Project description:FOXP3+ T follicular regulatory cells (Tfrs) control germinal center (GC) responses by steering antibody formation away from self-reactivity and toward microbe/vaccine recognition. As originally described, murine Tfr cells descend exclusively from thymically-derived, self-antigen recognizing, T regulatory cells (Tregs), but newer animal models suggest vaccine-recognizing T follicular helper (Tfh) cells can assume regulatory roles as GCs mature. To test the hypothesis that the human Tfr pool is heterogenous in function and provenance, we used paired TCRVA and TCRVB sequencing to distinguish tonsillar Tfr cells clonally related to the natural Tregs (nTfr) from those induced from Tfh cells (iTfr). Through in silico predictions and in vitro tonsillar organoid lineage tracking, we identified a Tfh to iTfr developmental trajectory that passed through a distinct CD25hiBLIMP1+FOXP3- transitional stage. The genes and proteins that iTfr and nTfr cells express differentially were utilized as handles to precisely pinpoint the in situ locations of cells from each subset via multi-plex microscopy and to establish divergent functional adaptations. In total, we characterize human iTfr cells as a GC-resident CD38+ Tfr subset that descend from Tfh lineage cells to gain suppressive qualities while retaining their capacity for GC B-cell help.
Project description:The mechanisms by which FOXP3+ T follicular regulatory (Tfr) cells simultaneously steer antibody formation toward microbe or vaccine recognition and away from self-reactivity remain incompletely understood. To explore underappreciated heterogeneity in human Tfr cell development, function, and localization, we used paired TCRVA/TCRVB sequencing to distinguish tonsillar Tfr cells that are clonally related to natural regulatory T cells (nTfr) from those likely induced from T follicular helper (Tfh) cells (iTfr). The proteins iTfr and nTfr cells differentially expressed were used to pinpoint their in situ locations via multiplex microscopy and establish their divergent functional roles. In silico analyses and in vitro tonsil organoid tracking models corroborated the existence of separate Treg-to-nTfr and Tfh-to-iTfr developmental trajectories. Our results identify human iTfr cells as a distinct CD38+, germinal center-resident, Tfh-descended subset that gains suppressive function while retaining the capacity to help B cells, whereas CD38- nTfr cells are elite suppressors primarily localized in follicular mantles. Interventions differentially targeting specific Tfr cell subsets may provide therapeutic opportunities to boost immunity or more precisely treat autoimmune diseases.
Project description:CD4 T cell help is critical for both the generation and maintenance of germinal centers, and T follicular helper (TFH) cells are the CD4 T cell subset required for this process. SAP (SH2D1A) expression in CD4 T cells is essential for germinal center development. However, SAP-deficient mice have only a moderate defect in TFH differentiation as defined by common TFH surface markers. CXCR5+ TFH cells are found within the germinal center as well as along the boundary regions of T/B cell zones. Here we show that germinal center associated T cells (GC TFH) can be identified by their co-expression of CXCR5 and the GL7 epitope, allowing for phenotypic and functional analysis of TFH and GC TFH populations. Here we show GC TFH are a functionally discrete subset of further polarized TFH cells, with enhanced B cell help capacity and a specialized ability to produce IL-4 in a TH2-independent manner. Strikingly, SAP-deficient mice have an absence of the GC TFH subset and SAP- TFH are defective in IL-4 and IL-21 production. We further demonstrate that SLAM (Slamf1, CD150), a surface receptor that utilizes SAP signaling, is specifically required for IL-4 production by GC TFH. GC TFH cells require IL-4 and IL-21 production for optimal help to B cells. These data illustrate complexities of SAP-dependent SLAM family receptor signaling, revealing a prominent role for SLAM receptor ligation in IL-4 production by germinal center CD4 T cells but not in TFH and GC TFH differentiation. This SuperSeries is composed of the following subset Series: GSE21379: Expression Data from WT and Sh2d1a-/- in vivo follicular helper CD4 T cells (TFH) versus non follicular helper CD4 T cells (non-TFH) GSE21380: Expression Data from in vivo Tfh vs GC Tfh vs non-Tfh Refer to individual Series
Project description:Despite interest in T follicular helper (TFH) cell development and function, differences between TFH cells resident in germinal centers (GCs) and phenotypically similar, non-resident TFH cells are unclear. Both TFH subsets share the Bcl6+FoxP3−CXCR5hiPD-1hi phenotype but we show that only GC resident TFH cells express S1pr2 and lose CD90 expression. Whereas immunization elicits CD90neg/lo GCTFH and CD90hi GCTFH-like cells similarly, these TFH subsets have distinct properties. CD90neg/lo GCTFH cells require MHCII+ B cells to develop and once formed, do not proliferate. CD90hi GCTFH-like cells are generated in the absence of B cells and remain mitotically active. The Tcrβ repertoires of both TFH types are initially shared but with time, Tcrβ usage in CD90hi GCTFH-like cells substantially diverges by DC-driven proliferation. Transcriptome analysis shows CD90neg/lo GCTFH to be specialized for vesicle transport and exocytosis while gene expression in CD90hi GCTFH-like cells is linked to cell activation, proliferation and migration.
Project description:The Germinal center is a dynamic microenvironment wherein B cells expressing high affinity antibody variants produced by hypermutation are selected for clonal expansion by limiting numbers of T follicular helper cells. Although a great deal is known about the mechanisms that control B cell selection in the germinal center, far less is understood about the clonal behavior of the T follicular helper cells that regulate this process. Here we report on the dynamic behavior of clones of T follicular helper cells during the germinal center reaction. We find that like germinal center B cells, T follicular helper cells undergo antigen dependent selection during the germinal center reaction resulting in differential proliferative expansion and contraction. Increasing the amount of antigen presented in the germinal center leads to increased T follicular cell division. Competition between T follicular helper cell clones is mediated by T cell receptor affinity for peptide-MHC ligand. Higher affinity T cells expanding preferentially in the germinal center show increased expression of genes downstream of the T cell receptor, genes required for metabolic reprogramming, cell division and cytokine production. These dynamic changes lead to dramatic remodeling of the functional T follicular cell repertoire during the germinal center reaction.
Project description:Purpose: To compare the transcriptomes of IL-21-expressing, IL-21 and IL-4-expressing, and IL-4 expressing follicular helper T (Tfh) cells and Th2 cells in the spleen at 8 days following helminth infection Methods: Cell sorting of the populations was done for CD4+B220-CD44hiCXCR5hiPD-1hi cells of the various types, followed by mRNA purification.
Project description:Neonatal T follicular helper cells are lodged in a pre-T follicular helper stage favoring innate over adaptive germinal center responses
Project description:Follicular T helper (T FH ) cells have emerged as a critical limiting factor for controlling the magnitude of neonatal germinal center (GC) reactions and primary vaccine antibody responses. We compared the functional attributes of neonatal and adult T FH cells at the transcriptomic level and demonstrate that the T FH cell program is well initiated in neonates although the T FH gene-expression pattern (i.e. CXCR5, IL-21, Bcl6, TBK1, STAT4, Ascl2 and c-maf) is largely underrepresented as compared to adult T FH cells. Importantly, we identified a dominant T H2 - bias of neonatal T FH cells, with preferential differentiation toward short-lived pre-T FH effector cells. Remarkably, adjuvantation with CpG-ODNs redirect neonatal pre-T FH cells toward committed GC-T FH cells, as illustrated by increased expression of T FH signature genes and reduced expression of T H2 -related genes.
Project description:CD4 T cell help is critical for both the generation and maintenance of germinal centers, and T follicular helper (TFH) cells are the CD4 T cell subset required for this process. SAP (SH2D1A) expression in CD4 T cells is essential for germinal center development. However, SAP-deficient mice have only a moderate defect in TFH differentiation as defined by common TFH surface markers. CXCR5+ TFH cells are found within the germinal center as well as along the boundary regions of T/B cell zones. Here we show that germinal center associated T cells (GC TFH) can be identified by their co-expression of CXCR5 and the GL7 epitope, allowing for phenotypic and functional analysis of TFH and GC TFH populations. Here we show GC TFH are a functionally discrete subset of further polarized TFH cells, with enhanced B cell help capacity and a specialized ability to produce IL-4 in a TH2-independent manner. Strikingly, SAP-deficient mice have an absence of the GC TFH subset and SAP- TFH are defective in IL-4 and IL-21 production. We further demonstrate that SLAM (Slamf1, CD150), a surface receptor that utilizes SAP signaling, is specifically required for IL-4 production by GC TFH. GC TFH cells require IL-4 and IL-21 production for optimal help to B cells. These data illustrate complexities of SAP-dependent SLAM family receptor signaling, revealing a prominent role for SLAM receptor ligation in IL-4 production by germinal center CD4 T cells but not in TFH and GC TFH differentiation. This SuperSeries is composed of the SubSeries listed below.