Curcumin ameliorates DSS-induced colitis in mice by regulating the Treg/Th17 signaling pathway

Curcumin has a therapeutic effect on ulcerative colitis, but the underlying mechanism has yet to be elucidated. The aim of the present study was to clarify the possible mechanisms. Dextran sulfate sodium-induced colitis mice were treated with curcumin via gavage for 7 days. The effects of curcumin on disease activity index (DAI) and pathological changes of colonic tissue in mice were determined. Interleukin (IL)-6, IL-10, IL-17 and IL-23 expression levels were measured by ELISA. Flow cytometry was used to detect the ratio of mouse spleen regulatory T cells (Treg)/Th17 cells, and western blotting was used to measure the nuclear protein hypoxia inducible factor (HIF)-1α level. The results demonstrated that curcumin can significantly reduce DAI and spleen index scores and improve mucosal inflammation. Curcumin could also regulate the re-equilibration of Treg/Th17. IL-10 level in the colon was significantly increased, while inflammatory cytokines IL-6, IL-17 and IL-23 were significantly reduced following curcumin treatment. No significant difference in HIF-1α was observed between the colitis and the curcumin group. It was concluded that oral administration of curcumin can effectively treat experimental colitis by regulating the re-equilibration of Treg/Th17 and that the regulatory mechanism may be closely related to the IL-23/Th17 pathway. The results of the present study provided molecular insight into the mechanism by which curcumin treats ulcerative colitis.