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Noncontiguous T cell epitopes in autoimmune diabetes: From mice to men and back again

  • Nitin Amdare
    Affiliations
    Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA
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  • Anthony W. Purcell
    Affiliations
    Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
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  • Teresa P. DiLorenzo
    Correspondence
    For correspondence: Teresa P. DiLorenzo
    Affiliations
    Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA

    Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA

    Einstein-Mount Sinai Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York, USA

    The Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, New York, USA
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Open AccessPublished:May 24, 2021DOI:https://doi.org/10.1016/j.jbc.2021.100827
      Type 1 diabetes (T1D) is a T cell–mediated autoimmune disease that affects the insulin-producing beta cells of the pancreatic islets. The nonobese diabetic mouse is a widely studied spontaneous model of the disease that has contributed greatly to our understanding of T1D pathogenesis. This is especially true in the case of antigen discovery. Upon review of existing knowledge concerning the antigens and peptide epitopes that are recognized by T cells in this model, good concordance is observed between mouse and human antigens. A fascinating recent illustration of the contribution of the nonobese diabetic mouse in the area of epitope identification is the discovery of noncontiguous CD4+ T cell epitopes. This novel epitope class is characterized by the linkage of an insulin-derived peptide to, most commonly, a fragment of a natural cleavage product of another beta cell secretory granule constituent. These so-called hybrid insulin peptides are also recognized by T cells in patients with T1D, although the precise mechanism for their generation has yet to be defined and is the subject of active investigation. Although evidence from the tumor immunology arena documented the existence of noncontiguous CD8+ T cell epitopes, generated by proteasome-mediated peptide splicing involving transpeptidation, such CD8+ T cell epitopes were thought to be a rare immunological curiosity. However, recent advances in bioinformatics and mass spectrometry have challenged this view. These developments, coupled with the discovery of hybrid insulin peptides, have spurred a search for noncontiguous CD8+ T cell epitopes in T1D, an exciting frontier area still in its infancy.

      Keywords

      Abbreviations:

      APC (antigen-presenting cell), HIP (hybrid insulin peptide), IEDB (Immune Epitope Database), MHC (major histocompatibility complex), NOD (nonobese diabetic), PaLN (pancreatic lymph node), T1D (type 1 diabetes), TCR (T cell receptor)
      Beta cells in the pancreatic islets of Langerhans synthesize and secrete insulin, a hormone required for glucose utilization and homeostasis. In autoimmune diabetes, also known as type 1 diabetes (T1D), beta cells are destroyed by T cells that have been activated by islet-derived peptides bound to major histocompatibility complex (MHC) molecules, either displayed by the beta cells themselves or by professional antigen-presenting cells (APCs) (
      • Pugliese A.
      Autoreactive T cells in type 1 diabetes.
      ). Consistent with the presence of CD4+ and CD8+ T cells specific for beta cell–derived peptides in the islets of donors with T1D (
      • Babon J.A.
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      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      ), both T cell subsets are believed to participate in beta cell elimination. Based on studies in rodent models, T cells likely employ a variety of mechanisms to achieve this end, including Fas-mediated apoptosis and the release of effector molecules such as perforin, granzyme, and the cytokines interferon-γ and tumor necrosis factor-α (
      • Dudek N.L.
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      • Trapani J.A.
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      • Thomas H.E.
      Perforin and Fas induced by IFNγ and TNFα mediate beta cell death by OT-I CTL.
      ). In the absence of a sufficient beta cell mass, exogenous insulin becomes necessary for survival.
      T1D is a complex disease with both genetic and environmental components (
      • Katsarou A.
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      ). Polymorphisms in dozens of genes contribute to disease susceptibility or resistance (
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      Genetics of type 1 diabetes.
      ). The majority are expressed by cells of the immune system or by the pancreatic beta cells themselves, reflecting a complicated interplay between autoreactive T cells and beta cells. Environmental triggers (e.g., viral infection or dietary components) that initiate an often protracted, and initially asymptomatic, autoimmune process in genetically susceptible individuals are assumed, but remain ill-defined (
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      ). Adding to the complexity is the finding of serum autoantibodies to beta cell proteins, often years before the onset of clinical symptoms (
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      ). Although autoantibodies are of great utility in predicting individuals who will develop T1D, a pathogenic role for the autoantibodies has not been established, and the disease is viewed as being mediated by T cells rather than by antibodies.
      Given the essential role of T cell epitopes in the pathogenesis of T1D, it is unsurprising that multiple benefits have been derived from their identification, and others can be readily envisioned. Knowledge regarding the T cell epitopes in T1D has provided critical insights into the mechanistic basis of the disease process. For example, it was once satisfying to believe that patients with T1D would harbor T cells specific for beta cell antigens, whereas healthy controls would be devoid of them, having been successfully purged of autoreactive T cells by the central tolerance mechanism of thymic negative selection. However, the identification of T cell epitopes in T1D now allows T cells specific for beta cell antigens to be quantitatively and functionally assessed (albeit thus far for research purposes only), leading to the important realization that CD4+ and CD8+ T cells reactive to beta cell peptides are present in both health and disease (
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      ). Yet, differences in T cell numbers and/or function are often noted when the two states are compared (
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      T-cell epitopes and neo-epitopes in type 1 diabetes: A comprehensive update and reappraisal.
      ), suggesting the potential utility of antigen-specific T cell assays for immune monitoring, e.g., in disease prevention and reversal trials, or as diagnostic tools. The promise and feasibility of T cell–based assays in a clinical setting is exemplified by the interferon-γ release assays that are currently used in the diagnosis of latent Mycobacterium tuberculosis (Mtb) infection (
      • Whitworth H.S.
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      ). In these assays, peripheral blood cells are exposed to peptides derived from known Mtb antigens, and Mtb-specific T cells are detected by the interferon-γ they release in response to recognition of their cognate epitopes. Finally, in addition to representing important components of a future clinical assay to detect beta cell–specific T cells, T cell epitopes are also being explored in clinical trials as preventive or therapeutic agents for T1D (
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      ).
      With the above goals and opportunities in mind, discovery of T cell epitopes in T1D continues to be an active area of investigation, and the known peptides recognized by T1D-associated T cells in humans have recently been compiled and evaluated (
      • James E.A.
      • Mallone R.
      • Kent S.C.
      • DiLorenzo T.P.
      T-cell epitopes and neo-epitopes in type 1 diabetes: A comprehensive update and reappraisal.
      ). Although the majority of the epitopes identified to date are conventional peptides, T1D-associated T cell epitopes may also be posttranslationally modified or otherwise unconventional (
      • James E.A.
      • Mallone R.
      • Kent S.C.
      • DiLorenzo T.P.
      T-cell epitopes and neo-epitopes in type 1 diabetes: A comprehensive update and reappraisal.
      ) (Fig. 1). In view of the known clinical importance of an immune response to posttranslationally modified peptides in rheumatoid arthritis (
      • Darrah E.
      • Andrade F.
      Rheumatoid arthritis and citrullination.
      ) and celiac disease (
      • Sollid L.M.
      The roles of MHC class II genes and post-translational modification in celiac disease.
      ), there is currently considerable interest in unconventional epitopes in T1D as well. The collection of biochemical processes that create unconventional T cell epitopes in T1D (Fig. 1) includes disulfide bond formation (
      • Mannering S.I.
      • Harrison L.C.
      • Williamson N.A.
      • Morris J.S.
      • Thearle D.J.
      • Jensen K.P.
      • Kay T.W.
      • Rossjohn J.
      • Falk B.A.
      • Nepom G.T.
      • Purcell A.W.
      The insulin A-chain epitope recognized by human T cells is posttranslationally modified.
      ), deamidation (
      • Babon J.A.
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      • Blodgett D.M.
      • Crevecoeur I.
      • Buttrick T.S.
      • Maehr R.
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      • James E.A.
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      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      ,
      • Marre M.L.
      • McGinty J.W.
      • Chow I.T.
      • DeNicola M.E.
      • Beck N.W.
      • Kent S.C.
      • Powers A.C.
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      • Harlan D.M.
      • Greenbaum C.J.
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      ), citrullination (
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      • Buttrick T.S.
      • Maehr R.
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      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      ,
      • Marre M.L.
      • McGinty J.W.
      • Chow I.T.
      • DeNicola M.E.
      • Beck N.W.
      • Kent S.C.
      • Powers A.C.
      • Bottino R.
      • Harlan D.M.
      • Greenbaum C.J.
      • Kwok W.W.
      • Piganelli J.D.
      • James E.A.
      Modifying enzymes are elicited by ER stress, generating epitopes that are selectively recognized by CD4+ T cells in patients with type 1 diabetes.
      ,
      • McGinty J.W.
      • Chow I.T.
      • Greenbaum C.
      • Odegard J.
      • Kwok W.W.
      • James E.A.
      Recognition of posttranslationally modified GAD65 epitopes in subjects with type 1 diabetes.
      ,
      • Buitinga M.
      • Callebaut A.
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      • Crevecoeur I.
      • Blahnik-Fagan G.
      • Yang M.L.
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      ,
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      ), phosphorylation (
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      • Bajzik V.
      • Piganelli J.D.
      • James E.A.
      T cell epitopes and post-translationally modified epitopes in type 1 diabetes.
      ), alternative open reading frame usage (
      • Kracht M.J.
      • van Lummel M.
      • Nikolic T.
      • Joosten A.M.
      • Laban S.
      • van der Slik A.R.
      • van Veelen P.A.
      • Carlotti F.
      • de Koning E.J.
      • Hoeben R.C.
      • Zaldumbide A.
      • Roep B.O.
      Autoimmunity against a defective ribosomal insulin gene product in type 1 diabetes.
      ), and translation of alternatively spliced RNA transcripts (
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
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      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      ,
      • Gonzalez-Duque S.
      • Azoury M.E.
      • Colli M.L.
      • Afonso G.
      • Turatsinze J.V.
      • Nigi L.
      • Lalanne A.I.
      • Sebastiani G.
      • Carre A.
      • Pinto S.
      • Culina S.
      • Corcos N.
      • Bugliani M.
      • Marchetti P.
      • Armanet M.
      • et al.
      Conventional and neo-antigenic peptides presented by β cells are targeted by circulating naive CD8+ T cells in type 1 diabetic and healthy donors.
      ). The formation of noncontiguous T cell epitopes, first revealed by the nonobese diabetic (NOD) mouse model of autoimmune diabetes (
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
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      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ), is a fascinating recent addition to this list that has generated enormous excitement and spawned new avenues of research for T1D investigators (
      • Babon J.A.
      • DeNicola M.E.
      • Blodgett D.M.
      • Crevecoeur I.
      • Buttrick T.S.
      • Maehr R.
      • Bottino R.
      • Naji A.
      • Kaddis J.
      • Elyaman W.
      • James E.A.
      • Haliyur R.
      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      ,
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
      • Verdier Y.
      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      ,
      • Gonzalez-Duque S.
      • Azoury M.E.
      • Colli M.L.
      • Afonso G.
      • Turatsinze J.V.
      • Nigi L.
      • Lalanne A.I.
      • Sebastiani G.
      • Carre A.
      • Pinto S.
      • Culina S.
      • Corcos N.
      • Bugliani M.
      • Marchetti P.
      • Armanet M.
      • et al.
      Conventional and neo-antigenic peptides presented by β cells are targeted by circulating naive CD8+ T cells in type 1 diabetic and healthy donors.
      ,
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ,
      • Arribas-Layton D.
      • Guyer P.
      • Delong T.
      • Dang M.
      • Chow I.T.
      • Speake C.
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      • Kwok W.W.
      • Baker R.L.
      • Haskins K.
      • James E.A.
      Hybrid insulin peptides are recognized by human T cells in the context of DRB1∗04:01.
      ,
      • Baker R.L.
      • Jamison B.L.
      • Wiles T.A.
      • Lindsay R.S.
      • Barbour G.
      • Bradley B.
      • Delong T.
      • Friedman R.S.
      • Nakayama M.
      • Haskins K.
      CD4 T cells reactive to hybrid insulin peptides are indicators of disease activity in the NOD mouse.
      ,
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      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      ,
      • Wiles T.A.
      • Delong T.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Powell R.L.
      • Reisdorph N.
      • Haskins K.
      An insulin-IAPP hybrid peptide is an endogenous antigen for CD4 T cells in the non-obese diabetic mouse.
      ).
      Figure thumbnail gr1
      Figure 1Unconventional T cell epitopes in T1D. Besides the formation of noncontiguous T cell epitopes, the focus of this review, a number of other processes create unconventional T cell epitopes in T1D. Alternative open reading frame (ORF) usage and translation of alternatively spliced RNA transcripts can both lead to the formation of novel proteins. The proteasome processes both novel and standard proteins for presentation on class I MHC molecules. It also participates in the formation of noncontiguous CD8+ T cell epitopes (cis- and trans-spliced peptides; black arrows denote the border between the two peptide segments). Noncontiguous CD4+ T cell epitopes (hybrid insulin peptides, or HIPs; dual-colored) likely form in the beta cell secretory granules and crinosomes. For presentation of HIPs on class II MHC molecules, islet APCs can acquire intact secretory granules, with their HIPs, from beta cells, while exocytosed crinosome peptides can be released from beta cells into the circulation and captured by APCs in peripheral lymphoid organs and blood. Deamidation, citrullination, disulfide bond formation, and phosphorylation can also contribute to the formation of unconventional T cell epitopes in T1D (lower left). Their exact cellular and subcellular origins have not been fully elucidated, although deamidation by tissue transglutaminase (tTG) and citrullination by protein-arginine deiminase (PAD) are thought to occur in both beta cells and APCs (
      • McLaughlin R.J.
      • de Haan A.
      • Zaldumbide A.
      • de Koning E.J.
      • de Ru A.H.
      • van Veelen P.A.
      • van Lummel M.
      • Roep B.O.
      Human islets and dendritic cells generate post-translationally modified islet autoantigens.
      ,
      • Ireland J.M.
      • Unanue E.R.
      Autophagy in antigen-presenting cells results in presentation of citrullinated peptides to CD4 T cells.
      ,
      • Rondas D.
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      • Mathieu C.
      Citrullinated glucose-regulated protein 78 is an autoantigen in type 1 diabetes.
      ). Readers are referred to the text for relevant additional citations. APC, antigen-presenting cell; T1D, type 1 diabetes.
      In this review, noncontiguous epitopes in autoimmune diabetes are discussed from a historical perspective. This young yet burgeoning area of research is summarized, and the prospects and challenges that it presents are discussed. Of importance, to facilitate future pioneering discoveries in NOD mice, a long overdue summary of the conventional islet peptides recognized by T cells in this model system is also provided, accompanied by an analysis that further validates NOD mice as an important tool for the gathering of knowledge relevant to human disease.

      The NOD mouse

      The primary rodent model used for studying T1D is the NOD mouse (
      • Chen Y.G.
      • Mathews C.E.
      • Driver J.P.
      The role of NOD mice in type 1 diabetes research: Lessons from the past and recommendations for the future.
      ). First described by Makino and colleagues in 1980, the NOD mouse distinguishes itself from most other murine autoimmunity models in that disease development is spontaneous, requiring no experimental administration of disease-inciting antigens (
      • Makino S.
      • Kunimoto K.
      • Muraoka Y.
      • Mizushima Y.
      • Katagiri K.
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      Breeding of a non-obese, diabetic strain of mice.
      ). NOD mice and patients with T1D both develop lymphocytic infiltration of their islets (insulitis) and subsequent beta cell destruction mediated by T cells specific for beta cell antigens (
      • Bendelac A.
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      Syngeneic transfer of autoimmune diabetes from diabetic NOD mice to healthy neonates. Requirement for both L3T4+ and Lyt-2+ T cells.
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      • Kolb H.
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      ,
      • Miller B.J.
      • Appel M.C.
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      • Wicker L.S.
      Both the Lyt-2+ and L3T4+ T cell subsets are required for the transfer of diabetes in nonobese diabetic mice.
      ). Multiple genetic loci (referred to as Idd in mice and IDDM in humans) contribute to disease susceptibility in both NOD mice and patients with T1D (
      • Redondo M.J.
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      Genetics of type 1 diabetes.
      ,
      • Driver J.P.
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      Comparative genetics: Synergizing human and NOD mouse studies for identifying genetic causation of type 1 diabetes.
      ). Of note, in a number of cases, an Idd locus is syntenic with an IDDM one. This suggests that common pathogenic mechanisms are responsible for T1D development in both mice and humans. Indeed, in both organisms, the strongest disease link is with the occurrence of particular MHC class II alleles. Furthermore, the sole NOD class II MHC molecule H2-Ag7 and the human predisposing molecule HLA-DQ8 (a dimer of alpha chain DQA1∗03:01 and beta chain DQB1∗03:02) are structurally related and present similar peptides to CD4+ helper T cells (
      • Suri A.
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      Natural peptides selected by diabetogenic DQ8 and murine I-Ag7 molecules show common sequence specificity.
      ). These peptides are apparently critical for the initiation and/or propagation of T cell–mediated beta cell injury. The expression of certain MHC class I molecules also contributes to disease susceptibility in both NOD mice and humans (
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      • Moriwaki K.
      • et al.
      Cutting edge: Homologous recombination of the MHC class I K region defines new MHC-linked diabetogenic susceptibility gene(s) in nonobese diabetic mice.
      ,
      • Howson J.M.
      • Walker N.M.
      • Clayton D.
      • Todd J.A.
      Confirmation of HLA class II independent type 1 diabetes associations in the major histocompatibility complex including HLA-B and HLA-A.
      ,
      • Inoue K.
      • Ikegami H.
      • Fujisawa T.
      • Noso S.
      • Nojima K.
      • Babaya N.
      • Itoi-Babaya M.
      • Makimo S.
      • Ogihara T.
      Allelic variation in class I K gene as candidate for a second component of MHC-linked susceptibility to type 1 diabetes in non-obese diabetic mice.
      ,
      • Nejentsev S.
      • Howson J.M.
      • Walker N.M.
      • Szeszko J.
      • Field S.F.
      • Stevens H.E.
      • Reynolds P.
      • Hardy M.
      • King E.
      • Masters J.
      • Hulme J.
      • Maier L.M.
      • Smyth D.
      • Bailey R.
      • Cooper J.D.
      • et al.
      Localization of type 1 diabetes susceptibility to the MHC class I genes HLA-B and HLA-A.
      ,
      • Pomerleau D.P.
      • Bagley R.J.
      • Serreze D.V.
      • Mathews C.E.
      • Leiter E.H.
      Major histocompatibility complex-linked diabetes susceptibility in NOD/Lt mice: Subcongenic analysis localizes a component of Idd16 at the H2-D end of the diabetogenic H2g7 complex.
      ), again presumably due to their presentation of essential disease-related beta cell peptides to cytotoxic CD8+ T cells. These findings are consistent with the detection of beta cell–specific CD4+ and CD8+ T cells in both species (
      • Pugliese A.
      Autoreactive T cells in type 1 diabetes.
      ). Additional examples of pathogenic mechanisms shared between NOD mice and T1D-susceptible humans are alterations in the T cell–inhibitory cytotoxic T lymphocyte-associated-4 (CTLA-4) pathway (
      • Ueda H.
      • Howson J.M.
      • Esposito L.
      • Heward J.
      • Snook H.
      • Chamberlain G.
      • Rainbow D.B.
      • Hunter K.M.
      • Smith A.N.
      • Di Genova G.
      • Herr M.H.
      • Dahlman I.
      • Payne F.
      • Smyth D.
      • Lowe C.
      • et al.
      Association of the T-cell regulatory gene CTLA4 with susceptibility to autoimmune disease.
      ) and diminished function of CD4+CD25+ regulatory T cells, essential for peripheral tolerance, due to gene variants affecting interleukin 2 signaling (
      • Lowe C.E.
      • Cooper J.D.
      • Brusko T.
      • Walker N.M.
      • Smyth D.J.
      • Bailey R.
      • Bourget K.
      • Plagnol V.
      • Field S.
      • Atkinson M.
      • Clayton D.G.
      • Wicker L.S.
      • Todd J.A.
      Large-scale genetic fine mapping and genotype-phenotype associations implicate polymorphism in the IL2RA region in type 1 diabetes.
      ,
      • Vella A.
      • Cooper J.D.
      • Lowe C.E.
      • Walker N.
      • Nutland S.
      • Widmer B.
      • Jones R.
      • Ring S.M.
      • McArdle W.
      • Pembrey M.E.
      • Strachan D.P.
      • Dunger D.B.
      • Twells R.C.
      • Clayton D.G.
      • Todd J.A.
      Localization of a type 1 diabetes locus in the IL2RA/CD25 region by use of tag single-nucleotide polymorphisms.
      ,
      • Yamanouchi J.
      • Rainbow D.
      • Serra P.
      • Howlett S.
      • Hunter K.
      • Garner V.E.
      • Gonzalez-Munoz A.
      • Clark J.
      • Veijola R.
      • Cubbon R.
      • Chen S.L.
      • Rosa R.
      • Cumiskey A.M.
      • Serreze D.V.
      • Gregory S.
      • et al.
      Interleukin-2 gene variation impairs regulatory T cell function and causes autoimmunity.
      ). Thus, standard NOD mice have considerable strengths as a preclinical model.
      Although imperfections of the NOD mouse model have been noted by others (
      • Reed J.C.
      • Herold K.C.
      Thinking bedside at the bench: The NOD mouse model of T1DM.
      ), it is nonetheless true that much of what we now understand about the pathogenesis of T1D has been learned from investigation of the NOD mouse and its genetically altered derivative strains. One prime illustration of this is the utility of the NOD mouse model in the identification of human-relevant beta cell antigens, with the discovery of glucose-6-phosphatase 2 (
      • Lieberman S.M.
      • Evans A.M.
      • Han B.
      • Takaki T.
      • Vinnitskaya Y.
      • Caldwell J.A.
      • Serreze D.V.
      • Shabanowitz J.
      • Hunt D.F.
      • Nathenson S.G.
      • Santamaria P.
      • DiLorenzo T.P.
      Identification of the β cell antigen targeted by a prevalent population of pathogenic CD8+ T cells in autoimmune diabetes.
      ) and chromogranin-A being two such examples (
      • Stadinski B.D.
      • Delong T.
      • Reisdorph N.
      • Reisdorph R.
      • Powell R.L.
      • Armstrong M.
      • Piganelli J.D.
      • Barbour G.
      • Bradley B.
      • Crawford F.
      • Marrack P.
      • Mahata S.K.
      • Kappler J.W.
      • Haskins K.
      Chromogranin A is an autoantigen in type 1 diabetes.
      ). To rigorously demonstrate this point, we compiled a list of the conventional islet-derived T cell epitopes that have been reported in NOD mice. Previous reviews on this topic (
      • DiLorenzo T.P.
      • Peakman M.
      • Roep B.O.
      Translational mini-review series on type 1 diabetes: Systematic analysis of T cell epitopes in autoimmune diabetes.
      ,
      • Tsai S.
      • Shameli A.
      • Santamaria P.
      CD8+ T cells in type 1 diabetes.
      ), now greater than a decade old, were used as the foundation, with substantial updates drawn from searches of the Immune Epitope Database (www.iedb.org) (
      • Martini S.
      • Nielsen M.
      • Peters B.
      • Sette A.
      The immune epitope database and analysis resource program 2003-2018: Reflections and outlook.
      ) and PubMed, using strategies analogous to those described for human T1D-relevant epitopes (
      • James E.A.
      • Mallone R.
      • Kent S.C.
      • DiLorenzo T.P.
      T-cell epitopes and neo-epitopes in type 1 diabetes: A comprehensive update and reappraisal.
      ). These efforts yielded comprehensive lists of conventional islet-derived T cell epitopes recognized by CD4+ and CD8+ T cells in NOD mice (Tables 1 and 2, respectively). The lists include the Immune Epitope Database number for each epitope, as well as whether T cell responses were observed spontaneously (with the T cell source noted) or subsequent to peptide or protein immunization. The CD4+ T cell epitopes were derived from 18 proteins (Table 1), and the CD8+ T cell epitopes from 19 (Table 2), with ten proteins (bolded in Tables 1 and 2) contributing both CD4+ and CD8+ T cell epitopes. Taken together, conventional peptides originating from 27 discrete proteins were found to be T cell epitopes in NOD mice. By consulting a recent compilation of the islet-derived antigens recognized by T cells in humans (
      • James E.A.
      • Mallone R.
      • Kent S.C.
      • DiLorenzo T.P.
      T-cell epitopes and neo-epitopes in type 1 diabetes: A comprehensive update and reappraisal.
      ), it was determined that 56% of the antigenic mouse proteins are also sources of conventional T cell epitopes in humans (15/27, with the proteins encoded by Ins2 and INS considered a match for the purpose of this calculation). Similarly, 71% (15/21) of the islet proteins that are sources of conventional T cell epitopes in humans (
      • James E.A.
      • Mallone R.
      • Kent S.C.
      • DiLorenzo T.P.
      T-cell epitopes and neo-epitopes in type 1 diabetes: A comprehensive update and reappraisal.
      ) also yield T cell epitopes in NOD mice, with good concordance seen for both CD4+ and CD8+ T cell epitopes (Fig. 2). This analysis emphasizes the utility of NOD mice in the identification of islet antigens that translate to human T1D.
      Table 1CD4+ T cell epitopes for islet antigens in NOD mice
      Protein (gene)PositionSequenceIEDB epitope identifierMHCT cell sourceReference
      Peptide immunizationProtein immunizationSpontaneous
      Chromogranin-A (ChgA)29–42DTKVMKCVLEVISD142130Ag7YesIslets, PaLN(
      • Nikoopour E.
      • Cheung R.
      • Bellemore S.
      • Krougly O.
      • Lee-Chan E.
      • Stridsberg M.
      • Singh B.
      Vasostatin-1 antigenic epitope mapping for induction of cellular and humoral immune responses to chromogranin A autoantigen in NOD mice.
      ,
      • Nikoopour E.
      • Krougly O.
      • Lee-Chan E.
      • Haeryfar S.M.
      • Singh B.
      Detection of vasostatin-1-specific CD8+ T cells in non-obese diabetic mice that contribute to diabetes pathogenesis.
      )
      358–371WSRMDQLAKELTAE131150Ag7YesPooled islets and PaLN; spleen(
      • Stadinski B.D.
      • Delong T.
      • Reisdorph N.
      • Reisdorph R.
      • Powell R.L.
      • Armstrong M.
      • Piganelli J.D.
      • Barbour G.
      • Bradley B.
      • Crawford F.
      • Marrack P.
      • Mahata S.K.
      • Kappler J.W.
      • Haskins K.
      Chromogranin A is an autoantigen in type 1 diabetes.
      ,
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      ,
      • Nikoopour E.
      • Cheung R.
      • Bellemore S.
      • Krougly O.
      • Lee-Chan E.
      • Stridsberg M.
      • Singh B.
      Vasostatin-1 antigenic epitope mapping for induction of cellular and humoral immune responses to chromogranin A autoantigen in NOD mice.
      ,
      • Delong T.
      • Baker R.L.
      • He J.
      • Barbour G.
      • Bradley B.
      • Haskins K.
      Diabetogenic T-cell clones recognize an altered peptide of chromogranin A.
      )
      407–423RPSSREDSVEARSDFEE224951Ag7Yes(
      • Suri A.
      • Walters J.J.
      • Rohrs H.W.
      • Gross M.L.
      • Unanue E.R.
      First signature of islet β-cell-derived naturally processed peptides selected by diabetogenic class II MHC molecules.
      )
      Gamma-aminobutyric acid receptor–associated protein (Gabarap)29–45VPVIVEKAPKARIGDLD225099Ag7YesPaLN(
      • Suri A.
      • Walters J.J.
      • Rohrs H.W.
      • Gross M.L.
      • Unanue E.R.
      First signature of islet β-cell-derived naturally processed peptides selected by diabetogenic class II MHC molecules.
      )
      Glial fibrillary acidic protein (Gfap)51–65LAGALNAGFKETRAS106588Ag7Yes(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      96–110AELNQLRAKEPTKLA106229Ag7YesYesSpleen(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      106–120PTKLADVYQAELREL106718Ag7Yes(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      116–130ELRELRLRLDQLTAN106393Ag7YesYesSpleen(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      206–220RELREQLAQQQVHVE106769Ag7Yes(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      216–230QVHVEMDVAKPDLTA106753Ag7YesYesSpleen(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      241–255AVATSNMQETEEWYR106285Ag7Yes(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      331–345EGQSLKEEMARHLQE106382Ag7Yes(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      Glucose-6-phosphatase 2 (G6pc2)4–22LHRSGVLIIHHLQEDYRTY104553Ag7YesSpleen(
      • Mukherjee R.
      • Wagar D.
      • Stephens T.A.
      • Lee-Chan E.
      • Singh B.
      Identification of CD4+ T cell-specific epitopes of islet-specific glucose-6-phosphatase catalytic subunit-related protein: A novel β cell autoantigen in type 1 diabetes.
      )
      17–34EDYRTYYGFLNFMSNVGD178720Ag7Yes(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      55–72TKMIWVAVIGDWFNLIFK179568Ag7YesPaLN(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      123–145WYVMVTAALSYTISRMEESSVTL104688Ag7YesSpleen(
      • Mukherjee R.
      • Wagar D.
      • Stephens T.A.
      • Lee-Chan E.
      • Singh B.
      Identification of CD4+ T cell-specific epitopes of islet-specific glucose-6-phosphatase catalytic subunit-related protein: A novel β cell autoantigen in type 1 diabetes.
      )
      125–142VMVTAALSYTISRMEESS179653Ag7Yes(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      128–145TAALSYTISRMEESSVTL104646Ag7YesSpleen(
      • Mukherjee R.
      • Wagar D.
      • Stephens T.A.
      • Lee-Chan E.
      • Singh B.
      Identification of CD4+ T cell-specific epitopes of islet-specific glucose-6-phosphatase catalytic subunit-related protein: A novel β cell autoantigen in type 1 diabetes.
      )
      141–156SSVTLHRLTWSFLWSV179534Ag7Yes(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      179–196VILGVIGGMLVAEAFEHT179631Ag7Yes(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      195–214HTPGVHMASLSVYLKTNVFL104519Ag7YesSpleen(
      • Mukherjee R.
      • Wagar D.
      • Stephens T.A.
      • Lee-Chan E.
      • Singh B.
      Identification of CD4+ T cell-specific epitopes of islet-specific glucose-6-phosphatase catalytic subunit-related protein: A novel β cell autoantigen in type 1 diabetes.
      )
      241–256KWCANPDWIHIDSTPF179108Ag7Yes(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      271–288FAINSEMFLRSCQGENGT178790Ag7YesPaLN(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      301–318LTTMQLYRFIKIPTHAEP179219Ag7YesPaLN(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      309–326FIKIPTHAEPLFYLLSFC178817Ag7YesPaLN(
      • Yang T.
      • Hohenstein A.C.
      • Lee C.E.
      • Hutton J.C.
      • Davidson H.W.
      Mapping I-Ag7 restricted epitopes in murine G6PC2.
      )
      Glutamate decarboxylase 1 (Gad1)29–48DTWCGVAHGCTRKLGLKICG104757Ag7YesSpleen(
      • Zechel M.A.
      • Elliott J.F.
      • Atkinson M.A.
      • Singh B.
      Characterization of novel T-cell epitopes on 65 kDa and 67 kDa glutamic acid decarboxylase relevant in autoimmune responses in NOD mice.
      )
      44–62LKICGFLQRTNSLEEKSRL104883Ag7YesSpleen(
      • Zechel M.A.
      • Elliott J.F.
      • Atkinson M.A.
      • Singh B.
      Characterization of novel T-cell epitopes on 65 kDa and 67 kDa glutamic acid decarboxylase relevant in autoimmune responses in NOD mice.
      )
      Glutamate decarboxylase 2 (Gad2)118–128LLQYVVKSFDR104044Ag7Yes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      202–221TNMFTYEIAPVFVLLEYVTL105004Ag7YesYesSpleen(
      • Zechel M.A.
      • Elliott J.F.
      • Atkinson M.A.
      • Singh B.
      Characterization of novel T-cell epitopes on 65 kDa and 67 kDa glutamic acid decarboxylase relevant in autoimmune responses in NOD mice.
      )
      206–220TYEIAPVFVLLEYVT67328Ag7YesYes(
      • Liu C.P.
      • Jiang K.
      • Wu C.H.
      • Lee W.H.
      • Lin W.J.
      Detection of glutamic acid decarboxylase-activated T cells with I-Ag7 tetramers.
      ,
      • Chao C.C.
      • Sytwu H.K.
      • Chen E.L.
      • Toma J.
      • McDevitt H.O.
      The role of MHC class II molecules in susceptibility to type I diabetes: Identification of peptide epitopes and characterization of the T cell repertoire.
      )
      208–217EIAPVFVLLE103138Ag7Yes(
      • Murray J.S.
      • Oney S.
      • Page J.E.
      • Kratochvil-Stava A.
      • Hu Y.
      • Makagiansar I.T.
      • Brown J.C.
      • Kobayashi N.
      • Siahaan T.J.
      Suppression of type 1 diabetes in NOD mice by bifunctional peptide inhibitor: Modulation of the immunological synapse formation.
      )
      217–236EYVTLKKMREIIGWPGGSGD104481Ag7YesYesIslets, PaLN, spleen(
      • Zechel M.A.
      • Elliott J.F.
      • Atkinson M.A.
      • Singh B.
      Characterization of novel T-cell epitopes on 65 kDa and 67 kDa glutamic acid decarboxylase relevant in autoimmune responses in NOD mice.
      ,
      • Li L.
      • Wang B.
      • Frelinger J.A.
      • Tisch R.
      T-cell promiscuity in autoimmune diabetes.
      )
      221–235LKKMREIIGWPGGSG102615Ag7YesYes(
      • Chao C.C.
      • Sytwu H.K.
      • Chen E.L.
      • Toma J.
      • McDevitt H.O.
      The role of MHC class II molecules in susceptibility to type I diabetes: Identification of peptide epitopes and characterization of the T cell repertoire.
      ,
      • Chen C.
      • Lee W.H.
      • Yun P.
      • Snow P.
      • Liu C.P.
      Induction of autoantigen-specific Th2 and Tr1 regulatory T cells and modulation of autoimmune diabetes.
      )
      232–251GGSGDGIFSPGGAISNMYAM105216Ag7Spleen(
      • Li L.
      • Wang B.
      • Frelinger J.A.
      • Tisch R.
      T-cell promiscuity in autoimmune diabetes.
      )
      247–266NMYAMLIARYKMSPEVKEKG102680Ag7YesSpleen(
      • Kaufman D.L.
      • Clare-Salzler M.
      • Tian J.
      • Forsthuber T.
      • Ting G.S.
      • Robinson P.
      • Atkinson M.A.
      • Sercarz E.E.
      • Tobin A.J.
      • Lehmann P.V.
      Spontaneous loss of T-cell tolerance to glutamic acid decarboxylase in murine insulin-dependent diabetes.
      ,
      • Ravanan R.
      • Wong S.F.
      • Morgan N.G.
      • Mathieson P.W.
      • Smith R.M.
      Inhalation of glutamic acid decarboxylase 65-derived peptides can protect against recurrent autoimmune but not alloimmune responses in the non-obese diabetic mouse.
      )
      268–278AAVPRLIAFTS103782Ag7Yes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      286–300KKGAAALGIGTDSVI102562Ag7YesYes(
      • Chao C.C.
      • Sytwu H.K.
      • Chen E.L.
      • Toma J.
      • McDevitt H.O.
      The role of MHC class II molecules in susceptibility to type I diabetes: Identification of peptide epitopes and characterization of the T cell repertoire.
      ,
      • Postigo-Fernandez J.
      • Creusot R.J.
      A multi-epitope DNA vaccine enables a broad engagement of diabetogenic T cells for tolerance in type 1 diabetes.
      )
      290–309AALGIGTDSVILIKCDERGK104403Ag7YesIslets, PaLN, spleen(
      • Li L.
      • Wang B.
      • Frelinger J.A.
      • Tisch R.
      T-cell promiscuity in autoimmune diabetes.
      ,
      • Tisch R.
      • Wang B.
      • Serreze D.V.
      Induction of glutamic acid decarboxylase 65-specific Th2 cells and suppression of autoimmune diabetes at late stages of disease is epitope dependent.
      )
      316–335ERRILEVKQKGFVPFLVSAT104477Ag7Spleen(
      • Ogino T.
      • Sato K.
      • Miyokawa N.
      • Kimura S.
      • Katagiri M.
      Importance of GAD65 peptides and I-Ag7 in the development of insulitis in nonobese diabetic mice.
      )
      401–415PLQCSALLVREEGLM104599Ag7Yes(
      • Chao C.C.
      • Sytwu H.K.
      • Chen E.L.
      • Toma J.
      • McDevitt H.O.
      The role of MHC class II molecules in susceptibility to type I diabetes: Identification of peptide epitopes and characterization of the T cell repertoire.
      )
      509–524VPPSLRTLEDNEERMS104672Ag7Spleen(
      • Xu X.J.
      • Gearon C.
      • Stevens E.
      • Vergani D.
      • Baum H.
      • Peakman M.
      Spontaneous T-cell proliferation in the non-obese diabetic mouse to a peptide from the unique class II MHC molecule, I-Ag7, which is also protective against the development of autoimmune diabetes.
      )
      509–528VPPSLRTLEDNEERMSRLSK102913Ag7YesYesSpleen(
      • Kaufman D.L.
      • Clare-Salzler M.
      • Tian J.
      • Forsthuber T.
      • Ting G.S.
      • Robinson P.
      • Atkinson M.A.
      • Sercarz E.E.
      • Tobin A.J.
      • Lehmann P.V.
      Spontaneous loss of T-cell tolerance to glutamic acid decarboxylase in murine insulin-dependent diabetes.
      ,
      • Ravanan R.
      • Wong S.F.
      • Morgan N.G.
      • Mathieson P.W.
      • Smith R.M.
      Inhalation of glutamic acid decarboxylase 65-derived peptides can protect against recurrent autoimmune but not alloimmune responses in the non-obese diabetic mouse.
      ,
      • Han G.
      • Li Y.
      • Wang J.
      • Wang R.
      • Chen G.
      • Song L.
      • Xu R.
      • Yu M.
      • Wu X.
      • Qian J.
      • Shen B.
      Active tolerance induction and prevention of autoimmune diabetes by immunogene therapy using recombinant adenoassociated virus expressing glutamic acid decarboxylase 65 peptide GAD500-585.
      )
      524–538SRLSKVAPVIKARMM60728Ag7Spleen(
      • Chen G.
      • Han G.
      • Feng J.
      • Wang J.
      • Wang R.
      • Xu R.
      • Shen B.
      • Qian J.
      • Li Y.
      Glutamic acid decarboxylase-derived epitopes with specific domains expand CD4+CD25+ regulatory T cells.
      ,
      • Quinn A.
      • McInerney B.
      • Reich E.P.
      • Kim O.
      • Jensen K.P.
      • Sercarz E.E.
      Regulatory and effector CD4 T cells in nonobese diabetic mice recognize overlapping determinants on glutamic acid decarboxylase and use distinct Vβ genes.
      )
      524–543SRLSKVAPVIKARMMEYGTT102085Ag7YesYesSpleen(
      • Liu C.P.
      • Jiang K.
      • Wu C.H.
      • Lee W.H.
      • Lin W.J.
      Detection of glutamic acid decarboxylase-activated T cells with I-Ag7 tetramers.
      ,
      • Kaufman D.L.
      • Clare-Salzler M.
      • Tian J.
      • Forsthuber T.
      • Ting G.S.
      • Robinson P.
      • Atkinson M.A.
      • Sercarz E.E.
      • Tobin A.J.
      • Lehmann P.V.
      Spontaneous loss of T-cell tolerance to glutamic acid decarboxylase in murine insulin-dependent diabetes.
      ,
      • Zekzer D.
      • Wong F.S.
      • Ayalon O.
      • Millet I.
      • Altieri M.
      • Shintani S.
      • Solimena M.
      • Sherwin R.S.
      GAD-reactive CD4+ Th1 cells induce diabetes in NOD/SCID mice.
      )
      530–543APVIKARMMEYGTT103810Ag7YesSpleen(
      • Quinn A.
      • McInerney B.
      • Reich E.P.
      • Kim O.
      • Jensen K.P.
      • Sercarz E.E.
      Regulatory and effector CD4 T cells in nonobese diabetic mice recognize overlapping determinants on glutamic acid decarboxylase and use distinct Vβ genes.
      )
      531–545PVIKARMMEYGTTMV104605Ag7Spleen(
      • Ogino T.
      • Sato K.
      • Miyokawa N.
      • Kimura S.
      • Katagiri M.
      Importance of GAD65 peptides and I-Ag7 in the development of insulitis in nonobese diabetic mice.
      )
      561–575ISNPAATHQDIDFLI104845Ag7YesSpleen(
      • Chao C.C.
      • Sytwu H.K.
      • Chen E.L.
      • Toma J.
      • McDevitt H.O.
      The role of MHC class II molecules in susceptibility to type I diabetes: Identification of peptide epitopes and characterization of the T cell repertoire.
      ,
      • Li L.
      • Wang B.
      • Frelinger J.A.
      • Tisch R.
      T-cell promiscuity in autoimmune diabetes.
      )
      571–585IDFLIEEIERLGQDL102525Ag7Yes(
      • Chao C.C.
      • McDevitt H.O.
      Identification of immunogenic epitopes of GAD 65 presented by Ag7 in non-obese diabetic mice.
      )
      60-kDa heat shock protein, mitochondrial (Hspd1)76–95DGVTVAKSIDLKDKYKNIGA102353Ag7Yes(
      • Bockova J.
      • Elias D.
      • Cohen I.R.
      Treatment of NOD diabetes with a novel peptide of the hsp60 molecule induces Th2-type antibodies.
      )
      166–185EEIAQVATISANGDKDIGNI102381Ag7Yes(
      • Bockova J.
      • Elias D.
      • Cohen I.R.
      Treatment of NOD diabetes with a novel peptide of the hsp60 molecule induces Th2-type antibodies.
      )
      195–214RKGVITVKDGKTLNDELEII102765Ag7Yes(
      • Bockova J.
      • Elias D.
      • Cohen I.R.
      Treatment of NOD diabetes with a novel peptide of the hsp60 molecule induces Th2-type antibodies.
      )
      361–380KGDKAHIEKRIQEITEQLDI103303Ag7Yes(
      • Bockova J.
      • Elias D.
      • Cohen I.R.
      Treatment of NOD diabetes with a novel peptide of the hsp60 molecule induces Th2-type antibodies.
      )
      437–460VLGGGCALLRCIPALDSLKPANED105025Ag7Spleen(
      • Birk O.S.
      • Elias D.
      • Weiss A.S.
      • Rosen A.
      • van-der Zee R.
      • Walker M.D.
      • Cohen I.R.
      NOD mouse diabetes: The ubiquitous mouse hsp60 is a β-cell target antigen of autoimmune T cells.
      )
      526–545RTALLDAAGVASLLTTAEAV103572Ag7Yes(
      • Bockova J.
      • Elias D.
      • Cohen I.R.
      Treatment of NOD diabetes with a novel peptide of the hsp60 molecule induces Th2-type antibodies.
      )
      541–560TAEAVVTEIPKEEKDPGMGA103630Ag7Yes(
      • Bockova J.
      • Elias D.
      • Cohen I.R.
      Treatment of NOD diabetes with a novel peptide of the hsp60 molecule induces Th2-type antibodies.
      )
      Insulin-1 (Ins1)7–23FLPLLALLALWEPKPTQ105786Ag7Yes(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      )
      7–24FLPLLALLALWEPKPTQA133571Ag7YesIslets(
      • Arai T.
      • Moriyama H.
      • Shimizu M.
      • Sasaki H.
      • Kishi M.
      • Okumachi Y.
      • Yasuda H.
      • Hara K.
      • Yokono K.
      • Nagata M.
      Administration of a determinant of preproinsulin can induce regulatory T cells and suppress anti-islet autoimmunity in NOD mice.
      )
      20–35KPTQAFVKQHLCGPHL105906Ag7Yes(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      )
      33–47PHLVEALYLVCGERG104594Ag7YesIslets(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      ,
      • Daniel D.
      • Gill R.G.
      • Schloot N.
      • Wegmann D.
      Epitope specificity, cytokine production profile and diabetogenic activity of insulin-specific T cell clones isolated from NOD mice.
      )
      34–53HLVEALYLVCGERGFFYTPK105241Ag7Yes(
      • Heath V.L.
      • Hutchings P.
      • Fowell D.J.
      • Cooke A.
      • Mason D.W.
      Peptides derived from murine insulin are diabetogenic in both rats and mice, but the disease-inducing epitopes are different: Evidence against a common environmental cross-reactivity in the pathogenicity of type 1 diabetes.
      )
      36–44VEALYLVCG104666Ag7Pooled islets and PaLN(
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      )
      37–47EALYLVCGERG104759Ag7Islets(
      • Abiru N.
      • Wegmann D.
      • Kawasaki E.
      • Gottlieb P.
      • Simone E.
      • Eisenbarth G.S.
      Dual overlapping peptides recognized by insulin peptide B:9-23 T cell receptor AV13S3 T cell clones of the NOD mouse.
      )
      57–85EVEDPQVEQLELGGSPGDLQTLA

      LEVARQ
      Ag7Pooled islets and PaLN(
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      )
      61–85PQVEQLELGGSPGDLQTLALEV

      ARQ
      Ag7Pooled islets and PaLN(
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      )
      71–86SPGDLQTLALEVARQK106117Ag7YesIslets(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      )
      71–88SPGDLQTLALEVARQKRG104984Ag7YesPaLN(
      • Levisetti M.G.
      • Lewis D.M.
      • Suri A.
      • Unanue E.R.
      Weak proinsulin peptide-major histocompatibility complexes are targeted in autoimmune diabetes in mice.
      )
      73–87GDLQTLALEVARQKRAg7Yes(
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      )
      75–85LQTLALEVARQAg7Pooled islets and PaLN(
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      )
      77–92TLALEVARQKRGIVDQ106141Ag7Yes(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      )
      94–108CTSICSLYQLENYCN102341Ag7Islets(
      • Daniel D.
      • Wegmann D.R.
      Protection of nonobese diabetic mice from diabetes by intranasal or subcutaneous administration of insulin peptide B-(9-23).
      )
      Insulin-2 (Ins2)14–30LFLWESHPTQAFVKQHL105927Ag7Yes(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      )
      20–35HPTQAFVKQHLCGSHL105866Ag7Yes(
      • Thebault-Baumont K.
      • Dubois-Laforgue D.
      • Krief P.
      • Briand J.P.
      • Halbout P.
      • Vallon-Geoffroy K.
      • Morin J.
      • Laloux V.
      • Lehuen A.
      • Carel J.C.
      • Jami J.
      • Muller S.
      • Boitard C.
      Acceleration of type 1 diabetes mellitus in proinsulin 2-deficient NOD mice.
      )
      26–41VKQHLCGSHLVEALYL106166Ag7Islets(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      )
      33–40SHLVEALY104977Ag7Islets(
      • Abiru N.
      • Wegmann D.
      • Kawasaki E.
      • Gottlieb P.
      • Simone E.
      • Eisenbarth G.S.
      Dual overlapping peptides recognized by insulin peptide B:9-23 T cell receptor AV13S3 T cell clones of the NOD mouse.
      )
      33–47SHLVEALYLVCGERG58388Ag7YesIslets, spleen(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      ,
      • Daniel D.
      • Gill R.G.
      • Schloot N.
      • Wegmann D.
      Epitope specificity, cytokine production profile and diabetogenic activity of insulin-specific T cell clones isolated from NOD mice.
      ,
      • Michels A.W.
      • Ostrov D.A.
      • Zhang L.
      • Nakayama M.
      • Fuse M.
      • McDaniel K.
      • Roep B.O.
      • Gottlieb P.A.
      • Atkinson M.A.
      • Eisenbarth G.S.
      Structure-based selection of small molecules to alter allele-specific MHC class II antigen presentation.
      )
      36–44VEALYLVCG104666Ag7Pooled islets and PaLN(
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      )
      37–47EALYLVCGERG104759Ag7Islets(
      • Abiru N.
      • Wegmann D.
      • Kawasaki E.
      • Gottlieb P.
      • Simone E.
      • Eisenbarth G.S.
      Dual overlapping peptides recognized by insulin peptide B:9-23 T cell receptor AV13S3 T cell clones of the NOD mouse.
      )
      48–57FFYTPMSRRE106415Ag7YesPaLN, spleen(
      • Chen W.
      • Bergerot I.
      • Elliott J.F.
      • Harrison L.C.
      • Abiru N.
      • Eisenbarth G.S.
      • Delovitch T.L.
      Evidence that a peptide spanning the B-C junction of proinsulin is an early autoantigen epitope in the pathogenesis of type 1 diabetes.
      )
      48–60FFYTPMSRREVED102425Ag7Islets(
      • Spence A.
      • Purtha W.
      • Tam J.
      • Dong S.
      • Kim Y.
      • Ju C.H.
      • Sterling T.
      • Nakayama M.
      • Robinson W.H.
      • Bluestone J.A.
      • Anderson M.S.
      • Tang Q.
      Revealing the specificity of regulatory T cells in murine autoimmune diabetes.
      )
      71–88GPGAGDLQTLALEVAQQK105842Ag7Yes(
      • Halbout P.
      • Briand J.P.
      • Becourt C.
      • Muller S.
      • Boitard C.
      T cell response to preproinsulin I and II in the nonobese diabetic mouse.
      )
      96–110CTSICSLYQLENYCN102341Ag7Islets(
      • Daniel D.
      • Wegmann D.R.
      Protection of nonobese diabetic mice from diabetes by intranasal or subcutaneous administration of insulin peptide B-(9-23).
      )
      Islet amyloid polypeptide (Iapp)38–57KCNTATCATQRLANFLVRSS189990Ag7Islets(
      • Baker R.L.
      • Delong T.
      • Barbour G.
      • Bradley B.
      • Nakayama M.
      • Haskins K.
      Cutting edge: CD4 T cells reactive to an islet amyloid polypeptide peptide accumulate in the pancreas and contribute to disease pathogenesis in nonobese diabetic mice.
      ,
      • Delong T.
      • Baker R.L.
      • Reisdorph N.
      • Reisdorph R.
      • Powell R.L.
      • Armstrong M.
      • Barbour G.
      • Bradley B.
      • Haskins K.
      Islet amyloid polypeptide is a target antigen for diabetogenic CD4+ T cells.
      )
      78–90NAARDPNRESLDFAg7Pooled islets and PaLN(
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      )
      Islet cell autoantigen 1 (Ica1)35–46AFIKATGKKEDE104413Ag7YesYesSpleen(
      • Karges W.
      • Hammond-McKibben D.
      • Gaedigk R.
      • Shibuya N.
      • Cheung R.
      • Dosch H.M.
      Loss of self-tolerance to ICA69 in nonobese diabetic mice.
      )
      Lithostathine-2 (Reg2)44–63PEGANAYGSYCYYLIEDRLT226248Ag7Yes(
      • Gurr W.
      • Shaw M.
      • Herzog R.I.
      • Li Y.
      • Sherwin R.
      Vaccination with single chain antigen receptors for islet-derived peptides presented on I-Ag7 delays diabetes in NOD mice by inducing anergy in self-reactiveT-cells.
      )
      48–64NAYGSYCYYLIEDRLTW226242Ag7PaLN(
      • Gurr W.
      • Shaw M.
      • Herzog R.I.
      • Li Y.
      • Sherwin R.
      Vaccination with single chain antigen receptors for islet-derived peptides presented on I-Ag7 delays diabetes in NOD mice by inducing anergy in self-reactiveT-cells.
      )
      Receptor-type tyrosine-protein phosphatase-like N (Ptprn)676–693PSWCEEPAQANMDISTGH104939Ag7Yes(
      • Kudva Y.C.
      • Deng Y.J.
      • Govindarajan R.
      • Abraham R.S.
      • Marietta E.V.
      • Notkins A.L.
      • David C.S.
      HLA-DQ8 transgenic and NOD mice recognize different epitopes within the cytoplasmic region of the tyrosine phosphatase-like molecule, IA-2.
      )
      691–708TGHMILAYMEDHLRNRDR104999Ag7Yes(
      • Kudva Y.C.
      • Deng Y.J.
      • Govindarajan R.
      • Abraham R.S.
      • Marietta E.V.
      • Notkins A.L.
      • David C.S.
      HLA-DQ8 transgenic and NOD mice recognize different epitopes within the cytoplasmic region of the tyrosine phosphatase-like molecule, IA-2.
      )
      706–723RDRLAKEWQALCAYQAEP104959Ag7Yes(
      • Kudva Y.C.
      • Deng Y.J.
      • Govindarajan R.
      • Abraham R.S.
      • Marietta E.V.
      • Notkins A.L.
      • David C.S.
      HLA-DQ8 transgenic and NOD mice recognize different epitopes within the cytoplasmic region of the tyrosine phosphatase-like molecule, IA-2.
      )
      751–768IKLKVESSPSRSDYINAS104838Ag7Yes(
      • Kudva Y.C.
      • Deng Y.J.
      • Govindarajan R.
      • Abraham R.S.
      • Marietta E.V.
      • Notkins A.L.
      • David C.S.
      HLA-DQ8 transgenic and NOD mice recognize different epitopes within the cytoplasmic region of the tyrosine phosphatase-like molecule, IA-2.
      )
      766–783NASPIIEHDPRMPAYIAT104909Ag7Yes(
      • Kudva Y.C.
      • Deng Y.J.
      • Govindarajan R.
      • Abraham R.S.
      • Marietta E.V.
      • Notkins A.L.
      • David C.S.
      HLA-DQ8 transgenic and NOD mice recognize different epitopes within the cytoplasmic region of the tyrosine phosphatase-like molecule, IA-2.
      )
      781–798IATQGPLSHTIADFWQMV104836Ag7Yes(
      • Kudva Y.C.
      • Deng Y.J.
      • Govindarajan R.
      • Abraham R.S.
      • Marietta E.V.
      • Notkins A.L.
      • David C.S.
      HLA-DQ8 transgenic and NOD mice recognize different epitopes within the cytoplasmic region of the tyrosine phosphatase-like molecule, IA-2.
      )
      961–979FALTAVAEEVNAILKALPQ104772Ag7Yes(
      • Kudva Y.C.
      • Deng Y.J.
      • Govindarajan R.
      • Abraham R.S.
      • Marietta E.V.
      • Notkins A.L.
      • David C.S.
      HLA-DQ8 transgenic and NOD mice recognize different epitopes within the cytoplasmic region of the tyrosine phosphatase-like molecule, IA-2.
      )
      Receptor-type tyrosine-protein phosphatase N2 (Ptprn2)636–655KLSGLGADPSADATEAYQEL104857Ag7Yes(
      • Kelemen K.
      • Wegmann D.R.
      • Hutton J.C.
      T-cell epitope analysis on the autoantigen phogrin (IA-2β) in the nonobese diabetic mouse.
      )
      Secretogranin-2 (Scg2)234–248DVYKTNNIAYEDVVG224671Ag7Yes(
      • Suri A.
      • Walters J.J.
      • Rohrs H.W.
      • Gross M.L.
      • Unanue E.R.
      First signature of islet β-cell-derived naturally processed peptides selected by diabetogenic class II MHC molecules.
      )
      Secretogranin-3 (Scg3)229–244IPEKVTPVAAVQDGFT224790Ag7YesPaLN(
      • Suri A.
      • Walters J.J.
      • Rohrs H.W.
      • Gross M.L.
      • Unanue E.R.
      First signature of islet β-cell-derived naturally processed peptides selected by diabetogenic class II MHC molecules.
      )
      Synapse-associated protein 1 (Syap1)262–279TPPVVIKSQLKSQEDEEE225035Ag7PaLN(
      • Suri A.
      • Walters J.J.
      • Rohrs H.W.
      • Gross M.L.
      • Unanue E.R.
      First signature of islet β-cell-derived naturally processed peptides selected by diabetogenic class II MHC molecules.
      )
      Zinc transporter 8 (Slc30a8)212–225SVRAAFVHALGDVF232569Ag7Yes(
      • Nayak D.K.
      • Calderon B.
      • Vomund A.N.
      • Unanue E.R.
      ZnT8-reactive T cells are weakly pathogenic in NOD mice but can participate in diabetes under inflammatory conditions.
      )
      313–326ILSVHVATAASQDS110292Ag7YesPooled islets and PaLN(
      • Wan X.
      • Vomund A.N.
      • Peterson O.J.
      • Chervonsky A.V.
      • Lichti C.F.
      • Unanue E.R.
      The MHC-II peptidome of pancreatic islets identifies key features of autoimmune peptides.
      ,
      • Nayak D.K.
      • Calderon B.
      • Vomund A.N.
      • Unanue E.R.
      ZnT8-reactive T cells are weakly pathogenic in NOD mice but can participate in diabetes under inflammatory conditions.
      )
      330–344RTGIAQALSSFDLHS232561Ag7YesYes(
      • Nayak D.K.
      • Calderon B.
      • Vomund A.N.
      • Unanue E.R.
      ZnT8-reactive T cells are weakly pathogenic in NOD mice but can participate in diabetes under inflammatory conditions.
      )
      345–359LTIQIESAADQDPSC232549Ag7YesYes(
      • Nayak D.K.
      • Calderon B.
      • Vomund A.N.
      • Unanue E.R.
      ZnT8-reactive T cells are weakly pathogenic in NOD mice but can participate in diabetes under inflammatory conditions.
      )
      Proteins in bold contribute both CD4+ and CD8+ T cell epitopes.
      Abbreviations: IEDB, Immune Epitope Database; PaLN, pancreatic lymph node.
      Table 2CD8+ T cell epitopes for islet antigens in NOD mice
      Protein (gene)PositionSequenceIEDB epitope identifierMHCT cell sourceReference
      Peptide immunizationProtein immunizationSpontaneous
      ATP-binding cassette subfamily C member 8 (Abcc8)229–237TYWWMNAFI1311101KdIslets(
      • Mukherjee G.
      • Chaparro R.J.
      • Schloss J.
      • Smith C.
      • Bando C.D.
      • DiLorenzo T.P.
      Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice.
      )
      Chromogranin-A (ChgA)36–44VLEVISDSL142326KdYesIslets, PaLN(
      • Nikoopour E.
      • Krougly O.
      • Lee-Chan E.
      • Haeryfar S.M.
      • Singh B.
      Detection of vasostatin-1-specific CD8+ T cells in non-obese diabetic mice that contribute to diabetes pathogenesis.
      )
      265–273HFHAGYKAI1311038KdIslets(
      • Mukherjee G.
      • Chaparro R.J.
      • Schloss J.
      • Smith C.
      • Bando C.D.
      • DiLorenzo T.P.
      Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice.
      )
      438–446QELESLSAI1311072KdIslets(
      • Mukherjee G.
      • Chaparro R.J.
      • Schloss J.
      • Smith C.
      • Bando C.D.
      • DiLorenzo T.P.
      Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice.
      )
      Dopamine beta-hydroxylase (Dbh)233–241TYWCYITEL546779KdPaLN, spleen(
      • Yu C.
      • Burns J.C.
      • Robinson W.H.
      • Utz P.J.
      • Ho P.P.
      • Steinman L.
      • Frey A.B.
      Identification of candidate tolerogenic CD8+ T cell epitopes for therapy of type 1 diabetes in the NOD mouse model.
      )
      Glial fibrillary acidic protein (Gfap)79–87SYIEKVRFL106886KdYesSpleen(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      253–261WYRSKFADL107000KdYesSpleen(
      • Tsui H.
      • Chan Y.
      • Tang L.
      • Winer S.
      • Cheung R.K.
      • Paltser G.
      • Selvanantham T.
      • Elford A.R.
      • Ellis J.R.
      • Becker D.J.
      • Ohashi P.S.
      • Dosch H.M.
      Targeting of pancreatic glia in type 1 diabetes.
      )
      Glucose-6-phosphatase 2 (G6pc2)2–10DFLHRSGVL105134KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      3–11FLHRSGVLI105188DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      18–26DYRTYYGFL105157KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      21–29TYYGFLNFM105560KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      33–41GDPRNIFSI105208DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      41–49IYFPLWFQL105257KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      48–56QLNQNVGTK105486DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      50–58NQNVGTKMI105411DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      66–74WFNLIFKWI105587KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      89–97IYPNHSSPC105258KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      90–98YPNHSSPCL105619DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      114–122GHAMGSSCV105217DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      130–138ALSYTISRM105099DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      133–141YTISRMEES105622DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      136–144SRMEESSVT105527DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      137–145RMEESSVTL105500DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      140–148ESSVTLHRL105171DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      154–162WSVFWLIQI105609DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      156–164VFWLIQISV105569KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      167–175SRVFIATHF105528DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      172–180ATHFPHQVI105106DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      173–181THFPHQVIL105544DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      193–201FEHTPGVHM105181DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      204–212LSVYLKTNV105312KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      206–214VYLKTNVFL102926KdBlood, islets, PaLN, spleen(
      • Lieberman S.M.
      • Evans A.M.
      • Han B.
      • Takaki T.
      • Vinnitskaya Y.
      • Caldwell J.A.
      • Serreze D.V.
      • Shabanowitz J.
      • Hunt D.F.
      • Nathenson S.G.
      • Santamaria P.
      • DiLorenzo T.P.
      Identification of the β cell antigen targeted by a prevalent population of pathogenic CD8+ T cells in autoimmune diabetes.
      ,
      • Yu C.
      • Burns J.C.
      • Robinson W.H.
      • Utz P.J.
      • Ho P.P.
      • Steinman L.
      • Frey A.B.
      Identification of candidate tolerogenic CD8+ T cell epitopes for therapy of type 1 diabetes in the NOD mouse model.
      ,
      • Marino E.
      • Tan B.
      • Binge L.
      • Mackay C.R.
      • Grey S.T.
      B-cell cross-presentation of autologous antigen precipitates diabetes.
      )
      219–227LGFYLLLRL105290DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      225–233LRLFGIDLL105308DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      241–249KWCANPDWI105272DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      243–251CANPDWIHI105117DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      258–266GLVRNLGVL105229DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      269–277LGFAINSEM105289DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      270–278GFAINSEMF105210DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      271–279FAINSEMFL105175DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      282–290CQGENGTKP105123DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      287–295GTKPSFRLL105233DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      296–304CALTSLTTM105116DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      298–306LTSLTTMQL105316DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      299–307TSLTTMQLY105554DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      304–312MQLYRFIKI105343DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      308–316RFIKIPTHA105495KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      311–319KIPTHAEPL105262DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      314–322THAEPLFYL105543DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      315–323HAEPLFYLL105235KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      323–331LSFCKSASI105310DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      324–332SFCKSASIP105516KdIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      326–334CKSASIPLM105121DbIslets(
      • Han B.
      • Serra P.
      • Amrani A.
      • Yamanouchi J.
      • Maree A.F.
      • Edelstein-Keshet L.
      • Santamaria P.
      Prevention of diabetes by manipulation of anti-IGRP autoimmunity: High efficiency of a low-affinity peptide.
      )
      Glutamate decarboxylase 1 (Gad1)515–524WYIPQSLRGV104687KdYes(
      • Bowie L.
      • Tite J.
      • Cooke A.
      Generation and maintenance of autoantigen-specific CD8+ T cell clones isolated from NOD mice.
      )
      Glutamate decarboxylase 2 (Gad2)85–95GDVNYAFLHAT103916KdYes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      88–98NYAFLHATDLL104162KdYes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      90–98AFLHATDLL104414KdYesPaLN, spleen(
      • Severe S.
      • Gauvrit A.
      • Vu A.T.
      • Bach J.M.
      CD8+ T lymphocytes specific for glutamic acid decarboxylase 90-98 epitope mediate diabetes in NODSCID mouse.
      )
      118–128LLQYVVKSFDR104044KdYes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      124–134KSFDRSTKVID104015KdYes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      136–146HYPNELLQEYN103979KdYes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      139–149NELLQEYNWEL104145KdYes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      178–186YFNQLSTGL104689KdPaLN, spleen(
      • Yu C.
      • Burns J.C.
      • Robinson W.H.
      • Utz P.J.
      • Ho P.P.
      • Steinman L.
      • Frey A.B.
      Identification of candidate tolerogenic CD8+ T cell epitopes for therapy of type 1 diabetes in the NOD mouse model.
      )
      206–214TYEIAPVFV104661KdYesSpleen(
      • Quinn A.
      • McInerney M.F.
      • Sercarz E.E.
      MHC class I-restricted determinants on the glutamic acid decarboxylase 65 molecule induce spontaneous CTL activity.
      )
      268–278AAVPRLIAFTS103782KdYes(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      507–516WFVPPSLRTL1123568KdYes(
      • Videbaek N.
      • Harach S.
      • Phillips J.
      • Hutchings P.
      • Ozegbe P.
      • Michelsen B.K.
      • Cooke A.
      An islet-homing NOD CD8+ cytotoxic T cell clone recognizes GAD65 and causes insulitis.
      )
      544–554MVSYQPLGDKV104138KdYesSpleen(
      • Busick R.Y.
      • Aguilera C.
      • Quinn A.
      Dominant CTL-inducing epitopes on GAD65 are adjacent to or overlap with dominant Th-inducing epitopes.
      )
      546–554SYQPLGDKV104294KdYesPaLN, spleen(
      • Severe S.
      • Gauvrit A.
      • Vu A.T.
      • Bach J.M.
      CD8+ T lymphocytes specific for glutamic acid decarboxylase 90-98 epitope mediate diabetes in NODSCID mouse.
      ,
      • Quinn A.
      • McInerney M.F.
      • Sercarz E.E.
      MHC class I-restricted determinants on the glutamic acid decarboxylase 65 molecule induce spontaneous CTL activity.
      )
      Insulin-1 (Ins1)39–47LYLVCGERG102639KdYesIslets, PaLN, spleen(
      • Yu C.
      • Burns J.C.
      • Robinson W.H.
      • Utz P.J.
      • Ho P.P.
      • Steinman L.
      • Frey A.B.
      Identification of candidate tolerogenic CD8+ T cell epitopes for therapy of type 1 diabetes in the NOD mouse model.
      ,
      • Ejrnaes M.
      • Videbaek N.
      • Christen U.
      • Cooke A.
      • Michelsen B.K.
      • von Herrath M.
      Different diabetogenic potential of autoaggressive CD8+ clones associated with IFN-γ-inducible protein 10 (CXC chemokine ligand 10) production but not cytokine expression, cytolytic activity, or homing characteristics.
      ,
      • Wong F.S.
      • Karttunen J.
      • Dumont C.
      • Wen L.
      • Visintin I.
      • Pilip I.M.
      • Shastri N.
      • Pamer E.G.
      • Janeway Jr., C.A.
      Identification of an MHC class I-restricted autoantigen in type 1 diabetes by screening an organ-specific cDNA library.
      )
      101–107YQLENYC233116DbIslets(
      • Lamont D.
      • Mukherjee G.
      • Kumar P.R.
      • Samanta D.
      • McPhee C.G.
      • Kay T.W.
      • Almo S.C.
      • DiLorenzo T.P.
      • Serreze D.V.
      Compensatory mechanisms allow undersized anchor-deficient class I MHC ligands to mediate pathogenic autoreactive T cell responses.
      )
      Insulin-2 (Ins2)39–47LYLVCGERG102639KdYesIslets, PaLN, spleen(
      • Yu C.
      • Burns J.C.
      • Robinson W.H.
      • Utz P.J.
      • Ho P.P.
      • Steinman L.
      • Frey A.B.
      Identification of candidate tolerogenic CD8+ T cell epitopes for therapy of type 1 diabetes in the NOD mouse model.
      ,
      • Ejrnaes M.
      • Videbaek N.
      • Christen U.
      • Cooke A.
      • Michelsen B.K.
      • von Herrath M.
      Different diabetogenic potential of autoaggressive CD8+ clones associated with IFN-γ-inducible protein 10 (CXC chemokine ligand 10) production but not cytokine expression, cytolytic activity, or homing characteristics.
      ,
      • Wong F.S.
      • Karttunen J.
      • Dumont C.
      • Wen L.
      • Visintin I.
      • Pilip I.M.
      • Shastri N.
      • Pamer E.G.
      • Janeway Jr., C.A.
      Identification of an MHC class I-restricted autoantigen in type 1 diabetes by screening an organ-specific cDNA library.
      )
      49–58FYTPMSRREV102453KdYes(
      • Martinez N.R.
      • Augstein P.
      • Moustakas A.K.
      • Papadopoulos G.K.
      • Gregori S.
      • Adorini L.
      • Jackson D.C.
      • Harrison L.C.
      Disabling an integral CTL epitope allows suppression of autoimmune diabetes by intranasal proinsulin peptide.
      )
      103–109YQLENYC233116DbIslets(
      • Lamont D.
      • Mukherjee G.
      • Kumar P.R.
      • Samanta D.
      • McPhee C.G.
      • Kay T.W.
      • Almo S.C.
      • DiLorenzo T.P.
      • Serreze D.V.
      Compensatory mechanisms allow undersized anchor-deficient class I MHC ligands to mediate pathogenic autoreactive T cell responses.
      )
      Insulin gene enhancer protein ISL-1 (Isl1)65–74TYCKRDYIRL1312049KdIslets(
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
      • Verdier Y.
      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      )
      Islet cell autoantigen 1 (Ica1)78–86LYQKRICFL546770KdPaLN(
      • Yu C.
      • Burns J.C.
      • Robinson W.H.
      • Utz P.J.
      • Ho P.P.
      • Steinman L.
      • Frey A.B.
      Identification of candidate tolerogenic CD8+ T cell epitopes for therapy of type 1 diabetes in the NOD mouse model.
      )
      Myotonin-protein kinase (Dmpk)138–146FQDENYLYL104489DbIslets(
      • Lieberman S.M.
      • Takaki T.
      • Han B.
      • Santamaria P.
      • Serreze D.V.
      • DiLorenzo T.P.
      Individual nonobese diabetic mice exhibit unique patterns of CD8+ T cell reactivity to three islet antigens, including the newly identified widely expressed dystrophia myotonica kinase.
      )
      Neuroendocrine convertase 2 (Pcsk2)320–328GYASSMWTI1311036KdIslets(
      • Mukherjee G.
      • Chaparro R.J.
      • Schloss J.
      • Smith C.
      • Bando C.D.
      • DiLorenzo T.P.
      Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice.
      )
      341–350LYDESCSSTL1312021KdIslets(
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
      • Verdier Y.
      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      )
      501–510RYLEHVQAVI1312037KdIslets(
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
      • Verdier Y.
      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      )
      Neuroendocrine protein 7B2 (Scg5)26–35AYSPRTPDRV1311981KdIslets(
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
      • Verdier Y.
      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      )
      193–201DNVVAKKSV1311986KdIslets(
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
      • Verdier Y.
      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      )
      Paternally expressed gene 3 protein (Peg3)522–530CKVCGESFL1311015KdIslets(
      • Mukherjee G.
      • Chaparro R.J.
      • Schloss J.
      • Smith C.
      • Bando C.D.
      • DiLorenzo T.P.
      Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice.
      )
      Sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (Atp2a2)688–696EFLQSFDEI1311022KdIslets(
      • Mukherjee G.
      • Chaparro R.J.
      • Schloss J.
      • Smith C.
      • Bando C.D.
      • DiLorenzo T.P.
      Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice.
      )
      835–843RYLAIGCYV1311083KdIslets(
      • Mukherjee G.
      • Chaparro R.J.
      • Schloss J.
      • Smith C.
      • Bando C.D.
      • DiLorenzo T.P.
      Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice.
      )
      Secretogranin-2 (Scg2)469–477PYGPGKSRA1311070KdIslets(
      • Mukherjee G.
      • Chaparro R.J.
      • Schloss J.
      • Smith C.
      • Bando C.D.
      • DiLorenzo T.P.
      Glucagon-reactive islet-infiltrating CD8 T cells in NOD mice.
      )
      Urocortin-3 (Ucn3)5–13TYFLLPLLL1312050KdIslets(
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
      • Verdier Y.
      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      )
      32–40VFSCLNTAL1312051KdIslets(
      • Azoury M.E.
      • Tarayrah M.
      • Afonso G.
      • Pais A.
      • Colli M.L.
      • Maillard C.
      • Lavaud C.
      • Alexandre-Heymann L.
      • Gonzalez-Duque S.
      • Verdier Y.
      • Vinh J.
      • Pinto S.
      • Buus S.
      • Dubois-Laforgue D.
      • Larger E.
      • et al.
      Peptides derived from insulin granule proteins are targeted by CD8+ T cells across MHC class I restrictions in humans and NOD mice.
      )
      Zinc transporter 8 (Slc30a8)158–166LYLACERLL546769KdPaLN, spleen(
      • Yu C.
      • Burns J.C.
      • Robinson W.H.
      • Utz P.J.
      • Ho P.P.
      • Steinman L.
      • Frey A.B.
      Identification of candidate tolerogenic CD8+ T cell epitopes for therapy of type 1 diabetes in the NOD mouse model.
      )
      282–290SYNSVKEII546777KdPaLN, spleen(
      • Yu C.
      • Burns J.C.
      • Robinson W.H.
      • Utz P.J.
      • Ho P.P.
      • Steinman L.
      • Frey A.B.
      Identification of candidate tolerogenic CD8+ T cell epitopes for therapy of type 1 diabetes in the NOD mouse model.
      )
      Proteins in bold contribute both CD4+ and CD8+ T cell epitopes.
      Abbreviations: IEDB, Immune Epitope Database; PaLN, pancreatic lymph node.
      Figure thumbnail gr2
      Figure 2Demonstration of the utility of the NOD mouse model in the identification of human-relevant islet antigens. The islet sources of the conventional T cell epitopes in NOD mice ( and ) and humans (
      • James E.A.
      • Mallone R.
      • Kent S.C.
      • DiLorenzo T.P.
      T-cell epitopes and neo-epitopes in type 1 diabetes: A comprehensive update and reappraisal.
      ) are listed on the y-axis in alphabetical order according to their UniProt consortium names (www.uniprot.org) (
      The UniProt Consortium
      UniProt: A worldwide hub of protein knowledge.
      ). For NOD mice, “Insulin” includes both Insulin-1 and Insulin-2 epitopes. The percent of all CD4+ (left) or CD8+ (right) T cell epitopes that derive from a given protein in each species are plotted on the x-axis; “n” indicates the total number of epitopes included in each of the sets. This analysis reveals good concordance between mouse and human antigens for both CD4+ and CD8+ T cells, as most of the islet proteins that are sources of T cell epitopes in humans also contribute epitopes in NOD mice.

      Noncontiguous CD4+ T cell epitopes

      A recent and paradigm-shifting advance that originated from study of the NOD mouse is the discovery of hybrid insulin peptides, or HIPs, as noncontiguous epitopes for beta cell–reactive CD4+ T cells (
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ). HIPs were first identified as the targets of several long-studied pathogenic CD4+ T cell clones from NOD mice (
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ) and were subsequently shown to be recognized by islet-infiltrating CD4+ T cells from patients with T1D (
      • Babon J.A.
      • DeNicola M.E.
      • Blodgett D.M.
      • Crevecoeur I.
      • Buttrick T.S.
      • Maehr R.
      • Bottino R.
      • Naji A.
      • Kaddis J.
      • Elyaman W.
      • James E.A.
      • Haliyur R.
      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      ,
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ). In the HIPs that have been reported to date (Table 3), a peptide segment derived from insulin (often including a portion of the normally excised C-peptide) is fused to a second peptide segment almost exclusively derived either from a different insulin secretory granule protein or from a noncontiguous portion of insulin itself (Fig. 3C). Although noncontiguous CD4+ T cell epitopes had not previously been described in any disease, since 2004 there have been several reports of noncontiguous epitopes generated by the proteasome and recognized by tumor-reactive cytotoxic CD8+ T cells isolated from cancer patients (
      • Dalet A.
      • Robbins P.F.
      • Stroobant V.
      • Vigneron N.
      • Li Y.F.
      • El-Gamil M.
      • Hanada K.
      • Yang J.C.
      • Rosenberg S.A.
      • Van den Eynde B.J.
      An antigenic peptide produced by reverse splicing and double asparagine deamidation.
      ,
      • Ebstein F.
      • Textoris-Taube K.
      • Keller C.
      • Golnik R.
      • Vigneron N.
      • Van den Eynde B.J.
      • Schuler-Thurner B.
      • Schadendorf D.
      • Lorenz F.K.
      • Uckert W.
      • Urban S.
      • Lehmann A.
      • Albrecht-Koepke N.
      • Janek K.
      • Henklein P.
      • et al.
      Proteasomes generate spliced epitopes by two different mechanisms and as efficiently as non-spliced epitopes.
      ,
      • Hanada K.
      • Yewdell J.W.
      • Yang J.C.
      Immune recognition of a human renal cancer antigen through post-translational protein splicing.
      ,
      • Michaux A.
      • Larrieu P.
      • Stroobant V.
      • Fonteneau J.F.
      • Jotereau F.
      • Van den Eynde B.J.
      • Moreau-Aubry A.
      • Vigneron N.
      A spliced antigenic peptide comprising a single spliced amino acid is produced in the proteasome by reverse splicing of a longer peptide fragment followed by trimming.
      ,
      • Vigneron N.
      • Stroobant V.
      • Chapiro J.
      • Ooms A.
      • Degiovanni G.
      • Morel S.
      • van der Bruggen P.
      • Boon T.
      • Van den Eynde B.J.
      An antigenic peptide produced by peptide splicing in the proteasome.
      ). Such CD8+ T cell epitopes, formed by a process termed “peptide splicing,” are characterized by the covalent linkage of two peptides derived from the same protein (cis-spliced peptides) (Fig. 3, A and B) or different proteins (trans-spliced peptides) (Fig. 3C). In the case of cis-spliced peptides, an intervening protein sequence has been removed, and the two linked segments can either be in their natural order (i.e., as they appear in the protein) (Fig. 3A) or in reverse order (Fig. 3B). Although HIP epitopes for CD4+ T cells may seem at first glance to be analogous to trans-spliced tumor epitopes recognized by CD8+ T cells (Fig. 3C), to date there is no evidence that the proteasome participates in HIP formation. Thus, for clarity, here we reserve the term “spliced peptides” for noncontiguous CD8+ T cell epitopes or class I MHC ligands only and do not describe HIPs in this way. This nomenclature, summarized in Figure 3, is consistent with the majority of the literature on this subject.
      Table 3Noncontiguous CD4+ T cell epitopes for islet antigens in NOD mice and humans
      HostSegment 1Segment 2IEDB epitope identifierMHCT cell sourceReference
      Protein (gene)PositionSequenceProtein (gene)PositionSequence
      MouseInsulin-1 (Ins1)75–80LQTLALChromogranin-A (ChgA)358–362WSRMD910154Ag7Blood, islets,(
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ,
      • Baker R.L.
      • Jamison B.L.
      • Wiles T.A.
      • Lindsay R.S.
      • Barbour G.
      • Bradley B.
      • Delong T.
      • Friedman R.S.
      • Nakayama M.
      • Haskins K.
      CD4 T cells reactive to hybrid insulin peptides are indicators of disease activity in the NOD mouse.
      )
      Insulin-2 (Ins2)77–82LQTLALPaLN, spleen
      Insulin-1 (Ins1)75–80LQTLALIslet amyloid polypeptide78–83NAARDP910153Ag7Blood, islets,(
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ,
      • Baker R.L.
      • Jamison B.L.
      • Wiles T.A.
      • Lindsay R.S.
      • Barbour G.
      • Bradley B.
      • Delong T.
      • Friedman R.S.
      • Nakayama M.
      • Haskins K.
      CD4 T cells reactive to hybrid insulin peptides are indicators of disease activity in the NOD mouse.
      ,
      • Wiles T.A.
      • Delong T.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Powell R.L.
      • Reisdorph N.
      • Haskins K.
      An insulin-IAPP hybrid peptide is an endogenous antigen for CD4 T cells in the non-obese diabetic mouse.
      )
      Insulin-2 (Ins2)77–82LQTLAL(Iapp)PaLN, spleen
      HumanInsulin (INS)34–41HLVEALYLSecretogranin-1 (CHGB)211–218EELVARSE1084801DR0401Blood(
      • Arribas-Layton D.
      • Guyer P.
      • Delong T.
      • Dang M.
      • Chow I.T.
      • Speake C.
      • Greenbaum C.J.
      • Kwok W.W.
      • Baker R.L.
      • Haskins K.
      • James E.A.
      Hybrid insulin peptides are recognized by human T cells in the context of DRB1∗04:01.
      )
      Insulin (INS)42–49VCGERGFFSecretogranin-1 (CHGB)211–218EELVARSE1086861DR0401Blood(
      • Arribas-Layton D.
      • Guyer P.
      • Delong T.
      • Dang M.
      • Chow I.T.
      • Speake C.
      • Greenbaum C.J.
      • Kwok W.W.
      • Baker R.L.
      • Haskins K.
      • James E.A.
      Hybrid insulin peptides are recognized by human T cells in the context of DRB1∗04:01.
      )
      Insulin (INS)64–70GQVELGGChromogranin-A (CHGA)342–349WSKMDQLA1145014n.d.Blood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)64–70GQVELGGChromogranin-A (CHGA)358–365LEGQEEEE1145010n.d.Blood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)64–71GQVELGGGInsulin (INS)57–63EAEDLQV1310104n.d.Blood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)64–71GQVELGGGInsulin (INS)90–96GIVEQCC583306n.d.Blood, islets(
      • Babon J.A.
      • DeNicola M.E.
      • Blodgett D.M.
      • Crevecoeur I.
      • Buttrick T.S.
      • Maehr R.
      • Bottino R.
      • Naji A.
      • Kaddis J.
      • Elyaman W.
      • James E.A.
      • Haliyur R.
      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      ,
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)64–71GQVELGGGIslet amyloid polypeptide (IAPP)23–29TPIESHQ583307Class IIIslets(
      • Babon J.A.
      • DeNicola M.E.
      • Blodgett D.M.
      • Crevecoeur I.
      • Buttrick T.S.
      • Maehr R.
      • Bottino R.
      • Naji A.
      • Kaddis J.
      • Elyaman W.
      • James E.A.
      • Haliyur R.
      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      )
      Insulin (INS)64–71GQVELGGGIslet amyloid polypeptide (IAPP)74–80NAVEVLK505706DQ8Blood, islets(
      • Babon J.A.
      • DeNicola M.E.
      • Blodgett D.M.
      • Crevecoeur I.
      • Buttrick T.S.
      • Maehr R.
      • Bottino R.
      • Naji A.
      • Kaddis J.
      • Elyaman W.
      • James E.A.
      • Haliyur R.
      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      ,
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ,
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)64–71GQVELGGGPro-neuropeptide Y (NPY)68–74SSPETLI505707DQ8Blood, islets(
      • Babon J.A.
      • DeNicola M.E.
      • Blodgett D.M.
      • Crevecoeur I.
      • Buttrick T.S.
      • Maehr R.
      • Bottino R.
      • Naji A.
      • Kaddis J.
      • Elyaman W.
      • James E.A.
      • Haliyur R.
      • Brissova M.
      • Overbergh L.
      • Mathieu C.
      • et al.
      Analysis of self-antigen specificity of islet-infiltrating T cells from human donors with type 1 diabetes.
      ,
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.
      ,
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)64–71GQVELGGGSecretogranin-1 (CHGB)440–446FLGEGHH1310105n.d.Blood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)76–82SLQPLALChromogranin-A (CHGA)342–348WSKMDQL1169825n.d.Blood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)76–82SLQPLALInsulin (INS)57–63EAEDLQV1169818DQBlood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)76–82SLQPLALInsulin (INS)90–96GIVEQCC1169820DRBlood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)76–82SLQPLALIslet amyloid polypeptide (IAPP)23–29TPIESHQ1169824n.d.Blood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)76–82SLQPLALIslet amyloid polypeptide (IAPP)74–80NAVEVLK1169822DRBlood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)76–82SLQPLALSecretogranin-1 (CHGB)440–446FLGEGHH1169819n.d.Blood(
      • Baker R.L.
      • Rihanek M.
      • Hohenstein A.C.
      • Nakayama M.
      • Michels A.
      • Gottlieb P.A.
      • Haskins K.
      • Delong T.
      Hybrid insulin peptides are autoantigens in type 1 diabetes.
      )
      Insulin (INS)78–85QPLALEGSEndoplasmic reticulum chaperone BiP (HSPA5)298–305ALSSQHQA1085904DR0401Blood(
      • Arribas-Layton D.
      • Guyer P.
      • Delong T.
      • Dang M.
      • Chow I.T.
      • Speake C.
      • Greenbaum C.J.
      • Kwok W.W.
      • Baker R.L.
      • Haskins K.
      • James E.A.
      Hybrid insulin peptides are recognized by human T cells in the context of DRB1∗04:01.
      )
      Insulin (INS)85–92SLQKRGIVSecretogranin-1 (CHGB)211–218EELVARSE1086541DR0401Blood(
      • Arribas-Layton D.
      • Guyer P.
      • Delong T.
      • Dang M.
      • Chow I.T.
      • Speake C.
      • Greenbaum C.J.
      • Kwok W.W.
      • Baker R.L.
      • Haskins K.
      • James E.A.
      Hybrid insulin peptides are recognized by human T cells in the context of DRB1∗04:01.
      )
      Insulin (INS)99–106ICSLYQLEInsulin (INS)25–32FVNQHLCG1084880DR0401Blood(
      • Arribas-Layton D.
      • Guyer P.
      • Delong T.
      • Dang M.
      • Chow I.T.
      • Speake C.
      • Greenbaum C.J.
      • Kwok W.W.
      • Baker R.L.
      • Haskins K.
      • James E.A.
      Hybrid insulin peptides are recognized by human T cells in the context of DRB1∗04:01.
      )
      Insulin (INS)100–107CSLYQLENNeuroendocrine protein 7B2 (SCG5)200–207SVPHFSDE1083949DR0401Blood(
      • Arribas-Layton D.
      • Guyer P.
      • Delong T.
      • Dang M.
      • Chow I.T.
      • Speake C.
      • Greenbaum C.J.
      • Kwok W.W.
      • Baker R.L.
      • Haskins K.
      • James E.A.
      Hybrid insulin peptides are recognized by human T cells in the context of DRB1∗04:01.
      )
      n.d., not determined, but presumed class II.
      Abbreviations: IEDB, Immune Epitope Database; PaLN, pancreatic lymph node.
      Figure thumbnail gr3
      Figure 3Nomenclature for noncontiguous T cell epitopes. A and B, shown at the left are amino acid residues of a segment from hypothetical protein X, where each triangle represents one amino acid. Green and orange residues denote the peptide fragments that constitute the CD8+ T cell epitopes formed by peptide splicing and shown at the right. Blue residues denote the missing intervening sequence. The segments of cis-spliced peptides can either appear in their natural order (i.e., as they appear in the protein) (A) or in reverse order (B). C, depicted in purple and gray are hypothetical segments of two proteins, Y and Z. Peptides from two different protein molecules can form CD8+ T cell epitopes by trans-splicing, in which each protein contributes residues to the resulting peptide epitope (top right). In the text, the term “spliced peptide” is reserved for a CD8+ T cell epitope or a class I MHC ligand, whereas a CD4+ T cell epitope in which the purple and/or gray segments are derived from insulin (bottom right) is referred to as a hybrid insulin peptide.
      The line of investigation that ultimately led to the identification of HIPs was initially inspired by studies to identify the peptide recognized by the T cell clone BDC-2.5, one of a set of pathogenic CD4+ T cell clones isolated from the lymph nodes and spleens of diabetic NOD mice, with BDC denoting their origin at the Barbara Davis Center for Childhood Diabetes in Colorado (
      • Haskins K.
      Pathogenic T-cell clones in autoimmune diabetes: More lessons from the NOD mouse.
      ). When WE14, a natural cleavage product of chromogranin-A, was identified as the epitope recognized by BDC-2.5, it was a puzzling finding, as the peptide was predicted to leave empty the N-terminal portion of the H2-Ag7 peptide-binding groove (
      • Stadinski B.D.
      • Delong T.
      • Reisdorph N.
      • Reisdorph R.
      • Powell R.L.
      • Armstrong M.
      • Piganelli J.D.
      • Barbour G.
      • Bradley B.
      • Crawford F.
      • Marrack P.
      • Mahata S.K.
      • Kappler J.W.
      • Haskins K.
      Chromogranin A is an autoantigen in type 1 diabetes.
      ). Furthermore, mass spectrometry analysis of chromatographic fractions of beta cell extracts revealed that T cell stimulatory activity did not track with the abundance of WE14. Rather, active fractions contained insulin's C-peptide and fragments thereof. This led to the hypothesis, subsequently proven (
      • Delong T.
      • Wiles T.A.
      • Baker R.L.
      • Bradley B.
      • Barbour G.
      • Reisdorph R.
      • Armstrong M.
      • Powell R.L.
      • Reisdorph N.
      • Kumar N.
      • Elso C.M.
      • DeNicola M.
      • Bottino R.
      • Powers A.C.
      • Harlan D.M.
      • et al.
      Pathogenic CD4 T cells in type 1 diabetes recognize epitopes formed by peptide fusion.