title: Inhibition of apoptosis protects mice from ethanol-mediated acceleration of early markers of CCl4 -induced fibrosis but not steatosis or inflammation.
abstract: BACKGROUND
  Correlative evidence indicates that apoptosis is associated with the progression of alcoholic liver disease. If apoptosis contributes to ethanol (EtOH)-induced steatohepatitis and/or fibrosis, then mice deficient in Bid, a key pro-apoptotic Bcl-2 family member, or mice treated with a pan-caspase inhibitor (VX166) should be resistant to EtOH-induced liver injury.
  
  
  METHODS
  This hypothesis was tested in mice using a model of chronic, heavy EtOH-induced liver injury, as well as in a model in which moderate EtOH feeding accelerated the appearance of early markers of hepatic fibrosis in response to acute carbon tetrachloride (CCl(4) ) exposure.
  
  
  RESULTS
  Chronic EtOH feeding to mice increased TUNEL- and cytokeratin-18-positive cells in the liver, as well as the expression of receptor-interacting protein kinase 3 (RIP3), a marker of necroptosis. In this model, Bid-/- mice or wild-type mice treated with VX166 were protected from EtOH-induced apoptosis, but not EtOH-induced RIP3 expression. Bid deficiency or inhibition of caspase activity did not protect mice from EtOH-induced increases in plasma alanine and aspartate amino transferase activity, steatosis, or mRNA expression of some inflammatory cytokines. Moderate EtOH feeding to mice enhanced the response of mice to acute CCl(4)  exposure, resulting in increased expression of α-smooth muscle actin and accumulation of extracellular matrix protein. VX166-treatment attenuated EtOH-mediated acceleration of these early indicators of CCl(4) -induced hepatic fibrosis, decreasing the expression of α-smooth muscle actin, and the accumulation of extracellular matrix protein.
  
  
  CONCLUSIONS
  EtOH-induced apoptosis of hepatocytes was mediated by Bid. Apoptosis played a critical role in the accelerating the appearance of early markers of CCl(4) -induced fibrosis by moderate EtOH but did not contribute to EtOH-induced hepatocyte injury, steatosis, or expression of mRNA for some inflammatory cytokines.
authors.affiliation: Center for Liver Disease Research, Departments of Pathobiology, Case Western Reserve University, Cleveland, Ohio, USA.
authors.forename: Sanjoy
authors.initials: S
authors.lastname: Roychowdhury
authors.forename: Dian J
authors.initials: DJ
authors.lastname: Chiang
authors.forename: Palash
authors.initials: P
authors.lastname: Mandal
authors.forename: Megan R
authors.initials: MR
authors.lastname: McMullen
authors.forename: Xiuli
authors.initials: X
authors.lastname: Liu
authors.forename: Jessica I
authors.initials: JI
authors.lastname: Cohen
authors.forename: John
authors.initials: J
authors.lastname: Pollard
authors.forename: Ariel E
authors.initials: AE
authors.lastname: Feldstein
authors.forename: Laura E
authors.initials: LE
authors.lastname: Nagy
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000172:deficiency*; D015415:Biomarkers / Q000378:metabolism; D002251:Carbon Tetrachloride / Q000633:toxicity*; D000431:Ethanol / Q000633:toxicity*; D005235:Fatty Liver, Alcoholic / Q000378:metabolism / Q000473:pathology* / Q000517:prevention & control; D005260:Female; D006519:Hepatitis, Alcoholic / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018836:Inflammation Mediators / Q000633:toxicity*; D008104:Liver Cirrhosis, Alcoholic / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D008108:Liver Diseases, Alcoholic / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout
chemical_list: D051023:BH3 Interacting Domain Death Agonist Protein; C494815:Bid protein, mouse; D015415:Biomarkers; D018836:Inflammation Mediators; D000431:Ethanol; D002251:Carbon Tetrachloride