Clinical Characteristics and Treatment Patterns of Children and Adults With IgA Nephropathy or IgA Vasculitis: Findings From the CureGN Study

Introduction: The Cure Glomerulonephropathy Network (CureGN) is a 66-center longitudinal observational study of patients with biopsy-confirmed minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy (IgAN), including IgA vasculitis (IgAV). This study describes the clinical characteristics and treatment patterns in the IgA cohort, including comparisons between IgAN versus IgAV and adult versus pediatric patients. Methods: Patients with a diagnostic kidney biopsy within 5 years of screening were eligible to join CureGN. This is a descriptive analysis of clinical and treatment data collected at the time of enrollment. Results: A total of 667 patients (506 IgAN, 161 IgAV) constitute the IgAN/IgAV cohort (382 adults, 285 children). At biopsy, those with IgAV were younger (13.0 years vs. 29.6 years, P < 0.001), more frequently white (89.7% vs. 78.9%, P = 0.003), had a higher estimated glomerular filtration rate (103.5 vs. 70.6 ml/min per 1.73 m2, P < 0.001), and lower serum albumin (3.4 vs. 3.8 g/dl, P < 0.001) than those with IgAN. Adult and pediatric individuals with IgAV were more likely than those with IgAN to have been treated with immunosuppressive therapy at or prior to enrollment (79.5% vs. 54.0%, P < 0.001). Conclusion: This report highlights clinical differences between IgAV and IgAN and between children and adults with these diagnoses. We identified differences in treatment with immunosuppressive therapies by disease type. This description of baseline characteristics will serve as a foundation for future CureGN studies

Telomerase expression marks transitional growth-associated skeletal progenitor/stem cells: mTert marks skeletal progenitor/stem cells

©2021 The Authors. Stem Cells published by Wiley Periodicals LLC on behalf of AlphaMed Press. Skeletal progenitor/stem cells (SSCs) play a critical role in postnatal bone growth and maintenance. Telomerase (Tert) activity prevents cellular senescence and is required for maintenance of stem cells in self-renewing tissues. Here we investigated the role of mTert-expressing cells in postnatal mouse long bone and found that mTert expression is enriched at the time of adolescent bone growth. mTert-GFP+ cells were identified in regions known to house SSCs, including the metaphyseal stroma, growth plate, and the bone marrow. We also show that mTert-expressing cells are a distinct SSC population with enriched colony-forming capacity and contribute to multiple mesenchymal lineages, in vitro. In contrast, in vivo lineage-tracing studies identified mTert+ cells as osteochondral progenitors and contribute to the bone-forming cell pool during endochondral bone growth with a subset persisting into adulthood. Taken together, our results show that mTert expression is temporally regulated and marks SSCs during a discrete phase of transitional growth between rapid bone growth and maintenance

Dormant Intestinal Stem Cells Are Regulated by PTEN and Nutritional Status

The cellular and molecular mechanisms underlying adaptive changes to physiological stress within the intestinal epithelium remain poorly understood. Here, we show that PTEN, a negative regulator of the PI3K→AKT→mTORC1-signaling pathway, is an important regulator of dormant intestinal stem cells (d-ISCs). Acute nutrient deprivation leads to transient PTEN phosphorylation within d-ISCs and a corresponding increase in their number. This release of PTEN inhibition renders d-ISCs functionally poised to contribute to the regenerative response during re-feeding via cell-autonomous activation of the PI3K→AKT→mTORC1 pathway. Consistent with its role in mediating cell survival, PTEN is required for d-ISC maintenance at baseline, and intestines lacking PTEN have diminished regenerative capacity after irradiation. Our results highlight a PTEN-dependent mechanism for d-ISC maintenance and further demonstrate the role of d-ISCs in the intestinal response to stress

Mouse telomerase reverse transcriptase (mTert) expression marks slowly cycling intestinal stem cells

The intestinal epithelium is maintained by a population of rapidly cycling (Lgr5+) intestinal stem cells (ISCs). It has been postulated, however, that slowly cycling ISCs must also be present in the intestine to protect the genome from accumulating deleterious mutations and to allow for a response to tissue injury. Here, we identify a subpopulation of slowly cycling ISCs marked by mouse telomerase reverse transcriptase (mTert) expression that can give rise to Lgr5+ cells. mTert-expressing cells distribute in a pattern along the crypt–villus axis similar to long-term label-retaining cells (LRCs) and are resistant to tissue injury. Lineage-tracing studies demonstrate that mTert+ cells give rise to all differentiated intestinal cell types, persist long term, and contribute to the regenerative response following injury. Consistent with other highly regenerative tissues, our results demonstrate that a slowly cycling stem cell population exists within the intestine

CureGN Study Rationale, Design, and Methods: Establishing a Large Prospective Observational Study of Glomerular Disease

Glomerular diseases, including minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and immunoglobulin A (IgA) nephropathy, share clinical presentations, yet result from multiple biological mechanisms. Challenges to identifying underlying mechanisms, biomarkers, and new therapies include the rarity of each diagnosis and slow progression, often requiring decades to measure the effectiveness of interventions to prevent end-stage kidney disease (ESKD) or death. Multicenter prospective cohort study. Cure Glomerulonephropathy (CureGN) will enroll 2,400 children and adults with minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy (including IgA vasculitis) and a first diagnostic kidney biopsy within 5 years. Patients with ESKD and those with secondary causes of glomerular disease are excluded. Clinical data, including medical history, medications, family history, and patient-reported outcomes, are obtained, along with a digital archive of kidney biopsy images and blood and urine specimens at study visits aligned with clinical care 1 to 4 times per year. Patients are followed up for changes in estimated glomerular filtration rate, disease activity, ESKD, and death and for nonrenal complications of disease and treatment, including infection, malignancy, cardiovascular, and thromboembolic events. The study design supports multiple longitudinal analyses leveraging the diverse data domains of CureGN and its ancillary program. At 2,400 patients and an average of 2 years’ initial follow-up, CureGN has 80% power to detect an HR of 1.4 to 1.9 for proteinuria remission and a mean difference of 2.1 to 3.0mL/min/1.73m2 in estimated glomerular filtration rate per year. Current follow-up can only detect large differences in ESKD and death outcomes. Study infrastructure will support a broad range of scientific approaches to identify mechanistically distinct subgroups, identify accurate biomarkers of disease activity and progression, delineate disease-specific treatment targets, and inform future therapeutic trials. CureGN is expected to be among the largest prospective studies of children and adults with glomerular disease, with a broad goal to lessen disease burden and improve outcomes

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

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 to similar associations with COVID-19 vaccination. Observational cohort study from July 1, 2021 to Jan. 1, 2023. & 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. COVID-19 and COVID-19 vaccination. Repeated measure of estimated glomerular filtration rate (eGFR); recurrent time-to-event outcome of GN disease worsening as defined by doubling of UPCR to at least 1.5g/g or increase in dipstick urine protein by two ordinal levels to 3+ (300mg/dL) or above. Interrupted time series analysis for eGFR. Prognostic matched sequential stratification recurrent event analysis for GN disease worsening. Among 2,055 participants, 722 (35%) reported COVID-19; of these, 92 (13%) were hospitalized and 3 died (<1%). eGFR slope pre-COVID-19 was -1.40ml/min/1.73m2 (SD 0.29), and -4.26ml/min/1.73m2 (SD 3.02) within 6 months post-COVID-19, which were 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 change in eGFR (-1.34ml/min/1.73m2, SD 0.15 vs -2.16ml/min/1.73m2, SD 1.74; p=0.6) or subsequent GN disease worsening (HR 1.02, 95% CI 0.79–1.33) in this cohort. Infrequent or short follow-up. Among patients with primary GN, COVID-19 was severe for 1 in 8 cases and was associated with subsequent worsening of GN disease activity, as defined by proteinuria. In 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. 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. In contrast, vaccination did not appear to adversely affect kidney function or proteinuria. Our data support vaccination for COVID-19 in patients with glomerular disease