Th17 Cell Induction by Adhesion of Microbes to Intestinal Epithelial Cells.

Intestinal Th17 cells are induced and accumulate in response to colonization with a subgroup of intestinal microbes such as segmented filamentous bacteria (SFB) and certain extracellular pathogens. Here, we show that adhesion of microbes to intestinal epithelial cells (ECs) is a critical cue for Th17 induction. Upon monocolonization of germ-free mice or rats with SFB indigenous to mice (M-SFB) or rats (R-SFB), M-SFB and R-SFB showed host-specific adhesion to small intestinal ECs, accompanied by host-specific induction of Th17 cells. Citrobacter rodentium and Escherichia coli O157 triggered similar Th17 responses, whereas adhesion-defective mutants of these microbes failed to do so. Moreover, a mixture of 20 bacterial strains, which were selected and isolated from fecal samples of a patient with ulcerative colitis on the basis of their ability to cause a robust induction of Th17 cells in the mouse colon, also exhibited EC-adhesive characteristics.

Innate lymphoid cells regulate intestinal epithelial cell glycosylation.

Fucosylation of intestinal epithelial cells, catalyzed by fucosyltransferase 2 (Fut2), is a major glycosylation mechanism of host-microbiota symbiosis. Commensal bacteria induce epithelial fucosylation, and epithelial fucose is used as a dietary carbohydrate by many of these bacteria. However, the molecular and cellular mechanisms that regulate the induction of epithelial fucosylation are unknown. Here, we show that type 3 innate lymphoid cells (ILC3) induced intestinal epithelial Fut2 expression and fucosylation in mice. This induction required the cytokines interleukin-22 and lymphotoxin in a commensal bacteria-dependent and -independent manner, respectively. Disruption of intestinal fucosylation led to increased susceptibility to infection by Salmonella typhimurium. Our data reveal a role for ILC3 in shaping the gut microenvironment through the regulation of epithelial glycosylation.

Probiotics promote rapid-turnover protein production by restoring gut flora in patients with alcoholic liver cirrhosis.

BACKGROUND AND AIMS: Accumulating evidence suggests that deterioration of the gut flora contributes to the pathogenesis of alcoholic liver cirrhosis (ALC). However, the ALC flora profile and its response to probiotic treatment have not been fully examined. This double-blind placebo-controlled study aimed to evaluate whether the probiotic beverage Yakult 400 (Y400), which contains Lactobacillus casei strain Shirota, improves liver function in ALC patients, and to analyze the precise gut flora profile by real-time quantitative PCR (qPCR). METHODS: A total of 37 hospitalized ALC patients were randomly allocated to Y400 (n = 18) and placebo (n = 19) groups. Y400 or placebo was served twice a day during the first half of the four-week study. Serum concentrations of rapid-turnover proteins (i.e., transthyretin and transferrin), hypersensitive C-reactive protein, and interleukin-6 were measured weekly. qPCR analysis of fecal bacteria was performed biweekly; stocked fecal samples from 46 healthy subjects were used as references. RESULTS: Serum transthyretin levels significantly increased in the Y400 group in week 3; similar-although statistically insignificant-increases were seen for transferrin and albumin. Levels of hypersensitive C-reactive protein, but not interleukin-6, significantly decreased in week 4. Before treatment, populations of obligate anerobic bacteria were significantly smaller and those of Enterobacteriaceae were larger in patients than in healthy subjects examined in a previous study. Y400 corrected this imbalance. CONCLUSIONS: This is the first report describing the unique gut flora of ALC patients. Y400 treatment normalized the gut flora and improved liver function. These promising findings warrant further investigation in larger, multicenter studies.

Complete genome sequences of rat and mouse segmented filamentous bacteria, a potent inducer of th17 cell differentiation.

Segmented filamentous bacteria (SFB) are noncultivable commensals inhabiting the gut of various vertebrate species and have been shown to induce Th17 cells in mice. We present the complete genome sequences of both rat and mouse SFB isolated from SFB-monocolonized hosts. The rat and mouse SFB genomes each harbor a single circular chromosome of 1.52 and 1.59 Mb encoding 1346 and 1420 protein-coding genes, respectively. The overall nucleotide identity between the two genomes is 86%, and the substitution rate was estimated to be similar to that of the free-living E. coli. SFB genomes encode typical genes for anaerobic fermentation and spore and flagella formation, but lack most of the amino acid biosynthesis enzymes, reminiscent of pathogenic Clostridia, exhibiting large dependency on the host. However, SFB lack most of the clostridial virulence-related genes. Comparative analysis with clostridial genomes suggested possible mechanisms for host responses and specific adaptations in the intestine.

Beneficial effects of probiotic bifidobacterium and galacto-oligosaccharide in patients with ulcerative colitis: a randomized controlled study.

BACKGROUND/AIM: In previous studies, we described the beneficial effects of bifidobacteria-fermented milk in patients with ulcerative colitis (UC). Here, we examined the effects of a live Bifidobacterium breve strain Yakult, a probiotic contained in bifidobacteria-fermented milk, and galacto-oligosaccharide (GOS) as synbiotics in UC patients. METHODS: Forty-one patients with mild to moderate UC were assigned to two groups; one group was treated with the synbiotics and the other was not (control). The treatment group ingested 1 g of the probiotic powder (10(9) CFU/g) three times a day, and 5.5 g of GOS once a day for one year. At the start and the end of this study, colonoscopic index and the amount of myeloperoxidase in a lavage solution were used as disease activity indices. Bacterial counts in the feces at the start and the end of this study were also examined. RESULTS: After a one-year treatment with the synbiotics, the clinical status of the UC patients as assessed by colonoscopy, significantly improved. Furthermore, the amount of myeloperoxidase in the lavage also decreased in these patients after the synbiotic treatment. The synbiotics significantly reduced the fecal counts of Bacteroidaceae and fecal pH. CONCLUSION: Administration of live B. breve strain Yakult and GOS can improve the clinical condition of patients with UC. These results encouraged us to perform a large-scale randomized, placebo-controlled trial.

Induction of colonic regulatory T cells by indigenous Clostridium species.

CD4(+) T regulatory cells (T(regs)), which express the Foxp3 transcription factor, play a critical role in the maintenance of immune homeostasis. Here, we show that in mice, T(regs) were most abundant in the colonic mucosa. The spore-forming component of indigenous intestinal microbiota, particularly clusters IV and XIVa of the genus Clostridium, promoted T(reg) cell accumulation. Colonization of mice by a defined mix of Clostridium strains provided an environment rich in transforming growth factor-ß and affected Foxp3(+) T(reg) number and function in the colon. Oral inoculation of Clostridium during the early life of conventionally reared mice resulted in resistance to colitis and systemic immunoglobulin E responses in adult mice, suggesting a new therapeutic approach to autoimmunity and allergy.

Effect of Lactobacillus casei on Streptococcus bovis in faecal flora.

Bacteraemia caused by Streptococcus bovis is often associated with colorectal tumours. Also, experimental studies have been proposed that S bovis acts as a promoter of tumours. We report the case of a man with colon adenoma who had a high proportion of S bovis in his faecal flora. He was treated with a Lactobacillus casei preparation (BLP) and the effect on the faecal flora was examined. L casei reduced the proportion of S bovis (from 43% down to 9%), and the effect continued after the administration of BLP was stopped. Our data indicate that BLP can repress the excessive colonisation of S bovis.

Induction of intestinal Th17 cells by segmented filamentous bacteria.

The gastrointestinal tract of mammals is inhabited by hundreds of distinct species of commensal microorganisms that exist in a mutualistic relationship with the host. How commensal microbiota influence the host immune system is poorly understood. We show here that colonization of the small intestine of mice with a single commensal microbe, segmented filamentous bacterium (SFB), is sufficient to induce the appearance of CD4(+) T helper cells that produce IL-17 and IL-22 (Th17 cells) in the lamina propria. SFB adhere tightly to the surface of epithelial cells in the terminal ileum of mice with Th17 cells but are absent from mice that have few Th17 cells. Colonization with SFB was correlated with increased expression of genes associated with inflammation and antimicrobial defenses and resulted in enhanced resistance to the intestinal pathogen Citrobacter rodentium. Thus, manipulation of this commensal-regulated pathway may provide new opportunities for enhancing mucosal immunity and treating autoimmune disease.

Rationale for Using of Bifidobacterium Probiotic Strains-Fermented Milk Against Colitis Based on Animal Experiments and Clinical Trials.

Probiotic foods such as probiotic strain-fermented milk or supplements proposing various health claims are now available. The beneficial effects of these probiotic foods on the digestive system are expected for not only healthy persons but also patients with diseases of the alimentary tract. This review focused on the rationale of using our Bifidobacterium strains-fermented milk as an adjunct for the prevention of recurrence or exacerbation of colitis. Animal experiments using gnotobiotic colitis or spontaneously colitis models and also human clinical trials of ulcerative colitis patients showed the potential of Bifidobacterium strains-fermented milk as a beneficial anti-colitis adjunct.

Anti-inflammatory activity of probiotic Bifidobacterium: enhancement of IL-10 production in peripheral blood mononuclear cells from ulcerative colitis patients and inhibition of IL-8 secretion in HT-29 cells.

AIM: To determine the anti-inflammatory activity of probiotic Bifidobacteria in Bifidobacteria-fermented milk (BFM) which is effective against active ulcerative colitis (UC) and exacerbations of UC, and to explore the immunoregulatory mechanisms. METHODS: Peripheral blood mononuclear cells (PBMNC) from UC patients or HT-29 cells were co-cultured with heat-killed probiotic bacteria or culture supernatant of Bifidobacterium breve strain Yakult (BbrY) or Bifidobacterium bifidum strain Yakult (BbiY) to estimate the amount of IL-10 or IL-8 secreted. RESULTS: Both strains of probiotic Bifidobacteria contained in the BFM induced IL-10 production in PBMNC from UC patients, though BbrY was more effective than BbiY. Conditioned medium (CM) and DNA of both strains inhibited IL-8 secretion in HT-29 cells stimulated with TNF-alpha, whereas no such effect was observed with heat-killed bacteria. The inhibitory effect of CM derived from BbiY was greater than that of CM derived from BbrY. DNAs of the two strains had a comparable inhibitory activity against the secretion of IL-8. CM of BbiY induced a repression of IL-8 gene expression with a higher expression of IkappaB-zeta mRNA 4 h after culture of HT-29 cells compared to that in the absence of CM. CONCLUSION: Probiotic Bifidobacterium strains in BFM enhance IL-10 production in PBMNC and inhibit IL-8 secretion in intestinal epithelial cells, suggesting that BFM has anti-inflammatory effects against ulcerative colitis.

Differential effects of two probiotic strains with different bacteriological properties on intestinal gene expression, with special reference to indigenous bacteria.

Probiotics are used for the improvement of gut disorders. To explore the potential of probiotics, a gnotobiotic study using BALB/c mice to analyze epithelial gene expression was performed. Microarray analysis of probiotic strain-monoassociated mice showed that Lactobacillus casei Shirota and Bifidobacterium breve Yakult noticeably affected gene expression in the ileal and colonic epithelial cells, respectively, although to a smaller extent than segmented filamentous bacteria (SFB). Lactobacillus casei Shirota enhanced the gene expression involving defense/immune functions and lipid metabolism more strongly than B. breve Yakult. In the colon, expression of a chloride transporter was slightly enhanced, although downregulation of many genes, such as guanine nucleotide-binding protein, was evident in mice with B. breve Yakult compared with the ones with L. casei Shirota. SFB affected gene expression more strongly than the probiotic strains. In particular, alpha(1-2) fucosyltransferase and pancreatitis-associated protein were significantly enhanced only in SFB-monoassociated mice but not probiotic strain-monoassociated mice. Gene expression of SFB-monoassociated mice was either stimulated or repressed in a manner similar to or opposite that of conventional colonized mice. Taken together, probiotic strains of L. casei Shirota and B. breve Yakult differentially affect epithelial gene expression in the small intestine and colon, respectively.

Prevention of gut inflammation by Bifidobacterium in dextran sulfate-treated gnotobiotic mice associated with Bacteroides strains isolated from ulcerative colitis patients.

Indigenous Bacteroides strains are closely associated with the occurrence and exacerbation of ulcerative colitis (UC). In this study, we aimed to clarify the effect of Bifidobacterium strains, another major member of colonic bacteria, on the development of gut inflammation using gnotobiotic mouse models associated with Bacteroides strains isolated from UC patients. Dextran sulfate (DSS) administration induced inflammation in the large intestine, in particular of the cecum, in the gnotobiotic mice associated with three strains of Bacteroides vulgatus, judging from the myeloperoxidase activity, occult blood score, and IgG leakage into the intestinal contents. However, the severity of the inflammation was greatly reduced in the gnotobiotic mice associated with both B. vulgatus and Bifidobacterium strains. The severity of the cecal inflammation was well correlated with the concentration of succinic acid in the cecum. Bacteriologically, the density of B. vulgatus strain A (BV-A) greatly decreased and the predominant strain changed from BV-A to BV-B on additional association with Bifidobacterium strains. Among gnotobiotic mice associated with a single B. vulgatus strain, the severity of cecal inflammation in BV-A-associated mice was greater than that in BV-B-associated mice. Each Bifidobacterium strain produced compound(s) more effectively inhibiting the growth of BV-A than BV-B in in vitro culture. Taken together, these results suggest that the severity of DSS-induced gut inflammation is closely associated with a particular B. vulgatus strain, and that Bifidobacterium strains may repress exacerbation of intestinal inflammation through growth inhibition of the B. vulgatus strain.

Randomized controlled trial of the effect of bifidobacteria-fermented milk on ulcerative colitis.

BACKGROUND: Alterations of intestinal flora, such as reduction in the concentration of bifidobacteria and increase in that of Bacteroides species, are apparently associated with the severity of ulcerative colitis. OBJECTIVE: We conducted a randomised clinical trial of the use of a bifidobacteria-fermented milk (BFM) supplement as a dietary adjunct in the treatment of ulcerative colitis. METHODS: The subjects were randomly divided into two groups: a group with BFM supplementation (BFM group, 11 subjects) and a control group (control group, 10 subjects). The BFM group was given 100 mL/day of BFM for one year. Colonoscopies, general blood markers and examinations of intestinal flora including the analysis of fecal organic acids were performed at the commencement of the study and after one year. RESULTS: Exacerbation of symptoms was seen in 3 out of 11 subjects in the BFM group and in 9 out of 10 in the control group. Log rank statistic analysis of the cumulative exacerbation rates showed a significant reduction in exacerbations for the BFM group (p = 0.0184). The analysis of microflora and the organic acids in the feces showed a significant reduction in the relative proportion of B. vulgatus in Bacteroidaceae and butyrate concentration, respectively, after supplementation with BFM, in comparison with before. CONCLUSION: Supplementation with the BFM product was successful in maintaining remission and had possible preventive effects on the relapse of ulcerative colitis.