Abstract 18683: Nox2-Containing NADPH Oxidase Deficiency Reduces Atherosclerosis and Improves Endothelial Healing in LDLr Knock Out Mice.
Background: Hypercholesterolemia is a major risk factor for the development of atherosclerotic cardiovascular diseases. Here we investigated the role of Nox2-derived reactive oxygen species (ROS) in the modulation of atherosclerosis and endothelial healing by hypercholesterolemia.
Methods and results: We generated a novel mouse model where Nox2 is knocked out in hypercholesterolemic LDLr knock out mice. Double knock out (LDLr−/−/Nox2−/−) and LDLr−/− mice were fed a high cholesterol diet for a total of 15 weeks. We found that LDLr−/−/Nox2−/− mice developed fewer aortic atherosclerotic lesions compared to LDLr−/− mice, as demonstrated by Oil Red O staining (14.2±1.0 vs. 19.6±0.4, p<0.001). Interestingly, we also demonstrate that after surgically-induced hindlimb ischemia, Nox2 deficiency is associated with a faster rate of blood flow recovery as assessed by Doppler Flow Ratios (DFR) at day 21 after surgery (0.66±0.04 vs. 0.49±0.04, p<0.05). In vitro, mouse aortic endothelial cells isolated from the aorta of Nox2−/− mice and exposed to oxLDL exhibit reduced superoxide generation (DHE) and lower rate of apoptosis (HOPI) compared to wild type (WT) endothelial cells. Nox2 deficiency also protects against the negative effects of oxLDL on endothelial cell functional activities. Therefore, oxLDL-dependent impairment of endothelial healing (scratch assay) and endothelial cell angiogenic activities (migration, tube formation) are completely rescued in Nox2−/− endothelial cells. Activation of the endothelium with subsequent adhesion of monocytes represents an essential step for the development of atherosclerosis. Here we show that Nox2 deficiency is associated with reduced endothelial cell activation following oxLDL exposure, as demonstrated by downregulation of e-selectin expression and reduced adhesion of THP-1 monocytes in Nox2−/− vs WT endothelial cells.
Conclusions: Nox2-containing NADPH oxidase deficiency protects against atherosclerosis and improves endothelial healing in hypercholesterolemic conditions. The potential mechanisms involved include reduced ROS generation, inhibition of oxLDL-dependent endothelial toxicity, and rescue of endothelial cell angiogenic properties.
- © 2010 by American Heart Association, Inc.