leukotriene-e4 and acivicin

Eosinophils contain preformed stores of IL-4 within their cytoplasmic granules, but physiologic stimuli to release IL-4 from eosinophils are not yet defined.. We evaluated whether cysteinyl leukotrienes (CysLTs) could elicit IL-4 release from eosinophils.. We used a dual-antibody capture and detection assay (EliCell) for IL-4 release and used eosinophils differentiated in vitro from human cord blood-derived progenitors.. Leukotriene (LT) C4, LTD4, and LTE4 each elicited the rapid, vesicular transport-mediated, dose- and time-dependent release of IL-4 from eosinophils. Both LTD4 and LTE4 evoked similar and earlier IL-4 release than LTC4. LTC4 did not act directly but only after conversion to LTD4 because an inhibitor of gamma-glutamyl transpeptidase, acivicin, blocked LTC4-induced IL-4 release. MK571 and LY171833, receptor antagonists for CysLT1 and not CysLT2, and pertussis toxin inhibited LTC4-, LTD4-, and LTE4-induced IL-4 release. Cord blood-differentiated eosinophils contained CysLT1 protein detectable by means of immunoblotting.. CysLTs acting through G(i) protein-coupled and MK571- and LY171833-inhibitable receptors on cord blood-derived human eosinophils can act as autocrine or paracrine mediators to stimulate the rapid, nonexocytotic release of preformed IL-4.

Topics: Acetophenones; Animals; Cysteine; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Eosinophils; Fetal Blood; Humans; Immunohistochemistry; Inflammation Mediators; Interleukin-4; Isoxazoles; Leukotriene C4; Leukotriene D4; Leukotriene E4; Leukotrienes; Membrane Proteins; Microscopy, Fluorescence; Pertussis Toxin; Propionates; Quinolines; Rabbits; Receptors, Leukotriene; Tetrazoles; Time Factors; Virulence Factors, Bordetella

1. The uptake, metabolism and biliary excretion of the cysteinyl leukotrienes LTC4, LTD4 and LTE4, were studied in a non-recirculating rat liver perfusion system at constant flow in both antegrade (from the portal to the caval vein) and retrograde (from the caval to the portal vein) perfusion directions. During a 5-min infusion of [3H]LTC4, [3H]LTD4 and [3H]LTE4 (10 nmol/l each) in antegrade perfusions single-pass extractions of radioactivity from the perfusate were 66%, 81% and 83%, respectively. Corresponding values for LTC4 and LTD4 in retrograde perfusions were 83% and 93%, respectively, indicating a more efficient uptake of cysteinyl leukotrienes in retrograde than in antegrade perfusions. The concentrations of unmetabolized leukotrienes in the effluent perfusate were 8-12% in antegrade and 2-4% in retrograde perfusions. [14C]Taurocholate extraction from the perfusate was inhibited by LTC4 by only 3%, suggesting that an opening of portal-venous/hepatic-venous shunts does not explain the effects of perfusion direction on hepatic LTC4 uptake. 2. Following infusion of [3H]LTC4 and [3H]LTD4, in the antegrade perfusion direction, about 80% and 87%, respectively, of the radiolabel taken up by the liver was excreted into bile. In retrograde perfusions, however, only 40% and 57%, respectively, was excreted into bile and the remainder was slowly redistributed into the perfusate, indicating that leukotrienes were taken up into a hepatic compartment with less effective biliary elimination or converted to metabolites escaping biliary excretion. The metabolite pattern found in bile was not affected by the direction of perfusion. Biliary products of LTC4 were polar metabolites (31-38%), LTD4 (27-30%), LTE4 (about 1%) and N-acetyl-LTE4 (3-4%) in addition to unmodified LTC4 (17-18%). 3. LTC4 was identified as a major metabolite of [3H]LTD4 in bile, amounting to about 20% of the total radioactivity excreted into bile. This is probably due to a gamma-glutamyltransferase-catalyzed glutamyl transfer from glutathione in the biliary compartment, as demonstrated in in vitro experiments. The presence of sinusoidal gamma-glutamyltransferase activity in perfused rat liver was shown in experiments on the hydrolysis of infused gamma-glutamyl-p-nitroanilide. 90% inhibition of this enzyme activity by AT-125 did not affect the metabolism of LTC4. 4. When [3H]LTE4 was infused in the antegrade perfusion direction, biliary metabolites comprised N-acetyl-LTE4 (24%) and polar component

Topics: Aniline Compounds; Animals; Antimetabolites; Bile; Biological Transport; Chromatography, High Pressure Liquid; gamma-Glutamyltransferase; Isoxazoles; Leukotriene E4; Liver; Male; Perfusion; Rats; Rats, Inbred Strains; SRS-A; Taurocholic Acid

The pathogenic mechanism of fulminant hepatitis induced by 700 mg/kg D-galactosamine plus 33 micrograms/kg endotoxin was investigated in male NMRI mice. The extent of liver injury was assessed by measurement of serum transaminases and sorbitol dehydrogenase activities 9 hr after intoxication, as well as by histopathological evaluation. When the hepatic glutathione content of galactosamine endotoxin-treated animals had been decreased by more than 90% following administration of 250 mg/kg phorone or 400 mg/kg diethyl maleate given three times, no signs of liver injury were observed. Since different agents interfering with the leukotriene synthesis pathway also prevented galactosamine/endotoxin-induced hepatitis, we suspected that a glutathione-derived peptidoleukotriene may be the pathogenic metabolite. In vivo inhibition of the catabolism of leukotriene C4 by administration of 50 mg/kg of the glutamyl transpeptidase inhibitor AT 125 (Acivicin) also protected the animals against liver injury. In order to elucidate which metabolite of leukotriene C4 was responsible for the observed hepatotoxicity we intravenously injected leukotrienes into animals that had received only galactosamine. Injection of 50 micrograms/kg leukotriene E4 1 hr after galactosamine had no effect. The same dose of leukotriene D4 led to a fulminant hepatitis which was prevented when the leukotriene D4 antagonist FPL 55712 had been given before. In contrast, lipoxygenase inhibitors or AT 125 did not protect against galactosamine + LTD4. Galactosamine/endotoxin-induced and galactosamine/leukotriene D4-induced hepatitis resulted in similarly localized histopathological changes, i.e. diffuse necrosis in the organ. We conclude from our results that galactosamine/endotoxin-induced hepatitis is mediated by a leukotriene D4-dependent mechanism.

Topics: Animals; Chemical and Drug Induced Liver Injury; Endotoxins; Galactosamine; Glutathione; Isoxazoles; Leukotriene E4; Liver; Male; Mice; SRS-A

Rat basophilic leukemia (RBL-1) cells incubated with ionophore A23187 and 5,8,11-eicosatrienoic acid produced three slow-reacting substances identified as leukotrienes C3, D3 and E3 by spectroscopic, chromatographic and enzymatic methods. 5,8,11,14,17-Eicosapentaenoic acid was similarly converted by RBL-1 cells to leukotrienes C5, D5. and E5. Leukotrienes C4, D4 and E4 were also formed in these experiments from endogenous arachidonic acid. Time-course studies, incubations with 3H-labeled leukotriene C3 and effects of acivicin [L-(alpha S, 5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid; a gamma-glutamyl transpeptidase inhibitor] indicated that leukotrienes C and D are intermediates in the formation of leukotrienes E. L-Cysteine enhanced the conversion of leukotriene C3 to leukotriene D3 and inhibited further degradation of leukotriene D3 to leukotriene E3.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acid; Arachidonic Acids; Basophils; Calcimycin; Chromatography, High Pressure Liquid; Cysteine; Glycine; Isoxazoles; Leukemia, Experimental; Leukotriene E4; Rats; SRS-A