Abstract P601: Matrix Metalloproteinase 2 Plays An Important Role In Angiotensin Ii-induced Vascular Injury Mediated In Part Through Epidermal Growth Factor Receptor Activation In Vascular Smooth Muscle Cells

Abstract

Background: Matrix metalloproteinase 2 (MMP2) is involved in cardiovascular disease. Whether MMP2 plays a role in hypertension and vascular damage is unknown. We hypothesized that Mmp2 knockout will prevent angiotensin (Ang) II-induced blood pressure (BP) rise and vascular injury. Methods: Ten to 12-week-old male Mmp2 knockout (Mmp2-/-) and wild-type (WT) mice were infused with Ang II (1000 ng/kg/min, SC) for 14 days. Systolic BP was measured by telemetry, mesenteric arteries (MA) endothelial function and vascular remodeling by pressurized myography. In aortic wall or perivascular fat (PVAT), reactive oxygen species (ROS) generation was determined using dihydroethidium staining, and vascular cell adhesion protein 1 (VCAM-1), monocyte chemotactic protein-1 (MCP-1) expression and monocyte/macrophage infiltration by immunofluorescence. Spleen T cells and monocyte profile were assessed by flow cytometry. Vascular smooth muscle cells (VSMCs) were isolated from MA of WT and Mmp2 knockout mice, stimulated 5 min with 100 nM Ang II and epidermal growth factor receptor (EGFR) phosphorylation measured by Western-Blotting. Results: Ang II increased Systolic BP (172±7 vs 122±3, P<0.01), decreased MA vasodilatory responses to acetylcholine (33±5% vs 83±3%, P<0.01) and increases MA media-to-lumen ratio (5±0% vs 3±0%, P<0.01), media cross-sectional area (7224±467 vs 5345±336 μm2, P<0.05), and stiffness (P<0.01), as shown by a leftward shift of the stress/strain relationship, in WT. Furthermore, Ang II enhanced aortic ROS generation (73±11 vs 6±1 RFU/μm2, P<0.01), aortic VCAM-1 (17±3 vs 5±3 RFU/μm2, P<0.01) and MCP-1 expression (71±14 vs 11±3 RFU/μm2, P<0.01) and PVAT monocyte/macrophage infiltration (32±5 vs 4±0 RFU/μm2, P<0.05), and spleen activated CD4+CD69+ and CD8+CD69+ T cells and pro-inflammatory Ly-6Chi monocytes (17±2 vs 10±1%, 11±1 vs 5±1% and 53±6 vs 25±2%, respectively, P<0.05) in WT. Ang II increased EGFR phosphorylation in VSMCs in vitro (1.91±0.19 vs 1.0±0.0%, P<0.05). Mmp2 knockout prevented or reduced all of the above except BP elevation (P<0.05). Conclusion: MMP2 plays an important role in Ang II-induced vascular injury, which could be mediated at least in part through EFGR activation in VSMCs.