A Critical Insulin TCR Contact Residue Selects High-Affinity and Pathogenic Insulin-Specific T Cells

A Critical Insulin TCR Contact Residue Selects High-Affinity and Pathogenic Insulin-Specific T Cells


Abstract

Type 1 diabetes is an autoimmune-mediated disease that culminates in the targeted destruction of insulin-producing β-cells. CD4 responses in NOD mice are dominated by insulin epitope B:9-23 (InsB9-23) specificity, and mutation of the key T-cell receptor (TCR) contact residue within the epitope prevents diabetes development. However, it is not clear how insulin self-antigen controls the selection of autoimmune and regulatory T cells (Tregs). Here we demonstrate that mutation of insulin epitope results in escape of highly pathogenic T cells. We observe an increase in antigen reactivity, clonality, and pathogenicity of insulin-specific T cells that develop in the absence of cognate antigen. Using a single TCR system, we demonstrate that Treg development is greatly diminished in mice with the Y16A mutant epitope. Collectively, these results suggest that the tyrosine residue at position 16 is necessary to constrain TCR reactivity for InsB9-23 by both limiting the development of pathogenic T cells and supporting the selection of Tregs.

Footnotes

  • M.Be. and M.L.B. are currently affiliated with the Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT.

  • M.A.S. is currently affiliated with the Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH.

  • This article contains Supplementary Data online at https://diabetes.diabetesjournals.org/lookup/suppl/doi:10.2337/db19-0821/-/DC1.

  • Received August 16, 2019.
  • Accepted December 8, 2019.



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