Discriminative T-cell receptor recognition of highly homologous HLA-DQ2-bound gluten epitopes.
J Biol Chem
; 294(3): 941-952, 2019 01 18.
Article
em En
| MEDLINE
| ID: mdl-30455354
ABSTRACT
Celiac disease (CeD) provides an opportunity to study the specificity underlying human T-cell responses to an array of similar epitopes presented by the same human leukocyte antigen II (HLA-II) molecule. Here, we investigated T-cell responses to the two immunodominant and highly homologous HLA-DQ2.5-restricted gluten epitopes, DQ2.5-glia-α1a (PFPQPELPY) and DQ2.5-glia-ω1 (PFPQPEQPF). Using HLA-DQ2.5-DQ2.5-glia-α1a and HLA-DQ2.5-DQ2.5-glia-ω1 tetramers and single-cell αß T-cell receptor (TCR) sequencing, we observed that despite similarity in biased variable-gene usage in the TCR repertoire responding to these nearly identical peptide-HLA-II complexes, most of the T cells are specific for either of the two epitopes. To understand the molecular basis of this exquisite fine specificity, we undertook Ala substitution assays revealing that the p7 residue (Leu/Gln) is critical for specific epitope recognition by both DQ2.5-glia-α1a- and DQ2.5-glia-ω1-reactive T-cell clones. We determined high-resolution binary crystal structures of HLA-DQ2.5 bound to DQ2.5-glia-α1a (2.0 Å) and DQ2.5-glia-ω1 (2.6 Å). These structures disclosed that differences around the p7 residue subtly alter the neighboring substructure and electrostatic properties of the HLA-DQ2.5-peptide complex, providing the fine specificity underlying the responses against these two highly homologous gluten epitopes. This study underscores the ability of TCRs to recognize subtle differences in the peptide-HLA-II landscape in a human disease setting.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Peptídeos
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Receptores de Antígenos de Linfócitos T
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Linfócitos T
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Antígenos HLA-DQ
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Apresentação de Antígeno
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Epitopos de Linfócito T
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Glutens
Tipo de estudo:
Prognostic_studies
Limite:
Female
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Humans
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Male
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article