Autoantigen specific T-cell receptor induces organ-specific autoimmunity by escaping T cell negative selection

Abstract

Abstract Previously we reported a new model of spontaneous autoimmune uveitis in which mice with a hypomorphic mutation of Aire (AireGW/+) are combined with deletion of Lyn. The key autoantigen in this model is interphotoreceptor retinoid-binding protein (IRBP) as AireGW/+Lyn−/−IRBP−/− mice failed to develop uveitis. We performed single-cell RNA-seq with TCR sequencing for IRBP 271–290 (P2)-specific CD4+ T cells from eye-draining lymph nodes (LN) of these mice with and without uveitis. Both mice showed an expansion of these T cells in eye-draining LNs, but it was greater in mice with disease. A remarkable clonal diversity of TCRs was seen. Expansions of particular T cell clonotypes were more evident in LN of mice with disease, and even greater in the retinas of mice with disease. We reconstituted several P2–specific TCR clonotypes in a T cell hybridoma line and verified their specificity. One of the TCRs was expressed in thymocytes by retroviral transduction of bone marrow stem cells from Rag2−/− mice and transplanted into WT or AireGW/+ recipient mice. Remarkably, the small residual expression of IRBP in the thymus of AireGW/+ mice was sufficient to induce substantial negative selection of thymocytes with this TCR. In addition, we generated TCR transgenic mice with this TCR clonotype. The TCR transgenic mice spontaneously developed uveitis with expansion of P2-specific CD4+ T cells. Combined with AireGW/+ or IRBP−/−, there were more P2-specific CD4+ T cells in the thymus of TCR transgenic mice. Thus, suboptimal Aire function in AireGW/+Lyn−/− mice results in a partial defect in negative selection of T cells recognizing IRBP in the thymus, promoting development of uveitis. This disease is accelerated in mice expressing a TCR transgene recognizing IRBP. Supported by AI138479