Transgenic Overexpression of Aldehyde Dehydrogenase-2 Rescues Chronic Alcohol Intake–Induced Myocardial Hypertrophy and Contractile Dysfunction

Abstract

Background— Chronic alcoholism leads to the onset and progression of alcoholic cardiomyopathy through toxic mechanisms of ethanol and its metabolite, acetaldehyde. This study examined the impact of altered acetaldehyde metabolism through systemic transgenic overexpression of aldehyde dehydrogenase-2 (ALDH2) on chronic alcohol ingestion–induced myocardial damage. Methods and Results— ALDH2 transgenic mice were produced with the chicken β-actin promoter. Wild-type FVB and ALDH2 mice were placed on a 4% alcohol diet or a control diet for 14 weeks. Myocardial and cardiomyocyte contraction, intracellular Ca²⁺ handling, histology (hematoxylin and eosin, Masson trichrome), protein damage, and apoptosis were determined. Western blot was used to monitor the expression of NADPH oxidase, calcineurin, apoptosis-stimulated kinase (ASK-1), glycogen synthase kinase-3β (GSK-3β), GATA4, and cAMP-response element binding (CREB) protein. ALDH2 reduced the chronic alcohol ingestion–induced elevation in plasma and tissue acetaldehyde levels. Chronic alcohol consumption led to cardiac hypertrophy, reduced fractional shortening, cell shortening, and impaired intracellular Ca²⁺ homeostasis, the effect of which was alleviated by ALDH2. In addition, the ALDH2 transgene significantly attenuated chronic alcohol intake–induced myocardial fibrosis, protein carbonyl formation, apoptosis, enhanced NADPH oxidase p47^phox and calcineurin expression, as well as phosphorylation of ASK-1, GSK-3β, GATA4, and CREB. Conclusions— The present results suggest that transgenic overexpression of ALDH2 effectively antagonizes chronic alcohol intake–elicited myocardial hypertrophy and contractile defect through a mechanism that is associated, at least in part, with phosphorylation of ASK-1, GSK-3β, GATA4, and CREB. These data strongly support the notion that acetaldehyde may be an essential contributor to the chronic development of alcoholic cardiomyopathy.