Polymorphisms of glutathione S-transferase M1 and T1 modulate blood pressure of individuals chronically exposed to natural sour gas containing sulfur compounds

Expression Levels of Some Detoxification Genes in Liver and Testis of Rats Exposed to a Single Dose of Methyl-Tertiary Butyl Ether

AIM

Methyl-tertiary-butyl ether (MTBE), a well-known gasoline oxygenate compound, is still used in several countries. Several studies investigated the effects of MTBE on the activity of phase II metabolism enzymes. There is no published data on the effect(s) of short-term exposure to MTBE on mRNA levels of antioxidant genes. Therefore, the present study was carried out.

METHODS

A total of 15 adults male Wistar rats were randomly divided into five equal experimental groups. They received a single dose of 0, 400, 800 and 1600 mg/Kg MTBE in peanut oil by gavages. The final group received no MTBE and peanut oil. After 24 hr animals were slaughtered then livers and testis were removed to extract the total RNA. Real-time PCR was done to detect the gene expressions of glutathione S-transferase family (Gstt1, Gstm1, and Gstp1).

RESULTS

The mRNAs levels of the examined genes neither in liver nor in testis showed a significant difference between the exposed groups and control rats.

CONCLUSIONS

The present data revealed that exposure to a single dose of MTBE has no significant effect on the mRNA levels of the Gstt1, Gstm1, and Gstp1 genes.

The effect of glutathione S-transferase M1 and T1 polymorphisms on blood pressure, blood glucose, and lipid profiles following the supplementation of kale (Brassica oleracea acephala) juice in South Korean subclinical hypertensive patients

BACKGROUND/OBJECTIVES

Glutathione S-transferase (GST) forms a multigene family of phase II detoxification enzymes which are involved in the detoxification of reactive oxygen species. This study examines whether daily supplementation of kale juice can modulate blood pressure (BP), levels of lipid profiles, and blood glucose, and whether this modulation could be affected by the GSTM1 and GSTT1 polymorphisms.

SUBJECTS/METHODS

84 subclinical hypertensive patients showing systolic BP over 130 mmHg or diastolic BP over 85 mmHg received 300 ml/day of kale juice for 6 weeks, and blood samples were collected on 0-week and 6-week in order to evaluate plasma lipid profiles (total cholesterol, triglyceride, HDL-cholesterol, and LDL-cholesterol) and blood glucose.

RESULTS

Systolic and diastolic blood pressure was significantly decreased in all patients regardless of their GSTM1 or GSTT1 polymorphisms after kale juice supplementation. Blood glucose level was decreased only in the GSTM1-present genotype, and plasma lipid profiles showed no difference in both the GSTM1-null and GSTM1-present genotypes. In the case of GSTT1, on the other hand, plasma HDL-C was increased and LDL-C was decreased only in the GSTT1-present type, while blood glucose was decreased only in the GSTT1-null genotype.

CONCLUSIONS

These findings suggest that the supplementation of kale juice affected blood pressure, lipid profiles, and blood glucose in subclinical hypertensive patients depending on their GST genetic polymorphisms, and the improvement of lipid profiles was mainly greater in the GSTT1-present genotype and the decrease of blood glucose was greater in the GSTM1-present or GSTT1-null genotypes.

Alteration of serum sex hormonal profile in male gasoline filling station workers in respect to their polymorphism of glutathione S-transferase M1

Alterations in offspring sex ratio at birth and level of serum testosterone in filling-station workers have been reported. To determine the association of glutathione S-transferase M1 (GSTM1) polymorphism with serum levels of total testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) of male filling-station workers, the present study was carried out on 114 gasoline workers and 100 age- and sex-matched controls with no occupational exposure to gasoline. We have found no significant difference between the workers and controls for levels of sex hormones in the presence of active GSTM1 genotype. Among subjects with the GSTM1 null genotype, there was significant difference between exposed and unexposed subjects for the concentration of testosterone (t=4.37, df=97, P<0.001). To investigate whether one null genotype could be compensated by an active genotype for the other isoenzyme, the mean concentrations of sex hormones was compared between the exposed and control groups with respect to their combinations of the GSTM1 and GSTT1 genotypes. The exposed group having either "null GSTM1/positive GSTT1" (t=2.76, df=72, P=0.007) or "null GSTM1/null GSTT1" (t=4.91, df=23, P<0.001) combinations had a lower testosterone compared with the controls. It seems that GSTM1 polymorphism has more effect on serum testosterone compared to the GSTT1 polymorphism, in exposed workers.

Age-related macular degeneration and genetic polymorphisms of glutathione S-transferases M1 (GSTM1) and T1 (GSTT1)

The aim of this study is to understand the multifactorial causes of age-related macular degeneration (ARMD), and, therefore, it is reasonable to investigate whether genetic polymorphisms of antioxidant enzymes (GSTM1 and GSTT1) contribute to the development of ARMD. This study consisted of 112 subjects (44 females, 68 males) with exudative ARMD, who were recruited from Khalili Hospital ophthalmic clinic in Shiraz (southern Iran), referred by vitreoretinal surgeon. Also 112 sex-matched controls (44 females, 68 males) were randomly selected from unrelated volunteers in the same clinic. We excluded patients and controls with cataract or past history of cataract surgery, asthma, past history of malignancy, cardiovascular disease that on medication and known cases of glaucoma, because these traits were associated with GSTM1 and/or GSTT1 polymorphisms. There was no association between polymorphisms of neither GSTM1 nor GSTT1 and risk of ARMD. The combination genotypes of GSTM1 and GSTT1 were not associated with the risk of ARMD. We considered the time of deterioration of vision as the time of onset of exudative ARMD. The Kaplan-Meier analysis revealed that there was significant difference between genotypes of GSTM1 (log rank statistic = 7.03, df = 1, P = 0.008). The age at onset among GSTM1 null genotype was lower than the active genotype of GSTM1. Our results support the hypothesis that the protein encoded by the GSTM1 gene might have a protective function against oxidative stress in retina. Since the age at onset is influenced by the GSTM1 polymorphism, this implies that GSTM1 is a modifier gene.

The role of glutathione S- transferase M1 and T1 gene polymorphisms and oxidative stress-related parameters in Egyptian patients with essential hypertension

BACKGROUND

Essential hypertension is a complex, multifactorial, polygenic disease in which the underlying genetic components remain unknown. Glutathione S-transferase (GST) enzyme is involved in detoxification of reactive oxygen species. This study aimed to investigate GSTM1 and GSTT1 gene polymorphisms in Egyptian essential hypertensive patients and their relationship with oxidative stress-related parameters.

METHODS

The study included 40 newly-diagnosed, untreated, essential hypertensive patients and 40 normotensive subjects. Plasma levels of malondialdehyde (MDA), and nitrate/nitrite and erythrocyte reduced glutathione (GSH), activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and glutathione S-transferase (GST) were measured. Genotyping for GSTM1 and GSTT1 was performed.

RESULTS

The frequency of GSTM1+ve/GSTT1+ve in hypertensives (5%) was lower than in normotensives (37.5%).The frequency of GSTM1-ve/GSTT1-ve was elevated in hypertensives (35%) as compared to normotensives (7.5%). Plasma MDA was higher and nitrate/nitrite was lower in hypertensives than in normotensives. Erythrocyte GSH, activities of CAT, SOD, GSH-Px, and GST of hypertensives were lower than normotensives. Moreover, GST activity was lower in subjects with GSTM1-ve/GSTT1-ve than in those with GSTM1+ve/GSTT1+ve. In hypertensives, both systolic and diastolic blood pressures were negatively correlated with activities of CAT, GSH-Px, and GST.

CONCLUSIONS

GSTM1-ve/GSTT1-ve is a potential genetic factor to predict development of essential hypertension and permit early therapeutic intervention. The significant association between blood pressure and oxidative stress-related parameters indicates the pathogenic role of oxidative stress in hypertension. Antioxidants could be useful in the management of essential hypertension to prevent progressive deterioration and target organ damage however, further studies involving long-term clinical trials may help to assess the efficacy of these therapeutic agents.

Glutathione S-transferase genetic polymorphisms (GSTM1, GSTT1 and GSTO2) in three Iranian populations

Genetic polymorphisms in genes encoding glutathione S-transferases M1 (GSTM1; a member of class mu), T1 (GSTT1; a member of class theta) and O2 (GSTO2; a member of class omega) have been defined previously. Studies have revealed that there were significant differences between populations for allelic frequencies of GSTT1, GSTM1 and GSTO2 N412D polymorphisms. To get more insight into the genetic structure of Iranian populations the present study was done on Iranian Georgians living in Frydoonshahr (Isfahan province) and two Persian populations who living in Shiraz (Fars province) and Frydoonshahr. Study subjects consisted of 401 unrelated healthy individuals. From these 121 were Georgians. The remaining subjects were Persians from either Frydoonshahr (n = 34) or Shiraz (n = 246). The genetic polymorphism of GSTT1, GSTM1 and GSTO2 N412D was detected by PCR-based method. The frequency of GSTT1 null genotype in Georgian and Persians of Frydoonshahr and Shiraz was 15.7, 35.2 and 24.8%, respectively. There was significant difference between these populations for the distributions of the GSTT1 genotypes (chi(2) = 7.00, df = 2, P = 0.030). No significant difference was observed between these populations for polymorphisms of GSTM1 (chi(2) = 1.682, df = 2, P = 0.431) and GSTO N142D (chi(2) = 4.622, df = 4, P = 0.328). The prevalence of GSTT1 null genotype in Iranian Georgians showed significant difference with Persians and other Asian countries, but it seems to be similar with the frequency which was reported from European populations.

Association between genetic polymorphism of GSTT1 and depression score in individuals chronically exposed to natural sour gas

In order to investigate the association between effects of genetic polymorphisms of GSTT1 and GSTM1 and depression score of individuals chronically exposed to natural sour gas containing sulfur compounds, the present cross-sectional study was done. The study was performed on 124 healthy females living in the polluted area of Masjid-i-Sulaiman (MIS; Khozestan province, southwest of Iran). The GSTT1 and GSTM1 genotypes were determined using a polymerase chain reaction (PCR)-based method. Depression and hopelessness scores were determined by means of Beck's depression inventory (BDI) and Beck's hopelessness scale (BHS), respectively. The BHS score was positively correlated to the depression score (beta=0.687, t=10.474, p<0.001). The GSTT1 active genotype decreased the BDI score (beta=-0.161, t=-2.451, p=0.016). Polymorphism of GSTM1 may not be a good predictive factor for BDI (beta=-0.056, t=-0.857, p=0.393). There is no evidence for additive effect of GSTM1 and GSTT1 polymorphisms on BDI score. It is supposed that chronic exposure to natural sour gas may positively associated with DNA strand breaks and apoptosis in brain, especially in GSTT1 null genotype persons; finally living in the contaminated areas of MIS is associated with high BDI score.

Genetic polymorphisms of glutathione S-transferase T1 (GSTT1) and alterations of sex hormones in filling-station workers

OBJECTIVE

To determine the health effects of gasoline exposure as measured by levels of sex hormones (total testosterone, follicle-stimulating hormone [FSH], and luteinizing hormone [LH]) of male filling-station workers.

DESIGN

Case-control study.

SETTING

Filling stations in Shiraz (Fars province, Iran).

PATIENT(S)

One hundred fourteen male gasoline workers and 112 age-matched (+/-5 years) and sex-matched controls with no occupational exposure to gasoline.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Serum levels of testosterone, FSH, and LH, and expression of the GSTT1 genotype.

RESULT(S)

All hormone measurements were in the normal range although subclinical changes were detected in some indexes. Men exposed to petrochemicals had lower mean serum testosterone levels compared with unexposed men, regardless of the presence of the GSTT1 genotype. However, this decrease (expressed as mean +/- standard deviation) is most pronounced in the group possessing the GSTT1-null genotype (4.26 +/- 1.44 ng/mL vs. 5.48 +/- 0.98 ng/mL) compared with the group possessing the GSTT1 genotype (4.23 +/- 1.73 ng/mL vs. 4.67 +/- 1.21 ng/mL). The LH levels varied between the two groups; the mean serum LH was lower in the exposed versus unexposed men who possessed the GSTT1 genotype (2.82 +/- 1.32 IU/L vs. 3.20 +/- 1.17 IU/L) and higher in the exposed versus unexposed men who possessed the GSTT1-null genotype (3.52 +/- 1.37 IU/L vs. 2.76 +/- 1.07 IU/L).

CONCLUSION(S)

Testosterone levels were statistically significantly decreased in male gasoline workers compared with men who had had no occupational exposure to gasoline. The relevance of the GSTT1 genotype to these differences remains to be determined.

Genetic polymorphism of GSTT1 may be under natural selection in a population chronically exposed to natural sour gas

OBJECTIVE

In order to examine whether chronic exposure to natural sour gas containing sulfur compounds act as natural selection force on genetic polymorphisms of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1), the present study was done.

METHODS

The study was performed on two groups of healthy individuals of Masjid-i-Sulaiman (Khozestan province, southwest of Iran) citizens with the mean ages of 47.5 +/- 12.4 (36 male and 58 female) and 16.3 +/- 2.4 (47 male and 140 female) that were considered as first and second generation, respectively. The GSTT1 and GSTM1 genotypes were determined using a PCR-based method.

RESULTS

The genotypic frequencies of GSTM1 did not change significantly (chi(2) = 0.085, df = 1, P = 0.770). The frequency of the GSTT1 null genotype was 52.1% in the first generation and reached to 36.4% in the second generation. There was significant difference between two generations for the GSTT1 polymorphism (chi(2) = 6.397, df = 1, P = 0.011).

CONCLUSION

It was suggested that the GSTT1 polymorphism may be under natural selection because of probably favored ability of GSTT1-active genotype to survival and reproduction.

Alterations of liver function test indices of filling station workers with respect of genetic polymorphisms of GSTM1 and GSTT1

To determine the health effects of gasoline exposure on liver function test indices of filling station workers the present study was done. This case-control study was conducted in Shiraz on 56 male gasoline workers and 56 age- and sex-matched control subjects with no occupational exposure to gasoline. To elucidate the role of hepatic detoxifying enzymes, the genotypes of glutathione-S-transferases (GST) M1 and T1 were determined. Data analysis was done by multiple linear regression analysis and non-parametric Kruskal-Wallis test. The present study showed that all measurements were in normal range, although sub-clinical changes were detected in some indices. In liver function tests, exposure was associated with lower serum albumin (t=-3.88, P<0.001) and total proteins (t=-3.016, P=0.003) but higher alanine aminotransferase (t=2.856, P=0.005) and aspartate aminotransferase (t=2.11, P=0.038) levels in workers comparing to controls. Other investigators reported that GSTs involved in detoxification of several toxins including some of the compounds present in gasoline. Therefore, the possible influence of GSTT1 and GSTM1 genetic polymorphisms on alteration of liver function tests indices was investigated. The present findings showed that the genotype combinations of GSTM1 and GSTT1 did not alter the effects of exposure to gasoline in workers except for serum albumin. Serum albumin significantly decreased in workers with both active GST enzymes who had more than 5 years of employments (P=0.01). It is suggested that GSTM1 and GSTT1 are not involved in detoxification of toxicants present in gasoline which are hazardous to liver. Overall, due to detection of sub-clinical changes in hepatic test in gasoline station workers, exposure limitation and administrating safety device are recommended.

Influence of polymorphism of glutathione S-transferase M1 on systolic blood pressure of normotensive individuals

Studies have indicated that systolic (SBP) and diastolic (DBP) blood pressure are multi-factorial traits and significantly heritable. The aims of the present study are to assess whether the glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genotypes are associated with SBP and DBP of normotensive subjects and to ascertain whether the level of SBP and DBP given exposure to cigarette smoking is modified by the specific genetic polymorphisms of GSTM1 and GSTT1. This cross-sectional study was conducted on 140 subjects (49 females and 91 males) (mean age+/-SD: 38.7+/-14.7). The genotypes were determined using a polymerase chain reaction based method. Individuals were stratified according to the mean values of DBP and SBP, lower than or maximally same as the mean value defines as group I and higher than the mean value defines as group II. The logistic regression analyses were used. The best models fitted by logistic regression analysis for variables were associated with SBP and DBP. For analysis the combination of genotypes, sex, and smoking behavior was used as qualitative variables, and age, body mass index (BMI), and heart rate were used as covariates. Combination of "present-GSTT1, null-GSTM1" genotype (OR=0.001, 95% CI=0.00-0.439, P=0.025), heart rate (OR=1.065, 95% CI=1.018-1.114, P=0.006), and interaction between BMI and combination of "present-GSTT1, null-GSTM1" (OR=1.319, 95% CI=1.058-1.644, P=0.014) was associated with SBP. There was no association between either combination genotypes of GSTs or interaction of genotypes and smoking behavior on DBP. The present results suggest that the GSTM1 gene is one of the candidate genes that alter the baseline of SBP in normotensive individuals.

High incidence of suicide by burning in Masjid-i-Sulaiman (southwest of Iran), a polluted area with natural sour gas leakage

Masjid-i-Sulaiman (MIS) is located in the southwest of Iran. Unfortunately, some parts of MIS are contaminated by subsurface leakage of natural gas containing H(2)S. In order to investigate the possible effect(s) of chronic exposure to sulfur compounds on suicidal behavior, the present study was done. In the 2-year period, 561 individuals attempted suicide (260 men and 301 women). Completed suicide comprised of 19 men and 32 women. The rate per 100,000 person-years was 19.9 for men and 34.8 for women aged over 15 years. Forty-two (13 men and 29 women) of 561 patients were self-immolators by fire with a male:female ratio 0.45. This represents 22.4 burns per 100,000 person-years and is equivalent to 7.4% of all suicide attempts. Thirty-three of 42 patients died (78.6%) who were 9 men and 24 women with male:female ratio 0.37. There is statistically significant differences between sex groups (P((2)) = 0.0091). The self-inflicted burn was the most frequent method for lethal suicide. Winter was the most common season for self-burning followed by spring. Statistical analysis showed significant difference between seasons for self-inflicted burn (P((2)) = 0.00001). Analysis of correlation showed statistically positive correlation coefficient between mean values of all reactive sulfur compounds and seasonal frequency of suicide (r = 0.923, P((1)) = 0.038).

Genetic polymorphisms of glutathione S-transferases M1 and T1 modulate hematological changes of individuals chronically exposed to natural sour gas

In order to find the effect of genetic polymorphisms of glutathione S-transferase M1 (GSTM1) and GSTT1 on hematological changes of individuals chronically exposed to natural sour gas, the present study was done. Study subjects (59 males, 55 females) were residents of contaminated areas of Masjid-i-Sulaiman (southwest of Iran). The GSTM1 and GSTT1 genotypes were determined using a polymerase chain reaction-based method. The multiple linear regression method was applied. There is significant association between GSTs genotypes and either hemoglobin (t=2.185, P=0.031) or hematocrit (t=2.454, P=0.016). Also there is weak association between GSTs genotypes and WBC counts (t=1.802, P=0.074). The hemoglobin and hematocrit levels and WBC counts increased in individuals who had null genotypes of GSTM1 and GSTT1 compared to subjects with one or two active genes. Also the levels of hemoglobin and hematocrit and WBC counts increased in persons with one active genotype compared to subjects who had two active genes. There is no significant association between neither platelet nor WBC differential parameters and GSTs genotypes.

Null genotype of glutathione S-transferase M1 is associated with senile cataract susceptibility in non-smoker females

In the present study, we investigated whether the polymorphisms of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes are risk factors of cataract among Iranian population in a molecular epidemiological way. Blood samples from 150 subjects with cataract (72 male; 78 female) and 150 age- and sex-matched healthy persons were collected. Both patient and control groups were unrelated Iranian Muslims. Using PCR-based method, the genotypes were determined. The null GSTM1 genotype was associated with a 2.38-fold increase in the risk of developing cataract (OR=2.38; 95% CI=1.46-3.89; P = 0.0003). After stratification by sex of subjects, the association was apparent only among women (OR=3.20; 95% CI=1.58-6.52; P = 0.0007). The GSTT1 null genotype was associated with a 1.10-fold increased risk of developing cataract, but this association was not statistically significant. After stratification by sex of subjects, same results were obtained. Female patients with null genotype for GSTM1 and no history of smoking had a 3.45-fold increased cataract risk (P < 0.05), whereas females who were null for GSTM1 and having history of smoking were not at increased risk of cataract.