Updated project metadata. Blood-brain-barrier (BBB) breakdown and active inflammation by relapsing–remitting (RRMS) lesions are hallmarks of multiple sclerosis (MS). Leaky endothelial junctions causes an increased expression of circulating immune cells with associated adhesion molecules on endothelial cell membrane but also an increased production of endothelial derived extracellular microvesicles (EV). Methods: Relapsing–remitting MS (RRMS) patients with no disease-modifying treatment were monitored with weekly intervals using high-resolution 3T MRI scanning. Plasma samples from each measurement were analyzed for protein biomarkers of inflammation by quantitative proteomics, cytokines and chemokines using multiplex immunoassay. Extracellular microvesicles were characterized by an optimized endothelial stress EV Array analysis for detection of soluble secreted microvesicles.