Effects of cysteinyl leukotrienes and leukotriene receptor antagonists on markers of inflammation

Antagonism of cysteinyl leukotriene receptor 1 (cysLTR1) by montelukast suppresses cell senescence of chondrocytes

Aging is closely associated with osteoarthritis (OA). Although its underlying mechanisms remain unknown, cellular senescence in chondrocytes has become an important therapeutic target for the treatment of OA. Cysteinyl leukotriene receptors (cysLTRs) mediate the pathobiological function of cysteinyl leukotrienes (cysLTs). However, the roles of cysLTRs in the pathogenesis of OA have not been reported before. In the current study, we found that cysLTR1 but not cysLTR2 is expressed in human primary chondrocytes. In addition, stimulation with tumor necrosis factor α (TNF-α) resulted in a significant increase in the expression of cysLTR1. Interestingly, montelukast, a specific cysLTR1 antagonist, attenuated TNF-α-induced up-regulation of the activity of senescence-associated β-galactosidase (SA-β-Gal). In addition, TNF-α led to cell cycle arrest at the G0/G1 phase, which was prevented by treatment with montelukast. Notably, montelukast reduced expression of the senescence markers p53, p21 and PAI-1. In addition, montelukast ameliorated TNF-α-induced K382 acetylation of p53 by promoting the expression of SIRT1. Silencing of SIRT1 using SIRT1 siRNA broke the inhibitory effects of montelukast on K382 acetylation of p53. Importantly, silencing of cysLTR1 reversed the reduction of SIRT1 expression as well as the K382 acetylation of p53. Our findings strongly implicate that cysLTR1 has the capacity to regulate cellular senescence in chondrocytes. It is suggested that montelukast may be a potential therapeutic agent for chondro-protective therapy.

Cysteinyl Leukotrienes as Potential Pharmacological Targets for Cerebral Diseases

Cysteinyl leukotrienes (CysLTs) are potent lipid mediators widely known for their actions in asthma and in allergic rhinitis. Accumulating data highlights their involvement in a broader range of inflammation-associated diseases such as cancer, atopic dermatitis, rheumatoid arthritis, and cardiovascular diseases. The reported elevated levels of CysLTs in acute and chronic brain lesions, the association between the genetic polymorphisms in the LTs biosynthesis pathways and the risk of cerebral pathological events, and the evidence from animal models link also CysLTs and brain diseases. This review will give an overview of how far research has gone into the evaluation of the role of CysLTs in the most prevalent neurodegenerative disorders (ischemia, Alzheimer's and Parkinson's diseases, multiple sclerosis/experimental autoimmune encephalomyelitis, and epilepsy) in order to understand the underlying mechanism by which they might be central in the disease progression.

Differences in urinary leukotriene E4 levels and distribution of eosinophils between chronic rhinosinusitis patients with aspirin-intolerant and -tolerant asthma

OBJECTIVE

Urinary leukotriene E4 (U-LTE4) concentrations are significantly elevated in patients with aspirin-intolerant asthma (AIA). However, the relationship between the clinicopathogenetic features of eosinophilic rhinosinusitis and U-LTE4 concentration remains unknown. Here we examined the relationship between U-LTE4 level and eosinophil in chronic rhinosinusitis.

METHODS

We measured the U-LTE4 concentrations and eosinophil counts in ethmoidal and maxillary sinuses and peripheral blood in 30 asthmatic patients (including 15 AIA patients).

RESULTS

Eosinophil counts in ethmoidal sinuses and peripheral blood were markedly higher in asthmatic patients than in controls. Although there were no significant differences between eosinophil counts in maxillary and ethmoidal sinuses for ATA group, eosinophil counts were higher in ethmoidal sinus compared to that in maxillary sinus in the AIA group (P<.05). Eosinophil counts were higher in the maxillary than in ethmoidal sinuses for control patients (P<.05). Despite low correlation between eosinophil counts in peripheral blood and eosinophil counts in maxillary sinus (rs=0.4323, P<.001), moderate correlation was observed between eosinophil counts in peripheral blood and eosinophil counts in ethmoidal sinus (rs=0.5249, P<.0001). Basal U-LTE4 concentrations were higher in AIA patients than in those with aspirin-tolerant asthma. Despite low correlation between eosinophil counts and U-LTE4 concentration in maxillary sinus (rs=0.3849, P<.01), moderate correlation was observed between eosinophil counts and U-LTE4 concentrations in ethmoidal sinus (rs=0.4736, P<.001).

CONCLUSION

We describe the differences in U-LTE4 and other parameters in AIA compared to ATA, and correlation among parameters. We demonstrate that eosinophil-dominant inflammation starts in ethmoidal sinus clinicopathogenetically in CRS with asthma. U-LTE4 concentration was not exclusively associated with eosinophil counts in ethmoidal sinus. Eosinophils in ethmoidal sinus may be a major production site for CysLTs, particularly in AIA. CRS with AIA is assumed to be characterized by leukotriene-eosinophil cross-interaction in ethmoidal sinus.

A highly efficient, high-throughput lipidomics platform for the quantitative detection of eicosanoids in human whole blood

We have developed an ultra-performance liquid chromatography-multiple reaction monitoring/mass spectrometry (UPLC-MRM/MS)-based, high-content, high-throughput platform that enables simultaneous profiling of multiple lipids produced ex vivo in human whole blood (HWB) on treatment with calcium ionophore and its modulation with pharmacological agents. HWB samples were processed in a 96-well plate format compatible with high-throughput sample processing instrumentation. We employed a scheduled MRM (sMRM) method, with a triple-quadrupole mass spectrometer coupled to a UPLC system, to measure absolute amounts of 122 distinct eicosanoids using deuterated internal standards. In a 6.5-min run, we resolved and detected with high sensitivity (lower limit of quantification in the range of 0.4-460 pg) all targeted analytes from a very small HWB sample (2.5 μl). Approximately 90% of the analytes exhibited a dynamic range exceeding 1000. We also developed a tailored software package that dramatically sped up the overall data quantification and analysis process with superior consistency and accuracy. Matrix effects from HWB and precision of the calibration curve were evaluated using this newly developed automation tool. This platform was successfully applied to the global quantification of changes on all 122 eicosanoids in HWB samples from healthy donors in response to calcium ionophore stimulation.

Polymorphisms of the PTGDR and LTC4S influence responsiveness to leukotriene receptor antagonists in Korean children with asthma

Activation of the prostaglandin D2 receptor (PTGDR) may contribute to pulmonary vasodilation, bronchoconstriction, recruitment of eosinophils, basophils and T-lymphocytes, and enhanced synthesis of leukotriene C4. We investigated whether polymorphisms of the leukotriene C4 synthase (LTC4S) -444A/C and PTGDR -441T/C were associated with clinical phenotypes and responsiveness to leukotriene receptor antagonist (LTRA) in Korean asthmatic children. We enrolled 270 normal and 870 asthmatic children. We prescribed montelukast (5 mg per day) to 100 of asthmatic children, and analyzed the responsiveness to LTRA by exercise challenge tests. Polymorphisms were genotyped by PCR-restriction fragment length polymorphism. As the number of minor alleles of the PTGDR -441T/C and LTC4S -444A/C polymorphisms increased, the log total eosinophil counts increased in atopic asthmatic children (P-value=0.03). We found a significant association between responsiveness to montelukast and the PTGDR polymorphism (P-value=0.038). However, the LTC4S -444A/C and PTGDR -441T/C were not associated with the susceptibility for asthma (LTC4S, AA versus AC+CC, adjusted odds ratio of 0.98 (95% confidence interval, 0.73-1.31); PTGDR, TT versus TC+CC, adjusted odds ratio of 0.90 (95% confidence interval, 0.68-1.19)) or clinical phenotypes (P-value>0.05). The effects of the PTGDR and LTC4S polymorphisms on the enhancement of eosinophil counts were additive in the Korean children with asthma. In addition, the PTGDR polymorphism seems to be associated with the responsiveness to LTRA. Therefore, therapies that target the PTGDR may be useful for modulating the responsiveness to LTRA.

What's new in asthma pathophysiology and immunopathology?

Research on asthma pathophysiology over the past decade has expanded the complex repertoire involved in the pathophysiology of asthma to include inflammatory, immune and structural cells, as well as a wide range of mediators. Studies have identified a role for connective and other mesenchymal tissues involved in airway remodeling. Recent findings have implicated the innate immune response in asthma and have revealed interesting patterns of interaction between the innate and adaptive immune response and the associated complex chronic inflammatory reaction. New immune cell populations have also been added to this repertoire, including Tregs, natural killer T cells and Th17 cells. The role of the eosinophil, a prominent pathological feature in most asthma phenotypes, has also been expanding to include roles such as tissue modifiers and immune regulators via a number of fascinating and hitherto unexplored mechanistic pathways. In addition, new and significant roles have been proposed for airway smooth muscle cells, fibroblasts, epithelial and endothelial cells. Tissue remodeling is now considered an integral element of asthma pathophysiology. Finally, an intricate network of mediators, released from both immune and inflammatory cells, including thymus stromal lymphopoietin and matrix metalloproteinases, have added to the complex milieu of asthma immunity and inflammation. These findings have implications for therapy and the search for novel strategies towards better disease management. Sadly, and perhaps due to the complex nature of asthma, advances in therapeutic discoveries and developments have been limited. Thus, understanding the precise roles played by the numerous dramatis personae in this odyssey, both individually and collectively within the context of asthma pathophysiology, continues to pose new challenges. It is clear that the next stage in this saga is to embark on studies that transcend reductionist approaches to involve system analysis of the complex and multiple variables involved in asthma, including the need to narrow down the phenotypes of this condition based on careful analysis of the organs (lung and airways), cells, mediators and other factors involved in bronchial asthma.

Pitrakinra for asthma

IMPORTANCE OF THE FIELD

In asthma IL-4 and IL-13 have been demonstrated to play major pathogenic roles and therefore their blockade would potentially represent a plausible therapeutic approach.

AREAS COVERED IN THIS REVIEW

Pitrakinra is a dual IL-4/IL-13 inhibitor currently under development for asthma and the existing preclinical and clinical data are discussed.

WHAT THE READER WILL GAIN

Inhaled pitrakinra demonstrated a good anti-inflammatory potential and a good safety profile on a short-term basis but its place in asthma therapy is still to be found.

TAKE HOME MESSAGE

Specific anticytokine therapies might in the near future reshape asthma therapy.

Levels of cysteinyl-leukotrienes in exhaled breath condensate are not due to saliva contamination

BACKGROUND AND AIMS

Saliva contamination has been suggested to be a major contributor to levels of cysteinyl leukotrienes in exhaled breath condensate (EBC). The aim of this study was to compare the levels of cysteinyl-leukotrienes (CysLT) and alpha-amylase activity in EBC to induced sputum and saliva collected from the same subjects (asthmatics and control). We thereby aimed to find out whether saliva contamination could be a plausible explanation to the levels found in EBC or not.

METHODS

EBC, saliva and induced sputum were collected from 11 asthmatic and 19 healthy adults. These samples were analyzed for CysLT concentration and alpha-amylase activity.

RESULTS

No significant correlation was found between CysLT concentration and alpha-amylase activity in EBC, saliva or sputum. In addition, we show that the saliva contamination (measured as alpha-amylase activity) was negligible, as the relative amount of saliva CysLT was only 0.6% of that found in EBC. The amount of CysLT correlated between all three compartments (EBC, saliva and sputum), but no similar correlation was seen for the alpha-amylase activity in EBC compared to saliva and sputum. The levels of CysLT were higher in asthmatic patients compared to healthy controls in EBC, saliva and sputum.

CONCLUSION

We conclude that the amount of CysLT in EBC cannot be explained by saliva contamination. Please cite this paper as: Tufvesson E, van Weele LJ, Ekedahl H and Bjermer L. Levels of cysteinyl-leukotrienes in exhaled breath condensate are not due to saliva contamination.

Pharmacophore identification, synthesis, and biological evaluation of carboxylated chalcone derivatives as CysLT1 antagonists

The pharmacophore model (Hypo1) with a well prediction capacity for CysLT(1) antagonists was developed using Catalyst/HypoGen program. Virtual screening against an in-house database consisted of carboxylated chalcones using Hypo1 was performed. Retrieved hits 26a, 26b, 27a, and 27b were synthesized and biological evaluated, the results of which demonstrated that these compounds showed moderate to good CysLT(1) antagonistic activities. This study indicated that the generated model (Hypo1) is a reliable and useful tool in lead optimization for novel CysLT(1) antagonists.

Exhaled leukotrienes and bronchial responsiveness to methacholine in patients with seasonal allergic rhinitis

BACKGROUND

Allergic rhinitis and bronchial asthma can coexist and affect each other.

OBJECTIVE

To investigate the relationship between the postseasonal increase in the concentration of leukotriene (LT) B4 and LTE4 in exhaled breath condensate (EBC) and bronchial responsiveness to methacholine (BRM) in patients with seasonal allergic rhinitis (SAR).

METHODS

In 28 patients with SAR and 50 healthy study patients, the leukotrienes were measured in EBC during and after the pollen season by gas chromatography/mass spectrometry. The BRM was determined after the pollen season.

RESULTS

In 7 patients with SAR, significantly increased concentrations of both the leukotrienes were found in EBC during and 5 months after the pollen season. The following seasonal and postseasonal median values were measured in patients with SAR in comparison with control patients: LTB4: 131 and 90 pg/mL vs 80 and 79 pg/mL, P < .001 and P = .03, respectively; LTE4: 122 and 86 pg/mL vs 76 and 74 pg/mL, P < .001 and P = .02, respectively. Five months after the pollen season, the concentrations of LTB4 and LTE4 decreased with respect to their seasonal values (90 and 86 pg/mL, respectively, P < .001, for both leukotrienes). In 7 patients with SAR and leukotriene levels exceeding the reference limits, significantly increased BRM was also found (LTB4: P = .02; LTE4: P = .002).

CONCLUSIONS

The seasonal and postseasonal increases in LTB4 and LTE4 concentrations in EBC of the patients with SAR correlated significantly with the later increase in BMR. This relationship could provide a useful predictive parameter for early inflammatory processes in the lower airways of patients with allergic rhinitis.

Pretreatment with albuterol versus montelukast for exercise-induced bronchospasm in children

STUDY OBJECTIVES

To compare pretreatment with albuterol versus montelukast added to the current asthma regimen for protection against exercise-induced bronchospasm in children with mild-to-moderate asthma, and to determine whether cysteinyl leukotriene (Cys-LT) concentrations measured in the exhaled breath condensate correlated with response to montelukast.

DESIGN

Prospective, randomized, double-blind, double-dummy, crossover study.

SETTING

Asthma clinic at a university-affiliated medical center.

PATIENTS

Eleven children aged 7-17 years with physician-diagnosed mild-to-moderate asthma for at least 6 months and with self-reported exercise-induced bronchospasm (defined as > or = 15% decrease in forced expiratory volume in 1 sec [FEV(1)] at screening and baseline visit).

INTERVENTION

Patients were randomly assigned to receive 3-7 days of oral montelukast 5-10 mg/day or 2 puffs of an albuterol metered-dose inhaler just before an exercise challenge and then were crossed over to the alternate therapy for the last visit.

MEASUREMENTS AND MAIN RESULTS

Serial spirometry was performed before and at 0, 5, 10, 15, 30, 45, and 60 minutes after the exercise challenge at each visit. Measurement of exhaled breath condensate was performed at the screening visit and study visits 1 and 2. The primary outcome was the maximum change in FEV(1) after exercise. Secondary outcomes were the area under the curve for FEV(1) (expressed as percentage decrease from baseline) during the first 60 minutes (AUC(0-60)) after exercise and the proportion of patients in whom exercise-induced bronchospasm was prevented (defined as < 15% decrease in FEV(1) after exercise challenge). The mean +/- SD maximum decrease in FEV(1) was 27.5 +/- 7.9% at baseline. Patients receiving montelukast had an 18.3 +/- 13.7% decrease in FEV(1) compared with 0.7 +/- 1.6% in patients receiving albuterol (p=0.002, paired t test). Exercise-induced bronchospasm was prevented in 100% of the patients receiving albuterol compared with 55% receiving montelukast (p<0.05, McNemar's test). The AUC(0-60) was significantly smaller with albuterol compared with montelukast (p<0.001, Wilcoxon signed rank test). No correlations were found between Cys-LT concentration and the severity of exercise-induced bronchospasm or the response to montelukast.

CONCLUSION

Pretreatment with albuterol is more effective than montelukast for prevention of exercise-induced bronchospasm in children with asthma.

Antileukotrienes as adjunctive therapy in acute asthma

The leukotriene receptor antagonists (LTRAs) are a comparatively new class of asthma drugs that exhibit both bronchodilator and anti-inflammatory properties. There is a substantial body of evidence for their benefit in the management of chronic asthma in both adults and children, and particularly in specific types of asthma such as exercise-induced and aspirin-sensitive asthma. Despite best practice using current treatment guidelines for the management of acute asthma, a significant proportion of patients require continued treatment and are unable to be discharged from the emergency department; many require a short course of oral corticosteroids. The relatively rapid onset of action of LTRAs after oral administration and their additive effect to beta(2)-adrenoceptor agonists led to the hypothesis that they might be of benefit in acute asthma. This review examines the available evidence for the effect of LTRAs in acute asthma. Although the evidence is limited, it suggests that treatment with LTRAs provides additional bronchodilator effect to nebulised and inhaled beta(2)-adrenoceptor agonists. Short-term therapy with LTRAs results in fewer treatment failures and readmissions for patients with acute asthma, and less need for additional therapies such as nebulisers and corticosteroids.

Cysteinyl-leukotrienes and their receptors in asthma and other inflammatory diseases: critical update and emerging trends

Cysteinyl-leukotrienes (cysteinyl-LTs), that is, LTC4, LTD4, and LTE4, trigger contractile and inflammatory responses through the specific interaction with G protein-coupled receptors (GPCRs) belonging to the purine receptor cluster of the rhodopsin family, and identified as CysLT receptors (CysLTRs). Cysteinyl-LTs have a clear role in pathophysiological conditions such as asthma and allergic rhinitis (AR), and have been implicated in other inflammatory conditions including cardiovascular diseases, cancer, atopic dermatitis, and urticaria. Molecular cloning of human CysLT1R and CysLT2R subtypes has confirmed most of the previous pharmacological characterization and identified distinct expression patterns only partially overlapping. Interestingly, recent data provide evidence for the immunomodulation of CysLTR expression, the existence of additional receptor subtypes, and of an intracellular pool of CysLTRs that may have roles different from those of plasma membrane receptors. Furthermore, genetic variants have been identified for the CysLTRs that may interact to confer risk for atopy. Finally, a crosstalk between the cysteinyl-LT and the purine systems is being delineated. This review will summarize and attempt to integrate recent data derived from studies on the molecular pharmacology and pharmacogenetics of CysLTRs, and will consider the therapeutic opportunities arising from the new roles suggested for cysteinyl-LTs and their receptors.

A functional G300S variant of the cysteinyl leukotriene 1 receptor is associated with atopy in a Tristan da Cunha isolate

Atopy is a well-defined immune phenotype that is reported to be a risk factor for asthma. Among the many loci that contribute to a genetic predisposition to asthma, the cysteinyl leukotriene receptor genes and their variants have been important subjects of study because they are functionally and pharmacologically implicated in the atopy phenotype affecting many asthma subjects. Moreover, the product of cysteinyl-leukotriene 1 receptor gene (CysLT1), located at Xq13.2, is targeted by LT receptor antagonists. In our earlier association study, the M201V variant of the cysteinyl-leukotriene 2 receptor gene (CysLT2), located at 13q14, was implicated in atopic asthma. Here we report the screening of the coding region of the CysLT1, gene in the highly asthmatic Tristan da Cunha population. In this population, we discovered a CysLT1 G300S variant that is carried with a significantly higher frequency in atopics and asthmatics from the Tristan da Cunha population. Furthermore, we report the asthma independent association of the CysLT1 G300S variant with atopy. Subsequently, we compared the changes conferred by each SNP on CysLT function. The CysLT1 300S receptor interacts with LTD4 with significantly greater potency. For the 300S variant, a statistically significant decrease in the effector concentration for half-maximum response (EC50) for intracellular Ca flux and total InsP generation is observed. Other aspects of the receptor function and activity, such as desensitization, pharmacologic profile in response to montelukast, and cellular localization, are unchanged. These in vitro analyses provide evidence that the 300S CysLT1 variant, found more commonly in atopics in the Tristan da Cunha population, encodes a functionally more sensitive variant.

Effects of montelukast compared to double dose budesonide on airway inflammation and asthma control

Many patients with asthma remain symptomatic with impaired airway function on inhaled steroids. This study investigates the relationship between the clinical effect seen in response to additional treatment and the effect on airway inflammatory indices. Seventy-five adult asthmatic patients, incompletely controlled on 800 mcg budesonide/day, were randomised following a 4 week run-in period, to a double-blind, multi-centre controlled clinical trial of doubling inhaled corticosteroid (budesonide 1600 mcg/day) or adding 10mg montelukast for 12 weeks. Induced sputum was collected at baseline and end of treatment and analysed for eosinophil and neutrophil percentages, leukotrienes C4, D4 and E4, IL-8, Eosinophil Cationic Protein (ECP) and histamine. Sputum evidence of inflammation (2.0% eosinophils) was seen in only 29% of these patients and the percentage of eosinophils and other markers of airway inflammation did not change over the study period in either treatment group. There were significant improvements in am PEF (montelukast: 31.7 L/min, budesonide: 32.3 L/min) and quality of life with both treatments. We conclude that while both treatments showed similar improvements in lung function and quality of life, there was no evidence from these sputum markers measured that the effects were mediated via a reduction in airway inflammation or that the level of pre-treatment markers was associated with outcome.

The Basic Science of Wound Healing

Understanding wound healing today involves much more than simply stating that there are three phases: "inflammation, proliferation, and maturation." Wound healing is a complex series of reactions and interactions among cells and "mediators." Each year, new mediators are discovered and our understanding of inflammatory mediators and cellular interactions grows. This article will attempt to provide a concise report of the current literature on wound healing by first reviewing the phases of wound healing followed by "the players" of wound healing: inflammatory mediators (cytokines, growth factors, proteases, eicosanoids, kinins, and more), nitric oxide, and the cellular elements. The discussion will end with a pictorial essay summarizing the wound-healing process.

Treating asthma: is there a place for leukotriene receptor antagonists?

Asthma is a chronic disorder, characterized by airway hyperresponsiveness (AHR), airway inflammation and airway remodelling. Evidence has been provided for a relationship between pathophysiology, airway inflammation and remodelling. Moreover, these asthma features have been shown to respond to anti-inflammatory therapy. According to current guidelines, monitoring of asthma is predominantly based on symptoms and lung function data. However, these parameters appeared as poor indices for asthma control. Alternatively, asthma control relates well to exacerbations and (anamnestic) surrogate biomarkers of airway inflammation. Hence, appropriate treatment of asthma should primarily target the airway inflammation. According to current guidelines for asthma management, anti-inflammatory therapy with inhaled corticosteroids (ICS) is the cornerstone in the treatment of persistent asthma. To further optimize asthma control, add-on therapy with long-acting beta2-agonists (LABA) or leukotriene receptor antagonists (LTRA) should be combined with low to high doses of ICS. While the first combination focuses on optimal control of symptoms and lung function, the second provides a more complete suppression of the airway inflammation. In this paper we discuss treatment of asthma according to current guidelines versus new insights, addressing practical issues.

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.