8-11-14-eicosatrienoic-acid and 15-hydroxy-5-8-11-13-eicosatetraenoic-acid

Lipoxygenase, cyclo-oxygenase and cytochrome P450 (CYP) products of arachidonic acid (AA) are implicated in pulmonary vasoregulation. The CYP-mediated epoxyeicosatrienoates (EETs) have been described previously as the predominant eicosanoids in human lungs upon stimulation with the Ca(2+) ionophore A23187. In this study, we challenged perfused human lungs with two microbial agents: Escherichia coli haemolysin (ECH) and formyl-methionyl-leucyl-phenylalanine (fMLP). Both stimuli elicited pronounced generation of leukotrienes (LTs), hydroxyeicosatetraenoic acids (HETEs), prostanoids (PTs) and EETs/dihydroxyeicosatrienoic acids (DHETs), as assessed by liquid chromatography-mass spectrometry, paralleled by pulmonary artery pressor response and lung oedema formation. The maximum buffer concentrations of EETs/DHETs surpassed those of LTs plus HETEs and PTs by a factor of four (ECH) or three (AA/fMLP). Dual 5-lipoxygenase/cyclo-oxygenase inhibition caused pronounced reduction of AA/fMLP-induced LT/PT synthesis and oedema formation but only limited attenuation of pulmonary vasoconstriction, while inhibition of CYP epoxygenase clearly attenuated AA/fMLP-induced EET/DHET synthesis and vasoconstriction but not oedema formation, suggesting a major contribution of LTs/PTs to vascular leakage and of EETs/DHETs to pressor response. Consequently, generation of EETs/DHETs is greater than that of LTs plus HETEs and PTs in ex vivo perfused human lungs upon microbial challenge suggesting a substantial contribution of these mediators to inflammatory-infectious pulmonary injury.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acid; Capillary Permeability; Cytochrome P-450 Enzyme System; Eicosanoids; Epoxide Hydrolases; Escherichia coli Proteins; Hemolysin Proteins; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Leukotriene E4; Lipoxygenase; Lung; N-Formylmethionine Leucyl-Phenylalanine; Perfusion; Prostaglandins; Pulmonary Circulation; Rabbits; Vasoconstriction

To determine in vivo if L-4F differentially alters plasma levels of oxidized fatty acids resulting in more anti-inflammatory HDL. Injecting L-4F into apoE null mice resulted in a significant reduction in plasma levels of 15-HETE, 5-HETE, 13-HODE and 9-HODE. In contrast, plasma levels of 20-HETE were not reduced and plasma levels of 14,15-EET, which are derived from the cytochrome P450 pathway, were elevated after injection of L-4F. Injection of 13(S)-HPODE into wild-type C57BL/6J mice caused an increase in plasma levels of 13-HODE and 9-HODE and was accompanied by a significant loss in the anti-inflammatory properties of HDL. The response of atherosclerosis resistant C3H/HeJ mice to injection of 13(S)-HPODE was similar but much more blunted. Injection of L-4F at a site different from that at which the 13(S)-HPODE was injected resulted in significantly lower plasma levels of 13-HODE and 9-HODE and significantly less loss of HDL anti-inflammatory properties in both strains. i) L-4F differentially alters plasma levels of oxidized fatty acids in vivo. ii) The resistance of the C3H/HeJ strain to atherosclerosis may in part be mediated by a reduced reaction of this strain to these potent lipid oxidants.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Anti-Inflammatory Agents; Apolipoproteins E; Atherosclerosis; Chromatography, Liquid; Enzyme-Linked Immunosorbent Assay; Fatty Acids; Female; Hydroxyeicosatetraenoic Acids; Injections, Subcutaneous; Linoleic Acids; Linoleic Acids, Conjugated; Lipid Peroxides; Lipoproteins, HDL; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Knockout; Oxidation-Reduction; Peptides; Species Specificity; Tandem Mass Spectrometry; Time Factors; Up-Regulation

Endothelium-dependent vasorelaxation of the rabbit aorta is mediated by either nitric oxide (NO) or arachidonic acid (AA) metabolites from cyclooxygenase (COX) and 15-lipoxygenase (15-LO) pathways. 15-LO-1 metabolites of AA, 11,12,15-trihydroxyeicosatrienoic acid (THETA), and 15-hydroxy-11,12-epoxyeicosatrienoic acid (HEETA) cause concentration-dependent relaxation. We tested the hypothesis that in the 15-LO pathway of AA metabolism, 15-LO-1 is sufficient and is the rate-limiting step in inducing relaxations in rabbit aorta. Aorta and rabbit aortic endothelial cells were treated with adenoviruses containing human 15-LO-1 cDNA (Ad-15-LO-1) or beta-galactosidase (Ad-beta-Gal). Ad-15-LO-1-transduction increased the expression of a 75-kDa protein corresponding to 15-LO-1, detected by immunoblotting with an anti-human15-LO-1 antibody, and increased the production of HEETA and THETA from [(14)C]AA. Immunohistochemical studies on Ad-15-LO-1-transduced rabbit aorta showed the presence of 15-LO-1 in endothelial cells. Ad-15-LO-1-treated aortic rings showed enhanced relaxation to AA (max 31.7 +/- 3.2%) compared with Ad-beta-Gal-treated (max 12.7 +/- 3.2%) or control nontreated rings (max 13.1 +/- 1.6%) (P < 0.01). The relaxations in Ad-15-LO-1-treated aorta were blocked by the 15-LO inhibitor cinnamyl-3,4-dihydroxy-a-cyanocinnamate. Overexpression of 15-LO-1 in the rabbit aortic endothelium is sufficient to increase the production of the vasodilatory HEETA and THETA and enhance the relaxations to AA. This confirms the role of HEETA and THETA as endothelium-derived relaxing factors.

Topics: 8,11,14-Eicosatrienoic Acid; Adenoviridae; Animals; Aorta, Thoracic; Arachidonate 15-Lipoxygenase; Arachidonic Acid; Cells, Cultured; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Endothelial Cells; Genetic Vectors; Hydroxyeicosatetraenoic Acids; Immunohistochemistry; In Vitro Techniques; Lipoxygenase Inhibitors; Molecular Structure; Rabbits; Tandem Mass Spectrometry; Transduction, Genetic; Vasodilation; Vasodilator Agents

Topics: 8,11,14-Eicosatrienoic Acid; Arachidonate 12-Lipoxygenase; Aspirin; Blood Platelets; Humans; Hydroxyeicosatetraenoic Acids; Kinetics; Platelet Aggregation Inhibitors

Gammalinolenic acid (GLA), when provided as a dietary supplement, has been reported to improve clinical symptoms of several inflammatory disorders. The goal of the current study was to examine the metabolism of GLA and its relationship to arachidonic acid (AA) in the human neutrophil. Initial studies indicated that neutrophils provided GLA in vitro rapidly elongate it (by two carbons) to dihomogammalinolenic acid (DGLA). The bulk of this newly formed DGLA is incorporated into neutral lipids and specifically triacylglycerides. Neutrophils from volunteers supplemented with GLA as borage oil also had elevated quantities of DGLA but not GLA, when compared with neutrophils from volunteers not consuming the GLA supplement. To determine whether DGLA could be mobilized from cellular glycerolipids, neutrophils were stimulated with ionophore A23187 and fatty acid levels were determined. DGLA and AA were both released during stimulation, and the quantities of DGLA mobilized increased threefold after in vitro GLA supplementation. Exogenously provided DGLA was converted to one major metabolite during cell stimulation; this product migrated on reverse-phase HPLC with the 15-lipoxygenase product, 15-hydroxy-eicosa-trienoic acid (15-HETre). Both 15-HETre and DGLA (provided exogenously) inhibited the formation of leukotriene B4, (LTB4) and 20-hydroxy-leukotriene B4 (20-OH-LTB4). The IC50 for 15-HETre inhibition of both LTR, and 20-OH-LTB4 in A23187-stimulated neutrophils was 5 microM. This inhibition could be reversed by removing the compounds from the cells. Taken together, these data reveal that there are enzymes within the human neutrophil that metabolize GLA or its elongation product DGLA, and that the metabolism of GLA and AA may interact at a number of critical junctures.

Topics: 8,11,14-Eicosatrienoic Acid; Adult; Arachidonic Acid; gamma-Linolenic Acid; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Middle Aged; Neutrophil Activation; Neutrophils

We have previously demonstrated that rat epidermal microsomes NADPH-dependently convert 15(S)-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) into 15-hydroxy-5,8,11-eicosatrienoic acid (15-HETrE). The present study examines the mechanism of this reductive conversion. Rat epidermal microsomes were incubated with [1-14C]15-HPETE in the presence and absence of NADPH. Major reaction products were purified by high performance liquid chromatography (HPLC) and analyzed by gas chromatography-mass spectrometry (GC-MS), UV spectroscopy and/or cochromatography with standard products. In the presence of NADPH, 15-HPETE was transformed to 13-hydroxy-14,15-epoxy-5,8,11-eicosatrienoic acid (13-HEpETrE), 15(S)-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE), 15-keto-5,8,11-eicosatrienoic acid (15-KETrE) and 15-hydroxy-5,8,11-eicosatrienoic acid (15-HETrE). In the absence of NADPH, the microsomes reacted with 15-HPETE to form 13-HEpETrE, 15-keto-5,8,11,13-eicosatetraenoic acid (15-KETE) and 15-HETE. Furthermore, when supplemented with NADPH, epidermal microsomes converted 15-KETE to 15-KETrE, which was subsequently reduced to 15-HETrE. These data suggest that rat epidermal microsomes are capable of metabolizing 15-HPETE to 15-HETrE via the following reaction steps: conversion of HPETE to KETE, NADPH-dependent double bond saturation in KETE to KETrE and keto-reduction of the latter compound to HETrE.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Chromatography, High Pressure Liquid; Epidermis; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Leukotrienes; Lipid Peroxides; Microsomes; Rats; Rats, Wistar

The purpose of the present study was to determine the effect of the n-6 fatty acid, dihomogammalinolenic acid (DGLA, 20: 3, n-6) on arachidonic acid (AA) (C20: 4) metabolism by human peripheral mononuclear leukocytes (HPML). After incubation of HPML with A23187 (5 microM) and DGLA, the cyclooxygenase (CO) and lipoxygenase (LO) products were separated and quantified by reversed-phase high-performance liquid chromatography (RP-HPLC) combined with radioimmunoassay. DGLA led to no change in PGE2 formation, but at similar concentrations there was a dose-dependent decrease in LTB4 formation (IC50 = 45.0 microM). The inhibition of LTB4 formation by DGLA was associated with a dose-dependent increase in its 15-LO metabolite 15-hydroxyeicosatraenoic acid (15-HETrE) and its CO metabolite prostaglandin E1 (PGE1). Incubation of HPLM with 15-HETrE (0-1.5 microM) alone did not result in a change in PGE2 formation, whereas 15-HETrE was a much more potent inhibitor of LTB4 formation (IC50 = 0.5 microM) than DGLA. These results show that the addition of DGLA to HPML results in a selective inhibition of LTB4 formation, presumably via its metabolite (15-HETrE).

Topics: 8,11,14-Eicosatrienoic Acid; Dinoprostone; Eicosanoids; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Leukocytes, Mononuclear; Leukotriene B4; Lipoxygenase Inhibitors

Enzymatic transformation of the n-6 polyunsaturated fatty acid (PUFA) arachidonic acid (AA) by the 5-lipoxygenase (LO) enzyme results in the formation of leukotrienes (LTs) including leukotriene B4 (LTB4), which is a potent mediator of inflammation. The purpose of the present study was to determine the effect of other n-6 fatty acids on the formation of LTB4 by human neutrophils and to determine if these n-6 fatty acids themselves may be transformed into products with antiinflammatory capacity. Purified neutrophils isolated from heparinized human venous blood were incubated with A23187 (5 microM) and different concentrations (0-100 microM) of the n-6 fatty acids linoleic acid (LA) and dihomo-gamma-linolenic acid (DGLA). LO products were determined by use of quantitative reversed-phase high performance liquid chromatography (RP-HPLC) and mass spectrometry. The formation of LTB4 was dose dependently inhibited by both LA (IC50 = 45 microM) and DGLA (IC50 = 40 microM). This inhibition of LTB4 formation was associated with a dose dependent increase in the formation of the respective 15-LO products of LA (13-hydroxy-octadecadienoic acid; 13-HODE) and DGLA (15-hydroxy-eicosatrienoic acid; 15-HETrE). To determine whether these 15-LO products themselves might inhibit LTB4 formation, neutrophils were incubated with 13-HODE and 15-HETrE. Both 15-LO products lead to a dose-dependent inhibition of LTB4 formation (IC50 = 7.5 microM and IC50 = 0.2 microM). For comparison the 15-LO product of AA, 15-hydroxy-eicosatetraenoic acid (15-HETE), also inhibited LTB4 formation (IC50 = 0.75 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 8,11,14-Eicosatrienoic Acid; Anti-Inflammatory Agents, Non-Steroidal; Arachidonate 15-Lipoxygenase; Chromatography, High Pressure Liquid; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; L-Lactate Dehydrogenase; Leukotriene B4; Linoleic Acid; Linoleic Acids; Mass Spectrometry; Neutrophils

Arachidonic acid metabolism via cyclooxygenase, lipoxygenase, and cytochrome P-450 epoxygenase was investigated in thoracic aortic tissue obtained from rabbits fed either standard rabbit chow or chow containing 2% cholesterol. Aortic strips were incubated with [14C]arachidonic acid and A23187. Metabolites from extracted media were resolved by high-pressure liquid chromatography (HPLC). Normal and cholesterol-fed rabbit aortas synthesized prostaglandins (PGs) and hydroxyeicosatetraenoic acids (HETEs). The major cyclooxygenase products were 6-keto-PGF1 alpha and PGE2. Basal aortic 6-keto-PGF1 alpha production was slightly reduced in cholesterol-fed compared with normal rabbits. 12(S)- and 15(S)-HETE were the major aortic lipoxygenase products from both normal and cholesterol-fed rabbits. The structures were confirmed by gas chromatography-mass spectrometry (GC-MS). Only cholesterol-fed rabbit aortas metabolized arachidonic acid via cytochrome P-450 epoxygenase to the epoxyeicosatrienoic acids (EETs). 14,15-, 11,12-, 8,9-, and 5,6-EET were identified based on comigration on HPLC with known 14C-labeled standards and typical mass spectra. Incubation of normal aorta with 14,15-EET decreased the basal synthesis of 6-keto-PGF1 alpha. The other EETs were without effect. The four EET regioisomers relaxed the norepinephrine-precontracted normal and cholesterol-fed rabbit aorta. The relaxation response to 14,15-EET was greater in aortas from cholesterol-fed rabbits. These studies demonstrate that hypercholesterolemia, before the development of atherosclerosis, alters arachidonic acid metabolism via both the cyclooxygenase and epoxygenase pathways.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyrazol-3-amine; 6-Ketoprostaglandin F1 alpha; 8,11,14-Eicosatrienoic Acid; Animals; Aorta, Thoracic; Arachidonic Acids; Carbon Radioisotopes; Cholesterol, Dietary; Clotrimazole; Diet, Atherogenic; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Indomethacin; Kinetics; Masoprocol; Metyrapone; Muscle, Smooth, Vascular; Rabbits; Reference Values; Stereoisomerism

Noncyclooxygenase metabolites of arachidonic acid may be potent modulators of the mitogenic response of renal mesangial cells to the mitogenic vasoactive peptide arginine vasopressin (AVP). Since Ca2+ is a critical second messenger in the response of mesangial cells to AVP, and Ca2+ has been implicated in the regulation of growth, we determined whether noncyclooxygenase metabolites altered the phospholipase C-Ca2+ signalling cascade which is activated by AVP. Pretreatment of mesangial cells for 10 min with lipoxygenase and cytochrome P450 monooxygenase inhibitors, nordihydroguaiaretic acid (NDGA, 10(-5) M) or SKF-525A (2.5 x 10(-5) M), but not the cyclooxygenase inhibitor indomethacin (2 x 10(-5) M), reduced the magnitude of the AVP (10(-8) and 10(-7) M)-induced increase in cytosolic free Ca2+ concentration ([Ca2+]i) without affecting inositol trisphosphate production. With 10(-8) M AVP, [Ca2+]i increased to 250 +/- 47 nM in NDGA-treated cells versus 401 +/- 59 nM in control cells (p less than 0.01). [Ca2+]i, measured 2 min after exposure to AVP, was also lower with NDGA (152 +/- 21 nM) when compared with AVP alone (220 +/- 22 nM, p less than 0.01). 14,15-epoxyeicosatrienoic acid (EET) (10(-8) M), which had no effect on inositol trisphosphate production, completely reversed the NDGA-induced inhibition of the [Ca2+]i transient, whereas 5-hydroperoxyeicosatetraenoic acid (HPETE) (5 x 10(-7) M) did not. Pretreatment with higher concentrations of 14,15-EET (10(-7)-10(-6) M) markedly potentiated the AVP-induced increase in [Ca2+]i. NDGA-induced inhibition of the AVP-generated [Ca2+]i transient was also observed when cells were incubated in low Ca2+ media ([Ca2+] less than 5 x 10(-8) M), suggesting that NDGA pretreatment impaired intracellular release of Ca2+. Since NDGA had no direct effect on inositol 1,4,5-trisphosphate-induced Ca2+ release, we postulated that NDGA blocked production of a metabolite that releases Ca2+ from intracellular stores. 14,15-EET and 15-HPETE, but not 15-hydroxyeicosatetraenoic acid (each at 3 x 10(-7) M), raised [Ca2+]i when added directly to cells in low Ca2+ media. In permeabilized cells 14,15-EET and 15-HPETE (10(-7) M) potently released Ca2+ from intracellular stores. In summary, noncyclooxygenase metabolites of arachidonic acid, and in particular P450 metabolites, are potent endogenous amplifiers of the AVP-induced [Ca2+]i signal by mechanisms not directly involving phospholipase C activation. This effect is mediated, at least

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acid; Arachidonic Acids; Arginine Vasopressin; Calcium; Cells, Cultured; Dinoprostone; Eicosanoids; Eicosapentaenoic Acid; Glomerular Mesangium; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Indomethacin; Inositol Phosphates; Leukotrienes; Lipid Peroxides; Masoprocol; Pyridines; Rats; Rats, Inbred Strains; Signal Transduction; Type C Phospholipases

The effect of arachidonic acid and some of its metabolites have been examined in rat anterior pituitary cells for their ability to release growth hormone. The cytochrome P-450 metabolite, 5,6-epoxyeicosatrienoic acid is a much more effective growth-hormone releasing agent than 15-hydroxyeicosatetraenoic acid, 15-hydroxyeicosatetraenoic acid methyl ester, 5-hydroxyeicosatetraenoic acid or arachidonic acid. The release of growth hormone is rapid, dose-dependent and reaches an apparent saturation after eight minutes. These studies described herein provide evidence that lipoxygenase and cyclooxygenase products of arachidonic acid are less potent while cytochrome P-450 products are more potent in the release of growth hormone from anterior pituitary cells.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acids; Cells, Cultured; Fatty Acids, Unsaturated; Female; Growth Hormone; Hydroxyeicosatetraenoic Acids; Kinetics; Pituitary Gland, Anterior; Rats; Rats, Inbred F344

Mouse peritoneal macrophages metabolize dihomogammalinolenic acid (20:3n-6) primarily to 15-hydroxy-8,11,13-eicosatrienoic acid (15-OH-20:3). Since the biological properties of this novel trienoic eicosanoid remain poorly defined, the effects of increasing concentrations of 15-OH-20:3 and its arachidonic acid (20:4n-6) derived analogue. 15-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE), on mouse macrophage 20:4n-6 metabolism were investigated. Resident peritoneal macrophages were prelabeled with [3H]-20:4n-6 and subsequently stimulated with zymosan in the presence of either 15-OH-20:3 or 15-HETE (1-30 microM). After 1 hr, the radiolabeled soluble metabolites were analyzed by reverse phase high performance liquid chromatography. 15-OH-20:3 inhibited zymosan-induced leukotriene C4 (IC50 = 2.4 microM) and 5-HETE (IC50 = 3.1 microM) synthesis. In contrast to the inhibition of macrophage 5-lipoxygenase, 15-OH-20:3 enhanced 12-HETE synthesis (5-30 microM) and had no measurable effect on cyclooxygenase metabolism (1-10 microM) i.e., 6-keto-prostaglandin F1 alpha and prostaglandin E2 synthesis. Addition of exogenous 15-HETE produced similar effects. These results suggest that the manipulation of macrophage 15-OH-20:3n-6 levels may provide a measure of cellular control over 20:4n-6 metabolism, specifically, leukotriene production.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acid; Arachidonic Acids; Fatty Acids, Unsaturated; Hydroxy Acids; Hydroxyeicosatetraenoic Acids; Macrophages; Mice; SRS-A