Pseudomonas aeruginosa pyocyanin inactivates lung epithelial vaculoar ATPase-dependent cystic fibrosis transmembrane conductance regulator expression and localization

Abstract

SummaryPseudomonas aeruginosa ( PA ) is a major pathogen causing morbidity and ultimately mortality in patients afflicted with cystic fibrosis (CF) lung disease. One important virulence factor, pyocyanin (PCN), is a blue, redox-active compound that is secreted in such copious amounts by PA in the CF lungs that it determines the colour of expectorated sputum. In this study, we discovered that physiological concentrations of PCN inactivate the airway epithelial vacuolar ATPase, resulting in reduced expression and trafficking of the cystic fibrosis transmembrane conductance regulator in cultured lung and primary nasal epithelial cells. Our study supports the notion that PCN contributes significantly to the pathogenesis of CF and other bronchiectasis patients infected by PA .

Airway epithelial control of Pseudomonas aeruginosa infection in cystic fibrosis

“…In this regard, experimental results that do not show a much higher degree of interaction of P. aeruginosa with cells expressing WT-CFTR in comparison to those expressing only mutant CFTR are inconsistent with the processes that occur within the CF lung. To wit, results showing that WT-CFTR is a receptor for P. aeruginosa that mediates effective innate immunity and that this receptor is not functional in CF [9,10] are the ones most consistent with clinical and experimental observations. One curious additional observation about this interaction has also been reported: the mucoid strains of P. aeruginosa responsible for chronic infection lose the bacterial ligand for CFTR [8,11,12], indicating that the P. aeruginosa-CFTR direct interaction is likely to be primarily of relevance to the early stages of infection, whereas in the later stages of infection other properties of the bacterium and the CF host conspire to allow for maintenance of the chronic infectious state.…”

“…In transgenic CFTR-knockout mice, NF-κB nuclear translocation occurs much later in the airway epithelial cells [28], probably contributing more to the harmful inflammation that ensues in this environment instead of the protective inflammation that occurs when functional CFTR is present. Overall, this scenario wherein WT-CFTR binding of P. aeruginosa leads to protection and failure of this interaction in CF leads to infection is supported by data obtained in numerous in vitro and, importantly, in υivo, studies demonstrating CFTR-dependent responses to P. aeruginosa in a variety of lung epithelial cell lines and in transgenic animals [8][9][10][11][12][27][28][29]31,36]. Thus, it seems that CFTR facilitates bacterial clearance and modulates innate immunity towards P. aeruginosa in lung epithelial cells by being the linchpin needed for coordinating multiple host responses involved in resisting infection and maintaining tissue homeostasis in the long run.…”

Redox-independent Activation of NF-κB by Pseudomonas aeruginosa Pyocyanin in a Cystic Fibrosis Airway Epithelial Cell Line

“…PYO-deficient P. aeruginosa elicits less mortality in P. aeruginosa-mediated burn-sepsis model in mice, and PYO appears to be important for persistence of P. aeruginosa in lungs of CF patients (3,4,11). PYO has a multitude of effects on the physiology of epithelial cells, including inhibition or alteration of antioxidant enzymes (12,13), ciliary function (14), cellular metabolism, and organelle H ϩ v-ATPase (2,15). A key aspect of PYO pathology may result from its ability to trigger inflammation leading to the influx of neutrophils to the P. aeruginosa-infected region; PYO stimulates ICAM-1 and IL8 production on its own and also synergizes with IL1␤ and TNF␣ in stimulating IL8 production (16 -18).…”

“…Pseudomonas aeruginosa is commonly present in lungs of cystic fibrosis (CF) 2 and immunocompromised patients (1,2). The bacterium secretes a large number of products that contribute to virulence.…”

“…The present experiments were therefore designed to test the hypothesis that PYO activates inflammatory signaling by triggering production of the reactive oxygen species O 2 . , H 2 O 2 , and HO ⅐ that then oxidize the cytosol and activate NF-B.…”