Neuronal IκB Kinase β Protects Mice from Autoimmune Encephalomyelitis by Mediating Neuroprotective and Immunosuppressive Effects in the Central Nervous System

Some aspects of CNS-directed autoimmunity in multiple sclerosis are modeled in mice by immunization with myelin Ags where tissue damage is driven by myelin-reactive Th1 and Th17 effector lymphocytes. Whether the CNS plays an active role in controlling such autoimmune diseases is unknown. We used mice in which I kappa B kinase beta was deleted from Ca(2+)/calmodulin-dependent kinase II alpha-expressing neurons (nIKK beta KO) to investigate the contribution of neuronal NF-kappa B to the development of myelin oligodendrocyte glycoprotein 35-55-induced experimental autoimmune encephalomyelitis. We show that nIKK beta KO mice developed a severe, nonresolving disease with increased axon loss compared with controls and this was associated with significantly reduced CNS production of neuroprotective factors (vascular endothelial growth factor, CSF1-R, and FLIP) and increased production of proinflammatory cytokines (IL-6, TNF, IL-12, IL-17, and CD30L) and chemokines. The isolation of CNS-infiltrating monocytes revealed greater numbers of CD4(+) T cells, reduced numbers of NK1.1(+) cells, and a selective accumulation of Th1 cells in nIKK beta KO CNS from early in the disease. Our results show that neurons play an important role in determining the quality and outcome of CNS immune responses, specifically that neuronal I kappa B kinase beta is required for neuroprotection, suppression of inflammation, limitation of Th1 lymphocyte accumulation, and enhancement of NK cell recruitment in experimental autoimmune encephalomyelitis-affected CNS and stress the importance of neuroprotective strategies for the treatment of multiple sclerosis. The Journal of Immunology, 2009, 183: 7877-7889.