Establishment of urinary exosome-like vesicles isolation protocol for FHHNC patients and evaluation of different exosomal RNA extraction methods

Molecular and cellular pathophysiological events occurring in the majority of rare kidney diseases remain to be elucidated. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare autosomal recessive disorder caused by mutations in either CLDN16 or CLDN19 genes. This disease is characterized by massive urinary wasting of magnesium and calcium, osmosis deregulation and polyuria. Patients with p.G20D homozygous mutation in CLDN19 gene exhibit different progression to kidney failure suggesting that beyond the pathogenic mutation itself, other molecular events are favoring disease progression. Due to the fact that biopsy is not clinically indicated in these patients, urinary exosome-like vesicles (uEVs) can be envisioned as a valuable non-invasive source of information of events occurring in the kidney. Exosome research has increased notably to identify novel disease biomarkers but there is no consensus standardized protocols for uEVs isolation in patients with polyuria. For this reason, this work was aimed to evaluate and refine different uEVs isolation methods based on differential centrifugation, the gold standard method. Characterization by NTA, cryo-TEM and immunoblotting techniques identified the most appropriate protocol to obtain the highest yield and purest uEVs enriched fraction possible from urine control samples and FHHNC patients. Moreover, we tested five different RNA extraction methods and evaluated the miRNA expression pattern by qRT-PCR. In summary, we have standardized the conditions to proceed with the identification of differentially expressed miRNAs in uEVs of FHHNC patients, or other renal diseases characterized by polyuria

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

Allograft outcome; Hyperparathyroidism; Kidney transplantationResultado del aloinjerto; Hiperparatiroidismo; Trasplante de riñónResultat de l'aloempelt; Hiperparatiroïdisme; Trasplantament de ronyóIntroduction 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.This study was supported by a research grant from the European Society for Paediatric Nephrology to AP. The authors gratefully acknowledge the funding of the Cooperative European Paediatric Renal Transplant Initiative Registry by a grant from the Dietmar Hopp Stiftung, the European Society for Paediatric Nephrology, and the German Society for Paediatric Nephrology and by grants from the pharmaceutical companies Astellas and Novartis

Long-Term Efficacy and Safety of the Long-Acting Complement C5 Inhibitor Ravulizumab for the Treatment of Atypical Hemolytic Uremic Syndrome in Adults

Hemolytic uremic syndrome; Kidney failure; RavulizumabSíndrome hemolítico urémico; Insuficiencia renal; RavulizumabSíndrome hemolític urèmic; Insuficiència renal; RavulizumabIntroduction Atypical hemolytic uremic syndrome (aHUS) is a rare, complex, multisystem disease of dysregulated complement activity, characterized by progressive thrombotic microangiopathy (TMA), acute kidney injury, and multiorgan dysfunction, which often progresses to chronic kidney disease. Results from the prospective clinical trial of ravulizumab (NCT02949128) reveal rapid resolution of TMA in patients with aHUS, with sustained efficacy and safety in a 26-week initial evaluation period. Methods The aim of this analysis was to characterize the long-term efficacy and the safety profile of ravulizumab in adults with aHUS who had completed the initial evaluation period of the trial. Complete TMA response, hematologic and kidney functions, and safety were evaluated for all patients available for follow-up in the extension period (median follow-up: 76.7 weeks; range: 0.6–118.3). This trial included a total of 58 patients, 49 of whom entered the extension period. Results A total of 4 additional patients achieved complete TMA response during the follow-up period. Normalization of platelet count, serum lactate dehydrogenase (LDH), and hemoglobin observed in the 26-week initial evaluation period was sustained until the last available follow-up, as were the improvements in the estimated glomerular filtration rate (eGFR) and patient quality of life. All efficacy endpoints were correlated with the sustained inhibition of complement C5. Most adverse events (AEs) occurred early during the initial evaluation period and decreased substantially during the extension period. No patient developed a meningococcal infection or died during the extension period. Conclusion This analysis reveals that ravulizumab administered every 8 weeks is efficacious with an acceptable safety profile for the long-term treatment of adults with aHUS and provides additional clinical benefit beyond 6 months of treatment

Newborn Screening: Review of its Impact for Cystinosis

Clinical course; Infantile nephropathic cystinosis; Newborn screeningCurso clínico; Cistinosis nefropática infantil; Cribado de recién nacidosCurs clínic; Cistinosi nefropàtica infantil; Cribratge de nounatsNewborn screening (NBS) programmes are considered to be one of the most successful secondary prevention measures in childhood to prevent or reduce morbidity and/or mortality via early disease identification and subsequent initiation of therapy. However, while many rare diseases can now be detected at an early stage using appropriate diagnostics, the introduction of a new target disease requires a detailed analysis of the entire screening process, including a robust scientific background, analytics, information technology, and logistics. In addition, ethics, financing, and the required medical measures need to be considered to allow the benefits of screening to be evaluated at a higher level than its potential harm. Infantile nephropathic cystinosis (INC) is a very rare lysosomal metabolic disorder. With the introduction of cysteamine therapy in the early 1980s and the possibility of renal replacement therapy in infancy, patients with cystinosis can now reach adulthood. Early diagnosis of cystinosis remains important as this enables initiation of cysteamine at the earliest opportunity to support renal and patient survival. Using molecular technologies, the feasibility of screening for cystinosis has been demonstrated in a pilot project. This review aims to provide insight into NBS and discuss its importance for nephropathic cystinosis using molecular technologies

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

COVID-19; Política de salut; NefrologiaCOVID-19; Política de salud; NefrologiaCOVID-19; Nealth policy; NephrologyObjectives 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.The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors

Multi-population genome-wide association study implicates immune and non-immune factors in pediatric steroid-sensitive nephrotic syndrome

Genetics; Minimal change disease; Paediatric kidney diseaseGenética; Enfermedad de cambios mínimos; Enfermedad renal pediátricaGenètica; Malaltia de canvis mínims; Malaltia renal pediàtricaPediatric steroid-sensitive nephrotic syndrome (pSSNS) is the most common childhood glomerular disease. Previous genome-wide association studies (GWAS) identified a risk locus in the HLA Class II region and three additional independent risk loci. But the genetic architecture of pSSNS, and its genetically driven pathobiology, is largely unknown. Here, we conduct a multi-population GWAS meta-analysis in 38,463 participants (2440 cases). We then conduct conditional analyses and population specific GWAS. We discover twelve significant associations-eight from the multi-population meta-analysis (four novel), two from the multi-population conditional analysis (one novel), and two additional novel loci from the European meta-analysis. Fine-mapping implicates specific amino acid haplotypes in HLA-DQA1 and HLA-DQB1 driving the HLA Class II risk locus. Non-HLA loci colocalize with eQTLs of monocytes and numerous T-cell subsets in independent datasets. Colocalization with kidney eQTLs is lacking but overlap with kidney cell open chromatin suggests an uncharacterized disease mechanism in kidney cells. A polygenic risk score (PRS) associates with earlier disease onset. Altogether, these discoveries expand our knowledge of pSSNS genetic architecture across populations and provide cell-specific insights into its molecular drivers. Evaluating these associations in additional cohorts will refine our understanding of population specificity, heterogeneity, and clinical and molecular associations.K.I., K.N., and K.T. were supported by the Japan Agency for Medical Research and Development (AMED) under grant number JP17km0405108h0005. K.T. was supported by the Japan Agency for Medical Research and Development (AMED) under grants JP17km0405205h0002 and 18km0405205h0003. K.I., T.H., C.N., and K.N. were supported by the Japan Society for the Promotion of Science (JSPS) under Grant-in-Aid for Scientific Research fostering Joint International Research (B) 18KK0244. K.I., X.J., T.H., C.N., and K.N. were supported by the Japan Society for the Promotion of Science (JSPS) under Grant-in-Aid for Scientific Research fostering Joint International Research (B) 21KK0147. This work is supported by the Department of Defense (PR190746, PR212415) to S.S-C., by the National Center for Advancing Translational Sciences, National Institutes of Health (Grant Number UL1TR001873) to S.S-C., and by the National Institute of Health Grant RC2DK122397, M.Sam, S.S-C., M.R.P., and F.H. A.M. received support from the American Society of Nephrology KidneyCure Ben J. Lipps Research Fellowship. Y.G. received support from the NEPTUNE Career Development Award. P.R. and H.D. were funded by European Research Council grant ERC-2012- ADG_20120314 (grant agreement 322947) and Agence Nationale pour la Recherche “Genetransnephrose” grant ANR-16-CE17-004-01. M.Sam. was supported by NIH grants R01DK119380, 2U54DK083912, and a gift from The Pura Vida Kidney Foundation. The Nephrotic Syndrome Study Network (NEPTUNE) is part of the Rare Diseases Clinical Research Network (RDCRN), which is funded by the National Institutes of Health (NIH) and led by the National Center for Advancing Translational Sciences (NCATS) through its Division of Rare Diseases Research Innovation (DRDRI). NEPTUNE is funded under grant number U54DK083912 as a collaboration between NCATS and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Additional funding and/or programmatic support is provided by the University of Michigan, NephCure Kidney International, and the Halpin Foundation. RDCRN consortia are supported by the RDCRN Data Management and Coordinating Center (DMCC), funded by NCATS and the National Institute of Neurological Disorders and Stroke (NINDS) under U2CTR002818. The authors wish to thank Seong Kyu Han, Ph.D. (Boston Children’s Hospital and Harvard Medical School) for his assistance in creating figures

The European Rare Kidney Disease Registry (ERKReg): objectives, design and initial results

Epidemiologia; Nefrologia pediàtrica; RegistreEpidemiología; Nefrología pediátrica; RegistroEpidemiology; Pediatric nephrology; RegistryBackground The European Rare Kidney Disease Reference Network (ERKNet) recently established ERKReg, a Web-based registry for all patients with rare kidney diseases. The main objectives of this core registry are to generate epidemiological information, identify current patient cohort for clinical research, explore diagnostic and therapeutic management practices, and monitor treatment performance and patient’s outcomes. The registry has a modular design that allows to integrate comprehensive disease-specific registries as extensions to the core database. The diagnosis (Orphacode) and diagnostic information (clinical, imaging, histopathological, biochemical, immunological and genetic) are recorded. Anthropometric, kidney function, and disease-specific management and outcome items informing a set of 61 key performance indicators (KPIs) are obtained annually. Data quality is ensured by automated plausibility checks upon data entry and regular offline database checks prompting queries. Centre KPI statistics and benchmarking are calculated automatically. Results Within the first 24 months since its launch, 7607 patients were enrolled to the registry at 45 pediatric and 12 specialized adult nephrology units from 21 countries. A kidney disease diagnosis had been established in 97.1% of these patients at time of enrolment. While 199 individual disease entities were reported by Orphacode, 50% of the cohort could be classified with 11, 80% with 43 and 95% with 92 codes. Two kidney diagnoses were assigned in 6.5% of patients; 5.9% suffered from syndromic disease. Whereas glomerulopathies (54.8%) and ciliopathies including autosomal dominant polycystic kidney disease (ADPKD) (31.5%) were the predominant disease groups among adults, the pediatric disease spectrum encompassed congenital anomalies of the kidney and urinary tract (CAKUT) (33.7%), glomerulopathies (30.7%), ciliopathies (14.0%), tubulopathies (9.2%), thrombotic microangiopathies (5.6%), and metabolic nephropathies (4.1%). Genetically confirmed diagnoses were reported in 24% of all pediatric and 12% adult patients, whereas glomerulopathies had been confirmed by kidney biopsy in 80.4% adult versus 38.5% pediatric glomerulopathy cases. Conclusions ERKReg is a rapidly growing source of epidemiological information and patient cohorts for clinical research, and an innovative tool to monitor management quality and patient outcomes.Open Access funding enabled and organized by Projekt DEAL. The ERKReg project was made possible by a European Union grant (Chafea #777303) within the Third Health Programme “ERN-2016—Framework Partnership Agreement 2017–2021”. Additional support was received by ERKNet within the same framework. Further support for the development of the registry was kindly provided by the ERA-EDTA Workgroup for Inherited Kidney Diseases (WGIKD)

Expert guidance on the multidisciplinary management of cystinosis in adolescent and adult patients

Clinical recommendations; Cystinosis; Multidisciplinary careRecomendaciones clínicas; Cistinosis; Atención multidisciplinariaRecomanacions clíniques; Cistinosi; Atenció multidisciplinàriaCystinosis, a rare autosomal recessive lysosomal storage disorder, results in an abnormal accumulation of the amino acid cystine in multiple organs and tissues of the body. Renal symptoms typically develop in the first few months of life, with extra-renal manifestations becoming apparent over the next 10–20 years, which require coordinated multidisciplinary care. Here, we describe a consensus-based guidance to support the management of adolescents and adults living with cystinosis. The programme was led by a Steering Committee (SC) of six experts in the management of patients with cystinosis, who identified a list of 15 key questions reflecting the multi-organ effects of cystinosis. An Extended Faculty (EF) of eight additional specialists was invited to answer the questions via an online digital platform using a quasi-Delphi approach. The consolidated answers were summarized into recommendations. Where evidence was lacking, recommendations were developed using collective expert consensus. The EF was asked to agree/disagree with the clinical recommendations. The expert-agreed clinical recommendations provide guidance that considers both renal and extra-renal systems. The topics covered are advice on fertility and family planning, consideration of the nervous, muscular, ophthalmic, cardio-respiratory, endocrine, dermatological and gastrointestinal systems, as well as guidance on dental care, diet, lifestyle, and improving quality of life and psychological well-being. In summary, this work outlines recommendations and a checklist for clinicians with a vision for improving and standardizing the multidisciplinary care for patients with cystinosis.The programme was supported by Chiesi Farmaceutici Spa. Chiesi was not involved in the content or outcomes of the programme which were solely determined by the SC and extended faculty experts

Parathyroid hormone and phosphate homeostasis in patients with Bartter and Gitelman syndrome: an international cross-sectional study

Bartter syndrome; Parathyroid hormone; PhosphateSíndrome de Bartter; Hormona paratiroidea; FosfatoSíndrome de Bartter; Hormona paratiroïdal; FosfatBackground Small cohort studies have reported high parathyroid hormone (PTH) levels in patients with Bartter syndrome and lower serum phosphate levels have anecdotally been reported in patients with Gitelman syndrome. In this cross-sectional study, we assessed PTH and phosphate homeostasis in a large cohort of patients with salt-losing tubulopathies. Methods Clinical and laboratory data of 589 patients with Bartter and Gitelman syndrome were provided by members of the European Rare Kidney Diseases Reference Network (ERKNet) and the European Society for Paediatric Nephrology (ESPN). Results A total of 285 patients with Bartter syndrome and 304 patients with Gitelman syndrome were included for analysis. Patients with Bartter syndrome type I and II had the highest median PTH level (7.5 pmol/L) and 56% had hyperparathyroidism (PTH >7.0 pmol/L). Serum calcium was slightly lower in Bartter syndrome type I and II patients with hyperparathyroidism (2.42 versus 2.49 mmol/L; P = .038) compared to those with normal PTH levels and correlated inversely with PTH (rs −0.253; P = .009). Serum phosphate and urinary phosphate excretion did not correlate with PTH. Overall, 22% of patients had low serum phosphate levels (phosphate—standard deviation score < −2), with the highest prevalence in patients with Bartter syndrome type III (32%). Serum phosphate correlated with tubular maximum reabsorption of phosphate/glomerular filtration rate (TmP/GFR) (rs 0.699; P < .001), suggesting renal phosphate wasting. Conclusions Hyperparathyroidism is frequent in patients with Bartter syndrome type I and II. Low serum phosphate is observed in a significant number of patients with Bartter and Gitelman syndrome and appears associated with renal phosphate wasting.This project has been supported by the European Reference Network for Rare Kidney Diseases (ERKNet), which is partly co-funded by the European Union within the framework of the Third Health Programme ‘ERN-2016-Framework Partnership Agreement 2017–2021’. This work is generated within the European Society for Paediatric Nephrology working group on inherited renal disorders. This work was supported by an Innovation Grant 19OI06 from the Dutch Kidney Foundation (to T.N.)

ePHex: a phase 3, double-blind, placebo-controlled, randomized study to evaluate long-term efficacy and safety of Oxalobacter formigenes in patients with primary hyperoxaluria

Oxabact; Oxalobacter formigenes; Primary hyperoxaluriaOxabact; Oxalobacter formigenes; Hiperoxaluria primariaOxabact; Oxalobacter formigenes; Hiperoxalúria primàriaBackground Primary hyperoxalurias (PHs) are rare genetic diseases that increase the endogenous level of oxalate, a waste metabolite excreted predominantly by the kidneys and also the gut. Treatments aim to improve oxalate excretion, or reduce oxalate generation, to prevent kidney function deterioration. Oxalobacter formigenes is an oxalate metabolizing bacterium. This Phase III, double-blind, placebo-controlled randomized trial investigated the effectiveness of orally administered Oxabact™, a lyophilized O. formigenes formulation, at reducing plasma oxalate levels in patients suffering from PH. Methods Subjects (≥ 2 years of age) with a diagnosis of PH and maintained but suboptimal kidney function (mean estimated glomerular filtration rate at baseline < 90 mL/min/1.73 m2) were eligible to participate. Subjects were randomized to receive Oxabact or placebo twice daily for 52 weeks. Change from baseline in plasma oxalate concentration at Week 52 was the primary study endpoint. Results Forty-three subjects were screened, 25 were recruited and one was discontinued. At Week 52, O. formigenes was established in the gut of subjects receiving Oxabact. Despite decreasing plasma oxalate level in subjects treated with Oxabact, and stable/increased levels with placebo, there was no significant difference between groups in the primary outcome (Least Squares mean estimate of treatment difference was − 3.80 μmol/L; 95% CI: − 7.83, 0.23; p-value = 0.064). Kidney function remained stable in both treatments. Conclusions Oxabact treatment may have stabilized/reduced plasma oxalate versus a rise with placebo, but the difference over 12 months was not statistically significant (p = 0.06). A subtle effect observed with Oxabact suggests that O. formigenes may aid in preventing kidney stones.The study was designed, funded, and managed by OxThera Intellectual Property AB (Stockholm, Sweden)