Polymicrobial extracellular vesicles reduce the innate immune response of human cystic fibrosis bronchial epithelial cells

We developed a polymicrobial culture model containing four genera that represents a ‘pulmotype’ detected in ~34% of lung infections in people with CF (pwCF), and accounts for 27% of the variability in lung function. This community, comprised of Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus sanguinis, and Prevotella melaninogenica, is grown in synthetic CF media (SCFM2) under anoxic conditions that mimic the environment in mucus plugs in CF.

We have shown that Pseudomonas in monoculture communicates with primary human bronchial epithelial cells (pHBEC) by secreting bacterial extracellular vesicles (bEVs) that diffuse through mucus and deliver virulence factors, DNA, and RNA to pHBEC. We report herein that each bacterial genus in the polymicrobial community secretes bEVs containing proteins and RNAs predicted to promote the establishment of chronic infection by enhancing virulence and biofilm formation, and upregulating the stress response and pro-inflammatory pathways in pHBEC.