B Lymphocytes from MS Patients Induce CNS Pathology in a Murine Brain Slice Model

Objective: Discover mechanisms by which B cells may drive MS pathogenesis.Background: Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS), featuring demyelination, activated lymphocytes, astrogliosis, and axonal loss. Suppression of disease progression via B cell-targeted therapies indicates important roles for B cells, requiring further studies of B cell mechanisms.Design/Methods: Cerebellar slice cultures were generated from P10 mice and cultured for 12 days. CD19+ B cells were isolated from peripheral blood mononuclear cells of patients and controls, then added to cerebellar slice cultures or astrocyte cell cultures for 24-96 hours. Slices or cells were fixed and immunostained; media was collected for cytokine analysis. In other studies, B cells were isolated from mice and exposed to stimuli before culturing with cortical murine astrocytes, then analyzed for GFAP reactivity and iNOS production.Results: B cells from MS patients, but not controls, induced astrocyte and microglia morphological changes, oligodendrocyte loss, and demyelination. In order to analyze astrocyte responses, we treated primary astrocyte cultures with murine B cells stimulated under different conditions, or human B cells isolated from MS patients. Under specific activating conditions, murine B cells altered astrocyte morphology, upregulated GFAP expression and intracellular iNOS. Evaluating the astrocyte responses to B lymphocytes from untreated MS patients or controls is currently in progress, as well as identifying mechanisms of B lymphocyte mediated CNS pathology.Conclusions: B cells from MS patients mediate CNS pathology in organotypic slices similar to that observed in histological studies of MS tissue. These effects include morphological changes in astrocytes, oligodendrocyte death, and demyelination. This system will allow for the identification of the target cell(s), as well as assist in identifying key unknown biological mechanisms underlying MS.This study was funded by an Independent Medical Grant from EMD Serono and the Rocky Mountain Multiple Sclerosis Center. Disclosure: Dr. Harlow has received personal compensation for activities with Teva Pharmaceuticals. Dr. Blauth has received personal compensation for activities with Mallinckrodt Pharmaceuticals. Dr. Saul has nothing to disclose. Dr. Selva has nothing to disclose. Dr. Niedzielko has nothing to disclose. Dr. Jackson has received personal compensation for activities9 with Teva Pharmaceuticals. Dr. Macklin has received personal compensation for activities with Renovo Neural Inc. Dr. Vollmer has received personal compensation for activities with Acorda Therapeutics, Biogen Idec, Genentech, Inc., Novartis, Ono Pharmaceutical, Teva Neuroscience, and XenoPort as a consultant.