Karen Madsen

Lactobacillus species prevents colitis in interleukin 10 gene–deficient mice

BACKGROUND & AIMS Intestinal luminal microflora, or their products, are likely an important initiating factor in the pathogenesis of inflammatory bowel disease. The aim of this study was to determine the role of colonic aerobic luminal bacteria and Lactobacillus species in the development of colitis in interleukin (IL)-10 gene-deficient mice. METHODS Intestine from 2-16-week-old mice was scored histologically and cultured for bacteria. Lactobacillus sp. repopulation of the colonic lumen was achieved via daily rectal delivery of Lactobacillus reuteri or oral lactulose therapy. RESULTS At 2 weeks of age, IL-10 gene-deficient mice showed no colonic injury but did display abnormal colonic bacterial colonization with increased colonic mucosal aerobic adherent and translocated bacteria in conjunction with reduced Lactobacillus sp. levels. In association with the abnormal colonic bacterial colonization, colitis developed by 4 weeks of age. Restoring Lactobacillus sp. to normal levels reduced levels of colonic mucosal adherent and translocated bacteria and attenuated the development of the colitis. CONCLUSIONS In the neonatal period, IL-10 gene-deficient mice have decreased levels of colonic Lactobacillus sp. and an increase in colonic mucosal adherent and translocated bacteria. Normalizing Lactobacillus sp. levels reduced colonic mucosal adherent and translocated bacteria and prevented colitis.

VSL#3 probiotic-mixture induces remission in patients with active ulcerative colitis.

BACKGROUND AND AIMS:Intestinal bacteria have been implicated in the initiation and perpetuation of IBD; in contrast, “probiotic bacteria” have properties possibly effective in treating and preventing relapse of IBD. We evaluated the safety and efficacy of VSL#3 and the components, and the composition of the biopsy-associated microbiota in patients with active mild to moderate ulcerative colitis (UC).METHODS:Thirty-four ambulatory patients with active UC received open label VSL#3, 3,600 billion bacteria daily in two divided doses for 6 wk. The presence of biopsy-associated bacteria was detected using a nucleic acid-based method and the presence of VSL#3 species confirmed by DNA sequencing of 16S rRNA.RESULTS:Thirty-two patients completed 6 wk of VSL#3 treatment and 2 patients did not have the final endoscopic assessment. Intent to treat analysis demonstrated remission (UCDAI ≤ 2) in 53% (n = 18); response (decrease in UCDAI ≥ 3, but final score ≥3) in 24% (n = 8); no response in 9% (n = 3); worsening in 9% (n = 3); and failure to complete the final sigmoidoscopy assessment in 5% (n = 2). There were no biochemical or clinical adverse events related to VSL#3. Two of the components of VSL#3 were detected by PCR/DGGE in biopsies collected from 3 patients in remission.CONCLUSION:Treatment of patients with mild to moderate UC, not responding to conventional therapy, with VSL#3 resulted in a combined induction of remission/response rate of 77% with no adverse events. At least some of the bacterial species incorporated in the probiotic product reached the target site in amounts that could be detected.

Secreted bioactive factors from Bifidobacterium infantis enhance epithelial cell barrier function

Live probiotic bacteria are effective in reducing gut permeability and inflammation. We have previously shown that probiotics release peptide bioactive factors that modulate epithelial resistance in vitro. The objectives of this study were to determine the impact of factors released from Bifidobacteria infantis on intestinal epithelial cell permeability and tight junction proteins and to assess whether these factors retain their bioactivity when administered to IL-10-deficient mice. B. infantis conditioned medium (BiCM) was applied to T84 human epithelial cells in the presence and absence of TNF-alpha and IFN-gamma. Transepithelial resistance (TER), tight junction proteins [claudins 1, 2, 3, and 4, zonula occludens (ZO)-1, and occludin] and MAP kinase activity (p38 and ERK) were examined. Acute effects of BiCM on intestinal permeability were assessed in colons from IL-10-deficient mice in Ussing chambers. A separate group of IL-1-deficient mice was treated with BiCM for 4 wk and then assessed for intestinal histological injury, cytokine levels, epithelial permeability, and immune response to bacterial antigens. In T84 cells, BiCM increased TER, decreased claudin-2, and increased ZO-1 and occludin expression. This was associated with enhanced levels of phospho-ERK and decreased levels of phospho-p38. BiCM prevented TNF-alpha- and IFN-gamma-induced drops in TER and rearrangement of tight junction proteins. Inhibition of ERK prevented the BiCM-induced increase in TER and attenuated the protection from TNF-alpha and IFN-gamma. Oral BiCM administration acutely reduced colonic permeability in mice whereas long-term BiCM treatment in IL-10-deficient mice attenuated inflammation, normalized colonic permeability, and decreased colonic and splenic IFN-gamma secretion. In conclusion, peptide bioactive factors from B. infantis retain their biological activity in vivo and are effective in normalizing gut permeability and improving disease in an animal model of colitis. The effects of BiCM are mediated in part by changes in MAP kinases and tight junction proteins.

Interleukin‐10 gene‐deficient mice develop a primary intestinal permeability defect in response to enteric microflora

The normal intestinal epithelium provides a barrier relatively impermeable to luminal constituents. However, patients with inflammatory bowel disease experience enhanced intestinal permeability that correlates with the degree of injury. IL-10 gene-deficient mice were studied to determine whether increased intestinal permeability occurs as a primary defect before the onset of mucosal inflammation or is secondary to mucosal injury. At 2 weeks of age, IL-10 gene-deficient mice show an increase in ileal and colonic permeability in the absence of any histological injury. This primary permeability defect is associated with increased mucosal secretion of interferon-gamma and tumor necrosis factor-alpha, and does not involve an increase in nitric oxide synthase activity. Colonic permeability remains elevated as inflammation progresses, while ileal permeability normalizes by 6 weeks of age. IL-10 gene-deficient mice raised under germ-free conditions have no inflammation, and demonstrate normal permeability and cytokine levels. This data suggests that the intestinal permeability defect in IL-10 gene-deficient mice occurs due to a dysregulated immune response to normal enteric microflora and, furthermore, this permeability defect exists prior to the development of mucosal inflammation.

Antibiotic therapy attenuates colitis in interleukin 10 gene–deficient mice☆☆☆

BACKGROUND & AIMS Interleukin (IL)-10 gene-deficient mice, raised under germfree conditions, do not develop colitis, implying a role for bacteria. This study mapped the appearance of luminal colonic bacteria and, using antibiotic treatment, determined their association with colitis in IL-10 gene-deficient mice. METHODS Mice were treated with ciprofloxacin or with neomycin and metronidazole. The intestine was harvested for histological scoring and bacterial assessment. RESULTS At 2 weeks of age, before the development of colitis, IL-10 gene-deficient mice demonstrated an earlier appearance of Streptococcus and Clostridium sp., and had a greater proportion (P < 0.01) of bacteria adherent to the colonic mucosa. This pattern of increased adherent bacteria persisted for the 12 weeks of study. Treatment of mice before the onset of colonic inflammation, with either antibiotic regime, reduced mucosal adherent bacteria and prevented colitis (P < 0.01). In contrast, treatment of established colitis with neomycin and metronidazole did not reduce adherent bacterial levels, yet was more efficacious (P < 0.05) in treating established colitis than ciprofloxacin, which did reduce adherent colonic bacteria. CONCLUSIONS In the IL-10 gene-deficient mouse model, the appearance and number of mucosal adherent colonic bacteria are altered before the onset of colitis. Antibiotics both prevent and treat the colitis through correction of this primary bacterial alteration.

Reducing small intestinal permeability attenuates colitis in the IL10 gene-deficient mouse

Background: Defects in the small intestinal epithelial barrier have been associated with inflammatory bowel disease but their role in the causation of disease is still a matter of debate. In some models of disease increased permeability appears to be a very early event. The interleukin 10 (IL10) gene-deficient mouse spontaneously develops colitis after 12 weeks of age. These mice have been shown to have increased small intestinal permeability that appears early in life. Furthermore, the development of colitis is dependent upon luminal agents, as animals do not develop disease if raised under germ-free conditions. Aims: To determine if the elevated small bowel permeability can be prevented, and if by doing so colonic disease is prevented or attenuated. Methods: IL10 gene-deficient (IL10−/−) mice) were treated with AT-1001 (a zonulin peptide inhibitor), a small peptide previously demonstrated to reduce small intestinal permeability. Small intestinal permeability was measured, in vivo, weekly from 4 to 17 weeks of age. Colonic disease was assessed at 8 weeks in Ussing chambers, and at 17 weeks of age inflammatory cytokines and myeloperoxidase were measured in the colon. Colonic permeability and histology were also endpoints. Results: Treated animals showed a marked reduction in small intestinal permeability. Average area under the lactulose/mannitol time curve: 5.36 (SE 0.08) in controls vs 3.97 (SE 0.07) in the high-dose AT-1001 group, p<0.05. At 8 weeks of age there was a significant reduction of colonic mucosal permeability and increased electrical resistance. By 17 weeks of age, secretion of tumour necrosis factor α (TNFα) from a colonic explant was significantly lower in the treated group (25.33 (SE 4.30) pg/mg vs 106.93 (SE 17.51) pg/ml in controls, p<0.01). All other markers also demonstrated a clear reduction of colitis in the treated animals. Additional experiments were performed which demonstrated that AT-1001 was functionally active only in the small intestine. Conclusions: This work suggests that increased intestinal permeability may be an important aetiological event in the development of colitis in IL10−/− mice.

Recommendations for Probiotic Use—2011 Update

This study describes the consensus opinion of the participants of the third Yale Workshop on probiotic use. There were 10 experts participating. The recommendations update those of the first 2 meetings that were published in 2005 and 2008. The workshop presentations and papers in this supplement relate to the involvement of normal microbiota involved in intestinal microecology, how the microbes interact with the intestine to affect our immunologic responses, the stability and natural history of probiotic organisms, and the role of the intestinal microbatome with regard to affecting cardiac risk factors and obesity. Recommendations for the use of probiotics in necrotizing enterocolitis, childhood diarrhea, inflammatory bowel disease, irritable bowel syndrome, and Clostridium difficile diarrhea are reviewed. As in previous publications, the recommendations are given as A, B, or C ratings. The recent positive experiences with bacteriotherapy (fecal microbiome transplant) are also discussed in detail and a positive recommendation is made for use in severe resistant C. difficile diarrhea.

Probiotics and the management of inflammatory bowel disease

The demonstration that immune and epithelial cells can discriminate between different microbial species has extended our understanding of the actions of probiotics beyond simple barrier and antimicrobial concepts. Several probiotic mechanisms of action, relative to inflammatory bowel disease, have been elucidated: (1) competitive exclusion, whereby probiotics compete with microbial pathogens for a limited number of receptors present on the surface epithelium; (2) immunomodulation and/or stimulation of an immune response of gut-associated lymphoid and epithelial cells; (3) antimicrobial activity and suppression of pathogen growth; (4) enhancement of barrier function; and (5) induction of T cell apoptosis in the mucosal immune compartment. The unraveling of these mechanisms of action has led to new support for the use of probiotics in the management of clinical inflammatory bowel disease. Though level 1 evidence now supports the therapeutic use of probiotics in the treatment of postoperative pouchitis, only levels 2 and 3 evidence is currently available in support of the use of probiotics in the treatment of ulcerative colitis and Crohns disease. Nevertheless, one significant and consistent finding has emerged during the course of research in the past year: not all probiotic bacteria have similar therapeutic effects. Rigorously designed, controlled clinical trials are vital to investigate the unresolved issues related to efficacy, dose, duration of use, single or multi-strain formulation, and the concomitant use of probiotics, synbiotics, or antibiotics.

Interleukin 10 prevents cytokine-induced disruption of T84 monolayer barrier integrity and limits chloride secretion

BACKGROUND & AIMS The proinflammatory cytokine interferon gamma (IFN-gamma) disrupts epithelial barrier integrity and attenuates secretagogue-induced chloride secretion. This study tested the efficacy of the anti-inflammatory cytokine interleukin 10 (IL-10) in maintaining epithelial barrier and chloride secretory function in the presence of IFN-gamma. METHODS T84 epithelial cell monolayers were treated with IL-10, IFN-gamma, or IFN-gamma plus IL-10. Monolayer barrier integrity was assessed by measurements of electrical conductance, unidirectional mannitol and inulin fluxes, and tight junctional charge selectivity in Ussing chambers. Short-circuit current (Isc) was measured in response to carbachol and forskolin stimulation. RESULTS IL-10 attenuated the IFN-gamma-induced increase in electrical conductance and totally prevented the IFN-gamma-induced increase in mannitol and inulin fluxes. IL-10 did not prevent the IFN-gamma-induced abolishment of tight junctional charge selectivity but did attenuate the total increase in sodium and chloride permeability. IFN-gamma and IL-10 both separately reduced peak forskolin and carbachol-stimulated Isc. IL-10 pretreatment further enhanced the IFN-gamma-induced reduction in secretagogue-induced Isc. CONCLUSIONS In T84 epithelial monolayers, IL-10 maintains the size, but not the charge, selectivity of the epithelial tight junction in the presence of IFN-gamma. In addition, both IL-10 and IFN-gamma limit carbachol and forskolin-induced increase in Isc.

Human gut microbiota and its relationship to health and disease

Probiotics are live microorganisms that confer a health benefit on the host when administered in appropriate amounts. Over 700 randomized, controlled, human studies have been conducted with probiotics thus far, with the results providing strong support for the use of probiotics in the clinical prevention or treatment of gastrointestinal tract disorders and metabolic syndrome. The present review is based on webinar presentations that were developed by the American Gastroenterological Association (AGA) in partnership with the International Scientific Association for Probiotics and Prebiotics (ISAPP) and the North American branch of the International Life Sciences Institute (ILSI North America). The presentations provided gastroenterologists and researchers with fundamental and current scientific information on the influence of gut microbiota on human health and disease, as well as clinical intervention strategies and practical guidelines for the use of probiotics and prebiotics.