Mouse model of ischemic acute kidney injury: technical notes and tricks

Protective effect and mechanism of Xiaoyu Xiezhuo decoction on ischemia-reperfusion induced acute kidney injury based on gut-kidney crosstalk

This study aimed to explore the mechanism of Xiaoyu Xiezhuo decoction (XXD) on ischemia-reperfusion-induced acute kidney injury (IRI-AKI) using network pharmacology methods and gut microbiota analysis. A total of 1778 AKI-related targets were obtained, including 140 targets possibly regulated by AKI in XXD, indicating that the core targets were mainly enriched in inflammatory-related pathways, such as the IL-17 signaling pathway and TNF signaling pathway. The unilateral IRI-AKI animal model was established and randomly divided into four groups: the sham group, the AKI group, the sham + XXD group, and the AKI + XXD group. Compared with the rats in the AKI group, XXD improved not only renal function, urinary enzymes, and biomarkers of renal damage such as Kim-1, cystatin C, and serum inflammatory factors such as IL-17, TNF-α, IL-6, and IL 1-β, but also intestinal metabolites including lipopolysaccharides, d-lactic acid, indoxyl sulfate, p-cresyl sulfate, and short-chain fatty acids. XXD ameliorated renal and colonic pathological injury as well as inflammation and chemokine gene abundance, such as IL-17, TNF-α, IL-6, IL-1β, ICAM-1, and MCP-1, in AKI rats via the TLR4/NF-κB/NLRP3 pathway, reducing the AKI score, renal pathological damage, and improving the intestinal mucosa's inflammatory infiltration. It also repaired markers of the mucosal barrier, including claudin-1, occludin, and ZO-1. Compared with the rats in the AKI group, the α diversity was significantly increased, and the Chao1 index was significantly enhanced after XXD treatment in both the sham group and the AKI group. The treatment group significantly reversed this change in microbiota.

The novel potential therapeutic target PSMP/MSMP promotes acute kidney injury via CCR2

Acute kidney injury (AKI) is a major worldwide health concern that currently lacks effective medical treatments. PSMP is a damage-induced chemotactic cytokine that acts as a ligand of CCR2 and has an unknown role in AKI. We have observed a significant increase in PSMP levels in the renal tissue, urine, and plasma of patients with AKI. PSMP deficiency improved kidney function and decreased tubular damage and inflammation in AKI mouse models induced by kidney ischemia-reperfusion injury, glycerol, and cisplatin. Single-cell RNA sequencing analysis revealed that Ly6Chi or F4/80lo infiltrated macrophages (IMs) were a major group of proinflammatory macrophages with strong CCR2 expression in AKI. We observed that PSMP deficiency decreased CCR2+Ly6Chi or F4/80lo IMs and inhibited M1 polarization in the AKI mouse model. Moreover, overexpressed human PSMP in the mouse kidney could reverse the attenuation of kidney injury in a CCR2-dependent manner, and this effect could be achieved without CCL2 involvement. Extracellular PSMP played a crucial role, and treatment with a PSMP-neutralizing antibody significantly reduced kidney injury in vivo. Therefore, PSMP might be a therapeutic target for AKI, and its antibody is a promising therapeutic drug for the treatment of AKI.

Ultrasound molecular imaging for early detection of acute renal ischemia-reperfusion injury

Background

Microcirculatory perfusion disorder and inflammatory response are critical links in acute kidney injury (AKI). We aim to construct anti-vascular cell adhesion molecule-1(VCAM-1) targeted microbubbles (TM) to monitor renal microcirculatory perfusion and inflammatory response.

Methods

TM carrying VCAM-1 polypeptide was constructed by biological coupling. The binding ability of TM to human umbilical vein endothelial cells (HUVECs) was detected. Bilateral renal ischemia-reperfusion injury (IRI) models of mice were established to evaluate microcirculatory perfusion and inflammatory response using TM. Thirty-six mice were randomly divided into six groups according to the different reperfusion time (0.5, 2, 6, 12, and 24 h) and sham-operated group (Sham group). The correlation of TM imaging with serum and histopathological biomarkers was investigated.

Results

TM has advantages such as uniform distribution, regular shape, high stability, and good biosafety. TM could bind specifically to VCAM-1 molecule expressed by tumor necrosis factor-alpha (TNF-α)-treated HUVECs. In the renal IRI-AKI model, the area under the curve (AUC) of TM significantly decreased both in the renal cortical and medullary after 2 h of reperfusion compared with the Sham group (p < 0.05). Normalized intensity difference (NID) of TM at different reperfusion time was all higher than that of blank microbubbles (BM) and the Sham group (p < 0.05). Ultrasound molecular imaging of TM could detect AKI early before commonly used renal function markers, histopathological biomarkers, and BM imaging. AUC of TM was negatively correlated with serum creatinine (Scr), blood urea nitrogen (BUN), and Cystatin C (Cys-C) levels, and NID of TM was linearly correlated with VCAM-1, TNF-α, and interleukin-6 (IL-6) expression (p < 0.05).

Conclusions

Ultrasound molecular imaging based on TM carrying VCAM-1 polypeptide can accurately evaluate the changes in renal microcirculatory perfusion and inflammatory response, which might be a promising modality for early diagnosis of AKI.

An integrated view of cisplatin-induced nephrotoxicity, hepatotoxicity, and cardiotoxicity: characteristics, common molecular mechanisms, and current clinical management

Cisplatin (CP) is a chemotherapy drug widely prescribed to treat various neoplasms. Although fundamental for the therapeutic action of the drug, its cytotoxic mechanisms trigger adverse effects in several tissues, such as the kidney, liver, and heart, which limit its clinical use. In this sense, studies point to an essential role of damage to nuclear and mitochondrial DNA associated with oxidative stress, inflammation, and apoptosis in the pathophysiology of tissue injuries. Due to the limitation of effective preventive and therapeutic measures against CP-induced toxicity, new strategies with potential cytoprotective effects have been studied. Therefore, this article is timely in reviewing the characteristics and main molecular mechanisms common to renal, hepatic, and cardiac toxicity previously described, in addition to addressing the main validated strategies for the current management of these adverse events in clinical practice. We also handle the main promising antioxidant substances recently presented in the literature to encourage the development of new research that consolidates their potential preventive and therapeutic effects against CP-induced cytotoxicity.

Rodent models of AKI and AKI-CKD transition: an update in 2024

Despite known drawbacks, rodent models are essential tools in the research of renal development, physiology, and pathogenesis. In the past decade, rodent models have been developed and used to mimic different etiologies of acute kidney injury (AKI), AKI to chronic kidney disease (CKD) transition or progression, and AKI with comorbidities. These models have been applied for both mechanistic research and preclinical drug development. However, current rodent models have their limitations, especially since they often do not fully recapitulate the pathophysiology of AKI in human patients, and thus need further refinement. Here, we discuss the present status of these rodent models, including the pathophysiologic compatibility, clinical translational significance, key factors affecting model consistency, and their main limitations. Future efforts should focus on establishing robust models that simulate the major clinical and molecular phenotypes of human AKI and its progression.

Combined Plasma Olink Proteomics and Transcriptomics Identifies CXCL1 and TNFRSF12A as Potential Predictive and Diagnostic Inflammatory Markers for Acute Kidney Injury

Acute kidney injury (AKI) poses a significant global public health challenge. Current methods for detecting AKI rely on monitoring changes in serum creatinine (Scr), blood urea nitrogen (BUN), urinary output and some commonly employed biomarkers. However, these indicators are usually neither specific nor sensitive to AKI, especially in cases of mild kidney injury. AKI is accompanied by severe inflammatory reactions, resulting in the upregulation of numerous inflammation-associated proteins in the plasma. Plasma biomarkers are a noninvasive method for detecting kidney injury, and to date, plasma inflammation-associated cytokines have not been adequately studied in AKI patients. The objective of our research was to identify novel inflammatory biomarkers for AKI. We utilized Olink proteomics to analyze the alterations in plasma inflammation-related proteins in the serum of healthy mice (n = 2) or mice treated with cisplatin (n = 6). Additionally, transcriptome datasets for the lipopolysaccharide (LPS), cisplatin, and ischemia‒reperfusion injury (IRI) groups were obtained from the National Center of Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) database. We calculated the intersection of differentially expressed proteins (DEPs) and genes (DEGs) from both datasets. In the Olink proteomics analysis, the AKI group had significantly greater levels of 11 DEPs than did the control group. In addition, 56 common upregulated DEGs were obtained from the transcriptome dataset. The expression of CXCL1 and TNFRSF12A overlapped across all the datasets. The transcription and protein expression levels of CXCL1 and TNFRSF12A were detected in vivo. The gene and protein levels of CXCL1 and TNFRSF12A were significantly increased in different AKI mouse models and clinical patients, suggesting that these genes and proteins could be potential specific biomarkers for the identification of AKI.

Comprehensive molecular and cellular characterization of endoplasmic reticulum stress-related key genes in renal ischemia/reperfusion injury

Background

Renal ischemia-reperfusion injury (RIRI) is an inevitable complication in the process of kidney transplantation and lacks specific therapy. The study aims to determine the underlying mechanisms of RIRI to uncover a promising target for efficient renoprotection.

Method

Four bulk RNA-seq datasets including 495 renal samples of pre- and post-reperfusion were collected from the GEO database. The machine learning algorithms were utilized to ascertain pivotal endoplasmic reticulum stress genes. Then, we incorporated correlation analysis and determined the interaction pathways of these key genes. Considering the heterogeneous nature of bulk-RNA analysis, the single-cell RNA-seq analysis was performed to investigate the mechanisms of key genes at the single-cell level. Besides, 4-PBA was applied to inhibit endoplasmic reticulum stress and hence validate the pathological role of these key genes in RIRI. Finally, three clinical datasets with transcriptomic profiles were used to assess the prognostic role of these key genes in renal allograft outcomes after RIRI.

Results

In the bulk-RNA analysis, endoplasmic reticulum stress was identified as the top enriched pathway and three endoplasmic reticulum stress-related genes (PPP1R15A, JUN, and ATF3) were ranked as top performers in both LASSO and Boruta analyses. The three genes were found to significantly interact with kidney injury-related pathways, including apoptosis, inflammatory response, oxidative stress, and pyroptosis. For oxidative stress, these genes were more strongly related to oxidative markers compared with antioxidant markers. In single-cell transcriptome, the three genes were primarily upregulated in endothelium, distal convoluted tubule cells, and collecting duct principal cells among 12 cell types of renal tissues in RIRI. Furthermore, distal convoluted tubule cells and collecting duct principal cells exhibited pro-inflammatory status and the highest pyroptosis levels, suggesting their potential as main effectors of three key genes for mediating RIRI-associated injuries. Importantly, inhibition of these key genes using 4-phenyl butyric acid alleviated functional and histological damage in a mouse RIRI model. Finally, the three genes demonstrated highly prognostic value in predicting graft survival outcomes.

Conclusion

The study identified three key endoplasmic reticulum stress-related genes and demonstrated their prognostic value for graft survival, providing references for individualized clinical prevention and treatment of postoperative complications after renal transplantation.

SGLT2 inhibition promotes glomerular repopulation by cells of renin lineage in experimental kidney disease

AIM

Sodium glucose co-transporter-2 (SGLT2) inhibitors stimulate renal excretion of sodium and glucose and exert renal protective effects in patients with (non-)diabetic chronic kidney disease (CKD) and may as well protect against acute kidney injury (AKI). The mechanism behind this kidney protective effect remains unclear. Juxtaglomerular cells of renin lineage (CoRL) have been demonstrated to function as progenitors for multiple adult glomerular cell types in kidney disease. This study assesses the impact of SGLT2 inhibition on the repopulation of glomerular cells by CoRL and examines their phenotypic commitment.

METHODS

Experiments were performed in Ren1cre-tdTomato lineage-trace mice. Either 5/6 nephrectomy (5/6NX) modeling CKD or bilateral ischaemia reperfusion injury (bIRI) mimicking AKI was applied, while the SGLT2 inhibitor empagliflozin (10 mg/kg) was administered daily via oral gavage for 14 days.

RESULTS

Both 5/6NX and bIRI-induced kidney injury increased the number of glomerular CoRL-derived cells. SGLT2 inhibition improved kidney function after 5/6NX, indicated by decreased blood creatinine and urea levels, but not after bIRI. In line with this, empagliflozin in 5/6NX animals resulted in less glomerulosclerosis, while it did not affect histopathological features in bIRI. Treatment with empagliflozin resulted in an increase in the number of CoRL-derived glomerular cells in both 5/6NX and bIRI conditions. Interestingly, SGLT2 inhibition led to more CoRL-derived podocytes in 5/6NX animals, whereas empagliflozin-treated bIRI mice presented with increased levels of parietal epithelial and mesangial cells derived from CoRL.

CONCLUSION

We conclude that SGLT2 inhibition by empagliflozin promotes CoRL-mediated glomerular repopulation with selective CoRL-derived cell types depending on the type of experimental kidney injury. These findings suggest a previously unidentified mechanism that could contribute to the renoprotective effect of SGLT2 inhibitors.

Loss of nephric augmenter of liver regeneration facilitates acute kidney injury via ACSL4-mediated ferroptosis

Ferroptosis, characterized by lipid accumulation in intracellular compartments, is related to acute kidney injury (AKI), but the mechanism remains obscure. In our previous study, the protective effect of augmenter of liver regeneration (ALR) on AKI was not fully clarified. In this study, we established an AKI mouse model by knocking out proximal tubule-specific ALR and an AKI cell model by inducing hypoxia, as well as enrolled AKI patients, to investigate the effects of ALR on ferroptosis and the progression of AKI. We found that ALR knockout aggravated ferroptosis and increased ROS accumulation and mitochondrial damage, whereas ALR overexpression attenuated ferroptosis through clearance of ROS and maintenance of mitochondrial morphology. Mechanistically, we demonstrated that ALR could directly bind to long-chain-fatty-acid-CoA ligase 4 (ACSL4) and further inhibit the expression of ACSL4 by interacting with certain regions. By resolution liquid chromatography coupled with triple quadruple mass spectrometry, we found that ALR could reduce the contents of polyunsaturated fatty acids, especially arachidonic acid. In addition, we showed that ALR binds to ACSL4 and attenuates oxylipin accumulation, exerting a protective effect against ferroptosis in AKI. Therefore, targeting renal ALR can attenuate ferroptosis and can offer a promising strategy for the treatment of AKI.

Bioinformatics analysis and experimental validation reveal the anti-ferroptosis effect of FZD7 in acute kidney injury

BACKGROUND

Ferroptosis plays an important role in acute kidney injury (AKI), but the specific regulatory mechanism of ferroptosis in AKI remains unclear. This study is expected to analyze ferroptosis-related genes (FRGs) in AKI and explore their underlying mechanisms.

RESULTS

A total of 479 differentially expressed genes (DEGs), including 196 up-regulated genes and 283 down-regulated genes were identified in the AKI chip GSE30718. 341 FRGs were obtained from the Genecard, OMIM and NCBI database. Totally 11 ferroptosis-related DEGs in AKI were found, in which 7 genes (CD44, TIGAR, RB1, LCN2, JUN, ARNTL, ACSL4) were up-regulated and 4 genes (FZD7, EP300, FOXC1, DLST) were down-regulated. Three core genes (FZD7, JUN, EP300) were obtained by PPI and KEGG analysis, among which the function of FZD7 in AKI is unclear. The WGCNA analysis found that FZD7 belongs to a module that was negatively correlated with AKI. Further basic experiments confirmed that FZD7 is down-regulated in mouse model of ischemia-reperfusion-AKI and cellular model of hypoxia-reoxygenation(H/R). In addition, knockdown of FZD7 could further aggravate the down-regulation of cell viability induced by H/R and Erastin, while overexpression of FZD7 can rescue its down-regulation to some extent. Furthermore, we verified that knockdown of FZD7 decreased the expression of GPX4 and overexpression of FZD7 increased the expression of GPX4, suggesting that FZD7 may inhibit ferroptosis by regulating the expression of GPX4 and plays a vital role in the onset and development of AKI.

CONCLUSIONS

This article revealed the anti-ferroptosis effect of FZD7 in acute kidney injury through bioinformatics analysis and experimental validation, suggesting that FZD7 is a promising target for AKI and provided more evidence about the vital role of ferroptosis in AKI.

Animal Models of Kidney Disease: Challenges and Perspectives

Kidney disease is highly prevalent and affects approximately 850 million people worldwide. It is also associated with high morbidity and mortality, and current therapies are incurable and often ineffective. Animal models are indispensable for understanding the pathophysiology of various kidney diseases and for preclinically testing novel remedies. In the last two decades, rodents continue to be the most used models for imitating human kidney diseases, largely because of the increasing availability of many unique genetically modified mice. Despite many limitations and pitfalls, animal models play an essential and irreplaceable role in gaining novel insights into the mechanisms, pathologies, and therapeutic targets of kidney disease. In this review, we highlight commonly used animal models of kidney diseases by focusing on experimental AKI, CKD, and diabetic kidney disease. We briefly summarize the pathological characteristics, advantages, and drawbacks of some widely used models. Emerging animal models such as mini pig, salamander, zebrafish, and drosophila, as well as human-derived kidney organoids and kidney-on-a-chip are also discussed. Undoubtedly, careful selection and utilization of appropriate animal models is of vital importance in deciphering the mechanisms underlying nephropathies and evaluating the efficacy of new treatment options. Such studies will provide a solid foundation for future diagnosis, prevention, and treatment of human kidney diseases.

MiR-132-3p activation aggravates renal ischemia-reperfusion injury by targeting Sirt1/PGC1alpha axis

The pathogenesis of renal ischemic diseases remains unclear. In this study, we demonstrate the induction of microRNA-132-3p (miR-132-3p) in ischemic acute kidney injury (AKI) and cultured renal tubular cells under oxidative stress. miR-132-3p mimic increased apoptosis in renal tubular cells and enhanced ischemic AKI in mice, whereas miR-132-3p inhibition offered protective effects. We analyzed miR-132-3p target genes through bioinformatic analysis and Sirt1 was predicted as the target gene of miR-132-3p. Luciferase microRNA target reporter assay further verified Sirt1 as a direct target of miR-132-3p. In cultured tubular cells and mouse kidneys, IRI and H2O2 treatment repressed Sirt1 and PGC-1α/NRF2/HO-1 expression, whereas anti-miR-132-3p preserved Sirt1 and PGC-1α/NRF2/HO-1 expression. In renal tubular, Sirt1 inhibitor suppressed PGC1-1α/NRF2/HO-1 expression and aggravated tubular apoptosis. Together, the results suggest that miR-132-3p induction aggravates ischemic AKI and oxidative stress by repressing Sirt1 expression, and miR-132-3p inhibition offers renal protection and may be a potential therapeutic target.

Cucurbit[8]uril-based water-dispersible assemblies with enhanced optoacoustic performance for multispectral optoacoustic imaging

Organic small-molecule contrast agents have attracted considerable attention in the field of multispectral optoacoustic imaging, but their weak optoacoustic performance resulted from relatively low extinction coefficient and poor water solubility restrains their widespread applications. Herein, we address these limitations by constructing supramolecular assemblies based on cucurbit[8]uril (CB[8]). Two dixanthene-based chromophores (DXP and DXBTZ) are synthesized as the model guest compounds, and then included in CB[8] to prepare host-guest complexes. The obtained DXP-CB[8] and DXBTZ-CB[8] display red-shifted and increased absorption as well as decreased fluorescence, thereby leading to a substantial enhancement in optoacoustic performance. Biological application potential of DXBTZ-CB[8] is investigated after co-assembly with chondroitin sulfate A (CSA). Benefiting from the excellent optoacoustic property of DXBTZ-CB[8] and the CD44-targeting feature of CSA, the formulated DXBTZ-CB[8]/CSA can effectively detect and diagnose subcutaneous tumors, orthotopic bladder tumors, lymphatic metastasis of tumors and ischemia/reperfusion-induced acute kidney injury in mouse models with multispectral optoacoustic imaging.

Role of Iberin as an anti-apoptotic agent on renal ischemia-reperfusion injury in rats

Ischemia-reperfusion injury (IRI) is a major contributor to acute and chronic kidney failure, heart failure, and ischemic stroke. This study aimed to investigate the therapeutic potential of Iberin, known for its anti-inflammatory, antioxidant, and antiapoptotic properties, in a rat model of renal IRI. Twenty-four adult male rats were randomly divided into four groups: Group I (Sham group) underwent laparotomy without IRI induction; Group II (Control group) underwent laparotomy followed by renal artery clamping for 30 minutes to induce ischemia, followed by 2 hours of reperfusion; Group III (Iberin treatment group) received a pre-injection of Iberin (15 mg/kg) and underwent 30 minutes of ischemia followed by 2 hours of reperfusion; and Group IV (Vehicle-treated group) received the vehicle (ethanol) 1 hour prior to ischemia and reperfusion induction. Iberin was diluted with ethanol. Biomarkers associated with inflammation, oxidative stress, and apoptosis were measured using enzyme-linked immunosorbent assay. Iberin treatment significantly reduced levels of inflammatory cytokines interleukin-1β (IL-1β) and IL-6, Bcl-2-associated X protein (BAX), tumor necrosis factor α (TNF-α), nuclear factor kappa p56, high mobility group B1, and neutrophil gelatinase-associated lipocalin. Moreover, Iberin increased levels of heat shock protein and Bcl2 compared to the control and vehicle groups. Iberin treatment prolonged the ischemic tolerance of renal tissue, potentially preventing or delaying irreversible injuries. These findings highlight the potential of Iberin as a promising candidate for mitigating renal injury caused by ischemia-reperfusion, due to its ability to modulate inflammatory markers.

Limonin, a natural ERK2 agonist, protects against ischemic acute kidney injury

Acute kidney injury (AKI) is a refractory clinical syndrome with limited effective treatments. Amid AKI, activation of the extracellular signal-regulated kinase (ERK) cascade plays a critical role in promoting kidney repair and regeneration. However, a mature ERK agonist in treating kidney disease remains lacking. This study identified limonin, a member of the class of compounds known as furanolactones, as a natural ERK2 activator. Employing a multidisciplinary approach, we systemically dissected how limonin mitigates AKI. Compared to vehicles, pretreatment of limonin significantly preserved kidney functions after ischemic AKI. We revealed that ERK2 is a significant protein linked to the limonin's active binding sites through structural analysis. The molecular docking study showed a high binding affinity between limonin and ERK2, which was confirmed by the cellular thermal shift assay and microscale thermophoresis. Mechanistically, we further validated that limonin promoted tubular cell proliferation and reduced cell apoptosis after AKI by activating ERK signaling pathway in vivo. In vitro and ex vivo, blockade of ERK abolished limonin's capacity of preventing tubular cell death under hypoxia stress. Our results indicated that limonin is a novel ERK2 activator with strong translational potential in preventing or mitigating AKI.

In vivo imaging of renal microvasculature in a murine ischemia-reperfusion injury model using optical coherence tomography angiography

Optical coherence tomography angiography (OCTA) provides three-dimensional structural and semiquantitative imaging of microvasculature in vivo. We developed an OCTA imaging protocol for a murine kidney ischemia-reperfusion injury (IRI) model to investigate the correlation between renal microvascular changes and ischemic damage. Mice were divided into mild and moderate IRI groups according to the duration of ischemia (10 and 35 mins, respectively). Each animal was imaged at baseline; during ischemia; and at 1, 15, 30, 45, and 60 mins after ischemia. Amplitude decorrelation OCTA images were constructed with 1.5-, 3.0-, and 5.8-ms interscan times, to calculate the semiquantitative flow index in the superficial (50-70 μm) and the deep (220-340 μm) capillaries of the renal cortex. The mild IRI group showed no significant flow index change in both the superfial and the deep layers. The moderate IRI group showed a significantly decreased flow index from 15 and 45 mins in the superficial and deep layers, respectively. Seven weeks after IRI induction, the moderate IRI group showed lower kidney function and higher collagen deposition than the mild IRI group. OCTA imaging of the murine IRI model revealed changes in superficial blood flow after ischemic injury. A more pronounced decrease in superficial blood flow than in deep blood flow was associated with sustained dysfunction after IRI. Further investigation on post-IRI renal microvascular response using OCTA may improve our understanding of the relationship between the degree of ischemic insult and kidney function.

S100-A8/A9 activated TLR4 in renal tubular cells to promote ischemia-reperfusion injury and fibrosis

Renal ischemia/reperfusion injury (IRI) is a significant clinical problem without effective therapy. Unbiased omics approaches may reveal key renal mediators to initiate IRI. S100-A8/A9 was identified as the most significantly upregulated gene and protein base on proteomic analysis and RNA sequencing during the early reperfusion stage. S100-A8/A9 levels were significantly increased 1 day after transplantation in patients with donation after brain death (DBD). S100-A8/A9 production was associated with CD11b⁺Ly6G⁺ CXCR2⁺ immunocytes infiltration. Administration of S100-A8/A9 blocker ABR238901 significantly alleviates renal tubular injury, inflammatory cell infiltration, and renal fibrosis after renal IRI. Mechanistically, S100-A8/A9 could promote renal tubular cell injury and profibrotic cytokine production via TLR4. In conclusion, our findings found that early activation of S100-A8/A9 in renal IRI and targeting S100-A8/A9 signaling alleviates tubular injury and inhibits inflammatory response and renal fibrosis, which may provide a novel target for the prevention and treatment of acute kidney injury.

Oxypurinol protects renal ischemia/reperfusion injury via heme oxygenase-1 induction

Renal ischemia/reperfusion (I/R) injury is a major cause of acute kidney injury (AKI) by increasing oxidative stress, inflammatory responses, and tubular cell death. Oxypurinol, an active metabolite of allopurinol, is a potent anti-inflammatory and antioxidant agent. To investigate the therapeutic potential and underlying mechanism of oxypurinol in ischemic AKI, C57BL/6 male mice were intraperitoneally injected with oxypurinol and subjected to renal I/R or sham surgery. We found that oxypurinol-treated mice had lower plasma creatinine and blood urea nitrogen levels and tubular damage (hematoxylin-and-eosin staining) compared to vehicle-treated mice after renal I/R injury. Furthermore, oxypurinol treatment reduced kidney inflammation (i.e., neutrophil infiltration and MIP-2 mRNA induction), oxidative stress (i.e., 4-HNE, heme oxygenase-1 [HO-1], 8-OHdG expression, and Catalase mRNA induction), and apoptosis (i.e., TUNEL or cleaved caspase-3-positive renal tubular cells), compared to vehicle-treated mice. Mechanistically, oxypurinol induced protein expressions of HO-1, which is a critical cytoprotective enzyme during ischemic AKI, and oxypurinol-mediated protection against ischemic AKI was completely eliminated by pretreatment with tin protoporphyrin IX, an HO-1 inhibitor. In conclusion, oxypurinol protects against renal I/R injury by reducing oxidative stress, inflammation, and apoptosis via HO-1 induction, suggesting its preventive potential in ischemic AKI.

Overexpression of miR-92a attenuates kidney ischemia-reperfusion injury and improves kidney preservation by inhibiting MEK4/JNK1-related autophagy

BACKGROUND

Kidney ischemia-reperfusion injury is inevitable in kidney transplantation, and is essential for primary graft dysfunction and delayed graft function. Our previous study has proved that miR-92a could ameliorate kidney ischemia-reperfusion injury, but the mechanism has not been studied.

METHODS

This study conducted further research on the role of miR-92a in kidney ischemia-reperfusion injury and organ preservation. In vivo, mice models of bilateral kidney ischemia (30 min), cold preservation after ischemia (cold preservation time of 6, 12, and 24 h), and ischemia-reperfusion (reperfusion time of 24, 48, and 72 h) were established. Before or after modeling, the model mice were injected with miR-92a-agomir through the caudal vein. In vitro, the hypoxia-reoxygenation of HK-2 cells was used to simulate ischemia-reperfusion injury.

RESULTS

Kidney ischemia and ischemia-reperfusion significantly damaged kidney function, decreased the expression of miR-92a, and increased apoptosis and autophagy in kidneys. miR-92a agomir tail vein injection significantly increased the expression of miR-92a in kidneys, improved kidney function, and alleviated kidney injury, and the intervention before modeling achieved a better effect than after. Moreover, miR-92a agomir significantly reduced the apoptosis and autophagy in HK-2 cells induced by hypoxia, hypoxia-reoxygenation, and rapamycin, while miR-92a antagomir had opposite effects. Furthermore, mitogen-activated protein kinase, c-Jun NH (2) terminal kinase, caspase 3, Beclin 1, and microtubule-associated protein 1 light chain 3B were inhibited by overexpression of miR-92a both in vivo and in vitro, which in turn reduced apoptosis and autophagy.

CONCLUSIONS

Our results prove that overexpression of miR-92a attenuated kidney ischemia-reperfusion injury and improved kidney preservation, and intervention before ischemia-reperfusion provides better protection than after.

SARS-CoV-2 viral protein ORF3A injures renal tubules by interacting with TRIM59 to induce STAT3 activation

Acute kidney injury occurs frequently in COVID-19 patients infected by the coronavirus SARS-CoV-2, and infection of kidney cells by this virus has been reported. However, little is known about the direct impact of the SARS-CoV-2 infection upon the renal tubular cells. We report that SARS-CoV-2 activated signal transducer and activator of transcription 3 (STAT3) signaling and caused cellular injury in the human renal tubular cell line. Mechanistically, the viral protein ORF3A of SARS-CoV-2 augmented both NF-κB and STAT3 signaling and increased the expression of kidney injury molecule 1. SARS-CoV-2 infection or expression of ORF3A alone elevated the protein level of tripartite motif-containing protein 59 (TRIM59), an E3 ubiquitin ligase, which interacts with both ORF3A and STAT3. The excessive TRIM59 in turn dissociated the phosphatase TCPTP from binding to STAT3 and hence inhibited the dephosphorylation of STAT3, leading to persistent STAT3 activation. Consistently, ORF3A induced renal injury in zebrafish and mice. In addition, expression of TRIM59 was elevated in the kidney autopsies of COVID-19 patients with acute kidney injury. Thus, the aberrant activation of STAT3 signaling by TRIM59 plays a significant role in the renal tubular cell injury caused by SARS-CoV-2, which suggests a potential targeted therapy for the renal complications of COVID-19.

Semaglutide in renal ischemia-reperfusion injury in mice

Ischemia and reperfusion injury (I/R) is a serious condition leading to organ failure, characterized by poor blood supply followed by rapid resuscitation of blood flow and reoxygenation. Renal failure caused by renal ischemia has high mortality and morbidity. This study aimed to explore the potential role of Semaglutide as a novel and effective therapeutic strategy for acute renal failure. Additionally, we aimed to assess the possible protective effect of Semaglutide on kidney I/R injury in mice through modulation of the inflammatory and oxidative pathways via phosphatidylinositol 3-kinase/adenosine triphosphate (PI3K/AKT) activation. We employed twenty-eight albino mice to induce the I/R injury model by clamping the renal artery for 30 min followed by a period of reperfusion for 2 hours. The control group was exposed to I/R injury, while the Semaglutide-treated group was pretreated with the drug 12 hours before induction of ischemia at a dose of 100 nmol/L/kg via the intraperitoneal route (i.p). In addition, the DMSO-treated group was subjected to similar conditions to the Semaglutide-treated group. At the end of the experiments, kidneys and blood samples were collected for investigation. Semaglutide could act as a protective agent against acute kidney injury by reducing inflammatory molecules such as tumor necrosis factor-alpha (TNF-α) and its cognate receptor, TNF-α R, interleukine-6 (IL-6). Furthermore, Semaglutide reduced F8 isoprostane levels, increased PI3K and AKT levels in renal tissues, and mitigated renal damage. Semaglutide had renoprotective effects via modulation of the inflammatory response and oxidative pathway by targeting the PI3K/AKT signaling pathway.

Radiotherapy Advances in Renal Disease-Focus on Renal Ischemic Preconditioning

Ionizing irradiation is widely applied as a fundamental therapeutic treatment in several diseases. Acute kidney injury (AKI) represents a global public health problem with major morbidity and mortality. Renal ischemia/reperfusion (I/R) is the main cause of AKI. I/R injury occurs when blood flow to the kidney is transiently interrupted and then restored. Such an ischemic insult significantly impairs renal function in the short and long terms. Renal ischemic preconditioning (IPC) corresponds to the maneuvers intended to prevent or attenuate the ischemic damage. In murine models, irradiation-induced preconditioning (IP) renders the renal parenchyma resistant to subsequent damage by activating defense pathways involved in oxidative stress, angiogenesis, and inflammation. Before envisioning translational applications in patients, safe irradiation modalities, including timing, dosage, and fractionation, need to be defined.

A molecular network-based pharmacological study on the protective effect of Panax notoginseng rhizomes against renal ischemia-reperfusion injury

Objective: We aimed to explore the protective effect of Panax notoginseng rhizomes (PNR) on renal ischemia and reperfusion injury (RIRI) and the underlying molecular network mechanism based on network pharmacology and combined systemic experimental validation. Methods: A bilateral RIRI model was established, and Cr, SCr, and BUN levels were detected. Then, the PNR was pretreated 1 week before the RIRI model was prepared. To determine the effects of the PNR in RIRI, histopathological damage and the effect of PNRs to the kidney was assessed, using TTC, HE, and TUNEL staining. Furthermore, the underlying network pharmacology mechanism was detected by screening drug-disease intersection targets from PPI protein interactions and GO and KEGG analysis, and the hub genes were screened for molecular docking based on the Degree value. Finally, the expression of hub genes in kidney tissues was verified by qPCR, and the protein expression of related genes was further detected by Western blot (WB). Results: PNR pretreatment could effectively increase Cr level, decrease SCr and BUN levels, reduce renal infarct areas and renal tubular cell injury areas, and inhibit renal cell apoptosis. By using network pharmacology combined with bioinformatics, we screened co-targets both Panax notoginseng (Sanchi) and RIRI, acquired ten hub genes, and successfully performed molecular docking. Of these, pretreatment with the PNR reduced the mRNA levels of IL6 and MMP9 at postoperative day 1 and TP53 at postoperative day 7, and the protein expression of MMP9 at postoperative day 1 in IRI rats. These results showed that the PNR could decrease kidney pathological injury in IRI rats and inhibit apoptotic reaction and cell inflammation so as to improve renal injury effectively, and the core network mechanism is involved in the inhibition of MMP9, TP53, and IL-6. Conclusion: The PNR has a marked protective effect for RIRI, and the underlying mechanism is involved in inhibiting the expression of MMP9, TP53, and IL-6. This striking discovery not only provides fruitful evidence for the protective effect of the PNR in RIRI rats but also provides a novel mechanic explanation.

Contribution to the Preclinical Safety Assessment of Lannea velutina and Sorindeia juglandifolia Leaves

Dried leaves of Lannea velutina A. Rich. and Sorindeia juglandifolia (A. Rich.) Planch. ex Oliv. (family Anacardiaceae) are used in African traditional medicine. Although these medicinal plants have widespread use in the treatment of inflammatory diseases, there is no scientific data concerning their preclinical or clinical safety. This work aimed to investigate the phytochemical properties of the leaves of both species using HPLC-UV/DAD, as well as the in vivo oral repeated-dose toxicity of 70% hydroethanolic leaf extract of S. juglandifolia and the in vitro genotoxicity of 70% hydroethanolic leaf extracts of L. velutina and S. juglandifolia. Clinical signs of toxicity, body weight variations, and changes in food consumption, mortality, and blood biochemical parameters were monitored. Genotoxicity was assessed using the bacterial reverse mutation assay (Ames test) with and without metabolic activation, according to OECD guidelines. The obtained results showed the presence of gallic acid and anacardic acid as the main marker constituents in both species. No significant changes in general body weight or food intake were observed; small significant changes with no critical relevance were observed in the blood biochemistry of animals treated with S. juglandifolia hydroethanolic extract (50, 400, and 1000 mg/kg body weight) compared to those in the control group. No genotoxicity was observed in the bacterial reverse mutation assay with S. juglandifolia and L. velutina extracts (up to 5 mg/plate). The safety data obtained in vivo and lack of genotoxic potential in vitro points to the safe medicinal use of S. juglandifolia and L. velutina extracts.

Diagnosis of Ischemic Renal Failure Using Surface-Enhanced Raman Spectroscopy and a Machine Learning Algorithm

To diagnose renal function using a biochip capable of detecting SERS and to assess Raman measurements taken from a bilateral renal ischemia model and the feasibility of early diagnosis was done. After generating a bilateral renal ischemia rat model, blood and urine were collected. After confirming the presence of renal injury and function, liquid drops were placed onto a Raman chip whose surface had been enhanced with Au-ZnO nanorods. SERS biomarkers that diffused into the nanogaps were selectively amplified. Raman signals varied based on the severity of the renal function, and these differences were confirmed statistically. These results confirm that renal ischemia leads to renal dysfunction and that surface-enhanced Raman spectroscopy and a machine learning algorithm can be used to track signals in the urine from the release of SERS biomarkers.

Anesthesia and analgesia for common research models of adult mice

Anesthesia and analgesia are major components of many interventional studies on laboratory animals. However, various studies have shown improper reporting or use of anesthetics/analgesics in research proposals and published articles. In many cases, it seems "anesthesia" and "analgesia" are used interchangeably, while they are referring to two different concepts. Not only this is an unethical practice, but also it may be one of the reasons for the proven suboptimal quality of many animal researches. This is a widespread problem among investigations on various species of animals. However, it could be imagined that it may be more prevalent for the most common species of laboratory animals, such as the laboratory mice. In this review, proper anesthetic/analgesic methods for routine procedures on laboratory mice are discussed. We considered the available literature and critically reviewed their anesthetic/analgesic methods. Detailed dosing and pharmacological information for the relevant drugs are provided and some of the drugs' side effects are discussed. This paper provides the necessary data for an informed choice of anesthetic/analgesic methods in some routine procedures on laboratory mice.

HDAC6 Inhibition Alleviates Ischemia- and Cisplatin-Induced Acute Kidney Injury by Promoting Autophagy

Histone deacetylase (HDAC) 6 exists exclusively in cytoplasm and deacetylates cytoplasmic proteins such as α-tubulin. HDAC6 dysfunction is associated with several pathological conditions in renal disorders, including UUO-induced fibrotic kidneys and rhabdomyolysis-induced nephropathy. However, the role of HDAC6 in ischemic acute kidney injury (AKI) and the mechanism by which HDAC6 inhibition protects tubular cells after AKI remain unclear. In the present study, we observed that HDAC6 was markedly activated in kidneys subjected to ischemia- and cisplatin (cis)-induced AKI treatment. Pharmacological inhibition of HDAC6 alleviated renal impairment and renal tubular damage after ischemia and cisplatin treatment. HDAC6 dysfunction was associated with decreased acetylation of α-tubulin at the residue of lysine 40 and autophagy. HDAC6 inhibition preserved acetyl-α-tubulin-enhanced autophagy flux in AKI and cultured tubular cells. Genetic ablation of the renal tubular (RT) Atg7 gene or pharmacological inhibition of autophagy suppressed the protective effects of HDAC6. Taken together, our study indicates that HDAC6 contributes to ischemia- and cisplatin-induced AKI by inhibiting autophagy and the acetylation of α-tubulin. These results suggest that HDAC6 could be a potential target for ischemic and nephrotoxic AKI.

Quiescence-inducing neurons-induced hypometabolism ameliorates acute kidney injury in a mouse model mimicking cardiovascular surgery requiring circulatory arrest

Objectives

Acute kidney injury is a serious complication after cardiovascular surgery requiring circulatory arrest. It is reported that mice can be induced into a hibernation-like hypometabolic state by stimulating a specific neuron located at the hypothalamus (quiescence-inducing neurons-induced hypometabolism [QIH]). Here, we investigated the efficacy of QIH for the amelioration of acute kidney injury in an experimental circulatory arrest using a transgenic mouse model.

Methods

We genetically prepared mice in which QIH can be conditionally induced (QIH-ready mice). Mice were divided into 4 groups (n = 6 for each): QIH-ready normothermia (QN), QIH-ready hypothermia (QH), control normothermia (CN), and control hypothermia (CH). After induction of QIH, left thoracotomy and descending aorta crossclamping were conducted. After reperfusion, we collected kidneys and evaluated histologic changes and serum biochemical markers, specifically neutrophil gelatinase-associated lipocalin and cystatin C, indicating early kidney injury.

Results

Normothermia showed higher tubular injury scores than those in hypothermia (QN vs QH [P = .0021] and CN vs CH [P < .001]). QN exhibited lower neutrophil gelatinase-associated lipocalin and cystatin C levels than those in CN (neutrophil gelatinase-associated lipocalin: CN vs QN: 1.51 ± 0.71 vs 0.82 ± 0.32; P = .0414 and cystatin C: 1.48 ± 0.39 vs 0.71 ± 0.26; P = .0015). There was no significant difference between QN and QH.

Conclusions

QIH partly ameliorated acute kidney injury in a mouse ischemia model even in normothermia. QIH might be a promising approach to achieving sufficient kidney protection without hypothermic circulatory arrest in the future.

Effects of contralateral nephrectomy timing and ischemic conditions on kidney fibrosis after unilateral kidney ischemia-reperfusion injury

Acute kidney injury (AKI) is an important cause of chronic kidney disease (CKD), but the underlying mechanisms are unclear. Animal models are tools for studying the AKI-CKD progression. Kidney ischemia-reperfusion injury (IRI) models, especially the unilateral IRI (uIRI) model with delayed contralateral kidney resection, are commonly used to induce fibrotic progression to CKD after AKI. However, in previous studies, we found that details of the operation had a significant impact on the long-term outcomes of the kidney in this uIRI model. In this study, we investigated the effects of resection timing of the contralateral intact kidney, core body temperatures during ischemia, and time length of kidney ischemia on kidney function, histological injury and kidney fibrosis after AKI, using a mouse uIRI model with delayed contralateral nephrectomy. The results showed that all these parameters significantly affected the AKI-CKD transition. The post-AKI fibrosis worsened and the survival rate declined with a longer interval between contralateral nephrectomy and uIRI, higher ischemic body temperature, or longer ischemic duration when the other two variables were fixed. In conclusion, in the uIRI model with delayed contralateral nephrectomy, kidney fibrosis after AKI is influenced by many factors. Strictly controlling the experimental conditions is very important for the stability and consistency of the model.

No safe renal warm ischemia time-The molecular network characteristics and pathological features of mild to severe ischemia reperfusion kidney injury

Ischemic acute kidney injury (AKI) has always been a hot and difficult research topic in the field of renal diseases. This study aims to illustrate the safe warm ischemia time of kidney and the molecular network characteristics and pathological features of mild to severe ischemia reperfusion kidney injury. We established varying degrees of renal injury due to different ischemia time (0 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min, and 30 min) on unilateral (left kidney) ischemia-reperfusion injury and contralateral (right kidney) resection (uIRIx) mouse model. Mice were sacrificed 24 h after uIRIx, blood samples were harvested to detect serum creatinine (Scr), and kidney tissue samples were harvested to perform Periodic Acid-Schiff (PAS) staining and RNA-Seq. Differentially expressed genes (DEGs) were identificated, time-dependent gene expression patterns and functional enrichment analysis were further performed. Finally, qPCR was performed to validated RNA-Seq results. Our results indicated that there was no absolute safe renal warm ischemia time, and every minute of ischemia increases kidney damage. Warm ischemia 26min or above in mice makes severe kidney injury, renal pathology and SCr were both significantly changed. Warm ischemia between 18 and 26 min makes mild kidney injury, with changes in pathology and renal molecular expression, while SCr did not change. No obvious pathological changes but significant differences in molecular expression were found less than 16min warm ischemia. There are two key time intervals in the process of renal ischemia injury, 0 min-16 min (short-term) and 26 min-28 min (long-term). Gene expression of immune-related pathways were most significantly down-regulated in short-term ischemia, while metabolism-related pathways were the mainly enriched pathway in long-term ischemia. Taken together, this study provides novel insights into safe renal artery occlusion time in partial nephrectomy, and is of great value for elucidating molecular network characteristics and pathological features of mild to severe ischemia reperfusion kidney injury, and key genes related to metabolism and immune found in this study also provide potential diagnostic and therapeutic biomarkers for AKI.

The Sphingosine Kinase 2 Inhibitor Opaganib Protects Against Acute Kidney Injury in Mice

Introduction

Acute kidney injury (AKI) is a common multifactorial adverse effect of surgery, circulatory obstruction, sepsis or drug/toxin exposure that often results in morbidity and mortality. Sphingolipid metabolism is a critical regulator of cell survival and pathologic inflammation processes involved in AKI. Opaganib (also known as ABC294640) is a first-in-class experimental drug targeting sphingolipid metabolism that reduces the production and activity of inflammatory cytokines and, therefore, may be effective to prevent and treat AKI.

Methods

Murine models of AKI were used to assess the in vivo efficacy of opaganib including ischemia-reperfusion (IR) injury induced by either transient bilateral occlusion of renal blood flow (a moderate model) or nephrectomy followed immediately by occlusion of the contralateral kidney (a severe model) and lipopolysaccharide (LPS)-induced sepsis. Biochemical and histologic assays were used to quantify the effects of oral opaganib treatment on renal damage in these models.

Results

Opaganib suppressed the elevations of creatinine and blood urea nitrogen (BUN), as well as granulocyte infiltration into the kidneys, of mice that experienced moderate IR from transient bilateral ligation. Opaganib also markedly decreased these parameters and completely prevented mortality in the severe renal IR model. Additionally, opaganib blunted the elevations of BUN, creatinine and inflammatory cytokines following exposure to LPS.

Conclusion

The data support the hypotheses that sphingolipid metabolism is a key mediator of renal inflammatory damage following IR injury and sepsis, and that this can be suppressed by opaganib. Because opaganib has already undergone clinical testing in other diseases (cancer and Covid-19), the present studies support conducting clinical trials with this drug with surgical or septic patients at risk for AKI.

A network pharmacology-based study on the mechanism of astragaloside IV alleviating renal fibrosis through the AKT1/GSK-3β pathway

ETHNOPHARMACOLOGICAL REVELVANCE

Astragaloside IV, a glycoside derived from Astragalus membranaceus, has anti-renal fibrosis effects. However, its mechanism of action has not yet been fully elucidated.

AIM OF THE STUDY

The purpose of this study was to investigate the anti-fibrotic effect of AS-IV and to clarify its underlying mechanism.

MATERIALS AND METHODS

The network pharmacology method, molecular docking and surface plasmon resonance (SPR) was used to identify potential targets and pathways of AS-IV. A unilateral ischemia-reperfusion injury (UIRI) animal model, as well as TGF-β1-induced rat renal tubular epithelial cells (NRK-52E) and renal fibroblasts (NRK-49F) were used to investigate and validate the anti-fibrotic activity and pharmacological mechanism of AS-IV. Network pharmacology was performed to construct a drug-target-pathway network. The anti-fibrosis effect of AS-IV was determined using hematoxylin-eosin (H&E) and MASSON staining, as well as immunostaining methods. qRT-PCR and western blotting were used to elucidate and validate the mechanism of AS-IV.

RESULTS

Network pharmacology revealed that the PI3K/AKT pathway is an important pathway in AS-IV. AS-IV inhibited the expression of α-SMA, collagen I, and fibronectin in NRK-52E, NRK-49F, and UIRI rats, and reduced serum creatinine and blood urea nitrogen levels in UIRI rats. AS-IV inhibited AKT phosphorylation, blocked GSK-3β phosphorylation, and restored GSK-3β activity, which contributed to the degradation of β-catenin, thereby preventing epithelial-mesenchymal transition (EMT).

CONCLUSION

Astragaloside IV alleviated renal fibrosis through the AKT1/GSK-3β pathway. In addition, our findings indicate that the network pharmacology method is a powerful tool for exploring the pharmacological mechanisms of drugs.

An Albumin-Enriched Nanocomplex Achieves Systemic Delivery of Clopidogrel Bisulfate to Ameliorate Renal Ischemia Reperfusion Injury in Rats

Herein, an albumin-enriched nanocomplex was developed for the solubilization and intravascular administration of clopidogrel bisulfate (CLP). In particular, CLP nanoparticles (HS-CLP-NPs) were synthesized via an improved nab-technology method using Solutol HS-15, and bovine serum albumin (BSA) was further enriched on the nanoparticle surface forming a protein corona (BH-CLP-NPs). BH-CLP-NPs displayed an average size of 163.4 ± 10.5 nm, a zeta potential of 1.85 ± 0.03 mV, an encapsulation efficiency of 99.9%, and a drug loading capacity of 32.9%. The cumulative release of CLP from BH-CLP-NPs reached about 60% within 168 h. The pharmacokinetic study on the CLP metabolite indicated that the BSA-enriched nanoparticle showed greater in vivo exposure. Pharmacodynamic studies in the renal ischemia/reperfusion injury rat model further demonstrated the renal protective effect of systemically administered BH-CLP-NPs against acute kidney injury with significantly downregulated blood urea nitrogen and creatinine levels. Overall, the albumin-enriched nanocomplexes offer a neat and efficient strategy for the development of poorly water-soluble drugs to achieve intravascular administration.

The VEGF Inhibitor Soluble Fms-like Tyrosine Kinase 1 Does Not Promote AKI-to-CKD Transition

(1) Background: Soluble Fms-like tyrosine kinase 1 (sFLT1) is an endogenous VEGF inhibitor. sFLT1 has been described as an anti-inflammatory treatment for diabetic nephropathy and heart fibrosis. However, sFLT1 has also been related to peritubular capillary (PTC) loss, which promotes fibrogenesis. Here, we studied whether transfection with sFlt1 aggravates experimental AKI-to-CKD transition and whether sFLT1 is increased in human kidney fibrosis. (2) Methods: Mice were transfected via electroporation with sFlt1. After confirming transfection efficacy, mice underwent unilateral ischemia/reperfusion injury (IRI) and were sacrificed 28 days later. Kidney histology and RNA were analyzed to study renal fibrosis, PTC damage and inflammation. Renal sFLT1 mRNA expression was measured in CKD biopsies and control kidney tissue. (3) Results: sFlt1 transfection did not aggravate renal fibrosis, PTC loss or macrophage recruitment in IRI mice. In contrast, higher transfection efficiency was correlated with reduced expression of pro-fibrotic and pro-inflammatory markers. In the human samples, sFLT1 mRNA levels were similar in CKD and control kidneys and were not correlated with interstitial fibrosis or PTC loss. (4) Conclusion: As we previously found that sFLT1 has therapeutic potential in diabetic nephropathy, our findings indicate that sFLT1 can be administered at a dose that is therapeutically effective in reducing inflammation, without promoting maladaptive kidney damage.

Immune-mediated tubule atrophy promotes acute kidney injury to chronic kidney disease transition

Incomplete repair after acute kidney injury can lead to development of chronic kidney disease. To define the mechanism of this response, we compared mice subjected to identical unilateral ischemia-reperfusion kidney injury with either contralateral nephrectomy (where tubule repair predominates) or contralateral kidney intact (where tubule atrophy predominates). By day 14, the kidneys undergoing atrophy had more macrophages with higher expression of chemokines, correlating with a second wave of proinflammatory neutrophil and T cell recruitment accompanied by increased expression of tubular injury genes and a decreased proportion of differentiated tubules. Depletion of neutrophils and T cells after day 5 reduced tubular cell loss and associated kidney atrophy. In kidney biopsies from patients with acute kidney injury, T cell and neutrophil numbers negatively correlated with recovery of estimated glomerular filtration rate. Together, our findings demonstrate that macrophage persistence after injury promotes a T cell- and neutrophil-mediated proinflammatory milieu and progressive tubule damage.

Transcriptional progressive patterns from mild to severe renal ischemia/reperfusion-induced kidney injury in mice

The renal ischemia/reperfusion (I/R)-induced acute kidney injury incidence after nephron-sparing surgery for localized renal tumors is 20%, but the biological determinant process of postoperative acute kidney injury remains unclear. Using Gene Expression Omnibus database (GSE192883) and several bioinformatics analyses (discrete time points analysis, gene set enrichment analysis, dynamic network biomarker analysis, etc), combined with the establishment of the I/R model for verification, we identified three progressive patterns involving five core pathways confirmed using gene set enrichment analysis and six key genes (S100a10, Pcna, Abat, Kmo, Acadm, and Adhfe1) verified using quantitative polymerase chain reaction The dynamic network biomarker (DNB) subnetwork composite index value is the highest in the 22-min ischemia group, suggesting the transcriptome expression level fluctuated sharply in this group, which means 22-min ischemia is an critical warning point. This study illustrates the core molecular progressive patterns from mild to severe I/R kidney injury, laying the foundation for precautionary biomarkers and molecular intervention targets for exploration. In addition, the safe renal artery blocking time of nephron-sparing surgery that we currently accept may not be safe anymore.

Exosomal lncRNA TUG1 derived from human urine-derived stem cells attenuates renal ischemia/reperfusion injury by interacting with SRSF1 to regulate ASCL4-mediated ferroptosis

Background

Human urine-derived stem cells (USCs)-derived exosomes (USC-Exo) could improve kidney ischemia/reperfusion injury (IRI), while the underlying mechanisms of this protective effect remain unclear.

Methods

Human USCs and USC-Exo were isolated and verified by morphology and specific biomarkers. The effects of USC-Exo on ferroptosis and kidney injury were detected in the IRI-induced acute kidney injury (AKI) model in C57BL/6 mice. The effects of USC-Exo on ferroptosis and lncRNA taurine-upregulated gene 1 (TUG1) were detected in hypoxia/reoxygenation (H/R)-treated human proximal tubular epithelial cells (HK-2). The interaction of SRSF1 and TUG1, ACSL4 was checked via RNA pull-down/RIP and RNA stability assays. The effects of LncRNA TUG1 on SRSF1/ACSL4-mediated ferroptosis were verified in H/R-treated HK-2 cells and the IRI-induced AKI mouse models.

Results

USC-Exo treatment improved kidney injury and ameliorated ferroptosis in IRI-induced AKI mouse models. USC-Exo were rich in lncRNA TUG1, which suppressed ferroptosis in HK-2 cells exposed to H/R. Mechanistically, lncRNA TUG1 regulates the stability of ACSL4 mRNA by interacting with RNA-binding protein SRSF1. In addition, SRSF1 upregulation or ACSL4 downregulation partially reversed the protective effect of lncRNA TUG1 on ferroptosis in H/R-treated HK-2 cells. Further, ACSL4 upregulation partially reversed TUG1’s repression on kidney injury and ferroptosis in IRI-induced AKI mice.

Conclusion

Collectively, lncRNA TUG1 carried by USC-Exo regulated ASCL4-mediated ferroptosis by interacting with SRSF1 and then protected IRI-induced AKI. Potentially, USC-Exo rich in lncRNA TUG1 can serve as a promising therapeutic method for IRI-AKI.

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

ETHNOPHARMACOLOGICAL RELEVANCE

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

AIM OF THE STUDY

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Manganese Porphyrin Promotes Post Cardiac Arrest Recovery in Mice and Rats

Introduction Cardiac arrest (CA) and resuscitation induces global cerebral ischemia and reperfusion, causing neurologic deficits or death. Manganese porphyrins, superoxide dismutase mimics, are reportedly able to effectively reduce ischemic injury in brain, kidney, and other tissues. This study evaluates the efficacy of a third generation lipophilic Mn porphyrin, MnTnBuOE-2-PyP5+, Mn(III) ortho meso-tetrakis (N-n-butoxyethylpyridinium-2-yl)porphyrin (MnBuOE, BMX-001), in both mouse and rat models of CA. Methods Forty-eight animals were subjected to 8 min of CA and resuscitated subsequently by chest compression and epinephrine infusion. Vehicle or MnBuOE was given immediately after resuscitation followed by daily subcutaneous injections. Body weight, spontaneous activity, neurologic deficits, rotarod performance, and neuronal death were assessed. Kidney tubular injury was assessed in CA mice. Data were collected by the investigators who were blinded to the treatment groups. Results Vehicle mice had a mortality of 20%, which was reduced by 50% by MnBuOE. All CA mice had body weight loss, spontaneous activity decline, neurologic deficits, and decreased rotarod performance that were significantly improved at three days post MnBuOE daily treatment. MnBuOE treatment reduced cortical neuronal death and kidney tubular injury in mice (p < 0.05) but not hippocampus neuronal death (23% MnBuOE vs. 34% vehicle group, p = 0.49). In rats, they had a better body-weight recovery and increased rotarod latency after MnBuOE treatment when compared to vehicle group (p < 0.01 vs. vehicle). MnBuOE-treated rats had a low percentage of hippocampus neuronal death (39% MnBuOE vs. 49% vehicle group, p = 0.21) and less tubular injury (p < 0.05) relative to vehicle group. Conclusions We demonstrated the ability of MnBuOE to improve post-CA survival, as well as functional outcomes in both mice and rats, which jointly account for the improvement not only of brain function but also of the overall wellbeing of the animals. While MnBuOE bears therapeutic potential for treating CA patients, the females and the animals with comorbidities must be further evaluated before advancing toward clinical trials.

Arginase-1 Is Required for Macrophage-Mediated Renal Tubule Regeneration

BACKGROUND

After kidney injury, macrophages transition from initial proinflammatory activation to a proreparative phenotype characterized by expression of arginase-1 (Arg1), mannose receptor 1 (Mrc1), and macrophage scavenger receptor 1 (Msr1). The mechanism by which these alternatively activated macrophages promote repair is unknown.

METHODS

We characterized the macrophage and renal responses after ischemia-reperfusion injury with contralateral nephrectomy in LysM-Cre;Arg1^fl/fl mice and littermate controls and used in vitro coculture of macrophages and tubular cells to determine how macrophage-expressed arginase-1 promotes kidney repair.

RESULTS

After ischemia-reperfusion injury with contralateral nephrectomy, Arg1-expressing macrophages were almost exclusively located in the outer stripe of the medulla adjacent to injured S3 tubule segments containing luminal debris or casts. Macrophage Arg1 expression was reduced by more than 90% in injured LysM-Cre;Arg1^fl/fl mice, resulting in decreased mouse survival, decreased renal tubular cell proliferation and decreased renal repair compared with littermate controls. In vitro studies demonstrate that tubular cells exposed apically to dead cell debris secrete high levels of GM-CSF and induce reparative macrophage activation, with those macrophages in turn secreting Arg1-dependent factor(s) that directly stimulate tubular cell proliferation.

CONCLUSIONS

GM-CSF-induced, proreparative macrophages express arginase-1, which is required for the S3 tubular cell proliferative response that promotes renal repair after ischemia-reperfusion injury.

Hidden in Plain Sight: Does Medullary Red Blood Cell Congestion Provide the Explanation for Ischemic Acute Kidney Injury?

Acute kidney injury (AKI) represents a sudden reduction in renal function and is a major clinical problem with a high mortality rate. Despite decades of research, there are currently no direct therapies for AKI. The failure of therapeutic approaches identified in rodents to translate to human beings has led to questions regarding the appropriateness of these models. Our recent data indicate that there are two distinct processes driving tubular injury in the commonly used rat model of warm bilateral renal ischemia reperfusion injury, which often is used to mimic ischemic AKI. One results from the period of warm ischemia, manifesting as sublethal injury and coagulative necrosis of the proximal tubules in the renal cortex. This is the predominate type of injury observed 24 hours after reperfusion and the most well studied. The other results from red blood cell congestion of the outer medullary vasculature. This type of injury manifests as cell sloughing, along with the later formation of heme casts that fill distal nephron segments. Cell sloughing from congestion is most prominent in the early hours after reperfusion and often is masked by regeneration of the tubular epithelium by 24 hours postischemia. In this review, we argue that injury from outer medullary red blood cell congestion reflects the pathology observed in human kidneys and likely is representative of injury in most cases of ischemic AKI after shock. Greater focus on this congestive injury is likely to lead to improved translation in AKI.

A Reproducible Mouse Model of Moderate CKD With Early Manifestations of Osteoblastic Transition of Cardiovascular System

Chronic kidney disease (CKD) is a significant public health challenge with a substantial associated risk of mortality, morbidity, and health care expenditure. Culprits that lead to development and progression of CKD are multifaceted and heterogenous in nature. This notion underscores the need for diversification of animal models to investigate its pathophysiology, related complications, and to subsequently enable discovery of novel therapeutics. Importantly, animal models that could recapitulate complications of CKD in both genders are desperately needed. Cardiovascular disease is the most common cause of death in CKD patients that may be due in part to high prevalence of vascular calcification (VC). Using DBA/2 mice that are susceptible to development of VC, we sought to investigate the feasibility and reproducibility of a unilateral ischemia-reperfusion model followed by contralateral nephrectomy (UIRI/Nx) to induce CKD and its related complications in female and male mice. Our results demonstrate that irrespective of gender, mice faithfully displayed complications of moderate CKD following UIRI/Nx as evidenced by significant rise in serum creatinine, albuminuria, higher degree of collagen deposition, elevated expression of classic fibrotic markers, higher circulating levels of FGF-23, PTH and hepcidin. Moreover, we corroborate the osteoblastic transition of aortic smooth muscle cells and cardiomyocytes based on higher levels of osteoblastic markers namely, Cbfa-1, osteopontin, osteocalcin, and osterix. Our data confirms a viable, and consistent model of moderate CKD and its associated complications in both male and female mice. Furthermore, early evidence of osteoblastic transition of cardiovascular system in this model confirms its suitability for studying and implementing potential preventive and/or therapeutic approaches that are urgently needed in this field.

Single Cell RNA Sequencing Identifies a Unique Inflammatory Macrophage Subset as a Druggable Target for Alleviating Acute Kidney Injury

Acute kidney injury (AKI) is a complex clinical disorder associated with poor outcomes. Targeted regulation of the degree of inflammation has been a potential strategy for AKI management. Macrophages are the main effector cells of kidney inflammation. However, macrophage heterogeneity in ischemia reperfusion injury induced AKI (IRI-AKI) remains unclear. Using single-cell RNA sequencing of the mononuclear phagocytic system in the murine IRI model, the authors demonstrate the complementary roles of kidney resident macrophages (KRMs) and monocyte-derived infiltrated macrophages (IMs) in modulating tissue inflammation and promoting tissue repair. A unique population of S100a9^hi Ly6c^hi IMs is identified as an early responder to AKI, mediating the initiation and amplification of kidney inflammation. Kidney infiltration of S100A8/A9⁺ macrophages and the relevance of renal S100A8/A9 to tissue injury is confirmed in human AKI. Targeting the S100a8/a9 signaling with small-molecule inhibitors exhibits renal protective effects represented by improved renal function and reduced mortality in bilateral IRI model, and decreased inflammatory response, ameliorated kidney injury, and improved long-term outcome with decreased renal fibrosis in the unilateral IRI model. The findings support S100A8/A9 blockade as a feasible and clinically relevant therapy potentially waiting for translation in human AKI.

Murine models of renal ischemia reperfusion injury: An opportunity for refinement using noninvasive monitoring methods

BACKGROUND

Renal ischemia reperfusion injury (R-IRI) can cause acute kidney injury (AKI) and chronic kidney disease (CKD), resulting in significant morbidity and mortality. To understand the underlying mechanisms, reproducible small-animal models of AKI and CKD are needed. We describe how innovative technologies for measuring kidney function noninvasively in small rodents allow successful refinement of the R-IRI models, and offer the unique opportunity to monitor longitudinally in individual animals the transition from AKI to CKD.

METHODS

Male BALB/c mice underwent bilateral renal pedicle clamping (AKI) or unilateral renal pedicle clamping with delayed contralateral nephrectomy (CKD) under isoflurane anesthetic. Transdermal GFR monitoring and multispectral optoacoustic tomography (MSOT) in combination with statistical analysis were used to identify and standardize variables within these models.

RESULTS

Pre-clamping anesthetic time was one of the most important predictors of AKI severity after R-IRI. Standardizing pre-clamping time resulted in a more predictably severe AKI model. In the CKD model, MSOT demonstrated initial improvement in renal function, followed by significant progressive reduction in function between weeks 2 and 4. Performing contralateral nephrectomy on day 14 enabled the development of CKD with minimal mortality.

CONCLUSIONS

Noninvasive monitoring of global and individual renal function after R-IRI is feasible and reproducible. These techniques can facilitate refinement of kidney injury models and enable the degree of injury seen in preclinical models to be translated to those seen in the clinical setting. Thus, future therapies can be tested in a clinically relevant, noninvasive manner.

Experimental models of acute kidney injury for translational research

Preclinical models of human disease provide powerful tools for therapeutic discovery but have limitations. This problem is especially apparent in the field of acute kidney injury (AKI), in which clinical trial failures have been attributed to inaccurate modelling performed largely in rodents. Multidisciplinary efforts such as the Kidney Precision Medicine Project are now starting to identify molecular subtypes of human AKI. In addition, over the past decade, there have been developments in human pluripotent stem cell-derived kidney organoids as well as zebrafish, rodent and large animal models of AKI. These organoid and AKI models are being deployed at different stages of preclinical therapeutic development. However, the traditionally siloed, preclinical investigator-driven approaches that have been used to evaluate AKI therapeutics to date rarely account for the limitations of the model systems used and have given rise to false expectations of clinical efficacy in patients with different AKI pathophysiologies. To address this problem, there is a need to develop more flexible and integrated approaches, involving teams of investigators with expertise in a range of different model systems, working closely with clinical investigators, to develop robust preclinical evidence to support more focused interventions in patients with AKI.

Leptin relieves ischemia/reperfusion induced acute kidney injury through inhibiting apoptosis and autophagy

OBJECTIVES

Acute kidney injury (AKI) can be caused by ischemia/reperfusion (I/R), nephrotoxin, and sepsis, with poor prognosis and high mortality. Leptin is a protein molecule that regulates the body's energy metabolism and reproductive activities via binding to its specific receptor. Leptin can inhibit cardiomyocyte apoptosis caused by I/R, but its effect on I/R kidney injury and the underlying mechanisms are still unclear. This study aims to investigate the effect and mechanisms of leptin on renal function, renal histopathology, apoptosis, and autophagy during acute I/R kidney injury.

METHODS

Healthy adult male mice were randomly divided into 4 groups: a sham+wild-type mice (ob/+) group, a sham+leptin gene-deficient mice (ob/ob) group, an I/R+ob/+ group, and an I/R+ob/ob group (n=8 per group). For sham operation, a longitudinal incision was made on the back of the mice to expose and separate the bilateral kidneys and renal arteries, and no subsequent treatment was performed. I/R treatment was ischemia for 30 min and reperfusion for 48 h. The levels of BUN and SCr were detected to evaluate renal function; HE staining was used to observe the pathological changes of renal tissue; TUNEL staining was used to observe cell apoptosis, and apoptosis-positive cells were counted; Western blotting was used to detect levels of apoptosis-related proteins (caspase 3, caspase 9), autophagy-related proteins [mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), LC3 I, LC3 II], mTOR-dependent signaling pathway proteins [phosphate and tension homology (PTEN), adenosine monophosphate-activated protein kinase (AMPK), protein kinase B (AKT), extracellular regulated protein kinase (ERK), phosphorylated PTEN (p-PTEN), phosphorylated AMPK (p-AMPK), phosphorylated AKT (p-AKT), phosphorylated ERK (p-ERK)].

RESULTS

There was no significant difference in the levels of BUN and SCr between the sham+ob/+ group and the sham+ob/ob group (both P>0.05). The levels of BUN and SCr in the I/R+ob/+ group were significantly higher than those in the sham+ob/+ group (both P<0.05). Compared with the mice in the sham+ob/ob group or the I/R+ob/+ group, the levels of BUN and SCr in the I/R+ob/ob group were significantly increased (all P<0.05). There was no obvious damage to the renal tubules in the sham+ob/+ group and the sham+ob/ob group. Compared with sham+ob/+ group and sham+ob/ob group, both the I/R+ob/+ group and the I/R+ob/ob group had cell damage such as brush border shedding, vacuolar degeneration, and cast formation. Compared with the I/R+ob/+ group, the renal tubules of the mice in the I/R+ob/ob group were more severely damaged. The pathological score of renal tubular injury showed that the renal tubular injury was the most serious in the I/R+ob/ob group (P<0.05). Compared with the sham+ob/+ group, the protein levels of caspase 3, caspase 9, PTEN, and LC3 II were significantly up-regulated, the ratio of LC3 II to LC3 I was significantly increased, and the protein levels of p-mTOR, p-PTEN, p-AMPK, p-AKT, and p-ERK were significantly down-regulated in the I/R+ob/+ group (all P<0.05). Compared with the sham+ob/ob group, the protein levels of caspase 3, caspase 9, PTEN, and LC3 II were significantly up-regulated, and the ratio of LC3 II to LC3 I was significantly increased, while the protein levels of p-mTOR, p-PTEN, p-AMPK, p-AKT, and p-ERK were significantly down-regulated in the I/R+ob/ob group (all P<0.05). Compared with the I/R+ob/+ group, the levels of p-mTOR, p-PTEN, p-AMPK, p-AKT were more significantly down-regulated, while the levels of caspase 3, caspase 9, PTEN, and LC3 II were more significantly up-regulated, and the ratio of LC3 II to LC3 I was more significantly increase in the I/R+ob/ob group (all P<0.05).

CONCLUSIONS

Renal function and tubular damage, and elevated levels of apoptosis and autophagy are observed in mice kidneys after acute I/R. Leptin might relieve I/R induced AKI by inhibiting apoptosis and autophagy that through a complex network of interactions between mTOR-dependent signaling pathways.

Inhibition of HDAC3 protects against kidney cold storage/transplantation injury and allograft dysfunction

Cold storage/rewarming is an inevitable process for kidney transplantation from deceased donors, which correlates closely with renal ischemia-reperfusion injury (IRI) and the occurrence of delayed graft function. Histone deacetylases (HDAC) are important epigenetic regulators, but their involvement in cold storage/rewarming injury in kidney transplantation is unclear. In the present study, we showed a dynamic change of HDAC3 in a mouse model of kidney cold storage followed by transplantation. We then demonstrated that the selective HDAC3 inhibitor RGFP966 could reduce acute tubular injury and cell death after prolonged cold storage with transplantation. RGFP966 also improved renal function, kidney repair and tubular integrity when the transplanted kidney became the sole life-supporting graft in the recipient mouse. In vitro, cold storage of proximal tubular cells followed by rewarming induced remarkable cell death, which was suppressed by RGFP966 or knockdown of HDAC3 with shRNA. Inhibition of HDAC3 decreased the mitochondrial pathway of apoptosis and preserved mitochondrial membrane potential. Collectively, HDAC3 plays a pathogenic role in cold storage/rewarming injury in kidney transplantation, and its inhibition may be a therapeutic option.

Novel pharmacological effects of lecithinized superoxide dismutase on ischemia/reperfusion injury in the kidneys of mice

Renal ischemia/reperfusion (I/R) injury is a major clinical problem because it can cause acute kidney injury (AKI) or lead to the transition from AKI to chronic kidney disease (CKD). Oxidative stress, which involves the production of reactive oxygen species (ROS), plays an important role in the development and exacerbation of I/R-induced kidney injury. However, we have previously reported that lecithinized superoxide dismutase (PC-SOD), a SOD derivative with high tissue affinity and high stability in plasma, has beneficial effects in various disease models because of its inhibitory effect on ROS production. Therefore, we aimed to determine the effects of intravenous PC-SOD administration in a mouse model of renal injury induced by I/R. PC-SOD markedly ameliorated the I/R-induced increases in markers of renal damage (urea nitrogen, creatinine, neutrophil gelatinase-associated lipocalin, and interleukin-6) and tubular necrosis 48 h after the intervention. We also found that PC-SOD significantly ameliorated the I/R-induced increase in ROS production, using an ex vivo imaging system. Furthermore, PC-SOD inhibited the increases in expression of markers of fibrosis (α-smooth muscle actin and collagen 1A1) 96 h after, and renal fibrosis 25 days after I/R was induced. Finally, we found that PC-SOD ameliorated the I/R-induced AKI in mice with high-fat diet-induced prediabetes. These results suggest that PC-SOD inhibits AKI and the transition from AKI to CKD through the inhibition of ROS production. Therefore, we believe that PC-SOD may represent an effective therapeutic agent for I/R-induced renal injury.

Glucose Metabolism in Acute Kidney Injury and Kidney Repair

The kidneys play an indispensable role in glucose homeostasis via glucose reabsorption, production, and utilization. Conversely, aberrant glucose metabolism is involved in the onset, progression, and prognosis of kidney diseases, including acute kidney injury (AKI). In this review, we describe the regulation of glucose homeostasis and related molecular factors in kidneys under normal physiological conditions. Furthermore, we summarize recent investigations about the relationship between glucose metabolism and different types of AKI. We also analyze the involvement of glucose metabolism in kidney repair after injury, including renal fibrosis. Further research on glucose metabolism in kidney injury and repair may lead to the identification of novel therapeutic targets for the prevention and treatment of kidney diseases.