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Inhibition of Apoptosis Protects Mice from Ethanol‐Mediated Acceleration of Early Markers of CC l 4 ‐Induced Fibrosis but not Steatosis or Inflammation
Author(s) -
Roychowdhury Sanjoy,
Chiang Dian J.,
Mandal Palash,
McMullen Megan R.,
Liu Xiuli,
Cohen Jessica I.,
Pollard John,
Feldstein Ariel E.,
Nagy Laura E.
Publication year - 2012
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.2011.01720.x
Subject(s) - apoptosis , steatosis , fibrosis , endocrinology , liver injury , medicine , tunel assay , inflammation , steatohepatitis , ccl4 , chemistry , carbon tetrachloride , biology , fatty liver , biochemistry , disease , organic chemistry
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 B id, a key pro‐apoptotic B cl‐2 family member, or mice treated with a pan‐caspase inhibitor ( VX 166) 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 ( RIP 3), a marker of necroptosis. In this model, B id−/− mice or wild‐type mice treated with VX 166 were protected from EtOH ‐induced apoptosis, but not EtOH ‐induced RIP 3 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. VX 166‐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 B id. 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.