Angiotensin II Differentially Induces Matrix Metalloproteinase-9 and Tissue Inhibitor of Metalloproteinase-1 Production and Disturbs MMP/TIMP Balance

Angiotensin II, the main component of the renin-angiotensin system, is associated with cardiovascular diseases such as hypertension, vascular remodeling and inflammation. Remodeling process results from dysregulation of Matrix Metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). MMPs are considered as important target genes for angiotensin II. The aim of this study was to determine the effects of angiotensin II on MMP-9 and TIMP-1 production and MMP/TIMP balance in a monocytic cell type. Human monocytic U-937 cells were cultured and treated with 100 nM angiotensin II. Supernatants were analyzed for MMP-9 and TIMP-1 using ELISA and zymography methods. Real-time PCR was utilized to evaluate relative MMP-9 and TIMP-1 genes expression following treatments. Cytotoxicity potentials of treatments were determined by assaying lactate dehydrogenase leakage from the cells. Stimulation of the monocytic cells with angiotensin II significantly increased MMP-9 and TIMP-1 secretion as measured by ELISA (p < 0.05). It also augmented gelatinolytic activity of MMP-9 in the conditioned media as much as 49% (p < 0.05). Incubation of the cells with angiotensin II for 12 hr increased MMP-9 and TIMP-1 gene expression 2.7 and 1.8 folds, respectively (p < 0.05). Angiotensin II treatments did not establish significant cytotoxic effects. In summary, our data provide further evidences that monocytic MMP-9 is a major effector of angiotensin II. It is induced more efficiently than TIMP-1 by angiotensin II that leads to MMP/TIMP imbalance. Our data also reveal the pivotal participation of these cells in pathological cardiovascular remodeling mediated by angiotensin II.