Regulation of Matrix Metalloproteinases 2 and 9 Activities by Peroxynitrites in Term Placentas From Type 2 Diabetic Patients

Matrix metalloproteinases (MMPs) are proteolytic enzymes related to a proinflammatory environment in several diseases, including diabetes, which can be activated by reactive nitrogen species. This work aimed to determine MMP-2 and MMP-9 activities and nitration in term placentas from type 2 diabetic patients and verify the hypothesis that peroxynitrites are positive regulators of placental MMP-2 and MMP-9 activities. For this purpose, term placentas from healthy and type 2 diabetic patients were analyzed for MMP-2 and MMP-9 levels and activities, protein nitration, and nitration of MMP-2 and MMP-9. Villous explants were cultured in the presence of peroxynitrites for further evaluation of MMP-2 and MMP-9 activities. We found that MMP-2 and MMP-9 activities were increased in term placentas from diabetic patients. These changes were found even when MMP-2 protein concentrations were diminished and MMP-9 protein concentrations were not changed in the diabetic group. Increased protein nitration and specific nitration of MMP-2 and MMP-9 were found in term placentas from diabetic patients. Peroxynitrites were able to increase the activity of placental MMP-2 and MMP-9. Taken together, this study has shown for first time that peroxynitrites can nitrate and activate MMP-2 and MMP-9 in the placenta, a nitrative pathway possibly related to MMPs overactivity in the placentas from type 2 diabetic patients.