Recent thymic emigrants are the preferential precursors of regulatory T cells differentiated in the periphery

© 2013 National Academy of Sciences.Most Forkhead box P3(+) (Foxp3(+)) CD4 regulatory T cell (Treg) precursors are newly formed thymocytes that acquire Foxp3 expression on antigen encounter in the thymus. Differentiation of Treg, however, can also occur in the periphery. What limits this second layer of self- and nonself-reactive Treg production in physiological conditions remains to be understood. In this work, we tested the hypothesis that, similarly to thymic Treg, the precursors of peripheral Treg are immature T cells. We show that CD4(+)CD8(-)Foxp3(-) thymocytes and recent thymic emigrants (RTEs), contrarily to peripheral naïve mature cells, efficiently differentiate into Treg on transfer into lymphopenic mice. By varying donor and recipient mice and conducting ex vivo assays, we document that the preferential conversion of newly formed T cells does not require intrathymic preactivation, is cell-intrinsic, and correlates with low and high sensitivity to natural inhibitors and inducers of Foxp3 expression, such as IL-6, T-cell receptor triggering, and TGF-β. Finally, ex vivo analysis of human thymocytes and peripheral blood T cells revealed that human RTE and newly developed T cells share an increased potential to acquire a FOXP3(bright)CD25(high) Treg phenotype. Our findings indicating that RTEs are the precursors of Tregs differentiated in the periphery should guide the design of Treg-based therapies.This work was funded by the Portuguese Research Council (FCT)under Grant PTDC/SAU-IMU/113541/2009 (to I.C.), fellowships (to R.S.P., A.C.L., and M.-L.B.), and a contract (to I.C.) and the European Union’s 7th Framework Programme (FP7/2007-2013) under Grant 241447 [Natural Immunomodulators as Novel Immunotherapies for Type 1 Diabetes (NAIMIT); to J.D.]

Inhibition of murine γδ lymphocyte expansion and effector function by regulatory αβ T cells is cell-contact-dependent and sensitive to GITR modulation

© 2010 WILEYγδ T cells are highly cytolytic lymphocytes that produce large amounts of pro-inflammatory cytokines during immune responses to multiple pathogens. Furthermore, their ability to kill tumor cells has fueled the development of γδ-T-cell-based cancer therapies. Thus, the regulation of γδ-T-cell activity is of great biological and clinical relevance. Here, we show that murine CD4+CD25+ αβ T cells, the vast majority of which express the Treg marker, Foxp3, abolish key effector functions of γδ T cells, namely the production of the pro-inflammatory cytokines, IFN-γ and IL-17, cytotoxicity, and lymphocyte proliferation in vitro and in vivo. We further show that suppression is dependent on cellular contact between Treg and γδ T cells, results in the induction of an anergic state in γδ lymphocytes, and can be partially reversed by manipulating glucocorticoid-induced TNF receptor-related protein (GITR) signals. Our data collectively dissect a novel mechanism by which the expansion and pro-inflammatory functions of γδ T cells are regulated.This work was supported by grant PTDC/SAU-MII/71662/2006 from Fundação para a Ciência e a Tecnologia (FCT), who also provided individual fellowships to J.C.R., A.dB., D.V.C. and I.C., and by an Installation Grant from the European Molecular Biology Organization (YIP Project 1440)

Foxp3 induction in human and murine thymus precedes the CD4+ CD8+ stage but requires early T-cell receptor expression

© 2010 Australasian Society for Immunology Inc. All rights reservedThe thymus generates a T-cell lineage dedicated to immune regulation, 'naturally occurring' regulatory T cells, best specified by the forkhead family transcription factor Foxp3. Here, we have conducted a parallel study in humans and mice where we have dissected the earliest stages of Foxp3 induction during thymocyte development. By analyzing a large collection of 21 human thymuses we show that Foxp3 can be consistently detected in CD4 immature single positive thymocytes that precede the CD4(+)CD8(+) (double positive, DP) stage. The reduced levels of CD3 expression found at this stage of human thymocyte development raise the question of TCR (T-cell receptor) requirement for Foxp3 induction. We further show that, in mice, Foxp3 expression was also detected in pre-DP thymocytes of TCRalpha-sufficient but not in TCRalpha-deficient animals, genetically showing the TCR dependence of Foxp3 expression at pre-DP stages of T-cell development.This work was supported by grant (PTDC/SAU-MI/66248/2006) from ‘Fundação para a Ciência e a Tecnologia’ (FCT) and by ‘Programa Operacional Ciência e Inovação 2010’ (POCI2010) to AES and by a European Molecular Biology Organization Installation Grant to BSS. HNC received a scholarship from FCT co-financed by POCI 2010, and JCR received a post-doctoral fellowship from FCT

Delta-like 1–mediated notch signaling enhances the in vitro conversion of human memory CD4 T cells into FOXP3-expressing regulatory T cells

© 2014 by The American Association of Immunologists, Inc.FOXP3-expressing regulatory T cells (Treg) are essential for the prevention of autoimmunity and were shown to be reduced and/or dysfunctional in several autoimmune diseases. Although Treg-based adoptive transfer represents a promising therapy, the large cell number required to achieve clinical efficacy constitutes an important limitation. Therefore, novel strategies to generate bona fide in vitro-induced Treg (iTreg) are critical. In this study, we report that human memory CD4 T cells can be efficiently converted into iTreg, and that Delta-like 1 (DL1)-mediated Notch signaling significantly enhances this process. The iTreg generated in the presence of DL1 featured higher levels of Treg function-associated molecules and were efficient suppressors. Importantly, these iTreg displayed a stable phenotype in long-term cultures, even in the presence of proinflammatory cytokines. Additionally, DL1 potentiated FOXP3 acquisition by memory CD4 cells through the modulation of the TGF-β signaling pathway and of Foxp3 transcription. Our data demonstrate that iTreg can be efficiently induced from memory CD4 cells, a subset enriched in relevant specificities for targeting in autoimmune diseases, and that DL1 enhances this process. DL1 also enhanced the proliferation and Treg function-associated marker expression of ex vivo-stimulated human circulating FOXP3(+) cells. Manipulation of the Notch signaling pathway constitutes a promising approach to boost the in vitro generation of iTreg and ex vivo Treg expansion, thus facilitating the establishment of effective Treg-based adoptive therapy in autoimmune diseases.This work was supported by Fundação para a Ciência e Tecnologia, Portugal Grant PTDC/SAU-IMU/113541/2009 (to I.C.) and Fellowship SFRH/SINTD/60059/2009 (to C.M.)