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Single cell RNAseq of human TCRVdelta 1 and TCRVdelta 2 gammadelta T lymphocytes purified from healthy adults blood

ABSTRACT: γδ T lymphocytes represent ~1% of human PBMC and even more cells in most tissues of vertebrates. Although they have important anticancer functions, most current scRNA-Seq studies do not identify γδ T lymphocytes since their transcriptomes at the single cell level are unknown. Here we show that high resolution clustering of large scRNA-Seq data sets and a combination of gene signatures allow the specific detection of human γδ T lymphocytes and identification of their TCRVδ1 and TCRVδ2 subsets in large data sets from complex cell mixtures. In t-SNE plots from blood and tumor samples, the few γδ T lymphocytes appear collectively embedded between cytotoxic CD8 T and NK cells. Their TCRVδ1 and TCRVδ2 subsets form close yet distinct sub-clusters respectively neighbouring NK and CD8 T cells owing to expression of shared and distinct cytotoxic maturation genes. Similar pseudo-time maturation trajectories of TCRVδ1 and TCRVδ2 γδ T lymphocytes were discovered, unveiling in both subsets an unattended pool of TEMRA cells with preserved proliferative capacity, a finding confirmed by in vitro proliferation assays. Overall, the single cell transcriptomes of thousands of individual gd T lymphocytes from different CMV+ and CMV- donors reflect cytotoxic maturation stages driven by the immunological history of donors. This landmark study establishes the rationale for identification, subtyping and deep characterization of human γδ T lymphocytes in further scRNA-Seq studies of complex tissues in physiological and disease conditions.

ORGANISM(S): Homo sapiens

PROVIDER: GSE128223 | GEO | 2019/05/01

REPOSITORIES: GEO

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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.

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Single cell RNAseq of human TCRVdelta 1 and TCRVdelta 2 gammadelta T lymphocytes purified from healthy adults blood

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