Diosmin alleviates colitis by inhibiting PANoptosis of intestinal epithelial cells and regulating gut microbiota and metabolites.

Background: Inflammatory bowel disease (IBD), particularly ulcerative colitis (UC), is a chronic inflammatory disorder characterized by an unclear etiology, often linked to gut microbiota dysbiosis and immune dysregulation. Existing UC therapies are constrained by suboptimal efficacy and adverse effects, underscoring the necessity for novel therapeutic strategies. Diosmin (DIO), a naturally occurring flavonoid, has demonstrated anti-inflammatory and antioxidant potential, yet its precise mechanisms and therapeutic role in colitis remain poorly understood.

Purpose: This study aimed to investigate the therapeutic efficacy and mechanistic underpinnings of DIO in dextran sulfate sodium (DSS)-induced colitis, with a focus on its effects on intestinal epithelial cell PANoptosis, gut microbiota composition, fecal metabolites, and an in vitro inflammatory model using human colonic epithelial cells.

Study Design: A controlled experimental design was employed, utilizing a DSS-induced murine colitis model and an LPS-induced inflammatory model in human colonic epithelial cells (NCM460). Mice were allocated into four groups: normal control, DSS-induced colitis, low-dose DIO (DIO-L, 100 mg/kg), and high-dose DIO (DIO-H, 200 mg/kg). In vitro experiments involved treating NCM460 cells with varying DIO concentrations post-LPS stimulation to assess its impact on inflammation and epithelial barrier integrity.

Methods: Mice were administered DIO orally at 100 mg/kg or 200 mg/kg daily. Therapeutic outcomes were evaluated through body weight monitoring, Disease Activity Index (DAI) scoring, and histopathological examination. Gut microbiota composition was analyzed via 16S rRNA sequencing, while untargeted metabolomics was employed to profile fecal metabolites. Data integration was performed using O2PLS and WGCNA to identify microbiota-metabolite correlations. In vitro, immunofluorescence staining and Western blotting were utilized to evaluate the expression of tight junction proteins (ZO-1, E-cadherin, and Occludin).

Results: DIO administration significantly ameliorated colitis symptoms in mice, as evidenced by attenuated weight loss, reduced DAI scores, and preserved colon length. Histopathological analysis confirmed diminished inflammation and tissue damage in DIO-treated groups. Mechanistically, DIO suppressed the expression of PANoptosis-associated genes and proteins, including ZBP1 and Caspase-1, while maintaining epithelial barrier integrity in vitro. Furthermore, DIO modulated gut microbiota composition, promoting beneficial taxa such as Ruminococcus and reducing pathogenic Proteobacteria. Metabolomic profiling revealed alterations in key metabolic pathways, including flavonoid and steroid hormone biosynthesis, which correlated with microbiota changes.

Conclusion: DIO effectively mitigates DSS-induced colitis by inhibiting intestinal epithelial cell PANoptosis, preserving barrier function, and modulating gut microbiota and metabolite profiles. These findings highlight DIO's potential as a therapeutic agent for IBD and warrant further exploration of its clinical applications.