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Oxidized LDL and HDL: antagonists in atherothrombosis
1Center for Experimental Surgery and Anesthesiology, Katholieke Universiteit Leuven, Belgium.
Insights
Oxidized LDL (low-density lipoprotein) significantly increases coronary artery disease risk. High-density lipoprotein (HDL) cholesterol protects against atherosclerosis by counteracting oxidized LDL
Area of Science:
- Cardiovascular Science
- Lipid Metabolism
- Atherosclerosis Research
Background:
- Increased low-density lipoprotein (LDL) oxidation is a key factor in coronary artery disease (CAD) development.
- Circulating oxidized LDL offers predictive value for cardiovascular risk beyond traditional scores.
- Oxidized LDL originates from mild arterial wall oxidation, not extensive blood oxidation.
Purpose of the Study:
- To investigate the role of oxidized LDL in cardiovascular disease pathogenesis.
- To explore the antagonistic relationship between oxidized LDL and high-density lipoprotein (HDL) cholesterol in atherosclerosis.
- To elucidate the mechanisms by which oxidized LDL promotes and HDL protects against atherosclerosis.
Main Methods:
- Analysis of circulating oxidized LDL levels and their correlation with cardiovascular risk factors.
- Investigation of oxidized LDL's effects on endothelial cells, smooth muscle cells, and macrophages.
- Evaluation of HDL's protective mechanisms, including enzyme activity (paraoxonase, PAF-acetyl hydrolase) and inhibition of oxidized LDL effects.
Main Results:
- Oxidized LDL promotes atherosclerosis by stimulating monocyte infiltration, smooth muscle cell proliferation, and endothelial cell apoptosis.
- Oxidized LDL contributes to atherothrombosis by disrupting endothelial anticoagulant balance and promoting pro-thrombotic factors.
- HDL cholesterol levels are inversely associated with CAD risk, with HDL actively preventing monocyte infiltration and protecting against oxidized LDL's detrimental effects.
Conclusions:
- Oxidized LDL and HDL cholesterol are critical antagonists in cardiovascular disease development.
- HDL-associated enzymes like paraoxonase and PAF-acetyl hydrolase play crucial roles in preventing atherosclerosis.
- Targeting oxidized LDL and enhancing HDL function represent potential therapeutic strategies for cardiovascular disease.
Abstract:
Increased LDL oxidation is associated with coronary artery disease. The predictive value of circulating oxidized LDL is additive to the Global Risk Assessment Score for cardiovascular risk prediction based on age, gender, total and HDL cholesterol, diabetes, hypertension, and smoking. Circulating oxidized LDL does not originate from extensive metal ion-induced oxidation in the blood but from mild oxidation in the arterial wall by cell-associated lipoxygenase and/or myeloperoxidase. Oxidized LDL induces atherosclerosis by stimulating monocyte infiltration and smooth muscle cell migration and proliferation. It contributes to atherothrombosis by inducing endothelial cell apoptosis, and thus plaque erosion, by impairing the anticoagulant balance in endothelium, stimulating tissue factor production by smooth muscle cells, and inducing apoptosis in macrophages. HDL cholesterol levels are inversely related to risk of coronary artery disease. HDL prevents atherosclerosis by reverting the stimulatory effect of oxidized LDL on monocyte infiltration. The HDL-associated enzyme paraoxonase inhibits the oxidation of LDL. PAF-acetyl hydrolase, which circulates in association with HDL and is produced in the arterial wall by macrophages, degrades bioactive oxidized phospholipids. Both enzymes actively protect hypercholesterolemic mice against atherosclerosis. Oxidized LDL inhibits these enzymes. Thus, oxidized LDL and HDL are indeed antagonists in the development of cardiovascular disease.