Résumés disponibles (92) :

DEVULDER Justine (UMR8204-U1019 éq. 13 - Catherine DUEZ)
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@mail :  catherine.duez@pasteur-lille.fr      tél. :  0320877105


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Titre de la communication :
Impaired activation of Natural Killer cells from severe asthmatics by pathogen-like molecules
Auteurs (et leurs adresses) de la communication :
Justine DEVULDER1, Valérie Ledroit1, Philippe Marquillies1, Cécile Chenivesse1,2, Stéphanie Fry2, Anne Tsicopoulos1,2, Catherine Duez1 1Center for Infection and Immunity of Lille, UMR8204, U1019, Institut Pasteur de Lille, France 2CHRU Lille, France
Résumé de la communication :
Severe or therapy resistant asthma is increasingly recognized as a major unmet need. Severe asthmatics suffer from frequent exacerbations mainly caused by viruses. Natural Killer (NK) cells are innate lymphocytes capable of lysing virus-infected cells, and regulating the immune response through cytokine production or interaction with other immune cells. Their role in asthma and its exacerbations is suggested by very few studies. Our hypothesis is that NK cells from severe asthmatics may present a dysfunction in their response to microbial agents. Our objective was to evaluate the effect of pathogens or molecules mimicking pathogens on NK cell function.
Peripheral Blood Mononuclear Cells (PBMC) from healthy subjects or severe asthmatics were stimulated for 24 hours with microbes or molecules mimicking microbes : interleukin (IL)-12 plus IL-15 (as positive control stimulating NK cells), polyIC (agonist for Toll-like receptor (TLR) 3), CpG (agonist for TLR9), R848 (agonist for TLR7/8), FSL1 (agonist for TLR2/6), hemagglutinin A of influenza (HA, ligand for NKp46 expressed by NK cells) and human rhinovirus (HRV)2b. We analyzed NK cell activation, cytotoxicity and cytokine expression by flow cytometry. The concentration of several cytokines was measured in PBMC supernatant by LuminexTM.
We observed no difference in the number of NK cells between severe asthmatic patients and healthy subjects. We showed that stimulation of PBMC with PolyIC, CpG, R848 and HRV2b increased the expression of CD69 and CD107 on NK cell surface, suggesting NK cell activation and degranulation. However, the expression of CD107 and CD69 was lower in NK cells from severe asthmatics, suggesting a defect in NK cell function. The stimulation with IL-12 plus IL-15 mainly activates NK cells, and induces increased IFN-γ expression in NK cells. The expression of IFN-γ was lower in NK cells from severe asthmatics compared with NK cells from healthy subjects, which is another argument in favor of intrinsic dysfunction of NK cells from severe asthmatic patients. The concentration of IFN-γ measured in culture supernatant in response to IL-12 plus IL-15 or R848 paralleled the intracellular staining, even if other cells among PBMC may produce IFN-γ. Finally the concentration of IL-6, a cytokine potentially involved in asthma severity, was higher in culture supernatants from severe asthmatics compared with controls, whatever the stimulation. The role of NK cells in the production of IL-6 remains to be investigated.
Therefore, we showed that NK cells from severe asthmatics are less cytotoxic than NK cells from healthy subjects, suggesting a defect in NK cell function. The rest of the project will allow us to determine if this defect comes from an intrinsic default of NK cells or from a dysfunction in their interaction with other immune cells.

DEVULDER Justine (UMR8204-U1019 éq. 13 - Catherine DUEZ)