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Background: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are characterized by small vessel inflammation, often associated with proteinase 3 or myeloperoxidase-ANCAs. Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) represent 80-90% of cases [1,2]. Renal involvement, commonly presenting as relapsing-remitting pauci-immune necrotizing and crescentic glomerulonephritis, significantly contributes to morbidity and risk of end-stage renal failure, necessitating prompt detection and management. Renal biopsy remains the gold standard for evaluating renal involvement and activity [3]. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression post-transcriptionally and are stable in tissues and body fluids, making them potential biomarkers for autoimmune diseases [4]. Only two studies have explored miRNA expression in AAV: one focused on pooled renal biopsies [5] and the other on urinary extracellular vesicles [6]. In comparison, lupus nephritis (LN) is the most extensively studied immune-mediated kidney disease [7]. Investigating miRNA deregulation in the kidney could enhance understanding of AAV pathogenesis and aid in identifying biomarkers of disease activity.
To identify differentially expressed miRNAs in kidney biopsies from AAV patients compared to controls.
To identify miRNAs in kidney biopsies that distinguish MPA patients from GPA patients.
To hypothesize the biological roles of the identified miRNAs.
Methods: Total RNA was extracted and purified from formalin-fixed paraffin-embedded renal biopsies (8 MPA, 8 GPA and 8 controls without inflammation). A panel of 798 miRNAs (NS_H_MIR_V3B panel) was profiled using NanoString nCounter technology. The threshold was fixed at 30 counts and 12 miRNAs were used for data normalization. Fisher exact test was used to evaluate the presence or absence of miRNAs. Mann Whitney U test and Kruskall Wallis test were used to compare miRNA levels between and among groups. P-values were adjusted using the Benjamini-Yekutieli method. MiRNAs identified in the discovery step underwent a validation step in renal biopsies from 9 MPA, 9 GPA, 9 LN patients and 9 controls using real-time PCR with miRNA-optimized LNA Technology. miR-191-5p was used as reference miRNA. The in silico identification of the genes targeted by the validated miRNAs was performed by using miRTarbase which collects experimentally validated microRNA–target interactions. Only those targets identified with a strong evidence (luciferase assays and/or western blot experiments) were considered. The pathway enrichment analysis was performed by using the EnrichR web tool.
Results: Nanostring nCounter profiling showed that miR-10b-5p, miR-30a-5p, miR-30d-5p, miR-99a-5p, miR-4286 were down-regulated, while miR-1285-5p was up-regulated in AAV compared to controls (at least 2-fold change in miRNA expression, adjusted p values < 0.01). MiR-22-3p and miR-204-5p were present in all controls but absent in 13/16 AAV cases. Validation by real-time PCR in renal biopsies (9 MPA, 9 GPA, 9 LN patients and 9 controls) confirmed that miR-10b-5p, -30a-5p, -30d-5p, -99a-5p, -204-5p were down-regulated, while miR-1285-5p was up-regulated in AAV versus controls. Additionally, miR-30d-5p, -99a-5p, -204-5p were down-regulated in AAV compared to LN. No differences in miRNA expression were found between MPA and GPA. In silico analysis revealed that miR-10b-5p, miR-30a-5p, and miR-30d-5p commonly target NOTCH1 and TP53. Moreover, miR-30a-5p, miR-30d-5p and miR-204-5p commonly target RUNX2 and SNAI1. Notably, P53 and SNAI1 are implicated in renal fibrosis progression, promoting extracellular matrix deposition, G2/M cell cycle arrest, and inflammation [8]. MiR-1285-5p has no strongly validated targets. Pathway enrichment analysis showed that the 4 commonly targeted genes regulate PTEN gene transcription. PTEN plays a critical role in cell proliferation, apoptosis, autophagy, fibrosis, and mitochondrial energy metabolism during the progression from acute kidney injury to chronic kidney disease [9].
Conclusion: We identify a signature of 6 miRNAs (MiR-10b-5p, -30a-5p, -30d-5p, -99a-5p, -204-5p, -1285-5p) deregulated in renal tissue of AAV patients compared to controls. Functional studies are needed to clarify their roles in the kidney and explore their potential as therapeutic targets. Future analysis of these miRNAs in urine samples may determine their value as non-invasive biomarkers for disease activity.
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Acknowledgements: Fondazione Cariparma, Parma, Italy for partly supporting the project.
Disclosure of Interests: None declared.
© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license (