Bifidobacterium Lactis sp. 420 up-regulates cyclooxygenase (Cox)-1 and down-regulates Cox-2 gene expression in a Caco-2 cell culture model

Exploring the Diet-Gut Microbiota-Epigenetics Crosstalk Relevant to Neonatal Diabetes

Neonatal diabetes (NDM) is a rare monogenic disorder that presents as hyperglycemia during the first six months of life. The link between early-life gut microbiota dysbiosis and susceptibility to NDM remains uncertain. Experimental studies have demonstrated that gestational diabetes mellitus (GDM) could develop into meconium/gut microbiota dysbiosis in newborns, and thus, it is thought to be a mediator in the pathogenesis of NDM. Epigenetic modifications have been considered as potential mechanisms by which the gut microbiota and susceptibility genes interact with the neonatal immune system. Several epigenome-wide association studies have revealed that GDM is associated with neonatal cord blood and/or placental DNA methylation alterations. However, the mechanisms linking diet in GDM with gut microbiota alterations, which may in turn induce the expression of genes linked to NDM, are yet to be unraveled. Therefore, the focus of this review is to highlight the impacts of diet, gut microbiota, and epigenetic crosstalk on altered gene expression in NDM.

An Updated Review on Prebiotics: Insights on Potentials of Food Seeds Waste as Source of Potential Prebiotics

Prebiotics are a group of biological nutrients that are capable of being degraded by microflora in the gastrointestinal tract (GIT), primarily Lactobacilli and Bifidobacteria. When prebiotics are ingested, either as a food additive or as a supplement, the colonic microflora degrade them, producing short-chain fatty acids (SCFA), which are simultaneously released in the colon and absorbed into the blood circulatory system. The two major groups of prebiotics that have been extensively studied in relation to human health are fructo-oligosaccharides (FOS) and galactooligosaccharides (GOS). The candidature of a compound to be regarded as a prebiotic is a function of how much of dietary fiber it contains. The seeds of fruits such as date palms have been reported to contain dietary fiber. An increasing awareness of the consumption of fruits and seeds as part of the daily diet, as well as poor storage systems for seeds, have generated an enormous amount of seed waste, which is traditionally discarded in landfills or incinerated. This cultural practice is hazardous to the environment because seed waste is rich in organic compounds that can produce hazardous gases. Therefore, this review discusses the potential use of seed wastes in prebiotic production, consequently reducing the environmental hazards posed by these wastes.

The Microbiota and the Relationship with Colorectal Cancer: Surgical Complications—A Review

Colorectal cancer (CRC) is one of the most common cancers and represents a major global health burden. While genetics are implicated in a portion of CRC patients, most cases are sporadic. A new possibility of tumor initiation and promotion might be microbiome composition. It was recently shown that bacteria from the gut microbiome might be used as biomarkers for CRC detection, especially Fusobacterium nucleatum, Peptostreoptococcus stomatis, Parvimonas mica, Solobacterium moorei, and Peptostreptococcus anaerobius. Conversely, the healthy gut microbiome is mostly colonized by Bacterioides (Bacterioides fragilis, vulgatus, uniformis), Firmicutes (Clostridium spp., Ruminococcus faecis, Enterococcus faecium), and Actinobacteria (Bifidobacterium bifidum). Some strains of gut bacteria favor tumor promotion through DNA and RNA damage (directly or through interaction with other known food carcinogens) and through local immune inhibition. It is possible that bacteria (e.g., Bacillus polyfermenticus, Alistipes shahii, Lactobacillus casei) exist with protective functions against tumor promotion. Despite current advances in colorectal cancer treatment, especially in the medical oncology and radiotherapy domains, surgery remains the mainstay of curative treatment for colorectal cancer patients, even in the oligometastatic setting. Surgical complications like anastomotic leakage, excessive blood loss, abscess, and abdominal sepsis can reduce 1-year and 5-year overall survival and increase the recurrence rates for these patients; therefore, we reviewed currently published data focusing on the relationship between gut microbiota and postoperative complications for colorectal cancer patients.

Molecular interactions between the intestinal microbiota and the host

The intestine is the most densely colonized region of the body, inhabited by a diverse community of microbes. The functional significance of the intestinal microbiota is not yet fully understood, but it is known that the microbiota is implicated in numerous physiological processes of the host, such as metabolism, nutrition, the immune system, and regulation of behavior and mood. This article reviews recent findings on how bacteria of the intestinal microbiota interact with the host.

Microbiota‐microbiota and microbiota‐host interactions are mediated by direct cell contact and by metabolites either produced by bacteria or produced by the host or the environment and metabolized by bacteria. Among them are short‐chain fatty, including butyrate, propionate, and acetate. Other examples include polyamines, linoleic acid metabolites, tryptophan metabolites, trimethylamine‐N‐oxide, vitamins, and secondary bile acids. These metabolites are involved in regulating the cell cycle, neurobiological signaling, cholesterol and bile acid metabolism, immune responses, and responses to antioxidants. Understanding the host‐microbiota pathways and their modulation will allow the identification of individualized therapeutic targets for many diseases. This overview helps to facilitate and promote further research in this field.

Microbiome and Cardiovascular Disease

Atherosclerotic cardiovascular disease (ASCVD) is a prime example of a systems disease. In the initial phase, apolipoprotein B-containing cholesterol-rich lipoproteins deposit excess cholesterol in macrophage-like cells that subsequently develop into foam cells. A multitude of systemic as well as environmental factors are involved in further progression of atherosclerotic plaque formation. In recent years, both oral and gut microbiota have been proposed to play an important role in the process at different stages. Particularly bacteria from the oral cavity may easily reach the circulation and cause low-grade inflammation, a recognized risk factor for ASCVD. Gut-derived microbiota on the other hand can influence host metabolism on various levels. Next to translocation across the intestinal wall, these prokaryotes produce a great number of specific metabolites such as trimethylamine and short-chain fatty acids but can also metabolize endogenously formed bile acids and convert these into metabolites that may influence signal transduction pathways. In this overview, we critically discuss the novel developments in this rapidly emerging research field.

The Human Gut Microbiota: A Key Mediator of Osteoporosis and Osteogenesis

An expanding body of research asserts that the gut microbiota has a role in bone metabolism and the pathogenesis of osteoporosis. This review considers the human gut microbiota composition and its role in osteoclastogenesis and the bone healing process, specifically in the case of osteoporosis. Although the natural physiologic processes of bone healing and the pathogenesis of osteoporosis and bone disease are now relatively well known, recent literature suggests that a healthy microbiome is tied to bone homeostasis. Nevertheless, the mechanism underlying this connection is still somewhat enigmatic. Based on the literature, a relationship between the microbiome, osteoblasts, osteoclasts, and receptor activator of nuclear factor-kappa-Β ligand (RANKL) is contemplated and explored in this review. Studies have proposed various mechanisms of gut microbiome interaction with osteoclastogenesis and bone health, including micro-RNA, insulin-like growth factor 1, and immune system mediation. However, alterations to the gut microbiome secondary to pharmaceutical and surgical interventions cannot be discounted and are discussed in the context of clinical therapeutic consideration. The literature on probiotics and their mechanisms of action is examined in the context of bone healing. The known and hypothesized interactions of common osteoporosis drugs and the human gut microbiome are examined. Since dysbiosis in the gut microbiota can function as a biomarker of bone metabolic activity, it may also be a pharmacological and nutraceutical (i.e., pre- and probiotics) therapeutic target to promote bone homeostasis.

Probiotic-Induced Tolerogenic Dendritic Cells: A Novel Therapy for Inflammatory Bowel Disease?

Inflammatory bowel diseases (IBDs) are immune-mediated, chronic relapsing diseases with a rising prevalence worldwide in both adult and pediatric populations. Treatment options for immune-mediated diseases, including IBDs, are traditional steroids, immunomodulators, and biologics, none of which are capable of inducing long-lasting remission in all patients. Dendritic cells (DCs) play a fundamental role in inducing tolerance and regulating T cells and their tolerogenic functions. Hence, modulation of intestinal mucosal immunity by DCs could provide a novel, additional tool for the treatment of IBD. Recent evidence indicates that probiotic bacteria might impact immunomodulation both in vitro and in vivo by regulating DCs’ maturation and producing tolerogenic DCs (tolDCs) which, in turn, might dampen inflammation. In this review, we will discuss this evidence and the mechanisms of action of probiotics and their metabolites in inducing tolDCs in IBDs and some conditions associated with them.

Screening of New Potential Probiotics Strains against Photobacterium damselae Subsp. piscicida for Marine Aquaculture

On intensive fish farms, 10% of the population dies exclusively from pathogens, and Photobacterium damselae subsp. Piscicida (Ph. damselae subsp. Piscicida), the bacteria causing pasteurellosis in marine aquaculture, is one of the major pathogens involved. The objective of this study was to obtain new probiotic strains against pasteurellosis in order to limit the use of chemotherapy, avoiding the environmental repercussions generated by the abusive use of these products. In this study, 122 strains were isolated from the gills and intestines of different marine fish species and were later evaluated in vitro to demonstrate the production of antagonistic effects, the production of antibacterial substances, adhesion and growth to mucus, resistance to bile and resistance to pH gradients, as well as its harmlessness and the dynamic of expression of immune-related genes by real-time PCR after administration of the potential probiotic in the fish diet. Only 1/122 strains showed excellent results to be considered as a potential probiotic strain and continue its characterization against Ph. damselae subsp. piscicida to determine its protective effect and elucidating in future studies its use as a possible probiotic strain for marine aquaculture.

Duration of Prebiotic Intake Is a Key-Factor for Diet-Induced Modulation of Immunity and Fecal Fermentation Products in Dogs

Prebiotics promote health benefits, however, there is no consensus on the minimal intake period required in order to obtain good results. This study evaluated the effect of the time of ingestion of prebiotics on fecal fermentation products and immunological features in dogs. Twenty-four adult dogs were randomly distributed in a block design with six groups and four treatments. Diet and intake period were variation factors. Diets were either a control diet without the addition of prebiotic (CO) or with the inclusion of 1% of a commercial product containing a minimum of 0.38% galactooligosaccharides (GOS), 0.5% (B1) or 1% (B2) of a prebiotic blend. Time variable was set at 30 and 60 days for evaluation of immunity and gut health. Results were analyzed in the Statistical Analysis System software (SAS), version 9.4, considering the repeated measures over time design, and means were compared by the Tukey test and p < 0.05 was significant. Propionic acid was the only variable that had an interaction effect, with reduction of this metabolite in treatment B2 in the period of 60 days. At T60, concentrations of immunoglobulin A, lactic acid, and pH in the feces increased (p < 0.05) in all treatments regardless of prebiotic inclusion or not. GOS increased fecal score and lactic acid concentrations. Therefore, a 60-day intake period of a prebiotic blend was not sufficient to modulate fecal and immune variables and higher concentrations of a single prebiotic would be more relevant for results.

Bifidobacteriumlongum subsp. infantis CECT7210 (B. infantis IM-1®) Displays In Vitro Activity against Some Intestinal Pathogens

Certain non-digestible oligosaccharides (NDO) are specifically fermented by bifidobacteria along the human gastrointestinal tract, selectively favoring their growth and the production of health-promoting metabolites. In the present study, the ability of the probiotic strain Bifidobacterium longum subsp. infantis CECT7210 (herein referred to as B. infantis IM-1^®) to utilize a large range of oligosaccharides, or a mixture of oligosaccharides, was investigated. The strain was able to utilize all prebiotics screened. However, galactooligosaccharides (GOS), and GOS-containing mixtures, effectively increased its growth to a higher extent than the other prebiotics. The best synbiotic combination was used to examine the antimicrobial activity against Escherichia coli, Cronobacter sakazakii, Listeria monocytogenes and Clostridium difficile in co-culture experiments. C. difficile was inhibited by the synbiotic, but it failed to inhibit E. coli. Moreover, Cr. sakazakii growth decreased during co-culture with B. infantis IM-1^®. Furthermore, adhesion experiments using the intestinal cell line HT29 showed that the strain IM-1^® was able to displace some pathogens from the enterocyte layer, especially Cr. sakazakii and Salmonella enterica, and prevented the adhesion of Cr. sakazakii and Shigella sonnei. In conclusion, a new synbiotic (probiotic strain B. infantis IM-1^® and GOS) appears to be a potential effective supplement for maintaining infant health. However, further studies are needed to go more deeply into the mechanisms that allow B.infantis IM-1^® to compete with enteropathogens.

Anti-cancer properties of Escherichia coli Nissle 1917 against HT-29 colon cancer cells through regulation of Bax/Bcl-xL and AKT/PTEN signaling pathways

Objectives

Chemotherapies used to treat colon cancer might often fail due to the emergence of chemoresistance and side effects. Escherichia coli Nissle 1917 (EcN) is a beneficial probiotic, whose molecular mechanisms in the prevention of colon cancer are yet to be fully understood. The present study assessed the anti-cancer effects of EcN treatments in human colorectal cancer, HT-29 cell line, with the analysis of related mechanisms.

Materials and Methods

The co-culture conditioned-media (CM) of EcN with adenocarcinoma HT-29 cells and heat-inactivated bacteria (HIB) were applied for the treatment of the HT-29 cells. To study the inhibition potential of CM and HIB on cancer cells, various cellular/molecular analyses were implemented, including DAPI-staining and DNA ladder assays, flow cytometry and Real-time quantitative PCR (qPCR), as well as Western blotting analyses.

Results

Our results indicated that EcN could elicit apoptotic impacts on the colon cancer HT-29 cells by up-regulating PTEN and Bax and down-regulating AKT1 and Bcl-xL genes.

Conclusion

Based on our findings, EcN is proposed as a useful supplemental probiotic treatment against colon cancer.

Bifidobacterium animalis subsp. lactis 420 for Metabolic Health: Review of the Research

The growing worldwide epidemic of obesity and associated metabolic health comorbidities has resulted in an urgent need for safe and efficient nutritional solutions. The research linking obesity with gut microbiota dysbiosis has led to a hypothesis that certain bacterial strains could serve as probiotics helping in weight management and metabolic health. In the search for such strains, the effect of Bifidobacterium animalis subsp. lactis 420 (B420) on gut microbiota and metabolic health, and the mechanisms of actions, has been investigated in a variety of in vitro, pre-clinical, and clinical studies. In this review, we aim to highlight the research on B420 related to obesity, metabolic health, and the microbiota. Current research supports the hypothesis that gut dysbiosis leads to an imbalance in the inflammatory processes and loss of epithelial integrity. Bacterial components, like endotoxins, that leak out of the gut can invoke low-grade, chronic, and systemic inflammation. This imbalanced state is often referred to as metabolic endotoxemia. Scientific evidence indicates that B420 can slow down many of these detrimental processes via multiple signaling pathways, as supported by mechanistic in vitro and in vivo studies. We discuss the connection of these mechanisms to clinical evidence on the effect of B420 in controlling weight gain in overweight and obese subjects. The research further indicates that B420 may improve the epithelial integrity by rebalancing a dysbiotic state induced by an obesogenic diet, for example by increasing the prevalence of lean phenotype microbes such as Akkermansia muciniphila. We further discuss, in the context of delivering the health benefits of B420: the safety and technological aspects of the strain including genomic characterization, antibiotic resistance profiling, stability in the product, and survival of the live probiotic in the intestine. In summary, we conclude that the clinical and preclinical studies on metabolic health suggest that B420 may be a potential candidate in combating obesity; however, further clinical studies are needed.

Mucosal cancer-associated microbes and anastomotic leakage after resection of colorectal carcinoma

BACKGROUND

Clinical and experimental evidence suggests that colorectal mucosal microbiota changes during colorectal carcinogenesis and may impair colorectal anastomotic wound healing. Thus, we hypothesized that amounts of colorectal cancer-associated microbes in colorectal tissue might be associated with anastomotic leakage after resection for colorectal carcinoma.

METHODS

We analyzed 256 fresh frozen tissues of colorectal cancer from patients who underwent elective colorectal resection and anastomosis. Amounts of colorectal cancer-associated microbes, including Fusobacterium nucleatum, Escherichia coli possessing the polyketide synthase (pks) gene cluster, Enterococcus faecalis, and Bifidobacterium genus, in colorectal cancer tissues were measured by quantitative polymerase chain reaction assay; we equally dichotomized positive cases (high versus low). Multivariable logistic regression analysis was conducted to assess associations of these microbes with anastomotic leakage, adjusting for patient and tumor characteristics, and surgery-related factors.

RESULTS

Fusobacterium nucleatum, pks-positive Escherichia coli, Enterococcus faecalis, and Bifidobacterium genus were detected in colorectal carcinoma tissue in 140 (54%), 94 (36%), 193 (75%), and 89 (35%) of 256 cases, respectively. Compared with Bifidobacterium genus-negative cases, Bifidobacterium genus-high cases were associated with an increased risk of anastomotic leakage (multivariable odds ratio, 3.96; 95% confidence interval, 1.50 to 10.51; P_trend = 0.004). The association of Fusobacterium nucleatum, pks-positive Escherichia coli, or Enterococcus faecalis with anastomotic leakage was not statistically significant.

CONCLUSIONS

The amount of Bifidobacterium genus in colorectal tissue is associated with an increased risk of anastomotic leakage after resection for colorectal cancer. These findings need to be validated to target gastrointestinal microflora for the prevention of anastomotic leakage after colorectal resection.

Biological Activities of Lactose-Based Prebiotics and Symbiosis with Probiotics on Controlling Osteoporosis, Blood-Lipid and Glucose Levels

Lactose-based prebiotics are synthesized by enzymatic- or microbial- biotransformation of lactose and have unique functional values. In this comprehensive review article, the biochemical mechanisms of controlling osteoporosis, blood-lipid, and glucose levels by lactose-based prebiotics and symbiosis with probiotics are reported along with the results of clinical investigations. Interaction between lactose-based prebiotics and probiotics reduces osteoporosis by (a) transforming insoluble inorganic salts to soluble and increasing their absorption to gut wall; (b) maintaining and protecting mineral absorption surface in the intestine; (c) increasing the expression of calcium-binding proteins in the gut wall; (d) remodeling osteoclasts and osteoblasts formation; (e) releasing bone modulating factors; and (f) degrading mineral complexing phytic acid. Lactose-based prebiotics with probiotics control lipid level in the bloodstream and tissue by (a) suppressing the expressions of lipogenic- genes and enzymes; (b) oxidizing fatty acids in muscle, liver, and adipose tissue; (c) binding cholesterol with cell membrane of probiotics and subsequent assimilation by probiotics; (d) enzymatic-transformations of bile acids; and (e) converting cholesterol to coprostanol and its defecation. Symbiosis of lactose-based prebiotics with probiotics affect plasma glucose level by (a) increasing the synthesis of gut hormones plasma peptide-YY, glucagon-like peptide-1 and glucagon-like peptide-2 from entero-endocrine L-cells; (b) altering glucose assimilation and metabolism; (c) suppressing systematic inflammation; (d) reducing oxidative stress; and (e) producing amino acids. Clinical investigations show that lactose-based prebiotic galacto-oligosaccharide improves mineral absorption and reduces hyperlipidemia. Another lactose-based prebiotic, lactulose, improves mineral absorption, and reduces hyperlipidemia and hyperglycemia. It is expected that this review article will be of benefit to food technologists and medical practitioners.

Biological Activities of Lactose-Derived Prebiotics and Symbiotic with Probiotics on Gastrointestinal System

Lactose-derived prebiotics provide wide ranges of gastrointestinal comforts. In this review article, the probable biochemical mechanisms through which lactose-derived prebiotics offer positive gastrointestinal health are reported along with the up-to-date results of clinical investigations; this might be the first review article of its kind, to the best of our knowledge. Lactose-derived prebiotics have unique biological and functional values, and they are confirmed as ‘safe’ by the Food and Drug Administration federal agency. Medical practitioners frequently recommend them as therapeutics as a pure form or combined with dairy-based products (yoghurt, milk and infant formulas) or fruit juices. The biological activities of lactose-derived prebiotics are expressed in the presence of gut microflora, mainly probiotics (Lactobacillus spp. in the small intestine and Bifidobacterium spp. in the large intestine). Clinical investigations reveal that galacto-oligosaccharide reduces the risks of several types of diarrhea (traveler’s diarrhea, osmotic diarrhea and Clostridium difficile associated relapsing diarrhea). Lactulose and lactosucrose prevent inflammatory bowel diseases (Crohn’s disease and ulcerative colitis). Lactulose and lactitol reduce the risk of hepatic encephalopathy. Furthermore, lactulose, galacto-oligosaccharide and lactitol prevent constipation in individuals of all ages. It is expected that the present review article will receive great attention from medical practitioners and food technologists.

Synthesis and purification of galacto-oligosaccharides: state of the art

Lactose-derived non-digestible oligosaccharides are prominent components of functional foods. Among them, galacto-oligosaccharides (GOS) outstand for being prebiotics whose health-promoting effects are supported on strong scientific evidences, having unique properties as substitutes of human milk oligosaccharides in formulas for newborns and infants. GOS are currently produced enzymatically in a kinetically-controlled reaction of lactose transgalactosylation catalyzed by β-galactosidases from different microbial strains. The enzymatic synthesis of GOS, although being an established technology, still offers many technological challenges and opportunities for further development that has to be considered within the framework of functional foods which is the most rapidly expanding market within the food sector. This paper presents the current technological status of GOS production, its main achievements and challenges. Most of the problems yet to be solved refer to the rather low GOS yields attainable that rarely exceed 40 %, corresponding to lactose conversions around 60 %. This means that the product or reaction (raw GOS) contains significant amounts of residual lactose and monosaccharides (glucose and galactose). Efforts to increase such yields have been for the most part unsuccessful, even though improvements by genetic and protein engineering strategies are to be expected in the near future. Low yields impose a burden on downstream processing to obtain a GOS product of the required purity. Different strategies for raw GOS purification are reviewed and their technological significance is appraised.

Structural Change in Microbiota by a Probiotic Cocktail Enhances the Gut Barrier and Reduces Cancer via TLR2 Signaling in a Rat Model of Colon Cancer

BACKGROUND

Structural change in the gut microbiota is implicated in cancer. The beneficial modulation of the microbiota composition with probiotics and prebiotics prevents diseases.

AIM

We investigated the effect of oligofructose-maltodextrin-enriched Lactobacillus acidophilus, Bifidobacteria bifidum, and Bifidobacteria infantum (LBB), on the gut microbiota composition and progression of colorectal cancer.

METHODS

Sprague Dawley rats were acclimatized, given ampicillin (75 mg/kg), and treated as follows; GCO: normal control; GPR: LBB only; GPC: LBB+ 1,2-dimethylhydrazine dihydrochloride (DMH); and GCA: DMH only (cancer control). 16S V4 Pyrosequencing for gut microbiota analysis, tumor studies, and the expression of MUC2, ZO-1, occludin, TLR2, TLR4, caspase 3, COX-2, and β-catenin were conducted at the end of experiment.

RESULTS

Probiotic LBB treatment altered the gut microbiota. The relative abundance of genera Pseudomonas, Congregibacter, Clostridium, Candidactus spp., Phaeobacter, Escherichia, Helicobacter, and HTCC was decreased (P < 0.05), but the genus Lactobacillus increased (P < 0.05), in LBB treatment than in cancer control. The altered gut microbiota was associated with decreased tumor incidence (80 % in GPC vs. 100 % in GCA, P = 0.0001), tumor volume (GPC 84.23 (42.75-188.4) mm(3) vs. GCA 243 (175.5-344.5) mm(3), P < 0.0001) and tumor multiplicity/count (GPC 2.92 ± 0.26 vs. GCA 6.27 ± 0.41; P < 0.0001). The expression of MUC2, ZO-1, occludin, and TLR2 was increased, but expression of TLR4, caspase 3, Cox-2, and β-catenin was decreased by LBB treatment than in cancer control GCA (P < 0.05).

CONCLUSION

Administration of LBB modulates the gut microbiota and reduces colon cancer development by decreasing tumor incidence, multiplicity/count, and volume via enhanced TLR2-improved gut mucosa epithelial barrier integrity and suppression of apoptosis and inflammation.

Cellular and molecular effects of yeast probiotics on cancer

The cancer is one of the main causes of human deaths worldwide. The exact mechanisms of initiation and progression of malignancies are not clear yet, but there is a common agreement about the role of colonic microbiota in the etiology of different cancers. Probiotics have been examined for their anti-cancer effects, and different mechanisms have been suggested about their antitumor functions. Nonpathogenic yeasts, as members of probiotics family, can be effective on gut microbiota dysbiosis. Generally safe yeasts have shown so many beneficial effects on human health. Probiotic yeasts influence physiology, metabolism, and immune homeostasis in the colon and contribute to cancer treatment due to possessing anti-inflammatory, anti-proliferative and anti-cancer properties. This study reviews some of the health-beneficial effects of probiotic yeasts and their biological substances like folic acid and β-glucan on cancer and focuses on the possible cellular and molecular mechanisms of probiotic yeasts such as influencing pathogenic bacteria, inactivation of carcinogenic compounds, especially those derived from food, improvement of intestinal barrier function, modulation of immune responses, antitoxic function, apoptosis, and anti-proliferative effects.

The Potential Role of Probiotics in Cancer Prevention and Treatment

The human gut microbiota has a significant effect on many aspects of human physiology such as metabolism, nutrient absorption, and immune function. Imbalance of the microbiota has been implicated in many disorders including inflammatory bowel disease, obesity, asthma, psychiatric illnesses, and cancers. As a kind of functional foods, probiotics have been shown to play a protective role against cancer development in animal models. Clinical application of probiotics indicated that some probiotic strains could diminish the incidence of postoperative inflammation in cancer patients. Chemotherapy or radiotherapy-related diarrhea was relieved in patients who were administered oral probiotics. The present review summarizes the up-to-date studies on probiotic effects and the underlying mechanisms related to cancer. At present, it is commonly accepted that most commercial probiotic products are generally safe and can improve the health of the host. By modulating intestinal microbiota and immune response, some strains of probiotics can be used as an adjuvant for cancer prevention or/and treatment.

Gut Function-Enhancing Properties and Metabolic Effects of Dietary Indigestible Sugars in Rodents and Rabbits

Indigestible sugars (iS) have received particular interest in food and nutrition research due to their prebiotic properties and other health benefits in humans and animals. The main aim of this review article is to summarize the current knowledge regarding digestive and health-enhancing properties of iS such as sugar alcohols, oligosacharides, and polysaccharides, in rodents and rabbits. Besides ameliorating gut health, iS ingestion also elicits laxative effects and stimulate intestinal permeability and fluid secretions, thereby shortening digesta transit time and increasing stool mass and quality. In rodents and rabbits, as hindgut fermenters, consumption of iS leads to an improved nutrient digestibility, too. Cecal fermentation of iS reduces luminal pH and extends wall tissue facilitating absorption of key dietary minerals across hindgut. The microbial fermentation of iS also enhances excessive blood nitrogen (N) flowing into the cecum to be used as N source for bacterial growth, enhancing N retention in cecotrophic animals. This review also highlights the impact of iS on improving lipid metabolism, mainly by lowering cholesterol and triglycerides levels in the blood. The paper serves as an index of the current knowledge of iS effects in rodents and rabbits and also identifies gaps of knowledge that need to be addressed by future research.

Feeding probiotic Lactobacillus rhamnosus (MTCC 5897) fermented milk to suckling mothers alleviates ovalbumin-induced allergic sensitisation in mice offspring

The neonatal period is often polarised to T helper (Th2) response at the time of birth, predisposing offspring to allergic disorders. Passive immunity through the mother's milk is critical for immune system development of newborns. Probiotics have been proposed to harmonise Th1/Th2 imbalance in allergic conditions in adults. In the present study, the anti-allergic effects of feeding probiotic Lactobacillus rhamnosus-fermented milk (PFM) either to dams during the suckling period or to their offspring after weaning individually or else in successive periods against ovalbumin (OVA)-induced allergy in newborns was analysed. After allergen sensitisation, physical symptoms of allergy, gut immune response, humoral immune response and cell-mediated response through interleukins were detected. Consumption of PFM by mothers and offspring showed a reduction (P<0·01) in physical allergic symptoms in newborns with an increase (P<0·01) in the numbers of goblet and IgA+ cells in the small intestine. Similarly, considerable (P<0·001) decreases in OVA-specific antibodies (IgE, IgG, IgG1) and ratios of IgE/IgG2a and IgG1/IgG2a in the sera of newborn mice were recorded. A decrease in IL-4 and an increase in interferon-γ levels further confirmed the shift from Th2 to Th1 pathway in PFM-fed mice. It is logical to conclude that the timing of PFM intervention in alleviating allergic symptoms is critical, which was found to be most effective when mothers were fed during the suckling period.

Engineered in vitro disease models

The ultimate goal of most biomedical research is to gain greater insight into mechanisms of human disease or to develop new and improved therapies or diagnostics. Although great advances have been made in terms of developing disease models in animals, such as transgenic mice, many of these models fail to faithfully recapitulate the human condition. In addition, it is difficult to identify critical cellular and molecular contributors to disease or to vary them independently in whole-animal models. This challenge has attracted the interest of engineers, who have begun to collaborate with biologists to leverage recent advances in tissue engineering and microfabrication to develop novel in vitro models of disease. As these models are synthetic systems, specific molecular factors and individual cell types, including parenchymal cells, vascular cells, and immune cells, can be varied independently while simultaneously measuring system-level responses in real time. In this article, we provide some examples of these efforts, including engineered models of diseases of the heart, lung, intestine, liver, kidney, cartilage, skin and vascular, endocrine, musculoskeletal, and nervous systems, as well as models of infectious diseases and cancer. We also describe how engineered in vitro models can be combined with human inducible pluripotent stem cells to enable new insights into a broad variety of disease mechanisms, as well as provide a test bed for screening new therapies.

Immunomodulatory activity of two potential probiotic strains in LPS-stimulated HT-29 cells

The relative expression of mucin, pro- and anti-inflammatory genes besides other signaling molecules in HT-29 cells by two test probiotic strains of Lactobacillus plantarum Lp9 and Lp91 and the reference strain L. plantarum 5276 was evaluated by RT-qPCR using Relative Expression Software Tool qBase-Plus under in vitro simulated gut conditions. Ten house keeping genes were evaluated by using geNorm 3.4 excel based application. The most stable genes were RPL27, ACTB and B2M which were subsequently used for calculating the normalization factor. Under pretreatment conditions (4 h probiotic treatment, followed by lipopolysaccharide challenge for 3 h), all the three strains evoked downregulation of IL-8 expression by ~100 %, while in case of TNF-α, the downregulation of the relative gene expression was at the rate of 98.2, 93.8 and 98.0 % with Lp5276, Lp9 and Lp91, respectively, under the same set of conditions. Lp91 evoked maximum downregulation of IL12p35 and IFN-γ with corresponding fold reduction in relative expression of the two genes by 96.5 and 96.7 % during pre-treatment conditions. However, IL-10 and IFN-α were significantly upregulated to the extent of 8.13 ± 0.36 and 2.62 ± 0.14 fold by Lp91 under the same conditions. Lp9 and Lp91 were also quite effective in inducing the expression of Cox-1 and Cox-2 in HT-29 cells as can be reflected from their ratios, i.e., 5.90 and 6.50 (under pretreatment conditions); 3.79 and 4.36 (under co-culture conditions). Thus, the two putative indigenous L. plantarum strains Lp9 and Lp91 demonstrated immunomodulating functions in HT-29 cells at significant levels under different experimental conditions.

Escherichia coli Nissle 1917-derived factors reduce cell death and late apoptosis and increase transepithelial electrical resistance in a model of 5-fluorouracil-induced intestinal epithelial cell damage

We evaluated the capacity for supernatants (SNs) derived from Escherichia coli Nissle 1917 (EcN), cultured under different growth conditions, to prevent 5-fluorouracil (5-FU)-induced intestinal epithelial cell damage. EcN was cultured in: Luria Bertani (LB) broth, tryptone soya broth (TSB), de Man Rogosa Sharpe (MRS) broth, and M17 broth supplemented with 10% (v/v) lactose solution (M17). Intestinal epithelial cells (IEC-6) were treated with the following EcN SNs: LB(+), TSB(+), MRS(+), and M17(+) in the presence and absence of 5-FU (1.5 or 5 μM). Cell viability, apoptotic activity and cell monolayer permeability were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, and transepithelial electrical resistance (TER) assays, respectively. 5-FU significantly reduced cell viability (P<0.05) at both 24 and 48 h. However, only EcN SN produced from LB and M17 growth media significantly decreased cell death induced by 5-FU (by approximately 10% after 24 and 48 h; and 10% after 24 h, respectively [P<0.05]). When measured by flow cytometry all EcN SNs in the presence of 5-FU increased the proportion of viable cells (by 3-5% for 24 h, 3-7% for 48 h, P<0.05) and reduced late-apoptotic cells after 24 and 48 h, compared with 5-FU control. Moreover, all EcN SNs significantly reduced the disruption of IEC-6 cell barrier function induced by 5-FU by 7-10% (P<0.05), compared with DMEM control. We conclude that EcN derived factors could potentially reduce the severity of intestinal mucositis.

Cytokine expression in head-kidney leucocytes of European sea bass (Dicentrarchus labrax L.) after incubation with the probiotic Vagococcus fluvialis L-21

The European sea bass (Dicentrarchus labrax L.) is one of the most extensively farmed marine fish in the Mediterranean sea. Under the high-density condition, common in aquaculture, the infectious diseases can cause significant economic losses. Probiotics are presented as an alternative to antibiotics for the control of aquaculture diseases. This study used real-time PCR to investigate in vitro the dynamic of expression of immune-related genes in sea bass after incubation with live and inactivated (heat and Uv-light) probiotic Vagoccus fluvialis L-21 at different times (T1, T12, T24, T48). The immune associated genes, interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin 10 (IL-10), TumourTumour necrosis factor- (TNF-), ciclo-oxigenase-2 (COX-2), caspase-3 (Casp-3) and Mx were studied in head-kidney (HK) leucocytes of sea bass after incubation with the probiotic strain. Transcript of proinflammatory cytokines (IL-1, TNF-, COX-2) was highly up-regulated after 1 h of incubation with the probiotic strain V. fluvialis L-21. We found statistically significant difference in pick of expression of TNF-, after 1 h of incubation with Uv-light inactivated probiotic strain. The COX-2 expression was highly up-regulated at all times studied, with the exception of 12 and 24 h post incubation for the Uv-light inactivated bacteria. Transcript of IL-10 and Casp-3 showed the higher statistically significant differences of expression after 48 h post incubation with live bacteria. In the contrast, sea bass HK leucocytes expressed Mx at 12 and 48 h without statistically differences among treatments. Our results suggest that V. fluvialis L-21 is able to stimulate in vitro some immune-related genes associated with the early inflammatory response. Future studies in vivo are necessary to clarify this process in sea bass.

Plant cell wall polysaccharides as potential resources for the development of novel prebiotics

Prebiotic oligosaccharides, with a degree of polymerization (DP) of mostly less than 10, exhibit diverse biological activities that contribute to human health. Currently available prebiotics are mostly derived from disaccharides and simple polysaccharides found in plants. Subtle differences in the structures of oligosaccharides can cause significant differences in their prebiotic proper-ties. Therefore, alternative substances supplying polysaccharides that have more diverse and complex structures are necessary for the development of novel oligosaccharides that have actions not present in existing prebiotics. In this review, we show that structural polysaccharides found in plant cell walls, such as xylans and pectins, are particularly potential resources supplying broadly diverse polysaccharides to produce new prebiotics.

Investigation of STW 5 (Iberogast®) preventive effects in experimental sepsis

CONTEXT

STW 5 (Iberogast(®)) is a well known herbal combination drug containing glycosides and flavonoids for which multiple pharmacological properties have been shown.

OBJECTIVE

In this study, attempts were made to assess whether STW 5, an aqueous ethanol solution, has a preventive effect against liver and lung pathological damage in rats after experimental induction of sepsis [cecal ligation and puncture (CLP)].

MATERIALS AND METHODS

Experimental sepsis was induced in rats using CLP operation. The rats (n = 36) were divided into six groups (six/group): Sham-operated (SOP); CLP; CLP + STW 5 (2.5, 5 and 10 mg/kg) and CLP + indomethacin. The drugs were injected intraperitoneally immediately after sepsis induction.

RESULTS

It was found that induction of sepsis 24 h after CLP was associated with significant liver and lung damage, also remaining after STW 5 administration.

DISCUSSION AND CONCLUSION

It appears that STW 5, which has a pronounced efficacy in functional gastro-intestinal diseases, has no effect on septic liver and lung damage in the CLP rat model.

Bifidobacterium animalis ssp. lactis 420 Protects against Indomethacin-Induced Gastric Permeability in Rats

Gastrointestinal (GI) adverse effects such as erosion and increased permeability are common during the use of nonsteroidal anti-inflammatory drugs (NSAIDs). Our objective was to assess whether Bifidobacterium animalis ssp. lactis 420 protects against NSAID-induced GI side effects in a rat model. A total of 120 male Wistar rats were allocated into groups designated as control, NSAID, and probiotic. The NSAID and probiotic groups were challenged with indomethacin (10 mg/kg(-1); single dose). The probiotic group was also supplemented daily with 10(10) CFU of B. lactis 420 for seven days prior to the indomethacin administration. The control group rats received no indomethacin or probiotic. The permeability of the rat intestine was analysed using carbohydrate probes and the visual damage of the rat stomach mucosa was graded according to severity. B. lactis 420 significantly reduced the indomethacin-induced increase in stomach permeability. However, the protective effect on the visual mucosal damage was not significant. The incidence of severe NSAID-induced lesions was, nevertheless, reduced from 50% to 33% with the probiotic treatment. To conclude, the B. lactis 420 supplementation protected the rats from an NSAID-induced increase in stomach permeability and may reduce the formation of more serious GI mucosal damage and/or enhance the recovery rate of the stomach mucosa.

Impact of polydextrose on the faecal microbiota: a double-blind, crossover, placebo-controlled feeding study in healthy human subjects

In this placebo-controlled, double-blind, crossover human feeding study, the effects of polydextrose (PDX; 8 g/d) on the colonic microbial composition, immune parameters, bowel habits and quality of life were investigated. PDX is a complex glucose oligomer used as a sugar replacer. The main goal of the present study was to identify the microbial groups affected by PDX fermentation in the colon. PDX was shown to significantly increase the known butyrate producer Ruminococcus intestinalis and bacteria of the Clostridium clusters I, II and IV. Of the other microbial groups investigated, decreases in the faecal Lactobacillus-Enterococcus group were demonstrated. Denaturing gel gradient electrophoresis analysis showed that bacterial profiles between PDX and placebo treatments were significantly different. PDX was shown to be slowly degraded in the colon, and the fermentation significantly reduced the genotoxicity of the faecal water. PDX also affected bowel habits of the subjects, as less abdominal discomfort was recorded and there was a trend for less hard and more formed stools during PDX consumption. Furthermore, reduced snacking was observed upon PDX consumption. This study demonstrated the impact of PDX on the colonic microbiota and showed some potential for reducing the risk factors that may be associated with colon cancer initiation.

The intestinal microbiota, gastrointestinal environment and colorectal cancer: a putative role for probiotics in prevention of colorectal cancer?

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the United States, and, even though 5-15% of the total CRC cases can be attributed to individual genetic predisposition, environmental factors could be considered major factors in susceptibility to CRC. Lifestyle factors increasing the risks of CRC include elevated body mass index, obesity, and reduced physical activity. Additionally, a number of dietary elements have been associated with higher or lower incidence of CRC. In this context, it has been suggested that diets high in fruit and low in meat might have a protective effect, reducing the incidence of colorectal adenomas by modulating the composition of the normal nonpathogenic commensal microbiota. In addition, it has been demonstrated that changes in abundance of taxonomic groups have a profound impact on the gastrointestinal physiology, and an increasing number of studies are proposing that the microbiota mediates the generation of dietary factors triggering colon cancer. High-throughput sequencing and molecular taxonomic technologies are rapidly filling the knowledge gaps left by conventional microbiology techniques to obtain a comprehensive catalog of the human intestinal microbiota and their associated metabolic repertoire. The information provided by these studies will be essential to identify agents capable of modulating the massive amount of gut bacteria in safe noninvasive manners to prevent CRC. Probiotics, defined as "live microorganisms which, when administered in adequate amounts, confer a health benefit on the host" (219), are capable of transient modulation of the microbiota, and their beneficial effects include reinforcement of the natural defense mechanisms and protection against gastrointestinal disorders. Probiotics have been successfully used to manage infant diarrhea, food allergies, and inflammatory bowel disease; hence, the purpose of this review was to examine probiotic metabolic activities that may have an effect on the prevention of CRC by scavenging toxic compounds or preventing their generation in situ. Additionally, a brief consideration is given to safety evaluation and production methods in the context of probiotics efficacy.

Probiotics and small bowel mucosa: Molecular aspects of their interactions

Probiotics are described as "friendly bacteria" that could improve the intestine defense by interacting with the resident microflora. There is a large body of evidence suggesting that consumption of functional food containing probiotics exerts positive effects on human health. Several clinical trials have highlighted the efficiency of probiotics in the prevention and treatment of different gastrointestinal disorders including the prevention of antibiotic associated diarrhea, the remission in patients with inflammatory bowel disease, beneficial effects against Helicobacter pylori infection, positive effects in patients affected by allergies and atopic diseases. The clinical benefits of probiotics use are mainly attributed to their antimicrobial substances production and their positive interactions with the enterocytes to reinforce the intestinal epithelial barrier. Moreover, there is evidence suggesting that probiotics stimulate both specific and non-specific host immune responses. Recently, have been published some experiments performed with the DNA microarray technology which provided a global gene screening of the complex bacteria-host interplay. Nevertheless, the molecular mechanisms by which probiotics enhance the intestinal host defense are still not completely elucidated. Here, we review the experiments and clinical studies to date on the complex mechanisms regulating the communication between probiotics and their hosts.

Bifidobacterium lactis inhibits NF-kappaB in intestinal epithelial cells and prevents acute colitis and colitis-associated colon cancer in mice

BACKGROUND

The aim of this study was to investigate the antiinflammatory effects of Bifidobacterium lactis on intestinal epithelial cells (IECs) and on experimental acute murine colitis and its tumor prevention effects on colitis-associated cancer (CAC) in mice.

METHODS

Human HT-29 cells were stimulated with IL-1beta, lipopolysaccharides, or tumor necrosis factor-alpha with and without B. lactis, and the effects of B. lactis on nuclear factor kappa B (NF-kappaB) signaling in IEC were examined. For in vivo study, dextran sulfate sodium (DSS)-treated mice were fed with and without B. lactis. Finally, we induced colonic tumors in mice by azoxymethane (AOM) and DSS and evaluated the effects of B. lactis on tumor growth.

RESULTS

B. lactis significantly suppressed NF-kappaB activation, including NF-kappaB-binding activity and NF-kappaB-dependent reporter gene expression in a dose-dependent manner, and suppressed IkappaB-alpha degradation, which correlated with the downregulation of NF-kappaB-dependent gene products. Moreover, B. lactis suppressed the development of acute colitis in mice. Compared with the DSS group, the severity of DSS-induced colitis as assessed by disease activity index, colon length, and histological score was reduced in the B. lactis-treated group. In the CAC model, the mean number and size of tumors in the B. lactis-treated group were significantly lower than those in the AOM group.

CONCLUSIONS

Our data demonstrate that B. lactis inhibits NF-kappaB and NF-kappaB-regulated genes in IEC and prevents acute colitis and CAC in mice. These results suggest that B. lactis could be a potential preventive agent for CAC as well as a therapeutic agent for inflammatory bowel disease.

Probiotics and immunity: a fish perspective

Probiotics are usually live microorganisms which when administered in adequate amounts confer a health benefits on host. Nowadays, probiotics are also becoming an integral part of the aquaculture practices to obtain high production. The common probiotics that are used for aquaculture practices include Lactobacillus, Lactococcus, Leuconostoc, Enterococcus, Carnobacterium, Shewanella, Bacillus, Aeromonas, Vibrio, Enterobacter, Pseudomonas, Clostridium, and Saccharomyces species. The involvement of probiotics in nutrition, disease resistance and other beneficial activities in fish has proven beyond any doubt. Among the numerous health benefits attributed to probiotics, modulation of immune system is one of the most commonly purported benefits of the probiotics and their potency to stimulate the systemic and local immunity under in vitro and in vivo conditions is noteworthy. Different probiotics either monospecies or multispecies supplementation can eventually elevate phagocytic, lysozyme, complement, respiratory burst activity as well as expression of various cytokines in fish. Similarly, probiotics can stimulate the gut immune system of fish with marked increase in the number of Ig(+) cells and acidophilic granulocytes. Furthermore, mono-bacterial association studies (with non-probiotic bacterial strains) in gnotobiotic fish also indicate the up-regulation of various immune related genes. Though the exact mode of action of probiotics is yet to be established in any animal including fish, probiotics often exert host specific and strain specific differences in their activities. Various factors like source, type, dose and duration of supplementation of probiotics can significantly affect the immunomodulatory activity of probiotics. The review is therefore, aiming to highlight the immunomodulatory activity of probiotics and also to evaluate the factors that regulate for the optimum induction of immune responses in fish.

Lactobacillus casei: influence on the innate immune response and haemostatic alterations in a liver-injury model

Lactobacilllus casei CRL 431 has the ability to modulate the local and systemic immune responses, which are significantly involved in liver injury caused by hepatotoxins. This work was conducted to determine whether L. casei has a preventive effect on the hepatic damage undergone during an acute liver injury (ALI).

METHODS

ALI was induced by an intraperitoneal injection of d-galactosamine (D-Gal). Different groups of mice received 1x 109 L. casei cells/day/mouse for 2 days before D-Gal injection. Blood and liver samples were obtained 0, 6, 12, and 24 h after D-Gal administration.

RESULTS

D-Gal induced increases in serum aminotransferases, reduced the number of blood leukocytes, enhanced neutrophil myeloperoxidase activity, increased dead cells, and altered prothrombin time and plasma fibrinogen levels. The preventive treatment with L. casei for 2 days modulated the innate immune response. This effect was shown by the earlier normalization of white blood cell counts, myeloperoxidase activity and aminotransferases levels. However, the haemostatic parameters were only partially recovered. The favourable effects obtained could be due to the capacity of L. casei to moderate the inflammatory response at the site of the injury with less damage to liver tissue.

Lactobacillus acidophilus 74-2 and butyrate induce cyclooxygenase (COX)-1 expression in gastric cancer cells

Cyclo-oxygenase (COX) profile predicts prognosis of gastric cancer; COX-2 positive tumors are more often aggressive, and COX-2 suppression is protective against gastric cancer. In contrast, COX-1 suppression is harmful to the intestinal mucosa. The COX-1, COX-2, and COX-1ir expression profiles were measured with real-time PCR in primary (AGS) and metastatic (NCI-N87) gastric adenocarcinoma cell lines treated with butyrate, hyperosmolar medium, and, in the case of NCI-N87, cell-free supernatants of probiotic bacteria Lactobacillus acidophilus 74-2 and Bifidobacterium lactis 420. The cell lines showed differences in the profile when treated with either hyperosmolar medium or butyrate. In NCI-N87 COX-2 expression was higher but only COX-1 expression was significantly upregulated by butyrate. Similarly to butyrate, the cell-free supernatant of L. acidophilus 74-2 upregulated COX-1, while COX-2 expression remained unchanged. COX-1ir, including COX-3, was upregulated by probiotics and osmotic stress. In conclusion, consumption of L. acidophilus 74-2 could be beneficial for the expression of cytoprotective COX-1.

Indications and challenges of probiotics, prebiotics, and synbiotics in the management of arthralgias and spondyloarthropathies in inflammatory bowel disease

Arthralgia and spondyloarthropathy of the peripheral and the axial joints are common in patients with inflammatory bowel diseases. Evidence for this association has been provided by clinical, epidemiologic, and immunologic studies confirming the presence of shared inflammatory pathways in gut and joint. Bacterial gut infections such as Salmonella typhimurium, Yersinia enterocolitica, Shigella, Campylobacter jejuni may induce reactive peripheral arthritis and 20% of these patients may develop chronic spondyloarthropathy. It is not certain that arthralgias in inflammatory bowel diseases are more frequent than in the general population but clinical articular manifestations compatible with spondyloarthropathy are present in 10% to 40% of patients with inflammatory bowel diseases. These enteropathic peripheral arthropathies without axial involvement are subdivided into a pauciarticular of large joints and a bilateral symmetrical polyarthropathy. The rationale and the challenges of using prebiotics, probiotics, and synbiotics in the management of patients with inflammatory bowel diseases with arthralgias and spondyloarthropathy are briefly reviewed. The rationale is based on the modulation of the ubiquitous intestinal flora by bacteria and their products that have been proven to be safe. The challenge is to find the "window of opportunity" to treat the evolutionary stage of joint inflammation. It seems to us that the major aim is not to treat patients who have a self-limited inflammatory joint disorder, but those patients with persistent arthralgias in an early phase of the disease. Seronegative and seropositive patients with early arthritis, before damage may occur, could be managed by this approach to improve the quality of life and to positively influence the natural course of the disease.

Effect of four probiotic strains and Escherichia coli O157:H7 on tight junction integrity and cyclo-oxygenase expression

Controversy exists as to whether contact between a probiotic bacterial cell and an epithelial cell in the gut is needed to confer beneficial effects of probiotics, or whether metabolites from probiotics are sufficient to cause this effect. To address this question, Caco-2 cells were treated with cell-free supernatants of four probiotics, Bifidobacterium lactis 420, Bifidobacterium lactis HN019, Lactobacillus acidophilus NCFM, Lactobacillus salivarius Ls-33, and by a cell-free supernatant of a pathogenic bacteria, Escherichia coli O157:H7 (EHEC). Tight junction integrity as well as expression of cyclo-oxygenases, which are prostaglandin-producing enzymes, were measured. Probiotic-specific as well as EHEC-specific effects on tight junction integrity and cyclo-oxygenase expression were evident, indicating that live bacterial cells were not necessary for the manifestation of the effects. B. lactis 420 cell-free supernatant increased tight junction integrity, while EHEC cell-free supernatant induced damage on tight junctions. In general, EHEC and probiotics had opposite effects upon cyclo-oxygenase expression. Furthermore, B. lactis 420 cell-free supernatant protected the tight junctions from EHEC-induced damage when administered prior to the cell-free supernatant of EHEC. These results indicate that probiotics produce bioactive metabolites, suggesting that consumption of specific probiotic bacteria might be beneficial in protecting intestinal epithelial cells from the deleterious effects of pathogenic bacteria.

Bacterial metabolism and health-related effects of galacto-oligosaccharides and other prebiotics

Most studies involving prebiotic oligosaccharides have been carried out using inulin and its fructo-oligosaccharide (FOS) derivatives, together with various forms of galacto-oligosaccharides (GOS). Although many intestinal bacteria are able to grow on these carbohydrates, most investigations have demonstrated that the growth of bifidobacteria, and to a lesser degree lactobacilli, is particularly favoured. Because of their safety, stability, organoleptic properties, resistance to digestion in the upper bowel and fermentability in the colon, as well as their abilities to promote the growth of beneficial bacteria in the gut, these prebiotics are being increasingly incorporated into the Western diet. Inulin-derived oligosaccharides and GOS are mildly laxative, but can result in flatulence and osmotic diarrhoea if taken in large amounts. However, their effects on large bowel habit are relatively minor. Although the literature dealing with the health significance of prebiotics is not as extensive as that concerning probiotics, considerable evidence has accrued showing that consumption of GOS and FOS can have significant health benefits, particularly in relation to their putative anti-cancer properties, influence on mineral absorption, lipid metabolism, and anti-inflammatory and other immune effects such as atopic disease. In many instances, prebiotics seem to be more effective when used as part of a synbiotic combination.

Live probiotic Bifidobacterium lactis bacteria inhibit the toxic effects induced by wheat gliadin in epithelial cell culture

Wheat gliadin induces severe intestinal symptoms and small-bowel mucosal damage in coeliac disease patients. At present, the only effective treatment for the disease is a strict life-long gluten-free diet. In this study we investigated whether probiotics Lactobacillus fermentum or Bifidobacterium lactis can inhibit the toxic effects of gliadin in intestinal cell culture conditions. The ability of live probiotics to inhibit peptic-tryptic digested gliadin-induced damage to human colon cells Caco-2 was evaluated by measuring epithelial permeability by transepithelial resistance, actin cytoskeleton arrangements by the extent of membrane ruffling and expression of tight junctional protein ZO-1. B. lactis inhibited the gliadin-induced increase dose-dependently in epithelial permeability, higher concentrations completely abolishing the gliadin-induced decrease in transepithelial resistance. The same bacterial strain also inhibited the formation of membrane ruffles in Caco-2 cells induced by gliadin administration. Furthermore, it also protected the tight junctions of Caco-2 cells against the effects of gliadin, as evinced by the pattern of ZO-1 expression. We conclude thus that live B. lactis bacteria can counteract directly the harmful effects exerted by coeliac-toxic gliadin and would clearly warrant further studies of its potential as a novel dietary supplement in the treatment of coeliac disease.

The effect of probiotic fermented milk and inulin on the functions and microecology of the intestine

We investigated the effects of a probiotic fermented milk and inulin on gastrointestinal function and microecology. The study was double-blinded and comprised 66 healthy adults (22 male, 44 female), mean age 40 years (range, 22-60 years). After a 12-d baseline period the subjects were randomized to consume, for 3 weeks, 3x200 ml daily of either (1) a fermented milk with probiotics (Bifidobacterium longum BB536, Bifidobacterium spp. 420 and Lactobacillus acidophilus 145), (2) a fermented milk with the same probiotics plus 4 g inulin, or (3) a control fermented milk. During the last 7 d of the baseline and the intervention periods, the subjects kept a record of their defaecation frequency and gastrointestinal symptoms, and collected all their faeces. Intestinal transit time, stool weight and faecal enzyme activities were measured. Thirty-nine subjects were randomized to give faecal samples for analysis of pH and microbes, including lactobacilli, bifidobacteria, coliforms, Escherichia coli, Bacteroides and Clostridium perfringens. Consumption of fermented milk with probiotics or with probiotics and inulin increased the faecal number of lactobacilli (P=0.009, P=0.003) and bifidobacteria (P=0.046, P=0.038) compared with the baseline. Compared with the control fermented milk, both active products increased lactobacilli (P=0.005, ANCOVA). Subjects consuming fermented milk with probiotics and inulin suffered from gastrointestinal symptoms, especially flatulence, more than the others (P<0.001). In conclusion, the probiotic fermented milk product had a positive effect by increasing the number of lactobacilli and bifidobacteria in the colon. Inulin did not alter this effect but it increased gastrointestinal symptoms.

Effect of polydextrose on intestinal microbes and immune functions in pigs

Dietary fibre has been proposed to decrease risk for colon cancer by altering the composition of intestinal microbes or their activity. In the present study, the changes in intestinal microbiota and its activity, and immunological characteristics, such as cyclo-oxygenase (COX)-2 gene expression in mucosa, in pigs fed with a high-energy-density diet, with and without supplementation of a soluble fibre (polydextrose; PDX) (30 g/d) were assessed in different intestinal compartments. PDX was gradually fermented throughout the intestine, and was still present in the distal colon. Irrespective of the diet throughout the intestine, of the four microbial groups determined by fluorescentin situhybridisation, lactobacilli were found to be dominating, followed by clostridia andBacteroides. Bifidobacteria represented a minority of the total intestinal microbiota. The numbers of bacteria increased approximately ten-fold from the distal small intestine to the distal colon. Concomitantly, also concentrations of SCFA and biogenic amines increased in the large intestine. In contrast, concentrations of luminal IgA decreased distally but the expression of mucosal COX-2 had a tendency to increase in the mucosa towards the distal colon. Addition of PDX to the diet significantly changed the fermentation endproducts, especially in the distal colon, whereas effects on bacterial composition were rather minor. There was a reduction in concentrations of SCFA and tryptamine, and an increase in concentrations of spermidine in the colon upon PDX supplementation. Furthermore, PDX tended to decrease the expression of mucosal COX-2, therefore possibly reducing the risk of developing colon cancer-promoting conditions in the distal intestine.