Exome capture reveals ZNF423 and CEP164 mutations, linking renal ciliopathies to DNA damage response signaling.

Nephronophthisis-related ciliopathies (NPHP-RC) are degenerative recessive diseases that affect kidney, retina, and brain. Genetic defects in NPHP gene products that localize to cilia and centrosomes defined them as "ciliopathies." However, disease mechanisms remain poorly understood. Here, we identify by whole-exome resequencing, mutations of MRE11, ZNF423, and CEP164 as causing NPHP-RC. All three genes function within the DNA damage response (DDR) pathway. We demonstrate that, upon induced DNA damage, the NPHP-RC proteins ZNF423, CEP164, and NPHP10 colocalize to nuclear foci positive for TIP60, known to activate ATM at sites of DNA damage. We show that knockdown of CEP164 or ZNF423 causes sensitivity to DNA damaging agents and that cep164 knockdown in zebrafish results in dysregulated DDR and an NPHP-RC phenotype. Our findings link degenerative diseases of the kidney and retina, disorders of increasing prevalence, to mechanisms of DDR.

NSAID-associated acute kidney injury in hospitalized children - a prospective Pediatric Nephrology Research Consortium study.

BACKGROUND: Acute kidney injury (AKI) in children has serious short-term and long-term consequences. We sought 1) to prospectively describe NSAID-associated AKI in hospitalized children; 2) to determine if NSAID-associated AKI was more severe in younger children < 5 years; and 3) to follow outcomes after hospitalization for NSAID-associated AKI. METHODS: This was a prospective, multi-center study in hospitalized children 1 month to 18 years. Parents/guardians were given a brief questionnaire to determine the dosing, duration, and type of NSAIDs given. Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine criteria were used to stage AKI severity. Patients with other causes of AKI were excluded (e.g., other nephrotoxins, sepsis, malignancy, etc.). RESULTS: We identified 25 patients with NSAID-associated AKI, accounting for 3.1% of AKI. All 25 had AKI upon hospital presentation. The median age was 15.5 years, and 20/25 (80%) had volume depletion. Median duration of NSAID use was 2 days, and 63% of patients took the normal recommended NSAID dose. Median hospital length of stay was 4 days, and none required dialysis. At the most recent estimated glomerular filtration rate (eGFR) after discharge (available in 17/25 patients), only 4/17 (24%) had eGFR ≥ 90 ml/min/1.73 m2, and 13/17 (76%) had eGFR 60 to < 90 ml/min/1.73 m2, indicative of abnormal kidney function. CONCLUSIONS: NSAID-associated AKI usually occurs with recommended NSAID dosing in the setting of dehydration. Follow-up after AKI showed a substantial rate of CKD. Therefore, we recommend that NSAIDs should not be used in dehydrated children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinical presentation and outcome of pediatric ANCA-associated glomerulonephritis.

BACKGROUND: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a small- and medium-sized vasculitis classically seen in adult patients, with peak onset near the fifth to seventh decade of life. There is little data on ANCA-associated vasculitis in pediatric patients, and most studies have limited follow-up. METHODS: This is a retrospective chart review of 22 patients with ANCA-positive glomerulonephritis in a single institution from 1991 to 2013. RESULTS: Of the 22 patients, eight (36 %) required renal replacement therapy (RRT) at diagnosis; four of these patients recovered sufficient renal function to initially discontinue dialysis. Five patients (23 %) were treated with plasmapheresis at presentation. The median time from presentation until first clinical or serologic relapse was 1.7 ± 1.2 years. After a median follow-up of 5.8 years, just over half of our patients had chronic kidney disease (CKD) stages 1-3 (55 %). Seven (32 %) patients progressed to end-stage renal disease (ESRD) and eventually required kidney transplant. CONCLUSION: ANCA-associated glomerulonephritis is a rare disorder in children. Presentation and outcomes vary significantly among patients. More research is required to follow these patients who are diagnosed in childhood to further characterize the long-term outcome of the disease.

Nonsteroidal anti-inflammatory drugs are an important cause of acute kidney injury in children.

OBJECTIVE: To characterize nonsteroidal anti-inflammatory drug (NSAID)-associated acute kidney injury (AKI) in children. STUDY DESIGN: We conducted a retrospective chart review of children diagnosed with AKI through the use of International Classification of Diseases, Ninth Revision diagnosis code 584.5 or 584.9 from January 1999 to June 2010. Medical records were reviewed to confirm the diagnosis of AKI and to quantify NSAID administration. Pediatric RIFLE criteria were used to codify AKI. Patients were not classified as having NSAID-associated AKI if they had a diagnosis explaining AKI or comorbid clinical conditions predisposing to AKI development. RESULTS: Patients (N=1015) were identified through International Classification of Diseases, Ninth Revision screening. Twenty-one children had clinical, laboratory, and radiographic studies suggesting NSAID-associated acute tubular necrosis and 6 had findings suggesting NSAID-associated acute interstitial nephritis, representing 2.7% (27 of 1015) of the total cohort with AKI and 6.6% when excluding complex patients with multifactorial AKI. Children with NSAID-associated AKI had a median (range) age of 14.7 years (0.5-17.7 years); 4 patients (15%) were <5 years old. Fifteen of 20 children (75%) for whom dosing data were available received NSAIDs within recommended dosing limits. Patients<5 years old were more likely to require dialysis (100% vs 0%, P<.001), intensive care unit admission (75% vs 9%, P=.013), and a longer length of stay (median 10 vs 7 days, P=.037). CONCLUSIONS: NSAID-associated AKI accounted for 2.7% of AKI in this pediatric population. AKI typically occurred after the administration of correctly dosed NSAIDs. Young children with NSAID-associated AKI may have increased disease severity.

Clinical and Histopathologic Characteristics of Pediatric Patients With Primary Membranous Nephropathy.

Introduction: Primary membranous nephropathy (PMN) is uncommon in children. Therefore, data on the clinical course of affected children are scarce. In recent years, several novel antigens have been implicated in the pathogenesis of PMN. However, the histopathologic characteristics of pediatric patients with PMN remain poorly represented in the literature. Methods: We have retrospectively analyzed the clinical presentation and outcomes data of 21 children with PMN from 3 centers in the United States. In addition, we have identified novel antigens in biopsy specimens from these patients and correlated their presence or absence to clinical outcomes. Finally, we compared the results of the novel antigen staining from our clinical cohort to a validation cohort of 127 biopsy specimens from children with PMN at Arkana Laboratories. Results: The data from the 2 cohorts demonstrated similar overall antigen positivity rates of 62% to 63%, with phospholipase A2 receptor (PLA2R) and exostosin 1 (EXT1) being the most commonly found antigens. Results from the clinical cohort showed that overall, the kidney prognosis for children with PMN was good, with 17 of 21 patients entering a complete or partial remission. Children who were positive for PLA2R or EXT1 were significantly more likely to enter remission than those in the antigen negative group. Conclusion: Approximately 60% of pediatric membranous cases are positive for a novel antigen on kidney biopsy and the clinical prognosis is generally favorable. More studies are needed to understand the clinical implications of each specific novel antigen.

A 25-year experience with pediatric anti-glomerular basement membrane disease.

Anti-glomerular basement membrane (anti-GBM) disease, which is extremely uncommon in children, is characterized by rapidly progressive glomerulonephritis (RPGN) and autoantibodies against GBM collagen. Pulmonary hemorrhage is the third component in Goodpasture Syndrome. Cigarette smoking and exposure to hydrocarbons have been linked to anti-GBM disease in adults, but such an association has not been established in children. We reviewed renal biopsy and autopsy specimens over 25 years from a major tertiary care U.S. children's hospital, diagnosing anti-GBM by clinical RPGN, crescentic glomerulonephritis, and linear immunofluorescence (IF) immunoglobulin G staining in patients under 18 years of age. We identified four patients, with and without pulmonary manifestations. The sole autopsy case showed diagnostic IF despite undetectable serum anti-GBM antibodies and positive testing for serum anti-neutrophil cytoplasmic antibodies (ANCA). Three patients have survived 1-18 years following diagnosis, one of whom is recovering renal function. One adolescent had a history of smoking cigarettes and one had a probable hydrocarbon exposure. Anti-GBM disease is unusual in children, and the relationship to inhaled agents is incompletely understood. Serum anti-GBM antibodies are typically present, but cases with undetectable levels can occur. Some patients are anti-GBM and ANCA positive, with a small subset ANCA-positive, anti-GBM-negative. Ours is the first such described pediatric case.

Chronic Inflammation in Chronic Kidney Disease Progression: Role of Nrf2.

Despite recent advances in the management of chronic kidney disease (CKD), morbidity and mortality rates in these patients remain high. Although pressure-mediated injury is a well-recognized mechanism of disease progression in CKD, emerging data indicate that an intermediate phenotype involving chronic inflammation, oxidative stress, hypoxia, senescence, and mitochondrial dysfunction plays a key role in the etiology, progression, and pathophysiology of CKD. A variety of factors promote chronic inflammation in CKD, including oxidative stress and the adoption of a proinflammatory phenotype by resident kidney cells. Regulation of proinflammatory and anti-inflammatory factors through NF-κB- and nuclear factor, erythroid 2 like 2 (Nrf2)-mediated gene transcription, respectively, plays a critical role in the glomerular and tubular cell response to kidney injury. Chronic inflammation contributes to the decline in glomerular filtration rate (GFR) in CKD. Whereas the role of chronic inflammation in diabetic kidney disease (DKD) has been well-elucidated, there is now substantial evidence indicating unresolved inflammatory processes lead to fibrosis and eventual end-stage kidney disease (ESKD) in several other diseases, such as Alport syndrome, autosomal-dominant polycystic kidney disease (ADPKD), IgA nephropathy (IgAN), and focal segmental glomerulosclerosis (FSGS). In this review, we aim to clarify the mechanisms of chronic inflammation in the pathophysiology and disease progression across the spectrum of kidney diseases, with a focus on Nrf2.

Bleeding risk for surgical dialysis procedures in children with hemolytic uremic syndrome.

Children with hemolytic uremic syndrome (HUS) frequently develop acute kidney injury (AKI) requiring renal replacement therapy (RRT). Peritoneal dialysis (PD) is commonly used. Despite high rates of thrombocytopenia, there is concern that platelet transfusions may worsen HUS by exacerbating microthrombi formation. We evaluated bleeding risk for PD catheter placement with or without central venous catheter (CVC) placement in children with HUS. Records from 1998 to 2007 were searched. Data regarding patient demographics, PD catheter placement, CVC placement, occurrence of procedure-associated bleeding, and time from insertion to removal of PD catheter were collected. Patients were stratified according to those who received and those who did not receive platelet transfusions. Seventy-three patients were identified. Twenty-two (30%) patients received platelet transfusion while 51 (70%) did not. Mean preoperative platelet counts were 37,600+/-21,900/mm(3) in patients receiving transfusions and 64,800 +/- 38,800/mm(3) in patients not receiving transfusions. Sixty-seven children (92%) also underwent CVC placement. There were no bleeding complications related to these procedures in either group. No differences in time to removal of the PD catheter were detected. Although caution and sound clinical judgment must be exercised, our findings suggest that PD catheter and CVC placement can be accomplished safely in most children with HUS, without need for platelet transfusion in spite of the associated thrombocytopenia.

Considerations on equity in management of end-stage kidney disease in low- and middle-income countries.

Achievement of equity in health requires development of a health system in which everyone has a fair opportunity to attain their full health potential. The current, large country-level variation in the reported incidence and prevalence of treated end-stage kidney disease indicates the existence of system-level inequities. Equitable implementation of kidney replacement therapy (KRT) programs must address issues of availability, affordability, and acceptability. The major structural factors that impact equity in KRT in different countries are the organization of health systems, overall health care spending, funding and delivery models, and nature of KRT prioritization (transplantation, hemodialysis or peritoneal dialysis, and conservative care). Implementation of KRT programs has the potential to exacerbate inequity unless equity is deliberately addressed. In this review, we summarize discussions on equitable provision of KRT in low- and middle-income countries and suggest areas for future research.

Supportive care for end-stage kidney disease: an integral part of kidney services across a range of income settings around the world.

A key component of treatment for all people with advanced kidney disease is supportive care, which aims to improve quality of life and can be provided alongside therapies intended to prolong life, such as dialysis. This article addresses the key considerations of supportive care as part of integrated end-stage kidney disease care, with particular attention paid to programs in low- and middle-income countries. Supportive care should be an integrated component of care for patients with advanced chronic kidney disease, patients receiving kidney replacement therapy (KRT), and patients receiving non-KRT conservative care. Five themes are identified: improving information on prognosis and support, developing context-specific evidence, establishing appropriate metrics for monitoring care, clearly communicating the role of supportive care, and integrating supportive care into existing health care infrastructures. This report explores some general aspects of these 5 domains, before exploring their consequences in 4 health care situations/settings: in people approaching end-stage kidney disease in high-income countries and in low- and middle-income countries, and in people discontinuing KRT in high-income countries and in low- and middle-income countries.