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Oxidized LDLs influence thrombotic response and cyclooxygenase 2.
1Department of Pharmacological Sciences, University of Milan, Milan, Italy.
Prostaglandins, Leukotrienes, and Essential Fatty Acids
|September 27, 2002
Summary
Oxidized LDLs (oxLDLs) promote atherosclerosis by disrupting endothelial cells and altering the inflammatory response in macrophages. Specific oxidized phospholipids, like Ox-PAPC, may be responsible for these effects, potentially attenuating inflammation during atherogenesis.
Area of Science:
- Biochemistry
- Cardiovascular Biology
- Immunology
Background:
- Oxidative modification of low-density lipoproteins (LDLs) is a critical factor in atherosclerosis and coronary artery disease development.
- LDL oxidation disrupts the antithrombotic balance in endothelial cells, increasing tissue factor (TF) activity and fibrin deposition.
- Fibrinolysis is dysregulated by LDL oxidation, with increased inhibition rates due to altered plasminogen activator inhibitor-1 (PAL-1) and tissue-type plasminogen activator (tPA) activity.
Purpose of the Study:
- To investigate the impact of oxidized LDLs (oxLDLs) on endothelial cell function and macrophage inflammatory responses.
- To explore the role of specific oxidized lipids, such as Ox-PAPC, in mediating the biological activities of oxLDLs.
- To understand how oxLDLs influence the inflammatory milieu within atheromata and contribute to atherogenesis.
Main Methods:
- Analysis of endothelial cell responses to LDL oxidation, focusing on tissue factor pathway activity and fibrin deposition.
- Assessment of fibrinolysis regulation by monitoring PAL-1 and tPA activity under oxLDL influence.
- Evaluation of macrophage inflammatory markers, specifically inducible cyclooxygenase (Cox-2) expression, in response to oxLDLs and bacterial lipopolysaccharide.
- Investigation of the effects of Ox-PAPC, a component of oxLDLs, on Cox-2 expression in macrophages.
Main Results:
- Oxidation of LDLs alters endothelial cell antithrombotic balance, promoting TF pathway activity and fibrin deposition.
- LDL oxidation dysregulates fibrinolysis, leading to increased inhibition.
- OxLDLs downregulate Cox-2 expression in macrophages stimulated with lipopolysaccharide.
- Ox-PAPC, a component of oxLDLs, was identified as a potential mediator preventing Cox-2 expression.
Conclusions:
- Oxidative modification of LDLs contributes to atherogenesis through endothelial dysfunction and altered inflammatory responses in macrophages.
- The observed downregulation of Cox-2 by oxLDLs in macrophages suggests a potential attenuation of the inflammatory response within atheromata.
- Oxidized phospholipids, specifically Ox-PAPC, may be responsible for the anti-inflammatory effects of oxLDLs, influencing macrophage behavior and potentially contributing to athrogenesis progression.