Renal Ischemia-reperfusion Research Articles

Removal of the catalytic subunit of DNA-protein kinase in the proximal tubules promotes DNA and tubular damage during kidney injury.

Tubular epithelial cell damage can be repaired through a series of complex signaling pathways. An early event in many forms of tubular damage is the observation of DNA damage, which can be repaired by specific pathways depending upon the type of genomic alteration.. In this study, we report that the catalytic subunit of DNA protein kinase (DNA-PKcs), a central DNA repair enzyme involved in sensing DNA damage and performing double stranded DNA break repair, plays an important role in the extent of tubular epithelial cell damage following exposure to injurious acute and chronic stimuli. Selective loss of DNA-PKcs in the proximal tubules led to increased markers of kidney dysfunction, DNA damage, and tubular epithelial cell injury in multiple models of acute kidney injury, specifically bilateral renal ischemia-reperfusion injury and single dose of cisplatin (15 mg/kg IP). In contrast, in a mouse model of kidney fibrosis and chronic kidney disease (UUO),the protective effects of DNA-PKcs was not as obvious histologically from the tissue sections. In the absence of proximal tubular DNA-PKcs, there was reduced levels of fibrotic markers, α-SMA and fibronectin, which suggests that there may be a biphasic role of DNA-PKcs depending upon the conditions exerted upon the kidney. In conclusion, this study demonstrates that the catalytic subunit of DNA-PKcs plays a context-dependent role in the kidney to reduce DNA damage during exposure to various types of acute, but not chronic forms of injurious stimuli.

Remote liver ischemic preconditioning protects against renal ischemia/reperfusion injury via phosphorylation of extracellular signal-regulated kinases 1 and 2 in mice.

Perioperative acute kidney injury (AKI), which is mainly mediated by renal ischemia‒reperfusion (I/R) injury, is commonly observed in clinical practice. However, effective measures for preventing and treating this perioperative complication are still lacking in the clinic. Thus, we designed this study to examine whether remote liver ischemic preconditioning (RLIPC) has a protective effect on damage caused by renal I/R injury. In a rodent model, 30 mice were divided into five groups to assess the effects of RLIPC and ERK1/2 inhibition on AKI. The groups included the sham-operated (sham), kidney ischemia and reperfusion (CON), remote liver ischemic preconditioning (RLIPC), CON with the ERK1/2 inhibitor U0126 (CON+U0126), and RLIPC with U0126 (RLIPC+U0126). RLIPC consisted of 4 liver ischemia cycles before renal ischemia. Renal function and injury were assessed through biochemical assays, histology, cell apoptosis and protein phosphorylation analysis. RLIPC significantly mitigated renal dysfunction, tissue damage, inflammation, and apoptosis caused by I/R, which was associated with ERK1/2 phosphorylation. Furthermore, ERK1/2 inhibition with U0126 negated the protective effects of RLIPC and exacerbated renal injury. To summarize, we demonstrated that RLIPC has a strong renoprotective effect on kidneys post I/R injury and that this effect may be mediated by phosphorylation of ERK1/2.

Exploring the therapeutic potential of Modafinil in mitigating renal ischemia-reperfusion injury in rats.

Renal ischemia reperfusion injury (IRI) is a post-ischemic event, which can lead to subsequent acute kidney injury (AKI), transplant failure, renal dysfunction and fibrosis via heightened oxidative stress and production of inflammatory cytokines and chemokines. This study aims to assess the effect of Modafinil, a wake-promoting agent with previously proven anti-inflammatory and anti-oxidative properties, on ameliorating renal IRI. A total of 30 male Wistar rats were divided into five groups: Sham-operated group, ischemia reperfusion (I/R) control group and Modafinil pre-treated groups (at different doses of 50, 100 and 150 mg/kg). IRI was induced by means of bilaterally clamping the renal arteries for 45 min, followed by 24 h of reperfusion. Tissue pathological assessments demonstrated a reduction of glomerular, vascular and interstitial injury at doses of 50 and 100 mg/kg of Modafinil. The biochemical studies showed a significant decrease in tissue pro-inflammatory factors, including tumor necrosis factor alpha (TNF-α), Interleukin-18 (IL-18) and lactate dehydrogenase (LDH). Moreover, an elevation was observed in levels of super oxide dismutase (SOD) and catalase, indicating the reduction of oxidative stress. Furthermore, the levels of creatinine (Cr), urea and neutrophil gelatinase-associated lipocalin (NGAL) were declined, indicating the improvement in renal function at effective doses of Modafinil (50 and 100 mg/kg) compared to the I/R control group without Modafinil pre-treatment. Our findings suggest that Modafinil holds promise as an effective therapeutic agent to address the clinical challenges associated with kidney IRI reducing the need for hospitalization and potentially alleviating related morbidities.

Extracellular Vesicle Transplantation Is Beneficial for Acute Kidney Injury.

Under vasculogenic conditioning, certain pro-inflammatory subsets within peripheral blood mononuclear cells (PBMCs) undergo phenotypic transformation into pro-regenerative types, such as vasculogenic endothelial progenitor cells, M2 macrophages, and regulatory T cells. These transformed cells are collectively termed regeneration-associated cells (RACs). In this study, we aimed to investigate the therapeutic efficacy of RAC-derived extracellular vesicles (RACev) compared with a vehicle-treated group in the context of renal ischemia-reperfusion injury (R-IRI). Human PBMCs were cultured with defined growth factor cocktails for seven days to harvest RACs. EV quantity and size were characterized by nanoparticle tracking analysis. Notably, the systemic injection of RACev significantly decreased serum creatinine and blood urine nitrogen at day three compared to the control group. Histologically, the treatment group showed less fibrosis in the cortex and medullary areas (p < 0.04 and p < 0.01) compared to the control group. The CD31 staining confirmed enhanced capillary densities in the treatment group compared to the control group (p < 0.003). These beneficial effects were accompanied by angiogenesis, anti-fibrosis, anti-inflammation, and anti-apoptosis RACev miR delivery to ischemic injury to control inflammatory, endothelial mesenchymal transition, and hypoxia pathways. In vivo bioluminescence analysis demonstrated a preferential accumulation of RACev in the IR-injured kidney. The systemic transplantation of RACev beneficially restored kidney function by protecting from tissue fibrosis and through anti-inflammation, angiogenesis, and anti-apoptosis miR delivery to the ischemic tissue.

Crizotinib and its enantiomer suppress ferroptosis by decreasing PE-O-PUFA content

Ferroptosis is a specific form of cell death characterized by excessive accumulation of cellular lipid peroxides. Ferroptosis is closely associated with various diseases, inhibition of which may help alleviate multi-organ injury caused by ischemia-reperfusion and enhance the anti-tumor effect by promoting the immunity of T cells. However, clinical approved drugs targeting ferroptosis process remain rare. In this study, we unexpectedly found that (R)-crizotinib, the first-generation ALK inhibitor, has potent inhibitory activity against ferroptosis across various cell lines. Moreover, its chiral molecule (S)-crizotinib, which was considered to share no common targets with (R)-crizotinib, also suppresses ferroptosis with an efficacy similar to that of (R)-crizotinib. We further demonstrated that both crizotinib enantiomers inhibit ferroptosis independently of their known targets, but through a common mechanism involving the targeting of AGPAT3-mediated synthesis of ether-linked polyunsaturated fatty acids (PE-O-PUFA), which are known to promote lipid-ROS generation and ferroptosis. In line with their activity in cell lines, (R)-crizotinib and (S)-crizotinib effectively mitigate renal ischemia-reperfusion injury in mice. Furthermore, the two compounds also inhibit lipid-ROS accumulation in CD8+ T cells in draining lymph nodes of B16-F10 subcutaneous xenograft mice, thereby promoting anti-tumor effects. Collectively, our study firstly reports a common activity shared by (R)-crizotinib and (S)-crizotinib in ferroptosis regulation. As a clinically approved drug, (R)-crizotinib has well-established pharmacokinetics and safety, which makes it a promising candidate for repurposing. Given the current lack of FDA-approved ferroptosis inhibitors, our findings suggest therapeutically repurposing (R)-crizotinib as well as its enantiomer (S)-crizotinib for treating ferroptosis-related diseases.

Mesoporous zinc-polyphenol nanozyme for attenuating renal ischemia-reperfusion injury.

Aim: To target the reactive oxygen species (ROS) accumulation and renal tubular epithelial cell (rTEC) death in renal ischemia-reperfusion injury (IRI), we constructed a nanoparticle that offers ROS scavenging and rTEC-death inhibition: mesoporous zinc-tannic acid nanozyme (ZnTA).Materials & methods: After successfully constructing ZnTA, we proceeded to examine its effect on ROS accumulation, cellular ferroptosisand apoptosis, as well as injury severity.Results: Malondialdehyde, Fe2+ amounts and 4-HNE staining demonstrated that ZnTA effectively attenuated rTEC ferroptosis. TUNEL staining confirmed that Zn2+ carried by ZnTA could effectively inhibit caspase 3 and caspase 9, mitigating apoptosis. Finally, it reduced renal IRI through the synergistic effect of ROSscavenging and cell-death inhibition.Conclusion: This study is expected to provide a paradigm for a combined therapeutic strategy for renal IRI.

Perinatal asphyxia leads to acute kidney damage and increased renal susceptibility in adulthood.

Perinatal asphyxia (PA) poses a significant threat to multiple organs, particularly the kidneys. Diagnosing PA-associated kidney injury remains challenging, and treatment options are inadequate. Furthermore, there is a lack of long-term follow-up data regarding the renal implications of PA. In this study, 7-day-old male Wistar rats were exposed to PA using a gas mixture (4% O2; 20% CO2 in N2 for 15 min) to investigate molecular pathways linked to renal tubular damage, hypoxia, angiogenesis, heat shock response, inflammation, and fibrosis in the kidney. In a second experiment, adult rats with a history of PA were subjected to moderate renal ischemia-reperfusion (IR) injury to test the hypothesis that PA exacerbates renal susceptibility. Our results revealed an increased gene expression of renal injury markers (kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin), hypoxic and heat shock factors (hypoxia-inducible factor-1α, heat shock factor-1, and heat shock protein-27), proinflammatory cytokines (interleukin-1β, interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1), and fibrotic markers (transforming growth factor-β, connective tissue growth factor, and fibronectin) promptly after PA. Moreover, a machine learning model was identified through random forest analysis, demonstrating an impressive classification accuracy (95.5%) for PA. Post-PA rats showed exacerbated functional decline and tubular injury and more intense hypoxic, heat shock, proinflammatory, and profibrotic response after renal IR injury compared with controls. In conclusion, PA leads to subclinical kidney injury, which may increase the susceptibility to subsequent renal damage later in life. In addition, the parameters identified through random forest analysis provide a robust foundation for future biomarker research in the context of PA.NEW & NOTEWORTHY This article demonstrates that perinatal asphyxia leads to subclinical kidney injury that permanently increases renal susceptibility to subsequent ischemic injury. We identified major molecular pathways involved in perinatal asphyxia-induced renal complications, highlighting potential targets of therapeutic approaches. In addition, random forest analysis revealed a model that classifies perinatal asphyxia with 95.5% accuracy that may provide a strong foundation for further biomarker research. These findings underscore the importance of multiorgan follow-up for perinatal asphyxia-affected patients.

SENP1 reduces oxidative stress and apoptosis in renal ischaemia-reperfusion injury by deSUMOylation of HIF-1α.

Renal ischaemia-reperfusion injury (RIRI) is a primary cause of acute kidney damage, occurring frequently insituations like renal transplantation, yet the underlying mechanisms were not fully understood. Sentrin-specific protease 1 (SENP1) is an important member of the SENP family, which is widely involved in various diseases. However, the role of SENP1 in RIRI has been unclear. In our study, we discovered that SENP1 was involved in RIRI and reduced renal cell apoptosis and oxidative stress at elevated levels. Further mechanistic studies showed that hypoxia-inducible factor-1α (HIF-1α) was identified as a substrate of SENP1. Furthermore, SENP1 deSUMOylated HIF-1α, which reduced the degradation of HIF-1α, and exerted a renoprotective function. In addition, the protective function was lost after application of the HIF-1α specific inhibitor KC7F2. Briefly, our results fully demonstrated that SENP1 reduced the degradation of HIF-1α and attenuated oxidative stress and apoptosis in RIRI by regulating the deSUMOylation of HIF-1α, suggesting that SENP1 may serve as a potential therapeutic target for the treatment of RIRI.

Ezetimibe ketone protects against renal ischemia-reperfusion injury and attenuates oxidative stress via activation of the Nrf2/HO-1 signaling pathway.

Recently, ezetimibe (EZM) has been suggested to be a potent Nrf2 activator that is important for preventing oxidative stress. Interestingly, we found that its metabolite ezetimibe ketone (EZM-K) also has antioxidant effects. Thus, we investigated the role of EZM-K in preventing renal ischemia‒reperfusion injury (RIRI). Cultured NRK-52E cells were subjected to simulated IR with or without EZM-K. Rats were used to simulate in vivo experiments. EZM-K alleviated H2O2-induced apoptosis and reactive oxygen species (ROS) and upregulated Nrf2 and HO-1 levels in NRK-52E cells. A HO-1 and a Nrf2 inhibitor reversed the protective effects of EZM-K. In the rat RIRI model, pretreatment with EZM-K activated the Nrf2/HO-1 signaling pathway, suppressed tubular injury and inflammation, and improved renal function. EZM-K significantly prevented renal injury caused by ischemia‒reperfusion via the Nrf2/HO-1 signaling axis both in vivo and in vitro. The other metabolite of EZM, ezetimibe glucuronide (EZM-G) had no protective effects against ROS in RIRI. EZM-G also had no antioxidant effects and could not activate Nrf2/HO-1 signal pathway. Our findings also indicated the therapeutic potential of EZM-K in preventing RIRI.

Can Apigenin Be an Effective Therapeutic Agent Against Experimental Renal Ischemia-Reperfusion Injury?

Aim: This study aims to reveal the effects of two doses of apigenin (API) against renal ischemia-reperfusion injury (R I/R). Material and Methods: For this purpose, 5 and 10 mg/kg doses of API were preferred in our study, and the groups were designed as sham, R I/R, 5 mg/kg API, and 10 mg/kg API groups for the implementation of the experimental protocol. In the R I/R model, 1-hour ischemia and 24-hour reperfusion periods were preferred. Oxidative and inflammatory markers were measured biochemically in samples taken at the end of the experiment. Results: Biochemical results showed that oxidative and inflammatory markers increased significantly in the R I/R group, but antioxidant activities decreased significantly. In the 5 and 10 mg/kg API groups, R I/R damage was alleviated considerably, with these markers approaching the sham group values. Conclusion: As a result, the study's results determined that two different doses of API were effective against R I/R-induced kidney damage.

Hypoxia-preconditioned WJ-MSC spheroid-derived exosomes delivering miR-210 for renal cell restoration in hypoxia-reoxygenation injury

BackgroundRecent advancements in mesenchymal stem cell (MSC) technology have paved the way for innovative treatment options for various diseases. These stem cells play a crucial role in tissue regeneration and repair, releasing local anti-inflammatory and healing signals. However, challenges such as homing issues and tumorigenicity have led to exploring MSC-exosomes as a promising alternative. MSC-exosomes have shown therapeutic potential in conditions like renal ischemia-reperfusion injury, but low production yields hinder their clinical use.MethodsTo address this limitation, we examined hypoxic preconditioning of Wharton jelly-derived MSCs (WJ-MSCs) 3D-cultured in spheroids on isolated exosome yields and miR-21 expression. We then evaluated their capacity to load miR-210 into HEK-293 cells and mitigate ROS production, consequently enhancing their survival and migration under hypoxia-reoxygenation conditions.ResultsMiR-210 overexpression was significantly induced by optimized culture and preconditioning conditions, which also improved the production yield of exosomes from grown MSCs. The exosomes enriched with miR-210 demonstrated a protective effect by improving survival, reducing apoptosis and ROS accumulation in damaged renal cells, and ultimately promoting cell migration.ConclusionThe present study underscores the possibility of employing advanced techniques to maximize the therapeutic attributes of exosomes produced from WJ-MSC spheroid for improved recovery outcomes in ischemia-reperfusion injuries.

Hydrogen sulphide reduces renal ischemia-reperfusion injury by enhancing autophagy and reducing oxidative stress.

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury. Hydrogen sulphide (H2S) exerts a protective effect in renal IRI. The present study was carried out to investigate the effects of exogenous H2S on renal IRI by regulating autophagy in mice. Mice were randomly assigned to control, IRI and NaHS (an H2S donor, 28, 56 and 100 μmol/kg) groups. Renal IRI was induced by clamping the bilateral renal pedicles with non-traumatic arterial clamp for 45 min and then reperfused for 24 h. Mice were administered intraperitoneally with NaHS 20 min prior to renal ischemia. Sham group mice underwent the same procedures without clamping. Serum and kidney tissues were harvested 24 h after reperfusion for functional, histological, oxidative stress, and autophagic determination. Compared with the control group, the concentrations of serum creatinine (Scr), blood urea nitrogen (BUN), and malondialdehyde (MDA), the protein levels of LC3II/I, Beclin-1 and P62, as well as the number of autophagosomes were significantly increased, but the activity of superoxide dismutase (SOD) was decreased after renal IRI. NaHS pre-treatment dramatically attenuated renal IRI-induced renal dysfunction, histological changes, MDA concentration and p62 expression in a dose-dependent manner. However, NaHS increased the SOD activity and the protein levels of LC3II/I and Beclin-1. These results indicate that exogenous H2S protects the kidney from IRI through enhancement of autophagy and reduction of oxidative stress. Novel H2S donors could be developed in the treatment of renal IRI.

ISL1-overexpressing BMSCs attenuate renal ischemia-reperfusion injury by suppressing apoptosis and oxidative stress through the paracrine action

Ischemia-reperfusion injury (IRI) is a major event in renal transplantation, leading to adverse outcomes. Bone marrow mesenchymal stem cells (BMSCs) are novel promising therapeutics for repairing kidney injuries. The therapeutic efficacy of BMSCs with ISL1 overexpression in renal IRI and its underlying mechanism need to be investigated. The unilateral renal IRI rat model was established to mimic clinical acute kidney injury. Rats were injected with PBS, BMSCs-Scrambled or BMSCs-ISL1 via the tail vein at the timepoint of reperfusion, and then sacrificed after 24 h of reperfusion. The administration of BMSCs-ISL1 significantly improved renal function, inhibited tubular cells apoptosis, inflammation, oxidative stress in rats. In vitro, HKC cells subjected to H2O2 stimulation were pretreated with the conditioned medium (CM) of BMSCs-Scrambled or BMSCs-ISL1. The pretreatment of ISL1-CM attenuated apoptosis and oxidative stress induced by H2O2 in HKC cells. Our proteomic data suggested that haptoglobin (Hp) was one of the secretory proteins in ISL1-CM. Subsequent experiments confirmed that Hp was the important paracrine factor from BMSCs-ISL1 that exerted anti-apoptotic and antioxidant functions. Mechanistically, Hp played a cytoprotective role via the inhibition of ERK signaling pathway, which could be abrogated by Ro 67-7476, the ERK phosphorylation agonist. The results suggested that paracrine action may be the main mechanism for BMSCs-ISL1 to exert protective effects. As an important anti-apoptotic and antioxidant factor in ISL1-CM, Hp may serve as a new therapeutic agent for treating IRI, providing new insights for overcoming the long-term adverse effects of stem cell therapy.

Multi-parametric MRI-based machine learning model for prediction of pathological grade of renal injury in a rat kidney cold ischemia-reperfusion injury model

BackgroundRenal cold ischemia-reperfusion injury (CIRI), a pathological process during kidney transplantation, may result in delayed graft function and negatively impact graft survival and function. There is a lack of an accurate and non-invasive tool for evaluating the degree of CIRI. Multi-parametric MRI has been widely used to detect and evaluate kidney injury. The machine learning algorithms introduced the opportunity to combine biomarkers from different MRI metrics into a single classifier.ObjectiveTo evaluate the performance of multi-parametric magnetic resonance imaging for grading renal injury in a rat model of renal cold ischemia-reperfusion injury using a machine learning approach.MethodsEighty male SD rats were selected to establish a renal cold ischemia -reperfusion model, and all performed multiparametric MRI scans (DWI, IVIM, DKI, BOLD, T1mapping and ASL), followed by pathological analysis. A total of 25 parameters of renal cortex and medulla were analyzed as features. The pathology scores were divided into 3 groups using K-means clustering method. Lasso regression was applied for the initial selecting of features. The optimal features and the best techniques for pathological grading were obtained. Multiple classifiers were used to construct models to evaluate the predictive value for pathology grading.ResultsAll rats were categorized into mild, moderate, and severe injury group according the pathologic scores. The 8 features that correlated better with the pathologic classification were medullary and cortical Dp, cortical T2*, cortical Fp, medullary T2*, ∆T1, cortical RBF, medullary T1. The accuracy(0.83, 0.850, 0.81, respectively) and AUC (0.95, 0.93, 0.90, respectively) for pathologic classification of the logistic regression, SVM, and RF are significantly higher than other classifiers. For the logistic model and combining logistic, RF and SVM model of different techniques for pathology grading, the stable and perform are both well. Based on logistic regression, IVIM has the highest AUC (0.93) for pathological grading, followed by BOLD(0.90).ConclusionThe multi-parametric MRI-based machine learning model could be valuable for noninvasive assessment of the degree of renal injury.

Rational design of an activatable dual-color fluorogenic probe for revealing the interaction of adenosine-5′-triphosphate and peroxynitrite in pyroptosis associated with acute kidney injury

ATP and ONOO- play unique roles in various biological events and exhibit notable interactions. To date, there is no available chemical tool for investigating the correlation between ATP and ONOO- concentrations in pyroptosis associated with acute kidney injury (AKI). Herein, we designed a novel dual-color near-infrared fluorescent (NIRF) probe P2 for simultaneous visualization of ATP and ONOO- both in vitro and in vivo. Unlike previously reported single-site fluorescent probes, P2 enabled concurrent imaging of ATP and ONOO- in two distinct fluorescence channels, with emission wavelengths centered at 585 and 690 nm, which greatly reduced spectral cross-talk. Employing a HK-2 pyroptosis model, a significant interaction between ATP and ONOO- was unveiled. Elevated ONOO- production was found to correlate with decreased ATP levels; conversely, an increase in ATP levels was associated with rapid ONOO- scavenging. Remarkably, P2 allowed the assessment of cellular hypoxia by monitoring ATP and ONOO- concentrations. The commercial ONOO--scavenger uric acid showcased a protective effect on HK-2 cells via inhibition of the cellular pyroptosis pathway. Furthermore, P2 was successfully employed for imaging of ATP and ONOO- in the AKI mice model. Our findings confirmed that renal ischemia-reperfusion triggered a rise in ONOO- levels, concurrent with a decline in ATP levels. Surprisingly, the cells exhibited a compensatory recovery of ATP levels as the reperfusion time was prolonged. These results suggested the newly devised P2, as a pivotal chemical tool for the simultaneous monitoring of ATP and ONOO-, might open new avenues for disease diagnosis and treatment.

A cloud-based learning module for biomarker discovery.

This manuscript describes the development of a resource module that is part of a learning platform named "NIGMS Sandbox for Cloud-based Learning" https://github.com/NIGMS/NIGMS-Sandbox. The overall genesis of the Sandbox is described in the editorial NIGMS Sandbox at the beginning of this Supplement. This module delivers learning materials on basic principles in biomarker discovery in an interactive format that uses appropriate cloud resources for data access and analyses. In collaboration with Google Cloud, Deloitte Consulting and NIGMS, the Rhode Island INBRE Molecular Informatics Core developed a cloud-based training module for biomarker discovery. The module consists of nine submodules covering various topics on biomarker discovery and assessment and is deployed on the Google Cloud Platform and available for public use through the NIGMS Sandbox. The submodules are written as a series of Jupyter Notebooks utilizing R and Bioconductor for biomarker and omics data analysis. The submodules cover the following topics: 1) introduction to biomarkers; 2) introduction to R data structures; 3) introduction to linear models; 4) introduction to exploratory analysis; 5) rat renal ischemia-reperfusion injury case study; (6) linear and logistic regression for comparison of quantitative biomarkers; 7) exploratory analysis of proteomics IRI data; 8) identification of IRI biomarkers from proteomic data; and 9) machine learning methods for biomarker discovery. Each notebook includes an in-line quiz for self-assessment on the submodule topic and an overview video is available on YouTube (https://www.youtube.com/watch?v=2-Q9Ax8EW84). This manuscript describes the development of a resource module that is part of a learning platform named ``NIGMS Sandbox for Cloud-based Learning'' https://github.com/NIGMS/NIGMS-Sandbox. The overall genesis of the Sandbox is described in the editorial NIGMS Sandbox [1] at the beginning of this Supplement. This module delivers learning materials on the analysis of bulk and single-cell ATAC-seq data in an interactive format that uses appropriate cloud resources for data access and analyses.

EValuating the Effect of periopeRaTIve empaGliflOzin on cardiac surgery associated acute kidney injury: rationale and design of the VERTIGO study.

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a serious complication in patients undergoing cardiac surgery with extracorporeal circulation (ECC) that increases postoperative complications and mortality. CSA-AKI develops due to a combination of patient- and surgery-related risk factors that enhance renal ischemia-reperfusion injury. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) such as empagliflozin reduce renal glucose reabsorption, improving tubulo-glomerular feedback, reducing inflammation and decreasing intraglomerular pressure. Preclinical studies have observed that SGLT2i may provide significant protection against renal ischemia-reperfusion injury due to their effects on inadequate mitochondrial function, reactive oxygen species activity or renal peritubular capillary congestion, all hallmarks of CSA-AKI. The VERTIGO (EValuating the Effect of periopeRaTIve empaGliflOzin) trial is a Phase 3, investigator-initiated, randomized, double-blind, placebo-controlled, multicenter study that aims to explore whether empagliflozin can reduce the incidence of adverse renal outcomes in cardiac surgery patients. The VERTIGO study (EudraCT: 2021-004938-11) will enroll 608 patients that require elective cardiac surgery with ECC. Patients will be randomly assigned in a 1:1 ratio to receive either empagliflozin 10mg orally daily or placebo. Study treatment will start 5days before surgery and will continue during the first 7days postoperatively. All participants will receive standard care according to local practice guidelines. The primary endpoint of the study will be the proportion of patients that develop major adverse kidney events during the first 90days after surgery, defined as ≥25% renal function decline, renal replacement therapy initiation or death. Secondary, tertiary and safety endpoints will include rates of AKI during index hospitalization, postoperative complications and observed adverse events. The VERTIGO trial will describe the efficacy and safety of empagliflozin in preventing CSA-AKI. Patient recruitment is expected to start in May 2024.

High STING expression exacerbates renal ischemia-reperfusion injury in mice by regulating the TLR4/NF-κB/NLRP3 pathway and promoting inflammation and apoptosis

To investigate renal expression level of STING in mice with renal ischemia-reperfusion injury (IRI) and its regulatory role in IRI. C57BL/6 mice were divided into sham operation group, IRI (induced by clamping the renal artery) model group, IRI+DMSO treatment group, and IRI+SN-011 treatment group. Serum creatinine and blood urea nitrogen of the mice were analyzed, and pathological changes in the renal tissue were assessed with PAS staining. RT-qPCR, ELISA, Western blotting, and immunohistochemistry were used to detect the expression levels of STING, KIM-1, Bcl-2, Bax, caspase-3, TLR4, P65, NLRP3, caspase-1, CD68, MPO, IL-1β, IL-6, and TNF-α in the renal tissues. In the cell experiment, HK-2 cells exposed to hypoxia-reoxygenation (H/R) were treated with DMSO or SN-011, and cellular STING expression levels and cell apoptosis were analyzed using RT-qPCR, Western blotting or flow cytometry. In C57BL/6 mice, renal IRI induced obvious renal tissue damage, elevation of serum creatinine and blood urea nitrogen levels and renal expression levels of KIM-1, STING, TLR4, P65, NLRP3, caspase-1, caspase-3, Bax, CD68, MPO, IL-1β, IL-6, and TNF-α, and reduction of Bcl-2 expression level. Treatment of the mouse models with SN-011 for inhibiting STING expression significantly alleviated these changes. In HK-2 cells, H/R exposure caused significant elevation of cellular STING expression and obviously increased cell apoptosis rate, which was significantly lowered by treatment with SN-011. Renal STING expression is elevated in mice with renal IRI to exacerbate renal injury by regulating the TLR4/NF-κB/NLRP3 pathway and promoting inflammation and apoptosis in the renal tissues.

DNA Origami Enhanced Cytokine Immunotherapy for Alleviating Renal Ischemia-Reperfusion Injury.

Renal ischemia-reperfusion injury (IRI) is a major contributing factor to the development of acute kidney injury (AKI) and has resulted in considerable morbidity and mortality. Persistent inflammatory responses and excessive reactive oxygen species (ROS) in the kidney following IRI can severely delay tissue repair, making it challenging to effectively promote IRI regeneration. Herein, we report an approach to enhance immunotherapy using interleukin-10 (IL-10) to promote IRI regeneration by loading IL-10 onto rectangular DNA origami nanostructures (rDON). rDON can significantly enhance the renal accumulation and retention time of IL-10, enabling it to effectively polarize type 1 macrophages into type 2 macrophages, thereby significantly reducing proinflammatory factors and increasing anti-inflammatory factors. In addition, DNA origami helps mitigate the harmful effects of ROS during renal IRI. The administration of IL-10-loaded DNA origami effectively improves kidney function, resulting in a notable reduction in blood urea nitrogen, serum uric acid, and serum creatinine levels. Our study demonstrates that the integration of anti-inflammatory cytokines within DNA origami holds promise as a strategic approach for cytokine immunotherapy in patients with AKI and other renal disorders.

Renal ischemia/reperfusion induces prominent progressive kidney disease in diabetic mice.

Acute kidney injury (AKI) is a public health concern associated with high rates of mortality, even in milder cases. One of the reasons for the difficulty in managing AKI in patients is due to its association with pre-existing comorbidities, such as diabetes. In fact, diabetes increases the susceptibility to develop more severe AKI after renal ischemia. However, the long-term effects of this association are not known. Thus, an experimental model was designed to evaluate the chronic effects of renal ischemia/reperfusion (IR) in streptozotocin (STZ)-treated mice. We focused on the glomerular and tubulointerstitial damage, as well as kidney function and metabolic profile. It was found that pre-existing diabetes may potentiate progressive kidney disease after AKI, mainly by exacerbating proinflammatory and sustaining fibrotic responses and altering renal glucose metabolism. To our knowledge, this is the first report that highlights the long-term effects of renal IR on diabetes. The findings of this study can support the management of AKI in clinical practice.NEW & NOTEWORTHY This study demonstrated that early diabetes potentiates progressive kidney disease after ischemia/reperfusion (IR)-induced acute kidney injury, mainly by exacerbating pro-inflammatory and sustaining fibrotic responses and altering renal glucose metabolism. Thus, these findings will contribute to the therapeutic support of patients with type 1 diabetes with eventual renal IR intervention in clinical practice.