OR21-07 Liver lipid droplet cholesterol content is a key determinant of metabolic dysfunction-associated steatohepatitis

Abstract Disclosure: I. Sakuma: None. R.C. Gaspar: None. Y. Taki: None. M. Perelis: None. M.W. Roden: None. T. Tanaka: None. G.I. Shulman: None. Context: Metabolic dysfunction-associated steatohepatitis (MASH) represents a progressive form of steatotic liver disease which increases the risk for fibrosis and advanced liver disease. The FDA recently approved resmetirom, a liver-directed β-selective thyroid hormone receptor agonist, for MASH with significant fibrosis. However, only 29% of Phase III trial participants responded, demonstrating the need for additional new therapeutic targets for MASH. The accumulation of discrete species of bioactive lipids has been postulated to activate signaling pathways that promote inflammation and fibrosis. However, the key pathogenic lipid remains debated. Hypothesis: We hypothesized that cholesterol in liver lipid droplets plays a key role in MASH development. Methods and Results: We explored candidates using various dietary, molecular, and genetic models. C57BL/6 mice fed a choline-deficient L-amino acid-defined high-fat diet (CDAHFD) developed steatohepatitis and increased gene expression of liver fibrosis markers (Col1a1, αSMA) within five days, associated with increased cholesterol accumulation in liver lipid droplets but no change in total liver cholesterol content. Treating mice with antisense oligonucleotides (ASOs) against Coenzyme A synthase (Cosay), Cell Death-inducing DNA fragmentation factor-like effector B (CideB), hydroxysteroid 17-beta dehydrogenase 13 (Hsd17b13) or treatment with bempedoic acid or atorvastatin decreased liver lipid droplet cholesterol content and prevented CDAHFD-induced MASH and the fibrotic response. All these salutary effects were abrogated with dietary cholesterol supplementation. To further validate the role of liver lipid droplet cholesterol in human MASH, we analyzed metabolites in lipid droplets from human liver samples. Our analysis revealed that cholesterol in liver lipid droplets was higher in individuals with MASH and liver fibrosis compared to those in other groups (no metabolic dysfunction-associated steatotic liver [MASL], MASL, and MASH without fibrosis). Furthermore, cholesterol levels in liver lipid droplets were higher in carriers of the PNPLA3 I148M variant (rs738409) than in those with HSD17B13 variants (rs72613567). Conclusions: Our findings identify cholesterol in liver lipid droplets as a critical mediator of MASH and demonstrate that COASY, CIDEB, HSD17B13 knockdown and bempedoic acid are novel therapeutic approaches to reduce liver lipid droplet cholesterol content and thereby prevent the development of MASH and liver fibrosis. In addition, this mechanism broadly links to human MASH pathogenesis and is associated with gene variants, including PNPLA3 and HSD17B13. Presentation: Saturday, July 12, 2025