39 research outputs found
Caractérisation phénotypique et fonctionnelle d une sous population lymphocytaire Tab associée aux muqueuses (Les cellules MAIT (Mucosal Associated Invariant T))
No full textPARIS5-BU Méd.Cochin (751142101) / SudocSudocFranceF
Abstract 3751: Allogeneic EGFRvIII chimeric antigen receptor T cells for treatment of glioblastoma
No full textAbstract
Glioblastoma multiforme (GBM) is a highly aggressive form of brain tumors with a 5-year survival rate of less than 10%. Standard-of-care combining radiation therapy with temozolomide only yields a median survival of 14.6 months and more effective therapeutic options to extend patient lives are urgently needed. EGFR variant III (EGFRvIII) is a tumor specific mutant of EGFR found in 25-30% of GBM but not expressed in healthy tissues. EGFRvIII is formed by an in-frame deletion of exons 2-7 of the wild-type EGFR which leads to removal of 267 amino acids in the extracellular domain of the receptor. The truncated receptor loses its ability to bind ligands but acquires constitutive kinase activity. The lack of normal tissue expression makes EGFRvIII an ideal target for developing CAR T therapy. Most CAR T therapies in clinical development use the patients’ own T cells for CAR T manufacturing. Our approach is to develop an “off-the-shelf” CAR-T treatment for GBM using healthy donor T cells with the TCR (T-cell receptor) disrupted to prevent graft-versus-host disease. This allogeneic approach could circumvent challenges faced by some patients due to limited availability and quality of their own T cells and rapid progress of their diseases, and has the potential to reduce the high cost associated with autologous CART therapy. Using phage panning and hybridoma approaches, we generated a series of humanized and fully human EGFRvIII antibodies with a wide range of affinities. Recombinant EGFRvIII protein binding by Biacore and FACS assays using EGFRvIII and EGFR wild-type expressing cells demonstrated that these antibodies are highly specific for EGFRvIII. The antibodies were converted to ScFvs and cloned into a CAR vector. Subsequently, EGFRvIII CARs were transduced into primary human T cells for functional studies. We developed a series of assays to evaluate CAR expression, degranulation activity and target dependent cytotoxicity. Our goal is to select CAR candidate that is safe, persistent and has potent target dependent cytotoxicity.
Citation Format: Oi Kwan Wong, Mathilde Dusseaux, Jing-Tyan Ma, Melinda Au, Sophie Leduc, Joyce Chou, Jessica M. Yu, Marjorie Bateman, Thomas Pertel, Kevin C. Lindquist, Julianne Smith, Barbra Sasu, Shu-Hui Liu. Allogeneic EGFRvIII chimeric antigen receptor T cells for treatment of glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3751. doi:10.1158/1538-7445.AM2017-3751</jats:p
A new Ser472Asn (Cab2a+) polymorphism localized within the αIIb “thigh” domain is involved in neonatal thrombocytopenia
No full textAlphaIIbbeta3 integrin: new allelic variants in Glanzmann thrombasthenia, effects on ITGA2B and ITGB3 mRNA splicing, expression, and structure-function.: New mutations in Glanzmann patients and carriers
No full textInternational audienceGlanzmann thrombasthenia (GT) is an autosomal recessive inherited bleeding disorder characterized by an impaired platelet aggregation due to defects in integrin alphaIIbbeta3 (ITGA2B, ITGB3), a fibrinogen receptor. Mutations from 24 GT patients and two carriers of various origins, Caucasian, North-African and Asian were characterized. Promoter and exon sequences of alphaIIb and beta3 genes were amplified and directly sequenced. Among 29 identified mutations, 17 new allelic variants resulting from nonsense, missense and deletion/insertion mutations were described. RNA alterations were evaluated by using Web servers. The alphaIIb p.S926L, p.V903F, and beta3 p.C38Y, p.M118R, p.G221D substitutions prevented complex expression at the surface of COS-7 cells by altering the alphaIIb or the beta3 subunit structure. As shown by free energy analyses applied on the resolved structure of alphaIIbbeta3 and structural modeling of the mutant, the p.K253M substitution of beta3 helped to define a key role of the K253 in the interaction of the alphaIIb beta-propeller and the beta3 beta-I domains. finally, the alphaIIb p.Q595H substitution allowed cell surface expression of the complex but its corresponding c.2800G>T mutation is predicted to alter normal RNA splicing. In conclusion, our study yielded the discovery of 17 new GT allelic variants, revealed the key role of K253 of alphaIIb for the alphaIIbbeta3 complex formation and provides an additional example of an apparently missense mutation causing a splicing defect
Anti-PD-1 therapy triggers Tfh cell–dependent IL-4 release to boost CD8 T cell responses in tumor-draining lymph nodes
No full textInternational audienceAnti-PD-1 therapy targets intratumoral CD8+ T cells to promote clinical responses in cancer patients. Recent evidence suggests an additional activity in the periphery, but the underlying mechanism is unclear. Here, we show that anti-PD-1 mAb enhances CD8+ T cell responses in tumor-draining lymph nodes by stimulating cytokine production in follicular helper T cells (Tfh). In two different models, anti-PD-1 mAb increased the activation and proliferation of tumor-specific T cells in lymph nodes. Surprisingly, anti-PD-1 mAb did not primarily target CD8+ T cells but instead stimulated IL-4 production by Tfh cells, the major population bound by anti-PD-1 mAb. Blocking IL-4 or inhibiting the Tfh master transcription factor BCL6 abrogated anti-PD-1 mAb activity in lymph nodes while injection of IL-4 complexes was sufficient to recapitulate anti-PD-1 mAb activity. A similar mechanism was observed in a vaccine model. Finally, nivolumab also boosted human Tfh cells in humanized mice. We propose that Tfh cells and IL-4 play a key role in the peripheral activity of anti-PD-1 mAb
Long Peptide Vaccination Can Lead to Lethality through CD4+ T Cell-Mediated Cytokine Storm
No full textAbstract
The optimization of anticancer therapeutic vaccines can lead to better efficacy but also to stronger adverse effects. In a mouse model of antitumor vaccination using a long peptide (LP), which included MHC class I- and II-restricted male (H-Y) epitopes, we observed unexpected mortality. Mice with an increased frequency of anti–H-Y CD4 T cells were primed with LP+CpG and boosted 10 d later. Within hours of boost, they displayed shock-like signs with high mortality. Serum cytokine levels were high. TNF-α secreted by the CD4 T cells was identified as the key effector molecule. Priming with a short peptide (SP), which included the MHC class II-restricted epitope, was a more efficient primer than LP, but did not lead to mortality when used as boost. The high mortality induced by LP compared with SP was probably related to its specific ability to be presented by B cells. Finally, targeting the LP sequence to dendritic cells allowed tumor protection without side effects. Our data: 1) confirm that the immune system can be very dangerous; 2) caution against the use of systemic activation of high-frequency Ag-specific T cells as induced by high doses of LP; and 3) underline the benefit of targeting Ag to dendritic cells.</jats:p
Human MAIT cells are xenobiotic-resistant, tissue-targeted, CD161hi IL-17–secreting T cells
No full textAbstract
Mucosal-associated invariant T (MAIT) cells are very abundant in humans and have antimicrobial specificity, but their functions remain unclear. MAIT cells are CD161hiIL-18Rα+ and either CD4−CD8− (DN) or CD8αβint T cells. We now show that they display an effector-memory phenotype (CD45RA−CD45RO+CD95hiCD62Llo), and their chemokine receptor expression pattern (CCR9intCCR7−CCR5hiCXCR6hiCCR6hi) indicates preferential homing to tissues and particularly the intestine and the liver. MAIT cells can represent up to 45% of the liver lymphocytes. They produce interferon-γ and Granzyme-B as well as high levels of interleukin-17 after phorbol myristate acetate + ionomycin stimulation. Most MAIT cells are noncycling cells (< 1% are Ki-67+) and express the multidrug resistance transporter (ABCB1). As expected from this phenotype, MAIT cells are more resistant to chemotherapy than other T-cell populations. These features might also allow MAIT cells to resist the xenobiotics potentially secreted by the gut bacteria. We also show that this population does not appear to have antiviral specificity and that CD8 MAIT cells include almost all the ABCB1+CD161hi CD8 T cells. Together with their already known abundance and antimicrobial specificity, the gut-liver homing characteristics, high expression of ABCB1, and ability to secrete interleukin-17 probably participate in the antibacterial properties of MAIT cells.</jats:p
Anti-microbial activity of Mucosal Associated Invariant T cells
No full textInternational audienceMucosal associated invariant T (MAIT) lymphocytes are characterized by two evolutionarily conserved features: an invariant TCRα chain and restriction by the MHC-related protein, MR1. Here we show that MAIT cells are activated by cells infected with different strains of bacteria and yeasts, but not viruses, both in human and mouse. This activation requires cognate interaction between the invariant T cell receptor (TCR) and MR1, which can present a bacteria-derived ligand. In humans, we observe a striking diminution of MAIT cell blood-numbers in patients with bacterial infections such as tuberculosis. In mouse, MAIT cells protect against infections by Mycobacterium and Escherichia coli. Thus, MAIT cells are evolutionarily conserved innate-like lymphocytes that sense and help fight off microbial infections
