Antigen-induced Histamine Release Research Articles

Exocytic machineries differentially control mediator release from allergen-triggered RBL-2H3 cells.

Mast cells utilize SNAREs (soluble-N-ethyl-maleimide sensitive factor attachment protein receptors) and SM (Sec1/Munc18) proteins to secrete/exocytose a variety of proinflammatory mediators. However, whether a common SNARE-SM machinery is responsible remains unclear. Four vesicle/granule-anchored SNAREs (VAMP2, VAMP3, VAMP7, and VAMP8) and two Munc18 homologs (Munc18a and Munc18b) were systematically knocked down or knocked out in RBL-2H3 mast cells and antigen-induced release of β-hexosaminidase, histamine, serotonin, and TNF was examined. Phenotypes were validated by rescue experiments. Immunofluorescence studies were performed to determine the subcellular distribution of key players. The reduction of VAMP8 expression inhibited the exocytosis of β-hexosaminidase, histamine, and serotonin but not TNF. Unexpectedly, however, confocal microscopy revealed substantial co-localization between VAMP8 and TNF, and between TNF and serotonin. Meanwhile, the depletion of other VAMPs, including knockout of VAMP3, had no impact on the release of any of the mediators examined. On the other hand, TNF exocytosis was diminished specifically in stable Munc18bknockdown cells, in a fashion that was rescued by exogenous, RNAi-resistant Munc18b. In line with this, TNF was co-localized with Munc18b (47%) to a much greater extent than with Munc18a (13%). Distinct exocytic pathways exist in mast cells for the release of different mediators.

Evaluation of Antiasthamic Activity of Electrohomeopathy Formulation Pettorale on Experimental Animals

Objective: The current study was planned to evaluate the antiasthamatic effect of Electrohomeopathic medicine Pettorale in various experimental models.
 Methods: The antiasthmatic activity of Electrohomeopathic medicine Pettorale was studied on different experimental animals like histamine induced bronchospasm in guinea pig, haloperidol induced catalepsy in rats, egg albumin induced paw anaphylaxis in rats and milk induced leukocytosis in mice.
 Conclusion: Preliminary phytochemical screening has revealed the presence of alkaloids, glycosides, carbohydrates, amino acids, proteins, steroids and terpenoids. Petorella exhibited best antihistaminic activity at the dose of 400 mg/kg. It inhibited haloperidol-induced catalepsy, increased leukocyte count and increased eosinophil count due to milk allergen. Antiasthmatic activity of Pettorale may be possible due to the membrane stabilising potential, suppression of antibody production and inhibition of antigen induced histamine release.
 Keywords: Electrohomeopathy, Pettorale, catalepsy, asthma, histamine

Forty Years Since the Structural Elucidation of Platelet-Activating Factor (PAF): Historical, Current, and Future Research Perspectives.

In the late 1960s, Barbaro and Zvaifler described a substance that caused antigen induced histamine release from rabbit platelets producing antibodies in passive cutaneous anaphylaxis. Henson described a ‘soluble factor’ released from leukocytes that induced vasoactive amine release in platelets. Later observations by Siraganuan and Osler observed the existence of a diluted substance that had the capacity to cause platelet activation. In 1972, the term platelet-activating factor (PAF) was coined by Benveniste, Henson, and Cochrane. The structure of PAF was later elucidated by Demopoulos, Pinckard, and Hanahan in 1979. These studies introduced the research world to PAF, which is now recognised as a potent phospholipid mediator. Since its introduction to the literature, research on PAF has grown due to interest in its vital cell signalling functions and more sinisterly its role as a pro-inflammatory molecule in several chronic diseases including cardiovascular disease and cancer. As it is forty years since the structural elucidation of PAF, the aim of this review is to provide a historical account of the discovery of PAF and to provide a general overview of current and future perspectives on PAF research in physiology and pathophysiology.

Ergosterol and its derivatives from Grifola frondosa inhibit antigen-induced degranulation of RBL-2H3 cells by suppressing the aggregation of high affinity IgE receptors.

Grifola frondosa is an edible mushroom consumed as a health food and/or traditional medicine in Asia. However, the anti-allergic effects of G. frondosa are not yet understood. In this study, we demonstrated the effects of G. frondosa extract (GFE) on IgE-mediated allergic responses, using antigen-stimulated RBL-2H3 cells. Three active compounds: ergosterol, 6β-methoxyergosta-7,22-dien-3β,5α-diol (MEDD), and 6-oxoergosta-7,22-dien-3β-ol (6-OXO) were isolated from GFE and shown to inhibit the antigen-induced release of β-hexosaminidase and histamine. Among the three active components, we focused on ergosterol because of its high content in GFE. Ergosterol inhibited the aggregation of high-affinity IgE receptor (FcεRI), which is the first step in the activation of mast cells and antigen-induced tyrosine phosphorylation. Furthermore, ergosterol suppressed antigen-increased IL-4 and TNF-α mRNA. Taken together, our findings suggest that G. frondosa, including ergosterol and its derivatives as active components, has the potential to be a novel functional food that prevents type I allergies.

DIETARY EFFECTS OF MAGNESIUM ON HISTAMINE METABOLISM AND URINE ACIDITY IN DOMESTIC FELINES

Magnesium deficiency has been associated with increased histamine production in rats. Limitation of Mg with acidifying foods is common practice for management of urinary tract health in domestic cats. Nine healthy adult female shorthair cats were used in a 3 period random crossover experiment with fixed treatment sequences to test the effects of dietary Mg (0.06, 0.12 and 0.18% DM) on histamine in blood and urine. The dry-extruded test foods were fed in sufficient amounts to maintain ideal body weight and obtain a target urine pH of 6.3. Each experimental period was preceded by a 7d wash out period, in which the 0.06% Mg food was fed, followed by a 14d feeding period of the appropriate food. Two 24 h total urine collections were performed (d13: Acidified, d14: Un-acidified; immediately iced) and blood was collected on d14. Dry matter intake (p≥0.13) and BW (p≥0.13) were not affected by treatment. Plasma Mg concentration increased linearly with increasing dietary Mg (0.54, 0.56, 0.58 mM; p = 0.001). In contrast, plasma concentrations of threonine, histidine and tryptophan were lower in cats fed 0.12% Mg compare with 0.06 or 0.18% Mg (quadratic, p≤0.03). Urine output (p≥0.17), pH (p≥0.55), NH3 (p≥0.21) and titratable acidity of urine (p≥0.14) were similar across treatments. Urinary histamine excretion responded quadratically (p = 0.02) to treatment (3483, 3369, 3986 ng/d), whereas urinary histamine: Creatinine (p≥0.43) and plasma histamine concentration (p≥0.55) were unaffected. Differences were not detected among treatments in total histamine, cellular + noncellular histamine, (p≥0.11) or antigen-induced (p≥0.21) histamine release in whole blood. These data indicate that dietary Mg concentration, from 0.06-0.18%, does not affect urinary acidity or circulating histamine concentrations, however, supplying Mg at 0.18% may increase urinary histamine excretion.

Inhibition of allergic airway responses by heparin derived oligosaccharides: identification of a tetrasaccharide sequence

BackgroundPrevious studies showed that heparin's anti-allergic activity is molecular weight dependent and resides in oligosaccharide fractions of <2500 daltons.ObjectiveTo investigate the structural sequence of heparin's anti-allergic domain, we used nitrous acid depolymerization of porcine heparin to prepare an oligosaccharide, and then fractionated it into disaccharide, tetrasaccharide, hexasaccharide, and octasaccharide fractions. The anti-allergic activity of each oligosaccharide fraction was tested in allergic sheep.MethodsAllergic sheep without (acute responder) and with late airway responses (LAR; dual responder) were challenged with Ascaris suum antigen with and without inhaled oligosaccharide pretreatment and the effects on specific lung resistance and airway hyperresponsiveness (AHR) to carbachol determined. Additional inflammatory cell recruitment studies were performed in immunized ovalbumin-challenged BALB/C mice with and without treatment.ResultsThe inhaled tetrasaccharide fraction was the minimal effective chain length to show anti-allergic activity. This fraction showed activity in both groups of sheep; it was also effective in inhibiting LAR and AHR, when administered after the antigen challenge. Tetrasaccharide failed to modify the bronchoconstrictor responses to airway smooth muscle agonists (histamine, carbachol and LTD4), and had no effect on antigen-induced histamine release in bronchoalveolar lavage fluid in sheep. In mice, inhaled tetrasaccharide also attenuated the ovalbumin-induced peribronchial inflammatory response and eosinophil influx in the bronchoalveolar lavage fluid. Chemical analysis identified the active structure to be a pentasulfated tetrasaccharide ([IdoU2S (1→4)GlcNS6S (1→4) IdoU2S (1→4) AMan-6S]) which lacked anti-coagulant activity.ConclusionsThese results demonstrate that heparin tetrasaccharide possesses potent anti-allergic and anti-inflammatory properties, and that the domains responsible for anti-allergic and anti-coagulant activity are distinctly different.

Enhancing effects of trichloroethylene and tetrachloroethylene on type I allergic responses in mice

Trichloroethylene (TCE) and tetrachloroethylene (perchloroethylene; PCE) are commonly identified as environmental contaminants of groundwater. Previously, we investigated the enhancing effects of TCE and PCE on antigen-induced histamine release and inflammatory mediator production in rat mast cells. In this study, to examine the potential effect of TCE and PCE on antigen-induced histamine release from mouse mast cells, mouse bone marrow-derived mast cells (BMMC) were sensitized with anti-dinitrophenol (DNP) monoclonal IgE antibody and then stimulated with DNP-BSA containing with TCE or PCE. Both TCE and PCE significantly enhanced antigen-induced histamine release from BMMC. Next we investigated the effects of TCE and PCE on the passive cutaneous anaphylaxis (PCA) reaction in vivo using ICR mice. TCE and PCE significantly enhanced the PCA reaction in a dose-dependent manner. In addition, we examined the enhancing effects of ingesting small amount of TCE and PCE in drinking water on antigen-stimulated allergic responses. After the ICR mice had ingested TCE or PCE in their drinking water for 2 or 4 weeks, we performed the PCA reaction. Both TCE and PCE ingestion enhanced the PCA reaction in a dose-dependent manner for 4 weeks. These results suggest that exposure to TCE and PCE leads to the augmentation of type I allergic responses in many species.

The suppression of IgE-mediated histamine release from mast cells following exocytic exclusion of biodegradable polymeric nanoparticles

The objective of this study is to evaluate the effect of polymeric nanoparticles (NPs) on the allergic response of mast cells that release inflammatory mediators such as histamine through exocytosis. Submicron-sized biodegradable poly( dl-lactide-co-glycolide) (PLGA) NPs were prepared by the emulsion solvent diffusion method. Here, we examined the interactions of the mast cells with two types of PLGA NPs, unmodified NPs and NPs modified with chitosan (CS), a biodegradable cationic polymer. The cellular uptake of NPs increased by CS modification due to electrostatic interactions with the plasma membrane. NPs were taken up by mast cells through an endocytic pathway (endocytic phase) and then the cellular uptake was saturated and maintained plateau level by the exclusion of NPs through exocytosis (exocytic phase). Antigen-induced histamine release from mast cells was inhibited during the exocytic phase. The extent of histamine release inhibition was related to the amount of excluded NPs. Exocytic exclusion of NPs competitively antagonize the antigen-induced exocytotic release of histamine by highjacking exocytosis machinery such as SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins, since histamine release was recovered in mast cells that overexpress SNAP-23. The inhibitory effect of the allergic response by PLGA NPs was also evaluated in vivo using the mouse model for systemic anaphylaxis. The administration of NPs suppressed the antigen-induced systemic allergic response in vivo. In conclusion, PLGA NP itself has actions to inhibit the allergic responses mediated by mast cells.

Structural requirements for the inhibition of calcium mobilization and mast cell activation by the pyrazole derivative BTP2

Mast cells play a critical role in the development of the allergic response. Upon activation by allergens and IgE via the high affinity receptor for IgE (FcɛRI), these cells release histamine and other functional mediators that initiate and propagate immediate hypersensitivity reactions. Mast cells also secrete cytokines that can regulate immune activity. These processes are controlled, in whole or part, by increases in intracellular Ca 2+ induced by the FcɛRI. We show here that N-(4-(3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl)phenyl)-4-methyl-1,2,3-thiadiazole-5-carboxamide (BTP2), a pyrazole derivative, inhibits activation-induced Ca 2+ influx in the rat basophil cell line RBL-2H3 and in bone marrow-derived mast cells (BMMCs), without affecting global tyrosine phosphorylation of cellular proteins or phosphorylation of the mitogen-activated protein kinases Erk1/2, JNK and p38. BTP2 also inhibits activation-induced degranulation and secretion of interleukin (IL)-2, IL-3, IL-4, IL-6, IL-13, tumor necrosis factor (TNF)-α, and granulocyte macrophage-colony stimulating factor (GM-CSF) by BMMCs, which correlates with the inhibition of Nuclear Factor of Activated T cells (NFAT) translocation. In vivo, BTP2 inhibits antigen-induced histamine release. Structure–activity relationship analysis indicates that substitution at the C3 or C5 position of the pyrazole moiety on BTP2 (5-trifluoromethyl-3-methyl-pyrazole or 3-trifluoromethyl-5-methyl-pyrazole, respectively) affected its activity, with the trifluoromethyl group at the C3 position being critical to its activity. We conclude that BTP2 and related compounds may be potent modulators of mast cell responses and potentially useful for the treatment of symptoms of allergic inflammation.

Effects of a 5-lipoxygenase inhibitor, REV-5901, on leukotriene and histamine release from human lung tissue in-vitro

REV-5901, alpha-pentyl-3-(2-quinolinylmethoxy)benzenemethanol, is an arylmethylphenyl ether derivative which inhibits 5-lipoxygenase activity of leukocytes. Its effects on the release of leukotrienes, induced by antigen and calcium ionophore, from human lung tissue in-vitro have been examined. At 1 and 10 microM it significantly inhibited the release of leukotrienes induced by both stimuli. At 10 microM it also inhibited antigen-induced histamine release. These results suggest that REV-5901 may be useful in clinical disorders such as asthma in which leukotriene release may be involved.

Structural requirements for the inhibition of calcium mobilization and mast cell activation by the pyrazole derivative BTP2 (107.16)

Abstract Cytosolic Ca2+ changes in mast cells are central for driving their activation. Thus, pharmacological tools that inhibit this process represent unique strategies for inhibiting mast cell function and their contribution to disease. We find that the pyrazole compound BTP2 inhibited FcϵRI-triggered sustained Ca2+ influx in RBL-2H3 cells and murine BMMCs with little effect on the tyrosine phosphorylation of cellular proteins. It also did not affect FcϵRI-induced phosphorylation of mitogen-activated protein kinases Erk1/2, JNK, and p38 nor downstream c-fos expression. This suggests that BTP2 inhibits Ca2+ mobilization without affecting the FcϵRI signal transduction cascade. In vitro, BTP2 inhibited FcϵRI-triggered degranulation and cytokine secretion, correlating with inhibition of NFAT nuclear translocation. Consistent with this effect, BTP2 inhibited antigen-induced histamine release in vivo. Analysis of structure-function relationships between the BTP2 parent compound and its derivatives implicate a role for the trifluoromethyl group at both carbon positions 3 and 5 of pyrazole in the inhibition of degranulation of BMMCs, with a more dominant effect evoked by the trifluoromethyl group at C3. In conclusion, our studies indicate that pyrazole compounds can provide the molecular framework for the design of specific inhibitors of Ca2+ entry mechanisms and further BTP2 as a medicinal candidate for the treatment of allergic reactions and other mast cell-mediated diseases.

Matsutake Mushroom-induced Anaphylactic Reaction: The Patient's Nonreleasing Basophils Showed Antigen-induced Histamine Release After 3-day Treatment With IL-3

RATIONALE: A small number of reports suggest that Matsutake mushroom can induce anaphylaxis on rare occasions. Skin tests using mushrooms are reported to be useful in these cases. Here we report a woman with bronchial asthma, who told us two episodes of Matsutake-induced anaphylaxis that had occurred approximately ten years before. She said that other mushrooms had never induced allergic reactions.

Potent inhibition of calcium mobilization and mast cell activation by the pyrazole derivative BTP2 (86.9)

Abstract Cytosolic Ca2+ changes in mast cells are central for driving their activation. Thus, pharmacological tools that inhibit this process represent unique strategies for inhibiting mast cell function. We find that the pyrazole compound BTP2 inhibited FcϵRI-triggered sustained Ca2+ influx in a mast cell-like cell line RBL-2H3 with little effect on the tyrosine phosphorylation of cellular proteins. It also did not affect FcϵRI-induced phosphorylation of mitogen-activated protein kinases Erk1/2, JNK, and p38 nor downstream c-fos expression. This suggests that BTP2 inhibits Ca2+ mobilization without affecting the FcϵRI signal transduction cascade. BTP2 inhibited degranulation and β-hexosaminidase release in RBL-2H3 cells. Consistent with this effect, BTP2 inhibited antigen-induced histamine release in vivo. BTP2 also inhibited cytokine secretion of IL-2, IL-3, IL-4, IL-13, and TNF-α by BMMCs. Analysis of structure-function relationships between the BTP2 parent compound and its derivatives implicate a role for the trifluoromethyl group at both carbon positions 3 and 5 of pyrazole in the inhibition of degranulation of RBL-2H3 cells, with a more dominant effect evoked by the trifluoromethyl group at C3. In conclusion, our studies indicate that pyrazole compounds can provide the molecular framework for the design of specific inhibitors of Ca2+ entry mechanisms and further BTP2 as a medicinal candidate for the treatment of allergic reactions and other mast cell-mediated diseases.

FcepsilonRI-alpha siRNA inhibits the antigen-induced activation of mast cells.

FcepsilonRI, The high affinity receptor for IgE plays a critical role in triggering the allergic reactions. It is responsible for inducing mast cell degranulation and deliberation of allergy mediators when it is aggregated by allergen and IgE complexes. FcepsilonRI on the mast cells consists of three subunits; alpha chain directly binds IgE, beta chain and dimmer of gamma chains together mediate intracellular signaling. Cross-linking of IgE-bound FcepsilonRI on the surface of mast cells and basophils by the multivalent antigen induces release of chemical mediators. The present in vitro study was designed to investigate the effect of synthetic FcepsilonRI-alpha siRNA on the antigen-induced activation of MC/9 cells. MC/9 cells which are murine mast cells were transfected by FcepsilonRI-alpha siRNA and negative control siRNA. After 6 h, anti-DNP (Dinitrophenyl) IgE was used for the cells sensitization. Then the cells were challenged with Dinitrophenyl-Human Serum Albumin (DNP-HSA) for mast cell degranulation induction before collection of supernatants. The amount of mRNA and protein expression was measured by Real Time PCR and western blot analysis, respectively. Determination of the expression rate of FcepsilonRI-alpha on cell surface was achieved by flow cytometry. ELISA and spectrophotometry methods were used subsequently for measuring the effects of FcepsilonRI-alpha siRNA on antigen-induced histamine and beta-hexosaminidase release. FcepsilonRI-alpha siRNA treated cells showed significant decrease in FcepsilonRI-alpha mRNA and protein expression in comparison to control cells. FcepsilonRI-mediated mast cell release of beta-hexosaminidase and histamine were also inhibited. In this study it was shown that FcepsilonRI-alpha siRNA could suppress FcepsilonRI-alpha expression and inhibited degranulation and histamine release in antigen-stimulated MC/9 cells. In conclusion, knock-down of FcepsilonRI-alpha by siRNA could be a promising method for inhibition of the mast cell-mediated allergic reactions.

Antianaphylactic activity of alcoholic extract ofEclipta alba

The antianaphylactic activity of alcoholic extract of Eclipta alba with two different doses of 250 and 500 mg/kg was studied by using different animal models such as effect on mast cell degranulation using rat mesentery, passive cutaneous anaphylaxis using rat, by measuring leakage of Evans blue dye in skin, passive paw anaphylaxis using rat by measuring the paw volume by plethysmometer. Bronchoalveolar lavage (BaL) s uid study in guinea pig trachea, measurement of different blood cells, and level of histamine in lung tissues was performed. Treatment with alcoholic extract of Eclipta alba showed a dose dependent beneÞ cial effect on degranulation of mast cells in rats when challenged with Compound 48/80. Further, a dose-dependent beneÞ cial effect was also observed on leakage of Evans blue dye in skin challenged with antigen. Eclipta alba showed beneÞ cial effect on paw anaphylaxis induced by antiserum and also on inÞ ltration of various ins ammatory cells as well as on histamine release from lungs. Antianaphylactic activity of alcoholic extract of Eclipta alba may be possibly due to its membrane stabilizing potential, inhibition of antigen induced histamine release, and inhibition of release of various ins ammatory mediators. Key words: Allergy, compound 48/80, ovalbumin.

Inhibition of the Antigen-Induced Activation of RBL-2H3 Cells by Gab2 siRNA

Gab2 plays an important role in FcepsilonRI mediated signal events which lead to degranulation from mast cells. The present study was designed to investigate the effect of the synthetic Gab2 (scaffolding adapter Grb2-associated binder 2) siRNA on the antigen-induced activation of RBL-2H3 cells. A double stranded siRNA against Gab2-mRNA was synthesized and transfected into RBL-2H3 cells. After 6 h, cells were then sensitized with dinitrophenyl (DNP)-specific IgE overnight and challenged with dinitrophenyl-human serum albumin (DNP-HSA) to induce mast cell degranulation before supernatants were collected. Effects of Gab2 siRNA on antigen-induced release of beta-hexosaminidase and histamine, cytokine production and regulation of the proteins in the pathway were measured by enzymatic assay, EIA, ELISA and Western blotting. Treatment with Gab2 siRNA significantly decreased Gab2 expression, inhibited the FcepsilonRI-mediated mast cell release of beta-hexosaminidase and histamine, reduced the production of IL-4 and TNF-alpha and inhibited the phosphorylation of Akt, PKCdelta and p38 mitogen-activated protein kinase (MAPK). Data showed that Gab2 siRNA could suppress the antigen-induced activation of RBL-2H3 cells and suggested a possible mechanism through inhibition of signaling molecules downstream of Gab2 in the FcepsilonRI-mediated Ca(2+)-independent pathway. Furthermore, potential usefulness of Gab2 knock-down as a method for inhibition of mast cell-mediated allergic reactions was demonstrated.

Effects of a selection of histone deacetylase inhibitors on mast cell activation and airway and colonic smooth muscle contraction

Studies of histone deacetylase (HDAC) inhibitors, novel anticancer drugs, in models of autoimmune diseases, asthma, and inflammatory bowel disease suggest that HDAC inhibitors may also have useful anti-inflammatory effects. Accordingly, in vitro studies relevant to asthma and inflammatory bowel disease were conducted using a selection of HDAC inhibitors: suberoylanilide hydroxamic acid (SAHA, Vorinostat™), and a related branched hydroxamic acid, diamide (1), MGCD0103 and two short chain fatty acid derivatives: sodium butyrate (of use in inflammatory bowel disease) and sodium valproate. The ability of those HDAC inhibitors to modulate antigen- or agonist-induced contraction of isolated guinea pig tracheal rings and colon, agonist-induced contraction of rat colon, and histamine release from rat peritoneal mast cells was examined. Pre-incubation (up to 6 h) with 10–40 µM of SAHA, diamide (1), or MGCD0103 caused significant inhibition of the antigen-induced contraction of sensitised guinea pig tracheal rings as well as inhibition of the contraction induced by histamine, 5-hydroxytryptamine and carbachol (G-protein coupled receptor agonists), while sodium butyrate (1 mM) and sodium valproate (100 µM) were weak inhibitors. Contraction of tracheal rings by sodium fluoride (NaF, a non-selective G-protein activator), KCl and a peroxyl radical generator was blocked by MGCD0103. Additionally, MGCD0103 significantly inhibited antigen-induced histamine release from IgE antibody-sensitised rat peritoneal mast cells, and NaF-induced histamine release, as well as inhibiting NaF-induced colon contraction. Those various effects appear to involve modulation of cell signaling, probably involving G-protein coupled pathways, and further support the development of HDAC inhibitors as anti-inflammatory agents.

Antigen-Induced Histamine Release From Purified Basophils As a Novel In Vitro Test For Egg Allergy

Antigen-Induced Histamine Release From Purified Basophils As a Novel In Vitro Test For Egg Allergy

The suppressive effects of YM-58483/BTP-2, a store-operated Ca 2+ entry blocker, on inflammatory mediator release in vitro and airway responses in vivo

YM-58483/BTP-2, 4-methyl-4′-[3,5- bis(trifluoromethyl)-1H-pyrazol-1- yl]-1,2,3-thiadiazole-5-carboxanilide, blocks the store-operated Ca 2+ entry (SOCE) that mediates the activation of non-excitable cells. This study investigated the pharmacological profile and therapeutic potential of YM-58483 as anti-asthma drug. YM-58483 inhibited DNP antigen-induced histamine release from and leukotrienes (LTs) production in IgE-primed RBL-2H3 cells, a rat basophilic leukemia cell line, with IC 50 values of 460 and 310 nM, respectively. Prednisolone did not inhibit either of these responses. YM-58483 also inhibited phytohemagglutinin-P (PHA)-stimulated IL-5 and IL-13 production in human peripheral blood cells with IC 50 values of 125 and 148 nM, respectively, which is approximately 5 times less potent than prednisolone. YM-58483 (30 mg/kg, p.o.) significantly suppressed ovalbumin (OVA)-induced bronchoconstriction in OVA-sensitized guinea pigs, whereas prednisolone did not. YM-58483 (3–30 mg/kg, p.o.) and prednisolone (100 mg/kg, p.o.) both significantly and completely suppressed airway hyperresponsiveness (AHR) caused by OVA exposure. Since YM-58483 inhibits two major characteristic symptoms of bronchial asthma, namely bronchoconstriction and AHR via the suppression of inflammatory mediator and cytokine production, SOCE inhibition is a potential approach for treatment.

Enhancing effect of chlorinated organic solvents on histamine release and inflammatory mediator production

We investigated the effect of several chlorinated organic solvents on antigen-induced histamine release and inflammatory mediator production. Non-purified rat peritoneal mast cells (NPMC) and rat basophilic leukemia (RBL-2H3) cells were sensitized with anti-dinitrophenol (DNP) monoclonal IgE antibody, and then stimulated with DNP-conjugated bovine serum albumin (DNP-BSA) and several chlorinated organic solvents. Trichloroethylene (TCE) and tetrachloroethylene (PCE) enhanced histamine release from antigen-stimulated NPMC and RBL-2H3 in a dose-dependent manner. In addition, TCE and PCE increased IL-4 and TNF-α production from antigen-stimulated RBL-2H3. In an in vivo study, we investigated the effect of TCE and PCE on passive cutaneous anaphylaxis (PCA) reaction. TCE and PCE enhanced PCA reaction markedly. These results suggest that TCE and PCE increase histamine release and inflammatory mediator production from antigen-stimulated mast cells via the modulation of immune responses. In addition, exposure to TCE and PCE may lead to the augmentation of allergic diseases.