Reactive oxygen species and acute renal failure

Effects of Coatings on Antioxidant Enzyme Activities, Histopathology, and Transcriptome Profiles of Kidney Tissue in Larimichthys crocea

Background: As an innovative approach to deep-sea aquaculture, fish farm vessels offer a dual benefit by alleviating the pressure on offshore fishing resources while providing an additional high-quality protein source. However, the potential impacts of vessel coatings on farmed fish remain poorly understood. Methods: In this study, to investigate the effects of vessel coatings on the large yellow croaker (Larimichthys crocea), we established four experimental groups with coating concentrations at 1-fold, 10-fold, 20-fold, and 80-fold levels. Antioxidant enzyme activities in kidney tissues were measured across all groups, while histological and transcriptome analyses were specifically conducted for the 1-fold and 80-fold concentration groups. Results: Firstly, significant alterations in antioxidant enzyme activity were observed in the 80-fold concentration group. Moreover, histological analysis demonstrated more severe pathological changes in kidney tissue at the higher concentration, including interstitial hemorrhage and tubular epithelial cell fatty degeneration. In addition, we identified 11,902 differentially expressed genes (DEGs) by high-throughput sequencing. KEGG pathway enrichment analysis revealed that the DEGs were predominantly involved in critical biological processes, including endoplasmic reticulum protein processing, oxidative phosphorylation, cytokine-cytokine receptor interactions, cell cycle regulation, DNA replication, and PPAR signaling pathways. Finally, the validation of nine selected DEGs through quantitative real-time PCR (qRT-PCR) showed significant correlation with RNA-Seq data, confirming the reliability of our transcriptome analysis. Conclusions: This study provides preliminary insights into the antioxidant stress response mechanisms of L. crocea to coating exposure and establishes a theoretical foundation for optimizing healthy fish farming practices in aquaculture vessels.

Synthetic Bilirubin-Based Nanomedicine Protects Against Renal Ischemia/Reperfusion Injury Through Antioxidant and Immune-Modulating Activity

Renal ischemia/reperfusion injury (IRI) is a common form of acute kidney injury. The basic mechanism underlying renal IRI is acute inflammation, where oxidative stress plays an important role. Although bilirubin exhibits potent reactive oxygen species (ROS)-scavenging properties, its clinical application is hindered by problems associated with solubility, stability, and toxicity. In this study, BX-001N, a synthetic polyethylene glycol-conjugated bilirubin 3α nanoparticle is developed and assessed its renoprotective effects in renal IRI. Intravenous administration of BX-001N led to increase uptake in the kidneys with minimal migration to the brain after IRI. Peri-IRI BX-001N administration improves renal function and attenuates renal tissue injury and tubular apoptosis to a greater extent than free bilirubin on day 1 after IRI. BX-001N suppressed renal infiltration of inflammatory cells and reduced expression of TNF-α and MCP-1. Furthermore, BX-001N increases renal tubular regeneration on day 3 and suppresses renal fibrosis on day 28. BX-001N decreases the renal expressions of dihydroethidium, malondialdehyde, and nitrotyrosine after IRI. In conclusion, BX-001N, the first Good Manufacturing Practice-grade synthetic bilirubin-based nanomedicine attenuates acute renal injury and chronic fibrosis by suppressing ROS generation and inflammation after IRI. It shows adequate safety profiles and holds promise as a new therapy for renal IRI.

Effects of Cerium Oxide on Kidney and Liver Tissue Damage in an Experimental Myocardial Ischemia-Reperfusion Model of Distant Organ Damage

Background and Objectives: Ischemia-reperfusion (I/R) injury is a process in which impaired perfusion is restored by restoring blood flow and tissue recirculation. Nanomedicine uses cutting-edge technologies that emerge from interdisciplinary influences. In the literature, there are very few in vivo and in vitro studies on how cerium oxide (CeO2) affects systemic anti-inflammatory response and inflammation. Therefore, in our study, we aimed to investigate whether CeO2 administration has a protective effect against myocardial I/R injury in the liver and kidneys. Materials and Methods: Twenty-four rats were randomly divided into four groups after obtaining approval from an ethics committee. A control (group C), cerium oxide (group CO), IR (group IR), and Cerium oxide-IR (CO-IR group) groups were formed. Intraperitoneal CeO2 was administered at a dose of 0.5 mg/kg 30 min before left thoracotomy and left main coronary (LAD) ligation, and myocardial muscle ischemia was induced for 30 min. After LAD ligation was removed, reperfusion was performed for 120 min. All rats were euthanized using ketamine, and blood was collected. Liver and kidney tissue samples were evaluated histopathologically. Serum AST (aspartate aminotransferase), ALT (alanine aminotransaminase), GGT (gamma-glutamyl transferase), glucose, TOS (Total Oxidant Status), and TAS (Total Antioxidant Status) levels were also measured. Results: Necrotic cell and mononuclear cell infiltration in the liver parenchyma of rats in the IR group was observed to be significantly increased compared to the other groups. Hepatocyte degeneration was greater in the IR group compared to groups C and CO. Vascular vacuolization and hypertrophy, tubular degeneration, and necrosis were increased in the kidney tissue of the IR group compared to the other groups. Tubular dilatation was significantly higher in the IR group than in the C and CO groups. TOS was significantly higher in all groups than in the IR group (p < 0.0001, p < 0.0001, and p = 0.006, respectively). However, TAS level was lower in the IR group than in the other groups (p = 0.002, p = 0.020, and p = 0.031, respectively). Renal and liver histopathological findings decreased significantly in the CO-IR group compared to the IR group. A decrease in the TOS level and an increase in the TAS level were found compared to the IR group. The AST, ALT, GGT, and Glucose levels are shown. Conclusions: CeO2 administered before ischemia-reperfusion reduced oxidative stress and ameliorated IR-induced damage in distant organs. We suggest that CeO2 exerts protective effects in the myocardial IR model.

Postpartum Renal Cortical Necrosis: A Case Series

Rationale & Objective

Postpartum renal cortical necrosis (postpartum RCN) is a severe form of obstetric acute kidney injury. This study aimed to identify clinicopathologic features in Chinese postpartum RCN cases to determine how pathologic findings may contribute to the treatment and prognosis.

Study Design

Single-center, case series.

Setting & Participants

Twelve patients with postpartum RCN had kidney biopsies at Peking University First Hospital between 2014 and 2021. The diagnosis of postpartum RCN was made according to typical magnetic resonance imaging or pathologic features. Clinical, laboratory, and pathologic data were compared between patients with estimated glomerular filtration rate <30 (poor outcome) and ≥30 mL/min/1.73 m2 after 6 months.

Observations

All patients with postpartum RCN presented with stage 3 acute kidney injury attributed to a probable atypical hemolytic uremic syndrome. Pregnancy terminations occurred at a median gestational age of 35.5 weeks. Kidney biopsy was performed from 18 days to 4 months from delivery. On biopsy, hemoglobin, platelet count, and lactate dehydrogenase levels had been restored to 137 g/L, 214 × 109/L, and 231.50 ± 65.01 U/L, respectively. Four patients exhibited poor outcome, demonstrating higher schistocyte count, serum creatinine, and mean arterial pressure at onset. Pathologically, glomerular segmental sclerosis was prevalent. The "not otherwise specified" variant was the most common type, followed by collapsing variant, cellular variant, and tip variant. Patients with poor kidney outcome had more glomerular coagulative necrosis, capillary thrombosis, extensive cortical coagulative necrosis, and pronounced arteriole/artery lesions including increased interlobular arteriole intimal edema and fibrin thrombosis, but a lower occurrence of segmental sclerosis.

Limitations

Limited sample size and retrospective design.

Conclusions

We identified key pathologic features in patients with postpartum RCN and atypical hemolytic uremic syndrome, highlighting the necessity for more effective therapeutic options. There is a clear demand for noninvasive biomarkers that can accurately track disease progression and inform treatment duration for long-term outcomes improvement.

Protective effects of lupeol in rats with renal ischemia‑reperfusion injury

Acute kidney injury (AKI) caused by ischemia and, exogenous or endogenous nephrotoxic agents poses a serious health issue. AKI is seen in 1% of all hospital admissions, 2-5% of hospitalizations and 67% of intensive care unit (ICU) patients. The in-hospital mortality rates for AKI is 40-50, and >50% for ICU patients. Ischemia-reperfusion (I/R) injury in the kidney can activate inflammatory responses and oxidative stress, resulting in AKI. The common endpoint in acute tubular necrosis is a cellular insult secondary to ischemia or direct toxins, which results in effacement of brush border, cell death and decreased function of tubular cells. The aim of the present study was to assess if the reported antioxidant and anti-inflammatory agent lupeol can exert any effects against renal I/R damage. In total, 24 Wistar Albino rats were randomly assigned into four groups of 6, namely Sham, lupeol, ischemia and therapy groups. In the lupeol group, intraperitoneal administration of 100 mg/kg lupeol was given 1 h before laparotomy, whilst only laparotomy was conducted in the sham group. The renal arteries of both kidneys were clamped for 45 min, 1 h after either intraperitoneal saline injection (in the ischemia group) or 100 mg/kg lupeol application (in the therapy group). The blood samples and renal tissues of all rats were collected after 24 h. In blood samples, blood urea nitrogen (BUN) was measured by the urease enzymatic method, and creatinine was measured by the kinetic Jaffe method. Using ELISA method, TNF-α and IL-6 levels were measured in the blood samples, whereas malondialdehyde (MDA), glutathione (GSH), caspase-3 levels were measured in kidney tissues. In addition, kidney histopathological analysis was performed by evaluating the degree of degeneration, tubular dilatation, interstitial lymphocyte infiltration, protein cylinders, necrosis and loss of brush borders. It was determined that renal damage occurred due to higher BUN, creatinine, MDA, TNF-α and caspase-3 values observed in the kidney tissues and blood samples of rats in ischemia group compared with the Sham group. Compared with those in the ischemia group, rats in the therapy group exhibited increased levels of GSH and reduced levels of BUN, TNF-α, MDA. Furthermore, the ischemia group also had reduced histopathological damage scores. Although differences in creatinine, IL-6 and caspase-3 levels were not statistically significant, they were markedly reduced in the treatment group. Taken together, these findings suggest that lupeol can prevent kidney damage as mainly evidenced by the reduced histopathological damage scores, decreased levels of oxidative stress and reduced levels of inflammatory markers. These properties may allow lupeol to be used in the treatment of AKI.

PET image-guided kidney injury theranostics enabled by a bipyramidal DNA framework

Understanding the pharmacokinetic profiles of nanomaterials in living organisms is essential for their application in disease treatment. Bipyramidal DNA frameworks (BDFs) are a type of DNA nanomaterial that have shown prospects in the fields of molecular imaging and therapy. To serve as a reference for disease-related studies involving the BDF, we constructed a 68Ga-BDF and employed positron emission tomography (PET) imaging to establish its pharmacokinetic model in healthy mice. Our investigation revealed that the BDF was primarily eliminated from the body via the urinary system. Ureteral obstruction could significantly alter the metabolism of the urinary system. By utilizing the established pharmacokinetic model, we sensitively observed distinct imaging indicators in unilateral ureteral obstruction and acute kidney injury (a complication of ureteral obstruction) mouse models. Furthermore, we observed that the BDF showed therapeutic effects in an AKI model. We believe that the established pharmacokinetic model and unique renal excretion characteristics of the BDF will provide researchers with more information for studying kidney diseases.

Mesoscale size-promoted targeted therapy for acute kidney injury through combined RONS scavenging and inflammation alleviation strategy

Acute kidney injury (AKI) is a heterogeneous, high-mortality clinical syndrome with diverse pathogenesis and prognosis, but it lacks the effective therapy clinically. Its pathogenesis is associated with production of reactive oxygen/nitrogen species and infiltration of inflammatory cells. To overcome these pathogenic factors and improve the therapeutic efficiency, we synthesized triptolide-loaded mesoscale polydopamine melanin-mimetic nanoparticles (MeNP4TP) as the antioxidant plus anti-inflammatory therapeutic platform to synergistically scavenge reactive oxygen/nitrogen species (RONS), inhibit the activity of macrophages and dendritic cells, and generate Treg cells for AKI therapy. It was demonstrated that mesoscale size was beneficial for MeNP4TP to specifically accumulate at renal tubule cells, and MeNP4TP could significantly attenuate oxidative stress, reduce proinflammatory immune cells in renal, and repair renal function in cisplatin-induced AKI mouse model. MeNP4TP might be a potential candidate to inhibit oxidative damages and inflammatory events in AKI.

Molecular Mechanisms of Oxidative Stress in Acute Kidney Injury: Targeting the Loci by Resveratrol

Reactive oxygen species are a group of cellular molecules that stand as double-edged swords, their good and bad being discriminated by a precise balance. Several metabolic reactions in the biological system generate these molecules that interact with cellular atoms to regulate functions ranging from cell homeostasis to cell death. A prooxidative state of the cell concomitant with decreased clearance of such molecules leads to oxidative stress, which contributes as a prime pathophysiological mechanism in various diseases including renal disorders, such as acute kidney injury. However, targeting the generation of oxidative stress in renal disorders by an antioxidant, resveratrol, is gaining considerable therapeutic importance and is known to improve the condition in preclinical studies. This review aims to discuss molecular mechanisms of oxidative stress in acute kidney injury and its amelioration by resveratrol. The major sources of data were PubMed and Google Scholar, with studies from the last five years primarily included, with significant earlier data also considered. Mitochondrial dysfunction, various enzymatic reactions, and protein misfolding are the major sources of reactive oxygen species in acute kidney injury, and interrupting these loci of generation or intersection with other cellular components by resveratrol can mitigate the severity of the condition.

Single cell and spatial transcriptomics analysis of kidney double negative T lymphocytes in normal and ischemic mouse kidneys

T cells are important in the pathogenesis of acute kidney injury (AKI), and TCR+CD4-CD8- (double negative-DN) are T cells that have regulatory properties. However, there is limited information on DN T cells compared to traditional CD4+ and CD8+ cells. To elucidate the molecular signature and spatial dynamics of DN T cells during AKI, we performed single-cell RNA sequencing (scRNA-seq) on sorted murine DN, CD4+, and CD8+ cells combined with spatial transcriptomic profiling of normal and post AKI mouse kidneys. scRNA-seq revealed distinct transcriptional profiles for DN, CD4+, and CD8+ T cells of mouse kidneys with enrichment of Kcnq5, Klrb1c, Fcer1g, and Klre1 expression in DN T cells compared to CD4+ and CD8+ T cells in normal kidney tissue. We validated the expression of these four genes in mouse kidney DN, CD4+ and CD8+ T cells using RT-PCR and Kcnq5, Klrb1, and Fcer1g genes with the NIH human kidney precision medicine project (KPMP). Spatial transcriptomics in normal and ischemic mouse kidney tissue showed a localized cluster of T cells in the outer medulla expressing DN T cell genes including Fcer1g. These results provide a template for future studies in DN T as well as CD4+ and CD8+ cells in normal and diseased kidneys.

Protective effects of limb remote ischemic per-conditioning on the heart injury induced by renal ischemic-reperfusion through the interaction of the apelin with the RAS/iNOS pathway

Introduction

Remote ischemic conditioning upregulates endogenous protective pathways in response to ischemia-reperfusion injury. This study tested the hypothesis that limb remote ischemic per- conditioning (RIPerC) exerts cardioprotective effects via the renin-angiotensin system (RAS)/inducible nitric oxide synthase (iNOS)/apelin pathway.

Methods

Renal ischemia-reperfusion injury (I/R) was induced by bilateral occlusion of the renal pedicles for 60 minutes, followed by 24 hours of reperfusion; sham-operated rats served as controls. RIPerC was induced by four cycles (5 minutes) of limb ischemia-reperfusion along with bilateral renal ischemia. The functional disturbance was evaluated by renal (BUN and creatinine) and cardiac (troponin I and lactate dehydrogenase) injury biomarkers.

Results

Renal I/R injury increased renal and cardiac injury biomarkers that were reduced in the RIPerC group. Histopathological findings of the kidney and heart were also suggestive of amelioration injury-induced changes in the RIPerC group. Assessment of cardiac electrophysiology revealed that RIPerC ameliorated the decline in P wave duration without significantly affecting other cardiac electrophysiological changes. Further, renal I/R injury increased the plasma (322.40±34.01 IU/L), renal (8.27±1.10 mIU/mg of Protein), and cardiac (68.28±10.28 mIU/mg of protein) angiotensin-converting enzyme (ACE) activities in association with elevations in the plasma and urine nitrite (25.47±2.01 & 16.62±3.05 μmol/L) and nitrate (15.47±1.33 & 5.01±0.96 μmol/L) levels; these changes were reversed by RIPerC. Further, renal ischemia-reperfusion injury significantly (P=0.047) decreased the renal (but not cardiac) apelin mRNA expression, while renal and cardiac ACE2 (P<0.05) and iNOS (P=0.043) mRNA expressions were significantly increased compared to the sham group; these effects were largely reversed by RIPerC.

Conclusion

Our results indicated that RIPerC protects the heart against renal ischemia- reperfusion injury, likely via interaction of the apelin with the RAS/iNOS pathway.

Systemic Mutation of Ncf1 Ameliorates Obstruction-Induced Renal Fibrosis While Macrophage-Rescued NCF1 Further Alleviates Renal Fibrosis

Aims: NCF1, a subunit of the NADPH oxidase 2 (NOX2), first described the expression in neutrophils and macrophages and participated in the pathogenesis from various systems. However, there are controversial findings on the role of NCF1 in different kinds of kidney diseases. In this study, we aim to pinpoint the specific role of NCF1 in the progression of renal fibrosis induced by obstruction. Results: In this study, NCF1 expression was upregulated in kidney biopsies of chronic kidney disease patients. The expression level of all subunits of the NOX2 complex was also significantly increased in the unilateral ureteral obstruction (UUO) kidney. Then, we used wild-type mice and Ncf1 mutant mice (Ncf1m1j mice) to perform UUO-induced renal fibrosis. Results demonstrated that Ncf1m1j mice exhibited mild renal fibrosis but increased macrophages count and CD11b+Ly6Chi macrophage proportion. Next, we compared the renal fibrosis degree between Ncf1m1j mice and Ncf1 macrophage-rescued mice (Ncf1m1j.Ncf1Tg-CD68 mice). We found that rescuing NCF1 expression in macrophages further alleviated renal fibrosis and decreased macrophage infiltration in the UUO kidney. In addition, flow cytometry data showed fewer CD11b+Ly6Chi macrophages in the kidney of the Ncf1m1j.Ncf1Tg-CD68 group than the Ncf1m1j group. Innovation: We first used the Ncf1m1j mice and Ncf1m1j.Ncf1Tg-CD68 mice to detect the role of NCF1 in the pathological process of renal fibrosis induced by obstruction. Also, we found that NCF1 expressed in different cell types exerts opposing effects on obstructive nephropathy. Conclusion: Taken together, our findings support that systemic mutation of Ncf1 ameliorates renal fibrosis induced by obstruction, and rescuing NCF1 in macrophages further alleviates renal fibrosis.

Natural Products in Renal-Associated Drug Discovery

The global increase in the incidence of kidney failure constitutes a major public health problem. Kidney disease is classified into acute and chronic: acute kidney injury (AKI) is associated with an abrupt decline in kidney function and chronic kidney disease (CKD) with chronic renal failure for more than three months. Although both kidney syndromes are multifactorial, inflammation and oxidative stress play major roles in the diversity of processes leading to these kidney malfunctions. Here, we reviewed various publications on medicinal plants with antioxidant and anti-inflammatory properties with the potential to treat and manage kidney-associated diseases in rodent models. Additionally, we conducted a meta-analysis to identify gene signatures and associated biological processes perturbed in human and mouse cells treated with antioxidants such as epigallocatechin gallate (EGCG), the active ingredient in green tea, and the mushroom Ganoderma lucidum (GL) and in kidney disease rodent models. We identified EGCG- and GL-regulated gene signatures linked to metabolism; inflammation (NRG1, E2F1, NFKB1 and JUN); ion signalling; transport; renal processes (SLC12A1 and LOX) and VEGF, ERBB and BDNF signalling. Medicinal plant extracts are proving to be effective for the prevention, management and treatment of kidney-associated diseases; however, more detailed characterisations of their targets are needed to enable more trust in their application in the management of kidney-associated diseases.

Vitamin A and retinoid signaling in the kidneys

Vitamin A (VA, retinol) and its metabolites (commonly called retinoids) are required for the proper development of the kidney during embryogenesis, but retinoids also play key roles in the function and repair of the kidney in adults. Kidneys filter 180-200 liters of blood per day and each kidney contains approximately 1 million nephrons, which are often referred to as the 'functional units' of the kidney. Each nephron consists of a glomerulus and a series of tubules (proximal tubule, loop of Henle, distal tubule, and collecting duct) surrounded by a network of capillaries. VA is stored in the liver and converted to active metabolites, most notably retinoic acid (RA), which acts as an agonist for the retinoic acid receptors ((RARs α, β, and γ) to regulate gene transcription. In this review we discuss some of the actions of retinoids in the kidney after injury. For example, in an ischemia-reperfusion model in mice, injury-associated loss of proximal tubule (PT) differentiation markers occurs, followed by re-expression of these differentiation markers during PT repair. Notably, healthy proximal tubules express ALDH1a2, the enzyme that metabolizes retinaldehyde to RA, but transiently lose ALDH1a2 expression after injury, while nearby myofibroblasts transiently acquire RA-producing capabilities after injury. These results indicate that RA is important for renal tubular injury repair and that compensatory mechanisms exist for the generation of endogenous RA by other cell types upon proximal tubule injury. ALDH1a2 levels also increase in podocytes, epithelial cells of the glomeruli, after injury, and RA promotes podocyte differentiation. We also review the ability of exogenous, pharmacological doses of RA and receptor selective retinoids to treat numerous kidney diseases, including kidney cancer and diabetic kidney disease, and the emerging genetic evidence for the importance of retinoids and their receptors in maintaining or restoring kidney function after injury. In general, RA has a protective effect on the kidney after various types of injuries (eg. ischemia, cytotoxic actions of chemicals, hyperglycemia related to diabetes). As more research into the actions of each of the three RARs in the kidney is carried out, a greater understanding of the actions of vitamin A is likely to lead to new insights into the pathology of kidney disorders and the development of new therapies for kidney diseases.

Renal, but not platelet or skin, extracellular vesicles decrease oxidative stress, enhance nascent peptide synthesis, and protect from ischemic renal injury

Acute kidney injury (AKI) is deadly and expensive, and specific, effective therapy remains a large unmet need. We have demonstrated the beneficial effects of transplanted adult tubular cells and extracellular vesicles (EVs; exosomes) derived from those renal cells on experimental ischemic AKI, even when administered after renal failure is established. To further examine the mechanisms of benefit with renal EVs, we tested the hypothesis that EVs from other epithelia or platelets (a rich source of EVs) might be protective, using a well-characterized ischemia-reperfusion model. When given after renal failure was present, renal EVs, but not those from skin or platelets, markedly improved renal function and histology. The differential effects allowed us to examine the mechanisms of benefit with renal EVs. We found significant decreases in oxidative stress postischemia in the renal EV-treated group with preservation of renal superoxide dismutase and catalase as well as increases in anti-inflammatory interleukin-10. In addition, we propose a novel mechanism of benefit: renal EVs enhanced nascent peptide synthesis following hypoxia in cells and in postischemic kidneys. Although EVs have been used therapeutically, these results serve as "proof of principle" to examine the mechanisms of injury and protection.NEW & NOTEWORTHY Acute kidney injury is common and deadly, yet the only approved treatment is dialysis. Thus, a better understanding of injury mechanisms and potential therapies is needed. We found that organ-specific, but not extrarenal, extracellular vesicles improved renal function and structure postischemia when given after renal failure occurred. Oxidative stress was decreased and anti-inflammatory interleukin-10 increased with renal, but not skin or platelet, exosomes. We also propose enhanced nascent peptide synthesis as a novel protective mechanism.

Molecular cloning, tissues distribution, and function analysis of thioredoxin-like protein-1 (TXNL1) in Chinese giant salamanders Andrias davidianus

Thioredoxin-like protein-1 (TXNL1) is the member of thioredoxin superfamily, a family of thiol oxidoreductases. TXNL1 plays an important role in scavenging ROS and the maintenance of cellular redox balance. However, its physiological functions in Andrias davidianus have not been well understood. In the present study, the full-length cDNA encoding thioredoxin-like protein-1 (AdTXNL1) of A. davidianus was cloned, the mRNA tissue distribution was analyzed, and the function was characterized. The Adtxnl1 cDNA contained an open reading frame (ORF) of 870 bp encoding a polypeptide of 289 amino acids with the N-terminal TRX domain, a Cys³⁴-Ala³⁵-Pro³⁶-Cys³⁷ (CAPC) motif, and the C-terminal proteasome-interacting thioredoxin domain (PITH). The mRNA of AdTXNL1 was expressed in a wide range of tissues, with the highest level in the liver. The transcript level of AdTXNL1 was significantly up-regulated post Aeromonas hydrophila challenge in liver tissue. Moreover, the recombinant AdTXNL1 protein was produced and purified, and used to investigate the antioxidant activity. In the insulin disulfide reduction assay, rAdTXNL1 exhibited strong antioxidant capability. Altogether, the thioredoxin-like protein-1 may be involved in reduction/oxidation (redox) balance and as an important immunological gene in A. davidianus.

Assessment of knowledge, attitude, and practices of acute kidney injury incidence with co-administration of piperacillin/tazobactam and vancomycin among healthcare workers: A cross-sectional study

Background

No studies have identified a link between acute kidney injury (AKI) incidence due to the co-administration of vancomycin and piperacillin/tazobactam (VPT) and healthcare providers' knowledge, attitudes, and practices. We aimed to (1) assess the knowledge, attitudes, and practices towards AKI due to VPT co-administration among healthcare providers in Saudi Arabia, and (2) examine the relationship between healthcare providers' knowledge and attitudes about AKI due to VPT co-administration and their practices.

Methods

This cross-sectional study was conducted between February 2022 and April 2022. Healthcare providers, including physicians, pharmacists, and nurses, were included in the study population. The correlation coefficient assessed the relationship between knowledge, attitude, and practice. Spearman's rho was used as a test statistic.

Results

Of the invited healthcare providers, 192 responded to the survey. A significant difference in knowledge was found among healthcare providers for two variables: the definition of AKI (p < 0.001) and appropriate management of AKI due to VPT (p = 0.002). Physicians were found to rely less on the most common causative organisms of infection to guide empirical antibiotic therapy (p < 0.001). In addition, physicians were less likely to switch piperacillin/tazobactam to cefepime or meropenem in combination with vancomycin with AKI incidence (p = 0.001). A positive attitude towards the perceived AKI risk with VPT was positively correlated with avoiding using VPT unless no alternatives were available (Rho = 0.336) and taking protective measures when using VPT (Rho = 0.461).

Conclusion

Deviation has been observed in the knowledge, attitudes, and practices of AKI incidence with the co-administration of piperacillin/tazobactam and vancomycin among healthcare workers. Interventions at the organizational level are recommended to guide best practices.

Single Atom-Engineered NIR-II Gold Clusters with Ultrahigh Brightness and Stability for Acute Kidney Injury

Near-infrared-II (NIR-II) imaging has shown great potential for monitoring the pathological progression and deep tissue imaging but is limited to present unmet NIR-II agent. Present fluorophores show a promising prospect for NIR-II imaging, but brightness and photostability are still highly challenging during real-time monitoring. In this work, atom-engineered NIR-II Au₂₄ Cd₁  clusters with ultrahigh brightness, stability, and photostability are developed via single atomic Cd doping. Single atom Cd substitutions contribute to Cd 4d state in HOMO and redistribution of energy level near the gap, exhibiting 56-fold fluorescence enhancement of Au₂₄ Cd₁  clusters. Meanwhile, single atomic Cd reinforces CdAu bond energy, formation energy, and stabilized cluster structure, leading to persistent stability for up to 1 month without decay, as well as excellent photostability of 1 h without photobleaching, much longer than clinically approved indocyanine green (<5 min). In vivo imaging shows gold clusters can monitor acute kidney injury (AKI) even after 72 h of injury, enabling evaluating progression at a very long window. Meanwhile, the bioactive gold clusters can alleviate AKI-induced oxidative stress damage and acute neuroinflammation. Single atom-engineered gold clusters exhibit molecular tracking and diagnostic prospect in kidney-related diseases.

Investigating the effect of dehydromiltirone on septic AKI using a network pharmacology method, molecular docking, and experimental validation

Acute kidney injury (AKI) is a severe and frequent complication of sepsis that occurs in intensive care units with inflammation and rapid decline in renal function as the main pathological features. Systemic inflammation, microvascular dysfunction, and tubule injury are the main causes of sepsis-induced AKI (SI-AKI). The high prevalence and death rate from SI-AKI is a great challenge for clinical treatment worldwide. However, in addition to hemodialysis, there is no effective drug to improve renal tissue damage and alleviate the decline in kidney function. We conducted a network pharmacological analysis of Salvia miltiorrhiza (SM), a traditional Chinese medicine, which is widely used for the treatment of kidney disease. Then, we combined molecular docking and a dynamics simulation to screen for the active monomer dehydromiltirone (DHT) that has therapeutic effects on SI-AKI and investigated its potential mechanism of action through experimental validation. The components and targets of SM were obtained by searching the database, and 32 overlapping genes were screened by intersection analysis with AKI targets. GO and KEGG data showed that the functions of a common gene were closely related to oxidative stress, mitochondrial function, and apoptosis. The molecular docking results combined with molecular dynamics simulations provide evidence for a binding model between DHT and cyclooxygenase-2 (COX2), both of which are mainly driven by van der Waals interactions and a hydrophobic effect. In vivo, we found that mice pretreated with an intraperitoneal injection of DHT (20 mg/kg/d) for 3 days ameliorated CLP surgery-induced renal function loss and renal tissue damage and inhibited inflammatory mediators IL-6, IL-1β, TNF-α, and MCP-1 production. In vitro, the DHT pretreatment decreased LPS-induced expression of COX2, inhibited cell death and oxidative stress, alleviated mitochondrial dysfunction, and restrained apoptosis in HK-2 cells. Our research indicates that the renal preventive effect of DHT is related to maintaining mitochondrial dynamic balance, restoring mitochondrial oxidative phosphorylation, and inhibiting cell apoptosis. The findings in this study provide a theoretical basis and a novel method for the clinical therapy of SI-AKI.

Therapeutic propensity of ginsenosides Rg1 and Rg3 in rhabdomyolysis-induced acute kidney injury and renohepatic crosstalk in rats

BACKGROUND

Ginseng is a traditional herbal medicine used for thousands of years in Southeast Asian countries because of its medicinal properties. Ginsenosides Rg1 and Rg3 have demonstrated therapeutic properties against a broad spectrum of diseases.

PURPOSE

Here in this study, we investigated the therapeutic efficacy of Rg1 and Rg3 in alleviating glycerol-induced acute kidney injury, also known as rhabdomyolysis-induced acute kidney injury (RAKI).

METHODS

AKI was induced in male Wistar rats through intramuscular injection of 10 mL/kg glycerol and simultaneous oral treatment of ginsenosides Rg1 and Rg3 for 3 days. We also evaluated the therapeutic potential of Rg1 and Rg3 on human embryonic kidney epithelial (HEK-293). Cell viability and LDH assay were performed on HEK-293 cells to evaluate the toxicity of Rg1 and Rg3. Evaluation of important kidney damage markers such as creatinine and blood urea nitrogen (BUN) was carried out at different time points from the rat serum. Histopathological analysis was performed on kidney tissues. We also performed experiments such as ELISA assay, immunohistochemistry, immunofluorescence staining, COMET assay, western blotting, TUNEL assay, and flow cytometry to obtain results.

RESULTS

Rg1 and Rg3 significantly downregulated the expression of kidney damage markers such as creatinine and BUN in a dose-dependent manner. Histopathological analysis revealed damage across the glomerulus, tubules, and collecting duct rendering the kidney dysfunctional in glycerol treatment groups. However, Rg1 and Rg3 treated groups showed a significant reduction in tubular necrosis at both 10 and 20 mg/kg. There was also a sharp downregulation of oxidative and ER stress markers. Additionally, we observed nuclear translocation of Nrf2 which were more prominent in kidney tissues. Rg1 and Rg3 were also able to mitigate apoptotic cell death in vitro and in vivo evaluated through immunofluorescence staining for p53, TUNEL assay, flow cytometry, and immunoblotting for intrinsic apoptosis markers.

CONCLUSION

In summary, we conclude that Rg1 and Rg3 exhibited natural therapeutic remedy against AKI.

Punica granatum L. Polyphenolic Extract as an Antioxidant to Prevent Kidney Injury in Metabolic Syndrome Rats

Introduction

Obesity and metabolic syndrome (MetS) constitute a rapidly increasing health problem and contribute to the development of multiple comorbidities like acute and chronic kidney disease. Insulin resistance, inappropriate lipolysis, and excess of free fatty acids (FFAs) are associated with glomerulus hyperfiltration and atherosclerosis. The important component of MetS, oxidative stress, is also involved in the destabilization of kidney function and the progression of kidney injury. Natural polyphenols have the ability to reduce the harmful effect of reactive oxygen and nitrogen species (ROS/RNS). Extract derived from Punica granatum L. is rich in punicalagin that demonstrates positive effects in MetS and its associated diseases. The aim of the study was to investigate the effect of bioactive substances of pomegranate peel to kidney damage associated with the MetS.

Methods

In this study, we compared biomarkers of oxidative stress in kidney tissue of adult male Zucker Diabetic Fatty (ZDF) rats with MetS and healthy controls that were treated with Punica granatum L. extract at a dose of 100 or 200 mg/kg. Additionally, we evaluated the effect of polyphenolic extract on kidney injury markers and remodeling. The concentration of ROS/RNS, oxLDL, glutathione (GSH), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), metalloproteinase 2 and 9 (MMP-2, MMP-9), and the activity of superoxide dismutase (SOD) and catalase (CAT) were measured.

Results

The data showed significant differences in oxidative stress markers between treated and untreated MetS rats. ROS/RNS levels, oxLDL concentration, and SOD activity were lower, whereas CAT activity was higher in rats with MetS receiving polyphenolic extract. After administration of the extract, markers for kidney injury (NGAL, KIM-1) decreased.

Conclusion

Our study confirmed the usefulness of pomegranate polyphenols in the treatment of MetS and the prevention of kidney damage. However, further, more detailed research is required to establish the mechanism of polyphenol protection.

Amelioration of 5-Fluorouracil Induced Nephrotoxicity by Acacia catechu through Overcoming Oxidative Damage and Inflammation in Wistar Rats

AIM

The research intended to explore the possible nephroprotective potential of the ethyl acetate fraction derived from Acacia catechu leaves against nephrotoxicity brought about by 5-fluorouracil (5-FU) in Wistar rats.

BACKGROUND

While possessing strong anticancer properties, 5-FU is hindered in its therapeutic application due to significant organ toxicity linked to elevated oxidative stress and inflammation.

OBJECTIVE

The study is undertaken to conduct an analysis of the ethyl acetate fraction of A. catechu leaves both in terms of quality and quantity, examining its impact on different biochemical and histopathological parameters within the context of 5-FU-induced renal damage in rats and elucidation of the mechanism behind the observed outcomes.

METHODOLOGY

Intraperitoneal injection of 5-FU at a dosage of 20 mg/kg/day over 5 days was given to induce nephrotoxicity in rats. The evaluation of nephrotoxicity involved quantifying serum creatinine, urea, uric acid, and electrolyte concentrations. Furthermore, superoxide dismutase, catalase antioxidant enzymes, and TNF-α concentration in serum were also measured.

RESULTS

5-FU injection led to the initiation of oxidative stress within the kidneys, leading to modifications in renal biomarkers (including serum creatinine, urea, uric acid, and Na+, K+ levels), and a reduction in antioxidant enzymes namely superoxide dismutase and catalase. Notably, the presence of the inflammatory cytokine TNF-α was significantly elevated due to 5-FU. Microscopic examination of renal tissue revealed tubular degeneration and congestion. However, treatment involving the ethyl acetate fraction derived from A. catechu leaves effectively and dose-dependently reversed the changes observed in renal biomarkers, renal antioxidant enzymes, inflammatory mediators, and histopathological features, bringing them closer to normal conditions. The observed recuperative impact was mainly attributed to the antioxidant and antiinflammatory properties of the fraction.

CONCLUSION

The ethyl acetate fraction of A. catechu leaves exhibited a mitigating influence on the renal impairment caused by 5-FU, showcasing its potential as a nephroprotective agent capable of preventing and ameliorating 5-FU-induced nephrotoxicity.

A Hydrodistillate of Gynostemma pentaphyllum and Damulin B Prevent Cisplatin-Induced Nephrotoxicity In Vitro and In Vivo via Regulation of AMPKα1 Transcription

The clinical application of cisplatin, one of the most effective chemotherapeutic agents used to treat various cancers, has been limited by the risk of adverse effects, notably nephrotoxicity. Despite intensive research for decades, there are no effective approaches for alleviating cisplatin nephrotoxicity. This study aimed to investigate the protective effects and potential mechanisms of a Gynostemma pentaphyllum leaves hydrodistillate (GPHD) and its major component, damulin B, against cisplatin-induced nephrotoxicity in vitro and in vivo. A hydro-distillation method can extract large amounts of components within a short period of time using non-toxic, environmentally friendly solvent. We found that the levels of AMP-activated protein kinase α1 (AMPKα1), reactive oxygen species (ROS), and apoptosis were tightly associated with each other in HEK293 cells treated with cisplatin. We demonstrated that AMPKα1 acted as an anti-oxidant factor and that ROS generated by cisplatin suppressed the expression of AMPKα1 at the transcriptional level, thereby resulting in induction of apoptosis. Treatment with GPHD or damulin B effectively prevented cisplatin-induced apoptosis of HEK293 cells and cisplatin-induced acute kidney injury in mice by suppressing oxidative stress and maintaining AMPKα1 levels. Therefore, our study suggests that GPHD and damulin B may serve as prospective adjuvant agents against cisplatin-induced nephrotoxicity.

Heme Proteins and Kidney Injury: Beyond Rhabdomyolysis

Heme proteins, the stuff of life, represent an ingenious biologic strategy that capitalizes on the biochemical versatility of heme, and yet is one that avoids the inherent risks to cellular vitality posed by unfettered and promiscuously reactive heme. Heme proteins, however, may be a double-edged sword because they can damage the kidney in certain settings. Although such injury is often viewed mainly within the context of rhabdomyolysis and the nephrotoxicity of myoglobin, an increasing literature now attests to the fact that involvement of heme proteins in renal injury ranges well beyond the confines of this single disease (and its analog, hemolysis); indeed, through the release of the defining heme motif, destabilization of intracellular heme proteins may be a common pathway for acute kidney injury, in general, and irrespective of the underlying insult. This brief review outlines current understanding regarding processes underlying such heme protein-induced acute kidney injury (AKI) and chronic kidney disease (CKD). Topics covered include, among others, the basis for renal injury after the exposure of the kidney to and its incorporation of myoglobin and hemoglobin; auto-oxidation of myoglobin and hemoglobin; destabilization of heme proteins and the release of heme; heme/iron/oxidant pathways of renal injury; generation of reactive oxygen species and reactive nitrogen species by NOX, iNOS, and myeloperoxidase; and the role of circulating cell-free hemoglobin in AKI and CKD. Also covered are the characteristics of the kidney that render this organ uniquely vulnerable to injury after myolysis and hemolysis, and pathobiologic effects emanating from free, labile heme. Mechanisms that defend against the toxicity of heme proteins are discussed, and the review concludes by outlining the therapeutic strategies that have arisen from current understanding of mechanisms of renal injury caused by heme proteins and how such mechanisms may be interrupted.

Hydrogenated Germanene Nanosheets as an Antioxidative Defense Agent for Acute Kidney Injury Treatment

Acute kidney injury (AKI) is a sudden kidney dysfunction caused by aberrant reactive oxygen species (ROS) metabolism that results in high clinical mortality. The rapid development of ROS scavengers provides new opportunities for AKI treatment. Herein, the use of hydrogen-terminated germanene (H-germanene) nanosheets is reported as an antioxidative defense nanoplatform against AKI in mice. The simulation results show that 2D H-germanene can effectively scavenge ROS through free radical adsorption and subsequent redox reactions. In particular, the H-germanene exhibits high accumulation in injured kidneys, thereby offering a favorable opportunity for treating renal diseases. In the glycerol-induced murine AKI model, H-germanene delivers robust antioxidative protection against ROS attack to maintain normal kidney function indicators without negative influence in vivo. This positive in vivo antioxidative defense in living animals demonstrates that the present H-germanene nanoplatform is a powerful antioxidant against AKI and various anti-inflammatory diseases.

Hydrogenated Germanene Nanosheets as an Antioxidative Defense Agent for Acute Kidney Injury Treatment

Acute kidney injury (AKI) is a sudden kidney dysfunction caused by aberrant reactive oxygen species (ROS) metabolism that results in high clinical mortality. The rapid development of ROS scavengers provides new opportunities for AKI treatment. Herein, the use of hydrogen‐terminated germanene (H‐germanene) nanosheets is reported as an antioxidative defense nanoplatform against AKI in mice. The simulation results show that 2D H‐germanene can effectively scavenge ROS through free radical adsorption and subsequent redox reactions. In particular, the H‐germanene exhibits high accumulation in injured kidneys, thereby offering a favorable opportunity for treating renal diseases. In the glycerol‐induced murine AKI model, H‐germanene delivers robust antioxidative protection against ROS attack to maintain normal kidney function indicators without negative influence in vivo. This positive in vivo antioxidative defense in living animals demonstrates that the present H‐germanene nanoplatform is a powerful antioxidant against AKI and various anti‐inflammatory diseases.

Prominent Mitochondrial Injury as an Early Event in Heme Protein-Induced Acute Kidney Injury

Background

Mitochondrial injury occurs in and underlies acute kidney injury (AKI) caused by ischemia-reperfusion and other forms of renal injury. However, to date, a comprehensive analysis of this issue has not been undertaken in heme protein-induced AKI (HP-AKI). We examined key aspects of mitochondrial function, expression of proteins relevant to mitochondrial quality control, and mitochondrial ultrastructure in HP-AKI, along with responses to heme in renal proximal tubule epithelial cells.

Methods

The long-established murine glycerol model of HP-AKI was examined at 8 and 24 hours after HP-AKI. Indices of mitochondrial function (ATP and NAD+), expression of proteins relevant to mitochondrial dynamics, mitochondrial ultrastructure, and relevant gene/protein expression in heme-exposed renal proximal tubule epithelial cells in vitro were examined.

Results

ATP and NAD+ content and the NAD+/NADH ratio were all reduced in HP-AKI. Expression of relevant proteins indicate that mitochondrial biogenesis (PGC-1α, NRF1, and TFAM) and fusion (MFN2) were impaired, as was expression of key proteins involved in the integrity of outer and inner mitochondrial membranes (VDAC, Tom20, and Tim23). Conversely, marked upregulation of proteins involved in mitochondrial fission (DRP1) occurred. Ultrastructural studies, including novel 3D imaging, indicate profound changes in mitochondrial structure, including mitochondrial fragmentation, mitochondrial swelling, and misshapen mitochondrial cristae; mitophagy was also observed. Exposure of renal proximal tubule epithelial cells to heme in vitro recapitulated suppression of PGC-1α (mitochondrial biogenesis) and upregulation of p-DRP1 (mitochondrial fission).

Conclusions

Modern concepts pertaining to AKI apply to HP-AKI. This study validates the investigation of novel, clinically relevant therapies such as NAD+-boosting agents and mitoprotective agents in HP-AKI.

In Vitro Study of the Phytochemical Composition and Antioxidant, Immunostimulant, and Hemolytic Activities of Nigella sativa (Ranunculaceae) and Lepidium sativum Seeds

The Moroccan flora abounds and is an important reserve of medicinal plants. Nigella sativa and Lepidium sativum are plants that are widely used in traditional medicine for their multiple therapeutic properties. The current study aims to highlight the biological activities that can justify and valorize the use of these plants. Flavonoids, total phenols, condensed tannins, and sugars were determined. The biological activities tested were antioxidant by determining the IC50 (defined as the concentration of an antioxidant required to decrease the initial concentration by 50%; inversely related to the antioxidant capacity), hemagglutination, and hemolytic activities. Phytochemical quantification of the seed extracts indicated that the total phenol content was largely similar for both plants and in the order of 10 mg GAE (Gallic acid equivalent)/g. On the other hand, L. sativum seeds registered a higher content of flavonoids (3.09 ± 0.04 mg QE (quercetin equivalent)/g) as compared to Nigella saliva (0.258 ± 0.058). Concerning condensed tannins, N. saliva seeds present a higher amount with a value of 7.2 ± 0.025 mg/g as compared to L. sativum (1.4 ± 0.22 mg/g). Concerning the total sugar content, L. sativum shows a higher content (67.86 ± 0.87 mg/g) as compared to N. sativa (58.17 ± 0.42 mg/g); it is also richer in mucilage with a content of 240 mg as compared to 8.2 mg for N. saliva. Examination of the antioxidant activity using a DPPH (2.2-diphenyl 1-pycrilhydrazyl) test revealed that the EButOH (n-butanol extract) and EAE (ethyl acetate extract) extracts were the most active, with IC50 values of 48.7 and 50.65 μg/mL for the N. sativa extracts and 15.7 and 52.64 μg/mL for the L. sativum extracts, respectively. The results of the hemagglutination activity of the different extracts of the two plants prepared in the PBS (phosphate-buffered saline) medium showed significant agglutination for the L. sativum extract (1/50) compared to the N. sativa extract (1/20). An evaluation of the hemolytic effect of the crude extract of the studied seeds on erythrocytes isolated from rat blood incubated in PBS buffer compared to the total hemolysis induced by distilled water showed a hemolysis rate of 54% for Nigella sativa and 34% for L. sativum. In conclusion, the two plants studied in the current work exhibited high antioxidant potential, which could explain their beneficial properties.

The Effect of Polyphenols on Kidney Disease: Targeting Mitochondria

Mitochondrial function, including oxidative phosphorylation (OXPHOS), mitochondrial biogenesis, and mitochondria dynamics, are essential for the maintenance of renal health. Through modulation of mitochondrial function, the kidneys are able to sustain or recover acute kidney injury (AKI), chronic kidney disease (CKD), nephrotoxicity, nephropathy, and ischemia perfusion. Therapeutic improvement in mitochondrial function in the kidneys is related to the regulation of adenosine triphosphate (ATP) production, free radicals scavenging, decline in apoptosis, and inflammation. Dietary antioxidants, notably polyphenols present in fruits, vegetables, and plants, have attracted attention as effective dietary and pharmacological interventions. Considerable evidence shows that polyphenols protect against mitochondrial damage in different experimental models of kidney disease. Mechanistically, polyphenols regulate the mitochondrial redox status, apoptosis, and multiple intercellular signaling pathways. Therefore, this review attempts to focus on the role of polyphenols in the prevention or treatment of kidney disease and explore the molecular mechanisms associated with their pharmacological activity.

Salvianolate ameliorates renal tubular injury through the Keap1/Nrf2/ARE pathway in mouse kidney ischemia-reperfusion injury

ETHNOPHARMACOLOGICAL RELEVANCE

Acute kidney injury (AKI) is a common clinical disease characterized by rapid loss of renal function. Salvianolate is a prescribed Chinese medicine derived from traditional Chinese medicine Salvia miltiorrhiza bunge that possesses many pharmacological effects, the active components extracted from Salvia miltiorrhiza bunge have been proved to protect ischemia-reperfusion (I/R)-AKI.

AIM OF THE STUDY

This study aims to validate the therapeutic effect of SAL on I/R-AKI, and explore its potential pharmacological mechanism.

MATERIALS AND METHODS

Mice were pretreated with/without salvianolate (10, 30, and 90 mg/kg) before renal ischemia-reperfusion operation. Serum creatinine, BUN, and H&E staining were performed to evaluate renal function. Immunofluorescence analysis was conducted to measure renal tubular injury including inflammatory factors and peroxide level. Apoptosis of the kidney tissues was determined by TUNEL assay. Keap1-Nrf2-ARE and apoptosis signaling pathways were measured by Western blot, RT-PCR, and YO-PRO-1 staining in kidneys or NRK52E cells.

RESULTS

Pretreatment with SAL effectively alleviated renal function and ameliorated epithelial tubular injury, oxidative stress, and inflammatory response. Furthermore, the mechanistic study demonstrated that the SAL exerts anti-apoptotic effects through activation of the Keap1-Nrf2-ARE signaling pathway in renal tubular cells.

CONCLUSION

These findings indicate the therapeutic benefit of salvianolate in the protection of renal injury from ischemia-reperfusion, and strengthen the evidence for the AKI treatment strategy by the anti-oxidative stress response, suggesting that SAL may be a potential agent for the treatment of AKI.

Thymoquinone ameliorates amikacin induced oxidative damage in rat brain tissue

We investigated the potential neuroprotective effects of thymoquinone (TQ) on amikacin (AK) induced oxidative damage in rat brain. We used 21 male rats divided randomly into three equal groups. The control group was injected intraperitoneally (i.p.) with 0.5 ml 0.9% aqueous NaCl and given 1 ml 0.9% aqueous NaCl orally. The AK group was administered 1.2 g/kg aqueous AK i.p. as a single dose on the day 3 of the study. The AK + TQ group was given a single 1.2 g/kg dose of AK i.p. on the day 3 of the study plus 40 mg/kg/day TQ by oral gavage daily. Treatment with TQ increased serum ferritin and decreased serum calcium levels significantly. TQ also decreased NADPH oxidase-2, NADPH oxidase-4, and caspase-3 levels. Decreased malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) and catalase (CAT) activities were detected in the AK + TQ group compared to the AK group. TQ administration inhibited lipid peroxide formation and blocked oxidative reactions, which reduced the MDA level and increased SOD and CAT activities induced by AK. Oxidative damage caused by AK was ameliorated by TQ treatment owing to its antioxidative and anti-apoptotic effects. TQ may be a potential therapeutic agent for reducing the severity of AK induced oxidative damage to the brain.

Analysis of mRNA and protein kidney injury Molecule-1 (KIM-1) expression in a kidney model during the initiation phase of ischemia reperfusion injury

BACKGROUND

Kidney injury molecule-1 (KIM-1) is a transmembrane glycoprotein expressed predominantly on the proximal tubular epithelium.

OBJECTIVE

We wanted to see if there was a critical time for increased tubular damage and its related biomarker, KIM-1 mRNA, and protein expressions during the first 24 h of ischemia-reperfusion injury.

METHOD

An Experimental research used five male Rattus Norvegicus rats in each group. Bulldog clamp was used to clamp renal arteries and veins to create renal ischemia. Immunohistochemistry was used for the analysis of KIM-1 protein expression. While Tubular Injury Score was examined by Histopathology. RT-PCR was used for KIM-1 mRNA expression.

RESULTS

Tubular Injury Score (TIS) was significantly higher in ischemia than control. TIS remained similar after IR 30 min, peaked at IR 2 h, and decreased to the level of IR 30 min at IR 24 h.The KIM-1 mRNA expression was also higher in ischemia than in control. Similarly, KIM-1 mRNA expression increased more after IR 30 min, IR 2 h, and IR 24 h.The KIM-1 protein expression was higher in ischemia than in control. KIM-1 protein increased more after IR 30 min, IR for 2 h, and remained similar at IR for 24 h.KIM-1 mRNA and protein expressions at IR 2 h were significantly different compared to ischemia but not significantly different compared to that in IR 24 h.

CONCLUSIONS

KIM-1 mRNA and protein expressions increased within 24 h IR with the critical time was in the 2 h IR.

Olanzapine-Induced Therapeutic Hypothermia Attenuates Renal Injury in Rats after Asphyxial Cardiac Arrest and Resuscitation

Return of spontaneous circulation (ROSC) through cardiopulmonary resuscitation (CPR) after cardiac arrest (CA) causes post-cardiac arrest syndrome (PCAS) due to dysfunction in various organs, which provokes acute kidney injury because of renal ischemia-reperfusion injury. Therapeutic hypothermia (TH) can reduce PCAS after CA and ROSC. However, it needs to be more sophisticated and effective. Hence, we aimed to elucidate the protective effects of olanzapine-induced TH against renal injury in asphyxial CA-induced rats. Every rat’s body temperature was maintained at 33 °C for 6 h after administering olanzapine post-CA and ROSC. Olanzapine-induced TH dramatically increased the survival rate of the rats and ameliorated renal tissue damage. Moreover, it suppressed oxidative stress responses through preservation of mitochondrial function and endoplasmic reticulum stress as the main contributor of oxidative stress. Notably, these actions of olanzapine-induced TH were mediated through the Sirt3-related signaling pathway, including the maintenance of Sirt3 and FOXO3a protein expression and the activation of AMPKα and superoxide dismutase 1 (SOD2, a mitochondrial antioxidant). This study is the first to disclose the protective effects of olanzapine-induced TH against renal injury after CA and ROSC, suggesting that olanzapine-induced TH could be utilized for treating CA followed by ROSC.

Intravenous Administration of Cisplatin with Magnesium Sulfate Supplement May Prevent Kidney Toxicity in Rats: The Role of Gender and Magnesium Sulfate Dose

Background. Cisplatin (CP) is widely used to treat various kinds of malignancies, but to avoid its side effects of nephrotoxicity and hypomagnesemia, magnesium supplementation is a subject of debate. The current study was designed to determine the protective role of intravenous magnesium sulfate (MgSO4) against intravenous administration of CP in male and female rats. Method. In this case-control experimental study, 80 Wistar male and female rats in 12 groups of experiments were subjected to receive intravenous administration of CP accompanied with intravenous infusion of different doses (1, 3, and 10 mg/ml solution) of MgSO4 and were compared with the control groups. Results. CP administration increased blood urea nitrogen (BUN), creatinine (Cr), kidney tissue damage score (KTDS), and kidney weight (KW), and they were attenuated by the mid-dose of MgSO4 supplementation in female rats. However, in male rats, the increase of Cr, BUN, KTDS, and KW induced by CP was ameliorated by low, mid-, and high doses of MgSO4 supplements. The levels of these markers were significantly different between male and female rats in the mid-dose of MgSO4-treated group (BUN: $P=0.002$ , Cr: $P=0.005$ , KTDS: $P=0.002$ , and KW: $P=0.031$ ). CP reduced clearance of Cr (ClCr) in both male and female rats significantly compared to the control group of saline alone (Pmale = 0.002 and Pfemale = 0.001), and the mid- and high doses of MgSO4 supplements improved ClCr in female rats. There were also sex differences in ClCr in mid- ( $P=0.05$ ) and high ( $P=0.032$ ) doses of MgSO4-treated groups. CP accompanied with the mid-dose of MgSO4 supplement reduced the KTDS (Pmale = 0.04 and Pfemale = 0.004) and KW (Pmale = 0.002 and Pfemale = 0.042) in both male and female rats significantly when compared with the CP-alone-treated group, while there were also significant differences between the sexes (KTDS: $P=0.002$ and KW: $P=0.031$ ). CP accompanied with three different doses of MgSO4 supplements did not improve the serum levels of lactate dehydrogenase, urine level of sodium, malondialdehyde, urine flow, and nitrite statistically when compared with the CP-alone-treated group. Conclusion. The renal protective effect of MgSO4 could be dose and gender related.

Treatment of Acute Kidney Injury Using a Dual Enzyme Embedded Zeolitic Imidazolate Frameworks Cascade That Catalyzes In Vivo Reactive Oxygen Species Scavenging

Significant advances have been made in recent years for the utilization of natural enzymes with antioxidant properties to treat acute kidney injury (AKI). However, these enzymes have been of limited clinical utility because of their limited cellular uptake, poor pharmacokinetic properties, and suboptimal stability. We employed a novel biomimetic mineralization approach to encapsulate catalase (CAT) and superoxide dismutase (SOD) in a zeolitic imidazolate framework-8 (ZIF-8). Next, this SOD@CAT@ZIF-8 complex was anchored with MPEG₂₀₀₀-COOH to yield an MPEG₂₀₀₀-SOD@CAT@ZIF-8 (PSCZ) composite. The composite was then used as a stable tool with antioxidant properties for the integrated cascade-based treatment of AKI, remarkably improved intracellular enzyme delivery. This dual-enzyme-embedded metal-organic framework could effectively scavenge reactive oxygen species. In conclusion, the ZIF-8-based "armor plating" represents an effective means of shielding enzymes with improved therapeutic utility to guide the precision medicine-based treatment of AKI.

Senkyunolide I alleviates renal Ischemia-Reperfusion injury by inhibiting oxidative stress, endoplasmic reticulum stress and apoptosis

BACKGROUND

Ligusticum striatum DC. is traditionally used to treat ischemic diseases because of its potent effect against blood stasis and thrombosis, including various cardiovascular, cerebral and renal diseases. Senkyunolide I (SEI), which is the major active phthalide ingredient of Ligusticum striatum DC., is mainly distributed in kidney and has been shown to attenuate ischemia reperfusion injury in liver. However, the underlying effect of SEI against renal ischemia-reperfusion injury (IRI) remain unclear.

METHODS

Renal ischemia reperfusion mice model was established by clamping bilateral renal pedicles. In vitro oxidative stress model was induced by H₂O₂. Level of blood urea nitrogen (BUN) and serum creatinine (SCr) was tested for in vivo model evaluation, while cell viability was tested using CCK8 to evaluate in vitro model. SEI solution containing 1% DMSO was injected intraperitoneally in the I/R group, while normal saline containing 1% DMSO injected in the Sham group. Reduced glutathione (GSH) solution containing 1% DMSO was used as a positive control.

RESULTS

SEI protected renal function and structural integrity. It reversed the I/R-induced elevation of BUN, SCr levels and renal pathological injury. The secretion of proinflammatory cytokines including TNF-α and IL-6 was inhibited, and the renal apoptosis was attenuated by SEI. In addition, SEI played a protective role by reducing the production of reactive oxidative species (ROS), as shown by the elevated expression of antioxidant proteins including Nrf2, HO-1, NQO1, and reduced expression of endoplasmic reticulum stress (ERS) related proteins including GRP78 and CHOP. It also attenuated HK2 cell injury in an in vitro model induced by H₂O₂.

CONCLUSIONS

SEI alleviates renal injury induced by ischemia reperfusion with anti-inflammatory, anti-endoplasmic reticulum stress, anti-oxidative and anti-apoptotic effect.

The impact of Technetium-99m dimercapto-succinic acid scintigraphy on DNA damage and oxidative stress in children

BACKGROUND

Technetium-99m-dimercapto succinic acid (Tc-99m DMSA) scintigraphy is a commonly used imaging modality in children with urological abnormalities. The radiopharmaceuticals, which have the effects of ionising radiation, are used in this method. This study aimed to investigate the impact of the Tc-99m DMSA scan on renal oxidative stress and mononuclear leukocyte (MNL) DNA damage.

METHODS

Children, who were followed up by paediatric nephrology at Bezmialem Vakif University and underwent Tc-99m DMSA scintigraphy between April 2015 and January 2016 with the indication of detection of renal scars, were included in this study. The exclusion criteria were nephrolithiasis, history of premature birth and recent urinary tract infection 3 months prior to scintigraphy or antibiotic use in the last 1 month. 3 mL heparinised blood samples were obtained just before, immediately after and 1 week after the scintigraphy. MNL DNA damage, total antioxidant status (TAS) and total oxidant status (TOS) were measured in the blood samples. The oxidative stress index (OSI) was calculated. Spot urine samples were obtained from each patient before and within 3 days after performing the scintigraphy. TAS/Creatinine (TAS/Cr), TOS/Creatinine (TOS/Cr) and N-acetyl-glucosaminidase/creatinine (NAG/Cr) levels were measured in the urine samples.

RESULTS

Twenty-seven children were evaluated. The values between TAS, TOS and OSI levels in serum samples at baseline, immediately after and 1 week after the scintigraphy (P = .105, P = .913, and P = .721, respectively) showed no statistically significant difference. The levels of TAS/Cr, TOS/Cr, NAG/Cr ratios and OSI, which were evaluated from urine samples before and within 3 days after the scintigraphy scan were also similar (P = .391, P = .543, P = .819 and P = .179, respectively). The levels of DNA damage only increased following scintigraphy scan and decreased a week later (P < .05).

CONCLUSIONS

The effect of Tc-99m DMSA scintigraphy is insufficient to create oxidative damage, but it can cause DNA damage via the direct impact of ionising radiation which can be repaired again in a short time.

Quantitative Evaluation of Renal Cortex Perfusion Using Contrast-Enhanced Ultrasound Imaging Parameters in Ischemia-Reperfusion Injury in Rabbits

The aim of this study was to evaluate blood perfusion of the renal cortex during ischemia-reperfusion (I/R) injury using quantitative contrast-enhanced ultrasound (CEUS) parameters. In this experiment, 24 rabbits were randomly divided into four groups (N = 6): sham-operated group, 24-h post-operation for I/R injury group (24-h I/R), 3-d post-operation for I/R injury group (3-d I/R) and 5 d post-operation for I/R injury group (5 d I/R). All quantitative CEUS parameters were monitored and included the gradient from the start frame to the peak frame (Grad), area under the curve (Area), time-to-peak (TTP), difference between B(intercept intensity at t=0) and A(the intensity attenuation t= 0) and arrival time (AT). Subsequently, we analyzed the changes in these parameters, as well as the correlation between changes in CEUS parameters and pathological parameters. AT and TTP values peaked 3 d after I/R surgery, which correlated with the most significant pathological changes at the same time point. These parameters (such as AT, TTP and Grad) may be useful in dynamically monitoring the severity of tissue damage at the early stage of I/R injury.

Inflammation: improving understanding to prevent or ameliorate kidney diseases

Inflammatory processes are believed to play an important role in immune response to maintain tissue homeostasis by activating cellular signaling pathways and releasing inflammatory mediators in the injured tissue. Although acute inflammation can be considered protective, an uncontrolled inflammation may evolve to tissue damage, leading to chronic inflammatory diseases. Inflammation can be considered the major factor involved in the pathological progression of acute and chronic kidney diseases. Functional characteristics of this organ increase its vulnerability to developing various forms of injuries, including acute kidney injury (AKI) and chronic kidney disease (CKD). In view of translational research, several discoveries should be considered regarding the pathogenesis of the inflammatory process, which results in the validation of biomarkers for early detection of kidney diseases. Biomarkers enable the identification of proinflammatory mediators in kidney affections, based on laboratory research applied to clinical practice. Some inflammatory molecules can be useful biomarkers for the detection and diagnosis of kidney diseases, such as neutrophil gelatinase-associated lipocalin, kidney injury molecule-1 and interleukin 18.

Clinically translatable gold nanozymes with broad spectrum antioxidant and anti-inflammatory activity for alleviating acute kidney injury

Rationale: Acute kidney injury (AKI) is associated with aberrant generation of oxidative species and inflammation, leading to high mortality of in-hospitalized patients. Although N-acetylcysteine (NAC) showed positive effects in alleviating contrast-induced AKI, the clinical applications are strongly restrained due to the low bioavailability, low renal accumulation, short renal retention time, and high dosage-induced toxicity. Methods: We addressed the clinical dilemma of NAC by developing ultrasmall gold nanoclusters (1-2 nm) capped with NAC (denoted as Au NCs-NAC) as a nanozyme-based antioxidant defense system for AKI alleviation. Rhabdomyolysis-induced AKI mice model was developed, and the same dose of free NAC (as a control) and NAC onto Au NCs (Au NCs-NAC) was used for in vivo investigation of AKI restoration. Results: The as-developed gold nanozyme exhibited high bioavailability and good physicochemical stability as compared to NAC. Meanwhile, Au NCs-NAC showed broad-spectrum antioxidant activity of Au NCs-NAC, offering in vitro renoprotective effects, as well as macrophages by relieving inflammation under hydrogen peroxide or lipopolysaccharide stimulation. Notably, owing to the smaller size than kidney threshold (5.5 nm), Au NCs-NAC displayed preferential renal enrichment (< 2 h) and longer retention (> 24 h) in AKI mice as revealed by fluorescence imaging, thereby largely enhancing the restoration of renal function in AKI mice than free NAC by protecting the kidneys from oxidative injury and inflammation without systemic toxicity, as demonstrated by tissues staining, inflammatory cytokines and biomarkers detection, and mice survival rate. Conclusion: Owing to the synergistic anti-inflammatory/antioxidative effects, and enhanced bioavailability and renal accumulation/retention, Au NCs-NAC displayed far superior therapeutic performance than NAC alone. This work will facilitate the development of high-performance antioxidative nanoplatforms, as well as overcome the clinical limitations of small molecular drugs for AKI treatment and other inflammatory diseases.

Targeting Mitochondria and Metabolism in Acute Kidney Injury

Acute kidney injury (AKI) significantly contributes to morbidity and mortality in critically ill patients. AKI is also an independent risk factor for the development and progression of chronic kidney disease. Effective therapeutic strategies for AKI are limited, but emerging evidence indicates a prominent role of mitochondrial dysfunction and altered tubular metabolism in the pathogenesis of AKI. Therefore, a comprehensive, mechanistic understanding of mitochondrial function and renal metabolism in AKI may lead to the development of novel therapies in AKI. In this review, we provide an overview of current state of research on the role of mitochondria and tubular metabolism in AKI from both pre-clinical and clinical studies. We also highlight current therapeutic strategies which target mitochondrial function and metabolic pathways for the treatment of AKI.

Redox-Mediated Artificial Non-Enzymatic Antioxidant MXene Nanoplatforms for Acute Kidney Injury Alleviation

Acute kidney injury (AKI), as a common oxidative stress-related renal disease, causes high mortality in clinics annually, and many other clinical diseases, including the pandemic COVID-19, have a high potential to cause AKI, yet only rehydration, renal dialysis, and other supportive therapies are available for AKI in the clinics. Nanotechnology-mediated antioxidant therapy represents a promising therapeutic strategy for AKI treatment. However, current enzyme-mimicking nanoantioxidants show poor biocompatibility and biodegradability, as well as non-specific ROS level regulation, further potentially causing deleterious adverse effects. Herein, the authors report a novel non-enzymatic antioxidant strategy based on ultrathin Ti3 C2 -PVP nanosheets (TPNS) with excellent biocompatibility and great chemical reactivity toward multiple ROS for AKI treatment. These TPNS nanosheets exhibit enzyme/ROS-triggered biodegradability and broad-spectrum ROS scavenging ability through the readily occurring redox reaction between Ti3 C2 and various ROS, as verified by theoretical calculations. Furthermore, both in vivo and in vitro experiments demonstrate that TPNS can serve as efficient antioxidant platforms to scavenge the overexpressed ROS and subsequently suppress oxidative stress-induced inflammatory response through inhibition of NF-κB signal pathway for AKI treatment. This study highlights a new type of therapeutic agent, that is, the redox-mediated non-enzymatic antioxidant MXene nanoplatforms in treatment of AKI and other ROS-associated diseases.

Nanohybrids of Magnetically Intercalated Optical Metamaterials for Magnetic Resonance/Raman Imaging and In Situ Chemodynamic/Photothermal Therapy

Target-specific reactive oxygen species (ROS)-based cancer treatments with high therapeutic efficacy and minimal side effects have been identified recently as a potentially effective cancer management strategy. Herein, we report the fabrication of a targeted nanotheranostic agent built on an iron oxide nanoparticle-decorated graphene-gold hybrid [plasmonic magnetic nanoprobe (PMNP)] for self-guided magnetic resonance (MR)/surface-enhanced Raman scattering imaging and photothermal therapy (PTT)/chemodynamic therapy (CDT). In the presence of glutathione, which is abundant in the tumor environment, the iron oxide nanoparticles undergo in situ reduction, which in turn generates hydroxyl radicals via a Fenton reaction to realize targeted destruction of tumor cells. Moreover, the localized production of heat benefited from the near-infrared absorption of the PMNP accelerates the intratumoral ROS generation process, with a synergistic effect of CDT/PTT. Furthermore, the probe offers an accurate visualization of the intracellular localization of the material through SERS/MR dual imaging channels. In view of the advantages offered by the tumor-specific stimuli-responsive nature of the probe, the PMNP presents as an effective tool for cancer management.

Therapeutic hypothermia effect on asphyxial cardiac arrest-induced renal ischemia/reperfusion injury via change of Nrf2/HO-1 levels

The present study aimed to investigate the renoprotective effect of therapeutic hypothermia (TH) on renal ischemia-reperfusion injury (RI/RI) induced by asphyxial cardiac arrest (CA) in rats. A total of 48 male rats were randomly divided into five groups: i) Sham (n=6); ii) Normothermia + CA (Normo.) (n=14); iii) Normo. and 2 h of TH after return of spontaneous circulation (ROSC) (n=12); iv) Normo. and 4 h of TH after ROSC (n=9); and v) Normo. and 6 h of TH after ROSC (n=7). All rats except the Sham group underwent asphyxia CA and were sacrificed 1 day after ROSC. The survival rate increased from 42.8% in the Normo. group to 50, 66.6 and 85.7% in the groups with 2, 4 and 6 h of TH after CA, respectively. TH attenuated the histopathological changes of the renal tissues following ROSC and the levels of blood urea nitrogen, serum creatinine and malondialdehyde in renal tissues. On immunohistochemistry, the relative optical density of nuclear erythroid-related factor-2 (Nrf2) and heme oxygenase (HO-1) expression in renal tissues increased in the Normo. group compared with that in the Sham group and exhibited further significant increases at 6 h of TH after ROSC. In conclusion, TH attenuated renal injury and increased the expression of Nrf2 and HO-1 in a TH treatment time-dependent manner.

Hypoxic mesenchymal stem cells ameliorate acute kidney ischemia-reperfusion injury via enhancing renal tubular autophagy

BACKGROUND

Acute kidney injury (AKI) is an emerging global healthcare issue without effective therapy yet. Autophagy recycles damaged organelles and helps maintain tissue homeostasis in acute renal ischemia-reperfusion (I/R) injury. Hypoxic mesenchymal stem cells (HMSCs) represent an innovative cell-based therapy in AKI. Moreover, the conditioned medium of HMSCs (HMSC-CM) rich in beneficial trophic factors may serve as a cell-free alternative therapy. Nonetheless, whether HMSCs or HMSC-CM mitigate renal I/R injury via modulating tubular autophagy remains unclear.

METHODS

Renal I/R injury was induced by clamping of the left renal artery with right nephrectomy in male Sprague-Dawley rats. The rats were injected with either PBS, HMSCs, or HMSC-CM immediately after the surgery and sacrificed 48 h later. Renal tubular NRK-52E cells subjected to hypoxia-reoxygenation (H/R) injury were co-cultured with HMSCs or treated with HMSC-CM to assess the regulatory effects of HSMCs on tubular autophagy and apoptosis. The association of tubular autophagy gene expression and renal recovery was also investigated in patients with ischemic AKI.

RESULT

HMSCs had a superior anti-oxidative effect in I/R-injured rat kidneys as compared to normoxia-cultured mesenchymal stem cells. HMSCs further attenuated renal macrophage infiltration and inflammation, reduced tubular apoptosis, enhanced tubular proliferation, and improved kidney function decline in rats with renal I/R injury. Moreover, HMSCs suppressed superoxide formation, reduced DNA damage and lipid peroxidation, and increased anti-oxidants expression in renal tubular epithelial cells during I/R injury. Co-culture of HMSCs with H/R-injured NRK-52E cells also lessened tubular cell death. Mechanistically, HMSCs downregulated the expression of pro-inflammatory interleukin-1β, proapoptotic Bax, and caspase 3. Notably, HMSCs also upregulated the expression of autophagy-related LC3B, Atg5 and Beclin 1 in renal tubular cells both in vivo and in vitro. Addition of 3-methyladenine suppressed the activity of autophagy and abrogated the renoprotective effects of HMSCs. The renoprotective effect of tubular autophagy was further validated in patients with ischemic AKI. AKI patients with higher renal LC3B expression were associated with better renal recovery.

CONCLUSION

The present study describes that the enhancing effect of MSCs, and especially of HMCSs, on tissue autophagy can be applied to suppress renal tubular apoptosis and attenuate renal impairment during renal I/R injury in the rat. Our findings provide further mechanistic support to HMSCs therapy and its investigation in clinical trials of ischemic AKI.

Mitochondrial Metabolism in Acute Kidney Injury

The kidney is a highly metabolic organ that requires substantial adenosine triphosphate for the active transport required to maintain water and solute reabsorption. Aberrations in energy availability and energy utilization can lead to cellular dysfunction and death. Mitochondria are essential for efficient energy production. The pathogenesis of acute kidney injury is complex and varies with different types of injury. However, multiple distinct acute kidney injury syndromes share a common dysregulation of energy metabolism. Pathways of energy metabolism and mitochondrial dysfunction are emerging as critical drivers of acute kidney injury and represent new potential targets for treatment. This review shows the basic metabolic pathways that all cells depend on for life; describes how the kidney optimizes those pathways to meet its anatomic, physiologic, and metabolic needs; summarizes the importance of metabolic and mitochondrial dysfunction in acute kidney injury; and analyzes the mitochondrial processes that become dysregulated in acute kidney injury including mitochondrial dynamics, mitophagy, mitochondrial biogenesis, and changes in mitochondrial energy metabolism.

Physiological factors characterizing heat-vulnerable older adults: A narrative review

More frequent and intense periods of extreme heat (heatwaves) represent the most direct challenge to human health posed by climate change. Older adults are particularly vulnerable, especially those with common age-associated chronic health conditions (e.g., cardiovascular disease, hypertension, obesity, type 2 diabetes, chronic kidney disease). In parallel, the global population is aging and age-associated disease rates are on the rise. Impairments in the physiological responses tasked with maintaining homeostasis during heat exposure have long been thought to contribute to increased risk of health disorders in older adults during heatwaves. As such, a comprehensive overview of the provisional links between age-related physiological dysfunction and elevated risk of heat-related injury in older adults would be of great value to healthcare officials and policy makers concerned with protecting heat-vulnerable sectors of the population from the adverse health impacts of heatwaves. In this narrative review, we therefore summarize our current understanding of the physiological mechanisms by which aging impairs the regulation of body temperature, hemodynamic stability and hydration status. We then examine how these impairments may contribute to acute pathophysiological events common during heatwaves (e.g., heatstroke, major adverse cardiovascular events, acute kidney injury) and discuss how age-associated chronic health conditions may exacerbate those impairments. Finally, we briefly consider the importance of physiological research in the development of climate-health programs aimed at protecting heat-vulnerable individuals.

Selective inhibition of arginase-2 in endothelial cells but not proximal tubules reduces renal fibrosis

Fibrosis is the final common pathway in the pathophysiology of most forms of chronic kidney disease (CKD). As treatment of renal fibrosis still remains largely supportive, a refined understanding of the cellular and molecular mechanisms of kidney fibrosis and the development of novel compounds are urgently needed. Whether arginases play a role in the development of fibrosis in CKD is unclear. We hypothesized that endothelial arginase-2 (Arg2) promotes the development of kidney fibrosis induced by unilateral ureteral obstruction (UUO). Arg2 expression and arginase activity significantly increased following renal fibrosis. Pharmacologic blockade or genetic deficiency of Arg2 conferred kidney protection following renal fibrosis, as reflected by a reduction in kidney interstitial fibrosis and fibrotic markers. Selective deletion of Arg2 in endothelial cells (Tie2Cre/Arg2fl/fl) reduced the level of fibrosis after UUO. In contrast, selective deletion of Arg2 specifically in proximal tubular cells (Ggt1Cre/Arg2fl/fl) failed to reduce renal fibrosis after UUO. Furthermore, arginase inhibition restored kidney nitric oxide (NO) levels, oxidative stress, and mitochondrial function following UUO. These findings indicate that endothelial Arg2 plays a major role in renal fibrosis via its action on NO and mitochondrial function. Blocking Arg2 activity or expression could be a novel therapeutic approach for prevention of CKD.