WS10.5 Pseudomonas aeruginosa adaptation as a potential risk factor to the progression of cystic fibrosis airway disease in mice and humans

Objectives: CF is characterized by loss of pulmonary function and tissue injury. As the disease progresses, P. aeruginosa adapts to the host and dramatically modifies its phenotype; however, it is still unclear if and how bacterial adaptation influences pathogenesis and disease development. Methods: Initially-acquired and CF-adapted P. aeruginosa clonal variants were challenged in C57Bl/6 and CF ko mice after their inclusion in agar beads. Mice were evaluated for bacterial count, lung histopathology, markers of inflammation and tissue damage. Patho-adaptive traits of P. aeruginosa isolated from CF patients airways were correlated with clinical scores. Results: Different to P. aeruginosa initially-acquired strains, CF-adapted variants caused long-term chronic infection in mice by shaping the immune response and activating pathways relevant to tissue damage and remodelling. At an advanced stage of a P. aeruginosa infection, murine airways displayed hallmarks of remodelling and fibrosis, including epithelial hyperplasia and structure degeneration, goblet cell metaplasia, collagen deposition, elastin degradation and several markers of tissue damage. In mice, these pathologic traits are only partially dependent on the CFTR genetic background. In CF patients, we observed correlation between P. aeruginosa patho-adaptive traits and inflammation, remodelling processes and lung functions suggesting exploitable disease markers. Conclusion: We conclude that bacterial adaptation may be a potential risk factor in the progression of airway disease and a critical success determinant for reproducing the human disease in mice. Supported by Italian CF Research Foundation.