Hyodeoxycholic Acid Reduces Hepatic Steatosis Through Dual GLP-1 and Immune Pathways: Cell Reports | August 2026

Introduction:

Bile acids are increasingly recognised as metabolic signalling molecules rather than simply mediators of digestion. This experimental study investigated hyodeoxycholic acid (HDCA) and identified two complementary pathways through which it reduces hepatic fat accumulation, converging on PPARα-mediated fatty acid oxidation.

Why was this study needed?

Hepatic steatosis is the earliest stage of MASLD and can progress to MASH and fibrosis.

Bile acids can regulate metabolism, immunity, and incretin secretion.

The mechanisms underlying the anti-steatotic effects of HDCA were unclear.

Understanding bile acid–GLP-1–immune interactions could reveal novel therapeutic targets for MASLD.

Results:

HDCA significantly reduced hepatic steatosis in high-fat diet-fed mice, but this benefit disappeared when PPARα was absent.

HDCA activated two distinct pathways: increased GLP-1 signaling and activation of hepatic iNKT cells with IFN-γ production.

Both pathways converged on PPARα, increasing hepatic fatty acid oxidation and reducing triglyceride accumulation.

Loss of either GLP-1 receptor signalling or iNKT cells impaired HDCA's anti-steatotic effect, confirming their mechanistic importance.

Clinical Impact:

This study reveals an intriguing gut–immune–liver metabolic axis in which a bile acid simultaneously engages incretin and immune pathways to reduce hepatic steatosis. HDCA could therefore represent a novel multi-target strategy for MASLD. However, these findings are preclinical, and efficacy and safety in humans remain unknown.

Bottom Line:

Hyodeoxycholic acid reduces hepatic steatosis through two complementary pathways—GLP-1 signalling and iNKT cell/IFN-γ activation—both converging on PPARα-driven fatty acid oxidation. The findings identify HDCA as an interesting potential metabolic therapy for MASLD that now requires human validation.