DS0403 - Exploration des systèmes et organes leur fonctionnement normal et pathologique : physiologie, physiopathologie, vieillissement

Micro-RNAs of neutrophils in renal ANCA-associated vasculitis – MINERVA

Submission summary

Activation of neutrophils by ANCA (“Anti-Neutrophil Cytoplasm Antibodies”) and subsequent microvascular endothelial cell damage is the main feature of ANCA-associated vasculitis (AAV), a severe autoimmune disease that often targets the kidney. There is no specific treatment for AAV to date and 25% of patients with renal damage evolve towards end-stage renal disease, requiring dialysis and kidney transplantation. In addition, there is no reliable biological marker of the disease activity available, which makes the diagnostic, follow-up and treatment of patients difficult. Therefore, the identification of new therapeutic targets and non-invasive biomarkers constitutes a major clinical challenge to improve AAV patients care and to ameliorate their renal outcome.
Micro-RNAs (miRNA) are well established as critical regulators of major biological responses in various cell types including endothelial cells (EC) and neutrophils, and accumulating data indicate that they are involved in the pathophysiology of many diseases, including autoimmune diseases. In addition, miRNAs are actively secreted by cells within microparticles (exosomes and shed extracellular microvesicles) and are thus detected in the circulation and other biological fluids, where their expression is unusually stable, as their packaging inside microparticles protects them from RNase-mediated degradation. Therefore, secreted miRNAs have been proposed as promising non-invasive biomarkers for a variety of human pathologies. Besides, accumulating data indicate that secreted miRNAs actively participate to intercellular crosstalks in various physiological and pathological situations. Indeed, miRNAs released by a cell within microparticles can be transferred to another “recipient” cell, where they function to regulate target genes and subsequent biological responses. Recent studies have shown that neutrophils release microparticles with immunoregulatory functions, and that microparticles released by neutrophils upon ANCA stimulation induce EC activation and damage. This strongly suggests a pathogenic role for neutrophil-derived microparticles in the development of vascular endothelial lesions during AAV. However, the mechanisms by which these microparticles can induce EC damage and the pathophysiological role of miRNAs they may contain are still completely unknown. More generally, there is still very little data available about the expression and function of miRNAs in association with AAV.
In this project, we propose to identify miRNAs deregulated in ANCA-activated neutrophils and released in the circulation within microparticles, which participate in the development of EC activation and damage over the course of AAV. These miRNAs will be identified using TaqMan Low Density Arrays (TLDA) in ANCA-stimulated neutrophils in vitro and in the microparticles they release. To validate in vitro results and to assess whether these miRNAs could be used as biomarkers, their expression will also be analyzed in neutrophils, plasma and urine samples from AAV patients at various time points over the course of the disease (acute inflammatory phase, remission, relapse), and correlated with the activity and the severity of the disease (Task 1). The transfer of miRNAs secreted by ANCA-activated neutrophils to EC will be assessed in vitro, and the potential role of the complement pathway in this transfer will be analyzed (Task 2). Finally, the function of these miRNAs in the regulation of EC responses (activation, angiogenesis) will be studied in various functional assays (Task 3).
While miRNAs are emerging as new therapeutic tools and biomarkers for several diseases, this translational study will provide the first data regarding the expression and function of neutrophil miRNAs in AAV and may therefore pave the way for novel promising miRNA-targeted therapeutic options in these patients.

Project coordination

Sarah Bruneau (Centre de Recherche en Transplantation et Immunologie)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Centre de Recherche en Transplantation et Immunologie

Help of the ANR 273,973 euros
Beginning and duration of the scientific project: September 2015 - 42 Months

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