[Xiezhuo Jiedu Recipe improves ulcerative colitis in rats by regulating Th17/Treg immune balance]

To explore the mechanism of Xiezhuo Jiedu Recipe (XZJD) for improving ulcerative colitis (UC).

SD rat models of UC were randomized into 5 groups (n=10) for daily gavage with saline, mesalamine, or low-, medium- or high-dose XZJD for 14 days, with 10 normal rats with saline gavage as the control group. Pathological changes in the colon of the rats were observed using HE staining, and serum IL-6, IL-10 and IL-17 levels and their expressions in the colon tissues were determined with ELISA and immunohistochemistry. The expressions of occludin and ZO-1 and percentages of Th17 and Treg cells in the colon tissues were detected using immunofluorescence staining and flow cytometry; the mRNA and protein expressions of ROR-γt and Foxp3 were detected with RT-PCR and Western blotting.

The rat models of UC showed obvious colonic mucosal damage with massive inflammatory cell infiltration, increased IL-6 and IL-17 levels and lowered IL-10 level in both the serum and colonic tissues, reduced expression levels of occludin and ZO-1, increased Th17 and lowered Treg cell percentages, increased RORγt mRNA and protein expressions, and reduced Foxp3 mRNA and protein expressions in the colonic tissue. Treatment with XZJD significantly alleviated inflammatory response in the colonic mucosa and effectively reversed the changes in IL-6, IL-17 and IL-10 levels, expressions of occludin and ZO-1, percentages of Th17 and Treg cells, and the expressions of RORγt and Foxp3 in the colonic tissues of UC rats.

XZJD can alleviate pathologies in the colonic mucosa in UC rats possibly by regulating Th17/Treg immune balance.