Transforming Growth Factor-β Blockade Down-Regulates the Renin-Angiotensin System and Modifies Cardiac Remodeling after Myocardial Infarction

After myocardial infarction (MI), the heart may undergo progressive ventricular remodeling, resulting in a deterioration of cardiac function. TGF-β is a key cytokine that both initiates and terminates tissue repair, and its sustained production underlies the development of tissue fibrosis, particularly after MI. We investigated the effects of a novel orally active specific inhibitor of the TGF-β receptor 1 (SD-208) in an experimental model of MI. Mice underwent ligation of the left coronary artery to induce MI and were subsequently treated for 30 d after infarction with either SD-208 or a vehicle control. Blockade of TGF-β signaling reduced mean arterial pressure in all groups. SD-208 treatment after MI resulted in a trend for reduced ventricular and renal gene expression of TGF-β-activated kinase-1 (a downstream modulator of TGF-β signaling) and a significant decrease in collagen 1, in association with a marked decrease in cardiac mass. Post-MI SD-208 treatment significantly reduced circulating levels of plasma renin activity as well as down-regulating the components of the cardiac and renal renin-angiotensin system (angiotensinogen, angiotensin converting enzyme, and angiotensin II type I receptor). Our findings indicate that blockade of the TGF-β signaling pathway results in significant amelioration of deleterious cardiac remodeling after infarction.