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Thickness of the airway surface liquid layer in the lung is affected in cystic fibrosis by compromised synergistic regulation of the ENaC ion channel.

ABSTRACT: The lung epithelium is lined with a layer of airway surface liquid (ASL) that is crucial for healthy lung function. ASL thickness is controlled by two ion channels: epithelium sodium channel (ENaC) and cystic fibrosis (CF) transmembrane conductance regulator (CFTR). Here, we present a minimal mathematical model of ENaC, CFTR and ASL regulation that sheds light on the control of ENaC by the short palate lung and nasal epithelial clone 1 (SPLUNC1) protein and by phosphatidylinositol 4,5-biphosphate (PI(4,5)P2). The model, despite its simplicity, yields a good fit to experimental observations and is an effective tool for exploring the interplay between ENaC, CFTR and ASL. Steady-state data and dynamic information constrain the model's parameters without ambiguities. Testing the hypothesis that PI(4,5)P2 protects ENaC from ubiquitination suggests that this protection does not improve the model results and that the control of the ENaC opening probability by PI(4,5)P2 is sufficient to explain all available data. The model analysis further demonstrates that ASL at the steady state is sensitive to small changes in PI(4,5)P2 abundance, particularly in CF conditions, which suggests that manipulation of phosphoinositide metabolism may promote therapeutic benefits for CF patients.

SUBMITTER: Olivenca DV

PROVIDER: S-EPMC6731490 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Thickness of the airway surface liquid layer in the lung is affected in cystic fibrosis by compromised synergistic regulation of the ENaC ion channel.

Olivença Daniel V DV Fonseca Luis L LL Voit Eberhard O EO Pinto Francisco R FR

Journal of the Royal Society, Interface 20190828 157

The lung epithelium is lined with a layer of airway surface liquid (ASL) that is crucial for healthy lung function. ASL thickness is controlled by two ion channels: epithelium sodium channel (ENaC) and cystic fibrosis (CF) transmembrane conductance regulator (CFTR). Here, we present a minimal mathematical model of ENaC, CFTR and ASL regulation that sheds light on the control of ENaC by the short palate lung and nasal epithelial clone 1 (SPLUNC1) protein and by phosphatidylinositol 4,5-biphosphat ...[more]

PMID: 31455163

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Project description:Key pointsCl- and HCO3 - had similar paracellular permeabilities in human airway epithelia. PCl /PNa of airway epithelia was unaltered by pH 7.4 vs. pH 6.0 solutions. Under basal conditions, calculated paracellular HCO3 - flux was secretory. Cytokines that increased airway surface liquid pH decreased or reversed paracellular HCO3 - flux. HCO3 - flux through the paracellular pathway may counterbalance effects of cellular H+ and HCO3 - secretion.AbstractAirway epithelia control the pH of airway surface liquid (ASL), thereby optimizing respiratory defences. Active H+ and HCO3 - secretion by airway epithelial cells produce an ASL that is acidic compared with the interstitial space. The paracellular pathway could provide a route for passive HCO3 - flux that also modifies ASL pH. However, there is limited information about paracellular HCO3 - flux, and it remains uncertain whether an acidic pH produced by loss of cystic fibrosis transmembrane conductance regulator anion channels or proinflammatory cytokines might alter the paracellular pathway function. To investigate paracellular HCO3 - transport, we studied differentiated primary cultures of human cystic fibrosis (CF) and non-CF airway epithelia. The paracellular pathway was pH-insensitive at pH 6.0 vs. pH 7.4 and was equally permeable to Cl- and HCO3 - . Under basal conditions at pH ∼6.6, calculated paracellular HCO3 - flux was weakly secretory. Treating epithelia with IL-17 plus TNFα alkalinized ASL pH to ∼7.0, increased paracellular HCO3 - permeability, and paracellular HCO3 - flux was negligible. Applying IL-13 increased ASL pH to ∼7.4 without altering paracellular HCO3 - permeability, and calculated paracellular HCO3 - flux was absorptive. These results suggest that HCO3 - flux through the paracellular pathway counterbalances, in part, changes in the ASL pH produced via cellular mechanisms. As the pH of ASL increases towards that of basolateral liquid, paracellular HCO3 - flux becomes absorptive, tempering the alkaline pH generated by transcellular HCO3 - secretion.

Dataset Information

Thickness of the airway surface liquid layer in the lung is affected in cystic fibrosis by compromised synergistic regulation of the ENaC ion channel.

Publications

Thickness of the airway surface liquid layer in the lung is affected in cystic fibrosis by compromised synergistic regulation of the ENaC ion channel.

Similar Datasets

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