Coptisine activates aryl hydrocarbon receptor to regulate colonic epithelial homeostasis in DSS induced ulcerative colitis and TNF-α challenged intestinal organoids

Background

Coptisine is a bioactive isoquinoline alkaloid derived from Coptis Chinensis, exhibiting significant pharmacological potential. Emerging evidence suggests its therapeutic efficacy in gastrointestinal disorders through modulating inflammation and maintaining gut homeostasis.

Purpose

The study aimed to elucidate the molecular mechanisms underlying coptisine mediated restoration of intestinal barrier integrity in ulcerative colitis (UC) and TNF-α challenged intestinal organoids.

Methods

A murine UC model was established by dextran sulfate sodium (DSS) induction to evaluate coptisine's therapeutic effects on colonic inflammation and mucosal barrier dysfunction. Complementary in vitro investigations were conducted using TNF-α-challenged HT-29 cells and intestinal organoids derived from wild-type mice to assess epithelial barrier repair capabilities. Additionally, we utilized an integrated experimental approach incorporating cellular thermal shift assay, luciferase reporter assays to explore the influence of coptisine on AhR activation. Lastly, specific AhR dependency of coptisine on barrier protective effects were further validated through three independent model systems: shAhR-transfected HT-29 cells, AhR KO murine intestinal organoids, and AhR KO mice subjected to DSS challenge.

Results

Coptisine administration significantly attenuated colitis severity in DSS-treated mice, evidenced by reduced histopathological scores, decreased colonic inflammation, and enhanced gut barrier integrity through upregulation of tight junction proteins (TJ proteins). In a barrier dysfunction model of TNF-α stimulation in HT-29 cells and intestinal organoids, coptisine treatment effectively normalized the expression levels of TJ proteins. Mechanistically, coptisine exhibited potent AhR activation through increased nuclear translocation and transcriptional regulation of CYP1A1. Coptisine dose-dependently inhibited reactive oxygen species (ROS) production and NF-κB activation in TNF-α treated HT-29 cells. Crucially, AhR knockdown or knockout completely abolished coptisine's inhibitory effects on NF-κB activation and the protective efficacy in barrier function, confirming pathway dependency.

Conclusion

Coptisine ameliorates intestinal barrier dysfunction and improves UC related symptom in an AhR-dependent manner. This mechanistic insight positions coptisine as a promising phytochemical candidate for UC therapy.