Overexpression of antioxidant enzymes in ApoE-deficient mice suppresses Benzo(a)pyrene-accelerated atherosclerosis

Abstract

The carcinogenic polycylic aromatic hydrocarbon, benzo(a)pyrene (BaP), has been shown to generate reactive oxygen species (ROS) and accelerate the development of atherosclerosis. To assess the causal role of BaP-generated ROS in this process, we evaluated atherosclerotic metrics in apolipoprotein E-deficient (ApoE-/-) mice with or without overexpression of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and/or catalase. Without BaP, aortic atherosclerotic lesions were smaller in ApoE-/- mice overexpressing catalase or both Cu/Zn-SOD and catalase than in those overexpressing neither or Cu/Zn-SOD only. After treating with BaP or vehicle for 24 weeks, mean lesion sizes in the aortic tree and aortic root of ApoE-/- mice were increased by approximately 60% and 40%, respectively. BaP also increased the levels of oxidized lipids in the aortic tree of ApoE-/- mice and increased the frequency of advanced lesions. In contrast, BaP did not significantly alter lipid peroxidation levels or atherosclerotic lesions in the aortas of ApoE-/- mice overexpressing Cu/Zn-SOD and/or catalase. Overexpression of Cu/Zn-SOD and/or catalase also inhibited BaP-induced expression of cell adhesion molecules in aortas and endothelial cells, and reduced BaP-induced monocyte adhesion to endothelial cells. These observations, together with the functions of catalase and Cu/Zn-SOD to scavenge hydrogen peroxide and superoxide anions, implicate a causal role of ROS in the pathogenesis of BaP-induced atherosclerosis.

Improvements of Atherosclerosis and Hepatic Oxidative Stress are Independent of Exercise Intensity in LDLr^-/- Mice

“…For example, SOD overexpression along with CAT decreased Benzo[a]pyrene-induced atherosclerosis in ApoE −/− mice 34) . It was suggested that increased SOD may reduce atherosclerosis through the co-activation of vascular relaxation mediated by nitric oxide (NO) as the radical O2 dismutation increases the bioavailability of NO in endothelial cells; in the presence of the O2 radical, NO shifts to the formation of peroxide nitrite 34) . The aerobic exercise protocol employed in the present study increased CAT activity.…”

“…In agreement, Fukao et al 31) demonstrated that voluntary exercise decreases atherosclerosis with no change in TC and TG serum levels. It is noteworthy that in ApoE −/− mice the decrease in the atherosclerotic lesion induced by Benzo(a)pyrene may occur with no changes in TC and TG serum levels 34) . Serum levels of TG normally decrease in response to aerobic exercise when a normal chow diet is used.…”

Enzymatic Targets in Atherosclerosis

“…The sooner pitfalls and misinterpretations will be detected, the better both for the benefit of people and to reduce the economic burden associated with death endclinical trials. Lp-PLA2 (-) Inhibition by RNAi [101] and selective inhibitors [102,103] reduced lipid accumulation and progression of coronary atherosclerosis in various atherogenic experimental models PCSK9 (-) Inhibition by alirocumarib reduced LDL levels [1] Oxidative stress related enzymes NADPH oxidase (-) NOX1/4 inhibitor GKT136901 reduced ROS [119,120]; NOX1/2 inhibitor apocynin reduced aortic lesions in apoE-/-LDLR-/-mice [121] Nitric Oxide Synthase (+) Adenovirus-mediated iNOS gene transfer studies showed that local NO synthesis induced significant proliferation of SMCs and intimal hyperplasia in rats [135] Superoxide dismutases (+) SOD local delivery decreased the cuff-induced arterial neointima [138], accelerated endothelial recovery and inhibited in-stent restenosis in the aorta of Watanabe rabbits [139]; mitochondrial SOD protected apoE-/-mice against atherosclerosis [140,141] Catalases (+) Overexpression retarded atherosclerosis development in apoE-/-mice [141]; dietary supplements upregulated CAT expression in apoE-/-mice and reduced atherosclerosis [144,145]; CAT attenuated non-dietary atherosclerosis in apoE-/-mice [146] Glutathione peroxidases (+) Mimetic diphenyl diselenide reduced atherosclerotic lesions in LDLR-/-mice [153] Heme oxygenase-1 (+) Inducers hemin±desferrioxamine reduced atherosclerotic lesions in LDLR-/-mice [164] Paraoxonases (+) Reduced protein N-homocysteinylation, prevented accumulation of oxLDL, promoted cholesterol efflux from macrophages [173], improved endothelial function [174] Vascular remodeling related enzymes Matrix Metalloproteases (-)/(+) Area of aortic calcified lesions was reduced in apoE-/-/MMP2-/-mice compared to apoE-/-mice ( [192]); apoE-/-/MMP-3-/-and apoE-/-/MMP-9-/-mice had larger brachiocephalic artery plaques [193], while lesion size was reduced in apoE-/-/MMP-12-/-mice [193] Inflammation related enzymes Cyclooxygenase (-) COX-1 knockout in apoE-/-mice reduced platelet-vascular wall interactions and decreased lesions [203] Lipoxygenase (-) 12/15 LO knockout in macrophages impaired oxLDL-induced foam cell formation and endothelial activation …”

“…CAT is also powerful in the attenuation of non-dietary atherosclerosis in apoE-deficient mice. Thus, its overexpression in apoE mice exposed to the polycyclic aromatic hydrocarbon benzopyrene, alone or in association with Cu/Zn-SOD, led to increased protection as compared with those overexpressing only Cu/Zn-SOD [146].…”

Oxidative stress in carotid arteries of patients submitted to carotid endarterectomy. The role of aging process

“…By converting hydrogen peroxide into water, CAT constitutes a primary antioxidant defense system and could protect cells from ROS and its deleterious consequences 31 . In experimental setting, CAT leads to a delayed onset of atherosclerosis in a murine model 32 . Besides, longer-liver mice have more abundant expression of CAT in aortas when compared to shorter-lived mice, but expression of SOD was similar in both groups 10 .…”