Upregulation of intestinal Barrier Function in Mice with Dss-induced colitis by a Defined Bacterial consortium is associated with expansion of IL-17A Producing gamma Delta T cells

Bacterial consortium transplantation (BCT) is a promising alternative to fecal microbiota transplantation in treating inflammatory bowel disease (IBD). Here, we showed that a defined bacterial consortium derived from healthy mice was able to enhance the intestinal barrier function of mice with dextran sulfate sodium (DSS)-induced colitis. Interestingly, we found that the bacterial consortium significantly promoted the expansion of IL-17Aproducing.dT (gamma delta T17) cells in colonic lamina propria, which was closely associated with changing of intestinal microbial composition. The increased IL-17A secretion upon treatment with microbial products derived from the bacterial consortium was accompanied with upregulation of TLR2 expression by gamma delta T cells, and it might be responsible for the upregulation of mucosal barrier function through IL-17R-ACT1-mediated recovery of the disrupted occludin subcellular location. Changing of some specific microbial groups such as Bifidobacterium and Bacillus spp. was closely correlated with the promotion of TLR2+gamma delta T cells. Our results support that BCT can restore the alliance between commensal microbiota and intestinal gamma delta T cells, which contributes to the improvement of intestinal barrier function. This study provides new insight into the development of bacteria transplantation therapy for the treatment of IBD.