Bifidobacterium infantis attenuates colitis by regulating T cell subset responses

AIM: to investigate the effect of Bifidobacterium infantis (B. infantis) on the T cell subsets and in attenuating the severity of experimental colitis in mice.

AIM:to investigate the effect of Bifidobacterium infantis(B.infantis)on the T cell subsets and in attenuating the severity of experimental colitis in mice.METHODS:Normal BALB/c mice were fed different doses of B.infantis for 3 wk,and T cell subsets and related cytokine profiles in mesenteric lymph nodes(MLNs)were detected by flow cytometry and realtime RT-PCR.Colitis was induced by administration of trinitrobenzene sulfonic acid(TNBS)in mice.Before colitis induction,mice were fed high dose B.infantisfor 3 wk.Cytokine profiles in MLNs and histological changes of colonic tissue were examined 6 d after colitis induction.RESULTS:No significant change in cytokine profiles was observed in normal mice fed low dose B.infantis.However,Th1-related cytokines(IL-2,IFN-γ,IL-12p40),Th17-related transcription factor and cytokines(RORγt,IL-21,IL-23),regulatory T cell(Treg)-related transcription factor and cytokines(Foxp3,IL-10)were increased in normal mice fed high dose B.infantis.Furthermore,flow cytometry assay showed B.infantis increased the numbers of CD4+Foxp3+Tregs and Th17cells in MLNs.Colitis was successfully induced by TNBS in mice,characterized by colonic inflammation and aberrant Th1 and Th17 responses.Feeding high dose B.infantis for 3 wk before colitis induction decreased the inflammatory cell infiltration and goblet cell depletion and restored the intestinal epithelium.In addition,B.infantis feeding reduced Th1-related cytokines(T-bet,IL-2 and IFN-γ)and Th17-related cytokines(IL-12p40,RORγt,IL-17A,IL-21 and IL-23),and increased Tregrelated molecules(Foxp3,IL-10 and TGF-β)in colitis mice.CONCLUSION:B.infantis effectively attenuates TNBSinduced colitis by decreasing Th1 and Th17 responses and increasing Foxp3+Treg response in the colonic mucosa.