AbstractExperimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS), is predominantly mediated by pro-inflammatory CD4+ T cell responses to CNS antigens, including myelin proteolipid protein (PLP). Dendritic cells (DCs) are considered critical for inducing T cell responses against infectious agents, but the importance of DCs in priming self-reactive CD4+ T cells in autoimmune disease such as MS has been unclear.To determine the requirement of DCs in PLP-specific CD4+ T cell responses and EAE, we genetically deleted CD11c+ DCs in PLP T cell receptor (TCR) transgenic SJL mice constitutively. DC deficiency did not impair the development, selection or the pathogenic function of PLP-specific CD4+ T cells in these mice, and resulted in accelerated spontaneous EAE compared to DC sufficient controls. In addition, using a genetic approach to ablate DCs conditionally in SJL mice, we show that CD11c+ DCs were dispensable for presenting exogenous or endogenous myelin antigen to PLP-specific T cells and for promoting pro-inflammatory T cell responses and severe EAE. Our findings demonstrate that constitutive or conditional ablation of CD11c+ DCs diminished self-tolerance to PLP autoantigen. They further show that in the absence of DCs, non-DCs can efficiently present CNS myelin antigens such as PLP to self-reactive T cells, resulting in accelerated onset of spontaneous or induced EAE.
Proinflammatory T-cell responses to gut microbiota promote experimental autoimmune encephalomyelitis
