Olmesartan ameliorates pressure overload-induced cardiac remodeling through inhibition of TAK1/p38 signaling in mice.

AIMS: Many studies have demonstrated the potent effects of ARB administration on heart failure. However, the mechanism of the potent effects of ARB on cardiac remodeling is less well understood. We investigated the role of Olmesartan on the fibrosis and hypertrophy in mouse heart.

MATERIALS AND METHODS: We employed TAC surgery, a mouse model of chronic cardiac failure. All the mice were separated into three groups: the sham group, TAC group and TAC plus Olmesartan group (given Olmesartan treatment after TAC). We analyzed left ventricle remodeling, and function by echocardiography or pathology. We further detected the level of marker genes involved in fibrosis and hypertrophy and in cultured neonatal rat cardiac fibroblasts and myocytes infected by constitutively active TAK1 and p38MAPK. After TAC, all the mice developed hypertrophy, worse cardiac function and malignant remodeling in left ventricle.

KEY FINDINGS: Olmesartan improved heart remodeling and function without changing pressure of blood. Moreover, Olmesartan reduced the level of transforming growth factor β activated kinase-1 (TAK1) and phospho-p38MAPK. In neonatal rat cardiac fibroblast cells and cardiomyocytes, Olmesartan also decreased TAK1 and p38MAPK activation triggered by TGFβ1 or AngII. The inhibitory effect of Olmesartan was abrogated by overexpression of constitutively active TAK1 and p38MAPK by adenovirus system.

SIGNIFICANCE: Our results suggest Olmesartan improves heart remodeling and function induced by pressure overload. P38MAPK inactivation attenuated by olmesartan via inhibition of TAK1 pathway plays an important role in the process.