Abstract 3643: Nox2-Deficient Mice are Protected Against Hypercholesterolemia-Induced Inhibition of Neovascularization
Hypercholesterolemia is a major risk factor for cardiovascular diseases. It is also associated with impaired neovascularization in response to ischemia. Here we investigated the role of NADPH oxidase-dependent reactive oxygen species (ROS) generation for the modulation of neovascularization by hypercholesterolemia. Mice deficient for the Nox2-containing NADPH oxidase (Nox2−/−) and control (Nox2+/+) mice were fed a high cholesterol diet for a total of 15 weeks. After three months, hindlimb ischemia was surgically induced by femoral artery removal. We found that Nox2−/− mice displayed reduced oxidative stress in ischemic tissues (nitrotyrosine immunostaining) compared to controls. This was associated with a significantly improved angiogenic response, as demonstrated by an increased capillary density (CD31 immunostaining) in ischemic muscles. In vitro, endothelial cells isolated from the aorta of Nox2−/− mice or HUVECs treated with the NADPH oxidase inhibitor apocynin exhibit reduced superoxide formation (DHE staining). This was associated with protection against oxidized LDL-induced inhibition of endothelial cell migration (Boyden chamber) and angiogenic activities (matrigel assay). We also found that Nox2 deficiency is associated with preserved endothelial progenitor cells (EPCs) functional activities (adhesion, migration) in mice exposed to a high cholesterol diet. NADPH oxidase deficiency protects against hypercholesterolemia-induced impairment of neovascularization. The potential mechanisms involved include reduced ROS generation and preserved angiogenic activities of EPCs and mature endothelial cells.