Mature Adipocyte‐Derived Extracellular Vesicles Activate Hepatic Stellate Cells and Promote Liver Fibrosis via Inflammation

BACKGROUND AND AIMS: Extracellular vesicles (EVs) play a crucial role in intercellular communication, particularly in metabolic regulation and liver disease. This study aimed to investigate the differential effects of EVs derived from pre-adipocytes (PA) and mature adipocytes (MA) on hepatic stellate cell (HSC) activation in vitro and their role in promoting liver fibrosis in high-fat diet (HFD)-fed mice. METHODS: EVs were isolated from PA and MA following transdifferentiation, which was confirmed by assessing adipogenic markers (PPAR-γ, perilipin, adiponectin, leptin, and Glut4). EVs were characterized by size and CD9 expression. LX-2 cells were treated with PA- or MA-derived EVs to assess fibrotic and inflammatory gene expression. In vivo, C57BL/6 mice on HFD were administered PA-EVs or MA-EVs to evaluate liver pathology. RESULTS: MA-EVs exhibited a distinct transcriptomic profile and significantly upregulated fibrotic (α-SMA, COL1A1) and inflammatory markers in LX-2 cells, indicating HSC activation. Conversely, PA-EVs had minimal effects. In HFD-fed mice, MA-EVs injection led to pronounced liver damage, including steatosis, inflammation, and fibrosis, compared with mice receiving PA-EVs, which showed no major pathological changes. CONCLUSIONS: MA-EVs aggravate liver fibrosis and inflammation both in vitro and In vivo, while PA-EVs appear to have relatively limited effects. These findings highlight the functional heterogeneity of adipocyte-derived EVs and suggest MA-EVs as potential contributors to the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD). Targeting specific EV subpopulations may present novel therapeutic strategy for MASLD.