Cholesterol-Associated Locus EHBP1 Protects Against MASH Fibrosis
Excess cholesterol accumulation contributes to fibrogenesis in metabolic dysfunction-associated steatohepatitis (MASH, formerly known as nonalcoholic steatohepatitis [NASH]), but how hepatic cholesterol metabolism becomes dysregulated in MASH is not completely understood. We show here that human fibrotic MASH livers have decreased EHBP1, a novel GWAS locus associated with LDL cholesterol, and that the EHBP1 rs10496099 T>C variant in MASH patients is associated with decreased hepatic EHBP1 expression and with augmented MASH fibrosis. Congruent with the human data, EHBP1 loss- and gain-of-function increases and decreases MASH fibrosis in mice, respectively. Mechanistic studies reveal that EHBP1 promotes sortilin (SORT1)-mediated PCSK9 secretion, leading to LDLR degradation, decreased LDL uptake, and reduced TAZ, a fibrogenic effector. At a cellular level, EHBP1 deficiency affects intracellular localization of retromer, a protein complex required for sortilin stabilization. Our novel therapeutic approach to stabilizing retromer is effective in mitigating MASH fibrosis. Moreover, we show that the TNFa/PPARa pathway suppresses EHBP1 in MASH. These data not only provide new mechanistic insight into the role of EHBP1 in cholesterol metabolism and MASH fibrosis by uncovering the interaction between EHBP1 and other cholesterol-related loci, including SORT1, PCSK9, and LDLR, but also elucidate a novel interplay between inflammation and EHBP1-mediated cholesterol metabolism. Overall design: Total liver RNA from Chow, MASH, and shEhbp1 MASH mice was extracted for RNA-sequencing