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 cell

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

Human V 9V 2 T Cells Specifically Recognize and Kill Acute Myeloid Leukemic Blasts

International audienceVγ9Vδ2 T cells are attractive candidates for antileukemic activity. The analysis of Vγ9Vδ2 T cells in newly diagnosed acute myeloid leukemia (AML) patients revealed that their absolute cell numbers were normal in the blood as well as in the bone marrow but showed a striking imbalance in the differentiation subsets, with preponderance of the effector memory population. This unusual phenotype was restored after removal of leukemic cells in patients, which reached complete remission after chemotherapy, suggesting that leukemic cells might be involved in the alteration of γδ T cell development in AML. Accordingly, coculture between AML cells and Vγ9Vδ2 T cells induced selection of effector cells. In accordance with their effector memory status, in vitro proliferation of Vγ9Vδ2 T cells was reduced compared with normal controls. Nevertheless, Vγ9Vδ2 T cells efficiently killed autologous AML blasts via the perforin/granzyme pathway. The ligands for DNAM-1 were expressed by AML cells. We showed that killing of AML blasts was TCR and DNAM-1 dependent. Using a xenotransplantation murine model, we showed that Vγ9Vδ2 T cells homed to the bone marrow in close proximity of engrafted leukemic cells and enhanced survival. These data demonstrate that Vγ9Vδ2 T cells are endowed with the ability to interact with and eradicate AML blasts both in vitro and in a mouse model. Collectively, our data revealed that Vγ9Vδ2 T cells have a potent antileukemic activity provided that optimal activation is achieved, such as with synthetic TCR agonists. This study enhances the interest of these cells for therapeutic purposes such as AML treatment

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

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Bromohydrin pyrophosphate enhances antibody-dependent cell-mediated cytotoxicity induced by therapeutic antibodies

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