Clinical implications of airway hyperresponsiveness in COPD

Interleukin 31 receptor α promotes smooth muscle cell contraction and airway hyperresponsiveness in asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and goblet cell hyperplasia. Multiple cytokines, including IFNγ, IL-4, and IL-13 are associated with asthma; however, the mechanisms underlying the effects of these cytokines remain unclear. Here, we report a significant increase in the expression of IL-31RA, but not its cognate ligand IL-31, in mouse models of allergic asthma. In support of this, IFNγ, IL-4, and IL-13 upregulated IL-31RA but not IL-31 in both human and mice primary airway smooth muscle cells (ASMC) isolated from the airways of murine and human lungs. Importantly, the loss of IL-31RA attenuated AHR but had no effect on inflammation and goblet cell hyperplasia in mice challenged with allergens or treated with IL-13 or IFNγ. We show that IL-31RA functions as a positive regulator of muscarinic acetylcholine receptor 3 expression, augmenting calcium levels and myosin light chain phosphorylation in human and murine ASMC. These findings identify a role for IL-31RA in AHR that is distinct from airway inflammation and goblet cell hyperplasia in asthma.

Breathing better: A tech-monitored study of positive expiratory pressure and reading aloud for chronic obstructive pulmonary disease

BACKGROUND

Breathing exercises, such as diaphragmatic breathing and positive expiratory pressure (PEP), relieve breathlessness in people with chronic obstructive pulmonary disease (COPD).

AIM

This study aimed to investigate the effects of breathing exercises with PEP and reading aloud on vital signs, fatigue level, severity of dyspnoea and respiratory function parameters in patients with COPD.

DESIGN

The study followed a randomized controlled trial of COPD patients from a single hospital in eastern Turkey.

METHODS

The study included 103 patients who were randomly assigned to receive pre-reading exercises, breathing exercises with a PEP device or no intervention for 8 weeks.

RESULTS

The use of a PEP device improved oxygen saturation, forced expiratory volume in 1 s (FEV1 ) and FEV1 /forced vital capacity (FVC) values and reduced fatigue and dyspnoea severity. Reading aloud lowered the mean arterial pressure and reduced fatigue and dyspnoea severity.

CONCLUSION

The study concludes that PEP devices and reading aloud can improve respiratory function in patients with COPD. Additionally, reading aloud is an accessible, easy-to-implement and economically feasible method for treating COPD symptoms.

Advances in adrenergic receptors for the treatment of chronic obstructive pulmonary disease: 2023 update

INTRODUCTION

Strong scientific evidence and large experience support the use of β2-agonists for the symptomatic alleviation of COPD. Therefore, there is considerable effort in discovering highly potent and selective β2-agonists.

AREAS COVERED

Recent research on novel β2-agonists for the treatment of COPD. A detailed literature search was performed in two major databases (PubMed/MEDLINE and Scopus) up to September 2023."

EXPERT OPINION

Compounds that preferentially activate a Gs- or β-arrestin-mediated signaling pathway via β- adrenoceptors (ARs) are more innovative. Pepducins, which target the intracellular region of β2-AR to modulate receptor signaling output, have the most interesting profile from a pharmacological point of view. They stabilize the conformation of the β2-AR and influence its signaling by interacting with the intracellular receptor-G protein interface. New bifunctional drugs called muscarinic antagonist-β2 agonist (MABA), which have both muscarinic receptor (mAChR) antagonism and β2-agonist activity in the same molecule, are a new opportunity. However, all tested compounds have been shown to act predominantly as mAChR antagonists or β2-agonists. An intriguing idea is to utilize allosteric modulators that bind to β2-ARs at sites different than those bound by orthosteric ligands to augment or reduce the signaling transduced by the orthosteric ligand.

Interleukin 31 receptor alpha augments muscarinic acetylcholine receptor 3-driven calcium signaling and airway hyperresponsiveness in asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and goblet cell hyperplasia. Both Th1 and Th2 cytokines, including IFN-γ, IL-4, and IL-13 have been shown to induce asthma; however, the underlying mechanisms remain unclear. We observed a significant increase in the expression of IL-31RA, but not its cognate ligand IL-31 during allergic asthma. In support of this, IFN-γ and Th2 cytokines, IL-4 and IL-13, upregulated IL-31RA but not IL-31 in airway smooth muscle cells (ASMC). Importantly, the loss of IL-31RA attenuated AHR but had no effects on inflammation and goblet cell hyperplasia in allergic asthma or mice treated with IL-13 or IFN-γ. Mechanistically, we demonstrate that IL-31RA functions as a positive regulator of muscarinic acetylcholine receptor 3 expression and calcium signaling in ASMC. Together, these results identified a novel role for IL-31RA in AHR distinct from airway inflammation and goblet cell hyperplasia in asthma.

Novel antihyperglycaemic drugs and prevention of chronic obstructive pulmonary disease exacerbations among patients with type 2 diabetes: population based cohort study

OBJECTIVE

To determine whether the use of glucagon-like peptide 1 (GLP-1) receptor agonists, dipeptidyl peptidase 4 (DPP-4) inhibitors, and sodium-glucose co-transporter-2 (SGLT-2) inhibitors, separately, is associated with a decreased risk of exacerbations of chronic obstructive pulmonary disease among patients with chronic obstructive pulmonary disease and type 2 diabetes.

DESIGN

Population based cohort study using an active comparator, new user design.

SETTING

The United Kingdom Clinical Practice Research Datalink linked with the Hospital Episode Statistics Admitted Patient Care and Office for National Statistics databases.

PARTICIPANTS

Three active comparator, new user cohorts of patients starting the study drugs (GLP-1 receptor agonists, DPP-4 inhibitors, or SGLT-2 inhibitors) or sulfonylureas with a history of chronic obstructive pulmonary disease. The first cohort included 1252 patients starting GLP-1 receptor agonists and 14 259 starting sulfonylureas, the second cohort included 8731 patients starting DPP-4 inhibitors and 18 204 starting sulfonylureas, and the third cohort included 2956 patients starting SGLT-2 inhibitors and 10 841 starting sulfonylureas.

MAIN OUTCOME MEASURES

Cox proportional hazards models with propensity score fine stratification weighting were fitted to estimate hazard ratios and 95% confidence intervals of severe exacerbation of chronic obstructive pulmonary disease (defined as hospital admission for chronic obstructive pulmonary disease), separately for GLP-1 receptor agonists, DPP-4 inhibitors, and SGLT-2 inhibitors. Whether these drugs were associated with a decreased risk of moderate exacerbation (defined as a co-prescription of an oral corticosteroid and an antibiotic along with an outpatient diagnosis of acute chronic obstructive pulmonary disease exacerbation on the same day) was also assessed.

RESULTS

Compared with sulfonylureas, GLP-1 receptor agonists were associated with a 30% decreased risk of severe exacerbation (3.5 v 5.0 events per 100 person years; hazard ratio 0.70, 95% confidence interval 0.49 to 0.99) and moderate exacerbation (0.63, 0.43 to 0.94). DPP-4 inhibitors were associated with a modestly decreased incidence of severe exacerbation (4.6 v. 5.1 events per 100 person years; hazard ratio 0.91, 0.82 to 1.02) and moderate exacerbation (0.93, 0.82 to 1.07), with confidence intervals including the null value. Finally, SGLT-2 inhibitors were associated with a 38% decreased risk of severe exacerbation (2.4 v 3.9 events per 100 person years; hazard ratio 0.62, 0.48 to 0.81) but not moderate exacerbation (1.02, 0.83 to 1.27).

CONCLUSIONS

In this population based study, GLP-1 receptor agonists and SGLT-2 inhibitors were associated with a reduced risk of severe exacerbations compared with sulfonylureas in patients with chronic obstructive pulmonary disease and type 2 diabetes. DPP-4 inhibitors were not clearly associated with a decreased risk of chronic obstructive pulmonary disease exacerbations.

Diagnosis and Treatment of Early Chronic Obstructive Lung Disease (COPD)

Chronic obstructive lung disease (COPD) is responsible for substantial rates of mortality and economic burden, and is one of the most important public-health concerns. As the disease characteristics include irreversible airway obstruction and progressive lung function decline, there has been a great deal of interest in detection at the early stages of COPD during the “at risk” or undiagnosed preclinical stage to prevent the disease from progressing to the overt stage. Previous studies have used various definitions of early COPD, and the term mild COPD has also often been used. There has been a great deal of recent effort to establish a definition of early COPD, but comprehensive evaluation is still required, including identification of risk factors, various physiological and radiological tests, and clinical manifestations for diagnosis of early COPD, considering the heterogeneity of the disease. The treatment of early COPD should be considered from the perspective of prevention of disease progression and management of clinical deterioration. There has been a lack of studies on this topic as the definition of early COPD has been proposed only recently, and therefore further clinical studies are needed.

Oxidative Stress in Ozone-Induced Chronic Lung Inflammation and Emphysema: A Facet of Chronic Obstructive Pulmonary Disease

Oxidative stress plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD) caused by cigarette smoke and characterized by chronic inflammation, alveolar destruction (emphysema) and bronchiolar obstruction. Ozone is a gaseous constituent of urban air pollution resulting from photochemical interaction of air pollutants such as nitrogen oxide and organic compounds. While acute exposure to ozone induces airway hyperreactivity and neutrophilic inflammation, chronic ozone exposure in mice causes activation of oxidative pathways resulting in cell death and a chronic bronchial inflammation with emphysema, mimicking cigarette smoke-induced COPD. Therefore, the chronic exposure to ozone has become a model for studying COPD. We review recent data on mechanisms of ozone induced lung disease focusing on pathways causing chronic respiratory epithelial cell injury, cell death, alveolar destruction, and tissue remodeling associated with the development of chronic inflammation and AHR. The initial oxidant insult may result from direct effects on the integrity of membranes and organelles of exposed epithelial cells in the airways causing a stress response with the release of mitochondrial reactive oxygen species (ROS), DNA, and proteases. Mitochondrial ROS and mitochondrial DNA activate NLRP3 inflammasome and the DNA sensors cGAS and STING accelerating cell death pathways including caspases with inflammation enhancing alveolar septa destruction, remodeling, and fibrosis. Inhibitors of mitochondrial ROS, NLRP3 inflammasome, DNA sensor, cell death pathways, and IL-1 represent novel therapeutic targets for chronic airways diseases underlined by oxidative stress.

Application of Inflammatory Markers in Induced Sputum in Stable Chronic Obstructive Pulmonary Disease Patients with Positive Bronchodilation Tests

Positive bronchodilation (BD) tests can be noticed in some stable chronic obstructive pulmonary disease (COPD) patients. The characteristics of airway inflammation in this entity remain unclear. Our study aimed to identify the characteristics of airway inflammation in stable COPD patients with positive BD tests. The airway inflammation was assessed in 88 patients with stable COPD using the examination of induced sputum in the aftermath of lung function and BD tests. Cellular counts and the levels of molecular markers including eosinophil cationic protein (ECP), myeloperoxidase (MPO), interleukin-5 (IL-5), and IL-8 were assayed by Wright's stain, Immuno-CAP system, and ELISA, RT-PCR. Among the 88 patients with stable COPD, 20 (22.7%) showed positive BD tests. The values of eosinophils (4.7%±3.4%) and ECP (90.1±41.6 ng/mL) in induced sputum in stable COPD patients with positive BD tests were markedly elevated as compared with those in stable COPD patients with negative BD tests or in healthy controls (all P>0.05), but significantly lower than those in asthmatic patients (all P<0.01). The IL-5 in sputum supernatant was significantly decreased in stable COPD patients with positive BD tests as compared with the patients with asthma (12.5±7.8 vs. 48.2±26.0 ng/mL;.P<0.01). However, healthy controls exhibited similar concentrations of IL-5 in induced sputum with patients with stable COPD, whether with positive or negative BD tests (all P>0.05). Moreover, the values of neutrophils (61.8%±15.1%), MPO (574.0±111.8 ng/mL), and IL-8 (32.6±13.4 ng/mL) in induced sputum in stable COPD patients with positive BD tests were significantly higher than those in asthmatics or normal controls (all P<0.01). However, the values of the above inflammatory markers in induced sputum were similar among stable COPD patients with positive or negative BD tests (all P>0.05). The stable COPD patients with positive BD tests may present not only eosinophilic airway inflammation but also neutrophilic airway inflammation.

Airway responsiveness to methacholine and incidence of COPD: an international prospective cohort study

Background

It has been debated, but not yet established, whether increased airway responsiveness can predict COPD. Recognising this link may help in identifying subjects at risk.

Objective

We studied prospectively whether airway responsiveness is associated with the risk of developing COPD.

Methods

We pooled data from two multicentre cohort studies that collected data from three time points using similar methods (European Community Respiratory Health Survey and Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults). We classified subjects (median age 37 years, 1st–3rd quartiles: 29–44) by their level of airway responsiveness using quintiles of methacholine dose–response slope at the first examination (1991–1994). Then, we excluded subjects with airflow obstruction at the second examination (1999–2003) and analysed incidence of COPD (postbronchodilator FEV₁/FVC below the lower limit of normal) at the third examination (2010–2014) as a function of responsiveness, adjusting for sex, age, education, body mass index, history of asthma, smoking, occupational exposures and indicators of airway calibre.

Results

We observed 108 new cases of COPD among 4205 subjects during a median time of 9 years. Compared with the least responsive group (incidence rate 0.6 per 1000/year), adjusted incidence rate ratios for COPD ranged from 1.79 (95% CI 0.52 to 6.13) to 8.91 (95% CI 3.67 to 21.66) for increasing airway responsiveness. Similar dose–response associations were observed between smokers and non-smokers, and stronger associations were found among subjects without a history of asthma or asthma-like symptoms.

Conclusions

Our study suggests that increased airway responsiveness is an independent risk factor for COPD. Further research should clarify whether early treatment in patients with high responsiveness can slow down disease progression.

Increased Risk of Exacerbation in Asthma Predominant Asthma-Chronic Obstructive Pulmonary Disease Overlap Syndrome

Background

Obstructive airway disease patients with increased variability of airflow and incompletely reversible airflow obstruction are often categorized as having asthma–chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS). ACOS is heterogeneous with two sub-phenotypes: asthma-ACOS and COPD-ACOS. The objective of this study was to determine the difference in risk of exacerbation between the two sub-phenotypes of ACOS.

Methods

A total of 223 patients exhibiting incompletely reversible airflow obstruction with increased variability (spirometrically defined ACOS) were enrolled. These patients were divided into asthma-ACOS and COPD-ACOS according to their physician's diagnosis and smoking history of 10 pack-years. Within-group comparisons were made for asthma-ACOS versus COPD-ACOS and light smokers versus heavy smokers.

Results

Compared to patients with COPD-ACOS, patients with asthma-ACOS experienced exacerbation more often despite their younger age, history of light smoking, and better lung function. While the light-smoking group showed better lung function, they made unscheduled outpatient clinic visits more frequently. On multivariate analysis, asthma-ACOS and poor inhaler compliance were significantly associated with more than two unscheduled clinic visits during the previous year.

Conclusion

Spirometrically defined ACOS includes heterogeneous subgroups with different clinical features. Phenotyping of ACOS by physician's diagnosis could be significant in predicting future risk of exacerbation.

Spirometric variability in smokers: transitions in COPD diagnosis in a five-year longitudinal study

Background

Spirometrically-defined chronic obstructive pulmonary disease (COPD) is considered progressive but its natural history is inadequately studied. We hypothesized that spirometrically-defined COPD states could undergo beneficial transitions.

Methods

Participants in the Lovelace Smokers’ Cohort (n = 1553), primarily women, were longitudinally studied over 5 years. Spirometric states included normal postbronchodilator spirometry, COPD Stage I, Unclassified state, and COPD Stage II+, as defined by GOLD guidelines. Beneficial transitions included either a decrease in disease severity, including resolution of spirometric abnormality, or maintenance of non-diseased state. ‘All smokers’ (n = 1553) and subgroups with normal and abnormal spirometry at baseline (n = 956 and 597 respectively) were separately analyzed. Markov-like model of transition probabilities over an average follow-up period of 5 years were calculated.

Results

Among ‘all smokers’, COPD Stage I, Unclassified, and COPD Stage II+ states were associated with probabilities of 16, 39, and 22 % respectively for beneficial transitions, and of 16, 35, and 4 % respectively for resolution. Beneficial transitions were more common for new-onset disease than for pre-existing disease (p < 0.001). Beneficial transitions were less common among older smokers, men, or those with bronchial hyperresponsiveness but more common among Hispanics and smokers with excess weight.

Conclusions

This observational study of ever smokers, shows that spirometrically-defined COPD states, may not be uniformly progressive and can improve or resolve over time. The implication of these findings is that the spirometric diagnosis of COPD can be unstable. Furthermore, COPD may have a pre-disease state when interventions might help reverse or change its natural history.

Trial registration

NA.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-016-0468-7) contains supplementary material, which is available to authorized users.

Mitochondrial Transplantation Attenuates Airway Hyperresponsiveness by Inhibition of Cholinergic Hyperactivity

Increased cholinergic activity has been highlighted in the pathogenesis of airway hyperresponsiveness, and alternations of mitochondrial structure and function appear to be involved in many lung diseases including airway hyperresponsiveness. It is crucial to clarify the cause-effect association between mitochondrial dysfunction and cholinergic hyperactivity in the pathogenesis of airway hyperresponsiveness. Male SD rats and cultured airway epithelial cells were exposed to cigarette smoke plus lipopolysaccharide administration; mitochondria isolated from airway epithelium were delivered into epithelial cells in vitro and in vivo. Both the cigarette smoke plus lipopolysaccharide-induced cholinergic hyperactivity in vitro and the airway hyperresponsiveness to acetylcholine in vivo were reversed by the transplantation of exogenous mitochondria. The rescue effects of exogenous mitochondria were imitated by the elimination of excessive reactive oxygen species or blockage of muscarinic M₃ receptor, but inhibited by M receptor enhancer. Mitochondrial transplantation effectively attenuates cigarette smoke plus lipopolysaccharide-stimulated airway hyperresponsiveness through the inhibition of ROS-enhanced epithelial cholinergic hyperactivity.

Dynamics of airway response in lung microsections: a tool for studying airway-extra cellular matrix interactions

The biological configuration of extracellular matrix (ECM) plays a key role in how mechanical interactions of the airway with its parenchymal attachments affect the dynamics of airway responses in different pulmonary disorders including asthma, emphysema and chronic bronchitis. It is now recognized that mechanical interactions between airway tissue and ECM play a key regulatory role on airway physiology and kinetics that can lead to the reorganization and remodeling of airway connective tissue. A connective tissue is composed of airway smooth muscle cells (ASM) and the ECM, which includes variety of glycoproteins and therefore the extent of interactions between ECM and ASM affects airway dynamics during exacerbations of major pulmonary disorders. Measurement of the velocity and magnitude of airway closure or opening provide important insights into the functions of the airway contractile apparatus and the interactions with its surrounding connective tissues. This review highlights suitability of lung microsection technique in studying measurements of airway dynamics (narrowing/opening) and associated structural distortions in airway compartments.

Differences in the effects of Asian dust on pulmonary function between adult patients with asthma and those with asthma-chronic obstructive pulmonary disease overlap syndrome

BACKGROUND

Asian dust (AD) exposure exacerbates pulmonary dysfunction in patients with asthma. Asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS), characterized by coexisting symptoms of asthma and chronic obstructive pulmonary disease, is considered a separate disease entity. Previously, we investigated the effects of AD on pulmonary function in adult patients with asthma. Here, we present the findings of our further research on the differences in the effects of AD exposure on pulmonary function between patients with asthma alone and those with ACOS.

METHODS

Between March and May 2012, we conducted a panel study wherein we monitored daily peak expiratory flow (PEF) values in 231 adult patients with asthma. These patients were divided into 190 patients with asthma alone and 41 patients with ACOS in this study. Daily AD particle levels were measured using light detection and ranging systems. Two heavy AD days (April 23 and 24) were determined according to the Japan Meteorological Agency definition. A linear mixed model was used to estimate the association between PEF and AD exposure.

RESULTS

Increments in the interquartile range of AD particles (0.018 km(-1)) led to PEF changes of -0.50 L/min (95% confidence interval, -0.98 to -0.02) in patients with asthma alone and -0.11 L/min (-0.11 to 0.85) in patients with ACOS. The PEF changes after exposure to heavy AD were -2.21 L/min (-4.28 to -0.15) in patients with asthma alone and -2.76 L/min (-6.86 to 1.35) in patients with ACOS. In patients with asthma alone, the highest decrease in PEF values was observed on the heavy AD day, with a subsequent gradual increase over time.

CONCLUSION

Our results suggest that the effects of AD exposure on pulmonary function differ between patients with asthma alone and ACOS, with the former exhibiting a greater likelihood of decreased pulmonary function after AD exposure.

Genome-Wide Association Study Identification of Novel Loci Associated with Airway Responsiveness in Chronic Obstructive Pulmonary Disease

Increased airway responsiveness is linked to lung function decline and mortality in subjects with chronic obstructive pulmonary disease (COPD); however, the genetic contribution to airway responsiveness remains largely unknown. A genome-wide association study (GWAS) was performed using the Illumina (San Diego, CA) Human660W-Quad BeadChip on European Americans with COPD from the Lung Health Study. Linear regression models with correlated meta-analyses, including data from baseline (n = 2,814) and Year 5 (n = 2,657), were used to test for common genetic variants associated with airway responsiveness. Genotypic imputation was performed using reference 1000 Genomes Project data. Expression quantitative trait loci (eQTL) analyses in lung tissues were assessed for the top 10 markers identified, and immunohistochemistry assays assessed protein staining for SGCD and MYH15. Four genes were identified within the top 10 associations with airway responsiveness. Markers on chromosome 9p21.2 flanked by LINGO2 met a predetermined threshold of genome-wide significance (P < 9.57 × 10(-8)). Markers on chromosomes 3q13.1 (flanked by MYH15), 5q33 (SGCD), and 6q21 (PDSS2) yielded suggestive evidence of association (9.57 × 10(-8) < P ≤ 4.6 × 10(-6)). Gene expression studies in lung tissue showed single nucleotide polymorphisms on chromosomes 5 and 3 to act as eQTL for SGCD (P = 2.57 × 10(-9)) and MYH15 (P = 1.62 × 10(-6)), respectively. Immunohistochemistry confirmed localization of SGCD protein to airway smooth muscle and vessels and MYH15 to airway epithelium, vascular endothelium, and inflammatory cells. We identified novel loci associated with airway responsiveness in a GWAS among smokers with COPD. Risk alleles on chromosomes 5 and 3 acted as eQTLs for SGCD and MYH15 messenger RNA, and these proteins were expressed in lung cells relevant to the development of airway responsiveness.

Bronchial hyperresponsiveness, airway inflammation, and reversibility in patients with chronic obstructive pulmonary disease

BACKGROUND

Bronchial hyperresponsiveness (BHR), sputum eosinophilia, and bronchial reversibility are often thought to be a hallmark of asthma, yet it has been shown to occur in COPD as well.

OBJECTIVES

To evaluate the relationship between BHR, lung function, and airway inflammation in COPD patients.

METHODS

Thirty-one, steroid-free patients with stable, mild and moderate COPD were studied. The following tests were carried out: baseline lung function, reversibility, provocative dose of methacholine causing a 20% fall in forced expiratory volume in 1 second, a COPD symptom score, and sputum induction.

RESULTS

Twenty-nine patients completed the procedures. About 41.4% had BHR, 31.0% had increased sputum eosinophils, and 37.9% had bronchial reversibility. Some of the patients had only one of these characteristics while others had two or the three of them. Patients with BHR had higher sputum eosinophils than patients without BHR (P=0.046) and those with sputum eosinophils ≥3% had more exacerbations in the previous year and a higher COPD symptom score than patients with sputum eosinophils <3% (P=0.019 and P=0.031, respectively). In patients with BHR, the cumulative dose of methacholine was negatively related to the symptom score and the number of exacerbations in the previous year. When patients with bronchial reversibility were considered, bronchodilation was positively related to sputum eosinophils.

CONCLUSION

Our study showed that BHR, sputum eosinophilia, and bronchial reversibility were not clustered in one single phenotype of COPD but could be present alone or together. Of interest, BHR and airway eosinophilia were associated with clinical data in terms of exacerbations and symptoms. Further investigation is needed to clarify this topic.

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.

Effects of N-acetylcysteine in ozone-induced chronic obstructive pulmonary disease model

Introduction

Chronic exposure to high levels of ozone induces emphysema and chronic inflammation in mice. We determined the recovery from ozone-induced injury and whether an antioxidant, N-acetylcysteine (NAC), could prevent or reverse the lung damage.

Methods

Mice were exposed to ozone (2.5 ppm, 3 hours/12 exposures, over 6 weeks) and studied 24 hours (24h) or 6 weeks (6W) later. Nac (100 mg/kg, intraperitoneally) was administered either before each exposure (preventive) or after completion of exposure (therapeutic) for 6 weeks.

Results

After ozone exposure, there was an increase in functional residual capacity, total lung volume, and lung compliance, and a reduction in the ratio of forced expiratory volume at 25 and 50 milliseconds to forced vital capacity (FEV₂₅/FVC, FEV₅₀/FVC). Mean linear intercept (L_m) and airway hyperresponsiveness (AHR) to acetylcholine increased, and remained unchanged at 6W after cessation of exposure. Preventive NAC reduced the number of BAL macrophages and airway smooth muscle (ASM) mass. Therapeutic NAC reversed AHR, and reduced ASM mass and apoptotic cells.

Conclusion

Emphysema and lung function changes were irreversible up to 6W after cessation of ozone exposure, and were not reversed by NAC. The beneficial effects of therapeutic NAC may be restricted to the ASM.

Changed terms for drug payment influenced GPs' diagnoses and prescribing practice for inhaled corticosteroids

BACKGROUND

Inhaled glucocorticosteroids (ICS) are first-line anti-inflammatory treatment in asthma, but not in chronic obstructive pulmonary disease (COPD). To restrict ICS use in COPD to cases of severe disease, new terms for reimbursement of drug costs were introduced in Norway in 2006, requiring a diagnosis of COPD to be verified by spirometry.

OBJECTIVES

To describe how GPs' diagnoses and treatment of patients who used ICS before 2006 changed after a reassessment of the patients that included spirometry.

METHODS

From the shared electronic patient record system in one group practice, patients ≥ 50 years prescribed ICS (including in combination with long-acting beta2-agonists) during the previous year were identified and invited to a tailored consultation including spirometry to assure the quality of diagnosis and treatment. GPs' diagnoses and ICS prescribing patterns after this reassessment were recorded, retrospectively.

RESULTS

Of 164 patients identified, 112 were included. Post-bronchodilator spirometry showed airflow limitation indicating COPD in 55 patients. Of the 57 remaining patients, five had a positive reversibility test. The number of patients diagnosed with asthma increased (from 25 to 62) after the reassessment. A diagnosis of COPD was also more frequently used, whereas fewer patients had other pulmonary diagnoses. ICS was discontinued in 31 patients; 20 with mild to moderate COPD and 11 with normal spirometry.

CONCLUSION

Altered reimbursement terms for ICS changed GPs' diagnostic practice in a way that made the diagnoses better fit with the treatment given, but over-diagnosis of asthma could not be excluded. Spirometry was useful for identifying ICS overuse.

Phenotyping airways disease: an A to E approach

The airway diseases asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous conditions with overlapping pathophysiological and clinical features. It has previously been proposed that this heterogeneity may be characterized in terms of five relatively independent domains labelled from A to E, namely airway hyperresponsiveness (AHR), bronchitis, cough reflex hypersensitivity, damage to the airways and surrounding lung parenchyma, and extrapulmonary factors. Airway hyperresponsiveness occurs in both asthma and COPD, accounting for variable day to day symptoms, although the mechanisms most likely differ between the two conditions. Bronchitis, or airway inflammation, may be predominantly eosinophilic or neutrophilic, with different treatments required for each. Cough reflex hypersensitivity is thought to underlie the chronic dry cough out of proportion to other symptoms that can occur in association with airways disease. Structural changes associated with airway disease (damage) include bronchial wall thickening, airway smooth muscle hypertrophy, bronchiectasis and emphysema. Finally, a variety of extrapulmonary factors may impact upon airway disease, including rhinosinusitis, gastroesophageal reflux disease, obesity and dysfunctional breathing. This article discusses the A to E concept in detail and describes how this framework may be used to assess and treat patients with airway diseases in the clinic.

Brain-derived neurotrophic factor in cigarette smoke-induced airway hyperreactivity

Enhanced airway smooth muscle (ASM) contractility contributes to increased resistance to airflow in diseases such as bronchitis and asthma that occur in passive smokers exposed to secondhand smoke. Little information exists on the cellular mechanisms underlying such airway hyperreactivity. Sputum samples of patients with chronic sinusitis, bronchitis, and asthma show increased concentrations of growth factors called neurotrophins, including brain-derived growth factor (BDNF), but their physiological significance remains unknown. In human ASM, we tested the hypothesis that BDNF contributes to increased contractility with cigarette smoke exposure. The exposure of ASM to 1% or 2% cigarette smoke extract (CSE) for 24 hours increased intracellular calcium ([Ca(2+)](i)) responses to histamine, and further potentiated the enhancing effects of a range of BDNF concentrations on such histamine responses. CSE exposure increased the expression of the both high-affinity and low-affinity neurotrophin receptors tropomyosin-related kinase (Trk)-B and p75 pan-neurotrophin receptor, respectively. Quantitative ELISA showed that CSE increased BDNF secretion by human ASM cells. BDNF small interfering (si)RNA and/or the chelation of extracellular BDNF, using TrkB-fragment crystallizable, blunted the effects of CSE on [Ca(2+)](i) responses as well as the CSE enhancement of cell proliferation, whereas TrkB siRNA blunted the effects of CSE on ASM contractility. These data suggest that cigarette smoke is a potent inducer of BDNF and TrkB expression and signaling in ASM, which then contribute to cigarette smoke-induced airway hyperresponsiveness.

Bronchial responsiveness to dry air hyperventilation in smokers may predict decline in airway status using indirect methods

Background

Disabling respiratory symptoms and rapid decline of lung function may occur in susceptible tobacco smokers. Bronchial hyperresponsiveness (BHR) elicited by direct challenge methods predicts worse lung function outcomes. The aim of this study was to evaluate whether BHR to isocapnic hyperventilation of dry air (IHDA) was associated with rapid deterioration in airway status and respiratory symptoms.

Methods

One hundred twenty-eight smokers and 26 age- and sex-matched healthy individuals with no history of smoking were investigated. All subjects completed a questionnaire. Spirometry and impulse oscillometry (IOS) measurements were recorded before and after 4 min of IHDA. The tests were repeated after 3 years in 102 smokers and 11 controls.

Results

Eighty-five smokers (66 %) responded to the challenge with a ≥2.4-Hz increase in resonant frequency (F_res), the cutoff limit defining BHR, as recorded by IOS. They had higher F_res at baseline compared to nonresponding smokers [12.8 ± 3.2 vs. 11.5 ± 3.4 Hz (p < 0.05)] and lower FEV₁ [83 ± 13 vs. 89 ± 13 % predicted (p < 0.05)]. Multivariable logistic regression analysis indicated that wheezing (odds ratio = 3.7, p < 0.01) and coughing (odds ratio = 8.1, p < 0.05) were significantly associated with hyperresponsiveness. An increase in F_res was recorded after 3 years in responding smokers but not in nonresponders or controls. The difference remained when subjects with COPD were excluded.

Conclusions

The proportion of hyperresponsive smokers was unexpectedly high and there was a close association between wheezing and coughing and BHR. Only BHR could discriminate smokers with rapid deterioration of airway status from others.

Risk factors for chronic obstructive pulmonary disease in a European cohort of young adults

RATIONALE

Few studies have investigated the factors associated with the early inception of chronic obstructive pulmonary disease (COPD).

OBJECTIVES

We investigated COPD risk factors in an international cohort of young adults using different spirometric definitions of the disease.

METHODS

We studied 4,636 subjects without asthma who had prebronchodilator FEV(1)/FVC measured in the European Community Respiratory Health Survey both in 1991 to 1993 (when they were 20-44 yr old) and in 1999 to 2002. COPD was defined according to the Global Initiative for Chronic Obstructive Lung Disease fixed cut-off criterion (FEV(1)/FVC < 0.70), and two criteria based on the Quanjer and LuftiBus reference equations (FEV(1)/FVC less than lower limit of normal). COPD determinants were studied using two-level Poisson regression models.

MEASUREMENTS AND MAIN RESULTS

COPD incidence ranged from 1.85 (lower limit of normal [Quanjer]) to 2.88 (Global Initiative for Chronic Obstructive Lung Disease) cases/1,000/yr. Although about half of the cases had smoked less than 20 pack-years, smoking was the main risk factor for COPD, and it accounted for 29 to 39% of the new cases during the follow-up. Airway hyperresponsiveness was the second strongest risk factor (15-17% of new cases). Other determinants were respiratory infections in childhood and a family history of asthma, whereas the role of sex, age, and of being underweight largely depended on the definition of COPD used.

CONCLUSIONS

COPD may start early in life. Smoking prevention should be given the highest priority to reduce COPD occurrence. Airway hyperresponsiveness, a family history of asthma, and respiratory infections in childhood are other important determinants of COPD. We suggest the need for a definition of COPD that is not exclusively based on spirometry.