Abstract 715: Cytochrome P450 1B1 Gene Disruption Prevents Neointimal Growth in Wire-Injured Carotid Artery of Male Mice

Abstract

We have previously reported that cytochrome P450 1B1 (CYP1B1), a heme-thiolate monooxygenase expressed in cardiovascular tissues, contributes to the development of hypertension and its associated pathogenesis in various experimental animal models. The current study was conducted to determine the contribution of CYP1B1 in neointimal growth following wire injury of carotid artery in 8 week-old male Cyp1b1+/+ and Cyp1b1-/- mice. The left carotid artery was injured with a metal wire and denudation of the endothelial layer was confirmed by the absence of von Willebrand factor staining cells, 1 day after the injury in both Cyp1b1+/+ and Cyp1b1-/- mice. After 14 days of injury, the mice were sacrificed, and both injured and uninjured contralateral carotid arteries were collected for histological and immunohistochemical analysis. The wire injury caused neointimal growth as indicated by increased intimal area, intima/media ratio and elastin disorganization in carotid arteries of Cyp1b1+/+ mice; these changes were minimized in the carotid arteries of Cyp1b1-/- mice. Vascular smooth muscle cells (VSMCs) were found to be the major cellular component of these neointima, as evident by positive staining for α-smooth muscle actin. We also found increased infiltration of inflammatory and immune cells as indicated by expression of CD68+ macrophages and CD3+ T-cells, respectively, in the wire-injured carotid arteries of Cyp1b1+/+ mice but not Cyp1b1-/- mice. Administration of 4-Hydroxy-2, 2, 6, 6-tetramethylpiperidine 1-oxyl (TEMPOL), a superoxide dismutase mimetic, in drinking water (2 mmoles/l), attenuated the neointimal growth in wire-injured carotid arteries of Cyp1b1+/+ mice. Furthermore, in vitro studies showed significant reduction of angiotensin II-induced migration, proliferation and protein synthesis in VSMCs from Cyp1b1-/- compared to Cyp1b1+/+ mice. These data suggest that Cyp1b1-dependent oxidative stress contributes to the neointimal growth caused by wire injury of carotid arteries of male mice. Therefore, inhibitors of Cyp1b1 could be useful in the treatment of restenosis caused by vascular injury including balloon angioplasty, atherosclerosis and diabetes in males.