Demethylzeylasteral alleviates inflammation and colitis via dual suppression of NF-κB and STAT3/5 by targeting IKKα/β and JAK2.

Background: Ulcerative colitis (UC) is a common inflammatory bowel disease and a risk factor of colorectal cancer. Demethylzeylasteral (DZT), a bioactive component mainly isolated from Tripterygium wilfordii, has been shown to inhibit inflammation and cancer. However, its anti-UC function and molecular mechanisms have not been well characterized. This study aims to explore the therapeutic effect and functional targets of demethylzeylasteral against UC.

Methods: RT-qPCR, Western blot and ELISA were used to detect the generation of pro-inflammatory cytokines and chemokines in murine macrophage cells. Luciferase reporter gene, Western blot, pull-down, CETSA, DARTS, and virtual docking were employed to detect the anti-inflammatory targets and molecular mechanisms of demethylzeylasteral. The anti-inflammatory and anti-colitis effects of demethylzeylasteral were further determined in DSS-challenged mice.

Results: In vitro, demethylzeylasteral inhibited NO and PGE₂ production by suppressing the mRNA and protein expression of iNOS and COX-2, and suppressed the mRNA expression of TNF-α, IL-1β, IL-6, MCP-1, CXCL9, and CXCL10 in RAW264.7 macrophages stimulated by LPS/IFNγ. Furthermore, demethylzeylasteral was not only capable of inhibiting IKKα/β-NF-κB activation, but also able to block JAKs-STAT3/5 activation in LPS/INFγ-incubated RAW264.7 cells or DSS-exposed colon tissues of mice. Mechanistically, demethylzeylasteral was found to directly bind to IKKα/β and JAK2 kinases, leading to inactivation of pro-inflammatory signaling cascades and reduced generation of cytokines and chemokines. In vivo, oral administration of demethylzeylasteral significantly attenuated DSS-induced colitis, which was mainly manifested as mitigated symptoms of colitis, colonic mucosal barrier damage, and colonic inflammation.

Conclusion: We demonstrated that demethylzeylasteral alleviated UC pathology by blocking NF-κB and STAT3/5 pathways via targeting IKKα/β and JAK2 kinases, raising the possibility that demethylzeylasteral could act as a candidate for the treatment of UC.