leukotriene-b4 and Bronchial-Hyperreactivity

The contribution of CD8+ T cells to the development of airway hyperresponsiveness and airway inflammation has received increased attention recently. CD8+ T cells, which are capable of secreting TH2 cytokines, including IL-4, IL-5, and IL-13, have been described in asthmatic subjects and in animals sensitized and challenged with allergen. A subset of these IL-13-producing CD8+ T cells, effector memory CD8+ T cells in the mouse, express a high-affinity receptor for leukotriene B4 (BLT1), and expression of this receptor is essential for their accumulation in the lung and development of airway hyperresponsiveness and airway inflammation. A similar subset of CD8+/BLT1+/IL-13+ T cells has also been identified in the bronchoalveolar lavage fluid of asthmatic subjects, suggesting a pathogenic role for this unique subset of CD8+ T cells in asthma.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; CD8-Positive T-Lymphocytes; Cytokines; Disease Models, Animal; Disease Progression; Humans; Leukotriene B4; Mice

Leukotrienes (i.e., products of the 5-lipoxygenase pathway) are thought to be contributors to lung pathologies. Moreover, eosinophils have been linked with pulmonary leukotriene activities both as potential sources of these mediators and as responding effector cells. The objective of the present study was to define the role(s) of leukotrienes in the lung pathologies accompanying eosinophil-associated chronic respiratory inflammation. A transgenic mouse model of chronic T helper (Th) 2-driven inflammation expressing IL-5 from T cells and human eotaxin-2 locally in the lung (I5/hE2) was used to define potential in vivo relationships among eosinophils, leukotrienes, and chronic Th2-polarized pulmonary inflammation. Airway levels of cys-leukotrienes and leukotriene B4 (LTB4) are both significantly elevated in I5/hE2 mice. The eosinophil-mediated airway hyperresponsiveness (AHR) characteristic of these mice was abolished in the absence of leukotrienes (i.e., 5-lipoxygenase-deficient I5/hE2). More importantly, the loss of leukotrienes led to an unexpectedly significant decrease in collagen deposition (i.e., pulmonary fibrosis) that accompanied elevated levels of IL-4/-13 and TGF-β in the lungs of I5/hE2 mice. Further studies using mice deficient for the LTB4 receptor (BLT-1(-/-)/I5/hE2) and I5/hE2 animals administered a cys-leukotriene receptor antagonist (montelukast) demonstrated that the AHR and the enhanced pulmonary fibrosis characteristic of the I5/hE2 model were uniquely cys-leukotriene-mediated events. These data demonstrate that, similar to allergen challenge models of wild-type mice, cys-leukotrienes underlie AHR in this transgenic model of severe pulmonary Th2 inflammation. These data also suggest that an underappreciated link exists among eosinophils, cys-leukotriene-mediated events, and fibrotic remodeling associated with elevated levels of IL-4/-13 and TGF-β.

Topics: Animals; Arachidonate 5-Lipoxygenase; Bronchial Hyperreactivity; Chemokine CCL24; Disease Models, Animal; Eosinophils; Humans; Interleukin-5; Leukotriene B4; Leukotrienes; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Pneumonia; Pulmonary Fibrosis; Receptors, Leukotriene B4; Th2 Cells

Bronchial hyperresponsiveness is a hallmark of asthma and many factors modulate bronchoconstriction episodes. A potential correlation of formaldehyde (FA) inhalation and asthma has been observed; however, the exact role of FA remains controversial. We investigated the effects of FA inhalation on Ovalbumin (OVA) sensitisation using a parameter of respiratory mechanics. The involvement of nitric oxide (NO) and cyclooxygenase-derived products were also evaluated. The rats were submitted, or not, to FA inhalation (1%, 90 min/day, 3 days) and were OVA-sensitised and challenged 14 days later. Our data showed that previous FA exposure in allergic rats reduced bronchial responsiveness, respiratory resistance (Rrs) and elastance (Ers) to methacholine. FA exposure in allergic rats also increased the iNOS gene expression and reduced COX-1. L-NAME treatment exacerbated the bronchial hyporesponsiveness and did not modify the Ers and Rrs, while Indomethacin partially reversed all of the parameters studied. The L-NAME and Indomethacin treatments reduced leukotriene B₄ levels while they increased thromboxane B₂ and prostaglandin E₂. In conclusion, FA exposure prior to OVA sensitisation reduces the respiratory mechanics and the interaction of NO and PGE₂ may be representing a compensatory mechanism in order to protect the lung from bronchoconstriction effects.

Topics: Administration, Inhalation; Airway Resistance; Animals; Anti-Inflammatory Agents, Non-Steroidal; Bronchial Hyperreactivity; Bronchoconstrictor Agents; Cyclooxygenase 1; Dinoprostone; Disease Models, Animal; Eicosanoids; Formaldehyde; Gene Expression Regulation, Enzymologic; Leukotriene B4; Male; Membrane Proteins; Nitric Oxide; Nitric Oxide Synthase Type II; Rats; Rats, Wistar; Respiratory Insufficiency; Respiratory Mucosa; Thromboxane B2

Allergic asthma is characterized by reversible airway obstruction, lung inflammation, and airway hyperresponsiveness (AHR). Previous studies using leukotriene B(4) (LTB(4)) receptor 1-deficient mice and adoptive transfer experiments have suggested that LTB(4) plays a role in lung inflammation and AHR.. In this study, we used a leukotriene A(4) hydrolase (LTA(4)H) inhibitor as a pharmacological tool to directly examine the role of LTB(4) in a mast cell-dependent murine model of allergic airway inflammation.. We used the forced oscillation technique to test the effects of an LTA(4)H inhibitor dosed during the challenge phase on AHR. Lung tissue and lavage were collected for analysis.. Treatment with an LTA(4)H inhibitor improved multiple parameters encompassing AHR and lung function. Significant decreases in inflammatory leukocytes, cytokines, and mucin were observed in the lung lumen. Serum levels of antigen-specific IgE and IgG1 were also decreased. Labeled antigen uptake by lung dendritic cells and subsequent trafficking to draining lymph nodes and the lung were decreased on LTA(4)H inhibitor treatment. Provocatively, inhibition of LTA(4)H increased lipoxin A(4) levels in lung lavage fluid.. These data suggest that LTB(4) plays a key role in driving lung inflammation and AHR. Mechanistically, we provide evidence that inhibition of LTA(4)H, affects recruitment of both CD4(+) and CD8(+) T cells, as well as trafficking of dendritic cells to draining lymph nodes, and may beneficially modulate other pro- and antiinflammatory eicosanoids in the lung. Inhibition of LTA(4)H is thus a potential therapeutic strategy that could modulate key aspects of asthma.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Cells, Cultured; Cytokines; Epoxide Hydrolases; Immunoglobulin E; Leukotriene B4; Mast Cells; Mice; Mice, Inbred BALB C; Mucins; Ovalbumin

Previous studies have shown that leukotriene B4 (LTB4), a proinflammatory lipid mediator, is linked to the development of airway hyperresponsiveness through the accumulation of IL-13-producing CD8+ T cells, which express a high affinity receptor for LTB4, BLT1 (Miyahara et al., Am J Respir Crit Care Med 2005;172:161-167; J Immunol 2005;174:4979-4984). By using leukotriene A4 hydrolase-deficient (LTA4H-/-) mice, which fail to synthesize LTB4, we determined the role of this lipid mediator in allergen-induced airway responses. Two approaches were used. In the first, LTA4H-/- mice and wild-type (LTA4H+/+) mice were systemically sensitized and challenged via the airways to ovalbumin. In the second, mice were passively sensitized with anti-ovalbumin IgE and exposed to ovalbumin via the airways. Mast cells were generated from bone marrow of LTA4H+/+ mice or LTA4H-/- mice. After active sensitization and challenge, LTA4H-/- mice showed significantly lower airway hyperresponsiveness compared with LTA4H+/+ mice, and eosinophil numbers and IL-13 levels in the bronchoalveoloar lavage of LTA4H-/- mice were also significantly lower. LTA4H-/- mice also showed decreased airway reactivity after passive sensitization and challenge. After LTA4H+/+ mast cell transfer, LTA4H-/- mice showed increased airway reactivity after passive sensitization and challenge, but not after systemic sensitization and challenge. These data confirm the important role for LTB4 in the development of altered airway responses and suggest that LTB4 secretion from mast cells is critical to eliciting increased airway reactivity after passive sensitization with allergen-specific IgE.

Topics: Allergens; Animals; Bone Marrow Cells; Bronchial Hyperreactivity; CD8-Positive T-Lymphocytes; Cytokines; Female; Immunoglobulin E; Inflammation; Interleukin-13; Leukotriene B4; Lipids; Mast Cells; Mice; Mice, Transgenic

Exercise-induced bronchospasm (EIB) occurs in athletes with and without asthma. Studies have suggested an inflammatory basis for EIB in asthmatics; however whether inflammation plays a similar role in EIB in athletes without asthma remains unclear. Our objective was to determine whether there is evidence of an inflammatory basis for exercise-induced bronchospasm occurring in non-asthmatic athletes. Ninety-six athletes without asthma from varsity college teams underwent eucapnic voluntary hyperventilation testing. Sputum was induced from subjects with hypertonic saline inhalation post-eucapnic voluntary hyperventilation testing and was analyzed with enzyme-linked immunosorbent assays for IL-5, IL-8, IL-13, cysteinyl-leukotrienes, prostaglandin E2, histamine, leukotriene B4, and thromboxane B2. In addition, inflammatory (neutrophils, lymphocytes, eosinophils, and macrophages) and epithelial cell counts in sputum were recorded. Multivariate regression modeling showed a significant correlation between concentrations of select inflammatory mediators after eucapnic voluntary hyperventilation testing and severity of EIB. Means of the log-transformed concentrations of inflammatory mediators in EIB-positive athletes were significantly higher post-eucapnic voluntary hyperventilation than in EIB-negative athletes. Similar findings were not demonstrated with inflammatory cells. Concentrations of inflammatory mediators are higher in EIB-positive athletes than in EIB-negative athletes without asthma after eucapnic voluntary hyperventilation testing. The severity of EIB in our cohort also is significantly correlated with increased concentrations of select inflammatory mediators suggesting a potential inflammatory basis for EIB in athletes without asthma.

Topics: Adult; Age Factors; Asthma; Asthma, Exercise-Induced; Bronchial Hyperreactivity; Cohort Studies; Dinoprostone; Female; Histamine; Humans; Incidence; Inflammation; Inflammation Mediators; Leukotriene B4; Male; Multivariate Analysis; Probability; Respiratory Function Tests; Risk Assessment; Sensitivity and Specificity; Sex Factors; Sports; Sputum; Thromboxane B2

RBx 7796, a 5-lipoxygenase inhibitor, was evaluated in in vivo efficacy models, in vitro ADME and in vivo pharmacokinetic models.. RBx 7796 was evaluated for inhibition of 5-lipoxygenase enzyme and release of LTB4 from isolated rat and human neutrophils. RBx 7796 was tested in allergic bronchoconstriction model in Balb/c mice and LPS induced airway hyperreactivity model in rats. RBx 7796 was evaluated for metabolic stability in liver microsomes and cytochrome P450 inhibition potential. Pharmacokinetic profile of RBx 7796 was also determined in rat and dog.. RBx 7796 inhibited 5-lipoxygenase enzyme and inhibited release of LTB4 from neutrophils. RBx 7796 also inhibited early and late airway reactivity following allergen challenge in mouse model. LPS induced increase in airway reactivity was blocked by RBx 7796. Compound was found to be stable in liver microsomes and devoid of major cytochrome P450 inhibition potential. The oral bioavailability of RBx 7796 in rat and dog was 83 % and 47 %, respectively. Following repeated daily administration, compound did not exhibit any sign of accumulation and/or tendency to induce its own metabolism.. The results suggest that RBx 7796 is an inhibitor of 5-lipoxygenase enzyme that is orally efficacious in two different models of airway reactivity. The molecule also demonstrated acceptable pharmacokinetic profile warranting further development.

Topics: Animals; Arachidonate 5-Lipoxygenase; Bronchial Hyperreactivity; Calcimycin; Dogs; Humans; Hydroxyurea; Ionophores; Leukotriene B4; Lipopolysaccharides; Lipoxygenase Inhibitors; Male; Mice; Mice, Inbred BALB C; Neutrophils; Rats; Rats, Wistar; Salts

Studies in both humans and rodents have suggested that CD8+ T cells contribute to the development of airway hyperresponsiveness (AHR) and that leukotriene B4 (LTB4) is involved in the chemotaxis of effector CD8+ T cells (T(EFF)) to the lung by virtue of their expression of BLT1, the receptor for LTB4. In the present study, we used a mast cell-CD8-dependent model of AHR to further define the role of BLT1 in CD8+ T cell-mediated AHR. C57BL/6+/+ and CD8-deficient (CD8-/-) mice were passively sensitized with anti-OVA IgE and exposed to OVA via the airways. Following passive sensitization and allergen exposure, C57BL/6+/+ mice developed altered airway function, whereas passively sensitized and allergen-exposed CD8-/- mice failed to do so. CD8-/- mice reconstituted with CD8+ T(EFF) developed AHR in response to challenge. In contrast, CD8-/- mice reconstituted with BLT1-deficient effector CD8+ T cells did not develop AHR. The induction of increased airway responsiveness following transfer of CD8+ T(EFF) or in wild-type mice could be blocked by administration of an LTB4 receptor antagonist confirming the role of BLT1 in CD8+ T cell-mediated AHR. Together, these data define the important role for mast cells and the LTB4-BLT1 pathway in the development of CD8+ T cell-mediated allergic responses in the lung.

Topics: Adoptive Transfer; Animals; Bronchial Hyperreactivity; CD8-Positive T-Lymphocytes; Female; Interleukin-13; Leukotriene B4; Mast Cells; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Receptors, Antigen, T-Cell; Receptors, IgE; Receptors, Leukotriene B4; Receptors, Purinergic P2

An increasing prevalence of allergic diseases, such as atopic dermatitis, allergic rhinitis and bronchial asthma, has been noted worldwide. Allergic asthma strongly correlates with airway inflammation caused by the unregulated production of cytokines secreted by allergen-specific type-2 T helper (Th2) cells. This study aims to explore the therapeutic effect of the airway gene transfer of IL-12, IL-10 and TGF-beta on airway inflammation in a mouse model of allergic asthma.. BALB/c mice were sensitized to ovalbumin (OVA) by intraperitoneal injections with OVA and challenged by nebulized OVA. Different cytokine gene plasmids or non-coding vector plasmids were instilled daily into the trachea up to one day before the inhalatory OVA challenge phase.. Intratracheal administration of IL-10, IL-12 or TGF-beta can efficiently inhibit antigen-induced airway hyper-responsiveness and is able to largely significantly lower the number of eosinophils and neutrophils in bronchoalveolar lavage fluid of ovalbumin (OVA) sensitized and challenged mice during the effector phase. Furthermore, the effect of IL-10 plasmids is more remarkable than any other cytokine gene plasmid. On the other hand, local administration of IL-4 gene plasmids before antigen challenge can induce severe airway hyper-responsiveness (AHR) and airway eosinophilia.. Our data demonstrated that anti-inflammatory cytokines, particularly IL-10, have the therapeutic potential for the alleviation of airway inflammation in murine model of asthma.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Chemokine CCL11; Chemokines, CC; Disease Models, Animal; Female; Gene Transfer Techniques; Interleukin-10; Interleukin-12; Interleukin-4; Leukotriene B4; Mice; Mice, Inbred BALB C; Ovalbumin; Pulmonary Eosinophilia; Transforming Growth Factor beta

Late-phase airway hyperresponsiveness (AHR) in asthma is considered the event leading to persistent inflammation in the lungs, but the molecular mechanisms involved in this process are poorly understood.. To examine the role of TNF-alpha in the development of a late AHR and airway inflammation in asthma.. We established a murine model of asthma with not only biphasic AHR to methacholine but also airway eosinophilia. The effect of TNF-alpha blockade was determined by using anti-TNF-alpha antibody and TNF-alpha knockout mice. Cytosolic phospholipase A(2) (cPLA(2)) mRNA expression and activity were assessed by using RT-PCR and 1-stearoyl-2-[1-(14)C] arachidonyl-sn-glycero-3-phosphocholine as the substrate, respectively.. TNF-alpha blockade resulted in significant inhibition of the late AHR without affecting the early AHR, and reduction in airway eosinophilia and inflammation. cPLA(2) activity was increased in asthmatic lungs in a TNF-alpha-dependent way, and cPLA(2) inhibitor blocked late AHR and airway eosinophilia. TNF-alpha also stimulated the synthesis of cPLA(2) metabolites such as leukotriene B(4) and platelet-activating factor in the airway. Specific inhibitors of cPLA(2) metabolites inhibited the late AHR and airway eosinophilia.. TNF-alpha is the proximal key cytokine capable of developing late-phase AHR and subsequent airway inflammation through expression/activation of cPLA(2).

Topics: Animals; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Bronchoconstrictor Agents; Cytosol; Disease Models, Animal; Enzyme Activation; Histamine; Inflammation; Leukotriene B4; Male; Methacholine Chloride; Mice; Mice, Inbred BALB C; Mice, Knockout; Phospholipases A; Platelet Activating Factor; Pulmonary Eosinophilia; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tumor Necrosis Factor-alpha

Bronchial asthma is an increasingly common disorder that remains poorly understood and difficult to manage. The disease is characterized by airway hyperresponsiveness, chronic inflammation, and mucus overproduction. Based on the finding that leukotriene B4 receptor 1 (BLT1) is expressed highly in Th2 lymphocytes, we analyzed the roles of BLT1 using an OVA-induced bronchial asthma model. BLT1-null mice did not develop airway hyperresponsiveness, eosinophilic inflammation, and hyperplasia of goblet cells. Attenuated symptoms were accompanied by reduced IgE production, and accumulation of IL-5 and IL-13 in bronchoalveolar lavage fluid, suggesting attenuated Th2-type immune response in BLT1-null mice. Peribronchial lymph node cells of sensitized BLT1-null mice showed much attenuated proliferation and production of Th2 cytokines upon re-stimulation with Ag in vitro. Thus, LTB4-BLT1 axis is required for the development of Th2-type immune response, and blockade of LTB4 functions through BLT1 would be novel and useful in the effort to ameliorate bronchial asthma and related Th2-biased immune disorders.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Calcium; Disease Models, Animal; Immunity, Innate; Immunoglobulin E; Leukotriene B4; Lung; Mice; Mice, Knockout; Peroxidase; Receptors, Leukotriene B4; Respiratory System; Th2 Cells

Smoking is the most important cause of chronic obstructive pulmonary disease (COPD). However, the influence of cigarette smoking on the pathogenesis of asthma in the elderly remains controversial. This study attempted to clarify the influence of cigarette smoking on elderly asthmatics.. Forty-eight asthmatics over 70 years old (25 ex-smokers and 23 never-smokers) and 20 patients with COPD over 70 years old (all ex-smokers) were studied to determine the influence of cigarette smoking on IgE-mediated allergy (total IgE, IgE antibodies against inhalant allergens, bronchial hyper-responsiveness (BHR), generation of leukotriene (LT) B4 and C4), pulmonary function, and the relative area of lung showing attenuation values less than -950 Hounsfield units (RA950) on high-resolution computed tomography scans.. The incidence of positive IgE antibodies against inhalant allergens, BHR, and the generation of leukotriene B4 (LTB4) by leucocytes were significantly increased in patients with a history of smoking compared with those without. Residual volume (%RV) was significantly increased, and diffusing capacity for carbon monoxide was significantly decreased in ex-smokers with asthma and COPD compared with never-smokers with asthma. Inspiratory RA950 and ratio of expiratory RA950 to inspiratory RA950 were significantly larger in asthmatics with a smoking history than in those without, and in COPD patients than in asthmatics.. Cigarette smoking enhances the production of IgE antibodies, BHR, and generation of LTB4 by leucocytes in elderly asthmatics. Increased hyper-inflation or emphysematous changes of the lungs expressed by increased RA950, closely related to %RV, was more frequently observed in ex-smokers compared with never-smokers.

Topics: Aged; Asthma; Bronchial Hyperreactivity; Case-Control Studies; Chi-Square Distribution; Female; Humans; Immunoglobulin E; Leukocytes; Leukotriene B4; Leukotriene C4; Male; Pulmonary Diffusing Capacity; Pulmonary Disease, Chronic Obstructive; Respiratory Function Tests; Smoking; Tomography, X-Ray Computed

LY29311 Na, 2-[2-propyl-3-[3-[2-ethyl-4-(4-fluorophenyl)-5-hydroxyphenoxy] propoxy] -phenoxy]-benzoic acid sodium salt, is a novel leukotriene B4 (LTB4) receptor antagonist. Its effects on guinea pig models of asthma were compared with those of dexamethasone.. Effects of LY293111Na were tested in antigen (ovalbumin, OA)-induced bronchial hyperresponsiveness (BHR) and leukocyte accumulation in actively sensitized guinea pigs. Its effects on antigen-induced acute bronchoconstriction in passively sensitized guinea pigs were also studied.. LY293111 Na (10 to 30 mg/kg p.o., 1 h before and 6 h after OA challenge) inhibited BHR to acetylcholine. LY293111 Na (3 mg/kg p. o.) significantly inhibited accumulation of neutrophils in bronchoalveolar lavage (BAL) fluid 24 h after antigen challenge but it did not inhibit accumulation of eosinophils and macrophages at any doses used. In contrast, dexamethasone (30 mg/kg p.o., 4 h before OA challenge) not only inhibited BHR but also reduced the infiltration of all three types of leukocytes. A significant increase of LTB4 levels in BAL fluid was noted at 3 and 15 min after the antigen challenge. LY293111Na did not inhibit antigen-induced acute bronchoconstriction in passively sensitized guinea pigs.. These results indicate that LTB4 may participate in antigen-induced BHR but not in eosinophil infiltration and acute bronchoconstriction in guinea pigs.

Topics: Acetylcholine; Animals; Benzoates; Bronchial Hyperreactivity; Bronchoconstriction; Dexamethasone; Guinea Pigs; Leukocytes; Leukotriene Antagonists; Leukotriene B4; Male; Receptors, Leukotriene B4

Leukotrienes (LTs) are pro-inflammatory mediators that contribute to the pathophysiological features of asthma. The relationship between the amounts of LTB4 and LTC4 produced by the leukocytes of asthmatic patients on the one hand and immunoglobulin E (IgE)-mediated allergy, asthma exacerbations and bronchial hyperresponsiveness was studied. Leukocytes were obtained from peripheral blood drawn from 29 atopic and 27 nonatopic asthmatics during exacerbations and clinically controlled periods, as well as from 20 control individuals. The leukocytes were stimulated with calcium ionophore A23187 to induce LTB4 and LTC4 production. Allergy was assessed by means of specific serum IgE or by positive skin tests, whereas bronchial hyperresponsiveness was measured by methacholine challenge. The leukocytes of the asthmatics generated significantly more LTB4 (p<0.05) and LTC4 (p<0.01) than those of controls. The leukocytes of patients with atopic asthma generated significantly more LTC4 than those of patients with nonatopic asthma (p<0.01). Significantly more LTC4 was produced by leukocytes obtained during exacerbations, than by those obtained during clinically controlled periods (p<0.01). In addition, there was a significant correlation between LTB4 generation by leukocytes and the degree of bronchial hyperresponsiveness to methacholine (r=-0.792, p<0.0001). These results suggest that leukotriene C4 production by leukocytes is associated with immunoglobulin E-mediated allergy and asthma exacerbations, and further that generation of leukotriene B4 is closely related to bronchial hyperresponsiveness in patients with asthma.

Topics: Asthma; Bronchial Hyperreactivity; Female; Humans; Leukocytes; Leukotriene B4; Leukotriene C4; Male; Middle Aged

Repeated intranasal administration of interleukin 8 (IL-8) induces bronchial hyperresponsiveness (BHR) accompanied by lower airway neutrophil accumulation (ANA) in guinea-pigs. Leukotriene B4 (LTB4) is a chemotactic factor for neutrophils. To elucidate whether LTB4 and neutrophil elastase are involved in the IL-8-induced BHR and ANA, the effects of a LTB4 antagonist (ONO-4057) and a neutrophil elastase inhibitor (ONO-5046) on the responses were examined. IL-8 (5 microg x kg[-1]) was administered intranasally to guinea-pigs twice weekly for 3 weeks. One day after the last administration, animals were anaesthetized and artificially ventilated through tracheal cannulae, and lateral pressure at the tracheal cannula (Pao) was measured as an overall index of airway responses to inhaled histamine. ONO-4057 (2 or 20 mg x kg[-1]) or ONO-5046 (30 or 300 mg x kg[-1]) was administered intraperitoneally 24 and 1 h before anaesthesia. ONO-4057, but not ONO-5046, significantly inhibited the IL8-induced BHR and ANA, assessed by bronchoalveolar lavage, in a dose-dependent manner. These findings suggest that interleukin 8 causes bronchial hyperresponsiveness and airway neutrophil accumulation in guinea-pigs in vivo. In part this appears to be due to release of leukotriene B4, whereas it may not be mediated by neutrophil elastase.

Topics: Animals; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Cell Movement; Glycine; Guinea Pigs; Immunosuppressive Agents; Interleukin-8; Leukocyte Elastase; Leukotriene B4; Male; Neutrophils; Phenylpropionates; Sulfonamides

To test the hypothesis that leukotriene (LT) B4 antagonists may be clinically useful in the treatment of asthma, CP-105,696 was evaluated in vitro, using chemotaxis and flow cytometry assays, and in vivo, using a primate asthma model. CP-105,696 inhibited LTB4-mediated monkey neutrophil chemotaxis (isolated cells, LTB4 = 5 nM) and CD11b upregulation (whole blood, LTB4 = 100 nM) with IC50 values of 20 nM and 16.5 microM, respectively. Using a modification of a previously described in vivo protocol (Turner et al. Am. J. Respir. Crit. Care Med. 1994. 149: 1153-1159), we observed that treatment with CP-105,696 inhibited the acute increase in bronchoalveolar lavage (BAL) levels of IL-6 and IL-8 by 56.9 +/- 13.2% and 46.9 +/- 14.5%, respectively, 4 h after challenge with Ascaris suum antigen (Ag). CP-105,696 tended to reduce the increase in BAL protein levels 0.5 h after Ag challenge by 47.5 +/- 18.3%, but this was not statistically significant. In addition, CP-105,696 prevented the significant 11-fold increase in airway responsiveness to methacholine after multiple Ag challenge. These results suggest that LTB4 partially mediates acute and chronic responses to antigen in an experimental primate asthma model and support the clinical evaluation of LTB4 antagonists in human asthma.

Topics: Animals; Asthma; Benzopyrans; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Carboxylic Acids; Chemotaxis, Leukocyte; Humans; Leukotriene B4; Macaca fascicularis; Macrophage-1 Antigen; Neutrophils; Receptors, Leukotriene B4; Up-Regulation

To determine the role of neutrophil elastase in asthmatic responses, we studied the effect of ONO-5046, a specific neutrophil elastase inhibitor, on antigen-induced asthmatic responses in allergic sheep. Pulmonary resistance (RL) was measured for 8 h after antigen challenge. Measurements of airway responsiveness to methacholine and bronchoalveolar lavage fluid (BALF) were obtained 8 h after challenge. Antigen challenge caused early and late increases in RL, airway hyperresponsiveness (AHR), and recruitment of neutrophils and eosinophils along with increases in TXB2 and LTB4 in BALF. ONO-5046 treatment significantly reduced both early and late bronchoconstriction, neutrophil recruitment, increases in LTB4 in BALF, and AHR. ONO-5046 post-treatment significantly reduced the increase in RL 8 h after antigen challenge. Another neutrophil elastase inhibitor, FR 134043, significantly reduced both early and late bronchoconstriction. ONO-5046 had little effect on calcium ionophore-induced LTB4 release from isolated neutrophils and whole blood obtained from drug-treated sheep. These findings suggest that neutrophil elastase is involved in antigen-induced bronchoconstriction and AHR mediated by neutrophil accumulation and 5-lipoxygenase products in allergic sheep.

Topics: Airway Resistance; Animals; Antigens; Asthma; Benzoquinones; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Bronchoconstriction; Calcimycin; Glycine; Heterocyclic Compounds; Leukocyte Elastase; Leukocytes; Leukotriene B4; Masoprocol; Methacholine Chloride; Pancreatic Elastase; Polycyclic Compounds; Sheep; Sulfonamides; Thromboxane B2

To determine whether nasal allergic symptoms can cause bronchial hyperresponsiveness to methacholine, 30 subjects with allergic rhinitis (22 with allergic rhinitis and 8 with allergic asthmatic rhinitis) were studied. All subjects were skin test positive to Dermatophagoides pteronyssinus (DP) and underwent nasal allergic provocation with DP. After provocation, there was a severe nasal allergic reaction in the challenged nostril with a significant increase in nasal resistance both immediately and long (7 h) after DP exposure. There were no significant changes in the forced expiratory volume in 1 s and the forced expiratory flow rate between 25 and 75% of the forced vital capacity and in both allergic rhinitis and allergic asthmatic rhinitis patients. There was also no change in bronchial hyperresponsiveness to methacholine. The eosinophil counts, leukotriene B4, leukotriene C4 and platelet-activating factor levels in nasal discharges also showed no differences in both groups of patients. Our studies suggest that nasal provocation with limited allergen is a safe diagnostic technique. However, the relationship between nasal resistance and airway hyperreactivity is not obvious in this study. The similar concentrations of nasal inflammatory mediators in both allergic rhinitis and allergic asthmatic rhinitis indicate that bronchial hyperreactivity is not solely due to nasal drainage of inflammatory mediators.

Topics: Adolescent; Adult; Allergens; Antigens, Dermatophagoides; Bronchial Hyperreactivity; Eosinophils; Female; Glycoproteins; Humans; Leukocyte Count; Leukotriene B4; Leukotriene C4; Male; Methacholine Chloride; Nasal Mucosa; Nasal Provocation Tests; Platelet Activating Factor; Rhinitis, Allergic, Perennial

The (+/-)-3'-hydroxyfarrerol (IdB 1031) is a new drug endowed with an interesting mucokinetic activity. In this study the effectiveness of IdB 1031 has been verified in a model of airway hyperreactivity and lung inflammation induced in anaesthetized guinea pig by active cigarette smoke exposure. IdB 1031 (500 mg/kg per os) completely inhibited the capacity of cigarette smoke to induce airway hyperreactivity. IdB 1031 also inhibited the recruitment of proinflammatory cells within the airway lumen as showed in bronchoalveolar lavage fluids. In line with these experiments IdB 1031 inhibited 5-lipoxygenase with an IC50 of 7.36 x 10(-6) M in human leukocytes challenged by A-23187 (2 microM). A significant reduction of the above parameters was observed also in animals exposed to smoke after repeated treatment with IdB 1031 at 200 mg/kg per os for 15 days. These results show that IdB 1031 is a promising drug with a favourable spectrum of activities on the respiratory tract.

Topics: Anesthesia; Animals; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Dose-Response Relationship, Drug; Eosinophils; Flavonoids; Guinea Pigs; Humans; Immunoenzyme Techniques; In Vitro Techniques; Leukotriene B4; Lipoxygenase Inhibitors; Macrophages; Male; Neutrophils; Smoking

Nedocromil sodium, a disodium salt of a pyroquinolinedicarboxylic acid, raises the bronchial hyperresponsiveness threshold, because it inhibits the mediators released by the various cells, and reduces the involvement and activation of inflammatory cells. The aim of this study was to evaluate the state of activation of the immunocompetent cells and the main chemical mediators present in the bronchoalveolar lavage (BAL) fluid from 10 atopic asthmatic patients, before and after treatment with nedocromil sodium. The following examinations were performed before treatment and after 120 days of therapy with nedocromil sodium at 16 mg/day (two 2-mg puffs x 4): the level of chemical mediators and the state of activation of immunocompetent cells in BAL fluid; immunological analytes in activation of immunocompetent cells in BAL fluid; immunological analytes in peripheral blood; aspecific bronchial challenge test with ultrasonicated bidistilled H2O fog to evaluate variations in the hyperreactivity threshold; questionnaire to determine any adverse effects of treatment (cough, breathlessness, sleep disorders). Our findings demonstrate that nedocromil sodium prevents the release of chemotactic and inflammatory mediators by the effector cells and thus stabilizes microvascular permeability and epithelial damage, so raising the threshold of response to bronchoconstriction stimuli. Lastly, nedocromil sodium is associated with a better preventive therapeutic efficacy and good tolerance and can therefore be suggested as a valid drug to be used in the long-term treatment of bronchial asthma.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Albumins; Asthma; Blood Proteins; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Dinoprostone; Eosinophil Granule Proteins; Humans; Hypersensitivity; Immunoglobulins; Immunologic Factors; Leukocytes; Leukotriene B4; Lymphocytes; Macrophages; Male; Nedocromil; Peptide Hydrolases; Ribonucleases; Thromboxane B2

Topics: Administration, Inhalation; Animals; Antibodies, Monoclonal; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Chemotaxis, Leukocyte; Eosinophils; Guinea Pigs; Immunization; Interleukin-5; Leukotriene B4; Male; Ovalbumin; Platelet Activating Factor

1. The effect of a single intratracheal dose (10 mg) of PF 5901 (2-[3(1-hydroxyhexyl) phenoxymethyl] quinoline hydrochloride, a specific inhibitor of the 5-lipoxygenase pathway of arachidonic acid metabolism and a leukotriene D4 antagonist) on airway changes induced in response to Alternaria tenuis aerosol challenge was assessed in adult rabbits neonatally immunized. Leukotriene generation was determined in vivo by measuring leukotriene B4 (LTB4) levels in bronchoalveolar lavage (BAL) fluid and ex vivo by measuring calcium ionophore-stimulated production of LTB4 in whole blood. 2. While PF 5901 (10 mg) had no significant effect on the acute bronchoconstriction induced by antigen, this dose was sufficient to inhibit significantly the increase in airway responsiveness to inhaled histamine 24 h following antigen challenge (P < 0.05). 3. Total leucocyte infiltration into the airways induced by antigen, as assessed by bronchoalveolar lavage, was significantly inhibited by pretreatment with PF 5901 (10 mg). However, the pulmonary infiltration of neutrophils and eosinophils induced by antigen was unaltered by prior treatment with PF 5901 (10 mg). 4. PF 5901 (10 mg) had no effect on ex vivo LTB4 synthesis in whole blood. However, the antigen-induced increase in LTB4 levels in BAL 24 h following challenge was significantly inhibited (P < 0.05). 5. We suggest from the results of the present study that the antigen-induced airway hyperresponsiveness to inhaled histamine in immunized rabbits is mediated, at least in part, by products of the 5-lipoxygenase metabolic pathway, and is not dependent on the extent of eosinophil or neutrophil influx into the airway lumen.

Topics: Administration, Inhalation; Airway Resistance; Alternaria; Animals; Animals, Newborn; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Bronchoconstriction; Female; Histamine; Leukotriene B4; Leukotriene D4; Lipoxygenase Inhibitors; Lung; Lung Compliance; Male; Quinolines; Rabbits; Respiratory Function Tests; Respiratory Hypersensitivity

We used the 5-lipoxygenase-activating protein (FLAP) antagonist MK-0591 to investigate the importance of leukotrienes (LT) in causing ozone-induced bronchoconstriction, airway inflammation, and airway hyperresponsiveness in dogs. Six random source dogs were studied. On one day, dogs were treated with MK-0591 (2 mg/kg iv) followed by a continuous intravenous infusion of 8 micrograms.kg-1.min-1. On the other day, the diluent was infused. Acetylcholine airway responsiveness was measured before and 1 h after ozone inhalation (3 ppm for 30 min). On each day, whole blood and bronchoalveolar lavage (BAL) cells were challenged with calcium ionophore to stimulate LTB4 production. Urinary LTE4 levels were measured before and after ozone. MK-0591 inhibited LTB4 production in whole blood by 96% (P = 0.001) and that from BAL cells by 91% (P = 0.001). By contrast, MK-0591 had no effect on ozone-induced bronchoconstriction, airway hyperresponsiveness, or influx of neutrophils into BAL. The mean log difference of the pre- to post-acetylcholine provocative concentration was 0.64 +/- 0.40 during MK-0591 treatment and 0.68 +/- 0.40 during diluent treatment (P = 0.71). These results indicate that peptidoleukotrienes are produced during ozone inhalation and that MK-0591 inhibits LT production in dogs. However, LTs do not play a role in ozone-induced bronchoconstriction, airway inflammation, or airway hyperresponsiveness in dogs.

Topics: 5-Lipoxygenase-Activating Proteins; Acetylcholine; Airway Resistance; Animals; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Carrier Proteins; Dogs; Indoles; Inflammation; Leukotriene Antagonists; Leukotriene B4; Leukotriene E4; Leukotrienes; Lipoxygenase Inhibitors; Membrane Proteins; Ozone; Quinolines; Respiratory System

Ovalbumin inhalation by sensitized guinea pigs induced a marked increase in the number of eosinophils (0.89 +/- 0.18 to 5.45 +/- 0.77 x 10(5)/ml, n = 10, p < 0.05) and elevations in the amounts of protein and eosinophil-derived major basic protein (MBP) (1,010.7 +/- 184.9 to 4,116.6 +/- 973.0 ng/ml, n = 10, p < 0.05) recovered by bronchoalveolar lavage (BAL). In contrast, no changes in the levels of eosinophil peroxidase (EPO) or in the sensitivity of the airways to bronchoconstriction induced by methacholine were detected. However, when ovalbumin-exposed guinea pigs received an intratracheal instillation of 1 microgram leukotriene (LT)B4 30 min prior to methacholine provocation, elevated levels of EPO and MBP in the BAL fluid and a marked bronchial hyperreactivity to methacholine were noted when compared with saline-challenged LTB4-injected animals (p < 0.05). In contrast, the intratracheal instillation of 1 or 3 micrograms platelet-activating factor (PAF) did not significantly modify the bronchial reactivity to methacholine or the levels of EPO and MBP. PAF and LTB4 induced similar enhancements in the amount of protein in BAL fluids from antigen-exposed guinea pigs, suggesting that increased endothelial/epithelial permeability does not account for hyperreactivity. A significant correlation between the levels of EPO or MBP and the intensity of the bronchial responsiveness to methacholine were shown in ovalbumin-challenged guinea pigs, irrespective of their subsequent treatment, i.e., either with PAF or with LTB4 or with their vehicle (r = 0.579, p = 0.0002 and r = 0.330, p = 0.049, n = 36 for EPO and MBP, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Blood Proteins; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Bronchoconstriction; Eosinophil Granule Proteins; Eosinophil Peroxidase; Eosinophils; Guinea Pigs; Leukotriene B4; Male; Methacholine Chloride; Ovalbumin; Peroxidases; Platelet Activating Factor; Proteins; Respiratory Hypersensitivity; Ribonucleases

Effects of R[+]-8-([1-[3,4-dimethoxyphenyl]-2-hydroxyethyl]amino) -3,7-dihydro-7-[2-methoxyethyl]-1,3-dimethyl-1H-purine-2,6-dione (MKS-492), a reported type III isozyme inhibitor of cyclic nucleotide phosphodiesterase, on antigen- or platelet activating factor (PAF)-induced bronchoconstriction and allergic reactions in guinea pigs and rats were investigated. 1) MKS-492 inhibited antigen-induced bronchoconstriction in guinea pigs. Aminophylline also inhibited the reaction. 2) MKS-492 inhibited PAF-induced bronchoconstriction and inhibited the increase in airway responsiveness to histamine in guinea pigs, although aminophylline failed to affect these reactions. 3) MKS-492 relaxed guinea pig tracheal muscle in vitro more potently than aminophylline. 4) MKS-492 inhibited leukotriene B4 (LTB4)-induced airway eosinophilia in guinea pigs. 5) MKS-492 inhibited passive cutaneous anaphylaxis and mediator-induced skin reactions in rats more potently than aminophylline. Both drugs inhibited antigen- and phospholipase A2-induced histamine release from guinea pig lung tissue. 6) MKS-492 inhibited PAF-induced O2- generation from guinea pig alveolar macrophages. These results indicate that MKS-492 is a more potent inhibitor of allergic bronchoconstriction and PAF- or LTB4-induced inflammatory reactions in guinea pigs and the allergic cutaneous reactions in rats when compared to aminophylline.

Topics: Aminophylline; Animals; Antigens; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Bronchoconstriction; Female; Guinea Pigs; Histamine; Histamine Release; Hypersensitivity; Leukocyte Count; Leukotriene B4; Male; Muscle Relaxation; Muscle, Smooth; Passive Cutaneous Anaphylaxis; Phosphodiesterase Inhibitors; Platelet Activating Factor; Purinones; Rats; Rats, Wistar; Superoxides; Trachea

In this study, it was presented that PAF and LTB4 exert a priming effect on PMNs to promote their superoxide anion production. PMNs preincubated with PAF of normal controls or PMNs from asthmatic patients are activated and their responsiveness to inhibitory stimuli such as antiallergic drugs and corticosteroid are attenuated. In conclusions, inflammatory cells of asthmatics may be activated by various mediators and play an important role in the progress of airway damage.

Topics: Adult; Aged; Asthma; Bronchial Hyperreactivity; Cells, Cultured; Dexamethasone; Female; Humans; Leukotriene B4; Lymphocyte Activation; Macrophage Activation; Macrophages, Alveolar; Male; Middle Aged; Neutrophils; Phthalazines; Platelet Activating Factor; Superoxides

Although it has been postulated that inflammatory cells cause the bronchial hyperresponsiveness which is diagnostic of asthma, until recently there has been little direct evidence of such a link. We have recently shown that calcium ionophore-activated human neutrophils and eosinophils can induce a state of human airway hyperresponsiveness in vitro. In this study we have shown that the anti-inflammatory agent nedocromil sodium, 10(-7) M, inhibited the hyperresponsiveness induced by products released from ionophore activated neutrophils but did not inhibit the release of leukotriene B4 from the same cells. Neutrophil-induced bronchial hyperresponsiveness was also inhibited by pre-treatment of the bronchial tissues with a thromboxane A2 and prostaglandin receptor antagonist, GR32191, 10(-7) M. These findings indicate that cyclooxygenase products are involved in bronchial hyperresponsiveness induced by inflammatory cell products in vitro and that their release can be inhibited by nedocromil sodium.

Topics: Biphenyl Compounds; Bronchi; Bronchial Hyperreactivity; Calcimycin; Granulocyte-Macrophage Colony-Stimulating Factor; Heptanoic Acids; Histamine; Humans; Leukotriene B4; N-Formylmethionine Leucyl-Phenylalanine; Nedocromil; Neutrophils; Quinolones; Receptors, Thromboxane

The involvement of platelet activating factor (PAF) in antigen-induced bronchial hyperresponsiveness was investigated by the use of the PAF antagonists BN 52021 and BN 50730, in a guinea-pig model where sensitization and challenge were performed by aerosol. Male Hartley guinea-pigs were sensitized by two aerosol exposures at 48 hr intervals to a 0.9% NaCl solution (saline) containing 2 mg/ml ovalbumin for 30 min. Fifteen to 20 days later, guinea-pigs were challenged by exposure to five successive aerosols of increasing concentrations of ovalbumin (OA) or respectively, 10 microg/ml, 100 microg/ml, 1 mg/ml, 5 mg/ml and 10 mg/ml for 15 min each, or saline alone. Three to four hr and 18-24 hr after the aerosol challenge the guinea-pigs were prepared for recording of bronchopulmonary response and aerosol administrations were then generated with an ultrasonic nebulizer. The bronchopulmonary responses induced by successive 1-min aerosol bursts of acetylcholine (ACh) was assessed. As compared with saline-challenged guinea-pigs, an enhanced bronchopulmonary response to aerosol administration of cumulative doses of ACh was observed, 3-4 hr and 18-24 hr post-ovalbumin challenge. When the sensitized guinea-pigs were pretreated 1 hr before ovalbumin exposure with BN 52021 or BN 50730 (25 mg/kg, per os), a significant inhibition of the increase in the bronchopulmonary response to ACh was observed, both at 3-4 hr and 18-24 hr. Furthermore, when guinea-pigs were treated 3-4 hr after the ovalbumin exposure with BN 52021 or BN 50730, a significant inhibition of the hyperresponsiveness to ACh was recorded at 18-24 hr. A marked accumulation of eosinophils in the peribronchial regions was observed on histological preparations of lung specimens collected 4 hr or 24 hr after ovalbumin exposure. Pretreatment of the guinea-pigs by BN 50730 or BN 52021 did not modify the eosinophil accumulation in the peribronchial area. No significant difference in the number of eosinophils collected in the bronchoalveolar lavage fluid is observed, 24 hr post-ovalbumin challenge, under the pretreatment with BN 52021 or BN 50730. Pretreatment of guinea-pigs by BN 50730 or BN 52021 significantly reduced the PAF-induced (100 microg/ml) increase in eosinophil number in the peribronchial area. By contrast, they did not inhibit the eosinophilia induced by aerosol administration of LTB4 (5 microg/ml). These results suggest that the bronchial hyperresponsiveness observed in this study is associated with

Topics: Acetylcholine; Aerosols; Animals; Azepines; Bronchial Hyperreactivity; Bronchial Provocation Tests; Bronchoalveolar Lavage Fluid; Bronchoconstrictor Agents; Diterpenes; Eosinophilia; Ginkgo biloba; Ginkgolides; Guinea Pigs; Lactones; Leukotriene B4; Lung Diseases; Male; Molecular Structure; Ovalbumin; Plants, Medicinal; Platelet Activating Factor; Specific Pathogen-Free Organisms; Thienopyridines; Triazoles

To investigate the relative irritant potencies of inhaled aldehydes, guinea pigs were exposed to formaldehyde or acrolein and specific total pulmonary resistance and bronchial reactivity to intravenous acetylcholine were assessed. The mechanisms associated with these responses were investigated by analyzing morphologic and biochemical changes in airway epithelial cells after in vivo and in vitro exposures. Immediately after exposure to formaldehyde or acrolein, specific resistance increased transiently and returned to control values within 30 to 60 minutes. Bronchial hyperreactivity, assessed by the acetylcholine dose necessary to double resistance, increased and became maximal two to six hours after exposure to at least 9 parts per million2 (ppm) formaldehyde or at least 1 ppm acrolein for two hours. The effect of exposure to 3 ppm formaldehyde for two hours was less than the effect of exposure to 1 ppm formaldehyde for eight hours; thus, extended exposures produced a disproportionate heightening of bronchial reactivity. Bronchial hyperreactivity often persisted for longer than 24 hours. Increases in three bronchoconstrictive eicosanoids, prostaglandin F2 alpha, thromboxane B2, and leukotriene C4, occurred immediately after exposure, whereas an influx of neutrophils into lavage fluid occurred 24 hours later. Histological examination of the tracheal epithelium and lamina propria also demonstrated a lack of inflammatory cell infiltration. Treatment with leukotriene synthesis inhibitors and receptor antagonists inhibited acrolein-induced hyperreactivity, supporting a causal role for these compounds in this response. Acrolein also stimulated eicosanoid release from bovine epithelial cells in culture. However, the profile of metabolites formed differed from that found in lavage fluid after in vivo exposure. Similarly, human airway epithelial cells did not produce cysteinyl leukotriene or thromboxane B2. However, cysteinyl leukotrienes were mitogenic for human airway epithelial cells in a concentration-dependent manner and exhibited a structure-activity relationship; leukotriene C4 was more potent than its sequential metabolites D4 and E4. The potency of leukotriene C4 was striking, stimulating colony-forming efficiency in concentrations as low as 0.01 pM. Together, these findings suggest that environmentally relevant concentrations of aldehydes can induce bronchial hyperreactivity in guinea pigs through a mechanism involving injury to cells present in the air

Topics: Acetylcholine; Acrolein; Air Pollutants; Airway Resistance; Animals; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Epithelium; Epoprostenol; Formaldehyde; Guinea Pigs; Hyperplasia; Inflammation; Leukocyte Count; Leukotriene B4; Lipoxygenase Inhibitors; Neutrophils; Phenothiazines; Phenylbutyrates; Prostaglandins F; SRS-A; Thromboxane B2; Time Factors

In order to investigate the possible contribution of leukotrienes to the airway hypersensitiveness and inducibility of asthmatic spells, the probable temporal correlation of the urinary leukotriene levels (U-LTB4 and U-LTC4) were estimated along with the peripheral neutrophil counts in two groups of asthmatic children with or without an inflammatory sign of the elevated CRP. The first group consisted of 6 asthmatic children possessing inflammatory signs and symptoms of fever and peripheral leukocytosis. They all were hospitalized. The second group of 6 patients of light asthmatic attack without any signs and symptoms of acute inflammation were studied in the Outpatient Department. In the first group, U-LTB4 was as high as 258.6 +/- 88.9 ng/mmol Cr. during the attacks while U-LTB4 levels of the second group was as low as 62.2 +/- 32.20 ng/mmol Cr. The difference was statistically significant at p less than 0.01. Further mathematical analysis revealed a positive correlation of U-LTB4 to the peripheral neutrophils counts at r = 0.71. Thus, it was concluded that the elevation of U-LTB4 levels in the first group was strongly related to infections, and their asthmatic spells were thought to represent an infection-induced type. On the contrary, U-LTC4 levels in the samples during the asthmatic attacks were increased in 2 of the 6 of the first group. They both represented grave asthmatic spells. In the remainder, U-LTC4 levels did not rise enough to induce spasmodic contractions of the bronchial smooth muscles. Thus, it was also discussed that the most appropriate timing for urine collection for the study of U-LTs is some time following an asthmatic attack.

Topics: Age Factors; Asthma; Bronchial Hyperreactivity; Child; Child, Preschool; Female; Humans; Infant; Leukocyte Count; Leukotriene B4; Male; Neutrophils; SRS-A

Leukotrienes are thought to be involved in allergen-induced airway responses. To test this hypothesis we used a newly described 5-lipoxygenase inhibitor, zileuton, and examined its effect on antigen-induced early and late bronchial responses, airway inflammation and airway hyperresponsiveness in allergic sheep. Early and late responses were determined by measuring specific lung resistance (SRL) before and serially for 8 h after antigen challenge. Airway inflammation was assessed by bronchoalveolar lavage performed before, 8 h after and 24 h after antigen challenge. Airway responsiveness was measured before and 24 h after challenge by determining the dose of inhaled carbachol that caused a 400% increase in SRL (PD400%). The sheep (n = 8) were challenged with Ascaris suum antigen once after vehicle treatment (methylcellulose) and once after treatment with zileuton (10 mg/kg in methylcellulose, p.o.) given 2 h before antigen challenge. Trials were separated by at least 21 days. Zileuton had no effect on the early bronchoconstrictor response to antigen but the drug inhibited the late bronchial response by 55% (P less than 0.05). Unlike the control trial, there was no significant increase in bronchoalveolar lavage eosinophils at 8 h post challenge in the zileuton-treated sheep. Furthermore, zileuton treatment blocked (P less than 0.05) the airway hyperresponsiveness seen 24 h after challenge. Ex vivo formation of leukotriene B4 was inhibited over several hours after a single oral dose of zileuton, indicating that the compound was acting as a 5-lipoxygenase inhibitor in vivo. These results suggest that 5-lipoxygenase metabolites contribute to allergen-induced late responses, airway inflammation and airway hyperresponsiveness in this animal model of asthma.

Topics: Administration, Oral; Animals; Antigens; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Bronchoconstriction; Calcimycin; Dose-Response Relationship, Drug; Hydroxyurea; Leukotriene B4; Lipoxygenase Inhibitors; Sheep

To study the role of chemical mediators in airway hyperresponsiveness and simultaneous eosinophilia, we examined effects of a potent 5-lipoxygenase inhibitor FR110302 and those of prednisolone, indomethacin, platelet-activating factor (PAF) antagonist (RP-59227) and leukotriene C4 (LTC4) antagonist (ONO-1078) on airway hyperresponsiveness and lung eosinophilia induced by Sephadex particles. Sephadex G200 particles (2.5 mg/kg) were injected intravenously to rats and 3 days later the airway hyperresponsiveness to acetylcholine (ACh) and the eosinophilia in the bronchoalveolar lavage (BAL) fluids were observed. FR110302 (10 mg/kg b.i.d.p.o.) significantly suppressed both of these indicators of asthma. The amounts of immunoreactive LTB4,C4 (i-LTB4, C4) in the BAL fluid were measured by radioimmunoassay. The amounts of i-LTB4,C4 in the FR110302-treated rats were significantly less compared with that in the Sephadex-injected controls. Prednisolone completely inhibited the airway hyperresponsiveness. PAF antagonist and LTC4 antagonist partially inhibited the airway hyperresponsiveness, and indomethacin had no effect. The results indicate that 5-lipoxygenase products play important roles in the Sephadex-induced airway hyperresponsiveness and lung eosinophilia in rats.

Topics: Acetylcholine; Animals; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Chromones; Dextrans; Guinea Pigs; Humans; Ileum; In Vitro Techniques; Indomethacin; Leukotriene B4; Lipoxygenase Inhibitors; Male; Microspheres; Naphthols; Platelet Activating Factor; Prednisolone; Pulmonary Eosinophilia; Pyridines; Quinolines; Rats; Rats, Inbred Strains; SRS-A; Thiazoles