Model Of Chronic Kidney Disease Research Articles

Histone deacetylase 9 promotes osteogenic trans-differentiation of vascular smooth muscle cells via ferroptosis in chronic kidney disease vascular calcification.

Vascular calcification, a common complication of chronic kidney disease (CKD), remains an unmet therapeutic challenge. The trans-differentiation of vascular smooth muscle cells (VSMCs) into osteoblast-like cells is crucial in the pathogenesis of vascular calcification in CKD. Despite ferroptosis promotes vascular calcification in CKD, the upstream or downstream regulatory mechanisms involved remains unclear. In this study, we aimed to investigate the regulatory mechanism involved in ferroptosis in CKD vascular calcification. Transcriptome sequencing revealed a potential relationship between HDAC9 and ferroptosis in CKD vascular calcification. Subsequently, we observed increased expression of HDAC9 in calcified arteries of patients undergoing hemodialysis and in a rat model of CKD. We further demonstrated that knockout of HDAC9 attenuates osteogenic trans-differentiation and ferroptosis in VSMCs stimulated by high calcium and phosphorus. In addition, RSL3 exacerbated ferroptosis and osteogenic trans-differentiation of VSMCs exposed to high levels of calcium and phosphorus, and these effects were suppressed to some extent by HDAC9 knockout. In summary, our findings suggest that HDAC9 promotes VSMCs osteogenic trans-differentiation involving ferroptosis, providing new insights for the therapy of CKD vascular calcification.

Investigating the cause of cardiovascular dysfunction in chronic kidney disease: capillary rarefaction and inflammation may contribute to detrimental cardiovascular outcomes.

Myocardial ischemia-reperfusion (IR) injury is a major cause of morbidity and mortality in patients with chronic kidney disease (CKD). The most frequently used and representative experimental model is the rat dietary adenine-induced CKD, which leads to CKD-associated CVD. However, the continued intake of adenine is a potential confounding factor. This study investigated cardiovascular dysfunction following brief adenine exposure, CKD development and return to a normal diet. Male Wistar rats received a 0.3% adenine diet for 10weeks and normal chow for an additional 8weeks. Kidney function was assessed by urinalysis and histology. Heart function was assessed by echocardiography. Sensitivity to myocardial IR injury was assessed using the isolated perfused rat heart (Langendorff) model. The inflammation profile of rats with CKD was assessed via cytokine ELISA, tissue histology and RNA sequencing. Induction of CKD was confirmed by a significant increase in plasma creatinine and albuminuria. Histology revealed extensive glomerular and tubular damage. Diastolic dysfunction, measured by the reduction of the E/A ratio, was apparent in rats with CKD even following a normal diet. Hearts from rats with CKD had significantly larger infarcts after IR injury. The CKD rats also had statistically higher levels of markers of inflammation including myeloperoxidase, KIM-1 and interleukin-33. RNA sequencing revealed several changes including an increase in inflammatory signaling pathways. In addition, we noted that CKD induced significant cardiac capillary rarefaction. We have established a modified model of adenine-induced CKD, which leads to cardiovascular dysfunction in the absence of adenine. Our observations of capillary rarefaction and inflammation suggest that these may contribute to detrimental cardiovascular outcomes.

Elevation of circulating FGF23 in chronic kidney disease promotes atrial fibrosis through the AKT pathway

Abstract Background The relationship between chronic kidney disease (CKD) and atrial fibrillation (AF) remains unclear. Elevated level of fibroblast growth factor 23 (FGF23) is highly associated with increased cardiovascular disease and mortality in patients suffering from CKD. In recent years, studies have shown that FGF23 promotes cardiac hypertrophy through FGFR4, suggesting that FGF23 may be an important bridge between the heart and kidney. Purpose In this study, we sought to use a well-established rat model of CKD to further characterize the effects of CKD on AF and to identify potential drivers of CKD-induced AF. Methods 14 SD rats were randomly selected to undergo 5/6 nephrectomy and fed for 15 weeks to establish a CKD model, while the SHAM group (8 rats) underwent the same surgery without removing kidney tissue. Body weight, blood pressure, renal function, cardiac ultrasound, epicardial electrocardiography, and pathological indices were monitored in both groups. Gene sequencing was performed on the left atria to search for differentially expressed genes. Rat atrial fibroblasts were selected for further mechanism exploration. We chose TGF-β to stimulate fibroblasts to mimic the process of fibrosis in vivo, and then administered FGFR inhibitors to explore the downstream molecular mechanisms. Results Systolic blood pressure and creatinine were elevated in the CKD group. Compared with the SHAM group, the incidence of AF was significantly higher, left atrial diameter was significantly larger, and epicardial electrical markers showed that left atrial electrical conduction velocity was significantly slower and conduction heterogeneity was significantly increased in the CKD group. Pathologic staining of the left atrium showed significant fibrosis in the CKD group. Consistent with previous findings, FGF23 was significantly elevated in CKD rats. Transcriptomic sequencing revealed that FGFR4 expression was significantly upregulated in the left atrium of CKD rats, The results in rat atrial fibroblasts showed that blocking FGFR4 expression inhibited TGF-β-induced fibrosis and was mediated by the AKT pathway. Conclusions The mechanism of CKD-induced AF is that CKD promotes both structural and electrical remodeling of the atria. Further investigation of its possible downstream molecules revealed that elevated FGF23 in the CKD circulation promotes the development of atrial fibrosis by binding to FGFR4 through the AKT pathway.

Future of Uremic Toxin Management

During the progression of chronic kidney disease (CKD), the retention of uremic toxins plays a key role in the development of uremic syndrome. Knowledge about the nature and biological impact of uremic toxins has grown exponentially over the past decades. However, the science on reducing the concentration and effects of uremic toxins has not advanced in parallel. Additionally, the focus has remained for too long on dialysis strategies, which only benefit the small fraction of people with CKD who suffer from advanced kidney disease, whereas uremic toxicity effects are only partially prevented. This article reviews recent research on alternative methods to counteract uremic toxicity, emphasizing options that are also beneficial in the earlier stages of CKD, with a focus on both established methods and approaches which are still under investigation or at the experimental stage. We will consequently discuss the preservation of kidney function, the prevention of cardiovascular damage, gastro-intestinal interventions, including diet and biotics, and pharmacologic interventions. In the final part, we also review alternative options for extracorporeal uremic toxin removal. The future will reveal which of these options are valid for further development and evidence-based assessment, hopefully leading to a more sustainable treatment model for CKD than the current one.

Increased Susceptibility of Cardiac Tissue to PM2.5-Induced Toxicity in Uremic Cardiomyopathic Rats Is Linked to Elevated Levels of Mitochondrial Dysfunction.

Patients with chronic kidney disease (CKD) frequently develop uremic cardiomyopathy, characterized by mitochondrial dysfunction as one of its pathologically significant mediators. Given that PM2.5 specifically targets cardiac mitochondria, exacerbating toxicity, this study addresses the potential alterations in the severity of PM2.5 toxicity in the context of CKD conditions. Female Wistar rats were exposed to PM2.5 at a concentration of 250 μg/m3 daily for 3 h for 21 days after which an adenine-induced CKD model was developed. While both PM2.5 exposure and the induction of CKD in rats lead to cardiomyopathy, the CKD animals exposed to PM2.5 exhibited a notably severe extent of myocardial hypertrophy and fibrosis. ECG recordings in CKD+ PM2.5 animals revealed a depressed ST segment and prolonged QRS interval, with both PM2.5 and CKD animals displaying an elevated ST segment. Subcellular level analysis confirmed a significantly low mitochondrial copy number and a severe decline in mitochondrial bioenergetic function in the CKD+ PM2.5 group. The prominent decline in PGC1-α further affirmed the severe mitochondrial functional deterioration in CKD+ PM2.5 animals compared to other experimental groups. Additionally, myocardial calcification was enhanced in CKD+ PM2.5 animals, heightening the susceptibility of CKD animals to PM2.5 toxicity. In summary, our findings suggest that the increased vulnerability of CKD myocardium to PM2.5-induced toxicity may be attributed to severe mitochondrial damage and increased calcification in the myocardium.

Propolis Extract Attenuates NF-κB Activation and Chronic Kidney Disease Progression in a Rat Model: Potential Surgical Adjuvant?

Background: Chronic kidney disease (CKD) is a global health concern often complicated by cardiovascular diseases like atherosclerosis. Both conditions share an inflammatory pathogenesis, with nuclear factor kappa B (NF-κB) playing a central role. Propolis, a natural bee product with anti-inflammatory properties, has shown potential in mitigating CKD progression. This study aimed to investigate the effects of propolis extract on NF-κB activation in a rat model of CKD, exploring its potential benefits as a surgical adjuvant. Methods: Male white rats (Rattus norvegicus) were divided into three groups: a control group, a CKD group, and a CKD+Propolis group receiving propolis extract (200 mg/kg body weight) daily for 20 days. CKD was induced using the unilateral ureteral obstruction (UUO) method. NF-κB levels were measured weekly using ELISA. Results: Propolis extract significantly reduced NF-κB levels in the CKD+Propolis group compared to the CKD group (p<0.05). This effect was consistently observed across all time points, indicating a sustained reduction in NF-κB activation with propolis treatment. Conclusion: Propolis extract effectively attenuates NF-κB activation in a rat model of CKD, suggesting its potential as an adjunctive therapy for CKD management, particularly in the context of surgical interventions. Further research is needed to elucidate the underlying mechanisms and evaluate its efficacy in human subjects.

AST-120 Protects Cognitive and Emotional Impairment in Chronic Kidney Disease Induced by 5/6 Nephrectomy

Background: Uremic toxins resulting from chronic kidney disease (CKD) can cause cognitive and emotional disorders, as well as cardiovascular diseases. Indoxyl sulfate (IS) and p-cresol are notable uremic toxins found in patients with CKD. However, few studies have investigated whether reducing uremic toxins can alleviate cognitive and emotional disorders associated with CKD. Methods: We studied the effects of AST-120, which lowers IS levels, through behavioral tests, local field potentials, field excitatory postsynaptic potentials, and histological experiments in a 5/6 nephrectomy CKD model. Results: We confirmed AST-120’s effectiveness in CKD by measuring serum creatinine, blood urea nitrogen, and IS levels and performing renal tissue staining. Behavioral phenotypes indicated an alleviation of cognitive and anxiety disorders following AST-120 treatment in CKD-induced rats, which was further validated through local field potentials and field excitatory postsynaptic potential recordings. Double immunofluorescence staining for aquaporin-4 and glial fibrillary acidic protein in the hippocampus of CKD rats treated with AST-120 showed reduced coexpression. Conclusions: Our findings demonstrate the potential therapeutic effects of AST-120 in lowering IS levels and improving cognitive and emotional impairments associated with CKD.

Fecal bile acid dysmetabolism and reduced ursodeoxycholic acid correlate with novel microbial signatures in feline chronic kidney disease.

Microbial-derived secondary bile acids (SBAs) are reabsorbed and sensed via host receptors modulating cellular inflammation and fibrosis. Feline chronic kidney disease (CKD) occurs with progressive renal inflammation and fibrosis, mirroring the disease pathophysiology of human CKD patients. Prospective cross-sectional study compared healthy cats (n = 6) with CKD (IRIS Stage 2 n = 17, Stage 3 or 4 n = 11). Single timepoint fecal samples from all cats underwent targeted bile acid metabolomics. 16S rRNA gene amplicon sequencing using DADA2 with SILVA taxonomy characterized the fecal microbiota. CKD cats had significantly reduced fecal concentrations (median 12.8 ng/mg, Mann-Whitney p = 0.0127) of the SBA ursodeoxycholic acid (UDCA) compared to healthy cats (median 39.4 ng/mg). Bile acid dysmetabolism characterized by <50% SBAs was present in 8/28 CKD and 0/6 healthy cats. Beta diversity significantly differed between cats with <50% SBAs and > 50% SBAs (PERMANOVA p < 0.0001). Twenty-six amplicon sequence variants (ASVs) with >97% nucleotide identity to Peptacetobacter hiranonis were identified. P. hiranonis combined relative abundance was significantly reduced (median 2.1%) in CKD cats with <50% SBAs compared to CKD cats with >50% SBAs (median 13.9%, adjusted p = 0.0002) and healthy cats with >50% SBAs (median 15.5%, adjusted p = 0.0112). P. hiranonis combined relative abundance was significantly positively correlated with the SBAs deoxycholic acid (Spearman r = 0.5218, adjusted p = 0.0407) and lithocholic acid (Spearman r = 0.5615, adjusted p = 0.0156). Three Oscillospirales ASVs and a Roseburia ASV were also identified as significantly correlated with fecal SBAs. The gut-kidney axis mediated through microbial-derived SBAs appears relevant to the spontaneous animal CKD model of domestic cats. This includes reduced fecal concentrations of the microbial-derived SBA UDCA, known to regulate inflammation and fibrosis and be reno-protective. Microbes correlated with fecal SBAs include bai operon containing P. hiranonis, as well as members of Oscillospirales, which also harbor a functional bai operon. Ultimately, CKD cats represent a translational opportunity to study the role of SBAs in the gut-kidney axis, including the potential to identify novel microbial-directed therapeutics to mitigate CKD pathogenesis in veterinary patients and humans alike.

Benefit of combination therapy with dapagliflozin and eplerenone on cardiac function and fibrosis in rats with non-diabetic chronic kidney disease

Patients with chronic kidney disease (CKD) are at a high risk of cardiovascular (CV) complications. In these patients, sodium-glucose cotransporter-2 inhibitors (SGLT2i) have been shown to reduce CV events. Mineralocorticoid receptor antagonists (MRAs) exert similar benefits in diabetic CKD, though their effects in non-diabetic CKD remain unclear. This study aimed to evaluated whether the combination of Dapagliflozin (DAPA) and Eplerenone (EPLE) would have positive effects on cardiorenal functions in a non-diabetic CKD model. CKD was induced in rats via 5/6 nephrectomy, followed by treatment with DAPA (5 mg/kg/day PO), EPLE (100 mg/kg/day PO) or the combination for 3 months following CKD induction. Cardiorenal functions were assessed after the treatment period. All treated groups showed reduced kidney fibrosis though plasma creatinine and urea levels remained unchanged. Compared to untreated CKD, EPLE or DAPA/EPLE reduced left ventricle (LV) end-diastolic pressure and LV end-diastolic pressure volume relationship, whereas DAPA alone did not achieve significant reductions. Compared to untreated CKD, EPLE and DAPA/EPLE improved cardiac perfusion but DAPA alone did not. Cardiac fibrosis in CKD was blunted by either DAPA or EPLE alone, with the combination showing an additive effect. In conclusion, co-treatment with DAPA and EPLE enhances diastolic function, cardiac perfusion and reduces myocardial fibrosis in non-diabetic CKD rats.

Changes in Skeletal Muscle Atrophy over Time in a Rat Model of Adenine-Induced Chronic Kidney Disease

This study evaluated changes over time in skeletal muscle atrophy, expressions of skeletal muscle anabolic and catabolic genes, and mitochondrial activity by skeletal muscle type in an adenine-induced chronic kidney disease (CKD) model. A CKD model was successfully established by feeding male Wistar rats a 0.75% adenine diet for 4 weeks starting at 8 weeks of age. Control and CKD groups were sacrificed at 12 and 20 weeks of age. The back muscles were analyzed histologically, and succinate dehydrogenase (SDH) staining was performed to evaluate mitochondrial activity. Gene expressions of myogenic determination gene number 1 and myogenin as indicators of muscle anabolism, atrogin-1 and muscle RING-finger protein-1 (MuRF1) as indicators of muscle catabolism, and peroxisome proliferator-activated receptor-γ coactivator-1-α as a marker of mitochondrial biogenesis were assessed. Type I and type II muscle cross-sectional areas (CSAs) were decreased at 12 weeks, but type I muscle CSA was recovered at 20 weeks. SDH staining was lower in CKD than in control rats at 12 weeks, but no significant difference was observed at 20 weeks. Increased expressions of myogenin, atrogin-1, and MuRF-1 were observed only at 12 weeks, but no differences were observed at 20 weeks. The adenine-induced CKD rat model appears to show changes in muscle atrophy over time.

The contribution of the sphingosine 1-phosphate signaling pathway to chronic kidney diseases: recent findings and new perspectives.

Chronic kidney disease (CKD) is a multifactorial condition with diverse etiologies, such as diabetes mellitus, hypertension, and genetic disorders, often culminating in end-stage renal disease (ESRD). A hallmark of CKD progression is kidney fibrosis, characterized by the excessive accumulation of extracellular matrix components, for which there is currently no effective anti-fibrotic therapy. Recent literature highlights the critical role of sphingosine 1-phosphate (S1P) signaling in CKD pathogenesis and renal fibrosis. This review provides an in-depth analysis of the latest findings on S1P metabolism and signaling in renal fibrosis and in specific CKDs, including diabetic nephropathy (DN), lupus nephritis (LN), focal segmental glomerulosclerosis (FSGS), Fabry disease (FD), and IgA nephropathy (IgAN). Emerging studies underscore the therapeutic potential of modulating S1P signaling with receptor modulators and inhibitors, such as fingolimod (FTY720) and more selective agents like ozanimod and cenerimod. Additionally, the current knowledge about the effects of established kidney protective therapies such as glucocorticoids and SGLT2 and ACE inhibitors on S1P signaling will be summarized. Furthermore, the review highlights the potential role of S1P as a biomarker for disease progression in CKD models, particularly in Fabry disease and diabetic nephropathy. Advanced technologies, including spatial transcriptomics, are further refining our understanding of S1P's role within specific kidney compartments. Collectively, these insights emphasize the need for continued research into S1P signaling pathways as promising targets for CKD treatment strategies.

VCAM-1 mediates proximal tubule-immune cell cross talk in failed tubule recovery during AKI-to-CKD transition.

Studies in animal models have suggested a linkage between the inflammatory response to injury and subsequent nephron loss during the acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Failure of normal repair during the CKD transition correlates with de novo expression of vascular cell adhesion protein-1 (VCAM-1) by a subset of injured proximal tubule cells. This study identified the role of VCAM-1 expression in promoting the failed repair state. Single-cell transcriptome analysis of patients with AKI and CKD and whole kidney RNA and protein analyses of mouse models of CKD confirmed a marked increase of VCAM-1 expression in the proximal tubules of injured kidneys. In immortalized mouse proximal tubular cells and primary cultured renal cells (PCRCs), VCAM-1 expression was induced by proinflammatory cytokines including tumor necrosis factor (TNF)-α and interleukin (IL)-1β. Analyses of bulk RNA sequencing of TNF-α-treated primary cultured renal cells or pseudo-bulk RNA sequencing of biopsies from Kidney Precision Medicine Project datasets indicated activation of NF-κB and an enrichment of inflammatory response and cell adhesion pathways in VCAM-1-positive cells. Pharmacological inhibition of NF-κB signaling or genetic deletion of myeloid differentiation factor 88 and TIR domain-containing adapter-inducing interferon-β suppressed TNF-α- and IL-1β-induced VCAM-1 expression in vitro. TNF-α stimulation or overexpression of VCAM-1 significantly increased splenocyte adhesion to the mouse proximal tubular monolayer in culture. These results demonstrate that persistence of proinflammatory cytokines after AKI can induce NF-κB-dependent VCAM-1 expression by proximal tubule cells, mediating increased immune cell adhesion to the tubule and thus promoting further tubule injury and greater risk of progression from AKI to CKD.NEW & NOTEWORTHY We demonstrated the induction of VCAM-1 and its biological function in proximal tubules. We found that proinflammatory cytokines (TNF-α and IL-1β) significantly induced VCAM-1 expression via NF-κB signaling pathway. TNF-α treatment or overexpression of VCAM-1 in immortalized MPT cells increased CD45+ splenocyte adhesion. Pharmacological inhibition of NF-κB or genetic deletion of Vcam1 suppressed TNF-α-induced splenocyte adhesion in vitro, suggesting that VCAM-1 mediates proximal tubular-immune cell cross talk in failed tubule recovery during AKI-to-CKD transition.

Projecting the Population Level Burden of CKD Progression According to Urine Albumin-to-Creatinine Ratio Categories

IntroductionUrinary albumin-creatinine ratio (uACR) is an independent predictor of chronic kidney disease (CKD) progression, however there is limited evidence on the burden of CKD according to uACR categories at a population level. This study estimates future clinical and financial burden of CKD according to uACR categories using the Inside CKD microsimulation. MethodsThe Inside CKD model is an individual patient level microsimulation that emulates national populations based on demographic, epidemiological and economic data. The analysis estimates clinical and economic outcomes over time according to KDIGO uACR categories (A1–A3) at a population level for 31 countries and regions. ResultsCKD populations (diagnosed and undiagnosed individuals, stages G3-5) were projected to be predominantly within uACR categories A1 and A2 in 2022. Projected cumulative incidence of CKD stage transitions (disease progression) and cardio-renal complications (heart failure, myocardial infarction, stroke, and all-cause mortality) occurred mostly in uACR categories A1 and A2 between 2022–2027. Patients in uACR categories A1 and A2, who represent the largest proportion of patients with CKD, were projected to incur most of the healthcare costs associated with CKD management and cardio-renal complications for the diagnosed population (prevalence 2027). ConclusionThis study highlights the disproportionate population-level clinical and economic burden associated with individuals within KDIGO uACR categories A1 and A2, who represent most of the CKD population. This awareness will help healthcare decision makers to appropriately allocate resource and interventions to the CKD population, including those with mildly to moderately increased albuminuria, to reduce clinical and economic burden associated with CKD.

Personalized Prediction of Long-Term Renal Function Prognosis Following Nephrectomy Using Interpretable Machine Learning Algorithms: Case-Control Study.

Acute kidney injury (AKI) is a common adverse outcome following nephrectomy. The progression from AKI to acute kidney disease (AKD) and subsequently to chronic kidney disease (CKD) remains a concern; yet, the predictive mechanisms for these transitions are not fully understood. Interpretable machine learning (ML) models offer insights into how clinical features influence long-term renal function outcomes after nephrectomy, providing a more precise framework for identifying patients at risk and supporting improved clinical decision-making processes. This study aimed to (1) evaluate postnephrectomy rates of AKI, AKD, and CKD, analyzing long-term renal outcomes along different trajectories; (2) interpret AKD and CKD models using Shapley Additive Explanations values and Local Interpretable Model-Agnostic Explanations algorithm; and (3) develop a web-based tool for estimating AKD or CKD risk after nephrectomy. We conducted a retrospective cohort study involving patients who underwent nephrectomy between July 2012 and June 2019. Patient data were randomly split into training, validation, and test sets, maintaining a ratio of 76.5:8.5:15. Eight ML algorithms were used to construct predictive models for postoperative AKD and CKD. The performance of the best-performing models was assessed using various metrics. We used various Shapley Additive Explanations plots and Local Interpretable Model-Agnostic Explanations bar plots to interpret the model and generated directed acyclic graphs to explore the potential causal relationships between features. Additionally, we developed a web-based prediction tool using the top 10 features for AKD prediction and the top 5 features for CKD prediction. The study cohort comprised 1559 patients. Incidence rates for AKI, AKD, and CKD were 21.7% (n=330), 15.3% (n=238), and 10.6% (n=165), respectively. Among the evaluated ML models, the Light Gradient-Boosting Machine (LightGBM) model demonstrated superior performance, with an area under the receiver operating characteristic curve of 0.97 for AKD prediction and 0.96 for CKD prediction. Performance metrics and plots highlighted the model's competence in discrimination, calibration, and clinical applicability. Operative duration, hemoglobin, blood loss, urine protein, and hematocrit were identified as the top 5 features associated with predicted AKD. Baseline estimated glomerular filtration rate, pathology, trajectories of renal function, age, and total bilirubin were the top 5 features associated with predicted CKD. Additionally, we developed a web application using the LightGBM model to estimate AKD and CKD risks. An interpretable ML model effectively elucidated its decision-making process in identifying patients at risk of AKD and CKD following nephrectomy by enumerating critical features. The web-based calculator, found on the LightGBM model, can assist in formulating more personalized and evidence-based clinical strategies.

Imperatorin ameliorates ferroptotic cell death, inflammation, and renal fibrosis in a unilateral ureteral obstruction mouse model

BackgroundImperatorin is a naturally occurring furocoumarin derivative found in traditional Chinese medicine Angelica dahurica for its anticancer, antihypertensive, and antidiabetic properties. Chronic kidney disease (CKD) is a global health issue, characterized by a high prevalence, significant morbidity and mortality, and a range of related complications. ObjectiveThis study aims to investigate the protective effects of imperatorin treatment and the specific underlying mechanisms in progressive CKD. MethodsImperatorin was orally administrated for 14 consecutive days to mice with unilateral ureteral obstruction (UUO) to investigate the renal pathological alternations, pro-inflammatory mediators, antioxidant response, and ferroptotic death signaling. Imperatorin was also tested in the erastin-induced injury of renal proximal tubular cells (NRK-52E). Cell viability, ferroptosis protein markers, erastin-induced oxidative stress, and lipid peroxidation were assessed. ResultsIn vivo, imperatorin treatment alleviated kidney histology alternations and attenuated the protein expression of fibrotic markers. Furthermore, imperatorin administration reduced inflammatory cell infiltration, and alleviated the oxidative stress burden by downregulating protein markers such as catalase, superoxide dismutase 2 (SOD-2), NADPH oxidase 4 (NOX-4), and thioredoxin reductase 1 (Trxr-1). It also mitigated ferroptosis markers such as glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11/cystine transporter (SLC7A11/xCT), and transferrin receptor 1 (TFR-1), and attenuated renal cell apoptosis. In vitro, imperatorin treatment effectively decreased erastin-induced feroptotic cell death, restored the antioxidant enzyme levels, and mitigated lipid peroxidation as well as the expression of ferroptosis-related markers (XCT, GPX4, and p-p53) in a dose-dependent manner. ConclusionOur finding demonstrated for the first time, that imperatorin treatment holds therapeutic potential in a UUO mouse model of CKD and inhibits the erastin-induced oxidative stress, ferroptosis, and subsequent lipid peroxidation in vitro. This highlights the potential of imperatorin as a future therapeutic target for ferroptosis to improve the progression of CKD.

Irisin Ameliorates Muscle Atrophy by Inhibiting the Upregulation of the Ubiquitin‒Proteasome System in Chronic Kidney Disease.

Muscle atrophy is a common complication of chronic kidney disease (CKD). Irisin, a novel muscle cytokine, protects against muscle atrophy, but its specific role in CKD-associated muscle atrophy requires further elucidation. Because the ubiquitin-proteasome system (UPS) plays an important role in CKD muscle atrophy, our study will explore whether irisin affects UPS and alleviate CKD-associated muscle atrophy. In this study, an adenine-fed mouse model of CKD and urotension II (UII)-induced C2C12 myotubes were used as in vivo and in vitro models of muscle atrophy. The results showed that renal function, mouse weight, and the cross-sectional area (CSA) of skeletal muscles were significantly improved in CKD mice treated with irisin. Moreover, irisin effectively mitigated the decreases in phosphorylated Forkhead box O 3a (p-FOXO3A) levels and increases in the levels of E3 ubiquitin ligases, such as muscle RING finger 1 (MuRF1) and muscle atrophy F-box (MAFbx/atrogin1), in both the muscles of CKD mice and UII-induced C2C12 myotubes. In addition, irisin significantly increased the expression levels of myogenic differentiation factor D (MyoD) in the muscles of CKD mice. Our study is the first to demonstrate that irisin ameliorates skeletal muscle atrophy by inhibiting UPS upregulation and improving satellite cell differentiation in CKD.

A PDE1 inhibitor, vinpocetine, ameliorates epithelial-mesenchymal transition and renal fibrosis in adenine-induced chronic kidney injury in rats by targeting the DNMT1/Klotho/β-catenin/Snail 1 and MMP-7 pathways.

Tubulointerstitial fibrosis (TIF) is present with chronic kidney disease (CKD). Vinpocetine (Vinpo) is used for treating cerebrovascular deficits, exhibiting some kidney-beneficial effects; however, its role in TIF is uncertain. So, the aim of this study was to investigate its potential impact on adenine-induced fibrotic CKD and explore the underlying mechanistic aspects. Eighteen male Wistar rats were categorized into three groups (n = 6 each). Group I was kept as controls and given saline; group II received adenine (300 mg/kg, twice weekly, i.p.) for induction of the CKD model; and group III was administered Vinpo (20 mg/kg/d, orally) concurrently with adenine. All treatments were administered for 4 weeks. Vinpo revealed an improvement in renal function and an alleviation of inflammation triggered by adenine via diminishing serum tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) levels. Further, Vinpo repressed the epithelial-mesenchymal transition (EMT) with preserved E-cadherin mRNA expression and lowered gene and immune expression of fibronectin and vimentin, respectively, besides attenuating the elevated G2/M arrest-related molecules (renal Ki67 protein contents and p21 gene expression). Renal pathological alterations caused by adenine were attenuated upon Vinpo administration. Interestingly, Vinpo suppressed abnormal renal β-catenin immunoreactivity, Snail 1, and MMP-7 gene expression while simultaneously restored Klotho protein expression by downregulating DNA methyltransferase 1 enzyme (DNMT1) protein expression in the kidney. These data indicated that Vinpo effectively mitigated EMT and G2/M arrest-induced renal fibrosis in adenine-induced CKD rats by targeting DNMT1-associated Klotho suppression, subsequently inhibiting β-catenin and its fibrotic downstream genes.

Interleukin‐6 induces cognitive impairment via toll‐like receptor 4 (TLR4)‐mediated neuroinflammation and neurodegeneration in mice with chronic kidney disease

AbstractBackgroundsPast epidemiological and experimental studies in rodents have demonstrated that chronic kidney disease (CKD) leads to cognitive impairment. However, the underlying mechanism requires further investigation. Herein, a mouse model of CKD was established using conventional 5/6 nephrectomy. We aimed to examine the relationship between CKD and cognitive impairment and elucidate the underlying mechanisms.MethodsCognitive behavior was assessed using the Morris water maze, novel object recognition test, and fear conditioning test. Further experiments were also conducted to investigate the underlying molecular mechanisms.ResultsOur clinical data revealed a decrease in cognitive function among patients with CKD, accompanied by elevated plasma levels of pro‐inflammatory cytokines. A positive correlation between cytokine concentrations and serum creatinine levels, as well as a significant positive correlation with cognitive dysfunction, were observed. Correlation analyzes demonstrated that hippocampal cytokine levels were positively correlated with serum creatinine levels and cognitive dysfunction in CKD model mice. Furthermore, 20 mg/mL interleukin‐6 (IL‐6) significantly decreased HT22 cell activity in vitro. Further, HT22 cells treated with IL‐6 showed increased expression levels of toll‐like receptor 4 (TLR4) and myeloid differentiation primary response gene 88 (MyD88), thereby inducing the nuclear factor kappa‐B p65 inflammatory pathway and mitochondria‐dependent apoptosis. The CKD mouse model showed increased expression of TLR4 and cytokines in the hippocampus. TLR4 knockdown antagonized the IL‐6‐mediated pro‐inflammatory and pro‐apoptotic effects in HT22 cells. TLR4 knockdown in the CKD model mice decreased hippocampal inflammation and increased the number of neuron dendrites, thus ameliorated cognitive impairment.ConclusionThese results suggest that IL‐6 triggers TLR4 activation to induce neuroinflammation and neurodegeneration in CKD, ultimately culminate in cognitive impairment.

Identifying biochemical changes in the kidney using proton nuclear magnetic resonance in an adenine diet chronic kidney disease mouse model.

This study aimed to investigate the metabolic changes in the kidneys in a murine adenine-diet model of chronic kidney disease (CKD). Kidney fibrosis is the common pathological manifestation across CKD aetiologies. Sustained inflammation and fibrosis cause changes in preferred energy metabolic pathways in the cells of the kidney. Kidney cortical tissue from mice receiving a control or adenine-supplemented diet for 8weeks (late inflammation and fibrosis) and 12 weeks (8weeks of treatment followed by 4weeks recovery) were analysed by 2D-correlated nuclear magnetic resonance spectroscopy and compared with histopathology and biomarkers of kidney damage. Tissue metabolite and lipid levels were assessed using the MestreNova software. Expression of genes related to inflammation, fibrosis, and metabolism were measured using quantitative polymerase chain reaction. Animals showed indicators of severely impaired kidney function at 8 and 12 weeks. Significantly increased fibrosis was present at 8weeks but not in the recovery group suggesting some reversal of fibrosis and amelioration of inflammation. At 8weeks, metabolites associated with glycolysis were increased, while lipid signatures were decreased. Genes involved in fatty acid oxidation were decreased at 8weeks but not 12 weeks while genes associated with glycolysis were significantly increased at 8weeks but not at 12 weeks. In this murine model of CKD, kidney fibrosis was associated with the accumulation of triglyceride and free lactate. There was an up-regulation of glycolytic enzymes and down-regulation of lipolytic enzymes. These metabolic changes reflect the energy demands associated with progressive kidney disease where there is a switch from fatty acid oxidation to that of glycolysis.

Activation of Yes-Associated Protein Is Indispensable for Transformation of Kidney Fibroblasts into Myofibroblasts during Repeated Administration of Cisplatin.

Cisplatin is a potent chemotherapy medication that is used to treat various types of cancer. However, it can cause nephrotoxic side effects, which lead to acute kidney injury (AKI) and subsequent chronic kidney disease (CKD). Although a clinically relevant in vitro model of CKD induced by repeated administration of low-dose cisplatin (RAC) has been established, its underlying mechanisms remain poorly understood. Here, we compared single administration of high-dose cisplatin (SAC) to repeated administration of low-dose cisplatin (RAC) in myofibroblast transformation and cellular morphology in a normal rat kidney fibroblast NRK-49F cell line. RAC instead of SAC transformed the fibroblasts into myofibroblasts as determined by α-smooth muscle actin, enlarged cell size as represented by F-actin staining, and increased cell flattening as expressed by the semidiameter ratio of attached cells to floated cells. Those phenomena, as well as cellular senescence, were significantly detected from the time right before the second administration of cisplatin. Interestingly, inhibition of the interaction between Yes-associated protein (YAP) and the transcriptional enhanced associated domain (TEAD) using Verteporfin remarkedly reduced cell size, cellular senescence, and myofibroblast transformation during RAC. These findings collectively suggest that YAP activation is indispensable for cellular hypertrophy, senescence, and myofibroblast transformation during RAC in kidney fibroblasts.