Tempol, a membrane-permeable radical scavenger, reduces oxidant stress-mediated renal dysfunction and injury in the rat

Hippo pathway activated by circulating reactive oxygen species mediates cardiac diastolic dysfunction after acute kidney injury

Acute kidney injury (AKI) can cause distal cardiac dysfunction; however, the underlying mechanism is unknown. Oxidative stress is proved prominent in AKI-induced cardiac dysfunction, and a possible bridge role of oxidative-stress products in cardio-renal interaction has been reported. Therefore, this study aimed to investigate the critical role of circulating reactive oxygen species (ROS) in mediating cardiac dysfunction after bilateral renal ischemia-reperfusion injury (IRI). We observed the diastolic dysfunction in the mice following renal IRI, accompanied by reduced ATP levels, oxidative stress, and branched-chain amino acids (BCAA) accumulation in the heart. Notably, ROS levels showed a sequential increase in the kidneys, circulation, and heart. Treatment with tempol, an ROS scavenger, significantly restored cardiac diastolic function in the renal IRI mice, corroborating the bridge role of circulating ROS. Accumulating evidence has identified oxidative stress as upstream of Mst1/Hippo in cardiac injury, which could regulate the expression of downstream genes related to mitochondrial quality control, leading to lower ATP, higher ROS and metabolic disorder. To verify this, we examined the activation of the Mst1/Hippo pathway in the heart of renal IRI mice, which was alleviated by tempol treatment as well. In vitro, analysis revealed that Mst1-knockdown cardiomyocytes could be activated by hydrogen peroxide (H2O2). Analysis of Mst1-overexpression cardiomyocytes confirmed the critical role of the Mst1/Hippo pathway in oxidative stress and BCAA dysmetabolism. Therefore, our results indicated that circulating ROS following renal IRI activates the Mst1/Hippo pathway of myocardium, leading to cardiac oxidative stress and diastolic dysfunction. This finding provides new insights for the clinical exploration of improved treatment options for cardiorenal syndrome.

Excessive iron deposition in root apoplast is involved in growth arrest of roots in response to low pH

The rhizotoxicity of protons (H+) in acidic soils is a fundamental constraint that results in serious yield losses. However, the mechanisms underlying H+-mediated inhibition of root growth are poorly understood. In this study, we revealed that H+-induced root growth inhibition in Arabidopsis depends considerably on excessive iron deposition in the root apoplast. Reducing such aberrant iron deposition by decreasing the iron supply or disrupting the ferroxidases LOW PHOSPHATE ROOT 1 (LPR) and LPR2 attenuates the inhibitory effect of H+ on primary root growth efficiently. Further analysis showed that excessive iron deposition triggers a burst of highly reactive oxygen species, consequently impairing normal root development. Our study uncovered a valuable strategy for improving the ability of plants to tolerate H+ toxicity by manipulating iron availability.

Aged polystyrene microplastics exacerbate alopecia associated with tight junction injuries and apoptosis via oxidative stress pathway in skin

Microplastics (MPs) are pervasive pollutants in the natural environment and contribute to increased levels of illness in both animals and humans. However, thespecific impacts of MPs on skin damage and alopeciaare not yet well understood. In this study, we have examined the effects of two types of polystyrene MPs (pristine and aged) on skin and hair follicle damage in mice. UV irradiation changed the chemical and physical properties of the aged MPs, including functional groups, surface roughness, and contact angles. In both in vivo and in vitro experiments, skin and cell injuries related to oxidative stress, apoptosis, tight junctions (TJs), alopecia, mitochondrial dysfunction, and other damages were observed. Mechanistically, MPs and aged MPs can induce TJs damage via the oxidative stress pathway and inhibition of antioxidant-related proteins, and this can lead to alopecia. The regulation of cell apoptosis was also observed, and this is involved in the ROS-mediated mitochondrial signaling pathway. Importantly, aged MPs showed exacerbated toxicity, which may be due to their elevated surface irregularities and altered chemical compositions. Collectively, this study suggests a potential therapeutic approach for alopecia and hair follicle damage caused by MPs pollution.

N-acetylcysteine regulates oxalate induced injury of renal tubular epithelial cells through CDKN2B/TGF-β/SMAD axis

This study was aimed to investigate the preventive effects of N-acetyl-L-cysteine (NAC) against renal tubular cell injury induced by oxalate and stone formation and further explore the related mechanism. Transcriptome sequencing combined with bioinformatics analysis were performed to identify differentially expressed gene (DEG) and related pathways. HK-2 cells were pretreated with or without antioxidant NAC/with or silencing DEG before exposed to sodium oxalate. Then, the cell viability, oxidative biomarkers of superoxidase dismutase (SOD) and malondialdehyde (MDA), apoptosis and cell cycle were measured through CCK8, ELISA and flow cytometry assay, respectively. Male SD rats were separated into control group, hyperoxaluria (HOx) group, NAC intervention group, and TGF-β/SMAD pathway inhibitor group. After treatment, the structure changes and oxidative stress and CaOx crystals deposition were evaluated in renal tissues by H&E staining, immunohistochemical and Pizzolato method. The expression of TGF-β/SMAD pathway related proteins (TGF-β1, SMAD3 and SMAD7) were determined by Western blot in vivo and in vitro. CDKN2B is a DEG screened by transcriptome sequencing combined with bioinformatics analysis, and verified by qRT-PCR. Sodium oxalate induced declined HK-2 cell viability, in parallel with inhibited cellular oxidative stress and apoptosis. The changes induced by oxalate in HK-2 cells were significantly reversed by NAC treatment or the silencing of CDKN2B. The cell structure damage and CaOx crystals deposition were observed in kidney tissues of HOx group. Meanwhile, the expression levels of SOD and 8-OHdG were detected in kidney tissues of HOx group. The changes induced by oxalate in kidney tissues were significantly reversed by NAC treatment. Besides, expression of SMAD7 was significantly down-regulated, while TGF-β1 and SMAD3 were accumulated induced by oxalate in vitro and in vivo. The expression levels of TGF-β/SMAD pathway related proteins induced by oxalate were reversed by NAC. In conclusion, we found that NAC could play an anti-calculus role by mediating CDKN2B/TGF-β/SMAD axis.

Assessing the effects of tempol on renal fibrosis, inflammation, and oxidative stress in a high-salt diet combined with 5/6 nephrectomy rat model: utilizing oxidized albumin as a biomarker

BACKGROUND

Oxidative stress has been implicated in the pathogenesis of chronic kidney disease (CKD), prompting the exploration of antioxidants as a potential therapeutic avenue for mitigating disease progression. This study aims to investigate the beneficial impact of Tempol on the progression of CKD in a rat model utilizing oxidized albumin as a biomarker.

METHODS

After four weeks of treatment, metabolic parameters, including body weight, left ventricle residual weight, kidney weight, urine volume, and water and food intake, were measured. Systolic blood pressure, urinary protein, oxidized albumin level, serum creatinine (Scr), blood urea nitrogen (BUN), 8-OHdG, TGF-β1, and micro-albumin were also assessed. Renal fibrosis was evaluated through histological and biochemical assays. P65-NF-κB was quantified using an immunofluorescence test, while Smad3, P65-NF-κB, and Collagen I were measured using western blot. TNF-α, IL-6, MCP-1, TGF-β1, Smad3, and P65-NF-κB were analyzed by RT-qPCR.

RESULTS

Rats in the high-salt diet group exhibited impaired renal function, characterized by elevated levels of blood urea nitrogen, serum creatinine, 8-OHdG, urine albumin, and tubulointerstitial damage, along with reduced body weight. However, these effects were significantly ameliorated by Tempol administration. In the high-salt diet group, blood pressure, urinary protein, and oxidized albumin levels were notably higher compared to the normal diet group, but Tempol administration in the treatment group reversed these effects. Rats in the high-salt diet group also displayed increased levels of proinflammatory factors (TNF-α, IL-6, MCP1) and profibrotic factors (NF-κB activation, Collagen I), elevated expression of NADPH oxidation-related subunits (P65), and activation of the TGF-β1/Smad3 signaling pathway. Tempol treatment inhibited NF-κB-mediated inflammation and TGF-β1/Smad3-induced renal fibrosis signaling pathway activation.

CONCLUSION

These findings suggest that Tempol may hold therapeutic potential for preventing and treating rats undergoing 5/6 nephrectomy. Further research is warranted to elucidate the mechanisms underlying Tempol's protective effects and its potential clinical applications. Besides, there is a discernible positive relationship between oxidized albumin and other biomarkers, such as 8-OHG, urinary protein levels, mALB, Scr, BUN, and TGF-β1 in a High-salt diet combined with 5/6 nephrectomy rat model. These findings suggest the potential utility of oxidized albumin as a sensitive indicator for oxidative stress assessment.

The Cellular and Organismal Effects of Nitroxides and Nitroxide-Containing Nanoparticles

Nitroxides are stable free radicals that have antioxidant properties. They react with many types of radicals, including alkyl and peroxyl radicals. They act as mimics of superoxide dismutase and stimulate the catalase activity of hemoproteins. In some situations, they may exhibit pro-oxidant activity, mainly due to the formation of oxoammonium cations as products of their oxidation. In this review, the cellular effects of nitroxides and their effects in animal experiments and clinical trials are discussed, including the beneficial effects in various pathological situations involving oxidative stress, protective effects against UV and ionizing radiation, and prolongation of the life span of cancer-prone mice. Nitroxides were used as active components of various types of nanoparticles. The application of these nanoparticles in cellular and animal experiments is also discussed.

Vitamin E and Silymarin Reduce Oxidative Tissue Damage during Gentamycin-Induced Nephrotoxicity

Aminoglycoside antibiotics and gentamicin (GN), in particular, are still widely used in clinical practice. It is a well-known fact that GN causes nephrotoxicity, and redox disturbances are discussed as a factor in its side effects. Recently, a new type of cell oxidative death, named ferroptosis, was discovered; it is associated with iron accumulation in the cell, glutathione (GSH) depletion and inactivation of glutathione peroxidase-4 (GPX4), reactive oxygen species (ROS) increment with concomitant lipid peroxidation. In this regard, a possible connection between GN-induced renal damage, ferroptosis and the overall antioxidant status of the organism could be investigated. Moreover, due to its beneficial effects, GN is still one of the main choices as a therapeutic agent for several diseases, and the possible reduction of its side effects with the application of certain antioxidants will be of important clinical significance. The study was conducted with adult male white mice divided into several groups (n = 6). GN nephrotoxicity was induced by the administration of GN 100-200 mg/kg i.p. for 10 days. The control group received only saline. The other groups received either Vitamin E (400 mg/kg p.o.) or Silymarin (200 mg/kg p.o.) applied alone or together with GN for the same period. After the end of the study, the animals were sacrificed, and blood and tissue samples were taken for the assessment of biochemical parameters and antioxidant status, as well as routine and specific for GPX4 histochemistry examination. The experimental results indicate that GN-induced nephrotoxicity negatively modulates GPX4 activity and is associated with increased production of ROS and lipid peroxidation. The groups treated with antioxidants demonstrated preserved antioxidant status and better GPX4 activity. In conclusion, the inhibition of ROS production and especially the suppression of ferroptosis, could be of clinical potential and can be applied as a means of reducing the toxic effects of GN application.

The Sigma-1 Receptor Is a Novel Target for Improving Cold Preservation in Rodent Kidney Transplants

Kidney transplantation is the preferred treatment for patients with end-stage kidney disease. Maintaining organ viability between donation and transplantation, as well as minimizing ischemic injury, are critically important for long-term graft function and survival. Moreover, the increasing shortage of transplantable organs is a considerable problem; thus, optimizing the condition of grafts is a pivotal task. Here, rodent models of kidney transplantation and cold storage were used to demonstrate that supplementation of a preservation solution with Sigma-1 receptor (S1R) agonist fluvoxamine (FLU) reduces cold and warm ischemic injury. Post-transplant kidney function was improved, histological injury was mitigated, and mRNA expression of two tubular injury markers-kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin-was robustly reduced. In addition, renal inflammation was diminished, as shown by reduced leukocyte infiltration and pro-inflammatory cytokine expression. In the cold ischemia model, FLU ameliorated structural injury profoundly after 2 h as well as 24 h. The reduced number of TUNEL-positive and Caspase 3-positive cells suggests the anti-apoptotic effect of FLU. None of these beneficial effects of FLU were observed in S1R^-/- mice. Of note, organ damage in FLU-treated kidneys after 24 h of cold storage was similar to just 2 h without FLU. These results indicate that S1R agonists can prolong storage time and have great potential in improving organ preservation and in alleviating the problem of organ shortages.

Insight into SARS-CoV-2 Omicron variant immune escape possibility and variant independent potential therapeutic opportunities

The Omicron, the latest variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first detected in November 2021 in Botswana, South Africa. Compared to other variants of SARS-CoV-2, the Omicron is the most highly mutated, with 50 mutations throughout the genome, most of which are in the spike (S) protein. These mutations may help the Omicron to evade host immunity against the vaccine. Epidemiological studies suggest that Omicron is highly infectious and spreads rapidly, but causes significantly less severe disease than the wild-type strain and the other variants of SARS-CoV-2. With the increased transmissibility and a higher rate of re-infection, Omicron has now become a dominant variant worldwide and is predicted to be able to evade vaccine-induced immunity. Several clinical studies using plasma samples from individuals receiving two doses of US Food and Drugs Administration (FDA)-approved COVID-19 vaccines have shown reduced humoral immune response against Omicron infection, but T cell-mediated immunity was well preserved. In fact, T cell-mediated immunity protects against severe disease, and thus the disease caused by Omicron remains mild. In this review, I surveyed the current status of Omicron variant mutations and mechanisms of immune response in the context of immune escape from COVID-19 vaccines. I also discuss the potential implications of therapeutic opportunities that are independent of SARS-CoV-2 variants, including Omicron. A better understanding of vaccine-induced immune responses and variant-independent therapeutic interventions that include potent antiviral, antioxidant, and anti-cytokine activities may pave the way to reducing Omicron-related COVID-19 complications, severity, and mortality. Collectively, these insights point to potential research gaps and will aid in the development of new-generation COVID-19 vaccines and antiviral drugs to combat Omicron, its sublineages, or upcoming new variants of SARS-CoV-2.

Klotho, Oxidative Stress, and Mitochondrial Damage in Kidney Disease

Reducing oxidative stress stands at the center of a prevention and control strategy for mitigating cellular senescence and aging. Kidney disease is characterized by a premature aging syndrome, and to find a modulator targeting against oxidative stress, mitochondrial dysfunction, and cellular senescence in kidney cells could be of great significance to prevent and control the progression of this disease. This review focuses on the pathogenic mechanisms related to the appearance of oxidative stress damage and mitochondrial dysfunction in kidney disease. In this scenario, the anti-aging Klotho protein plays a crucial role by modulating signaling pathways involving the manganese-containing superoxide dismutase (Mn-SOD) and the transcription factors FoxO and Nrf2, known antioxidant systems, and other known mitochondrial function regulators, such as mitochondrial uncoupling protein 1 (UCP1), B-cell lymphoma-2 (BCL-2), Wnt/β-catenin, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1 alpha), transcription factor EB, (TFEB), and peroxisome proliferator-activated receptor gamma (PPAR-gamma). Therefore, Klotho is postulated as a very promising new target for future therapeutic strategies against oxidative stress, mitochondria abnormalities, and cellular senescence in kidney disease patients.

Therapeutic Effects of Heterotrigona itama (Stingless Bee) Bee Bread in Improving Hepatic Lipid Metabolism through theActivation of the Keap1/Nrf2 Signaling Pathway in an Obese Rat Model

Bee bread (BB) has traditionally been used as a dietary supplement to treat liver problems. This study evaluated the therapeutic effects of Heterotrigona itama BB from Malaysia on obesity-induced hepatic lipid metabolism disorder via the regulation of the Keap1/Nrf2 pathway. Male Sprague Dawley rats were fed with either a normal diet or high-fat diet (HFD) for 6 weeks to induce obesity. Following 6 weeks, obese rats were treated either with distilled water (OB group), BB (0.5 g/kg body weight/day) (OB + BB group) or orlistat (10 mg/kg body weight/day) (OB + OR group) concurrent with HFD for another 6 weeks. BB treatment suppressed Keap1 and promoted Nrf2 cytoplasmic and nuclear translocations, leading to a reduction in oxidative stress, and promoted antioxidant enzyme activities in the liver. Furthermore, BB down-regulated lipid synthesis and its regulator levels (SIRT1, AMPK), and up-regulated fatty acid β-oxidation in the liver of obese rats, being consistent with alleviated lipid levels, improved hepatic histopathological changes (steatosis, hepatocellular hypertrophy, inflammation and glycogen expression) and prevented progression to non-alcoholic steatohepatitis. These results showed the therapeutic potentials of H. itama BB against oxidative stress and improved lipid metabolism in the liver of obese rats possibly by targeting the Keap1/Nrf2 pathway, hence proposing its role as a natural supplement capable of treating obesity-induced fatty liver disease.

A nonconjugated radical polymer with stable red luminescence in the solid state

Organic radicals are unstable and stable radicals usually display non-luminescent properties. Luminescent radicals possess the all-in-one properties of optoelectronics, electronics, and magnetics. To date, the reported structures of luminescent radicals are limited to triphenylmethyl radical derivatives and their analogues, which are stabilized with extended π-conjugation. Here, we demonstrate the first example of a nonconjugated luminescent radical. In spite of the lack of delocalized π-stabilization, the radical polymer readily emits red luminescence in the solid state. A traditional luminescent quencher, 2,2,6,6-tetramethylpiperidin-1-yl turned into a red chromophore when grafted onto a polymer backbone. Experimental data confirm that the emission is associated with the nitroxide radicals and is also affected by the packing of the polymer. This work discloses a novel class of luminescent radicals and a distinctive pathway for luminescence from open-shell materials.

Orlistat Mitigates Oxidative Stress-Linked Myocardial Damage via NF-κβ- and Caspase-Dependent Activities in Obese Rats

Oxidative stress contributes to major complications of obesity. This study intended to identify whether orlistat could mitigate myocardial damage in obese animal models. The tested rats were divided into two groups and fed either with normal chow (n = 6 per group) or with a high-fat diet (HFD) for 6 weeks to induce obesity (n = 12 per group). Obese rats were further subjected to treatment either with distilled water (OB group) or orlistat 10 mg/kg/day (OB + OR group). Key indices of oxidative stress, inflammation, and apoptosis were assessed using an immunohistochemical-based technique and real-time PCR. The OB group showed significant increases of oxidative stress markers (TBARs and PCO), with significant decreases of anti-oxidant markers (Nrf2, SOD, CAT, and GPx). Furthermore, mRNA expression of pro-inflammatory markers (TNF-α and NF-κβ) and pro-apoptosis markers (Bax, Caspase-3, Caspase-8, and Caspase-9) were significantly upregulated in the OB group. Obese rats developed pathological changes of myocardial damages as evidenced by the presence of myocardial hypertrophy and inflammatory cells infiltration. Orlistat dampened the progression of myocardial damage in obese rats by ameliorating the oxidative stress, and by inhibiting NF-κβ pathway and caspase-dependent cell apoptosis. Our study proposed that orlistat could potentially mitigate oxidative stress-linked myocardial damage by mitigating inflammation and apoptosis, thus rationalizing its medical usage.

Cocoyam (Colocasia esculenta) modulates some parameters of testosterone propionate-induced rat model of benign prostatic hyperplasia

The increased global prevalence of benign prostatic hyperplasia (BPH) and the promising potentials of functional foods in ameliorating it led to this study which reported the effect of aqueous ethanol extract of cocoyam (Colocasia esculenta) tuber on some biochemical indices in testosterone propionate (TP) induced benign prostatic hyperplasia (BPH) rats. Thirty male albino rats were randomly assigned into 6 groups of 5 rats each. Group 1 (negative control) received 3 mg/kg of TP and normal saline, group 2 (positive control) received 3 mg/kg of TP and 5 mg/kg of finasteride; groups 3, 4, and 6 rats received 3 mg/kg of TP and 100, 200 and 400 mg/kg of ethanol extracts of cocoyam respectively while group 5 (normal control) received olive oil + normal saline. The study lasted for 28 days. The negative control had increased prostate weight (p < 0.05), decreased body weight gain, prostatic superoxide dismutase, catalase and glutathione concentrations; no differences (p > 0.05) in the serum total cholesterol, triacylglycerol, Very Low Density Lipoprotein, High Density Lipoprotein, Low Density Lipoprotein concentration but increased (p < 0.05) prostate levels of interleukin 10, prostate specific antigen, testosterone, total proteins and malondialdehyde relative to the normal control. Finasteride or the C. esculenta tuber extract modulated most of these parameters as corroborated by histology of the prostate. The percentage yield of the C. esculenta tuber extract was 1.56% and 23 phenolic compounds were characterized in the tuber. The study showed the potentials of C. esculenta tuber in the management of BPH.

Bee bread attenuates high fat diet induced renal pathology in obese rats via modulation of oxidative stress, downregulation of NF-kB mediated inflammation and Bax signalling

CONTEXT

Global prevalence of obesity is increasing.

OBJECTIVE

To study the effect of bee bread (BB) on serum renal function parameters, oxidative stress, inflammatory and B-cell associated protein X (Bax) in the kidneys of high fat diet (HFD) obese rats.

METHODS

Thirty-six male Sprague Dawley rats were used. Control: received rat diet and water (1 mL/kg); HFD group: received HFD and water (1 mL/kg): bee bread (BB) preventive or orlistat preventive: received HFD and BB (0.5 g/kg) or HFD and orlistat (10 mg/kg); BB or orlistat treatment: received BB (0.5 g/kg) or orlistat (10 mg/kg).

RESULTS

HFD group had increased body weight, Body Mass Index, Lee Obesity Indices, kidney weights, malondialdehyde, inflammatory markers, Bax; decreased glutathione peroxidase, glutathione-S-transferase, superoxide dismutase, total antioxidant activity, no differences (p > .05) in food intakes, serum creatinine, sodium, potassium, chloride, catalase compared to control.

CONCLUSION

BB modulated most of these parameters, as corroborated by histology.

Bee bread attenuates the progression of atherosclerosis by activating Nrf2/Keap1 and modulating TNF-α/NF-κβ-associated mast cell migration and a mitochondrial-dependent apoptotic pathway in the obese rat model

This study explores the anti-atherosclerotic effects of bee bread in the context of oxidative stress, inflammation, and apoptosis phenomena in an obesity animal model, and its vitamin composition. Forty male Sprague-Dawley rats were administered with a normal diet (Normal group) and a high-fat diet (HFD) to induce obesity. After 6 weeks, obese rats that received the HFD were treated either with distilled water (Ob group), bee bread at 0.5 g per kg per day (Ob + Bb group), or orlistat at 10 mg per kg per day (Ob + Or group) concomitant with the HFD for another 6 weeks. Bee bread significantly improved atherosclerotic changes by enhancing the immunoexpressions of Nrf2/Keap1, impeding the immunoexpressions of NF-κβ downstream proteins, and intensifying Bcl-2 upregulation, attributed to the improvement in mast cell adherence and collagen deposition in the aortic wall of the Ob + Bb group. We have demonstrated that the treatment with bee bread attenuates the progression of atherosclerosis through its inhibition of vascular oxidative stress, and retardation of inflammatory reaction and apoptosis in obese rats, indicating its potential therapeutic targets for obesity-related vascular diseases. This could be partly attributed to the components of vitamins such as vitamins A, C and E that are present in bee bread, which need further study for the exact molecular mechanism of action.

Protective effect of saxagliptin against renal ischaemia reperfusion injury in rats

Saxagliptin is an effective and selective dipeptidyl peptidase-4 (DPP-4) inhibitor. This study was designed to determine possible protective effects of saxagliptin against damage caused by renal ischaemia/reperfusion (I/R) in rats. In this study, 40 rats were divided into 4 groups (n = 10 for each). Group 1 (Control), Group 2 (I/R) in both kidneys ischaemia of 45 min was performed, and then reperfusion was applied for 24 h. Saxagliptin (Group 3: 2 mg/kg and Group 4: 10 mg/kg) was administered by oral gavage to the animals in treatment groups, before the I/R. Saxagliptin decreased the markers (BUN, Cre, NGAL, KIM-1 and IL-18) of acute renal damage in blood and kidney tissue. Saxagliptin provided increase in antioxidant enzyme levels and decrease in MDA and apoptosis. Histological results showed that the administration of saxagliptin exhibited a protective effect against renal damage caused by I/R. These results indicates that saxagliptin provide protection against kidney injury caused by I/R.

Oxidative Stress and Ischemia/Reperfusion Injury in Kidney Transplantation: Focus on Ferroptosis, Mitophagy and New Antioxidants

Although there has been technical and pharmacological progress in kidney transplant medicine, some patients may experience acute post-transplant complications. Among the mechanisms involved in these conditions, ischemia/reperfusion (I/R) injury may have a primary pathophysiological role since it is one of the leading causes of delayed graft function (DGF), a slow recovery of the renal function with the need for dialysis (generally during the first week after transplantation). DGF has a significant social and economic impact as it is associated with prolonged hospitalization and the development of severe complications (including acute rejection). During I/R injury, oxidative stress plays a major role activating several pathways including ferroptosis, an iron-driven cell death characterized by iron accumulation and excessive lipid peroxidation, and mitophagy, a selective degradation of damaged mitochondria by autophagy. Ferroptosis may contribute to the renal damage, while mitophagy can have a protective role by reducing the release of reactive oxygen species from dysfunctional mitochondria. Deep comprehension of both pathways may offer the possibility of identifying new early diagnostic noninvasive biomarkers of DGF and introducing new clinically employable pharmacological strategies. In this review we summarize all relevant knowledge in this field and discuss current antioxidant pharmacological strategies that could represent, in the next future, potential treatments for I/R injury.

Fucoxanthin Attenuates Oxidative Damage by Activating the Sirt1/Nrf2/HO-1 Signaling Pathway to Protect the Kidney from Ischemia-Reperfusion Injury

Oxidative stress is a key component of renal ischemia/reperfusion (I/R) injury. Fucoxanthin (Fx), a marine carotenoid with enhanced antioxidant capacity, acts as a ROS inhibitor in diseases such as ischemic stroke and acute lung injury. We hypothesized that fucoxanthin could attenuate renal I/R-induced oxidative damage. C57BL/6 mice ( $n=30$ ) were randomly assigned to sham, IR, $\text{IR}+\text{DMSO}$ , and $\text{IR}+\text{Fx}$ (25, 50, and 100 mg/kg) groups. The renal I/R injury was induced by clamping the left kidney nephron tip in mice. Fucoxanthin was injected intraperitoneally 24 hours before surgery. Compared with the IR group, pretreatment with fucoxanthin significantly improved renal dysfunction and tissue structural damage and inhibited ROS levels and apoptosis. Consistent results were observed in HK-2 cells. Besides, we found that renal I/R resulted in decreased expression of Sirt1, Nrf2, and HO-1, while fucoxanthin upregulated the expression of Sirt1, Nrf2, and HO-1. The protective effects of fucoxanthin were significantly reversed by EX527 (a selective inhibitor of Sirt1) or si-Sirt1. In conclusion, our study investigated the protective effect of fucoxanthin against renal I/R injury, and the underlying mechanism may be related to the activation of the Sirt1/Nrf2/HO-1 signaling pathway by fucoxanthin to attenuate oxidative stress-induced apoptosis.

Hepatoprotective Effect of Bee Bread in Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) Rats: Impact on Oxidative Stress and Inflammation

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a pathological accumulation of hepatic lipid closely linked with many metabolic disorders, oxidative stress and inflammation. We aimed to evaluate the hepatoprotective effect of bee bread on oxidative stress and inflammatory parameters in MAFLD rats. Twenty-eight male Sprague-Dawley rats were assigned into four groups (n = 7/group): normal control (NC), high-fat diet (HFD), bee bread (HFD + Bb, HFD + 0.5 g/kg/day bee bread) and orlistat (HFD + Or, HFD + 10 mg/kg/day orlistat) groups. After 12 weeks, the HFD group demonstrated significantly higher body weight gain, serum levels of lipids (TG, TC, LDL), liver enzymes (AST, ALT, ALP) and adiponectin, liver lipids (TG, TC) and insulin resistance (HOMA-IR). Furthermore, the HFD group showed significantly decreased antioxidant enzyme activities (GPx, GST, GR, SOD, CAT) and GSH level, and increased liver oxidative stress (TBARS, NO), translocation of Nrf2 to the nucleus, Keap1 expression and inflammation (TNF-α, NF-κβ, MCP-1) together with histopathological alterations (steatosis, hepatocyte hypertrophy, inflammatory cell infiltration, collagen deposition), which indicated the presence of non-alcoholic steatohepatitis (NASH) and fibrosis. Bee bread significantly attenuated all these changes exerted by HFD feeding. In conclusion, our results suggest that bee bread might have antioxidant, anti-inflammatory, anti-steatotic and anti-fibrotic effects that are beneficial in protecting liver progression towards NASH and fibrosis.

Protective and Therapeutic Effects of Orlistat on Metabolic Syndrome and Oxidative Stress in High-Fat Diet-Induced Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) in Rats: Role on Nrf2 Activation

Metabolic dysfunction-associated fatty liver disease (MAFLD) is an excessive buildup of liver lipids closely associated with various kinds of undesirable metabolic effects and oxidative stress. We aimed to investigate the protective and therapeutic effects of orlistat on metabolic syndrome and oxidative stress parameters in high-fat diet (HFD) induced-MAFLD rats. Twenty-four male Sprague-Dawley rats were randomly divided into four groups (n = 6/group), i.e., Normal control (N), HFD, HFD + orlistat (HFD + O) (10 mg/kg/day administered concomitantly for 12 weeks as a protective model), and obese+orlistat (OB + O) (10 mg/kg/day administered 6 weeks after induction of obesity as a therapeutic model) groups. After 12 weeks, the HFD group had significantly increased Lee obesity index, serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total cholesterol, triglyceride, low-density lipoprotein levels, liver total cholesterol and triglyceride levels, insulin resistance and non-alcoholic steatohepatitis (NASH) together with decreased serum high-density lipoprotein level. Additionally, the HFD group also showed increased Nrf2 translocation to the nucleus with high Keap1 expression and increased liver oxidative stress parameters. Orlistat significantly improved all these alterations in HFD rats. We demonstrated that orlistat might have protective and therapeutic effects against HFD-induced MAFLD rats by its activation on Nrf2 signaling pathway, which subsequently improved metabolic syndrome and oxidative stress parameters.

DHA-rich fish oil and Tualang honey reduce chronic stress-induced oxidative damage in the brain of rat model

Background

Exposure to chronic stress induces oxidative damage which alters the dynamic balance between antioxidant and pro-oxidant activities in the brain. Tualang honey (TH) is a Malaysian wild multifloral honey which has been shown to contain high amount antioxidants. DHA-rich fish oil is a form of omega-3 fatty acids found in fish which also possesses some antioxidant activity. This study aimed to evaluate anti-stress activity of DHA-rich fish oil, TH and their combination on several parameters of oxidative stress in chronic stress rat model.

Methods

Fifty male Sprague Dawley rats were divided into (i) control, (ii) stress-exposed, (iii) stress-exposed and treated with TH (1 g/kg body weight twice daily), (iv) stress-exposed and treated with DHA-rich fish oil (450 mg/kg body weight twice daily), and (v) stress-exposed and treated with a combination of TH and DHA-rich fish oil. The chronic stress regimen consisted of a combination of restraint stress and a swim stress test for 28 days.

Results

DHA-rich fish oil and TH significantly (p < 0.05) supressed stress-induced elevation of serum corticosterone and lipid peroxidation, and caused a significant increase in total antioxidant capacity. For glutathione status, only TH significantly reduced stress-induced elevation of oxidised glutathione (GSSG) and normalised GSH/GSSG ratio. Conclusion: Both DHA-rich fish oil and TH have protective effects against brain oxidative stress but consuming these substances together does not seem to provide an additional benefit compared to consuming them separately.

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Investigated the effect of honey, DHA and their combination in single experimental setting.

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Tualang honey and DHA-rich fish oil can attenuate brain oxidative stress in chronic stress rat model.

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Combination of Tualang honey and DHA -rich fish oil is not superior than consuming these substances separately.

Perilipin 2 Impacts Acute Kidney Injury via Regulation of PPARα

Renal ischemia-reperfusion (I/R) can induce oxidative stress and injury via the generation of reactive oxygen species (ROS). Renal proximal tubular cells are susceptible to oxidative stress, and the dysregulation of renal proximal tubular cellular homeostasis can damage cells via apoptotic pathways. A recent study showed that the generation of ROS can increase perilipin 2 (Plin2) expression in HepG2 cells. Some evidence has also demonstrated the association between Plin2 expression and renal tumors. However, the underlying mechanism of Plin2 in I/R-induced acute kidney injury (AKI) remains elusive. Here, using a mouse model of I/R-induced AKI, we found that ROS generation was increased and the expression of Plin2 was significantly upregulated. An in vitro study further revealed that the expression of Plin2, and the generation of ROS were significantly upregulated in primary tubular cells treated with hydrogen peroxide. Accordingly, Plin2 knockdown decreased apoptosis in renal proximal tubular epithelial cells treated with hydrogen peroxide, which depended on the activation of peroxisome proliferator-activated receptor α (PPARα). Overall, the present study demonstrated that Plin2 is involved in AKI; knockdown of this marker might limit apoptosis via the activation of PPARα. Consequently, the downregulation of Plin2 could be a novel therapeutic strategy for AKI.

Bee bread mitigates downregulation of steroidogenic genes, decreased spermatogenesis, and epididymal oxidative stress in male rats fed with high-fat diet

The pituitary-gonadal axis plays an important role in steroidogenesis and spermatogenesis, and by extension, fertility. The aim of this study was to investigate the protective role of bee bread, a natural bee product, against obesity-induced decreases in steroidogenesis and spermatogenesis. Thirty-two adult male Sprague-Dawley rats weighing between 200 and 300 g were divided into four groups (n = 8/group), namely: normal control (NC), high-fat diet (HFD), HFD plus bee bread administered concurrently for 12 wk (HFD + B), HFD plus orlistat administered concurrently for 12 wk (HFD + O) groups. Bee bread (0.5 g/kg) or orlistat (10 mg/kg/day) was suspended in distilled water and given by oral gavage daily for 12 wk. Levels of follicle-stimulating hormone, luteinizing hormone, testosterone, and adiponectin, as well as sperm count, motility, viability, normal morphology, and epididymal antioxidants decreased, whereas levels of leptin, malondialdehyde, and sperm nDNA fragmentation increased significantly in the HFD group relative to the NC group. There were significant decreases in the testicular mRNA transcript levels of androgen receptor, luteinizing hormone receptor, steroidogenic acute regulatory protein, cytochrome P450 enzyme, 3β-hydroxysteroid dehydrogenase (HSD) and 17β-HSD in the testes of the HFD group. Furthermore, mount, intromission and ejaculatory latencies increased, and penile cGMP level decreased significantly in the HFD group. Supplementation with bee bread significantly reduced leptin level and increased adiponectin level, enhanced sperm parameters and reduced sperm nDNA fragmentation, upregulated the levels of steroidogenic genes and proteins in HFD-induced obese male rats. Bee bread improved steroidogenesis and spermatogenesis by upregulating steroidogenic genes. Therefore, bee bread may be considered as a potential supplementation to protect against infertility in overweight men or men with obesity.NEW & NOTEWORTHY The high-fat diet utilized in the present study induced obesity in the male rats. Bee bread supplementation mitigated impaired steroidogenesis, spermatogenesis, mating behavior, and fertility potential by counteracting the downregulation of steroidogenic genes, thus increasing testosterone levels and suppressing epididymal oxidative stress. These benefits may be due to the abundance of phenolic and flavonoid compounds in bee bread.

Synthesis, Characterization, and Specific Localization of Mitochondrial-Targeted Antioxidant Peptide SS31 Probe

The aim of this study is to investigate the targeting efficiency of FITC-SS31 to mitochondria in both normal and H2O2-induced oxidative damaged 661W cells, characterizing the properties of FITC-SS31 in the biological assays. The purity and molecular weight of FITC-SS31 were identified using HPLC and MS. MTT and LDH assays were used to evaluate the cytotoxicity and cell permeability. The binding ability of FITC-SS31 to cells was demonstrated by flow cytometry. The colocalization of FITC-SS31 and MitoTracker both in normal and oxidative cells was analyzed by a laser confocal microscope. We detected the DEGs between SS31+H2O2 and H2O2-alone-treated cells by RNA seq. GO and KEGG analyses were performed to predict the functional gene of SS31. The molecular weight of FITC-SS31 was 1142.2 with the 97.76% purity. The flow cytometry results showed that the MFI (mean fluorescence intensity) of FITC-SS31 in normal cells in the 4 h probe treatment group was higher than that in the 2 h and the 0 h group. The MFI in the 2 h probe treatment group was much higher than that in the 4 h and 0 h groups in damaged cells. The positive rate of 10 μM FITC-SS31 was higher than that of 1 μM and 5 μM. Fluorescein imaging analysis confirmed that FITC-SS31 was overlapped with MitoTracker. Through the analysis, DEGs were highly expressed in "localization, organelle, antioxidant activity, binding" functions and enriched in "AMPK signaling pathway, MAPK targets/nuclear events mediated by MAP kinase pathway and PI3K-Akt signaling pathway." It is speculated that SS31 exerts an antioxidant effect through one of these pathways. We hypothesized that SS31 could play a more efficient role in the pathological cells in the half-life period to avoid cell death due to oxidative damage. The functions of the DEGs in SS31+H2O2 and H2O2-alone samples are related to the localization and antioxidant activity of SS31. DEGs are mostly enriched in the AMPK signaling pathway, which needs further studies.

Downregulation of XBP1 protects kidney against ischemia-reperfusion injury via suppressing HRD1-mediated NRF2 ubiquitylation

Ischemia-reperfusion (IR) injury to the renal epithelia is associated with endoplasmic reticulum stress (ERS) and mitochondria dysfunction, which lead to oxidative stress-induced acute kidney injury (AKI). X-box binding protein 1 (XBP1), an ERS response protein, could play a prominent role in IR-induced AKI. In this study, we revealed that XBP1 and its downstream target HRD1 participated in the crosstalk between ERS and mitochondrial dysfunction via regulation of NRF2/HO-1-mediated reactive oxidative stress (ROS) signaling. Mice with reduced expression of XBP1 (heterozygous Xbp1±) were resistant to IR-induced AKI due to the enhanced expression of NRF2/HO-1 and diminished ROS in the kidney. Downregulation of XBP1 in renal epithelial cells resulted in reduced HRD1 expression and increased NRF2/HO-1 function, accompanied with enhanced antioxidant response. Furthermore, HRD1 served as an E3-ligase to facilitate the downregulation of NRF2 through ubiquitination-degradation pathway, and the QSLVPDI motif on NRF2 constituted an active site for its interaction with HRD1. Thus, our findings unveil an important physiological role for XBP1/HRD1 in modulating the antioxidant function of NRF2/HO-1 in the kidney under stress conditions. Molecular therapeutic approaches that target XBP1-HRD1-NRF2 pathway may represent potential effective means to treat renal IR injury.

Restoration of afferent arteriolar autoregulatory behavior in ischemia-reperfusion injury in rat kidneys

Renal autoregulation is critical in maintaining stable renal blood flow (RBF) and glomerular filtration rate (GFR). Renal ischemia-reperfusion (IR)-induced kidney injury is characterized by reduced RBF and GFR. The mechanisms contributing to renal microvascular dysfunction in IR have not been fully determined. We hypothesized that increased reactive oxygen species (ROS) contributed to impaired renal autoregulatory capability in IR rats. Afferent arteriolar autoregulatory behavior was assessed using the blood-perfused juxtamedullary nephron preparation. IR was induced by 60 min of bilateral renal artery occlusion followed by 24 h of reperfusion. Afferent arterioles from sham rats exhibited normal autoregulatory behavior. Stepwise increases in perfusion pressure caused pressure-dependent vasoconstriction to 65 ± 3% of baseline diameter (13.2 ± 0.4 μm) at 170 mmHg. In contrast, pressure-mediated vasoconstriction was markedly attenuated in IR rats. Baseline diameter averaged 11.7 ± 0.5 µm and remained between 90% and 101% of baseline over 65-170 mmHg, indicating impaired autoregulatory function. Acute antioxidant administration (tempol or apocynin) to IR kidneys for 20 min increased baseline diameter and improved autoregulatory capability, such that the pressure-diameter profiles were indistinguishable from those of sham kidneys. Furthermore, the addition of polyethylene glycol superoxide dismutase or polyethylene glycol-catalase to the perfusate blood also restored afferent arteriolar autoregulatory responsiveness in IR rats, indicating the involvement of superoxide and/or hydrogen peroxide. IR elevated mRNA expression of NADPH oxidase subunits and monocyte chemoattractant protein-1 in renal tissue homogenates, and this was prevented by tempol pretreatment. These results suggest that ROS accumulation, likely involving superoxide and/or hydrogen peroxide, impairs renal autoregulation in IR rats in a reversible fashion.NEW & NOTEWORTHY Renal ischemia-reperfusion (IR) leads to renal microvascular dysfunction manifested by impaired afferent arteriolar autoregulatory efficiency. Acute administration of scavengers of reactive oxygen species, polyethylene glycol-superoxide dismutase, or polyethylene glycol-catalase following renal IR restored afferent arteriolar autoregulatory capability in IR rats, indicating that renal IR led to reversible impairment of afferent arteriolar autoregulatory capability. Intervention with antioxidant treatment following IR may improve outcomes in patients by preserving renovascular autoregulatory function and potentially preventing the progression to chronic kidney disease after acute kidney injury.

Anti-Atherogenic Effects of Orlistat on Obesity-Induced Vascular Oxidative Stress Rat Model

Obesity is typically linked to oxidative stress and inflammation, which lead to vascular damage and initiate the progression of atherosclerosis. The aim of this study was to determine the anti-atherosclerotic effect of orlistat on obesity-induced vascular oxidative stress in obese male rats. Twenty-four male Sprague-Dawley rats were categorized into two groups: normal (Normal group, n = 6) and high-fat diet (HFD group, n = 12). After six weeks, obese rats in the HFD group were administered either with distilled water (OB group) or orlistat 10 mg/kg/day (OB/OR group) for another six weeks. The OB group had a significant increase in lipid profiles (total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL)) and decrease in high-density lipoprotein (HDL) level compared to the Normal group. The aortic antioxidants enzymes activities (superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), and catalase (CAT)) as well as total glutathione (GSH) and total antioxidant capacity (TAC) of the OB group were significantly decreased compared to the Normal group. Furthermore, pro-inflammatory atherosclerotic markers (tumour necrosis factor-alpha (TNF-ɑ), vascular cell adhesion molecule-1 (VCAM-1), and intercellular cell adhesion molecule-1 (ICAM-1)) expressions were increased significantly, and anti-inflammatory marker (interleukin-10 (IL-10)) was decreased significantly in the OB group compared to the Normal group. Treatment with orlistat significantly improved lipid profile, increased antioxidant enzymes and expression of anti-inflammatory markers, and decreased the expression of the pro-inflammatory marker compared to the OB group. These findings may suggest the therapeutic effect of orlistat in attenuating the progression of the atherosclerotic stage in obesity.

Effect of bee bread on some biochemical parameters and skeletal muscle histology of high-fat diet-induced obese Sprague-Dawley rats

The effect of bee bread (BB) on the biochemical parameters-body weights, calorie intake, Lee obesity indices, serum amylase, aspartate and alanine amino transferases, skeletal muscle activities of creatine kinase, superoxide dismutase, glutathione peroxidase, catalase, malondialdehyde, glutathione-S-transferase, total antioxidant activity, endogenous secretory receptor for advanced glycation end products (esRAGE), and muscle histology of high-fat diet (HFD) obese rats-was studied. Thirty-six male Sprague-Dawley rats were divided into six groups: Control: received rat feed and water (1 ml/kg); HFD: received HFD and water (1 ml/kg): BB or orlistat preventive: received HFD and BB (0.5 g/kg) or HFD and orlistat (10 mg/kg; weeks 1 to 12); BB or orlistat treated: received HFD and BB (0.5 g/kg) or HFD and orlistat (10 mg/kg; weeks 6 to 12), following obesity induction. At week 12, HFD group had altered (p < .05) levels of some biochemical parameters which were modulated by BB and corroborated by muscle histology. PRACTICAL APPLICATIONS: Obesity is a global health problem, which prevalence has continued to be on the increase due to changes in lifestyle and dietary behavior. Additionally, the approaches that currently are being used for the treatment of this disease have not been able to successfully reverse obesity and its associated complications. The current study which showed that bee bread prevented or attenuated obesity-induced muscular pathology, places bee bread in the spotlight as a functional food that could be useful in preventing or mitigating obesity-induced muscular pathology.

Catalytic Antioxidants in the Kidney

Reactive oxygen species and reactive nitrogen species are highly implicated in kidney injuries that include acute kidney injury, chronic kidney disease, hypertensive nephropathy, and diabetic nephropathy. Therefore, antioxidant agents are promising therapeutic strategies for kidney diseases. Catalytic antioxidants are defined as small molecular mimics of antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase, and some of them function as potent detoxifiers of lipid peroxides and peroxynitrite. Several catalytic antioxidants have been demonstrated to be effective in a variety of in vitro and in vivo disease models that are associated with oxidative stress, including kidney diseases. This review summarizes the evidence for the role of antioxidant enzymes in kidney diseases, the classifications of catalytic antioxidants, and their current applications to kidney diseases.

Effect of Tempol, a Membrane-Permeable Free Radical Scavenger, on In Vitro Model of Eye Inflammation on Rabbit Corneal Cells

Purpose: Inflammatory corneal diseases such as bacterial keratitis provoke severe injury to the visual functions and physical structure, leading to opaqueness, wounding, damage to the cornea, and even long-lasting vision loss. Usually antioxidant substances have been of great attention as candidate therapies in the management of keratitis in both humans and animals. Based on the findings, the aim of our research was to examine the effects of Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a membrane-permeable free radical scavenger with exclusive antioxidant properties, on in vitro model of eye inflammation of rabbit corneal cells stimulated with lipopolysaccharide (LPS) (Seruminstitute Rabbit Cornea). Methods: The cells were pretreated with Tempol and incubated with LPS for 24 h. LPS stimulation triggered increased cellular mortality, oxidative stress, cytokine levels expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, and also enhanced prostaglandin E₂ (PGE₂) levels and cyclooxygenase-2 (COX-2) expression. Results: Pretreatment with Tempol (3 mM) significantly increased cell viability and antioxidant activity as well as decreased reactive oxygen species production, cytokines, PGE₂ levels, and COX-2 expression. Conclusions: Taken together, Tempol could be a new therapeutic strategy for management of ocular inflammatory disorders for clinical and veterinary use.

Reactive oxygen species in renal vascular function

Reactive oxygen species (ROS) are produced by the aerobic metabolism. The imbalance between production of ROS and antioxidant defence in any cell compartment is associated with cell damage and may play an important role in the pathogenesis of renal disease. NADPH oxidase (NOX) family is the major ROS source in the vasculature and modulates renal perfusion. Upregulation of Ang II and adenosine activates NOX via AT1R and A1R in renal microvessels, leading to superoxide production. Oxidative stress in the kidney prompts renal vascular remodelling and increases preglomerular resistance. These are key elements in hypertension, acute and chronic kidney injury, as well as diabetic nephropathy. Renal afferent arterioles (Af), the primary resistance vessel in the kidney, fine tune renal hemodynamics and impact on blood pressure. Vice versa, ROS increase hypertension and diabetes, resulting in upregulation of Af vasoconstriction, enhancement of myogenic responses and change of tubuloglomerular feedback (TGF), which further promotes hypertension and diabetic nephropathy. In the following, we highlight oxidative stress in the function and dysfunction of renal hemodynamics. The renal microcirculatory alterations brought about by ROS importantly contribute to the pathophysiology of kidney injury, hypertension and diabetes.

Perivascular adipose tissue phenotype and sepsis vascular dysfunction: Differential contribution of NO, ROS and beta 3-adrenergic receptor

AIMS

Vascular dysfunction plays a key role in sepsis but the role of perivascular adipose tissue (PVAT) in this condition is relatively unknown.

MAIN METHODS

Sepsis was induced by cecal ligation and puncture (CLP). The responses of the aorta and superior mesenteric artery to norepinephrine in the presence or absence of PVAT were evaluated. Fluorescent probes measured the production of nitric oxide (NO) and reactive oxygen species (ROS). NO synthases (NOS) and β3-adrenoceptor expression were detected by immunofluorescence and S-nitrosylation by the biotin switch assay.

KEY FINDINGS

Aorta and superior mesenteric arteries from septic animals with intact PVAT showed a worsened response to the vasoconstrictor compared to vessels without PVAT. PVAT from the aorta (APVAT) produced NO and ROS whereas PVAT from the superior mesenteric artery (MPVAT) produced only ROS. Septic APVAT exhibited a higher density of NOS-1 and NOS-3. S-nitrosylation was found in APVAT. Donor (PVAT obtained from normal or septic rats):Host (normal vessel without PVAT) experiments showed that L-NAME, ODQ and β3-adrenergic receptor antagonist blocked the septic APVAT anti-contractile effect. None of these compounds affected MPVAT; tempol, but not apocynin, blocked its anti-contractile effect.

SIGNIFICANCE

PVAT contributes to the anti-contractile effect in the aorta and mesenteric artery of septic rats through different pathways. β3-Adrenergic receptor and NO appear to be key mediators of this effect in APVAT, but not in MPVAT where ROS seem to be a relevant mediator. Therefore, PVAT is a relevant player of sepsis vascular dysfunction.

Notoginsenoside R1 Suppresses Inflammatory Signaling and Rescues Renal Ischemia-Reperfusion Injury in Experimental Rats

Background

Notoginsenoside R1 (NR) is a major dynamic constituent of Panax notoginseng found to possess anti-inflammatory activity against various inflammatory diseases. However, its protective effects against renal ischemia-reperfusion (I/R) injury have not been elucidated. In male Wistar rats, we induced I/R under general anesthesia by occluding the renal artery for 60 min, followed by reperfusion and right nephrectomy.

Material/Methods

Rats were randomized to 4 groups: a sham group, an I/R group, an NR-pretreated (50 mg/kg) before I/R induction group, and an NR control group. All animals were killed at 72 h after I/R induction. Blood and renal tissues were collected, and histological and basic renal function parameters were assessed. In addition, levels of various kidney markers and proinflammatory cytokines were measured using RT-PCR, ELISA, and immunohistochemistry analysis.

Results

After I/R induction, the onset of renal dysfunction was shown by the elevated levels of serum urea, creatinine levels, and histological evaluation, showing a 2-fold increase in the renal failure markers kim-1 and NGAL compared to control rats. Rats pretreated with NR before I/R induction had significantly better renal functions, with attenuated levels of oxidative markers, restored levels of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), tumor growth factor-β1 (TGF-β1), INF-γ, and IL-6, and increased anti-inflammatory cytokine levels (IL-10) compared to I/R-induced rats.

Conclusions

NR suppressed I/R-induced inflammatory cytokines production by suppressing oxidative stress and kidney markers, suggesting that NR is a promising drug candidate for prevention, progression, and treatment of renal dysfunction.

Novel Fluorescent Mitochondria-Targeted Probe MitoCLox Reports Lipid Peroxidation in Response to Oxidative Stress In Vivo

A new mitochondria-targeted probe MitoCLox was designed as a starting compound for a series of probes sensitive to cardiolipin (CL) peroxidation. Fluorescence microscopy reported selective accumulation of MitoCLox in mitochondria of diverse living cell cultures and its oxidation under stress conditions, particularly those known to cause a selective cardiolipin oxidation. Ratiometric fluorescence measurements using flow cytometry showed a remarkable dependence of the MitoCLox dynamic range on the oxidation of the sample. Specifically, MitoCLox oxidation was induced by low doses of hydrogen peroxide or organic hydroperoxide. The mitochondria-targeted antioxidant 10-(6'-plastoquinonyl)decyltriphenyl-phosphonium (SkQ1), which was shown earlier to selectively protect cardiolipin from oxidation, prevented hydrogen peroxide-induced MitoCLox oxidation in the cells. Concurrent tracing of MitoCLox oxidation and membrane potential changes in response to hydrogen peroxide addition showed that the oxidation of MitoCLox started without a delay and was complete during the first hour, whereas the membrane potential started to decay after 40 minutes of incubation. Hence, MitoCLox could be used for splitting the cell response to oxidative stress into separate steps. Application of MitoCLox revealed heterogeneity of the mitochondrial population; in living endothelial cells, a fraction of small, rounded mitochondria with an increased level of lipid peroxidation were detected near the nucleus. In addition, the MitoCLox staining revealed a specific fraction of cells with an increased level of oxidized lipids also in the culture of human myoblasts. The fraction of such cells increased in high-density cultures. These specific conditions correspond to the initiation of spontaneous myogenesis in vitro, which indicates that oxidation may precede the onset of myogenic differentiation. These data point to a possible participation of oxidized CL in cell signalling and differentiation.

Inhibition of Disruptor of Telomeric Silencing 1-Like Alleviated Renal Ischemia and Reperfusion Injury-Induced Fibrosis by Blocking PI3K/AKT-Mediated Oxidative Stress

Background

Ischemia/reperfusion (I/R) injury is a major cause of acute kidney injury, usually occurs during renal surgeries, and may eventually lead to chronic kidney diseases. However, effective therapeutic targets for renal I/R injury remain limited.

Purpose

In the present study, we investigated whether inhibition of disruptor of telomeric silencing 1-like (Dot1l) could alleviate renal I/R in vivo and in vitro, as well as the potential mechanisms involved in this process.

Methods

Sprague–Dawley rats were subjected to right renal ischemia for 45 mins and reperfusion for 0, 7, or 14 days with and without the Dot1l inhibitor EPZ004777. In addition, human renal proximal tubular epithelial cell line human kidney-2 cells were subjected to the hypoxia/reoxygenation (H/R) process (ie, 3 hrs hypoxia, 12 hrs and 24 hrs reoxygenation), with or without Dot1l inhibitor or genetic knockdown.

Results

Inhibition of Dot1l through EPZ004777 or genetic knockdown reduced the expression of alpha-smooth muscle actin, vimentin, and fibronectin in I/R- and H/R-induced injury. Moreover, H/R-induced fibrosis depended on oxidative stress in vitro. In addition, I/R- and H/R-induced generation of reactive oxygen species (ROS) was attenuated by EPZ004777 or small interfering RNA for Dot1l. Furthermore, the elevation of ROS induced by Dot1l was regulated via phosphatidylinositol 3-kinase (PI3K) and serine-threonine protein kinase (AKT) phosphorylation in vivo and in vitro.

Conclusion

Inhibition of Dot1l alleviated renal fibrosis by preventing the generation of ROS via the PI3K/AKT pathway. These results indicate that inhibitor of Dot1l could be a potential therapeutic target for renal I/R injury.

Angiotensin II-induced superoxide and decreased glutathione in proximal tubules: effect of dietary fructose

Angiotensin II exacerbates oxidative stress in part by increasing superoxide (O2-) production by many renal tissues. However, whether it does so in proximal tubules and the source of O2- in this segment are unknown. Dietary fructose enhances the stimulatory effect of angiotensin II on proximal tubule Na⁺ reabsorption, but whether this is true for oxidative stress is unknown. We hypothesized that angiotensin II causes proximal nephron oxidative stress in part by stimulating NADPH oxidase (NOX)4-dependent O2- production and decreasing the amount of the antioxidant glutathione, and this is exacerbated by dietary fructose. We measured basal and angiotensin II-stimulated O2- production with and without inhibitors, NOX1 and NOX4 expression, and total and reduced glutathione (GSH) in proximal tubules from rats drinking either tap water (control) or 20% fructose. Angiotensin II (10 nM) increased O2- production by 113 ± 42 relative light units·mg protein^-1·s^-1 in controls and 401 ± 74 relative light units·mg protein^-1·s^-1 with 20% fructose (n = 11 for each group, P < 0.05 vs. control). Apocynin and the Nox1/4 inhibitor GKT136901 prevented angiotensin II-induced increases in both groups. NOX4 expression was not different between groups. NOX1 expression was undetectable. Angiotensin II decreased GSH by 1.8 ± 0.8 nmol/mg protein in controls and by 4.2 ± 0.9 nmol/mg protein with 20% fructose (n = 18 for each group, P < 0.047 vs. control). We conclude that 1) angiotensin II causes oxidative stress in proximal tubules by increasing O2- production by NOX4 and decreasing GSH and 2) dietary fructose enhances the ability of angiotensin II to stimulate O2- and diminish GSH, thereby exacerbating oxidative stress in this segment.

Oxidative stress as a potential target in acute kidney injury

Background

Acute kidney injury (AKI) is a major problem for health systems being directly related to short and long-term morbidity and mortality. In the last years, the incidence of AKI has been increasing. AKI and chronic kidney disease (CKD) are closely interconnected, with a growing rate of CKD linked to repeated and severe episodes of AKI. AKI and CKD can occur also secondary to imbalanced oxidative stress (OS) reactions, inflammation, and apoptosis. The kidney is particularly sensitive to OS. OS is known as a crucial pathogenetic factor in cellular damage, with a direct role in initiation, development, and progression of AKI. The aim of this review is to focus on the pathogenetic role of OS in AKI in order to gain a better understanding. We exposed the potential relationships between OS and the perturbation of renal function and we also presented the redox-dependent factors that can contribute to early kidney injury. In the last decades, promising advances have been made in understanding the pathophysiology of AKI and its consequences, but more studies are needed in order to develop new therapies that can address OS and oxidative damage in early stages of AKI.

Methods

We searched PubMed for relevant articles published up to May 2019. In this review we incorporated data from different types of studies, including observational and experimental, both in vivo and in vitro, studies that provided information about OS in the pathophysiology of AKI.

Results

The results show that OS plays a major key role in the initiation and development of AKI, providing the chance to find new targets that can be therapeutically addressed.

Discussion

Acute kidney injury represents a major health issue that is still not fully understood. Research in this area still provides new useful data that can help obtain a better management of the patient. OS represents a major focus point in many studies, and a better understanding of its implications in AKI might offer the chance to fight new therapeutic strategies.

Polystyrene Nanoparticles Reduced ROS and Inhibited Ferroptosis by Triggering Lysosome Stress and TFEB Nucleus Translocation in a Size-Dependent Manner

Though plastic nanoparticles have already raised much concern for their potential impact on health, our understanding of their biological effects is still utterly limited. Here we demonstrate for the first time that carboxyl-modified polystyrene nanoparticles (CPS) could effectively inhibit ferroptosis as a result of reduced cellular ROS which was triggered by transcription factor EB (TFEB) nucleus translocation. In this process, CPS first entered cells via macropinocytosis, then CPS-containing macropinosomes fused with lysosomes and expanded into abnormal lysosome-like large vacuoles in vacuolar-type H⁺-ATPase (V-ATPase) and aquaporins (AQPs) in a dependent way. These large vacuoles were detected both in vitro and in vivo, which was found to be a sign of lysosome stress. The lysosome stress induced deactivation of mammalian target of rapamycin (mTOR) which led to nucleus translocation of TFEB. Then, TFEB-dependent enhanced expression of lysosomal proteins and superoxide dismutase (SOD) which ultimately led to ROS reduction and inhibition of ferroptosis. Knockout of TFEB-enhanced ferroptosis was triggered by Erastin and abolished the effect of CPS on ROS and ferroptosis. In summary, our results reveal a novel mechanism whereby CPS reduced ROS and inhibited ferroptosis in a TFEB-dependent way. These findings have important implications for understanding the biological effects of polystyrene nanoparticles and searching for new anti-ROS and antiferroptosis particles or reagents.

Nitric oxide mediated the effects of nebivolol in cardiorenal syndrome

OBJECTIVES

Despite several proposed mechanisms for the pathophysiology of cardiorenal syndrome (CRS), the exact mechanism remains unclear. Nitrosative stress has been argued as a key mechanism recently. Nebivolol is a beta-blocker with nitric oxide (NO)-releasing effect. In the present study, NO-mediated effects of two different treatment regimes of nebivolol in CRS were studied.

MATERIALS AND METHODS

Rats were divided into: sham-operated (sham-control), myocardial infarction (MI)-induced, (MI-control) early nebivolol-treated (MI-neb1) and late nebivolol-treated (Mı-neb2) groups. The effects of nebivolol were assessed both in the early and late period of MI by histologic, hemodynamic and biologic studies.

RESULTS

Developed MI model was in line with the heart failure with preserved ejection fraction. Focal and total tubular damage findings were observed in MI-control group both in early and late period of MI. In parallel, subclinical functional damage was transformed into chronic renal dysfunction in this group. Increased inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS) together with decreased neuronal NOS (nNOS) levels were in parallel with the increased inflammation and nitrosative stress biomarkers. Nebivolol effectively prevented both subclinical and clinical nephropathy. There was no statistical difference between the nebivolol treatment regimes.

CONCLUSION

The beneficial effects of nebivolol were closely related to the reduction of nitrosative damages as well as hemodynamic alterations. The NO-mediated effects were: prevention of nitrosative damage by decreasing iNOS, preservation of nNOS in order to maintain glomerular filtration rate (GFR), and restoration of eNOS in the late period of MI. On contrary to our previous work, early nebivolol administration had a similar effect with delayed administration of nebivolol on CRS.

Uncoupling protein 1 inhibits mitochondrial reactive oxygen species generation and alleviates acute kidney injury

BACKGROUND

Uncoupling protein 1 (UCP1) is predominantly found in brown adipose tissue mitochondria, and mediates energy dissipation to generate heat rather than ATP via functional mitochondrial uncoupling. However, little is known about its expression and function in kidney.

METHODS

We carried out a mRNA microarray analysis in mice kidneys with ischemia reperfusion (IR) injury. The most dramatically downregulated gene UCP1 after IR was identified, and its role in generation of mitochondrial reactive oxygen species (ROS) and oxidative stress injury was assessed both in vitro and in vivo. Genetic deletion of UCP1 was used to investigate the effects of UCP1 on ischemia or cisplatin-indued acute kidney injury (AKI) in mice.

FINDINGS

UCP1 was located in renal tubular epithelial cells in kidney and downregulated in a time-dependent manner during renal IR. Deletion of UCP1 increased oxidative stress in kidneys and aggravated ischemia or cisplatin induced AKI in mice.Viral-based overexpression of UCP1 reduced mitochondrial ROS generation and apoptosis in hypoxia-treated tubular epithelial cells. Furthermore, UCP1 expression was regulated by peroxisome proliferator-activator receptor (PPAR) γ in kidneys during renal IR. Overexpression of PPAR-γ resembled UCP1-overexpression phenotype in vitro. Treatment with PPAR-γ agonist could induce UCP1 upregulation and provide protective effect against renal IR injury in UCP1^+/+mice, but not in UCP1^-/-mice.

INTERPRETATION

UCP1 protects against AKI likely by suppressing oxidative stress, and activation of UCP1 represents a potential therapeutic strategy for AKI. FUND: National Natural Science Foundation of China grants, Science and Technology Commission of Shanghai.

Anti-inflammatory role of tempol (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl) in nephroprotection

Inflammation is one of the mechanisms involved in the acute kidney injury (AKI) caused by cisplatin (CP)-induced nephrotoxicity. Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl) has powerful antioxidant activity. We investigated its potential nephroprotective effects and the underlying mechanisms that may add further benefits to its clinical usefulness in a CP-induced AKI model. Male Swiss albino mice were divided randomly into four groups: control, CP (20 mg/kg intraperitoneally), tempol (100 mg/kg/day, per os) + CP, and tempol only treatments. Blood samples were collected to analyze renal function parameters. Immunoblotting and immunohistochemical analysis were used to assess the level and localization of inflammatory markers. Tempol afforded protection to animals from CP-induced elevation of inflammatory markers as indicated by reduced expression of nuclear factor-kappa B, cyclooxygenase-2, and tumor necrosis factor-α in kidney tissue. Histological findings and analysis of kidney function markers corroborated with these findings confirming a nephroprotective role for tempol. In conclusion, this study provides important evidence for the promising anti-inflammatory effects of tempol which appears to contribute significantly to its nephroprotective action.

Targeted Treatments for Chronic Obstructive Pulmonary Disease (COPD) Using Low-Molecular-Weight Drugs (LMWDs)

Chronic obstructive pulmonary disease (COPD) is a very common and frequently fatal airway disease. Current therapies for COPD depend mainly on long-acting bronchodilators, which cannot target the pathogenic mechanisms of chronic inflammation in COPD. New pharmaceutical therapies for the inflammatory processes of COPD are urgently needed. Several anti-inflammatory targets have been identified based on increased understanding of the pathogenesis of COPD, which raises new hopes for targeted treatment of this fatal respiratory disease. In this review, we discuss the recent advances in bioactive low-molecular-weight drugs (LMWDs) for the treatment of COPD and, in addition to the first-line drug bronchodilators, focus particularly on low-molecular-weight anti-inflammatory agents, including modulators of inflammatory mediators, inflammasome inhibitors, protease inhibitors, antioxidants, PDE4 inhibitors, kinase inhibitors, and other agents. We also provide new insights into targeted COPD treatments using LMWDs, particularly small-molecule agents.