Renal Ischemia-reperfusion Injury Research Articles

Potential nephroprotective effect of dapagliflozin against renal ischemia reperfusion injury in rats via activation of autophagy pathway and inhibition of inflammation, oxidative stress and apoptosis

Renal ischemia/reperfusion injury is a common cause of acute kidney injury (AKI), causing tissue damage, inflammation and oxidative stress. Autophagy, responsible for breakdown and recycling of cytoplasmic components. In hypoxic and ischemic renal damage, autophagy may serve as a survival strategy for the cells. Dapagliflozin has been shown to have protective effects against ischemia. Objective: The study investigates the potential nephro-protective effects of dapagliflozin on renal ischemia reperfusion injury, evaluating its antioxidant, anti-inflammatory, anti-apoptotic effects and activation of autophagy via biochemical parameters and histopathological changes in adult male rats. Material and method: In this study, twenty eight male rats weighing between 200-300g, were divided into 4 groups sham, RIRI, DMSO, Dapagliflozin pretreated groups. All groups subjected to 30 min. of ischemia then 24 h of reperfusion except sham undergo the same anesthesia and surgical procedures except for bilateral renal ischemia. Dapagliflozin 1mg/kg and DMSO was given 2 hours before the induction of ischemia. Results: The study found that blood urea and serum creatinine levels increased in RIRI and DMSO groups when compared with sham group. Renal tissue levels of IL-6, Kim-1, caspase-3, LC-3 and Akt were also elevated in RIRI while GSH levels decreased in the RIRI. Dapagliflozin group showed significant increases in GSH, LC-3 and Akt levels when compared to sham group. Dapagliflozin reduced serum urea and creatinine levels, and renal tissue levels of IL-6, Kim-1, and caspase-3 also reduced. Conclusion: Dapagliflozin significantly reduced renal damage in rat model due to its antioxidant, anti-inflammatory, anti-apoptotic, and activation autophagy.

Research progress on the pathogenesis of AKI complicated by ECMO.

Extracorporeal membrane oxygenation (ECMO) stands as a pivotal intervention for patients grappling with cardiopulmonary insufficiency. However, alongside its therapeutic benefits, ECMO carries the risk of complications, with acute kidney injury (AKI) emerging as a significant concern. The precise pathophysiological underpinnings of AKI in the context of ECMO remain incompletely elucidated. A comprehensive literature review was conducted to explore the epidemiology and pathophysiological mechanisms underlying the utilization of ECMO in the management of AKI. ECMO initiates a multifaceted cascade of inflammatory reactions, encompassing complement activation, endothelial dysfunction, white blood cell activation, and cytokine release. Furthermore, factors such as renal hypoperfusion, ischemia-reperfusion injury, hemolysis, and fluid overload exacerbate AKI. Specifically, veno-arterial ECMO (VA-ECMO) may directly induce renal hypoperfusion, whereas veno-venous ECMO (VV-ECMO) predominantly impacts pulmonary function, indirectly influencing renal function. While ECMO offers significant therapeutic advantages, AKI persists as a potentially fatal complication. A thorough comprehension of the pathogenesis underlying ECMO-associated AKI is imperative for effective prevention and management strategies. Moreover, additional research is warranted to delineate the incidence of AKI secondary to ECMO and to refine clinical approaches accordingly.

Liraglutide alleviates ferroptosis in renal ischemia reperfusion injury via inhibiting macrophage extracellular trap formation

Background and purposeRenal transplantation and other conditions with transiently reduced blood flow is major cause of renal ischemia/reperfusion injury (RIRI), a therapeutic challenge clinically. This study investigated the role of liraglutide in ferroptosis-associated RIRI via macrophage extracellular traps (METs). MethodsAnimal model with RIRI was established in C57BL/6J mice. A total of 72 C57BL/6J mice were used with 8 mice per group. Primary tubular epithelium was co-culture with RAW264.7 under hypoxia/reoxygenation (H/R) condition to mimic in vitro. Liraglutide was administrated into mice and cells. Extracellular DNA, neutrophil elastase and myeloperoxidase in serum and supernatant of cell medium were collected for measuring METs. F4/80 and citH3 were labeled to show METs. ResultsLiraglutide relieved RIRI and ferroptosis in vivo, and inhibited renal I/R-induced METs both in vivo and in vitro. F4/80 and citrullinated histone H3 (citH3) were highly co-localized after RIRI. Liraglutide attenuated the co-localization of citH3 and F4/80. Expressions of M2 markers were enhanced whereas these of M1 markers suppressed during liraglutide treatment in RIRI. Phosphorylation of signal transducer and activator of transcription (STAT)1, 3 and 6 were increased in RIRI mice and H/R-induced RAW264.7. However, liraglutide decreased phosphorylation of STAT1 and increased phosphorylation of STAT3 and STAT6. STAT3/6 inhibition reversed liraglutide-inhibited M1 polarization, extracellular traps and ferroptosis. ConclusionLiraglutide inhibited ferroptosis-induced renal dysfunction since it skewed macrophage polarization into M2 phenotype that interfered the formation of extracellular traps based on STAT3/6 pathway during RIRI. Liraglutide was proposed to be used for RIRI clinical treatment.

Silibinin attenuates ferroptosis in acute kidney injury by targeting FTH1

Acute kidney injury (AKI) is primarily caused by renal ischemia-reperfusion injury (IRI), which is one of the most prevalent triggers. Currently, preventive and therapeutic measures remain limited. Ferroptosis plays a significant role in the pathophysiological process of IRI-induced AKI and is considered a key target for improving its outcomes. Silibinin, a polyphenolic flavonoid, possesses diverse pharmacological properties and is widely used as an effective therapeutic agent for liver diseases. Recent studies have reported that silibinin may improves kidney diseases, though the underlying mechanism remain unclear. In this study, we investigated whether silibinin protects against IRI-induced AKI and explored its mechanism of action. Our findings indicated that pretreatment with silibinin alleviated renal dysfunction, pathological damage, and inflammation in IRI-AKI mice. Furthermore, the results demonstrated that silibinin inhibited ferroptosis both in vivo and in vitro. Proteome microarrays were used to identify silibinin's target, and our results revealed that silibinin binds to FTH1. This binding affinity was confirmed through molecular docking, SPRi, CETSA, and DARTS. Additionally, co-IP assays demonstrated that silibinin disrupted the NCOA4-FTH1 interaction, inhibiting ferritinophagy. Finally, the inhibitory effects of silibinin on ferroptosis were reversed by knocking down FTH1 in vitro. In conclusion, our study shows that silibinin effectively alleviates AKI by targeting FTH1 to reduce ferroptosis, suggesting that silibinin could be developed as a potential therapeutic agent for managing and treating AKI.

Mitophagy Regulates Kidney Diseases

Background: Mitophagy is a crucial process involved in maintaining cellular homeostasis by selectively eliminating damaged or surplus mitochondria. As the kidney is an organ with a high dynamic metabolic rate and abundant mitochondria, it is particularly crucial to control mitochondrial quality through mitophagy. Dysregulation of mitophagy has been associated with various renal diseases, including acute and chronic kidney diseases, and therefore a better understanding of the links between mitophagy and these diseases may present new opportunities for therapeutic interventions. Summary: Mitophagy plays a pivotal role in the development of kidney diseases. Upregulation and downregulation of mitophagy have been observed in various kidney diseases, such as renal ischemia-reperfusion injury, contrast-induced acute kidney injury, diabetic nephropathy, kidney fibrosis, and several inherited renal diseases. A growing body of research has suggested that PINK1 and Parkin, the main mitophagy regulatory proteins, represent promising potential therapeutic targets for kidney diseases. In this review, we summarize the latest insights into how the progression of renal diseases can be mitigated through the regulation of mitophagy, while highlighting their performance in clinical trials. Key Message: This review comprehensively outlines the mechanisms of mitophagy and its role in numerous kidney diseases. While early research holds promise, most mitophagy-centered therapeutic approaches have yet to reach the clinical application stage.

APP-CD74 axis mediates endothelial cell-macrophage communication to promote kidney injury and fibrosis.

Kidney injuries often carry a grim prognosis, marked by fibrosis development, renal function loss, and macrophage involvement. Despite extensive research on macrophage polarization and its effects on other cells, like fibroblasts, limited attention has been paid to the influence of non-immune cells on macrophages. This study aims to address this gap by shedding light on the intricate dynamics and diversity of macrophages during renal injury and repair. During the initial research phase, the complexity of intercellular communication in the context of kidney injury was revealed using a publicly available single-cell RNA sequencing library of the unilateral ureteral obstruction (UUO) model. Subsequently, we confirmed our findings using an independent dataset from a renal ischemia-reperfusion injury (IRI) model. We treated two different types of endothelial cells with TGF-β and co-cultured their supernatants with macrophages, establishing an endothelial cell and macrophage co-culture system. We also established a UUO and an IRI mouse model. Western blot analysis, flow cytometry, immunohistochemistry and immunofluorescence staining were used to validate our results at multiple levels. Our analysis revealed significant changes in the heterogeneity of macrophage subsets during both injury processes. Amyloid β precursor protein (APP)-CD74 axis mediated endothelial-macrophage intercellular communication plays a dominant role. In the in vitro co-culture system, TGF-β triggers endothelial APP expression, which subsequently enhances CD74 expression in macrophages. Flow cytometry corroborated these findings. Additionally, APP and CD74 expression were significantly increased in the UUO and IRI mouse models. Immunofluorescence techniques demonstrated the co-localization of F4/80 and CD74 in vivo. Our study unravels a compelling molecular mechanism, elucidating how endothelium-mediated regulation shapes macrophage function during renal repair. The identified APP-CD74 signaling axis emerges as a promising target for optimizing renal recovery post-injury and preventing the progression of chronic kidney disease.

Establishment and characterization of a mouse model for studying kidney repair in diabetes.

The prognosis of acute kidney injury (AKI) is markedly worse in diabetic patients. Diabetes not only exaggerates the severity of AKI but may also prevent kidney repair or recovery from AKI. Little is known about the cellular and molecular basis of defective kidney repair in diabetes. One obstacle in studying kidney repair in diabetes is the lack of suitable animal models. Specifically, diabetes increases AKI severity, making it difficult to induce the same level of AKI in diabetic and non-diabetic animals to compare their kidney repair. Here, we have identified a time-window of 4 days immediately after the completion of streptozotocin (STZ) treatment in mice when blood glucose has yet to rise. Within this time-window, renal ischemia-reperfusion injury (IRI) induced the same level of AKI in STZ-treated mice [127.2±12.82 mg/dL blood urea nitrogen (BUN), 2.275±0.4728 serum creatinine] and vehicle solution-treated mice (128.6±11.83 mg/dL BUN, 2.087±0.4748 mg/dL serum creatinine]. By day 5-6, the post-AKI kidney entered into the phase of kidney repair when diabetic hyperglycemia started in STZ-treated mice, providing the opportunity to study the effect of diabetes on kidney repair without affecting initial AKI. In this model, kidney repair was indeed impaired by diabetes (116.5±8.052 mg/dL BUN and 1.382±0.2732 mg/dL serum creatinine in IR+vehicle group; 136.6±8.740 mg/dL BUN and 1.916±0.3756 mg/dL serum creatinine in IR+STZ group). The impairment was associated with decreased tubular cell proliferation and increased tubular cell senescence, peritubular capillary (PTC) rarefaction, inflammation, and 40.90% more interstitial fibrosis.

Canine mesenchymal stem cell-derived exosomes attenuate renal ischemia-reperfusion injury through miR-146a-regulated macrophage polarization.

The most common factor leading to renal failure or death is renal IR (ischemia-reperfusion). Studies have shown that mesenchymal stem cells (MSCs) and their exosomes have potential therapeutic effects for IR injury by inhibiting M1 macrophage polarization and inflammation. In this study, the protective effect and anti-inflammatory mechanism of adipose-derived mesenchymal stem cell-derived exosomes (ADMSC-Exos) after renal IR were investigated. Initially, ADMSC-Exos were intravenously injected into IR experimental beagles, and the subsequent assessment focused on inflammatory damage and macrophage phenotype. Furthermore, an in vitro inflammatory model was established by inducing DH82 cells with LPS. The impact on inflammation and macrophage phenotype was then evaluated using ADMSC and regulatory miR-146a. Following the administration of ADMSC-Exos in IR canines, a shift from M1 to M2 macrophage polarization was observed. Similarly, in vitro experiments demonstrated that ADMSC-Exos enhanced the transformation of LPS-induced macrophages from M1 to M2 type. Notably, the promotion of macrophage polarization by ADMSC-Exos was found to be attenuated upon the inhibition of miR-146a in ADMSC-Exos. These findings suggest that miR-146a plays a significant role in facilitating the transition of LPS-induced macrophages from M1 to M2 phenotype. As a result, the modulation of macrophage polarization by ADMSC-Exos is achieved via the encapsulation and conveyance of miR-146a, leading to diminished infiltration of inflammatory cells in renal tissue and mitigation of the inflammatory reaction following canine renal IR.

Identification of Renal Ischemia-Reperfusion Injury Subtypes and Predictive Model for Graft Loss after Kidney Transplantation Based on Programmed Cell Death-Related Genes

Introduction: Ischemia-reperfusion injury (IRI) is detrimental to kidney transplants and may contribute to poor long-term outcomes of transplantation. Programmed cell death (PCD), a regulated cell death form triggered by IRI, is often indicative of an unfavorable prognosis following transplantation. However, given the intricate pathophysiology of IRI and the considerable variability in clinical conditions during kidney transplantation, the specific patterns of cell death within renal tissues remain ambiguous. Consequently, accurately predicting the outcomes for transplanted kidneys continues to be a formidable challenge. Methods: Eight Gene Expression Omnibus datasets of biopsied transplanted kidney samples post-IRI and 1,548 PCD-related genes derived from 18 PCD patterns were collected in our study. Consensus clustering was performed to identify distinct IRI subtypes based on PCD features (IRI PCD subtypes). Differential enrichment analysis of cell death, metabolic signatures, and immune infiltration across these subtypes was evaluated. Three machine learning algorithms were used to identify PCD patterns related to prognosis. Genes associated with graft loss were screened for each PCD type. A predictive model for graft loss was constructed using 101 combinations of 10 machine learning algorithms. Results: Four IRI subtypes were identified: PCD-A, PCD-B, PCD-C, and PCD-D. PCD-A, characterized by high enrichment of multiple cell death patterns, significant metabolic paralysis, and immune infiltration, showed the poorest prognosis among the four subtypes. While PCD-D involved the least kind of cell death patterns with the features of extensive activation of metabolic pathways and the lowest immune infiltration, correlating with the best prognosis in the four subtypes. Using various machine learning algorithms, 10 cell death patterns and 42 PCD-related genes were identified as positively correlated with graft loss. The predictive model demonstrated high sensitivity and specificity, with area under the curve values for 0.5-, 1-, 2-, 3-, and 4-year graft survival at 0.888, 0.91, 0.926, 0.923, and 0.923, respectively. Conclusion: Our study explored the comprehensive features of PCD patterns in transplanted kidney samples post-IRI. The prediction model shows great promise in forecasting graft loss and could aid in risk stratification in patients following kidney transplantation.

Effect of Sodium Thiosulfate Pre-Treatment on Renal Ischemia-Reperfusion Injury in Kidney Transplantation.

We recently reported in a rat model of kidney transplantation that the addition of sodium thiosulfate (STS) to organ preservation solution improved renal graft quality and prolonged recipient survival. The present study investigates whether STS pre-treatment would produce a similar effect. In vitro, rat kidney epithelial cells were treated with 150 μM STS before and/or during exposure to hypoxia followed by reoxygenation. In vivo, donor rats were treated with PBS or 2.4 mg/kg STS 30 min before donor kidneys were procured and stored in UW or UW+150 μM STS solution at 4 °C for 24 h. Renal grafts were then transplanted into bilaterally nephrectomised recipient rats which were then sacrificed on post-operative day 3. STS pre-treatment significantly reduced cell death compared to untreated and other treated cells in vitro (p < 0.05), which corresponded with our in vivo result (p < 0.05). However, no significant differences were observed in other parameters of tissue injury. Our results suggest that STS pre-treatment may improve renal graft function after transplantation.

ANKRD1 aggravates renal ischaemia‒reperfusion injury via promoting TRIM25-mediated ubiquitination of ACSL3.

Renal ischaemia‒reperfusion injury (IRI) is the primary cause of acute kidney injury (AKI). To date, effective therapies for delaying renal IRI and postponing patient survival remain absent. Ankyrin repeat domain 1 (ANKRD1) has been implicated in some pathophysiologic processes, but its role in renal IRI has not been explored. The mouse model of IRI-AKI and in vitro model were utilised to investigate the role of ANKRD1. Immunoprecipitation-mass spectrometry was performed to identify potential ANKRD1-interacting proteins. Protein‒protein interactions and protein ubiquitination were examined using immunoprecipitation and proximity ligation assay and immunoblotting, respectively. Cell viability, damage and lipid peroxidation were evaluated using biochemical and cellular techniques. First, we unveiled that ANKRD1 were significantly elevated in renal IRI models. Global knockdown of ANKRD1 in all cell types of mouse kidney by recombinant adeno-associated virus (rAAV9)-mitigated ischaemia/reperfusion-induced renal damage and failure. Silencing ANKRD1 enhanced cell viability and alleviated cell damage in human renal proximal tubule cells exposed to hypoxia reoxygenation or hydrogen peroxide, while ANKRD1 overexpression had the opposite effect. Second, we discovered that ANKRD1's detrimental function during renal IRI involves promoting lipid peroxidation and ferroptosis by directly binding to and decreasing levels of acyl-coenzyme A synthetase long-chain family member 3 (ACSL3), a key protein in lipid metabolism. Furthermore, attenuating ACSL3 in vivo through pharmaceutical approach and in vitro via RNA interference mitigated the anti-ferroptotic effect of ANKRD1 knockdown. Finally, we showed ANKRD1 facilitated post-translational degradation of ACSL3 by modulating E3 ligase tripartite motif containing 25 (TRIM25) to catalyse K63-linked ubiquitination of ACSL3, thereby amplifying lipid peroxidation and ferroptosis, exacerbating renal injury. Our study revealed a previously unknown function of ANKRD1 in renal IRI. By driving ACSL3 ubiquitination and degradation, ANKRD1 aggravates ferroptosis and ultimately exacerbates IRI-AKI, underlining ANKRD1's potential as a therapeutic target for kidney IRI. Ankyrin repeat domain 1 (ANKRD1) is rapidly activated in renal ischaemia‒reperfusion injury (IRI) models in vivo and in vitro. ANKRD1 knockdown mitigates kidney damage and preserves renal function. Ferroptosis contributes to the deteriorating function of ANKRD1 in renal IRI. ANKRD1 promotes acyl-coenzyme A synthetase long-chain family member 3 (ACSL3) degradation via the ubiquitin‒proteasome pathway. The E3 ligase tripartite motif containing 25 (TRIM25) is responsible for ANKRD1-mediated ubiquitination of ACSL3.

MicroRNA-223 alleviates inflammatory response in renal ischemia-reperfusion injury by targeting NLRP3.

We investigated the potential correlation between miR-223 and NAcHT, LRR, and PYd domain-containing protein 3 (NLRP3) in the context of renal ischemia-reperfusion injury (RIRI), which is a leading cause of acute renal failure with significant mortality rates. Additionally, miR-223 has been implicated in renal inflammation, further highlighting its relevance to this study. C57BL/6 male mice were used as RIRI models. After successful modeling, pathological examinations and serum creatinine and miR-223 levels were tested. Pro-inflammatory cytokine (IL-1β, IL-6, IL-8, NLPR3, TLR4) expression was detected in mice by western blot (kidney tissue) and enzyme-linked immunosorbent assay (serum). HK-2 cells were used for in vitro experiments. A hypoxia/reoxygenation (H/R) model was used, and miR-223 and pro-inflammatory cytokine levels were detected using PCR and western blot assays, respectively. A dual-luciferase reporter assay was conducted to confirm the binding of miR-223 to NLPR3. Next, NLRP3 was knocked down to determine whether the anti-inflammatory function of miR-223 is dependent on NLRP3. MiR-223 expression was lower in RIRI mice than in the sham operation group. The level of miR-223 negatively correlated with serum creatinine levels and the severity of tubule injury. Increased proinflammatory cytokine levels in RIRI mice were observed. In vitro, miR-223 alleviated the inflammatory response in H/R treated cells by inhibiting proinflammatory cytokines. Dual-luciferase reporter and western blot assays confirmed the binding of miR-223 to NLRP3. NLRP3 knockdown reversed the anti-inflammatory effects of miR-223 in HK-2 cells. MiR-223 plays an anti-inflammatory role in RIRI by targeting NLRP3 to repress pro-inflammatory factors.

P.066: Expression and effect of Pbrm1 in renal ischemia-reperfusion injury.

P.066: Expression and effect of Pbrm1 in renal ischemia-reperfusion injury.

228.4: Treatment with a specific inhibitor of the complement lectin pathway is protective against renal ischemia-reperfusion injury in mice.

228.4: Treatment with a specific inhibitor of the complement lectin pathway is protective against renal ischemia-reperfusion injury in mice.

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

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

AST-120 alleviates renal ischemia-reperfusion injury by inhibiting HK2-mediated glycolysis

ObjectiveRenal ischemia/reperfusion injury (IRI) is a major cause of acute kidney injury (AKI), which is associated with high incidence and mortality. AST-120 is an oral carbonaceous adsorbent that can alleviate kidney damage. This study aimed to explore the effects of AST-120 on renal IRI and the molecular mechanism.MethodsA renal IRI mouse model was established and administrated AST-120, and differentially expressed genes were screened using RNA sequencing. Renal function and pathology were analyzed in mice. Hypoxia/reoxygenation (H/R) cell model was generated, and glycolysis was evaluated by detecting lactate levels and Seahorse analysis. Histone lactylation was analyzed by western blotting, and its relationship with hexokinase 2 (HK2) was assessed using chromatin immunoprecipitation.ResultsThe results showed that HK2 expression was increased after IRI, and AST-120 decreased HK2 expression. Knockout of HK2 attenuated renal IRI and inhibits glycolysis. AST-120 inhibited renal IRI in the presence of HK2 rather than HK2 absence. In proximal tubular cells, knockdown of HK2 suppressed glycolysis and H3K18 lactylation caused by H/R. H3K18 lactylation was enriched in HK2 promoter and upregulated HK2 levels. Rescue experiments revealed that lactate reversed IRI that suppressed by HK2 knockdown.ConclusionsIn conclusion, AST-120 alleviates renal IRI via suppressing HK2-mediated glycolysis, which suppresses H3K18 lactylation and further reduces HK2 levels. This study proposes a novel mechanism by which AST-120 alleviates IRI.

Renal protective effects of helix B surface polypeptide in rats with puromycin aminonucleoside nephropathy

Background Recent studies have reported that helix B surface polypeptide (HBSP), an erythropoietin derivative, exhibits strong tissue protective effects, independent of erythropoietic effects, in a renal ischemia-reperfusion (IR) injury model. Meanwhile, the transforming growth factor-β (TGF-β) superfamily member glial cell line-derived neurotrophic factor (GDNF) demonstrated protective effect on podocytes in vitro. Using a rat puromycin aminonucleoside nephropathy (PAN) model, this study observed the renal protective effect of HBSP and investigated its renal protective effect on podocytes and mechanism related to GDNF. Methods Rats nephropathy model was induced by injection of 60 mg/kg of PAN via the tail vein. Rats in the PAN + HBSP group were injected intraperitoneally with HBSP (8 nmol/kg) 4 h before the model was induced, followed by intraperitoneal injections of HBSP once every 24 h for 7 consecutive days. The 24-hour urinary protein level was measured once every other day, and blood and renal tissue samples were collected on the 7th day for the examination of renal function, complete blood count, renal pathological changes and the expression levels of GDNF. Results Compared with the control group, the PAN nephropathy rat model showed a large amount of urinary protein. The pathological manifestations were mainly extensive fusion and disappearance of foot processes, along with vacuolar degeneration of podocytes and their separation from the glomerular basement membrane. GDNF expression was upregulated. Compared with the PAN + vehicle group, the PAN + HBSP group showed decreased urinary protein (p < 0.05). Pathological examination revealed ameliorated glomerular injury and vacuolar degeneration of podocytes. The expression of GDNF in the PAN nephropathy group was increased, when compared with the control group. The greatest expression of GDNF observed in the PAN + HBSP group (p < 0.05). Conclusions The expression of GDNF in the kidney of PAN rat model was increased. HBSP reduced urinary protein, ameliorated pathological changes in renal podocytes, increased the expression of GDNF in the PAN rat model. HBSP is likely to exert its protective effects on podocytes through upregulation of GDNF expression.

ST2 + T-Regulatory Cells in Renal Inflammation and Fibrosis after Ischemic Kidney Injury.

Inflammation is a major cause of kidney injury. The Interleukin (IL)-1 family cytokine IL-33 is released from damaged cells and modulates the immune response through its receptor ST2 expressed on many cell types, including regulatory T-cells (Tregs). While a proinflammatory role of IL-33 has been proposed, exogenous IL-33 expanded Tregs and suppressed renal inflammation. However, the contribution of endogenous IL-33/ST2 for the role of Tregs in the resolution of kidney injury has not been investigated. We used murine renal ischemia-reperfusion injury and kidney organoids to delineate the role of the ST2 and amphiregulin (AREG) specifically in Treg cells using targeted deletion. Bulk and single-cell RNA sequencing was performed on flow-sorted Tregs from spleen and CD4 T-cells from post-ischemic kidneys respectively. The protective role of ST2-sufficient Tregs was analyzed using a novel co-culture system of syngeneic kidney organoids and Treg cells under hypoxic conditions. Bulk RNA-sequencing of splenic and single-cell-RNA-sequencing of kidney T-cells showed that ST2+ Tregs are enriched for genes related to Treg proliferation and function. Genes for reparative factors such as AREG were also enriched in ST2+ Tregs. Treg-specific deletion of ST2 or AREG exacerbated kidney injury and fibrosis in the unilateral ischemia reperfusion injury model. In co-culture studies, WT but not ST2-deficient Tregs preserved the hypoxia-induced loss of kidney-organoid viability, which was restored by AREG supplementation. Our study identified the role of the IL-33/ST2 pathway in Tregs for resolution of kidney injury. The transcriptome of ST2+ Tregs was enriched for reparative factors including AREG. Lack of ST2 or AREG in Tregs worsened kidney injury. Tregs protected kidney organoids from hypoxia in ST2 and AREG-dependent manner. Thus Treg-based approaches could be of benefit for resolution of renal injury.

Ligustilide alleviates oxidative stress during renal ischemia-reperfusion injury through maintaining Sirt3-dependent mitochondrial homeostasis

BackgroundRenal ischemia-reperfusion (I/R) injury is an inevitable complication during renal transplantation and is closely related to patient prognosis. Mitochondrial damage induced oxidative stress is the core link of renal I/R injury. Ligustilide (LIG), a natural compound extracted from ligusticum chuanxiong hort and angelica sinensis, has exhibited the potential to protect mitochondrial function. However, whether LIG can ameliorate renal I/R injury requires further investigation. Delving deeper into the precise targets and mechanisms of LIG's effect on renal I/R injury is crucial. PurposeThis study aimed to elucidate the specific mechanism of LIG's protective effect on renal I/R injury. MethodsIn this study, an in vivo model of renal ischemia-reperfusion (I/R) injury was developed in mice, along with an in vitro model of hypoxia-reoxygenation (H/R) using human proximal renal tubular epithelial cells (HK-2). To assess the impact of LIG on renal injury, various methods were employed, including serum creatinine (Cr) and blood urea nitrogen (BUN) testing, hematoxylin and eosin (HE) staining, and immunohistochemistry (IHC) for kidney injury molecule-1 (KIM-1). The effects of LIG on oxidative stress were examined using fluorescent probes dihydroethidium (DHE) and dichlorodihydrofluorescein diacetate (DCFH-DA), TdT-mediated dUTP Nick-End Labeling (TUNEL) staining, and flow cytometry. Additionally, the influence of LIG on mitochondrial morphology and function was evaluated through transmission electron microscopy (TEM), Mito Tracker Red CMXRos staining, adenosine triphosphate (ATP) concentration assays, and JC-1 staining. The potential mechanism involving LIG and Sirt3 was explored by manipulating Sirt3 expression through cell transfection. ResultsThe results showed that LIG could provide protective function for mitochondria to alleviate oxidative stress induced by renal I/R. Further mechanistic studies indicated that LIG maintained mitochondrial homeostasis by targeting Sirt3. ConclusionOur findings demonstrated that LIG alleviated oxidative stress during renal I/R injury through maintaining Sirt3-dependent mitochondrial homeostasis. Overall, our data raised the possibility of LIG as a novel therapy for renal I/R injury.

Canagliflozin Mitigates Acute Kidney Injury Secondary to Resuscitative Endovascular Balloon Occlusion of the Aorta in a Porcine Model of Hemorrhagic Shock.

We investigated the potential of acute canagliflozin administration to mitigate acute kidney injury (AKI) and attenuate deleterious pro-inflammatory cytokine release in a clinically relevant swine model of severe renal ischemia reperfusion injury (IRI) induced by hemorrhage and aortic occlusion. Long-term canagliflozin use attenuates renal function decline and reduces AKI in diabetes mellitus and heart failure patients. Whilst several reports indicate prophylactic SGLT2 inhibition prevents AKI in IRI, the efficacy of acute administration on IRI and inflammation is not known. Female swine (n=16) underwent controlled hemorrhage of 25% blood volume, followed by 90 min of aortic occlusion at the level of the renal ostia (via Resuscitative Endovascular Balloon Occlusion of the Aorta). A single 300mg dose of oral canagliflozin or vehicle (saline) was delivered 5 mins into aortic occlusion. Hemodynamic monitoring, markers of renal function (serum creatinine, blood urea nitrogen, proteinuria and urinary neutrophil gelatinase-associated lipocalin) and serum cytokine concentrations (including interleukins: IL-1RA, IL-6, IL-8, IL-10, IL-18; and Tumor necrosis factor alpha) were analyzed after IRI, and during a 6h critical care phase. Compared to controls, animals receiving canagliflozin had less severe AKI, improved creatinine clearance, reduced proteinuria, and significantly lower tubular damage as evidenced by histopathology and urinary NGAL. Furthermore, the pro-inflammatory cytokine IL-6 was markedly attenuated without reduction in anti-inflammatory cytokines (IL-1RA and IL-10). A single dose of canagliflozin administered shortly into ischemic insult mitigates AKI and attenuates harmful pro-inflammatory cytokine release following trauma or surgery. These findings suggest a potential novel therapeutic role for canagliflozin in mitigating the effects of renal IRI worthy of further investigation.