Oxymatrine ameliorates ulcerative colitis via improving epithelial barrier function through targeting DSG2

Oxymatrine (OMT), an alkaloid isolated from Sophora flavescens Ait., is effective in treating ulcerative colitis (UC). However, its molecular mechanism of action remains unclear.

This research aimed to assess the therapeutic effects of OMT on chronic UC and to elucidate the underlying mechanisms.

The therapeutic effects of the water extract of the root of Sophora flavescens Ait. (WSF) and OMT were evaluated using a chronic UC mouse model. Proteomic analysis was conducted to elucidate the underlying mechanisms. Apoptosis models of HCT116 and Caco-2 cells, induced by TNF-α and IFN-γ were employed to assess the impact of OMT and its in vivo metabolite, matrine (MAT), on intestinal epithelial barrier (IEB) dysfunction. Cellular thermal shift assay (CETSA), drug affinity responsive target stability (DARTS), and microscale thermophoresis (MST) were used to evaluate the direct binding affinity of OMT to its targets. The target protein was knocked down via lentiviral transfection to further investigate the effects of OMT and MAT.

WSF and OMT alleviated chronic UC by inhibiting inflammation and improving IEB function. Proteomic analysis revealed that desmoglein-2 (Dsg2) was significantly upregulated. In an intestinal epithelial cell apoptosis model, OMT and MAT reduced Dsg2 cleavage, thereby enhancing cell adhesion and improving IEB function. OMT stabilized Dsg2 by directly binding to it. The therapeutic effects of OMT and MAT were diminished when Dsg2 was knocked down. Additionally, OMT and MAT inhibited caspase-8 activity, which was responsible for Dsg2 cleavage.

Dsg2 was identified as a target of OMT, contributing to its therapeutic benefits in UC. OMT therapy effectively inhibited Dsg2 cleavage by directly binding to it and suppressing caspase-8 activity, thereby enhancing IEB function.