HUMAN NEUTROPHILS RESPONSES TO RESPIRATORY SYNCYTIAL VIRUS STIMULATION

MAIUMI SHIROMIZU C; KEITELMAN I; SALINAS M; MIGLIO RODRÍGUEZ M; FUENTES F; BAUMEISTER E; PONTORIERO A; RUSSO M; GEFFNER J; JANCIC C1; BUENO C; SABBIONE F; TREVANI A

Tucumán

Congreso; LXVII Reunión Anual de la Sociedad Argentina de Inmunología; 2019

Sociedad Argentina de Inmunología

Respiratory Syncytial Virus (RSV) infections represent the leading cause of bronchiolitis ininfants and young children worldwide and are responsible for almost 200000 deaths annually.Neutrophils constitute the predominant cellular infiltrate in the airways of infants with RSVbronchiolitis.Previous studies indicated that RSV induces Neutrophil Extracellular Traps(NETs). The aim of this study was to further investigate the response of highly purified humanneutrophils to RSV. In agreement with previous studies, we determined by immunostaining andconfocal microscopy that purified RSV induces NETosis (n=4). By quantification of DNA inculture supernatants, we detected that neutrophils produce NETs in a wide range of multiplicityof infections (n=4). However, we did not detect significant differences in LDH activity in culturesupernatants at distinct MOIs evaluated (n=6). These findings suggest that only a smallproportion of neutrophils undergoes lytic NETosis, something which was also observed by timelapselive microscopy with NucSpot 488, a cell-permeable DNA-dye (n: 1). In this livemicroscopy preliminary assay, we observed the appearance of extracellular vesicles in culturesupernatants, which progressively increased by 4 h p.s. Thus, we isolated these neutrophilderived-EVs (EV) and evaluated their impact on human monocytes isolated by adherence. RSVinducedEV (produced by 106 neutrophils) promoted monocyte IL-6 release in contrast to EVproduced by unstimulated neutrophils (868±139 vs 232±84 pg/ml; p