Gan-Jiang-Ling-Zhu Decoction Prevents Paigen's Diet-induced Lean Metabolic Dysfunction-associated Steatotic Liver disease by Regulating Bile Acid Metabolism.

Introduction: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a global health concern, even among lean individuals. The Gan-Jiang-Ling-Zhu decoction (GZD), a traditional Chinese medicine formula, shows therapeutic potential against MASLD. This study investigated the efficacy of GZD in lean MASLD and explored its mechanisms of action.

Methods: A lean MASLD mouse model was established using C57BL/6 mice fed with a cholesterol- rich Paigen's diet (PD). Following successful modeling, mice were administered GZD (1.8, 3.6, or 7.2 g/kg) or vehicle control. Body weight, food intake, and liver weight were monitored. Hepatic steatosis and lipid accumulation were assessed via H&E and Oil Red O staining, while serum enzymes were quantified biochemically. Gut microbiota composition was analyzed by 16S rRNA gene sequencing, and bile acid (BA) profiles in feces and serum were measured using UPLC-TQMS.

Results: Twelve weeks of PD feeding induced a lean MASLD phenotype characterized by reduced body weight alongside hepatic steatosis and dyslipidemia. The GZD treatment dosedependently ameliorated liver steatosis and lipid accumulation, with the highest dose (7.2 g/kg) showing superior efficacy. GZD restored gut microbiota balance by reducing pathogenic bacteria and enriching taxa involved in BA metabolism, leading to increased fecal excretion of secondary BAs. Conversely, serum levels of secondary BAs were significantly reduced after GZD treatment.

Discussion: Our study highlights the promising role of GZD in lean MASLD, the involvement of gut microbiota and related BA metabolism that aligns with emerging evidence that gut dysbiosis and disrupted BA homeostasis are central to MASLD pathogenesis, even in lean individuals. However, the mechanistic links between specific microbial changes, BA pool composition, and hepatic outcomes remain to be elucidated.

Conclusion: GZD ameliorates hepatic steatosis in lean MASLD mice, an effect associated with modulation of gut microbiota composition and increased fecal excretion of secondary BAs. These findings suggest the potential of GZD as a therapeutic option for lean MASLD through gutliver axis regulation.