Wumei Wan ameliorates ulcerative colitis in rats by modulating the inflammation-pyroptosis-intestinal stem cell axis.

Ethnopharmacological relevance: Ulcerative colitis (UC) is a chronic, relapsing inflammatory bowel disease primarily characterised by persistent disruption of the colonic epithelial barrier. Despite the proven clinical efficacy of the traditional Chinese medicine formulation Wumei Wan (WMW), its pharmacological mechanisms remain inadequately understood.

Aim of the study: This study aims to elucidate the therapeutic mechanisms through which WMW promotes the repair of colonic epithelial barrier damage in UC.

Methods: UC was induced in rats via dextran sulfate sodium (DSS), followed by treatment with low- and high-dose WMW or the positive control 5-ASA. Therapeutic effects of WMW on colonic barrier damage were assessed using conventional indices and serum biomarkers. Mechanistic insights were derived through network pharmacology analysis and transcriptome sequencing (RNA-seq), with experimental validation performed using reverse transcription quantitative PCR, Western blot analysis, and immunofluorescence (IF).

Results: Both high- and low-dose WMW improved serum biomarkers associated with intestinal barrier function (endotoxin, diamine oxidase, and D-lactate), alongside conventional metrics such as disease activity index, ZO-1, and MUC2 expression. Network pharmacology and RNA-seq analyses identified key therapeutic mechanisms, including modulation of pyroptosis, regeneration of LGR5⁺ intestinal stem cells (ISCs), and regulation of inflammatory signalling pathways. Experimental validation confirmed that WMW inhibited pyroptosis-associated proteins (NAIP5, NAIP6, NLRC4, GSDMD-N, caspase-1 p20, IL1β, and IL18) while promoting ISC regeneration via upregulation of LGR5, ASCL2, and IL11RA1, with co-localisation of LGR5 and IL11RA1-a novel finding. Additionally, WMW suppressed phosphorylation of JAK2/STAT3 pathway components (p-JAK2 and p-STAT3) and elements of the STING1/IRF3 pathway (p-STING1, p-IRF3, and p-NF-κB p65), offering moderate complementary regulation of inflammatory pathways in UC.

Conclusions: WMW mitigates UC-associated epithelial barrier dysfunction through a multifaceted mechanism involving inhibition of NAIP5/6-NLRC4 pathway-mediated epithelial pyroptosis, enhancement of ASCL2/IL11RA1-dependent LGR5⁺ ISC regeneration, and suppression of JAK-STAT and STING1/IRF3 inflammatory signalling. This polypharmacological action, driven by WMW's complex phytochemical composition, underscores therapeutic potential of multi-target herbal medicines in addressing the multifactorial pathogenesis of UC.