An oxidized derivative of cholesterol increases the release of soluble vascular cell adhesion molecule-1 from human umbilical vein endothelial cells in culture

Inflammation-related gene expression by lipid oxidation-derived products in the progression of atherosclerosis

Vascular areas of atherosclerotic development persist in a state of inflammation, and any further inflammatory stimulus in the subintimal area elicits a proatherogenic response; this alters the behavior of the artery wall cells and recruits further inflammatory cells. In association with the inflammatory response, oxidative events are also involved in the development of atherosclerotic plaques. It is now unanimously recognized that lipid oxidation-derived products are key players in the initiation and progression of atherosclerotic lesions. Oxidized lipids, derived from oxidatively modified low-density lipoproteins (LDLs), which accumulate in the intima, strongly modulate inflammation-related gene expression, through involvement of various signaling pathways. In addition, considerable evidence supports a proatherogenic role of a large group of potent bioactive lipids called eicosanoids, which derive from oxidation of arachidonic acid, a component of membrane phospholipids. Of note, LDL lipid oxidation products might regulate eicosanoid production, modulating the enzymatic degradation of arachidonic acid by cyclooxygenases and lipoxygenases; these enzymes might also directly contribute to LDL oxidation. This review provides a comprehensive overview of current knowledge on signal transduction pathways and inflammatory gene expression, modulated by lipid oxidation-derived products, in the progression of atherosclerosis.

Endogenous prostaglandin D2 synthesis decreases vascular cell adhesion molecule-1 expression in human umbilical vein endothelial cells

We examined the role of prostaglandin D(2) (PGD(2)) in the expression of vascular cell adhesion molecule-1 (VCAM)-1 following interleukin-1beta (IL-1) stimulation in human umbilical vein endothelial cells (HUVEC) transfected with lipocaline-type PGD(2) synthase (L-PGDS) genes. HUVEC were isolated from human umbilical vein and incubated with 20 U/ml IL-1 and various concentrations of authentic PGD(2). The isolated HUVEC were also transfected with L-PGDS genes by electroporation. The L-PGDS-transfected HUVEC were used to investigate the role of endogenous PGD(2) in IL-1-stimulated VCAM-1 biosynthesis. We also used an anti-PGD(2) antibody to examine whether an intracrine mechanism was involved in VCAM-1 production. PGD(2) and VCAM-1 levels were determined by radio- and cell surface enzyme-immunoassay, respectively. VCAM-1 mRNA was assessed by RT-PCR. IL-1-stimulated VCAM-1 expression by HUVEC was dose-dependently inhibited by authentic PGD(2). L-PGDS gene-transfected HUVEC produced more PGD(2) than HUVEC transfected with the reporter gene alone. IL-1 induced increases in VCAM-1 expression in HUVEC transfected with reporter genes alone. However, this effect was significantly attenuated in the case of IL-1 stimulation of HUVEC transfected with L-PGDS genes, and accompanied by an apparent suppression of VCAM-1 mRNA expression. Neutralization of extracellular PGD(2) by anti-PGD(2)-specific antibody influenced neither VCAM-1 mRNA expression nor VCAM-1 biosynthesis. In conclusion, HUVEC transfected with L-PGDS genes showed increased PGD(2) synthesis. This increase was associated with attenuation of both VCAM-1 expression and VCAM-1 mRNA expression. The results suggest that endogenous PGD(2) decreases VCAM-1 expression and VCAM-1 mRNA expression, probably through an intracrine mechanism.

7-Ketocholesterol enhances the expression of adhesion molecules on human aortic endothelial cells by increasing the production of reactive oxygen species

The aim of the present study was to assess the expression of intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), monocytic adhesion of human aortic endothelial cells (HAECs), and the production of intracellular reactive oxygen species (ROS), when HAECs were stimulated by 7-ketocholesterol. 7-ketocholesterol enhances surface expression of ICAM-1 and VCAM-1 as determined by EIA, induces their mRNA expression by RT-PCR, and stimulates adhesiveness of HAECs to U937 monocytic cells. We confirmed up-regulation of ROS production of HAECs treated with 7-ketocholesterol. Although the surface expression of ICAM-1 and VCAM-1 on HAECs treated with 7-ketocholesterol increased in a time-dependent manner, alpha-tocopherol inhibited this increase of the surface expression of ICAM-1 and VCAM-1. In the monocytic adhesion assay, adhesion of U937 to HAECs treated with 7-ketocholesterol was enhanced, but monoclonal anti-ICAM-1 and VCAM-1 antibodies reduced the endothelial adhesiveness. In conclusion, this study suggests that the endothelial adhesiveness to monocytic cells that was increased by 7-ketocholesterol was associated with enhanced expression of ICAM-1 and VCAM-1 mediated by ROS production.

Effects of Fluvastatin in Type 2 Diabetic Patients with Hyperlipidemia: Reduction in Cholesterol Oxidation Products and VCAM-1

The purpose of this study was to investigate the lipid-lowering and anti-oxidative effects of fluvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, in type 2 diabetic patients. Six patients (3 men and 3 women, mean age = 56.2) took 20 mg of fluvastatin once daily (at night) for 12 weeks. Several markers of oxidative stress were then measured in these patients including plasma cholesterol oxidation products, i.e. oxysterols, and the levels of circulating adhesion molecules. Plasma total cholesterol levels were reduced by 12.3% in these individuals after 4 weeks of treatment, with levels remaining below 220 mg/dl for the entire treatment period. LDL levels were significantly reduced at 4 (18.1%) and 12 weeks (16.1%), and triglyceride levels were significantly reduced after 8 (22.5%) and 12 (37.7%) weeks of treatment. HDL-C levels increased from 50.7 +/- 15.4 prior to treatment to 63.8 +/- 24.3 mg/dl after 12 weeks of treatment, though this increase was not statistically significant. Lipid hydroperoxide, thiobarbituric acid-reactive substance (TBARS), and oxysterol levels were also reduced, suggesting that fluvastatin also had anti-oxidative effects. Finally, VCAM-1 levels were similarly reduced by fluvastatin treatment. We conclude that fluvastatin safely improves the plasma lipid profile in type 2 diabetic patients with hyperlipidemia. We speculate that this drug might be doubly effective in reducing atherosclerosis and cardiac events in these patients as a result of its demonstrated anti-oxidative effects and its ability to reduce VCAM-1 levels.