Association of Nrf2, SOD2 and GPX1 Polymorphisms with Biomarkers of Oxidative Distress and Survival in End-Stage Renal Disease Patients

Comparison of the nephroprotective effect of [6]-gingerol and the [6]-gingerol-β-cyclodextrin complex against cisplatin-induced AKI

Cisplatin is an antineoplastic agent effective for the treatment of several cancers. However, due to its nephrotoxicity, its use is limited. Acute kidney injury (AKI) induced by cisplatin is caused by inflammation, apoptosis, and oxidative stress in renal tubular cells. Natural compounds derived from ginger (Zingiber officinale) such as [6]-gingerol, possess anti-inflammatory and antioxidant properties. This study explores the protective effects of [6]-gingerol and its β-cyclodextrin complex ([6]-gingerol-β-CD) on cisplatin-induced AKI in mice. We hypothesize that complexing [6]-gingerol with β-cyclodextrin would enhance its solubility and reduce its pungency, making it more suitable for clinical use. Additionally, we aim to determine whether β-cyclodextrin complexation can improve the oral bioavailability of [6]-gingerol without compromising its therapeutic efficacy. The minimum dose of cisplatin required to induce AKI was determined to be 15 mg/kg. Female Swiss mice (n = 6-8) were divided into four groups: control, cisplatin (15 mg/kg), [6]-gingerol (12.5 mg/kg), and [6]-gingerol-β-CD (12.5 mg/kg). The treatments were administered orally for 5 days. On the third day, cisplatin was administered intraperitoneally (i.p.), and the animals were euthanized after 5 days. All biochemical parameters investigated, such as plasma urea and creatinine, urinary gamma GT, urinary protein, MPO, and GSH were altered by cisplatin. The parameters evaluated in this study were categorized into renal function, inflammation, and oxidative stress. Both [6]-gingerol and complexed gingerol effectively restored most of the evaluated parameters to control levels. Following these analyses, we investigated the JAK/STAT pathway and observed that gingerol deactivates this pathway, thereby preventing cisplatin-induced nephrotoxicity. In conclusion, β-CD complexation did not interfere with [6]-gingerol therapeutic, emphasizing its indication for future clinical tests. Further analysis showed that [6]-gingerol prevented cisplatin nephrotoxicity by deactivating JAK/STAT signaling pathway.

Association of acute exposure to PM2.5 constituents and sources with kidney injury: A longitudinal panel study of Nrf2 promoter polymorphism

Evidence on the effects of fine particulate matter (PM2.5) constituents and sources on kidney injury is limited. We designed a panel study with 4 repeated measurements to investigate the association of acute exposure to chemical constituents and source-specific PM2.5 with kidney function and renal tubular injury. We further evaluated the modifying effect of Nrf2 promoter polymorphism. In this study, a total of 64 participants were recruited and ambient PM2.5 constituents were monitored at a fixed-site station. We used a positive matrix factorization (PMF) model to identify emission sources and linear mixed-effect models to explore the associations. An interquartile range (IQR) increase in PM2.5 concentration was associated with a 1.40 % and 3.15 % decrease in eGFR-Cr (eGFR assessed by creatinine) and eGFR-Cys (eGFR assessed by cystatin-C), respectively, and 10.2 % higher kidney injury molecule 1 (KIM-1) levels. Carbonaceous components (EC and OC), metallic elements (Cr, K, Pb, Zn) and Cl- were robustly responsible for kidney injury. Per IQR increase in these constituents accounted for 0.57 % to 1.62 % declines in eGFR-Cr; 1.36 % to 3.66 % declines in eGFR-Cys; and 7.50 % to 19.83 % increments in KIM-1. Specific source analysis revealed that PM2.5 emitted by combustion was associated with the largest reduction in eGFR, while the secondary source played a more prominent role in renal tubular injury. The dominant models showed that the magnitudes of the effect estimates of PM2.5 and its constituents were generally larger in the participants with minor alleles of the Nrf2 promoter. These findings suggest that acute exposure to EC, OC, Cl- and several metallic constituents may be responsible for kidney injury induced by PM2.5, especially in individuals with unfavorable Nrf2 genotypes. PM2.5 from combustion and secondary sources impairs kidney health, highlighting the importance of source-oriented PM2.5 control strategies.

Association of MnSOD, CAT, and GPx1 Gene Polymorphism with Risk of Diabetic Nephropathy in South Indian Patients: A Case-Control Study

Diabetic nephropathy (DN) is one of the common complications of type 2 diabetes mellitus (T2DM), and oxidative stress plays a key role in the pathogenesis of DN. Studies have demonstrated that antioxidants (MnSOD, CAT, and GPx1) may reduce the complications associated with T2DM. The purpose of the study is to correlate the role of antioxidant gene polymorphisms in the pathogenesis of DN among T2DM individuals in the South Indian population. It clarifies the importance of early manifestation and reliable genetic indicators modulating the oxidative stress mechanism in DN. The study participants were divided and grouped as Group 1: Control, Group 2: T2DM without DN, and Group 3: T2DM with DN (n = 100 in each group). The levels of plasma glucose, HbA1c, renal profile, SOD, CAT, GPx1, MDA, and TAS were assessed. MnSOD (rs4880), CAT (rs1049982), and GPx1 (rs1050450) polymorphisms were genotyped via Tetra-arms PCR. The genotypes of GPx1 depict a significant role in the progression of DN in T2DM patients (co-dominant [OR: 2.134; 95% CI (1.202-3.788), p < 0.01], dominant [OR: 2.015; 95% CI (1.117-3.634), p = 0.02], and recessive model [OR: 2.215; 95% CI (1.235-3.972), p = 0.008]); whereas rs4880 and rs1049982 polymorphisms are not associated with DN progression. As a result, GPx1 (rs1050450) polymorphism could be a diagnostic risk factor for developing DN in T2DM patients. Moreover, the genotypes of rs4880 and rs1049982 polymorphism show significant difference in the antioxidant parameters compared to the genotypes of rs1050450. In contradiction to earlier studies, the current study demonstrates that the genotypes of rs1050450 (GPx1) can be considered as an influential component for higher susceptibility and risk of developing DN in T2DM patients among the South Indian population.

The role of Nrf2 in immune cells and inflammatory autoimmune diseases: a comprehensive review

INTRODUCTION

Nrf2 regulates mild stress, chronic inflammation, and metabolic changes by regulating different immune cells via downstream signaling. Collection of information about the role of Nrf2 in inflammatory autoimmune diseases will better understand the therapeutic potential of targeting Nrf2 in these diseases.

AREAS COVERED

In this review, we comprehensively discussed biological function of Nrf2 in different immune cells, including Nrf2 preventing oxidative tissue injury, affecting apoptosis of immune cells and inflammatory cytokine production. Moreover, we discussed the role of Nrf2 in the development of inflammatory autoimmune diseases.

EXPERT OPINION

Nrf2 binds to downstream signaling molecules and then provides durable protection against different cellular and organ stress. It has emerged as an important target for inflammatory autoimmune diseases. Development of Nrf2 modulator drugs needs to consider factors such as target specificity, short/long term safety, disease indication identification, and the extent of variation in Nrf2 activity. We carefully discussed the dual role of Nrf2 in some diseases, which helps to better target Nrf2 in the future.

Guideline directed medical therapy induced nephrotoxicity in HFrEF patients; an insight to its mechanism

Guideline Directed Medical Therapy (GDMT) has been the standard pharmacotherapy for the treatment of Heart Failure patients with reduced Ejection Fraction (HFrEF) recommended by the European Society of Cardiology (ESC). However, patients on GDMT are likely to possess nephrotoxicity as an adverse effect. We utilized multiple system biology tools like ADVER-Pred, gene enrichment analysis, molecular docking, molecular dynamic simulations, and MMPBSA analysis to predict a possible molecular mechanism of how selected combinations of GDMT may cause nephrotoxicity. As per the ACC/AHA/ESC guidelines, we categorized the drugs as category 1 including β-blockers (BB), angiotensin receptor blockers (ARB), and sodium-glucose cotransporter-2 inhibitors (SGLT2I), category 2 includes BB's, SGLT2I, and angiotensin receptor-neprilysin inhibitors (ARNI), and category 3 includes BB's, SGLT2I, and angiotensin-converting enzyme (ACE) inhibitors. Enrichment analysis predicted category 2 drugs to possess the highest number of proteins to be involved in the development of nephrotoxicity i.e. 79.41%. The targets HBA1, CBR1, ATG5, and SLC6A3 were the top hub genes with an edge count of 7 followed by GPX1 with an edge count of 6. Molecular docking studies revealed candesartan-SLC6A3 to possess the highest binding affinity of -10.2 kcal/mol. In addition, simulation studies displayed empagliflozin-CBR1 to possess the highest stability followed by candesartan-ATG5. A combination of β-blockers, ARBs, and SGLT2I are predicted to likely possess nephrotoxicity which may be due to the modulation of HBA1, CBR1, ATG5, and GPX1. In conclusion, candesartan and empagliflozin are most likely to cause nephrotoxicity via the modulation of HBA1, CBR1, ATG5, and GPX1.Communicated by Ramaswamy H. Sarma.

Effects of NRF2 polymorphisms on safety and efficacy of bardoxolone methyl: subanalysis of TSUBAKI study

BACKGROUND

In the TSUBAKI study, bardoxolone methyl significantly increased measured and estimated glomerular filtration rates (GFR) in patients with multiple forms of chronic kidney disease (CKD), including Japanese patients with type 2 diabetes and stage 3-4 CKD. Since bardoxolone methyl targets the nuclear factor erythroid 2-related factor 2 pathway, this exploratory analysis of the TSUBAKI study investigated the impact of the regulatory single nucleotide polymorphism, rs6721961, on the effects of bardoxolone methyl.

METHODS

Japanese patients aged 20-79 years with type 2 diabetes and stage 3-4 CKD were randomized to bardoxolone methyl 5-15 mg/day (titrated as tolerated) or placebo for 16 weeks. Genotype frequency, clinical characteristics, renal function, and adverse events were primarily assessed.

RESULTS

Of 104 patients (bardoxolone methyl n = 55, placebo n = 49); 57% were genotype C/C, 32% C/A and 12% A/A. The frequency of the A/A genotype was higher among patients with diabetic kidney disease than in the general Japanese population (~ 5%). Measured and estimated GFRs increased from baseline in all genotypes receiving bardoxolone methyl. There were no significant differences between genotypes for safety parameters, including blood pressure, bodyweight, and levels of B-type natriuretic peptide, or in the type and frequency of adverse events, suggesting that the efficacy and safety of bardoxolone methyl are unaffected by the rs6721961 polymorphism-617 (C→A) genotype.

CONCLUSIONS

Our approach of combining genome analysis with clinical trials for an investigational drug provides important and useful clues for exploring the efficacy and safety of the drug.

TRIAL REGISTRATION

ClinicalTrials.gov; NCT02316821.

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.

GPX3 rs8177412 Polymorphism Modifies Risk of Upper Urothelial Tumors in Patients with Balkan Endemic Nephropathy

Current data suggest that aristolochic acid (AA) exposure is a putative cause of Balkan endemic nephropathy (BEN), a chronic kidney disease strongly associated with upper tract urothelial carcinoma. The cellular metabolism of AA is associated with the production of reactive oxygen species, resulting in oxidative distress. Purpose: Therefore, the aim of this study was to analyze individual, combined and cumulative effect of antioxidant gene polymorphisms (Nrf2 rs6721961, KEAP1 rs1048290, GSTP1AB rs1695, GSTP1CD rs1138272, GPX3 rs8177412 and MDR1 rs1045642), as well as GSTP1ABCD haplotypes with the risk for BEN development and associated urothelial cell carcinoma in 209 BEN patients and 140 controls from endemic areas. Experimental method: Genotyping was performed using polymerase chain reaction (PCR) and PCR with confronting two-pair primers (PCR-CTTP) methods. Results: We found that female patients carrying both variant GPX3 rs8177412 and MDR1 rs1045642 genotypes in combination exhibited significant risk towards BEN (OR 1 = 3.34, 95% CI = 1.16-9.60, p = 0.025; OR 2 = 3.79, 95% CI = 1.27-11.24, p = 0.016). Moreover, significant association was determined between GPX3rs8174412 polymorphism and risk for urothelial carcinoma. Carriers of variant GPX3*TC + CC genotype were at eight-fold increased risk of BEN-associated urothelial tumors development. There was no individual or combined impact on BEN development and BEN-associated tumors among all examined polymorphisms. The haplotype consisting of variant alleles for both polymorphisms G and T was associated with 1.6-fold increased risk although statistically insignificant (OR = 1.64; 95% CI = 0.75-3.58; p = 0.21). Conclusions: Regarding GPX3 rs8177412 polymorphism, the gene variant that confers lower expression is associated with significant increase in upper urothelial carcinoma risk. Therefore, BEN patients carrying variant GPX3 genotype should be more frequently monitored for possible upper tract urothelial carcinoma development.

Omics biomarkers and an approach for their practical implementation to delineate health status for personalized nutrition strategies

Personalized nutrition (PN) has gained much attention as a tool for empowerment of consumers to promote changes in dietary behavior, optimizing health status and preventing diet related diseases. Generalized implementation of PN faces different obstacles, one of the most relevant being metabolic characterization of the individual. Although omics technologies allow for assessment the dynamics of metabolism with unprecedented detail, its translatability as affordable and simple PN protocols is still difficult due to the complexity of metabolic regulation and to different technical and economical constrains. In this work, we propose a conceptual framework that considers the dysregulation of a few overarching processes, namely Carbohydrate metabolism, lipid metabolism, inflammation, oxidative stress and microbiota-derived metabolites, as the basis of the onset of several non-communicable diseases. These processes can be assessed and characterized by specific sets of proteomic, metabolomic and genetic markers that minimize operational constrains and maximize the information obtained at the individual level. Current machine learning and data analysis methodologies allow the development of algorithms to integrate omics and genetic markers. Reduction of dimensionality of variables facilitates the implementation of omics and genetic information in digital tools. This framework is exemplified by presenting the EU-Funded project PREVENTOMICS as a use case.

Complement component 3 protects human bronchial epithelial cells from cigarette smoke-induced oxidative stress and prevents incessant apoptosis

The complement component 3 (C3) is a pivotal element of the complement system and plays an important role in innate immunity. A previous study showed that intracellular C3 was upregulated in airway epithelial cells (AECs) from individuals with end-stage chronic obstructive pulmonary disease (COPD). Accumulating evidence has shown that cigarette smoke extract (CSE) induces oxidative stress and apoptosis in AECs. Therefore, we investigated whether C3 modulated cigarette smoke-induced oxidative stress and apoptosis in AECs and participated in the pathogenesis of COPD. We found increased C3 expression, together with increased oxidative stress and apoptosis, in a cigarette smoke-induced mouse model of COPD and in AECs from patients with COPD. Different concentrations of CSEinduced C3 expression in 16HBE cells in vitro. Interestingly, C3 knockdown (KD) exacerbated oxidative stress and apoptosis in 16HBE cells exposed to CSE. Furthermore, C3 exerted its pro-survival effects through JNK inhibition, while exogenous C3 partially rescued CSE-induced cell death and oxidative stress in C3 KD cells. These data indicate that locally produced C3 is an important pro-survival molecule in AECs under cigarette smoke exposure, revealing a potentially novel mechanism in the pathogenesis of COPD.

miR-122-5p Regulates Renal Fibrosis In Vivo

The role of exogenous microRNAs (miRNAs) in renal fibrosis is poorly understood. Here, the effect of exogenous miRNAs on renal fibrosis was investigated using a renal fibrosis mouse model generated by unilateral ureteral obstruction (UUO). miRNA microarray analysis and quantitative reverse-transcription polymerase chain reaction showed that miR-122-5p was the most downregulated (0.28-fold) miRNA in the kidneys of UUO mice. The injection of an miR-122-5p mimic promoted renal fibrosis and upregulated COL1A2 and FN1, whereas an miR-122-5p inhibitor suppressed renal fibrosis and downregulated COL1A2 and FN1. The expression levels of fibrosis-related mRNAs, which were predicted targets of miR-122-5p, were evaluated. The expression level of TGFBR2, a pro-fibrotic mRNA, was upregulated by the miR-122-5p mimic, and the expression level of FOXO3, an anti-fibrotic mRNA, was upregulated by the miR-122-5p inhibitor. The protein expressions of TGFBR2 and FOXO3 were confirmed by immunohistochemistry. Additionally, the expression levels of LC3, downstream anti-fibrotic mRNAs of FOXO3, were upregulated by the miR-122-5p inhibitor. These results suggest that miR-122-5p has critical roles in renal fibrosis.

Correlative study on heavy metal-induced oxidative stress and hypertension among the rural population of Malwa Region of Punjab, India

Heavy metal-induced toxicity contributes to the progression of various metabolic disorders and possible mechanisms involved in disease progression are not well established. In this study, the correlation of  heavy metal exposure and  hypertension have been demonstrated. The results showed that in hypertensive subjects, the lipid profiles (triglycerides, LDL-C, HDL-C, and total cholesterol) and cardiac markers (CK-MB and LDH) were altered abruptly. As a consequence of heavy- induced oxidative stress, the oxidants (TBARS and protein carbonyls) and antioxidants (SOD, GSH, and TAC) were significantly increased and decreased, respectively in hypertension subjects. The concentrations of heavy metals (Pb, Cd, and As) exceeded the permissible limits in hypertensive subjects. The Nrf-2 genotyping indicated that heavy metals may induce mutations at molecular level. The results of correlation analysis revealed that the heavy metals interact with cellular components and interfere with metabolic processes which then results in disturbed lipid profile, enhanced oxidative stress, and reduced antioxidant status. The current study systematically estimated the association of hair and nail heavy metal concentrations with hypertension among the population residing in the Malwa region of Punjab. The proposed study highlighted that heavy metals act as a silent risk factor in the hypertension progression in the population of Malwa region. Future studies are required to confirm current findings and further scrutinize the effect of heavy metals exposure in early adulthood, early, and late mid-life to develop metabolic complications such as hypertension.

Oxidative Stress Management in Cardiorenal Diseases: Focus on Novel Antidiabetic Agents, Finerenone, and Melatonin

Oxidative stress is characterized by excessive production of reactive oxygen species together with exhausted antioxidant defenses. This constitutes a main pathophysiologic process that is implicated in cardiovascular and renal diseases. In particular, enhanced oxidative stress may lead to low-density lipoprotein accumulation and oxidation, endothelial cell activation, adhesion molecule overexpression, macrophage activation, and foam cell formation, promoting the development and progression of atherosclerosis. The deleterious kidney effects of oxidative stress are numerous, including podocytopathy, mesangial enlargement, renal hypertrophy, tubulointerstitial fibrosis, and glomerulosclerosis. The prominent role of oxidative mechanisms in cardiorenal diseases may be counteracted by recently developed pharmacotherapies such as novel antidiabetic agents and finerenone. These agents have demonstrated significant antioxidant activity in preclinical and clinical studies. Moreover, the use of melatonin as a treatment in this field has been experimentally investigated, with large-scale clinical studies being awaited. Finally, clinical implications and future directions in this field are presented.

Empowering consumers to PREVENT diet-related diseases through OMICS sciences (PREVENTOMICS): protocol for a parallel double-blinded randomised intervention trial to investigate biomarker-based nutrition plans for weight loss

INTRODUCTION

Personalised nutrition holds immense potential over conventional one-size-fits-all approaches for preventing and treating diet-related diseases, such as obesity. The current study aims to examine whether a personalised nutritional plan produces more favourable health outcomes than a standard approach based on general dietary recommendations in subjects with overweight or obesity and elevated waist circumference.

METHODS AND ANALYSIS

This project is a 10-week parallel, double-blinded randomised intervention trial. We plan to include 100 adults aged 18-65 years interested in losing weight, with body mass index ≥27 but<40 kg/m² and elevated waist circumference (males >94 cm; females >80 cm). Participants will be categorised into one of five predefined 'clusters' based on their individual metabolic biomarker profile and genetic background, and will be randomised in a 1:1 ratio to one of two groups: (1) personalised plan group that will receive cluster-specific meals every day for 6 days a week, in conjunction with a personalised behavioural change programme via electronic push notifications; or (2) control group that will receive meals following the general dietary recommendations in conjunction with generic health behaviour prompts. The primary outcome is the difference between groups (personalised vs control) in the change in fat mass from baseline. Secondary outcomes include changes in weight and body composition, fasting blood glucose and insulin, lipid profile, adipokines, inflammatory biomarkers, and blood pressure. Other outcomes involve measures of physical activity and sleep patterns, health-related quality of life, dietary intake, eating behaviour, and biomarkers of food intake. The effect of the intervention on the primary outcome will be analysed by means of linear mixed models.

ETHICS AND DISSEMINATION

The protocol has been approved by the Ethics Committee of the Capital Region, Copenhagen, Denmark. Study findings will be disseminated through peer-reviewed publications, conference presentations and media outlets.

TRIAL REGISTRATION NUMBER

NCT04590989.

Genetic Variations on Redox Control in Cardiometabolic Diseases: The Role of Nrf2

The transcription factor Nrf2 is a master regulator of multiple cytoprotective genes that maintain redox homeostasis and exert anti-inflammatory functions. The Nrf2-Keap1 signaling pathway is a paramount target of many cardioprotective strategies, because redox homeostasis is essential in cardiovascular health. Nrf2 gene variations, including single nucleotide polymorphisms (SNPs), are correlated with cardiometabolic diseases and drug responses. SNPs of Nrf2, KEAP1, and other related genes can impair the transcriptional activation or the activity of the resulting protein, exerting differential susceptibility to cardiometabolic disease progression and prevalence. Further understanding of the implications of Nrf2 polymorphisms on basic cellular processes involved in cardiometabolic diseases progression and prevalence will be helpful to establish more accurate protective strategies. This review provides insight into the association between the polymorphisms of Nrf2-related genes with cardiometabolic diseases. We also briefly describe that SNPs of Nrf2-related genes are potential modifiers of the pharmacokinetics that contribute to the inter-individual variability.

Genetic Polymorphisms of MnSOD Modify the Impacts of Environmental Melamine on Oxidative Stress and Early Kidney Injury in Calcium Urolithiasis Patients

Environmental melamine exposure increases the risks of oxidative stress and early kidney injury. Manganese superoxide dismutase (MnSOD), glutathione peroxidase, and catalase can protect the kidneys against oxidative stress and maintain normal function. We evaluated whether their single-nucleotide polymorphisms (SNPs) could modify melamine’s effects. A total of 302 patients diagnosed with calcium urolithiasis were enrolled. All patients provided one-spot overnight urine samples to measure their melamine levels, urinary biomarkers of oxidative stress and renal tubular injury. Median values were used to dichotomize levels into high and low. Subjects carrying the T allele of rs4880 and high melamine levels had 3.60 times greater risk of high malondialdehyde levels than those carrying the C allele of rs4880 and low melamine levels after adjustment. Subjects carrying the G allele of rs5746136 and high melamine levels had 1.73 times greater risk of high N-Acetyl-β-d-glucosaminidase levels than those carrying the A allele of rs5746136 and low melamine levels. In conclusion, the SNPs of MnSOD, rs4880 and rs5746136, influence the risk of oxidative stress and renal tubular injury, respectively, in calcium urolithiasis patients. In the context of high urinary melamine levels, their effects on oxidative stress and renal tubular injury were further increased.

The ALA5/ALA6/ALA7 repeat polymorphisms of the glutathione peroxidase-1 (GPx1) gene and autism spectrum disorder

Autism is a severe neurodevelopmental disorder leading to deficits in social interaction, communication, and several activities. An increasing number of evidence suggests a role of oxidative stress in the etiology of autism spectrum disorder (ASD). Indeed, impaired antioxidant mechanisms may lead to the inadequate removal of H₂O₂ with a consequent increase in highly active hydroxyl radicals and other reactive oxygen species causing cellular damages. The GPx1 is one of the most important enzymes counteracting oxidative stress. In this work, we investigated a possible correlation between the GCG repeat polymorphism present in the first exon of GPx1 gene encoding a tract of five to seven alanine residues (ALA5, ALA6, and ALA7) and ASD. Our findings highlighted a high frequency of ALA5 allele in ASD subjects. Moreover, proteins corresponding to the three GPx1 variants were produced in vitro, and the evaluation of their activity showed a lower values for GPx1 having ALA5 polymorphism. The comparison of the secondary and tertiary structure predictions revealed an alpha‐helix in correspondence of alanine stretch only in the case of GPx1‐ALA7 variant. Finally, to better investigate protein structure, steady‐state fluorescence measurements of GPx1 intrinsic tryptophan were carried out and the three tested proteins exhibited a different stability under denaturing conditions. This work demonstrates the importance in adopting a multidisciplinary strategy to comprehend the role of GPx1 in ASD.

Results here obtained suggest a possible role of ALA5 GPx1 variant in ASD. However, given the multifactorial nature of autism, this evidence might be a piece of a more complex puzzle being the GPx1 enzyme part of a complex pathway in which several proteins are involved.

GSTM1 Modulates Expression of Endothelial Adhesion Molecules in Uremic Milieu

Deletion polymorphism of glutathione S-transferase M1 (GSTM1), a phase II detoxification and antioxidant enzyme, increases susceptibility to end-stage renal disease (ESRD) as well as the development of cardiovascular diseases (CVD) among ESRD patients and leads to their shorter cardiovascular survival. The mechanisms by which GSTM1 downregulation contributes to oxidative stress and inflammation in endothelial cells in uremic conditions have not been investigated so far. Therefore, the aim of the present study was to elucidate the effects of GSTM1 knockdown on oxidative stress and expression of a panel of inflammatory markers in human umbilical vein endothelial cells (HUVECs) exposed to uremic serum. Additionally, we aimed to discern whether GSTM1-null genotype is associated with serum levels of adhesion molecules in ESRD patients. HUVECs treated with uremic serum exhibited impaired redox balance characterized by enhanced lipid peroxidation and decreased antioxidant enzyme activities, independently of the GSTM1 knockdown. In response to uremic injury, HUVECs exhibited alteration in the expression of a series of inflammatory cytokines including retinol-binding protein 4 (RBP4), regulated on activation, normal T cell expressed and secreted (RANTES), C-reactive protein (CRP), angiogenin, dickkopf-1 (Dkk-1), and platelet factor 4 (PF4). GSTM1 knockdown in HUVECs showed upregulation of monocyte chemoattractant protein-1 (MCP-1), a cytokine involved in the regulation of monocyte migration and adhesion. These cells also have shown upregulated intracellular and vascular cell adhesion molecules (ICAM-1 and VCAM-1). In accordance with these findings, the levels of serum ICAM-1 and VCAM-1 (sICAM-1 and sVCAM-1) were increased in ESRD patients lacking GSTM1, in comparison with patients with the GSTM1-active genotype. Based on these results, it may be concluded that incubation of endothelial cells in uremic serum induces redox imbalance accompanied with altered expression of a series of cytokines involved in arteriosclerosis and atherosclerosis. The association of GSTM1 downregulation with the altered expression of adhesion molecules might be at least partly responsible for the increased susceptibility of ESRD patients to CVD.

The importance of polymorphisms of regulatory and catalytic antioxidant proteins in chronic kidney disease

Both excessive production of reactive oxygen species (ROS) and impaired antioxidant function are found in patients with chronic kidney disease (CKD). Therefore, individual susceptibility towards CKD can be induced by functional variations of genes encoding antioxidant regulatory (nuclear factor erythroid 2 - related factor 2 (Nrf2)) and catalytic (superoxide dismutase (SOD2) and glutathione peroxidase (GPX1)) proteins. Several types of single nucleotide polymorphisms (SNPs) have been found within the genes encoding these proteins, with Nrf2 (-617C/A), SOD2 (Ala16Val) and GPX1 (Pro198Leu) conferring impaired catalytic activity. The most unexplored gene polymorphism in CKD susceptibility, progression and survival, with only two original studies published, is the Nrf2 (-617C/A) polymorphism. The results of these studies showed that there was no individual impact of this polymorphism on the susceptibility towards end stage renal disease (ESRD) development, oxidative phenotype and mortality. However, Nrf2 had a significant role in ESRD risk and survival, when combined with other antioxidant genes. The results regarding the impact of SOD2 (Ala16Val) and GPX1 (Pro198Leu) polymorphisms on either CKD or ESRD are still inconclusive. Namely, some studies showed that patients having variant SOD2 (Val) or GPX1 (Leu) allele were at increased risk of CKD development and progression, while other studies reported only weak or no association between these polymorphisms and CKD. Surprisingly, the only study that reported an association of GPX1 polymorphism with overall/cardiovascular survival in ESRD patients showed a significant impact of low activity GPX1 (Leu/Leu) genotype on better survival. In this review, we comprehensively and critically appraise the literature on these polymorphisms related to oxidative stress in CKD patients, in order to identify gaps and provide recommendations for further clinical research and translation. New developments in the field of antioxidant polymorphisms in CKD patients could lead to better stratification of CKD patients, based on a prognostic antioxidant gene panel, and provide a more personalised medicine approach for the need of antioxidant therapy in these patients.

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.

Immune Dysfunction in Uremia 2020

Cardiovascular disease and infections are major causes for the high incidence of morbidity and mortality of patients with chronic kidney disease. Both complications are directly or indirectly associated with disturbed functions or altered apoptotic rates of polymorphonuclear leukocytes, monocytes, lymphocytes, and dendritic cells. Normal responses of immune cells can be reduced, leading to infectious diseases or pre-activated/primed, giving rise to inflammation and subsequently to cardiovascular disease. This review summarizes the impact of kidney dysfunction on the immune system. Renal failure results in disturbed renal metabolic activities with reduced renin, erythropoietin, and vitamin D production, which adversely affects the immune system. Decreased kidney function also leads to reduced glomerular filtration and the retention of uremic toxins. A large number of uremic toxins with detrimental effects on immune cells have been identified. Besides small water-soluble and protein-bound compounds originating from the intestinal microbiome, several molecules in the middle molecular range, e.g., immunoglobulin light chains, retinol-binding protein, the neuropeptides Met-enkephalin and neuropeptide Y, endothelin-1, and the adipokines leptin and resistin, adversely affect immune cells. Posttranslational modifications such as carbamoylation, advanced glycation products, and oxidative modifications contribute to uremic toxicity. Furthermore, high-density lipoprotein from uremic patients has an altered protein profile and thereby loses its anti-inflammatory properties.

Aldosterone Induces DNA Damage and Activation of Nrf2 Mainly in Tubuli of Mouse Kidneys

Hypertensive patients have an increased risk of developing chronic kidney disease (CKD). Many of these patients have increased levels of the blood pressure regulating mineralocorticoid aldosterone. As a protection against aldosterone-induced damage, kidney cells can upregulate key regulators of the antioxidant defense, such as nuclear factor-erythroid-2-related factor 2 (Nrf2). In the present study aldosterone-induced kidney damage and Nrf2 activation in kidney cells of mice treated with three different concentrations of aldosterone for 4 weeks was localized. Increased albumin and neutrophil gelatinase-associated lipocalin (NGAL) in urine revealed an impaired kidney function of the aldosterone-infused mice. Localization of aldosterone-induced oxidative damage (in the form of DNA lesions) in specific kidney cells showed an increase in proximal tubuli and to an even greater extend in distal tubuli. Phosphorylated Nrf2 was increased in distal tubule cells after aldosterone-infusion. Nrf2 activation in proximal tubuli or in glomeruli after aldosterone-treatment could not be observed. Nrf2 target genes and proteins analyzed, paradoxically, showed a downregulation in the whole kidney. Aldosterone-treated mice exhibited an increased kidney injury and DNA damage in distal and proximal tubuli. Nrf2 seemed only to be specifically activated in distal tubule cells, where we also detected the highest amount of oxidative damage.

Lifestyle, Inflammation, and Vascular Calcification in Kidney Transplant Recipients: Perspectives on Long-Term Outcomes

After decades of pioneering and improvement, kidney transplantation is now the renal replacement therapy of choice for most patients with end-stage kidney disease (ESKD). Where focus has traditionally been on surgical techniques and immunosuppressive treatment with prevention of rejection and infection in relation to short-term outcomes, nowadays, so many people are long-living with a transplanted kidney that lifestyle, including diet and exposure to toxic contaminants, also becomes of importance for the kidney transplantation field. Beyond hazards of immunological nature, a systematic assessment of potentially modifiable-yet rather overlooked-risk factors for late graft failure and excess cardiovascular risk may reveal novel targets for clinical intervention to optimize long-term health and downturn current rates of premature death of kidney transplant recipients (KTR). It should also be realized that while kidney transplantation aims to restore kidney function, it incompletely mitigates mechanisms of disease such as chronic low-grade inflammation with persistent redox imbalance and deregulated mineral and bone metabolism. While the vicious circle between inflammation and oxidative stress as common final pathway of a multitude of insults plays an established pathological role in native chronic kidney disease, its characterization post-kidney transplant remains less than satisfactory. Next to chronic inflammatory status, markedly accelerated vascular calcification persists after kidney transplantation and is likewise suggested a major independent mechanism, whose mitigation may counterbalance the excess risk of cardiovascular disease post-kidney transplant. Hereby, we first discuss modifiable dietary elements and toxic environmental contaminants that may explain increased risk of cardiovascular mortality and late graft failure in KTR. Next, we specify laboratory and clinical readouts, with a postulated role within persisting mechanisms of disease post-kidney transplantation (i.e., inflammation and redox imbalance and vascular calcification), as potential non-traditional risk factors for adverse long-term outcomes in KTR. Reflection on these current research opportunities is warranted among the research and clinical kidney transplantation community.

Superoxide Dismutase 2 Val16Ala Polymorphism is Associated with Amiodarone-Associated Liver Injury

Association of SOD2 V16A single-nucleotide polymorphism (rs4880) with drug hepatotoxicity were reported but relationships with amiodarone prescriptions remained unexplored. Research was an exploratory, controlled prospective clinical trial. Patients hospitalized and treated in Clinical Center in Kragujevac, Serbia (in year 2017) were divided into experimental (using amiodarone, having liver injury, n=29, 19 males, the mean age 66.8±10.4 years), control A (neither amiodarone use nor hepatotoxicity, n=29, 19, 66.1±10.3) and control B group (using amiodarone, not having hepatotoxicity, n=29, 19, 66.8±9.8). From blood samples, among other routine biochemistry, genotyping for SOD2 polymorphism Val16Ala was conducted using real-time PCR method with TaqMan® Genotyping Master Mix and TaqMan® DME Genotyping Assay for rs4880. Patients taking amiodarone and having liver injury were mostly carriers of Val/Val (TT) genotype (13 of 24 patients, 54.2%) while Val/Ala (TC) and Ala/Ala (CC) genotypes prevailed in control group A (19 of 40, 47.5%) and control group B (9 of 23, 39.1%), respectively (2=10.409, p=0.034). Frequency of Val (T) and Ala (C) alleles were 0.51 and 0.49, respectively in the whole study sample (Hardy Weinberg equilibrium, 2=0.56, p=0.454). Carriers of TT genotype had significantly higher ALT (437.0±1158.0 vs 81.9131.5 U/L), total bilirubin (28.320.5 vs 15.313.0 mol/L) and total bile acid concentrations (10.910.2 vs 6.45.3 mol/L) compared to carriers of TC genotype (U=2.331, p=0.020, U=3.204, p=0.001 and U=2.172, p=0.030, respectively). Higher incidence of 47T allele of SOD2 was inpatients with amiodarone-associated liver injury as compared to patients on amiodarone not experiencing hepatotoxic effects.