Project description:In human studies, mononuclear cells from peripheral blood (PBMC) often serve as a source of clinical study markers. Therefore, it is essential to understand to what extent phenotypes of PBMCs reflect their tissue-resident equivalents. In order to determine the heterogeneity of T-follicular helper (TFH) cells in peripheral blood versus tonsils, CD3+CD4+CD45RA–CXCR5+ cells of both origins were sorted and transcriptomes, TCR repertoires and cell-surface protein expression were analysed by single-cell RNA sequencing, flow cytometry and immunohistochemistry. Four subsets of TFH cells with classical T-follicular gene expression patterns were mostly found in tonsils. Interestingly, however, all circulating CD3+CD4+CXCR5+ T-cell subpopulations also appeared in tonsils. Still, when circulating, cells of the same cluster rather displayed markers of proliferation and migration, whereas their tonsillar counterparts exhibited known TFH characteristics resembling bona fide germinal center-typical TFH cell subtypes. Surprisingly, one distinct and oligoclonal CD4+CXCR5+ subpopulation displayed pronounced cytotoxic properties. Those ‘killer TFH (TFK) cells’ were found among PBMCs as well as tonsillar cells but were located outside of germinal centers. Accordingly, they were the only CD4+CXCR5+ T-cell subtype in tonsils featuring transcripts for CXCR3 and PSLG1. They appeared terminally differentiated and could be distinguished from all other TFH subsets by expression of NKG7 (TIA-1), granzymes, perforin, CCL5, CCR5, EOMES, CRTAM and CX3CR1. This hitherto undescribed subpopulation is indicative for chronic infection and inflammation and therefore is a valuable candidate to be included in any CD4+CXCR5+ TFH cell assessment.
Project description:In clinical situations, peripheral blood accessible CD3+CD4+CXCR5+ T-follicular helper (TFH) cells may have to serve as a surrogate indicator for dysregulated germinal center responses in tissues. To determine the heterogeneity of TFH cells in peripheral blood versus tonsils, CD3+CD4+CD45RA-CXCR5+ cells of both origins were sorted. Transcriptomes, TCR repertoires and cell-surface protein expression were analysed by single-cell RNA sequencing, flow cytometry and immunohistochemistry. Reassuringly, all blood-circulating CD3+CD4+CXCR5+ T-cell subpopulations also appear in tonsils, there with some supplementary TFH characteristics, while peripheral blood-derived TFH cells display markers of proliferation and migration. Three further subsets of TFH cells, however, with bona fide T-follicular gene expression patterns, are exclusively found in tonsils. One additional, distinct and oligoclonal CD4+CXCR5+ subpopulation presents pronounced cytotoxic properties. Those 'killer TFH (TFK) cells' can be discovered in peripheral blood as well as among tonsillar cells but are located predominantly outside of germinal centers. They appear terminally differentiated and can be distinguished from all other TFH subsets by expression of NKG7 (TIA-1), granzymes, perforin, CCL5, CCR5, EOMES, CRTAM and CX3CR1. All in all, this study provides data for detailed CD4+CXCR5+ T-cell assessment of clinically available blood samples and extrapolation possibilities to their tonsil counterparts.
Project description:In response to infection, antigen-specific CD8+ T cells are primed in the T cell zone of secondary lymphoid organs and differentiate into cytotoxic effector T (TC) cells. Concurrently, CD4+ T cells differentiate into follicular helper T (TFH) cells that localize to B cell follicles and promote protective antibody responses. During unresolved infections, however, some viruses including human immunodeficiency virus (HIV) or Epsteinâ??Barr virus (EBV) escape immune control and persist in TFH cells and B cells, respectively. Exclusion of Tc cells from B cell follicles is thought to be a major mechanism of immune evasion. New strategies are therefore needed to eradicate infected cells in follicles for a permanent cure. Using mouse infection models and human samples, we here identify a specialized group of TC cells expressing the chemokine receptor CXCR5 that can selectively enter B cell follicles and eradicate infected TFH and B cells. We demonstrate that differentiation of these cells, which we term follicular cytotoxic T (TFC) cells, requires the transcription factors Bcl6, E2A and Tcf1, whereas the transcriptional regulators Blimp1, Id3 and Id2 inhibit their development. We demonstrate that Blimp1 and E2A directly regulate Cxcr5 expression, and together with Bcl6 and Tcf1 form a transcriptional circuit that guides the TFC differentiation. The identification of a follicular subset of TC cells has far reaching implications for developing better strategies for the control of infections that target B cells and TFH cells and for the eradication of B cell derived malignancies. There is no associated input. The E2A Bio-ChIP-seq was performed with total thymocytes from Tcf3Bio/Bio Rosa26BirA/BirA mice
Project description:Lymphocytic Choriomeningitis Virus (LCMV) specific CD8+ T cells (P14) were transferred into congenic WT mice followed by LCMV(DOCILE) infection. CXCR5-expressing (CXCR5+) or CXCR5 non-expressing (CXCR5-) P14 were purified on day 8 after infection, and total mRNA were sequenced from these populations. mRNA of P14 from uninfected mice (Naive P14) was also sequenced. Examination of mRNA level in CXCR5 expressing P14 (CXCR5+P14) and non-expressing P14 (CXCR5-P14) from LCMV infected mice day 8 post infection. mRNA of P14 from uninfected mice (Naïve P14) was also examined.
Project description:Lymphocytic Choriomeningitis Virus (LCMV) specific CD8+ T cells (P14) were transferred into congenic WT mice followed by LCMV(DOCILE) infection. CXCR5-expressing (CXCR5+) or CXCR5 non-expressing (CXCR5-) P14 were purified on day 8 after infection, and total mRNA were sequenced from these populations. mRNA of P14 from uninfected mice (Naive P14) was also sequenced.
Project description:In response to infection, antigen-specific CD8+ T cells are primed in the T cell zone of secondary lymphoid organs and differentiate into cytotoxic effector T (TC) cells. Concurrently, CD4+ T cells differentiate into follicular helper T (TFH) cells that localize to B cell follicles and promote protective antibody responses. During unresolved infections, however, some viruses including human immunodeficiency virus (HIV) or Epstein–Barr virus (EBV) escape immune control and persist in TFH cells and B cells, respectively. Exclusion of Tc cells from B cell follicles is thought to be a major mechanism of immune evasion. New strategies are therefore needed to eradicate infected cells in follicles for a permanent cure. Using mouse infection models and human samples, we here identify a specialized group of TC cells expressing the chemokine receptor CXCR5 that can selectively enter B cell follicles and eradicate infected TFH and B cells. We demonstrate that differentiation of these cells, which we term follicular cytotoxic T (TFC) cells, requires the transcription factors Bcl6, E2A and Tcf1, whereas the transcriptional regulators Blimp1, Id3 and Id2 inhibit their development. We demonstrate that Blimp1 and E2A directly regulate Cxcr5 expression, and together with Bcl6 and Tcf1 form a transcriptional circuit that guides the TFC differentiation. The identification of a follicular subset of TC cells has far reaching implications for developing better strategies for the control of infections that target B cells and TFH cells and for the eradication of B cell derived malignancies. There is no associated input.
Project description:CD8+ T-cells inhibit virus replication in SIV-infected rhesus macaques (RM). However, it is not clear how SIV infection is controlled in germinal center during chronic SIV infection and limited information exists on the characteristics of CXCR5+ CD8 T cells during chronic SIV/HIV infection. In this study, we used functional genomics to investigate characteristic features and potential mechanisms of CXCR5+ and CXCR5- SIV specific CD8 T cells for the control of pathogenic SIV infection. Six chronically SIV infected RMs, three SIVE660 infected and three SIV mac251 infected that are positive for Mamu A01 allele were selected and SIV-specific CXCR5+ and CXCR5- CD8 T cells were sorted based on CXCR5 expression. RNA from sorted cells were extracted and microarray were performed and analysed. Principal component analysis demonstrated that overall gene expression difference between CXCR5+ and CXCR5- SIV-specific CD8 T cells. Interestingly, the CXCR5+ CD8 T cells revealed a distinct gene signature pattern when compared to CXCR5- CD8 T cells. Unlike the CXCR5- CD8 T cells, the CXCR5+ CD8 T cells expressed higher levels of genes associated with Tfh CD4 T cells such as the master transcription factor Bcl6, CD200, and CTLA4 as well as markers associated with Th2 CD4 T cells such as IL-4R (CD124), CCR4, STAT6, NFATC, and IL-10. Effector molecules typically observed in cytotoxic CD8 T cells such as granzyme A, B, and K were expressed at lower levels on CXCR5+ CD8 T cells compared to their CXCR5- counterparts. CXCR5+ CD8 T cells also expressed higher levels of molecules associated with co-stimulation/antigen presentation such as CD40, CD83, 41BBL and MAMU-DRA. The CXCR5+ CD8 also expressed higher levels of inhibitory receptors such as CD200 and SPRY2 but lower levels of other inhibitory receptors CD160 and CD244. The functional consequence of the expression of these molecules is yet to be determined. Additionally, CXCR5+ CD8 T cells expressed higher levels of the anti-apoptotic gene Bcl-2 and lower levels of the pro-apoptotic gene annexin, suggestive of their better survival potential during chronic SIV infection. Collectively, these results demonstrate that SIV specific CXCR5+ CD8 T cells possess a unique gene expression signature compared to SIV-specific CXCR5- CD8 T cells.
Project description:Lymphoid tissues are an important HIV reservoir site that persists in the face of antiretroviral therapy and natural immunity. Targeting these reservoirs by harnessing the antiviral activity of local tissue-resident memory (TRM) CD8+ T-cells is of great interest, but limited data exist on TRM-like cells within lymph nodes of people living with HIV (PLWH). Here, we studied tonsil CD8+ T-cells obtained from PLWH and uninfected controls from South Africa. We show that these cells are preferentially located outside the germinal centers (GCs), the main reservoir site for HIV, and display a low cytolytic and transcriptionally TRMlike profile distinct from blood CD8+ T-cells. In PLWH, CD8+ TRM-like cells are highly expanded and adopt a more cytolytic, activated, and exhausted phenotype not reversed by antiretroviral therapy (ART). This phenotype was enhanced in HIV-specific CD8+ T-cells from tonsils compared to matched blood suggesting a higher antigen burden in tonsils. Single-cell transcriptional and clonotype resolution showed that these HIV-specific CD8+ T-cells in the tonsils express heterogeneous signatures of T-cell activation, clonal expansion, and exhaustion ex-vivo. Interestingly, this signature was absent in a natural HIV controller, who expressed lower PD-1 and CXCR5 levels and reduced transcriptional evidence of T-cell activation, exhaustion, and cytolytic activity. These data provide important insights into lymphoid tissue-derived HIVspecific CD8+ TRM-like phenotypes in settings of HIV remission and highlight their potential for immunotherapy and targeting of the HIV reservoirs.
Project description:Lymphoid tissues are an important HIV reservoir site that persists in the face of antiretroviral therapy and natural immunity. Targeting these reservoirs by harnessing the antiviral activity of local tissue-resident memory (TRM) CD8+ T-cells is of great interest, but limited data exist on TRM-like cells within lymph nodes of people living with HIV (PLWH). Here, we studied tonsil CD8+ T-cells obtained from PLWH and uninfected controls from South Africa. We show that these cells are preferentially located outside the germinal centers (GCs), the main reservoir site for HIV, and display a low cytolytic and transcriptionally TRMlike profile distinct from blood CD8+ T-cells. In PLWH, CD8+ TRM-like cells are highly expanded and adopt a more cytolytic, activated, and exhausted phenotype not reversed by antiretroviral therapy (ART). This phenotype was enhanced in HIV-specific CD8+ T-cells from tonsils compared to matched blood suggesting a higher antigen burden in tonsils. Single-cell transcriptional and clonotype resolution showed that these HIV-specific CD8+ T-cells in the tonsils express heterogeneous signatures of T-cell activation, clonal expansion, and exhaustion ex-vivo. Interestingly, this signature was absent in a natural HIV controller, who expressed lower PD-1 and CXCR5 levels and reduced transcriptional evidence of T-cell activation, exhaustion, and cytolytic activity. These data provide important insights into lymphoid tissue-derived HIVspecific CD8+ TRM-like phenotypes in settings of HIV remission and highlight their potential for immunotherapy and targeting of the HIV reservoirs.
Project description:The vast majority of currently licensed human vaccines work on the basis of long-term protective antibody responses. Generation of long term humoral immunity is a complex process predominantly dependent on germinal centers and CD4 T cell help to B cells. Follicular helper T cells (Tfh) are the specialized CD4 T cells for B cell help. However, whether such cells develop memory in humans and can be tracked in human blood has been enigmatic. We identified a subpopulation of blood CXCR5+ PD-1+CXCR3- resting CD4 T cells that are most related to Tfh cells of lymphoid tissue by gene expression profile and phenotype. Functional analysis showed that these memory Tfh cells were specialized for helping B cells. Moreover, these cells correlate with a clinically important outcome: development of potent neutralizing antibodies against HIV in HIV+ individuals. CD4 T cells were enriched from fresh blood of 5 normal donors by magnetic beads negative selection. Following enrichment, CD14-CD16-CD19-CD8-CD4+CD45RA- cells from each donor were FACS sorted into the following 5 populations: CXCR5-, CXCR5+PD1+CXCR3-, CXCR5+PD1+CXCR3+, CXCR5+PD1-CXCR3-, and CXCR5+PD1-CXCR3+. The gene expression profile of each cell population was determined.