15-hydroxy-5-8-11-13-eicosatetraenoic-acid and Arteriosclerosis

The development of atherosclerosis is accelerated in individuals with type 2 diabetes. Adhesion of monocytes to the vascular endothelium is a key initial step in atherogenesis. We have previously shown that monocyte adhesion to human aortic endothelial cells (HAECs) cultured long-term in high-glucose medium (25 mmol/L, 2 passages) is increased compared with cells grown in normal glucose (5 mmol/L). One potential mechanism for increased monocyte adhesion to HAECs under hyperglycemic conditions is via the 12-lipoxygenase (12-LO) pathway. In this study, we demonstrated in HAECs that the major LO metabolite of arachidonic acid was the 12-LO product, 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], which was increased severalfold in HAECs cultured under high-glucose conditions. Furthermore, treatment of HAECs with 12(S)-HETE induced monocyte, but not neutrophil, adhesion an average of 3-fold (range of 1.5- to 5-fold) compared with untreated cells (75+/-5 versus 26+/-1 monocytes per field, respectively, P<0.001). Expression of the adhesion molecules vascular cell adhesion molecule-1, E-selectin, and intercellular adhesion molecule-1 was not significantly increased. However, both glucose and 12(S)-HETE induced a 60% increase in HAEC surface expression of connecting segment-1 (ie, CS-1) fibronectin, a ligand for very late-acting antigen-4 (VLA-4). The antibodies used to block monocyte integrin VLA-4 and leukocyte function-related antigen-1, a monocytic counterreceptor for intercellular adhesion molecule-1, inhibited the ability of both 12-LO products and high glucose to induce monocyte adhesion. These results definitively demonstrate for the first time in HAECs that the 12-LO pathway can induce monocyte-endothelial cell interaction and that the effects of glucose may be mediated, at least in part, through this pathway. Thus, these results suggest that the 12-LO pathway may play a role in the increased susceptibility of diabetics to atherosclerosis.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Antibodies, Blocking; Antigens, CD; Aorta; Arteriosclerosis; CD18 Antigens; Cell Adhesion; Cells, Cultured; E-Selectin; Endothelium, Vascular; Glucose; Humans; Hydroxyeicosatetraenoic Acids; Hyperglycemia; Integrin alpha4; Intercellular Adhesion Molecule-1; Lipoxygenase; Monocytes; Neutrophils; Vascular Cell Adhesion Molecule-1

In summary, we suggest that hyperglycemia causes upregulation of 12-lipoxygenase activity. The increased production of 12-LO products, 12(S) and 15(S)-HETE, activates monocyte integrins which result in enhanced adhesion of monocytes to endothelium. The binding of monocytes to endothelium is a key early event in development of atherosclerosis. Upregulation of this process by vascular cells exposed to chronic elevations in glucose may be one explanation for the accelerated atherosclerosis observed in patients with Type 2 diabetes.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonate 12-Lipoxygenase; Arteriosclerosis; Cell Adhesion; Cell Communication; Cells, Cultured; Diabetic Angiopathies; Endothelium, Vascular; Glucose; Humans; Hydroxyeicosatetraenoic Acids; Hyperglycemia; Lipoxygenase Inhibitors; Monocytes; Signal Transduction

The lipoxygenase product 15-hydroxyeicosatetraenoic acid (15-HETE) was shown to be the most important eicosanoid formed in the atherosclerotic rabbit aorta. The aim of the present study was to compare the effects of 15-HETE and its hydroperoxy precursor 15-HpETE with those of other vasoconstrictor and vasodilator agents in arteries from rabbits fed either a control or a cholesterol-rich diet for 16 and 30 weeks. 5-Hydroxytryptamine (5-HT) aggregated platelets and thrombin caused contractions of isolated rabbit aortas. The contractile responses elicited by platelets from control animals were similar to those evoked by platelets from atherosclerotic rabbits. After 16 weeks of hypercholesterolemia, the contractile responses were either augmented (5-HT), unchanged (platelets) or reduced (thrombin). After 30 weeks of hypercholesterolemia, the responses to all contractile agents used had decreased. In both aortas and pulmonary arteries the endothelium-dependent relaxations to the calcium ionophore, A23167, and to acetylcholine were progressively lost and the endothelium-independent relaxations to nitroglycerin were reduced by the progressing hypercholesterolemia. The 15-lipoxygenase metabolites contracted the isolated thoracic aorta and pulmonary artery from control rabbits and to a lesser extent those of the cholesterol-fed rabbits. After raising the tone in these vessels with prostaglandin F2 alpha PGF2 alpha) or noradrenaline, 15-HpETE induced relaxations which were not significantly influenced by the development of fatty streaks. Our data illustrate that the contractions of the blood vessel wall to 15-HETE, like those to other vasoconstrictors, are markedly reduced by developing atherosclerosis. In contrast, the relaxations to 15-HpETE in the rabbit arteries remain unaltered after 16 to 30 weeks of hypercholesterolemia. This is unlike the reactions to other vasodilators, which are markedly reduced.

Topics: Acetylcholine; Animals; Arachidonate 15-Lipoxygenase; Arteriosclerosis; Calcimycin; Dinoprost; Hydroxyeicosatetraenoic Acids; Hypercholesterolemia; In Vitro Techniques; Leukotrienes; Lipid Peroxides; Male; Muscle, Smooth, Vascular; Nitroglycerin; Platelet Aggregation; Rabbits; Thrombin; Vasoconstrictor Agents; Vasodilator Agents

The content of 13-hydroxylinoleic acid (13-HODE) and 15-hydroxyarachidonic acid (15-HETE) in the rabbit thoracic aorta was measured using high performance liquid chromatography after chronic exposure to cholesterol and a high dose of molsidomine, a donor of nitric oxide (NO). Cholesterol-induced fatty streak formation was accompanied by a decrease in the amounts of esterified 13-HODE and 15-HETE. The reduction of the esterified 13-HODE content correlated significantly with the severity of the lesions. These results do not support the hypothesis that fatty acid hydroperoxides accumulate in the arterial wall during atherosclerosis. On the other hand, the quantity of esterified 13-HODE and 15-HETE was increased markedly after exposure to molsidomine. The high dose of this agent could have initiated radical reactions (via liberation of NO and production of superoxide anions) thereby leading to a raise of the 13-HODE and 15-HETE content of the vessel.

Topics: Animals; Aorta, Thoracic; Arteriosclerosis; Cholesterol; Chromatography, High Pressure Liquid; Hydroxyeicosatetraenoic Acids; Linoleic Acids; Male; Molsidomine; Nitrogen Oxides; Rabbits; Superoxides; Triglycerides

Atherosclerotic plaque formation is accompanied by hyperproliferative events which have many features of an inflammatory response. A high-performance liquid chromatography procedure was developed to analyze the inflammatory prostaglandins, leukotrienes and hydroxyeicosatetraenoic acids (HETEs) produced by aortic segments. Normal rabbit aortas incubated with tritiated arachidonic acid synthesized 12-HETE as the principal lipoxygenase metabolite, and prostacyclin as the major cyclooxygenase product. In contrast, atherosclerotic aortas from both cholesterol-fed and Watanabe Heritable Hyperlipidemic rabbits showed major increases in synthesis of lipoxygenase-derived 15-HETE, which became the predominant eicosanoid in the aortas of both types of rabbit. No leukotrienes or other 5-lipoxygenase products were detected to the detection limit of 0.5 pmol/cm aorta. 15-HETE, which is chemotactic for smooth muscle cells, mitogenic for endothelial cells, and an inhibitor of prostacyclin synthesis may thus play a role in atherogenesis.

Topics: Animals; Aorta; Arteriosclerosis; Cholesterol; Disease Models, Animal; Hydroxyeicosatetraenoic Acids; Hyperlipidemias; Lipoxygenase; Male; Rabbits

Mammalian tissues contain 5-, 12- and 15-lipoxygenases. Only the 15-lipoxygenase can act on linoleic acid, the predominant essential fatty acid of tissues and plasma, producing 13-hydroxyoctadecadienoic acid (13-HODE). Intracellular production of 13-HODE renders endothelial cells resistant to platelet adhesion, while its hydroperoxy precursor, 13-HPODE, synergises with the platelet anti-aggregatory factor prostacyclin. We have found that a 15-lipoxygenase activity is induced in aortas of cholesterol-fed and Watanabe Heritable Hyperlipidemic (WHHL) rabbits. Aortic tissue from WHHL rabbits incubated with 3H-linoleic acid produced a major metabolite identified as 13-HODE, which was formed with an efficiency comparable to the synthesis 15-HETE from arachidonic acid. These findings indicate that the increased aortic 15-lipoxygenase in vascular tissue is capable of producing 13-HODE in vivo. Since platelet adhesion is increased in atherogenesis, and thrombogenesis is a major complication of advanced atherosclerosis, it is suggested that induction of this enzyme may be a protective response to hypercholesterolemia.

Topics: Animals; Antithrombins; Aorta; Arachidonate 15-Lipoxygenase; Arachidonate Lipoxygenases; Arachidonic Acids; Arteriosclerosis; Calcimycin; Chromatography, High Pressure Liquid; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Linoleic Acids; Rabbits

The metabolism of arachidonic acid by cholesterol-enriched resident mouse peritoneal macrophages was investigated. The amounts of monohydroxyeicosatetraenoic acid (mono-HETE) produced by the cholesterol-rich macrophages were 2.5-fold greater when compared to control macrophages. The major lipoxygenase product, identified by high-performance liquid chromatography in both macrophages was 12-HETE. Since macrophages are important participants in the formation of atheromatous lesions, the increased metabolism of arachidonic acid to HETE products by cholesterol-rich macrophages could contribute to the initiation and progression of the atherosclerotic process.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Arachidonic Acids; Arteriosclerosis; Cells, Cultured; Cholesterol; Chromatography, Thin Layer; Cyclooxygenase Inhibitors; Hydroxyeicosatetraenoic Acids; Ibuprofen; Indomethacin; Lipoxygenase; Macrophages; Male; Mice

Atherosclerosis was induced in New Zealand White rabbits through cholesterol feeding. Aortae were taken out from treated animals and incubated with arachidonic acid. Aortae from cholesterol-fed animals converted arachidonic acid into 15-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE). This conversion was not seen in aortae from control animals. The immediate precursor of 15-HETE, 15-HPETE, is an inhibitor of prostacyclin synthetase and might hamper prostacyclin production.

Topics: Animals; Aorta; Arachidonic Acids; Arteriosclerosis; Cholesterol, Dietary; Hydroxyeicosatetraenoic Acids; Isomerism; Male; Rabbits