Asthma and irreversible airflow obstruction

Effect of Tezepelumab on Lung Function in Patients With Severe, Uncontrolled Asthma in the Phase 3 NAVIGATOR Study

INTRODUCTION

Severe asthma is associated with airway inflammation and airway obstruction. In the phase 3 NAVIGATOR study, tezepelumab treatment significantly improved pre-bronchodilator forced expiratory volume in 1 s (FEV1) compared with placebo in patients with severe, uncontrolled asthma. This analysis assessed the effect of tezepelumab versus placebo on additional lung function parameters in patients from NAVIGATOR.

METHODS

NAVIGATOR was a multicenter, randomized, double-blind, placebo-controlled study. Patients (12-80 years old) receiving medium- or high-dose inhaled corticosteroids and at least one additional controller medication, with or without oral corticosteroids, were randomized 1:1 to tezepelumab 210 mg or placebo subcutaneously every 4 weeks for 52 weeks. Changes from baseline to week 52 in pre-bronchodilator FEV1, post-bronchodilator FEV1, forced vital capacity (FVC), pre-bronchodilator FEV1/FVC ratio, pre-bronchodilator forced expiratory flow between 25 and 75% of vital capacity (FEF25-75), and morning and evening peak expiratory flow (PEF) were assessed.

RESULTS

Tezepelumab treatment improved all evaluated lung function parameters over 52 weeks compared with placebo [least-squares mean difference (95% confidence interval): pre-bronchodilator FEV1, 0.13 (0.08, 0.18) L; post-bronchodilator FEV1, 0.12 (0.07, 0.16) L; FVC, 0.13 (0.07, 0.19) L; FEV1/FVC ratio, 2.06% (1.22%, 2.90%); FEF25-75, 0.13 (0.07, 0.19) L/s; morning PEF, 16.6 (8.1, 25.1) L/min; and evening PEF, 14.9 (6.3, 23.4) L/min]. Improvements were observed as early as weeks 1-2 and were maintained over 52 weeks. Greater improvements in lung function compared with placebo were observed in patients with a disease duration of less than 20 years, those with baseline post-bronchodilator FEV1 reversibility of at least 20%, and in patients with a baseline post-bronchodilator FEV1/FVC ratio of less than 0.7.

CONCLUSION

These findings further support the benefits of tezepelumab treatment in improving airflow limitation in patients with severe, uncontrolled asthma.

CLINICAL TRIAL REGISTRATION

NAVIGATOR (NCT03347279).

Oscillometry and Asthma Control in Patients With and Without Fixed Airflow Obstruction

BACKGROUND

Asthma is defined by the presence of reversible airflow limitation, yet persistently abnormal spirometry may develop despite appropriate asthma treatment. Fixed airflow obstruction (FAO) describes abnormal postbronchodilator spirometry that is associated with greater symptom burden and disease severity. Respiratory oscillometry measures the mechanics of the entire airway tree, including peripheral airway changes that have been shown to influence asthma symptoms.

OBJECTIVE

To evaluate the relationship between abnormal oscillometry following bronchodilator and symptom control in adults with asthma.

METHODS

A prospective cohort of patients with asthma attending an airways clinic completed oscillometry (resistance and reactance), spirometry, and the Asthma Control Test. Postbronchodilator lung function below the lower limit of normal was considered abnormal. Spirometric FAO was defined as FEV₁/forced vital capacity below the lower limit of normal. Spearman's rank coefficient and multiple linear regression were performed to assess associations of lung function parameters with Asthma Control Test. The discriminative ability of abnormal lung function to identify poor asthma control was determined using Cohen's kappa.

RESULTS

Ninety patients with asthma were included; 48% had spirometric FAO. Only reactance parameters, not spirometry, significantly related to (r_s ≥ 0.315; P < .05) and identified asthma control (r² = 0.236; P < .001). Lung function was more strongly associated with asthma control in patients with FAO compared with those without. Abnormal oscillometry identified an additional 24% of patients with poor asthma control as compared with spirometric FAO.

CONCLUSIONS

Reactance related to asthma control, independently of spirometric FAO. Abnormal postbronchodilator reactance identified more patients with poor asthma control compared with spirometry. These findings confirm that oscillometry is a relevant lung function test in the clinical assessment of asthma.

What Is Asthma Chronic Obstructive Pulmonary Disease Overlap?

The term asthma chronic obstructive pulmonary disease (COPD) overlap (ACO) has been popularized to describe people who simultaneously have features of both diseases. Analysis of the basis of disease classification and comparison of the clinical, pathophysiological, and therapeutic features of asthma and COPD concludes that it is not useful to use the term ACO. Rather, it is important to make the individual diagnoses, recognizing that both diseases may coexist. If a concurrent diagnosis of COPD is suspected in people with asthma, pharmacotherapy should primarily follow asthma guidelines, but pharmacologic and nonpharmacologic approaches also may be needed for COPD.

FEV1 decline in relation to blood eosinophils and neutrophils in a population-based asthma cohort

Background

The relationship between lung function decline and eosinophils and neutrophils has important therapeutic implications among asthmatics, but it has rarely been studied in large cohort studies.

Objective

The aim is to study the relationship between blood eosinophils and neutrophils and FEV₁ decline in a long-term follow-up of a population-based adult asthma cohort.

Methods

In 2012–2014, an adult asthma cohort was invited to a follow-up including spirometry, blood sampling, and structured interviews, and n = 892 participated (55% women, mean age 59 y, 32–92 y). Blood eosinophils, neutrophils and FEV ₁ decline were analyzed both as continuous variables and divided into categories with different cut-offs. Regression models adjusted for smoking, exposure to vapors, gas, dust, or fumes (VGDF), use of inhaled and oral corticosteroids, and other possible confounders were utilized to analyze the relationship between eosinophils and neutrophils at follow-up and FEV₁ decline.

Results

The mean follow-up time was 18 years, and the mean FEV ₁ decline was 27 ml/year. The annual FEV₁ decline was related to higher levels of both blood eosinophils and neutrophils at follow-up, but only the association with eosinophils remained when adjusted for confounders. Further, the association between FEV₁ decline and eosinophils was stronger among those using ICS. With EOS <0.3 × 10⁹/L as reference, a more rapid decline in FEV1 was independently related to EOS ≥0.4 × 10⁹/L in adjusted analyses.

Conclusions and clinical relevance

Besides emphasizing the importance of smoking cessation and reduction of other harmful exposures, our real-world results indicate that there is an independent relationship between blood eosinophils and FEV₁ decline among adults with asthma.

Toward the Existence of a Sympathetic Neuroplasticity Adaptive Mechanism Influencing the Immune Response. A Hypothetical View-Part II

In the preceding work, a hypothesis on the existence of a specific neural plasticity program from sympathetic fibers innervating secondary lymphoid organs was introduced. This proposed adaptive mechanism would involve segmental retraction and degeneration of noradrenergic terminals during the immune system (IS) activation followed by regeneration once the IS returns to the steady-state. Starting from such view, this second part presents clinical and experimental evidence allowing to envision that this sympathetic neural plasticity mechanism is also operative on inflamed non-lymphoid peripheral tissues. Importantly, the sympathetic nervous system regulates most of the physiological bodily functions, ranging from cardiovascular, respiratory and gastro-intestinal functions to endocrine and metabolic ones, among others. Thus, it seems sensible to think that compensatory programs should be put into place during inflammation in non-lymphoid tissues as well, to avoid the possible detrimental consequences of a sympathetic blockade. Nevertheless, in many pathological scenarios like severe sepsis, chronic inflammatory diseases, or maladaptive immune responses, such compensatory programs against noradrenergic transmission impairment would fail to develop. This would lead to a manifest sympathetic dysfunction in the above-mentioned settings, partly accounting for their underlying pathophysiological basis; which is also discussed. The physiological/teleological significance for the whole neural plasticity process is postulated, as well.

Hyperpolarized Helium 3 MRI in Mild-to-Moderate Asthma: Prediction of Postbronchodilator Reversibility

Background Longitudinal progression to irreversible airflow limitation occurs in approximately 10% of patients with asthma, but it is difficult to identify patients who are at risk for this transition. Purpose To investigate 6-year longitudinal changes in hyperpolarized helium 3 (³He) MRI ventilation defects in study participants with mild-to-moderate asthma and identify predictors of longitudinal changes in postbronchodilator forced expiratory volume in 1 second (FEV₁) reversibility Materials and Methods Spirometry and hyperpolarized ³He MRI were evaluated in participants with mild-to-moderate asthma in two prospectively planned visits approximately 6 years apart. Participants underwent methacholine challenge at baseline (January 2010 to April 2011) and pre- and postbronchodilator evaluations at follow-up (November 2016 to June 2017). FEV₁ and MRI ventilation defects, quantified as ventilation defect volume (VDV), were compared between visits by using paired t tests. Participants were dichotomized by postbronchodilator change in FEV₁ at follow-up, and differences between reversible and not-reversible groups were determined by using unpaired t tests. Multivariable models were generated to explain postbronchodilator FEV₁ reversibility at follow-up. Results Eleven participants with asthma (mean age, 42 years ± 9 [standard deviation]; seven men) were evaluated at baseline and after mean 78 months ± 7. Medications, exacerbations, FEV₁ (76% predicted vs 76% predicted; P = .91), and VDV (240 mL vs 250 mL; P = .92) were not different between visits. In eight of 11 participants (73%), MRI ventilation defects at baseline were at the same location in the lung at follow-up MRI. In the remaining three participants (27%), MRI ventilation defects worsened at the same lung locations as depicted at baseline methacholine-induced ventilation. At follow-up, postbronchodilator FEV₁ was not reversible in six of 11 participants; the concentration of methacholine to decrease FEV₁ by 20% (PC₂₀) was greater in FEV₁-irreversible participants at follow-up (P = .01). In a multivariable model, baseline MRI VDV helped to predict postbronchodilator reversibility at follow-up (R ² = 0.80; P < .01), but PC₂₀, age, and FEV₁ did not (R ² = 0.63; P = .15). Conclusion MRI-derived, spatially persistent ventilation defects predict postbronchodilator reversibility 78 months ± 7 later for participants with mild-to-moderate asthma in whom there were no changes in lung function, medication, or exacerbations. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Stojanovska in this issue.

Over- and under-diagnosis in asthma

Asthma is extremely common with a prevalence of approximately 10% in Europe. It presents with symptoms which have a broad differential diagnosis and examination can be entirely normal. There is no agreed gold standard to diagnose asthma, and the objective tests that can aid diagnosis are often poorly available to primary care physicians. There is evidence that asthma is widely misdiagnosed. Overdiagnosis leads to unnecessary treatment and a delay in making an alternative diagnosis. Underdiagnosis risks daily symptoms, (potentially serious) exacerbations and long-term airway remodelling. An agreed standardised approach to diagnosis, with inclusion of objective measurements prior to treatment, is required to reduce misdiagnosis of asthma.

Asthma is frequently misdiagnosed. Both over- and under-diagnosis are associated with inappropriate treatment and potential patient harm. Although no gold standard diagnostic test is available, objective testing can improve diagnostic accuracy.http://ow.ly/Ej3830ohfxJ

Pathophysiology of severe asthma: We've only just started

Severe asthma is defined by the high treatment requirements to partly or fully control the clinical manifestations of disease. It remains a problem worldwide with a large burden for individuals and health services. The key to improving targeted treatments, reducing disease burden and improving patient outcomes is a better understanding of the pathophysiology and mechanisms of severe disease. The heterogeneity, complexity and difficulties in undertaking clinical studies in severe asthma remain challenges to achieving better understanding and better outcomes. In this review, we focus on the structural, mechanical and inflammatory abnormalities that are relevant in severe asthma.

Joint statement for the diagnosis, management, and prevention of chronic obstructive pulmonary disease for Gulf Cooperation Council countries and Middle East-North Africa region, 2017

Smoking and subsequent development of COPD is an ever-increasing epidemic in Arabian Gulf and Middle East countries, with no signs of decline. The important fact to be highlighted is that this COPD epidemic of increasing incidence and prevalence is mostly unrecognized by patients, due to the common attribution of symptoms to "smoker's cough", and the underdiagnosis and undertreatment by physicians because the common signs and symptoms masquerade as asthma. Consequently, there are long-term adverse effects of missing the diagnosis. The purpose of this review article is to focus upon the status of COPD in Arabian Gulf and Middle East countries, stressing the increasing burden of smoking and COPD, to emphasize the specific factors leading to rise in prevalence of COPD, to bring to light the underdiagnosis and undermanagement of COPD, and to treat COPD in conformity with standard guidelines with local and regional modifications. This review ends with suggestions and recommendations to the health department to formulate policies and to generate awareness among the general public about the side effects of smoking and consequences of COPD.

Characteristics of non-smoking adult asthma patients with chronic airflow limitation

OBJECTIVE

Chronic airflow limitation (CAL) can develop in a subgroup of patients with asthma. Characterising these patients is important because reduced lung function is a risk factor for adverse asthma outcomes. We hypothesised that heterogeneity in patients with CAL may be influenced by age at asthma onset. We first compared never-smoking asthma patients with and without CAL, and subsequently examined the differences between patients with late and early-onset asthma within the CAL cohort.

METHODS

Patients seen in our hospital's respiratory clinic between 1 Jan 2015 and 31 December 2015 were recruited to the study. CAL was defined as post-bronchodilator forced expiratory volume in 1 second (FEV1)<80% predicted, in the presence of post-bronchodilator ratio <70%. Variables independently associated with CAL were determined using a multivariate logistic regression model. Comparisons between patients with late-onset asthma (age ≥18 years) and early-onset asthma were made within the CAL cohort.

RESULTS

247 patients were included in the study. Age was the only variable independently associated with CAL after regression analysis, with an increase in odds of 3.8% (95% CI 0.4-7.3%) for every 1 year increase in age, p = 0.027. 63.2% of patients with CAL had late-onset asthma. Compared to patients with early-onset asthma, those with late-onset asthma had higher fractional exhaled nitric oxide levels (43 ± 32 ppb vs 20 ± 8 pb, p = 0.008).

CONCLUSIONS

An increase in age is associated with CAL in never-smoking asthma patients. In addition, age at asthma onset appears to influence airway inflammation in patients with CAL.

High resolution computed tomographic evaluation of bronchial wall thickness in healthy and clinically asthmatic cats

The objective of study is to determine the thickness of bronchial walls of clinically diagnosed asthmatic cats using high resolution computed tomography (HRCT) compared to that of healthy cats. The bronchial walls and pulmonary arteries were measured in healthy 16 cats and clinically asthmatic 4 cats. The bronchial walls and pulmonary arteries were measured under general anesthesia with positive pressure inspiration using HRCT. In healthy and asthmatic cats, bronchial lumen to the artery ratio (BA ratio), the ratio of bronchial wall thickness to bronchial diameter (TD ratio) and ratio of bronchial wall thickness to pulmonary artery (TA ratio) were measured. The mean BA ratio, TD ratio and TA ratio in healthy cats were 0.86 ± 0.12, 0.18 ± 0.02 and 0.25 ± 0.05, respectively. Under the same condition, the mean BA ratio, TD ratio and TA ratio in asthmatic cats were 0.93 ± 0.21, 0.22 ± 0.24 and 0.37 ± 0.06. The TD ratio and TA ratio in asthmatic cats were significantly higher than healthy cats (P<0.001). BA ratio was not significantly different in both groups (P>0.05). The evaluation of bronchial wall thickness by HRCT could be useful for diagnosis of disease of bronchial wall thickening, such as feline asthma.

Epithelial-mesenchymal transition promotes reactivity of human lung adenocarcinoma A549 cells to CpG ODN

BACKGROUND

Epithelial-mesenchymal transition (EMT) is reported to promote airway remodeling in asthmatics, which is the main histological change that causes complex and severe symptoms in asthmatics. However, little is known about whether EMT also plays a role in acute exacerbations of asthma evoked by respiratory tract infections.

METHODS

A human lung adenocarcinoma line, A549, was incubated with TGF-β1 at 10 ng/ml to induce EMT. Then the cells were stimulated with CpG ODN. Expression of surface and intracellular molecules was analyzed by flow cytometry. IL-6, IL-8 and MCP-1 in the culture supernatant were measured by Cytometric Bead Assay, and the expression of mRNA was quantitated by real-time PCR. CpG ODN uptake was analyzed by flow cytometry.

RESULTS

The culture supernatant levels of IL-6, IL-8 and MCP-1 and the expression of mRNA for these cytokines in CpG ODN-stimulated A549 cells that had undergone EMT was significantly higher compared to those that had not. Addition of ODN H154, a TLR9-inhibiting DNA, significantly suppressed the CpG ODN-induced production of those cytokines. However, flow cytometry found the level of TLR9 expression to be slightly lower in A549 cells that had undergone EMT compared to those that had not. On the other hand, CpG ODN uptake was increased in cells that had undergone EMT.

CONCLUSIONS

EMT induction of A549 cells enhanced CpG ODN uptake and CpG ODN-induced production of IL-6, IL-8 and MCP-1. These results suggest that EMT plays an important role in exacerbation in asthmatics with airway remodeling by enhancing sensitivity to extrinsic pathogens.

Measurement of exhaled nitric oxide concentration in asthma: a systematic review and economic evaluation of NIOX MINO, NIOX VERO and NObreath

BACKGROUND

High fractions of exhaled nitric oxide (FeNO) in the breath of patients with symptoms of asthma are correlated with high levels of eosinophils and indicate that a patient is likely to respond to inhaled corticosteroids. This may have a role in the diagnosis and management of asthma.

OBJECTIVE

To assess the diagnostic accuracy, clinical effectiveness and cost-effectiveness of the hand-held electrochemical devices NIOX MINO(®) (Aerocrine, Solna, Sweden), NIOX VERO(®) (Aerocrine) and NObreath(®) (Bedfont Scientific, Maidstone, UK) for the diagnosis and management of asthma.

DATA SOURCES

Systematic searches were carried out between March 2013 and April 2013 from database inception. Databases searched included MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects, Science Citation Index Expanded and Conference Proceedings Citation Index - Science. Trial registers such as ClinicalTrials.gov and the metaRegister of Controlled Trials were also searched in March 2013. All searches were updated in September 2013.

REVIEW METHODS

A rapid review was conducted to assess the equivalence of hand-held and chemiluminescent FeNO monitors. Systematic reviews of diagnostic accuracy and management efficacy were conducted. A systematic review of economic analyses was also conducted and two de novo health economic models were developed. All three reviews were undertaken according to robust high-quality methodology.

RESULTS

The rapid review (27 studies) found varying levels of agreement between monitors (Bland-Altman 95% limits of agreement up to ±10 parts per billion), with better agreement at lower FeNO values. Correlation was good (generally r > 0.9). The diagnostic accuracy review identified 22 studies in adults (all ages) and four in children. No studies used NObreath or NIOX VERO and seven used NIOX MINO. Estimates of diagnostic accuracy varied widely. FeNO used in combination with another test altered diagnostic accuracy only slightly. High levels of heterogeneity precluded meta-analysis. Limited observations included that FeNO may be more reliable and useful as a rule-in than as a rule-out test; lower cut-off values in children and in smokers may be appropriate; and FeNO may be less reliable in the elderly. The management review identified five randomised controlled trials in adults, one in pregnant asthmatics and seven in children. Despite clinical heterogeneity, exacerbation rates were lower in all studies but not generally statistically significantly so. Effects on inhaled corticosteroid (ICS) use were inconsistent, possibly because of differences in management protocols, differential effectiveness in adults and children and differences in population severity. One UK diagnostic model and one management model were identified. Aerocrine also submitted diagnostic and management models. All had significant limitations including short time horizons and the selective use of efficacy evidence. The de novo diagnostic model suggested that the expected difference in quality-adjusted life-year (QALY) gains between diagnostic options is likely to be very small. Airway hyper-responsiveness by methacholine challenge test is expected to produce the greatest QALY gain but with an expected incremental cost-effectiveness ratio (ICER) compared with FeNO (NObreath) in combination with bronchodilator reversibility of £1.125M per QALY gained. All remaining options are expected to be dominated. The de novo management model indicates that the ICER of guidelines plus FeNO monitoring using NObreath compared with guidelines alone in children is expected to be approximately £45,200 per QALY gained. Within the adult subgroup, FeNO monitoring using NObreath compared with guidelines alone is expected to have an ICER of approximately £2100 per QALY gained. The results are particularly sensitive to assumptions regarding changes in ICS use over time, the number of nurse visits for FeNO monitoring and duration of effect.

CONCLUSIONS

Limitations of the evidence base impose considerable uncertainty on all analyses. Equivalence of devices was assumed but not assured. Evidence for diagnosis is difficult to interpret in the context of inserting FeNO monitoring into a diagnostic pathway. Evidence for management is also inconclusive, but largely consistent with FeNO monitoring resulting in fewer exacerbations, with a small or zero reduction in ICS use in adults and a possible increased ICS use in children or patients with more severe asthma. It is unclear which specific management protocol is likely to be most effective. The economic analysis indicates that FeNO monitoring could have value in diagnostic and management settings. The diagnostic model indicates that FeNO monitoring plus bronchodilator reversibility dominates many other diagnostic tests. FeNO-guided management has the potential to be cost-effective, although this is largely dependent on the duration of effect. The conclusions drawn from both models require strong technical value judgements with respect to several aspects of the decision problem in which little or no empirical evidence exists. There are many potential directions for further work, including investigations into which management protocol is best and long-term follow-up in both diagnosis and management studies.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013004149.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Once-daily fluticasone furoate/vilanterol versus twice daily combination therapies in asthma-mixed treatment comparisons of clinical efficacy

Background

Fluticasone furoate (FF)/vilanterol (VI) is a once-daily inhaled corticosteroid (ICS)/long-acting beta₂ agonist (LABA) combination. FF/VI, 92/22mcg and 184/22mcg, are approved in Europe as maintenance therapy in persistent asthma. We report data from mixed treatment comparisons (MTC) of once-daily FF/VI against established twice-daily ICS/LABA combination therapies on clinical efficacy outcomes.

Methods

Data from 31 parallel-group randomised controlled trials (RCTs) of ICS/LABA, of ≥8 weeks’ duration in patients aged ≥12 years with asthma, identified by systematic review, were analysed using covariate-adjusted Bayesian hierarchical models for four efficacy outcomes (primary analysis). Lung function, assessed by change from baseline morning peak expiratory flow (PEF) (n = 18 studies) and forced expiratory volume in 1 s (FEV₁) (n = 28), was the outcome of primary interest. Secondary objectives were assessment of relative efficacy in terms of exacerbation rates (n = 6) and health status (n = 7). Overall, 24 different treatment arms were included in the MTC; we report findings comparing FF/VI (92/22mcg and 184/22mcg) with fluticasone propionate/salmeterol (FP/SAL) (250/50mcg and 500/50mcg) and budesonide/formoterol (BUD/FORM) (320/9mcg and 640/18mcg).

Results

For PEF (margin = 12 l/min), FF/VI 92/22mcg demonstrated ≥94 % probability and FF/VI 184/22mcg >99 % probability of non-inferiority to corresponding doses of both FP/SAL and BUD/FORM. For FEV₁ (margin = 100 ml), FF/VI demonstrated ≥98 % (92/22mcg) and >99 % (184/22mcg) probability of non-inferiority to both FP/SAL and BUD/FORM. Findings for exacerbations were inconclusive due to lack of data: FF/VI 92/22mcg demonstrated 74 % and 82 % probability of non-inferiority (margin = 10 %) to FP/SAL 250/50mcg and BUD/FORM 320/9mcg, respectively. For Asthma Quality of Life Questionnaire (AQLQ) score, FF/VI 92/22mcg demonstrated >99 % and 90 % probability of non-inferiority (margin = 0.25) to FP/SAL 250/50mcg and BUD/FORM 320/9mcg. Data were unavailable to assess non-inferiority of FF/VI 184/22mcg on exacerbations or AQLQ.

Conclusions

Both strengths of once-daily FF/VI in asthma were comparable with corresponding doses of twice-daily FP/SAL and BUD/FORM in terms of lung function in this MTC analysis. FF/VI 92/22mcg was comparable with FP/SAL and BUD/FORM on AQLQ, but exacerbation results were inconclusive. Model limitations include disconnected treatment networks and variability across studies. Our data support previous RCT findings suggesting that the efficacy of once-daily FF/VI in improving lung function and health status in asthma is comparable with twice-daily ICS/LABAs.

Electronic supplementary material

The online version of this article (doi:10.1186/s40733-015-0016-0) contains supplementary material, which is available to authorized users.

Revisiting the Dutch hypothesis

The Dutch hypothesis was first articulated in 1961, when many novel and advanced scientific techniques were not available, such as genomics techniques for pinpointing genes, gene expression, lipid and protein profiles, and the microbiome. In addition, computed tomographic scans and advanced analysis techniques to dissect (small) airways disease and emphysema were not available. At that time, the group of researchers under the visionary guidance of Professor N. G. M. Orie put forward that both genetic and environmental factors can determine whether one would have airway obstructive diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Moreover, they stipulated that the phenotype of obstructive airway disease could be affected by sex and changes with aging. Orie and colleagues' call to carefully phenotype patients with obstructive airways diseases has been adopted by many current researchers in an attempt to determine the heterogeneity of both asthma and COPD to better define these diseases and optimize their treatment. The founders of the Dutch hypothesis were far ahead of their time, and we can learn from their insights. We should fully characterize all patients in our clinical practice and not just state that they have asthma, COPD, or asthma and COPD overlap syndrome. This detailed phenotyping can help in understanding these obstructive airway diseases and provide guidance for disease management.

The asthma COPD overlap syndrome (ACOS)

Asthma and chronic obstructive pulmonary disease (COPD) have traditionally been viewed as distinct clinical entities. Recently, however, much attention has been focused on patients with overlapping features of both asthma and COPD: those with asthma COPD overlap syndrome (ACOS). Although no universal definition criteria exist, recent publications attempted to define patients with ACOS based on differences in clinical features, radiographic findings, and diagnostic tests. Patients with ACOS make up a large percentage of those with obstructive lung disease and have a higher overall health-care burden. Identifying patients with ACOS has significant therapeutic implications particularly with the need for early use of inhaled corticosteroids and the avoidance of use of long-acting bronchodilators alone in such patients. However, unlike asthma and COPD, no evidence-based guidelines for the management of ACOS currently exist. Future research is needed to improve our understanding of ACOS and to achieve the best management strategies.

Childhood-onset asthma in smokers. association between CT measures of airway size, lung function, and chronic airflow obstruction

RATIONALE AND OBJECTIVES

Asthma is associated with chronic airflow obstruction. Our goal was to assess the association of computed tomographic measures of airway wall volume and lumen volume with the FEV1 and chronic airflow obstruction in smokers with childhood-onset asthma.

METHODS

We analyzed clinical, lung function, and volumetric computed tomographic airway volume data from 7,266 smokers, including 590 with childhood-onset asthma. Small wall volume and small lumen volume of segmental airways were defined as measures 1 SD below the mean. We assessed the association between small wall volume, small lumen volume, FEV1, and chronic airflow obstruction (post-bronchodilator FEV1/FVC ratio < 0.7) using linear and logistic models.

MEASUREMENTS AND MAIN RESULTS

Compared with subjects without childhood-onset asthma, those with childhood-onset asthma had smaller wall volume and lumen volume (P < 0.0001) of segmental airways. Among subjects with childhood-onset asthma, those with the smallest wall volume and lumen volume had the lowest FEV1 and greatest odds of chronic airflow obstruction. A similar tendency was seen in those without childhood-onset asthma. When comparing these two groups, both small wall volume and small lumen volume were more strongly associated with FEV1 and chronic airflow obstruction among subjects with childhood-asthma in multivariate models.

CONCLUSION

In smokers with childhood-onset asthma, smaller airways are associated with reduced lung function and chronic airflow obstruction. Clinical trial registered with www.clinicaltrials.gov (NCT00608764).

Asthma, COPD and overlap syndrome: a longitudinal study in young European adults

We compared risk factors and clinical characteristics, 9-year lung function change and hospitalisation risk across subjects with the asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS), asthma or COPD alone, or none of these diseases.Participants in the European Community Respiratory Health Survey in 1991-1993 (aged 20-44 years) and 1999-2001 were included. Chronic airflow obstruction was defined as pre-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity<lower limit of normal on both occasions. Based on their history of respiratory symptoms, spirometry and risk factors, subjects were classified as having asthma alone (n=941), COPD alone (n=166), ACOS (n=218) and none of these (n=5659).Subjects with ACOS shared risk factors and clinical characteristics with subjects with asthma alone, but they had an earlier age of asthma onset. FEV1 change in the ACOS group (-25.9 mL·year(-1)) was similar to that in the asthma group (-25.3 mL·year(-1)), and lower (p<0.001) than in the COPD group (-37.3 mL·year(-1)). ACOS was associated with the highest hospitalisation rate.Among young adults aged 20-44 years, ACOS seems to represent a form of severe asthma, characterised by more frequent hospitalisations, and to be the result of early-onset asthma that has progressed to fixed airflow obstruction.

Asthma-COPD overlap 2015: now we are six

BACKGROUND

The overlap between asthma and COPD is increasingly recognised. This review examines the new insights, treatment and remaining knowledge gaps for asthma-COPD overlap.

METHOD

A systematic literature review of cluster analyses of asthma and COPD was performed. Articles from 2009 to the present dealing with prevalence, morbidity and treatment of asthma-COPD overlap were identified and reviewed.

RESULTS

Asthma-COPD overlap was consistently recognised in studies using a variety of different study designs and sampling. The prevalence was approximately 20% in patients with obstructive airways diseases. Asthma-COPD overlap was associated with increased morbidity and possibly an increased mortality and comorbidity. There was evidence of a heterogeneous pattern of airway inflammation that included eosinophilic (in adult asthma), neutrophilic or mixed patterns (in severe asthma and COPD). Systemic inflammation was present in asthma-COPD overlap and resembled that of COPD. Within asthma-COPD overlap, there is evidence of different subgroups, and recognition using bronchodilator responsiveness has not been successful. Guidelines generally recommend a serial approach to assessment, with treatment recommendations dominated by an asthma paradigm. Research is needed into key clinical features that impact outcome, mechanisms and treatment approaches in asthma-COPD overlap. Identifying and treating disease components by multidimensional assessment shows promise.

CONCLUSIONS

Asthma-COPD overlap has drawn attention to the significant heterogeneity that exists within obstructive airway diseases. It should be replaced by novel approaches that identify and manage the components of this heterogeneity, such as multidimensional assessment and treatment. Future research is needed to test these novel and personalised approaches.

Angiotensin-(1-7) attenuates airway remodelling and hyperresponsiveness in a model of chronic allergic lung inflammation

BACKGROUND AND PURPOSE

A long-term imbalance between pro- and anti-inflammatory mediators leads to airway remodelling, which is strongly correlated to most of the symptoms, severity and progression of chronic lung inflammation. The Angiotensin-(1-7) [Ang-(1-7)]/Mas receptor axis of the renin-angiotensin system is associated with attenuation of acute and chronic inflammatory processes. In this study, we investigated the effects of Ang-(1-7) treatment in a model of chronic allergic lung inflammation.

EXPERIMENTAL APPROACH

Mice were sensitized to ovalbumin (OVA; 4 injections over 42 days, 14 days apart) and were challenged three times per week (days 21-46). These mice received Ang-(1-7) (1 μg·h(-1) , s.c.) by osmotic mini-pumps, for the last 28 days. Histology and morphometric analysis were performed in left lung and right ventricle. Airway responsiveness to methacholine, analysis of Ang-(1-7) levels (RIA), collagen I and III (qRT-PCR), ERK1/2 and JNK (Western blotting), IgE (elisa), cytokines and chemokines (elisa multiplex), and immunohistochemistry for Mas receptors were performed.

KEY RESULTS

Infusion of Ang-(1-7) in OVA-sensitized and challenged mice decreased inflammatory cell infiltration and collagen deposition in the airways and lung parenchyma, and prevented bronchial hyperresponsiveness. These effects were accompanied by decreased IgE and ERK1/2 phosphorylation, and decreased pro-inflammatory cytokines. Mas receptors were detected in the epithelium and bronchial smooth muscle, suggesting a site in the lung for the beneficial actions of Ang-(1-7).

CONCLUSIONS AND IMPLICATIONS

Ang-(1-7) exerted beneficial attenuation of three major features of chronic asthma: lung inflammation, airway remodelling and hyperresponsiveness. Our results support an important protective role of Ang-(1-7) in lung inflammation.

Fixed airways obstruction among patients with severe asthma: findings from the Singapore General Hospital-Severe Asthma Phenotype Study

Background

A subset of severe asthma patients has fixed airways obstruction, which is characterized by incomplete reversibility to bronchodilator challenge. We aimed to elucidate the factors associated with fixed airways obstruction in a cohort of patients with severe asthma in Singapore.

Methods

245 patients from the Singapore General Hospital-Severe Asthma Phenotype Study (SGH-SAPS) were screened. These patients fulfilled World Health Organization criteria for "treatment-resistant severe asthma" and were all on combination of high-dose inhaled corticosteroids and long-acting beta2 agonists. 76 patients had pre- and postbronchodilator lung function tests and were selected for analysis. They were divided into two groups based on postbronchodilator (Post BD) forced expiratory volume in one second, PostBDFEV₁ % predicted: ≥70% (Non-Fixed Obs) and < 70% (Fixed Obs). We compared clinical and demographic parameters between the two groups.

Results

Patients in the Fixed Obs group were more frequently past or current smokers and had a higher pack-year smoking history. Overall, pack-year smoking history had a modest negative correlation with PostBDFEV₁ % predicted. Atopy, allergen sensitization (type and numbers), comorbidities, symptoms, health care utilization and medication use did not differ between the two groups. The prebronchodilator FEV₁ % predicted, FEV₁/FVC and FVC % predicted were significantly lower in the Fixed Obs group. In addition, prebronchodilator FVC % predicted accounted for more variability than FEV₁/FVC in predicting PostBDFEV₁% predicted.

Conclusion

Smoking is associated with fixed airways obstruction in patients with treatment-resistant severe asthma in Singapore. Furthermore, our results suggest that both small and large airways obstruction contribute independently to fixed airways obstruction in severe asthma.

The association of asthma and atrial fibrillation--a nationwide population-based nested case-control study

BACKGROUND

Asthma and atrial fibrillation (AF) have been reported to be related to an increased risk of cardiovascular events. However, the relationship between asthma and AF has not been fully elucidated. The purpose of this study was to examine the association between asthma and AF risk.

METHODS

We conducted a population-based nested case-control study including a total of 7439 newly-diagnosed adult patients with AF and 10,075 age-, gender-, comorbidity-, and cohort entry date-matched subjects without AF from the Taiwan National Health Insurance database. Exposure to asthma as well as medications including bronchodilators and corticosteroid before the index date was evaluated to investigate the association between AF and asthma as well as concurrent medications.

RESULTS

AF patients were 1.2 times (adjusted OR 1.2, 95% CI 1.109-1.298) more likely to be associated with a future occurrence of asthma independent of comorbidities and treatment with corticosteroids and bronchodilator. In addition, the risks of new-onset AF were significantly higher among current users of inhaled corticosteroid, oral corticosteroids, and bronchodilators. Newly users (within 6 months) have the highest risk (inhaled corticosteroid: OR, 2.13; 95% CI, 1.226-3.701, P=0.007; oral corticosteroid: OR, 1.932; 95% CI, 1.66-2.25, P<0.001; non-steroid bronchodilator: OR, 2.849; 95% CI, 2.48-3.273, P<0.001). A graded association with AF risk was also observed among subjects treated with corticosteroid (inhaled and systemic administration) and bronchodilators. New users (within 6 months) of these medications had the highest risk of AF (ICS: OR, 2.13; 95% CI, 1.226-3.701, P=0.007; oral corticosteroid: OR, 1.932; 95% CI, 1.66-2.25, P<0.001; non-steroid bronchodilator: OR, 2.849; 95% CI, 2.48-3.273, P<0.001). A graded association with AF risk was also observed among subjects treated with ICS or bronchodilator.

CONCLUSIONS

Asthma was associated with an increased risk of developing future AF.

The independent and combined effects of lifetime smoke exposures and asthma as they relate to COPD

Chronic obstructive pulmonary disease (COPD) is part of a worldwide tobacco-related disease epidemic, and is associated with progressive airflow obstruction and varying degrees of emphysema and/or hyperinflation. Greater focus has been placed recently on the potential for early life factors to influence the development of COPD, based on the premise that delayed lung growth during childhood and adolescence might predispose to lung disease in later life. For most people, the adverse effects on lung function of adult and early childhood factors are additive, which provides no additional incentive for current smokers to quit. However, if there is a (synergistic) interaction between active smoking and asthma, smoking cessation is likely to have a greater lung function benefit for the smoker who is also asthmatic, especially if quitting occurs at an early age. This article critically evaluates the evidence for the independent associations of lifetime asthma, smoking and smoke exposures with airflow obstruction, plus their interaction when multiple factors are present.

Potential role of pentosidine on susceptibility to small airway closure in elderly and smoking asthma

BACKGROUND

Small airway closure in asthma is determined by a complex interaction of structural and functional characteristics including lung elastic recoil. Recently, we determined that loss of elastic recoil might be attributable to pentosidine level in the airways. This study was designed to investigate the influences of aging and smoking on small airway closure in asthma.

METHODS

Sixty-one patients with asthma (20 non-smoking young adult, 23 non-smoking elderly, and 18 smoking young adult) and 36 control subjects (12 non-smoking young adult, 11 non-smoking elderly, and 13 smoking young adult) were included. We assessed airway responses during methacholine provocation and calculated the closing index. In addition, we measured pentosidine levels in induced sputum from all study subjects.

RESULTS

Pentosidine levels in induced sputum were markedly higher in asthmatic patients than in controls. In control subjects, the intergroup differences in pentosidine level among 3 subgroups were significant. Similarly, pentosidine levels were significantly higher in non-smoking elderly and smoking young adult asthmatics than in non-smoking young adult asthmatics. There was no significant difference in pentosidine levels between non-smoking elderly and smoking young adult asthmatics. The closing index was also significantly higher in non-smoking elderly and smoking young adult asthmatics than in non-smoking young adult asthmatics. Moreover, pentosidine levels in non-smoking elderly and smoking young adult asthmatics were closely correlated with closing index.

CONCLUSIONS

We determined the correlation of pentosidine level with susceptibility to small airway closure in elderly and smoking asthmatics. Our results might facilitate the understanding of elderly and smoking asthma.

Asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS): current literature review

Asthma and chronic obstructive pulmonary disease (COPD) are chronic diseases, very common in general population. These obstructive airway illnesses are manifested with chronic inflammation affecting the whole respiratory tract. Obstruction is usually intermittent and reversible in asthma, but is progressive and irreversible in COPD. Asthma and COPD may overlap and converge, especially in older people [overlap syndrome-asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS)]. Although ACOS accounts approximately 15-25% of the obstructive airway diseases, is not well recognised because of the structure of clinical trials. COPD studies exclude asthma patients and asthma studies exclude COPD patients, respectively. It is crucial to define asthma, COPD and overlap syndrome (ACOS), as notable clinical entities, which they share common pathologic and functional features, but they are characterized from differences in lung function, acute exacerbations, quality of life, hospital impact and mortality.

A Quantitative Study of Airway Changes on Micro-CT in a Mouse Asthma Model: Comparison With Histopathological Findings

Purpose

To evaluate airway changes in ovalbumin-induced asthmatic mice in terms of postmortem micro-CT images and pathological findings.

Methods

Asthma was induced in mice by intraperitoneal injection and nasal instillation of ovalbumin aluminium hydroxide into mice (experimental group, n=6), and another group of mice received intraperitoneal injection and nasal instillation of distilled phosphate-buffered saline (control group, n=6). Bronchial lumen area was measured in the main bronchial lumen of the distal third bronchial branch level (6 parts per each mouse) on axial scans of Micro-CT, using a Lucion's smart pen (semi-automated) and a curve pen (manual). Bronchial wall thickness was obtained in 4 sections (2 levels on either side) after the third bronchial branch by measuring the diameter which was perpendicular to the longitudinal axis of the main bronchus on curved Multi-planar reconstruction (MPR) images. Histologic slides were obtained from the lesion that was matched with its CT images, and bronchial wall thicknesses were determined.

Results

The mean bronchial lumen area was 0.196±0.072 mm² in the experimental group and 0.243±0.116 mm² in the control group; the difference was significant. Bronchial wall thickness on micro-CT images (mean, 0.119±0.01 vs. 0.108±0.013 mm) and in pathological specimens (mean, 0.066±0.011 vs. 0.041±0.009 mm) were thicker in the experimental group than in the control group; bronchial wall thickness on micro-CT images correlated well with pathological thickness (for the experimental group, r=0.712; for the control group, r=0.46). The thick bronchial wall in the experimental group demonstrated submucosal hypertrophy along with goblet cell hyperplasia and smooth muscle hyperplasia.

Conclusions

The results of this study suggest that asthma may induce thickening of bronchial wall and narrowing of the lumen area on micro-CT images and that these results may significantly correlate with pathological findings.

Chronic obstructive pulmonary disease in non-smokers: a case-comparison study

BACKGROUND

COPD is often regarded as a smoker's disease. In fact, up to 50% of COPD could be attributable to other causes. Relatively little is known about COPD among nonsmokers, and this group is usually excluded from studies of COPD.

METHODS

In this cross-sectional case-comparison study, smokers and nonsmokers aged over 45 with COPD (post-bronchodilator FEV1 ≤ 70% predicted, FEV1/FVC ratio < 0.7) were recruited from specialist outpatient clinics and from primary care. Subjects completed a questionnaire and interview, and underwent spirometry, venesection, exhaled nitric oxide (ENO) measurement, allergen skinprick testing, formal lung function testing and high resolution CT.

RESULTS

48 nonsmokers and 45 smokers participated. Asthma was nearly universal among nonsmokers and was the commonest identifiable cause of COPD in that group. Nonsmokers also exhibited a high prevalence of objective eosinophilic inflammation (raised ENO and eosinophil counts, positive skinprick tests). Smokers had more severe airflow obstruction, but respiratory symptom prevalences were similar between groups. Nonsmokers reported greater lifetime burdens of respiratory disease. Nonsmokers' HRCT results showed functional small airways disease, with no significant emphysema in any subject. Previously undiagnosed bronchiectasis was common in both groups (31% and 42%).

CONCLUSIONS

Asthma is a very common cause of COPD among nonsmokers. Radiological bronchiectasis is common in COPD; the clinical significance of this finding is unclear.

Hyperpolarized (3) He and (129) Xe MRI: differences in asthma before bronchodilation

PURPOSE

To compare hyperpolarized helium-3 ((3) He) and xenon-129 ((129) Xe) MRI in asthmatics before and after salbutamol inhalation.

MATERIALS AND METHODS

Seven asthmatics provided written informed consent and underwent spirometry, plethysmography, and MRI before and after salbutamol inhalation. (3) He and (129) Xe ventilation defect percent (VDP) and ventilation coefficient of variation (COV) were measured. To characterize the airways spatially related to ventilation defects, wall area percent (WA%) and lumen area (LA) were evaluated for two subjects who had thoracic x-ray computed tomography (CT) acquired 1 year before MRI.

RESULTS

Before salbutamol inhalation, (129) Xe VDP (8 ± 5%) was significantly greater than (3) He VDP (6 ± 5%, P = 0.003). Post-salbutamol, there was a significant improvement in both (129) Xe (5 ± 4%, P < 0.0001) and (3) He (4 ± 3%, P = 0.001) VDP, and the improvement in (129) Xe VDP was significantly greater (P = 0.008). (129) Xe MRI COV (Pre: 0.309 ± 0.028, Post: 0.296 ± 0.036) was significantly greater than (3) He MRI COV (Pre: 0.282 ± 0.018, Post: 0.269 ± 0.024), pre- (P < 0.0001) and post-salbutamol (P < 0.0001) and the decrease in COV post-salbutamol was significant ((129) Xe, P = 0.002; (3) He, P < 0.0001). For a single asthmatic, a sub-segmental (129) Xe MRI ventilation defect that was visible only before salbutamol inhalation but not visible using (3) He MRI was spatially related to a remodeled fourth generation sub-segmental airway (WA% = 78%, LA = 2.9 mm(2) ).

CONCLUSION

In asthma, hyperpolarized (129) Xe MRI may help reveal ventilation abnormalities before bronchodilation that are not observed using hyperpolarized (3) He MRI.

Persistent pulmonary function impairment in children and adolescents with asthma

OBJECTIVE

Asthma is the most common chronic pulmonary disease, characterized by bronchial inflammation. Some children with asthma have persistent pulmonary function impairment. The prevalence and etiology of this abnormality in children with asthma in developing countries remain unknown. The objective of this study was to estimate the proportion of patients with impaired pulmonary function who were unresponsive to treatment in a group of children and adolescents with asthma, and to describe the phenotypic characteristics of the sample.

METHODS

Using a standardized questionnaire, we selected outpatients (5-17 years of age) diagnosed with persistent asthma. These patients underwent spirometry and skin prick tests for sensitivity to common aeroallergens. Persistent pulmonary function impairment was defined as an FEV1/FVC ratio < 0.80, even after 10 days of treatment with bronchodilators and oral corticosteroids. We used the atopic index to differentiate between patients with little or no response to the skin prick test and those with a strong response (cut-off point: 4 allergens).

RESULTS

We included 96 patients with a mean age of 10.6 years. Of those, 52 (54.1%) were male, and 89 (92.7%) were atopic. Of the 96 patients, 8 (8.3%) had impaired pulmonary function even after the treatment. Among those patients, 8 (100%) were atopic, 7 (87.5%) had moderate or severe asthma, and 7 (87.5%) had a history of hospitalization for acute bronchiolitis.

CONCLUSIONS

Children and adolescents with moderate or severe asthma can present with impaired pulmonary function and be unresponsive to treatment. This clinical situation has been little studied in developing countries, and its risk factors and etiology will be better understood only through birth cohort studies.

Association of adult-onset asthma with specific cardiovascular conditions

BACKGROUND

While asthma is known to be associated with cardiovascular disease (CVD), the relation to specific manifestations of CVD has not been previously described. Our objective was to explore the relation of child and adult-onset asthma with specific CVD conditions.

METHODS

We examined data from 16,943 (projected 178 million) U.S. adults aged 18-90 years old with relevant information on asthma and CVD. The study was a cross-sectional analysis of the National Health and Nutrition Examination Survey 1999-2006. We determined the prevalence of CVD risk factors and likelihood of CVD conditions according to gender and asthma status using multiple logistic regression adjusted for age, gender and other CVD risk factors.

RESULTS

The proportions of subjects with child and adult-onset asthma were 4.8% (n=702) and 3.3% (n=534), respectively. Adult-onset asthma was significantly associated with total CVD (OR=2.07, CI=1.2-3.7), but child-onset asthma was not associated with any CVD conditions. Of the four specific CVD endpoints, adult-onset asthma overall was only associated with coronary heart disease (CHD) (OR=2.26, CI=1.2-4.2) in the total population.

CONCLUSIONS

Our data suggests that CHD is the major cardiovascular condition associated with asthma; a prospective study must be done to confirm a causal relationship.

Immunological basis of reversible and fixed airways disease

Asthma is characterized by airflow obstruction that is usually completely reversible either spontaneously or in response to treatment. However, a small subset of patients with asthma display FAO (fixed airflow obstruction) despite optimal treatment, a feature more commonly associated with smoking-induced COPD (chronic obstructive pulmonary disease). Why some asthma patients develop FAO is not understood, and it is not clear whether (i) they represent a subset of patients with more severe disease, (ii) they share some characteristics of patients who develop COPD, or (iii) they represent a different disease entity altogether. The present review compares the pulmonary inflammatory profile of asthma patients with FAO with those without FAO, as well as COPD sufferers. The inflammation in asthma patients with FAO can vary from neutrophilic with CD8 T-cell involvement, similar to that of COPD, to eosinophilic with CD4 Th2 cell involvement, akin to that of asthma patients without FAO. Although studies of FAO in asthma sufferers would benefit hugely from consistent inclusion criteria, further research work is also required to shed more light on the immunological processes involved.

The persistence of allergen exposure favors pulmonary function decline in workers with allergic occupational asthma

BACKGROUND

In asthmatics, a rapid decline in pulmonary function is observed, likely as a consequence of airways remodeling. Persistence of allergen exposure in patients with occupational asthma (OA) maintains chronic bronchial inflammation, resulting in a more severe lung function decline. Few studies were performed on the effects of allergen exposure cessation.

OBJECTIVE

This study aims at evaluating the influence of allergen exposure cessation on respiratory decline in allergic asthmatic workers.

METHODS

Two groups of workers with allergic OA were selected. The first group (30 workers) changed job after the diagnosis and was no more exposed to sensitizing allergens, and the second group (28 subjects) did not and, as a consequence of preventive measures in the work place, was exposed to a lower level of allergens. All were treated with conventional therapy, according to GINA protocols. FEV1 changes during a 12-year period were evaluated.

RESULTS

Despite pharmacological therapy, the pulmonary function decay slope was steeper in workers continuously exposed to the sensitizing agent (even at reduced level) than in those with a complete cessation of exposure: final FEV1 loss was 512.5 ± 180 ml versus 332.5 ± 108 ml, respectively. The difference became significant after 4 years from the cessation of the exposure.

CONCLUSIONS

The study shows that the cessation of the exposure to allergen in the work place appears the most effective measure in limiting pulmonary function decline in asthmatic workers and underlines the importance of allergic risk assessment and control in the management of occupational asthma.

Emerging pathways in asthma: innate and adaptive interactions

BACKGROUND

Allergic asthma is a complex and chronic airway inflammatory disorder, and the prevalence of asthma has increased. Adaptive antigen-dependent immunity is a classical pathway of asthmatic pathology. Recent studies have focused on innate antigen-independent immunity in asthma.

SCOPE OF REVIEW

This review discusses updated research associating innate immunity with allergic asthma. We focus on innate molecules (Toll-like receptors and nucleotide-binding oligomerization domain-like receptors) and review studies regarding innate and adaptive interactions in allergic responses (surfactant protein D, lipopolysaccharide, and early life immune responses). We also highlight new emerging concepts in the field applicable to innate immunity and asthma.

MAJOR CONCLUSIONS

Innate immunity plays a key role in asthma. Understanding innate and adaptive interactions provide significant information in asthmatic research. Innate molecules not only contribute to classical pulmonary defense, but also modulate inflammatory responses. Emerging concepts in the analysis of the microbiome, microRNA and autophagy may provide new insights in searching therapeutic targets.

GENERAL SIGNIFICANCE

Finding specific mechanisms of innate and/or adaptive immunity in asthma are timely goals for further research. Integration of bioinformatics and systems biology tools, particularly in relation to microbiome analysis, may be helpful in providing an understanding to allergic immune responses. This article is part of a Special Issue entitled Biochemistry of Asthma.

Potential roles of pentosidine in age-related and disease-related impairment of pulmonary functions in patients with asthma

BACKGROUND

Pentosidine is well established as an intermolecular cross-linking type of advanced glycation end products, and it accumulates with aging in various connective tissues.

OBJECTIVE

To determine whether pentosidine contributes to age-related and disease-related impairment of pulmonary functions in patients with asthma.

METHODS

We measured pentosidine levels in induced sputum from young to elderly patients with asthma and assessed the slope of the nitrogen (N(2)) alveolar plateau (delta N(2)), closing volume (CV), and closing capacity (CC) from a nitrogen washout curve in a single breath.

RESULTS

Pentosidine levels in induced sputum were significantly higher in patients with asthma than in normal controls (patients with asthma: median, 20.1, interquartile range, 16.7-26.5 ng/mL; normal controls: median, 3.0, interquartile range, 0.7-7.5 ng/mL; P < .001). The levels were closely correlated with age in both normal controls and patients with asthma. However, the slope of age-related increase in pentosidine levels was markedly steeper in patients with asthma than in normal controls. CV/vital capacity, CC/total lung capacity, and delta N(2) increased with aging in both normal controls and patients with asthma. Moreover, in each range of age (21-40, 41-60, 61-80 years), CV/vital capacity, CC/total lung capacity, and delta N(2) were significantly higher in patients with asthma than in normal controls. In addition, pentosidine levels in patients with asthma were closely correlated with each of these variables.

CONCLUSION

Our results demonstrated the association between sputum levels of pentosidine and age-related small airways function in both normal controls and patients with asthma. Moreover, the age-related increase in pentosidine levels was more pronounced in patients with asthma. These findings will herald new era in the pathophysiology of elderly asthma.

An official American Thoracic Society public policy statement: Novel risk factors and the global burden of chronic obstructive pulmonary disease

RATIONALE

Although cigarette smoking is the most important cause of chronic obstructive pulmonary disease (COPD), a substantial proportion of COPD cases cannot be explained by smoking alone.

OBJECTIVES

To evaluate the risk factors for COPD besides personal cigarette smoking.

METHODS

We constituted an ad hoc subcommittee of the American Thoracic Society Environmental and Occupational Health Assembly. An international group of members was invited, based on their scientific expertise in a specific risk factor for COPD. For each risk factor area, the committee reviewed the literature, summarized the evidence, and developed conclusions about the likelihood of it causing COPD. All conclusions were based on unanimous consensus.

MEASUREMENTS AND MAIN RESULTS

The population-attributable fraction for smoking as a cause of COPD ranged from 9.7 to 97.9%, but was less than 80% in most studies, indicating a substantial burden of disease attributable to nonsmoking risk factors. On the basis of our review, we concluded that specific genetic syndromes and occupational exposures were causally related to the development of COPD. Traffic and other outdoor pollution, secondhand smoke, biomass smoke, and dietary factors are associated with COPD, but sufficient criteria for causation were not met. Chronic asthma and tuberculosis are associated with irreversible loss of lung function, but there remains uncertainty about whether there are important phenotypic differences compared with COPD as it is typically encountered in clinical settings.

CONCLUSIONS

In public health terms, a substantive burden of COPD is attributable to risk factors other than smoking. To prevent COPD-related disability and mortality, efforts must focus on prevention and cessation of exposure to smoking and these other, less well-recognized risk factors.

Transforming growth factor-beta1 in asthmatic airway smooth muscle enlargement: is fibroblast growth factor-2 required?

Enlargement of airway smooth muscle (ASM) tissue around the bronchi/bronchioles is a histopathological signature of asthmatic airway remodelling and has been suggested to play a critical role in the increased lung resistance and airway hyperresponsiveness seen in asthmatic patients. The pleiotropic cytokine, TGF-beta1, is believed to contribute to several aspects of asthmatic airway remodelling and is known to influence the growth of many cell types. Increased TGF-beta1 expression/signalling and ASM growth have been shown to occur concurrently in animal models of asthma. Abundant studies further substantiate this association by showing that therapeutic strategies that reduce or prevent TGF-beta1 overexpression/signalling lead to a parallel decrease or prevention of ASM enlargement. Finally, recent findings have supported a direct link of causality between TGF-beta1 overexpression/signalling and the overgrowth of ASM tissue. To follow-up on these in vivo studies, many investigators have pursued detailed investigation of ASM in cell culture conditions, assessing the direct role of TGF-beta1 on cellular proliferation and/or hypertrophy. Inconsistencies among the in vitro studies suggest that the effect of TGF-beta1 on ASM cell proliferation/hypertrophy is contextual. A hypothesis focusing on fibroblast growth factor-2 is presented at the end of this review, which could potentially reconcile the apparent discrepancy between the conflicting in vitro findings with the consistent in vivo finding that TGF-beta1 is required for ASM enlargement in asthma.

Growing old with asthma: what are the changes and challenges?

Asthma is a disease that affects approximately 7% of adults residing in the USA; the prevalence is even greater in children and approaches 10%. The CDC has reported that the overall prevalence of lifetime asthma is 10.5%. New-onset asthma is most often seen in children and is associated with atopy; however, the majority of patients will experience a remission during adolescence. Many former asthmatics will have a reoccurrence of their disease in adulthood and asthma may persist thereafter for a lifetime. New-onset asthma may also begin later in life and remission is uncommon. The burden of asthma is therefore high in the geriatric population and healthcare utilization and mortality from asthma is excessive in this age group. There are many differences with asthma occurring in older adults when compared with younger asthmatics. This includes the frequency of medical comorbidities, the presence in many patients of fixed airflow obstruction that resembles chronic obstructive pulmonary disease, and the lack of perception of dyspnea that may delay effective medical care. Despite these and other differences, the pathophysiology and clinical presentation of asthma in the elderly is similar to that in younger asthmatics and attention to the unique features of aging can lead to improved outcomes in this age group.

A novel CC-chemokine receptor 3 antagonist, Ki19003, inhibits airway eosinophilia and subepithelial/peribronchial fibrosis induced by repeated antigen challenge in mice

CC-chemokine receptor 3 (CCR3) is a chemokine receptor for which major ligands, CC-chemokine ligand (CCL) 11, CCL24, and CCL26, are known to be involved in chemotaxis for eosinophils. In the present study, we evaluated the effect of a low molecular weight CCR3-receptor antagonist, Ki19003 (4-[[5-(2,4-dichlorobenzylureido)pentyl][1-(4-chlorophenyl)ethyl]amino]butanoic acid), on airway remodeling in a mouse model of allergic asthma. BALB/c mice were sensitized twice by intraperitoneal injection of ovalbumin (OA) and exposed daily to 1% OA for 3 weeks. Twenty-four hours after the final antigen challenge, bronchoalveolar lavage and histological examinations were carried out. Ki19003 clearly inhibited antigen-induced increase in the number of eosinophils in bronchoalveolar lavage fluid (BALF), but did not affect the number of other cell types examined in this study. Ki19003 also inhibited the increased production of transforming growth factor-beta1 in BALF and the amount of hydroxyproline in the lungs in a dose-dependent manner. Furthermore, Ki19003 significantly attenuated allergen-induced subepithelial and peribronchial fibrosis. These findings indicate that CCR3 antagonism prevents not only the infiltration of eosinophils into the airways but also the development of allergen-induced subepithelial and peribronchial fibrosis. Therefore, a CCR3 antagonist may be useful in the treatment of airway remodeling, especially subepithelial and peribronchial fibrosis, in allergic asthma.

Oncostatin M (OSM) is increased in asthma with incompletely reversible airflow obstruction

Oncostatin M, a unique member of the interleukin (IL)-6 cytokine family, is thought to be involved in airway remodeling. The expression of oncostatin M in the lower airways is unknown. The aim of this study was to measure the sputum expression of oncostatin M in patients with asthma with and without irreversible airflow obstruction. Induced sputum was collected from nonsmoking adults with stable asthma (n = 53), 31 with incomplete reversibility of airflow obstruction. Peripheral blood cells were isolated and stimulated with lipopolysaccharide in 10 participants with asthma and irreversible airflow obstruction. Oncostatin M protein levels were determined in supernatant, whereas RNA was extracted to determine Oncostatin M mRNA expression using real-time polymerase chain reaction (PCR). Oncostatin M mRNA expression and protein levels were significantly higher in the sputum of asthmatics with irreversible airflow obstruction. Sputum oncostatin M levels were highest in people with severe airflow obstruction and were localized to airway neutrophils and macrophages. Peripheral blood neutrophils released more oncostatin M when stimulated with lipopolysaccharide compared with unstimulated neutrophils. Sputum oncostatin M is increased in asthma with irreversible airflow obstruction and is present in airway neutrophils and macrophages. Oncostatin M may link airway inflammation to remodeling in asthma.

Irreversible airway obstruction in asthma

Asthma is generally characterized by fully reversible airway obstruction. However, a significant proportion of asthma patients demonstrate an incomplete reversibility of airway obstruction (IRAO) despite optimal treatment and the absence of a significant smoking history. Such partially irreversible airway obstruction may be due to residual airway inflammation, particularly of the eosinophilic type, and structural changes. Risks factors for IRAO include reduced pulmonary function early in life, frequent exacerbations, smoking, continuing exposure to a sensitizing agent, and adult-onset asthma. IRAO is associated with increased disease severity and increased asthma-related morbidity and mortality. Optimal asthma control, including prevention of asthma exacerbations, smoking avoidance, and sufficient anti-inflammatory therapy, should be implemented in an effort to avoid an accelerated decline in lung function and the development or worsening of IRAO.

Effect of early versus late intervention with inhaled corticosteroids on airway wall thickness in patients with asthma

BACKGROUND AND OBJECTIVE

The aim of this study was to determine whether early versus late initiation of long-term inhaled corticosteroid (ICS) therapy decreases airway wall thickness in patients with asthma.

METHODS

One hundred and eighty-one patients with asthma not previously treated with ICS were given inhaled budesonide for 1 year. These patients were divided into five groups according to the duration of their asthma symptoms, which ranged from less than 1 year to more than 10 years. High-resolution CT images and post-bronchodilator FEV1 were examined before and 1 year after treatment.

RESULTS

Before treatment, airway wall thickness was increased relative to the duration of asthma. Disease severity improved with ICS treatment even in patients who had suffered asthma symptoms for more than 10 years. Post ICS treatment, airway wall thickness decreased in patients with a duration of symptoms less than 3 years, and a minor response was seen in patients with a duration of symptoms from 3 to 5 years. However, there was no change in airway wall thickness in patients who had suffered asthma for more than 5 years. Post-bronchodilator FEV1 improved only in patients who had suffered asthma for less than 3 years.

CONCLUSIONS

ICS therapy may improve asthma control in all asthma patients despite the disease duration, but early ICS treatment may be critical to reverse airway wall thickening associated with asthma.

Matrix metalloproteinase-1 polymorphism is associated with persistent airway obstruction in asthma in the Taiwanese population

BACKGROUND AND OBJECTIVE

Overexpression of matrix metalloproteinase (MMP)-1 has been demonstrated in asthma, and MMP polymorphisms are known to enhance disease susceptibility. We investigated whether MMP-1 polymorphism is associated with persistent airway obstruction in asthma in the Taiwanese population.

METHODS

A total of 131 unrelated Taiwanese subjects were enrolled, age-matched, and divided as follows: (1) those who had asthma with persistent airway obstruction with forced expiratory volume in 1 second (FEV(1)) and FEV(1)/forced vital capacity (FVC) values less than 75% predicted (n = 41); (2) those with asthma without airway obstruction with FEV(1) and FEV(1)/FVC values > or = 75% predicted (n = 47); and (3) normal control subjects (n = 43). All were genotyped for the 1G/2G polymorphism of MMP-1 promoter (-1607 bp).

RESULTS

1G genotypes of MMP-1 containing at least one 1G allele were found in asthmatic patients with persistent airway obstruction (OR = 3.696, 95% CI: 1.489-9.173, p = 0.027), but not in asthmatic patients without airway obstruction (OR = 2.065, 95% CI: 0.890-4.790, p = 0.091) when compared with homozygous 2G (2G/2G). The heterozygous 1G genotype (1G/2G) was more associated with persistent airway obstruction than homozygous 2G (2G/2G) (OR: 4.727, 95% CI: 1.759-12.703, p = 0.012). The adjusted risk estimate of 1G genotypes for asthmatics with persistent airway obstruction was 4.416 (95% CI: 1.651-11.812, p = 0.003).

CONCLUSION

1G genotypes of MMP-1 polymorphism are associated with asthma with persistent airway obstruction, and the heterozygous 1G genotype (1G/2G) poses the most susceptibility to persistent airway obstruction in asthma.

Airway smooth muscle in asthma

Airway smooth muscle plays a multifaceted role in the pathogenesis of asthma. We review the current understanding of the contribution of airway myocytes to airway inflammation, airway wall remodeling, and airflow obstruction in this prevalent disease syndrome. Together, these roles make airway smooth muscle an attractive target for asthma therapy.