Models Of Kidney Injury Research Articles

The SIRT6/BAP1/xCT signaling axis mediates ferroptosis in cisplatin-induced AKI

BackgroundCisplatin is extensively utilized in clinical settings for treating solid tumors; However, its use is restricted because of the kidney damage caused by side effects. Moreover, currently, no effective medications have been approved to prevent or treat acute kidney injury induced by cisplatin. Our research indicates that sirtuin 6 (SIRT6) can inhibit ferroptosis induced by cisplatin, and the use of SIRT6 agonists can alleviate acute kidney injury caused by cisplatin. MethodsAn animal model of cisplatin-induced acute kidney injury (AKI) was established, followed by RNA sequencing to identify potential differentially expressed genes (DEGs) and associated pathways. To explore the role of SIRT6 in this model, SIRT6 knockout mice were generated, and recombinant adeno-associated virus was employed to achieve SIRT6 overexpression in the mice. In vitro, cells were cultured in a cisplatin-containing medium to establish a cisplatin-induced cell model. The function of SIRT6 was further investigated by overexpressing or knocking down the gene using lentiviral plasmids. To elucidate the underlying molecular mechanisms, we employed RNA sequencing, performed bioinformatics analyses, and conducted chromatin immunoprecipitation assays. ResultsRNA sequencing and Western blot analyses revealed a significant reduction in SIRT6 expression in mice with cisplatin-induced acute kidney injury (AKI). Enhancing SIRT6 expression improved renal function, reduced ferroptosis, and mitigated kidney damage, whereas SIRT6 knockout exacerbated kidney injury and heightened ferroptosis. Mechanistically, RNA sequencing, bioinformatics analysis, and chromatin immunoprecipitation assays demonstrated that SIRT6 inhibits ferroptosis by reducing the acetylation of histone H4K9ac at the BAP1 promoter. Furthermore, in vitro studies demonstrated that the SIRT6 agonist UBCS039 can alleviate cisplatin-induced acute kidney injury, highlighting its potential therapeutic role in mitigating cisplatin's damaging effects. However, further research is needed to fully elucidate the underlying mechanisms and to validate these findings in vivo. ConclusionOur findings underscore the critical role of the SIRT6/BAP1/xCT axis in regulating ferroptosis, particularly via the downregulation of SIRT6, in the context of cisplatin-induced acute kidney injury (AKI). This suggests that SIRT6 could be a promising therapeutic target for treating cisplatin-induced AKI. However, additional research is required to explore the specific mechanisms and fully assess the therapeutic potential of SIRT6 in this context.

Identification of risk factors and establishment of prediction models for mortality risk in patients with acute kidney injury: A retrospective cohort study.

This study investigated factors influencing death in patients with Acute Kidney Injury (AKI) and developed models to predict their mortality risk. We analyzed data from 1079 AKI patients admitted to Changsha First Hospital using a retrospective design. Patient information including demographics, medical history, lab results, and treatments were collected. Logistic regression models were built to identify risk factors and predict 90-day and 1-year mortality. The 90-day mortality rate among 1079 AKI patients was 13.8% (149/1079) and the one-year mortality rate was 14.8% (160/1079). For both 90-day and 1-year mortality in patients with AKI, age over 60, anemia, hypotension, organ failure, and an admission Scr level above 682.3 μmol/L were identified as independent risk factors through multivariate logistic regression analysis. Additionally, mechanical ventilation was associated with an increased risk of death at one year. To ensure the generalizability of the models, we employed a robust 5-fold cross-validation technique. Both the 90-day and 1-year mortality models achieved good performance, with area under the curve (AUC) values exceeding 0.8 in the training set. Importantly, the AUC values in the validation set (0.828 for 90-day and 0.796 for 1-year) confirmed that the models' accuracy holds true for unseen data. Additionally, calibration plots and decision curves supported the models' usefulness in predicting patient outcomes. The logistic regression models built using these factors effectively predicted 90-day and 1-year mortality risk. These findings can provide valuable insights for clinical risk management in AKI patients.

Deoxynivalenol-mediated kidney injury via endoplasmic reticulum stress in mice

ObjectiveDeoxynivalenol (DON) is a common fungal toxin that poses significant health risks to humans and animals. The present study aimed to investigate the adverse effects and molecular mechanisms of DON-induced kidney injury. MethodsMale C57BL/6 mice aged 5–6 weeks were used to establish a DON-induced acute kidney injury model. Histological analysis, biochemical assays, molecular techniques, Western blot, RNA sequencing, and transmission electron microscopy were employed to analyze kidney damage, inflammation, oxidative stress, apoptosis, and endoplasmic reticulum (ER) stress. ResultsDON disrupted kidney morphology, induced inflammatory cell infiltration, and triggered inflammatory responses. DON increased MDA content while decreasing antioxidant enzyme activity (SOD and CAT). It also triggered apoptosis, evidenced by elevated levels of caspase-12, cleaved caspase-3, and BAX, and reduced levels of Bcl-2. Transcriptomic analysis identified distinct expression patterns in 1756 genes in DON-exposed mouse kidneys, notably upregulating ER stress-related genes. Further investigation revealed ultrastructural changes in the ER and mitochondrial damage induced by DON, along with increased levels of p-IRE1, p-PERK, and their downstream targets, indicating unfolded protein response (UPR) activation in the kidney. The ER stress inhibitor 4-Phenylbutyric acid (4-PBA) significantly mitigated DON-induced ER stress, oxidative damage, apoptosis, tissue injury, ER expansion, and mitochondrial damage. ConclusionOur findings highlight the role of ER stress in DON-induced kidney injury and the protective effect of 4-PBA against these adverse effects.

Directly monitoring the dynamic in vivo metabolisms of hyperpolarized 13C-oligopeptides.

Peptides play essential roles in biological phenomena, and, thus, there is a growing interest in detecting in vivo dynamics of peptide metabolisms. Dissolution-dynamic nuclear polarization (d-DNP) is a state-of-the-art technology that can markedly enhance the sensitivity of nuclear magnetic resonance (NMR), providing metabolic and physiological information in vivo. However, the hyperpolarized state exponentially decays back to the thermal equilibrium, depending on the spin-lattice relaxation time (T1). Because of the limitation in T1, peptide-based DNP NMR molecular probes applicable in vivo have been limited to amino acids or dipeptides. Here, we report the direct detection of in vivo metabolic conversions of hyperpolarized 13C-oligopeptides. Structure-based T1 relaxation analysis suggests that the C-terminal [1-13C]Gly-d2 residue affords sufficient T1 for biological uses, even in relatively large oligopeptides, and allowed us to develop 13C-β-casomorphin-5 and 13C-glutathione. It was found that the metabolic response and perfusion of the hyperpolarized 13C-glutathione in the mouse kidney were significantly altered in a model of cisplatin-induced acute kidney injury.

Acute kidney disease in mice is associated with early cardiovascular dysfunction

Acute kidney injury (AKI) and chronic kidney disease (CKD) are major health concerns due to their increasing incidence and high mortality. They are interconnected syndromes; AKI without recovery evolves into acute kidney disease (AKD), which can indicate an AKI-to-CKD transition. Both AKI and CKD are associated with a risk of long-term cardiovascular complications, but whether vascular and cardiac dysfunctions can occur as early as the AKD period has not been studied extensively. In a mouse model of kidney injury (KI) with non-recovery, we performed vasoreactivity and echocardiography analyses on days 15 (D15) and 45 (D45) after KI. We determined the concentrations of two major gut-derived protein-bound uremic toxins known to induce cardiovascular toxicity—indoxyl sulfate (IS) and para-cresyl sulfate (PCS)—and the levels of inflammation and contraction markers on D7, D15, and D45. Mice with KI showed acute tubular and interstitial kidney lesions on D7 and D15 and chronic glomerulosclerosis on D45. They showed significant impairment of aorta relaxation and systolic-diastolic heart function, both on D15 and D45. Such dysfunction was associated with downregulation of the expression of two contractile proteins, αSMA and SERCA2a, with a more pronounced effect on D15 than on D45. KI was also followed by a rapid increase in IS and PCS serum concentrations and the expression induction of pro-inflammatory cytokines and endothelial adhesion molecules in serum and cardiovascular tissues. Therefore, these results highlight that AKD leads to early cardiac and vascular dysfunctions. How these dysfunctions could be managed to prevent cardiovascular events deserves further study.

The Nicotinic Acid Receptor HCA2 Regulates Progression of AKI and Development of CKD in Mouse Models of Sepsis and Postischemic Kidney Injury

The Nicotinic Acid Receptor HCA2 Regulates Progression of AKI and Development of CKD in Mouse Models of Sepsis and Postischemic Kidney Injury

An early and stable mouse model of polymyxin-induced acute kidney injury

BackgroundPolymyxins have been revived as a last-line therapeutic option for multi-drug resistant bacteria and continue to account for a significant proportion of global antibiotic usage. However, kidney injury is often a treatment limiting event with kidney failure rates ranging from 5 to 13%. The mechanisms underlying polymyxin-induced nephrotoxicity are currently unclear. Researches of polymyxin-associated acute kidney injury (AKI) models need to be more standardized, which is crucial for obtaining consistent and robust mechanistic results.MethodsIn this study, male C57BL/6 mice received different doses of polymyxin B (PB) and polymyxin E (PE, also known as colistin) by different routes once daily (QD), twice daily (BID), and thrice daily (TID) for 3 days. We continuously monitored the glomerular filtration rate (GFR) and the AKI biomarkers, including serum creatinine (Scr), blood urea nitrogen (BUN), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1). We also performed histopathological examinations to assess the extent of kidney injury.ResultsMice receiving PB (35 mg/kg/day subcutaneously) once daily exhibited a significant decrease in GFR and a notable increase in KIM-1 two hours after the first dose. Changes in GFR and KIM-1 at 24, 48 and 72 h were consistent and demonstrated the occurrence of kidney injury. Histopathological assessments showed a positive correlation between the severity of kidney injury and the changes in GFR and KIM-1 (Spearman’s rho = 0.3167, P = 0.0264). The other groups of mice injected with PB and PE did not show significant changes in GFR and AKI biomarkers compared to the control group.ConclusionThe group receiving PB (35 mg/kg/day subcutaneously) once daily consistently developed AKI at 2 h after the first dose. Establishing an early and stable AKI model facilitates researches into the mechanisms of early-stage kidney injury. In addition, our results indicated that PE had less toxicity than PB and mice receiving the same dose of PB in the QD group exhibited more severe kidney injury than the BID and TID groups.

Atypical Protein Kinase C Zeta Is Indispensable for Calcium Oxalate Crystal Clearance in a Dietary-Induced Mouse Model of Kidney Injury

Atypical Protein Kinase C Zeta Is Indispensable for Calcium Oxalate Crystal Clearance in a Dietary-Induced Mouse Model of Kidney Injury

Dynamic changes in the real-time glomerular filtration rate and kidney injury markers in different acute kidney injury models

In this study, we dynamically monitored the glomerular filtration rate and other assessment of renal function and markers of injury in various mice models of acute kidney injury. Male C57BL/6 mice were utilized to establish acute kidney injury models of sepsis, ischemia reperfusion, cisplatin, folic acid, aristolochic acid and antibiotic. In addition to the real time glomerular filtration rate, renal LCN-2 and HAVCR-1 mRNA expression levels, and serum creatinine, urea nitrogen and cystatin c levels were also used to evaluate renal function. In addition, the protein levels of LCN-2 and HAVCR-1 in renal, serum and urine were measured. Our results demonstrated that the changes in biomarkers always lagged the real time glomerular filtration rate during the progression and recovery of renal injury. Cystatin-c can reflect renal injury earlier than other markers, but it remains higher in the recovery stage. Perhaps the glomerular filtration rate does not reflect the greater injury caused by vancomycin plus piperacillin.

5-Hydroxytryptamine 1F Receptor Agonist Lasmiditan Differentially Regulates Successful Repair and Failed Repair Genes in a Mouse Model of Acute Kidney Injury.

Increasing evidence substantiates the role of mitochondrial dysfunction, inflammation, fibrosis, and cell senescence in the onset and progression of acute kidney injury (AKI) to chronic kidney disease . The underlying governing cellular and transcriptional events, however, are not fully understood. Recently, the key factors that regulate successful and failed repair states in the proximal tubule have been identified at a single-cell resolution following bilateral ischemia-reperfusion (I/R) in a mouse model of AKI. Previously, our group showed that treatment with the FDA-approved selective 5-hydroxytryptamine receptor 1F agonist lasmiditan following AKI induces mitochondrial biogenesis , restores renal mitochondrial function, and increases renal and vascular recovery in vivo. Here, we assessed the effect of lasmiditan on transcriptional and translational changes that are responsible for successful repair, injury, and failed repair states in the renal cortex following I/R-induced AKI. Increased levels of successful repair genes such as acyl-coA synthase medium-chain family member 2a, low-density lipoprotein receptor-related protein 2, solute carrier family 5 member 12, and hepatocyte nuclear factor 4 alpha were observed with 6 and 12 days of lasmiditan treatment following AKI compared to vehicle control. While 6 days of lasmiditan treatment had no effect on failed repair genes, the administration of lasmiditan for 12 days decreased the levels of vascular cell adhesion protein 1, tumor necrosis factor α, and interleukin-1β, which drive maladaptive repair. These data reveal that lasmiditan treatment post-AKI differentially regulates successful and failed repair gene expression in the renal cortex, likely contributing to the restoration of renal function and providing a potential targeted therapeutic pathway for the treatment of AKI.

Single-cell RNA sequencing data locate ALDH1A2-mediated retinoic acid synthetic pathway to glomerular parietal epithelial cells.

Aldehyde dehydrogenase 1, family member A2, is a retinoic acid-synthesizing enzyme encoded by Aldh1a2 in mice and ALDH1A2 in humans. This enzyme is indispensable for kidney development, but its role in kidney physiology and pathophysiology remains to be fully defined. In this review, we mined single-cell and single-nucleus RNA sequencing databases of mouse and human kidneys and found that glomerular parietal epithelial cells (PECs) express a full set of genes encoding proteins needed for cellular vitamin A uptake, intracellular transport, and metabolism into retinoic acid. In particular, Aldh1a2/ALDH1A2 mRNAs are selectively enriched in mouse and human PECs. Aldh1a2 expression in PECs is greatly increased in a mouse model of anti-glomerular basement membrane glomerulonephritis and moderately induced in a mouse model of ischemia-reperfusion acute kidney injury. Aldh1a2 expression in PECs is substantially repressed in a chronic kidney disease mouse model combining diabetes, hypertension, and partial nephrectomy and is moderately repressed in mouse models of focal segmental glomerulosclerosis and diabetic nephropathy. Single-nucleus RNA sequencing data show that ALDH1A2 mRNA expression in PECs is diminished in patients with chronic kidney disease associated with diabetes, hypertension and polycystic kidney disease. In addition to data mining, we also performed Spearman's rank correlation coefficient analyses and identified gene transcripts correlated with Aldh1a2/ALDH1A2 transcripts in mouse PECs and PEC subtypes, and in human PECs of healthy subjects and patients with AKI or CKD. Furthermore, we conducted Gene Ontology pathway analyses and identified the biological pathways enriched among these Aldh1a2/ALDH1A2-correlated genes. Our data mining and analyses led us to hypothesize that ALDH1A2-mediated retinoic acid synthesis in PECs plays a yet-undefined role in the kidney and that its dysregulation mediates injury. Conditional, PEC-selective Aldh1a2 knockout, RNA silencing and transgenic mouse models will be useful tools to test this hypothesis. Clinical studies on genetics, epigenetics, expression and functions of ALDH1A2 and other genes needed for retinoic acid biosynthesis and signaling are also warranted.

P227 MACROPHAGE TO MYOFIBROBLAST TRANSITION IN THE DEVELOPMENT OF DIASTOLIC DYSFUNCTION

Diastolic dysfunction (DD) and heart failure (HF) ravage a significant portion of the world's population. These end-stage diseases are most often precluded by hypertension (HTN). Cardiac fibrosis is one of the major factors in the degradation of cardiac function. There are multiple cellular players involved in fibrosis—including, macrophages. Indeed, in the past decade these cells have been shown to differentiate into professional fibrotic cells, myofibroblasts, a process termed macrophage to myofibroblast transition (MMT), in models of kidney injury. Despite this, the role of MMT in fibrotic remodeling in HTN and DD remains unknown. As such, we seek to investigate this phenomenon in the HTN heart and determine the role it plays in the pathological progression of HTN to DD. We utilized cardiac ultrasound and direct left ventricular (LV) pressure catheterization to gauge diastolic function. These gold-standard methods allowed us to assess cardiac function during HTN and investigate the heart at the transition to DD. Furthermore, flow cytometry was utilized to identify MMT cells (α-SMA+, CD68+) in the heart. These methods gave insight into the role that MMT plays in the degradation of heart function during HTN that inevitably leads to DD and HF. Cardiac ultrasound revealed that E/A and deceleration time (DcT) were greatly decreased in DOCA mice 10 days after the start of HTN. Further, LV pressure catheterization revealed decreased cardiac function, as shown by decreased -dp/dt. Finally, HTN and normal hearts were harvested and leukocytes isolated. Indeed α-SMA and CD68 staining showed a significant increase in MMT cells in the HTN heart. This study has shown a rapid onset of DD inside of DOCA + salt HTN mice. In addition, there was a significant increase of MMT cells in these same hearts, elucidating a novel mechanism of cardiac fibrosis. Future studies will aim to parse out the gravity of MMT in HTN to find new pharmaceutical targets against this debilitating disease.

Comprehensive ultrasonographic evaluation of normal and fibrotic kidneys in a mouse model with an ultra-high-frequency transducer.

This study aimed to establish baseline morphological and functional data for normal mouse kidneys via a clinical 33 MHz ultra-high-frequency (UHF) transducer, compare the data with the findings from fibrotic mice, and assess correlations between ultrasonography (US) parameters and fibrosis-related markers. This retrospective study aggregated data from three separate experiments (obstructive nephropathy, diabetic nephropathy, and acute-to-chronic kidney injury models). Morphological parameters (kidney size, parenchymal thickness [PT]) and functional (shear-wave speed [SWS], stiffness, resistive index [RI], and microvascular imaging-derived vascular index [VI]) were assessed and compared between normal and fibrotic mouse kidneys. Semi-quantitative histopathologic scores were calculated and molecular markers (epithelial cadherin), Collagen 1A1 [Col1A1], transforming growth factor-β, and α-smooth muscle actin [α-SMA]) were evaluated using western blots. Correlations with US parameters were explored. Clinical UHF US successfully imaged the kidneys of the experimental mice. A three-layer configuration was prevalent in the normal mouse kidney parenchyma (34/35) but was blurred in most fibrotic mouse kidneys (33/40). US parameters, including size (11.14 vs. 10.70 mm), PT (2.07 vs. 1.24 mm), RI (0.64 vs. 0.77), VI (22.55% vs. 11.47%, only for non-obstructive kidneys), SWS (1.67 vs. 2.06 m/s), and stiffness (8.23 vs. 12.92 kPa), showed significant differences between normal and fibrotic kidneys (P<0.001). These parameters also demonstrated strong discriminative ability in receiver operating characteristic curve analysis (area under the curve, 0.76 to 0.95; P<0.001). PT, VI, and RI were significantly correlated with histological fibrosis markers (ρ=-0.64 to -0.68 for PT and VI, ρ=0.71-0.76 for RI, P<0.001). VI exhibited strong negative correlations with Col1A1 (ρ=-0.76, P=0.006) and α-SMA (ρ=-0.75, P=0.009). Clinical UHF US effectively distinguished normal and fibrotic mouse kidneys, indicating the potential of US parameters, notably VI, as noninvasive markers for tracking fibrosis initiation and progression in mouse kidney fibrosis models.

Ameliorative Effects of MnO Nanoparticles on Acute Kidney Injury Model in Rats

Ameliorative Effects of MnO Nanoparticles on Acute Kidney Injury Model in Rats

Effects of live and pasteurized forms of Lactobacillus casei Zhang on acute kidney injury and chronic renal fibrosis.

Lactobacillus casei Zhang (Lac.z), isolated from traditional sour horse milk in Inner Mongolia, can alleviate various diseases and promote health. Our previous studies found that pretreatment with live Lac.z (L-Lac.z) could significantly attenuate acute kidney injury and delay the progression of chronic renal fibrosis. However, it is unknown whether these effects could be maintained by pasteurized Lac.z (P-Lac.z). Mouse models of acute kidney injury and chronic renal fibrosis induced by renal bilateral ischemia-reperfusion (BIR) surgery were treated with L-Lac.z or P-Lac.z by gavage. Serum and kidney samples were collected to analyze the extent of renal injury and fibrosis, and proteomics was used to explore the potential mechanisms underlying the differences in the effects of the two forms of Lac.z. The results revealed that treatment with L-Lac.z led to a reduction in serum urea nitrogen levels and in less renal tubular injury and subsequent renal fibrosis after BIR-induced renal injury, whereas these effects were not observed in the P-Lac.z group. Proteomic analysis revealed 19 up-regulated proteins and 39 down-regulated proteins in the P-Lac.z group, and these gene products were associated with growth and stress resistance. The specific nephroprotective effects of L-Lac.z may be independent of the interaction of live probiotics with the host.

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

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

Knockdown of long non-coding RNA SBF2-AS1 inhibits calcium oxalate-induced HK-2 cell injury by regulating the miR-302e/NLRP3 pathway.

Long non-coding ribose nucleic acids (lncRNAs) have been implicated in the development of nephrolithiasis. The study aims to investigate the interplay of lncRNA SBF2-AS1 (SETbinding factor 2 antisense RNA 1) and NLR family pyrin domain containing 3 (NLRP3) in regulating the calcium oxalate monohydrate (COM)-induced human kidney HK-2 cell injury. HK-2 cells were treated with COM (100µg/mL) to create a cellular model of kidney injury. Gene and protein expression was assessed by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blot. Proliferation and apoptosis rates, as well as levels of malondialdehyde (MDA), lactate dehydrogenase (LDH), superoxide dismutase (SOD), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were measured. Additionally, potential miRNAs interacting with SBF2-AS1 and NLRP3 were predicted utilizing the starBase and TargetScan databases. The interference of SBF2-AS1 resulted in increased cell proliferation and SOD levels in HK-2 cells after COM induction. SBF2-AS1 silencing also reduced COM-induced cell death and inflammatory cytokine production by down-regulating NLRP3 protein expression. Conversely, forced upregulation of NLRP3 abrogated the effect of SBF2-AS1 interference. Notably, SBF2-AS1 interference on COM-induced oxidative stress and COM-induced cellular damage was rescued by antioxidant, indicating the involvement of oxidative burden in COM-induced damage. miR-302e acted as a mediator miRNA linking the functional association of SBF2-AS1 and NLRP3. Silencing SBF2-AS1 promoted miR-302e level and miR-302e reduced NLRP3 expression in HK-2 cells to protect against COM-induced damage. In summary, these findings suggest that downregulation of lncRNA SBF2-AS1 can potentially protect HK-2 cells from COM-induced injury by modulating the miR-302e/NLRP3 pathway.

RIPK3 causes mitochondrial dysfunction and albuminuria in diabetic podocytopathy through PGAM5-Drp1 signaling

BackgroundReceptor-interacting protein kinase (RIPK)3 is an essential molecule for necroptosis and its role in kidney fibrosis has been investigated using various kidney injury models. However, the relevance and the underlying mechanisms of RIPK3 to podocyte injury in albuminuric diabetic kidney disease (DKD) remain unclear. Here, we investigated the role of RIPK3 in glomerular injury of DKD. MethodsWe analyzed RIPK3 expression levels in the kidneys of patients with biopsy-proven DKD and animal models of DKD. Additionally, to confirm the clinical significance of circulating RIPK3, RIPK3 was measured by ELISA in plasma obtained from a prospective observational cohort of patients with type 2 diabetes, and estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR), which are indicators of renal function, were followed up during the observation period. To investigate the role of RIPK3 in glomerular damage in DKD, we induced a DKD model using a high-fat diet in Ripk3 knockout and wild-type mice. To assess whether mitochondrial dysfunction and albuminuria in DKD take a Ripk3-dependent pathway, we used single-cell RNA sequencing of kidney cortex and immortalized podocytes treated with high glucose or overexpressing RIPK3. ResultsRIPK3 expression was increased in podocytes of diabetic glomeruli with increased albuminuria and decreased podocyte numbers. Plasma RIPK3 levels were significantly elevated in albuminuric diabetic patients than in non-diabetic controls (p = 0.002) and non-albuminuric diabetic patients (p = 0.046). The participants in the highest tertile of plasma RIPK3 had a higher incidence of renal progression (hazard ratio [HR] 2.29 [1.05–4.98]) and incident chronic kidney disease (HR 4.08 [1.10–15.13]). Ripk3 knockout improved albuminuria, podocyte loss, and renal ultrastructure in DKD mice. Increased mitochondrial fragmentation, upregulated mitochondrial fission-related proteins such as phosphoglycerate mutase family member 5 (PGAM5) and dynamin-related protein 1 (Drp1), and mitochondrial ROS were decreased in podocytes of Ripk3 knockout DKD mice. In cultured podocytes, RIPK3 inhibition attenuated mitochondrial fission and mitochondrial dysfunction by decreasing p-mixed lineage kinase domain-like protein (MLKL), PGAM5, and p-Drp1 S616 and mitochondrial translocation of Drp1. ConclusionsThe study demonstrates that RIPK3 reflects deterioration of renal function of DKD. In addition, RIPK3 induces diabetic podocytopathy by regulating mitochondrial fission via PGAM5-Drp1 signaling through MLKL. Inhibition of RIPK3 might be a promising therapeutic option for treating DKD.

Role of mitochondria in endogenous renal repair.

Renal tubules have potential to regenerate and repair after mild-to-moderate injury. Proliferation of tubular epithelial cells represents the initial step of this reparative process. Although for many years, it was believed that proliferating cells originated from a pre-existing intra-tubular stem cell population, there is now consensus that surviving tubular epithelial cells acquire progenitor properties to regenerate the damaged kidney. Scattered tubular-like cells (STCs) are dedifferentiated adult renal tubular epithelial cells that arise upon injury and contribute to renal self-healing and recovery by replacing lost neighboring tubular epithelial cells. These cells are characterized by the co-expression of the stem cell surface markers CD133 and CD24, as well as mesenchymal and kidney injury markers. Previous studies have shown that exogenous delivery of STCs ameliorates renal injury and dysfunction in murine models of acute kidney injury, underscoring the regenerative potential of this endogenous repair system. Although STCs contain fewer mitochondria than their surrounding terminally differentiated tubular epithelial cells, these organelles modulate several important cellular functions, and their integrity and function are critical to preserve the reparative capacity of STCs. Recent data suggest that the microenviroment induced by cardiovascular risk factors, such as obesity, hypertension, and renal ischemia may compromise STC mitochondrial integrity and function, limiting the capacity of these cells to repair injured renal tubules. This review summarizes current knowledge of the contribution of STCs to kidney repair and discusses recent insight into the key role of mitochondria in modulating STC function and their vulnerability in the setting of cardiovascular disease.

Machine learning-based prediction of off-pump coronary artery bypass grafting-associated acute kidney injury.

The cardiac surgery-associated acute kidney injury (CSA-AKI) occurs in up to 1 out of 3 patients. Off-pump coronary artery bypass grafting (OPCABG) is one of the major cardiac surgeries leading to CSA-AKI. Early identification and timely intervention are of clinical significance for CSA-AKI. In this study, we aimed to establish a prediction model of off-pump coronary artery bypass grafting-associated acute kidney injury (OPCABG-AKI) after surgery based on machine learning methods. The preoperative and intraoperative data of 1,041 patients who underwent OPCABG in Chest Hospital, Tianjin University from June 1, 2021 to April 30, 2023 were retrospectively collected. The definition of OPCABG-AKI was based on the 2012 Kidney Disease Improving Global Outcomes (KDIGO) criteria. The baseline data and intraoperative time series data were included in the dataset, which were preprocessed separately. A total of eight machine learning models were constructed based on the baseline data: logistic regression (LR), gradient-boosting decision tree (GBDT), eXtreme gradient boosting (XGBoost), adaptive boosting (AdaBoost), random forest (RF), support vector machine (SVM), k-nearest neighbor (KNN), and decision tree (DT). The intraoperative time series data were extracted using a long short-term memory (LSTM) deep learning model. The baseline data and intraoperative features were then integrated through transfer learning and fused into each of the eight machine learning models for training. Based on the calculation of accuracy and area under the curve (AUC) of the prediction model, the best model was selected to establish the final OPCABG-AKI risk prediction model. The importance of features was calculated and ranked by DT model, to identify the main risk factors. Among 701 patients included in the study, 73 patients (10.4%) developed OPCABG-AKI. The GBDT model was shown to have the best predictions, both based on baseline data only (AUC =0.739, accuracy: 0.943) as well as based on baseline and intraoperative datasets (AUC =0.861, accuracy: 0.936). The ranking of importance of features of the GBDT model showed that use of insulin aspart was the most important predictor of OPCABG-AKI, followed by use of acarbose, spironolactone, alfentanil, dezocine, levosimendan, clindamycin, history of myocardial infarction, and gender. A GBDT-based model showed excellent performance for the prediction of OPCABG-AKI. The fusion of preoperative and intraoperative data can improve the accuracy of predicting OPCABG-AKI.