Association between Monocyte Count and Risk of Incident CKD and Progression to ESRD

Comprehensive proteomics of monocytes indicates oxidative imbalance functionally related to inflammatory response in chronic kidney disease-related atherosclerosis

Atherosclerosis-induced cardiovascular events are the leading cause of mortality in chronic kidney disease (CKD) patients. Monocytes are involved in the formation of atherosclerotic plaques and mediate in the overproduction of ROS, promoting inflammation and oxidative stress. However, the relationship between monocytes, inflammation, and oxidative status in CKD-associated atherosclerosis has not been thoroughly investigated. Monocytes and plasma derived from two groups of CKD patients with varying degrees of atherosclerosis and two groups of patients with cardiovascular disease (CVD) and non-CKD atherosclerosis were analyzed. This study was designed to perform a comprehensive proteomic analysis of monocytes in combination with functional bioinformatics. In addition, a targeted investigation of oxidative stress- and inflammatory-related factors to explore CKD-associated atherosclerosis was applied. Dysregulation of proteins involved in lipid oxidation, cell survival, ROS synthesis and metabolism, and inflammatory responses has been revealed. The characteristic disturbances in the monocyte proteome changed with the progression of CKD. A closer examination of oxidative stress's triggers, mediators, and effects on protein and lipid levels showed alterations in the oxidative imbalance between CKD and CVD. CKD monocytes demonstrated a significant increase of oxidized glutathione without changing the level of its reduced form. Evaluation of enzymatic antioxidants, sources of ROS, and modifications caused by ROS also revealed significant alterations between the study groups. In CKD, inflammation and oxidative imbalance correlated and drove each other. However, in CVD, oxidative stress-related factors were associated with each other but not to inflammatory proteins. Moreover, lipid abnormalities were more specific to classical CVD and unrelated to CKD. Such a comprehensive characterization of monocytes and oxidative stress in CKD and CVD patients has never been presented so far. Obtained results support the involvement of distinct mechanisms underlying the acceleration of atherosclerotic and non-atherosclerotic CKD.

Gut-immune axis and cardiovascular risk in chronic kidney disease

Patients with chronic kidney disease (CKD) suffer from marked cardiovascular morbidity and mortality, so lowering the cardiovascular risk is paramount to improve quality of life and survival in CKD. Manifold mechanisms are hold accountable for the development of cardiovascular disease (CVD), and recently inflammation arose as novel risk factor significantly contributing to progression of CVD. While the gut microbiome was identified as key regulator of immunity and inflammation in several disease, CKD-related microbiome-immune interaction gains increasing importance. Here, we summarize the latest knowledge on microbiome dysbiosis in CKD, subsequent changes in bacterial and host metabolism and how this drives inflammation and CVD in CKD. Moreover, we outline potential therapeutic targets along the gut-immune-cardiovascular axis that could aid the combat of CVD development and high mortality in CKD.

The Impact of Hematological Indices on the Occurrence of Delayed Graft Function (DGF) of Transplanted Kidney

BACKGROUND

to analyse the effect of haematological indices on the occurrence of Delayed Graft Function (DGF) in patients undergoing kidney transplantation and on the function of the transplanted kidney on the 7th postoperative day.

METHODS

365 recipients who underwent kidney transplantation from a donor with known brain death between 2010 and 2017 were included in this retrospective study. Information from patient medical records, donor medical records, and donation and transplantation protocols was used for analysis. Statistica 13 was used for statistical analysis.

RESULTS

In the study group, DGF occurred in 144 recipients (39.45%), and Non-Graft Function (NGF) occurred in 12 recipients (3.29%). Recipients who developed DGF had a significantly higher Neutrophil/Monocyte Ratio (NMR) before renal transplantation (p = 0.048), a lower NMR value on postoperative day 1 (p < 0.001), and a difference between the values on day 1 and before surgery (p < 0.001). In addition, they had a significantly lower Lymphocyte/Monocyte Ratio (LMR) on postoperative day 1 LMR 1 (p < 0.001). It was shown that the value of the indices based on the ROC curve-NMR1 > 29.29, NMR1-0 > 22.71, and LMR1 > 1.74 (respectively: AUC = 0.624; 95% CI 0.566-0.682; and p < 0.001/AUC = 0.622; 95% CI 0.563-0.680; and p < 0.001/AUC = 0.610; 95% CI 0.550-0.670; and p < 0.001)-can be used to identify recipients with a significant probability of DGF.

CONCLUSIONS

the NMR and LMR parameters on the first postoperative day and the difference between the NMR values on the first post-transplant day and the first pre-transplant day are predictive factors associated with the risk of DGF.

Systemic Immune Inflammation Index as a Key Predictor of Dialysis in Pediatric Chronic Kidney Disease with the Use of Random Forest Classifier

BACKGROUND

Low-grade inflammation is a significant component of chronic kidney disease (CKD). Systemic immune inflammation index (SII), a newly defined ratio combining neutrophil, lymphocyte, and platelet counts, has not yet been evaluated in the pediatric CKD population nor in the context of CKD progression or dialysis. Thus, this study aimed to analyze the complete blood cell count (CBC)-driven parameters, including SII, in children with CKD and to assess their potential usefulness in the prediction of the need for chronic dialysis.

METHODS

A single-center, retrospective study was conducted on 27 predialysis children with CKD stages 4-5 and 39 children on chronic dialysis. The data were analyzed with the artificial intelligence tools.

RESULTS

The Random Forest Classifier (RFC) model with the input variables of neutrophil count, mean platelet volume (MPV), and SII turned out to be the best predictor of the progression of pediatric CKD into end-stage kidney disease (ESKD) requiring dialysis. Out of these variables, SII showed the largest share in the prediction of the need for renal replacement therapy.

CONCLUSIONS

Chronic inflammation plays a pivotal role in the progression of CKD into ESKD. Among CBC-driven ratios, SII seems to be the most useful predictor of the need for chronic dialysis in CKD children.

A decision support system based on artificial intelligence and systems biology for the simulation of pancreatic cancer patient status

Oncology treatments require continuous individual adjustment based on the measurement of multiple clinical parameters. Prediction tools exploiting the patterns present in the clinical data could be used to assist decision making and ease the burden associated to the interpretation of all these parameters. The goal of this study was to predict the evolution of patients with pancreatic cancer at their next visit using information routinely recorded in health records, providing a decision-support system for clinicians. We selected hematological variables as the visit's clinical outcomes, under the assumption that they can be predictive of the evolution of the patient. Multivariate models based on regression trees were generated to predict next-visit values for each of the clinical outcomes selected, based on the longitudinal clinical data as well as on molecular data sets streaming from in silico simulations of individual patient status at each visit. The models predict, with a mean prediction score (balanced accuracy) of 0.79, the evolution trends of eosinophils, leukocytes, monocytes, and platelets. Time span between visits and neutropenia were among the most common factors contributing to the predicted evolution. The inclusion of molecular variables from the systems-biology in silico simulations provided a molecular background for the observed variations in the selected outcome variables, mostly in relation to the regulation of hematopoiesis. In spite of its limitations, this study serves as a proof of concept for the application of next-visit prediction tools in real-world settings, even when available data sets are small.

Anti-staphylococcus aureus adaptive immunity is impaired in end-stage renal disease patients on hemodialysis: one-year longitudinal study

Introduction

Patients with end-stage renal disease (ESRD) display defects in adaptive and innate immunity, increasing susceptibility to infection. Staphylococcus aureus (S. aureus) is a major cause of bacteraemia in this population and is associated with increased mortality. More information on the immune response to S. aureus in these patients is needed to inform effective vaccine development.

Methods

A longitudinal prospective study was carried out at two medical centers and included 48 ESRD patients who started chronic hemodialysis (HD) treatment ≤3 months before inclusion. Control samples were taken from 62 consenting healthy blood donors. Blood samples were obtained from ESRD patients at each visit, on month (M) 0 (beginning of HD), M6 and M12. Around 50 immunological markers of adaptive and innate immunity were assessed to compare immune responses to S. aureus in ESRD patients versus controls to document the changes on their immune profile during HD.

Results

S. aureus survival in whole blood was significantly higher in ESRD patients than in controls at M0 (P=0.049), while impaired oxidative burst activity was observed in ESRD patients at all timepoints (P<0.001). S. aureus-specific immunoglobulin G (IgG) responses to iron surface determinant B (IsdB) and S. aureus α hemolysin (Hla) antigens were lower in ESRD patients than in healthy donors at M0 (P=0.003 and P=0.007, respectively) and M6 (P=0.05 and P=0.03, respectively), but were restored to control levels at M12. Moreover, S. aureus-specific T-helper cell responses were comparable to controls for IsdB but were impaired for Hla antigen at all timepoints: 10% of ESRD patients responded to Hla at M0, increasing to 30% at M12, compared with 45% of healthy donors. B-cell and T-cell concentrations in blood were significantly reduced (by 60% and 40%, respectively) compared with healthy controls. Finally, upregulation of Human Leucocyte Antigen-DR (HLA-DR) and C-C chemokine Receptor type 2 (CCR2) was impaired at M0 but was restored during the first year of HD.

Conclusion

All together, these results show that adaptive immunity was largely impaired in ESRD patients, whereas innate immunity was less impacted and tended to be restored by HD.

Chronic Kidney Disease Is Characterized by Expansion of a Distinct Proinflammatory Intermediate Monocyte Subtype and by Increased Monocyte Adhesion to Endothelial Cells

SIGNIFICANCE STATEMENT

CKD is accompanied by abnormal inflammation, which contributes to progressive loss of functional renal tissue and accelerated cardiovascular disease. Although studies have documented that dysregulation of monocyte maturation and function is associated with CKD and its complications, it is not well characterized. This study reveals that a distinctive human monocyte subtype with high propensity for releasing proinflammatory mediators and activating endothelial cells is increased in adults with CKD compared with adults with high cardiovascular risk and normal kidney function. It also demonstrates that human monocyte adhesion to endothelial layers and responses to specific inflammatory migration signals are enhanced in CKD. These findings offer insights into the mechanisms of CKD-associated intravascular and localized inflammation and may suggest potential targets for therapeutic interventions.

BACKGROUND

Cardiovascular disease (CVD) in patients with CKD is associated with increased circulating intermediate monocytes (IMs). Dysregulation of monocyte maturation and function is associated with CKD and its complications, but it is incompletely characterized.

METHODS

To explore monocyte repertoire abnormalities in CKD, we studied properties of monocyte subpopulations, including IM subpopulations distinguished by HLA-DR expression level, in individuals with or without CKD. Using flow cytometry, we profiled monocyte populations in blood samples from adults with CKD, healthy volunteers (HVs), and patient controls (PCs) with high CVD risk. Monocyte subpopulations were also derived from single-cell RNA-sequencing profiles of paired blood and biopsy samples from kidney transplant recipients. We quantified intracellular cytokine production, migration, and endothelial adhesion in ex vivo assays of PBMCs.

RESULTS

Of four predefined blood monocyte subpopulations, only HLA-DR hi IMs were increased in individuals with CKD compared with HVs and PCs. In HVs and patients with CKD, LPS-stimulated HLA-DR hi IMs isolated from blood produced higher amounts of TNF and IL-1 β than other monocyte populations. Single-cell analysis revealed four monocyte clusters common to blood and kidneys, including an HLA-DR hi IM-like cluster that was enriched in kidneys versus blood. Migration toward CCL5 and CX3CL1 and adhesion to primary endothelial cell layers were increased in monocyte subpopulations in individuals with CKD compared with HVs. Monocyte adhesion to endothelial cells was partly dependent on CX3CR1/CX3CL1 interaction.

CONCLUSIONS

CKD is associated with an increased number of a distinctive proinflammatory IM subpopulation and abnormalities of monocyte migration and endothelial adhesion. Dysregulated monocyte maturation and function may represent targetable factors contributing to accelerated CVD in CKD.

Plasma Galectin-9 Is a Useful Biomarker for Predicting Renal Function in Patients Undergoing Native Kidney Biopsy

CONTEXT.—

Galectin-9 reduces tissue damage in certain immune-mediated glomerular diseases. However, its role in structural and functional renal changes in patients with varying types of chronic kidney disease (CKD) is less clear.

OBJECTIVE.—

To investigate the association between plasma galectin-9 levels, proteinuria, tubulointerstitial lesions, and renal function in different CKD stages.

DESIGN.—

We measured plasma galectin-9 levels in 243 patients undergoing renal biopsy for determining the CKD etiology. mRNA and protein expression levels of intrarenal galectin-9 were assessed by quantitative real-time polymerase chain reaction and immunostaining. Relationships between plasma galectin-9, clinical characteristics, and tubulointerstitial damage were analyzed with logistic regression. We investigated galectin-9 expression patterns in vitro in murine J774 macrophages treated with differing stimuli.

RESULTS.—

To analyze the relationship between galectin-9 and clinical features, we divided the patients into 2 groups according to median plasma galectin-9 levels. The high galectin-9 group tended to be older and to have decreased renal function, higher proteinuria, and greater interstitial fibrosis. After multivariable adjustment, elevated plasma galectin-9 levels were independently associated with stage 3b or higher CKD. An analysis of gene expression in the tubulointerstitial compartment in the biopsy samples showed a significant positive correlation between intrarenal galectin-9 mRNA expression and plasma galectin-9 levels. Immunohistochemistry confirmed increased galectin-9 expression in the renal interstitium of patients with advanced CKD, and most galectin-9-positive cells were macrophages, as determined by double-immunofluorescence staining. In vitro experiments showed that galectin-9 expression in macrophages was significantly increased after interferon-γ stimulation.

CONCLUSIONS.—

Our findings suggest that plasma galectin-9 is a good biomarker for diagnosing advanced CKD.

Risks and burdens of incident dyslipidaemia in long COVID: a cohort study

BACKGROUND

Non-clinical evidence and a few human studies with short follow-ups suggest increased risk of dyslipidaemia in the post-acute phase of COVID-19 (ie, >30 days after SARS-CoV-2 infection). However, detailed large-scale controlled studies with longer follow-ups and in-depth assessment of the risks and burdens of incident dyslipidaemia in the post-acute phase of COVID-19 are not yet available. We, therefore, aimed to examine the risks and 1-year burdens of incident dyslipidaemia in the post-acute phase of COVID-19 among people who survive the first 30 days of SARS-CoV-2 infection.

METHODS

In this cohort study, we used the national health-care databases of the US Department of Veterans Affairs to build a cohort of 51 919 participants who had a positive COVID-19 test and survived the first 30 days of infection between March 1, 2020, and Jan 15, 2021; a non-infected contemporary control group (n=2 647 654) that enrolled patients between March 1, 2020, and Jan 15, 2021; and a historical control group (n=2 539 941) that enrolled patients between March 1, 2018, and Jan 15, 2019. Control groups had no evidence of SARS-CoV-2 infection, and participants in all three cohorts were free of dyslipidaemia before cohort enrolment. We then used inverse probability weighting using predefined and algorithmically-selected high dimensional variables to estimate the risks and 1-year burdens of incident dyslipidaemia, lipid-lowering medications use, and a composite of these outcomes. We reported two measures of risk: hazard ratios (HRs) and burden per 1000 people at 12 months. Additionally, we estimated the risks and burdens of incident dyslipidaemia outcomes in mutually exclusive groups based on the care setting of the acute infection (ie, participants who were non-hospitalised, hospitalised, or admitted to intensive care during the acute phase of SARS-CoV-2 infection).

FINDINGS

In the post-acute phase of the SARS-CoV-2 infection, compared with the non-infected contemporary control group, those in the COVID-19 group had higher risks and burdens of incident dyslipidaemia, including total cholesterol greater than 200 mg/dL (hazard ratio [HR] 1·26, 95% CI 1·22-1·29; burden 22·46, 95% CI 19·14-25·87 per 1000 people at 1 year), triglycerides greater than 150 mg/dL (1·27, 1·23-1·31; 22·03, 18·85-25·30), LDL cholesterol greater than 130 mg/dL (1·24, 1·20-1·29; 18·00, 14·98-21·11), and HDL cholesterol lower than 40 mg/dL (1·20, 1·16-1·25; 15·58, 12·52-18·73). The risk and burden of a composite of these abnormal lipid laboratory outcomes were 1·24 (95% CI 1·21-1·27) and 39·19 (95% CI 34·71-43·73), respectively. There was also increased risk and burden of incident lipid-lowering medications use (HR 1·54, 95% CI 1·48-1·61; burden 25·50, 95% CI 22·61-28·50). A composite of any dyslipidaemia outcome (laboratory abnormality or lipid-lowering medications use) yielded an HR of 1·31 (95% CI 1·28-1·34) and a burden of 54·03 (95% CI 49·21-58·92). The risks and burdens of these post-acute outcomes increased in a graded fashion corresponding to the severity of the acute phase of COVID-19 infection (ie, whether patients were non-hospitalised, hospitalised, or admitted to intensive care). The results were consistent in analyses comparing the COVID-19 group to the non-infected historical control group.

INTERPRETATION

Our findings suggest increased risks and 1-year burdens of incident dyslipidaemia and incident lipid-lowering medications use in the post-acute phase of COVID-19 infection. Post-acute care for those with COVID-19 should involve attention to dyslipidaemia as a potential post-acute sequela of SARS-CoV-2 infection.

FUNDING

US Department of Veterans Affairs.

Association of cumulative monocyte to high-density lipoprotein ratio with the risk of type 2 diabetes: a prospective cohort study

BACKGROUND

Recent studies have established that monocyte-derived inflammation plays a central role in the pathogenesis of type 2 diabetes mellitus (T2DM). It is unclear whether chronic metabolic inflammation, reflected by the cumulative monocyte to high-density lipoprotein ratio (CumMHR), predisposes the general population to T2DM.

METHODS

This study included 40,813 participants without diabetes from a real-life, community-based cohort (the Kailuan Study) attending a 2-year cycle of health survey since 2006. Cumulative exposure was obtained from 2006/2007 to 2010/2011. Follow-up started at 2010/2011 and through 2020. Multivariable-adjusted Cox regression models were used to calculate the CumMHR-associated risk of incident T2DM.

RESULTS

Over a median follow-up period of 7.98 (IQR: 5.74-8.87) years, 4,848 T2DM cases occurred. The CumMHR was positively associated with the risk of incident T2DM after adjusting for age, sex, smoking, drinking habits, physical activities, BMI, triglyceride-glycemia index, log(leukocyte count), log(hsCRP), blood pressure, renal function, and medication uses with adjusted HRs of 1.0 (ref.), 1.18 (1.05‒1.25), 1.17 (1.07‒1.27), 1.38 (1.26‒1.50), respectively, in CumMHR Quartiles 1, 2, 3 and 4. When follow-up ended at 2014/2015, the short-term (4‒year) adjusted T2DM risks in CumMHR Quartiles 2, 3, and 4 were 1.14 (1.01‒1.29), 1.17 (1.04‒1.32), 1.40 (1.25‒1.58), respectively, relative to Quartile 1. A significant interaction between CumMHR and cumulative high-sensitivity C-reactive protein (CumCRP) was observed (P-interaction: 0.0109). The diabetic risk in the highest quartile of CumMHR was higher (1.53 [1.28‒1.84]) when CumCRP < 1 mg/L, attenuated with increasing CumCRP levels (1 ~ 10 mg/L) and disappeared in CumCRP ≥ 10 mg/L. Hypertension, overweight, or smoking habits further modified the CumMHR-associated diabetic risk.

CONCLUSIONS

Cumulative MHR may be a promising supplement to hsCRP for more comprehensively assessing the influence of metabolic inflammation on T2DM susceptibility. For primary prevention, targeting high CumMHR, especially in cases at low risk of diabetes defined by traditional risk factors, may further help reduce the diabetic risk.

Particulate matter of air pollution may increase risk of kidney failure in IgA nephropathy

IgA nephropathy (IgAN) is characterized by deposition of galactose-deficient IgA1 (Gd-IgA1) in glomerular mesangium associated with mucosal immune disorders. Since environmental pollution has been associated with the progression of chronic kidney disease in the general population, we specifically investigated the influence of exposure to fine particulate matter less than 2.5 μm in diameter (PM2.5) on IgAN progression. Patients with biopsy-proven primary IgAN were recruited from seven Chinese kidney centers. PM2.5 exposure from 1998 to 2016 was derived from satellite aerosol optical depth data and a total of 1,979 patients with IgAN, including 994 males were enrolled. The PM2.5 exposure levels for patients from different provinces varied but, in general, the PM2.5 exposure levels among patients from the north were higher than those among patients from the south. The severity of PM2.5 exposure in different regions was correlated with regional kidney failure burden. In addition, each 10 μg/m³ increase in annual average concentration of PM2.5 exposure before study entry (Hazard Ratio, 1.14; 95% confidence interval, 1.06-1.22) or time-varying PM2.5 exposure after study entry (1.10; 1.01-1.18) were associated with increased kidney failure risk after adjustment for age, gender, estimated glomerular filtration rate, urine protein, uric acid, hemoglobin, mean arterial pressure, Oxford classification, glucocorticoid and renin-angiotensin system blocker therapy. The associations were robust when the time period, risk factors of cardiovascular diseases or city size were further adjusted on the basis of the above model. Thus, our results suggest that PM2.5 is an independent risk factor for kidney failure in patients with IgAN, but these findings will require validation in more diverse populations and other geographic regions.

High Macrophage Densities in Native Kidney Biopsies Correlate With Renal Dysfunction and Promote ESRD

Introduction

Macrophages and monocytes are main players in innate immunity. The relevance of mononuclear phagocyte infiltrates on clinical outcomes remains to be determined in native kidney diseases.

Methods

Our cross-sectional study included 324 patients with diagnostic renal biopsies comprising 17 disease entities and normal renal tissues for comparison. All samples were stained for CD68⁺ macrophages. Selected groups were further subtyped for CD14⁺ monocytes and CD163⁺ alternatively activated macrophages. Using precise pixel-based digital measurements, we quantified cell densities as positively stained areas in renal cortex and medulla as well as whole renal tissue. Laboratory and clinical data of all cases at the time of biopsy and additional follow-up data in 158 cases were accessible.

Results

Biopsies with renal disease consistently revealed higher CD68⁺-macrophage densities and CD163⁺-macrophage densities in cortex and medulla compared to controls. High macrophage densities correlated with impaired renal function at biopsy and at follow-up in all diseases and in diseases analyzed separately. High cortical CD68⁺-macrophage densities preceded shorter renal survival, defined as requirement of permanent dialysis. CD14⁺ monocyte densities showed no difference compared to controls and did not correlate with renal function.

Conclusion

Precise quantification of macrophage densities in renal biopsies may contribute to risk stratification to identify patients with high risk for end-stage renal disease (ESRD) and might be a promising therapeutic target in renal disease.

Impact of monocyte-related modulators and kidney function on mortality in hospitalized patients with COVID-19

Patients with chronic kidney disease (CKD) are at high risk of severe complications from COVID-19 and functional monocyte disturbances have been implicated to play a role. Our objective was to analyse the association between kidney function and monocyte modulatory factors, with risk of mortality in patients with COVID-19. Hospitalized patients with COVID-19 (n = 110) were included and in-hospital mortality was analysed with unadjusted and adjusted multiple logistic regression analysis. Plasma levels of monocyte chemoattractant factors (MIP-1α, MCP-1, IL-6) and a monocyte immune modulator (sCD14) were analysed and correlated to kidney function and risk of mortality. Monocyte modulatory factors were also determined in CKD patients without infection (disease controls) and in healthy subjects. Patients who died in hospital were more often in CKD stages 3-5, with lower estimated glomerular filtration rate (eGFR) and had significantly higher MIP-1α and IL-6 levels than survivors. In multiple regression analyses adjusted for age, sex and eGFR, both high MCP-1 and high MIP-1α were significantly associated with risk of in-hospital mortality. Apart from impaired kidney function, also the concentrations of MCP-1 and MIP-1α add important prognostic information in hospitalized patients with COVID-19. These data provide an increased understanding of the impact of monocyte modulators in patients with COVID-19 and normal or impaired kidney function, and warrant consideration in the pursuit of new effective therapies.

GDF-15 and sST-2 act as biomarkers of disease severity but not independent predictors in idiopathic membranous nephropathy

BACKGROUND

We aimed to explore biomarkers of disease severity in idiopathic membranous nephropathy (IMN) and independent predictors of prognosis in IMN.

METHODS

Clinical data were collected from 79 IMN patients. Serum levels of growth differentiation factor-15 (GDF-15) and soluble suppression of tumorigenicity (sST-2) were tested by enzyme-linked immunosorbent assay (ELISA) in IMN patients and subgroups, and correlation analysis was performed. Univariate and multiple logistic regression analyses were performed to identify independent predictors of IMN, and a combined-factors model was constructed. Moreover, the area under the receiver operating characteristic (ROC) curve (AUC) was used to evaluate the prognostic efficacy.

RESULTS

The levels of GDF-15 were significantly higher in the IMN group and subgroups with low estimated glomerular filtration rate (eGFR) and high 24 hour-urine protein (24 h-UP), whiles sST-2 level was only significantly higher in the IMN group. GDF-15 levels were positively correlated with creatinine (Crea), cystatin C (Cys-C) and 24 h-UP and negatively correlated with GFR and albumin (Alb), while sST-2 levels were positively correlated with Urea and Cys-C and negatively correlated with eGFR. After one year of follow-up, 54 patients had incomplete remission. Serum phospholipase A2 receptor antibody (PLA2R-Ab), Urea, high-density lipoprotein cholesterol (HDL-C) and 24 h-UP but not GDF-15 and sST2 were independent predictors of prognosis in IMN patients, but combined factors showed the best prognostic efficacy.

CONCLUSION

Serum levels of GDF-15 and sST-2 may be potential biomarkers for the severity of IMN, while the combined-factors model is effective for predicting the risk factors of incomplete remission in IMN.

Risks and burdens of incident diabetes in long COVID: a cohort study

BACKGROUND

There is growing evidence suggesting that beyond the acute phase of SARS-CoV-2 infection, people with COVID-19 could experience a wide range of post-acute sequelae, including diabetes. However, the risks and burdens of diabetes in the post-acute phase of the disease have not yet been comprehensively characterised. To address this knowledge gap, we aimed to examine the post-acute risk and burden of incident diabetes in people who survived the first 30 days of SARS-CoV-2 infection.

METHODS

In this cohort study, we used the national databases of the US Department of Veterans Affairs to build a cohort of 181 280 participants who had a positive COVID-19 test between March 1, 2020, and Sept 30, 2021, and survived the first 30 days of COVID-19; a contemporary control (n=4 118 441) that enrolled participants between March 1, 2020, and Sept 30, 2021; and a historical control (n=4 286 911) that enrolled participants between March 1, 2018, and Sept 30, 2019. Both control groups had no evidence of SARS-CoV-2 infection. Participants in all three comparison groups were free of diabetes before cohort entry and were followed up for a median of 352 days (IQR 245-406). We used inverse probability weighted survival analyses, including predefined and algorithmically selected high dimensional variables, to estimate post-acute COVID-19 risks of incident diabetes, antihyperglycaemic use, and a composite of the two outcomes. We reported two measures of risk: hazard ratio (HR) and burden per 1000 people at 12 months.

FINDINGS

In the post-acute phase of the disease, compared with the contemporary control group, people with COVID-19 exhibited an increased risk (HR 1·40, 95% CI 1·36-1·44) and excess burden (13·46, 95% CI 12·11-14·84, per 1000 people at 12 months) of incident diabetes; and an increased risk (1·85, 1·78-1·92) and excess burden (12·35, 11·36-13·38) of incident antihyperglycaemic use. Additionally, analyses to estimate the risk of a composite endpoint of incident diabetes or antihyperglycaemic use yielded a HR of 1·46 (95% CI 1·43-1·50) and an excess burden of 18·03 (95% CI 16·59-19·51) per 1000 people at 12 months. Risks and burdens of post-acute outcomes increased in a graded fashion according to the severity of the acute phase of COVID-19 (whether patients were non-hospitalised, hospitalised, or admitted to intensive care). All the results were consistent in analyses using the historical control as the reference category.

INTERPRETATION

In the post-acute phase, we report increased risks and 12-month burdens of incident diabetes and antihyperglycaemic use in people with COVID-19 compared with a contemporary control group of people who were enrolled during the same period and had not contracted SARS-CoV-2, and a historical control group from a pre-pandemic era. Post-acute COVID-19 care should involve identification and management of diabetes.

FUNDING

US Department of Veterans Affairs and the American Society of Nephrology.

Is White Blood Cell Count Associated With Mortality in Peritoneal Dialysis Patients?: A Retrospective Single-Center Analysis

Objective

White blood cell (WBC) count was used as a predictor in researches since it is a prognostic indicator and a substantial predictor of the development of cardiovascular disease (CVD). There have been very few reports looking at the association between WBC count and overall mortality in peritoneal dialysis (PD) patients. We intended to explore if the baseline total leukocyte count is linked to all-cause mortality, considering the association for linearity in PD patients.

Material and methods

The study comprised 204 incident PD patients who began treatment at the Nephrology Department of Health Sciences University, Kayseri Medical Faculty, Kayseri City Hospital between January 2009 and December 2017. The research period ended in January 2018. The link between baseline WBC count and all-cause mortality was studied using Cox proportional hazards models.

Results

The average age of the patients was 46.75 (8.49) years, and 48.5% were male. Diabetes and hypertension were prevalent in 59.8% and 76% of the population, respectively. The average WBC count was 9.37 (2.70) × 10³/µL. The mortality risk increased by 23% for every one-unit increase in the crude model. The hazard of death in the fully corrected model was 1.12 [95% confidence interval (CI): 1.02-1.23, p = 0.015]. In the models with WBC count stratified by tertiles, the mortality hazard of patients in tertile 2 was 2.38 (95% CI: 1.24-4.58, p = 0.009) and of patients in tertile 3 in the fully adjusted model was 2.64 (95% CI: 1.30-5.33, p = 0.007), compared with patients in tertile 1.

Conclusion

The initial WBC count may have a long-term impact on patient survival. Individuals with higher basal values or even an elevation in follow-up should therefore be strictly controlled, and all preventative measures should be made to lower the risk level.

Increased Monocyte/Lymphocyte Ratio as Risk Marker for Cardiovascular Events and Infectious Disease Hospitalization in Dialysis Patients

Introduction

In dialysis patients, cardiovascular disease (CVD) and infectious disease contribute to poor clinical outcomes. We investigated if a higher monocyte/lymphocyte ratio (MLR) is associated with an increased risk of CVD events and infectious disease hospitalizations in incident dialysis patients.

Methods

In an ongoing observational prospective cohort study, 132 Japanese dialysis patients (age 58.7 ± 11.7 years; 70% men) starting dialysis therapy were enrolled and followed up for a median of 48.7 months. Laboratory biomarkers, including white blood cell count and its differential count, were determined at baseline. Event-free time and relative risks (RRs) were calculated using the Kaplan-Meier curves and Cox models, respectively.

Results

When divided into 2 groups according to median MLR (0.35 [range, 0.27–0.46]), the periods without CVD events were significantly shorter in the high MLR group than in the low MLR group (log-rank test = 5.60, p = 0.018). The RR of CVD events, after adjusting for age, sex, and diabetes, was 2.43 (1.22–4.84) in the high MLR group compared to the low MLR group. The periods without infections requiring hospitalization were also shorter (log-rank test = 4.16, p = 0.041). The RR of infections requiring hospitalization was 1.98 (1.02–3.83) after the same adjustments. The number of CVD events was higher in the high MLR group (18.6 events per 100 person-years at risk [pyr]) than the low MLR group (11.1 events per 100 pyr). The duration of infectious disease hospitalization was longer in the high MLR group (6.3 days per pyr) than in the low MLR group (2.8 days per pyr).

Conclusion

A higher MLR is associated with increased risks of both CVD events and infectious disease hospitalization in dialysis patients.

Kidney Outcomes in Long COVID

BACKGROUND

COVID-19 is associated with increased risk of post-acute sequelae involving pulmonary and extrapulmonary organ systems-referred to as long COVID. However, a detailed assessment of kidney outcomes in long COVID is not yet available.

METHODS

We built a cohort of 1,726,683 US Veterans identified from March 1, 2020 to March 15, 2021, including 89,216 patients who were 30-day survivors of COVID-19 and 1,637,467 non-infected controls. We examined risks of AKI, eGFR decline, ESKD, and major adverse kidney events (MAKE). MAKE was defined as eGFR decline ≥50%, ESKD, or all-cause mortality. We used inverse probability-weighted survival regression, adjusting for predefined demographic and health characteristics, and algorithmically selected high-dimensional covariates, including diagnoses, medications, and laboratory tests. Linear mixed models characterized intra-individual eGFR trajectory.

RESULTS

Beyond the acute illness, 30-day survivors of COVID-19 exhibited a higher risk of AKI (aHR, 1.94; 95% CI, 1.86 to 2.04), eGFR decline ≥30% (aHR, 1.25; 95% CI, 1.14 to 1.37), eGFR decline ≥40% (aHR, 1.44; 95% CI, 1.37 to 1.51), eGFR decline ≥50% (aHR, 1.62; 95% CI, 1.51 to 1.74), ESKD (aHR, 2.96; 95% CI, 2.49 to 3.51), and MAKE (aHR, 1.66; 95% CI, 1.58 to 1.74). Increase in risks of post-acute kidney outcomes was graded according to the severity of the acute infection (whether patients were non-hospitalized, hospitalized, or admitted to intensive care). Compared with non-infected controls, 30-day survivors of COVID-19 exhibited excess eGFR decline (95% CI) of -3.26 (-3.58 to -2.94), -5.20 (-6.24 to -4.16), and -7.69 (-8.27 to -7.12) ml/min per 1.73 m² per year, respectively, in non-hospitalized, hospitalized, and those admitted to intensive care during the acute phase of COVID-19 infection.

CONCLUSIONS

Patients who survived COVID-19 exhibited increased risk of kidney outcomes in the post-acute phase of the disease. Post-acute COVID-19 care should include attention to kidney disease.

The prognostic value of peripheral total and differential leukocyte count in renal progression: A community-based study

Background

Systemic inflammation is related to chronic kidney disease (CKD) patients. Elevated peripheral leukocyte count may be a herald of increased systemic inflammation and subclinical disease. Inflammation plays an important role in renal progression. The pattern of total and differential leukocyte count in CKD is not well understood. Besides, the association between total and differential leukocyte count and renal progression is still uncertain.

Methods

We conducted a community-based cohort study with a follow-up period of two years to evaluate the total and differential leukocyte counts and renal progression association.

Results

In our study population from the community with a total number of 2128, we found 15.7% (335/2128) CKD patients with a mean estimated glomerular filtration rate (eGFR) around 96 ± 26 ml/min/1.73 m². The peripheral total leukocyte count and also differential leukocyte count were significantly negatively correlated with eGFR. A total of 56 patients (3%) experienced a rapid progression of the kidney with the definition of eGFR reduction changes of 30% or greater within two years. Univariate analysis indicated that rapid renal progression was significantly associated with male gender, co-morbidity of diabetes mellitus (DM), higher uric acid levels, higher peripheral neutrophil, monocyte, and eosinophil counts. However, only the peripheral neutrophil count was positively and independently associated with rapid renal progression after multivariate analysis. The ROC curve analysis found that the optimal cutoff value of peripheral neutrophil count for rapid progression was 2760/ mm³, with an area under the curve of 0.813.

Conclusion

Hyperinflammation with higher peripheral total and differential leukocyte count was noted in CKD patients. The peripheral neutrophil count was the only independent factor significantly associated with rapid renal progression. The optimal cutoff point of the peripheral neutrophil count with 2760/mm³ is useful for determining the high-risk population for rapid renal progression with a satisfying sensitivity and specificity.

Temporal trends of COVID-19 mortality and hospitalisation rates: an observational cohort study from the US Department of Veterans Affairs

OBJECTIVES

To investigate the temporal trends of 30-day mortality and hospitalisation in US Veterans with COVID-19 and 30-day mortality in hospitalised veterans with COVID-19 and to decompose the contribution of changes in the underlying characteristics of affected populations to these temporal changes.

DESIGN

Observational cohort study.

SETTING

US Department of Veterans Affairs.

PARTICIPANTS

49 238 US veterans with a positive COVID-19 test between 20 March 2020 and 19 September 2020; and 9428 US veterans hospitalised with a positive COVID-19 test during the same period.

OUTCOME MEASURES

30-day mortality rate and hospitalisation rate.

RESULTS

Between 20 March 2020 and 19 September 2020 and in COVID-19 positive individuals, 30-day mortality rate dropped by 9.2% from 13.6% to 4.4%; hospitalisation rate dropped by 16.8% from 33.8% to 17.0%. In hospitalised COVID-19 individuals, 30-day mortality rate dropped by 12.7% from 23.5% to 10.8%. Among COVID-19 positive individuals, decomposition analyses suggested that changes in demographic, health and contextual characteristics, COVID-19 testing capacity, and hospital occupancy rates accounted for 40.2% and 33.3% of the decline in 30-day mortality and hospitalisation, respectively. Changes in the underlying characteristics of hospitalised COVID-19 individuals accounted for 29.9% of the decline in 30-day mortality.

CONCLUSION

Between March and September 2020, changes in demographic and health characteristics of people infected with COVID-19 contributed measurably to the substantial decline in 30-day mortality and hospitalisation.

Relationship between Monocytes and Stenosis-Related Autologous Arteriovenous Fistula Dysfunction

BACKGROUND

Arteriovenous fistula (AVF) is considered to be the best choice of vascular access, but the maturation rate and patency rate of AVF are not satisfactory. Many studies have explored the influencing factors of AVF failure but do not involve the direct relationship between monocyte count and AVF failure. This study aims to explore the relationship between monocyte count and AVF dysfunction related to stenosis.

METHODS

From September 2017 to September 2018, basic clinical data and laboratory parameters of patients were collected. All included patients were followed up to September 2019. The stenosis-related AVF failure events that occurred after the patient included in the study and the time of their occurrence were recorded. All patients were divided into 3 groups based on the tertile of monocyte count. Kaplan-Meier method was used to compare the patency rate of AVF in each group. The effects of variables on AVF failure were analyzed. A multivariate Cox regression model with p < 0.05 was included in the univariate Cox regression analysis.

RESULTS

A total of 120 patients were included in this study. According to the recorded baseline monocyte count levels, they were divided into 3 groups according to their tertiles, 34 cases in the T1 group (T1 < 0.32 × 109/L), 44 cases in the T2 group (0.32 ≤ T2 < 0.51 × 109/L), and 42 cases in T3 group (T3 ≥0.51 × 109/L). After a median follow-up of 20 months, a total of 31 AVF failure events occurred. Kaplan-Meier survival curves showed that patients with a baseline monocyte count ≥0.51 × 109/L had the lowest patency rate of AVF (log-rank test χ2 = 7.525, p = 0.023). After adjusting to basic clinical data and biochemical indicators, there were statistically significant differences in patency rates of the 3 groups (hazard ratio = 2.774, 95% CI = 1.092-7.043).

CONCLUSION

Monocyte count ≥0.51 × 109/L is an independent risk factor for AVF failure, and AVF failure caused by monocytes may be driven by inflammation.

Monocyte to HDL ratio: a novel marker of resistant hypertension in CKD patients

BACKGROUND

Inflammation, oxidative stress (OS), atherosclerosis and resistant hypertension (RH) are common features of chronic kidney disease (CKD) leading to a higher risk of death from cardiovascular disease. These effects seem to be modulated by impaired anti-oxidant, anti-inflammatory and reverse cholesterol transport actions of high-density lipoprotein cholesterol (HDL). HDL prevents and reverses monocyte recruitment and activation into the arterial wall and impairs endothelial adhesion molecule expression. Recently, monocyte count to HDL-cholesterol ratio (MHR) has emerged as a potential marker of inflammation and OS, demonstrating to be relevant in CKD. Our research was aimed to assess, for the first time, its reliability in RH.

METHODS

We performed a retrospective study on 214 patients with CKD and arterial hypertension who were admitted between January and June 2019 to our Department, 72 of whom were diagnosed with RH.

RESULTS

MHR appeared inversely related to eGFR (ρ = - 0.163; P = 0.0172). MHR was significantly higher among RH patients compared to non-RH ones (12.39 [IQR 10.67-16.05] versus 7.30 [5.49-9.06]; P < 0.0001). Moreover, MHR was significantly different according to the number of anti-hypertensive drugs per patient in the whole study cohort (F = 46.723; P < 0.001) as well as in the non-RH group (F = 14.191; P < 0.001). Moreover, MHR positively correlates with diabetes mellitus (ρ = 0.253; P = 0.0002), white blood cells (ρ = 0.664; P < 0.0001) and C-reactive protein (ρ = 0.563; P < 0.0001).

CONCLUSIONS

MHR may be a reliable biomarker due to the connection between HDL and monocytes. Our study suggests that MHR is linked with the use of multiple anti-hypertensive therapy and resistant hypertension in CKD patients, and can be a useful ratio to implement appropriate treatment strategies.

Myeloid cell-derived coagulation tissue factor is associated with renal tubular damage in mice fed an adenine diet

Patients with chronic kidney disease (CKD) commonly exhibit hypercoagulability. Increased levels of uremic toxins cause thrombogenicity by increasing tissue factor (TF) expression and activating the extrinsic coagulation cascade. TF is induced in monocytes and macrophages under pathological conditions, such as inflammatory diseases. However, the role of monocyte myeloid cell TF in CKD progression remains unclear. We aimed to clarify this issue, and the present study found that patients with CKD had elevated levels of D-dimer, a marker of fibrin degradation, which was associated with decreased estimated glomerular filtration rate and increased serum levels of uremic toxins, such as indoxyl sulfate. In vitro studies showed that several uremic toxins increased cellular TF levels in monocytic THP-1 cells. Mice with TF specifically deleted in myeloid cells were fed an adenine diet to cause uremic kidney injury. Myeloid TF deletion reduced tubular injury and pro-inflammatory gene expression in the kidneys of adenine-induced CKD but did not improve renal function as measured by plasma creatinine or blood urea nitrogen. Collectively, our findings suggest a novel concept of pathogenesis of coagulation-mediated kidney injury, in which elevated TF levels in monocytes under uremic conditions is partly involved in the development of CKD.

Serum Albumin Modifies the Effect of Peripheral Blood Monocytes on Severity of Diabetic Nephropathy in an Adult Population

BACKGROUND

Our aim in this study was to characterize clinical associations between peripheral blood immune populations and diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus.

METHODS

We queried hospital records from an outpatient diabetes primary care clinic between 2018 and 2019 for clinical and laboratory data, including complete blood counts with differentials, serum albumin and globulin, glycated hemoglobin (A1C) and urine albumin-to-creatinine ratio. One hundred ninety-eight patients had complete cross-sectional data with temporally proximate complete blood counts and urine albumin-to-creatinine ratios. After univariable correlation assessment, we used a forward multivariable linear regression model to test the hypothesis that higher numbers of circulating innate immune populations would be associated with DKD, while accounting for known demographic, clinical and laboratory risk factors. We defined DKD as an albumin-to-creatinine ratio of >3 mg/mmol or an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m² from the Chronic Kidney Disease Epidemiology Collaboration.

RESULTS

Adjusted analyses demonstrated significant (p<0.01) associations between higher urine albumin:creatinine ratio and peripheral circulating monocytes, independent of other established significant risk factors, including blood pressure, A1C, age and sex. We also identified serum albumin as a potentially important modifying factor of albuminuric kidney disease, which interacts with monocytes in more advanced disease. In contrast, the variable most strongly predictive of eGFR was age.

CONCLUSIONS

Circulating monocytes and serum albumin are significantly associated with albuminuria, but not eGFR in DKD. These results support the potential role of the innate immune system in diabetic microvascular end-organ damage and urinary protein loss, and may be readily translatable clinical markers to incorporate into risk-assessment models for prognostication in diabetes.

Proteomic Profiling of Leukocytes Reveals Dysregulation of Adhesion and Integrin Proteins in Chronic Kidney Disease-Related Atherosclerosis

A progressive loss of functional nephrons defines chronic kidney disease (CKD). Complications related to cardiovascular disease (CVD) are the principal causes of mortality in CKD; however, the acceleration of CVD in CKD remains unresolved. Our study used a complementary proteomic approach to assess mild and advanced CKD patients with different atherosclerosis stages and two groups of patients with different classical CVD progression but without renal dysfunction. We utilized a label-free approach based on LC-MS/MS and functional bioinformatic analyses to profile CKD and CVD leukocyte proteins. We revealed dysregulation of proteins involved in different phases of leukocytes' diapedesis process that is very pronounced in CKD's advanced stage. We also showed an upregulation of apoptosis-related proteins in CKD as compared to CVD. The differential abundance of selected proteins was validated by multiple reaction monitoring, ELISA, Western blotting, and at the mRNA level by ddPCR. An increased rate of apoptosis was then functionally confirmed on the cellular level. Hence, we suggest that the disturbances in leukocyte extravasation proteins may alter cell integrity and trigger cell death, as demonstrated by flow cytometry and microscopy analyses. Our proteomics data set has been deposited to the ProteomeXchange Consortium via the PRIDE repository with the data set identifier PXD018596.

DNA Methylation Sustains "Inflamed" Memory of Peripheral Immune Cells Aggravating Kidney Inflammatory Response in Chronic Kidney Disease

The incidence of chronic kidney disease (CKD) has rapidly increased in the past decades. A progressive loss of kidney function characterizes a part of CKD even with intensive supportive treatment. Irrespective of its etiology, CKD progression is generally accompanied with the development of chronic kidney inflammation that is pathologically featured by the low-grade but chronic activation of recruited immune cells. Cumulative evidence support that aberrant DNA methylation pattern of diverse peripheral immune cells, including T cells and monocytes, is closely associated with CKD development in many chronic disease settings. The change of DNA methylation profile can sustain for a long time and affect the future genes expression in the circulating immune cells even after they migrate from the circulation into the involved kidney. It is of clinical interest to reveal the underlying mechanism of how altered DNA methylation regulates the intensity and the time length of the inflammatory response in the recruited effector cells. We and others recently demonstrated that altered DNA methylation occurs in peripheral immune cells and profoundly contributes to CKD development in systemic chronic diseases, such as diabetes and hypertension. This review will summarize the current findings about the influence of aberrant DNA methylation on circulating immune cells and how it potentially determines the outcome of CKD.

Acute Kidney Injury in a National Cohort of Hospitalized US Veterans with COVID-19

BACKGROUND AND OBJECTIVES

Coronavirus disease 2019 (COVID-19) is associated with higher risk of AKI. We aimed to describe rates and characterize predictors and health outcomes associated with AKI in a national cohort of US veterans hospitalized with COVID-19.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a cohort of 5216 US veterans hospitalized with COVID-19 identified through July 23, 2020, we described changes in serum creatinine and examined predictors of AKI and the associations between AKI, health resource utilization, and death, utilizing logistic regressions. We characterized geographic and temporal variations in AKI rates and estimated variance explained by key variables utilizing Poisson regressions.

RESULTS

In total, 1655 (32%) participants had AKI; 961 (58%), 223 (13%), and 270 (16%) met Kidney Disease Improving Global Outcomes definitions of stage 1, 2, and 3 AKI, respectively, and 201 (12%) received KRT. Eight percent of participants had AKI within 1 day of hospitalization, and 47% did not recover to baseline serum creatinine by discharge. Older age, Black race, male gender, obesity, diabetes, hypertension, and lower eGFR were significant predictors of AKI during hospitalization with COVID-19. AKI was associated with higher mechanical ventilation use (odds ratio, 6.46; 95% confidence interval, 5.52 to 7.57) and longer hospital stay (5.56 additional days; 95% confidence interval, 4.78 to 6.34). AKI was also associated with higher risk of death (odds ratio, 6.71; 95% confidence interval, 5.62 to 8.04); this association was stronger in Blacks (P value of interaction <0.001). Hospital-level rates of AKI exhibited substantial geographic variability, ranging from 10% to 56%. Between March and July 2020, AKI rates declined from 40% to 27%; proportions of AKI stage 3 and AKI requiring KRT decreased from 44% to 17%. Both geographic and temporal variabilities were predominately explained by percentages of Blacks (31% and 49%, respectively).

CONCLUSIONS

AKI is common during hospitalization with COVID-19 and associated with higher risk of health care resource utilization and death. Nearly half of patients with AKI did not recover to baseline by discharge. Substantial geographic variation and temporal decline in rates and severity of AKI were observed.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2020_11_16_CJN09610620_final.mp3.

Baseline liver function tests and full blood count indices and their association with progression of chronic kidney disease and renal outcomes in Aboriginal and Torres Strait Islander people: the eGFR follow- up study

Background

Determination of risks for chronic kidney disease (CKD) progression could improve strategies to reduce progression to ESKD. The eGFR Study recruited a cohort of adult Aboriginal and Torres Strait Islander people (Indigenous Australians) from Northern Queensland, Northern Territory and Western Australia, aiming to address the heavy CKD burden experienced within these communities.

Methods

Using data from the eGFR study, we explored the association of baseline liver function tests (LFTs) (alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT), bilirubin and albumin) and full blood count (FBC) indices (white blood cell and red blood cell counts and haemoglobin) with annual eGFR decline and renal outcomes (first of 30% decline in eGFR with a follow-up eGFR < 60 mL/min/1.73 m², initiation of renal replacement therapy, or renal death). Comparisons of baseline variables across eGFR categories were calculated using analysis of variance and logistic regression as appropriate. Linear and multivariable regression models were used to estimate the annual change in eGFR for changes in FBC indices and LFTs. Cox proportional hazard models were used to estimate the hazard ratio for developing renal outcome for changes in baseline FBC indices and LFTs.

Results

Of 547 participants, 540 had at least one baseline measure of LFTs and FBC indices. The mean age was 46.1 (14.7) years and 63.6% were female. The median follow-up was 3.1 (IQR 2.8–3.6) years. Annual decline in eGFR was associated with low serum albumin (p < 0.001) and haemoglobin (p = 0.007). After adjustment for age, gender, urine albumin/creatinine ratio, diabetes, BMI, CRP, WHR, alcohol consumption, cholesterol and triglycerides, low serum albumin (p < 0.001), haemoglobin (p = 0.012) and bilirubin (p = 0.011) were associated with annual decline in eGFR.

Renal outcomes were inversely associated with serum albumin (p < 0.001), bilirubin (p = 0.012) and haemoglobin (p < 0.001) and directly with GGT (p = 0.007) and ALP (p < 0.001). Other FBC indices and LFTs were not associated with annual decline in eGFR or renal outcomes.

Conclusions

GGT, ALP, bilirubin, albumin and haemoglobin independently associate with renal outcomes. Contrary to findings from other studies, no association was found between renal outcomes and other FBC indices. These findings may help focus strategies to prevent disease progression in this high-risk population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-020-02185-x.

Up-Regulation of CD163 Expression in Subpopulations of Blood Monocytes After Kidney Allograft Transplantation

M2 macrophages expressing CD163 are known to suppress immune responses but have been also found in biopsies of patients with chronic kidney allograft injury associated with interstitial fibrosis. The aim of our study was to evaluate the expression of CD163 in blood monocytes, precursors of tissue macrophages, in kidney allograft recipients with uncomplicated outcome (n=94) compared with those developing acute rejection (n=44). Blood samples were collected before the transplantation and at 1 week, 1 month and 1 year. The expression of CD163 increased during the first week after the transplantation not only in classical (CD14+CD16-) but also in intermediate (CD14+CD16+) and nonclassical (CD14lowCD16+) monocytes in all patients regardless of their rejection status. In patients developing acute rejection, higher pre-transplant expression of CD163 on blood monocytes was found. In vitro experiments confirmed strong induction of membrane CD163 on monocytes together with CD206 (an alternative marker of M2 macrophages) in response to IL-10. We assume from our data that dramatic upregulation of CD163 by peripheral blood monocytes may have a pathophysiological role in early phases after kidney allograft transplantation and high pre-transplant expression of CD163 on blood monocytes might be involved in events leading to acute rejection.

Renal hyperfiltration as a risk factor for chronic kidney disease: A health checkup cohort study

Introduction

Renal hyperfiltration (RHF) has been found to be an independent predictor of adverse cardiovascular outcome. However, it remains uncertain whether it is precursor of chronic kidney disease (CKD) in a healthy population.

Materials and methods

To determine relative risks and identify the predictor of incident proteinuria and decline of estimated glomerular filtration rate (eGFR) in subjects with RHF. A total of 55,992 subjects aged ≥20 years who underwent health check-up during 2004–2017 were included. Among them, 16,946 subjects who completed at least two health checkups were analyzed.

Results

A total of 949 (5.6%) subjects developed proteinuria and 98 (0.6%) subjects showed ≥ 30% of eGFR decline. The risk of incident proteinuria was significantly higher in those with RHF (RR: 1.644; 95% CI: 1.064–2.541). Those with RHF showed 8.720 fold (95% CI: 4.205–18.081) increased risk for ≥30% decline. ESR, CRP, and monocyte count showed reversed J shaped curve according to the increase of eGFR. The adjusted mean of monocyte count was significantly higher in participants with eGFR ≥90ml/min/1.73m² or < 60ml/min/1.73m² compared to that in patients with eGFR 75-89ml/min/1.73m². Compared to subjects with the lowest tertile of monocyte and no RHF, those with the highest tertile of monocyte count in the RHF group had 3.314-fold (95% CI: 1.893–5.802) higher risk of incident proteinuria and 3.822-fold (95% CI, 1.327–11.006) risk of 30% eGFR decline.

Conclusions

RHF had significantly increased risk of developing proteinuria and CKD in healthy subjects. Higher monocyte count might be used as a predictor of CKD in subjects with RHF.

Chitotriosidase as a Novel Biomarker for Therapeutic Monitoring of Nephropathic Cystinosis

BACKGROUND

Nephropathic cystinosis, a hereditary lysosomal storage disorder caused by dysfunction of the lysosomal cotransporter cystinosin, leads to cystine accumulation and cellular damage in various organs, particularly in the kidney. Close therapeutic monitoring of cysteamine, the only available disease-modifying treatment, is recommended. White blood cell cystine concentration is the current gold standard for therapeutic monitoring, but the assay is technically demanding and is available only on a limited basis. Because macrophage-mediated inflammation plays an important role in the pathogenesis of cystinosis, biomarkers of macrophage activation could have potential for the therapeutic monitoring of cystinosis.

METHODS

We conducted a 2-year prospective, longitudinal study in which 61 patients with cystinosis who were receiving cysteamine therapy were recruited from three European reference centers. Each regular care visit included measuring four biomarkers of macrophage activation: IL-1β, IL-6, IL-18, and chitotriosidase enzyme activity.

RESULTS

A multivariate linear regression analysis of the longitudinal data for 57 analyzable patients found chitotriosidase enzyme activity and IL-6 to be significant independent predictors for white blood cell cystine levels in patients of all ages with cystinosis; a receiver operating characteristic analysis ranked chitotriosidase as superior to IL-6 in distinguishing good from poor therapeutic control (on the basis of white blood cell cystine levels of <2 nmol 1/2 cystine/mg protein or ≥2 nmol 1/2 cystine/mg protein, respectively). Moreover, in patients with at least one extrarenal complication, chitotriosidase significantly correlated with the number of extrarenal complications and was superior to white blood cell cystine levels in predicting the presence of multiple extrarenal complications.

CONCLUSIONS

Chitotriosidase enzyme activity holds promise as a biomarker for use in therapeutic monitoring of nephropathic cystinosis.

The global and national burden of chronic kidney disease attributable to ambient fine particulate matter air pollution: a modelling study

Introduction

We aimed to integrate all available epidemiological evidence to characterise an exposure–response model of ambient fine particulate matter (PM_2.5) and the risk of chronic kidney disease (CKD) across the spectrum of PM_2.5 concentrations experienced by humans. We then estimated the global and national burden of CKD attributable to PM_2.5.

Methods

We collected data from prior studies on the association of PM_2.5 with CKD and used an integrative meta-regression approach to build non-linear exposure–response models of the risk of CKD associated with PM_2.5 exposure. We then estimated the 2017 global and national incidence, prevalence, disability-adjusted life-years (DALYs) and deaths due to CKD attributable to PM_2.5 in 194 countries and territories. Burden estimates were generated by linkage of risk estimates to Global Burden of Disease study datasets.

Results

The exposure–response function exhibited evidence of an increase in risk with increasing PM_2.5 concentrations, where the rate of risk increase gradually attenuated at higher PM_2.5 concentrations. Globally, in 2017, there were 3 284 358.2 (95% UI 2 800 710.5 to 3 747 046.1) incident and 122 409 460.2 (108 142 312.2 to 136 424 137.9) prevalent cases of CKD attributable to PM_2.5, and 6 593 134.6 (5 705 180.4 to 7 479 818.4) DALYs and 211 019.2 (184 292.5 to 236 520.4) deaths due to CKD attributable to PM_2.5. The burden was disproportionately borne by low income and lower middle income countries and exhibited substantial geographic variability, even among countries with similar levels of sociodemographic development. Globally, 72.8% of prevalent cases of CKD attributable to PM_2.5 and 74.2% of DALYs due to CKD attributable to PM_2.5 were due to concentrations above 10 µg/m³, the WHO air quality guidelines.

Conclusion

The global burden of CKD attributable to PM_2.5 is substantial, varies by geography and is disproportionally borne by disadvantaged countries. Most of the burden is associated with PM_2.5 levels above the WHO guidelines, suggesting that achieving those targets may yield reduction in CKD burden.

Diabetes Minimally Mediated the Association Between PM2.5 Air Pollution and Kidney Outcomes

Epidemiologic observations suggest that exposure to ambient fine particulate matter (PM_2.5) is associated with increased risk of chronic kidney disease (CKD) and diabetes, a causal driver of CKD. We evaluated whether diabetes mediates the association between PM_2.5 and CKD. A cohort of 2,444,157 United States veterans were followed over a median 8.5 years. Environmental Protection Agency data provided PM_2.5 exposure levels_. Regression models assessed associations and their proportion mediated. A 10 µg/m³ increase in PM_2.5 was associated with increased odds of having a diabetes diagnosis (odds ratio: 1.18, 95% CI: 1.06–1.32), use of diabetes medication (1.22, 1.07–1.39), and increased risk of incident eGFR <60 ml/min/1.73 m² (hazard ratio:1.20, 95% CI: 1.13–1.29), incident CKD (1.28, 1.18–1.39), ≥30% decline in eGFR (1.23, 1.15–1.33), and end-stage renal disease (ESRD) or ≥50% decline in eGFR (1.17, 1.05–1.30). Diabetes mediated 4.7% (4.3–5.7%) of the association of PM_2.5 with incident eGFR <60 ml/min/1.73 m², 4.8% (4.2–5.8%) with incident CKD, 5.8% (5.0–7.0%) with ≥30% decline in eGFR, and 17.0% (13.1–20.4%) with ESRD or ≥50% decline in eGFR. Diabetes minimally mediated the association between PM_2.5 and kidney outcomes. The findings will help inform more accurate estimates of the burden of diabetes and burden of kidney disease attributable to PM_2.5 pollution.

From Local Explanations to Global Understanding with Explainable AI for Trees

Tree-based machine learning models such as random forests, decision trees, and gradient boosted trees are popular non-linear predictive models, yet comparatively little attention has been paid to explaining their predictions. Here, we improve the interpretability of tree-based models through three main contributions: 1) The first polynomial time algorithm to compute optimal explanations based on game theory. 2) A new type of explanation that directly measures local feature interaction effects. 3) A new set of tools for understanding global model structure based on combining many local explanations of each prediction. We apply these tools to three medical machine learning problems and show how combining many high-quality local explanations allows us to represent global structure while retaining local faithfulness to the original model. These tools enable us to i) identify high magnitude but low frequency non-linear mortality risk factors in the US population, ii) highlight distinct population sub-groups with shared risk characteristics, iii) identify non-linear interaction effects among risk factors for chronic kidney disease, and iv) monitor a machine learning model deployed in a hospital by identifying which features are degrading the model's performance over time. Given the popularity of tree-based machine learning models, these improvements to their interpretability have implications across a broad set of domains.

Immunology of the ageing kidney

Immunosenescence involves a series of ageing-induced alterations in the immune system and is characterized by two opposing hallmarks: defective immune responses and increased systemic inflammation. The immune system is modulated by intrinsic and extrinsic factors and undergoes profound changes in response to the ageing process. Immune responses are therefore highly age-dependent. Emerging data show that immunosenescence underlies common mechanisms responsible for several age-related diseases and is a plastic state that can be modified and accelerated by non-heritable environmental factors and pharmacological intervention. In the kidney, resident macrophages and fibroblasts are continuously exposed to components of the external environment, and the effects of cellular reprogramming induced by local immune responses, which accumulate with age, might have a role in the increased susceptibility to kidney disease among elderly individuals. Additionally, because chronic kidney disease, especially end-stage renal disease, is often accompanied by immunosenescence, which affects these patients independently of age, and many kidney diseases are strongly age-associated, treatment approaches that target immunosenescence might be particularly clinically relevant.

Peripheral Monocyte Count Predicts Outcomes in Patients with Acute Ischemic Stroke Treated with rtPA Thrombolysis

The aim of this study was to investigate the predictive value of the monocyte count as a prognostic biomarker on 90 days in patients with acute ischemic stroke (AIS) treated with recombinant tissue plasminogen activator (rtPA) thrombolysis. In total, 206 patients with AIS treated in our institute between 2013 and 2018 were retrospectively enrolled. All patients received rtPA thrombolytic therapy within 4.5 h of AIS onset. Using receiver operating characteristic (ROC) curve analysis, patients were divided into two groups according to monocyte count: a low monocyte count (LMC) group (monocytes < 0.53 × 10⁹/L) and a high monocyte count (HMC) group (monocytes ≥ 0.53 × 10⁹/L). Patients' functional outcomes 90 days after AIS were assessed using the modified Rankin Scale. More patients had a poor outcome in the HMC group than in the LMC group (49.32% vs.31.58%, p = 0.012). Multivariate logistic regression analysis revealed that infarct volume (odds ratio = 1.03, 95% confidence interval 1.01-1.04, p < 0.001), systolic pressure at admission (odds ratio = 1.02, 95% confidence interval 1.00-1.04, p = 0.016), fasting blood glucose at admission (odds ratio = 1.41, 95% confidence interval 1.18-1.67, p < 0.001), and monocyte count ≥ 0.53 × 10⁹/L (odds ratio = 2.25, 95% confidence interval 1.09-4.62, p = 0.028) were independently associated with a poor outcome in AIS patients treated with rtPA thrombolysis. A peripheral monocyte count ≥ 0.53 × 10⁹/L is an independent prognostic marker on 90-days in patients with AIS treated with rtPA thrombolysis.

Estimates of all cause mortality and cause specific mortality associated with proton pump inhibitors among US veterans: cohort study

OBJECTIVE

To estimate all cause mortality and cause specific mortality among patients taking proton pump inhibitors (PPIs).

DESIGN

Longitudinal observational cohort study.

SETTING

US Department of Veterans Affairs.

PARTICIPANTS

New users of PPIs (n=157 625) or H2 blockers (n=56 842).

MAIN OUTCOME MEASURES

All cause mortality and cause specific mortality associated with taking PPIs (values reported as number of attributable deaths per 1000 patients taking PPIs).

RESULTS

There were 45.20 excess deaths (95% confidence interval 28.20 to 61.40) per 1000 patients taking PPIs. Circulatory system diseases (number of attributable deaths per 1000 patients taking PPIs 17.47, 95% confidence interval 5.47 to 28.80), neoplasms (12.94, 1.24 to 24.28), infectious and parasitic diseases (4.20, 1.57 to 7.02), and genitourinary system diseases (6.25, 3.22 to 9.24) were associated with taking PPIs. There was a graded relation between cumulative duration of PPI exposure and the risk of all cause mortality and death due to circulatory system diseases, neoplasms, and genitourinary system diseases. Analyses of subcauses of death suggested that taking PPIs was associated with an excess mortality due to cardiovascular disease (15.48, 5.02 to 25.19) and chronic kidney disease (4.19, 1.56 to 6.58). Among patients without documented indication for acid suppression drugs (n=116 377), taking PPIs was associated with an excess mortality due to cardiovascular disease (22.91, 11.89 to 33.57), chronic kidney disease (4.74, 1.53 to 8.05), and upper gastrointestinal cancer (3.12, 0.91 to 5.44). Formal interaction analyses suggested that the risk of death due to these subcauses was not modified by a history of cardiovascular disease, chronic kidney disease, or upper gastrointestinal cancer. Taking PPIs was not associated with an excess burden of transportation related mortality and death due to peptic ulcer disease (as negative outcome controls).

CONCLUSIONS

Taking PPIs is associated with a small excess of cause specific mortality including death due to cardiovascular disease, chronic kidney disease, and upper gastrointestinal cancer. The burden was also observed in patients without an indication for PPI use. Heightened vigilance in the use of PPI may be warranted.

Chronic Kidney Disease Severity Is Associated With Selective Expansion of a Distinctive Intermediate Monocyte Subpopulation

Chronic kidney disease (CKD) affects 11–13% of the world's population and greatly increases risk of atherosclerotic cardiovascular disease (ASCVD) and death. It is characterized by systemic inflammation and disturbances in the blood leukocytes that remain incompletely understood. In particular, abnormalities in the numbers and relative proportions of the three major monocyte subsets—classical, intermediate, and non-classical—are described in CKD and end-stage renal disease. In this study, we characterized absolute numbers of blood leukocyte subtypes in adults with renal function varying from normal to advanced CKD. The primary aim was to identify monocyte subpopulations that associated most closely with current estimated glomerular filtration rate (eGFR) and subsequent rate of eGFR decline. Leucocyte and monocyte populations were enumerated by multi-color flow cytometry of whole blood and peripheral blood mononuclear cell (PBMC) samples from adults with CKD stage 1–5 (n = 154) and healthy adults (n = 33). Multiple-linear regression analyses were performed to identify associations between numbers of leucocyte and monocyte populations and clinical characteristics including eGFR and rate of eGFR decline with adjustment for age and gender. In whole blood, total monocyte and neutrophil, but not lymphocyte, numbers were higher in adults with CKD 1-5 compared to no CKD and were significantly associated with current eGFR even following correction for age. In PBMC, classical and intermediate monocyte numbers were higher in CKD 1-5 but only intermediate monocyte numbers were significantly associated with current eGFR in an age-corrected analysis. When intermediate monocytes were further sub-divided into those with mid- and high-level expression of class II MHC (HLA-DR^mid and HLA-DR^hi intermediate monocytes) it was found that only DR^hi intermediate monocytes were increased in number in CKD 1-5 compared to no CKD and were significantly associated with eGFR independently of age among the total (No CKD + CKD 1-5) study cohort as well as those with established CKD (CKD 1-5 only). Furthermore, blood number of DR^hi intermediate monocytes alone proved to be significantly associated with subsequent rate of renal functional decline. Together, our data confirm neutrophil and monocyte subset dysregulation in CKD and identify a distinct subpopulation of intermediate monocytes that is associated with higher rate of loss of kidney function.

Kidney damage induced by sub-chronic fine particulate matter exposure

According to the WHO, about 3 million people die each year due to ambient air pollution. Most of the in vivo studies on the PM_2.5 effects have been done on respiratory and cardiovascular tissues. However, little is known about the effects on the tissues involved on xenobiotic removal, such as kidneys. In the present study we assess the harmful effects of sub-chronic exposure to PM_2.5 on the kidney, by investigating histologic and serum alterations in healthy and hypertensive rat models. Mean PM_2.5 concentrations during exposures were slightly above the daily WHO standard. Exposed animals showed fibrosis, mesangial expansion, decrease glomerular and tubular lumen volumes in kidneys, with an elevated BUN. Hypertensive animals also exhibited much more severe alterations than healthy animals. We conclude that PM_2.5 induces minimal or small-scale abnormalities that can be determinant for renal health preservation.

Blood urea nitrogen and risk of insulin use among people with diabetes

Laboratory evidence suggests that urea suppresses insulin secretion and sensitivity. Emerging epidemiologic evidence suggests that higher levels of urea are associated with increased risk of incident diabetes mellitus. However, whether elevated levels of blood urea nitrogen are associated with increased risk of insulin use among people with diabetes is unknown. We used the Department of Veterans Affairs databases to assemble a cohort of 197,994 incident users of non-insulin hypoglycaemic agents with an estimated glomerular filtration rate > 60 mL/min per 1.73 m² and followed them for a median of 4.93 years. Spline analyses suggested that the relationship between blood urea nitrogen and the risk of insulin use was neutral below blood urea nitrogen level of 25 mg/dL and increased exponentially with blood urea nitrogen levels above 25 mg/dL. In survival models, compared to those with blood urea nitrogen ⩽ 25 mg/dL, those with blood urea nitrogen > 25 mg/dL had an increased risk of insulin use (hazard ratio = 1.40; confidence interval = 1.30-1.50). The risk of insulin use was increased in models which accounted for haemoglobin A1c at time zero (hazard ratio = 1.39; confidence interval = 1.28-1.50) and as a time-varying variable (hazard ratio = 1.38; confidence interval = 1.28-1.50). Two-step residual estimation analyses showed that, independent of the impact of estimated glomerular filtration rate, every 10-mg/dL increase in blood urea nitrogen concentration was associated with increased risk of insulin use (hazard ratio = 1.16; confidence interval = 1.12-1.20). Our results suggest that, among people with diabetes, higher levels of blood urea nitrogen are associated with an increased risk of insulin use.

White blood cell fractions correlate with lesions of diabetic kidney disease and predict loss of kidney function in Type 2 diabetes

BACKGROUND

Inflammation linked to diabetic kidney disease (DKD) may affect white blood cell (WBC) counts and differentials. We examined the cross-sectional associations of total WBC count and WBC fractions with structural lesions of DKD in 108 Pima Indians with Type 2 diabetes who underwent research kidney biopsies. We also examined the longitudinal association of these WBC variables with renal function loss (RFL) in 941 Europeans with Type 2 diabetes from the SURDIAGENE study.

METHODS

Associations of WBC variables with morphometric parameters were assessed by linear regression. RFL was defined as≥40% loss of estimated glomerular filtration rate from baseline. Associations with RFL were evaluated by Cox regression. Hazard ratios (HRs) were reported per standard deviation increment of each WBC variable.

RESULTS

After multivariable adjustment, lymphocyte (r  = -0.20, P = 0.043) and eosinophil (r = 0.21, P = 0.032) fractions in the Pima Indians correlated with glomerular basement membrane width. Eosinophil fraction also correlated with glomerular filtration surface density (r  = -0.21, P = 0.031). Lymphocyte fraction (r = 0.25, P = 0.013), neutrophil fraction (r  = -0.23, P = 0.021) and the neutrophil:lymphocyte ratio (r  = -0.22, P = 0.024) correlated with percentage of normally fenestrated endothelial cells. During median follow-up of 4.5 years, 321 SURDIAGENE participants developed RFL. Lower lymphocyte fraction [HR = 0.67, 95% confidence interval (95% CI) 0.60-0.76] and higher neutrophil fraction (HR = 1.35, 95% CI 1.20-1.52), total WBC count (HR = 1.20, 95% CI 1.08-1.35) and neutrophil:lymphocyte ratio (HR = 1.44, 95% CI 1.28-1.62) each predicted RFL in this cohort.

CONCLUSIONS

WBC fractions associate with morphometric lesions of DKD and predict RFL in individuals with Type 2 diabetes.

The human circulating miRNome reflects multiple organ disease risks in association with short-term exposure to traffic-related air pollution

Traffic-related air pollution is a complex mixture of particulate matter (PM) and gaseous pollutants, such as nitrogen dioxide (NO2). PM exposure contributes to the pathogenesis of many diseases including several types of cancer, as well as pulmonary, cardiovascular and neurodegenerative diseases. Also exposure to NO2 has been related to increased cardiovascular mortality. In search of an early diagnostic biomarker for improved air pollution-associated health risk assessment, recent human studies have shown that certain circulating miRNAs are altered upon exposure to traffic-related air pollutants. Here, we present for the first time a global analysis of the circulating miRNA genome in an experimental cross-over study of a human population exposed to traffic-related air pollution. By utilizing next-generation sequencing technology and detailed real-time exposure measurements we identified 54 circulating miRNAs to be dose- and pollutant species-dependently associated with PM10, PM2.5, black carbon, ultrafine particles and NO2 already after 2 h of exposure. Bioinformatics analysis suggests that these circulating miRNAs actually reflect the adverse consequences of traffic pollution-induced toxicity in target tissues including the lung, heart, kidney and brain. This study shows the strong potential of circulating miRNAs as novel biomarkers for environmental health risk assessment.

Traffic-related air pollution associated with chronic kidney disease among elderly residents in Taipei City

The associations of air pollution with chronic kidney disease (CKD) have not yet been fully studied. We enrolled 8,497 Taipei City residents older than 65 years and calculated the estimated glomerular filtration rate (eGFR) using the Taiwanese Chronic Kidney Disease Epidemiology Collaboration equation. Proteinuria was assessed via dipstick on voided urine. CKD prevalence and risk of progression were defined according to the KDIGO 2012 guidelines. Land-use regression models were used to estimate the participants' one-year exposures to PM of different sizes and traffic-related exhaust, PM_2.5 absorbance, nitrogen dioxide (NO₂), and NO_x. Generalized linear regressions and logistic regressions were used to examine the associations of one-year air pollution exposures with eGFR, proteinuria, CKD prevalence and risk of progression. The results showed that the interquartile range (IQR) increments of PM_2.5 absorbance (0.4 × 10^-5/m) and NO₂ (7.0 μg/m³) were associated with a 1.07% [95% confidence interval (CI): 0.54-1.57] and 0.84% (95% CI: 0.37-1.32) lower eGFR, respectively; such relationships were magnified in subjects who had an eGFR >60 ml/min/1.73 m² or who were non-diabetic. Similar associations were also observed for PM₁₀ and PM_2.5-10. Two-pollutant models showed that PM₁₀ and PM_2.5 absorbance were associated with a lower eGFR. The odd ratios (ORs) of CKD prevalence and risk of progression also increased with exposures to PM_2.5 absorbance and NO_2. In summary, one-year exposures to traffic-related air pollution were associated with lower eGFR, higher CKD prevalence, and increased risk of CKD progression among the elderly population. Air pollution-related impaired renal function was stronger in non-CKD and non-diabetic subjects.

Higher blood urea nitrogen is associated with increased risk of incident diabetes mellitus

Experimental evidence suggests that higher levels of urea may increase insulin resistance and suppress insulin secretion. However, whether higher levels of blood urea nitrogen (BUN) are associated with increased risk of incident diabetes mellitus in humans is not known. To study this, we built a national cohort of 1,337,452 United States Veterans without diabetes to characterize the association of BUN and risk of incident diabetes. Over a median follow-up of 4.93 years, there were 172,913 cases of incident diabetes. In joint risk models of estimated glomerular filtration rate (eGFR) and BUN. there was no association between eGFR and the risk of incident diabetes in those with a BUN of 25 mg/dl or less. However, the risk was significantly increased in those with a BUN over 25 mg/dl at all eGFR levels, even in those with an eGFR of 60 ml/min/1.73m² or more (hazard ratio 1.27; confidence interval 1.24-1.31). The risk of incident diabetes was highest in those with BUN over 25 mg/dL and an eGFR under 15 ml/min/1.73m² (1.68; 1.51-1.87). Spline analyses of the relationship between BUN and risk of incident diabetes showed that risk was progressively higher as BUN increased. In models where eGFR was included as a continuous covariate, compared to a BUN of 25 mg/dl or less, a BUN over 25 mg/dl was associated with increased risk of incident diabetes (1.23; 1.21-1.25). Every 10 ml/min/1.73m² decrease in eGFR was not associated with risk of incident diabetes (1.00; 1.00-1.01). Two-stage residual inclusion analyses showed that, independent of the impact of eGFR, every 10 mg/dL increase in BUN concentration was associated with increased risk of incident diabetes (1.15; 1.14-1.16). Thus, higher levels of BUN are associated with increased risk of incident diabetes mellitus.

Associations of ambient coarse particulate matter, nitrogen dioxide, and carbon monoxide with the risk of kidney disease: a cohort study

BACKGROUND

Experimental evidence and preliminary clinical evidence suggest that environmental air pollution adversely effects kidney health. Previous work has examined the association between fine particulate matter and risk of kidney disease; however, the association between ambient coarse particulate matter (PM₁₀; ≤10 μm in aerodynamic diameter), nitrogen dioxide (NO₂), and carbon monoxide (CO) and risk of incident chronic kidney disease, chronic kidney disease progression, and end-stage renal disease is not clear.

METHODS

We merged multiple large databases, including those of the Environmental Protection Agency and the Department of Veterans Affairs, to build a cohort of US veterans, and used survival models to evaluate the association between PM₁₀, NO₂, and CO concentrations and risk of incident estimated glomerular filtration rate (eGFR) of less than 60 mL/min per 1·73 m², incident chronic kidney disease, eGFR decline of 30% or more, and end-stage renal disease. We treated exposure as time-varying when it was updated annually and as cohort participants moved.

FINDINGS

Between Oct 1, 2003, and Sept 30, 2012, 2 010 398 cohort participants were followed up over a median of 8·52 years (IQR 8·05-8·80). An increased risk of eGFR of less than 60 mL/min per 1·73 m² was associated with an IQR increase in concentrations of PM₁₀ (hazard ratio 1·07, 95% CI 1·06-1·08), NO₂ (1·09, 1·08-1·10), and CO (1·09, 1·08-1·10). An increased risk of incident chronic kidney disease was associated with an IQR increase in concentrations of PM₁₀ (1·07, 1·05-1·08), NO₂ (1·09, 1·08-1·11), and CO (1·10, 1·08-1·11). An increased risk of an eGFR decline of 30% or more was associated with an IQR increase in concentrations of PM₁₀ (1·08, 1·07-1·09), NO₂ (1·12, 1·10-1·13), and CO (1·09, 1·08-1·10). An increased risk of end-stage renal disease was associated with an IQR increase in concentrations of PM₁₀ (1·09, 1·06-1·12), NO₂ (1·09, 1·06-1·12), and CO (1·05, 1·02-1·08). Spline analyses suggested a monotonic increasing association between PM₁₀, NO₂, and CO concentrations and risk of kidney outcomes.

INTERPRETATION

Environmental exposure to higher concentrations of PM₁₀, NO₂, and CO is associated with increased risk of incident chronic kidney disease, eGFR decline, and end-stage renal disease.

FUNDING

US Department of Veterans Affairs.