MR1-restricted T cell clonotypes are associated with “resistance” to Mycobacterium tuberculosis infection
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ABSTRACT: T cells are required for protective immunity against Mycobacterium tuberculosis. We recently described a cohort of Ugandan household contacts of tuberculosis cases who appear to “resist” M. tuberculosis infection (resisters; RSTRs) and showed that these individuals harbor IFN-γ–independent T cell responses to M. tuberculosis–specific peptide antigens. However, T cells also recognize nonprotein antigens via antigen-presenting systems that are independent of genetic background, known as donor-unrestricted T cells (DURTs). We used tetramer staining and flow cytometry to characterize the association between DURTs and “resistance” to M. tuberculosis infection. Peripheral frequencies of most DURT subsets were comparable between RSTRs and latently infected controls (LTBIs). However, we observed a 1.65-fold increase in frequency of MR1-restricted T (MR1T) cells among RSTRs in comparison with LTBIs. Single-cell RNA sequencing of 18,251 MR1T cells sorted from 8 donors revealed 5,150 clonotypes that expressed a common transcriptional program, the majority of which were private. Sequencing of the T cell receptor α/T cell receptor δ (TCRα/δ) repertoire revealed several DURT clonotypes were expanded among RSTRs, including 2 MR1T clonotypes that recognized mycobacteria-infected cells in a TCR-dependent manner. Overall, our data reveal unexpected donor-specific diversity in the TCR repertoire of human MR1T cells as well as associations between mycobacteria-reactive MR1T clonotypes and resistance to M. tuberculosis infection.
Project description:Disease activity of autoimmune disorders such as multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE) is temporarily suppressed by pregnancy. However, whether disease amelioration is due to non-specific immunomodulation or mediated by antigen-specific regulation of disease-causing conventional T cells (Tcon) and immuno- suppressive regulatory T cells (Treg), remains elusive. In the present study, we systematically analyzed changes of the T cell receptor (TCR) β repertoire driven by EAE and pregnancy using TCR sequencing. We demonstrate that EAE, but not pregnancy, robustly increased TCR repertoire clonality in both peripheral Tcon and Treg. Notably, pregnancy was required for the expansion of Treg harboring the dominant EAE-associated TRBV chain 13.2 and increased the frequency of EAE-associated clonotypes within the Treg compartment. Our findings indicate that pregnancy supports the expansion of Treg clonotypes that are equipped to recognize EAE- associated antigens. These Treg are thereby particularly suited to control corresponding encephalitogenic Tcon responses and likely contribute to pregnancy-associated protection in autoimmunity.
Project description:We designed a lineage tracing method to label a wave of T cells produced in the thymus of young. TCR repertoire analysis revealed that the lineage-tracked CD4 memory-like T cells and T regulatory cells exhibited age-dependent enrichment of shared clonotypes, indicating that antigen matched T regulatory cells are involved in maintaining the tolerant status of long-lived T cell clones. Furthermore, these shared clonotypes were found across different mice maintained in the same housing condition mice. Examination of antigen-specificity of aging-tracking T-cell subtype.
Project description:Rationale: Tuberculosis has a devastating impact on global health by claiming nearly 1.4 million lives each year. During infection Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, produces heterogenous populations some of which don’t produce colonies on agar but grow in liquid media and often require supplementation with culture supernatants or recombinant Resuscitation-promoting factor, thus defined as differentially culturable bacilli. Objectives: to evaluate whether exposure to nitric oxide (NO), a well-known host defence molecule, alters mycobacterial growth phenotypes and drives generation of Rpf-dependent differentially culturable bacilli. Methods: a novel NO donor was synthesised and tested against Mtb and Mycobacterium bovis BCG in vitro, followed by growth assays, flow cytometry analysis and assessment of transcriptomic responses. Resuscitation-promoting factor (Rpf) inhibitors were used to characterise the role of Rpf proteins in the reactivation of NO-treated mycobacteria. Mycobacterial phenotypes were also investigated during infection of THP-1 macrophages activated with retinoic acid and vitamin D3. Measurements and Main Results: differentially culturable mycobacteria were generated after exposure to the novel NO donor or during infection of activated THP-1 cells. Resuscitation of these differentially culturable bacilli was largely abolished by specific Rpf inhibitors. Transcriptomic analysis revealed redox-associated stress signatures mediated by SigH and SigF, with significant down-regulation of ribosome and cell wall architecture genes, including rpfA, rpfB and rpfE, and induction of genes involved in response to thiol stress, sulphur metabolism and iron acquisition. Conclusion: Our study provides mechanistic insights into the generation of Rpf-dependent Mtb during tuberculosis and outlines a critical role of NO in this process.
Project description:To elucidate the T cell epitopes of SARS-CoV-2, we stimulated human PBMCs from healthy donors and convalescent COVID-19 patients with various SARS-CoV-2 antigens, sorted the activated T cells and performed sc-RNA and -TCR sequencing. We obtained thousands of T cell clonotypes that responded to SARS-CoV-2 antigens, and identified the epitopes and restricting HLAs of several clonotypes that were significantly expanded in the COVID-19 patients.
Project description:Diversity of the T-cell receptor (TCR) repertoire is central to adaptive immunity. The TCR is composed of α and β chains, encoded by the TRA and TRB genes, of which the variable regions determine antigen specificity. To generate novel biological insights into the complex functioning of immune cells, combined capture of variable regions and single-cell transcriptomes provides a compelling approach. Recent developments enable the enrichment of TRA and TRB variable regions from widely used technologies for 3’-biased single-cell RNA-sequencing (scRNA-seq). However, a comprehensive computational pipeline to process TCR-enriched data from 3’ scRNA-seq is not available. Here we present an analysis pipeline to process TCR variable regions enriched from 3’ scRNA-seq cDNA. The tool reports TRA and TRB nucleotide and amino acid sequences linked to cell barcodes, enabling the reconstruction of T-cell clonotypes with associated transcriptomes. We demonstrate the software using peripheral blood mononuclear cells (PBMCs) from a healthy donor and detect TCR sequences in a high proportion of single T-cells. Detection of TCR sequences is negligible in non-T-cell populations, demonstrating specificity. Finally, we show that TCR clones are larger in CD8 Memory T-cells than other T-cell types, indicating an association between T-cell clonotypes and differentiation states.
Project description:<p>Diversity and size of the antigen-specific T cell receptor (TCR) repertoire are two critical determinants for successful control of chronic infection. Varicella zoster virus (VZV) that establishes latency during childhood is able to escape control mechanisms, in particular with increasing age. We examined the TCR diversity of VZV-specific CD4 T cells in individuals older than 50 years by studying three identical twin pairs and three unrelated individuals before and after vaccination with live attenuated VZV. While all individuals had a small number of dominant T cell clones, the breadth of the VZV-specific repertoire differed markedly among different individuals. A genetic influence was seen for the sharing of individual TCR sequences from antigen-specific cells, but not for repertoire richness or the selection of clonal dominance. VZV vaccination favored the expansion of infrequent VZV-specific TCRs including those from naïve T cells while leaving dominant T cell clones mostly unaffected.</p>
Project description:Generating balanced populations of CD8+ effector and memory T cells is necessary for immediate and durable immunity to infections and cancer. Yet, a definitive understanding of how a diverse CD8+ T cell repertoire differentiates remains unclear. We identified several hundred TCR clonotypes that constitute the polyclonal response against a single antigen and found that a majority of TCR clonotypes were highly biased towards memory or effector fate. TCR-intrinsic biases were not stochastic and were dominant over environmental cues. Differential gene expression analysis of memory- or effector-biased TCR clonotypes showed bifurcation of differential fates at the early effector stage. Additionally, phylogenetic analysis revealed that memory-biased clonotypes retain their fate preferences in subclonal populations but effector-biased subclones can switch to memory fate. Our study highlights that the polyclonal CD8+ T cell response is a composite of unbiased and biased clonotypes with varying capacity to incorporate environmental cues in their cell fate decisions.
Project description:Immunogenetic studies in CLL revealed clonal expansions of T cells and shared T cell clonotypes between different patients, strongly implying clonal selection by antigens. Recurrent genomic aberrations associated with distinct abnormal expression profiles could represent an alternative source of potent immunogenic neoepitopes that might shape the T cell receptor (TR) gene repertoire in CLL. On these grounds, here we interrogated the TR gene repertoire of CLL patients with different genomic aberration profiles with the aim to identify unique signatures that would allude to distinct antigen selection pressures.The study group included 44 untreated CLL patients with who were categorized in 5 subgroups defined by a unique genomic aberration, as follows: +12, n=17; del(11q), n=10; del(13q), n=7; TP53mut, n=5; NOTCH1mut, n=5. Starting material was RNA extracted from blood mononuclear cells. TRBV-TRBD-TRBJ gene rearrangements were RT-PCR amplified and subjected to paired-end next generation sequencing (NGS). Bioinformatics analysis with a purpose-build pipeline and in silico prediction models were used for the profiling of the TR gene repertoire and the identification of neoepitope-specific TR clonotypes, respectively.
Project description:Purpose: Despite the well-established association between T cell-mediated inflammation and non-ischemic heart failure (HF), the specific mechanisms triggering T cell activation during the progression of HF and the antigens involved are poorly understood. We hypothesized that clonal expansion of CD4+ T cell in response to cardiac neoantigens promote the progression of HF. Methods: We used transverse aortic constriction (TAC) in mice to trigger HF and profiled the TCR repertoire by mRNA sequencing of CD4+ T cells from 3 pooled Nur77GFP reporter mice, which transiently express GFP upon TCR engagement. We performed TCR clonal analysis of 5000 TCR-activated GFP+CD4+ T cells sorted from the LV, and 5000 CD4+ T cells sorted from the thymus, the inguinal lymph nodes (iLNs) and the heart-draining mediastinal lymph nodes (mLNs) by bulk RNA sequencing of the TCR beta chain after 8wks of TAC surgery. Paired‐end 300 base pair reads were obtained by Illumina sequencing and aligned and assembled using MiXCR software. Results: As expected, the greatest number of unique TCR beta clonotypes (4412 clones) – and therefore the highest TCR diversity – was identified in the thymus. The heart draining mLNs showed a much lower degree of TCR clonal diversity relative to the peripheral iLNs, suggesting that cardiac antigen-driven clonal expansion occurs at the mLNs that directly drain the heart. TCR-activated GFP+CD4+ T cells in the LV represented even lower TCR diversity relative to other sites. Conclusion: Collectively, our study demonstrates that in response to cardiac pressure overload, CD4+ T cells clonally expand in the heart-draining mLN; whilst a limited repertoire of CD4+ T cell clones engage endogenous antigens in the heart.
Project description:T-cell landscape differences between cutaneous squamous cell carcinoma (cSCC) tumors in immune competent (SCC in IC) and immunocompromised organ transplant recipients (TSCC in OTR) are unclear. We developed an analytical method to define tumor infiltrating lymphocyte (TIL) phenotype in cSCC from immune competent and immune suppressed patients using single-cell TCR sequencing and gene expression data. TSCC exhibits reduced proportions of cytotoxic and naïve TILs and similar numbers of regulatory TILs. Fewer, more heterogeneous TCR clonotypes are observed in TIL from OTR. Most TCR sequences for top ten clonotypes correspond to known antigens, while 24% correspond to putative neoantigens. OTR show increased cSCC events over 12 months possibly due to reduced cytotoxic T-cells. Our novel method of barcoding CD8+ T-cells is the first providing gene expression and TCR sequences in cSCC. Knowledge regarding putative antigens recognized by TCRs with phenotypic function of T-cells bearing those TCRs could facilitate personalized cSCC treatments.