leukotriene-e4 and 5-hydroxy-6-8-11-14-eicosatetraenoic-acid

The family of eicasanoids, biologically active metabolites of polyunsaturated C20 fatty acids such as arachidonic acid, has recently been enlarged by the recognition of a new biosynthetic pathway leading to the leukotrienes, including the compounds described two decades ago as 'slow reacting substances'. These biologically potent substances are involved in regulation of the immune response and also as mediators in various disease states. This account presents a brief history of this field, an overview of the biological relevance of leukotrienes, and a discussion of the investigations which led to the clarification of the molecular structures, pathway of biosynthesis and total chemical synthesis of the leukotrienes, including leukotrienes A, B, C, D and E (LTA-LTE). As a result of the synthetic work these rare substances are available for the first time in pure form and in quantities sufficient for biological and medical studies. Also reviewed are recent discoveries with regard to the development of inhibitors of leukotriene biosynthesis and anti-leukotrienes.

Topics: Animals; Arachidonic Acids; Asthma; Autacoids; Chemical Phenomena; Chemistry; Humans; Hydroxyeicosatetraenoic Acids; Hypersensitivity; Leukotriene A4; Leukotriene B4; Leukotriene E4; Leukotrienes; Lipoxygenase Inhibitors; Macrophages; Mast Cells; Molecular Conformation; Neutrophils; SRS-A; Stereoisomerism; Structure-Activity Relationship

The effect of tenidap on the metabolism of arachidonic acid via the 5-lipoxygenase (5-LO) pathway was investigated in vitro and in vivo.. In vitro (cells). Arachidonic acid (AA) stimulated rat basophilic leukemia, (RBL) cells; A23817 activated neutrophils (human rat, and rabbit), macrophages (rat), and blood (human). In vitro (enzyme activity). RBL-cell homogenate; purified human recombinant 5-LO. In vivo: Rat (Sprague-Dawley) models in which peritoneal leukotriene products were measured after challenge with zymosan (3 animals per group), A23187 (11 animals per group), and immune complexes (3-5 animals per group), respectively.. 5-Hydroxyeicosatetraenoic acid (5-HETE) and dihydroxyeicosatetraenoic acids (diHETEs, including LTB4) were measured as radiolabeled products (derived from [14C]-AA) or by absorbance at 235 or 280 nm, respectively, after separation by HPLC. Radiolabeled 5-HPETE was measured by a radio-TLC analyser after separation by thin layer chromatography (TLC). Deacylation of membrane bound [14C]-AA was determined by measuring radiolabel released into the extracellular medium. 5-LO translocation from cytosol to membrane was assessed by western analysis. Rat peritoneal fluid was assayed for PGE, 6-keto-PGF1 alpha, LTE4 or LTB4 content by EIA and for TXB2 by RIA.. Tenidap suppressed 5-LO mediated product production in cultured rat basophilic leukemia (RBL-1) cells from exogenously supplied AA, and in human and rat neutrophils, and rat peritoneal macrophages stimulated with A23187 (IC50, 5-15 microM). In addition, tenidap was less potent in inhibiting the release of radiolabeled AA from RBL-1 cells (IC50, 180 microM), suggesting that the decrease in 5-LO derived products could not be explained by an effect on cellular mobilization of AA (i.e., phospholipase). Tenidap blocked 5-hydroxyeicosatetraenoic acid (5-HETE) production by dissociated RBL-1 cell preparations (IC50, 7 microM), as well as by a 100000 x g supernatant of 5-LO/hydroperoxidase activity, suggesting a direct effect on the 5-LO enzyme itself. In addition, tenidap impaired 5-LO translocation from cytosol to its membrane-bound docking protein (FLAP) which occurs when human neutrophils are stimulated with calcium ionophore, indicating a second mechanism for inhibiting the 5-LO pathway. Surprisingly, tenidap did not block the binding of radiolabeled MK-0591, an indole ligand of FLAP, to neutrophil membranes. Although its ability to inhibit the cyclooxygenase pathway was readily observed in whole blood and in vivo, tenidap's 5-LO blockade could not be demonstrated by ionophore stimulated human blood, nor after oral dosing in rat models in which peritoneal leukotriene products were measured after challenge with three different stimuli. The presence of extracellular proteins greatly reduced the potency of tenidap as a 5-LO inhibitor in vitro, suggesting that protein binding is responsible for loss of activity in animal models.. Tenidap inhibits 5-lipoxygenase activity in vitro both directly and indirectly by interfering with its translocation from cytosol to the membrane compartment in neutrophils. A potential mechanism for the latter effect is discussed with reference to tenidap's ability to lower intracellular pH. Tenidap did not inhibit 5-LO pathway activity in three animal models.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Calcimycin; Chemotactic Factors; Chromatography, High Pressure Liquid; Cyclooxygenase Inhibitors; Erythrocytes; Humans; Hydroxyeicosatetraenoic Acids; Immunoenzyme Techniques; Indoles; Ionophores; Leukemia, Basophilic, Acute; Leukotriene B4; Leukotriene E4; Lipoxygenase Inhibitors; Neutrophil Activation; Neutrophils; Oxindoles; Rabbits; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Thromboxane B2; Zymosan

The aim of this work was to study the effect of high concentrations of leukotrienes on luteinizing hormone (LH) secretion in rat anterior pituitary cells. We also investigated the effect of leukotrienes in parallel with gonadotropin-releasing hormone (GnRH) action. Experiments were on cells gained from trypsinized pituitaries of female rats. Tests were performed by superfusion of the cells attached to cytodex-1 carrier beads. The LH content in samples of perfusate was estimated by radioimmunoassay. This work reports 48% inhibition of basic LH release by action of leukotriene C4 in superfused cells when applied continuously at a concentration of 100 nmol/l. Moreover, we have shown that leukotrienes suppressed GnRH-induced LH secretion in rat pituitary cells when applied in parallel to GnRH (1 nmol/l) as a 4-min pulse at a concentration of 0.1 nmol/l. GnRH-induced LH release was reduced to 66% of its value by leukotriene (LT) B4 (0.1 nmol/l) action; also to 54% by LTC4, 66% by LTD4 and 74% by LTE4 action. In contrast, arachidonic acid (50 pmol/l) and its other 5-lipoxygenase metabolites: 5-hydroperoxyeicosatetraenoic acid (5-HPETE) (50 pmol/l), or 5-hydroxyeicosatetraenoic acid (5-HETE) (50 pmol/l), had no inhibitory effect on GnRH-induced LH release. Arachidonic acid and 5-HETE potentiated GnRH-induced LH release up to 249% and 429%, respectively, when applied in parallel with GnRH (1 nmol/l) as a 4-min pulse at a concentration of 10 pmol/l. In our earlier work we have shown that several leukotrienes are potent stimulants of LH release. The present report documents the finding that the 5-lipoxygenase pathway is also involved in the inhibitory regulation of hormone release in anterior pituitary cells.

Topics: Animals; Arachidonic Acid; Cells, Cultured; Female; Gonadotropin-Releasing Hormone; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Leukotriene C4; Leukotriene D4; Leukotriene E4; Leukotrienes; Luteinizing Hormone; Perfusion; Pituitary Gland, Anterior; Rats; Rats, Sprague-Dawley; Time Factors

Alveolar macrophages (AM) may take part in the amplification of the inflammatory mechanism involved in asthma. During an asthma attack, mast cells and eosinophils release arachidonic acid derivative mediators of inflammation such as sulfidopeptide leukotrienes. Among them, LTC4 has been shown to be present in bronchoalveolar fluid. In asthmatic patients, we showed that the ability of AM to transform LTC4 into its derivatives LTD4 and LTE4 was related to the intensity of the local inflammation observed during endoscopy. AM from asthmatics incubated in the presence of LTC4 or LTE4, generated LTB4 and 5-HETE, which are potent chemoattractants. Nedocromil sodium (10(-4) M) decreased LTB4 releasability and intracellular 5-HETE concentrations in zymosan-stimulated AM from asthmatic patients, and was shown to decrease the LTC4 or LTE4-promoted formation of LTB4 and 5-HETE.

Topics: Adolescent; Adult; Aged; Anti-Inflammatory Agents, Non-Steroidal; Asthma; Bronchoalveolar Lavage Fluid; Cells, Cultured; Chromatography, High Pressure Liquid; Female; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Leukotriene E4; Leukotrienes; Macrophages, Alveolar; Male; Middle Aged; Nedocromil; Quinolones; Spectrophotometry, Ultraviolet; SRS-A; Stimulation, Chemical

The N-substituted quinolylmethoxyphenylamines, ETH603, ETH615 and ETH647, inhibited the formation of LTB4 in rat peritoneal leukocytes, human peripheral polymorphonuclear leukocytes and canine whole blood. In rat and human cells, the compounds also inhibited the formation of 5-HETE and stimulated the synthesis of 15-HETE. In rat leukocytes, the compounds were 15-30 times more potent inhibitors of LTB4 synthesis than nordihydroguaiaretic acid, but in canine whole blood they were significantly less potent, possibly due to protein binding. However, after oral administration of the compounds to dogs a long-lasting inhibition of LTB4 production in peripheral blood was observed at serum concentrations much lower than those required in vitro. Furthermore, the compounds inhibited the LTB4-directed chemotaxis and the phagocytosis of C. albicans blastospores by canine polymorphonuclear leukocytes both in vitro and following oral administration. The calcium ionophore A23187-induced release of LTB4 in the peritoneal cavity of rats was also inhibited by systemic administration of the compounds. We therefore conclude that these novel quinolines are orally active 5-lipoxygenase inhibitors which may accumulate in inflammatory cells in vivo, leading to potent inhibition of leukotriene biosynthesis and cell function.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Calcimycin; Chemotaxis, Leukocyte; Dogs; Free Radicals; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Leukotriene E4; Neutrophils; Phagocytosis; Quinolines; Rats; SRS-A

Alveolar transfer of eicosanoids was studied in the rat after instillation of [3H] prostaglandins, leukotrienes, and arachidonate into the distal airways. The percentage of originally added label remaining in lung or lavage was determined 2 min after instillation, with the remainder of the label having been transferred out of the lung. Peptidoleukotrienes were found to be largely (greater than 85%) retained in the lung after 2 min, and even after 15 min, more than 50% of the added radiolabel remained in the lung. In clear contrast, greater than 90% of the radiolabeled prostaglandin (PG) D2 was removed from the lung within 2 min after instillation. PGE2, thromboxane B2, leukotriene (LT) B4, and 5-hydroxyeicosatetraenoic acid (5-HETE) were also quickly removed from the lung, with less than 30% of the added label remaining in the lung after 2 min. Arachidonic acid and 6-keto-PGF1 alpha were removed more slowly from the lung, with 40 to 70% remaining in the lung 2 min after instillation. The arachidonic acid remaining in the lung was largely esterified into phospholipids, especially phosphatidylcholine. The 5-HETE radiolabel remaining in the lung was also associated in part with phosphatidylcholine. The radioactivity remaining in the lung after [3H] LTB4, 6-keto-PGF1 alpha, PGD2, and thromboxane B2 instillation reflected predominantly unmetabolized eicosanoids. The peptidoleukotrienes underwent a slow metabolism from LTC4 to LTD4 to LTE4. In addition, LTE4 was metabolized to a more polar product with chromatographic properties identical to those of N-acetyl LTE4. Rat lung slices and homogenates also metabolized peptidoleukotrienes via this pathway, although less N-acetyl LTE4 was produced.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Biological Transport; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Leukotriene E4; Leukotrienes; Male; Prostaglandins; Pulmonary Alveoli; Rats; Rats, Inbred Strains; SRS-A

The effect of intravenous injections of 5-, 12- and 15-hydroxyeicosatetraenoic acids (HETE), leukotrienes D4 and E4 (LTD4, LTE4) on tracheal mucous gel layer (TMGL) thickness was assessed in rats. When administered in doses ranging from 0.03 pg to 33 ng per rat, the lipoxygenase metabolites produced significant increases in TMGL thickness. The order of potency of the metabolites was 15-HETE greater than 12-HETE greater than or equal to 5-HETE greater than LTD4 greater than or equal to LTE4. Imidazole (31.6 mg/kg), intravenously, significantly decreased this response. These findings suggest that the mono-HETEs, especially 15-HETE, may be important modulators of airway mucus in the rat.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Hydroxyeicosatetraenoic Acids; Imidazoles; In Vitro Techniques; Injections, Intravenous; Leukotriene E4; Leukotrienes; Mucous Membrane; Mucus; Rats; SRS-A; Trachea

We have studied the effect of leukotrienes, (LT): B4, C4, D4 and E4 and the hydroxyeicosatetraenoic acids (HETEs) 5-HETE and 12-HETE on bone resorption in vitro. Resorption was measured by colorimetric assay of calcium released from neonatal mouse calvaria maintained in organ culture for 72h. All the LTs and HETEs stimulated bone resorption, with optimum responses at picomolar or nanomolar concentrations. The responses were biphasic, with a decreasing effect at higher concentrations. In contrast, prostaglandin E2 (PGE2) stimulated resorption only at 10nM and above. Indomethacin partially inhibited resorption by LTB4, LTC4 and LTD4, but did not affect resorption stimulated by LTE4, 5-HETE and 12-HETE. These results indicate that lipoxygenase products of arachidonic acid are highly potent bone resorbing factors and may play an important role in the localised bone loss associated with inflammatory lesions.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Arachidonic Acid; Arachidonic Acids; Bone Resorption; Hydroxyeicosatetraenoic Acids; Indomethacin; Leukotriene B4; Leukotriene E4; Leukotrienes; Lipoxygenase; Mice; SRS-A