Leukotriene E4 and granulocytic infiltration into asthmatic airways

Increased prostaglandin E2 levels in the airway of patients with eosinophilic bronchitis

BACKGROUND

Eosinophilic bronchitis is a common cause of chronic cough, which like asthma is characterized by sputum eosinophilia, but unlike asthma there is no variable airflow obstruction or airway hyperresponsiveness. We tested the hypothesis that the different airway function in patients with eosinophilic bronchitis and asthma could be caused by an imbalance in the production of bronchoconstrictor (LTC(4)) and bronchoprotective (prostaglandin E(2); PGE(2)) lipid mediators.

METHODS

We measured cytokines levels, proinflammatory mediators and eicosanoids concentration in sputum from 13 subjects with nonasthmatic eosinophilic bronchitis, 13 subjects with asthma, and 11 healthy control subjects. Cytokines mRNA levels were measured by real time PCR, proinflammatory mediators, PGE(2), and LTC(4) were measured by enzyme immunoassays.

RESULTS

The median sputum eosinophil count was not statistically different in patients with asthma (7.95%) and eosinophilic bronchitis (15.29%). The levels of mRNA specific to interleukin-5 (IL-5), IL-4, IL-10, IL-13, interferon gamma (IFN-gamma), IL-2, vascular endothelial growth factor and transforming growth factor beta were similar in both conditions. In addition, no differences were found between asthma and eosinophilic bronchitis in proinflammatory cytokines, such as IL-8, IFN-gamma and tumor necrosis factor alpha (TNF-alpha) levels. Sputum cysteinyl-leukotrienes concentration was raised both in eosinophilic bronchitis and asthma patients. We found that induced sputum PGE(2) concentrations were significantly increased in subjects with eosinophilic bronchitis (838.3 +/- 612 pg/ml) when compared with asthmatic (7.54 +/- 2.14 pg/ml) and healthy subjects (4 +/- 1.3 pg/ml).

CONCLUSION

This data suggest that the difference in airway function observed in subjects with eosinophilic bronchitis and asthma could be due to differences in PGE(2) production in the airways.

Glutamine preferentially inhibits T-helper type 2 cell-mediated airway inflammation and late airway hyperresponsiveness through the inhibition of cytosolic phospholipase A(2) activity in a murine asthma model

BACKGROUND

The non-essential amino acid, l-glutamine (Gln), is abundant in the human body. Gln exhibits beneficial effects on endotoxic shock through the inhibition of cytosolic phospholipase A(2) (cPLA(2)) activity. cPLA(2) has been reported to be implicated in the pathogenesis of asthma, but the effects of Gln on asthma have not yet been defined.

OBJECTIVE

To investigate the effects of Gln on allergic bronchial inflammation and airway hyperresponsiveness (AHR), and to determine the possible action mechanisms of Gln in a murine model of asthma.

METHODS

cPLA(2) phosphorylation was assessed by immunoprecipitation and Western blotting. Smears of bronchoalveolar lavage cells were stained with Diff-Quik solution for differential cell counting. Airway levels of the proteins [T-helper type-1 (Th1) and Th2 cytokines, and mucin] were measured by ELISA. mRNA expression of cytokines was assessed by real-time RT-PCR. AHR was assessed as a change in airway resistance (RL). Histological studies were performed to assess the levels of mucin and pulmonary inflammation.

RESULTS

Systemic Gln administration inhibited cPLA(2) phosphorylation and its enzymatic activity in the lungs. Additionally, Gln effectively suppressed the key features of Th2-dependent asthmatic features, such as airway eosinophilia, mucus formation, and airway type 2 cytokine production, as well as late AHR.

CONCLUSION

Gln was found to be effective in the suppression of Th2-dependent phenotypes and late AHR, and this effect of Gln appeared to be at least partially attributable to its ability to suppress cLPA(2) activity in the airway. Our results suggest that clinical use of Gln for patients with asthma may be beneficial.

Antileukotrienes as adjunctive therapy in acute asthma

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

Cysteinyl-leukotriene levels in sputum differentiate asthma from rhinitis patients with or without bronchial hyperresponsiveness

BACKGROUND

We have previously reported that asthma differs from rhinitis with or without bronchial hyperresponsiveness in the perception and degree of lower airway inflammation.

OBJECTIVE

The aim of the present study was to investigate whether sputum levels of inflammatory markers could further distinguish these patient groups.

METHODS

Patients with seasonal allergic rhinitis with or without asthma or bronchial hyperresponsiveness to methacholine were investigated. Induced sputum was performed during as well as off season, and analysed for cysteinyl-leukotrienes, hyaluronan, eosinophilic cationic protein (ECP) and other inflammatory markers.

RESULTS

Asthmatic patients differentiated from those with rhinitis with or without bronchial hyperresponsiveness in levels of cysteinyl-leukotrienes [geometric mean: 3.3 (lower 95%-upper 95% confidence interval (CI) of geometric mean: 1.9-5.1) vs. 1.4 (0.9-2.2) and 0.7 (0.3-1.6) pg/microg total protein] and hyaluronan [0.30 (0.22-0.43) vs. 0.15 (0.10-0.20) and 0.20 (0.12-0.35) ng/microg total protein] in sputum. The levels of cysteinyl-leukotrienes decreased in sputum from the asthmatic patients, while the levels of hyaluronan remained elevated off-season. Furthermore, elevated levels of ECP were noticed among both the asthmatic and rhinitis patients with hyperresponsiveness compared with controls [0.022 (0.014-0.033) and 0.015 (0.011-0.021) compared with 0.010 (0.007-0.014) ng/microg total protein]. The level of ECP remained elevated off season.

CONCLUSION

Cysteinyl-leukotrienes are possibly more related to mast cell-mediated inflammation and remodelling, also indicated by increased levels of hyaluronan during and off season. This inflammation may be partly different from the eosinophil-driven inflammation.

Cysteinyl leukotrienes enhance tumour necrosis factor-alpha-induced matrix metalloproteinase-9 in human monocytes/macrophages

BACKGROUND

Matrix metalloproteinase-9 (MMP-9) is an important enzyme responsible for airway remodelling. Monocytes/macrophages have a cysteinyl leukotriene 1 (cysLT1) receptor, but its function is poorly understood.

OBJECTIVE

To elucidate the function of the cysLT1 receptor of human monocytes/macrophages in MMP-9 production.

METHODS

We examined the effect of cysLTs (LTC4, -D4 and -E4) on TNF-alpha-induced MMP-9 production in THP-1 cells, a human monocytic leukaemia cell line and peripheral blood CD14+ monocytes/macrophages. In addition, we examined the effect of pranlukast, a cysLT1 receptor antagonist, on the enhancement of TNF-alpha-induced MMP-9 production by cysLTs.

RESULTS

ELISA revealed that LTC4 and -D4, but not -E4, enhanced TNF-alpha-induced MMP-9 production in THP-1 cells and peripheral blood CD14+ monocytes/macrophages. Real-time polymerase chain reaction demonstrated that LTC4 and -D4, but not -E4, increased MMP-9 mRNA expression induced by TNF-alpha in THP-1 cells. Moreover, we demonstrated that pranlukast completely inhibited the enhancement of TNF-alpha-induced MMP-9 production by LTC4 and -D4 in THP-1 cells and peripheral blood CD14+ monocytes/macrophages.

CONCLUSION

LTC4 and -D4 enhanced the TNF-alpha-induced MMP-9 production via binding the cysLT1 receptor in human monocytes/macrophages. Pranlukast inhibited the enhancements by LTC4 and D4.

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.

Differential responses to various classes of drugs in a model of allergic rhinitis in guinea pigs

Different drugs from various pharmacological classes were compared for their ability to protect against the nasal effects of acute allergen challenge in a guinea pig model. In the model, sneezing and nose rubbing were recorded after an initial allergen challenge in guinea pigs previously sensitized to egg albumin. Four days later the same guinea pigs were re-challenged a second time when anesthetised. In these anaesthetized animals, nasal airway pressure, pulmonary inflation pressure and cellular infiltration into nasal lavage fluid were measured. The drug tested were autacoid antagonists (mepyramine--3mg/kg, cetirizine--3mg/kg and montelukast--10mg/kg), L-NAME (10 or 20mg/kg), heparin (20mg/kg) and dexamethasone (20mg/kg) given either intraperitoneally or intravenously; all were given shortly before challenge. Sneezing induced by allergen challenge was statistically significantly reduced by mepyramine, cetirizine and dexamethasone whereas only cetirizine reduced nose rubbing. Changes in nasal airway pressure due to allergen exposure were reduced by cetirizine, montelukast, L-NAME, and heparin, but not by mepyramine, nor dexamethasone. In the presence of L-NAME, nasal airway pressure actually changed in the opposite direction. Cellular infiltration, as assessed by cytometry in nasal lavage fluid 60min after acute allergen challenge, was reduced by montelukast and heparin but not by antihistamines, L-NAME nor dexamethasone. This pattern of effects of the drugs, given by doses and routes previously described in the literature as being effective was not completely consistent with expected responses. The lack of effect of dexamethasone probably reflects the fact that it was given acutely whereas in the clinic chronic administration is used. The two antihistamines were not identical in their actions, presumably reflecting the fact that cetirizine has therapeutic actions not entirely confined to blockade of H1 receptors. Montelukast has not been reported to have major effects on sneezing and itching in the clinic but reduces nasal obstruction (lower nasal airway pressure or nasal patency). Montelukast's effects on cellular infiltration indicate the possible involvement of leukotrienes. Heparin has actions on inflammatory cell infiltration. This could explain its profile of reducing both cellular infiltration, and increased nasal airway pressure.

Comparative study to elucidate the mechanism underlying the difference in airway hyperresponsiveness between two mouse strains

The mechanism underlying airway hyperresponsiveness (AHR), a characteristic feature of asthma, remains obscure. We attempted to elucidate the mechanism responsible for the different degrees of AHR in two mouse strains, BALB/c and C57BL/6, following exposure to an anaphylactic trigger. When ovalbumin (OVA)-sensitized mice were challenged daily with OVA for up to three consecutive days, the BALB/c mice showed a higher degree of airway responsiveness to methacholine than did C57BL/6. Following the OVA challenge, eosinophils and macrophages in bronchoalveolar lavage fluid (BALF) from BALB/c increased significantly in number compared to those from C57BL/6. BALB/c mice also exhibited a higher serum IgE level than that of C57BL/6 after OVA challenge. The enhanced AHR and eosinophilic infiltration in BALF were significantly reduced by pretreatment with a selective cysteinyl-leukotriene type 1 receptor (cysLT(1)R) antagonist, montelukast. In the in vitro study, cysLT production was significantly lower in the dissected lung tissue from BALB/c than in tissue from C57BL/6 when both groups were stimulated with saline. The lungs from BALB/c generated significantly larger amounts of cysLTs on incubation with OVA rather than with saline, while the lungs from C57BL/6 did not show any significant increase in cysLTs with antigen stimulation. Significant upregulation of cysLT(1)R and cysLT(2)R mRNA expression was induced by OVA challenge in the lungs of BALB/c, but not in those of C57BL/6. It is suggested that, after an anaphylactic reaction, the degree of AHR is dependent on the genetic background and that cysLTs play an important role in the mechanism involved.

Montelukast in the treatment of allergic rhinitis: an evidence-based review

Cysteinyl-leukotrienes (CysLTs) are endogenous mediators of inflammation and play an important role in allergic airway disease by stimulating bronchoconstriction, mucus production, mucosal oedema and inflammation, airway infiltration by eosinophils, and dendritic cell maturation that prepares for future allergic response. Montelukast inhibits these actions by blocking type 1 CysLT receptors found on immunocytes, smooth muscle and endothelium in the respiratory mucosa. Initially developed as a treatment for asthma, montelukast has more recently found use in the treatment of allergic rhinitis (AR). We conducted a systematic review of studies that have evaluated montelukast in the treatment of seasonal AR (SAR) and perennial AR (PAR), with and without concomitant asthma. Primary consideration was given to large, randomised, placebo-controlled, double-blind clinical trials in which AR endpoints were assessed and the use of concurrent treatments for AR was excluded. Eight such studies were found in the literature. The primary endpoint in these was daytime nasal symptom severity represented by a composite score derived from individual self-ratings of nasal congestion, rhinorrhoea, nasal pruritus and sneezing. Secondary endpoints have included these individual nasal symptom scores, additional scores for eye, ear and throat symptoms, the impact of rhinitis on quality of sleep, global evaluations of outcome by patients and physicians, and measures of the severity of concomitant asthma. A general outcome was that patients treated with montelukast had significantly greater improvements in their symptoms of SAR and PAR than did patients who were given a placebo. As monotherapy, montelukast exhibited efficacy similar to that of loratadine, but less than that of the intranasally administered corticosteroid fluticasone propionate. The use of montelukast in combination with antihistamines such as loratadine or cetirizine has generally resulted in greater efficacy than when these agents were used alone, and in some studies has produced results comparable with intranasally applied corticosteroids. In patients with AR comorbid with asthma, montelukast treatment has resulted in significant improvements in both, compared with placebo. Montelukast is well tolerated and has a favourable safety profile; adverse events have occurred at similar frequencies in patients taking either montelukast or placebo. Montelukast provides an effective and well tolerated oral treatment for allergic airway inflammation in patients with SAR or PAR without asthma, and in patients in whom AR is comorbid with asthma.

Montelukast decreased exhaled nitric oxide in children with perennial allergic rhinitis

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mast cells and eicosanoid mediators: a system of reciprocal paracrine and autocrine regulation

When activated by specific antigen, complement, or other transmembrane stimuli, mast cells (MCs) generate three eicosanoids: prostaglandin (PG)D(2), leukotriene (LT)B(4), and LTC(4), the parent molecule of the cysteinyl leukotrienes (cysLTs). These diverse lipid mediators, which are generated from a single cell membrane-associated precursor, arachidonic acid, can initiate, amplify, or dampen inflammatory responses and influence the magnitude, duration, and nature of subsequent immune responses. PGD(2) and cysLTs, which were originally recognized for their bronchoconstricting and vasoactive properties, also serve diverse and pivotal functions in effector cell trafficking, antigen presentation, leukocyte activation, matrix deposition, and fibrosis. LTB(4) is a powerful chemoattractant for neutrophils and certain lymphocyte subsets. Thus, MCs can contribute to each of these processes through eicosanoid generation. Additionally, MCs express G-protein-coupled receptors specific for cysLTs, LTB(4), and another eicosanoid, PGE(2). Each of these receptors can regulate MC functions in vivo by autocrine and paracrine mechanisms. This review focuses on the biologic functions for MC-associated eicosanoids, the regulation of their production, and the mechanisms by which eicosanoids may regulate MC function in host defense and disease.

Montelukast with desloratadine or levocetirizine for the treatment of persistent allergic rhinitis

BACKGROUND

Montelukast sodium is approved as a treatment for intermittent and persistent allergic rhinitis (AR), but it has not been evaluated as combined therapy with antihistamines for persistent AR.

OBJECTIVE

To investigate the effects of 6 weeks of treatment of persistent AR with desloratadine, levocetirizine, or montelukast alone or in combination.

METHODS

A randomized, double-blind, placebo-controlled crossover study was performed. Patients were assigned to 2 arms: 20 received montelukast, 10 mg/d, desloratadine, 5 mg/d, or both or placebo and 20 received montelukast, levocetirizine, or both, 5 mg/d, or placebo. The treatment periods were separated by 2-week washout periods. Symptom scoring, skin prick tests, spirometry, rhinometry, and nasal lavage were performed the day before and the last days of the treatment periods. Eosinophil cationic protein levels were evaluated by means of nasal lavage.

RESULTS

The mean +/- SD total baseline nasal symptom score was 7.7 +/- 0.49 before treatment, 3.74 +/- 0.54 after desloratadine use, 3.6 +/- 0.48 after montelukast use, and 3.04 +/- 0.4 after montelukast-desloratadine use. The mean +/- SD baseline nasal symptom score was 7.95 +/- 0.68 before treatment, 3.02 +/- 0.64 after levocetirizine use, 3.44 +/- 0.55 after montelukast use, and 2.14 +/- 0.39 after montelukast-levocetirizine use. The greatest improvement in nasal symptoms occurred after combination treatment. Decreases in the level of eosinophil cationic protein were greater after the combined use of montelukast and antihistamine than after each agent given alone.

CONCLUSIONS

For persistent AR, the combination of montelukast and either desloratadine or levocetirizine is more effective than monotherapy with these agents.

Breaking new ground: challenging existing asthma guidelines

BACKGROUND

While we have international guidelines and various national guidelines for asthma diagnosis and management, asthma remains poorly controlled in many children and adults. In this paper we review the limitations of current asthma guidelines and describe important issues and remaining questions regarding asthma guidelines for use, particularly in primary care.

DISCUSSION

Clinical practice guidelines based on evidence from randomized controlled trials are considered the most rigorous and accurate. Current evidence-based guidelines are written predominantly from the perspective of the patient with a clear-cut asthma diagnosis, however, and tend not to consider the heterogeneity of asthma or to accommodate individual patient variations in response to treatment or their needs, differences in practice settings, or local differences in availability and cost of therapies. The results of randomized controlled trials, which are designed to establish efficacy of treatment under ideal conditions, may not apply to 'real-world' clinical practice, where patients are unselected, monitoring is less frequent, and effectiveness--the benefit of treatment in routine clinical practice--is the most relevant outcome. Moreover, most guidelines see asthma in isolation rather than considering other factors that may impact on asthma and response to asthma therapy, particularly age, allergic rhinitis, cigarette smoking, adherence, and genetic factors. When these links are recognized, guidelines rarely provide practical recommendations for treatment in these scenarios. Finally, there is some evidence that general practitioners are not convinced of the applicability of asthma guidelines to their practice settings, especially when those writing the guidelines principally work in specialist practice.

CONCLUSION

Developing country-specific guidelines or, ideally, local guidelines could provide more practical solutions for asthma care and could account for regional factors that influence patient choice and adherence to therapy. Pragmatic clinical trials and well-designed observational trials are needed in addition to randomized controlled trials to assess real-world effectiveness of therapies, and such evidence needs also to be considered by guideline writers. Finally, practical tools to facilitate the diagnosis and assessment of asthma and factors responsible for poor control, such as associated allergic rhinitis, limited adherence, and smoking behavior, are needed to supplement treatment information provided in clinical practice guidelines for asthma.

Allergic rhinitis and asthma: inflammation in a one-airway condition

Background

Allergic rhinitis and asthma are conditions of airway inflammation that often coexist.

Discussion

In susceptible individuals, exposure of the nose and lungs to allergen elicits early phase and late phase responses. Contact with antigen by mast cells results in their degranulation, the release of selected mediators, and the subsequent recruitment of other inflammatory cell phenotypes. Additional proinflammatory mediators are released, including histamine, prostaglandins, cysteinyl leukotrienes, proteases, and a variety of cytokines, chemokines, and growth factors. Nasal biopsies in allergic rhinitis demonstrate accumulations of mast cells, eosinophils, and basophils in the epithelium and accumulations of eosinophils in the deeper subepithelium (that is, lamina propria). Examination of bronchial tissue, even in mild asthma, shows lymphocytic inflammation enriched by eosinophils. In severe asthma, the predominant pattern of inflammation changes, with increases in the numbers of neutrophils and, in many, an extension of the changes to involve smaller airways (that is, bronchioli). Structural alterations (that is, remodeling) of bronchi in mild asthma include epithelial fragility and thickening of its reticular basement membrane. With increasing severity of asthma there may be increases in airway smooth muscle mass, vascularity, interstitial collagen, and mucus-secreting glands. Remodeling in the nose is less extensive than that of the lower airways, but the epithelial reticular basement membrane may be slightly but significantly thickened.

Conclusion

Inflammation is a key feature of both allergic rhinitis and asthma. There are therefore potential benefits for application of anti-inflammatory strategies that target both these anatomic sites.

Cysteinyl leukotrienes: multi-functional mediators in allergic rhinitis

Cysteinyl leukotrienes (CysLTs) are a family of inflammatory lipid mediators synthesized from arachidonic acid by a variety of cells, including mast cells, eosinophils, basophils, and macrophages. This article reviews the data for the role of CysLTs as multi-functional mediators in allergic rhinitis (AR). We review the evidence that: (1) CysLTs are released from inflammatory cells that participate in AR, (2) receptors for CysLTs are located in nasal tissue, (3) CysLTs are increased in patients with AR and are released following allergen exposure, (4) administration of CysLTs reproduces the symptoms of AR, (5) CysLTs play roles in the maturation, as well as tissue recruitment, of inflammatory cells, and (6) a complex inter-regulation between CysLTs and a variety of other inflammatory mediators exists.

Introduction of leukotriene receptor antagonists in Manitoba

Patient characteristics and prescribing patterns during the introduction of leukotriene receptor antagonists (LTRA) in Manitoba are described using the provincial health database. Residents of Manitoba with asthma, chronic obstructive pulmonary disease, bronchitis or claims for respiratory medications were identified. Six thousand forty-one of 160,626 (3.8%) patients received LTRA; the likelihood of receiving LTRA increased if a patient was younger than 15 years, lived in a rural locale, had asthma, had frequent physician visits or used inhaled corticosteroids. Subsequent prescriptions (68%) were associated with the number of physician visits and inhaled corticosteroid use, which were thought to be indexes of severity. Patients, especially children, who received more than five prescriptions showed evidence of increased asthma control, but there was little evidence of benefit in less selected patient groups due, at least in part, to poor compliance with all respiratory drugs.

Effect of multiple doses of montelukast on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in humans

AIMS

To investigate the effect of multiple dosing with montelukast, a selective leukotriene-receptor antagonist, on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in humans.

METHODS

A two-period, randomized crossover study was conducted in 10 healthy subjects. After administration of oral doses of placebo or 10 mg montelukast daily for 6 days, 4 mg rosiglitazone was administered and plasma samples were obtained for 24 h and analyzed for rosiglitazone and N-desmethylrosiglitazone using high-performance liquid chromatography with fluorescence detection.

RESULTS

During the montelukast phase, the total area under the time-concentration curve (AUC) and peak plasma concentration of rosiglitazone were 102% (90% CI 98, 107%) and 98% (90% CI 92, 103%) of the corresponding values during the placebo phase, respectively. Multiple dosing with montelukast did not affect the oral clearance of rosiglitazone significantly (90% CI 94, 105%; P = 0.50). The AUC ratio and plasma concentration ratios of N-desmethylrosiglitazone : rosiglitazone were not changed by multiple dosing with montelukast (90% CI 90, 103%; P = 0.14).

CONCLUSIONS

Multiple doses of montelukast do not inhibit CYP2C8-mediated rosiglitazone metabolism in vivo despite in vitro findings indicating that montelukast is a selective CYP2C8 inhibitor.

Differential effects of salbutamol and montelukast on eosinophil adhesion and superoxide anion generation

BACKGROUND

Beta2-agonists, a representative class of bronchodilators used for asthma, have been shown to modulate some functions of eosinophils, including cell adhesion. Similarly, a leukotriene receptor antagonist (LTRA) may be beneficial in controlling inflammation in asthma, as cysteinyl leukotrienes (cysLTs) can cause accumulation or activation of eosinophils. Recent evidence suggests that the addition of an LTRA, but not a long-acting beta2-agonist, to inhaled corticosteroid additionally reduces the number of eosinophils in sputum and blood from patients with asthma. The present study examined whether a beta2-agonist and an LTRA differentially modify eosinophil adhesion and activation induced by cysLTs and other activators.

METHODS

Eosinophils were isolated from blood of healthy donors and then incubated in the presence or absence of salbutamol (albuterol) or montelukast. Eosinophils were then exposed to leukotriene D4 (LTD4) or another activator, and the generation of superoxide anion (O2-) was evaluated by cytochrome C reduction assay. Eosinophil adhesion was examined by an eosinophil peroxidase assay.

RESULTS

Montelukast, but not salbutamol (both at 1 microM), inhibited LTD4-induced (100 nM) eosinophil adhesion to recombinant human intercellular adhesion molecule 1. Both drugs similarly and partially inhibited the 100 pM interleukin-5-induced adhesive response of eosinophils to recombinant human intercellular adhesion molecule 1. Montelukast, but not salbutamol, blocked LTD4-induced eosinophil O2- generation of eosinophils. Finally, neither salbutamol nor montelukast modified phorbol myristate acetate (1 ng/ml)-induced O2- generation from eosinophils.

CONCLUSION

These results confirm that LTD4 directly induces activation of eosinophils via the cysLT1 receptor. Furthermore, the results suggest that a beta2-agonist has no effect on eosinophil adhesion and activation induced by cysLTs. These results explain the differential effects of an LTRA and a beta2-agonist in the treatment of eosinophilic inflammation in asthma.

Increased expression of lipoxygenase enzymes during pollen season in nasal biopsies of pollen-allergic patients

BACKGROUND

Exposure of patients sensitized to pollen triggers development of seasonal allergic rhinitis symptoms (SAR). Eicosanoids are a group of arachidonic acid metabolites contributing to the symptoms of SAR. The aim of this study was to investigate seasonal changes in the expression of enzymes of the eicosanoid pathway in the nasal mucosa of patients with SAR.

METHODS

Twenty SAR patients allergic to birch or grass and eight healthy subjects were included in the study. Patients registered rhinoconjunctivitis symptoms and use of rescue medication before and during the pollen season. Nasal biopsies were obtained before and around the peak of the season, sectioned and stained using markers for eosinophils, mast cells, T cells and neutrophils. Antibodies against the following enzymes were also used: cyclo-oxygenase (COX-1, COX-2), 5-lipoxygenase (5-LO), 5-lipoxygenase-activating factor (FLAP), LTA4 hydrolase (LTA4h) and LTC4 synthase (LTC4s).

RESULTS

During the pollen season symptoms of rhinoconjunctivitis and medication score increased significantly (P=0.001; P=0.001 respectively). During the pollen season numbers of eosinophils (P=0.02) and cell positive 5-LO (P=0.02), LTC4s (P=0.04) and LTA4h (P=0.02) increased significantly. During season number of mast cells and cells expressing 5-LO and LTA4h were higher in SAR than in healthy controls group (P=0.02; P=0.01; P=0.03 respectively).

CONCLUSION

In sensitized patients exposure to pollen allergen results in increased expression of enzymes of the eicosanoid pathway.

Do the leukotriene receptor antagonists work in children with grass pollen-induced allergic rhinitis?

Although cysteinyl-leukotriene receptor antagonists were recently approved for use in allergic rhinitis (AR), there has been no study to date investigating their application in children. The aim was to evaluate whether montelukast provides any benefit in nasal allergen challenge-induced symptoms in children, and whether it could improve the control provided by an antihistamine during pollen season. Two randomized studies, one a double-blind, placebo-controlled, nasal allergen challenge study and one an open-label, cross-over, parallel-group clinical study, were performed in 18 (11.7+/-0.7 years) and 32 children (10.5+/-0.5 years), respectively, with grass pollen allergy. In the first study, the effect of a single dose of montelukast and its combination with loratadine were compared with placebo on nasal responses induced by allergen challenge. In the second study, the additive effect of montelukast to loratadine was tested in an open-label cross-over clinical study. In the challenge study, early-phase and late-phase nasal reactions peaked at 15 min and 4 h after the challenge respectively. During the early phase, combination improved total nasal symptoms (p=0.004) during the first hour and sneezing (p=0.012) at 15 min compared with placebo group. During the late phase, montelukast (p=0.017) and combination (p=0.011) caused less nasal obstruction at 4 h and combination caused less sneezing at 6 h (p=0.015). In the clinical trial, montelukast provided protection on seasonal increase in pulmonary symptoms [0 (0, 14) vs. 6.5 (0, 27.7); p=0.016] and on the decrease in FEF25-75 [-0.09 (-0.34, 0.17) vs. -0.28 (-0.66, 0.02); p=0.002]. However, there was no improvement in nasal symptoms and flows. Although we showed protection against nasal challenge-induced congestion with montelukast, we were not able to show the same in the clinical study possibly because of low pollen counts and mildness of the symptoms of the patients with AR. However, montelukast provided better control of pulmonary symptoms and protection from seasonal decrease in lung function, indicating its potential therapeutic benefit in children with AR.

Cysteinyl leukotrienes regulate Th2 cell-dependent pulmonary inflammation

The Th2 cell-dependent inflammatory response is a central component of asthma, and the ways in which it is regulated is a critical question. The cysteinyl leukotrienes (cys-LTs) are 5-lipoxygenase pathway products implicated in asthma, in particular, by their function as smooth muscle constrictors of airways and microvasculature. To elucidate additional roles for cys-LTs in the pathobiology of pulmonary inflammation, we used an OVA sensitization and challenge protocol with mice lacking leukotriene C(4) synthase (LTC(4)S), the terminal enzyme for cys-LT generation. Ag-induced pulmonary inflammation, characterized by eosinophil infiltration, goblet cell hyperplasia with mucus hypersecretion, and accumulation and activation of intraepithelial mast cells was markedly reduced in LTC(4)S(null) mice. Furthermore, Ag-specific IgE and IgG1 in serum, Th2 cell cytokine mRNA expression in the lung, and airway hyperresponsiveness to methacholine were significantly reduced in LTC(4)S(null) mice compared with wild-type controls. Finally, the number of parabronchial lymph node cells from sensitized LTC(4)S(null) mice and their capacity to generate Th2 cell cytokines ex vivo after restimulation with Ag were also significantly reduced. In contrast, delayed-type cutaneous hypersensitivity, a prototypic Th1 cell-dependent response, was intact in LTC(4)S(null) mice. These findings provide direct evidence of a role for cys-LTs in regulating the initiation and/or amplification of Th2 cell-dependent pulmonary inflammation.

Downregulation of leukotriene biosynthesis by thymoquinone attenuates airway inflammation in a mouse model of allergic asthma

Chronic airway inflammation is a key feature of bronchial asthma. Leukotrienes are potent inflammatory mediators that play a role in the pathophysiology of asthma, and their levels are elevated in the airways in response to allergen challenge. We examined the anti-inflammatory effect of thymoquinone (TQ), the active principle in the volatile oil of Nigella sativa seeds, on leukotriene (LT) biosynthesis in a mouse model of allergic asthma. Mice sensitized and challenged with ovalbumin (OVA) antigen had an increased amounts of leukotriene B4 and C4, Th2 cytokines, and eosinophils in bronchoalveolar lavage (BAL) fluid. In addition, there was also a marked increase in lung tissue eosinophilia and goblet cell numbers. Administration of TQ before OVA challenge inhibited 5-lipoxygenase, the main enzyme in leukotriene biosynthesis, expression by lung cells and significantly reduced the levels of LTB4 and LTC4. This was accompanied by a marked decrease in Th2 cytokines and BAL fluid and lung tissue eosinophilia, all of which are characteristics of airway inflammation. These results demonstrate the anti-inflammatory effect of TQ in experimental asthma.

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

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

Protective effect of fish oil supplementation on exercise-induced bronchoconstriction in asthma

BACKGROUND

Previous research has demonstrated that fish oil supplementation has a protective effect on exercise-induced bronchoconstriction (EIB) in elite athletes, which may be attributed to its antiinflammatory properties. Since EIB in asthma involves proinflammatory mediator release, it is feasible that fish oil supplementation may reduce the severity of EIB in asthmatic subjects.

STUDY OBJECTIVES

To determine the efficacy of fish oil supplementation on severity of EIB in subjects with asthma.

DESIGN

Randomized, double-blind, crossover study.

SETTING

Lung function and exercise testing in a university research laboratory.

PATIENTS AND MEASUREMENTS

Sixteen asthmatic patients with documented EIB entered the study on their normal diet and then received either fish oil capsules containing 3.2 g of eicosapentaenoic acid and 2.0 g of docohexaenoic acid (fish oil diet, n = 8) or placebo capsules (placebo diet, n = 8) daily for 3 weeks. At the beginning of the study (normal diet) and at the end of each treatment phase, the following pre-exercise and postexercise measures were assessed: (1) pulmonary function; (2) induced sputum differential cell count percentage and proinflammatory eicosanoid metabolite (leukotriene C4 [LTC4]-leukotriene E4 [LTE4] and prostaglandin D2 [PGD2]) and cytokine (interleukin [IL]-1beta and tumor necrosis factor [TNF]-alpha) concentrations; and (3) eicosanoid metabolites leukotriene B4 (LTB4) and leukotriene B5 (LTB(5)) generation from activated polymorphonuclear leukocytes (PMNLs).

RESULTS

On the normal and placebo diet, subjects exhibited EIB. However, the fish oil diet improved pulmonary function to below the diagnostic EIB threshold, with a concurrent reduction in bronchodilator use. Induced sputum differential cell count percentage and concentrations of LTC4-LTE4, PGD2, IL-1beta, and TNF-alpha were significantly reduced before and following exercise on the fish oil diet compared to the normal and placebo diets. There was a significant reduction in LTB4 and a significant increase in LTB5 generation from activated PMNLs on the fish oil diet compared to the normal and placebo diets.

CONCLUSION

Our data suggest that fish oil supplementation may represent a potentially beneficial nonpharmacologic intervention for asthmatic subjects with EIB.

ALOX5 promoter genotype, asthma severity and LTC production by eosinophils

BACKGROUND

The number of Sp1-Egr1 binding tandem repeats at the ALOX5 promoter influences gene transcription and may modify the response to anti-leukotriene treatment. The relationship of ALOX5 variants to asthma severity and leukotriene production by eosinophils is unknown.

OBJECTIVE

To characterize ALOX5 mRNA expression and cysteinyl-leukotriene production by eosinophils from individuals bearing ALOX5 promoter deletional variants and their association with the severity of childhood asthma.

METHODS

Eosinophils from adult asthmatics bearing only variant alleles (with other than five tandem repeats on both chromosomes, non5/non5) or no variant alleles (5/5) were cultured in vitro and ALOX5 expression and leukotriene secretion were measured. A total of 621 children with mild or moderate-severe asthma were genotyped at the ALOX5 core promoter.

RESULTS

Asthmatics with non5/non5 genotype expressed less ALOX5 mRNA and produced less LTC4 into culture supernatants than 5/5 individuals (6.4 +/- 2.0 and 20.0 +/- 5.0 pg/ml, n = 5; P < 0.05). More asthmatic children bearing non5/non5 genotype had moderate-severe asthma than children with the 5/5 genotype (5.3% vs. 1.4%, P = 0.008). Multivariate logistic regression identified ALOX5 promoter genotype as a significant predictor of disease severity (OR = 3.647, 95% CI: 1.146-11.608, P = 0.03). Consistent with these findings, children bearing the non5/non5 genotype had greater bronchomotor response to exercise as measured by the maximum fall after exercise and the area under the exercise curve (P < 0.05 for both).

CONCLUSION

Our results suggest that children who express the asthma phenotype despite having a genetic variant that impairs their ability to express ALOX5 have more severe disease and thus are more likely to have asthma symptoms.

Cysteinyl-leukotrienes contribute to sputum eosinophil chemotactic activity in asthmatics

BACKGROUND

Cysteinyl-leukotrienes are lipid derived mediators involved in asthma. They are able to stimulate eosinophil chemotaxis in vitro. Induced sputum from asthmatics has been shown to contain eosinophil chemotactic activity. The purpose of our study was to evaluate the contribution of cysteinyl-leukotrienes to sputum eosinophil chemotactic activity in asthmatics and to seek whether there might be differences between asthmatics free of inhaled corticosteroids vs those regularly receiving this treatment.

METHODS

Twenty-two patients (11 corticosteroid free, mean FEV1 99% predicted, 11 corticosteroid-treated, mean FEV1 77% predicted) recruited from our asthma clinic underwent a sputum induction. Sputum was processed according to standard procedure. Eosinophil chemotactic activity contained in the fluid phase was assessed using Boyden microchamber model and expressed as chemotaxis index (CI). Cysteinyl-leukotrienes were measured in sputum supernatant by ELISA and their role in sputum eosionophil chemotactic activity was evaluated by using montelukast, a selective antagonist of a cys-LT1 receptor.

RESULTS

Cysteinyl-leukotrienes were well detectable in sputum supernatants from both steroid-naive (247 +/- 42 pg/ml) and steroid-treated (228 +/- 26 pg/ml) asthmatics. Sputum eosinophil chemotactic activity was indiscriminately present in both corticosteroid-naive (CI: 2.61 +/- 0.22) and corticosteroid-treated (2.98 +/- 0.35) asthmatics. Montelukast (100 microM) significantly inhibited the eosinophil chemotactic activity in both groups achieving a mean inhibition of 54.2 +/- 9.2% (P < 0.001) and 64.7 +/- 7.8% (P < 0.001) in steroid-naive and steroid-treated asthmatics respectively.

CONCLUSION

Cysteinyl-leukotrienes actively participate in sputum eosinophil chemotactic activity found in asthmatics irrespective of whether they are or not under treatment with inhaled corticoids.

Reversal of allergen-induced airway remodeling by CysLT1 receptor blockade

RATIONALE

Airway inflammation in asthma is accompanied by structural changes, including goblet cell metaplasia, smooth muscle cell layer thickening, and subepithelial fibrosis. This allergen-induced airway remodeling can be replicated in a mouse asthma model.

OBJECTIVES

The study goal was to determine whether established airway remodeling in a mouse asthma model is reversible by administration of the cysteinyl leukotriene (CysLT)1 receptor antagonist montelukast, the corticosteroid dexamethasone, or the combination montelukast + dexamethasone.

METHODS

BALB/c mice, sensitized by intraperitoneal ovalbumin (OVA) as allergen, received intranasal OVA periodically Days 14-73 and montelukast or dexamethasone or placebo from Days 73-163.

MEASUREMENTS AND MAIN RESULTS

Allergen-induced trafficking of eosinophils into the bronchoalveolar lavage fluid and lung interstitium and airway goblet cell metaplasia, smooth muscle cell layer thickening, and subepithelial fibrosis present on Day 73 persisted at Day 163, 3 mo after the last allergen challenge. Airway hyperreactivity to methacholine observed on Day 73 in OVA-treated mice was absent on Day 163. In OVA-treated mice, airway eosinophil infiltration and goblet cell metaplasia were reduced by either montelukast or dexamethasone alone. Montelukast, but not dexamethasone, reversed the established increase in airway smooth muscle mass and subepithelial collagen deposition. By immunocytochemistry, CysLT1 receptor expression was significantly increased in airway smooth muscle cells in allergen-treated mice compared with saline-treated controls and was reduced by montelukast, but not dexamethasone, administration.

CONCLUSIONS

These data indicate that established airway smooth muscle cell layer thickening and subepithelial fibrosis, key allergen-induced airway structural changes not modulated by corticosteroids, are reversible by CysLT1 receptor blockade therapy.

Functional characterization of human cysteinyl leukotriene 1 receptor gene structure

The 5-lipoxygenase pathway has been strongly implicated in the pathogenesis of chronic inflammatory disorders, such as bronchial asthma and atherosclerosis. Cysteinyl leukotrienes (cysLTs), 5-lipoxygenase pathway products, are recognized now not only as important factors in asthmatic inflammation, but also as mediators of cell trafficking and innate immune responses. To study a role of cysLTs in inflammatory reactions we have characterized the gene structure of human cysteinyl leukotriene receptor type I (cysLT(1)R). The cysLT(1)R gene consists of 5 exons that are variably spliced and a single promoter region with multiple transcription start sites. Four different cysLT(1)R transcripts were identified. RT-PCR showed dominant and wide expression of the transcript I, containing exons 1, 4, and 5, with the strongest presence in blood leukocytes, spleen, thymus, lung, and heart. The expression of cysLT(1)R is functionally regulated at the transcriptional level by IL-4 through a STAT6 response element localized to the proximal cysLT(1)R promoter region. IL-4 stimulation increased cysLT(1)R mRNA (real-time PCR) and surface protein expression (flow cytometry) in a time-dependent fashion. CysLTs (LTD(4) and LTC(4)) induced an increased production of a potent monocyte chemoattractant CCL2 (MCP-1) in IL-4-primed THP-1 cells in a dose-dependent manner. This effect was effectively inhibited by the cysLT(1)R-selective antagonist MK571 in a dose-dependent manner and only partially by a nonselective cysLT(1)R/cysLT(2)R inhibitor BAY-u9773, implying a cysLT(1)R-mediated mechanism. Thus, cysLTs signaling through cysLT(1)R might contribute to inflammatory reactions by cooperating with IL-4 in enhanced CCL2 production in human monocytic cells.

Naturally occurring parainfluenza virus 3 infection in adults induces mild exacerbation of asthma associated with increased sputum concentrations of cysteinyl leukotrienes

BACKGROUND

Viral respiratory tract infections represent the most frequent cause of asthma exacerbation in both children and adults, but the precise mechanism of such exacerbation remains unknown.

OBJECTIVES

To determine the critical mediator of naturally occurring parainfluenza virus (PIV) 3-induced mild asthma exacerbations in adults.

METHODS

The study subjects were 19 adult asthmatics with mild asthma exacerbation (peak expiratory flow = 60-80% of predicted before bronchodilator use and >80% of predicted after initial bronchodilator treatment). Differential cell counts and concentrations of inflammatory markers including eosinophil cationic protein (ECP), cysteinyl leukotrienes (cysLTs), interleukin (IL)-5, IL-10 and IL-12 were measured in the induced sputum obtained from adults with PIV3- (n = 9) and non-cold-induced (n = 10) exacerbation of asthma during both acute and convalescent phases.

RESULTS

PIV3 infection was confirmed by the presence of viral RNA in nasopharyngeal aspirates. Mild exacerbation of asthma was not associated with significant changes in sputum differential cell counts. Concentrations of sputum ECP and cytokines were comparable between PIV3 and non-cold-induced patients. In contrast, PIV3 infection was associated with a significant increase in sputum cysLTs during the acute phase of mild asthma exacerbation.

CONCLUSIONS

Our results identified cysLTs as a critical mediator of PIV3-induced acute asthma exacerbation.

Association analysis of interleukin 5 receptor alpha subunit (IL5RA) polymorphisms and asthma

The alpha subunit of interleukin 5 receptor (IL5RA) on chromosome 3p26-p24 is known to regulate the development and function of eosinophils. In an effort to discover additional polymorphism(s) in genes whose variant(s) have been implicated in asthma, we investigated the genetic polymorphisms in IL5RA to evaluate the gene as a potential candidate for a host genetic study of asthma. By direct DNA sequencing in 24 individuals, we identified 22 sequence variants within exons and flanking regions including a 1.5-kb promoter region of IL5RA; 10 common polymorphic sites were selected for genotyping in our asthma cohort (n = 587). Two haplotype blocks were identified in a Korean population. Statistical analysis revealed that one promoter SNP, c.-5993A > G, and one ins/del polymorphism in intron 3, c.-480_482insdelGTT, showed significant association with the risk of asthma development. The genetic effects of c.-5993A>G and c.-480_482insdelGTT on asthma were more apparent among atopic subjects. Our findings suggest that polymorphisms in IL5RA might be among the genetic risk factors for asthma development, especially in atopic populations. IL5RA variant/haplotype information identified in this study will provide valuable information for strategies for the control of asthma.

Cysteinyl leukotrienes induce monocyte chemoattractant protein 1 in human monocytes/macrophages

BACKGROUND

Monocytes/macrophages have a cysteinyl leukotriene 1 (CysLT1) receptor, but its function is poorly understood. Objective To elucidate the biological function of the CysLT1 receptor of human monocytes/macrophages.

METHODS

We examined the production of TNF-alpha, IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, monocyte chemoattractant protein 1 (MCP-1), macrophage colony-stimulating factor (M-CSF), and eotaxin induced by CysLTs (leukotriene (LT)C4, -D4, and -E4) in THP-1 cells, a human monocytic leukaemia cell line, and peripheral blood CD14+ monocytes/macrophages. Moreover, we examined the effect of CysLTs on the expression of beta-chemokine receptor 2B (CCR2B) as the receptor of MCP-1 by Western blot analysis.

RESULTS

ELISA revealed that CysLTs induced MCP-1 in THP-1 cells and peripheral blood CD14+ monocytes/macrophages, but not other cytokines. PCR demonstrated that CysLTs increased MCP-1 mRNA expression in THP-1 cells, and Western blotting showed that CysLTs increased the expression of CCR2B in THP-1 cells. Moreover, we demonstrated that pranlukast, a CysLT1 receptor antagonist, blocked MCP-1 production by CysLTs in THP-1 cells almost completely, and partially inhibited MCP-1 release by CysLTs in peripheral blood CD14+ monocytes/macrophages and CCR2B expression by CysLTs in THP-1 cells.

CONCLUSION

CysLTs induce MCP-1 and increase CCR2B expression in human monocytes/macrophages.

Localization and upregulation of cysteinyl leukotriene-1 receptor in asthmatic bronchial mucosa

We have tested the hypothesis that the CysLT(1) receptor is expressed by a variety of bronchial mucosal immune cells and that the numbers of these cells increase in asthma, when stable and in exacerbations. We have applied in situ hybridization and immunohistochemistry to endobronchial biopsy tissue to identify and count inflammatory cells expressing CysLT(1) receptor mRNA and protein, respectively, and used double immunohistochemistry to identify the specific cell immunophenotypes expressing the receptor. Double-labeling demonstrated that bronchial mucosal eosinophils, neutrophils, mast cells, macrophages, B-lymphocytes, and plasma cells, but not T-lymphocytes, expressed the CysLT(1) receptor. The numbers of CysLT(1) receptor mRNA and protein positive inflammatory cells in nonsmoking, nonatopic control subjects without asthma were 13 and 16 mm(-2), respectively (median values; n = 15), and were significantly greater in stable asthma (50 and 43 mm(-2), respectively; n = 17; P < 0.001). Compared with stable asthma, there were further significant increases in subjects hospitalized for a severe exacerbation of their asthma (mRNA: median = 113 and protein: 156 mm(-2); n = 15; P < 0.002). For the combined data of both asthma subgroups, there were strong positive correlations between the increased numbers of CD45+ leukocytes and the greater numbers of cells expressing CysLT(1) receptor (mRNA: r = 0.60, P < 0.001; protein: r = 0.73, P < 0.0001). In conclusion, a variety of immunohistologically distinct inflammatory cells express the CysLT(1) receptor in the bronchial mucosa and both these and the total number of leukocytes increase in mild stable disease and increase further when there is a severe exacerbation of asthma.

The role of leukotrienes in allergic rhinitis

OBJECTIVE

To review the role of cysteinyl leukotrienes (cysLTs) in allergic rhinitis and the scientific rationale for therapy with leukotriene receptor antagonists (LTRAs).

DATA SOURCES

Relevant basic science and clinical articles were identified by a search of the PubMed database for articles published from 1984 to 2004 using the following keywords: allergic rhinitis; nose; immune response; allergen challenge; leukotrienes C, D, and E; cysteinyl leukotriene; cysteinyl leukotriene receptor; cytokine; leukocyte; montelukast; zafirlukast; and pranlukast.

STUDY SELECTION

The authors' expert opinion was used to select studies for inclusion in this review.

RESULTS

CysLTs are synthesized via 5-lipoxygenase metabolism of arachidonic acid by mast cells and basophils during the early-phase response to antigen and by eosinophils and macrophages during the late phase. The cysLT levels in nasal secretions are elevated after short-term allergen instillation and in allergy season in patients with allergic rhinitis. These lipid mediators act locally and systemically by interacting with receptors, particularly the cysLT1 receptor, on target cells. Evidence derived from topical application of cysLTs in the nose and from the effects of LTRAs indicates that cysLTs contribute to nasal mucous secretion, congestion, and inflammation. CysLTs promote allergic inflammation by enhancing immune responses and the production, adhesion, migration, and survival of inflammatory cells such as eosinophils. They also increase the generation of an array of other proinflammatory mediators, such as cytokines, which in turn increase the production of and receptors for cysLTs. Clinical trials have demonstrated that LTRAs have significant but modest efficacy as single agents but additive efficacy when used with other classes of agents.

CONCLUSIONS

CysLTs fulfill the criteria for relevant mediators of allergic rhinitis via their diverse effects on immune, inflammatory, and local structural components of disease. By blocking the cysLT1 receptor responsible for most of these effects, LTRAs represent a useful approach to treatment of this important and prevalent disorder.

Eicosanoids: mediators and therapeutic targets in fibrotic lung disease

Fibrosis is a common end-stage sequella of a number of acute and chronic lung diseases. Current concepts of pathogenesis implicate dysregulated interactions between epithelial cells and mesenchymal cells. Although investigative efforts have documented important roles for cytokines and growth factors in the pathogenesis of fibrotic lung diseases, these observations have not as yet been translated into efficacious therapies, and there is a pressing need for new pathogenetic insights and therapeutic approaches for these devastating disorders. Eicosanoids are lipid mediators derived from arachidonic acid, the most studied of which are the prostaglandins and leukotrienes. Although they are primarily known for their roles in asthma, pain, fever and vascular responses, present evidence indicates that eicosanoids exert relevant effects on immune/inflammatory, as well as structural, cells pertinent to fibrogenesis. In general, leukotrienes promote, whereas prostaglandin E(2) opposes, fibrogenic responses. An imbalance of eicosanoids also exists in pulmonary fibrosis, which favours the production of leukotrienes over prostaglandin E(2). This review highlights the role of this imbalance in the evolution of fibrotic lung disease, discusses the mechanisms by which it may arise and considers approaches for therapeutic targeting of eicosanoids in these conditions.

Allergic challenge-elicited lipid bodies compartmentalize in vivo leukotriene C4 synthesis within eosinophils

Eosinophils are an important source of leukotriene (LT)C(4), which can be synthesized within lipid bodies-cytoplasmic organelles where eicosanoid formation may take place. Allergy-driven lipid body formation and function have never been investigated. Here, we studied the in vivo induction and role of lipid bodies within eosinophils recruited to sites of allergic inflammation. Using two murine models of allergic inflammation (asthma and pleurisy), we verified that parallel to the eosinophil influx, allergic challenge also induced lipid body formation within recruited eosinophils. Neutralizing antibodies to eotaxin/CCL11, RANTES/CCL5, or CCR3 partially inhibited lipid body formation within recruited eosinophils in the allergic pleurisy model. Likewise, intrapleural administration of RANTES or eotaxin also induced significant influx of eosinophils loaded with lipid bodies. By immunolabeling, we detected the presence of a key enzyme involved in the leukotriene metabolism-5-lipoxygenase-within eosinophil lipid bodies formed in vivo after allergen challenge. Furthermore, specific immunolocalization of newly formed LTC(4) demonstrated that lipid bodies were the sites of formation of this eicosanoid within infiltrating eosinophils. Therefore, allergic inflammation triggers in vivo formation of new lipid bodies within infiltrating eosinophils, a phenomenon largely mediated by eotaxin/RANTES acting via CCR3 receptors. Such in vivo allergen-driven lipid bodies function as intracellular compartments of LTC(4) synthesis.

Effect of the cysteinyl leukotriene antagonist pranlukast on transendothelial migration of eosinophils

BACKGROUND

Evidence shows that leukotriene receptor antagonist (LTRA) can cause a partial reduction of eosinophils in the asthmatic airway. Although cysteinyl leukotrienes (CysLTs) can regulate the development of eosinophilic inflammation, LTRA might modulate the eosinophilic response to other inflammatory molecules involved in allergic inflammation. Montelukast is an LTRA that inhibits eosinophil transendothelial migration (TEM) in response to platelet-activating factor (PAF). The present study evaluates whether pranlukast (an LTRA) modifies eosinophil TEM in response to chemoattractants including PAF and C-C chemokines.

METHODS

Eosinophils isolated from the blood of healthy individuals were incubated with or without pranlukast. We then evaluated eosinophil transmigration across human umbilical vein endothelial cells in response to LTD(4), eotaxin, RANTES and PAF.

RESULTS

Pranlukast did not modify the spontaneous transmigration of eosinophils (n = 5). As reported, eosinophil TEM was significantly augmented by 0.1 microM LTD(4) and this enhancement was blocked by 1 microM pranlukast (p < 0.001; n = 6). On the other hand, pranlukast did not modify eosinophil transmigration in response to eotaxin, RANTES, or PAF (p > 0.1; n = 5).

CONCLUSION

The inhibitory effect of pranlukast on eosinophil transmigration is highly specific for the CysLT1-dependent pathway.

Safety, tolerability, and exploratory efficacy of montelukast in 6- to 24-month-old patients with asthma

OBJECTIVE

The purpose of this study was to determine the safety and tolerability profile of montelukast 4-mg oral granules compared with placebo in children aged 6-24 months with asthma.

METHODS

This was a randomized, double-blind, placebo-controlled, parallel-group study. Children 6-24 months of age at first visit with a history of at least three episodes of physician-diagnosed asthma or 'asthma-like' symptoms and in need of controller therapy were randomized to either montelukast 4-mg oral granules or placebo once daily in the evening for 6 weeks. The primary variables were the frequency of clinical and laboratory adverse experiences. The exploratory efficacy endpoints included days without beta-agonist use, beta-agonist use per day, unscheduled physician or hospital visits for asthma, oral corticosteroid rescues for asthma, asthma attacks, discontinuation due to worsening of asthma, and total blood peripheral eosinophil counts.

RESULTS

The most common clinical adverse experiences were upper respiratory tract infection, asthma, fever, diarrhea, and vomiting occurring with similar frequencies between treatment groups. There were no clinically meaningful differences between the two treatment groups in clinical or laboratory adverse experiences and no significant differences in frequency of patients with elevated serum transaminases. Differences between the montelukast and placebo treatment groups in the exploratory efficacy endpoints of days without beta-agonist use, oral corticosteroid rescues, emergency care, asthma attacks, and discontinuations due to worsening asthma were not significant.

CONCLUSIONS

Montelukast, 4-mg oral granules, was well tolerated over 6 weeks of treatment in children aged 6-24 months with asthma.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A population pharmacokinetic model for montelukast disposition in adults and children

PURPOSE

The purpose was to develop a population pharmacokinetic model for montelukast after intravenous administration. Clinical trial simulations were conducted using the model developed to identify the lowest intravenous dose in 6- to 14-year-old children that would give montelukast systemic exposures that were comparable to those found to be associated with efficacy in adults.

METHODS

Two clinical studies were conducted where montelukast was administered intravenously as a 7-mg dose to adults and as a 3.5-mg dose to children aged 6 to 14 years. Model development included defining the base pharmacostatistical model and investigating the effects of demographic variables [age and total body weight (TBW)] on the structural parameters, using a nonlinear mixed effect modeling approach.

RESULTS

A linear three-compartment pharmacokinetic model was found to best describe the disposition of montelukast. Inclusion of TBW as a covariate caused a 35% and 63% decrease in the interindividual variabilities on clearance and central volume of distribution, respectively. Trial simulations suggested that a 5.25-mg intravenous dose of montelukast should be chosen in children aged 6 to 14 years.

CONCLUSIONS

The model developed can adequately describe the intravenous pharmacokinetics of montelukast and can be used as a useful tool for dose selection in pediatric subpopulations.

The effect of montelukast versus usual care on health care resource utilization in children aged 2 to 5 years with asthma

BACKGROUND

Limited clinical data are available on the long-term effects of asthma controller therapy on the utilization of health care resources in pediatric patients with asthma.

OBJECTIVE

The objective of this study was to compare the effects of long-term treatment with montelukast and usual care on health care resource use in children with asthma.

METHODS

Pediatric patients aged 2 to 5 years with asthma who had completed a 3-month, double-blind, double-dummy clinical trial comparing montelukast 4 mg and placebo were asked to participate in an open-label, controlled extension study comparing montelukast 4 mg and usual care. Usual care was defined as cromolyn or inhaled corticosteroid therapy Health care resource utilization was measured in terms of oral corticosteroid use and numbers of physician visits, emergency department visits, and hospitalizations.

RESULTS

Of 618 patients who completed the primary phase of the study, 516 (83.5%) participated in the extension study Data from 506 patients (302 without previous asthma maintenance therapy, 204 with) were included in the analysis. During the extension phase, patients who received montelukast and had not used previous asthma maintenance therapy were followed for a mean of 329.5 days; those who received usual care and

CONCLUSION

In this open-label study, pediatric patients aged 2 to 5 years with mild to moderate persistent asthma receiving long-term therapy with montelukast had similar rates of asthma-related health care resource utilization compared with those receiving usual care with cromolyn or inhaled corticosteroids.

Leukotriene E(4)-induced persistent eosinophilia and airway obstruction are reversed by zafirlukast in patients with asthma

BACKGROUND

We have shown that inhalation of leukotriene (LT) E 4 contributes to specific recruitment of eosinophils to the airway mucosa in patients with asthma at the time of maximal decrease in airway-specific conductance.

OBJECTIVE

We examined the ability of the cysteinyl LT 1 receptor antagonist, zafirlukast, to improve or prevent LT-mediated eosinophilia and airway obstruction in asthma.

METHODS

Bronchial biopsies were taken and pulmonary function was measured before and 4 to 6 hours after the dose of inhaled LTE 4 causing a > or =15% fall in FEV 1 at baseline both at week 0 and after 6-week randomly assigned treatment with a high dose of zafirlukast, 80 mg twice daily.

RESULTS

Leukotriene E 4 inhalation at week 0 doubled the number of eosinophils in the airway mucosa in 21 of 25 patients with mild asthma, increased the numbers of neutrophils and lymphocytes, and decreased FEV 1 (-17%). Zafirlukast reduced both airway eosinophilia and obstruction in FEV 1 , whereas with a double-blind placebo treatment, the effect of LTE 4 on both parameters persisted for 6 weeks. On repeat LTE 4 inhalation challenge after 6 weeks, zafirlukast treatment prevented further airway eosinophilia and decrease in FEV 1 seen in the placebo group.

CONCLUSION

Persistent LTE 4 -induced airway eosinophilia may form the basis of an amplification mechanism for further eosinophil recruitment. Zafirlukast prevents LTE 4 -induced eosinophilic airway inflammation in mild asthma.

Zafirlukast treatment for acute asthma: evaluation in a randomized, double-blind, multicenter trial

CONTEXT

Acute asthma causes nearly 2 million hospital emergency department (ED) visits in the United States annually, and hospitalization after an ED visit and relapse after ED discharge are common.

OBJECTIVE

To evaluate the adding of therapy with zafirlukast to standardized care for patients with acute asthma in the ED and a 28-day follow-up period.

DESIGN AND PATIENTS

A total of 641 patients presenting to the ED with acute asthma were randomized to receive either single-dose zafirlukast, 160 mg (Z160) [162 patients], zafirlukast, 20 mg (Z20) [158 patients]), or placebo (321 patients) as adjunct treatment to standard care in this double-blind, multicenter trial. Assessments, including spirometry and symptom scores, were obtained before each albuterol treatment and at 4 h. Patients who were discharged from the ED after 4 h continued outpatient therapy over a 28-day period and received either Z20 bid (276 patients) or placebo (270 patients) in addition to prednisone, albuterol, and their previous asthma medications. FEV(1) was measured at clinic visits on days 10 and 28. Patients recorded outpatient clinical data twice daily on a home diary card.

MAIN OUTCOME MEASURES

the effect of zafirlukast on relapse after ED discharge. Other assessments were the rate of extended care (ie, ED stay for > 4 h or hospitalization), FEV(1), and symptoms.

RESULTS

At the end of the outpatient period, 65 of 276 patients (23.6%) treated with zafirlukast and 78 of 270 patients (28.9%) treated with placebo relapsed (p = 0.047; absolute reduction, 5.3%; relative reduction, 18.3%). At the end of the ED period, 16 of 162 patients (9.9%) treated with Z160, 26 of 158 patients (16.5%) treated with Z20, and 48 of 321 patients (15.0%) treated with placebo required extended care (p = 0.052; absolute reduction with Z160 compared to placebo, 5.1%; relative reduction, 34%). These findings were supported by a significant improvement in FEV(1) and dyspnea in the ED with the use of Z160 therapy, and by greater improvement in FEV(1) and symptoms during the outpatient period for patients treated with Z20.

CONCLUSIONS

When added to standardized care, therapy with Z20 bid reduced the risk of relapse compared with placebo over a 28-day treatment period. One dose of Z160 in the ED also reduced the rate of extended care.

Leukotriene D4 and eosinophil transendothelial migration, superoxide generation, and degranulation via beta2 integrin

BACKGROUND

Evidence indicates that cysteinyl leukotriene (cysLT) 1 receptor antagonists possess anti-inflammatory properties in asthmatic patients in vivo. Although the exact mechanisms of these actions remain unknown, cysLTs regulate the locomotion and functions of eosinophils. We previously reported that leukotriene D4 augments the expression of eosinophil beta2 integrin and the adhesion of eosinophils to rh intercellular adhesion molecule 1 via beta2 integrin.

OBJECTIVE

To examine whether leukotriene D4 modifies the transendothelial migration (TEM) and effector functions of eosinophils.

METHODS

We evaluated the effects of leukotriene D4 on (1) eosinophil TEM across human umbilical vein endothelial cells, (2) superoxide anion (O2-) generation, and (3) eosinophil-derived neurotoxin release in eosinophils isolated from the blood of healthy individuals.

RESULTS

Leukotriene D4 (0.1-1 microM) significantly induced eosinophil TEM, O2- generation, and eosinophil-derived neurotoxin release. Pranlukast, a cysLT1 receptor antagonist, significantly inhibited all of these parameters, although the inhibitory effect on O2- generation was partial. All of these responses were significantly inhibited by anti-beta2 integrin but not by anti-alpha4 integrin antibodies.

CONCLUSIONS

Leukotriene D4 directly up-regulates the TEM and effector functions of eosinophils mainly via the cysLT1 receptor and beta2 integrin. These effects of leukotriene D4 probably contribute to the manifestation of eosinophil inflammation in asthmatic airways.

Role of human mast cells and basophils in bronchial asthma

Mast cells and basophils are the only cells expressing the tetrameric (alphabetagamma2) structure of the high affinity receptor for IgE (FcepsilonRI) and synthesizing histamine in humans. Human FcepsilonRI+ cells are conventionally considered primary effector cells of bronchial asthma. There is now compelling evidence that these cells differ immunologically, biochemically, and pharmacologically, which suggests that they might play distinct roles in the appearance and fluctuation of the asthma phenotype. Recent data have revealed the complexity of the involvement of human mast cells and basophils in asthma and have shed light on the control of recruitment and activation of these cells in different lung compartments. Preliminary evidence suggests that these cells might not always be detrimental in asthma but, under some circumstances, they might exert a protective effect by modulating certain aspects of innate and acquired immunity and allergic inflammation.

Pharmacokinetics of montelukast in asthmatic patients 6 to 24 months old

Montelukast is a cysteinyl leukotriene receptor antagonist approved for the treatment of asthma for those ages 1 year old to adult. The purpose of this study was to evaluate the pharmacokinetic comparability of a 4-mg dose of montelukast oral granules in patients > or = 6 to < 24 months old to the 10-mg approved dose in adults. This was an open-label study in 32 patients. Population pharmacokinetic parameters included estimates of AUC(pop), C(max), and t(max). Results were compared with estimates from adults (10-mg film-coated tablet [FCT]). Dose selection criteria were for the 95% confidence interval (CI) for the AUC(pop) estimate ratio (pediatric/adult 10 mg FCT) to be within comparability bounds of (0.5, 2.00). The AUC(pop) ratio and the 95% CI for children compared with adults were within the predefined comparability bounds. Observed plasma concentrations were also similar. Based on systemic exposure of montelukast, a 4-mg dose of montelukast appears appropriate for children as young as 6 months of age.

Urinary eicosanoid and tyrosine derivative concentrations in patients with vasculitides

BACKGROUND

Vasculitides are classified on the basis of the type of cell involved, namely, eosinophilic vasculitides such as Churg-Strauss syndrome (CSS) and noneosinophilic vasculitides. However, knowledge on inflammatory mediators and oxidative tissue damage associated with vasculitides is insufficient.

OBJECTIVE

We measured the urinary concentrations of inflammatory mediators and tyrosine derivatives to assess biomarkers associated with the pathophysiology of vasculitides.

METHODS

Urine was collected from 9 patients with CSS during acute exacerbation and during clinical remission, 24 patients with rheumatoid arthritis in stable condition, and 8 patients with vasculitis diseases (VDs) during acute exacerbation. Leukotriene E 4 (LTE 4 ), 9alpha,11beta prostaglandin F 2 , and eosinophil-derived neurotoxin (EDN) concentrations were determined by enzyme immunoassay. 3-Bromotyrosine (BrY) and 3-chlorotyrosine (ClY) concentrations were determined by gas chromatography-mass spectrometry.

RESULTS

The urinary LTE 4 , EDN, BrY, and ClY concentrations were significantly higher in the patients with CSS during acute exacerbation than in healthy control subjects and, except for urinary ClY concentration, significantly decreased during clinical remission. The urinary EDN and BrY concentrations were significantly higher in patients with CSS during acute exacerbation than in patients with VD during acute exacerbation. Only urinary LTE 4 concentration was significantly different between the patients with rheumatoid arthritis in stable condition and the patients with VD during acute exacerbation.

CONCLUSION

Oxidative tissue damage caused by eosinophil peroxidase is a pathophysiological characteristic of eosinophil-associated diseases such as CSS. Urinary LTE 4 concentration may reflect a pathophysiological event involved in eosinophilic and noneosinophilic vasculitides. Cysteinyl-leukotriene pathways are potential therapeutic targets for small-vessel vasculitides.