Matrix metalloproteinase expression and activation in vascular smooth muscle cells and the coarctation-induced abdominal aortic aneurysm – the roles of elastin-derived peptides

Abstract

Previous studies from our laboratory showed that prolonged coarctation of a terminal segment of the abdominal aorta for 12 weeks induced the formation of abdominal aortic aneurysm (AAA) in mini pigs The coarctation-induced AAA exhibited elastic lamella fragmentation and degradation collagen remodeling and smooth muscle disarray consistent with degenerative AAA observed in human Gelatin zymography showed that activation of both matrix metalloproteinase (MMP)-9 and MMP-2 increased during AAA formation Real-time polymerase chain reaction (PCR) analysis further showed that mRNA levels of MMP-3 (4w) MMP-9 (4w) MMP-13 (4w and 12w) and MMP-19 (4w) were elevated in the AAA segment This study was aimed to investigate the potential roles of upregulated MMPs in the coarctation-induced AAA formation and whether elastin-derived peptides (EDPs) induce MMP expression secretion and activation in vascular smooth muscle cells (VSMCs) Immunohistochemical staining showed that MMP-3 levels increased in the medial VSMCs at 4w and 12w post-coarctation MMP-13 levels did not change markedly whereas MMP-19 increased in the media and intima at 4w post-coarctation In tissue homogenates of the distal AA MMP-3 activity detected with casein zymography did not change significantly The effect of MMP-3 overexpression on VSMC migration activity and actin cytoskeleton organization was further examined in cultured human aortic VSMCs overexpressing MMP-3 encoded by lentivirus VSMCs overexpressing mCherry-MMP-3 exhibited apparently higher invasion activity stimulated with platelet-derived growth factor (PDGF)-BB than cells expressing mCherry vector alone On fibronectin-coated polyacrylamide gels with stiffness close to the aortic wall (~20 kPa) preliminary results showed that MMP-3-expressing VSMCs exhibited better adhesion and spreading with more prominent actin filaments compared to vector-expressing VSMCs In human aortic VSMCs treatment of EDPs for 24 hours increased the secretion of pro-MMP-2 pro-MMP-3 and pro-MMP-9 in a dose-dependent manner Zymography analysis showed that activation of secreted pro-MMP-9 but not pro-MMP-2 or pro-MMP-3 was stimulated by EDPs treatment In contrast the expression and secretion levels of pro-MMP-13 and pro-MMP-19 in VSMCs were low and EDPs treatment had no effect In addition EDPs treatment did not affect VSMCs proliferation rate and migration activities assessed with cell counting and wound-healing assay These results suggested that increased MMP-3 expression and/or secretion during coarctation-induced AAA formation may promote actin filament reorganization and migration activity of VSMCs and hence vascular remodeling In addition EDPs derived from elastic lamella fragmentation may contribute to vascular remodeling through stimulating the secretion and/or activation of pro-MMP-2 pro-MMP-3 and pro-MMP-9

Date of Award	2016 Aug 1
Original language	English
Supervisor	Meei-Jyh Jiang (Supervisor)