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Background: Atopic asthma is an allergic disease typically associated with T(H)2 cytokines. IL-17A is also associated with asthma, through the induction of chemokines. Mucosal CCL28 concentrations correlate with cellular recruitment to inflamed airways and support migration of IgA(+) B cells. Here, a link between IL-17A, CCL28 and IgE-secreting B cell chemotaxis is examined., Methods: Primary human airway cells and the airway epithelial line A549 were used to characterize IL-17A receptor expression and the effect of IL-17A on CCL28 transcription and translation. B cells, differentiated to IgE+ cells ex vivo, were assessed for CCR10 surface expression and chemotaxis to CCL28 by flow cytometry, transwell migration and ELISpot., Results: Human airway epithelium expressed both IL-17RA and IL-17RC, and was responsive to IL-17A stimulation. Cultured human IgE+ B cells expressed surface CCR10 and displayed CCR10-dependent chemotaxis towards recombinant CCL28. Enhanced levels of CCL28 were observed upon A549 cell incubation with IL-17A, and this up-regulation significantly increased the migration of IgE+ antibody-secreting B cells. The specificity of chemotaxis was confirmed by migration blockade in the presence of anti-CCL28 or anti-CCR10., Conclusions: This work identifies a novel chemokine for the migration of IgE+ B cells, in addition to characterizing induction of CCL28 by IL-17A. Taken together the results presented here propose a new role for IL-17A in the allergic airways, linking this cytokine with the recruitment of IgE+ antibody-secreting B cells, via the induction of CCL28. These observations justify further in vivo studies of larger cohorts., (Copyright © 2011 S. Karger AG, Basel.)

Background: Secondary to the phase-out of chlorofluorocarbons (CFCs), the albuterol (Ventolin, GlaxoSmithKline, Uxbridge, Middlesex, United Kingdom) pressurized metered-dose inhaler (MDI) has been formulated in a non-ozone-depleting propellant, hydrofluoroalkane (HFA) 134a., Objective: To compare the efficacy of albuterol HFA to albuterol CFC and placebo HFA in protecting patients from exercise-induced bronchospasm (EIB)., Methods: Randomized, double-blind, placebo-controlled, three-way crossover study in patients with documented EIB. Patients (n = 24) aged 18 to 45 years old received albuterol HFA or albuterol CFC, (total dose of 180 microg ex-actuator), or placebo HFA via an MDI, 30 minutes before a standardized exercise challenge. Serial forced expiratory volume in 1 second (FEV1) measurements were made 5 minutes before exercise and 5, 10, 15, 20, 25, 30, and 60 minutes postexercise. The primary outcome measure was the maximum percentage fall in FEV1 over the 60 minutes after exercise., Results: The adjusted mean maximum percentage falls in FEV1 postexercise for albuterol HFA and CFC groups were 15.4% and 14.9%, respectively. The two formulations were comparable with a treatment difference of -0.5% (P = 0.848; 95% confidence interval, -5.3 to 4.4%). When compared with the fall in FEV1 for placebo (33.7%), both active treatments demonstrated a significantly smaller fall in FEV1 postexercise (P < 0.001). Safety profiles were similar among the three treatment groups., Conclusions: The results provide assurance to prescribers that the formulation of albuterol in the non-ozone-depleting propellant HFA 134a has not affected its efficacy in the treatment of EIB in asthmatic patients. Single doses of albuterol HFA and CFC from an MDI are comparable in terms of efficacy and safety on a microgram per microgram basis.

Background: Leukotrienes are lipid mediators generated from arachidonic acid by the 5-lipoxygenase pathway which may play an important part in the pathophysiology of asthma. Previous studies have demonstrated attenuation of the allergen-induced early and late asthmatic responses by leukotriene receptor antagonists. The effect of the 5-lipoxygenase inhibitor ZD2138, a non-redox lipoxygenase inhibitor which inhibits leukotriene synthesis for 24 hours after single doses of 350 mg, on allergen-induced early and late asthmatic responses has been assessed., Methods: Eight asthmatic subjects with baseline FEV1 > 70% were studied. On screening, all subjects developed an allergen-induced biphasic asthmatic response to grass pollen, cat dander, or house dust mite. ZD2138 (350 mg) or placebo was given on two occasions separated by two weeks in a randomised double blind fashion. Allergen inhalation challenge was performed four hours after dosing and FEV1 was measured for eight hours. The inhibitory activity of ZD2138 on the 5-lipoxygenase pathway was assessed by measurements of calcium ionophore-stimulated generation of LTB4 in whole blood ex vivo and by analysis of urinary LTE4 levels before administration of drug or placebo and at regular intervals after oral drug dosing and allergen challenge., Results: ZD2138 produced no significant bronchodilatation or attenuation of the early or late asthmatic response, although there was 82% inhibition of whole blood generation of LTB4 in response to calcium ionophore stimulation and 52% reduction in urinary excretion of LTE4., Conclusions: In asthmatic subjects the 5-lipoxygenase inhibitor ZD2138 did not protect against allergen-induced asthmatic responses, despite substantial inhibition of 5-lipoxygenase.

Placement of an intrabronchial single balloon catheter provides the possibility of measuring histamine release in isolated large airway segments in vivo. We wanted to assess the protective effect of nedocromil sodium on intrabronchial histamine release after hyperosmolar challenge. Six mild asthmatics were bronchoscoped 30 min after inhalation of 4 mg nedocromil sodium or placebo, given via a metered dose inhaler in a randomized, double-blind, cross-over study. Lavage of the left main bronchus was carried out proximal to a balloon catheter inflated at its bifurcation, and specimens were assayed for histamine and prostaglandin D2 (PGD2) by radioimmunoassay. The rise in histamine concentration in bronchial epithelial fluid following hyperosmolar saline challenge was significantly greater following placebo than following nedocromil sodium (mean +/- SEM prechallenge histamine concentration on placebo day 6.9 +/- 2.9 nM; post-challenge: 25.3 +/- 8.0 nM; mean +/- SEM prechallenge histamine concentration on the day nedocromil sodium was given: 3.7 +/- 0.7 nM; post-challenge 5.8 +/- 1.7 nM). Changes in PGD2 levels reflected the changes in histamine, but the variability of response was large, and there were no significant differences between the effects of placebo and nedocromil sodium. The procedure caused significantly greater falls in peak expiratory flow rates following placebo (mean +/- SEM percentage fall 20.2 +/- 4.4%) than following nedocromil sodium (0.9 +/- 5.8%, p < 0.02). We conclude that there is tonic basal histamine release within asthmatic airways, and that nedocromil sodium inhibits histamine release from mediator cells in vivo.

Urinary leukotriene E4 (LTE4) concentrations were measured in six asthmatic subjects after treadmill exercise, and in five asthmatic subjects after allergen challenge. Exercise and allergen challenge produced a 42 +/- 18% (mean +/- SD) and 22 +/- 8% fall in FEV1, respectively. The baseline concentration of urinary LTE4 in subjects challenged with exercise was 64 (27 to 150) pg/mg creatinine (geometric mean and 95% confidence interval), and in those challenged with allergen it was 36 (23 to 59) pg/mg creatinine. Urinary LTE4 concentrations did not change significantly in the 24 h after exercise. In contrast, there was a mean 4-fold increase in urinary LTE4 during the 3 h after allergen challenge.

The effects of prior inhalation of each of the sulfidopeptide leukotrienes (LT), LTC4, LTD4, and LTE4 on airway responsiveness to histamine have been compared in seven asthmatic and six normal subjects. Each subject underwent histamine inhalation challenge at 1, 4, and 7 h after inhalation of phosphate-buffered saline and bronchoconstricting doses of LTC4, LTD4, LTE4, and methacholine, which produced a greater than 30% fall in specific airway conductance. In asthmatic subjects, prior inhalation of LTC4, LTD4, and LTE4 enhanced airway responsiveness to histamine when compared with saline inhalation, on average by a maximum of 3.9-, 2.8-, and 3.1-fold, respectively, at 4 h after inhalation. Methacholine inhalation did not significantly after histamine responsiveness throughout the time course studied. In normal subjects, inhalation of LTC4, LTD4, LTE4, and methacholine did not change airway responsiveness to histamine. Thus, LTC4 and LTD4 were similar to LTE4 in their capacity to enhance airway responsiveness to histamine in asthmatic subjects, and, in common with LTE4, they failed to elicit a change in airway responsiveness to histamine in normal subjects.

Bronchial asthma is characterized by airways inflammation and airways hyperresponsiveness. It is unlikely that the pathophysiology of asthma and bronchial hyperresponsiveness can be explained on the basis of a single cell or a single class of mediators. Nevertheless, the possibility that leukotrienes may contribute to the pathogenesis of the inflammatory, vasoactive ans spasmogenic components of bronchial asthma is suggested by the properties of these lipid mediators, the preferential capacity of inflammatory cells to generate leukotrienes and the presence of leukotrienes in the airways of asthmatic subjects. The sulphidopeptide leukotrienes are potent bronchoconstrictor agonists when inhaled. The airways of asthmatic subjects are hyperresponsive to leukotrienes as to other bronchoconstrictor agonists. Nevertheless, the airways responsiveness of asthmatic subjects to these agonists demonstrate several unusual properties. While the airways of asthmatic subjects are relatively less responsive to LTC4 and LTD4, compared to agents such as histamine or methacholine, they demonstrate a marked and selective hyperresponsiveness to LTE4, suggesting a possibly unique role for this mediator in the pathogenesis of airways hyperresponsiveness. In addition an increased sensitivity of the airways to LTE4 may contribute to the mechanism of aspirin-induced asthma. The capacity of the sulphidopeptide leukotrienes to increase the airways responsiveness of normal subjects to methacholine and of asthmatic subjects to histamine is further evidence for a role for these substances in the pathogenesis of bronchial asthma.

Airways responsiveness to leukotriene (LT) C4, LTD4, LTE4, histamine, and methacholine have been studied in eight asthmatic and six normal subjects. Airways responsiveness to each bronchoconstrictor agonist was assessed by constructing cumulative dose-response curves, and the dose that produced a 35% decrease in specific airways conductance (PD35) was obtained by linear interpolation. Airways of subjects with asthma were approximately 14-, 15-, 6-, 9-, and 219-fold more responsive to histamine, methacholine, LTC4, LTD4, and LTE4, respectively, than were normal subjects. Thus, there was a substantially augmented level of hyperresponsiveness to LTE4 in bronchial asthma, which was not observed for the other bronchoconstrictor agents, when compared to normal subjects. In contrast to LTC4 and LTD4, as histamine and methacholine responsiveness increase, the dose ratio of histamine to LTE4 (PD35 histamine/PD35 LTE4) and the dose ratio of methacholine to LTE4 also tended to increase. This suggests that as the nonspecific airways responsiveness increases, the relative potency of LTE4 also increases, whereas potency of LTC4 and LTD4 decrease. These results suggest that the mechanism of the bronchoconstriction induced by LTE4 may be distinct from that produced by LTC4 or LTD4 in subjects with asthma. This may reflect leukotriene subtype receptor heterogeneity in asthmatic airways.