Abstract
Large-conductance, Ca2+-activated, voltage-dependent K+(BK) channel function is critical for adequate airway hydration and mucociliary function. In airway epithelia, BK function is regulated by its γ-subunit, leucine-rich repeat-containing protein 26 (LRRC26). Since patients with cystic fibrosis (CF)-related diabetes mellitus (CFRD) have worse lung function outcomes, this study determined the effects of hyperglycaemia on BK function in CF bronchial epithelial (CFBE) cellsin vitroand evaluated the correlation between glycaemic excursions and mRNA expression ofLRRC26in the upper airways of CF and CFRD patients.
CFBE cells were redifferentiated at the air–liquid interface (ALI) in media containing either 5.5 mM or 12.5 mM glucose. BK activity was measured in an Ussing chamber. Airway surface liquid (ASL) volume was estimated by meniscus scanning and inflammatory marker expression was measured by quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA). CF patients were assessed by 7 days of continuous glucose monitoring (CGM).LRRC26mRNA expression was measured by quantitative real-time PCR from nasal cells obtained at the end of glucose monitoring.
BK currents were significantly decreased in CFBE cells cultured under high glucose. These cells revealed significantly lower ASL volumes and increased inflammation, including the receptor for advanced glycation endproducts (RAGE), compared to cells cultured in normal glucose.In vivo, nasal cell expression ofLRRC26mRNA was inversely correlated with hyperglycaemic excursions, consistent with thein vitroresults.
Our findings demonstrate that hyperglycaemia induces inflammation and impairs BK channel function in CFBE cellsin vitro。这些数据表明,肺功能下降in CFRD patients may be related to BK channel dysfunction.
Abstract
In CF patients, hyperglycaemia downregulates airway epithelial BK channels that are critical for mucociliary clearance. Mechanistically, hyperglycaemia suppresses expression of the BK γ-subunitLRRC26, which is required for its function in the airway.https://bit.ly/315FCTV
Footnotes
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Author contributions: Conceived and designed the study: C.D. Bengtson, A. Anabtawi, N. Baumlin, M.D. Kim and M. Salathe. Executed experiments and analysed the data: all authors. Clinical study recruitment, data collection and data interpretation: C.D. Bengtson, A. Anabtawi, M.D. Kim and M. Salathe. Wrote the manuscript: C.D. Bengtson, M.D. Kim and M. Salathe. Discussed the results and commented on the manuscript: all authors.
Conflict of interest: C.D. Bengtson reports grants from the Cystic Fibrosis Foundation and NCATS, during the conduct of the study.
Conflict of interest: M.D. Kim reports grants from the NIH and the Cystic Fibrosis Foundation, during the conduct of the study; and grants from the Flight Attendant Medical Research Institute and the James and Esther King Florida Biomedical Research Program, outside the submitted work.
Conflict of interest: A. Anabtawi reports grants from the Cystic Fibrosis Foundation and University of Kansas Pilot Support, during the conduct of the study.
Conflict of interest: J. He reports grants from the Cystic Fibrosis Foundation, during the conduct of the study.
Conflict of interest: J.S. Dennis has nothing to disclose.
Conflict of interest: S. Miller has nothing to disclose.
Conflict of interest: M. Yoshida has nothing to disclose.
Conflict of interest: N. Baumlin reports grants from the NIH and the Cystic Fibrosis Foundation, during the conduct of the study; and grants from the Flight Attendant Medical Research Institute and the James and Esther King Florida Biomedical Research Program, outside the submitted work.
Conflict of interest: M. Salathe reports grants and personal fees from the NIH and the Cystic Fibrosis Foundation, during the conduct of the study; grants and personal fees from Arrowhead Pharmaceuticals and the Flight Attendant Medical Research Institute, outside the submitted work; and grants from the COPD Foundation and the James and Esther King Florida Biomedical Research Program, outside the submitted work.
Support statement: This study was funded in part by the Cystic Fibrosis Foundation (SALATH18I0, BENGTS19AC0), the National Heart, Lung, and Blood Institute (NHLBI) (R01 HL-133240) and a CTSA TL-1 training grant under UL1-TR002366 (NCATS) awarded to the University of Kansas for Frontiers: University of Kansas Clinical and Translational Science Institute (TL1TR002368). The contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health (NIH) or NCATS. Funding information for this article has been deposited with theCrossref Funder Registry。
- ReceivedMarch 1, 2020.
- AcceptedJuly 20, 2020.
- Copyright ©ERS 2021