Sishen Pill & Tongxieyaofang ameliorated ulcerative colitis through the activation of HIF-1α acetylation by gut microbiota-derived propionate and butyrate.

Background: Ulcerative colitis (UC) is a chronic inflammatory bowel disease closely related to gut microbiota dysbiosis and intestinal homeostasis imbalance. Sishen Pill&Tongxieyaofang (SSP-TXYF) has a long history of application in traditional Chinese medicine and is widely used in UC clinics. However, its mechanism of action is still unclear.

Purpose: This study aimed to explore the potential regulatory role of SSP-TXYF in protecting against UC through metabolites produced by the intestinal microbiota, and elucidate its underlying molecular mechanism.

Study Design And Methods: 16S rRNA and UPLC-QE-Orbitrap-MS were used to assess the microbiota and short-chain fatty acids (SCFAs). A rat model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced gut microbiota dysbiosis was used to study the effects of SSP-TXYF on UC in vivo. Intestinal epithelial cells-6 (IEC-6) were treated with lipopolysaccharide (LPS). The intestinal mucosal barrier (IMB) functions were investigated by alcian blue staining and western blot analysis. The mechanism of SSP-TXYF influenced the HIF-1α acetylation pathway was examined by real-time fluorescence quantitative PCR (qPCR), Western blotting, and Co-immunoprecipitation.

Results: Using 16S rRNA gene-based microbiota analysis, we found that SSP-TXYF ameliorated TNBS-induced gut microbiota dysbiosis. We found that SSP-TXYF significantly inhibited the decreased abundance of Firmicutes in UC rats, in addition, the abundance of Actinobacteria was also improved. The mechanism of SSP-TXYF-treated TNBS-induced UC resulted from improved IMB functions via the activation of hypoxia-inducible factor-1 (HIF-1α) acetylation. Notably, SSP-TXYF Enriched microbiota-derived metabolites propionate and butyrate, which could activate HIF-1α acetylation in IEC. Furthermore, exogenous treatment of propionate and butyrate reproduced similar protective effects as SSP-TXYF to UC through improving HIF-1α-dependent IMB functions.

Conclusions: Overall, our findings suggest that the gut microbiota-propionate/butyrate-HIF-1α-IMB axis plays an important role in SSP-TXYF-maintaining intestinal homeostasis, which may represent a novel approach for UC prevention via the intervention of any link in this axis.