Risk factors for the development of chronic obstructive pulmonary disease

Impact of Acute Exacerbation and Its Phenotypes on the Clinical Outcomes of Chronic Obstructive Pulmonary Disease in Hospitalized Patients: A Cross-Sectional Study

Acute exacerbations of COPD (AECOPD) are clinically significant events having therapeutic and prognostic consequences. However, there is a lot of variation in its clinical manifestations described by phenotypes. The phenotypes of AECOPD were categorized in this study based on pathology and exposure. In our cross-sectional study, conducted between 1 January 2016 to 31 December 2020, the patients were categorized into six groups based on pathology: non-bacterial and non-eosinophilic; bacterial; eosinophilic; bacterial infection with eosinophilia; pneumonia; and bronchiectasis. Further, four groups were classified based on exposure to tobacco smoke (TS), biomass smoke (BMS), both, or no exposure. Cox proportional-hazards regression analyses were performed to assess hazard ratios, and Kaplan-Meier analysis was performed to assess survival, which was then compared using the log-rank test. The odds ratio (OR) and independent predictors of ward admission type and length of hospital stay were assessed using binomial logistic regression analyses. Of the 2236 subjects, 2194 were selected. The median age of the cohort was 67.0 (60.0 to 74.0) and 75.2% were males. Mortality rates were higher in females than in males (6.2% vs. 2.3%). AECOPD-B (bacterial infection) subjects [HR 95% CI 6.42 (3.06-13.46)], followed by AECOPD-P (pneumonia) subjects [HR (95% CI: 4.33 (2.01-9.30)], were at higher mortality risk and had a more extended hospital stay (6.0 (4.0 to 9.5) days; 6.0 (4.0 to 10.0). Subjects with TS and BMS-AECOPD [HR 95% CI 7.24 (1.53-34.29)], followed by BMS-AECOPD [HR 95% CI 5.28 (2.46-11.35)], had higher mortality risk. Different phenotypes have different impacts on AECOPD clinical outcomes. A better understanding of AECOPD phenotypes could contribute to developing an algorithm for the precise management of different phenotypes.

Assessment of pulmonary functions among traffic police personnel in Chennai city - A comparative cross-sectional study

Background:

Air pollution due to road traffic is a solemn health hazard and vehicular emissions due to huge population in the cities are the main reason for the air quality crisis. The study was conducted to assess the degree of impairment in lung function in traffic police personnel exposed to traffic pollution compared to less-exposed healthy subjects.

Materials and Methods:

This comparative cross-sectional study was conducted among 250 traffic police personnel, aged 20–55 years, working in Chennai city, as compared to a matched control group, consisting of 250 less-exposed subjects. Measurement of pulmonary function testing was done with an RMS Helio 401. Statistical analysis was carried out with R statistical software.

Results:

The traffic police personnel had significantly (P < 0.05) declined FEV1 and FEV1/FVC ratio and FEF 25–75% (L/s) as compared to controls. Traffic personnel with longer duration of exposure showed significantly (P < 0.05) reduced lung functions than those with shorter duration. We have found a significant negative correlation with all pulmonary function parameters such as FVC, FEV1, FEV1/FVC, PEFR, and FVC 25%–75% among the traffic police personnel.

Conclusion:

The impairment of pulmonary function among the traffic police personnel might be due to the effect of pollution by vehicular exhausts and they should be offered personal protective or preventive measures.

BRIP1 rs10744996C>A variant increases the risk of chronic obstructive pulmonary disease in the Mongolian population of northern China

NEW FINDINGS

What is the central question of this study? What is the role of breast cancer type 1 interacting protein C-terminal helicase 1 (BRIP1) polymorphism in chronic obstructive pulmonary disease (COPD)? What is the main finding and its importance? Variant rs10744996C>A of BRIP1 increases the susceptibility of the Mongolian population to COPD. The expression of BRIP1 was significantly reduced in cigarette smoke extract-treated airway epithelial cells.

ABSTRACT

Cigarette smoke is a major environmental pollutant that can induce DNA damage in humans. The development and progression of chronic obstructive pulmonary disease (COPD) are known to be related to the impairment of DNA repair. Breast cancer type 1 interacting protein C-terminal helicase 1 (BRIP1) plays an important role in DNA interstrand crosslink repair and double-strand break repair. However, the role of BRIP1 polymorphisms in COPD has not been previously described. In this study, whole genome sequencing was used to identify mutations, and single nucleotide polymorphism (SNP) genotyping was used to verify the selected SNPs. In addition the BRIP1 expression levels in 16HBE and A549 airway epithelial cells treated with or without cigarette smoke extract (CSE) were measured using western blotting and RT-qPCR. Rs10744996C>A in the 3'-untranslated region (3'UTR) of BRIP1 was then genotyped in 1296 COPD cases and 988 healthy control subjects from a Mongolian population in northern China. Significant differences in the distribution of rs10744996C>A variants between COPD and control groups (P = 0.001) were identified. Rs10744996C>A was found to be associated with significantly increased COPD risk (adjusted odds ratio = 1.60, 95% CI = 1.30-1.98, P < 0.0001). Additionally, rs10744996A genotype was found to interact with a family history of cancer and a history of x-ray exposure (P = 0.028 and 0.009, respectively). BRIP1 expression levels in 16HBE and A549 cells treated with CSE were significantly lower compared to the control treated cells. The rs10744996C>A variant of BRIP1 increased the COPD susceptibility of the Mongolian population cohort. BRIP1 mRNA and protein expression levels were significantly reduced in conjunction with CSE-induced DNA damage in 16HBE and A549 cells.

The Th17/Treg Cytokine Imbalance in Chronic Obstructive Pulmonary Disease Exacerbation in an Animal Model of Cigarette Smoke Exposure and Lipopolysaccharide Challenge Association

We proposed an experimental model to verify the Th17/Treg cytokine imbalance in COPD exacerbation. Forty C57BL/6 mice were exposed to room air or cigarette smoke (CS) (12 ± 1 cigarettes, twice a day, 30 min/exposure and 5 days/week) and received saline (50 µl) or lipopolysaccharide (LPS) (1 mg/kg in 50 µl of saline) intratracheal instillations. We analyzed the mean linear intercept, epithelial thickness and inflammatory profiles of the bronchoalveolar lavage fluid and lungs. We evaluated macrophages, neutrophils, CD4+ and CD8+ T cells, Treg cells, and IL-10+ and IL-17+ cells, as well as STAT-3, STAT-5, phospho-STAT3 and phospho-STAT5 levels using immunohistochemistry and IL-17, IL-6, IL-10, INF-γ, CXCL1 and CXCL2 levels using ELISA. The study showed that CS exposure and LPS challenge increased the numbers of neutrophils, macrophages, and CD4+ and CD8+ T cells. Simultaneous exposure to CS/LPS intensified this response and lung parenchymal damage. The densities of Tregs and IL-17+ cells and levels of IL-17 and IL-6 were increased in both LPS groups, while IL-10 level was only increased in the Control/LPS group. The increased numbers of STAT-3, phospho-STAT3, STAT-5 and phospho-STAT5+ cells corroborated the increased numbers of IL-17+ and Treg cells. These findings point to simultaneous challenge with CS and LPS exacerbated the inflammatory response and induced diffuse structural changes in the alveolar parenchyma characterized by an increase in Th17 cytokine release. Although the Treg cell differentiation was observed, the lack of IL-10 expression and the decrease in the density of IL-10+ cells observed in the CS/LPS group suggest that a failure to release this cytokine plays a pivotal role in the exacerbated inflammatory response in this proposed model.

Measuring the Prevalence of Diagnosed Chronic Obstructive Pulmonary Disease in the United States Using Data From the 2012-2014 National Health Interview Survey

OBJECTIVES

This study, measuring the prevalence of chronic obstructive pulmonary disease (COPD), examined (1) whether a single survey question asking explicitly about diagnosed COPD is sufficient to identify US adults with COPD and (2) how this measure compares with estimating COPD prevalence using survey questions on diagnosed emphysema and/or chronic bronchitis and all 3 survey questions together.

METHODS

We used data from the 2012-2014 National Health Interview Survey to examine different measures of prevalence among 7211 US adults who reported a diagnosed respiratory condition (ie, emphysema, chronic bronchitis, and/or COPD).

RESULTS

We estimated a significantly higher prevalence of COPD by using a measure accounting for all 3 diagnoses (6.1%; 95% CI, 5.9%-6.3%) than by using a measure of COPD diagnosis only (3.0%; 95% CI, 2.8%-3.1%) or a measure of emphysema and/or chronic bronchitis diagnoses (4.7%; 95% CI, 4.6%-4.9%). This pattern was significant among all subgroups examined except for non-Hispanic Asian adults. The percentage difference between measures of COPD was larger among certain subgroups (adults aged 18-39, Hispanic adults, and never smokers); additional analyses showed that this difference resulted from a large proportion of adults in these subgroups reporting a diagnosis of chronic bronchitis only.

CONCLUSIONS

With the use of self- or patient-reported health survey data such as the National Health Interview Survey, it is recommended that a measure asking respondents only about COPD diagnosis is not adequate for estimating the prevalence of COPD. Instead, a measure accounting for diagnoses of emphysema, chronic bronchitis, and/or COPD may be a better measure. Additional analyses should explore the reliability and validation of survey questions related to COPD, with special attention toward questions on chronic bronchitis.

Targeted high-throughput sequencing of candidate genes for chronic obstructive pulmonary disease

Background

Reduced lung function in patients with chronic obstructive pulmonary disease (COPD) is likely due to both environmental and genetic factors. We report here a targeted high-throughput DNA sequencing approach to identify new and previously known genetic variants in a set of candidate genes for COPD.

Methods

Exons in 22 genes implicated in lung development as well as 61 genes and 10 genomic regions previously associated with COPD were sequenced using individual DNA samples from 68 cases with moderate or severe COPD and 66 controls matched for age, gender and smoking. Cases and controls were selected from the Obstructive Lung Disease in Northern Sweden (OLIN) studies.

Results

In total, 37 genetic variants showed association with COPD (p < 0.05, uncorrected). Several variants previously discovered to be associated with COPD from genetic genome-wide analysis studies were replicated using our sample. Two high-risk variants were followed-up for functional characterization in a large eQTL mapping study of 1,111 human lung specimens. The C allele of a synonymous variant, rs8040868, predicting a p.(S45=) in the gene for cholinergic receptor nicotinic alpha 3 (CHRNA3) was associated with COPD (p = 8.8 x 10⁻³). This association remained (p = 0.003 and OR = 1.4, 95 % CI 1.1-1.7) when analysing all available cases and controls in OLIN (n = 1,534). The rs8040868 variant is in linkage disequilibrium with rs16969968 previously associated with COPD and altered expression of the CHRNA5 gene. A follow-up analysis for detection of expression quantitative trait loci revealed that rs8040868-C was found to be significantly associated with a decreased expression of the nearby gene cholinergic receptor, nicotinic, alpha 5 (CHRNA5) in lung tissue.

Conclusion

Our data replicate previous result suggesting CHRNA5 as a candidate gene for COPD and rs8040868 as a risk variant for the development of COPD in the Swedish population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0309-y) contains supplementary material, which is available to authorized users.

Childhood maltreatment as a risk factor for COPD: findings from a population-based survey of Canadian adults

Objective

The aim of this study was to examine the associations between childhood maltreatment (CM) and COPD in adulthood.

Methods

Data were from 15,902 respondents to the 2012 Canadian Community Health Survey – Mental Health. Multiple logistic regression models were used to examine associations between CM and COPD and the role of smoking and mental and substance use variables as mediators in associations.

Results

COPD in adulthood was related to CM, with associations differing by sex. Among females, COPD was related to childhood physical abuse (CPA), childhood sexual abuse, and childhood exposure to intimate partner violence, but in the fully adjusted models, the association with CPA did not persist. Among males, COPD was related to childhood exposure to intimate partner violence and severe and frequent CPA, but these associations did not persist in the fully adjusted models.

Conclusion

Results from this study establish CM as a risk factor for COPD in adulthood. A large part of the association is attributable to cigarette smoking, particularly for males. These findings underscore the importance of interventions to prevent CM as well as programs to assist victims of CM in dealing with tobacco addiction.

Association of IREB2 Gene rs2568494 Polymorphism with Risk of Chronic Obstructive Pulmonary Disease: A Meta-Analysis

Background

It is reported that the iron-responsive element-binding protein 2 (IREB2) gene rs2568494 polymorphism might be associated with COPD risk. The purpose of this meta-analysis was to collect all eligible studies to review the association between IREB2 gene rs2568494 polymorphism and susceptibility to COPD.

Material/Methods

We carried out a comprehensive document search of electronic databases of PubMed, MEDLIN, Web of Science, and included 4 eligible studies that examined the association between IREB2 rs2568494 polymorphism and COPD susceptibility. We performed a meta-analysis of these studies based on IREB2 rs2568494 genotypes.

Results

After meta-analysis with fixed or random effects, no significant associations were found under the heterozygote model (GG/GA; OR=0.908, 95%CI: 0.790–1.043; P=0.172), homozygote model (GG/AA; OR=0.880, 95%CI: 0.497–1.557; P=0.661), dominant model (GG/AA+GA; OR=0.941, 95%CI: 0.748–1.182; P=0.599), or allelic model (G/A; OR=0.953, 95%CI: 0.770–1.179; P=0.655). However, we found a significant correlation under the recessive model (AA/GA+GG; OR=1.384, 95%CI: 1.092–1.755; P=0.007).

Conclusions

The current results revealed that there was significant association between IREB2 gene rs2568494 polymorphism with susceptibility to COPD; the presence of allelic A might a genetic factor conferring susceptibility to COPD.

Early chronic obstructive pulmonary disease: definition, assessment, and prevention

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. COPD, however, is a heterogeneous collection of diseases with differing causes, pathogenic mechanisms, and physiological effects. Therefore a comprehensive approach to COPD prevention will need to address the complexity of COPD. Advances in the understanding of the natural history of COPD and the development of strategies to assess COPD in its early stages make prevention a reasonable, if ambitious, goal.

Role of transient receptor potential and pannexin channels in cigarette smoke-triggered ATP release in the lung

BACKGROUND

COPD is an inflammatory disease usually associated with cigarette smoking (CS) with an increasing global prevalence and no effective medication. Extracellular ATP is increased in the COPD affected lung and may play a key role in driving CS-induced airway inflammation, but the mechanism involved in ATP release has eluded researchers. Recently, the transient receptor potential (TRP) and pannexin-1 channels have been suggested to play a role in other experimental paradigms. Thus, the aim of this work is to investigate if these channels are involved in CS-induced ATP release in the lung.

METHODS

Primary human cells were exposed to CS and extracellular ATP levels measured. Mice were exposed to mainstream CS and airway inflammation assessed. TRPV1/4 mRNA expression was assessed in human lung parenchyma.

RESULTS

CS exposure caused a dose-related increase in ATP from primary airway bronchial epithelial cells. This was attenuated by blockers of TRPV1, TRPV4 and pannexin-1 channels. Parallel data was obtained using murine acute CS-driven model systems. Finally, TRPV1/4 mRNA expression was increased in lung tissue samples from patients with COPD.

CONCLUSIONS

Extracellular ATP is increased in the COPD affected lung and may play a key role in driving disease pathophysiology. These experiments uncover a novel mechanism which may be responsible for CS-induced ATP release. These findings highlight novel targets that could lead to the development of medicine to treat this devastating disease.

Common genetic determinants of lung function, subclinical atherosclerosis and risk of coronary artery disease

Chronic obstructive pulmonary disease (COPD) independently associates with an increased risk of coronary artery disease (CAD), but it has not been fully investigated whether this co-morbidity involves shared pathophysiological mechanisms. To identify potential common pathways across the two diseases, we tested all recently published single nucleotide polymorphisms (SNPs) associated with human lung function (spirometry) for association with carotid intima-media thickness (cIMT) in 3,378 subjects with multiple CAD risk factors, and for association with CAD in a case-control study of 5,775 CAD cases and 7,265 controls. SNPs rs2865531, located in the CFDP1 gene, and rs9978142, located in the KCNE2 gene, were significantly associated with CAD. In addition, SNP rs9978142 and SNP rs3995090 located in the HTR4 gene, were associated with average and maximal cIMT measures. Genetic risk scores combining the most robustly spirometry–associated SNPs from the literature were modestly associated with CAD, (odds ratio (OR) (95% confidence interval (CI₉₅) = 1.06 (1.03, 1.09); P-value = 1.5×10⁻⁴, per allele). In conclusion, our study suggests that some genetic loci implicated in determining human lung function also influence cIMT and susceptibility to CAD. The present results should help elucidate the molecular underpinnings of the co-morbidity observed across COPD and CAD.

The involvement of phospholipases A2 in asthma and chronic obstructive pulmonary disease

The increased morbidity, mortality, and ineffective treatment associated with the pathogenesis of chronic inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD) have generated much research interest. The key role is played by phospholipases from the A2 superfamily: enzymes which are involved in inflammation through participation in pro- and anti-inflammatory mediators production and have an impact on many immunocompetent cells. The 30 members of the A2 superfamily are divided into 7 groups. Their role in asthma and COPD has been studied in vitro and in vivo (animal models, cell cultures, and patients). This paper contains complete and updated information about the involvement of particular enzymes in the etiology and course of asthma and COPD.

What can genetics tell us about the cause of fixed airflow obstruction?

Chronic obstructive pulmonary disease (COPD) is a major cause of chronic morbidity and mortality worldwide with smoking being the most important risk factor of the disease. However, lung function and COPD are known to also have a genetic component and a deeper knowledge of the genetic architecture of the disease could lead to further understanding of predisposition to COPD and also to development of new therapeutic interventions. Genetic linkage studies and candidate gene association studies have not provided evidence to convincingly identify the genes underlying lung function or COPD. However, recent large genome-wide association studies (GWAS) including tens of thousands of individuals have identified 26 variants at different loci in the human genome that show robust association with quantitative lung function measures in the general population. A growing number of these variants are being shown to be associated with COPD. Following the identification of these new lung function loci, the challenge now lies in refining the signals to identify the causative variants underlying the association signals and relating these signals to the molecular pathways that underlie lung function.

Epidemiology and management of common pulmonary diseases in older persons

Pulmonary disease prevalence increases with age and contributes to morbidity and mortality in older patients. Dyspnea in older patients is often ascribed to multiple etiologies such as medical comorbidities and deconditioning. Common pulmonary disorders are frequently overlooked as contributors to dyspnea in older patients. In addition to negative impacts on morbidity and mortality, quality of life is reduced in older patients with uncontrolled, undertreated pulmonary symptoms. The purpose of this review is to discuss the epidemiology of common pulmonary diseases, namely pneumonia, chronic obstructive pulmonary disease, asthma, lung cancer, and idiopathic pulmonary fibrosis in older patients. We will review common clinical presentations for these diseases and highlight differences between younger and older patients. We will also briefly discuss risk factors, treatment, and mortality associated with these diseases. Finally, we will address the relationship between comorbidities, pulmonary symptoms, and quality of life in older patients with pulmonary diseases.

Increase of Th17 cells in peripheral blood of patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a progressive disorder characterized by an inflammatory response to cigarette smoke. A disorder in immune regulation contributing to the pathogenesis of COPD has been suggested, however, little is known about the involvement of CD4 (+) T cells. To determine the distribution of different CD4(+) T cell subsets in patients with COPD, current smokers without COPD (CS) and healthy subjects (HS), and its correlation with pulmonary function.

METHODS

Th1, Th2, Th17 and Treg, subsets, were quantified by flow cytometry in peripheral blood (PB) of 39 patients with COPD, 14 CS and 15 HS. Correlations were assessed with Spearman's rank test. The association between Th17 and lung function was evaluated with a multivariate logistic regression analysis.

RESULTS

An increase of Th17 cells (median 9.7% range 0.8-22.5%) was observed in patients with COPD compared with CS (median 2.8% range 0.8-10.6) and HS (median 0.6% range 0.4-1%, p < 0.0001). Th1 and Tregs subsets were also increased in COPD and CS compared to HS. Inverse correlations were found between Th17 with FEV(1)%p r = -0.57 and with FEV(1)/FVC r = -0.60, (p < 0.0001 for both comparison). In addition, increase of Th17 predicted the presence [OR 1.76 (CI 95% 1.25-2.49, p = 0.001)] and severity of airflow limitation [OR 1.13 (CI95% 1.02-1.25, p = 0.02)].

CONCLUSIONS

The increase of Th17 response and the lost of balance between CD4(+) T cell subsets, suggest a lack of regulation of the systemic inflammatory response that may contribute to pathogenesis in COPD patients.

The lung: the natural boundary between nature and nurture

Common lung diseases such as asthma, COPD, and pulmonary fibrosis cause significant morbidity and mortality in the U.S. and worldwide. Research investigating the mechanisms of disease etiology has clearly indicated that genetic attributes and environmental exposures each play important roles in the development of these diseases. Emerging evidence underscores the importance of the interplay between genetic predisposition and environmental factors in fully understanding the development of lung disease. Herein we discuss recent advances in knowledge and technology surrounding the role of genetics, the environment, and gene-environment interactions in these common lung diseases.

Chronic Obstructive Pulmonary Disease and Smoking Cessation

Chronic obstructive pulmonary disease (COPD) is a major and increasing cause of morbidity and mortality. Cigarette smoking is the most important risk factor for COPD, and smoking cessation is, in most cases, the most effective way of preventing the onset and progression of COPD. The purpose of the present article was to review the current state of interventions for smokers with COPD. Because 70% of smokers visit a physician annually, primary care providers play a key role in the counseling of all patients at every visit. If smoking cessation is achieved at an early stage of disease, it is associated with a decrease in pulmonary symptoms and improves prognosis and prolonged abstinence. The health benefits of smoking cessation are immediate and substantial, and interventions provided for smokers suggest that multiple modalities are needed. Smoking cessation counseling in combination with nicotine replacement therapy (NRT) appears to be the most effective modality followed by smoking cessation in combination with an antidepressant to enhance prolonged abstinence.

Targeted treatment in COPD: a multi-system approach for a multi-system disease

Chronic obstructive pulmonary disease is a varied condition when examined from a number of different perspectives including factors which influence disease development, pathological process and clinical features. There may be a complex interaction between the degree by which each of these processes influences the development of COPD and the subsequent clinical phenotype with which the patient presents. The varied host response and subsequent clinical phenotype has generated much interest in recent years. It is possible that failure of treatment to impact on mortality and reverse the disease process is because of the heterogeneous nature of the condition. Identification and targeted treatment of clinical and pathological phenotypes within the broad spectrum of COPD may therefore improve outcome. This article will review previous work which has attempted to phenotype COPD and identify if specific treatment for these phenotypes has been shown to be of benefit. It will examine the work on pathological processes and clinical manifestations, both pulmonary and systemic, and will focus on pharmacological therapies.

Genetics of chronic obstructive pulmonary disease: a succinct review, future avenues and prospective clinical applications

Chronic obstructive pulmonary disease (COPD) is influenced by genetic and environmental factors. A large number of candidate gene-association studies and genome-wide linkage scans have been conducted to elucidate the genetic architecture underlying this disease. The compilation of these studies clearly revealed the complex genetic nature of COPD. Multiple genes acting on specific environmental backgrounds are likely to be the tenet of this multifactorial disorder. Encouragingly, reproducible susceptibility genes, such as SERPINE2, were recently identified. Advances in genomic research offer unprecedented capabilities to interrogate the human genome and are likely to accelerate the discovery of new genes. A comprehensive catalogue of genes implicated in the pathogenesis of COPD has great potential to lead to the development of new therapies and explain interindividual response to treatment.

Respiratory morbidity attributed to auto-exhaust pollution in traffic policemen of Jaipur, India

AIMS

This study was conducted to evaluate pulmonary effects of traffic pollution on traffic police.

METHODS

The traffic police working in Jaipur city were given a predetermined respiratory health questionnaire, and their clinical profile and lung functions were measured.

RESULTS

This study showed that there were prominent respiratory symptoms and reduced forced expiratory volume in 1 second (FEV(1)) in subjects exposed to traffic pollution. When smokers were excluded, it showed a significant difference in FEV(1) data of non-smoking subjects exposed to traffic generated pollution and those not exposed. The difference observed was 95.3 +/- 13.6 versus 87.8 +/- 0.95%, respectively, and 95%CI = 4.420-10.517, p = 0.001.

CONCLUSIONS

Respiratory morbidity with respect to lung function tests is observed more in groups working in heavy traffic than the control group.

Optimizing economic outcomes in the management of COPD

Attention to COPD is increasing worldwide because its high prevalence, morbidity, and mortality present a challenging problem for all healthcare systems. The burden of COPD, which is usually measured in terms of progressive lung function decline, impact on patients' symptoms, patient's disability, and quality of life, together with the corresponding use of health care resources, is still a major aspect of the disease. Recommendations to treat COPD according to the most accepted guidelines have expanded in recent years even though COPD still remains unacceptably under-diagnosed and under-treated worldwide. Obviously, more severe degrees of COPD receive major attention both in terms of monitoring of clinical outcomes and of assessing the economic value of therapeutic interventions. The role of different strategies against COPD should be valued on the basis of their effectiveness in outcome optimization, which primarily depends on the efficacy of prevention activities and of early diagnosis programs. It is generally agreed that the main proportion of COPD burden still depends on the clinically uncontrolled disease and on its high exacerbation rate, which frequently leads to the patient hospitalization. In COPD, the effects of guideline recommendations have been only sporadically investigated in pharmaoeconomic terms, even though symptoms and disability have declined substantially; the corresponding improvement in quality of life, and a significant decrease in both direct and indirect costs have been proved to depend on appropriate rehabilitative and pharmacological long-term treatment of the disease. At present, more precise indices and more fitting outcomes are continuously sought and found in order to assess more effective strategies for controlling COPD.

Airway wall thickening and emphysema show independent familial aggregation in chronic obstructive pulmonary disease

RATIONALE

It is unclear whether airway wall thickening and emphysema make independent contributions to airflow limitation in chronic obstructive pulmonary disease (COPD) and whether these phenotypes cluster within families.

OBJECTIVES

To determine whether airway wall thickening and emphysema (1) make independent contributions to the severity of COPD and (2) show independent aggregation in families of individuals with COPD.

METHODS

Index cases with COPD and their smoking siblings underwent spirometry and were offered high-resolution computed tomography scans of the thorax to assess the severity of airway wall thickening and emphysema.

MEASUREMENTS AND MAIN RESULTS

A total of 3,096 individuals were recruited to the study, of whom 1,159 (519 probands and 640 siblings) had technically adequate high-resolution computed tomography scans without significant non-COPD-related thoracic disease. Airway wall thickness correlated with pack-years smoked (P < or = 0.001) and symptoms of chronic bronchitis (P < 0.001). FEV(1) (expressed as % predicted) was independently associated with airway wall thickness at a lumen perimeter of 10 mm (P = 0.0001) and 20 mm (P = 0.0013) and emphysema at -950 Hounsfield units (P < 0.0001). There was independent familial aggregation of both the emphysema (adjusted odds ratio, 2.1; 95% confidence interval, 1.1-4.0; P < or = 0.02) and airway disease phenotypes (P < 0.0001) of COPD.

CONCLUSIONS

Airway wall thickening and emphysema make independent contributions to airflow obstruction in COPD. These phenotypes show independent aggregation within families of individuals with COPD, suggesting that different genetic factors influence these disease processes.

Adverse childhood experiences and chronic obstructive pulmonary disease in adults

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an important cause of morbidity and mortality in the U.S. However, little is known about the influence of childhood stressors on its occurrence.

METHODS

Data were from 15,472 adult HMO members enrolled in the Adverse Childhood Experiences (ACE) Study from 1995 to 1997 and eligible for the prospective phase. Eight ACEs were assessed: abuse (emotional, physical, sexual); witnessing domestic violence; growing up with substance-abusing, mentally ill, or criminal household members; and parental separation or divorce. The number of ACEs (ACE Score) was used to examine the relationship of childhood stressors to the risk of COPD. Three methods of case ascertainment were used to define COPD: baseline reports of prevalent COPD, incident hospitalizations with COPD as a discharge diagnosis, and rates of prescription medications to treat COPD during follow-up. Follow-up data were available through 2004.

RESULTS

The ACE Score had a graded relationship to each of three measures of the occurrence of COPD. Compared to people with an ACE Score of 0, those with an ACE Score of > or =5 had 2.6 times the risk of prevalent COPD, 2.0 times the risk of incident hospitalizations, and 1.6 times the rates of prescriptions (p<0.01 for all comparisons). These associations were only modestly reduced by adjustment for smoking. The mean age at hospitalization decreased as the ACE Score increased (p<0.01).

CONCLUSIONS

Decades after they occur, adverse childhood experiences increase the risk of COPD. Because this increased risk is only partially mediated by cigarette smoking, other mechanisms by which ACEs may contribute to the occurrence of COPD merit consideration.

COPD in Asia: where East meets West

COPD is a global health concern, and is a major cause of chronic morbidity and mortality worldwide. According to the World Health Organization, it is currently the sixth leading cause of death in the world, and further increases in the prevalence and mortality of the disease is predicted for the coming decades. These increases are mainly linked to the epidemic of tobacco exposure and indoor and outdoor air pollution in Asian countries. The burden of COPD in Asia is currently greater than that in developed Western countries, both in terms of the total number of deaths and the burden of disease, as measured in years of life lost and years spent living with disability. The types of health-care policies and the practice of medicine vary considerably among the regions of Asia and have an impact on the burden of disease. Treatment aims in Asian countries are based on evidence-based management guidelines. Barriers to the implementation of disease management guidelines are related to issues of resource conflict and lack of organizational support rather than cultural differences in medical practice. To reduce this burden of COPD in Asian countries, there is a need for a multifaceted approach in improving awareness of prevalence and disease burden, in facilitating accurate diagnosis of COPD among chronic respiratory diseases, in championing health policies that reduce the burden of the main risk factors for COPD and in the wider use of evidence-based management for COPD.

The association of transforming growth factor beta 1 gene polymorphisms with the emphysema phenotype of COPD in Japanese

OBJECTIVE

The transforming growth factor beta-1 gene (TGFB1) is one of the most promising candidate genes for chronic obstructive pulmonary disease (COPD). Several case-control studies have been performed and generated inconsistent results. The possible reasons for these discrepancies include the diversity of ethnic populations and the heterogeneity of COPD, including emphysema and airway disease. We designed this study to investigate the association of single nucleotide polymorphisms (SNPs) of TGFB1 with the emphysema phenotype in the Japanese population.

METHODS

Eight SNPs in TGFB1 (rs2241712, rs1982072, and rs1800469 in the promoter region; rs1982073 in exon 1; rs2241716 and rs4803455 in intron 2; rs6957 and rs2241718 in the 3' region) were genotyped by allelic discrimination assays in 70 COPD patients with emphysema phenotype and 99 healthy smokers. The emphysema phenotype was identified by high-resolution computed tomography imaging using Goddard's method.

RESULTS

The frequency of one significant haplotype structured by the eight SNPs was significantly higher in the emphysema group (10%) than in the healthy smokers (4%, p=0.02). In the emphysema group, the predicted value of forced expiratory volume in 1 second after bronchodilator administration was significantly associated with the minor alleles of the two SNPs (rs1800469 and rs1982073, p=0.007 and 0.032, respectively), however, the low attenuation area and carbon monoxide diffusing capacity were not associated with the SNPs. In addition, the rs1800469T and rs1982073C alleles were significantly more prevalent in patients with severe and very severe airflow limitation than in those with mild and moderate airflow limitation (p=0.007 and 0.041, respectively).

CONCLUSIONS

One significant haplotype of TGFB1 is associated with the emphysema phenotype in the Japanese population. Two TGFB1 SNPs (rs1800469 and rs1982073) are associated with the severity of COPD in patients with emphysema phenotype.

Acute exacerbations of chronic bronchitis in elderly patients: pathogenesis, diagnosis and management

Chronic bronchitis (CB) is a disorder that is characterised by chronic mucus production. This disorder is called chronic obstructive pulmonary disease (COPD) when airflow obstruction is present. The majority of patients with COPD, which often goes undiagnosed or inadequately treated in the elderly, have symptoms consistent with CB. The clinical course of CB is usually punctuated by periodic acute exacerbations linked to infections caused by viral and typical or atypical bacterial pathogens. Acute exacerbations of chronic bronchitis (AECB) often lead to a decline in lung function and poor quality of life in association with increased risk of mortality and a significant economic impact on the healthcare system and society because of the direct costs of hospitalisations. In elderly individuals with COPD, co-morbidities play a vital role as determinants of health status and prognosis. Failure to eradicate infecting pathogens contributes to persistence of infection and inflammation that requires repeated courses of therapy and hospitalisation. Stratifying patients with AECB according to symptoms, degree of pulmonary function impairment and risk factors for poor outcome can help clinicians choose empirical antimicrobial chemotherapy regimens that are most likely to result in treatment success. Failure to cover likely pathogens associated with episodes of AECB can lead to lengthy hospital admissions and significant declines in functional status for elderly patients. Fluoroquinolones may provide the best therapeutic option for elderly patients with COPD who have complicated underlying CB but who are sufficiently stable to be treated in the outpatient setting. Optimised treatment for stable outpatients with CB may diminish the frequency of AECB, and effective antimicrobial therapy for AECB episodes can significantly diminish healthcare costs and maintain quality of life in the elderly patient.

Intronic single-nucleotide polymorphisms in Bcl-2 are associated with chronic obstructive pulmonary disease severity

BACKGROUND AND OBJECTIVE

COPD is a multifactorial disease influenced by genetic and environmental factors, and gene-by-environmental interactions. There is considerable variability in the degree of airflow obstruction, moreover only 10-15% of chronic smokers develop COPD. These observations indicate that additional risk factors, possibly genetic, contribute to not only the susceptibility to COPD but also the development and severity of COPD. Recent paradigms highlight the presence and causal role of apoptosis in emphysema. There is a large amount of information on the genes involved in the regulation of apoptosis and one of the most studied is Bcl-2. The aim of this study was to investigate the genetic association of Bcl-2 gene with the level of lung function, that is, the severity, of COPD.

METHODS

The genetic association of Bcl-2 polymorphisms with lung function was investigated in 261 Japanese patients with COPD using 12 single-nucleotide polymorphisms (SNPs) in Bcl-2.

RESULTS

Four SNPs showed a significant association between the high and low lung function groups in a dominant trait comparison. Subsequent linkage-disequilibrium mapping and analyses of haplotype structure also showed a significant association between the level of lung function and two haplotypes comprised of the associated SNPs in Bcl-2.

CONCLUSIONS

Although the linkage between Bcl-2 gene and the susceptibility to COPD remains to be clarified, the findings of the current study indicate that Bcl-2 might be influencing the level of lung function, that is, the development and severity of COPD.

[Alpha1-antitrypsin deficiency: situation in Spain and development of a screening program]

Studies undertaken in Spain indicate that 9% of the general population aged between 40 and 70 years is affected by chronic obstructive pulmonary disease (COPD). Although tobacco smoke is the causative factor in more than 90% of cases, it is estimated that only 10% to 20% of smokers develop COPD. This may be explained by the existence of genetic or environmental factors that modulate the toxic effects of tobacco. The best known genetic factor is alpha1-antitrypsin deficiency, which is associated with an increased risk of developing pulmonary emphysema in smokers. The most recent guidelines from both the World Health Organization and the American Thoracic Society/European Respiratory Society recommend the establishment of screening programs for the detection of alpha1-antitrypsin deficiency in patients with COPD. This strategy is crucial in Spain, where the disease is under diagnosed, mainly due to a low index of suspicion among doctors.

[Alpha1-antitrypsin deficiency: situation in Spain and development of a screening program]

Studies undertaken in Spain indicate that 9% of the general population aged between 40 and 70 years is affected by chronic obstructive pulmonary disease (COPD). Although tobacco smoke is the causative factor in more than 90% of cases, it is estimated that only 10% to 20% of smokers develop COPD. This may be explained by the existence of genetic or environmental factors that modulate the toxic effects of tobacco. The best known genetic factor is alpha1-antitrypsin deficiency, which is associated with an increased risk of developing pulmonary emphysema in smokers. The most recent guidelines from both the World Health Organization and the American Thoracic Society/European Respiratory Society recommend the establishment of screening programs for the detection of alpha1-antitrypsin deficiency in patients with COPD. This strategy is crucial in Spain, where the disease is under diagnosed, mainly due to a low index of suspicion among doctors.

Laboratory markers for COPD in “susceptible” smokers

Smoking is the major risk factor for the development of chronic obstructive pulmonary disease. Apart from the important preventive steps of smoking cessation, there are no other specific treatments for COPD that are as effective in reversing the condition. However, only a relatively small proportion of smokers-about 15%-will develop clinically relevant COPD. Allergy, airway hyper-responsiveness (AHR) to methacholine, and gender differences have been proposed to identify individuals susceptible to the development of COPD. However, variable response to cigarette smoke clearly suggests genetic susceptibility. Among the COPD candidate genes are those (a) that effect the production of proteases and antiproteases, (b) modulate the metabolism of toxic substances in cigarette smoke, (c) are involved with mucocilliary clearance, and (d) that influence inflammatory mediators. Recently, sputum cells from smokers with and without COPD were tested for Microsatellite DNA Instability (MSI) with positive results. This finding suggests that MSI can be a useful marker of genetic susceptibility and thereby indicate destabilization of the genome in the "susceptible" smoker. Nevertheless, COPD lacks established viable biomarkers to predict and monitor disease progression and outcome variables. Such monitoring tools may be induced sputum, exhaled air condensate, peripheral blood, urine, bronchial biopsies, and bronchoalveolar lavage fluid (BALF). This review summarizes recent research on potential laboratory markers in smokers and subsequent COPD development.

Prevalence of chronic obstructive pulmonary disease in Japanese people on medical check-up

In Japan, spirometry has not been included as an item in medical check-ups for all persons. The purpose of this study was to show evidence to recommend spirometry routinely on medical check-up for the early detection of chronic obstructive pulmonary disease (COPD). There were 12,760 enrolled persons who underwent medical check-up. COPD was defined as a ratio of forced expiratory volume in one second to slow vital capacity of 70% or less. We investigated the prevalence and its characteristics of COPD in people on medical check-up. The prevalence of COPD was 3.6% in all subjects, 4.5% in males, and 1.8% in females. In the comparison between males and females, the prevalence of COPD in males of most age groups was higher than that of females, and this difference was greater with aging. Males in their 50s and over 60 years old and females over 60 years old showed remarkably high prevalences. Occupations associated with a high smoking rate such as transportation-related occupations showed a higher prevalence of COPD. These results suggest that spirometry for all persons in medical check-ups can identify many COPD patients not aware of this disease. Spirometry should be carried out routinely on medical check-up.

Perfil radiológico do candidato ideal à cirurgia redutora de volume pulmonar no enfisema: uma revisão sistemática

INTRODUÇÃO: A cirurgia redutora de volume pulmonar é uma alternativa terapêutica para o enfisema pulmonar avançado. A avaliação radiológica do tipo e distribuição do enfisema parece ser o principal critério de indicação cirúrgica, além da função pulmonar. OBJETIVO: Determinar o nível de evidência científica referente ao padrão radiológico do candidato ideal à cirurgia redutora de volume pulmonar. MÉTODO: Revisão sistemática da literatura entre janeiro de 1994 e janeiro de 2004, utilizando as bases de dados: MEDLINE, EMbase, LILACS, The Cochrane Library e EBM Reviews. RESULTADOS: Foram identificados 208 artigos e 16 deles preenchiam os critérios do estudo. Destes, dois eram randomizados (um multicêntrico, denominado National Emphysema Treatment Trial, envolvendo 1.218 pacientes; e outro que, embora randomizado, com apenas 30 pacientes). Os 14 remanescentes eram estudos observacionais. O National Emphysema Treatment Trial identificou um subgrupo de pacientes de prognóstico favorável, quando submetidos à cirurgia redutora de volume pulmonar, formado por portadores de enfisema pulmonar avançado e heterogêneo, com predomínio nos lobos superiores, na presença de hiperdistensão pulmonar difusa e baixa capacidade para exercícios físicos. O padrão dos resultados dos demais estudos foi consistente na análise individual, apesar de sua heterogeneidade. Benefício cirúrgico, taxas de mortalidade e qualidade de vida também foram mensurados nos estudos observacionais. CONCLUSÃO: O perfil radiológico caracterizado pelo tipo de enfisema, sua heterogeneidade, distribuição e presença de hiperdistensão difusa, ao lado do nível de gravidade, representa o principal fator preditor de bom resultado cirúrgico. Esta recomendação tem o nível de evidência B, pela escassez de trabalhos na literatura.

Association analysis of tissue inhibitor of metalloproteinase2 gene polymorphisms with COPD in Egyptians

Proteinase/antiproteinase imbalance is recognized to play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). A relative increase in the activities of matrix metalloproteinases might be caused by mutations of tissue inhibitor of metalloproteinase2 (TIMP2). Recently, two polymorphisms of the TIMP2 gene, +853 G/A and -418 G/C (+551 and -720 from the translation initiation site), have been shown to be associated with the development of COPD in the Japanese population. In this study, a case-control association analysis for these polymorphisms was conducted in the Egyptian population using 106 COPD patients and 72 healthy controls. The genotype frequency of +853 G/A was significantly different between the patient and the control groups (P = 0.029), although no significant difference was detected in the allele frequency between the two groups. These results suggest that the +853 G/A polymorphism of the TIMP2 gene might be associated with COPD across ethnicities. In contrast, neither the distributions of genotype nor allele frequencies of -418 G/C were significantly different between the two groups, raising the possibility that a combination of different genetic factors contributes to the development of COPD in different ethnic groups.

The Role of Oxidative Stress in the Pathogenesis??of COPD

Chronic inflammation and oxidative stress are important features in the pathogenesis of COPD. The increased oxidative stress in patients with COPD is the result of an increased burden of inhaled oxidants, as well as increased amounts of reactive oxygen species (ROS) generated by various inflammatory, immune and epithelial cells of the airways. Oxidative stress has important implications on several events of lung physiology and for the pathogenesis of COPD. These include oxidative inactivation of antiproteases and surfactants, mucus hypersecretion, membrane lipid peroxidation, mitochondrial respiration, alveolar epithelial injury, remodeling of extracellular matrix, and apoptosis. An increased level of ROS produced in the airways is reflected by increased markers of oxidative stress in the airspaces, sputum, breath, lungs, and blood in patients with COPD. The biomarkers of oxidative stress such as H2O2, F2-isoprostanes, malondialdehyde and 4-hydroxy-2-nonenal have been successfully measured in breath condensate. ROS and aldehydes play a key role in enhancing the inflammation through the activation of mitogen-activated protein kinases and redox-sensitive transcription factors such as nuclear factor kappa B and activator protein-1. Oxidative stress also alters nuclear histone acetylation and deacetylation leading to increased gene expression of pro-inflammatory mediators in the lung. Oxidative stress may play a role in the poor clinical efficacy of corticosteroids in the treatment of COPD. Since a variety of oxidants, free radicals, and aldehydes are implicated in the pathogenesis of COPD it is likely that a combination of antioxidants may be effective in the treatment of COPD. Antioxidant compounds may also be of therapeutic value in monitoring oxidative biomarkers indicating disease progression. Various approaches to enhance the lung antioxidant screen and the clinical effectiveness of antioxidant compounds in the treatment of COPD are discussed.

Influence of family history and smoking habits on the incidence of self-reported physician's diagnosis of COPD

BACKGROUND

The incidence of chronic obstructive pulmonary disease (COPD) is little investigated. This study assessed the incidence of a self-reported physician's diagnosis of chronic bronchitis and/or emphysema (CBE) and/or COPD (CBE/COPD), and investigated the effects of a family history of CBE in 1992 and change in smoking habits (assessed in 1992 and 2000) on this incidence.

METHODS

A follow-up study in 2000 of 4933 subjects who responded to a respiratory questionnaire study in 1992 was performed. Response rate was 86.8%. Odds ratios (ORs) for incident cases of CBE/COPD were calculated by multiple Logistic regression.

RESULTS

The cumulative incidence of a physician's diagnosis of CBE/COPD was 2.9%. A family history of CBE predicted incident cases of CBE/COPD, OR 2.7 (95% CI 1.5-5.1). Also continuous smoking, relapse into smoking, or having stopped smoking between 1992 and 2000 had elevated ORs for incident cases of CBE/COPD, 2.6 (1.4-4.7), 7.2 (2.7-18.7), and 2.6 (1.3-5.3), while the OR for ex-smoking in 1992 as well as 2000 was 0.9 (0.4-1.8).

CONCLUSIONS

A family history of CBE increases the risk for development of CBE/COPD. Sustained smoking cessation over many years may be required to significantly reduce the risk of developing CBE/COPD.

Calorie-related rapid onset of alveolar loss, regeneration, and changes in mouse lung gene expression

Calorie restriction, followed by ad libitum refeeding, results, respectively, in loss and regeneration of pulmonary alveoli. We now show 35% of alveoli are lost within 72 h of onset of calorie restriction (⅔ decreased daily chow intake), and an additional 12% of alveoli are lost over a subsequent 12 days of calorie restriction. Tissue necrosis was not seen. Within 72 h of refeeding, after 15 days of calorie restriction, the number of alveoli returns to precalorie restriction values. Microarray lung gene profiling, in conjunction with Western and RNase protection assay, demonstrate an increase of granzyme and caspase gene expression 2–3 h after onset of calorie restriction. By 12 h, granzyme and caspase expression is no longer increased, but tumor necrosis factor death receptor expression is elevated. At 336 h, Fas death receptor expression is increased. Because granzymes are found only in cytotoxic lymphocytes (CTLs) and natural killer (NK) cells, we suggest calorie restriction activates these cells, initiating a series of molecular events that results in alveolar destruction. The evidence of involvement of CTLs and NK cells and the absence of necrosis are similar to alveolar destruction in chronic obstructive pulmonary disease.

Sex Differences in COPD and Lung Cancer Mortality Trends—United States, 1968–1999

PURPOSE

Cigarette smoking by U.S. women in the 1940s and 1950s caused large increases in smoking-related lung disease among women. To determine the magnitude of these increases, we compared the mortality trends for males and females in the United States for chronic obstructive pulmonary disease (COPD) and lung cancer for 1968-1999.

METHODS

We used the national mortality data files compiled by the National Center for Health Statistics of the CDC and U.S. census data to calculate age-adjusted (2000) death rates for COPD, lung cancer, and all causes.

RESULTS

COPD death rate for females increased by 382% from 1968 through 1999, whereas for males it increased by 27% during the same period. As a result, the COPD death rate for U.S. females is approaching that for males. The lung cancer death rate for females increased by 266% from 1968 to 1999, whereas for males, it increased by 15%.

CONCLUSIONS

Physicians, women, and groups interested in women's health issues need to be aware of these trends and target prevention strategies toward females.

Lack of association of group specific component haplotypes with lung function in smokers

BACKGROUND

Airway inflammation may affect the decrease in lung function that occurs in response to cigarette smoke, and is an important pathological feature in chronic obstructive pulmonary disease (COPD). Group specific component (GC) can act as an inflammatory mediator and may therefore have important influences on the inflammatory reaction in the airway. Several reports have described associations between GC haplotypes and COPD but these remain controversial. In addition, most of these studies were based on a small number of subjects.

METHODS

We have studied the contribution of GC haplotypes to the level of lung function in a large cohort of smokers with high or low lung function (mean FEV(1) % predicted 91.8 and 62.6, respectively). The frequency of the three major GC haplotypes (1S, 1F and 2) was investigated in 537 individuals with high lung function and 533 with low lung function.

RESULTS

No significant difference was found in the frequency of any GC haplotype between the high and low lung function groups. There was also no significant difference between the groups in genotype frequency of the two single nucleotide polymorphisms that underlie the haplotypes.

CONCLUSION

The GC haplotype does not contribute to reduced lung function in this cohort of smokers.

Vascular endothelial growth factor and the risk of smoking-related COPD

STUDY OBJECTIVES

Vascular endothelial growth factor (VEGF) signaling may be required for maintenance of the alveolar structures, and alveolar septal cell apoptosis could contribute to the pathogenesis of COPD presenting emphysematous changes; however, the common mutation at position 936 in the 3' untranslated region of the VEGF gene, a C to T substitution (the C allele was denoted as 1, and the T allele as 2), VEGF936*2, has been reported to be associated with significantly lower VEGF plasma levels. Based on these concepts, we hypothesized that VEGF936*1/2 polymorphism may be linked to the development of COPD.

DESIGN

The differences in VEGF936*1/2 allele frequency were examined in 113 patients with smoking-related COPD and two control groups (101 smoker/ex-smoker control subjects and 102 population control subjects) using the polymerase chain reaction-restriction fragment length polymorphism technique.

RESULTS

VEGF936*1/2 allele frequencies did not differ among the groups: 0.792/0.208 in COPD patients, 0.822/0.178 in smoker/ex-smoker control subjects, and 0.842/0.152 in population control subjects.

CONCLUSION

The 936 C/T polymorphism of the VEGF gene (including both homozygous and heterozygous) was not associated with the development of COPD (odds ratio, 1.23; 95% confidence interval, 0.760 to 1.995).

Effect of cigarette smoke on fibroblast-mediated gel contraction is dependent on cell density

Cigarette smoke exposure has been associated with a variety of diseases, including emphysema. The current study evaluated the interaction of cell density and cigarette smoke extract (CSE) on fibroblast contraction of collagen gels. Protein levels of transforming growth factor (TGF)-beta1, fibronectin, PGE(2), and TGF-beta1 mRNA were quantified. Although both 5 and 10% CSE inhibited contraction by low-density fibroblasts (1 x 10(5) cell/ml), only 5% CSE augmented contraction in higher-density cultures (3-5 x 10(5) cells/ml). CSE also inhibited fibronectin and TGF-beta1 production in low-density cultures but stimulated fibronectin production in high-density cultures. Active TGF-beta1 was readily detectable only in higher-density cultures and was markedly augmented by 5% CSE. In contrast, although TGF-beta1 mRNA expression was inhibited in high-density cultures by 10% CSE, expression was increased in the presence of 5% CSE. These results suggest that CSE-induced inhibition of low-density fibroblast contraction is due to inhibition of fibronectin production, whereas CSE's stimulatory effect on high-density cells is the result of increased release of TGF-beta1. These effects may help explain the varied pathologies associated with exposure to cigarette smoke.