Expression and functional effects of alpha7 nicotinic receptor on human NK cells.

ZANETTI, S.; ZIBLATT; ZWIRNER, N; BOUZAT C

Mar del Plata

Congreso; Reunión Anual Conjunta Sociedad Argentina de Investigación Clínica (SAIC) y la Sociedad Argentina de Inmunología (SAI),; 2014

Expression and functional effects of alpha7 nicotinic receptor on human NK cells. The neurotransmitter Acetylcholine (ACh) is not exclusively synthesized in the nervous system. neurotransmitte.ACh synthesis also occurs in non-neuronal cells, such as immune cells. Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that are activated by ACh and respond by opening a cationic channel. nAChRs are pentameric proteins, which can be homomeric, such as a7. A7 is widely expressed in the nervous system and it is also present in non neuronal cells. In the present study, we investigated the expression of α7 in NK cells and the regulation of NK cell function by agonists and antagonists of α7 during their activation with IL-12, IL-18 andIL-15 for 48h. First, we determined the surface expression of α7 with Alexa488-conjugated α-bungarotoxin (α-Bgt), a specific antagonist of α7. of Binding of α-Bgt was detected on the surface of activated NK cells by confocal microscopy and flow cytometry, while it was slightly detected in non-activated cells. Using confocal microscopy and Fluo-3/AM, a Ca2+-sensitive fluorescent indicator, we observed a 1.5-2.5 fold increase of intracellular Ca2+ in activated NK cells when nicotine (an agonist of nAChRs) was added, indicating that α7 is functional inthese cells. Nicotine and PNU282987 (a specific agonist of α7) decreased the expression of NKG2D, an effect that was abolished by α-Bgt, but did not affect other NK cell receptors such as NKp46. Moreover, incubation with nicotine and PNU120596 (a specific allosteric modulator of α7) of NK cells previously stimulated with IL-12, IL-15 and IL-18 reduced the production of IFN-γ. Overall, our results provide evidence that function and NK cells can be negatively regulated by the activation of α7 receptor, which may contribute to tumor progression or dissemination of intracellular infections where NKG2D and IFN-γ play a critical role.