Inhibition of myeloid differentiation factor-2 attenuates obesity-induced cardiomyopathy and fibrosis

Obesity causes cardiovascular diseases, including cardiac hypertrophy and remodeling, via chronic tissue inflammation. Myeloid differentiation factor-2 (MD2), a binding protein of lipopolysaccharide, is functionally essential for the activation of proinflammatory pathways in endotoxin-induced acute inflammatory diseases. Here we tested the hypothesis that MD2 plays a central role in obesity-induced cardiomyopathy. Wildtype or MD2 knockout mice were fed with a high fat diet (HFD) or normal diet (Control) for total 16 weeks, and MD2 inhibitor L6H21 (20 mg/kg) or vehicle (1% CMC-Na) were administered from the beginning of the 9th week. HFD induced significant weight gain and cardiac hypertrophy, with increased cardiac fibrosis and inflammation. L6H21 administration or MD2 knockout attenuated HFD-induced obesity, inflammation and cardiac remodeling. In vitro exposure of H9C2 cells to high lipids induced cell hypertrophy with activated JNK/ERK and NF-κB pathways, which was abolished by pretreatment of MD2 inhibitor L6H21. Our results demonstrate that MD2 is essential to obesity-related cardiac hypertrophy through activating JNK/ERK and NF-κB-dependent cardiac inflammatory pathways. Targeting MD2 would be a therapeutic approach to prevent obesity-induced cardiac injury and remodeling.