Project description:Murine γδ T cells include several effector subsets that fulfil distinct functional roles. In pathological conditions, such as cancer, some γδ T cell subsets are highly protective whereas other subsets may exacerbate disease. γδ T cells are programmed for their effector function during their development in the thymus. Investigations of γδ T cell development have been hampered by the scarcity of surface markers distinguishing different development stages. In this study, we found that addition of CD117, CD200 and CD371 to existing markers, allowed identification of seven distinct development stages (named A, B, C, D, E, F and G) present in both the Vγ1.1+ and Vγ2+ thymocyte subsets. We provide evidence for the existence of three distinct pathways leading to export of γδ T cells, two of which express high levels of CD24. These pathways are dominated by different TCRδ repertoires shaped by TCR signalling or lack thereof. Each pathway express distinct cytokine and transcription factor profiles associated with γδT1, γδNKT and adaptive γδ T cells. Thus, the identification of additional γδ T cell development stages in this study connects three distinct development pathways to the programming of three γδ T cell effector subsets.
Project description:In the mouse thymus, invariant γδ T cells are generated at well-defined times during development and acquire effector functions before exiting the thymus. However, whether such thymic programming can occur in human is not known. Here we analyzed human fetal and post-natal γδ thymocytes and investigated the role of hematopoietic-stem-and-precursor-cells (HSPC) in the generation of human γδ T cells. Unlike post-natal γδ thymocytes, fetal γδ thymocytes were functionally programmed (e.g. IFNγ, granzymes), expressed low levels of terminal-deoxynucleotidyl-transferase (TdT) and were highly enriched for invariant/public germline-encoded CDR3 sequences (TRGV8-TRJP1-CATWDTTGWFKIF, TRDV2-TRDD3-CACDTGGY and TRDV1-TRDD3-CALGELGD, previously shown to be expanded in cytomegalovirus infection) composed of short-homology-repeat-containing gene segments. Furthermore, these unique characteristics were due to an intrinsic property of fetal HSPC caused by high expression of the RNA-binding protein Lin28b. In conclusion, our data indicate that the human fetal thymus generates, in a HSPC/Lin28b-dependent manner, invariant γδ T cells with programmed effector functions.
Project description:Developmental thymic waves of innate-like and adaptive-like gd T cells have been described, but the current understanding of γδ T cell development is mainly limited to mouse models. Here, we combined single cell (sc) RNA gene expression and sc γδ T cell receptor (TCR) sequencing on fetal and pediatric γδ thymocytes in order to understand the ontogeny of human γδ T cells. Mature fetal γδ thymocytes were committed to either a type 1, a type 3 or type 2-like effector fate, independent from γδ T cell subset type (Vγ9Vδ2 vs nonVγ9Vδ2), and were enriched for public CDR3 features upon maturation. Strikingly, type 1, type 3 and type 2 cells expressed different CDR3 sequences and followed distinct developmental trajectories. In contrast, the pediatric thymus generated only a small effector subset that was highly biased towards Vγ9Vδ2 TCR usage and showed a mixed type 1/type 3 effector profile. Thus, our combined dataset of gene expression and detailed TCR information at the single-cell level defines γδ thymocyte development in human and provides a resource for further study.
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:Organismal ageing is associated with loss of immune function and higher incidence of cancer. Whether the γδ T cell pool changes upon organismal ageing is not known. In this study we have characterized γδ T cells in peripheral lymph nodes from old and young mice. We found that the γδ T cell pool is severely altered in old mice. The IL-17 producing γδ lineage becomes dominating while IFN-γ producing γδ1 T cells are declining. γδTCR sequencing revealed no collapse in diversity but oligoclonal expansions in Vγ4 γδ17 subsets. Pro-tumourigenic invariant Vγ6 cells are present only in aged lymph nodes, represent the majority of γδ T cells in the tumour, and are associated with faster tumour progression.
Project description:Our team had previously explored the potential of expanding cord blood (CB) derived γδ T cells (CB-gdT) as well as their corresponding ability to target primary acute myeloid leukemia (AML) cells. Using a feeder cell line-based in vitro expansion protocol, we achieved a clinically relevant scale expansion of γδ T cells over a period of 14 days. These cells exhibit variable degree of potency against a range of human AML cell lines and primary patient samples. In order to dissect the cellular and molecular programs governing the activation, differentiation and functional states of our in vitro expanded CB-gdT, we performed multiplex single cell sequencing analysis using the 10X Genomics Chromium System. After initial quality check and filtering, data from a total of 4,276 cells were retrieved. Among which, we identified 742 unique TCRγδ clonotypes, representing 18.6% of the starting 4,000 FACS purified γδ T cells seeded for expansion. Consistent to our FACS analysis, Vδ1 is the predominant TRD chain in the expanded cultures, accounting for 61.2% of all clones. Based on uniform manifold approximation and projection for dimension reduction (UMAP), all cells were clustered into 11 subsets. Key cytotoxic genes including GZMB, GZMA and NKG7 were all highly expressed across all clusters, indicating that the expanded cells were indeed functionally cytotoxic. Comparing against multiple curated gene sets, we have identified 3 main subsets of γδ T cells: the Proliferative, Cytotoxic γδ T cells (P-CT), Differentiated Cytotoxic γδ T cells (D-CT) and Late Activated Cytotoxic γδ T cells (LA-CT). P-CT (~46% of all cells) shows an expression profile positively associated with cell proliferation as well as increased cell surface expression of memory T cell markers CD27, CCR7 and CD62L. Similar to cytotoxic genes, genes associated with TCR signaling and interferon response were found to be expressed across all cell clusters, yet with elevated levels in D-CT and LA-CT. Furthermore, cell surface expression of different NK receptors including NKG2D, DNAM1 and NKp30 are more enriched in LA-CT compared to the other 2 subsets, suggesting the acquisition of additional NK receptor related functions in this group of cells. Consistent with the concept of progressive γδ T cell differentiation and activation in culture, we found that in 85 (11.5%) of the γδ T cell clones bearing more than 10 cells each, all clones contain cells distributed across the 3 different γδ T cell subsets. This is the first report on single cell immune profiling of in vitro expanded gdT cells derived from human CB.
Project description:Abstract: Bovine tuberculosis (bTB), caused by infection with Mycobacterium bovis, continues to cause significant issues for the global agriculture industry as well as for human health. An incomplete understanding of the host immune response contributes to the challenges of control and eradication of this zoonotic disease. In this study, high-throughput bulk RNA sequencing (RNA-seq) was used to characterize differential gene expression in γδ T cells – a subgroup of T cells which bridge innate and adaptive immunity and have specific anti-mycobacterial response mechanisms. γδ T cell subsets are classified on the basis of expression of a pathogen-recognition receptor known as Workshop Cluster 1 (WC1) and we hypothesised that bTB infection may alter the phenotype and function of specific γδ T cell subsets. Peripheral blood was collected from naturally M. bovis-infected (positive for single intradermal comparative tuberculin test (SICTT) and IFN-γ ELISA) and age- and sex-matched, non-infected control Holstein-Friesian cattle. γδ T subsets were isolated using fluorescence activated cell sorting (n = 10-12 per group) and high-quality RNA extracted from each purified lymphocyte subset (WC1.1+, WC1.2+, WC1- and γδ-) was used to generate transcriptomes using bulk RNA-seq (n = 6 per group, representing a total of 48 RNA-seq libraries). Relatively low numbers of differentially expressed genes (DEGs) were observed between most cell subsets; however, 163 genes were significantly differentially expressed in the M. bovis-infected compared to control groups for the WC1.1+ γδ T cell compartment (Log 2 FC ≥ 1.5 and FDR P adj ≤ 0.1). The majority of these DEGs (146) were significantly increased in expression in cells from the bTB+ cattle and included genes encoding transcription factor (TBX21 and EOMES), chemokine receptors (CCR5 and CCR7), granzymes (GZMA, GZMM and GZMH) and multiple killer cell immunoglobulin-like receptors (KIR) indicating cytotoxic functions. Biological pathway overrepresentation analysis revealed enrichment of genes with multiple immune functions including cell activation, proliferation, chemotaxis and cytotoxicity of lymphocytes. In conclusion, WC1.1+ γδ T cells have been proposed as major regulatory cell subset in cattle, and we provide evidence for preferential differential activation of this specific subset in cattle naturally infected with M. bovis. Understanding the role of these critical immune cells during mycobacterial infection contributes to our understanding of host immunity to bTB and identifies multiple novel cytotoxic functions of WC1.1+ γδ T cells.
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: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.