B. pertussis suppresses proinflammatory citokines-mediated nets-induction released by epithelial cells during infection

GORGOJO, JUAN PABLO; LAMBERTI, YANINA; OVIEDO, JUAN MARCOS; RODRIGUEZ, MARÍA EUGENIA

Mar del Plata

Congreso; LXIV reunión anual de la sociedad argentina de inmunología (SAI); 2016

Sociedad Argentina de Inmunología

Recent studies demonstrated that B. pertussis (Bp) has the ability to inhibit neutrophil extracellular traps (NETs) formation in response to the proinflamatory stimulus of IL-8. However, this cytoquine is a weak inducer of NETs. Moreover, in our hands, IL-8 alone does not induce significant NETosis even at supraphysiological concentrations (1000 ng/ml). Since, Bp might be exposed to a more complex, usually stronger NETs-inducer stimulus in vivo, we here investigated the interaction of Bp with epithelial cells and its relevance in NETs production. We used the 16HBE14o- epithelial cell line derived from human bronchial epithelium, which retains differentiated epithelial morphology features and functions. We found that 16HBE14o- epithelial cells secrete IL-8, IL-6 and TNF-α in response to Bp infection, as determined by ELISA. By mean of DNA labeling with propidium iodide, antibodies against NET-associated proteins, and fluorescence microscopy we observed that conditioned medium, obtained after incubation of bacteria with 16HBE14o- cells, induced NETs release. Our results show that the NETs-inducer stimulus associated to bacterial infection of epithelial cells can be inhibited by Bp. This effect proved dependent on CyaA-mediated ROS inhibition activity as determined by blocking antibodies against this toxin. These results show that Bp is able to control this essential neutrophil bactericidal mechanism even in a complex proinflammatory environment. Together with previous results these data highlight the role of CyaA in Bp evasion of the immune response against this bacterium.