Biochemistry, Pharmacology, Physiology and Metabolism
Inhibition of Apoptosis Protects Mice from Ethanol-Mediated Acceleration of Early Markers of CCl4-Induced Fibrosis but not Steatosis or Inflammation
Article first published online: 24 JAN 2012
Copyright © 2012 by the Research Society on Alcoholism
Alcoholism: Clinical and Experimental Research
Volume 36, Issue 7, pages 1139–1147, July 2012
How to Cite
Roychowdhury, S., Chiang, D. J., Mandal, P., McMullen, M. R., Liu, X., Cohen, J. I., Pollard, J., Feldstein, A. E. and Nagy, L. E. (2012), Inhibition of Apoptosis Protects Mice from Ethanol-Mediated Acceleration of Early Markers of CCl4-Induced Fibrosis but not Steatosis or Inflammation. Alcoholism: Clinical and Experimental Research, 36: 1139–1147. doi: 10.1111/j.1530-0277.2011.01720.x
- Issue published online: 10 JUL 2012
- Article first published online: 24 JAN 2012
- Manuscript Accepted: 31 OCT 2011
- Manuscript Received: 17 MAY 2011
- ABMRF/The Foundation for Alcohol Research
- NIH grant. Grant Numbers: RO1AA013868, P20 AA17069, DOD #10248754
- American Liver Foundation fellowship. Grant Numbers: P20 AA17069 #6017, R01 DK076852
- Alcoholic Liver Disease;
- Cell Death;
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.
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 (CCl4) exposure.
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 CCl4 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 CCl4-induced hepatic fibrosis, decreasing the expression of α-smooth muscle actin, and the accumulation of extracellular matrix protein.
EtOH-induced apoptosis of hepatocytes was mediated by Bid. Apoptosis played a critical role in the accelerating the appearance of early markers of CCl4-induced fibrosis by moderate EtOH but did not contribute to EtOH-induced hepatocyte injury, steatosis, or expression of mRNA for some inflammatory cytokines.