A filamentous phage triggers antiviral responses in cystic fibrosis basal airway epithelial cells

Abstract: Basal airway epithelial cells are a multipotent stem cell population which gives rise to several airway cell types. Basal cells are known to be critical to airway epithelium homeostasis and repair, and altered basal cell phenotypes have been reported in cystic fibrosis and idiopathic pulmonary fibrosis. However, very little is known about how basal cells respond to stimuli in the cystic fibrosis airway environment. Cystic fibrosis patients experience chronic infection with Pseudomonas aeruginosa and contain both high quantities of lipopolysaccharide (LPS) as well as the filamentous bacteriophage Pf produced by biofilm-state P. aeruginosa in the airway. In this study, we sought to investigate the transcriptional responses of human basal cells from both healthy controls and patients with cystic fibrosis to LPS and Pf phage. Basal cells from wildtype and cystic fibrosis donors were cultured in vitro and exposed to LPS and/or Pf phage, followed by single-cell sequencing on the 10x platform. We report that basal cells show strong antiviral responses and neutrophil chemokine production in response to Pf phage. We validate these findings in additional donors by qRT-PCR and show that Pf phage is internalized by basal cells. We also show that Pf decreases basal cell migration and proliferation. We demonstrate that Pf phage, a bacteria-infecting virus which does not replicate in mammalian cells, is taken up by basal cells and activates immune responses. Further studies are needed to determine the impact of this antiviral response to bacterial clearance.