Absence of receptor interacting protein kinase 3 prevents ethanol-induced liver injury

Authors

  • Sanjoy Roychowdhury,

    Corresponding author
    1. Departments of Pathobiology, Center for Liver Disease Research, Cleveland Clinic, Cleveland, OH
    • Cleveland Clinic, Lerner Research Institute/NE40, 9500 Euclid Avenue, Cleveland, OH 44195
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    • fax: 216-636-1493

  • Megan R. McMullen,

    1. Departments of Pathobiology, Center for Liver Disease Research, Cleveland Clinic, Cleveland, OH
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  • Sorana G. Pisano,

    1. Departments of Pathobiology, Center for Liver Disease Research, Cleveland Clinic, Cleveland, OH
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  • Xiuli Liu,

    1. Departments of Anatomic Pathology, Center for Liver Disease Research, Cleveland Clinic, Cleveland, OH
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  • Laura E. Nagy

    1. Departments of Pathobiology, Center for Liver Disease Research, Cleveland Clinic, Cleveland, OH
    2. Departments of Gastroenterology, Center for Liver Disease Research, Cleveland Clinic, Cleveland, OH
    3. Department of Nutrition, Case Western Reserve University, Cleveland, OH
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  • Potential conflict of interest: Nothing to report.

  • Supported in part by ABMRF/The Foundation for Alcohol Research (S. R.) and grants RO1AA013868, P20 AA17069, from the National Institutes of Health and D.O.D. 10248754 (L. E. N.).

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. Conclusion: 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. (HEPATOLOGY 2013)

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