Abstract 589: ADAM10: A Novel Metalloprotease Expressed In Human Atherosclerosis And Involved In Angiogenesis
Neovascularization has been shown to be associated with atherosclerotic plaque growth and instability, thereby increasing the risk of clinical complications. Although metalloproteases have been implicated in atherosclerosis and angiogenesis, mainly by their matrix-degrading capacity, little is known about their function in endothelial cells (EC). In a Yeast-two hybrid assay using the intracellular part of VEGFR and a human placenta cDNA library, we identified A Disintegrin And Metalloprotease ADAM10 as a binding partner of VEGFR2. ADAM10 is known to be involved in chemotaxis, cell adhesion and migration, but a role in EC function, angiogenesis and atherosclerosis is not known. Therefore we examined expression of ADAM10 in atherosclerosis and its role in angiogenesis. Using immunohistochemistry we showed high ADAM10 expression in various cell types of human atherosclerotic plaques including EC and macrophages. Strikingly, ADAM10 expression was found in plaque microvessels, indicating an association with plaque angiogenesis. To investigate a causal role for ADAM10 in atherosclerosis and angiogenesis, we examined the migratory capacity of monocytes and EC after ADAM10 inhibition. Human blood monocytes were isolated from healthy volunteers (n=4) using immunomagnetic isolation. Migration of monocytes treated with the selective ADAM10 inhibitor GI254023X or DMSO (control) was assessed using the modified Boyden chamber. Selective ADAM10 inhibition reduced both basal migration (chemokinesis) and directed migration of monocytes towards chemotactic factors (30–50% reduction, p=0.024). Similarly, migration of PAEC-KDR (Porcine Aortic EC stably expressing human VEGFR2, n=3) towards VEGF-A as well as their chemokinesis was 40% reduced by ADAM10 inhibition (p=0.037). In conclusion, ADAM10, a metalloprotease previously unknown in atherosclerosis or angiogenesis, is highly expressed in human atherosclerotic plaques. ADAM10 expression was associated with plaque neovascularization and its activity is required for migration/chemotaxis of monocytes and EC. These data indicate a role for ADAM10 in (plaque) angiogenesis and atherosclerosis. This might open perspectives for novel therapeutic interventions for atherosclerotic diseases.