Fetal bladder morphology as a predictor of outcome in fetal lower urinary tract obstruction

OBJECTIVE

We evaluate survival of fetuses with severe Lower Urinary Tract Obstruction (LUTO) based on bladder morphology. We hypothesize that fetuses with a "floppy" appearing bladder on initial prenatal ultrasound will have worse infant outcomes than fetuses with full/rounded bladders.

METHOD

We retrospectively reviewed all cases of LUTO evaluated in our fetal center between January 2013 and December 2021. Ultrasonographic assessment, renal biochemistry, and bladder refilling contributed to a "favorable" or "unfavorable" evaluation. Bladder morphology on initial ultrasound was classified as "floppy" or "full/rounded." Vesicoamniotic shunting was offered for favorably evaluated fetuses. Baseline demographics, ultrasound parameters, prenatal evaluations of fetal renal function, and infant outcomes were collected. Fetuses diagnosed with severe LUTO were included in analysis using descriptive statistics. The primary outcome measured was survival at 6 months of life.

RESULTS

104 LUTO patients were evaluated; 24 were included in analysis. Infant survival rate at 6 months was 60% for rounded bladders and 0% for floppy bladders (p = 0.003). Bladder refill adequacy was lower in fetuses with floppy bladders compared with rounded bladders (p value < 0.00001).

CONCLUSION

We propose that bladder morphology in fetuses with severe LUTO may be a prognostication factor for predicting infant outcomes and provides a valuable, noninvasive assessment tool.

Utility of kidney ultrasonography during initial evaluation of pediatric nephrotic syndrome

BACKGROUND

Current guidelines note a gap in high-quality evidence regarding utility of kidney ultrasonography (KUS) during initial evaluation of nephrotic syndrome (NS) due to presumed minimal change disease (pMCD). However, KUS is frequently obtained at our institution. This retrospective chart review assessed incidence and impact of abnormal sonographic findings in these patients.

METHODS

Patients 1-18 years, newly diagnosed at our institution with NS from pMCD between 2011 and 2021, were identified. Hypertension, urinalysis, kidney function, and steroid responsiveness data were collected. Imaging findings were abstracted from radiology reports. Clinical impact of KUS was defined by actions taken in response to KUS.

RESULTS

A total of 173 patients identified with new NS; 98 met inclusion criteria. Of these, 54% had KUS during the initial encounter. Demographic and laboratory data did not differ between those with and without KUS. KUS were abnormal in 70% of studies: increased kidney echogenicity (39.6%) and nephromegaly (35.8%) were the most common abnormal findings. Other findings included decreased corticomedullary differentiation, lobular kidney contour, solitary simple kidney cyst, and mild unilateral hydronephrosis. Steroid resistance was not associated with either nephromegaly or abnormal echogenicity.

CONCLUSIONS

Our data showed no clinically relevant ultrasound findings causing deviations from the standard of care for pMCD. There was no association between KUS findings and steroid resistance. These data suggest there is little to no benefit from routine KUS imaging in patients with pMCD upon initial presentation. A higher resolution version of the Graphical abstract is available as Supplementary information.

Polygenic genetic variation affecting antibody formation underlies hypertensive renal injury in the stroke-prone spontaneously hypertensive rat

During development of the spontaneously hypertensive rat (SHR), several distinct but closely related lines were generated. Most lines are resistant to hypertensive renal disease. However, the SHR-A3 line (stroke-prone SHR) experiences end-organ injury (EOI) and provides a model of injury susceptibility that can be used to uncover genetic causation. In the present study, we generated a congenic line in which three distinct disease loci in SHR-A3 are concurrently replaced with homologous loci from an injury-resistant SHR line (SHR-B2). Verification that all three loci were homozygously replaced in this triple congenic line [SHR-A3(Trip B2)] while the genetic background of SHR-A3 was fully retained was obtained by whole genome sequencing. Congenic genome substitution was without effect on systolic blood pressure [198.9 ± 3.34 mmHg, mean ± SE, SHR-A3(Trip B2) = 194.7 ± 2.55 mmHg]. Measures of renal injury (albuminuria, histological injury scores, and urinary biomarker levels) were reduced in SHR-A3(Trip B2) animals, even though only 4.5 Mbases of the 2.8 Gbases of the SHR-B2 genome (0.16% of the genome) was transferred into the congenic line. The gene content of the three congenic loci and the functional effects of gene polymorphism within suggest a role of immunoglobulin in EOI pathogenesis. To prove the role of antibodies in EOI in SHR-A3, we generated an SHR-A3 line in which expression from the immunoglobulin heavy chain gene was knocked out (SHR-A3-IGHKO). Animals in the SHR-A3-IGHKO line lack B cells and immunoglobulin, but the hypertensive phenotype is not affected. Renal injury, however, was reduced in this line, confirming a pathogenic role for immunoglobulin in hypertensive EOI in this model of heritable risk.NEW & NOTEWORTHY Here, we used a polygenic animal model of hypertensive renal disease to show that genetic variation affecting antibody formation underlies hypertensive renal disease. We proved the genetic thesis by generating an immunoglobulin knockout in the susceptible animal model.

Fetal Nephrology: A Quaternary Care Center Experience

Key Points

Specialized fetal centers see a highly complex subset of patients with CAKUT with a predominance of complex or syndromic disease. The mortality rate for fetuses with complex developmental anomalies and CAKUTs or bilateral CAKUTs is high. Prenatal genetic testing was highly variable with limited diagnostic utility while focused postnatal genetic testing had much higher yield.

Background

Congenital anomalies of the kidney and urinary tract (CAKUTs) represent 15%–20% of prenatally diagnosed abnormalities. Maternal characteristics, the frequency of various forms of kidney disease including CAKUT referred for prenatal nephrology consultation, and their perinatal outcomes are less well defined.

Methods

A retrospective chart review was performed of fetal CAKUT and other forms of kidney disease referred for prenatal nephrology consults at Texas Children's Hospital Fetal Center from January 1, 2012, to December 31, 2018.

Results

Two hundred seventeen prenatal nephrology consultations were performed during the study period, representing 4.7% of total Fetal Center referrals at a mean estimated gestational age of 25.2±5.7 weeks. Maternal characteristics were as follows: The mean age was 29.3±5.6 years; 14% had advanced maternal age; 10% had a family history of CAKUT or ESKD; 5% had diabetes mellitus; and 5% of pregnancies were in vitro fertilization-assisted. Fetal characteristics were as follows: 62.7% of fetuses were male and 16% had CAKUT associated with multiple congenital anomalies. The most common prenatal diagnoses were lower urinary tract obstruction in 71 (32.7%), unilateral renal agenesis or multicystic dysplastic kidney (MCDK) in 52 (24.9%), bilateral agenesis or MCDK in 22 (10.1%), and bilateral cystic kidney disease in 19 (8.8%). Seventy-six percent of patients received genetic counseling. One hundred forty-one (64.9%) patients had some form of prenatal genetic testing with a positivity rate of 5.7%. Postnatal characteristics were as follows: 61 (28.1%) patients were seen in prenatal consultation only and no follow-up was available. Of the remaining 156 pregnancies, 136 (86.3%) were viable and delivered at a mean gestational age of 35.2±3.8 weeks. Of these, 100 (64%) survived to discharge. Additional postnatal genetic testing was obtained in 27 infants with a positivity rate of 59%.

Conclusions

Overall perinatal mortality for this cohort as a whole was high (35.8%). While prenatal genetic testing had a limited diagnostic utility, targeted postnatal genetic testing had a much higher diagnostic yield.

Variants in genes coding for collagen type IV α-chains are frequent causes of persistent, isolated hematuria during childhood

BACKGROUND

Children with persistent, isolated microscopic hematuria typically undergo a limited diagnostic workup and are monitored for signs of kidney disease in long-term longitudinal follow-up, which can delay diagnosis and allow disease progression in some cases.

METHODS

To determine the clinical utility of genetic screening in this population, we performed targeted genetic testing using a custom, 32-gene next-generation sequencing panel for progressive kidney disease on children referred to the Texas Children's Hospital Pediatric Nephrology clinic for persistent, microscopic hematuria (n = 30; cohort 1). Patients with microscopic hematuria identified by urinalysis on at least two separate occasions were eligible for enrollment, but those with other evidence of kidney disease were excluded. Results were analyzed for sequence variants using the American College of Medical Genetics and Genomics (ACMG) guideline for data interpretation and were validated using a secondary analysis of a dataset of children with hematuria and normal kidney function who had undergone genetic testing as part of an industry-sponsored program (cohort 2; n = 67).

RESULTS

In cohort 1 33% of subjects (10/30) had pathogenic or likely pathogenic (P/LP) variants in the type IV collagen genes (COL4A3/A4/A5), and 10% (3/30) had variants of uncertain significance in these genes. The high diagnostic rate in type IV collagen genes was confirmed in cohort 2, where 27% (18/67) of subjects had P/LP variants in COL4A3/A4/A5 genes.

CONCLUSIONS

Children with persistent, isolated microscopic hematuria have a high likelihood of having pathogenic variants in type IV collagen genes and genetic screening should be considered. A higher resolution version of the Graphical abstract is available as Supplementary information.

Compound heterozygosity of a de novo submicroscopic deletion and an inherited frameshift pathogenic variant in the PKHD1 gene in a fetus with bilaterally enlarged and echogenic kidneys, enlarged abdomen and oligohydramnios

We present a fetus with bilaterally enlarged and echogenic kidneys. Prenatal testing detected compound heterozygosity for a 0.676 Mb de novo deletion and an inherited pathogenic variant in PKHD1. This is the first case of autosomal recessive polycystic kidney disease (ARPKD) with a prenatally detected disease-causing PKHD1 deletion.

Genetic diagnosis and renal biopsy findings in the setting of a renal genetics clinic

As genetic testing becomes more available, its utilization as an early diagnostic tool in nephrology is more common. The objective of the study is to examine diagnostic agreement between the renal biopsy findings and genetic diagnoses. A retrospective study was conducted in February 2022. A total of 28 patients had both genetic diagnosis and histologic results (n = 1 nephrectomy, n = 27 biopsy). We collected clinical, renal biopsy findings, and genetic information. The relationship between the histologic findings and the genetic diagnoses was classified as: concordant, nonspecific, and discordant. A total of 15 males and 13 females were included (mean age = 9.6 years). Clinical suspicion of Alport syndrome was the most common reason for referral (n = 11, 39.3%), followed by nephrotic syndrome (n = 8, 28.5%), "other" (n = 6, 21.4%), cystic kidney disease (n = 1, 3.6%), isolated hematuria (n = 1, 3.6%), and non-nephrotic proteinuria (n = 1, 3.6%). The overall concordance rate between renal histologic and genetic diagnoses was 71.4% (20/28), nonspecific biopsy results were observed in 17.9% (5/28), and discordant results were observed in 10.7% (3/28). All patients referred for suspected Alport Syndrome had pathogenic/likely pathogenic variants in one of the COL4A genes. Two cases of Lowe syndrome and one of PAX2-associated nephropathy had discordant histology findings. Agreement between renal histologic findings and genetic results varies based on the reason for referral. There was a complete agreement for patients referred for Alport Syndrome; However, there were examples that renal biopsy showed secondary findings that were not specifically associated with the underlying genetic results.

Lupus Nephritis, Autoantibody Production and Kidney Outcomes in Males with Childhood-Onset Systemic Lupus Erythematosus

Childhood-onset systemic lupus erythematosus (cSLE) only represents 20% of all SLE patients, and males with SLE only represent 10%. To study this rare SLE subset, males diagnosed with cSLE over a 30-year period were identified. Organ involvement, autoantibody production, hypocomplementemia, and kidney biopsy findings were compared to cSLE females. Outcomes were assessed using SLE Disease Activity Index scores, Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index, and Childhood Arthritis and Rheumatology Research Alliance definitions for nephritis responsiveness. Of 95 males and 545 females with cSLE, 62% and 57% developed nephritis, respectively. Median age of cSLE onset was 14 years in both genders. Among males, 80% of non-Hispanic whites, 64% of blacks, 59% of Hispanics, and 50% of Asians developed nephritis. The prevalence of pure and mixed class V membranous nephritis was 33%. Median follow-up was 3.2 years (range 0.1-18). Complete kidney responses were seen in 70% after a median 24 months; however, relapse rates were 46%. Kidney disease flares were 56% nephritic and 44% proteinuric. Males and females with cSLE present with comparable rates and nephritis class. While overall and kidney response rates are favorable, kidney disease relapses are common among males.

The effect of continuous venovenous hemodiafiltration on amino acid delivery, clearance, and removal in children

BACKGROUND

In critically ill children with acute kidney injury (AKI), continuous kidney replacement therapy (CKRT) enables nutrition provision. The magnitude of amino acid loss during continuous venovenous hemodiafiltration (CVVHDF) is unknown and needs accurate quantification. We investigated the mass removal and clearance of amino acids in pediatric CVVHDF.

METHODS

This is a prospective observational cohort study of patients receiving CVVHDF from August 2014 to January 2016 in the pediatric intensive care unit (PICU) of a tertiary children's hospital.

RESULTS

Fifteen patients (40% male, median age 2.0 (IQR 0.7, 8.0) years) were enrolled. Median PICU and hospital lengths of stay were 20 (9, 59) and 36 (22, 132) days, respectively. Overall survival to discharge was 66.7%. Median daily protein prescription was 2.00 (1.25, 2.80) g/kg/day. Median daily amino acid mass removal was 299.0 (174.9, 452.0) mg/kg body weight, and median daily amino acid mass clearance was 18.2 (13.5, 27.9) ml/min/m², resulting in a median 14.6 (8.3, 26.7) % protein loss. The rate of amino acid loss increased with increasing dialysis dose and blood flow rate.

CONCLUSION

CVVHDF prescription and related amino acid loss impact nutrition provision, with 14.6% of the prescribed protein removed. Current recommendations for protein provision for children requiring CVVHDF should be adjusted to compensate for circuit-related loss. A higher resolution version of the Graphical abstract is available as Supplementary information.

Emerging Insights Into Chronic Renal Disease Pathogenesis in Hypertension From Human and Animal Genomic Studies

The pathogenic links between elevated blood pressure and chronic kidney disease remain obscure. This article examines progress in population genetics and in animal models of hypertension and chronic kidney disease. It also provides a critique of the application of genome-wide association studies to understanding the heritability of renal function. Emerging themes identified indicate that heritable risk of chronic kidney disease in hypertension can arise from genetic variation in (1) glomerular and tubular protein handling mechanisms; (2) autoregulatory capacity of the renal vasculature; and (3) innate and adaptive immune mechanisms. Increased prevalence of hypertension-associated chronic kidney disease that occurs with aging may reflect amplification of heritable risks by normal aging processes affecting immunity and autoregulation.

Novel scoring system for determining fetal candidacy for prenatal intervention for severe congenital lower urinary tract obstruction

OBJECTIVES

To evaluate a novel scoring system that combines several prenatal parameters for selecting ideal candidates for fetal intervention, and for predicting postnatal survival in patients with severe fetal lower urinary tract obstruction (LUTO).

METHODS

We retrospectively reviewed all cases of severe LUTO evaluated for fetal intervention in a single large fetal center between January 2013 and December 2017. A scoring system for determining fetal candidacy for intervention was retrospectively developed based on postnatal outcomes. The proposed scoring system included fetal urinary biochemistry, renal ultrasound parameters, initial bladder volume, and degree of bladder refill. Relevant demographic characteristics, ultrasound reports and laboratory results were reviewed. Receiver operating characteristic (ROC) curves were used to select the cut-off values for initial bladder volume and degree of bladder refill and to evaluate the performance of the scoring system in predicting postnatal death.

RESULTS

Of the 79 LUTO patients evaluated, 31 were eligible for the study. The overall 6-month postnatal survival was 64.5 % (20/31). A scoring system (0-8) was suggested with 2 points for unfavorable biochemistry, 4 points for ultrasound evidence of dysplastic kidneys, 1 point for inadequate initial bladder volume and 1 point for inadequate bladder refill. Scores>3 (N = 7) were associated with 0 % 6-month survival. The ROC curve for predicting postnatal mortality showed area under curve (AUC) of 0.82 (95 % CI 0.65-0.99). Subgroup analysis within subjects who underwent fetal intervention (N = 22) also confirmed the significance of the distribution of the scoring system between groups who survived and those who did not after adjustment for GA at delivery (p = 0.01).

CONCLUSION

We propose a novel scoring system for antenatal evaluation of patients with severe LUTO which may be useful in selecting those candidates most appropriate for intervention and in counseling parents about predicted postnatal outcome.

Clinical Utility of Genetic Testing in the Precision Diagnosis and Management of Pediatric Patients with Kidney and Urinary Tract Diseases

Background

As genetic testing increasingly integrates into the practice of nephrology, our understanding of the basis of many kidney disorders has exponentially increased. Given this, we recently initiated a Renal Genetics Clinic (RGC) at our large, urban children's hospital for patients with kidney disorders.

Methods

Genetic testing was performed in Clinical Laboratory Improvement Amendments-certified laboratories using single gene testing, multigene panels, chromosomal microarray, or exome sequencing.

Results

A total of 192 patients were evaluated in this clinic, with cystic kidney disease (49/192) being the most common reason for referral, followed by congenital anomalies of the kidney and urinary tract (41/192) and hematuria (38/192). Genetic testing was performed for 158 patients, with an overall diagnostic yield of 81 out of 158 (51%). In the 16 out of 81 (20%) of patients who reached a genetic diagnosis, medical or surgical treatment of the patients were affected, and previous clinical diagnoses were changed to more accurate genetic diagnoses in 12 of 81 (15%) patients.

Conclusions

Our genetic testing provided an accurate diagnosis for children and, in some cases, led to further diagnoses in seemingly asymptomatic family members and changes to overall medical management. Genetic testing, as facilitated by such a specialized clinical setting, thus appears to have clear utility in the diagnosis and counseling of patients with a wide range of kidney manifestations.

Persistent Disease Activity in Patients With Long-Standing Glomerular Disease

Introduction

Methods

Results

Conclusion

Natural genetic variation in Stim1 creates stroke in the spontaneously hypertensive rat

Similar to humans, the risk of cerebrovascular disease in stroke-prone spontaneously hypertensive rats (SHR-A3/SHRSP) arises from naturally occurring genetic variation. In the present study, we show the involvement of genetic variation affecting the store-operated calcium signaling gene, Stim1, in the pathogenesis of stroke in SHR. Stim1 is a key lymphocyte activation signaling molecule and contains functional variation in SHR-A3 that diverges from stroke-resistant SHR-B2. We created a SHR-A3 congenic line in which Stim1 was substituted with the corresponding genomic segment from SHR-B2. Compared with SHR-A3 rats, Stim1 congenic SHR-A3 (SHR-A3(Stim1-B2)) have reduced cerebrovascular disease in response to salt loading including lower neurological deficit scores and cerebral edema. Microbleeds and major hemorrhages occurred in over half of SHR-A3 rats. These lesions were absent in SHR-A3(Stim1-B2) rats. Loss of Stim1 function in mice and humans is associated with antibody-mediated autoimmunity due to defects in T lymphocyte helper function to B cells. We investigated autoantibody formation using a high-density protein array to detect the presence of IgG and IgM autoantibodies in SHR-A3. Autoantibodies to key cerebrovascular stress proteins were detected that were reduced in the congenic line.

Stim1 Polymorphism Disrupts Immune Signaling and Creates Renal Injury in Hypertension

Background

Spontaneously hypertensive rats of the stroke‐prone line (SHR‐A3) develop hypertensive renal disease as a result of naturally occurring genetic variation. Our prior work identified a single‐nucleotide polymorphism unique to SHR‐A3 that results in truncation of the carboxy terminus of STIM1. The SHR‐B2 line, which is also hypertensive but resists hypertensive renal injury, expresses the wild‐type STIM1. STIM1 plays a central role in lymphocyte calcium signaling that directs immune effector responses. Here we show that major defects in lymphocyte function affecting calcium signaling, nuclear factor of activated T cells activation, cytokine production, proliferation, apoptosis, and regulatory T‐cell development are present in SHR‐A3 and attributable to STIM1.

Methods and Results

To assess the role of Stim1 variation in susceptibility to hypertensive renal injury, we created a Stim1 congenic line, SHR‐A3(Stim1‐B2), and STIM1 function was rescued in SHR‐A3. We found that Stim1 gene rescue restores disturbed lymphocyte function in SHR‐A3. Hypertensive renal injury was compared in SHR‐A3 and the SHR‐A3(Stim1‐B2) congenic line. Histologically assessed renal injury was markedly reduced in SHR‐A3(Stim1‐B2), as were renal injury biomarker levels measured in urine. Stim1 deficiency has been linked to the emergence of antibody‐mediated autoimmunity. Renal glomerular immunoglobulin deposition was greater in SHR‐A3 than SHR‐B2 and was reduced by Stim1 congenic substitution. Serum anti–double‐stranded DNA antibody titers in SHR‐A3 were elevated compared with SHR‐B2 and were reduced in SHR‐A3(Stim1‐B2).

Conclusions

Stim1 deficiency in lymphocyte function originating from Stim1 truncation in SHR‐A3 combines with hypertension to create end organ disease and may do so as a result of antibody formation.

Characterization of the renal phenotype in RMND1-related mitochondrial disease

BACKGROUND

The nuclear encoded gene RMND1 (Required for Meiotic Nuclear Division 1 homolog) has recently been linked to RMND1-related mitochondrial disease (RRMD). This autosomal recessive condition characteristically presents with an infantile-onset multisystem disease characterized by severe hypotonia, global developmental delay, failure to thrive, sensorineural hearing loss, and lactic acidosis. Renal disease, however, appears to be one of the more prominent features of RRMD, affecting patients at significantly higher numbers compared to other mitochondrial diseases. We report the clinical, histological, and molecular findings of four RRMD patients across three academic institutions with a focus on the renal manifestations.

METHODS

Four patients were identified for the purpose of this study, all of whom had molecular confirmation at the time of inclusion, which included the common pathogenic variant c.713A>G (p.N238S) as well as the three rare variants: c.485delC (p.P162fs), c.533C>T (p.T178M), and c.1317 + 1G>C splice donor variant. Medical history and laboratory findings were collected from the medical records and medical providers.

RESULTS

In this study, all four patients developed renal disease characterized as tubulopathy (3/4), renal tubular acidosis (2/4), interstitial nephritis (1/4), and/or end-stage renal disease (4/4) necessitating renal transplantation (2/4). Histological evaluation of renal biopsy specimens revealed generalized tubular atrophy and on electron microscopy, abundant mitochondria with pleomorphism and abnormal cristae.

CONCLUSION

Our experience with RRMD demonstrates a specific pattern of renal disease manifestations and clinical course. Patients are unlikely to respond to traditional chronic kidney disease (CKD) treatments, making early diagnosis and consideration of renal transplantation paramount to the management of RRMD.

DYRK1A-related intellectual disability: a syndrome associated with congenital anomalies of the kidney and urinary tract

PURPOSE

Haploinsufficiency of DYRK1A causes a recognizable clinical syndrome. The goal of this paper is to investigate congenital anomalies of the kidney and urinary tract (CAKUT) and genital defects (GD) in patients with DYRK1A variants.

METHODS

A large database of clinical exome sequencing (ES) was queried for de novo DYRK1A variants and CAKUT/GD phenotypes were characterized. Xenopus laevis (frog) was chosen as a model organism to assess Dyrk1a's role in renal development.

RESULTS

Phenotypic details and variants of 19 patients were compiled after an initial observation that one patient with a de novo pathogenic variant in DYRK1A had GD. CAKUT/GD data were available from 15 patients, 11 of whom presented with CAKUT/GD. Studies in Xenopus embryos demonstrated that knockdown of Dyrk1a, which is expressed in forming nephrons, disrupts the development of segments of embryonic nephrons, which ultimately give rise to the entire genitourinary (GU) tract. These defects could be rescued by coinjecting wild-type human DYRK1A RNA, but not with DYRK1AR205* or DYRK1AL245R RNA.

CONCLUSION

Evidence supports routine GU screening of all individuals with de novo DYRK1A pathogenic variants to ensure optimized clinical management. Collectively, the reported clinical data and loss-of-function studies in Xenopus substantiate a novel role for DYRK1A in GU development.

Germ-line genetic variation in the immunoglobulin heavy chain creates stroke susceptibility in the spontaneously hypertensive rat

The risk of cerebrovascular disease in stroke-prone spontaneously hypertensive rats (SHR-A3/SHRSP) arises from naturally occurring genetic variation. In the present study we show the involvement of SHR genetic variation that affects antibody formation and function in the pathogenesis of stroke. We have tested the involvement in susceptibility to stroke of genetic variation in IgH, the gene encoding the immunoglobulin heavy chain by congenic substitution. This gene contains functional natural variation in SHR-A3 that diverges from stroke-resistant SHR-B2. We created a SHR-A3 congenic line in which the IgH gene was substituted with the corresponding haplotype from SHR-B2. Compared with SHR-A3 rats, congenic substitution of the IgH locus [SHR-A3(IgH-B2)] markedly reduced cerebrovascular disease. Given the role in antibody formation of the IgH gene, we investigated the presence of IgG and IgM autoantibodies and their targets using a high-density protein array containing ~20,000 recombinant proteins. High titers of autoantibodies to key cerebrovascular stress proteins were detected, including FABP4, HSP70, and Wnt signaling proteins. Serum levels of these autoantibodies were reduced in the SHR-A3(IgH-B2) congenic line.

Outcome of fetuses with lower urinary tract obstruction and normal amniotic fluid volume in second trimester of pregnancy

OBJECTIVE

Congenital lower urinary tract obstruction (LUTO) is a rare condition with high perinatal mortality and morbidity when associated with severe oligohydramnios or anhydramnios in the second trimester of pregnancy. Severe pulmonary hypoplasia and end-stage renal disease are the underlying causes of poor neonatal outcome in these cases. However, little is known about the subset of fetal LUTO that is associated with a normal volume of amniotic fluid at midgestation. The objective of the current study was to describe the natural history, underlying causes, survival and postnatal renal function outcomes in pregnancies with fetal LUTO and normal amniotic fluid volume during the second trimester of pregnancy.

METHODS

This was a retrospective study of all pregnancies with fetal LUTO and normal amniotic fluid volume in the second trimester that received prenatal and postnatal care at our quaternary care institution between 2013 and 2017. Data on demographic characteristics, fetal interventions, perinatal survival, need for neonatal respiratory support, postnatal renal function and need for dialysis at the age of 1 and 24 months were analyzed.

RESULTS

Of the 18 fetuses that met the study criteria, 17 (94.4%) survived the perinatal period. Eleven (61.1%) pregnancies developed oligohydramnios in the third trimester, six of which were eligible for and underwent fetal intervention with vesicoamniotic shunt placement, which was performed successfully in all six cases. Two (11.1%) neonates required respiratory support owing to pulmonary hypoplasia. At the age of 2 years, 14 children had follow-up information available, two (14.3%) of whom had normal renal function, eight (57.1%) had developed some degree of chronic kidney disease (Stage 1-4) and four (28.6%) had developed end-stage renal disease (ESRD), including two who had already manifested ESRD in the neonatal period.

CONCLUSIONS

Most fetuses diagnosed prenatally with LUTO that is associated with a normal volume of amniotic fluid at midgestation will have a favorable outcome in terms of perinatal survival and few will need long-term respiratory support. However, these children are still at increased risk for chronic renal disease, ESRD and need for renal replacement therapy. Larger multicenter studies are needed to characterize the prenatal factors associated with postnatal renal function, and to investigate the role of fetal intervention in the group of fetuses that present with late-onset oligohydramnios and evidence of preserved fetal renal function. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Surgical interventions and anesthesia in the 1st year of life for lower urinary tract obstruction

BACKGROUND

Patients with a prenatal diagnosis of lower urinary tract obstruction (LUTO) may undergo prenatal interventions, such as vesicoamniotic shunt (VAS) placement, as a temporary solution for relieving urinary tract obstruction. A recent FDA communication has raised awareness of the potential neurocognitive adverse effects of anesthesia in children. We hypothesized as to whether a prenatal LUTO staging system was predictive of the number of anesthesia events for prenatally diagnosed LUTO patients.

METHODS

We retrospectively reviewed the prenatal and postnatal clinical records for patients with prenatally diagnosed LUTO from 2012 to 2015. Patients were stratified by prenatal VAS status and by LUTO disease severity according to Ruano et al. (Ultrasound Obstet Gynecol. 2016).

RESULTS

31 patients were identified with a prenatal LUTO diagnosis, and postnatal records were available for 21 patients (seven patients in each stage). When combining prenatal and postnatal anesthesia, there was a significant difference in the number of anesthesia encounters by stage (1.6, 3.7, and 6.7 for Stage I, II, and III respectively, p = .034). Upon univariate analysis, higher gestational age (GA) at birth was associated with a decreased number of anesthesia events in the first year (p = .031).

CONCLUSIONS

The majority of infants with prenatally diagnosed LUTO will undergo postnatal procedures with general anesthesia exposure in the first year of life. Patients with higher prenatal LUTO severity experienced a higher number of both prenatal and postnatal anesthesia encounters. In addition, higher GA at birth was associated with fewer anesthesia encounters in the first year.

LEVEL OF EVIDENCE

This is a prognostic study with Level IV evidence.

Peritoneal dialysis catheter outcomes in infants initiating peritoneal dialysis for end-stage renal disease

Background

End-stage renal disease (ESRD) although rare among infants presents many management challenges. We sought to evaluate factors associated with PD catheter failure among infants initiated on chronic PD.

Methods

A retrospective chart review of all children under two years of age who had PD catheters placed for initiation of chronic PD from 2002 to 2015. Data was extracted for catheter related events occurring within 12 months of catheter placement. Cox and Poisson regression models were used to delineate factors associated catheter complications.

Results

Twenty-five infants with median age 18 days had PD catheters placed for chronic dialysis. Common complications included leakage around the exit site (31%), blockage (26%), migration or malposition (23%), catheter-related infections (18%), and other complications (2%). Predictors of initial PD catheter failure were age less than one month at catheter placement (hazard ratio (HR) 7.77, 95% CI, 1.70–35.39, p = 0.008), use of catheter within three days of placement (HR 5.67, 95% CI, 1.39–23.10, p = 0.015) and presence of a hernia (HR 8.64, 95% CI, 1.19–62.36, p = 0.033). In an adjusted Poisson regression model, PD catheter use within three days of placement was the only predictor of any catheter complication over the12 months of follow up.

Conclusions

Use of PD catheters within three days of placement was associated with catheter failure. We recommend that when possible, catheters should be allowed to heal for at least three days prior to use to reduce risk of complications and improve catheter survival.

Abstract 028: Susceptibility to Strokes in Spontaneously Hypertensive Rats Due to a Mutation in Stim1

Stroke-prone spontaneously hypertensive rats (SHR-A3/SHRSP) develop cerebrovascular disease as a result of naturally occurring genetic variation. We recently identified a novel truncating mutation in the SHR-A3 line affecting the C-terminus of STIM1, a protein involved in the store-operated Ca 2+ entry (SOCE) pathway. The SHR-B2 line, which is also hypertensive but resists end organ injury, expresses the ‘wild type’ Stim1 . Here, we test whether the emergence of cerebrovascular disease in SHR-A3 is prevented by gene rescue of Stim1 . We created a Stim1 congenic line (SHR-A3( Stim1 -B2)), in which the functional Stim1 allele was transferred from the SHR-B2 line into the stroke-prone SHR-A3 genome. SHR-A3 and SHR-A3( Stim1 -B2) rats were salt loaded (1% NaCl in drinking water) for 8 weeks starting at 20 weeks of age to induce strokes. Baseline BP measured by telemetry before salt loading was not different between SHR-A3 and SHR-A3( Stim1 -B2) rats (199.5±6.49 vs 196.26±2.431 mmHg, ns). Salt loading resulted in a progressive increase in BP in SHR-A3 rats, but was blunted in SHR-A3( Stim1 -B2) rats. Compared to SHR-A3 rats, Stim1 -rescue congenic rats had improved survival (% survival: 100 (9 of 9) vs 22.2% (2 of 9) at the end of 8 weeks) and lower neurological deficit scores (2.45±0.412 vs 1±0.00, p<0.01). Salt loading resulted in significant cerebral edema in SHR-A3 rats but not in the SHR-A3( Stim1 -B2) rats (% brain wt/body wt: 0.805±0.045 vs 0.617±0.009, p<0.01). Gross morphology of the brain revealed microbleeds and hemorrhages in 5 of 9 SHR-A3 rats. These lesions were absent in SHR-A3( Stim1 -B2) rats. Stim1 gene rescue in the congenic line was also associated with decreased susceptibility to renal injury assessed histologically at 40 weeks of age (glomerular injury: 1.915±0.086 vs 1.355±0.071, p<0.001; tubulointerstitial injury: 3.2±0.102 vs 1.69±0.112, p<0.001). Our findings identify Stim1 as a major candidate gene that promotes susceptibility to strokes as well as renal injury in spontaneously hypertensive rats.

Susceptibility to Hypertensive Renal Disease in the Spontaneously Hypertensive Rat Is Influenced by 2 Loci Affecting Blood Pressure and Immunoglobulin Repertoire

High blood pressure exerts its deleterious effects on health largely through acceleration of end-organ diseases. Among these, progressive loss of renal function is particularly important, not only for the direct consequences of kidney damage but also because loss of renal function is associated with amplification of other adverse cardiovascular outcomes. Genetic susceptibility to hypertension and associated end-organ disease is non-Mendelian in both humans and in a rodent model, the spontaneously hypertensive rat (SHR). Here, we report that hypertensive end-organ disease in the inbred SHR-A3 line is attributable to genetic variation in the immunoglobulin heavy chain on chromosome 6. This variation coexists with variation in a 10 Mb block on chromosome 17 that contains genetic variation in 2 genes involved in immunoglobulin Fc receptor signaling. Substitution of these genomic regions into the SHR-A3 genome from the closely related, but injury-resistant, SHR-B2 line normalizes both biomarker and histological measures of renal injury. Our findings indicate that genetic variation leads to a contribution by immune mechanisms hypertensive end-organ injury and that, in this rat model, disease is influenced by differences in germ line antibody repertoire.

Therapeutic Plasma Exchange Use in Pediatric Neurologic Disorders at a Tertiary Care Center: A 10-Year Review

Pediatric neurologic conditions requiring therapeutic plasma exchange are rare in children and literature is sparse. The study aims to determine the outcomes, safety, and feasibility of therapeutic plasma exchange treatment in pediatric neurologic disorders. This retrospective analysis looked at the outcomes and safety of therapeutic plasma exchange in children (n = 50) with neurologic conditions. Patient age ranged <1 to 19 years old with a mean of 10.35 years. Of the 50 children treated with plasmapheresis, 26 patients received inpatient rehabilitation. At discharge, functional status can be summarized as follows: 24 (48%) with mental status impairment, 10 (20%) with vision impairment, 19 (38%) with bladder incontinence, and 37 (74%) with motor impairment. Three-month follow-up: 30% with mental status impairment, 10% with vision impairment, 18% with bladder incontinence, and 52% with motor impairment. Therapeutic plasma exchange is an effective and safe therapy for neurological conditions in the pediatric population.

Lower urinary tract obstruction: fetal intervention based on prenatal staging

The authors present an overview of lower urinary tract obstruction (LUTO) in the fetus with a particular focus on the insult to the developing renal system. Diagnostic criteria along with the challenges in estimating long-term prognosis are reviewed. A proposed prenatal LUTO disease severity classification to guide management decisions with fetal intervention to maintain or salvage in utero and neonatal pulmonary and renal function is also discussed. Stage I LUTO (mild form) is characterized by normal amniotic fluid index after 18 weeks, normal kidney echogenicity, no renal cortical cysts, no evidence of renal dysplasia, and favorable urinary biochemistries when sampled between 18 and 30 weeks; prenatal surveillance is recommended. Stage II LUTO is characterized by oligohydramnios/anhydramnios, hyperechogenic kidneys but absent renal cortical cysts or apparent signs of renal dysplasia and favorable fetal urinary biochemistry; fetal vesicoamniotic shunting (VAS) or fetal cystoscopy is indicated to prevent pulmonary hypoplasia and renal failure. Stage III LUTO is oligohydramnios/anhydramnios, hyperechogenic kidneys with cortical cysts and renal dysplasia and unfavorable fetal urinary biochemistry after serial evaluation; fetal vesicoamniotic shunt may prevent severe pulmonary hypoplasia but not renal failure. Stage IV is characterized by intrauterine fetal renal failure, defined by anhydramnios and ultrasound (US) findings suggestive of severe renal dysplasia, and is associated with death in 24 h of life or end-stage renal disease (ESRD) within the first week of life; fetal vesicoamniotic shunt and fetal cystoscopy are not indicated.

Regional citrate anticoagulation for continuous renal replacement therapy in pediatric patients with liver failure

Pediatric liver failure patients frequently develop multiple organ failure and require continuous renal replacement therapy (CRRT) as part of supportive therapy in the pediatric intensive care unit. While many centers employ no anticoagulation for fear of bleeding complications, balanced coagulation disturbance predisposes these patients to clotting as well as bleeding, making maintenance of longer circuit life to deliver adequate dialysis clearance challenging. Regional citrate anticoagulation (RCA) is an attractive option as it avoids systemic anticoagulation, but since citrate metabolism is impaired in liver failure, concerns about toxicity has limited its use. Pediatric data on RCA with liver failure is very scarce. We aimed to establish safety and efficacy of RCA in pediatric liver failure patients on CRRT. Retrospective review of pediatric patients with liver failure receiving CRRT over 30 months. Demographic data and CRRT related data were collected by chart review. Citrate accumulation (CA) was defined as total calcium (mg/dl) /ionized calcium (mmol/L) ratio >2.5 for > 48 hours. Efficacy was assessed by filter life. Safety was assessed by frequency of adverse events ((AEs) defined as bleeding, hemodynamic instability, arrhythmias). Fifty-one patients (median age 3.5 (IQR 0.75-14.2) years) received 861 CRRT days; 70% experienced at least one episode of CA, only 37% were recorded as such in the medical record. AE rate was 93/1000 CRRT days and did not differ between CA days and others. Median filter life was 66 hours (IQR 29-74); 63% filters lasted longer than 48 hrs. Though common, CA was not associated with increased AEs on in pediatric liver failure patients on CRRT receiving RCA. Filter life was adequate. RCA appears an effective anticoagulation for CRRT in pediatric liver failure. Application of a structured definition would increase recognition of CA to allow timely intervention.

Report on The Society for Fetal Urology panel discussion on the selection criteria and intervention for fetal bladder outlet obstruction

INTRODUCTION

The Society for Fetal Urology panel section at the 2016 Fall Congress featured a multidisciplinary discussion on appropriate patient selection, the conservative versus surgical management, and postnatal renal outcome of fetuses with lower urinary tract obstruction (LUTO).

SELECTION CRITERIA FOR INTERVENTION

Rodrigo Ruano shared his experience of prenatal intervention, presenting the outcome of 111 fetuses with severe LUTO treated with vesicoamniotic shunting (VAS) (n = 16), cystoscopy (n = 34) or no intervention (n = 61) in a non-randomized series. Multivariate analysis at the 6-month follow-up suggested a significantly higher probability of survival with fetal intervention versus no intervention. A clear trend for normal renal function was present in the fetal cystoscopy group, but not in the VAS group. In cases in which there was a postnatal diagnosis of posterior urethral valves (n = 57), fetal cystoscopy was effective in improving both the 6-month survival rate and renal function, while VAS was associated with an improvement in the 6-month survival rate. In an attempt to better define which fetuses would benefit from intervention, Michael Braun explained the proposed LUTO classification system that incorporates: (1) fetal urinary biomarkers of renal injury; (2) amniotic fluid levels as a surrogate for the severity of obstruction; and (3) imaging studies to identify signs of renal dysplastic or cystic changes. Intervention was not recommended in patients at low risk of either renal disease or pulmonary hypoplasia (Stage 1). Vesicoamniotic shunting was performed in patients at high risk of either progressive renal injury or pulmonary hypoplasia without evidence of severe pre-existing renal damage (Stage 2). For those patients, who at the time of evaluation had evidence of severe renal disease (Stage 3), fetal intervention was individualized and often based on bladder capacity and bladder refilling after vesicocentesis. He went on to present the nephrologic outcome of fetuses managed over the last 3 years utilizing the selection criteria. Craig Peters supported the concept of selective criteria and discussed the cautious viewpoint, namely: (1) the procedure may be unnecessary, as it is possible for patients to do well, in spite of severe prenatal obstruction; and (2) the risk of giving partial treatment by allowing the baby to survive to delivery with the daunting postnatal journey of renal and pulmonary insufficiency.

CONCLUSION

Standardized patient selection utilizing a staging system is undoubtedly the way forward and will enable comparable long-term renal and bladder functional outcome studies.

Hemolytic uremic syndrome as the presenting manifestation of WT1 mutation and Denys-Drash syndrome: a case report

Background

Hemolytic uremic syndrome (HUS) can occur as a primary process due to mutations in complement genes or secondary to another underlying disease. HUS sometimes occurs in the setting of glomerular diseases, and it has been described in association with Denys-Drash syndrome (DDS), which is characterized by the triad of abnormal genitourinary development; a pathognomonic glomerulopathy, diffuse mesangial sclerosis; and the development of Wilms tumor.

Case presentation

We report the case of a 46, XX female infant who presented with HUS and biopsy-proven thrombotic microangiopathy. Next generation sequencing of genes with known mutations causative of atypical HUS found that she was homozygous for the Complement Factor H H3 haplotype and heterozygous for a variant of unknown significance in the DGKE gene. Whole exome sequencing identified a de novo heterozygous WT1 c.1384C > T; p.R394W mutation, which is classically associated with Denys-Drash syndrome (DDS). At the time of bilateral nephrectomy five months after her initial biopsy, she had diffuse mesangial sclerosis, typical of Denys-Drash syndrome, without evidence of thrombotic microangiopathy.

Conclusion

This unique case highlights HUS as a rare but important manifestation of WT1 mutation and provides new insight into the genetics underlying this association.

Mycophenolate mofetil prevents cerebrovascular injury in stroke-prone spontaneously hypertensive rats

Stroke-prone spontaneously hypertensive rats (SHR-A3) develop strokes and progressive kidney disease as a result of naturally occurring genetic variations. We recently identified genetic variants in immune signaling pathways that contribute to end-organ injury. The present study was designed to test the hypothesis that a dysregulated immune response promotes stroke susceptibility. We salt-loaded 20 wk old male SHR-A3 rats and treated them with the immunosuppressant mycophenolate mofetil (MMF, 25 mg/kg/day po) (n = 8) or vehicle (saline) (n = 9) for 8 wk. Blood pressure (BP) was measured weekly by telemetry. Compared with vehicle-treated controls, MMF-treated SHR-A3 rats had improved survival and lower neurological deficit scores (1.44 vs. 0.125; P < 0.02). Gross morphology of the brain revealed cerebral edema in 8 of 9, and microbleeds and hemorrhages in 5 of 9 vehicle-treated rats. These lesions were absent in MMF-treated rats. Brain CD68 expression, indicating macrophage/microglial activation, was upregulated in vehicle-treated rats with microbleeds and hemorrhages but was undetectable in the brains of MMF-treated rats. MMF also prevented renal injury in SHR-A3 rats, evidenced by reduced proteinuria (albumin:creatinine) from 7.52 to 1.05 mg/mg (P < 0.03) and lower tubulointerstitial injury scores (2.46 vs. 1.43; P < 0.01). Salt loading resulted in a progressive increase in BP, which was blunted in rats receiving MMF. Our findings provide evidence that abnormal immune activation predisposes to cerebrovascular and renal injury in stroke-prone SHR-A3 rats.

Fetal lower urinary tract obstruction: proposal for standardized multidisciplinary prenatal management based on disease severity

OBJECTIVE

To present a single center experience of a standardized prenatal multidisciplinary management protocol for fetal lower urinary tract obstruction (LUTO) and to propose a classification of fetal LUTO based on disease severity.

METHODS

This was a retrospective cohort study of 25 consecutive fetal patients with prenatal diagnosis of primary LUTO. Fetal intervention was offered after evaluation by a multidisciplinary team. Analyses were conducted using Bayesian methodology to determine predictors of survival at 6 months postpartum. Odds ratios (ORs) with 95% credibility intervals are reported.

RESULTS

Fifteen (60.0%) of the 25 patients referred for assessment survived to postnatal evaluation. Fetal vesicoamniotic shunt was placed in 14 (56.0%) patients with 12 survivors. Multivariable analysis suggested that fetal intervention (OR, 6.97 (0.88-70.16), Pr(OR > 1) = 96.7%), anhydramnios (OR, 0.12 (0.04-0.35), Pr(OR < 1) = 99.9%), favorable fetal urine analysis (OR, 3.98 (0.63-25.15), Pr(OR > 1) = 92.7%) and absence of renal cortical cysts (OR, 3.9 (0.66-24.2), Pr(OR > 1) = 93.3%) were predictors of survival.

CONCLUSIONS

Fetal intervention and fetal renal function were independently associated with postnatal survival of fetuses with LUTO. A classification based on the severity of disease is proposed. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Factors associated with fetal shunt dislodgement in lower urinary tract obstruction

OBJECTIVE

To identify factors associated with fetal shunt dislodgement in lower urinary tract obstruction (LUTO).

METHODS

We conducted a retrospective study of 42 consecutive fetuses with a diagnosis of LUTO in a tertiary fetal center between April 2013 and November 2015. Possible factors associated with prenatal shunt dislodgment were evaluated in fetuses who underwent shunt placement, including gestational age at diagnosis, gestational age at procedure, presence of 'keyhole sign', initial fetal bladder volume and wall thickness, prenatal ultrasonographic renal characteristics, amniotic fluid volume, presence of ascites prior to shunting, and type of fetal shunt.

RESULTS

Nineteen (46.3%) fetuses underwent shunt placement at a median gestational age of 19 (range: 16.3-31.1) weeks. Shunt dislodgement occurred in 10 (52.6%) patients. A total of 35 procedures were performed; among which 16 (45.7%) were repeat procedures. The only prenatal factor associated with shunt dislodgement was the type of the shunt; Kaplan-Meier analysis indicated that the Rocket was associated with increased likelihood of remaining orthotopic (p = 0.04).

CONCLUSION

Fetal shunt dislodgement occurs in approximately half of the patients and appears to be associated with the type of the shunt. Future research is necessary to develop better shunt systems and to investigate different fetal therapeutic approaches. © 2016 John Wiley & Sons, Ltd.

Copa Syndrome: a Novel Autosomal Dominant Immune Dysregulatory Disease

Inherently defective immunity typically results in either ineffective host defense, immune regulation, or both. As a category of primary immunodeficiency diseases, those that impair immune regulation can lead to autoimmunity and/or autoinflammation. In this review we focus on one of the most recently discovered primary immunodeficiencies that leads to immune dysregulation: "Copa syndrome". Copa syndrome is named for the gene mutated in the disease, which encodes the alpha subunit of the coatomer complex-I that, in aggregate, is devoted to transiting molecular cargo from the Golgi complex to the endoplasmic reticulum (ER). Copa syndrome is autosomal dominant with variable expressivity and results from mutations affecting a narrow amino acid stretch in the COPA gene-encoding COPα protein. Patients with these mutations typically develop arthritis and interstitial lung disease with pulmonary hemorrhage representing a striking feature. Immunologically Copa syndrome is associated with autoantibody development, increased Th17 cells and pro-inflammatory cytokine expression including IL-1β and IL-6. Insights have also been gained into the underlying mechanism of Copa syndrome, which include excessive ER stress owing to the impaired return of proteins from the Golgi, and presumably resulting aberrant cellular autophagy. As such it represents a novel cellular disorder of intracellular trafficking associated with a specific clinical presentation and phenotype.

Defining and predicting 'intrauterine fetal renal failure' in congenital lower urinary tract obstruction

BACKGROUND

The aim of this study was to identify predictors of 'intrauterine fetal renal failure' in fetuses with severe congenital lower urinary tract obstruction (LUTO).

METHODS

We undertook a retrospective study of 31 consecutive fetuses with a diagnosis of LUTO in a tertiary Fetal Center between April 2013 and April 2015. Predictors of 'intrauterine fetal renal failure' were evaluated in those infants with severe LUTO who had either a primary composite outcome measure of neonatal death in the first 24 h of life due to severe pulmonary hypoplasia or a need for renal replacement therapy within 7 days of life. The following variables were analyzed: fetal bladder re-expansion 48 h after vesicocentesis, fetal renal ultrasound characteristics, fetal urinary indices, and amniotic fluid volume.

RESULTS

Of the 31 fetuses included in the study, eight met the criteria for 'intrauterine fetal renal failure'. All of the latter had composite poor postnatal outcomes based on death within 24 h of life (n = 6) or need for dialysis within 1 week of life (n = 2). The percentage of fetal bladder refilling after vesicocentesis at time of initial evaluation was the only predictor of 'intrauterine fetal renal failure' (cut-off <27 %, area under the time-concentration curve 0.86, 95 % confidence interval 0.68-0.99; p = 0.009).

CONCLUSION

We propose the concept of 'intrauterine fetal renal failure' in fetuses with the most severe forms of LUTO. Fetal bladder refilling can be used to reliably predict 'intrauterine fetal renal failure', which is associated with severe pulmonary hypoplasia or the need for dialysis within a few days of life.

Urological fistulas after fetal cystoscopic laser ablation of posterior urethral valves: surgical technical aspects

OBJECTIVE

To describe the surgical technical aspects associated with the development of urological fistulas after fetal antegrade cystoscopic laser fulguration of the posterior urethral valves (PUV).

METHODS

The perioperative data for all fetal cystoscopies performed between January 2004 and August 2013 at three institutions in the USA, France and Brazil were reviewed, with particular emphasis on surgical technical aspects of the procedure and the complications encountered.

RESULTS

A total of 40 fetal cystoscopies were performed at the three institutions. Laser fulguration of the PUV was performed in 23 of these cases, with a survival rate of 60.9% (14/23) and normal renal function in 85.7% (12/14) of these infants. Urological fistulas were diagnosed postnatally in four (10%) newborns. The presence of fistulas was associated with a higher gestational age at diagnosis of PUV (P < 0.01) and with the use of semi-curved rather than curved sheaths (P < 0.01), the use of a diode laser (P < 0.01) and the use of higher laser power and energy (P < 0.01 and P < 0.01, respectively), as well as with less operator experience (P < 0.01) and with absence of fetal anesthesia/immobilization (P = 0.02).

CONCLUSION

Urological fistulas are a severe complication of fetal cystoscopic laser fulguration of PUV and are associated with type, energy and power settings of the laser and instrumentation. The use of appropriate technique and proper training of the operator are necessary to perform this fetal intervention safely.

Hypertensive renal injury is associated with gene variation affecting immune signaling

BACKGROUND

The spontaneously hypertensive rat (SHR) strain exists in lines that contrast strongly in susceptibility to renal injury in hypertension. These inbred lines share common ancestry, and only 13% of their genomes arise from different ancestors.

METHODS AND RESULTS

We used next gen sequencing to detect natural allelic variation in 5 genes of the immunoreceptor signaling pathway (IgH, Dok3, Src, Syk, and JunD) that arise from different ancestors in the injury-prone SHR-A3 and the resistant SHR-B2 lines. We created an intercross between these lines, and in the F2 progeny, we observed that the inheritance of haplotype blocks containing the SHR-A3 alleles of these 5 genes correlated with increased albuminuria and histological measures of renal injury. To test whether accumulated genetic variation in this pathway may create a therapeutic target in hypertensive renal injury, rats of both lines were treated with the immunosuppressant mycophenolate mofetil (MMF). MMF reduced proteinuria (albumin to creatinine ratio) from 6.6 to 1.2 mg/mg (P<0.001) in SHR-A3. Glomerular injury scores were reduced in MMF-treated SHR-A3 from 1.6 to 1.4 (P<0.002). Tubulo-interstitial injury was reduced in MMF-treated SHR-A3 from 2.62 to 2.0 (P=0.001). MMF treatment also reduced renal fibrosis in SHR-A3 (3.9 versus 2.0; P<0.001).

CONCLUSIONS

Polygenic susceptibility to renal injury in hypertension arises in association with genetic variation in genes that participate in immune responses and is dramatically improved by reduction of immune system activity.

Consensus expert recommendations for the diagnosis and management of autosomal recessive polycystic kidney disease: report of an international conference

Autosomal recessive polycystic kidney disease (ARPKD; MIM 263200) is a severe, typically early onset form of cystic disease that primarily involves the kidneys and biliary tract. Phenotypic expression and age at presentation can be quite variable1 . The incidence of ARPKD is 1 in 20,000 live births2 , and its pleotropic manifestations are potentially life-threatening. Optimal care requires proper surveillance to limit morbidity and mortality, knowledgeable approaches to diagnosis and treatment, and informed strategies to optimize quality of life. Clinical management therefore is ideally directed by multidisciplinary care teams consisting of perinatologists, neonatologists, nephrologists, hepatologists, geneticists, and behavioral specialists to coordinate patient care from the perinatal period to adulthood. In May 2013, an international team of 25 multidisciplinary specialists from the US, Canada, Germany, and the United Kingdom convened in Washington, DC, to review the literature published from 1990 to 2013 and to develop recommendations for diagnosis, surveillance, and clinical management. Identification of the gene PKHD1, and the significant advances in perinatal care, imaging, medical management, and behavioral therapies over the past decade, provide the foundational elements to define diagnostic criteria and establish clinical management guidelines as the first steps towards standardizing the clinical care for ARPKD patients. The key issues discussed included recommendations regarding perinatal interventions, diagnostic criteria, genetic testing, management of renal and biliary-associated morbidities, and behavioral assessment. The meeting was funded by the National Institutes of Health and an educational grant from the Polycystic Kidney Disease Foundation. Here we summarize the discussions and provide an updated set of diagnostic, surveillance, and management recommendations for optimizing the pediatric care of patients with ARPKD. Specialist care of ARPKD-related complications including dialysis, transplantation, and management of severe portal hypertension will be addressed in a subsequent report. Given the paucity of information regarding targeted therapies in ARPKD, this topic was not addressed in this conference.”

Diversity in the preimmune immunoglobulin repertoire of SHR lines susceptible and resistant to end-organ injury

We used next-generation sequencing to identify IGH genetic variation in two closely related hypertensive rat lines that differ in susceptibility to end-organ disease (SHR-A3 and SHR-B2). The two SHR lines differ extensively at the IGH locus from the rat reference genome sequence (RRGS) and from each other, creating 306 sequence unique IGH genes. Compared to IGH genes mapped in the RRGS, 98 are null gene alleles (31 are null in both SHR lines, 45 are null in SHR-A3 only, and 23 are null in SHR-B2 only). Of the 306 divergent gene sequences, 126 result in amino acid substitution and, among these, SHR-A3 and SHR-B2 differ from one another at the amino acid level in 96 segments. Twelve pseudogenes in the RRGS had changes displacing the stop codon and creating probable functional genes in either or both SHR-A3 and SHR-B2. A further 5 alleles that encoded functional RRGS genes or open reading frames were converted to pseudogenes in either or both SHR-A3 and SHR-B2. These studies reveal that the pre-immune immunoglobulin repertoire is highly divergent among SHR lines differing in end organ injury susceptibility and this may modify immune mechanisms in hypertensive renal injury.

Mendelian and trans-generational inheritance in hypertensive renal disease

Familial risk in hypertensive renal disease has stimulated a search for genetic variation contributing to this risk. The current phase of population genetic studies has sought to associate genetic variation with disease in large populations by testing genotypes at a large number of common genetic variations in the genome, expecting that common genetic variants contributing to renal disease risk will be identified. These genome-wide association studies (GWAS) have been productive and are a clear technical success. It is also clear that narrowly defined loci and genes containing variation contributing to disease risk have been identified. Further extension and refinement of these GWAS are likely to extend this success. However, it is also clear that few if any variants with substantial effects accounting for the greatest part of heritability will be uncovered by GWAS. This raises an interesting biological question regarding where the remaining heritable risk may be located. One result of the progress of GWAS is likely to be a renewed interest in mechanisms by which related individuals can share and transmit traits independently of Mendelian inheritance. This paper reviews current progress in this area and considers other mechanisms by which familial aggregation of risk for renal disease may arise.

Long-term outcome of renal transplantation patients with Henoch-Schonlein purpura

BACKGROUND AND OBJECTIVES

Although Henoch-Schönlein purpura (HSP) is the most common form of renal vasculitis in childhood, progression to ESRD is rare, and there are few data on outcomes of renal transplantation in patients with HSP.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a matched retrospective cohort study of renal allografts using the United Network of Organ Sharing database (1987 to 2005). Of the 189,211 primary renal allografts, there were 339 with a diagnosis of HSP. The primary end point was allograft survival.

RESULTS

Compared with the remainder of the database, the HSP population was younger (25 years versus 46 years), and had a higher proportion of women (47% versus 40%), live donors (50% versus 35%), and Caucasians (77% versus 60%). Controlling for age, gender, donor source, ethnicity, and year of transplantation, death-censored graft survival for patients with HSP was 80.0% at 5 years and 58.8% at 10 years compared with 79.0% at 5 years and 55.4% at 10 years in the non-HSP population. Among patients with reported causes of graft loss, failure from recurrent disease occurred in 13.6% of patients with HSP, compared with 6.6% in the non-HSP population. When analyzing allograft survival in recipients with HSP compared with those with IgA nephropathy, there was no difference in 10-year allograft survival (58.4% and 59.3%, respectively).

CONCLUSIONS

These data indicate that although there is an increased risk of graft failure attributable to recurrent disease in patients with HSP, a diagnosis of HSP has little effect on overall renal allograft survival.

Immunoglobulin locus associates with serum IgG levels and albuminuria

The interaction between IgG and Fc-γ receptors in glomeruli contributes to the development of several types of proteinuric glomerular disease, but the involvement of immunological mechanisms in hypertensive renal injury is incompletely understood. Here, we investigated serum IgG levels in SHR-A3 rats, which develop hypertensive injury, and compared them with the injury-resistant SHR-B2 line. At 18 weeks old, SHR-A3 rats had serum total IgG levels nearly twice those of SHR-B2 rats, although subclass IgG2b was undetectable in SHR-A3 rats compared with mean levels (± SEM) of 80.7 ± 12.8 mg/dl (18 weeks) and 116.6 ± 19.0 mg/dl (30 weeks) in SHR-B2 rats. In addition, these two strains had significantly different serum levels of IgG1, IgG2a, and IgG2c; differences persisted at 30 weeks for all subclasses except IgG2a. Genetic mapping revealed that a locus on chromosome 6 linked to IgG subclass levels that affected IgG1, IgG2b, and IgG2c but not IgG2a. The mapped haplotype block contains IgH, suggesting regulation of three of four serum IgG subclass levels in cis. Resequencing revealed variation in the sequence of the Fc portion of the IgG heavy chain, which predicts important functional changes. To examine whether there is any relationship between this haplotype block and susceptibility to renal injury, we examined the effect of SHR-A3 and SHR-B2 alleles at this block on albumin excretion in an F2 intercross. Albuminuria doubled with inheritance of SHR-A3 alleles. In summary, allelic variation in IgH or nearby genes may modulate the susceptibility to hypertensive renal injury in SHR-A3 rats.

Allograft failure in kidney transplant recipients with membranoproliferative glomerulonephritis

BACKGROUND

Membranoproliferative glomerulonephritis types I (MPGN-I) and II (MPGN-II) are rare diseases that in limited case series have been reported to recur frequently in kidney transplants and have a negative impact on allograft survival.

STUDY DESIGN

Retrospective database review.

SETTING & PARTICIPANTS

189,211 primary kidney transplants in the United Network for Organ Sharing (UNOS) database from September 1987 to May 2007.

PREDICTOR OR FACTOR

MPGN-I (811 patients; 0.4%), MPGN-II (179 patients; 0.1%), other GN (58,129 patients; 30.7%), and all other diagnoses (130,092 patients; 68.7%).

OUTCOMES

Death-censored and non-death-censored allograft survival.

RESULTS

Compared with controls, patients with MPGN-I and MPGN-II were significantly younger at the time of transplant, with a median age of 36 and 27 years compared with 44 years in the GN group and 46 years in all other disease groups, respectively (all P < 0.001). Mortality in patients with MPGN-I (8.8%) was significantly lower compared with the GN (11.3%; P = 0.02) and other disease (16.6%; P < 0.001) populations and lower in those with MPGN-II (9.5%) compared with the other disease (16.6%; P = 0.01) population. Graft failure rates were significantly higher in the MPGN-I (44.5%) cohort, but not in the MPGN-II (45.3%) cohort compared with the GN (38.0%) population (P < 0.001 and P = 0.05, respectively); neither MPGN cohort differed from the other disease (43.0%) population (P = 0.4 and P = 0.5). Overall, 10-year death-censored graft survival was similar for MPGN-I (56.2%) and MPGN-II (57.5%); both were significantly worse than for GN (65.2%; P < 0.001 and P = 0.003, respectively), and only MPGN-I was significantly worse than the other disease (60.0%) population (P = 0.004). Of allograft failures with a reported cause, disease recurrence was the primary cause in 36 (14.5%) MPGN-I and 18 (29.5%) MPGN-II transplant recipients and was significantly higher compared with 879 (6.6%) GN and 1,319 (4.4%) all-other-disease recurrence failures (P < 0.001).

LIMITATIONS

Limited pretransplant clinical and biopsy data.

CONCLUSIONS

A diagnosis of MPGN-I or MPGN-II has a significant negative impact on overall primary allograft survival compared with other forms of glomerulonephritis, whereas only MPGN-I has a significant, but modest, negative effect compared with other causes of end-stage renal disease.

Urine proteome analysis in murine nephrotoxic serum nephritis

BACKGROUND

Urine contains serum proteins filtered by the glomerulus or secreted by the renal tubules and proteins produced locally by the urinary tract. Proteomic analysis of urine holds the potential as a noninvasive means of studying or monitoring disease activity. In mice, large concentrations of albumin and lipocalins have complicated the ability to identify urinary biomarkers in disease models.

METHODS

Passive nephrotoxic serum nephritis was induced in mice. Urine proteins were identified and quantified by iTRAQ and MALDI-TOF mass spectrometry. Results were compared to Western blotting and multiplex immunoassays.

RESULTS

Large concentrations of major urinary proteins dominate the urine proteome of mice even in the context of acute nephritis. Increased proteinuria caused by nephrotoxic serum nephritis is transient and includes increased albumin excretion. There were no alterations in chemokine excretion. Altered hepcidin excretion was identified, most likely reflecting local production and renal retention.

CONCLUSION

Proteomic analysis of mouse urine remains challenging due to the abundance of a limited subset of proteins. iTRAQ analysis does not circumvent these challenges, but can provide information on post-translational processing of some proteins. Hepcidin is identified as a potential urinary marker of nephritis and its role in disease pathogenesis warrants further study.

C3a receptor deficiency accelerates the onset of renal injury in the MRL/lpr mouse

The development and progression of systemic lupus erythematosus (SLE) is strongly associated with complement activation and deposition. The anaphylatoxin C3a is a product of complement activation with immunomodulatory properties, and the receptor for C3a (C3aR) is not only expressed by granulocytes and antigen presenting cell populations, but it is also strongly up-regulated in lupus prone mice with active nephritis. In order to characterize the role of the C3aR in inflammatory nephritis, we bred C3aR knock out mice onto the MRL/lpr genetic background (C3aR KO MRL). Compared to control MRL/lpr mice, C3aR KO MRL mice had elevated auto-antibody titers and an earlier onset of renal injury. At 8 weeks, renal expression of a wide range of chemokines and chemokine receptors was increased in C3aR KO MRL kidneys compared to controls. Only the expression of MCP-1 was significantly decreased in the C3aR KO MRL mice. The increased chemokine and chemokine receptor expression seen in the C3aR KO MRL mice was associated with a more rapid rise in serum creatinine and the acceleration of renal fibrosis. However, loss of the C3aR had little impact on long-term kidney injury and did not alter survival. These findings suggest that activation of the C3aR plays a protective, not pathologic, role in the early phase of inflammatory nephritis in the MRL/lpr model of SLE.

Increased survival and reduced renal injury in MRL/lpr mice treated with a novel sphingosine-1-phosphate receptor agonist

Agonists of the type 1 sphingosine-1-phosphate (S1P) receptor inhibit lymphocyte migration, causing their sequestration in lymphoid tissue. The S1P agonist FTY720 prolongs the survival of organ allografts and blocks T-cell mediated autoimmune diseases in experimental models; however, it is a non-selective agonist of four of the five S1P receptors. In this study female MRL/lpr mice, which develop an aggressive form of spontaneous autoimmune kidney disease, were treated with a more selective agonist of the type 1 receptor (KRP-203) or vehicle at 12 or 16 weeks of age. Eighty percent of the mice treated at 12 weeks, before the onset of visible disease, survived to the 24 weeks end point with decreased tubulointerstitial disease and significantly fewer infiltrating CD4(+) and CD8(+) T-cells. Only half of the control vehicle-treated mice survived. All of the mice treated at 16 weeks survived with reduced proteinuria. Mice in both groups had significant reductions in circulating lymphocytes. Mice receiving KRP-203 for 8-12 weeks had significant reductions in T-cells and consequently less adenopathy. Ex vivo treatment of lymphocytes from MRL/lpr mice with KRP-203 enhanced their apoptosis. Our study indicates that KRP-203 attenuates kidney injury in MRL/lpr mice, in part, by reducing T-cell infiltrates.

Cryptococcosis associated with crescentic glomerulonephritis

Crescentic glomerulonephritis (CGN) is an uncommon form of renal injury in childhood. Whereas many infectious processes are known to be linked to CGN, fungal infections typically are not. This report describes an 11-year-old girl who presented with CGN, cutaneous anergy, and cryptococcal mediastinitis. Whereas cryptococcal disease in children is usually associated with immunodeficiency (inherited or acquired), extensive immunologic evaluation of the patient was notable only for relative CD4 lymphopenia with normal CD4/CD8 ratios. Testing for human immunodeficiency virus was negative. Clinical and diagnostic studies are presented, along with a review of the literature regarding glomerular disease and cryptococcal infections.