Traditional and patient-centred outcomes with three classes of asthma medication.

Reddel HK.

Woolcock Institute of Medical Research, PO Box M77, Missenden Road, Camperdown, New South Wales 2050, Australia. crj woolcock.org.au.

Lung function is commonly used as the primary endpoint in asthma clinical trials, but it may not reflect changes which are important to patients. The present study compared changes in, and relationships between, traditional and patient-centred end-points during treatment with three classes of asthma medication. Subjects with mild-to-moderate asthma were randomised to double-blind, double-dummy crossover treatment with eformoterol 12 microg b.i.d. or montelukast 10 mg q.d., then single-blind treatment with fluticasone 250 microg b.i.d./placebo capsules, with 6-week treatment periods and 1-week washouts. Individual "traditional" end-points (symptoms, reliever use, forced expiratory volume in one second per cent predicted, morning peak expiratory flow, airway hyperresponsiveness) and "patient-centred" end-points (asthma control questionnaire, quality of life, patient global assessments) were assessed. Principal component analysis and linear modelling were used to explore overall rank orders for treatment, and relationships between outcomes. A total of 58 subjects were randomised. The rank order of benefit from eformoterol and fluticasone differed for three factors derived from principal component analysis (eformoterol>fluticasone for symptom/reliever use factor, fluticasone>eformoterol for lung function factor, eformoterol = fluticasone for patient-centred factor). Montelukast was ranked third for all three factors. A significant relationship between patient-based variables and lung function was found only for montelukast treatment. In asthma treatment, traditional end-points do not fully capture patient-centred benefits, and the relationship between end-points differs with medication class.

Online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15994387&dopt=Abstract montelukast, Singulair




Characterization of the human cysteinyl leukotriene CysLT1 receptor.

Evans JF.

Department of Pharmacology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

The cysteinyl leukotrienes-leukotriene C4(LTC4), leukotriene D4(LTD4) and leukotriene E4(LTE4)-are important mediators of human bronchial asthma. Pharmacological studies have determined that cysteinyl leukotrienes activate at least two receptors, designated CysLT1 and CysLT2. The CysLT1-selective antagonists, such as montelukast (Singulair), zafirlukast (Accolate) and pranlukast (Onon), are important in the treatment of asthma. Previous biochemical characterization of CysLT1 antagonists and the CysLT1 receptor has been in membrane preparations from tissues enriched for this receptor. Here we report the molecular and pharmacological characterization of the cloned human CysLT1 receptor. We describe the functional activation (calcium mobilization) of this receptor by LTD4 and LTC4, and competition for radiolabelled LTD4 binding to this receptor by the cysteinyl leukotrienes and three structurally distinct classes of CysLT1-receptor antagonists. We detected CysLT1-receptor messenger RNA in spleen, peripheral blood leukocytes and lung. In normal human lung, expression of the CysLT1-receptor mRNA was confined to smooth muscle cells and tissue macrophages. Finally, we mapped the human CysLT1-receptor gene to the X chromosome.

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Identification, molecular cloning, expression, and characterization of a cysteinyl leukotriene receptor.

Hay DW.

Department of Pulmonary Pharmacology, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania, USA.

The cysteinyl leukotrienes (CysLTs) have been implicated in the pathophysiology of inflammatory disorders, in particular asthma, for which the CysLT receptor antagonists pranlukast, zafirlukast, and montelukast, have been introduced recently as novel therapeutics. Here we report on the molecular cloning, expression, localization, and pharmacological characterization of a CysLT receptor (CysLTR), which was identified by ligand fishing of orphan seven-transmembrane-spanning, G protein-coupled receptors. This receptor, expressed in human embryonic kidney (HEK)-293 cells responded selectively to the individual CysLTs, LTC(4), LTD(4), or LTE(4), with a calcium mobilization response; the rank order potency was LTD(4) (EC(50) = 2.5 nM) > LTC(4) (EC(50) = 24 nM) > LTE(4) (EC(50) = 240 nM). Evidence was provided that LTE(4) is a partial agonist at this receptor. [(3)H]LTD(4) binding and LTD(4)-induced calcium mobilization in HEK-293 cells expressing the CysLT receptor were potently inhibited by the structurally distinct CysLTR antagonists pranlukast, montelukast, zafirlukast, and pobilukast; the rank order potency was pranlukast = zafirlukast > montelukast > pobilukast. LTD(4)-induced calcium mobilization in HEK-293 cells expressing the CysLT receptor was not affected by pertussis toxin, and the signal appears to be the result of the release from intracellular stores. Localization studies indicate the expression of this receptor in several tissues, including human lung, human bronchus, and human peripheral blood leukocytes. The discovery of this receptor, which has characteristics of the purported CysLT(1) receptor subtype, should assist in the elucidation of the pathophysiological roles of the CysLTs and in the identification of additional receptor subtypes.

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Effects of ONO-1078 (pranlukast) on cytokine production in peripheral blood mononuclear cells of patients with bronchial asthma.

Nakajima S.

Fourth Department of Internal Medicine, Kinki University, School of Medicine, Osaka, Japan.

BACKGROUND: ONO-1078 (pranlukast) is a leukotriene receptor antagonist developed in Japan. This drug has been shown to be useful in oral treatment of bronchial asthma. The present study was undertaken to assess the effects of this drug on the production of cytokines in the peripheral blood mononuclear cells of patients with asthma under stimulation with specific antigens. METHODS: Peripheral blood mononuclear cells from mite antigen-positive asthmatic patients (immunoglobulin E RAST score > 3) were incubated for 72 h in the presence of mite antigen (10 microg/mL). The supernatant of the culture was subjected to enzyme-linked immunosorbent assay (ELISA) to quantify interleukin (IL) -4, IL-3, IL-5, and granulocyte macrophage-colony stimulating factor (GM-CSF). Other peripheral blood mononuclear cells from the same patients were incubated for 72 h in the presence of both mite antigen (10 microg/mL) and ONO-1078 (0.5, 1, or 10 microg/mL), followed by ELISA of the supernatant to quantify the cytokines. RESULTS: Production of IL-4, IL-5, and GM-CSF by mononuclear cells under stimulation with mite antigen was markedly suppressed when they were exposed to ONO-1078 at a concentration of 10 microg/mL. CONCLUSION: The results suggest that ONO-1078 acts directly on peripheral blood mononuclear cells and that blockade of leukotriene receptors on blood mononuclear cells by the cysteinyl-leukotriene receptor antagonist (LTRA) pranlukast (ONO-1078) can dose-dependently inhibit release of immunoreactive TH2-type cytokines (IL-3, IL-4, GM-CSF, and possibly IL-5), but not of the TH1-type cytokine IL-2, when stimulated by mite allergen in vitro. The data may provide clues to the mechanism by which a number of LTRA including zafirulukast and montelukast can reduce airway, sputum and blood eosinophil counts in clinical asthma. It supports animal studies showing that anti-IL-5 antibodies partially block cys-LT-induced airway eosinophilia, suggesting that cys-LTs may cause secondary release of IL-5 from an unknown cell-type. These findings indicate that ONO-1078 suppresses the production of IL-4 (a cytokine that affects IgG antibody production), IL-5, and GM-CSF (cytokines that affect eosinophil activation) by peripheral blood mononuclear cells under stimulation with specific antigens in patients with bronchial asthma. Because of its anti-inflammatory effects, ONO-1078 should be useful in the treatment of bronchial asthma.

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Montelukast, a leukotriene receptor antagonist, inhibits the late airway response to antigen, airway eosinophilia, and IL-5-expressing cells in Brown Norway rats.

Hamid Q.

Meakins-Christie Laboratories and Montreal Chest Institute Research Center, McGill University, Montreal, Quebec, Canada.

BACKGROUND: Asthma is characterized by airflow obstruction, inflammatory cell infiltration, and the synthesis of mediators, such as T(H2) cytokines and leukotrienes, in the airways. Cysteinyl leukotriene (cysLT) receptor antagonists have recently been associated with clinical improvement of asthma and reduced airway inflammation. Whether the beneficial effects of cysLT antagonists are mediated through the modulation of cytokine expression has not been determined. OBJECTIVE: The aim of the study was to determine the presence of eosinophils and IL-5 messenger (m)RNA(+) cells within the lungs of antigen-challenged Brown Norway rats after treatment with the cysLT(1) receptor antagonist montelukast (MK). METHODS: Ovalbumin-sensitized Brown Norway rats were treated with either MK or saline before ovalbumin challenge. Pulmonary mechanics were monitored for 8 hours. Subsequently, immunocytochemistry and in situ hybridization were used to examine bronchoalveolar lavage (BAL) fluid and lung tissue for cells expressing major basic protein (eosinophils) and IL-5 mRNA, respectively. Simultaneous in situ hybridization and immunocytochemistry was used to phenotype the cells expressing mRNA encoding IL-5. RESULTS: Animals treated with MK had significantly lower lung resistance and fewer eosinophils and IL-5 mRNA(+) cells within BAL fluid and lung tissue compared with that found in saline-treated animals. Colocalizaton studies revealed that the majority of IL-5 mRNA(+) cells were T cells and that the number of IL-5 mRNA(+)/CD3(+) or IL-5 mRNA(+)/major basic protein(+) cells were significantly less within BAL from animals treated with MK than from those treated with saline. CONCLUSIONS: These results indicate that the cysLT(1) receptor antagonist MK can diminish the pulmonary response to antigen, tissue eosinophilia, and the number of cells expressing IL-5 mRNA, suggesting that leukotrienes may also regulate the allergic response through the modulation of inflammation and cytokine synthesis.

Online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10588994&dopt=Abstract montelukast, Singulair