AbstractsMedical & Health Science

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. The underlying pathophysiological mechanisms of increased morbidity in cystic fibrosis patients with chronic Pseudomonas aeruginosa infection associated with secondary respiratory viral infections are not well understood. Here we studied antiviral Interferon-β (IFN-β) and inflammatory Interleukin-8 (IL-8) responses following a major group rhinovirus (HRV16) infection with and without prestimulation with diffusible products of Pseudomonas aeruginosa (difPA). CF (delF508 CFTR homo- and heterozygous) and non-CF primary bronchial epithelial cells were obtained from patients or healthy donors during lung transplantation to compare the antiviral and inflammatory responses for these studies. Cells were grown under submerged conditions until confluent, and either infected with HRV16 at TCID50 of 104.37/ml or 103.85/ml or stimulated with difPA to mimic exposure to virulence factors secreted by Pseudomonas aeruginosa (P. aeruginosa) biofilm in vivo. In some experiments, cells were prestimulated with difPA followed by infection with HRV16 to understand the dual effect of P. aeruginosa and HRV16 infection in CF lower airway cells. Supernatants and lysates were collected from in vitro experiments and IFN- and IL-8 responses were quantified by ELISA (protein) and qPCR (mRNA). Our study demonstrates no significant difference in antiviral (IFN-β) response in CF bronchial epithelial cells compared to healthy bronchial epithelial cells following infection with HRV16, not even in presence of difPA mediated prestimulation. Therefore, no immunosuppression of IFN- response was observed due to prestimulation with difPA in the HRV16 infected CF and non-CF bronchial epithelial cells. However, IL-8 (a major neutrophil chemoattractant) was up-regulated in CF bronchial epithelial cell more than non-CF bronchial epithelial cells due to prestimulation with difPA followed by infection with HRV16. Furthermore, the HRV16 load was higher in CF bronchial epithelial cells compared to healthy bronchial epithelial cells in the presence or absence of difPA mediated stimulation. Taken together, this study suggests up-regulation of the interferon-β response at similar levels following HRV16 infection in CF and non-CF airway epithelial cells. However, the interferon-β response is very possibly inadequate for high HRV16 load in CF airway epithelial cells, results in deficiency of viral clearance. Finally, our data suggest P. aeruginosa and HRV16 infection mediated synergistic up-regulation of IL-8 response in CF bronchial epithelial cells more than non-CF bronchial epithelial cells. Whether IFN-β stimulation in CF bronchial epithelial cells leads to efficient viral clearance and thus to reduce IL-8 level needs further investigation. La fibrose kystique (FK, ou mucoviscidose) est une maladie à transmission autosomique récessive liée à des mutations du gène CFTR (sigle pour cystic fibrosis transmembrane…