Project description:The aim is to determine which genes are distinctively expressed in each of the subsets of DCs Four subsets of dendritic cells in mouse thymus were sorted based on their expression of Sirpa and their maturation status: Sirpa+ immature DCs, Sirpa+ mature DCs, Sirpa- immature DCs, and Sirpa- mature DCs
Project description:Dendritic cells (DC) play critical roles in central and peripheral T cell tolerance. DC found in the steady-state periphery undergo an homeostatic, tolerogenic, maturation that promotes interaction with naive T cells and induction of abortive responses. In contrast, thymic DC are thought to exist solely in an immature state. In this study, we show that XCR1+ thymic DC constitutively mature into a stage characterized by high levels of molecules involved in T cell activation. This unanticipated mature stage corresponded to a third of the XCR1+ thymic DC and fully accounted for their ability to cross-present self-antigens to developing T cells. Transcriptomic analysis of the XCR1+ DC found in thymus and steady-state periphery revealed that their maturation involves profound and convergent changes. Unexpectedly, maturation resulted in down-regulation of genes conferring their specific function on XCR1+ DC. Paradoxically, upon maturation, central and peripheral tolerogenic XCR1+ DC up-regulated many genes thought to drive pro-inflammatory T-cell responses. Thus, our results reveal that thymic XCR1+ DC undergo constitutive maturation and emphasize the common mechanisms operating for both central and peripheral tolerance induction by XCR1+ DC. DC were isolated from lymphoid organs as previously described (Vremec et al., 2000). DC subsets were sorted by flow cytometry according to the marker combinations described in the âcharacteristics: phenotypeâ field for each sample.
Project description:Dendritic cells (DC) play critical roles in central and peripheral T cell tolerance. DC found in the steady-state periphery undergo an homeostatic, tolerogenic, maturation that promotes interaction with naive T cells and induction of abortive responses. In contrast, thymic DC are thought to exist solely in an immature state. In this study, we show that XCR1+ thymic DC constitutively mature into a stage characterized by high levels of molecules involved in T cell activation. This unanticipated mature stage corresponded to a third of the XCR1+ thymic DC and fully accounted for their ability to cross-present self-antigens to developing T cells. Transcriptomic analysis of the XCR1+ DC found in thymus and steady-state periphery revealed that their maturation involves profound and convergent changes. Unexpectedly, maturation resulted in down-regulation of genes conferring their specific function on XCR1+ DC. Paradoxically, upon maturation, central and peripheral tolerogenic XCR1+ DC up-regulated many genes thought to drive pro-inflammatory T-cell responses. These events occur independtly of type I interferons and of the microlofora, since the same maturation pattern is observed in XCR1+ tDcs from control, Ifnar1-KO and germ-free mice. Thus, our results reveal that thymic XCR1+ DC undergo constitutive maturation and emphasize the common mechanisms operating for both central and peripheral tolerance induction by XCR1+ DC. DC were isolated from thymus organ as previously described (Luche et al., Eur J Immunol. 2011;41:2165-75.PMID: 21630253), from B6 SPF control, B6 germ-free and Ifnar1-KO mice. DC subsets were sorted by flow cytometry according to the marker combinations described in the Sample records' phenotype field.
Project description:Dendritic cells (DC) play critical roles in central and peripheral T cell tolerance. DC found in the steady-state periphery undergo an homeostatic, tolerogenic, maturation that promotes interaction with naive T cells and induction of abortive responses. In contrast, thymic DC are thought to exist solely in an immature state. In this study, we show that XCR1+ thymic DC constitutively mature into a stage characterized by high levels of molecules involved in T cell activation. This unanticipated mature stage corresponded to a third of the XCR1+ thymic DC and fully accounted for their ability to cross-present self-antigens to developing T cells. Transcriptomic analysis of the XCR1+ DC found in thymus and steady-state periphery revealed that their maturation involves profound and convergent changes. Unexpectedly, maturation resulted in down-regulation of genes conferring their specific function on XCR1+ DC. Paradoxically, upon maturation, central and peripheral tolerogenic XCR1+ DC up-regulated many genes thought to drive pro-inflammatory T-cell responses. Thus, our results reveal that thymic XCR1+ DC undergo constitutive maturation and emphasize the common mechanisms operating for both central and peripheral tolerance induction by XCR1+ DC.
Project description:Regulatory T (Treg) maintain the tumor microenvironment in an immunosuppressive state preventing effective anti-tumor immune response. A possible strategy to overcome Treg cell suppression focuses on OX40, a costimulatory molecule expressed constitutively by Treg cells while induced in activated effector T (Teff) cells. OX40 stimulation by the agonist mAb OX86 inhibits Treg cell suppression and boosts Teff cell activation. Here we uncover the mechanisms underlying the therapeutic activity of OX86 treatment dissecting its distinct effects on Treg and on effector memory T (Tem) cells, which are the most abundant CD4+ populations strongly expressing OX40 at the tumor site. In response to OX86, tumor-infiltrating Treg cells produced significantly less interleukin 10 (IL-10), possibly in relation to a decrease in the transcription factor IRF1. Tem cells responded to OX86 by upregulating surface CD40L expression, providing a licensing signal to dendritic cells (DCs). The CD40L/CD40 axis was required for Tem cell-mediated in vitro DC maturation and in vivo DC migration. Accordingly, OX86 treatment was no longer therapeutic in CD40 KO mice. In conclusion, following OX40 stimulation, blockade of Treg cell suppression and enhancement of the Tem cell adjuvant effect both concurred to free DCs from immunosuppression and to activate the immune response against the tumor. Total RNA obtained from sorted mouse FoxP3-GFP+ Treg activated in vitro with anti-CD3 in the presence of an OX40-agonist mAb (OX86) or isotype control.
Project description:Dendritic cells (DC) play critical roles in central and peripheral T cell tolerance. DC found in the steady-state periphery undergo an homeostatic, tolerogenic, maturation that promotes interaction with naive T cells and induction of abortive responses. In contrast, thymic DC are thought to exist solely in an immature state. In this study, we show that XCR1+ thymic DC constitutively mature into a stage characterized by high levels of molecules involved in T cell activation. This unanticipated mature stage corresponded to a third of the XCR1+ thymic DC and fully accounted for their ability to cross-present self-antigens to developing T cells. Transcriptomic analysis of the XCR1+ DC found in thymus and steady-state periphery revealed that their maturation involves profound and convergent changes. Unexpectedly, maturation resulted in down-regulation of genes conferring their specific function on XCR1+ DC. Paradoxically, upon maturation, central and peripheral tolerogenic XCR1+ DC up-regulated many genes thought to drive pro-inflammatory T-cell responses. These events occur independtly of type I interferons and of the microlofora, since the same maturation pattern is observed in XCR1+ tDcs from control, Ifnar1-KO and germ-free mice. Thus, our results reveal that thymic XCR1+ DC undergo constitutive maturation and emphasize the common mechanisms operating for both central and peripheral tolerance induction by XCR1+ DC.
Project description:We use single-cell RNA-seq to determine distinct selection phenotypes of 2 rare thymic Treg cell progenitors as well as mature thymic Treg cells
Project description:Regulatory T (Treg) maintain the tumor microenvironment in an immunosuppressive state preventing effective anti-tumor immune response. A possible strategy to overcome Treg cell suppression focuses on OX40, a costimulatory molecule expressed constitutively by Treg cells while induced in activated effector T (Teff) cells. OX40 stimulation by the agonist mAb OX86 inhibits Treg cell suppression and boosts Teff cell activation. Here we uncover the mechanisms underlying the therapeutic activity of OX86 treatment dissecting its distinct effects on Treg and on effector memory T (Tem) cells, which are the most abundant CD4+ populations strongly expressing OX40 at the tumor site. In response to OX86, tumor-infiltrating Treg cells produced significantly less interleukin 10 (IL-10), possibly in relation to a decrease in the transcription factor IRF1. Tem cells responded to OX86 by upregulating surface CD40L expression, providing a licensing signal to dendritic cells (DCs). The CD40L/CD40 axis was required for Tem cell-mediated in vitro DC maturation and in vivo DC migration. Accordingly, OX86 treatment was no longer therapeutic in CD40 KO mice. In conclusion, following OX40 stimulation, blockade of Treg cell suppression and enhancement of the Tem cell adjuvant effect both concurred to free DCs from immunosuppression and to activate the immune response against the tumor.