Genetic polymorphisms of glutathione S-transferase M1, T1, and P1, and the assessment of oxidative damage in infertile men with varicoceles from northwestern China

The Evolving Landscape of Male Varicocele Pathophysiology in the Era of Multi-Omics: A Narrative Review of the Current Literature

Male-factor infertility is implicated in over half of the millions of cases of infertility worldwide, and varicoceles are the most common correctable cause of male-factor infertility. The pathophysiologic mechanism for varicoceles is complex and next-generation technologies offer promising insights into the molecular underpinnings of this condition. In this narrative review, we highlight historical and contemporary paradigms associated with varicoceles, with an emphasis on the biological underpinnings of this disease. Specifically, we review the literature describing the underlying causes of varicoceles, discuss the molecular and cellular mechanisms causing pathological changes in some (but not all) men, and highlight key articles regarding the next-generation analyses (e.g., transcriptome, epigenome, proteome, and microbiome) being applied to better understand the condition and its treatment. These data demonstrate an ongoing evolution of the knowledge of varicoceles and the potential for improved personalized care in the future for men with this condition.

Genetic variants in varicocele-related male infertility: a systematic review and future directions

Genetic association studies (GAS) may have the capability to probe the genetic susceptibility alleles in many disorders. This systemic review aimed to assess whether an association exists between gene(s)/allelic variant(s), and varicocele-related male infertility (VRMI). This review included 19 GAS that investigated 26 genes in 1,826 men with varicocele compared to 2,070 healthy men, and 263 infertile men without varicocele. These studies focussed on candidate genes and relevant variants, with glutathione S-transferase gene being the most frequently studied (n = 5) followed by the nitric oxide synthase 3 (NOS3) gene (n = 3) and the phosphoprotein tyrosine phosphatase 1 gene (n = 2). In one study the genes for NAD(P)H quinone oxidoreductase 1, sperm protamine, human 8-oxoguanine DNA glycosylase 1, methylenetetrahydrofolate reductase, polymerase gamma, heat shock protein 90, mitochondrial DNA, superoxide dismutase 2, transition nuclear protein 1, and transition nuclear protein 2, were assessed. There is no clear indication that any of these polymorphisms are sturdily associated with VRMI. However, three studies established that the polymorphic genotype (GT + TT) for rs1799983 polymorphism of the NOS3 gene is more frequent in varicocele patients. Further endeavours such as standardising reporting, exploring complementary designs, and the use of GWAS technology are justified to help replicate these early findings.

GSTT1, an increased risk factor for prostate cancer in patients with metabolic syndrome

Background

Glutathione S‐transferase (GSTs) gene polymorphism and metabolic syndrome (Mets) are generally considered to be risk factors for prostate cancer (PCa). However, this conclusion is still controversial. There is a close relationship between GSTs gene polymorphism and Mets. We suspect that the effect of GSTs gene polymorphism and Mets on PCa may be the result of their joint action. As a result, the purpose of this study was to investigate the potential effect of GSTs gene polymorphism on PCa in patients with Mets.

Methods

We collected blood samples from 128 patients with PCa and 200 controls. The GSTs gene polymorphism was detected by polymerase chain reaction‐restriction fragment length polymorphism (PCR–RFLP). Age, characteristics of Mets, frequencies of GSTs gene polymorphism, total prostate volume (TPV), Gleason score, and prostate‐specific antigen (PSA) were recorded and analyzed.

Results

There were significant differences in BMI, TG, LDL‐C, FBG, SBP, DBP, and HDL‐C among the control group, N‐PCa group, and Mets‐PCa group (p < 0.05). GSTT1 null genotype (OR = 2.844, 95% CI: 1.791–4.517), GSTM1 null genotype (OR = 2.192, 95% CI: 1.395–3.446), and GSTP1 (A/G + G/G) genotype (OR = 2.315, 95% CI: 1.465–3.657) were associated with PCa susceptibility and malignancy. Only the GSTT1 null genotype in Mets patients was positively correlated with PCa.

Conclusions

Our study suggests that GSTs gene polymorphism may be a risk factor for PCa and can predict the susceptibility and malignancy of PCa. Secondly, in Mets patients, GSTT1 null genotype significantly increased the risk of PCa. GSTM1 null genotype and the effect of GSTP1 (AG + GG) on PCa were not significantly related to Mets.

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.

Association of Herpes simplex virus I&II infections with rs187084 SNP of TLR9 and male infertility

Since TLR9 recognises unmethylated CpG motifs in viral DNA, its polymorphisms may contribute to the susceptibility to Herpes simplex virus I&II infection. In the present study, to evaluate the role of rs187084 SNP (single nucleotide polymorphism) of TLR9 in Herpes simplex virus I&II infection and male infertility, 103 infertile and 27 fertile blood and semen samples were analysed. We assessed the micro and macro properties of semen specimens and the presence of HSV immunoglobulins. Tetra-primer ARMS PCR was used to detect SNP and to investigate the genotype distribution of TLR9-rs187084 SNPs, and the correlation between polymorphisms of TLR9 gene and male infertility. Moreover, the odds ratio (OR) and 95% confidence intervals were used to estimate the strength of the association. Based on our finding, a significant correlation was observed between HSV infection, agglutination and polymorphism (TT) under dominant (OR = 1.28, 95% CI = 0.94-1.75) and recessive (OR = 0.44, 95% CI = 0.21-0.94) models for the data, which was complied with Hardy-Weinberg equilibrium (HWE) (OR = 2.91, 95% CI = 1.02-8.30). The result showed a significant association between HSV IgM and agglutination in HSV infection (p < .001), and in addition, there were associations between alleles so that rs187084 SNP might be considered as a risk factor for the incidence of HSV infection.

Interaction of Blood Manganese Concentrations with GSTT1 in Relation to Autism Spectrum Disorder in Jamaican Children

Using data from 266 age- and sex-matched pairs of Jamaican children with autism spectrum disorder (ASD) and typically developing (TD) controls (2-8 years), we investigated whether glutathione S-transferase theta 1 (GSTT1) modifies the association between blood manganese concentrations (BMC) and ASD. After adjusting conditional logistic regression models for socioeconomic status and the interaction between GSTT1 and GSTP1 (glutathione S-transferase pi 1), using a recessive genetic model for GSTT1 and either a co-dominant or dominant model for GSTP1, the interaction between GSTT1 and BMC was significant (P = 0.02, P = 0.01, respectively). Compared to controls, ASD cases with GSTT1-DD genotype had 4.33 and 4.34 times higher odds of BMC > 12 vs. ≤ 8.3 μg/L, respectively. Replication in other populations is warranted.

The Sins of Our Forefathers: Paternal Impacts on De Novo Mutation Rate and Development

Spermatogonial stem cells (SSCs) are generally characterized by excellent DNA surveillance and repair, resulting in one of the lowest spontaneous mutation rates in the body. However, the barriers to mutagenesis can be overwhelmed under two sets of circumstances. First, replication errors may generate age-dependent mutations that provide the mutant cells with a selective advantage, leading to the clonal expansions responsible for dominant genetic diseases such as Apert syndrome and achondroplasia. The second mechanism centers on the vulnerability of the male germline to oxidative stress and the induction of oxidative DNA damage in spermatozoa. Defective repair of such oxidative damage in the fertilized oocyte results in the creation of mutations in the zygote that can influence the health and well-being of the offspring. A particular hot spot for such oxidative attack on chromosome 15 has been found to align with several mutations responsible for paternally mediated disease, including cancer, psychiatric disorders, and infertility.

Sperm DNA Fragmentation: A New Guideline for Clinicians

Sperm DNA integrity is crucial for fertilization and development of healthy offspring. The spermatozoon undergoes extensive molecular remodeling of its nucleus during later phases of spermatogenesis, which imparts compaction and protects the genetic content. Testicular (defective maturation and abortive apoptosis) and post-testicular (oxidative stress) mechanisms are implicated in the etiology of sperm DNA fragmentation (SDF), which affects both natural and assisted reproduction. Several clinical and environmental factors are known to negatively impact sperm DNA integrity. An increasing number of reports emphasizes the direct relationship between sperm DNA damage and male infertility. Currently, several assays are available to assess sperm DNA damage, however, routine assessment of SDF in clinical practice is not recommended by professional organizations. This article provides an overview of SDF types, origin and comparative analysis of various SDF assays while primarily focusing on the clinical indications of SDF testing. Importantly, we report four clinical cases where SDF testing had played a significant role in improving fertility outcome. In light of these clinical case reports and recent scientific evidence, this review provides expert recommendations on SDF testing and examines the advantages and drawbacks of the clinical utility of SDF testing using Strength-Weaknesses-Opportunities-Threats (SWOT) analysis.

Relation of nitric oxide synthase gene (NOS3) polymorphisms to varicocele risk and post-varicocelectomy seminal oxidative stress reduction

The pathophysiology of varicocele remains to be unknown. Several genetic factors have been implicated in varicocele etiopathogenesis. We studied the relationship between NOS3 c.894G>T, c.786T>C and 4b/a polymorphisms to varicocele risk and their prognostic value as regards improvement of the post-operative seminal parameters &/or seminal malonaldehyde levels. The three NOS3 polymorphisms were evaluated in 100 patients with varicocele and 100 healthy subjects by RT-PCR. Seminal plasma MDA level was measured pre-operatively and 3 months after varicocelectomy by the thiobarbituric acid method. The GT, TT, TC and bb genotypes of NOS3 polymorphism were more commonly observed in varicocele patients (30%, 9%, 28% and 70% respectively) compared to normal controls (12%, 0%, 10% and 50% respectively). The mean percentage of post-varicocelectomy seminal MDA reduction was highest with the GT genotype (p < .001). Genotypes GT+TT, TC and bb were associated with varicocele occurrence in our patients. The T (c.894G>T), C (c.786T>C) and b (NOS3 intron 4 VNTR) alleles were significantly associated with varicocele occurrence in our cohort of patients. We also report a better response regarding the reduction of seminal MDA after varicocelectomy with the GT and ba genotypes.

Influence of GSTP1 gene polymorhism on decreased semen quality

Background ― Genetic polymorphisms analysis of metabolic and antioxidant systems pathway genes are associated with male infertility is the most perspective and developed field in andrology. Purpose ― the aim of the research is to reveal the association of the glutathione S-transferase gene GSTP1 polymorphism C/T (rs1138272) with risk of pathospermia in Russian men in Moscow region. Material and Methods ― Case control study was conducted on 68 fertile men and 70 infertile men with various forms of pathospermia. Sperm analysis was performed according to WHO guidelines (WHO, 2010). DNA was extracted from peripheral blood leukocytes. Genotyping of the GSTP1 gene polymorphisms was carried out by generated amplicons from melting curve analysis after real time PCR. Results ― statistically significant association of polymorphism GSTP1 C/T (Ala/Val; rs1138272) with asthenozoospermia (χ2=8.58, p=0.003) and teratospermia (χ2=6.81, p=0.009) risk was found. The frequencies of homozygous and heterozygous carries (CT+TT genotypes) for polymorphic locus GSTP1 gene (rs1138272) are 3 times higher for men with disturbance of motility of spermatozoa and 2.5 times higher for men with abnormalities in morphology of spermatozoa, then for men with normozoospermia. Conclusion ― The GSTP1 C>T polymorphism (rs1138272) associated with risk of teratospermia and asthenozoospermia in male of reproductive age.

Glutathione-S-transferases M1/T1 gene polymorphisms and male infertility risk in Chinese populations: A meta-analysis

BACKGROUND

A meta-analysis was applied to evaluate the associations between the glutathione-S-transferases (GSTs) M1/T1 gene polymorphisms and male infertility in Chinese populations.

METHODS

A comprehensive search for articles was conducted from PubMed, Web of Science, Embase, China biology medical literature database (CBM), China National Knowledge Infrastructure (CNKI), VIP, and Chinese literature database(Wang fang) up to April 30, 2018. All of the statistical analyses were performed using Review Manager 5.3 and Stata 14.0.

RESULTS

Ten studies on GSTM1 gene polymorphism involving 3302 cases and 1959 controls, and ten studies on GSTT1 gene polymorphism involving 3048 cases and 1861 controls were included in this meta-analysis. Overall, the null genotype of GSTM1/GSTT1 was significantly related to male infertility risk in Chinese populations (GSTM1, OR = 1.35, 95% CI: 1.02-1.78; GSTT1, OR = 1.40, 95% CI: 1.15-1.70). In subgroup analyses stratified by infertility type, significant association was observed between GSTT1 null genotype and male infertility in both nonobstructive azoospermia (NOA) and oligoasthenozoospermia (OAT). However, the GSTM1 null genotype was associated with OAT, but not NOA in Chinese populations. The sensitivity analysis confirmed the reliability and stability of the meta-analysis.

CONCLUSION

Our meta-analysis supports that the GSTM1/GSTT1 null genotype might contribute to individual susceptibility to male infertility in Chinese populations.

Is male infertility associated with increased oxidative stress in seminal plasma? A-meta analysis

Objectives

We conducted a systematic review and meta-analysis of observational case-control studies to evaluate markers of oxidative stress in seminal plasma of patients with male infertility.

Background

Current evidence links oxidative stress to male infertility, in which multiple markers of oxidative stress have been widely detected, publishing inconsistent results with regard to the role of oxidative stress markers in the evaluation of male infertility. Therefore, a systematic review and meta-analysis on this issue is necessary.

Results

From the 1024 articles initially retrieved, 65 studies were included in our meta-analysis with 11 oxidative stress markers, containing 3819 male infertility patients and 2012 controls. The concentrations of malondialdehyde (SMD = 1.86, p < 0.00001), NO (SMD = 0.89, p = 0.001), carbonyl protein (SMD = 2.09, p < 0.00001) in seminal plasma were significantly higher in infertility patients. The concentrations of GSH (SMD = -1.68, p < 0.00001), vitamin C (SMD = -1.12, p < 0.00001), and vitamin E (SMD = -1.48, p = 0.003), as well as the activities of catalase (SMD = -1.91, p < 0.0001), glutathione peroxidase (SMD = -1.96, p = 0.0002) and glutathione-S-transferase (SMD = -1.62, p = 0.009) declined remarkably, resulting in decreased total antioxidant capacity (SMD = -1.77, p < 0.00001). Besides, the activity of superoxide dismutase showed no statistical difference between infertility patients and controls (SMD = -0.51, p = 0.07).

Conclusions

Our meta-analysis suggests that oxidative stress in seminal plasma resulting from decreased antioxidant defense are associated with male infertility.

Methods

Using PubMed, EMBASE, CNKI, VIP, and Wanfang database, we searched for literature reporting the detection of oxidative stress markers in the seminal plasma of male infertility published up to June 2017. Standardized mean differences (SMDs) and 95% confidence intervals (95%CI) were calculated for the finally analysis.

Lymphocyte DNA damage and plasma antioxidant status in Korean subclinical hypertensive patients by glutathione S-transferase polymorphism

BACKGROUND/OBJECTIVES

Glutathione S-transferase (GST) forms a multigene family of phase II detoxification enzymes which are involved in the detoxification of xenobiotics by conjugating substances with glutathione. The aim of this study is to assess the antioxidative status and the degree of DNA damage in the subclinical hypertensive patients in Korea using glutathione S-transferase polymorphisms.

SUBJECTS/METHODS

We examined whether DNA damage and antioxidative status show a difference between GSTM1 or GSTT1 genotype in 227 newly diagnosed, untreated (systolic blood pressure (BP) ≥ 130 mmHg or diastolic BP ≥ 85 mmHg) subclinical hypertensive patients and 130 normotensive subjects (systolic BP < 120 mmHg and diastolic BP < 80 mmHg). From the blood of the subjects, the degree of the DNA damage in lymphocyte, the activities of erythrocyte superoxide dismutase, the catalase, and the glutathione peroxidase, the level of glutathione, plasma total radical-trapping antioxidant potential (TRAP), anti-oxidative vitamins, as well as plasma lipid profiles and conjugated diene (CD) were analyzed.

RESULTS

Of the 227 subjects studied, 68.3% were GSTM1 null genotype and 66.5% were GSTT1 null genotype. GSTM1 null genotype had an increased risk of hypertension (OR: 2.104, CI: 1.38-3.35), but no significant association in GSTT1 null genotype (OR 0.982, CI: 0.62-1.55). No difference in erythrocyte activities of superoxide dismutase, catalase, or glutathione peroxidase, and plasma TRAP, CD, lipid profiles, and GSH levels were observed between GSTM1 or GSTT1 genotype. Plasma levels of α-tocopherol increased significantly in GSTT1 wild genotype (P < 0.05); however, plasma level of β-carotene increased significantly in GSTT1 null genotype (P < 0.01). DNA damage assessed by the Comet assay was significantly higher in GSTM1 null genotype than wild genotype (P < 0.05).

CONCLUSIONS

These results confirm the association between GSTM1 null genotype and risk of hypertension as they suggest that GSTM1 null genotype leads to an increased oxidative stress compared with wild genotype.

Genetics and epigenetics of varicocele pathophysiology: an overview

Varicocele is found in approximately 20% of adults and adolescents and in 19-41% of men seeking treatment for infertility. It is associated with a decrease in sperm count as well as sperm motility and morphology. The currently accepted description of the pathophysiology of varicocele does not explain all its clinical manifestations; therefore, other factors such as genetic and epigenetic changes, associated with the environment, might be involved in causing infertility and decrease in sperm quality. It has been reported that the varicocele-induced deterioration of testicular function is progressive and interferes with fertility; hence, early and efficient assessment of the genetic manifestations in patients would be important for developing future medical interventions. Chromosomal disorders, mutations, polymorphisms, changes in gene expression, and epigenetic changes have all been reported to be associated with varicocele. Several studies are underway to unravel the genetic basis of this disease, as it is important to understand the origin and the aggravating factors to ensure appropriate guidance and intervention. Here, we review the available literature regarding the genetic and epigenetic changes associated with varicocele, and how these alterations are related to the different clinical manifestations of the disease.

Glutathione S-transferase P1 Ile105Val Polymorphism and Male Infertility Risk: An Updated Meta-analysis

BACKGROUND

Several studies concerning the association between glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism and male infertility risk have reported controversial findings. The present study was aimed to explore this association using a meta-analysis.

METHODS

The PubMed, EMBASE, China National Knowledge Infrastructure (CNKI), and Wanfang databases were searched. Odds ratios (OR s) with 95% confidence intervals (CI s) were calculated to estimate the strength of the association.

RESULTS

A total of 3282 cases and 3268 controls in nine case-control studies were included. There was no significant association between GSTP1 Ile105Val polymorphism and male infertility in the overall population, but significant associations were found under the dominant (OR = 1.23, 95% CI = 1.04-1.46, I2 = 32.2%) and heterozygote (OR = 1.29, 95% CI = 1.08-1.53, I2 = 26.8%) models after excluding studies for which the data did not satisfy Hardy-Weinberg equilibrium (HWE). Similarly, subgroup analyses revealed no significant association in Asians or Chinese population although a significant association was apparent among Chinese population in studies with HWE under the heterozygote model (OR = 1.25, 95% CI = 1.03-1.52, I2 = 44.1%). Significant heterogeneity could be observed in some genetic models, but this heterogeneity was not significant when stratified by HWE. No evidence for publication bias was found.

CONCLUSIONS

The GSTP1 Ile105Val polymorphism might not be associated with male infertility risk, and thus additional well-designed studies with larger sample size are warranted.

Interactions between CYP2E1, GSTZ1 and GSTT1 polymorphisms and exposure to drinking water trihalomethanes and their association with semen quality

Trihalomethanes (THMs) have been reported to be associated with altered semen quality, and this association may be modified by inherited differences in cytochrome P450 (CYP2E1) and glutathione S-transferase (GSTZ1 and GSTT1), which metabolize THMs. We conducted a cross-sectional study to examine the interactions between CYP2E1, GSTZ1 and GSTT1 polymorphisms and exposure to THMs on semen quality among 401 men from the Reproductive Center of Tongji Hospital in Wuhan China. The baseline blood concentrations of four individual THMs, chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (TBM), were measured as biomarkers of exposure to drinking water THMs. Genotypes were determined by real-time PCR, and semen-quality parameters were evaluated according to the World Health Organization guidelines. GSTT1 genotype significantly modified the association between exposure to Br-THMs (sum of BDCM, DBCM and TBM) and below-reference sperm motility (Pint=0.02). Men with above-median blood Br-THM levels had an increased odds ratio (OR) of below-reference sperm compared to men with below-median blood Br-THM levels (OR=2.15, 95% CI: 1.11, 4.19) in the GSTT1 null genotype only. In addition, we found that men with a TT of CYP2E1 rs 915,906 had higher blood TCM and TTHM (sum of TCM, BDCM, DBCM and TBM) concentrations than men with a CT/CC of CYP2E1 rs 915,906. Our results suggest that GSTT1 polymorphisms modify Br-THM exposure relation with semen quality, and CYP2E1 polymorphisms are associated with internal levels of exposure to THMs.

Association of polymorphisms in glutathione S-transferase genes (GSTM1, GSTT1, GSTP1) with idiopathic azoospermia or oligospermia in Sichuan, China

The reported effects of the glutathione S-transferase (GSTs) genes (GSTM1, GSTT1, and GSTP1) on male factor infertility have been inconsistent and even contradictory. Here, we conducted a case-control study to investigate the association between functionally important polymorphisms in GST genes and idiopathic male infertility. The study group consisted of 361 men with idiopathic azoospermia, 118 men with idiopathic oligospermia, and 234 age-matched healthy fertile male controls. Genomic DNA was extracted from the peripheral blood, and analyzed by polymerase chain reaction and restriction fragment length polymorphism analysis. There was a significant association between the GSTP1 variant genotype (Ile/Val + Val/Val) with idiopathic infertility risk (odds ratio [OR]: 1.53; 95% confidence interval [CI]: 1.11–2.11; P = 0.009). Similarly, a higher risk of infertility was noted in individuals carrying a genotype combination of GSTT1-null and GSTP1 (Ile/Val + Val/Val) (OR: 2.17; 95% CI: 1.43–3.31; P = 0.0002). These results suggest an increased risk of the GSTP1 variant genotype (Ile/Val + Val/Val) for developing male factor infertility. Our findings also underrate the significance of the effect of GSTM1 and/or GSTT1 (especially the former) in modulating the risk of male infertility in males from Sichuan, southwest China.

Variations in Antioxidant Genes and Male Infertility

Oxidative stress and reactive oxygen species (ROS) are generated from both endogenous and environmental resources, which in turn may cause defective spermatogenesis and male infertility. Antioxidant genes, which include catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST), nitric oxide synthase (NOS), nuclear factor erythroid 2-related factor 2 (NRF2), and superoxide dismutase (SOD), play important roles in spermatogenesis and normal sperm function. In this review, we discuss the association between variations in major antioxidant genes and male infertility. Numerous studies have suggested that genetic disruption or functional polymorphisms in these antioxidant genes are associated with a higher risk for male infertility, which include low sperm quality, oligoasthenoteratozoospermia, oligozoospermia, and subfertility. The synergistic effects of environmental ROS and functional polymorphisms on antioxidant genes that result in male infertility have also been reported. Therefore, variants in antioxidant genes, which independently or synergistically occur with environmental ROS, affect spermatogenesis and contribute to the occurrence of male infertility. Large cohort and multiple center-based population studies to identify new antioxidant genetic variants that increase susceptibility to male infertility as well as validate its potential as genetic markers for diagnosis and risk assessment for male infertility for precise clinical approaches are warranted.

Genetic polymorphisms of glutathione S-transferase M1 and T1, and evaluation of oxidative stress in patients with non-small cell lung cancer

BACKGROUND

Our objective is to investigate the genetic polymorphisms of the glutathione S-transferase M1 and T1 genes (GSTM1 and GSTT1) and evaluate oxidative damage in patients with non-small lung cancer (N-SCLC).

METHODS

One hundred and ten patients with N-SCLC and 100 controls are included in this case-control study. Multiplex polymerase chain reaction (PCR) analyses were used to identify the genotypes. The activities of malondialdehyde (MDA) and nitric oxide (NO) and total antioxidant capacity (T-AOC) were detected by spectroscopic analysis.

RESULTS

The frequencies of the GSTM1, T1, and GSTM1/T1 null genotypes in the patient group were significantly higher than that in the control group (OR = 2.071, P = 0.009; OR = 1.900, P = 0.024; OR = 3.258, P = 0.003). The activities of MDA and NO were significantly higher in the patient group than that in the control group (P <0.001), and T-AOC was significantly lower in patient group than that in control group (P <0.001). The activities of MDA, and NO were higher but the T-AOC was lower in patients with the GSTM1, T1 and M1/T1 null genotypes than those in patients with GSTM1, T1 and M1/T1 present genotypes (P <0.001).

CONCLUSIONS

Our results suggest that oxidative damage may be play a important role in patients with N-SCLC, and that GSTM1 and GSTT1 null genotypes may predispose the cells of patients with N-SCLC to increased oxidative damage.

Effects of GSTM1/GSTT1 gene polymorphism and fruit & vegetable consumption on antioxidant biomarkers and cognitive function in the elderly: a community based cross-sectional study

Background

It was reported that Glutathione S-transferase (GST) gene polymorphism and fruit and vegetable (FV) intake were associated with body antioxidant capacity. The oxidative/anti-oxidative imbalance played an important role in the pathogenesis of AD. However, the association of GST genotype, dietary FV consumption with body antioxidant biomarkers and cognitive function in the elderly is not clear.

Objective

The aim of the present study was to determine the association of GST genotype, and dietary FV intake, with antioxidant biomarkers and cognitive function in the elderly.

Methods

Food frequency questionnaire was used to collect data of dietary FV intakes in 504 community dwelling elderly aged from 55 to 75 years old. GSTM1 and GSTT1 genotypes were determined by using multiple-PCR method. Plasma and erythrocyte antioxidant biomarkers were measured. Cognitive function was measured by using Montreal Cognitive Assessment. Statistical analysis was applied for exploring the association of GST genotype and FV intake with antioxidant biomarkers level and cognitive function in the elderly.

Results

Individual GSTM1 or GSTT1 gene deletion affects body antioxidant biomarkers levels, including erythrocyte GST activity, plasma total antioxidant capacity, and glutathione levels. GSTM1and/or GSTT1 gene deletion have no effects on cognitive function in the surveyed participants. The effect of GST genotype on antioxidant biomarkers are FV intake dependent. There is interaction of FV intake and GST genotype on cognitive function in the elderly.

Conclusion

GST genotype or daily FV consumption impact body antioxidant biomarkers, but not cognitive function in the elderly. There were combined effects of GST genotype and FV consumption on cognitive function in the elderly population. Large scale perspective population study is required to explore the association of GST genetic polymorphism, FV consumption and antioxidant biomarkers and cognitive function in the elderly.

GSTM1 and GSTT1 null polymorphisms and male infertility risk: an updated meta-analysis encompassing 6934 subjects

Published data on the association between the GST genes polymorphisms and male infertility risk are inconclusive. We investigated GST genes polymorphisms in a large sample size case-control study, and conducted a literature-based meta-analysis of 6934 individuals. Our case-control study showed the GSTM1 null genotype was significantly associated with idiopathic oligozoospermia, while the null genotype of GSTT1 was significantly associated with normozoospermia and azoospermia. Additionally, significantly elevated GSTT1 expression levels were observed in present genotype compared with null genotype. In the meta-analysis, the null genotype of GSTM1 was associated with a significantly increased risk of male infertility. Furthermore, a stratification analysis showed that the risk of GSTM1 polymorphism was associated with male infertility in both Asian and Caucasian groups. Further studies of GSTM1 and GSTT1 with their biological functions are needed to understand the role of these genes in the development of male infertility.

Association between 3801T>C polymorphism of CYP1A1 and idiopathic male infertility risk: a systematic review and meta-analysis

BACKGROUND

Epidemiological studies have evaluated the association between 3801T>C polymorphism of CYP1A1 gene and the risk for idiopathic male infertility, but the results are inconclusive. We aimed to derive a more precise estimation of the relationship by conducting a meta-analysis of case-control studies.

METHODS

This study conformed to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Embase and CNKI databases were searched through November 2013 to identify relevant studies. Pooled odds ratios with 95% confidence intervals were used to assess the strength of the association between CYP1A1 3801T>C polymorphism and idiopathic male infertility risk. Q-test was performed to evaluate between-study heterogeneity and publication bias was appraised using funnel plots. Sensitivity analyses were conducted to evaluate the robustness of meta-analysis findings.

RESULTS

Six studies involving 1,060 cases and 1,225 controls were included in this meta-analysis. Overall, significant associations between 3801T>C polymorphism and idiopathic male infertility risk were observed in allelic comparison (OR = 1.36, 95% CI: 1.01-1.83), homozygous model (OR = 2.18, 95% CI: 1.15-4.12), and recessive model (OR = 1.86, 95% CI: 1.09-3.20), with robust findings according to sensitivity analyses. However, subgroup analyses did not further identify the susceptibility to idiopathic male infertility in all comparisons. Funnel plot inspections did not reveal evidence of publication bias.

CONCLUSIONS

The current meta-analysis provides evidence of a significant association between CYP1A1 3801T>C polymorphism and idiopathic male infertility risk. Considering the limitation inherited from the eligible studies, further confirmation in large-scale and well-designed studies is needed.

Association of GSTM1 and GSTT1 genes with the susceptibility to male infertility: result from a meta-analysis

The deletion polymorphisms of the glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) genes were considered as candidates for genetic susceptibility factors of male infertility. Previous studies concerning the relationship between the null genotype of the two genes and male infertility have been reported in recent years. However, the results remain elusive. A meta-analysis was performed to estimate the relationship between the deletion polymorphism of the GSTM1 or GSTT1 gene, and male infertility in this study. Sixteen studies concerning the GSTM1 gene, including 2174 cases and 1861 controls, and 13 case-control studies on the GSTT1 gene with a total number of 1992 cases and 1617 controls were processed. The results showed that the null genotype of the GSTM1 gene was associated with male infertility in the overall populations (P=0.003, OR=1.40, 95%CI=1.12-1.75), especially in Caucasian (P=0.012, OR=1.50, 95%CI=1.09-2.07) as well as Chinese (P=0.001, OR=1.55, 95%CI=1.19-2.03). The null genotype of the GSTT1 gene was strongly related to male infertility only in Chinese (P=0.000, OR=1.70, 95%CI=1.34-2.14). These results indicated that the null genotype of the GSTM1 gene might contribute to the susceptibility of male infertility, whereas the null genotype of the GSTT1 gene may be a genetic susceptibility factor of male infertility for the Chinese.

Association of the Glutathione S-transferases M1 and T1 polymorphism with male infertility: a meta-analysis

BACKGROUND

Genes of different pathways regulate spermatogenesis, and the complexity of the spermatogenic process indicates that polymorphisms or mutations in these genes could cause male infertility. Published data on the association between the GSTM1 and GSTT1 polymorphism and male infertility risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed.

METHODS

A total of 11 studies regarding GSTM1 and 9 studies regarding GSTT1 between 1999 and 2012 were identified through researching MEDLINE, EMBASE and the Chinese Biomedical Database. It was performed to obtain summary estimated odd ratios and 95 % confidence intervals of GSTM1 and GSTT1 for male infertility, with attention to study quality and publication bias.

RESULTS

Overall, a significant association was seen between GSTM1 (OR=1.20, 95 % CI=1.02-1.40, P(heterogeneity) =0.000, P=0.027) genotypes and male infertility. Significant associations were also observed in subgroups of Caucasian populations (OR=1.65, 95 %CI=1.16-2.34, P(heterogeneity) =0.006, P=0.005), but were not observed in Asian populations (OR=1.09, 95 % CI=0.72-1.65, P(heterogeneity) =0.054, P=0.697) when stratified by ethnicity. While there was no significant association was seen between GSTT1 (OR=1.00, 95 % CI=0.74-1.35, P(heterogeneity) =0.000, P=0.980) null genotypes and male infertility. Simultaneously, significant associations were not observed in subgroups of Caucasian populations (OR=0.94, 95 %CI=0.44-2.00, P(heterogeneity) =0.000, P=0.867) and Asian populations (OR=0.93, 95 % CI=0.46-1.87, P(heterogeneity) =0.002, P=0.838) when stratified by ethnicity.

CONCLUSION

Our results suggest the GSTM1 null genotype contributes to male infertility susceptibility, while GSTT1 gene polymorphisms are not associated with male infertility in our study.