Sunlight-mediated Inter-organ Leukocyte Exchange

Ultraviolet B (UVB) irradiation induces regulatory immune cell types that may transmigrate from the skin to the blood and to the central nervous system and exert regulatory effects. Vitamin D deficiency-associated gene variants should reduce this effect if this is mediated by vitamin D. For this study, participants will be irradiated with UVB for 4 weeks. Single cell RNA Sequencing will be performed on isolated immune cells from skin, blood and Cerebrospinal fluid (CSF), before and after irradiation.

Inclusion Criteria:RRMS according to revised McDonald criteria (2017) or healthy volunteerPatients under treatment of natalizumab, teriflunomide, glatirameracetat or dimethyl fumarate for at least 4 weeks of therapy, or therapy-naïve patients will be includedExclusion Criteria:Patients receiving treatment in the last 3 months of interferon-β, fingolimod, alemtuzumab, ocrelizumab, cladribine, ofatumumab, ozanimod, or ponesimodVitamin D supplementation in the last 8 weeksUVB-narrowband contraindicated skin diseases (e.g., cutaneous neoplasia)Lacking the ability to stand on their own in the treatment chamberSigns of intolerance regarding UVB radiationIntake of UV-sensitive therapeuticsFurther autoimmune diseases (e.g., Morbus Crohn, psoriasis, neurodermatitis)Additional recreational or therapeutic UV radiation (e.g., solarium)