Inhibition of Rho-kinase ameliorates myocardial remodeling and fibrosis in pressure overload and myocardial infarction: role of TGF-β1-TAK1.

Inhibition of Rho-kinase displays vasodilation property although its effect on cardiac remodeling in heart against pressure overload and ischemia has not been fully elucidated. The present study was designed to examine the effect of fasudil, a Rho-kinase (ROCK) inhibitor, on myocardial remodeling and underlying mechanisms in pressure overload and myocardial infarction (MI) mice. Pressure overload was produced by constriction of the transverse aorta (TAC) for 3 weeks. Left ventricular (LV) geometry, cardiac hypertrophy, fibrosis, and remodeling were evaluated by transthoracic echocardiography and cardiac histology. Expressions of the hypertrophic and profibrotic markers were analyzed in TAC and MI mice with or without fasudil treatment. LV cavity dilatation and dysfunction evaluated by echocardiography were significantly suppressed in the fasudil-treated MI group compared with the MI group (P<0.05); however, there were no significant difference between the TAC group and the fasudil-treated TAC group. Inhibition of ROCK exhibited reduced interstitial fibrosis, which was observed both in TAC and MI mice (P<0.05). The beneficial effects of fasudil were closely associated with the change of the specific profibrotic gene expression and TGF-β1-TAK1 pathway. Taken together, these results indicate that Rho-kinase is substantially involved in the myocardial remodeling after TAC and MI associated with upregulation of profibrotic gene expression and TGF-β1-TAK1 pathway; further suggest the protective effect of fasudil on heart against pathological stimuli by inhibiting reactive fibrosis.