Abstract 18898: RECK Inhibits EGF Receptor Activation and MMP Induction, and Blunts Neointimal Hyperplasia in the Rat
Introduction: The proliferation and migration of arterial SMCs are key events in the vascular restenosis that follows angioplasty, atherosclerosis, and vein grafting. Furthermore, SMC migration and neointimal hyperplasia are promoted by degradation of the ECM by MMPs. Reversion-inducing-cysteine-rich protein with Kazal motifs (RECK) is a unique, membrane-anchored MMP inhibitor. It also inhibits the pro-mitogenic EGF receptor signaling. Since MMP induction and EGFR activation plays a role in the pathogenesis of NH, we hypothesized that overexpressing RECK would inhibit NH in a rat carotid artery angioplasty model.
Methods: Rats (male, 5 mo) underwent left carotid artery injury by balloon catheterization (n=12/group). In a subset of animals, the injured portion of the artery was injected with adenovirus expressing full-length rat RECK cDNA (Ad.RECK; 100 μl, 1x1010 pfu/ml, 30 min). Ad.GFP served as a control. After 14 days and following BrdU administration, rats were euthanized, and both carotid arteries collected for histology and morphometric analysis. RECK, MMP, EGFR and IL-18 expressions were analyzed by immunoblotting and activity assays. IL-18 signaling pathways regulated by RECK were investigated in primary rat carotid artery SMC.
Results: In the control group, endogenous levels of RECK in the injured arteries were markedly suppressed after one day, and remained suppressed throughout the 14 days. In contrast, IL-18 expression, and MMP2 and EGFR activation were markedly increased following injury, and remained elevated. Intimal/medial (I/M) ratio increased gradually; 0.6±0.1 at 7 days and 1.1±0.2 after 14 days. Ad.RECK (vs. Ad.GFP) inhibited MMP2 and EGFR activation, and decreased the I/M ratio by 67% (P < 001 vs. Ad.GFP). In vitro, while IL-18 stimulated SMC migration and proliferation, RECK overexpression blunted MMP2 activation and EGFR phosphorylation, enhanced p27Kip1 expression, and inhibited migration (71%) and proliferation (62%).
Conclusions: Neointimal hyperplasia suppresses RECK expression, and forced expression of RECK negatively regulates SMC proliferation and migration both in vivo and in vitro. Strategies that upregulate RECK may have therapeutic potential in hyperplastic vascular diseases.
Author Disclosures: N.A. Das: None. A.J. Carpenter: None. S. Jalahalli Mariswamy: None. S.N. Murthy: None. E.A. Pankey: None. T. Yoshida: None. P. Kadowitz: None. A.J. Valente: None. C. Bysani: None.
- © 2014 by American Heart Association, Inc.