Airway inflammation in asthma with incomplete reversibility of airflow obstruction

The Pathology of Asthma: What Is Obstructing Our View?

Despite the advent of sophisticated and efficient new biologics to treat inflammation in asthma, the disease persists. Even following treatment, many patients still experience the well-known symptoms of wheezing, shortness of breath, and coughing. What are we missing? Here we examine the evidence that mucus plugs contribute to a substantial portion of disease, not only by physically obstructing the airways but also by perpetuating inflammation. In this way, mucus plugs may act as an immunogenic stimulus even in the absence of allergen or with the use of current therapeutics. The alterations of several parameters of mucus biology, driven by type 2 inflammation, result in sticky and tenacious sputum, which represents a potent threat, first due to the difficulties in expectoration and second by acting as a platform for viral, bacterial, or fungal colonization that allows exacerbations. Therefore, in this way, mucus plugs are an overlooked but critical feature of asthmatic airway disease.

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.

Treatment response among asthmatic patients with and without reversible airflow limitations

Objectives

Asthma is a chronic airway disorder associated with variable airflow limitations, which are triggered by different stimuli. The reversibility of airflow limitations reflects patients' responses to the therapy with bronchodilators and improvements in airflow. This study aims to determine the treatment outcomes (improvements in forced expiratory volume in the first second (FEV1) and the number of asthma exacerbations) associated with the presence of airflow reversibility.

Methods

This retrospective cohort study included 154 adults (>18 years) who were diagnosed with asthma and had pulmonary function testing (PFT) at a tertiary care centre in KSA between January 1st, 2014 and May 31st, 2019. Smokers and patients with comorbidities or medications that could affect PFT were excluded from the analysis. Patients were classified as having a reversible airflow limitation when they exhibited a post-bronchodilator FEV1 increase of 12% and 200 mL. Exacerbations were defined as the need to use oral corticosteroids. Chi-square tests were used for comparative analyses.

Results

From our cohort, 42 patients exhibited reversibility. In contrast, 112 patients did not show any sign of reversibility. Asthmatics with baseline reversible airflow limitations experienced significant worsening of FEV1 during the follow-up period compared with those with no reversibility, showing a mean difference of 19.96 mL (p = 0.0206). There was no significant association between asthma reversibility and exacerbations (p = 0.23).

Conclusion

In our study, during the follow-up of patients with asthma, we found that the reversibility of airflow was associated with significantly worse FEV1, although this did not have a significant effect on exacerbations. Therefore, we recommend regular spirometry follow-ups, particularly for patients with significant airway reversibility.

Neutrophils in asthma: the good, the bad and the bacteria

Airway inflammation plays a key role in asthma pathogenesis but is heterogeneous in nature. There has been significant scientific discovery with regard to type 2-driven, eosinophil-dominated asthma, with effective therapies ranging from inhaled corticosteroids to novel biologics. However, studies suggest that approximately 1 in 5 adults with asthma have an increased proportion of neutrophils in their airways. These patients tend to be older, have potentially pathogenic airway bacteria and do not respond well to classical therapies. Currently, there are no specific therapeutic options for these patients, such as neutrophil-targeting biologics.Neutrophils comprise 70% of the total circulatory white cells and play a critical defence role during inflammatory and infective challenges. This makes them a problematic target for therapeutics. Furthermore, neutrophil functions change with age, with reduced microbial killing, increased reactive oxygen species release and reduced production of extracellular traps with advancing age. Therefore, different therapeutic strategies may be required for different age groups of patients.The pathogenesis of neutrophil-dominated airway inflammation in adults with asthma may reflect a counterproductive response to the defective neutrophil microbial killing seen with age, resulting in bystander damage to host airway cells and subsequent mucus hypersecretion and airway remodelling. However, in children with asthma, neutrophils are less associated with adverse features of disease, and it is possible that in children, neutrophils are less pathogenic.In this review, we explore the mechanisms of neutrophil recruitment, changes in cellular function across the life course and the implications this may have for asthma management now and in the future. We also describe the prevalence of neutrophilic asthma globally, with a focus on First Nations people of Australia, New Zealand and North America.

Sputum mast cell/basophil gene expression relates to inflammatory and clinical features of severe asthma

BACKGROUND

Mast cells (MCs) and basophils are important in asthma pathophysiology, however direct measurement is difficult, and clinical and inflammatory associations in severe asthma are poorly understood. Transcriptomic hallmarks of MCs/basophils may allow their measurement in sputum using gene expression.

OBJECTIVES

This study sought to develop and validate a sputum MC/basophil gene signature and investigate its relationship to inflammatory and clinical characteristics of severe asthma.

METHODS

A total of 134 candidate MC/basophil genes (identified by the Immunological Genome Project Consortium) were screened in sputum microarray for differential expression among control subjects (n = 18), patients with eosinophilic (n = 29), and patients with noneosinophilic asthma (n = 30). Candidate genes were validated by confirming correlation of gene expression with flow cytometry-quantified sputum MCs and basophils in a separate asthma cohort (n = 20). The validated gene signature was measured in a severe asthma cohort (n = 81), and inflammatory and clinical associations were tested.

RESULTS

Through microarray screening and subsequent validation, we found quantitative PCR gene expression of 8 targets correlated with sputum MCs/basophils: TPSAB1/TPSB2, CPA3, ENO2, GATA2, KIT, GPR56, HDC, SOCS2. In severe asthma, MC/basophil genes were associated with eosinophilic airway inflammation (GATA2, TPSB2, CPA3, GPR56, HDC, SOCS2), blood eosinophils (TPSB2, CPA3, GATA2, SOCS2, FCER1A, HDC), fractional exhaled NO (GATA2, SOCS2), decreased lung function (KIT, ENO2), and moderate exacerbation history (GATA2, SOCS2).

CONCLUSIONS

Quantitative PCR-based measures reflect varying sputum MC/basophil abundance, demonstrating associations of MCs/basophils with eosinophilic inflammation, spirometry and exacerbation history in severe asthma.

Asthma with Irreversible Airway Obstruction in Smokers and Nonsmokers: Links between Airway Inflammation and Structural Changes

BACKGROUND

The development of irreversible airway obstruction (IRAO) in asthma is related to lung/airway inflammatory and structural changes whose characteristics are likely influenced by exposure to tobacco smoke.

OBJECTIVE

To investigate the interplay between airway and lung structural changes, airway inflammation, and smoking exposure in asthmatics with IRAO.

METHODS

We studied asthmatics with IRAO who were further classified according to their smoking history, those with ≥20 pack-years of tobacco exposure (asthmatics with smoking-related IRAO [AwS-IRAO]) and those with <5 pack-years of tobacco exposure (asthmatics with nonsmoking-related IRAO [AwNS-IRAO]). In addition to recording baseline clinical and lung function features, all patients had a chest computed tomography (CT) from which airway wall thickness was measured and quantitative and qualitative assessment of emphysema was performed. The airway inflammatory profile was documented from differential inflammatory cell counts on induced sputum.

RESULTS

Ninety patients were recruited (57 AwS-IRAO and 33 AwNS-IRAO). There were no statistically significant differences in the extent of emphysema and gas trapping between groups on quantitative chest CT analysis, although Pi10, a marker of airway wall thickness, was significantly higher in AwS-IRAO (p = 0.0242). Visual analysis showed a higher prevalence of emphysema (p = 0.0001) and higher emphysema score (p < 0.0001) in AwS-IRAO compared to AwNS-IRAO and distribution of emphysema was different between groups. Correlations between radiological features and lung function were stronger in AwS-IRAO. In a subgroup analysis, we found a correlation between airway neutrophilia and emphysematous features in AwS-IRAO and between eosinophilia and both airway wall thickness and emphysematous changes in AwNS-IRAO.

CONCLUSIONS

Although bronchial structural changes were relatively similar in smoking and nonsmoking patients with asthma and IRAO, emphysematous changes were more predominant in smokers. However, neutrophils in AwS-IRAO and eosinophils in AwNS-IRAO were associated with lung and airway structural changes.

Asthma-Chronic Obstructive Pulmonary Disease Overlap

Asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) defines a subgroup of patients with asthma who have persistent airflow obstruction or patients with COPD who may exhibit variable airflow limitation and/or evidence of type 2 inflammation. Additional investigations are needed to determine whether ACO represents a distinct disorder with unique underlying pathophysiology, whether ACO patients should be managed differently from those with asthma or COPD, and whether the diagnosis affects long-term outcomes. This article presents the data about the clinical features of ACO, the current information regarding the underlying pathophysiology of the syndrome, and current understanding of therapeutic options.

Asthma-COPD Overlap Phenotypes and Smoking :Comparative features of asthma in smoking or non-smoking patients with an incomplete reversibility of airway obstruction

The development of COPD features, such as an incomplete reversibility of airway obstruction (IRAO), in smoking or non-smoking asthmatic patients, a condition often named Asthma-COPD Overlap (ACO), has been recognized for decades. However, there is a need to know more about the sub-phenotypes of this condition according to smoking. This study aimed at comparing the clinical, physiological and inflammatory features of smoking and non-smoking asthmatic patients exhibiting IRAO. In this cross-sectional study, patients with an IRAO with (ACO, ≥20 pack-years) or without (NS-IRAO, <5 pack-years) significant smoking history completed questionnaires about asthma control (ACQ, score 0-6, 6 = better score) and quality of life (AQLQ, score 1-7, 1 = better score) and performed expiratory flows, lung volume and carbon monoxide diffusion capacity measurements. Blood sampling and induced sputum were obtained for systemic and lower airway inflammation assessment. A total of 115 asthmatic patients were included (75 ACO: age 61 ± 10 years, 60% women and 40 NS-IRAO: age 64 ± 9 years, 38% women). ACO patients had worse asthma control scores (1.8 ± 0.9 vs 1.4 ± 0.9, P = 0.02) and poorer asthma quality of life (5.3 ± 1.0 vs 5.9 ± 1.0, P = 0.003). In addition, ACO had higher residual volume (145 ± 45 vs 121 ± 29% predicted, P = 0.008) and a lower carbon monoxide diffusing capacity corrected for alveolar volume (90 ± 22 vs 108 ± 20% predicted, P = 0.0008). No significant differences were observed in systemic or lower airway inflammation. In conclusion, in smokers and non-smokers, the presence of IRAO in asthmatics is associated with different phenotypes that reflect the addition of smoking-induced changes to asthma physiopathology.

Expression of Inflammatory Mediators in Induced Sputum: Comparative Study in Asthma and COPD

Asthma and COPD are the most common obstructive lung diseases characterized by inflammation in the lower airways which contribute to airflow limitation. Different inflammatory mediators are thought to play a key role in these diseases. This study was conducted in 13 patients with asthma, 12 patients with COPD, and 13 control subjects. The expression of mRNA of IL-6, IL-13, CXCL8, TSLP, IL-33, IL-25, IL-17, ECP, mast cell tryptase, CCL24, and CCL26 was assessed in induced sputum cells by real time PCR. We found that CXCL8 was strongly related to the neutrophil percentage but differed significantly in COPD and asthma patients. The expression of IL-17 was lower in patients with atopic asthma compared to non-atopic asthma. The percentage of macrophages correlated negatively with the expression of mast cell tryptase and ECP in COPD, and with CXCL8 in asthma. The expression of ECP correlated negatively with the severity of COPD symptoms measured by CAT. We conclude that asthma and COPD demonstrate a significant overlap in the airway cytokine profile. Thus, differentiation between the two diseases is difficult as based on a single cytokine, which suggests the coexistence of phenotypes sharing a common cytokine network in these obstructive lung diseases.

Peripheral killer cells do not differentiate between asthma patients with or without fixed airway obstruction

OBJECTIVE

The three main types of killer cells - CD8⁺ T cells, NK cells and NKT cells - have been linked to asthma and chronic obstructive pulmonary disease (COPD). However, their role in a small subset of asthma patients displaying fixed airway obstruction (FAO), similar to that seen in COPD, has not been explored. The objective of the present study was to investigate killer cell numbers, phenotype and function in peripheral blood from asthma patients with FAO, asthma patients without FAO, and healthy individuals.

METHODS

Peripheral CD8⁺ T cells (CD8⁺CD3⁺CD56^-), NK cells (CD56⁺CD3^-) and NKT-like cells (CD56⁺CD3⁺) of 14 asthma patients with FAO (post-bronchodilator FEV/FVC <0.7, despite clinician-optimised treatment), 7 asthma patients without FAO (post-bronchodilator FEV/FVC ≥ 0.7), and 9 healthy individuals were studied.

RESULTS

No significant differences were seen between the number, receptor expression, MAPK signalling molecule expression, cytotoxic mediator expression, and functional cytotoxicity of peripheral killer cells from asthma patients with FAO, asthma patients without FAO and healthy individuals.

CONCLUSIONS

Peripheral killer cell numbers or functions do not differentiate between asthma patients with or without fixed airway obstruction.

Analysis of Asthma-Chronic Obstructive Pulmonary Disease Overlap Syndrome Defined on the Basis of Bronchodilator Response and Degree of Emphysema

RATIONALE

Despite the increasing recognition of asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS) as a clinical entity, it remains poorly characterized due to a lack of agreement on its definition and diagnostic criteria.

OBJECTIVES

The aim of this study was to use spirometry and computed tomography (CT) to help better define ACOS as well as to classify subjects with ACOS based on Global Initiative for Chronic Obstructive Lung Disease (GOLD) letter grade.

METHODS

We analyzed 10,192 subjects enrolled in the COPDGene Study. Subjects were non-Hispanic white or African American current or former smokers aged 45-80 years with at least a 10-pack-year smoking history. Subjects were categorized as having either ACOS with a bronchodilator response or chronic obstructive pulmonary disease with emphysema on the basis of spirometry, high-resolution CT, and a history of asthma or hay fever.

MEASUREMENTS AND MAIN RESULTS

Subjects with ACOS were younger (60.6 vs. 65.9 years old; P < 0.0001), more likely to be African American (26.8% vs. 14.4%; P < 0.0001), had a higher body mass index (29.6 vs. 25.1 kg/m(2); P < 0.0001), and were more likely to be current smokers (50.9% vs. 20.7%; P < 0.0001). The majority of subjects with ACOS were categorized as GOLD grade B. Despite less severe spirometry and CT findings in subjects with ACOS, there was no significant difference in severe or frequent exacerbations.

CONCLUSIONS

Bronchodilator responsiveness and degree of emphysema can help define ACOS. When defined on the basis of bronchodilator responsiveness and degree of emphysema, patients with ACOS represent a unique and high-risk group with distinct clinical features.

Do we really need asthma-chronic obstructive pulmonary disease overlap syndrome?

The association of asthma and chronic obstructive pulmonary disease (COPD) in the same patient, which is designated as mixed asthma-COPD phenotype or overlap syndrome (ACOS), remains a controversial issue. This is primarily because many conflicting aspects in the definition of ACOS remain, and it is extremely difficult to summarize the distinctive features of this syndrome. Furthermore, we are realizing that asthma, COPD, and ACOS are not single diseases but rather syndromes consisting of several endotypes and phenotypes and, consequently, comprising a spectrum of diseases. The umbrella term ACOS blurs the lines between asthma and COPD and allows an approach that simplifies therapy. However, this approach contradicts the modern concept according to which we must move toward more targeted and personalized therapies to treat patients with these diseases. Therefore we argue that the term ACOS must be abandoned and ultimately replaced when new phenotypes and underlying endotypes are identified and a new taxonomy of airway diseases is generated.

Asthma and chronic obstructive pulmonary disease overlap: asthmatic chronic obstructive pulmonary disease or chronic obstructive asthma?

Asthma and chronic obstructive pulmonary disease (COPD) are different disease entities. They are both clinical diagnoses, with diagnostic tools to discriminate between one another. However, especially in older patients (>55 years) it seems more difficult to differentiate between asthma and COPD. This has led to the definition of a new phenotype called asthma COPD overlap syndrome (ACOS). However, our understanding of ACOS is at a very preliminary stage, as most research has involved subjects with existing diagnoses of asthma or COPD from studies with different definitions for ACOS. This has led to different and sometimes opposing results between studies on several features of ACOS, also depending on the comparison with COPD alone, asthma alone or both, which are summarized in this review.We suggest not using the term ACOS for a patient with features of both asthma and COPD, but to describe a patient with chronic obstructive airway disease as completely as possible, with regard to characteristics that determine treatment response (e.g. eosinophilic inflammation) and prognosis (such as smoking status, exacerbation rate, fixed airflow limitation, hyperresponsiveness, comorbidities). This will provide a far more clinically relevant diagnosis, and would aid in research on treatment in more homogenous groups of patients with chronic airways obstruction. More research is certainly needed to develop more evidence-based definitions for this patient group and to evaluate biomarkers, which will help to further classify these patients, treat them more adequately and unravel the underlying pathophysiological mechanism.

Association between peripheral airway function and neutrophilic inflammation in asthma

BACKGROUND AND OBJECTIVE

Small airway dysfunction is associated with asthma severity and control, but its association with airway inflammation is unknown. The aim was to determine the association between sputum inflammatory cells and the site of small airway dysfunction, measured by multiple breath nitrogen washout in convection-dependent (Scond) and more peripheral diffusion-dependent (Sacin) airways.

METHODS

Fifty-three (20-67 years) subjects with asthma on inhaled corticosteroid (ICS) treatment were characterized by spirometry, Scond, Sacin and induced sputum differential counts. %Predicted values for Scond and Sacin were calculated from published reference equations to adjust for the effects of age. Univariate correlations were assessed using the Spearman test. Multivariate linear regressions were performed to account for potential confounders, including age, gender, disease duration, body mass index and ICS dose.

RESULTS

Sacin (%predicted) correlated significantly with neutrophil% (rs  = 0.33, P = 0.02), ICS dose (rs  = -0.28, P = 0.04) and age (rs  = 0.27, P = 0.05). In multivariate analysis, Sacin related only to neutrophil% (adjusted R(2)  = 0.18, P = 0.001). Scond (%predicted) correlated significantly only with eosinophil% (rs  = 0.39, P = 0.004). There was a trend for a negative relationship with ICS dose (rs  = -0.26, P = 0.06). In multivariate analysis, Scond related to eosinophil% and ICS dose independently (adjusted R(2)  = 0.12, P = 0.02).

CONCLUSIONS

Acinar and conductive airway dysfunction is associated with different inflammatory profiles in asthmatic airways, independently of the effects of age and disease duration. The association between acinar airway dysfunction and neutrophilic airway inflammation may have implications for asthma treatment.

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.

Managing older patients with coexistent asthma and chronic obstructive pulmonary disease: diagnostic and therapeutic challenges

Asthma and chronic obstructive pulmonary disease (COPD) are common obstructive airway diseases, especially among older people. These conditions are associated with a significant and increasing disease burden. The diagnosis and management of asthma and COPD in older populations are complex, and consequently clinicians are faced with many therapeutic and diagnostic challenges. Both aging and obstructive airway diseases are associated with complex co-morbidities and these coexisting illnesses confound management. Moreover, the age-related physiological changes that occur in the lungs may lead to airflow limitation, and this may be difficult to distinguish from an active disease state. In practice, management of asthma and COPD is informed by disease-specific clinical practice guidelines; however, most older people with these conditions are excluded from clinical trials that are designed to inform practice, creating major evidence gaps. Furthermore, seldom do clinical practice guidelines consider the complexities of management in older populations. The problems experienced by older people are complex and multifactorial and our approach to management must reflect these challenges. Opportunities exist to improve the management and outcomes for older people with obstructive airway disease and there is an urgent need for clinical trials to test management approaches in this population; current research must consider the challenges and evidence gaps that exist.

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.

Asthma in older adults

Asthma in older people is common and is characterised by underdiagnosis and undertreatment. Ageing is associated with unique issues that modify expression, recognition, and treatment of the disease. In particular, asthma and chronic obstructive pulmonary disease (COPD) both overlap and converge in older people. This concurrence, together with absence of precise diagnostic methods, makes diagnosis complex. A multidimensional assessment that addresses airway problems, comorbidities, risk factors, and management skills will draw attention to key needs for intervention. Increased attention to the complications of asthma and obstructive airway disease in older people is needed, specifically to develop effective systems of care, appropriate clinical practice guidelines, and a research agenda that delivers improved health outcomes.

Increased B cell-activating factor (BAFF) level in the sputum of children with asthma

Purpose

B cell-activating factor (BAFF) is a tumor-necrosis factor (TNF) superfamily member best known for its role in the survival and maturation of B cells. BAFF activity is observed in naïve cells as well as in effector/memory T cells. We aimed to explore whether BAFF in sputum is expressed at elevated levels in asthmatic airways and associated with eosinophilic inflammation, pulmonary function, and bronchial hyperresponsiveness in children.

Methods

One hundred and fifty-four asthmatic children and 98 healthy children were enrolled in the study. Sputum supernatants were collected and sputum BAFF and eosinophil cationic protein (ECP) levels were measured. We performed pulmonary function tests and methacholine challenge tests, while measuring total eosinophil count, total serum IgE, and serum ECP in all subjects.

Results

Asthmatic children had significantly higher levels of BAFF in induced sputum [26.50 (10.50-100.27) pg/mL] compared to healthy children [18.32 (7.68-44.63) pg/mL; P=0.011]. Sputum BAFF positively correlated with sputum eosinophils (γ=0.406, P<0.001) and sputum ECP (γ=0.789, P<0.001). Significant negative correlations were found between sputum BAFF and FEV1 (γ=-0.291, P<0.001) or post-bronchodilator FEV1 (γ=-0.334, P<0.001), whereas nonsignificant correlations were found between sputum BAFF and bronchial hyperresponsiveness, serum eosinophil count, and serum ECP.

Conclusion

These findings suggest that BAFF may play a role in childhood asthma, and BAFF levels in sputum could be a supportive marker that represents airway inflammation, especially eosinophilic inflammation.

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.

Asthma and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

In the clinical setting, patients who present with a combination of asthma and chronic obstructive pulmonary disease (COPD)-related traits are not uncommon. This review discusses recent advances in the characterization of the natural course, phenotypes, and molecular markers of cases with coexisting asthma and COPD and in the understanding of the nature of the link between these two conditions.

RECENT FINDINGS

Recent epidemiological evidence indicates that asthma accounts for a substantial proportion of cases of irreversible airflow limitation in the general population and that, in addition to the critical role of environmental exposures in adult age, alterations of developmental processes in childhood may also predispose patients with asthma to COPD later in life. Findings from clinical and experimental studies emphasize the existence of remarkable heterogeneity within the group of patients with coexisting asthma and COPD in terms of natural history of lung function, risk factors for disease progression, lung structural changes, and immunological profiles.

SUMMARY

The phenotypic complexity of cases with coexisting asthma and COPD challenges a rigid categorization of patients into existing diagnostic labels and suggests the importance of integrating clinical, functional, morphologic, immunological, and molecular assessments to tailor and optimize prevention and treatment.

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.

Determinants of bronchodilator responsiveness in patients with controlled asthma

Short-term bronchodilator responsiveness to an inhaled ss 2 adrenergic agonist was assessed by changes in forced expiratory volume in 1 second (FEV(1)) in nonsmoking adults with controlled asthma (mild disease, 20 patients; moderate disease, 20 patients; severe disease, 18 patients). Responsiveness correlated significantly with age and with percent of predicted FEV(1) (%FEV(1)) except in patients with severe asthma, who showed significantly less responsiveness than others. Thus, responsiveness is closely associated with degree of airflow limitation in patients with controlled asthma and is significantly influenced by severity of disease and by aging.

Structural changes in airway diseases: characteristics, mechanisms, consequences, and pharmacologic modulation

In airway diseases such as asthma and COPD, specific structural changes may be observed, very likely secondary to an underlying inflammatory process. Although it is still controversial, airway remodeling may contribute to the development of these diseases and to their clinical expression and outcome. Airway remodeling has been described in asthma in various degrees of severity, and correlations have been found between such features as increase in subepithelial collagen or proteoglycan deposits and airway responsiveness. Although the clinical significance of airway remodeling remains a matter of debate, it has been suggested as a potential target for treatments aimed at reducing asthma severity, improving its control, and possibly preventing its development. To date, drugs used to treat airway diseases have a little influence on airway structural changes. More research should be done to identify key changes, valuable treatments, and proper interventional timing to counteract these changes. The potential of novel therapeutic agents to reverse or prevent airway remodeling is an exciting avenue and warrants further evaluation.

Discriminating asthma and COPD based on bronchodilator data: an improvement of the methods

The degree of bronchodilation is usually expressed as a percentage of the predicted or baseline value. It has been shown that the relation between pre- and post-dilation lung function values is not adequately described by this approach: the sensitivity/specificity in separating asthmatics from cases of chronic obstructive pulmonary disease (COPD) could be improved. The alternative method we investigate is based on a logistic regression approach incorporating pre- and post-dilation lung function, age, sex and height. The discriminatory power of forced expiratory volume in one second (FEV1) increase as a percentage of the predicted or baseline FEV1 is compared to our approach using two databases containing bronchodilator data and diagnoses (asthma, chronic bronchitis or emphysema, the latter two grouped as (OPD). The increase as a percentage of the predicted or baseline approach and our alternative method show areas under the receiver operator curve (ROC) (males/females) of 0.552/0.629, 0.523/0.550 and 0.867/0.879 in one database. In the other database the same trend is present although less obvious: 0.628/0.730, 0.592/0.737 and 0.709/0.749. This increase in discriminatory power is obtained in the optimal use of all available information, especially age, which is not used in the increase of the predicted/baseline FEV1 rule.

Overlap of asthma and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Asthma and chronic obstructive pulmonary disease (COPD) are both defined by the presence of airflow obstruction, but they present distinguishing differences in terms of both risk factors and clinical phenotypes. Yet it is quite common in the clinical setting to observe patients with asthma showing COPD-like phenotypes, and vice versa, making it a priority to search for optimal prevention, treatment, and management strategies for these cases of coexisting lung obstructive diseases.

RECENT FINDINGS

Recent studies have provided further evidence of strong epidemiologic and clinical links between asthma and COPD. Adult subjects with active asthma are as much as 12 times more likely to acquire COPD over time than subjects with no active asthma. Signs identifying patients with asthma predisposed to developing COPD may already be present at the early stages of the disease, a finding with potential implications for prevention of COPD. In addition to spirometry and other pulmonary function tests (such as measurements of residual volume and diffusing capacity of the lung for carbon monoxide), recent evidence suggests that the assessment of type and degree of airway remodeling and the evaluation of inflammatory markers might prove useful in the future to characterize phenotypically patients with coexisting asthma and COPD.

SUMMARY

The nature of the association between asthma and COPD remains unclear and open to discussion. Further research is required to develop effective management algorithms for patients with multiple obstructive lung diseases, determine to what extent early treatment and optimal management of asthma may protect against progression into COPD, and identify genetic markers of individual susceptibility to specific lung disease phenotypes and pharmacologic treatments.