Hepatocyte RIPK1 scaffolding function protects against alcohol-induced liver injury by restraining ER stress-driven apoptosis and inflammation

While RIPK1 kinase activity has been implicated in various pathologies, the role of its scaffolding function in the liver, particularly in ALD, is unknown. Here, using hepatocyte-specific RIPK1 knockout (Ripk1-hepKO) mice, we demonstrate that loss of RIPK1 markedly aggravates ethanol-induced liver injury. In both chronic and acute-binge ethanol feeding models, Ripk1-hepKO mice exhibited significantly elevated serum transaminases, enhanced hepatocyte apoptosis, and amplified hepatic inflammation with increased macrophage infiltration, without a change in steatosis. Transcriptomic analysis revealed enrichment of inflammatory pathways in Ripk1-hepKO livers. Mechanistically, we identified endoplasmic reticulum (ER) stress as a critical contributor to this phenotype. RIPK1 deficiency was associated with attenuated NF-κB/p65 signaling, preferential amplification of eIF2α-ATF4-CHOP-associated stress responses, and enhanced CHOP accumulation, while pharmacological modulation of ER stress-associated pathways using 4-phenylbutyrate (4-PBA) or ISRIB ameliorated hepatocyte apoptosis, liver injury, and inflammation in ethanol-fed Ripk1-hepKO mice. Translating these findings to human disease, liver specimens from ALD patients showed elevated hepatocyte apoptosis, CD68+ macrophage infiltration, and induction of ER stress markers. Our study unveils a previously unrecognized protective role for the scaffold function of hepatocyte RIPK1 in ALD, positioning RIPK1 scaffolding and ER stress-associated signaling as promising therapeutic targets for ALD.