A TCRα framework–centered codon shapes a biased T cell repertoire through direct MHC and CDR3β interactions
Kristin Støen Gunnarsen, … , Inger Sandlie, Geir Åge Løset
Kristin Støen Gunnarsen, … , Inger Sandlie, Geir Åge Løset
Published September 7, 2017
Citation Information: JCI Insight. 2017;2(17):e95193. https://doi.org/10.1172/jci.insight.95193.
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Research Article Immunology

A TCRα framework–centered codon shapes a biased T cell repertoire through direct MHC and CDR3β interactions

Abstract

Selection of biased T cell receptor (TCR) repertoires across individuals is seen in both infectious diseases and autoimmunity, but the underlying molecular basis leading to these shared repertoires remains unclear. Celiac disease (CD) occurs primarily in HLA-DQ2.5+ individuals and is characterized by a CD4+ T cell response against gluten epitopes dominated by DQ2.5-glia-α1a and DQ2.5-glia-α2. The DQ2.5-glia-α2 response recruits a highly biased TCR repertoire composed of TRAV26-1 paired with TRBV7-2 harboring a semipublic CDR3β loop. We aimed to unravel the molecular basis for this signature. By variable gene segment exchange, directed mutagenesis, and cellular T cell activation studies, we found that TRBV7-3 can substitute for TRBV7-2, as both can contain the canonical CDR3β loop. Furthermore, we identified a pivotal germline-encoded MHC recognition motif centered on framework residue Y40 in TRAV26-1 engaging both DQB1*02 and the canonical CDR3β. This allowed prediction of expanded DQ2.5-glia-α2–reactive TCR repertoires, which were confirmed by single-cell sorting and TCR sequencing from CD patient samples. Our data refine our understanding of how HLA-dependent biased TCR repertoires are selected in the periphery due to germline-encoded residues.

Authors

Kristin Støen Gunnarsen, Lene Støkken Høydahl, Louise Fremgaard Risnes, Shiva Dahal-Koirala, Ralf Stefan Neumann, Elin Bergseng, Terje Frigstad, Rahel Frick, M. Fleur du Pré, Bjørn Dalhus, Knut E.A. Lundin, Shuo-Wang Qiao, Ludvig M. Sollid, Inger Sandlie, Geir Åge Løset

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Figure 2

Responsiveness of T cell receptor (TCR) 380 and TCR 364 as reconstructed membrane-bound receptors.

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Responsiveness of T cell receptor (TCR) 380 and TCR 364 as reconstructed...
The ability of BW T cells retrovirally transduced with either TCR 380 or TCR 364 to respond to a panel of gluten peptides was monitored by measuring IL-2 secretion. (A and B) HLA-DQ2.5+ EBV-B cells were loaded with titrated amounts of 12mer peptides as indicated before addition of BW T cells. Both deamidated (E) and native (Q) peptides were used. Representative responses of (A) BW 380 T cells and (B) BW 364 T cells are shown. (C and D) HLA-DQ2.5+ EBV-B cells were loaded with titrated amounts of 33mer α-gliadin peptide (E or Q) containing both the DQ2.5-glia-α1a and DQ2.5-glia-α2 epitopes, or with 17mer/19mer ω-gliadin peptide (E and Q, respectively) containing both the DQ2.5-glia-ω1 and DQ2.5-glia-ω2 epitopes. Representative IL-2 responses of (C) BW 380 T cells and (D) BW 364 T cells are shown. (E and F) Titrated amounts of A20 B cells expressing HLA-DQ2.5 with covalently linked peptide were used as antigen-presenting cells (APCs) to stimulate (E) BW 380 T cells and (D) BW 364 T cells. Wo = without T and A are controls with T cells or APCs with peptide alone. Error bars indicate ± SD of triplicates. (A–F) The experiment in each panel was performed 3 independent times. Figures were prepared using GraphPad Prism 7, and nonlinear regression analysis (3 parameters) was used to derive IL-2 concentrations from the standard curves.