Biology subjects

Fourcade, G.

Publications and source records attributed to Fourcade, G..

4 recordsLinked to original sources

bioRxiv2024

IL-1β Signaling Modulates T Follicular Helper and Regulatory Cells in Human Lymphoid Tissues

BackgroundDysregulation of the T follicular helper (Tfh) and T follicular regulatory (Tfr) homeostasis in the germinal center (GC) can result in antibody-mediated autoimmunity. While interleukin-1{beta} (IL-1{beta}) has been shown to be an important modulator of the GC response in animal models via the expression of IL-1 agonist (IL-1R1) and antagonist (IL-1R2) receptors on follicular T cells, such regulation has not yet been studied in humans. MethodsWe investigated Tfh and Tfr phenotypes in human secondary lymphoid organs -- namely tonsils, spleens, and mesenteric lymph nodes -- using flow cytometry, single-cell transcriptomics, and in vitro cell culture. We also benchmarked our findings with a cohort of patients with autoimmune and inflammatory diseases. ResultsWe found that Tfh and Tfr cells exhibit organ-specific phenotypes related to their activation status and IL-1 receptor expression. An excess of IL-1R1 over IL-1R2 was linked to the emergence of a unique activated Tfr subset that combines features of both Treg and GC-Tfh cells. Single-cell transcriptomics and in vitro studies showed that IL-1{beta} signaling through IL-1R1 promotes follicular T-cell activation. Inhibiting IL-1{beta} resulted in upregulation of IL-1R1 expression, showing a fine-tuned regulation. In autoimmune patients, high IL-1{beta} and circulating Tfr levels correlated with higher autoantibody levels, linking inflammation, IL-1{beta} signaling, and the Tfr/Tfh balance. ConclusionsOur study underscores the pivotal role of IL-1{beta} in follicular T-cell activation, contributing to pathological antibody production in humans. Targeting IL-1{beta} signaling in Tfh and Tfr cells could offer new treatment strategies for antibody-mediated autoimmune diseases.

immunology↗

bioRxiv2024

Expression of IL-1R2 by Tfr prevents their IL-1-dependent proliferation and the exacerbation of allergy

The antibody response is regulated by follicular T helper (Tfh) and regulatory (Tfr) cells that control the germinal center (GC) reaction. Recent research has shown that Tfh/Tfr have a unique pattern of IL-1 receptor expression. We investigated the mechanisms by which this IL-1 axis in GCs could regulate the allergic response. To study this, we generated CD4creIL-1R1lox mice, specifically lacking IL-1R1 expression in T cells and FoxP3creIL-1R2lox mice, specifically lacking IL-1R2 expression in Tfr cells. The conditional knockout mice were compared to their respective control mice in a model of ovalbumin (OVA) sensitization and anaphylaxis, and a phenotypic and functional characterization of humoral and cellular responses was performed. While CD4creIL-1R1lox mice showed little phenotypic changes, FoxP3creIL-1R2lox mice were highly susceptible to allergic anaphylaxis and generated an increase in IgE responses that promoted basophil degranulation. Additionally, FoxP3creIL-1R2lox mice displayed significantly reduced OVA-specific IgG responses, limiting their ability to control allergy via the inhibitory IgG receptor Fc{gamma}RIIb. Although FoxP3creIL-1R2lox mice showed an overall increase in splenic T and B cell numbers, they were unable to efficiently generate proliferating GC B cells. Upon ex vivo IL-1{beta} and/or OVA re-stimulation, we observed a striking IL-1R1-dependent activation and proliferation of Tfr cells in FoxP3creIL-1R2lox splenocytes, that was neither observed in Tregs nor in Tfh. At the same time, B cell proliferation upon re-stimulation was suppressed. These findings suggest that IL-1R2 expression on Tfr cells prevents allergy by limiting excessive Tfr activation and suppressing the IgG/IgE ratio.

immunology↗

bioRxiv2023

Tissue-resident uterine regulatory T cells support fetal growth

Regulatory T cells (Tregs) are known to contribute to successful allogeneic pregnancy by promoting maternal-fetal tolerance. Here, phenotypic studies and parabionts identified a population of uterine tissue-resident Tregs (uTregs) with trophic functions in the non-pregnant mouse endometrium. Phenotypically, uTregs are CD25-/lo and they present characteristic phenotypic attributes of tissue-resident memory T cells with effector functions. Transcriptionally, uTregs are distinguishable from other peripheral or tissue-resident Tregs by their expression of genes related to extracellular matrix remodeling and vasculogenesis, and they express a polyclonal T cell receptor (TCR) repertoire. Pregnancy triggers the expansion of uTregs, which remain CD25-/lo, retain their polyclonal TCR repertoire, and increase the expression of genes involved in regulation of hypoxia and vasculogenesis. Functionally, we show that uTregs support the proliferation of primary uterine microvascular endothelial cells in vitro and that a specific depletion of uTregs in pregnant mice leads to fetal intra-uterine growth retardation (IUGR). Thus, a previously unidentified population of CD25-/lo uTregs promotes uterine tissue remodeling before and during pregnancy, and contributes to fetal growth.

immunology↗

bioRxiv2023

Interleukin-1 regulates follicular T cells during the germinal center reaction

Antibody production by plasma cells and generation of long-term memory B-cells are positively regulated by Tfh cells and negatively regulated by Tfr cells in germinal centers. However, the precise role of Tfr cells in controlling antibody production is still unclear. We have previously shown that Tfh and Tfr cells both express IL-1R1, while only Tfr cells express the IL-1R2 decoy and IL-1Ra antagonist receptors. To study the role of these receptors in the regulation of the B cell response by Tfh and/or Tfr cells, we generated mice with knockout of IL-1 receptors in Tfh and/or Tfr cells and measured antibody production and cell activation upon immunization. We showed that IL-1{beta} concentration is increased in the draining lymph node after immunization. Antigen-specific antibody levels and cell activation phenotypes indicated that IL-1{beta} can activate both Tfh and Tfr cells through IL-1R1 stimulation. Surprisingly, IL-1R2 and IL-1Ra expression on Tfr cells does not block IL-1 activation of Tfh cells, but rather prevents IL-1/IL-1R1-mediated early activation of Tfr cells. IL-1Rs similarly regulate antibody response against autoantigens and its related pathophysiology in an experimental lupus model. Altogether, these results show that IL-1R1 inhibitory receptors expressed by Tfr cells prevent their own activation and suppressive function, thus licensing IL-1-mediated activation of Tfh cells after immunization. One Sentence SummaryFunctional knockout of IL-1 agonist (R1) and antagonist (R2 and Ra) receptors reveals that IL-1-R2 and -Ra on Tfr cells prevent their own early activation to license the expansion and activation of Tfh cells after immunization.

immunology↗