Citation

Activation and pathogenic potential of MOG-specific B cells in spontaneous experimental autoimmune encephalomyelitis Activation and pathogenic potential of MOG-specific B cells in spontaneous experimental autoimmune encephalomyelitis Multiple Sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system (CNS) predominantly mediated by self-reactive T and B cells. T cells have been long considered as major players in disease development. However, the success of B cell depletion therapies in MS patients highlights a complex role of B cells in disease initiation and progression. B cells can have both proinflammatory and regulatory effects. They can produce potentially pathogenic autoantibodies, act as antigen-presenting cells (APCs), and/or secrete cytokines shaping the local milieu. Actively induced Experimental Autoimmune Encephalomyelitis (EAE), the most common animal model of MS, is not optimally suited to study the role of B cells in autoimmune responses, as immunization with myelin peptide bypasses antigen processing and presentation by B cells. However, spontaneous EAE (sEAE) mouse models featuring transgenic T cell receptors (TCRs) specific for myelin oligodendrocyte glycoprotein (MOG) develop B cell-dependent disease, and can thus provide insights into the role of B cells in initiation of pathogenesis. To evaluate when and where B cells become activated in sEAE possible activation sites were investigated with different methodological approaches. First, we tried to determine whether myelin proteins from the CNS are transported to cervical lymph nodes (CLNs) in soluble form or via exosomes in spontaneous relapsing-remitting EAE (TCR1640 mice) to investigate if autoreactive B cells are activated directly in CLNs. Alternatively, B cells might be activated in a different place and recruited to CLNs. Therefore, we explored the intestine as a potential site for priming of auto-reactive B cells via B cell transfer and activation studies. However, as B cell analysis ex vivo and functional studies were not feasible due to low B cell frequencies in the intestine after transfer, in this study we focused on establishing a new B cell culture system, allowing expansion, differentiation, and manipulation of primary B cells and testing the use of this system for studying pathogenic properties of B cells upon transfer in vivo. After successful establishment of in vitro induced germinal center B cell (iGB) culture, we adoptively transferred MOG-specific iGB cells (from a mouse model expressing a MOG-specific BCR, called TH mouse), into 2D2 mice, which carry a transgenic MOG-specific TCR, to test their pathogenic potential. Results demonstrated that MOG-specific iGB cells can trigger development of EAE. These data support a role of B cells in the initiation of EAE probably acting as APCs. In summary, the new B cell culture system is a unique tool to expand and manipulate B cells and thereby characterize their role in the development of EAE and MS. Not available