leukotriene-c4 and Leukemia--Basophilic--Acute

Type I allergy is characterized by the release of granule-associated mediators, lipid-derived substances, cytokines, and chemokines by activated mast cells. To evaluate the anti-allergic effects of macelignan isolated from Myristica fragrans Houtt., we determined its ability to inhibit calcium (Ca(2+)) influx, degranulation, and inflammatory mediator production in RBL-2 H3 cells stimulated with A23187 and phorbol 12-myristate 13-acetate. Macelignan inhibited Ca(2+) influx and the secretion of β-hexosaminidase, histamine, prostaglandin E(2), and leukotriene C(4); decreased mRNA levels of cyclooxygenase-2, 5-lipoxygenase, interleukin-4 (IL-4), IL-13, and tumor necrosis factor-α; and attenuated phosphorylation of Akt and the mitogen-activated protein kinases extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase. These results indicate the potential of macelignan as a type I allergy treatment.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonate 5-Lipoxygenase; beta-N-Acetylhexosaminidases; Calcimycin; Calcium; Cell Degranulation; Cell Line, Tumor; Cyclooxygenase 2; Dinoprostone; Extracellular Signal-Regulated MAP Kinases; Histamine Release; Hypersensitivity; Inflammation Mediators; Interleukin-13; Interleukin-4; JNK Mitogen-Activated Protein Kinases; Leukemia, Basophilic, Acute; Leukotriene C4; Lignans; Mast Cells; Myristica; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Plant Extracts; Proto-Oncogene Proteins c-akt; Rats; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha

We previously showed that silver stimulates degranulation and leukotriene (LT) C(4) production in rat basophilic leukemia mast cells and now show that silver induces these events by a mechanism that differs from the FcepsilonRI-mediated response. In common with FcepsilonRI cross-linking, silver induced tyrosine phosphorylation of extracellular signal-regulated kinases and furthermore, PD98059, a specific inhibitor of extracellular signal-regulated kinase kinase dose-dependently inhibited the silver-induced LTC(4) production. In contrast to FcepsilonRI cross-linking, silver had no effect on the production of IL-4 and TNF-alpha, indicating that different mechanisms are involved in the activation by these two stimuli. In line with this, silver had no or only marginal effect on the tyrosine phosphorylation of FcepsilonRIbeta, Lyn, Syk, and linker for activation of T cells, the early and crucial events in FcepsilonRI signaling. Silver induced calcium signals that were involved in the metal-induced degranulation, but not LTC(4) production. Unlike Ag, the silver-induced calcium signals were resistant to the depletion of thapsigargin-sensitive calcium stores and the inhibition of tyrosine kinases and phospholipase Cgamma. These findings indicate that silver activates mast cells by bypassing the early signaling events required for the induction of calcium influx. Our data strongly suggest the existence of an alternative pathway bypassing the early signaling events in mast cell activation and indicate that silver may be useful for analyses of such alternative mechanisms.

Topics: Animals; Calcium; Calcium Signaling; Carrier Proteins; Cell Degranulation; Enzyme Precursors; Immunity, Innate; Interleukin-4; Intracellular Signaling Peptides and Proteins; Isoenzymes; Leukemia, Basophilic, Acute; Leukotriene C4; Mast Cells; Mitogen-Activated Protein Kinases; Phospholipase C gamma; Phosphoproteins; Protein-Tyrosine Kinases; Rats; Receptors, IgE; Silver; Silver Nitrate; src-Family Kinases; Syk Kinase; Thapsigargin; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha; Type C Phospholipases; Tyrosine

We have observed an inhibitory action of magnolol on the production of leukotriene (LT) C4 and LTB4, important lipid mediators in allergy and inflammation. IgE- and A23187-stimulated production of LTC4 and LTB4 was measured by radio-immunoassay (RIA) in the absence or presence of various concentrations of magnolol in intact rat basophilic leukemia (RBL)-2H3 cells. Magnolol dose-dependently inhibited synthesis of LTC4 and LTB4. Magnolol inhibited the IgE-mediated increase of intracellular calcium ion concentration, resulting in the inhibition of cytosolic phospholipase A2 (cPLA2) and possibly 5-lipoxygenase (5-LO), both calcium ion-dependent enzymes. In cell-free studies magnolol inhibited LTC4 synthase activity. LTA4 hydrolase activity was only inhibited at the higher concentration (2.5 x 10(-5)M). These results indicate that magnolol inhibits production of LTs by inhibiting PLA2, 5-LO, LTC4 synthase and LTA4 hydrolase which are essential for LT-synthesis. Magnolol may have anti-allergic effect by blocking LT-synthesis.

Topics: Animals; Biphenyl Compounds; Enzyme Inhibitors; Epoxide Hydrolases; Glutathione Transferase; Leukemia, Basophilic, Acute; Leukotriene B4; Leukotriene C4; Lignans; Lipoxygenase Inhibitors; Rats; Tumor Cells, Cultured

Myrtol standardized (Gelomyrtol/Gelomyrtol forte) inhibits the activity of 5-lipoxygenase of human basophil and eosinophil leukocytes and the formation of leukotriene C4 as well as 1.8-cineole (eucalyptol). An increase of prostaglandins (PGE2) in mucous membranes of teat cisterns after topical administration of TPA (tetradecanoylphorbol-13-acetate) was inhibited. In vitro and in vivo studies revealed spasmolytic and broncholytic effects of Myrtol stand. After topical administration into the teat cisterns of the isolated bovine udder Myrtol stand. increased the surface temperature, comparable to effects of menthol.

Topics: Animals; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Basophils; Cattle; Cyclohexanols; Dinoprostone; Drug Combinations; Drug Interactions; Eosinophils; Eucalyptol; Female; Guinea Pigs; Humans; Hyperemia; In Vitro Techniques; Inflammation; Leukemia, Basophilic, Acute; Leukotriene C4; Leukotriene D4; Leukotriene E4; Male; Mammary Glands, Animal; Menthol; Mice; Monoterpenes; Mucous Membrane; Muscle Contraction; Muscle, Smooth; Rats; Terpenes; Tetradecanoylphorbol Acetate; Trachea; Tumor Cells, Cultured

We examined the action of Shinpi-To (Formula divinita; TJ-85), a granular extract of seven Chinese medicinal herbs that is used in treating childhood asthma, on the leukotriene synthesis in rat basophilic leukemia-2H3 cells (RBL-2H3 cells). IgE-loaded cells were stimulated with anti-IgE serum in the presence or absence of Shinpi-To. Released LTC4 and LTB4 were measured by radioimmunoassay (RIA). Shinpi-To significantly inhibited IgE-mediated synthesis of leukotriene (LT)C4 and LTB4. To identify the inhibitory sites, we investigated the action of this extract on four synthetic enzymes, phospholipase A2 (PLA2), 5-lipoxygenase (5-LO). LTC4 synthase, and LTA4 hydrolase. Shinpi-To inhibited the A23187-stimulated release of [3H]arachidonic acid (AA) from the cell membrane, reflecting an effect on PLA2 activity. It also suppressed production of LTC4 and LTB4 when cell lysates were incubated with AA as substrate. It did not inhibit the production of LTC4 and LTB4 when LTA4-free acid was used as the substrate. Shinpi-To did not inhibit the IgE-mediated increase of intracellular Ca2+ ([Ca2+]i) concentration. Results indicate that Shinpi-To inhibits LT synthesis by inhibiting PLA2 and 5-LO activities without affecting the mobilization of [Ca2+]i.

Topics: Analysis of Variance; Animals; Arachidonic Acid; Asthma; Bronchodilator Agents; Calcimycin; Calcium; Cell Membrane; Drugs, Chinese Herbal; Ephedrine; Immunoglobulin E; Ionophores; Isotope Labeling; Leukemia, Basophilic, Acute; Leukotriene A4; Leukotriene B4; Leukotriene C4; Lipoxygenase Inhibitors; Phospholipases A; Phospholipases A2; Radioimmunoassay; Rats; Tritium; Tumor Cells, Cultured

Azelastine, oxatomide, and ketotifen are used for patients with allergic diseases. These drugs inhibit the release of chemical mediators including the leukotrienes; however, the mechanism involved is unclear.. To clarify the mechanism of inhibition, we investigated the effects of three drugs on the function of phospholipase A2, 5-lipoxygenase, leukotriene C4 synthase, and leukotriene A4 hydrolase, which are all catabolic enzymes involved in synthesizing leukotriene C4 and leukotriene B4 in rat basophilic leukemia (RBL)-1 cells.. The production of leukotriene C4 and leukotriene B4 was measured by high performance liquid chromatography (HPLC). All three drugs inhibited the production of leukotriene C4 and leukotriene B4 when cells were stimulated with A23187. All three drugs also inhibited the A23187-stimulated release of 3H-arachidonic acid from membrane phospholipids. Azelastine inhibited the production of leukotriene C4, but not leukotriene B4, when either arachidonic acid or leukotriene A4 free acid was used as the substrate in our cell free system. Oxatomide and ketotifen did not inhibit the synthesis of either leukotriene C4 or leukotriene B4 in the same cell free study.. Results indicated that oxatomide and ketotifen inhibit the production of leukotriene C4 and leukotriene B4 by inhibiting phospholipase A2 activity, whereas, azelastine inhibits the leukotriene C4 production by inhibiting phospholipase A2 and leukotriene C4 synthase.

Topics: Animals; Anti-Allergic Agents; Calcimycin; Epoxide Hydrolases; Glutathione Transferase; Leukemia, Basophilic, Acute; Leukotriene B4; Leukotriene C4; Lipoxygenase Inhibitors; Phospholipases A; Phospholipases A2; Phthalazines; Rats; Tumor Cells, Cultured

The effects of three Ca(2+)-ATPase inhibitors, thapsigargin (TG), cyclopiazonic acid (CPA), and 2,5-di(tert-butyl)-1,4-hydroquinone (DTBHQ), on the Ca2+ response, degranulation, and leukotriene C4 (LTC4) release in RBL-2H3 cells were investigated. All three compounds elevated the intracellular free Ca2+ concentration ([Ca2+]i), and caused degranulation in the presence of 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C activator. The dose-dependency of each compound in the Ca2+ response was in good agreement with that in degranulation. TG and CPA also caused the release of LTC4 in a dose-dependent manner, and this effect was unaffected by TPA or calphostin C, a selective PKC inhibitor. DTBHQ, however, did not induce LTC4 release, and rather inhibited the antigen-induced release of LTC4. These results suggest [1] that both degranulation and LTC4 release caused by these compounds are dependent on their [Ca2+]i increasing effect, [2] that degranulation and LTC4 release are mediated via independent pathways following the Ca2+ response, and [3] that DTBHQ additionally prevents the synthesis of LTC4 possibly by inhibition of 5-lipoxygenase.

Topics: Animals; Basophils; Calcium; Calcium-Transporting ATPases; Cell Degranulation; Dose-Response Relationship, Drug; Enzyme Inhibitors; Hydroquinones; Indoles; Leukemia, Basophilic, Acute; Leukotriene C4; Lipoxygenase Inhibitors; Mice; Naphthalenes; Spectrometry, Fluorescence; Tetradecanoylphorbol Acetate; Thapsigargin; Tumor Cells, Cultured

1'-Hydroxyeugenol- and epoxy-Z-coniferyl alcohol esters from Coreopsis species as well as synthetic derivatives of these natural compounds were examined as lipoxygenase inhibitors and as LDL (low density lipoprotein)-stabilizing agents. Most of the compounds displayed inhibitory activity on the formation of leukotrienes (LTB4 and LTC4) in a cellular (RBL-1 cells) assay as well as in a cell-free 5-lipoxygenase assay at concentrations of 4-24 mumol/l. No effect of selected compounds was observed on mammalian lipoxygenases with other specificity (12- and 15-lipoxygenase). The more lipophilic derivatives also effectively reduced Cu(2+)-mediated oxidation of LDL. The findings are discussed on the base of structure-activity relationships.

Topics: Animals; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Arachidonate 5-Lipoxygenase; Copper; Eugenol; Humans; Leukemia, Basophilic, Acute; Leukotriene B4; Leukotriene C4; Lipoproteins; Lipoxygenase Inhibitors; Oxidation-Reduction; Phenols; Rats; Structure-Activity Relationship; Tumor Cells, Cultured

We investigated inhibitory actions of dexamethasone (DEX) on retinoic acid (RA)-induced enhancement of leukotriene C4 (LTC4) synthesis in rat basophilic leukemia-1 (RBL-1) cells. Cultured cells were preincubated with RA for 16 h with or without DEX, and generation of LTC4 was measured by high performance liquid chromatography in cell-free and intact cell systems. RA (0.1 microgram/ml) significantly potentiated calcium ionophore-stimulated production of LTC4 synthesis. DEX inhibited the RA-induced enhancement of LTC4 synthesis by up to approximately 95% in intact cells when stimulated with calcium ionophore. RA-induced LTC4 synthase activity, which was determined by enzyme assay, was also inhibited by DEX by 65% in a cell-free system. This discrepancy of inhibition between the intact and cell-free systems was due to a partial inhibition of phospholipase A2 activity by DEX in the intact cells. These results indicate that the production of LTC4 is predominantly regulated at a level of LTC4 synthase. The induction of new LTC4 synthase activity by RA and inhibition of the RA-induced activity by DEX are important regulatory mechanisms of LTC4 synthesis.

Topics: Animals; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Calcimycin; Dexamethasone; Glutathione Transferase; Kinetics; Leukemia, Basophilic, Acute; Leukotriene C4; Phospholipases A; Phospholipases A2; Rats; Tretinoin; Tumor Cells, Cultured