Quorum Sensing Down-Regulation Counteracts the Negative Impact of Pseudomonas aeruginosa on CFTR Channel Expression, Function and Rescue in Human Airway Epithelial Cells.

Émilie Maillé,Shantelle L Lafayette,Manon Ruffin,Geoffrey Mckay,Damien Adam,Emmanuelle Brochiero,Dao Nguyen,Hatem Messaoud

doi:10.3389/fcimb.2017.00470

Abstract

The function of cystic fibrosis transmembrane conductance regulator (CFTR) channels is crucial in human airways. However unfortunately, chronic Pseudomonas aeruginosa infection has been shown to impair CFTR proteins in non-CF airway epithelial cells (AEC) and to alter the efficiency of new treatments with CFTR modulators designed to correct the basic CFTR default in AEC from cystic fibrosis (CF) patients carrying the F508del mutation. Our aim was first to compare the effect of laboratory strains, clinical isolates, engineered and natural mutants to determine the role of the LasR quorum sensing system in CFTR impairment, and second, to test the efficiency of a quorum sensing inhibitor to counteract the deleterious impact of P. aeruginosa both on wt-CFTR and on the rescue of F508del-CFTR by correctors. We first report that exoproducts from either the laboratory PAO1 strain or a clinical ≪Early≫ isolate (from an early stage of infection) altered CFTR expression, localization and function in AEC expressing wt-CFTR. Genetic inactivation of the quorum-sensing LasR in PAO1 (PAO1ΔlasR) or in a natural clinical mutant (≪Late≫ CF-adapted clinical isolate) abolished wt-CFTR impairment. PAO1 exoproducts also dampened F508del-CFTR rescue by VRT-325 or Vx-809 correctors in CF cells, whereas PAO1ΔlasR had no impact. Importantly, treatment of P. aeruginosa cultures with a quorum sensing inhibitor (HDMF) prevented the negative effect of P. aeruginosa exoproducts on wt-CFTR and preserved CFTR rescue by correctors in CF AEC. These findings indicate that LasR-interfering strategies could be of benefits to counteract the deleterious effect of P. aeruginosa in infected patients.

Highlights

Anion secretion through cystic fibrosis transmembrane conductance regulator (CFTR) channels expressed at the apical membrane of airway epithelial cells (AEC) is essential to maintain an adequate airway periciliary liquid volume necessary for effective mucociliary clearance, a key mechanism to clear inhaled pathogens from the lungs
We recently demonstrated that exoproducts from P. aeruginosa modulate wt-CFTR expression and function in AEC (Trinh et al, 2015)
Our study first showed that exoproducts from P. aeruginosa laboratory and clinical strains with functional LasR impaired both expression and function of wt-CFTR, as well as the functional rescue of F508del-CFTR by VRT-325 and Vx-809 correctors

Summary

Introduction

Anion secretion through cystic fibrosis transmembrane conductance regulator (CFTR) channels expressed at the apical membrane of airway epithelial cells (AEC) is essential to maintain an adequate airway periciliary liquid volume necessary for effective mucociliary clearance, a key mechanism to clear inhaled pathogens from the lungs. In cystic fibrosis (CF) airways, mutations in the Cftr gene lead to dysfunctional Cl− and HCO−3 secretion associated with reduced periciliary liquid volume, impaired mucociliary clearance, accumulation of viscous mucus and airway surface liquid acidification. These phenomena, in turns, favor bacterial infections (Haq et al, 2015). Most CF patients are chronically colonized by Pseudomonas aeruginosa (P. aeruginosa) This pathogen readily adapts to its environment and displays extensive genotypic and phenotypic changes over the course of chronic infection in the human lung (Folkesson et al, 2012). LasR is the primary transcriptional regulator for quorum sensing, a bacterial communication system that allows for coordinated gene expression, including genes involved in virulence factor production (Feliziani et al, 2010; Jimenez et al, 2012; Qin et al, 2012; Rutherford and Bassler, 2012)

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