Blood brain barrier permeability and astrocyte-derived extracellular vesicles in children with juvenile idiopathic arthritis: a cross-sectional study

Juvenile idiopathic arthritis (JIA) is the most prevalent rheumatic disease in children, and the inflammatory process is widely studied, primarily characterized by its impact on joint health. Emerging evidence suggests that JIA may also affect the central nervous system (CNS). This study investigates the potential CNS involvement in JIA by analyzing the presence of astrocyte-derived extracellular vesicles (EVs) and the S100B protein in plasma, both of which are indicative of astrocyte activity and blood-brain barrier (BBB) integrity. EDTA plasma from 90 children diagnosed with JIA and 10 healthy controls, matched by age and gender, was analyzed for extracellular vesicles by flow cytometric measurement. Astrocyte-derived EVs were identified using flow cytometry with markers for aquaporin 4 (AQP-4) and glial fibrillary acidic protein (GFAP). Levels of the S100B protein were measured using a commercial ELISA. Disease activity was assessed using the Juvenile Arthritis Disease Activity Score (JADAS27, 0–57), and pain levels were measured using a visual analogue scale (VAS, 0–10 cm). Our analyses revealed a significantly higher concentration of astrocyte-derived EVs in the plasma of children with JIA compared with healthy controls. Furthermore, children with JADAS27 scores of 1 or higher exhibited notably higher levels of these EVs. The S100B protein was detectable exclusively in the JIA group. The elevated levels of astrocyte-derived EVs and the presence of S100B in children with JIA provide evidence of BBB disruption and CNS involvement, particularly in those with higher disease activity. These findings underscore the importance of considering CNS health in the comprehensive management of JIA. Further research is required to elucidate the mechanisms behind CNS engagement in JIA and to develop treatments that address both joint and CNS manifestations of the disease.