Chronic obstructive pulmonary disease (COPD) is the currently favoured name for the diseases formerly known as emphysema and bronchitis. COPD has been recognized for more than 200 years. Its cardinal symptoms are cough, phlegm and dyspnea, and its pathology is characterized by enlarged airspaces and obstructed airways. In the 19th century, the diagnosis of COPD depended on its symptoms and signs of a hyperinflated chest, and reduced expiratory breath sounds. The airflow obstruction evident on spirometry was identified in that century, but did not enter into clinical practice. Bronchitis, and the mechanical forces required to overcome its obstruction, was believed to be responsible for emphysema, although the inflammation present was recognized. The causes of bronchitis, and hence emphysema, included atmospheric and domestic air pollution, as well as dusty occupations. Cigarette smoking only became recognized as the dominant cause in the 20th century. The lessons learned of the risks for COPD in 19th-century Britain are very pertinent to the world today.
Bronchitis; COPD; Cotton; Emphysema; Pollution; Tobacco
Cigarette smoke exposure is the major cause of chronic obstructive pulmonary disease (COPD). However, only a minority of smokers develop significant COPD, and patients with asthma or asthma-like airway hyperresponsiveness or eosinophilia experience accelerated loss of lung function after cigarette smoke exposure. Pulmonary inflammation is a characteristic feature of lungs from patients with COPD. Surprisingly, the mediators of this inflammation and their contributions to the pathogenesis and varied natural history of COPD are not well defined. Here we show that IL-13, a critical cytokine in asthma, causes emphysema with enhanced lung volumes and compliance, mucus metaplasia, and inflammation, when inducibly overexpressed in the adult murine lung. MMP-2, -9, -12, -13, and -14 and cathepsins B, S, L, H, and K were induced by IL-13 in this setting. In addition, treatment with MMP or cysteine proteinase antagonists significantly decreased the emphysema and inflammation, but not the mucus in these animals. These studies demonstrate that IL-13 is a potent stimulator of MMP and cathepsin-based proteolytic pathways in the lung. They also demonstrate that IL-13 causes emphysema via a MMP- and cathepsin-dependent mechanism(s) and highlight common mechanisms that may underlie COPD and asthma.
This review proposes a critical reassessment (based entirely on published evidence) of the following seven common beliefs about chronic obstructive pulmonary disease (COPD): (1) COPD is one disease. (2) There is a valid definition for COPD. (The current definition includes cases of irreversible asthma and bronchiectasis, and occasionally, other obstructive lung conditions). (3) Irreversible asthma in smokers and COPD cannot be differentiated. (4) A “chronic bronchitis” form of COPD exists and is characterized by blue bloater status and normal carbon monoxide diffusion studies. (5) Phenotyping has no bearing on medication choice in COPD. (6) Computerized scoring of lung attenuation on CT scans can diagnose emphysema. (Emphysema scores overlap in irreversible asthma and COPD); however, qualitative visual changes may be useful for differentiation. (7) A definable entity called the overlap (of COPD and asthma) syndrome exists. Conflict over the abovementioned points denies patients proper phenotype-guided therapy and encourages a multidrug approach to COPD management. The recently coined term, overlap syndrome, invites a double-barreled therapy aimed at asthma and COPD, despite the absence of any agreement about how to define the syndrome and the lack of any related drug trials (in the area of inhaled corticosteroids). A diagnosis of COPD is associated with high morbidity and escalating costs, suggesting the need for a thorough new examination of the evidence.
asthma; computerized tomography; COPD; global initiative for chronic obstructive lung disease; overlap syndrome
Patients with bronchitis type of chronic obstructive pulmonary disease (COPD) have raised vascular endothelial growth factor (VEGF) levels in induced sputum. This has been associated with the pathogenesis of COPD through apoptotic and oxidative stress mechanisms. Since, chronic airway inflammation is an important pathological feature of COPD mainly initiated by cigarette smoking, aim of this study was to assess smoking as a potential cause of raised airway VEGF levels in bronchitis type COPD and to test the association between VEGF levels in induced sputum and airway inflammation in these patients.
14 current smokers with bronchitis type COPD, 17 asymptomatic current smokers with normal spirometry and 16 non-smokers were included in the study. VEGF, IL-8, and TNF-α levels in induced sputum were measured and the correlations between these markers, as well as between VEGF levels and pulmonary function were assessed.
The median concentrations of VEGF, IL-8, and TNF-α were significantly higher in induced sputum of COPD patients (1,070 pg/ml, 5.6 ng/ml and 50 pg/ml, respectively) compared to nonsmokers (260 pg/ml, 0.73 ng/ml, and 15.4 pg/ml, respectively, p < 0.05) and asymptomatic smokers (421 pg/ml, 1.27 ng/ml, p < 0.05, and 18.6 pg/ml, p > 0.05, respectively). Significant correlations were found between VEGF levels and pack years (r = 0.56, p = 0.046), IL-8 (r = 0.64, p = 0.026) and TNF-α (r = 0.62, p = 0.031) levels both in asymptomatic and COPD smokers (r = 0.66, p = 0.027, r = 0.67, p = 0.023, and r = 0.82, p = 0.002, respectively). No correlation was found between VEGF levels in sputum and pulmonary function parameters.
VEGF levels are raised in the airways of both asymptomatic and COPD smokers. The close correlation observed between VEGF levels in the airways and markers of airway inflammation in healthy smokers and in smokers with bronchitis type of COPD is suggestive of VEGF as a marker reflecting the inflammatory process that occurs in smoking subjects without alveolar destruction.
Patients with chronic obstructive pulmonary disease (COPD) exhibit dominant features of chronic bronchitis, emphysema, and/or asthma, with a common phenotype of airflow obstruction. COPD pulmonary physiology reflects the sum of pathological changes in COPD, which can occur in large central airways, small peripheral airways, and the lung parenchyma. Quantitative or high-resolution computed tomography is used as a surrogate measure for assessment of disease progression. Different biological or molecular markers have been reported that reflect the mechanistic or pathogenic triad of inflammation, proteases, and oxidants and correspond to the different aspects of COPD histopathology. Similar to the pathogenic triad markers, genetic variations or polymorphisms have also been linked to COPD-associated inflammation, protease–antiprotease imbalance, and oxidative stress. Furthermore, in recent years, there have been reports identifying aging-associated mechanistic markers as downstream consequences of the pathogenic triad in the lungs from COPD patients. For this review, the authors have limited their discussion to a review of mechanistic markers and genetic variations and their association with COPD histopathology and disease status.
senescence; apoptosis; chronic obstructive pulmonary disease; bronchitis; emphysema
Cigarette smoke has been connected to an array of chronic lung diseases and is a major source of morbidity and mortality. Active smoking is responsible for approximately 90% of lung cancer cases. In addition, cigarette smoke is associated with other chronic pulmonary diseases such as pulmonary edema, chronic bronchitis, and pulmonary emphysema, the last two also termed chronic obstructive pulmonary disease (COPD). Lung cancer and COPD are developed very frequently in chronic cigarette smokers. It has been known for some time that lung cancer incidence increases in patients with COPD. Even the existence of some low-grade emphysema without noticeable airflow obstruction is associated with significantly elevated risk of lung cancer. These recent clinical insights demand new thinking and exploration of novel mechanistic studies to fully understand these observations. Lung injury and repair involve cell death and hyperplasia of airway epithelial cells and infiltration of inflammatory cells. All of these occur simultaneously. The mechanisms of cell death and hyperplasia in the lung constitute two sides of the coin of lung injury and repair. However, most molecular studies in airway epithelial cells center on the mechanism(s) of either cell growth and proliferation or cell death and the ceramide-generating machinery that drives aberrant induction of apoptotic cell death. Very few address both sides of the coin as an outcome of cigarette smoke exposure, which is the focus of this review.
ceramide machinery; EGFR trafficking; cigarette smoke; lung injury; lung cancer
Chronic obstructive pulmonary disease (COPD) is characterized by an abnormal persistent inflammatory response to cigarette smoke. This noxious insult leads to emphysema and airway remodeling, manifested by squamous and mucous metaplasia of the epithelium, smooth muscle hypertrophy, and airway wall fibrosis. These pathologic abnormalities interact synergistically to cause progressive airflow obstruction. Although it has been accepted that the spectrum of COPD is vast, the reasons for the development of different phenotypes from the same exposure to cigarette smoke have not been determined. Furthermore, it is becoming increasingly clear that airways disease and emphysema often coexist in many patients, even with a clear clinical phenotype of either emphysema or chronic bronchitis. Recent studies have focused on the nature of the inflammatory response to cigarette smoke, the inflammatory cell lines responsible for COPD pathogenesis, and new biomarkers for disease activity and progression. New cytokines are being discovered, and the complex interactions among them are being unraveled. The inflammatory biomarker that has received the most attention is C-reactive protein, but new ones that have caught our attention are interleukin (IL)-6, tumor necrosis factor-α, IL-8, and IL-10. Further research should focus on how these new concepts in lung inflammation interact to cause the various aspects of COPD pathology.
chronic obstructive pulmonary disease; pathology; airway inflammation; emphysema; inflammatory biomarkers
Exposure to environmental tobacco smoke (ETS), which contains potent respiratory irritants, may lead to chronic airway inflammation and obstruction. Although ETS exposure appears to cause asthma in children and adults, its role in causing COPD has received limited attention in epidemiologic studies.
Using data from a population-based sample of 2,113 U.S. adults aged 55 to 75 years, we examined the association between lifetime ETS exposure and the risk of developing COPD.
Participants were recruited from all 48 contiguous U.S. states by random digit dialing. Lifetime ETS exposure was ascertained by structured telephone interview. We used a standard epidemiologic approach to define COPD based on a self-reported physician diagnosis of chronic bronchitis, emphysema, or COPD.
Higher cumulative lifetime home and work exposure were associated with a greater risk of COPD. The highest quartile of lifetime home ETS exposure was associated with a greater risk of COPD, controlling for age, sex, race, personal smoking history, educational attainment, marital status, and occupational exposure to vapors, gas, dusts, or fumes during the longest held job (OR 1.55; 95% CI 1.09 to 2.21). The highest quartile of lifetime workplace ETS exposure was also related to a greater risk of COPD (OR 1.36; 95% CI 1.002 to 1.84). The population attributable fraction was 11% for the highest quartile of home ETS exposure and 7% for work exposure.
ETS exposure may be an important cause of COPD. Consequently, public policies aimed at preventing public smoking may reduce the burden of COPD-related death and disability, both by reducing direct smoking and ETS exposure.
Pulmonary Disease; Chronic Obstructive; Chronic Bronchitis; Pulmonary Emphysema; Tobacco smoke pollution
Treatment of chronic diseases such as chronic obstructive pulmonary disease (COPD) is complicated by the presence of comorbidities. The objective of this analysis was to estimate the prevalence of comorbidity in COPD using nationally-representative data.
This study draws from a multi-year analytic sample of 14,828 subjects aged 45+, including 995 with COPD, from the National Health and Nutrition Examination Survey (NHANES), 1999–2008. COPD was defined by self-reported physician diagnosis of chronic bronchitis or emphysema; patients who reported a diagnosis of asthma were excluded. Using population weights, we estimated the age-and-gender-stratified prevalence of 22 comorbid conditions that may influence COPD and its treatment.
Subjects 45+ with physician-diagnosed COPD were more likely than subjects without physician-diagnosed COPD to have coexisting arthritis (54.6% vs. 36.9%), depression (20.6% vs. 12.5%), osteoporosis (16.9% vs. 8.5%), cancer (16.5% vs. 9.9%), coronary heart disease (12.7% vs. 6.1%), congestive heart failure (12.1% vs. 3.9%), and stroke (8.9% vs. 4.6%). Subjects with COPD were also more likely to report mobility difficulty (55.6% vs. 32.5%), use of >4 prescription medications (51.8% vs. 32.1), dizziness/balance problems (41.1% vs. 23.8%), urinary incontinence (34.9% vs. 27.3%), memory problems (18.5% vs. 8.8%), low glomerular filtration rate (16.2% vs. 10.5%), and visual impairment (14.0% vs. 9.6%). All reported comparisons have p < 0.05.
Our study indicates that COPD management may need to take into account a complex spectrum of comorbidities. This work identifies which conditions are most common in a nationally-representative set of COPD patients (physician-diagnosed), a necessary step for setting research priorities and developing clinical practice guidelines that address COPD within the context of comorbidity.
Asthma in older adults affects quality of life and results in a higher hospitalization rate and mortality. In common clinical practice, asthma in the elderly is underdiagnosed and undertreated or overdiagnosed and mistreated. The age-related reduction in perception of shortness of breath and the high incidence of comorbidities make the diagnosis and management more difficult and challenging for the physicians. Chronic obstructive pulmonary disease (COPD) is usually easy to distinguish from asthma, but sometimes the distinction from late-onset asthma in older patients, particularly in cigarette smokers, is difficult and may be impossible. Both diseases are characterized by the presence of airflow obstruction but have distinct pathogenesis, inflammatory pattern, and prognosis. The distinction between Asthma and COPD based simply on spirometric parameters is difficult especially in the elderly asthmatics. The combination of lung function testing, bronchial hyperresponsiveness (BHR) and atopy status, HRCT scans, and the newly developed biological techniques, allowing the assessment of biomarker profiles, could facilitate the distinction between these diseases.
Oxidative stress is associated with the pathogenesis of cigarette smoke related lung diseases, but longitudinal effects of smoking cessation on oxidant markers in the airways are unknown.
This study included 61 smokers; 21 with chronic bronchitis or COPD, 15 asthmatics and 25 asymptomatic smokers followed up for 3 months after smoking cessation. Fractional exhaled nitric oxide (FeNO), sputum neutrophil counts, sputum 8-isoprostane, nitrotyrosine and matrix metalloproteinase-8 (MMP-8) were investigated at baseline and 1 and 3 months after smoking cessation.
After 3 months 15 subjects had succeeded in quitting of smoking and in these subjects symptoms improved significantly. Unexpectedly, however, sputum neutrophils increased (p = 0.046) after smoking cessation in patients with chronic bronchitis/COPD. At baseline, the other markers did not differ between the three groups so these results were combined for further analysis. Sputum 8-isoprostane declined significantly during the follow-up at 3 months (p = 0.035), but levels still remained significantly higher than in non-smokers. The levels of FeNO, nitrotyrosine and MMP-8 did not change significantly during the 3 months after smoking cessation.
Whilst symptoms improve after smoking cessation, the oxidant and protease burden in the airways continues for months.
Concepts relating to the natural history of chronic obstructive pulmonary disease (COPD) arise most importantly from the classic study of Fletcher and colleagues (The Natural History of Chronic Bronchitis and Emphysema, Oxford University Press, New York, 1976). This study, which evaluated working English men over 8 years, was used to construct a proposed life-long natural history. Although this is a classic study that has greatly advanced understanding of COPD, it has a number of limitations. Its duration is relatively short compared with the duration of COPD, so it is more cross-sectional than longitudinal. It was unable to distinguish among varied “natural histories.” It assessed primarily the FEV1, and the natural history of other features of COPD is largely undescribed. With advances in understanding the clinical features of COPD and with the development of evaluating new tools to assess patients with COPD, longitudinal studies evaluating COPD in novel ways and for longer durations are needed.
lung function; severity; symptoms; biomarkers
Chronic obstructive pulmonary disease (COPD) has been consistently associated with increased risk of lung cancer. However, previous studies have had limited ability to determine whether the association is due to smoking.
The Environment And Genetics in Lung cancer Etiology (EAGLE) population-based case-control study recruited 2100 cases and 2120 controls, of whom 1934 cases and 2108 controls reported about diagnosis of chronic bronchitis, emphysema, COPD (chronic bronchitis and/or emphysema), or asthma more than 1 year before enrollment. We estimated odds ratios (OR) and 95% confidence intervals (CI) using logistic regression. After adjustment for smoking, other previous lung diseases, and study design variables, lung cancer risk was elevated among individuals with a history of chronic bronchitis (OR = 2.0, 95% CI = 1.5–2.5), emphysema (OR = 1.9, 95% CI = 1.4–2.8), or COPD (OR = 2.5, 95% CI = 2.0–3.1). Among current smokers, association between chronic bronchitis and lung cancer was strongest among lighter smokers. Asthma was associated with a decreased risk of lung cancer in males (OR = 0.48, 95% CI = 0.30–0.78).
These results suggest that the associations of personal history of chronic bronchitis, emphysema, and COPD with increased risk of lung cancer are not entirely due to smoking. Inflammatory processes may both contribute to COPD and be important for lung carcinogenesis.
Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease of the lung caused primarily by exposure to cigarette smoke. Clinically, it presents with progressive cough, sputum production, dyspnea, reduced exercise capacity, and diminished quality of life. Physiologically, it is characterized by the presence of partially reversible expiratory airflow limitation and hyperinflation. Pathologically, COPD is a multicomponent disease characterized by bronchial submucosal mucous gland hypertrophy, bronchiolar mucosal hyperplasia, increased luminal inflammatory mucus, airway wall inflammation and scarring, and alveolar wall damage and destruction. Management of COPD involves both pharmacological and nonpharmacological approaches. Bronchodilators and inhaled corticosteroids are recommended medications for management of COPD especially in more severe disease. Combination therapies containing these medications are now available for the chronic management of stable COPD. The US Food and Drug Administration, recently, approved the combination of budesonide/formoterol (160/4.5 μg; Symbicort™, AstraZeneca, Sweden) delivered via a pressurized meter dose inhaler for maintenance management of stable COPD. The combination also is delivered via dry powder inhaler (Symbicort™ and Turbuhaler™, AstraZeneca, Sweden) but is not approved for use in the United States. In this review, we evaluate available data of the efficacy and safety of this combination in patients with COPD.
inhaled steroid; bronchodilator; β2-agonist; lung function; quality of life; COPD exacerbations
The dioxins and dioxin-like compounds in cigarette smoke and environmental pollutants modulate immunological responses. These environmental toxicants are known to cause lung cancer but have also recently been implicated in allergic and inflammatory diseases such as bronchitis, asthma, and chronic obstructive pulmonary disease (COPD). In a novel pathway of this response, the activation of a nuclear receptor, arylhydrocarbon receptor (AhR), mediates the effects of these toxins through the arachidonic acid cascade, cell differentiation, cell-cell adhesion interactions, cytokine expression, and mucin production that are implicated in the pathogenesis and exacerbation of asthma/COPD. We have previously reported that human bronchial epithelial cells express AhR, and AhR activation induces mucin production through reactive oxygen species. This review discusses the role of AhR in asthma and COPD, focusing in particular on inflammatory and resident cells in the lung. We describe the important impact that AhR activation may have on the inflammation phase in the pathology of asthma and COPD. In addition, crosstalk of AhR signaling with other ligand-activated transcription factors such as peroxisome proliferator-activated receptors (PPARs) has been well documented.
Chronic obstructive pulmonary disease (COPD) kills approximately 2.8 million people each year, and more than 80% of COPD cases can be attributed to smoking. Leukocytes recruited to the lung contribute to COPD pathology by releasing reactive oxygen metabolites and proteolytic enzymes. In this work, we investigated where leukocytes enter the lung in the early stages of COPD in order to better understand their effect as a contributor to the development of COPD. We simultaneously evaluated the parenchyma and airways for neutrophil accumulation, as well as increases in the adhesion molecules and chemokines that cause leukocyte recruitment in the early stages of tobacco smoke induced lung disease. We found neutrophil accumulation and increased expression of adhesion molecules and chemokines in the bronchial blood vessels that correlated with the accumulation of leukocytes recovered from the lung. The expression of adhesion molecules and chemokines in other vascular beds did not correlate with leukocytes recovered in bronchoalveolar lavage fluid (BALF). These data strongly suggest leukocytes are recruited in large measure through the bronchial circulation in response to tobacco smoke. Our findings have important implications for understanding the etiology of COPD and suggest that pharmaceuticals designed to reduce leukocyte recruitment through the bronchial circulation may be a potential therapy to treat COPD.
To delineate the effect of COPD on a broad range of valued life activities (VLAs), compared to effects of other airways conditions.
We used cross-sectional data from a population-based, longitudinal study of U.S. adults with airways disease. Data are collected by telephone interview. VLA disability was compared among 3 groups defined by reported physicians’ diagnoses: COPD/emphysema, chronic bronchitis, and asthma. Multiple regression analyses were conducted to identify independent predictors of VLA disability.
About half of individuals with COPD were unable to perform at least one VLA; almost all reported at least one VLA affected. The impact among individuals with chronic bronchitis and asthma was less, but still notable: 74–84% reported at least one activity affected, and about 15% were unable to perform at least one activity. In general, obligatory activities were the least affected. Symptom measures and functional limitations were the strongest predictors of disability, independent of respiratory condition.
VLA disability is common among individuals with COPD. Obligatory activities are less affected than committed and discretionary activities. A focus on obligatory activities, as is common in disability studies, would miss a great deal of the impact of these conditions. Because individuals are often referred to pulmonary rehabilitation as a result of dissatisfaction with ability to perform daily activities, VLA disability may be an especially relevant outcome for rehabilitation.
disability; functioning; COPD; asthma; valued life activities
Occupational exposure is an important risk factor for chronic obstructive pulmonary disease (COPD), and silica dust is one of the most important occupational respiratory toxins. Epidemiological and pathological studies suggest that silica dust exposure can lead to COPD, even in the absence of radiological signs of silicosis, and that the association between cumulative silica dust exposure and airflow obstruction is independent of silicosis. Recent clinicopathological and experimental studies have contributed further towards explaining the potential mechanism through which silica can cause pathological changes that may lead to the development of COPD. In this paper we review the epidemiological and pathological evidence relevant to the development of COPD in silica dust exposed workers within the context of recent findings. The evidence surveyed suggests that chronic levels of silica dust that do not cause disabling silicosis may cause the development of chronic bronchitis, emphysema, and/or small airways disease that can lead to airflow obstruction, even in the absence of radiological silicosis.
Lung cancer and chronic obstructive pulmonary disease (COPD) share a common risk factor in cigarette smoking and a large portion of patients with lung cancer suffer from COPD synchronously. We therefore hypothesized that COPD is an independent risk factor for lung cancer. Our aim was to investigate the intrinsic linkage of COPD (or emphysema, chronic bronchitis and asthma) and lung cancer.
The present hospital-based case-control study included 1,069 patients with newly diagnosed lung cancer and 1,132 age frequency matched cancer-free controls. The odds ratios (ORs) for the associations between each previous pulmonary disease and lung cancer were estimated with logistic regression models, adjusting for age, sex, family history of cancer, BMI and pack year smoking. In meta-analysis, the pooled effects of previous pulmonary diseases were analyzed with random effects models; and stratification analyses were conducted on smoking status and ethnicity.
In the case-control study, previous COPD was associated with the odds for increased risk of lung cancer (OR = 1.29, 95% confidence interval [CI] = 1.00∼1.68); so were emphysema (OR = 1.55, 95%CI = 1.03∼2.32) and chronic bronchitis (OR = 1.22, 95%CI = 0.99∼1.67); while asthma was associated with odds for decreased risk of lung cancer (OR = 0.29, 95%CI = 0.16∼0.53). These associations were more pronounced in smokers (P<.05 for all strata), but not in non-smokers. In meta-analysis, 35 studies (22,010 cases and 44,438 controls) were identified. COPD was significantly associated with the odds for increased risk of lung cancer (pooled OR = 2.76; 95% CI = 1.85–4.11), so were emphysema (OR = 3.02; 95% CI = 2.41–3.79) and chronic bronchitis (OR = 1.88; 95% CI = 1.49–2.36); and these associations were more pronounced in smokers than in non-smokers (P<.001 respectively). No significant association was observed for asthma.
Previous COPD could increase the risk of lung cancer, especially in smokers.
BACKGROUND--Bronchial inflammation in chronic bronchitis has not been characterised as well as in asthma. The present study was undertaken to assess whether a characteristic pattern of bronchial inflammatory markers could be found in patients with chronic bronchitis. METHODS--Bronchoscopy with bronchial lavage was performed in 42 patients with chronic bronchitis and in 13 healthy controls. Twenty three of the patients had non-obstructive chronic bronchitis and 19 had chronic bronchitis and chronic obstructive pulmonary disease (COPD). Eighteen of the patients with bronchitis had recurrent infective exacerbations and 24 did not. Intrabronchial bacterial cultures were taken with a protected specimen brush. RESULTS--Increased activity of neutrophils, fibroblasts, and eosinophils was found in the patients with chronic bronchitis as assessed by the levels of myeloperoxidase (MPO) and interleukin-8 (IL-8), hyaluronan, and eosinophil cationic protein (ECP), respectively. The levels of tryptase did not differ from the controls. High correlations were found between the levels of MPO and IL-8, as well as ECP and IL-8. No differences were found between the patients with COPD and those with non-obstructive chronic bronchitis. CONCLUSIONS--Recruitment and activation of both neutrophils and eosinophils seem to be a characteristic of chronic bronchitis. This activation is associated with IL-8. The patients with intrabronchial cultures of Streptococcus pneumoniae had the highest individual levels of MPO, ECP, and IL-8 of all subjects in the study, indicating that colonisation with S pneumoniae could promote bronchial inflammation.
Cigarette smoking is the primary cause of Chronic Obstructive Pulmonary Disease (COPD), which is characterized by chronic inflammation of the airways and destruction of lung parenchyma. Repeated and sustained bacterial infections are clearly linked to disease pathogenesis (e.g., exacerbations) and a huge burden on health care costs. The airway epithelium constitutes the first line of host defense against infection and our previous study indicated that Fatty Acid Binding Protein 5 (FABP5) is down regulated in airway epithelial cells of smokers with COPD as compared to smokers without COPD. We hypothesized that cigarette smoke (CS) exposure down regulates FABP5, thus, contributing to a more sustained inflammation in response to bacterial infection. In this report, we show that FABP5 is increased following bacterial infection but decreased following CS exposure of primary normal human bronchial epithelial (NHBE) cells. The goal of this study was to address FABP5 function by knocking down or overexpressing FABP5 in primary NHBE cells exposed to CS. Our data indicate that FABP5 down regulation results in increased P. aeruginosa bacterial load and inflammatory cytokine levels (e.g., IL-8) and decreased expression of the anti-bacterial peptide, β defensin-2. On the contrary, FABP5 overexpression exerts a protective function in airway epithelial cells against P. aeruginosa infection by limiting the production of IL-8 and increasing the expression of β defensin-2. Our study indicates that FABP5 exerts immunomodulatory functions in the airway epithelium against CS exposure and subsequent bacterial infection through its modulation of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-γ activity. These findings support the development of FABP5/PPAR-γ-targeted therapeutic approach to prevent airway inflammation by restoring antimicrobial immunity during COPD exacerbations.
Lung cancer (LC) and chronic obstructive pulmonary disease (COPD) commonly coexist in smokers, and the presence of COPD increases the risk of developing LC. Cigarette smoke causes oxidative stress and an inflammatory response in lung cells, which in turn may be involved in COPD and lung cancer development. The aim of this study was to identify differential proteomic profiles related to oxidative stress response that were potentially involved in these two pathological entities. Protein content was assessed in the bronchoalveolar lavage (BAL) of 60 patients classified in four groups: COPD, COPD and LC, LC, and control (neither COPD nor LC). Proteins were separated into spots by two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and examined by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/TOF). A total of 16 oxidative stress regulatory proteins were differentially expressed in BAL samples from LC and/or COPD patients as compared with the control group. A distinct proteomic reactive oxygen species (ROS) protein signature emerged that characterized lung cancer and COPD. In conclusion, our findings highlight the role of the oxidative stress response proteins in the pathogenic pathways of both diseases, and provide new candidate biomarkers and predictive tools for LC and COPD diagnosis.
bronchoalveolar lavage; lung cancer; screening; biomarker; inflammation; proteomics; ROS; oxidative stress
Rationale: Wood smoke–associated chronic obstructive pulmonary disease (COPD) is common in women in developing countries but has not been adequately described in developed countries.
Objectives: Our objective was to determine whether wood smoke exposure was a risk factor for COPD in a population of smokers in the United States and whether aberrant gene promoter methylation in sputum may modify this association.
Methods: For this cross-sectional study, 1,827 subjects were drawn from the Lovelace Smokers' Cohort, a predominantly female cohort of smokers. Wood smoke exposure was self-reported. Postbronchodilator spirometry was obtained, and COPD outcomes studied included percent predicted FEV1, airflow obstruction, and chronic bronchitis. Effect modification of wood smoke exposure with current cigarette smoke, ethnicity, sex, and promoter methylation of lung cancer-related genes in sputum on COPD outcomes were separately explored. Multivariable logistic and poisson regression models were used for binary and rate-based outcomes, respectively.
Measurements and Main Results: Self-reported wood smoke exposure was independently associated with a lower percent predicted FEV1 (point estimate [± SE] −0.03 ± 0.01) and a higher prevalence of airflow obstruction and chronic bronchitis (odds ratio, 1.96; 95% confidence interval, 1.52–2.52 and 1.64 (95% confidence interval, 1.31–2.06, respectively). These associations were stronger among current cigarette smokers, non-Hispanic whites, and men. Wood smoke exposure interacted in a multiplicative manner with aberrant promoter methylation of the p16 or GATA4 genes on lower percent predicted FEV1.
Conclusions: These studies identify a novel link between wood smoke exposure and gene promoter methylation that synergistically increases the risk for reduced lung function in cigarette smokers.
wood smoke; cigarette smokers; airflow obstruction; gene promoter methylation in sputum DNA
The objective of the present study was to determine the association between CT phenotypes—emphysema by low attenuation area and bronchitis by airway wall thickness—and body composition parameters in a large cohort of subjects with and without COPD. In 452 COPD subjects and 459 subjects without COPD, CT scans were performed to determine emphysema (%LAA), airway wall thickness (AWT-Pi10), and lung mass. Muscle wasting based on FFMI was assessed by bioelectrical impedance. In both the men and women with COPD, FFMI was negatively associated with %LAA. FMI was positively associated with AWT-Pi10 in both subjects with and without COPD. Among the subjects with muscle wasting, the percentage emphysema was high, but the predictive value was moderate. In conclusion, the present study strengthens the hypothesis that the subgroup of COPD cases with muscle wasting have emphysema. Airway wall thickness is positively associated with fat mass index in both subjects with and without COPD.
To determine whether the self-reported diagnosis of adults who present to the emergency department (ED) with an acute exacerbation of either asthma or chronic obstructive pulmonary disease (COPD) is validated by medical record review.
This is cross-sectional study of 78 consecutive adults, 55 years and older, presenting to 3 EDs with symptoms suggestive of an exacerbation of asthma or COPD. We used current spirometric guidelines for a “spirometrically validated” diagnosis of COPD (eg, postbronchodilator forced expiratory volume in 1 second/forced ventilatory capacity b70%). Patients without office spirometry result were classified with COPD using clinical validation based on at least one of the following: primary care physician diagnosis of COPD, chronic bronchitis, or emphysema in the medical record or chest radiography, chest computed tomography, or arterial blood gas (ABG) diagnostic of COPD.
Among 60 patients who self-reported diagnosis of COPD, 98% (95% confidence interval, 89-100) had clinically validated or spirometrically validated COPD. In addition, 83% (95% confidence interval, 59-96) of patients who reported either asthma only or no respiratory disease had clinically validated or spirometrically validated COPD. In no case was the chest radiograph or the ABG useful as a stand-alone test in establishing the diagnosis of COPD.
Patients 55 years and older presenting to the ED with acute asthma or COPD, even those with clinical symptoms but no diagnosis of COPD, are likely to have COPD. Clinicians should maintain a high index of suspicion for COPD when older asthma patients deny COPD.