Metabolomic profiling of overnight peritoneal dialysis effluents predicts the peritoneal equilibration test type

This study primarily aimed to evaluate whether peritoneal equilibration test (PET) results can be predicted through the metabolomic analysis of overnight peritoneal dialysis (PD) effluents. From a total of 125 patients, overnight PD effluents on the day of the first PET after PD initiation were analyzed. A modified 4.25% dextrose PET was performed, and the PET type was categorized according to the dialysate-to-plasma creatinine ratio at the 4-h dwell time during the PET as follows: high, high average, low average, or low transporter. Nuclear magnetic resonance (NMR)-based metabolomics was used to analyze the effluents and identify the metabolites. The predictive performances derived from the orthogonal projection to latent structure discriminant analysis (OPLS-DA) modeling of the NMR spectrum were estimated by calculating the area under the curve (AUC) using receiver operating characteristic curve analysis. The OPLS-DA score plot indicated significant metabolite differences between high and low PET types. The relative concentrations of alanine and creatinine were greater in the high transporter type than in the low transporter type. The relative concentrations of glucose and lactate were greater in the low transporter type than in the high transporter type. The AUC of a composite of four metabolites was 0.975 in distinguish between high and low PET types. Measured PET results correlated well with the total NMR metabolic profile of overnight PD effluents.Peer reviewe

Association of Chronic Kidney Disease With Atrial Fibrillation in the General Adult Population: A Nationwide Population‐Based Study

Background The incidences of atrial fibrillation (AF) and chronic kidney disease (CKD) are increasing, and AF is prevalent in patients with CKD. However, few studies have investigated the incidence or association of AF in a large CKD population from a longitudinal study. Methods and Results From a nationwide cohort, a total of 4 827 987 Korean individuals without prior AF, who received biennial health checkups provided by the National Health Insurance Service between 2009 and 2012 in Korea, were analyzed. Incidence of AF was ascertained through the end of 2018. During a median follow‐up of 8.1 years, the annual incidence rate of AF was 1.17 per 1000 person‐years among subjects without CKD, 1.55 for stage 1 CKD, 1.86 for stage 2 CKD, 2.1 for stage 3 CKD, and 4.33 for stage 4 CKD. In Fine‐Gray regression models, CKD was associated with an increased risk of AF; the adjusted hazard ratios and 95% CIs of AF occurrence were 1.77 (1.69–1.85), 1.85 (1.80–1.91), 1.99 (1.95–2.04), and 4.04 (3.07–5.33) in individuals with CKD stages 1, 2, 3, and 4, respectively, compared with non‐CKD. The association between CKD and incident AF remained statistically significant after adjustment for multiple confounding factors and was consistent across subgroups stratified by sex and age. Conclusions CKD is associated with an increased incidence of AF. Even mild CKD is associated with incident AF, and there was a stepwise increase in the risk of incident AF with a decrease in renal function

Low Klotho/Fibroblast Growth Factor 23 Ratio Is an Independent Risk Factor for Renal Progression in Chronic Kidney Disease: Finding From KNOW-CKD

BackgroundWe aimed to evaluate soluble Klotho and circulating fibroblast growth factor 23 (FGF23) ratio as a risk factor for renal progression, cardiovascular (CV) events, and mortality in chronic kidney disease (CKD). MethodsWe analyzed 2,099 subjects from a CKD cohort whose soluble Klotho and C-terminal FGF23 levels were measured at enrollment. The Klotho to FGF23 ratio was calculated as Klotho values divided by FGF23 values + 1 (hereinafter called the Klotho/FGF23 ratio). Participants were categorized into quartiles according to Klotho/FGF23 ratio. The primary outcome was renal events, defined as the doubling of serum creatinine, 50% reduction of estimated glomerular filtration rate from the baseline values, or development of end-stage kidney disease. The secondary outcomes consisted of CV events and death. Changes in CV parameters at the time of enrollment and during follow-up according to the Klotho/FGF23 ratio were also examined. ResultsDuring the follow-up period of 64.0 +/- 28.2 months, 735 (35.1%) and 273 (13.0%) subjects developed renal events and composite outcomes of CV events and death, respectively. After adjustment, the first (HR: 1.36; 95% CI: 1.08-1.72, P = 0.010) and second (HR: 1.45; 95% CI: 1.15-1.83, P = 0.002) quartiles with regard to the Klotho/FGF23 ratio showed elevated risk of renal events as compared to the fourth quartile group. There was no significant association between Klotho/FGF23 ratio and the composite outcome of CV events and death. The prevalence of left ventricular hypertrophy and vascular calcification was higher in the low Klotho/FGF23 ratio quartiles at baseline and at the fourth-year follow-up. ConclusionsLow Klotho/FGF23 ratio was significantly associated with increased renal events in the cohort of Korean predialysis CKD patients.N

Hexokinase 2 is a molecular bridge linking telomerase and autophagy

<div><p>Autophagy is systematically regulated by upstream factors and nutrients. Recent studies reported that telomerase and hexokinase 2 [HK2) regulate autophagy through mTOR and that telomerase has the capacity to bind to the HK2 promoter. However, the molecular linkage among telomerase, HK2, and autophagy is not fully understood. Here, we show that HK2 connects telomerase to autophagy. HK2 inhibition in HepG2 cells suppressed TERT-induced autophagy activation and further enhancement by glucose deprivation. The HK2 downstream factor mTOR was responsible for the TERT-induced autophagy activation under glucose deprivation, implying that TERT promotes autophagy through an HK2-mTOR pathway. TERC played a role similar to that of TERT, and simultaneous expression of TERT and TERC synergistically enhanced HK2 expression and autophagy. At the gene level, TERT bound to the HK2 promoter at a specific region harboring the telomerase-responsive sequence ‘TTGGG.’ Mutagenesis of TERC and the TERT-responsive element in the HK2 promoter revealed that TERC is required for the binding of TERT to the HK2 promoter. We demonstrate the existence of a telomerase-HK2-mTOR-autophagy axis and suggest that inhibition of the interaction between telomerase and the HK2 promoter diminishes glucose starvation-induced autophagy.</p></div

Changes in the glymphatic system before and after dialysis initiation in patients with end-stage kidney disease

AbstractIntroduction The aims of this study were to evaluate 1) glymphatic system function in patients with end-stage kidney disease (ESKD) before initiating dialysis compared to healthy controls, and 2) changes in the glymphatic system function after kidney replacement therapy including dialysis in patients with ESKD using the diffusion tensor image analysis along the perivascular space (DTI-ALPS) method.Materials and methods This study was prospectively conducted at a single hospital. We enrolled 14 neurologically asymptomatic patients who first initiated hemodialysis or peritoneal dialysis for ESKD and 17 healthy controls. Patients had magnetic resonance imaging scans before initiating dialysis and again 3 months after initiating dialysis and the DTI-ALPS index was calculated. We compared the DTI-ALPS index before and after the initiation of dialysis and compared the DTI-ALPS index between the patients with ESKD and healthy control.Results There were differences in the DTI-ALPS index between ESKD patients before initiating dialysis and healthy controls (1.342 vs. 1.633, p = 0.003). DTI-ALPS index between ESKD patients before initiating dialysis and those after dialysis were not different (1.342 vs. 1.262, p = 0.386). There was a positive correlation between DTI-ALPS index and phosphate (r = 0.610, p = 0.020) in patients with ESKD.Conclusion We confirmed the presence of glymphatic dysfunction in patients with ESKD. However, there was no difference in the glymphatic system before and after dialysis initiation. This finding may be related to uremic toxins that are not removed by dialysis in patients with ESKD. This study can be used for the development of pathophysiology of patients with ESKD

TERT activates autophagy under normal and glucose-starvation conditions.

<p>(<b>A</b>) Relative <i>TERT</i> mRNA levels in control (shCTL) and TERT knockdown (KD) HepG2 cells (shT#1 and shT#3; triplicate). (<b>B–G</b>) Quantification and Western blot analysis of the LC3 maturation rate in control and TERT KD HepG2 cells under normal and glucose deprivation conditions. ACTIN was used as a loading control in the Western blots. Cells were starved of glucose and treated simultaneously with bafilomycin A1 (BafA1, 10 μM) or vehicle (NT). (<b>B</b> and <b>C</b>) The LC3 maturation rate in control and stable TERT KD HepG2 cells under glucose deprivation. (<b>D</b> and <b>E</b>) The LC3 maturation rate in control and siRNA-mediated transient TERT KD (siTERT) HepG2 cells under glucose deprivation. (<b>F</b> and <b>G</b>) The LC3 maturation rate in empty vector control (EV) and TERT-overexpressing (TERT) HepG2 cells under glucose deprivation. (<b>H</b>) Representative images of immunocytochemistry analysis of LC3 puncta in control and TERT KD (shTERT) HepG2 cells transfected with RFP-GFP-LC3 (left panel). Scale bar: 10 μm. The percentage of GFP(-)RFP(+) LC3 puncta were measured and normalized with the number of GFP(+)RFP(+) LC3 puncta under normal and 24 h glucose-starvation conditions (right panel). The graph represents the normalized GFP(-)RFP(+) puncta per cell. (<b>B-G</b>) Bafilomycin A1 was treated to promote accumulation of LC3-II by blocking its degradation. Error bars indicate standard deviation. *<i>p</i> < 0.05.</p

TERT binds to a TTGGG sequence on the HK2 promoter.

<p>(<b>A</b>) Relative <i>TERT</i> mRNA levels 48 h after transfection (n = 3) in HepG2 cells. (<b>B</b>) Schematic views of luciferase constructs harboring HK2 promoter with indicated length. Red spots indicate the sites of the ‘TTGGG’ sequences in the HK2 promoter. Brown spots indicate the sites of ‘TGGG’ sequences in the HK2 promoter. (<b>C</b>) Relative luciferase activity of 2, 1.7, and 0.8 kb-length HK2 promoters 24 h after ectopic overexpression of control vector (MOCK), wild-type (WT-TERT), and DN-TERT (triplicate) in HepG2 cells. HK2-luciferase activity was normalized based on pRL-tk-Luc. (<b>D</b> and <b>E</b>) RT-qPCR in triplicate (<b>D</b>) and Western blot (<b>E</b>) analyses for HK2 and ACTIN 48 h after transfection in HepG2 cells. (<b>F</b> and <b>G</b>) Western blot analysis for TERT and ACTIN (<b>F</b>, upper panel), and ChIP analyses of TERT-expressing cells with the indicated antibodies against the HK2 promoter (<b>F</b>, lower panel; <b>G</b>) 48 h after transfection in HepG2 cells. Error bars indicate standard deviation. **<i>p</i> < 0.01; ***<i>p</i> < 0.001.</p

HK2 and mTOR are required for TERT-induced autophagy activation.

<p>(<b>A</b>) Western blot analyses for FLAG, HK2, LC3, and ACTIN 72 h after siRNA transfection. The times 0 h and 8 h indicate how long the cells were deprived of glucose and simultaneously treated with bafilomycin A1 (10 μM). (<b>B</b>) Western blot analyses for GFP, LC3, and ACTIN 72 h after siRNA transfection. (<b>C</b>) Western blot analyses for phospho-S6K (pS6K) and S6K72 h after siRNA transfection (<b>C</b>, upper panel) and knockdown efficiency of TERT (<b>C</b>, lower panel) in control (siCTL) and TERT KD (siTERT) cells after 0 h or 12 h of glucose starvation. (<b>D</b>) Western blot analyses for phospho-S6K (pS6K), S6K, and GAPDH in control and stable TERT KD HepG2 cell lines after 0 h or 12 h of glucose starvation. (<b>E</b>) Western blot analyses of pS6K, S6K, FLAG, HK2, LC3, and ACTIN 48 h after transfection in cells treated with either rapamycin (25 nM) or DMSO for 3 hours.</p