Bifidobacteria alleviate experimentally induced colitis by upregulating indoleamine 2, 3-dioxygenase expression

摘要

The goal of this study was explore the role of indoleamine 2, 3-dioxygenase (IDO) in the therapeutic effect of probiotics on inflammatory bowel disease (IBD). Trinitrobenzene sulfonic acid (TNBS) was used to induce colitis in mice and 1-methyltryptophan (1-MT) to block expression of IDO. Clinical manifestations and macroscopic and microscopic colonic changes were assessed using a disease activity index (DAI), the Wallace-Keenan, and Curtner scoring systems, respectively. Expression of colonic IDO was detected by western blot. Immunohistochemistry analysis to evaluate numbers of CD11c(+) cells and expression of IL-17 and Foxp3 showed that DAI, Wallace-Keenan, and Curtner scores were lower in the Bifidobacteria treatment group than the control group and that the therapeutic effect of Bifidobacteria was blocked by 1-MT (P&0.05). Additionally, Bifidobacteria were found to increase expression of IDO and the numbers of CD11c(+) cells, CD11c(+) and IDO double positive cells and Foxp3(+) Treg cells, while decreasing the number of IL-17(+)cells (P&0.05). The generation of Foxp3(+) Treg cells induced by Bifidobacteria was abrogated by 1-MT (P&0.05). These findings study suggest that Bifidobacteria attenuate TNBS-induced colitis by inducing expression of IDO, which further increases generation of Foxp3(+) Treg cells.