Selective inactivation of NADPH oxidase 2 causes regression of vascularization and the size and stability of atherosclerotic plaques

Abstract

Background: A variety of NADPH oxidase (Nox) isoforms including Noxs 1, 2, 4 and 5 catalyze the formation of reactive oxygen species (ROS) in the vascular wall. The Nox2 isoform complex has arguably received the greatest attention in the progression of atherogenesis in animal models. Thus, in the current study we postulated that specific Nox2 oxidase inhibition could reverse or attenuate atherosclerosis in mice fed a high-fat diet.

Methods: We evaluated the effect of isoform-selective Nox2 assembly inhibitor on the progression and vascularization of atheromatous plaques. Apolipoprotein E-deficient mice (ApoE-/-) were fed a high fat diet for two months and treated over 15 days with Nox2ds-tat or control sequence (scrambled); 10 mg/kg/day, i.p. Mice were sacrificed and superoxide production in arterial tissue was detected by cytochrome C reduction assay and dihydroethidium staining. Plaque development was evaluated and the angiogenic markers VEGF, HIF1-α and visfatin were quantified by real time qRT-PCR. MMP-9 protein release and gelatinolytic activity was determined as a marker for vascularization.

Results: Nox2ds-tat inhibited Nox-derived superoxide determined by cytochrome C in carotid arteries (2.3 ± 0.1 vs 1.7 ± 0.1 O2(•-) nmol/min*mg protein; P < 0.01) and caused a significant regression in atherosclerotic plaques in aorta (66 ± 6 μm(2) vs 37 ± 1 μm(2); scrmb vs. Nox2ds-tat; P < 0.001). Increased VEGF, HIF-1α, MMP-9 and visfatin expression in arterial tissue in response to high-fat diet were significantly attenuated by Nox2ds-tat which in turn impaired both MMP-9 protein expression and activity.

Conclusion: Given these results, it is quite evident that selective Nox inhibitors can reverse vascular pathology arising with atherosclerosis.

Keywords: Oxidative stress; Vascular Nox; Vulnerable plaque.