Scaffold protein SH3BP2 signalosome is pivotal for immune activation in nephrotic syndrome

Despite clinical use of immunosuppressive agents, the immunopathogenesis of minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) remains unclear. Src homology 3-binding protein 2 (SH3BP2), a scaffold protein, forms an immune signaling complex (signalosome) with 17 other proteins, including phospholipase Cγ2 (PLCγ2) and Rho-guanine nucleotide exchange factor VAV2 (VAV2). Bioinformatic analysis of human glomerular transcriptome (Nephrotic Syndrome Study Network cohort) revealed upregulated SH3BP2 in MCD and FSGS. The SH3BP2 signalosome score and downstream MyD88, TRIF, and NFATc1 were significantly upregulated in MCD and FSGS. Immune pathway activation scores for Toll-like receptors, cytokine-cytokine receptor, and NOD-like receptors were increased in FSGS. Lower SH3BP2 signalosome score was associated with MCD, higher estimated glomerular filtration rate, and remission. Further work using Sh3bp2KI/KI transgenic mice with a gain-in-function mutation showed ~6-fold and ~25-fold increases in albuminuria at 4 and 12 weeks, respectively. Decreased serum albumin and unchanged serum creatinine were observed at 12 weeks. Sh3bp2KI/KI kidney morphology appeared normal except for increased mesangial cellularity and patchy foot process fusion without electron-dense deposits. SH3BP2 co-immunoprecipitated with PLCγ2 and VAV2 in human podocytes, underscoring the importance of SH3BP2 in immune activation. SH3BP2 and its binding partners may determine the immune activation pathways resulting in podocyte injury leading to loss of the glomerular filtration barrier.

The prevalence and outcomes of hyponatremia in children with COVID-19 and multisystem inflammatory syndrome in children (MIS-C)

Introduction

To assess the prevalence of hyponatremia among pediatric patients with coronavirus disease 2019 (COVID-19) and Multisystem Inflammatory Syndrome in Children (MIS-C) and determine if pediatric hyponatremia was associated with an increased length of stay, higher rates of mechanical ventilation, and/or elevated inflammatory markers on admission as compared to eunatremic patients.

Methods

Electronic health records were retrospectively analyzed for 168 children less than 18 years old with COVID-19 or MIS-C who were admitted to pediatric units within the Northwell Health system. The primary exposure was hyponatremic status (serum sodium <135 mEq/L) and the primary outcomes were length of stay, mechanical ventilation usage and increased inflammatory markers.

Results

Of the 168 children in the study cohort, 95 (56%) were admitted for COVID-19 and 73 (43.5%) for MIS-C. Overall, 60 (35.7%) patients presented with hyponatremia on admission. Patients with hyponatremia had higher rates of intensive care unit admission when compared to eunatremic patients (32/60 [53.3%] vs. 39/108 [36.1%], p = 0.030). In regression models, hyponatremia was not significantly associated with increased length of stay or mechanical ventilation rates. After adjustment for relevant confounders, hyponatremia remained associated with an increased square root CRP (β = 1.79: 95% CI: 0.22-3.36) and lower albumin levels (β = -0.22: 95% CI: -0.42--0.01).

Conclusion

Hyponatremia is common in pediatric COVID-19 and MIS-C. Hyponatremia was associated with a lower albumin and higher square root CRP levels. This may suggest an association of inflammation with lower serum sodium levels.

Abstract 082: Association Of Age And Blood Pressure Severity With ICD-10 Diagnosis Codes For Hypertension Disorders Among Youth Referred For Hypertension: Interim Analysis Of Data From Three Sites Of The Study Of The Epidemiology Of Pediatric Hypertension (SUPERHERO) Registry

Background: Secondary HTN is thought to be the main cause of HTN in young children and those with more severe HTN. However, the rising incidence of primary HTN has called this into question. Our objective was to estimate risk of secondary HTN based on ICD-10 codes due to age and BP.

Methods: The SUPERHERO Registry is a multicenter retrospective cohort of youth referred to subspecialty care for HTN. Inclusion criteria were initial visit for HTN disorder (per ICD-10) from 1/1/2016-12/31/2021 and age <19 years. Exclusion criteria were pregnancy, dialysis, or transplant per ICD-10. Exposures were age and BP, including z-scores, and outcomes were primary and secondary HTN by ICD-10, all at baseline. We used unadjusted generalized linear models to estimate risk of 1) secondary vs. primary HTN and 2) kidney vs. non-kidney secondary HTN.

Results: Median age was 14.2 years [IQR 10.5, 16.4], 52% (1703/3295) had obesity, 58% (1927/3295) had primary HTN, 9% (283/3295) had non-kidney secondary HTN, and 5% (171/3295) had kidney secondary HTN. Compared to youth <13 years old, adolescents had 38% lower risk of secondary vs. primary HTN (95% CL 0.53-0.74) and 23% lower risk of kidney vs. non-kidney secondary HTN (95% CL 0.61-0.98) (Table). A 1-unit higher systolic BP z-score was associated with 23% lower risk of secondary vs. primary HTN (95% CL 0.71-0.85) and 19% lower risk of kidney vs. non-kidney secondary HTN (95% CL 0.72-0.91).

Conclusions: Older age was associated with greater risk of primary HTN and lower risk of secondary HTN due to kidney disease. However, worse systolic BP was associated with lower risk of secondary HTN, including due to kidney disease. Ongoing analyses are validating these findings.

Abstract P093: Preterm Birth And Hypertension Severity In Youth Referred For Hypertension Disorders: A Superhero Interim Analysis

Introduction: Pediatric hypertension (HTN) is a growing concern with short and long-term adverse health effects. While children who were born preterm (<37 weeks’ gestation) likely have an increased HTN risk, it is unknown whether preterm birth is associated with more severe HTN once diagnosed.

Objective: Determine whether youth referred for HTN disorders who were born preterm are more likely to have worse blood pressure (BP).

Methods: This is a cross-sectional analysis of preliminary baseline data from The Study of the Epidemiology of Pediatric Hypertension (SUPERHERO) Registry, an ongoing multicenter retrospective cohort of youth referred to subspecialty clinics for HTN disorders. Inclusion criteria were <19 years of age, initial visit 1/01/2016-12/31/2021 (index date), and ICD-10 diagnostic codes for HTN disorders. Exclusion criteria were pregnancy, kidney failure on dialysis, or kidney transplantation by ICD-10 codes. We classified BP based on age, sex, and height per pediatric guidelines. We further defined high BP as elevated BP or any stage of HTN. Preterm birth was based on ICD-10 codes at the index date. We used unadjusted generalized linear models to estimate RR with 95% CL.

Results: In the cohort, 939/3295 (29%) identified as Black/African American, 576/3295 (17%) Hispanic/Latino, 1216/3295 (37%) were female, and the median age was 14.2 years (IQR 10.5, 16.4);1703/3295 (52%) had obesity. Only 24/3295 (1%) had an ICD-10 code for preterm birth, and 1951/3228 (60%) had stage 1 or stage 2 HTN. Preterm birth ICD-10 codes were not associated with a higher risk of high BP (RR 0.78, 95% CL 0.57 to 1.06) or a higher risk of HTN (RR 0.84, 95% CL 0.56 to 1.27).

Conclusion: Youth referred for HTN disorders who had ICD-10 codes for preterm birth did not have worse BP compared to those without these codes. It is possible that preterm birth is not accurately documented. Ongoing analyses include obtaining actual gestational age at birth and investigating the association with target organ damage.

Improving Clinical Trials for Anticomplement Therapies in Complement-Mediated Glomerulopathies: Report of a Scientific Workshop Sponsored by the National Kidney Foundation

Blocking the complement system as a therapeutic strategy has been proposed for numerous glomerular diseases but presents myriad questions and challenges, not the least of which is demonstrating efficacy and safety. In light of these potential issues and because there are an increasing number of anticomplement therapy trials either planned or under way, the National Kidney Foundation facilitated an all-virtual scientific workshop entitled "Improving Clinical Trials for Anti-Complement Therapies in Complement-Mediated Glomerulopathies." Attended by patient representatives and experts in glomerular diseases, complement physiology, and clinical trial design, the aim of this workshop was to develop standards applicable for designing and conducting clinical trials for anticomplement therapies across a wide spectrum of complement-mediated glomerulopathies. Discussions focused on study design, participant risk assessment and mitigation, laboratory measurements and biomarkers to support these studies, and identification of optimal outcome measures to detect benefit, specifically for trials in complement-mediated diseases. This report summarizes the discussions from this workshop and outlines consensus recommendations.

COVID-19 infection in a pediatric kidney transplant population: A single-center experience

BACKGROUND

The clinical course of SARS-CoV-2 in the pediatric kidney transplant population is not well described.

METHODS

We performed a retrospective cohort study of a pediatric kidney transplant population at a New York transplant center. Baseline characteristics and clinical course of patients with SARS-CoV-2 positivity (Ab or PCR) were described, and comparison between COVID-positive and COVID-negative transplant patients was performed.

RESULTS

Twenty-two patients had COVID-19 IgG testing performed, eight of whom also had PCR testing. 23% of our cohort had evidence of COVID-19 infection. Four patients had positive IgG only, and one patient had a positive PCR. All five patients with a positive COVID test were female. Two patients had COVID-19 symptoms, which were mild. Of the symptomatic patients, one had a positive PCR at time of symptoms, while the other had a negative PCR during symptoms but subsequently had positive IgG. As compared to patients with COVID-19 negative results, those with COVID-19 positivity were significantly more likely to have a known COVID-19 exposure, and were also more likely to be female. There was no significant difference in time from transplant between the groups. Those in the COVID-positive group had higher baseline antimetabolite dose and CNI troughs, although these did not reach statistical significance.

CONCLUSIONS

Pediatric kidney transplant recipients are at risk for development of COVID-19 infection. While this population may be more at risk for SARS-CoV-2 infection due to their immunosuppressed status, their clinical course appears mild and similar to a healthy pediatric population.

Diagnosis, Treatment, and Outcomes in Children With Congenital Nephrogenic Diabetes Insipidus: A Pediatric Nephrology Research Consortium Study

Background and Objectives: Congenital or primary nephrogenic diabetes insipidus (NDI) is a rare genetic disorder that severely impairs renal concentrating ability, resulting in massive polyuria. There is limited information about prognosis or evidence guiding the management of these patients, either in the high-risk period after diagnosis, or long-term. We describe the clinical presentation, genetic etiology, treatment and renal outcomes in a large group of children <21 years with NDI. Design: A multi-center retrospective chart review. Results: We report on 66 subjects from 16 centers. They were mainly male (89%) and white (67%). Median age at diagnosis was 4.2 months interquartile range (IQR 1.1, 9.8). A desmopressin acetate loading test was administered to 46% of children at a median age of 4.8 months (IQR 2.8, 7.6); only 15% had a water restriction test. Genetic testing or a known family history was present in 70% of the patients; out of those genetically tested, 89 and 11% had mutations in AVPR2 and AQP2, respectively. No positive family history or genetic testing was available for 30%. The most common treatments were thiazide diuretics (74%), potassium-sparing diuretics (67%) and non-steroidal anti-inflammatory drugs (42%). At the time of first treatment, 70 and 71% of children were below -2 standard deviations (SD) for weight and height, respectively. At last follow-up, median age was 72.3 months (IQR 40.9, 137.2) and the percentage below -2 SD improved to 29% and 38% for weight and height, respectively. Adverse outcomes included inpatient hospitalizations (61%), urologic complications (37%), and chronic kidney disease (CKD) stage 2 or higher in 23%. Conclusion: We found the majority of patients were treated with thiazides with either a potassium sparing diuretic and/or NSAIDs. Hospitalizations, urologic complications, short stature, and CKD were common. Prospective trials to evaluate different treatment strategies are needed to attempt to improve outcomes.

Arterial stiffness in childhood cancer survivors

BACKGROUND

Cardiovascular disease is prevalent among childhood cancer survivors (CCS). Arterial stiffness measured by pulse wave velocity (PWV) may be predictive of cardiovascular morbidity. Increased PWV has been seen in adults following chemotherapy.

PURPOSE

To evaluate PWV in a cohort of CCS and healthy controls.

PATIENTS AND METHODS

All participants were >6 years old. CCS were >12 months off-therapy and free of cardiac disease, diabetes, and kidney dysfunction. Height, weight, blood pressure (BP), medications, cancer diagnosis, age at diagnosis, time off therapy, chemotherapy, and radiation exposures were recorded. PWV was measured on all participants.

RESULTS

Sixty-eight CCS (mean 17.3 ± 6 years, 52.9% male), and 51 controls (mean 18.4 ± 5.5 years, 37.3% male) were evaluated. Among CCS, 34% had lymphoma, 44% leukemia, and 22% solid tumors, and 49% were exposed to radiation. CCS were off therapy 7 ± 4.2 years. Both groups were statistically similar in age, BMI, and BP. CCS ≥ 18 years old had significantly higher PWV compared to controls ≥ 18 years old (6.37 ± 0.89 vs. 5.76 ± 0.88 m/sec, P = 0.012). The relationship persisted in a regression model adjusted for age, sex, and BMI z-score (β = 0.52, 95%CI 0.051-0.979, P = 0.03). Seventy percent of CCS ≥ 18 had elevated PWV compared to established norms. Radiation therapy, anthracycline dose, and chemotherapy exposures were not predictive of increased PWV in CCS.

CONCLUSIONS

CCS ≥ 18 demonstrated prematurely elevated PVW. Further studies are needed to determine the predictive value of PWV in this population and its utility as a screening modality.

Concordance of measures of left-ventricular hypertrophy in pediatric hypertension

The American Academy of Pediatrics (AAP) recommends that any child diagnosed with hypertension have an echocardiogram to evaluate for the presence of left-ventricular (LV) hypertrophy (LVH) and advocates that LVH is an indication to initiate or intensify antihypertensive therapy. However, there is no consensus on the ideal method of defining LVH in the pediatric population. Many pediatric cardiologists rely on wall-thickness z-score of the LV posterior wall and/or interventricular septum to determine LVH. Yet, the AAP advocates using LV mass indexed to 2.7 (LVMI(2.7)) ≥ 51 g/m(2.7) to diagnose LVH. Recently, age-specific reference values for LVMI ≥ 95% were developed. The objective of the study was to determine the concordance between diagnosis of LVH by wall-thickness z-score and diagnosis by LVMI(2.7) criteria. A retrospective chart review was performed for subjects diagnosed with hypertension at a single tertiary care center (2009-2012). Echocardiogram reports were reviewed, and assessment of LVH was recorded. Diagnosis of LVH was assigned to each report reviewed according to three criteria: (1) LV wall-thickness z-score > 2.00; (2) age-specific reference values for LVMI(2.7) > 95th percentile; and (3) LVMI(2.7) > 51 g/m(2.7). Cohen's kappa statistic was used as a measurement of agreement between diagnosis by wall-thickness z-score and diagnosis using LVMI(2.7). A total of 159 echocardiograms in 109 subjects were reviewed. Subjects included 31 females and 77 males, age 13.2 ± 4.4 years, and 39 (42%) with a diagnosis of secondary hypertension. LVH was diagnosed in 31 cases (20%) based on increased wall-thickness z-score. Using LVMI(2.7) > 95%, LVH was found in 75 (47%) cases (mean LVMI(2.7)42.3 ± 17.2 g/m(2.7) [range 11.0-111 g/m(2.7)]). The wall-thickness z-score method agreed with LVMI(2.7) > 95% diagnosis 71% of the time (kappa 0.4). Using LVH criteria of LVMI(2.7) ≥ 51 g/m(2.7), 33 (21%) subjects were diagnosed with LVH. There was 79% agreement in the diagnosis of LVH between the wall-thickness z-score method and LVMI(2.7) > 51 g/m(2.7) (kappa 0.37). There is poor concordance between the diagnosis of LVH on echocardiogram reports using wall-thickness z-score and diagnosis of LVH using LVMI(2.7) criteria. It is important to establish a consensus method for diagnosing LVH because of the high frequency of cardiovascular complications in children with hypertension.

Second-line immunosuppressive treatment of childhood nephrotic syndrome: a single-center experience

Objective

Most cases of idiopathic nephrotic syndrome in childhood are responsive to corticosteroids. However, there is a small group of children that demonstrate steroid resistance (steroid-resistant nephrotic syndrome; SRNS), steroid dependence, or that frequently relapse (frequent-relapse steroid-sensitive nephrotic syndrome; FR-SSNS) which are more clinically difficult to treat. Therefore, second-line immunosuppressants, such as alkylating agents, calcineurin inhibitors, antimetabolites and, more recently, rituximab, have been used with varying success. The objective was to evaluate the response rates of various second-line therapies in the treatment of childhood nephrotic syndrome.

Study Design

A retrospective chart review of pediatric subjects with idiopathic nephrotic syndrome was conducted at a single tertiary care center (2007-2012). Drug responses were classified as complete response, partial response, and no response.

Results

Of the 188 charts reviewed, 121 children were classified as SSNS and 67 children as SRNS; 58% were classified as FR-SSNS. Sixty-five subjects were diagnosed with focal segmental glomerulosclerosis via biopsy. Follow-up ranged from 6 months to 21 years. The combined rate of complete and partial response for mycophenolate mofetil (MMF) was 65% (33/51) in SSNS and 67% (6/9) in SRNS. For tacrolimus, the response rate was 96% (22/23) for SSNS and 77% (17/22) for SRNS. Eighty-three percent (5/6) of SSNS subjects treated with rituximab went into complete remission; 60% relapsed after B-cell repletion. Eight refractory subjects were treated with combined MMF/tacrolimus/corticosteroid therapy with a 75% response rate.

Conclusion

Our experience demonstrates that older medications can be replaced with newer ones such as MMF, tacrolimus, and rituximab with good outcomes and better side effect profiles. The treatment of refractory cases with combination therapy is promising.

Endothelin antagonists in hypertension and kidney disease

The endothelin (ET) system seems to play a pivotal role in hypertension and in proteinuric kidney disease, including the micro- and macro-vascular complications of diabetes. Endothelin-1 (ET-1) is a multifunctional peptide that primarily acts as a potent vasoconstrictor with direct effects on systemic vasculature and the kidney. ET-1 and ET receptors are expressed in the vascular smooth muscle cells, endothelial cells, fibroblasts and macrophages in systemic vasculature and arterioles of the kidney, and are associated with collagen accumulation, inflammation, extracellular matrix remodeling, and renal fibrosis. Experimental evidence and recent clinical studies suggest that endothelin receptor blockade, in particular selective ETAR blockade, holds promise in the treatment of hypertension, proteinuria, and diabetes. Concomitant blockade of the ETB receptor is not usually beneficial and may lead to vasoconstriction and salt and water retention. The side-effect profile of ET receptor antagonists and relatively poor antagonist selectivity for ETA receptor are limitations that need to be addressed. This review will discuss what is currently known about the endothelin system, the role of ET-1 in the pathogenesis of hypertension and kidney disease, and summarize literature on the therapeutic potential of endothelin system antagonism.

Hydronephrosis in infants and children: natural history and risk factors for persistence in children followed by a medical service

Background:

Infants with neonatal hydronephrosis and a normal voiding cystourethrogram (VCUG) are presumed to have ureteropelvic junction obstruction (UPJO). There is little current information about the natural history of children with hydronephrosis or clinical factors that predict resolution of the radiological abnormality.

Objective:

To determine the time course until spontaneous resolution of neonatal hydronephrosis and define risk factors for persistence of the abnormality.

Methods:

This retrospective single center review examined infants and children <5 years of age with hydronephrosis who were followed for at least 12 months.

Results:

136 children were identified (96 male:40 female). The mean age at diagnosis of hydronephrosis was 3.3 ± 9.7 months and 76% of the patients were diagnosed at birth. The hydronephrosis was unilateral in 98 (72%) of cases, and hydronephrosis was at least moderate in severity in 22% of affected kidneys. At last follow-up at 30 ± 10 months, the abnormality had resolved in 77 out of 115 (67%) available patients, 30 (26%) had been referred to urology, and 12 (10%) had persistent hydronephrosis. Severity of hydronephrosis was the only clinical feature that predicted persistence of the abnormality (P < 0.001). There was an association between detection at birth and lack of resolution of hydronephrosis.

Conclusions:

Children with hydronephrosis and presumed UPJO and normal kidney parenchyma can be followed for at least 2 years to allow for spontaneous resolution before referral to urology. Serial sonography can be performed at 6 month intervals in uncomplicated cases. More severe hydronephrosis and presence of the lesion at birth may predict infants and children requiring closer observation and referral for possible surgical correction of the hydronephrosis.