Hotspot autoimmune T cell receptor binding underlies pathogen and insulin peptide cross-reactivity
David K. Cole, … , Pierre J. Rizkallah, Andrew K. Sewell
David K. Cole, … , Pierre J. Rizkallah, Andrew K. Sewell
Published May 16, 2016
Citation Information: J Clin Invest. 2016;126(6):2191-2204. https://doi.org/10.1172/JCI85679.
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Research Article Autoimmunity Immunology Article has an altmetric score of 230

Hotspot autoimmune T cell receptor binding underlies pathogen and insulin peptide cross-reactivity

Abstract

The cross-reactivity of T cells with pathogen- and self-derived peptides has been implicated as a pathway involved in the development of autoimmunity. However, the mechanisms that allow the clonal T cell antigen receptor (TCR) to functionally engage multiple peptide–major histocompatibility complexes (pMHC) are unclear. Here, we studied multiligand discrimination by a human, preproinsulin reactive, MHC class-I–restricted CD8+ T cell clone (1E6) that can recognize over 1 million different peptides. We generated high-resolution structures of the 1E6 TCR bound to 7 altered peptide ligands, including a pathogen-derived peptide that was an order of magnitude more potent than the natural self-peptide. Evaluation of these structures demonstrated that binding was stabilized through a conserved lock-and-key–like minimal binding footprint that enables 1E6 TCR to tolerate vast numbers of substitutions outside of this so-called hotspot. Highly potent antigens of the 1E6 TCR engaged with a strong antipathogen-like binding affinity; this engagement was governed though an energetic switch from an enthalpically to entropically driven interaction compared with the natural autoimmune ligand. Together, these data highlight how T cell cross-reactivity with pathogen-derived antigens might break self-tolerance to induce autoimmune disease.

Authors

David K. Cole, Anna M. Bulek, Garry Dolton, Andrea J. Schauenberg, Barbara Szomolay, William Rittase, Andrew Trimby, Prithiviraj Jothikumar, Anna Fuller, Ania Skowera, Jamie Rossjohn, Cheng Zhu, John J. Miles, Mark Peakman, Linda Wooldridge, Pierre J. Rizkallah, Andrew K. Sewell

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Figure 7

The 1E6 TCR makes distinct peptide contacts with the MHC surface depending on the peptide cargo.

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The 1E6 TCR makes distinct peptide contacts with the MHC surface dependi...
Interactions between the 1E6 TCR and the MHC α1 helix residues Arg65, Lys66, and Gln72. Hydrogen bonds are shown as red dotted lines; vdW contacts are shown as black dotted lines. MHCα1 helix are shown in gray illustrations. Boxes show total contacts between the 1E6 TCR and these key residues (green boxes are MHC residues; white boxes are TCR residues). (A) Interaction between the 1E6 TCR (black illustration and sticks) and A2-MVWGPDPLYV (black illustration and sticks). (B) Interaction between the 1E6 TCR (red illustration and sticks) and A2-YLGGPDFPTI (red illustration and sticks). (C) Interaction between the 1E6 TCR (blue illustration and sticks) and A2-ALWGPDPAAA (blue illustration and sticks) reproduced from previous published data (21). (D) Interaction between the 1E6 TCR (green illustration and sticks) and A2-AQWGPDPAAA (green illustration and sticks). (E) Interaction between the 1E6 TCR (dark blue illustration and sticks) and A2-RQFGPDWIVA (dark blue illustration and sticks). (F) Interaction between the 1E6 TCR (purple illustration and sticks) and A2-RQWGPDPAAV (purple illustration and sticks). (G) Interaction between the 1E6 TCR (yellow illustration and sticks) and A2-YQFGPDFPIA (yellow illustration and sticks). (H) Interaction between the 1E6 TCR (cyan illustration and sticks) and A2-RQFGPDFPTI (cyan illustration and sticks).