Project description:ICOS is a T cell costimulatory receptor critical for Tfh cell generation and function. However, the role of ICOS in Tfr cell differentiation remains unclear. Using Foxp3-Cre-mediated ICOS knockout (ICOS FC) mice, we show that ICOS deficiency in Treg-lineage cells drastically reduces the number of Tfr cells during GC reactions but has a minimal impact on conventional Treg cells. Single-cell transcriptome analysis of Foxp3+ cells at an early stage of the GC reaction suggests that ICOS normally inhibits Klf2 expression to promote follicular features including Bcl6 upregulation. Further, ICOS costimulation promotes nuclear localization of NFAT2, a known driver of CXCR5 expression. Notably, ICOS FC mice had an unaltered overall GC B cell output but showed signs of expanded autoreactive B cells along with elevated autoantibody titers. Thus, our study demonstrates that ICOS costimulation is critical for Tfr cell differentiation and highlights the importance of Tfr cells in maintaining humoral immune tolerance during GC reactions.
Project description:Abatacept is a recombinant CTLA-4 moleculed fused to a mutated human IgG molecule, which is clinically used in rheumatoid arthritis by inhibiting CD28-costimulation. This study aimed to inverstigate the ability of abatacept -mediated costimulation blockade to induce antigen-specific tolerance during primary immune responses. This is important as some studies have suggested that costimulation blockade can lead to CD4+ T cell anergy which could be beneficial for early therapy of autoimmune diseases such as rheumatoid arthritis. In addition we also investigated the effect that abatacept has on CD11c+ antigen presenting cells. This is important as costimulation blocakde can affect the biderectional interaction between CD4+ T cells and CD11c+ cells influencing the immunological outcome. We used microarrays to identify if abatacept treatment leads to antigen specific anergy using transgenic animals and models of priming and oral tolerance that established a synchronised monoclonal response. In addition this magnified the effect on the CD11c+ antigen presenting cells. This study included 5 experimental groups. DO11.10 RAG2-/- mice have CD4+ T cells specific for the ovalbumin (OVA) peptide OVA323-339. These mice were immunised with CFA/OVA s.c. (primed group) or tolerised by feeding with OVA (50mg/kg) in the drinking water. CD4+ cells were isolated 10 days post immunisation from draining lymph nodes (LNs) of unimmunised (pooled LNs and Spleen), orally tolerised (mesenteric LNs), primed (axillary LNs), primed treated with control IgG (axillary LNs) and primed treated with abatacept (axillary LNs). For CD11c+ cells cells were isolated by pooled secondary lymphoid organs (LNs and spleen).
Project description:Aanlysis of human resting CD4+T cells and cells activated by two different methods: CD4+ T cells unstimulated (be susceptible but not support to HIV-1) and stimulated either by CD3/CD28 costimulation (reversed susceptibility and resisted to HIV-1) or by PHA/IL-2 for six days (be susceptible and support to HIV-1) to investigate potential mechanism of reversing susceptible to HIV-1. We measured gene expression in resting human CD4+T cells and cells activated by two methods for six days which could induce different effects to HIV-1. Three independent experiments were performed at each treatments using different donors for each experiment.
Project description:Comparatative gene expression analysis for wild type and NFAT2-/- CD4 T cell subsets including follicular helper CD4+ T (TFH) cells, activated CD4+ T cells, and naive CD4+ T cells isolated from the spleen.
Project description:Engagement of the ICOS receptor represents a key event in a process that culminates in Bcl6 expression and acquisition of the TFH and TFR phenotype. To better understand the essentials of ICOS-mediated signaling pathway, we profiled the changes in gene expression elicited after co-ligation of ICOS and CD3 compared with CD3 ligation alone. Naïve CD4+ T-cells were purified from single cell suspensions of B6 spleen and stimulated with anti-CD3 and anti-CD28 for 2d followed by resting overnight before 20 min of incubation with anti-CD3 and/or anti-ICOS and cross-linking with goat anti-hamster Ab for 8h. RNA was prepared, amplified, labeled and hybridized to Mouse Gene 1.0 ST Array (Affymetrix), in quadruplicates for anti-CD3 ligation and duplicates for anti-CD3/ anti-ICOS co-ligation.
