Patient-Specific Coculture of S. aureus and P. aeruginosa Enhances Epithelial Barrier Disruption and Virulence in CRS.

BACKGROUND: Chronic rhinosinusitis (CRS) is a chronic inflammatory disease that is associated with polymicrobial infections, often involving S. aureus and P. aeruginosa. It is unclear whether the polymicrobial context plays a role in exacerbating epithelial damage, inflammation, and resistance to therapy. METHODS: S. aureus and P. aeruginosa (n = 3 each) biofilms were established in a Transwell system, followed by the extraction of P. aeruginosa conditioned media and application to an air-liquid interface (ALI) model of human nasal epithelial cells (HNECs). Transepithelial electrical resistance (TEER) and FITC dextran paracellular permeability tests evaluated the epithelial integrity. Colony-forming unit (CFU) counting, protease activity assay, and pyocyanin and pyoverdine quantification were used to test the proliferation and production of virulence factors of the bacteria. RESULTS: Cocultures of P. aeruginosa and S. aureus isolated from the same patient reduced HNEC TEER values, had an earlier onset of HNEC barrier disruption, and increased paracellular permeability compared to monocultures of P. aeruginosa. P. aeruginosa proliferation was enhanced, and protease activity increased significantly. The production of pyoverdine increased significantly in the same patient cocultures, while the pyocyanin levels remained unchanged. CONCLUSIONS: These results indicate a role of within-host evolution in shaping P. aeruginosa-mediated virulence in the context of polymicrobial biofilms. This supports the need to develop strategies directed at disrupting interspecies synergies that culminate in the formation of polymicrobial biofilms associated with CRS for the purpose of improving disease management and therapeutic efficacy.