Injury Chronic Kidney Disease Research Articles

Cuproptosis associated cytoskeletal destruction contributes to podocyte injury in chronic kidney disease.

The podocyte cytoskeleton determines the stability of podocyte structure and function, and their imbalance plays a pathogenic role in podocyte diseases. However, the underlying mechanism of podocyte cytoskeleton damage is not fully understood. Here, we investigate the specific role of cuproptosis in inducing podocyte cytoskeleton injury. In vitro and in vivo studies, exposure to high levels of copper and adriamycin (ADR) caused significant increases in copper concentration in intracellular and renal tissue. Moreover, excessive accumulation of copper induced cuproptosis, resulting in the destruction of the podocyte cytoskeleton. However, inhibition of copper accumulation to reduce cuproptosis also significantly alleviated the damage of podocyte cytoskeleton. In addition, inhibition of cuproptosis mitigated ADR-induced mitochondrial damage as well as the production of reactive oxygen species and depolarization of mitochondrial membrane potential, and restored ATP synthesis. Among the transcriptome sequencing data, the difference of CXCL5 was the most significant. Both high copper and ADR exposure can cause up-regulation of CXCL5, and CXCL5 deletion inhibits the occurrence of cuproptosis, thereby alleviating the podocyte cytoskeleton damage. This suggests that CXCL5 may act upstream of cuproptosis that mediates podocyte cytoskeleton damage. In conclusion, cuproptosis induced by excessive copper accumulation may induce podocyte cytoskeleton damage by promoting mitochondrial dysfunction, thereby causing podocyte injury. This indicates that cuproptosis plays an important role in the pathogenesis of podocyte injury and provides a basis for seeking potential targets for the treatment of chronic kidney disease.

#3011 Pathophysiological link between renal and cardiovascular disease in patients with type 2 diabetes mellitus: preliminary results from a proteomic study

Abstract Background and Aims Diabetic kidney disease (DKD) affects nearly 40% of people with diabetes and is the leading cause of chronic kidney disease (CKD). A high prevalence of cardiovascular disease (CVD) is known in this population. Indeed, DKD and CVD are often related and lead to worse outcomes in type 2 diabetes mellitus (T2D), i.e. cardiac fibrosis and CV events are frequently described in patients with DKD. However, specific associations and accurate prediction biomarkers for DKD and CVD progression in T2D are still lacking as various proteins may play a multi-mechanistic role. Lipocalin-2 (LCN2) is involved in several pathophysiological processes (inflammation, renal disease and cardiometabolic complications in CKD). Its leukocyte-chemoattractant effect has shown to reduce CVD in experimental models of cardiomyopathy when suppressed. Excess LCN2 in CKD is a determinant of disease progression, but also a potent mediator of cardiac injury in CKD. Insulin-like growth factor binding proteins (IGFBPs) also play an important role in cell homeostasis by regulating cell transcription, migration, and apoptosis. IGFBP-3 down-regulation has demonstrated to be a predictor of rapid renal progression in T2DM. On the other hand, IGFBP-6 increases when GFR drops, being involved in the pathophysiological process of CKD as an apoptosis-inducing protein In this context, a proteomic-based approach would optimise the clinical utility of multiple plasma biomarkers. The aim was to identify proteins associated with DKD, cardiac fibrosis (estimated by the PICP biomarker) and the presence of a new CV event. Method A prospective cohort of 91 T2D patients, with a minimum follow-up of 3 years (mean: 4 years) was analysed. We evaluated the association between rates of change in GFR and PICP during follow-up (fold-change: end/initial) and their interaction with the development of a composite of cardiovascular (CV) events: CV death, stroke, ischaemic heart disease, atrial fibrillation, valvular heart disease and CV-related hospitalisation. In addition, ninety-two proteins were quantified in serum samples using a multiplex proximity extension assay with high-throughput protein detection technology (Olink proteomics, Cardiometabolic panel). Associations between variations in these proteins and changes in PICP and eGFR (all expressed as fold change from baseline) were assessed using linear regression analyses adjusted for their respective baseline values. All analyses were adjusted by multiple testing (Benjamini-Hochberg, FDR = 0.05%) using R software. Results Sixty-eight (74.7%) men and 23 (25.3%) women were included in the analysis. The mean age at baseline was 65.8 years, and the mean follow-up was 4 years (minimum 3 years). Sixteen cardiovascular events were recorded. An inverse association was observed between GFR and PICP (p = 0.003). Interaction analysis showed that this correlation occurred only in patients with incident CV events (p for interaction <0.001) (Fig. 1). By proteomic analysis (Fig. 2) several proteins were found to be significantly related to one of the three parameters studied (change in GFR, change in PICP and change with cardiovascular event), of which 3 proteins presented an overlap for all the parameters analysed: Lipocalin 2 (LCN2) and Insulin-like growth factor binding proteins 3 and 6 (IGFBP3 and IGFBP6). Interestingly, LCN2 and IGFBP6 were more highly expressed in patients with CV events whereas IGFBP3 was downregulated in these patients. Conclusion In patients with DKD, worsening enal function is associated with elevated circulating levels of the collagen synthesis biomarker PICP, particularly in those who developed at least one CV event. The link shown with LCN2, IGFBP-6 and IGFBP-3 shed light on possible multi-mechanistic pathways involved in DKD and narrow the scope towards a common pathway involving an interaction between pro-apoptotic and local inflammatory factors.

Circadian light/dark cycle reversal exacerbates the progression of chronic kidney disease in mice.

Circadian disruption such as shift work, jet lag, has gradually become a global health issue and is closely associated with various metabolic disorders. The influence and mechanism of circadian disruption on renal injury in chronic kidney disease (CKD) remains inadequately understood. Here, we evaluated the impact of environmental light disruption on the progression of chronic renal injury in CKD mice. By using two abnormal light exposure models to induce circadian disruption, we found that circadian disruption induced by weekly light/dark cycle reversal (LDDL) significantly exacerbated renal dysfunction, accelerated renal injury, and promoted renal fibrosis in mice with 5/6 nephrectomy and unilateral ureteral obstruction (UUO). Mechanistically, RNA-seq analysis revealed significant immune and metabolic disorder in the LDDL-conditioned CKD kidneys. Consistently, renal content of ATP was decreased and ROS production was increased in the kidney tissues of the LDDL-challenged CKD mice. Untargeted metabolomics revealed a significant buildup of lipids in the kidney affected by LDDL. Notably, the level of β-NMN, a crucial intermediate in the NAD+ pathway, was found to be particularly reduced. Moreover, we demonstrated that both β-NMN and melatonin administration could significantly rescue the light-disruption associated kidney dysfunction. In conclusion, environmental circadian disruption may exacerbate chronic kidney injury by facilitating inflammatory responses and disturbing metabolic homeostasis. β-NMN and melatonin treatments may hold potential as promising approaches for preventing and treating light-disruption associated CKD.

Shen Shuai II recipe improves renal hypoxia to attenuate renal injury in 5/6 renal ablation/infarction rats and effect evaluation using blood oxygenation level-dependent functional magnetic resonance imaging

Background: Renal hypoxia plays a key role in the progression of chronic kidney disease (CKD). Shen Shuai II Recipe (SSR) has shown good results in the treatment of CKD as a common herbal formula. This study aimed to explore the effect of SSR on renal hypoxia and injury in CKD rats. Methods: Twenty-five Wistar rats underwent 5/6 renal ablation/infarction (A/I) surgery were randomly divided into three groups: 5/6 (A/I), 5/6 (A/I) + losartan (LOS), and 5/6 (A/I) + SSR groups. Another eight normal rats were used as the Sham group. After 8-week corresponding interventions, blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) was performed to evaluate renal oxygenation in all rats, and biochemical indicators were used to measure kidney and liver function, hemoglobin, and proteinuria. The expression of fibrosis and hypoxia-related proteins was analyzed using immunoblotting examination. Results: Renal oxygenation, evaluated by BOLD-fMRI as cortical and medullary T2* values (COT2* and MET2*), was decreased in 5/6 (A/I) rats, but increased after SSR treatment. SSR also downregulated the expression of hypoxia-inducible factor-1α (HIF-1α) in 5/6 (A/I) kidneys. With the improvement of renal hypoxia, renal function and fibrosis were improved in 5/6 (A/I) rats, accompanied by reduced proteinuria. Furthermore, the COT2* and MET2* were significantly positively correlated with the levels of creatinine clearance rate (Ccr) and hemoglobin, but negatively associated with the levels of serum creatinine (SCr), blood urea nitrogen (BUN), serum cystatin C (CysC), serum uric acid (UA), 24-h urinary protein (24-h Upr), and urinary albumin:creatinine ratio (UACR). Conclusion: The degree of renal oxygenation reduction is correlated with the severity of renal injury in CKD. SSR can improve renal hypoxia to attenuate renal injury in 5/6 (A/I) rats of CKD.

Therapeutic role of miR-26a on cardiaorenal injury in mice model of angiotensin-II induced chronic kidney disease through inhibition of LIMS1/ILK pathway.

Chronic kidney disease (CKD) is associated with common pathophysiological processes, such as inflammation and fibrosis, in both the heart and the kidney. However, the underlying molecular mechanisms that drive these processes are not yet fully understood. Therefore, this study focused on the molecular mechanism of heart and kidney injury in CKD. We generated a microRNA (miR)-26a knockout (KO) mouse model to investigate the role of miR-26a in angiotensin (Ang)-II-induced cardiac and renal injury. We performed Ang-II modeling in wild type (WT) mice and miR-26a KO mice, with six mice in each group. In addition, Ang-II-treated AC16 cells and HK2 cells were used as in vitro models of cardiac and renal injury in the context of CKD. Histological staining, immunohistochemistry, quantitative real-time polymerase chain reaction (PCR), and Western blotting were applied to study the regulation of miR-26a on Ang-II-induced cardiac and renal injury. Immunofluorescence reporter assays were used to detect downstream genes of miR-26a, and immunoprecipitation was employed to identify the interacting protein of LIM and senescent cell antigen-like domain 1 (LIMS1). We also used an adeno-associated virus (AAV) to supplement LIMS1 and explored the specific regulatory mechanism of miR-26a on Ang-II-induced cardiac and renal injury. Dunnett's multiple comparison and t-test were used to analyze the data. Compared with the control mice, miR-26a expression was significantly downregulated in both the kidney and the heart after Ang-II infusion. Our study identified LIMS1 as a novel target gene of miR-26a in both heart and kidney tissues. Downregulation of miR-26a activated the LIMS1/integrin-linked kinase (ILK) signaling pathway in the heart and kidney, which represents a common molecular mechanism underlying inflammation and fibrosis in heart and kidney tissues during CKD. Furthermore, knockout of miR-26a worsened inflammation and fibrosis in the heart and kidney by inhibiting the LIMS1/ILK signaling pathway; on the contrary, supplementation with exogenous miR-26a reversed all these changes. Our findings suggest that miR-26a could be a promising therapeutic target for the treatment of cardiorenal injury in CKD. This is attributed to its ability to regulate the LIMS1/ILK signaling pathway, which represents a common molecular mechanism in both heart and kidney tissues.

Mosaic loss of Y chromosome is associated with aging and epithelial injury in chronic kidney disease

BackgroundMosaic loss of Y chromosome (LOY) is the most common chromosomal alteration in aging men. Here, we use single-cell RNA and ATAC sequencing to show that LOY is present in the kidney and increases with age and chronic kidney disease.ResultsThe likelihood of a cell having LOY varies depending on its location in the nephron. Cortical epithelial cell types have a greater proportion of LOY than medullary or glomerular cell types, which may reflect their proliferative history. Proximal tubule cells are the most abundant cell type in the cortex and are susceptible to hypoxic injury. A subset of these cells acquires a pro-inflammatory transcription and chromatin accessibility profile associated with expression of HAVCR1, VCAM1, and PROM1. These injured epithelial cells have the greatest proportion of LOY and their presence predicts future kidney function decline. Moreover, proximal tubule cells with LOY are more likely to harbor additional large chromosomal gains and express pro-survival pathways. Spatial transcriptomics localizes injured proximal tubule cells to a pro-fibrotic microenvironment where they adopt a secretory phenotype and likely communicate with infiltrating immune cells.ConclusionsWe hypothesize that LOY is an indicator of increased DNA damage and potential marker of cellular senescence that can be applied to single-cell datasets in other tissues.

Acute kidney injury in hospitalized adults with chronic kidney disease: comparing cROCK, KDIGO, and combined criteria.

Acute-on-chronic kidney disease (ACKD) increases the risk of progression of chronic kidney disease (CKD). This study aimed to evaluate the ability of a novel criteria of reference change value of the serum creatinine optimized criteria for acute kidney injury in CKD (cROCK) to detect ACKD patients. This was a retrospective observational study with a 3-year follow-up. All included patients with CKD stage 3 were evaluated using cROCK, Kidney Disease Improving Global Outcomes (KDIGO), and their combined criteria. The renal composite endpoints, major adverse cardiovascular events (MACEs), and all-cause mortality were recorded as clinical outcomes. A total of 812 patients was enrolled. The cROCK criteria detected more ACKD events than did the KDIGO (68.0% vs. 59.5%, p < 0.001). Compared to KDIGO (-) & cROCK (-) group, ACKD patients diagnosed by cROCK had significantly higher hazard ratio [HR] for renal composite endpoints (HR, 3.591; p < 0.001), MACEs (HR, 1.748; p < 0.001), and all-cause mortality (HR, 2.985; p < 0.001). The patients in KDIGO (+) & cROCK (+) group had the lowest survival probability when considering renal composite endpoints, MACEs, and all-cause mortality (all p < 0.001). Furthermore, cROCK resulted in the largest area under the receiver operating characteristic curve (AUC) for predicting renal composite endpoints, and the combined criteria led to the largest AUC for predicting MACEs and allcause mortality. Compared to the KDIGO, the cROCK detected more ACKD events. Combining both cROCK and KDIGO criteria might improve the predictive ability for long-term outcomes in ACKD patients.

Determination of serum KIM-1 in patients with chronic kidney injury

Background: Chronic kidney disease (CKD) affects more than 800 million people worldwide and is one of the leading non-communicable causes of death. Despite being a latent issue, once renal damage has started, the disease can rapidly progress to an advanced stage. Aims and Objectives: Currently, the most commonly used markers for the diagnosis of renal disease are non-specific and insensitive. As a result, the goal of the current study is to investigate whether KIM-1 could be a precise and sensitive biomarker for identifying early kidney injury in CKD patients. Materials and Methods: This case–control study recruited 155 participants from the Index Medical College Hospital v Research Centre, Indore, Madhya Pradesh, based on inclusion and exclusion criteria. 150 non-CKD subjects matched for age and sex were also taken from the hospital. The levels of KIM-1 were compared between CKD and non-CKD participants. Serum creatinine, urea, and creatinine clearance were also measured. Results: The levels of KIM-1 were substantially higher in CKD patients than in non-CKD participants. In addition, a negative relationship between KIM-1 and creatinine clearance was observed with a P<0.05. Conclusion: KIM-1 is a precise and sensitive kidney injury biomarker that can identify early kidney injury in CKD and contribute to the progression of interstitial fibrosis in kidney disease.

#6814 A NEW SORBENT DEVICE FOR MULTIPLE CLINICAL PURPOSES: CURRENT EVIDENCE AT A PRIVATE HOSPITAL IN MEXICO

Abstract Background and Aims Adsorption is an extracorporeal technique utilized for blood purification, it also complements convection and diffusion for solute removal. Since 1991 we had used blood purification techniques, over the years, new adsorption cartridges had been developed, the new ones involving treatment for inflammatory conditions, chronic uremic symptoms and autoimmune diseases. HA130, HA230, and HA330 (Jafron, Zhuhai City, China) are among the widely used adsorption cartridges in China. We report highlights of the use of hemoperfusion using HA130 cartridges in the Mexican population cohorts in the context of multiple chronic inflammatory conditions in order to support evidence of effectiveness and safety. Method We retrospectively analyzed the medical records of 14 critically ill patients in the context of chronic inflammatory conditions such as acute kidney injury in chronic kidney disease, acute lung injury due to SARS-COV-2 infection and sepsis. Hemoperfusion in addition to standard therapy (fluid resuscitation, vasopressors, antimicrobial therapy and ventilatory support) resulted in the improvement of inflammatory substances levels when compared to standard therapy alone. Out of the 14 patients, 7 patients used HA130 cartridges and 7 patients with standard therapy alone. Results There were no significant side effects associated with HA130 cartridge use. HA 130 cartridges were found to be effective in reducing uremic symptoms in chronic hemodialysis patients, improvement of pruritus score and decreased parathyroid hormone and phosphate product (p<0.5) when compared to HD alone, creatinine (MARS: −24 μmol/L, −19.5 to −10.46, p < 0.001; SPAD: −2 μmol/L, −9.0 to +7.0/L, p = 0.314) and urea (MARS: −0.9 mmol/L, −318 to −0.189, p = 0.024; SPAD: −0.1 mmol/L, −1.0 to +0.68, p = 0.523). 66.6% of cost-effectiveness when compared to standard therapy. Conclusion In the group of patients that used HA130 cartridges we found statistically significant (p <0.05) reduction of pruritus score, PTH, phosphate product, creatine and urea when compared to the group of patients with standard therapy alone. The development in new cartridges technology allows more wide applications for renal patients. As we expand to involve other indications for this therapy there is cost-effectiveness improvement for the patients.More studies in different clinical settings are needed in order to achieve adsorption therapy national recommendations. We also found that the HA130 cartridges are effective in reducing uremic symptoms and microinflammatory status in acute kidney injury in chronic kidney disease patients due to the elimination of middle and small molecule uremic toxins and inflammatory mediators and endotoxins. This may translate as an improvement of quality of life and survive rates in patients with chronic hemodialysis, even though more studies are needed in order to prove this assumption.

Tissue Sodium Accumulation Induces Organ Inflammation and Injury in Chronic Kidney Disease.

High salt intake is a primary cause of over-hydration in chronic kidney disease (CKD) patients. Inflammatory markers are predictors of CKD mortality; however, the pathogenesis of inflammation remains unclear. Sodium storage in tissues has recently emerged as an issue of concern. The binding of sodium to tissue glycosaminoglycans and its subsequent release regulates local tonicity. Many cell types express tonicity-responsive enhancer-binding protein (TonEBP), which is activated in a tonicity-dependent or tonicity-independent manner. Macrophage infiltration was observed in the heart, peritoneal wall, and para-aortic tissues in salt-loading subtotal nephrectomized mice, whereas macrophages were not prominent in tap water-loaded subtotal nephrectomized mice. TonEBP was increased in the heart and peritoneal wall, leading to the upregulation of inflammatory mediators associated with cardiac fibrosis and peritoneal membrane dysfunction, respectively. Reducing salt loading by a diuretic treatment or changing to tap water attenuated macrophage infiltration, TonEBP expression, and inflammatory marker expression. The role of TonEBP may be crucial during the cardiac fibrosis and peritoneal deterioration processes induced by sodium overload. Anti-interleukin-6 therapy improved cardiac inflammation and fibrosis and peritoneal membrane dysfunction. Further studies are necessary to establish a strategy to regulate organ dysfunction induced by TonEBP activation in CKD patients.

DNA-damaged podocyte-CD8 T cell crosstalk exacerbates kidney injury by altering DNA methylation

Recent epigenome-wide studies suggest an association between blood DNA methylation and kidney function. However, the pathological importance remains unclear. Here, we show that the homing endonuclease I-PpoI-induced DNA double-strand breaks in kidney glomerular podocytes cause proteinuria, glomerulosclerosis, and tubulointerstitial fibrosis with DNA methylation changes in blood cells as well as in podocytes. Single-cell RNA-sequencing analysis reveals an increase in cytotoxic CD8+ Tcells with the activating/costimulatory receptor NKG2D in the kidneys, which exhibit a memory precursor effector cell phenotype, and the CD44high memory CD8+ Tcells are also increased in the peripheral circulation. NKG2D blockade attenuates the renal phenotype caused by podocyte DNA damage. Blood methylome shows increased DNA methylation in binding sites for STAT1, a transcription factor contributing to CD8+ Tcell homeostasis. Collectively, podocyte DNA damage alters the blood methylome, leading to changes in CD8+ Tcells, which contribute to sustained renal injury in chronic kidney disease.

Arterial spin labeling and diffusion-weighted MR imaging: quantitative assessment of renal pathological injury in chronic kidney disease.

The aim of the study was to investigate the performance of arterial spin labeling (ASL), diffusion-weighted imaging (DWI), and clinical biomarkers in assessing renal pathological injury in CKD. Forty-five biopsy-proven CKD patients and 17 healthy volunteers underwent DWI and ASL examinations. Renal cortical blood flow (RBF) and apparent diffusion coefficient (ADC) values were acquired. Correlations between RBF, ADC, serum creatinine (SCr), estimated glomerular filtration rate (eGFR), and pathological scores were assessed. The diagnostic efficacy of SCr, eGFR, RBF, and ADC in assessing renal pathological injury was assessed by ROC curve analysis. The cortical RBF, ADC, SCr, and eGFR were significantly correlated with the renal histology score (all p < 0.01). The AUC values of SCr, eGFR, RBF, and ADC were 0.705 (95% confidence interval (CI): 0.536-0.827), 0.718 (0.552-0.839), 0.823 (0.658-0.916), and 0.624 (0.451-0.786), respectively, in discriminating the minimal-mild renal pathological injury group (N = 30) from the control group (N = 17). The diagnostic ability of ASL was significantly higher than that of DWI (p = 0.049) and slightly but not significantly higher than that of eGFR and SCr (p = 0.151 and p = 0.129, respectively). When compared with that of eGFR, the sensitivity of ASL in detecting early renal injury increased from 50 to 70% (p = 0.014). However, in differentiating between the minimal-mild and moderate-severe renal injury groups (N = 15), there was no significant difference in diagnostic ability among the four parameters (all p > 0.05). ASL is practicable for noninvasive evaluation of renal pathology, especially for predicting early renal pathological injury in CKD patients.

Value of T1 Mapping in the Non-invasive Assessment of Renal Pathologic Injury for Chronic Kidney Disease Patients.

The objective of this study was to evaluate renal function and pathologic injury in chronic kidney disease (CKD) using T1 mapping. We recruited fifteen healthy volunteers (HV) and seventy-five CKD patients to undergo T1 mapping examination, and renal parenchymal T1 values were measured. Spearman correlation analysis was used to evaluate the relevance between the pathologic injury score, estimated glomerular filtration rate (eGFR), and renal parenchymal T1 values. The diagnostic efficiency of T1 value in evaluating renal pathologic impairment was assessed. In all subjects, renal cortical T1 value was remarkably lower than renal medullary T1 value (P < 0.01). The renal medullary T1 value of HV was considerably lower than that of CKD patients in all stages (P < 0.05). The T1 values were negatively correlated with eGFR (cortex, r = -0.718; medulla, r = -0.645). The T1 values were positively correlated with glomerular injury score (cortex, r = 0.692; medulla, r = 0.632), tubulointerstitial injury score (cortex, r = 0.758; medulla, r = 0.690) (all P < 0.01). The area under the curve (AUC) of renal cortical and medullary T1 values were 0.914 and 0.880 to distinguish moderate-severe from mild renal injury groups. To differentiate mild renal injury group from control group, the AUC values of renal cortical and medullary T1 values were 0.879 and 0.856. T1 mapping has potential application value in non-invasively assessing renal pathologic injury in CKD.

Capability of arterial spin labeling and intravoxel incoherent motion diffusion-weighted imaging to detect early kidney injury in chronic kidney disease.

To prospectively investigate the capability of arterial spin labeling (ASL) and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) for the identification of early kidney injury in chronic kidney disease (CKD) patients with normal estimated glomerular filtration rate (eGFR). Fifty-four CKD patients confirmed by renal biopsy (normal eGFR group [eGFR ≥ 90 mL/min/1.73 m2]: n = 26; abnormal eGFR group [eGFR < 90 mL/min/1.73 m2]: n = 28) and 20 healthy volunteers (HV) were recruited. All subjects were examined by IVIM-DWI and ASL imaging. Renal blood flow (RBF) derived from ASL, true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) derived from IVIM-DWI were measured from the renal cortex. One-way analysis of variance was used to compare MRI parameters among the three groups. The correlation between eGFR and MRI parameters was evaluated by Spearman correlation analysis. Diagnostic performances of MRI parameters for detecting kidney injury were assessed by receiver operating characteristic (ROC) curves. The renal cortical D, D*, f, and RBF values showed statistically significant differences among the three groups. eGFR was positively correlated with MRI parameters (D: r = 0.299, D*: r = 0.569, f: r = 0.733, RBF: r = 0.586). The areas under the curve (AUCs) for discriminating CKD patients from HV were 0.725, 0.752, 0.947, and 0.884 by D, D*, f, and RBF, respectively. D, D*, f, RBF, and eGFR identified CKD patients with normal eGFR with AUCs of 0.735, 0.612, 0.917, 0.827, and 0.733, respectively, and AUC of f value was significantly larger than that of eGFR. IVIM-DWI and ASL were useful for detecting underlying pathologic injury in early CKD patients with normal eGFR. • The renal cortical f and RBF values in the control group were significantly higher than those in the normal eGFR group. • A negative correlation was observed between the renal cortical D, D*, f, and RBF values and SCr and 24 h-UPRO, while eGFR was significantly positively correlated with renal cortical D, D*, f, and RBF values. • The AUC of renal cortical f values was statistically larger than that of eGFR for the discrimination between the CKD with normal eGFR group and the control group.

Salt taste threshold and contributory factors of chronic kidney disease patients: a cross-sectional study.

High salt intake, correlated with high salt taste threshold, may accelerate renal injury in chronic kidney disease (CKD) patients. However, few studies have focused on factors that influence salt taste threshold. Therefore, we aimed to identify factors that influence the salt taste threshold of CKD patients, to provide more precise salt restriction recommendations in dietary therapy. Between April 2016 and March 2019, we measured the salt taste threshold of 1019 CKD patients, aged 22-78years, from 52 hospitals across southwestern China, and then we performed a cross-sectional study. The mean salt taste threshold was 0.37 ± 0.16% NaCl. There were 115 (11.3%), 670 (65.7%), and 234 (23.0%), respectively, patients who had low (≤ 0.1% NaCl), medium (0.1-0.4% NaCl), and high (> 0.4% NaCl) salt taste thresholds. One-way ANOVA and regression results revealed that sex (male), age, decreased estimated glomerular filtration rate, and absence of salt restriction were factors that influenced CKD groups with high salt taste threshold. We found an independent correlation between contributory factors including sex, age, eGFR, and salt restriction behavior of subjects with the salt taste threshold of CKD patients. Our findings also offer insights on salt taste thresholds that could be useful for clinicians advising salt restriction to impair the salt taste sensitivity of the corresponding populations.

Activation of the Nrf2/ARE signaling pathway protects against palmitic acid-induced renal tubular epithelial cell injury by ameliorating mitochondrial reactive oxygen species-mediated mitochondrial dysfunction.

Chronic kidney disease (CKD) is often accompanied by dyslipidemia, and abnormal lipid metabolism in proximal tubule cells is considered closely related to the dysfunction of proximal tubule cells and eventually leads to accelerated kidney damage. Nuclear factor E2-related factor 2 (Nrf2), known as a redox-sensitive transcription factor, is responsible for regulating cellular redox homeostasis. However, the exact role of Nrf2 in dyslipidemia-induced dysfunction of proximal tubule cells is still not fully elucidated. In the present study, we showed that palmitic acid (PA) induced mitochondrial damage, excessive mitochondrial reactive oxygen species (ROS) (mtROS) generation, and cell injury in HK-2 cells. We further found that mtROS generation was involved in PA-induced mitochondrial dysfunction, cytoskeletal damage, and cell apoptosis in HK-2 cells. In addition, we demonstrated that the Nrf2/ARE signaling pathway was activated in PA-induced HK-2 cells and that silencing Nrf2 dramatically aggravated PA-induced mtROS production, mitochondrial damage, cytoskeletal damage and cell apoptosis in HK-2 cells. However, the mitochondrial antioxidant MitoTEMPOL effectively eliminated these negative effects of Nrf2 silencing in HK-2 cells under PA stimulation. Moreover, activation of the Nrf2/ARE signaling pathway with tBHQ attenuated renal injury, significantly reduced mtROS generation, and improved mitochondrial function in rats with HFD-induced obesity. Taken together, these results suggest that the Nrf2/ARE-mediated antioxidant response plays a protective role in hyperlipidemia-induced renal injury by ameliorating mtROS-mediated mitochondrial dysfunction and that enhancing Nrf2 antioxidant signaling provides a potential therapeutic strategy for kidney injury in CKD with hyperlipidemia.

Angiotensin II induces podocyte metabolic reprogramming from glycolysis to glycerol-3-phosphate biosynthesis

Recent studies have reported that Angiotensin II (Ang II) contributes to podocyte injury by interfering with metabolism. Glycolysis is essential for podocytes and glycolysis abnormality is associated with glomerular injury in chronic kidney disease (CKD). Glycerol-3-phosphate (G-3-P) biosynthesis is a shunt pathway of glycolysis, in which cytosolic glycerol-3-phosphate dehydrogenase 1 (GPD1) catalyzes dihydroxyacetone phosphate (DHAP) to generate G-3-P in the presence of the NADH. G-3-P is not only a substrate in glycerophospholipids and glyceride synthesis but also can be oxidated by mitochondrial glycerol-3-phosphate dehydrogenase (GPD2) to regenerate DHAP in mitochondria. Since G-3-P biosynthesis links to glycolysis, mitochondrial metabolism and lipid synthesis, we speculate G-3-P biosynthesis abnormality is probably involved in podocyte injury. In this study, we demonstrated that Ang II upregulated GPD1 expression and increased G-3-P and glycerophospholipid syntheses in podocytes. GPD1 knockdown protected podocytes from Ang II-induced lipid accumulation and mitochondrial dysfunction. GPD1 overexpression exacerbated Ang II-induced podocyte injury. In addition, we proved that lipid accumulation and mitochondrial dysfunction were correlated with G-3-P content in podocytes. These results suggest that Ang II upregulates GPD1 and promotes G-3-P biosynthesis in podocytes, which promote lipid accumulation and mitochondrial dysfunction in podocytes.

Covert vascular brain injury in chronic kidney disease

Chronic kidney disease (CKD) contributes to the increased risk of stroke and dementia. Accumulating evidence indicates that structural brain abnormalities, such as cerebral small vessel disease, including white matter hyperintensities, lacunes, perivascular spaces, and cerebral microbleeds, as well as brain atrophy, are common in patients with CKD. All of these imaging findings have been implicated in the development of stroke and dementia. The brain and kidney exhibit similar impairments and promote structural brain abnormalities due to shared vascular risk factors and similar anatomical and physiological susceptibility to vascular injury in patients with CKD. This indicates that kidney function has a significant effect on brain aging. However, as most results are derived from cross-sectional observational studies, the exact pathophysiology of structural brain abnormalities in CKD remains unclear. The early detection of structural brain abnormalities in CKD in the asymptomatic or subclinical phase (covert) should enable stroke risk prediction and guide clinicians on more targeted interventions to prevent stroke in patients with CKD. This article summarizes the currently available clinical evidence linking covert vascular brain injuries with CKD.

MitoTEMPO protects against podocyte injury by inhibiting NLRP3 inflammasome via PINK1/Parkin pathway-mediated mitophagy

Activation of inflammation is an important pathogenic factor contributing to the development of chronic kidney disease (CKD). Recent studies manifested the implication of impaired mitophagy mediated NLRP3 inflammasome activation in the progression of CKD. Mitochondria-targeted antioxidant mitoTEMPO showed antioxidant and anti-inflammatory properties in kidney disease. This study aims to investigate the protective mechanism of mitoTEMPO on podocyte injury related to mitophagy and NLRP3 inflammasome. Our results showed that mitoTEMPO obviously ameliorated renal function and podocyte injury in CKD model rats induced by cationic bovine serum albumin (C-BSA). More importantly, mitoTMEPO significantly inhibited NLRP3 inflammasome activation compared with CKD model rats (P < 0.01). In vitro, TNF-α damaged human podocyte cells (HPC) and activated NLRP3 inflammasome, which was rescued by NLRP3 inhibitor and mitoTEMPO. Meanwhile, mitoTEMPO lessened excessive mitochondrial ROS (mtROS) and degressive mitochondrial membrane potential (MMP) in HPC. We also found that mitoTEMPO induced mitophagy in vivo and in vitro. Moreover, silenced Parkin dramatically reserved the inhibitory effect of mitoTEMPO on NLRP3 inflammasome. Taking together, these findings reveal that mitoTEMPO ameliorated podocyte injury by inhibiting NLRP3 inflammasome via PINK1/Parkin pathway-mediated mitophagy. MitoTEMPO may be a new candidate to protect against podocyte injury in CKD.

Neurorescuing effect of Cinacalcet against hypercalcemia-induced nerve injury in chronic kidney disease via TRAF2/cIAP1/KLF2/SERPINA3 signal axis.

Hypercalcemia is a common complication in chronic kidney disease (CKD) and unfortunately contributes to nerve injury. This study aims to investigate the potential role and underlying mechanisms of Cinacalcet (CIN) in hypercalcemia-driven nerve injury in CKD. A CKD mouse model was first established by adenine feeding to identify the therapeutic effects of CIN. Molecules related to CIN and CKD were predicted by bioinformatics analysis and their expression in the kidney tissues of CKD mice was measured by immunochemistry. Gain- and loss-of-functions assays were performed both in vitro and in vivo to evaluate their effects on nerve injury in CKD, as reflected by Scr and BUN, and brain calcium content as well as behavior tests. CIN ameliorated hypercalcemia-driven nerve injury in CKD mice. Interactions among TRAF2, an E3-ubiquitin ligase, KLF2, and SERPINA3 were bioinformatically predicted on CIN effect. CIN restricted the ubiquitin-mediated degradation of KLF2 by downregulating TRAF2. KLF2 targeted and inversely regulated SERPINA3 to repress hypercalcemia-driven nerve injury in CKD. CIN was substantiated in vivo to ameliorate hypercalcemia-driven nerve injury in CKD mice through the TRAF2/KLF2/SERPINA3 regulatory axis. Together, CIN suppresses SERPINA3 expression via TRAF2-mediated inhibition of the ubiquitin-dependent degradation of KLF2, thus repressing hypercalcemia-induced nerve injury in CKD mice.