Extracellular vesicle‐derived microRNAs as potential biomarkers in oligoarticular juvenile idiopathic arthritis patients: methodological challenges and new perspectives

This is the authors' abstract. We don't add key points for this paper.

Dear Editor, Oligoarticular juvenile idiopathic arthritis (OJIA) is the most common chronic paediatric arthritis in Western countries and a major cause of childhood disability.1 Early diagnosis and prediction of disease course and therapeutic response are crucial for patient management but are hindered by the lack of biomarkers. Identification of new low-invasive biomarkers is thus highly required to improve the current diagnosis of OJIA patients and help with the setting up of targeted treatments at disease onset, which would allow to reduce the burden of the disease, limit the occurrence of joint damage and loss of functionality, minimize patient exposure to the potential side-effects of ineffective medication, and induce earlier remission, thus enhancing patient quality of life2 (Supporting Information, Section 1). Extracellular vesicles (EVs) released into biologic fluids have gained increased recognition as key mediators of the pathogenesis of many chronic inflammatory and autoimmune diseases, including adult arthritides,3 and as a reliable and enriched source of disease biomarkers, by virtue of their cargo of bioactive molecules (nucleic acids, proteins, and lipids) of cellular origin, which can be transferred to, and elicit responses in, recipient cells.4 Analysis of microRNAs encapsulated in EVs (EV-miRs) provides a powerful means for new noninvasive biomarker discovery, given their high stability, concentration, and integrity coupled to tissue specificity5 (Supporting Information, Section 1). Recent studies indicated the diagnostic/prognostic potential of dysregulated EV-miRs in adult rheumatic patients.6,7 However, EV-miR expression and potential as biomarkers in OJIA has not been investigated. The aimof this studywas to identify candidate EV-miR-based biomarkers in children with newly diagnosed OJIA. Because joints are the main targets of clinical manifestations in OJIA, we first optimized the protocol for profiling EV-miRs in small volumes of synovial fluid (SF) collected from arthritic joints. We then searched