Central tolerance spares the private high‐avidity CD4⁺ T‐cell repertoire specific for an islet antigen in NOD mice

Abstract

Although central tolerance induces the deletion of most autoreactive T cells, some autoreactive T cells escape thymic censorship. Whether potentially harmful autoreactive T cells present distinct TCRαβ features remains unclear.Here, we analyzed the TCRαβ repertoire of CD4 + T cells specific for the S100β protein, an islet antigen associated with type 1 diabetes. We found that diabetes-resistant NOD mice deficient for thymus specific serine protease (TSSP), a protease that impairs class II antigen presentation by thymic stromal cells, were hyporesponsive to the immunodominant S100β 1-15 epitope, as compared to wild-type NOD mice, due to intrathymic negative selection. In both TSSP-deficient and wild-type NOD mice, the TCRαβ repertoire of S100β-specific CD4 + T cells though diverse showed a specific bias for dominant TCRα rearrangements with limited CDR3α diversity. These dominant TCRα chains were public since they were found in all mice. They were of intermediate-to low-avidity. In contrast, high-avidity T cells expressed unique TCRs specific to each individual (private TCRs) and were only found in wild-type NOD mice. Hence, in NOD mice, the autoreactive CD4 + T-cell compartment has two major components, a dominant and public low-avidity TCRα repertoire and a private high-avidity CD4 + T-cell repertoire; the latter is deleted by re-enforced negative selection.Keywords: Autoimmunity r Avidity r CD4 + T cells r NOD r TCR repertoire r T-cell tolerance Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionClonal deletion in the thymus is a major mechanism establishing T-cell tolerance to self-antigens (Ag). The seminal demonstration of ectopic expression of peripheral tissue Ags (TSA) by thymic APCs provided the mechanistic basis for the deletion of T cells specific for a large number of TSA [1,2]. Central tolerance is incomplete, however, and it has been estimated that thymic deleCorrespondence: Dr. Sylvie Guerder e-mail: Sylvie.guerder@inserm.fr tion may spare up to 25-40% of positively selected T cells [3]. It is well established that most of these self-reactive T cells show relatively low avidity for their cognate ligand, yet little is known regarding the specific features of their TCRαβ repertoire notably for polyclonal T cells specific for TSA.To further characterize how negative selection shapes the TCR repertoire of T cells reacting to TSA we analyzed the specific features of CD4 + T cells specific for an islet-Ag in conventional NOD mice and NOD mice with reinforced central deletion. The peripheral T-cell repertoire of NOD mice is highly autoreactive and includes CD4 + T cells specific for a large number of islet Ags [4]. This accumulation of islet-reactive CD4 + T cells results, at C 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu Eur. J. Immunol. 2015. 45: 1946-1956 Cellular immune response 1947 least in part, from defects in central tolerance mainly linked to defects in apoptosis induction [5][6][7][8]. Defects in c...

Apportioning Blame: Autoreactive CD4+ and CD8+ T Cells in Type 1 Diabetes

“…Furthermore, there is a sustained response against S100beta during the course of the disease and several years after diagnosis. In the NOD mice, S100beta peptide epitopes recognized by CD4 + T lymphocytes have been described and, although presented by a completely different MHC molecule (the I-A g7 molecule, homologous to the HLA-DQ8 in humans), the dominant peptide epitopes are similar to those presented by HLA-DR4 in human T1D as we previously reported (Serre et al 2015).…”

“…However, the role played by autoantibodies in the development of insulin resistance and diabetes is still controversial and more studies are needed to resolve this. Both S100beta and GFAP also induce T cell responses both in the NOD mice and human T1D patients (Banwell et al 2008;Gomez-Tourino et al 2015;Serre et al 2015;Standifer et al 2006;Tsui et al 2008;Winer et al 2003): for S100beta, several peptide epitopes presented by HLA DR4 molecule were identified and T cell Han et al 2013) PPI pre-proinsulin, GAD 65 glutamic acid decarboxylase 65, IA-2 insulinoma antigen-2, ZnT8 zinc transporter 8, IGRP islet-specific glucose-6-phosphatase catalytic subunit related protein, GFAP glial fibrillary acidic protein, S100β neurotropic factor S100β a Antibodies: autoantibody detection in animal models and/or T1D patients; T cells: detection of either CD4 and/or CD8 T cell responses; Disease transfer: diabetes development after transfer of T cell lines/clones (either CD4 or CD8) into diabetes-free animals or diabetogenic autoantigen-specific TCR transgenic mice; Immunotherapy: disease treatment/clinical trials using whole antigen, peptides or antigen-encoding DNA vaccines b Only in irradiated NOD mice …”

The T Cell Repertoire–Diversifying Enzyme TSSP Contributes to Thymic Selection of Diabetogenic CD4 T Cell Specificities Reactive to ChgA and IAPP Autoantigens

“…In contrast, in thymic DCs, TSSP likely impairs the presentation of some selfligands, thus preventing central tolerance. Hence, TSSP-deficient BM-derived cells, most certainly thymic DCs, caused a marked deletion in immature BDC-10.1 thymocytes (this study), as well as NY4.1-Tg thymocytes and IA2b-and S100b-specific thymocytes (12,41). These observations suggest that, although expressed at a lower level in thymic DCs than in cTECs, TSSP substantially affects the assembly/presentation of MHC class II:peptide complexes by thymic DCs.…”

“…Indeed, we found that the development of thymocytes expressing the MHC class II-restricted BDC-10.1 and BDC-6.9 TCRs that react to ChgA and IAPP autoantigens, respectively, was impaired when the thymic stromal cells lacked TSSP. Combined with our previous demonstration that TSSP expression was necessary for the development of thymocytes expressing the NY4.1 diabetogenic TCR or for thymocytes specific for the IA2b or S100b Ags (12,41), these novel findings clearly show that TSSP has a substantial impact on the generation of the islet-reactive CD4 T cell repertoire.…”

Naturally presented HLA class l–restricted epitopes from the neurotrophic factor S100‐β are targets of the autoimmune response in type 1 diabetes

“…1C). Comparison of proteasome-generated peptides with A2.1-eluted peptide MS data (Table 1) indicates that the carboxy-terminal end of peptides S100 [10][11][12][13][14][15][16][17][18] (ALIDVFHQY) and S100 [20][21][22][23][24][25][26][27][28] ΔDa, difference between experimental and theoretical m/z (in Da); Experimental m/z, unique m/z present only in the peptide mix derived from K562/A2.1-S100-b cells; Position, amino acid position in the S100-b protein of the predicted peptide; Sequence, amino acid sequence of the predicted peptide; Theoretical m/z, m/z predicted by Findpept.…”