Abstract
With the increase of infections due to multidrug resistant bacterial pathogens and the shortage of antimicrobial molecules with novel targets, interest in bacteriophages as a therapeutic option has regained much attraction. Before the launch of future clinical trials, in vitro studies are required to better evaluate the efficacies and potential pitfalls of such therapies. Here we studied in an ex vivo human airway epithelial cell line model the efficacy of phage and ciprofloxacin alone and in combination to treat infection by Pseudomonas aeruginosa. The Calu-3 cell line and the isogenic CFTR knock down cell line (cftr-) infected apically with P. aeruginosa strain PAO1 showed a progressive reduction in transepithelial resistance during 24 h. Administration at 6 h p.i. of single phage, phage cocktails or ciprofloxacin alone prevented epithelial layer destruction at 24 h p.i. Bacterial regrowth, due to phage resistant mutants harboring mutations in LPS synthesis genes, occurred thereafter both in vitro and ex vivo. However, co-administration of two phages combined with ciprofloxacin efficiently prevented PAO1 regrowth and maintained epithelial cell integrity at 72 p.i. The phage/ciprofloxacin treatment did not induce an inflammatory response in the tested cell lines as determined by nanoString® gene expression analysis. We conclude that combination of phage and ciprofloxacin efficiently protects wild type and cftr- epithelial cells from infection by P. aeruginosa and emergence of phage resistant mutants without inducing an inflammatory response. Hence, phage-antibiotic combination should be a safe and promising anti-Pseudomonas therapy for future clinical trials potentially including cystic fibrosis patients.
Highlights
MATERIALS AND METHODSPseudomonas aeruginosa is an opportunistic pathogen, able to cause acute infections as well as chronic infections in cystic fibrosis and immuno-compromised patients (Cohen and Prince, 2012)
We sought in this study to compare the response of epithelial cell lines to bacteriophages and antibiotics upon infection with P. aeruginosa reference strain PAO1
One alternative approach is the use of bacteriophages, since their mode of action is usually not compromised by classical antibiotic resistance mechanisms
Summary
Pseudomonas aeruginosa is an opportunistic pathogen, able to cause acute infections as well as chronic infections in cystic fibrosis and immuno-compromised patients (Cohen and Prince, 2012). We investigated the effect of phage/antibiotic treatments on polarized human airway epithelial cells infected with P. aeruginosa. An overnight culture of P. aeruginosa PAO1 was washed and resuspended in saline buffer (NaCl 0.9%, HEPES 10 mM, CaCl2 1.2 mM) to a density of 105 CFU/ml, and 10 μl of this suspension was added apically to the Transwell filter Cells were incubated for 6 h at 37◦C in 5% CO2 atmosphere, before treatment was applied: 10 μl of saline buffer containing 103 ± 101 PFUs of each phage and/or ciprofloxacin at 4 μg/ml final concentration in the apical fluid. The expression of 249 inflammatory genes was measured in uninfected and phage/antibiotic-treated PAO1-infected epithelial cells using the NanoString RNA detection kit (Geiss et al, 2008). One-way ANOVAs were used to establish the significance of differences observed in the transepithelial resistance measurements
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
