Glycolysis in Peritubular Endothelial Cells and Microvascular Rarefaction in CKD.

BACKGROUND: Peritubular endothelial cell dropout leading to microvascular rarefaction is a common manifestation of chronic kidney disease (CKD). The role of metabolism reprogramming in peritubular endothelial cell loss in CKD is undetermined. METHODS: Single-cell sequencing and metabolic analysis were used to characterize metabolic profile of peritubular endothelial cells from CKD patients and from CKD mouse models. In vivo and in vitro models demonstrated metabolic reprogramming in peritubular endothelial cells in conditions of CKD and its contribution to microvascular rarefaction. RESULTS: Here, we identified glycolysis as a top dysregulated metabolic pathway in peritubular endothelial cells from CKD patients. Specifically, CKD peritubular endothelial cells were hypoglycolytic while displaying an anti-angiogenic response with decreased proliferation and increased apoptosis. The hypoglycolytic phenotype of peritubular endothelial cells was recapitulated in CKD mouse models and in peritubular endothelial cells stimulated by hydrogen peroxide (H2O2). Mechanically, oxidative stress, through activating a redox sensor kruppel-like transcription factor 9, downregulated the glycolytic activator 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase (PFKFB3) expression, thereby reprogramming peritubular endothelial cells towards a hypoglycolytic phenotype. PFKFB3 overexpression in peritubular endothelial cells restored H2O2-induced reduction in glycolysis and cellular ATP levels, and enhanced the G1/S cell cycle transition, enabling peritubular endothelial cells to improve proliferation and reduce apoptosis. Consistently, restoration of peritubular endothelial cell glycolysis in CKD mice, via overexpressing endothelial Pfkfb3, reversed the anti-angiogenic response in peritubular endothelial cells and protected the kidney from microvascular rarefaction and fibrosis. In contrast, suppression of glycolysis by endothelial Pfkfb3 deletion exacerbated microvascular rarefaction and fibrosis in CKD mice. CONCLUSIONS: Our study revealed a disrupted regulation of glycolysis in peritubular endothelial cells as an initiator of microvascular rarefaction in CKD. Restoration of peritubular endothelial cell glycolysis in CKD kidney improved microvascular rarefaction and ameliorated fibrotic lesions.

Kidney function-specific cut-off values of high-sensitivity cardiac troponin T for the diagnosis of acute myocardial infarction.

Background: The diagnosis of acute myocardial infarction (AMI) using high-sensitivity cardiac troponin T (hs-cTnT) remains challenging in patients with kidney dysfunction. Methods: In this large, multicenter cohort study, a total of 20 912 adults who underwent coronary angiography were included. Kidney function-specific cut-off values of hs-cTnT were determined to improve the specificity without sacrificing sensitivity, as compared with that using traditional cut-off value (14 ng/L) in the normal kidney function group. The diagnostic accuracy of the novel cut-off values was validated in an independent validation cohort. Results: In the derivation cohort (n = 12 900), 3247 patients had an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. Even in the absence of AMI, 50.2% of participants with eGFR <60 mL/min/1.73 m2 had a hs-cTnT concentration ≥14 ng/L. Using 14 ng/L as the threshold of hs-cTnT for diagnosing AMI led to a significantly reduced specificity and positive predictive value in patients with kidney dysfunction, as compared with that in patients with normal kidney function. The kidney function-specific cut-off values were determined as 14, 18 and 48 ng/L for patients with eGFR >60, 60-30 and <30 mL/min/1.73 m2, respectively. Using the novel cut-off values, the specificities for diagnosing AMI in participants with different levels of kidney dysfunction were remarkably improved (from 9.1%-52.7% to 52.8-63.0%), without compromising sensitivity (96.6%-97.9%). Similar improvement of diagnostic accuracy was observed in the validation cohort (n = 8012). Conclusions: The kidney function-specific cut-off values of hs-cTnT may help clinicians to accurately diagnose AMI in patients with kidney dysfunction and avoid the potential overtreatment in practice.

Omega-3 PUFAs slow organ aging through promoting energy metabolism.

Energy metabolism disorder, mainly exhibiting the inhibition of fatty acid degradation and lipid accumulation, is highly related with aging acceleration. However, the intervention measures are deficient. Here, we reported Omega-3 polyunsaturated fatty acids (Omega-3 PUFAs), especially EPA, exerted beneficial effects on maintaining energy metabolism and lipid homeostasis to slow organ aging. As the endogenous agonist of peroxisome proliferator-activated receptor α (PPARα), Omega-3 PUFAs significantly boosted fatty acid ß-oxidation and ATP production in multiple aged organs. Consequently, Omega-3 PUFAs effectively inhibited age-related pathological changes, preserved organ function, and retarded aging process. The beneficial effects of Omega-3 PUFAs were also testified in mfat-1 transgenic mice, which spontaneously generate abundant endogenous Omega-3 PUFAs. In conclusion, our study innovatively demonstrated Omega-3 PUFAs administration in diet slow aging through promoting energy metabolism. The supplement of Omega-3 PUFAs or fat-1 transgene provides a promising therapeutic approach to promote healthy aging in the elderly.

Association of accelerometer-derived "weekend warrior" moderate to vigorous physical activity, chronic kidney disease and acute kidney injury.

OBJECTIVE: To examine the relationship between an accelerometer-derived "weekend warrior" pattern, characterized by achieving the most moderate to vigorous physical activity (MVPA) over 1-2 days, as opposed to more evenly distributed patterns, with risk of chronic kidney disease (CKD) and acute kidney injury (AKI). METHODS: 77,977 participants without prior kidney diseases and with usable accelerometer data (collected between 2013 and 2015) were included from the UK Biobank. Three physical activity patterns were compared: active weekend warrior pattern (achieving ≥150 min MVPA per week and accumulating ≥50 % of total MVPA in 1-2 days), active regular pattern (achieving ≥150 min MVPA but not meeting active weekend warrior criteria per week), and inactive pattern (<150 min MVPA per week). The study outcomes included incident CKD and AKI, ascertained through self-report data and data linkage with primary care, hospital admissions, and death registry records. RESULTS: During a median follow-up of 6.8 years, 1324 participants developed CKD and 1515 developed AKI. In multivariable-adjusted models, when compared with inactive participants, individuals with active weekend warrior pattern (CKD: hazard ratio [HR], 0.79, 95 % confidence interval [CI], 0.69-0.89; AKI: HR, 0.70, 95 %CI, 0.62-0.79) and those with active regular pattern (CKD: HR, 0.81, 95 %CI, 0.69-0.95; AKI: HR, 0.79, 95 %CI, 0.68-0.91) exhibited a similar and significantly lower risk of incident CKD and AKI. Similar findings were observed at the median threshold of ≥230.4 min of MVPA per week. CONCLUSION: Concentrated MVPA within 1 to 2 days is as effective as distributed ones in decreasing the risk of renal outcomes.

Cannabinoid receptor 2 plays a key role in renal fibrosis through inhibiting lipid metabolism in renal tubular cells.

AIMS: Renal fibrosis is a common feature in various chronic kidney diseases (CKD). Tubular cell damage is a main characterization which results from dysregulated fatty acid oxidation (FAO) and lipid accumulation. Cannabinoid Receptor 2 (CB2) contributes to renal fibrosis, however, its role in FAO dysregulation in tubular cells is not clarified. In this study, we found CB2 plays a detrimental role in lipid metabolism in tubular cells. METHODS: CB2 knockout mice were adopted to establish a folic acid-induced nephropathy (FAN) model. CB2-induced FAO dysfunction, lipid deposition, and fibrogenesis were assessed in vivo and vitro. To explore molecular mechanisms, ß-catenin inhibitors and peroxisome proliferator-activated receptor alpha (PPARα) activators were also used in CB2-overexpressed cells. The mediative role of ß-catenin in CB2-inhibited PPARα and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) activation was analyzed. RESULTS: CB2 activates ß-catenin signaling, resulting in the suppression of PPARα/PGC-1α axis. This decreased FAO functions and led to lipid droplet formation in tubular cells. CB2 gene ablation effectively mitigated FAO dysfunction, lipid deposition and uremic toxins accumulation in FAN mice, consequently retarding renal fibrosis. Additionally, inhibition to ß-catenin or PPARα activation could greatly inhibit lipid accumulation and fibrogenesis induced by CB2. CONCLUSIONS: This study highlights CB2 disrupts FAO in tubular cells through ß-catenin activation and subsequent inhibition on PPARα/PGC-1α activity. Targeted inhibition on CB2 offers a perspective therapeutic strategy to fight against renal fibrosis.

Inverse association between serum chloride levels and the risk of atrial fibrillation in chronic kidney disease patients.

Background: Electrolyte abnormalities are common symptoms of chronic kidney disease (CKD), but previous studies have mainly focussed on serum potassium and sodium levels. Chloride is an important biomarker for the prognosis of various diseases. However, the relationship between serum chloride levels and atrial fibrillation (AF) in CKD patients is unclear. Objective: In this study, we sought to determine the association between serum chloride homeostasis and AF in CKD patients. Methods: In this retrospective cohort study, we included patients who met the diagnostic criteria for CKD in China between 2000 and 2021. Competing risk regression for AF was performed. The associations of the baseline serum chloride concentration with heart failure (HF) and stroke incidence were also calculated by competing risk regression. The association of baseline serum chloride levels with all-cause death was determined by a Cox regression model. Results: The study cohort comprised 20 550 participants. During a median follow-up of 350 days (interquartile range, 123-730 days), 211 of the 20 550 CKD patients developed AF. After multivariable adjustment, every decrease in the standard deviation of serum chloride (5.02 mmol/l) was associated with a high risk for AF [sub-hazard ratio (sHR) 0.78, 95% confidence interval (CI) 0.65-0.94, P = .008]. These results were also consistent with those of the stratified and sensitivity analyses. According to the fully adjusted models, the serum chloride concentration was also associated with a high risk for incident HF (sHR 0.85, 95% CI 0.80-0.91, P < .001), a high risk for incident stroke (sHR 0.87, 95% CI 0.81-0.94, P < .001), and a high risk for all-cause death [hazard ratio (HR) 0.82, 95% CI 0.73-0.91, P < .001]. Conclusion: In this CKD population, serum chloride levels were independently and inversely associated with the incidence of AF. Lower serum chloride levels were also associated with an increased risk of incident HF, stroke, and all-cause death.

Angiotensin-Converting Enzyme Inhibitors or Angiotensin-Receptor Blockers for Advanced Chronic Kidney Disease : A Systematic Review and Retrospective Individual Participant-Level Meta-analysis of Clinical Trials.

BACKGROUND: In patients with advanced chronic kidney disease (CKD), the effects of initiating treatment with an angiotensin-converting enzyme inhibitor (ACEi) or angiotensin-receptor blocker (ARB) on the risk for kidney failure with replacement therapy (KFRT) and death remain unclear. PURPOSE: To examine the association of ACEi or ARB treatment initiation, relative to a non-ACEi or ARB comparator, with rates of KFRT and death. DATA SOURCES: Ovid Medline and the Chronic Kidney Disease Epidemiology Collaboration Clinical Trials Consortium from 1946 through 31 December 2023. STUDY SELECTION: Completed randomized controlled trials testing either an ACEi or an ARB versus a comparator (placebo or antihypertensive drugs other than ACEi or ARB) that included patients with a baseline estimated glomerular filtration rate (eGFR) below 30 mL/min/1.73 m2. DATA EXTRACTION: The primary outcome was KFRT, and the secondary outcome was death before KFRT. Analyses were done using Cox proportional hazards models according to the intention-to-treat principle. Prespecified subgroup analyses were done according to baseline age (<65 vs. ≥65 years), eGFR (<20 vs. ≥20 mL/min/1.73 m2), albuminuria (urine albumin-creatinine ratio <300 vs. ≥300 mg/g), and history of diabetes. DATA SYNTHESIS: A total of 1739 participants from 18 trials were included, with a mean age of 54.9 years and mean eGFR of 22.2 mL/min/1.73 m2, of whom 624 (35.9%) developed KFRT and 133 (7.6%) died during a median follow-up of 34 months (IQR, 19 to 40 months). Overall, ACEi or ARB treatment initiation led to lower risk for KFRT (adjusted hazard ratio, 0.66 [95% CI, 0.55 to 0.79]) but not death (hazard ratio, 0.86 [CI, 0.58 to 1.28]). There was no statistically significant interaction between ACEi or ARB treatment and age, eGFR, albuminuria, or diabetes (P for interaction > 0.05 for all). LIMITATION: Individual participant-level data for hyperkalemia or acute kidney injury were not available. CONCLUSION: Initiation of ACEi or ARB therapy protects against KFRT, but not death, in people with advanced CKD. PRIMARY FUNDING SOURCE: National Institutes of Health. (PROSPERO: CRD42022307589).

Large-Scale Proteomics Improve Prediction of Chronic Kidney Disease in People With Diabetes.

OBJECTIVE: To develop and validate a protein risk score for predicting chronic kidney disease (CKD) in patients with diabetes and compare its predictive performance with a validated clinical risk model (CKD Prediction Consortium [CKD-PC]) and CKD polygenic risk score. RESEARCH DESIGN AND METHODS: This cohort study included 2,094 patients with diabetes who had proteomics and genetic information and no history of CKD at baseline from the UK Biobank Pharma Proteomics Project. Based on nearly 3,000 plasma proteins, a CKD protein risk score including 11 proteins was constructed in the training set (including 1,047 participants; 117 CKD events). RESULTS: The median follow-up duration was 12.1 years. In the test set (including 1,047 participants; 112 CKD events), the CKD protein risk score was positively associated with incident CKD (per SD increment; hazard ratio 1.78; 95% CI 1.44, 2.20). Compared with the basic model (age + sex + race, C-index, 0.627; 95% CI 0.578, 0.675), the CKD protein risk score (C-index increase 0.122; 95% CI 0.071, 0.177), and the CKD-PC risk factors (C-index increase 0.175; 95% CI 0.126, 0.217) significantly improved the prediction performance of incident CKD, but the CKD polygenic risk score (C-index increase 0.007; 95% CI -0.016, 0.025) had no significant improvement. Adding the CKD protein risk score into the CKD-PC risk factors had the largest C-index of 0.825 (C-index from 0.802 to 0.825; difference 0.023; 95% CI 0.006, 0.044), and significantly improved the continuous 10-year net reclassification (0.199; 95% CI 0.059, 0.299) and 10-year integrated discrimination index (0.041; 95% CI 0.007, 0.083). CONCLUSIONS: Adding the CKD protein risk score to a validated clinical risk model significantly improved the discrimination and reclassification of CKD risk in patients with diabetes.

m6A RNA methylation drives kidney fibrosis by upregulating ß-catenin signaling.

N6-methyladenosine (m6A) methylation plays a crucial role in various biological processes and the pathogenesis of human diseases. However, its role and mechanism in kidney fibrosis remain elusive. In this study, we show that the overall level of m6A methylated RNA was upregulated and the m6A methyltransferase METTL3 was induced in kidney tubular epithelial cells in mouse models and human kidney biopsies of chronic kidney disease (CKD). Proximal tubule-specific knockout of METTL3 in mice protected kidneys against developing fibrotic lesions after injury. Conversely, overexpression of METTL3 aggravated kidney fibrosis in vivo. Through bioinformatics analysis and experimental validation, we identified ß-catenin mRNA as a major target of METTL3-mediated m6A modification, which could be recognized by a specific m6A reader, the insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3). METTL3 stabilized ß-catenin mRNA, increased ß-catenin protein and induced its downstream profibrotic genes, whereas either knockdown of IGF2BP3 or inhibiting ß-catenin signaling abolished its effects. Collectively, these results indicate that METTL3 promotes kidney fibrosis by stimulating the m6A modification of ß-catenin mRNA, leading to its stabilization and its downstream profibrotic genes expression. Our findings suggest that targeting METTL3/IGF2BP3/ß-catenin pathway may be a novel strategy for the treatment of fibrotic CKD.

Real-world effectiveness of early insulin therapy on the incidence of cardiovascular events in newly diagnosed type 2 diabetes.

Early insulin therapy is capable to achieve glycemic control and restore ß-cell function in newly diagnosed type 2 diabetes (T2D), but its effect on cardiovascular outcomes in these patients remains unclear. In this nationwide real-world study, we analyzed electronic health record data from 19 medical centers across China between 1 January 2000, and 26 May 2022. We included 5424 eligible patients (mean age 56 years, 2176 women/3248 men) who were diagnosed T2D within six months and did not have prior cardiovascular disease. Multivariable Cox regression models were used to estimate the associations of early insulin therapy (defined as the first-line therapy for at least two weeks in newly diagnosed T2D patients) with the incidence of major cardiovascular events including coronary heart disease (CHD), stroke, and hospitalization for heart failure (HF). During 17,158 persons years of observation, we documented 834 incident CHD cases, 719 stroke cases, and 230 hospitalized cases for HF. Newly diagnosed T2D patients who received early insulin therapy, compared with those who did not receive such treatment, had 31% lower risk of incident stroke, and 28% lower risk of hospitalization for HF. No significant difference in the risk of CHD was observed. We found similar results when repeating the aforesaid analysis in a propensity-score matched population of 4578 patients and with inverse probability of treatment weighting models. These findings suggest that early insulin therapy in newly diagnosed T2D may have cardiovascular benefits by reducing the risk of incident stroke and hospitalization for HF.

FAM3A plays a key role in protecting against tubular cell pyroptosis and acute kidney injury.

Acute kidney injury (AKI) is in high prevalence worldwide but with no therapeutic strategies. Programmed cell death in tubular epithelial cells has been reported to accelerate a variety of AKI, but the major pathways and underlying mechanisms are not defined. Herein, we identified that pyroptosis was responsible for AKI progression and related to ATP depletion in renal tubular cells. We found that FAM3A, a mitochondrial protein that assists ATP synthesis, was decreased and negatively correlated with tubular cell injury and pyroptosis in both mice and patients with AKI. Knockout of FAM3A worsened kidney function decline, increased macrophage and neutrophil cell infiltration, and facilitated tubular cell pyroptosis in ischemia/reperfusion injury model. Conversely, FAM3A overexpression alleviated tubular cell pyroptosis, and inhibited kidney injury in ischemic AKI. Mechanistically, FAM3A promoted PI3K/AKT/NRF2 signaling, thus blocking mitochondrial reactive oxygen species (mt-ROS) accumulation. NLRP3 inflammasome sensed the overload of mt-ROS and then activated Caspase-1, which cleaved GSDMD, pro-IL-1ß, and pro-IL-18 into their mature forms to mediate pyroptosis. Of interest, NRF2 activator alleviated the pro-pyroptotic effects of FAM3A depletion, whereas the deletion of NRF2 blocked the anti-pyroptotic function of FAM3A. Thus, our study provides new mechanisms for AKI progression and demonstrates that FAM3A is a potential therapeutic target for treating AKI.

Urinary cytokeratin 20 as a predictor for chronic kidney disease following acute kidney injury.

BACKGROUNDIdentifying patients with acute kidney injury (AKI) at high risk of chronic kidney disease (CKD) progression remains a challenge.METHODSKidney transcriptome sequencing was applied to identify the top upregulated genes in mice with AKI. The product of the top-ranking gene was identified in tubular cells and urine in mouse and human AKI. Two cohorts of patients with prehospitalization estimated glomerular filtration rate (eGFR) ≥ 45 mL/min/1.73 m2 who survived over 90 days after AKI were used to derive and validate the predictive models. AKI-CKD progression was defined as eGFR < 60 mL/min/1.73 m2 and with minimum 25% reduction from baseline 90 days after AKI in patients with prehospitalization eGFR ≥ 60 mL/min/1.73 m2. AKI-advanced CKD was defined as eGFR < 30 mL/min/1.73 m2 90 days after AKI in those with prehospitalization eGFR 45-59 mL/min/1.73 m2.RESULTSKidney cytokeratin 20 (CK20) was upregulated in injured proximal tubular cells and detectable in urine within 7 days after AKI. High concentrations of urinary CK20 (uCK20) were independently associated with the severity of histological AKI and the risk of AKI-CKD progression. In the Test set, the AUC of uCK20 for predicting AKI-CKD was 0.80, outperforming reported biomarkers for predicting AKI. Adding uCK20 to clinical variables improved the ability to predict AKI-CKD progression, with an AUC of 0.90, and improved the risk reclassification.CONCLUSIONThese findings highlight uCK20 as a useful predictor for AKI-CKD progression and may provide a tool to identify patients at high risk of CKD following AKI.FUNDINGNational Natural Science Foundation of China, National Key R&D Program of China, 111 Plan, Guangdong Key R&D Program.

Dipeptidyl peptidase 4 inhibitors vs. metformin for new-onset dementia: a propensity score-matched cohort study.

BACKGROUND: Hypoglycemic pharmacotherapy interventions for alleviating the risk of dementia remains controversial, particularly about dipeptidyl peptidase 4 (DPP4) inhibitors versus metformin. Our objective was to investigate whether the initiation of DPP4 inhibitors, as opposed to metformin, was linked to a reduced risk of dementia. METHODS: We included individuals with type 2 diabetes over 40 years old who were new users of DPP4 inhibitors or metformin in the Chinese Renal Disease Data System (CRDS) database between 2009 and 2020. The study employed Kaplan-Meier and Cox regression for survival analysis and the Fine and Gray model for the competing risk of death. RESULTS: Following a 1:1 propensity score matching, the analysis included 3626 DPP4 inhibitor new users and an equal number of metformin new users. After adjusting for potential confounders, the utilization of DPP4 inhibitors was associated with a decreased risk of all-cause dementia compared to metformin (hazard ratio (HR) 0.63, 95% confidence interval (CI) 0.45-0.89). Subgroup analysis revealed that the utilization of DPP4 inhibitors was associated with a reduced incidence of dementia in individuals who initiated drug therapy at the age of 60 years or older (HR 0.69, 95% CI 0.48-0.98), those without baseline macrovascular complications (HR 0.62, 95% CI 0.41-0.96), and those without baseline microvascular complications (HR 0.67, 95% CI 0.47-0.98). CONCLUSION: In this real-world study, we found that DPP4 inhibitors presented an association with a lower risk of dementia in individuals with type 2 diabetes than metformin, particularly in older people and those without diabetes-related comorbidities.

Association of accelerometer-measured physical activity and its change with progression to chronic kidney disease in adults with type 2 diabetes and overweight/obesity.

OBJECTIVE: To examine the long-term association of objectively measured moderate-to-vigorous physical activity (MVPA) and its longitudinal changes with progression to chronic kidney disease (CKD) in patients with type 2 diabetes (T2D) and overweight/obesity. METHODS: This study included 1746 participants in the Look AHEAD trial with baseline estimated glomerular filtration rate (eGFR)≥60 mL/min/1.73 m2. MVPA was measured at baseline, year 1, year 4 and year 8 using an RT3 accelerometer. The outcome was progression to CKD, defined as eGFR<60 mL/min per 1.73 m2 with a drop of ≥30% or end-stage kidney disease. Cox hazards models were fitted to examine the association between MVPA and outcomes. RESULTS: Over a median follow-up of 12.0 years, 567 participants experienced progression to CKD. Overall, there was a linear inverse association of cumulative average total MVPA (per 100 min/week higher amount, HR: 0.91; 95% CI: 0.86 to 0.96) and MVPA accumulated in bouts of ≥10 min (per 100 minutes/week higher amount, HR: 0.81; 95% CI: 0.72 to 0.91) with progression to CKD. Moreover, an increase in total MVPA from baseline to year 4 (the fourth quartile, ≥63.2 min/week) was associated with a 33% lower risk of progression to CKD compared with the largest MVPA reduction (the first quartile, <-198.3 min/week). A lower risk of progression to CKD was also observed for increases in MVPA accumulated in bouts of both <10 min and ≥10 min. CONCLUSIONS: Longer MVPA time and increases in MVPA was associated with a reduced risk of progression to CKD in adults with overweight/obesity and T2D.

MAGL protects against renal fibrosis through inhibiting tubular cell lipotoxicity.

Rationale: Renal fibrosis, with no therapeutic approaches, is a common pathological feature in various chronic kidney diseases (CKD). Tubular cell injury plays a pivotal role in renal fibrosis. Commonly, injured tubular cells exhibit significant lipid accumulation. However, the underlying mechanisms remain poorly understood. Methods: 2-arachidonoylglycerol (2-AG) levels in CKD patients and CKD model specimens were measured using mass spectrometry. 2-AG-loaded nanoparticles were infused into unilateral ureteral obstruction (UUO) mice. Lipid accumulation and renal fibrosis were tested. Furthermore, monoacylglycerol lipase (MAGL), the hydrolyzing enzyme of 2-AG, was assessed in CKD patients and models. Tubular cell-specific MAGL knock-in mice were generated. Moreover, MAGL recombination protein was also administered to unilateral ischemia reperfusion injury (UIRI) mice. Besides, a series of methods including RNA sequencing, metabolomics, primary cell culture, lipid staining, etc. were used. Results: 2-AG was increased in the serum or kidneys from CKD patients and models. Supplement of 2-AG further induced lipid accumulation and fibrogenesis through cannabinoid receptor type 2 (CB2)/ß-catenin signaling. ß-catenin knockout blocked 2-AG/CB2-induced fatty acid ß-oxidation (FAO) deficiency and lipid accumulation. Remarkably, MAGL significantly decreased in CKD, aligning with lipid accumulation and fibrosis. Specific transgene of MAGL in tubular cells significantly preserved FAO, inhibited lipid-mediated toxicity in tubular cells, and finally retarded fibrogenesis. Additionally, supplementation of MAGL in UIRI mice also preserved FAO function, inhibited lipid accumulation, and protected against renal fibrosis. Conclusion: MAGL is a potential diagnostic marker for kidney function decline, and also serves as a new therapeutic target for renal fibrosis through ameliorating lipotoxicity.

Relationship of dietary intake of food folate and synthetic folic acid intake from fortified foods with all-cause mortality in individuals with chronic kidney disease.

OBJECTIVE: To evaluate the association of the dietary intake of food folate (natural folate) and synthetic folic acid intake from fortified foods with the risk of all-cause mortality and end-stage kidney disease (ESKD) among the chronic kidney disease (CKD) population in regions with folic acid fortification. METHODS: 4028 individuals with established CKD in Chronic Renal Insufficiency Cohort (CRIC) were included. Diet was assessed using a validated diet history questionnaire at the baseline, year 2, and year 4, and nutrient intake, including food folate and folic acid from fortified foods, was estimated using the National Nutrient Database. The outcomes were all-cause mortality and ESKD. The results for all-cause mortality were further validated using the data from National Health and Nutrition Examination Surveys (NHANES). RESULTS: During a median follow-up of 11.1 years, 1155 deaths and 938 ESKD cases occurred. Compared with the first quartile of food folate intake, the third (HR: 0.74; 95% CI: 0.62, 0.90) and fourth (HR: 0.79; 95% CI: 0.63, 0.98) quartiles had a lower risk of all-cause mortality. Nevertheless, there was no significant association of synthetic folic acid intake from fortified foods with all-cause mortality. Similar results were observed for ESKD. Consistently, in NHANES, food folate intake and serum 5-methyltetrahydrofolate, but not folic acid intake, were inversely associated with all-cause mortality, while serum unmetabolized folic acid was positively associated with all-cause mortality in CKD participants. CONCLUSIONS: Higher intake of dietary natural folate, but not synthetic folic acid intake from fortified foods, was associated with lower risks of all-cause mortality and ESKD among CKD participants.

The influencing factors of the erythropoietin resistance index and its association with all-cause mortality in maintenance hemodialysis patients.

Anemia is a common complication of chronic kidney disease with major option treatment of erythropoiesis-stimulating agents (ESAs). This study aimed to investigate the influencing factors of erythropoietin resistance index (ERI) and its association with mortality in maintenance hemodialysis (MHD) patients. Patients enrolled from China Dialysis Outcomes and Practice Patterns Study (DOPPS) 5 were included. ERI was calculated as follows: ESA (IU/week)/weight (kg, post-dialysis)/hemoglobin level (g/dL). The Cox regression model was used to analyze the influencing factors on survival outcomes. Stepwise multivariate logistic regression was used to identify the related risk factors, and subgroup analyses were performed. A total of 1270 MHD subjects (687 males and 583 females) were included, with an average age of 60 (49.0, 71.0) years. All subjects were divided into two groups by the median ERI of 14.03. Multivariate logistic regression showed that dialysis vintage (OR 0.957, 95% CI: 0.929-0.986), white blood cells (OR 0.900, 95% CI: 0.844-0.960), high flux dialyzer use (OR 0.866, 95% CI: 0.755-0.993), body mass index (OR 0.860, 95% CI: 0.828-0.892), males (OR 0.708, 95% CI: 0.625-0.801), and albumin (OR 0.512, 95% CI: 0.389-0.673) had a negative association with high ERI baseline (all p < 0.05). There were 176 (13.9%) deaths in total including 89 cardiac/vascular deaths during follow-up. Cox regression analysis showed that ERI was positively associated with all-cause mortality, especially in some subgroups. ERI was associated with increased all-cause mortality in MHD patients, indicating the possibility of death prediction by ERI. Patients with high ERI warrant more attention.

Klotho-derived peptide 1 inhibits cellular senescence in the fibrotic kidney by restoring Klotho expression via posttranscriptional regulation.

Background: Klotho deficiency is a common feature of premature aging and chronic kidney disease (CKD). As such, restoring Klotho expression could be a logic strategy for protecting against various nephropathies. In this study, we demonstrate that KP1, a Klotho-derived peptide, inhibits cellular senescence by restoring endogenous Klotho expression. Methods: The effects of KP1 on cellular senescence and Klotho expression were assessed in mouse models of CKD. RNA-sequencing was employed to identify the microRNA involved in regulating Klotho by KP1. Gain- or loss-of-function approaches were used to assess the role of miR-223-3p and IncRNA-TUG1 in regulating Klotho and cellular senescence. Results: KP1 inhibited senescence markers p21, p16 and γ-H2AX in tubular epithelial cells of diseased kidneys, which was associated with its restoration of Klotho expression at the posttranscriptional level. Profiling of kidney microRNAs by RNA sequencing identified miR-223-3p that bound to Klotho mRNA and inhibited its protein expression. Overexpression of miR-223-3p inhibited Klotho and induced p21, p16 and γ-H2AX, which were negated by KP1. Conversely, inhibition of miR-223-3p restored Klotho expression, inhibited cellular senescence. Furthermore, miR-223-3p interacted with lncRNA-TUG1 and inhibited its expression. Knockdown of lncRNA-TUG1 increased miR-223-3p, aggravated Klotho loss and worsened cellular senescence, whereas KP1 mitigated all these changes. Conclusion: These studies demonstrate that KP1 inhibits cellular senescence and induces Klotho expression via posttranscriptional regulation mediated by miR-223-3p and lncRNA-TUG1. By restoring endogenous Klotho, KP1 elicits a broad spectrum of protective actions and could serve as a promising therapeutic agent for fibrotic kidney disorders.