title: Absence of receptor interacting protein kinase 3 prevents ethanol-induced liver injury.
abstract: Hepatocyte cell death via apoptosis and necrosis are major hallmarks of ethanol-induced liver injury. However, inhibition of apoptosis is not sufficient to prevent ethanol-induced hepatocyte injury or inflammation. Because receptor-interacting protein kinase (RIP) 3-mediated necroptosis, a nonapoptotic cell death pathway, is implicated in a variety of pathological conditions, we tested the hypothesis that ethanol-induced liver injury is RIP3-dependent and RIP1-independent. Increased expression of RIP3 was detected in livers of mice after chronic ethanol feeding, as well as in liver biopsies from patients with alcoholic liver disease. Chronic ethanol feeding failed to induce RIP3 in the livers of cytochrome P450 2E1 (CYP2E1)-deficient mice, indicating CYP2E1-mediated ethanol metabolism is critical for RIP3 expression in response to ethanol feeding. Mice lacking RIP3 were protected from ethanol-induced steatosis, hepatocyte injury, and expression of proinflammatory cytokines. In contrast, RIP1 expression in mouse liver remained unchanged following ethanol feeding, and inhibition of RIP1 kinase by necrostatin-1 did not attenuate ethanol-induced hepatocyte injury. Ethanol-induced apoptosis, assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling-positive nuclei and accumulation of cytokeratin-18 fragments in the liver, was independent of RIP3.
  
  
  CONCLUSIONS
  CYP2E1-dependent RIP3 expression induces hepatocyte necroptosis during ethanol feeding. Ethanol-induced hepatocyte injury is RIP3-dependent, but independent of RIP1 kinase activity; intervention of this pathway could be targeted as a potential therapeutic strategy.
authors: Departments of Pathobiology, Center for Liver Disease Research, Cleveland Clinic, Cleveland, OH, USA. roychos@ccf.org
authors: Sanjoy
authors: S
authors: Roychowdhury
authors: Megan R
authors: MR
authors: McMullen
authors: Sorana G
authors: SG
authors: Pisano
authors: Xiuli
authors: X
authors: Liu
authors: Laura E
authors: LE
authors: Nagy
mesh_terms: D000328:Adult; D000818:Animals; D017209:Apoptosis; D001706:Biopsy; D056486:Chemical and Drug Induced Liver Injury / Q000378:metabolism* / Q000517:prevention & control*; D019392:Cytochrome P-450 CYP2E1 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D000431:Ethanol / Q000009:adverse effects*; D005260:Female; D022781:Hepatocytes / Q000473:pathology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008108:Liver Diseases, Alcoholic / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008875:Middle Aged; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism
chemical_list: D007093:Imidazoles; D007211:Indoles; C507699:necrostatin-1; D000431:Ethanol; D019392:Cytochrome P-450 CYP2E1; C119705:RIPK3 protein, human; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C485615:Ripk3 protein, mouse