Asthma: defining of the persistent adult phenotypes
ABSTRACT The common disease asthma is probably not a single disease, but rather a complex of multiple, separate syndromes that overlap. Although clinicians have recognised these different phenotypes for many years, they have remained poorly characterised, with little known about the underlying pathobiology contributing to them. Development of targeted therapies for asthma, and phenotype-specific clinical trials have raised interest in these phenotypes. Improved understanding of these phenotypes in complex diseases such as asthma will also improve our ability to link specific genotypes to their associated disease, which should help development of biomarkers. However, there is no standardised method to define asthma phenotypes. This Review analyses some of the methods that have been used to define asthma phenotypes and proposes an integrated method of classification to improve our understanding of these phenotypes.
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ABSTRACT: Background It is important to study differential inflammatory cellular migration, particularly of eosinophils and neutrophils, in asthma and how this is influenced by environmental stimuli such as allergen exposure and the effects of anti asthma therapy. Methods We isolated blood neutrophils and eosinophils from 12 atopic asthmatic human volunteers (Group 1 — four Early Allergic Responders unchallenged (EAR); Group 2 — four Early and Late Allergic Responders (LAR) challenged; Group 3 — four EAR and LAR challenged and treated with systemic corticosteroids) using cGMP CD16 CliniMACS. Cells were isolated prior to allergen challenge where applicable, labelled with 99mTc-HMPAO and then re-infused intravenously. The kinetics of cellular influx/efflux into the lungs and other organs were imaged via scintigraphy over 4 h, starting at 5 to 6 h following allergen challenge where applicable. Results Neutrophils and eosinophils were isolated to a mean (SD) purity of 98.36% (1.09) and 96.31% (3.0), respectively. Asthmatic neutrophils were activated at baseline, mean (SD) CD11bHigh cells 46 (10.50) %. Isolation and radiolabelling significantly increased their activation to > 98%. Eosinophils were not activated at baseline, CD69+ cells 1.9 (0.6) %, increasing to 38 (3.46) % following isolation and labelling. Analysis of the kinetics of net eosinophil and neutrophil lung influx/efflux conformed to a net exponential clearance with respective mean half times of clearance 6.98 (2.18) and 14.01 (2.63) minutes for Group 1, 6.03 (0.72) and 16.04 (2.0) minutes for Group 2 and 5.63 (1.20) and 14.56 (3.36) minutes for Group 3. These did not significantly differ between the three asthma groups (p > 0.05). Conclusions Isolation and radiolabelling significantly increased activation of eosinophils (CD69) and completely activated neutrophils (CD11bHigh) in all asthma groups. Net lung neutrophil efflux was significantly slower than that of eosinophils in all asthma study groups. There was a trend for pre-treatment with systemic corticosteroids to reduce lung retention of eosinophils following allergen challenge.10/2014; 1(1). DOI:10.1016/j.ebiom.2014.10.014
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ABSTRACT: Although not yet widely implemented, fraction of exhaled nitric oxide (FeNO) has emerged in recent years as a potentially useful biomarker for the assessment of airway inflammation both in undiagnosed patients with non-specific respiratory symptoms and in those with established airway disease. Research to date essentially suggests that FeNO measurement facilitates the identification of patients exhibiting T-helper cell type 2 (Th2)-mediated airway inflammation, and effectively those in whom anti-inflammatory therapy, particularly inhaled corticosteroids (ICS), is beneficial. In some studies, FeNO-guided management of patients with established airway disease is associated with lower exacerbation rates, improvements in adherence to anti-inflammatory therapy, and the ability to predict risk of future exacerbations or decline in lung function. Despite these data, concerns regarding the applicability and utility of FeNO in clinical practice still remain. This article reviews the current evidence, both supportive and critical of FeNO measurement, in the diagnosis and management of asthma and other inflammatory airway diseases. It additionally provides suggestions regarding the practical application of FeNO measurement: how it could be integrated into routine clinical practice, how its utility could be assessed and its true value to both clinicians and patients could be established. Although some unanswered questions remain, current evidence suggests that FeNO is potentially a valuable tool for improving the personalised management of inflammatory airway diseases.Respiratory medicine 06/2014; 108(6). DOI:10.1016/j.rmed.2014.02.005 · 2.92 Impact Factor
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ABSTRACT: A previous Genome-Wide Association Study in asthma revealed putative associations that merit further investigation. In this study, the genome-wide significant associations of Single Nucleotide Polymorphisms (SNPs) at the 5% False Discovery Rate were examined in independent groups of severe asthmatics. The panel consisted of 397 severe asthmatic adults, 116 severe asthmatic children and a collection of 207 family-trios with an asthmatic proband. Three SNPs in the PDCD4 gene (rs6585018:G>A, rs1322997:C>A, and rs34104444:G>A) were significantly associated with severe childhood asthma (P values: 0.003, 0.002, 0.004) and total immunoglobulin E (IgE) levels (P values: 0.034, 0.041, 0.052). In an independent group of 234 asthmatic children and 652 controls, PDCD4 SNPs rs1407696:T>G and rs11195360:T>C were associated with total IgE levels (P values: 0.006, 0.014). In silico analysis of PDCD4 locus showed that rs6585018:G>A had the potential to affect MYB transcription factor binding, shown to act as a PDCD4-transcription inducer. Electromobility Shift Assays and reporter assays revealed that rs6585018:G>A alters MYB binding thereby influencing the expression of PDCD4. SNPs within MYB itself confer susceptibility to eosinophilia and asthma. Our association between a variant MYB binding site in PDCD4 and the severest form of childhood asthma therefore suggests that PDCD4 is a novel molecule of importance to asthmatic inflammatory responses. © 2013 This article is protected by copyright. All rights reserved.Human Mutation 08/2013; 34(8). DOI:10.1002/humu.22340 · 5.05 Impact Factor