Intestinal epithelial MHC class II induces encephalitogenic CD4 T cells and initiates central nervous system autoimmunity

The intestinal epithelium plays a critical role in immune-microbiota interactions, yet its contribution to systemic autoimmunity remains unclear. Here, we identify intestinal epithelial cells (IECs) as initiators of experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS). In both EAE mice and patients with MS, IECs up-regulate antigen presentation pathways and are associated with increased intestinal T helper 17 (T_H17) cell accumulation. Epithelial major histocompatibility complex class II (MHC II) was highly expressed during EAE, particularly in the ileum, and its conditional deletion reduced pathogenic T_H17 cell generation and disease severity. Using parabiosis and photoconversion models, we demonstrate that T_H17 cells induced in the intestinal lamina propria migrate to the spinal cord. Functional coculture assays showed that IEC organoids with cognate myelin oligodendrocyte glycoprotein antigen induce RORγt⁺CD4⁺ T cell differentiation in an MHC II-dependent manner. These findings uncover a conserved gut-central nervous system axis in autoimmunity and position epithelial antigen presentation as a key initiator of neuroinflammation.