Project description:The goal of this study is to determine the impact of Tcf1 and Lef1 deficiency on T follicular helper (Tfh) cells elicited by protein immunization. We demonstrate that although phenotypic Tcf1/Lef1-deficient Tfh cells were able to develop in response to vaccination, they are functionally impaired. Mechanisc studies reveal the direct regulatory effect by Tcf1 and Lef1 on transcriptome and chromatin accessibility in vaccine-elicited Tfh cells. Analysis of chromatin accessibility in WT and Tcf1/Lef1-deficient Tfh cells eliciated by vaccination.
Project description:The goal of this study is to determine the impact of Tcf1 and Lef1 deficiency on T follicular helper (Tfh) cells elicited by protein immunization. We demonstrate that although phenotypic Tcf1/Lef1-deficient Tfh cells were able to develop in response to vaccination, they are functionally impaired. Mechanisc studies reveal the direct regulatory effect by Tcf1 and Lef1 on transcriptome and chromatin accessibility in vaccine-elicited Tfh cells.
Project description:The goal of this study is to determine the impact of Tcf1 and Lef1 deficiency on T follicular helper (Tfh) cells elicited by protein immunization. We demonstrate that although phenotypic Tcf1/Lef1-deficient Tfh cells were able to develop in response to vaccination, they are functionally impaired. Mechanisc studies reveal the direct regulatory effect by Tcf1 and Lef1 on transcriptome and chromatin accessibility in vaccine-elicited Tfh cells.
Project description:T follicular helper (Tfh) cells constitute an essential cell type in the induction of antibodies. We report that CD4 T cells lacking Foxo1 almost uniformly became CXCR5int Tfh cells following immunization. Moreover, a Foxo1 loss-of-function complemented an Icos mutation allowing the appearance of Tfh cells along with follicular, class-switched B cells and IgG isotype anti-DNA antibodies. Similarly, FOXO1 deficient Tfh differentiation displayed a substantially reduced dependence on ICOSL. Functional and molecular analyses show that FOXO1 regulates Tfh differentiation through a broad program of gene expression exemplified by positive regulation of Icos and negative regulation of Bcl6. These results demonstrate that a key step in Tfh differentiation is the ICOS-initiated activation of the PI3K-AKT pathway resulting in the inactivation of FOXO1. Performed ChIP-seq analysis to examine the role of foxo1 in the development of Tfh cells
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. Analysis of in vivo polyclonal GC Tfh vs Tfh vs Non-Tfh eight days after LCMV viral infection. Analysis of in vivo follicular helper CD4 T cells (CXCR5high GL7low), versus germinal center follicular helper CD4 T cells (CXCR5hi GL7hi), versus non-follicular helper CD4 T cells (CXCR5low) eight days after viral infection.
Project description:Follicular helper T (Tfh) are a subset of CD4+ T helper cells that provide help to germinal center B cells and mediate the development of long-lived humoral immunity. Tfh cells dysregulation is associated with several major autoimmune diseases. Although recent studies showed Tfh cells differentiation is controlled by the transcription factor Bcl6, cytokines and cell-cell signals, limited information is available on the proteome and post-translational modifications (PTM) of proteins in human Tfh cells. In this study, using TMT labeling technique, antibody-based affinity enrichment and high-resolution LC-MS/MS analysis, we investigated quantitative proteome and acetylome in human naive CD4+ T cells and in vitro induced Tfh (iTfh) cells. In total, we identified 802 up-regulated proteins and 598 down-regulated proteins at the threshold of 1.5 folds in iTfh cells compared to naive CD4+ T cells. With the aid of intensive bioinformatics, biological process, cellular compartment, molecular function, KEGG pathway and protein-protein interaction of these differentially expressed proteins were revealed. Moreover, our acetylome data showed that 22 lysine acetylated proteins are up-regulated and 26 lysine acetylated proteins are down-regulated in iTfh cells compared to the naive CD4+ T cells, among which 11 differentially acetylated lysine residues in core histone were identified, indicating proteins acetylation and epigenetic mechanism are involved in regulating Tfh cells differentiation. These data provide a significant resource for studies of Tfh differentiation and normal and perturbed Tfh cell function.
Project description:Follicular T helper cells (Tfh) provide critical help to B cells for germinal center (GC) formation. Mutations affecting SLAM-associated Protein (SAP) prevent GC formation due to defective T-B cell interactions, yet effects on Tfh cell differentiation remain unclear. We describe the in vitro differentiation of functionally-competent “Tfh-like” cells that expressed Interleukin-21, Tfh markers, and Bcl6, and rescued GC formation in SAP-deficient hosts better than other T helper (Th) cells. SAP-deficient Tfh-like cells appeared virtually indistinguishable from wildtype, yet failed to support GCs in vivo. Interestingly, both Tfh-like and in vivo-derived Tfh cells could produce effector cytokines in response to polarizing conditions. Moreover, Th1, Th2 and Th17 cells could be reprogrammed to obtain Tfh characteristics. ChIP-Seq analyses revealed positive epigenetic markings on Tbx21, Gata3 and Rorc in Tfh-like and ex vivo Tfh cells, and Bcl6 in other Th cell populations, supporting the concept of plasticity between Tfh and other Th cells. Epigenetic modifications were evaluated in ChIP-Seq studies by profiling histone H3K4 and H3K27 trimethylation marks between Th1, Th2, Th17, Tfh-like, and CXCR5+PD-1+ sorted Tfh-like in vitro generated T helper cell populations and ex vivo derived Tfh cells.