Risk of Atherosclerosis: Interaction of Smoking and Glutathione S-Transferase Genes:

Cross-Sectional Gene-Smoking Interaction Analysis in Relation to Subclinical Atherosclerosis-Results From the IMPROVE Study

BACKGROUND

Smoking is associated with carotid intima-media thickness (C-IMT). However, knowledge about how genetics may influence this association is limited. We aimed to perform nonhypothesis driven gene-smoking interaction analyses to identify potential genetic variants, among those included in immune and metabolic platforms, that may modify the effect of smoking on carotid intima-media thickness.

METHODS

We used baseline data from 1551 men and 1700 women, aged 55 to 79, included in a European multi-center study. Carotid intima-media thickness maximum, the maximum of values measured at different locations of the carotid tree, was dichotomized with cut point values ≥75, respectively. Genetic data were retrieved through use of the Illumina Cardio-Metabo- and Immuno- Chips. Gene-smoking interactions were evaluated through calculations of Synergy index (S). After adjustments for multiple testing, P values of <2.4×10-7 for S were considered significant. The models were adjusted for age, sex, education, physical activity, type of diet, and population stratification.

RESULTS

Our screening of 207 586 SNPs available for analysis, resulted in the identification of 47 significant gene-smoking synergistic interactions in relation to carotid intima-media thickness maximum. Among the significant SNPs, 28 were in protein coding genes, 2 in noncoding RNA and the remaining 17 in intergenic regions.

CONCLUSIONS

Through nonhypothesis-driven analyses of gene-smoking interactions, several significant results were observed. These may stimulate further research on the role of specific genes in the process that determines the effect of smoking habits on the development of carotid atherosclerosis.

Development of a polygenic risk score to improve detection of peripheral artery disease

INTRODUCTION

Peripheral artery disease (PAD) is a major cause of cardiovascular morbidity and mortality, yet timely diagnosis is elusive. Larger genome-wide association studies (GWAS) have now provided the ability to evaluate whether genetic data, in the form of genome-wide polygenic risk scores (PRS), can help improve our ability to identify patients at high risk of having PAD.

METHODS

Using summary statistic data from the largest PAD GWAS from the Million Veteran Program, we developed PRSs with genome data from UK Biobank. We then evaluated the clinical utility of adding the best-performing PRS to a PAD clinical risk score.

RESULTS

A total of 487,320 participants (5759 PAD cases) were included in our final genetic analysis. Compared to participants in the lowest 10% of PRS, those in the highest decile had 3.1 higher odds of having PAD (95% CI, 3.06-3.21). Additionally, a PAD PRS was associated with increased risk of having coronary artery disease, congestive heart failure, and cerebrovascular disease. The PRS significantly improved a clinical risk model (Net Reclassification Index = 0.07, p < 0.001), with most of the performance seen in downgrading risk of controls. Combining clinical and genetic data to detect risk of PAD resulted in a model with an area under the curve of 0.76 (95% CI, 0.75-0.77).

CONCLUSION

We demonstrate that a genome-wide PRS can discriminate risk of PAD and other cardiovascular diseases. Adding a PAD PRS to clinical risk models may help improve detection of prevalent, but undiagnosed disease.

Association of GSTM1 Deletion With Progression of CKD in Children: Findings From the Chronic Kidney Disease in Children (CKiD) Study

RATIONALE AND OBJECTIVE

Loss of function of the product of the GSTM1 gene has been implicated in rapid progression of adult CKD. Its role in pediatric CKD has not been previously described.

STUDY DESIGN

The study is a secondary analysis of a prospective observational cohort examining the association between deletions in GSTM1 and progression of CKD.

SETTING AND PARTICIPANTS

We used data and samples from the prospective Chronic Kidney Disease in Children (CKiD) cohort aged 1-16 years at enrollment with CKD.

EXPOSURE

We defined exposure fewer than two GSTM1 alleles on real-time polymerase chain reaction amplification.

OUTCOME

The primary outcome was a composite of 50% decrease in estimated glomerular filtration rate (eGFR) or start of kidney replacement therapy. Secondary outcomes included remission of proteinuria in children with glomerular disease and cardiovascular complications.

ANALYTIC APPROACH

The primary analysis was by Cox proportional hazards model. Analysis was adjusted for age, sex, race, ethnicity, BMI category, diagnosis category, and eGFR.

RESULTS

674 children were included in the analysis. Mean age at most recent visit was 11.9 years; 61% were male and 20% were Black. There were 241 occurrences of the primary outcome at the time of analysis. After adjustment for baseline characteristics, the risk of progression of CKD for exposed children was 1.94 (1.27, 2.97). The effect size was similar with either one or two deletions (autosomal dominant inheritance). The relationships between number of functional GSTM1 alleles and prespecified secondary outcomes were not statistically significant after adjustment.

LIMITATIONS

Missing data, especially for secondary outcomes, and relatively small sample size compared to genetic studies in adults.

CONCLUSIONS

GSTM1 deletion is associated with more rapid progression of pediatric CKD after adjustment in this large prospective cohort. No statistically significant associations were seen with secondary outcomes. If replicated, these findings may inform development of interventions for CKD in children.

An updated meta-analysis showed smoking modify the association of GSTM1 null genotype on the risk of coronary heart disease

Background Oxidative stress is considered to be involved in the pathogenesis of coronary heart disease (CHD). Glutathione-S-transferase (GST) enzymes play important roles in antioxidant defenses and may influence CHD risk. The present meta-analysis was performed to investigate the link between glutathione S-transferase M1 (GSTM1) null genotype and CHD and to get a precise evaluation of interaction between GSTM1 null genotype and smoking by the case-only design.

Methods PubMed and EMBASE databases were searched through 15 December 2020 to retrieve articles. Odds ratios (ORs) were pooled using either fixed-effects or random-effects models.

Results Thirty-seven studies showed that GSTM1 null genotype was associated with risk of CHD in total population, Caucasians and Asians (for total population, OR = 1.38, 95% confidence interval (CI): 1.15, 1.65; for Caucasians, OR = 1.34, 95% CI: 1.04, 1.72; for Asians, OR = 1.40, 95% CI: 1.11, 1.77). After adjustment for heterogeneity, these relationships were still significant. After adjustment for heterogeneity, case-only analysis of 11 studies showed a positive multiplicative interaction between GSTM1 null genotype and smoking (ever smoking vs. never smoking) (OR = 1.27, 95% CI: 1.08, 1.50; I² = 0%, P=0.553).

Conclusions The overall results indicated that GSTM1 null genotype was associated with a higher risk of CHD, and the association may be affected by smoking status. This is the first meta-analysis to prove a positive effect of the interaction between GSTM1 null genotype and smoking status on the risk of CHD. Well-designed studies are needed to investigate the possible gene–gene or gene–environment interactions.

Do GSTM1 and GSTT1 polymorphisms influence the risk of developing mitochondrial diseases in a Tunisian population?

Mitochondria play an essential role to supply the cell with metabolic energy in the form of adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS). As a consequence, they are also the primary source of cellular reactive oxygen species (ROS) which can cause oxidative damage of individual respiratory chain complexes. Indeed, affected OXPHOS subunits result in decreases in ATP production and increases in ROS formation which generate oxidative phosphorylation deficiency leading to mitochondrial dysfunctions. It has been suggested that ROS play a vital role in the pathogenesis of mitochondrial diseases. To the best of our knowledge, this is the first study which aimed to investigate the genetic variant effect of the antioxidant enzymes GSTM1 and GSTT1 on mitochondrial disease among a Tunisian population. In this report, 109 patients with mitochondrial disease and 154 healthy controls were genotyped by multiplex PCR amplification, and data were analyzed by SPSS v20 software. The results showed that GSTM1 null genotype was found to be associated with mitochondrial disease with a protective effect; however, no significant association of GSTT1 polymorphism with mitochondrial disease risk was revealed. But, interestingly, our findings highlight that GSTM1 active and GSTT1 null genotype combination increased by three fold the risk of developing mitochondrial disease with p _c  = 0.020, notably mitochondrial myopathy with p _c  = 0.046 and Leigh syndrome with p _c  = 0.042. In conclusion, this study suggests that GSTM1 active and GSTT1 null genotype combination might be a risk factor in developing mitochondrial disease.

Glutathione S-Transferase T1 (GSTT1) Null Polymorphism, Smoking, and Their Interaction in Coronary Heart Disease: A Comprehensive Meta-Analysis

BACKGROUND

The association between glutathione S-transferase T1 (GSTT1) null polymorphism and coronary heart disease (CHD) is inconsistent among studies, and data on the GSTT1 null genotype-smoking interplay in CHD is lacking. We conducted this meta-analysis to investigate the relationship between GSTT1 null polymorphism and CHD and to assess the potential interaction between GSTT1 null genotype and smoking.

METHODS

PubMed and EMBASE databases were searched up to 27 January 2016 using the appropriate terms. Odds ratios were pooled using either fixed-effects or random-effects models.

RESULTS

Twenty-nine articles including 31 studies with 15,004 cases and 35,597 controls were eligible. The random-effects model showed that the GSTT1 null genotype was associated with increased CHD risk (OR=1.213, 95%CI: 1.004-1.467; I²=90.4%). After excluding 10 studies detected by Galbraith plot, the fixed effects summary estimate also showed an increased risk of CHD (OR=1.14, 95% CI: 1.06-1.22; I²=27.7%). A case-only analysis including eight studies showed a statistically significant positive interaction between GSTT1 null polymorphism and smoking status on CHD (OR=1.34, 95% CI: 1.09-1.64; I²=0%). Sensitivity analyses further supported the associations. No publication bias was observed.

CONCLUSIONS

This meta-analysis suggests that GSTT1 null polymorphism is associated with the risk of CHD. To our knowledge, this is the first meta-analysis to prove a positive effect of the interaction between GSTT1 null genotype and smoking status on the risk of CHD. Future studies with detailed individual information are needed to confirm our findings.

Interaction between arsenic exposure from drinking water and genetic polymorphisms on cardiovascular disease in Bangladesh: a prospective case-cohort study

BACKGROUND

Epidemiologic data on genetic susceptibility to cardiovascular effects of arsenic exposure from drinking water are limited.

OBJECTIVE

We investigated whether the association between well-water arsenic and cardiovascular disease (CVD) differed by 170 single nucleotide polymorphisms (SNPs) in 17 genes related to arsenic metabolism, oxidative stress, inflammation, and endothelial dysfunction.

METHOD

We conducted a prospective case-cohort study nested in the Health Effects of Arsenic Longitudinal Study, with a random subcohort of 1,375 subjects and 447 incident fatal and nonfatal cases of CVD. Well-water arsenic was measured in 2000 at baseline. The CVD cases, 56 of which occurred in the subcohort, included 238 coronary heart disease cases, 165 stroke cases, and 44 deaths due to other CVD identified during follow-up from 2000 to 2012.

RESULTS

Of the 170 SNPs tested, multiplicative interactions between well-water arsenic and two SNPs, rs281432 in ICAM1 (padj = 0.0002) and rs3176867 in VCAM1 (padj = 0.035), were significant for CVD after adjustment for multiple testing. Compared with those with GC or CC genotype in rs281432 and lower well-water arsenic, the adjusted hazard ratio (aHR) for CVD was 1.82 (95% CI: 1.31, 2.54) for a 1-SD increase in well-water arsenic combined with the GG genotype, which was greater than expected given aHRs of 1.08 and 0.96 for separate effects of arsenic and the genotype alone, respectively. Similarly, the joint aHR for arsenic and the rs3176867 CC genotype was 1.34 (95% CI: 0.95, 1.87), greater than expected given aHRs for their separate effects of 1.02 and 0.84, respectively.

CONCLUSIONS

Associations between CVD and arsenic exposure may be modified by genetic variants related to endothelial dysfunction.

Pathophysiological Mechanisms of Tobacco-Related CVD

Cigarette smoking is a leading preventable risk factor for the development and progression of cardiovascular diseases (CVDs). Epidemiologic studies conclusively prove that both active smoking and secondhand smoke contribute significantly to morbidity and mortality related to CVD. Cigarette smoke is a mixture of several toxic chemicals, of which nicotine, carbon monoxide, and oxidant chemicals are most commonly implicated in the pathogenesis of cardiovascular disease. Tobacco causes endothelial dysfunction, inflammation, insulin resistance, alteration of lipid profile, hemodynamic alterations, and a hypercoagulable state. All of these act synergistically as pathobiologic mechanisms of atherothrombosis in tobacco users.

Interaction between arsenic exposure from drinking water and genetic susceptibility in carotid intima-media thickness in Bangladesh

Epidemiologic studies that evaluated genetic susceptibility for the effects of arsenic exposure from drinking water on subclinical atherosclerosis are limited. We conducted a cross-sectional study of 1078 participants randomly selected from the Health Effects of Arsenic Longitudinal Study in Bangladesh to evaluate whether the association between arsenic exposure and carotid artery intima-media thickness (cIMT) differs by 207 single-nucleotide polymorphisms (SNPs) in 18 genes related to arsenic metabolism, oxidative stress, inflammation, and endothelial dysfunction. Although not statistically significant after correcting for multiple testing, nine SNPs in APOE, AS3MT, PNP, and TNF genes had a nominally statistically significant interaction with well-water arsenic in cIMT. For instance, the joint presence of a higher level of well-water arsenic (≥ 40.4 μg/L) and the GG genotype of AS3MT rs3740392 was associated with a difference of 40.9 μm (95% CI = 14.4, 67.5) in cIMT, much greater than the difference of cIMT associated with the genotype alone (β = -5.1 μm, 95% CI = -31.6, 21.3) or arsenic exposure alone (β = 7.2 μm, 95% CI = -3.1, 17.5). The pattern and magnitude of the interactions were similar when urinary arsenic was used as the exposure variable. Additionally, the at-risk genotypes of the AS3MT SNPs were positively related to the proportion of monomethylarsonic acid (MMA) in urine, which is indicative of arsenic methylation capacity. The findings provide novel evidence that genetic variants related to arsenic metabolism may play an important role in arsenic-induced subclinical atherosclerosis. Future replication studies in diverse populations are needed to confirm the findings.

Glutathione S-transferase M1 polymorphism and coronary heart disease susceptibility: a meta-analysis involving 47,596 subjects

BACKGROUND

Many studies have investigated the association between glutathione S-transferase M1 (GSTM1) null genotype and the risk of coronary heart disease (CHD). However, the effect of the GSTM1 null genotype on CHD is still unclear because of apparent inconsistencies among those studies. A meta-analysis was performed to characterise the relationship more accurately.

METHODS

Pubmed, Embase, and Web of Science were searched. We estimated the summary odds ratio (OR) with a 95% confidence interval (95% CI) to assess the association.

RESULTS

Up to 26 case-control studies with 13,929 CHD cases and 33,667 control cases were included into this meta-analysis. Meta-analysis of the 26 studies showed that GSTM1 null genotype was associated with the risk of CHD (random effects OR=1.35, 95% CI 1.00 to 1.83). After adjustment for heterogeneity, meta-analysis showed that GSTM1 null genotype was not associated with increased risk of CHD in the total population (fixed effects OR=1.01, 95% CI 0.95 to 1.07). In the subgroup analysis by ethnicity, increased risks were not found for either Caucasians (OR=1.36, 95% CI=0.96-1.92) or Asians (OR=1.28, 95% CI=0.91-1.80). When stratified by smoking status, in the subgroup of smokers, GSTM1 null genotype was significantly associated with increased CHD risk (random effects OR=1.64, 95% CI 1.02 to 2.64). No evidence of publication bias was observed.

CONCLUSION

In conclusion, this meta-analysis suggested that there is overall lack of association between GSTM1 genotypes and CHD risk, however, GSTM1 null genotype when combining with smoking history may contribute to CHD susceptibility.

Copy Number Variation in Glutathione S-Transferases M1 and T1 and Ischemic Vascular Disease

Background—

Glutathione S-transferases (GSTs) M1 and T1 detoxify products of oxidative stress and may protect against atherosclerosis and ischemic vascular disease (IVD). We tested the hypothesis that copy number variation (CNV) in GSTM1 and GSTT1 genes, known to be associated with stepwise decreases in catalytic activity, predict risk of IVD.

Methods and Results—

We included 23 059 Danes from 2 general population studies and 2 case-control studies, of whom 4930 had ischemic heart disease (IHD) and 2086 had ischemic cerebrovascular disease. A real-time polymerase chain reaction method genotyped for the exact number of GSTM1 and GST T1 gene copies. We also performed meta-analyses, including our own and former studies, totaling 13 196 IHD cases and 33 228 controls. CNV in GSTM1 or GSTT1 or genotype combinations were not associated with an increased risk of IHD, myocardial infarction, ischemic cerebrovascular disease, ischemic stroke, or any ischemic vascular event in studies individually or combined or in the meta-analyses. Furthermore, genotypes did not interact with smoking on risk of disease end points. Finally, GST genotypes did not associate with markers of inflammation and oxidation or interact with smoking on markers of inflammation in the general population. In contrast, we observed the well-established association between CNV in GSTM1 and risk of bladder cancer.

Conclusions—

In studies including 6557 IVD cases and 16 502 controls and in meta-analyses of 13 196 cases and 33 228 controls, CNV in GSTM1 and GST T1 genes did not associate with risk of IVD or with markers of inflammation. These observations were independent of smoking exposure.

Functional polymorphisms of the GSTT-1 gene do not predict the severity of acute pancreatitis in the United States

BACKGROUND/AIM

Acute pancreatitis (AP) is an inflammatory response to pancreatic injury that is clinically classified as mild AP or severe AP, depending on specific criteria. Rahman and colleagues [Gastroenterology 2004;126:1312-1322] reported that genetic variation in the glutathione S-transferase theta-1 gene (GSTT-1) is associated with susceptibility and severity of AP in England. Our aim was to determine whether the same GSTT-1 polymorphism affects the severity of AP in a population from Pittsburgh, Pa., USA.

METHODS

Ninety-one consecutive patients with AP (19 severe) were prospectively evaluated. The GSTT-1 haplotypes were determined by PCR amplification in all patients and 268 controls. The resulting genotypes were classified as functional (GSTT-1*A/*A or *A/null) and nonfunctional (GSTT-1 null/null) phenotypes.

RESULTS

The relative frequencies of functional GSTT-1 phenotypes were similar in subjects with severe AP (15 of 19, 78.9%) and mild AP (61 of 72, 84.7%; p = 0.54) and in the controls (228 of 268, 85.1%; p = 0.66). Furthermore, the GSTT-1 functional and nonfunctional phenotypes were not associated with serum C-reactive protein levels (11.9 vs. 7.3 mg/dl; p = 0.19), interleukin-6 levels (74 vs. 60 pg/ml; p = 0.9), APACHE II scores (7 vs. 9; p = 0.26), or 48-hour Ranson scores (1 vs. 1; p = 0.63).

CONCLUSION

Functional GSTT-1 phenotypes do not correlate with susceptibility to AP or severity of AP in our patient population.

Micronuclei, genetic polymorphisms and cardiovascular disease mortality in a nested case-control study in Italy

AIM

To validate the predictive value of micronuclei (MN) in peripheral blood lymphocytes (PBL) and glutathione-S-transferases (GSTs) polymorphisms (GSTM1 and GSTT1) for mortality risk (MR) of cardiovascular diseases (CVD).

METHODS

Blood samples from 1650 healthy subjects selected from the general population were collected between June 1991 and November 1993, and slides were immediately prepared for MN assessment. The vital status, or the cause of death, was monitored for all subjects until January 2005. At the end of the follow-up, 111 deaths were recorded and 39 CVD cases were observed (age range=42-88 years). Two thousand binucleated (BN) cells/subject were scored for the MN assay and GSTs genotypes were assessed on the DNA extracted from the blood or serum samples.

RESULTS

A significantly higher MN frequency was recorded for the case group in comparison with the control group (n=67, Kruskall-Wallis test, p=0.006) and GSTT1 null genotype was significantly less frequent in CVD patients (chi(2)-test, p=0.036). The influence of other factors were evaluated using a unconditional logistic regression that confirmed a significant association of GSTT1 positive genotype with an increased OR for CVD (OR=6.29, 95% CI 1.32-29.95) beside a significant effect of age (OR=1.13, 95% CI 1.03-1.26 year(-1)). Finally, subjects with an higher MN frequency showed a higher MR for CVD (Log-rank test, p=0.001).

CONCLUSIONS

MN confirmed to be a suitable cytogenetic biomarker for early prediction of CVD death. The GSTT1 positive genotype is associated with an increased MR for CVD.

QTL-specific genotype-by-smoking interaction and burden of calcified coronary atherosclerosis: the NHLBI Family Heart Study

BACKGROUND

Calcified coronary plaque (CCP) is a complex trait influenced by both genes and environment, and plausibly an interaction between the two. Because the familial aggregation of CCP has been demonstrated and smoking is a significant, independent predictor of CCP, we assessed the evidence for genotype-by-smoking interaction and conducted linkage analysis of quantitative Agatston CCP scores in participants of the NHLBI Family Heart Study (FHS).

METHODS

During standardized clinical exams smoking habits were ascertained and CCP was quantified with cardiac computed tomography (CT). Among 4387 relationship pairs from 2128 Caucasian examinees variance component analysis was implemented in SOLAR to examine: (1) additive genotype-by-smoking status interaction using a variance component approach; (2) linkage analysis in the full sample and among smoking subsets defined by individual smoking exposure; (3) QTL-specific genotype-by-smoking interaction in the regions that appeared to differentiate between smoking strata.

RESULTS

The prevalence of CCP (and median Agatston score) was 75% (184.6) in men and 48% (51.0) in women. We detected four genome-wide significant logarithm of odds (LOD) scores in samples stratified by individual smoking exposure: chromosome 4 at 122cM (nearest marker D4S2297; robust adjusted LOD=3.1; q=0.053), chromosome 6 at 99cM (nearest marker D6S1056; robust adjusted LOD=3.3; q=0.053), chromosome 11 at 19cM (nearest marker D11S199; robust adjusted LOD=4.0; q=0.02) and chromosome 13 at 77cM (nearest marker D13S892; robust adjusted LOD=3.1; q=0.053). Additive and QTL-specific genotype-by-smoking interaction was detected on chromosomes 4, 6, 11 and 13; all P<0.05. Three of the four QTLs identified in this report have been previously linked to atherosclerosis and harbor interesting candidate genes.

CONCLUSIONS

These findings demonstrate the importance of considering complex interactions in the search for genes that influence the pathogenesis of CCP.

Genetic polymorphisms of glutathione S-transferases and the risk of adult brain tumors: a meta-analysis

BACKGROUND

Studies investigating the association between genetic polymorphisms of glutathione S-transferases (GST) and risk of adult brain tumors have reported conflicting results. The rationale of this meta-analysis was to determine whether GST variants increase the susceptibility of adult brain tumors by pooling data.

METHODS

Two investigators independently searched the HuGENet database, MEDLINE, EMBASE, conference articles, and manually reviewed bibliographies of retrieved articles. Papers were included if they were observational studies investigating the influence of GSTM1, GSTT1, GSTP1 I105V, or GSTP1 A114V on the development of adult brain cancers. Potential sources of heterogeneity between studies were explored in a meta-regression.

RESULTS

We identified eight eligible studies, which included 1,630 cases of glioma, 245 cases of meningioma, and 7,151 controls. Using the random effects model, there was no association between any of the GST variants and the risk of glioma [overall odds ratio (OR), 1.08; 95% confidence interval (95% CI), 0.95-1.22]. Subgroup analyses also showed no relationship between GST variants and histopathologic groups; the overall ORs were 1.13 (95% CI, 0.88-1.43) for high-grade glioma and 1.08 (95% CI, 0.76-1.55) for low-grade glioma. A random effects meta-regression suggested that the use of in-hospital controls produced larger effect estimates in glioma than the use of population controls (overall OR, 1.30; 95% CI, 1.03-1.65). The T1 null genotype was significantly associated with a risk of meningioma (OR, 1.95; 95% CI, 1.02-3.76), but the M1 variant was not.

CONCLUSION

This study did not suggest any relationship between GST variants and risks of glioma; the T1 null genotype may influence the susceptibility of meningioma, but larger studies are needed to substantiate this relationship.

A common variant in the glutathione S transferase gene is associated with elevated markers of inflammation and lipid peroxidation in subjects with diabetes mellitus

INTRODUCTION

Glutathione S transferases (GST) are enzymes responsible for the metabolism of numerous xenobiotics and play a major cellular antioxidant role. Our aim was firstly, to examine the association between the GST M1/GST mu-1 (GSTM1) and GST T1/GST theta-1 (GSTT1) gene variants with markers of oxidative stress and inflammation in diabetic patients, and secondly to examine the association and potential interaction between these variants and cigarette smoking.

METHODS

Seven hundred and seventy-three Caucasian subjects with diabetes and 2592 Caucasian non-diabetic subjects were successfully genotyped. Plasma total antioxidant status, C-reactive protein (CRP), oxidized-LDL (Ox-LDL) and LDL-mean/peak particle diameter were recorded in the diabetes sample.

RESULTS

No association was seen between genotype and cardiovascular disease (CVD) risk. In the diabetic subjects, GSTT1-1 compared to GSTT1-0 subjects had significantly higher CRP (p=0.001), Ox-LDL (p=0.004) and smaller LDL particles (p=0.01). In subjects without CVD, there was a significant interaction between the GSTT1-1 variant and smoking in determining Ox-LDL (p=0.04). Furthermore, CVD risk was higher in smokers compared to non-smokers with GSTT1-1. No significant associations were observed by GSTM1. Within the non-diabetic sample, no association was observed between genotype and prospective coronary heart disease (CHD) risk. Of note, the frequency of the GSTT1-1 variant was significantly lower in the diabetes subjects compared to the non-diabetic sample (p=0.01).

CONCLUSIONS

This study demonstrates an association between the GSTT1-1 variant and markers of inflammation and lipid peroxidation. Furthermore this variant interacts with smoking to increase lipid peroxidation.

Increased cardiovascular morbidity and mortality in type 2 diabetes is associated with the glutathione S transferase theta-null genotype: a Go-DARTS study

BACKGROUND

Glutathione S-transferases (GSTs) modulate oxidative stress, and variation in GST genes has been associated with cardiovascular disease risk. We prospectively determined smoking-related cardiovascular morbidity by GST genotype in a large cohort of individuals with type 2 diabetes using a population-based diabetes research database (DARTS).

METHODS AND RESULTS

We performed a cohort study of 2015 individuals with type 2 diabetes. Individuals were genotyped for the Ile105Val variant of GSTP1 and the deleted variants of GSTT1 and GSTM1. Clinical characteristics, smoking status, and incidence of subsequent cardiovascular events were obtained by examining the DARTS databases. Variation in the GSTP1 and GSTM1 genes was not associated with smoking-related risk of death or cardiovascular events. There was an increase in the rate of cardiovascular events in smokers lacking the GSTT1 gene compared with smokers with the GSTT1 gene intact (hazard ratio [HR], 1.96; P=0.001). This excess of cardiovascular events was due to both strokes (HR, 2.7; P=0.008) and myocardial infarctions (HR, 1.9; P=0.006). The rate of death as a result of a cardiovascular event was even more markedly increased in the GSTT1-null smokers (HR, 2.7; P=0.001), with a 2-fold increase in myocardial infarction fatality ratio. These effects translated into an increase in overall death and a decrease in age at death. We also found that the GSTT1- genotype was associated with progression of both diabetic retinopathy and nephropathy (P=0.005 and P=0.01, respectively), although we found little evidence for an interaction with smoking.

CONCLUSIONS

Genetic absence of the GSTT1 enzyme is an independent and powerful predictor of premature vascular morbidity and death in individuals with type 2 diabetes.

Glutathione S-transferase polymorphisms and survival from head and neck cancer

BACKGROUND

The purpose of this study was to evaluate the prognostic ability of polymorphisms of three genes involved in the metabolism of tobacco carcinogens (GSTT1, GSTM1, GSTP1) and one polymorphism of a DNA repair gene (XRCC1) for patients diagnosed with squamous cell carcinoma (SCC).

METHODS

Cox proportional hazard models were used to estimate risk of death for a prospective cohort of 190 patients.

RESULTS

Individuals with the GSTT1 functional genotype were twice as likely to die from any cause (hazard ratio [HR], 2.4; 95% confidence interval [CI], 1.13-4.97) and were three times as likely to die from SCC (HR, 3.4; 95% CI, 1.33-8.41) after adjustment for age, primary therapy, and stage of disease. The XRCC1 399 Gln genotype was predictive of disease recurrence.

CONCLUSIONS

Our findings, from one of the first studies to examine this research question, suggest that genomic markers of carcinogen metabolism and DNA repair capability may serve as prognostic indicators of disease recurrence and death.

Human Alpha Class Glutathione S‐Transferases: Genetic Polymorphism, Expression, and Susceptibility to Disease

The human alpha class glutathione S-transferases (GSTs) consist of 5 genes, hGSTA1-hGSTA5, and 7 pseudogenes on chromosome 6p12.1-6p12.2. hGSTA1-hGSTA4 have been well characterized as proteins, but hGSTA5 has not been detected as a gene product. hGSTA1-1 (and to a lesser extent hGSTA2-2) catalyzes the GSH-dependent detoxification of carcinogenic metabolites of environmental pollutants and tobacco smoke (e.g., polycyclic aromatic hydrocarbon diolepoxides) and several alkylating chemotherapeutic agents and has peroxidase activity toward fatty acid hydroperoxides (FA-OOH) and phosphatidyl FA-OOH. hGSTA3-3 has high activity for the GSH-dependent Delta(5)-Delta(4) isomerization of steroids, and hGSTA4-4 has high activity for the GSH conjugation of 4-hydroxynonenal. hGSTA4 is expressed in many tissues; hGSTA1-1 and hGSTA2-2 are expressed at high levels in liver, intestine, kidney, adrenal gland, and testis; and hGSTA3 is expressed in steroidogenic tissues. Functional, allelic, single nucleotide polymorphisms occur in an SP1-binding element of hGSTA1 and in the coding regions of hGSTA2 and hGSTA3. The main effects of these polymorphisms are the low hepatic expression of hGSTA1 in individuals homozygous for hGSTA1*B and the low specific activity of the hGSTA2E-2E variant toward FA-OOH. These properties suggest that alpha class GSTs will be involved in susceptibility to diseases with an environmental component (such as cancer, asthma, and cardiovascular disease) and in response to chemotherapy. Although hGSTM1, hGSTT1, and hGSTP1 have been associated with such diseases (on the basis of genetic polymorphisms as indicators of expression), alpha class GSTs have been little studied in this respect. Nevertheless, hGSTA1*B has been associated with increased susceptibility to colorectal cancer and with increased efficacy of chemotherapy for breast cancer. Methods for identification and quantitation of human alpha class GST protein, mRNA, and genotype are reviewed, and the potential for GST-alpha in plasma to be used as a marker for hepatic expression and induction is discussed.

Glutathione-S-transferase genotypes, smoking, and their association with markers of inflammation, hemostasis, and endothelial function: the atherosclerosis risk in communities (ARIC) study

Recent epidemiologic studies suggest that polymorphisms of glutathione-S-transferases M1 and T1 (GSTM1/GSTT1) modify the effects of cigarette smoking on risk of coronary heart disease (CHD). Since GSTs are able to detoxify numerous toxic compounds and products of oxidative stress, it is possible that GST genotypes may also modify the capacity of smoking to invoke a chronic inflammatory response. A cross-sectional analysis, using a subset of participants (n = 989) in a large (n = 15, 792) biracial cohort, was used to evaluate levels of nine markers of inflammation, hemostasis, and endothelial function by different combinations of GST genotypes and cigarette smoking status. Participants with the GSTM1 null (GSTM1-0) genotype and > or = 20 pack-years of smoking had the highest mean levels of CRP, fibrinogen, von Willebrand factor, ICAM-1, and VCAM-1 and lowest mean levels of albumin compared to other combinations of genotype and smoking. However, a formal test for interaction between GSTM1 genotype and smoking was statistically significant only for albumin. By contrast, participants who had the functional GSTT1 genotype (GSTT1-1) and smoked > or = 20 pack-years had the highest mean levels of only CRP and fibrinogen. The results of this study provide some limited evidence that GSTM1 and GSTT1 polymorphisms modify the effect of smoking on inflammation, hemostasis, and endothelial function.