Faculty Bibliography

Focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) are common forms of idiopathic nephrotic syndrome. The causes of these diseases are incompletely understood, but the response of patients to immunosuppressive therapies suggests that their pathogenesis is at least in part immune mediated. Preclinical and clinical research indicates that activation of the classical pathway of complement contributes to glomerular injury in FSGS. Glomerular IgM deposits are also prominent in some patients, raising the possibility that IgM is a trigger of classical pathway activation. In the present study, we examined the pattern of complement activation in the glomeruli and plasma of patients with nephrotic syndrome. We also tested whether patients with FSGS and MCD have elevated levels of natural IgM reactive with epitopes on glomerular endothelial cells and cardiolipin. We found evidence of classical pathway activation in patients with idiopathic nephrotic syndrome compared with healthy control subjects. We also detected higher levels of self-reactive IgM to both targets. Based on these results, IgM and classical pathway activation may contribute to disease pathogenesis in some patients with FSGS and MCD.NEW & NOTEWORTHY IgM is detected in biopsies from some patients with nephrotic syndrome, although this has been attributed to passive trapping of the protein. We found, however, that IgM colocalizes with complement activation fragments in some glomeruli. We also found that affected patients had higher levels of IgM reactive to glomerular endothelial cell epitopes. Thus, IgM activates the complement system in the glomeruli of some patients with nephrotic syndrome and may contribute to injury.

Introduction/UNASSIGNED:A critical unmet need exists for precision therapies for chronic kidney disease. GFB-887 is a podocyte-targeting, small molecule inhibitor of transient receptor potential canonical-5 (TRPC5) designed specifically to treat patients with glomerular kidney diseases characterized by an overactivation of the TRPC5-Rac1 pathway. In a first-in-human study, GFB-887 was found to be safe and well tolerated, had a pharmacokinetic (PK) profile allowing once-daily dosing, and dose dependently decreased urinary Rac1 in healthy adults. Methods/UNASSIGNED:TRACTION-2 is a phase 2a, double-blind, placebo-controlled, multiple-ascending dose study of GFB-887 in patients with focal segmental glomerulosclerosis (FSGS), treatment-resistant minimal change disease (TR-MCD), or diabetic nephropathy (DN) (NCT04387448). Adult patients on stable renin-angiotensin system blockade and/or immunosuppression with persistent proteinuria will be randomized and dosed in 3 ascending dose levels to GFB-887 or placebo for 12 weeks. Cohorts may be expanded or biomarker-enriched depending upon results of an adaptive interim analysis. Results/UNASSIGNED:The primary objective is to evaluate the effect of increasing doses of GFB-887 on proteinuria. Safety and tolerability, quality of life, pharmacokinetic/pharmacodynamic profiles, and the potential association of urinary Rac1 with efficacy will also be evaluated. The projected sample size has 80% power to detect a treatment difference in proteinuria of 54% (FSGS/TR-MCD) or 44% (DN) compared to placebo. Conclusion/UNASSIGNED:TRACTION-2 will explore whether targeted blockade of the TRPC5-Rac1 pathway with GFB-887 is an efficacious and safe treatment strategy for patients with FSGS, TR-MCD, and DN and the potential value of urinary Rac1 as a predictive biomarker of treatment response.

BACKGROUND:The G1 and G2 alleles of apolipoprotein L1 (APOL1) are common in the Black population and associated with increased risk of focal segmental glomerulosclerosis (FSGS). The molecular mechanisms linking APOL1 risk variants with FSGS are not clearly understood, and APOL1's natural absence in laboratory animals makes studying its pathobiology challenging. METHODS:In a cohort of 90 Black patients with either FSGS or minimal change disease (MCD) enrolled in the Nephrotic Syndrome Study Network (58% pediatric onset), we used kidney biopsy traits as an intermediate outcome to help illuminate tissue-based consequences of APOL1 risk variants and expression. We tested associations between APOL1 risk alleles or glomerular APOL1 mRNA expression and 83 light- or electron-microscopy traits measuring structural and cellular kidney changes. RESULTS:Under both recessive and dominant models in the FSGS patient subgroup (61%), APOL1 risk variants were significantly correlated (defined as FDR <0.1) with decreased global mesangial hypercellularity, decreased condensation of cytoskeleton, and increased tubular microcysts. No significant correlations were detected in MCD cohort. Independent of risk alleles, glomerular APOL1 expression in FSGS patients was not correlated with morphologic features. CONCLUSIONS:While APOL1-associated FSGS is associated with two risk alleles, both one and two risk alleles are associated with cellular/tissue changes in this study of FSGS patients. Our lack of discovery of a large group of tissue differences in FSGS and no significant difference in MCD may be due to the lack of power but also supports investigating whether machine learning methods may more sensitively detect APOL1-associated changes.

Background/UNASSIGNED:High data quality is of crucial importance to the integrity of research projects. In the conduct of multi-center observational cohort studies with increasing types and quantities of data, maintaining data quality is challenging, with few published guidelines. Methods/UNASSIGNED:The Cure Glomerulonephropathy (CureGN) Network has established numerous quality control procedures to manage the 70 participating sites in the United States, Canada, and Europe. This effort is supported and guided by the activities of several committees, including Data Quality, Recruitment and Retention, and Central Review, that work in tandem with the Data Coordinating Center to monitor the study. We have implemented coordinator training and feedback channels, data queries of questionable or missing data, and developed performance metrics for recruitment, retention, visit completion, data entry, recording of patient-reported outcomes, collection, shipping and accessing of biological samples and pathology materials, and processing, cataloging and accessing genetic data and materials. Results/UNASSIGNED:We describe the development of data queries and site Report Cards, and their use in monitoring and encouraging excellence in site performance. We demonstrate improvements in data quality and completeness over 4 years after implementing these activities. We describe quality initiatives addressing specific challenges in collecting and cataloging whole slide images and other kidney pathology data, and novel methods of data quality assessment. Conclusions/UNASSIGNED:This paper reports the CureGN experience in optimizing data quality and underscores the importance of general and study-specific data quality initiatives to maintain excellence in the research measures of a multi-center observational study.

Rationale & Objective/UNASSIGNED:Assessment of how patients feel and function is needed for clinical care and research for focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD). The objective of this study was to develop a patient-reported outcome assessment appropriate for use in children and adults with FSGS and MCD. Study Design/UNASSIGNED:Qualitative study using semi-structured interviews. Setting & Participants/UNASSIGNED:48 semi-structured interviews with children aged 8 to 17 years (n = 11) and adults (n = 10) with FSGS and children aged 8 to 17 (n = 11) and adults (n = 16) with MCD recruited from 3 academic medical centers. Analytical Approach/UNASSIGNED:Latent content analysis. Results/UNASSIGNED:FSGS and MCD have a pervasive and comparable impact on physical, social, and mental health-related quality of life regardless of age or diagnosis. Physical symptoms of swelling, fatigue, and pain were articulated by most participants. Disease management was also a frequent topic of discussion; participants described their experiences with medication and associated side effects, as well as lifestyle changes made to manage their disease (ie, dietary changes and frequent medical appointments). These discussions often identified a profound impact on physical abilities and life participation. In many instances, participants described the negative impact these symptoms had on their mood and sense of self, with most participants reporting feelings of anxiety. Limitations/UNASSIGNED:Participants were primarily non-Hispanic White and English speaking, which may limit generalizability. Conclusions/UNASSIGNED:Our results suggest that there are commonalities to the FSGS-MCD patient experience of health-related quality of life that will enable the generation of a disease-specific FSGS-MCD patient-reported outcomes instrument for use in children and adults. The development of this tool is intended to facilitate better care and support clinical research for these individuals.

BACKGROUND:A growing number of adolescents are coming out as transgender and gender expansive (TGE). These teenagers have been shown to have significantly worse health outcomes than their cisgender peers. Hypotheses to explain this discrepancy are based on increased stress levels surrounding the societal acceptance of gender identity. In this context, elevated allostatic load (AL), which describes the wear and tear sustained by the body in response to repeated exposure to stress, has been associated with adverse long-term health outcomes. OBJECTIVE:This protocol aims to measure AL among TGE adolescents compared with their cisgender peers and assess how AL varies depending on psychological stress and perceived societal acceptance. METHODS:This is an observational proof-of-concept pilot study in which AL will be measured by assaying an array of inflammatory cytokines and cortisol in urine, saliva, and hair samples of TGE youth, and these parameters will be compared with those of age-matched control participants. A questionnaire will assess 4 aspects of psychosocial well-being: presence and management of depression and anxiety, gender identity support by family members, gender minority stress, and degree of perceived safety in the surrounding community. Samples and surveys will be collected at 3 visits (baseline, 6 months, and 12 months). This study will incorporate TGE coinvestigators to inform all aspects of design, data collection, and analysis and ensure that practices are carried out in a respectful and sensitive manner. RESULTS:As of May 2021, the start of data collection for this project has continued to be postponed as a result of the COVID-19 pandemic, which has both impacted the functioning of the clinic and funding requests. We hope to begin participant recruitment and interviews with coinvestigators soon. CONCLUSIONS:We hypothesize that AL will be primarily influenced by psychological well-being and perceived support and that it will be similar in TGE adolescents and in age-matched cisgender control participants when acceptance and perceived support are high. The results of this study have the potential to increase our understanding of the health challenges faced by TGE individuals during adolescence as well as to show that low levels of acceptance may have detrimental health outcomes secondary to elevated ALs; this may lead to the development of a biomarker profile to assess allostatic stress in TGE patients that can be used to guide management. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)/UNASSIGNED:PRR1-10.2196/24100.

BACKGROUND:Growing evidence suggests that exposure to environmental chemicals, such as pesticides, impacts renal function and chronic kidney disease (CKD). However, it is not clear if pesticides may affect CKD progression and no studies exist in children. OBJECTIVES/OBJECTIVE:The objective of this study was to examine associations between serially measured urinary OP pesticide metabolites and clinical and laboratory measures of kidney function over time among children with CKD. METHODS:-isoprostane) were determined in the same specimens. Estimated glomerular filtration rate (eGFR), proteinuria, and blood pressure were assessed annually. RESULTS:DAPs were associated with increased KIM-1 and 8-OHdG throughout follow-up. A standard deviation increase in ∑diethyl metabolites was associated with increases of 11.9% (95% Confidence Interval (CI): 4.8%, 19.4%) and 13.2% (95% CI: 9.3%, 17.2%) in KIM-1 and 8-OHdG over time, respectively. DAPs were associated with lower eGFR at baseline and higher eGFR over subsequent years. CONCLUSIONS:These findings provide preliminary evidence suggesting that urinary DAP metabolites are associated with subclinical kidney injury among children with CKD, which may signal the potential for clinical events to manifest in the future. The results from this study are significant from both a clinical and public health perspective, given that OP pesticide exposure is a modifiable risk factor.

Background and objectives/UNASSIGNED:Altered gastrointestinal permeability in celiac disease (CD) is mediated by zonulin. The receptor for zonulin is expressed on podocytes. Therefore, we tested the effect of a gluten-free diet (GFD) on albuminuria in pediatric patients with newly diagnosed CD. Methods/UNASSIGNED:We performed a cohort study comparing urinary albumin (μg):creatinine (mg) ratio (ACR) in CD patients vs controls and in response to a GFD. Results/UNASSIGNED:Children with CD (n=46) had higher ACR compared to controls (n=21), 20.2±5.6 versus 8.4±1.1 μg/mg, P=0.16 and exceeded 30 μg/mg (microalbuminuria cut-off) in 7/46 cases. 17 patients had a follow-up assessment (interval 6.1±0.7 months) on a GFD. Baseline ACR was 20.7±5.2 that fell to 10.4±1.5 μg/mg, P=0.035. Conclusion/UNASSIGNED:Children and adolescents with newly diagnosed CD have low-grade albuminuria that is numerically higher than controls and that declined after implementation of a GFD. CD may be associated with reversible defects in the glomerular barrier.