Polymicrobial Extracellular Vesicles Reduce the Innate Immune Response of Human Cystic Fibrosis Bronchial Epithelial...

Chronic antibiotic-resistant cystic fibrosis (CF) lung infections are the leading cause of death in adults with CF. Despite advances in highly effective modulator therapies, microbial communities persist in the CF lung. The pathogenesis of CF airway infections can be exacerbated by pathogens such as Pseudomonas aeruginosa, which 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. However, most CF lung infections are polymicrobial in nature, and therefore, the contribution of polymicrobial bEVs remains to be determined. By using a polymicrobial culture model representing a 'pulmotype' detected in ∼34% of lung infections in people with CF (pwCF), comprised of P. aeruginosa, Staphylococcus aureus, Streptococcus sanguinis and Prevotella melaninogenica grown in synthetic sputum medium under anoxia, we report that each bacterial genus in the polymicrobial community secretes bEVs containing proteins and RNAs predicted to promote the establishment of chronic infection by reducing Elexacaftor/Tezacaftor/Ivacaftor (ETI) stimulated CF pHBEC CFTR Cl^- secretion, enhancing virulence and biofilm formation, and upregulating the stress response and pro-inflammatory pathways in pHBEC. This response is most pronounced in CF pHBEC. ETI, a highly effective modulator therapy, did not ameliorate the response of CF pHBEC or return it to WT levels. These studies provide insight into why ETI does not eliminate polymicrobial lung infections and a hyperinflammatory lung environment in pwCF.