Toxic lipid-induced epigenetic activation of ICAM1 in liver sinusoidal endothelium regulates myeloid-driven fibro-inflammatory response in MASH

BACKGROUND AND AIMS: Liver sinusoidal endothelial cells (LSECs) acquire a proinflammatory phenotype in metabolic dysfunction-associated steatohepatitis (MASH), characterized by enhanced expression of adhesion molecules and inflammatory mediators, a process termed lipotoxic endotheliopathy. However, the molecular drivers of this transformation remain incompletely defined. APPROACH AND RESULTS: We employed complementary models of lipotoxicity and MASH, including palmitate-treated primary human LSECs (in vitro), cultured precision-cut liver slices (PCLS) from MASH mice and normal human liver treated with MASH-inducing media (ex vivo), and diet-induced MASH models (in vivo). GeoMx digital spatial profiling of human MASH livers revealed enriched proinflammatory and fibrogenic signaling between LSECs and myeloid cells. Among the top upregulated genes and ligand-receptor pairs was ICAM1, whose expression correlated with disease severity and was increased in human MASH by immunostaining. ATAC-seq on primary mouse LSECs showed enhanced chromatin accessibility at the Icam1 promoter in MASH. Chromatin immunoprecipitation confirmed enrichment of the active epigenetic mark H3K27ac and BRD4 binding at the ICAM1 promoter in human LSECs under lipotoxic stress. Mechanistically, we identified the GSK3β/c-Jun/BRD4 axis as a key regulator of ICAM1 induction in LSECs. In vivo, ICAM1-neutralizing antibody or endothelial-specific epigenetic suppression reduced hepatic inflammation, injury, and fibrosis in MASH mice. CONCLUSIONS: ICAM1 is epigenetically upregulated in LSECs during lipotoxic stress and promotes myeloid cell recruitment in MASH. Targeting the epigenetic regulation of ICAM1 may offer a novel therapeutic strategy for treating human MASH.