Nullity of GSTT1/GSTM1 related to pesticides is associated with Parkinson's disease

Pesticide exposure and the development of Parkinson disease: a systematic review of Brazilian studies

Parkinson disease is the second most prevalent neurodegenerative disease globally. Parkinson disease etiology is not fully understood, it is believed to be a multifactorial disease. Pesticide exposure is highlighted among the factors. Thus, this study analyzed the relationship between pesticide exposure and the development of Parkinson disease in Brazil via a systematic review. The review was conducted following the PRISMA methodology and PICOS process, using the PubMed, Web of Science, and Virtual Health Library databases. Inclusion criteria were observational studies, conducted in humans, focusing on the Brazilian population, and investigating the relationship between pesticide exposure and Parkinson disease development. Studies quality was evaluated using the Hawker checklist. A total of 85 publications were identified for eligibility and 12 studies were included in the qualitative synthesis. Regarding study quality, two showed poor, nine moderate, and only one presented high quality. Moreover, 11 studies indicated an association between pesticide exposure and increased occurrence of Parkinson disease in Brazilian people. Additionally, such association was more prevalent in the presence of the following factors: (i) single-nucleotide polymorphism IVS1-7 A→G of PINK1; (ii) variations in the gene and protein expressions of the enzyme glutathione S-transferase; (iii) occupational exposure; (iv) living in a non-urban area; (v) low schooling level, and (iv) being male. This study is the first to infer, via the systematization of observational studies conducted with the Brazilian population, the association between pesticide exposure and the occurrence of Parkinson disease in the country, evidencing the necessity of efficient public policies.

Glutathione S-transferase: A keystone in Parkinson's disease pathogenesis and therapy

Parkinson's disease is a progressive neurodegenerative disorder that predominantly affects motor function due to the loss of dopaminergic neurons in the substantia nigra. It presents significant challenges, impacting millions worldwide with symptoms such as tremors, rigidity, bradykinesia, and postural instability, leading to decreased quality of life and increased morbidity. The pathogenesis of Parkinson's disease is multifaceted, involving complex interactions between genetic susceptibility, environmental factors, and aging, with oxidative stress playing a central role in neuronal degeneration. Glutathione S-Transferase enzymes are critical in the cellular defense mechanism against oxidative stress, catalysing the conjugation of the antioxidant glutathione to various toxic compounds, thereby facilitating their detoxification. Recent research underscores the importance of Glutathione S-Transferase in the pathophysiology of Parkinson's disease, revealing that genetic polymorphisms in Glutathione S-Transferase genes influence the risk and progression of the disease. These genetic variations can affect the enzymatic activity of Glutathione S-Transferase, thereby modulating an individual's capacity to detoxify reactive oxygen species and xenobiotics, which are implicated in Parkinson's disease neuropathological processes. Moreover, biochemical studies have elucidated the role of Glutathione S-Transferase in not only maintaining cellular redox balance but also in modulating various cellular signalling pathways, highlighting its neuroprotective potential. From a therapeutic perspective, targeting Glutathione S-Transferase pathways offers promising avenues for the development of novel treatments aimed at enhancing neuroprotection and mitigating disease progression. This review explores the evident and hypothesized roles of Glutathione S-Transferase in Parkinson's disease, providing a comprehensive overview of its importance and potential as a target for therapeutic intervention.

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

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

Case-Control Study of the Association between Single Nucleotide Polymorphisms of Genes Involved in Xenobiotic Detoxification and Antioxidant Protection with the Long-Term Influence of Organochlorine Pesticides on the Population of the Almaty Region

The association of genetic polymorphisms with the individual sensitivity of humans to the action of pesticide pollution is being actively studied in the world. The aim of this study was a molecular epidemiological analysis of candidate polymorphisms of genes involved in pesticide metabolism, detoxification, and antioxidant protection. Some of the selected polymorphisms also relate to susceptibility to cancer and cardiovascular, respiratory, and immune system diseases in individuals exposed to pesticides for a long time. For a case-control study of a unique cohort of people exposed to organochlorine pesticides for 10 years or more were chosen, a control cohort was selected that matched with the experimental group by the main population characteristics. PCR-PRLF and genome-wide microarray genotyping (GWAS) methods were used. We identified 17 polymorphisms of xenobiotic detoxification genes and 27 polymorphisms of antioxidant defense genes, which had a significantly high statistical association with the negative impact of chronic pesticide intoxication on human health. We also found 17 polymorphisms of xenobiotic detoxification genes and 12 polymorphisms of antioxidant defense genes that have a protective effect. Data obtained added to the list of potential polymorphisms that define a group at high risk or resistant to the negative effects of pesticides.

A Review of the GSTM1 Null Genotype Modifies the Association between Air Pollutant Exposure and Health Problems

Air pollution is one of the significant environmental risks known as the cause of premature deaths. It has deleterious effects on human health, including deteriorating respiratory, cardiovascular, nervous, and endocrine functions. Exposure to air pollution stimulates reactive oxygen species (ROS) production in the body, which can further cause oxidative stress. Antioxidant enzymes, such as glutathione S-transferase mu 1 (GSTM1), are essential to prevent oxidative stress development by neutralizing excess oxidants. When the antioxidant enzyme function is lacking, ROS can accumulate and, thus, cause oxidative stress. Genetic variation studies from different countries show that GSTM1 null genotype dominates the GSTM1 genotype in the population. However, the impact of the GSTM1 null genotype in modifying the association between air pollution and health problem is not yet clear. This study will elaborate on GSTM1's null genotype role in modifying the relationship between air pollution and health problems.

Genomic, transcriptomic, and metabolomic profiles of hiPSC-derived dopamine neurons from clinically discordant brothers with identical PRKN deletions

We previously reported on two brothers who carry identical compound heterozygous PRKN mutations yet present with significantly different Parkinson's Disease (PD) clinical phenotypes. Juvenile cases demonstrate that PD is not necessarily an aging-associated disease. Indeed, evidence for a developmental component to PD pathogenesis is accumulating. Thus, we hypothesized that the presence of additional genetic modifiers, including genetic loci relevant to mesencephalic dopamine neuron development, could potentially contribute to the different clinical manifestations of the two brothers. We differentiated human-induced pluripotent stem cells (hiPSCs) derived from the two brothers into mesencephalic neural precursor cells and early postmitotic dopaminergic neurons and performed wholeexome sequencing and transcriptomic and metabolomic analyses. No significant differences in the expression of canonical dopamine neuron differentiation markers were observed. Yet our transcriptomic analysis revealed a significant downregulation of the expression of three neurodevelopmentally relevant cell adhesion molecules, CNTN6, CNTN4 and CHL1, in the cultures of the more severely affected brother. In addition, several HLA genes, known to play a role in neurodevelopment, were differentially regulated. The expression of EN2, a transcription factor crucial for mesencephalic dopamine neuron development, was also differentially regulated. We further identified differences in cellular processes relevant to dopamine metabolism. Lastly, wholeexome sequencing, transcriptomics and metabolomics data all revealed differences in glutathione (GSH) homeostasis, the dysregulation of which has been previously associated with PD. In summary, we identified genetic differences which could potentially, at least partially, contribute to the discordant clinical PD presentation of the two brothers.

Effects of glutathione S-transferase M1 and T1 deletions on Parkinson's disease risk among a North African population

PURPOSE

In this study, the effects of glutathione S-transferase polymorphisms Mu1 (GSTM1) and glutathione S-transferase polymorphisms Theta1 (GSTT1) on Parkinson's disease (PD) risk factor were evaluated in a Tunisian population.

METHODS

These polymorphisms were analyzed in 229 healthy Tunisian subjects and 64 Tunisian patients with PD, using a polymerase chain reaction (PCR). Statistical analysis was performed using SPSS 18.0. The relative associations between the GST genotypes and PD were assessed by calculating the odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The study results demonstrated that the individuals with GSTM1 [OR=3.93, 95% CI: 1.98-7.92, P=10^-6] and GSTT1 [OR=5.45, 95% CI: 2.90-10.30, p=10^-6] were statistically associated with the risk of PD. A significant association was also found between the individuals with both GSTM1/T1 null genotypes and PD risk [OR=22.10, 95% CI: 6.99-73.75, P=10^-6].

CONCLUSION

These genotyping findings suggest that the absence of both GSTM1 and GSTT1 activity could be a contributory factor for the development of PD.

GC-MS Based Metabolic Profiling of Parkinson's Disease with Glutathione S-transferase M1 and T1 Polymorphism in Tunisian Patients

AIM AND OBJECTIVE

Parkinson's disease (PD) is the second most common neurodegenerative disease. It is a multifactorial disorder (caused by aging, environmental, and genetic factors). Metabolomics can help explore the biomarker profiles for aging. Recent studies showed an association between the glutathione S-transferases (GSTs) polymorphisms and PD risk. The purpose of this study was to evaluate the association of this genetic polymorphism and the metabolomic profile in PD Tunisian patients, in order to identify effective biomarkers in the genetic differentiation.

MATERIALS AND METHODS

In this study, the metabolomic profile changes related to GSTs polymorphism were searched in 54 Tunisian PD patients treated with L-dopa, using a gas chromatography-mass spectrometry (GC-MS) technique.

RESULTS

The study results showed that mannose, methyl stearate, and three other unknown metabolites, increased in patients with GSTM1 positive genotype, while glycolic acid, porphine, monomethyl phosphate, fumaric acid, and three other unknown metabolites decreased in patients with GSTM1 positive genotype. Subsequently, the levels of glycolic acid, erythronic acid, lactic acid, citric acid, fructose, stearic acid, 2-amino-2-methyl-1,3-propanediol and three other unknown metabolites increased in patients with GSTM1 positive genotype, while the levels of proline, valine and two unknown metabolites decreased with GSTT1 positive genotype.

CONCLUSION

All these altered metabolites are related to energy metabolism and it can be concluded that GSTs polymorphism based the shifting in energy metabolism and led to oxidative stress.

Association Between Parkinson's Disease and Melanoma: Putting the Pieces Together

Patients with Parkinson’s disease (PD) generally have reduced risk of developing many types of cancers, except melanoma—a malignant tumor of melanin-producing cells in the skin. For decades, a large number of epidemiological studies have reported that the occurrence of melanoma is higher than expected among subjects with PD, and the occurrence of PD is reciprocally higher than expected among patients with melanoma. More recent epidemiological studies further indicated a bidirectional association, not only in the patients themselves but also in their relatives. This association between PD and melanoma offers a unique opportunity to understand PD. Here, we summarize epidemiological, clinical, and biological evidence in regard to shared risk factors and possible underlying mechanisms for these two seemingly distinct conditions.

Gene-environment interactions between GSTs polymorphisms and targeted epigenetic alterations in hepatocellular carcinoma following organochlorine pesticides (OCPs) exposure

Exposure to environmental pollutant organochlorine pesticides (OCPs) and the role of tumour suppressor GSTs gene polymorphisms as well as epigenetic alterations have all been well reported in hepatocarcinogenesis. However, the interplay between environmental risk factors and polymorphic tumour suppressor genes or epigenetic factors in hepatocellular carcinoma (HCC) development remains ambiguous. Herein, we investigated the relationship of three GSTs polymorphisms (GSTT1 deletion, GSTM1 deletion, GSTP1 rs1695) as well as GSTP1 promoter region DNA methylation and HCC risk with a particular focus on the interaction with OCPs exposure among 90 HCC cases and 99 controls in a Chinese population. Serum samples were analysed for OCPs exposure employing gas chromatography coupled with mass selective detector (GC-MS). GSTs polymorphisms and epigenetic alterations were determined using high-resolution melting PCR (HRM PCR) and DNA sequencing. After adjusting for confounders (HBV infection, smoking, alcohol consumption, BMI, age, gender), OCPs exposure and GSTP1 methylation is significantly associated with elevated risk of HCC, while no significance is observed for GSTs polymorphisms. Moreover, the effects of OCPs exposure on HCC risk are more pronounced amongst GSTP1 (Ile/Val + Val/Val) and GSTP1 promoter methylation subjects than those who were GSTP1 (Ile/Ile) and unmethylated subjects. The interactions between OCPs exposure and GSTP1 genotype as well as GSTP1 epigenetic status are statistically significant. The current study demonstrates the importance of gene-environment interactions in the multifactorial development of HCC.

Genetic polymorphisms as determinants of pesticide toxicity: Recent advances

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Genetic polymorphisms may influence pesticides-induced oxidative damage.Pesticides modulate immune-system cells functionality, leading to the onset of a dangerous pro-inflammatory microenvironment.

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DNA repair genes, Cytochrome P450 s, PON and GST genes have a key role in the metabolism of xenobiotics.

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Many workers are professionally exposed to pesticides with potential health consequences.

Occupational and environmental exposure to pesticides may induce harmful effects on human health by promoting the development of a wide range of disorders. Some of the most recently hypothesized mechanisms are oxidative stress and epigenetic modifications, however biological effects seem to be modulated mainly by the occurrence of genetic polymorphisms. The susceptibility to exposure can be evaluated by studying the most common polymorphisms of genes involved in the metabolism of organophosphorus compounds (cytochrome P450, glutathione transferase, acetyltransferases or paraoxonase 1). The aim of this article is to review recent literature data concerning the influence of genetic polymorphisms on pesticides-induced oxidative damage.

Modulatory role of GSTT1 and GSTM1 in Punjabi agricultural workers exposed to pesticides

Glutathione S-transferases are important detoxification enzymes involved in the metabolism of endogenous as well as exogenous compounds. Individuals differ in metabolic capacity due to inherited genetic variations. Due to the polymorphism exhibited by GSTT1 and GSTM1 that results in the complete loss of function, the present study was aimed towards the determination of the frequency distribution of GSTT1 and GSTM1 in agricultural workers in Punjab, India. The study aimed to investigate their contribution in susceptibility to increased disease risk. A total of 513 subjects were included in this study, out of which 250 were agriculture workers and 263 were non-exposed occupationally. GSTT1 and GSTM1 null-genotype distribution was analyzed through multiplex-PCR method. Complete gene deletion in either of the genes was strongly associated with an increased risk (OR = 1.8; 95% CI = 1.3-2.6; p < 0.0008) of DNA/cytogenetic damage, cancer, infertility, and many other serious health effects. Therefore, homozygous deletion in GSTT1 or GSTM1 could play a modulatory role in health of workers with long-term exposure to pesticides.

Evidence-based update on rosacea comorbidities and their common physiologic pathways

Rosacea is a common chronic inflammatory disease affecting the facial skin whose etiology and pathophysiology are the subject of much investigation. Risk factors include genetic and environmental elements that may predispose individuals to localized inflammation and abnormal neurovascular responses to stimuli. Recent studies have introduced an array of systemic rosacea comorbidities, such as inflammatory bowel disease and neurologic conditions, that can be challenging to synthesize. We critically review the current data behind reported rosacea comorbidities and identify and highlight underrecognized physiologic mediators shared among rosacea and associated comorbidities. This information may be helpful in addressing patient questions about potential systemic implications of rosacea and can serve as a candidate platform for future research to understand rosacea and improve treatments.

Effects of Glutathione S-Transferase Gene Polymorphisms and Antioxidant Capacity per Unit Albumin on the Pathogenesis of Chronic Obstructive Pulmonary Disease

OBJECTIVES

To study the effects of GSTM1, GSTT1 gene polymorphisms, and organism antioxidant capacity and related indicators such as antioxidant capacity per unit of albumin (AC/ALB) on chronic obstructive pulmonary disease (COPD).

METHODS

Using polymerase chain reaction technology, GSTM1 and GSTT1 gene polymorphisms were detected in 33 COPD patients and 33 healthy people. The total antioxidant capacity (TAC) found in serum was determined using the I₂/KI potentiometric, KMnO₄ microtitration, and H₂O₂ potentiometric methods. The AC/ALB was defined as the TAC divided by the serum albumin concentration. Logistic regression analysis was carried out with biochemical screening indices, which was found to be closely related with the incidence of COPD.

RESULTS

The GSTM1 and GSTT1 gene deletion rate in the COPD group was significantly higher than that in the control group (P < 0.05). The differences in serum TAC between the COPD and control groups, GSTM1 (+) and GSTM1 (-) groups, and GSTT1 (+) and GSTT1 (-) groups were statistically significant (P < 0.001). In addition, there was a significant difference in the AC/ALB between the COPD and control groups (P < 0.05). Logistic regression analysis showed that the incidence of COPD was closely related to the AC/ALB (P < 0.05).

CONCLUSIONS

GSTM1 and GSTT1 gene polymorphisms are closely correlated with the pathogenesis of COPD, while the AC/ALB plays a decisive role in the occurrence and development of COPD.

A meta-analysis of association between glutathione S-transferase M1 gene polymorphism and Parkinson's disease susceptibility

The aim of this meta-analysis was to evaluate whether there was an association between glutathione S-transferase M1(GSTM1)gene polymorphism and Parkinson’s disease (PD) susceptibility by pooling published data.

We performed comprehensive electronic database search for articles published between February12,2015 and April30 2016. The published case-control or cohort studies related to GSTM1 gene polymorphism and Parkinson’s disease susceptibility were screened, reviewed, and included in this meta-analysis. The correlation between GSTM1 gene polymorphism and PD susceptibility was expressed by odds ratio (OR) and its corresponding 95% confidence interval (95%CI). Publication bias was evaluated by Begg’s funnel plot and Egger’s line regression test. All analysis was done by stata11.0 software.

After searching the PubMed, EMBASE, and CNKI databases, seventeen case-control studies with 3,538 PD and 5,180 controls were included in the final meta-analysis. The data was pooled by a fixed-effect model for lack of statistical heterogeneity across the studies; the results showed GSTM1 null expression can significant increase the susceptibility of PD (OR=1.11, 95% CI:1.01-1.21, P<0.05). Subgroup analysis indicated GSTM1 gene polymorphism was associated with PD susceptibility in the Caucasian ethnic group (OR=1.15, 95% CI:1.05-1.27, P<0.05) but not in the Asian ethnic group (OR=0.89, 95% CI:0.70-1.12, P>0.05). Begg’s funnel plot and Egger’s line regression test showed no significant publication bias.

Based on the present evidence, GSTM1 null expression can significant increase the susceptibility of PD in persons of Caucasian ethnicity.

Alpha-synuclein A53T mutation is not frequent on a sample of Brazilian Parkinson's disease patients

INTRODUCTION

The pathogenesis of Parkinson's disease (PD) involves both genetic susceptibility and environmental factors, with focus on the mutation in the alpha-synuclein gene (SNCA).Objective To analyse the polymorphism SNCA-A53T in patients with familial PD (FPD) and sporadic PD (SPD).

METHOD

A total of 294 individuals were studied, regardless of sex and with mixed ethnicity. The study group with 154 patients with PD, and the control group included 140 individuals without PD. The genotyping of SNCA-A53T was performed by PCR/RFLP. Significance level was p < 0.05.

RESULTS

Among all patients, 37 (24%) had FPD and 117 (75.9%) had SPD. The absence of SNCA-A53T mutation was observed in all individuals.

CONCLUSION

SPD is notably observed in patients. However, the SNCA-A53T mutation was absent in all individuals, which does not differ controls from patients. This fact should be confirmed in a Brazilian study case with a more numerous and older population.

The Genetic Architecture of Murine Glutathione Transferases

Glutathione S-transferase (GST) genes play a protective role against oxidative stress and may influence disease risk and drug pharmacokinetics. In this study, massive multiscalar trait profiling across a large population of mice derived from a cross between C57BL/6J (B6) and DBA2/J (D2)—the BXD family—was combined with linkage and bioinformatic analyses to characterize mechanisms controlling GST expression and to identify downstream consequences of this variation. Similar to humans, mice show a wide range in expression of GST family members. Variation in the expression of Gsta4, Gstt2, Gstz1, Gsto1, and Mgst3 is modulated by local expression QTLs (eQTLs) in several tissues. Higher expression of Gsto1 in brain and liver of BXD strains is strongly associated (P < 0.01) with inheritance of the B6 parental allele whereas higher expression of Gsta4 and Mgst3 in brain and liver, and Gstt2 and Gstz1 in brain is strongly associated with inheritance of the D2 parental allele. Allele-specific assays confirmed that expression of Gsto1, Gsta4, and Mgst3 are modulated by sequence variants within or near each gene locus. We exploited this endogenous variation to identify coexpression networks and downstream targets in mouse and human. Through a combined systems genetics approach, we provide new insight into the biological role of naturally occurring variants in GST genes.

A randomized, double-blind phase I/IIa study of intranasal glutathione in Parkinson's disease

BACKGROUND

Depletion of reduced glutathione is associated with PD and glutathione augmentation has been proposed as a disease-modifying strategy. The aim of this study was to determine the safety and tolerability of intranasal reduced glutathione in individuals with PD.

METHODS

Thirty individuals with PD were randomized to either placebo (saline), 300 mg/day, or 600 mg/day of intranasal glutathione in three divided daily doses. Follow-up visits included side effect screening of PD symptoms and cognition, blood chemistry, sinus irritation, and hyposmia. Tolerability was measured by frequency and severity of reported adverse events, compliance, and withdrawals from the study.

RESULTS

After 3 months, there were no substantial differences between groups in the number of adverse events reported or observed among all safety measures assessed. All groups met tolerability criteria.

CONCLUSIONS

These data support the safety and tolerability of intranasal glutathione in this population. Pharmacokinetic and dose-finding studies are warranted.

Glutathione transferases and neurodegenerative diseases

There is substantial agreement that the unbalance between oxidant and antioxidant species may affect the onset and/or the course of a number of common diseases including Parkinson's and Alzheimer's diseases. Many studies suggest a crucial role for oxidative stress in the first phase of aging, or in the pathogenesis of various diseases including neurological ones. Particularly, the role exerted by glutathione and glutathione-related enzymes (Glutathione Transferases) in the nervous system appears more relevant, this latter tissue being much more vulnerable to toxins and oxidative stress than other tissues such as liver, kidney or muscle. The present review addresses the question by focusing on the results obtained by specimens from patients or by in vitro studies using cells or animal models related to Parkinson's and Alzheimer's diseases. In general, there is an association between glutathione depletion and Parkinson's or Alzheimer's disease. In addition, a significant decrease of glutathione transferase activity in selected areas of brain and in ventricular cerebrospinal fluid was found. For some glutathione transferase genes there is also a correlation between polymorphisms and onset/outcome of neurodegenerative diseases. Thus, there is a general agreement about the protective effect exerted by glutathione and glutathione transferases but no clear answer about the mechanisms underlying this crucial role in the insurgence of neurodegenerative diseases.

Glutathione-Dependent Detoxification Processes in Astrocytes

Astrocytes have a pivotal role in brain as partners of neurons in homeostatic and metabolic processes. Astrocytes also protect other types of brain cells against the toxicity of reactive oxygen species and are considered as first line of defence against the toxic potential of xenobiotics. A key component in many of the astrocytic detoxification processes is the tripeptide glutathione (GSH) which serves as electron donor in the GSH peroxidase-catalyzed reduction of peroxides. In addition, GSH is substrate in the detoxification of xenobiotics and endogenous compounds by GSH-S-transferases which generate GSH conjugates that are efficiently exported from the cells by multidrug resistance proteins. Moreover, GSH reacts with the reactive endogenous carbonyls methylglyoxal and formaldehyde to intermediates which are substrates of detoxifying enzymes. In this article we will review the current knowledge on the GSH metabolism of astrocytes with a special emphasis on GSH-dependent detoxification processes.

Null genotype of GSTT1 contributes to increased Parkinson's disease risk in Caucasians: evidence from a meta-analysis

Conflicting results in previous case-control studies on the association between Glutathione S-transferase T1 (GSTT1) gene polymorphism and Parkinson's disease (PD) risk have been reported, so we conducted this meta-analysis. We searched and extracted data from 3 Chinese and 3 English web-based electronic databases to evaluate the associations by odds ratio (OR) and its 95% confidence interval (CI) under the recessive genetic comparison model (null genotype vs. present genotype). We also conducted subgroup analyses by ethnicity and adjusted status of OR, respectively. Meta-analyses and subgroup analyses of larger studies (sample size ≥300) were also reanalyzed. When 18 eligible studies (3,963 PD cases and 5,472 controls) were pooled to analyze the association, we found no statistically significant result (OR 1.24, 95% CI 0.96-1.60). In the subgroup analyses by ethnicity, there was statistically significant association between the null genotype of GSTT1 and PD risk among Caucasians, while the associations were not found among Asians and Latinos. In the subgroup analyses by adjusted status of OR, there were no significant associations both in studies with crude OR and adjusted OR. Meta-analyses and subgroup analyses of larger studies (sample size ≥300) were also confirmed the associations mentioned above. Power analysis indicated only meta-analysis of Caucasians had enough evidence to claim the association. In conclusion, the meta-analysis suggests that the null genotype of GSTT1 contributes to PD risk in Caucasians, and no association in Asians is needed more studies to confirm.