WS14.04 Pseudomonas aeruginosa infection drives complex host responses in a cystic fibrosis-derived airway model

Objectives: This study aimed to profile the host-microbe responses underlying cystic fibrosis (CF) lung infections with Pseudomonas aeruginosa (PA).

Methods: Non-CF and CF primary epithelial cells and the BCi-NS1.1 cell lines were cultured under Air-Liquid Interface (ALI) conditions and inoculated with PA isolates collected from CF patients at the onset and after several years of infection, hence representing different levels of adaptation. Morphological changes of differentiated cells were monitored by confocal microscopy, epithelial integrity, and cytokine secretion over periods of 14 to 38 hs of infection. In addition, bacterial populations and host tissue responses were evaluated through dual-species transcriptomic sequencing (bulk RNA-seq).

Results: Depending on the adaptational level of the investigated PA isolates, the individual infection processes followed different routes. Early isolates, like environmental strains, colonize the epithelium as large colonies, reduce the epithelial integrity, and penetrate the cell layer. In contrast, well adapted isolates do not damage the epithelium and mainly exhibit single-cell distribution. We also noticed that CF airway epithelium seems to be more susceptible to bacterial penetration. RNA sequencing data document how the host human cells respond to PA colonization by a dysregulation of the calcium signaling pathway as well as an activation of signal transduction mechanisms resulting in upregulation of certain inflammatory cytokines and genes with antibacterial activity.

Conclusions: Human airway epithelium responds to colonization by PA by a complex induction of regulated gene expression. There is a coupling between the state of PA airway adaptation and the actual infection process in the ALI infection model. The CF epithelium displays intrinsic differences that might lead to a higher susceptibility to infection than that observed for normal epithelium.