High levels of urinary leukotriene E4 excretion in steroid treated patients with severe asthma

Are leukotrienes really the world's best bronchoconstrictors and at least 100 to 1000 times more potent than histamine?

It has been stated numerous times that leukotrienes are 100 to 1000 times more potent compared with histamine, but is this statement correct? Can we really compare a charged mono-cation with lipoid amphiphiles in their ability to penetrate an epithelial cell layer after inhalation challenge? In this review we question the shift in clinical and drug development attention from histamine towards leukotriene receptor antagonists for the treatment of chronic asthma and acute asthma exacerbations. The presented data indicate that histamine very likely plays a much more important role than previously assumed. It is time to rethink mediator involvement during bronchospasm and shift attention back to histamine.

Differential expression of eicosanoid pathways after whole blood stimulation in asthma patients

Objectives

Asthma is a heterogeneous disease regarding its pathophysiology, clinical symptoms, and response to treatment. Eicosanoids are important inflammatory mediators, able to either promote or attenuate the underlying chronic airway inflammation. We compared eicosanoid expression patterns in the blood circulation and in stimulated blood leukocytes of asthma patients to identify differences in eicosanoid release which may be related to airway inflammation.

Methods

Blood was collected from 198 adult asthmatic patients and 63 healthy controls, participating in the German Center for Lung Research (DZL) ALLIANCE cohort. Eicosanoid release from leukocytes was analyzed using heparinized whole blood after in vitro stimulation with zymosan. Additionally, circulating eicosanoids were measured directly from ethylenediaminetetraacetic acid (EDTA) plasma. Eicosanoids were extracted via solid phase extraction and quantified by high-performance-liquid-chromatography-tandem-mass-spectrometry (HPLC-MS2).

Results

Eicosanoid levels were low in blood circulation with no significant differences between asthmatics and controls, except for leukotriene E4 (LTE4) which was slightly elevated in asthmatics. After in vitro stimulation we observed an inhibition of prostaglandin and thromboxane biosynthesis only in patients with severe asthma which was related to the regular use of systemic corticosteroids. In contrast, a significant increase was shown for formation of the 5-Lipoxygenase (5-LOX) product LTE4 in steroid-naïve asthmatics with moderate as well as severe disease severity but not in subjects with systemic steroid treatment. Furthermore 15-Hydorxyeicosatetraenoic acid (15-HETE) production was elevated in asthmatic patients with mild-to-moderate disease activity but dropped down in severe asthmatics.

Conclusions

Profiling of eicosanoid production in stimulated whole blood samples showed a specific biosynthesis pattern of asthmatic patients, which is influenced by the use of systemic corticosteroids.

Evaluation of urinary cysteinyl leukotrienes as biomarkers of severity and putative therapeutic targets in COVID-19 patients

BACKGROUND

Cysteinyl leukotrienes (CysLT) are potent inflammation-promoting mediators, but remain scarcely explored in COVID-19. We evaluated urinary CysLT (U-CysLT) relationship with disease severity and their usefulness for prognostication in hospitalized COVID-19 patients. The impact on U-CysLT of veno-venous extracorporeal membrane oxygenation (VV-ECMO) and of comorbidities such as hypertension and obesity was also assessed.

METHODS

Blood and spot urine were collected in "severe" (n = 26), "critically ill" (n = 17) and "critically ill on VV-ECMO" (n = 17) patients with COVID-19 at days 1-2 (admission), 3-4, 5-8 and weekly thereafter, and in controls (n = 23) at a single time point. U-CysLT were measured by ELISA. Routine markers, prognostic scores and outcomes were also evaluated.

RESULTS

U-CysLT did not differ between groups at admission, but significantly increased along hospitalization only in critical groups, being markedly higher in VV-ECMO patients, especially in hypertensives. U-CysLT values during the first week were positively associated with ICU and total hospital length of stay in critical groups and showed acceptable area under curve (AUC) for prediction of 30-day mortality (AUC: 0.734, p = 0.001) among all patients.

CONCLUSIONS

U-CysLT increase during hospitalization in critical COVID-19 patients, especially in hypertensives on VV-ECMO. U-CysLT association with severe outcomes suggests their usefulness for prognostication and as therapeutic targets.

Urine Leukotriene E4: Implications as a Biomarker in Chronic Rhinosinusitis

OBJECTIVE

To provide a comprehensive state-of-the-art review of the emerging role of urine leukotriene E4 (uLTE4) as a biomarker in the diagnosis of chronic rhinosinusitis (CRS), aspirin-exacerbated respiratory disease (AERD), and asthma.

DATA SOURCES

Ovid MEDLINE(R), Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus.

REVIEW METHODS

A state-of-the-art review was performed investigating the role of uLTE4 as a diagnostic biomarker, predictor of disease severity, and potential marker of selected therapeutic efficacy.

CONCLUSIONS

uLTE4 has been shown to be a reliable and clinically relevant biomarker for CRS, AERD, and asthma. uLTE4 is helpful in ongoing efforts to better endotype patients with CRS and to predict disease severity.

IMPLICATIONS FOR PRACTICE

Aside from being a diagnostic biomarker, uLTE4 is also able to differentiate aspirin-tolerant patients from patients with AERD and has been associated with objective disease severity in patients with CRS with nasal polyposis. uLTE4 levels have also been shown to predict response to medical therapy, particularly leukotriene-modifying agents.

Urinary Leukotriene E4 and Prostaglandin D2 Metabolites Increase in Adult and Childhood Severe Asthma Characterized by Type 2 Inflammation. A Clinical Observational Study

Rationale: New approaches are needed to guide personalized treatment of asthma.Objectives: To test if urinary eicosanoid metabolites can direct asthma phenotyping.Methods: Urinary metabolites of prostaglandins (PGs), cysteinyl leukotrienes (CysLTs), and isoprostanes were quantified in the U-BIOPRED (Unbiased Biomarkers for the Prediction of Respiratory Diseases Outcomes) study including 86 adults with mild-to-moderate asthma (MMA), 411 with severe asthma (SA), and 100 healthy control participants. Validation was performed internally in 302 participants with SA followed up after 12-18 months and externally in 95 adolescents with asthma.Measurement and Main Results: Metabolite concentrations in healthy control participants were unrelated to age, body mass index, and sex, except for the PGE₂ pathway. Eicosanoid concentrations were generally greater in participants with MMA relative to healthy control participants, with further elevations in participants with SA. However, PGE₂ metabolite concentrations were either the same or lower in male nonsmokers with asthma than in healthy control participants. Metabolite concentrations were unchanged in those with asthma who adhered to oral corticosteroid treatment as documented by urinary prednisolone detection, whereas those with SA treated with omalizumab had lower concentrations of LTE₄ and the PGD₂ metabolite 2,3-dinor-11β-PGF_2α. High concentrations of LTE₄ and PGD₂ metabolites were associated with lower lung function and increased amounts of exhaled nitric oxide and eosinophil markers in blood, sputum, and urine in U-BIOPRED participants and in adolescents with asthma. These type 2 (T2) asthma associations were reproduced in the follow-up visit of the U-BIOPRED study and were found to be as sensitive to detect T2 inflammation as the established biomarkers.Conclusions: Monitoring of urinary eicosanoids can identify T2 asthma and introduces a new noninvasive approach for molecular phenotyping of adult and adolescent asthma.Clinical trial registered with www.clinicaltrials.gov (NCT01976767).

Zileuton use and phenotypic features in asthma

Zileuton, a 5-lipoxygenase (5LPO) inhibitor exerts a broad influence in the arachidonic acid (AA) pathway by blocking upstream molecules that otherwise would lead to production of an array of inflammatory leukotrienes (LT) A4-E4. Hence, it has the potential to be a drug suitable to treat complicated asthmatics. Studies have shown modest response rates for zileuton in asthmatics.

OBJECTIVE

We sought to study our hypothesis that response to zileuton varies across specific asthmatic phenotypes.

METHODS

We retrospectively analyzed data from 129 patients with asthma that were prescribed zileuton at the University of Pittsburgh's Comprehensive Lung Clinic. A total of 75 patients from the above population had requisite lung function data and zileuton usage that would help assess a drug response effect. A zileuton responder was defined as having at least or greater than 5% annualized increase in post-bronchodilator FEV1% from baseline. Using a multivariate logistic regression analysis, we determined the association between responder status and the underlying phenotypic characteristics.

RESULTS

Using generalized estimating equations (GEE) analysis of 331 individual lung function test data-points as well as logistic regression analysis for predictors of 5% or more annualized increase in FEV1%, 21 of 75 patients (28%) met criteria for having a differential response to zileuton. Severe asthma was associated less often with responder status (OR 0.12; p 0.004). Obesity was less often associated with responder status, however did not reach significance (OR 0.46; p 0.15).

CONCLUSION

In this retrospective study, zileuton response varies across asthmatics, with poorer response rates being associated with those with severe asthma and possibly obesity. Although prescription trends for zileuton may predominate amongst severe asthmatics, this tendency does not seem to mirror the actual likelihood to respond. As against the trivial role for zileuton per current GINA algorithms, our study brings forward a notion that zileuton may well be considered along with LTRAs (like montelukast) for non-severe asthma.

Discovery of the Oral Leukotriene C4 Synthase Inhibitor (1S,2S)-2-({5-[(5-Chloro-2,4-difluorophenyl)(2-fluoro-2-methylpropyl)amino]-3-methoxypyrazin-2-yl}carbonyl)cyclopropanecarboxylic Acid (AZD9898) as a New Treatment for Asthma

While bronchodilators and inhaled corticosteroids are the mainstay of asthma treatment, up to 50% of asthmatics remain uncontrolled. Many studies show that the cysteinyl leukotriene cascade remains highly activated in some asthmatics, even those on high-dose inhaled or oral corticosteroids. Hence, inhibition of the leukotriene C4 synthase (LTC4S) enzyme could provide a new and differentiated core treatment for patients with a highly activated cysteinyl leukotriene cascade. Starting from a screening hit (3), a program to discover oral inhibitors of LTC4S led to (1S,2S)-2-({5-[(5-chloro-2,4-difluorophenyl)(2-fluoro-2-methylpropyl)amino]-3-methoxypyrazin-2-yl}carbonyl)cyclopropanecarboxylic acid (AZD9898) (36), a picomolar LTC4S inhibitor (IC₅₀ = 0.28 nM) with high lipophilic ligand efficiency (LLE = 8.5), which displays nanomolar potency in cells (peripheral blood mononuclear cell, IC_50,free = 6.2 nM) and good in vivo pharmacodynamics in a calcium ionophore-stimulated rat model after oral dosing (in vivo, IC_50,free = 34 nM). Compound 36 mitigates the GABA binding, hepatic toxicity signal, and in vivo toxicology findings of an early lead compound 7 with a human dose predicted to be 30 mg once daily.

The Role of Leukotrienes as Potential Therapeutic Targets in Allergic Disorders

Leukotrienes (LTs) are lipid mediators that play pivotal roles in acute and chronic inflammation and allergic diseases. They exert their biological effects by binding to specific G-protein-coupled receptors. Each LT receptor subtype exhibits unique functions and expression patterns. LTs play roles in various allergic diseases, including asthma (neutrophilic asthma and aspirin-sensitive asthma), allergic rhinitis, atopic dermatitis, allergic conjunctivitis, and anaphylaxis. This review summarizes the biology of LTs and their receptors, recent developments in the area of anti-LT strategies (in settings such as ongoing clinical studies), and prospects for future therapeutic applications.

Highly sensitive and specific LC–MS/MS method to determine endogenous leukotriene B4 levels in human plasma

Aim: To develop a high sensitivity and specific analytical method to measure endogenous levels of leukotriene B4 (LTB4) in human plasma. Methodology: LC–MS/MS and ELISA. Results: An LC–MS/MS method was developed with a sensitivity of 1.0 pg/ml, and within and between batch precision of <16% and <13% RSD, respectively. Conclusion: We have developed a sensitive LC–MS/MS method that can detect endogenous LTB4 in human plasma. The LC–MS/MS method displayed correlation with a commercial LTB4 ELISA when analyzing in ex vivo ionophore-stimulated blood samples. For untreated plasma this correlation was lost. Endogenous LTB4 was shown to be unstable in plasma during storage at -20°C and subject to stereoisomer formation. Neither of the assays could quantify endogenous plasma LTB4 in samples stored for long term.

Urinary Leukotriene E4 as a Biomarker of Exposure, Susceptibility, and Risk in Asthma: An Update

Measurement of urinary leukotriene E₄ (uLTE₄) is a sensitive and noninvasive method of assaying total body cysteinyl leukotriene (CysLT) production and changes in CysLT production. Recent studies have reported on novel LTE4 receptor interactions and genetic polymorphisms causing CysLT variability. The applications of uLTE₄ as a biomarker continue to expand, including evaluation of environmental exposures, asthma severity risk, aspirin sensitivity, predicting atopy in preschool age children, obstructive sleep apnea, and predicting susceptibility to leukotriene receptor antagonists.

Patient stratification and the unmet need in asthma

Asthma is often described as an inflammatory disease of the lungs and in most patients symptomatic treatment with bronchodilators or inhaled corticosteroids is sufficient to control disease. Unfortunately there are a proportion of patients who fail to achieve control despite treatment with the best current treatment. These severe asthma patients have been considered a homogeneous group of patients that represent the unmet therapeutic need in asthma. Many novel therapies have been tested in unselected asthma patients and the effects have often been disappointing, particularly for the highly specific monoclonal antibody-based drugs such as anti-IL-13 and anti-IL-5. More recently, it has become clear that asthma is a syndrome with many different disease drivers. Clinical trials of anti-IL-13 and anti-IL-5 have focused on biomarker-defined patient groups and these trials have driven the clinical progression of these drugs. Work on asthma phenotyping indicates that there is a group of asthma patients where T helper cell type 2 (Th2) cytokines and inflammation predominate and these type 2 high (T2-high) patients can be defined by biomarkers and response to therapies targeting this type of immunity, including anti-IL-5 and anti-IL-13. However, there is still a subset of T2-low patients that do not respond to these new therapies. This T2-low group will represent the new unmet medical need now that the T2-high-targeting therapies have made it to the market. This review will examine the current thinking on patient stratification in asthma and the identification of the T2-high subset. It will also look at the T2-low patients and examine what may be the drivers of disease in these patients.

Effect of prasugrel in patients with asthma: results of PRINA, a randomized, double-blind, placebo-controlled, cross-over study

BACKGROUND

Although experimental studies have demonstrated that platelets are proinflammatory cells, no randomized studies have tested the anti-inflammatory effect of antiplatelet agents in humans. The platelet P2Y12 receptors mediated bronchial inflammation in a mouse model of asthma, suggesting that P2Y12 represents a pharmacologic target for asthma.

OBJECTIVES

In this proof-of concept, placebo-controlled, randomized, cross-over study, we tested the effects of the P2Y12 antagonist prasugrel on bronchial hyperreactivity of asthmatic patients.

PATIENTS/METHODS

Twenty-six asthmatic patients were randomly and blindly allocated to prasugrel (10 mg once daily) or placebo for 15 days. After a ≥ 15-day wash-out, patients were crossed over to the alternative treatment. Before and after each treatment, patients underwent a bronchial provocation test with mannitol and measurement of fractional exhaled nitric oxide (FeNO). Inhibition of P2Y12 -dependent platelet reactivity (platelet reactivity index [PRI]) was measured with the vasodilator-stimulated phosphoprotein phosphorylation assay.

RESULTS

The provocative dose of mannitol causing a 15% drop in forced expiratory volume in 1 s increased from 142 mg (95% confidence interval [CI] 82-202) to 187 mg (95% CI 113-262) after prasugrel treatment (P = 0.09), and did not change after placebo treatment (136 mg [95% CI 76-196] and 144 mg [95% CI 84-204], P = 0.65). FeNO did not change after either treatment. The PRI decreased from 80% (95% CI 77-83) to 23% (95% CI 7-29) after prasugrel treatment (P < 0.001) and remained unchanged after placebo.

CONCLUSIONS

Our proof-of-concept, randomized, controlled study is the first one to test in vivo the anti-inflammatory effects of platelet inhibition in human patients. The results suggest that pharmacologic inhibition of P2Y12 receptors may slightly reduce the bronchial inflammatory burden, and lay the groundwork for further studies, with clinical endpoints.

Biological effects of leukotriene E4 on eosinophils

Studies demonstrate the existence of novel receptors for cysteinyl leukotrienes (CysLTs) that are responsive to leukotriene (LT) E4 and might be pathogenic in asthma. Given the eosinophilic infiltration in this disorder, we investigated eosinophil expression of P2Y12 and gpr99 and their capacity to respond to LTE4. Receptor transcript expression was investigated via quantitative PCR and surface protein expression via flow cytometry. We investigated LTE4 influences on eosinophils including Ca(+2) flux, cAMP induction, modulation of adhesion molecule expression, apoptosis and degranulation. Eosinophils displayed both transcript and surface protein expression of P2Y12 and gpr99. We could not find evidence of LTE4 activation of eosinophils, however, LTE4 induced cAMP expression, and preincubation of eosinophils with LTE4 inhibited degranulation. Even though eosinophils are an important source of CysLTs in AERD, eosinophils are not themselves the pro-inflammatory biological target and, in contrast, LTE4 via cAMP primarily elicits anti-inflammatory responses.

Arachidonic acid metabolites and enzyme transcripts in asthma are altered by cigarette smoking

BACKGROUND

Arachidonic acid metabolites are implicated in the pathogenesis of asthma although only limited information is available on the impact of current smoking history on these metabolites. The aim of the study was to examine the effect of smoking status on urinary, sputum, and plasma eicosanoid concentrations and relevant enzyme transcripts in asthma.

METHODS

In 108 smokers and never smokers with asthma and 45 healthy controls [smokers and never smokers], we measured urinary tetranor prostaglandin (PG)D2 (PGDM) and leukotriene (LT)E4 , induced sputum fluid LTB4 , LTE4 , PGD2 , and PGE2 , plasma secretory phospholipase A2 (sPLA2 ), and 11β prostaglandin F2α (11βPGF2α ), and, in a subgroup with severe asthma, airway leukocyte and epithelial cell mRNA expression levels of arachidonic acid metabolic enzymes.

RESULTS

Smokers with asthma had higher urinary LTE4 ; 83 (59, 130) vs 59 (40, 90) pg/mg creatinine, P = 0.008, and PGDM; 60 (35, 100) vs 41 (28, 59) ng/mg creatinine, P = 0.012 concentrations, respectively, and lower sputum PGE2 concentrations 80 (46, 157) vs 192 (91, 301) pg/ml, P = 0.001 than never smokers with asthma. Sputum LTB4 (P = 0.013), and plasma 11βPGF2α (P = 0.032), concentrations, respectively, were increased in smokers with asthma compared with healthy smokers. Asthma-specific and smoking-related increases (>1.5-fold expression) in arachidonate 15-lipoxygenase and gamma-glutamyltransferase transcripts were demonstrated.

CONCLUSIONS

Several arachidonic acid metabolites and enzyme transcripts involving both lipoxygenase and cyclooxygenase pathways are increased in smokers with asthma and differ from never smokers with asthma. Possibly targeting specific lipoxygenase and cyclooxygenase pathways that are activated by asthma and cigarette smoking may optimize therapeutic responses.

Efficacy, safety and tolerability of GSK2190915, a 5-lipoxygenase activating protein inhibitor, in adults and adolescents with persistent asthma: a randomised dose-ranging study

Background

GSK2190915 is a high affinity 5-lipoxygenase-activating protein inhibitor being developed for the treatment of asthma. The objective of this study was to evaluate GSK2190915 efficacy, dose–response and safety in subjects with persistent asthma treated with short-acting beta2-agonists (SABAs) only.

Methods

Eight-week multicentre, randomised, double-blind, double-dummy, stratified (by age and smoking status), parallel-group, placebo-controlled study in subjects aged ≥12 years with a forced expiratory volume in 1 second (FEV₁) of 50–85% predicted. Subjects (n = 700) were randomised to receive once-daily (QD) oral GSK2190915 (10–300 mg), twice-daily inhaled fluticasone propionate 100 μg, oral montelukast 10 mg QD or placebo. The primary endpoint was mean change from baseline (randomisation) in trough (morning pre-dose and pre-rescue bronchodilator) FEV₁ at the end of the 8-week treatment period. Secondary endpoints included morning and evening peak expiratory flow, symptom-free days and nights, rescue-free days and nights, day and night-time symptom scores, day and night-time rescue medication use, withdrawals due to lack of efficacy, Asthma Control Questionnaire and Asthma Quality of Life Questionnaire scores.

Results

For the primary endpoint, there was no statistically significant difference between any dose of GSK2190915 QD and placebo. However, repeated measures sensitivity analysis demonstrated nominal statistical significance for GSK2190915 30 mg QD compared with placebo (mean difference: 0.115 L [95% confidence interval: 0.00, 0.23], p = 0.044); no nominally statistically significant differences were observed with any of the other doses. For the secondary endpoints, decreases were observed in day-time symptom scores and day-time SABA use for GSK2190915 30 mg QD versus placebo (p ≤ 0.05). No dose–response relationship was observed for the primary and secondary endpoints across the GSK2190915 dose range studied; the 10 mg dose appeared to be sub-optimal. GSK2190915 was associated with a dose-dependent reduction in urinary leukotriene E₄. The profile and incidence of adverse events were similar between treatment groups.

Conclusion

Efficacy was demonstrated for GSK2190915 30 mg compared with placebo in day-time symptom scores and day-time SABA use. No additional improvement on efficacy endpoints was gained by administration of GSK2190915 doses greater than 30 mg. GSK2190915 was well-tolerated. These results may support further studies with GSK2190915 30 mg.

Trial registration

Clinicaltrials.gov: NCT01147744.

Urinary leukotriene E4 as a biomarker of exposure, susceptibility and risk in asthma

Measurement of urinary leukotriene E(4) (uLTE(4)) is a sensitive and noninvasive method of assaying total body cysteinyl leukotriene production and changes in cysteinyl leukotriene production. Recent studies have reported on novel uLTE(4) receptor interactions, and new applications for uLTE(4), as a biomarker of environmental exposure to tobacco smoke and ambient air pollution, a predictor of risk for asthma exacerbations related to tobacco smoke, and a marker of susceptibility to leukotriene receptor antagonists.

Reversed changes of lipoxin A4 and leukotrienes in children with asthma in different severity degree

OBJECTIVES

To investigate the expressions of 15-lipoxygenase (15-LO) and 5-lipoxygenase (5-LO) in leukocytes and the changes of blood lipoxin A(4)(LXA(4)), leukotriene (LT)B(4) and LTC(4) in children with asthma, and to explore the relationship between the blood eicosanoids and one of serum high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-5, IL-8 and IL-13 and IgE in children with asthma.

STUDY DESIGN

One hundred six asthmatic children were divided into three groups, that is, mild persistent asthmatic group, moderate persistent asthmatic group and severe persistent asthmatic group. Forty healthy children were served as controls.

METHODOLOGY

The expressions of 15-LO and 5-LO mRNA in leukocytes were assessed by reverse transcription-polymerase chain reaction, and the blood LXA(4), LTB(4), LTC(4), IL-5, IL-8, and IL-13 were determined with enzyme-linked immunosorbent assay. Serum hsCRP was determined with latex-enhanced immuno-turbidimetry kits.

RESULTS

The leukocytic 15-LO expression and blood LXA(4) were gradually decreased, and the leukocytic 5-LO expression, blood LTB(4), LTC(4), IL-5, IL-8, IL-13, and hsCRP were gradually increased in children with asthma from mild degree to moderate and severe degree. There were positive correlations between blood LXA(4) and one of the peak expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV(1)) percent-predicted values, and negative correlations between blood LTC(4) and one of the PEF and FEV(1) percent-predicted values in children with asthma. There were negative correlations between blood LXA(4) and one of the IL-5, IL-8, IL-13, and hsCRP levels, and positive correlations between one of blood LTB(4), LTC(4) and one of the IL-5, IL-8, IL-13 and hsCRP levels in children with asthma.

CONCLUSIONS

The reversed changes between 15-LO, its product LXA(4) and 5-LO, its products LTB(4) and LTC(4) in children with asthma from mild, moderate to severe degree were found, suggesting that insufficient generation of LXA(4) and overproduction of LTs may be the reason for the asthmatic children whose illness become more serious.

Corticosteroids as inhibitors of cysteinyl leukotriene metabolic and signaling pathways

BACKGROUND

Corticosteroids (CCSs) do not influence secretion of cysteinyl leukotrienes (CysLTs) that occurs on cellular activation during allergic reactions nor do they modulate bronchospastic responses to inhalation challenges with leukotrienes (LTs).

OBJECTIVES

We speculated that CCSs might modulate pathways responsible for CysLT production and diminish the ability of cellular activation to cause their release. Similarly, CCSs could reduce expression of CysLT receptor 1 (CysLTR1) and CysLT receptor 2 (CysLT2R) and modulate their responsiveness.

METHODS

We investigated influences of fluticasone on expression of mRNA for LTC(4) synthase (LTC(4)S), CysLT1R, and CysLT2R within T lymphocytes, monocytes, and eosinophils by means of quantitative PCR. Effects on receptor protein expression were evaluated by means of flow cytometry.

RESULTS

Circulating immune cells (T cells, monocytes, and eosinophils) express low levels of LTC(4)S mRNA, and this was not influenced by CCSs. However, IL-4 induced transcripts in T lymphocytes, and this was prevented by fluticasone. Paradoxically, CCSs synergized with IL-4 to increase LTC(4)S expression in monocytes. Although not influencing basal or IL-4-stimulated CysLT1R expression, fluticasone inhibited basal CysLT2R transcript expression on monocytes and IL-4-induced expression in all 3 cell types.

CONCLUSIONS

In addition to not blocking the acute release of CysLTs on cellular activation, CCSs do not diminish the capacity of cells to synthesize these compounds. CCSs do not diminish CysLT1R expression, consistent with their lack of influence on bronchospasm, which is mediated through this receptor.

Urinary leukotriene E4

Measurement of urinary leukotriene E4 (LTE4) is a sensitive and noninvasive method of assaying total body cysteinyl leukotriene production and changes in cysteinyl leukotriene levels in specific microenvironments, such as the airway. Urinary LTE4 measurements can be used as sensitive biomarkers of exposure to asthma triggers, such as air pollution and viral infections. Recent studies suggest the potential of using urinary LTE4 concentrations as predictors of asthma control and markers of susceptibility to treatment with leukotriene receptor antagonists.

85-kDa cytosolic phospholipase A2 group IValpha gene promoter polymorphisms in patients with severe asthma: a gene expression and case-control study

Cytosolic phospholipase A(2) (cPLA(2)) group IValpha is a critical enzyme involved in the liberation of arachidonic acid from cellular membranes. cPLA(2)(-/-) mice have reduced allergen-induced bronchoconstriction and bronchial hyperresponsiveness. The goal of this study was to investigate polymorphisms of the (CA)(n) and (T)(n) microsatellites and surrounding regions in the cPLA(2)alpha gene promoter. We analysed the cPLA(2) promoter regions containing (CA)(n) and (T)(n) repeats in 87 patients with severe asthma and in 48 control subjects by bidirectional sequencing. Functional studies were performed utilizing reporter genes derived from subjects with varying numbers of these repeats, and on constructs with a series of deletions. We found that the (CA)(n) and (T)(n) regions are polymorphic and that constructs with CA or T repeats or CA and T repeats deleted revealed, respectively, a 41.8 +/- 7%, 22.3 +/- 5% and 100 +/- 20% increase in reporter gene activity. A lower number of CA or T repeats caused higher cPLA(2) promoter luciferase activity. The group of shorter alleles of the (CA)(n) microsatellite region (n = 12-18) (P(cor) = 0.00006), and the group of shorter alleles of (T)(n) repeats region (n = 17-38) (P(cor) = 0.0039) occurred significantly more often in patients with severe asthma. We also found novel SNPs in positions -292 C > G, -185 A > C, -180 T > C and -165 A > C. Two of them were associated with the severe asthma phenotype: -180T allele (P(cor) = 0.03996) and -185 A allele (P(cor) = 0.03966). These results demonstrate that (CA)(n) and (T)(n) repeats may have an influence on cPLA(2) transcription which might play a role in severe asthma pathogenesis.

Severe asthma in adults: what are the important questions?

The term severe refractory asthma (SRA) in adults applies to patients who remain difficult to control despite extensive re-evaluation of diagnosis and management following an observational period of at least 6 months by a specialist. Factors that influence asthma control should be recognized and adequately addressed prior to confirming the diagnosis of SRA. This report presents statements according to the literature defining SRA in order address the important questions. Phenotyping SRA will improve our understanding of mechanisms, natural history, and prognosis. Female gender, obesity, and smoking are associated with SRA. Atopy is less frequent in SRA, but occupational sensitizers are common inducers of new-onset SRA. Viruses contribute to severe exacerbations and can persist in the airways for long periods. Inflammatory cells are in the airways of the majority of patients with SRA and persist despite steroid therapy. The T(H)2 immune process alone is inadequate to explain SRA. Reduced responsiveness to corticosteroids is common, and epithelial cell and smooth muscle abnormalities are found, contributing to airway narrowing. Large and small airway wall thickening is observed, but parenchymal abnormalities may influence airway limitation. Inhaled corticosteroids and bronchodilators are the mainstay of treatment, but patients with SRA remain uncontrolled, indicating a need for new therapies.

Zileuton: clinical implications of 5-Lipoxygenase inhibition in severe airway disease

The 5-Lipoxygenase pathway results in the formation of leukotrienes, including leukotriene B(4) (LTB(4)), 5-oxo-6E,8Z,11Z,14Z-eicosatetranoic acid and the cysteinyl leukotrienes (LTC(4), LTD(4) and LTE(4)) and activates all four leukotriene receptors, BLT1, BLT2, cysLT(1) and cysLT(2). Zileuton is the only commercially available inhibitor of the 5-Lipoxygenase pathway. In a number of clinical trials, zileuton has been shown to improve airway function and inflammation, asthma symptom control and quality of life in asthmatics. Given the important role that leukotrienes play in airway inflammation, zileuton provides an additional therapeutic option in the management of chronic, persistent asthma, particularly those asthmatics with more severe disease. In addition, zileuton has shown promise in a number of other conditions, including upper airway inflammatory conditions, dermatological disease and chronic obstructive pulmonary disease. The development of new formulations, including a controlled release tablet formulation for b.i.d. dosing and an intravenous preparation for acute asthma exacerbations may enhance clinical utility and expand therapeutic indications.

Relationship between urinary cysteinyl leukotriene E4 levels and clinical response to antileukotriene treatment in patients with asthma

The aim of this study was to investigate and identify the relationship between urinary cysteinyl leukotriene E(4) levels and clinical response to antileukotriene treatment in patients with asthma. Forty-eight patients with stable mild to moderate asthma were treated with montelukast in a four-week trail. Asthmatic symptom score, beta(2)-agonist usage, percentage of eosinophil, total serum IgE concentration, forced expiratory volume in the first second (FEV(1)), peak expiratory flow rate (PEFR), and urinary leukotriene E(4) (uLTE(4)) were measured before and after treatment. Clinical response was assessed by the improvement of asthma symptom scores, beta(2)-agonist usage, and FEV(1). Responders were defined as patients who had to fit the following three criteria: a reduction of more than 20% in mean symptom score; a reduction of more than 20% in beta(2)-agonist usage, and a mean improvement of FEV(1) of more than 10% from baseline value. Others were classified as nonresponders. Logistic analysis was used to access the various clinical factors correlated with the clinical response. There were 25 responders and 23 nonresponders. The mean uLTE(4) level from the responders was higher than that from the nonresponders (224.5 +/- 34.4 vs. 175.3 +/- 37.1 pg/mg creatinine, p < 0.05). There was a significant correlation between the clinical response and the uLTE(4) level but not demographic features, percentage of eosinophils, serum IgE concentration, or spirometry (p > 0.05). Subjects with a uLTE(4) level of >/= 200 pg/mg creatinine were 3.5 times more likely to respond to montelukast than those with less than 200 pg/mg creatinine (95% confidence interval [CI] = 1.7-15.8). The uLTE(4) level is closely correlated with antileukotriene treatment. uLTE(4) is a good biomarker for selecting this drug to treat asthma.

Zileuton added to low-dose inhaled beclomethasone for the treatment of moderate to severe persistent asthma

OBJECTIVE

To assess the therapeutic effects of oral zileuton tablets combined with low-dose beclomethasone compared to doubling the dose of beclomethasone, in improving lung function and reducing asthma symptoms.

METHODS

Randomized, active-control, double-blind, parallel, multi-center study of zileuton (400 or 600 mg QID)+200 microg beclomethasone dipropionate (BDP) BID versus placebo+BDP 400 microg BID in asthmatics with baseline FEV(1) percent predicted values between 40% and 80% following a single-blind ICS (BDP 200 microg BID) 2-week run-in. During the 3-month double-blind treatment period, assessments included safety, daytime and nighttime symptoms, acute asthma exacerbations, beta(2)-agonist use, AM and PM peak expiratory flow (PEF) and FEV(1).

RESULTS

The addition of a 5-lipoxygenase (5-LO) inhibitor added to a low-dose of BDP showed no significant difference in FEV(1) compared to doubling the dose of BDP. FEV(1) improved in all 3 treatment groups, with mean increases of 10% with zileuton 600 mg QID+BDP 200 microg BID, 12% with zileuton 400mg QID+BDP 200 microg BID, and 11% with BDP 400 microg BID by study end. Within each treatment group, there were significant improvements in asthma symptoms and AM and PM PEF compared to baseline. No significant differences were observed between groups with regards to salbutamol use, acute asthma exacerbations, the requirement for oral/parenteral corticosteroids and adverse clinical events.

CONCLUSIONS

The addition of a 5-LO inhibitor added to low-dose beclomethasone may be an alternative to higher-doses of ICS in patients unable to achieve sufficient asthma control on low-dose ICS therapy.

Protectin D1 is generated in asthma and dampens airway inflammation and hyperresponsiveness

Protectins are newly identified natural chemical mediators that counter leukocyte activation to promote resolution of inflammation. In this study, we provide the first evidence for protectin D1 (PD1, 10R,17S-dihydroxy-docosa-4Z,7Z,11E,13E,15Z,19Z-hexaenoic acid) formation from docosahexaenoic acid in human asthma in vivo and PD1 counterregulatory actions in allergic airway inflammation. PD1 and 17S-hydroxy-docosahexaenoic acid were present in exhaled breath condensates from healthy subjects. Of interest, levels of PD1 were significantly lower in exhaled breath condensates from subjects with asthma exacerbations. PD1 was also present in extracts of murine lungs from both control animals and those sensitized and aerosol challenged with allergen. When PD1 was administered before aeroallergen challenge, airway eosinophil and T lymphocyte recruitment were decreased, as were airway mucus, levels of specific proinflammatory mediators, including IL-13, cysteinyl leukotrienes, and PGD(2), and airway hyperresponsiveness to inhaled methacholine. Of interest, PD1 treatment after aeroallergen challenge markedly accelerated the resolution of airway inflammation. Together, these findings provide evidence for endogenous PD1 as a pivotal counterregulatory signal in allergic airway inflammation and point to new therapeutic strategies for modulating inflammation in asthmatic lung.

Leukotriene E(4) in urine in patients with asthma and COPD--the effect of smoking habit

Leukotriene E(4) (LTE(4)) is implicated in asthma pathophysiology and possibly in chronic obstructive pulmonary disease (COPD) as one of the causes of persistent bronchoconstriction and mucus hypersecretion. Cigarette smoking stimulates cysteinyl leukotrienes (CysLTs) production. We investigated whether LTE(4) is equally increased in asthma and COPD and whether smoking significantly affects LTE(4) levels. Secondary outcomes involved correlations with inflammatory and functional parameters. We studied 40 patients with COPD [20 smokers], 40 asthmatics [20 smokers] and 30 healthy subjects [15 smokers]. Spirometry (FEV(1)% pred., FEV(1)/FVC) was performed, urine was collected for measurement of LTE(4) and creatinine, induced sputum was collected for differential cell counts and serum for ECP. LTE(4)/creatinine levels (pg/mg) [mean (sd)] were increased in asthmatic patients compared to COPD and controls, [125.6(54.5) vs. 54.5(19) vs. 55.9(18.9)pg/mg, respectively, P<0.0001 for asthma]. Smoking significantly affects LTE(4) levels only in asthmatic patients [164 (48) vs. 87 (26.3), P<0.0001 for smokers]. The only significant correlation was between eosinophils in induced sputum and LTE(4)/creatinine levels in asthmatics. In conclusion, patients with asthma presented higher LTE(4) values compared to normals and patients with COPD. Smoking significantly affects LTE(4) values only in asthmatics indicating a different underlying CysLTs inflammatory process in this condition.

Oral montelukast treatment of preschool-aged children with acute asthma

BACKGROUND

Increased amounts of cysteinyl leukotrienes have been demonstrated in urine samples from asthmatic patients, particularly during exacerbations of asthma. Although the use of leukotriene receptor antagonists has been recommended in the treatment of chronic asthma, no guidelines are available regarding their use in the treatment of acute asthma.

OBJECTIVE

To investigate the safety and effectiveness of a 4-mg tablet of oral montelukast in addition to short-acting beta2-agonist bronchodilator as the initial treatment in mild to moderate asthma exacerbations in children between 2 and 5 years old.

METHODS

Fifty-one patients who were experiencing mild to moderate asthma exacerbation were included in a randomized, double-blind, placebo-controlled, parallel-group study. Each patient received either a 4-mg tablet of montelukast or placebo in addition to inhaled salbutamol and were followed up for 4 hours. The pulmonary index score, respiratory rate, and pulse were determined at baseline and throughout 4 hours after administration.

RESULTS

Compared with placebo, the pulmonary index scores and respiratory rates were significantly lower in the montelukast group starting at 90 minutes (P = .01). This difference persisted at 120, 180, and 240 minutes of the study (P = .008, P = .02, and P = .048, respectively). At the end of the first hour of treatment, oral steroid need was 20.8% and 38.5% in patients randomized to the montelukast and placebo groups, respectively (P = .22). Hospitalization rates were not different between the 2 treatment groups.

CONCLUSION

A single 4-mg tablet of montelukast had the potential to provide additive clinical benefit in mild to moderate acute asthma in preschool-aged children when administered concomitantly with short-acting beta2-agonist bronchodilators as the initial treatment.

Effect of montelukast on exhaled leukotrienes and quality of life in asthmatic patients

STUDY OBJECTIVES

In some patients with asthma treated with inhaled corticosteroids, suppression of inflammation is incomplete. This may be because the effect of corticosteroids on cysteinyl-leukotriene (cys-LT) biosynthesis is limited. Montelukast is a cys-LT antagonist that significantly improves asthma control in corticosteroid-treated asthmatic patients. However, not all patients treated with cys-LT antagonists show a clinical improvement.

DESIGN

We have studied the effect of treatment for 4 weeks with montelukast (10 mg/d) on exhaled cys-LTs and leukotriene B4 (LTB4), exhaled nitric oxide, asthma quality of life (AQL), and respiratory function in patients with stable asthma.

SETTING

Asthma clinics in general practice.

PATIENTS

We studied 50 patients (30 men; mean +/- SEM age, 53 +/- 2 years) who were treated with inhaled corticosteroids.

MEASUREMENTS AND RESULTS

We detected cys-LTs in exhaled breath condensate in 25 of 50 patients; however, in the normal nonasthmatic subjects, cys-LTs were below the limit of detection. After treatment with montelukast, there was a fall in cys-LT concentrations from 14.6 +/- 3.3 to 8.5 +/- 2.6 pg/mL after 2 weeks (p > 0.05) and to 3.9 +/- 1.3 pg/mL after 4 weeks (p < 0.01). Exhaled LTB4 levels were also elevated. After treatment with montelukast, LTB4 levels fell from 33.0 +/- 3.9 to 20.4 +/- 2.5 pg/mL after 2 weeks of treatment (p < 0.05), and to 17.0 +/- 2.2 pg/mL after 4 weeks of treatment (p < 0.01). These changes in exhaled cys-LT and LTB4 were associated with significant improvements in AQL scores.

CONCLUSIONS

It appears that in some patients with stable asthma treated with inhaled corticosteroids, the suppression of inflammation is incomplete. Adding a leukotriene receptor antagonist can provide a complementary effect of controlling inflammation, with a significant improvement in quality of life.

Leukotrienes and isocyanate-induced asthma: a pilot study

BACKGROUND

The role of leukotrienes (LTs) in the pathophysiology of isocyanate-induced asthma is not well known.

OBJECTIVE

We sought to characterize the type of airway inflammation induced by exposure to isocyanates and to investigate whether exposure to isocyanates induced an increase in LT receptor cysteinyl leukotriene ((CysLT)(1), CysLT(2) and leukotriene B(4) receptor (BLT(1))) expression, as well as a release of LT (LTC(4) and leukotriene B(4) (LTB(4))) and IL-8 in both asthmatics with isocyanate-induced asthma and healthy subjects.

METHODS

We investigated eight subjects with isocyanate-induced asthma and eight healthy subjects. Both groups underwent specific inhalation challenges to isocyanates in the laboratory. Induced sputum was collected before and after exposure to isocyanates. CysLT(1), CysLT(2) and BLT(1) expression was assessed by flow cytometry, whereas LTC(4), LTB(4) and IL-8 were measured in the sputum supernatants by enzyme immunoassay.

RESULTS

Exposure to isocyanates induced an increase in sputum neutrophils only in subjects with occupational asthma. There was a significant increase in CysLT(1) and BLT(1) receptor expression, as well as a release of LTB(4) and IL-8 after exposure to isocyanates compared with the baseline, only in subjects with isocyanate-induced asthma, whereas there was no increase in LTC(4). Exposure to isocyanates did not induce any change in LT receptor expression nor in the levels of LTC(4), LTB(4) and IL-8, in healthy subjects.

CONCLUSION

The neutrophilia observed after exposure to isocyanates is likely to be related to the release of LTB(4), probably enhanced by the increased expression of BLT(1) on neutrophils as well as by the release of IL-8. The significance of the increase of CysLT1 receptor expression on neutrophils is unknown and needs further investigation.

Evaluation of oxidative-antioxidative status and the L-arginine-nitric oxide pathway in asthmatic patients

BACKGROUND

Reactive nitrogen, oxygen species and oxidative stress are related to many pulmonary diseases. Nitric oxide (NO) may be involved in either the protection against or the induction of oxidative stress within various tissues. It is derived from the amino acid L-arginine by the action of NO synthase (NOS). L-arginine can also be metabolized by arginase with the production of ornithine and urea. Because of the competition between NOS and arginase for the same substrate, their activities are regulated reciprocally. Therefore, the rate of NO generation associated with oxidative stress is dependent on the relative activities of both NOS and arginase. The objective of this study is to investigate the L-arginine-NO pathway, evaluate oxidative-antioxidative status in the patients with asthma and demonstrate their reciprocal regulation.

METHODS

30 voluntary asthmatic patients and 30 healthy control subjects with similar age range and sex were included in the study. A total of 10 ml venous blood was drawn, plasma and packed erythrocytes were prepared for the biochemical analyses. Plasma arginase activities and NO levels, and erythrocyte malondialdehyde and reduced glutathione levels were detected.

RESULTS

Plasma malondialdehyde levels were significantly higher and glutathione levels were lower in patients with asthma than those of the control subjects (P < 0.001 and P < 0.01, respectively). Arginase activities were significantly lower and NO levels were higher in the patients than those of the controls (P < 0.001 for both). The negative correlation between arginase and NO levels in the patients was significant (r = -0.47; P < 0.01). There was also a positive correlation between malondialdehyde and NO levels in the patients (r = 0.51; P < 0.01).

CONCLUSIONS

The results suggest that the L-arginine-NO pathway is involved in the pathophysiology of asthma; the arginase activities decrease which causes an increase in the L-arginine levels thereby up-regulation of NO production may contribute to the increase of oxidative stress in asthma.