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

Association between the oxidative stress gene polymorphism and chronic obstructive pulmonary disease risk: a meta-analysis

BACKGROUND

The association between the oxidative stress gene polymorphism and chronic obstructive pulmonary disease (COPD) risk has been extensively studied but the results have been controversial. This study aimed to investigate the overall association between the oxidative stress gene including glutathione S-transferase (GST), epoxide hydrolase exon (EPHX), superoxide dismutase (SOD), catalase (CAT), cytochrome P450 system (CYP) and heme oxygenase (HO-1) polymorphism and the risk of COPD.

METHODS

We searched the PubMed and EMBASE database to identify studies that investigated the association between the oxidative stress gene polymorphism and risk of COPD. The relevant data were extracted and statistical analyses were performed using the Revman 5.4 and STATA 12 software. Dominant genetic model, recessive model, co-dominant model, heterozygote model, and allele model were analyzed. Venice criteria and publication bias were conducted to access the credibility and reliability.

RESULTS

In total, 63 publications including 14,733 patients and 50,570 controls were included in the meta-analysis.15 genetic variants of 6 genes were analyzed, and 7 SNPs in GSTP1, CAT, CYP, SOD were first analyses until now. In our study, EPHX T113C C allele, GSTM1 null, GSTT1 null, GSTP1 A313G G and C341T T allele, CYP1A1 MspI C allele, SOD3 A213G G allele and L type in Ho-1 showed increased COPD risk, especially in Asians. T allele in CAT C262T and C allele in SOD2 Val 9 Ala were associated with decreased COPD risk. To avoid high heterogeneity and publications bias, subgroups analysis was performed in accord with HWE and ethnicity. Publication bias was assessed by Begg's funnel plots and Egger's test, and no publication bias were found for recessive models. 4 variants were identified with strong levels of epidemiological evidence of associations with the COPD risk.

CONCLUSIONS

Our results confirm that oxidative stress gene polymorphism was associated with COPD risk. These finding can improve human understanding of this disease gene molecular level and enable early intervention and prevention of COPD. Well-designed studies with large sample sizes are essential to clarify the association of these significant variants with the susceptibility to COPD.

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.

Variability in oxidative stress-related genes (SOD2, CAT, GPX1, GSTP1, NOS3, NFE2L2, and UCP2) and susceptibility to migraine clinical phenotypes and features

Introduction

Migraine is a complex disorder with genetic and environmental inputs. Cumulative evidence implicates oxidative stress (OS) in migraine pathophysiology while genetic variability may influence an individuals' oxidative/antioxidant capacity. Aim of the current study was to investigate the impact of eight common OS-related genetic variants [rs4880 (SOD2), rs1001179 (CAT), rs1050450 (GPX1), rs1695 (GSTP1), rs1138272 (GSTP1), rs1799983 (NOS3), rs6721961 (NFE2L2), rs660339 (UCP2)] in migraine susceptibility and clinical features in a South-eastern European Caucasian population.

Methods

Genomic DNA samples from 221 unrelated migraineurs and 265 headache-free controls were genotyped for the selected genetic variants using real-time PCR (melting curve analysis).

Results

Although allelic and genotypic frequency distribution analysis did not support an association between migraine susceptibility and the examined variants in the overall population, subgroup analysis indicated significant correlation between NOS3 rs1799983 and migraine susceptibility in males. Furthermore, significant associations of CAT rs1001179 and GPX1 rs1050450 with disease age-at-onset and migraine attack duration, respectively, were revealed. Lastly, variability in the CAT, GSTP1 and UCP2 genes were associated with sleep/weather changes, alcohol consumption and physical exercise, respectively, as migraine triggers.

Discussion

Hence, the current findings possibly indicate an association of OS-related genetic variants with migraine susceptibility and clinical features, further supporting the involvement of OS and genetic susceptibility in migraine.

Shorter telomere length, higher telomerase activity in association with tankyrase gene polymorphism contribute to high-altitude pulmonary edema

High-altitude pulmonary edema (HAPE) is a noncardiogenic form of pulmonary edema, which is induced upon exposure to hypobaric hypoxia at high altitude (HA). Hypobaric hypoxia generates reactive oxygen species that may damage telomeres and disturb normal physiological processes. Telomere complex comprises of multiple proteins, of which, tankyrase (TNKS) is actively involved in DNA damage repairs. We hence investigated the association of TNKS and telomeres with HAPE to delineate their potential role at HA. The study was performed in three groups, High-altitude pulmonary edema patients (HAPE-p, n = 200), HAPE-resistant sojourners (HAPE-r, n = 200) and highland permanent healthy residents (HLs, n = 200). Variants of TNKS were genotyped using polymerase chain reaction-restriction fragment length polymorphism. Plasma TNKS level was estimated using enzyme-linked immunosorbent assay, expression of TNKS and relative telomere length were assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and telomerase activity was assessed by the telomere repeat amplification protocol assay. TNKS poly-ADP ribosylates the telomere-repeat factor (TRF), which is a negative regulator of telomere length. Consequently, TRF expression was also measured by RT-qPCR. The TNKS heterozygotes rs7015700GA were prevalent in HLs compared to the HAPE-p and HAPE-r. The plasma TNKS was significantly decreased in HAPE-p than HAPE-r (P = 0.006). TNKS was upregulated 9.27 folds in HAPE-p (P = 1.01E-06) and downregulated in HLs by 3.3 folds (P = 0.02). The telomere length was shorter in HAPE-p compared to HAPE-r (P = 0.03) and HLs (P = 4.25E-4). The telomerase activity was significantly higher in HAPE-p compared to both HAPE-r (P = 0.01) and HLs (P = 0.001). HAPE-p had the lowest TNKS levels (0.186 ± 0.031 ng/μl) and the highest telomerase activity (0.0268 amoles/μl). The findings of the study indicate the association of TNKS and telomeres with HA adaptation/maladaptation.

Seeding drug discovery: Telomeric tankyrase as a pharmacological target for the pathophysiology of high-altitude hypoxia

Cellular exposure to extreme environments leads to the expression of multiple proteins that participate in pathophysiological manifestations. Hypobaric hypoxia at high altitude (HA) generates reactive oxygen species (ROS) that can damage telomeres. Tankyrase (TNKS) belongs to multiple telomeric protein complexes and is actively involved in DNA damage repair. Although published research on TNKS indicates its possible role in cancer and other hypoxic diseases, its role in HA sicknesses remains elusive. Understanding the roles of telomeres, telomerase, and TNKS could ameliorate physiological issues experienced at HA. In addition, telomeric TNKS could be a potential biomarker in hypoxia-induced sicknesses or acclimatization. Thus, a new research avenue on TNKS linked to HA sickness might lead to the discovery of drugs for hypobaric hypoxia.

Applying whole-genome sequencing in relation to phenotype and outcomes in siblings with cystic fibrosis

Variations in disease onset and/or severity have often been observed in siblings with cystic fibrosis (CF), despite the same CFTR genotype and environment. We postulated that genomic variation (modifier and/or pharmacogenomic variants) might explain these clinical discordances. From a cohort of patients included in the Wisconsin randomized clinical trial (RCT) of newborn screening (NBS) for CF, we identified two brothers who showed discordant lung disease courses as children, with one milder and the other more severe than average, and a third, eldest brother, who also has severe lung disease. Leukocytes were harvested as the source of DNA, and whole-genome sequencing (WGS) was performed. Variants were identified and analyzed using in-house-developed informatics tools. Lung disease onset and severity were quantitatively different between brothers during childhood. The youngest, less severely affected brother is homozygous for HFE p.H63D. He also has a very rare PLG p.D238N variant that may influence host-pathogen interaction during chronic lung infection. Other variants of interest were found differentially between the siblings. Pharmacogenomics findings were consistent with the middle, most severely affected brother having poor outcomes to common CF treatments. We conclude that genomic variation between siblings with CF is expected. Variable lung disease severity may be associated with differences acting as genetic modifiers and/or pharmacogenomic factors, but large cohort studies are needed to assess this hypothesis.

Glutathione S-transferase genes and the risk of type 2 diabetes mellitus: Role of sexual dimorphism, gene-gene and gene-smoking interactions in disease susceptibility

BACKGROUND

Compromised defense against reactive oxygen species (ROS) is considered important in the pathogenesis of type 2 diabetes mellitus (T2DM); therefore, genes encoding antioxidant defense enzymes may contribute to disease susceptibility. This study investigated whether polymorphisms in genes encoding glutathione S-transferase M1 (GSTM1), T1 (GSTT1), and P1 (GSTP1) jointly contribute to the risk of T2DM.

METHODS

In all, 1120 unrelated Russian subjects (600 T2DM patients, 520 age- and sex-matched healthy subjects), were recruited to the study. Genotyping was performed by multiplex polymerase chain reaction (PCR; del/del polymorphisms of GSTM1 and GSTT1) and TaqMan-based PCR (polymorphisms I105V and A114V of GSTP1). Plasma ROS and glutathione levels in study subjects were analyzed by fluorometric and colorimetric assays, respectively.

RESULTS

Genotype del/del GSTT1 was significantly associated with the risk of T2DM (odds ratio [OR] 1.60, 95% confidence interval [CI] 1.17-2.21, P = 0.003). Gender-stratified analysis showed that the deletion genotypes of GSTM1 (OR 1.99, 95% CI 1.30-3.05; P = 0.0002, Q = 0.016) and GSTT1 (OR 2.23, 95% CI 1.22-4.09; P = 0.008, Q = 0.0216), as well as genotype 114A/V of GSTP1 (OR 2.85, 95% CI 1.44-5.62; P = 0.005, Q = 0.02) were associated with an increased risk of T2DM exclusively in males. Three genotype combinations (i.e. GSTM1+ × GSTT1+, GSTM1+ × GSTP1 114A/A and GSTT1+ × GSTP1 114A/A) showed significant associations with a decreased risk of T2DM in males.

CONCLUSIONS

This study demonstrates, for the first time, that genes encoding glutathione S-transferases jointly contribute to the risk of T2DM, and that their effects on disease susceptibility are gender specific.

Glutathione-S-transferase P1 may predispose children to a decline in pulmonary function after stem cell transplant

RATIONALE

Pulmonary complications after hematopoietic stem cell transplant (SCT) are associated with increased mortality. Genetic markers for those at risk for pulmonary impairment post-SCT have not been widely investigated.

METHODS

Forty-nine patients were retrospectively selected from a single institution's biorepository with linked clinical data. All subjects performed pre-SCT PFTs. Genotyping was conducted using the Infinium Exome-24 BeadChip. Four single nucleotide polymorphisms (SNPs) were selected (rs1800871, rs1695, rs1800629, rs12477314) and evaluated for association with PFT parameters as change over time from baseline. Associations between SNPs and PFT parameters were assessed and adjusted for the following confounding variables: age, gender, and race.

RESULTS

Using the recessive genetic model, patients with one or two minor alleles for the glutathione S-transferase P1 (GSTP1) SNP rs1695 had a lower decline in FEV₁ and FEF_25-75 at 1-year post-SCT compared to patients who were homozygous for the ancestral allele (adjusted P-values <0.01 and 0.02, respectively). No other SNPs were significantly associated with other PFT parameters.

CONCLUSIONS

Our findings suggest that GSTP1 genotype may be associated with lung function during the first year post-SCT. Identifying and investigating genes that predispose patients to pulmonary complications after SCT may allow for more personalized patient management based on pre-emptive genetic testing. The glutathione S-transferase gene merits further investigation.

In silico search for modifier genes associated with pancreatic and liver disease in Cystic Fibrosis

Cystic Fibrosis is the most common lethal autosomal recessive disorder in the white population, affecting among other organs, the lung, the pancreas and the liver. Whereas Cystic Fibrosis is a monogenic disease, many studies reveal a very complex relationship between genotype and clinical phenotype. Indeed, the broad phenotypic spectrum observed in Cystic Fibrosis is far from being explained by obvious genotype-phenotype correlations and it is admitted that Cystic Fibrosis disease is the result of multiple factors, including effects of the environment as well as modifier genes. Our objective was to highlight new modifier genes with potential implications in the lung, pancreatic and liver outcomes of the disease. For this purpose we performed a system biology approach which combined, database mining, literature mining, gene expression study and network analysis as well as pathway enrichment analysis and protein-protein interactions. We found that IFI16, CCNE2 and IGFBP2 are potential modifiers in the altered lung function in Cystic Fibrosis. We also found that EPHX1, HLA-DQA1, HLA-DQB1, DSP and SLC33A1, GPNMB, NCF2, RASGRP1, LGALS3 and PTPN13, are potential modifiers in pancreas and liver, respectively. Associated pathways indicate that immune system is likely involved and that Ubiquitin C is probably a central node, linking Cystic Fibrosis to liver and pancreatic disease. We highlight here new modifier genes with potential implications in Cystic Fibrosis. Nevertheless, our in silico analysis requires functional analysis to give our results a physiological relevance.

Exploring the interaction among EPHX1, GSTP1, SERPINE2, and TGFB1 contributing to the quantitative traits of chronic obstructive pulmonary disease in Chinese Han population

Background

Currently, the majority of genetic association studies on chronic obstructive pulmonary disease (COPD) risk focused on identifying the individual effects of single nucleotide polymorphisms (SNPs) as well as their interaction effects on the disease. However, conventional genetic studies often use binary disease status as the primary phenotype, but for COPD, many quantitative traits have the potential correlation with the disease status and closely reflect pathological changes.

Method

Here, we genotyped 44 SNPs from four genes (EPHX1, GSTP1, SERPINE2, and TGFB1) in 310 patients and 203 controls which belonged to the Chinese Han population to test the two-way and three-way genetic interactions with COPD-related quantitative traits using recently developed generalized multifactor dimensionality reduction (GMDR) and quantitative multifactor dimensionality reduction (QMDR) algorithms.

Results

Based on the 310 patients and the whole samples of 513 subjects, the best gene-gene interactions models were detected for four lung-function-related quantitative traits. For the forced expiratory volume in 1 s (FEV1), the best interaction was seen from EPHX1, SERPINE2, and GSTP1. For FEV₁%pre, the forced vital capacity (FVC), and FEV₁/FVC, the best interactions were seen from SERPINE2 and TGFB1.

Conclusion

The results of this study provide further evidence for the genotype combinations at risk of developing COPD in Chinese Han population and improve the understanding on the genetic etiology of COPD and COPD-related quantitative traits.

Electronic supplementary material

The online version of this article (doi:10.1186/s40246-016-0076-0) contains supplementary material, which is available to authorized users.

Modification of the association of bisphenol A with abnormal liver function by polymorphisms of oxidative stress-related genes

Some studies suggested oxidative stress as a possible mechanism for the relation between exposure to bisphenol A (BPA) and liver damage. Therefore, we evaluated modification of genetic polymorphisms of cyclooxygenase 2 (COX2 or PTGS2), epoxide hydrolase 1 (EPHX1), catalase (CAT), and superoxide dismutase 2 (SOD2 or MnSOD), which are oxidative stress-related genes, on the relation between exposure to BPA and liver function in the elderly. We assessed the association of visit-to-visit variations in BPA exposure with abnormal liver function by each genotype or haplotype after controlling for age, sex, BMI, alcohol consumption, exercise, urinary cotinine levels, and low density lipoprotein cholesterol using a GLIMMIX model. A significant association of BPA with abnormal liver function was observed only in participants with COX2 GG genotype at rs5277 (odds ratio (OR)=3.04 and p=0.0231), CAT genotype at rs769218 (OR=4.16 and p=0.0356), CAT CT genotype at rs769217 (OR=4.19 and p=0.0348), SOD2 TT genotype at rs4880 (OR=2.59 and p=0.0438), or SOD2 GG genotype at rs2758331 (OR=2.57 and p=0.0457). Moreover, we also found higher OR values in participants with a pair of G-G haplotypes for COX2 (OR=2.81 and p=0.0384), G-C-A haplotype for EPHX1 (OR=4.63 and p=0.0654), A-T haplotype for CAT (OR=4.48 and p=0.0245), or T-G-A haplotype for SOD2 (OR=2.91 and p=0.0491) compared with those with the other pair of haplotypes for each gene. Furthermore, the risk score composed of 4 risky pair of haplotypes showed interactive effect with BPA on abnormal liver function (p=0.0057). Our study results suggest that genetic polymorphisms of COX2, EPHX1, CAT, and SOD2 modify the association of BPA with liver function.

A bioinformatics strategy for detecting the complexity of Chronic Obstructive Pulmonary Disease in Northern Chinese Han Population

Chronic Obstructive Pulmonary Disease (COPD) is a complex human disease which is driven not only by genetic factors, but also by various environmental variables, such as gender, age and smoking. Therefore, there is a demand for investigating the complexity among various risk factors involved in COPD. In this study, 44 tagging SNPs from EPHX1, GSTP1, SERPINE2 and TGFB1 were selected and genotyped in 310 COPD cases and 203 controls, all of which belong to the Han from North China. We integrated functional prediction algorithms of nonsynonymous SNPs (nsSNPs) into Bayesian network to explore the complex regulatory relationships among disease traits and various risk factors. The results showed that three basic variables (age, sex and smoking) were risk factors of COPD-related trait and phenotype. Besides these environmental risk factors, deleterious nsSNPs were found to perform better than those of significant synonymous SNPs when used as variables to make risk prediction of disease outcome. This study provides further evidences for detecting the complexity of COPD in Northern Chinese Han Population.

Association between glutathione S-transferase P1 Ile (105) Val gene polymorphism and chronic obstructive pulmonary disease: A meta-analysis based on seventeen case-control studies

INTRODUCTION

Previous studies have shown that glutathione S-transferase P1 (GSTP1) was associated with chronic obstructive pulmonary disease (COPD). However, the association between GSTP1 Ile (105) Val gene polymorphism and COPD remains controversial. To drive a more precise estimation, we performed a meta-analysis based on published case-control studies.

METHODS

An electronic search of PubMed, EMBASE, Cochrane library, Web of Science and China Knowledge Resource Integrated (CNKI) Database for papers on GSTP1 Ile (105) Val gene polymorphism and COPD risk was performed. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association in the homozygote model, heterozygote model, dominant model, recessive model and an additive mode. Statistical heterogeneity, test of publication bias and sensitivity analysis was performed. The software STATA (Version 13.0) was used data analysis.

RESULTS

Overall, seventeen studies with 1892 cases and 2012 controls were included in this meta-analysis. The GSTP1 Ile (105) Val polymorphism showed pooled odds ratios for the homozygote comparison (OR = 1.501, 95%CI [0.862, 2.614]), heterozygote comparison (OR = 0.924, 95%CI [0.733, 1.165]), dominant model (OR = 1.003, 95%CI [0.756, 1.331]), recessive model (OR = 1.510, 95%CI [0.934, 2.439]), and an additive model (OR = 1.072, 95%CI [0.822, 1.398]).

CONCLUSIONS

In conclusion, the current meta-analysis, based on the most updated information, showed no significant association between GSTP1 Ile (105) Val gene polymorphism and COPD risk in any genetic models. The results of subgroup analysis also showed no significant association between GSTP1 Ile (105) Val gene polymorphism and COPD risk in Asian population and Caucasian population. Further studies involving large populations and careful control with age, sex, ethnicity, and cigarette smoking are greatly needed.

Paraoxonase-1 gene in patients with chronic obstructive pulmonary disease investigation Q192R and L55M polymorphisms

BACKGROUND

The effect of increased oxidative stress on the development of chronic obstructive pulmonary disease (COPD) is well known. One of the antioxidative systems against oxidative stress in human body is paraoxonase (PON) enzyme that protects low density lipoproteins (LDL) against oxidation. This study aimed to explore the polymorphisms on PON1, Q192R, L55M genes of patients with COPD.

METHODS

DNAs extraction was obtained from blood samples of 50 patients diagnosed with COPD and 50 patients as a control group who were presented to emergency clinic. Genotypes were obtained with polymerase chain reaction (PCR) and AIw I and Hsp92II restriction enzymes were used for Q192R and L55M polymorphisms, respectively. Analysis of data was done with the Chi-square test and Fisher's exact test.

RESULTS

A statistically significant difference in Q192R polymorphism was found between the COPD patients and the control group (P=0.05). There was no statistically significant difference in L55M polymorphisms between the patient and control groups (P>0.05). Q192R polymorphism was significantly correlated with the PON1 gene and cigarette smoking; however other risk factors did not show any significant correlation with this polymorphism. Though L55M polymorphism was significantly correlated with family history and tuberculosis, there was no significant correlation with other risk factors.

CONCLUSION

We believe that more studies are needed to study the correlation of L55M polymorphism with other factors.

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.

The role of epoxide hydrolases in health and disease

Epoxide hydrolases (EH) are ubiquitously expressed in all living organisms and in almost all organs and tissues. They are mainly subdivided into microsomal and soluble EH and catalyze the hydration of epoxides, three-membered-cyclic ethers, to their corresponding dihydrodiols. Owning to the high chemical reactivity of xenobiotic epoxides, microsomal EH is considered protective enzyme against mutagenic and carcinogenic initiation. Nevertheless, several endogenously produced epoxides of fatty acids function as important regulatory mediators. By mediating the formation of cytotoxic dihydrodiol fatty acids on the expense of cytoprotective epoxides of fatty acids, soluble EH is considered to have cytotoxic activity. Indeed, the attenuation of microsomal EH, achieved by chemical inhibitors or preexists due to specific genetic polymorphisms, is linked to the aggravation of the toxicity of xenobiotics, as well as the risk of cancer and inflammatory diseases, whereas soluble EH inhibition has been emerged as a promising intervention against several diseases, most importantly cardiovascular, lung and metabolic diseases. However, there is reportedly a significant overlap in substrate selectivity between microsomal and soluble EH. In addition, microsomal and soluble EH were found to have the same catalytic triad and identical molecular mechanism. Consequently, the physiological functions of microsomal and soluble EH are also overlapped. Thus, studying the biological effects of microsomal or soluble EH alterations needs to include the effects on both the metabolism of reactive metabolites, as well as epoxides of fatty acids. This review focuses on the multifaceted role of EH in the metabolism of xenobiotic and endogenous epoxides and the impact of EH modulations.

Genetic determinants of chronic obstructive pulmonary disease in South Indian male smokers

The development of chronic obstructive pulmonary disease, upon exposure to tobacco smoke, is the cumulative effect of defects in several genes. With the aim of understanding the genetic structure that is characteristic of our patient population, we selected forty two single nucleotide polymorphisms of twenty genes based on previous studies and genotyped a total of 382 samples, which included 236 patients and 146 controls using Sequenom MassARRAY system. Allele frequencies of rs2276109 (MMP12) and rs1800925 (IL13) differed significantly between patients and controls (p = 0.013 and 0.044 respectively). Genotype analysis showed association of rs2276109 (MMP12) under additive and dominant models (p = 0.017, p = 0.012 respectively), rs1800925 (IL13) under additive model (p = 0.047) and under recessive model, rs1695 (GSTP1; p = 0.034), rs729631, rs975278, rs7583463 (SERPINE2; p = 0.024, 0.024 and 0.012 respectively), rs2568494, rs10851906 (IREB2; p = 0.026 and 0.041 respectively) and rs7671167 (FAM13A; p = 0.029). The minor alleles of rs1695 (G), rs7671167 (T), rs729631 (G), rs975278 (A) and rs7583463 (A) showed significant negative association whereas those of rs2276109 (G), rs2568494 (A), rs10851906 (G) and rs1800469 (T; TGF-β) showed significant positive association with lung function under different genetic models. Haplotypes carrying A allele of rs2276109, G allele of rs1695 showed negative correlation with lung function. Haplotypes carrying major alleles of rs7671167 (C) of FAM13A and rs729631 (C), rs975278 (G), rs7583463 (C) of SERPINE2 had protective effect on lung function. Haplotypes of IREB2 carrying major alleles of rs2568494 (G), rs2656069 (A), rs10851906 (A), rs965604 (C) and minor alleles of rs1964678 (T), rs12593229 (T) showed negative correlation with lung function. In conclusion, our study replicated the results of most of the previous studies. However, the positive correlation between the minor alleles of rs2568494 (A) and rs10851906 (G) of IREB2 and lung function needs further investigation.

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.

Evaluation of glutathione S-transferase P1 polymorphisms (Ile105Val and Ala114Val) in patients with small cell lung cancer

AIMS

Glutathione S-transferase P1 (GSTP1) plays an important role in cellular protection against oxidative stress and toxic chemicals. Polymorphisms within GSTP1 are associated with alterations in enzyme activity, which may lead to development of lung disease and cancer. In this study, we aimed to investigate the GSTP1 Ile105Val and Ala114Val polymorphisms in patients with small cell lung cancer (SCLC).

PATIENTS/METHODS

GSTP1 Ile105Val polymorphism in exon 5 and GSTP1 Ala114Val polymorphism in exon 6 were determined by using polymerase chain reaction-restriction fragment length polymorphism techniques in 89 patients with SCLC and 108 control patients with chronic obstructive pulmonary disease (COPD). Genotype frequencies and cigarette smoking intensities were compared among SCLC and COPD patients.

RESULTS

There were significantly less SCLC patients with variant exon 6 genotypes than COPD patients (7.9% vs. 20.4%, p=0.007), while the number of patients with variant exon 5 genotypes were comparable among groups. SCLC and COPD patients with variant exon 6 genotype showed trends toward exhibiting reduced cigarette consumption.

CONCLUSIONS

The variant GSTP1 exon 6 genotype might be conferring protection against SCLC development. Whether this effect is associated with exposure to cigarette smoking needs to be clarified.

CYBA and GSTP1 variants associate with oxidative stress under hypobaric hypoxia as observed in high-altitude pulmonary oedema

HAPE (high-altitude pulmonary oedema) is characterized by pulmonary hypertension, vasoconstriction and an imbalance in oxygen-sensing redox switches. Excess ROS (reactive oxygen species) contribute to endothelial damage under hypobaric hypoxia, hence the oxidative-stress-related genes CYBA (cytochrome b-245 α polypeptide) and GSTP1 (glutathione transferase Pi 1) are potential candidate genes for HAPE. In the present study, we investigated the polymorphisms -930A/G and H72Y (C/T) of CYBA and I105V (A/G) and A114V (C/T) of GSTP1, individually and in combination, in 150 HAPE-p (HAPE patients), 180 HAPE-r (HAPE-resistant lowland natives) and 180 HLs (healthy highland natives). 8-Iso-PGF2α (8-iso-prostaglandin F2α) levels were determined in plasma and were correlated with individual alleles, genotype, haplotype and gene-gene interactions. The relative expression of CYBA and GSTP1 were determined in peripheral blood leucocytes. The genotype distribution of -930A/G, H72Y (C/T) and I105V (A/G) differed significantly in HAPE-p compared with HAPE-r and HLs (P≤0.01). The haplotypes G-C of -930A/G and H72Y (C/T) in CYBA and G-C and G-T of I105V (A/G) and A114V (C/T) in GSTP1 were over-represented in HAPE-p; in contrast, haplotypes A-T of -930A/G and H72Y (C/T) in CYBA and A-C of I105V (A/G) and A114V (C/T) in GSTP1 were over-represented in HAPE-r and HLs. 8-Iso-PGF2α levels were significantly higher in HAPE-p and in HLs than in HAPE-r (P=2.2×10(-16) and 1.2×10(-14) respectively) and the expression of CYBA and GSTP1 varied differentially (P<0.05). Regression analysis showed that the risk alleles G, C, G and T of -930A/G, H72Y (C/T), I105V (A/G) and A114V (C/T) were associated with increased 8-iso-PGF2α levels (P<0.05). Interaction between the two genes revealed over-representation of most of the risk-allele-associated genotype combinations in HAPE-p and protective-allele-associated genotype combinations in HLs. In conclusion, the risk alleles of CYBA and GSTP1, their haplotypes and gene-gene interactions are associated with imbalanced oxidative stress and, thereby, with high-altitude adaptation and mal-adaptation.

Significance of bioinformatics in research of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is an inflammatory disease characterized by the progressive deterioration of pulmonary function and increasing airway obstruction, with high morality all over the world. The advent of high-throughput omics techniques provided an opportunity to gain insights into disease pathogenesis and process which contribute to the heterogeneity, and find target-specific and disease-specific therapies. As an interdispline, bioinformatics supplied vital information on integrative understanding of COPD. This review focused on application of bioinformatics in COPD study, including biomarkers searching and systems biology. We also presented the requirements and challenges in implementing bioinformatics to COPD research and interpreted these results as clinical physicians.

Air pollution and airway disease

Epidemiological and toxicological research continues to support a link between urban air pollution and an increased incidence and/or severity of airway disease. Detrimental effects of ozone (O(3)), nitrogen dioxide (NO(2)) and particulate matter (PM), as well as traffic-related pollution as a whole, on respiratory symptoms and function are well documented. Not only do we have strong epidemiological evidence of a relationship between air pollution and exacerbation of asthma and respiratory morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD), but recent studies, particularly in urban areas, have suggested a role for pollutants in the development of both asthma and COPD. Similarly, while prevalence and severity of atopic conditions appear to be more common in urban compared with rural communities, evidence is emerging that traffic-related pollutants may contribute to the development of allergy. Furthermore, numerous epidemiological and experimental studies suggest an association between exposure to NO(2) , O(3) , PM and combustion products of biomass fuels and an increased susceptibility to and morbidity from respiratory infection. Given the considerable contribution that traffic emissions make to urban air pollution researchers have sought to characterize the relative toxicity of traffic-related PM pollutants. Recent advances in mechanisms implicated in the association of air pollutants and airway disease include epigenetic alteration of genes by combustion-related pollutants and how polymorphisms in genes involved in antioxidant pathways and airway inflammation can modify responses to air pollution exposures. Other interesting epidemiological observations related to increased host susceptibility include a possible link between chronic PM exposure during childhood and vulnerability to COPD in adulthood, and that infants subjected to higher prenatal levels of air pollution may be at greater risk of developing respiratory conditions. While the characterization of pollutant components and sources promise to guide pollution control strategies, the identification of susceptible subpopulations will be necessary if targeted therapy/prevention of pollution-induced respiratory diseases is to be developed.

Genetic polymorphism in metabolism and host defense enzymes: implications for human health risk assessment

Genetic polymorphisms in xenobiotic metabolizing enzymes can have profound influence on enzyme function, with implications for chemical clearance and internal dose. The effects of polymorphisms have been evaluated for certain therapeutic drugs but there has been relatively little investigation with environmental toxicants. Polymorphisms can also affect the function of host defense mechanisms and thus modify the pharmacodynamic response. This review and analysis explores the feasibility of using polymorphism data in human health risk assessment for four enzymes, two involved in conjugation (uridine diphosphoglucuronosyltransferases [UGTs], sulfotransferases [SULTs]), and two involved in detoxification (microsomal epoxide hydrolase [EPHX1], NADPH quinone oxidoreductase I [NQO1]). This set of evaluations complements our previous analyses with oxidative and conjugating enzymes. Of the numerous UGT and SULT enzymes, the greatest likelihood for polymorphism effect on conjugation function are for SULT1A1 (*2 polymorphism), UGT1A1 (*6, *7, *28 polymorphisms), UGT1A7 (*3 polymorphism), UGT2B15 (*2 polymorphism), and UGT2B17 (null polymorphism). The null polymorphism in NQO1 has the potential to impair host defense. These highlighted polymorphisms are of sufficient frequency to be prioritized for consideration in chemical risk assessments. In contrast, SNPs in EPHX1 are not sufficiently influential or defined for inclusion in risk models. The current analysis is an important first step in bringing the highlighted polymorphisms into a physiologically based pharmacokinetic (PBPK) modeling framework.

Correlation of EPHX1, GSTP1, GSTM1, and GSTT1 genetic polymorphisms with antioxidative stress markers in chronic obstructive pulmonary disease

This study was undertaken to ascertain if a relationship existed between oxidative status and polymorphisms of microsomal epoxide hydrolase X1 (EPHX1), glutathione S-transferase P1 (GSTP1), GSTM1, and GSTT1 in chronic obstructive pulmonary disease (COPD). Erythrocyte glutathione peroxidase (GSH-px), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), and plasma GST activities and total antioxidant status (TAS) as antioxidative stress markers were determined and compared either with individual and combined genotypes of EPHX1 exon 3, GSTP1 exon 5, GSTM1, and GSTT1 polymorphisms in COPD patients and healthy controls from the central area of Tunisia. Statistical data processing revealed significantly lower GSH-px, GR, SOD, CAT, GST, and TAS values in COPD patients in comparison to the control group (P < .001). As for genotypes, there was a no significant association in each of the 6 parameters and individual genotypes (P > .05). A significant correlation between the studied parameters and combined null GSTM1/null GSTT1 (GSH-px: P < .001, GR: P = .026, CAT: P = .018, GST: P = .022, TAS: P = .046), His113His EPHX1/null GSTM1 (GSH-px: P = .001, GST: P = .0012, TAS: P = .013), His113His EPHX1/Val105Val GSTP1 (GSH-px: P = .048, CAT: P = .026, GST: P = .031), and null GSTM1/Val105Val GSTP1 (GSH-px: P = .011, GR: P = .0028, GST: P = .0054, TAS: P = .032) was found in patients. In conclusion, combined genetic polymorphisms of GSTM1, GSTT1, GSTP1, and EPHX1 may have favorable effects on redox balance in COPD patients.

CYP1A1, CYP1A2 and CYBA gene polymorphisms associated with oxidative stress in COPD

BACKGROUND

The genetic susceptibility to chronic obstructive pulmonary disease (COPD) depends on detoxification and antioxidant enzymes, which detoxify cigarette smoke reactive components that, otherwise, generate oxidative stress.

METHODS

In a case-control study of 346 subjects with and without COPD, we examined the polymorphisms 462Ile/Val, 3801T/C of CYP1A1, -3860G/A of CYP1A2 and -930A/G, 242C/T of CYBA individually or in combination and their contribution to oxidative stress markers by measuring malondialdehyde (MDA), catalase (CAT), glutathione (GSH) and glutathione peroxidase (GPx).

RESULTS

COPD patients had significantly increased MDA concentration (p<0.001) and decreased CAT activity, GSH concentration, GPx activity (p< or =0.01). The patients were over-represented by the alleles 462Val, 3801C of CYP1A1 and -930G, 242C of CYBA (p<0.001, p=0.003, p=0.030 and p=0.031, respectively) and consequently the haplotypes of same alleles i.e. 462Val:3801C, 462Val:3801T and -930G:242C (p=0.048, p=0.016 and p=0.039, respectively). Similarly, CYP1A1 and CYP1A2 haplotypes, 462Val:3860G and 462Val:3801T:3860G were significantly over-represented (p=0.001 and p=0.003), respectively in patients. The same alleles-associated genotype-combinations between genes were more prevalent in patients. Of note, the genotypes, 462Ile/Val+Val/Val, 3801TC+CC of CYP1A1 and -930AG+GG of CYBA associated with increased MDA concentration (p=0.018, p=0.045 and p=0.017, respectively), decreased CAT activity (p<0.0001, p=0.080 and p<0.0001, respectively) and GSH concentration (p<0.0001, p=0.0002 and p=0.011, respectively) in patients.

CONCLUSION

The identified alleles, its haplotypes and the genotype-combination along with increased oxidative stress, signify the importance in susceptibility to COPD.

Meta-analyses on suspected chronic obstructive pulmonary disease genes: a summary of 20 years' research

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a complex disorder with high mortality worldwide. Studies on the role of candidate genes and their polymorphisms in COPD development have so far produced ambiguous results.

OBJECTIVES

The aim of this study was to reveal the role of COPD candidate genes using data collected in previous research.

METHODS

We performed meta-analyses on 20 polymorphisms in 12 genes, after searching the PubMed and Embase databases for publications on COPD. These genes involve three main pathways associated with COPD development: the inflammatory, protease-antiprotease balance, and antioxidant pathways.

MEASUREMENTS AND MAIN RESULTS

We obtained significant results for three TGFB1 polymorphisms, although these were based only on a few studies. The IL1RN VNTR polymorphism increases the risk for COPD (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.09-2.65), whereas the TNFA -308 G/A polymorphism does so only in Asian populations (OR, 2.01; 95% CI, 1.21-3.31). The GSTP1 I105V polymorphism was protective for COPD in Asian populations only (OR, 0.69; 95% CI, 0.56-0.85).

CONCLUSIONS

These results demonstrate the importance of ethnicity in identifying specific COPD genes.

Lung function in relation to 2-thiothiazolidine-4-carboxylic acid and genetic effect modification among rubber workers in Sweden

OBJECTIVE

What is the risk of impaired lung function in contemporary Swedish rubber workers and are there modifying effects of genetic variants?

METHODS

Included in the study were 159 rubber exposed and 118 not-rubber exposed workers. Lung function was analyzed as forced vital capacity percent of predicted and forced expiratory volume in 1 second percent of predicted. Levels of 2-thiothiazolidine-4-carboxylic acid (a marker of carbon disulfide and vulcanization fumes) was assessed with liquid chromatography tandem mass spectrometry. Polymorphisms in glutathione-related genes were analyzed by Taqman-based allelic discrimination and ordinary polymerase chain reaction.

RESULTS

There was an association between increasing levels of 2-thiothiazolidine-4-carboxylic acid and impaired lung function among exposed workers. The association was modified by glutathione S-transferase alpha 1 (GSTA1)-52 and GSTP1-114. GSTM1 had an influence on lung function among unexposed workers.

CONCLUSIONS

There may be a risk of impaired lung function in contemporary rubber workers. Gene-modifying effects may be considered in risk assessments.

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.

Genetic variation and gene expression in antioxidant related enzymes and risk of COPD: a systematic review

BACKGROUND

Observational epidemiological studies of dietary antioxidant intake, serum antioxidant concentration and lung outcomes suggest that lower levels of antioxidant defences are associated with decreased lung function. Another approach to understanding the role of oxidant/antioxidant imbalance in the risk of chronic obstructive pulmonary disease (COPD) is to investigate the role of genetic variation in antioxidant enzymes, and indeed family based studies suggest a heritable component to lung disease. Many studies of the genes encoding antioxidant enzymes have considered COPD or COPD related outcomes, and a systematic review is needed to summarise the evidence to date, and to provide insights for further research.

METHODS

Genetic association studies of antioxidant enzymes and COPD/COPD related traits, and comparative gene expression studies with disease or smoking as the exposure were systematically identified and reviewed. Antioxidant enzymes considered included enzymes involved in glutathione metabolism, in the thioredoxin system, superoxide dismutases (SOD) and catalase.

RESULTS

A total of 29 genetic association and 15 comparative gene expression studies met the inclusion criteria. The strongest and most consistent effects were in the genes GCL, GSTM1, GSTP1 and SOD3. This review also highlights the lack of studies for genes of interest, particularly GSR, GGT and those related to TXN. There were limited opportunities to evaluate the contribution of a gene to disease risk through synthesis of results from different study designs, as the majority of studies considered either association of sequence variants with disease or effect of disease on gene expression.

CONCLUSION

Network driven approaches that consider potential interaction between and among genes, smoke exposure and antioxidant intake are needed to fully characterise the role of oxidant/antioxidant balance in pathogenesis.

Radical generation and alterations of erythrocyte integrity as bioindicators of diagnostic or prognostic value in COPD?

Chronic obstructive pulmonary disease (COPD) has recently been viewed as an inflammation-dependent systemic disease. Oxidative modifications in the pulmonary microenvironment can result in a number of functional changes in pulmonary tissue as well as in the blood. Studies have been carried out to detect whether oxidatively modified molecules or cells could be considered possible markers of the disease. We hypothesize here that new insights into COPD could come from enzymes involved in deliberate radical generation (i.e., Nox and NOS family enzymes) as well as from alterations of erythrocyte integrity and function, which could become bioindicators of diagnostic or prognostic value in the near future.

Influence of glutathione-related genes on symptoms and immunologic markers among vulcanization workers in the southern Sweden rubber industries

OBJECTIVE

The aim was to elucidate the role of genetic variants on symptoms of the eyes and airways, headache and nausea, as well as on immunologic markers, among vulcanization workers in the contemporary Swedish rubber industry. Polymorphisms in genes, which are involved in the defense against reactive oxygen species and metabolism of toxic substances present in the vulcanization fumes, were analyzed.

METHODS

One hundred and forty-five exposed and 117 unexposed workers were included in the study. Medical and occupational histories were obtained in structured interviews. Symptoms were recorded and immunologic markers analyzed in blood. Polymorphisms in glutathione-related genes (glutamate cysteine ligase catalytic subunit (GCLC)-129, glutamate cysteine ligase modifier subunit (GCLM)-588, glutathione S-transferase alpha 1 (GSTA1)-52, GSTM1*O, GSTP1-105, GSTP1-114, and GSTT1*O) were analyzed by Taqman-based allelic discrimination and ordinary PCR.

RESULTS

A protective effect of GSTA1-52 (G/A + A/A) genotype on symptoms and immunologic cells, in particular among exposed workers, was suggested. Exposed workers with GSTT1*O had increased risk of nosebleed compared to exposed workers with GSTT1*1. Exposed workers with GSTP1-105 (ile/val + val/val) had decreased levels of total immunoglobulin E (IgE) compared to exposed workers with GSTP1-105 ile/ile. GCLC-129 variant genotype demonstrated increased levels of immunologic cells among exposed workers, although statistical significance was not reached.

CONCLUSION

Our data indicate that hereditary factors influence the susceptibility to symptoms and the immunologic response of workers in the rubber industry.

Polymorphism of glutathione S-transferase P1 gene affects human vitamin C metabolism

There are large inter-individual differences in the metabolism of vitamin C (VC), which is composed of both ascorbic acid (AsA) and dehydroascorbic acid (DAsA). AsA is oxidized to DAsA in a series of xenobiotic reactions. Thus, the effects of polymorphism A313G (Ile105Val) in the gene for glutathione S-transferases P1 (GSTP1), one of the most active xenobiotic enzymes, on human VC metabolism were studied. The variant frequency of GSTP1 among the present subjects (n=210) was AA 71.0%; GA 27.0% and GG 1.9%. At 24 h after administration of 1 mmol of VC to young women (n=17; age, 21.0+/-1.1 y), total VC excretion (46.7+/-18.1mg) by AA homozygotes of GSTP1 was greater (p<0.0069) than that (28.2+/-14.0 mg) by GA heterozygotes. One hour after administration of VC, blood total VC levels were also significantly different (p<0.0036) between the homozygotes and heterozygotes. The effects of other polymorphisms in xenobiotic enzymes on VC metabolism were small.