Optimisation de l'activité anti-tumorale des lymphocytes T gamma9delta 2 humains

Si tous les vertébrés possèdent des lymphocytes T gamma delta, seuls les primates ont une sous-population sanguine exprimant un récepteur de type TCR Vgamma9Vdelta2. Cette dernière réagit à des phosphoantigènes non-peptidiques d'origine bactérienne et tumorale, déclenchant ainsi son activité anti-infectieuse et anti-cancéreuse. Cette thèse traite de l'optimisation de son potentiel thérapeutique anti-cancéreux. Ces lymphocytes cytotoxiques capturent des fragments membranaires de leurs cellules cibles et sécrètent leurs granules cytolytiques, à travers leur synapse immunologique. L'étude par vidéo-microscopie de l'activité moléculaire à la synapse des lymphocytes T gamma delta révèle la simultanéité de ces deux processus. Ainsi, le renforcement de l'attachement des lymphocytes T gamma delta à leurs cibles par la combinaison de phosphoantigène et d'anticorps thérapeutiques permet d'optimiser leur efficacité anti-tumorale. Cette thèse présente donc les bases moléculaires d'une nouvelle approche thérapeutique anti-cancéreuse.Although all vertebrates possess gamma delta T lymphocytes, only primates have a blood-borne gamma delta T cell subset expressing a TCR Vgamma9Vdelta2 receptor. This population reacts to bacterial and tumoral non-peptidic phosphoantigens, triggering its anti-infectious and anti-cancer activity. This thesis deals with the optimization of the therapeutic anti-cancer activity of TCR Vgamma9Vdelta2 gamma delta T lymphocytes. These cytotoxic effectors capture membrane fragments of target cells and release cytolytic granules through their immunological synapse. The timelapse video-microscopy study of the molecular activity at the gamma delta T lymphocytes synapse shows both processes simultaneously. So, the strengthening of the gamma delta T lymphocytes synapses to their target through a combination of phosphoantigen and therapeutic antibody strongly optimizes their anti-tumor efficacy. This thesis presents the molecular basis for a new anti-cancer therapeutic approach

CpG-ODN-induced sustained expression of BTLA mediating selective inhibition of human B cells.

BTLA (B- and T-lymphocyte attenuator) is a prominent co-receptor that is structurally and functionally related to CTLA-4 and PD-1. In T cells, BTLA inhibits TCR-mediated activation. In B cells, roles and functions of BTLA are still poorly understood and have never been studied in the context of B cells activated by CpG via TLR9. In this study, we evaluated the expression of BTLA depending on activation and differentiation of human B cell subsets in peripheral blood and lymph nodes. Stimulation with CpG upregulated BTLA, but not its ligand: herpes virus entry mediator (HVEM), on B cells in vitro and sustained its expression in vivo in melanoma patients after vaccination. Upon ligation with HVEM, BTLA inhibited CpG-mediated B cell functions (proliferation, cytokine production, and upregulation of co-stimulatory molecules), which was reversed by blocking BTLA/HVEM interactions. Interestingly, chemokine secretion (IL-8 and MIP1β) was not affected by BTLA/HVEM ligation, suggesting that BTLA-mediated inhibition is selective for some but not all B cell functions. We conclude that BTLA is an important immune checkpoint for B cells, as similarly known for T cells

CpG-ODN-induced sustained expression of BTLA mediating selective inhibition of human B cells

BTLA (B- and T-lymphocyte attenuator) is a prominent co-receptor that is structurally and functionally related to CTLA-4 and PD-1. In T cells, BTLA inhibits TCR-mediated activation. In B cells, roles and functions of BTLA are still poorly understood and have never been studied in the context of B cells activated by CpG via TLR9. In this study, we evaluated the expression of BTLA depending on activation and differentiation of human B cell subsets in peripheral blood and lymph nodes. Stimulation with CpG upregulated BTLA, but not its ligand: herpes virus entry mediator (HVEM), on B cells in vitro and sustained its expression in vivo in melanoma patients after vaccination. Upon ligation with HVEM, BTLA inhibited CpG-mediated B cell functions (proliferation, cytokine production, and upregulation of co-stimulatory molecules), which was reversed by blocking BTLA/HVEM interactions. Interestingly, chemokine secretion (IL-8 and MIP1β) was not affected by BTLA/HVEM ligation, suggesting that BTLA-mediated inhibition is selective for some but not all B cell functions. We conclude that BTLA is an important immune checkpoint for B cells, as similarly known for T cell

Dual Face of Vγ9Vδ2-T Cells in Tumor Immunology: Anti- versus Pro-Tumoral Activities

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Molecular determinants of target cell recognition by human γδ T Cells

Copyright: © 2018 Simões, Di Lorenzo and Silva-Santos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.The unique capabilities of gamma-delta (γδ) T cells to recognize cells under stressed conditions, particularly infected or transformed cells, and killing them or regulating the immune response against them, paved the way to the development of promising therapeutic strategies for cancer and infectious diseases. From a mechanistic standpoint, numerous studies have unveiled a remarkable flexibility of γδ T cells in employing their T cell receptor and/or NK cell receptors for target cell recognition, even if the relevant ligands often remain uncertain. Here, we review the accumulated knowledge on the diverse mechanisms of target cell recognition by γδ T cells, focusing on human γδ T cells, to provide an integrated perspective of their therapeutic potential in cancer and infectious diseases.We acknowledge funding from Fundação para a Ciência e a Tecnologia (PTDC/DTP-PIC/4931/2014 to BS-S; and PD/BD/105880/2014 to BL). This publication was sponsored by LISBOA-01-0145-FEDER-007391, project cofunded by FEDER, through POR Lisboa 2020—Programa Operacional Regional de Lisboa, PORTUGAL 2020, and Fundação para a Ciência e a Tecnologia.info:eu-repo/semantics/publishedVersio

γδ T cell responses: How many ligands will it take till we know?

γδ T cells constitute a sizeable and non-redundant fraction of the total T cell pool in all jawed vertebrates, but in contrast to conventional αβ T cells they are not restricted by classical MHC molecules. Progress in our understanding of the role of γδ T cells in the immune system has been hampered, and is being hampered, by the considerable lack of knowledge regarding the antigens γδ T cells respond to. The past few years have seen a wealth of data regarding the TCR repertoires of distinct γδ T cell populations and a growing list of confirmed and proposed molecules that are recognised by γδ T cells in different species. Yet, the physiological contexts underlying the often restricted TCR usage and the chemical diversity of γδ T cell ligands remain largely unclear, and only few structural studies have confirmed direct ligand recognition by the TCR. We here review the latest progress in the identification and validation of putative γδ T cell ligands and discuss the implications of such findings for γδ T cell responses in health and disease

Optimisation de l'activité anti-tumorale des lymphocytes T gamma9delta 2 humains

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

PD-1 is a novel regulator of human B-cell activation

International audienceThe outcome of the adaptive immune response is determined by the integration of both positive and negative signals, respectively, induced upon the triggering of co-signaling receptors. One of them, programmed cell death 1 (PDCD1/PD-1) has largely been shown to be involved in the negative regulation of T-cell activation. However, PD-1 is also expressed on human B cells, and its role(s) in the process of human B-cell activation remains uncertain thus far. In this study, we describe the expression of PD-1 on the major human B-cells subsets isolated from peripheral blood and lymph nodes. We showed that PD-1 was expressed on naive B cells, was differentially expressed on peripheral IgM memory as compared with memory B cells and was lost on germinal center B cells. Expression of PD-1 ligands (PD-Ls) was induced by TLR9 activation. Finally, we showed that PD-1 was recruited to the B-cell receptor upon triggering. We determined that during TLR9 activation, blockade of PD-1/PD-Ls pathways indeed increased B-cell activation, proliferation and the production of inflammatory cytokines. Altogether, our results show, that, as reported in T cells, PD-1/PD-Ls complexes acted as inhibitors of the B-cell activation cascade and highlight the importance of devising future therapies able to modulate lymphocyte activation through the targeting of the PD-1/PD-Ls pathways

BTN3A molecules considerably improve Vγ9Vδ2T cells-based immunotherapy in acute myeloid leukemia.

International audienceGiven their recognized ability to kill acute myeloid leukemia (AML) blasts both in vitro and in vivo, Vγ9Vδ2 T cells are of growing interest in the design of new strategies of immunotherapy. We show that the Butyrophilin3A (BTN3A, CD277) subfamily is a critical determinant of Vγ9Vδ2 TCR-mediated recognition of human primary AML blasts ex vivo. Moreover, anti-BTN3A 20.1 agonist monoclonal antibodies (mAbs) can trigger BTN3A on AML blasts leading to further enhanced Vγ9Vδ2 T cell-mediated killing, but this mAb had no enhancing effect upon NK cell-mediated killing. We show that monocytic differentiation of primary AML blasts accounts for their AminoBisphosphonate (N-BP)-mediated sensitization to Vγ9Vδ2 T cells. In addition, anti-BTN3A 20.1 mAbs could specifically sensitize resistant blasts to Vγ9Vδ2 T cells lysis and overcome the poor effect of N-BP treatment on those blasts. We confirmed the enhancement of Vγ9Vδ2 T cells activity by anti-BTN3A 20.1 mAb using a human AML xenotransplantation mouse model. We showed that anti-BTN3A 20.1 mAb combined with Vγ9Vδ2 T cells immunotherapy could increase animal survival and decrease the leukemic burden in blood and bone marrow. These findings could be of great interest in the design of new immunotherapeutic strategies for treating AML

Emerging Concepts for the Treatment of Hematological Malignancies with Therapeutic Monoclonal Antibodies

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