Simvastatin inhibits lipopolysaccharide-induced tumor necrosis factor-α expression in neonatal rat cardiomyocytes: The role of reactive oxygen species

Tumor necrosis factor-α (TNF-α) is implicated in heart failure and cardiomyocytes themselves can express TNF-α. Nevertheless, the mechanisms and regulations of TNF-α expression in cardiomyocytes remain poorly understood. The present study was to investigate the effects of simvastatin on TNF-α expression in cardiomyocytes and the underlying molecular mechanisms. In neonatal rat cardiomyocytes, RT-PCR and ELISA showed lipopolysaccharide (LPS)-induced TNF-α expression was attenuated by simvastatin pretreatment in a dose-dependent manner. The reactive oxygen species (ROS) scavenger N-acetylcysteine and the NADPH oxidase inhibitor diphenyleneiodonium also inhibited the LPS-induced expression of TNF-α. Dichlorofluorescein-fluorescence and cytochrome c reduction assay indicated LPS increased ROS generation and NADPH oxidase activity in cardiomyocytes, which were abrogated by simvastatin. Furthermore, similar to LPS, exogenous hydrogen peroxide also increased TNF-α secretion, but simvastatin did not significantly affect the hydrogen peroxide-induced TNF-α secretion. All the effects of simvastatin as mentioned above were completely reversed by concomitant pretreatment with mevalonate, a key intermediate during cholesterol synthesis. These results suggest that simvastatin attenuates LPS-induced TNF-α expression in cardiomyocytes via inhibition of activation of NADPH oxidase and subsequent ROS generation.