The relationship of hydroxyeicosatetraenoic acids and F2-isoprostanes to plaque instability in human carotid atherosclerosis

Abstract

Evidence for increased oxidant stress has been reported in human atherosclerosis. However, no information is available about the importance of in situ oxidant stress in relation to plaque stability. This information is relevant because the morbidity and mortality of atherosclerosis are essentially the consequences of acute ischemic syndromes due to unstable plaques. We studied 30 carotid atherosclerotic plaques retrieved by endarterectomy from 18 asymptomatic (stable plaques) and 12 symptomatic patients (unstable plaques). Four normal arteries served as controls. After lipid extraction and ester hydrolysis, quantitation of different indices of oxidant stress were analyzed, including hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatetraenoic acids (EETs), ketoeicosatetraenoic acids (oxoETEs), and F 2 -isoprostanes using online reverse-phase high-performance liquid chromatography tandem mass spectrometry (LC/MS/MS). All measurements were carried out in a strictly double-blind procedure. We found elevated levels of the different compounds in atherosclerotic plaques. Levels of HETEs were 24 times higher than EETs, oxo-ETEs, or F 2 -isoprostanes. Levels of HETEs, but not those of EETs, oxo-ETEs or F 2 -isoprostanes, were significantly elevated in plaques retrieved from symptomatic patients compared with those retrieved from asymptomatic patients (1,738 ± 274 vs. 1,002 ± 107 pmol/µmol lipid phosphorous, respectively; P < 0.01). One monooxygenated arachidonate species, 9-HETE, which cannot be derived from known enzymatic reactions, was the most abundant and significant compound observed in plaques, suggesting that nonenzymatic lipid peroxidation predominates in advanced atherosclerosis and may promote plaque instability.

Systemic elevations of free radical oxidation products of arachidonic acid are associated with angiographic evidence of coronary artery disease

“…Remarkably, studies examining lipid oxidation species within excised human atheroma from symptomatic versus nonsymptomatic carotid endarterectomy specimens identified 9-HETE, and less so F 2 -Isoprostane, as abundant fatty acid oxidation products within atheroma from symptomatic vascular lesions [34]. Other studies have documented the presence of F 2 -Isoprostane as lipid oxidation products enriched within atheroma [32].…”

Disease Stage-Dependent Accumulation of Lipid and Protein Oxidation Products in Human Atherosclerosis

“…The former are the major lipid oxidation products formed when lipoproteins undergo in vitro oxidation and contribute to the in vitro formation of high-uptake LDL. 7 In addition, CE-O(O)H are the major lipid oxidation products in human lesions 1,12,26,31 and hydroxylated fatty acids are associated with plaque instability. 31 Notably, CE-O(O)H and oxysterols are not found in normal iliac arteries 12,32 or in circulating plasma lipoproteins.…”

“…7 In addition, CE-O(O)H are the major lipid oxidation products in human lesions 1,12,26,31 and hydroxylated fatty acids are associated with plaque instability. 31 Notably, CE-O(O)H and oxysterols are not found in normal iliac arteries 12,32 or in circulating plasma lipoproteins. 13 Our data show a disease stage-dependent increase in intimal CE-O(O)H (Table 2) suggesting that overall CE-O(O)H is a suitable parameter to monitor the extent of lipoprotein lipid oxidation in the vessel wall.…”

“…39 Consistent with this, isoprostane levels in atherosclerotic lesions are 20-fold to 300-fold lower per parent molecule than lipid hydroxides. 31 Like isoprostanes, oxovaleroyl and glutaroyl are generated from arachidonic acid-containing phospholipids, most likely via fragmentation of arachidonic acid hydroperoxides, a process that is inhibited strongly in the presence of ␣-TOH. 40 Indeed, the generation of fragments of polyunsaturated fatty acids is almost completely prevented during LDL oxidation as long as ␣-TOH remains present.…”

Cytosolic Phospholipase A2 Is an Effector of Jak/STAT Signaling and Is Involved in Platelet-derived Growth Factor BB-induced Growth in Vascular Smooth Muscle Cells

“…A variety of molecules (including peptide growth factors, hormones, eicosanoids, and oxidants) that are generated at the site of arterial injury and/or inflammation can influence the growth and migration of VSMC (1)(2)(3)(4)(5)(6). Indeed, increased levels of growth factors such as platelet-derived growth factor, eicosanoids such as hydroxyeicosatetraenoic acids, and oxidants such as oxidized low density lipoprotein have been reported in atheromatous arteries compared with normal arteries (3)(4)(5)(6)(7)(8)(9). As these molecules utilize divergent early mitogenic signaling events in the induction of VSMC growth (10,11), targeting inhibition of the activity of a single mitogen might not be able to suppress VSMC growth and lesion formation.…”