High diversity in the TCR repertoire of self-antigen-specific CD4 T cells in Autoimmune encephalomyelitis 3419

Abstract Description Autoimmune disorders affect 10.2% of individuals, with rising incidences, often due to a breakdown in self-tolerance triggered by unknown factors. EAE is a T-cell-mediated model of MS, induced by immunization with the self-antigen MOG35-55. Historical TCR repertoire analyses lacked modern, unbiased technologies to assess the full breadth of MOG-specific αβTCRs, their phenotypes, and tissue distribution. We analyzed the CD4 T cell TCR repertoire in EAE-induced C57BL/6J mice at the single-cell level. Using affinity-enhanced MOG-tetramers and short-term peptide stimulation assays, we assessed paired gene expression and αβTCR repertoire, yielding 42,539 TCR sequences. Phenotypic heterogeneity was observed, with hyperexpanded clones showing TH17 and TH1/TH17 profiles. Clone sharing between peripheral and central compartments was noted among 141 of 191 clones, with 36 being publicly shared. Comparison with viral (LCMV-gp66) TCR repertoire revealed that the MOG TCR repertoire is more diverse and less clonal and differed in αβ V-gene usage. We identified TCRα and TCRβ CDR3 motifs and propose investigating cross-reactivity against other CNS antigens, suggesting epitope spreading. Through retrogenic and adoptive transfer approaches, we aim to assess CNS trafficking, distribution, and competition of these autoreactive TCRs as disease progresses. Overall, our study enhances the understanding of CD4 T cell immune responses to self-antigens and autoimmune diseases. Funding Sources NINDS 1U01NS120836-01; National Multiple Sclerosis Career Transition Fellowship Topic Categories Basic Autoimmunity (BA)