Autoantibodies Targeting Nephrin in Podocytopathies.

BACKGROUND: Minimal change disease and primary focal segmental glomerulosclerosis in adults, along with idiopathic nephrotic syndrome in children, are immune-mediated podocytopathies that lead to nephrotic syndrome. Autoantibodies targeting nephrin have been found in patients with minimal change disease, but their clinical and pathophysiological roles are unclear. METHODS: We conducted a multicenter study to analyze antinephrin autoantibodies in adults with glomerular diseases, including minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, IgA nephropathy, antineutrophil cytoplasmic antibody-associated glomerulonephritis, and lupus nephritis, as well as in children with idiopathic nephrotic syndrome and in controls. We also created an experimental mouse model through active immunization with recombinant murine nephrin. RESULTS: The study included 539 patients (357 adults and 182 children) and 117 controls. Among the adults, antinephrin autoantibodies were found in 46 of the 105 patients (44%) with minimal change disease, 7 of 74 (9%) with primary focal segmental glomerulosclerosis, and only in rare cases among the patients with other conditions. Of the 182 children with idiopathic nephrotic syndrome, 94 (52%) had detectable antinephrin autoantibodies. In the subgroup of patients with active minimal change disease or idiopathic nephrotic syndrome who were not receiving immunosuppressive treatment, the prevalence of antinephrin autoantibodies was as high as 69% and 90%, respectively. At study inclusion and during follow-up, antinephrin autoantibody levels were correlated with disease activity. Experimental immunization induced a nephrotic syndrome, a minimal change disease-like phenotype, IgG localization to the podocyte slit diaphragm, nephrin phosphorylation, and severe cytoskeletal changes in mice. CONCLUSIONS: In this study, circulating antinephrin autoantibodies were common in patients with minimal change disease or idiopathic nephrotic syndrome and appeared to be markers of disease activity. Their binding at the slit diaphragm induced podocyte dysfunction and nephrotic syndrome, which highlights their pathophysiological significance. (Funded by Deutsche Forschungsgemeinschaft and others.).

Trends and socioeconomic inequality of the burden of congenital abnormalities of the kidney and urinary tract among children and adolescents.

BACKGROUND: Although congenital abnormalities of the kidney and urinary tract (CAKUT) is the leading cause of childhood onset chronic kidney disease (CKD) and kidney failure, comprehensive information on the disease burden among children and adolescents globally is lacking. We aim to report the trends and socioeconomic inequality of CAKUT burden for people aged 0-24 years from 1990 to 2019·. METHODS: We reported the prevalence, mortality and disability-adjusted life-years (DALYs) for CAKUT based on the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, quantified the association of disease burden and socio-demographic index (SDI), calculated the slope index of inequality (SII) the relative index of inequality (RII) and concentration index. RESULTS: In 2019, the global prevalence, mortality, and DALYs of CAKUT among individuals aged 0-24 years were 167.11 (95%Confident Interval 166.97, 167.25), 0.30 (0.29, 0.30), and 32.22 (32.16, 32.29) per 100 000 population. The greatest prevalence, mortality and DALYs were recorded in the 0-4 year age group. The greatest mortality and DALYs were recorded in low SDI countries and territories. During 1990 to 2019, the prevalence, mortality and DALYs decreased globally, while in low and low-middle countries and territories the reduction was much less slower. India, Nigeria and Pakistan had the highest DALYs. Saudi Arabia and China exhibited a markedly decrease of CAKUT burden. Globally for every 0.1 increase in SDI, there was a 20.53% reduction in mortality, a 16.31% decrease in DALYs, but a 0.38% rise in prevalence. CONCLUSIONS: Inequality for disease burden of varying SDI was increasing globally. Thus, specific preventive and health service measures are needed to reduce the global burden from CAKUT.

Metabolomic profiling of pediatric post-tonsillectomy pain: A proof-of-concept study.

INTRODUCTION: Tonsillectomies are among the most common surgical procedures in children, with over 500 000 cases annually in the United States. Despite universal administration of intraoperative opioid analgesia, three out of five children undergoing tonsillectomy report moderate-to-severe pain upon recovering from anesthesia. The underlying molecular mechanisms of post-tonsillectomy pain are not well understood, limiting the development of targeted treatment strategies. Our study aimed to identify candidate serum metabolites associated with varying severity of post-tonsillectomy pain. METHODS: Venous blood samples and pain scores were obtained from 34 children undergoing tonsillectomy ± adenoidectomy, and metabolomic analysis was performed. Supervised orthogonal projections to latent structures discriminant analysis were employed to identify differentially expressed metabolites between children with severe and mild pain, as well as between moderate and mild pain. RESULTS: Pain scores differentiated children as mild (n = 6), moderate (n = 14), or severe (n = 14). Four metabolites (fatty acid 18:0(OH), thyroxine, phosphatidylcholine 38:5, and branched fatty acids C27H54O3) were identified as candidate biomarkers that differentiated severe vs. mild post-tonsillectomy pain, the combination of which yielded an AUC of 0.91. Similarly, four metabolites (sebacic acid, dicarboxylic acids C18H34O4, hydroxy fatty acids C18H34O3, and myristoleic acid) were identified as candidate biomarkers that differentiated moderate vs. mild post-tonsillectomy pain, with AUC values ranging from 0.85 to 0.95. CONCLUSION: This study identified novel candidate biomarker panels that effectively differentiated varying severity of post-tonsillectomy pain. Further research is needed to validate these data and to explore their clinical implications for personalized pain management in children undergoing painful surgeries.

Prothrombin Knockdown Protects Podocytes and Reduces Proteinuria in Glomerular Disease.

Chronic kidney disease (CKD) is a leading cause of death, and its progression is driven by glomerular podocyte injury and loss, manifesting as proteinuria. Proteinuria includes urinary loss of coagulation zymogens, cofactors, and inhibitors. Importantly, both CKD and proteinuria significantly increase the risk of thromboembolic disease. Prior studies demonstrated that anticoagulants reduced proteinuria in rats and that thrombin injured cultured podocytes. Herein we aimed to directly determine the influence of circulating prothrombin on glomerular pathobiology. We hypothesized that (pro)thrombin drives podocytopathy, podocytopenia, and proteinuria. Glomerular proteinuria was induced with puromycin aminonucleoside (PAN) in Wistar rats. Circulating prothrombin was either knocked down using a rat-specific antisense oligonucleotide or elevated by serial intravenous infusions of prothrombin protein, which are previously established methods to model hypo- (LoPT) and hyper-prothrombinemia (HiPT), respectively. After 10 days (peak proteinuria in this model) plasma prothrombin levels were determined, kidneys were examined for (pro)thrombin co-localization to podocytes, histology, and electron microscopy. Podocytopathy and podocytopenia were determined and proteinuria, and plasma albumin were measured. LoPT significantly reduced prothrombin colocalization to podocytes, podocytopathy, and proteinuria with improved plasma albumin. In contrast, HiPT significantly increased podocytopathy and proteinuria. Podocytopenia was significantly reduced in LoPT vs. HiPT rats. In summary, prothrombin knockdown ameliorated PAN-induced glomerular disease whereas hyper-prothrombinemia exacerbated disease. Thus, (pro)thrombin antagonism may be a viable strategy to simultaneously provide thromboprophylaxis and prevent podocytopathy-mediated CKD progression.

Glucocorticoid- and pioglitazone-induced proteinuria reduction in experimental NS both correlate with glomerular ECM modulation.

Idiopathic nephrotic syndrome (NS) is a common glomerular disease. Although glucocorticoids (GC) are the primary treatment, the PPARγ agonist pioglitazone (Pio) also reduces proteinuria in patients with NS and directly protects podocytes from injury. Because both drugs reduce proteinuria, we hypothesized these effects result from overlapping transcriptional patterns. Systems biology approaches compared glomerular transcriptomes from rats with PAN-induced NS treated with GC vs. Pio and identified 29 commonly regulated genes-of-interest, primarily involved in extracellular matrix (ECM) remodeling. Correlation with clinical idiopathic NS patient datasets confirmed glomerular ECM dysregulation as a potential mechanism of injury. Cellular deconvolution in silico revealed GC- and Pio-induced amelioration of altered genes primarily within podocytes and mesangial cells. While validation studies are indicated, these analyses identified molecular pathways involved in the early stages of NS (prior to scarring), suggesting that targeting glomerular ECM dysregulation may enable a future non-immunosuppressive approach for proteinuria reduction in idiopathic NS.

Association of COVID-19 Versus COVID-19 Vaccination With Kidney Function and Disease Activity in Primary Glomerular Disease: A Report of the Cure Glomerulonephropathy Study.

RATIONALE & OBJECTIVE: Patients with glomerular disease (GN) may be at increased risk of severe COVID-19, yet concerns over vaccines causing disease relapse may lead to vaccine hesitancy. We examined the associations of COVID-19 with longitudinal kidney function and proteinuria and compared these with similar associations with COVID-19 vaccination. STUDY DESIGN: Observational cohort study from July 1, 2021, to January 1, 2023. SETTING & PARTICIPANTS: A prospective observational study network of 71 centers from North America and Europe (CureGN) with children and adults with primary minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy. EXPOSURE: COVID-19 and COVID-19 vaccination. OUTCOME: Repeated measure of estimated glomerular filtration rate (eGFR); recurrent time-to-event outcome of GN disease worsening as defined by doubling of the urinary protein-creatinine ratio (UPCR) to at least 1.5g/g or increase in dipstick urine protein by 2 ordinal levels to 3+(300mg/dL) or above. ANALYTICAL APPROACH: Interrupted time series analysis for eGFR. Prognostic matched sequential stratification recurrent event analysis for GN disease worsening. RESULTS: Among 2,055 participants, 722 (35%) reported COVID-19 infection; of these, 92 (13%) were hospitalized, and 3 died (<1%). The eGFR slope before COVID-19 infection was-1.40mL/min/1.73m2 (± 0.29 SD); within 6 months after COVID-19 infection, the eGFR slope was-4.26mL/min/1.73m2 (± 3.02 SD), which was not significantly different (P=0.34). COVID-19 was associated with increased risk of worsening GN disease activity (HR, 1.35 [95% CI, 1.01-1.80]). Vaccination was not associated with a change in eGFR (-1.34mL/min/1.73m2±0.15 SD vs-2.16mL/min/1.73m2±1.74 SD; P=0.6) or subsequent GN disease worsening (HR 1.02 [95% CI, 0.79-1.33]) in this cohort. LIMITATIONS: Infrequent or short follow-up. CONCLUSIONS: Among patients with primary GN, COVID-19 infection was severe for 1 in 8 cases and was associated with subsequent worsening of GN disease activity, as defined by proteinuria. By contrast, vaccination against COVID-19 was not associated with change in disease activity or kidney function decline. These results support COVID-19 vaccination for patients with GN. PLAIN-LANGUAGE SUMMARY: In this cohort study of 2,055 patients with minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy, COVID-19 resulted in hospitalization or death for 1 in 8 cases and was associated with a 35% increase in risk for worsening proteinuria. By contrast, vaccination did not appear to adversely affect kidney function or proteinuria. Our data support vaccination for COVID-19 in patients with glomerular disease.

Post-transplant recurrence of focal segmental glomerular sclerosis: consensus statements.

Focal segmental glomerular sclerosis (FSGS) is 1 of the primary causes of nephrotic syndrome in both pediatric and adult patients, which can lead to end-stage kidney disease. Recurrence of FSGS after kidney transplantation significantly increases allograft loss, leading to morbidity and mortality. Currently, there are no consensus guidelines for identifying those patients who are at risk for recurrence or for the management of recurrent FSGS. Our work group performed a literature search on PubMed/Medline, Embase, and Cochrane, and recommendations were proposed and graded for strength of evidence. Of the 614 initially identified studies, 221 were found suitable to formulate consensus guidelines for recurrent FSGS. These guidelines focus on the definition, epidemiology, risk factors, pathogenesis, and management of recurrent FSGS. We conclude that additional studies are required to strengthen the recommendations proposed in this review.

Inhibition of the glucocorticoid receptor attenuates proteinuric kidney diseases in multiple species.

BACKGROUND AND HYPOTHESIS: Glucocorticoids are the treatment of choice for proteinuric patients with minimal-change disease (MCD) and primary focal and segmental glomerulosclerosis (FSGS). Immunosuppressive as well as direct effects on podocytes are believed to mediate their actions. In this study, we analyzed the anti-proteinuric effects of inhibition of the glucocorticoid receptor (GR) in glomerular epithelial cells, including podocytes. METHODS: We employed genetic and pharmacological approaches to inhibit the GR. Genetically, we used Pax8-Cre/GRfl/fl mice to specifically inactivate the GR in kidney epithelial cells. Pharmacologically, we utilized a glucocorticoid antagonist called mifepristone. RESULTS: Genetic inactivation of GR, specifically in kidney epithelial cells, using Pax8-Cre/GRfl/fl mice, ameliorated proteinuria following protein overload. We further tested the effects of pharmacological GR inhibition in three models and species: the puromycin-aminonucleoside-induced nephrosis model in rats, the protein overload model in mice and the inducible transgenic NTR/MTZ zebrafish larvae with specific and reversible podocyte injury. In all three models, both pharmacological GR activation and inhibition consistently and significantly ameliorated proteinuria. Additionally, we translated our findings to humans, where three nephrotic adult patients with MCD or primary FSGS with contraindications or insufficient responses to corticosteroids, were treated with mifepristone. This treatment resulted in a clinically relevant reduction of proteinuria. CONCLUSIONS: Thus, across multiple species and proteinuria models, both genetic and pharmacological GR inhibition was at least as effective as pronounced GR activation. While, the mechanism remains perplexing, GR inhibition may be a novel and targeted therapeutic approach to treat glomerular proteinuria potentially bypassing adverse actions of steroids.

Multiomics Analysis of Plasma Proteomics and Metabolomics of Steroid Resistance in Childhood Nephrotic Syndrome Using a "Patient-Specific" Approach.

Introduction: Nephrotic syndrome (NS) occurs commonly in children with glomerular disease and glucocorticoids (GCs) are the mainstay treatment. Steroid resistant NS (SRNS) develops in 15% to 20% of children, increasing the risk of chronic kidney disease compared to steroid sensitive NS (SSNS). NS pathogenesis is unclear in most children, and no biomarkers exist that predict the development of pediatric SRNS. Methods: We studied a unique patient cohort with plasma specimens collected before GC treatment, yielding a disease-only sample not confounded by steroid-induced gene expression changes (SSNS n = 8; SRNS n = 7). A novel "patient-specific" bioinformatic approach merged paired pretreatment and posttreatment proteomic and metabolomic data and identified candidate SRNS biomarkers and altered molecular pathways in SRNS versus SSNS. Results: Joint pathway analyses revealed perturbations in nicotinate or nicotinamide and butanoate metabolic pathways in patients with SRNS. Patients with SSNS had perturbations of lysine degradation, mucin type O-glycan biosynthesis, and glycolysis or gluconeogenesis pathways. Molecular analyses revealed frequent alteration of molecules within these pathways that had not been observed by separate proteomic and metabolomic studies. We observed upregulation of NAMPT, NMNAT1, and SETMAR in patients with SRNS, in contrast to upregulation of ALDH1B1, ACAT1, AASS, ENPP1, and pyruvate in patients with SSNS. Pyruvate regulation was the change seen in our previous analysis; all other targets were novel. Immunoblotting confirmed increased NAMPT expression in SRNS and increased ALDH1B1 and ACAT1 expression in SSNS, following GC treatment. Conclusion: These studies confirmed that a novel "patient-specific" bioinformatic approach can integrate disparate omics datasets and identify candidate SRNS biomarkers not observed by separate proteomic or metabolomic analysis.

Clinical course and management of children with IgA vasculitis with nephritis.

BACKGROUND: IgA vasculitis is the most common vasculitis in children and is often complicated by acute nephritis (IgAVN). Risk of chronic kidney disease (CKD) among children with IgAVN remains unknown. This study aimed to describe the clinical management and kidney outcomes in a large cohort of children with IgAVN. METHODS: This observational cohort study used the PEDSnet database to identify children diagnosed with IgAV between January 1, 2009, and February 29, 2020. Demographic and clinical characteristics were compared among children with and without kidney involvement. For children followed by nephrology, clinical course, and management patterns were described. Patients were divided into four categories based on treatment: observation, renin-angiotensin-aldosterone system (RAAS) blockade, corticosteroids, and other immunosuppression, and outcomes were compared among these groups. RESULTS: A total of 6802 children had a diagnosis of IgAV, of whom 1139 (16.7%) were followed by nephrology for at least 2 visits over a median follow-up period of 1.7 years [0.4,4.2]. Conservative management was the most predominant practice pattern, consisting of observation in 57% and RAAS blockade in 6%. Steroid monotherapy was used in 29% and other immunosuppression regimens in 8%. Children receiving immunosuppression had higher rates of proteinuria and hypertension compared to those managed with observation (p < 0.001). At the end of follow-up, 2.6 and 0.5% developed CKD and kidney failure, respectively. CONCLUSIONS: Kidney outcomes over a limited follow-up period were favorable in a large cohort of children with IgAV. Immunosuppressive medications were used in those with more severe presentations and may have contributed to improved outcomes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Psychosocial supports within pediatric nephrology practices: A pediatric nephrology research consortium survey.

BACKGROUND: The landscape of available psychosocial services within pediatric nephrology care is poorly characterized. However, the effects of kidney disease on emotional health and health-related quality of life are well documented, as is the impact of social determinants of health on kidney disease outcomes. The objectives of this study were to assess pediatric nephrologists' perceptions of available psychosocial services and to elucidate inequities in access to psychosocial care. METHODS: A web-based survey was distributed to members of the Pediatric Nephrology Research Consortium (PNRC). Quantitative analyses were performed. RESULTS: We received responses from 49 of the 90 PNRC centers. With regards to dedicated services, social work was most commonly available (45.5-100%), followed by pediatric psychology (0-57.1%) and neuropsychology (0-14.3%), with no centers having embedded psychiatry. Availability of psychosocial providers was positively associated with nephrology division size, such that as center size increased, access to various psychosocial providers increased. Notably, the majority of respondents indicated that perceived need for psychosocial support exceeds that which is currently available, even at centers with higher levels of current support. CONCLUSIONS: Within the US, there is wide variability in the availability of psychosocial services within pediatric nephrology centers despite a well-documented necessity for the provision of holistic care. Much work remains to better understand the variation in funding for psychosocial services and in utilization of psychosocial professionals in the pediatric nephrology clinic, and to inform key best practices for addressing the psychosocial needs of patients with kidney disease.

Evaluating Kidney Function Decline in Children with Chronic Kidney Disease Using a Multi-Institutional Electronic Health Record Database.

BACKGROUND: The objectives of this study were to use electronic health record data from a US national multicenter pediatric network to identify a large cohort of children with CKD, evaluate CKD progression, and examine clinical risk factors for kidney function decline. METHODS: This retrospective cohort study identified children seen between January 1, 2009, to February 28, 2022. Data were from six pediatric health systems in PEDSnet. We identified children aged 18 months to 18 years who met criteria for CKD: two eGFR values <90 and ≥15 ml/min per 1.73 m2 separated by ≥90 days without an intervening value ≥90. CKD progression was defined as a composite outcome: eGFR <15 ml/min per 1.73 m2, ≥50% eGFR decline, long-term dialysis, or kidney transplant. Subcohorts were defined based on CKD etiology: glomerular, nonglomerular, or malignancy. We assessed the association of hypertension (≥2 visits with hypertension diagnosis code) and proteinuria (≥1 urinalysis with ≥1+ protein) within 2 years of cohort entrance on the composite outcome. RESULTS: Among 7,148,875 children, we identified 11,240 (15.7 per 10,000) with CKD (median age 11 years, 50% female). The median follow-up was 5.1 (interquartile range 2.8-8.3) years, the median initial eGFR was 75.3 (interquartile range 61-83) ml/min per 1.73 m2, 37% had proteinuria, and 35% had hypertension. The following were associated with CKD progression: lower eGFR category (adjusted hazard ratio [aHR] 1.44 [95% confidence interval (95% CI), 1.23 to 1.69], aHR 2.38 [95% CI, 2.02 to 2.79], aHR 5.75 [95% CI, 5.05 to 6.55] for eGFR 45-59 ml/min per 1.73 m2, 30-44 ml/min per 1.73 m2, 15-29 ml/min per 1.73 m2 at cohort entrance, respectively, when compared with eGFR 60-89 ml/min per 1.73 m2), glomerular disease (aHR 2.01 [95% CI, 1.78 to 2.28]), malignancy (aHR 1.79 [95% CI, 1.52 to 2.11]), proteinuria (aHR 2.23 [95% CI, 1.89 to 2.62]), hypertension (aHR 1.49 [95% CI, 1.22 to 1.82]), proteinuria and hypertension together (aHR 3.98 [95% CI, 3.40 to 4.68]), count of complex chronic comorbidities (aHR 1.07 [95% CI, 1.05 to 1.10] per additional comorbid body system), male sex (aHR 1.16 [95% CI, 1.05 to 1.28]), and younger age at cohort entrance (aHR 0.95 [95% CI, 0.94 to 0.96] per year older). CONCLUSIONS: In large-scale real-world data for children with CKD, disease etiology, albuminuria, hypertension, age, male sex, lower eGFR, and greater medical complexity at start of follow-up were associated with more rapid decline in kidney function.

Exploring the Role of Antithrombin in Nephrotic Syndrome-Associated Hypercoagulopathy: A Multi-Cohort Study and Meta-Analysis.

BACKGROUND: Nephrotic syndrome is associated with an acquired hypercoagulopathy that is thought to drive its predisposition for venous thromboembolism. Previous studies have suggested that urinary antithrombin (AT) loss leading to acquired AT deficiency is the primary mechanism underlying this hypercoagulopathy, but this hypothesis has not been directly tested. The objectives of this study were to test the influence of AT levels on hypercoagulopathy in nephrotic syndrome patient samples and perform meta-analyses to evaluate the likelihood of AT deficiency in patients with nephrotic syndrome. METHODS: Samples from three independent nephrotic syndrome cohorts were analyzed. AT antigen and activity assays were performed using ELISA and amidolytic assays, respectively. Plasma thrombin generation, albumin, and urine protein-to-creatinine ratios were determined using established methods. Meta-analyses were performed by combining these new data with previously published data. RESULTS: AT levels were not consistently related to either plasma albumin or proteinuria. AT was quantitatively related to hypercoagulopathy in adult nephrotic syndrome, whereas AT activity was inconsistently associated with hypercoagulopathy in childhood nephrotic syndrome. Notably, hypercoagulopathy did not differ between patients with normal AT levels and those with levels below the threshold used to define clinical AT deficiency (<70%). Moreover, ex vivo AT supplementation did not significantly alter hypercoagulopathy in AT-deficient plasma samples. The meta-analyses demonstrated that AT deficiency was not a uniform feature of nephrotic syndrome and was more common in children than adults. CONCLUSIONS: These data suggest that AT deficiency plays only a limited role in the mechanisms underlying the acquired hypercoagulopathy of nephrotic syndrome. Moreover, AT deficiency was not present in all patients with nephrotic syndrome and was more likely in children than adults despite the higher risk for venous thromboembolism in adults than children.

Pioglitazone enhances proteinuria reduction in complicated pediatric nephrotic syndrome.

BACKGROUND: Nephrotic syndrome (NS) is a common pediatric kidney disease, yet current treatments for complicated NS are only partially effective and have significant toxicity. There is no Food and Drug Administration (FDA)- or European Medicines Agency (EMA)-approved safe and effective treatment for NS. Thiazolidinediones (TZDs) have been shown to reduce proteinuria in both diabetic and non-diabetic kidney disease and in preclinical studies to directly protect podocytes from injury and reduce proteinuria. Here, we report on the potential utility of the addition of the TZD pioglitazone (PIO) to enhance proteinuria reduction in 8 children and young adults with steroid dependent NS and steroid resistant NS. METHODS: Clinical data were analyzed in comparable time periods before and after the addition of PIO to their medical regimens. Eight NS patients with minimal change NS (n = 2), focal segmental glomerulosclerosis (FSGS) (n = 4), or collapsing FSGS (n = 2) were evaluated. RESULTS: Prior to PIO initiation, all children and young adults had already received multiple immunosuppressive medications (mean = 3.75). Five of eight patients (63%; "Responders") had notable proteinuria reduction within 1 month of PIO initiation (62% reduction; P = 0.04) and normalization within 6 months (97% reduction; P = 0.04). PIO-related benefits among the responders included notable increases in serum albumin (2.5 to 3.7 g/dl; P = 0.08), dramatic reductions in hospitalizations for IV albumin infusions and diuresis (11 to 0; P < 0.01), and considerable reduction in total immunosuppression (43% reduction; P > 0.1). Importantly, no patients experienced any adverse events attributable to PIO during a total of 136 patient-months of treatment. CONCLUSIONS: While confirmatory safety and efficacy studies are needed, these findings suggest pioglitazone (a non-immunosuppressive drug) may be useful to enhance proteinuria reduction in some children and young adults with complicated NS. A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinical presentation and management of nephrotic syndrome in the first year of life: A report from the Pediatric Nephrology Research Consortium.

Background and objectives: Nephrotic syndrome (NS) in the first year of life is called congenital (CNS) if diagnosed between 0-3 months, or infantile (INS) if diagnosed between 3-12 months of age. The aim of this study was to determine if there were clinically meaningful differences between CNS and INS patients, regarding clinical presentation, management and outcomes. Design setting participants and measurements: Eleven Pediatric Nephrology Research Consortium sites participated in the study, using IRB-approved retrospective chart reviews of CNS and INS patients born between 1998 and 2019. Data were collected on patient characteristics, pertinent laboratory tests, provided therapy, timing of unilateral/bilateral nephrectomy and initiation of renal replacement therapy (RRT). Results: The study included 69 patients, 49 with CNS and 20 with INS, with a median age at diagnosis of 1 and 6 months, respectively. Management for the two groups was similar regarding nutrition, thyroxin supplementation, immunoglobulin administration, and thrombosis prophylaxis. Within the first 2 months after diagnosis, daily albumin infusions were used more often in CNS vs. INS patients (79 vs. 30%; p = 0.006), while weekly infusions were more common in INS patients (INS vs. CNS: 50 vs. 3%; p = 0.001). During the 6 months preceding RRT, albumin infusions were more frequently prescribed in CNS vs. INS (51 vs. 15%; p = 0.007). Nephrectomy was performed more often in CNS (78%) than in INS (50%; p = 0.02). End-stage kidney disease tended to be more common in children with CNS (80%) vs. INS (60%; p = 0.09). Conclusion: Compared to INS, patients with CNS had a more severe disease course, requiring more frequent albumin infusions, and earlier nephrectomy and RRT. Despite center-specific variations in patient care, 20-40% of these patients did not require nephrectomy or RRT.

Skeletal Outcomes in Children and Young Adults with Glomerular Disease.

BACKGROUND: Children with glomerular disease have unique risk factors for compromised bone health. Studies addressing skeletal complications in this population are lacking. METHODS: This retrospective cohort study utilized data from PEDSnet, a national network of pediatric health systems with standardized electronic health record data for more than 6.5 million patients from 2009 to 2021. Incidence rates (per 10,000 person-years) of fracture, slipped capital femoral epiphysis (SCFE), and avascular necrosis/osteonecrosis (AVN) in 4598 children and young adults with glomerular disease were compared with those among 553,624 general pediatric patients using Poisson regression analysis. The glomerular disease cohort was identified using a published computable phenotype. Inclusion criteria for the general pediatric cohort were two or more primary care visits 1 year or more apart between 1 and 21 years of age, one visit or more every 18 months if followed >3 years, and no chronic progressive conditions defined by the Pediatric Medical Complexity Algorithm. Fracture, SCFE, and AVN were identified using SNOMED-CT diagnosis codes; fracture required an associated x-ray or splinting/casting procedure within 48 hours. RESULTS: We found a higher risk of fracture for the glomerular disease cohort compared with the general pediatric cohort in girls only (incidence rate ratio [IRR], 1.6; 95% CI, 1.3 to 1.9). Hip/femur and vertebral fracture risk were increased in the glomerular disease cohort: adjusted IRR was 2.2 (95% CI, 1.3 to 3.7) and 5 (95% CI, 3.2 to 7.6), respectively. For SCFE, the adjusted IRR was 3.4 (95% CI, 1.9 to 5.9). For AVN, the adjusted IRR was 56.2 (95% CI, 40.7 to 77.5). CONCLUSIONS: Children and young adults with glomerular disease have significantly higher burden of skeletal complications than the general pediatric population.

Utility of the 2018 revised ISN/RPS thresholds for glomerular crescents in childhood-onset lupus nephritis: a Pediatric Nephrology Research Consortium study.

BACKGROUND: The revised 2018 ISN/RPS Classification System for lupus nephritis (LN) includes calculations for both activity index (A.I.) and chronicity index (C.I.). Unchanged were the thresholds of < 25%, 25-50%, and > 50% crescents to distinguish between mild, moderate, and severe activity/chronicity. We aimed to evaluate these thresholds for percent crescents in childhood-onset LN. METHODS: Eighty-six subjects < 21 years of age were enrolled from the Pediatric Glomerulonephritis with Crescents Registry, a retrospective multi-center cohort sponsored by the Pediatric Nephrology Research Consortium. Thresholds of 10%, 25%, and 50% for both cellular/fibrocellular and fibrous crescents were interrogated for primary outcomes of kidney failure, eGFR, and eGFR slope. RESULTS: Median age at time of initial biopsy was 14 years (range 1-21). Median follow-up time was 3 years (range 1-11). Cumulative incidence of kidney failure was 6% at 1 year and 10% at latest follow-up. Median eGFR slope was - 18 mL/1.73 m2/min (IQR - 51 to + 8) at 1 year and - 3 mL/min/1.73 m2/year (IQR - 19 to + 6) at latest follow-up. We found no difference in kidney failure at the proposed < 25% and 25-50% cellular crescents thresholds, and thus added a new provisional threshold of 10% that better predicted outcomes in children. Moreover, use of 10% and 25% thresholds for fibrous crescents showed a fourfold and sevenfold increase in risk of kidney failure. CONCLUSIONS: In children with crescentic LN, use of 10% and 25% thresholds for cellular crescents better reflects disease activity, while these thresholds for fibrous crescents better discriminates kidney disease outcomes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Advances in proteomic profiling of pediatric kidney diseases.

Chronic kidney disease (CKD) can progress to kidney failure and require dialysis or transplantation, while early diagnosis can alter the course of disease and lead to better outcomes in both pediatric and adult patients. Significant CKD comorbidities include the manifestation of cardiovascular disease, heart failure, coronary disease, and hypertension. The pathogenesis of chronic kidney diseases can present as subtle and especially difficult to distinguish between different glomerular pathologies. Early detection of adult and pediatric CKD and detailed mechanistic understanding of the kidney damage can be helpful in delaying or curtailing disease progression via precise intervention toward diagnosis and prognosis. Clinically, serum creatinine and albumin levels can be indicative of CKD, but often are a lagging indicator only significantly affected once kidney function has severely diminished. The evolution of proteomics and mass spectrometry technologies has begun to provide a powerful research tool in defining these mechanisms and identifying novel biomarkers of CKD. Many of the same challenges and advances in proteomics apply to adult and pediatric patient populations. Additionally, proteomic analysis of adult CKD patients can be transferred directly toward advancing our knowledge of pediatric CKD as well. In this review, we highlight applications of proteomics that have yielded such biomarkers as PLA2R, SEMA3B, and other markers of membranous nephropathy as well as KIM-1, MCP-1, and NGAL in lupus nephritis among other potential diagnostic and prognostic markers. The potential for improving the clinical toolkit toward better treatment of pediatric kidney diseases is significantly aided by current and future development of proteomic applications.