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Hill DB, Button B, Rubinstein M, Boucher RC. Physiology and pathophysiology of human airway mucus. Physiol Rev 2022; 102:1757-1836. [PMID: 35001665 PMCID: PMC9665957 DOI: 10.1152/physrev.00004.2021] [Citation(s) in RCA: 90] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 12/13/2021] [Accepted: 12/19/2021] [Indexed: 01/27/2023] Open
Abstract
The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas-liquid pumping and cough-dependent mechanisms, and mucus transport rates are heavily dependent on mucus concentration. Importantly, mucus transport rates are accurately predicted by the gel-on-brush model of the mucociliary apparatus from the relative osmotic moduli of the mucus and periciliary-glycocalyceal (PCL-G) layers. The fluid available to hydrate mucus is generated by transepithelial fluid transport. Feedback interactions between mucus concentrations and cilia beating, via purinergic signaling, coordinate Na+ absorptive vs Cl- secretory rates to maintain mucus hydration in health. In disease, mucus becomes hyperconcentrated (dehydrated). Multiple mechanisms derange the ion transport pathways that normally hydrate mucus in muco-obstructive lung diseases, e.g., cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), non-CF bronchiectasis (NCFB), and primary ciliary dyskinesia (PCD). A key step in muco-obstructive disease pathogenesis is the osmotic compression of the mucus layer onto the airway surface with the formation of adherent mucus plaques and plugs, particularly in distal airways. Mucus plaques create locally hypoxic conditions and produce airflow obstruction, inflammation, infection, and, ultimately, airway wall damage. Therapies to clear adherent mucus with hydrating and mucolytic agents are rational, and strategies to develop these agents are reviewed.
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Affiliation(s)
- David B Hill
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, North Carolina
| | - Brian Button
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michael Rubinstein
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Mechanical Engineering and Materials Science, Biomedical Engineering, Physics, and Chemistry, Duke University, Durham, North Carolina
| | - Richard C Boucher
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Mukherjee A, MacDonald KD, Kim J, Henderson MI, Eygeris Y, Sahay G. Engineered mutant α-ENaC subunit mRNA delivered by lipid nanoparticles reduces amiloride currents in cystic fibrosis-based cell and mice models. SCIENCE ADVANCES 2020; 6:6/47/eabc5911. [PMID: 33208364 PMCID: PMC7673816 DOI: 10.1126/sciadv.abc5911] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 10/05/2020] [Indexed: 05/02/2023]
Abstract
Cystic fibrosis (CF) results from mutations in the chloride-conducting CF transmembrane conductance regulator (CFTR) gene. Airway dehydration and impaired mucociliary clearance in CF is proposed to result in tonic epithelial sodium channel (ENaC) activity, which drives amiloride-sensitive electrogenic sodium absorption. Decreasing sodium absorption by inhibiting ENaC can reverse airway surface liquid dehydration. Here, we inhibit endogenous heterotrimeric ENaC channels by introducing inactivating mutant ENaC α mRNA (αmutENaC). Lipid nanoparticles carrying αmutENaC were transfected in CF-based airway cells in vitro and in vivo. We observed a significant decrease in macroscopic as well as amiloride-sensitive ENaC currents and an increase in airway surface liquid height in CF airway cells. Similarly, intranasal transfection of αmutENaC mRNA decreased amiloride-sensitive nasal potential difference in CFTRKO mice. These data suggest that mRNA-based ENaC inhibition is a powerful strategy for reducing mucus dehydration and has therapeutic potential for treating CF in all patients, independent of genotype.
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Affiliation(s)
- Anindit Mukherjee
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA
| | - Kelvin D MacDonald
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA
- Department of Pediatrics, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Jeonghwan Kim
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA
| | - Michael I Henderson
- Department of Cell, Developmental and Cancer Biology, Oregon Health & Science University, Portland, OR 97201, USA
| | - Yulia Eygeris
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA
| | - Gaurav Sahay
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA.
- Department of Biomedical Engineering, Robertson Life Sciences Building, Oregon Health & Science University, Portland, OR 97239, USA
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Chang J, Chen Z, Zhao R, Nie HG, Ji HL. Ion transport mechanisms for smoke inhalation-injured airway epithelial barrier. Cell Biol Toxicol 2020; 36:571-589. [PMID: 32588239 DOI: 10.1007/s10565-020-09545-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 06/17/2020] [Indexed: 10/24/2022]
Abstract
Smoke inhalation injury is the leading cause of death in firefighters and victims. Inhaled hot air and toxic smoke are the predominant hazards to the respiratory epithelium. We aimed to analyze the effects of thermal stress and smoke aldehyde on the permeability of the airway epithelial barrier. Transepithelial resistance (RTE) and short-circuit current (ISC) of mouse tracheal epithelial monolayers were digitized by an Ussing chamber setup. Zonula occludens-1 tight junctions were visualized under confocal microscopy. A cell viability test and fluorescein isothiocyanate-dextran assay were performed. Thermal stress (40 °C) decreased RTE in a two-phase manner. Meanwhile, thermal stress increased ISC followed by its decline. Na+ depletion, amiloride (an inhibitor for epithelial Na+ channels [ENaCs]), ouabain (a blocker for Na+/K+-ATPase), and CFTRinh-172 (a blocker of cystic fibrosis transmembrane regulator [CFTR]) altered the responses of RTE and ISC to thermal stress. Steady-state 40 °C increased activity of ENaCs, Na+/K+-ATPase, and CFTR. Acrolein, one of the main oxidative unsaturated aldehydes in fire smoke, eliminated RTE and ISC. Na+ depletion, amiloride, ouabain, and CFTRinh-172 suppressed acrolein-sensitive ISC, but showed activating effects on acrolein-sensitive RTE. Thermal stress or acrolein disrupted zonula occludens-1 tight junctions, increased fluorescein isothiocyanate-dextran permeability but did not cause cell death or detachment. The synergistic effects of thermal stress and acrolein exacerbated the damage to monolayers. In conclusion, the paracellular pathway mediated by the tight junctions and the transcellular pathway mediated by active and passive ion transport pathways contribute to impairment of the airway epithelial barrier caused by thermal stress and acrolein. Graphical abstract Thermal stress and acrolein are two essential determinants for smoke inhalation injury, impairing airway epithelial barrier. Transcellular ion transport pathways via the ENaC, CFTR, and Na/K-ATPase are interrupted by both thermal stress and acrolein, one of the most potent smoke toxins. Heat and acrolein damage the integrity of the airway epithelium through suppressing and relocating the tight junctions.
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Affiliation(s)
- Jianjun Chang
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, 11937 US Hwy 271, Tyler, TX, 75708, USA.,Institute of Health Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Zaixing Chen
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, 11937 US Hwy 271, Tyler, TX, 75708, USA.,School of Pharmacy, China Medical University, Shenyang, 110122, Liaoning, China
| | - Runzhen Zhao
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, 11937 US Hwy 271, Tyler, TX, 75708, USA
| | - Hong-Guang Nie
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, 110122, Liaoning, China.
| | - Hong-Long Ji
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, 11937 US Hwy 271, Tyler, TX, 75708, USA. .,Texas Lung Injury Institute, University of Texas Health Science Center at Tyler, Tyler, TX, 75708, USA.
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The Role of MicroRNA in the Airway Surface Liquid Homeostasis. Int J Mol Sci 2020; 21:ijms21113848. [PMID: 32481719 PMCID: PMC7312818 DOI: 10.3390/ijms21113848] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 05/24/2020] [Accepted: 05/25/2020] [Indexed: 02/06/2023] Open
Abstract
Mucociliary clearance, mediated by a coordinated function of cilia bathing in the airway surface liquid (ASL) on the surface of airway epithelium, protects the host from inhaled pathogens and is an essential component of the innate immunity. ASL is composed of the superficial mucus layer and the deeper periciliary liquid. Ion channels, transporters, and pumps coordinate the transcellular and paracellular movement of ions and water to maintain the ASL volume and mucus hydration. microRNA (miRNA) is a class of non-coding, short single-stranded RNA regulating gene expression by post-transcriptional mechanisms. miRNAs have been increasingly recognized as essential regulators of ion channels and transporters responsible for ASL homeostasis. miRNAs also influence the airway host defense. We summarize the most up-to-date information on the role of miRNAs in ASL homeostasis and host-pathogen interactions in the airway and discuss concepts for miRNA-directed therapy.
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Garth J, Easter M, Skylar Harris E, Sailland J, Kuenzi L, Chung S, Dennis JS, Baumlin N, Adewale AT, Rowe SM, King G, Faul C, Barnes JW, Salathe M, Krick S. The Effects of the Anti-aging Protein Klotho on Mucociliary Clearance. Front Med (Lausanne) 2020; 6:339. [PMID: 32039219 PMCID: PMC6992571 DOI: 10.3389/fmed.2019.00339] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/24/2019] [Indexed: 01/23/2023] Open
Abstract
α-klotho (KL) is an anti-aging protein and has been shown to exert anti-inflammatory and anti-oxidative effects in the lung and pulmonary diseases such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis. The current study investigated the direct effect of KL on the bronchial epithelium in regards to mucociliary clearance parameters. Primary human bronchial and murine tracheal epithelial cells, cultured, and differentiated at the air liquid interface (ALI), were treated with recombinant KL or infected with a lentiviral vector expressing KL. Airway surface liquid (ASL) volume, airway ion channel activities, and expression levels were analyzed. These experiments were paired with ex vivo analyses of mucociliary clearance in murine tracheas from klotho deficient mice and their wild type littermates. Our results showed that klotho deficiency led to impaired mucociliary clearance with a reduction in ASL volume in vitro and ex vivo. Overexpression or exogenous KL increased ASL volume, which was paralleled by increased activation of the large-conductance, Ca2+-activated, voltage-dependent potassium channel (BK) without effect on the cystic fibrosis transmembrane conductance regulator (CFTR). Furthermore, KL overexpression downregulated IL-8 levels and attenuated TGF-β-mediated downregulation of LRRC26, the γ subunit of BK, necessary for its function in non-excitable cells. In summary, we show that KL regulates mucociliary function by increasing ASL volume in the airways possibly due to underlying BK activation. The KL mediated BK channel activation may be a potentially important target to design therapeutic strategies in inflammatory airway diseases when ASL volume is decreased.
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Affiliation(s)
- Jaleesa Garth
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Molly Easter
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Elex Skylar Harris
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Juliette Sailland
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Lisa Kuenzi
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Samuel Chung
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - John S. Dennis
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - Nathalie Baumlin
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - Adegboyega T. Adewale
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - Steven M. Rowe
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Gwendalyn King
- Department of Biology, Creighton University, Omaha, NE, United States
| | - Christian Faul
- Division of Nephrology, Department of Medicine, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jarrod W. Barnes
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Matthias Salathe
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - Stefanie Krick
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, AL, United States
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A physiologically-motivated model of cystic fibrosis liquid and solute transport dynamics across primary human nasal epithelia. J Pharmacokinet Pharmacodyn 2019; 46:457-472. [PMID: 31494805 DOI: 10.1007/s10928-019-09649-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/02/2019] [Indexed: 11/27/2022]
Abstract
Cystic fibrosis (CF) disease is caused by mutations affecting the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel expressed in the mucosal side of epithelial tissue. In the airway, dysfunctional CFTR results in a transepithelial osmotic imbalance leading to hyperabsorption of airway surface liquid mucostasis, chronic inflammation, and eventual respiratory failure. Human nasal epithelial cell cultures from healthy and CF donors were used to perform studies of liquid and solute transport dynamics at an air/liquid interface in order to emulate the in vivo airway. Then, these results were used to inform a quantitative systems pharmacology model of airway epithelium describing electrically and chemically driven transcellular ionic transport, contributions of both convective and diffusive paracellular solute transport, and osmotically driven transepithelial water dynamics. Model predictions showed CF cultures, relative to non-CF ones, have increased apical and basolateral water permeabilities, and increase paracellular permeability and transepithelial chemical driving force for a radiolabeled tracer used to track small molecule absorption. These results provide a computational platform to better understand and probe the mechanisms behind the liquid hyperabsorption and small molecule retention profiles observed in the CF airway.
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Abstract
Mucociliary clearance is critically important in protecting the airways from infection and from the harmful effects of smoke and various inspired substances known to induce oxidative stress and persistent inflammation. An essential feature of the clearance mechanism involves regulation of the periciliary liquid layer on the surface of the airway epithelium, which is necessary for normal ciliary beating and maintenance of mucus hydration. The underlying ion transport processes associated with airway surface hydration include epithelial Na+ channel-dependent Na+ absorption occurring in parallel with CFTR and Ca2+-activated Cl- channel-dependent anion secretion, which are coordinately regulated to control the depth of the periciliary liquid layer. Oxidative stress is known to cause both acute and chronic effects on airway ion transport function, and an increasing number of studies in the past few years have identified an important role for autophagy as part of the physiological response to the damaging effects of oxidation. In this review, recent studies addressing the influence of oxidative stress and autophagy on airway ion transport pathways, along with results showing the potential of autophagy modulators in restoring the function of ion channels involved in transepithelial electrolyte transport necessary for effective mucociliary clearance, are presented.
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Affiliation(s)
- Scott M O'Grady
- Departments of Animal Science, Integrative Biology and Physiology, University of Minnesota , St. Paul, Minnesota
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8
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ATP12A promotes mucus dysfunction during Type 2 airway inflammation. Sci Rep 2018; 8:2109. [PMID: 29391451 PMCID: PMC5794982 DOI: 10.1038/s41598-018-20444-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/16/2018] [Indexed: 12/23/2022] Open
Abstract
Allergic airway disease is known to cause significant morbidity due to impaired mucociliary clearance, however the mechanism that leads to the mucus dysfunction is not entirely understood. Interleukin 13 (IL-13), a key mediator of Type 2 (T2) inflammation, profoundly alters the ion transport properties of airway epithelium. However, these electrophysiological changes cannot explain the thick, tenacious airway mucus that characterizes the clinical phenotype. Here we report that IL-13 dramatically increases the airway surface liquid (ASL) viscosity in cultured primary human bronchial epithelial cells and thereby inhibits mucus clearance. These detrimental rheological changes require ATP12A, a non-gastric H+/K+-ATPase that secretes protons into the ASL. ATP12A knockdown or inhibition prevented the IL-13 dependent increase in ASL viscosity but did not alter the ASL pH. We propose that ATP12A promotes airway mucus dysfunction in individuals with T2 inflammatory airway diseases and that ATP12A may be a novel therapeutic target to improve mucus clearance.
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Newby JM, Seim I, Lysy M, Ling Y, Huckaby J, Lai SK, Forest MG. Technological strategies to estimate and control diffusive passage times through the mucus barrier in mucosal drug delivery. Adv Drug Deliv Rev 2018; 124:64-81. [PMID: 29246855 PMCID: PMC5809312 DOI: 10.1016/j.addr.2017.12.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 12/05/2017] [Accepted: 12/06/2017] [Indexed: 01/05/2023]
Abstract
In mucosal drug delivery, two design goals are desirable: 1) insure drug passage through the mucosal barrier to the epithelium prior to drug removal from the respective organ via mucus clearance; and 2) design carrier particles to achieve a prescribed arrival time and drug uptake schedule at the epithelium. Both goals are achievable if one can control "one-sided" diffusive passage times of drug carrier particles: from deposition at the mucus interface, through the mucosal barrier, to the epithelium. The passage time distribution must be, with high confidence, shorter than the timescales of mucus clearance to maximize drug uptake. For 100nm and smaller drug-loaded nanoparticulates, as well as pure drug powders or drug solutions, diffusion is normal (i.e., Brownian) and rapid, easily passing through the mucosal barrier prior to clearance. Major challenges in quantitative control over mucosal drug delivery lie with larger drug-loaded nanoparticulates that are comparable to or larger than the pores within the mucus gel network, for which diffusion is not simple Brownian motion and typically much less rapid; in these scenarios, a timescale competition ensues between particle passage through the mucus barrier and mucus clearance from the organ. In the lung, as a primary example, coordinated cilia and air drag continuously transport mucus toward the trachea, where mucus and trapped cargo are swallowed into the digestive tract. Mucus clearance times in lung airways range from minutes to hours or significantly longer depending on deposition in the upper, middle, lower airways and on lung health, giving a wide time window for drug-loaded particle design to achieve controlled delivery to the epithelium. We review the physical and chemical factors (of both particles and mucus) that dictate particle diffusion in mucus, and the technological strategies (theoretical and experimental) required to achieve the design goals. First we describe an idealized scenario - a homogeneous viscous fluid of uniform depth with a particle undergoing passive normal diffusion - where the theory of Brownian motion affords the ability to rigorously specify particle size distributions to meet a prescribed, one-sided, diffusive passage time distribution. Furthermore, we describe how the theory of Brownian motion provides the scaling of one-sided diffusive passage times with respect to mucus viscosity and layer depth, and under reasonable caveats, one can also prescribe passage time scaling due to heterogeneity in viscosity and layer depth. Small-molecule drugs and muco-inert, drug-loaded carrier particles 100nm and smaller fall into this class of rigorously controllable passage times for drug delivery. Second we describe the prevalent scenarios in which drug-loaded carrier particles in mucus violate simple Brownian motion, instead exhibiting anomalous sub-diffusion, for which all theoretical control over diffusive passage times is lost, and experiments are prohibitive if not impossible to measure one-sided passage times. We then discuss strategies to overcome these roadblocks, requiring new particle-tracking experiments and emerging advances in theory and computation of anomalous, sub-diffusive processes that are necessary to predict and control one-sided particle passage times from deposition at the mucosal interface to epithelial uptake. We highlight progress to date, remaining hurdles, and prospects for achieving the two design goals for 200nm and larger, drug-loaded, non-dissolving, nanoparticulates.
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Affiliation(s)
- Jay M Newby
- Department of Mathematics and Applied Physical Sciences, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, United States
| | - Ian Seim
- Department of Mathematics and Applied Physical Sciences, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, United States
| | - Martin Lysy
- Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, ON N2L 3G1, United States
| | - Yun Ling
- Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, ON N2L 3G1, United States
| | - Justin Huckaby
- Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, United States
| | - Samuel K Lai
- Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, United States; UNC-NCSU Joint Department of Biomedical Engineering, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, United States; Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, United States
| | - M Gregory Forest
- Department of Mathematics and Applied Physical Sciences, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, United States; UNC-NCSU Joint Department of Biomedical Engineering, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, United States.
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Role of Smad3 and p38 Signalling in Cigarette Smoke-induced CFTR and BK dysfunction in Primary Human Bronchial Airway Epithelial Cells. Sci Rep 2017; 7:10506. [PMID: 28874823 PMCID: PMC5585359 DOI: 10.1038/s41598-017-11038-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/18/2017] [Indexed: 01/26/2023] Open
Abstract
Mucociliary clearance (MCC) is a major airway host defence system that is impaired in patients with smoking-associated chronic bronchitis. This dysfunction is partially related to a decrease of airway surface liquid (ASL) volume that is in part regulated by apically expressed cystic fibrosis transmembrane conductance regulator (CFTR) and large-conductance, Ca2+-activated, and voltage dependent K+ (BK) channels. Here, data from human bronchial epithelial cells (HBEC) confirm that cigarette smoke not only downregulates CFTR activity but also inhibits BK channel function, thereby causing ASL depletion. Inhibition of signalling pathways involved in cigarette smoke-induced channel dysfunction reveals that CFTR activity is downregulated via Smad3 signalling whereas BK activity is decreased via the p38 cascade. In addition, pre-treatment with pirfenidone, a drug presently used to inhibit TGF-β signalling in idiopathic pulmonary fibrosis, ameliorated BK dysfunction and ASL volume loss. Taken together, our results highlight the importance of not only CFTR but also BK channel function in maintaining ASL homeostasis and emphasize the possibility that pirfenidone could be employed as a novel therapeutic regimen to help improve MCC in smoking-related chronic bronchitis.
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Zaidman NA, Panoskaltsis-Mortari A, O'Grady SM. Large-conductance Ca 2+ -activated K + channel activation by apical P2Y receptor agonists requires hydrocortisone in differentiated airway epithelium. J Physiol 2017; 595:4631-4645. [PMID: 28481415 DOI: 10.1113/jp274200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 05/02/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Hydrocortisone (HC) is required for activation of large-conductance Ca2+ -activated K+ current (BK) by purinergic receptor agonists. HC reduces insertion of the stress-regulated exon (STREX) in the KCNMA1 gene, permitting protein kinase C (PKC)-dependent channel activation. Overlapping and unique purinergic signalling regions exist at the apical border of differentiated surface cells. BK channels localize in the cilia of surface cells. ABSTRACT In the present study we investigated the role of hydrocortisone (HC) on uridine-5'-triphosphate (UTP)-stimulated ion transport in differentiated, pseudostratified epithelia derived from normal human bronchial basal cells. The presence of a UTP-stimulated, paxilline-sensitive large-conductance Ca2+ -activated K+ (BK) current was demonstrated in control epithelia but was not stimulated in epithelia differentiated in the absence of HC (HC0). Addition of the BK channel opener NS11021 directly activated channels in control epithelia; however, under HC0 conditions, activation only occurred when UTP was added after NS11021. The PKC inhibitors GF109203x and Gö6983 blocked BK activation by UTP in control epithelia, suggesting that PKC-mediated phosphorylation plays a permissive role in purinoceptor-stimulated BK activation. Moreover, HC0 epithelia expressed significantly more KCNMA1 containing the stress-regulated exon (STREX), a splice-variant of the α-subunit that displays altered channel regulation by phosphorylation, compared to control epithelia. Furthermore, BK channels as well as purinergic receptors were shown to localize in unique and overlapping domains at the apical membrane of ciliated surface cells. These results establish a previously unrecognized role for glucocorticoids in regulation of BK channels in airway epithelial cells.
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Affiliation(s)
- Nathan A Zaidman
- Department of Integrative Biology and Physiology, University of Minnesota, 6-125 Jackson Hall, Minneapolis, MN, USA
| | - Angela Panoskaltsis-Mortari
- Department of Integrative Biology and Physiology, University of Minnesota, 6-125 Jackson Hall, Minneapolis, MN, USA.,Department of Pediatrics, University of Minnesota, 660E MCRB, Minneapolis, MN, USA
| | - Scott M O'Grady
- Department of Integrative Biology and Physiology, University of Minnesota, 6-125 Jackson Hall, Minneapolis, MN, USA.,Department of Animal Science, University of Minnesota, 480 Haecker Hall, St. Paul, Minneapolis, MN, USA
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