RNA FROM PSEUDOMONAS AERUGINOSA ATTENUATES NEUTROPHIL FUNCTIONS

JOSE RAMÓN PITTALUGA; FEDERICO BIRNBERG- WEISS; JOSELYN CASTRO; LUIS CASTILLO MONTAÑEZ; SERAFINO, AGUSTINA; MARTIRE GRECO, DAIANA; GABRIELA CRISTINA FERNÁNDEZ; VERONICA INÉS LANDONI

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Congreso; Reunion conjunta anual 2022; 2022

Pseudomonas aeruginosa (PAE) is a well-known opportunist microorganism capable of cause multiples diseases. When immune cells arrive to the site of infection, they are exposed to RNA from bacteria. We have previously documented that RNA from Escherichia coli (RNAECO) or RNA from Klebsiella pneumoniae (RNAKPN) were able to activate neutrophils (PMN), whereas RNA from PAE (RNAPAE) failed to induce PMN activation.The aim of this work was to further characterize the effects of RNAPAE on PMN response. PMN were isolated from healthy donor and incubated with purified RNA from bacteria (1μg/mL) or live bacteria (MOI 1:1) for 30 minutes. Activation of PMN was measured by flow cytometry (CD11b mean intensity), PMN migration was determined using a Boyden chamber and IL-8 was determined with ELISA KIT.Results showed that RNAPAE failed to induce IL-8 secretion or chemotactic activity compare to RNAEco and RNAKPN (p≤0.05). Surprisingly, activation of PMN observed with RNAECO or RNAKPN was diminished when RNAPAE was present (p≤0.05), suggesting that RNAPAE modulates negatively PMN activation by others prokaryotic RNA.We next wondered if RNAPAE was able to modulate PMN response to bacteria. Therefore, when live PAE were used as stimulus, activation, chemotaxis and bactericidal ability of PMN was significantly reduced when RNAPAE was present (p≤0.05). None of the RNA were able to decrease the PMN response against ECO and KPN.In conclusion, these results revealed that RNAPAE diminishes PMN response to PAE. Further studies will allow to determine if RNAPAE constitutes a mechanism to attenuate PMN response favoring PAE survival in an infectious focus.