Cyclic dinucleotides are important messengers for bacteria and protozoa and are well-characterized immunity alarmins for infected mammalian cells through intracellular binding to STING receptors. We sought to investigate their unknown extracellular effects by adding cyclic dinucleotides to the culture medium of freshly isolated human blood cells in vitro. Here we report that adenosine-containing cyclic dinucleotides induce the selective apoptosis of monocytes through a novel apoptotic pathway. We demonstrate that these compounds are inverse agonist ligands of A2a, a G ␣s -coupled adenosine receptor selectively expressed by monocytes. Inhibition of monocyte A2a by these ligands induces apoptosis through a mechanism independent of that of the STING receptors. The blockade of basal (adenosine-free) signaling from A2a inhibits protein kinase A (PKA) activity, thereby recruiting cytosolic p53, which opens the mitochondrial permeability transition pore and impairs mitochondrial respiration, resulting in apoptosis. A2a antagonists and inverse agonist ligands induce apoptosis of human monocytes, while A2a agonists are antiapoptotic. In vivo, we used a mock developing human hematopoietic system through NSG mice transplanted with human CD34؉ cells. Treatment with cyclic di-AMP selectively depleted A2a-expressing monocytes and their precursors via apoptosis. Thus, monocyte recognition of cyclic dinucleotides unravels a novel proapoptotic pathway: the A2a G ␣s protein-coupled receptor (GPCR)-driven tonic inhibitory signaling of mitochondrion-induced cell death. P urine and pyrimidine-based signaling is a fundamental and conserved mode of intercellular communication. In the body, mononucleotides are the major mediators of tissue protection and regeneration, for example, adenosine, which is released from damaged cells. In contrast, microorganisms use cyclic dinucleotides, such as cyclic di-AMP (c-di-AMP) and cyclic di-GMP (cdi-GMP), which are secreted by bacteria and protozoa, respectively (1, 2). As a defense mechanism, mammalian cells have evolved a means to sense cyclic dinucleotides. When infected with retroviruses (3) or carrying cytosolic DNA (4), cells assemble an endogenous 2=,3= cyclic GMP-AMP (cGAMP) dinucleotide which is recognized by the intracellular protein STING to induce type I interferon (IFN) responses (5). In this way, intracellular cyclic dinucleotides represent important alarmins in immunity.Extracellular cyclic dinucleotides are released from infected dying cells or damaged tissues and also represent important signals, but whether and how mammalian cells can detect these and respond is presently unknown. We hypothesized that human peripheral blood cells might be capable of detecting extracellular cyclic dinucleotides. We found that the extracellular 3=,5= cyclic dinucleotides c-di-AMP and cGAMP are specifically recognized by human monocytes expressing the A2a adenosine receptor and can selectively induce their apoptosis. Analysis of the role of A2a in this apoptotic response showed that it controls the s...
From several years, the anticancer effects of Vγ9 T lymphocytes make these cells good candidates for cancer immunotherapies. However, the proved efficacy of γδ Τ cell-based cancer immunotherapies in some clinical trials was minimized due to the inherent toxicity of IL-2, which is essential for the combination therapy with Phosphoantigen (PAg). Recently, we showed that IL-33, a γ chain receptor-independent cytokine, was able to induce the in vitro proliferation of PAg-activated Vγ9 T cells, which were fully functional expressing IFN-γ and TNF-α and showing in vitro anti-tumor cytotoxicity. We proposed IL-33 as an alternative to IL-2 for Vγ9 T cell-based cancer immunotherapies, and have therefore evaluated the efficacy of this cytokine in preclinical investigations. This study shows that human Vγ9 T cells are able to proliferate in a mouse model with the combination of PAg and rhIL-33, and that IL-33-expanded Vγ9 T cells can prevent tumor growth in a mouse lymphoma model.
Phosphoantigens (PAgs) activate V9V2 T lymphocytes, inducing their potent and rapid response in vitro and in vivo. However, humans and nonhuman primates that receive repeated injections of PAgs progressively lose their V9V2 T cell response to them. To elucidate the molecular mechanisms of this in vivo desensitization, we analyzed the transcriptome of circulating V9V2 T cells from macaques injected with PAg. We showed that three PAg injections induced the activation of the PPAR pathway in V9V2 T cells. Thus, we analyzed the in vitro response of V9V2 T cells stimulated with a PPAR agonist. We demonstrated that in vitro PPAR pathway activation led to the inhibition of the BrHPP-induced activation and proliferation of human V9V2 T cells. Since the PPAR pathway is involved in the antigen-selective desensitization of human V9V2 T cells, the use of PPAR inhibitors could enhance cancer immunotherapy based on V9V2 T cells.
Cancer immunotherapy has transformed the oncology landscape and shown promising therapeutic results in the clinic but it is also clearly facing multiple limitations. So far, the focus of immunotherapies has mainly been on the modulation of T-cells. Natural killer (NK) cells offer promising perspectives for immunotherapies as they directly kill tumor cells and produce pro-inflammatory cytokines to activate and recruit T-cells and other immune cells. Thus, NK cells are considered key players in the anti-tumor immune response that can make a “cold” tumor “hot”. However, in the tumor microenvironment (TME) of cancer patients, the low numbers of NK cells present and their exhaustion due to local immunosuppression often limit tumor cell killing. The development of NK based cell therapy products can overcome these limitations, either as single therapy or in combination with biologics such as e.g. NK cell engagers or monoclonal antibodies for boosting ADCC (antibody dependent cell cytotoxicity). To overcome the main hurdle of current autologous cell therapies, the EVOcells Oncology platform aims at developing a streamlined manufacturing process for iPSC-derived immune effector cells. The goal is to develop “off-the-shelf” cell therapy products for clinical use in large patient populations. We are currently establishing a multi-asset portfolio combining multiple immune effector cell types with different genetic editing strategies that serve to optimize this approach further. iPSC-derived NK cells (iNK cells) offer an attractive option for improving both therapeutic efficacy and safety of CAR cell therapies. Our robust, feeder-free production protocol produces iNK cells that can be reliably frozen with good recovery rates. We have generated multiple genetically modified iNK cells and have validated that the genetic modifications boost iNK function. At the end of the production process, iNK cells show phenotypic properties and single cell RNA sequencing profiles comparable to blood-derived NK cells. Importantly, iNK cells are fully functional with the ability to produce key pro-inflammatory cytokines and to form lytic immunological synapses leading to efficient killing of cancer cell lines. In addition to the killing of established tumor cell lines, we also evaluated the ability of iNK cells to kill primary leukemia cells ex vivo by using blood samples from B-cell chronic lymphocytic leukemia patients. In combination with a standard of care anti-CD20 antibody, iNK cells demonstrated the ability to kill primary leukemia cells via ADCC. Taken together, these promising results obtained with iNK cells show the potential of the EVOcells Oncology platform to deliver the next generation of cell therapies in oncology paving the way to develop a portfolio of iPSC-derived immune effector cells. Citation Format: Michael Esquerré, Audrey Holtzinger, Mélanie Pichery, Stefanie Pfaender, Saniye Yumlu, Mandy Richter, Delphine Betous, Oriane Bombarde, Mylène Gador, Nadja Sailer, Michael Paillasse, Loïc Ysebaert, Fabien Despas, Matthias Austen, Andreas Scheel, Markus Dangl. iPSC-derived natural killer cells as the front-runner program of the EVOcells Oncology platform: From inception to translational validation using patient samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2749.
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