Macrophages modulate cardiac function in lipotoxic cardiomyopathy

Schilling JD, Machkovech HM, Kim AH, Schwedwener R, Schaffer JE. Macrophages modulate cardiac function in lipotoxic cardiomyopathy. Am J Physiol Heart Circ Physiol 303: H1366-H1373, 2012. First published October 5, 2012; doi: 10.1152/ajpheart.00111.2012.-Diabetes is associated with myocardial lipid accumulation and an increased risk of heart failure. Although cardiac myocyte lipid overload is thought to contribute to the pathogenesis of cardiomyopathy in the setting of diabetes, the mechanism(s) through which this occurs is not well understood. Increasingly, inflammation has been recognized as a key pathogenic feature of lipid excess and diabetes. In this study, we sought to investigate the role of inflammatory activation in the pathogenesis of lipotoxic cardiomyopathy using the alpha-myosin heavy chain promoter-driven long-chain acylCoA synthetase 1 (MHC-ACS) transgenic mouse model. We found that several inflammatory cytokines were upregulated in the myocardium of MHC-ACS mice before the onset of cardiac dysfunction, and this was accompanied by macrophage infiltration. Depletion of macrophages with liposomal clodrolip reduced the cardiac inflammatory response and improved cardiac function. Thus, in this model of lipotoxic cardiac injury, early induction of inflammation and macrophage recruitment contribute to adverse cardiac remodeling. These findings have implications for our understanding of heart failure in the setting of obesity and diabetes.