Mechanism of zingerone alleviating colitis induced by dextran sodium sulfate in mice

Abstract

Objective To investigate the efficacy of zingerone (Zin) on dextran sodium sulfate (DSS)-induced colitis in mice and its potential immunomodulatory mechanism. Methods SPF C57BL/6 male mice aged 6 to 8 weeks were divided into control group (Water), model group (DSS), and Zin intervention group (DSS+Zin), with 5 mice in each group. Acute ulcerative colitis model was constructed using DSS solution, and the changes in body weight, disease activity index (DAI), colon length, and histopathological scores were compared among the groups. RT-qPCR and corresponding reagents and kits were employed to detect the mRNA and protein expression of inflammatory cytokines in the colonic tissue, respectively. The effects of Zin on T cell subsets and on the expression of transcription factor RORγt were determined by flow cytometry in vitro and in vivo. Moreover, the transcriptional activity of RORγt and activity of Rorc promoter were examined using dual-luciferase reporter system. Results As compared with the control group, the mice in the DSS group showed shorter colon length, higher scores of DAI and histopathological index (P < 0.05), with increased mRNA levels of IL-17A, IL-21, IL-22, IL-6, IL-1 β and IFN-γ (P < 0.05), while decreased mRNA level of TGF-β(P < 0.05). The protein levels of IL-17A, IL-17F, IL-22, and IFN-γ were also upregulated in the DSS group (P < 0.05). However, Zin treatment significantly relieved the above clinical symptoms and reversed the expression of above inflammatory factors (P < 0.05). Flow cytometry indicated that Zin inhibited the differentiation of Th17 cells and the expression of RORγt, and promoted the differentiation of Treg cells both in vitro and in vivo (P < 0.05), but the differentiation of Th1 subset was not affected. The dual-luciferase reporter assay demonstrated that the transcriptional activity of RORγt and Rorc promoter activity were remarkably suppressed after Zin treatment (P < 0.05). Conclusion Zin alleviates DSS-induced colitis in mice by regulating the balance of Th17/Treg cells and inhibiting RORγt expression.

Keywords

• zingerone
• ulcerative colitis
• th17 cells
• treg cells
• rorγt
• intestinal immunity