Chronic obstructive pulmonary disease. 1: Susceptibility factors for COPD the genotype-environment interaction

[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.

Association between polymorphisms of microsomal epoxide hydrolase and COPD: results from meta-analyses

BACKGROUND AND OBJECTIVE

COPD is a complex polygenic disease in which gene-environment interactions are very important. The gene encoding microsomal epoxide hydrolase (EPHX1) is one of several candidate loci for COPD pathogenesis and is highly polymorphic. Based chi on the polymorphisms of EPHX1 gene (tyrosine/histidine 113, histidine/arginine 139), the population can be classified into four groups of putative EPHX1 phenotypes (fast, normal, slow and very slow). A number of studies have investigated the association between the genotypes and phenotypes of EPHX1 and COPD susceptibility in different populations, with inconsistent results. A systematic review and meta-analysis of the published data was performed to gain a clearer understanding of this association.

METHODS

The MEDLINE database was searched for case-control studies published from 1966 to August 2007. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

Sixteen eligible studies, comprising 1847 patients with COPD and 2455 controls, were included in the meta-analysis. The pooled result showed that the EPHX1 113 mutant homozygote was significantly associated with an increased risk of COPD (OR 1.59, 95% CI: 1.14-2.21). Subgroup analysis supported the result in the Asian population, but not in the Caucasian population. When the analysis was limited to only the larger-sample-size studies, studies in which controls were in Hardy-Weinberg equilibrium and studies in which controls were smokers/ex-smokers, the pooled results supported the conclusion. The EPHX1 139 heterozygote protected against the development of COPD in the Asian population, but not in the Caucasian population. The other gene types of EPHX1 113 and EPHX1 139 were not associated with an increased risk of COPD. The slow activity phenotype of EPHX1 was associated with an increased risk of COPD. The fast activity phenotype of EPHX1 was a protective factor for developing COPD in the Asian population, but not in the Caucasian population. However, the very slow activity phenotype of EPHX1 was a risk for developing COPD in the Caucasian population, but not in the Asian population.

CONCLUSIONS

The polymorphisms of EPHX1 113 and EPHX1 139 are genetic contributors to COPD susceptibility in Asian populations. The phenotypes of EPHX1 were contributors to overall COPD susceptibility.

Nrf2-dependent sulfiredoxin-1 expression protects against cigarette smoke-induced oxidative stress in lungs

Oxidative stress results in protein oxidation and is involved in the pathogenesis of lung diseases such as chronic obstructive pulmonary disorder (COPD). Sulfiredoxin-1 (Srx1) catalyzes the reduction of cysteine sulfinic acid to sulfenic acid in oxidized proteins and protects them from inactivation. This study examined the mechanism of transcriptional regulation of Srx1 and its possible protective role during oxidative stress associated with COPD. Nrf2, a transcription factor known to influence susceptibility to pulmonary diseases, upregulates Srx1 expression during oxidative stress caused by cigarette smoke exposure in the lungs of mice. Disruption of Nrf2 signaling by genetic knockout in mice or RNAi in cells downregulated the expression of Srx1. In silico analysis of the 5'-promoter-flanking region of Srx1 identified multiple antioxidant-response elements (AREs) that are highly conserved. Reporter and chromatin-immunoprecipitation assays demonstrated that ARE1 at -228 is critical for the Nrf2-mediated response. Attenuation of Srx1 expression with RNAi potentiated the toxicity of hydrogen peroxide (H2O2), whereas overexpression of Srx1 protected against H2O2-mediated cell death in vitro. Immunoblot analysis revealed dramatic decreases in Srx1 expression in lungs from patients with COPD relative to nonemphysematous lungs together with a decline in Nrf2 protein. Thus, Srx1, a key Nrf2-regulated gene, contributes to protection against oxidative injury in the lung.

Glutathione S-transferase and microsomal epoxide hydrolase gene polymorphisms and risk of chronic obstructive pulmonary disease in Slovak population

AIM

To determine the risk of chronic obstructive pulmonary disease (COPD) associated with polymorphisms in the glutathione S-transferase (GST) M1, GST T1, and microsomal epoxide hydrolase (EPHX1) genes in a cohort of Slovak population.

METHODS

Two hundred and seventeen patients with the diagnosis of COPD and 160 control subjects were enrolled in the study. Blood samples were collected from all subjects and the DNA from peripheral blood lymphocytes was used for subsequent genotyping assays, using polymerase chain reaction and restriction fragment-length polymorphism methods.

RESULTS

In an unadjusted model, an increased risk for COPD was observed in subjects with EPHX1 His113-His113 genotype (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.20-4.69; P=0.008), compared with the carriers of the Tyr113 allele. However, after the adjustments for age, sex, and smoking status, the risk was not significant (adjusted OR, 1.79; 95% CI, 0.91-3.53; P=0.093). In a combined analysis of gene polymorphisms, the genotype combination EPHX1 His113-His113/GSTM1 null significantly increased the risk of COPD in both, unadjusted (OR, 5.08; 95% CI, 1.70-20.43; P=0.001) and adjusted model (OR, 4.87; 95% CI, 1.57-15.13; P=0.006).

CONCLUSION

Although none of the tested gene polymorphisms was significantly related to an increased risk of COPD alone, our results suggest that the homozygous exon 3 mutant variant of EPHX1 gene in the combination with GSTM1 null genotype is a significant predictor of increased susceptibility to COPD in the Slovak population. The findings of the present study emphasize the importance of detoxifying and antioxidant pathways in the pathogenesis of COPD.

Decline in NRF2-regulated antioxidants in chronic obstructive pulmonary disease lungs due to loss of its positive regulator, DJ-1

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.

Chronic obstructive pulmonary disease in patients who have HIV infection

An increased prevalence of chronic obstructive pulmonary disease (COPD) among persons who have HIV infection has raised the possibility that HIV may predispose to the development or progression of COPD. This article reviews the evidence that supports an association between HIV infection and COPD-namely emphysema and chronic bronchitis-and studies that suggest an association between HIV infection and small airways abnormalities and nonspecific airway hyper-responsiveness. Risk factors for COPD and potential reasons for an increased risk for COPD in HIV-positive patients are discussed. In addition, issues in the management of COPD in HIV-positive patients are reviewed.

Endothelial nitric oxide synthase gene variants contribute to oxidative stress in COPD

Nitric oxide (NO) plays critical role in endothelial dysfunction and oxidative stress in COPD, pointing to the significance of endothelial nitric oxide synthase gene (eNOS) variants. We investigated the association of -786T/C, -922A/G, 4B/4A, and 894G/T polymorphisms of eNOS with the disease and its impact on nitrite and malonaldehyde levels in 190 COPD patients and 134 healthy controls, all smokers. The -786C, -922G and 4A alleles were significantly over-represented in patients (p=0.02, p=0.02, and p=0.03, respectively). The haplotypes, -786C:4A, 4A:894G, -786C:894G, and -786C:4A:894G were significantly over-represented in patients (p<0.0001, p =0.02, p=0.02, and p <0.0001, respectively), whereas, haplotypes, -786T:4B, 4B:894G, -786T:894G, and -786T:4B:894G were significantly under-represented in the patients (p<0.0001). The patients had significantly increased levels of nitrite (p=0.003) and malonaldehyde (p<0.0001). Combination of genotypes containing -786C and 4A alleles were greater in patients (p 0.05), and these combinations associated with decreased FEV1 value and nitrite level (p=0.03 and p=0.04, respectively) and with increased malonaldehyde levels (p=0.02). The eNOS -786C, -922G, and 4A alleles, these alleles associated haplotypes and genotype combinations were over-represented in patients. The variants and their combinations of four polymorphisms of eNOS contribute to disturbed pulmonary function and oxidative stress in COPD.

Development of a novel microarray methodology for the study of SNPs in the promoter region of the TNF-α gene—Their association with obstructive pulmonary disease in Greek patients

OBJECTIVES

Polymorphisms in promoter region of TNF-alpha gene were shown to interfere with the transcriptional activity of the gene resulting in the production of different levels of TNF-alpha product suggesting their involvement in susceptibility or severity of many inflammatory diseases. We set up a case-control study consisting of 117 COPD (Chronic Obstructive Pulmonary Disease), 62 DB (bronchiectasis) patients and two control groups (109 smokers without COPD-healthy smokers control group and 212 general population subjects) to evaluate involvement of TNF-alpha gene polymorphisms in the abovementioned diseases in a homogeneous population.

METHODS

The novel methodology of the NanoChip Molecular Biology Workstation (MBW Nanogen http://www.nanogen.com) was employed to genotype the 5 promoter SNPs.

RESULTS AND CONCLUSIONS

Genotype frequencies of the 5 SNPs showed no significant difference between the COPD and DB patient groups and the healthy smokers group. Statistical difference (p=0.043) was only revealed between the haplotype frequencies in COPD patients compared to the general population control group. The NanoChip MBW is an accurate method for SNP screening.

Plasma levels of alpha1-antichymotrypsin and secretory leukocyte proteinase inhibitor in healthy and chronic obstructive pulmonary disease (COPD) subjects with and without severe alpha1-antitrypsin deficiency

BACKGROUND

Individuals with severe Z alpha1-antitrypsin (AAT) deficiency have a considerably increased risk of developing chronic obstructive lung disease (COPD). It has been hypothesized that compensatory increases in levels of other protease inhibitors mitigate the effects of this AAT deficiency. We analysed plasma levels of AAT, alpha1-antichymotrypsin (ACT) and secretory leukocyte protease inhibitor (SLPI) in healthy (asymptomatic) and COPD subjects with and without AAT deficiency.

METHODS

Studied groups included: 71 asymptomatic AAT-deficient subjects (ZZ, n = 48 and SZ, n = 23, age 31 +/- 0.5) identified during Swedish neonatal screening for AAT deficiency between 1972 and 1974; age-matched controls (MM, n = 57, age 30.7 +/- 0.6); older asymptomatic ZZ (n = 10); healthy MM (n = 20, age 53 +/- 9.6); and COPD patients (ZZ, n = 10, age 47.4 +/- 11 and MM, n = 10, age 59.4 +/- 6.7). Plasma levels of SLPI, AAT and ACT were analysed using ELISA and immunoelectrophoresis.

RESULTS

No significant difference was found in plasma ACT and SLPI levels between the healthy MM and the ZZ or SZ subjects in the studied groups. Independent of the genetic variant, subjects with COPD (n = 19) had elevated plasma levels of SLPI and ACT relative to controls (n = 153) (49.5 +/- 7.2 vs 40.7 +/- 9.1 ng/ml, p < 0.001 and 0.52 +/- 0.19 vs 0.40 +/- 0.1 mg/ml, p < 0.05, respectively).

CONCLUSION

Our findings show that plasma levels of ACT and SLPI are not elevated in subjects with genetic AAT deficiency compared MM controls and do not appear to compensate for the deficiency of plasma AAT.

Analysis of systemic biomarkers in COPD patients

The finding that alphal-antitrypsin (AAT) deficiency, PiZZ, a well-established genetic risk factor for COPD, is related to high levels of circulating AAT polymers, prompted us to measure serum levels of such polymers and selected markers of inflammation in age- and gender-matched patients with stable COPD and control subjects with and without severe AAT deficiency, and to assess their relationship with each other and with the genetic AAT-variant. We found that COPD individuals (n= 20), independent of AAT-variant, had significantly higher serum levels of AAT and its polymers, MMP-9, sICAM-1, VEGF and sE-selectin than controls (n=30). Subjects with PiZZ COPD (n= 10) showed significantly elevated serum levels of AAT-polymers, sE-selectin and sICAM-1, while patients with PiMM COPD (n= 10) showed higher levels of MMP-9, VEGF, IL-8 and MCP-1 than controls. By using factor analysis we were able to split the analysed biomarkers into two independent components: the first containing MMP-9, MCP-1, IL-8 and VEGF and the second-AAT and its polymers and sE-selectin. The result from the binomial logistic regression showed that 95.2 percent of the control individuals and 94.7 percent of the COPD patients can be correctly classified on the basis of the measured serum biomarkers. These observations highlight the importance of the finding sets of biomolecules, which could offer new strategies for the diagnosis of COPD and may have value for monitoring progression of COPD.

The value of forced expiratory volume in 1 second decline in the assessment of chronic obstructive pulmonary disease progression

Forced expiratory volume in 1 second (FEV1) declines normally with aging by approximately 30 mL/yr, but in susceptible smokers, the decline is greater (about 60 mL/yr), resulting in the development of chronic obstructive pulmonary disease (COPD). Smoking cessation usually restores the normal or near-normal rate of FEV1 decline, whereas intermittent quitting provides less benefit. Thus, smoking cessation is a critical component for the prevention of COPD progression. FEV1 is central to the definition of COPD and classification of its severity. FEV1 is a good predictor of exercise tolerance and correlates with survival and quality of life. More rapid FEV1 decline is also predictive of morbidity, mortality, and hospitalization rates. Risk factors for accelerated decline in FEV1, in addition to smoking, include frequent exacerbations, airways reactivity, and possibly chronic systemic inflammation. Genetic components of the decline in FEV1 are being actively explored, but none has been extensively validated other than alpha1-antitrypsin deficiency. To date, only smoking cessation has been definitively shown to be effective in reducing the rate of FEV1 decline, but other therapeutic strategies are under active research. Consequently, FEV1 and its change over time are important outcomes in COPD and valuable measures for the assessment of disease progression.

Do native and polymeric alpha1-antitrypsin activate human neutrophils in vitro?

BACKGROUND

alpha(1)-Antitrypsin (AAT)-Z deficiency is a risk factor for the development of COPD. Compared to wild-type M, AAT-Z has an increased tendency to polymerize, rendering it inactive as a serine proteinase inhibitor. It has been demonstrated that wild-type M- and Z-deficiency AAT polymers are chemotactic for human neutrophils. However, our own studies dispute a proinflammatory role for polymerized AAT-M and AAT-Z, suggesting rather that they are predominantly antiinflammatory, exhibiting inhibitory effects on lipopolysaccharide-stimulated human monocyte activation. The discrepancies between these observations prompted us to re-examine the effects of AAT.

METHODS AND RESULTS

The effects of native and polymerized AAT-M and AAT-Z with varying levels of endotoxin contamination (0.08 to 2.55 endotoxin units [EU]/mg protein) on human neutrophil chemotaxis and interleukin (IL)-8 release, in vitro, were evaluated. Neither native nor polymerized (M- or Z-deficient) AAT contaminated with low levels of endotoxin (</= 0.08 EU/mg protein) stimulated neutrophil chemotaxis, whereas N-formyl methionyl leucyl phenylalanine (fMLP), a positive control, increased chemotaxis fourfold. A small but nonsignificant increase in neutrophil chemotaxis, however, was observed with AAT preparations containing higher levels of endotoxin (>/= 0.88 EU/mg protein), and significant chemotaxis occurred when AAT was spiked with either endotoxin or zymosan. In support, native and polymeric AAT-M with low endotoxin contamination completely inhibited neutrophil IL-8 release triggered by the zymosan, while AATs with high endotoxin contamination strongly induced IL-8 release and did not inhibit zymosan-stimulated IL-8 release.

CONCLUSIONS

The proinflammatory effects of native and polymeric AAT may be critically dependent on the presence of other cell activators, bacterial or otherwise, while pure preparations of AAT appear to exert predominantly antiinflammatory activity.

Polymorphisms of p53 and p21 genes in chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a multifactorial disease influenced by genetic and environmental factors, particularly cigarette smoking. Although cigarette smoke may be directly mutagenic, polymorphisms in the genes controlling acquired somatic mutations may also contribute, at least to some extent, to the observed differing susceptibilities to COPD. To investigate the involvement of genetic polymorphisms of p53 and p21 in the pathogenesis of COPD, the authors performed a case-control study involving 206 subjects with COPD and 210 healthy smokers as control subjects.

METHODS

Polymorphisms of p53 and p21 genes were analyzed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique on genomic DNA isolated from peripheral lymphocytes. The distribution of the p53 and p21 polymorphisms in healthy subjects and COPD patients was examined and compared using the Pearson X2 test. Significance was accepted at P < 0.05. Odds ratios (ORs) and 95% confidence intervals (CIs) of each specific genotype were calculated using logistic regression analysis to quantitatively assess the degree of association observed.

RESULTS

The distribution frequencies of genotypes of p53 codon 72 and p21 codon 31 were significantly different between the COPD and the control groups. Higher ORs for COPD were seen for persons with p53 Pro/Pro or Pro/Arg genotypes against Arg/Arg genotype [OR = 2.35, 95% CI 1.27-4.39, P = 0.008], or p21 Arg/Arg and Arg/Ser genotypes against Ser/Ser genotype [OR = 2.07, 95% CI 1.06-4.05, P = 0.033].

CONCLUSIONS

The polymorphisms of p53 and p21 were significantly associated with the occurrence of smoking-related COPD in Taiwan Chinese patients.

Association of the ASP299GLY TLR4 polymorphism with COPD

Bacterial infection and colonization plays an important role in COPD. The inflammatory response to these bacteria is mediated by Toll-like receptors. The Asp299Gly polymorphism of the Toll-like receptor-4 (TLR4) has been shown to be associated with decreased lipopolysaccharide (LPS) signal transduction resulting in impaired antimicrobial defense. Because altered TLR4 signalling may facilitate bacterial infection, we clinically phenotyped and genotyped 152 patients with COPD (including 24 non-smokers), and 444 healthy controls for the presence of the Asp299Gly polymorphism. Frequencies of the TLR4 Gly allele (4% vs. 8% in controls, odds ratio (OR) 2.24 (95% confidence interval (95%CI) 1.17-4.3)) as well as TLR4 Gly genotype (6% vs. 13% in controls, OR 2.39 (95%CI 1.20-4.79)) were significantly decreased among the patients with COPD. The TLR4 Gly allele was not detected at all in a subgroup of non-smoking patients (n=24). We conclude that the frequency of the Asp299Gly polymorphism is decreased in COPD patients. Unaltered LPS signal transduction by TLR4 may be important for the development of COPD.

Interferon gamma polymorphisms and their interaction with smoking are associated with lung function

Interactions between genetic and environmental determinants are likely to be important in the pathogenesis of chronic obstructive pulmonary disease. We hypothesized that interferon gamma (IFNG) single nucleotide polymorphisms (SNPs) and their interaction with smoking are associated with the rate of decline or level of lung function in smokers. We studied four SNPs in IFNG in 585 non-Hispanic whites (NHW) who had the fastest (n =280) or the slowest (n=305) decline of FEV(1)% predicted selected from among continuous smokers followed for 5 years in the NHLBI Lung Health Study. We also studied 1061 NHW with the lowest (n=530) or the highest (n=531) baseline lung function at the beginning of the LHS. Two SNPs were associated with baseline levels of lung function and the p values were 0.008 for +2197T/C in a dominant model and 0.002 for +5171A/G in a recessive model. However, after adjusting for confounding factors, only +5171A/G was still significant (p=0.001 for the recessive model). In addition, there was a significant genotype and smoking interaction with p=0.006 for the +5171A/G (GG vs.GA + AA) for the baseline lung function. When comparing individuals with GG versus individuals with AG + AA for low lung function, the adjusted odds ratios decreased significantly as pack-years increased. No association was found in the rate of decline study. There was an association between IFNG genotype and baseline of lung function and this association was modified by cigarette smoking.

Genetic association analysis of functional impairment in chronic obstructive pulmonary disease

RATIONALE

Patients with severe chronic obstructive pulmonary disease (COPD) may have varying levels of disability despite similar levels of lung function. This variation may reflect different COPD subtypes, which may have different genetic predispositions.

OBJECTIVES

To identify genetic associations for COPD-related phenotypes, including measures of exercise capacity, pulmonary function, and respiratory symptoms.

METHODS

In 304 subjects from the National Emphysema Treatment Trial, we genotyped 80 markers in 22 positional and/or biologically plausible candidate genes. Regression models were used to test for association, using a test-replication approach to guard against false-positive results. For significant associations, effect estimates were recalculated using the entire cohort. Positive associations with dyspnea were confirmed in families from the Boston Early-Onset COPD Study.

RESULTS

The test-replication approach identified four genes-microsomal epoxide hydrolase (EPHX1), latent transforming growth factor-beta binding protein-4 (LTBP4), surfactant protein B (SFTPB), and transforming growth factor-beta1 (TGFB1)-that were associated with COPD-related phenotypes. In all subjects, single-nucleotide polymorphisms (SNPs) in EPHX1 (p < or = 0.03) and in LTBP4 (p < or = 0.03) were associated with maximal output on cardiopulmonary exercise testing. Markers in LTBP4 (p < or = 0.05) and SFTPB (p = 0.005) were associated with 6-min walk test distance. SNPs in EPHX1 were associated with carbon monoxide diffusing capacity (p < or = 0.04). Three SNPs in TGFB1 were associated with dyspnea (p < or = 0.002), one of which replicated in the family study (p = 0.02).

CONCLUSIONS

Polymorphisms in several genes seem to be associated with COPD-related traits other than FEV(1). These associations may identify genes in pathways important for COPD pathogenesis.

Mild and moderate-to-severe COPD in nonsmokers: distinct demographic profiles

STUDY OBJECTIVE

To investigate the risk of COPD among nonsmokers.

DESIGN

Case-control study, logistic regression analysis.

SETTING

Third National Health and Nutrition Examination Survey, from 1988 to 1994.

PARTICIPANTS

Community residents 18 to 80 years of age, of white, black, or Mexican-American ethnicity. Nonsmokers included never-smokers and former smokers with a < 5 pack-year smoking history who had never smoked cigars or pipes.

MEASUREMENTS

COPD (FEV1/FVC < 70%) was classified as mild (FEV1 > or = 80% predicted) or moderate to severe (FEV1 23 to 79% predicted).

RESULTS

Among 13,995 examinees, 51.3 +/- 0.4% were female, mean age was 42.2 +/- 0.4 years, 48.7 +/- 0.9% were nonsmokers, 8.8 +/- 0.3% had mild COPD, and 4.1 +/- 0.3% had moderate-to-severe COPD [+/- SE]. One fourth of mild and moderate-to-severe cases were nonsmokers. Among 7,526 nonsmokers, 4.7 +/- 0.3% had mild COPD (n = 403; age, 60.9 +/- 1.3 years) and were mostly female (82.5%), while 1.9 +/- 0.3% had moderate-to-severe COPD (n = 92, age 39.3 +/- 1.3) and were mostly male (88.1%). Few nonsmokers with COPD (12.1 +/- 2.4%) had a previous diagnosis of chronic bronchitis or emphysema. Among nonsmokers, physician-diagnosed asthma increased the risk of mild and especially of moderate-to-severe COPD. Independently of asthma, risk of mild COPD in nonsmokers increased with age (doubling every 12 years), before age 60 was lower among men than women, and was inversely associated with current exposure to tobacco smoke at home and at work. In contrast, the risk of moderate-to-severe COPD in nonsmokers was markedly associated with male gender, peaked in middle age, and was inversely associated with nonwhite ethnicity. COPD risks did not vary by minimal smoking history, longest-held occupation, urban residence, income, allergies, thyroid disease, or Helicobacter pylori antibody.

CONCLUSIONS

Among nonsmokers, mild and moderate-to-severe COPD are associated with asthma but otherwise have distinct demographic profiles, suggesting that moderate-to-severe disease is not a mere progression of mild COPD.

Alpha1-antitrypsin inhibits Moraxella catarrhalis MID protein-induced tonsillar B cell proliferation and IL-6 release

Alpha1-antitrypsin (AAT) is a major circulating and tissues inhibitor of serine proteinases implicated in the regulation of inflammation and host defence. There is now increasing evidence that AAT may also exhibit anti-inflammatory activities independent of its protease inhibitor function. This study was undertaken to investigate the effects of native (inhibitory) and polymerized (non-inhibitory) forms of AAT on MID (Moraxella IgD binding protein)-induced human tonsillar B cell activation in vitro. We found that 0.5 microg/ml MID induces B cell proliferation and stimulates IL-6 release (p<0.001) relative to non-stimulated controls. Both native and polymerized AAT (0.5 mg/ml) inhibited MID-stimulated B cell proliferation in a similar manner (by 70%, p<0.001), whereas MID-induced IL-6 release was more strongly suppressed by polymerized (9.9-fold, p<0.001) as compared to native AAT (2.8-fold, p<0.01). Electrophoretic analysis of cell culture media did not indicate any interaction between AAT and MID, and flow cytometry data showed no competition for the same receptor. The effects of AATs were observed whether added together with MID or 2h after MID-addition to cell cultures. Thus, our data demonstrate that AAT inhibits MID-induced B cell activation in vitro that is unrelated to its protease inhibitory activity and is not dependent on MID binding to the cell surface.

Association of the PIM3 allele of the alpha-1-antitrypsin gene with chronic obstructive pulmonary disease

OBJECTIVE

The study investigated the association of genetic polymorphism of the alpha1AT gene with COPD.

DESIGN AND METHODS

The mutations and polymorphism of alpha1AT gene were investigated by DNA sequence analysis using polymerase chain reaction.

RESULTS

The frequency of the PIM3 allele in COPD patients was found to be significantly higher than the controls (P < 0.0001). Five SNPs, including a novel SNP (24_25insA), were observed near the junction of exon-intron I. The occurrence of these SNPs didn't show any association with COPD. However, the PIM3 allele of the alpha1AT gene was found to be associated with COPD.

CONCLUSION

The PIM3 allele of the alpha1AT gene is found to have an association with the pathogenesis of COPD in the Indian population.

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

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

Prolastin, a pharmaceutical preparation of purified human alpha1-antitrypsin, blocks endotoxin-mediated cytokine release

BACKGROUND

Alpha1-antitrypsin (AAT) serves primarily as an inhibitor of the elastin degrading proteases, neutrophil elastase and proteinase 3. There is ample clinical evidence that inherited severe AAT deficiency predisposes to chronic obstructive pulmonary disease. Augmentation therapy for AAT deficiency has been available for many years, but to date no sufficient data exist to demonstrate its efficacy. There is increasing evidence that AAT is able to exert effects other than protease inhibition. We investigated whether Prolastin, a preparation of purified pooled human AAT used for augmentation therapy, exhibits anti-bacterial effects.

METHODS

Human monocytes and neutrophils were isolated from buffy coats or whole peripheral blood by the Ficoll-Hypaque procedure. Cells were stimulated with lipopolysaccharide (LPS) or zymosan, either alone or in combination with Prolastin, native AAT or polymerised AAT for 18 h, and analysed to determine the release of TNFalpha, IL-1beta and IL-8. At 2-week intervals, seven subjects were submitted to a nasal challenge with sterile saline, LPS (25 microg) and LPS-Prolastin combination. The concentration of IL-8 was analysed in nasal lavages performed before, and 2, 6 and 24 h after the challenge.

RESULTS

In vitro, Prolastin showed a concentration-dependent (0.5 to 16 mg/ml) inhibition of endotoxin-stimulated TNFalpha and IL-1beta release from monocytes and IL-8 release from neutrophils. At 8 and 16 mg/ml the inhibitory effects of Prolastin appeared to be maximal for neutrophil IL-8 release (5.3-fold, p < 0.001 compared to zymosan treated cells) and monocyte TNFalpha and IL-1beta release (10.7- and 7.3-fold, p < 0.001, respectively, compared to LPS treated cells). Furthermore, Prolastin (2.5 mg per nostril) significantly inhibited nasal IL-8 release in response to pure LPS challenge.

CONCLUSION

Our data demonstrate for the first time that Prolastin inhibits bacterial endotoxin-induced pro-inflammatory responses in vitro and in vivo, and provide scientific bases to explore new Prolastin-based therapies for individuals with inherited AAT deficiency, but also for other clinical conditions.

Models of chronic obstructive pulmonary disease

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.

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.

Burden and clinical features of chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a major cause of chronic morbidity and mortality and represents a substantial economic and social burden throughout the world. It is the fifth leading cause of death worldwide and further increases in its prevalence and mortality are expected in the coming decades. The substantial morbidity associated with COPD is often underestimated by health-care providers and patients; likewise, COPD is frequently underdiagnosed and undertreated. COPD develops earlier in life than is usually believed. Tobacco smoking is by far the major risk for COPD and the prevalence of the disease in different countries is related to rates of smoking and time of introduction of cigarette smoking. Contribution of occupational risk factors is quite small, but may vary depending on a country's level of economic development. Severe deficiency for alpha-1-antitrypsin is rare and the impact of other genetic factors on the prevalence of COPD has not been established. COPD should be considered in any patient presenting with cough, sputum production, or dyspnoea, especially if an exposure to risk factors for the disease has been present. Clinical diagnosis needs to be confirmed by standardised spirometric tests in the presence of not-fully-reversible airflow limitation. COPD is generally a progressive disease. Continued exposure to noxious agents promotes a more rapid decline in lung function and increases the risk for repeated exacerbations. Smoking cessation is the only intervention shown to slow the decline. If exposure is stopped, the disease may still progress due to the decline in lung function that normally occurs with aging, and some persistence of the inflammatory response.

Inhibition of lipopolysaccharide-mediated human monocyte activation, in vitro, by α1-antitrypsin

alpha1-Antitrypsin (AAT) is a major circulating and tissue inhibitor of serine proteinases. As such AAT is thought to play an important role in limiting host tissue injury at sites of inflammation. There is now increasing evidence, however, that AAT may exhibit biological activity independent of its protease inhibitor function. In this study we compared the effects of native (inhibitory) and modified (non-inhibitory), e.g., polymerised and oxidised forms of AAT on LPS-induced human monocyte activation, in vitro. We found that native AAT inhibited LPS-stimulated synthesis and release of TNFalpha and IL-1beta mRNA and protein, respectively, but enhanced the release of the anti-inflammatory cytokine, IL-10. Similarly, polymerised and oxidised forms of AAT inhibited LPS-stimulated IL-1beta and TNFalpha. The effects of AATs were observed whether added prior to or following removal of LPS, suggesting that sequestration of agonist was unlikely to explain their biological effects. Furthermore, studies with neutralising antibodies indicated that generation of IL-10 was unlikely to be the mechanism responsible for the inhibitory effects of AATs. Thus, our data demonstrate for the first time that AAT exhibits anti-inflammatory activity in vitro that is unrelated to inhibition of serine proteases.

Chronic obstructive pulmonary disease: importance of diagnosis

Chronic obstructive pulmonary disease is a common, smoking-related respiratory disease. It is responsible for considerable morbidity and mortality and accounts for a large amount of NHS resources. Despite this, it is underdiagnosed, often poorly managed and its impact on patients is underestimated (British Thoracic Society (BTS), 2001). The first step is to make an accurate diagnosis at as early a stage as possible. This article explores the prevalence, impact and presentation of the disease and how it can be identified and diagnosed.

Glutathione S-transferase variants and their interaction with smoking on lung function

We studied glutathione S-transferase (GST) polymorphisms in 1,098 whites with the lowest (n = 544, FEV(1) % predicted mean +/- SEM = 62.6 +/- 0.1) and the highest (n = 554, FEV(1) % predicted mean +/- SEM = 91.8 +/- 0.1) lung function at the beginning of the Lung Health Study. Homozygosity for GSTP1 105Val was significantly more frequent in the low- than in the high-function group (13.2 vs. 9.3%) (odds ratio = 1.69, 95% confidence interval [CI] = 1.11-2.61, p = 0.016), after adjustment for confounding variables. Subjects with 105Val homozygotes had higher rates of lung function decline in the high-function group (p = 0.017). The frequencies of GSTM1, GSTT1 null genotypes were similar between the high- and low-function groups, but subjects with the GSTT1 null genotype had a faster decline of lung function in the low-function group (p = 0.032). In addition, there was a significant interaction of GSTT1 genotype and pack-years on lung function. When comparing individuals with GSTT1 null genotype with wild type, the adjusted odds ratio was 3.49 (95% CI, 1.48-8.39, p = 0.005) in mild smokers (< or = 25 pack years). We conclude that GST genotypes are risk factors for rapid decline or low lung function in smokers with mild to moderate airflow obstruction.

Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major cause of death and disability worldwide. Recognition that the burden of this disorder will continue to increase over the next 20 years despite medical intervention has stimulated new research into the underlying mechanisms, leading to a rational basis for evaluation of existing therapies, and has suggested novel treatment approaches. Tobacco exposure remains the main but not exclusive cause of COPD. Whether the lung is injured by changes in the balance of proteases and antiproteases, tissue damage by oxidative stress, or a combination of the two is still not known. The genetic basis of susceptibility to COPD is now being studied as is the role of computed tomography in the identification of structural damage in individuals with less symptomatic disease. Clinical diagnosis still relies heavily on an appropriate history confirmed by abnormal spirometry. Smoking cessation is possible in a substantial proportion of individuals with symptoms but is most effective if withdrawal is supported by pharmacological treatment. Treatment with long-acting inhaled bronchodilators and, in more severe disease, inhaled corticosteroids reduces symptoms and exacerbation frequency and improves health status. Rehabilitation can be even more effective, at least for a year after the treatment. Recent guidelines have made practical suggestions about how to optimise these treatments and when to consider addition of oxygen, surgery, and non-invasive ventilation. Regular review of this guidance is important if future management advances are to be implemented effectively.

Variability of antioxidant-related gene expression in the airway epithelium of cigarette smokers

Cigarette smoking is the major risk factor for developing chronic bronchitis, yet only 15-20% of smokers develop this disorder. Because oxidants are the major mechanism of smoking-induced airway damage, we hypothesized that smoking is associated with upregulation of various antioxidant-related genes in the airway epithelium, but the magnitude of the response shows high inter-individual variability. Microarray analysis was used to assess levels of expression of 44 antioxidant-related genes in four categories (catalase/superoxide dismutase family; glutathione metabolism; redox balance; and pentose phosphate cycle) in bronchoscopy-obtained airway epithelium of matched cohorts (13 current smokers, 9 nonsmokers), none of whom had lung disease. There was minimal variation in gene expression levels within the same individual (right versus left lung or over time), but significant upregulation of 16/44 antioxidant-related genes in smoker epithelium compared with nonsmokers. Subgroups of smokers were identified with clusters of expression levels of antioxidant-related genes. We propose that the antioxidant-related genes demonstrating the most variability in the level of expression in smokers may be useful genetic markers in epidemiologic studies assessing susceptibility to smoking-induced chronic bronchitis.