Tryptanthrin Protects Mice against Dextran Sulfate Sodium-Induced Colitis through Inhibition of TNF-/NF-B and IL-6/STAT3 Pathways

Inflammatory bowel disease (IBD) is a notable health problem and may considerably affect the quality of human life. Previously, the protective roles of tryptanthrin (TRYP) against dextran sulfate sodium (DSS) induced colitis has been proved, but the concrete mechanism remained elusive. It has been suggested that TRYP could diminish the weight loss and improve the health conditions of mice with DSS induced colitis. Hematoxylin and eosin staining revealed that TRYP could improve the histopathological structure of the colon tissue. Two signaling pathways (TNF-/NF-Bp65 and IL-6/STAT3) were investigated using immunochemistry and western blot. The detected concentrations of the two cytokines TNF- and IL-6 showed that their levels decreased after TRYP treatment of the colitis. The protein expression level of NF-Bp65 in cytoplasm increased after TRYP treatment of the induced colitis. However, the protein level of NF-Bp65 in the nucleus decreased after administration of TRYP. The expression level of IB, the inhibitory protein of NF-Bp65, was tested and the results suggested that TRYP could inhibit the degradation of IB. The phosphorylation level of STAT3 was inhibited by TRYP and the expression level of STAT3 and p-STAT3 decreased after administration of TRYP. We conclude that TRYP improves the health condition of mice with DSS induced colitis by regulating the TNF-/NF-Bp65 and IL-6/STAT3 signaling pathways via inhibiting the degradation of IB and the phosphorylation of STAT3.