title: HLA-B7-restricted islet epitopes are differentially recognized in type 1 diabetic children and adults and form weak peptide-HLA complexes.
abstract: The cartography of β-cell epitopes targeted by CD8(+) T cells in type 1 diabetic (T1D) patients remains largely confined to the common HLA-A2 restriction. We aimed to identify β-cell epitopes restricted by the HLA-B7 (B*07:02) molecule, which is associated with mild T1D protection. Using DNA immunization on HLA-B7-transgenic mice and prediction algorithms, we identified GAD and preproinsulin candidate epitopes. Interferon-γ (IFN-γ) enzyme-linked immunospot assays on peripheral blood mononuclear cells showed that most candidates were recognized by new-onset T1D patients, but not by type 2 diabetic and healthy subjects. Some epitopes were highly immunodominant and specific to either T1D children (GAD(530-538); 44% T cell-positive patients) or adults (GAD(311-320); 38%). All epitopes displayed weak binding affinity and stability for HLA-B7 compared with HLA-A2-restricted ones, a general feature of HLA-B7. Single-cell PCR analysis on β-cell-specific (HLA-B7 tetramer-positive) T cells revealed uniform IFN-γ and transforming growth factor-β (TGF-β) mRNA expression, different from HLA-A2-restricted T cells. We conclude that HLA-B7-restricted islet epitopes display weak HLA-binding profiles, are different in T1D children and adults, and are recognized by IFN-γ(+)TGF-β(+)CD8(+) T cells. These features may explain the T1D-protective effect of HLA-B7. The novel epitopes identified should find valuable applications for immune staging of HLA-B7(+) individuals.
authors.affiliation: INSERM, U986, DeAR Lab Avenir, Cochin-Saint Vincent de Paul Hospital, Paris, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Scotto
authors.forename: Georgia
authors.initials: G
authors.lastname: Afonso
authors.forename: Thomas
authors.initials: T
authors.lastname: Østerbye
authors.forename: Etienne
authors.initials: E
authors.lastname: Larger
authors.forename: Sandrine
authors.initials: S
authors.lastname: Luce
authors.forename: Cécile
authors.initials: C
authors.lastname: Raverdy
authors.forename: Giulia
authors.initials: G
authors.lastname: Novelli
authors.forename: Graziella
authors.initials: G
authors.lastname: Bruno
authors.forename: Céline
authors.initials: C
authors.lastname: Gonfroy-Leymarie
authors.forename: Odile
authors.initials: O
authors.lastname: Launay
authors.forename: François A
authors.initials: FA
authors.lastname: Lemonnier
authors.forename: Søren
authors.initials: S
authors.lastname: Buus
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Carel
authors.forename: Christian
authors.initials: C
authors.lastname: Boitard
authors.forename: Roberto
authors.initials: R
authors.lastname: Mallone
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D005260:Female; D015793:HLA-B7 Antigen / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D007371:Interferon-gamma / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008875:Middle Aged; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D000939:Epitopes; D015793:HLA-B7 Antigen; D016212:Transforming Growth Factor beta; D007371:Interferon-gamma