Project description:Three major phenotypically and functionally distinct invariant Natural Killer T (iNKT) cell subsets (iNKT1, iNKT17 and iNKT2), each with propensity to traffic to different tissues and to secrete different cytokines upon activation, have been defined. These fate assignments can be conferred upon iNKT cells during development in the thymus, but the cues that direct these decisions remain unclear. Here, we show that T cell antigen receptor (TCR) signal strength governs the development of iNKT cell subsets in the thymus, with high signaling strength necessary for iNKT2 and iNKT17 development. Alteration of TCR diversity and/or signaling dramatically diminished iNKT2 and iNKT17 cell subset development in a cell intrinsic manner. Decreased TCR signaling affected the persistence of Egr2 expression and the upregulation of PLZF both in vivo and in vitro. Genome-wide chromatin accessibility analysis revealed subset-specific activity of regulatory elements associated with unique signatures of transcription factor binding sites. NFAT and Egr binding motifs were found preferentially enriched in chromatin regulatory regions specifically accessible in iNKT2 cells that were lost in iNKT2 cells that had developed with reduced TCR signaling. Altogether, these data suggest a model of iNKT cell subset development where variable TCR signaling induces changes in chromatin accessibility at NFAT and Egr binding sites which exerts a determinative influence on the dynamic of gene enhancer accessibility that affects the developmental fate of iNKT cells.
Project description:Three major phenotypically and functionally distinct invariant Natural Killer T (iNKT) cell subsets (iNKT1, iNKT17 and iNKT2), each with propensity to traffic to different tissues and to secrete different cytokines upon activation, have been defined. These fate assignments can be conferred upon iNKT cells during development in the thymus, but the cues that direct these decisions remain unclear. Here, we show that T cell antigen receptor (TCR) signal strength governs the development of iNKT cell subsets in the thymus, with high signaling strength necessary for iNKT2 and iNKT17 development. Alteration of TCR diversity and/or signaling dramatically diminished iNKT2 and iNKT17 cell subset development in a cell intrinsic manner. Decreased TCR signaling affected the persistence of Egr2 expression and the upregulation of PLZF both in vivo and in vitro. Genome-wide chromatin accessibility analysis revealed subset-specific activity of regulatory elements associated with unique signatures of transcription factor binding sites. NFAT and Egr binding motifs were found preferentially enriched in chromatin regulatory regions specifically accessible in iNKT2 cells that were lost in iNKT2 cells that had developed with reduced TCR signaling. Altogether, these data suggest a model of iNKT cell subset development where variable TCR signaling induces changes in chromatin accessibility at NFAT and Egr binding sites which exerts a determinative influence on the dynamic of gene enhancer accessibility that affects the developmental fate of iNKT cells.
Project description:Development of T cells is controlled by the signal strength of the TCR. The scaffold protein Kinase D-interacting substrate of 220 kDa (Kidins220) binds to the TCR; however, its role in T cell development was unknown. Here, we show that T cell-specific Kidins220 knock-out (T-KO) mice have strongly reduced invariant natural killer T (iNKT) cell numbers and modest decreases in conventional T cells. Enhanced apoptosis due to increased TCR signaling in T-KO iNKT thymocytes of developmental stage 2 and 3 shows that Kidins220 downregulates TCR signaling at these stages. scRNAseq indicated that the transcription factor Aiolos is downregulated in Kidins220-deficient iNKT cells. Analysis of an Aiolos KO demonstrated that Aiolos is a downstream effector of Kidins220 during iNKT cell development. In the periphery, T-KO iNKT cells show reduced TCR signaling upon stimulation with α-galactosylceramide, suggesting that Kidins220 promotes TCR signaling in peripheral iNKT cells. Thus, Kidins220 reduces or promotes signaling dependent on the iNKT cell developmental stage.
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 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:Single-cell TCR-seq analysis of murine thymic iNKT cells from three independent BALB/c mice and three independent Cd80/Cd86 (B7)-deficient mice
Project description:γδ T-cells form an integral arm of the immune system through their rapid and potent effector functions, and are critical players during both protective and destructive immunity. However, the factors that dictate γδ T-cell functional programming in vivo remain to be fully elucidated. Here, we employed RBPJ-inducible and KN6-transgenic mice to assess the roles of ontogenic timing, T-cell receptor (TCR) signal strength, and Notch signaling in the generation of γδ T-cell functional subsets in vivo. We found skewed generation of Vγ1+ cells toward the PLZF+ γδ T-cell lineage at the fetal stage. Similarly, generation of interleukin (IL)-17 producing γδ T-cells was favored during, although not exclusive to, the fetal stage. Strong TCR signals, in conjunction with Notch, were necessary for the generation of IL-4 producing γδ T-cells. Conversely, weak TCR signals were amenable for the generation of IL-17 producing γδ T-cells, which was Notch-independent. Additionally and surprisingly, Notch signaling was also dispensable for peripheral γδ T-cell IL-17 production. Thus, our results precisely defined the roles of ontogenic timing, TCR signal strength, and Notch signaling in γδ T-cell functional programming in vivo.
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.