Atherosclerosis Is Attenuated by Limiting Superoxide Generation in Both Macrophages and Vessel Wall Cells

Abstract

Objective-We previously showed that NAD(P)H oxidase deficiency significantly reduces atherosclerosis in apoE Ϫ/Ϫ mice. The present study was designed to determine the relative contribution of monocyte/macrophage versus vascular wall cell NAD(P)H oxidase to atherogenesis in this model. Methods and Results-Cell-specific NAD(P)H oxidase inhibition was achieved via allogenic, sex-mismatched bone marrow transplantation. Aortic atherosclerosis and superoxide production in apoE Ϫ/Ϫ mice (Control) with functional NAD(P)H oxidase in both monocytes/macrophages and vascular wall cells was compared with that in apoE Ϫ/Ϫ mice with nonfunctional monocyte/macrophage NAD(P)H oxidase (BMO) or nonfunctional vessel wall NAD(P)H oxidase (VWO). A significant decrease in superoxide production and atherosclerotic lesions was observed in BMO and VWO mice compared with control mice. Interestingly, BMO mice had significantly lower plasma oxidized LDL levels compared with control and VWO mice, whereas aortic sections of VWO mice showed decreased expression of cellular adhesion molecules compared with control and BMO mice. NAD(P)H oxidase deficiency also attenuated neointimal hyperplasia and mitogenic protein activation in apoE Ϫ/Ϫ mice after arterial injury. Conclusions-We conclude that (1) both monocyte/macrophages and vessel wall cells play critical roles in atherogenesis;(2) decrease in atherosclerosis results from attenuated superoxide generation in monocyte/macrophages or vessel wall cells; and (3) Key Words: Adhesion molecules Ⅲ signal transduction Ⅲ oxidized lipids Ⅲ reactive oxygen species Ⅲ thrombin R eactive oxygen species (ROS) derived from NAD(P)H oxidase have been strongly associated with experimental hypertension, 1 cardiac hypertrophy, 2 thrombosis, 3 restenosis, and atherosclerosis. 4 In humans, higher expression of NAD(P)H oxidase subunit proteins is associated with increased superoxide (O 2 ⅐Ϫ ) production and severity of atherosclerosis. 5 NAD(P)H oxidase is also an important source of increased O 2 ⅐Ϫ production in human diabetes mellitus, a risk factor for atherosclerosis. 6 All vascular wall cells-endothelial cells, smooth muscle cells (SMCs), and fibroblasts-as well as monocytes/macrophages contain NAD(P)H oxidases which are activated under pathophysiological conditions. The resultant ROS induce redox-sensitive signaling pathways that contribute to atherogenesis. 7 The phagocytic NAD(P)H oxidase contains the membranebound subunits gp91phox (Nox2) and p22phox, the catalytic site of the oxidase and the cytosolic components p47phox, p67phox, and G-protein Rac1 or Rac2. 8 Vascular NAD(P)H oxidases are similar in structure to phagocytic NAD(P)H oxidase, but have a distinct molecular composition. Endothelial cells and adventitial fibroblasts possess all the components of the phagocytic oxidase, whereas SMCs predominantly express homologues of gp91phox, Nox1 and Nox4. Mouse SMCs also express a p67phox homologue, Noxa1. 9 The activation of vascular NAD(P)H oxidases is constitutive as well as inducible in a manner similar ...

Molecular Biology of Atherosclerosis

“…Total aortic plaque surface area decreased as shown, but no decrease was seen in aortic sinus plaque (113). Bone marrow-derived and vascular wall cells appear to make equal contributions (1872). Also required for NF-B signaling by TNF␣ (and others) (1026).…”

“…In bone marrow transplant studies in ApoE-deficient mice, deficiency of p47 phox in the artery wall with normal bone marrow resulted in a 66% reduction in atherosclerosis and marked reduction of VCAM-1, ICAM-1, and P-selectin adhesion molecules expressed on both endothelial cells and VSMC as well as relative insensitivity to thrombin signaling. Transplant of p47 phox -defective, ApoE-deficient marrow into ApoE-deficient mice with wild-type p47 phox resulted in 53% attenuation of atherosclerosis, suggesting both vascular wall and macrophage production of superoxide contributes importantly to atherosclerosis progression (1872).…”

The Role of Vascular Endothelial Growth Factor-Induced Activation of NADPH Oxidase in Choroidal Endothelial Cells and Choroidal Neovascularization

“…32 Fresh-frozen sections of RPE-choroid were prepared from eye cups as described above. Control and experimental sections were placed on the same slide and processed under the same conditions.…”

Direct evidence of a role for Nox2 in superoxide production, reduced nitric oxide bioavailability, and early atherosclerotic plaque formation in ApoE−/−mice

“…These mice are hypercholesterolemic and spontaneously develop atherosclerotic plaques in the aorta and arterial branches thereof. Three previous studies have directly investigated the role of NADPH oxidases in atherogenesis in ApoE Ϫ/Ϫ mice through the genetic deletion of p47 phox (i.e., via generation of p47 phoxϪ/Ϫ /ApoE Ϫ/Ϫ double knockouts) (3,14,28). These studies indicated that, although p47 phox expression may not contribute to lesion development in the aortic sinus of ApoE Ϫ/Ϫ mice, it plays a major role in atherogenesis in the descending aorta, with the deletion of p47 phox resulting in up to an 80% smaller lesion area.…”