An epoxide hydrolase secreted by Pseudomonas aeruginosa decreases mucociliary transport and hinders bacterial clearance from the lung

The opportunistic pathogen Pseudomonas aeruginosa colonizes the lungs of susceptible individuals by deploying virulence factors targeting host defenses. The secreted CFTR inhibitory factor (Cif) dysregulates the endocytic recycling of CFTR and thus reduces CFTR abundance in host epithelial membranes. We have postulated that the decrease in ion secretion mediated by Cif would slow mucociliary transport and decrease bacterial clearance from the lungs. To test this hypothesis, we explored the effects of Cif in cultured epithelia and in the lungs of mice. We developed a strategy to interpret the "hurricane-like" motions observed in reconstituted cultures and identified a Cif-mediated decrease in the velocity of mucus transport in vitro. Presence of Cif also increased the number of bacteria recovered at two time points in an acute mouse model of pneumonia generated by P. aeruginosa. Furthermore, recent work has demonstrated an inverse correlation between the airway concentrations of Cif and 15-epi lipoxin A₄, a pro-resolving lipid mediator important in host defense and the resolution of pathogen-initiated inflammation. Here, we observe elevated levels of 15-epi lipoxin A₄ in the lungs of mice infected with a strain of P. aeruginosa that expresses only an inactive form of cif, as compared to those mice infected with wild type P. aeruginosa. Together these data support Cif's inclusion on the list of virulence factors that assist P. aeruginosa in colonizing and damaging the airways of compromised patients. Further, this study establishes techniques that enable our groups to explore the underlying mechanisms of Cif's effects during respiratory infection.

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