ABSTRACT: TCR signal strength controls thymic differentiation of discrete proinflammatory γδT cell subsetsistinct TCR signal strength requirements in the thymus
Project description:Conventional CD4 and CD8 single positive T cell lineages constitute the main differentiation pathway in the thymus. In human thymus, a minor TCRαβ differentiation pathway diverges from the early double positive stage, consisting of CD10+ PD-1+ cells. These cells are phenotypically and functionally similar to murine agonist-selected intraepithelial T lymphocyte precursors (IELps) which home to the small intestine. Here, the progeny of the human agonist-selected IEL lineage was identified in antigen-inexperienced cord blood (CB) with a polyclonal T cell receptor (TCR) repertoire exhibiting a bias towards early TCR alpha chain rearrangements and elevated autoreactive indices. Single-cell RNA sequencing allowed further delineation of this unconventional lineage in CB. Trajectory analysis, along with TCR repertoire analysis, transcriptomics and proteomics, suggests a precursor-progeny relationship with the thymic IELps. The distinct, heterogeneous CB population can now be defined as CD3+ TCRαβ+ CD4- CCR7- CD26-. Besides recent thymic emigrants, this population also consists of newly identified effector clusters and previously described populations: the suppressive NK receptor expressing CD8+ Treg population, the KIR/NKG2A+ EOMES+ virtual memory population and the CD8αα+ T cell populations. The population shows a discriminating stable HELIOS expression and is exclusively able to downregulate CD8β expression, resulting in double negative T cells. The functional properties of this population suggest that the cells expand on inflammatory cues and exert cytotoxic and proinflammatory activity.
Project description:The murine thymus produces discrete γδ T cell subsets making either IFN-γ or IL-17, but the role of the TCR in this developmental process remains controversial. Here we generated a non-transgenic and polyclonal model of reduced TCR expression and signal strength selectively on γδ T cells. Mice haploinsufficient for both CD3γ and CD3δ (CD3DH) showed normal αβ thymocyte subsets but specific defects in γδ T cell development, namely impaired differentiation of IL-17-producing embryonic Vγ6+ (but not adult Vγ4+) γδ T cells and a marked depletion of IFN-γ-producing CD122+ NK1.1+ (Vγ1-biased) γδ T cells throughout life. As result, adult CD3DH mice showed defective peripheral IFN-γ responses and were resistant to experimental cerebral malaria. Thus, strong TCR signaling is required within specific developmental windows with distinct Vγ usage and differential cytokine production by effector γδ T cell subsets. We investigated the transcriptional changes associated with reduced TCRγδ signaling in the CD3DH model. Transcriptome-wide analysis of FACS-purified CD3DH or WT γδ thymocytes from E18 or 6-week was carried looking for patterns of gene expression during ontogeny
Project description:The interdependence of selective cues during development of regulatory T (Treg) cells in the thymus and their suppressive function remains incompletely understood. Here we analyzed this interdependence by taking advantage of highly dynamic changes of miR-181a/b-1 during late T-cell development with very high levels of expression during thymocyte selection followed by massive downregulation in the periphery. Loss of miR-181a/b-1 resulted in inefficient de novo generation of Treg cells in the thymus, but simultaneiously permitted homeostatic expansion in the periphery in the absence of competition. Modulation of T-cell receptor (TCR) signal strength in vivo indicated that miR-181a/b-1 controlled Treg cell formation via establishing adequate signaling thresholds. Unexpectedly, miR-181a/b-1-deficient Treg cells displayed elevated suppressive capacity in vivo, in line with elevated levels of CTLA-4 protein, but not mRNA, in thymic and peripheral Treg cells. Therefore, we propose that intrathymic miR-181a/b-1 controls development of Treg cells and imposes a developmental legacy on their peripheral function.
Project description:The murine thymus produces discrete γδ T cell subsets making either IFN-γ or IL-17, but the role of the TCR in this developmental process remains controversial. Here we generated a non-transgenic and polyclonal model of reduced TCR expression and signal strength selectively on γδ T cells. Mice haploinsufficient for both CD3γ and CD3δ (CD3DH) showed normal αβ thymocyte subsets but specific defects in γδ T cell development, namely impaired differentiation of IL-17-producing embryonic Vγ6+ (but not adult Vγ4+) γδ T cells and a marked depletion of IFN-γ-producing CD122+ NK1.1+ (Vγ1-biased) γδ T cells throughout life. As result, adult CD3DH mice showed defective peripheral IFN-γ responses and were resistant to experimental cerebral malaria. Thus, strong TCR signaling is required within specific developmental windows with distinct Vγ usage and differential cytokine production by effector γδ T cell subsets.
Project description:Various subsets of invariant natural killer T (iNKT) cells with different cytokine productions develop in the mouse thymus, but the factors driving their differentiation remain unclear. Here we show that hypomorphic alleles of Zap70 or chemical inhibition of Zap70 catalysis lead to an increase of IFN-g-producing iNKT cells (NKT1 cells), suggesting NKT1 cells may require a lower TCR signal threshold. Zap70 mutant mice develop IL-17-dependent arthritis. iNKT cells and therapeutic induction of IFN-g secretion by activating iNKT cells are protective in this model, but the representation of IFNg versus IL-17 secreting iNKT cells in the joint change in favor of IL-17 producers as disease worsened. NKT1 cells are also present in the synovial fluid of arthritis patients, where they could be beneficial. Our data therefore suggest that TCR signal strength during thymic differentiation may influence not only IFNg production, but also the protective function of iNKT cells in arthritis.
Project description:Various subsets of invariant natural killer T (iNKT) cells with different cytokine productions develop in the mouse thymus, but the factors driving their differentiation remain unclear. Here we show that hypomorphic alleles of Zap70 or chemical inhibition of Zap70 catalysis lead to an increase of IFN-g-producing iNKT cells (NKT1 cells), suggesting NKT1 cells may require a lower TCR signal threshold. Zap70 mutant mice develop IL-17-dependent arthritis. iNKT cells and therapeutic induction of IFN-g secretion by activating iNKT cells are protective in this model, but the representation of IFNg versus IL-17 secreting iNKT cells in the joint change in favor of IL-17 producers as disease worsened. NKT1 cells are also present in the synovial fluid of arthritis patients, where they could be beneficial. Our data therefore suggest that TCR signal strength during thymic differentiation may influence not only IFNg production, but also the protective function of iNKT cells in arthritis.
Project description:IL-2 inducible tyrosine kinase (Itk) is a Tec family non-receptor tyrosine kinase that is known to regulate T cell receptor signal strength (TcR) and T cell development and differentiation. TcR signal strength and antigen affinity are parameters known to regulate the development of CD8+ T cell memory. However, the intersection between TcR signal strength and antigen affinity on CD8+ memory T cell development remains unclear. Therefore, we compared the transcriptomes of WT and Itk-/- OT-1/Rag-/- CD8+ T cells at day 0 and day 7 following infection with Listeria monocytogenes expressing the SIINFEKL (N4) or SIITFEKL (T4) OVA peptide variant (different affinities for TcR) by RNA sequencing.
Project description:During T cell development in the thymus, negative selection eliminates autoreactive and potentially harmful T cells, leading to central tolerance. This process, involves specific apoptosis programs thought to be governed by the transcription factor Nur77. To analyze the genetic pathways involved in thymic negative selection and to point to new genes involved in thymic selection, we performed a high throughput temporal expression profiling of thymocytes from HNT-TCR transgenic mice undergoing specific peptide-mediated thymic negative selection, using oligonucleotide microarrays. We used HNT-TCR transgenic mice that are on a B10D2 background and express a transgenic TCR (V beta 8), specific for the HA peptide (HNTNGVTAACSHE) presented by MHC class II I-A^d. In this model of thymic negative selection, a single injection of the specific HA peptide induces massive and synchronized deletion of thymocytes. In this study, we analyzed the dynamically regulated genes over a 24 hours period, with a focus on the early time points of 3 and 6 hours after peptide injection.