title: Leptin modulates dose-dependently the metabolic and cytolytic activities of NK-92 cells.
abstract: Leptin, a hormone-cytokine produced primarily in the adipose tissue, has pleiotropic effects on many biological systems and in several cell types, including immune cells. Hyperleptinemia is associated with immune dysfunction and carcinogenesis. Natural killer (NK) cells are critical mediators of anti-tumor immunity, and leptin receptor deficiency in mice leads to impaired NK function. It was thus decided to explore the in vitro effects of leptin on human NK cell function. NK-92 cells were cultured during 48 h with different leptin concentrations [absence, 10 (physiological), 100 (obesity), or 200 ng/ml (pharmacology)]. Their metabolic activity was assessed using the resazurin test. NK-92 cell cytotoxicity and intracellular IFN-γ production were analyzed by flow cytometry. NK-92 cell mRNA and protein expression levels of cytotoxic effectors were determined by RT-qPCR and Western blot. In our conditions, leptin exerted a dose-dependent stimulatory effect on NK-92 cell metabolic activity. In addition, high leptin concentrations enhanced NK-92 cell cytotoxicity against K562-EGFP and MDA-MB-231-EGFP target cells and inversely reduced cytotoxicity against the MCF-7-EGFP target. At 100 ng/ml, leptin up-regulated both NK cell granzyme B and TRAIL protein expressions and concomitantly down-regulated perforin expression without affecting Fas-L expression. In response to PMA/ionomycin stimulation, the proportion of IFN-γ expressing NK-92 cells increased with 100 and 200 ng/ml of leptin. In conclusion, leptin concentration, at obesity level, variably increased NK-92 cell metabolic activity and modulated NK cell cytotoxicity according to the target cells. The underlying mechanisms are partly due to an up-regulation of TRAIL and IFN-γ expression and a down-regulation of perforin.
authors.affiliation: Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine, Equipe ECREIN, CLARA, CRNH Auvergne; INRA, UMR 1019, UNH, CRNH Auvergne, Clermont-Ferrand, France. bruno.lamas@ext.udamail.fr
authors.forename: Bruno
authors.initials: B
authors.lastname: Lamas
authors.forename: Nicolas
authors.initials: N
authors.lastname: Goncalves-Mendes
authors.forename: Rachida
authors.initials: R
authors.lastname: Nachat-Kappes
authors.forename: Adrien
authors.initials: A
authors.lastname: Rossary
authors.forename: Florence
authors.initials: F
authors.lastname: Caldefie-Chezet
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Vasson
authors.forename: Marie-Chantal
authors.initials: MC
authors.lastname: Farges
mesh_terms: D015153:Blotting, Western; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007202:Indicators and Reagents; D007371:Interferon-gamma / Q000378:metabolism; D059425:Interferon-gamma Release Tests; D015759:Ionomycin / Q000494:pharmacology; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D020738:Leptin / Q000494:pharmacology*; D061986:MCF-7 Cells; D010078:Oxazines; D054353:Perforin / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D054411:Receptors, Leptin / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation; D014966:Xanthenes
chemical_list: D007202:Indicators and Reagents; C515448:LEPR protein, human; D020738:Leptin; D010078:Oxazines; D012333:RNA, Messenger; D054411:Receptors, Leptin; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014966:Xanthenes; C485184:enhanced green fluorescent protein; D054353:Perforin; D049452:Green Fluorescent Proteins; C005843:resazurin; D015759:Ionomycin; D007371:Interferon-gamma; D013755:Tetradecanoylphorbol Acetate