Chronic β2AR stimulation limits CFTR activation in human airway epithelia
John J. Brewington, … , L. Jason Lu, John P. Clancy
John J. Brewington, … , L. Jason Lu, John P. Clancy
Published February 22, 2018
Citation Information: JCI Insight. 2018;3(4):e93029. https://doi.org/10.1172/jci.insight.93029.
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Research Article Cell biology Pulmonology

Chronic β2AR stimulation limits CFTR activation in human airway epithelia

Abstract

Traditional pulmonary therapies for cystic fibrosis (CF) target the downstream effects of CF transmembrane conductance regulator (CFTR) dysfunction (the cause of CF). Use of one such therapy, β-adrenergic bronchodilators (such as albuterol), is nearly universal for airway clearance. Conversely, novel modulator therapies restore function to select mutant CFTR proteins, offering a disease-modifying treatment. Recent trials of modulators targeting F508del-CFTR, the most common CFTR mutation, suggest that chronic β-agonist use may undermine clinical modulator benefits. We therefore sought to understand the impact of chronic or excess β-agonist exposure on CFTR activation in human airway epithelium. The present studies demonstrate a greater than 60% reduction in both wild-type and modulator-corrected F508del-CFTR activation following chronic exposure to short- and long-acting β-agonists. This reduction was due to reduced cellular generation of cAMP downstream of the β-2 adrenergic receptor–G protein complex. Our results point towards a posttranscriptional reduction in adenylyl cyclase function as the mechanism of impaired CFTR activation produced by prolonged β-agonist exposure. β-Agonist–induced CFTR dysfunction was sufficient to abrogate VX809/VX770 modulation of F508del-CFTR in vitro. Understanding the clinical relevance of our observations is critical for CF patients using these drugs, and for investigators to inform future CFTR modulator drug trials.

Authors

John J. Brewington, Jessica Backstrom, Amanda Feldman, Elizabeth L. Kramer, Jessica D. Moncivaiz, Alicia J. Ostmann, Xiaoting Zhu, L. Jason Lu, John P. Clancy

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Figure 4

Chronic albuterol exposure reduces mucociliary clearance (MCC) in wtCFTR+ primary human airway epithelial cells (HAECs).

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Chronic albuterol exposure reduces mucociliary clearance (MCC) in wtCFTR...
wtCFTR+ primary HAECs were exposed to either albuterol (10 μM) or the CFTR inhibitor GlyH101 (50 μM) for 72 hours. Fluorescent microbeads were placed on the apical surface of the cells 72 hours prior to testing, allowing airway surface liquid to return to equilibrium. MCC rate was then calculated as speed of microbead transport, measured with fluorescence microscopy and single-particle tracking, and ciliary beat frequency (CBF) was measured with high-speed videomicroscopy. Seventy-two-hour pretreatment with either albuterol (10 μM) or the CFTR inhibitor GlyH101 (50 μM) resulted in a greater than 60% reduction in MCC rate (A, n = 3 inserts, >3,000 measurements per insert). Despite reduced mucus movement, CBF was not affected (B, n = 3 inserts, 20 measurements per insert). These experiments are representative of studies repeated in triplicate, with similar results. Data presented represent the mean ± SEM. Box whiskers range from minimum to maximum, with no data excluded. Boundaries of boxes represent 25th (lower) and 75th (upper) percentiles, while the central bar represents the median. *P < 0.05; ****P < 0.0005; NS, nonsignificant by 1-way ANOVA with Tukey’s multiple comparisons test.