The effect of montelukast (MK-0476), a cysteinyl leukotriene receptor antagonist, on allergen-induced airway responses and sputum cell counts in asthma

Current perspective on eicosanoids in asthma and allergic diseases: EAACI Task Force consensus report, part I

Eicosanoids are biologically active lipid mediators, comprising prostaglandins, leukotrienes, thromboxanes, and lipoxins, involved in several pathophysiological processes relevant to asthma, allergies, and allied diseases. Prostaglandins and leukotrienes are the most studied eicosanoids and established inducers of airway pathophysiology including bronchoconstriction and airway inflammation. Drugs inhibiting the synthesis of lipid mediators or their effects, such as leukotriene synthesis inhibitors, leukotriene receptors antagonists, and more recently prostaglandin D₂ receptor antagonists, have been shown to modulate features of asthma and allergic diseases. This review, produced by an European Academy of Allergy and Clinical Immunology (EAACI) task force, highlights our current understanding of eicosanoid biology and its role in mediating human pathology, with a focus on new findings relevant for clinical practice, development of novel therapeutics, and future research opportunities.

Allergen bronchoprovocation test: an important research tool supporting precision medicine

PURPOSE OF REVIEW

Allergen bronchoprovocation test (ABT) has been used to study asthma pathophysiology and as a disease-modelling tool to assess the properties and efficacy of new asthma drugs. In view of the complexity and heterogeneity of asthma, which has driven the definition of several phenotypes and endotypes, we aim to discuss the role of ABT in the era of precision medicine and provide guidance for clinicians how to interpret and use available data to understand the implications for the benefits of asthma treatment.

RECENT FINDINGS

In this review, we summarize background knowledge and applications of ABT and provide an update with recent publications on this topic. In the past years, several studies have been published on ABT in combination with non-invasive and invasive airway samplings and innovative detection techniques allowing to study several inflammatory mechanisms linked to Th2-pathway and allergen-induced pathophysiology throughout the airways.

SUMMARY

ABT is a valuable research tool, which has strongly contributed to precision medicine by helping to define allergen-triggered key inflammatory pathways and airway pathophysiology, and thus helped to shape our understanding of allergen-driven asthma phenotypes and endotypes. In addition, ABT has been instrumental to assess the interactions and effects of new-targeted asthma treatments along these pathways.

Dysregulated metabolism of polyunsaturated fatty acids in eosinophilic allergic diseases

Polyunsaturated fatty acids (PUFAs), represented by the omega-6 fatty acid arachidonic acid (AA) and omega-3 fatty acid docosahexaenoic acid (DHA), are essential components of the human body. PUFAs are converted enzymatically into bioactive lipid mediators, including AA-derived cysteinyl leukotrienes (cys-LTs) and lipoxins and DHA-derived protectins, which orchestrate a wide range of immunological responses. For instance, eosinophils possess the biosynthetic capacity of various lipid mediators through multiple enzymes, including 5-lipoxygenase and 15-lipoxygenase, and play central roles in the regulation of allergic diseases. Dysregulated metabolism of PUFAs is reported, especially in severe asthma, aspirin-exacerbated respiratory disease, and eosinophilic chronic rhinosinusitis (ECRS), which is characterized by the overproduction of cys-LTs and impaired synthesis of pro-resolving mediators. Recently, by performing a multi-omics analysis (lipidomics, proteomics, and transcriptomics), we demonstrated the metabolic derangement of eosinophils in inflamed tissues of patients with ECRS. This abnormality occurred subsequent to altered enzyme expression of gamma-glutamyl transferase-5. In this review, we summarize the previous findings of dysregulated PUFA metabolism in allergic diseases, and discuss future prospective therapeutic strategies for correcting this imbalance.

The effect of allergen-induced bronchoconstriction on concentration of 5-oxo-ETE in exhaled breath condensate of house dust mite-allergic patients

BACKGROUND

Arachidonic acid metabolites regulate several aspects of airway function including inflammation, muscle contraction and mucous secretion.

OBJECTIVE

The aim of this study was to evaluate concentration of selected 5-lipoxygenase- and cyclooxygenase-derived eicosanoids in exhaled breath condensate (EBC) during allergen-induced bronchoconstriction.

METHODS

The study was performed on 24 allergic rhinitis/asthma patients sensitized to a house dust mite (HDM) Dermatophagoides pteronyssinus (Dp) and 13 healthy controls (HCs). Bronchial challenge with Dp extract was performed only in the allergic patients. EBC samples were collected before (T₀ ) and during Dp-induced bronchoconstriction (T_EAR ). Eicosanoid concentration was measured using HPLC-tandem mass spectrometry.

RESULTS

Significant bronchoconstriction after Dp challenge was demonstrated in 15 patients (Rs), while in 9 patients (NRs) no asthmatic response could be detected. At T₀ the most abundant eicosanoids in EBC of HDM-allergic patients were LTB₄ and 5-oxo-ETE, while in HCs EBC concentration of LTB₄ was significantly greater than that of 5-oxo-ETE. Allergen challenge resulted in significant increase in EBC concentration of 5-oxo-ETE, LTD₄ and 8-iso-PGE₂ only in Rs. At T_EAR , the relative change of 5-oxo-ETE concentration in EBC correlated with decrease of peripheral blood eosinophilia (R = -0.774; P = .0012). Moreover, the relative increase of 5-oxo-ETE in EBC at T_EAR significantly correlated with the severity of the subsequent late asthmatic response (R = 0.683, P = .007).

CONCLUSION

Our study demonstrates significant up-regulation of 5-oxo-ETE synthesis in HDM-allergic patients and indicates possible involvement of that mediator in the pathogenesis of allergic asthma.

Regulation of Eosinophil and Group 2 Innate Lymphoid Cell Trafficking in Asthma

Asthma is an inflammatory disease usually characterized by increased Type 2 cytokines and by an infiltration of eosinophils to the airways. While the production of Type 2 cytokines has been associated with T_H2 lymphocytes, increasing evidence indicates that group 2 innate lymphoid cells (ILC2) play an important role in the production of the Type 2 cytokines interleukin (IL)-5 and IL-13, which likely amplifies the recruitment of eosinophils from the blood to the airways. In that regard, recent asthma treatments have been focusing on blocking Type 2 cytokines, notably IL-4, IL-5, and IL-13. These treatments mainly result in decreased blood or sputum eosinophil counts as well as decreased asthma symptoms. This supports that therapies blocking eosinophil recruitment and activation are valuable tools in the management of asthma and its severity. Herein, we review the mechanisms involved in eosinophil and ILC2 recruitment to the airways, with an emphasis on eotaxins, other chemokines as well as their receptors. We also discuss the involvement of other chemoattractants, notably the bioactive lipids 5-oxo-eicosatetraenoic acid, prostaglandin D₂, and 2-arachidonoyl-glycerol. Given that eosinophil biology differs between human and mice, we also highlight and discuss their responsiveness toward the different eosinophil chemoattractants.

A dual CysLT1/2 antagonist attenuates allergen-induced airway responses in subjects with mild allergic asthma

BACKGROUND

The cysteinyl leukotrienes (cysLTs) play a key role in the pathophysiology of asthma. In addition to functioning as potent bronchoconstrictors, cysLTs contribute to airway inflammation through eosinophil and neutrophil chemotaxis, plasma exudation, and mucus secretion. We tested the activity of the dual cysLT_1/2 antagonist, ONO-6950, against allergen-induced airway responses.

METHODS

Subjects with documented allergen-induced early (EAR) and late asthmatic response (LAR) were randomized in a three-way crossover study to receive ONO-6950 (200 mg) or montelukast (10 mg) or placebo q.d. on days 1-8 of the three treatment periods. Allergen was inhaled on day 7 two hours postdose, and forced expiratory volume in 1 s (FEV₁ ) was measured for 7 h following challenge. Sputum eosinophils and airway hyperresponsiveness were measured before and after allergen challenge. The primary outcome was the effect of ONO-6950 vs placebo on the EAR and LAR.

RESULTS

Twenty-five nonsmoking subjects with mild allergic asthma were enrolled and 20 subjects completed all three treatment periods per protocol. ONO-6950 was well tolerated. Compared to placebo, ONO-6950 significantly attenuated the maximum % fall in FEV₁ and area under the %FEV₁ /time curve during the EAR and LAR asthmatic responses (P < 0.05) and allergen-induced sputum eosinophils. There were no significant differences between ONO-6950 and montelukast.

CONCLUSIONS

Attenuation of EAR, LAR, and airway inflammation is consistent with cysLT₁ blockade. Whether dual cysLT_1/2 antagonism offers additional benefit for treatment of asthma requires further study.

Allergen-induced airway responses

Environmental allergens are an important cause of asthma and can contribute to loss of asthma control and exacerbations. Allergen inhalation challenge has been a useful clinical model to examine the mechanisms of allergen-induced airway responses and inflammation. Allergen bronchoconstrictor responses are the early response, which reaches a maximum within 30 min and resolves by 1-3 h, and late responses, when bronchoconstriction recurs after 3-4 h and reaches a maximum over 6-12 h. Late responses are followed by an increase in airway hyperresponsiveness. These responses occur when IgE on mast cells is cross-linked by an allergen, causing degranulation and the release of histamine, neutral proteases and chemotactic factors, and the production of newly formed mediators, such as cysteinyl leukotrienes and prostaglandin D2. Allergen-induced airway inflammation consists of an increase in airway eosinophils, basophils and, less consistently, neutrophils. These responses are mediated by the trafficking and activation of myeloid dendritic cells into the airways, probably as a result of the release of epithelial cell-derived thymic stromal lymphopoietin, and the release of pro-inflammatory cytokines from type 2 helper T-cells. Allergen inhalation challenge has also been a widely used model to study potential new therapies for asthma and has an excellent negative predictive value for this purpose.

Effects of JNJ-40929837, a leukotriene A4 hydrolase inhibitor, in a bronchial allergen challenge model of asthma

Leukotriene B4 (LTB4) is a chemotactic mediator implicated in the pathogenesis of asthma. JNJ-40929837 is an oral inhibitor of LTA4 hydrolase, which catalyzes LTB4 production. We evaluated the effects of JNJ-40929837 in a human bronchial allergen challenge (BAC) model. In this double-blind, 3-period crossover study, 22 patients with mild, atopic asthma were randomized to one of three treatments per period: 100 mg/day JNJ-40929837 for 6 days followed by 50 mg/day on day 7; 10 mg/day montelukast for 6 days; and matched placebo. The BAC was performed on day 6 of each treatment period. Primary outcome was BAC-induced late asthmatic response (LAR) measured by maximal percent reduction in forced expiratory volume (FEV1) in one second. Secondary outcomes included early asthmatic response (EAR) by maximal percent reduction in FEV1, EAR and LAR evaluated by area under the FEV1/time curve (AUC0-2, AUC3-10, respectively), change in baseline FEV1 after 5-day treatment, safety, and correlation of JNJ-40929837 to the divalent cation ionophore A23187-stimulated whole blood LTB4 levels and sputum basal LTB4 levels. No significant differences were observed in the primary or secondary FEV1 endpoints with JNJ-40929837 versus placebo. Compared with placebo (n = 17, LS mean = 27.7), there was no significant attenuation of the maximal percent reduction in the LAR FEV1 with JNJ-40929837 (n = 16, LS mean = 28.6, P = 0.63) but montelukast (n = 17, LS mean = 22.6, P = 0.01) significantly attenuated the LAR. JNJ-40929837 substantially inhibited LTB4 production in whole blood, decreased sputum LTB4 levels and was well-tolerated. The number of adverse events leading to study withdrawal was the same in JNJ-40929837 and placebo groups. In conclusion, JNJ-40929837 demonstrated target engagement in blood and sputum. No significant impact in response to allergen inhalation was observed with JNJ-40929837 versus placebo.

REGISTRATION

This study is registered at ClinicalTrials.gov: NCT01241422.

Inhibition of spleen tyrosine kinase attenuates allergen-mediated airway constriction

Spleen tyrosine kinase (SYK) is a key activator of signaling pathways downstream of multiple surface receptors implicated in asthma. SYK function has been extensively studied in mast cells downstream of the high-affinity IgE receptor, FcεR1. Preclinical studies have demonstrated a role for SYK in models of allergic inflammation, but a role in airway constriction has not been demonstrated. Here, we have used a potent and selective pharmacological inhibitor of SYK to determine the role of SYK in allergen-mediated inflammation and airway constriction in preclinical models. Attenuation of allergic airway responses was evaluated in a rat passive anaphylaxis model and rat and sheep inhaled allergen challenge models, as well as an ex vivo model of allergen-mediated airway constriction in rats and cynomolgus monkeys. Pharmacological inhibition of SYK dose-dependently blocked IgE-mediated tracheal plasma extravasation in rats. In a rat ovalbumin-sensitized airway challenge model, oral dosing with an SYK inhibitor led to a dose-dependent reduction in lung inflammatory cells. Ex vivo analysis of allergen-induced airway constriction in ovalbumin-sensitized brown Norway rats showed a complete attenuation with treatment of a SYK inhibitor, as well as a complete block of allergen-induced serotonin release. Similarly, allergen-mediated airway constriction was attenuated in ex vivo studies from nonhuman primate lungs. Intravenous administration of an SYK inhibitor attenuated both early- and late-phase allergen-induced increases in airway resistance in an Ascaris-sensitive sheep allergen challenge model. These data support a key role for SYK signaling in mediating allergic airway responses.

Inhibition of the early asthmatic response to inhaled allergen by the 5-lipoxygenase activating protein inhibitor GSK2190915: a dose-response study

Background

GSK2190915, a 5-lipoxygenase activating protein inhibitor, inhibits the production of cysteinyl leukotrienes and leukotriene B4 and 5-oxo-6,8,11,14-eicosatetraenoic acid. We have previously reported that GSK2190915 100 mg daily inhibits early and late asthmatic responses to inhaled allergen; the effects of lower doses have not been reported. This study assessed the dose–response effects of GSK2190915 10 mg and 50 mg on the early asthmatic response (EAR) to inhaled allergen.

Methods

Nineteen subjects with mild asthma and an EAR were enrolled in a randomized, double-blind, three-way crossover study of GSK2190915 10 mg, 50 mg, and placebo orally once-daily for 3 days. Allergen challenge was performed 2 hours after the third dose.

Results

Compared with placebo, GSK2190915 10 mg and 50 mg caused significant, dose-dependent attenuation of the minimum forced expiratory volume at 1 second (FEV₁) absolute change from baseline; mean treatment differences were 0.21 L (95% confidence interval [CI] 0.04 L, 0.38 L) and 0.41 L (95% CI 0.24 L, 0.58 L), respectively. GSK2190915 50 mg was more effective than 10 mg; mean difference between treatments was 0.20 L, (95% CI 0.03 L, 0.36 L). Compared with placebo, GSK2190915 50 mg, but not 10 mg, significantly inhibited the weighted mean FEV₁ absolute change from baseline.

Conclusion

GSK2190915 50 mg attenuated the EAR similarly to GSK2190915 100 mg in our previous study, suggesting 50 mg is at the top of the dose–response curve. GSK2190915 10 mg is a suboptimal dose. The EAR can be used to assess the therapeutic dose of a new treatment for asthma.

Inhaled allergen bronchoprovocation tests

The allergen bronchoprovocation test is a long-standing exacerbation model of allergic asthma that can induce several clinical and pathophysiologic features of asthma in sensitized subjects. Standardized allergen challenge is primarily a research tool, and when properly conducted by qualified and experienced investigators, it is safe and highly reproducible. In combination with validated airway sampling and sensitive detection techniques, allergen challenge allows the study of several features of the physiology of mainly TH2 cell-driven asthma in relation to the kinetics of the underlying airway pathology occurring during the allergen-induced late response. Furthermore, given the small within-subject variability in allergen-induced airway responses, allergen challenge offers an adequate disease model for the evaluation of new (targeted) controller therapies for asthma in a limited number of subjects. In proof-of-efficacy studies thus far, allergen challenge showed a fair positive predicted value and an excellent negative predictive value for the actual clinical efficacy of new antiasthma therapies, underscoring its important role in early drug development. In this review we provide recommendations on challenge methods, response measurements, sample size, safety, and harmonization for future applications.

The 5-lipoxygenase-activating protein inhibitor, GSK2190915, attenuates the early and late responses to inhaled allergen in mild asthma

BACKGROUND

GSK2190915, a potent 5-lipoxygenase-activating protein inhibitor, prevents the synthesis of leukotrienes and 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE).

OBJECTIVE

To assess the effect of GSK2190915 on the allergen-induced asthmatic responses.

METHODS

Nineteen eligible male subjects with mild asthma were enrolled in and completed this four-centre, double-blind, two-way crossover study (ClinicalTrials.gov NCT00748306). Subjects took GSK2190915 100 mg and placebo orally once daily for 5 days in randomized order. On Day 1 and 4 they had a methacholine challenge, on Day 3 they had an inhaled allergen challenge, and on Days 4 and 6 they had sputum induction.

RESULTS

GSK2190915 attenuated the early (0-2 h) and late (4-10 h) asthmatic responses to inhaled allergen compared with placebo. There was a statistically significant attenuation of the early asthmatic response (EAR) by GSK2190915; treatment difference of GSK2190915 vs. placebo for the minimum FEV(1) EAR was 0.408 L (0.205, 0.611). There was a statistically significant attenuation of the late asthmatic response (LAR) by GSK2190915; the treatment difference of GSK2190915 vs. placebo for the minimum FEV(1) LAR was 0.229 L (0.041, 0.417). There was a statistically significant attenuation of allergen-induced sputum eosinophil count on Day 4 following GSK2190915: mean treatment difference (95% CI) between GSK2190915 and placebo was -9.95% (-18.15%, -1.77%). Compared with placebo, GSK2190915 100 mg reduced median sputum LTB(4) by > 90% on Days 4 and 6. There was no effect on methacholine PC(20) post allergen. GSK2190915 was generally well tolerated.

CONCLUSION AND CLINICAL RELEVANCE

GSK2190915 shows potential as a treatment for patients with asthma.

Effects of add-on montelukast on airway hyperresponsiveness in patients with well-controlled asthma - a pilot study

Objective

Control of airway inflammation is the cornerstone of asthma management. The aim of the present pilot study was to assess the effects of a leukotriene receptor antagonist (LTRA) added to a basic treatment of inhaled corticosteroids (ICS) and long-acting beta-agonist (LABA) on airway hyperresponsiveness, inflammation, and quality of life in well-controlled patients with asthma.

Research design and methods

Seventeen patients (age 18–65, 11 women) with well-controlled asthma presenting airway hyperresponsiveness to mannitol and methacholine challenge were given add-on montelukast on a stable ICS + LABA for 4 weeks. Quality of life and selected parameters of airway inflammation were measured at baseline and at study end. (ClinicalTrials.gov (NCT01725360)).

Results

Adding montelukast to ICS + LABA resulted in an increase in mean FEV₁ (+4.5%, p = 0.057), cumulated higher dose of mannitol (+32.5%, p = 0.023) and methacholine (+17.2%, 0.237) in the provocation test, lower airway reactivity with mannitol and methacholine (response dose ratio (RDR) –50.0%, p = 0.024 and –44.3%, p = 0.006, respectively), and improved airway sensitivity to mannitol and methacholine (+12.1%, p = 0.590 and +48.0%, p = 0.129 for PD15 and PD20 FEV₁, respectively). Changes in inflammation parameters (blood eosinophil count, serum eosinophil cationic protein, and exhaled nitric oxide) were consistent with these findings. Asthma-related quality of life improved significantly in all domains and overall (from 5.3 at baseline to 6.1 at the final visit, p < 0.001). The main limitation was the absence of a control group.

Conclusion

The consistency of the changes in airway hyperresponsiveness and inflammation as well as in quality of life observed with an add-on therapy with montelukast in well-controlled asthma patients during 4 weeks suggests that residual inflammation may represent an area for further improvement of asthma control to be explored in adequately powered randomized controlled trials.

A leukotriene C4 synthase inhibitor with the backbone of 5-(5-methylene-4-oxo-4,5-dihydrothiazol-2-ylamino) isophthalic acid

The cysteinyl leukotrienes (cys-LTs), leukotriene C4 (LTC4) and its metabolites, LTD4 and LTE4, are proinflammatory lipid mediators in asthma and other inflammatory diseases. They are generated through the 5-lipoxygenase/LTC4 synthase (LTC4S) pathway and act via at least two distinct G protein-coupled receptors. The inhibition of human LTC4S will make a simple way to treat the cys-LT relevant inflammatory diseases. Here, we show that compounds having 5-(5-methylene-4-oxo-4,5-dihydrothiazol-2-ylamino) isophthalic acid moiety suppress LTC4 synthesis, glutathione conjugation to the precursor LTA4, in both an enzyme assay and a whole-cell assay. Hierarchical in silico screenings of 6 million compounds provided 300,000 dataset for docking, and after energy minimization based on the crystal structure of LTC4S, 111 compounds were selected as candidates for a competitive inhibitor to glutathione. One of those compounds showed significant inhibitory activity, and subsequently, its derivative 5-((Z)-5-((E)-2-methyl-3-phenylallylidene)-4-oxo-4,5-dihydrothiazol-2-ylamino) isophthalic acid (compound 1) was found to be the most potent inhibitor. The enzyme assay showed the IC50 was 1.9 µM and the corresponding 95% confidence interval was from 1.7 to 2.2 µM. The whole-cell assay showed that compound 1 was cell permeable and inhibited LTC4 synthesis in a concentration dependent manner.

A novel prostacyclin agonist protects against airway hyperresponsiveness and remodeling in mice

Airway remodeling in bronchial asthma results from chronic, persistent airway inflammation. The effects of the reversal of airway remodeling by drug interventions remain to be elucidated. We investigated the effects of ONO-1301, a novel prostacyclin agonist with thromboxane inhibitory activity, on the prevention and reversibility of airway remodeling in an experimental chronic asthma model. Mice sensitized and challenged to ovalbumin (OVA) three times a week for 5 consecutive weeks were administered ONO-1301 or vehicle twice a day from the fourth week of OVA challenges. Twenty-four hours after the final OVA challenge, airway hyperresponsiveness (AHR) was assessed, and bronchoalveolar lavage was performed. Lung specimens were excised for staining to detect goblet-cell metaplasia, airway smooth muscle, and submucosal fibrosis. Mice administered ONO-1301 showed limited increases in AHR compared with mice administered the vehicle. The histological findings of airway remodeling were improved in ONO-1301-treated mice compared with vehicle-treated mice. Presumably, these therapeutic effects of ONO-1301 are attributable to the up-regulation of production of hepatocyte growth factor (HGF) in lung tissue, because the neutralization of HGF by antibodies prevented the effects of ONO-1301 on AHR and airway remodeling. Mice administered ONO-1301 showed similar levels of AHR and airway remodeling as mice administered montelukast, a cysteinyl-leukotriene-1 receptor antagonist, and lower levels were observed in mice administered dexamethasone. These data suggest that ONO-1301 exerts the effect of reversing airway remodeling, at least in part through an elevation of HGF in the lungs, and may be effective as an anti-remodeling drug in the treatment of asthma.

Bronchial allergen challenge using the Medicaid dosimeter

BACKGROUND

Bronchial allergen provocations are well established in asthma research. We evaluated the reproducibility of single-concentration, single-step allergen challenges in volunteers with grass pollen allergy.

METHODS

Forty-seven subjects underwent bronchial challenges using the aerosol provocation system nebulizer (Medicaid Sidestream) with incremental doses of grass pollen to define the individual allergen dose that causes a 20% drop in FEV(1) (PD(20)FEV(1)). In 39 subjects this procedure was followed by single-step challenges. Early and late asthmatic responses were monitored, and increases in exhaled nitric oxide were measured before and 24 h after single-step challenges.

RESULTS

After the first single-step challenge, the maximum drop in FEV(1) was 21.3% ± 8.0. A comparison of the drop in FEV(1) to the initial incremental challenge (29.7% ± 7.5) revealed an intraclass correlation of -0.30 (p < 0.05). In the second single-step challenge, the mean drop in FEV(1) was 20.9% ± 7.2. Compared with the first single-step challenge, the intraclass correlation was 0.37 (p < 0.05) and the 95% limits of agreement according to Bland and Altman were -17.5 to 18.1%. The increases in exhaled nitric oxide revealed substantial agreement in repeated single-step challenges (26.8 ppb ± 27.8 and 21.8 ppb ± 21.9, ICC 0.62, p < 0.001).

CONCLUSIONS

The use of aerosol provocation system to calculate the PD(20)FEV(1) allergen is a timesaving procedure and is less prone to errors because only one dilution of the allergen is used. The repeatability in well-defined subjects is excellent to study the mechanisms of allergen-induced airway inflammation and the development of new treatments for allergic diseases.

Airway disease: the use of large animal models for drug discovery

Large animal models have contributed to our current understanding of respiratory pathophysiology and the effects of pulmonary disease modifying drugs. For drug development, the benefit of using large animals over smaller animal species is primarily due to the greater similarity between humans and equivalent sized animals in terms of gross anatomy, morphometry, structure and physiology of their respiratory systems. Thus, when appropriate lung structure and function are required for correctly assessing the efficacy of novel drugs, large animals can play an important role in the development of these drugs to combat respiratory disease. The most widely used and best characterised large animal for drug development has been the sheep model of asthma. Recently, large animal models for chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) have been reported but thus far have not been used extensively for drug development. Some important limitations of using large animals are the large costs associated with this type of research, as well as the poorer understanding of disease mechanisms in these species relative to rodents. In this review we discuss the extent of correlations between preclinical testing performed in large animal models and the initial indication of clinical efficacy in ongoing clinical trials.

Cysteinyl leukotriene antagonism inhibits bronchoconstriction in response to hypertonic saline inhalation in asthma

BACKGROUND

In asthma, cysteinyl leukotrienes (CysLTs) play varying roles in the bronchomotor response to multiple provocative stimuli. The contribution of CysLTs on the airway's response to hypertonic saline (HS) inhalation in asthma is unknown. Whether polymorphisms in the leukotriene biosynthetic pathway affect the contribution of CysLTs to this response is also unknown.

METHODS

In a prospective, randomized, double-blind, placebo-controlled cross-over study, mild and moderate asymptomatic asthmatics underwent inhaled 3% HS challenge by doubling the duration of nebulization (0.5, 1, 2, 4, and 8 min) 2 h after one dose of montelukast (a CysLT receptor 1 [CysLTR1] antagonist) or placebo, and after three-week courses. We examined the effect of the leukotriene C(4) synthase (LTC(4)S) polymorphism (A-444C) on the efficacy of montelukast against HS inhalation in an exploratory manner.

RESULTS

In 37 subjects, 2 h after administration of montelukast, the mean provocative dose of HS required to cause a 20% drop in FEV(1) (HS-PD(20)) increased by 59% (9.17 ml after placebo vs. 14.55 ml after montelukast, p=0.0154). Three weeks of cysLTR1 antagonism increased the HS-PD(20) by 84% (10.97 vs. 20.21 ml, p=0.0002). Three weeks of CysLTR1 antagonism appeared to produce greater effects on blocking bronchial hyper-responsiveness (2 h vs. three-week HS-PD(20) values 14.55 vs. 20.21 ml respectively, p=0.0898). We did not observe an effect of the LTC(4)S polymorphism on the response to CysLTR1 antagonism in this cohort.

CONCLUSIONS

A significant proportion of HS-induced bronchoconstriction is mediated by release of leukotrienes as evidenced by substantial acute inhibition with a CysLTR1 antagonist. There was a trend toward greater inhibition of bronchial responsiveness with three weeks of therapy as opposed to acute CysLTR1 antagonism. Clinicaltrials.gov registration number NCT00116324.

CysLT1-R expression following allergen provocation in asthma and allergic rhinitis

Cysteinyl leukotrienes (CysLTs) contribute to allergic and inflammatory diseases through CysLT(1)-R. We aimed to assess CysLT(1)-R mRNA expression in induced sputum of rhinitics with or without asthma before and following allergen challenges. Both groups underwent nasal and "low dose" lung allergen challenges. Asthmatics also underwent "standard" lung challenge. Sputum was obtained before and at different time-points following the challenges for CysLT(1)-R, 5-lipoxygenase (5-LO), and eotaxin mRNA assessments. At baseline, there was no difference in mediator levels between groups. An increase in CysLT(1)-R mRNA (p=0.04) and a trend towards an increase in 5-LO and eotaxin (p=0.06 for both) at 24 h post-nasal challenge were observed. Following "low dose" lung allergen challenge, there was a trend towards an increase in CysLT(1)-R (p=0.07). In conclusion, CysLT(1)-R gene expression changes can be detected in sputum following allergen challenges. No difference was observed between groups, suggesting that changes in CysLT(1)-R expression occur whether or not the subject has concurrent asthma.

Montelukast in the treatment of asthma and beyond

Asthma is a chronic inflammatory disease affecting over 300 million people worldwide. The common association with allergic rhinitis and the presence of proinflammatory cells and mediators in the circulation of patients qualify asthma as a systemic disease. This characteristic and the fact that the gold-standard therapy for persistent asthma, inhaled corticosteroids, cannot suppress all components of airway inflammation and fail to adequately penetrate into the small airways, warrant the quest for effective systemic anti-asthma therapies. This review describes the most important controlled studies of montelukast, a once-daily leukotriene receptor antagonist, in asthma and allergic rhinitis in both adults and children. Montelukast is a systemically active drug with a targeted, dual mechanism of action, acting both as a bronchodilator and anti-inflammatory. In patients of all ages, montelukast has shown a favorable safety profile and was well-tolerated. Both as monotherapy or in combination with inhaled corticosteroids, montelukast produced clinically relevant improvements in asthma-related parameters, including symptoms, lung function parameters, quality of life and the number of asthma exacerbations. Furthermore, bronchoprotective effects have been reported both against specific and nonspecific bronchoactive stimuli. Similarly, in patients with allergic rhinitis, montelukast produced substantial improvements in symptoms and quality of life. Long-term studies aimed to determine its effects on airway remodeling are still lacking.

Montelukast in the treatment of asthma as a systemic disease

Asthma affects 300 million people worldwide. The common association of asthma with allergic rhinitis and the presence of proinflammatory mediators in the circulation of patients provide strong evidence for the need to treat asthma as a systemic disease. The leukotriene receptor antagonist montelukast is a disease-specific oral medication that has dual effects on airway smooth muscle cells and inflammatory processes. This review describes recent randomized, controlled studies of montelukast in asthma and allergic rhinitis in adults and children as young as 3 months old. Montelukast treatment consistently produced significant reductions in asthma exacerbations. While many patients may benefit from montelukast as monotheray, combination treatment for chronic asthma with inhaled corticosteroids is advocated as being rational. Significant improvements in symptoms and quality of life were observed in allergic rhinitis patients. Montelukast is well tolerated in patients of all ages. Long-term studies are underway to determine its effects on airway remodeling.

Add-on montelukast to inhaled corticosteroids protects against excessive airway narrowing

RATIONALE

Excessive airway narrowing in response to broncho-active stimuli is a predictor for severe exacerbations in asthma. Leukotriene receptor antagonists (LTRAs) have complementary properties to inhaled corticosteroids (ICS) on asthma control.

OBJECTIVES

The LTRA montelukast may provide an additional protection against excessive airway narrowing. We tested the add-on effects of montelukast on the maximal response plateau and PD(20) to inhaled methacholine in asthmatics on a stable dose of ICS.

METHODS

Thirty-one patients with allergic asthma [14M/17F, 19-50 years, forced expiratory volume in 1 s (FEV(1)) >70% pred., PD(20) <3.9 micromol methacholine], with a twice documented response plateau to methacholine, were randomized in a double-blind (montelukast 10 mg or matching placebo once daily), 12-week parallel study. Bronchoprovocation tests with methacholine (0.03-256 micromol or > or =40% decline in FEV(1)) were repeated every 4 weeks and after wash-out. The main study objectives were changes from baseline in maximal FEV(1) decline at the response plateau (i.e. >2 post-dose FEV(1) values within 5%) and PD(20) to methacholine after 12 weeks' treatment.

RESULTS

Neither treatment affected baseline FEV(1) (P=0.62). Compared with placebo, montelukast significantly decreased the maximal response plateau to methacholine (mean difference 9.4%; 95% confidence interval 3.9-15.7; P<0.005), improved the FEV(1) decline (mean change in FEV(1) decline was 2.1% [montelukast] and -0.8% [placebo], respectively, P<0.05), and increased PD(20) methacholine (mean change in PD(20) of 5.3 [montelukast] and 1.4 [placebo] doubling doses, respectively, P<0.001).

CONCLUSION

Add-on montelukast to ICS has disease-modifying effects in adults with persistent asthma, and hence reduces the risk of excessive airway narrowing (NCT 00913328).

Allergen-induced airway inflammation and its therapeutic intervention

Allergen inhalation challenge has been useful for examining the mechanisms of allergen-induced airway inflammation and the associated physiological changes and for documenting the efficacy of drugs to treat asthma. Allergen inhalation by a sensitized subject results in acute bronchoconstriction, beginning within 15-30 min and lasting 1-3 hr, which can be followed by the development of a late asthmatic response. Individuals who develop both an early and late response after allergen have more marked increases in airway hyperresponsiveness, and greater increases in allergen-induced airway inflammation, particularly in airway eosinophils and basophils. All of the currently available and effective treatments for asthma modify some aspects of allergen-induced responses. These medications include short-acting and long-acting inhaled β₂-agonists, inhaled corticosteroids, cromones, methylxanthines, leukotriene inhibitors, and anti-IgE monoclonal antibody. In addition, allergen inhalation challenge has become a useful method which can, in a very limited number of patients, provide key information on the therapeutic potential of new drugs being developed to treat asthma.

Montelukast and bronchial inflammation in asthma: a randomised, double-blind placebo-controlled trial

BACKGROUND

Examination of bronchoalveolar lavage, induced sputum, and peripheral blood indicate that cysteinyl leukotriene receptor blockers decrease inflammatory cells in asthma but these do not examine airway tissue per se.

OBJECTIVES

Our objective was to determine the effect of montelukast, a leukotriene receptor antagonist, on airway tissue inflammatory cells by direct bronchoscopic examination of the bronchial mucosa.

METHODS

Adult subjects with mild asthma (pre-bronchodilator FEV(1)> or =70% predicted; PC(20) of < or =4 mg/mL) were given 10mg/day oral montelukast (N=38) or placebo (N=37) for 6 weeks. Bronchial mucosal eosinophils and mast cells were identified and counted.

RESULTS

Change from baseline in numbers of biopsy EG2+ ("activated") eosinophils was the primary endpoint; numbers of total (chromotrope 2R+) eosinophils and (tryptase+) mast cells were secondary. Unexpectedly, there were many patients with zero EG2+ eosinophils at baseline. There was a within-group decrease in EG2+ cells, from 13.54 cells/mm (at baseline) to 0.79 cells/mm at 6 weeks in the montelukast group (LS mean change; 95% confidence interval=-13.59 [-25.45, -1.74]cells/mm; P<0.05), a change not observed in the placebo group (-1.17 [-13.26, 10.91]cells/mm; NS). The zero-inflated Poisson statistical model demonstrated that montelukast significantly reduced post-treatment EG2+ cells by 80% compared with placebo (95% CI [70.6-86.8%]; P<0.0001). The data for total eosinophils showed similar changes. The reduction in mast cell numbers was 12% (95% CI [7.9, 16.0]; P<0.0001).

CONCLUSION

Direct examination of airway tissue confirms that montelukast decreases the number of eosinophils and mast cells in asthma.

Eosinophil progenitors in airway diseases: clinical implications

Asthma, allergic rhinitis, nasal polyposis, chronic rhinosinusitis, and related forms of upper and lower airway diseases are often characterized by eosinophilic and basophilic inflammation, involving systemic processes. Eosinophil/basophil (Eo/B) lineage-committed progenitor cells in cord blood, peripheral blood, bone marrow, lung tissue, and sputum are up-regulated in the above conditions, and respond to allergen and other stimuli with increased differentiative and migratory capacity. A considerable body of evidence now exists showing that activation of such Eo/B-selective hemopoietic processes is not only associated with the onset and maintenance of allergic inflammation in atopic adults, but also with the development of the allergic diathesis. Moreover, eosinophilopoietic processes within hemopoietic compartments and, importantly, at mucosal tissue sites during an allergic inflammatory response provide novel targets for the treatment of allergy as a systemic process and disease.

The allergen bronchoprovocation model: an important tool for the investigation of new asthma anti-inflammatory therapies

Allergen bronchoprovocation tests have been used for more than two decades in the investigation of respiratory allergic diseases such as asthma and rhinitis. These bronchial challenges are now well standardized and can offer key information on the therapeutic potential of new agents and on their anti-inflammatory effects on the airways. Both standard and low-dose allergen provocations are safe when performed by experienced investigators and do not lead to persistent worsening of asthma or change in airway function. The evaluation of new therapeutic agents by these methods can also provide important information on the mechanisms of development and persistence of airway diseases.

Validated safety predictions of airway responses to house dust mite in asthma

BACKGROUND

House dust mite (HDM) is the most common aeroallergen causing sensitization in many Western countries and is often used in allergen inhalation challenges. The concentration of inhaled allergen causing an early asthmatic reaction [provocative concentration of inhaled allergen causing a 20% fall of forced expiratory volume in 1 s (FEV(1))(PC(20) allergen)] needs to be predicted for safety reasons to estimate accurately the severity of allergen-induced airway responsiveness. This can be accomplished by using the degree of non-specific airway responsiveness and skin sensitivity to allergen.

OBJECTIVE

We derived prediction equations for HDM challenges using PC(20) histamine or PC(20) methacholine and skin sensitivity data obtained from patients with mild to moderate persistent asthma and validated these equations in an independent asthma population.

METHODS

PC(20) histamine or PC(20) methacholine, skin sensitivity, and PC(20) allergen were collected retrospectively from 159 asthmatic patients participating in allergen challenge trials. Both the histamine and methacholine groups (n=75 and n=84, respectively), were divided randomly into a reference group to derive new equations to predict PC(20) allergen, and a validation group to test the new equations.

RESULTS

Multiple linear regression analysis revealed that PC(20) allergen could be predicted either from PC(20) methacholine only ((10)log PC(20) allergen=-0.902+0.741.(10)log PC(20) methacholine) or from PC(20) histamine and skin sensitivity (SS) ((10)log PC(20) allergen=-0.494+0.231.(10)log SS+0.546.(10)log PC(20) histamine). In the validation study, these new equations accurately predicted PC(20) allergen following inhalation of HDM allergen allowing a safe starting concentration of allergen of three doubling concentrations below predicted PC(20) allergen in all cases.

CONCLUSION

The early asthmatic response to inhaled HDM extract is predominantly determined by non-specific airway responsiveness to methacholine or histamine, whereas the influence of the cutaneous sensitivity to HDM appears to be rather limited. Our new equations accurately predict PC(20) allergen and hence are suitable for implementation in HDM inhalation studies.

Selective inducible nitric oxide synthase inhibition has no effect on allergen challenge in asthma

RATIONALE

Exhaled breath nitric oxide (Fe(NO)) is increased in asthma. NO is produced predominantly by inducible nitric oxide synthase (iNOS).

OBJECTIVES

We evaluated the selective and potent iNOS inhibitor GW274150 in asthma.

METHODS

Twenty-eight steroid-naive patients with asthma participated in a double-blind, randomized, double-dummy, placebo-controlled, three-period cross-over study. Subjects received GW274150 (90 mg), montelukast (10 mg), or placebo once daily for 14 days. Fe(NO) was assessed predose on Days 1, 7, 10, and 14. Adenosine 5'-monophosphate (AMP) challenge was performed on Day 10, allergen challenge on Day 14 followed by methacholine challenge (MCh) 24 hours later, and then bronchoscopy.

MEASUREMENTS AND MAIN RESULTS

GW274150 reduced predose Fe(NO) by 73, 75, and 71% on Days 7, 10, and 14, respectively, compared with placebo. Montelukast did not reduce Fe(NO). GW274150 did not inhibit AMP reactivity whereas for montelukast there was a trend toward inhibition: the mean doubling dose difference versus placebo was 0.64 (95% confidence interval [95% CI], 0 to 1.28). GW274150 did not inhibit early (EAR) and late (LAR) asthmatic responses to allergen, or MCh reactivity, despite reduced Fe(NO) levels. Montelukast inhibited EAR and LAR FEV1; the mean difference versus placebo for minimal FEV1 was 0.37 L (95% CI, 0.19 to 0.55) and 0.18 L (95% CI, 0.04 to 0.32), respectively. MCh reactivity was inhibited by montelukast (mean doubling dose difference vs. placebo, 0.51; 95% CI, 0.02 to 1.01). GW271540 also had no effect on inflammatory cell numbers in bronchoalveolar lavage fluid after allergen challenge.

CONCLUSIONS

Selective iNOS inhibition effectively reduces Fe(NO) but does not affect airway hyperreactivity or airway inflammatory cell numbers after allergen challenge in subjects with asthma. Clinical trial registered with www.clinicaltrials.gov (NCT00273013).

Montelukast decreased exhaled nitric oxide in children with perennial allergic rhinitis

BACKGROUND

Measurement of exhaled nitric oxide (eNO) is a simple and noninvasive method for assessment of inflammatory airway diseases. eNO is elevated in adolescent patients with perennial allergic rhinitis and related to bronchial hyperresponsiveness. The aim of this study was to investigate whether oral loratadine, montelukast, nasal budesonide or nasal sodium cromoglycate could reduce airway inflammation as indicated by decrease of eNO in children with perennial allergic rhinitis as demonstrated by eNO levels.

METHODS

A randomized and investigator-blinded study was conducted in a hospital-based outpatient clinic. Children with perennial allergic rhinitis were divided into four groups and treated by loratadine, loratadine with nasal sodium cromoglycate, loratadine with oral montelukast, and loratadine with nasal budesonide, respectively. Allergic rhinitis scores, eNO and peak expiratory flow were measured before and 2, 4, 6 and 8 weeks after treatment.

RESULTS

Results showed that eNO in children with perennial allergic rhinitis was reduced by nasal budesonide and oral montelukast within 2 weeks (24.56 +/- 14.42 vs 18.42 +/- 12.48, P < 0.001, in budesonide group; 27.81 +/- 13.4 vs 19.09 +/- 10.45, P < 0.001, in montelukast group), but not in the loratadine and cromoglycate groups. In contrast, loratadine or sodium cromoglycate also did not decrease eNO levels although they could decrease the symptom scores.

CONCLUSIONS

It was concluded that four common treatment modalities could effectively release symptom scores, but decrease of airway inflammation as determined by decrease of eNO might be only achieved by nasal budesonide and montelukast, but not nasal sodium cromoglycate and loratadine. Children with perennial allergic rhinitis with high eNO levels may require oral montelukast or nasal budesonide treatment to prevent airway hyperresponsiveness.

Effect of azelastine, montelukast, and their combination on allergen-induced bronchoconstriction in asthma

OBJECTIVES

Histamine and cysteinyl leukotrienes play an important role in early (EAR) and late (LAR) allergen reactions. Although protection by anti-histamines and anti-leukotrienes has been studied extensively, little is known about the effect of their combination. We, therefore, assessed the effect of clinically recommended doses of azelastine and montelukast alone and in combination on EAR and LAR.

METHODS

Seventeen patients (mean age 31 years, 14 m/3 f) with asthma and proven EAR and LAR received an oral dose of 4 mg azelastine twice daily, or 10mg montelukast once daily, or both for 1 week, in a double-blind, double-dummy, cross-over fashion. FEV(1) was measured after single-dose allergen challenges during EAR (0-2h) and LAR (2-9h).

RESULTS

Azelastine, montelukast and their combination protected against both EAR and LAR (p<0.004, each) by 46% and 43%, 76% and 59%, and 89% and 78%, respectively. Azelastine was not as effective during EAR but equally effective to montelukast during LAR. The combination was superior to each drug alone during both EAR and LAR (p<0.05, each).

CONCLUSION

The combination of azelastine and montelukast in clinically recommended doses has a greater effect in suppressing early and late allergen reactions than each drug alone.

Montelukast treatment attenuates the increase in myofibroblasts following low-dose allergen challenge

RATIONALE

Airway remodeling is believed to be important in the pathophysiology of asthma, and myofibroblasts are increased in the airways of asthmatic individuals 24 h after allergen challenge. Leukotriene receptor antagonists exert antiinflammatory activity in asthma, but it is unknown whether they influence indices of airway remodeling. In the present study, we evaluated the effect of montelukast on airway myofibroblasts following low-dose allergen challenge (LDAC).

METHODS

Stable subjects with mild asthma were included in a two-center, randomized, parallel-group study. A 2-week run-in period was followed by LDAC and endobronchial biopsy. Subjects were then randomized to receive either montelukast, 10 mg/d, or placebo (n = 10 in each group) for 8 weeks in a double-blind manner; at the end of the treatment period, subjects underwent a second LDAC and endobronchial biopsy. The effect of treatment on myofibroblasts, fibroblasts, and inflammatory cells was examined using electron microscopy techniques.

RESULTS

Treatment with montelukast showed no significant difference by comparison with placebo but did show a significant within-group treatment-related decrease in airway wall myofibroblasts not seen in the placebo group. In addition, the montelukast-treated group also showed a significant within-group reduction in lymphomononuclear cells and increased neutrophils.

CONCLUSIONS

The results suggest that montelukast has an inhibitory effect on airway structural cells that play a key role in airway remodeling in allergic airway inflammation, and that montelukast may be a useful therapy to attenuate airway remodeling in asthma.

The effect of a single inhaled dose of a VLA-4 antagonist on allergen-induced airway responses and airway inflammation in patients with asthma

Adhesion molecule very late antigen-4 (VLA-4) is implicated in the recruitment and activation of inflammatory cells in asthma, including eosinophils, T cells and mast cells. VLA-4 antagonists have been proposed as a new anti-inflammatory treatment modality for asthma. Therefore, we investigated whether a single inhaled dose of VLA-4 antagonist GW559090X could protect against allergen-induced changes in airway responses and airway inflammation in patients with asthma. We performed a randomized, double-blind, three-way crossover study with single inhaled doses of 3 mg of GW559090X, 500 microg of fluticasone propionate (FP) or placebo in 15 patients with mild intermittent asthma, controlled with short-acting beta(2)-agonists only. All patients developed a late asthmatic response (LAR) after allergen inhalation during screening. Study medication was administered 30 min prior to allergen challenge. Pre-dose and 24 h post-dose PC20 methacholine and levels of exhaled nitric oxide (eNO) were determined. At the given dose, VLA-4 antagonist GW559090X did not attenuate the early asthmatic response (EAR) when compared with placebo: mean AUC0-2 h(+/-SEM) (%fall h): 27.2+/-3.7 and 21.9+/-3.0 respectively (P=0.33); nor the LAR: mean AUC3-8 h(+/-SEM) (%fall h): 98.8+/-12.9 and 94.8+/-6.8 respectively (P=0.84). However, pretreatment with FP did attenuate both EAR and LAR when compared with placebo: mean AUC0-2 h11.6+/-3.3 (P=0.024) and mean AUC3-8 h 6.3+/-7.6 (P<0.001). None of these treatments had an effect on allergen-induced changes in airway hyper-responsiveness or eNO levels. These findings suggest that VLA-4 may not play a major role in allergen-induced airway responses and inflammation in asthma.

A critical appraisal of methods used in early clinical development of novel drugs for the treatment of asthma

Asthma is a heterogeneous disorder characterized by chronic airway inflammation, hyperresponsiveness and remodeling. Being the hallmark of asthma, airway inflammation has become the most important target for therapeutic agents. Consequently, during the past decade various semi-and non-invasive methods have been explored to sample the airway inflammation in asthma. In this review, we provide a practical overview of the current status of various sampling techniques including sputum induction, exhaled breath analysis, and bronchoprovocation tests (BPTs). We focus on their applicability for monitoring in clinical practice and in intervention trials in asthma.

Treatment of asthma with antileukotrienes: first line or last resort therapy?

Twenty five years after the structure elucidation of slow reacting substance of anaphylaxis, antileukotrienes are established as a new therapeutic modality in asthma. The chapter reviews the biochemistry and pharmacology of leukotrienes and antileukotrienes with particular focus on the different usage of antileukotrienes for treatment of asthma and rhinitis in Europe and the US. Further research needs and new areas for leukotriene involvement in respiratory diseases are also discussed.

Addition of inhaled corticosteroid on combined bronchodilator therapy in patients with COPD

PURPOSE

Bronchodilator therapy is the first step treatment in patients with COPD. The beneficial effects of corticosteroids either in health status or in airway inflammation in COPD have been previously studied. The aim of this study was to evaluate whether adding inhaled corticosteroids to combined bronchodilator therapy has additive clinical and anti-inflammatory effects in COPD patients.

SUBJECTS AND METHODS

Thirty patients with COPD were included in the study. All patients were receiving inhaled anticholinergic and long-acting beta-2 agonist. Inhaled corticosteroid (budesonide 800 microg daily) was added to their current medications for 12 weeks. Before and after this treatment period, spirometric values and arterial blood gas parameters were determined, blood was drawn for measurement of serum inflammatory markers and sputum was induced.

RESULTS

All patients were male, mean age was 67.7+/-8.7 years and duration of disease was 9.7+/-4.3 years. The induced sputum total cell counts, eosinophil and neutrophil counts decreased with corticosteroid treatment. The induced sputum IL-8 and TNF-alpha levels decreased significantly (IL-8; 835.9+/-217 versus 378.4+/-105 pg/ml, p=0.0001, TNF-alpha; 320.7+/-129 versus 201.3+/-52 pg/ml, p=0.003). Serum inflammatory markers and sputum LTB4 levels did not change with treatment.

CONCLUSION

These results suggested that the addition of inhaled corticosteroids to combined bronchodilator therapy might have anti-inflammatory effects in patients with COPD.

Bimosiamose, an inhaled small-molecule pan-selectin antagonist, attenuates late asthmatic reactions following allergen challenge in mild asthmatics: a randomized, double-blind, placebo-controlled clinical cross-over-trial

BACKGROUND

Asthma is characterized by increased recruitment of inflammatory cells from the circulation into the airways. As selectins mediate tethering and rolling of leukocytes on the vascular endothelium, they constitute a promising target for the therapeutic modulation of inflammation. We evaluated the effect of inhaled bimosiamose (TBC1269), a synthetic pan-selectin antagonist, on allergen-induced late asthmatic reactions (LAR) in mild asthmatics.

METHODS

Twelve male subjects with mild allergic asthma (only beta-agonists prn) with demonstrable LAR (fall of FEV1 3-8h after allergen inhalation >15% of baseline) at screening completed a randomized, double-blind, placebo-controlled clinical cross-over-trial. Subjects were treated with inhaled bimosiamose 70 mg bid or matching placebo on days 1-3 and 70 mg once on the morning of day 4. On day 4 following the last inhalation of study drug, an allergen challenge was performed. The primary endpoint was the maximum fall in FEV1 between 3 and 8h after allergen inhalation on active treatment vs. placebo. Secondary endpoints included early asthmatic response, exhaled nitric oxide, and airway hyperresponsiveness to methacholine 24h post allergen.

RESULTS

Bimosiamose significantly attenuated the maximum LAR compared to placebo by 50.2% (placebo mean+/-SEM fall -13.10+/-2.30%, bimosiamose -6.52+/-3.86%, treatment effect p=0.045; linear mixed-effects model). There was no effect of active treatment on early asthmatic response, post allergen airway hyperresponsiveness or exhaled nitric oxide, and peripheral blood cells.

CONCLUSIONS

Administration of the pan-selectin antagonist bimosiamose is effective in a human allergen challenge model of asthma. The result of this proof-of-concept exploratory trial is the first study that demonstrates clinical efficacy of selectin-antagonists as novel therapeutic strategy in asthma.

Effect of IVL745, a VLA-4 antagonist, on allergen-induced bronchoconstriction in patients with asthma

BACKGROUND

Very late antigen (VLA-4) antagonists have been proposed as potential therapies for diseases in which cell recruitment and accumulation are causative. Asthma, which is characterized by airway inflammation involving the accumulation of eosinophils and mononuclear cells, is one such disease.

OBJECTIVE

We sought to assess the effect of IVL745, a VLA-4 antagonist, on the early and late asthmatic response (LAR) and on markers of airway inflammation after allergen inhalation.

METHODS

The study was of a placebo-controlled, double-blind, randomized, 2-way crossover design. Sixteen subjects with mild-to-moderate asthma controlled with short-acting beta2-agonists only and with a LAR to inhaled allergen participated in the study. At one treatment period they took 20 mg of IVL745 and one treatment period placebo. Both treatments were taken twice daily for 7 days, with a single dose on day 8. Treatments were separated by a washout period of at least 2 weeks. On day 7 of each treatment period, sputum was induced and collected, and exhaled nitric oxide (NO) was measured. On day 8, an inhaled bolus allergen challenge was performed, and blood was taken for pharmacokinetics. On day 9, exhaled NO was measured, and a methacholine challenge was done. On day 10, sputum was induced and collected. Adverse events, peak expiratory flow (PEF), use of short-acting beta2-agonists, and asthma symptoms were recorded daily throughout the study.

RESULTS

There was no statistically significant difference between IVL745 and placebo in the effect on the LAR after allergen challenge, as measured by the area under the curve of the percentage change in FEV1 from the prechallenge baseline (mean [SEM], -81.99 [18.80] after IVL745 and -72.58 [21.29] after placebo; 95% CI of difference, -36 to 16.8; P = .46) or by the maximum percentage change from the prechallenge baseline (mean [SEM], -23.44 [4.73] after IVL745 and -21.30 [5.17] after placebo; 95% CI of difference, -11 to 6.29; P = .60). There was a statistically significant decrease in the percentage of eosinophils in sputum on day 7 of treatment with IVL745 (mean [SEM], 7.32 [1.46]) compared with placebo (mean [SEM], 15.00 [1.92]; 95% CI of difference, -13 to -1.2; P = .02). There was no statistically significant difference between IVL745 and placebo with respect to the early asthmatic response, methacholine hyperresponsiveness, exhaled NO, postallergen sputum, symptoms, inhaled beta2-agonist use, or PEF.

CONCLUSION

In patients with mild-to-moderate atopic asthma, IVL745 did not affect the early and late response to inhaled allergen or markers of airway inflammation, except for a modest reduction in sputum eosinophils.

Effect of combined montelukast and desloratadine on the early asthmatic response to inhaled allergen

BACKGROUND

The early asthmatic response (EAR) to inhaled allergen results from IgE-mediated release of multiple mast-cell mediators, including leukotrienes and histamine, both of which cause bronchoconstriction. Combination therapy directed at blocking the effects of both mediators might protect against the EAR better than either therapy alone.

OBJECTIVE

We sought to evaluate the effect of desloratadine and montelukast, administered alone and in combination, on the EAR to inhaled allergen.

METHODS

Ten adults with mild-to-moderate atopic asthma participated in a randomized, 4-way crossover study design comparing placebo, 5 mg of desloratadine, 10 mg of montelukast, and the combination administered at 26 hours and 2 hours before each allergen challenge conducted at least 7 days apart. The primary end point was the concentration of allergen that resulted in a 20% decrease in FEV1 (PC20).

RESULTS

The geometric mean allergen PC20 (mean log +/- SEM) for combination therapy, montelukast, desloratadine, and placebo was 697 U/mL (2.8433 +/- 0.3253), 338 U/mL (2.5295 +/- 0.2979), 123 U/mL (2.0883 +/- 0.2102), and 104 U/mL (2.0166 +/- 0.2553), respectively (n = 9; P < .00001, ANOVA). Montelukast increased the allergen PC20 4.8-fold, and combination therapy increased the allergen PC20 8.9-fold. The effect of the combination was greater than that with montelukast alone (P < .02). Desloratadine treatment was no different than placebo.

CONCLUSIONS

The early response to inhaled allergen was unchanged after desloratadine therapy and partially inhibited with montelukast therapy. The combination of desloratadine and montelukast provided superior efficacy to either blocker administered alone. Investigations into the possible mechanisms of the enhanced inhibition are necessary.

Inhaled corticosteroid effects both eosinophilic and non-eosinophilic inflammation in asthmatic patients

AIM: To determine induced sputum cell counts and interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-alpha) and leukotriene B4 (LTB4) levels as markers of neutrophilic inflammation in moderate persistent asthma, and to evaluate the response to inhaled steroid therapy. METHODS: Forty-five moderate asthmatic patients and 10 non-smoker controls were included in this study. All patients received inhaled corticosteroid (800 microg of budesonide) for 12 weeks. Before and after treatment pulmonary function tests were performed, and symptom scores were determined. Blood was drawn for analysis of serum inflammatory markers, and sputum was induced. RESULTS: Induced sputum cell counts and inflammatory markers were significantly higher in patients with asthma than in the control group. The induced sputum eosinophil counts of 12 patients (26%) were found to be less than 5%, the non-eosinophilic group, and sputum neutrophil counts, IL-8 and TNF-alpha levels were significantly higher than the eosinophilic group (neutrophil, 50+/-14% versus 19+/-10%, p<0.01). In both groups, there was a significant decrease in sputum total cell counts and serum and sputum IL-8, TNF-alpha and LTB4 levels after the treatment. There was no change in sputum neutrophil counts. Although the sputum eosinophil count decreased only in the eosinophilic subjects, there was no significant difference in inflammatory markers between the groups. The symptom scores were significantly improved after treatment, while the improvement did not reach statistical significance on pulmonary function test parameters. CONCLUSION: Notably, in chronic asthma there is a subgroup of patients whose predominant inflammatory cells are not eosinophils. Sputum neutrophil counts and neutrophilic inflammatory markers are significantly higher in these patients. In the non-eosinophilic group, inhaled steroid caused an important decrease in inflammatory markers; however, there was no change in the sputum eosinophil and neutrophil counts.

Biological effects of montelukast, a cysteinyl-leukotriene receptor-antagonist, on T lymphocytes

BACKGROUND

Montelukast (MNT), a cysteinyl-leukotriene receptor (Cys-LTR) antagonist, has anti-inflammatory activity in the treatment of allergic diseases. If this effect is due only to blocking leukotrienes or also owing to inhibiting proliferation and survival of inflammatory cells, is actually unknown.

OBJECTIVE

Testing the hypothesis that MNT could influence T lymphocyte functional behaviour in vitro.

METHODS

Normal T lymphocytes were analysed for surface expression of Cys-LTR(1) and Cys-LTR(2) by means of monoclonal antibodies (mAbs), in the resting state and after activation with T helper type 2 cytokine or T cell receptor (TcR) stimulation. Proliferative activity, as well as IL-4 andIFN-gamma production, were simultaneously determined in samples exposed to molar concentrations of MNT from 10(-8) to 10(-5). Programmed cell death in cultured samples was evaluated by means of propidium iodide and fluorescein isothiocyanate-conjugated anti-Annexin V mAb staining. The complementary DNA microarray technique was adopted to identify gene products involved in apoptosis induction.

RESULTS

Resting T cells expressed low levels of Cys-LTR. Upon anti-CD3 mAb activation, a progressive increase in Cys-LTR(1) and -LTR(2) expression was observed. Exposure to MNT reduced proliferative response to TcR engagement, increased IFN-gamma production and led to apoptosis at minimal concentrations of 10(-6) M. A progressive loss in BAD and B cell lymphoma/leukaemia-2 activities, and an increase in the expression of CD27, TRAF3, TRAIL, p53 and Fas genes were also observed.

CONCLUSIONS

Biological effects of MNT delineate a complex picture of gene activation and repression, probably induced by Cys-LTR blockade. The induction of apoptosis in allergen-specific T cell population, as a final result, appears fundamental in the treatment of asthma.

Effect of montelukast compared with inhaled fluticasone on airway inflammation

BACKGROUND

Inhaled corticosteroids are currently regarded as the gold standard in anti-inflammatory therapy, however, leukotriene receptor antagonists have been ascribed anti-inflammatory properties.

OBJECTIVE

We directly compared the anti-inflammatory effects of inhaled fluticasone propionate (FP, 100 microg Diskus, twice daily) and oral montelukast (MON 10 mg, nocte) in bronchial biopsies of patients with asthma in a double-blind, double-dummy, parallel-group design.

METHODS

Bronchial biopsies, serum and urine samples were collected from 36 atopic asthmatics before and after 8 weeks of treatment. Activated T cells (CD25+), eosinophils (MBP+) and mast cells (tryptase+) were analysed by immunohistochemistry. Serum eosinophil cationic protein (ECP) and IL-5 were analysed by radio and enzyme immunoassay (EIA), respectively. Urinary 9alpha-11beta-PGF2 and leukotriene E4 (LTE4) were measured by EIA.

RESULTS

A comparison of changes from baseline [FP/MON ratio (95% confidence interval)] of activated T cells was not different when subjects were treated with FP compared to treatment with MON [1.00 (0.18-4.86); P=0.924]. Following treatment, mast cells in the FP group were significantly lower than in the group treated with MON [0.39 (0.16-0.97); P=0.041]. There was no difference in the number of eosinophils in the lamina propria following either treatment [0.54 (0.05-2.57); P=0.263]. However, treatment with FP resulted in a significantly greater decrease in serum ECP, compared to treatment with MON [0.37 (0.25-0.71); P=0.002].

CONCLUSIONS

FP appears to be superior to MON as an anti-inflammatory therapy in mild asthmatics.

Differential effects of fluticasone and montelukast on allergen-induced asthma

Early asthmatic responses (EAR) and late asthmatic responses (LAR) to allergen are induced by the local release of a series of bronchoconstrictor mediators, including leukotrienes and histamine. Both anti-leukotrienes and other anti-asthma drugs, such as inhaled glucocorticoids, have been shown to reduce both EAR and LAR. The aim of the present study was to directly compare the effects of regular treatment with an oral anti-leukotriene, montelukast (Mont; 10 mg once daily, for 8 days), and an inhaled glucocorticoid [fluticasone propionate (FP) 250 microg twice daily for 8 days] on the EAR and LAR to an inhaled allergen challenge. Patients with a documented EAR and LAR at a screening visit were randomized to these treatments, or placebo, in a double-blind, double-dummy, crossover fashion. Allergen challenge at a dose causing both an EAR and LAR was given on the eighth day of treatment. The maximum fall in FEV1 during the EAR was 17.8% during placebo treatment, 8.3% during Mont and 16.3% during FP (P <0.05 for Mont vs placebo). The maximum fall during the EAR was 13.8% during placebo treatment, 11.8% during Mont and 2% during FP treatment (P <0.05 for FP vs placebo and FP vs Mont). PC20 methacholine was significantly higher 24 h after allergen challenge during FP-treatment compared with Mont (P <0.05). Both montelukast and fluticasone reduced the relative amount of sputum eosinophils after allergen compared with placebo treatment. This study shows that anti-leukotrienes are effective to attenuate the EAR, whereas inhaled glucocorticoids are more effective than anti-leukotrienes in attenuating the EARs and improves bronchial hyperresponsiveness to a greater extent. In conclusion, inhaled glucocorticoids have overall greater efficacy than oral anti-leukotrienes to attenuate allergen-induced airway responses in mild asthmatic patients.

Protective effect of montelukast on lower and upper respiratory tract responses to short-term cat allergen exposure

BACKGROUND

Challenge with short-term exposure to airborne cat allergen in sensitized patients produces pulmonary function changes and rhinitis symptoms.

OBJECTIVE

To determine the benefit of montelukast, 10 mg, for patients with concomitant asthma and allergic rhinitis as demonstrated by protection against both lower and upper airway responses to cat allergen challenge.

METHODS

This randomized, crossover study treated patients with montelukast vs placebo during two 2-week, double-blind treatment periods, separated by a 1-week washout period. After each treatment period, patients underwent a 60-minute or less exposure to high levels of airborne cat allergen. Lower and upper airway responses were measured by spirometry and symptom scores.

RESULTS

Of 52 patients with data from both treatment arms, 79% of patients taking montelukast and 67% taking placebo were exposed to the full 60-minute allergen challenge. Montelukast provided significant (P < or = .001) protection against allergen challenge in the lower airway coprimary end point of area under the curve during challenge (AUC0-60min) for percentage decrease in forced expiratory volume in 1 second: mean of 10.5% per hour and 14.7% per hour for montelukast and placebo, respectively. Although the effect on the overall nasal symptoms score (NSS) coprimary end point of AUC0-60min was not statistically significance (P = .12), nasal congestion during the challenge and NSS during recovery showed statistically significant (P = .048) protection by montelukast. Additional analyses of simultaneous lower and upper airway responses showed that more patients taking montelukast (22, 43%) vs placebo (13, 26%) were protected from both asthma and rhinitis (P = .02), with an odds ratio of 2.24 (95% CI, 1.16-4.32) in favor of montelukast.

CONCLUSIONS

Montelukast has a protective effect against both lower and upper airway responses during exposure to high levels of cat allergen.