Genetic susceptibility to chronic obstructive pulmonary disease in Koreans: combined analysis of polymorphic genotypes for microsomal epoxide hydrolase and glutathione S-transferase M1 and T1

GSTP1 rs4147581 C>G and NLRP3 rs3806265 T>C as Risk Factors for Chronic Obstructive Pulmonary Disease: A Case-Control Study

Background

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory ailment influenced by a blend of genetic and environmental factors. Inflammatory response and an imbalance in oxidative-antioxidant mechanisms constitute the primary pathogenesis of COPD. Glutathione S-transferase P1(GSTP1) plays a pivotal role as an antioxidant enzyme in regulating oxidative-antioxidant responses in the pulmonary system. The activation of the NOD-like receptor thermal protein domain (NLRP3) inflammatory vesicle can trigger an inflammatory response. Several investigations have implicated GSTP1 and NLRP3 in the progression of COPD; nonetheless, there remains debate regarding this mechanism.

Methods

Employing a case-control study design, 312 individuals diagnosed with COPD and 314 healthy controls were recruited from Gansu Province to evaluate the correlation between GSTP1 (rs4147581C>G and rs1695A>G) and NLRP3 (rs3806265T>C and rs10754558G>C) polymorphisms and the susceptibility to COPD.

Results

The presence of the GSTP1 rs4147581G allele substantially elevated the susceptibility to COPD (CGvs.CC:OR=3.11,95% CI=1.961-4.935, P<0.001;GGvs.CC:OR=2.065,95% CI=1.273-3.350, P=0.003; CG+GGvs.CC:OR=2.594,95% CI=1.718-3.916, P<0.001). Similarly, the NLRP3rs3806265T allele significantly increased the susceptibility to COPD (TC:TT:OR=0.432,95% CI=0.296-0.630; TC+CCvs.TT:OR=2.132,95% CI=1.479-3.074, P<0.001). However, no statistically significant association was discerned between the rs1695A>G and rs10754558G>C polymorphisms and COPD susceptibility (P>0.05).

Conclusion

In summary, this study ascertained that the GSTP1 rs4147581C>G polymorphism is associated with increased COPD susceptibility, with the G allele elevating the risk of COPD. Similarly, the NLRP3 rs3806265T>C polymorphism is linked to elevated COPD susceptibility, with the T allele heightening the risk of COPD.

GST polymorphism as a predictive biomarker for modulating the susceptibility to chronic obstructive pulmonary disease: A North Indian study

Chronic obstructive pulmonary disease (COPD) is commonly characterized by shortness of breath, coughing or expectoration. Smoking is the leading cause of COPD development, but only a small percentage of smokers develop symptoms, implying a genetic component. Glutathione S-transferase enzymes are responsible for detoxifying cigarette smoke components. The role of glutathione S-transferase T1 (GSTT1) and glutathione S-transferase M1 (GSTM1) gene polymorphism was assessed with COPD susceptibility and associated clinical parameters in the North Indian population. This was a cross-sectional study involving 200 COPD patients and 200 healthy individuals, with peripheral blood sampling and adequate questionnaires. Multiplex PCR was used for genotyping GSTT1 and GSTM1 gene polymorphism. Logistic regression was used to calculate the odds ratio and 95% confidence intervals to assess the COPD risk and GST polymorphisms. The GSTT1 gene deletion rate was higher in COPD cases (34.5%) than in healthy individuals (20.5%). A statistical relationship between the GSTT1(-) null genotype and COPD risk was observed (odds ratio = 2.04, 95% CI = 1.30-3.20, P = 0.0019). After adjusting for covariates like age, sex and smoking status, a significant association was found for GSTT1(-) null genotype and COPD risk (adjusted odds ratio = 2.90, 95% CI = 1.43-5.87, P = 0.003). The GSTT1(-) genotype was also significantly correlated with clinical parameters for COPD risk. Another primary observation was that females with the GSTT1(-) null genotype were more vulnerable to COPD than males with the same gene deletion. The GSTT1(-) null genotype strongly correlates with COPD development, while no association was observed in the GSTM1(-) null genotype in the North Indian population.

EPHX1 and GSTP1 polymorphisms are associated with COPD risk: a systematic review and meta-analysis

Background: Chronic obstructive pulmonary disease (COPD) affects approximately 400 million people worldwide and is associated with high mortality and morbidity. The effect of EPHX1 and GSTP1 gene polymorphisms on COPD risk has not been fully characterized. Objective: To investigate the association of EPHX1 and GSTP1 gene polymorphisms with COPD risk. Methods: A systematic search was conducted on 9 databases to identify studies published in English and Chinese. The analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines (PRISMA). The pooled OR and 95% CI were calculated to evaluate the association of EPHX1 and GSTP1 gene polymorphisms with COPD risk. The I² test, Q test, Egger's test, and Begg's test were conducted to determine the level of heterogeneity and publication bias of the included studies. Results: In total, 857 articles were retrieved, among which 59 met the inclusion criteria. The EPHX1 rs1051740 polymorphism (homozygote, heterozygote, dominant, recessives, and allele model) was significantly associated with high risk of COPD risk. Subgroup analysis revealed that the EPHX1 rs1051740 polymorphism was significantly associated with COPD risk among Asians (homozygote, heterozygote, dominant, and allele model) and Caucasians (homozygote, dominant, recessives, and allele model). The EPHX1 rs2234922 polymorphism (heterozygote, dominant, and allele model) was significantly associated with a low risk of COPD. Subgroup analysis showed that the EPHX1 rs2234922 polymorphism (heterozygote, dominant, and allele model) was significantly associated with COPD risk among Asians. The GSTP1 rs1695 polymorphism (homozygote and recessives model) was significantly associated with COPD risk. Subgroup analysis showed that the GSTP1 rs1695 polymorphism (homozygote and recessives model) was significantly associated with COPD risk among Caucasians. The GSTP1 rs1138272 polymorphism (heterozygote and dominant model) was significantly associated with COPD risk. Subgroup analysis suggested that the GSTP1 rs1138272 polymorphism (heterozygote, dominant, and allele model) was significantly associated with COPD risk among Caucasians. Conclusion: The C allele in EPHX1 rs1051740 among Asians and the CC genotype among Caucasians may be risk factors for COPD. However, the GA genotype in EPHX1 rs2234922 may be a protective factor against COPD in Asians. The GG genotype in GSTP1 rs1695 and the TC genotype in GSTP1 rs1138272 may be risk factors for COPD, especially among Caucasians.

Association of CYP1A2 and GST gene variants with asthma in cases presenting with allergic chronic rhinosinusitis

Background

Inter-individual differences in regulation and activity of xenobiotic metabolizing enzymes (XMEs) CYP1A and GST might cause distinct susceptibility to chronic rhinosinusitis (CRS) phenotypes that need to be explored. Therefore, the present study aimed to evaluate the role and risk of CYP1A and GST gene variants in allergic CRS subjects with and without asthma. A total of 224 allergic CRS cases with asthma, 252 allergic CRS cases without asthma, and 350 healthy control subjects were subjected to genetic analysis. Gene variants of cytochrome P450 (CYP1A1 T3801 rs4646903, A2455G rs1048943, C2453A rs1799814 and CYP1A2 G3858A rs2069514, T739G rs2069526, C163A rs762551) and glutathione S-transferase P (GSTP1 A313G rs1605 & C341T rs1799811) were investigated by polymerase chain reaction-restriction fragment length polymorphism and GSTM1null, and GSTT1null by multiplex PCR methods.

Results

TG genotype of CYP1A2 rs2069526 (OR 1.73, 95% CI 1.20–2.50, p < 0.002), TC genotype of CYP1A1 rs4646903 (OR 1.43, 95% CI 1.03–1.98, p < 0.031) and GSTM1del (OR 1.87, 95% CI 1.24–2.81, p < 0.003) and were found to be significantly associated with only allergic CRS cases. CYP1A2 rs2069526 (OR 2.33, 95% CI 1.61–3.37, p < 0.001), GG genotype of GSTP1 rs1605 (OR 4.75, 95% CI 2.62–8.63, p < 0.001), GSTM1del (OR 1.82, 95% CI 1.19–2.78, p < 0.006), GSTM1/GSTT1 double null (OR 2.58, 95% CI 1.36–4.87, p < 0.004) and were found to be significantly associated with asthma in allergic CRS cases. Further, G-G-C haplotype of CYP1A2 rs2069514, rs2069526 and rs762551 gene variants was found to increase the risk for asthma by 5 folds in allergic CRS subjects (OR 5.53, 95% CI 1.76–17.31, p < 0.003) while T-G-C haplotype of CYP1A1 rs4646903, rs1048943, rs1799814 (OR 0.11, 95% CI (0.01–0.95, p < 0.045) and A-T haplotype of GSTP1 rs1605, rs1799811 (OR 0.27, 95% CI (0.08–0.89, p < 0.032) showed protective effect in allergic CRS group.

Conclusion

The present study reports the significantly increased association of CYP1A2, GSTM, and GSTP gene variants with asthma in allergic CRS.

The Leucocyte Telomere Length, GSTM1 and GSTT1 Null Genotypes and the Risk of Chronic Obstructive Pulmonary Disease

Simple Summary

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation and oxidative stress, both in the airways and blood, and in other organs. Elevated oxidative stress and inflammation have been reported to affect leucocyte telomere length (LTL). We explored the link between GSTM1 and GSTT1 gene polymorphisms, LTL and COPD risk. For GSTM1 and GSTT1, we genotyped 152 COPD patients and 131 non-affected controls, while for TL, we assessed 91 patients and 88 controls. There was a significant difference in GSTM1 null genotype frequency between the patients and controls (0.59 vs. 0.38, p ≤ 0.000), but such was not found for GSTT1 (p = 0.192). COPD patients carrying the GSTM1 null genotype had shorter telomeres compared to those carrying the non-null genotype (15,720 bp vs. 22,442 bp, p = 0.008); and in controls, the opposite occurred (31,354 bp vs. 17,800 bp, p = 0.020). According to our results GSTM1, but not GSTT1, null genotypes might play role in leucocyte telomere shortening, and thus be involved in the pathogenesis of COPD.

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation and oxidative stress both in the airways and blood and other organs. Elevated oxidative stress and inflammation have been reported to affect leucocyte telomere length (LTL). Glutathione S-transferase (GST) enzymes are a large family of xenobiotic-metabolizing enzymes that utilize different ROS products. We aimed to explore the link between GSTM1 and GSTT1 gene polymorphisms, LTL and COPD risk. For GSTM1, we genotyped 152 COPD patients and 131 non-affected controls; for GSTT1, we genotyped 149 COPD patients and 130 controls. We were able to assess TL for 91 patients and 88 controls. There was a significant difference in the GSTM1 null genotype frequency between the patients and controls (0.59 vs. 0.38, p ≤ 0.000), but such was not found for GSTT1 (p = 0.192). When combining both polymorphisms, we obtained a significantly greater presence of at least one null genotype among patients (0.12 vs. 0.05, p = 0.027). An association between GSTT1 and LTL was not found. COPD patients carrying the GSTM1 null genotype had shorter telomeres compared to those carrying the non-null genotype (15,720 bp vs. 22,442 bp, p = 0.008); as for the controls, it was the opposite (31,354 bp vs. 17,800 bp, p = 0.020). The significance in both groups remained when combining GSTM1 and GSTT1 (COPD (at least one null) 16,409 bp vs. COPD (non-null) 22,092 bp, p = 0.029; control (at least one null) 29,666 bp vs. control (non-null) 16,370 bp, p = 0.027). The total glutathione level in GSTM1 non-null controls was higher compared to the null genotype (15.39 ng/mL vs. 5.53 ng/mL, p = 0.002). In COPD patients, we found no association (p = 0.301). In conclusion, according to our results, GSTM1, but not GSTT1, null genotypes might play a role in leucocyte telomere shortening, and thus be involved in the pathogenesis of COPD.

The Cumulative Effect of Gene-Gene Interactions Between GSTM1, CHRNA3, CHRNA5 and SOD3 Gene Polymorphisms Combined with Smoking on COPD Risk

Background

Chronic obstructive pulmonary disease (COPD) is a multifactorial disorder which is affected by external and internal risk factors. People with no external risk factors may be significantly affected and develop pulmonary disease. The study aimed to define gene–gene and gene–environmental effects on COPD.

Methods

A case control study involved 181 COPD patients and 292 healthy individuals, with peripheral blood sampling and adequate questionnaires. Genotyping was done with various types of PCR design for GSTM1 (null del), GSTT1 (null del), EPHX1 (rs2234922 and rs1051740), GSTP1 (rs1695 and rs1138272), CHRNA3 (rs1051730 and rs12914385), CHRNA5 (rs16969968 and rs17486278), and SOD3 (rs1799895 and rs699473) gene polymorphisms. Gene–gene and gene–environmental interactions were investigated using multidimensional regression analysis.

Results

Frequency of risk alleles of rs1051730 (p = 0.001), rs16969968 (p <0.001), and rs1799895 (p <0.001) polymorphisms were significant in univariate analysis. For gene–gene interaction, GSTM1 null, rs1051730, rs16969968, and rs1799895 polymorphisms independently contributed to risk of COPD and any combinations of the risk genotypes have a higher risk of disease. A cumulative effect of the four risk polymorphisms increased the risk of COPD for the smoking index (cOR = 13.6, p <0.001), cigarettes per day (cOR = 32.08, p <0.01), nicotine dependence (cOR = 12.0, p <0.01), and smoking status (cOR = 17.02, p <0.01) for gene–environmental interaction.

Conclusion

Several pivotal genes showed distinct effects for COPD, and some synergistic effects affected the disease progression. The development of COPD was synergistically increased with gene–gene and gene–environmental risk factors.

Genetic polymorphism and chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common chronic disease, and its morbidity and mortality are increasing. There are many studies that have tried to explain the pathogenesis of COPD from genetic susceptibility, to identify the susceptibility of COPD factors, which play a role in early prevention, early detection and the early treatment. However, it is well known that COPD is an inflammatory disease characterized by incomplete reversible airflow limitation in which genes interact with the environment. In recent years, many studies have proved gene polymorphisms and COPD correlation. However, there is less research on the relationship between COPD and genome-wide association study (GWAS), epigenetics and apoptosis. In this paper, we summarized the correlation between gene level and COPD from the following four aspects: the GWAS, the gene polymorphism, the epigenetics and the apoptosis, and the relationship between COPD and gene is summarized comprehensively.

Oxidative Stress and Genetic Variants of Xenobiotic-Metabolising Enzymes Associated with COPD Development and Severity in Serbian Adults

The genetic and non-genetic factors that contribute to the development of chronic obstructive pulmonary disease (COPD) are still poorly understood. We investigated the potential role of genetic variants of xenobiotic-metabolising enzymes (glutathione-S-transferase M1, GSTM1; glutathione-S-transferase T1, GSTT1; microsomal epoxide hydrolase, mEH), oxidative stress (assessed by urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine, 8-oxodG/creatinine), sex, ageing and smoking habits on susceptibility to development of COPD and its severity in Serbian population. The investigated population consisted of 153 healthy subjects (85 males and 68 females) and 71 patients with COPD (33 males and 38 females). Detection of GSTM1*null, GSTT1*null, mEH Tyr113His and mEH His139Arg gene variants was performed by PCR/RFLP method. Urinary 8-oxodG was determined using HPLC-MS/MS, and expressed as 8-oxodG/creatinine. We revealed that increased urinary 8-oxodG/creatinine and leucocytosis are the strongest independent predictors for COPD development. Increased level of oxidative stress increased the risk for COPD in males [odds ratio (OR), 95% confidence interval (CI): 8.42, 2.26-31.28], more than in females (OR, 95% CI: 3.60, 1.37-9.45). Additionally, independent predictors for COPD were ageing in males (OR, 95% CI: 1.29, 1.12-1.48), while in females they were at least one GSTM1 or GSTT1 gene deletion in combination (OR, 95% CI: 23.67, 2.62-213.46), and increased cumulative cigarette consumption (OR, 95% CI: 1.09, 1.01-1.16). Severity of COPD was associated with the combined effect of low mEH activity phenotype, high level of oxidative stress and heavy smoking. In conclusion, early identification of GSTM1*null or GSTT1*null genotypes in females, low mEH activity phenotype in heavy smokers and monitoring of oxidative stress level can be useful diagnostic and prognostic biomarkers.

Cigarette Smoke-Induced Hypermethylation of the GCLC Gene Is Associated With COPD

BACKGROUND

Cigarette smoking is a major environmental contributor to COPD, but understanding its epigenetic regulation of oxidative genes involved in the pathogenesis of COPD remains elusive.

METHODS

We analyzed DNA methylation on glutamate-cysteine ligase catalytic subunit (GCLC), glutathione S-transferase M1 (GSTM1), glutathione S-transferase P1 (GSTP1), and superoxide dismutase 3 (SOD3) promoters in clinical samples from patients with COPD (current-smoker [CS-COPD]; ex-smoker [ES-COPD]) and subjects with normal pulmonary function (current-smoker [CS-NS]; ex-smoker [ES-NS]; never-smoker [NC]). Expression of GCLC messenger RNA (mRNA) and glutathione (GSH) synthesis in these clinical samples and human bronchial epithelial (BEAS-2B) cells stimulated by cigarette-smoke extract (CSE) was evaluated. GCLC mRNA and protein levels were measured to determine effects of demethylation and deacetylation agents on CSE-treated BEAS-2B cells.

RESULTS

The DNA methylation level of the GCLC promoter was significantly increased in CS-COPD, CS-NS, and ES-COPD groups compared with ES-NS and NC groups. However, there were no significant differences in DNA methylation values of GSTM1, GSTP1, and SOD3 promoters among these groups. Expression of GCLC mRNA was downregulated in the lungs, and GSH levels decreased in plasma as a consequence of hypermethylation of the GCLC promoter. Similarly, CSE-treated BEAS-2B cells had hypermethylation of the GCLC gene, mRNA downregulation, and a decreased intracellular GSH level. GCLC expression in CSE-treated BEAS-2B cells was restored by the methylation inhibitor, 5-aza-2'-deoxycytidine, but not by the deacetylation agent, trichostatin A.

CONCLUSIONS

Cigarette smoke-induced hypermethylation of the GCLC promoter is related to the initiation and progression of COPD. Our finding may provide a new strategy for COPD intervention by developing demethylation agents targeting GCLC hypermethylation.

Association of Functional Variants of Phase I and II Genes with Chronic Obstructive Pulmonary Disease in a Serbian Population

Background

Chronic obstructive pulmonary disease (COPD) is a complex disorder characterized by increased oxidative stress. Functional genetic variants of phase I and II genes are implicated in oxidants–antioxidants imbalance and may be involved in COPD development. In this study, we aimed to investigate the role of cytochrome P450 (CYP), glutathione S-transferase (GST) and microsomal epoxide hydrolase (mEH) functional variants in the pathogenesis of COPD in a Serbian population.

Methods

The genotypes of 122 COPD patients and 100 controls with normal lung function were determined for CYP1A1 *1A/*2A, CYP2E1 *1A/*5B, GSTM1 null, GSTT1 null GSTP1 Ile105Val, mEH Tyr113His and mEH His139Arg gene variants.

Results

Results obtained showed that GSTM1 null variant was significantly more represented in COPD patients than in controls (61.5% vs. 47.0%; OR=1.80; p=0.042). Also, a significant difference was observed for combinations of GSTM1 null and GSTP1 105Val/(Val) (38.5% vs. 24.0%; OR=1.98; p=0.029), as well as for CYP1A1 *1A/*2A, GSTM1 null and mEH 113His/(His) genotypes (7.4% vs. 1.0%; OR=7.88; p=0.025).

Conclusions

These are the first data concerning the analysis of the variants of phase I and II genes in the pathogenesis of COPD in a Serbian population. Results obtained in this study open up the possibility for thorough analyses of the role of genetic factors in COPD on larger cohorts. Also, they implicate the importance of previously described genetic associations with COPD in our population, as well as reveal a new one, not reported so far.

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.

Expression of glutathione S-transferase variants in human airway wall after long-term response to sulfur mustard

CONTEXT

Sulfur mustard (SM) is an alkylating agent identified as a potent chemical warfare agent. More recently, SM was used in the Iraq conflict against Iranian troops and civilians. At present, there are many people suffering from chronic obstructive pulmonary disease (COPD) due to mustard gas in Iran. SM increases the endogenous production of reactive oxygen species (ROS). The oxidant/antioxidant imbalance present in the lungs of these patients also results from the impaired capacity of the antioxidant/detoxification enzymes to detoxify the harmful reactive oxygen metabolites.

OBJECTIVE

One of the major antioxidants in human airways is glutathione S-transferase. They facilitate the detoxification of various environmental of oxidative stress. In this study, we attempted to understand the significance different in expression of GSTs in airway wall of chemical patients and control.

MATERIALS AND METHODS

Seven normal and 20 SM induced COPD individuals were studied. Bronchoscopy was performed in all subjects and two specimens were taken from the main bronchus for mRNA extraction, PCR analysis and immunohistochemistry.

RESULTS

SM-induced COPD individuals showed expression of GSTA1 2.51 ± 0.83-, GSTM1 2.84 ± 1.71- and GSTP1 5.61 ± 2.59-folds higher than those of controls that revealed. GSTP1-immunoreactivity was strongly expressed in luminal border of normal samples. SM patient samples immunoreactivity for GSTP1 in the same area were negative.

DISCUSSION AND CONCLUSION

According to these findings, we speculated that overexpression of GSTs mRNA in patients revealed that GSTs plays an important role in cellular protection against oxidative stress of MS in airway wall of patients.

Genetic susceptibility

Why only 20% of smokers develop clinically relevant chronic obstructive pulmonary disease (COPD) was a puzzle for many years. Now, epidemiologic studies point clearly toward a large heritable component. The combination of genome-wide association studies and candidate gene analysis is helping to identify those genetic variants responsible for an individual's susceptibility to developing COPD. In this review, the current data implicating specific loci and genes in the pathogenesis of COPD are examined.

Genetic polymorphisms of GSTM1 and GSTT1 genes in Delhi and comparison with other Indian and global populations

The glutathione S-transferases (GSTs) are involved in the metabolism of many xenobiotics, including an array of environmental carcinogens, pollutants, and drugs. Genetic polymorphisms in these genes may lead to inter- individual variation in susceptibility to various diseases. In the present study, GSTM1 and GSTT1 polymorphisms were analysed using a multiplex polymerase chain reaction in 500 normal individuals from Delhi. The frequency of individuals with GSTM1 and GSTT1 null genotypes were 168 (33.6%) and 62 (12.4%) respectively, and 54 (10.8%) were having homozygous null genotype for both the genes GSTM1 and GSTT1 simultaneously. The studied population was compared with reported frequencies from other neighbouring state populations, as well as with those from other ethnic groups; Europeans, Blacks, and Asians. The prevalence of homozygous null GSTM1 genotype is significantly higher in Caucasians and Asians as compared to Indian population. The frequency of GSTT1 homozygous null genotypes is also significantly higher in blacks and Asians. We believe that due to large number of individuals in this study, our results are reliable estimates of the frequencies of the GSTM1, GSTT1 in Delhi. It would provide a basic database for future clinical and genetic studies pertaining to susceptibility and inconsistency in the response and/or toxicity to drugs known to be the substrates for GSTs.

Microsomal epoxide hydrolase gene polymorphisms and risk of chronic obstructive pulmonary disease: A comprehensive meta-analysis

Microsomal epoxide hydrolase (EPHX1) is an enzyme involved in the detoxification the products of smoking and is proposed to be a genetic factor for the development of chronic obstructive pulmonary disease (COPD). Two functional polymorphisms of EPHX1, T113C and A139G, have been analyzed in numerous studies to assess the COPD risk attributed to these variants. However, the conclusions were controversial. We performed a comprehensive meta-analysis to clarify these findings. A total of 24 studies comprising 8,259 COPD patients and 42,883 controls were included. The overall results showed that the EPHX1 113 mutant homozygote was significantly associated with an increased risk of COPD (OR, 1.33; 95% CI, 1.06-1.69). The subgroup analyses demonstrated this association in Caucasian individuals (OR, 1.61; 95% CI, 1.12-2.31) but not in Asian individuals. The 139 mutant heterozygote was significantly associated with a decreased risk of COPD in Asian populations (OR, 0.82; 95% CI, 0.68-0.99) but not in Caucasian populations. Pooled analyses revealed that the extremely slow (OR, 1.77; 95% CI, 1.23-2.55) and slow EPHX1 enzyme activity (OR, 1.44; 95% CI, 1.13-1.85) were associated with an increased risk of COPD, while the fast enzyme activity was not associated with a decreased risk of COPD. The stratified analysis demonstrated this association in Caucasian but not in Asian individuals. Furthermore, a modest difference in the risk of COPD was observed between the subgroups by using the cigarette smokers or the non-smokers as controls. A significant correlation between the two functional polymorphisms, T113C and A139G, of the EPHX1 gene and the enzyme activity and the individual's susceptibility to COPD was noted. In addition, the results supported a contribution of EPHX1 to the aetiology of COPD.

Updates on the COPD gene list

A genetic contribution to develop chronic obstructive pulmonary disease (COPD) is well established. However, the specific genes responsible for enhanced risk or host differences in susceptibility to smoke exposure remain poorly understood. The goal of this review is to provide a comprehensive literature overview on the genetics of COPD, highlight the most promising findings during the last few years, and ultimately provide an updated COPD gene list. Candidate gene studies on COPD and related phenotypes indexed in PubMed before January 5, 2012 are tabulated. An exhaustive list of publications for any given gene was looked for. This well-documented COPD candidate-gene list is expected to serve many purposes for future replication studies and meta-analyses as well as for reanalyzing collected genomic data in the field. In addition, this review summarizes recent genetic loci identified by genome-wide association studies on COPD, lung function, and related complications. Assembling resources, integrative genomic approaches, and large sample sizes of well-phenotyped subjects is part of the path forward to elucidate the genetic basis of this debilitating disease.

NFE2L2 pathway polymorphisms and lung function decline in chronic obstructive pulmonary disease

An oxidant-antioxidant imbalance in the lung contributes to the development of chronic obstructive pulmonary disease (COPD) that is caused by a complex interaction of genetic and environmental risk factors. Nuclear erythroid 2-related factor 2 (NFE2L2 or NRF2) is a critical molecule in the lung's defense mechanism against oxidants. We investigated whether polymorphisms in the NFE2L2 pathway affected the rate of decline of lung function in smokers from the Lung Health Study (LHS)(n = 547) and in a replication set, the Vlagtwedde-Vlaardingen cohort (n = 533). We selected polymorphisms in NFE2L2 in genes that positively or negatively regulate NFE2L2 transcriptional activity and in genes that are regulated by NFE2L2. Polymorphisms in 11 genes were significantly associated with rate of lung function decline in the LHS. One of these polymorphisms, rs11085735 in the KEAP1 gene, was previously shown to be associated with the level of lung function in the Vlagtwedde-Vlaardingen cohort but not with decline of lung function. Of the 23 associated polymorphisms in the LHS, only rs634534 in the FOSL1 gene showed a significant association in the Vlagtwedde-Vlaardingen cohort with rate of lung function decline, but the direction of the association was not consistent with that in the LHS. In summary, despite finding several nominally significant polymorphisms in the LHS, none of these associations were replicated in the Vlagtwedde-Vlaardingen cohort, indicating lack of effect of polymorphisms in the NFE2L2 pathway on the rate of decline of lung function.

The importance of epigenetics in the development of chronic obstructive pulmonary disease

It is generally accepted that genetic predisposition plays a role in COPD development in susceptible individuals. Therefore, many candidate genes that could be linked to the development of disease have been examined in COPD. However, inconsistent results in different study populations often limit this approach, suggesting that not only genetics, but also other factors, may be contributed to the susceptibility to COPD. Epigenetic mechanisms can affect the transcriptional activity of specific genes, at different points in time, and in different organs. Moreover, these mechanisms can have an effect on people's health. Recently, there is emerging evidence supporting a role of epigenetics for the regulation of inflammatory genes in diseases such as asthma and COPD. Moreover, recent studies suggest that the currently used treatments including corticosteroids may work through epigenetic mechanisms. Epigenetic regulation can be reprogrammed, potentially affecting the risk, aetiology and treatment of various disease states. The epigenetically influenced phenotype could be reversed with demethylating or deacetylating agents, consistent with epigenetic plasticity. The postnatal reversibility of these methylation or acetylation events may therefore provide good opportunities for intervention. The recognition of the role of genetic and epigenetic mechanisms in the development of COPD may identify novel targets that hatch new therapies for patients with COPD.

Update in chronic obstructive pulmonary disease: role of antioxidant and metabolizing gene polymorphisms

Chronic obstructive pulmonary disease (COPD) is characterized by systemic and local chronic inflammation and oxidative stress. The sources of the increased oxidative stress in COPD patients derive from the increased burden of inhaled oxidants such as cigarette smoke and other forms of particulate or gaseous air pollution and from the increase in reactive oxygen species (ROS) generated by several inflammatory, immune, and structural airways cells. There is increasing evidence that genetic factors may also contribute to the pathogenesis if COPD, particularly antioxidant genes, which may confer a susceptibility to environmental insults such as cigarette smoke and thereafter development of COPD. Consequently, heme oxygenase-1 (HO-1), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), microsomal epoxide hydrolase (EPHX1), and cytochrome P450 (CYP) genetic polymorphisms may have an important role in COPD pathogenesis. In this review the authors summarized the most recent findings dealing with these antioxidant genes contributing to the free radical neutralization and xenobiotic enzymes playing a role in different phases of cell detoxification reactions related to the redox status imbalance in COPD, with an emphasis on their possible roles in disease progression.

Association of genetic polymorphism of GSTT1, GSTM1 and GSTM3 in COPD patients in a north Indian population

Environmental exposures and genetic susceptibility can contribute to lung function decline in chronic obstructive pulmonary disease (COPD). Cigarette smoking is the main etiological factor for decline in lung function in COPD. However, only 10-20% chronic smokers develop symptomatic COPD. Genetic susceptibility to COPD might depend upon the variation of enzyme activities that detoxify cigarette smoke components. We performed a case control study to assess the association of Glutathione- S-transferase T1(GSTT1),Glutathione- S-transferase M1 (GSTM1), and Glutathione-S-transferase M3(GSTM3) common polymorphisms with the susceptibility to COPD patient in a north India population. In the present study, the genotypes of 412 subjects, (204 COPD patients and 208 healthy controls) were analyzed. Statistical analysis revealed that the frequency of homozygous GSTM1 null genotype was found to be significant higher in COPD patients as compared with healthy controls (OR, 2.58; 95% CI, 1.73-3.84; P = 0.001), but there were no significant differences in the distribution of homozygous null GSTT1 and 3-bp deletion polymorphism (rs1799735) in intron 6 variant allele in GSTM3 between COPD patients and healthy controls. Our study results suggest that GSTM1 null polymorphism is associated with genetic susceptibility to COPD. Moreover, we also found association between this polymorphism with pulmonary function test in smokers as well as nonsmokers.

Microsomal epoxide hydrolase gene polymorphisms and susceptibility to chronic obstructive pulmonary disease in the Tunisian population

It is well known that cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD). However, only 10%-20% of chronic heavy cigarette smokers develop symptomatic disease, which suggests the presence of genetic susceptibility. Microsomal epoxide hydrolase (EPHX1) is an enzyme involved in the protective mechanism against oxidative stress. It has been reported that gene polymorphisms of this enzyme may be associated with variations in EPHX1 activity. In this study, we aimed at investigating the relationship between EPHX1 polymorphisms and susceptibility to COPD in the Tunisian population. EPHX1 exon 3 (rs1051740, Tyr113His) and exon 4 (rs2234922, His139Arg) polymorphisms were genotyped by polymerase chain reaction followed by restriction fragment length polymorphism analysis. These techniques were used to examine a total of 416 Tunisian individuals, including 182 blood donors and a group of 234 COPD patients. All subjects were not related. An increased risk for COPD was observed in subjects with EPHX1 His113-His113 genotype (odds ratio = 2.168; confidence interval 1.098-4.283; p = 0.02386). However, multivariate logistic regression analysis showed no significant relationship between the mutant genotype and the disease after adjustment for sex, age, body mass index, smoking status, and pack-year smoking (odds ratio = 1.524; confidence interval, 0.991-6.058; p = 0.06137). Regarding the two subtypes of COPD, our investigations demonstrated that there is no significant correlation between exon 3 polymorphism and the chronic bronchitis subgroup (p = 0.09034). The relation between exon 3 polymorphism and emphysema was significant in the univariate analysis (p = 0.02257), but no association was found after controlling for classic risk factors (p = 0.06273). In conclusion, our results showed that there is a weak relation between 113His genotype and COPD, and no apparent relation between 139Arg and COPD in the studied Tunisian population.

Association of GSTM1T1 genes with COPD and prostate cancer in north Indian population

The glutathione S-transferase (GST) family of enzymes is known to play a pivotal role in phase II of biotransformation of xenobiotics, environmental carcinogens and pharmacological drugs. The objective of the present study was to investigate the role of GSTM1 and GSTT1 null genotypes as risk factors for chronic obstructive pulmonary disease (COPD) and prostate cancer. The subjects appraised were 200 COPD cases, 150 prostate cancer cases, 150 benign prostatic hyperplasia (BPH) cases, 200 age matched controls for COPD and 172 age matched controls for prostate cancer. GSTM1 and GSTT1 null genotype was found to confer 2.5 (OR 2.45; 95% CI 1.56-3.82; P value = 0.00008) and 2.4-fold (OR 2.39; 95% CI 1.36-4.20; P value = 0.002) significant higher risk for prostate cancer. Smoking imparted a 2.2-fold significant risk of prostate cancer cases (OR 2.23; 95% CI 1.36-3.65 P value = 0.001) and twofold risk in BPH (OR 2.09; 95% CI 1.26-3.46; P value = 0.005). In case of COPD only null genotype of GSTT1 has shown 2.1-fold (OR 2.11; 95% CI 1.22-3.62; P value = 0.007) significant increased risk.

GLUTATHIONE S-TRANSFERASE GENE POLYMORPHISM AND ISCHEMIC CEREBROVASCULAR DISEASE

Glutathione S-transferase polymorphisms (GST) were examined in 142 cases with ischemic cerebrovascular disease (ICVD) to explore whether the GST polymorphisms confer a risk to an individual to develop ICVD. Tobacco smoke is a major cause of both cancer and vascular disease. The subjects were therefore stratified with ICVD for smoking status, and then the authors examined whether polymorphisms in this detoxification enzyme gene, GST, influence risk of ICVD. The GST genotype was analyzed by the polymerase chain reaction. Neither GSTM1 nor GSTT1 genotypes in the ICVD group was significantly different from the control group (n=344), even in smokers. The authors attempted the combined analysis for GSTM1 and GSTT1 genotypes in ICVD for smoking status. No significant association was observed among the combined genotypes and ICVD. The observations do not confirm the effect of the GSTM1 and GSTT1 genotypes as a risk factor for ICVD, even in smokers. However, this approach provides a way of addressing the hypothesis that environmental genotoxins could play a role in the etiopathogenesis of ICVD.

The Association Between Polymorphisms in Glutathione S-Transferase (GSTM1andGSTT1) and Lung Cancer Outcome

BACKGROUND

Polymorphisms in the glutathione S-transferase (GST) family may be associated with increased risk of lung cancer, somatic changes in lung tumour tissue, and survival. We evaluated survival according to GST polymorphism in lung cancer patients.

METHODS

We studied DNA polymorphisms of 81 primary lung cancer patients at 2 glutathione-related loci: GSTM1, and GSTT1 that encode glutathione S-transferase-mu, and glutathione S-transferase- square. The presences of the GSTM1 and GSTT1 genes were assayed by PCR. Kaplan-Meier with log rank tests, and Cox regression models were applied in the analysis.

RESULTS

The median age of 75 males and 6 females was 60 years. Median survival of the whole population was 8 months. In the first presentation, none of the patients with GSTT1 null genotype but 30 percent of the patients with GSTT1-positive genotype had liver metastasis (p < 0.01) but GSTT1 genotype was not associated with survival. Sputum (p < 0.01) was more common in patients with GSTM1 null genotype. Subjects with the GSTM1-null genotype had shorter survival. Using a Cox proportional hazard model, GSTM1, tumor (T) factor and thoracic irradiation status were identified as independent prognostic factors.

CONCLUSIONS

Our preliminary results showed that GSTM1-null genotype was associated with shorter survival.

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.

PAH-DNA adducts in a Chinese population: relationship to PAH exposure, smoking and polymorphisms of metabolic and DNA repair genes

The present study was conducted in a Chinese population to evaluate the usefulness and sensitivity of PAH-DNA adduct as a biomarker of PAH exposure, and to examine the potential effects of smoking and polymorphisms of responsive genes on DNA adduct formation induced by PAH exposure. The polymorphisms of genes examined include GSTM1, GSTT1, CYP1A1, microsomal epoxide hydrolase (mEH) and excision repair cross-complementary group 2 (ERCC2). A total of 194 subjects with a broad range of PAH exposures were recruited, including 116 occupationally exposed workers, 49 metropolitan residents and 29 suburban gardeners. A significant exposure-response relationship was observed between PAH exposure and DNA adducts in leukocytes across the entire group of subjects (p < 0.0001). The levels of PAH-DNA adducts in the subgroup with lowest occupational exposure to PAHs (< 0.1 microg BaP m(-3)) was significantly higher than that in metropolitan residents and suburban gardeners. However, no significant difference was detected between residents and gardeners, with mean BaP concentrations of 0.028 and 0.011 microg m(-3), respectively. The polymorphisms of genes examined failed to show significant effects on PAH-induced adduct formation except ERCC2 Lys751Gln genotypes. A significantly higher level of PAH-DNA adduct was found in subjects with wild-type ERCC2 than those who have either heterozygous or homozygous variant alleles (p < 0.01). Smoking, age and gender did not substantially contribute to PAH-induced DNA adduct formation in this study. The study suggests that PAH-DNA adducts may serve as a reliable biomarker of PAH exposure in occupational settings but may not be sensitive enough to be used in populations with environmental exposures to PAHs.

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.

National Emphysema Treatment Trial state of the art: genetics of emphysema

Although a hereditary contribution to emphysema has been long suspected, severe alpha1-antitrypsin deficiency remains the only conclusively proven genetic risk factor for chronic obstructive pulmonary disease (COPD). Recently, genome-wide linkage analysis has led to the identification of two promising candidate genes for COPD: TGFB1 and SERPINE2. Like multiple other COPD candidate gene associations, even these positionally identified genes have not been universally replicated across all studies. Differences in phenotype definition may contribute to nonreplication in genetic studies of heterogeneous disorders such as COPD. The use of precisely measured phenotypes, including emphysema quantification on high-resolution chest computed tomography scans, has aided in the discovery of additional genes for clinically relevant COPD-related traits. The use of computed tomography scans to assess emphysema and airway disease as well as newer genetic technologies, including gene expression microarrays and genome-wide association studies, has great potential to detect novel genes affecting COPD susceptibility, severity, and response to treatment.

Aberrant fibrillin-1 expression in early emphysematous human lung: a proposed predisposition for emphysema

Parenchymal destruction, airspace enlargement, and loss of elasticity are hallmarks of pulmonary emphysema. Although the basic mechanism is unknown, there is a consensus that malfunctioning of the extracellular matrix is a major contributor to the pathogenesis of emphysema. In this study, we analyzed the expression of the elastic fiber protein fibrillin-1 in a large number (n=69) of human lung specimens with early-onset emphysema. Specimens were morphologically characterized by the Destructive Index, the Mean Linear Intercept, and the Panel Grading. We observed a strong correlation (P<0.001) of aberrant fibrillin-1 staining with the degree of destruction of lung parenchyma (r=0.71), airspace enlargement (r=0.47), and emphysema-related morphological abnormalities (r=0.69). There were no obvious correlations with age and smoking behavior. Staining for three other extracellular matrix components (type I collagen, type IV collagen, and laminin) was not affected. The aberrant fibrillin-1 staining observed in this study is similar to that observed in Marfan syndrome, a syndrome caused by mutations in the gene encoding fibrillin-1. Strikingly, emphysema is noticed in a number of Marfan patients. This, together with the notion that disruption of the fibrillin-1 gene in mice results in emphysematous lesions, makes fibrillin-1 a strong candidate to be involved in the etiology and pathogenesis of emphysema.

COPD in Asia: where East meets West

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

Genetic polymorphisms of GSTP1 and mEPHX correlate with oxidative stress markers and lung function in COPD

The genetic susceptibility to COPD might depend on variations in detoxification enzymes that activate and detoxify cigarette smoke products, which otherwise generate oxidative stress causing pathogenesis. In a case-control study of 202 COPD patients and 136 normals, we examined the association of polymorphisms I105V, A114V of GSTP1 and Y113H, H139R of mEPHX individually or in combination with disease and their contribution to oxidative stress markers such as MDA, GSH, GPx and airflow obstruction. Patients were over-represented by the alleles 105V, 114V of GSTP1 and 113H, 139H of mEPHX (chi(2)=10.63, p=0.001, chi(2)=13.92, p<0.001, chi(2)=13.02, p<0.001 and chi(2)=4.48, p=0.034, respectively) and the haplotypes of same alleles i.e. 105V-114V and 113H-139H (chi(2)=14.58, p<0.001 and chi(2)=23.14, p<0.001). Moreover, there was marked over-representation of combination of genotypes, I105I+A114A of GSTP1 (53% vs. 36%) in controls; whereas, the combinations with 105V/114V alleles (64% vs. 47%) of GSTP1 (OR=1.99; 95% CI=1.28-3.09; p=0.002) and the homozygotes H113H+H139H (27% vs.10%) of mEPHX (OR=3.26; 95% CI=1.73-6.15; p=0.0001) in patients. Patients had significantly elevated MDA level (p<0.001) and decreased GSH level (p<0.001) and GPx activity (p=0.035), respectively. Of note, the genotypes, I105V/V105V, A114V/V114V of GSTP1 and Y113H/H113H of mEPHX associated with increased MDA level (p=0.04, p=0.03 and p=0.003), decreased GSH level (p=0.019, p=0.007 and p=0.0006) and lower FEV1 (p=0.23, p=0.037 and p=0.029), respectively, in patients; so was the correlation of these biomarkers and lung function with the combinations of the genotypes. In conclusion, 105V/114V alleles of GSTP1 and 113H/139H alleles of mEPHX and the combination of genotypes with same alleles associated with imbalanced oxidative stress and lung function in patients, signifying the importance in the disease.

Genetic determinants of emphysema distribution in the national emphysema treatment trial

RATIONALE

Computed tomography (CT) scanning of the lung may reduce phenotypic heterogeneity in defining subjects with chronic obstructive pulmonary disease (COPD), and allow identification of genetic determinants of emphysema severity and distribution.

OBJECTIVES

We sought to identify genes associated with CT scan distribution of emphysema in individuals without alpha1-antitrypsin deficiency but with severe COPD.

METHODS

We evaluated baseline CT densitometry phenotypes in 282 individuals with emphysema enrolled in the Genetics Ancillary Study of the National Emphysema Treatment Trial, and used regression models to identify genetic variants associated with emphysema distribution.

MEASUREMENTS AND MAIN RESULTS

Emphysema distribution was assessed by two methods--assessment by radiologists and by computerized density mask quantitation, using a threshold of -950 Hounsfield units. A total of 77 polymorphisms in 20 candidate genes were analyzed for association with distribution of emphysema. GSTP1, EPHX1, and MMP1 polymorphisms were associated with the densitometric, apical-predominant distribution of emphysema (p value range = 0.001-0.050). When an apical-predominant phenotype was defined by the radiologist scoring method, GSTP1 and EPHX1 single-nucleotide polymorphisms were found to be significantly associated. In a case-control analysis of COPD susceptibility limited to cases with densitometric upper-lobe-predominant cases, the EPHX1 His139Arg single-nucleotide polymorphism was associated with COPD (p = 0.005).

CONCLUSIONS

Apical and basal emphysematous destruction appears to be influenced by different genes. Polymorphisms in the xenobiotic enzymes, GSTP1 and EPHX1, are associated with apical-predominant emphysema. Altered detoxification of cigarette smoke metabolites may contribute to emphysema distribution, and these findings may lead to further insight into genetic determinants of emphysema.

Genetic analysis of CC16, OGG1 and GCLC polymorphisms and susceptibility to COPD

BACKGROUND AND OBJECTIVES

The importance of genetic susceptibility in COPD has not been determined. The aim of this study was to investigate the association between susceptibility to COPD and polymorphisms in the Clara cell 16 kDa secretory protein (CC16), 8-hydroxy-guanine glycosylase (OGG1) and glutamatecysteine ligase catalytic subunit (GCLC) genes in a southern Chinese population of Han nationality.

METHODS

A case-control study was performed on 166 paired subjects with or without COPD, who were randomly selected from a pool of 310 paired subjects. These subjects were selected from epidemiological survey participants, with matched-pairs being strictly localized in the Guangzhou urban and Shaoguan rural areas. The following polymorphisms were genotyped by PCR-single strand conformation polymorphism analysis: 38 A/G in exon 1 of the CC16 gene, 1245C/G in exon 7 of the OGG1 gene and -129C/T in the GCLC gene. Genotype frequencies and allelic frequencies were analysed.

RESULTS

There were no significant differences in the distribution of genotype frequencies for CC16 38 A/G, OGG1 1245C/G or GCLC -129C/T between the COPD and non-COPD subjects. The distribution of the allelic frequencies of these three genes also showed no significant difference between the two groups.

CONCLUSIONS

The genetic polymorphisms in CC16 38 A/G, OGG1 1245C/G and GCLC -129C/T are not associated with susceptibility to COPD in a southern Chinese population of Han nationality.

Glutathione S-transferase genotypes modify lung function decline in the general population: SAPALDIA cohort study

Background

Understanding the environmental and genetic risk factors of accelerated lung function decline in the general population is a first step in a prevention strategy against the worldwide increasing respiratory pathology of chronic obstructive pulmonary disease (COPD). Deficiency in antioxidative and detoxifying Glutathione S-transferase (GST) gene has been associated with poorer lung function in children, smokers and patients with respiratory diseases. In the present study, we assessed whether low activity variants in GST genes are also associated with accelerated lung function decline in the general adult population.

Methods

We examined with multiple regression analysis the association of polymorphisms in GSTM1, GSTT1 and GSTP1 genes with annual decline in FEV1, FVC, and FEF_25–75 during 11 years of follow-up in 4686 subjects of the prospective SAPALDIA cohort representative of the Swiss general population. Effect modification by smoking, gender, bronchial hyperresponisveness and age was studied.

Results

The associations of GST genotypes with FEV1, FVC, and FEF_25–75 were comparable in direction, but most consistent for FEV1. GSTT1 homozygous gene deletion alone or in combination with GSTM1 homozygous gene deletion was associated with excess decline in FEV1 in men, but not women, irrespective of smoking status. The additional mean annual decline in FEV1 in men with GSTT1 and concurrent GSTM1 gene deletion was -8.3 ml/yr (95% confidence interval: -12.6 to -3.9) relative to men without these gene deletions. The GSTT1 effect on the FEV1 decline comparable to the observed difference in FEV1 decline between never and persistent smoking men. Effect modification by gender was statistically significant.

Conclusion

Our results suggest that genetic GSTT1 deficiency is a prevalent and strong determinant of accelerated lung function decline in the male general population.

Genetics of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a complex disease with multifactorial background, based on the interaction of environmental and genetic factors. Environmental factors are clearly related to the development of the disease. However, family and twin studies suggested genetics factors to be one of the important determinants for the development of COPD. Different approaches have been used to identify genes of interest. Genomewide linkage analysis found areas of interest on different chromosomes, with some genes located in this regions being identified and replicated as susceptibility genes. Numerous of candidate genes that could be linked to disease pathogenesis have been implicated in COPD genetics. However, the candidate gene approach is often limited by inconsistent results in other study populations. Recently, a combination of different methods is used giving more evidence for some candidate genes, including TGFbeta-1, Surfactant, SERPINE2 and microsomal epoxide hydrolase. In the future ongoing exact phenotype definition, combination of several approaches, genome-wide association studies and animal model genetics will lead to new insights into the genetics of COPD, with epigenetic factors needs to be further investigated and considered in concert with genetic findings.

The genetics of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease caused by the interaction of genetic susceptibility and environmental influences. There is increasing evidence that genes link to disease pathogenesis and heterogeneity by causing variation in protease anti-protease systems, defence against oxidative stress and inflammation. The main methods of genomic research for complex disease traits are described, together with the genes implicated in COPD thus far, their roles in disease causation and the future for this area of investigation.

The Association Between Polymorphic Genotypes of Glutathione S-Transferases and COPD in the Turkish Population

Although smoking is regarded as the most important causal factor in chronic obstructive pulmonary disease (COPD), only 10-20% of smokers develop symptomatic COPD, which indicates the presence of genetic predisposing factors in its pathogenesis. This study investigates the association between gene polymorphysims of glutathione S-transferases (GSTs) and COPD. Blood samples were taken from 149 patients and 150 healthy controls. Polymorphisms of GSTT1, GSTM1, and GSTP1 were genotyped using Real-Time PCR. Multivariate logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals between specific genotypes and COPD. There was no difference in the frequencies of the genotypes of GSTM1 and GSTT1 between the groups, but the GSTP1 Ile/Ile genotype was significantly higher in the patients than in the controls (61.1% vs. 38%). GSTP1 Ile/Val and Val/Val genotypes were associated with a decreased risk of COPD when compared to the Ile/Ile genotype (2.12-fold and 4-fold, respectively). Thus we suggest that the Val allele of GSTP1 may have a protective effect for development of COPD. Furthermore, when we evaluated the association between GSTP1 genes and smoking status, smokers with the GSTP1 Ile allele had an increased risk for the development of COPD. Among the combinations of the genotypes, the combination of GSTM1, GSTT1 null, and GSTP1 Val/Val was associated with the maximal increased risk (12-fold) of COPD. Thus to explain the ethiopathogenesis of COPD, investigation of a single gene family is inadequate. Based on our results and the previous data, further studies should be focused on the GSTP1 gene and the interactions with other genes such as polymorphisms of N-acetyltransferases, GSTM1 and GSTT1, microsomal epoxide hydrolase, and allelic variants of cytochrome P450.