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. doi:10.1172/jci.insight.95193.
View: Text | PDF
Categories: 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

×
Options: View larger image (or click on image)
Mapping affinity and fine-specificity of T cell receptors (TCRs) 380 and...

Figure 1

Mapping affinity and fine-specificity of T cell receptors (TCRs) 380 and 364.

(A and B) Responsiveness of (A) TCC380 and (B) TCC364 to deamidated (E = glutamate) 12mer DQ2.5-glia-α1a and DQ2.5-glia-α2 peptides, respectively, presented by HLA-DQ2.5+ EBV-B cells was assessed by [3H]thymidine incorporation. For TCC364 the responsiveness to deamidated 33mer peptide was also assessed. The dotted line indicates half-maximum response to 12mer peptides and error bars indicate ± SEM of triplicates. (C and D) Representative sensorgrams of (C) scTCR s380 binding to DQ2.5:DQ2.5-glia-α1a (n = 3) and DQ2.5:CLIP2 (n = 3), and (D) binding of scTCR s364 to DQ2.5:DQ2.5-glia-α2 (n = 4) and DQ2.5:CLIP2 (n = 2). n indicates the number of independent experiments performed. (E and F) Peptide overlays of (E) DQ2.5-glia-α1a and DQ2.5-glia-ω1, and (F) of DQ2.5-glia-α2 and DQ2.5-glia-ω2. Peptide sequences are indicated and the residues differing are underlined. Based on the crystal structures of DQ2.5:DQ2.5-glia-α1a (PDB: 1S9V) and DQ2.5:DQ2.5-glia-α2 (PDB: 4OZH) (12, 42). (G and H) Binding of scTCRs s380 (G) and s364 (H) to HLA-DQ2.5-gluten complexes was assessed as indicated. The sensorgrams are representative of n = 1–3 independent experiments.