Early life innate immune responses to RSV in cystic fibrosis airway epithelium

Respiratory syncytial virus (RSV) infection is the major cause of severe lower respiratory tract disease in young infants. Evidence suggests that cystic fibrosis (CF) is associated with significant morbidity following RSV infection. We and others previously demonstrated that airway epithelium is the primary target of RSV infection. However, little is known about the impact of RSV infection on CF airway epithelium. To address this, we established and characterised well-differentiated primary nasal epithelial cell cultures (WD-PNECs) from recently diagnosed CF infants to study RSV cytopathogenesis in CF airway epithelium. CF WD-PNECs were successfully generated from 11 infants and characterised by light and fluorescent microscopy. CF WD-PNECs secreted thick dry apical mucous, consistent with in vivo observations. Extensive cilia coverage was also evident, although cilia beat frequencies appeared lower than those evident in WD-PNECs from healthy neonates. Quantification of goblet and ciliated cells in the CF WD-PNEC cultures were similar to those of healthy cultures. Viral growth kinetics were similar for CF WD-PNECs and healthy WD- PNECs, with peak virus titres evident at 72–96 hpi. CXCL8/IL-8 and CXCL10/IP-10 secretions were upregulated following RSV infection of CF WD-PNECs, while IL-6 secretions did not change. Interestingly, our data suggested that duoxa2 and duox2 expression post-infection were reduced in WD-PNECs from CF compared to healthy infants. Our data suggest that this model provides an exciting opportunity to elucidate the cytopathogenic, inflammatory and molecular consequences of RSV infection of airway epithelium derived from very young CF infants.