Hepatocyte Hedgehog activation attenuates acetaminophen-induced liver injury through a Vegfa-associated vascular response

Abstract Acetaminophen (APAP) overdose is the leading cause of drug-induced acute liver failure, yet early pathways linking hepatocellular stress to tissue integrity remain incompletely defined. Here, we demonstrate that canonical Hh signaling is rapidly activated in centrilobular hepatocytes upon APAP challenge, preceding significant inflammation and recovery. Using mice with hepatocyte-specific constitutive expression of Smoothened (SmoM2), we show that pre-activation of Hh signaling attenuates APAP-induced liver injury and immune cell infiltration. Functionally, this protection is independent of intracellular glutathione depletion or CYP2E1-mediated APAP metabolism. Instead, we identify a Vegfa-associated vascular/endothelial response, in which hepatocyte Smo activation increases vascular endothelial growth factor A (VEGFA) expression and is linked to improved vascular injury and barrier function, as well as reduced expression of adhesion molecules (ICAM-1 and E-selectin). Furthermore, sorafenib treatment and AAV8-mediated hepatic Vegfa knockdown attenuated the protective phenotype in SmoM2 mice. Collectively, our findings support a model in which hepatocyte Smo activation is associated with a Vegfa-dependent vascular/endothelial protective response, suggesting a potential vascular-focused direction for studying acute liver failure.