Relevance of the deletion polymorphisms of the glutathione S-transferases GSTT1 and GSTM1 in pharmacology and toxicology

Effects of Glutathione S-Transferases (GSTM1, GSTT1 and GSTP1) gene variants in combination with smoking or drinking on cancers: A meta-analysis

BACKGROUND

This meta-analysis aimed to systematically summarize the association between cancer risks and glutathione s-transferases (GSTs) among smokers and drinkers.

METHODS

Literature was searched through PubMed, Web of Science, CNKI, and WANFANG published from 2001 to 2022. Stata was used with fixed-effect model or random-effect model to calculate pooled odds ratios (ORs) and the 95% confidence interval (95% CI). Sensitivity and heterogeneity calculations were performed, and publication bias was analyzed by Begg and Egger's test. Regression analysis was performed on the correlated variables about heterogeneity, and the false-positive report probabilities (FPRP) and the Bayesian False Discovery Probability (BFDP) were calculated to assess the confidence of a statistically significant association.

RESULTS

A total of 85 studies were eligible for GSTs and cancer with smoking status (19,604 cases and 23,710 controls), including 14 articles referring to drinking status (4409 cases and 5645 controls). GSTM1-null had significant associations with cancer risks (for smokers: OR = 1.347, 95% CI: 1.196-1.516, P < .001; for nonsmokers: OR = 1.423, 95% CI: 1.270-1.594, P < .001; for drinkers: OR = 1.748, 95% CI: 1.093-2.797, P = .02). GSTT1-null had significant associations with cancer risks (for smokers: OR = 1.356, 95% CI: 1.114-1.651, P = .002; for nonsmokers: OR = 1.103, 95% CI: 1.011-1.204, P = .028; for drinkers: OR = 1.423, 95% CI: 1.042-1.942, P = .026; for nondrinkers: OR = 1.458, 95% CI: 1.014-2.098, P = .042). Negative associations were found between GSTP1rs1695(AG + GG/AA) and cancer risks among nondrinkers (OR = 0.840, 95% CI: 0.711-0.985, P = .032).

CONCLUSIONS

GSTM1-null and GSTT1-null might be related cancers in combination with smoking or drinking, and GSTP1rs1695 might be associated with cancers among drinkers.

Disorders of Endogenous and Exogenous Antioxidants in Neurological Diseases

In diseases of the central nervous system, such as Alzheimer's disease (AD), Parkinson's disease (PD), stroke, amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and even epilepsy and migraine, oxidative stress load commonly surpasses endogenous antioxidative capacity. While oxidative processes have been robustly implicated in the pathogenesis of these diseases, the significance of particular antioxidants, both endogenous and especially exogenous, in maintaining redox homeostasis requires further research. Among endogenous antioxidants, enzymes such as catalase, superoxide dismutase, and glutathione peroxidase are central to disabling free radicals, thereby preventing oxidative damage to cellular lipids, proteins, and nucleic acids. Whether supplementation with endogenously occurring antioxidant compounds such as melatonin and glutathione carries any benefit, however, remains equivocal. Similarly, while the health benefits of certain exogenous antioxidants, including ascorbic acid (vitamin C), carotenoids, polyphenols, sulforaphanes, and anthocyanins are commonly touted, their clinical efficacy and effectiveness in particular neurological disease contexts need to be more robustly defined. Here, we review the current literature on the cellular mechanisms mitigating oxidative stress and comment on the possible benefit of the most common exogenous antioxidants in diseases such as AD, PD, ALS, HD, stroke, epilepsy, and migraine. We selected common neurological diseases of a basically neurodegenerative nature.

Evaluation of Systemic Genotoxic/Oxidative and Proinflammatory Effects in Workers of a Titanium Dioxide Production Plant

This study is aimed at evaluating whether the occupational exposure to TiO₂ during the industrial production process is able to induce genotoxic, oxidative, and inflammatory effects on blood, biomonitoring the same workers that showed micronucleus induction in the exfoliated buccal cells, as previous published. The final aim was to find sensitive and suitable biomarkers to evaluate potential early toxicity of occupational exposure to TiO₂. On the same 40 workers involved in the manufacture of TiO₂ pigment, 5 office workers, and 18 controls previously studied, we used formamidopyrimidine glycosylase- (Fpg-) comet assay on lymphocytes to evaluate genotoxic/oxidative effects and detected cytokine (IL-6, IL-8, and TNFα) release by ELISA to evaluate proinflammation. Moreover, we studied the possible influence of single nucleotide polymorphisms of XRCC1 and hOGG1 DNA repair genes and of GST metabolism-related genes (GSTT1 and GSTM1) on the evaluated effects. We did not find statistically significant differences in the mean values of the analysed Fpg-comet assay parameters; only the percentage of DNA damaged cells appearing in the test as comets (% comets) resulted higher in the exposed workers compared to controls. Also, the data analysed taking into account the specific task (bagging, industrial cleaning, mobile operations, maintaining, and production) showed differences only for % comets which resulted higher in industrial cleaners compared to controls. We found variations of IL-6 and IL-8 levels in the exposed workers with concentrations that were lower for IL-6 and higher for IL-8 compared to the control group. XRCC1, hOGG1, and GSTT1 polymorphisms did not influence neither comet parameters nor cytokine release. These findings demonstrate that TiO₂ production process is able to induce slight proinflammatory effects in terms of IL-8 increased release but not significant genotoxic/oxidative effects on lymphocytes, which do not seem to be a target of TiO₂, prevalently inhalable particles, generated in the studied production site.

Spotlight on contributory role of host immunogenetic profiling in SARS-CoV-2 infection: Susceptibility, severity, mortality, and vaccine effectiveness

BACKGROUND

The SARS-CoV-2 virus has spread continuously worldwide, characterized by various clinical symptoms. The immune system responds to SARS-CoV-2 infection by producing Abs and secreting cytokines. Recently, numerous studies have highlighted that immunogenetic factors perform a putative role in COVID-19 pathogenesis and implicate vaccination effectiveness.

AIM

This review summarizes the relevant articles and evaluates the significance of mutation and polymorphism in immune-related genes regarding susceptibility, severity, mortality, and vaccination effectiveness of COVID-19. Furthermore, the correlation between host immunogenetic and SARS-CoV-2 reinfection is discussed.

METHOD

A comprehensive search was conducted to identify relevant articles using five databases until January 2023, which resulted in 105 total articles.

KEY FINDINGS

Taken to gather this review summarized that: (a) there is a plausible correlation between immune-related genes and COVID-19 outcomes, (b) the HLAs, cytokines, chemokines, and other immune-related genes expression profiles can be a prognostic factor in COVID-19-infected patients, and (c) polymorphisms in immune-related genes have been associated with the effectiveness of vaccination.

SIGNIFICANCE

Regarding the importance of mutation and polymorphisms in immune-related genes in COVID-19 outcomes, modulating candidate genes is expected to help clinical decisions, patient outcomes management, and innovative therapeutic approach development. In addition, the manipulation of host immunogenetics is hypothesized to induce more robust cellular and humoral immune responses, effectively increase the efficacy of vaccines, and subsequently reduce the incidence rates of reinfection-associated COVID-19.

Absence of GSTT1 and polymorphisms in GSTP1 and TP53 are associated with the incidence of acne vulgaris

BACKGROUNDS

Acne vulgaris is a chronic inflammatory skin disease of the pilosebaceous unit affecting most teenagers and numerous adults throughout the world. The present study was designed to assess the association of the presence or absence of GSTM1, GSTT1, and single nucleotide polymorphisms rs1695 in GSTP1 and rs1042522 in TP53 gene with acne vulgaris.

METHODS

The cross-sectional case-control study was conducted at the Institute of Zoology from May 2020 to March 2021 and included acne vulgaris patients (N = 100) and controls (N = 100) enrolled in Dera Ghazi Khan district, Pakistan. Multiplex and tetra-primer amplification refractory mutation system-polymerase chain reactions were applied to investigate the genotype in analyzed genes. The association of rs1695 and rs1042522 with acne vulgaris was studied either individually or in various combinations with GATM1 and T1.

RESULTS

A significant association of absence of GSTT1 and mutant genotype at rs1695 (GG) and at rs1042522 (CC) in GSTP1 and TP53, respectively, was found to be associated with acne vulgaris in enrolled subjects. Subjects aged 10-25 years and smokers were more susceptible to acne vulgaris.

CONCLUSION

Our results suggest that genotypes of glutathione S-transferases (GSTs) and TP53 are involved in protection against oxidative stress and may influence disease progression in acne vulgaris.

Polymorphisms in drug metabolism genes as a risk factor for first-line anti-tuberculosis drug-induced liver injury

BACKGROUND

Anti-tuberculosis drug-induced liver injury (AT-DILI) is one of the most common side effects in TB patients during treatment. The prime cause of liver injury during TB treatment is reported to be isoniazid and its metabolites. Different factors influenced the development of AT-DILI, and genetic factors are one of the major factors.

METHODS AND RESULTS

Polymorphisms in drug metabolism genes like NAT2, CYP2E1, PXR, and GST have been reported to be associated with AT-DILI, and they are one of the major areas of focus at present. Attempts are met in this review to analyse the different markers in these drug metabolism genes for their association with AT-DILI.

CONCLUSION

A better understanding of the polymorphisms in these genes and their functional effects will give better insights into the development of AT-DILI, and it could facilitate in designing and developing more effective personalized treatment for TB.

Auto repair workers exposed to PM2.5 particulate matter in Barranquilla, Colombia: telomere length and hematological parameters

Exposure to 2.5 µm particulate matter (PM_2.5) in automotive repair shops is associated with risks to health. We evaluated the effects of occupational exposure to PM_2.5 among auto repair-shop workers. Blood and urine samples were collected from 110 volunteers from Barranquilla, Colombia: 55 active workers and 55 controls. PM_2.5 concentrations were assessed at each of the sampling sites and chemical content was analyzed by SEM-EDS electron microscopy. The biological samples obtained were peripheral blood (hematological profiling, DNA extraction) and urine (malondialdehyde concentration). Telomere length was assessed by qPCR and polymorphisms in the glutathione transferase genes GSTT1 and GSTM1 by PCR-RFLP, with confirmation by allelic exclusion. White blood cell (WBC), lymphocyte (LYM%) and platelet (PLT) counts and the malondialdehyde concentration were higher (4.10 ± 0.93) in the exposed group compared to the control group (1.56 ± 0.96). TL was shorter (5071 ± 891) in the exposed individuals compared to the control group (6271 ± 805). White blood cell (WBC) and platelet counts were positively associated with exposure. Age and TBARS were correlated with TL in exposed individuals. The GSTT1 gene alleles were not in Hardy-Weinberg (H-W) equilibrium. The GSTM1 gene alleles were in H-W equilibrium and allelic exclusion analysis confirmed the presence of heterozygous GSTM1 genotypes. SEM-EDS analysis showed the presence of potentially toxic elements, including Mg, Al, Fe, Mn, Rh, Zn, and Cu. Auto repair shop workers showed effects that may be associated with exposure to mixtures of pollutants present in PM_2.5. The GSTM1 and GSTT1 genes had independent modulatory effects.

Phase I Metabolism of Pterostilbene, a Dietary Resveratrol Derivative: Metabolite Identification, Species Differences, Isozyme Contribution, and Further Bioactivation

Pterostilbene (PTE), a dietary derivative of resveratrol, displayed pleiotropic health-promoting activities. This study aimed to explore the metabolic profiles and species differences of the phase I metabolism of PTE and to investigate subsequent detoxification after PTE bioactivation. PTE was found to be biotransformed to two pharmacologically active metabolites, pinostilbene and 3'-hydroxypterostilbene, in vivo and in vitro with substantial species differences. Human CYP1A2 was proved to be mainly responsible for the demethylation and 3'-hydroxylation of PTE, with its contribution to a demethylation of 94.5% and to a 3'-hydroxylation of 97.9%. An in vitro glutathione trapping experiment revealed the presence of an ortho-quinone intermediate formed by further oxidation of 3'-hydroxypterostilbene. Human glutathione S-transferase isoforms A2, T1, and A1 inactivated the ortho-quinone intermediate by catalyzing glutathione conjugation, implicating a potential protective pathway against PTE bioactivation-derived toxicity. Overall, this study provided a comprehensive view of PTE phase I metabolism and facilitated its further development as a promising nutraceutical.

Evaluation of genetic instability, oxidative stress, and metabolism-related gene polymorphisms in workers exposed to waste anesthetic gases

Professionals who work in operating rooms (ORs) may be exposed daily to waste anesthetic gases (WAGs) due to the use of inhalational anesthetics. Considering the controversial findings related to genetic damage and redox status in addition to a lack of knowledge about the effect of polymorphisms in genes related to phase I and II detoxification upon occupational exposure to WAGs, this cross-sectional study is the first to jointly evaluate biomarkers of genetic instability, oxidative stress, and susceptibility genes in professionals occupationally exposed to high trace amounts of halogenated (≥ 7 ppm) and nitrous oxide (165 ppm) anesthetics in ORs and in individuals not exposed to WAGs (control group). Elevated rates of buccal micronucleus (MN) and nuclear bud (NBUD) were observed in the exposure group and in professionals exposed aged more than 30 years. Exposed males showed a higher antioxidant capacity, as determined by the ferric reducing antioxidant power (FRAP), than exposed females; exposed females had higher frequencies of MN and NBUD than nonexposed females. Genetic instability (MN) was observed in professionals with greater weekly WAG exposure, and those exposed for longer durations (years) exhibited oxidative stress (increased lipid peroxidation and decreased FRAP). Polymorphisms in metabolic genes (cytochrome P450 2E1 (CYP2E1) and glutathione S-transferases (GSTs)) did not exert an effect, except for the effects of the GSTP1 (rs1695) AG/GG polymorphism on FRAP (both groups) and GSTP1 AG/GG and GSTT1 null polymorphisms, which were associated with greater FRAP values in exposed males. Minimizing WAG exposure is necessary to reduce impacts on healthcare workers.

Association of glutathione S-transferases (GSTT1, GSTM1 and GSTP1) genes polymorphisms with nonalcoholic fatty liver disease susceptibility: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Glutathione S-transferases (GSTs) genes single-nucleotide polymorphisms (SNPs) have been connected with the susceptibility of nonalcoholic fatty liver disease (NAFLD), but with inconsistent results across the current evidences. The present work was schemed to explore the association between GSTs genes polymorphisms and the NAFLD vulnerability via meta-analysis.

METHODS

PubMed, Web of Science, Cochrane Library, China National Knowledge Infrastructure and Wanfang were retrieved for eligible literatures previous to March 10, 2021. The odds ratio (OR) of the dichotomic variables and the standardized mean difference of quantitative variables with corresponding 95% confidence intervals (95%CIs) were computed to evaluate the strength of the associations. The quality of included studies were assessed via using Newcastle-Ottawa Scale (NOS).

RESULTS

In total, 7 case-control studies encompassing 804 NAFLD patients and 1362 disease-free controls in this meta-analysis. Ultimately, this analysis included 6, 5 and 5 studies for GSTM1, GSTT1 and GSTP1 polymorphisms, respectively. The pooled data revealed that the GSTs genes SNPs had conspicuous associations with NAFLD susceptibility: for GSTM1, null versus present, OR = 1.46, 95%CI 1.20 to 1.79, P = .0002; for GSTT1, null versus present, OR = 1.34, 95%CI 1.06 to 1.68, P = .01; for GSTP1, Ile/Val or Val/Val versus Ile/Ile, OR = 1.60, 95%CI 1.23 to 2.09, P = .0005.

CONCLUSION

This work revealed that the GSTM1 null, GSTT1 null and GSTP1-Val genotypes might be related to increased NAFLD susceptibility.

GSTT1/GSTM1 Genotype and Anti-Tuberculosis Drug-Induced Hepatotoxicity in Peruvian Patients

In Peru, 24,581 people were diagnosed with tuberculosis (TB) in 2020. Although TB treatments are effective, 3.4–13% are associated with significant adverse drug reactions (ADRs), with drug-induced liver injury (DILI) considered the most predominant. Among the first-line antituberculosis drugs, isoniazid (INH) is the main drug responsible for the appearance of DILI. In the liver, INH is metabolized by the enzymes N-acetyltransferase-2 (NAT2), cytochrome P450 2E1 (CYP2E1), and glutathione S-transferase (GST) with two isoforms, GSTT1 and GSTM1. Based on previous studies, we hypothesized that interactions between the GSTT1 and GSTM1 null genotypes induce DILI in TB patients. In this cross-sectional study of 377 participants who completed their anti-TB treatment, we genotyped by revealing the presence or absence of 215- and 480-bp bands of GSTM1 and GSTT1, respectively. We found that the prevalence of the GSTM1 genotype was 52.79% and 47.21% for presence and null, respectively, and for GSTT1 it was 69.76% and 30.24% for presence and null, respectively. Neither genotype was prevalent in the patients who developed DILI (n = 16). We did not confirm our hypothesis; however, we found that the combination of GSTM1 present genotype, GSTT1 null genotype, fast NAT2 acetylators, and CYP2E1 c1/c1 genotype had a significant risk for the development of ADR (OR 11; p = 0.017; 95% CI: (0.54–186.35)). We propose that the presence of the GSTM1 present genotype, GSTT1 null genotype, fast NAT2 acetylators, and CYP2E1 c1/c1 genotype in the Peruvian population could be considered a risk factor for the development of ADR due to therapeutic drug intake.

Host polymorphisms and COVID-19 infection

Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). There is growing evidence that host genetics play an important role in COVID-19 severity. Based on current knowledge about the human protein machinery for SARS-CoV-2 entry, the host innate immune response, and virus-host interactions, the potential effects of human genetic polymorphisms, which may contribute to clinical differences in SARS-CoV-2 pathogenesis, may help to determine the individual risk for COVID-19 infection and outcome.

The Role of Glutathione-S Transferase in Psoriasis and Associated Comorbidities and the Effect of Dimethyl Fumarate in This Pathway

Psoriasis vulgaris is a chronic inflammatory skin disease characterized by well-demarcated scaly plaques. Oxidative stress plays a crucial role in the psoriasis pathogenesis and is associated with the disease severity. Dimethyl fumarate modulates the activity of the pro-inflammatory transcription factors. This is responsible for the downregulation of inflammatory cytokines and an overall shift from a pro-inflammatory to an anti-inflammatory/regulatory response. Both steps are necessary for the amelioration of psoriatic inflammation, although additional mechanisms have been proposed. Several studies reported a long-term effectiveness and safety of dimethyl fumarate monotherapy in patients with moderate-to-severe psoriasis. Furthermore, psoriasis is a chronic disease often associated to metabolic comorbidities, as obesity, diabetes, and cardiovascular diseases, in which glutathione-S transferase deregulation is present. Glutathione-S transferase is involved in the antioxidant system. An increase of its activity in psoriatic epidermis in comparison with the uninvolved and normal epidermal biopsies has been reported. Dimethyl fumarate depletes glutathione-S transferase by formation of covalently linked conjugates. This review investigates the anti-inflammatory role of dimethyl fumarate in oxidative stress and its effect by reducing oxidative stress. The glutathione-S transferase regulation is helpful in treating psoriasis, with an anti-inflammatory effect on the keratinocytes hyperproliferation, and in modulation of metabolic comorbidities.

Genetic polymorphism of glutathione S-transferases (GSTM1, GSTT1, and GSTP1) in patients with bullous pemphigoid in a Polish population

Introduction. Bullous pemphigoid (BP) is one of the most common bullous diseases with an autoimmune background. The etiology and pathogenesis of BP are believed to be influenced not only by environmental, genetic, and immunological factors as well as by oxidative stress. BP is observed more frequently in elderly patients. Additionally, more potent oxidative stress is observed just in old age. Glutathione S-transferases (GSTs) play key roles in the detoxification of xenobiotics, metabolism of endogenous substrates, and the defense against oxidative stress. The present study examines whether polymorphism of genes encoding three selected GSTs (GSTM1, GSTT1, and GSTP1) might be associated with a higher risk for BP.

Materials and methods. The study involved 71 patients with BP and 100 healthy volunteers from a Polish population. The presence of the deletion type polymorphism for GSTM1 and GSTT1 was confirmed by multiplex PCR. The Ile105Val GSTP1 polymorphism was analyzed by PCR-RFLP.

Results. It was observed that the combination of GSTM1 null/GSTT1 null/GSTP1 Ile/Val, Val/Val genotypes occurred more frequently in patients with BP (8.5%) than in controls (4.0%). The odds ratio for carriers of GSTM1 null/GSTT1 null/ GSTP1 Ile/Val, Val/Val genotypes was 2.22 (95% CI 0.60–8.16; p = 0.3727), but was not statistically significant.

Conclusions. The combination of GSTM1 null, GSTT1 null, GSTP1 Ile/Val, Val/Val genotypes might be related to a greater risk of BP in a Polish population. However, future studies including more individuals are required to confirm this.

Drug-oxidizing and conjugating non-cytochrome P450 (non-P450) enzymes in cynomolgus monkeys and common marmosets as preclinical models for humans

Many drug oxidations and conjugations are mediated by a variety of cytochromes P450 (P450) and non-P450 enzymes in humans and non-human primates. These non-P450 enzymes include aldehyde oxidases (AOX), carboxylesterases (CES), flavin-containing monooxygenases (FMO), glutathione S-transferases (GST), arylamine N-acetyltransferases (NAT),sulfotransferases (SULT), and uridine 5'-diphospho-glucuronosyltransferases (UGT) and their substrates include both endobiotics and xenobiotics. Cynomolgus macaques (Macaca fascicularis, an Old-World monkey) are widely used in preclinical studies because of their genetic and physiological similarities to humans. However, many reports have indicated the usefulness of common marmosets (Callithrix jacchus, a New World monkey) as an alternative non-human primate model. Although knowledge of the drug-metabolizing properties of non-P450 enzymes in non-human primates is relatively limited, new research has started to provide an insight into the molecular characteristics of these enzymes in cynomolgus macaques and common marmosets. This mini-review provides collective information on the isoforms of non-P450 enzymes AOX, CES, FMO, GST, NAT, SULT, and UGT and their enzymatic profiles in cynomolgus macaques and common marmosets. In general, these non-P450 cynomolgus macaque and marmoset enzymes have high sequence identities and similar substrate recognitions to their human counterparts. However, these enzymes also exhibit some limited differences in function between species, just as P450 enzymes do, possibly due to small structural differences in amino acid residues. The findings summarized here provide a foundation for understanding the molecular mechanisms of polymorphic non-P450 enzymes and should contribute to the successful application of non-human primates as model animals for humans.

Effect of glutathione S-transferase gene polymorphisms on semen quality in patients with idiopathic male infertility

OBJECTIVE

To investigate the relationship between glutathione S-transferase enzyme (GSTM1, T1, and P1) genetic variants and semen quality in men with idiopathic infertility.

METHODS

Sperm characteristics were measured using computer-assisted sperm analysis. The malondialdehyde (MDA), nitric oxide (NO), and total antioxidant capacity (TAC) activities were detected by spectroscopic analysis, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) was detected by enzyme-linked immunosorbent assay.

RESULTS

This study included 246 idiopathic infertile men and 117 controls. The GSTM1(-), T1(-), and M1/T1(-/-) genotype frequencies significantly differed between the groups. The GSTM1(-) and T1(-) genotypes in idiopathic infertile men negatively correlated with sperm concentration, motility, mitochondrial membrane potential, and other parameters. However, these genotypes positively correlated with the amplitude of the lateral head displacement and NO and 8-OHdG levels. The GSTT1(-) genotype positively correlated with mean angular displacement and MDA activity. GSTM1(-) and T1(-) had a synergistic effect on semen quality. Sperm motility, normal morphology, straightness, and TAC were lower and amplitude of lateral head displacement and MDA were higher in the GSTP1(A/G + G/G) group than in the GSTP1(A/A) group among men with idiopathic infertility.

CONCLUSIONS

GSTM1, T1, and P1 genetic variants may be risk factors for infertility by affecting the semen quality men with idiopathic oligoasthenospermia.

COVID-19 Modulates Inflammatory and Renal Markers That May Predict Hospital Outcomes among African American Males

Background and Objectives: African Americans and males have elevated risks of infection, hospitalization, and death from SARS-CoV-2 in comparison with other populations. We report immune responses and renal injury markers in African American male patients hospitalized for COVID-19. Methods: This was a single-center, retrospective study of 56 COVID-19 infected hospitalized African American males 50+ years of age selected from among non-intensive care unit (ICU) and ICU status patients. Demographics, hospitalization-related variables, and medical history were collected from electronic medical records. Plasma samples collected close to admission (≤2 days) were evaluated for cytokines and renal markers; results were compared to a control group (n = 31) and related to COVID-19 in-hospital mortality. Results: Among COVID-19 patients, eight (14.2%) suffered in-hospital mortality; seven (23.3%) in the ICU and one (3.8%) among non-ICU patients. Interleukin (IL)-18 and IL-33 were elevated at admission in COVID-19 patients in comparison with controls. IL-6, IL-18, MCP-1/CCL2, MIP-1α/CCL3, IL-33, GST, and osteopontin were upregulated at admission in ICU patients in comparison with controls. In addition to clinical factors, MCP-1 and GST may provide incremental value for risk prediction of COVID-19 in-hospital mortality. Conclusions: Qualitatively similar inflammatory responses were observed in comparison to other populations reported in the literature, suggesting non-immunologic factors may account for outcome differences. Further, we provide initial evidence for cytokine and renal toxicity markers as prognostic factors for COVID-19 in-hospital mortality among African American males.

The Investigation of Metabonomic Pathways of Serum of Iranian Women with Recurrent Miscarriage Using 1H NMR

Purpose

Recurrent miscarriage applies to pregnancy loss expulsion of the fetus within the first 24 weeks of pregnancy. This study is aimed at comparatively investigating the sera of women with RM with those who have no record of miscarriages to identify if there were any metabolite and metabolic pathway differences using ¹H NMR spectroscopy.

Methods

Serum samples were collected from women with RM (n = 30) and those who had no records of RM (n = 30) to obtain metabolomics information. ¹H NMR spectroscopy was carried out on the samples using Carr Purcell Meiboom Gill spin echo; also, Partial Least Squares Discriminant Analysis was performed in MATLAB software using the ProMetab program to obtain the classifying chemical shifts; the metabolites were identified by using the Human Metabolome Database (HMDB) in both the experimental and control groups. The pathway analysis option of the Metaboanalyst.ca website was used to identify the changed metabolic pathways.

Results

The results of the study revealed that 14 metabolites were different in the patients with RM. Moreover, the pathway analysis showed that taurine and hypotaurine metabolism along with phenylalanine, tyrosine, and tryptophan biosynthesis was significantly different in patients with RM.

Conclusion

The present study proposes that any alteration in the above metabolic pathways might lead to metabolic dysfunctions which may result in a higher probability of RM.

Susceptibility of Glutathione--S-Transferase Polymorphism to CVD Development in Type 2 Diabetes Mellitus - A Review

BACKGROUND

Metabolic disorder affects normal homeostasis and can lead to the development of diseases. Diabetes mellitus is the most common metabolic disorder, and a cluster of metabolic conditions can lead to cardiovascular disease (CVD) development. Diabetes mellitus and CVD are closely related, with oxidative stress, playing a major role in the pathophysiology. Glutathione-S-Transferases (GST) potentially play an important role by reducing oxidative stress and is found to be the underlying pathophysiology in the development of diabetes, cardiovascular diseases (CVD), etc. Objectives: In this review, the role of GST genetic variant in the development of diabetes mellitus, CVD and diabetic vascular complications has been focused.

RESULTS

Based on the literature, it is evident that the GST can act as an important biochemical tool providing significant evidence regarding oxidative stress predominant in the development of diseases. Analysis of GST gene status, particularly detection of GSTM1 and GSTT1 null mutations and GSTP1 polymorphism, have clinical importance.

CONCLUSION

The analysis of GST polymorphism may help identify the people at risk and provide proper medical management. Genotyping of GST gene would be a helpful biomarker for early diagnosis of CVD development in DM and also in CVD cases. More studies focusing on the association of GST polymorphism with CVD development in diabetic patients will help us determine the pathophysiology better.

Association of GSTM1 and GSTT1 gene polymorphisms with COVID-19 susceptibility and its outcome

Coronavirus disease 2019 (COVID‐19) caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection has become a global health issue and develops into a broad range of illnesses from asymptomatic to fatal respiratory diseases. SARS‐CoV‐2 infection is associated with oxidative stress that triggers cytokine production, inflammation, and other pathophysiological processes. Glutathione‐S‐transferase (GST) is an important enzyme that catalyzes the conjugation of glutathione (GSH) with electrophiles to protect the cell from oxidative damage and participates in the antioxidant defense mechanism in the lungs. Thus, in this study, we investigated the role of GSTM1 and GSTT1 gene polymorphism with COVID‐19 susceptibility, as well as its outcome. The study included 269 RT‐PCR confirmed COVID‐19 patients with mild (n = 149) and severe (n = 120) conditions. All subjects were genotyped for GSTM1 and GSTT1 by multiplex polymerase chain reaction (mPCR) followed by statistical analysis. The frequency of GSTM1^−/−, GSTT1^−/− and GSTM1^−/−/GSTT1^−/− was higher in severe COVID‐19 patients as compared to mild patients but we did not observe a significant association. In the Cox hazard model, death was significantly 2.28‐fold higher in patients with the GSTT1^−/− genotype (p = 0.047). In combination, patients having GSTM1^+/+ and GSTT1^−/− genotypes showed a poor survival rate (p = 0.02). Our results suggested that COVID‐19 patients with the GSTT1^−/− genotype showed higher mortality.

Mutations and polymorphisms in genes involved in the infections by covid 19: a review

Covid19 is the third most aggressive coronavirus that spreads rapidly and kills many people. It is a multigenic and multifactorial disease with many genetic and environmental determinants. The identification of these factors is key to better understanding the etiology of Covid-19 and it can also help predict the risk and prevent Covid-19 infection. Many predisposing factors have been described for this coronavirus such as advanced age, male gender, and geographic location. In addition to these elements, genetic factors have an important role in Covid19 infection. Interindividual variation in susceptibility to infection by Covid-19 has been associated with to the presence of genetic polymorphisms in many genes, especially in those that code for proteins implicated in the infection process. The present review gives a brief overview of different genes involved in the infection by SARS-CoV-2 and its association with disease severity. The results of our research showed that many different genes are associated with a higher risk for COVID-19, notably those coding for proteins involved in coronavirus-cell entry and fusion such as ACE2 (angiotensin I converting enzyme 2), TMPRSS2 (transmembrane protease, serine 2) and CD26.

Association of xenobiotic-metabolizing enzymes (GSTM1 and GSTT 1), and pro-inflammatory cytokines (TNF-α and IL-6) genetic polymorphisms with non-alcoholic fatty liver disease

Previous studies have revealed that genetic polymorphisms of the Glutathione S-transferase M1 and T1 (GSTM1 and GSTT1), tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) are associated with the presence of non-alcoholic fatty liver disease (NAFLD) in many populations. This study was conducted to investigate the association of the GSTM1, GSTT1, TNF-α rs1800629, and IL-6 rs1800795 with NAFLD in the general Iranian population. A case-control analysis included 242 NAFLD patients and 324 healthy controls from Iranian adults. After the physical examination, the genotypes were determined by polymerase chain reaction(PCR). The GSTM1 null, GSTT1 null, TNF-α AG/AA, and IL-6 CG/CC genotypes were deemed to be high-risk. The null allele of GSTM1 and A allele of TNF-α were more frequent in NAFLD patients even after Bonferroni's correction (P values<0.005, adjusted odds ratio (OR), 1.66 and 2.02; 95% confidence intervals (CI), (1.18-2.32) and (1.34-3.34), respectively. The IL-6 CC/CG genotype association with NAFLD was not significant after correction (P value = 0.04) Polymorphisms of xenobiotic and pro-inflammatory genes are associated with NAFLD in the Iranian population and seem to be a useful tool for NAFLD prevention and care.

Secondary Genome-Wide Association Study Using Novel Analytical Strategies Disentangle Genetic Components of Cleft Lip and/or Cleft Palate in 1q32.2

Orofacial cleft (OFC) is one of the most prevalent birth defects, leading to substantial and long-term burdens in a newborn's quality of life. Although studies revealed several genetic variants associated with the birth defect, novel approaches may provide additional clues about its etiology. Using the Center for Craniofacial and Dental Genetics project data (n = 10,542), we performed linear mixed-model analyses to study the genetic compositions of OFC and investigated the dependence among identified loci using conditional analyses. To identify genes associated with OFC, we conducted a transcriptome-wide association study (TWAS) based on predicted expression levels. In addition to confirming the previous findings at four loci, 1q32.2, 8q24, 2p24.2 and 17p13.1, we untwined two independent loci at 1q32.2, TRAF3IP3 and IRF6. The sentinel SNP in TRAF3IP3 (rs2235370, p-value = 5.15 × 10^-9) was independent of the sentinel SNP at IRF6 (rs2235373, r² < 0.3). We found that the IRF6 effect became nonsignificant once the 8q24 effect was conditioned, while the TRAF3IP3 effect remained significant. Furthermore, we identified nine genes associated with OFC in TWAS, implicating a glutathione synthesis and drug detoxification pathway. We identified some meaningful additions to the OFC etiology using novel statistical methods in the existing data.

Paracetamol-Induced Glutathione Consumption: Is There a Link With Severe COVID-19 Illness?

COVID-19 pandemic is posing an unprecedented sanitary threat: antiviral and host-directed medications to treat the disease are urgently needed. A great effort has been paid to find drugs and treatments for hospitalized, severely ill patients. However, medications used for the domiciliary management of early symptoms, notwithstanding their importance, have not been and are not presently regarded with the same attention and seriousness. In analogy with other airways viral infections, COVID-19 patients in the early phase require specific antivirals (still lacking) and non-etiotropic drugs to lower pain, fever, and control inflammation. Non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol (PAC) are widely used as non-etiotropic agents in common airways viral infections and hence are both theoretically repurposable for COVID-19. However, a warning from some research reports and National Authorities raised NSAIDs safety concerns because of the supposed induction of angiotensin-converting enzyme 2 (ACE2) levels (the receptor used by SARS-CoV2 to enter host airways cells), the increased risk of bacterial superinfections and masking of disease symptoms. As a consequence, the use of NSAIDs was, and is still, discouraged while the alternative adoption of paracetamol is still preferred. On the basis of novel data and hypothesis on the possible role of scarce glutathione (GSH) levels in the exacerbation of COVID-19 and of the GSH depleting activity of PAC, this commentary raises the question of whether PAC may be the better choice.

Activation of the Nrf2 response by oleanolic acid oxime morpholide (3-hydroxyiminoolean-12-en-28-oic acid morpholide) is associated with its ability to induce apoptosis and inhibit proliferation in HepG2 hepatoma cells

Our previous study demonstrated that new oleanolic acid oxime (OAO) derivatives and their conjugates with aspirin (ASP) inhibit NF-κB activation. Evidence exists that the downregulation of NF-κB negatively interferes with the Nrf2 signaling pathway. This study aimed to evaluate the effect of these compounds on Nrf2 activation and its cellular consequences in human hepatoma HepG2 cells and immortalized normal hepatocytes THLE-2. The results showed the enhanced activation and expression of Nrf2 as a result of treatment with OAO derivatives themselves and to less extent by their ASP conjugates, mainly in HepG2 cells. The association between cytotoxicity evaluated in our previous study and Nrf2 activation was observed. In this regard, compounds (18) with morpholide substituent at the C-17 position of OAO molecule and (12) with methyl ester substituent at the same position of OAO molecule to the most extent activated Nrf2 and subsequently cell cycle arrest at G2/M, leading to increased apoptosis and the number of resting HepG2 cells. The derivative of OAO (18) substituted with ASP (19) also affected Nrf2 activation and expression, but this effect was less pronounced in comparison with non-conjugated OAO. However, conjugation enhanced Nrf2 activation in normal THLE-2 cells. These results confirmed our earlier suggestion that OAO derivatives conjugated with ASP have the potential for application in the liver cancer chemoprevention. OAO themselves, particularly OAO substituted with morpholide, may be considered therapeutic agents, which may support conventional treatment strategy. Further studies are required to confirm this suggestion.

Association of Genetic Polymorphisms in GSTP1, GSTM1, and GSTT1 Genes with Vesicoureteral Reflux Susceptibility in the Children of Southeast Iran

Background:

Vesicoureteral reflux (VUR) disease is the most common type of urinary tract anomalies in children. Genetic risk factors may be associated with the etiology of VUR. The role of the Glutathione S-transferases (GSTs) as multifunctional enzymes is cellular oxidative stress handling. This is the first study aimed at evaluating the relative risk of GSTP1, GSTM1, and GSTT1 polymorphisms in VUR susceptibility in children and provides new important insights into the genetics of affected children.

Methods:

The study was done in 2013 in Sistan and Baluchestan University, eastern Iran. Genotyping of three GSTP1, GSTM1, and GSTT1 genes were determined using the multiplex polymerase chain reaction assay in 216 reactions for 72 VUR children and 312 reactions for 104 healthy controls.

Results:

The presence of GSTT1 deletion was associated with high risk of VUR in children, whereas GSTP1 and GSTM1 genotypes did not show the same effect. Furthermore, the combination of GSTT1/GSTM1 and GSTT1/ GSTP1 genotypes showed a significant influence on lower risk of VUR in children.

Conclusion:

Deletion of GSTT1 functional gene is a genetic risk factor causing VUR in children. Interestingly, the combination of GSTM1 and GSTP1 null genotypes with GSTT1 has shown a protective role against risk of GSTT1 deletion.

GSTM1-null allele predicts rapid disease progression in nondialysis patients and mortality among South Indian ESRD patients

Chronic kidney disease (CKD) is one of the main causes of early death in humans worldwide. Glutathione S-Transferases (GSTs) are involved in a series of xenobiotics metabolism and free radical scavenging. The previous studies elucidated the interlink between GST variants and to the development of various diseases. The present case-control study performed to ascertain whether GST polymorphisms are associated with the incidence and advancement of CKD. From the Southern part of India, a total of 392 CKD patients (nondialysis, ND; n = 170, end-stage renal disease, ESRD; n = 222) and 202 healthy individuals were enrolled. Patients were followed-up for 70 months. Serum biochemical parameters were recorded, and the extraction of DNA was done from the patient's blood samples. To genotype study participants, multiplex PCR for GSTM1/T1 was performed. Statistical analysis was carried out to analyze the relationship between gene frequency and sonographic grading, as well as biochemical parameters for disease development. The GSTM1-null genotype showed threefold increased risk (OR = 2.9304; 95% CI 1.8959 to 4.5296; P < 0.0001) to CKD development and twofold increased risk (OR = 1.8379; 95% CI 1.1937 to 2.8299; P = 0.0057) to ESRD progression. During the mean follow-up of 41 months study, multivariate Cox regression analysis revealed that GSTM1-null genotype has 4 times increased the risk for all-cause rapid disease progression to ESRD among ND patients and 3.85-fold increased risk for death among ESRD patients. Survival analysis revealed that patients with GSTM1-present allele showed a significantly diminished risk of mortality compared to patients bearing the GSTM1-null allele among ESRD patients with a hazard ratio of 4.6242 (P < 0.0001). Thus, present data confirm that GSTM1-null genotype increased the risk for all-cause rapid disease progression to ESRD among ND patients. Based on our results, GSTM1-null genotype could be considered as a significant predictor for causing mortality among CKD patients when compared to all other variables.

GSTP1 and cancer: Expression, methylation, polymorphisms and signaling (Review)

Glutathione S‑transferase Pi (GSTP1) is an isozyme encoded by the GST pi gene that plays an important regulatory role in detoxification, anti‑oxidative damage, and the occurrence of various diseases. The aim of the present study was to review the association between the expression of GSTP1 and the development and treatment of various cancers, and discuss GSTP1 methylation in several malignant tumors, such as prostate, breast and lung cancer, as well as hepatocellular carcinoma; to review the association between polymorphism of the GSTP1 gene and various diseases; and to review the effects of GSTP1 on electrophilic oxidative stress, cell signal transduction, and the regulation of carcinogenic factors. Collectively, GSTP1 plays a major role in the development of various diseases.

Systematic characterization of glutathione S-transferases in common marmosets

The common marmoset is an important primate species used in drug metabolism studies. However, glutathione S-transferases (GSTs), essential drug-metabolizing enzymes involved in the conjugation of various endogenous and exogenous substrates, have not been identified or characterized in this species. In this study, 20 GSTs [including 3 microsomal GSTs (MGSTs)] were identified and characterized in marmosets. Marmoset GSTs had amino acid sequences highly identical (86-99%) to human GSTs, except for GSTA4L, which had lower identities (59-62%) with human GSTAs. Phylogenetic analysis revealed that marmoset GSTs were closely clustered with their human counterparts. Marmoset GSTs had gene and genomic structures generally similar to their human counterparts, with some differences in GSTA, GSTM, and GSTT clusters. Marmoset GST mRNAs exhibited distinct tissue expression patterns: GSTA1, GSTA3, GSTA4L, GSTK1, GSTT1, GSTZ1, and MGST1 mRNAs were expressed most abundantly in liver. Other GST mRNAs were expressed most abundantly in small intestine, lung, brain, or kidney. Expression of GSTT4 and GSTT4L mRNAs was detected only in testis. Among all 20 marmoset GST mRNAs, the most abundant mRNAs were GSTA1 mRNA in liver, small intestine, and kidney; GSTM3 mRNA in testis; and MSGT3 mRNA in brain and lung. All 20 GSTs mediated the conjugation of GST substrates 1-chloro-2,4-dinitrobenzene; 1,2-epoxy-3-(p-nitrophenoxy)propane; styrene 7,8-oxide; and/or 1-iodohexane, but with different activity levels. Kinetic analyses showed that marmoset GSTM2/GSTM5 and GSTM5/GSTT1 effectively conjugated styrene 7,8-oxide and 1-iodohexane, respectively, with the highest affinity. These results suggest that the 20 newly identified marmoset GSTs were functional drug-metabolizing enzymes able to conjugate typical GST substrates.

Dual roles of glutathione S-transferase mu 1 in the development and metastasis of hepatocellular carcinoma

PURPOSE

Reactive oxygen species (ROS) are implicated in carcinogenesis, and cellular antioxidant systems are important for detoxifying ROS and reversing oxidant-mediated modifications. Glutathione S-transferase mu (GSTM) belongs to a family of phase II detoxification enzymes that catalyze the conjugation of reduced glutathione (GSH) to a wide range of endogenous and exogenous electrophilic compounds. The genotype of GSTM1 was associated with the risk and prognosis of cancer in several meta-analyses. This study explored the function of GSTM1 in hepatocellular carcinoma (HCC).

METHODS

Polymerase chain reaction (PCR) and western blotting (WB) were used to detect the levels of gene and protein expression. MTS assays, Transwell assays, and flow cytometry were used to explore the function of GSTM1 in vitro. The xenograft assay and tail vein injection model were used to explore the function of GSTM1 in vivo.

RESULTS

The mRNA and protein expression of GSTM1 was downregulated in HCC, but the expression levels of GSTM1 were not correlated with patient survival time. In vitro, Transwell and doxorubicin (DOX)-induced apoptosis assays revealed that GSTM1 showed opposite functions in different HCC cell lines with varied TP53 genotype statuses. The overexpression of GSTM1 in the above cell lines led to a significant decrease in ROS and an increase in GSH concentration and TP53 levels, suggesting that the controversial role of GSTM1 resulted from the TP53 genotype of HCC cells. The overexpression of GSTM1 promoted cell migration and inhibited apoptosis in the MHCC-97H cell line (TP53, R249S), but inhibited cell migration and increased apoptosis in the SMMC-7721 cell line (TP53 wildtype).

CONCLUSION

GSTM1 down-regulation may partially account for ROS-mediated oxidative damage and HCC carcinogenesis. GSTM1 also regulates tumor progression by disrupting the ROS-TP53 axis in HCC cells with different genetic backgrounds.

Ecogenetics of lead toxicity and its influence on risk assessment

Lead (Pb) toxicity is a public health problem affecting millions worldwide. Advances in 'omic' technology have paved the way to toxico-genomics which is currently revolutionizing the understanding of interindividual variations in susceptibility to Pb toxicity and its functional consequences to exposure. Our objective was to identify, comprehensively analyze, and curate all the potential genetic and epigenetic biomarkers studied to date in relation to Pb toxicity and its association with diseases. We screened a volume of research articles that focused on Pb toxicity and its association with genetic and epigenetic signatures in the perspective of occupational and environmental Pb exposure. Due to wide variations in population size, ethnicity, age-groups, and source of exposure in different studies, researchers continue to be skeptical on the topic of the influence of genetic variations in Pb toxicity. However, surface knowledge of the underlying genetic factors will aid in elucidating the mechanism of action of Pb. Moreover, in recent years, the application of epigenetics in Pb toxicity has become a promising area in toxicology to understand the influence of epigenetic mechanisms such as DNA methylation, chromatin remodeling, and small RNAs for the regulation of genes in response to Pb exposure during early life. Growing evidences of ecogenetic understanding (both genetic and epigenetic processes) in a dose-dependent manner may help uncover the mechanism of action of Pb and in the identification of susceptible groups. Such studies will further help in refining uncertainty factors and in addressing risk assessment of Pb poisoning.

Esophageal cancer genetics in South Africa

Esophageal cancer (EC) is an extremely aggressive cancer with one of the highest mortality rates. The cancer is generally only diagnosed at the later stages and has a poor 5-year survival rate due to the limited treatment options. China and South Africa are two countries with a very high prevalence rate of EC. EC rates in South Africa have been on the increase, and esophageal squamous cell carcinoma is the predominant subtype and a primary cause of cancer-related deaths in the black and male mixed ancestry populations in South Africa. The incidence of EC is highest in the Eastern Cape Province, especially in the rural areas such as the Transkei, where the consumption of foods contaminated with Fusarium verticillioides is thought to play a major contributing role to the incidence of EC. China is responsible for almost half of all new cases of EC globally. In China, the prevalence of EC varies greatly. However, the two main areas of high prevalence are the southern Taihang Mountain area (Linxian, Henan Province) and the north Jiangsu area. In both countries, environmental toxins play a major role in increasing the chance that an individual will develop EC. These associative factors include tobacco use, alcohol consumption, nutritional deficiencies and exposure to environmental toxins. However, genetic polymorphisms also play a role in predisposing individuals to EC. These include single-nucleotide polymorphisms that can be found in both protein-coding genes and in non-coding sequences such as miRNAs. The aim of this review is to summarize the contribution of genetic polymorphisms to EC in South Africa and to compare and contrast this to the genetic polymorphisms observed in EC in the most comprehensively studied population group, the Chinese.

Age- and gender-independent association of glutathione S-transferase null polymorphisms with chronic myeloid leukemia

The glutathione S-transferase (GST) genes encode enzymes that mediate the detoxification of xenobiotics by catalyzing the conjugation of glutathione (GSH) to xenobiotic substrates. The aim of the current study is to investigate the association between GSTT1 and GSTM1 polymorphisms and chronic myeloid leukemia (CML) among Sudanese patients. Patients with CML (n = 115) were recruited to the study from the Radiation and Isotope Centre Khartoum (RICK)-Sudan. Healthy individuals (n = 104) were included as controls. Genotyping of GSTT1 and GSTM1 polymorphisms was performed using multiplex PCR. Null deletions in the GSTT1 and GSTM1 genes are common in the Sudanese population (control group), with frequencies of 33.9% and 38.2%, respectively. The frequencies of GSTT1 (OR: 3.25, 95% CI: 1.87-5.65, p < 0.001) and GSTM1 (OR: 2.14, 95% CI: 1.25-3.67, p < 0.005) null genotypes were significantly higher in CML patients vs. controls. The distribution of GSTT1 and GSTM1 null polymorphisms was not different between male and female (p > 0.01) and young and old CML patients (p > 0.05). Hematological parameters were not affected by null polymorphisms in the patient group (p > 0.05). In addition, the frequency of GSTM1 null polymorphism was lower in advanced-phase CML patients compared to chronic-phase patients (p < 0.05). The GSTT1 and GSTM1 null polymorphisms are associated with CML among Sudanese patients, independently of their age and gender.

Effect of glutathione S-transferase genetic polymorphisms on busulfan pharmacokinetics and veno-occlusive disease in hematopoietic stem cell transplantation: A meta-analysis

This meta-analysis was conducted to derive an integrated conclusion about the influence of glutathione S-transferase (GST) genetic polymorphisms on busulfan pharmacokinetic (PK) parameters and veno-occlusive disease (VOD). Studies which analysed the effect of GST genetic polymorphisms on area under the curve (AUC), clearance (CL) or VOD were searched for and selected. A pooled analysis was conducted using Comprehensive Meta-Analysis programme. Nineteen studies were included in this meta-analysis. GSTA1*B and GSTM1 null genotypes significantly decreased CL_IV of busulfan (standardized difference in means (SDM) = -1.103; P = 0.019 and SDM = -0.418; P = 0.002, respectively). GSTA1*B significantly increased AUC_IV of busulfan (SDM = 0.832; P = 0.046), whereas GSTM1 did not (SDM = 0.155; P = 0.478). The PK parameters of oral busulfan did not differ according to GST genotype. GSTA1, GSTM1 and GSTP1 were not significantly associated with VOD occurrence. GSTA1 and GSTM1 genotypes affected CL_IV of busulfan, but only GSTA1 affected AUC_IV . There was no significant difference in the PK parameters of oral busulfan (CL_PO and AUC_PO ) and VOD when only GST genotypes were considered.

Genetic Variants of Glutathione S-Transferase GSTT1 and GSTT2 in Cynomolgus Macaques: Identification of GSTT Substrates and Functionally Relevant Alleles

Glutathione S-transferase (GST) is a family of important drug-metabolizing enzymes, conjugating endogenous and exogenous compounds. Genetic polymorphisms result in the inter-individual variability of GST activity in humans. Especially, human GSTT1 and GSTT2 null alleles are associated with toxicity and various cancers derived from chemicals. Cynomolgus macaque, a nonhuman primate species widely used in drug metabolism studies, has molecular and enzymatic similarities of GSTs to the human orthologs; however, genetic polymorphisms have not been investigated in this species. In this study, resequencing of GSTT1 and GSTT2 in 64 cynomolgus and 32 rhesus macaques found 15 nonsynonymous variants and 1 nonsense variant for GSTT1 and 15 nonsynonymous variants for GSTT2. Some of these GSTT variants were distributed differently in Indochinese and Indonesian cynomolgus macaques and rhesus macaques. For analysis of functional relevance of the GSTT variants, 1-iodohexane and dibromomethane were determined to be suitable substrates for cynomolgus GSTT1 and GSTT2. However, the conjugation activities were roughly correlated with GSTT protein levels immunochemically quantified in cynomolgus liver samples with no statistical significances, implying the contributions of the GST genetic variants. Among the GSTT1 variants identified, the animals carrying R76C and D125G mutations showed lower conjugation activities toward dibromomethane than those of the wild-type in liver cytosolic fractions. Moreover, the recombinant R76C/D125G and D125G GSTT variant proteins showed significantly lower 1-iodohexane or dibromomethane conjugation activities than those of the wild-type protein. Therefore, inter-animal variability of GSTT-dependent drug metabolism is at least partly accounted for by GSTT1 and possibly GSTT2 variants in cynomolgus and rhesus macaques.

Role of Glutathione S Transferase M1 and T1 Gene Polymorphism in Hepatitis B Related Liver Diseases and Cryptogenic Cirrhosis

BACKGROUND AND AIM

Progression of hepatitis B virus infection (HBV) might be affected by host genetic factors. The present study was undertaken to study the role of glutathione S-transferases (GST)-M1 and T1 gene polymorphisms in different stages of HBV infection: HBV inactive carrier, chronic hepatitis B and cirrhosis, and cryptogenic cirrhosis.

METHODS

The study population comprised of 170 subjects; 120 cases (HBV inactive carrier, n = 30; HBV related chronic hepatitis, n = 30; HBV related cirrhosis, n = 30; cryptogenic cirrhosis, n = 30) and 50 unrelated healthy adults without liver disease as controls. Analysis of GSTM1 and GSTT1 gene polymorphisms was done by multiplex polymerase chain reaction.

RESULTS

The GSTM1 null genotype was seen more commonly in hepatitis B cirrhosis (n = 21; 70%), chronic hepatitis B (n = 19; 63.33%) and cryptogenic cirrhosis (n = 17; 56.67%) as compared with inactive carrier (n = 9; 30%) and controls (n = 13; 26%). The GSTT1 null genotype was seen less frequently in all the groups, the observed frequencies were controls (n = 7; 14%), inactive carrier (n = 5; 16.67%), chronic hepatitis B (n = 8; 26.67%) and hepatitis B cirrhosis (n = 7; 23.33%). The difference of GSTM1 null genotype frequencies was statistically significant for hepatitis B cirrhosis vs. controls (P = 0.0002), chronic hepatitis B vs. controls (P = 0.002) and cryptogenic cirrhosis vs. controls (P = 0.01). The GSTT1 null genotype was not found to vary significantly between the groups.

CONCLUSION

The patients with GSTM1 null genotype are at risk of progression of liver disease as the frequency of GSTM1 null genotype was found to be significantly higher in chronic hepatitis B, hepatitis B cirrhosis and cryptogenic cirrhosis as compared with controls.

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.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

Detoxification genes polymorphisms in SIDS exposed to tobacco smoke

The best hypothesis to explain Sudden Infant Death Syndrome (SIDS) pathogenesis is offered by the "triple risk model", which suggests that an interaction of different variables related to exogenous stressors and infant vulnerability may lead to the syndrome. Environmental factors are triggers that act during a particular sensible period, modulated by intrinsic genetic characteristics. Although literature data show that one of the major SIDS risk factors is smoking exposure, a specific involvement of molecular components has never been highlighted. Starting from these observations and considering the role of GSTT1 and GSTM1 genes functional polymorphisms in the detoxification process, we analyzed GSTM1 and GSTT1 null genotype frequencies in 47 SIDS exposed to tobacco smoke and 75 healthy individuals. A significant association (p < .0001) between the GSTM1 null genotype and SIDS exposed to smoke was found. On the contrary, no association between GSTT1 polymorphism and SIDS was determined. Results indicated the contribution of the GSTM1 -/- genotype resulting in null detoxification activity in SIDS cases, and led to a better comprehension of the triple risk model, highlighting smoking exposure as a real SIDS risk factor on a biochemical basis.

Identification and replication of the interplay of four genetic high-risk variants for urinary bladder cancer

Little is known whether genetic variants identified in genome-wide association studies interact to increase bladder cancer risk. Recently, we identified two- and three-variant combinations associated with a particular increase of bladder cancer risk in a urinary bladder cancer case-control series (Leibniz Research Centre for Working Environment and Human Factors at TU Dortmund (IfADo), 1501 cases, 1565 controls). In an independent case-control series (Nijmegen Bladder Cancer Study, NBCS, 1468 cases, 1720 controls) we confirmed these two- and three-variant combinations. Pooled analysis of the two studies as discovery group (IfADo-NBCS) resulted in sufficient statistical power to test up to four-variant combinations by a logistic regression approach. The New England and Spanish Bladder Cancer Studies (2080 cases and 2167 controls) were used as a replication series. Twelve previously identified risk variants were considered. The strongest four-variant combination was obtained in never smokers. The combination of rs1014971[AA] near apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like 3A (APOBEC3A) and chromobox homolog 6 (CBX6), solute carrier family 1s4 (urea transporter), member 1 (Kidd blood group) (SLC14A1) exon single nucleotide polymorphism (SNP) rs1058396[AG, GG], UDP glucuronosyltransferase 1 family, polypeptide A complex locus (UGT1A) intron SNP rs11892031[AA] and rs8102137[CC, CT] near cyclin E1 (CCNE1) resulted in an unadjusted odds ratio (OR) of 2.59 (95% CI = 1.93-3.47; P = 1.87 × 10-10), while the individual variant ORs ranged only between 1.11 and 1.30. The combination replicated in the New England and Spanish Bladder Cancer Studies (ORunadjusted = 1.60, 95% CI = 1.10-2.33; P = 0.013). The four-variant combination is relatively frequent, with 25% in never smoking cases and 11% in never smoking controls (total study group: 19% cases, 14% controls). In conclusion, we show that four high-risk variants can statistically interact to confer increased bladder cancer risk particularly in never smokers.

Association of glutathione S-transferases M1, P1 and T1 variations and risk of late-onset Alzheimer's disease

OBJECTIVE

Late-onset Alzheimer's disease (AD) is a genetically heterogeneous neurodegenerative disorder. Associations of the glutathione S-transferases (GSTs) polymorphisms with the risk factors for AD have not been definitely confirmed. We investigated the association of GSTM1 and GSTT1 null deletion and GSTP1 313 A/G polymorphisms and the risk of AD in an Iranian population.

METHODS

The case group consisted of 280 individuals with AD and the control group included 168 age-matched healthy individuals. The genotyping of the GSTP1 polymorphism was determined by PCR-RFLP and the GSTM1 and GSTT1 deletions were done by multiplex PCR method.

RESULTS

The GSTP1 AG genotype was significantly lower (p = 0.005; OR = 0.57, 95% CI: 0.38-0.84) in the patients (41.1%) than the control group (56.5%). The GSTM1 null genotype was significantly higher (p < 0.001) in the patients (40.5%) than the control group (15.8%). The GSTT1 null genotype was significantly higher (p < 0.038) in the patients (31.2%) than the control group (21.5%). The patients homozygous for the GSTM1 and GSTT1 null alleles showed a 3.5 and 1.5-fold increased risk of AD, respectively. There were interaction between GSTP1 AG genotype and absence of APOE e4 allele (p = 0.001), as well as presence of APOE ε4 and GSTM1 null genotype (p < 0.0001).

CONCLUSION

These findings suggested that GSTM1 and GSTT1 null deletions may be associated with susceptibility to AD and people with APOE e4 and GSTM1 null deletion have a higher increased risk for Late-onset AD in Iranian population.

Recent advances in protein engineering and biotechnological applications of glutathione transferases

Glutathione transferases (GSTs, EC 2.5.1.18) are a widespread family of enzymes that play a central role in the detoxification, metabolism, and transport or sequestration of endogenous or xenobiotic compounds. During the last two decades, delineation of the important structural and catalytic features of GSTs has laid the groundwork for engineering GSTs, involving both rational and random approaches, aiming to create new variants with new or altered properties. These approaches have expanded the usefulness of native GSTs, not only for understanding the fundamentals of molecular detoxification mechanisms, but also for the development medical, analytical, environmental, and agricultural applications. This review article attempts to summarize successful examples and current developments on GST engineering, highlighting in parallel the recent knowledge gained on their phylogenetic relationships, structural/catalytic features, and biotechnological applications.