Nox4 in renal diseases: An update

NOX4 mediates the renoprotection of remote ischemic preconditioning against acute kidney injury by inhibiting NF-κB signaling and tubular apoptosis

Acute kidney injury (AKI) is a clinical syndrome characterized by an abrupt loss of kidney function and is associated with increased morbidity and mortality. Remote ischemic preconditioning (rIPC) is a nonpharmacological intervention involving brief episodes of ischemia in distal tissues, which may provide protection from kidney injury, but its underlying mechanism remain elusive. In a previous study, we demonstrated that NOX4 can serve as a potential therapeutic target in AKI and is associated with the upregulation of inflammation and apoptosis. Therefore, we hypothesized that rIPC might attenuate AKI by inhibiting the NOX4-mediated NF-κB signaling pathway and apoptosis. In this study, we demonstrated that rIPC protected kidney function and pathological injury in lipopolysaccharide (LPS)-induced, cisplatin-induced and ischemic-reperfusion injury (IRI)-induced AKI mouse models. rIPC significantly inhibited the activation of NF-κB and tubular epithelial apoptosis in AKI mice, and hypoxic preconditioning (HPC) similarly suppressed NF-κB and apoptosis of TCMK-1 cells. Notably, rIPC intervention alone slightly increased/preconditioned NOX4 expression in control group mice, while substantially inhibiting NOX4 overexpression when the mice were subjected to AKI insults. Mechanistically, In LPS-stimulated TCMK-1 cells overexpressing NOX4, when treated with rIPC, the excessive activation of NF-κB and apoptosis was further alleviated. These findings demonstrated that rIPC is a potential therapeutic method against AKI and that NOX4 plays a central role in mediating the protective effects of rIPC through the inhibition of NF-κB signaling and tubular apoptosis.

Global research hotspots and trends in oxidative stress-related diabetic nephropathy: a bibliometric study

Background

Oxidative stress is widely acknowledged as a key pathogenic mechanism in diabetic nephropathy (DN). In recent years, the role of oxidative stress in DN has garnered increasing attention. However, no bibliometric analysis has yet been conducted on the relationship between oxidative stress and DN. This study aims to systematically analyze the relevant literature, identify trends in research, assess current hotspots, and predict future directions.

Methods

We retrieved literature related to oxidative stress and DN from the Web of Science Core Collection database. We analyzed data on publication volume, countries/regions, institutions, journals, keywords, and other relevant metrics using VOSviewer, the Bibliometrix R package, and CiteSpace.

Results

From 2014 to 2024, a total of 4076 publications related to oxidative stress and DN were published across 755 journals, showing a consistent upward trend each year. China and the United States are the leading contributors in this field and demonstrate close collaborative efforts. The top contributors by country, institution, journal, and author include: China (1919 publications), Jilin University and Central South University (69 publications each), BIOMEDICINE & PHARMACOTHERAPY (117 publications), and Prof. Sun Lin (33 publications). The most frequent keyword is "oxidative stress" (3683 occurrences). In the co-citation analysis, Alicic RZ's 2017 study was the most cited (144 citations). These findings highlight the critical importance of investigating the pathogenesis of DN from the oxidative stress perspective.

Conclusion

This study demonstrates a steady increase in research on oxidative stress in DN since 2014, highlighting its central role in the pathogenesis of DN. Future research should focus on the molecular mechanisms of oxidative stress in DN and explore its therapeutic potential, to provide new strategies for the prevention and treatment of DN.

Knockdown of Leucine-rich alpha-2-glycoprotein 1 alleviates renal ischemia-reperfusion injury by inhibiting NOX4-mediated apoptosis, inflammation, and oxidative stress

Renal ischemia-reperfusion (I/R) injury leads mainly to acute kidney injury. Leucine-rich alpha-2-glycoprotein 1 (LRG) is upregulated in kidney tissues of mice after renal I/R injury. However, its role in renal I/R injury has not been fully elucidated. A mouse model of renal I/R injury was constructed by unilateral renal pedicle clamping and reperfusion. Mice undergoing I/R procedures exhibited renal function impairment and increased LRG protein expression compared with mice receiving sham operations. Tail vein injection with lentivirus carrying shLRG decreased renal I/R injury-induced increase in caspase-3 activity, IL-1β and IL-18 concentrations, and ROS production. Furthermore, shRNA-mediated LRG knockdown in HK-2 cells protected against H/R-induced cell damage. LRG could upregulate the expression of NADPH oxidase 4 (NOX4). We also determined the increased NOX4 expression in kidney tissues of renal I/R-operated mice and H/R-treated HK-2 cells. NOX4 overexpression reversed the inhibitory role of LRG knockdown in HK-2 cell damage caused by H/R. Collectively, our findings demonstrate that LRG knockdown decreases the NOX4 expression, thereby alleviating renal I/R injury by inhibiting cell apoptosis, inflammation, and oxidative stress.

Nox4 is involved in acute kidney injury associated to intravascular hemolysis

Massive intravascular hemolysis occurs not unfrequently in many clinical conditions. Breakdown of erythrocytes promotes the accumulation of heme-derivates in the kidney, increasing oxidative stress and cell death, thus promoting acute kidney injury (AKI). NADPH oxidase 4 (Nox4) is a major source of reactive oxygen species (ROS) in the kidney, however it is unknown the role of Nox4 in hemolysis and whether inhibition of this enzyme may protect from heme-mediated injury. To answer these questions, we elicited intravascular hemolysis in wild type and Nox4 knockout mice. We also evaluated whether nephrotoxic effects of heme may be reduced by using Nox4 siRNA and pharmacologic inhibition with GKT137831, a Nox4 inhibitor, both in vivo and in cultured renal cells. Our results showed that induction of massive hemolysis elicited AKI characterized by loss of renal function, morphological alterations of the tubular epithelium and podocytes, oxidative stress, inflammation, mitochondrial dysfunction, blockade of autophagy and cell death. These pathological effects were significantly prevented in Nox4-deficient mice and in animals treated with GKT137831. In vitro studies showed that Nox4 disruption by specific siRNAs or Nox4 inhibitors declined heme-mediated ROS production and cell death. Our data identify Nox4 as a key enzyme involved in intravascular hemolysis-induced AKI. Thus, Nox4 inhibition may be a potential therapeutic approach to prevent renal damage in patients with severe hemolytic crisis.

Breaking boundaries in diabetic nephropathy treatment: design and synthesis of novel steroidal SGLT2 inhibitors

The activity of sodium glucose co-transporter 2 (SGLT2) has always been an important parameter influencing chronic kidney disease in type-2 diabetic patients. Herein, we have meticulously designed, synthesized, and evaluated several novel steroidal pyrimidine molecules that possess the capability to successfully bind to the SGLT2 protein and inhibit its activity, thereby remedying kidney-related ailments in diabetic patients. The lead steroidal pyrimidine compounds were selected after virtually screening from a library of probable N-heterocyclic steroidal scaffolds. A nano-catalyzed synthetic route was also explored for the synthesis of the steroidal pyrimidine analogs demonstrating an environmentally benign protocol. Extensive in vitro investigations encompassing SGLT2 screening assays and cell viability assessments were conducted on the synthesized compounds. Among the steroidal pyrimidine derivatives evaluated, compound 9a exhibited the highest SGLT2 inhibition activity and underwent further scrutiny. Western blot analysis was employed to determine the impact of 9a on inflammatory and fibrotic proteins, aiming to elucidate its mechanism of action. Additionally, in silico analyses were performed to illuminate the structural dynamics and molecular interaction mechanism of 9a. The overall investigation is crucial for advancing the development of the next generation of anti-diabetic drugs.

Tumor Microenvironment-Activated In Situ Synthesis of Peroxynitrite for Enhanced Chemodynamic Therapy

Chemodynamic therapy (CDT) can induce cancer cell death through hydroxyl radicals (·OH) generated from Fenton or Fenton-like reactions. Compared with traditional therapies, CDT effectively overcomes inevitable drug resistance and exhibits low side effects. However, clinical application still faces challenges, primarily due to insufficient ·OH generation and the short-lifetime of ·OH in vivo. To address these challenges, we developed a peroxynitrite (ONOO-)-based CDT nanodrug (DOX@PMOF) composed of MOF-199, NO donor (PArg), and nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) activator (doxorubicin, DOX). In DOX@PMOF, MOF-199 serves as both a carrier for loading DOX and a source of Cu+ for triggering CDT. Upon uptake by cancer cells, the high concentration of glutathione (GSH) reduces MOF-199 to Cu+, which then reacts with H2O2 to generate ·OH. Moreover, the released DOX upregulates NOX4 expression, leading to the elevated H2O2 level and thereby promoting a high-efficiency Fenton-like reaction for sufficient ·OH generation. Subsequently, PArg generates abundant NO in response to the tumor microenvironment, leading to a cascade of NO and ·OH for the in situ synthesis of ONOO-. ONOO- is more toxic and has a longer lifetime and diffusion distance than ·OH, resulting in a more effective CDT treatment. To further enhance the in vivo therapeutic effect, we coated DOX@PMOF with a homologous cell membrane to form an active tumor-targeting nanodrug (DOX@MPMOF), which has demonstrated the ability to effectively inhibit tumor growth and metastasis while exhibiting good biosafety.

The mineralocorticoid receptor in diabetic kidney disease

Diabetes mellitus is one of the leading causes of chronic kidney disease and its progression to end-stage kidney disease (ESKD). Diabetic kidney disease (DKD) is characterized by glomerular hypertrophy, hyperfiltration, inflammation, and the onset of albuminuria, together with a progressive reduction in glomerular filtration rate. This progression is further accompanied by tubulointerstitial inflammation and fibrosis. Factors such as genetic predisposition, epigenetic modifications, metabolic derangements, hemodynamic alterations, inflammation, and inappropriate renin-angiotensin-aldosterone system (RAAS) activity contribute to the onset and progression of DKD. In this context, decades of work have focused on glycemic and blood pressure reduction strategies, especially targeting the RAAS to slow disease progression. Although much of the work has focused on targeting angiotensin II, emerging data support that the mineralocorticoid receptor (MR) is integral in the development and progression of DKD. Molecular mechanisms linked to the underlying pathophysiological changes derived from MR activation include vascular endothelial and epithelial cell responses to oxidative stress and inflammation. These responses lead to alterations in the microcirculatory environment, the abnormal release of extracellular vesicles, gut dysbiosis, epithelial-mesenchymal transition, and kidney fibrosis. Herein, we present recent experimental and clinical evidence on the MR in DKD onset and progress along with new MR-based strategies for the treatment and prevention of DKD.

Acidic preconditioning induced intracellular acid adaptation to protect renal injury via dynamic phosphorylation of focal adhesion kinase-dependent activation of sodium hydrogen exchanger 1

BACKGROUND

Disruptions in intracellular pH (pHi) homeostasis, causing deviations from the physiological range, can damage renal epithelial cells. However, the existence of an adaptive mechanism to restore pHi to normalcy remains unclear. Early research identified H+ as a critical mediator of ischemic preconditioning (IPC), leading to the concept of acidic preconditioning (AP). This concept proposes that short-term, repetitive acidic stimulation can enhance a cell's capacity to withstand subsequent adverse stress. While AP has demonstrated protective effects in various ischemia-reperfusion (I/R) injury models, its application in kidney injury remains largely unexplored.

METHODS

An AP model was established in human kidney (HK2) cells by treating them with an acidic medium for 12 h, followed by a recovery period with a normal medium for 6 h. To induce hypoxia/reoxygenation (H/R) injury, HK2 cells were subjected to hypoxia for 24 h and reoxygenation for 1 h. In vivo, a mouse model of IPC was established by clamping the bilateral renal pedicles for 15 min, followed by reperfusion for 4 days. Conversely, the I/R model involved clamping the bilateral renal pedicles for 35 min and reperfusion for 24 h. Western blotting was employed to evaluate the expression levels of cleaved caspase 3, cleaved caspase 9, NHE1, KIM1, FAK, and NOX4. A pH-sensitive fluorescent probe was used to measure pHi, while a Hemin/CNF microelectrode monitored kidney tissue pH. Immunofluorescence staining was performed to visualize the localization of NHE1, NOX4, and FAK, along with the actin cytoskeleton structure in HK2 cells. Cell adhesion and scratch assays were conducted to assess cell motility.

RESULTS

Our findings demonstrated that AP could effectively mitigate H/R injury in HK2 cells. This protective effect and the maintenance of pHi homeostasis by AP involved the upregulation of Na+/H+ exchanger 1 (NHE1) expression and activity. The activity of NHE1 was regulated by dynamic changes in pHi-dependent phosphorylation of Focal Adhesion Kinase (FAK) at Y397. This process was associated with NOX4-mediated reactive oxygen species (ROS) production. Furthermore, AP induced the co-localization of FAK, NOX4, and NHE1 in focal adhesions, promoting cytoskeletal remodeling and enhancing cell adhesion and migration capabilities.

CONCLUSIONS

This study provides compelling evidence that AP maintains pHi homeostasis and promotes cytoskeletal remodeling through FAK/NOX4/NHE1 signaling. This signaling pathway ultimately contributes to alleviated H/R injury in HK2 cells.

A glycopolymersome strategy for 'drug-free' treatment of diabetic nephropathy

Diabetic nephropathy is a severe complication of diabetes. Treatment of diabetic nephropathy is an important challenge due to persistent hyperglycemia and elevated levels of reactive oxygen species (ROS) in the kidney. Herein, we designed a glycopolymersome that can treat type 2 diabetic nephropathy by effectively inhibiting hyperglycemia and ROS-associated diabetic nephropathy pathogenesis. The glycopolymersome is self-assembled from phenylboronic acid derivative-containing copolymer, poly(ethylene oxide)45-block-poly[(aspartic acid)13-stat-glucosamine24-stat-(phenylboronic acid)18-stat-(phenylboronic acid pinacol ester)3] [PEO45-b-P(Asp13-stat-GA24-stat-PBA18-stat-PAPE3)]. PBA segment can reversibly bind blood glucose or GA segment for long-term regulation of blood glucose levels; PAPE segment can scavenge excessive ROS for renoprotection. In vitro studies confirmed that the glycopolymersomes exhibit efficient blood glucose responsiveness within 2 h and satisfactory ROS-scavenging ability with 500 μM H2O2. Moreover, the glycopolymersomes display long-acting regulation of blood glucose levels in type 2 diabetic nephropathy mice within 32 h. Dihydroethidium staining revealed that these glycopolymersomes reduced ROS to normal levels in the kidney, which led to 61.7% and 76.6% reduction in creatinine and urea levels, respectively, along with suppressing renal apoptosis, collagen accumulation, and glycogen deposition in type 2 diabetic nephropathy mice. Notably, the polypeptide-based glycopolymersome was synthesized by ring-opening polymerization (ROP) of N-carboxyanhydrides (NCAs), thereby exhibiting favorable biodegradability. Overall, we proposed a new glycopolymersome strategy for 'drug-free' treatment of diabetic nephropathy, which could be extended to encompass the design of various multifunctional nanoparticles targeting diabetes and its associated complications.

Cannabidiol attenuates arsenic-induced nephrotoxicity via the NOX4 and NF-κB pathways in mice

Background and purpose

Cannabidiol (CBD) is a phenolic terpene compound with anticancer, antioxidant, anti-inflammatory, antibacterial, neuroprotective, and anticonvulsant properties. Since the effects of CBD on sodium arsenite (As)-induced nephrotoxicity have not been fully determined, this study investigated the effect of CBD on As-induced nephrotoxicity by evaluating the NOX4 and NF-kB pathways in mice.

Experimental approach

48 male mice were divided into six groups (8 each) including group 1, receiving saline for 14 days; group 2, receiving CBD (10 mg/kg, intraperitoneally) from the 7th to the 14th day; group 3, receiving As (10 mg/kg) for 14 days by gavage; and treatment groups 4-6, receiving CBD (2.5, 5, and 10 mg/kg, i.p.) 1.5 h before As (10 mg/kg by gavage, for 14 days) from the 7th to the 14th day. Mice were anesthetized after overnight fasting on day 15, and the blood sample was collected from their hearts. The level of antioxidants and pro-inflammatory factors, the expression of ROS and TNF-α, NF-kB, NOX4, iNOS, cleaved PARP, and caspase-3 proteins were measured and histological studies were performed.

Findings/Results

Exposure to As significantly increased kidney markers, oxidative stress, apoptosis, and inflammation in mice kidney tissue, and pretreatment with CBD reversed these changes. In addition, CBD significantly decreased the expression of NF-kB and NOX4, and the levels of pro-inflammatory factors and the expression of cleaved PARP and increased the level of antioxidants.

Conclusion and implications

CBD ameliorated As-induced nephrotoxicity related to inhibiting oxidative stress, inflammation, and apoptosis, potentially through the NF-kB/Nox4 pathway.

Efficacy of Trametinib in Alleviating Cisplatin-Induced Acute Kidney Injury: Inhibition of Inflammation, Oxidative Stress, and Tubular Cell Death in a Mouse Model

Cisplatin, a platinum-based chemotherapeutic, is effective against various solid tumors, but its use is often limited by its nephrotoxic effects. This study evaluated the protective effects of trametinib, an FDA-approved selective inhibitor of mitogen-activated protein kinase kinase 1/2 (MEK1/2), against cisplatin-induced acute kidney injury (AKI) in mice. The experimental design included four groups, control, trametinib, cisplatin, and a combination of cisplatin and trametinib, each consisting of eight mice. Cisplatin was administered intraperitoneally at a dose of 20 mg/kg to induce kidney injury, while trametinib was administered via oral gavage at 3 mg/kg daily for three days. Assessments were conducted 72 h after cisplatin administration. Our results demonstrate that trametinib significantly reduces the phosphorylation of MEK1/2 and extracellular signal-regulated kinase 1/2 (ERK1/2), mitigated renal dysfunction, and ameliorated histopathological abnormalities. Additionally, trametinib significantly decreased macrophage infiltration and the expression of pro-inflammatory cytokines in the kidneys. It also lowered lipid peroxidation by-products, restored the reduced glutathione/oxidized glutathione ratio, and downregulated NADPH oxidase 4. Furthermore, trametinib significantly inhibited both apoptosis and necroptosis in the kidneys. In conclusion, our data underscore the potential of trametinib as a therapeutic agent for cisplatin-induced AKI, highlighting its role in reducing inflammation, oxidative stress, and tubular cell death.

Potential biomarkers for immune monitoring after renal transplantation

Renal transplantation represents the foremost efficacious approach for ameliorating end-stage renal disease. Despite the current state of advanced renal transplantation techniques and the established postoperative immunosuppression strategy, a subset of patients continues to experience immune rejection during both the early and late postoperative phases, ultimately leading to graft loss. Consequently, the identification of immunobiomarkers capable of predicting the onset of immune rejection becomes imperative in order to facilitate early intervention strategies and enhance long-term prognoses. Upon reviewing the pertinent literature, we identified several indicators that could potentially serve as immune biomarkers to varying extents. These include the T1/T2 ratio, Treg/Th17 ratio, IL-10/TNF-α ratio, IL-33, IL-34, IL-6, IL-4, other cytokines, and NOX2/4.

Ameliorative effect of traditional polyherbal formulation on TNF-α, IL-1β and Caspase-3 expression in kidneys of wistar rats against sodium fluoride induced oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Sharbat-e-bazoori Motadil (SBM) is a polyherbal formulation that have been used for centuries as a part of the Unani system of medicine for renal disease.

AIM OF THE STUDY

The objective of this study was to explore and validate the nephroprotective potential of sugar-free SBM (SF-SBM) and its mechanisms of action against sodium fluoride (NaF)-induced nephrotoxicity in HEK-293 cells. Additionally, the study aimed to assess the quality control of SF-SBM and investigate its effects using an in vivo rat model with pattern recognition following oral administration of SF-SBM.

MATERIALS AND METHODS

The nephroprotective effect of SF-SBM was investigated using both an HEK-293 cell line and Wistar rats. Nephrotoxicity was induced in these models by administering NaF at a concentration of 600 ppm (parts per million) for a duration of seven days. The SF-SBM formulation was standardized using high-performance thin-layer chromatography (HPTLC) to assess the presence of marker compounds, namely gallic acid, quercetin, and ferulic acid. Metabolite characterization of SF-SBM was carried out using ultra-high-performance liquid chromatography mass spectrometry (UPLC-MS) with a monolithic capillary silica-based C18 column. This analytical technique allowed for the identification of bioactive substances and verification of the identified markers. Acute toxicity of SF-SBM was evaluated in Wistar rats by administering a single oral dose of 2000 mg/kg of SF-SBM. The nephroprotective efficacy of SF-SBM was further assessed at low (LD), medium (MD) and high (HD) doses of 32.1, 64.2, and 128.4 mg/kg, respectively, administered orally. Nephrotoxicity was induced in Wistar rats by adding NaF to their drinking water for seven days. Biochemical and urine markers were analyzed to evaluate the antioxidant, inflammatory, and apoptotic potential of SF-SBM. Additionally, histopathological analysis and immunohistochemical alterations in the expression of caspase-3 and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-4 (NOX-4) in kidney tissue were performed to confirm the findings of the in vivo experiments. Furthermore, in vivo pattern recognition of SF-SBM metabolites, identified through GC-MS metabolomics, and in-silico docking analysis of major metabolites in plasma were conducted to gain further insights.

RESULT

Phytochemical analysis using HPTLC, TLC-bioautography, and UPLC-MS revealed the presence of several bioactive constituents in SF-SBM, including ferulic acid, gallic acid (GA), ellagic acid, quercetin, and apigenin. These compounds exhibit diverse pharmacological properties. In vitro studies demonstrated the protective effect of SF-SBM on HEK-293 cell line against nephrotoxicity. The acute toxicity study of SF-SBM at a dose of 2000 mg/kg showed no mortality or signs of toxicity throughout the 14-day observation period. In the in vivo studies, administration of NaF resulted in significant elevation (P < 0.001) of biochemical and urine parameters, indicating oxidative, inflammatory, and apoptotic stress. Histopathological examination revealed severe depletion of Bowman's capsule, and immunohistochemistry demonstrated negative immunostaining for caspase-3 and reduced NOX-4 reactions. Pre-treatment with SF-SBM significantly attenuated the elevated biochemical and urine markers, restored the antioxidant enzyme levels (such as SOD, CAT, GSH, GPx and NO), and regulated the expression of inflammatory cytokines (TNF-α, IL-1β, CASP-3) in kidney tissue at doses of SF-SBM-MD (64.2 mg/kg) and SF-SBM-HD (128.4 mg/kg), showing comparable results to those of α-Ketoanalogue. Histopathological assessment demonstrated improvements in tissue damage. Pattern recognition analysis of SF-SBM identified the presence of 56 metabolites at different time intervals. Additionally, in-silico studies revealed strong interactions of SF-SBM with a binding energy of -6.5 and -5.6 kcal for 4C2N.

CONCLUSION

The phytoconstituents present in SF-SBM play a crucial role in its nephroprotective action by acting as potent antioxidants and reducing proinflammatory and apoptotic damage in rat cells. This indicates that SF-SBM has promising potential for the treatment of nephrotoxicity.

Folic acid antioxidant supplementation to binge drinking adolescent rats improves hydric-saline balance and blood pressure, but fails to increase renal NO availability and glomerular filtration rate

Binge drinking (BD) is an especially pro-oxidant pattern of alcohol consumption, particularly widespread in the adolescent population. In the kidneys, it affects the glomerular filtration rate (GFR), leading to high blood pressure. BD exposure also disrupts folic acid (FA) homeostasis and its antioxidant properties. The aim of this study is to test a FA supplementation as an effective therapy against the oxidative, nitrosative, and apoptotic damage as well as the renal function alteration occurred after BD in adolescence. Four groups of adolescent rats were used: control, BD (exposed to intraperitoneal alcohol), control FA-supplemented group and BD FA-supplemented group. Dietary FA content in control groups was 2 ppm, and 8 ppm in supplemented groups. BD provoked an oxidative imbalance in the kidneys by dysregulating antioxidant enzymes and increasing the enzyme NADPH oxidase 4 (NOX4), which led to an increase in caspase-9. BD also altered the renal nitrosative status affecting the expression of the three nitric oxide (NO) synthase (NOS) isoforms, leading to a decrease in NO levels. Functionally, BD produced a hydric-electrolytic imbalance, a low GFR and an increase in blood pressure. FA supplementation to BD adolescent rats improved the oxidative, nitrosative, and apoptotic balance, recovering the hydric-electrolytic equilibrium and blood pressure. However, neither NO levels nor GFR were recovered, showing in this study for the first time that NO availability in the kidneys plays a crucial role in GFR regulation that the antioxidant effects of FA cannot repair.

The role of apoptosis and oxidative stress in the pathophysiology of Acanthamoeba spp. infection in the kidneys of hosts with different immunological status

BACKGROUND

Acanthamoeba spp. are opportunistic pathogens that cause inflammation, mostly in the brain, lungs and cornea. Recent reports indicate kidney dysfunction in hosts with systemic acanthamoebiasis. The aim of the study was to analyze the gene expression and protein concentration of NADPH oxidase 2 and 4 (NOX2 and NOX4, respectively) and nuclear erythroid 2-related factor (Nrf2) in the kidneys of hosts with systemic acanthamoebiasis. We also aimed to determine the protein and gene expressions of Bcl2, Bax, caspases 3 and 9.

METHODS

 Mice were divided into four groups based on their immunological status and Acanthamoeba sp. infection: A, immunocompetent Acanthamoeba sp.-infected mice; AS, immunosuppressed Acanthamoeba sp.- infected mice; C, immunocompetent uninfected mice; CS, immunosuppressed uninfected mice. NOX2, NOX4 and Nrf2 were analyzed by quantitative reverse transcription PCR (qRT-PCR) and ELISA methods, while pro-apoptotic and anti-apoptotic proteins (Bax and Bcl-2, respectively), Cas9, Cas3 were analyzed by qRT-PCR and western blot methods.  RESULTS: Increased gene expression and/or protein concentration of NOX2 and NOX4 were found in both immunocompetent and immunosuppressed mice infected with Acanthamoeba sp. (groups A and AS, respectively). Gene expression and/or protein concentration of Nrf2 were higher in group A than in control animals. Compared to control mice, in the AS group the expression of the Nrf2 gene was upregulated while the concentration of Nrf2 protein was decreased. Additionally in A group, higher gene and protein expression of Bcl-2, and lower gene as well as protein expression of Bax, caspases 3 and 9 were noted. In contrast, the AS group showed lower gene and protein expression of Bcl-2, and higher gene as well as protein expression of Bax, caspases 3 and 9.

CONCLUSIONS

This study is the first to address the mechanisms occurring in the kidneys of hosts infected with Acanthamoeba sp. The contact of Acanthamoeba sp. with the host cell surface and/or the oxidative burst caused by elevated levels of NOXs lead to an antioxidant response enhanced by the Nrf2 pathway. Acanthamoeba sp. have various strategies concerning apoptosis. In immunocompetent hosts, amoebae inhibit the apoptosis of kidney cells, and in immunosuppressed hosts, they lead to increased apoptosis by the intrinsic pathway and thus to a more severe course of the disease.

Comprehensive analysis of the relationship between xanthine oxidoreductase activity and chronic kidney disease

Chronic kidney disease (CKD) is a common disease that seriously endangers human health. However, the potential relationship between xanthine oxidoreductase (XOR) activity and CKD remains unclear. In this study, we used clinical data, CKD datasets from the Gene Expression Omnibus database, and untargeted metabolomics to explain the relationship between XOR activity and CKD. First, XOR activity showed high correlation with the biomarkers of CKD, such as serum creatinine, blood urea nitrogen, uric acid, and estimated glomerular filtration rate. Then, we used least absolute shrinkage and selection operator logical regression algorithm and random forest algorithm to screen CKD molecular markers from differentially expressed genes, and the results of qRT-PCR of XDH, KOX-1, and ROMO1 were in accordance with the results of bioinformatics analyses. In addition, untargeted metabolomics analysis revealed that the purine metabolism pathway was significantly enriched in CKD patients in the simulated models of kidney fibrosis.

COL4A3 Mutation Induced Podocyte Apoptosis by Dysregulation of NADPH Oxidase 4 and MMP-2

INTRODUCTION

Podocyte apoptosis is a common mechanism driving progression in Alport syndrome (AS). This study aimed to investigate the mechanism of podocyte apoptosis caused by COL4A3 mutations.

METHODS

We recruited patients with autosomal dominant AS (ADAS). Patients with minimal change disease (MCD) were recruited as controls. Microarray analysis was carried out on isolated glomeruli from the patients and validated. Then, corresponding mutant human podocytes (p.C1616Y) and 129 mice (p.C1615Y, the murine homolog to the human p.C1616Y) were constructed. The highest differentially expressed genes (DEGs) from microarray analysis were validated in transgenic mice and podocytes before and after administration of MMP-2 inhibitor (SB-3CT) and NOX4 inhibitor (GKT137831). We further validated NOX4/MMP-2/apoptosis pathway by real-time polymerase chain reaction (PCR), immunohistochemistry, and western blot in renal tissues from the ADAS patients.

RESULTS

Using microarray analysis, we observed that DEGs, including NOX4/H2O2, MMP-2, and podocyte apoptosis-related genes were significantly upregulated. These genes were validated by real-time PCR, histologic analysis, and western blot in corresponding mutant human podocyte (p.C1616Y) and/or mice models (p.C1615Y). Moreover, we found podocyte apoptosis was abrogated and MMP-2 expression was down-regulated both in vivo and in vitro by NOX4 inhibition, urinary albumin-to-creatinine ratio, 24-hour proteinuria; and renal pathologic lesion was attenuated by NOX4 inhibition in vivo. Furthermore, podocyte apoptosis was attenuated whereas NOX4 expression remained the same by inhibition of MMP-2 both in vivo and in vitro.

CONCLUSION

These results indicated that NOX4 might induce podocyte apoptosis through the regulation of MMP-2 in patients with COL4A3 mutations. Our findings provided new insights into the mechanism of ADAS.

Oxalate (dys)Metabolism: Person-to-Person Variability, Kidney and Cardiometabolic Toxicity

Oxalate is a metabolic end-product whose systemic concentrations are highly variable among individuals. Genetic (primary hyperoxaluria) and non-genetic (e.g., diet, microbiota, renal and metabolic disease) reasons underlie elevated plasma concentrations and tissue accumulation of oxalate, which is toxic to the body. A classic example is the triad of primary hyperoxaluria, nephrolithiasis, and kidney injury. Lessons learned from this example suggest further investigation of other putative factors associated with oxalate dysmetabolism, namely the identification of precursors (glyoxylate, aromatic amino acids, glyoxal and vitamin C), the regulation of the endogenous pathways that produce oxalate, or the microbiota's contribution to oxalate systemic availability. The association between secondary nephrolithiasis and cardiovascular and metabolic diseases (hypertension, type 2 diabetes, and obesity) inspired the authors to perform this comprehensive review about oxalate dysmetabolism and its relation to cardiometabolic toxicity. This perspective may offer something substantial that helps advance understanding of effective management and draws attention to the novel class of treatments available in clinical practice.

Eupatilin Ameliorates Lipopolysaccharide-Induced Acute Kidney Injury by Inhibiting Inflammation, Oxidative Stress, and Apoptosis in Mice

Acute kidney injury (AKI) is a common complication of sepsis. Eupatilin (EUP) is a natural flavone with multiple biological activities and has beneficial effects against various inflammatory disorders. However, whether EUP has a favorable effect on septic AKI remains unknown. Here, we examined the effect of EUP on lipopolysaccharide (LPS)-evoked AKI in mice. LPS-evoked renal dysfunction was attenuated by EUP, as reflected by reductions in serum creatinine and blood urea nitrogen levels. LPS injection also induced structural damage such as tubular cell detachment, tubular dilatation, brush border loss of proximal tubules, and upregulation of tubular injury markers. However, EUP significantly ameliorated this structural damage. EUP decreased serum and renal cytokine levels, prevented macrophage infiltration, and inhibited mitogen-activated protein kinase and NF-κB signaling cascades. Lipid peroxidation and DNA oxidation were increased after LPS treatment. However, EUP mitigated LPS-evoked oxidative stress through downregulation of NPDPH oxidase 4 and upregulation of antioxidant enzymes. EUP also inhibited p53-mediated apoptosis in LPS-treated mice. Therefore, these results suggest that EUP ameliorates LPS-evoked AKI through inhibiting inflammation, oxidative stress, and apoptosis.

Perfluorooctane sulfonate-induced apoptosis in kidney cells by triggering the NOX4/ROS/JNK axis and antagonism of cannabidiol

Perfluorooctane sulfonate (PFOS) is one of the persistent organic pollutants (POPs), which can cause severe nephrotoxicity in mammals. Cannabinol (CBD), a nonpsychoactive cannabinoid obtained from the cannabis plant, has attracted attention in recent years for its excellent antioxidant properties. NADPH oxidase 4 (NOX4) has an important effect in supporting normal renal physiological function. The potential mechanisms of PFOS nephrotoxicity and whether CBD can prevent renal damage caused by PFOS remain unclear. This work aimed to study the mechanisms of PFOS-induced kidney damage and the protective role of CBD against PFOS-induced kidney damage. We demonstrated that PFOS led to renal insufficiency and structural damage in mice, induced overexpression of NOX4 and the onset of oxidative stress, and activated apoptosis of the mitochondrial pathway via the JNK signaling pathway. However, treatment with CBD reversed these changes. For further investigation of the potential mechanism of PFOS-induced renal cell apoptosis, the expression of NOX4 was inhibited in vitro experiments using Apocynin, an effective NOX4 inhibitor. The outcomes showed that PFOS-induced ROS production and JNK signaling pathway activation and apoptosis in human embryonic kidney (HEK293) cells were significantly reduced after inhibition of NOX4. This suggests that PFOS-induced NOX4 overexpression serves as an upstream event for JNK pathway activation. In conclusion, the findings suggest that PFOS induces apoptosis in renal cells via the NOX4/ROS/JNK pathway. Meanwhile, CBD alleviated PFOS-induced renal apoptosis through the inhibition of NOX4/ROS/JNK axis activation.

The selective NOX4 inhibitor GLX7013159 decreases blood glucose concentrations and human beta-cell apoptotic rates in diabetic NMRI nu/nu mice transplanted with human islets

NADPH oxidase 4 (NOX4) inhibition has been reported to mitigate diabetes-induced beta-cell dysfunction and improve survival in vitro, as well as counteract high-fat diet-induced glucose intolerance in mice. We investigated the antidiabetic effects of the selective NOX4 inhibitor GLX7013159 in vivo in athymic diabetic mice transplanted with human islets over a period of 4 weeks. The GLX7013159-treated mice achieved lower blood glucose and water consumption throughout the treatment period. Furthermore, GLX7013159 treatment resulted in improved insulin and c-peptide levels, better insulin secretion capacity, as well as in greatly reduced apoptotic rates of the insulin-positive human cells, measured as colocalization of insulin and cleaved caspase-3. We conclude that the antidiabetic effects of NOX4 inhibition by GLX7013159 are observed also during a prolonged study period in vivo and are likely to be due to an improved survival and function of the human beta-cells.

Diosgenin Inhibits ROS Generation by Modulating NOX4 and Mitochondrial Respiratory Chain and Suppresses Apoptosis in Diabetic Nephropathy

Diosgenin (DIO) is a dietary steroid sapogenin possessing multiple biological functions, such as the amelioration of diabetes. However, the remission effect of DIO on diabetic nephropathy (DN) underlying oxidative stress and cell apoptosis remains unclear. Here, the effect of DIO on ROS generation and its induced cell apoptosis was studied in vitro and in vivo. Renal proximal tubular epithelial (HK-2) cells were treated with DIO (1, 2, 4 µM) under high glucose (HG, 30 mM) conditions. DN rats were induced by a high-fat diet combined with streptozotocin, followed by administration of DIO for 8 weeks. Our data suggested that DIO relieved the decline of HK-2 cell viability and renal pathological damage in DN rats. DIO also relieved ROS (O2- and H2O2) production. Mechanistically, DIO inhibited the expression of NOX4 and restored mitochondrial respiratory chain (MRC) complex I-V expressions. Further, DIO inhibited mitochondrial apoptosis by ameliorating mitochondrial membrane potential (MtMP) and down-regulating the expressions of CytC, Apaf-1, caspase 3, and caspase 9, while up-regulating Bcl2 expression. Moreover, the ER stress and its associated cell apoptosis were inhibited through decreasing PERK, p-PERK, ATF4, IRE1, p-CHOP, and caspase 12 expressions. Collectively, DIO inhibited ROS production by modulating NOX4 and MRC complexes, which then suppressed apoptosis regulated by mitochondria and ER stress, thereby attenuating DN.

The Geroprotective Drug Candidate CMS121 Alleviates Diabetes, Liver Inflammation, and Renal Damage in db/db Leptin Receptor Deficient Mice

db/db mice, which lack leptin receptors and exhibit hyperphagia, show disturbances in energy metabolism and are a model of obesity and type 2 diabetes. The geroneuroprotector drug candidate CMS121 has been shown to be effective in animal models of Alzheimer's disease and aging through the modulation of metabolism. Thus, the hypothesis was that CMS121 could protect db/db mice from metabolic defects and thereby reduce liver inflammation and kidney damage. The mice were treated with CMS121 in their diet for 6 months. No changes were observed in food and oxygen consumption, body mass, or locomotor activity compared to control db/db mice, but a 5% reduction in body weight was noted. Improved glucose tolerance and reduced HbA1c and insulin levels were also seen. Blood and liver triglycerides and free fatty acids decreased. Improved metabolism was supported by lower levels of fatty acid metabolites in the urine. Markers of liver inflammation, including NF-κB, IL-18, caspase 3, and C reactive protein, were lowered by the CMS121 treatment. Urine markers of kidney damage were improved, as evidenced by lower urinary levels of NGAL, clusterin, and albumin. Urine metabolomics studies provided further evidence for kidney protection. Mitochondrial protein markers were elevated in db/db mice, but CMS121 restored the renal levels of NDUFB8, UQCRC2, and VDAC. Overall, long-term CMS121 treatment alleviated metabolic imbalances, liver inflammation, and reduced markers of kidney damage. Thus, this study provides promising evidence for the potential therapeutic use of CMS121 in treating metabolic disorders.

Nanodrugs alleviate acute kidney injury: Manipulate RONS at kidney

Currently, there are no clinical drugs available to treat acute kidney injury (AKI). Given the high prevalence and high mortality rate of AKI, the development of drugs to effectively treat AKI is a huge unmet medical need and a research hotspot. Although existing evidence fully demonstrates that reactive oxygen and nitrogen species (RONS) burst at the AKI site is a major contributor to AKI progression, the heterogeneity, complexity, and unique physiological structure of the kidney make most antioxidant and anti-inflammatory small molecule drugs ineffective because of the lack of kidney targeting and side effects. Recently, nanodrugs with intrinsic kidney targeting through the control of size, shape, and surface properties have opened exciting prospects for the treatment of AKI. Many antioxidant nanodrugs have emerged to address the limitations of current AKI treatments. In this review, we systematically summarized for the first time about the emerging nanodrugs that exploit the pathological and physiological features of the kidney to overcome the limitations of traditional small-molecule drugs to achieve high AKI efficacy. First, we analyzed the pathological structural characteristics of AKI and the main pathological mechanism of AKI: hypoxia, harmful substance accumulation-induced RONS burst at the renal site despite the multifactorial initiation and heterogeneity of AKI. Subsequently, we introduced the strategies used to improve renal targeting and reviewed advances of nanodrugs for AKI: nano-RONS-sacrificial agents, antioxidant nanozymes, and nanocarriers for antioxidants and anti-inflammatory drugs. These nanodrugs have demonstrated excellent therapeutic effects, such as greatly reducing oxidative stress damage, restoring renal function, and low side effects. Finally, we discussed the challenges and future directions for translating nanodrugs into clinical AKI treatment.

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AKI is a common clinical acute syndrome with high morbidity and mortality but without effective clinical drug available.

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Hypoxia and accumulation of toxic substances are key pathological features of various heterogeneous AKI.

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Excessive RONS is the core of the pathological mechanism of AKI.

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The development of nanodrugs is expected to achieve successful treatment in AKI.

(Pro)Renin Receptor Decoy Peptide PRO20 Protects against Oxidative Renal Damage Induced by Advanced Oxidation Protein Products

Chronic kidney disease (CKD) is associated with advanced oxidation protein products (AOPPs). A recent study has shown that AOPP-induced renal tubular injury is mediated by the (pro)renin receptor (PRR). However, it is unclear whether the PRR decoy inhibitor PRO20 can protect against renal damage related to AOPPs in vivo. In this study, we examined the role of the PRR in rats with AOPP-induced renal oxidative damage. Male SD rats were subjected to unilateral nephrectomy, and after a four-day recuperation period, they were randomly divided into four groups (n = 6/group) for four weeks: control (CTR), unmodified rat serum albumin (RSA, 50 mg/kg/day via tail-vein injection), AOPPs-RSA (50 mg/kg/day via tail-vein injection), and AOPPs-RSA + PRO20 (50 mg/kg/day via tail-vein injection + 500 μg/kg/day via subcutaneous injection) groups. PRO20 was administered 3 days before AOPPs-RSA injection. Renal histopathology evaluation was performed by periodic acid–Schiff (PAS) staining, and biochemical parameters related to renal injury and oxidative stress biomarkers were evaluated. The expression of related indicators was quantified by RT-qPCR and immunoblotting analysis. In the results, rats in the AOPPs-RSA group exhibited higher levels of albuminuria, inflammatory cell infiltration, and tubular dilation, along with upregulation of oxidative stress, profibrotic and proinflammatory factors, and elevation of AOPP levels. Meanwhile, in the PRO20 group, these were significantly reduced. Moreover, the levels of almost all components of the renin-angiotensin system (RAS) and Nox4-dependent H2O2 production in urine and the kidneys were elevated by AOPPs-RSA, while they were suppressed by PRO20. Furthermore, AOPPs-RSA rats showed elevated kidney expression of the PRR and soluble PRR (sPRR) and increased renal excretion of sPRR. In summary, these findings suggest that PRR inhibition may serve as a protective mechanism against AOPP-induced nephropathy by inhibiting the intrarenal RAS and Nox4-derived H2O2 mechanisms.

Antioxidant, Antiapoptotic, and Anti-Inflammatory Effects of Hesperetin in a Mouse Model of Lipopolysaccharide-Induced Acute Kidney Injury

Sepsis is a severe inflammatory condition that can cause organ dysfunction, including acute kidney injury (AKI). Hesperetin is a flavonoid aglycone that has potent antioxidant and anti-inflammatory properties. However, the effect of hesperetin on septic AKI has not yet been fully investigated. This study examined whether hesperetin has a renoprotective effect on lipopolysaccharide (LPS)-induced septic AKI. Hesperetin treatment ameliorated histological abnormalities and renal dysfunction in LPS-injected mice. Mechanistically, hesperetin attenuated LPS-induced oxidative stress, as evidenced by the suppression of lipid and DNA oxidation. This beneficial effect of hesperetin was accompanied by downregulation of the pro-oxidant NADPH oxidase 4, restoration of glutathione levels, and activation of antioxidant enzymes. This flavonoid compound also inhibited apoptotic cell death via suppression of p53-dependent caspase-3 pathway. Furthermore, hesperetin alleviated Toll-like receptor 4-mediated cytokine production and macrophage infiltration. Our findings suggest that hesperetin ameliorates LPS-induced renal structural and functional injury through suppressing oxidative stress, apoptosis, and inflammation.

Impact of magnesium sulfate therapy in improvement of renal functions in high fat diet-induced diabetic rats and their offspring

The role of magnesium sulfate (MgSO₄) administration to prevent diabetic nephropathy (DN) by reducing insulin resistance (IR) and the relationship of this action with gender and the expression of NOX4 and ICAM1 genes in the parents and their offspring were studied. Males and females rat, and their pups were used. Type 2 diabetes induced by high-fat diet (HFD) administration and a low dose of streptozotocin. Animals were divided into the: non-treated diabetic (DC), the diabetic group received insulin (Ins), and the diabetic group received MgSO₄. Two groups of parents received just a normal diet (NDC). Following each set of parents for 16 weeks and their pups for 4 months, while eating normally. We assessed the amount of water consumed, urine volume, and blood glucose level. The levels of glucose, albumin, and creatinine in the urine were also measured, as well as the amounts of sodium, albumin, and creatinine in the serum. Calculations were made for glomerular filtration rate (GFR) and the excretion rates of Na and glucose fractions (FE Na and FE G, respectively). The hyperinsulinemic-euglycemic clamp was done. NOX4 and ICAM1 gene expressions in the kidney were also measured. MgSO₄ or insulin therapy decreased blood glucose, IR, and improved GFR, FE Na, and FE G in both parents and their offspring compared to D group. MgSO₄ improved NOX4 and ICAM1 gene expressions in the parents and their offspring compared to D group. Our results indicated that MgSO₄ could reduce blood glucose levels and insulin resistance, and it could improve kidney function.

Prevention of nephrotoxicity induced by amikacin: The role of misoprostol, A prostaglandin E1 analogue

Amikacin (AK) is an aminoglycoside that is widely used to treat life-threatening Gram-negative infections, especially in intensive care units. Despite its wide clinical indications, AK causes serious side effects such as kidney toxicity. AK was found to lead to tissue damage primarily through apoptosis and oxidative stress. Therefore, it was investigated whether misoprostol (MP), which has antioxidant and antiapoptotic properties, had a beneficial effect on kidney damage caused by AK. It was observed that kidney injury molecule-1 (KIM-1) mRNA, blood urea nitrogen (BUN), creatinine (Cr), NADPH oxidase-4 (NOX-4) and Caspase-3 (CAS-3) levels increased in the AK-treated group in comparison with the control group, while uric acid, albumin, and total protein levels were decreased. In rats that were treated with AK+MP, the levels of KIM-1 mRNA, BUN, Cr, NOX-4 and CAS-3 were significantly decreased in comparison with the AK group, while uric acid, albumin and total protein levels increased. According to the obtained results, MP was found to be quite effective in the protection of kidneys from the toxic effects of AK.

A natural products solution to diabetic nephropathy therapy

Diabetic nephropathy is one of the most common complications in diabetes. It has been shown to be the leading cause of end-stage renal disease. However, due to their complex pathological mechanisms, effective therapeutic drugs other than angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), which have been used for 20 years, have not been developed so far. Recent studies have shown that diabetic nephropathy is characterized by multiple signalling pathways and multiple targets, including inflammation, apoptosis, pyroptosis, autophagy, oxidative stress, endoplasmic reticulum stress and their interactions. It definitely exacerbates the difficulty of therapy, but at the same time it also brings out the chance for natural products treatment. In the most recent two decades, a large number of natural products have displayed their potential in preclinical studies and a few compounds are under invetigation in clinical trials. Hence, many compounds targeting these singals have been emerged as a comprehensive blueprint for treating strategy of diabetic nephropathy. This review focuses on the cellular and molecular mechanisms of natural prouducts that alleviate this condition, including preclinical studies and clinical trials, which will provide new insights into the treatment of diabetic nephropathy and suggest novel ideas for new drug development.

Protective Effects of Orexin A in a Murine Model of Cisplatin-Induced Acute Kidney Injury

Cisplatin is a chemotherapeutic agent widely used in the treatment of various cancers, but its application is often limited due to complications such as acute kidney injury (AKI). Orexins are hypothalamic neuropeptides that modulate the sleep-wake cycle, neuroendocrine function, and the autonomic nervous system. Emerging evidence suggests that orexin A (OXA) has anti-inflammatory and neuroprotective effects in animal models of neuroinflammatory diseases of the central nervous system. However, the effect of OXA on kidney diseases has not been examined. Here, we investigated whether OXA has a protective effect in a murine model of cisplatin-induced AKI. Intraperitoneal administration of OXA ameliorated renal dysfunction, and histological abnormalities in mice injected with cisplatin. OXA inhibited cisplatin-induced oxidative stress through the modulation of prooxidant and antioxidant enzymes. This peptide reduced apoptotic cell death by inhibiting the p53-mediated pathway in mice injected with cisplatin. OXA also alleviated cisplatin-induced cytokine production and macrophage infiltration into injured kidneys. Taken together, these results showed that OXA ameliorates cisplatin-induced AKI via antioxidant, anti-apoptotic, and anti-inflammatory actions. This peptide could be a potential therapeutic agent for cisplatin-induced AKI.

Sirtuin 7 mitigates renal ferroptosis, fibrosis and injury in hypertensive mice by facilitating the KLF15/Nrf2 signaling

Hypertension is one of the leading causes of chronic kidney disease characterized with renal fibrosis. This study aimed to investigate roles and mechanisms of sirtuin 7 (SIRT7) in hypertensive renal injury. Mini-pumps were implanted to male C57BL/6 mice to deliver angiotensin (Ang) Ⅱ (1.5 mg/kg/d) or saline for 2 weeks. Ang Ⅱ infusion resulted in marked increases in systolic blood pressure levels, renal ferroptosis and interstitial fibrosis in hypertensive mice, concomitantly with downregulated SIRT7 and Krüppel-like factor 15 (KLF15) levels. Notably, administration of recombinant adeno-associated virus-SIRT7 or ferroptosis inhibitor ferrostatin-1 effectively mitigated Ang Ⅱ-triggered renal ferroptosis, epithelial-mesenchymal transition (EMT), interstitial fibrosis, renal functional and structural injury in hypertensive mice by blunting the KIM-1/NOX4 signaling and enforcing the KLF15/Nrf2 and xCT/GPX4 signaling, respectively. In primary cultured mouse renal tubular epithelial cells (TECs), Ang Ⅱ pretreatment led to repressed SIRT7 expression and augmented ferroptosis as well as partial EMT, which were substantially antagonized by rhSIRT7 or ferrostatin-1 administration. Additionally, both Nrf2 inhibitor ML385 and KLF15 siRNA strikingly abolished the rhSIRT7-mediated beneficial roles in mouse renal TECs in response to Ang Ⅱ with reduced expression of Nrf2, xCT and GPX4. More importantly, ML385 administration remarkably amplified Ang Ⅱ-mediated ROS generation, lipid peroxidation and ferroptosis in renal TECs, which were significantly reversed by ferrostatin-1. In conclusion, SIRT7 alleviates renal ferroptosis, lipid peroxidation, and partial EMT under hypertensive status by facilitating the KLF15/Nrf2 signaling, thereby mitigating renal fibrosis, injury and dysfunction. Targeting SIRT7 signaling serves as a promising strategy for hypertension and hypertensive renal injury.

Polydatin Ameliorates High Fructose-Induced Podocyte Oxidative Stress via Suppressing HIF-1α/NOX4 Pathway

Long-term high fructose intake drives oxidative stress, causing glomerular podocyte injury. Polydatin, isolated from Chinese herbal medicine Polygonum cuspidatum, is used as an antioxidant agent that protects kidney function. However, it remains unclear how polydatin prevents oxidative stress-driven podocyte damage. In this study, polydatin attenuated high fructose-induced high expression of HIF-1α, inhibited NOX4-mediated stromal cell-derived factor-1α/C-X-C chemokine receptor type 4 (SDF-1α/CXCR4) axis activation, reduced reactive oxygen species (ROS) production in rat glomeruli and cultured podocytes. As a result, polydatin up-regulated nephrin and podocin, down-regulated transient receptor potential cation channel 6 (TRPC6) in these animal and cell models. Moreover, the data from HIF-1α siRNA transfection showed that high fructose increased NOX4 expression and aggravated SDF-1α/CXCR4 axis activation in an HIF-1α-dependent manner, whereas polydatin down-regulated HIF-1α to inhibit NOX4 and suppressed SDF-1α/CXCR4 axis activation, ameliorating high fructose-induced podocyte oxidative stress and injury. These findings demonstrated that high fructose-driven HIF-1α/NOX4 pathway controlled podocyte oxidative stress damage. Intervention of this disturbance by polydatin could help the development of the therapeutic strategy to combat podocyte damage associated with high fructose diet.

Molecular Mechanistic Pathways Targeted by Natural Compounds in the Prevention and Treatment of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is one of the most common complications of diabetes, and its prevalence is still growing rapidly. However, the efficient therapies for this kidney disease are still limited. The pathogenesis of DKD involves glucotoxicity, lipotoxicity, inflammation, oxidative stress, and renal fibrosis. Glucotoxicity and lipotoxicity can cause oxidative stress, which can lead to inflammation and aggravate renal fibrosis. In this review, we have focused on in vitro and in vivo experiments to investigate the mechanistic pathways by which natural compounds exert their effects against the progression of DKD. The accumulated and collected data revealed that some natural compounds could regulate inflammation, oxidative stress, renal fibrosis, and activate autophagy, thereby protecting the kidney. The main pathways targeted by these reviewed compounds include the Nrf2 signaling pathway, NF-κB signaling pathway, TGF-β signaling pathway, NLRP3 inflammasome, autophagy, glycolipid metabolism and ER stress. This review presented an updated overview of the potential benefits of these natural compounds for the prevention and treatment of DKD progression, aimed to provide new potential therapeutic lead compounds and references for the innovative drug development and clinical treatment of DKD.

Recent Advances in the Emerging Therapeutic Strategies for Diabetic Kidney Diseases

Diabetic kidney disease (DKD) is one of the most common causes of end-stage renal disease worldwide. The treatment of DKD is strongly associated with clinical outcomes in patients with diabetes mellitus. Traditional therapeutic strategies focus on the control of major risk factors, such as blood glucose, blood lipids, and blood pressure. Renin–angiotensin–aldosterone system inhibitors have been the main therapeutic measures in the past, but the emergence of sodium–glucose cotransporter 2 inhibitors, incretin mimetics, and endothelin-1 receptor antagonists has provided more options for the management of DKD. Simultaneously, with advances in research on the pathogenesis of DKD, some new therapies targeting renal inflammation, fibrosis, and oxidative stress have gradually entered clinical application. In addition, some recently discovered therapeutic targets and signaling pathways, mainly in preclinical and early clinical trial stages, are expected to provide benefits for patients with DKD in the future. This review summarizes the traditional treatments and emerging management options for DKD, demonstrating recent advances in the therapeutic strategies for DKD.

Exercise Training Ameliorates Renal Oxidative Stress in Rats with Chronic Renal Failure

In patients with chronic kidney disease, exercise training with moderate intensity protects renal function and improves mortality. However, the mechanisms of the renal protective effects of exercise training in chronic kidney disease have not been clarified. This study investigated the effects of exercise training on renal NADPH oxidative and xanthine oxidase, which are major sources of reactive oxygen species, in rats with chronic renal failure. Six-week-old, male Sprague–Dawley rats were divided into the sham operation, 5/6 nephrectomy (Nx)+ sedentary, and Nx+ exercise training groups. The Nx+ exercise training group underwent treadmill running. After 12 weeks, systolic blood pressure, renal function, malondialdehyde, renal NADPH oxidase, and xanthine oxidase were examined. Nx induced hypertension, proteinuria, and renal dysfunction, and exercise training attenuated these disorders. Although the plasma levels of malondialdehyde were not different among the group, urinary levels were increased by Nx and decreased by exercise training. Renal activity and expression of NADPH oxidase and xanthine oxidase were increased by Nx and decreased by exercise training. These results indicate that exercise training attenuates hypertension and renal dysfunction and ameliorates NADPH oxidase and xanthine oxidase in rats with chronic renal failure, suggesting that the reduction of reactive oxygen species generation may be involved in the renal protective effects of exercise training.

Complanatoside A targeting NOX4 blocks renal fibrosis in diabetic mice by suppressing NLRP3 inflammasome activation and autophagy

BACKGROUND

Diabetic nephropathy (DN) is an important cause of end-stage renal disease. Complanatoside A (CA), an active component from Semen Astragali Complanati, has been reported to be a potential candidate for the treatment of kidney diseases. However, the underlying mechanisms and protective effects of CA in DN remain unclear.

PURPOSE

In this paper, the effects and the mechanism of CA against ameliorating DN were investigated in vivo and in vitro.

STUDY DESIGN

Here, a high-fat diet/streptozotocin-induced diabetic model and TGF-β1-induced HK-2 cells were used to explore the protective effects and mechanisms of CA on DN in vivo and in vitro.

METHODS

Major biochemical indexes, Histopathological morphology, and Immunohistochemistry have explored the therapeutic effect of CA on DN. Subsequently, TGF-β1-induced HK-2 cells were utilized to investigate the anti-renal fibrosis effect of CA. Finally, the mechanism of CA against renal fibrosis was studied via western blotting, immunofluorescence, transfection, and molecular docking.

RESULTS

The results showed that CA attenuated glomerular hypertrophy, collagen matrix deposition, and tubular interstitial fibrosis in diabetic mice. Moreover, the activation of TGF-β1-inducible epithelial-mesenchymal transition (EMT) was hindered by CA treatment in HK-2 cells. Mechanistically, the data suggested that upregulated NOX4 during diabetes and TGF-β1 in HK-2 cells was prominently diminished after CA treatment. Furthermore, CA exposure inhibited NLRP3 inflammasome activation and downstream inflammation gene expression such as IL-18 and IL-1β in vivo and vitro. These findings indicated that CA obstructed the EMT to protect renal tubular epithelial cells against fibrosis via blocking NLRP3 activation, which was associated with inhibiting NOX4. Besides, the markedly raised autophagy levels in the diabetic model characterized by increasing LC3II/LC3I and Beclin1 were reversed after CA treatment, which is also a pivotal mechanism against renal fibrosis. More importantly, specific NOX4 overexpressed in HK-2 cells abolished that CA exposure blocked TGF-β1-induced-EMT, ROS generation, NLRP3, and autophagy activation. Meanwhile, the inhibition of cell migration, ROS generation, autophagy, and renal inflammation after CA treatment was more pronounced in NOX4-deficient HK-2 cells.

CONCLUSION

Our findings provided evidence that CA might be a potential therapeutic agent for DN by ameliorating NLRP3 inflammasome and autophagy activation via targeting NOX4 inhibition.

Signaling pathways of chronic kidney diseases, implications for therapeutics

Chronic kidney disease (CKD) is a chronic renal dysfunction syndrome that is characterized by nephron loss, inflammation, myofibroblasts activation, and extracellular matrix (ECM) deposition. Lipotoxicity and oxidative stress are the driving force for the loss of nephron including tubules, glomerulus, and endothelium. NLRP3 inflammasome signaling, MAPK signaling, PI3K/Akt signaling, and RAAS signaling involves in lipotoxicity. The upregulated Nox expression and the decreased Nrf2 expression result in oxidative stress directly. The injured renal resident cells release proinflammatory cytokines and chemokines to recruit immune cells such as macrophages from bone marrow. NF-κB signaling, NLRP3 inflammasome signaling, JAK-STAT signaling, Toll-like receptor signaling, and cGAS-STING signaling are major signaling pathways that mediate inflammation in inflammatory cells including immune cells and injured renal resident cells. The inflammatory cells produce and secret a great number of profibrotic cytokines such as TGF-β1, Wnt ligands, and angiotensin II. TGF-β signaling, Wnt signaling, RAAS signaling, and Notch signaling evoke the activation of myofibroblasts and promote the generation of ECM. The potential therapies targeted to these signaling pathways are also introduced here. In this review, we update the key signaling pathways of lipotoxicity, oxidative stress, inflammation, and myofibroblasts activation in kidneys with chronic injury, and the targeted drugs based on the latest studies. Unifying these pathways and the targeted therapies will be instrumental to advance further basic and clinical investigation in CKD.

Nobiletin resolves left ventricular and renal changes in 2K-1C hypertensive rats

This study investigated the effects of nobiletin on cardiorenal changes and the underlying mechanisms involved in two-kidney, one-clip (2K-1C) hypertension. 2K-1C rats were treated with nobiletin (15 or 30 mg/kg/day) or losartan (10 mg/kg/day) for 4 weeks (n = 8/group). Nobiletin (30 mg/kg) reduced high levels of blood pressure and circulating angiotensin II and angiotensin-converting enzyme activity in 2K-1C rats. Left ventricular (LV) dysfunction and remodelling in 2K-1C rats were alleviated in the nobiletin-treated group (P < 0.05). Nobiletin reduced the upregulation of Ang II type I receptor (AT₁R)/JAK (Janus kinase)/STAT (signal transducer and activator of transcription) protein expression in cardiac tissue of 2K-1C rats (P < 0.05). The reduction in kidney function, and accumulation of renal fibrosis in 2K-1C rats were alleviated by nobiletin (P < 0.05). Overexpression of AT₁R and NADPH oxidase 4 (Nox4) protein in nonclipped kidney tissue was suppressed in the nobiletin-treated group (P < 0.05). The elevations in oxidative stress parameters and the reductions in antioxidant enzymes were attenuated in 2K-1C rats treated with nobiletin (P < 0.05). In summary, nobiletin had renin-angiotensin system inhibitory and antioxidant effects and attenuated LV dysfunction and remodelling via restoration of the AT₁R/JAK/STAT pathway. Nobiletin also resolved renal damage that was related to modulation of the AT₁R/Nox4 cascade in 2K-1C hypertension.

Therapeutic Implications of Ferroptosis in Renal Fibrosis

Renal fibrosis is a common feature of chronic kidney disease (CKD), and can lead to the destruction of normal renal structure and loss of kidney function. Little progress has been made in reversing fibrosis in recent years. Ferroptosis is more immunogenic than apoptosis due to the release and activation of damage-related molecular patterns (DAMPs) signals. In this paper, the relationship between renal fibrosis and ferroptosis was reviewed from the perspective of iron metabolism and lipid peroxidation, and some pharmaceuticals or chemicals associated with both ferroptosis and renal fibrosis were summarized. Other programmed cell death and ferroptosis in renal fibrosis were also firstly reviewed for comparison and further investigation.

Statins attenuate cholesterol-induced ROS via inhibiting NOX2/NOX4 and mitochondrial pathway in collecting ducts of the kidney

Background

Statins therapy has been primarily recommended for the prevention of cardiovascular risk in patients with chronic kidney diseases. Statins has also been proved some benefits in lipid-induced kidney diseases. The current study aims to investigate the protection and underlying mechanisms of statins on renal tubular injuries induced by cholesterol overloaded.

Methods

We used tubular suspensions of inner medullary collecting duct (IMCD) cells from rat kidneys and mouse collecting duct cell line mpkCCD cells to investigate the effect of statins on reactive oxygen species (ROS) production induced by cholesterol. Protein and mRNA expression of NADPH oxidase 2 (NOX2) /NOX4 was examined by Western blot and RT-PCR in vitro studies and in rats with 5/6 nephrectomy and high-fat diet. Mitochondrial morphology and membrane potential was observed by Mito-tracker and JC-1.

Results

Statins treatment was associated with decreased NOX2 and NOX4 protein expression and mRNA levels in 5/6Nx rats with high-fat diet. Statins treatment markedly reduced the ROS production in IMCD suspensions and mpkCCD cells. Also, statins reduced NOX2 and NOX4 protein expression and mRNA levels in cholesterol overload mpkCCD cells and improved mitochondrial morphology and function.

Conclusion

Statins prevented ROS production induced by cholesterol in the kidney, likely through inhibiting NOXs protein expression and improving mitochondrial function. Statins may be a therapeutic option in treating obesity-associated kidney diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02815-6.

Inhibition of the NADPH Oxidase Pathway Reduces Ferroptosis during Septic Renal Injury in Diabetic Mice

Background

Obesity and type 2 diabetes mellitus (DM) contribute to a higher mortality rate in patients with septic acute kidney injury (AKI) during sepsis. Reactive oxygen species (ROS) is the major injury factor for sepsis. This study was aimed at exploring the potential therapeutic drug for septic AKI targeting on ROS.

Methods

A murine septic AKI model was established in both wild-type and high-fat diet-fed (HFD) mice. NADPH oxidase inhibitor Vas2870 was used in vivo to explore the role of NADPH oxidase in ROS release in septic AKI in diabetic mice. Ferrostatin-1 was administered to investigate the role of ferroptosis in ROS accumulation during NADPH oxidase activating in septic AKI in diabetic mice.

Results

Compared to chow diet-fed mice, HFD diabetic mice which were subjected to LPS exhibited aggravated renal function (blood urea nitrogen, creatinine clearance, and serum cystatin C) and oxidative stress (malondialdehyde, 4-HNE, ROS, 8-OHdG, and NADPH oxidase), thus resulting in a higher mortality rate. Septic renal injury was significantly attenuated by the ferroptosis inhibitor Fer-1 in HFD-challenged mice. Furthermore, ferroptosis accumulation and related protein expression (ASCL4, FTH1, and GPX4) were altered by LPS stimulation in HFD-challenged mice and suppressed by NADPH oxidase inhibition via Vas2870 in vivo. In summary, NADPH inhibition restored septic renal function from injury by suppressing ferroptosis accumulation in HFD-challenged mice.

Conclusion

These results suggest that targeting NADPH-mediated ROS release and ferroptosis accumulation is a novel therapeutic strategy to protect the kidney from septic injury in patients with obesity and type 2 DM.

The role of reactive oxygen species derived from different NADPH oxidase isoforms and mitochondria in oxalate-induced oxidative stress and cell injury

Hyperoxaluria is a risk factor for urolithiasis and can cause renal epithelial cell injury secondary to oxidative stress. Reactive oxygen species (ROS) produced during cell damage originate from different sources and play different roles. Here, we explored the potential sources of ROS production and investigated the role of ROS from various sources in oxalate-induced oxidative stress and cell injury in normal rat kidney-52 epithelial (NRK-52E) cells. Oxalate-induced injury was assessed by lactate dehydrogenase (LDH) release experiments. 2,7-dichlorodihydrofluorescein diacetate and mitoSOX Red were used to determine the intracellular and mitochondrial ROS (mtROS) production, respectively. The expression level of Nox4, Nox2, and p22 protein was detected by Western blotting to observe the effect of oxalate on nicotinamide adenine dinucleotide phosphate oxidase (NADPH) oxidase (Nox). Furthermore, a specific NADPH oxidase subtype inhibitor and targeted mitochondrial antioxidants were used to preliminarily identify the role of ROS from different sources in renal tubular epithelial cell injury induced by oxalate. We found that oxalate inhibited cell viability, induced LDH release, and prompted intracellular and mitochondrial ROS (mtROS) production. Oxalate also decreased the protein expression level of Nox4 and increased the protein expression level of p22. Mitochondria were also a source of ROS production. In addition, Nox2 inhibitor or mtROS scavenging prevented oxalate-induced cell injury, reversed by an inhibitor of Nox4/1. We concluded that ROS from different sources might play different roles in oxalate-induced renal tubular epithelial cell injury. We also identified new potential targets for preventing or alleviating oxalate-induced renal tubular epithelial cell injury.

Graphic abstract

Oxidative Stress in Human Pathology and Aging: Molecular Mechanisms and Perspectives

Reactive oxygen and nitrogen species (RONS) are generated through various endogenous and exogenous processes; however, they are neutralized by enzymatic and non-enzymatic antioxidants. An imbalance between the generation and neutralization of oxidants results in the progression to oxidative stress (OS), which in turn gives rise to various diseases, disorders and aging. The characteristics of aging include the progressive loss of function in tissues and organs. The theory of aging explains that age-related functional losses are due to accumulation of reactive oxygen species (ROS), their subsequent damages and tissue deformities. Moreover, the diseases and disorders caused by OS include cardiovascular diseases [CVDs], chronic obstructive pulmonary disease, chronic kidney disease, neurodegenerative diseases and cancer. OS, induced by ROS, is neutralized by different enzymatic and non-enzymatic antioxidants and prevents cells, tissues and organs from damage. However, prolonged OS decreases the content of antioxidant status of cells by reducing the activities of reductants and antioxidative enzymes and gives rise to different pathological conditions. Therefore, the aim of the present review is to discuss the mechanism of ROS-induced OS signaling and their age-associated complications mediated through their toxic manifestations in order to devise effective preventive and curative natural therapeutic remedies.

Bisacurone attenuates diabetic nephropathy by ameliorating oxidative stress, inflammation and apoptosis in rats

BACKGROUND

Diabetes nephropathy (DN) is a serious diabetic problem that may progress to renal failure. The root of Curcuma longa L., often known as turmeric, provides various health benefits. Bisacurone is a bioactive terpenoid found in small amounts in turmeric that possesses anti-inflammatory and antioxidant properties. The present study focuses on the potential protective effects of bisacurone against DN via reducing renal inflammation, oxidative stress, and apoptosis.

METHODS

Type 2 diabetes was created in rats by feeding them a high-fat/high-sugar diet for 8 weeks, followed by a low dose of streptozotocin and Bisacurone (50 and 100 μg/kg bisacurone) given for 4 weeks.

RESULTS

In diabetic rats, bisacurone reduced hyperglycemia, protected against body weight (BW) loss, lowered renal markers, reduced lipid profile alterations and avoided histological abnormalities. Bisacurone treatment reduced oxidative stress by decreasing malondialdehyde (MDA) levels while enhancing antioxidant defenses through superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels. Furthermore, bisacurone treatment activated the renal Nrf2/Keap1 signaling pathway but attenuated the high levels of NFκB p65, TNF-α, IL-1β, IL-6, Cox2, and iNOS. Bisacurone also reduced Bax, caspase-3, caspase-9 and cytochrome c but increased Bcl-2 in the kidneys of diabetic rats.

CONCLUSION

In the present study, bisacurone reduces DN by reducing hyperglycemia, oxidative stress, inflammation, and apoptosis, while also increasing Nrf2/HO-1 signaling.

LncRNA MALAT1 Aggravates Renal Tubular Injury via Activating LIN28A and the Nox4/AMPK/mTOR Signaling Axis in Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy (DN) is a serious complication among patients with diabetes. Elucidating its pathogenesis is crucial for identifying novel biomarkers and therapeutic targets for DN.

METHODS

DN tissues were harvested for examining MALAT1, LIN28A and Nox4. Human kidney-2 (HK-2) cells were treated with high glucose (HG) for establishing a cell model of DN. Cell viability was examined by MTT assay. HG-induced cell apoptosis and secretion of TNF-α and IL-6 were analyzed by TUNEL and ELISA assays, respectively. RIP and RNA pull-down assays were applied to analyze the interaction between MALAT1, LIN28A and Nox4 in HK-2 and human embryonic kidney 293T (HEK-293T) cells. A rat model of DN was established to determine the role of MALAT1 in DN in vivo.

RESULTS

MALAT1, LIN28A and Nox4 were upregulated in DN tissues and HG-treated HK-2 cells. Overexpression of MALAT1, LIN28A or Nox4 reduced cell viability and enhanced cell apoptosis, ROS generation and secretion of inflammatory cytokines in HG-treated HK-2 cells, whereas knockdown of MALAT1, LIN28A or Nox4 exerted opposite effects. Furthermore, MALAT1 directly interacted with LIN28A. Moreover, MALAT1 facilitated the interaction between LIN28A and Nox4 to increase Nox4 stability. Knockdown of Nox4 relieved HG-induced injury by suppressing the AMPK/mTOR signaling in HK-2 cells. Knockdown of MALAT1 alleviated renal tubular epithelial injury by suppressing LIN28A and the Nox4/AMPK/TOR signaling in DN.

CONCLUSION

MALAT1 activates the AMPK/mTOR signaling via interacting with LIN28A to stabilize Nox4 mRNA, thereby aggravating high glucose-induced renal tubular epithelial injury. Our findings provide potential therapeutic targets for DN.

Bicalutamide Exhibits Potential to Damage Kidney via Destroying Complex I and Affecting Mitochondrial Dynamics

Bicalutamide (Bic) is an androgen deprivation therapy (ADT) for treating prostate cancer, while ADT is potentially associated with acute kidney injury. Previously, we recognized Bic induced renal mitochondria dysfunction in vitro and in vivo via the ROS -HIF1α pathway. Whether OXPHOS complex, as well as mitochondrial dynamics, can be influenced by Bic via modulation of peroxisome proliferator-activated receptor coactivator 1α (PGC1α), NADPH oxidase 4 (Nox4), mitofusins 1/2 (MFN 1/2), optic atrophy 1 (OPA1), and sirtuins (SIRTs) has not been documented. Renal mesangial cell line was treated with Bic (30~60 μM) for the indicated time. SIRTs, complex I, mitochondrial dynamics- and oxidative stress-related proteins were analyzed. Bic dose-dependently reduced mitochondrial potential, but dose- and time-dependently suppressed translocase of the outer mitochondrial membrane member 20 (Tomm 20), complex I activity. Nox4 and glutathione lead to decreased NAD⁺/NADH ratio, with upregulated superoxide dismutase 2. SIRT1 was initially stimulated and then suppressed, while SIRT3 was time- and dose-dependently downregulated. PGC1α, MFN2, and OPA1 were all upregulated, with MFN1 and pro-fission dynamin-related protein I downregulated. Bic exhibits potential to damage mitochondria via destroying complex I, complex I activity, and mitochondrial dynamics. Long-term treatment with Bic should be carefully followed up.

Jujuboside A ameliorates high fat diet and streptozotocin induced diabetic nephropathy via suppressing oxidative stress, apoptosis, and enhancing autophagy

Jujuboside A (JuA) is a triterpenoid saponins isolated from the seed of jujube (semen Ziziphi spinosae) with anti-oxidant, anti-inflammation and anti-apoptosis properties. The present study aimed to investigate the reno-protective effects of JuA on type II diabetes. JuA (20 mg/kg) and Metformin (Met, 300 mg/kg) were administrated to diabetic Sprague Dawley rat for 8 weeks daily. Our results showed that JuA reduced blood glucose and kidney function markers including 24 h urinary protein, urinary β-NAG/urinary creatinine, serum urea nitrogen, serum uric acid and serum creatinine, and relieved renal pathological changes. In addition, JuA decreased O₂^- and H₂O₂ level, enhanced SOD, CAT and GPx activities, decreased NOX4 expression and improved mitochondrial respiratory chain function through regulating respiratory chain complex expression. Moreover, JuA downregulated the expressions of mitochondrial apoptosis proteins: Bax, CytC, Apaf-1 and caspase 9. Apoptosis mediated by ER stress also been inhibited by JuA via downregulating p-PERK, p-IRE1, XBP1s, ATF4, p-CHOP and caspase 12 expressions. JuA also enhanced autophagy and mitophagy via regulating CaMKK2-AMPK-p-mTOR and PINK1/Parkin pathways. Collectively, these results indicated that JuA protected against type II diabetic nephropathy through inhibiting oxidative stress and apoptosis mediated by mitochondria and ER stress. In addition, autophagy and mitophagy was enhanced by JuA.

Mitochondrial Regulation of Diabetic Kidney Disease

The role and nature of mitochondrial dysfunction in diabetic kidney disease (DKD) has been extensively studied. Yet, the molecular drivers of mitochondrial remodeling in DKD are poorly understood. Diabetic kidney cells exhibit a cascade of mitochondrial dysfunction ranging from changes in mitochondrial morphology to significant alterations in mitochondrial biogenesis, biosynthetic, bioenergetics and production of reactive oxygen species (ROS). How these changes individually or in aggregate contribute to progression of DKD remain to be fully elucidated. Nevertheless, because of the remarkable progress in our basic understanding of the role of mitochondrial biology and its dysfunction in DKD, there is great excitement on future targeted therapies based on improving mitochondrial function in DKD. This review will highlight the latest advances in understanding the nature of mitochondria dysfunction and its role in progression of DKD, and the development of mitochondrial targets that could be potentially used to prevent its progression.

Smad3-Targeted Therapy Protects against Cisplatin-Induced AKI by Attenuating Programmed Cell Death and Inflammation via a NOX4-Dependent Mechanism

Background

Transforming growth factor-β (TGF-β)/Smad signaling is the central mediator in renal fibrosis, yet its functional role in acute kidney injury (AKI) is not fully understood. Recent evidence showed that TGF-β/Smad3 may be involved in the pathogenesis of AKI, but its functional role and mechanism of action in cisplatin-induced AKI are unclear.

Objectives

Demonstrating that Smad3 may play certain roles in cisplatin nephropathy due to its potential effect on programmed cell death and inflammation.

Methods

Here, we established a cisplatin-induced AKI mouse model with Smad3 knockout mice and created stable in vitro models with Smad3 knockdown tubular epithelial cells. In addition, we tested the potential of Smad3-targeted therapy using 2 in vivo protocols - lentivirus-mediated Smad3 silencing in vivo and use of naringenin, a monomer used in traditional Chinese medicine and a natural inhibitor of Smad3.

Results

Disruption of Smad3 attenuated cisplatin-induced kidney injury, inflammation, and NADPH oxidase 4-dependent oxidative stress. We found that Smad3-targeted therapy protected against loss of renal function and alleviated apoptosis, RIPK-mediated necroptosis, renal inflammation, and oxidative stress in cisplatin nephropathy.

Conclusions

These findings show that Smad3 promotes cisplatin-induced AKI and Smad3-targeted therapy protects against this pathological process. These findings have substantial clinical relevance, as they suggest a therapeutic target for AKI.