Lianweng formula alleviates colonic inflammation through gut microbiota-mediated inactivation of the PTGS2/AKR1C3/ALOX5 pathway and subsequent suppression of arachidonic acid metabolism.

Abstract

BACKGROUND: Current clinical management of ulcerative colitis (UC) is often limited by inadequate efficacy and adverse effects. Our previous studies identified Lianweng formula (LW) as a promising therapeutic candidate and preliminarily elucidated its bioactive components. However, the integrated mechanism involving the interplay between gut microbiota and host metabolism remains obscure. PURPOSE: This study aimed to elucidate the regulatory mechanism of LW on arachidonic acid (AA) metabolism in UC rats, with a specific focus on the mediating role of gut microbiota. METHODS: The therapeutic efficacy of LW was first evaluated in a UC rat model by assessing inflammatory cytokines, histological injury, and mucosal barrier integrity. Integrated 16S rRNA sequencing and untargeted metabolomics were performed to map the alterations in gut microbiota and colonic metabolic profiles. Crucially, antibiotic cocktail (ABX) depletion and fecal microbiota transplantation (FMT) were employed to verify the causal role of gut microbiota in mediating LW's efficacy. Finally, targeted metabolomics was conducted to decipher the specific crosstalk between microbial composition and the AA metabolic pathway. RESULTS: Oral administration of LW significantly alleviated colonic pathological damage and restored intestinal barrier integrity, while effectively suppressing the inflammatory response in UC rats. Furthermore, LW effectively restored gut microbiota homeostasis by increasing the abundance of beneficial genera, such as g_Odoribacter and g_Rikenella, and decreasing the abundance of harmful genera, including g_Desulfovibrio and g_Paludicola, among others. Untargeted metabolomics highlighted the AA metabolic pathway as a critical target of LW, exhibiting strong correlations with the altered gut microbiota. Notably, gut microbiota depletion via ABX significantly compromised the therapeutic efficacy of LW and nullified its regulation of AA metabolism, identifying gut microbes as essential mediators. This causal link was further corroborated by FMT, which demonstrated that LW-modulated microbiota successfully recapitulated the suppression of AA metabolism and the therapeutic benefits. These findings were consistently validated by quantitative targeted metabolomics profiling. CONCLUSION: Our findings demonstrate that LW significantly mitigates colonic inflammation in UC rats, primarily by inhibiting the arachidonic acid metabolic pathway. Notably, this metabolic regulation and the consequent anti-inflammatory effects are critically dependent on LW-induced gut microbiota remodeling. This study offers novel therapeutic insights into UC treatment by highlighting the pivotal role of microbiota-metabolite crosstalk in the mechanism of action of LW.