%0 Journal Article
%T Peptides Derived From Insulin Granule Proteins Are Targeted by CD8+ T Cells Across MHC Class I Restrictions in Humans and NOD Mice.
%A Azoury ME
%A Tarayrah M
%A Afonso G
%A Pais A
%A Colli ML
%A Maillard C
%A Lavaud C
%A Alexandre-Heymann L
%A Gonzalez-Duque S
%A Verdier Y
%A Vinh J
%A Pinto S
%A Buus S
%A Dubois-Laforgue D
%A Larger E
%A Beressi JP
%A Bruno G
%A Eizirik DL
%A You S
%A Mallone R
%J Diabetes
%V 69
%N 12
%D 12 2020
%M 32928873
%F 9.337
%R 10.2337/db20-0013
%X The antigenic peptides processed by β-cells and presented through surface HLA class I molecules are poorly characterized. Each HLA variant (e.g., the most common being HLA-A2 and HLA-A3) carries some peptide-binding specificity. Hence, features that, despite these specificities, remain shared across variants may reveal factors favoring β-cell immunogenicity. Building on our previous description of the HLA-A2/A3 peptidome of β-cells, we analyzed the HLA-A3-restricted peptides targeted by circulating CD8+ T cells. Several peptides were recognized by CD8+ T cells within a narrow frequency (1-50/106), which was similar in donors with and without type 1 diabetes and harbored variable effector/memory fractions. These epitopes could be classified as conventional peptides or neoepitopes, generated either via peptide cis-splicing or mRNA splicing (e.g., secretogranin-5 [SCG5]-009). As reported for HLA-A2-restricted peptides, several epitopes originated from β-cell granule proteins (e.g., SCG3, SCG5, and urocortin-3). Similarly, H-2Kd-restricted CD8+ T cells recognizing the murine orthologs of SCG5, urocortin-3, and proconvertase-2 infiltrated the islets of NOD mice and transferred diabetes into NOD/scid recipients. The finding of granule proteins targeted in both humans and NOD mice supports their disease relevance and identifies the insulin granule as a rich source of epitopes, possibly reflecting its impaired processing in type 1 diabetes.