scholarly journals B7-CD28 co-stimulation modulates central tolerance via thymic clonal deletion and Treg generation through distinct mechanisms

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Masashi Watanabe ◽  
Ying Lu ◽  
Michael Breen ◽  
Richard J. Hodes
Keyword(s):  
Treg Cell ◽  
Specific Antigen ◽  
Cell Generation ◽  
Thymic Epithelial Cells ◽  
T Cell Repertoire ◽  
Cellular Mechanisms ◽  
Cell Repertoire ◽  
Clonal Deletion ◽  
Central Tolerance ◽  
Antigen Presenting

AbstractThe molecular and cellular mechanisms mediating thymic central tolerance and prevention of autoimmunity are not fully understood. Here we show that B7-CD28 co-stimulation and B7 expression by specific antigen-presenting cell (APC) types are required for clonal deletion and for regulatory T (Treg) cell generation from endogenous tissue-restricted antigen (TRA)-specific thymocytes. While B7-CD28 interaction is required for both clonal deletion and Treg induction, these two processes differ in their CD28 signaling requirements and in their dependence on B7-expressing dendritic cells, B cells, and thymic epithelial cells. Meanwhile, defective thymic clonal deletion due to altered B7-CD28 signaling results in the accumulation of mature, peripheral TRA-specific T cells capable of mediating destructive autoimmunity. Our findings thus reveal a function of B7-CD28 co-stimulation in shaping the T cell repertoire and limiting autoimmunity through both thymic clonal deletion and Treg cell generation.

scholarly journals Epithelial and dendritic cells in the thymic medulla promote CD4+Foxp3+ regulatory T cell development via the CD27–CD70 pathway

2013 ◽  
Vol 210 (4) ◽  
pp. 715-728 ◽  
Author(s):  
Jonathan M. Coquet ◽  
Julie C. Ribot ◽  
Nikolina Bąbała ◽  
Sabine Middendorp ◽  
Gerda van der Horst ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
T Cell ◽  
Treg Cell ◽  
Treg Cells ◽  
Cell Development ◽  
Cell Generation ◽  
Thymic Epithelial Cells ◽  
Clonal Deletion ◽  
Cell Numbers ◽  
Thymic Medulla

CD4+Foxp3+ regulatory T cells (Treg cells) are largely autoreactive yet escape clonal deletion in the thymus. We demonstrate here that CD27–CD70 co-stimulation in the thymus rescues developing Treg cells from apoptosis and thereby promotes Treg cell generation. Genetic ablation of CD27 or its ligand CD70 reduced Treg cell numbers in the thymus and peripheral lymphoid organs, whereas it did not alter conventional CD4+Foxp3− T cell numbers. The CD27–CD70 pathway was not required for pre-Treg cell generation, Foxp3 induction, or mature Treg cell function. Rather, CD27 signaling enhanced positive selection of Treg cells within the thymus in a cell-intrinsic manner. CD27 signals promoted the survival of thymic Treg cells by inhibiting the mitochondrial apoptosis pathway. CD70 was expressed on Aire− and Aire+ medullary thymic epithelial cells (mTECs) and on dendritic cells (DCs) in the thymic medulla. CD70 on both mTECs and DCs contributed to Treg cell development as shown in BM chimera experiments with CD70-deficient mice. In vitro experiments indicated that CD70 on the CD8α+ subset of thymic DCs promoted Treg cell development. Our data suggest that mTECs and DCs form dedicated niches in the thymic medulla, in which CD27–CD70 co-stimulation rescues developing Treg cells from apoptosis, subsequent to Foxp3 induction by TCR and CD28 signals.

T cell repertoire and clonal deletion of Mtv superantigen-reactive T cells in mice lacking CD4 and CD8 molecules

1995 ◽  
Vol 25 (7) ◽  
pp. 2115-2118 ◽  
Author(s):  
Josef M. Penninger ◽  
Marco W. Schilham ◽  
Emma Timms ◽  
Valerie A. Wallace ◽  
Tak W. Mak
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Clonal Deletion

scholarly journals Age-Related Changes in Thymic Central Tolerance

2021 ◽  
Vol 12 ◽  
Author(s):  
Jayashree Srinivasan ◽  
Jessica N. Lancaster ◽  
Nandini Singarapu ◽  
Laura P. Hale ◽  
Lauren I. R. Ehrlich ◽  
...  
Keyword(s):  
T Cells ◽  
Negative Selection ◽  
Thymic Epithelial Cells ◽  
Central Tolerance ◽  
Adult Transition ◽  
Treg Function ◽  
Age Related ◽  
And Function ◽  
Antigen Presenting ◽  
Age Related Changes

Thymic epithelial cells (TECs) and hematopoietic antigen presenting cells (HAPCs) in the thymus microenvironment provide essential signals to self-reactive thymocytes that induce either negative selection or generation of regulatory T cells (Treg), both of which are required to establish and maintain central tolerance throughout life. HAPCs and TECs are comprised of multiple subsets that play distinct and overlapping roles in central tolerance. Changes that occur in the composition and function of TEC and HAPC subsets across the lifespan have potential consequences for central tolerance. In keeping with this possibility, there are age-associated changes in the cellular composition and function of T cells and Treg. This review summarizes changes in T cell and Treg function during the perinatal to adult transition and in the course of normal aging, and relates these changes to age-associated alterations in thymic HAPC and TEC subsets.

scholarly journals The Aire family expands

2019 ◽  
Vol 216 (5) ◽  
pp. 1010-1011
Author(s):  
Adrian Liston ◽  
James Dooley
Keyword(s):  
T Cell ◽  
Epithelial Cells ◽  
Lymph Nodes ◽  
Thymic Epithelial Cells ◽  
T Cell Tolerance ◽  
T Cell Repertoire ◽  
Cell Tolerance ◽  
Cell Repertoire

T cell tolerance depends upon Aire-expressing cells to purge the T cell repertoire of autoreactive clones. Once thought to be the exclusive domain of thymic epithelial cells, a new study by Yamano et al. (https://doi.org/10.1084/jem.20181430) in this issue of JEM identifies ILC3-like cells in the lymph nodes with similar properties.

scholarly journals Atypical TRAV1-2− T cell receptor recognition of the antigen-presenting molecule MR1

2020 ◽  
Vol 295 (42) ◽  
pp. 14445-14457 ◽  
Author(s):  
Wael Awad ◽  
Erin W. Meermeier ◽  
Maria L. Sandoval-Romero ◽  
Jérôme Le Nours ◽  
Aneta H. Worley ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Mait Cells ◽  
Receptor Recognition ◽  
Antigen Presenting ◽  
Β Chain ◽  
Complementarity Determining Region

MR1 presents vitamin B–related metabolites to mucosal associated invariant T (MAIT) cells, which are characterized, in part, by the TRAV1-2+ αβ T cell receptor (TCR). In addition, a more diverse TRAV1-2− MR1-restricted T cell repertoire exists that can possess altered specificity for MR1 antigens. However, the molecular basis of how such TRAV1-2− TCRs interact with MR1–antigen complexes remains unclear. Here, we describe how a TRAV12-2+ TCR (termed D462-E4) recognizes an MR1–antigen complex. We report the crystal structures of the unliganded D462-E4 TCR and its complex with MR1 presenting the riboflavin-based antigen 5-OP-RU. Here, the TRBV29-1 β-chain of the D462-E4 TCR binds over the F′-pocket of MR1, whereby the complementarity-determining region (CDR) 3β loop surrounded and projected into the F′-pocket. Nevertheless, the CDR3β loop anchored proximal to the MR1 A′-pocket and mediated direct contact with the 5-OP-RU antigen. The D462-E4 TCR footprint on MR1 contrasted that of the TRAV1-2+ and TRAV36+ TCRs' docking topologies on MR1. Accordingly, diverse MR1-restricted T cell repertoire reveals differential docking modalities on MR1, thus providing greater scope for differing antigen specificities.

Shaping of the autoreactive T-cell repertoire by a splice variant of self protein expressed in thymic epithelial cells

10.1038/71540 ◽  
2000 ◽  
Vol 6 (1) ◽  
pp. 56-61 ◽  
Author(s):  
Ludger Klein ◽  
Matthias Klugmann ◽  
Klaus-Armin Nave ◽  
V K Tuohy ◽  
Bruno Kyewski
Keyword(s):  
T Cell ◽  
Epithelial Cells ◽  
Splice Variant ◽  
Thymic Epithelial Cells ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Autoreactive T Cell

scholarly journals In vitro correlate for a clonal deletion mechanism of immune response gene-controlled nonresponsiveness.

1983 ◽  
Vol 157 (3) ◽  
pp. 998-1005 ◽  
Author(s):  
N Ishii ◽  
Z A Nagy ◽  
J Klein
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Response Gene ◽  
Mouse Strains ◽  
Single Chain ◽  
Cell Repertoire ◽  
Clonal Deletion ◽  
Class Ii Mhc ◽  
Antigen Presenting

We used T cell-antigen-presenting cell (APC) combinations from two pairs of recombinant mouse strains, B10.A(4R)-B10.A(2R) and B10.S(7R)-B10.S(9R) (abbreviated 4R, 2R, 7R, 9R, respectively), which differ from each other only in the nonexpression vs. expression of cell-surface E molecules, to study the mechanism of the Ir gene-controlled (E-restricted) response to the terpolymer poly(glu51lys34tyr15) (GLT). No response to GLT occurred when the APC were from E-nonexpressor strains 4R and 7R. When APC from E-expressor strains were used and alloreactivity against the incompatible E molecules was removed by BUdR + light treatment, 7R T cells responded to GLT presented by 9R APC, but 4R T cells failed to respond to GLT presented by 2R APC. However, 4R T cells mounted a proliferative response to GLT presented by fully allogeneic 5R or 9R APC. The latter response was completely abolished by the depletion of cells alloreactive against 2R and 5R or 2R and 9R. Since removal of alloreactivity against 5R plus 9R did not affect the response of 4R T cells to GLT presented by either 5R or 9R cells, we conclude that the 4R T cells generated in response to GLT cross-react with the additional incompatibility presented by 2R cells, that is, the Ek beta chain. In contrast, 7R T cells recognizing GLT presented by 9R APC do not cross-react with Ek beta. These results demonstrate that "blind spots" in the T cell repertoire produced by depletion of cells alloreactive against a single chain of a class II MHC molecule can render a strain nonresponsive to a synthetic polypeptide antigen, and that this nonresponsiveness corresponds to that attributed to the MHC-linked Ir genes.

scholarly journals Macroautophagy substrates are loaded onto MHC class II of medullary thymic epithelial cells for central tolerance

2013 ◽  
Vol 210 (2) ◽  
pp. 287-300 ◽  
Author(s):  
Martin Aichinger ◽  
Chunyan Wu ◽  
Jelena Nedjic ◽  
Ludger Klein
Keyword(s):  
Epithelial Cells ◽  
Mhc Class Ii ◽  
Negative Selection ◽  
Class Ii ◽  
Single Amino Acid ◽  
Thymic Epithelial Cells ◽  
Clonal Deletion ◽  
Central Tolerance ◽  
Metabolic Functions ◽  
Physiological Relevance

Macroautophagy serves cellular housekeeping and metabolic functions through delivery of cytoplasmic constituents for lysosomal degradation. In addition, it may mediate the unconventional presentation of intracellular antigens to CD4+ T cells; however, the physiological relevance of this endogenous MHC class II loading pathway remains poorly defined. Here, we characterize the role of macroautophagy in thymic epithelial cells (TECs) for negative selection. Direct presentation for clonal deletion of MHC class II–restricted thymocytes required macroautophagy for a mitochondrial version of a neo-antigen, but was autophagy-independent for a membrane-bound form. A model antigen specifically expressed in Aire+ medullary TECs (mTECs) induced efficient deletion via direct presentation when targeted to autophagosomes, whereas interference with autophagosomal routing of this antigen through exchange of a single amino acid or ablation of an essential autophagy gene abolished direct presentation for negative selection. Furthermore, when this autophagy substrate was expressed by mTECs in high amounts, endogenous presentation and indirect presentation by DCs operated in a redundant manner, whereas macroautophagy-dependent endogenous loading was essential for clonal deletion at limiting antigen doses. Our findings suggest that macroautophagy supports central CD4+ T cell tolerance through facilitating the direct presentation of endogenous self-antigens by mTECs.

scholarly journals Thymic Medullary Epithelial Cell Differentiation, Thymocyte Emigration, and the Control of Autoimmunity Require Lympho–Epithelial Cross Talk via LTβR

2003 ◽  
Vol 198 (5) ◽  
pp. 757-769 ◽  
Author(s):  
Thomas Boehm ◽  
Stefanie Scheu ◽  
Klaus Pfeffer ◽  
Conrad C. Bleul
Keyword(s):  
Epithelial Cells ◽  
Cross Talk ◽  
Three Dimensional ◽  
Tolerance Induction ◽  
Nuclear Factor Κb ◽  
Thymic Epithelial Cells ◽  
Cell Repertoire ◽  
Central Tolerance ◽  
Signaling Axis ◽  
Normal Differentiation

Thymocytes depend on the interaction with thymic epithelial cells for the generation of a diverse, nonautoreactive T cell repertoire. In turn, thymic epithelial cells acquire their three-dimensional cellular organization via instructive signals from developing thymocytes. The nature of these signals has been elusive so far. We show that thymocytes and medullary epithelial cells (MECs) communicate via the lymphotoxin β receptor (LTβR) signaling axis. Normal differentiation of thymic MECs requires LTβR ligand on thymocytes and LTβR together with nuclear factor–κB-inducing kinase (Nik) in thymic epithelial cells. Impaired lympho–epithelial cross talk in the absence of the LTβR causes aberrant differentiation and reduced numbers of thymic MECs, leads to the retention of mature T lymphocytes, and is associated with autoimmune phenomena, suggesting an unexpected role for LTβR signaling in central tolerance induction.

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