IN VITRO AND IN SILICO CHARACTERIZATION OF HUMAN NASAL EPITHELIAL ION AND LIQUID TRANSPORT MECHANISMS
Authors: Castillo Florencio Serrano , Parker Robert S. , Corcoran Timothy E. , Meyer Hannah R. , Shapiro Monica E. , Betrand Carol A. 
Published: June 2021

Introduction

Cystic Fibrosis (CF) is a genetic disease caused by mutations in the CFTR gene, which codes for a widely expressed anion channel located in the apical membrane of epithelial cells. Loss of CFTR function results in an osmotic imbalance due to defective ion and water transport. Human bronchial epithelial cell cultures (HBE) are a well‐established experimental model of CF and show the same transport defects of the CF airway. More recently, human nasal epithelial cell cultures (HNE) have emerged as a novel alternative due to their accessibility and potential to allow for matched in vitro studies analogous to common clinical measurements. Here we implement a combination of experimental and computational approaches to facilitate the description of the ion and liquid transport functions of HNEs, and the role they may play in CF.

Methods

We have performed extensive characterization studies on well‐differentiated non‐CF HNE (n=9) and non‐CF HBE (n=12) to determine the extent of any possible physiological differences. This includes Ussing chamber studies to assess epithelial short‐circuit currents and resistance, apical volume regulation and paracellular flux assays, as measured by Tc99m‐DTPA (DTPA), to study response to volume challenges, and standard protein expression. We have also used this data to generate parametric fits of individual ion channel permeabilities, as predicted by a mathematical model of cell‐scale electrophysiology. Best parameter sets from each donor were estimated and compared against those from the opposite group to establish population differences according to a 2‐sample Kolmogorov‐Smirnov test.

Results

Our study shows HNE have a significant increase in the ENaC current (p<0.05), and a decrease in stimulated CFTR current (p<0.01) versus non‐CF HBEs. Similarly, thin film studies revealed significantly decreased DTPA retention, (p < 0.05), as well as apical volume at 12 and 24 hrs following an apical volume challenge (p<0.01). Donor‐specific parameter fits predicted statistically different parametric distributions for CFTR, ENaC, BKCa, and a basolateral Cl‐channel between the HBE and HNE population (p<0.01). Of note are the increased basolateral Cl− and BKCA permeabilities relative to CFTR permeability.

Conclusion

Our studies showed non‐CF HNEs have higher liquid absorption rates than non‐CF HBEs. This behavior may be correlated with the lower CFTR dependent Cl− current also seen in HNE. It could suggest that HNEs operate at a different homeostatic level than HBEs due to environmental differences between the bronchi and the paranasal sinus, or perhaps it is the result of distinct functional levels of members of the epithelial electrophysiology network. Similar studies exploring the extent of these physiological differences in CF HNEs, and carriers of a single CF mutation, are currently underway.

Support or Funding Information

Supported by NIH R01‐HL108929‐01, U01‐HL131046‐01, P30‐DK‐072506

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.