Anti-Infectives Restore ORKAMBI® Rescue of F508del-CFTR Function in Human Bronchial Epithelial Cells Infected with Clinical Strains of P. aeruginosa.

Onofrio Laselva,Christine E Bear,Tracy A Stone,Charles M Deber

doi:10.3390/biom10020334

Onofrio Laselva, Christine E Bear + Show 2 more

Open Access

https://doi.org/10.3390/biom10020334

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Journal: Biomolecules	Publication Date: Feb 19, 2020
Citations: 32	License type: CC BY 4.0

Affiliation: Hospital for Sick Children, University of Toronto

Abstract

Chronic infection and inflammation are the primary causes of declining lung function in Cystic Fibrosis (CF) patients. ORKAMBI® (Lumacaftor-Ivacaftor) is an approved combination therapy for Cystic Fibrosis (CF) patients bearing the most common mutation, F508del, in the cystic fibrosis conductance regulator (CFTR) protein. It has been previously shown that ORKAMBI®-mediated rescue of CFTR is reduced by a pre-existing Pseudomonas aeruginosa infection. Here, we show that the infection of F508del-CFTR human bronchial epithelial (HBE) cells with lab strain and four different clinical strains of P. aeruginosa, isolated from the lung sputum of CF patients, decreases CFTR function in a strain-specific manner by 48 to 88%. The treatment of infected cells with antibiotic tobramycin or cationic antimicrobial peptide 6K-F17 was found to decrease clinical strain bacterial growth on HBE cells and restore ORKAMBI®-mediated rescue of F508del-CFTR function. Further, 6K-F17 was found to downregulate the expression of pro-inflammatory cytokines, interleukin (IL)-8, IL-6, and tumor necrosis factor-α in infected HBE cells. The results provide strong evidence for a combination therapy approach involving CFTR modulators and anti-infectives (i.e., tobramycin and/or 6K-F17) to improve their overall efficacy in CF patients.

Highlights

Cystic Fibrosis (CF) is a genetic disease that is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene [1,2,3]
We show the negative impact that P. aeruginosa infections have on WT- and F508del-CFTR function, and how the application of the anti-infectives tobramycin and 6K-F17 reverses infection-mediated decreases in CFTR function
The highest dose of 6K-F17 tested (128 μg/mL) decreased the PAO1 growth by over 80% on F508del-CFTR cells, confirming, for the first time, the ability of 6K-F17 to exhibit antimicrobial activity against P. aeruginosa bacteria that were grown atop human bronchial epithelial cells (HBE) cells (Figure 1; grey bars) and highlighting the difficulty in eliminating infections on top of F508del-CFTR cells vs. WT-CFTR cells

Summary

Introduction

Cystic Fibrosis (CF) is a genetic disease that is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene [1,2,3]. A deficient CFTR function causes the failure of chloride secretion and sodium hyperabsorption at the apical airway surface, leading to the dehydration of the airway surface, impaired mucociliary clearance, and the accumulation of viscous mucus at the epithelial surface [4,5]. Prolonged P. aeruginosa infections have been linked to chronic inflammation in the CF lung [7,8], worsening the damage to lung tissue, and leading to eventual respiratory failure [9]. More than 2000 CF-causing mutations have been identified (www.genet.sickkids.on.ca; www.CFTR2.org). The most common mutation, the deletion of phenylalanine at position 508 (F508del-CFTR), induces the misfolding of the protein, causing retention in the ER and degradation by proteasomal pathways [10]

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