Increased incidence and improved prognosis of glomerulonephritis: a national 30-year study

Years of life lost and long-term outcomes due to glomerular disease in a Southeast Asian Cohort

Death and end-stage kidney disease (ESKD) are major outcomes of glomerular disease. (GD) The years of potential life lost (YLL) may provide additional insight into the disease burden beyond death rates. There is limited data on premature mortality in GD. In this retrospective observational cohort study, we evaluated the mortality, ESKD rates, and YLL in Thais with biopsy-proven GD. The mortality and combined outcome rates were determined by log-rank test and ESKD by using a competing risk model. YLL and premature life lost before age 60 were calculated for different GD based on the life expectancy of the Thai population. Patients with GD (n = 949) were followed for 5237 patient years. The death rate and ESKD rates (95%CI) were 4.2 (3.7-4.9) and 3.3 (2.9-3.9) per 100 patient-years, respectively. Paraprotein-related kidney disease had the highest death rate, and diabetic nephropathy had the highest ESKD rate. Despite not having the highest death rate, lupus nephritis (LN) had the highest YLL (41% of all GD) and premature loss of life before age 60. In conclusion, YLL provided a different disease burden assessment compared to mortality rates and identified LN as the major cause of premature death due to GD in a Southeast Asian cohort.

Focal Segmental Glomerulosclerosis: Assessing the Risk of Relapse

Introduction

Kidney outcomes are improved in primary focal segmental glomerulosclerosis (FSGS) by maintaining a remission in proteinuria. However, characteristics associated with relapses are uncertain. We sought to identify these by analyzing each remission.

Methods

We performed a retrospective study in patients with biopsy-proven lesions of FSGS, absent identifiable secondary cause, who had at least 1 remission from nephrotic-range proteinuria. In each patient, we identified every remission, every relapse, and their durations. Using a multilevel logistic regression to account for the clustering of multiple remissions within a patient, we tested which clinical characteristics were independently associated with relapses.

Results

In 203 individuals, 312 remissions occurred, 177 with and 135 without relapse. A minority of remissions were atypical, defined by either absent hypoalbuminemia and/or no immunosuppression (IS), in contrast to the classic nephrotic syndrome that remits with IS. Atypical remission variants were just as likely to relapse as the classical presentation. Only 24% of remission events were on maintenance therapy at relapse. Independent characteristics associated with relapses were higher maximal proteinuria while nephrotic; and in remission, higher nadir proteinuria, lower serum albumin, and higher blood pressure. Using these variables, we created a tool estimating the 1-year risk of relapse ranging from 9% to 80%, well-calibrated to the observed data.

Conclusion

In FSGS, relapses are frequent but predictable using independent clinical characteristics. We also provide evidence that atypical presentations remit and relapse following the same pattern as classic FSGS presentations. Treatment strategies to prolong remission duration should be addressed in future trials.

New insights into epidemiological data and impact of the COVID-19 pandemic on IgA vasculitis in children and adults: a French nationwide cohort

IgA vasculitis (IgAV) is a small size vasculitis for which epidemiologic data are strikingly lacking, especially about the adult form. Additionally, the COVID-19 pandemic seems to have profoundly modified the incidence of this disease. Here, we aimed to establish some relevant epidemiological data in both pediatric and adult IgAV. We performed an observational study using a national database called "BNDMR" on IgAV, which gathers patients managed in the French network of experts on rare diseases. We primarily performed descriptive statistics over the 2010-2022 period. Then, we compared the North-South geographical areas, the seasonality, and the impact of COVID-19 with that of other patients reported in the same centers. We collected data from 1988 IgAV patients. The sex ratio was 1.57 for adults and 1.05 for children. The annual incidence in 2021 was 0.06 for 100,000 adults and 0.50 for 100,000 children. Compared with other diseases reported into the BNDMR, IgAV was more common in the South than in the North of France (OR 4.88 [4.17-5.74] in adults and OR 1.51 [1.35-1.68] in children). IgAV was also observed more frequently in winter and autumn. Strikingly, we observed a decrease in incidence during the COVID-19 pandemic period in children (OR 0.62 [0.47-0.81]). Our study provides both new insights and confirmations of IgAV epidemiological data: winter and autumn seasonality, more pronounced male predominance in adults, decreasing incidence of pediatric IgAV during the COVID-19 pandemic and increasing incidence in the South of France.

Glomerulonephritis and inflammatory bowel disease: A tale of gut-kidney axis dysfunction

The incidence and prevalence of Inflammatory Bowel Disease (IBD) has increased over the past decades, imposing a growing socioeconomic burden on healthcare systems globally. Most of the morbidity and mortality related to IBD is typically attributed to gut inflammation and its complications; yet the disease is characterized by various extraintestinal manifestations that can be severe. Glomerulonephritis (GN) is of particular interest since a significant proportion of patients evolve into end-stage kidney disease, requiring kidney replacement therapy and associated with high morbidity and mortality. Herein, we review the GN landscape in IBD and define the clinical and pathogenic associations reported to date in the literature. Underlying pathogenic mechanisms suggest either the initiation of antigen-specific immune responses in the inflamed gut that cross react with non-intestinal sites, such as the glomerulus, or that extraintestinal manifestations are gut-independent events that occur due to an interaction between common genetic and environmental risk factors. We present data associating GN with IBD either as a bona fide extraintestinal manifestation or reporting it as an extraneous co-existing entity, involving various histological subtypes, such as focal segmental glomerulosclerosis, proliferative GN, minimal change disease, crescentic GN, but most emphatically IgA nephropathy. Supporting the pathogenic interplay between gut inflammation and intrinsic glomerular processes, enteric targeting the intestinal mucosa with budesonide reduced IgA nephropathy-mediated proteinuria. Elucidating the mechanisms at play would provide insight not only into IBD pathogenesis but also into the gut's role in the development of extraintestinal diseases, such as glomerular diseases.

Identification of Unique Genetic Biomarkers of Various Subtypes of Glomerulonephritis Using Machine Learning and Deep Learning

(1) Objective: Identification of potential genetic biomarkers for various glomerulonephritis (GN) subtypes and discovering the molecular mechanisms of GN. (2) Methods: four microarray datasets of GN were downloaded from Gene Expression Omnibus (GEO) database and merged to obtain the gene expression profiles of eight GN subtypes. Then, differentially expressed immune-related genes (DIRGs) were identified to explore the molecular mechanisms of GN, and single-sample gene set enrichment analysis (ssGSEA) was performed to discover the abnormal inflammation in GN. In addition, a nomogram model was generated using the R package "glmnet", and the calibration curve was plotted to evaluate the predictive power of the nomogram model. Finally, deep learning (DL) based on a multilayer perceptron (MLP) network was performed to explore the characteristic genes for GN. (3) Results: we screened out 274 common up-regulated or down-regulated DIRGs in the glomeruli and tubulointerstitium. These DIRGs are mainly involved in T-cell differentiation, the RAS signaling pathway, and the MAPK signaling pathway. ssGSEA indicates that there is a significant increase in DC (dendritic cells) and macrophages, and a significant decrease in neutrophils and NKT cells in glomeruli, while monocytes and NK cells are increased in tubulointerstitium. A nomogram model was constructed to predict GN based on 7 DIRGs, and 20 DIRGs of each subtype of GN in glomeruli and tubulointerstitium were selected as characteristic genes. (4) Conclusions: this study reveals that the DIRGs are closely related to the pathogenesis of GN and could serve as genetic biomarkers in GN. DL further identified the characteristic genes that are essential to define the pathogenesis of GN and develop targeted therapies for eight GN subtypes.

Quantifying the benefits of remission duration in focal and segmental glomerulosclerosis

BACKGROUND

Although the clinical benefit of obtaining a remission in proteinuria in nephrotic patients with focal and segmental glomerulosclerosis (FSGS) is recognized, the long-term value of maintaining it and the impact of relapses on outcome are not well described.

METHODS

We examined the impact of remissions and relapses on either a 50% decline in kidney function or ESKD (combined event) using time-dependent and landmark analyses in a retrospective study of all patients from the Toronto Glomerulonephritis Registry with biopsy-proven FSGS, established nephrotic-range proteinuria and at least one remission.

RESULTS

In the 203 FSGS individuals with a remission, 89 never relapsed and 114 experienced at least one relapse. The first recurrence was often followed by a repeating pattern of remission and relapse. The 10-year survival from a combined event was 15% higher in those with no relapse versus those with any relapse. This smaller than anticipated difference was related to the favorable outcome in individuals whose relapses quickly remitted. Relapsers who ultimately ended in remission (n = 46) versus in relapse (n = 68) experienced a 91% and 32% 7-year event survival (p<0.001). Using time-varying survival analyses that considered all periods of remission and relapse in every patient and adjusting for each period's initial eGFR, the state of relapse was associated with a 2.17 (95%CI,1.32-3.58, p = 0.002) greater risk of experiencing a combined event even in this FSGS remission cohort.

CONCLUSIONS

In FSGS, unless remissions are maintained and relapses avoided, long-term renal survival remains poor. Treatment strategies addressing remission duration remain poorly defined and should be an essential question in future trials.

Epidemiology of native kidney disease in Flanders: results from the FCGG kidney biopsy registry

Background

The Flemish Collaborative Glomerulonephritis Group (FCGG) registry is the first population-based native kidney biopsy registry in Flanders, Belgium. In this first analysis, we report on patient demographics, frequency distribution and incidence rate of biopsied kidney disease in adults in Flanders.

Methods

From January 2017 to December 2019, a total of 2054 adult first native kidney biopsies were included. A ‘double diagnostic coding’ strategy was used, in which every biopsy sample received a histopathological and final clinical diagnosis. Frequency distribution and incidence rate of both diagnoses were reported and compared with other European registries.

Results

The median age at biopsy was 61.1 years (interquartile range, 46.1–71.7); male patients were more prevalent (62.1%) and biopsy incidence rate was 129.3 per million persons per year. Immunoglobulin A nephropathy was the most frequently diagnosed kidney disease (355 biopsies, 17.3% of total) with a similar frequency as in previously published European registries. The frequency of tubulointerstitial nephritis (220 biopsies, 10.7%) and diabetic kidney disease (154 biopsies, 7.5%) was remarkably higher, which may be attributed to changes in disease incidence as well as biopsy practices. Discordances between histopathological and final clinical diagnoses were noted and indicate areas for improvement in diagnostic coding systems.

Conclusions

The FCGG registry, with its ‘double diagnostic coding’ strategy, provides useful population-based epidemiological data on a large Western European population and allows subgroup selection for future research.

Characteristics and outcomes of glomerulonephritis with membranoproliferative pattern in children

BACKGROUND

Membranoproliferative glomerulonephritis (MPGN) is a rare histopathologic pattern of glomerular injury with limited studies in pediatric patients. Characteristics and outcomes of children with MPGN have also remained to be further explored.

METHODS

We retrospectively reviewed the clinicopathological features, genetic findings, treatments and outcomes in 17 pediatric patients pathologically diagnosed with MPGN from 2007 to 2020 in the Children's National Medical Center in China.

RESULTS

Median age at disease onset was 9.9 years (IQR, 5.6-11.9 years). Most of the patients (12/17) had nephrotic range of proteinuria, and nephritic-nephrotic syndrome was the most common clinical presentation (35.2%). Secondary causes were identified in eight patients including hepatitis B virus (HBV) infection (n=4), methylmalonic acidemia (MMA, n=2), rheumatoid arthritis (RA, n=1) and Aymé-Gripp Syndrome (n=1). The nine patients with primary MPGN were further identified as immune-complex mediated MPGN (n=8), and unclassifiable MPGN (U-MGPN, n=1). Genetic analyses identified pathogenic variants of MMACHC gene in two cases of MMA and established the diagnosis for Aymé-Gripp syndrome in one case with a de novo variant of MAF gene. Comparing study between the complete or partial remission group (n=8) and non-response group (n=9) showed a significant difference in the timing of renal biopsy (P<0.05). Normal renal function was preserved in ten patients at the last follow-up. Two patients developed into end-stage renal disease (ESRD).

CONCLUSIONS

Children with MPGN pattern present heterogenous clinical features. Genetic detection helps to explore underlying causes of MPGN. Early identification of the primary or secondary causes of MPGN in children is vital.

Course monitoring of membranous nephropathy: Both autoantibodies and podocytes require multidimensional attention

A variety of podocyte antigens have been identified in human membranous nephropathy (MN), which is divided into various antigen-dominated subtypes, confirming the concept that MN is the common pattern of glomerular injury in multiple autoimmune responses. The detection of autoantibodies has been widely used, which promoted the clinical practice of MN toward personalized precision medicine. However, given the potential risks of immunosuppressive therapy, more autoantibodies and biomarkers need to be identified to predict the prognosis and therapeutic response of MN more accurately. In this review, we attempted to summarize the autoantigens/autoantibodies and autoimmune mechanisms that can predict disease states based on the current understanding of MN pathogenesis, especially the podocyte injury manifestations. In conclusion, both the autoimmune response and podocyte injury require multidimensional attention in the disease course of MN.