Human milk fat substitutes improve obesity-related NAFLD by enriching LPC 18:2 to activate hepatic GPR119-AMPK signaling.

INTRODUCTION

Obesity-associated non-alcoholic fatty liver disease (NAFLD) remains a global health burden with limited treatment options. Human milk fat substitutes (HMFS), designed to mimic the triacylglycerol structure of breast milk, have shown potential metabolic benefits. However, the mechanisms underlying their effects on hepatic lipid metabolism remain unclear.

OBJECTIVES

This study aims to evaluate the therapeutic effects of HMFS on established high fat diet-induced metabolic dysfunction and to delineate the lipid-mediated pathways involved.

METHODS

A high-fat diet-induced obese mouse model was used to evaluate HMFS effects on metabolic parameters, liver histology, and lipid composition. Untargeted lipidomics identified candidate bioactive lipids. qPCR and Western blot were performed to assess hepatic gene and protein expression involved in lipid metabolism and signaling. Steatotic hepatocyte assays examined LPC 18:2 induced GPR119-AMPK activation. Molecular docking and molecular dynamics simulations were conducted to characterize LPC 18:2-GPR119 binding interactions.

RESULTS

HMFS significantly reduced weight gain, hepatic triacylglycerols, and serum dyslipidemia, and improved liver enzyme profiles. Lipidomics revealed a marked elevation of LPC 18:2 alongside broad triacylglycerol reduction. HMFS upregulated enzymes involved in triacylglycerol hydrolysis and phospholipid remodeling, restoring hepatic GPR119-AMPK activation and promoting fatty acid oxidation over lipogenesis. Spearman correlation analysis revealed that LPC 18:2 levels were inversely correlated with obesity markers and positively correlated with GPR119-AMPK signaling. In vitro, LPC 18:2 replicated these effects in hepatocytes, reducing steatosis and enhancing AMPK phosphorylation. Computational analyses demonstrated stable LPC 18:2-GPR119 binding with favorable interaction energies.

CONCLUSION

HMFS alleviates diet-induced metabolic impairments in mice by enriching LPC 18:2, which activates GPR119-AMPK signaling to promote hepatic lipid catabolism. These findings provide mechanistic evidence supporting structured lipids as potential nutritional interventions for obesity-related liver disease.