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Objectives

The aim of this study was to identify the gene expression pattern specific in alveolar epithelial type II cells (ATII cells) isolated from patients with chronic obstructive pulmonary disease (COPD).

Design

Case control.

Setting

Two hospitals in Japan.

Participants

Three patients without COPD and three patients with COPD in microarray analyses. Five smokers without COPD and nine smokers with COPD in the following analyses.

Primary and secondary outcome measured

Primary outcome included identification of differentially expressed genes and activated or inhibited pathways in ATII cells of the patients with COPD, compared to those of the patients without COPD, using Affymetrix gene expression arrays. Secondary outcome included validation of the results of microarray analyses by quantitative reverse transcription-PCR.

Results

We isolated ATII cells from COPD and non-COPD lungs using fluorescence-activated cell sorting. We performed Affymetrix gene expression arrays on both types of ATII cells. Gene set enrichment analyses revealed that two major gene sets were enriched in ATII cells from COPD lungs: interferon-responsive gene sets and gene sets associated with cell cycle progression. Gene ontology term enrichment analyses indicated that among the interferon-stimulated genes, ATII cells in COPD expressed genes such as PSMB8, PSMB9, TAP1 and TAP2 associated with the antigen processing and presentation pathway. We validated the results of the microarray analyses using quantitative reverse transcriptase-PCR. In addition, FACS analysis indicated that the percentage of ATII cells to CD45-negative lung cells isolated from COPD lungs were significantly increased more than that from non-COPD lungs.

Conclusions

Our study demonstrated that interferon-stimulated genes involved in the antigen processing and presentation pathway and genes involved in cell cycle progression were enriched in ATII cells of the patients with COPD. These pathways might alter phenotypes of ATII cells in COPD lungs.

Chronic obstructive pulmonary disease (COPD) is a major global health problem. The etiology of COPD has been associated with apoptosis, oxidative stress, and inflammation. However, understanding of the molecular interactions that modulate COPD pathogenesis remains only partly resolved. We conducted an exploratory study on COPD etiology to identify the key molecular participants. We used information-theoretic algorithms including Context Likelihood of Relatedness (CLR), Algorithm for the Reconstruction of Accurate Cellular Networks (ARACNE), and Inferelator. We captured direct functional associations among genes, given a compendium of gene expression profiles of human lung epithelial cells. A set of genes differentially expressed in COPD, as reported in a previous study were superposed with the resulting transcriptional regulatory networks. After factoring in the properties of the networks, an established COPD susceptibility locus and domain-domain interactions involving protein products of genes in the generated networks, several molecular candidates were predicted to be involved in the etiology of COPD. These include COL4A3, CFLAR, GULP1, PDCD1, CASP10, PAX3, BOK, HSPD1, PITX2, and PML. Furthermore, T-box (TBX) genes and cyclin-dependent kinase inhibitor 2A (CDKN2A), which are in a direct transcriptional regulatory relationship, emerged as preeminent participants in the etiology of COPD by means of senescence. Contrary to observations in neoplasms, our study reveals that the expression of genes and proteins in the lung samples from patients with COPD indicate an increased tendency towards cellular senescence. The expression of the anti-senescence mediators TBX transcription factors, chromatin modifiers histone deacetylases, and sirtuins was suppressed; while the expression of TBX-regulated cellular senescence markers such as CDKN2A, CDKN1A, and CAV1 was elevated in the peripheral lung tissue samples from patients with COPD. The critical balance between senescence and anti-senescence factors is disrupted towards senescence in COPD lungs.

Author Summary

Chronic obstructive pulmonary disease or COPD is among the most lethal of respiratory diseases. While this disease has been well characterized, more studies are needed to learn the interaction of macromolecules involved in the progression towards illness. We explored possible interactions involved in the disease process using a compendium of gene expression data from frontline cells of the respiratory airways of the lung. The gene expression data were generated under a variety of experimental conditions. Application of computational schemes, which robustly detect enduring patterns, among sections of the genes represented across the varying experimental perturbations, revealed important regulatory relationships. When gene expression data from lungs of patients with COPD were factored into these networks of regulatory relationships, certain highly connected nodes (hubs) representing differentially expressed genes emerged. Notably included are members of the T-box (TBX) family of genes and CDKN2A, which regulate cellular aging. These findings were confirmed in studies using lung samples from COPD patients. Novel genes linked to TBX and CDKN2A include COL4A3, CFLAR, GULP1, PDCD1, CASP10, PAX3, BOK, HSPD1, PITX2, and PML, which were thus predicted to be involved in the disease process. The balance between senescence and anti-senescence factors is disrupted towards senescence in COPD lungs.

Although cigarette smoking is the major cause of chronic obstructive pulmonary disease (COPD), only a subset of smokers develops this disease. There is significant clinical, radiographic, and pathologic heterogeneity within smokers who develop COPD that likely reflects multiple molecular mechanisms of disease. It is possible that variations in the individual response to cigarette smoking form the basis for the distinct clinical and molecular phenotypes and variable natural history associated with COPD. Using the biologic premise of a molecular field of airway injury created by cigarette smoking, this response to tobacco exposure can be measured by molecular profiling of the airway epithelium. Noninvasive study of this field effect by profiling airway gene expression in patients with COPD holds important implications for our understanding of disease heterogeneity, early disease detection, and identification of novel disease-modifying therapies.

While the role cigarette smoke plays in chronic obstructive pulmonary disease (COPD) is undisputed, the molecular mechanisms by which inhaled smoke contributes to disease pathogenesis remains unclear. One of the major barriers to effective approaches to diagnose and manage COPD is the remarkable heterogeneity displayed by patients with the disease. Whole-genome gene-expression studies of airway and lung tissue from patients with COPD provide an opportunity to gain insights into disease pathogenesis, allowing for both a molecular understanding of the pathogenic processes that contribute to this heterogeneity, and the ability to target therapies to these processes. This review focuses on synthesizing and integrating the limited numbers of high-throughput gene expression studies that have been conducted on lung tissue and airway samples from smokers with COPD. Comparing several lung tissue studies using computational approaches, we find that the results suggest fundamental similarities and identify common biological processes underlying COPD, despite each study having identified largely nonoverlapping lists of differentially expressed genes. Given these similarities, we argue that additional lung tissue and airway gene-expression studies are warranted, and present a roadmap for how such studies could lead to clinically relevant tools that would impact COPD management.

Chronic obstructive pulmonary disease (COPD) is a major global health problem and is predicted to become the third most common cause of death by 2020. 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, and therefore there is a need to understand the pathophysiological mechanisms that could lead to new therapeutic strategies. The development of experimental models will help to dissect these mechanisms at the cellular and molecular level. COPD is a disease characterized by progressive airflow obstruction of the peripheral airways, associated with lung inflammation, emphysema and mucus hypersecretion. Different approaches to mimic COPD have been developed but are limited in comparison to models of allergic asthma. COPD models usually do not mimic the major features of human COPD and are commonly based on the induction of COPD-like lesions in the lungs and airways using noxious inhalants such as tobacco smoke, nitrogen dioxide, or sulfur dioxide. Depending on the duration and intensity of exposure, these noxious stimuli induce signs of chronic inflammation and airway remodelling. Emphysema can be achieved by combining such exposure with instillation of tissue-degrading enzymes. Other approaches are based on genetically-targeted mice which develop COPD-like lesions with emphysema, and such mice provide deep insights into pathophysiological mechanisms. Future approaches should aim to mimic irreversible airflow obstruction, associated with cough and sputum production, with the possibility of inducing exacerbations.

Rationale: Chromosome 12p has been linked to chronic obstructive pulmonary disease (COPD) in the Boston Early-Onset COPD Study (BEOCOPD), but a susceptibility gene in that region has not been identified.

Objectives: We used high-density single-nucleotide polymorphism (SNP) mapping to implicate a COPD susceptibility gene and an animal model to determine the potential role of SOX5 in lung development and COPD.

Methods: On chromosome 12p, we genotyped 1,387 SNPs in 386 COPD cases from the National Emphysema Treatment Trial and 424 control smokers from the Normative Aging Study. SNPs with significant associations were then tested in the BEOCOPD study and the International COPD Genetics Network. Based on the human results, we assessed histology and gene expression in the lungs of Sox5−/− mice.

Measurements and Main Results: In the case-control analysis, 27 SNPs were significant at P ≤ 0.01. The most significant SNP in the BEOCOPD replication was rs11046966 (National Emphysema Treatment Trial–Normative Aging Study P = 6.0 × 10−4, BEOCOPD P = 1.5 × 10−5, combined P = 1.7 × 10−7), located 3′ to the gene SOX5. Association with rs11046966 was not replicated in the International COPD Genetics Network. Sox5−/− mice showed abnormal lung development, with a delay in maturation before the saccular stage, as early as E16.5. Lung pathology in Sox5−/− lungs was associated with a decrease in fibronectin expression, an extracellular matrix component critical for branching morphogenesis.

Conclusions: Genetic variation in the transcription factor SOX5 is associated with COPD susceptibility. A mouse model suggests that the effect may be due, in part, to its effects on lung development and/or repair processes.

Background

The first changes associated with smoking are in the small airway epithelium (SAE). Given that smoking alters SAE gene expression, but only a fraction of smokers develop chronic obstructive pulmonary disease (COPD), we hypothesized that assessment of SAE genome-wide gene expression would permit biologic phenotyping of the smoking response, and that a subset of healthy smokers would have a “COPD-like” SAE transcriptome.

Methodology/Principal Findings

SAE (10th–12th generation) was obtained via bronchoscopy of healthy nonsmokers, healthy smokers and COPD smokers and microarray analysis was used to identify differentially expressed genes. Individual responsiveness to smoking was quantified with an index representing the % of smoking-responsive genes abnormally expressed (ISAE), with healthy smokers grouped into “high” and “low” responders based on the proportion of smoking-responsive genes up- or down-regulated in each smoker. Smokers demonstrated significant variability in SAE transcriptome with ISAE ranging from 2.9 to 51.5%. While the SAE transcriptome of “low” responder healthy smokers differed from both “high” responders and smokers with COPD, the transcriptome of the “high” responder healthy smokers was indistinguishable from COPD smokers.

Conclusion/Significance

The SAE transcriptome can be used to classify clinically healthy smokers into subgroups with lesser and greater responses to cigarette smoking, even though these subgroups are indistinguishable by clinical criteria. This identifies a group of smokers with a “COPD-like” SAE transcriptome.

Rationale: Oxidative stress is a key contributor in chronic obstructive pulmonary disease (COPD) pathogenesis caused by cigarette smoking. NRF2, a redox-sensitive transcription factor, dissociates from its inhibitor, KEAP1, to induce antioxidant expression that inhibits oxidative stress.

Objectives: To determine the link between severity of COPD, oxidative stress, and NRF2-dependent antioxidant levels in the peripheral lung tissue of patients with COPD.

Methods: We assessed the expression of NRF2, NRF2-dependent antioxidants, regulators of NRF2 activity, and oxidative damage in non-COPD (smokers and former smokers) and smoker COPD lungs (mild and advanced). Cigarette smoke–exposed human lung epithelial cells (Beas2B) and mice were used to understand the mechanisms.

Measurements and Main Results: When compared with non-COPD lungs, the COPD patient lungs showed (1) marked decline in NRF2-dependent antioxidants and glutathione levels, (2) increased oxidative stress markers, (3) significant decrease in NRF2 protein with no change in NRF2 mRNA levels, and (4) similar KEAP1 but significantly decreased DJ-1 levels (a protein that stabilizes NRF2 protein by impairing KEAP1-dependent proteasomal degradation of NRF2). Exposure of Bea2B cells to cigarette smoke caused oxidative modification and enhanced proteasomal degradation of DJ-1 protein. Disruption of DJ-1 in mouse lungs, mouse embryonic fibroblasts, and Beas2B cells lowered NRF2 protein stability and impaired antioxidant induction in response to cigarette smoke. Interestingly, targeting KEAP1 by siRNA or the small-molecule activator sulforaphane restored induction of NRF2-dependent antioxidants in DJ-1–disrupted cells in response to cigarette smoke.

Conclusions: NRF2-dependent antioxidants and DJ-1 expression was negatively associated with severity of COPD. Therapy directed toward enhancing NRF2-regulated antioxidants may be a novel strategy for attenuating the effects of oxidative stress in the pathogenesis of COPD.

One hundred million deaths were caused by tobacco in the 20th century, and it is estimated that there will be up to one billion deaths attributed to tobacco use in the 21st century. Chronic obstructive pulmonary disease (COPD) is rapidly becoming a global public health crisis with smoking being recognized as its most important causative factor. The most effective available treatment for COPD is smoking cessation. There is mounting evidence that the rate of progression of COPD can be reduced when patients at risk of developing the disease stop smoking, while lifelong smokers have a 50% probability of developing COPD during their lifetime. More significantly, there is also evidence that the risk of developing COPD falls by about half with smoking cessation. Several pharmacological interventions now exist to aid smokers in cessation; these include nicotine replacement therapy, bupropion, and varenicline. All pharmacotherapies for smoking cessation are more efficacious than placebo, with odds ratios of about 2. Pharmacologic therapy should be combined with nonpharmacologic (behavioral) therapy. Unfortunately, despite the documented efficacy of these agents, the absolute number of patients who are abstinent from smoking at 12 months of follow-up is low.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death throughout the world and is largely associated with cigarette smoking. Despite the appreciation of the central role of smoking in the development of COPD, only a relatively small number of smokers (15%–20%) develop COPD. Recent studies depicting familial aggregation suggest that some subjects may have a genetic predisposition to developing COPD. In this respect, a number of single nucleotide polymorphisms have been reported in association with different COPD features (subphenotypes), although much of this data remains controversial. Classical genetic studies (including twin and family studies) assume an “equal-environment” scenario, but as gene-environment interactions occur in COPD, this assumption needs revision. Thus, new integrated models are needed to examine the major environmental factors associated with COPD which include smoking as well as air pollution, and respiratory infections, and not only genetic predisposition. Revisiting this area, may help answer the question of what has more bearing in the pathogenesis of COPD—the environment or the genomic sequence of the affected subjects. It is anticipated that an improved understanding of this interaction will both enable improved identification of individuals susceptible to developing this disease, as well as improved future treatments for this disease.

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.

Chronic obstructive pulmonary disease (COPD) is a major public health problem with increasing prevalence worldwide. The primary aim of this study was to identify genes and gene ontologies associated with COPD severity. Gene expression profiling was performed on total RNA extracted from lung tissue of 18 former smokers with COPD. Class comparison analysis on mild (n = 9, FEV1 80–110% predicted) and moderate (n = 9, FEV1 50–60% predicted) COPD patients identified 46 differentially expressed genes (p<0.01), of which 14 genes were technically confirmed by quantitative real-time-PCR. Biological replication in an independent test set of 58 lung samples confirmed the altered expression of ten genes with increasing COPD severity, with eight of these genes (NNMT, THBS1, HLA-DPB1, IGHD, ETS2, ELF1, PTGDS and CYRBD1) being differentially expressed by greater than 1.8 fold between mild and moderate COPD, identifying these as candidate determinants of COPD severity. These genes belonged to ontologies potentially implicated in COPD including angiogenesis, cell migration, proliferation and apoptosis. Our secondary aim was to identify gene ontologies common to airway obstruction, indicated by impaired FEV1 and KCO. Using gene ontology enrichment analysis we have identified relevant biological and molecular processes including regulation of cell-matrix adhesion, leukocyte activation, cell and substrate adhesion, cell adhesion, angiogenesis, cell activation that are enriched among genes involved in airflow obstruction. Exploring the functional significance of these genes and their gene ontologies will provide clues to molecular changes involved in severity of COPD, which could be developed as targets for therapy or biomarkers for early diagnosis.

Introduction

Chronic obstructive pulmonary disease (COPD) is a leading cause of disability and death. The most common cause of COPD is smoking. There is evidence suggesting that genetic factors influence COPD susceptibility and variants in several candidate genes have been significantly associated with COPD. In this study, we aimed to investigate the possible association of the TNF-α –308, SPB+1580, IL-13 –1055 gene polymorphisms and latent adenovirus C infection with COPD in an Egyptian population.

Material and methods

Our study included 115 subjects (75 smokers with COPD, 25 resistant smokers and 15 non-smokers) who were subjected to spirometric measurements, identification of adenovirus C and genotyping of TNF-α –308G/A, SP-B+1580 C/T and IL-13 –1055 C/T polymorphisms by real-time PCR.

Results

The adenovirus C gene was identified in all subjects. The distribution of TNF-α genotypes showed no significant differences between different groups. However, homozygous A genotype was associated with a significant decrease in FEV1, FEV1/FVC and FEF25/75% of predicted in COPD (p < 0.05). As regards SP-B genotypes, resistant smokers had a significantly higher homozygous T genotype frequency compared to COPD and non smokers (p = 0.005). Interleukin 13 genotypes showed no significant difference between different groups. There was a significant decrease in FEF25/75% of predicted in T allele carriers in COPD patients (p = 0.001).

Conclusions

The COPD is a disease caused by the interaction of combined genes and environmental influences, in the presence of smoking and latent adenovirus C infection, TNF-α –308A, SPB +1580 T and IL-13 –1055 T polymorphisms predispose to the development of COPD.

Background

Oxidative stress plays a potential role in the pathogenesis and progression of chronic obstructive pulmonary disease (COPD). Glutathione S-transferases (GSTs) detoxify toxic compounds in tobacco smoke via glutathione-dependent mechanisms. Little is known about the regulation and expression of GSTs in COPD lung and their presence in airway secretions.

Methods

GST alpha, pi and mu were investigated by immunohistochemistry in 72 lung tissue specimens and by Western analysis in total lung homogenates and induced sputum supernatants from non-smokers, smokers and patients with variable stages of COPD severity.

Results

GST alpha was expressed mainly in the airway epithelium. The percentage of GST alpha positive epithelial cells was lower in the central airways of patients with very severe (Stage IV) COPD compared to mild/moderate COPD (p = 0.02). GST alpha by Western analysis was higher in the total lung homogenates in mild/moderate COPD compared to cases of very severe disease (p < 0.001). GST pi was present in airway and alveolar epithelium as well as in alveolar macrophages. GST mu was expressed mainly in the epithelium. Both GST alpha and pi were detectable in sputum supernatants especially in patients with COPD.

Conclusion

This study indicates the presence of GST alpha and pi especially in the epithelium and sputum supernatants in mild/moderate COPD and low expression of GST alpha in the epithelium in cases of very severe COPD. The presence of GSTs in the airway secretions points to their potential protective role both as intracellular and extracellular mediators in human lung.

Introduction

Chronic obstructive pulmonary disease (COPD) constitutes a worldwide health problem. There is currently an urgent and unmet need for the development of small molecule therapeutics capable of blocking and/or reversing the progression of the disorder. Recent studies have greatly illuminated our understanding of the multiple pathogenic processes associated with COPD. Of paramount importance is the key role played by proteases, oxidative stress, apoptosis, and inflammation. Insights gained from these studies have made possible the exploration of new therapeutic approaches.

Areas covered

An overview of major developments in COPD research with emphasis on low molecular weight neutrophil elastase inhibitors is described in this review.

Expert opinion

Great strides have been made toward our understanding of the biochemical and cellular events associated with COPD. However, our knowledge regarding the inter-relationships among the multiple pathogenic mechanisms and their mediators involved is till limited. The problem is further compounded by the unavailability of suitable validated biomarkers for assessing the efficacy of potential therapeutic interventions. The complexity of COPD suggests that effective therapeutic interventions may require the administration of more than one agent such as, for instance, an HNE or MMP-12 inhibitor with an anti-inflammatory agent such as a phosphodiesterase-4 inhibitor, or a dual function agent capable of disrupting the cycle of proteolysis, apoptosis, inflammation and oxidative stress

Background

Genetic factors play a role in chronic obstructive pulmonary disease (COPD) but are poorly understood. A number of candidate genes have been proposed on the basis of the pathogenesis of COPD. These include the matrix metalloproteinase (MMP) genes which play a role in tissue remodelling and fit in with the protease - antiprotease imbalance theory for the cause of COPD. Previous genetic studies of MMPs in COPD have had inadequate coverage of the genes, and have reported conflicting associations of both single nucleotide polymorphisms (SNPs) and SNP haplotypes, plausibly due to under-powered studies.

Methods

To address these issues we genotyped 26 SNPs, providing comprehensive coverage of reported SNP variation, in MMPs- 1, 9 and 12 from 977 COPD patients and 876 non-diseased smokers of European descent and evaluated their association with disease singly and in haplotype combinations. We used logistic regression to adjust for age, gender, centre and smoking history.

Results

Haplotypes of two SNPs in MMP-12 (rs652438 and rs2276109), showed an association with severe/very severe disease, corresponding to GOLD Stages III and IV.

Conclusions

Those with the common A-A haplotype for these two SNPs were at greater risk of developing severe/very severe disease (p = 0.0039) while possession of the minor G variants at either SNP locus had a protective effect (adjusted odds ratio of 0.76; 95% CI 0.61 - 0.94). The A-A haplotype was also associated with significantly lower predicted FEV1 (42.62% versus 44.79%; p = 0.0129). This implicates haplotypes of MMP-12 as modifiers of disease severity.

Chronic obstructive pulmonary disease (COPD) is the most common chronic respiratory condition in adults and is characterized by progressive airflow limitation that is not fully reversible. The main etiological agents linked with COPD are cigarette smoking and biomass exposure but respiratory infection is believed to play a major role in the pathogenesis of both stable COPD and in acute exacerbations. Acute exacerbations are associated with more rapid decline in lung function and impaired quality of life and are the major causes of morbidity and mortality in COPD. Preventing exacerbations is a major therapeutic goal but currently available treatments for exacerbations are not very effective. Historically, bacteria were considered the main infective cause of exacerbations but with the development of new diagnostic techniques, respiratory viruses are also frequently detected in COPD exacerbations. This article aims to provide a state-of-the art review of current knowledge regarding the role of infection in COPD, highlight the areas of ongoing debate and controversy, and outline emerging technologies and therapies that will influence future diagnostic and therapeutic pathways in COPD.

Chronic obstructive pulmonary disease (COPD) and asthma represent a substantial portion of primary care practice. In adults, differentiating asthma from COPD can be difficult but is important because of the marked differences in treatment, disease progression, and outcomes between the 2 conditions. Currently, clinical COPD is often misdiagnosed or undiagnosed until late in the disease. Earlier diagnosis could markedly reduce morbidity and improve quality of life. Establishing a diagnosis of COPD requires spirometry testing, interpreted in the context of the patient's symptoms, smoking status, age, and comorbidities. Additional tests and tools may be helpful in the differential diagnosis, including questionnaires specifically developed to discriminate between COPD and asthma and, in special cases, imaging studies. Follow-up and monitoring of asthma and COPD are always necessary and provide additional benefit in patients in whom only continued care and reassessment can confirm the final diagnosis, such as younger individuals with fixed airway obstruction, smokers with asthma, and patients with both disorders. Key areas for improvement include enhanced case identification, improved quality and interpretation of findings on spirometry, and increased use of tools such as differential diagnosis questionnaires and algorithms to guide the diagnostic and monitoring process. To achieve optimal outcomes, the primary care team should make every effort to establish a firm diagnosis. For this review, we conducted a PubMed search with no time limits using the Medical Subject Headings chronic obstructive pulmonary disease or COPD and asthma, in association with the following search terms: diagnosis, differential diagnosis, mixed or comorbid disease, diagnostic techniques, spirometry, questionnaires, and primary care.

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and morbidity globally, and its development is mainly associated with tobacco/biomass smoke-induced oxidative stress. Hence, targeting systemic and local oxidative stress with agents that can balance the antioxidant/redox system can be expected to be useful in the treatment of COPD. Preclinical and clinical trials have revealed that antioxidants/redox modulators can detoxify free radicals and oxidants, control expression of redox and glutathione biosynthesis genes, chromatin remodeling and inflammatory gene expression; and are especially useful in preventing COPD exacerbations. In this review, various novel approaches and problems associated with these approaches in COPD are reviewed.

On-going airway inflammation is characteristic for the pathophysiology of chronic obstructive pulmonary disease (COPD). However, the key factors determining the decrease in lung function, an important clinical parameter of COPD, are not clear. Genome-wide linkage analyses provide evidence for significant linkage to airway obstruction susceptibility loci on chromosome 8p23, the location of the human defensin gene cluster. Moreover, a genetic variation in the defensin beta 1 (DEFB1) gene was found to be associated with COPD. Therefore, we hypothesized that DEFB1 is differently regulated and expressed in human lungs during COPD progression. Gene expression of DEFB1 was assessed in bronchial epithelium and BAL fluid cells of healthy controls and patients with COPD and using bisulfite sequencing and ChIP analysis, the epigenetic control of DEFB1 mRNA expression was investigated. We can demonstrate that DEFB1 mRNA expression was significantly increased in bronchopulmonary specimen of patients with COPD (n = 34) vs. healthy controls (n = 10) (p<0.0001). Furthermore, a significant correlation could be detected between DEFB1 and functional parameters such as FEV1 (p = 0.0024) and the FEV1/VC ratio (p = 0.0005). Upregulation of DEFB1 mRNA was paralleled by changes in HDAC1-3, HDAC5 and HDAC8 mRNA expression. Whereas bisulfite sequencing revealed no differences in the methylation state of DEFB1 promoter between patients with COPD and controls, ChIP analysis showed that enhanced DEFB1 mRNA expression was associated with the establishment of an active histone code. Thus, expression of human DEFB1 is upregulated and related to the decrease in pulmonary function in patients with COPD.

Background

The new Global Obstructive Lung Disease (GOLD) guidelines advice to focus treatment in Chronic Obstructive Pulmonary Disease (COPD) on improvement of functional state, prevention of disease progression and minimization of symptoms. So far no validated questionnaires are available to measure symptom and functional state in daily clinical practice. The aim of this study was to develop and validate the Clinical COPD Questionnaire (CCQ).

Methods

Qualitative research with patients and clinicians was performed to generate possible items to evaluate clinical COPD control. Thereafter, an item reduction questionnaire was sent to 77 international experts. Sixty-seven experts responded and the 10 most important items, divided into 3 domains (symptoms, functional and mental state) were included in the CCQ (scale: 0 = best, 6 = worst).

Results

Cross-sectional data were collected from 119 subjects (57 COPD, GOLD stage I-III; 18 GOLD stage 0 and 44 (ex)smokers). Cronbach's α was high (0.91). The CCQ scores in patients (GOLD 0-III) were significantly higher than in healthy (ex)smokers. Furthermore, significant correlations were found between the CCQ total score and domains of the SF-36 (ρ = 0.48 to ρ = 0.69) and the SGRQ (ρ = 0.67 to ρ = 0.72). In patients with COPD, the correlation between the CCQ and FEV1%pred was ρ =-0.49. Test-retest reliability was determined in 20 subjects in a 2-week interval (Intra Class Coefficient = 0.94). Thirty-six smokers with and without COPD showed significant improvement in the CCQ after 2 months smoking cessation, indicating the responsiveness of the CCQ.

Conclusion

The CCQ is a self-administered questionnaire specially developed to measure clinical control in patients with COPD. Data support the validity, reliability and responsiveness of this short and easy to administer questionnaire.

Since the discovery of alpha-1 antitrypsin in the early 1960s, several new genes have been suggested to play a role in chronic obstructive pulmonary disease (COPD) pathogenesis. Yet, in spite of those advances, much about the genetic basis of COPD still remains to be discovered. Unbiased approaches, such as genome-wide association (GWA) studies, are critical to identify genes and pathways and to verify suggested genetic variants. Indeed, most of our current understanding about COPD candidate genes originates from GWA studies. Experiments in form of cross-study replications and advanced meta-analyses have propelled the field towards unravelling details about COPD's pathogenesis. Here, we review the discovery of genetic variants in association with COPD phenotypes by discussing the available approaches and current findings. Limitations of current studies are considered and future directions provided.

Background

Inflammation, both local and systemic, is a hallmark of chronic obstructive pulmonary disease (COPD). Inflammatory mediators such as TNFα and GM-CSF are secreted by lung epithelium, alveolar macrophages and other inflammatory cells and are thought to be important contributors in the pathogenesis of COPD. Indeed, neutrophils are activated by these cytokines and these cells are one of the major inflammatory cell types recruited to the pulmonary compartment of COPD patients. Furthermore, these inflammatory mediators are found in the peripheral blood of COPD patients and, therefore, we hypothesized that TNFα/GM-CSF-induced protein profiles can be found in peripheral neutrophils of COPD patients.

Methods

Using fluorescence 2-dimensional difference gel electrophoresis we investigated differentially regulated proteins in peripheral neutrophils from COPD patients and healthy age-matched control subjects. Furthermore, protein profiles from COPD patients were compared with those of neutrophils of healthy age-matched controls that were stimulated with TNFα and/or GM-CSF in vitro. Protein gels were compared using DeCyder 7.0 software.

Results

We identified 7 significantly regulated protein spots between peripheral neutrophils from COPD patients and age-matched healthy control subjects. Stimulation of peripheral neutrophils with TNFα, GM-CSF or TNFα + GM-CSF in vitro resulted in 13, 20 and 22 regulated protein spots, respectively. However, these cytokine-induced protein differences did not correspond with the protein differences found in neutrophils from COPD patients.

Conclusion

These results show that neutrophils from COPD patients have a unique protein profile compared to neutrophils from healthy age-matched controls. Furthermore, the neutrophil profiles of COPD patients do not reflect putative dominant signals induced by TNFα, GM-CSF or their combination. Our results indicate that systemic neutrophil responses in COPD patients are caused by a unique but subtle interplay between multiple inflammatory signals.

COPD is underdiagnosed and its early assessment is problematic. It has been suggested that symptomatic smokers with normal FEV1/FVC (Stage 0 COPD, GOLD criteria) can develop COPD in the future. Potential early biomarkers in COPD include the matrix metallo-proteinases (MMPs). It is not yet known, whether alterations in MMP expression are associated with smoking alone or with the risk of developing COPD. In this cross-sectional study MMP-8, MMP-9 and MMP-12 were determined from induced sputum and plasma by ELISA, immunocytochemistry, zymography, and/or Western blot in non-smokers (n = 32), smokers with symptoms (Stage 0, GOLD criteria) (n = 23) or without symptoms (n = 23). Only MMP-8 differentiated Stage 0 COPD from non-symptomatic smokers (p = 0.02). MMP-9 levels were significantly elevated in the induced sputum of non-symptomatic smokers and Stage 0 COPD (p = 0.01, p < 0.001) compared to non-smokers, but did not differ between the two subgroups of smokers. MMP-12 was higher only at Stage 0 compared to non-smokers (p = 0.04). MMP-8, MMP-9 and MMP-12 immunoreactivity was localized in macrophages and neutrophils, especially in smokers. MMP-8 levels correlated significantly with the small airway flow parameters (MEF50, MEF25) (p = 0.005 and p = 0.0004) and markers of neutrophil activation (myeloperoxidase, lactoferrin). In conclusion MMP-8 may differentiate Stage 0 from healthy smokers.

Chronic obstructive pulmonary disease (COPD) results in major remodeling of the distal airspaces and changes in the differentiation profile of the airway epithelium. The cellular and molecular mechanisms involved in initiation and progression of this disease are little understood. Although environmental factors, including cigarette smoke, have been directly implicated in the pathogenesis of COPD, genetic risk factors also appear to play a fundamental role in the individual's susceptibility to this disease. Lung development depends on precise coordination of signals, such as fibroblast growth factors (Fgf), Sonic Hedgehog (Shh), retinoic acid, Notch, and Tgf β. Dramatic changes in the pattern of branching and differentiation of the lung epithelium results from disruption of these signals in genetically altered mice. Recent studies, including whole-genome expression and genome-wide association analyses, suggest that some molecular regulators originally described in developmental processes may be altered in patients with COPD. Whether disturbances in the molecular and cellular events mediated by these genes during development participate in the initiation or exacerbation of COPD, needs further investigation. The role of selected pathways, including Sonic hedgehog, Notch, retinoid, and Tgf β in the developing lung and the potential association with COPD are discussed.