Bach2 deficiency leads to spontaneous expansion of IL-4-producing T follicular helper cells and autoimmunity
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ABSTRACT: The transcription factor Bach2 is a critical negative regulator of Tfh cell differentiation, especially IL-4 subset. Tfh cells from the mesenteric lymph nodes of WT and Bach2 CD4 conditional KO mice were collected to process the Rna-seq. Mechanistically, Bach2 may limit abnormal IL-4-produicng Tfh cell formation by repressing c-Maf, CXCR5 and IL-4.
Project description:T follicular helper (Tfh) cells are essential for germinal center B cell responses; however, the molecular mechanism underlying Tfh cell programming, in particular, the initial Tfh cell development, remains largely unknown. Here, we show that in vivo, despite enhanced non-Tfh effector functions, the deletion of transcription factor Bach2 still results in preferential Tfh cell differentiation. Mechanistically, the deletion of Bach2 leads to the induction of CXCR5 expression even before the up-regulation of Ascl2. Subsequently we identified a novel regulatory element in the murine CXCR5 locus that negatively regulates CXCR5 promoter activities in a Bach2-dependent manner. Furthermore, we find that Bach2 is also essential for CD4+ T cell memory including Tfh cell memory. These results demonstrate that Bach2 is a novel critical player in controlling Tfh cell responses.
Project description:We identified Bach2 as factor to be expressed at low levels in Tfh cells. Induced overexpression of Bach2 in the germinal center reaction results in loss of the Tfh cell population. RNA-seq of sorted antigen-specific Tfh and non-Tfh cells 18 hours after induction of Bach2 overexpression allowed the simultaneous analysis of Bach2 regulated genes and genes differentially expressed in Tfh and non-Tfh cells.
Project description:The transcription factor Bach2 is a susceptible gene for numerous autoimmune diseases including systemic lupus erythematosus (SLE). Bach2 -/- mice can develop a lupus-like autoimmune disease. However, the exact cellular and molecular mechanisms via which Bach2 protects the hosts from developing autoimmunity remains incompletely understood. Here, we report that Bach2 ablation on T cells, but not B cells, resulted in humoral autoimmunity, and this was associated with expansion of T follicular helper (Tfh) cells and abnormal germinal centers. Bach2 was down-regulated in Tfh cells and directly suppressed by the Tfh-defining transcription factor BCL6. Mechanistically, Bach2 directly suppresses the transcription of Cxcr5 and c-Maf, two key regulators of Tfh cell differentiation. Bach2-deficient Tfh cells were skewed toward the IL-4-producing subset, which induced IgG1 and IgE isotype switching of B cells. Heterozygous Bcl6 deficiency reduced the formation of germinal center and autoantibodies, and ameliorated the pathology in Bach2-deficient mice. Our findings identify Bach2 as a crucial negative regulator of Tfh cells at steady state and prove that Bach2 controls autoimmunity in part by restraining accumulation of pathogenic 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. 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: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: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 antigen-specific (LCMV-specific, SMARTA TCR transgenic) WT and Sh2d1a-/- follicular helper CD4 T cells (CXCR5high),versus non-follicular helper CD4 T cells (CXCR5low), eight days after viral infection.
Project description:Autoimmune T follicular helper (Tfh) cells have different properties from B6/J nonautoimmune tfh cells. To compare differences in Tfh cells due to ongoing SLE disease, spontaneous splenic Tfh (CD4+CXCR5+PD-1+) were cell sorted from a pre-enriched population of negatively isolated total CD4 cells by autoMACS. New zealand derived triple congenic lupus strain was compared with B6/J. RNA was immediately extracted with no culturing or treatment of cells.
Project description:CD4+ T follicular helper cells (TFH) are critical for the formation and function of B cell responses to infection or immunization, but also play an important role in autoimmunity. The factors that contribute to the differentiation of this helper cell subset are incompletely understood, although several cytokines including IL-6, IL-21 and IL-12 can promote TFH cell formation. Yet, none of these factors, nor their downstream cognate STATs, have emerged as non-redundant, essential drivers of TFH cells. This suggests a model in which multiple factors can contribute to the phenotypic characteristics of TFH cells. As type I interferons (IFNs) are often generated in immune responses, we set out to investigate if these factors are relevant to TFH cell differentiation. Type I IFNs promote Th1 responses, thus one possibility was these factors antagonized TFH-expressed genes. However, we show that type I IFNs (IFN-α/β) induced Bcl6 expression, the master regulator transcription factor for TFH cells, and CXCR5 and PD-1 (encoded by Pdcd1), key surface molecules expressed by TFH cells. In contrast, type I IFNs failed to induce IL-21, the signature cytokine for TFH cells. The induction of Bcl6 was regulated directly by STAT1, which bound to the Bcl6, Cxcr5 and Pdcd1 loci. These data suggest that type I IFNs (IFN-α/β) and STAT1 can contribute to some features of TFH cells but are inadequate in inducing complete programming of this subset. The role of STAT1 in type I interferon treated CD4+ T cells was investigated by Chip-seq of STAT1.
Project description:Differentiation and homeostasis of Foxp3 + regulatory T cells (Tregs) are tightly controlled by the interleukin-2 receptor (IL-2R) signaling, yet the mechanisms governing these processes are incompletely understood. Here we report that transcription factor Bach2 attenuates IL-2R signaling to coordinate Treg differentiation and homeostasis by directly repressed CD25 (IL-2Rα). Thus, Bach2 balances IL-2R signaling to orchestrate development and homeostasis of various Treg subsets.