¹Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA

Correspondence: Dr J Chao, PhD, Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425-2211, USA. E-mail: chaoj@musc.edu

Received 7 March 2008; Revised 30 April 2008; Accepted 7 June 2008; Published online 1 September 2008.

Abstract

Oxidative stress causes cardiomyocyte death and subsequent ventricular dysfunction and cardiac remodeling after myocardial infarction (MI), thus contributing to high mortality in chronic heart failure patients. We investigated the effects of kallistatin in cardiac remodeling in a chronic MI rat model and in primary cardiac cells. Human kallistatin gene was injected intramyocardially 20 min after ligation of the left coronary artery. At 4 weeks after MI, expression of human kallistatin in rat hearts was identified by reverse transcription–polymerase chain reaction, immunohistochemistry and ELISA. Kallistatin administration improved cardiac performance, increased mean arterial pressure, decreased myocardial infarct size and restored left ventricular wall thickness. Kallistatin treatment significantly attenuated cardiomyocyte size and atrial natriuretic peptide expression. Kallistatin also reduced collagen accumulation, collagen fraction volume and expression of collagen types I and III, transforming growth factor-1 (TGF-1) and plasminogen activator inhibitor-1 in the myocardium. Inhibition of cardiac hypertrophy and fibrosis by kallistatin was associated with increased cardiac nitric oxide (NO) levels and decreased superoxide formation, NADH oxidase activity and p22-phox expression. Moreover, in both primary cultured rat cardiomyocytes and myofibroblasts, recombinant kallistatin inhibited intracellular superoxide formation induced by H₂O₂, and the antioxidant effect of kallistatin was abolished by N-nitro-L-arginine methyl ester (L-NAME), indicating a NO-mediated event. Kallistatin promoted survival of cardiomyocytes subjected to H₂O₂ treatment, and inhibited H₂O₂-induced Akt and ERK phosphorylation, as well as NF-B activation. Furthermore, kallistatin abrogated TGF--induced collagen synthesis and secretion in cultured myofibroblasts. This is the first study to demonstrate that kallistatin improves cardiac performance and prevents post-MI-induced cardiac hypertrophy and fibrosis through its antioxidant action.