TGF-β1 attenuates myocardial ischemia-reperfusion injury via inhibition of upregulation of MMP-1

Abstract

Ischemia-reperfusion (I/R) is thought to upregulate the expression and activity of matrix metalloproteinases (MMPs), which regulate myocardial and vascular remodeling. Previous studies have shown that transforming growth factor-β1 (TGF-β1) can attenuate myocardial injury induced by I/R. TGF-β1 is also reported to suppress the release of MMPs. To study the modulation of MMP-1 by TGF-β1 in I/R myocardium, Sprague-Dawley rats were given saline and subjected to 1 h of myocardial ischemia [total left coronary artery (LCA) ligation] followed by 1 h of reperfusion ( n = 9). Parallel groups of rats were pretreated with recombinant TGF-β1(rTGF-β1, 1 mg/rat, n = 9) before reperfusion or exposure to sham I/R (control group). I/R caused myocardial necrosis and dysfunction, indicated by decreased first derivative of left ventricular pressure, mean arterial blood pressure, and heart rate (all P < 0.01 vs. sham-operated control group). Simultaneously, I/R upregulated MMP-1 ( P < 0.01). Treatment of rats with rTGF-β1 reduced the extent of myocardial necrosis and dysfunction despite I/R (all P < 0.01). rTGF-β1 treatment also inhibited the upregulation of MMP-1 in the I/R myocardium ( P < 0.05). To determine the direct effect of MMP-1 on the myocardium, isolated adult rat myocytes were treated with active MMP-1, which caused injury and death of cultured myocytes, measured as lactate dehydrogenase release and trypan blue staining, in a dose- and time-dependent manner ( P < 0.05). Pretreatment with PD-166793, a specific MMP inhibitor, attenuated myocardial injury and death induced by active MMP-1. The present study for the first time shows that MMP-1 can directly cause myocyte injury or death and that attenuation of myocardial I/R injury by TGF-β1 may, at least partly, be mediated by the inhibition of upregulation of MMP-1.