primary-human-nasal-epithelial-cells-biobanking-context-precision

Primary Human Nasal Epithelial Cells: Biobanking in the Context of Precision Medicine

Human nasal epithelial (HNE) cells are easy to collect by simple, non-invasive nasal brushing. Patient-derived primary HNE cells can be amplified and ...

Institut Necker Enfants Malades

Université de paris

Université Paris Cité

Available corrector drugs are unable to effectively rescue the folding defects of CFTR-ΔF508 (or CFTR-F508del﻿), the most common disease-causing mutation of the cystic fibrosis transmembrane conductance regulator, a plasma membrane (PM) anion channel, and thus to substantially ameliorate clinical phenotypes of cystic fibrosis (CF). To overcome the corrector efficacy ceiling, here we show that compounds targeting distinct structural defects of CFTR can synergistically rescue mutant expression and function at the PM. High-throughput cell-based screens and mechanistic analysis identified three small-molecule series that target defects at nucleotide-binding domain (NBD1), NBD2 and their membrane-spanning domain (MSD) interfaces. Although individually these compounds marginally improve ΔF508-CFTR folding efficiency, function and stability, their combinations lead to ~50-100% of wild-type-level correction in immortalized and primary human airway epithelia and in mouse nasal epithelia. Likewise, corrector combinations were effective against rare missense mutations in various CFTR domains, probably acting via structural allostery, suggesting a mechanistic framework for their broad application.

Structure-guided combination therapy to potently improve the function of mutant CFTRs.

Cystic fibrosis (CF) is caused by defective Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. Morbidity is mainly due to early airway infection. We hypothesized that S. aureus clearance during the first hours of infection was impaired in CF human Airway Surface Liquid (ASL) because of a lowered pH. The ASL pH of human bronchial epithelial cell lines and primary respiratory cells from healthy controls (WT) and patients with CF was measured with a pH microelectrode. The antimicrobial capacity of airway cells was studied after S. aureus apical infection by counting surviving bacteria. ASL was significantly more acidic in CF than in WT respiratory cells. This was consistent with a defect in bicarbonate secretion involving CFTR and SLC26A4 (pendrin) and a persistent proton secretion by ATP12A. ASL demonstrated a defect in S. aureus clearance which was improved by pH normalization. Pendrin inhibition in WT airways recapitulated the CF airway defect and increased S. aureus proliferation. ATP12A inhibition by ouabain decreased bacterial proliferation. Antimicrobial peptides LL-37 and hBD1 demonstrated a pH-dependent activity. Normalizing ASL pH might improve innate airway defense in newborns with CF during onset of S. aureus infection. Pendrin activation and ATP12A inhibition could represent novel therapeutic strategies to normalize pH in CF airways.

Airway surface liquid acidification initiates host defense abnormalities in Cystic Fibrosis.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Author Correction: Airway surface liquid acidification initiates host defense abnormalities in Cystic Fibrosis.

Knowledge on the mechanisms of acid and base secretion in airways has progressed recently. The aim of this review is to summarize the known mechanisms of airway surface liquid (ASL) pH regulation and their implication in lung diseases. Normal ASL is slightly acidic relative to the interstitium, and defects in ASL pH regulation are associated with various respiratory diseases, such as cystic fibrosis. Basolateral bicarbonate (HCO) entry occurs via the electrogenic, coupled transport of sodium (Na) and HCO, and, together with carbonic anhydrase enzymatic activity, provides HCO for apical secretion. The latter mainly involves CFTR, the apical chloride/bicarbonate exchanger pendrin and paracellular transport. Proton (H) secretion into ASL is crucial to maintain its relative acidity compared to the blood. This is enabled by H apical secretion, mainly involving H/K ATPase and vacuolar H-ATPase that carry H against the electrochemical potential gradient. Paracellular HCO transport, the direction of which depends on the ASL pH value, acts as an ASL protective buffering mechanism. How the transepithelial transport of H and HCO is coordinated to tightly regulate ASL pH remains poorly understood, and should be the focus of new studies.

Airway Surface Liquid pH Regulation in Airway Epithelium Current Understandings and Gaps in Knowledge.

A reduction in pulmonary artery relaxation is a key event in the pathogenesis of pulmonary arterial hypertension (PAH). Cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction in airway epithelial cells plays a central role in cystic fibrosis; CFTR is also expressed in pulmonary arteries and has been shown to control endothelium-independent relaxation.

Article	Year
Structure-guided combination therapy to potently improve the function of mutant CFTRs. Nature medicine\| PubMed ID: 30297908	2018
Airway surface liquid acidification initiates host defense abnormalities in Cystic Fibrosis. Scientific reports\| PubMed ID: 31019198	2019
Author Correction: Airway surface liquid acidification initiates host defense abnormalities in Cystic Fibrosis. Scientific reports\| PubMed ID: 31754179	2019
Airway Surface Liquid pH Regulation in Airway Epithelium Current Understandings and Gaps in Knowledge. International journal of molecular sciences\| PubMed ID: 33806154	2021
Involvement of CFTR in the pathogenesis of pulmonary arterial hypertension. The European respiratory journal\| PubMed ID: 33926975	2021

Elise Dreano

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