Using Probiotics in Gastrointestinal Disorders

In vivo evaluation of an innovative synbiotics on stage IIIb-IV chronic kidney disease patients

Background

Microbiota unbalance has been proven to affect chronic kidney disease (CKD) patients and, noteworthy, microbiota composition and activity are implicated in CKD worsening. The progression of kidney failure implies an exceeding accumulation of waste compounds deriving from the nitrogenous metabolism in the intestinal milieu. Therefore, in the presence of an altered intestinal permeability, gut-derived uremic toxins, i.e., indoxyl sulfate (IS) and p-cresyl sulfate (PCS), can accumulate in the blood.

Methods

In a scenario facing the nutritional management as adjuvant therapy, the present study assessed the effectiveness of an innovative synbiotics for its ability to modulate the patient gut microbiota and metabolome by setting a randomized, single-blind, placebo-controlled, pilot trial accounting for IIIb-IV stage CKD patients and healthy controls. Metataxonomic fecal microbiota and fecal volatilome were analyzed at the run-in, after 2 months of treatment, and after 1 month of wash out.

Results

Significant changes in microbiota profile, as well as an increase of the saccharolytic metabolism, in feces were found for those CKD patients that were allocated in the synbiotics arm.

Conclusions

Noteworthy, the here analyzed data emphasized a selective efficacy of the present synbiotics on a stage IIIb-IV CKD patients. Nonetheless, a further validation of this trial accounting for an increased patient number should be considered.

Clinical trial registration

https://clinicaltrials.gov/, identifier NCT03815786.

Assessing the drug resistance profiles of oral probiotic lozenges

Background

Probiotic lozenges have been developed to harvest the benefits of probiotics for oral health, but their long-term consumption may encourage the transfer of resistance genes from probiotics to commensals, and eventually to disease-causing bacteria.

Aim

To screen commercial probiotic lozenges for resistance to antibiotics, characterize the resistance determinants, and examine their transferability in vitro.

Results

Probiotics of all lozenges were resistant to glycopeptide, sulfonamide, and penicillin antibiotics, while some were resistant to aminoglycosides and cephalosporins. High minimum inhibitory concentrations (MICs) were detected for streptomycin (>128 µg/mL) and chloramphenicol (> 512 µg/mL) for all probiotics but only one was resistant to piperacillin (MIC = 32 µg/mL). PCR analysis detected erythromycin (erm(T), ermB or mefA) and fluoroquinolone (parC or gyr(A)) resistance genes in some lozenges although there were no resistant phenotypes. The dfrD, cat-TC, vatE, aadE, vanX, and aph(3")-III or ant(2")-I genes conferring resistance to trimethoprim, chloramphenicol, quinupristin/dalfopristin, vancomycin, and streptomycin, respectively, were detected in resistant probiotics. The rifampicin resistance gene rpoB was also present. We found no conjugal transfer of streptomycin resistance genes in our co-incubation experiments.

Conclusion

Our study represents the first antibiotic resistance profiling of probiotics from oral lozenges, thus highlighting the health risk especially in the prevailing threat of drug resistance globally.

Protective effect of Bifidobacterium bifidum FSDJN7O5 and Bifidobacterium breve FHNFQ23M3 on diarrhea caused by enterotoxigenic Escherichia coli

Enterotoxigenic Escherichia coli (ETEC) is the main bacterial cause of diarrhea among children in developing countries and of traveler's diarrhea. In this study, a mouse model was used to evaluate the effect of Bifidobacterium on alleviating diarrhea caused by ETEC. The results showed that B. breve FHNFQ23M3 and B. bifidum FSDJN7O5 could relieve the symptoms of diarrhea. Both strains significantly reduced the stool water content, restored the villi structure in the jejunum and ameliorated the fecal short-chain fatty acid (SCFA) content. In addition, B. breve FHNFQ23M3 restored body weight to the level before ETEC challenge and significantly reduced interferon-γ (IFN-γ), while B. bifidum FSDJN7O5 significantly improved interleukin (IL)-10. Furthermore, all the Bifidobacterium strains used in this study could significantly downregulate tumor necrosis factor-α (TNF-α) and restore the unbalanced gut microbiota, which had a high content of pathogenic Escherichia-Shigella and low content of Blautia and Clostridium innocuum groups due to ETEC. All the results proved that Bifidobacterium could be a potential probiotic for alleviating diarrhea from ETEC infection.

Non-Digestible Oligosaccharides and Short Chain Fatty Acids as Therapeutic Targets against Enterotoxin-Producing Bacteria and Their Toxins

Enterotoxin-producing bacteria (EPB) have developed multiple mechanisms to disrupt gut homeostasis, and provoke various pathologies. A major part of bacterial cytotoxicity is attributed to the secretion of virulence factors, including enterotoxins. Depending on their structure and mode of action, enterotoxins intrude the intestinal epithelium causing long-term consequences such as hemorrhagic colitis. Multiple non-digestible oligosaccharides (NDOs), and short chain fatty acids (SCFA), as their metabolites produced by the gut microbiota, interact with enteropathogens and their toxins, which may result in the inhibition of the bacterial pathogenicity. NDOs characterized by diverse structural characteristics, block the pathogenicity of EPB either directly, by inhibiting bacterial adherence and growth, or biofilm formation or indirectly, by promoting gut microbiota. Apart from these abilities, NDOs and SCFA can interact with enterotoxins and reduce their cytotoxicity. These anti-virulent effects mostly rely on their ability to mimic the structure of toxin receptors and thus inhibiting toxin adherence to host cells. This review focuses on the strategies of EPB and related enterotoxins to impair host cell immunity, discusses the anti-pathogenic properties of NDOs and SCFA on EPB functions and provides insight into the potential use of NDOs and SCFA as effective agents to fight against enterotoxins.

Effects of Probiotics Administration on Human Metabolic Phenotype

The establishment of the beneficial interactions between the host and its microbiota is essential for the correct functioning of the organism, since microflora alterations can lead to many diseases. Probiotics improve balanced microbial communities, exerting substantial health-promoting effects. Here we monitored the molecular outcomes, obtained by gut microflora modulation through probiotic treatment, on human urine and serum metabolic profiles, with a metabolomic approach. Twenty-two subjects were enrolled in the study and administered with two different probiotic types, both singularly and in combination, for 8 weeks. Urine and serum samples were collected before and during the supplementation and were analyzed by nuclear magnetic resonance (NMR) spectroscopy and statistical analyses. After eight weeks of treatment, probiotics deeply influence the urinary metabolic profiles of the volunteers, without significantly altering their single phenotypes. Anyway, bacteria supplementation tends to reduce the differences in metabolic phenotypes among individuals. Overall, the effects are recipient-dependent, and in some individuals, robust effects are already well visible after four weeks. Modifications in metabolite levels, attributable to each type of probiotic administration, were also monitored. Metabolomic analysis of biofluids turns out to be a powerful technique to monitor the dynamic interactions between the microflora and the host, and the individual response to probiotic assumption.

Experimental Inoculation of Coral Recruits With Marine Bacteria Indicates Scope for Microbiome Manipulation in Acropora tenuis and Platygyra daedalea

Coral-associated microorganisms are essential for maintaining the health of the coral holobiont by participating in nutrient cycling and protecting the coral host from pathogens. Under stressful conditions, disruption of the coral prokaryotic microbiome is linked to increased susceptibility to diseases and mortality. Inoculation of corals with beneficial microbes could confer enhanced stress tolerance to the host and may be a powerful tool to help corals thrive under challenging environmental conditions. Here, we explored the feasibility of coral early life stage microbiome manipulation by repeatedly inoculating coral recruits with a bacterial cocktail generated in the laboratory. Co-culturing the two species Acropora tenuis and Platygyra daedalea allowed us to simultaneously investigate the effect of host factors on the coral microbiome. Inoculation cocktails were regularly prepared from freshly grown pure bacterial cultures, which were hence assumed viable, and characterized via the optical density measurement of each individual strain put in suspension. Coral early recruits were inoculated seven times over 3 weeks and sampled once 36 h following the last inoculation event. At this time point, the cumulative inoculations with the bacterial cocktails had a strong effect on the bacterial community composition in recruits of both coral species. While the location of bacterial cells within the coral hosts was not assessed, metabarcoding using the 16S rRNA gene revealed that two and six of the seven bacterial strains administered through the cocktails were significantly enriched in inoculated recruits of A. tenuis and P. daedalea, respectively, compared to control recruits. Despite being reared in the same environment, A. tenuis and P. daedalea established significantly different bacterial communities, both in terms of taxonomic composition and diversity measurements. These findings indicate that coral host factors as well as the environmental bacterial pool play a role in shaping coral-associated bacterial community composition. Host factors may include microbe transmission mode (horizontal versus maternal) and host specificity. While the long-term stability of taxa included in the bacterial inocula as members of the host-associated microbiome remains to be evaluated, our results provide support for the feasibility of coral microbiome manipulation, at least in a laboratory setting.

Gut microbiota and its mysteries

Gut microbiota are microorganisms that inhabit the gut; they coexist peacefully with the host, thereby contributing to the health and well-being of individuals. Bacteroidetes and Firmicutes largely dominate the gut microbial flora. The intestinal flora promotes intestinal mucosal integrity, provides essential nutrients such as vitamins and enzymes, protects the body against pathogens and produces antimicrobial peptides such as defensins, C-type lectins, cathelicidins, they also play an active role in the innate and adaptive immune system. Gut microbial flora plays an active role in the synthesis of short-chain fatty acids such as butyrate, propionate and acetate. Gut microbiota also plays a significant role in the cognitive and behavioural functions of the host. A balanced gut microbiota shifts to dysbiosis, due to intake of high fat or sugar or other factors like sedentary lifestyle. The dysbiosis of the gut results in increased permeability, endotoxaemic, insulin resistant, systemic inflammation, adiposity and metabolic disorders such as type 2 diabetes mellitus, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, irritable bowel disorder, colorectal cancer, etc. A prudent lifestyle modification, added on with use of probiotics and prebiotic restore the normal flora of the gut, especially in patients with Clostridium difficle-associated diarrhoea, inflammatory bowel syndrome, liver disease and colon cancer. Faecal microbial transplant is an important therapeutic tool in many illness related with the gut. Thereby, understanding the gut microbial signatures in various diseases yields various novel therapeutic targets. Human gut microbiota has a prognostic, diagnostic and therapeutic potential which is recognised worldwide.

Exercise influence on the microbiome-gut-brain axis

The microbiome in the gut is a diverse environment, housing the majority of our bacterial microbes. This microecosystem has a symbiotic relationship with the surrounding multicellular organism, and a balance and diversity of specific phyla of bacteria support general health. When gut bacteria diversity diminishes, there are systemic consequences, such as gastrointestinal and psychological distress. This pathway of communication is known as the microbiome-gut-brain axis. Interventions such as probiotic supplementation that influence microbiome also improve both gut and brain disorders. Recent evidence suggests that aerobic exercise improves the diversity and abundance of genera from the Firmcutes phylum, which may be the link between the positive effects of exercise on the gut and brain. The purpose of this review is to explain the complex communication pathway of the microbiome-gut-brain axis and further examine the role of exercise on influencing this communication highway.

Microbiota of Chronic Diabetic Wounds: Ecology, Impact, and Potential for Innovative Treatment Strategies

World Health Organization considered diabetes as one of the 20th century epidemics, estimating that over 10% of the world population is diabetic or at high risk. Self-assessment studies indicate that diabetic patients consider chronic wounds to affect their quality of life more dramatically than vision loss or renal failure. In addition to being the main reason for diabetic patients' hospitalization, the economic burden of diabetic chronic wounds is close to 1% of United Kingdom and United States health systems budgets, which exceeds the funds allocated to the treatment of some types of cancer in both countries. Among the factors preceding the emergence of chronic diabetic wounds, also designated diabetic foot ulcers (DFUs), hygiene and pressure in specific areas are under patient control, while others are still far from being understood. A triple impairment in the innervation, immune responses, and vascularization associated to DFU has been extensively studied by the scientific community. However, the skin natural microbiota has only recently emerged as having a tremendous impact on DFU emergence and evolution to chronicity. Despite the great inter- and intra-variability of microbial colonizers, ongoing efforts are now focused on deciphering the impact of commensal and pathogenic microbiota on DFU etiology, as well as the mechanisms of interkingdom microbial-host communication. This review summarizes recent work in this context and offers new microbiological perspectives that may hold potential in the prevention and treatment of chronic diabetic wounds.

Proteomic characterization and bio-informatic analysis of differentially expressed E. coli Nissle 1917 proteins with response to cocoti wine stress

The present study emphases the comparative proteomic analysis of Escherichia coli Nissle 1917 under cocoti palm wine stress and identified differentially expressed proteins. Protein samples were analyzed by 2-D, MALDI-TOF combined with MS access. In 2-D electrophoresis, eight differentially expressed proteins were identified: five up-regulated, two down-regulated and one newly expressed protein. Protein spots were digested with trypsin for MALDI-TOF-MS analysis; protein sequences were obtained from MASCOT search. Sequences were aligned with template using Swiss Model server. Phyre-2 was used to predict homology modeling, RasMol was used to analyze the modeling structures, PSVS server was utilized to validate the protein structure by Ramachandran's plot analysis, physical and chemical properties were analyzed using ProtParam server, Phylogenetic tree was constructed by Mega4. UniProt search helps to find protein functional information of differentially expressed proteins, involved in catalytic activities, regulation mechanisms, DNA damage stimulus, anti-termination and termination process, protein binding, electron transport mechanism, and cell signaling process functions. A detailed exploration of the proteins under cocoti palm wine stress have provided the composition, structure and functions of the expressed proteins for further investigation.

Assessing the Risk of Probiotic Dietary Supplements in the Context of Antibiotic Resistance

Probiotic bacteria are known to harbor intrinsic and mobile genetic elements that confer resistance to a wide variety of antibiotics. Their high amounts in dietary supplements can establish a reservoir of antibiotic resistant genes in the human gut. These resistant genes can be transferred to pathogens that share the same intestinal habitat thus resulting in serious clinical ramifications. While antibiotic resistance of probiotic bacteria from food, human and animal sources have been well-documented, the resistant profiles of probiotics from dietary supplements have only been recently studied. These products are consumed with increasing regularity due to their health claims that include the improvement of intestinal health and immune response as well as prevention of acute and antibiotic-associated diarrhea and cancer; but, a comprehensive risk assessment on the spread of resistant genes to human health is lacking. Here, we highlight recent reports of antibiotic resistance of probiotic bacteria isolated from dietary supplements, and propose complementary strategies that can shed light on the risks of consuming such products in the context of a global widespread of antibiotic resistance. In concomitant with a broader screening of antibiotic resistance in probiotic supplements is the use of computational simulations, live imaging and functional genomics to harvest knowledge on the evolutionary behavior, adaptations and dynamics of probiotics studied in conditions that best represent the human gut including in the presence of antibiotics. The underlying goal is to enable the health benefits of probiotics to be exploited in a responsible manner and with minimal risk to human health.

Anaerobes as Sources of Bioactive Compounds and Health Promoting Tools

Aerobic microorganisms have been sources of medicinal agents for several decades and an impressive variety of drugs have been isolated from their cultures, studied and formulated to treat or prevent diseases. On the other hand, anaerobes, which are believed to be the oldest life forms on earth and evolved remarkably diverse physiological functions, have largely been neglected as sources of bioactive compounds. However, results obtained from the limited research done so far show that anaerobes are capable of producing a range of interesting bioactive compounds that can promote human health. In fact, some of these bioactive compounds are found to be novel in their structure and/or mode of action.Anaerobes play health-promoting roles through their bioactive products as well as application of whole cells. The bioactive compounds produced by these microorganisms include antimicrobial agents and substances such as immunomodulators and vitamins. Bacteriocins produced by anaerobes have been in use as preservatives for about 40 years. Because these substances are effective at low concentrations, encounter relatively less resistance from bacteria and are safe to use, there is a growing interest in these antimicrobial agents. Moreover, several antibiotics have been reported from the cultures of anaerobes. Closthioamide and andrimid produced by Clostridium cellulolyticum and Pantoea agglomerans, respectively, are examples of novel antibiotics of anaerobe origin. The discovery of such novel bioactive compounds is expected to encourage further studies which can potentially lead to tapping of the antibiotic production potential of this fascinating group of microorganisms.Anaerobes are widely used in preparation of fermented foods and beverages. During the fermentation processes, these organisms produce a number of bioactive compounds including anticancer, antihypertensive and antioxidant substances. The well-known health promoting effect of fermented food is mostly due to these bioactive compounds. In addition to their products, whole cell anaerobes have very interesting applications for enhancing the quality of life. Probiotic anaerobes have been on the market for many years and are receiving growing acceptance as health promoters. Gut anaerobes have been used to treat patients suffering from severe Clostridium difficile infection syndromes including diarrhoea and colitis which cannot be treated by other means. Whole cell anaerobes are also studied to detect and cure cancer. In recent years, evidence is emerging that anaerobes constituting the microbiome are linked to our overall health. A dysfunctional microbiome is believed to be the cause of many diseases including cancer, allergy, infection, obesity, diabetes and several other disorders. Maintaining normal microflora is believed to alleviate some of these serious health problems. Indeed, the use of probiotics and prebiotics which favourably change the number and composition of the gut microflora is known to render a health promoting effect. Our interaction with the microbiome anaerobes is complex. In fact, not only our lives but also our identities are more closely linked to the anaerobic microbial world than we may possibly imagine. We are just at the beginning of unravelling the secret of association between the microbiome and human body, and a clear understanding of the association may bring a paradigm shift in the way we diagnose and treat diseases and disorders. This chapter highlights some of the work done on bioactive compounds and whole cell applications of the anaerobes that foster human health and improve the quality of life.

Promotility Action of the Probiotic Bifidobacterium lactis HN019 Extract Compared with Prucalopride in Isolated Rat Large Intestine

Attention is increasingly being focussed on probiotics as potential agents to restore or improve gastrointestinal (GI) transit. Determining mechanism of action would support robust health claims. The probiotic bacterium Bifidobacterium lactis HN019 reduces transit time, but its mechanisms of action and effects on motility patterns are poorly understood. The aim of this study was to investigate changes in GI motility induced by an extract of HN019 on distinct patterns of colonic motility in isolated rat large intestine, compared with a known promotility modulator, prucalopride. The large intestines from male Sprague Dawley rats (3–6 months) were perfused with Kreb's buffer at 37°C in an oxygenated tissue bath. Isometric force transducers recorded changes in circular muscle activity at four independent locations assessing contractile propagation between the proximal colon and the rectum. HN019 extract was perfused through the tissue bath and differences in tension and frequency quantified relative to pre-treatment controls. Prucalopride (1 μM) increased the frequency of propagating contractions (by 75 ± 26%) in the majority of preparations studied (10/12), concurrently decreasing the frequency of non-propagating contractions (by 50 ± 11%). HN019 extract had no effect on contractile activity during exposure (n = 8). However, following wash out, contraction amplitude of propagating contractions increased (by 55 ± 18%) in the distal colon, while the frequency of non-propagating proximal contractions decreased by 57 ± 7%. The prokinetic action of prucalopride increased the frequency of synchronous contractions along the length of colon, likely explaining increased colonic rate of transit in vivo. HN019 extract modified motility patterns in a different manner by promoting propagating contractile amplitude and inhibiting non-propagations, also demonstrating prokinetic activity consistent with the reduction of constipation by B. lactis HN019 in humans.

Selection of a candidate probiotic strain of Pediococcus pentosaceus from the faecal microbiota of horses by in vitro testing and health claims in a mouse model of Salmonella infection

AIMS

The aim of this study was to verify the suitable use of candidate 'probiotics' selected by in vitro tests and the importance of in vivo assays to nominate micro-organisms as probiotics and alternative prophylactic treatments for Salmonella Typhimurium infection.

METHODS AND RESULTS

Thirty-three lactic acid bacteria (LAB) isolated from foal's faeces were assessed based on the main desirable functional in vitro criteria. Based on these results, Pediococcus pentosaceus strain 40 was chosen to evaluate its putative probiotic features in a mouse model of Salmonella infection. Daily intragastric doses of Ped. pentosaceus 40 for 10 days before and 10 days after Salmonella challenge (10⁶ CFU of Salm. Typhimurium per mouse) led to a significant aggravation in mouse health by increasing weight loss, worsening clinical symptoms and anticipating the time and the number of deaths by Salmonella. Pediococcus pentosaceus modulated cell-mediated immune responses by up-regulation of the gene expression of the proinflammatory cytokines IFN-γ and TNF-α in the small intestine.

CONCLUSION

The usual criteria were used for in vitro screening of a large number of LAB for desirable probiotic functional properties. However, the best candidate probiotic strain identified, Ped. pentosaceus #40, aggravated the experimental disease in mice.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings emphasize the need for prophylactic or therapeutic effectiveness to be demonstrated in in vivo models to make precise health claims.

THE INTESTINAL MICROBIOTA AND THE ROLE OF PROBIOTICS IN IRRITABLE BOWEL SYNDROME: a review

Irritable bowel syndrome is a common, chronic relapsing gastrointestinal disorder that affects 7%-22% of the population worldwide. According to Rome III Criteria, the disorder is defined by the coexistence of abdominal discomfort or pain associated with an alteration in bowel habits. Its pathophysiology is not completely understood but, in addition to some important abnormalities, the disturbed intestinal microbiota has also been described supported by several strands of evidence. The treatment of irritable bowel syndrome is based upon several therapeutic approaches but few have been successful or without adverse events and more recently the gut microbiota and the use of probiotics have emerged as a factor to be considered. Probiotics are live micro-organisms which when consumed in adequate amounts confer a health benefit to the host, such as Lactic bacteria among others. An important scientific rationale has emerged for the use of probiotics in irritable bowel syndrome, although the data regarding different species are still limited. Not all probiotics are beneficial: it is important to select the specific strain which should be supported by good evidence base. The mechanisms of action of probiotics are described and the main strains are quoted.

Protective effects of Lactobacillus plantarum on epithelial barrier disruption caused by enterotoxigenic Escherichia coli in intestinal porcine epithelial cells

Tight junctions (TJs) play an important role in maintaining the mucosal barrier function and gastrointestinal health of animals. Lactobacillus plantarum (L. plantarum) was reported to protect the intestinal barrier function of early-weaned piglets against enterotoxigenic Escherichia coli (ETEC) K88 challenge; however, the underlying cellular mechanism of this protection was unclear. Here, an established intestinal porcine epithelia cell (IPEC-J2) model was used to investigate the protective effects and related mechanisms of L. plantarum on epithelial barrier damages induced by ETEC K88. Epithelial permeability, expression of inflammatory cytokines, and abundance of TJ proteins, were determined. Pre-treatment with L. plantarum for 6h prevented the reduction in transepithelial electrical resistance (TEER) (P<0.05), inhibited the increased transcript abundances of interleukin-8 (IL-8) and tumor necrosis factor (TNF-α) (P<0.05), decreased expression of claudin-1, occludin and zonula occludens (ZO-1) (P<0.05) and protein expression of occludin (P<0.05) of IPEC-J2 cells caused by ETEC K88. Moreover, the mRNA expression of negative regulators of toll-like receptors (TLRs) [single Ig Il-1-related receptor (SIGIRR), B-cell CLL/lymphoma 3 (Bcl3), and mitogen-activated protein kinase phosphatase-1 (MKP-1)] in IPEC-J2 cells pre-treated with L. plantarum were higher (P<0.05) compared with those in cells just exposed to K88. Furthermore, L. plantarum was shown to regulate proteins of nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. These results indicated that L. plantarum may improve epithelial barrier function by maintenance of TEER, inhibiting the reduction of TJ proteins, and reducing the expression of proinflammatory cytokines induced by ETEC K88, possibly through modulation of TLRs, NF-κB and MAPK pathways.

Lactobacillus plantarum NCU116 Attenuates Cyclophosphamide-Induced Immunosuppression and Regulates Th17/Treg Cell Immune Responses in Mice

The balance of T helper cells 17 (Th17)/regulatory T cells (Treg) plays a key role in maintaining a normal immune response. It is well-known that cyclophosphamide (CTX) applied at high dose often damages the immune system by inhibiting immune cell proliferation. In this study, the immunomodulating effects of Lactobacillus plantarum NCU116 in CTX-induced immunosuppression mice were investigated. Results showed that the levels of cytokines interleukin (IL)-17 and IL-21 were significantly increased after 10 days of treatment with a high dose of NCU116 (46.92 ± 4.28 and 119.92 ± 10.89, respectively) compared with the model group (36.20 ± 2.63, 61.00 ± 6.92, respectively), and the levels of cytokines IL-23 and TGF-β3 of the three NCU116 treatment groups were significantly higher than that of the model group (90.48 ± 6.33 and 140.45 ± 14.30, respectively) (p < 0.05) and close to 62 and 69% of the normal group's level (140.98 ± 14.74 and 266.95 ± 23.11, respectively) at 10 days. The bacterium was also found to increase the expression levels of Th17 immune response and Treg immune response specific transcription factors RORγt and Foxp3. In addition, the bacterium significantly increased the number of CD4(+)T cells and dendrtic cells (DCs) and up-regulated mRNA expression of Toll-like receptors (TLRs). These findings demonstrated that NCU116 has the potential ability to enhance intestinal mucosa immunity and regulate the Th17/Treg balance, which may be attributed to the TLR pathway in DCs.

Use of probiotics in prevention and treatment of patients with Clostridium difficile infection

Clostridium difficile is an anaerobic, gram positive, sporulating, toxin-producing bacillus which causes a spectrum of clinical disease ranging from an asymptomatic carrier state to toxic megacolon and fulminant disease. Infection with C. difficile is an expensive and pervasive health care burden. The current theory regarding the development of C. difficile infection (CDI) suggests that disruption of the structure and/or function of an individual's normal intestinal microbiota enables colonization by C. difficile, and in the absence of an effective immune response, the bacteria causes illness. In this article we discuss the role of the colonic microbiota in the development of CDI and the potential role of probiotics in preventing and treating CDI. We review the evidence from in vitro laboratory and pre-clinical studies, as well as evidence from clinical studies and discuss the current recommendations for the use of probiotics for CDI in clinical practice.

Nutritional Keys for Intestinal Barrier Modulation

The intestinal tract represents the largest interface between the external environment and the human body. Nutrient uptake mostly happens in the intestinal tract, where the epithelial surface is constantly exposed to dietary antigens. Since inflammatory response toward these antigens may be deleterious for the host, a plethora of protective mechanisms take place to avoid or attenuate local damage. For instance, the intestinal barrier is able to elicit a dynamic response that either promotes or impairs luminal antigens adhesion and crossing. Regulation of intestinal barrier is crucial to control intestinal permeability whose increase is associated with chronic inflammatory conditions. The cross talk among bacteria, immune, and dietary factors is able to modulate the mucosal barrier function, as well as the intestinal permeability. Several nutritional products have recently been proposed as regulators of the epithelial barrier, even if their effects are in part contradictory. At the same time, the metabolic function of the microbiota generates new products with different effects based on the dietary content. Besides conventional treatments, novel therapies based on complementary nutrients are now growing. Fecal therapy has been recently used for the clinical treatment of refractory Clostridium difficile infection instead of the classical antibiotic therapy. In the present review, we will outline the epithelial response to nutritional components derived from dietary intake and microbial fermentation focusing on the consequent effects on the integrity of the epithelial barrier.

Escherichia coli Nissle 1917 enhances bioavailability of serotonin in gut tissues through modulation of synthesis and clearance

Accumulating evidence shows indigenous gut microbes can interact with the human host through modulation of serotonin (5-HT) signaling. Here we investigate the impact of the probiotic Escherichia coli Nissle 1917 (EcN) on 5-HT signalling in gut tissues. Ex-vivo mouse ileal tissue sections were treated with either EcN or the human gut commensal MG1655, and effects on levels of 5-HT, precursors, and metabolites, were evaluated using amperometry and high performance liquid chromatography with electrochemical detection (HPLC-EC). Exposure of tissue to EcN cells, but not MG1655 cells, was found to increase levels of extra-cellular 5-HT. These effects were not observed when tissues were treated with cell-free supernatant from bacterial cultures. In contrast, when supernatant recovered from untreated ileal tissue was pre-incubated with EcN, the derivative cell-free supernatant was able to elevate 5-HT overflow when used to treat fresh ileal tissue. Measurement of 5-HT precursors and metabolites indicated EcN also increases intracellular 5-HTP and reduces 5-HIAA. The former pointed to modulation of tryptophan hydroxylase-1 to enhance 5-HT synthesis, while the latter indicates an impact on clearance into enterocytes through SERT. Taken together, these findings show EcN is able to enhance 5-HT bioavailability in ileal tissues through interaction with compounds secreted from host tissues.

Effects of Lactobacillus johnsonii and Lactobacillus reuteri on gut barrier function and heat shock proteins in intestinal porcine epithelial cells

Heat shock proteins (HSPs) are a set of highly conserved proteins that can serve as intestinal gate keepers in gut homeostasis. Here, effects of a probiotic, Lactobacillus rhamnosus GG (LGG), and two novel porcine isolates, Lactobacillus johnsonii strain P47-HY and Lactobacillus reuteri strain P43-HUV, on cytoprotective HSP expression and gut barrier function, were investigated in a porcine IPEC-J2 intestinal epithelial cell line model. The IPEC-J2 cells polarized on a permeable filter exhibited villus-like cell phenotype with development of apical microvilli. Western blot analysis detected HSP expression in IPEC-J2 and revealed that L. johnsonii and L. reuteri strains were able to significantly induce HSP27, despite high basal expression in IPEC-J2, whereas LGG did not. For HSP72, only the supernatant of L. reuteri induced the expression, which was comparable to the heat shock treatment, which indicated that HSP72 expression was more stimulus specific. The protective effect of lactobacilli was further studied in IPEC-J2 under an enterotoxigenic Escherichia coli (ETEC) challenge. ETEC caused intestinal barrier destruction, as reflected by loss of cell–cell contact, reduced IPEC-J2 cell viability and transepithelial electrical resistance, and disruption of tight junction protein zonula occludens-1. In contrast, the L. reuteri treatment substantially counteracted these detrimental effects and preserved the barrier function. L. johnsonii and LGG also achieved barrier protection, partly by directly inhibiting ETEC attachment. Together, the results indicate that specific strains of Lactobacillus can enhance gut barrier function through cytoprotective HSP induction and fortify the cell protection against ETEC challenge through tight junction protein modulation and direct interaction with pathogens.

Disruption of Escherichia coli Nissle 1917 K5 capsule biosynthesis, through loss of distinct kfi genes, modulates interaction with intestinal epithelial cells and impact on cell health

Escherichia coli Nissle 1917 (EcN) is among the best characterised probiotics, with a proven clinical impact in a range of conditions. Despite this, the mechanisms underlying these "probiotic effects" are not clearly defined. Here we applied random transposon mutagenesis to identify genes relevant to the interaction of EcN with intestinal epithelial cells. This demonstrated mutants disrupted in the kfiB gene, of the K5 capsule biosynthesis cluster, to be significantly enhanced in attachment to Caco-2 cells. However, this phenotype was distinct from that previously reported for EcN K5 deficient mutants (kfiC null mutants), prompting us to explore further the role of kfiB in EcN:Caco-2 interaction. Isogenic mutants with deletions in kfiB (EcNΔkfiB), or the more extensively characterised K5 capsule biosynthesis gene kfiC (EcNΔkfiC), were both shown to be capsule deficient, but displayed divergent phenotypes with regard to impact on Caco-2 cells. Compared with EcNΔkfiC and the EcN wild-type, EcNΔkfiB exhibited significantly greater attachment to Caco-2 cells, as well as apoptotic and cytotoxic effects. In contrast, EcNΔkfiC was comparable to the wild-type in these assays, but was shown to induce significantly greater COX-2 expression in Caco-2 cells. Distinct differences were also apparent in the pervading cell morphology and cellular aggregation between mutants. Overall, these observations reinforce the importance of the EcN K5 capsule in host-EcN interactions, but demonstrate that loss of distinct genes in the K5 pathway can modulate the impact of EcN on epithelial cell health.

Probiotics in dietary guidelines and clinical recommendations outside the European Union

Fermented foods have been consumed for centuries across many geographical locales and have traditionally been considered healthy foods, partly because of the live microbes contained in them. The concept of “probiotics” further requires that the microbes be defined and their health effects be demonstrated through human intervention studies or other suitable investigations before marketing with corresponding health messages. Here, we review recommendations for fermented foods and probiotics in several countries outside the EU, focusing on food-based dietary guidelines. We emphasize recommendations on yoghurt and probiotics made by expert bodies. We found that dietary guidelines commonly advocate the consumption of yoghurt or similar products, but specific comments on probiotics are rare. Further, we reviewed guidelines from clinical associations. In general, they acknowledge the beneficial effects of probiotics, but often suggest the need for further research. This is true despite good quality evidence supporting the role of probiotics for certain health effects, such as prevention of eczema in infants, management of side effects from antibiotics and alleviation of functional bowel symptoms. Additional research to support future dietary recommendations should focus on determining effect size, identifying responders and non-responders, clarifying strain-specificity of effects and confirming mechanisms.

The probiotic Escherichia coli Nissle 1917 inhibits propagating colonic contractions in the rat isolated large intestine

The objective of this research was to test an in vitro motility model by investigating whether a probiotic that reduces diarrhea in humans would reduce motility in the rat colon in vitro. The probiotic Escherichia coli Nissle 1917 (EcN) the active ingredient in Mutaflor® was used as an example probiotic because it is effective for treating infectious diarrheal diseases. The effect of EcN on motility was compared in two colonic preparations. In distal colon segments EcN extract decreased the tension of spontaneous contractions by 74% and frequency by 46% compared with pre-treatment controls. In the whole large intestine the number of synchronized spontaneous propagating contractions decreased by 86% when EcN extract was applied externally and 69% when applied via the lumen compared with pre-treatment. From the inhibition produced by EcN extract in the distal colon segment a myogenic action was inferred and in the whole large intestine neural involvement was implicated. Both are consistent with its anti-diarrheal effect in humans.

Expression of heat shock proteins 27 and 72 correlates with specific commensal microbes in different regions of porcine gastrointestinal tract

The gastrointestinal (GI) tract of mammals is inhabited by trillions of microorganisms, resulting in exceedingly complex networking. The interaction between distinct bacterial species and the host immune system is essential in maintaining homeostasis in the gut ecosystem. For instance, the gut commensal microbiota dictates intestinal mucosa maturation and its abundant immune components, such as cytoprotective heat shock proteins (HSP). Here we examined physiological expression of HSP in the normal porcine GI tract and found it to be gut region- and cell type-specific in response to dietary components, microbes, and microbial metabolites to which the mucosa surface is exposed. Correlations between HSP72 expression and ileal Lactobacillus spp. and colonic clostridia species, and between HSP27 expression and uronic acid ingestion, were important interplays identified here. Thus this study provides novel insights into host-microbe interactions shaping the immune system that are modifiable by dietary regime.

Microbiota and metabolome associated with immunoglobulin A nephropathy (IgAN)

This study aimed at investigating the fecal microbiota, and the fecal and urinary metabolome of non progressor (NP) and progressor (P) patients with immunoglobulin A nephropathy (IgAN). Three groups of volunteers were included in the study: (i) sixteen IgAN NP patients; (ii) sixteen IgAN P patients; and (iii) sixteen healthy control (HC) subjects, without known diseases. Selective media were used to determine the main cultivable bacterial groups. Bacterial tag-encoded FLX-titanium amplicon pyrosequencing of the 16S rDNA and 16S rRNA was carried out to determine total and metabolically active bacteria, respectively. Biochrom 30 series amino acid analyzer and gas-chromatography mass spectrometry/solid-phase microextraction (GC-MS/SPME) analyses were mainly carried out for metabolomic analyses. As estimated by rarefaction, Chao and Shannon diversity index, the lowest microbial diversity was found in P patients. Firmicutes increased in the fecal samples of NP and, especially, P patients due to the higher percentages of some genera/species of Ruminococcaceae, Lachnospiraceae, Eubacteriaceae and Streptococcaeae. With a few exceptions, species of Clostridium, Enterococcus and Lactobacillus genera were found at the highest levels in HC. Bacteroidaceae, Porphyromonadaceae, Prevotellaceae and Rikenellaceae families differed among NP, P and HC subjects. Sutterellaceae and Enterobacteriaceae species were almost the highest in the fecal samples of NP and/or P patients. Compared to HC subjects, Bifidobacterium species decreased in the fecal samples of NP and P. As shown by multivariate statistical analyses, the levels of metabolites (free amino acids and organic volatile compounds) from fecal and urinary samples markedly differentiated NP and, especially, P patients.

Bifidobacterium breve attenuates murine dextran sodium sulfate-induced colitis and increases regulatory T cell responses

While some probiotics have shown beneficial effects on preventing or treating colitis development, others have shown no effects. In this study, we have assessed the immunomodulating effects of two probiotic strains, Lactobacillus rhamnosus (L. rhamnosus) and Bifidobacterium breve (B. breve) on T cell polarization in vitro, using human peripheral blood mononuclear cells (PBMC), and in vivo, using murine dextran sodium sulfate (DSS) colitis model. With respect to the latter, the mRNA expression of T cell subset-associated transcription factors and cytokines in the colon was measured and the T helper type (Th) 17 and regulatory T cell (Treg) subsets were determined in the Peyer's patches. Both L. rhamnosus and B. breve incubations in vitro reduced Th17 and increased Th2 cell subsets in human PBMCs. In addition, B. breve incubation was also able to reduce Th1 and increase Treg cell subsets in contrast to L. rhamnosus. In vivo intervention with B. breve, but not L. rhamnosus, significantly attenuated the severity of DSS-induced colitis. In DSS-treated C57BL/6 mice, intervention with B. breve increased the expression of mRNA encoding for Th2- and Treg-associated cytokines in the distal colon. In addition, intervention with B. breve led to increases of Treg and decreases of Th17 cell subsets in Peyer's patches of DSS-treated mice. B. breve modulates T cell polarization towards Th2 and Treg cell-associated responses in vitro and in vivo. In vivo B. breve intervention ameliorates DSS-induced colitis symptoms and this protective effect may mediated by its effects on the T-cell composition.

Fecal microbiota transplantation: from the 4th century to 2013

Intestinal microbiota has been defined as a dynamic human organ. Many diseases occur as a result of the disorder of intestinal microbiota. Human fecal microbiota transplantation (FMT), which was originally reported in China in the 4^th century, has become popular in recent years, since it shows an amazing effect in the treatment of pseudomembranous colitis and recurrent Clostridium difficile infection (CDI). It has not only been proposed as a first-line treatment for recurrent CDI but also been utilized to treat inflammatory bowel disease, irritable bowel syndrome, metabolic syndrome, and chronic fatigue syndrome. The mechanism behind the therapeutic effects of FMT is still unclear. The most widely accepted hypothesis is that FMT can use the whole intestinal microbiota from a healthy donor to replace the patient's disordered gut microbiota. At present, FMT is still in the beginning stage, and there is an urgent need to develop standardized protocols and to conduct safety analysis. This review tries to present the past, present and future of FMT by introducing the relationship between gut flora and diseases and the utilization of FMT.

A randomized double-blind controlled trial: impact of probiotics on diarrhea in patients treated with pelvic radiation

BACKGROUND & AIMS

Radical radiation therapy is commonly used for treatment of pelvic cancer. Up to 80% of patients receiving radiotherapy will develop acute radiation induced diarrhea. The primary aim of this randomized double blind controlled trial is to evaluate the effect of the probiotic Bifilact(®) on moderate and severe treatment-induced diarrhea during pelvic radiation.

METHODS

Patients with pelvic cancers were treated between 2006 and 2010 at L'Hôtel-Dieu de Québec, University Health Center. Some patients had surgery before pelvic radiotherapy and some received chemotherapy. A total of 246 Patients were randomized between a placebo and either of two regiments of double strain Bifilact(®) probiotics (Lactobacillus acidophilus LAC-361 and Bifidobacterium longum BB-536): a standard dose twice a day (1.3 billion CFU) or a high dose three times a day (10 billion CFU). Patients were trained to record their digestive symptoms daily with a standardized scale and they met a registered dietician and radiation oncologist every week during treatment. The main analysis compared time to first appearance of grade ≥2-3-4 diarrhea using Kaplan-Meier curves as measured by proportion of patients without moderate and severe diarrhea.

RESULTS

229 patients were analyzed. The difference between the groups for overall grade 2-3-4 diarrhea was not statistically significant (p = 0.13). However at 60 days, the proportion of patients without moderate and severe diarrhea in the standard dose group (35%) was more than twice as high as that of the placebo group (17%) with a hazard ratio of 0.69 (p = 0.04). In patients who had surgery, the standard probiotics dose group had a better proportion of patients without very severe diarrhea than the placebo group, respectively 97% and 74% (p = 0.03). In all groups, the average number of bowel movements per day during treatment was less than 3 soft stools (p = 0.80) and the median abdominal pain less than 1 based on the National Cancer Institute scale (p = 0.23).

CONCLUSION

Standard dose of Bifilact(®) may reduce radiation induced grade 2-3-4 diarrhea at the end of the treatment of patients with pelvic cancer. In patients operated on before RT, a standard dose of probiotics may reduce radiation induced grade 4 diarrhea. Nutritional interventions by a registered dietician seemed to reduce global digestive symptoms.

TRIAL REGISTRATION

clinicaltrials.gov. Identifier NCT01839721.

Intestinal microbiota and immune function in the pathogenesis of irritable bowel syndrome

The pathophysiology of irritable bowel syndrome (IBS) is believed to involve alterations in the brain-gut axis; however, the etiological triggers and mechanisms by which these changes lead to symptoms of IBS remain poorly understood. Although IBS is often considered a condition without an identified "organic" etiology, emerging evidence suggests that alterations in the gastrointestinal microbiota and altered immune function may play a role in the pathogenesis of the disorder. These recent data suggest a plausible model in which changes in the intestinal microbiota and activation of the enteric immune system may impinge upon the brain-gut axis, causing the alterations in gastrointestinal function and the clinical symptoms observed in patients with IBS. This review summarizes the current evidence for altered intestinal microbiota and immune function in IBS. It discusses the potential etiological role of these factors, suggests an updated conceptual model for the pathogenesis of the disorder, and identifies areas for future research.

Fecal microbiota transplantation: past, present and future

PURPOSE OF REVIEW

Fecal microbiota transplantation (FMT) re-establishes a balanced intestinal flora with resultant cure of recurrent Clostridium difficile infection (RCDI). FMT has also been used to treat other gastrointestinal (GI) diseases including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and chronic constipation and a variety of non-GI disorders. The purpose of this review is to discuss the intestinal microbiota and FMT treatment of GI and non-GI diseases.

RECENT FINDINGS

It is known that an imbalanced intestinal microbiota predisposes to CDI, IBD and IBS. The complex role of intestinal microbiota to maintain health, however, is a newer concept that is being increasingly studied. The microbiome plays an important role in cellular immunity and energy metabolism and has been implicated in the pathogenesis of non-GI autoimmune diseases, chronic fatigue syndrome, obesity and even some neuropsychiatric disorders.

SUMMARY

FMT is a highly effective cure for RCDI, but increased knowledge of the intestinal microbiota in health maintenance, as well as controlled trials of FMT in a wide range of disorders are needed before FMT can be accepted and applied clinically.

The influence of diet on the gut microbiota

Diet is a major factor driving the composition and metabolism of the colonic microbiota. The amount, type and balance of the main dietary macronutrients (carbohydrates, proteins and fats) have a great impact on the large intestinal microbiota. The human colon contains a dense population of bacterial cells that outnumber host cells 10-fold. Bacteroidetes, Firmicutes and Actinobacteria are the three major phyla that inhabit the human large intestine and these bacteria possess a fascinating array of enzymes that can degrade complex dietary substrates. Certain colonic bacteria are able to metabolise a remarkable variety of substrates whilst other species carry out more specialised activities, including primary degradation of plant cell walls. Microbial metabolism of dietary carbohydrates results mainly in the formation of short chain fatty acids and gases. The major bacterial fermentation products are acetate, propionate and butyrate; and the production of these tends to lower the colonic pH. These weak acids influence the microbial composition and directly affect host health, with butyrate the preferred energy source for the colonocytes. Certain bacterial species in the colon survive by cross-feeding, using either the breakdown products of complex carbohydrate degradation or fermentation products such as lactic acid for growth. Microbial protein metabolism results in additional fermentation products, some of which are potentially harmful to host health. The current 'omic era promises rapid progress towards understanding how diet can be used to modulate the composition and metabolism of the gut microbiota, allowing researchers to provide informed advice, that should improve long-term health status.