Rhinitis associated with asthma is distinct from rhinitis alone: The ARIA-MeDALL hypothesis.

Asthma, rhinitis, and atopic dermatitis (AD) are interrelated clinical phenotypes that partly overlap in the human interactome. The concept of "one-airway-one-disease," coined over 20 years ago, is a simplistic approach of the links between upper- and lower-airway allergic diseases. With new data, it is time to reassess the concept. This article reviews (i) the clinical observations that led to Allergic Rhinitis and its Impact on Asthma (ARIA), (ii) new insights into polysensitization and multimorbidity, (iii) advances in mHealth for novel phenotype definitions, (iv) confirmation in canonical epidemiologic studies, (v) genomic findings, (vi) treatment approaches, and (vii) novel concepts on the onset of rhinitis and multimorbidity. One recent concept, bringing together upper- and lower-airway allergic diseases with skin, gut, and neuropsychiatric multimorbidities, is the "Epithelial Barrier Hypothesis." This review determined that the "one-airway-one-disease" concept does not always hold true and that several phenotypes of disease can be defined. These phenotypes include an extreme "allergic" (asthma) phenotype combining asthma, rhinitis, and conjunctivitis. Rhinitis alone and rhinitis and asthma multimorbidity represent two distinct diseases with the following differences: (i) genomic and transcriptomic background (Toll-Like Receptors and IL-17 for rhinitis alone as a local disease; IL-33 and IL-5 for allergic and non-allergic multimorbidity as a systemic disease), (ii) allergen sensitization patterns (mono- or pauci-sensitization versus polysensitization), (iii) severity of symptoms, and (iv) treatment response. In conclusion, rhinitis alone (local disease) and rhinitis with asthma multimorbidity (systemic disease) should be considered as two distinct diseases, possibly modulated by the microbiome, and may be a model for understanding the epidemics of chronic and autoimmune diseases.

The utility of a standardised breath sampler in school age children within a real-world prospective study.

Clinical assessment of children with asthma is problematic, and non-invasive biomarkers are needed urgently. Monitoring exhaled volatile organic compounds (VOCs) is an attractive alternative to invasive tests (blood and sputum) and may be used as frequently as required. Standardised reproducible breath-sampling is essential for exhaled-VOC analysis, and although the ReCIVA (Owlstone Medical Limited) breath-sampler was designed to satisfy this requirement, paediatric use was not in the original design brief. The efficacy of the ReCIVA at sampling breath from children has been studied, and 90 breath-samples from 64 children (5-15 years) with, and without asthma (controls), were collected with two different ReCIVA units. Seventy samples (77.8%) contained the specified 1 l of sampled-breath. Median sampling times were longer in children with acute asthma (770.2 s, range: 532.2-900.1 s) compared to stable asthma (690.6 s, range: 477.5-900.1 s;p= 0.01). The ReCIVA successfully detected operational faults, in 21 samples. A leak, caused by a poor fit of the face mask seal was the most common (15); the others were USB communication-faults (5); and, a single instance of a file-creation error. Paediatric breath-profiles were reliably monitored, however synchronisation of sampling to breathing-phases was sometimes lost, causing some breaths not to be sampled, and some to be sampled continuously. This occurred in 60 (66.7%) of the samples and was a source of variability. Importantly, multi-variate modelling of untargeted VOC analysis indicated the absence of significant batch effects for eight operational variables. The ReCIVA appears suitable for paediatric breath-sampling. Post-processing of breath-sample meta-data is recommended to assess the quality of sample-acquisition. Further, future studies should explore the effect of pump-synchronisation faults on recovered VOC profiles, and mask sizes to fit all ages will reduce the potential for leaks and importantly, provide higher levels of comfort to children with asthma.

Assessing causal treatment effect estimation when using large observational datasets.

BACKGROUND: Recently, there has been a heightened interest in developing and evaluating different methods for analysing observational data. This has been driven by the increased availability of large data resources such as Electronic Health Record (EHR) data alongside known limitations and changing characteristics of randomised controlled trials (RCTs). A wide range of methods are available for analysing observational data. However, various, sometimes strict, and often unverifiable assumptions must be made in order for the resulting effect estimates to have a causal interpretation. In this paper we will compare some common approaches to estimating treatment effects from observational data in order to highlight the importance of considering, and justifying, the relevant assumptions prior to conducting an observational analysis. METHODS: A simulation study was conducted based upon a small cohort of patients with chronic obstructive pulmonary disease. Two-stage least squares instrumental variables, propensity score, and linear regression models were compared under a range of different scenarios including different strengths of instrumental variable and unmeasured confounding. The effects of violating the assumptions of the instrumental variables analysis were also assessed. Sample sizes of up to 200,000 patients were considered. RESULTS: Two-stage least squares instrumental variable methods can yield unbiased treatment effect estimates in the presence of unmeasured confounding provided the sample size is sufficiently large. Adjusting for measured covariates in the analysis reduces the variability in the two-stage least squares estimates. In the simulation study, propensity score methods produced very similar results to linear regression for all scenarios. A weak instrument or strong unmeasured confounding led to an increase in uncertainty in the two-stage least squares instrumental variable effect estimates. A violation of the instrumental variable assumptions led to bias in the two-stage least squares effect estimates. Indeed, these were sometimes even more biased than those from a naïve linear regression model. CONCLUSIONS: Instrumental variable methods can perform better than naïve regression and propensity scores. However, the assumptions need to be carefully considered and justified prior to conducting an analysis or performance may be worse than if the problem of unmeasured confounding had been ignored altogether.

New and emerging drug treatments for severe asthma.

Asthma is a common chronic inflammatory condition of the airways affecting over 300 million people world-wide. In 5%-10% of cases, it is severe, with disproportionate healthcare resource utilization including costs associated with frequent exacerbations and the long-term health effects of systemic steroids. Characterization of inflammatory pathways in severe asthma has led to the development of targeted biological and small molecule therapies which aim to achieve disease control while minimizing corticosteroid-associated morbidity. Herein, we review currently licensed agents and those in development, and speculate how drug therapy for severe asthma might evolve and impact on clinical outcomes in the near future.

The role of oral methotrexate as a steroid sparing agent in refractory eosinophilic asthma.

The use of oral methotrexate for refractory eosinophilic asthma in a tertiary asthma referral centre, Glenfield Hospital, Leicester, was evaluated between January 2006 and December 2014. The patients ( n = 61) were carefully phenotyped at baseline with markers of airway inflammation. In addition, a structured oral methotrexate proforma was utilized to evaluate response to therapy and adverse events. Oral steroid withdrawal was attempted 3 months after commencing treatment. Several outcomes were evaluated at 12 months, including both efficacy and adverse effects; 15% ( n = 9/61) responded by achieving a decrease in daily oral corticosteroid dose (mean 8.43 (±8.76) mg), although we were unable to identify factors that predicted a treatment response. There were no other significant changes in any other clinical outcome measures. There was a high rate of adverse events (19/61 (31%)), primarily gastrointestinal/hepatitis. Our findings support the use of biological agents in preference to using oral methotrexate as a steroid sparing agent at the first instance. In the event of failure of these agents, oral methotrexate remains a therapeutic option, which can be considered in highly specialist severe asthma centres.

Responsiveness to oral prednisolone in severe asthma is related to the degree of eosinophilic airway inflammation.

BACKGROUND: Patients with severe asthma appear relatively corticosteroid resistant. Corticosteroid responsiveness is closely related to the degree of eosinophilic airway inflammation. The extent to which eosinophilic airway inflammation in severe asthma responds to treatment with systemic corticosteroids is not clear. OBJECTIVE: To relate the physiological and inflammatory response to systemic corticosteroids in asthma to disease severity and the baseline extent of eosinophilic inflammation. METHODS: Patients with mild/moderate and severe asthma were investigated before and after 2 weeks of oral prednisolone (Clintrials.gov NCT00331058 and NCT00327197). We pooled the results from two studies with common protocols. The US study contained two independent centres and the UK one independent centre. The effect of oral corticosteroids on FEV1 , Pc20, airway inflammation and serum cytokines was investigated. Baseline measurements were compared with healthy subjects. RESULTS: Thirty-two mild/moderate asthmatics, 50 severe asthmatics and 35 healthy subjects took part. At baseline, both groups of asthmatics had a lower FEV1 and Pc20 and increased eosinophilic inflammation compared to healthy subjects. The severe group had a lower FEV1 and more eosinophilic inflammation compared to mild/moderate asthmatics. Oral prednisolone caused a similar degree of suppression of eosinophilic inflammation in all compartments in both groups of asthmatics. There were small improvements in FEV1 and Pc20 for both mild/ moderate and severe asthmatics with a correlation between the baseline eosinophilic inflammation and the change in FEV1 . There was a ~50% reduction in the serum concentration of CXCL10 (IP-10), CCL22 (MDC), CCL17 (TARC), CCL-2 (MCP-1) and CCL-13 (MCP-4) in both asthma groups after oral corticosteroids. CONCLUSIONS AND CLINICAL RELEVANCE: Disease severity does not influence the response to systemic corticosteroids. The study does not therefore support the concept that severe asthma is associated with corticosteroid resistance. Only baseline eosinophilic inflammation was associated with the physiological response to corticosteroids, confirming the importance of measuring eosinophilic inflammation to guide corticosteroid use.

Myeloid-derived suppressor cell-like fibrocytes are increased and associated with preserved lung function in chronic obstructive pulmonary disease.

BACKGROUND: The role of fibrocytes in chronic obstructive pulmonary disease (COPD) is unknown. We sought to enumerate blood and tissue fibrocytes in COPD and determine the association of blood fibrocytes with clinical features of disease. METHODS: Utilizing flow cytometry to identify circulating, collagen type 1+ cells, we found two populations: (i) CD45+ CD34+ (fibrocytes) and (ii) CD45+ CD34- [myeloid-derived suppressor cell (MDSC)-like fibrocytes] cells in stable COPD (n = 41) and control (n = 29) subjects. Lung resection material from a separate group of subjects with (n = 11) or without (n = 11) COPD was collected for tissue fibrocyte detection. We examined circulating fibrocyte populations for correlations with clinical parameters including quantitative computed tomography (qCT) and determined pathways of association between correlated variables using a path analysis model. RESULTS: Blood and tissue fibrocytes were not increased compared to control subjects nor were blood fibrocytes associated with lung function or qCT, but were increased in eosinophilic COPD. Myeloid-derived suppressor cell-like fibrocytes were increased in COPD compared to controls [2.3 (1.1-4.9), P = 0.038]. Our path analysis model showed that collagen type 1 intensity for MDSC-like fibrocytes was positively associated with lung function through associations with air trapping, predominately in the upper lobes. CONCLUSION: We have demonstrated that two circulating populations of fibrocyte exist in COPD, with distinct clinical associations, but are not prevalent in proximal or small airway tissue. Blood MDSC-like fibrocytes, however, are increased and associated with preserved lung function through a small airway-dependent mechanism in COPD.

IL-33 drives airway hyper-responsiveness through IL-13-mediated mast cell: airway smooth muscle crosstalk.

BACKGROUND: Mast cell localization within the airway smooth muscle (ASM)-bundle plays an important role in the development of airway hyper-responsiveness (AHR). Genomewide association studies implicate the 'alarmin' IL-33 in asthma, but its role in mast cell-ASM interactions is unknown. OBJECTIVES: We examined the expression and functional role of IL-33 in bronchial biopsies of patients with and without asthma, ex vivo ASM, mast cells, cocultured cells and in a mouse model system. METHODS: IL-33 protein expression was assessed in human bronchial tissue from 9 healthy controls, and 18 mild-to-moderate and 12 severe asthmatic patients by immunohistochemistry. IL-33 and ST2 mRNA and protein expression in human-derived ASM, epithelial and mast cells were assessed by qPCR, immunofluorescence and/or flow cytometry and ELISA. Functional assays were used to assess calcium signalling, wound repair, proliferation, apoptosis and contraction. AHR and inflammation were assessed in a mouse model. RESULTS: Bronchial epithelium and ASM expressed IL-33 with the latter in asthma correlating with AHR. ASM and mast cells expressed intracellular IL-33 and ST2. IL-33 stimulated mast cell IL-13 and histamine secretion independent of FcεR1 cross-linking and directly promoted ASM wound repair. Coculture of mast cells with ASM activated by IL-33 increased agonist-induced ASM contraction, and in vivo IL-33 induced AHR in a mouse cytokine installation model; both effects were IL-13 dependent. CONCLUSION: IL-33 directly promotes mast cell activation and ASM wound repair but indirectly promotes ASM contraction via upregulation of mast cell-derived IL-13. This suggests that IL-33 may present an important target to modulate mast cell-ASM crosstalk in asthma.

A novel electrospun biphasic scaffold provides optimal three-dimensional topography for in vitro co-culture of airway epithelial and fibroblast cells.

Conventional airway in vitro models focus upon the function of individual structural cells cultured in a two-dimensional monolayer, with limited three-dimensional (3D) models of the bronchial mucosa. Electrospinning offers an attractive method to produce defined, porous 3D matrices for cell culture. To investigate the effects of fibre diameter on airway epithelial and fibroblast cell growth and functionality, we manipulated the concentration and deposition rate of the non-degradable polymer polyethylene terephthalate to create fibres with diameters ranging from nanometre to micrometre. The nanofibre scaffold closely resembles the basement membrane of the bronchiole mucosal layer, and epithelial cells cultured at the air-liquid interface on this scaffold showed polarized differentiation. The microfibre scaffold mimics the porous sub-mucosal layer of the airway into which lung fibroblast cells showed good penetration. Using these defined electrospinning parameters we created a biphasic scaffold with 3D topography tailored for optimal growth of both cell types. Epithelial and fibroblast cells were co-cultured onto the apical nanofibre phase and the basal microfibre phase respectively, with enhanced epithelial barrier formation observed upon co-culture. This biphasic scaffold provides a novel 3D in vitro platform optimized to mimic the different microenvironments the cells encounter in vivo on which to investigate key airway structural cell interactions in airway diseases such as asthma.

Integrated care pathways for airway diseases (AIRWAYS-ICPs).

The objective of Integrated Care Pathways for Airway Diseases (AIRWAYS-ICPs) is to launch a collaboration to develop multi-sectoral care pathways for chronic respiratory diseases in European countries and regions. AIRWAYS-ICPs has strategic relevance to the European Union Health Strategy and will add value to existing public health knowledge by: 1) proposing a common framework of care pathways for chronic respiratory diseases, which will facilitate comparability and trans-national initiatives; 2) informing cost-effective policy development, strengthening in particular those on smoking and environmental exposure; 3) aiding risk stratification in chronic disease patients, using a common strategy; 4) having a significant impact on the health of citizens in the short term (reduction of morbidity, improvement of education in children and of work in adults) and in the long-term (healthy ageing); 5) proposing a common simulation tool to assist physicians; and 6) ultimately reducing the healthcare burden (emergency visits, avoidable hospitalisations, disability and costs) while improving quality of life. In the longer term, the incidence of disease may be reduced by innovative prevention strategies. AIRWAYSICPs was initiated by Area 5 of the Action Plan B3 of the European Innovation Partnership on Active and Healthy Ageing. All stakeholders are involved (health and social care, patients, and policy makers).

CCL2 release by airway smooth muscle is increased in asthma and promotes fibrocyte migration.

BACKGROUND: Asthma is characterized by variable airflow obstruction, airway inflammation, airway hyper-responsiveness and airway remodelling. Airway smooth muscle (ASM) hyperplasia is a feature of airway remodelling and contributes to bronchial wall thickening. We sought to investigate the expression levels of chemokines in primary cultures of ASM cells from asthmatics vs healthy controls and to assess whether differentially expressed chemokines (i) promote fibrocyte (FC) migration towards ASM and (ii) are increased in blood from subjects with asthma and in sputum samples from those asthmatics with bronchial wall thickening. METHODS: Chemokine concentrations released by primary ASM were measured by MesoScale Discovery platform. The chemokine most highly expressed by ASM from asthmatics compared with healthy controls was confirmed by ELISA, and expression of its cognate chemokine receptor by FCs was examined by immunofluorescence and flow cytometry. The role of this chemokine in FC migration towards ASM was investigated by chemotaxis assays. RESULTS: Chemokine (C-C motif) ligand 2 (CCL2) levels were increased in primary ASM supernatants from asthmatics compared with healthy controls. CCR2 was expressed on FCs. Fibrocytes migrated towards recombinant CCL2 and ASM supernatants. These effects were inhibited by CCL2 neutralization. CCL2 levels were increased in blood from asthmatics compared with healthy controls, and sputum CCL2 was increased in asthmatics with bronchial wall thickening. CONCLUSIONS: Airway smooth muscle-derived CCL2 mediates FC migration and potentially contributes to the development of ASM hyperplasia in asthma.

Human airway smooth muscle maintain in situ cell orientation and phenotype when cultured on aligned electrospun scaffolds.

Human airway smooth muscle (HASM) contraction plays a central role in regulating airway resistance in both healthy and asthmatic bronchioles. In vitro studies that investigate the intricate mechanisms that regulate this contractile process are predominantly conducted on tissue culture plastic, a rigid, 2D geometry, unlike the 3D microenvironment smooth muscle cells are exposed to in situ. It is increasingly apparent that cellular characteristics and responses are altered between cells cultured on 2D substrates compared with 3D topographies. Electrospinning is an attractive method to produce 3D topographies for cell culturing as the fibers produced have dimensions within the nanometer range, similar to cells' natural environment. We have developed an electrospun scaffold using the nondegradable, nontoxic, polymer polyethylene terephthalate (PET) composed of uniaxially orientated nanofibers and have evaluated this topography's effect on HASM cell adhesion, alignment, and morphology. The fibers orientation provided contact guidance enabling the formation of fully aligned sheets of smooth muscle. Moreover, smooth muscle cells cultured on the scaffold present an elongated cell phenotype with altered contractile protein levels and distribution. HASM cells cultured on this scaffold responded to the bronchoconstrictor bradykinin. The platform presented provides a novel in vitro model that promotes airway smooth muscle cell development toward a more in vivo-like phenotype while providing topological cues to ensure full cell alignment.

Clinical significance of small airway obstruction markers in patients with asthma.

BACKGROUND: The role of small airway obstruction in the clinical expression of asthma is incompletely understood. OBJECTIVE: We tested the hypotheses that markers of small airway obstruction are associated with (i) increased asthma severity, (ii) impaired asthma control and quality of life and (iii) frequent exacerbations. METHODS: Seventy-four adults with asthma and 18 healthy control subjects underwent impulse oscillometry (IOS), multiple breath inert gas washout (MBW), body plethysmography, single-breath determination of carbon monoxide uptake and spirometry. Patients completed the six-point Asthma Control Questionnaire (ACQ-6) and standardized Asthma Quality of Life Questionnaire [AQLQ(S)]. Asthma severity was classified according to the Global Initiative for Asthma (GINA) treatment steps. RESULTS: The putative small airway obstruction markers Sacin , resistance at 5 Hz minus resistance at 20 Hz (R5-R20) and reactance area (AX) were not independently associated with asthma severity, control, quality of life or exacerbations. In contrast, markers of total (R5) and mean airway resistance of large and small airways (R20) were significantly higher in the severe asthma group compared with the mild-moderate group (0.47 vs. 0.37, P < 0.05 for R5; 0.39 vs. 0.31, P < 0.01 for R20). The strongest independent contributors to ACQ-6 score were R20 and forced expiratory volume in one second (% pred.), and the strongest independent contributors to AQLQ(S) score were R20 and forced vital capacity (% pred.). A history of one or more exacerbations within the previous year was independently associated with R20. CONCLUSIONS AND CLINICAL RELEVANCE: Previously reported markers of small airway obstruction do not appear to be independently associated with asthma disease expression. In contrast, the IOS parameter R20, a marker of mean airway resistance of both large and small airways, appears to have independent clinical significance. These observations require confirmation in prospective longitudinal studies.

Biomarkers that predict and guide therapy for exacerbations of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease. COPD exacerbations have a major impact on morbidity and mortality. The etiology of COPD exacerbations is largely due to viral and bacterial infections in combination with underlying inflammation that is typically neutrophilic, although it is eosinophilic in 10 to 25% of cases. We review the recent studies that have defined novel biological clusters at exacerbation events and consequently identified important biomarkers to direct therapy. These biomarkers include C-reactive protein, procalcitonin, and peripheral blood eosinophil count, which are readily available. We are therefore at a point of making personalized antibiotic and corticosteroid therapy in COPD exacerbations a reality. Integration of the wealth of emerging data to further define the complexity of exacerbations also promises to identify new targets and biomarkers to treat COPD exacerbations.

Genome-wide association study to identify genetic determinants of severe asthma.

BACKGROUND: The genetic basis for developing asthma has been extensively studied. However, association studies to date have mostly focused on mild to moderate disease and genetic risk factors for severe asthma remain unclear. OBJECTIVE: To identify common genetic variants affecting susceptibility to severe asthma. METHODS: A genome-wide association study was undertaken in 933 European ancestry individuals with severe asthma based on Global Initiative for Asthma (GINA) criteria 3 or above and 3346 clean controls. After standard quality control measures, the association of 480 889 genotyped single nucleotide polymorphisms (SNPs) was tested. To improve the resolution of the association signals identified, non-genotyped SNPs were imputed in these regions using a dense reference panel of SNP genotypes from the 1000 Genomes Project. Then replication of SNPs of interest was undertaken in a further 231 cases and 1345 controls and a meta-analysis was performed to combine the results across studies. RESULTS: An association was confirmed in subjects with severe asthma of loci previously identified for association with mild to moderate asthma. The strongest evidence was seen for the ORMDL3/GSDMB locus on chromosome 17q12-21 (rs4794820, p=1.03×10((-8)) following meta-analysis) meeting genome-wide significance. Strong evidence was also found for the IL1RL1/IL18R1 locus on 2q12 (rs9807989, p=5.59×10((-8)) following meta-analysis) just below this threshold. No novel loci for susceptibility to severe asthma met strict criteria for genome-wide significance. CONCLUSIONS: The largest genome-wide association study of severe asthma to date was carried out and strong evidence found for the association of two previously identified asthma susceptibility loci in patients with severe disease. A number of novel regions with suggestive evidence were also identified warranting further study.

Isolation of filamentous fungi from sputum in asthma is associated with reduced post-bronchodilator FEV1.

BACKGROUND: Fungal sensitization is common in severe asthma, but the clinical relevance of this and the relationship with airway colonization by fungi remain unclear. The range of fungi that may colonize the airways in asthma is unknown. OBJECTIVE: To provide a comprehensive analysis on the range of filamentous fungi isolated in sputum from people with asthma and report the relationship with their clinico-immunological features of their disease. METHODS: We recruited 126 subjects with a diagnosis of asthma, 94% with moderate-severe disease, and 18 healthy volunteers. At a single stable visit, subjects underwent spirometry; sputum fungal culture and a sputum cell differential count; skin prick testing to both common aeroallergens and an extended fungal panel; specific IgE to Aspergillus fumigatus. Fungi were identified by morphology and species identity was confirmed by sequencing. Four patients had allergic bronchopulmonary aspergillosis. RESULTS: Forty-eight percent of asthma subjects were IgE-sensitized to one fungal allergen and 22% to ≥ 2. Twenty-seven different taxa of filamentous fungi were isolated from 54% of their sputa, more than one species being detected in 17%. This compared with 3 (17%) healthy controls culturing any fungus (P < 0.01). Aspergillus species were most frequently cultured in isolation followed by Penicillium species. Post-bronchodilator FEV (1) (% predicted) in the subjects with asthma was 71(± 25) in those with a positive fungal culture vs. 83 (± 25) in those culture-negative, (P < 0.01). CONCLUSION AND CLINICAL RELEVANCE: Numerous thermotolerant fungi other than A. fumigatus can be cultured from sputum of people with moderate-to-severe asthma; a positive culture is associated with an impaired post-bronchodilator FEV (1) , which might be partly responsible for the development of fixed airflow obstruction in asthma. Sensitization to these fungi is also common.

Severe chronic allergic (and related) diseases: a uniform approach--a MeDALL--GA2LEN--ARIA position paper.

Concepts of disease severity, activity, control and responsiveness to treatment are linked but different. Severity refers to the loss of function of the organs induced by the disease process or to the occurrence of severe acute exacerbations. Severity may vary over time and needs regular follow-up. Control is the degree to which therapy goals are currently met. These concepts have evolved over time for asthma in guidelines, task forces or consensus meetings. The aim of this paper is to generalize the approach of the uniform definition of severe asthma presented to WHO for chronic allergic and associated diseases (rhinitis, chronic rhinosinusitis, chronic urticaria and atopic dermatitis) in order to have a uniform definition of severity, control and risk, usable in most situations. It is based on the appropriate diagnosis, availability and accessibility of treatments, treatment responsiveness and associated factors such as comorbidities and risk factors. This uniform definition will allow a better definition of the phenotypes of severe allergic (and related) diseases for clinical practice, research (including epidemiology), public health purposes, education and the discovery of novel therapies.

Profiling of sputum inflammatory mediators in asthma and chronic obstructive pulmonary disease.

BACKGROUND: Asthma and chronic obstructive pulmonary disease (COPD) display features of overlap in airway physiology and airway inflammation. Whether inflammatory phenotypes in airway disease describe similar mediator expression is unknown. OBJECTIVES: To explore the relationship of airway inflammation and cytokine and chemokine expression in asthma and COPD. METHODS: Subjects with asthma and COPD (n = 54 and n = 49) were studied. Clinical characteristics and sputum were collected at entry into the study. A 2-step sputum processing method was performed for supernatant and cytospin preparation. Meso Scale Discovery and Luminex platforms were used to measure cytokines, chemokines and matrix metalloproteinase levels. RESULTS: Analytes sensitive to dithiothreitol (DTT) that had increased recovery in the 2-step sputum process were IL-1ß, 4, 5, 10, 13, IFN-γ, TNFRI, GM-CSF, CCL2, 3, 4, 5, 13 and 17. There was a differential expression in IL-8, TNFRI and TNFRII between asthma and COPD [mean fold difference (95% CI): IL-8, 2.6 (1.3-5.4), p = 0.01; TNFRI, 2.1 (1.3-5.4), p = 0.03; TNFRII, 2.6 (1.2-5.6), p = 0.02]. In neutrophilic and eosinophilic airway inflammation, TNFα, TNFRI, TNFRII, IL-6, IL-8 and IL-5 could differentiate between these phenotypes. However, these phenotypes were unrelated to the diagnosis of asthma or COPD. CONCLUSION: Recovery of sputum mediators sensitive to DTT can be improved using the described sputum processing technique. Within airway inflammatory sub-phenotypes there is a differential pattern of mediator expression that is independent of disease. Whether these inflammatory phenotypes in asthma and COPD confer distinct pathogeneses, therapeutic responses and clinical phenotypes needs to be further evaluated.