RT Journal Article SR Electronic T1 Static mucus impairs bacterial clearance and allows chronic infection with Pseudomonas aeruginosa in the cystic fibrosis rat JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 2101032 DO 10.1183/13993003.01032-2021 VO 60 IS 3 A1 Alexander G. Henderson A1 Joy M. Davis A1 Johnathan D. Keith A1 Morgan E. Green A1 Ashley M. Oden A1 Steven M. Rowe A1 Susan E. Birket YR 2022 UL http://erj.ersjournals.com/content/60/3/2101032.abstract AB Cystic fibrosis airway disease is characterised by chronic Pseudomonas aeruginosa infection. Successful eradication strategies have been hampered by a poor understanding of the mechanisms underlying conversion to chronicity. The cystic fibrosis transmembrane conductance receptor (CFTR)-knockout (KO) rat harbours a progressive defect in mucociliary transport and viscosity. KO rats were infected before and after the appearance of the mucus defect, using a clinical mucoid-isolate of P. aeruginosa embedded in agarose beads. Young KO rats that were exposed to bacteria before the development of mucociliary transport defects resolved the infection and subsequent tissue damage. However, older KO rats that were infected in the presence of hyperviscous and static mucus were unable to eradicate bacteria, but instead had bacterial persistence through 28 days post-infection that was accompanied by airway mucus occlusion and lingering inflammation. Normal rats responded to infection with increased mucociliary transport to supernormal rates, which reduced the severity of a second bacterial exposure. We conclude that the aberrant mucus present in the CF airway permits persistence of P. aeruginosa in the lung.This study identifies the airway mucus response to Pseudomonas aeruginosa infection, which protects the normal airway against reinfection. The failure of this response in the cystic fibrosis lung leads to chronic infection and mucus occlusion. https://bit.ly/3nDiZCj