Genetics and pulmonary medicine. 9. Molecular genetics of chronic obstructive pulmonary disease

Trends in the prevalence and incidence of chronic obstructive pulmonary disease among adults aged ≥50 years in the United States, 2000-2020

Background

Understanding the trends of the prevalence and incidence rate of chronic obstructive pulmonary disease (COPD) is vital for improving the control and prevention of COPD. We aimed to examine the trends in the prevalence and incidence rate of COPD among adults aged 50 years or older in the United States during 2000-2020.

Methods

Utilizing data from the Health and Retirement Study, we analyzed COPD prevalence across survey waves and calculated COPD incidence rates between consecutive interview waves, stratified by gender and race. We employed joinpoint regression models to investigate trends in COPD prevalence and incidence.

Results

The individuals reporting COPD are more likely to be women and Caucasians. The age-adjusted prevalence of COPD among adults aged 50 years and over showed an increasing trend throughout the study period, spanning from 9.02% in 2000 to 9.88% in 2020 (average biennial percent change [ABPC] = 0.41, 95% confidence interval [CI]: 0.10, 0.71; p = 0.01). The age-adjusted incidence rate of COPD among adults aged 50 and over showed a decreasing trend throughout the study period 1031.1 per 100,000 person-years in 2000 to 700.5 per 100,000 person-years in 2020 (ABPC = -1.63, 95% CI: -2.88, -0.36; p = 0.02).

Conclusion

Our findings indicate a rising prevalence of COPD among older adults in the United States since 2000, while the incidence rate of COPD has shown a declining trend.

p53- and PAI-1-mediated induction of C-X-C chemokines and CXCR2: importance in pulmonary inflammation due to cigarette smoke exposure

We previously demonstrated that tumor suppressor protein p53 augments plasminogen activator inhibitor-1 (PAI-1) expression in alveolar epithelial cells (AECs) during chronic cigarette smoke (CS) exposure-induced lung injury. Chronic lung inflammation with elevated p53 and PAI-1 expression in AECs and increased susceptibility to and exacerbation of respiratory infections are all associated with chronic obstructive pulmonary disease (COPD). We recently demonstrated that preventing p53 from binding to the endogenous PAI-1 mRNA in AECs by either suppressing p53 expression or blockading p53 interactions with the PAI-1 mRNA mitigates apoptosis and lung injury. Within this context, we now show increased expression of the C-X-C chemokines (CXCL1 and CXCL2) and their receptor CXCR2, and the intercellular cellular adhesion molecule-1 (ICAM-1), in the lung tissues of patients with COPD. We also found a similar increase in lung tissues and AECs from wild-type (WT) mice exposed to passive CS for 20 wk and in primary AECs treated with CS extract in vitro. Interestingly, passive CS exposure of mice lacking either p53 or PAI-1 expression resisted an increase in CXCL1, CXCL2, CXCR2, and ICAM-1. Furthermore, inhibition of p53-mediated induction of PAI-1 expression by treatment of WT mice exposed to passive CS with caveolin-1 scaffolding domain peptide reduced CXCL1, CXCL2, and CXCR2 levels and lung inflammation. Our study reveals that p53-mediated induction of PAI-1 expression due to chronic CS exposure exacerbates lung inflammation through elaboration of CXCL1, CXCL2, and CXCR2. We further provide evidence that targeting this pathway mitigates lung injury associated with chronic CS exposure.

Leukocyte Mitochondrial DNA Copy Number Is Associated with Chronic Obstructive Pulmonary Disease

BACKGROUND

Oxidative stress is known to be involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). Evidence suggests that leukocytes mitochondria DNA (mtDNA) is susceptible to undergo mutations, insertions, or depletion in response to reactive oxidative stress (ROS). We hypothesize that mtDNA copy number is associated with the development of COPD.

METHODOLOGY/PRINCIPAL FINDINGS

Relative mtDNA copy number was measured by a quantitative real-time PCR assay using DNA extracted from peripheral leukocytes. MtDNA copy number of peripheral leukocytes in the COPD group (n = 86) is significantly decreased compared with non-smoker group (n = 77) (250.3± 21.5 VS. 464.2± 49.9, P<0.001). MtDNA copy number in the COPD group was less than that in the healthy smoking group, but P value nearly achieved significance (250.3± 21.5 VS. 404.0± 76.7, P = 0.08) MtDNA copy number has no significance with age, gender, body mass index, current smoking, and pack-years in COPD group, healthy smoker group and no smoker group, respectively. Serum glutathione level in the COPD group is significantly decreased compared with healthy smoker and non-smoker groups (4.5± 1.3 VS. 6.2± 1.9 and 4.5± 1.3 VS. 7.1±1.1 mU/mL; P<0.001 respectively). Pearson correlation test shows a significant liner correlation between mtDNA copy number and serum glutathione level (R = 0.2, P = 0.009).

CONCLUSIONS/SIGNIFICANCE

COPD is associated with decreased leukocyte mtDNA copy number and serum glutathione. COPD is a regulatory disorder of leukocytes mitochondria. However, further studies are needed to determine the real mechanisms about the gene and the function of mitochondria.

Chronic obstructive pulmonary disease (COPD) assessment test scores corresponding to modified Medical Research Council grades among COPD patients

BACKGROUND/AIMS

In assigning patients with chronic obstructive pulmonary disease (COPD) to subgroups according to the updated guidelines of the Global Initiative for Chronic Obstructive Lung Disease, discrepancies have been noted between the COPD assessment test (CAT) criteria and modified Medical Research Council (mMRC) criteria. We investigated the determinants of symptom and risk groups and sought to identify a better CAT criterion.

METHODS

This retrospective study included COPD patients seen between June 20, 2012, and December 5, 2012. The CAT score that can accurately predict an mMRC grade ≥ 2 versus < 2 was evaluated by comparing the area under the receiver operating curve (AUROC) and by classification and regression tree (CART) analysis.

RESULTS

Among 428 COPD patients, the percentages of patients classified into subgroups A, B, C, and D were 24.5%, 47.2%, 4.2%, and 24.1% based on CAT criteria and 49.3%, 22.4%, 8.9%, and 19.4% based on mMRC criteria, respectively. More than 90% of the patients who met the mMRC criteria for the 'more symptoms group' also met the CAT criteria. AUROC and CART analyses suggested that a CAT score ≥ 15 predicted an mMRC grade ≥ 2 more accurately than the current CAT score criterion. During follow-up, patients with CAT scores of 10 to 14 did not have a different risk of exacerbation versus those with CAT scores < 10, but they did have a lower exacerbation risk compared to those with CAT scores of 15 to 19.

CONCLUSIONS

A CAT score ≥ 15 is a better indicator for the 'more symptoms group' in the management of COPD patients.

Estimating the time interval between exposure to the World Trade Center disaster and incident diagnoses of obstructive airway disease

Respiratory disorders are associated with occupational and environmental exposures. The latency period between exposure and disease onset remains uncertain. The World Trade Center (WTC) disaster presents a unique opportunity to describe the latency period for obstructive airway disease (OAD) diagnoses. This prospective cohort study of New York City firefighters compared the timing and incidence of physician-diagnosed OAD relative to WTC exposure. Exposure was categorized by WTC arrival time as high (on the morning of September 11, 2001), moderate (after noon on September 11, 2001, or on September 12, 2001), or low (during September 13–24, 2001). We modeled relative rates and 95% confidence intervals of OAD incidence by exposure over the first 5 years after September 11, 2001, estimating the times of change in the relative rate with change point models. We observed a change point at 15 months after September 11, 2001. Before 15 months, the relative rate for the high- versus low-exposure group was 3.96 (95% confidence interval: 2.51, 6.26) and thereafter, it was 1.76 (95% confidence interval: 1.26, 2.46). Incident OAD was associated with WTC exposure for at least 5 years after September 11, 2001. There were higher rates of new-onset OAD among the high-exposure group during the first 15 months and, to a lesser extent, throughout follow-up. This difference in relative rate by exposure occurred despite full and free access to health care for all WTC-exposed firefighters, demonstrating the persistence of WTC-associated OAD risk.

Role of glutathione S transferase polymorphism in COPD with special reference to peoples living in the vicinity of the open cast coal mine of Assam

BACKGROUND

COPD may develop due to variation in the functioning of antioxidants along with smoking and environmental factors in genetically susceptible individuals. Since there are different views about the antioxidants responsible for detoxifying xenobiotic compound in the human body whose functional variation may lead to obstructive disease, this associative study has been taken up between GST gene polymorphism and COPD in populations exposed to coal dusts.

METHODS

Genotypes of the 70 COPD patients and 85 non COPD patients were determined by PCR based methods followed by multiplex PCR of GSTT1 and GSTM1 genes taking albumin gene as a control. Suspended particulate analyses were determined through the Respirable Dust sampler along with the FTIR analysis of the dust samples from the glass microfiber filters.

RESULTS

Dust sampling analysis reveals higher level of respirable suspended particulate matter, non respirable particulate matter, SO2 and NO2 present in air of the study site. FTIR analysis also suggests a higher concentration of organic silicone and aliphatic C-F compounds present in air of the study site and when spirometry was done, low lung function was observed among most of the subjects. GSTM1 null type was significantly associated with low lung function in smoker groups and the presence of at least one active allele (either GSTM1/GSTT1) seemed to have a protective role in the development of COPD.

CONCLUSIONS

GSTM1 (null genotype) appeared to be a risk factor for lower lung function in smokers living in the vicinity of coal mines. Apart from polluted environment and genetic susceptibility, mixed coal dust exposure rich in organic silicone and aliphatic C-F compounds also appears to be a factor for the low lung function.

Therapeutic potential of growth factors in pulmonary emphysematous condition

Pulmonary emphysema is a major manifestation of chronic obstructive pulmonary disease (COPD), which is characterized by progressive destruction of alveolar parenchyma with persistent inflammation of the small airways. Such destruction in the distal respiratory tract is irreversible and irreparable. All-trans-retinoic acid was suggested as a novel therapy for regeneration of lost alveoli in emphysema. However, profound discrepancies were evident between studies. At present, no effective therapeutic options are available that allow for the regeneration of lost alveoli in emphysematous human lungs. Recently, some reports on rodent's models have suggested the beneficial effects of various growth factors toward alveolar maintenance and repair processes.

Airway disease: similarities and differences between asthma, COPD and bronchiectasis

Airway diseases are highly prevalent worldwide; however, the prevalence of these diseases is underestimated. Although these diseases present several common characteristics, they have different clinical outcomes. The differentiation between asthma, chronic obstructive pulmonary disease and bronchiectasis in the early stage of disease is extremely important for the adoption of appropriate therapeutic measures. However, because of the high prevalence of these diseases and the common pathophysiological pathways, some patients with different diseases may present with similar symptoms. The objective of this review is to highlight the similarities and differences between these diseases in terms of the risk factors, pathophysiology, symptoms, diagnosis and treatment.

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.

Ageing and smoking contribute to plasma surfactant proteins and protease imbalance with correlations to airway obstruction

BACKGROUND

A significant number of young people start smoking at an age of 13-15, which means that serious smoking-evoked changes may have been occurred by their twenties. Surfactant proteins (SP) and matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have been linked to cigarette smoke induced lung remodelling and chronic obstructive pulmonary disease (COPD). However, the level of these proteins has not been examined during ageing or in young individuals with short smoking histories.

METHODS

Plasma levels of SP-A, SP-D, MMP-9, and TIMP-1 were measured by EIA/ELISA from young (18-23 years) non-smoking controls (YNS) (n = 36), smokers (YS) (n = 51), middle aged/elderly (37-77 years) non-smoking controls (ONS) (n = 40), smokers (OS) (n = 64) (FEV1/FVC >0.7 in all subjects) and patients with COPD (n = 44, 35-79 years).

RESULTS

Plasma levels of SP-A increased with age and in the older group in relation to smoking and COPD. Plasma SP-D and MMP-9 levels did not change with age but were elevated in OS and COPD as compared to ONS. The TIMP-1 level declined with age but increased in chronic smokers when compared to ONS. The clearest correlations could be detected between plasma SP-A vs. age, pack years and FEV1/FVC. The receiver operating characteristic (ROC) curve analysis revealed SP-A to be the best marker for discriminating between patients with COPD and the controls (area under ROC curve of 0.842; 95% confidence interval, 0.785-0.899; p < 0.001).

CONCLUSIONS

Age has a significant contribution to potential markers related to smoking and COPD; SP-A seems to be the best factor in differentiating COPD from the controls.

Advances in proteomic techniques for biomarker discovery in COPD

Chronic obstructive pulmonary disease (COPD) is a disorder characterized by chronic inflammation of the lung with airflow obstruction and progressive deterioration of pulmonary function. The need to discover and validate biomarkers as prognostic tools of development and progression of the disease has received further support with the advent of proteomic techniques. Liquid chromatography-mass spectrometry (LC/MS) and gel electrophoresis-mass spectrometry (2-DE/MS) have been applied to investigate the proteome of a number of lung-origin samples, including sputum, bronchoalveolar lavage fluid, exhaled-breath condensate, cells and biopsies from COPD patients. In particular, 2-DE and MS are the main proteomic approaches with 2-DE presenting the major approach for quantitative proteomics. The molecules identified as potential biomarkers of COPD may represent a preliminary step for better comprehension of the mechanisms involved in the onset/progression of the disease.

Combined effects of IL-8 and CXCR2 gene polymorphisms on breast cancer susceptibility and aggressiveness

Background

Interleukin-8 (IL-8/CXCL-8) is a prototype of the ELR⁺CXC chemokines that play an important role in the promotion and progression of many human cancers including breast cancer. We have recently showed the implication of polymorphism (-251) T/A of IL-8 gene in the susceptibility and prognosis of breast carcinoma. IL-8 acts through its CXCR1 and CXCR2 receptors. CXCR2, expressed on the endothelial cells, is the receptor involved in mediating the angiogenic effects of ELR⁺CXC chemokines and in particular IL-8.

In the current study, we investigated the susceptibility and prognostic implications of the genetic variation in CXCR2 in breast carcinoma. We also confirmed the implication of IL-8 (-251) T/A polymorphism in a larger cohort. Finally, we combined the IL-8 and CXCR2 variant alleles and analyzed their effects in breast cancer risk and prognosis.

Methods

We used the allele-specific polymerase chain reaction to characterize the variation of IL-8 and CXCR2 for 409 unrelated Tunisian patients with breast carcinoma and 301 healthy control subjects. To estimate the relative risks, Odds ratios and 95% confidence intervals were calculated using unconditional logistic regression after adjusting for the known risk factors for breast cancer. Associations of the genetic marker with the rates of breast carcinoma-specific overall survival and disease-free survival were assessed using univariate and multivariate analyses.

Results

A highly significant association was found between the homozygous CXCR2 (+ 1208) TT genotype (adjusted OR = 2.89; P = 0.008) and breast carcinoma. A significantly increased risk of breast carcinoma was associated with IL-8 (-251) A allele (adjusted OR = 1.86; P = 0.001). The presence of two higher risk genotypes (the TA and TT in IL-8, and the TT in CXCR2) significantly increased the risk of developing breast carcinoma (adjusted OR = 4.15; P = 0.0004).

The CXCR2 (+ 1208) T allele manifested a significant association with an aggressive phenotype of breast carcinoma as defined by a large tumor size, a high histological grade, and auxiliary's lymph node metastasis. A significant association between the IL-8 (-251) A allele and the aggressive form of breast carcinoma was also found.

Moreover, the presence of the IL-8 (-251) A and/or the CXCR2 (+ 1208) T allele showed a significant association with a decreased overall survival and disease-free survival in breast carcinoma patients.

Conclusion

Our results indicated that the polymorphisms in IL-8 and CXCR2 genes are associated with increased breast cancer risk, as well as disease progress, supporting our hypothesis for IL-8 and ELR⁺CXC chemokine receptor (CXCR2) involvement in breast cancer pathogenesis.

Association of TLR4-T399I polymorphism with chronic obstructive pulmonary disease in smokers

Tobacco smoking has been considered the most important risk factor for chronic obstructive pulmonary disease (COPD) development. However, not all smokers develop COPD and other environmental and genetic susceptibility factors underlie disease pathogenesis. Recent studies have indicated that the impairment of TLR signaling might play a crucial role in the development of emphysema. For this purpose we investigated the prevalence and any possible associations of common TLR polymorphisms (TLR2-R753Q, TLR4-D299G, and TLR4-T399I) in a group of 240 heavy smokers (>20 pack years), without overt atherosclerosis disease, of whom 136 had developed COPD and 104 had not. The presence of TLR4-T399I polymorphism was associated with a 2.4-fold increased risk for COPD development (P = .044), but not with disease stage or frequency of exacerbations. Considering that infections contribute to COPD and emphysema pathogenesis, our findings possibly indicate that dysfunctional polymorphisms of innate immune genes can affect the development of COPD in smokers. Although this finding warrants further investigation, it highlights the importance of impaired innate immunity towards COPD development.

Glucocorticoid receptor gene polymorphisms and potential association to chronic obstructive pulmonary disease susceptibility and severity

OBJECTIVE

As chronic obstructive pulmonary disease (COPD) is known for poor glucocorticoid (GC) response, we hypothesized that polymorphic variants of the glucocorticoid receptor (GR) gene might predispose for COPD and/or disease severity.

MATERIAL AND METHODS

Three out of about 50 of the most abundant receptor GR gene polymorphisms were investigated in a case-control study which included 207 patients with chronic bronchitis or COPD (mean FEV1 50.5% predicted, GOLD I-IV) and 106 age matched healthy subjects (mean FEV1 101.8% predicted). These were genotyped: a) for the N363S (Exon 2; 1220 A > G (I)); b) the BCLI restriction fragment length polymorphism (Intron 2; 647 C >G (II)); and c) the ER2223EK (Exon 2; 198, 200 G >A (III)), using RT-PCR and PCR-RFLP method on genomic DNA isolated from EDTA blood.

RESULTS

Genotype distribution between COPD and healthy subjects were alike in all of these three polymorphisms. N363S was found in 0.94% of the healthy and 0% of the COPD subjects. BCLI was detected in 11.3% of the controls and 15.5% of the COPD patients whereas heterozygote frequency was less in the COPD (44.4%) group (controls 60.4%). ER2223EK lacks in any of the study subjects. Further, SNPs did not correlate with COPD severity stage (GOLD), exacerbation rates, and clinical course.

CONCLUSION

COPD is not linked to gene polymorphisms N363S, BCLI-RFLP, and ER2223EK. Since we analyzed only these 3 receptor gene polymorphisms, this study cannot rule out that other GR gene variants and linkages may be of influence.

Racial and sex differences in chronic obstructive pulmonary disease susceptibility, diagnosis, and treatment

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease (COPD) is an increasing cause of morbidity and mortality worldwide. Although COPD has historically been considered a disease of white male smokers, it now clearly impacts both sexes and all races, with mortality rising fastest in women and African-Americans. Given the scarcity of data about non-African-American minorities, this review will focus on the disparities in COPD susceptibility, diagnosis, and treatment between men and women and between African-Americans and whites.

RECENT FINDINGS

Although the changing epidemiology of COPD in part reflects the changing epidemiology of cigarette smoking, there are data suggesting that women and African-Americans may be particularly susceptible to tobacco smoke and that the diagnosis, treatment, and natural history of the disease are influenced by race and sex.

SUMMARY

The possibility that sex or race or both, may influence COPD susceptibility and progression is of critical importance, and may mean that the potential future impact of the disease has been underestimated. Unfortunately, our understanding of these differences and the efficacy of standard COPD treatments in women and minorities remains limited by the low enrollment in clinical trials.

Trachea epithelium as a "canary" for cigarette smoking-induced biologic phenotype of the small airway epithelium

The initial site of smoking-induced lung disease is the small airway epithelium, which is difficult and time consuming to sample by fiberoptic bronchoscopy. We developed a rapid, office-based procedure to obtain trachea epithelium without conscious sedation from healthy nonsmokers (n= 26) and healthy smokers (n= 19, 27 +/- 15 pack-year). Gene expression differences (fold change >1.5, p < 0.01, Benjamini-Hochberg correction) were assessed with Affymetrix microarrays. A total of 1,057 probe sets were differentially expressed in healthy smokers versus nonsmokers, representing >500 genes. Trachea gene expression was compared to an independent group of small airway epithelial samples (n= 23 healthy nonsmokers, n= 19 healthy smokers, 25 +/- 12 pack-year). The trachea epithelium is more sensitive to smoking, responding with threefold more differentially expressed genes than small airway epithelium. The trachea transcriptome paralleled the small airway epithelium, with 156 of 167 (93%) genes that are significantly up- and downregulated by smoking in the small airway epithelium showing similar direction and magnitude of response to smoking in the trachea. Trachea epithelium can be obtained without conscious sedation, representing a less invasive surrogate "canary" for smoking-induced changes in the small airway epithelium. This should prove useful in epidemiologic studies correlating gene expression with clinical outcome in assessing smoking-induced lung disease.

[Phenotypic heterogeneity of chronic obstructive pulmonary disease]

A functional definition of chronic obstructive pulmonary disease (COPD) based on airflow limitation has largely dominated the field. However, a view has emerged that COPD involves a complex array of cellular, organic, functional, and clinical events, with a growing interest in disentangling the phenotypic heterogeneity of COPD. The present review is based on the opinion of the authors, who have extensive research experience in several aspects of COPD. The starting assumption of the review is that current knowledge on the pathophysiology and clinical features of COPD allows us to classify phenotypic information in terms of the following dimensions: respiratory symptoms and health status, acute exacerbations, lung function, structural changes, local and systemic inflammation, and systemic effects. Twenty-six phenotypic traits were identified and assigned to one of the 6 dimensions. For each dimension, a summary is provided of the best evidence on the relationships among phenotypic traits, in particular among those corresponding to different dimensions, and on the relationship between these traits and relevant events in the natural history of COPD. The information has been organized graphically into a phenotypic matrix where each cell representing a pair of phenotypic traits is linked to relevant references. The information provided has the potential to increase our understanding of the heterogeneity of COPD phenotypes and help us plan future studies on aspects that are as yet unexplored.

Early response of gene clusters is associated with mouse lung resistance or sensitivity to cigarette smoke

We have investigated the effects of cigarette smoke exposure in three different strains of mice. DBA/2 and C57BL/6J are susceptible to smoke and develop different lung changes in response to chronic exposure, whereas ICR mice are resistant to smoke and do not develop emphysema. The present study was carried out to determine early changes in the gene expression profile of mice exposed to cigarette smoke with either a susceptible or resistant phenotype. The three strains of mice were exposed to smoke from three cigarettes per day, 5 days/wk, for 4 wk. Microarray analysis was carried out on total RNA extracted from the lung using the Affymetrix platform. Cigarette smoke modulates several clusters of genes (i.e., proemphysematous, acute phase response, and cell adhesion) in smoke-sensitive DBA/2 or C57BL/6J strains, but the same genes are not altered by smoke in ICR resistant mice. Only a few genes were commonly modulated by smoke in the three strains of mice. This pattern of gene expression suggests that the response to smoke is strain-dependent and may involve different molecular signaling pathways. Real-time quantitative PCR was used to verify the pattern of modulation of selected genes and their potential biological relevance. We conclude that gene expression response to smoke is highly dependent on the mouse genetic background. We speculate that the definition of gene clusters associated, to various degrees, with mouse susceptibility or resistance to smoke may be instrumental in defining the molecular basis of the individual response to smoke-induced lung injury in humans.

Air pollutants, oxidative stress and human health

Air pollutants have, and continue to be, major contributing factors to chronic diseases and mortality, subsequently impacting public health. Chronic diseases include: chronic obstructive pulmonary diseases (COPD), cardiovascular diseases (CVD), asthma, and cancer. Byproducts of oxidative stress found in air pollutants are common initiators or promoters of the damage produced in such chronic diseases. Such air pollutants include: ozone, sulfur oxides, carbon monoxide, nitrogen oxides, and particulate matter. Interaction between oxidative stress byproducts and certain genes within our population may modulate the expression of specific chronic diseases. In this brief review we attempt to provide some insight into what we currently know about the health problems associated with various air pollutants and their relationship in promoting chronic diseases through changes in oxidative stress and modulation of gene expression. Such insight eventually may direct the means for effective public health prevention and treatment of diseases associated with air pollution and treatment of diseases associated with air pollution.

Acute tobacco smoke-induced airways inflammation in spontaneously hypertensive rats

Common laboratory rats and mice fail to develop persistent, progressive pulmonary inflammation found in chronic obstructive pulmonary disease as a result of tobacco smoke exposure. We hypothesized that spontaneously hypertensive rats would be more susceptible than normal Wistar Kyoto rats to acute tobacco smoke-induced pulmonary inflammation due to impaired apoptosis. Spontaneously hypertensive rats display systemic oxidative stress, inflammation, hypercoagulation, and immunosupression, similar to humans with chronic obstructive pulmonary disease. Male spontaneously hypertensive rats and Wistar Kyoto rats were exposed whole-body to tobacco smoke (total particulate concentration 75-85 mg/m(3)) or filtered air for 6 h/day for 2 or 15 days (3 days/wk). Tobacco smoke caused an increase in bronchoalveolar lavage fluid neutrophils at both time points in each strain. Significantly more neutrophils were noted in spontaneously hypertensive rats at 15 days compared to Wistar Kyoto rats. There was a trend of increase for macrophages in spontaneously hypertensive rats at both time points (significant at 2 days). TUNEL assay detected apoptotic cells in bronchoalveolar lavage fluid and lung tissue sections. The number of apoptotic neutrophils in airway walls and bronchoalveolar lavage fluid increased at 2 days in both strains, but at 15 days the effect was much lower in spontaneously hypertensive rats than in Wistar Kyoto rats. Tobacco smoke induces a greater inflammatory response associated with lower apoptotic neutrophils in the lungs of spontaneously hypertensive rats compared to Wistar Kyoto rats. The spontaneously hypertensive rat may be a more relevant animal model of acute tobacco smoke-induced airway inflammation than other laboratory rats.

Model for estimating the population prevalence of chronic obstructive pulmonary disease: cross sectional data from the Health Survey for England

Background

Chronic obstructive pulmonary disease (COPD) is a major but neglected public health problem. Currently 1.4% of the England population has a clinical diagnosis of COPD, but the true burden of the disease has not been known with certainty, as many cases remain undiagnosed.

Methods

A mathematical model based on cross sectional data from a representative sample of the population in England (the Heath Survey for England 2001, n = 10,750) was developed allowing estimates on the prevalence of COPD (defined based on the presence of airflow obstruction) to be obtained. Logistic regression analysis was used to investigate and choose risk factors for inclusion in the model and to derive the prevalence estimates based on the strength of association between selected risk factors and the outcome COPD. The model allows the prevalence to be estimated in populations at national level and also at regional and large local areas, based on their compositions according to age, sex, smoking and ethnicity, and on area degrees of urbanisation and deprivation. We applied the model to measure the prevalence of COPD in England and in some sub-groups of the population within the country.

Results

The prevalence of COPD in England is estimated as 3.1% (3.9% in men and 2.4% in women) in the population over 15 years of age, and 5.3% (6.8% in men and 3.9% in women) in 45 year-olds and over. There was a 7-fold variation in the prevalence across subgroups of the population, with lowest values in Asian women from wealthy rural areas (1.7%), and highest in black men from deprived urban areas (12.5%).

Conclusion

The model can be used to estimate population prevalence of COPD from large general practices to national level, and as a tool to identify areas of high levels of unmet needs for COPD priority health actions. The results from the model highlight the importance of including variables other than age, sex and smoking, i.e. levels of deprivation, urbanisation and ethnicity, when estimating population prevalence of COPD. The model should be validated at local level and incorporated into case-finding strategies.

Angiotensin-converting-enzyme gene polymorphisms, smoking and chronic obstructive pulmonary disease

While tobacco smoking is the main risk factor for chronic obstructive pulmonary disease (COPD) only a fraction of smokers go on to develop the disease. We investigated the relationship between the insertion (I)--deletion (D) polymorphisms in the Angiotensin converting enzyme (ACE) gene and the risk of developing COPD in smokers by determining the distribution of the ACE genotypes (DD, ID and II) in 151 life-long male smokers. 74 of the smokers had developed COPD (62 +/- 2 years; FEV1 44 +/- 6% reference) whereas the rest retained normal lung function (56 +/- 2 yrs; FEV1 95 +/- 3% reference). In addition, we genotyped 159 males recruited randomly from the general population. The prevalence of the DD genotype was highest (p = 0.01) in the smokers that developed COPD and its presence was associated with a 2-fold increase in the risk for COPD (OR 2.2; IC95% 1.1 to 5.5). Surprisingly, the 151 individuals in the smoking population did not demonstrate Hardy-Weinberg equilibrium unlike the 159 recruited from the general population. Our results suggest that ACE polymorphisms are associated with both the smoking history of an individual and their risk of developing COPD.

COPD: racial disparities in susceptibility, treatment, and outcomes

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States and mortality continues to increase particularly among African Americans. Although this increase may be caused by changing smoking habits, some studies suggest that African Americans may be more susceptible to tobacco smoke than whites. Unlike other respiratory diseases for which there are significant published data on racial and ethnic disparities in disease outcomes, such information is notably lacking in the COPD literature. This article examines the available data concerning racial disparities in COPD susceptibility and care.

IL-8 (-251 A/T) and CXCR2 (+1208 C/T) gene polymorphisms and risk of multiple sclerosis in Iranian patients

IL-8 plays important roles in CNS development, modulation of neuronal survival and excitability. Among IL-8 receptors, only CXCR2 is known to be present in the brain. The ability of individuals in producing IL-8 is partially determined by IL-8 -251 A/T polymorphism. Therefore, the aim of the present study was to investigate the association between IL-8 -251 A/T and CXCR2 +1208 C/T gene polymorphisms and susceptibility to multiple sclerosis (MS). Two hundred and twenty-three MS patients and 319 healthy and ethnic matched controls were included in this study. IL-8 promoter (-251 A/T) and CXCR2 (+1208 C/T) gene polymorphisms were genotyped via allele specific PCR (AS-PCR) method. A significant difference was found in IL-8 -251 A/T polymorphism between MS patients and controls (p = 0.04). This deference was a result of a higher incidence of the low producer allele of IL-8 (T allele) in MS patients compared to controls. However, there was no significant association between different clinical findings (EDSS score, progression index, disease onset age, and the type of disease) and IL-8 -251 A/T polymorphism. Furthermore, no significant association existed between CXCR2 +1208 C/T polymorphism and MS susceptibility or different clinical parameters in patients. In summary, carriers of IL-8 -251 T allele may have increased susceptibility to MS because of their differences in neuron survival or increased chances of viral persistence compared to carriers of A allele.

Racial and gender differences in susceptibility to tobacco smoke among patients with chronic obstructive pulmonary disease

BACKGROUND

Although chronic obstructive pulmonary disease (COPD) has been considered a disease of Caucasian men, recent data show mortality rising faster among women and African-Americans. Some have suggested these groups are more susceptible to tobacco smoke. We examined this issue in our own population of COPD patients.

METHODS

Beginning in March 2003 we prospectively developed a COPD research database to facilitate recruitment for clinical trials. Enrollees are recruited from clinics and paid advertising and their demographics, medical/smoking histories, and spirometric data are recorded. We examined the smoking histories and pulmonary function of enrollees over 45, with 20 pack-years of smoking, FEV(1)/FVC (forced expiratory volume forced vital capacity) <0.70, and a race-adjusted post-bronchodilator FEV(1)<80%. The primary outcome was the loss of lung function per pack-year smoked, or Susceptibility Index (SI), calculated using the formula: (% predicted FEV(1)-100)/pack-years.

RESULTS

A total of 585 patients enrolled during the study period and 330 met our inclusion criteria. Caucasians were older than African-Americans (63 vs. 58, P=0.0003) and had more pack-years of smoking (57 vs. 43, P=0.0003). There were no differences in lung function or bronchodilator reversibility among the racial or gender subgroups. Caucasians had less loss of lung function per pack-year smoked than African-Americans (SI=-1.02% vs. -1.34%, P=0.007) and men less than women (SI=-0.98% vs. -1.21%, P=0.001). Caucasian males appeared relatively protected from tobacco smoke (SI=-0.93%), while African-American women appeared most susceptible (SI=-1.42%).

CONCLUSIONS

There are important differences in racial and gender susceptibility to tobacco smoke among patients with COPD. African-American females appear to be at highest risk and may benefit most from smoking cessation.

Should patients with acute exacerbation of chronic bronchitis be treated with antibiotics? Advantages of the use of fluoroquinolones

The pathological changes in chronic bronchitis (CB) produce airflow obstruction, reduce the effectiveness of the mucocilliary drainage system and lead to bacterial colonisation of bronchial secretion. The presence of bacteria induces an inflammatory response mediated by leukocytes. There is a direct relationship between the degree of impairment of the mucocilliary drainage system, the density of bacteria in mucus and the number of leukocytes in the sputum. Purulent sputum is a good marker of a high bacterial load. Eventually, if the number of leukocytes is high, their normal activity could decrease the effectiveness of the drainage system, increase the bronchial obstruction and probably damage the lung parenchyma. Whenever the density of bacteria in the bronchial lumen is >or=10(6) CFU/mL, there is a high probability that the degree of inflammatory response will lead to a vicious cycle which in turn tends to sustain the process. This situation can arise during the clinical course of any acute exacerbation of CB, independently of its aetiology, provided the episode is sufficiently severe and/or prolonged. Fluoroquinolones of the third and fourth generation are bactericidal against most microorganisms usually related to acute exacerbations of CB. Their diffusion to bronchial mucus is adequate. When used in short (5-day) treatment they reduce the bacterial load in a higher proportion than is achieved by beta-lactam or macrolide antibiotics given orally. Although the clinical cure rate is similar to that obtained with other antibiotics, the time between exacerbations could be increased.

Systemic Immunological Response to Exercise in Patients with Chronic Obstructive Pulmonary Disease: What Does It Mean?

Chronic obstructive pulmonary disease (COPD) is no longer seen as a pulmonary disease, but is increasingly associated with systemic effects with important clinical relevance. Systemic immunological changes in COPD patients are characterized by an increased number of circulating inflammatory cells, functional changes of the inflammatory cells, elevated plasma levels of cytokines, and oxidative stress. Physical exercise induces an abnormal systemic inflammatory and oxidative response in COPD patients, which is seen in both the circulation and the peripheral muscles. Although mechanisms and consequences of these effects are not yet fully understood, they could be harmful in COPD patients by inducing damage or functional changes in, for example, skeletal muscles. Whether these changes of the immune system can also affect the susceptibility to infections in these patients is unknown. The concept of COPD as a systemic rather than only a pulmonary disease also opens new perspectives on the development for new therapeutic interventions. The effects of new antioxidative and anti-inflammatory agents are investigated. A better understanding of the complexity of the systemic effects will aid the development of new therapies and management strategies for patients with COPD.

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.

Asthma and COPD: differences and similarities. With special reference to the usefulness of budesonide/formoterol in a single inhaler (Symbicort) in both diseases

Asthma and chronic obstructive pulmonary disease (COPD) both have a high prevalence worldwide and yet each condition remains underdiagnosed. Despite a number of common features, these inflammatory respiratory syndromes have distinct clinical outcomes. COPD represents a greater economic burden than asthma because it has a less favourable prognosis and is associated with greater morbidity and mortality. Therefore, it is important to distinguish between these two diseases at an early stage, so that appropriate therapy can be prescribed to prevent deterioration. However, effective treatments that may be used in both conditions can minimise the effects of misdiagnosis and maximise the impact of treatment without the associated complexity when both conditions occur together. The current review summarises the differences and similarities of asthma and COPD, in terms of risk factors, pathophysiology, symptoms and diagnosis, to provide greater understanding of the role of budesonide/formoterol in a single inhaler in both diseases.

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.

[New therapeutic approaches to COPD]

Classification of severity of the disease is the basis of the therapeutic concept for chronic obstructive lung disease (COPD). Besides pharmacological treatment, preventive measures and rehabilitation with training are the main parts of COPD therapy. Weaning patients of cigarette smoking is of utmost importance in every stage for the course of the disease. Inhalative short acting bronchodilators on demand are the basis of treatment in all stages as well as long acting bronchodilators from stage II on as continuous medication. Theophyllines are of additional importance in higher degrees of the disease. Inhalative steroids are indicated in severe stages III or higher, systemic steroids only during exacerbations as short course therapy. Oxygen long time treatment, intermittent non-invasive ventilation, and operations in some cases are additional therapies.

Alpha1-Antitrypsin as a Risk for Infant and Adult Respiratory Outcomes in a National Birth Cohort

Reduced alpha1-antitrypsin (AAT) encoded by the gene SERPINA1 is a potential risk for pulmonary disease. We investigated SERPINA1 polymorphism as a risk for infant and adult pulmonary morbidity, and adult respiratory function and its change between 43 and 53 yr. We used data on a British national representative sample (n = 5,362) studied since birth in 1946 to age 53 yr (when n = 3,035), when DNA was first obtained. SERPINA1 Z and, to a lesser extent, S carriers had an increased risk of infant lower respiratory infection compared with those who were neither S nor Z carriers (Z carriers: odds ratio = 2.32, 95% confidence interval = 1.37-3.92; S but not Z carriers odds ratio = 1.58, 95% confidence interval = 1.10-2.28) after adjustment for environmental, socioeconomic, and developmental factors, and breast-feeding. There was no difference in the adult outcomes at 53 yr according to genotype, nor was there any association of genotype with change in forced expiratory volume at 1 s between 43 and 53 yr. Lower alpha1-antitrypsin, as indicated by carrier status for the Z and S alleles, was a risk for infant lower respiratory infection, but not for adult respiratory outcomes.

ACE I allele and eNOS G allele crosstalk may have a role in chronic obstructive pulmonary disease

BACKGROUND

Pulmonary hypertension, a characteristic of chronic obstructive pulmonary disease (COPD) has led us to investigate polymorphisms in angiotensin-converting enzyme (ACE) and endothelial nitric oxide synthase (eNOS) genes.

DESIGN AND METHODS

Sixty-six normal and 27 patients, all of whom were smokers, were screened for ACE Insertion/Deletion (I/D) and eNOS G894T and CA-repeat polymorphisms and for plasma ACE and NO levels.

RESULTS

Elevated ACE and decreased NO levels were obtained with the pattern of II to ID to DD and GG to GT to TT conversion, respectively. Furthermore, the genotype combination of II and GG was significantly greater in controls as compared to patients (P = 0.01; OR = 2.43; 95% CI: 1.21-4.87; RR = 2.00, 1.15-3.48). The CA-repeat multialleles showed a trimodal pattern in both the groups with a frequency range of 0.0057-0.103 and 0.0208-0.1875 in the controls and patients, respectively.

CONCLUSIONS

The lower ACE and higher NO levels by virtue of the interchromosomal interaction between the I and G alleles appear to cause less vasoconstriction and increase vasodilatation that may be advantageous in the improvement of the disease.

alpha1-Antitrypsin deficiency . 6: new and emerging treatments for alpha1-antitrypsin deficiency

Alpha-1-antitrypsin (AAT) deficiency is a genetic condition that increases the risk of developing lung and liver disease, as well as other associated conditions. Most treatment of affected individuals is not specifically directed at AAT deficiency but focuses on the resultant disease state. The only currently available specific therapeutic agent-namely, intravenous augmentation with plasma derived AAT protein-is marketed in a limited number of countries. Treatments aimed at correcting the underlying genetic abnormality, supplementing or modifying the gene product, and halting or reversing organ injury are now beginning to emerge. These innovative approaches may prove effective at modifying or eliminating diseases association with AAT deficiency.

Prospects for new drugs for chronic obstructive pulmonary disease

No currently available treatments have been shown to slow the progression of chronic obstructive pulmonary disease (COPD) or suppress the inflammation in small airways and lung parenchyma. However, several new treatments are in clinical development; some target the inflammatory process and others are directed against structural cells. A group of specific therapies are directed against the influx of inflammatory cells into the airways and lung parenchyma that occurs in COPD; these include agents directed against adhesion molecules and chemokines, as well as therapies to oppose tumour necrosis factor alpha and increase interleukin 10. Broad-range anti-inflammatory drugs are now in phase III development for COPD; they include inhibitors of phosphodiesterase 4. Other drugs that inhibit cell signalling include inhibitors of p38 mitogen-activated protein kinase, nuclear factor kappaB, and phosphoinositide-3-kinase gamma. More specific approaches are to give antioxidants, inhibitors of inducible nitric oxide synthase, and antagonists of leukotriene B4 receptor. Inhibitors of epidermal-growth-factor-receptor kinase and calcium-activated chloride channels have the potential to prevent overproduction of mucus. Therapy to inhibit fibrosis is being developed against transforming growth factor beta1 and protease-activated receptor 2. There is also a search for inhibitors of serine proteinases and matrix metalloproteinases to prevent lung destruction and the development of emphysema, as well as drugs such as retinoids that might even reverse this process. Effective delivery of drugs to the sites of disease in the peripheral lung is an important consideration, and there is a need for validated biomarkers and monitoring techniques in early clinical studies with new therapies for COPD.

Real-time PCR-based genotyping assay for CXCR2 polymorphisms

BACKGROUND

The human chemokine receptor CXCR2 (IL8RB) is a high affinity receptor for interleukin-8 as well as other CXC chemokines, and is involved in the chemotaxis of immune cells. Genetic variants of CXCR2 have potential relevance in various inflammatory human disorders. We developed a real-time polymerase chain reaction (PCR)-based allelic discrimination assay for the detection of the CXCR2 single nucleotide polymorphisms (SNPs) C785T, T1208C and G1440A.

METHODS

Polymorphisms were delineated using PCR amplification of specific alleles (PASA). Allele-specific primers were developed for both wild-type and mutant alleles. An additional nucleotide mismatch at the third position from the 3' end of each primer was used to improve amplification specificity and to prevent generation of nonspecific products. Genotypes were assigned based on PCR growth curves and melt curve analysis performed on a SmartCycler using SYBR Green I chemistry.

RESULTS

Genotyping assignments were successfully performed in a set of 20 human DNA samples, and were validated by comparison with results from direct DNA sequencing and agarose gel electrophoresis of PCR products.

CONCLUSIONS

Due to its rapid and relatively inexpensive performance and accuracy, the presented allelic discrimination assay for CXCR2 polymorphisms has wide applicability, especially for high-throughput sample analysis in large population genotyping studies.

Targeting the issues in chronic obstructive lung disease

Chronic obstructive pulmonary disease (COPD) is a disease of unclear aetiology and variable pathology among patients. Little is known about the cellular mechanisms which cause this condition and, although the incidence of COPD has been rising worldwide for some time, research efforts have only very recently increased. Medication thus far has focused on symptom treatment rather than targeting identifiable disease mechanisms. Such treatment has consisted primarily of bronchodilators, both beta-agonists and anticholinergic in action. Treatment with steroids has been disappointing, except in the case of acute exacerbation, and this has shifted the research focus to characterising the inflammatory process in COPD as distinct from that in asthma. New targets for pharmacotherapy are coming to light as information is gained about specific inflammatory mediators active in COPD and the role of oxidative stress in this disease. In addition, new approaches include describing the role of exogenous antiproteases in restoring the balance between protease-antiprotease mechanisms that may be defective in this disease. Ultimately, exploration of the molecular genetics of COPD will provide new targets for future pharmacological agents.