Small extracellular vesicles derived from lipotoxic hepatocytes transport FASN to promote hepatic stellate cell activation.

Abstract

OBJECTIVE: Metabolic dysfunction-associated steatotic liver disease (MASLD) is the leading cause of chronic liver disease worldwide, with the progression of its fibrosis serving as a critical determinant of patient prognosis. This study aims to elucidate the molecular mechanisms by which lipidotoxic hepatocyte-derived small extracellular vesicles (LTH-sEV) promote the activation of hepatic stellate cells (HSCs) and the progression of MASLD-associated liver fibrosis through the transport of fatty acid synthase (FASN). APPROACH AND RESULTS: The biological characteristics of LTH-sEV were characterized using nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and western blot. In vitro experiments demonstrated that treatment with LTH-sEV significantly increased levels of reactive oxygen species (ROS), decreased glutathione (GSH) content, elevated malondialdehyde (MDA) levels, and upregulated the expression of α-smooth muscle actin (α-SMA) and collagen (COL1A1, COL3A1) in HSCs. Liquid chromatography-mass spectrometry (LC-MS) analysis identified significant enrichment of FASN protein in LTH-sEV. Gene editing experiments demonstrated that FASN overexpression exacerbated the pro-fibrotic effects of LTH-sEV, while FASN knockdown reversed these effects. Animal experiments revealed that LTH-sEV injection significantly increased the area of liver fibrosis in high-fat diet (HFD) mice, and FASN knockdown or inhibitor reversed the effects of LTH-sEV. CONCLUSION: This study reveals the molecular mechanism through which LTH-sEV exacerbate oxidative stress in HSCs via FASN transport, providing a theoretical basis for developing anti-fibrotic strategies targeting the sEV-FASN axis. Future research could further explore the clinical translational value of FASN inhibition-based precision therapy in MASLD.