Abstract: Objective To investigate the therapeutic mechanism of diosmetin on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced Crohn's disease (CD)-like colitis in mice. Methods Wild-type C57BL/6 mice were randomized into control group, TNBS-induced CD-like colitis group (TNBS group) and 50 mg · kg- 1 · d- 1 diosmetin-treated group (n=8). Disease activity (DAI) scores, body weight changes, histological scores, colon lengths and colon mucosal levels of TNF-α, IFN-γ, and IL-17A were measured to evaluate the severity of colitis. The changes of T lymphocyte subsets (Th1/Th2 and Th17/Treg) in the mesenteric lymph nodes were analyzed by flow cytometry. Network pharmacology and molecular docking were used to analyze the effect of diosmetin on PI3K/AKT pathway. Results Compared with TNBS group, diosmetin treatment significantly lowered DAI scores, histological scores, body weight loss and colon mucosal levels of TNF-α, IFN-γ, and IL-17A (P<0.05) and increased the colon length of the rat models, but these improvements did not reach the control levels (P<0.05). Diosmetin significantly lowered the percentages of Th1/Th17 cells in the mesenteric lymph nodes in TNBS-treated mice, which remained higher than the control levels (P<0.05); The percentages of Th2/Treg cells were significantly higher in diosmetin group than in TNBS group (P<0.05) and the control group (P<0.05). Network pharmacologic analysis identified 46 intersection targets of diosmetin and CD, and among them AKT1, EGFR, SRC, ESR1, MMP9 and PTGS2 were the top 6 core targets. GO and KEGG analyses showed that the PI3K/AKT signaling pathway was closely related with the therapeutic effect of diosmetin on CD-like colitis. Molecular docking suggested strong binding of diosmetin to the key core targets. Diosmetin significantly reduced the levels of p-PI3K and p-AKT in the colon mucosa in TNBS-treated mice (P<0.05), but their levels remained higher than those in the control group (P<0.05). Conclusion Diosmetin ameliorates TNBS-induced CDPlike colitis in mice possibly by regulating Th1/Th2 and Th17/Treg balance to improve intestinal immune disorder through inhibition of PI3K/AKT signaling.

Key words: Crohn's disease; colitis; diosmetin; intestinal mucosal immunity