Autocrine Netrin-1 Signaling in Hepatic Stellate Cells Drives Liver Fibrosis and Diet-Induced Metabolic Dysfunction-Associated Steatohepatitis in Mice.

Liver fibrosis is a central feature of progressive liver diseases, including metabolic dysfunction-associated steatohepatitis (MASH). The profibrotic liver microenvironment drives hepatic stellate cell (HSC) activation and collagen deposition. However, the nature of HSC-mediated autocrine signaling during the fibrotic response has not been completely characterized. Here, we identify Netrin-1 as an autocrine factor that drives HSC activation and liver fibrosis in patients with MASH. Hepatic Netrin-1 expression was consistently elevated across multiple experimental models of liver fibrosis. Functional studies showed that adenovirus-associated virus (AAV)-mediated hepatic Netrin-1 overexpression exacerbated fibrosis, whereas HSC-specific conditional ablation of Netrin-1 markedly attenuated diet-induced MASH and CCl4-induced liver fibrosis. Notably, lipid nanoparticle-mediated siRNA knockdown of Netrin-1 ameliorated liver fibrosis in mice. Mechanistic investigations revealed that Netrin-1 promotes HSC activation through autocrine signaling mediated by the UNC5B receptor, which triggers rapid intracellular Ca(2+) mobilization and downstream SMAD2 phosphorylation and fibrogenic gene expression. Collectively, our findings identify a novel autocrine signaling axis in which HSC-derived Netrin-1 establishes a positive feedback loop that sustains HSC activation and drives fibrotic progression. Blocking the Netrin-1-mediated fibrogenic response may offer a potential therapeutic strategy for anti-fibrotic interventions.