Evaluating the Oxidative Stress in Renal Diseases: What Is the Role for S-Glutathionylation?

The Role of S-Glutathionylation in Health and Disease: A Bird's Eye View

Protein glutathionylation is a reversible post-translational modification that involves the attachment of glutathione to cysteine residues. It plays a role in the regulation of several cellular processes and protection against oxidative damage. Glutathionylation (GS-ylation) modulates protein function, inhibits or enhances enzymatic activity, maintains redox homeostasis, and shields several proteins from irreversible oxidative stress. Aberrant GS-ylation patterns are thus implicated in various diseases, particularly those associated with oxidative stress and inflammation, such as cardiovascular diseases, neurodegenerative disorders, cancer, and many others. Research in the recent years has highlighted the potential to manipulate protein GS-ylation for therapeutic purposes with strategies that imply both its enhancement and inhibition according to different cases. Moreover, it has become increasingly evident that monitoring the GS-ylation status of selected proteins offers diagnostic potential in different diseases. In this review, we try to summarize recent research in the field with a focus on our current understanding of the molecular mechanisms related to aberrant protein GS-ylation.

Association between oxidative balance score in adults with and without chronic kidney disease: 2011-2028 NHANES

Introduction

Oxidative stress status is associated with CKD; however, few studies have investigated this association. The oxidative balance score (OBS) reflects systemic stress status and consists of 16 anti-and pro-oxidant dietary factors and four anti-and pro-oxidant lifestyle factors. Higher OBS implies exposure to more antioxidants. The purpose of this study was to explore the association between OBS and CKD.

Methods

We enrolled 8,134 study participants from the 2011-2018 National Health and Nutrition Examination Survey and obtained OBS by adding the 20 dietary and lifestyle factors. Based on OBS, the participants were divided into three groups. We performed logistic regression, subgroup analyzes, and restricted cubic spline regression to explore the association between OBS and CKD. In addition, we tested the adjusted model.

Results

OBS was negatively associated with CKD (OR: 0.54; 0.66, 0.82). After adjusting for all confounders, when dietary OBS was >20, the prevalence of CKD was reduced by 42% for each unit increase in OBS (p < 0.05). The negative associations of total OBS, dietary OBS, and lifestyle OBS with CKD were more significant in the female group. When the total OBS was ~20, the trend of decreasing prevalence in the female group was more significant.

Conclusion

OBS is negatively associated with chronic kidney disease.

NAC Pre-Administration Prevents Cardiac Mitochondrial Bioenergetics, Dynamics, Biogenesis, and Redox Alteration in Folic Acid-AKI-Induced Cardio-Renal Syndrome Type 3

The incidence of kidney disease is increasing worldwide. Acute kidney injury (AKI) can strongly favor cardio-renal syndrome (CRS) type 3 development. However, the mechanism involved in CRS development is not entirely understood. In this sense, mitochondrial impairment in both organs has become a central axis in CRS physiopathology. This study aimed to elucidate the molecular mechanisms associated with cardiac mitochondrial impairment and its role in CRS development in the folic acid-induced AKI (FA-AKI) model. Our results showed that 48 h after FA-AKI, the administration of N-acetyl-cysteine (NAC), a mitochondrial glutathione regulator, prevented the early increase in inflammatory and cell death markers and oxidative stress in the heart. This was associated with the ability of NAC to protect heart mitochondrial bioenergetics, principally oxidative phosphorylation (OXPHOS) and membrane potential, through complex I activity and the preservation of glutathione balance, thus preventing mitochondrial dynamics shifting to fission and the decreases in mitochondrial biogenesis and mass. Our data show, for the first time, that mitochondrial bioenergetics impairment plays a critical role in the mechanism that leads to heart damage. Furthermore, NAC heart mitochondrial preservation during an AKI event can be a valuable strategy to prevent CRS type 3 development.

Protein Structure and Modification of Aquaporins

Aquaporins (AQPs) allow water molecules and other small, neutral solutes to quickly pass through membrane. The protein structures of AQPs solved by crystallographic methods or cryo-electron microscopy technology show that AQP monomer consists of six membrane-spanning alpha-helices that form the central water-transporting pore. AQP monomers assemble to form tetramers, forming the functional units in the membrane, to transport water or other small molecules. The biological functions of AQPs are regulated by posttranslational modifications, e.g., phosphorylation, ubiquitination, glycosylation, subcellular distribution, degradation and protein interactions. Modifications of AQP combined with structural properties contribute to a better functional mechanism of AQPs. Insight into the molecular mechanisms responsible for AQP modifications as well as gating and transport properties proved to be fundamental to the development of new therapeutic targets or reliable diagnostic and prognostic biomarkers.

Female and male mice have differential longterm cardiorenal outcomes following a matched degree of ischemia-reperfusion acute kidney injury

Acute kidney injury (AKI) is common in patients, causes systemic sequelae, and predisposes patients to long-term cardiovascular disease. To date, studies of the effects of AKI on cardiovascular outcomes have only been performed in male mice. We recently demonstrated that male mice developed diastolic dysfunction, hypertension and reduced cardiac ATP levels versus sham 1 year after AKI. The effects of female sex on long-term cardiac outcomes after AKI are unknown. Therefore, we examined the 1-year cardiorenal outcomes following a single episode of bilateral renal ischemia-reperfusion injury in female C57BL/6 mice using a model with similar severity of AKI and performed concomitantly to recently published male cohorts. To match the severity of AKI between male and female mice, females received 34 min of ischemia time compared to 25 min in males. Serial renal function, echocardiograms and blood pressure assessments were performed throughout the 1-year study. Renal histology, and cardiac and plasma metabolomics and mitochondrial function in the heart and kidney were evaluated at 1 year. Measured glomerular filtration rates (GFR) were similar between male and female mice throughout the 1-year study period. One year after AKI, female mice had preserved diastolic function, normal blood pressure, and preserved levels of cardiac ATP. Compared to males, females demonstrated pathway enrichment in arginine metabolism and amino acid related energy production in both the heart and plasma, and glutathione in the plasma. Cardiac mitochondrial respiration in Complex I of the electron transport chain demonstrated improved mitochondrial function in females compared to males, regardless of AKI or sham. This is the first study to examine the long-term cardiac effects of AKI on female mice and indicate that there are important sex-related cardiorenal differences. The role of female sex in cardiovascular outcomes after AKI merits further investigation.

Penthorum chinense Pursh Compound Ameliorates AFB1-Induced Oxidative Stress and Apoptosis via Modulation of Mitochondrial Pathways in Broiler Chicken Kidneys

Aflatoxin B1 (AFB1) is a carcinogenic mycotoxin widely present in foods and animal feeds; it represents a great risk to human and animal health. The aim of this study was to investigate the protective effects of Penthorum chinense Pursh compound (PCPC) against AFB1-induced damage, oxidative stress, and apoptosis via mitochondrial pathways in kidney tissues of broilers. One-day-old chickens (n = 180) were randomly allocated to six groups: control, AFB1 (2.8 mg AFB1/kg feed), positive drug (10 mLYCHT/kg feed), and PCPC high, medium, and low-dose groups (15, 10, and 5 ml PCPC/kg feed, respectively). AFB1 treatment reduced weight gain and induced oxidative stress and kidney damage in broiler tissues; however, PCPC supplementation effectively enhanced broiler performance, ameliorated AFB1-induced oxidative stress, and inhibited apoptosis in the kidneys of broilers. The mRNA expression levels of mitochondria-related apoptosis genes (Bax, Bak, cytochrome c, caspase-9, and caspase-3) were significantly increased, whereas BCL2 expression level decreased in the AFB1 group. Supplementation of PCPC to the AFB1 group significantly reversed the changes in mRNA expression levels of these apoptosis-associated genes compared to those in the AFB1 group. The mRNA levels of NRF2 and HMOX1 in the kidneys of the AFB1 group were significantly reduced compared to those in the control group, whereas PCPC significantly increased the NRF2 and HMOX1 mRNA levels. AFB1 decreased the levels of Beclin1, LC3-I, and LC3-II and increased P53 levels in the kidney compared to those in the control, whereas PCPC significantly reversed these changes to normal levels of autophagy-related genes compared to those in the AFB1 group. In conclusion, our findings demonstrated that PCPC ameliorated AFB1-induced oxidative stress by regulating the expression of apoptosis-related genes and mitochondrial pathways. Our results suggest that PCPC represents a natural and safe agent for preventing AFB1-induced injury and damage in broiler tissues.

Redox Regulation by Protein S-Glutathionylation: From Molecular Mechanisms to Implications in Health and Disease

S-glutathionylation, the post-translational modification forming mixed disulfides between protein reactive thiols and glutathione, regulates redox-based signaling events in the cell and serves as a protective mechanism against oxidative damage. S-glutathionylation alters protein function, interactions, and localization across physiological processes, and its aberrant function is implicated in various human diseases. In this review, we discuss the current understanding of the molecular mechanisms of S-glutathionylation and describe the changing levels of expression of S-glutathionylation in the context of aging, cancer, cardiovascular, and liver diseases.

Development of Fortified Citrus Olive Oils: From Their Production to Their Nutraceutical Properties on the Cardiovascular System

: Recently the use of food by-products as natural sources of biologically active substances has been extensively investigated especially for the development of functional foods fortified with natural antioxidants. Due to their content of bioactive compounds, such as carotenoids, flavonoids and limonoids, citrus peels could be suitable to formulate enriched olive oils able to boost healthy nutrition. The aim of this study was: (i) to determine the compositional and sensory profiles of citrus olive oil; and (ii) to evaluate its nutraceutical properties in rats with high fat diet-induced metabolic syndrome and oxidative stress. The results obtained show the potential of using citrus peels as a source of bioactive compounds to improve the sensory profile as well as the phytochemical composition of olive oil. We demonstrated that the production system of Citrus x aurantium olive oil and Citrus limon olive oil improves its organoleptic properties without altering its beneficial effects, which, like control extra virgin olive oil, showed protective effects relating to glucose and serum lipid levels, metabolic activity of adipocytes, myocardial tissue functionality, oxidative stress markers and endothelial function at blood vessel level.

Sex differences in redox homeostasis in renal disease

Sex differences in redox signaling in the kidney present new challenges and opportunities for understanding the physiology and pathophysiology of the kidney. This review will focus on reactive oxygen species, immune-related signaling pathways and endothelin-1 as potential mediators of sex-differences in redox homeostasis in the kidney. Additionally, this review will highlight male-female differences in redox signaling in several major cardiovascular and renal disorders namely acute kidney injury, diabetic nephropathy, kidney stone disease and salt-sensitive hypertension. Furthermore, we will discuss the contribution of redox signaling in the pathogenesis of postmenopausal hypertension and preeclampsia.

Cold-Pressing Olive Oil in the Presence of Cryomacerated Leaves of Olea or Citrus: Nutraceutical and Sensorial Features

The nutraceutical properties of extra-virgin olive oil (EVOO) can be further improved by the addition of olive leaves during olive pressing. However, while Citrus leaves are rich sources of bioactive substances, no data are available in the literature about the effect of Citrus leaf addition on the nutraceutical and sensorial profiles of olive oil. This study aimed at comparing the chemical and sensorial qualities of olive oils obtained from ripe olives pressed together with either Olea or Citrus spp. (lemon or orange) cryomacerated leaves. General composition parameters as well as major antioxidants and antioxidant activity were measured. A panel test evaluation, as well as headspace volatile characterization (headspace solid phase microextraction, HS-SPME), were also performed. All data were compared with an EVOO extracted from the same olive batch used as control. It was possible to obtain Leaf Olive Oils (LOOs) characterized by a higher (p < 0.05) content of antioxidants, compared to the control sample, and the highest oleuropein concentration was detected in the olive oil extracted in presence of olive leaf (+50% in comparison with the control). All the LOOs showed a higher smell complexity and the scent of ripe fruit was generally mitigated. Lemon and olive LOOs showed the best smell profile.

Core-shell structured Fe3O4@GO@MIL-100(Fe) magnetic nanoparticles as heterogeneous photo-Fenton catalyst for 2,4-dichlorophenol degradation under visible light

A novel core-shell structured Fe₃O₄@GO@MIL-100(Fe) magnetic catalyst was successfully synthesized and used as heterogeneous photo-Fenton catalyst for 2,4-dichlorophenl (2,4-DCP) degradation. The catalyst was fully characterized by X-ray diffraction pattern (XRD), Raman spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunner-Emmet-Teller (BET) and magnetic hysteresis loops measurements. The effects of initial pH, H₂O₂ concentration, catalyst load and irradiation intensity on 2,4-DCP degradation were also investigated. The results showed that Fe₃O₄@GO@MIL-100(Fe) exhibited excellent photo-Fenton catalytic activity, achieving almost 100% of 2,4-DCP degradation within 40 min at reaction condition of 3 mmol/L H₂O₂, 50 mg/L 2,4-DCP, pH 5.5 and irradiation intensity of 500 W. The high catalytic activity of Fe₃O₄@GO@MIL-100(Fe) can be attributed to the efficient transfer of photo-generated electrons between MIL-100(Fe) and Fe₃O₄ by GO. The recycling experiments displayed that Fe₃O₄@GO@MIL-100(Fe) catalyst possessed good stability and could be easily recovered under an applied magnetic field. Finally, the possible mechanism of 2,4-DCP degradation in the photo-Fenton system catalyzed by Fe₃O₄@GO@MIL-100(Fe) was also proposed according to the analyses of reactive species, photoluminescence (PL) emission spectra and the photocurrent responses.

Lycopene attenuates AFB1-induced renal injury with the activation of the Nrf2 antioxidant signaling pathway in mice

Oxidative stress is an important molecular mechanism for kidney injury in aflatoxin B1 (AFB1) nephrotoxicity. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a master transcription factor for regulating the cellular oxidative stress response, which has been confirmed in animal models. Lycopene (LYC), a natural carotenoid, has received extensive attention due to its antioxidant effect with the activation of Nrf2. However, the role of LYC in protecting against AFB1-induced renal injury is unknown. To evaluate the chemoprotective effect of LYC on AFB1-induced renal injury, forty-eight male mice were randomly divided into 4 groups and treated with LYC (5 mg per kg of bodyweight) and/or AFB1 (0.75 mg per kg of bodyweight) by intragastric administration for 30 days. AFB1 and LYC were respectively dissolved in olive oil. We found that AFB1 exposure significantly increased the serum concentrations of blood urea nitrogen (BUN) and serum creatinine (SCR), and caused damage to the renal structure. Notably, LYC potentially alleviated AFB1-induced kidney lesions through attenuating AFB1-induced oxidative stress. Renal nuclear factor-erythroid 2-related factor 2 (Nrf2) and its downstream target gene (CAT, NQO1, SOD1, GSS, GCLM and GCLC) translation and protein expression were ameliorated by pretreatment with LYC in AFB1-exposed mice. These results suggested that LYC potentially alleviates AFB1-induced renal injury. This effect may be attributed to the enhancement of renal antioxidant capacity with the activation of the Nrf2 antioxidant signaling pathway.

Green olive leaf extract (OLE) provides cytoprotection in renal cells exposed to low doses of cadmium

Cadmium (Cd) is a heavy and highly toxic metal that contaminates air, food and water. Cadmium accumulates in several organs altering normal functions. The kidney is the major organ at risk of damage from chronic exposure to cadmium as a contaminant in food and water. This study aims to investigate the beneficial effects of OLE in renal collecting duct MCD4 cells exposed to a low dose cadmium (1 μM). In MCD4 cells cadmium caused an increase in ROS production, as well as generation of lipid droplets and reduced cell viability. Moreover, cadmium exposure led to a remarkable increase in the frequency of micronuclei and DNA double-strand breaks, assessed using the alkaline comet assay. In addition, cadmium dramatically altered cell cytoskeleton architecture and caused S-glutathionylation of actin. Notably, all cadmium-induced cellular deregulations were prevented by co-treatment with OLE, possibly due to its antioxidant action and to the presence of bioactive phytocompounds. Indeed, OLE treatment attenuated Cd-induced actin S-glutathionylation, thereby stabilizing actin filaments. Taken together, these observations provide a novel insight into the biological action of OLE in renal cells and support the notion that OLE may serve as a potential adjuvant against cadmium-induced nephrotoxicity.

Protective effects of N-acetyl-cysteine in mitochondria bioenergetics, oxidative stress, dynamics and S-glutathionylation alterations in acute kidney damage induced by folic acid

Folic acid (FA)-induced acute kidney injury (AKI) is a widely used model for studies of the renal damage and its progression to chronic state. However, the molecular mechanisms by which FA induces AKI remain poorly understood. Since renal function depends on mitochondrial homeostasis, it has been suggested that mitochondrial alterations contribute to AKI development. Additionally, N-acetyl-cysteine (NAC) can be a protective agent to prevent mitochondrial and renal dysfunction in this model, given its ability to increase mitochondrial glutathione (GSH) and to control the S-glutathionylation levels, a reversible post-translational modification that has emerged as a mechanism able to link mitochondrial energy metabolism and redox homeostasis. However, this hypothesis has not been explored. The present study demonstrates for the first time that, at 24 h, FA induced mitochondrial bioenergetics, redox state, dynamics and mitophagy alterations, which are involved in the mechanisms responsible for the AKI development. On the other hand, NAC preadministration was able to prevent mitochondrial bioenergetics, redox state and dynamics alterations as well as renal damage. The protective effects of NAC on mitochondria and renal function could be related to its observed capacity to preserve the S-glutathionylation process and GSH levels in mitochondria. Taken together, our results support the idea that these mitochondrial processes can be targets for the prevention of the renal damage and its progression in FA-induced AKI model.

Mitochondrial bioenergetics, redox state, dynamics and turnover alterations in renal mass reduction models of chronic kidney diseases and their possible implications in the progression of this illness

Nowadays, chronic kidney disease (CKD) is considered a worldwide public health problem. CKD is a term used to describe a set of pathologies that structurally and functionally affect the kidney, it is mostly characterized by the progressive loss of kidney function. Current therapeutic approaches are insufficient to avoid the development of this disease, which highlights the necessity of developing new strategies to reverse or at least delay CKD progression. Kidney is highly dependent on mitochondrial homeostasis and function, consequently, the idea that mitochondrial pathologies could play a pivotal role in the genesis and development of kidney diseases has risen. Although many research groups have recently published studies of mitochondrial function in acute kidney disease models, the existing information about CKD is still limited, especially in renal mass reduction (RMR) models. This paper focuses on reviewing current experimental information about the bioenergetics, dynamics (fission and fusion processes), turnover (mitophagy and biogenesis) and redox mitochondrial alterations in RMR, to discuss and integrate the mitochondrial changes triggered by nephron loss, as well as its relationship with loss of kidney function in CKD, in these models. Understanding these mechanisms would allow us to design new therapies that target these mitochondrial alterations.

Aquaporin Membrane Channels in Oxidative Stress, Cell Signaling, and Aging: Recent Advances and Research Trends

Reactive oxygen species (ROS) are produced as a result of aerobic metabolism and as by-products through numerous physiological and biochemical processes. While ROS-dependent modifications are fundamental in transducing intracellular signals controlling pleiotropic functions, imbalanced ROS can cause oxidative damage, eventually leading to many chronic diseases. Moreover, increased ROS and reduced nitric oxide (NO) bioavailability are main key factors in dysfunctions underlying aging, frailty, hypertension, and atherosclerosis. Extensive investigation aims to elucidate the beneficial effects of ROS and NO, providing novel insights into the current medical treatment of oxidative stress-related diseases of high epidemiological impact. This review focuses on emerging topics encompassing the functional involvement of aquaporin channel proteins (AQPs) and membrane transport systems, also allowing permeation of NO and hydrogen peroxide, a major ROS, in oxidative stress physiology and pathophysiology. The most recent advances regarding the modulation exerted by food phytocompounds with antioxidant action on AQPs are also reviewed.

2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino) phenyl carbamoylsulfanyl] propionic acid, a glutathione reductase inhibitor, induces G2/M cell cycle arrest through generation of thiol oxidative stress in human esophageal cancer cells

Esophageal squamous cell carcinoma (ESCC) is a highly malignant cancer with poor response to both of chemotherapy and radiotherapy. 2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino) phenyl carbamoylsulfanyl] propionic acid (2-AAPA), an irreversible inhibitor of glutathione reductase (GR), is able to induce intracellular oxidative stress, and has shown anticancer activity in many cancer cell lines. In this study, we investigated the effects of 2-AAPA on the cell proliferation, cell cycle and apoptosis and aimed to explore its mechanism of action in human esophageal cancer TE-13 cells. It was found that 2-AAPA inhibited growth of ESCC cells in a dose-dependent manner and it did not deplete reduced glutathione (GSH), but significantly increased the oxidized form glutathione (GSSG), resulting in decreased GSH/GSSG ratio. In consequence, significant reactive oxygen species (ROS) production was observed. The flow cytometric analysis revealed that 2-AAPA inhibited growth of esophageal cancer cells through arresting cell cycle in G₂/M phase, but apoptosis-independent mechanism. The G₂/M arrest was partially contributed by down-regulation of protein expression of Cdc-25c and up-regulation of phosphorylated Cdc-2 (Tyr15), Cyclin B1 (Ser147) and p53. Meanwhile, 2-AAPA-induced thiol oxidative stress led to increased protein S-glutathionylation, which resulted in α-tubulin S-glutathionylation-dependent depolymerization of microtubule in the TE-13 cells. In conclusion, we identified that 2-AAPA as an effective thiol oxidative stress inducer and proliferation of TE-13 cells were suppressed by G₂/M phase cell cycle arrest, mainly, through α-tubulin S-glutathionylation-mediated microtubule depolymerization. Our results may introduce new target and approach for esophageal cancer therapy through generation of GR-mediated thiol oxidative stress.

Effects of Ganoderma Lucidum shell-broken spore on oxidative stress of the rabbit urinary bladder using an in vivo model of ischemia/reperfusion

Oxidative stress plays an important role in specific disease pathophysiology and the aging process. In the history of human kind, many herbs were utilized for disease prevention and anti-aging treatment. However, there are few direct evidences provided by modern laboratory technology. The current study was designed to evaluate Ganoderma Lucidum's (GL) ability to reduce the damage from in vivo ischemia/reperfusion (I/R) using a rabbit model of I/R that has been effectively utilized to prove the effects of drugs and supplements to reduce oxidative stress. Urinary bladder dysfunction secondary to benign prostatic hyperplasia (BPH) is a major affliction of aging men. One of the major etiologies of obstructive bladder dysfunction (OBD) is oxidative stress induced by I/R. Pharmaceutical studies and clinical research have proven that GL is useful in helping to prevent certain types of pathology and also helpful in prolonging human life in part by acting as an antioxidant. Using an in vivo model of I/R, we have investigated the ability of GL to protect bladder function from oxidative damage mediated by I/R. Our studies demonstrated that ischemia followed by reperfusion resulted in a significant decrease in bladder compliance and decreases in the contractile responses to a variety of forms of contractile stimulation. Pretreatment of rabbits with Ganoderma Lucidum prior to subjecting the rabbits to I/R completely inhibited the negative effects of I/R on both the compliance and contractile responses. These results demonstrate that Ganoderma provides excellent protection of bladder function following I/R (oxidative stress).