Establishment and characterization of a new Pseudomonas aeruginosa infection model using 2D airway organoids and dual RNA sequencing

Pseudomonas aeruginosa is a Gram-negative bacterium that is notorious for infections in the airway of cystic fibrosis (CF) subjects. Often, these infections become chronic, leading to higher morbidity and mortality rates. Bacterial quorum sensing (QS) coordinates the expression of virulence factors and the formation of biofilms at a population level. QS has become the focus of attention for development of alternatives to antimicrobials targeting P. aeruginosa infections. However, a better understanding of the bacteria-host interaction, and the role of QS in infection, is required. In this study, we set up a new P. aeruginosa infection model, using 2D airway organoids derived from healthy and CF individuals. Using dual RNA-sequencing, we dissected their interaction, focusing on the role of QS. As expected, P. aeruginosa induced epithelial inflammation. However, QS signaling did not affect the epithelial airway cells. The epithelium influenced several infection-related processes of P. aeruginosa, including metabolic changes, induction of type 3 and type 6 secretion systems (T3SS and T6SS), and increased expression of antibiotic resistance genes, including mexXY efflux pump and several porins. Interestingly, the epithelium influenced the regulation by QS of the type 2 (T2SS) and T6SS. Finally, we compared our model with in vivo P. aeruginosa transcriptomic datasets, from samples directly isolated from the airways of CF subjects. This shows that our model recapitulates important aspects of in vivo infection, like enhanced denitrification, betaine/choline metabolism, increased antibiotic resistance, as well as an overall decrease of motility-related genes. This relevant infection model is interesting for future investigations, helping to reduce the burden of P. aeruginosa infections in CF.