Development of anEx VivoPorcine Lung Model for Studying Growth, Virulence, and Signaling of Pseudomonas aeruginosa

Abstract

ABSTRACTResearch into chronic infection by bacterial pathogens, such asPseudomonas aeruginosa, uses variousin vitroand live host models. While these have increased our understanding of pathogen growth, virulence, and evolution, each model has certain limitations.In vitromodels cannot recapitulate the complex spatial structure of host organs, while experiments on live hosts are limited in terms of sample size and infection duration for ethical reasons; live mammal models also require specialized facilities which are costly to run. To address this, we have developed anex vivopig lung (EVPL) model for quantifyingPseudomonas aeruginosagrowth, quorum sensing (QS), virulence factor production, and tissue damage in an environment that mimics a chronically infected cystic fibrosis (CF) lung. In a first test of our model, we show thatlasRmutants, which do not respond to 3-oxo-C12-homoserine lactone (HSL)-mediated QS, exhibit reduced virulence factor production in EVPL. We also show thatlasRmutants grow as well as or better than a corresponding wild-type strain in EVPL.lasRmutants frequently and repeatedly arise during chronic CF lung infection, but the evolutionary forces governing their appearance and spread are not clear. Our data are not consistent with the hypothesis thatlasRmutants act as social “cheats” in the lung; rather, our results support the hypothesis thatlasRmutants are more adapted to the lung environment. More generally, this model will facilitate improved studies of microbial disease, especially studies of how cells of the same and different species interact in polymicrobial infections in a spatially structured environment.