Yinzhihuang formula modulates the microbe‒gut‒liver axis and bile acid excretion to attenuate cholestatic liver injury

Background: Cholestatic liver injury is a hepatobiliary disorder primarily characterized by cholestasis, which significantly contributes to liver damage. The Yinzhihuang (YZH) oral preparation is an effective clinical treatment for cholestatic liver injury; however, the specific mechanism of action has not been clarified.

Purpose: This study investigated YZH's pharmacological mechanisms associated with the microbe‒gut‒liver axis in cholestatic mice, offering new perspectives for the treatment of cholestasis.

Methods: YZH's protective effects were evaluated by evaluating serum liver injury indices and liver staining in an alpha-nephthyl isothiocyanate (ANIT)-induced intrahepatic cholestasis mouse model. Colon hematoxylin‒eosin (H&E) and alcian blue staining and FITC‒dextran leakage assays were performed to assess intestinal barrier integrity. Fluorescence in situ hybridization was employed to analyze bacterial translocation. Additionally, 16S rRNA sequencing, fecal microbiota transplantation, and bile acid metabolomics analysis were conducted to examine the relationships among the microbiome, bile acid metabolism, and YZH formula.

Results: We found that YZH administration alleviated symptoms of ANIT-induced hepatic pathological injury and fibrosis. In addition, YZH reduced the transfer of gut bacteria to liver tissue by maintaining an intact intestinal barrier. Notably, YZH influenced the intestinal microbiota composition, upregulated the abundance of bile acid metabolism-associated probiotic bacteria, including Clostridiales, Lachnospiraceae and Bifidobacterium pseudolongum; and downregulated the abundance of Escherichia-Shigella and Serratia, thereby promoting bile acid excretion.

Conclusion: YZH protects against cholestatic liver damage by promoting bile excretion and maintaining intestinal mucosal barrier integrity. Furthermore, YZH alleviates cholestasis in a gut microbiota-dependent manner, and upregulation of probiotics may be crucial for YZH's influence on bile acid metabolism.