Kidney Function Measures and Mortality: A Mendelian Randomization Study.

RATIONALE & OBJECTIVE: Individuals with a low estimated glomerular filtration rate (eGFR) are at a high risk of death. However, the causes underpinning this association are largely uncertain. This study aimed to assess the causal relationship of low eGFR with all-cause and cause-specific mortality. STUDY DESIGN: Retrospective cohort study incorporating Mendelian randomization (MR). SETTING & PARTICIPANTS: Individual-level data from 436,214 White participants (54.3% female; aged 56.8±8.0 years) included in the UK Biobank. EXPOSURES: eGFR estimated using cystatin C (eGFRcyst). OUTCOMES: The outcomes of interest included all-cause mortality, cardiovascular mortality, cancer mortality, infection mortality, and other-cause mortality. ANALYTICAL APPROACH: Cox proportional hazards analysis for the conventional observational analyses; linear and nonlinear MR analyses implemented using genetic allele scores as instrumental variables representing kidney function to estimate the effect of kidney function on the survival outcomes. RESULTS: During a median follow-up of 12.1 years, there were 30,489 deaths, 6,098 of which were attributed to cardiovascular events, 15,538 to cancer, 1,516 to infection, and 7,227 to other events. In the conventional observational analysis, eGFRcyst exhibited a nonlinear association with all the outcomes. MR analysis suggested that a genetically predicted lower eGFRcyst was linearly associated with a higher rate of cardiovascular mortality (HR, 1.43; 95% CI, 1.18-1.75) across the entire measurement range (every 10-mL/min/1.73m2 decrement). Nonetheless, no causal associations between eGFRcyst and all-cause mortality (HR, 1.07; 95% CI, 0.98-1.17) or any types of noncardiovascular mortality were detected. LIMITATIONS: Potential misclassification of the actual cause of death, a nonrepresentative sample, and potential error in the interpretation of the magnitude of associations generated in MR analyses. CONCLUSIONS: These findings suggest a potential causal association between low eGFR and cardiovascular mortality in the general population, but no causal relationship with all-cause mortality or noncardiovascular mortality was observed. Further studies in other populations are warranted to confirm these findings. PLAIN-LANGUAGE SUMMARY: This study investigated the existence of a causal relationship between lower kidney function and death of different causes. Using data from 436,214 people in the United Kingdom, we applied conventional statistical analyses and those incorporating genetic data to implement Mendelian randomization, an approach that estimates causal associations. The observational analysis showed a nonlinear association between kidney function and various types of mortality outcomes. However, Mendelian randomization analysis suggested a linear increase in the risk of cardiovascular mortality with lower kidney function, but no causal link between the level of kidney function and all-cause or noncardiovascular mortality was identified. Managing kidney health may help reduce cardiovascular mortality, but caution is needed in interpreting the magnitudes of these results. Further validation in other populations and in those with advanced kidney failure is needed.

COVID-19 increases extracorporeal coagulation during hemodialysis associated with upregulation of vWF/FBLN5 signaling in patients with severe/critical symptoms.

BACKGROUND: COVID-19 has been shown to increase the risk of extracorporeal coagulation during hemodialysis in patients, but the underlying mechanism remains unclear. This study aimed to investigate the effect and mechanism of COVID-19 on the risk of extracorporeal coagulation in patients with chronic kidney disease undergoing hemodialysis. METHODS: A retrospective analysis of the extracorporeal coagulation status of 339 hemodialysis patients at our center before and after COVID-19 infection was performed, including subgroup analyses. Post-infection blood composition was analyzed by protein spectrometry and ELISA. RESULTS: Compared to the pre-COVID-19 infection period, COVID-19-induced extracorporeal coagulation predominantly occurred in patients with severe/critical symptoms. Further proteomic analysis demonstrated that in patients with severe/critical symptoms, the coagulation cascade reaction, platelet activation, inflammation, and oxidative stress-related pathways were significantly amplified compared to those in patients with no/mild symptoms. Notably, the vWF/FBLN5 pathway, which is associated with inflammation, vascular injury, and coagulation, was significantly upregulated. CONCLUSIONS: Patients with severe/critical COVID-19 symptoms are at a higher risk of extracorporeal coagulation during hemodialysis, which is associated with the upregulation of the vWF/FBLN5 signaling pathway. These findings highlight the importance of early anticoagulant therapy initiation in COVID-19 patients with severe/critical symptoms, particularly those undergoing hemodialysis. Additionally, vWF/FBLN5 upregulation may be a novel mechanism for virus-associated thrombosis/coagulation.

Risk factors and prognosis for latent tuberculosis infection in dialysis patients: A retrospective cohort study at a single tertiary care center.

INTRODUCTION: Recent studies report that latent tuberculosis infection (LTBI) may lead to an increased risk of cardiovascular disease (CVD) that led us to hypothesize that LTBI may play an important role in major adverse cardiovascular events (MACE) in dialysis patients. METHODS: A single-center retrospective cohort study was conducted. A total of 270 patients undergoing hemodialysis or peritoneal dialysis more than 3 months were included. The interferon enzyme-linked immunospot (IFN-γ ELISPOT) assay was used for the diagnosis of LTBI. Primary endpoints were MACE, including all-cause death and acute coronary syndrome (ACS). The association between LTBI and MACE was examined using multivariate Cox proportional hazards regression after adjusting for covariates and Kaplan-Meier survival analysis. RESULTS: In our study, the patients were classified into LTBI (n = 47) or non-LTBI (n = 223) groups. Independent risk factors for LTBI in dialysis population were prior tuberculosis (TB) history (odds ratio [OR] 4.817 [1.064-22.306]), tobacco use (OR 2.903 [1.155-7.299]), and older age (OR 1.027 [1.002-1.053]). After a median follow-up of 39 months, the incidence of active TB was 6.4% versus 0% in dialysis patients with and without LTBI, respectively (p = 0.005). Multivariate Cox analysis showed that LTBI was significantly associated with MACE (hazard ratio [HR] 2.540 [1.490-4.350]) after adjustment for potential confounders. CONCLUSIONS: Prior TB history, tobacco use, and the elderly can be used to select cost-effective LTBI screening target groups in dialysis patients. LTBI is not only closely related to active TB but also an independent risk factor for higher incidence of MACE in dialysis population.

A modified renal risk score for Chinese patients with antineutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND: The renal risk score (RRS) is a useful tool to predict end-stage renal disease (ESRD) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The current study aimed to validate the predictive performance of RRS and to further modify this model in Chinese AAV patients. METHODS: Two hundred and seventy-two patients diagnosed with AAV confirmed by renal biopsies were retrospectively enrolled from a single center. The RRS was calculated based on 3 categorical variables, i.e., the proportion of normal glomeruli, the proportion of interstitial fibrosis and tubular atrophy (IF/TA), and eGFR at biopsy, classifying these patients into low-, medium-, and high-risk groups. In addition, a modified model was developed based on the RRS and was further validated in another independent cohort of 117 AAV patients. The predictive performance of each model was evaluated according to discrimination and calibration. RESULTS: Patients were classified by the RRS into low- (26.5%), medium- (46.7%), and high-risk (26.8%) groups, with 120-month renal survival rates of 93.3%, 57.2%, and 18.4%, respectively (P < 0.001). The RRS showed good discrimination but less satisfactory calibration. Therefore, a modified model with improved discrimination and calibration was developed in Chinese AAV patients, with eGFR, proportion of normal glomeruli (both as continuous variables), and IF/TA (< 25%, 25-50%, > 50%) included. Internal and external validation of the modified model were performed. Finally, an online risk prediction tool was developed based on the modified model. CONCLUSIONS: The RRS was an independent predictor of ESRD of AAV patients. The modified model could predict the probability of ESRD for AAV patients with improved performance in Chinese AAV patients.

Spatial proteomics landscape and immune signature analysis of renal sample of lupus nephritis based on laser-captured microsection.

OBJECTIVE: We aimed to reveal a spatial proteomic and immune signature of kidney function regions in lupus nephritis (LN). MATERIAL AND METHODS: The laser capture microdissection (LCM) was used to isolate the glomerulus, tubules, and interstitial of the kidney from paraffin samples. The data-independent acquisition (DIA) method was used to collect proteomics data. The bioinformatic analysis was performed. RESULTS: A total of 49,658 peptides and 4056 proteins were quantitated. Our results first showed that a high proportion of activated NK cells, naive B cells, and neutrophils in the glomerulus, activated NK cells in interstitial, and resting NK cells were accumulated in tubules in LN. The immune-related function analysis of differential expression proteins in different regions indicated that the glomerulus and interstitial were major sites of immune disturbance and regulation connected with immune response activation. Furthermore, we identified 7, 8, and 9 hub genes in LN's glomerulus, renal interstitial, and tubules. These hub genes were significantly correlated with the infiltration of immune cell subsets. We screened out ALB, CTSB, LCN2, A2M, CDC42, VIM, LTF, and CD14, which show higher performance as candidate biomarkers after correlation analysis with clinical indexes. The function within three regions of the kidney was analyzed. The differential expression proteins (DEGs) between interstitial and glomerulus were significantly enriched in the immune-related biological processes, and myeloid leukocyte-mediated immunity and cellular response to hormone stimulus. The DEGs between tubules and glomerulus were significantly enriched in cell activation and leukocyte-mediated immunity. While the DEGs between tubules and interstitial were enriched in response to lipid, antigen processing, and presentation of peptide antigen response to oxygen-containing compound, the results indicated a different function within kidney regions. CONCLUSIONS: Collectively, we revealed spatial proteomics and immune signature of LN kidney regions by combined using LCM and DIA.

Retinopathy is associated with impaired cognition in patients undergoing peritoneal dialysis.

Objective: Previous studies have shown a relationship between retinopathy and cognition including population with and without chronic kidney disease (CKD) but data regarding peritoneal dialysis (PD) are limited. This study aims to investigate the relationship between retinopathy and cognitive impairment in patients undergoing peritoneal dialysis (PD). Methods: In this observational study, we recruited a total of 107 participants undergoing PD, consisting of 48 men and 59 women, ages ranging from 21 to 78 years. The study followed a cross-sectional design. Retinal microvascular characteristics, such as geometric changes in retinal vascular including tortuosity, fractal dimension (FD), and calibers, were assessed. Retinopathy (such as retinal hemorrhage or microaneurysms) was evaluated using digitized photographs. The Modified Mini-Mental State Examination (3MS) was performed to assess global cognitive function. Results: The prevalence rates of retinal hemorrhage, microaneurysms, and retinopathy were 25%, 30%, and 43%, respectively. The mean arteriolar and venular calibers were 63.2 and 78.5 µm, respectively, and the corresponding mean tortuosity was 37.7 ± 3.6 and 37.2 ± 3.0 mm-1. The mean FD was 1.49. After adjusting for age, sex, education, mean arterial pressure, and Charlson index, a negative association was revealed between retinopathy and 3MS scores (regression coefficient: -3.71, 95% confidence interval: -7.09 to -0.33, p = 0.03). Conclusions: Retinopathy, a condition common in patients undergoing PD, was associated with global cognitive impairment. These findings highlight retinopathy, can serve as a valuable primary screening tool for assessing the risk of cognitive decline.

Association between diabetes mellitus and health-related quality of life among patients with chronic kidney disease: results from the Chinese Cohort Study of Chronic Kidney Disease (C-STRIDE).

BACKGROUND: The prevalence of diabetes mellitus (DM) among patients with chronic kidney disease (CKD) has been increasing in recent years in China. This study aimed to evaluate the association between DM and health-related quality of life (HRQOL) in patients with CKD. METHODS: In our study, participants with CKD stage 1 to 4 from 39 centers in China were screened and enrolled. The Kidney Disease Quality of Life (KDQOL™-36) questionnaire was used to assess HRQOL. Participants were divided into a diabetic group and a non-diabetic group. Demographic data, clinical data, and HRQOL scores were compared between the two groups. Multivariable robust regression was used to analyze the factors related to HRQOL in CKD patients. RESULTS: A population of 2742 CKD patients was included in this study. CKD patients with DM were older and had lower education level, longer treatment periods and a higher prevalence of cardiovascular disease than CKD patients without DM (P < 0.05). HRQOL scores in the "symptoms and problems", "effects of kidney disease", and "SF-12 physical function" dimensions were significantly lower in the diabetic group than the non-diabetic group (86.88 ± 13.76 vs. 90.59 ± 10.75, 84.78 ± 14.86 vs. 87.28 ± 12.45, and 41.40 ± 9.77 vs. 45.40 ± 8.82, respectively, all P < 0.05). DM was negatively correlated with the symptoms and problems (regression coefficient for log transformed [175-score] = 0.010) and the SF-12 physical function dimension (regression coefficient = - 2.18) (all P < 0.05). CONCLUSION: HRQOL of diabetic patients with CKD was worse than that of non-diabetic patients with CKD. DM was an independent and negative factor affecting HRQOL in patients with CKD.

Histone demethylase KDM6B regulates human podocyte differentiation in vitro.

Podocytes are terminally differentiated and highly specialized glomerular cells, which have an essential role as a filtration barrier against proteinuria. Histone methylation has been shown to influence cell development, but its role in podocyte differentiation is less understood. In this study, we first examined the expression pattern of histone demethylase KDM6B at different times of cultured human podocytes in vitro We found that the expression of KDM6B and podocyte differentiation markers WT1 and Nephrin are increased in the podocyte differentiation process. In cultured podocytes, KDM6B knockdown with siRNA impaired podocyte differentiation and led to expression down-regulation of WT1 and Nephrin. The treatment of podocytes with GSK-J4, a specific KDM6B inhibitor, can also obtain similar results. Overexpression of WT1 can rescue differentiated phenotype impaired by disruption of KDM6B ChIP (chromatin immunoprecipitation) assay further indicated that KDM6B can bind the promoter region of WT1 and reduce the histone H3K27 methylation. Podocytes in glomeruli from nephrotic patients exhibited increased KDM6B contents and reduced H3K27me3 levels. These data suggest a role for KDM6B as a regulator of podocyte differentiation, which is important for the understanding of podocyte function in kidney development and related diseases.

Down-regulation of serum miR-151a-3p is associated with renal tissue activity in class IV lupus nephritis.

OBJECTIVES: The aim of this study was to explore the value of serum miRNA for evaluating renal tissue activity in patients with class IV lupus nephritis (LN). METHODS: First, we used a microRNA array to identify miRNAs differentially expressed between class IV LN patients and healthy volunteers (n=4/group). Then, we analysed the association between these identified miRNAs and renal tissue activity in class IV LN patients. Finally, to validate the results, 20 class IV LN patients (confirmed by renal biopsy) and 20 healthy control volunteers were further studied. RESULTS: We found 23 miRNAs to be significantly differentially expressed between the 2 groups. We selected 5 of these miRNAs (miR-3165, miR-4762-5p, miR-146a-5p, miR-151a-3p, and miR-21-5p) for further experiments. In validation experiments, expression of miRNA-151a-3p was significantly down-regulated in the class IV LN group compared to that in the control group (p<0.01) and was negatively correlated with the activity index (AI) in the class IV LN group(r=-0.526, p=0.017); the internal correlation was described with a linear fitting equation (p<0.01). CONCLUSIONS: Serum miR-151a-3p expression was decreased in class IV LN patients compared with healthy control volunteers and was negatively correlated with renal tissue activity. Thus, miR-151a-3p may play a employed for diagnosing class IV LN and evaluating renal tissue activity.

Sleep Disorders and Cognitive Impairment in Peritoneal Dialysis: A Multicenter Prospective Cohort Study.

BACKGROUND: Patients with chronic kidney disease experience a high burden of sleep disorders, and there are associations between sleep disorders and cognitive impairment. OBJECTIVES: Based on our previous cross-sectional survey on cognitive impairment in peritoneal dialysis, we further explored the relationship between sleep disorders and cognitive impairment, and predictors for declining cognitive function. METHOD: We conducted a multicenter prospective cohort study enrolling 458 clinically stable patients on peritoneal dialysis who were then followed up for 2 years.Demographic data, comorbidities, depression, and biochemistry data were collected at baseline. Sleep disorders including insomnia, restless legs syndrome, sleep apnea syndrome, excessive daytime sleepiness, possible narcolepsy, sleep walking and nightmares, and possible rapid eye movement behavior disorders were assessed using a panel of specific sleep questionnaires at baseline and in a second survey. Global cognitive function was measured at baseline and in a second survey, using the Modified Mini-Mental State Examination. Specific cognitive domains were evaluated using Trail-Making Test Forms A and B for executive function, and subtests of the Battery for the Assessment of Neuropsychological Status were used to asses immediate and delayed memory, visuospatial skills, and language ability. RESULTS: Sleep disorders were common among peritoneal dialysis patients. The prevalence of cognitive impairment evaluated by the Modified Mini-Mental State Examination (3MS) increased from 19.8 to 23.9%. Possible narcolepsy was associated with decreased Modified Mini-Mental State Examination scores at baseline. During follow-up, sleepwalking and nightmares were associated with higher risks of declined delayed memory in the longitudinal study. CONCLUSIONS: Possible narcolepsy was associated with general cognitive dysfunction, and sleep walking and nightmares were risk factors for impaired delayed memory.