Virulence factors delivered through outer membrane vesicles shape the outcome of B. pertussis-macrophage interaction

ALVARES HAYES, JIMENA; BLANCÁ, BRUNO; RODRIGUEZ, MARIA EUGENIA; VALDEZ, HUGO

Encuentro Virtual

Congreso; Reunión De Sociedades De Biociencias 2020. LXVIII Reunión Anual Sociedad Argentina de Inmunología (SAI); 2020

Sociedad Argentina de Inmunología

The outer membrane vesicles (OMVs) are bi-layer structures naturally shed by Gram-negative bacteria that usually contain bacterial virulence factors. In previous studies we found that the OMVs of Bordetella pertussis (Bp), the etiological agent of whopping cough, might influence the outcome of Bp interaction with human MΦ. In this study we tried to dissect the bacterial factors involved in this process. As first approach we determined the proteome of spontaneously released OMVs. By means of LC-MS/MS we identified a total of 350 proteins belonging to a wide range of cellular processes. Importantly, most of the Bp virulence factors were found present in these OMVs. Among them, the main bacterial adhesin, FHA, and the two main toxins, CyaA and PT. In agreement with the presence of FHA, electron and fluorescence microscopy showed that OMVs attached to and are internalized by MΦ. As determined by flow cytometry, OMVs internalized by MΦ induced a significant decrease in the surface expression of CR3, an effect attributable to CyaA according to recently published studies. CR3 is the main Bp docking molecule on MΦ. These results explain the observed decrease of MΦ Bp uptake in the presence of OMVs. We previously demonstrated that CyaA and PT are involved in the modulation of bactericidal MΦ response. In this study we observed a similar effect on MΦ treated with OMVs prior infection, as determined by RT-PCR (p