Improved prenatal assessment of kidney disease using multiple ultrasound features.

BACKGROUND AND HYPOTHESIS: Congenital anomalies of the kidney and the urinary tract (CAKUT), often discovered in utero, cover a wide spectrum of outcomes ranging from normal postnatal kidney function to fetal death. The current ultrasound workup does not allow for an accurate assessment of the outcome. The present study aimed to significantly improve the ultrasound-based prediction of postnatal kidney survival in CAKUT. METHODS: Histological analysis of kidneys of 15 CAKUT fetuses was performed to better standardize the ultrasound interpretation of dysplasia and cysts. Ultrasound images of 140 CAKUT fetuses with 2-year postnatal follow-up were annotated for amniotic fluid volume and kidney number, size, dysplasia and/or cysts using standardized ultrasound readout. Association of ultrasound features and clinical data (sex and age at diagnosis) with postnatal kidney function was studied using logistic regression. Amniotic fluid proteome associated to kidney dysplasia or cysts was characterized by mass spectrometry. RESULTS: Histologically, poor ultrasound corticomedullary differentiation was associated to dysplastic lesions and ultrasound hyperechogenicity was associated to the presence of microcysts. Of all ultrasound and clinical parameters, reduced amniotic volume, dysplasia and cysts were the best predictors of poor outcome (Odd ratio = 57 [95%CI: 11-481], 20 [3-225] and 7 [1-100], respectively). Their combination into an algorithm improved prediction of postnatal kidney function compared to amniotic volume alone (area under the ROC curve = 0.92 [0.86-0.98] in a 10-fold cross validation). Dysplasia and cysts were correlated (Cramer's V coefficient = 0.44, p<0.0001), but amniotic fluid proteome analysis revealed that they had distinct molecular origin (extracellular matrix and cell contacts versus cellular death, respectively), probably explaining the additivity of their predictive performances. CONCLUSION: Antenatal clinical advice for CAKUT pregnancies can be improved by a more standardized and combined interpretation of ultrasound data.

Outcome of immunosuppression in children with IgA vasculitis-related nephritis.

BACKGROUND AND HYPOTHESIS: IgA vasculitis with nephritis (IgAVN) is the most common vasculitis in children. Treatment recommendations are, due to a lack of evidence, based on expert opinion resulting in variation. The aim of this study was to describe clinical presentation, treatment and outcome of an extremely large cohort of children with biopsy proven IgAVN to identify prognostic risk factors and signals of treatment efficacy. METHODS: Retrospective data were collected on 1148 children with biopsy proven IgAVN between 2005 and 2019 from 41 international paediatric nephrology centres across 25 countries and analyzed using multivariate analysis. The primary outcome was estimated glomerular filtration rate (eGFR) and persistent proteinuria at last follow up. RESULTS: The median follow up was 3.7 years (IQR 2-6.2). At last follow up, 29% of patients had an eGFR < 90 ml/min/1.73m2, 36% had proteinuria and 3% had chronic kidney disease stage 4-5. Older age, lower eGFR at onset, hypertension and histological features of tubular atrophy and segmental sclerosis were predictors of poor outcome. There was no evidence to support any specific second line immunosuppressive regimen to be superior to others, even when further analysing subgroups of children with reduced kidney function, nephrotic syndrome or hypoalbuminemia at onset. Delayed start of immunosuppressive treatment was associated with a lower eGFR at last follow up. CONCLUSION: In this large retrospective cohort, key features associated with disease outcome are highlighted. Importantly there was no evidence to support that any specific immunosuppressive treatments were superior to others. Further discovery science and well-conducted clinical trials are needed to define accurate treatment and improve outcomes of IgAVN.

Pediatric urogenital schistosomiasis diagnosed in France.

BACKGROUND: Schistosomiasis affects approximately 230 million people worldwide. There is an increased incidence of schistosomiasis cases in France acquired from outside the country. This increases the risk of schistosomiasis outbreaks as observed in Corsica. Clinicians from non-endemic regions are not accustomed to diagnosing and managing this pathology. The objective of this study is to provide a better description of the clinical and paraclinical characteristics and disease evolution of affected children. METHODS: Through the French Pediatric Nephrology Society and the Pediatric Infectious Pathology Group, we contacted all French pediatric centers that may have treated children with urinary schistosomiasis between 2013 and 2019. Age, sex, comorbidities, and clinical, biological, and radiological data (at discovery and follow-up) were collected retrospectively. RESULTS: A total of 122 patients from 10 different centers were included. The median age was 14 years and the sex ratio M/F was 4:1. Hematuria was present in 82% of the patients while urinary tract abnormality was found in 36% of them. Fourteen patients (11%) displayed complicated forms of urinary schistosomiasis including 10 patients with chronic kidney disease. A total of 110 patients received treatment with praziquantel, which was well-tolerated and led to clinical resolution of symptoms in 98% of cases. CONCLUSION: Patients with schistosomiasis present frequent kidney, urinary, or genital involvement. Systematic screening of patients returning from endemic areas is therefore recommended, especially since treatment with antiparasitic drugs is effective and well-tolerated. Enhancing medical knowledge of this pathology among all practitioners is essential to improve care and outcomes.

Pediatric ANCA vasculitis: clinical presentation, treatment, and outcomes in a French retrospective study.

BACKGROUND: Pediatric ANCA vasculitis is a rare group of diseases with a scarcity of data in children. Annual incidence appeared to increase in the last several years, placing higher interest in the clinical and therapeutical outcomes of the disorder. Also, the growing use of rituximab questions the latest outcomes in these diseases. We therefore conducted a retrospective study to better understand the current characteristics, management, and the latest outcomes of the disorder. METHODS: We conducted a 9-year retrospective study of 46 children in 14 different centers across France to describe their clinical and laboratory presentations, therapeutic regimens, and kidney outcome. RESULTS: P-ANCA appeared to be a potential marker for higher relapse risk. Compared to adults, we found that ear-nose-throat presentations were frequent (45.7%) and more severe. Despite an evolution in the treatment management, kidney outcome remained poor with a substantial proportion of chronic kidney disease (54.8% at 1 year). Mortality stays low with 3 patients (6.5%) deceased at the end of our study. CONCLUSION: Clinical presentation was as previously described and time to diagnosis remains long. P-ANCA is a statistically significant marker for increased relapse risk. We observed a modification in the treatment regimens over the past several years with a growing use of rituximab and a decreasing use of cyclophosphamide. Despite these changes, kidney outcome remains poor and prospective studies should be conducted to assess the most appropriate therapeutic modality for each patient. A higher resolution version of the Graphical abstract is available as Supplementary information.

Outcome of children with IgA vasculitis with nephritis treated with steroids: a matched controlled study.

BACKGROUND: IgA vasculitis (IgAV) is the most common vasculitis in children. IgAV long-term prognosis depends on kidney involvement or IgA vasculitis with nephritis (IgAVN). To date, steroid treatment (oral steroids or methylprednisolone pulses) has not proven to be formally efficient. This study aimed to assess the role of steroids on IgAVN outcome. METHODS: All children with IgAVN diagnosed 2000-2019 in 14 French pediatric nephrology units with minimal follow-up of 6 months were retrospectively included. Outcomes of patients treated with steroids were compared with those of a control group of untreated patients matched for age, sex, proteinuria, eGFR, and histological features. The primary endpoint was IgAVN remission defined as urine protein-to-creatinine ratio < 20 mg/mmol without impaired eGFR one year after disease onset. RESULTS: A total of 359 patients with IgAVN were included with a median follow-up time of 249 days (range 43-809). One hundred eight (30%) patients received oral steroids alone, 207 (51%) patients received three methylprednisolone pulses followed by oral steroids, and 44 patients (12.5%) did not receive steroids. Thirty-two children treated with oral steroids alone were compared with 32 matched control patients who did not receive steroids. One year after disease onset, IgAVN remission proportion was not different between these two groups: 62% versus 68%, respectively. Ninety-three children treated with oral steroids alone were compared with 93 matched patients treated with three methylprednisolone pulses followed by oral corticosteroids. IgAVN remission proportion was not different between these two groups: 77% versus 73%, respectively. CONCLUSION: The benefit of oral steroids alone and methylprednisolone pulses could not be established based on this observational study. Randomized controlled trials are thus required to determine the efficacy of steroids in IgAVN. A higher resolution version of the Graphical abstract is available as Supplementary information.

Gitelman-Like Syndrome Caused by Pathogenic Variants in mtDNA.

BACKGROUND: Gitelman syndrome is the most frequent hereditary salt-losing tubulopathy characterized by hypokalemic alkalosis and hypomagnesemia. Gitelman syndrome is caused by biallelic pathogenic variants in SLC12A3, encoding the Na+-Cl- cotransporter (NCC) expressed in the distal convoluted tubule. Pathogenic variants of CLCNKB, HNF1B, FXYD2, or KCNJ10 may result in the same renal phenotype of Gitelman syndrome, as they can lead to reduced NCC activity. For approximately 10 percent of patients with a Gitelman syndrome phenotype, the genotype is unknown. METHODS: We identified mitochondrial DNA (mtDNA) variants in three families with Gitelman-like electrolyte abnormalities, then investigated 156 families for variants in MT-TI and MT-TF, which encode the transfer RNAs for phenylalanine and isoleucine. Mitochondrial respiratory chain function was assessed in patient fibroblasts. Mitochondrial dysfunction was induced in NCC-expressing HEK293 cells to assess the effect on thiazide-sensitive 22Na+ transport. RESULTS: Genetic investigations revealed four mtDNA variants in 13 families: m.591C>T (n=7), m.616T>C (n=1), m.643A>G (n=1) (all in MT-TF), and m.4291T>C (n=4, in MT-TI). Variants were near homoplasmic in affected individuals. All variants were classified as pathogenic, except for m.643A>G, which was classified as a variant of uncertain significance. Importantly, affected members of six families with an MT-TF variant additionally suffered from progressive chronic kidney disease. Dysfunction of oxidative phosphorylation complex IV and reduced maximal mitochondrial respiratory capacity were found in patient fibroblasts. In vitro pharmacological inhibition of complex IV, mimicking the effect of the mtDNA variants, inhibited NCC phosphorylation and NCC-mediated sodium uptake. CONCLUSION: Pathogenic mtDNA variants in MT-TF and MT-TI can cause a Gitelman-like syndrome. Genetic investigation of mtDNA should be considered in patients with unexplained Gitelman syndrome-like tubulopathies.

Hepatocyte nuclear factor-1ß shapes the energetic homeostasis of kidney tubule cells.

Energetic metabolism controls key steps of kidney development, homeostasis, and epithelial repair following acute kidney injury (AKI). Hepatocyte nuclear factor-1ß (HNF-1ß) is a master transcription factor that controls mitochondrial function in proximal tubule (PT) cells. Patients with HNF1B pathogenic variant display a wide range of kidney developmental abnormalities and progressive kidney fibrosis. Characterizing the metabolic changes in PT cells with HNF-1ß deficiency may help to identify new targetable molecular hubs involved in HNF1B-related kidney phenotypes and AKI. Here, we combined 1 H-NMR-based metabolomic analysis in a murine PT cell line with CrispR/Cas9-induced Hnf1b invalidation (Hnf1b-/- ), clustering analysis, targeted metabolic assays, and datamining of published RNA-seq and ChIP-seq dataset to identify the role of HNF-1ß in metabolism. Hnf1b-/- cells grown in normoxic conditions display intracellular ATP depletion, increased cytosolic lactate concentration, increased lipid droplet content, failure to use pyruvate for energetic purposes, increased levels of tricarboxylic acid (TCA) cycle intermediates and oxidized glutathione, and a reduction of TCA cycle byproducts, all features consistent with mitochondrial dysfunction and an irreversible switch toward glycolysis. Unsupervised clustering analysis showed that Hnf1b-/- cells mimic a hypoxic signature and that they cannot furthermore increase glycolysis-dependent energetic supply during hypoxic challenge. Metabolome analysis also showed alteration of phospholipid biosynthesis in Hnf1b-/- cells leading to the identification of Chka, the gene coding for choline kinase α, as a new putative target of HNF-1ß. HNF-1ß shapes the energetic metabolism of PT cells and HNF1B deficiency in patients could lead to a hypoxia-like metabolic state precluding further adaptation to ATP depletion following AKI.

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

BACKGROUND: 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.

Mapping of the amniotic fluid proteome of fetuses with congenital anomalies of the kidney and urinary tract identifies plastin 3 as a protein involved in glomerular integrity.

Congenital anomalies of the kidney and the urinary tract (CAKUT) are the first cause of chronic kidney disease in childhood. Several genetic and environmental origins are associated with CAKUT, but most pathogenic pathways remain elusive. Considering the amniotic fluid (AF) composition as a proxy for fetal kidney development, we analyzed the AF proteome from non-severe CAKUT (n = 19), severe CAKUT (n = 14), and healthy control (n = 22) fetuses using LC-MS/MS. We identified 471 significant proteins that discriminated the three AF groups with 81% precision. Among them, eight proteins independent of gestational age (CSPG4, LMAN2, ENDOD1, ANGPTL2, PRSS8, NGFR, ROBO4, PLS3) were associated with both the presence and the severity of CAKUT. Among those, five were part of a protein-protein interaction network involving proteins previously identified as being potentially associated with CAKUT. The actin-bundling protein PLS3 (plastin 3) was the only protein displaying a gradually increased AF abundance from control, via non-severe, to severe CAKUT. Immunohistochemistry experiments showed that PLS3 was expressed in the human fetal as well as in both the fetal and the postnatal mouse kidney. In zebrafish embryos, depletion of PLS3 led to a general disruption of embryonic growth including reduced pronephros development. In postnatal Pls3-knockout mice, kidneys were macroscopically normal, but the glomerular ultrastructure showed thickening of the basement membrane and fusion of podocyte foot processes. These structural changes were associated with albuminuria and decreased expression of podocyte markers including Wilms' tumor-1 protein, nephrin, and podocalyxin. In conclusion, we provide the first map of the CAKUT AF proteome that will serve as a reference for future studies. Among the proteins strongly associated with CAKUT, PLS3 did surprisingly not specifically affect nephrogenesis but was found as a new contributor in the maintenance of normal kidney function, at least in part through the control of glomerular integrity. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

To biopsy or not to biopsy: Henoch-Schönlein nephritis in children, a 5-year follow-up study.

BACKGROUND: The prognosis of Henoch-Schönlein purpura (HSP), IgA vasculitis, depends on kidney involvement. There is no consensus on the initiation of treatment for HSP nephritis (HSPN). Some centres start treatment before performing a kidney biopsy (KB) while in others, treatment is dictated by the importance of the clinical, biological and histological signs. The aim of this study was to evaluate which of these two approaches is associated with a better kidney outcome at 5-year follow-up. METHODS: This multicentre, retrospective, nonrandomised study included children treated for HSPN between 2006 and 2010 in a French paediatric nephrology unit. One group had an early KB at diagnosis (before starting treatment or in the 15 following days). In the second group, initial treatment was decided without performing a KB. RESULTS: Among the 107 children included, 63.5% had an early KB at diagnosis. Follow-up at 5 years was completed in 44 children (28 KB at diagnosis, 16 no KB at diagnosis). Median urine protein/creatinine at 5 years was 2.5 mg/mmol in the early biopsy diagnosis group and 12.5 mg/mmol in the non-biopsy group. An antiproteinuric treatment was given, at 5 years, to 35.7% of the early biopsy at diagnosis children and in 62.5% of the non-biopsied children. CONCLUSIONS: Children with early KB at diagnosis seem to have a better renal outcome at 5 years compared to those without an early biopsy at diagnosis or biopsied later. However, this is a small patient cohort and data are missing. Further work is needed to build consensual guidelines on the management of HSPN in children.

Benign and malignant proliferation in idiopathic nephrotic syndrome: a French cohort study.

BACKGROUND: There seems to be a possible link between nephrotic syndrome (NS) and lymphoproliferative syndrome, but it remains poorly understood. METHODS: This multicentric and retrospective study focuses on children, who developed idiopathic NS and malignant or benign proliferation between 2000 and 2021. RESULTS: Eleven patients were included, with a median age of 4 years. Only one had a steroid-resistant nephrotic syndrome (SRNS). The maintenance therapy before the proliferation was in majority tacrolimus or mycophenolate mofetil (MMF), but three patients did not receive treatments. The proliferation was mainly a Hodgkin's lymphoma (45%) or a lymphoproliferative disease (36%), in a median time after the NS of two years. Viruses were found in seven cases (EBV in five cases and HHV-8 in two). CONCLUSION: The association between proliferative syndrome and idiopathic NS may not be fortuitous, possibly with a common lymphocytic disturbance. Genetic analyses could improve the comprehension of these manifestations in the future. A higher resolution version of the Graphical abstract is available as Supplementary information.

Mycophenolic acid area under the concentration-time curve is associated with therapeutic response in childhood-onset lupus nephritis.

BACKGROUND: Mycophenolic acid (MPA), the active compound of mycophenolate mofetil (MMF), is widely used in lupus nephritis treatment. Therapeutic drug monitoring of adults suggests that area under the concentration-time curve (AUC) of MPA (MPA-AUC) is associated with clinical outcomes, but childhood data are scarce. METHODS: Retrospective study of 27 children with biopsy-proven lupus nephritis treated with MMF between 2008 and 2016. In 25 children, MPA-AUC was performed within 6 months after kidney biopsy and MMF initiation. Treatment response at 6 months was defined as normal or improved GFR by 25% compared with baseline, 50% reduction of proteinuria to < 0.5 g/day or 50 mg/mmol, and no hematuria. RESULTS: A total of 62 MPA-AUC were analyzed in 27 patients. Overall median was 44 mg h/L (interquartile range [IQR] 33-54). Individual dose adaptation was required in 32 cases (52%) to achieve target AUC of 30-60 mg h/L. At 6 months, 14/25 patients were defined as responders (56%, median MPA-AUC 49 mg h/L (40-59)) and 11/25 as non-responders (44%, 29 mg h/L (24-38)). Patients with MPA-AUC levels > 45, 30-45, and < 30 mg h/L had 6-month response rates of 89% (8/9), 60% (6/10), and 0% (0/6), respectively. In a logistic regression model adjusted for age, sex, lupus nephritis classification, and time since MMF initiation, an MPA-AUC > 45 mg h/L was significantly associated with therapeutic response (OR 3.6, 95% CI 2.4-9.5, p = 0.03). CONCLUSIONS: Therapeutic drug monitoring leading to individualized dosing may improve efficacy of MMF. MPA-AUC > 45 mg h/L is associated with better response rate and may be considered as a target value in pediatric lupus nephritis.

Association of kidney biopsy findings with short- and medium-term outcomes in children with moderate-to-severe IgA vasculitis nephritis.

Assessing the initial severity of immunoglobulin A vasculitis nephritis (IgAV-N) is important due to its determining effect on kidney management and outcomes. This paper describes a multicentre paediatric cohort of IgAV-N patients and discusses relationships among clinical presentation, histological features, and kidney outcome. We retrospectively studied a cohort of 170 children with biopsy-proven IgAV-N, diagnosed between 2007 and 2017. One-quarter of the cohort (27%) presented with initial nephrotic syndrome (NS). Kidney biopsy revealed International Study of Kidney Disease (ISKDC) grade II or grade III in 83% of cases. Endocapillary proliferation was observed in 73% of patients, and chronic lesions were observed in 25%. Data analysis showed a significant association between NS at onset and endocapillary proliferation and cellular crescents. After a median follow-up of 21 months (IQR 12-39), 30% of patients had persistent proteinuria or decreased eGFR. At the end of follow-up, kidney impairment was more often observed in patients with NS at onset and those with cellular crescents and chronic lesions on initial kidney biopsy.Conclusion: This study highlights the relationship between the clinical and histological presentation of IgAV-N and the factors that affect kidney outcome. The ISKDC classification may be improved by including lesions that are more discriminating for disease severity and prognosis. What is Known: • Nephrotic syndrome (NS) or kidney failure at diagnosis and cellular crescents in more than 50% of the glomeruli are recognized as risk factors for poor kidney outcome in immunoglobulin A vasculitis nephritis (IgAV-N). • The reference histological classification of the International Study of Kidney Disease in Children (ISKDC) is primarily based on the presence and number of affected glomeruli (mesangial proliferation, cellular crescents). The updated Oxford classification, which emphasizes tubular atrophy and interstitial fibrosis, is also used to group pathological features of IgAV-N. Both classifications have limitations. What is New: • Medical treatment should not be postponed in patients with IgAV-N and NS until after biopsy, as NS at diagnosis is associated with initial histological severity and poorer kidney outcome. This proposal needs to be verified in further studies. • Endocapillary proliferation is associated with the initial severity of IgAV-N at diagnosis, while chronic glomerular changes and interstitial fibrosis are associated with poorer short- and medium-term kidney outcomes.

An international cohort study of autosomal dominant tubulointerstitial kidney disease due to REN mutations identifies distinct clinical subtypes.

There have been few clinical or scientific reports of autosomal dominant tubulointerstitial kidney disease due to REN mutations (ADTKD-REN), limiting characterization. To further study this, we formed an international cohort characterizing 111 individuals from 30 families with both clinical and laboratory findings. Sixty-nine individuals had a REN mutation in the signal peptide region (signal group), 27 in the prosegment (prosegment group), and 15 in the mature renin peptide (mature group). Signal group patients were most severely affected, presenting at a mean age of 19.7 years, with the prosegment group presenting at 22.4 years, and the mature group at 37 years. Anemia was present in childhood in 91% in the signal group, 69% prosegment, and none of the mature group. REN signal peptide mutations reduced hydrophobicity of the signal peptide, which is necessary for recognition and translocation across the endoplasmic reticulum, leading to aberrant delivery of preprorenin into the cytoplasm. REN mutations in the prosegment led to deposition of prorenin and renin in the endoplasmic reticulum-Golgi intermediate compartment and decreased prorenin secretion. Mutations in mature renin led to deposition of the mutant prorenin in the endoplasmic reticulum, similar to patients with ADTKD-UMOD, with a rate of progression to end stage kidney disease (63.6 years) that was significantly slower vs. the signal (53.1 years) and prosegment groups (50.8 years) (significant hazard ratio 0.367). Thus, clinical and laboratory studies revealed subtypes of ADTKD-REN that are pathophysiologically, diagnostically, and clinically distinct.

The low affinity p75 neurotrophin receptor is down-regulated in congenital anomalies of the kidney and the urinary tract: Possible involvement in early nephrogenesis.

Congenital Anomalies of the Kidney and of the Urinary Tract (CAKUT) cover a broad range of disorders including abnormal kidney development caused by defective nephrogenesis. Here we explored the possible involvement of the low affinity p75 neurotrophin receptor (p75NTR) in CAKUT and nephrogenesis. In mouse, p75NTR was highly expressed in fetal kidney, located within cortical early nephrogenic bodies, and decreased rapidly after birth. In human control fetal kidney, p75NTR was also located within the early nephrogenic bodies as well as in the mature glomeruli, presumably in the mesangium. In CAKUT fetal kidneys, the kidney cortical structure and the localization of p75NTR were often disorganized, and quantification of p75NTR in amniotic fluid revealed a significant reduction in CAKUT compared to control. Finally, invalidation of p75NTR in zebrafish embryo with an antisense morpholino significantly altered pronephros development. Our results indicate that renal p75NTR is altered in CAKUT fetuses, and could participate to early nephrogenesis.

Treatment and long-term outcome in primary nephrogenic diabetes insipidus.

BACKGROUND: Primary nephrogenic diabetes insipidus (NDI) is a rare disorder and little is known about treatment practices and long-term outcome. METHODS: Paediatric and adult nephrologists contacted through European professional organizations entered data in an online form. RESULTS: Data were collected on 315 patients (22 countries, male 84%, adults 35%). Mutation testing had been performed in 270 (86%); pathogenic variants were identified in 258 (96%). The median (range) age at diagnosis was 0.6 (0.0-60) years and at last follow-up 14.0 (0.1-70) years. In adults, height was normal with a mean (standard deviation) score of -0.39 (±1.0), yet there was increased prevalence of obesity (body mass index >30 kg/m2; 41% versus 16% European average; P < 0.001). There was also increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (32%) and adults (48%). Evidence of flow uropathy was present in 38%. A higher proportion of children than adults (85% versus 54%; P < 0.001) received medications to reduce urine output. Patients ≥25 years were less likely to have a university degree than the European average (21% versus 35%; P = 0.003) but full-time employment was similar. Mental health problems, predominantly attention-deficit hyperactivity disorder (16%), were reported in 36% of patients. CONCLUSION: This large NDI cohort shows an overall favourable outcome with normal adult height and only mild to moderate CKD in most. Yet, while full-time employment was similar to the European average, educational achievement was lower, and more than half had urological and/or mental health problems.

Immunoglobulin serum levels in rituximab-treated patients with steroid-dependent nephrotic syndrome.

BACKGROUND: Rituximab (RTX) is efficient in steroid-dependent nephrotic syndrome (SDNS) in pediatric and adult patients. The aim of this study is to describe hypogammaglobulinemia as a side effect of RTX treatment. METHODS: All pediatric patients (< 18 years old) of four French pediatric nephrology centers who received RTX for SDNS between 2010 and 2015 have been included. Clinical and biological data have been analyzed retrospectively before, during, and after RTX treatment. Hypogammaglobulinemia was defined as an IgG level < - 2 standard deviations for patient age. RESULTS: A total of 107 pediatric patients have been included, 65.9% were boys, median age at nephrotic syndrome diagnosis was 3.1 interquartile range [IQ 2.24-5.45] years and age at RTX introduction was 11.7 [IQ 8.6-14.2] years. Twenty-one patients had hypogammaglobulinemia before the initiation of RTX. Of the patients, 25/86 had at least one hypogammaglobulinemia during B cell depletion or after B cell recovery while IgG levels at initiation were normal with a persisting hypogammaglobulinemia for 13 patients 1 year after B cell recovery. Patients who developed hypogammaglobulinemia were younger at RTX initiation with a median age of 8.2 years [IQ 6.3-12.4]. Among all the 46 patients with hypogammaglobulinemia during follow-up, 13 had a concomitant infection. CONCLUSIONS: Hypogammaglobulinemia is a frequent complication of RTX treatment in younger children treated for SDNS. The use of RTX in children has to be carefully evaluated and their clinical and biological follow-up should be adapted to the age-dependent risk profile for hypogammaglobulinemia.

Ofatumumab treatment for nephrotic syndrome recurrence after pediatric renal transplantation.

BACKGROUND: Relapsing nephrotic syndrome (NS) after transplantation can be a challenge to treat. The result of the consequent long-lasting proteinuria is the loss of the graft. Disease recurrence after renal transplantation occurs in around half of cases, and the efficacy of therapeutic strategies is often limited. Recently, ofatumumab, a second-generation and fully human anti-CD20 monoclonal antibody, has been shown to be effective in severe situations. METHODS: We retrospectively collected data from the medical records of children with recurrence of NS after renal transplantation treated with ofatumumab in France, after failure of previous treatments. RESULTS: Six patients were included in this study in five centers with a median duration of follow-up of 10.5 months. Two different ofatumumab regimens were administered. The primary outcome was proteinuria at 6 months after the last dose of ofatumumab. No patient achieved a complete remission, 3/6 had a partial remission, and 3/6 had no response to ofatumumab. Four patients exhibited a minor allergic reaction with the first infusion. One patient died of infection, as a consequence of multiple factors. No malignancies were observed; however, the time of follow-up was not sufficient to see such disease. CONCLUSIONS: Altogether, these results suggest ofatumumab has a poor efficacy in treating recurrence of NS after renal transplantation. However, it could be discussed in multidrug-resistant refractory NS, but infectious complications and overimmunosuppression have to be balanced. There is a need for further studies to confirm these findings and safety and to determine a standardized protocol in this indication.

A single-center study to evaluate the efficacy of a fetal urine peptide signature predicting postnatal renal outcome in fetuses with posterior urethral valves.

BACKGROUND: Posterior urethral valves (PUVs) account for 17% of pediatric renal failure. The management of pregnancies involving fetuses with PUV is hampered by the fact that current clinical parameters obtained from fetal ultrasound and/or fetal urine biochemistry are insufficient to predict postnatal renal function. We previously have developed a fetal urine peptide signature (12PUV) that predicted with high precision postnatal renal failure at 2 years of age in fetuses with PUV. Here, we evaluated the accuracy of this signature to predict postnatal renal outcome in fetuses with PUV in an independent single-center study. METHODS: Thirty-three women carrying fetuses with suspected PUV were included. Twenty-five fetuses received vesicoamniotic shunts during pregnancy. PUV was confirmed postnatally in 23 patients. Of those 23 fetuses, 2 were lost in follow-up. Four and 3 patients died in the pre- and perinatal periods, respectively. Follow-up renal function at 6 months of age was obtained for the remaining 14 patients. The primary outcome was early renal failure, defined by an eGFR < 60 mL/min/1.73 m2 before 6 months of age or pre- or perinatal death. RESULTS: The peptide signature predicted postnatal renal outcome in postnatally confirmed PUV fetuses with an AUC of 0.94 (95%CI 0.74-1.0) and an accuracy of 90% (95%CI 78-100). The signature predicted postnatal renal outcome for the suspected PUV cases with an AUC of 0.89 (95%CI 0.72-0.97) and an accuracy of 84% (95%CI 71-97). CONCLUSIONS: This single-center study confirms the predictive power of the previously identified 12PUV fetal urinary peptide signature.

Social deprivation is associated with poor kidney transplantation outcome in children.

Socioeconomic status is an important determinant of health. Its impact on kidney transplantation outcome has been studied among adults but data in children are scarce, especially in Europe. Here, we investigate the association between the level of social deprivation (determined by the continuous score European Deprivation Index) and graft failure risk in pediatric kidney transplant recipients. All patients listed under 18 years of age who received a first kidney transplant between 2002 and 2014 in France were included. Of 1050 kidney transplant recipients (males 59%, median age at transplantation 13.2 years, preemptive transplantation 23%), 211 graft failures occurred within a median followup of 5.9 years. Thirty-seven percent of these patients belong to the most deprived quintile, suggesting that deprivation is more frequent in pediatric patients with end-stage kidney disease (ESKD) than in the general population. Five- and ten-year graft survival were 85% and 69%, respectively, in the most deprived quintile vs. 90% and 83%, respectively, in the least deprived quintile. At any time after transplantation, patients in the most deprived quintile had almost a two-fold higher hazard of graft failure compared with the least deprived quintile, after adjustment for age at renal replacement therapy, duration of dialysis, primary kidney disease, and rural/urban living environment (hazard ratio 1.99; 95% confidence interval 1.20-3.28). The hazard of graft failure did not differ significantly between girls and boys. Thus, our findings suggest a lower socioeconomic status is independently associated with poor graft outcome in pediatric kidney transplantation.