Protective effects of Brassica rapa L. water extract against DSS-induced acute UC-like colitis in mice and its regulatory mechanisms involving gut microbiota and the intestinal mucosal barrier.

INTRODUCTION

The present study aimed to evaluate the protective effects of Brassica rapa L. (Br) water extract against dextran sulfate sodium (DSS)-induced acute ulcerative colitis (UC)-like injury in mice and to explore the underlying mechanisms.

METHODS

A DSS-induced acute UC-like colitis mouse model was established to assess the effects of Br administration. Disease severity was evaluated based on body weight loss, disease activity index (DAI) scores, colon length, colon weight, intestinal barrier integrity, and histopathological changes using H&E staining. Inflammatory mediators, TLR4/TLR9 expression, tight junction (TJ) proteins, gut microbiota composition by 16S rRNA sequencing, and intestinal metabolic profiles by UPLC-MS/MS-based non-targeted metabolomics were also analyzed.

RESULTS

Br administration significantly ameliorated disease severity, as evidenced by mitigated body weight loss, reduced disease activity index (DAI) scores, attenuated colon shortening, normalized colon weight, and improved intestinal barrier integrity. Histopathological analysis (H&E) demonstrated that Br alleviated colonic tissue damage and inflammatory cell infiltration. The treatment also decreased the levels of proinflammatory mediators (IL-6, MPO, CXCL-1, and TNF-α) and downregulated the colonic expression of TLR4 and TLR9, while upregulating the expression of tight junction (TJ) proteins Occludin (OCC) and ZO-1. Furthermore, 16S rRNA sequencing revealed that Br restored gut microbial diversity and composition, specifically enriching potentially beneficial genera such as Alloprevotella, Lachnospiraceae_unclassified, and Alistipes, while suppressing the expansion of genera such as HT002. UPLC-MS/MS-based non-targeted metabolomic analysis suggested that Br was associated with the modulation of intestinal metabolic profiles, including changes in several putatively annotated metabolite features such as 12-Hydroxy-12-octadecanoylcarnitine and Vanillin.

DISCUSSION: Br water extract alleviates DSS-induced acute UC-like colitis injury in mice, possibly by attenuating inflammatory responses, downregulating abnormal TLR4/TLR9 expression, improving intestinal mucosal barrier function, and modulating gut microbiota composition and associated metabolic profiles.