Responsiveness to montelukast is associated with bronchial hyperresponsiveness and total immunoglobulin E but not polymorphisms in the leukotriene C4 synthase and cysteinyl leukotriene receptor 1 genes in Korean children with exercise-induced asthma (EIA)

BACKGROUND: As previous studies have shown that cysteinyl leukotrienes are important mediators in exercise-induced bronchoconstriction (EIB), and leukotriene receptor antagonists (LTRAs) such as montelukast have been shown to improve post-exercise bronchoconstrictor responses, we herein investigated whether clinical responsiveness to montelukast was associated with polymorphisms in the genes encoding leukotriene C4 synthase (LTC4S) and cysteinyl leukotriene receptor 1 (CysLTR1) and/or clinical parameters in Korean asthmatic children with EIB. METHODS: The study population consisted of 100 asthmatic children with EIB. The individuals studied were given exercise challenge tests before and after receiving montelukast (5 mg/day) for 8 weeks. Responders were defined as children showing>10% post-treatment improvement in forced expiratory volume in 1 s (FEV1). The LTC4S A(-444)C and CysLTR1 T(+927)C polymorphisms were genotyped by PCR-restriction fragment length polymorphism analysis. RESULTS: Of 100 enrolled children, 68 were classified as responders and 32 were classified as non-responders. No significant association was observed between montelukast responsiveness and LTC4S or CysLTR1 genotype, either alone or in combination. In contrast, montelukast-induced improvement in FEV(1) after exercise was correlated with higher pre-treatment PC20 (methacholine) values (r=0.210, P=0.036) and lower total IgE levels (r=-0.216, P=0.031). CONCLUSIONS: The LTC4S A(-444)C and CysLTR1 T(+927)C genotypes do not appear to be useful for predicting clinical responsiveness to montelukast, whereas bronchial hyperresponsiveness and total IgE appear to predict the degree of montelukast responsiveness in Korean asthmatic children with EIB.     

TBXA2R gene polymorphism and responsiveness to leukotriene receptor antagonist in children with asthma

Background Thromboxane A2 receptor (TBXA2R) gene polymorphism has been associated with atopy and asthma, but few studies have reported the effect of this gene polymorphism on asthma‐related phenotype or responsiveness to leukotriene receptor antagonist (LTRA) in asthmatic children. This study investigated associations between asthma‐related phenotypes and TBXA2R polymorphism, and also analysed whether the TBXA2R polymorphism has an effect on the efficacy of the LTRA, montelukast, in asthmatic children with exercise‐induced bronchoconstriction (EIB). Methods Asthmatic children (n=695) and control children (n=159) were evaluated for asthma‐related phenotypes including total IgE, pulmonary function test, and bronchial hyperresponsiveness to methacholine or exercise. Genotypes were detected by PCR‐RFLP. In the montelukast study, exercise challenge was performed before and after an 8‐week montelukast treatment. Results The TBXA2R polymorphism was not associated with asthma susceptibility and the clinical parameters of asthma. However, asthmatic children with combinations of the TBXA2R+795T>C and +924T>C risk alleles had significantly higher total IgE levels (P=0.01), total eosinophil counts (P<0.01) and lower forced expiratory volume in 1 s (FEV₁) (P=0.02) and forced expiratory rates at 25–75% of vital capacity (P=0.02) than those carrying the common alleles. When compared with individuals with the common alleles, patients with the TBXA2R+924T>C TT homozygote and TBXA2R+795T>C hetero‐ or homozygote (CT or CC) had a 3.67‐fold poor response to 8‐week montelukast treatment with respect to maximum percent fall in FEV₁ after exercise (odds ratio, 3.67; 95% confidence interval, 1.15–11.15). Conclusions A combined effect of TBXA2R+795T>C and +924T>C risk alleles may be linked to IgE production, eosinophilic inflammation, and severity of asthma. In addition, the TBXA2R+795T>C genotype may be a predictive marker of a clinical response to the LTRA in Korean asthmatic children with EIB.     

LTC4-synthase A-444C polymorphism: lack of association with NSAID-induced isolated periorbital angioedema in a Spanish population.

BACKGROUND: The mechanism of nonsteroidal anti-inflammatory drug (NSAID)-induced reactions is unknown. However, strong evidence supports the hypothesis of an enhanced production of cysteinyl-leukotrienes. The existence of a polymorphism (A-444C) in the promoter region of the leukotriene (LT)C4-synthase gene (the terminal enzyme in the LTC4 production pathway) has been reported. This polymorphism has yielded contradictory results on its association with aspirin-induced asthma. OBJECTIVE: The present study was designed to investigate the possible genetic association of C(-444) allele and a specific clinical phenotype of NSAID sensitivity, the NSAID-induced isolated periorbital angioedema, via a case/control study. METHODS: The polymorphism A-444C was analyzed in 58 patients with NSAID-induced periorbital angioedema and 61 control subjects, who had undergone single-blind, placebo-controlled oral challenge. Genotype was determined by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: We have not found an association of C(-444), allele with NSAID-induced isolated periorbital angioedema. CONCLUSIONS: Further studies are needed to determine whether polymorphisms in the LTC4-synthase gene or other leukotriene-forming enzymes are involved in the pathogenesis of the different subsets of NSAID sensitivity.     

Characterization of within-subject responses to fluticasone and montelukast in childhood asthma

BACKGROUND: Responses to inhaled corticosteroids (ICSs) and leukotriene receptor antagonists (LTRAs) vary among asthmatic patients. OBJECTIVE: We sought to determine whether responses to ICSs and LTRAs are concordant for individuals or whether asthmatic patients who do not respond to one medication respond to the other. METHODS: Children 6 to 17 years of age with mild-to-moderate persistent asthma were randomized to one of 2 crossover sequences, including 8 weeks of an ICS, fluticasone propionate (100 microg twice daily), and 8 weeks of an LTRA, montelukast (5-10 mg nightly depending on age), in a multicenter, double-masked, 18-week trial. Response was assessed on the basis of improvement in FEV 1 and assessed for relationships to baseline asthma phenotype-associated biomarkers. RESULTS: Defining response as improvement in FEV 1 of 7.5% or greater, 17% of 126 participants responded to both medications, 23% responded to fluticasone alone, 5% responded to montelukast alone, and 55% responded to neither medication. Compared with those who responded to neither medication, favorable response to fluticasone alone was associated with higher levels of exhaled nitric oxide, total eosinophil counts, levels of serum IgE, and levels of serum eosinophil cationic protein and lower levels of methacholine PC(20) and pulmonary function; favorable response to montelukast alone was associated with younger age and shorter disease duration. Greater differential response to fluticasone over montelukast was associated with higher bronchodilator use, bronchodilator response, exhaled nitric oxide levels, and eosinophil cationic protein levels and lower methacholine PC(20) and pulmonary function values. CONCLUSIONS: Response to fluticasone and montelukast vary considerably. Children with low pulmonary function or high levels of markers associated with allergic inflammation should receive ICS therapy. Other children could receive either ICSs or LTRAs.     

Association of IL-13, RANTES, and leukotriene C4 synthase gene promoter polymorphisms with asthma and/or atopy in African Americans.

PURPOSE: IL-13, RANTES (Regulated on Activation, Normal T cells Expressed and Secreted), and cysteinyl leukotrienes are asthma and atopy mediators. Two RANTES -403(G to A) and -28(C to G), an -1055 IL-13(C to T), and a -444(A to C) leukotriene C4 synthase (LTC4S) single nucleotide polymorphisms (SNPs) have been shown in Caucasians and Asians as asthma and atopy risk factors. We studied these SNPs in African Americans with asthma and/or atopy. METHODS: We studied 61 patients with asthma and/or atopy and 129 to 157 newborn controls for the -403 RANTES, -28 RANTES, and -1055 IL-13 SNPs, as well as 47 patients and 60 newborn controls for the -444 LTC4S SNP. RESULTS: The two groups did not significantly differ at the genotypes of the -403 and -28 RANTES SNP. On the other hand, the mutant TT genotype for the -1055 IL-13 SNP was detected in 19.7% of patients versus 12.7% in controls (P < 0.04, OR 2.9, 95% CI 1.0-8.0), and the mutant T allele in 58.3% versus 36.6% in controls (P < 0.02, OR 2.4, 95% CI 1.1-5.2). In a similar fashion, for the -444 LTC4S SNP, the mutant AC genotype was detected in 19.1% versus 10.0% in controls (P > 0.28); mutant C allele had an OR of 2.1 (95% CI 0.7-6.3). CONCLUSION: African American asthmatics/atopics had higher frequency of the TT mutant gene for the -1055 IL-13 SNP and of its mutant T allele. Regarding the -444 LTC4S SNP, there was a definite difference, although not statistically significant, with an OR of 2.1 for the mutant AC genotype in patients. If these findings become reproduced by larger studies, it may suggest that IL-13 and LTC4S SNPs can be used as predictive markers for asthma/atopy in African Americans.     

Montelukast, a leukotriene receptor antagonist, reduces the concentration of leukotrienes in the respiratory tract of children with persistent asthma

BACKGROUND: Leukotrienes are bronchoactive mediators secreted by inflammatory cells in the respiratory mucosa on exposure to asthma triggers. OBJECTIVE: We investigated the effect of montelukast, a leukotriene receptor antagonist, on the release of leukotrienes in the respiratory mucosa of children with persistent asthma. METHOD: Twenty-three children aged 6 to 11 years with moderately severe asthma were treated in a cross-over design starting, after a 2-week run in period, with either montelukast (n = 12) or cromolyn (n = 11) for 4 weeks with a 2-week washout period between treatments. Twelve of them were then treated with either montelukast or beclomethasone for 6 months. The use of beta(2)-agonists was recorded on a diary card. The concentration of leukotriene C(4) (LTC(4)) was measured by HPLC in nasal washes obtained before and at the end of each treatment period. Eosinophilic cationic protein (ECP) was measured in the nasal washes by RIA. RESULTS: The LTC(4) concentration significantly decreased in the children treated for the first 4 weeks with montelukast, from 5.03 +/- 1.17 to 1.42 +/- 0.33 ng/mL (P <.005), and a nonsignificant increase was noted in children treated with cromolyn, from 3.37 +/- 1.11 to 5.88 +/- 2.17 ng/mL (P =.17). ECP concentration also decreased in the children receiving montelukast (P =.12). The concentration of LTC(4) remained low after 3 and 6 months of treatment with montelukast (0.8 +/- 0.7 and 1.0 +/- 0.3 microg/mL) and was lower than with beclomethasone. Children treated with montelukast required significantly fewer beta(2)-agonists (P <.04), CONCLUSION: Montelukast reduces the concentration of leukotrienes in the respiratory tract of children with persistent asthma parallel to reduction in ECP and clinical improvement. This effect was not observed when the same children were treated with cromolyn.     

Cysteinyl leukotrienes induce human eosinophil locomotion and adhesion molecule expression via a CysLT1 receptor-mediated mechanism

BACKGROUND: The mechanisms involved in eosinophil recruitment by cysteinyl-leukotrienes (CysLTs) remain to be defined. OBJECTIVE: We investigated whether CysLTs LTC4, LTD4 and LTE4 could directly stimulate in vitro adhesion molecule expression and cell locomotion of blood eosinophils from atopic asthmatic donors. METHODS: Mab staining and FACS analysis were used to evaluate Mac-1 and LFA-1 expression on eosinophils before and after CysLTs stimulation. Eosinophil locomotion was tested using a 48-well Boyden microchamber. RESULTS: CysLTs, at the concentrations of 1 and 10 nM, were able to significantly up-regulate Mac-1 expression (P < 0.05, each comparison) but not LFA-1 expression (P > 0.05, each comparison). A dose-dependent, eosinophil chemotaxis was also induced by LTC4, LTD4 and LTE4 (0.1-10 nM) (P < 0.01, each comparison). Montelukast (0.01 nM to 10 nM), a specific CysLT1 receptor antagonist, significantly down-regulated LTC4, LTD4 and LTE4-induced Mac-1 expression (P < 0.01, each comparison) and the CysLT-induced eosinophil migration (P < 0.01, each comparison). In contrast, montelukast did not affect Mac-1 expression or cell migration when eosinophils were stimulated by the 'non-specific activators', such as fMLP or C5a (P > 0.05, each comparison). CONCLUSION: These data demonstrate that CysLTs are active in vitro in directly up-regulating human eosinophil functions involved in eosinophil recruitment. The down-regulation of Mac-1 expression and eosinophil chemotaxis by the potent and selective CysLT1 receptor antagonist montelukast indicated the specificity of the LTC4-, LTD4- and LTE4-induced response.     

Gene–gene interaction between interleukin-4 and interleukin-4 receptor α in Korean children with asthma

BACKGROUND: Interleukin-4 receptor alpha (IL-4Ralpha), which binds IL-4 and IL-13, is involved in signal transduction of those cytokines that lead to IgE production, and is also a key functional component of the Th2 lymphocyte phenotype. OBJECTIVE: To determine whether IL-4 and IL-4Ralpha polymorphisms are associated with susceptibility to asthma and whether there are gene-gene interactions between IL-4 and IL-4Ralpha polymorphisms. METHODS: We genotyped three groups of Korean children, consisting of 196 atopic asthmatics, 60 non-atopic asthmatics, and 100 healthy children, for an IL-4 promoter polymorphism (C-590T) and three IL-4Ralpha polymorphisms (Ile50Val, Pro478Ser, and Arg551Gln) using PCR-RFLP (restriction fragment length polymorphism) assays. RESULTS: The allele frequencies of the IL-4 (C/T) polymorphism and the Ile50Val and Pro478Ser polymorphisms of IL-4Ralpha did not differ statistically among the three groups of children. For the Arg551Gln polymorphism, the combined genotype frequency of the Arg/Gln heterozygote and the Arg/Arg homozygote was significantly higher in atopic asthmatics (27.6%) than in healthy children (16.0%) (odds ratio (OR) = 1.97, 95% CI (confidence interval) = 1.07-3.71). The eosinophil fraction (%) and bronchial responsiveness were higher in children with the Arg/Gln and Arg/Arg genotype than in those with the Gln/Gln genotype (P = 0.036 and 0.024, respectively). In asthmatic children, combinations of the IL-4 CT/TT genotype and the IL-4Ralpha Arg/Gln and Arg/Arg genotypes were associated with significantly increased risk for development of asthma (OR = 3.70, 95% CI = 1.07-12.78, P = 0.038). CONCLUSIONS: In Korean children, the IL-4Ralpha Arg551 allele may play a role in susceptibility to atopic asthma and correlate with markers of asthma pathogenesis, including increased eosinophil fraction and enhanced bronchial hyper-responsiveness. In addition, a significant gene-gene interaction between the IL-4-590C and the IL-4Ralpha Arg551 allele significantly increases an individual's susceptibility to asthma.     

Effects of pranlukast on aspirin-induced bronchoconstriction: differences in chemical mediators between aspirin-intolerant and tolerant asthmatic patients.

BACKGROUND: Aspirin inhibits cyclooxygenase activity and modifies production of the arachidonate cascade in aspirin-induced asthma. The aim of the present study was to examine the effects of leukotriene (LT) receptor antagonist on aspirin challenge on eosinophil activity and chemical mediators released into the airway of asthmatic patients. METHODS: Aspirin oral provocation test was performed in aspirin-intolerant asthmatic patients (AIA; N = 7) and aspirin-tolerant asthmatic patients (ATA; N = 7). In AIA, LT receptor antagonist (pranlukast) was administered orally 2 hours before the test, and its inhibitory effects on sputum LTC4+C4, eosinophil cationic protein (ECP), eosinophil count, urinary LTE4/creatinine (Cr), 11-dehydrothromboxane (11-dhTX) B2/Cr, serum LTC4+D4, ECP, and peripheral blood eosinophil count were compared with the findings in ATA subjects. RESULTS: In AIA, aspirin induced an immediate reaction associated with increased urinary LTE4/Cr and sputum ECP and a fall in urinary 11-dhTXB2/Cr. Pranlukast inhibited the bronchial reaction and an increase in sputum ECP after threshold dosed of ASA, but failed to change aspirin-induced LT production in sputum and urine. In ATA, aspirin challenge was only associated with a fall in urinary 11-dhTXB2. CONCLUSIONS: Our results indicated that aspirin-induced asthma is associated with overproduction of LT with a shift to the 5-lipoxygenase series of the arachidonate cascade and that leukotriene receptor antagonist are useful for AIA through inhibition of production of LT and eosinophilic inflammation in the airway.     

IFN-γ与 IL-4基因多态性与儿童哮喘易感性及外周血IFN-γ、IL-4和IgE的关系

目的: 探讨IFN-γ和 IL-4 基因多态性与儿童哮喘易感性及血浆IFN-γ、IL-4和IgE的相关性。方法: 用聚合酶链反应-限制性酶切片段长度多态性(PCR-RFLP)法检测100例哮喘儿童和122例对照儿童IFN-γ基因-179G/T、 IL-4 基因-33C/T和-589C/T位点基因型;等位基因特异性-聚合酶链反应(AS-PCR)法检测IFN-γ基因+874A/T位点基因型;毛细管电泳法检测IFN-γ基因CA重复序列基因型;ELISA法测定血浆IFN-γ、IL-4和IgE。结果: 100例哮喘儿童和122例对照儿童IFN-γ基因-179位点均为GG纯合子,未检测到突变基因型。IFN-γ基因+874A/T位点和CA重复序列的基因型和等位基因频率分布在哮喘组和对照组间无显著差异(P>0.05);+874位点多态性与血浆IFN-γ水平相关,AA基因型IFN-γ含量低于AT基因型(P<0.05)。 IL-4 基因-33C/T和-589C/T位点的基因型和等位基因频率分布在哮喘组和对照组间有显著差异(P<0.05);-33和-589位点TT基因型外周血IL-4和总IgE浓度均高于CT基因型,只有-33位点与血浆IL-4水平存在相关性(P<0.05)。结论: IFN-γ基因+874A/T和CA重复序列多态性可能与儿童哮喘无相关性,+874A/T位点多态性与IFN-γ水平相关。 IL-4 基因-33TT和-589TT基因型可能为儿童哮喘的易感基因型,-33位点多态性与IL-4表达水平相关。     

Leukotriene C4 synthase promoter polymorphism in Japanese patients with aspirin-induced asthma

BACKGROUND: The A to C transversion in the promoter region of the gene encoding leukotriene C4 synthase (LTC4S) is proposed to be associated with the development of aspirin-induced asthma (AIA). OBJECTIVE: We investigated the frequency of the polymorphism in Japanese population and its association with clinical characteristics and cysteinyl leukotriene production. METHODS: Genotyping of LTC4S gene promoter was performed on 60 patients with AIA, 100 patients with aspirin-tolerant asthma (ATA), and 110 control subjects. We assessed the basal levels of urinary LTE4, the increment of urinary LTE4 on venous aspirin challenge, and LTC4S activity in peripheral blood eosinophils. RESULTS: The frequency of the variant C allele was significantly higher in patients with AIA (frequency of allele [q] = 0.192) than in patients with ATA (q = 0.110, P =.042). Variant C-allelic carriers experienced asthma at a significantly younger age (31.8 +/- 2.9 years [mean +/- SEM]) than wild-type A homozygotes (41.3 +/- 2.2 years, P =.007). Basal levels of LTE4 and the increment of urinary LTE4 on venous aspirin challenge did not show a difference between wild-type A homozygotes and variant C-allelic carriers. There was no relationship between the polymorphism and the LTC4S activity in eosinophils, although LTC4S activities were significantly higher in patients with AIA than in patients with ATA. CONCLUSION: Our findings reveal the lack of functionality of the polymorphism in the LTC4S gene, whereas this polymorphism might have some effect on the development of AIA, probably in linkage disequilibrium with another causatively important mutation.     

Inhibition of leukotriene C4 and B4 generation by human eosinophils and neutrophils with the lipoxygenase pathway inhibitors U60257 and BW755C

Human eosinophils and neutrophils have the capacity to generate leukotriene C4 (LTC4) and leukotriene B4 (LTB4) respectively when stimulated by calcium ionophore A23187. Leukotriene production by mixtures of these cell types was measured by radioimmunoassay for LTC4 and LTB4, and the specificities of the assays determined by assessing cross-reactivities with a number of other arachidonic acid metabolites. The IC50S for LTC4 and LTB4 in their respective assays were 1.76 +/- 0.04 nmol and 3.00 +/- 0.08 nmol. Cross-reactivity for anti-LTC4 was shown by leukotriene D4 (LTD4) (70%) and leukotriene E4 (LTE4) (8%), when compared to LTC4, whereas in the radioimmunoassay for LTB4, only the 5(S), 12(R) 6-trans isomer of LTB4 showed appreciable interaction (12%). LTC4 production by eosinophil enriched cell fractions obtained from metrizamide gradients was inhibited in a dose-dependent fashion by the prostacyclin analogue, 6,9-deepoxy-6,9-phenylimino-delta 6,8-prostaglandin I, (U60257) and by 3-amino-1-(3-trifluoromethyl phenyl)-2-pyrazole (BW755C). The ID50 values for U60257 and BW755C were 2 X 10(-6) and 5 X 10(-6) M respectively. This demonstration of LTC4 production by human eosinophils, which are known to be important cells in clinical asthma, provides an in vitro model to assess 5-lipoxygenase inhibitors in human tissue.     

A randomized, double-blind trial of the effect of treatment with montelukast on bronchial hyperresponsiveness and serum eosinophilic cationic protein (ECP), soluble interleukin 2 receptor (sIL-2R), IL-4, and soluble intercellular adhesion molecule 1 (sICAM-1) in children with asthma

BACKGROUND: Anti-inflammatory properties of leukotriene modifiers and their effect on bronchial hyperresponsiveness have not been studied in children with asthma. OBJECTIVE: The primary objective of this study was to determine the changes in serum levels of inflammatory mediators, clinical efficacy, and bronchial hyperresponsiveness after treatment with montelukast. METHODS: In this double-blind, randomized, placebo-controlled trial, 39 children with mild-to-moderate atopic asthma were randomly allocated to receive montelukast or placebo for 6 weeks. Main outcome measures were changes in serum concentrations of soluble interleukin 2 receptor (sIL-2R), IL-4, and soluble intercellular adhesion molecule 1 (sICAM-1); peripheral blood eosinophil count; and eosinophilic cationic protein (ECP). Asthma severity score, FEV(1), and bronchial hyperreactivity (BHR) for histamine were secondary end points. RESULTS: Compared to placebo, serum concentrations of IL-4, sICAM-1, and ECP and eosinophil blood counts significantly decreased after 6 weeks of treatment with montelukast. Montelukast significantly improved asthma control and FEV(1). Montelukast resulted in within-group significant decrease in levels of serum sIL-2R (611 vs. 483 pg/mL), IL-4 (0.123 vs 0.102 pg/mL), sICAM-1 (280 vs. 244 ng/mL), and ECP (74 vs. 59 microg/mL) and in eosinophil blood counts (349 vs. 310 cells/mm(3)). Mean FEV(1) value changed from 85% of predicted to 95% (P <.001) and for histamine (PC(20)H) from 2.8 mg/mL to 3.8 mg/mL (P <.001) after treatment with montelukast. There was no significant difference between montelukast and placebo recipients in the serum concentrations of sIL-2R and PC(20)H after treatment. CONCLUSION: Montelukast provides clinical benefit to patients with chronic asthma and decreases bronchial hyperresponsiveness. Montelukast caused a statistically significant decrease of serum concentrations in cytokine, ICAM-1, and ECP and peripheral blood eosinophil counts over the 6-week treatment period. This observation raises the possibility that leukotriene receptor antagonists, such as montelukast, may have effects on parameters of asthmatic inflammation.     

Enhanced leukotriene C4 production by peripheral eosinophilic granulocytes from children with asthma

Granulocytes and mononuclear cells were isolated from the blood of asthmatic and healthy children. Stimulation with ionophore A 23187 induced a significantly higher leukotriene C4 (LTC4) generation from granulocytes of asthmatic children than from granulocytes of healthy controls. In contrast, mononuclear cells from patients and controls did not differ in their ability to produce LTC4. Additional analysis showed that the difference in LTC4 generation of granulocytes was due to increased formation but not to decreased oxidative degradation of LTC4. Analysis of LTC4 generation of purified neutrophils and eosinophils revealed that LTC4 was generated almost exclusively by eosinophils and, in particular, the hypodense population. Granulocytes from patients with a history of severe asthma displayed a higher LTC4 formation than granulocytes from patients with less severe disease.