Eubacterium limosum ameliorates experimental colitis and metabolite of microbe attenuates colonic inflammatory action with increase of mucosal integrity.

AIM: To examine the effect of Eubacterium limosum (E. limosum) on colonic epithelial cell line in vitro, and to evaluate the effect of E. limosum on experimental colitis.
METHODS: E. limosum was inoculated anaerobically and its metabolites were obtained. The growth stimulatory effect of the E. limosum metabolites on T84 cells was evaluated by SUDH activity, and the anti-inflammatory effect by IL-6 production. The change in mRNA of toll like receptor 4 (TLR4) was evaluated by real time PCR. Colitis was induced by feeding BALB/C mice with 2.0% dextran sodium sulfate. These mice received either 5% lyophilized E. limosum (n = 7) or control diet (n = 7). Seven days after colitis induction, clinical and histological scores, colon length, and cecal organic acid levels were determined.
RESULTS: The E. limosum produced butyrate, acetate, propionate, and lactate at 0.25, 1.0, 0.025 and 0.07 mmol/L, respectively in medium. At this concentration, each acid had no growth stimulating activity on T84 cells; however, when these acids were mixed together at the above levels, it showed significantly high activity than control. Except for lactate, these acids significantly attenuated IL-6 production at just 0.1 mmol/L. In addition, under TNF-alpha stimulation, butyrate attenuated the production of TLR4 mRNA. The treatment with E. limosum significantly attenuated clinical and histological scores of colitis with an increase of cecal butyrate levels, compared with the control group.
CONCLUSION: E. limosum can ameliorate experimental colonic inflammation. In part, the metabolite of E. limosum, butyrate, increases mucosal integrity and shows anti-inflammatory action modulation of mucosal defense system via TLR4.