Etanercept protects rat cardiomyocytes against hypertrophy by regulating inflammatory cytokines secretion and cell apoptosis

Abstract We aimed to investigate the effect of etanercept, a tumor necrosis factor-a (TNF-a) inhibitor, on rat cardiomyocyte hypertrophyand its underlying mechanism. Primary neonatal rat cardiomyocytes were isolated from Sprague-Dawley rats. The model of ratcardiomyocyte hypertrophy was induced by endothelin, and then treated with different concentrations of etanercept (1, 10, and50 mM). After treatment, cell counts, viability and cell apoptosis were evaluated. The mRNA levels of myocardial hypertrophymarker genes, including atrial natriuretic factor (ANF), matrix metalloproteinase (MMP)-9 and MMP-13, were detected by qRT-PCR, and the expressions of apoptosis-related proteins (Bcl-2 and Bax) were measured by western blotting. The protein levelsof transforming growth factor-b1 (TGF-b1), interleukin (IL)-1b, IL-6, leukemia inhibitory factor (LIF) and cardiotrophin-1 (CT-1)were determined using enzyme linked immunosorbent assay (ELISA) kits. In the present study, TNF-a level in cardiomyocyteswith hypertrophy was significantly enhanced (Po0.05). Compared to the model group, cell number and viability were sig-nificantly increased and ratio of apoptotic cells was reduced by etanercept (Po0.05, Po0.01, or Po0.001). In addition,etanercept remarkably reduced the mRNA levels of ANF, MMP-9 and MMP-13, inhibited the expression of Bax, and increasedthe expression of Bcl-2 compared to the model group (Po0.05). ELISA results further showed that etanercept lowered thelevels of IL-1b, IL-6, LIF and CT-1 but not TGF-b1 compared to the model group (Po0.05). Etanercept may protect ratcardiomyocytes from hypertrophy by inhibiting inflammatory cytokines secretion and cell apoptosis.Key words: Tumor necrosis factor-a inhibitor; Endothelin; Myocardial hypertrophy; Cell apoptosis; Inflammatory response