Genetic polymorphisms in genes encoding antioxidant enzymes are associated with diabetic retinopathy in type 1 diabetes

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 of glutathione S-transferase M1 and T1 polymorphisms on the susceptibility of diabetic retinopathy in the Bangladeshi population

Objectives

This study investigated the role of glutathione-S-transferase gene (GSTM1 and GSTT1) polymorphisms in the predisposition of type 2 diabetes mellitus (T2DM) with or without diabetic retinopathy (DR).

Methods

The case-control study included 188 subjects: 50 T2DM with DR, 63 T2DM without DR, and 75 healthy individuals' presenting no clinical signs or evidence of diabetes mellitus. Zinc and magnesium levels were measured using a flame atomic absorption spectrophotometer, and the lipid profile was evaluated using standard methods. The gene polymorphism of GSTs was performed by the multiplex-PCR method.

Results

Compared to the control, DR and T2DM had considerably greater total cholesterol, LDL-C, and decreased HDL-C levels. Magnesium levels were significantly lower in DR and T2DM than in control. Total cholesterol, LDL, TG, and magnesium levels didn't differ significantly between DR and T2DM groups. In DR, the GSTT1-null genotype was more prevalent than in T2DM subjects and controls (26.0%, 12.7%, and 10.7%, respectively). GSTT1-null genotype was considerably more common in DR than in controls and associated with 2.94-folds enhancing the chance of developing DR (OR = 2.94; 95% CI = 1.12-7.75; p = 0.02). However, the recurrence of GSTM1-null genotype was not clearly distinguishable among these three populations (28.0%, 38.1% and 29.3%, respectively) and not particularly prone to the risk of DR compared to T2DM subjects and controls (OR = 0.63; 95% CI = 0.28-1.41; p = 0.26; OR = 0.94; 95% CI = 0.42-2.07; p = 0.87, respectively).

Conclusions

Taken together, these findings suggest the potential role of GSTT1 deletion mutation as a risk factor for the vulnerability of DR among T2DM patients in the Bangladeshi population.

Perceived Age as a Mortality and Comorbidity Predictor: A Systematic Review

INTRODUCTION

Perceived age is defined as how old a person looks to external evaluators. It reflects the underlying biological age, which is a measure based on physical and physiological parameters reflecting a person's aging process more accurately than chronological age. People with a higher biological age have shorter lives compared to those with a lower biological age with the same chronological age. Our review aims to find whether increased perceived age is a risk factor for overall mortality risk or comorbidities.

METHODS

A literature search of three databases was conducted following the PRISMA guidelines for studies analyzing perceived age or isolated facial characteristics of old age and their relationship to mortality risk or comorbidity outcomes. Data on the number of patients, type and characteristics of evaluation methods, evaluator characteristics, mean chronologic age, facial characteristics studied, measured outcomes, and study results were collected.

RESULTS

Out of 977 studies, 15 fulfilled the inclusion criteria. These studies found an increase in mortality risk of 6-51% in older-looking people compared to controls (HR 1.06-1.51, p < 0.05). In addition, perceived age and some facial characteristics of old age were also associated with cardiovascular risk and myocardial infarction, cognitive function, bone mineral density, and chronic obstructive pulmonary disease (COPD).

CONCLUSION

Perceived age promises to be a clinically useful predictor of overall mortality and cardiovascular, pulmonary, cognitive, and osseous comorbidities.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The GSTO2 (rs156697) Polymorphism Modifies Diabetic Nephropathy Risk

Background and Objectives: In the development of type 2 diabetes mellitus (T2DM) and its complications, genetic and environmental factors play important roles. Diabetic nephropathy (DN), one of the major microangiopathic chronic diabetic complications, is associated with an increased risk of major cardiovascular events and all-cause mortality. The present study was designed to investigate the possible modifying effect of glutathione transferase polymorphisms (GSTM1, GSTT1, GSTP1 rs1138272/rs1695, GSTO1 rs4925 and GSTO2 rs156697) in the susceptibility to T2DM and diabetic nephropathy. Materials and Methods: GSTM1 and GSTT1 deletion polymorphisms were determined by multiplex PCR, whereas GSTO1, GSTO2, and GSTP1 polymorphisms were determined by the real-time PCR in 160 T2DM patients and 248 age- and gender-matched controls. Advanced glycation end products (AGEs) were measured by ELISA. Results: Among six investigated GST polymorphisms, a significant association between the GST genotypes and susceptibility for development of diabetes mellitus was found for the GSTM1, GSTT1, GSTP1 (rs1138272) and GSTO1 polymorphisms. When the GST genotypes’ distribution in diabetes patients was assessed in the subgroups with and without diabetic nephropathy, a significant association was found only for the GSTO2 rs156697 polymorphism. Diabetic patients, carriers of the GSTM1 null, GSTT1 null and variant GSTO1*AA genotypes, had significantly increased levels of AGEs in comparison with carriers of the GSTM1 active, GSTT1 active and referent GSTO1*CC genotypes (p < 0.001, p < 0.001, p = 0.004, respectively). Conclusions: The present study supports the hypothesis that GST polymorphisms modulate the risk of diabetes and diabetic nephropathy and influence the AGEs concentration, suggesting the potential regulatory role of these enzymes in redox homeostasis disturbances.

Association of Polymorphisms in Antioxidant Enzyme-Encoding Genes with Diabetic Nephropathy in a Group of Saudi Arabian Patients with Type II Diabetes Mellitus

Introduction

Purpose

Patients and Methods

Results

Conclusion

Re-emerging concepts of immune dysregulation in autism spectrum disorders

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by communication and social interaction deficits, and by restricted interests and stereotyped, repetitive behavior patterns. ASD has a strong genetic component and a complex architecture characterized by the interplay of rare and common genetic variants. Recently, increasing evidence suggest a significant contribution of immune system dysregulation in ASD. The present paper reviews the latest updates regarding the altered immune landscape of this complex disorder highlighting areas with potential for biomarkers discovery as well as personalization of therapeutic approaches. Cross-talk between the central nervous system and immune system has long been envisaged and recent evidence brings insights into the pathways connecting the brain to the immune system. Disturbance of cytokine levels plays an important role in the establishment of a neuroinflammatory milieu in ASD. Several other immune molecules involved in antigen presentation and inflammatory cellular phenotypes are also at play in ASD. Maternal immune activation, the presence of brain-reactive antibodies and autoimmunity are other potential prenatal and postnatal contributors to ASD pathophysiology. The molecular players involved in oxidative-stress response and mitochondrial system function, are discussed as contributors to the pro-inflammatory pattern. The gastrointestinal inflammation pathways proposed to play a role in ASD are also discussed. Moreover, the body of evidence regarding some of the genetic factors linked to the immune system dysregulation is reviewed and discussed. Last, but not least, the epigenetic traits and their interactions with the immune system are reviewed as an expanding field in ASD research. Understanding the immune-mediated pathways that influence brain development and function, metabolism, and intestinal homeostasis, may lead to the identification of robust diagnostic or predictive biomarkers for ASD individuals. Thus, novel therapeutic approaches could be developed, ultimately aiming to improve their quality of life.

Evaluation of glutathione S-transferase polymorphism in Iranian patients with type 2 diabetic microangiopathy

Background

Overproduction of reactive oxygen species as a result of hyperglycemia in diabetes mellitus leads to microvascular complications. Glutathione S-transferases play important detoxifying roles with antioxidant potentials. This study aimed to assess whether the glutathione S-transferase M1 and T1 genotypes were associated with type 2 diabetes mellitus microangiopathic complications in the Iranian population.

Results

In this case-control study, the frequencies of null GSTM1 and GSTT1 genotypes were 4/72 (5.56%) and 12/72 (16.67%) respectively, in uncomplicated DM group. The frequencies of null GSTM1 and GSTT1 genotype in complicated DM group were 16/134 (11.94%) and 37/134 (27.61%), respectively. The proportion of GSTM1 null genotypes was higher in diabetic nephropathy compared to non-nephropathy (19.3% vs. 6.04 %, P = 0.006). At GSTT1 locus, patients with diabetic peripheral neuropathy had a higher frequency of deletion compared to those of without neuropathy (30.39% vs. 23.49%) (P = 0.02).

Conclusion

Selective polymorphisms encoding GSTM1 and GSTT1genes may prove useful as genetic markers to recognize individuals with an increased trend in developing diabetic nephropathy and neuropathy, respectively. This will help better identify individuals at higher risk toward microvascular complications of type 2 diabetes due to genetic susceptibility.

Riding the tiger - physiological and pathological effects of superoxide and hydrogen peroxide generated in the mitochondrial matrix

Elevated mitochondrial matrix superoxide and/or hydrogen peroxide concentrations drive a wide range of physiological responses and pathologies. Concentrations of superoxide and hydrogen peroxide in the mitochondrial matrix are set mainly by rates of production, the activities of superoxide dismutase-2 (SOD2) and peroxiredoxin-3 (PRDX3), and by diffusion of hydrogen peroxide to the cytosol. These considerations can be used to generate criteria for assessing whether changes in matrix superoxide or hydrogen peroxide are both necessary and sufficient to drive redox signaling and pathology: is a phenotype affected by suppressing superoxide and hydrogen peroxide production; by manipulating the levels of SOD2, PRDX3 or mitochondria-targeted catalase; and by adding mitochondria-targeted SOD/catalase mimetics or mitochondria-targeted antioxidants? Is the pathology associated with variants in SOD2 and PRDX3 genes? Filtering the large literature on mitochondrial redox signaling using these criteria highlights considerable evidence that mitochondrial superoxide and hydrogen peroxide drive physiological responses involved in cellular stress management, including apoptosis, autophagy, propagation of endoplasmic reticulum stress, cellular senescence, HIF1α signaling, and immune responses. They also affect cell proliferation, migration, differentiation, and the cell cycle. Filtering the huge literature on pathologies highlights strong experimental evidence that 30-40 pathologies may be driven by mitochondrial matrix superoxide or hydrogen peroxide. These can be grouped into overlapping and interacting categories: metabolic, cardiovascular, inflammatory, and neurological diseases; cancer; ischemia/reperfusion injury; aging and its diseases; external insults, and genetic diseases. Understanding the involvement of mitochondrial matrix superoxide and hydrogen peroxide concentrations in these diseases can facilitate the rational development of appropriate therapies.

Clinical variables and ethnicity may influenced by polymorphism of CAT -262C/T and MnSOD 47C/T antioxidant enzymes in Algerian type1 diabetes without complications

The latest studies in Algeria show that the frequency of type 1 diabetes (T1D) without complications is lower than that with complications and represents a significant burden in terms of cost and treatment. For this reason, we are interested in uncomplicated type1 diabetes and risk factors that are related to polymorphisms of antioxidant enzymes in order to prevent its complications. A total of 260 blood samples of young Algerian adults were examined. The genotypic analysis of Catalase gene (CAT -262C/T, rs1001179) and the superoxide dismutase gene (MnSOD 47C/T, rs4880) was performed by real-time PCR using TaqMan technology. The genotypic distribution of the CAT -262C/T promoter gene's polymorphism showed a significant difference between control and T1D patients for the CC genotype (p = 0.009; OR = 0.30) and for the T allele (p = 0.002; OR = 2.82). In addition, the genotypic distribution of the MnSOD 47C/T gene showed an association with T1D for the CT genotype (p = 0.040; OR = 2.37). Our results revealed that polymorphisms of CAT and MnSOD may be associated with physiopathology causing the onset of T1D. Our data, suggest that the genotypic frequencies of these SNPs appear to be influenced by clinical variables and by the Arab-Berber ethnic origin of the Algerian population.

Association of Polymorphisms in CYBA, SOD1, and CAT Genes with Type 1 Diabetes and Diabetic Peripheral Neuropathy in Children and Adolescents

AIMS

The aim of our study was to investigate possible associations between three SNPs: rs4673 in the CYBA gene; rs1041740 in the SOD1 gene; and rs1001179 in the CAT gene, and type 1 diabetes (T1D) or diabetic peripheral neuropathy (DPN) in T1D patients.

MATERIALS AND METHODS

Allelic variants of the selected SNPs were determined by allelic discrimination assays in 114 T1D patients enrolled in the study group and in 90 healthy individuals from a control group. Associations between each of the three SNPs were tested in subgroups of T1D patients divided according to the presence of DPN.

RESULTS

The TT genotype of rs4673 in the CYBA gene was associated with DPN in T1D patients (OR 4.997, 95% CI 1.403-19.083, p = 0.016). Weak significance was observed for a protective effect of the TT genotype of rs1041740 in the SOD1 gene relative to T1D development (OR 0.318, 95% CI 0.092-0.959, p = 0.056). There was no significant association between the CAT gene SNP rs1001179 and T1D or DPN.

CONCLUSION

We showed a strong association of the CYBA polymorphism rs4673 with DPN in Slovak children and adolescents with T1D. Further studies are necessary to assess the relationship between rs1041740 and T1D or DPN.

Gene Polymorphisms of Glutathione S-Transferase T1/M1 in Egyptian Children and Adolescents with Type 1 Diabetes Mellitus

OBJECTIVE

Oxidative stress plays an important role in the pathogenesis of type 1 diabetes mellitus (T1DM). To evaluate the association of glutathione S-transferase mu 1 (GST M1) and glutathione S-transferase theta 1 (GST T1) polymorphisms with development of T1DM and disease-related risk factors.

METHODS

Measurement of fasting glucose, serum creatinine, lipid profile, and glycosylated hemoglobin (HbA1c), as well as evaluation of GST T1 and M1 genetic polymorphisms using polymerase chain reaction were done in 64 diabetic children and 41 controls.

RESULTS

The diabetic group had significantly higher fasting glucose, HbA1c, and cholesterol levels. GST T1 null genotype was more frequent in the diabetic than the control group with 4.2-fold increased risk of T1DM (odds ratio=4.2; 95% confidence interval=1.6-11.5; p=0.03). Significant positive associations were found with lipid profile, HbA1c, and duration of illness but not with age, age at onset, and body mass index.

CONCLUSION

Gene polymorphisms of the enzyme GST are associated with development of T1DM and disease-related risk factors.

MnSOD Val16Ala polymorphism associated with retinopathy risk in diabetes: a PRISMA-compliant Meta-analysis of case-control studies

AIM

To investigate the association of Manganese superoxide dismutase (MnSOD) Val16Ala polymorphism with diabetic retinopathy (DR).

METHODS

PubMed, Embase, China National Knowledge Infrastructure, and Wanfang databases were searched. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the association. Subgroup, sensitivity, and cumulative analyses were performed. Publication bias was also analyzed.

RESULTS

Eight studies were included in the pooled analysis. The MnSOD Val16Ala polymorphism was associated with the risk of DR under the dominant model (OR=0.66, 95%CI=0.48-0.91, P<0.0001), this result was demonstrated to be relatively stable in cumulative analysis. No significant publication bias was found. This polymorphism was also associated with the risk of DR in Caucasians under the dominant model (OR=0.64, 95%CI=0.42-0.97, P=0.04,) and in Asians under the recessive model (OR=0.31, 95%CI=0.11-0.88, P=0.03).

CONCLUSION

These findings suggest that the MnSOD Val16Ala polymorphism is a risk factor for DR, and that more attention should be paid to carriers of these susceptibility genes.

The effects of rosuvastatin on lipid-lowering, inflammatory, antioxidant and fibrinolytics blood biomarkers are influenced by Val16Ala superoxide dismutase manganese-dependent gene polymorphism

Rosuvastatin is a cholesterol-lowering drug that also attenuates the inflammatory process and oxidative stress via the reduction of superoxide anion production. Superoxide anions are metabolized by manganese-dependent superoxide dismutase (MnSOD or SOD2) in the mitochondria. In humans, there is a gene polymorphism where a change of alanine (Ala) to valine (Val) occurs at the 16th amino acid (Ala16Val-SOD2). The VV genotype has been associated with the risk of developing several metabolic diseases, such as hypercholesterolemia. Thus, to further explore this phenomenon, this study investigated the influence of the Val16Ala-SOD2 polymorphism on the lipid profile and inflammatory and fibrinolytic biomarkers of 122 hypercholesterolemic patients undergoing the first pharmacological cholesterol-lowering therapy who were treated with 20 mg rosuvastatin for 120 days. The findings indicate that the VV patients who present a low-efficiency SOD2 enzyme exhibit an attenuated response to rosuvastatin compared with the A-allele patients. The effect of rosuvastatin on inflammatory and fibrinolytic biomarkers was also less intense in the VV patients. These results suggest some pharmacogenetic effects of Val16Ala-SOD2 in hypercholesterolemia treatment.

Influence of GSTM1, GSTT1, and GSTP1 Polymorphisms on Type 2 Diabetes Mellitus and Diabetic Sensorimotor Peripheral Neuropathy Risk

BACKGROUND AND AIMS

Diabetic neuropathy is a frequent complication of type 2 diabetes mellitus (T2DM). Genetic susceptibility and oxidative stress may play a role in the appearance of T2DM and diabetic neuropathy. We investigated the relation between polymorphism in genes related to oxidative stress such as GSTM1, GSTT1, and GSTP1 and the presence of T2DM and diabetic neuropathy (DN).

METHODS

Samples were collected from 84 patients with T2DM (42 patients with DN and 42 patients without DN) and 98 healthy controls and genotyped by using polymerase chain reaction and restriction fragment length polymorphism method.

RESULTS

GSTP1 Ile105Val polymorphism was associated with the risk of developing T2DM (p = 0.05) but not with the risk of developing DN in diabetic cases. GSTM1 and GSTT1 gene polymorphisms were associated with neither the risk of developing T2DM nor the risk of DN occurrence in diabetic patients. No association was observed between the patients with T2DM and DSPN (diabetic sensorimotor peripheral neuropathy) and T2DM without DSPN regarding investigated polymorphism.

CONCLUSION

Our data suggest that GSTP1 gene polymorphisms may contribute to the development of T2DM in Romanian population. GSTM1, GSTT1, and GSTP1 gene polymorphisms are not associated with susceptibility of developing diabetic neuropathy in T2DM patients.

Fifty-Five Years of Pediatric Endocrinology and 50 Years of the Department of Pediatric Endocrinology, Diabetes and Metabolic Diseases in Slovenia

Paediatric endocrinology started its independent development early in the general development of this specialty, with a strong focus on research and clinical excellence. Slovenian paediatric endocrinology was an integral part of the European paediatric endocrinology from its beginnings and a founding member of the first ‘International Study Group for Diabetes in Children and Adolescents’. After the pioneering work of Prof. Lev Matajc, Prof. Ciril Kržišnik firmly integrated the Department of Pediatric Endocrinology, Diabetes and Metabolic Diseases at the University Children’s Hospital in Ljubljana in the international scientific community. In the last decade, the department participates in cutting-edge research and provides clinical services at highest international standards.

Type 1 Diabetes in the Young: Organization of Two National Centers in Israel and Slovenia

Type 1 diabetes is a chronic autoimmune disease that affects mainly young people. In the last 50 years, a steady increase of the T1D incidence in the young is reported worldwide, with an average 4 % increase annually. In addition, the mean age at the diagnosis is decreasing. Studies show that good metabolic control is important not only for delaying the chronic complications of diabetes but also for improving the quality of life of patients and their families. Continuous education, together with modern technology, is crucial in achieving these goals. Longitudinal data on glycated hemoglobin (HbA1c), along with the data on severe hypoglycemia and severe diabetic ketoacidosis, can describe the quality of care in a defined population. Two national reference diabetes centres taking care of children, adolescents and young adults with diabetes in Israel and Slovenia are described.

Association of Average Telomere Length with Body-Mass Index and Vitamin D Status in Juvenile Population with Type 1 Diabetes

Background

Type 1 diabetes (T1D) is an autoimmune chronic disease where hyperglycemia, increased risk of oxidative stress, advanced glycation end-products and other genetic and environmental factors lead to T1D complications. Shorter telomeres are associated with hyperglycemic levels and lower serum vitamin D levels.

Methods

Average telomere length (ATL) in whole blood DNA samples was assessed with qPCR method in 53 Slovenian T1D children/adolescents (median age 8.7 years, 1:1.3 male/female ratio). Body mass index standard deviation score (BMI-SDS), glycated haemoglobin and serum level of vitamin D metabolite (25-(OH)-D3) and the age at the onset of T1D were collected from the available medical documentation.

Results

Results indicate shorter ATL in subjects with higher BMI-SDS when compared to those with longer ATL (0.455 ± 0.438, −0.63 ± 0.295; p=0.049). Subjects with higher BMI-SDS had lower serum vitamin D levels when compared to those with lower BMI-SDS (40.66 ± 3.07 vs. 52.86 ± 4.85 nmol/L; p=0.045). Vitamin D serum levels did not significantly differ between subjects with longer/shorter ATL.

Conclusion

T1D children/adolescents with shorter ATL tend to have higher BMI-SDS. Lower serum vitamin D levels were associated with higher BMI-SDS, while associations between vitamin D serum levels, age at the onset of T1D, glycated haemoglobin and ATL were not observed. Additional studies with more participants are required to clarify the role of the telomere dynamics in T1D aetiology and development of complications.

GSTM1 and GSTT1 null genotype and diabetic retinopathy: a meta-analysis

Glutathione S-transferases (GSTs) have proved to be involved in the detoxifying several oxidants and may play an important role in diabetic retinopathy (DR). Previous studies on the association between glutathione S-transferase T1 (GSTT1) and GSTM1 polymorphism and DR risk reported inconclusive results. To clarify the possible association, we conducted a meta-analysis of eligible studies. We searched in the PubMed, Embase, and Wangfang Medicine databases for studies assessing the association between GSTM1 and GSTT1 null genotype and DR risk. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association between GSTM1 and GSTT1 null genotype and DR risk. Five studies with 3563 subjects were included in this meta-analysis. The null genotypes of GSTT1 and GSTM1 were associated with a significantly increased risk of DR (OR = 1.69; 95% CI, 1.33-2.16; OR = 1.59; 95% CI, 1.22-2.06), respectively. When stratified by the type of DM, a significantly elevated DR risk was observed in T2DM patients. In conclusion, this meta-analysis suggested that an increased risk of DR was associated with the null polymorphism of GSTT1 and GSTT1, respectively.

Association investigation of BACH2 rs3757247 and SOD2 rs4880 polymorphisms with the type 1 diabetes and diabetes long-term complications risk in the Polish population

Genetic factors are indicated in the development of type 1 diabetes (DM1). Recently, nucleotide variants of BACH2 and SOD2 have been associated with this chronic condition. Therefore, the purpose of the present study was to investigate the contribution of BACH2 rs3757247 and SOD2 rs4880 (Ala16Val) polymorphisms to the risk of DM1 and diabetes long-term complications. Selected polymorphic variants of BACH2 and SOD2 were investigated in a group of 141 patients with DM1 and in a group of age, gender-matched healthy subjects (n=369) using a high-resolution melting curve method. There was no evidence for either allelic or genotypic association with the risk of DM1 and diabetes chronic complications for analysed polymorphisms. In addition, no interaction between BACH2 and SOD2 variants in the development of this condition was observed. However, the frequency of BACH2 rs3757247 AG and AA genotypes was statistically different between DM1 patients with retinopathy and healthy individuals (odds ratio, 2.455; 95% confidence interval, 0.999-6.035; P=0.044), but this result did not survive multiple testing corrections. The present study did not confirm the involvement of BACH2 rs3757247 and SOD2 rs4880 polymorphisms in the development of DM1 and diabetes long-term complications. Further studies in a larger population sample are required.

Manganese superoxide dismutase and oxidative stress modulation

Oxidative stress is characterized by imbalanced reactive oxygen species (ROS) production and antioxidant defenses. Two main antioxidant systems exist. The nonenzymatic system relies on molecules to directly quench ROS and the enzymatic system is composed of specific enzymes that detoxify ROS. Among the latter, the superoxide dismutase (SOD) family is important in oxidative stress modulation. Of these, manganese-dependent SOD (MnSOD) plays a major role due to its mitochondrial location, i.e., the main site of superoxide (O(2)(·-)) production. As such, extensive research has focused on its capacity to modulate oxidative stress. Early data demonstrated the relevance of MnSOD as an O(2)(·-) scavenger. More recent research has, however, identified a prominent role for MnSOD in carcinogenesis. In addition, SOD downregulation appears associated with health risk in heart and brain. A single nucleotide polymorphism which alters the mitochondria signaling sequence for the cytosolic MnSOD form has been identified. Transport into the mitochondria was differentially affected by allelic presence and a new chapter in MnSOD research thus begun. As a result, an ever-increasing number of diseases appear associated with this allelic variation including metabolic and cardiovascular disease. Although diet and exercise upregulate MnSOD, the relationship between environmental and genetic factors remains unclear.

Neurocognitive outcomes in pediatric diabetes: a developmental perspective

The impact of diabetes on the developing brain is well-accepted. Effects on neurocognitive functioning are moderate but have larger functional implications, especially when considered through a developmental lens. Pathophysiological factors such as severe hypoglycemia and chronic hyperglycemia can alter developmental trajectories in early childhood and perhaps at later periods. In this paper, we selectively review neurocognitive outcomes in pediatric diabetes (largely type 1), integrating recent research from developmental neuroscience and neuroimaging. We examine the effects of diabetes at different stages and place findings within a neurodevelopmental diathesis/stress framework. Early-onset diabetes is associated with specific effects on memory and more global cognitive late-effects, but less is known about cognitive outcomes of diabetes in later childhood and in adolescence, a time of increased neurobehavioral vulnerability that has received relatively limited empirical attention. Studies are also needed to better elucidate risk and protective factors that may moderate neurodevelopmental outcomes in youth with diabetes.

The MnSOD Ala16Val SNP: relevance to human diseases and interaction with environmental factors

The relevance of reactive oxygen species (ROS) production relies on the dual role shown by these molecules in aerobes. ROS are known to modulate several physiological phenomena, such as immune response and cell growth and differentiation; on the other hand, uncontrolled ROS production may cause important tissue and cell damage, such as deoxyribonucleic acid oxidation, lipid peroxidation, and protein carbonylation. The manganese superoxide dismutase (MnSOD) antioxidant enzyme affords the major defense against ROS within the mitochondria, which is considered the main ROS production locus in aerobes. Structural and/or functional single nucleotide polymorphisms (SNP) within the MnSOD encoding gene may be relevant for ROS detoxification. Specifically, the MnSOD Ala16Val SNP has been shown to alter the enzyme localization and mitochondrial transportation, affecting the redox status balance. Oxidative stress may contribute to the development of type 2 diabetes, cardiovascular diseases, various inflammatory conditions, or cancer. The Ala16Val MnSOD SNP has been associated with these and other chronic diseases; however, inconsistent findings between studies have made difficult drawing definitive conclusions. Environmental factors, such as dietary antioxidant intake and exercise have been shown to affect ROS metabolism through antioxidant enzyme regulation and may contribute to explain inconsistencies in the literature. Nevertheless, whether environmental factors may be associated to the Ala16Val genotypes in human diseases still needs to be clarified.

Manganese superoxide dismutase (SOD2) polymorphisms, plasma advanced oxidation protein products (AOPP) concentration and risk of kidney complications in subjects with type 1 diabetes

Aims

Oxidative stress is involved in the pathophysiology of diabetic nephropathy. Manganese superoxide dismutase (SOD2) catalyses the dismutation of superoxide, regulates the metabolism of reactive oxygen species in the mitochondria and is highly expressed in the kidney. Plasma concentration of advanced oxidation protein products (AOPP), a marker of oxidative stress, was found to be increased in patients with kidney disease. We investigated associations of SOD2 allelic variations, plasma SOD activity and AOPP concentration with diabetic nephropathy in type 1 diabetic subjects.

Methods

Eight SNPs in the SOD2 region were analysed in 1285 Caucasian subjects with type 1 diabetes from the SURGENE prospective study (n = 340; 10-year follow-up), GENESIS (n = 501) and GENEDIAB (n = 444) cross-sectional studies. Baseline plasma concentration of AOPP and SOD activity were measured in GENEDIAB participants. Hazard ratio (HR) and odds ratio (OR) were determined for incidence and prevalence of nephropathy. Analyses were adjusted or stratified by retinopathy stages.

Results

In the SURGENE cohort, the T-allele of rs4880 (V16A) was associated with the incidence of renal events (new cases, or the progression to a more severe stage of nephropathy; HR 1.99, 95% CI 1.24–3.12, p = 0.004) and with the decline in estimated glomerular filtration rate (eGFR) during follow-up. Similar associations were observed for rs2758329 and rs8031. Associations were replicated in GENESIS/GENEDIAB cohorts, in the subset of participants without proliferative retinopathy, and were confirmed by haplotype analyses. Risk allele and haplotype were also associated with higher plasma AOPP concentration and lower SOD activity.

Conclusions

SOD2 allelic variations were associated with the incidence and the progression of diabetic nephropathy, with a faster decline in eGFR and with plasma AOPP concentration and SOD activity in subjects with type 1 diabetes. These results are consistent with a role for SOD2 in the protection against oxidative stress and kidney disease in type 1 diabetes.

Genetic polymorphisms of glutathione-s-transferase M1 and T1 genes with risk of diabetic retinopathy in Iranian population

OBJECTIVES

To the best of our knowledge, this is the first report on the contributions of GST genetic variants to the risk of diabetic retinopathy in an Iranian population. Therefore, the objective of this study was to determine whether sequence variation in glutathione S-transferase gene (GSTM1 and GSTT1) is associated with development of diabetic retinopathy in type 2 diabetes mellitus (T2DM) Iranian patients.

MATERIALS AND METHODS

A total of 605 subjects were investigated in this case-control study; Study groups consisted of 201 patients with diabetic retinopathy (DR), 203 subjects with no clinically significant signs of DR and a group of 201 cases of healthy volunteers with no clinical evidence of diabetes mellitus or any other diseases. The GSTM1 and GSTT1 were genotyped by multiplex-polymerase chain reaction (multiplex-PCR) analysis in all 404 T2DM patients and 201 healthy individuals served as control.

RESULTS

Increased odds ratio showed that GSTM1-null genotype had a moderately higher occurrence in T2DM patients (OR=1.43, 95% CI=1.01-2.04; P=0.03) than in healthy individuals. However, the frequency of GSTT1 genotype (OR=1.41; 95% CI=0.92-2.18; P=0.09) was not significantly different comparing both groups. Although, regression analysis in T2DM patients showed that GSTM1 and GSTT1 genotypes are not associated with T2DM retinopathy development.

CONCLUSION

Our findings suggest that GSTM1 and GSTT1 genotypes might not be involved in the pathogenesis of type 2 diabetes mellitus retinopathy in the Southern Iranian population. However, further investigations are needed to confirm these results in other larger populations.

Review of Genetic Association in the SOD2 Gene with Chronic Kidney Disease: Case-Control Studies and Meta-Analysis Confirm Association with Diabetic Nephropathy

The SOD2 gene encodes a mitochondrial protein that is involved with response to oxidative stress and cellular proliferation. The diabetic milieu, in particular hyperglycemia, results in the overproduction of superoxide and formation of secondary reactive oxygen species contributing to the accumulation of DNA, protein and cellular damage. Functional genetic variants within the SOD2 gene are postulated to influence renal injury. We sought to resolve the inconsistent conclusions of several studies examining the SOD2 gene for association with chronic kidney disease, in particular diabetic nephropathy. We genotyped a total of 3,913 individuals with diabetic nephropathy, glomerulonephritis and/or end-stage renal disease, reviewed published literature, and conducted a subsequent meta-analysis. Using χ2 test, our independent case-control study for diabetic nephropathy revealed evidence for association of rs4880 (P=0.01). However, this was ameliorated by adjusting for age at diagnosis, duration, sex and recruitment centre in the logistical model. Genotype counts were obtained for all published studies having genotyped this SNP and a meta-analysis was performed on a total of 3,949 individuals with type 1 diabetes mellitus (cases n=2,184; controls, n=1,765). No significant heterogeneity was observed (P=0.5) and association with diabetic nephropathy was supported by P=0.005 (odds ratio 0.87, 95% confidence interval: 0.79–0.96). There is biological evidence that this amino-acid changing SNP, rs4880, directly influences enzymatic activity of the SOD2 gene product. We conclude that the functional, clinically associated rs4880 is important in the pathogenesis of diabetic nephropathy.

Rare single nucleotide polymorphisms in the regulatory regions of the superoxide dismutase genes in autism spectrum disorder

Oxidative stress is suspected to be one of the several contributing factors in the etiology of autism spectrum disorder (ASD). We analyzed genes of the superoxide dismutase family (SOD1, SOD2, and SOD3) that are part of a major antioxidative stress system in human in order to detect the genetic variants contributing to the development of ASD. Using the optimized high-resolution melting (HRM) analysis, we identified two rare single nucleotide polymorphisms (SNPs) associated with the etiology of ASD. Both are located in the superoxide dismutase 1 (SOD1) gene and have a minor allele frequency in healthy population ~5%. The SNP c.239 + 34A>C (rs2234694) and SNP g.3341C>G (rs36233090) were detected with an odds ratio of 2.65 and P < 0.01. Both are located in the noncoding potentially regulatory regions of the SOD1 gene. This adds to the importance of rare SNPs in the etiology of complex diseases as well as to the importance of noncoding genetic variants analysis with a potential influence on the regulation of gene expression.

Manganese supplementation protects against diet-induced diabetes in wild type mice by enhancing insulin secretion

Mitochondrial dysfunction is both a contributing mechanism and complication of diabetes, and oxidative stress contributes to that dysfunction. Mitochondrial manganese-superoxide dismutase (MnSOD) is a metalloenzyme that provides antioxidant protection. We have previously shown in a mouse model of hereditary iron overload that cytosolic iron levels affected mitochondrial manganese availability, MnSOD activity, and insulin secretion. We therefore sought to determine the metallation status of MnSOD in wild-type mice and whether altering that status affected β-cell function. 129/SvEVTac mice given supplemental manganese exhibited a 73% increase in hepatic MnSOD activity and increased metallation of MnSOD. To determine whether manganese supplementation offered glucose homeostasis under a situation of β-cell stress, we challenged C57BL/6J mice, which are more susceptible to diet-induced diabetes, with a high-fat diet for 12 weeks. Manganese was supplemented or not for the final 8 weeks on that diet, after which we examined glucose tolerance and the function of isolated islets. Liver mitochondria from manganese-injected C57BL/6J mice had similar increases in MnSOD activity (81%) and metallation as were seen in 129/SvEVTac mice. The manganese-treated group fed high fat had improved glucose tolerance (24% decrease in fasting glucose and 41% decrease in area under the glucose curve), comparable with mice on normal chow and increased serum insulin levels. Isolated islets from the manganese-treated group exhibited improved insulin secretion, decreased lipid peroxidation, and improved mitochondrial function. In conclusion, MnSOD metallation and activity can be augmented with manganese supplementation in normal mice on normal chow, and manganese treatment can increase insulin secretion to improve glucose tolerance under conditions of dietary stress.

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.

The association between glutathione S-transferase T1 and M1 gene polymorphisms and cardiovascular autonomic neuropathy in Slovak adolescents with type 1 diabetes mellitus

Glutathione S-transferase (GST), as antioxidant enzyme, protects tissue from oxidative damage typical for many pathologic conditions as type 1 diabetes (T1D) and its chronic complications. The aim of the study was to compare the prevalence of GST T1/M1 gene polymorphisms between diabetic adolescents with (CAN+) and without (CAN-) cardiovascular autonomic neuropathy. Forty-six subjects with T1D at the age 15-19 years were enrolled. CAN was diagnosed in 19 patients (41.3%) based on standard cardiovascular tests. GST M1 null genotype was more prevalent in CAN+subjects but this was not statistically significant (OR=1.889, 0.61-6.55, p>0.05). GST T1 wild genotype nearly 5-fold increased the risk of CAN (OR=4.952, 1.13-21.739, p<0.05). Regarding genotype combination, GST T1/M1 wild/null genotype was significantly more frequent in CAN+compared to the CAN- subjects (OR=3.96, 1.024-15.302, p<0.05). No significant difference was found in any biochemical parameters between CAN+and CAN- subgroups. Multivariable logistic regression showed that none of the biochemical parameters estimated was considered a risk factor for CAN, however GST T1 wild and GST T1/M1 wild/null represented a risk factor for CAN development (OR=2.227, 1.079-4.587, p<0.05 and OR=1.990, 1.026-3.859, p<0.05, respectively). GST T1 wild allele and GST T1/M1 wild/null genotype can be considered as risk factors for CAN in Slovak adolescents with T1D.

Evaluation of oxidative stress markers in pathogenesis of diabetic neuropathy

Experimental evidences suggest that hyperglycaemia-induced overproduction of reactive oxygen species and subsequent damage to proteins, lipids and DNA may play a key role in the development of distal symmetric polyneuropathy (DSPN)—the most common complication of diabetes mellitus. The study population consisted of 51 individuals aged 52–82 years classified into 3 groups: 16 patients diagnosed with type 2 diabetes mellitus (T2DM) with DSPN, 16 T2DM patients without DSPN and 19 control subjects without diabetes and neuropathy. The study was conducted to determine the activity of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX) and total antioxidant status (TAS) in the examined groups. An alkaline comet assay was used to determine the extent of DNA damage of oxidized purines as glicosylo-formamidoglicosylase (Fpg) sites, and oxidized pyrimidines as endonuclease III (Nth) sites. A significant decrease of SOD (P < 0.05), GPX (P < 0.05) and nonsignificant decrease of CAT (P > 0.05), and TAS status (P > 0.05) were seen in T2DM patients with neuropathy compared to T2DM patients as well as controls. T2DM patients with or without neuropathy revealed significantly lower (P < 0.05) plasma concentration of nitrous oxide compared to the control subjects. Endogenous level of oxidative DNA damage in T2DM patients with DSPN was significantly higher compared both to the controls and T2DM patients without DSPN (P < 0.001). Moreover, lymphocytes isolated from T2DM patients with DSPN were more susceptible to oxidative DNA lesions induced by hydrogen peroxide than from T2DM patients without DSPN (P < 0.001). Our results confirm hypothesis that oxidative stress may play a substantial role in the development and progression of diabetic distal symmetric polyneuropathy.

Inducible nitric oxide synthase genetic polymorphism and risk of asbestosis

Asbestos, a known occupational pollutant, may upregulate the activity of inducible nitric oxide synthase (iNOS) and thus the production of nitric oxide (NO). This study investigated whether iNOS (CCTTT)_n polymorphism is associated with an increased asbestosis risk in exposed workers. The study cohort consisted of 262 cases with asbestosis and 265 controls with no asbestos-related disease. For each subject the cumulative asbestos exposure data were available. The number of CCTTT repeats was determined following PCR amplification of the iNOS promoter region. Logistic regression was performed to estimate asbestosis risk. The OR of asbestosis was 1.20 (95%  CI = 0.85–1.69) for the LL genotype compared to the combined SL and SS genotypes and 1.26 (95% CI = 0.86–1.85) for the LL genotype compared to the SL genotype. The results of this study are borderline significant and suggest a possible role of iNOS (CCTTT)_n polymorphism in the risk of asbestosis; however, further studies are needed.

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.

Diabetic retinopathy, superoxide damage and antioxidants

Retinopathy, the leading cause of acquired blindness in young adults, is one of the most feared complications of diabetes, and hyperglycemia is considered as the major trigger for its development. The microvasculature of the retina is constantly bombarded by high glucose, and this insult results in many metabolic, structural and functional changes. Retinal mitochondria become dysfunctional, its DNA is damaged and proteins encoded by its DNA are decreased. The electron transport chain system becomes compromised, further producing superoxide and providing no relief to the retina from a continuous cycle of damage. Although the retina attempts to initiate repair mechanisms by inducing gene expressions of the repair enzymes, their mitochondrial accumulation remains deficient. Understanding the molecular mechanism of mitochondrial damage should help identify therapies to treat/retard this sight threatening complication of diabetes. Our hope is that if the retinal mitochondria are maintained healthy with adjunct therapies, the development and progression of diabetic retinopathy can be inhibited.

Prediction of diabetic retinopathy: role of oxidative stress and relevance of apoptotic biomarkers

Diabetic retinopathy (DR) is the foremost cause of blindness in working-aged worldwide; it is characterized by vascular and neuronal degeneration. Features of DR include leukocyte adhesion, increased vascular permeability, neovascularization and neuronal cell death. Early diagnosis and intervention are important to prevent or at least ameliorate the development of DR. Recent reports indicate that pathophysiological mechanisms leading to diabetic retinopathy include oxidative stress and retinal cell death cascades. Circulating biomarkers of oxidative stress such as malondialdehyde (MDA), thiobarbituric acid reacting substances (TBARS), conjugated diene (CD), advanced oxidation protein products (AOPP), protein carbonyl, 8-hydroxydeoxyguanosin (8-OHdG), nitrotyrosine, and F(2) isoprostanes and pro-apoptosis molecules (caspase-3, Fas, and Bax) are associated with increased susceptibility to develop DR in diabetic subjects. Thus, identification of oxidative stress and cell death biomarkers in diabetic patients could be in favor of predicting, diagnosis, and prevention of DR, and to target for novel therapeutic interventions.