Differential effects of biocompatible peritoneal dialysis fluids on human mesothelial and endothelial cells in 2D and 3D phenotypes

INTRODUCTION

Peritoneal dialysis (PD) is a life maintaining treatment in patients with end-stage renal disease. Its chronic application leads to peritoneal mesothelial layer denudation and fibrotic transformation along with vascular activation of inflammatory pathways. The impact of different PD fluids (PDF) on mesothelial and endothelial cell function and repair mechanisms are not comprehensively described.

MATERIALS AND METHODS

Mesothelial (MeT-5A) and endothelial cells (EA.hy926) were cultured in 1:1 ratio with cell medium and different PDF (icodextrin-based, amino acid-based, and glucose-based). Cell adhesion, cell migration, and cell proliferation in 2D and spheroid formation and collagen gel contraction assays in 3D cell cultures were performed.

RESULTS

Cell proliferation and cell-mediated gel contraction were both significantly decreased in all conditions. 3D spheroid formation was significantly reduced with icodextrin and amino acid PDF, but unchanged with glucose PDF. Adhesion was significantly increased by amino acid PDF in mesothelial cells and decreased by icodextrin and amino acid PDF in endothelial cells. Migration capacity was significantly decreased in mesothelial cells by all three PDF, while endothelial cells remained unaffected.

CONCLUSIONS

In 3D phenotypes the effects of PDF are more uniform in both mesothelial and endothelial cells, mitigating spheroid formation and gel contraction. On the contrary, effects on 2D phenotypes are more uniform in the icodextrin and amino acid PDF as opposed to glucose ones and affect mesothelial cells more variably. 2D and 3D comparative assessments of PDF effects on the main peritoneal membrane cell barriers, the mesothelial and endothelial, could provide useful translational information for PD studies.

Clinical practice recommendations on lipoprotein apheresis for children with homozygous familial hypercholesterolaemia: An expert consensus statement from ERKNet and ESPN

Homozygous familial hypercholesterolaemia is a life-threatening genetic condition, which causes extremely elevated LDL-C levels and atherosclerotic cardiovascular disease very early in life. It is vital to start effective lipid-lowering treatment from diagnosis onwards. Even with dietary and current multimodal pharmaceutical lipid-lowering therapies, LDL-C treatment goals cannot be achieved in many children. Lipoprotein apheresis is an extracorporeal lipid-lowering treatment, which is used for decades, lowering serum LDL-C levels by more than 70% directly after the treatment. Data on the use of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia mainly consists of case-reports and case-series, precluding strong evidence-based guidelines. We present a consensus statement on lipoprotein apheresis in children based on the current available evidence and opinions from experts in lipoprotein apheresis from over the world. It comprises practical statements regarding the indication, methods, treatment goals and follow-up of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia and on the role of lipoprotein(a) and liver transplantation.

Real-world evidence on the dosing and safety of C.E.R.A. in pediatric dialysis patients: findings from the International Pediatric Dialysis Network registries

BACKGROUND

This retrospective real-world study used data from two registries, International Pediatric Peritoneal Dialysis Network (IPPN) and International Pediatric Hemodialysis Network (IPHN), to characterize the efficacy and safety of continuous erythropoietin receptor activator (C.E.R.A.) in pediatric patients with chronic kidney disease (CKD) on peritoneal dialysis (PD) or hemodialysis (HD).

METHODS

IPPN and IPHN collect prospective data (baseline and every 6 months) from pediatric PD and HD centers worldwide. Demographics, clinical characteristics, dialysis information, treatment, laboratory parameters, number and causes of hospitalization events, and deaths were extracted for patients on C.E.R.A. treatment (IPPN: 2007-2021; IPHN: 2013-2021).

RESULTS

We analyzed 177 patients on PD (median age 10.6 years) and 52 patients on HD (median age 14.1 years) who had ≥ 1 observation while being treated with C.E.R.A. The median (interquartile range [IQR]) observation time under C.E.R.A. exposure was 6 (0-12.5) and 12 (0-18) months, respectively. Hemoglobin concentrations were stable over time; respective means (standard deviation) at last observation were 10.9 (1.7) g/dL and 10.4 (1.7) g/dL. Respective median (IQR) monthly C.E.R.A. doses at last observation were 3.5 (2.3-5.1) µg/kg, or 95 (62-145) µg/m2 and 2.1 (1.2-3.4) µg/kg, or 63 (40-98) µg/m2. Non-elective hospitalizations occurred in 102 (58%) PD and 32 (62%) HD patients. Seven deaths occurred (19.8 deaths per 1000 observation years).

CONCLUSIONS

C.E.R.A. was associated with efficient maintenance of hemoglobin concentrations in pediatric patients with CKD on dialysis, and appeared to have a favorable safety profile. The current analysis revealed no safety signals.

2-Deoxy-glucose ameliorates the peritoneal mesothelial and endothelial barrier function perturbation occurring due to Peritoneal Dialysis fluids exposure

Peritoneal dialysis (PD) and prolonged exposure to PD fluids (PDF) induce peritoneal membrane (PM) fibrosis and hypervascularity, leading to functional PM degeneration. 2-deoxy-glucose (2-DG) has shown potential as PM antifibrotic by inhibiting hyper-glycolysis induced mesothelial-to-mesenchymal transition (MMT). We investigated whether administration of 2-DG with several PDF affects the permeability of mesothelial and endothelial barrier of the PM. The antifibrotic effect of 2-DG was confirmed by the gel contraction assay with embedded mesothelial (MeT-5A) or endothelial (EA.hy926) cells cultured in Dianeal® 2.5 % (CPDF), BicaVera® 2.3 % (BPDF), Balance® 2.3 % (LPDF) with/without 2-DG addition (0.2 mM), and qPCR for αSMA, CDH2 genes. Moreover, 2-DG effect was tested on the permeability of monolayers of mesothelial and endothelial cells by monitoring the transmembrane resistance (RTM), FITC-dextran (10, 70 kDa) diffusion and mRNA expression levels of CLDN-1 to -5, ZO1, SGLT1, and SGLT2 genes. Contractility of MeT-5A cells in CPDF/2-DG was decreased, accompanied by αSMA (0.17 ± 0.03) and CDH2 (2.92 ± 0.29) gene expression fold changes. Changes in αSMA, CDH2 were found in EA.hy926 cells, though αSMA also decreased under LPDF/2-DG incubation (0.42 ± 0.02). Overall, 2-DG mitigated the PDF-induced alterations in mesothelial and endothelial barrier function as shown by RTM, dextran transport and expression levels of the CLDN-1 to -5, ZO1, and SGLT2. Thus, supplementation of PDF with 2-DG not only reduces MMT but also improves functional permeability characteristics of the PM mesothelial and endothelial barrier.

Comparative analysis of hospitalizations among patients treated with hemodialysis and peritoneal dialysis in European pediatric nephrology centers: results from a prospective EPDWG/ESPN Dialysis Working Group study

Background and hypothesis

Hospital admissions in pediatric dialysis patients need to be better studied, and most existing studies are retrospective and based on registry data. This study aimed to analyse and compare hospital admission rates, causes, length of stay (LOS), and outcomes in children treated with peritoneal dialysis (PD) and hemodialysis (HD).

Methods

Data from 236 maintenance PD and 138 HD patients across 16 European dialysis centers were collected between 1 July 2017 and 30 June 2018. A total of 178 hospitalized patients (103 PD, 75 HD) were included for further analyses.

Results

There were 465 hospitalization events (268 PD, 197 HD) with a rate of 0.39 admissions per 100 patient-days at risk (PDAR) and 2.4 hospital days per 100 PDAR. The admission rates were not significantly different between HD and PD patients. The most common causes of hospitalization were access-related infections (ARI) (17%), non-infectious complications of access (NIAC) (14%), and infections unrelated to access (12%). ARI was the leading cause in PD patients (24%), while NIAC was more common in HD patients (19%). PD patients had more ARIs, diagnostic procedures, and treatment adjustments (P < .05), while HD patients had more NIACs, infections unrelated to access, access placement procedures, and interventional/surgical procedures (P < .001). LOS was longer with acute admissions than non-acute admissions (P < .001). Overall LOS and LOS in the intensive care unit were similar between HD and PD patients. High serum uric acid and low albumin levels were significant predictors of longer LOS (P = .022 and P = .045, respectively). Young age, more significant height deficit, and older age at the start of dialysis were predictors of longer cumulative hospital days (P = .002, P = .001, and P = .031, respectively).

Conclusion

Access-related complications are the main drivers of hospitalization in pediatric dialysis patients, and growth and nutrition parameters are significant predictors of more extended hospital stays.

Technical requirements and devices available for long-term hemodialysis in children-mind the gap!

Children requiring long-term kidney replacement therapy are a "rare disease" cohort. While the basic technical requirements for hemodialysis (HD) are similar in children and adults, key aspects of the child's cardiovascular anatomy and hemodynamic specifications must be considered. In this article, we describe the technical requirements for long-term HD therapy for children and the devices that are currently available around the world. We highlight the characteristics and major technical shortcomings of permanent central venous catheters, dialyzers, dialysis machines, and software available to clinicians who care for children. We show that currently available HD machines are not equipped with appropriately small circuits and sensitive control mechanisms to perform safe and effective HD in the youngest patients. Manufacturers limit their liability, and health regulatory agencies permit the use of devices, only in children according to the manufacturers' pre-specified weight limitations. Although registries show that 6-23% of children starting long-term HD weigh less than 15 kg, currently, there is only one long-term HD device that is cleared for use in children weighing 10 to 15 kg and none is available and labelled for use in children weighing less than 10 kg anywhere in the world. Thus, many children are being treated "off-label" and are subject to interventions delivered by medical devices that lack pediatric safety and efficacy data. Moreover, recent improvements in dialysis technology offered to adult patients are denied to most children. We, in turn, advocate for concerted action by pediatric nephrologists, industry, and health regulatory agencies to increase the development of dedicated HD machines and equipment for children.

Sodium handling in pediatric patients on maintenance dialysis

The risk of cardiovascular disease remains exceedingly high in pediatric patients with chronic kidney disease stage 5 on dialysis (CKD 5D). Sodium (Na+) overload is a major cardiovascular risk factor in this population, both through volume-dependent and volume-independent toxicity. Given that compliance with a Na+-restricted diet is generally limited and urinary Na+ excretion impaired in CKD 5D, dialytic Na+ removal is critical to reduce Na+ overload. On the other hand, an excessive or too fast intradialytic Na+ removal may lead to volume depletion, hypotension, and organ hypoperfusion. This review presents current knowledge on intradialytic Na+ handling and possible strategies to optimize dialytic Na+ removal in pediatric patients on hemodialysis (HD) and peritoneal dialysis (PD). There is increasing evidence supporting the prescription of lower dialysate Na+ in salt-overloaded children on HD, while improved Na+ removal may be achieved in children on PD with an individual adaptation of dwell time and volume and with icodextrin use during the long dwell.

Clinical practice recommendations on lipoprotein apheresis for children with homozygous familial hypercholesterolemia: an expert consensus statement from ERKNet and ESPN

Homozygous familial hypercholesterolaemia is a life-threatening genetic condition, which causes extremely elevated LDL-C levels and atherosclerotic cardiovascular disease very early in life. It is vital to start effective lipid-lowering treatment from diagnosis onwards. Even with dietary and current multimodal pharmaceutical lipid-lowering therapies, LDL-C treatment goals cannot be achieved in many children. Lipoprotein apheresis is an extracorporeal lipid-lowering treatment, which is well established since three decades, lowering serum LDL-C levels by more than 70% per session. Data on the use of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia mainly consists of case-reports and case-series, precluding strong evidence-based guidelines. We present a consensus statement on lipoprotein apheresis in children based on the current available evidence and opinions from experts in lipoprotein apheresis from over the world. It comprises practical statements regarding the indication, methods, treatment targets and follow-up of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia and on the role of lipoprotein(a) and liver transplantation.

Calcimimetic AMG-416 induced short-term changes in calcium concentrations and calcium isotope ratios in rats

Calcium (Ca) isotopes (δ44/42Ca) in serum and urine have been suggested as novel sensitive markers of bone calcification. The response of δ44/42Ca to acute changes in Ca homeostasis, has not yet been demonstrated. We measured serum Ca and δ44/42Ca in rats maintained on a standard and a 50% Ca reduced diet for 4 weeks, and after injection of 1 mg/kg of the calcimimetic AMG-416, 24 h prior to sacrifice. AMG-416 decreased serum Ca by a maximum of 0.38 ± 0.10 and 0.53 ± 0.35 mmol/l after 12 and 6 h, respectively, in the standard and low-Ca diet groups (p = 0.0006/0.02), while serum δ44/42Ca did not change over 24 h in both groups. Urinary Ca concentrations were higher 24 h after AMG-416 injection in both groups (p = 0.03/0.06), urine δ44/42Ca was not different compared to the untreated control groups. Our data does not show acute changes in δ44/42Ca in response to a single dose of AMG-416 within 24 h after injection, possibly due to a lack of bone calcification.

Human peritoneal tight junction, transporter and channel expression in health and kidney failure, and associated solute transport

Next to the skin, the peritoneum is the largest human organ, essentially involved in abdominal health and disease states, but information on peritoneal paracellular tight junctions and transcellular channels and transporters relative to peritoneal transmembrane transport is scant. We studied their peritoneal localization and quantity by immunohistochemistry and confocal microscopy in health, in chronic kidney disease (CKD) and on peritoneal dialysis (PD), with the latter allowing for functional characterizations, in a total of 93 individuals (0-75 years). Claudin-1 to -5, and -15, zonula occludens-1, occludin and tricellulin, SGLT1, PiT1/SLC20A1 and ENaC were consistently detected in mesothelial and arteriolar endothelial cells, with age dependent differences for mesothelial claudin-1 and arteriolar claudin-2/3. In CKD mesothelial claudin-1 and arteriolar claudin-2 and -3 were more abundant. Peritonea from PD patients exhibited increased mesothelial and arteriolar claudin-1 and mesothelial claudin-2 abundance and reduced mesothelial and arteriolar claudin-3 and arteriolar ENaC. Transperitoneal creatinine and glucose transport correlated with pore forming arteriolar claudin-2 and mesothelial claudin-4/-15, and creatinine transport with mesothelial sodium/phosphate cotransporter PiT1/SLC20A1. In multivariable analysis, claudin-2 independently predicted the peritoneal transport rates. In conclusion, tight junction, transcellular transporter and channel proteins are consistently expressed in peritoneal mesothelial and endothelial cells with minor variations across age groups, specific modifications by CKD and PD and distinct associations with transperitoneal creatinine and glucose transport rates. The latter deserve experimental studies to demonstrate mechanistic links.Clinical Trial registration: The study was performed according to the Declaration of Helsinki and is registered at www.clinicaltrials.gov (NCT01893710).

Therapeutic targeting of chronic kidney disease-associated DAMPs differentially contributing to vascular pathology

Chronic Kidney Disease (CKD) is associated with markedly increased cardiovascular (CV) morbidity and mortality. Chronic inflammation, a hallmark of both CKD and CV diseases (CVD), is believed to drive this association. Pro-inflammatory endogenous TLR agonists, Damage-Associated Molecular Patterns (DAMPs), have been found elevated in CKD patients' plasma and suggested to promote CVD, however, confirmation of their involvement, the underlying mechanism(s), the extent to which individual DAMPs contribute to vascular pathology in CKD and the evaluation of potential therapeutic strategies, have remained largely undescribed. A multi-TLR inhibitor, soluble TLR2, abrogated chronic vascular inflammatory responses and the increased aortic atherosclerosis-associated gene expression observed in nephropathic mice, without compromising infection clearance. Mechanistically, we confirmed elevation of 4 TLR DAMPs in CKD patients' plasma, namely Hsp70, Hyaluronic acid, HMGB-1 and Calprotectin, which displayed different abilities to promote key cellular responses associated with vascular inflammation and progression of atherosclerosis in a TLR-dependent manner. These included loss of trans-endothelial resistance, enhanced monocyte migration, increased cytokine production, and foam cell formation by macrophages, the latter via cholesterol efflux inhibition. Calprotectin and Hsp70 most consistently affected these functions. Calprotectin was further elevated in CVD-diagnosed CKD patients and strongly correlated with the predictor of CV events CRP. In nephropathic mice, Calprotectin blockade robustly reduced vascular chronic inflammatory responses and pro-atherosclerotic gene expression in the blood and aorta. Taken together, these findings demonstrated the critical extent to which the DAMP-TLR pathway contributes to vascular inflammatory and atherogenic responses in CKD, revealed the mechanistic contribution of specific DAMPs and described two alternatives therapeutic approaches to reduce chronic vascular inflammation and lower CV pathology in CKD.

Sodium intake and urinary losses in children on dialysis: a European multicenter prospective study

BACKGROUND

Sodium (Na) balance is unexplored in dialyzed children. We assessed a simplified sodium balance (sNaB) and its correlates in pediatric patients receiving maintenance dialysis.

METHODS

Patients < 18 years old on hemodialysis (HD) or peritoneal dialysis (PD) in six European Pediatric Dialysis Working Group centers were recruited. sNaB was calculated from enteral Na, obtained by a 3-day diet diary, Na intake from medications, and 24-h urinary Na (uNa). Primary outcomes were systolic blood pressure and diastolic blood pressure standard deviation scores (SBP and DBP SDS), obtained by 24-h ambulatory blood pressure monitoring or office BP according to age, and interdialytic weight gain (IDWG).

RESULTS

Forty-one patients (31 HD), with a median age of 13.3 (IQR 5.2) years, were enrolled. Twelve patients (29.3%) received Na-containing drugs, accounting for 0.6 (0.7) mEq/kg/day. Median total Na intake was 1.5 (1.1) mEq/kg/day, corresponding to 60.6% of the maximum recommended daily intake for healthy children. Median uNa and sNaB were 0.6 (1.8) mEq/kg/day and 0.9 (1.7) mEq/kg/day, respectively. The strongest independent predictor of sNaB in the cohort was urine output. In patients receiving HD, sNaB correlated with IDWG, pre-HD DBP, and first-hour refill index, a volume index based on blood volume monitoring. sNaB was the strongest predictor of IDWG in multiple regression analysis (β = 0.63; p = 0.005). Neither SBP SDS nor DBP SDS correlated with sNaB.

CONCLUSIONS

Na intake is higher than uNa in children on dialysis, and medications may be an important source of Na. sNaB is best predicted by urine output in the population, and it is a significant independent predictor of IDWG in children on HD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Peritoneal transformation shortly after kidney transplantation in pediatric patients with preceding chronic peritoneal dialysis

BACKGROUND

The unphysiological composition of peritoneal dialysis (PD) fluids induces progressive peritoneal fibrosis, hypervascularization and vasculopathy. Information on these alterations after kidney transplantation (KTx) is scant.

METHODS

Parietal peritoneal tissues were obtained from 81 pediatric patients with chronic kidney disease stage 5 (CKD5), 72 children on PD with low glucose degradation product (GDP) PD fluids, and from 20 children 4-8 weeks after KTx and preceding low-GDP PD. Tissues were analyzed by digital histomorphometry and quantitative immunohistochemistry.

RESULTS

While chronic PD was associated with peritoneal hypervascularization, after KTx vascularization was comparable to CKD5 level. Submesothelial CD45 counts were 40% lower compared with PD, and in multivariable analyses independently associated with microvessel density. In contrast, peritoneal mesothelial denudation, submesothelial thickness and fibrin abundance, number of activated, submesothelial fibroblasts and of mesothelial-mesenchymal transitioned cells were similar after KTx. Diffuse peritoneal podoplanin positivity was present in 40% of the transplanted patients. In subgroups matched for age, PD vintage, dialytic glucose exposure and peritonitis incidence, submesothelial hypoxia-inducible factor 1-alpha abundance and angiopoietin 1/2 ratio were lower after KTx, reflecting vessel maturation, while arteriolar and microvessel p16 and cleaved Casp3 were higher. Submesothelial mast cell count and interleukin-6 were lower, whereas transforming growth factor-beta induced pSMAD2/3 was similar as compared with children on PD.

CONCLUSIONS

Peritoneal membrane damage induced with chronic administration of low-GDP PD fluids was less severe after KTx. While peritoneal microvessel density, primarily defining PD transport and ultrafiltration capacity, was normal after KTx and peritoneal inflammation less pronounced, diffuse podoplanin positivity and profibrotic activity were prevalent.

Diagnosis and management of mineral and bone disorders in infants with CKD: clinical practice points from the ESPN CKD-MBD and Dialysis working groups and the Pediatric Renal Nutrition Taskforce

BACKGROUND

Infants with chronic kidney disease (CKD) form a vulnerable population who are highly prone to mineral and bone disorders (MBD) including biochemical abnormalities, growth retardation, bone deformities, and fractures. We present a position paper on the diagnosis and management of CKD-MBD in infants based on available evidence and the opinion of experts from the European Society for Paediatric Nephrology (ESPN) CKD-MBD and Dialysis working groups and the Pediatric Renal Nutrition Taskforce.

METHODS

PICO (Patient, Intervention, Comparator, Outcomes) questions were generated, and relevant literature searches performed covering a population of infants below 2 years of age with CKD stages 2-5 or on dialysis. Clinical practice points (CPPs) were developed and leveled using the American Academy of Pediatrics grading matrix. A Delphi consensus approach was followed.

RESULTS

We present 34 CPPs for diagnosis and management of CKD-MBD in infants, including dietary control of calcium and phosphate, and medications to prevent and treat CKD-MBD (native and active vitamin D, calcium supplementation, phosphate binders).

CONCLUSION

As there are few high-quality studies in this field, the strength of most statements is weak to moderate, and may need to be adapted to individual patient needs by the treating physician. Research recommendations to study key outcome measures in this unique population are suggested. A higher resolution version of the Graphical abstract is available as Supplementary information.

Carnosinase-1 Knock-Out Reduces Kidney Fibrosis in Type-1 Diabetic Mice on High Fat Diet

Carnosine and anserine supplementation markedLy reduce diabetic nephropathy in rodents. The mode of nephroprotective action of both dipeptides in diabetes, via local protection or improved systemic glucose homeostasis, is uncertain. Global carnosinase-1 knockout mice (Cndp1-KO) and wild-type littermates (WT) on a normal diet (ND) and high fat diet (HFD) (n = 10/group), with streptozocin (STZ)-induced type-1 diabetes (n = 21-23/group), were studied for 32 weeks. Independent of diet, Cndp1-KO mice had 2- to 10-fold higher kidney anserine and carnosine concentrations than WT mice, but otherwise a similar kidney metabolome; heart, liver, muscle and serum anserine and carnosine concentrations were not different. Diabetic Cndp1-KO mice did not differ from diabetic WT mice in energy intake, body weight gain, blood glucose, HbA1c, insulin and glucose tolerance with both diets, whereas the diabetes-related increase in kidney advanced glycation end-product and 4-hydroxynonenal concentrations was prevented in the KO mice. Tubular protein accumulation was lower in diabetic ND and HFD Cndp1-KO mice, interstitial inflammation and fibrosis were lower in diabetic HFD Cndp1-KO mice compared to diabetic WT mice. Fatalities occurred later in diabetic ND Cndp1-KO mice versus WT littermates. Independent of systemic glucose homeostasis, increased kidney anserine and carnosine concentrations reduce local glycation and oxidative stress in type-1 diabetic mice, and mitigate interstitial nephropathy in type-1 diabetic mice on HFD.

Impact of Cinacalcet and Etelcalcetide on Bone Mineral and Cardiovascular Disease in Dialysis Patients

PURPOSES OF REVIEW

With chronic kidney disease (CKD) progression, secondary hyperparathyroidism (sHPT) and mineral and bone metabolism disease (MBD) almost inevitably develop and result in renal osteodystrophy and cardiovascular disease (CVD). Together with active vitamin D, calcimimetics are the main therapy for sHPT in CKD. This review provides an overview of the therapeutic effects of oral cinacalcet and intravenous etelcalcetide on CKD-MBD and vascular disease, with a focus on pediatric dialysis patients.

RECENT FINDINGS

Randomized controlled trials in adults and children demonstrate efficient lowering of parathyroid hormone (PTH) by the calcimimetics together with a reduction in serum calcium and phosphate when combined with low-dose active vitamin D, while therapy with active vitamin D analogs alone increases serum calcium and phosphate. Cinacalcet and etelcalcetide both improve bone formation and correct adynamic bone, i.e., have a direct bone anabolic effect. They decrease serum calciprotein particles, which are involved in endothelial dysfunction, atherogenesis, and vascular calcification. Clinical trials in adults suggest a modest slowing of the progression of cardiovascular calcification with cinacalcet. Calcimimetic agents represent a major pharmacological tool for improved control of CKD-MBD, by efficiently counteracting sHPT and allowing for better control of calcium/phosphate and bone homeostasis. Albeit definite evidence is lacking, the beneficial effects of calcimimetics on CVD are promising. Routine use of cinacalcet has been suggested in children.

Missing trial results: analysis of the current publication rate of studies in pediatric dialysis from 2003 to 2020

BACKGROUND

Decision-making in the field of pediatric dialysis requires evidence from clinical trials, but, similar to other fields of pediatric medicine, might be affected by a low trial publication rate.

METHODS

We analyzed the current publication rate, the time to publication, and factors that might be associated with both rate of and time to publication in pediatric dialysis studies registered as completed on ClinicalTrials.gov from 2003 until November 2020.

RESULTS

Fifty-three respective studies were identified. These enrolled 7287 patients in total. 28 of 53 studies (52.8%) had results available. We identified a median time to publication of 20.5 months (range, 3-67). Studies published after the FDA Amendments Act establishment in 2007 were published faster (P = 0.025). There was no trend toward a higher publication rate of studies completed more recently (P = 0.431). 26 of 53 studies (49.1%) focused on medication and control of secondary complications of kidney failure. 12 of 53 studies (22.6%) enrolled only children, were published faster (P = 0.029) and had a higher 5-year publication rate (P = 0.038) than studies enrolling both children and adults. 25 of 53 studies (47.1%) were co-funded by industry. These were published faster (P = 0.025).

CONCLUSIONS

Currently, only 52.8% of all investigated studies in pediatric dialysis have available results, and the overall median time to publication did not meet FDA requirements. This might introduce a publication bias into the field, and it might negatively impact clinical decision-making in this critical subspecialty of pediatric medicine. A higher resolution version of the Graphical abstract is available as Supplementary information.

Nutritional and Anthropometric Indices in Children Receiving Haemodiafiltration vs Conventional Haemodialysis - The HDF, Heart and Height (3H) Study

BACKGROUND

The "HDF-Heart-Height" study showed that haemodiafiltration (HDF) is associated with improved growth compared to conventional haemodialysis (HD). We report a post-hoc analysis of this study assessing the effect of extracorporeal dialysis therapies on nutritional indices.

METHODS

107 children were included in the baseline cross-sectional analysis, of whom 79 (43 HD, 36 HDF) completed the 12-month follow-up. Height (Ht), optimal 'dry' weight (Wt), and body mass index (BMI) standard deviations scores (SDS), waist-to-hip ratio, des-acyl ghrelin (DAG), adiponectin, leptin, insulin-like growth factor-1 (IGF-1)-SDS and insulin were measured.

RESULTS

The levels of nutritional indices were comparable between HDF and HD patients at baseline and 12-month. On univariable analyses Wt-SDS positively correlated with leptin and IGF-1-SDS, and negatively with DAG, while Ht-SDS of the overall cohort positively correlated with IGF1-SDS and inversely with DAG and adiponectin. On multivariable analyses, higher 12-month Ht-SDS was inversely associated with baseline DAG (beta = -0.13 per 500 higher; 95%CI -0.22, -0.04; P = .004). Higher Wt-SDS at 12-month was positively associated with HDF modality (beta = 0.47 vs HD; 95%CI 0.12-0.83; P = .01) and inversely with baseline DAG (beta = -0.18 per 500 higher; 95%CI -0.32, -0.05; P = .006). Growth Hormone (GH) treated patients receiving HDF had higher annualized increase in Ht SDS compared to those on HD.

CONCLUSIONS

In children on HD and HDF both Wt- and Ht-SDS independently correlated with lower baseline levels of the anorexygenic hormone DAG. HDF may attenuate the resistance to GH, but further studies are required to examine the mechanisms linking HDF to improved growth.

Anserine and Carnosine Induce HSP70-Dependent H2S Formation in Endothelial Cells and Murine Kidney

Anserine and carnosine have nephroprotective actions; hydrogen sulfide (H₂S) protects from ischemic tissue damage, and the underlying mechanisms are debated. In view of their common interaction with HSP70, we studied possible interactions of both dipeptides with H₂S. H₂S formation was measured in human proximal tubular epithelial cells (HK-2); three endothelial cell lines (HUVEC, HUAEC, MCEC); and in renal murine tissue of wild-type (WT), carnosinase-1 knockout (Cndp1-KO) and Hsp70-KO mice. Diabetes was induced by streptozocin. Incubation with carnosine increased H₂S synthesis capacity in tubular cells, as well as with anserine in all three endothelial cell lines. H₂S dose-dependently reduced anserine/carnosine degradation rate by serum and recombinant carnosinase-1 (CN1). Endothelial Hsp70-KO reduced H₂S formation and abolished the stimulation by anserine and could be restored by Hsp70 transfection. In female Hsp70-KO mice, kidney H₂S formation was halved. In Cndp1-KO mice, kidney anserine concentrations were several-fold and sex-specifically increased. Kidney H₂S formation capacity was increased 2-3-fold in female mice and correlated with anserine and carnosine concentrations. In diabetic Cndp1-KO mice, renal anserine and carnosine concentrations as well as H₂S formation capacity were markedly reduced compared to non-diabetic Cndp1-KO littermates. Anserine and carnosine induce H₂S formation in a cell-type and Hsp70-specific manner within a positive feedback loop with CN1.

Hyperparathyroidism Is an Independent Risk Factor for Allograft Dysfunction in Pediatric Kidney Transplantation

Introduction

Little is known about the consequences of deranged chronic kidney disease-mineral and bone disorder (CKD-MBD) parameters on kidney allograft function in children. We examined a relationship between these parameters over time and allograft outcome.

Methods

This registry study from the Cooperative European Paediatric Renal Transplant Initiative (CERTAIN) collected data at baseline, months 1, 3, 6, 9, and 12 after transplant; and every 6 months thereafter up to 5 years. Survival analysis for a composite end point of graft loss or estimated glomerular filtration rate (eGFR) ≤30 ml/min per 1.73 m² or a ≥50% decline from eGFR at month 1 posttransplant was performed. Associations of parathyroid hormone (PTH), calcium, phosphate, and 25-hydroxyvitamin D (25(OH)D) with allograft outcome were investigated using conventional stratified Cox proportional hazards models and further verified with marginal structural models with time-varying covariates.

Results

We report on 1210 patients (61% boys) from 16 European countries. The composite end point was reached in 250 grafts (21%), of which 11 (4%) were allograft losses. In the conventional Cox proportional hazards models adjusted for potential confounders, only hyperparathyroidism (hazard ratio [HR], 2.94; 95% confidence interval [CI], 1.82-4.74) and hyperphosphatemia (HR, 1.94; 95% CI, 1.28-2.92) were associated with the composite end point. Marginal structural models showed similar results for hyperparathyroidism (HR, 2.74; 95% CI, 1.71-4.38), whereas hyperphosphatemia was no longer significant (HR, 1.35; 95% CI, 0.87-2.09), suggesting that its association with graft dysfunction can be ascribed to a decline in eGFR.

Conclusion

Hyperparathyroidism is a potential independent risk factor for allograft dysfunction in children.

Molecular Mechanisms of Peritoneal Membrane Pathophysiology

The peritoneal membrane is the largest internal membrane of the human body, having a surface area that approximates the surface area of the skin [...]

How peritoneal dialysis transforms the peritoneum and vasculature in children with chronic kidney disease-what can we learn for future treatment?

Children with chronic kidney disease (CKD) suffer from inflammation and reactive metabolite-induced stress, which massively accelerates tissue and vascular aging. Peritoneal dialysis (PD) is the preferred dialysis mode in children, but currently used PD fluids contain far supraphysiological glucose concentrations for fluid and toxin removal and glucose degradation products (GDP). While the peritoneal membrane of children with CKD G5 exhibits only minor alterations, PD fluids trigger numerous molecular cascades resulting in major peritoneal membrane inflammation, hypervascularization, and fibrosis, with distinct molecular and morphological patterns depending on the GDP content of the PD fluid used. PD further aggravates systemic vascular disease. The systemic vascular aging process is particularly pronounced when PD fluids with high GDP concentrations are used. GDP induce endothelial junction disintegration, apoptosis, fibrosis, and intima thickening. This review gives an overview on the molecular mechanisms of peritoneal and vascular transformation and strategies to improve peritoneal and vascular health in patients on PD.

MO714: PARK7—A Novel Therapeutic Target for Peritoneal Dialysis Induced Peritoneal Membrane and Vascular Transformation

BACKGROUND AND AIMS

Patients with chronic kidney disease (CKD) suffer from increased oxidative stress, which is further aggravated in patients on peritoneal dialysis (PD). Parkinson disease protein 7 (PARK7) has antioxidant and antiapoptotic activity; its role in PD is unknown.

METHOD

Transcriptome and proteome data sets from microdissected omental arterioles obtained from age-matched non-CKD children, children with CKD5 and children on PD with fluids containing low or high concentrations of glucose degradation products (GDP; n = 6/group) underwent PARK7 related gene set analysis (FDR &lt; 0.05). Respective parietal peritoneal tissues (n = 60) underwent digital histomorphometry analyses. PARK7 western blotting was performed in effluents of eight children on high-GDP PD. Human umbilical endothelial cells (HUVEC) viability (MTT assay) and transepithelial electrical resistance (TER, Transwells) and 4-, 10- and 70-kDa dextran transport were measured (n = 6–12/group). As an extreme phenotype approach of PD toxicity, C57/BL6J mice were treated with chlorhexidine digluconate (CG) and PARK7 activator for 7 days and parietal peritoneal damage was quantitated (n = 6–8/group).

RESULTS

Arteriolar transcriptome analyses in children on low-GDP PD demonstrated the enrichment of PARK7 related GO terms of oxidant detoxification as compared to CKD5 and in children on high-GDP PD that of reactive oxygen species-, mitochondria- and apoptosis-related processes. On the proteome level the DNA repair/organization, catabolic and mitochondria associated processes were enriched in children on low-GDP PD, and mitochondrial processes in children on high-GDP PD.

PARK7 was detected in the parietal peritoneal tissues in mesothelial, endothelial and inflammatory cells, in myocytes and fibroblasts and was present in the PD effluents. Total peritoneal and submesothelial PARK7 abundance was similar in controls, patients with CKD5 and in patients on low-GDP PD, but 2-fold increased in patients on high GDP PD compared to controls and CKD5. Mesothelial PARK7 was 2-fold increased in children on low-GDP PD versus CKD5, endothelial PARK7 abundance was similar in all four groups.

In low-GDP PD patients endothelial PARK7 abundance correlated with vessel lumen/vessel diameter ratio (r = 0.53, P = 0.06), i.e. inversely with lumen obliteration. Submesothelial PARK7 correlated with microvessel density (r = 0.55, P = 0.05), with submesothelial hypoxia inducible factor-1 and angiopoietin-1 and -2 (ρ = 0.63, P = 0.023; r = 0.91, P &lt; 0.0001; r = 0.60, P = 0.03) but not with VEGF. Submesothelial and endothelial PARK7 correlated with respective caspase 3 abundances (r = 0.74/0.68, P = 0.009/0.015).

In HUVEC methylglyoxal (MG) dose- and time-dependently reduced viability, coincubation with PARK7 activator partially preserved endothelial cell viability. In Transwells, MG treatment decreased TER and increased dextran transport, but none of them was improved by PARK7 activation.

In mice treated with CG submesothelial thickness was 2-fold increased, microvessel density was unchanged; PARK7 protein abundance was 5-fold reduced. Co-treatment of CG with PARK7 activator prevented the submesothelial thickening.

CONCLUSION

PD modifies arteriolar PARK7 related biological processes of oxidant detoxification, mitochondria- and apoptosis-related processes. PARK7 is ubiquitously expressed in the parietal peritoneum and regulated by the GDP content of PD fluids. In patients on low-GDP PD, PARK7 abundance correlated with the degree of arteriolar lumen narrowing, and VEGF-independent angiogenesis. Activation of PARK7 preserves endothelial cell viability in vitro and prevents CG induced peritoneal membrane damage in mice and thus represents a potential novel therapeutic approach.

MO465: Molecular Mechanisms of Vascular Ageing in Children With Chronic Kidney Disease

BACKGROUND AND AIMS

Paediatric patients with chronic kidney disease (CKD) develop significant atherosclerosis and vascular calcifications until early adulthood. Largely devoid of confounding lifestyle related factors and underlying disease mostly limited to congenital abnormalities of the kidneys and urinary tract, these patients provide highly sensitive and specific information on early CKD-induced molecular mechanisms of vascular disease and on putative therapeutic targets.

METHOD

Standardized omental and parietal peritoneal tissue samples from 95 non-CKD individuals [median age 9.2 (interquartile range, IQR 15), 110 children with CKD5 (median age 8.6 (IQR 12)] underwent digital histomorphometry. Omental arterioles microdissected from surrounding fat tissue underwent whole-exome and proteome analyses, followed by gene set enrichment and Ingenuity pathway analysis. Vascular calcification pathway analysis was performed for 370 biological processes and molecular functions associated with vascular calcification extracted from Gene Ontology database. Key regulated pathways were validated by quantitative immunostaining. The effects of uraemic toxins on endothelial integrity were studied in vitro in human umbilical arterial and vein endothelial cells in Transwells.

RESULTS

Lumen to vessel diameter (L/V) ratio was reduced in patients with CKD5. Parietal peritoneal arteriole L/V ratio was 0.54 (0.2) versus 0.63 (0.1) in non-CKD controls, omental arteriole L/V ratio 0.58 (0.1) versus 0.76 (0.1) in controls (both P &lt; 0.001), indicating significant CKD5 related vascular disease. These findings were independent of underlying disease entities and gender. The parietal peritoneal submesothelial space exhibited infiltration of single CD45 positive lymphocytes, mesothelial cells which had undergone epithelial-to-mesenchymal-transition, and isolated peritoneal fibrin deposits. Submesothelial TGF-ß induced pSMAD was 4-fold increased and IL-17A 2-fold, while VEGF was not different compared to non-CKD controls.

Gene set enrichment analysis of omental arteriolar multi-omics identified enrichment of pathways including telomere extension by telomerase, chromatin histone methylation, actin cytoskeleton, integrin- and tight junction signaling, and focal adhesion in children with CKD5 children compared to controls (P &lt; 0.05). Vascular calcification pathway analysis identified 16/370 pathways significantly enriched on arteriolar transcriptome (P &lt; 0.01), related to Wnt signalling, extracellular matrix organization, complement activation, autophagy and ossification. Applying the same threshold on proteome level, 10 calcification-related arteriolar pathways were identified and included DNA damage, fatty acid metabolism, calcium ion binding, extracellular matrix organization and complement activation.

In independent age-matched cohorts, CKD5 children had shorter endothelial telomere and less endothelial methylated histone 3. The endothelial complement system was activated and arteriolar actin cytoskeleton interacting proteins gamma actin and profilin-1 were reduced in CKD5, cofilin-1 remained unchanged. In vitro, methylglyoxal and 3.4-di-deoxyglucosone-3-ene reduced transendothelial resistance, increased endothelial monolayer permeability and induced cytoskeleton disassembly (zonula occludens-1 and F-actin). These effects were prevented by co-incubation with anserine, 3-methylhistidine and alanyl-glutamine, but not by carnosine, L-histidine, 1-methylhistidine and methyl-alanyl.

CONCLUSION

CKD5 results in major vascular ageing already in early childhood. Multi-omics analysis of omental arterioles identified specific mechanisms of CKD-induced vascular ageing and of vascular calcification. Endothelial cell barrier integrity is impaired, and in vitro reversed by specific dipeptides.

FC088: Molecular and Functional Characterization of the Mesothelial and Endothelial Cell Barrier in Health, Ckd and Peritoneal Dialysis

BACKGROUND AND AIMS

Tight junctions (TJ) and transcellular ion channels and transporters define solute transport characteristics across cellular barriers, which is of particular interest in patients on peritoneal dialysis (PD). Little is known about their cell specific expression, and regulation in PD. We studied their expression in human endothelial and mesothelial cell lines and in paediatric peritoneal tissues.

METHOD

In vitro, polarized primary human peritoneal mesothelial cells (HPMC), immortalized mesothelial cells (MeT-5A), human umbilical vein endothelial cells (HUVEC) and human capillary microvascular endothelial cells (HCMEC) underwent RNA sequencing, and gene enrichment analysis (GSEA, ClueGO/Cluepedia) for functional annotation. Key findings were reconfirmed by western blotting and confocal laser scanning immunofluorescence microscopy. Transepithelial electrical resistance (TER) and permeability fluxes of fluorescent 4-, 10- and 70-kDa dextran were measured in Transwells. Ex vivo, whole transcriptome and proteome data from microdissected omental arterioles were used for targeted pathway analysis in non-CKD children, chronic kidney disease (CKD5) and on PD with low and high glucose degradation product (GDP) content (n = 6/group). Mesothelial and endothelial peritoneal solute transporting proteins were quantified in parietal peritoneum of independent paediatric non-CKD, CKD5 and PD cohorts by digital immunohistochemistry.

RESULTS

A total of 9853 of 12 760 transcripts were common between all four cell lines. A total of 631 transcripts were MeT-5A, 366 HPMC, 99 HUVEC and 87 HCMEC specific. Next to the tissue origin and transformation status, the transcripts reflected major differences in extracellular matrix, glycocalyx and adhesion organization between HCMEC and HUVEC, and extracellular matrix, migration, growth factor and immune response between HPMC and MeT-5A cells. While total counts of cell junction, transmembrane and endocytosis related transcripts were similar among cell lines, the specific TJ, transmembrane and endocytosis related transcript patterns, differed substantially between endothelial and mesothelial cells. Of the functionally well described sealing TJs, claudin (CLDN)1 was expressed in mesothelial cells, and CLDN5 in endothelial cells. Findings were reconfirmed by western blotting and immunofluorescence staining. Functionally, transepithelial resistance (TER) was 50% lower for HCMEC compared to HPMC, MeT-5A and HUVEC; 4-, 10- and 70-kDa dextran permeability was increased in HCMEC.

Ex vivo, human arteriolar pathway analysis demonstrated upregulation of paracellular transport-related pathways in CKD5 versus non-CKD patients on protein level. Compared to CKD5, low GDP PD upregulated and high GDP PD downregulated these pathways on the transcriptome and protein levels. Transcellular transporter pathway regulation was variable.

In the parietal peritoneum the endothelial surface area for transport was age dependently 1.5–2-fold higher than the mesothelial surface area and the ratio markedly increased with low GDP PD. Validation in parietal peritoneal tissues, reconfirmed arteriolar sealing TJ regulation. Arteriolar CLDN2, a paracellular pore forming cation and water transporter, correlated with D/PCreatinine (r = 0.58) and D/D0Glucose (r = –0.62), mesothelial pore forming cation transporter CLDN15 with D/PCreatinine (r = 0.57) and D/D0Glucose (–0.66). Transcellular transporters for sodium, glucose and phosphate were hardly affected by PD; phosphate transporter PIT1 abundance correlated with serum phosphate (r = –0.48).

CONCLUSION

We provide the first comprehensive analysis of the peritoneal paracellular and transcellular determinants of solute transporters and its regulation by CKD and PD. Mesothelial and endothelial cell barrier sealing and transporter abundance differed substantially, and associated with PD membrane function, with functional data suggesting a key role of both the mesothelial and endothelial cell barrier.

Angiogenic Role of Mesothelium-Derived Chemokine CXCL1 During Unfavorable Peritoneal Tissue Remodeling in Patients Receiving Peritoneal Dialysis as Renal Replacement Therapy

Peritoneal dialysis (PD) is a valuable ‘home treatment’ option, even more so during the ongoing Coronavirus pandemic. However, the long-term use of PD is limited by unfavourable tissue remodelling in the peritoneal membrane, which is associated with inflammation-induced angiogenesis. This appears to be driven primarily through vascular endothelial growth factor (VEGF), while the involvement of other angiogenic signaling pathways is still poorly understood. Here, we have identified the crucial contribution of mesothelial cell-derived angiogenic CXC chemokine ligand 1 (CXCL1) to peritoneal angiogenesis in PD. CXCL1 expression and peritoneal microvessel density were analysed in biopsies obtained by the International Peritoneal Biobank (NCT01893710 at www.clinicaltrials.gov), comparing 13 children with end-stage kidney disease before initiating PD to 43 children on chronic PD. The angiogenic potential of mesothelial cell-derived CXCL1 was assessed in vitro by measuring endothelial tube formation of human microvascular endothelial cells (HMECs) treated with conditioned medium from human peritoneal mesothelial cells (HPMCs) stimulated to release CXCL1 by treatment with either recombinant IL-17 or PD effluent. We found that the capillary density in the human peritoneum correlated with local CXCL1 expression. Both CXCL1 expression and microvessel density were higher in PD patients than in the age-matched patients prior to initiation of PD. Exposure of HMECs to recombinant CXCL1 or conditioned medium from IL-17-stimulated HPMCs resulted in increased endothelial tube formation, while selective inhibition of mesothelial CXCL1 production by specific antibodies or through silencing of relevant transcription factors abolished the proangiogenic effect of HPMC-conditioned medium. In conclusion, peritoneal mesothelium-derived CXCL1 promotes endothelial tube formation in vitro and associates with peritoneal microvessel density in uremic patients undergoing PD, thus providing novel targets for therapeutic intervention to prolong PD therapy.

Safety of Therapeutic Apheresis in Children and Adolescents

BACKGROUND

Therapeutic apheresis (TA) is based on the principles of either removing dissolved pathogenic substances (e.g., antibodies) from the blood plasma or replacing plasma factors. It expands the therapeutic scope for a variety of diseases. Safety analysis in the pediatric field are scant. The aim of this analysis was to analyze specific complications of TA modalities - plasma exchange (PE) and immunoadsorption (IA) - in children and adolescents.

METHODS

Children and adolescents (n = 298) who had received TA from 2008 to 2018 in five pediatric nephrology centers were analyzed retrospectively. In total, 4.004 treatments (2.287 PE and 1.717 IA) were evaluated.

RESULTS

Indications for TA were mainly nephrological and neurological diseases. The three main indications were antibody-mediated graft rejection (13.4%), hemolytic uremic syndrome mainly with neurological involvement (12.8%), and AB0-incompatible transplantation (11.7%). Complications developed in 440 of the 4004 sessions (11%), of which one third were non-specific (nausea, headache). IA was better tolerated than PE. Complications were reported in 9.5% (n = 163) of the IA versus 12.1% (277) of the PE sessions (p < 0.001). When considering different types of complications, significantly more non-specific/non-allergic events (p = 0.02) and allergic reactions occurred in PE sessions (p < 0.001). More complications occurred with PE, when using fresh frozen plasma (16.2%; n = 145) in comparison to human albumin (14.5%; n = 115) (p < 0.001).

CONCLUSIONS

Therapeutic apheresis in childhood and adolescence is a safe treatment procedure. IA showed a lower complication rate than PE. Therefore, IA may be preferably provided if the underlying disease pathomechanisms do not require PE.

Frequent, quantitative bone planar scintigraphy for determination of bone anabolism in growing mice

Background

To provide insight into bone turnover, quantitative measurements of bone remodeling are required. Radionuclide studies are widely used in clinical care, but have been rarely used in the exploration of the bone in preclinical studies. We describe a bone planar scintigraphy method for frequent assessment of bone activity in mice across the growing period. Since repeated venous radiotracer injections are hardly feasible in mice, we investigated the subcutaneous route.

Methods

Repeated ^99mTc-hydroxymethylene diphosphonate (HMDP) tracer bone planar scintigraphy studies of the knee region and µCT to measure femur growth rate were performed in eight mice between week 6 and week 27 of life, i.e., during their growth period. Three independent investigators assessed the regions of interest (ROI). An index was calculated based on the counts in knees ROI (normalized by pixels and seconds), corrected for the activity administered, the decay between administration and imaging, and individual weights.

Results

A total of 93 scintigraphy studies and 85 µCT were performed. Repeated subcutaneous tracer injections were well tolerated and allowed for adequate radionuclide studies. Mean scintigraphic indexes in the knees ROI decreased from 87.4 ± 2.6 × 10⁻⁶ counts s⁻¹ pixel⁻¹ MBq⁻¹ g⁻¹ at week 6 to 15.0 ± 3.3 × 10⁻⁶ counts s⁻¹ pixel⁻¹ MBq⁻¹ g⁻¹ at week 27. The time constant of the fitted exponential decay was equal to 23.5 days. As control mean femur length assessed by µCT increased from 12.2 ± 0.8 mm at week 6 to 15.8 ± 0.2 mm at week 22. The time constant of the fitted Gompertz law was equal to 26.7 days. A correlation index of −0.97 was found between femur growth and decrease of bone tracer activity count between week 6 and 24.

Conclusion

This methodological study demonstrates the potential of repeated bone planar scintigraphy in growing mice, with subcutaneous route for tracer administration, for quantitative assessment of bone remodeling.

Acute pediatric kidney replacement therapies in Europe: demographic results from the EurAKId Registry

BACKGROUND

Acute kidney injury (AKI), particularly that requiring dialysis, is a severe complication in hospitalized children associated with high morbidity and mortality. A prospective European AKI registry (EurAKId registry, NCT02960867) was created to describe the epidemiology and outcomes of pediatric patients treated with acute dialysis.

METHODS

Children were recruited who were between 0 and 18 years of age and were treated both in and outside the Pediatric Intensive Care Unit (PICU) with peritoneal dialysis (PD), hemodialysis (HD) or continuous kidney replacement therapy (CKRT) for AKI or metabolic derangement, fluid overload (FO), sepsis, or respiratory distress. Five age groups and 12 categories of primary diseases were defined.

RESULTS

Data on 340 patients were analyzed, of whom 86% received dialysis for AKI and 14% for reasons other than AKI. Boys accounted for 60% of the patients. Illness severity was greater in children with cardiac and hematologic diseases than those with kidney diseases. Most patients received dialysis in the PICU (84%). The most frequently used dialysis modality was CKRT (64%), followed by PD (14%) and HD (14%). The overall survival rate was 65%. Survival was significantly lower in children with three comorbidities than in children with no comorbidities (41% and 83%, p < 0.001).

CONCLUSIONS

The EurAKId registry is the first prospective registry considering pediatric acute kidney replacement therapies (KRT) in both critical and non-critical care settings, focusing on the three dialysis modalities in Europe. The clinical indications for KRT have expanded; our population was characterized by critically ill patients, primarily boys, who frequently received dialysis in the PICU with CKRT.

A Novel UPLC-MS/MS Method Identifies Organ-Specific Dipeptide Profiles

BACKGROUND

Amino acids have a central role in cell metabolism, and intracellular changes contribute to the pathogenesis of various diseases, while the role and specific organ distribution of dipeptides is largely unknown.

METHOD

We established a sensitive, rapid and reliable UPLC-MS/MS method for quantification of 36 dipeptides. Dipeptide patterns were analyzed in brown and white adipose tissues, brain, eye, heart, kidney, liver, lung, muscle, sciatic nerve, pancreas, spleen and thymus, serum and urine of C57BL/6N wildtype mice and related to the corresponding amino acid profiles.

RESULTS

A total of 30 out of the 36 investigated dipeptides were detected with organ-specific distribution patterns. Carnosine and anserine were most abundant in all organs, with the highest concentrations in muscles. In liver, Asp-Gln and Ala-Gln concentrations were high, in the spleen and thymus, Glu-Ser and Gly-Asp. In serum, dipeptide concentrations were several magnitudes lower than in organ tissues. In all organs, dipeptides with C-terminal proline (Gly-Pro and Leu-Pro) were present at higher concentrations than dipeptides with N-terminal proline (Pro-Gly and Pro-Leu). Organ-specific amino acid profiles were related to the dipeptide profile with several amino acid concentrations being related to the isomeric form of the dipeptides. Aspartate, histidine, proline and serine tissue concentrations correlated with dipeptide concentrations, when the amino acids were present at the C- but not at the N-terminus.

CONCLUSION

Our multi-dipeptide quantification approach demonstrates organ-specific dipeptide distribution. This method allows us to understand more about the dipeptide metabolism in disease or in healthy state.

Hemodiafiltration Is Associated With Reduced Inflammation and Increased Bone Formation Compared With Conventional Hemodialysis in Children: The HDF, Hearts and Heights (3H) Study

Background

Patients on dialysis have a high burden of bone-related comorbidities, including fractures. We report a post hoc analysis of the prospective cohort study HDF, Hearts and Heights (3H) to determine the prevalence and risk factors for chronic kidney disease-related bone disease in children on hemodiafiltration (HDF) and conventional hemodialysis (HD).

Methods

The baseline cross-sectional analysis included 144 children, of which 103 (61 HD, 42 HDF) completed 12-month follow-up. Circulating biomarkers of bone formation and resorption, inflammatory markers, fibroblast growth factor-23, and klotho were measured.

Results

Inflammatory markers interleukin-6, tumor necrosis factor-α, and high-sensitivity C-reactive protein were lower in HDF than in HD cohorts at baseline and at 12 months (P < .001). Concentrations of bone formation (bone-specific alkaline phosphatase) and resorption (tartrate-resistant acid phosphatase 5b) markers were comparable between cohorts at baseline, but after 12-months the bone-specific alkaline phosphatase/tartrate-resistant acid phosphatase 5b ratio increased in HDF (P = .004) and was unchanged in HD (P = .44). On adjusted analysis, the bone-specific alkaline phosphatase/tartrate-resistant acid phosphatase 5b ratio was 2.66-fold lower (95% confidence interval, −3.91 to −1.41; P < .0001) in HD compared with HDF. Fibroblast growth factor-23 was comparable between groups at baseline (P = .52) but increased in HD (P < .0001) and remained unchanged in HDF (P = .34) at 12 months. Klotho levels were similar between groups and unchanged during follow-up. The fibroblast growth factor-23/klotho ratio was 3.86-fold higher (95% confidence interval, 2.15–6.93; P < .0001) after 12 months of HD compared with HDF.

Conclusion

Children on HDF have an attenuated inflammatory profile, increased bone formation, and lower fibroblast growth factor-23/klotho ratios compared with those on HD. Long-term studies are required to determine the effects of an improved bone biomarker profile on fracture risk and cardiovascular health.

Lithium preserves peritoneal membrane integrity by suppressing mesothelial cell αB-crystallin

Life-saving renal replacement therapy by peritoneal dialysis (PD) is limited in use and duration by progressive impairment of peritoneal membrane integrity and homeostasis. Preservation of peritoneal membrane integrity during chronic PD remains an urgent but long unmet medical need. PD therapy failure results from peritoneal fibrosis and angiogenesis caused by hypertonic PD fluid (PDF)-induced mesothelial cytotoxicity. However, the pathophysiological mechanisms involved are incompletely understood, limiting identification of therapeutic targets. We report that addition of lithium chloride (LiCl) to PDF is a translatable intervention to counteract PDF-induced mesothelial cell death, peritoneal membrane fibrosis, and angiogenesis. LiCl improved mesothelial cell survival in a dose-dependent manner. Combined transcriptomic and proteomic characterization of icodextrin-based PDF-induced mesothelial cell injury identified αB-crystallin as the mesothelial cell protein most consistently counter-regulated by LiCl. In vitro and in vivo overexpression of αB-crystallin triggered a fibrotic phenotype and PDF-like up-regulation of vascular endothelial growth factor (VEGF), CD31-positive cells, and TGF-β-independent activation of TGF-β-regulated targets. In contrast, αB-crystallin knockdown decreased VEGF expression and early mesothelial-to-mesenchymal transition. LiCl reduced VEGF release and counteracted fibrosis- and angiogenesis-associated processes. αB-crystallin in patient-derived mesothelial cells was specifically up-regulated in response to PDF and increased in peritoneal mesothelial cells from biopsies from pediatric patients undergoing PD, correlating with markers of angiogenesis and fibrosis. LiCl-supplemented PDF promoted morphological preservation of mesothelial cells and the submesothelial zone in a mouse model of chronic PD. Thus, repurposing LiCl as a cytoprotective PDF additive may offer a translatable therapeutic strategy to combat peritoneal membrane deterioration during PD therapy.

Endothelial damage and dysfunction in acute graft-versus-host disease

Clinical studies suggested that endothelial dysfunction and damage could be involved in the development and severity of acute graft-versus-host disease (aGVHD). Accordingly, we found increased percentage of apoptotic Casp3+ blood vessels in duodenal and colonic mucosa biopsies of patients with severe aGVHD. In murine experimental aGVHD, we detected severe microstructural endothelial damage and reduced endothelial pericyte coverage accompanied by reduced expression of endothelial tight junction proteins leading to increased endothelial leakage in aGVHD target organs. During intestinal aGVHD, colonic vasculature structurally changed, reflected by increased vessel branching and vessel diameter. Because recent data demonstrated an association of endothelium-related factors and steroid refractory aGVHD (SR-aGVHD), we analyzed human biopsies and murine tissues from SR-aGVHD. We found extensive tissue damage but low levels of alloreactive T cell infiltration in target organs, providing the rationale for T-cell independent SR-aGVHD treatment strategies. Consequently, we tested the endothelium-protective PDE5 inhibitor sildenafil, which reduced apoptosis and improved metabolic activity of endothelial cells in vitro. Accordingly, sildenafil treatment improved survival and reduced target organ damage during experimental SR-aGVHD. Our results demonstrate extensive damage, structural changes, and dysfunction of the vasculature during aGVHD. Therapeutic intervention by endothelium-protecting agents is an attractive approach for SR-aGVHD complementing current anti-inflammatory treatment options.

Glucose Derivative Induced Vasculopathy in Children on Chronic Peritoneal Dialysis

[Figure: see text].

Calcium isotope fractionation by osteoblasts and osteoclasts, across endothelial and epithelial cell barriers, and with binding to proteins

Timely and accurate diagnosis of osteoporosis is essential for adequate therapy. Calcium isotope ratio (δ^44/42Ca) determination has been suggested as a sensitive, noninvasive, and radiation-free biomarker for the diagnosis of osteoporosis, reflecting bone calcium balance. The quantitative diagnostic is based on the calculation of the δ^44/42Ca difference between blood, urine, and bone. The underlying cellular processes, however, have not been studied systematically. We quantified calcium transport and δ^44/42Ca fractionation during in vitro bone formation and resorption by osteoblasts and osteoclasts and across renal proximal tubular epithelial cells (HK-2), human vein umbilical endothelial cells (HUVECs), and enterocytes (Caco-2) in transwell systems and determined transepithelial electrical resistance characteristics. δ^44/42Ca fractionation was furthermore quantified with calcium binding to albumin and collagen. Calcified matrix formed by osteoblasts was isotopically lighter than culture medium by -0.27 ± 0.03‰ within 5 days, while a consistent effect of activated osteoclasts on δ^44/42Ca could not be demonstrated. A transient increase in δ^44/42Ca in the apical compartment by 0.26‰ occured across HK-2 cells, while δ^44/42Ca fractionation was small across the HUVEC barrier and absent with Caco-2 enterocytes, and with binding of calcium to albumin and collagen. In conclusion, δ^44/42Ca fractionation follows similar universal principles as during inorganic mineral precipitation; osteoblast activity results in δ^44/42Ca fractionation. δ^44/42Ca fractionation also occurs across the proximal tubular cell barrier and needs to be considered for in vivo bone mineralization modeling. In contrast, the effect of calcium transport across endothelial and enterocyte barriers on blood δ^44/42Ca should be low and is absent with physiochemical binding of calcium to proteins.

Bone evaluation in paediatric chronic kidney disease: clinical practice points from the European Society for Paediatric Nephrology CKD-MBD and Dialysis working groups and CKD-MBD working group of the ERA-EDTA

Mineral and bone disorder (MBD) is widely prevalent in children with chronic kidney disease (CKD) and is associated with significant morbidity. CKD may cause disturbances in bone remodelling/modelling, which are more pronounced in the growing skeleton, manifesting as short stature, bone pain and deformities, fractures, slipped epiphyses and ectopic calcifications. Although assessment of bone health is a key element in the clinical care of children with CKD, it remains a major challenge for physicians. On the one hand, bone biopsy with histomorphometry is the gold standard for assessing bone health, but it is expensive, invasive and requires expertise in the interpretation of bone histology. On the other hand, currently available non-invasive measures, including dual-energy X-ray absorptiometry and biomarkers of bone formation/resorption, are affected by growth and pubertal status and have limited sensitivity and specificity in predicting changes in bone turnover and mineralization. In the absence of high-quality evidence, there are wide variations in clinical practice in the diagnosis and management of CKD-MBD in childhood. We present clinical practice points (CPPs) on the assessment of bone disease in children with CKD Stages 2-5 and on dialysis based on the best available evidence and consensus of experts from the CKD-MBD and Dialysis working groups of the European Society for Paediatric Nephrology and the CKD-MBD working group of the European Renal Association-European Dialysis and Transplant Association. These CPPs should be carefully considered by treating physicians and adapted to individual patients' needs as appropriate. Further areas for research are suggested.

Countermeasures against COVID-19: how to navigate medical practice through a nascent, evolving evidence base - a European multicentre mixed methods study

OBJECTIVES

In a previously published Delphi exercise the European Pediatric Dialysis Working Group (EPDWG) reported widely variable counteractive responses to COVID-19 during the first week of statutory public curfews in 12 European countries with case loads of 4-680 infected patients per million. To better understand these wide variations, we assessed different factors affecting countermeasure implementation rates and applied the capability, opportunity, motivation model of behaviour to describe their determinants.

DESIGN

We undertook this international mixed methods study of increased depth and breadth to obtain more complete data and to better understand the resulting complex evidence.

SETTING

This study was conducted in 14 paediatric nephrology centres across 12 European countries during the COVID-19 pandemic.

PARTICIPANTS

The 14 participants were paediatric nephrologists and EPDWG members from 12 European centres.

MAIN OUTCOME MEASURES

52 countermeasures clustered into eight response domains (access control, patient testing, personnel testing, personal protective equipment policy, patient cohorting, personnel cohorting, suspension of routine care, remote work) were categorised by implementation status, drivers (expert opinion, hospital regulations) and resource dependency. Governmental strictness and media attitude were independently assessed for each country and correlated with relevant countermeasure implementation factors.

RESULTS

Implementation rates varied widely among response domains (median 49.5%, range 20%-71%) and centres (median 46%, range 31%-62%). Case loads were insufficient to explain response rate variability. Increasing case loads resulted in shifts from expert opinion-based to hospital regulation-based decisions to implement additional countermeasures despite increased resource dependency. Higher governmental strictness and positive media attitude towards countermeasure implementation were associated with higher implementation rates.

CONCLUSIONS

COVID-19 countermeasure implementation by paediatric tertiary care centres did not reflect case loads but rather reflected heterogeneity of local rules and of perceived resources. These data highlight the need of ongoing reassessment of current practices, facilitating rapid change in 'institutional behavior' in response to emerging evidence of countermeasure efficacy.

Endurance-oriented training program with children and adolescents on maintenance hemodialysis to enhance dialysis efficacy-DiaSport

OBJECTIVE

Pediatric patients spend significant time on maintenance hemodialysis (HD) and traveling. They are often not capable of participating in sports activities. To assess the effects of exercise training during HD on dialysis efficacy in children and adolescents, we set up a multi-center randomized controlled trial (RCT).

METHODS

Patients on HD, age 6 to 18 years, were randomized either to 3× weekly bicycle ergometer training or to no training during HD for 12 weeks. Change in single-pool Kt/V (spKt/V) was the primary outcome parameter.

RESULTS

We randomized 54 patients of whom 45 qualified (23 in the intervention and 22 in the waiting control group, 14.5 ± 3.01 years, 32 male and 13 female) for the intention-to-treat (ITT) population. Only 26 patients finished study per-protocol (PP). Training was performed for an average of 11.96 weeks (0.14-13.14) at 2.08 ± 0.76 times per week and for a weekly mean of 55.52 ± 27.26 min. Single-pool Kt/V was similar in the intervention compared to the control group (1.70 [0.33] vs. 1.79 [0.55]) at V0 and (1.70 [0.36] vs. 1.71 [0.51]) at V1; secondary endpoints also showed no difference in both ITT and PP analysis. No significant adverse events were reported. No bleeding or needle dislocation occurred in 1670 training sessions.

CONCLUSIONS

Intradialytic bicycle training is safe, but does not improve dialysis efficacy and physical fitness. However, the study can be considered underpowered, particularly because of high dropout rates. Future studies need better strategies to increase motivation and compliance and other more effective/intensive exercise measures should be evaluated.

TRIAL REGISTRATION

The trial was registered in ClinicalTrials.Gov ( Clinicaltrials.gov identifier: NCT01561118) on March 22, 2012.

Enteral Ca-Intake May Be Low and Affects Serum-PTH-Levels in Pre-school Children With Chronic Kidney Disease

Treatment of chronic kidney disease (CKD) mineral bone disorder (MBD) is challenging in growing children due to the high amount of calcium needed for normal bone mineralization and the required dietary phosphate restriction, which often includes intake of calcium-rich products such as milk. Therefore, enteral calcium-intake (Ca-I) was calculated. Patients: We looked at pediatric CKD-Patients aged 0-6 years. Design: We used a retrospective analysis of Ca-I from dietary data collections. Ca-I below 60% or above 100% of the D-A-CH and the KDOQI reference values were considered as severe Ca deficiency or Ca overload, respectively. Results: We had 41 children, median age 1.1 (range 0-5.8) years, body weight 7.3 (2.4-19.9) kg, and length 68 (48-105) cm at the time of first dietary data collection. Renal function was classified as CKD stage III in 20, IV in 28, V in 44, and VD in 142 dietary data collections. At the first dietary data collection, 5 children were in the CKD stage III, 10 in IV, 9 in V, and 17 were on dialysis. Only one child progressed to a higher CKD stage. In total, 234 dietary data collections were analyzed, and 65 follow-up collections were available from 33 children after a time interval of 26 (1-372) days. The median caloric intake was 120 (47-217)% of D-A-CH RDI. In 149 (63.6%) of the dietary data collections, enteral Ca-I was below the target (<100% of the D-A-CH and KDOQI RDI). Severe Ca-deficiency was found in 11 (26%) and 4 (12%) of the children at the first and second dietary data collection, respectively. In total, 11 children were on Ca-containing phosphate binders. In dietary data collection 1 and 2, there were seven children. From these, 4/7 and 4/7 patients had an enteral total Ca-I above the 100% D-A-CH-limit or above the KDOQI limit, respectively. Absolute dietary Ca-I and Ca-I normalized to body weight correlated negatively with PTH (r = -0.196, p < 0.005 and r = -0.13, p < 0.05). Conclusion: Enteral Ca-I should repeatedly be monitored in CKD children because many may may otherwise be underexposed to enteral calcium and overexposed when calcium-containing phosphate binders are given. Our findings suggest a major impact of dietary calcium supply on bone health in pediatric CKD.

Hydrogen Sulfide and Carnosine: Modulation of Oxidative Stress and Inflammation in Kidney and Brain Axis

Emerging evidence indicates that the dysregulation of cellular redox homeostasis and chronic inflammatory processes are implicated in the pathogenesis of kidney and brain disorders. In this light, endogenous dipeptide carnosine (β-alanyl-L-histidine) and hydrogen sulfide (H₂S) exert cytoprotective actions through the modulation of redox-dependent resilience pathways during oxidative stress and inflammation. Several recent studies have elucidated a functional crosstalk occurring between kidney and the brain. The pathophysiological link of this crosstalk is represented by oxidative stress and inflammatory processes which contribute to the high prevalence of neuropsychiatric disorders, cognitive impairment, and dementia during the natural history of chronic kidney disease. Herein, we provide an overview of the main pathophysiological mechanisms related to high levels of pro-inflammatory cytokines, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and neurotoxins, which play a critical role in the kidney–brain crosstalk. The present paper also explores the respective role of H₂S and carnosine in the modulation of oxidative stress and inflammation in the kidney–brain axis. It suggests that these activities are likely mediated, at least in part, via hormetic processes, involving Nrf2 (Nuclear factor-like 2), Hsp 70 (heat shock protein 70), SIRT-1 (Sirtuin-1), Trx (Thioredoxin), and the glutathione system. Metabolic interactions at the kidney and brain axis level operate in controlling and reducing oxidant-induced inflammatory damage and therefore, can be a promising potential therapeutic target to reduce the severity of renal and brain injuries in humans.

Peritoneal Dialysis Fluid Supplementation with Alanyl-Glutamine Attenuates Conventional Dialysis Fluid-Mediated Endothelial Cell Injury by Restoring Perturbed Cytoprotective Responses

Long-term clinical outcome of peritoneal dialysis (PD) depends on adequate removal of small solutes and water. The peritoneal endothelium represents the key barrier and peritoneal transport dysfunction is associated with vascular changes. Alanyl-glutamine (AlaGln) has been shown to counteract PD-induced deteriorations but the effect on vascular changes has not yet been elucidated. Using multiplexed proteomic and bioinformatic analyses we investigated the molecular mechanisms of vascular pathology in-vitro (primary human umbilical vein endothelial cells, HUVEC) and ex-vivo (arterioles of patients undergoing PD) following exposure to PD-fluid. An overlap of 1813 proteins (40%) of over 3100 proteins was identified in both sample types. PD-fluid treatment significantly altered 378 in endothelial cells and 192 in arterioles. The HUVEC proteome resembles the arteriolar proteome with expected sample specific differences of mainly immune system processes only present in arterioles and extracellular region proteins primarily found in HUVEC. AlaGln-addition to PD-fluid revealed 359 differentially abundant proteins and restored the molecular process landscape altered by PD fluid. This study provides evidence on validity and inherent limitations of studying endothelial pathomechanisms in-vitro compared to vascular ex-vivo findings. AlaGln could reduce PD-associated vasculopathy by reducing endothelial cellular damage, restoring perturbed abundances of pathologically important proteins and enriching protective processes.

Cinacalcet use in paediatric dialysis: a position statement from the European Society for Paediatric Nephrology and the Chronic Kidney Disease-Mineral and Bone Disorders Working Group of the ERA-EDTA

Secondary hyperparathyroidism (SHPT) is an important complication of advanced chronic kidney disease (CKD) in children, which is often difficult to treat with conventional therapy. The calcimimetic cinacalcet is an allosteric modulator of the calcium-sensing receptor. It has proven to be effective and safe in adults to suppress parathyroid hormone (PTH), but data on its use in children are limited. To date, studies in children only consist of two randomized controlled trials, nine uncontrolled interventional or observational studies, and case reports that report the efficacy of cinacalcet as a PTH-lowering compound. In 2017, the European Medical Agency approved the use of cinacalcet for the treatment of SHPT in children on dialysis in whom SHPT is not adequately controlled with standard therapy. Since evidence-based guidelines are so far lacking, we present a position statement on the use of cinacalcet in paediatric dialysis patients based on the available evidence and opinion of experts from the European Society for Paediatric Nephrology, Chronic Kidney Disease-Mineral and Bone Disorder and Dialysis Working Groups, and the ERA-EDTA. Given the limited available evidence the strength of these statements are weak to moderate, and must be carefully considered by the treating physician and adapted to individual patient needs as appropriate. Audit and research recommendations to study key outcome measures in paediatric dialysis patients receiving cinacalcet are suggested.

Carnosine Activates Cellular Stress Response in Podocytes and Reduces Glycative and Lipoperoxidative Stress

Carnosine improves diabetic complications, including diabetic nephropathy, in in vivo models. To further understand the underlying mechanism of nephroprotection, we studied the effect of carnosine under glucose-induced stress on cellular stress response proteins in murine immortalized podocytes, essential for glomerular function. High-glucose stress initiated stress response by increasing intracellular heat shock protein 70 (Hsp70), sirtuin-1 (Sirt-1), thioredoxin (Trx), glutamate-cysteine ligase (gamma-glutamyl cysteine synthetase; γ-GCS) and heme oxygenase-1 (HO-1) in podocytes by 30–50% compared to untreated cells. Carnosine (1 mM) also induced a corresponding upregulation of these intracellular stress markers, which was even more prominent compared to glucose for Hsp70 (21%), γ-GCS and HO-1 (13% and 20%, respectively; all p < 0.001). Co-incubation of carnosine (1 mM) and glucose (25 mM) induced further upregulation of Hsp70 (84%), Sirt-1 (52%), Trx (35%), γ-GCS (90%) and HO-1 (73%) concentrations compared to untreated cells (all p < 0.001). The glucose-induced increase in 4-hydroxy-trans-2-nonenal (HNE) and protein carbonylation was reduced dose-dependently by carnosine by more than 50% (p < 0.001). Although podocytes tolerated high carnosine concentrations (10 mM), high carnosine levels only slightly increased Trx and γ-GCS (10% and 19%, respectively, compared to controls; p < 0.001), but not Hsp70, Sirt-1 and HO-1 proteins (p not significant), and did not modify the glucose-induced oxidative stress response. In podocytes, carnosine induced cellular stress tolerance and resilience pathways and was highly effective in reducing high-glucose-induced glycative and lipoperoxidative stress. Carnosine in moderate concentrations exerted a direct podocyte molecular protective action.

Management of children with congenital nephrotic syndrome: challenging treatment paradigms

BACKGROUND

Management of children with congenital nephrotic syndrome (CNS) is challenging. Bilateral nephrectomies followed by dialysis and transplantation are practiced in most centres, but conservative treatment may also be effective.

METHODS

We conducted a 6-year review across members of the European Society for Paediatric Nephrology Dialysis Working Group to compare management strategies and their outcomes in children with CNS.

RESULTS

Eighty children (50% male) across 17 tertiary nephrology units in Europe were included (mutations in NPHS1, n = 55; NPHS2, n = 1; WT1, n = 9; others, n = 15). Excluding patients with mutations in WT1, antiproteinuric treatment was given in 42 (59%) with an increase in S-albumin in 70% by median 6 (interquartile range: 3-8) g/L (P < 0.001). Following unilateral nephrectomy, S-albumin increased by 4 (1-8) g/L (P = 0.03) with a reduction in albumin infusion dose by 5 (2-9) g/kg/week (P = 0.02). Median age at bilateral nephrectomies (n = 29) was 9 (7-16) months. Outcomes were compared between two groups of NPHS1 patients: those who underwent bilateral nephrectomies (n = 25) versus those on conservative management (n = 17). The number of septic or thrombotic episodes and growth were comparable between the groups. The response to antiproteinuric treatment, as well as renal and patient survival, was independent of NPHS1 mutation type. At final follow-up (median age 34 months) 20 (80%) children in the nephrectomy group were transplanted and 1 died. In the conservative group, 9 (53%) remained without dialysis, 4 (24%; P < 0.001) were transplanted and 2 died.

CONCLUSION

An individualized, stepwise approach with prolonged conservative management may be a reasonable alternative to early bilateral nephrectomies and dialysis in children with CNS and NPHS1 mutations. Further prospective studies are needed to define indications for unilateral nephrectomy.