Oxidative stress pathway genes and chronic renal insufficiency in Asian Indians with Type 2 diabetes

Association between nitric oxide synthase (NOS3) gene polymorphisms and diabetic nephropathy: An updated meta-analysis

Polymorphisms located within NOS3 gene have been investigated as susceptibility variants for diabetic nephropathy (DN) in type 2 diabetes mellitus (T2DM) in a large number of studies. However, these previous articles yielded inconsistent results and we aimed at elucidating the impact of NOS3 variants on DN risk in T2DM by conducting an updated systematic data synthesis. A total of 36 studies (12,807 participants) were selected for qualitative data synthesis, while 33 records with 11,649 subjects were included in the meta-analysis. The pooled analysis demonstrated the association of minor alleles of rs2070744 and rs1799983 with an increased susceptibility to DN (P < 0.001 and P = 0.015 for allelic model, respectively). For both of these variants, a significant effect of subgrouping according to ethnicity was found. Rs869109213 displayed an association with DN susceptibility, with pooled effect measures indicating a predisposing effect of the minor allele a (Prec = 0.002, ORrec = 1.960, 95%CI 1.288-2.983; Paavs. bb = 0.001, ORaavs. bb = 2.014, 95%CI 1.316-3.083). These findings support the effects of NOS3 variants on the risk of developing DN in T2DM.

Risk association of the nitric oxide synthase VNTR intron 4 a/b variant with diabetic nephropathy - a pilot study

Diabetic nephropathy (DN) is known to be a leading complication of type 2 diabetes mellitus (T2D). This study evaluated whether the VNTR intron 4 a/b and rs1799983 polymorphisms of endothelial-derived nitric oxide synthase (eNOS) gene modulated the risk of developing DN in Asian Indian patients. The eNOS variants were genotyped in 200 patients, 100 with DN and 100 without DN. A significant risk association was observed for the VNTR intron 4 a/b (p < 0.05). Haplotype analysis revealed that the allele combination of rs1799983894 G/Intron 4b and rs1799983894 T/Intron 4b had a statistically significant inverse association with DN.

A case-control study and systematic review of the association between glutathione S-transferase genes and chronic kidney disease

Background

GSTM1 deletion was reported to be associated with CKD progression in cohort studies. However, the results of case‒control studies were conflicting. The association between GST genes and CKD progression needs to be studied in China. Therefore, we conducted this case‒control study and systematic review for Southwest China to outline the association between GST genes and CKD.

Methods

CKD patients and healthy controls were enrolled from June 1, 2022 to 1 August 2022. Reported case‒control studies were identified by searching databases until 1 September 2022 for meta-analysis.

Results

Significant associations were found between deletions of GSTM1 and GSTT1 and CKD risk (all P < 0.01) but not in GSTP1 rs1695 (all P > 0.05) in Southwest China. Then, we conducted a meta-analysis on 30 studies and found positive associations between deletions of GSTM1 and GSTT1 and CKD risk (all P < 0.01) but failed to find associations in GSTP1 rs1695 (all P > 0.05). Stratification analysis for ethnicity only showed a significant association in Southern Asia (P < 0.05) but not in Eastern Asia or other populations. This was different from our case‒control results. The current evidence was influenced by study quality and PCR method but not by control selection. Given the different stages of CKD patients, a subanalysis of disease stages was performed, and the results remained positive. Interestingly, we found no significant associations between DM-CKD and GST genes, which should be interpreted with caution.

Conclusion

We found that GSTM1 and GSTT1 null genotypes were risk factors for CKD in China. The results of the meta-analysis were somewhat different from our results. We considered that antioxidant therapy might be useful for the treatment of these patients.

Association between the Polymorphisms rs2070744, 4b/a and rs1799983 of the NOS3 Gene with Chronic Kidney Disease of Uncertain or Non-Traditional Etiology in Mexican Patients

Background and Objectives: Chronic Kidney Disease of uncertain or non-traditional etiology (CKDnT) is a form of chronic kidney disease of undetermined etiology (CKDu) and is not associated with traditional risk factors. The aim of this study was to investigate the association of polymorphisms rs2070744, 4b/a and rs1799983 of the NOS3 gene with CKDnT in Mexican patients. Materials and Methods: We included 105 patients with CKDnT and 90 controls. Genotyping was performed by PCR-RFLP's, genotypic and allelic frequencies were determined and compared between the two groups using χ2 analysis, and differences were expressed as odd ratios with 95% confidence intervals (CI). Values of p < 0.05 were considered statistically significant. Results: Overall, 80% of patients were male. The rs1799983 polymorphism in NOS3 was found to be associated with CKDnT in the Mexican population (p = 0.006) (OR = 0.397; 95% CI, 0.192-0.817) under a dominant model. The genotype frequency was significantly different between the CKDnT and control groups (χ2 = 8.298, p = 0.016). Conclusions: The results of this study indicate that there is an association between the rs2070744 polymorphism and CKDnT in the Mexican population. This polymorphism can play an important role in the pathophysiology of CKDnT whenever there is previous endothelial dysfunction.

Individual and combined effects of the GSTM1, GSTT1, and GSTP1 polymorphisms on type 2 diabetes mellitus risk: A systematic review and meta-analysis

Backgrounds: Compared with previously published meta-analyses, this is the first study to investigate the combined effects of glutathione-S-transferase polymorphisms (GSTM1, GSTT1 and GSTP1 IIe105Val) and type 2 diabetes mellitus (T2DM) risk; moreover, the credibility of statistically significant associations was assessed; furthermore, many new original studies were published. Objectives: To determine the relationship between GSTM1, GSTT1, and GSTP1 polymorphisms with T2DM risk. Methods: PubMed, Embase, Wanfang, and China National Knowledge Infrastructure Databases were searched. We quantify the relationship using crude odds ratios and their 95% confidence intervals Moreover, the Venice criteria, false-positive report probability (FPRP), and Bayesian false discovery probability (BFDP) were used to validate the significance of the results. Results: Overall, significantly increased T2DM risk was found between individual and combined effects of GSTM1, GSTT1, and GSTP1 polymorphisms on T2DM risk, but, combined effects of the GSTT1 and GSTP1 polymorphisms was not statistically significant. GSTT1 gene polymorphism significantly increases the risk of T2DM complications, while GSTM1 and GSTP1 polymorphisms had no statistical significance. The GSTM1 null genotype was linked to a particularly increased risk of T2DM in Caucasians; the GSTT1 null genotype was connected to a significantly higher risk of T2DM in Asians and Indians; and the GSTP1 IIe105Val polymorphism was related to a substantially increased T2DM risk in Indians. Moreover, the GSTM1 and GSTT1 double null genotype was associated with substantially increased T2DM risk in Caucasians and Indians; the combined effects of GSTM1 and GSTP1 polymorphisms was associated with higher T2DM risk in Caucasians. However, all significant results were false when the Venice criteria, FPRP, and BFDP test were used (any FPRP >0.2 and BFDP value >0.8). Conclusion: The current analysis strongly suggests that the individual and combined effects of GSTM1, GSTT1 and GSTP1 polymorphisms might not be connected with elevated T2DM risk.

Epithelial nitric oxide synthases (eNOS) 894 G < T polymorphism and diabetic nephropathy susceptibility: A meta-analysis

Objective

To investigate the epithelial nitric oxide synthases (eNOS) 894 G < T polymorphism and diabetic nephropathy (DN) susceptibility by pooling the open published data.

Methods

Studies relevant to eNOS 894 G < T polymorphism and DN susceptibility published in PubMed, EMBASE, Medline, CNKI, and Wanfang databases were systematically screened by using the text words of endothelial nitric oxide synthase, eNOS, NOS-3, G894T, rs179983, polymorphism, diabetic nephropathy, and DN. The correlation between eNOS 894 G < T polymorphism and DN susceptibility was demonstrated by odds ratio (OR) and corresponding 95% confidence interval (95% CI). The data were combined through fixed or random effect model according to statistical heterogeneity. The publication bias was assessed by Begg’s funnel plot and Egger’s line regression test.

Results

Twenty-six case-control studies relevant to eNOS 894 G < T polymorphism and DN susceptibility were identified by electronic searching of the related databases. Type 2 diabetes mellitus (T2MD) patients with T allele had increased susceptibility to DN compared with G allele under homologous gene model (TT vs GG) (OR = 1.40, 95% CI: 1.16–1.69, p = 0.001), dominant gene model (TT + GT) vs GG (OR = 1.61, 95% CI: 1.30–2.00, p = 0.000) and recessive gene model TT vs (GT + GG) (OR = 1.39, 95% CI: 1.16–1.66, p = 0.000). Publication bias was not statistically significant for homologous and recessive gene model.

Conclusion

Based on the present evidence, DN risk was increased in T2MD cases with T allele compared to G allele.

Prevalence of uncoupling protein one genetic polymorphisms and their relationship with cardiovascular and metabolic health

Contribution of UCP1 single nucleotide polymorphisms (SNPs) to susceptibility for cardiometabolic pathologies (CMP) and their involvement in specific risk factors for these conditions varies across populations. We tested whether UCP1 SNPs A-3826G, A-1766G, Ala64Thr and A-112C are associated with common CMP and their risk factors across Armenia, Greece, Poland, Russia and United Kingdom. This case-control study included genotyping of these SNPs, from 2,283 Caucasians. Results were extended via systematic review and meta-analysis. In Armenia, GA genotype and A allele of Ala64Thr displayed ~2-fold higher risk for CMP compared to GG genotype and G allele, respectively (p<0.05). In Greece, A allele of Ala64Thr decreased risk of CMP by 39%. Healthy individuals with A-3826G GG genotype and carriers of mutant allele of A-112C and Ala64Thr had higher body mass index compared to those carrying other alleles. In healthy Polish, higher waist-to-hip ratio (WHR) was observed in heterozygotes A-3826G compared to AA homozygotes. Heterozygosity of A-112C and Ala64Thr SNPs was related to lower WHR in CMP individuals compared to wild type homozygotes (p<0.05). Meta-analysis showed no statistically significant odds-ratios across our SNPs (p>0.05). Concluding, the studied SNPs could be associated with the most common CMP and their risk factors in some populations.

Meta-Analysis and Bioinformatics Detection of Susceptibility Genes in Diabetic Nephropathy

The latest meta-analysis of genome-wide linkage studies (GWLS) identified nine cytogenetic locations suggestive of a linkage with diabetic nephropathy (DN) due to type 1 diabetes mellitus (T1DM) and seven locations due to type 2 diabetes mellitus (T2DM). In order to gain biological insight about the functional role of the genes located in these regions and to prioritize the most significant genetic loci for further research, we conducted a gene ontology analysis with an over representation test for the functional annotation of the protein coding genes. Protein analysis through evolutionary relationships (PANTHER) version 16.0 software and Cytoscape with the relevant plugins were used for the gene ontology analysis, and the overrepresentation test and STRING database were used for the construction of the protein network. The findings of the over-representation test highlight the contribution of immune related molecules like immunoglobulins, cytokines, and chemokines with regard to the most overrepresented protein classes, whereas the most enriched signaling pathways include the VEGF signaling pathway, the Cadherin pathway, the Wnt pathway, the angiogenesis pathway, the p38 MAPK pathway, and the EGF receptor signaling pathway. The common section of T1DM and T2DM results include the significant over representation of immune related molecules, and the Cadherin and Wnt signaling pathways that could constitute potential therapeutic targets for the treatment of DN, irrespective of the type of diabetes.

Association between nitric oxide synthase T-786C genetic polymorphism and chronic kidney disease: Meta-analysis incorporating trial sequential analysis

BACKGROUND

Several meta-analyses of the relationship between endothelial nitric oxide synthase (eNOS) T-786C gene polymorphism and chronic kidney disease (CKD) have been published. However, the results of these studies were inconsistent, and it is undetermined whether sample sizes are sufficient to reach a definite conclusion.

OBJECTIVE

To elucidate the relationship between T-786C and CKD by combining previous studies with our case-control sample and incorporate trial sequential analysis (TSA) to verify whether the sample size is adequate to draw a definite conclusion.

METHODS

PubMed and Embase databases were searched for relevant articles on eNOS T-786C and CKD before February 28, 2021. TSA was also incorporated to ascertain a conclusion. A total of 558 hemodialysis cases in the case-control study was recruited from nine dialysis centers in the northern area of Taiwan in 2020. Additionally, 640 healthy subjects of the control group, with estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m2, were selected from participants of the annual elderly health examination program at the Tri-Service General Hospital. The functional analysis was based on eQTL data from GTExPortal.

RESULTS

After screening with eligibility criteria, 15 papers were included and eventually combined in a meta-analysis. The result of the TSA showed that the sample size for Caucasians was adequate to ascertain the correlation between eNOS T-786C and CKD but was insufficient for Asians. Therefore, we added our case-control samples (n = 1198), though not associated with CKD (odds ratio [OR] = 1.01, 95% confidence interval [CI] = 0.69-1.46), into a meta-analysis, which supported that eNOS T-786C was significantly associated with CKD in Asians (OR = 1.39, 95% CI = 1.04-1.85) by using an adequate cumulative sample size (n = 4572) analyzed by TSA. Data of eQTL from GTEx showed that T-786C with the C minor allele exhibited relatively lower eNOS mRNA expression in whole blood, indicating the hazardous role of eNOS T-786C in CKD.

CONCLUSIONS

eNOS T-786C genetic polymorphism was of conclusive significance in the association with CKD among Asians in our meta-analysis. Our case-control samples play a decisive role in changing conclusions from indefinite to definite.

Association of eNOS and MCP-1 Genetic Variants with Type 2 Diabetes and Diabetic Nephropathy Susceptibility: A Case-Control and Meta-Analysis Study

Type 2 diabetes (T2D) and its secondary complications result from the complex interplay of genetic and environmental factors. To understand the role of these factors on disease susceptibility, the present study was conducted to assess the association of eNOS and MCP-1 variants with T2D and diabetic nephropathy (DN) in two ethnically and geographically different cohorts from North India. A total of 1313 subjects from two cohorts were genotyped for eNOS (rs2070744, rs869109213 and rs1799983) and MCP-1 (rs1024611 and rs3917887) variants. Cohort-I (Punjab) comprised 461 T2D cases (204 T2D with DN and 257 T2D without DN) and 315 healthy controls. Cohort-II (Jammu and Kashmir) included 337 T2D (150 T2D with DN and 187 T2D without DN) and 200 controls. Allele, genotype and haplotype frequencies were compared among the studied participants, and phenotype-genotype interactions were determined. Meta-analysis was performed to investigate the association between the selected variants and disease susceptibility. All three eNOS variants were associated with 1.5-4.0-fold risk of DN in both cohorts. MCP-1 rs1024611 conferred twofold risk towards DN progression in cohort-II, while rs3917887 provided twofold risk for both T2D and DN in both cohorts. eNOS and MCP-1 haplotypes conferred risk for T2D and DN susceptibility. Phenotype-genotype interactions showed significant associations between the studied variants and anthropometric and biochemical parameters. In meta-analysis, all eNOS variants conferred risk towards DN progression, whereas no significant association was observed for MCP-1 rs1024611. We show evidences for an association of eNOS and MCP-1 variants with T2D and DN susceptibility.

Association study between superoxide Dismutases gene polymorphisms and development of diabetic retinopathy and cataract in Iranian patients with type two diabetes mellitus

PURPOSE

Reactive oxygen species (ROS) plays pathological roles on development of diabetic retinopathy (DR) and cataract. Superoxide dismutases (SODs) are a set of enzymes to eliminate ROS and cell protection. Based on the diminished activities of SOD1 during DR and cataract, the polymorphisms within SOD1 gene may be associated with these disorders. This study assessed the relationship between SOD1 -251A/G (rs2070424) and SOD1 + 35A/C (rs2234694) gene polymorphisms and DR and cataract in Iranian patients with type 2 diabetes mellitus (T2DM).

METHODS

Totally, 141 cases (73 patients with cataract and 68 with DR) with a at least five years history of T2DM and 119 age/gender matched persons without history of DM were included in the case and control groups, respectively. Genomic DNA was extracted from peripheral venous blood cells and genotyping of 251A/G and + 35A/C polymorphisms was done using PCR-RFLP technique. Statistical analysis was done using SPSS version 22.

RESULTS

Results showed SOD1 -251A/G and + 35A/C genotype frequency were significantly associated (1.9 folds) with cataract (P = 0.045, OR = 0.524, 95% CI = 0.277-0.991 and P = 0.037, OR = 0.505, 95% CI = 0.265-.0965, respectively). Instead, no significant differences found between SOD -251A/G (P = 0.053, OR = 0.52, 95% CI = 0.276-1.014) and + 35A/C (P = 0.073, OR = 0.547, 95% CI = 0.281-1.063) polymorphisms and DR. Multivariate Logistic Regression model showed significant relationship between BMI, HDL and TC levels and independent predictors of T2DM (P < 0.05).

CONCLUSIONS

Based on the results, there was significant association between SOD1 gene polymorphisms and cataract in patients with T2DM. Therefore, SOD1 gene polymorphisms might be a potential marker for increased risk of cataract in patients with T2DM.

Concentration/activity of superoxide dismutase isozymes and the pro-/antioxidative status, in context of type 2 diabetes and selected single nucleotide polymorphisms (genes: INS, SOD1, SOD2, SOD3) - Preliminary findings

The alterations in concentration/activity of superoxide dismutase isozymes in the context of type 2 diabetes or obesity are well-described. Moreover, many hereditary factors, including single-nucleotide polymorphisms (SNPs) of genes for coding insulin, insulin receptors, or insulin receptor substrates (INS, INSR, IRS1, IRS2) or superoxide dismutase isozymes (SOD1, SOD2, SOD3), have been linked with the incidence of obesity and diabetes. However, the underlying changes in the plasma concentration/activity of superoxide dismutase isozymes and their potential connection with the said hereditary factors remain unexplored. Previously, we have observed that the plasma concentration/activity of superoxide dismutase isozymes differs in the context of obesity and/or rs2234694 (SOD1) and rs4880 (SOD2) and that the concentrations of SOD1, SOD2, SOD3 are correlated with each other. Intersexual variability of SOD1 concentration was detected regardless of obesity. In this study, the variability of concentration/activity of superoxide dismutase isozymes in plasma is considered in the context of type 2 diabetes and/or SNPs: rs2234694 (SOD1), rs5746105 (SOD2), rs4880 (SOD2), rs927450 (SOD2), rs8192287 (SOD3). Genotypic variability of SNP rs3842729 (INS), previously studied in the context of insulin-dependent diabetes, is investigated in terms of selected clinical parameters associated with type 2 diabetes. This study revealed higher SOD1 concentration in diabetic men compared to women, and extremely high SOD1 concentration, higher total superoxide dismutase, and copper-zinc superoxide dismutase activity, and lower superoxide dismutase and copper-zinc superoxide dismutase activity (when adjusted for the concentration of SODs) in the diabetic group regardless of sex. Multiple logistic regression, applied to explore possible links between the studied SNPs and other factors with the odds of type 2 diabetes or obesity, revealed that the genotypic variability of rs4880 (SOD2) could affect these odds, supporting the findings of several other studies.

-866G/A and Ins/Del polymorphisms in the UCP2 gene and diabetic kidney disease: case-control study and meta-analysis

Uncoupling protein 2 (UCP2) decreases reactive oxygen species (ROS). ROS overproduction is a key contributor to the pathogenesis of diabetic kidney disease (DKD). Thus, UCP2 polymorphisms are candidate risk factors for DKD; however, their associations with this complication are still inconclusive. Here, we describe a case-control study and a meta-analysis conducted to investigate the association between UCP2 -866G/A and Ins/Del polymorphisms and DKD. The case-control study comprised 385 patients with type 1 diabetes mellitus (T1DM): 223 patients without DKD and 162 with DKD. UCP2 -866G/A (rs659366) and Ins/Del polymorphisms were genotyped by real-time PCR and conventional PCR, respectively. For the meta-analysis, a literature search was conducted to identify all studies that investigated associations between UCP2 polymorphisms and DKD in patients with T1DM or type 2 diabetes mellitus. Pooled odds ratios were calculated for different inheritance models. Allele and genotype frequencies of -866G/A and Ins/Del polymorphisms did not differ between T1DM case and control groups. Haplotype frequencies were also similar between groups. Four studies plus the present one were eligible for inclusion in the meta-analysis. In agreement with case-control data, the meta-analysis results showed that the -866G/A and Ins/Del polymorphisms were not associated with DKD. In conclusion, our case-control and meta-analysis studies did not indicate an association between the analyzed UCP2 polymorphisms and DKD.

GSTM1 Copy Number Is Not Associated With Risk of Kidney Failure in a Large Cohort

Deletion of glutathione S-transferase µ1 (GSTM1) is common in populations and has been asserted to associate with chronic kidney disease progression in some research studies. The association needs to be validated. We estimated GSTM1 copy number using whole exome sequencing data in the DiscovEHR cohort. Kidney failure was defined as requiring dialysis or receiving kidney transplant using data from the electronic health record and linkage to the United States Renal Data System, or the most recent eGFR < 15 ml/min/1.73 m². In a cohort of 46,983 unrelated participants, 28.8% of blacks and 52.1% of whites had 0 copies of GSTM1. Over a mean of 9.2 years follow-up, 645 kidney failure events were observed in 46,187 white participants, and 28 in 796 black participants. No significant association was observed between GSTM1 copy number and kidney failure in Cox regression adjusting for age, sex, BMI, smoking status, genetic principal components, or comorbid conditions (hypertension, diabetes, heart failure, coronary artery disease, and stroke), whether using a genotypic, dominant, or recessive model. In sensitivity analyses, GSTM1 copy number was not associated with kidney failure in participants that were 45 years or older at baseline, had baseline eGFR < 60 ml/min/1.73 m², or with baseline year between 1996 and 2002. In conclusion, we found no association between GSTM1 copy number and kidney failure in a large cohort study.

MiR-30e-5p and MiR-15a-5p Expressions in Plasma and Urine of Type 1 Diabetic Patients With Diabetic Kidney Disease

Introduction

Diabetic kidney disease (DKD) is a common microvascular complication that affects 40% of patients with diabetes mellitus (DM). Emerging evidence suggests a role for several microRNAs (miRNAs) in the development of DKD. In this context, miR-15a-5p and miR-30e-5p have been shown to regulate the expression of the uncoupling protein 2 (UCP2), a mitochondrial protein that decreases reactive oxygen species (ROS) formation by the mitochondria. Since ROS overproduction is a key contributor to the pathogenesis of DKD, dysregulation of these two miRNAs could be involved in DKD pathogenesis. Thus, the aim of this study was to compare the expressions of miR-15a-5p and miR-30e-5p in type 1 DM (T1DM) patients with DKD (cases) and without this complication (controls), and to perform bioinformatics analyses to investigate their putative targets and biological pathways under their regulation.

Methods

MiR-15a-5p and miR-30e-5p expressions were analyzed in plasma and urine of 17 T1DM controls and 23 DKD cases (12 with moderate DKD and 11 with severe DKD) using qPCR. Bioinformatics analyses were performed in Cytoscape software.

Results

MiR-30e-5p expression was downregulated in plasma of patients with moderate and severe DKD compared to T1DM controls. Moreover, this miRNA was also downregulated in urine of patients with severe DKD compared to the other groups. No difference was found in miR-15a-5p expression between groups. Bioinformatics analyses indicated that miR-30e-5p and miR-15a-5p regulate various genes that participate in pathways related to angiogenesis, apoptosis, cell differentiation, oxidative stress, and hypoxia.

Conclusion

MiR-30e-5p seems to be downregulated in plasma and urine of patients with DKD.

CNDP1, NOS3, and MnSOD Polymorphisms as Risk Factors for Diabetic Nephropathy among Type 2 Diabetic Patients in Malaysia

Type 2 diabetes mellitus (T2DM) is associated with a high incidence of nephropathy. The aim of this study was to investigate the association of a genetic polymorphism of carnosinase (CNDP1-D18S880 and -rs2346061), endothelial nitric oxide synthase (NOS3-rs1799983), and manganese superoxide dismutase (MnSOD-rs4880) genes with the development of diabetic nephropathy among Malaysian type 2 diabetic patients. A case-control association study was performed using 652 T2DM patients comprising 227 Malays (without nephropathy = 96 and nephropathy = 131), 203 Chinese (without nephropathy = 95 and nephropathy = 108), and 222 Indians (without nephropathy = 136 and nephropathy = 86). DNA sequencing was performed for the D18S880 of CNDP1, while the rest were tested using DNA Sequenom MassARRAY to identify the polymorphisms. DNA was extracted from the secondary blood samples taken from the T2DM patients. The alleles and genotypes were tested using four genetic models, and the best mode of inheritance was chosen based on the least p value. The rs2346061 of CNDP1 was significantly associated with diabetic nephropathy among the Indians only with OR = 1.94 and 95% CI = (1.76–3.20) and fitted best the multiplicative model, while D18S880 was associated among all the three major races with the Malays having the strongest association with OR = 2.46 and 95% CI = (1.48–4.10), Chinese with OR = 2.26 and 95% CI = (1.34–3.83), and Indians with OR = 1.77 and 95% CI = (1.18–2.65) in the genotypic multiplicative model. The best mode of inheritance for both MnSOD and NOS3 was the additive model. For MnSOD-rs4880, the Chinese had OR = 2.8 and 95% CI = (0.53–14.94), Indians had OR = 2.4 and 95% CI = (0.69–2.84), and Malays had OR = 2.16 and 95% CI = (0.54–8.65), while for NOS3-rs1799983, the Indians had the highest risk with OR = 3.16 and 95% CI = (0.52–17.56), followed by the Chinese with OR = 3.55 and 95% CI = (0.36–35.03) and the Malays with OR = 2.89 and 95% CI = (0.29–28.32). The four oxidative stress-related polymorphisms have significant effects on the development of nephropathy in type 2 diabetes patients. The genes may, therefore, be considered as risk factors for Malaysian subjects who are predisposed to T2DM nephropathy.

The Associations between Paraoxonase 1 L55M/Q192R Genetic Polymorphisms and the Susceptibilities of Diabetic Macroangiopathy and Diabetic Microangiopathy: A Meta-Analysis

INTRODUCTION

Plenty of studies have focused on the associations of paraoxonase 1 Q192R and L55M genetic polymorphisms with diabetic macroangiopathy and microangiopathy susceptibility, but these associations remain controversial. Therefore, this meta-analysis was conducted to demonstrate these relationships.

METHODS

Relevant studies published in English or Chinese were identified in PubMed, Embase, Wanfang Database, and CNKI by applying specific inclusion and exclusion criteria. Statistical analyses were performed using the STATA 12.0 statistical software.

RESULTS

25 Case-control studies were included in the meta-analyses: six on the association between paraoxonase 1 L55M genetic polymorphism and diabetic macroangiopathy risk, nine on the association between L55M and diabetic microangiopathy risk, 12 on the association between Q192R and diabetic macroangiopathy risk, and 12 on the association between Q192R and diabetic microangiopathy risk. Paraoxonase 1 L55M genetic polymorphism was significantly associated with diabetic microangiopathy susceptibility in the dominant model [odds ratio (OR) 0.53, 95% confidence interval (CI) 0.33-0.83, P = 0.006], the homozygous model (OR 0.37, 95% CI 0.16-0.86, P = 0.021), the allelic contrast model (OR 0.62, 95% CI 0.43-0.90, P = 0.011), the recessive model (OR 12.04, 95% CI 8.02-18.06, P = 0.000), and the heterozygous model (OR 0.57, 95% CI 0.38-0.85, P = 0.006), but L55M was not significantly associated with macroangiopathy susceptibility. Paraoxonase 1 Q192R genetic polymorphism was significantly associated with diabetic macroangiopathy susceptibility in the homozygous model (OR 1.88, 95% CI 1.06-3.32, P = 0.030), the allelic contrast model (OR 1.31, 95% CI 1.02-1.69, P = 0.038), and the recessive model (OR 1.55, 95% CI 1.11-2.16, P = 0.010), but not in the dominant and heterozygous models. Meanwhile, there was no significant association between paraoxonase 1 Q192R genetic polymorphism and diabetic microangiopathy susceptibility.

CONCLUSION

Paraoxonase 1 L55M and Q192R genetic polymorphisms play important roles in diabetic macroangiopathy and microangiopathy susceptibility. Further well-designed studies based on large samples are needed to confirm these results.

NOS3 Polymorphisms and Chronic Kidney Disease

Chronic kidney disease (CKD) is a multifactorial pathophysiologic irreversible process that often leads to a terminal state in which the patient requires renal replacement therapy. Most cases of CKD are due to chronic-degenerative diseases and endothelial dysfunction is one of the factors that contribute to its pathophysiology. One of the most important mechanisms for proper functioning of the endothelium is the regulation of the synthesis of nitric oxide. This compound is synthesized by the enzyme nitric oxide synthase, which has 3 isoforms. Polymorphisms in the NOS3 gene have been implicated as factors that alter the homeostasis of this mechanism. The Glu298Asp polymorphisms 4 b/a and -786T>C of the NOS3 gene have been associated with a more rapid deterioration of kidney function in patients with CKD. These polymorphisms have been evaluated in patients with CKD of determined and undetermined etiology and related to a more rapid deterioration of kidney function.

Genetic association of NAD(P)H quinone oxidoreductase (NQO1*2) polymorphism with NQO1 levels and risk of diabetic nephropathy

NAD(P)H quinone oxidoreductase 1 (NQO1) catalyzes reactions having a cyto-protective effect against redox cycling and oxidative stress. A single base polymorphism (C/T) at nucleotide 609 of the NQO1 gene impairs the stability and function of its protein. Its role in the development of diabetic nephropathy (DN) has not been deciphered. Therefore, this study aimed to evaluate the association of NQO1*2 (rs1800566) polymorphism with plasma NQO1 levels and DN. This study screened 600 participants including healthy controls (HC), type 2 diabetes mellitus without complications (T2DM) and diabetic nephropathy (DN): 200 each for studying NQO1*2 gene polymorphism using the PCR-RFLP. Plasma NQO1 levels were measured by ELISA. Analysis of variance and logistic regression were used to evaluate the association of NQO1 polymorphism with plasma NQO1 levels and DN. The allelic frequencies of NQO1*1/NQO1*2 were 0.88/0.12 in HC, 0.765/0.235 in T2DM and 0.65/0.35 in DN. Carriers of the NQO1*2 allele had significantly lower plasma NQO1 levels (p<0.05) and revealed higher risk towards the development of DN (OR=1.717, p=0.010). NQO1*2 SNP is a functional polymorphism having a significant effect on NQO1 levels. Our results indicate that NQO1*2 genotype may increase susceptibility to DN in north Indian subjects with T2DM.

Association of CYBA G640A variation with coronary artery disease in Indians

INTRODUCTION

Oxidative stress induces atherosclerosis by triggering an inflammatory cascade within the vascular wall.

OBJECTIVE

To investigate the role of pro-oxidant and antioxidant gene variations with CAD in Indian subjects.

MATERIALS & METHODS

It's a case-control study and genotyping for the variants MPO G-463A, CYBA G640A, SOD2 Val16Ala and CAT C-262T were performed by conventional PCR techniques.

RESULTS

Only CYBA G640A variant allele was found to be significantly (p = 0.0075) associated with CAD.

CONCLUSION

Although CYBA G640A variation was found to be significant, a larger study is needed to validate these results and establish its role as a biomarker.

Polymorphisms in oxidative stress pathway genes and risk of diabetic nephropathy in South Indian type 2 diabetic patients

AIM

Diabetic nephropathy (DN), a common microvascular complication of type 2 diabetes mellitus (T2DM) is polygenic, with a vast array of genes contributing to disease susceptibility. Accordingly, we explored the association between DN and six polymorphisms in oxidative stress related genes, namely eNOS, p22phox subunit of NAD(P)H oxidase, PARP-1 and XRCC1 in South Indian T2DM subjects.

METHODS

The study included 155 T2DM subjects with DN and 162 T2DM patients with no evidence of DN. The selected polymorphisms were genotyped by polymerase chain reaction and Taqman allele discrimination assay.

RESULTS

No significant difference was observed in the genotype and allele distribution of eNOS -786T > C, intron 4a4b, p22phox 242C > T and XRCC1 Arg399Gln polymorphisms between T2DM groups with and without DN. Contrastingly, there appeared to be a significant association of eNOS 894G > T and PARP-1 Val762Ala polymorphisms with DN wherein, the presence of 894T allele was associated with an enhanced risk for DN [P = 0.005; OR = 1.78 (1.17-2.7)], while the 762Ala allele seemed to confer significant protection against DN [P = 0.02; OR = 0.59 (0.37-0.92)]. Multiple logistic regression analysis revealed a significant and independent association of eNOS 894G > T, PARP-1 Val762Ala polymorphisms and hypertension with DN in T2DM individuals.

CONCLUSIONS

eNOS 894G > T and PARP-1 Val762Ala polymorphisms appeared to associate significantly with DN, with the former contributing to an enhanced risk and the latter to a reduced susceptibility to DN in South Indian T2DM individuals.

Oxidative stress-related genes in type 2 diabetes: association analysis and their clinical impact

Worldwide prevalence of diabetes mellitus motivates a number of association studies to be conducted throughout the world. Eleven polymorphisms from nine candidate genes in oxidative stress pathway have been analyzed in eastern Indian type 2 diabetic patients (n = 145) and healthy controls (n = 100). Different biochemical parameters were also analyzed for their association with the disease. Significant associations were observed for rs2070424 A>G SOD1 (OR 3.91, 95% CI 2.265-8.142, P < 0.001), rs854573 A>G PON1 (OR 3.415, 95% CI 2.116-5.512, P < 0.001), rs6954345 G>C PON2 (OR 3.208, 95% CI 2.071-4.969, P < 0.001), RAGE rs1800624 -374 T>A (OR 3.58, 95% CI 2.218-5.766, P < 0.001), and NOS3 -786 T>C (OR 3.75, 95% CI 2.225-6.666, P < 0.001). Haplotype containing two risk alleles of PON1 and PON2 genes was significantly associated with disease (OR 8.34, 95% CI 1.554-44.804, P < 0.002). Our results suggest that carriers of major and efficient alleles of oxidative stress genes are more likely to survive the comorbid complications and single copy of risk allele is sufficient for developing the disease.

Diabetes and associated complications in the South Asian population

The rising prevalence of diabetes in South Asians has significant health and economic implications. South Asians are predisposed to the development of diabetes due to biologic causes which are exacerbated by lifestyle and environmental factors. Furthermore, they experience significant morbidity and mortality from complications of diabetes, most notably coronary artery disease, cerebrovascular disease, and chronic kidney disease. Therefore, understanding the pathophysiology and genetics of diabetes risk factors and its associated complications in South Asians is paramount to curbing the diabetes epidemic. With this understanding, the appropriate screening, preventative and therapeutic strategies can be implemented and further developed. In this review, we discuss in detail the biologic and lifestyle factors that predispose South Asians to diabetes and review the epidemiology and pathophysiology of microvascular and macrovascular complications of diabetes in South Asians. We also review the ongoing and completed diabetes prevention and management studies in South Asians.

Association of genetic variants with diabetic nephropathy

Diabetic nephropathy accounts for the most serious microvascular complication of diabetes mellitus. It is suggested that the prevalence of diabetic nephropathy will continue to increase in future posing a major challenge to the healthcare system resulting in increased morbidity and mortality. It occurs as a result of interaction between both genetic and environmental factors in individuals with both type 1 and type 2 diabetes. Genetic susceptibility has been proposed as an important factor for the development and progression of diabetic nephropathy, and various research efforts are being executed worldwide to identify the susceptibility gene for diabetic nephropathy. Numerous single nucleotide polymorphisms have been found in various genes giving rise to various gene variants which have been found to play a major role in genetic susceptibility to diabetic nephropathy. The risk of developing diabetic nephropathy is increased several times by inheriting risk alleles at susceptibility loci of various genes like ACE, IL, TNF-α, COL4A1, eNOS, SOD2, APOE, GLUT, etc. The identification of these genetic variants at a biomarker level could thus, allow the detection of those individuals at high risk for diabetic nephropathy which could thus help in the treatment, diagnosis and early prevention of the disease. The present review discusses about the various gene variants found till date to be associated with diabetic nephropathy.

Variations in CCR5, but not HFE, ELMO1, or SLC12A3, are associated with susceptibility to kidney disease in north Indian individuals with type 2 diabetes

BACKGROUND

Diabetic nephropathy (DN), the leading cause of end-stage renal disease worldwide, may have a genetic component. In the present study, we investigated variations in a set of genes with susceptibility to DN in a north Indian population.

METHODS

Four genes (HFE, ELMO1, SLC12A3, and CCR5) were selected on the basis of reported association with type 2 diabetes and nephropathy. In all, 417 diabetic subjects (215 without kidney disease [DM] and 202 with DN) and 197 healthy controls (HC) were evaluated for variations in HFE (845 G>A and 187G>C), SLC12A3 (g.34372G>A), CCR5 (59029A>G), and ELMO1 (+9170 G>A). Polymorphism analysis was performed by polymerase chain reaction-restriction fragment length polymorphism and Taqman allele discrimination assays.

RESULTS

Significant differences were found in genotype and allelic frequency in SLC12A3 (g.34372G>A) between diabetic subjects and HC (P < 0.03). There were no differences in the SLC12A3 g.34372G>A (AA+GA) genotype between diabetic subjects with and without nephropathy. However, the CCR5 59029AA genotype and A allele were significantly more frequent in diabetics compared with the HC (P = 0.01 and 0.03, respectively) and subjects with DN versus DM (P = 0.002 and 0.01, respectively). For ELMO1 (+9170 G>A), the GG genotype frequency was higher in the diabetic versus HC group. There were no differences in the frequency of HFE-845 G>A and HFE-187G>C among the groups.

CONCLUSION

This study shows that the CCR5 AA genotype is over-represented in subjects with kidney disease due to type 2 diabetes. The CCR5 59029G>A and ELMO1 (+9170 G>A) loci are more frequent, and the SLC12A3 34372 AA genotype is associated with a reduced risk of diabetes.

Association of Superoxide dismutases (SOD1 and SOD2) and Glutathione peroxidase 1 (GPx1) gene polymorphisms with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic disorder resulting from oxidative stress (OS), the root cause of insulin resistance, β-cell dysfunction, and impaired glucose tolerance. Antioxidant enzymes play key roles in cellular defense and can be used as important biomarkers for T2DM. The present study was undertaken to evaluate three genetic polymorphisms viz. SOD1 + 35A/C, SOD2 + 47C/T, and GPx + 599C/T in 207 T2DM cases and 210 healthy controls from North India. DNA was extracted from blood samples and genotyping was done by PCR-RFLP. Genotypic/allelic frequencies and haplotype/gene-gene interaction analysis were performed using SPSS (version 15.0) and SHEsis (v. online). Except age, all other biochemical parameters showed highly significant association in T2DM cases (P < 0.001). In North Indian population, SOD1 + 35A/C variant was monomorphic. Genotype/allele frequencies of SOD2 + 47C/T polymorphism and carriage rate of 'C' allele showed significant association (p < 0.05, < 0.001; OR 2.434). Genotype/allele frequencies of GPx1 + 599C/T and carriage rate showed no association although the odds ratio of GPx1 'C' allele indicated a 1.362 times higher risk of T2DM. SOD2 'CT' and GPx1 'CC' genotypes showed maximum association with biochemical parameters. Haplotype/gene-gene interaction analysis in controls and cases showed that SOD2 + 47C/T and GPx1 + 599C/T were in linkage disequilibrium (D: 0.168; r(2): 0.10) and individuals with this combination had a 1.273 times higher risk [OR; CI (95%)] of developing T2DM. Thus, we conclude that it is essential to assess the combinatorial association of gene variants with T2DM in order to identify risk haplotypes in a population.

Frequent extreme cold exposure and brown fat and cold-induced thermogenesis: a study in a monozygotic twin

INTRODUCTION

Mild cold acclimation is known to increase brown adipose tissue (BAT) activity and cold-induced thermogenesis (CIT) in humans. We here tested the effect of a lifestyle with frequent exposure to extreme cold on BAT and CIT in a Dutch man known as 'the Iceman', who has multiple world records in withstanding extreme cold challenges. Furthermore, his monozygotic twin brother who has a 'normal' sedentary lifestyle without extreme cold exposures was measured.

METHODS

The Iceman (subject A) and his brother (subject B) were studied during mild cold (13°C) and thermoneutral conditions (31°C). Measurements included BAT activity and respiratory muscle activity by [18F]FDG-PET/CT imaging and energy expenditure through indirect calorimetry. In addition, body temperatures, cardiovascular parameters, skin perfusion, and thermal sensation and comfort were measured. Finally, we determined polymorphisms for uncoupling protein-1 and β3-adrenergic receptor.

RESULTS

Subjects had comparable BAT activity (A: 1144 SUVtotal and B: 1325 SUVtotal), within the range previously observed in young adult men. They were genotyped with the polymorphism for uncoupling protein-1 (G/G). CIT was relatively high (A: 40.1% and B: 41.9%), but unlike during our previous cold exposure tests in young adult men, here both subjects practiced a g-Tummo like breathing technique, which involves vigorous respiratory muscle activity. This was confirmed by high [18F]FDG-uptake in respiratory muscle.

CONCLUSION

No significant differences were found between the two subjects, indicating that a lifestyle with frequent exposures to extreme cold does not seem to affect BAT activity and CIT. In both subjects, BAT was not higher compared to earlier observations, whereas CIT was very high, suggesting that g-Tummo like breathing during cold exposure may cause additional heat production by vigorous isometric respiratory muscle contraction. The results must be interpreted with caution given the low subject number and the fact that both participants practised the g-Tummo like breathing technique.

Nitric oxide system and diabetic nephropathy

About 30% of patients with type 2 diabetes mellitus develop clinically overt nephropathy. Hyperglycemia is necessary, but not sufficient, to cause the renal damage that leads to kidney failure. Diabetic nephropathy (DN) is a multifactorial disorder that results from interaction between environmental and genetic factors. In the present article we will review the role of the nitric oxide synthase (NOS) in the pathogenesis of DN.Nitric oxide (NO) is a short-lived gaseous lipophilic molecule produced in almost all tissues, and it has three distinct genes that encode three NOS isoforms: neuronal (nNOS), inducible (iNOS) and endothelial (eNOS).The correct function of the endothelium depends on NO, participating in hemostasis control, vascular tone regulation, proliferation of vascular smooth muscle cells and blood pressure homeostasis, among other features. In the kidney, NO plays many different roles, including control of renal and glomerular hemodynamics. The net effect of NO in the kidney is to promote natriuresis and diuresis, along with renal adaptation to dietary salt intake.The eNOS gene has been considered a potential candidate gene for DN susceptibility. Three polymorphisms have been extensively researched: G894T missense mutation (rs1799983), a 27-bp repeat in intron 4, and the T786C single nucleotide polymorphism (SNP) in the promoter (rs2070744). However, the potential link between eNOS gene variants and the induction and progression of DN yielded contradictory results in the literature.In conclusion, NOS seems to be involve in the development and progression of DN. Despite the discrepant results of many studies, the eNOS gene is also a good candidate gene for DN.

Endothelial nitric oxide synthase gene polymorphisms and risk of diabetic nephropathy: a systematic review and meta-analysis

Background

Nitric oxide (NO) has numerous functions in the kidney, including control of renal and glomerular hemodynamics, by interfering at multiple pathological and physiologically critical steps of nephron function. Endothelial NOS (eNOS) gene has been considered a potential candidate gene to diabetic nephropathy (DN) susceptibility. Endothelial nitric oxide synthase gene (eNOS-3) polymorphisms have been associated with DN, however some studies do not confirm this association. The analyzed polymorphisms were 4b/4a, T-786C, and G986T.

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement was used in this report. Case–control studies that had diabetic patients with DN as cases and diabetic patients without nephropathy as controls, as well as that evaluated at least one of the three polymorphisms of interest were considered eligible. All studies published up until December 31^st, 2012 were identified by searching electronic databases. Hardy-Weinberg equilibrium assessment was performed. Gene-disease association was measured using odds ratio estimation based on the following genetic contrast/models: (1) allele contrast; (2) additive model; (3) recessive model; (4) dominant model and (4) co-dominant model.

Results

Twenty-two studies were eligible for meta-analysis (4b/a: 15 studies, T-786C: 5 studies, and G984T: 12 studies). Considering 4b/a polymorphism, an association with DN was observed for all genetic models: allele contrast (OR = 1.14, CI: 1.04-1.25); additive (OR = 1.77, CI: 1.37-2.28); recessive (OR = 1.77, CI: 1.38-2,27); dominant (OR = 1.12, CI: 1.01-1.24), with the exception for co-dominance model. As well, T-786C polymorphism showed association with all models, with exception for co-dominance model: allele contrast (OR = 1.22, CI: 1.07-1.39), additive (OR = 1.52, CI: 1.18-1.97), recessive (OR = 1.50, CI: 1.16-1.93), and dominant (OR = 1.11, CI: 1.01-1.23). For the G894T polymorphism, an association with DN was observed in allelic contrast (OR = 1.12, CI: 1.03-1.25) and co-dominance models (OR = 1.13, CI: 1.04-1.37).

Conclusions

In the present study, there was association of DN with eNOS 4b/a and T-786C polymorphism, which held in all genetic models tested, except for co-dominance model. G894T polymorphism was associated with DN only in allele contrast and in co-dominance model. This data suggested that the eNOS gene could play a role in the development of DN.

Evaluation of glutathione S-transferase GSTM1 and GSTT1 deletion polymorphisms on type-2 diabetes mellitus risk

BACKGROUND

Due to the activity of GSTs in the detoxification of oxidative stress products, deletion polymorphisms of GSTM1 and GSTT1 may contribute to susceptibility to T2DM, since B-cells express very low levels of antioxidant enzymes. Recently, some studies have shown an association between GSTM1-null/GSTT1-null genotypes and an increased susceptibility to T2DM. A relationship between these polymorphisms and changes in the clinical parameters of diabetic patients has also been investigated. However, the results diverge considerably among the studies. Thus, this case-control study was designed to contribute to existing knowledge, as there are no studies on this issue performed in the Brazilian population.

METHODS AND FINDINGS

A total of 120 patients and 147 healthy individuals were included in this study. GSTT1 and GSTM1 deletion polymorphisms were genotyped by multiplex SYBR Green Real-Time PCR. The GSTT1-null genotype conferred a 3.2-fold increased risk to T2DM relative to the present genotype. There was no association between GSTM1-null and T2DM risk. In diabetic patients, GSTT1-null conferred higher levels of triglycerides and VLDL-cholesterol, while GSTM1-null was associated with increased levels of fasting blood glucose, glycated hemoglobin and blood pressure. We emphasized a necessity for applying log-linear analysis in order to explore an interaction between these polymorphisms properly.

CONCLUSION

These results suggest that the GSTT1 polymorphism may play an important role in the pathogenesis of T2DM in the Brazilian population. This gene could then be added to a set of genetic markers to identify individuals with an increased risk for developing T2DM and complications associated with dyslipidemia in diabetic patients. Although there was no association of GSTM1 deletion polymorphism with susceptibility to T2DM, the influence of this polymorphism on important clinical parameters related to glycemia and blood pressure levels was verified. This finding suggests that both GSTM1-null and GSTT1-null may contribute to the clinical course of T2DM patients.

Association of paraoxonase gene polymorphisms with diabetic nephropathy and retinopathy

Emerging reports have revealed a potential association of paraoxonase (PON) gene polymorphisms with diabetic nephropathy (DN) and diabetic retinopathy (DR). However, the identification of susceptible genes and the quantification of associated risks are elusive owing to a lack of reproducibility. Therefore, a meta‑analysis was conducted in the present study to improve the understanding of the effect of PON1 and PON2 on DN and DR. A total of 10 articles, involving 2,877 patients and 3,246 controls met the inclusion criteria. Functional variants (n=4) were evaluated, including rs662 (p.Q192R) and rs854560 (p.L55M) in PON1; and rs7493 (p.S311C) and rs12026 (p.A148G) in PON2. Overall, PON1‑L55M was found to be significantly associated with DR in all the genetic models: allele [odds ratio (OR)=2.42; 95% confidence interval (CI), 1.91‑3.07]; dominant (OR=5.76; 95% CI, 3.14‑10.55), homozygote (OR=10.53; 95% CI, 5.59‑19.86), heterozygote (OR=3.62; 95% CI, 1.94‑6.74), and recessive (OR=3.56; 95% CI, 2.61‑4.86), with no evidence of between‑study heterogeneity. However, such associations were not detected in DN and the other three polymorphisms did not show any associations with DN or DR. The current meta‑analysis highlighted results for the risk of association of PON1‑55L with DR. The results also indicated that PON2 gene polymorphisms, as well as PON1‑Q192R, may not confer major genetic risk to DN or DR. Additional studies are required to enrich the understanding of PON genes, particularly for its functional role in DR.

Null genotypes of GSTM1 and GSTT1 contribute to increased risk of diabetes mellitus: a meta-analysis

Diabetes mellitus (DM) is a common disease which results from various causes including genetic and environmental factors. Glutathione S-Transferase M1 (GSTM1) and Glutathione S-Transferase T1 (GSTT1) genes are polymorphic in human and the null genotypes lead to the absence of enzyme function. Many studies assessed the associations between GSTM1/GSTT1 null genotypes and DM risk but reported conflicting results. In order to get a more precise estimate of the associations of GSTM1/GSTT1 null genotypes with DM risk, we performed this meta-analysis. Published literature from PubMed, Embase and China Biology Medicine (CBM) databases was searched for eligible studies. Pooled odds ratios (OR) and corresponding 95% confidence intervals (95%CI) were calculated using a fixed- or random-effects model. 11 publications (a total of 2577 cases and 4572 controls) were finally included into this meta-analysis. Meta-analyses indicated that null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1-GSTT1 were all associated with increased risk of DM (GSTM1: OR random-effects=1.60, 95%CI 1.10-2.34, POR=0.014; GSTT1: OR random-effects=1.47, 95%CI 1.12-1.92, POR=0.005; GSTM1-GSTT1: OR fixed-effects=1.83, 95%CI 1.30-2.59, POR=0.001). Subgroup by ethnicity suggested significant associations between null genotypes of GSTM1 and GSTT1 and DM risk among Asians (GSTM1: OR random-effects=1.77, 95%CI 1.24-2.53, POR=0.002; GSTT1: OR random-effects=1.58, 95%CI 1.09-2.27, POR=0.015). This meta-analysis suggests null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1-GSTT1 are all associated with increased risk of DM, and null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1-GSTT1 are potential biomarkers of DM.

Glutathione S-transferase A1, M1, P1 and T1 null or low-activity genotypes are associated with enhanced oxidative damage among haemodialysis patients

BACKGROUND

Increased oxidative stress is a hallmark of end-stage renal disease (ESRD). Glutathione S-transferases (GST) are involved in the detoxification of xenobiotics and protection of oxidative damage. We hypothesized that genetic polymorphism in antioxidant enzymes GSTA1, GSTM1, GSTP1 and GSTT1 is more frequent in ESRD and modulates the degree of oxidative stress in these patients.

METHODS

GSTA1, GSTM1, GSTP1 and GSTT1 genotypes were determined in 199 ESRD patients and 199 age- and gender-matched controls. Markers of protein and lipid oxidative damage [thiol groups, carbonyl groups, advanced oxidative protein products, nitrotyrosine, malondialdehyde (MDA) and MDA adducts], together with total oxidant status and pro-oxidant-antioxidant balance were determined.

RESULTS

Individual GST polymorphisms influence vulnerability to both protein and lipid oxidation, with GSTM1-null gene variant having the most pronounced effect. Furthermore, a strong combined effect of null/low-activity GSTM1, GSTT1, GSTA1 and GSTP1 genotypes in terms of susceptibility towards oxidative and carbonyl stress was found in ESRD patients. When patients were stratified according to GSTM1 and GSTT1, the highest oxidant damage was noted in those with the GSTM1-null/GSTT1-null genotype. The observed effect was even stronger in patients with the third low-activity GSTP1 or GSTA1 genotype. Finally, the level of oxidative and carbonyl stress was most pronounced in the subgroup of patients with all four null or low-activity GSTM1, GSTT1, GSTP1 and GSTA1 genotypes.

CONCLUSIONS

According to the GST genotype, ESRD patients may be stratified in terms of the level of oxidative and carbonyl stress that might influence cardiovascular prognosis, but could also improve efforts towards individualization of antioxidant treatment.

Antidiabetic effects of Justicia spicigera Schltdl (Acanthaceae)

ETHNOPHARMACOLOGICAL IMPORTANCE

Justicia spicigera is a plant species used for the Teenak (Huesteca Potosina) and Mayan (Yucatan peninsula) indigenous for the empirical treatment of diabetes, infections and as stimulant.

AIM OF THE STUDY

To evaluate the cytotoxicity, antioxidant and antidiabetic properties of J. spicigera.

MATERIALS AND METHODS

The effects of ethanolic extracts of J. spicigera (JSE) on the glucose uptake in insulin-sensitive and insulin-resistant murine 3T3-F442A and human subcutaneous adipocytes was evaluated. The antioxidant activities of the extract of JSE was determined by ABTS and DPPH methods. Additionally, it was evaluated the antidiabetic properties of JSE on T2DM model.

RESULTS

JSE stimulated 2-NBDG uptake by insulin-sensitive and insulin-resistant human and murine adipocytes in a concentration-dependent manner with higher potency than rosiglitazone 1mM. JSE showed antioxidant effects in vitro and induced glucose lowering effects in normoglycemic and STZ-induced diabetic rats.

CONCLUSION

The antidiabetic effects of administration of J. spicigera are related to the stimulation of glucose uptake in both insulin-sensitive and insulin-resistant murine and human adipocytes and this evidence justify its empirical use in Traditional Medicine. In addition, J. spicigera exerts glucose lowering effects in normoglycemic and STZ-induced diabetic rats.

Glutathione S-transferase gene polymorphisms are not major risks for susceptibility to posttransplantation diabetes mellitus in Taiwan renal transplant recipients

Glutathione S-transferase (GST) M1 null genotype has been reported playing a significant role in the diabetes mellitus (DM) susceptibility in Turkish population. We investigated whether the GSTM1, GSTA1, and GSTP1 gene polymorphisms are associated with posttransplantation diabetes mellitus (PTDM) in Taiwan. There were 283 renal transplant recipients (RTRs) enrolled. Polymerase chain reaction-restriction fragment length polymorphism was used for the measurement of GSTA1, M1, and P1 genetic polymorphisms. PTDM was diagnosed according to the American Diabetes Association guidelines. Eight-five patients (30%) were diagnosed with PTDM. The averaged posttransplant follow-up period was 77.9 ± 27.2 months. Duration from transplantat to diagnosis of PTDM ranged from 0.2 to 103.1 months (19.2 ± 26.3 months). There were significantly differences between non-DM and PTDM groups in age (50.6 ± 11.0 vs. 54.6 ± 9.36 years, P = 0.005), BMI (22.4 ± 3.6 vs. 24.3 ± 3.8, P<0.001). The distributions of GSTA1, GSTP1, and GSTM1 genotypes alleles were not significantly different between PTDM and non-DM group. Patients carrying the different GSTA1, GSTP1, and GSTM1 genetic and allelic polymorphisms had no differences for the development of PTDM. These overall results suggested a lack of strong association with GSTA1, GSTP1, and GSTM1 genetic polymorphisms to the susceptibility of PTDM in Taiwanese RTRs.

DNA methylation profiling identifies epigenetic dysregulation in pancreatic islets from type 2 diabetic patients

In addition to genetic predisposition, environmental and lifestyle factors contribute to the pathogenesis of type 2 diabetes (T2D). Epigenetic changes may provide the link for translating environmental exposures into pathological mechanisms. In this study, we performed the first comprehensive DNA methylation profiling in pancreatic islets from T2D and non-diabetic donors. We uncovered 276 CpG loci affiliated to promoters of 254 genes displaying significant differential DNA methylation in diabetic islets. These methylation changes were not present in blood cells from T2D individuals nor were they experimentally induced in non-diabetic islets by exposure to high glucose. For a subgroup of the differentially methylated genes, concordant transcriptional changes were present. Functional annotation of the aberrantly methylated genes and RNAi experiments highlighted pathways implicated in β-cell survival and function; some are implicated in cellular dysfunction while others facilitate adaptation to stressors. Together, our findings offer new insights into the intricate mechanisms of T2D pathogenesis, underscore the important involvement of epigenetic dysregulation in diabetic islets and may advance our understanding of T2D aetiology.

Investigation of heavy metal effects on immobilized paraoxanase by glutaraldehyde

Serum paraoxonase 1 (PON1) was purified from bovine serum using hydrophobic interaction chromotography on Sepharose 4B-coupled l-tyrosine 1-naphthylamine gel, and monitored by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Paraoxonase enzyme was immobilized using different ratios of glutaraldehyde and the maximum activity was observed with 7% glutaraldehyde. The effects of inhibition by Mn(+2), Co(+2) and Cu(+2) heavy metals on the immobilized and free enzyme activities were studied. At the optimum pH and temperature, the K(m) and V(max) kinetic values for bovine serum paraoxonase and immobilized paraoxonase towards paraoxon substrate were determined as 0.296 × 10(-3) M & 37.04 EU vs. 0.727-10(-3) M & 36.36 EU, respectively.

Genome-wide association studies of chronic kidney disease: what have we learned?

The past 3 years have witnessed a dramatic expansion in our knowledge of the genetic determinants of estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD). However, heritability estimates of eGFR indicate that we have only identified a small proportion of the total heritable contribution to the phenotypic variation. The majority of associations reported from genome-wide association studies identify genomic regions of interest and further work will be required to identify the causal variants responsible for a specific phenotype. Progress in this area is likely to stem from the identification of novel risk genotypes, which will offer insight into the pathogenesis of disease and potential novel therapeutic targets. Follow-up studies stimulated by findings from genome-wide association studies of kidney disease are already yielding promising results, such as the identification of an association between urinary uromodulin levels and incident CKD. Although this work is at an early stage, prospects for progress in our understanding of CKD and its treatment look more promising now than at any point in the past.

Association of the C47T polymorphism in SOD2 with diabetes mellitus and diabetic microvascular complications: a meta-analysis

AIMS/HYPOTHESIS

A meta-analysis was performed to assess the association of C47T (rs4880) (also called Val16Ala) polymorphism in SOD2 gene with reduced risk of diabetes mellitus, including type 1 and type 2 diabetes, and diabetic microvascular complications (DMI) including diabetic nephropathy, diabetic retinopathy and diabetic polyneuropathy.

METHODS

A comprehensive search was conducted to identify all case-control or cohort design studies of the above-mentioned associations. The fixed or random effect pooled measure was selected on the basis of homogeneity test among studies. Heterogeneity among studies was evaluated using the I (2). Meta-regression and the 'leave one out' sensitive analysis of Patsopoulos et al. were used to explore potential sources of between-study heterogeneity. Publication bias was estimated using modified Egger's linear regression test as proposed by Harbord et al.

RESULTS

Seventeen articles were included. After excluding articles that deviated from Hardy-Weinberg equilibrium in cases and/or in controls, and were also the key contributors to between-study heterogeneity, the meta-analysis showed a significant association of the C allele with reduced risk of DMI in dominant (OR 0.788, 95% CI 0.680-0.914), recessive (OR 0.808, 95% CI 0.685-0.953) and codominant (OR 0.828, 95% CI 0.751-0.913) models. It also showed a significant association with reduced risk of diabetic nephropathy in the dominant model (OR 0.801, 95% CI 0.664-0.967), and reduced risk of diabetic retinopathy in the dominant (OR 0.601, 95% CI 0.423-0.855), recessive (OR 0.548, 95% CI 0.369-0.814) and codominant (OR 0.651, 95% CI 0.517-0.820) models.

CONCLUSIONS/INTERPRETATION

The meta-analysis suggested that C allele of C47T polymorphism in SOD2 gene has protective effects on risk of DMI, diabetic nephropathy and diabetic retinopathy. This risk needs to be confirmed by further studies.

Association of eNOS gene polymorphisms with renal disease in Caucasians with type 2 diabetes

AIM

In this study we investigated if the -786T>C, the VNTR intron 4 a/b and the 894G>T (Glu298Asp) polymorphisms in the eNOS gene were associated with renal disease in 617 type 2 diabetic Caucasian-Brazilians. These polymorphisms were also examined in 100 Caucasian healthy blood donors.

METHODS

Genotyping of eNOS polymorphisms was performed by PCR or PCR-RFLP and haplotype frequencies were estimated using a Bayesian method. Logistic regression analysis was done to test for association of eNOS polymorphisms with susceptibility to renal involvement (microalbuminuria, macroalbuminuria or end-stage renal disease). This analysis was carried out assuming three different genetic models for the minor allele, adjusting for possible effect modifiers.

RESULTS

Genotype and allele frequencies in patients with renal disease were not significantly different from those of patients with normoalbuminuria and healthy blood donors for all eNOS polymorphisms. Likewise, there were no differences in haplotype frequencies among healthy blood donors and type 2 diabetic patients with or without renal involvement (P>0.05 for all comparisons).

CONCLUSION

No associations between the -786T>C, the VNTR intron 4 a/b and the 894G>T (Glu298Asp) polymorphisms in the eNOS gene and renal disease were observed in type 2 diabetic Caucasian-Brazilians.

GSTP1 Ile105Val Polymorphism in Serbian Patients with Pancreatic Diseases

The aim of the current preliminary case-control study was to identify glutathione S-transferase P1 (GSTP1) Ile105Val allele and genotype frequency and to evaluate its impact on susceptibility to pancreatic diseases in a Serbian population. This study has encompassed 157 patients with three major types of chronic pancreatic pathology: 47 with pancreatic cancer, 50 with chronic pancreatitis and 60 with type 2 diabetes mellitus, as well as 107 healthy individuals. The presence of GSTP1 Ile105Val polymorphism was analyzed using a PCR-RFLP method. Allele 105Val was less frequent in patients with pancreatic cancer (24.5%) and chronic pancreatitis (24.0%) and slightly more frequent in patients with type 2 diabetes mellitus (31.7%) in comparison to healthy individuals (29.9%), but the differences were not statistically significant. Distribution of Ile105Val polymorphism genotypes differed between the analyzed groups, but differences were also not statistically significant. There are only a few studies regarding the role of GSTP1 Ile105Val polymorphism in pancreatic diseases and their results are inconsistent. The significance of GSTP1 Ile105Val polymorphism for pancreatic pathology remains unclear and further studies are needed in order to elucidate its role in pancreatic diseases.

Polymorphisms of eNOS gene are associated with diabetic nephropathy: a meta-analysis

The aim of the current study is to assess the association between the alleles of endothelial nitric oxide synthases (eNOS) gene 4b/a, G894T, T786C polymorphisms and diabetic nephropathy (DN) through meta-analyses. We also performed a subgroup analysis based on ethnicity (Caucasians, East-Asian and other populations). A total of 3793 patients (DN) and 3161 controls (diabetes without nephropathy) for 4b/a, 2654 patients and 1993 controls for G894T and 1348 patients and 1175 controls for T786C were included in our analysis. Overall, allele contrast (4a versus 4b) of 4b/a polymorphism produced significant results in the global population [random effects model (RE) odds ratio (OR) = 1.33; 95% confidence interval (CI) = 1.10-1.61, P = 0.003] and East-Asian population (RE OR = 1.68; 95% CI = 1.23-2.30, P = 0.001), but not in the Caucasian population. In allele contrast of G894T, an obvious significant result was observed in the East-Asian population [fixed effects model OR = 1.69; 95% CI = 1.37-2.08, P < 0.0001], but not in the Caucasian population. Sensitivity analyses generated similar results to those of the primary analyses. The evidence accumulated suggested that 4b/a and G894T polymorphisms in the eNOS gene were associated with susceptibility to DN in Asian populations, but not in Caucasian populations.

Sodium-glucose transport: role in diabetes mellitus and potential clinical implications

PURPOSE OF REVIEW

Current options for glycemic control are less than optimal in terms of efficacy and to reduce complications in the diabetic population. Selective inhibition of SGLT2 in the proximal tubule increases urinary glucose excretion thereby reducing plasma glucose levels, which may present a novel therapeutic approach.

RECENT FINDINGS

SGLT2 inhibitors enhance glucose excretion and improve glycemic control in patients with type 2 diabetes in the absence of clinically relevant hypoglycemia or sustained changes in volume status or glomerular filtration rate. This is associated with lowering of body weight and may reduce systolic blood pressure. The increased glucosuria appears to increase the risk of genital infections but may not increase the risk of urinary tract infections.

SUMMARY

The ability of SGLT2 inhibitors to reduce plasma glucose without inducing increased insulin secretion, clinically relevant hypoglycemia, or weight gain constitutes a major advance. The ability to increase glucose excretion provides a powerful means to treat caloric excess conditions. Important questions remain to be resolved and more clinical research is needed on the long-term effects of SGLT2 inhibition. Potential extrarenal effects need to be explored in order to determine the safety of these compounds. It also remains to be determined whether these drugs lower the toxicity of glucose directly on renal cells, independent of hyperglycemia, which may slow or prevent the progressive nature of diabetic nephropathy.

Association analysis of ADPRT1, AKR1B1, RAGE, GFPT2 and PAI-1 gene polymorphisms with chronic renal insufficiency among Asian Indians with type-2 diabetes

BACKGROUND

To determine association of nine single nucleotide polymorphisms (SNPs) in ADP ribosyltransferase-1 (ADPRT1), aldo-keto reductase family 1 member B1 (AKR1B1), receptor for advanced glycation end-products (RAGE), glutamine:fructose-6-phosphate amidotransferase-2 (GFPT2), and plasminogen activator inhibitor-1 (PAI-1) genes with chronic renal insufficiency (CRI) among Asian Indians with type 2 diabetes; and to identify epistatic interactionss between genes from the present study and those from renin-angiotensin-aldosterone system (RAAS), and chemokine-cytokine, dopaminergic and oxidative stress pathways (previously investigated using the same sample set).

METHODS

Type 2 diabetes subjects with CRI (serum creatinine > or =3.0 mg/dl) constituted the cases (n = 196), and ethnicity and age matched individuals with diabetes for a duration of > or = 10 years, normal renal functions and normoalbuminuria recruited as controls (n = 225). Allelic and genotypic constitution of 10 polymorphisms (SNPs) from five genes namely--ADPRT1, AKR1B1, RAGE, GFPT2 and PAI-1 with diabetic CRI was investigated. The genetic associations were evaluated by computation of odds ratio and 95% confidence interval. Multiple logistic regression analysis was carried out to correlate various clinical parameters with genotypes, and to study epistatic interactions between SNPs in different genes.

RESULTS

Single nucleotide polymorphisms -429 T>C in RAGE and rs7725 C>T SNP in 3' UTR in GFPT2 gene showed a trend towards association with diabetic CRI. Investigation using miRBase statistical tool revealed that rs7725 in GFPT2 was a perfect target for predicted miRNA (hsa miR-378) suggesting the presence of the variant 'T' allele may result in an upregulation of GFPT2 contributing to diabetic renal complication. Epistatic interaction between SNPs in transforming growth factor TGF-beta1 (investigated using the same sample set and reported elsewhere) and GFPT2 genotype was observed.

CONCLUSIONS

Association of SNPs in RAGE and GFPT2 suggest that the genes involved in modulation of oxidative pathway could be major contributor to diabetic chronic renal insufficiency. In addition, GFPT2 mediated overproduction of TGF-beta1 leading to endothelial expansion and thereby CRI seems likely, suggested by our observation of a significant interaction between GFPT2 with TGF-beta1 genes. Further, identification of predicted miRNA targets spanning the associated SNP in GFPT2 implicates the rs7725 SNP in transcriptional regulation of the gene, and suggests GFPT2 could be a relevant target for pharmacological intervention. Larger replication studies are needed to confirm these observations.