prostaglandin-d2 and Bronchial-Hyperreactivity

Allergic inflammation is orchestrated by mainly antigen-specific CD4+ T cells, eosinophils and mast cells, which is a characteristic feature of bronchial asthma, rhinitis and atopic dermatitis. Prostanoids are one of the arachidonic metabolites, which are produced by a variety of inflammatory cells upon stimulation and are thought to be involved in the pathogenesis of diseases as well as the regulation of homeostasis. We investigated the role of a prostanoid, prostaglandin D2 (PGD2), in the pathogenesis of allergic bronchial asthma using its receptor, DP, gene-deficient mice. We found that the disruption of the DP gene attenuated the allergen-induced airway eosinophilic inflammation, Th2 type cytokine production and bronchial hyperresponsiveness to cholinergic stimuli, suggesting that PGD2 is an important mediator of allergic asthma. In contrast, the treatment of non-steroidal anti-inflammatory agents, which are known to be inhibitors of cyclooxygenases, did not inhibit or instead exaggerated these responses in asthmatics or experimental animal models, indicating that there are regulatory prostanoids in allergic inflammation. Recently, strategies of gene manipulation such as the "knockout" or "transgenic" techniques are important means to understand the role of a certain functional molecule. These approaches and the development of their antagonists/inhibitors could help us to understand the function of prostanoids in the pathophysiology of allergic disorders.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Cytokines; Humans; Hypersensitivity; Hypersensitivity, Immediate; Inflammation; Mast Cells; Prostaglandin D2; Prostaglandins

Topics: Asthma; Bronchial Hyperreactivity; Cytokines; Humans; Prostaglandin D2

Allergen challenge of subjects with asthma produces an early asthmatic response, late asthmatic response, and increases bronchial responsiveness. Histamine partly mediates the early asthmatic response, and may play a role in late-phase responses. Azelastine has antiallergic properties and has been proposed as a treatment for asthma. We therefore investigated the contribution of histamine to late-phase responses with the use of the potent H1-receptor antagonist azelastine.. Ten subjects with atopic asthma were studied in a double-blind, randomized, placebo-controlled trial. Azelastine was administered over 4 days before allergen challenge. Changes in airway caliber were followed with measurements of forced expiratory volume in 1 second, and changes in bronchial responsiveness were followed by methacholine and prostaglandin D2 bronchial provocation tests.. Azelastine significantly inhibited the development of the early asthmatic response. Azelastine had no effect on the late asthmatic response or on the development of allergen-induced increases in bronchial responsiveness. The power of the study was sufficient to have had a high probability of detecting any important differences between placebo and azelastine during the late phase.. Azelastine had no significant effect on the late-phase response model of asthma. This study does not support the hypothesis that histamine is an important mediator of the late asthmatic response or allergen-induced increases in bronchial responsiveness.

Topics: Adult; Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoconstriction; Double-Blind Method; Female; Forced Expiratory Volume; Histamine; Histamine H1 Antagonists; Humans; Male; Methacholine Chloride; Phthalazines; Prostaglandin D2

In allergen-induced asthma, activated mast cells start the lung inflammatory process with degranulation, cytokine synthesis, and mediator release. Bruton's tyrosine kinase (Btk) activity is required for the mast cell activation during IgE-mediated secretion.. This study characterized a novel inhaled Btk inhibitor RN983 in vitro and in ovalbumin allergic mouse models of the early (EAR) and late (LAR) asthmatic response.. RN983 potently, selectively, and reversibly inhibited the Btk enzyme. RN983 displayed functional activities in human cell-based assays in multiple cell types, inhibiting IgG production in B-cells with an IC50 of 2.5 ± 0.7 nM and PGD2 production from mast cells with an IC50 of 8.3 ± 1.1 nM. RN983 displayed similar functional activities in the allergic mouse model of asthma when delivered as a dry powder aerosol by nose-only inhalation. RN983 was less potent at inhibiting bronchoconstriction (IC50(RN983) = 59 μg/kg) than the β-agonist salbutamol (IC50(salbutamol) = 15 μg/kg) in the mouse model of the EAR. RN983 was more potent at inhibiting the antigen induced increase in pulmonary inflammation (IC50(RN983) = <3 μg/kg) than the inhaled corticosteroid budesonide (IC50(budesonide) = 27 μg/kg) in the mouse model of the LAR.. Inhalation of aerosolized RN983 may be effective as a stand-alone asthma therapy or used in combination with inhaled steroids and β-agonists in severe asthmatics due to its potent inhibition of mast cell activation.

Topics: Administration, Inhalation; Adrenergic beta-2 Receptor Agonists; Agammaglobulinaemia Tyrosine Kinase; Albuterol; Animals; Anti-Asthmatic Agents; Anti-Inflammatory Agents; Asthma; B-Lymphocytes; Bronchial Hyperreactivity; Bronchoconstriction; Bronchodilator Agents; Budesonide; Cell Degranulation; Cells, Cultured; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Dry Powder Inhalers; Glucocorticoids; Humans; Immunoglobulin G; Lung; Male; Mast Cells; Mice, Inbred BALB C; Ovalbumin; Phthalazines; Pneumonia; Prostaglandin D2; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyridazines

Prostaglandin D2 (PGD2) causes cough and levels are increased in asthma suggesting that it may contribute to symptoms. Although the prostaglandin D2 receptor 2 (DP2) is a target for numerous drug discovery programmes little is known about the actions of PGD2 on sensory nerves and cough. We used human and guinea pig bioassays, in vivo electrophysiology and a guinea pig conscious cough model to assess the effect of prostaglandin D2 receptor (DP1), DP2 and thromboxane receptor antagonism on PGD2 responses. PGD2 caused cough in a conscious guinea pig model and an increase in calcium in airway jugular ganglia. Using pharmacology and receptor-deficient mice we showed that the DP1 receptor mediates sensory nerve activation in mouse, guinea pig and human vagal afferents. In vivo, PGD2 and a DP1 receptor agonist, but not a DP2 receptor agonist, activated single airway C-fibres. Interestingly, activation of DP2 inhibited sensory nerve firing to capsaicin in vitro and in vivo. The DP1 receptor could be a therapeutic target for symptoms associated with asthma. Where endogenous PGD2 levels are elevated, loss of DP2 receptor-mediated inhibition of sensory nerves may lead to an increase in vagally associated symptoms and the potential for such adverse effects should be investigated in clinical studies with DP2 antagonists.

Topics: Administration, Inhalation; Animals; Bronchial Hyperreactivity; Bronchial Spasm; Capsaicin; Cells, Cultured; Cough; Disease Models, Animal; DNA-Binding Proteins; Guinea Pigs; Humans; Indoles; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Prostaglandin D2; Receptors, Immunologic; Receptors, Prostaglandin; Receptors, Thromboxane; Sensitivity and Specificity; Tissue Culture Techniques; Transcription Factor DP1; Transcription Factors; Vagus Nerve

Sphingosine-1-phosphate (S1P) has been shown to be involved in the asthmatic disease as well in preclinical mouse experimental models of this disease. The aim of this study was to understand the mechanism(s) underlying S1P effects on the lung.. BALB/c, mast cell-deficient and Nude mice were injected with S1P (s.c.) on days 0 and 7. Functional, molecular and cellular studies were performed.. S1P administration to BALB/c mice increased airway smooth muscle reactivity, mucus production, PGD2 , IgE, IL-4 and IL-13 release. These features were associated to a higher recruitment of mast cells to the lung. Mast cell-deficient Kit (W) (-sh/) (W) (-sh) mice injected with S1P did not display airway smooth muscle hyper-reactivity. However, lung inflammation and IgE production were still present. Treatment in vivo with the anti-CD23 antibody B3B4, which blocks IgE production, inhibited both S1P-induced airway smooth muscle reactivity in vitro and lung inflammation. S1P administration to Nude mice did not elicit airway smooth muscle hyper-reactivity and lung inflammation. Naïve (untreated) mice subjected to the adoptive transfer of CD4+ T-cells harvested from S1P-treated mice presented all the features elicited by S1P in the lung.. S1P triggers a cascade of events that sequentially involves T-cells, IgE and mast cells reproducing several asthma-like features. This model may represent a useful tool for defining the role of S1P in the mechanism of action of currently-used drugs as well as in the development of new therapeutic approaches for asthma-like diseases.

Topics: Animals; Bronchial Hyperreactivity; CD4-Positive T-Lymphocytes; Immunoglobulin E; Interleukin-13; Interleukin-4; Lysophospholipids; Mast Cells; Mice, Inbred BALB C; Mice, Knockout; Mice, Nude; Pneumonia; Prostaglandin D2; Sphingosine

Aspergillus fumigatus is often associated in asthmatic patients with the exacerbation of asthma symptoms. The pathomechanism of this phenomenon has not been fully understood. Here, we evaluated the immunological mechanisms and the role of the prostaglandin D2 / Chemoattractant Receptor-Homologous Molecule Expressed on Th2 Cells (CRTH2) pathway in the development of Aspergillus-associated asthma exacerbation. We studied the effects of A. fumigatus on airway inflammation and bronchial hyper-responsiveness in a rat model of chronic asthma. Inhalation delivery of A. fumigatus conidia increased the airway eosinophilia and bronchial hyper-responsiveness in ovalbumin-sensitized, challenged rats. These changes were associated with prostaglandin D2 synthesis and CRTH2 expression in the lungs. Direct inflammation occurred in ovalbumin-sensitized, challenged animals, whereas pre-treatment with an antagonist against CRTH2 nearly completely eliminated the A. fumigatus-induced worsening of airway eosinophilia and bronchial hyper-responsiveness. Our data demonstrate that production of prostaglandin D2 followed by eosinophil recruitment into the airways via a CRTH2 receptor are the major pathogenic factors responsible for the A. fumigatus-induced enhancement of airway inflammation and responsiveness.

Topics: Animals; Anti-Inflammatory Agents; Aspergillus fumigatus; Asthma; Bronchial Hyperreactivity; Disease Models, Animal; Eosinophils; Lung; Male; Ovalbumin; Prostaglandin D2; Pulmonary Aspergillosis; Pulmonary Eosinophilia; Rats; Rats, Wistar; Receptors, Immunologic; Receptors, Prostaglandin; Signal Transduction

Chemoattractant receptor homologous molecule expressed on T helper type 2 cells (CRTH2) is a PGD2 receptor found on eosinophils, basophils, and Th2 type T cells which exhibits chemotaxis and functions in activation cascades. However, while a number of CRTH2 antagonists, including ramatroban, are known to exert activity in certain animal models, activity in a guinea pig model of EA-induced airway hyperresponsiveness has not been demonstrated. The newly developed CRTH2 antagonist ASP5642 has shown antagonistic activity against human and guinea pig CRTH2 in previous studies and has also been found effective in treating guinea pig models of airway inflammation and airway hyperresponsiveness. While previous studies have used animals such as rats and mice to evaluate CRTH2 antagonist effects, ours is the first attempt to evaluate CRTH2 function in a guinea pig asthma model, which may prove useful in evaluating the compound's effects in humans, given the comparable airway function between the two species taken together, these data from the present study strongly suggest the utility of ASP5642 in investigating the role of CRTH2 in inflammatory responses and as a drug treatment for human asthma.

Topics: Animals; Anti-Asthmatic Agents; Anti-Inflammatory Agents; Antigens; Benzhydryl Compounds; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Carbazoles; Cell Count; Eosinophilia; Guinea Pigs; HEK293 Cells; Humans; K562 Cells; Male; Ovalbumin; Pneumonia; Prostaglandin D2; Pyridazines; Receptors, Immunologic; Receptors, Prostaglandin; Sulfonamides

Prostaglandins (PGs) can enhance or suppress inflammation by acting on different receptors expressed by hematopoietic and nonhematopoietic cells. Prostaglandin D(2) binds to the D prostanoid (DP)1 and DP2 receptor and is seen as a critical mediator of asthma causing vasodilation, bronchoconstriction, and inflammatory cell influx. Here we show that inhalation of a selective DP1 agonist suppresses the cardinal features of asthma by targeting the function of lung dendritic cells (DCs). In mice treated with DP1 agonist or receiving DP1 agonist-treated DCs, there was an increase in Foxp3(+) CD4(+) regulatory T cells that suppressed inflammation in an interleukin 10-dependent way. These effects of DP1 agonist on DCs were mediated by cyclic AMP-dependent protein kinase A. We furthermore show that activation of DP1 by an endogenous ligand inhibits airway inflammation as chimeric mice with selective hematopoietic loss of DP1 had strongly enhanced airway inflammation and antigen-pulsed DCs lacking DP1 were better at inducing airway T helper 2 responses in the lung. Triggering DP1 on DCs is an important mechanism to induce regulatory T cells and to control the extent of airway inflammation. This pathway could be exploited to design novel treatments for asthma.

Topics: Alum Compounds; Animals; Asthma; Bronchial Hyperreactivity; Cell Differentiation; Cyclic AMP-Dependent Protein Kinases; Dendritic Cells; Interleukin-10; Lung; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Ovalbumin; Prostaglandin D2; Receptors, Prostaglandin; T-Lymphocytes, Regulatory

Prostaglandins (PGs) are potent proinflammatory mediators generated through arachidonic acid metabolism by cyclooxygenase-1 and -2 (COX-1 and COX-2) in response to different stimuli and play an important role in modulating the inflammatory responses in a number of conditions, including allergic airway inflammation. Thymoquinone (TQ) is the main active constituent of the volatile oil extract of Nigella sativa seeds and has been reported to have anti-inflammatory properties. We examined the effect of TQ on the in vivo production of PGs and lung inflammation in a mouse model of allergic airway inflammation. Mice sensitized and challenged through the airways with ovalbumin (OVA) exhibited a significant increase in PGD2 and PGE2 production in the airways. The inflammatory response was characterized by an increase in the inflammatory cell numbers and Th2 cytokine levels in the bronchoalveolar lavage (BAL) fluid, lung airway eosinophilia and goblet cell hyperplasia, as well as the induction of COX-2 protein expression in the lung. Intraperitoneal injection of TQ for 5 days before the first OVA challenge attenuated airway inflammation as demonstrated by the significant decrease in Th2 cytokines, lung eosinophilia, and goblet cell hyperplasia. This attenuation of airway inflammation was concomitant to the inhibition of COX-2 protein expression and PGD2 production. However, TQ had a slight inhibitory effect on COX-1 expression and PGE2 production. These findings suggest that TQ has an anti-inflammatory effect during the allergic response in the lung through the inhibition of PGD2 synthesis and Th2-driven immune response.

Topics: Allergens; Animals; Anti-Inflammatory Agents; Benzoquinones; Bronchial Hyperreactivity; Cyclooxygenase 1; Cyclooxygenase 2; Cytokines; Dinoprostone; Disease Models, Animal; Female; Gene Expression Regulation; Male; Mice; Mice, Inbred BALB C; Ovalbumin; Prostaglandin D2; Th2 Cells

PGD2, a lipid mediator released from mast cells, is known to participate in allergic reactions. However, the mechanism by which PGD2 contributes to such reactions remains unclear. We established a novel experimental model of asthma that permitted direct assessment of the role of PGD2 in airway inflammation. Antigen-sensitized mice were exposed to aerosolized prostaglandin D2 (PGD2) 1 d before challenge with low-dose aerosolized antigen. Not only the numbers of eosinophils, lymphocytes, and macrophages but also the levels of IL-4 and IL-5 in bronchoalveolar lavage fluid were higher in PGD2-pretreated mice than in control mice. The expression of macrophage-derived chemokine (MDC), a chemoattractant for Th2 cells, was greater in PGD2-pretreated mice than in control. Injection of anti-MDC antibody into PGD2-pretreated mice markedly inhibited inflammatory cell infiltration as well as Th2 cyto-kine production after antigen challenge. These results indicate that PGD2 accelerates Th2 type inflammation by induction of MDC. Our results suggest that this mechanism may play a key role in the development of human asthma and that MDC might be a target molecule for therapeutic intervention.

Topics: Animals; Antigens; Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Cell Line; Chemokine CCL22; Chemokines; Chemokines, CC; Cytokines; Disease Models, Animal; Humans; Lung; Male; Mice; Mice, Inbred BALB C; Prostaglandin D2; Spleen; Th2 Cells

Inhalation of heparin attenuates hyperventilation-induced bronchoconstriction in humans and dogs. The purpose of this study was to determine whether heparin inhibits the late-phase response to hyperventilation, which is characterized by increased peripheral airway resistance (RP), eicosanoid mediator production, neutrophilic/ eosinophilic inflammation, and airway hyperreactivity (AHR) at 5 h after dry air challenge (DAC). Fiberoptic bronchoscopy was used to record RP and airway reactivity (DeltaRP) to aerosol and intravenous histamine before and 5 h after DAC. Bronchoalveolar lavage fluid (BALF) cells and eicosanoid mediators were also measured approximately 5 h after DAC. DAC of vehicle-treated bronchi resulted in late-phase airway obstruction (approximately 120% increase over baseline RP), inflammation, increased BALF concentrations of leukotriene (LT) C(4), LTD(4), and LTE(4) and prostaglandin (PG)D(2), and AHR. Pretreatment with aerosolized heparin attenuated late-phase airway obstruction by approximately 50%, inhibited eosinophil infiltration, reduced BALF concentrations of LTC(4), LTD(4), and LTE(4) and PGD(2), and abolished AHR. We conclude that heparin inhibits hyperventilation-induced late-phase changes in peripheral airway function, and does so in part via the inhibition of eosinophil migration and eicosanoid mediator production and release.

Topics: Administration, Inhalation; Airway Resistance; Animals; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Bronchoscopy; Disease Models, Animal; Dogs; Drug Evaluation, Preclinical; Eicosanoids; Eosinophils; Heparin; Humans; Hyperventilation; Inflammation; Leukotriene C4; Leukotriene D4; Leukotriene E4; Male; Neutrophils; Prostaglandin D2; Time Factors

This study investigated the capacity of conjugated linoleic acids (CLA) to reduce ex vivo antigen-induced release of eicosanoids in a type I hypersensitivity model. Guinea pigs were fed a diet containing 0.25% safflower oil (control) or 0.25% CLA [43% trans (t)10, cis (c)12; 41% c9, t11/t9, c11 18:2] for 2 wk before and during sensitization to ovalbumin (OVA). Lungs, tracheas, and bladders were incubated in physiological saline solution (PSS) for 1 h (basal mediator release) and challenged with OVA (0.01 g/l PSS) for 1 h (mediator release in response to antigen). Eicosanoids were quantified by HPLC/tandem mass spectrometry or enzyme immunoassay. CLA feeding resulted in no change in basal release but decreased eicosanoid release from sensitized tissues in response to antigen challenge in the following manner: thromboxane B(2), 6-keto-prostaglandin (PG)F(1alpha), PGF(2alpha), PGD(2), PGE(2) by 57-75% in lung, 45-65% in trachea, and 38-60% in bladder; and leukotriene C(4)/D(4)/E(4) by 87, 90, and 50% in lung, trachea, and bladder, respectively. These data indicate that feeding CLA reduces lipid-derived inflammatory mediators produced by this type I hypersensitivity model.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blotting, Western; Bronchial Hyperreactivity; Cyclooxygenase 2; Dinoprost; Dinoprostone; Eicosanoids; Female; Guinea Pigs; Hypersensitivity, Immediate; Isoenzymes; Linoleic Acid; Ovalbumin; Prostaglandin D2; Prostaglandin-Endoperoxide Synthases; Trachea; Urinary Bladder

Allergic asthma is caused by the aberrant expansion in the lung of T helper cells that produce type 2 (TH2) cytokines and is characterized by infiltration of eosinophils and bronchial hyperreactivity. This disease is often triggered by mast cells activated by immunoglobulin E (IgE)-mediated allergic challenge. Activated mast cells release various chemical mediators, including prostaglandin D2 (PGD2), whose role in allergic asthma has now been investigated by the generation of mice deficient in the PGD receptor (DP). Sensitization and aerosol challenge of the homozygous mutant (DP-/-) mice with ovalbumin (OVA) induced increases in the serum concentration of IgE similar to those in wild-type mice subjected to this model of asthma. However, the concentrations of TH2 cytokines and the extent of lymphocyte accumulation in the lung of OVA-challenged DP-/- mice were greatly reduced compared with those in wild-type animals. Moreover, DP-/- mice showed only marginal infiltration of eosinophils and failed to develop airway hyperreactivity. Thus, PGD2 functions as a mast cell-derived mediator to trigger asthmatic responses.

Topics: Allergens; Animals; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Crosses, Genetic; Female; Gene Targeting; Humans; Immunoglobulin E; Interferon-gamma; Interleukins; Lung; Lymphocytes; Male; Mast Cells; Mice; Mice, Inbred C57BL; Mucus; Ovalbumin; Prostaglandin D2; Receptors, Immunologic; Receptors, Prostaglandin; Respiratory Mucosa

We tested the hypothesis that mast cells contribute to platelet-activating factor (PAF)-induced airways hyperreactivity and hyperpermeability in mice. Airways reactivity to acetylcholine (ACh) and lung permeability to Evans blue (EB) dye were measured before and after PAF challenge in genetically mast cell-deficient (WBB6F1 W/Wv) and normal congenic (WBB6F1 +/+) mice, as well as mast cell-reconstituted (BMT W/Wv) mice. In addition, prostaglandin D2 (PGD2), a mast cell-specific mediator, was measured in the bronchoalveolar lavage (BAL) from +/+ and W/Wv mice to determine if lung mast cell activation was a consequence of PAF challenge. Genetically PAF-sensitive AKR/J mice were also treated with the mast cell stabilizer nedocromil prior to assessment of PAF effects on ACh reactivity. Intravenous PAF (10 micrograms/kg) induced a significant (P < 0.05) increase in airways reactivity to ACh (25 micrograms/kg) in both +/+ (371 +/- 52%) and W/Wv (122 +/- 24%) mice. There was a significantly greater increase in +/+ compared with W/Wv mice. PAF-induced hyperreactivity to ACh in BMT W/Wv mice (191 +/- 44%) was significantly (P < 0.05) greater than age-matched W/Wv mice (80 +/- 16%), but not significantly different from age-matched +/+ mice (153 +/- 44%). PAF (10 micrograms/kg) also significantly (P < 0.5) increased lung permeability in +/+ and W/Wv mice, but there was no significant difference between groups. BAL PGD2 increased significantly in +/+ mice following PAF challenge (559 +/- 24 ng/ml) compared with vehicle controls (152 +/- 8 pg/ml). There was no significant increase in BAL PGD2 from W/Wv mice. Nedocromil pretreatment significantly (P < 0.05) decreased PAF-induced hyperreactivity in AKR/J mice but not in W/Wv mice (P > 0.05). We conclude that mast cells contribute significantly to PAF-induced hyperreactivity but not hyperpermeability in mice.

Topics: Acetylcholine; Analysis of Variance; Animals; Azepines; Blood Cell Count; Bone Marrow Transplantation; Bronchi; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Evans Blue; Hematocrit; Lung; Male; Mast Cells; Mice; Mice, Inbred AKR; Mice, Mutant Strains; Nedocromil; Permeability; Platelet Activating Factor; Prostaglandin D2; Species Specificity; Trachea; Triazoles

Toluene diisocyanate (TDI) is a volatile, highly reactive chemical widely used as a polymerizing agent in the production of polyurethane foams, lacquers, adhesives, and other items. Repeated airway exposures in the workplace to TDI may cause a concentration-dependent risk of developing chronic airway disorders. Different pathomechanisms are involved. IgE-mediated sensitization and irritative effects were clearly demonstrated in exposed subjects as well as in animals. In this study we examined the cellular and mediator composition in bronchoalveolar lavage fluid (BALF) of guinea pigs (eight in each group) exposed to TDI (10, 20, or 30 ppb) on 5 consecutive days for 2 hours each. Increased numbers of eosinophils and significantly elevated levels of LTB4 and LTC4/LTD4/LTE4 were obtained in BALF of all exposed animals when compared to nonexposed control animals. PGD2 and TXB2 remained unaltered in BALF. Stimulation of BALF cells of exposed and control animals with Ca-ionophore A23187 and arachidonic acid induced an increased generation of LTB4. Furthermore, BALF cells of the exposed animal groups generated immunoreactive LTC4/LTD4/LTE4, whereas controls did not show peptido-leukotriene formation in the presence and absence of stimuli. Our data clearly demonstrate an influx of eosinophils into the airways associated with mediator release and higher cellular responsiveness after TDI exposure.

Topics: Animals; Arachidonic Acid; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Calcimycin; Dose-Response Relationship, Drug; Eosinophils; Female; Guinea Pigs; Inflammation Mediators; Leukocyte Count; Leukotrienes; Prostaglandin D2; Thromboxane B2; Toluene 2,4-Diisocyanate

Interaction among mediators such as bradykinin (BK), histamine (H), and prostaglandin (PG) D2 may contribute to reduction in airway caliber in asthma. Ten stable asthmatic subjects took part in a study to investigate possible mediator interaction. The provocative concentration of mediator required to reduce forced expiratory volume in 1 s (FEV1) by 12.5% from the starting baseline value (PC12.5) and that required to reduce the fall in FEV1 from 12.5 to 25% (PC25-12.5) of H, BK, and PGD2 were determined. On three subsequent occasions, subjects inhaled either the vehicle plus BK PC12.5 or the vehicle plus H or PGD2 PC25-12.5, and FEV1 was measured at regular time intervals up to 40 min. Predicted time course curves were calculated from these results. On two additional occasions, interactive time course studies were undertaken when the subject inhaled BK PC12.5 followed by H or PGD2 PC25-12.5. On a further three visits, the time courses of individual mediators were studied. When BK was combined with H and PGD2, the maximum fall in FEV1 and the rate of recovery after inhalation of the second mediator were not significantly different from those values of predicted time course responses for the same combination of mediator. Thus, by employing pharmacologically active concentrations of inhaled BK, H, and PGD2, which act through separate receptor mechanisms, we were unable to demonstrate any pharmacological interaction on airway caliber in asthma.

Topics: Adult; Aerosols; Aged; Asthma; Bradykinin; Bronchial Hyperreactivity; Dose-Response Relationship, Drug; Female; Forced Expiratory Volume; Histamine; Humans; Male; Prostaglandin D2; Skin Tests

To determine if late asthmatic response (LAR) is associated with hyperresponsiveness of airway smooth muscle itself, we performed antigen challenge in dogs treated with Metopirone. We studied the contractile response to acetylcholine (ACh) in isolated bronchial and bronchiolar segments 8 h after either saline inhalation (the control group) or antigen challenge in dogs demonstrating immediate asthmatic response (IAR) alone and in dogs demonstrating both IAR and LAR. Airway responses to Ascaris suum antigen were assessed by changes in respiratory resistance measured with the forced oscillation technique at 3 Hz. Concentration-response curves of bronchial preparations to ACh did not differ significantly among three groups consisting of the control, IAR and LAR. However, the contractile response of bronchiolar preparations to ACh was significantly greater in the LAR group when compared to the control and IAR groups at the concentrations of ACh ranging from 10(-6) to 3 x 10(-4) M (p < 0.01). SQ 29548, a receptor antagonist of thromboxane A2 and prostaglandin D2 (PGD2), inhibited LAR-induced hyperresponsiveness to ACh in a concentration-dependent fashion. The bronchiolar preparations obtained from dogs showing LAR contained a significantly higher amount of PGD2 than those obtained from dogs showing IAR alone (p < 0.01, n = 6). These results suggest that LAR is associated with hyperresponsiveness of peripheral airway smooth muscle to ACh, and this augmented response to ACh mediates via PGD2 released during LAR.

Topics: Acetylcholine; Airway Resistance; Animals; Asthma; Bronchial Hyperreactivity; Disease Models, Animal; Dogs; Hydrocortisone; Muscle Contraction; Muscle, Smooth; Prostaglandin D2

Prostaglandin D2 (PGD2) and thromboxane A2 (TXA2) have been suggested to play important roles in the pathogenesis of bronchial asthma. In the present study, effects of i.v.-administration of PGD2 on bronchial hyperresponsiveness in guinea pigs were investigated by the measurement of dynamic compliance and dynamic respiratory resistance with formulae which can exclude the effects of changes of the airway wall thickness. With these formulae, the ratio of bronchial smooth muscle constriction by histamine can be estimated as an index of bronchial hyperresponsiveness. Administration of PGD2 induced airway wall edema. The ratio of bronchial smooth muscle constriction by histamine was enhanced with the administration of PGD2. Moreover, TXA2 antagonists, ONO-NT-126 and ONO-8809, inhibited the effect of PGD2 administration.

Topics: Airway Resistance; Animals; Asthma; Bridged Bicyclo Compounds; Bronchial Hyperreactivity; Edema; Fatty Acids, Monounsaturated; Guinea Pigs; Histamine; Infusions, Intravenous; Male; Muscle Contraction; Muscle, Smooth; Prostaglandin D2; Thromboxane A2