Abstract 20940: The Pericellular Proteolysis Balance is Altered in the Vessel Wall of Factor VII Activating Protease (FSAP)−/− Mice During Neointima Formation
The Marburg I single nucleotide polymorphism (MI-SNP) in the Factor VII Activating Protease (FSAP) gene is a severe risk factor for carotid stenosis in humans. In contrast to wild type (WT)-FSAP, MI-FSAP is a poor activator of pro-urokinase (pro-uPA) and fails to specifically cleave platelet-derived growth factor-BB and to inhibit neointima formation in vivo. The objective of this work was to study the pericellular proteolysis system in the vasculature of FSAP−/− mice during arterial remodeling. In a wire induced injury model of neointima formation, we determined neointimal lesion size and expression levels of uPA and matrix metalloproteases (MMP)−2/−9 in FSAP−/− mice compared to WT controls. The neointimal lesion size in FSAP−/− mice was enhanced at 2 weeks after dilation (NI/media ratio 2.46±0.34 vs. 1.69±0.09, P<0.05, n=7). Quantitative zymography of excised arteries at 2 weeks after dilation showed that the levels of active uPA and latent pro-MMPs did not differ between the two groups. Interestingly, we detected significantly increased expression levels of active MMP−2 (2-fold, n=6) and particularly active MMP-9 (5-fold, n=6) in the arteries of FSAP−/− mice. Immunohistochemical staining for the pan-leukocyte marker CD45 revealed an enhanced accumulation of absolute leukocyte numbers as well as an increased ratio of leukocytes/ all cells within the vascular wall of FSAP−/− mice compared to WT controls at 2 weeks after injury (P<0.05, n=7). In vitro, we did not observe any changes in mRNA or protein expression levels of uPA or MMP−2/−9 in vascular smooth muscle cells or endothelial cells after treatment of the cells with FSAP. In conclusion, exogenous application of FSAP attenuates NI formation whereas FSAP knockdown increases lesion formation after wire-induced injury. The altered balance of the pericellular proteolysis system in FSAP−/− mice is very likely derived from infiltrating inflammatory cells and could be the mechanism to explain the association of MI-SNP carriers (akin to a naturally occurring knock down) with carotid stenosis.
- © 2010 by American Heart Association, Inc.