Clinicopathological Analysis of 34 Cases of Primary Antineutrophil Cytoplasmic Antibody-Associated Vasculitis in Chinese Children

Performance of EMA algorithm, 2022 ACR/EULAR criteria, and EMA-ACR/EULAR algorithm in classifying pediatric ANCA-associated vasculitis: a national cohort study in China

BACKGROUND

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) is a type of necrotizing vasculitis with poor prognosis, which is more severe in children. Classifying AAV patients may be helpful for diagnosis and management. However, present classification criteria for pediatric AAV are developed mainly based on adults, which have limitations in clinical practice. In this study, we introduced an updated algorithm based on the European Medicines Agency (EMA) algorithm in conjunction with the American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) criteria. This new approach aims to resolve the issue of duplicate classification present in the 2022 ACR/EULAR criteria and to refine the existing EMA algorithm.

METHODS

This study included 179 pediatric patients diagnosed with AAV across 17 centers in China. Patients were classified using the EMA algorithm, the ACR/EULAR criteria, and the EMA-ACR/EULAR algorithm. The Kappa value and Net Reclassification Index (NRI) were used to evaluate the classification performance of these criteria.

RESULTS

According to the EMA algorithm, 136 (76.0%) patients were classified with microscopic polyangiitis (MPA) and 14 (7.8%) with granulomatosis with polyangiitis (GPA), while 29 (16.2%) remained unclassifiable. According to the ACR/EULAR criteria, 145 (81.0%) patients were classified with MPA, 14 (7.8%) with GPA, 2 (1.1%) with eosinophilic granulomatosis with polyangiitis (EGPA), and 4 (2.2%) with both MPA and GPA, while 14 (7.8%) remained unclassifiable. The EMA-ACR/EULAR algorithm classified 124 patients (69.3%) as MPA, 26 (14.5%) as GPA, and 2 (1.1%) as EGPA, while 27 (15.1%) were unclassified. The Kappa values between the EMA algorithm and ACR/EULAR criteria for GPA and MPA were 0.225 [95% confidence interval (CI) 0.000-0.456, P = 0.003] and 0.357 (95% CI 0.196-0.518, P < 0.001). Compared to these two criteria, the EMA-ACR/EULAR algorithm demonstrated positive NRIs in the classification of both GPA (0.702, 95% CI 0.258-1.146, P = 0.002; 0.547 95% CI 0.150-0.944, P = 0.007) and MPA (0.425, 95% CI 0.209-0.642, P < 0.001; 0.519, 95% CI 0.305-0.733, P < 0.001).

CONCLUSIONS

The EMA-ACR/EULAR algorithm addresses the limitations of the 1990 ACR criteria within the EMA framework and resolves the issue of duplicate classification in the 2022 ACR/EULAR criteria. However, further research is necessary to validate the superiority of the EMA-ACR/EULAR algorithm in the clinical classification of pediatric AAV patients.

Comparison of the clinicopathological characteristics of children with anti-neutrophil cytoplasmic antibody-associated vasculitis with/without infection at diagnosis

BACKGROUND

Infectious episodes contribute to morbidity and mortality in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Renal involvement, also known as ANCA-associated glomerulonephritis (AGN), is frequently observed in AAV. Little is known about whether co-infection at initial diagnosis is associated with renal outcome and prognosis in children with AGN.

METHODS

Clinical and prognostic data for children admitted to our center with AAV from January 2001 to August 2023 were analyzed retrospectively. We compared the incidence of end-stage renal disease (ESRD) and mortality according to infection status at initial diagnosis.

RESULTS

A total of 33 children with AGN were included in this study, 22 had an infection at the time of AGN diagnosis. A trend toward higher levels of proteinuria in the infected group than in the non-infected group was observed (p = 0.42). Patients in the infected group had higher creatinine and lower eGFR values than those in the non-infected group (p = 0.09). A significant decrease in HGB was observed in the infected group (p < 0.05). There were no significant differences in the baseline values of ALB and complement c3 between the two groups. A similar proportion of patients in both groups required dialysis at the time of diagnosis (27.3% vs. 31.8%). Patients with infection presented with significantly greater ESR and CRP levels (p < 0.05), and the most commonly infected site was the lung. After 6 months of treatment, compared with those in the non-infected group, the median levels of creatinine and proteinuria were higher in the infected group. Besides, lower levels of eGFR and ALB were also observed in the infected group. 5 (45.5%) and 13 (59.1%) patients died or progressed to ESRD, respectively, in the non-infected group and infected group at the last follow-up.

CONCLUSIONS

Infection at initial diagnosis does not affect the outcomes of children with AGN, although it could lead to a reduction in kidney function.

Update on antineutrophil cytoplasmic autoantibody vasculitis in children

PURPOSE OF REVIEW

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is often organ- or life-threatening in children and impacts them during important periods of psychosocial and physical development. This review covers recent advances in the pathophysiology, diagnosis, management, and outcomes of AAV in children and highlights the ongoing need for funding and increased research collaboration.

RECENT FINDINGS

Recent work has improved our understanding of AAV disease pathogenesis, potentially identifying new biomarkers and therapeutic targets. Collaborative clinical studies have also highlighted the variable manifestations in children and identified potential factors associated with poorer outcomes. Consensus-based treatment guidelines are also appearing, but clinical trials are still essential to better understanding treatment efficacy and safety in children affected by AAV. New, validated outcome measures, including those that are patient-reported, will facilitate these much-needed clinical trials in pediatric AAV.

SUMMARY

There is a continued need for more rigorous study in pediatric AAV, however, there is certainly excitement with the increase in recent research relevant to the pediatric population.

Risk factors for renal outcomes in children with antineutrophil cytoplasmic antibody-associated vasculitis: a nationwide retrospective study in China

BACKGROUND

Pediatric antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a life-threatening systemic vasculitis featured by liability to renal involvement. However, there are few studies on the risk factors and predictive models for renal outcomes of AAV in children.

METHODS

Data from 179 AAV children in multiple centers between January 2012 and March 2020 were collected retrospectively. The risk factors and predictive model of end-stage renal disease (ESRD) in AAV were explored.

RESULTS

Renal involvement was the most typical manifestation (95.5%), and the crescent was the predominant pathological lesion (84.9%). The estimated glomerular filtration rate (eGFR) was evaluated in 114 patients, of whom 59.6% developed ESRD, and the median time to ESRD was 3.20 months. The eGFR [P = 0.006, odds ratio (OR) = 0.955, 95% confidence interval (CI) = 0.924-0.987] and the percentages of global glomerulosclerosis (pGGS; P = 0.018, OR = 1.060, 95% CI = 1.010-1.112) were independent risk factors for ESRD of renal biopsy. Based on the pGGS and eGFR at renal biopsy, we developed three risk grades of ESRD and one predictive model. The Kaplan‒Meier curve indicated that renal outcomes were significantly different in different risk grades (P < 0.001). Compared with serum creatinine at baseline, the predictive model had higher accuracy (0.86 versus 0.58, P < 0.001) and a lower coefficient of variation (0.07 versus 0.92) in external validation.

CONCLUSIONS

Renal involvement is the most common manifestation of pediatric AAV in China, of which more than half deteriorates into ESRD. The predictive model based on eGFR at renal biopsy and the pGGS may be stable and accurate in speculating the risk of ESRD in AAV children. Supplementary file 2 (MP4 18937 KB).

Identification of new immune subtypes of renal injury associated with anti-neutrophil cytoplasmic antibody-associated vasculitis based on integrated bioinformatics analysis

Background: Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a systemic autoimmune disease that may lead to end-stage renal disease. However, few specifific biomarkers are available for AAV-related renal injury. The aim of this study was to identify important biomarkers and explore new immune subtypes of AAV-related renal injury. Methods: In this study, messenger RNA expression profiles for antibody-associated vasculitis and AAV-associated kidney injury were downloaded from the Gene Expression Omnibus database. Weighted gene co-expression network analysis (WGCNA) was performed to identify the most relevant module genes to AAV. Key module genes from WGCNA were then intersected with AAV- and nephropathy-related genes from the Genecards database to identify key genes for AAV-associated kidney injury. Subsequently, the expression of key genes was validated in independent datasets and the correlation of genes with clinical traits of kidney injury was verified by the Nephroseq database. Finally, non-negative matrix factorization (NMF) clustering was performed to identify the immune subtypes associated with the key genes. Results: Eight co-key genes (AGTR2, ANPTL2, BDKRB1, CSF2, FGA, IL1RAPL2, PCDH11Y, and PGR) were identifified, and validated the expression levels independent datasets. Receiver operating characteristic curve analysis revealed that these eight genes have major diagnostic value as potential biomarkers of AAV-related renal injury. Through our comprehensive gene enrichment analyses, we found that they are associated with immune-related pathways. NMF clustering of key genes identified two and three immune-related molecular subtypes in the glomerular and tubular data, respectively. A correlation analysis with prognostic data from the Nephroseq database indicated that the expression of co-key genes was positively co-related with the glomerular filtration rate. Discussion: Altogether, we identifified 8 valuable biomarkers that firmly correlate with the diagnosis and prognosis of AAV-related renal injury. These markers may help identify new immune subtypes for AAV-related renal injury.

Clinical and Renal Histology Findings and Different Responses to Induction Treatment Affecting the Long-Term Renal Outcomes of Children With ANCA-Associated Vasculitis: a Single-Center Cohort Analysis

Introduction

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is relatively rare in children. This article aimed to analyze clinical and renal histology findings and different responses to induction treatment associated with the long-term renal outcomes in children with AAV in a single center.

Methods

All pediatric patients with AAV admitted to Tongji Hospital from January 2002 to January 2021 were included in the study. The demographic, clinical, pathological, laboratory, and treatment data and outcomes were collected and analyzed to identify predictors associated with response to induction treatment and progression to end-stage renal disease (ESRD).

Results

In total, 48 children with AAV were included in this cohort; 81.25% of them were women, and 91.7% were microscopic polyangiitis (MPA). Kidney involvement was found in 45 patients (93.75%). The most common histopathological subtype was crescentic form in this cohort according to Berden's classification. In total, 34 patients (70.8%) showed eGFR <60 ml/min/1.73 m2 at the time of diagnosis. Complete and partial remission was achieved in 8 patients (16.7%) and 19 patients (39.6%), respectively, following 6-month induction treatment. Half of the patients eventually progressed to ESRD at a mean time of (13.04 ± 15.83) months after diagnosis. The independent predictors of nonremission following induction treatment and progression to ESRD were baseline eGFR <60 ml/min/1.73 m2 and hypertension at diagnosis. Renal survival significantly decreased over time in patients with renal sclerotic subtypes or those with nonremission following induction treatment by Kaplan-Meier curve estimation.

Conclusions

Our study demonstrates that women, MPA, and crescentic subtypes are predominant in pediatric AAV in China. Initial renal failure (eGFR <60 ml/min/1.73 m2), hypertension, sclerotic pathological subtype, and nonremission following induction treatment are predictive of long-term renal outcomes.

Identification of differentially expressed genes and pathways in kidney of ANCA-associated vasculitis by integrated bioinformatics analysis

The antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a systematic of relatively rare autoimmune diseases with unknown cause. Kidney involvement is one of the most common clinical manifestations, and the degree of renal damage is closely associated with the development and prognosis of AAV. In this study, we utilized the Robust Rank Aggreg (RRA) method in R to integrate GSE104948, GSE104954, GSE108109, GSE108112, and GSE108113 profile datasets loaded from Gene Expression Omnibus (GEO) database and identified a set of differentially expressed genes (DEGs) in kidney between AAV patients and living donors. Then, the results of gene ontology (GO) functional annotation showed that immunity and metabolism involved process of AAV both in glomerulus and tubulointerstitial. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that following pathways, such as complement and coagulation cascades pathway; Staphylococcus aureus infection; disease-COVID-19; and systemic lupus erythematosus (SLE) pathway play a crucial role in AAV. Next, the results analyzed by protein–protein interaction (PPI) network and Cytoscape software exhibited the hub genes ALB, TYROBP, and CYBB existed in both glomerular and tubulointerstitial compartments datasets. Finally, KEGG analysis using genes of two most important modules also further validated complement and coagulation cascades pathway and S. aureus infection existed both in glomerulus and tubulointerstitial compartments datasets. In conclusion, this study identified key genes and pathways involved in kidney of AAV, which was benefit to further uncover the mechanisms underlying the development and progress of AAV, biomarkers, and potential therapeutic targets as well.

Clinical features and outcomes of anti-neutrophil cytoplasmic autoantibody-associated vasculitis in Chinese childhood-onset patients

Data on anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) are limited in children. This study is to determine the clinical features and outcomes of childhood-onset AAV. A retrospective study was performed on patients who were diagnosed with AAV before 18 years old in Xiangya Hospital. Their medical records were analyzed by retrospective review. Sixteen patients were diagnosed with AAV before 18 years old in the past 9 years, with an average age of 13.3 ± 3.3 years and 13 of them were female. There were 15 patients with microscopic polyangiitis (MPA) and 1 with Wegener's granulomatosis. The interval between onset of disease and diagnosis of AAV was 2 (1.5-3) months. Most patients (15/16, 93.8%) had multi-organ involvement, and all patients had renal involvement with 7 (43.8%) patients requiring dialysis at presentation. Eleven patients underwent a renal biopsy, of which mixed class and sclerotic class were the most two common histological types. All patients received immunosuppressive therapy for induction therapy including intravenous administrations of methylprednisolone (MP) pulse therapy for 8 patients. 8 patients (50%) achieved remission after induction therapy. After a median follow-up of 46.3 ± 36.1 months, nine (56.3%) patients progressed to end-stage renal disease (ESRD) and 5 (31.3%) patients died. Childhood-onset AAV showed similar clinical and pathological features compared to those of adults, except that it usually occurs in girls. The most commonly involved organ was the kidney, and it had a high risk of progression to ESRD. Early diagnosis and initiation of appropriate immunomodulatory therapy would be important to improve outcomes.