Upregulation of Nox-Based NAD(P)H Oxidases in Restenosis After Carotid Injury

Abstract

Abstract-Restenosis, a frequent complication of coronary angioplasty, is associated with increased superoxide (O 2 · Ϫ ) production. Although the molecular identity of the responsible oxidase is unclear, an NAD(P)H oxidase appears to be involved. In smooth muscle, p22phox and 2 homologues of gp91phox, nox1 and nox4, are expressed, whereas fibroblasts contain gp91phox. To begin investigating the possibility that these oxidase components might contribute to the increased O 2 · Ϫ that accompanies neointimal formation, we measured their expression after balloon injury of the rat carotid artery. The increase in O 2 · Ϫ production 3 to 15 days after surgery was not due to inflammatory cell infiltration but appeared to be derived from medial and neointimal smooth muscle cells and adventitial fibroblasts. Nox1 and p22phox mRNAs were increased 2.7-and 3.6-fold, respectively, at day 3 after injury and remained elevated for 15 days. gp91Phox was increased 7 to 15 days after injury, and nox4 expression was increased 2-fold, but only at day 15 after surgery. These results confirm and extend our previous in vitro data and suggest that in the vasculature, the nox-based NAD(P)H oxidases serve different functions. This dynamic regulation of oxidase components may be critical to smooth muscle phenotypic modulation in restenosis and atherosclerosis. Key Words: neointimal formation Ⅲ superoxide Ⅲ NAD(P)H oxidase Ⅲ balloon injury Ⅲ nox R estenosis is a frequent complication of percutaneous transluminal coronary angioplasty. This pathophysiological process is characterized by arterial wall remodeling and intimal hyperplasia, resulting in luminal narrowing at the site of balloon dilation. Immediately after endothelial denudation, extensive death of medial smooth muscle cells (SMCs) occurs, which is then followed by significant proliferation of the remaining SMCs. 1 These cells, together with activated adventitial cells (myofibroblasts), migrate through the internal elastic lamina to form the neointimal layer. The mechanisms responsible for the cellular events resulting in restenosis are incompletely understood.

Nox enzymes, ROS, and chronic disease: An example of antagonistic pleiotropy

“…Oscillatory sheer stress is associated with induction of bone morphogenic protein 4 (BMP4) [82], which induces Nox1 and p47phox, resulting in an oxidative stress that leads to ICAM-1 expression and monocyte adhesion [81]. Nox1 expression increases ~3-fold following balloon injury and precedes restenosis and atherosclerosis [83]. This in turn led to monocyte infiltration and a vicious cycle of increasing oxidant stress.…”

17β-Estradiol reverses shear-stress-mediated low density lipoprotein modifications

“…ECs produce ROS and RNS from the enzymes and ·NO synthase and by specific homologues of NADPH oxidase (gp91 phox , Nox1, and Nox4) [41]. We previously demonstrated that NADPH oxidases were capable of producing high levels of ROS in blood vessels in response to specific stimuli arising from flow conditions.…”

Regulation of smooth muscle by inducible nitric oxide synthase and NADPH oxidase in vascular proliferative diseases

“…Using the balloon injury model in the rat, Griendling and colleagues observed that Nox1 as well as p22phox mRNA was upregulated 3 days post injury and sustained through 15 days post injury while there was an increase in gp91phox at 7 days post injury which also sustained through 15 days [149]. In addition Nox4 mRNA remained unchanged until 15 days post injury where an increase in the mRNA was observed.…”

“…The same authors used immunohistochemistry to confirm that p22phox expression was detected basally in the adventitia of the vessel, but appeared in the medial smooth muscle layer by 7 days post injury and then most abundantly in the neointima by 10 days post injury, where Nox4 was only detected in medial and neointimal cells. However, they were not able to establish the site of Nox1 expression [149]. Moe et al investigated Nox expression in human aortic smooth muscle cells in response to the pro-inflammatory cytokine TNF-α.…”