A physical linkage between cystic fibrosis airway surface dehydration and Pseudomonas aeruginosa biofilms

A vexing problem in cystic fibrosis (CF) pathogenesis has been to explain the high prevalence of Pseudomonas aeruginosa biofilms in CF airways. We speculated that airway surface liquid (ASL) hyperabsorption generates a concentrated airway mucus that interacts with P. aeruginosa to promote biofilms. To model CF vs. normal airway infections, normal (2.5% solids) and CF-like concen-trated (8% solids) mucus were prepared, placed in flat chambers, and infected with an Ϸ5 ؋ 10 3 strain PAO1 P. aeruginosa. Although bacteria grew to 10 10 cfu/ml in both mucus concentrations, mac-rocolony formation was detected only in the CF-like (8% solids) mucus. Biophysical and functional measurements revealed that concentrated mucus exhibited properties that restrict bacterial motility and small molecule diffusion, resulting in high local bac-terial densities with high autoinducer concentrations. These prop-erties also rendered secondary forms of antimicrobial defense, e.g., lactoferrin, ineffective in preventing biofilm formation in a CF-like mucus environment. These data link airway surface liquid hypera-bsorption to the high incidence of P. aeruginosa biofilms in CF via changes in the hydration-dependent physical– chemical properties of mucus and suggest that the thickened mucus gel model will be useful to develop therapies of P. aeruginosa biofilms in CF airways.

Duke Scholars

Author Michael Rubinstein Thomas Lord Department of Mechanical Engineering and Materia ...