Maintenance of immune tolerance by Foxp3+ regulatory T cells requires CD69 expression

Although FoxP3+ regulatory T cells are key players in the maintenance of immune tolerance and autoimmunity, the lack of specific markers constitute an obstacle to their use for immunotherapy protocols. In this study, we have investigated the role of the C-type lectin receptor CD69 in the suppressor function of Tregs and maintenance of immune tolerance towards harmless inhaled antigens. We identified a novel FoxP3+CD69+ Treg subset capable to maintain immune tolerance and protect to developing inflammation. Although CD69+ and CD69-FoxP3+ Tregs exist in homeostasis, only CD69-expressing Tregs express high levels of CTLA-4, ICOS, CD38 and GITR suppression-associated markers, secrete high amounts of TGFβand have potent suppressor activity. This activity is regulated by STAT5 and ERK signaling pathways and is impaired by antibody-mediated down-regulation of CD69 expression. Moreover, immunotherapy with FoxP3+CD69+ Tregs restores the homeostasis in Cd69-/- mice, that fail to induce tolerance, and is also highly proficient in the prevention of inflammation. The identification of the FoxP3+CD69+ Treg subset paves the way toward the development of new therapeutic strategies to control immune homeostasis and autoimmunity.This work was supported by funding from the Spanish Ministry of Economy and Competitiveness: SAF2011-27330 to P.M., SAF2010-15106 to M.L.T and SAF2011-25834 to F.S-M.; grant INDISNET (S2010/BMD-2332) from Comunidad de Madrid and RETICS Enfermedades Cardiovasculares (RD12/0042/0056) from Instituto de Salud Carlos III to P.M and F. S-M; and ERC-2011-AdG294340-GENTRIS to F.S-M. J.R.C. was supported by a CNIC post-doctoral fellowship, R. S-D is funded with a pre-doctoral fellowship from Comunidad de Madrid and E.R.B. and A.M-M. were supported by a FPI pre-doctoral fellowship from the Spanish Ministry of Economy and Competitiveness. The CNIC is supported by the Spanish Ministry of Economy and Competitiveness and the Pro CNIC Foundation.Peer Reviewe

Maintenance of immune tolerance by Foxp3+ regulatory T cells requires CD69 expression

Although FoxP3+ regulatory T cells are key players in the maintenance of immune tolerance and autoimmunity, the lack of specific markers constitute an obstacle to their use for immunotherapy protocols. In this study, we have investigated the role of the C-type lectin receptor CD69 in the suppressor function of Tregs and maintenance of immune tolerance towards harmless inhaled antigens. We identified a novel FoxP3+CD69+ Treg subset capable to maintain immune tolerance and protect to developing inflammation. Although CD69+ and CD69−FoxP3+ Tregs exist in homeostasis, only CD69-expressing Tregs express high levels of CTLA-4, ICOS, CD38 and GITR suppression-associated markers, secrete high amounts of TGFβ and have potent suppressor activity. This activity is regulated by STAT5 and ERK signaling pathways and is impaired by antibody-mediated down-regulation of CD69 expression. Moreover, immunotherapy with FoxP3+CD69+ Tregs restores the homeostasis in Cd69−/− mice, that fail to induce tolerance, and is also highly proficient in the prevention of inflammation. The identification of the FoxP3+CD69+ Treg subset paves the way toward the development of new therapeutic strategies to control immune homeostasis and autoimmunityThis work was supported by funding from the Spanish Ministry of Economy and Competitiveness: SAF2011-27330 to P.M., SAF2010-15106 to M.L.T and SAF2011-25834 to F.S-M.; grant INDISNET (S2010/BMD-2332) from Comunidad de Madrid and RETICS Enfermedades Cardiovasculares (RD12/0042/0056) from Instituto de Salud Carlos III to P.M and F. S-M; and ERC-2011-AdG294340-GENTRIS to F.S-M. J.R.C. was supported by a CNIC post-doctoral fellowship, R. S-D is funded with a pre-doctoral fellowship from Comunidad de Madrid and E.R.B. and A.M-M. were supported by a FPI pre-doctoral fellowship from the Spanish Ministry of Economy and Competitiveness. The CNIC is supported by the Spanish Ministry of Economy and Competitiveness and the Pro CNIC Foundatio

A set point in the selection of the αβTCR T cell repertoire imposed by pre-TCR signaling strength

Signaling via the T cell receptor (TCR) is critical during the development, maintenance, and activation of T cells. Quantitative aspects of TCR signaling have an important role during positive and negative selection, lineage choice, and ability to respond to small amounts of antigen. By using a mutant mouse line expressing a hypomorphic allele of the CD3ζ chain, we show here that the strength of pre-TCR–mediated signaling during T cell development determines the diversity of the TCRβ repertoire available for positive and negative selection, and hence of the final αβTCR repertoire. This finding uncovers an unexpected, pre-TCR signaling–dependent and repertoire–shaping role for β-selection beyond selection of in-frame rearranged TCRβ chains. Our data furthermore support a model of pre-TCR signaling in which the arrangement of this receptor in stable nanoclusters determines its quantitative signaling capacity.This work was supported by Spanish Ministry of Economy and Competitiveness (MINECO) Grants SAF2013-47975-R and SAF2016-76394-R and Grant PID2019-104703GB-I00/AEI/10.13039/501100011033 from the Spanish Ministry of Science and Innovation (MICINN) (to H.M.v.S.) and FIS2016-78883-C2-2-P (to M.C.). W.W.S. was supported by the German Research Foundation (DFG) through BIOSS-EXC294 and CIBSS-EXC2189, SFB854 (B19), FOR2799 (SCHA976/8-1), and SFB1381 (A9). The Centre for Genomic Regulation acknowledges support of the Spanish Ministry of Economy and Competitiveness, “Centro de Excelencia Severo Ochoa,” and the Centres de Recerca de Catalunya Program/Generalitat de Catalunya. The Centro Biología Molecular Severo Ochoa has been supported by the Fundación Ramón Areces

RRAS2 shapes the TCR repertoire by setting the threshold for negative selection

Signal strength controls the outcome of αβ T cell selection in the thymus, resulting in death if the affinity of the rearranged TCR is below the threshold for positive selection, or if the affinity of the TCR is above the threshold for negative selection. Here we show that deletion of the GTPase RRAS2 results in exacerbated negative selection and above-normal expression of positive selection markers. Furthermore, Rras2-/- mice are resistant to autoimmunity both in a model of inflammatory bowel disease (IBD) and in a model of myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE). We show that MOG-specific T cells in Rras2-/- mice have reduced affinity for MOG/I-Ab tetramers, suggesting that enhanced negative selection leads to selection of TCRs with lower affinity for the self-MOG peptide. An analysis of the TCR repertoire shows alterations that mostly affect the TCRα variable (TRAV) locus with specific VJ combinations and CDR3α sequences that are absent in Rras2-/- mice, suggesting their involvement in autoimmunity.This work was funded by grants from Comisión Interministerial de Ciencia y Tecnología (SAF2016-76394-R to B. Alarcon), the “Comunidad de Madrid” (S2017/BMD-3671 to M. Fresno and B. Alarcon), and the European Research Council (ERC 2013-Advanced Grant 334763 “NOVARIPP” to B. Alarcon). The Centre for Genomic Regulation acknowledges support of the Spanish Ministry of Economy and Competitiveness, “Centro de Excelencia Severo Ochoa,” the Centres de Recerca de Catalunya Program/Generalitat de Catalunya, and the Centro de Biología Molecular Severo Ochoa to the Fundación Ramón Arece

Antigen presentation between T cells drives Th17 polarization under conditions of limiting antigen

T cells form immunological synapses with professional antigen-presenting cells (APCs) resulting in T cell activation and the acquisition of peptide antigen-MHC (pMHC) complexes from the plasma membrane of the APC. They thus become APCs themselves. We investigate the functional outcome of T-T cell antigen presentation by CD4 T cells and find that the antigen-presenting T cells (Tpres) predominantly differentiate into regulatory T cells (Treg), whereas T cells that have been stimulated by Tpres cells predominantly differentiate into Th17 pro-inflammatory cells. Using mice deficient in pMHC uptake by T cells, we show that T-T antigen presentation is important for the development of experimental autoimmune encephalitis and Th17 cell differentiation in vivo. By varying the professional APC:T cell ratio, we can modulate Treg versus Th17 differentiation in vitro and in vivo, suggesting that T-T antigen presentation underlies proinflammatory responses in conditions of antigen scarcity.This work was funded by grant no. SAF2016-76394-R, from the CICYT, by grant no. S2017/BMD-3671 from the Comunidad de Madrid, and by the European Research Council ERC 2013-Advanced Grant 334763 “NOVARIPP” (to B.A.). V.L.B. was supported by an ITN-Marie Curie Fellowship. CBMSO acknowledges the support of the Fundación Ramón Areces