FTO-mediated m6A mRNA demethylation aggravates renal fibrosis by targeting RUNX1 and further enhancing PI3K/AKT pathway.

Chronic kidney disease (CKD) is a global health burden, with ineffective therapies leading to increasing morbidity and mortality. Renal interstitial fibrosis is a common pathway in advanced CKD, resulting in kidney function and structure deterioration. In this study, we investigate the role of FTO-mediated N6-methyladenosine (m6A) and its downstream targets in the pathogenesis of renal fibrosis. M6A modification, a prevalent mRNA internal modification, has been implicated in various organ fibrosis processes. We use a mouse model of unilateral ureteral obstruction (UUO) as an in vivo model and treated tubular epithelial cells (TECs) with transforming growth factor (TGF)-ß1 as in vitro models. Our findings revealed increased FTO expression in UUO mouse model and TGF-ß1-treated TECs. By modulating FTO expression through FTO heterozygous mutation mice (FTO+/- ) in vivo and small interfering RNA (siRNA) in vitro, we observed attenuation of UUO and TGF-ß1-induced epithelial-mesenchymal transition (EMT), as evidenced by decreased fibronectin and N-cadherin accumulation and increased E-cadherin levels. Silencing FTO significantly improved UUO and TGF-ß1-induced inflammation, apoptosis, and inhibition of autophagy. Further transcriptomic assays identified RUNX1 as a downstream candidate target of FTO. Inhibiting FTO was shown to counteract UUO/TGF-ß1-induced RUNX1 elevation in vivo and in vitro. We demonstrated that FTO signaling contributes to the elevation of RUNX1 by demethylating RUNX1 mRNA and improving its stability. Finally, we revealed that the PI3K/AKT pathway may be activated downstream of the FTO/RUNX1 axis in the pathogenesis of renal fibrosis. In conclusion, identifying small-molecule compounds that target this axis could offer promising therapeutic strategies for treating renal fibrosis.

Lipoprotein-associated phospholipase A2 predicts cardiovascular death in patients on maintenance hemodialysis: a 7-year prospective cohort study.

BACKGROUND: Cardiovascular diseases (CVD) is the leading cause of death among maintenance hemodialysis patients, with dyslipidemia being a prevalent complication. The paradoxical relationship between cardiovascular outcomes and established lipid risk markers, such as low-density lipoprotein cholesterol (LDL-C), complicates lipid management in this population. This study investigated Lipoprotein-associated phospholipase A2 (Lp-PLA2), an emerging biomarker known for its proinflammatory and proatherogenic properties, as a potential cardiovascular prognostic marker in this cohort. In this context, the association between Lp-PLA2 levels and cardiovascular outcomes was evaluated, with the aim to facilitate more accurate stratification and identification of high-risk individuals. METHODS: From August 2013 to January 2014, 361 hemodialysis patients were prospectively enrolled. Lp-PLA2 activity and laboratory measures at baseline were quantified. Comorbidities and medications were recorded. All patients were followed until the end of April, 2022. The individual and combined effects of Lp-PLA2 activity and LDL-C on patient outcomes were examined. The association between Lp-PLA2 activity and all-cause mortality, cardiovascular mortality, and major adverse cardiovascular events (MACEs) was analyzed. RESULTS: The median Lp-PLA2 activity was 481.2 U/L. In subjects with Lp-PLA2 activity over 481.2 U/L, significantly higher total cholesterol (4.89 vs. 3.98 mmol/L; P < 0.001), LDL-C (3.06 vs. 2.22 mmol/L; P < 0.001), and apolipoprotein B (0.95 vs. 0.75 mmol/L; P < 0.001) were observed. Over a median follow-up of 78.1 months, 182 patients died, with 77 cases identified as cardiovascular death, 88 MACEs happened. Cardiovascular mortality and MACEs, but not all-cause mortality, were significantly increased in the high Lp-PLA2 group. Cox regression analyses showed that high Lp-PLA2 activity was associated with cardiovascular mortality and MACE occurrence. After comprehensive adjustment, high Lp-PLA2 activity was independently associated with cardiovascular mortality(as a dichotomous variable: HR:2.57, 95%CI:1.58,4.18, P < 0.001; as a continuous variable: HR:1.25, 95%CI:1.10,1.41, P = 0.001) and MACEs(as a dichotomous variable: HR:2.17, 95%CI:1.39,3.40, P = 0.001; as a continuous variable: HR:1.20, 95%CI:1.07,1.36, P = 0.002). When participants were grouped by median Lp-PLA2 activity and LDL-C values, those with high Lp-PLA2 and low LDL-C had the highest CV mortality. The addition of Lp-PLA2 significantly improved reclassification (as a dichotomous variable NRI = 42.51%, 95%CI: 5.0%,61.33%; as a continuous variable, NRI = 33.32%, 95% CI: 7.47%,56.21%). CONCLUSIONS: High Lp-PLA2 activity is an independent risk factor for cardiovascular mortality and MACEs occurrence in patients on hemodialysis. The combined measures of Lp-PLA2 and LDL-C help to identify individuals with a higher risk of cardiovascular death.

DNA binding protein YB-1 is a part of the neutrophil extracellular trap mediation of kidney damage and cross-organ effects.

Open-heart surgery is associated with high morbidity, with acute kidney injury (AKI) being one of the most commonly observed postoperative complications. Following open-heart surgery, in an observational study we found significantly higher numbers of blood neutrophils in a group of 13 patients with AKI compared to 25 patients without AKI (AKI: 12.9±5.4 ×109 cells/L; non-AKI: 10.1±2. 9 ×109 cells/L). Elevated serum levels of neutrophil extracellular trap (NETs) components, such as dsDNA, histone 3, and DNA binding protein Y-box protein (YB)-1, were found within the first 24 hours in patients who later developed AKI. We could demonstrate that NET formation and hypoxia triggered the release of YB-1, which was subsequently shown to act as a mediator of kidney tubular damage. Experimentally, in two models of AKI mimicking kidney hypoperfusion during cardiac surgery (bilateral ischemia/reperfusion (I/R) and systemic lipopolysaccharide (LPS) administration), a neutralizing YB-1 antibody was administered to mice. In both models, prophylactic YB-1 antibody administration significantly reduced the tubular damage (damage score range 1-4, the LPS model: non-specific IgG control, 0.92±0.23; anti-YB-1 0.65±0.18; and in the I/R model: non-specific IgG control 2.42±0.23; anti-YB-1 1.86±0.44). Even in a therapeutic, delayed treatment model, antagonism of YB-1 ameliorated AKI (damage score, non-specific IgG control 3.03±0.31; anti-YB-1 2.58±0.18). Thus, blocking extracellular YB-1 reduced the effects induced by hypoxia and NET formation in the kidney and significantly limited AKI, suggesting that YB-1 is part of the NET formation process and an integral mediator of cross-organ effects.

Emodin Inhibits the Indoxyl Sulfate-Induced trans-Differentiation of Vascular Smooth Muscle Cells through Upregulating Thrombospondin-1.

BACKGROUND: Indoxyl sulfate (IS) is a protein-bound uremic toxin with vascular toxicity. The primary cause of death in uremic patients on maintenance hemodialysis is vascular disease, and it had been reported that vascular smooth muscle cells (VSMCs) trans-differentiation (VT) plays a vital role in the context of vascular diseases, but the underlying mechanisms remain obscure. Thrombospondin-1 (TSP-1) participates in vascular calcification by keeping the balance of extracellular matrix, but its role in IS-induced VT is unclear. METHODS: In this study, clinical specimens, animal models, and in vitro VSMCs were used to investigate the role of TSP-1 in IS induced VT and the potential therapeutic methods. RESULTS: We found that TSP-1 was significantly decreased in arterial samples from uremic patients, animal models, and in VSMCs after IS treatment. Downregulation of TSP-1 sufficiently induced the trans-differentiation genotypes of VSMCs. CONCLUSION: Emodin, the main monomer extracted from rhubarb, could alleviate IS-induced VT in vitro by upregulating TSP-1. Taken together, IS induces VT by downregulating TSP-1. Emodin might be a candidate drug to alleviate VT under IS treatment.

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

OBJECTIVES: 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). METHODS: 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. RESULTS: 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. CONCLUSION: IVIM-DWI and ASL were useful for detecting underlying pathologic injury in early CKD patients with normal eGFR. KEY POINTS: • 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.

Evaluation of interstitial fibrosis in chronic kidney disease by multiparametric functional MRI and histopathologic analysis.

OBJECTIVES: To investigate the diagnostic value of functional MRI to assess renal interstitial fibrosis in patients with chronic kidney disease (CKD). METHODS: We prospectively recruited 80 CKD patients who underwent renal biopsies and 16 healthy volunteers to undergo multiparametric functional MRI examinations. The Oxford MEST-C classification was used to score the interstitial fibrosis. The diagnostic performance of functional MRI to discriminate interstitial fibrosis was evaluated by calculating the area under the receiver operating characteristic (ROC) curves. RESULTS: IgA nephropathy (60%) accounted for the majority of pathologic type in the CKD patients. Apparent diffusion coefficient (ADC) from diffusion-weighted imaging (DWI) was correlated with interstitial fibrosis (rho = -0.73). Decreased renal blood flow (RBF) derived from arterial spin labeling (rho = -0.78) and decreased perfusion fraction (f) derived from DWI (rho = -0.70) were accompanied by increased interstitial fibrosis. The T1 value from T1 mapping correlated with interstitial fibrosis (rho = 0.67) (all p < 0.01). The areas under the ROC curve for the discrimination of ≤ 25% vs. > 25% and ≤ 50% vs. > 50% interstitial fibrosis were 0.87 (95% confidence interval, 0.78 to 0.94) and 0.93 (0.86 to 0.98) by ADC, 0.84 (0.74 to 0.91) and 0.94 (0.86 to 0.98) by f, 0.93 (0.85 to 0.98) and 0.90 (0.82 to 0.96) by RBF, and 0.91 (0.83 to 0.96) and 0.77 (0.66 to 0.85) by T1, respectively. CONCLUSIONS: Functional MRI parameters were strongly correlated with the interstitial fibrosis of CKD. Therefore, it might a powerful tool to assess interstitial fibrosis of CKD noninvasively. KEY POINTS: • In CKD patients, the renal cortical ADC value decreased and T1 value increased significantly compared with healthy volunteers. • Functional MRI revealed significantly decreased renal perfusion in CKD patients compared with healthy volunteers. • The renal cortical ADC, f, RBF, and T1 values were strongly correlated with the interstitial fibrosis of CKD.

Proteinuria is a risk factor for acute kidney injury after cardiac surgery in patients with stages 3-4 chronic kidney disease: a case control study.

BACKGROUND: Acute kidney injury (AKI) is a common complication after cardiac surgery, and preoperative renal dysfunction is an important risk factor. Proteinuria indicates renal structural damage, but there are few studies on proteinuria and the risk of AKI after cardiac surgery in patients with renal dysfunction. This study aimed to elucidate whether proteinuria can predict AKI after cardiac surgery in patients with renal dysfunction. METHODS: Patients with stages 3-4 chronic kidney disease (CKD) who underwent cardiac surgery were included in this retrospective study. AKI was defined according to the KDIGO criteria. The association between proteinuria and AKI in patients with CKD stages 3-4 was investigated. RESULTS: The incidence of AKI in the entire cohort (n = 1546) was 53.55%. The in-hospital mortality of patients with was higher than patients without AKI (AKI vs. no AKI, 4.7 vs. 0.8%, P < 0.001). Multivariate logistic regression analysis showed that proteinuria was an independent risk factor for AKI (trace to 1+ OR 2.37; 2+ -3+ OR 5.16) and AKI requiring renal replacement therapy (AKI-RRT) (trace to 1+ OR 3.64; 2+-3+ OR 5.71). Mild proteinuria (trace to 1+ OR 2.59) was also an independent risk factor for in-hospital death. In patients with diabetes mellitus, mild proteinuria (OR 1.925), instead of severe proteinuria (2-3+), was a risk factor of AKI in patients with kidney dysfunction and diabetes. CONCLUSIONS: In the population of patients with renal dysfunction, the incidence of AKI was high, which significantly compromised renal and overall prognosis. As a simple and inexpensive routine test, preoperative proteinuria still has value in predicting AKI in patients with impaired renal function.

Weekend effect on the incidence and outcomes of cardiac surgery associated - acute kidney injury.

BACKGROUND: The effects of surgical day (workdays or weekends) on occurrence and outcome of cardiac surgery associated -acute kidney injury (CSA-AKI) remains unclear. This study aimed to compare the incidence and short-term outcomes of CSA-AKI in patients undergoing surgery on workdays and weekends. MATERIALS AND METHODS: Patients who underwent cardiac surgery from July 2020 to December 2020 were retrospectively enrolled in this study. These patients were divided into a weekend group and workday group. The primary endpoint was the incidence of CSA-AKI. The secondary endpoints included renal function recovery and in-hospital mortality. The logistic regression model was used to explore the risk factors for CSA-AKI. Stratification analysis was performed to estimate the association between CSA-AKI and weekend surgery stratified by emergency surgery. RESULTS: A total of 1974 patients undergoing cardiac surgery were enrolled. The incidence of CSA-AKI in the weekend group was significantly higher than that in the workday group (42.8% vs. 34.7%, P = 0.038). Further analysis of patients with CSA-AKI showed that there was no difference in renal function recovery between the workday AKI group and weekend AKI group. There was no difference in in-hospital mortality between the weekend group and workday group (3.6% vs. 2.4%, P = 0.327); however, the in-hospital mortality of the weekend AKI group was significantly higher than that of the workday AKI group (8.5% vs. 2.9%, P = 0.014). Weekend surgery and emergency surgery were independent risk factors for CSA-AKI. The multiplicative model showed an interaction between weekend surgery and emergency surgery; weekend surgery was related to an increased risk of AKI among patients undergoing emergency surgery [adjusted OR (95% CI): 1.96 (1.012-8.128)]. CONCLUSIONS: The incidence of CSA-AKI in patients undergoing cardiac surgery on weekends was significantly higher compared to that in patients undergoing cardiac surgery on workdays. Weekend surgery did not affect the in-hospital mortality of all patients but significantly increased the mortality of AKI patients. Weekend surgery and emergency surgery were independent risk factors for CSA-AKI. Weekend emergency surgery significantly increased the risk of CSA-AKI.

Risk Factors and Prognosis of Acute Kidney Injury after Cardiac Surgery in Patients with Chronic Kidney Disease.

INTRODUCTION: Cardiac surgery-associated acute kidney injury (CSA-AKI) is one of the most prevalent complications of cardiac surgery, while the renal and overall prognoses of chronic kidney disease (CKD) patients with CSA-AKI are extremely poor. However, there is little published information on the occurrence of CSA-AKI in patients with CKD. The purpose of this study was to investigate the risk factors and prognostic factors of cardiac surgery-related AKI in patients with CKD. METHODS: A retrospective study was performed on CKD patients who underwent cardiac surgery at a tertiary referral teaching hospital. CSA-AKI was defined based on the KDIGO criteria. The risk factors for CSA-AKI and the factors affecting renal function recovery at discharge or death in patients with AKI were investigated. RESULTS: Among 1638 CKD patients enrolled, the incidence of CSA-AKI was 50.55%. AKI patients' in-hospital mortality was higher than patients without AKI (AKI vs. no AKI, 4.7 vs. 0.9%, p < 0.001). Multivariate logistic regression analysis showed that male (odds ratio [OR] 1.479), preoperative hypertension (OR 1.548), preoperative hemoglobin <110 g/L (OR 2.389), and aortic clamping time >58 min (OR 1.567) were independent risk factors for AKI after cardiac surgery in patients with CKD. Factors affecting renal function recovery of AKI patients included preoperative diabetes mellitus (OR 0.306), hyperchloremia (OR 0.927), estimate of the glomerular filtration rate (OR 1.034), and AKI progression. Compared with patients with AKI stage 1, the rate of renal function recovery in patients with AKI stage 2 and stage 3 was reduced by 78.9% and 82.3%, respectively. CONCLUSIONS: In the population of patients with CKD, the incidence of CSA-AKI was high, which significantly affected renal and overall prognosis. The prompt intervention of modifiable factors may help improve the prognosis of patients with CKD.

Predictive role of cardiac valvular calcification in all-cause mortality of Chinese initial haemodialysis patients: a follow-up study of 4 years.

BACKGROUND: Cardiac valvular calcification (CVC) is prevalent in haemodialysis (HD) patients. Its association with mortality in Chinese incident haemodialysis (IHD) patients remains unknown. METHODS: A total of 224 IHD patients who had just begun HD therapy at Zhongshan Hospital, Fudan University, were enrolled and divided into two groups according to the detection of cardiac valvular calcification (CVC) by echocardiography. The patients were followed for a median of 4 years for all-cause mortality and cardiovascular mortality. RESULTS: During follow-up, 56 (25.0%) patients died, including 29 (51.8%) of cardiovascular disease. The adjusted HR related to all-cause mortality was 2.14 (95% CI, 1.05-4.39) for patients with cardiac valvular calcification. However, CVC was not an independent risk factor for cardiovascular mortality in patients who had just begun HD therapy. CONCLUSION: CVC at baseline is an independent risk factor for all-cause mortality in HD patients and makes an independent contribution to the prediction of all-cause mortality. These findings support the use of echocardiography at the beginning of HD.

The application of new complex indicators in the detection of urine.

BACKGROUND: Accurate diagnosis and assessment of hematuria is crucial for the early detection of chronic kidney disease(CKD). As instability of urinary RBC count (URBC) often results with clinical uncertainty, therefore new urinary indexes are demanded to improve the accuracy of diagnosis of hematuria. In this study, we aimed to investigate the benefit of applying new complex indicators based on random urine red blood cell counts confirmed in hematuric kidney diseases. METHODS: All patients enrolled underwent renal biopsy, and their clinical information was collected. Urinary and blood biomedical indexes were implemented with red blood cell counts to derive complex indicators. Patients were divided into two groups (hematuria-dominant renal histologic lesions and non-hematuria-dominant renal histologic lesions) based on their renal pathological manifestations. The target index was determined by comparing the predictive capabilities of the candidate parameters for hematuric kidney diseases. Hematuria stratification was divided into four categories based on the scale of complex indicators and distributional features. The practicality of the new complex indicators was demonstrated by fitting candidate parameters to models comprising demographic information. RESULTS: A total of 1,066 cases (678 hematuria-dominant renal histologic lesions) were included in this study, with a mean age of 44.9 ± 15 years. In differentiating hematuria-dominant renal histologic lesion from the non-hematuria-dominant renal histologic lesion, the AUC value of "The ratio of the random URBC to 24-h albumin excretion" was 0.76, higher than the standard approach of Lg (URBC) [AUC = 0.744] (95% Confidence interval (CI) 0.712 ~ 0.776). The odds ratio of hematuria-dominant renal histologic lesion (Type I) increased from Q2 (3.81, 95% CI 2.66 ~ 5.50) to Q4 (14.17, 95% CI 9.09 ~ 22.72). The predictive model, composed of stratification of new composite indexes, basic demographic characteristics, and biochemical parameters, performed best with AUC value of 0.869 (95% CI 0.856-0.905). CONCLUSION: The new urinary complex indicators improved the diagnostic accuracy of hematuria and may serve as a useful parameter for screening hematuric kidney diseases.

Effect of angiography timing on acute kidney injury after cardiac surgery in patients with preoperative renal dysfunction.

BACKGROUND: Cardiac surgery-associated acute kidney injury (AKI) is one of the common complications of cardiac surgery. Preoperative angiography helps assess heart disease but may increase the risk of AKI. Although more and more patients with preoperative renal dysfunction can undergo cardiac surgery with the advances in surgical techniques, there is little research on the effect of angiography on postoperative AKI in these patients. This study investigates whether angiography increases the risk of AKI after cardiac surgery in patients with preoperative renal dysfunction (15 ≤ eGFR < 60 ml/min/1.73m2). METHODS: Patients with preoperative renal dysfunction (15 ≤ eGFR < 60 ml/min/1.73m2) who underwent angiography and cardiac surgery successively from January 2015 to December 2020 were retrospectively enrolled in this study. The primary outcome was postoperative AKI, defined as the Kidney Disease: Improving Global Outcomes Definition and Staging (KDIGO) criteria. Univariate analysis and multivariate regression were performed to identify the association between angiography timing and AKI. RESULTS: A total of 888 consecutive eligible patients with preoperative renal dysfunction (15 ≤ eGFR < 60 ml/min/1.73m2) were enrolled in this study. The incidence of AKI was 48.31%. Male (OR = 1.903), the interval between angiography and surgery (0-2d OR = 2.161; 3-6d OR = 3.291), cross-clamp duration (OR = 1.009), were identified as predictors for AKI. The interval between angiography and surgery was also associated with AKI in the patients with 15 ≤ eGFR < 30ml/min/1.73m2 (0-2d OR = 4.826; 3-6d OR = 5.252), 30 ≤ eGFR < 45 ml/min/1.73m2 (0-2d OR = 2.952; 3-6d OR = 3.677), but not associated with AKI in patients with 45 ≤ eGFR < 60 ml/min/1.73m2. CONCLUSIONS: In patients with preoperative renal dysfunction, the interval between angiography and cardiac surgery (0-2d and 3-6d) was associated with AKI. For patients with poorer preoperative renal function, the interval between angiography and cardiac surgery is of great concern.

Urinary N-Acetyl-Beta-D-Glucosaminidase levels predict immunoglobulin a nephropathy remission status.

BACKGROUND: Tubulointerstitial lesions play a pivotal role in the progression of IgA nephropathy (IgAN). Elevated N-acetyl-beta-D-glucosaminidase (NAG) in urine is released from damaged proximal tubular epithelial cells (PTEC) and may serve as a biomarker of renal progression in diseases with tubulointerstitial involvement. METHODS: We evaluated the predictive value of urinary NAG (uNAG) for disease progression in 213 biopsy-proven primary IgAN patients from January 2018 to December 2019 at Zhongshan Hospital, Fudan University. We compared the results with those of serum cystatin C (sCysC). RESULTS: Increased uNAG and sCysC levels were associated with worse clinical and histological manifestations. Only uNAG level was independently associated with remission status after adjustment. Patients with high uNAG levels (> 22.32 U/g Cr) had a 4.32-fold greater risk of disease progression. The combination of baseline uNAG and clinical data may achieve satisfactory risk prediction in IgAN patients with relatively preserved renal function (eGFR ≥ 60 ml/min/1.73 m2, area under the curve [AUC] 0.760). CONCLUSION: Our results suggest that uNAG is a promising biomarker for predicting IgAN remission status.

Risk factor mining and prediction of urine protein progression in chronic kidney disease: a machine learning- based study.

BACKGROUND: Chronic kidney disease (CKD) is a global public health concern. Therefore, to provide timely intervention for non-hospitalized high-risk patients and rationally allocate limited clinical resources is important to mine the key factors when designing a CKD prediction model. METHODS: This study included data from 1,358 patients with CKD pathologically confirmed during the period from December 2017 to September 2020 at Zhongshan Hospital. A CKD prediction interpretation framework based on machine learning was proposed. From among 100 variables, 17 were selected for the model construction through a recursive feature elimination with logistic regression feature screening. Several machine learning classifiers, including extreme gradient boosting, gaussian-based naive bayes, a neural network, ridge regression, and linear model logistic regression (LR), were trained, and an ensemble model was developed to predict 24-hour urine protein. The detailed relationship between the risk of CKD progression and these predictors was determined using a global interpretation. A patient-specific analysis was conducted using a local interpretation. RESULTS: The results showed that LR achieved the best performance, with an area under the curve (AUC) of 0.850 in a single machine learning model. The ensemble model constructed using the voting integration method further improved the AUC to 0.856. The major predictors of moderate-to-severe severity included lower levels of 25-OH-vitamin, albumin, transferrin in males, and higher levels of cystatin C. CONCLUSIONS: Compared with the clinical single kidney function evaluation indicators (eGFR, Scr), the machine learning model proposed in this study improved the prediction accuracy of CKD progression by 17.6% and 24.6%, respectively, and the AUC was improved by 0.250 and 0.236, respectively. Our framework can achieve a good predictive interpretation and provide effective clinical decision support.

Association between gut microbial diversity and technique failure in peritoneal dialysis patients.

BACKGROUND: Gut dysbiosis in peritoneal dialysis (PD) patients causes chronic inflammation and metabolic disorders which result in a series of complications, probably playing an important role in PD technique failure. The reduction in gut microbial diversity was a common feature of gut dysbiosis. The objective was to explore the relationship between gut microbial diversity and technique failure in PD patients. METHODS: The gut microbiota was analyzed by 16s ribosomal RNA gene amplicon sequencing. Cox proportional hazards models were used to identify association between gut microbial diversity and technique failure in PD patients. RESULTS: In this study, a total of 101 PD patients were enrolled. During a median follow-up of 38 months, we found that lower diversity was independently associated with a higher risk of technique failure (hazard ratio [HR], 2.682; 95% confidence interval [CI], 1.319-5.456; p = 0.006). In addition, older age (HR, 1.034; 95% CI, 1.005-1.063; p = 0.020) and the history of diabetes (HR, 5.547; 95% CI, 2.218-13.876; p < 0.001) were also independent predictors for technique failure of PD patients. The prediction model constructed on the basis of three independent risk factors above performed well in predicting technique failure at 36 and 48 months (36 months: area under the curve [AUC] = 0.861; 95% CI, 0.836-0.886; 48 months: AUC = 0.815; 95% CI, 0.774-0.857). CONCLUSION: Gut microbial diversity was independently correlated with technique failure in PD patients, and some specific microbial taxa may serve as a potential therapeutic target for decreasing PD technique failure.

Phosphoproteome Profiling of uEVs Reveals p-AQP2 and p-GSK3ß as Potential Markers for Diabetic Nephropathy.

Diabetic nephropathy (DN) contributes to increased morbidity and mortality among patients with diabetes and presents a considerable global health challenge. However, reliable biomarkers of DN have not yet been established. Phosphorylated proteins are crucial for disease progression. However, their diagnostic potential remains unexplored. In this study, we used ultra-high-sensitivity quantitative phosphoproteomics to identify phosphoproteins in urinary extracellular vesicles (uEVs) as potential biomarkers of DN. We detected 233 phosphopeptides within the uEVs, with 47 phosphoproteins exhibiting significant alterations in patients with DN compared to those in patients with diabetes. From these phosphoproteins, we selected phosphorylated aquaporin-2 (p-AQP2[S256]) and phosphorylated glycogen synthase kinase-3ß (p-GSK3ß[Y216]) for validation, as they were significantly overrepresented in pathway analyses and previously implicated in DN pathogenesis. Both phosphoproteins were successfully confirmed through Phos-tag western blotting in uEVs and immunohistochemistry staining in kidney sections, suggesting that phosphoprotein alterations in uEVs reflect corresponding changes within the kidney and their potential as candidate biomarkers for DN. Our research proposes the utilization of phosphoproteins in uEVs as a liquid biopsy, presenting a highly feasible diagnostic tool for kidney disease.

Chemokine CCL2 from proximal tubular epithelial cells contributes to sepsis-induced acute kidney injury.

Damage-associated molecular patterns secreted from activated kidney cells initiate the inflammatory response, a critical step in the development of sepsis-induced acute kidney injury (AKI). However, the underlying mechanism remains to be clarified. Here, we established a mouse model of sepsis-induced AKI through intraperitoneal injection of lipopolysaccharide (LPS) and demonstrated that LPS induced dramatical upregulation of C-C motif chemokine ligand 2 (CCL2) at both the mRNA and protein levels in the kidney, which was mainly expressed by tubular epithelial cells (TECs), especially by proximal TECs. Proximal tubule-specific ablation of CCL2 reduced LPS-induced macrophage infiltration, proinflammatory cytokine expression, and attenuated AKI. In vitro, using a Transwell migration assay, we found that deficiency of CCL2 in TECs decreased macrophage migration ability. However, myeloid-specific depletion of CCL2 could not protect the kidneys from the aforementioned effects. Mechanistically, LPS activated Toll-like receptor (TLR)2 signaling in TECs, which induced activation of its downstream effector NF-κB. Blockade of TLR2 signaling or inhibition of NF-κB activation in TECs significantly suppressed LPS-induced CCL2 expression. Furthermore, chromatin immunoprecipitation analyses confirmed a direct binding of NF-κB p65 in the CCL2 promoter region, and LPS increased the binding of NF-κB p65 to the CCL2 promoter, suggesting that TLR2/NF-κB p65 regulates CCL2 expression in TECs. Together, these results demonstrate that endogenous CCL2 released from proximal TECs, not from myeloid cells, was responsible for sepsis-induced kidney inflammation and AKI. Specifically targeting tubular TLR2/NF-κB/CCL2 signaling may be a potential therapeutic strategy for the prevention or attenuation of septic AKI.NEW & NOTEWORTHY This study provides a mechanistic insight into how C-C motif chemokine ligand 2 (CCL2) is upregulated in renal tubular epithelial cells (TECs) and contributes to kidney dysfunction during sepsis. The data reveal that lipopolysaccharide induces CCL2 expression through the Toll-like receptor 2/NF-κB signaling pathway in TECs. Endogenous CCL2 released from TECs, not from myeloid cells, is responsible for sepsis-induced kidney inflammation and acute kidney injury.

Blocking ribosomal protein S6 phosphorylation inhibits podocyte hypertrophy and focal segmental glomerulosclerosis.

Ribosomal protein S6 (rpS6) phosphorylation mediates the hypertrophic growth of kidney proximal tubule cells. However, the role of rpS6 phosphorylation in podocyte hypertrophy and podocyte loss during the pathogenesis of focal segmental glomerulosclerosis (FSGS) remains undefined. Here, we examined rpS6 phosphorylation levels in kidney biopsy specimens from patients with FSGS and in podocytes from mouse kidneys with Adriamycin-induced FSGS. Using genetic and pharmacologic approaches in the mouse model of FSGS, we investigated the role of rpS6 phosphorylation in podocyte hypertrophy and loss during development and progression of FSGS. Phosphorylated rpS6 was found to be markedly increased in the podocytes of patients with FSGS and Adriamycin-induced FSGS mice. Genetic deletion of the Tuberous sclerosis 1 gene in kidney glomerular podocytes activated mammalian target of rapamycin complex 1 signaling to rpS6 phosphorylation, resulting in podocyte hypertrophy and pathologic features similar to those of patients with FSGS including podocyte loss, leading to segmental glomerulosclerosis. Since protein phosphatase 1 is known to negatively regulate rpS6 phosphorylation, treatment with an inhibitor increased phospho-rpS6 levels, promoted podocyte hypertrophy and exacerbated formation of FSGS lesions. Importantly, blocking rpS6 phosphorylation (either by generating congenic rpS6 knock-in mice expressing non-phosphorylatable rpS6 or by inhibiting ribosomal protein S6 kinase 1-mediated rpS6 phosphorylation with an inhibitor) significantly blunted podocyte hypertrophy, inhibited podocyte loss, and attenuated formation of FSGS lesions. Thus, our study provides genetic and pharmacologic evidence indicating that specifically targeting rpS6 phosphorylation can attenuate the development of FSGS lesions by inhibiting podocyte hypertrophy and associated podocyte depletion.

Nuclear farnesoid X receptor attenuates acute kidney injury through fatty acid oxidation.

Acute kidney injury (AKI) is a life-threatening condition that is one of most common side effects of cisplatin therapy. Fatty acid oxidation (FAO) is the main source of energy production in kidney proximal tubular epithelial cells (PTECs) but it is inhibited in AKI. Recent work demonstrated that activation of the farnesoid X receptor (FXR) protects against AKI, but the underlying mechanism remains elusive. Using a model of cisplatin-induced AKI, we found that FXR and FAO-related genes were remarkably downregulated while kidney lipid accumulated. Proximal tubule-specific or whole body FXR knockout worsened, while pharmacological activation attenuated these effects. Conversely, FXR knockout in non-proximal tubules did not. RNA-sequencing of PTECs demonstrated increased transcripts involved in metabolic pathways in cells overexpressing FXR versus control after cisplatin treatment, specifically transcripts associated with FAO and peroxisome proliferator-activated receptor-γ (PPARγ) signaling. Furthermore, FXR overexpression or activation improved FAO and inhibited intracellular lipid accumulation in cisplatin-treated cells. In vivo studies have shown that pharmacological activation of PPARγ can prevent cisplatin-induced lipid accumulation, kidney tubule injury and kidney function decline. However, inhibition of PPARγ eliminated the protective effects of FXR compared to control mice during the cisplatin treatment phase and after ischemia-reperfusion injury. Consistent with findings in vivo, FXR/PPARγ reduced lipid accumulation by improving FAO in cisplatin-treated cells. Furthermore, the inhibition of carnitine palmitoyltransferase 1α abolished the protective effect of FXR in cisplatin-treated mice. Thus, FXR improves FAO and reduced lipid accumulation via PPARγ in PTECs of the kidney. Hence, reconstruction of the FXR/PPARγ/FAO axis may be a novel therapeutic strategy for preventing or treating AKI.

The Proportion of Memory CD8+ T Cell Predicts Infection Event in Patients with Peritoneal Dialysis.

INTRODUCTION: The immune senescence marked by the inflation of memory T cell is established in end-stage renal disease (ESRD) patients with peritoneal dialysis (PD). These patients suffer high incidence of infectious disease, which has been relevant to immune dysfunction. However the association of immune senescence with infection in PD patients is not clear. This prospective study aimed to investigate the relationship between proportion of T cell subsets and infection event in patients on PD. METHODS: We enrolled patients on PD >6 months from January 1, 2016 to December 30, 2016 and followed them until April 30, 2020. Baseline T cell subsets from blood were collected at the time of recruitment. The primary end point was infection event including peritonitis, exit site infection, pneumonia, urinary tract infection, and other infection. RESULTS: There were 94 patients (46 male) with a mean age of 56.1 ± 14.9 years old enrolled during the follow-up period, and 26 patients suffered infection events. A higher proportion of effector memory (EM) CD8+ T cells was found in patients with infection than in those without infection. There was no difference in the distribution of EM CD8+ T cells between PD-related and non-dialysis infection. Increased level of EM CD8+ T cells was risk factor for first infection event in PD patients. CONCLUSION: High level of EM CD8+ T cells could be a significant predictor of infection event in patients on PD.