Effects of pranlukast on chemical mediators in induced sputum on provocation tests in atopic and aspirin-intolerant asthmatic patients

Urinary Leukotriene E4 as a Biomarker in NSAID-Exacerbated Respiratory Disease (N-ERD): a Systematic Review and Meta-analysis

PURPOSE OF REVIEW

Non-steroidal exacerbated respiratory disease (N-ERD) currently requires aspirin challenge testing for diagnosis. Urinary leukotriene E4 (uLTE₄) has been extensively investigated as potential biomarker in N-ERD. We aimed to assess the usefulness of uLTE₄ as a biomarker in the diagnosis of N-ERD.

RECENT FINDINGS

N-ERD, formerly known as aspirin-intolerant asthma (AIA), is characterised by increased leukotriene production. uLTE₄ indicates cysteinyl leukotriene production, and a potential biomarker in N-ERD. Although several studies and have examined the relationship between uLTE₄ and N-ERD, the usefulness of uLTE₄ as a biomarker in a clinical setting remains unclear.

FINDINGS

Our literature search identified 38 unique eligible studies, 35 were included in the meta-analysis. Meta-analysis was performed (i.e. pooled standardised mean difference (SMD) with 95% confidence intervals (95% CI)) and risk of bias assessed (implementing Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy (Cochrane DTA)). Data from 3376 subjects was analysed (1354 N-ERD, 1420 ATA, and 602 HC). uLTE₄ was higher in N-ERD vs ATA (n = 35, SMD 0.80; 95% CI 0.72-0.89). uLTE4 increased following aspirin challenge in N-ERD (n = 12, SMD 0.56; 95% CI 0.26-0.85) but not ATA (n = 8, SMD 0.12; CI - 0.08-0.33). This systematic review and meta-analysis showed that uLTE₄ is higher in N-ERD than ATA or HC. Likewise, people with N-ERD have greater increases in uLTE₄ following aspirin challenge. However, due to the varied uLTE₄ measurement and result reporting practice, clinical utility of these findings is limited. Future studies should be standardised to increase clinical significance and interpretability of the results.

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.

G Protein-Coupled Receptors in Asthma Therapy: Pharmacology and Drug Action

Asthma is a heterogeneous inflammatory disease of the airways that is associated with airway hyperresponsiveness and airflow limitation. Although asthma was once simply categorized as atopic or nonatopic, emerging analyses over the last few decades have revealed a variety of asthma endotypes that are attributed to numerous pathophysiological mechanisms. The classification of asthma by endotype is primarily routed in different profiles of airway inflammation that contribute to bronchoconstriction. Many asthma therapeutics target G protein-coupled receptors (GPCRs), which either enhance bronchodilation or prevent bronchoconstriction. Short-acting and long-acting β 2-agonists are widely used bronchodilators that signal through the activation of the β 2-adrenergic receptor. Short-acting and long-acting antagonists of muscarinic acetylcholine receptors are used to reduce bronchoconstriction by blocking the action of acetylcholine. Leukotriene antagonists that block the signaling of cysteinyl leukotriene receptor 1 are used as an add-on therapy to reduce bronchoconstriction and inflammation induced by cysteinyl leukotrienes. A number of GPCR-targeting asthma drug candidates are also in different stages of development. Among them, antagonists of prostaglandin D2 receptor 2 have advanced into phase III clinical trials. Others, including antagonists of the adenosine A2B receptor and the histamine H4 receptor, are in early stages of clinical investigation. In the past decade, significant research advancements in pharmacology, cell biology, structural biology, and molecular physiology have greatly deepened our understanding of the therapeutic roles of GPCRs in asthma and drug action on these GPCRs. This review summarizes our current understanding of GPCR signaling and pharmacology in the context of asthma treatment. SIGNIFICANCE STATEMENT: Although current treatment methods for asthma are effective for a majority of asthma patients, there are still a large number of patients with poorly controlled asthma who may experience asthma exacerbations. This review summarizes current asthma treatment methods and our understanding of signaling and pharmacology of G protein-coupled receptors (GPCRs) in asthma therapy, and discusses controversies regarding the use of GPCR drugs and new opportunities in developing GPCR-targeting therapeutics for the treatment of asthma.

Current state and future prospect of the therapeutic strategy targeting cysteinyl leukotriene metabolism in asthma

Asthma is an allergic disorder with dominant type 2 airway inflammation, and its prevalence is increasing worldwide. Inhalation of corticosteroids is the primary treatment for asthma along with add-on drugs, including long-acting β2 agonists and/or cysteinyl leukotriene (cys-LT) receptor antagonists, in patients with poorly controlled asthma. Cys-LTs are composed of leukotriene C4 (LTC₄), LTD₄, and LTE₄, which are enzymatically metabolized from arachidonic acid. These molecules act as inflammatory mediators through different types of high-affinity receptors, namely, CysLT₁, CysLT₂, and CysLT₃ (also named as GPR99). CysLT₁ antagonists possessing anti-inflammatory and bronchodilatory effects can be orally administered to patients with asthma. Recently, molecular biology-based studies have revealed the mechanism of inflammatory responses via other receptors, such as CysLT₂ and CysLT₃, as well as the importance of upstream inflammatory regulators, including type 2 cytokines (e.g., interleukins 4 and 5), in controlling cys-LT metabolism. These findings indicate the therapeutic potential of pharmacological agents targeting cys-LT metabolism-related receptors and enzymes, and antibody drugs neutralizing or antagonizing type 2 cytokines. This review focuses on the current state and future prospect of the therapeutic strategy targeting cys-LT metabolism.

NSAID-induced reactions: classification, prevalence, impact, and management strategies

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the leading cause of hypersensitivity drug reactions. The different chemical structures, cyclooxygenase 1 (COX-1) and/or COX-2 inhibitors, are taken at all ages and some can be easily obtained over the counter. Vasoactive inflammatory mediators like histamine and leukotriene metabolites can produce local/systemic effects. Responders can be selective (SR), IgE or T-cell mediated, or cross-intolerant (CI). Inhibition of the COX pathway is the common mechanism in CI, with the skin being the most frequent organ involved, followed by the lung and/or the nose. An important number of cases have skin and respiratory involvement, with systemic manifestations ranging from mild to severe anaphylaxis. Among SR, this is the most frequent entity, often being severe. Recent years have seen an increase in reactions involving the skin, with many cases having urticaria and/or angioedema in the absence of chronic urticaria. Aspirin, the classical drug involved, has now been replaced by other NSAIDs, with ibuprofen being the universal culprit. For CI, no in vivo/in vitro diagnostic methods exist and controlled administration is the only option unless the cases evaluated report repetitive and consistent episodes with different NSAIDs. In SR, skin testing (patch and intradermal) with 24-48 reading can be useful, mainly for delayed T-cell responses. Acetyl salicylic acid (ASA) is the test drug to establish the diagnosis and confirm/exclude CI by controlled administration. Desensitization to ASA has been extensively used in respiratory cases though it can also be applied in those cases where it is required.

Diagnosis and management of NSAID-Exacerbated Respiratory Disease (N-ERD)-a EAACI position paper

NSAID-exacerbated respiratory disease (N-ERD) is a chronic eosinophilic, inflammatory disorder of the respiratory tract occurring in patients with asthma and/or chronic rhinosinusitis with nasal polyps (CRSwNP), symptoms of which are exacerbated by NSAIDs, including aspirin. Despite some progress in understanding of the pathophysiology of the syndrome, which affects 1/10 of patients with asthma and rhinosinusitis, it remains a diagnostic and therapeutic challenge. In order to provide evidence-based recommendations for the diagnosis and management of N-ERD, a panel of international experts was called by the EAACI Asthma Section. The document summarizes current knowledge on the pathophysiology and clinical presentation of N-ERD pointing at significant heterogeneity of this syndrome. Critically evaluating the usefulness of diagnostic tools available, the paper offers practical algorithm for the diagnosis of N-ERD. Recommendations for the most effective management of a patient with N-ERD stressing the potential high morbidity and severity of the underlying asthma and rhinosinusitis are discussed and proposed. Newly described sub-phenotypes and emerging sub-endotypes of N-ERD are potentially relevant for new and more specific (eg, biological) treatment modalities. Finally, the document defines major gaps in our knowledge on N-ERD and unmet needs, which should be addressed in the future.

Montelukast Reduces Serum Levels of Eosinophil-Derived Neurotoxin in Preschool Asthma

PURPOSE

Several markers for eosinophilic inflammation have been proposed to predict response to asthma treatment. However, definitive criteria for treatment decisions have not yet been established. We investigate a potentially useful relatively non-invasive biomarker, eosinophil-derived neurotoxin (EDN), to predict favorable responses to budesonide or montelukast, common treatment for children with asthma.

METHODS

Young children (1 to 6 years old) were enrolled in this randomized, parallel, 2-group, open-label trial. Criteria for eligibility included: 1) being symptomatic during the run-in period; and 2) having a serum EDN (sEDN) level ≥ 53 ng/mL, with positive specific immunoglobulin E to house dust mite. Eligible patients were randomly placed into 2 groups: the BIS group received budesonide inhalation suspension (BIS) 0.5 mg once daily; the MONT group received montelukast 4 mg once daily. Ineligible patients were invited to receive montelukast 4 mg once daily (OBS group). Treatment period was 12 weeks.

RESULTS

Asthma control days increased significantly in the BIS and MONT groups (P < 0.000) over the 12-week study period. There was no significant change in sEDN in the BIS group but there was a significant decrease in the MONT group (P < 0.000). Patients in the OBS group with high EDN levels (< 53 ng/mL) showed a significant decrease due to MONT treatment (P = 0.023). Rescue medication usage significantly decreased in the BIS and MONT groups (P < 0.000).

CONCLUSIONS

EDN is a useful relatively non-invasive biomarker for predicting responses to montelukast and budesonide treatment of preschool children with beta2-agonist responsive recurrent wheeze and multiple-trigger wheeze (Trial registry at UMIN Clinical Trials Registry, UMIN000008335).

Involvement and Possible Role of Eosinophils in Asthma Exacerbation

Eosinophils are involved in the development of asthma exacerbation. Recent studies have suggested that sputum and blood eosinophil counts are important factors for predicting asthma exacerbation. In severe eosinophilic asthma, anti-interleukin (IL)-5 monoclonal antibody decreases blood eosinophil count and asthma exacerbation frequency. However, even in the absence of IL-5, eosinophilic airway inflammation can be sufficiently maintained by the T helper (Th) 2 network, which comprises a cascade of vascular cell adhesion molecule-1/CC chemokines/eosinophil growth factors, including granulocyte-macrophage colony-stimulating factor (GM-CSF). Periostin, an extracellular matrix protein and a biomarker of the Th2 immune response in asthma, directly activates eosinophils in vitro. A major cause of asthma exacerbation is viral infection, especially rhinovirus (RV) infection. The expression of intercellular adhesion molecule (ICAM)-1, a cellular receptor for the majority of RVs, on epithelial cells is increased after RV infection, and adhesion of eosinophils to ICAM-1 can upregulate the functions of eosinophils. The expressions of cysteinyl leukotrienes (cysLTs) and CXCL10 are upregulated in virus-induced asthma. CysLTs can directly provoke eosinophilic infiltration in vivo and activate eosinophils in vitro. Furthermore, eosinophils express the CXC chemokine receptor 3, and CXCL10 activates eosinophils in vitro. Both eosinophils and neutrophils contribute to the development of severe asthma or asthma exacerbation. IL-8, which is an important chemoattractant for neutrophils, is upregulated in some cases of severe asthma. Lipopolysaccharide (LPS), which induces IL-8 from epithelial cells, is also increased in the lower airways of corticosteroid-resistant asthma. IL-8 or LPS-stimulated neutrophils increase the transbasement membrane migration of eosinophils, even in the absence of chemoattractants for eosinophils. Therefore, eosinophils are likely to contribute to the development of asthma exacerbation through several mechanisms, including activation by Th2 cytokines, such as IL-5 or GM-CSF or by virus infection-related proteins, such as CXCL10, and interaction with other cells, such as neutrophils.

House Dust Mite Respiratory Allergy: An Overview of Current Therapeutic Strategies

Although house dust mite (HDM) allergy is a major cause of respiratory allergic disease, specific diagnosis and effective treatment both present unresolved challenges. Guidelines for the treatment of allergic rhinitis and asthma are well supported in the literature, but specific evidence on the efficacy of pharmacotherapy treatment for known HDM-allergic patients is weaker. The standard diagnostic techniques--skin prick test and specific IgE testing--can be confounded by cross-reactivity. However, component-resolved diagnosis using purified and recombinant allergens can improve the accuracy of specific IgE testing, but availability is limited. Treatment options for HDM allergy are limited and include HDM avoidance, which is widely recommended as a strategy, although evidence for its efficacy is variable. Clinical efficacy of pharmacotherapy is well documented; however, symptom relief does not extend beyond the end of treatment. Finally, allergen immunotherapy has a poor but improving evidence base (notably on sublingual tablets) and its benefits last after treatment ends. This review identifies needs for deeper physician knowledge on the extent and impact of HDM allergy in respiratory disease, as well as further development and improved access to molecular allergy diagnosis. Furthermore, there is a need for the development of better-designed clinical trials to explore the utility of allergen-specific approaches, and uptake of data into guidance for physicians on more effective diagnosis and therapy of HDM respiratory allergy in practice.

Enhanced cysteinyl-leukotriene type 1 receptor expression in T cells from house dust mite-allergic individuals following stimulation with Der p

In order to determine the potential for allergen to modulate T cell expression of the CysLT₁ receptor and responsiveness to leukotrienes, peripheral blood mononuclear cells from house dust mite-allergic or nonallergic individuals were incubated with D. pteronyssinus allergen (Der p). Baseline CysLT₁ expression was similar in both groups of donors, but Der p significantly enhanced CysLT₁ expression in CD4⁺ and CD8⁺ T cells of only allergic individuals and induced enhanced responsiveness of CD4⁺ T cells to LTD₄ in terms of calcium mobilisation. This effect was prevented by the CysLT₁ antagonist MK571. Der p also induced IL-4 and IL-10 production, and neutralizing antibody to IL-4 prevented both the enhanced CysLT₁ expression and the enhanced responsiveness of T cells to LTD₄ induced by Der p. In allergic individuals, Der p also induced T cell proliferation and a Th2-biased phenotype. Our data suggest that, in allergen-sensitized individuals, exposure to allergen can enhance T cell expression of CysLT₁ receptors through a mechanism involving IL-4 production. This, in turn, would induce CD4⁺ T cell responsiveness to cysteinyl-leukotrienes and Th2 cell activation.

Induced sputum eicosanoids during aspirin bronchial challenge of asthmatic patients with aspirin hypersensitivity

BACKGROUND

Altered metabolism of eicosanoids is a characteristic finding in aspirin-exacerbated respiratory disease (AERD). Bronchial challenge with lysyl-aspirin can be used as a confirmatory diagnostic test for this clinical condition. Induced sputum allows to measure mediators of asthmatic inflammation in bronchial secretions.

OBJECTIVES

To investigate the influence of inhaled lysyl-aspirin on sputum supernatant concentration of eicosanoids during the bronchial challenge test. Subjects with asthma hypersensitive to nonsteroidal anti-inflammatory drugs were compared with aspirin-tolerant asthmatic controls.

METHODS

Induced sputum was collected before and following bronchial challenge with lysyl-aspirin. Sputum differential cell count and sputum supernatant concentrations of selected lipoxygenases products: 5-,12-,15-hydroxyeicosatetraenoic acid, cysteinyl leukotrienes, leukotriene B4 , 11-dehydro-thromboxane B2 , and prostaglandins E2 , D2 , and F2α and their metabolites, were measured using validated methods of chromatography-mass spectrometry.

RESULTS

Aspirin precipitated bronchoconstriction in all AERD subjects, but in none of the aspirin-tolerant asthmatics. Phenotypes of asthma based on the sputum cytology did not differ between the groups. Baseline sputum eosinophilia correlated with a higher leukotriene D4 (LTD4 ) and leukotriene E4 (LTE4 ) concentrations. LTC4 , PGE2 , and 11-dehydro-TXB2 did not differ between the groups, but levels of LTD4 , LTE4 , and PGD2 were significantly higher in AERD group. Following the challenge, LTD4 and LTE4 increased, while PGE2 and LTB4 decreased in AERD subjects only.

CONCLUSIONS

During the bronchial challenge, decrease in PGE2 and its metabolite is accompanied by a surge in bronchoconstrictory cysteinyl leukotrienes produced at the expense of LTB4 in AERD subjects. Bronchial PGE2 inhibition in AERD seems specific and sensitive to a low dose of aspirin.

Retrospective cohort study of leukotriene receptor antagonist therapy for preventing upper respiratory infection-induced acute asthma exacerbations

Upper respiratory tract infections (URIs) represent the most frequent cause of acute asthma exacerbations. It has yet to be determined whether leukotriene receptor antagonist (LTRA) treatment prevents URI-induced acute asthma exacerbations in adults. The objective of the present study was to evaluate the preventive effects of LTRA treatment on URI-induced acute asthma exacerbations. The incidences of URI alone, acute asthma exacerbation without URI, and URI-induced acute asthma exacerbation were determined retrospectively by analyzing diary and medical records of 321 adult asthmatic patients (mean age, 56.3 ± 17.2 years; male/female ratio, 117:204) over 1 year. Results were compared between patients who had been taking an LTRA (n = 137) and those who had never taken any LTRA (n = 184) during the study periods. Significantly fewer URIs alone and acute asthma exacerbations without URI occurred in patients with than in those without prophylactic daily use of LTRA. LTRA treatment significantly reduced the durations of URIs alone and of total acute asthma exacerbations, as well as the incidence of mild exacerbations of asthma. In contrast, in patients with URI-induced acute asthma exacerbations, LTRA treatment failed to significantly reduce the interval between URI onset and acute asthma exacerbation, as well as the duration and severity of both URIs and acute asthma exacerbations. Use of an LTRA for adult asthmatic patients appears to reduce the incidences of URIs alone and acute asthma exacerbations without URI, but it failed to prevent URI-induced acute asthma exacerbations once a URI occurred.

Leukotriene receptor antagonists pranlukast and montelukast for treating asthma

INTRODUCTION

The prevalence of bronchial asthma, which is a chronic inflammatory disorder of the airway, is increasing worldwide. Although inhaled corticosteroids (ICS) play a central role in the treatment of asthma, they cannot achieve good control for all asthmatics, and medications such as leukotriene receptor antagonists (LTRAs) with bronchodilatory and anti-inflammatory effects often serve as alternatives or add-on drugs.

AREAS COVERED

Clinical trials as well as basic studies of montelukast and pranlukast in animal models are ongoing. This review report clarifies the current status of these two LTRAs in the treatment of asthma and their future direction.

EXPERT OPINION

LTRAs could replace ICS as first-line medications for asthmatics who are refractory to ICS or cannot use inhalant devices. Further, LTRAs are recommended for asthmatics under specific circumstances that are closely associated with cysteinyl leukotrienes (cysLTs). Considering the low incidence of both severe adverse effects and the induction of tachyphylaxis, oral LTRAs should be more carefully considered for treating asthma in the clinical environment. Several issues such as predicted responses, effects of peripheral airway and airway remodeling and alternative administration routes remain to be clarified before LTRAs could serve a more effective role in the treatment of asthma.

Quantitation of leukotriene B(4) in human sputum as a biomarker using UPLC-MS/MS

Leukotriene B4 (LTB4) is a potent mediator of inflammation and has been recognized as an important target for therapeutic intervention for treatment of diseases such as asthma. In the current work, a highly selective and sensitive UPLC-MS/MS assay was developed for quantitation of LTB4 in human sputum as a biomarker for LTB4 biosynthesis inhibition. A fit-for-purpose strategy for method development, assay qualification, and study support was adopted for this biomarker project. A surrogate matrix (protein buffer) was used for preparation of calibration samples and certain levels of quality control (QC) samples to avoid interference from endogenous analyte, while the low QC was prepared in authentic matrix, human sputum. The analytical methodology utilized a liquid-liquid extraction procedure in 96-well plate format. Chromatographic separation was achieved with a reversed-phase ultra high pressure liquid chromatography (UPLC) column using gradient elution, and the run time was 4.5min per sample. The lower limit of quantitation (LLOQ) was 0.2ng/mL, and the calibration curve range was 0.2-20ng/mL. Acceptable accuracy, precision, linearity, specificity, recovery, and matrix effect was obtained. Bench-top stability (6h), freeze-thaw stability (3 cycles at -20°C), and autosampler stability (97h at ambient temperature) all met acceptance criteria. Frozen long-term stability for 166 days at -20°C in sputum did not meet acceptance criteria by showing only ≥75% of nominal concentration and the information was taken into consideration for study support. Two important observations in the current work were: (1) LTB4 was unstable in sputum in the presence of liquification reagent dithiothreitol (DTT). Therefore, a non-DTT treatment method for sputum processing was developed and applied to the bioanalytical assay and clinical study support; and (2) chromatographic separation of LTB4 from its three non-enzymatically derived isomers, i.e. 6-trans-LTB4, 12-epi-LTB4, and 6-trans-12-epi-LTB4, was achieved. This assay was successfully applied to a Phase II clinical study for proof-of-concept of a LTA4 hydrolase inhibitor for treatment of asthma.

Aspirin sensitivity and chronic rhinosinusitis with polyps: a fatal combination

Aspirin-exacerbated respiratory disease (AERD) refers to aspirin sensitivity, chronic rhinosinusitis (CRS), nasal polyposis, asthma, eosinophil inflammation in the upper and lower airways, urticaria, angioedema, and anaphylaxis following the ingestion of NSAIDs. Epidemiologic and pathophysiological links between these diseases are established. The precise pathogenesis remains less defined, even though there is some progress in the understanding of several molecular mechanisms. Nevertheless, these combinations of diseases in patients classified by AERD constitute a fatal combination and may be difficult to treat with standard medical and surgical interventions. This paper reviews in brief the epidemiology, clinical features, diagnosis, molecular pathogenesis, and specific therapies of patients classified by AERD and postulates future attempts to gain new insights into this disease.

Association analysis of thromboxane A synthase 1 gene polymorphisms with aspirin intolerance in asthmatic patients

AIM

Thromboxane A synthase (TBXAS1) converts prostaglandin H to thromboxane A, a potent constrictor of smooth respiratory muscle. Thus, functional alterations of the TBXAS1 gene may contribute to aspirin-intolerant asthma (AIA).

MATERIALS & METHODS

We investigated the relationship between SNPs in the TBXAS1 gene and AIA. Asthmatics (n = 470) were categorized into AIA (20% or greater decreases in forced expiratory volume in 1 s [FEV(1)], or 15% to 19% decreases in FEV(1) with naso-ocular or cutaneous reactions) and aspirin-tolerant asthma (ATA). A total of 101 SNPs were genotyped. mRNA expression of the TBXAS1 gene by peripheral blood mononuclear cells and plasma thromboxane B2 (TXB2) concentrations were measured by reverse transcriptase (RT)-PCR and ELISA.

RESULTS

Logistic regression analysis showed that the rare allele frequency of rs6962291 in intron 9 was significantly lower in the AIA group (n = 115) than in the ATA group (n = 270) (p(corr) = 0.04). The linear regression analysis revealed a strong association of rs6962291 with the aspirin challenge-induced FEV(1) fall (p = 0.003). RT-PCR revealed an exon-12-deleted splice variant. We measured TBXAS1 mRNA levels in peripheral blood mononuclear cells. The mRNA levels of the full-length wild-type and splice variant were significantly higher in the TT homozygotes than in the AA homozygotes of rs6962291 (1.00 ± 0.18 vs 0.57 ± 0.03 and 1.00 ± 0.18 vs 0.21 ± 0.05, p = 0.047 and 0.001, respectively). The plasma TXB2 level was significantly lower in rs6962291 AA carriers than in rs6962291 TT (p = 0.016) carriers.

CONCLUSION

The rare allele of rs6962291 may play a protective role against aspirin hypersensitivity via a lower catalytic activity of the TBXAS1 gene, attributed to the increase of a nonfunctioning isoform of TBXAS1.

Increase in salivary cysteinyl-leukotriene concentration in patients with aspirin-intolerant asthma

BACKGROUND

Cysteinyl-leukotrienes (CysLTs; LTC4, LTD4, and LTE4) play a considerable role in the pathophysiology of aspirin-intolerant asthma (AIA). Saliva has recently been validated as novel, simple, and noninvasive method for investigating inflammation in patients with asthma. The aim of this study is to clarify the molecular species of CysLT in saliva and to evaluate the CysLT and LTB4 concentrations in saliva in AIA patients. We also examined how the CysLT concentration in saliva reflects that of their corresponding urinary metabolite.

METHODS

We preformed an analytical cross-sectional study. CysLT and LTB4 concentrations in saliva were quantified by enzyme immunoassay (EIA) following purification by high-performance liquid chromatography (HPLC).

RESULTS

1. When analyzed by EIA in combination with HPLC, saliva was found to consist of LTC4, LTD4 and LTE4 in similar amounts. 2. In saliva analysis among the three groups (AIA patients, aspirin-tolerant asthma [ATA] patients, and healthy subjects), both the concentrations of CysLTs and LTB4 were significantly higher in AIA patients than in ATA patients and healthy subjects. 3. We found significant correlations between CysLT concentration and LTB4 concentration in saliva in each group. 4. No significant correlation was found between the concentration of LTE4 in urine and that of CysLTs in saliva.

CONCLUSIONS

In this study, we found higher concentrations of CysLTs and LTB4 in saliva from AIA patients than in saliva from ATA patients, suggesting that the quantification of CysLT and LTB4 concentrations in saliva may be another diagnostic strategy for AIA.

KIF3A, a cilia structural gene on chromosome 5q31, and its polymorphisms show an association with aspirin hypersensitivity in asthma

INTRODUCTION

The kinesin family number 3A (KIF3A) gene on the human chromosomal 5q31-33 region, which is known as a susceptibility locus for immune diseases including asthma, plays a crucial role in generation of cilia.

RESULTS

A treatment with aspirin in the human bronchial epithelial cells increased the mRNA expression level of KIF3A compared to that of the untreated control (P ≤ 0.01), and nasal polyp epithelia from aspirin-intolerant asthma (AIA) patients also showed a higher expression of KIF3A protein than aspirin-tolerant asthma controls. Further logistic analyses revealed that most polymorphisms of KIF3A were significantly associated with AIA (P = 0.0004-0.02; P(corr) = 0.004-0.04) and the decline of forced expiratory volume at 1 s (FEV(1))% by aspirin provocation (P = 0.004-0.04; P(corr) = 0.03).

DISCUSSION

Our findings suggest that the KIF3A gene and/or its polymorphisms might have a susceptibility effect on AIA, providing a new step toward controlling aspirin intolerance in asthmatics.

A randomized intervention of montelukast for post-bronchiolitis: effect on eosinophil degranulation

OBJECTIVE

To investigate the effect of montelukast on eosinophil degranulation and recurrent wheezing episodes in post-respiratory syncytial virus (RSV) bronchiolitis.

STUDY DESIGN

Two hundred infants (age, 6-24 months) who were hospitalized with their first episode of acute RSV bronchiolitis were randomized in a double-blind, placebo-controlled, parallel comparison of 4-mg montelukast granules (RSV-MONT group) or matching placebo (RSV-PLC group) administered for 3 months. Serum eosinophil-derived neurotoxin (EDN) levels were measured (primary outcome), and recurrent wheezing was documented (secondary outcome) for 12 months. Comparisons were made with control subjects (control group, n = 50).

RESULTS

At the end of the 3-month treatment period, the RSV-PLC group (n = 71) exhibited significantly elevated EDN levels (P < .0001), and the RSV-MONT group (n = 79) showed significantly decreased EDN levels (P < .01) when compared with the initial levels. As a result, EDN levels in the 2 RSV groups significantly differed at this point (P < .0001) and remained different for the entire 12-month follow-up period. Cumulative recurrent wheezing episodes at 12 months were significantly lower in the RSV-MONT group (P = .039).

CONCLUSION

Montelukast treatment reduces eosinophil degranulation and is associated with a decrease in recurrent wheezing episodes in post-RSV bronchiolitis.

Update on recent advances in the management of aspirin exacerbated respiratory disease

Aspirin intolerant asthma (AIA) is frequently characterized as an aspirin (ASA)-exacerbated respiratory disease (AERD). It is a clinical syndrome associated with chronic severe inflammation in the upper and lower airways resulting in chronic rhinitis, sinusitis, recurrent polyposis, and asthma. AERD generally develops secondary to abnormalities in inflammatory mediators and arachidonic acid biosynthesis expression. Upper and lower airway eosinophil infiltration is a key feature of AERD; however, the exact mechanisms of such chronic eosinophilic inflammation are not fully understood. Cysteinyl leukotriene over-production may be a key factor in the induction of eosinophilic activation. Genetic studies have suggested a role for variability of genes in disease susceptibility and response to medication. Potential genetic biomarkers contributing to the AERD phenotype include HLA-DPB1*301, LTC4S, ALOX5, CYSLT, PGE2, TBXA2R, TBX21, MS4A2, IL10 -1082A > G, ACE -262A > T, and CRTH2 -466T > C; the four-locus SNP set was composed of B2ADR 46A > G, CCR3 -520T > G, CysLTR1 -634C > T, and FCER1B -109T > C. Management of AERD is an important issue. Aspirin ingestion may result in significant morbidity and mortality, and patients must be advised regarding aspirin risk. Leukotriene receptor antagonists (LTRA) that inhibit leukotriene pathways have an established role in long-term AERD management and rhinosinusitis. Aspirin desensitization may be required for the relief of upper and lower airway symptoms in AERD patients. Future research should focus on identification of biomarkers for a comprehensive diagnostic approach.

CysLTR1 promoter polymorphism and requirement for leukotriene receptor antagonist in aspirin-intolerant asthma patients

OBJECTIVES

Leukotriene receptor antagonists (LTRA), such as montelukast, have been used as a first-line treatment for patients with aspirin-intolerant asthma (AIA). This study evaluated associations between the clinical requirement for LTRA and genetic polymorphisms of the ALOX5, LTC4S, COX-2, CysLTR1 and TBXA2R genes in the arachidonic acid cascade in the long-term management of 89 AIA patients from a Korean population.

METHODS

Asthma control status was monitored for 1 year with maintenance medications of inhaled corticosteroid and oral LTRA, and AIA patients were classified into three groups according to the mean montelukast dose required per month to maintain asthma control for 1 year: group I (> or = 200 mg montelukast/month; n = 37), group II (5-150 mg/month; n = 25) and group III (< 5 mg/month; n = 27). Genetic polymorphisms in the arachidonic acid cascade were determined using a single-base extension method.

RESULTS

We found that there was a significant difference in the genotype frequency of the CysLTR1 promoter polymorphism -634C > T among the three groups (p = 0.007 for group I vs group II, p = 0.017 for group I vs group III), while there were no significant associations between LTRA requirements and polymorphisms of the other genes. The patients with the variant genotype (CT or TT) of the -634C = T CysLTR1 promoter polymorphism showed a higher expression level than those with the common genotype (CC).

CONCLUSION

These findings indicate that the CysLTR1 promoter polymorphism is a useful genetic marker for predicting LTRA requirements in the long-term management of AIA patients.

Pharmacogenetics of aspirin-intolerant asthma

Leukotriene overproduction is the major characteristic of aspirin-intolerant asthma (AIA). Most studies examining the molecular genetic mechanisms of AIA have focused on leukotriene-related genes, including ALOX5, LTC4S, TXA2R and prostanoid-receptor genes. One study suggested that the human leukocyte antigen (HLA) allele DPB1*0301 may be a genetic marker for the AIA phenotype in European and Asian populations, and HLA-DPB1*0301 has been suggested as a useful genetic marker for predicting more favorable responders to leukotriene-receptor antagonists for long-term management of AIA. Although several reports have indicated possible associations between genetic polymorphisms and variable responses to leukotriene modifiers in nonaspirin sensitive asthmatic patients, few have suggested relationships between such genetic polymorphisms and variable responses to asthma drugs in AIA patients.

Exhaled inflammatory markers in aspirin-induced asthma syndrome

BACKGROUND

Interleukin (IL)-4 and IL-6, respectively, markers of neutrophilic and eosinophilic inflammation, were analyzed in nasal and oral exhaled breath condensate to understand the inflammation of upper and lower airways in subjects with aspirin-induced asthma (AIA) syndrome, evaluating possible differences between AIA and the single pathological conditions included in AIA syndrome.

METHODS

Twelve patients with AIA, 17 patients with mild asthma (MA), 12 patients with nasal polyposis (NP), 11 patients with mild asthma + nasal polyposis (MA + NP), and 10 healthy subjects (HSs) were enrolled. Nasal and oral exhaled IL-4 and IL-6 were measured by enzyme immunoassay kit.

RESULTS

Higher levels of nasal and oral exhaled IL-4 and IL-6 were observed in AIA compared with MA, NP, MA + NP, and HSs. Moreover, a positive correlation was identified between nasal exhaled IL-4 and IL-6 and, respectively, the number of neutrophils and eosinophils and in nasal scraping.

CONCLUSION

The concentration of eosinophilic and neutrophilic markers in upper and lower airways of subjects with AIA syndrome is higher compared with HS and subjects with MA, NP, and MA + NP.

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.

Analysis of perimenstrual asthma based on questionnaire surveys in Japan

BACKGROUND

Perimenstrual asthma (PMA) has been documented in 30% to 40% of asthmatic women; the characteristics of PMA have also been well described. However, there have been few epidemiological investigations of PMA in practice. In this study, we analyzed PMA based on a questionnaire survey carried out in Japan and compared the results with those of studies reported previously.

METHODS

For 8 weeks from September through October 2004, a questionnaire survey was administered to patients with bronchial asthma and their attending physicians. The questionnaire surveyed asthma control, asthma-related emergencies and satisfaction in daily life. The attending physicians were questioned about patient profiles and medications. All female patients who were menstruating during the survey period and who were known to have asthma exacerbation related to menstruation were allocated to the PMA group; those who were not were allocated to the non-PMA group.

RESULTS

The rate of PMA in female patients who were menstruating during the survey period was 11.3% in this study. Characteristic features of the PMA group (n = 54) included more severe disease, worsened disease control and more aggressive patient management, including increased oral corticosteroid use compared with the non-PMA group. The rates of emergency episodes in the PMA group were higher than in the non-PMA group. There was a significant increase in aspirin intolerant asthma (AIA, 25.5%) in the PMA group compared with the non-PMA group (8.4%).

CONCLUSIONS

Attention should be paid to the lack of knowledge regarding PMA in patients with asthma in actual clinical settings. The low rate of PMA reported in this study may be due to the study method using self-reports of PMA by patients without sufficient knowledge, and may not be an accurate representation of the actual incidence of the disease. The clinical similarity of PMA to AIA in this study may also provide a new insight into the mechanism of PMA.

Differential contribution of the CysLTR1 gene in patients with aspirin hypersensitivity

In this study, we compared the roles of CysLT receptor type 1 (CysLTR1) and leukotriene C4 synthase (LTC4S) gene polymorphisms in two major aspirin-related allergic diseases, aspirin-intolerant asthma (AIA) and aspirin-induced chronic urticaria/angioedema (AICU). CysLTR1-634C>T and LTC4S-444A>C polymorphisms were genotyped and its functional effect on the promoter activity was compared. As in vivo functional study, changes of peripheral mRNA level of CysLTR1 were measured by real-time PCR before and after aspirin challenge. A significant association was found for the CysLTR1 promoter polymorphism and the AIA phenotype compared to AICU (P = 0.015). In U937 cells, the variant genotype reporter construct showed significantly higher promoter activity than the common genotype (P < 0.05). The CysLTR1 mRNA levels increased significantly after aspirin challenge in AIA patients (P = 0.013). In conclusion, the CysLTR1 polymorphism may contribute to develop to the AIA phenotype and be used as a genetic marker for differentiating two major aspirin hypersensitivity phenotypes.

Non-invasive measurement of airway inflammation in asthma

Assessing the severity and control of a patient's asthma is of great importance to ensure that pharmacotherapy is optimized. Measures such as lung function, symptoms, and reliever use have traditionally been used as objective means of undertaking this assessment, but until now the level of airway inflammation has not been quantified. As asthma is primarily an inflammatory disorder, it would be desirable to include a measure of this process when evaluating disease control. The following article outlines methods of non-invasively measuring asthmatic airway inflammation and highlights their potential role in clinical practice.

Genetic markers for differentiating aspirin-hypersensitivity

Aspirin-induced asthma (AIA) and aspirin-induced urticaria/ angioedema (AIU) are two major aspirin-related allergies. We summarize recent findings related to their molecular genetic mechanisms in order to identify genetic susceptibility markers for differentiating AIU and AIA. The overproduction of cysteinyl leukotriene has been suggested as a mechanism in both AIU and AIA. Increased expression of CYSLTR1 with CYLSTR1 and CYSLTR2 polymorphisms are new findings in AIA, while the ALOX5 promoter polymorphism has been noted in AIU. An HLA study suggested that DPB1*0301 is a strong genetic marker for AIA, and that HLA DRB1*1302 and DQB1*0609 are markers for AIU susceptibility. Several single nucleotide polymorphisms (SNPs) in the promoters of EP2, TBX21, COX-2, Fc epsilon RIbeta, and TBXA2R were associated with AIA, while an Fc epsilon RIalpha promoter polymorphism was associated with AIU. The functional studies of the key genes involved in AIA and AIU are summarized. The identification and functional study of genetic markers for AIA and AIU susceptibility would further elucidate the pathogenic mechanisms and facilitate the development of early diagnostic markers to establish therapeutic targets.

Contribution of aspirin-intolerant asthma to near fatal asthma based on a questionnaire survey in Niigata Prefecture, Japan

OBJECTIVE

Prevention of deaths due to asthma is one of the most important issues in asthma management. However, there are few epidemiological studies of asthma deaths in Japan.

METHODOLOGY

Over an 8-week period in Niigata Prefecture, Japan, a questionnaire on asthma control and emergency episodes was administered to adult asthmatic patients. A questionnaire was also given to the patients' physicians to obtain further clinical information. Patients who became unconscious during episodes of asthma, or who required intubation and ventilation, were allocated to a near-fatal asthma group (NFA). Patients who did not fulfill these criteria were allocated to the non-NFA group. The NFA group was divided into two subgroups, based on the date of their last NFA episode (old NFA>or= 5 years and recent NFA<4 years).

RESULTS

Characteristic features of the NFA group included severe disease (23.1%vs 7.6%) with more aggressive patient management, including inhaled corticosteroid use (84.3%vs 72.0%). Multiple regression analysis confirmed that aspirin-intolerant asthma (AIA) was strongly associated with NFA. There was no difference in the incidence of AIA between the recent and old NFA patients. This suggests the incidence of AIA in NFA did not improve over time.

CONCLUSIONS

A history of AIA may be a useful indicator of potential NFA and allow preventative methods to be introduced. It is therefore important to obtain a history of AIA and to be aware of the risk of NSAID administration to these patients.

The broken balance in aspirin hypersensitivity

Aspirin was introduced into medicine over a century ago and has become the most popular drug in the world. Although the first hypersensitivity reaction was described soon after aspirin had been marketed, only recently a phenomenon of cysteinyl leukotriene overproduction brought new insights on a balance between pro- and anti-inflammatory mediators derived from arachidonic acid. We describe the most common clinical presentations of aspirin hypersensitivity, i.e. aspirin-induced asthma, rhinosinusitis and aspirin-induced urticaria. We also present their biochemical background. Despite relatively high incidence of these reactions, aspirin hypersensitivity remains underdiagnosed worldwide. Acute reactions of aspirin hypersensitivity are elicited via cyclooxygenase inhibition by non-steroid anti-inflammatory drugs. Coxibs, selective inhibitors of cyclooxygenase-2 isoenzyme, do not precipitate symptoms in susceptible patients. Though hypersensitivity correlates with cyclooxygenase-1 inhibition, diminished tissue expression was described only for cyclooxygenase-2. Aspirin-induced asthma and aspirin-induced urticaria, in a substantial part of the patients, are driven by a release of mediators from activated mast cells. These cells in physiological conditions are under inhibitory control of prostaglandin E2. The origin of aspirin hypersensitivity remains unknown, but accumulating data from genetic studies strongly suggest that environmental factor, possibly a common viral infection, can trigger the disease in susceptible subjects.

Pathogenesis and management of aspirin-intolerant asthma

In 2-23% of adults with asthma, and rarely in children with asthma, aspirin (acetylsalicylic acid) and non-steroidal anti-inflammatory drugs (NSAIDs) cause asthma exacerbations. Within 3 hours of ingestion of aspirin/NSAIDs, individuals with aspirin-intolerant asthma (AIA) develop bronchoconstriction, often accompanied by rhinorrhea, conjunctival irritation, and scarlet flush. In severe cases, a single therapeutic dose of aspirin/NSAIDs can provoke violent bronchospasm, loss of consciousness, and respiratory arrest. In order to diagnose AIA, oral, inhaled, nasal or intravenous aspirin challenge tests are performed in facilities where experienced physicians are present and emergency treatment is available. The exact differences in the pathogenesis of AIA and other types of asthma are not fully understood. The interference of aspirin/NSAIDs with arachidonic acid metabolism in the lungs plays an important role in the mechanism of AIA; inhibition of cyclo-oxygenase is accompanied by overproduction of cysteinyl leukotrienes (cys-LTs). It has been proposed that overproduction of cys-LTs, together with removal by aspirin/NSAIDs of the 'brake' imposed by the bronchodilator prostaglandin E2, may cause an asthma attack in patients with AIA. Development of a suitable animal model to investigate the pathogenesis of AIA would help to clarify this question. Although it is still controversial whether leukotriene modifiers are more effective in patients with AIA compared with other types of asthma, because LT plays an important role in the pathogenesis of AIA, leukotriene modifiers are the preferred medication for the long-term control of AIA. Add-on efficacy of leukotriene modifiers has been confirmed in patients with AIA already treated with inhaled corticosteroids. However, this does not mean that aspirin/NSAIDs can be safely taken by aspirin-sensitive patients treated with leukotriene modifiers. To prevent attacks of AIA, sensitive patients should avoid the use of aspirin/NSAIDs or use selective cyclo-oxygenase 2 inhibitors when required. When patients with AIA need aspirin for specific situations they should receive aspirin desensitization therapy or treatment with selective cyclo-oxygenase 2 inhibitors.

Aspirin-induced asthma: clinical aspects, pathogenesis and management

Aspirin (acetylsalicylic acid)-induced asthma (AIA) consists of the clinical triad of asthma, chronic rhinosinusitis with nasal polyps, and precipitation of asthma and rhinitis attacks in response to aspirin and other NSAIDs. The prevalence of the syndrome in the adult asthmatic populations is approximately 4-10%. Respiratory disease in these patients may be aggressive and refractory to treatment. The aetiology of AIA is complex and not fully understood, but most evidence points towards an abnormality of arachidonic acid (AA) metabolism. Cyclo-oxygenase (COX), the rate-limiting enzyme in AA metabolism, exists as two main isoforms. COX-1 is the constitutive enzyme responsible for synthesis of protective prostanoids, whereas COX-2 is induced under inflammatory conditions. A number of theories regarding its pathogenesis have been proposed. The shunting hypothesis proposes that inhibition of COX-1 shunts AA metabolism away from production of protective prostanoids and towards cysteinyl leukotriene (cys-LT) biosynthesis, resulting in bronchoconstriction and increased mucus production. The COX-2 hypothesis proposes that aspirin causes a structural change in COX-2 that results in the generation of products of the lipoxygenase pathway. It is speculated that this may result in the formation of mediators that cause respiratory reactions in AIA. Related studies provide evidence for abnormal regulation of the lipoxygenase pathway, demonstrating elevated levels of cys-LTs in urine, sputum and peripheral blood, before and following aspirin challenge in AIA patients. These studies suggest that cys-LTs are continually and aggressively synthesised before exposure to aspirin and, during aspirin-induced reactions, acceleration of synthesis occurs. A genetic polymorphism of the LTC4S gene has been identified consisting of an A to C transversion 444 nucleotides upstream of the first codon, conferring a relative risk of AIA of 3.89. Furthermore, carriers of the C444 allele demonstrate a dramatic rise in urinary LTE(4) following aspirin provocation, and respond better to the cys-LT antagonist pranlukast than A444 homozygotes.AIA patients have an aggressive form of disease, and treatment should include combination therapy with inhaled corticosteroids, beta(2)-adrenoceptor agonists and LT modifiers. Furthermore, recently developed inhibitors of COX-2 may be safer in patients with AIA.

Tacrolimus reduces urinary excretion of leukotriene E(4) and inhibits aspirin-induced asthma to threshold dose of aspirin

BACKGROUND

The exact mechanism of aspirin-induced asthma is not clear. It has been postulated that precipitation of asthma attacks by aspirin is linked to inhibition of COX activity and massive release of cysteinyl leukotriene into the airway. Tacrolimus, a macrolide-derived immunosuppressant, is used for immunosuppression in organ transplantation and also for allergic diseases such as atopic dermatitis.

OBJECTIVE

We evaluated the effects of tacrolimus in aspirin-induced asthma by using a double-blind, crossover study design.

METHODS

Twelve patients with aspirin-induced asthma (male:female, 3:9; mean age +/- SD, 36.7 +/- 7.2 years) received either tacrolimus (0.1 mg/kg) or placebo 2 hours before the threshold dose of oral aspirin.

RESULTS

In the placebo arm, oral aspirin significantly decreased FEV 1 concomitant with significant increases in sputum eosinophilic cationic protein and urinary leukotriene E(4) levels. Tacrolimus significantly inhibited bronchoconstriction and abrogated aspirin-induced increase in both sputum eosinophilic cationic protein and urinary leukotriene E(4) levels.

CONCLUSION

The current study suggested that tacrolimus inhibited bronchoconstriction to a threshold dose of aspirin by inhibition of cysteinyl leukotriene excretion.

Role for cysteinyl leukotrienes in allergen-induced change in circulating dendritic cell number in asthma

BACKGROUND

Dendritic cells are important antigen-presenting cells. After an allergen inhalation, their numbers rapidly decrease in circulation and increase in the airway mucosa.

OBJECTIVE

To investigate whether allergen-induced changes in the number of circulating dendritic cells are mediated by cysteinyl leukotrienes.

METHODS

In a randomized, double-blind, crossover study, we examined the effects of 2 weeks of treatment with pranlukast (a cysteinyl leukotriene 1 [CysLT1] receptor antagonist) 300 mg twice daily and placebo on allergen-induced changes in airway responses and circulating dendritic cells in 15 subjects with mild asthma. We examined by flow cytometry, before and at 3 hours and 24 hours after allergen inhalation, the proportion of myeloid (CD33+) and plasmacytoid (CD123+) dendritic cells (HLA-DR+, CD14-, CD16-) among all peripheral blood mononuclear cells. The fraction of dendritic cells expressing CysLT1 receptor was also determined.

RESULTS

Compared with placebo, pranlukast significantly attenuated both the maximum early (by 55%) and the late (by 39%) asthma responses, the allergen-induced methacholine airway hyperresponsiveness, and the increase in macrophage inflammatory protein 1alpha and 3alpha in induced sputum. A significantly greater proportion of CD33+ cells (55%) expressed CysLT1 receptor compared with CD123+ cells (11%). Consistent with this, pranlukast prevented the allergen-induced decrease in CD33+ dendritic cells at 3 hours postallergen (mean Delta from baseline, +4.4%) compared with placebo (mean Delta, -8.4; P <.05), but not CD123+ cells.

CONCLUSION

Pretreatment with pranlukast attenuated allergen-induced airway responses and the decrease in circulating myeloid dendritic cells, demonstrating a novel role of cysteinyl leukotrienes in dendritic cell trafficking.

Cysteinyl leukotrienes regulate dendritic cell functions in a murine model of asthma

Dendritic cells (DCs) act as APCs in the airway and play a critical role in allergy. Cysteinyl leukotrienes (cysLTs) synthesized from arachidonic acid are primary mediators of immediate asthmatic reaction. The aim of this study was to investigate the effects of cysLTs on Dermatophagoides farinae (Der f)-pulsed mouse myeloid DCs in inducing allergic airway inflammation in vitro and in vivo. Control DC (medium-pulsed), Der f-pulsed DC, cysLT-pulsed DC, Der f- and cysLT-pulsed DC, and Der f-pulsed and cysLT receptor antagonist (LTRA)-treated DC were prepared from murine bone marrow, and the production of cytokines ws compared. Subsequently, these DCs were intranasally instilled into another group of naive mice, followed by intranasal Der f challenge to induce allergic airway inflammation in vivo. Der f-pulsed DC produced significantly higher amounts of IL-10 and IL-12 compared with control DC. Der f- and cysLT-pulsed DC further increased IL-10 production compared with Der f-pulsed DC. In contrast, treatment of Der f-pulsed DC with LTRA increased IL-12 and decreased IL-10. Intranasal instillation of Der f-pulsed DC resulted in airway eosinophilia associated with a significant rise in IL-5 levels in the airway compared with control DC. Pulmonary eosinophilia and excess IL-5 were further enhanced in Der f- and cysLT-pulsed DC-harboring mice. In contrast, Der f-pulsed and LTRA-treated DC significantly inhibited airway eosinophilia, reduced IL-5, and increased IFN-gamma in the airway. Our results suggest that cysLTs play an important role in the development of allergic airway inflammation by regulating the immunomodulatory functions of DCs.

The effect of pranlukast on allergen-induced bone marrow eosinophilopoiesis in subjects with asthma

We investigated the mechanisms by which leukotriene receptor antagonists decrease airway eosinophil number. In a randomized, double-blind crossover study, we examined the effects of 2 weeks of treatment with pranlukast 300 mg twice a day or placebo on allergen-induced changes in airway eosinophil number and bone marrow eosinophil progenitors in 15 subjects with mild asthma. Pranlukast treatment for 2 weeks decreased mean sputum eosinophil count from 0.15 x 10(6)/g (5.3% of cells) before treatment to 0.02 x 10(6)/g (0.7% of cells) after treatment (p < 0.05), whereas placebo did not. Pranlukast also decreased the eosinophil count (5.6% at 7 hours and 7.5% at 24 hours) (p < 0.05) after allergen inhalation compared with placebo (13.8% at 7 hours and 15.3% at 24 hours). There was a similar trend for sputum cells immunostaining for EG2, eotaxin, interleukin-5, and regulated upon activation, normal T cell expressed and secreted. Pranlukast also significantly attenuated the allergen-induced increase in the number of bone marrow eosinophil/basophil cfu (mean 0.3) at 24 hours compared with placebo (mean 6.2). The proportion of CD34(+) cells expressing the eotaxin receptor CC chemokine receptor 3, 24 hours after allergen inhalation, was also reduced by pranlukast. We conclude that, the cysteinyl leukotriene receptor antagonist, pranlukast, attenuates allergen-induced increase in airway eosinophils by decreasing bone marrow eosinophilopoiesis and airway chemotactic and eosinophilopoietic cytokines.

Pharmacology of airway inflammation in asthma and COPD

The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term treatment. Although inhaled glucocorticoids are highly effective in controlling airway inflammation in asthma, they are ineffective in the small group of patients with glucocorticoid-dependent and -resistant asthma. With very few exceptions, COPD is caused by tobacco smoking, and smoking cessation is the only truly effective treatment of COPD available. Current pharmacological treatment of COPD is unsatisfactory, as it does not significantly influence the severity of the disease or its natural course. Glucocorticoids are scarcely effective in COPD patients without concomitant asthma. Bronchodilators improves symptoms and quality of life, in COPD patients, but, with the exception of tiotropium, they do not significantly influence the natural course of the disease. Theophylline is the only drug which has been demonstrated to have a significant effect on airway inflammation in patients with COPD. Here we review the pharmacology of currently used antiinflammatory therapies for asthma and COPD and their proposed mechanisms of action. Recent understanding of disease mechanisms in severe steroid-dependent and -resistant asthma and in COPD, has lead to the development of novel compounds, which are in various stages of clinical development. We review the current status of some of these new potential drugs.

Pranlukast: a review of its use in the management of asthma

Pranlukast (Onon, Azlaire), is an orally administered, selective, competitive antagonist of the cysteinyl leukotrienes (LT) C(4), LTD(4) and LTE(4). It is indicated for the prophylactic treatment of chronic bronchial asthma in paediatric and adult patients. The efficacy of pranlukast 225mg twice daily in adults with mild to moderate asthma was demonstrated in double-blind, placebo- or azelastine-controlled studies of 4 or 8 weeks' duration. The drug at this dosage was superior to both comparators in improving mean attack scores and morning and/or evening peak expiratory flow rates, and decreasing the use of rescue bronchodilators (p < 0.05). In limited clinical studies, pranlukast 225mg twice daily appeared to be as effective as montelukast 10mg once daily and zafirlukast 40mg twice daily in adults with mild to moderate asthma. Tachyphylaxis was absent when the drug was administered for up to 4 years. In patients requiring high-dose inhaled corticosteroid therapy, pranlukast 225 mg twice daily plus a halved dosage of inhaled corticosteroid was as effective as the original dosage of inhaled corticosteroid. Pranlukast was also effective in patients with mild to severe asthma in a clinical practice setting. In a double-blind trial, greater improvements in most outcome measures were observed with pranlukast than with oxatomide in children and adolescents with asthma. In clinical trials, pranlukast was well tolerated in adult and paediatric patients with asthma, with an adverse event profile similar to that of placebo. Gastrointestinal events and hepatic function abnormalities were the most commonly reported adverse events. No clinically significant differences in adverse event profiles between pranlukast, zafirlukast or montelukast were shown in limited comparisons. Although Churg-Strauss syndrome has been noted in pranlukast recipients, a direct causal relationship is unlikely.

CONCLUSIONS

Pranlukast is a well tolerated and effective preventative treatment in adult and paediatric patients with persistent asthma of all severities. In some patients, pranlukast may be beneficial when added to low-dose inhaled corticosteroids; it may also be a viable alternative to increasing inhaled corticosteroid dosages. The efficacy of pranlukast relative to placebo has been confirmed; its efficacy relative to other therapy awaits further investigation. Nonetheless, pranlukast is a useful therapeutic option (with as-required short-acting beta(2)-agonists), either as preventative monotherapy for the treatment of mild persistent asthma or in conjunction with inhaled corticosteroids in the management of moderate or severe persistent asthma.

Diarrhea and acaroid mites: A clinical study

AIM: To explore the characteristics of diarrhea caused by acaroid mites.

METHODS: Acaroid mites in fresh stools of 241 patients with diarrhea were separated by flotation in saturated saline. Meanwhile, skin prick test, total IgE and mite-specific IgE were detected in all patients.

RESULTS: The total positive rate of mites in stool samples of the patients was 17.01% (41/241), the positive rates of mites in male and female patients were 15.86% (23/145) and 18.75% (18/96), respectively, without significant difference (P > 0.05). The percentage of skin prick test as" +++", "++", "+", and "-" was 9.13% (22/241), 7.47% (18/241), 5.81% (14/241), 4.98% (12/241) and 72.61% (175/241), respectively. The serum levels of total IgE, mite-specific IgE in patients with and without mites in stool samples were (165.72 ± 78.55) IU/ml, (132.44 ± 26.80) IU/mL and (145.22 ± 82.47) IU/ml, (67.35 ± 45.28) IU/ml, respectively, with significant difference (P < 0.01). The positive rate of mites in stool samples in staffs working in traditional Chinese medicine storehouses or rice storehouses (experimental group) was 26.74% (23/86), which was significantly higher than that (11.61%, 18/155) in people engaged in other professions (χ² = 8.97, P < 0.01).

CONCLUSION: Acaroid mites cause diarrhea and increase serum levels of total IgE and mite-specific IgE of patients, and the prevalence of diarrhea caused by acaroid mites is associated with occupations rather than the gender of patients.

Aspirin-induced asthma: advances in pathogenesis, diagnosis, and management

In some asthmatic individuals, aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygen-ase 1 (COX-1) exacerbate the condition. This distinct clinical syndrome, called aspirin-induced asthma (AIA), is characterized by an eosinophilic rhinosinusitis, nasal polyposis, aspirin sensitivity, and asthma. There is no in vitro test for the disorder, and diagnosis can be established only by provocation challenges with aspirin or NSAIDs. Recent major advances in the molecular biology of eicosanoids, exemplified by the cloning of 2 cysteinyl leukotriene receptors and the discovery of a whole family of cyclooxygenase enzymes, offer new insights into mechanisms operating in AIA. The disease runs a protracted course even if COX-1 inhibitors are avoided, and the course is often severe, many patients requiring systemic corticosteroids to control their sinusitis and asthma. Aspirin and NSAIDs should be avoided, but highly specific COX-2 inhibitors, known as coxibs, are well tolerated and can be safely used. Aspirin desensitization, followed by daily aspirin treatment, is a valuable therapeutic option in most patients with AIA, particularly those with recurrent nasal polyposis or overdependence on systemic corticosteroids.

Acaroid mite, intestinal and urinary acariasis

AIM: To investigate epidemiology and pathogenic mite species of intestinal and urinary acariasis in individuals with different occupations.

METHODS: A total of 1994 individuals were tested in this study. History collection, skin prick test and pathogen identification were conducted. The mites were isolated from stool and urine samples by saturated saline flotation methods and sieving following centrifugation, respectively.

RESULTS: Among the 1994 individuals examined, responses to the skin prick test of “+++”, “++”, “+”, “±” and “-” were observed at frequencies of 3.96% (79), 3.21% (64), 2.31% (46), 1.25% (25) and 89.27% (1780), respectively. A total number of 161 (8.07%) individuals were shown to carry mites, with 92 (4.61%) positive only for stool samples, 37 (1.86%) positive only for urine samples and 32 (1.60%) for both. The positive rate of mites in stool samples was 6.22% (124/1994), being 6.84% (78/1140) for males and 5.39% (46/854) for females. No gender difference was observed in this study (χ² = 1.77, P > 0.05). The mites from stool samples included Acarus siro, TyroPhagus putrescentiae, Dermatophagoides farinae, D. pteronyssinus, Glycyphagus domesticus, G.ornatus, Carpoglyphus lactis and Tarsonemus granaries. The positive rate of mites in urine samples was 3.46% (69/1994). The positive rates for male and female subjects were found to be 3.95% (45/1140) and 2.81% (24/854) respectively, with no gender difference observed (χ² = 1.89, P > 0.05). Mites species in urine samples included Acarus siro, Tyrophagus putrescentiae, T. longior, Aleuroglyphus ovatus, Caloglyphus berlesei, C. mycophagus, Suidasia nesbitti, Lardoglyphus konoi, Glycyphagus domesticus, Carpoglyphus lactis, Lepidoglyphus destructor, Dermatophagoides farinae, D. pteronyssinus, Euroglyphus magnei, Caloglyphus hughesi, Tarsonemus granarus and T. hominis. The species of mites in stool and urine samples were consistent with those separated from working environment. A significant difference was found among the frequencies of mite infection in individuals with different occupations (χ² = 82.55, P < 0.001), with its frequencies in those working in medicinal herb storehouses, those in rice storehouse or mills, miners, railway workers, pupils and teachers being 15.89% (68/428), 12.96% (53/409), 3.28% (18/549), 2.54% (6/236), 5.10% (13/255) and 2.56% (3/117), respectively.

CONCLUSION: The prevalence of human intestinal and urinary acariasis was not associated with gender, and these diseases are more frequently found in individuals working in medicinal herb, rice storehouses or mills and other sites with high density of mites. More attention should be paid to the mite prevention and labor protection for these high-risk groups.

Second-line controller therapy for persistent asthma uncontrolled on inhaled corticosteroids: the step 3 dilemma

The asthma syndrome is characterised by airway inflammation with associated bronchial hyperresponsiveness (BHR) and reversible airflow obstruction. Therapy has benefited from an enhanced understanding of the pathophysiology of asthma and the resulting guidelines that emphasise the pivotal role of anti-inflammatory inhaled corticosteroids (ICS) as first-line therapy. Most patients with mild-to-moderate asthma can be adequately controlled on low-to-medium dosages of ICS alone. For patients with moderate-to-severe asthma who are not adequately controlled by ICS, it is unclear which medication should be added on. The two principal drugs under consideration are long-acting beta(2)-agonists (LABAs) and leukotriene antagonists (LTAs). Although both LABAs and LTAs are both effective at improving lung function, reducing symptoms and decreasing exacerbations, important differences exist that may determine the selection of one over the other in particular circumstances. LABAs and LTAs are equally effective at reducing exacerbations and improving symptoms and quality of life when used as add-on therapy. LABAs tend to be more effective bronchodilators than LTAs. Although LABAs stabilise the airway smooth muscle, they do not affect the underlying inflammatory process. Their long-term use also leads to subsensitivity of response to both LABAs and short-acting beta(2)-agonists (SABAs). The subsensitivity of response to SABAs is more pronounced in the presence of acute bronchoconstriction, which could be relevant during an acute attack. When combined with an ICS, LTAs provide additive non-steroidal anti-inflammatory properties and alleviate associated BHR, but do not induce subsensitivity of response. Not only is the efficacy of LTAs maintained over time, but also they do not affect the response to SABAs as reliever therapy. LTAs also have beneficial effects in patients who have concomitant allergic rhinitis, thus treating the unified airway. The choice between LABA and LTA as add-on therapy will therefore be determined by the needs of the individual patient in terms of providing anti-inflammatory versus bronchodilatory control. For patients with poor lung function where bronchodilatation is required, then an LABA would seem to be a logical choice. For the patient whose lung function is less impaired, with evidence of ongoing BHR where bronchoprotection is needed (e.g. exercise, allergen, cold air), or when there is concomitant allergic rhinitis, then an LTA would be more suitable.