Lipid nanoparticle-delivered ornithine transcarbamylase mRNA alleviates liver fibrosis in preclinical models

BACKGROUND AND AIMS: Liver fibrosis poses a major health threat globally, with an acute shortage of effective treatments to stop or reverse its progression. Hepatocyte injury serves as the primary cause of liver fibrosis, and restoring the expression of damaged proteins via mRNA delivery represents a promising therapeutic strategy. Clinical studies and animal models have demonstrated that mitochondrial ornithine transcarbamylase ( OTC ) deficiency correlates with increased incidence of liver fibrosis. In this study, we examined the therapeutic potential of OTC mRNA delivery for liver fibrosis. APPROACH AND RESULTS: Analysis of OTC expression and distribution in liver fibrosis revealed significant downregulation in fibrotic tissues. Restoring OTC expression in hepatocytes through AAV8-TBG-OTC significantly inhibits the progression of liver fibrosis. OTC mRNA sequences were developed using a codon-optimization artificial intelligence (AI) tool and synthesized with N1-methylpseudouridine modification, followed by encapsulation into lipid nanoparticle (LNP). Repeated in vivo delivery of OTC mRNA-LNP induced a robust inhibition of fibrogenesis in multiple mouse liver fibrosis models. Mechanistically, restoring OTC mRNA expression significantly recovers impaired mitochondrial and hepatocyte functions, while concurrently inhibiting paracrine ammonia-induced activation of HSCs and macrophages. OTC mRNA significantly suppresses collagen deposition, while the THR- β agonist Resmetirom potently inhibits lipid accumulation; the combination exhibits potent complementary efficacy against metabolic dysfunction-associated steatohepatitis (MASH) liver fibrosis. CONCLUSIONS: Collectively, our study provides the first direct preclinical evidence supporting OTC mRNA therapeutics for treating liver fibrosis and establishes proof-of-concept for mRNA therapy as a novel strategy to reverse liver fibrosis.