Probiotic administration alters the gut flora and attenuates colitis in mice administered dextran sodium sulfate

Streptococcus thermophilus ST28 ameliorates colitis in mice partially by suppression of inflammatory Th17 cells

The effects of Streptococcus thermophilus ST28 on cytokine production by murine splenocytes stimulated with transforming growth factor-β plus interleukin- (IL-) 6 were evaluated. The addition of ST28 significantly repressed IL-17 production compared to ATCC 19258 (type strain). ST28 also decreased the number of Th17 cells in the stimulated splenocytes. The anti-inflammatory effects of ST28 administration were evaluated in mice with colitis induced by dextran sodium sulphate (DSS). Oral treatment of mice with ST28 ameliorated the intestinal lesions by DSS. Upon DSS treatment, IL-17 production in lamina propria lymphocytes (LPLs) was induced, but ST28 significantly decreased its production. ST28 also decreased the percentage of Th17 cells in LPL from DSS-induced colitis. The present results imply that ST28 suppresses the Th17 response in inflamed intestines and would be useful in the treatment of Th17-mediated diseases, such as inflammatory bowel disease.

Lessons from probiotic-host interaction studies in murine models of experimental colitis

In inflammatory bowel diseases (IBD), it is known that besides genetic and environmental factors (e.g. diet, drugs, stress), the microbiota play an important role in the pathogenesis. Patients with IBD have an altered microbiota (dysbiosis) and therefore, probiotics, defined as 'live micro-organisms that when administered in adequate amounts can confer a health benefit on the host', have been suggested as nutritional supplements to restore these imbalances. The best response on probiotics among the different types of IBD appears to be in the case of ulcerative colitis. Although probiotics show promise in IBD in both clinical and animal studies, further mechanistic studies are necessary to optimize the use of probiotics as supporting therapy in IBD. Murine models of experimental colitis have been used for decades to study this pathology, and these models have been proven useful to search for new therapeutic approaches. The purpose of this review is to summarize probiotic-host interaction studies in murine models of experimental colitis and to evaluate how these models can further help in understanding these complex interactions. Unraveling the molecular mechanisms behind the beneficial effects will assist in better and possibly more efficient probiotic formulations.

Rectal administration of Lactobacillus casei DG modifies flora composition and Toll-like receptor expression in colonic mucosa of patients with mild ulcerative colitis

BACKGROUND

An imbalance in gut microbiota seems to contribute to the development of chronic inflammatory disorders of the gastrointestinal tract, such as ulcerative colitis (UC). Although it has been suggested that probiotic supplementation is an effective approach to colitis, its effects on intestinal flora and on mucosal cytokine balance have never been explored.

AIM

To evaluate the effect of Lactobacillus casei (L. casei) DG, a probiotic strain, on colonic-associated microbiota, mucosal cytokine balance, and toll-like receptor (TLR) expression.

METHODS

Twenty-six patients with mild left-sided UC were randomly allocated to one of three groups for an 8-week treatment period: the first group of 7 patients received oral 5-aminosalicylic acid (5-ASA) alone, the second group of 8 patients received oral 5-ASA plus oral L. casei DG, and the third group of 11 patients received oral 5-ASA and rectal L. casei DG. Biopsies were collected from the sigmoid region to culture mucosal-associated microbes and to assess cytokine and TLR messenger RNA (mRNA) levels by quantitative real-time polymerase chain reaction (RT-PCR).

RESULTS

5-ASA alone or together with oral L. casei DG failed to affect colonic flora and TLR expression in a significant manner, but when coupled with rectally administered L. casei DG, it modified colonic microbiota by increasing Lactobacillus spp. and reducing Enterobacteriaceae. It also significantly reduced TLR-4 and interleukin (IL)-1β mRNA levels and significantly increased mucosal IL-10.

CONCLUSIONS

Manipulation of mucosal microbiota by L. casei DG and its effects on the mucosal immune system seem to be required to mediate the beneficial activities of probiotics in UC patients.

Administration of Lactobacillus plantarum reduces TNBS-induced colitis in mice

AIM: To determine the effect of administration of Lactobacillus plantarum (LP) on established colitis in mice and to explore possible mechanisms involved.

METHODS: A model of colitis was induced by intracolonic injection of 2,4,6-trinitrobenzene sulfonic acid sodium salt (TNBS) in adult Balb/c mice. The mice were then treated with LP (10⁹ CFU) or vehicle for three weeks. After treatment, all mice were killed and colonic damage was evaluated both histologically and biochemically, including determination of the activity of myeloperoxidase (MPO) activity, and the levels of leukotriene B4 (LTB4), tumor necrosis factor α (TNF-α) and interferon-γ (IFN-γ) in colon tissue.

RESULTS: LP therapy resulted in amelioration of colitis induced with TNBS in mice when compared with control mice without undergoing LP treatment. This anti-inflammatory effect of LP was evidenced by a significant reduction of macroscopic and microscopic colonic damage scores (1.11 ± 0. 61 vs 4.62 ± 0. 40, P < 0.05; 1.48 ± 0.40 vs 5.39 ± 1.12, P < 0.05). Moreover, a reduction of neutrophil infiltrate in LP-treated mice was confirmed biochemically by a significant reduction of the activity of colonic MPO (25.14 U/g ± 5.22 U/g vs 90.3 U/g ± 7.70 U/g, P < 0.05), a marker of neutrophil infiltration, in comparison with non-treated colitic mice. In addition, treatment with LP resulted in a lower colonic content of LTB4 and in a significant reduction of proinflammatory factors, such as TNF-α and IFN-γ, when compared with control mice (3.13 ng/g ± 0.10 ng/g vs 8.43 ng/g ± 0. 49 ng/g, P < 0.05; 205 ng/g ± 68 ng/g vs 375 ng/g ± 79 ng/g, P < 0.05; 446 ng/g ± 116 ng/g vs 603 ng/g ± 109 ng/g, P < 0.05).

CONCLUSION: Administration of LP is effective in accelerating the recovery of experimental colitis in mice possibly by reducing leukocyte accumulation and proinflammatory cytokine expression.

Treatment of irritable bowel syndrome: beyond fiber and antispasmodic agents

Irritable bowel syndrome (IBS) is a chronic functional disorder of the gastrointestinal tract of unknown etiology. The diagnosis of IBS is made clinically, using symptom-based criteria such as the Manning or Rome criteria. Medical therapy for this condition has traditionally been directed towards symptom relief, using fiber or antispasmodic agents. In recent years, emerging data have confirmed the efficacy of antidepressants, psychological therapies, 5-HT(3) antagonists, 5-HT(4) agonists, and probiotics in the short-term treatment of IBS, although whether these therapies influence the long-term course of the disease is unknown. Increasing knowledge regarding the pathophysiological mechanisms underlying IBS has resulted in a number of novel molecular treatments, which show promise. These include therapies targeting gastrointestinal mucosal chloride channels and guanylate cyclase-C receptors, as well as highly selective agents influencing serotonergic transmission that, at the time of writing, do not appear to have any severe deleterious effects. In this article we provide a summary of current and emerging therapies in this field.

Treatment with Bifidobacterium bifidum 17 partially protects mice from Th1-driven inflammation in a chemically induced model of colitis

Probiotics have been suggested as an alternative therapeutical approach in the intervention of inflammatory disorders of the gastrointestinal tract (GIT). Application of single strains or probiotic mixtures has shown promising results in animal models and patients of inflammatory bowel disease (IBD). We recently demonstrated potent inhibitory capacity of a Bifidobacterium bifidum S17 on LPS-induced inflammatory events in cell culture models using intestinal epithelial cells and verified these anti-inflammatory effects in two mouse models of colitis. In the present study we analyze the anti-inflammatory effect of this potential probiotic strain in a chemically-induced model of colitis in C57BL/6 mice. This model is characterized by a strong type 1T helper (Th1) response resembling Crohn's disease, one of the two most prevalent forms of IBD. We performed macroscopic analysis and determined the effect of B. bifidum S17 on the cytokine balance in biopsies of the colonic mucosa. While treatment with B. bifidum S17 only had a marginal effect on weight loss, no difference was observed in the macroscopic parameters. However, a significant reduction in histology scores and the levels of pro-inflammatory cytokines interleukin 1β (IL-1β), interleukin 6 (IL-6), keratinocyte-derived chemokine (KC) and the inflammatory markers cyclooxigenase 2 (Cox-2) and myeloperoxidase (MPO) was observed. These results indicate that treatment with B. bifidum S17 is able to partially inhibit the strong Th1-driven intestinal inflammation induced in our model of colitis.

Milk sialyllactose influences colitis in mice through selective intestinal bacterial colonization

Milk oligosaccharides contribute to the development of the intestinal environment by acting as decoy receptors for pathogens and as prebiotics, which promote the colonization of commensal bacteria. Here, using α2,3- and α2,6-sialyltransferase-deficient mice, we investigated the role of the sialylated milk oligosaccharides sialyl(α2,3)lactose and sialyl(α2,6)lactose on mucosal immunity. The exposure of newborn mice to milk containing or deficient in sialyllactose had no impact on the development of mucosal leukocyte populations. However, when challenged by dextran sulfate sodium (DSS) in drinking water, adult mice that had been fostered on sialyl(α2,3)lactose-deficient milk were more resistant to colitis compared with mice fostered on normal milk or sialyl(α2,6)lactose-deficient milk. Analysis of intestinal microbiota showed different colonization patterns depending on the presence or absence of sialyl(α2,3)lactose in the milk. Germ-free mice reconstituted with intestinal microbiota isolated from mice fed on sialyl(α2,3)lactose-deficient milk were more resistant to DSS-induced colitis than germ-free mice reconstituted with standard intestinal microbiota. Thus, exposure to sialyllactose during infancy affects bacterial colonization of the intestine, which influences the susceptibility to DSS-induced colitis in adult mice.

Effects of fructo-oligosaccharide on DSS-induced colitis differ in mice fed nonpurified and purified diets

We investigated whether feeding a purified compared with nonpurified diet supplemented with or without fructo-oligosaccharide (FOS; 50 g/kg diet) altered the response of C57BL/6 mice to DSS-induced diarrhea. In Expt. 1, we examined disease severity in mice receiving DSS (2% in drinking water) for 5 d. In Expt. 2, we measured cecal organic acid concentrations and fecal water-holding capacity (WHC). In Expts. 3 and 4, we tested whether polycarbophil calcium (PC), a water-absorbing polymer, altered fecal WHC and disease severity. FOS exacerbated diarrhea and weight loss in mice fed the purified diet and reduced fecal bleeding in mice fed the nonpurified diet (P < 0.05). Without DSS administration, cecal acetate and butyrate concentrations were higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). Fecal WHC was higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). One day after starting DSS administration, cecal succinate concentrations were higher in mice fed the FOS-supplemented purified diet than in mice fed the other 3 diets, whereas SCFA concentrations were higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). PC supplementation increased fecal WHC and prevented FOS exacerbation of diarrhea in mice fed the purified diet (P < 0.05). We conclude that the effects of FOS on DSS-induced diarrhea differ in mice fed the purified and nonpurified diets. The protective effect of nonpurified diet was associated with increased production of organic acids and WHC in the intestinal contents.

Distribution, detection of enterotoxigenic strains and antimicrobial drug susceptibility patterns of bacteroides fragilis group in diarrheic and non-diarrheic feces from brazilian infants

Despite the importance of gastrointestinal diseases and their global distribution, affecting millions of individuals around the world, the role and antimicrobial susceptibility patterns of anaerobic bacteria such as those in the Bacteroides fragilis group (BFG) are still unclear in young children. This study investigated the occurrence and distribution of species in the BFG and enterotoxigenic strains in the fecal microbiota of children and their antimicrobial susceptibility patterns. Diarrheic (n=110) and non-diarrheic (n=65) fecal samples from children aged 0-5 years old were evaluated. BFG strains were isolated and identified by conventional biochemical, physiological and molecular approaches. Alternatively, bacteria and enterotoxigenic strains were detected directly from feces by molecular biology. Antimicrobial drug susceptibility patterns were determined by the agar dilution method according to the guidelines for isolated bacteria. BFG was detected in 64.3% of the fecal samples (55% diarrheic and 80.4% non-diarrheic), and 4.6% were enterotoxigenic. Antimicrobial resistance was observed against ampicillin, ampicillin/sulbactam, piperacillin/tazobactam, meropenem, ceftriaxone, clindamycin and chloramphenicol. The data show that these bacteria are prevalent in fecal microbiota at higher levels in healthy children. The molecular methodology was more effective in identifying the B. fragilis group when compared to the biochemical and physiological techniques. The observation of high resistance levels stimulates thoughts about the indiscriminate use of antimicrobial drugs in early infancy. Further quantitative studies are needed to gain a better understanding of the role of these bacteria in acute diarrhea in children.

1H NMR-based metabonomic assessment of probiotic effects in a colitis mouse model

Metabolic profiling of the fecal extracts of male mice was carried out to assess the effects of probiotics on colonic inflammation using (1)H NMR spectroscopy coupled with multivariate data analysis. The control group (n = 5) was administered phosphate buffered saline for 14 days. Acute colitis was induced with dextran sulfate sodium (DSS) for 7 days following administration of phosphate buffered saline for 7 days (DSS-treated group, n = 5). LAB + DSS-treated group (n = 5) was administered lactic acid bacteria (LAB) daily for 7 days followed by treatment with DSS for 7 days to investigate protective effect of LAB against DSS-inducible colitis. Histological damage, myeloperoxidase activity, and malondialdehyde content of colon tissue were reduced, whereas colon length increased in LAB + DSS-treated mice compared to those in DSS-treated mice. DSS treatment was associated with fecal excretion of amino acids, short chain fatty acids, and nucleotides, revealing significant decreases of threonine, alanine, glutamate, glutamine, aspartate, lysine, glycine, butyrate, uracil, and hypoxanthine together with increases of monosaccharides, glucose, and trimethylamine in the feces of mice with DSS-induced colitis. Increased levels of acetate, butyrate, and glutamine and decreased levels of trimethylamine were found in the feces of LAB + DSS-treated mice compared to DSS-treated mice alone. The increased short chain fatty acids levels in the feces of mice fed with LAB indicate that the probiotics have protective effects against DSS-induced colitis via modulation of the gut microbiota. This work highlights the possibility for alternative approach of metabonomics in feces for assessing the probiotic effect in an animal model of inflammatory bowel disease.

A pathobiont of the microbiota balances host colonization and intestinal inflammation

The gastrointestinal tract harbors a diverse microbiota that has coevolved with mammalian hosts. Though most associations are symbiotic or commensal, some resident bacteria (termed pathobionts) have the potential to cause disease. Bacterial type VI secretion systems (T6SSs) are one mechanism for forging host-microbial interactions. Here we reveal a protective role for the T6SS of Helicobacter hepaticus, a Gram-negative bacterium of the intestinal microbiota. H. hepaticus mutants with a defective T6SS display increased numbers within intestinal epithelial cells (IECs) and during intestinal colonization. Remarkably, the T6SS directs an anti-inflammatory gene expression profile in IECs, and CD4+ T cells from mice colonized with T6SS mutants produce increased interleukin-17 in response to IECs presenting H. hepaticus antigens. Thus, the H. hepaticus T6SS limits colonization and intestinal inflammation, promoting a balanced relationship with the host. We propose that disruption of such balances contributes to human disorders such as inflammatory bowel disease and colon cancer.

Impact of inulin and a multispecies probiotic formulation on performance, microbial ecology and concomitant fermentation patterns in newly weaned piglets

The effect of inulin and a multispecies probiotic formulation on performance and microbial parameters in a 28 days feeding trial with newly weaned piglets was assessed. Forty-eight piglets were allocated to a 2 × 2 factorial experiment involving two levels of inulin supplementation (0% or 0.4%) and two levels of probiotics (0 or 1 × 10(9) CFU/kg as fed, comprising enterococci, lactobacilli and bifidobacteria). In digesta samples obtained at slaughter (stomach, jejunum, ileum and colon), selected bacterial groups were enumerated and lactic acid, short chain fatty acids and ammonia concentrations analysed. The overall performance of piglets was unaffected by treatment. Inulin increased total aerobes in stomach and jejunum (p < 0.05), whereas enterococci declined in colon of the inulin group (p < 0.05). Furthermore decreasing colonic acetic acid (p < 0.01) and increasing lactic acid (p < 0.05) was observed for inulin. Probiotics increased total aerobes (p < 0.05) and enterococci (p < 0.01) in ileum and lactobacilli (p < 0.05), enterococci and gram-negative anaerobes (p < 0.01) in colon. Moreover, dry matter content in stomach and colon was lower and acetic acid in colon increased (p < 0.05). A decrease in ileal pH value was noted symbiotically for both additives. However, several parameters showed no synbiotic, but distinct individual effects of inulin and probiotics. Effects occurred along the entire gastrointestinal tract without restriction to the colon.

Recent developments and perspectives in the investigation of probiotic effects

The quest for a better understanding of how probiotics work has boosted an enormous interest in the molecular processes underlying host-microbe interactions. This review covers recent developments and perspectives in the study of probiotic mechanisms.

Comparison of the immunomodulatory properties of three probiotic strains of Lactobacilli using complex culture systems: prediction for in vivo efficacy

Background

While the use of probiotics to treat or prevent inflammatory bowel disease (IBD) has been proposed, to this point the clinical benefits have been limited. In this report we analyzed the immunological activity of three strains of Lactobacillus to predict their in vivo efficacy in protecting against experimental colitis.

Methodology/Principal Findings

We compared the immunological properties of Lactobacillus plantarum NCIMB8826, L. rhamnosus GG (LGG), L. paracasei B21060 and pathogenic Salmonella typhimurium (SL1344). We studied the stimulatory effects of these different strains upon dendritic cells (DCs) either directly by co-culture or indirectly via conditioning of an epithelial intermediary. Furthermore, we characterized the effects of these strains in vivo using a Dextran sulphate sodium (DSS) model of colitis.

We found that the three strains exhibited different abilities to induce inflammatory cytokine production by DCs with L. plantarum being the most effective followed by LGG and L. paracasei. L. paracasei minimally induced the release of cytokines, while it also inhibited the potential of DCs to both produce inflammatory cytokines (IL-12 and TNF-α) and to drive Th1 T cells in response to Salmonella. This effect on DCs was found under both direct and indirect stimulatory conditions – i.e. mediated by epithelial cells - and was dependent upon an as yet unidentified soluble mediator. When tested in vivo, L. plantarum and LGG exacerbated the development of DSS-induced colitis and caused the death of treated mice, while, conversely L. paracasei was protective.

Conclusions

We describe a new property of probiotics to either directly or indirectly inhibit DC activation by inflammatory bacteria. Moreover, some immunostimulatory probiotics not only failed to protect against colitis, they actually amplified the disease progression. In conclusion, caution must be exercised when choosing a probiotic strain to treat IBD.