Expression of Foxp3 by T follicular helper cells in end-stage germinal centers
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE173227 | GEO | 2021/07/15
REPOSITORIES: GEO
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Project description:Follicular helper T (Tfh) cells access the B cell follicle to promote antibody responses, and are particularly important for germinal center (GC) reactions. However, the molecular mechanisms of how Tfh cells are physically associated with GCs are incompletely understood. Here we report that the sphingosine-1-phosphate receptor 2 (S1PR2) gene is highly expressed in a subpopulation of Tfh cells that localizes in GCs. S1PR2-deficient Tfh cells exhibited reduced accumulation in GCs due to their impaired retention. T cells deficient in both S1PR2 and CXCR5 were ineffective in supporting GC responses compared to T cells deficient only in CXCR5. These results suggest that S1PR2 and CXCR5 cooperatively regulate localization of Tfh cells in GCs to support GC responses. Venus-high Tfh, Venus-low Tfh, PD1-intermediate Th, PD1-low Th and naïve CD4+ T cells were sorted on FACSAria from immunized S1pr2V/+ mice or control mice for RNA extraction and hybridization on Affimetrix microarrays.
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Project description:Common variable immunodeficiency (CVID), characterized by recurrent infections, low serum class-switched immunoglobulin isotypes and poor antigen specific antibody responses, comprises a heterogeneous patient population in terms of clinical presentation and underlying etiology. The diagnosis is regularly associated with a severe decrease of germinal center (GC) derived B-cell populations in peripheral blood. However, data from B-cell differentiation within GC is limited. We present a multiplex approach combining histology, flow cytometry and B-cell receptor repertoire analysis of sorted GC B-cell populations allowing the modelling of distinct disturbances in GCs of three CVID patients. Our results reflect pathophysiological heterogeneity underlying the reduced circulating pool of post-GC memory B cells and plasmablasts in the three patients. In patient 1, quantitative and qualitative B-cell development in GCs is relatively normal. In patient 2, irregular shaped GCs are associated with reduced somatic hypermutation (SHM), antigen selection and class-switching, while in patient 3, high SHM, impaired antigen selection and class-switching with large single clones imply increased re-cycling of cells within the irregular shaped GCs. In lymph nodes of patients 2 and 3, only limited numbers of memory B cells and plasma cells are formed. While reduced numbers of circulating post GC B cells is a general phenomenon in CVID, the integrated approach exemplified distinct defects during GC maturation ranging from near normal morphology and function to severe disturbances with different facets of impaired maturation of memory B cells and/or plasma cells. Integrated dissection of disturbed GC B-cell maturation by histology, flowcytometry and BCR repertoire analysis reveals essential steps during memory formation.
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Project description:A range of current candidate AIDS vaccine regimens are focused on generating protective HIV neutralizing antibody responses. Many of these efforts rely on the rhesus macaque animal model. Understanding how protective antibody responses develop and how to increase their efficacy are both major knowledge gaps. Germinal centers (GC) are the engines of antibody affinity maturation. GC T follicular helper (GC Tfh) CD4 T cells are required for GCs. Studying vaccine-specific GC Tfh cells after protein immunizations has been challenging, as antigen-specific GC Tfh cells are difficult to identify by conventional intracellular cytokine staining (ICS). Cytokine production by GC Tfh cells may be intrinsically limited in comparison to other T helper effector cells, as the biological role of a GC Tfh cell is to provide help to individual B cells within the GC, rather than secreting large amounts of cytokines bathing a tissue. To test this idea, we developed a cytokine-independent method to identify antigen-specific GC Tfh cells. RNAseq was performed using TCR stimulated GC Tfh cells to identify candidate markers based on differentially expressed genes and other criteria. Validation experiments determined CD25 (IL2Ra) and OX40 to be highly upregulated activation induced markers on the surface of GC Tfh cells after stimulation. In comparison to ICS, the activation induced marker (AIM) assay identified > 10-fold more antigen-specific GC Tfh cells in HIV Env protein immunized macaques (BG505 SOSIP). Additionally, the AIM assay detected antigen-specific CXCR5+ and CXCR5- CD4 T cells in peripheral blood. Thus, AIM demonstrates that antigen-specific GC Tfh cells are intrinsically stingy producers of cytokines, which is likely an essential part of their biological function. Total RNA obtained from GC Tfh cells from 3 rhesus macaque lymph node cell samples stimulated with Staphylococcal Enterotoxin B compared with 2 unstimulated cell samples.
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