a lesser extent compared to (2009) described the role of the LAB strain LcS in pathogenic bacteria (EPEC, VTEC), via the mitochondrial prevention of colon cancer by targeting the immune system. route rather than through the Fas receptor pathway. It is Using a mouse model, they report that L. casei produces a possible that the weak apoptotic effects induced by these polysaccharide that inhibits colon carcinogenesis by sup- strains may be important in driving turnover of the pressing synthesis of IL-6 and signal transducer and activator intestinal epithelium, which could reduce accumulation of of transcription 3 (STAT3) (Kumar et al. 2010). Usually, IL-6 mutations in long-lived epithelial cells. induces phosphorylation of STAT3, which mediates the expression of a variety of genes and plays a key role in Putative molecular mechanisms responsible for colon many cellular processes such as cell growth and apoptosis. cancer reduction by probiotic bacteria Apoptotic deletion The mechanisms by which probiotics affect human health beneficially can be divided into different categories, as Apoptosis is an important innate regulatory process in the delineated in the previous paragraphs, including: strength- protection against the development of cancer. Apoptosis ening of the intestinal barrier, modulation of the immune leads to the removal of cells with genomic instability response, antagonism of pathogens. The molecular details caused by tumor development or by exposure to carcino- behind these mechanisms are now being investigated 24 Ann Microbiol (2012) 62:15–30 through genomics-based approaches to identify the relevant – Some probiotic strains induce expression of the molecular interaction between probiotics and host cells both antimicrobial peptide β-defensin-2 (hBD-2). β defen- in vitro and in vivo. sins are small antimicrobial peptides of the innate immune system produced in response to microbial – Probiotic microorganisms may interact directly with infection of mucosal tissue and skin; among the dendritic cells (DCs). As already illustrated in the defensin family the β-type is distributed most widely, section above on Immune system stimulation, DCs being secreted by leukocytes and epithelial cells of intervene in early bacterial recognition and consequently many kinds. Activation of hBD-2 might lead to the have a role in shaping T-cell responses. Several probiotic enhancement of the barrier effect of the intestinal species have been shown to induce the in vitro maturation mucosa and could explain, at least in part, the ability and cytokine expression of DCs. It seems that Lactoba- of specific probiotics to inhibit pathogen growth in the cillus–DC interactions are mediated by the bacterium gut (Marco et al. 2006). binding to the dendritic lectin (DC-SIGN). Lactobacillus – There is also evidence that probiotics can modulate strains that are able to interact with this lectin led to the MUC gene expression. Mucins are a family of large, development of populations of regulatory T-cells that heavily glycosylated proteins. Some mucins are produce interleukin-10. They can also induce hypores- membrane-bound while others are secreted on mucosal ponsive CD4 T-cell populations. surfaces and play an important role in maintaining – Probiotic microorganisms could be recognized by mucosal barriers. MUC genes encode mucin monomers intestinal epithelial cells (IEC) or colon epithelial cells that are post-translationally modified by exceptionally (CEC) through interaction between Toll-like receptors abundant glycosylation. The increased expression of (TLRs) and bacterial components. The signal thus certain specific MUC genes instead of others may produced arrives in the nucleus through a signal create a highly difficult situation for pathogen binding. transduction pathway that can modulate gene expres- The anti-pathogenic activities (Britton and Versalovic sion of different cytokines. 2008; Thirabunyanon 2011) of probiotics have already been – Modulation of inflammatory responses may also be mentioned; mechanisms of pathogen load reduction are effected through inactivation of the NF-κB signalling briefly summarised below: pathway; there are two possible mechanisms for this. – competitive exclusion (CE): adhesin-mediated attach- Soluble components produced by probiotic bacteria are ment of probiotics excludes pathogens; recognized by IEC, leading to inhibition of protea- – aggregation: probiotics aggregate with pathogens, somes, and consequently to inhibition of the transcrip- leading to expulsion from the gut; tion factor NF-κB. The proteasome is in fact a protein – nutrient competition: probiotics compete with patho- complex whose main function is to degrade unneeded gens for essential nutrients; or damaged proteins by proteolysis. This complex – masking: masking of intestinal receptors for enter- usually degrades NF- κB inhibitor (I-κB), enabling otoxins binding by probiotic adhesins; NF-κB to access the nucleus. If I-κB is not degraded, – production of antimicrobial substances: probiotics it can bind to NF-κB and inhibit its translocation produce hydrogen peroxide (H O ), bacteriocins (e.g. across the nuclear membrane. Another way to inhibit 2 2 lactocins, helveticins, lactacins, curvacins, nisin, bifi- NF-κB is through interaction of bacterial CpG DNA docin) and organic acids, the latter lowering pH, create with TLR9; the result is, again, the prevention of I-κB a forbidding environment for a wide range of harmful degradation. microorganisms. Other mechanisms have also been suggested to explain It is probable that probiotic strains exert their effects at probiotic strengthening of the intestinal barrier. different stages of carcinogenesis. As evidenced by Commane – Exposure of IEC (and also CEC) to soluble compo- et al. (2005), two different events with their mechanisms nents produced by probiotic microorganisms leads to could be distinguished: the production of specific heat shock proteins (HSPs). These proteins have various functions and are also (1) anti-initiation events: probiotics may alter carcinogen known for their ability to maintain and stabilise metabolism and improve detoxification; they may cytoskeletal integrity. Induction of HSPs may be enhance DNA repair and scavenge electrophiles. derived from proteasome (and therefore NF-κB) inhi- (2) anti promotion events: probiotics may alter gene bition or through signal transduction pathway activa- expression, enhance immunity, suppress inflammation, tion involving mitogen-activated protein kinases promote differentiation, suppress proliferation and (MAPKs) that leads to HSP expression. increase apoptosis. Ann Microbiol (2012) 62:15–30 25 Human Studies epidemiological data. Because of the multitude of dietary assessment methods and food composition tables used in Numerous in vitro studies on human cell lines or animal nutritional epidemiological studies, heterogeneous results studies have investigated the efficacy of probiotic, prebiotic are likely to occur. Standardisation of study methods and synbiotic supplements in reducing the incidence of would facilitate pooled analysis, thereby permitting more colon cancer development. Some studies focus specifically reliable conclusions regarding diet–disease relationships on enzymatic activities of probiotic bacteria against (Friedenreich et al. 1994). carcinogen or genotoxic compounds, or on the immune An interesting overview of human trials on the effect of stimulation of GALT (as discussed in Mechanisms fibre incidence on colon cancer development is reviewed by underlying cancer prevention). Young et al. (2005), where authors deal with the different In vivo human clinical studies, on the contrary, are still types of human epidemiological studies separately (i.e. sparse. Several reviews have attempted to analyse and correlative studies, case control studies, and prospective cluster available case-control studies, or to extrapolate studies). The findings of this work show the importance of results from other epidemiological studies not conducted an intake of at least 35 g fibre/day in order to even consider directly with probiotic and/or prebiotic supplements. The taking the epidemiological study into consideration; more- point at issue here is that it is often not possible to compare over, it is stressed that dietary fibre might be most different in vivo experimental results because of the protective when consumed in natural food sources rather variability in trial designs or the lack of accurate informa- than as a synthetic supplement (Young et al. 2005). tion regarding a particular study. On the other hand, a review by Capurso et al. (2006) Pool-Zobel (2005) and Pool-Zobel and Sauer (2007) gives an overview of available human studies with pro- review experimental and human data about the effect of biotic bacteria. This article has a meaningful title: “Pro- prebiotics, focusing on inulin-type fructans and their biotics and the incidence of colorectal cancer: when incidence on colon cancer risk. They conclude that animal evidence is not evident”. The authors analysed existing studies largely support the assumption that inulin-type data from basic science (animal and in vitro models) and fructans may reduce colorectal cancer (CRC) incidence human (epidemiological and interventional) studies to when supplemented during the initial stages of cancer highlight areas for which more evidence is necessary. They development. Discrepancies can also be found in human interrogated Medline for studies analysing the risk of CRC epidemiological studies carried out to correlate high-fibre and the use of probiotics, as well as screening the diet with the risk of CRC (Liong 2008; Fuchs et al. 1999). references of identified papers. Once again, this review Several such studies deal with the effects of fibre. stresses the paucity of human epidemiological studies Dietary fibres are carbohydrate polymers that are not designed specifically to analyse the effect of probiotics on hydrolysed by the endogenous enzymes of the human CRC incidence; moreover, authors underline the presence intestine. They are composed of a soluble fraction of important confounding factors, such as the role of fibre, (soluble fibre, which also includes prebiotic compounds) dairy products and vitamin D, which are often present. and an insoluble fraction (insoluble fibre, e.g. lignin) that Conflicting epidemiological data regarding the impact of can be present in different ratios. Much evidence fermented dairy product consumption in humans have been supports the view that fibre interacts with the intestinal gathered by authors. Also in this case, human epidemio- microbiota. The magnitude of interaction depends on the logical and interventional studies still do not seem to composition. Some of the effects of fibre, e.g. increased support the promising results observed under experimental faecal bulk and decreased colonic transit, are linked to conditions. These discrepancies may be explained partially fibre itself, while other beneficial effects are linked to by the use of bacterial strains lacking the appropriate fibre fermentation by host microbiota (Queiroz-Monici et characteristics, again stressing the concept that different al. 2005;Roseet al. 2007), leading to a modulation of probiotics might have specific and different clinical microbiota composition. Works reviewed by Liong (2008) applications. In fact, epidemiological studies examine the and the prospective study of Fuchs et al. (1999)stressthat action of “fermented dairy products”, which do contain no significant association was found between fibre intake naturally occurring probiotics but of unknown strains and in and the risk of colorectal adenoma. However, these studies undefined amounts. Therefore, even though a large body of do not evaluate a particular prebiotic compound but rather evidence supports the potential anticarcinogenic action of the incidence of an high-fibre diet, with no detailed probiotics on the basis of the results obtained in both in description of either fibre composition or fibre source. vitro and in vivo models, further evidence is still needed From the epidemiologic point of view, as stressed by (Capurso et al. 2006). Friedenreich et al. (1994), methodological factors can Concluding, a noteworthy human intervention study that influence the results from pooled analysis of nutritional was performed within the EU project SYNCAN (Van Loo 26 Ann Microbiol (2012) 62:15–30 et al. 2005) has yielded some interesting results. This tract. However, their effect is also influenced by strain project involves the integration of an in vitro study to select specificity, host (i.e. genetic factors, indigenous microbiota) the most suitable synbiotic preparation, the application of and by environmental variants (e.g. diet, lifestyle, stress this synbiotic in an in vivo rat model of chemically induced conditions etc.). It is of the utmost importance that the colon cancer, and, as the core of the project, an investiga- peculiar characteristics of a given probiotic strain are tion of synbiotic effects in a human intervention study. The clearly defined in order to target and associate a particular assessment of the survival during gastric transit of the strain to a defined disorder. Moreover, an appropriate administered probiotics (Bifidobacterium animalis subsp. prebiotic compound should be selected and associated to a lactis Bb12 and Lactobacillus rhamnosus GG) was per- specific probiotic microorganism to favour a synergistic formed in three healthy volunteers in a separate study. effect. Unfortunately, despite the huge quantity of data Subsequently, a 12-week randomised, double-blind, available in vitro and on animal models, these outcomes are placebo-controlled trial of a synbiotic food supplement for not often supported by human data. The complexity of reduction in cancer risk bio-markers is carried out. The creating a series of long-term human intervention studies synbiotic used in this study was composed of the two should be overcome and new human studies on probiotics probiotics listed above and the oligofructose-enriched and prebiotics should be financed in order to generate inulin Synergy1 . Polypectomised and colon cancer sub- uncontroversial experimental evidence. Further research is jects having previously undergone ‘curative resection’ for required to identify probiotic, prebiotic or synbiotic colon cancer were selected and assigned randomly to combinations that will be more effective for humans in placebo or synbiotic group. The ability of the synbiotic different conditions. It is very likely that there will be no combination to modulate the gut microbiota was demon- treatment that is ideal for all cases. Probably, the great strated in both the cancer and the polypectomised subjects. efforts of the scientific community to identify the genetic The selectivity of fermentation was shown by the bifido- determinants involved in the health-promoting effects of genic effect, which was accompanied by a decrease of probiotic bacteria (i.e. probiogenomics) (Ventura et al. coliforms in both polypectomised and cancer patient 2009), together with new well-designed human trials, will groups, and a decrease of Clostridium perfringens in the yield significant insights into pre- and pro-biotic mecha- polypectomised group. The authors stress that, since the nisms. However, it is feasible to conclude that pro-, pre- synbiotic supplement modulates the microbiota, it can be and synbiotics hold great potential as a strategy for the hypothesised that the changes in biomarkers monitored in prevention of colorectal cancer. the human anticancer study in test groups vs control group are likely to be the consequence of the administration of an References active synbiotic preparation. The analyses of various markers in this human study show reduced genotoxicity, increased caecal SCFA, particularly butyrate, priming of the Ahotupa M, Saxelin M, Korpela R (1996) Antioxidant properties of Lactobacillus GG. Nutr Today Suppl 31:51–52 immune system to be more efficient to fight cancer cells Alonso L, Cuesta EP, Gilliland SE (2003) Production of free and counteract inflammation, and a reduction in DNA conjugated linoleic acid by Lactobacillus acidophilus and damage (Van Loo et al. 2005). Lactobacillus casei of human intestinal origin. J Dairy Sci 86:1941–1946 Altonsy MO, Andrews SC, Yuohy KM (2010) Differential induction of apoptosis in human colonic carcinoma cells (Caco-2) by Conclusions Atopobium, and commensal, probiotic and enteropathogenic bacteria: mediation by the mitochondrial pathway. Int J Food The use of probiotics, prebiotics and synbiotics to prevent Microbiol 137:190–203 Annuk H, Shchepetova J, Kullisaar T, Songisepp E, Zilmer M, colon cancer has gained much attention in the last decade Mikelsaar M (2003) Characterization of intestinal lactobacilli as due to the fact that in vitro systems and studies in a wide putative probiotic candidates. J Appl Microbiol 94:403–412 range of animal models provide considerable evidence that Ballongue J (2004) Bifidobacteria and probiotic action. In: Salminen S, von Wright A, Ouwehand AC (eds) Lactic acid bacteria. they exert anti-neoplastic effects. This review reports an Microbiological and functional aspects, 3rd edn. Dekker, New overview of the possible mechanisms that could underlie York, p 67 the preventative action of probiotics and prebiotics against Barber DA, Harris SR (1994) Oxygen free radicals and antioxidants: a CRC development. The evolution of CRC is a complicated review. Am Pharm 34:26–35 Barrett E, Ross RP, Fitzgerald GF, Stanton C (2007) Rapid screening multistep process influenced by genetic as well as by method for analyzing the conjugated linoleic acid production environmental factors. Similar considerations can be capabilities of bacterial cultures. Appl Environ Microbiol reported for probiotics and prebiotics. Their preventative 73:2333–2337 effect on CRC development is possibly the sum of a series Belury MA (2002) Inhibition of carcinogenesis by conjugated linoleic of beneficial effects that these supplements exert in the GI acid: potential mechanisms of action. J Nutr 132:2995–2998 Ann Microbiol (2012) 62:15–30 27 Bernstein H, Bernstein C, Payne CM, Dvorakova K, Garewal H Di Giacinto C, Marinaro M, Sanchez M, Strober W, Boirivant M (2005) Bile acids as carcinogens in human gastrointestinal (2005) Probiotics ameliorate recurrent Th1-mediated murine cancers. Mutat Res 589:47–65 colitis by inducing IL-10 and IL-10-dependent TGF-β-bearing Bernstein H, Bernstein C, Payne CM, Dvorak K (2009) Bile acids as regulatory cells. J Immunol 174:3237–3246 endogenous etiologic agents in gastrointestinal cancer. World J Duthie SJ (1999) Folic acid deficiency and cancer: mechanisms of Gastroenterol 15(27):3329–3340 DNA instability. Brit Med Bull 55(3):578–592 Bhattacharya A, Banu J, Rahman M, Causey J, Fernandes G (2006) EFSA (2008) The EFSA Journal 923:1–48 Biological effects of conjugated linoleic acids in health and El-Nezami H, Kankaanpää P, Salminen S, Ahokas J (1998a) disease. J Nutr Biochem 17:789–810 Physicochemical alterations enhance the ability of dairy strains Biavati B, Mattarelli P (2006) The family Bifidobacteriaceae. In: of lactic acid bacteria to remove aflatoxin from contaminated Dworkin M, Falkow S, Rosenberg E, Schleifer K-H, Stackebrandt media. J Food Prot 61:466–468 E (eds) The prokaryotes, 3rd edn, vol 3: a handbook of the biology El-Nezami H, Kankaanpää P, Salminen S, Ahokas J (1998b) Ability of of bacteria: Archea, Bacteria: Firmicutes, Actinomycetes. Springer, dairy strains of lactic acid bacteria to bind a common food New York, pp 322–382 carcinogen, aflatoxin B1. Food Chem Toxicol 36:321–326 Biavati B, Vescovo M, Torriani S, Bottazzi V (2000) Bifidobacteria: El-Nezami HS, Chrevatidis A, Auriola S, Salminen S, Mykkänen H history, ecology, physiology and applications. Ann Microbiol (2002) Removal of common Fusarium toxins in vitro by strains 50:117–131 of Lactobacillus and Propionibacterium. Food Addit Contam Bingham SA, Day NE, Luben R, Ferrari P, Slimani N, Norat T, Clavel- 19:680–686 Chapelon F, Kesse E, Nieters A, Boeing H et al (2003) Dietary Evan GI, Vousden KH (2001) Proliferation, cell cycle and apoptosis in fibre in food and protection against colorectal cancer in the cancer. Nature 411(6835):342–348 European Prospective Investigation into Cancer and nutrition Ewaschuk JB, Walker JW, Diaz H, Madsen KL (2006) Bioproduction (EPIC): an observational study. Lancet 361:1496–1501 of conjugated linoleic acid by probiotic bacteria occurs in vitro Blau S, Rubinstein A, Bass P, Singaram C, Kohen R (1999) Differences and in vivo in mice. J Nutr 136:1483–1487 in the reducing power along the rat GI tract: lower antioxidant FAO/WHO (2002) Joint FAO/WHO (Food and Agriculture Organization/ capacity of the colon. Mol Cell Biochem 194(1–2):185–191 World Health Organization) working group report on drafting Britton RA, Versalovic J (2008) Probiotics and gastrointestinal guidelines for the evaluation of probiotics in food. London, Ontario, infections. Interdiscip Perspect Infect Dis 2008:290769, Epub 4 Canada.guidelines for the evaluation of probiotics in food. Joint Feb 2009 working group report on drafting. London, Ontario 1–11 Brown JM, Attardi LD (2005) The role of apoptosis in cancer Fazeli MR, Hajimohammadali M, Moshkani A, Samadi N, Jamalifar development and treatment response. Nat Rev Cancer 5:231–237 H, Khoshayand MR, Vaghari E, Pouragahi S (2009) Aflatoxin B1 Bruce WR, Giacca A, Medline A (2000) Possible mechanisms relating binding capacity of autochthonous strains of lactic acid bacteria. diet and risk of colon cancer. Cancer Epidemiol Biomarkers Prev J Food Protect 72(1):189–192 9(12):1271–1279 Femia AP, Luceri C, Dolara P, Giannini A, Biggeri A, Salvadori M, Bueno DJ, Casale CH, Pizzolitto RP, Salvano MA, Oliver G (2007) Clune Y, Collins KJ, Paglierani M, Caderni G (2002) Anti- Physical adsorption of aflatoxin B1 by Lactic Acid Bacteria and tumorigenic activity of the prebiotic inulin enriched with Saccharomyces cerevisiae: a theoretical model. J Food Protect 70 oligofructose in combination with the probiotics Lactobacillus (9):2148–2154 rhamnosus and Bifidobacterium lactis on azoxymethane-induced Capurso G, Marignani M, Delle Fave G (2006) Probiotics and the colon carcinogenesis in rats. Carcinogenesis 23(11):1953–1960 incidence of colorectal cancer: when evidence is not evident. Friedenreich CM, Brant RF, Riboli E (1994) Influence of methodo- Digest Liver Dis 38(S2):S277–S282 logic factors in a pooled analysis of 13 case-control studies of Cebra JJ (1999) Influences of microbiota on intestinal immune system colorectal cancer and dietary fiber. Epidemiology 5(1):66–79 development. Am J Clin Nutr 69(S):1046S–1051S Fuchs CS, Giovannucci EL, Colditz GA, Hunter DJ, Stampfer MJ, Choi SS, Kim Y, Han KS, You S, Oh S, Kim SH (2006) Effects of Rosner B, Speizer FE, Willet WC (1999) Dietary fiber and the Lactobacillus strains on cancer cell proliferation and oxidative risk of colorectal cancer and adenoma in women. New Engl J stress in vitro. Lett Appl Microbiol 42:452–458 Med 340(3):169–176 Coakley M, Ross RP, Nordgren M, Fitzgerald G, Devery R, Stanton C Fuchs S, Sontag G, Stidl R, Ehrlich V, Kundi M, Knasmüller S (2008) (2003) Conjugated linoleic acid biosynthesis by human-derived Detoxification of patulin and ochratoxin A, two abundant Bifidobacterium species. J Appl Microbiol 94:138–145 mycotoxins, by lactic acid bacteria. Food Chem Toxicol Coakley M, Johnson MC, McGrath E, Rahman S, Ross RP, Fitzgerald 46:1398–1407 GF, Devery R, Stanton C (2006) Intestinal bifidobacteria that Fuller R (1989) Probiotics in man and animals: a review. J Appl produce trans-9, trans-11 CLA: a fatty acid with anti- Bacteriol 66:365–378 proliferative activity against human colon SW480 and HT-29 Fuller R (1991) Probiotics in human medicine. Gut 32:439–442 cancer cells. Nutr Cancer 56:95–102 Gaggìa F, Mattarelli P, Biavati B (2010) Probiotics and prebiotics in Coakley M, Banni S, Johnson MC, Mills S, Devery R, Fitzgerald G, animal feeding for safe food products. Int J Food Microbiol 141: Paul Ross R, Stanton C (2009) Inhibitory effect of conjugated S15–S28 alpha-linolenic acid from bifidobacteria of intestinal origin on García P, Rodríguez L, Rodríguez A, Martínez B (2010) Food SW480 cancer cells. Lipids 44(3):249–256 biopreservation: promising strategies using bacteriocins, bacter- Commane D, Hughes R, Shortt C, Rowland I (2005) The potential iophages and endolysins. Trends Food Sci Technol 21:373–382 mechanisms involved in the anti-carcinogenic action of pro- Gibson GR, Roberfroid MB (1995) Dietary modulation of the human biotics. Mutat Res 591:276–289 colonic microbiota: introducing the concept of prebiotics. J Nutr De Visser KE, Eichten A, Coussens LM (2006) Paradoxical roles of 125:1401–1412 the immune system during cancer development. Nat Rev Cancer Guarner F, Malagelada JR (2003) Gut flora in health and disease. 6:24–37 Lancet 361:512–519 De Vuyst L, Leroy F (2007) Bacteriocins from Lactic Acid Bacteria: Guillén H, Curiel JA, Landete JM, Muñoz R, Herraiz T (2009) production, purification, and food applications. J Mol Microbiol Characterization of a nitroreductase with selective nitroreduction Biotechnol 13:194–199 properties in the food and intestinal lactic acid bacterium 28 Ann Microbiol (2012) 62:15–30 Lactobacillus plantarum WCFS1. J Agric Food Chem 57 Lamprecht SA, Lipkin M (2003) Chemoprevention of colon cancer by (21):10457–10465 calcium, vitamin D and folate: molecular mechanisms. Nat Rev Halliwell B (1996) Mechanisms involved in the generation of free Cancer 3:601–614 radicals. Pathos Biol 44:6–13 Lan A, Bruneau A, Bensaada M, Philippe C, Bellaud P, Rabot S, Jan Halliwell B (2007) Oxidative stress and cancer: Have we moved G (2008) Increased induction of apoptosis by Propionibacterium forward? Biochem J 401:1–11 freudenreichii TL133 in colonic mucosal crypts of human Hao WL, Lee YK (2004) Microflora of the gastrointestinal tract: a microbiota-associated rats treated with 1,2-dimethylhydrazine. review. Methods Mol Biol 491–502. Br J Nutr 100:1251–1259 Haskard C, Binnion C, Ahokas J (2000) Factors affecting the Le Leu RK, Brown IL, Hu Y, Bird AR, Jackson M, Esterman A, sequestration of aflatoxin by Lactobacillus rhamnosus strain Young GP (2005) A synbiotic combination of resistant starch and GG. Chem Biol Interact 128:39–49 Bifidobacterium lactis facilitates apoptotic deletion of Haskard CA, El-nezami HS, Kankaanpää PE, Salminen S, Ahokas JT carcinogen-damaged cells in rat colon. J Nutr 135:996–1001 (2001) Surface binding of aflatoxin B1 by lactic acid bacteria. Le Leu RK, Hu Y, Brown IL, Woodman RJ, Young GP (2010) Appl Environ Microb 67(7):3086–3091 Synbiotic intervention of Bifidobacterium lactis and resistant Hattori M, Taylor TD (2009) The human intestinal microbiome: a new starch protects against colorectal cancer development in rats. frontier of human biology. DNA Res 16:1–12 Carcinogenesis 31(2):246–251 He B, Xu W, Santini PA, Polydorides AD, Chiu A, Estrella J, Shan M, LeBlanc JG, Matar C, Valdéz JC, LeBlanc J, Perdigon G (2002) Chadburn A, Villanacci V, Plebani A, Knowles DM, Rescigno M, Immunomodulating effects of peptidic fractions issued from milk Cerutti A (2007) Intestinal bacteria trigger t cell-independent fermented with Lactobacillus helveticus. J Dairy Sci 85:2733–2742 immunoglobulin A class switching by inducing epithelial-cell Lee W-J (2009) Bacterial-modulated host immunity and stem cell secretion of the cytokine APRIL. Immunity 26:812–826 activation for gut homeostasis. Genes Dev 23(19):2260–2265 Hernandez-Mendoza A, Guzman-de-Peña D, Garcia HS (2009) Key Lee DK, Jang S, Kim MJ, Kim JH, Chung MJ, Kim KJ, Ha NJ (2008) role of teichoic acids on aflatoxin B1 binding by probiotic Anti-proliferative effects of Bifidobacterium adolescentis bacteria. J Appl Microbiol 107:395–403 SPM0212 extract on human colon cancer cell lines. BMC Cancer Hord NG (2008) Eukaryotic-microbiota crosstalk: potential mecha- 8:310 nisms for health benefits of prebiotics and probiotics. Annu Rev Ley RE, Peterson DA, Gordon JI (2006) Ecological and evolutionary Nutr 28:215–231 forces shaping microbial diversity in the human intestine. Cell Humblot C, Murkovic M, Rigottier-Gois L, Bensaada M, Bouclet A, 124:837–848 Andrieux C, Anba J, Rabot S (2007) β-Glucuronidase in human Lin MY, Chang FJ (2000) Antioxidative effect of intestinal bacteria intestinal microbiota is necessary for the colonic genotoxicity of Bifidobacterium longum ATCC 15708 and Lactobacillus acid- the food-borne carcinogen 2-amino-3-methylimidazo[4,5-f]quin- ophilus ATCC 4356. Dig Dis Sci 45:1617–1622 oline in rats. Carcinogenesis 28(11):2419–2425 Lin TY, Lin CW, Lee CH (1999) Conjugated linoleic acid concentra- International Agency for Research on Cancer (1993) Some naturally tion as affected by lactic cultures and added linoleic acid. Food occurring substances: food items and constituents heterocyclic Chem 67:1–5 aromatic amines and mycotoxins. IARC, Lyon Liong M-T (2008) Roles of probiotics and prebiotics in colon cancer Iyer R, Tomar SK (2009) Folate: a functional food constituent. J Food prevention: postulated mechanisms and in vivo evidence. Int J Sci 74(9):R114–R122 Mol Sci 9:854–863 Jain S, Yadav M, Menon S, Yadav H, Marotta F (2009) Anticarcino- Macfarlane GT, Cummings JH (1999) Probiotics and prebiotics: can genic effects of probiotics, prebiotics, and synbiotics. In: regulating the activities of intestinal bacteria benefit health. BMJ Finocchiaro ET, Cho SS (eds) Handbook of prebiotics and 318:999–1003 probiotics: ingredients, health benefits and food applications, 1st Macpherson AJ, Harris NL (2002) Interactions between commensal edn. CRC, Boca Raton, pp 273–287 intestinal bacteria and the immune system. Nat Rev Immunol Jiang H-R, Lu Z-G, Ma Y-Y, Liu N (2009) Target colonization of 4:478–485 Bifidobacterium bifidum in tumor-bearing mouse model and its Macpherson AJ, Slack E (2007) The functional interactions of immune activation on macrophages. Tumor 29(8):721–726 commensal bacteria with intestinal secretory IgA. Curr Opin Kabak B, Dobson ADW (2009) Biological strategies to counteract the Gastroen 23(6):673–678 effects of mycotoxins. J Food Protect 72(9):2006–2016 Madsen K, Cornish A, Soper P, McKaigney C, Jijon H, Yachimec C, Kelley NS, Hubbard NE, Erickson KL (2007) Conjugated linoleic Doyle J, Jewell L, De Simone C (2001) Probiotic bacteria acid isomers and cancer. J Nutr 137:2599–2607 enhance murine and human intestinal epithelial barrier function. Kishino S, Ogawa J, Omura Y, Matsumura K, Shimizu S (2002) Gastroenterology 121:580–591 Conjugated linoleic acid production from linoleic acid by lactic Maldonado Galdeano C, de Moreno de LeBlanc A, Vinderola G, acid bacteria. J Am Oil Chem Soc 79:159–163 Bibas Bonet ME, Perdigon G (2007) Proposed model: mecha- Kruszewska D, Lan J, Lorca G, Yanagisawa N, Marklinder I, Ljungh nisms of immunomodulation induced by probiotic bacteria. Clin Å (2002) Selection of lactic acid bacteria as probiotic strains by Vaccine Immunol 14(5):485–492 in vitro tests. Microb Ecol Health Dis 29:37–49 Marchesi JR (2010) Prokaryotic and eukaryotic diversity of the human Kullisaar T, Zilmer M, Mikelsaar M, Vihalemm T, Annuk H, Kairane gut. Adv Appl Microbiol 72:43–62 C, Kilk A (2002) Two antioxidative lactobacilli strains as Marco ML, Pavan S, Kleerebezem M (2006) Towards understanding promising probiotics. Int J Food Microbiol 72:215–224 molecular modes ofprobiotic action. Curr Opin Biotechnol Kumar M, Kumar A, Nagpal R, Mohania D, Behare P, Verma V, 17:204–210 Kumar P, Poddar D, Aggarwal PK, Henry CJK, Jain S, Yadav H Marotta F, Naito Y, Minelli E, Tajiri H, Bertuccelli J, Wu CC, Min CH, (2010) Cancer-preventing attributes of probiotics: an update. Int J Hotten P, Fesce E (2003) Chemopreventive effect of a probiotic Food Sci Nutr 61(5):473–496 preparation on the development of preneoplastic and neoplastic Lahtinen SJ, Haskard CA, Ouwehand AC, Salminen SJ, Ahokas JT colonic lesions: an experimental study. Hepatogastroenterology (2004) Binding of aflatoxin B1 to cell wall components of 50(54):1914–1918 Lactobacillus rhamnosus strain GG. Food Addit Contam 21:158– Marotti I, Bonetti A, Biavati B, Catizone P, Dinelli G (2007) 164 Biotransformation of common bean (Phaseolus vulgaris L) Ann Microbiol (2012) 62:15–30 29 flavonoid glycosides by Bifidobacterium species from human Linneberg A, Nielsen HB, Pelletier E, Renault P, Sicheritz-Ponten intestinal origin. J Agric Food Chem 55:3913–3919 T, Turner K, Zhu H, Yu C, Li S, Jian M, Zhou Y, Li Y, Zhang X, Matsumoto S, Hara T, Nagaoka M, Mike A, Mitsuyama K, Sako T, Li S, Qin N, Yang H, Wang J, Brunak S, Doré J, Guarner F, Yamamoto M, Kado S, Takada T (2009) A component of Kristiansen K, Pedersen O, Parkhill J, Weissenbach J, MetaHIT polysaccharide peptidoglycan complex on Lactobacillus induced Consortium, Bork P, Ehrlich SD, Wang J (2010) A human gut an improvement of murine model of inflammatory bowel disease microbial gene catalogue established by metagenomic sequenc- and colitis-associated cancer. Immunology 128:e170–e180 ing. Nature 464(7285):59–65 McBain AJ, Macfarlane GT (1998) Ecological and physiological Queiroz-Monici KS, Costa GEA, da Silva N, Reis SMPM, de Oliveira studies on large intestinal bacteria in relation to production of AC (2005) Bifidogenic effect of dietary fiber and resistant starch hydrolytic and reductive enzymes involved in formation of from leguminous on the intestinal microbiota of rats. Nutrition genotoxic metabolites. J Med Microbiol 47(5):407–416 21:602–608 McCracken VJ, Lorenz RG (2001) The gastrointestinal ecosystem: a Rafii F, Franklin W, Cerniglia CE (1990) Azoreductase activity of precarious alliance among epithelium, immunity and microbiota. anaerobic bacteria isolated from human intestinal microflora. Cell Microbiol 3(1):1–11 Appl Environ Microbiol 56(7):2146–2151 Mills S, Stanton C, Ross RP (2009) Microbial production of Rafter J, Bennett M, Caderni G, Clune Y, Hughes R, Karlsson PC, bioactives: from fermented functional foods to probiotic mech- Klinder A, O’Riordan M, O’Sullivan GC, Pool-Zobel B, anisms. Aust J Dairy Technol 64(1):41–49 Rechkemmer G, Roller M, Rowland I, Salvadori M, Thijs H, Mowat AM (2003) Anatomical basis of tolerance and immunity to Van Loo J, Watzl B, Collins JK (2007) Dietary synbiotics reduce intestinal antigens. Nat Rev Immunol 3:331–341 cancer risk factors in polypectomized and colon cancer patients. Nagao K, Yanagita T (2005) Conjugated fatty acids in food and their Am J Clin Nutr 85(2):488–496 health benefits. J Biosci Bioeng 100:152–157 Rastall RA, Gibson GR, Gill HS, Guarner F, Klaenhammer TR, Pot B, Neutra MR, Pringault E, Kraehenbuhl J-P (1996) Antigen sampling Reid G, Rowland IR, Sanders ME (2005) Modulation of the across epithelial barriers and induction of mucosal immune microbial ecology of the human colon by probiotics, prebiotics responses. Annu Rev Immunol 14:275–300 and synbiotics to enhance human health: an overview of enabling O’Flaherty S, Saulnier DM, Pot B, Versalovic J (2010) How can science and potential applications. FEMS Microbiol Ecol 52:145–152 probiotics and prebiotics impact mucosal immunity? Gut Microbes 1(5):293–300 Reddy BS, Hanson D, Mangat S, Mathews L, Sbaschnig M, Sharma O’Hara AM, Shanahan F (2006) The gut flora as a forgotten organ. C, Simi B (1980) Effect of high-fat, high-beef diet and of mode EMBO Rep 7:688–693 of cooking of beef in the diet on fecal bacterial enzymes and Oatley JT, Rarick MD, Ji GE, Linz JE (2000) Binding of aflatoxin B1 fecal bile acids and neutral sterols. J Nutr 110:1880–1887 to bifidobacteria in vitro. J Food Protect 63:1133–1136 Roberfroid MB (1998) Prebiotics and synbiotics: concepts and Özdemir Ö (2010) Various effects of different probiotic strains in nutritional properties. Br J Nutr 80:S197–S202 allergic disorders: An update from laboratory and clinical data. Roberfroid M (2007) Prebiotics: the concept revisited. J Nutr Clin Exp Immunol 160(3):295–304 137:830S–837S Park J-H, Um J-I, Lee B-J, Goh J-S, Park S-Y, Kim W-S, Kima P-H Rodríguez-Alcalá LM, Braga T, Gomes A, Malcata FX, Fontecha J (2002) Encapsulated Bifidobacterium bifidum potentiates intesti- (2011) Quantitative and qualitative determination of CLA nal IgA production. Cell Immunol 219:22–27 produced by Bifidobacterium and lactic acid bacteria by Parke DV, Ioannides C (1990) Role of cytochrome P-450 in mouse combining spectrophotometric and Ag -HPLC techniques. Food liver tumor production. Prog Clin Biol Res 331:215–230 Chem 125:1373–1378. doi:10.1016/j.foodchem.2010.10.008 Perdigon G, Vintiñi E, Alvarez S, Medina M, Medici M (1999) Study of Rook GA, Brunet LR (2005) Microbes, immunoregulation, and the the possible mechanisms involved in the mucosal immune system gut. Gut 54:317–320 activation by lactic acid bacteria. J Dairy Sci 82(6):1108–1114 Rose DJ, DeMeo MT, Keshavarzian A, Hamaker BR (2007) Influence Perdigón G, Maldonado Galdeano C, Valdez JC, Medici M (2002) of dietary fiber on inflammatory bowel disease and colon cancer: Interaction of lactic acid bacteria with the gut immune system. importance of fermentation pattern. Nutr Rev 65(2):51–62 Eur J Clin Nutr 56(S4):S21–S26 Rumbo M, Anderle P, Didierlaurent A, Sierra F, Debard N, Sirard JC, Pessi T, Sütas Y, Hurme M, Isolauri E (2000) Interleukin-10 generation Finke D, Kraenhenbuhl JP (2004) How the gut link innate and in atopic children following oral Lactobacillus rhamnosus GG. adaptative immunity. Ann N Y Acad Sci 1029:16–21 Clin Exp Allergy 30:1804–1808 Saikali J, Picard C, Freitas M, Holt P (2004) Fermented milks, Pierides M, El-Nezami H, Peltonen K, Salminen S, Ahokas J (2000) probiotic cultures, and colon cancer. Nutr Cancer 49:14–24 Ability of dairy strains of lactic acid bacteria to bind aflatoxin Sartor RB (2004) Therapeutic manipulation of the enteric microflora M1 in a food model. J Food Protect 63:645–650 in inflammatory bowel diseases: antibiotics, probiotics, and Piskula MK (2000) Factors affecting flavonoids absorption. Biofactors prebiotics. Gastroenterology 126(6):1620–1633 12:175–180 Scantlebuy-Manning T, Gibson GR (2004) Prebiotics. Best Pract Res Pompei A, Cordisco L, Amaretti A, Zanoni S, Matteuzzi D, Rossi M Cl Ga 18:287–298 (2007) Folate production by bifidobacteria as a potential pro- Schiffrin EJ, Blum S (2002) Interactions between the microbiota and biotic property. Appl Environ Microbiol 73(1):179–185 the intestinal mucosa. Eur J Clin Nutr 56(3):S60–S64 Pool-Zobel BL (2005) Inulin-type fructans and reduction in colon Servin AL (2004) Antagonistic activities of lactobacilli and cancer risk: review of experimental and human data. Br J Nutr 93 bifidobacteria against microbial pathogens. FEMS Microbiol (S1):S73–S90 Rev 28:405–440 Pool-Zobel BL, Sauer J (2007) Overview of experimental data on Shanahan F (2002) The host–microbe interface within the gut. Best reduction of colorectal cancer risk by inulin-type fructans. J Nutr Pract Res Clin Gastroenterol 16:915–931 137:2580S–2584S Suzuki K, Benno Y, Mitsuoka T, Takebe S, Kobashi K, Hase J (1979) Qin J, Li R, Raes J, Arumugam M, Burgdorf KS, Manichanh C, Urease-producing species of intestinal anaerobes and their Nielsen T, Pons N, Levenez F, Yamada T, Mende DR, Li J, Xu J, activities. Appl Environ Microbiol 37(3):379–382 Li S, Li D, Cao J, Wang B, Liang H, Zheng H, Xie Y, Tap J, Takagi A, Matsuzaki T, Sato M, Nomoto K, Morotomi M, Yokokura T Lepage P, Bertalan M, Batto JM, Hansen T, Le Paslier D, (2001) Enhancement of natural killer cytotoxicity delayed murine 30 Ann Microbiol (2012) 62:15–30 carcinogenesis by a probiotic microorganism. Carcinogenesis Van Nieuwenhove CP, Oliszewski R, González SN, Pérez Chaia AB 22:599–605 (2007) Conjugated linoleic acid conversion by dairy bacteria cultured Takagi A, Ikemura H, Matsuzaki T, Sato M, Nomoto K, Morotomi M, in MRS broth and buffalo milk. Lett Appl Microbiol 44(5):467–474 Yokokura T (2008) Relationship between the in-vitro response of Ventura M, O'Flaherty S, Claesson MJ, Turroni F, Klaenhammer TR, dendritic cells to Lactobacillus and prevention of tumorigenesis van Sinderen D, O'Toole PW (2009) Genome-scale analyses of in the mouse. J Gastroenterol 43:661–669 health-promoting bacteria: probiogenomics. Nat Rev Microbiol 7 Thirabunyanon M (2011) Biotherapy for and protection against (1):61–71 gastrointestinal pathogenic infections via action of probiotic Villena J, Medina M, Vintiñi E, Alvarez S (2008) Stimulation of bacteria. Maejo Int J Sci Technol 5(01):108–128 respiratory immunity by oral administration of Lactococcus Trush MA, Kensler TW (1991) An overview of the relationship lactis. Can J Microbiol 54(8):630–638 between oxidative stress and chemical carcinogenesis. Free Radic Vuillaume M (1987) Reduced oxygen species, mutation, induction and Biol Med 10:201–209 cancer initiation. Mutat Res 186:43–72 Valko M, Leibfritz D, Moncol J, Cronin MTD, Mazur M, Telser J Young GP, Hu Y, Le Leu RK, Nyskohus L (2005) Dietary fibre and (2007) Free radicals and antioxidants in normal physiological colorectal cancer: a model for environment-gene interactions. functions and human disease. Int J Biochem Cell B 39(1):44–84 Mol Nutr Food Res 49:571–584 Van Loo J, Clune Y, Bennet M, Collins JK (2005) The SYNCAN Yu DCW, Waby JS, Chirakkal H, Staton CA, Corfe BM (2010) project: goals, set-up, first results and settings of the human Butyrate suppresses expression of neuropilin I in colorectal cell intervention study. Br J Nutr 93(S1):S91–S98 lines through inhibition of Sp1 transactivation. Mol Cancer 9:276

Journal

Annals of Microbiology – Springer Journals

Published: Jul 20, 2011

Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Role of intestinal microbiota in colon cancer prevention

Role of intestinal microbiota in colon cancer prevention

Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Role of intestinal microbiota in colon cancer prevention

Role of intestinal microbiota in colon cancer prevention

References (29)

Abstract

Journal

Recommended Articles

There are no references for this article.

Our policy towards the use of cookies