Cyclodextrins reduce the ability of Pseudomonas aeruginosa outer-membrane vesicles to reduce CFTR Cl⁻ secretion

Abstract

Pseudomonas aeruginosa secretes outer-membrane vesicles (OMVs) that fuse with cholesterol-rich lipid rafts in the apical membrane of airway epithelial cells and decrease wt-CFTR Cl− secretion. Herein, we tested the hypothesis that a reduction of the cholesterol content of CF human airway epithelial cells by cyclodextrins reduces the inhibitory effect of OMVs on VX-809 (lumacaftor)-stimulated Phe508del CFTR Cl− secretion. Primary CF bronchial epithelial cells and CFBE cells were treated with vehicle, hydroxypropyl-β-cyclodextrin (HPβCD), or methyl-β-cyclodextrin (MβCD), and the effects of OMVs secreted by P. aeruginosa on VX-809 stimulated Phe508del CFTR Cl− secretion were measured in Ussing chambers. Neither HPβCD nor MβCD were cytotoxic, and neither altered Phe508del CFTR Cl− secretion. Both cyclodextrins reduced OMV inhibition of VX-809-stimulated Phe508del-CFTR Cl− secretion when added to the apical side of CF monolayers. Both cyclodextrins also reduced the ability of P. aeruginosa to form biofilms and suppressed planktonic growth of P. aeruginosa. Our data suggest that HPβCD, which is in clinical trials for Niemann-Pick Type C disease, and MβCD, which has been approved by the U.S. Food and Drug Administration for use in solubilizing lipophilic drugs, may enhance the clinical efficacy of VX-809 in CF patients when added to the apical side of airway epithelial cells, and reduce planktonic growth and biofilm formation by P. aeruginosa. Both effects would be beneficial to CF patients.

Bacterial Membrane Vesicles in Pneumonia: From Mediators of Virulence to Innovative Vaccine Candidates

“…Upon colonialization of the mucosal surfaces of bronchi and bronchioles, and/or the alveolar compartment with bacterial pathogens the epithelial barrier forms the primary antimicrobial barrier but concomitantly also the first surface of interaction with (O)MVs. (O)MVs bind to the bronchial epithelium, as shown for P. aeruginosa OMVs [ 69 ], and alveolar epithelial cells, as demonstrated for A. baumannii OMVs and S. pneumoniae MVs [ 51 , 70 ]. Notably, for EVs an important role of CD44 in the EV binding process has been well documented [ 71 , 72 ].…”

“…Accordingly, inhibitory effects on residual CFTR should be avoided as they further worsen the clinical outcome in CF patients. P. aeruginosa —being one of the main infectious agents in CF—releases OMVs that bind to airway epithelial cells and interact specifically with cholesterol-rich lipid rafts and the neural Wiskott–Aldrich syndrome protein (N-WASP), which mediates the interaction of extracellular ligands with the actin cytoskeleton [ 69 , 75 ]. P. aeruginosa -secreted OMVs transport various virulence factors, i.e., β-lactamases, hemolytic phospholipase C, and, as aforementioned, Cif [ 75 ].…”

“…Hence, P. aeruginosa OMVs may initiate a vicious cycle of opportunistic infection resulting in a worsening of mucociliary clearance and restriction of a competent immune response, which further increase the susceptibility to bacterial and other infections. An initial approach to overcome this pathophysiology by reducing membrane cholesterol by cyclodextrins (hydroxy-propyl-β-cyclodextrin and methyl-β-cyclodextrin) proved efficient in limiting the binding of P. aeruginosa -released OMVs to epithelial lipid rafts and thus restoring Cl − secretion in airway epithelial cells in vitro [ 69 ]. Future research will have to probe whether strategies to reduce membrane cholesterol levels in vivo by, e.g., statins or dietary restrictions may similarly reduce OMV-binding to epithelial target cells and thus overall bacterial pathogenicity.…”

Outer Membrane Lipid Secretion and the Innate Immune Response to Gram-Negative Bacteria

“…Lipid raft-mediated OMV entry was observed using infection models for Campylobacter jejuni, P. gingivalis, H. influenzae, and Pseudomonas aeruginosa (83,96,110,111). OMV fusion with lipid rafts might facilitate delivery of toxins and MAMPs into host cells to induce immune activation or cell death, but the chemical-physical mechanism of entry through rafts is not understood (84,85,110,(112)(113)(114)(115).…”

The Contribution of Membrane Vesicles to Bacterial Pathogenicity in Cystic Fibrosis Infections and Healthcare Associated Pneumonia

“…(Bomberger et al, 2009(Bomberger et al, , 2011Ballok et al, 2014;O'Donoghue and Krachler, 2016). Lowering the cholesterol content of CF airway epithelial cells (Phe508del) by cyclodextrin lowers the impact of P. aeruginosa vesicles on Cl − secretion after lumacaftor treatment (Barnaby et al, 2019).…”