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Okuda K, Dang H, Kobayashi Y, Carraro G, Nakano S, Chen G, Kato T, Asakura T, Gilmore RC, Morton LC, Lee RE, Mascenik T, Yin WN, Barbosa Cardenas SM, O'Neal YK, Minnick CE, Chua M, Quinney NL, Gentzsch M, Anderson CW, Ghio A, Matsui H, Nagase T, Ostrowski LE, Grubb BR, Olsen JC, Randell SH, Stripp BR, Tata PR, O'Neal WK, Boucher RC. Secretory Cells Dominate Airway CFTR Expression and Function in Human Airway Superficial Epithelia. Am J Respir Crit Care Med 2021; 203:1275-1289. [PMID: 33321047 DOI: 10.1164/rccm.202008-3198oc] [Citation(s) in RCA: 95] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rationale: Identification of the specific cell types expressing CFTR (cystic fibrosis [CF] transmembrane conductance regulator) is required for precision medicine therapies for CF. However, a full characterization of CFTR expression in normal human airway epithelia is missing. Objectives: To identify the cell types that contribute to CFTR expression and function within the proximal-distal axis of the normal human lung. Methods: Single-cell RNA (scRNA) sequencing (scRNA-seq) was performed on freshly isolated human large and small airway epithelial cells. scRNA in situ hybridization (ISH) and single-cell qRT-PCR were performed for validation. In vitro culture systems correlated CFTR function with cell types. Lentiviruses were used for cell type-specific transduction of wild-type CFTR in CF cells. Measurements and Main Results: scRNA-seq identified secretory cells as dominating CFTR expression in normal human large and, particularly, small airway superficial epithelia, followed by basal cells. Ionocytes expressed the highest CFTR levels but were rare, whereas the expression in ciliated cells was infrequent and low. scRNA ISH and single-cell qRT-PCR confirmed the scRNA-seq findings. CF lungs exhibited distributions of CFTR and ionocytes similar to those of normal control subjects. CFTR mediated Cl- secretion in cultures tracked secretory cell, but not ionocyte, densities. Furthermore, the nucleotide-purinergic regulatory system that controls CFTR-mediated hydration was associated with secretory cells and not with ionocytes. Lentiviral transduction of wild-type CFTR produced CFTR-mediated Cl- secretion in CF airway secretory cells but not in ciliated cells. Conclusions: Secretory cells dominate CFTR expression and function in human airway superficial epithelia. CFTR therapies may need to restore CFTR function to multiple cell types, with a focus on secretory cells.
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Affiliation(s)
- Kenichi Okuda
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | - Hong Dang
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | - Yoshihiko Kobayashi
- Department of Cell Biology, School of Medicine, Duke University, Durham, North Carolina
| | - Gianni Carraro
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
| | - Satoko Nakano
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | - Gang Chen
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | - Takafumi Kato
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | | | | | - Lisa C Morton
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | - Rhianna E Lee
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | | | - Wei-Ning Yin
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | | | | | | | - Michael Chua
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | | | | | - Carlton W Anderson
- Center for Gastrointestinal Biology and Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Andrew Ghio
- Clinical Research Branch, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Chapel Hill, North Carolina
| | - Hirotoshi Matsui
- Center for Respiratory Disease, National Hospital Organization Tokyo Hospital, Kiyose, Tokyo, Japan; and
| | - Takahide Nagase
- Department of Respiratory Medicine, The University of Tokyo, Tokyo, Japan
| | | | | | - John C Olsen
- Marsico Lung Institute/Cystic Fibrosis Research Center and
| | | | - Barry R Stripp
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
| | - Purushothama Rao Tata
- Department of Cell Biology, School of Medicine, Duke University, Durham, North Carolina
| | - Wanda K O'Neal
- Marsico Lung Institute/Cystic Fibrosis Research Center and
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Strandvik B. Is the ENaC Dysregulation in CF an Effect of Protein-Lipid Interaction in the Membranes? Int J Mol Sci 2021; 22:ijms22052739. [PMID: 33800499 PMCID: PMC7962953 DOI: 10.3390/ijms22052739] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/28/2021] [Accepted: 03/05/2021] [Indexed: 12/26/2022] Open
Abstract
While approximately 2000 mutations have been discovered in the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR), only a small amount (about 10%) is associated with clinical cystic fibrosis (CF) disease. The discovery of the association between CFTR and the hyperactive epithelial sodium channel (ENaC) has raised the question of the influence of ENaC on the clinical CF phenotype. ENaC disturbance contributes to the pathological secretion, and overexpression of one ENaC subunit, the β-unit, can give a CF-like phenotype in mice with normal acting CFTR. The development of ENaC channel modulators is now in progress. Both CFTR and ENaC are located in the cell membrane and are influenced by its lipid configuration. Recent studies have emphasized the importance of the interaction of lipids and these proteins in the membranes. Linoleic acid deficiency is the most prevailing lipid abnormality in CF, and linoleic acid is an important constituent of membranes. The influence on sodium excretion by linoleic acid supplementation indicates that lipid-protein interaction is of importance for the clinical pathophysiology in CF. Further studies of this association can imply a simple clinical adjuvant in CF therapy.
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Affiliation(s)
- Birgitta Strandvik
- Department of Biosciences and Nutrition, Karolinska Institutet NEO, 14183 Stockholm, Sweden
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3
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Hołyńska-Iwan I, Dziembowska I, Olszewska-Słonina D. The short-term rinsing of airways by N-acetylcysteine helps expectoration: The mechanism of sodium and chloride transport. POSTEP HIG MED DOSW 2020. [DOI: 10.5604/01.3001.0014.3831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
N-acetyl-L-cysteine (NAC) mucolytic and antioxidant role is well known, but the effect on epithelial ion transport has not been yet described. The aim of the study was to evaluate the short-term and prolonged influence of NAC on ion transport in the epithelium. The experiment was performed on 108 fragments of rabbit tracheae. Fragments were divided into four groups: inhibited sodium (I) and chloride (II) transport, NAC with inhibited sodium (III) and NAC with inhibited chloride (IV) transport. The changes in electrophysiological parameters were measured in stationary conditions and during mechanical-chemical stimulation after immediate (15 s) and prolonged (60 min) N-acetylcysteine administration on the tissue. Each 15-second stimulation caused repeatable changes in the electric potential of the tissue. In trachea fragments with blocked chloride ion transport, significantly lower (P <0.0001) values of electric potential following prolonged NAC effect were observed when compared to short-term NAC-stimulation. The values of resistance were constant during experiments, which reflects the vitality of the tissue. Short-term NAC administration influences sodium ion transport, which is not observed in a prolonged stimulation. The use of the NAC solution to rinse the airways is of great clinical importance due to the short and intense contact with the epithelium.
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Affiliation(s)
- Iga Hołyńska-Iwan
- Laboratory of Electrophysiology of Epithelial Tissue and Skin, Department of Pathobiochemistry and Clinical Chemistry, Faculty of Pharmacy, Ludwik Rydygier Collegium Medicum in Bydgoszcz Nicolaus Copernicus University in Torun
| | - Inga Dziembowska
- Department of Pathophysiology, Faculty of Pharmacy, Ludwik Rydygier Collegium Medicum in Bydgoszcz Nicolaus Copernicus University in Torun
| | - Dorota Olszewska-Słonina
- Department of Pathobiochemistry and Clinical Chemistry, Ludwik Rydygier Collegium Medicum in Bydgoszcz Nicolaus Copernicus University in Torun
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4
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Saint-Criq V, Gray MA. Role of CFTR in epithelial physiology. Cell Mol Life Sci 2016; 74:93-115. [PMID: 27714410 PMCID: PMC5209439 DOI: 10.1007/s00018-016-2391-y] [Citation(s) in RCA: 243] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 12/20/2022]
Abstract
Salt and fluid absorption and secretion are two processes that are fundamental to epithelial function and whole body fluid homeostasis, and as such are tightly regulated in epithelial tissues. The CFTR anion channel plays a major role in regulating both secretion and absorption in a diverse range of epithelial tissues, including the airways, the GI and reproductive tracts, sweat and salivary glands. It is not surprising then that defects in CFTR function are linked to disease, including life-threatening secretory diarrhoeas, such as cholera, as well as the inherited disease, cystic fibrosis (CF), one of the most common life-limiting genetic diseases in Caucasian populations. More recently, CFTR dysfunction has also been implicated in the pathogenesis of acute pancreatitis, chronic obstructive pulmonary disease (COPD), and the hyper-responsiveness in asthma, underscoring its fundamental role in whole body health and disease. CFTR regulates many mechanisms in epithelial physiology, such as maintaining epithelial surface hydration and regulating luminal pH. Indeed, recent studies have identified luminal pH as an important arbiter of epithelial barrier function and innate defence, particularly in the airways and GI tract. In this chapter, we will illustrate the different operational roles of CFTR in epithelial function by describing its characteristics in three different tissues: the airways, the pancreas, and the sweat gland.
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Affiliation(s)
- Vinciane Saint-Criq
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, University Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH UK
| | - Michael A. Gray
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, University Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH UK
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5
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Blackmon RL, Kreda SM, Sears PR, Ostrowski LE, Hill DB, Chapman BS, Tracy JB, Oldenburg AL. Diffusion-sensitive optical coherence tomography for real-time monitoring of mucus thinning treatments. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2016; 9697:969724. [PMID: 27746581 PMCID: PMC5061133 DOI: 10.1117/12.2208805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Mucus hydration (wt%) has become an increasingly useful metric in real-time assessment of respiratory health in diseases like cystic fibrosis and COPD, with higher wt% indicative of diseased states. However, available in vivo rheological techniques are lacking. Gold nanorods (GNRs) are attractive biological probes whose diffusion through tissue is sensitive to the correlation length of comprising biopolymers. Through employment of dynamic light scattering theory on OCT signals from GNRs, we find that weakly-constrained GNR diffusion predictably decreases with increasing wt% (more disease-like) mucus. Previously, we determined this method is robust against mucus transport on human bronchial epithelial (hBE) air-liquid interface cultures (R2=0.976). Here we introduce diffusion-sensitive OCT (DS-OCT), where we collect M-mode image ensembles, from which we derive depth- and temporally-resolved GNR diffusion rates. DS-OCT allows for real-time monitoring of changing GNR diffusion as a result of topically applied mucus-thinning agents, enabling monitoring of the dynamics of mucus hydration never before seen. Cultured human airway epithelial cells (Calu-3) with a layer of endogenous mucus were doped with topically deposited GNRs (80×22nm), and subsequently treated with hypertonic saline (HS) or isotonic saline (IS). DS-OCT provided imaging of the mucus thinning response up to a depth of 600μm with 4.65μm resolution, over a total of 8 minutes in increments of ≥3 seconds. For both IS and HS conditions, DS-OCT captured changes in the pattern of mucus hydration over time. DS-OCT opens a new window into understanding mechanisms of mucus thinning during treatment, enabling real-time efficacy feedback needed to optimize and tailor treatments for individual patients.
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Affiliation(s)
- Richard L Blackmon
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, NC 27599
| | - Silvia M Kreda
- Marsico Lung Institute/Cystic Fibrosis Research and Treatment Center, University of North Carolina at Chapel Hill, NC 27599
| | - Patrick R Sears
- Marsico Lung Institute/Cystic Fibrosis Research and Treatment Center, University of North Carolina at Chapel Hill, NC 27599
| | - Lawrence E Ostrowski
- Marsico Lung Institute/Cystic Fibrosis Research and Treatment Center, University of North Carolina at Chapel Hill, NC 27599
| | - David B Hill
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, NC 27599; Marsico Lung Institute/Cystic Fibrosis Research and Treatment Center, University of North Carolina at Chapel Hill, NC 27599
| | - Brian S Chapman
- Department of Material Science & Engineering, North Carolina State University, Raleigh, NC 27695
| | - Joseph B Tracy
- Department of Material Science & Engineering, North Carolina State University, Raleigh, NC 27695
| | - Amy L Oldenburg
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, NC 27599
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6
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Abstract
CFTR is a cAMP-activated chloride and bicarbonate channel that is critical for lung homeostasis. Decreases in CFTR expression have dire consequences in cystic fibrosis (CF) and have been suggested to be a component of the lung pathology in chronic obstructive pulmonary disease. Decreases or loss of channel function often lead to mucus stasis, chronic bacterial infections, and the accompanying chronic inflammatory responses that promote progressive lung destruction, and, eventually in CF, lung failure. Here we discuss CFTR's functional role airway surface liquid hydration and pH, in regulation of other channels such as the epithelial sodium channel, and in regulating inflammatory responses in the lung.
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Affiliation(s)
- James F Collawn
- Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; Pulmonary Injury and Repair Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and Gregory Fleming James Cystic Fibrosis Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Sadis Matalon
- Department of Anesthesiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; Pulmonary Injury and Repair Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and Gregory Fleming James Cystic Fibrosis Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
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Abstract
Ion channels perform a variety of cellular functions in lung epithelia. Oxidant- and antioxidant-mediated mechanisms (that is, redox regulation) of ion channels are areas of intense research. Significant progress has been made in our understanding of redox regulation of ion channels since the last Experimental Biology report in 2003. Advancements include: 1) identification of nonphagocytic NADPH oxidases as sources of regulated reactive species (RS) production in epithelia, 2) an understanding that excessive treatment with antioxidants can result in greater oxidative stress, and 3) characterization of novel RS signaling pathways that converge upon ion channel regulation. These advancements, as discussed at the 2013 Experimental Biology Meeting in Boston, MA, impact our understanding of oxidative stress in the lung, and, in particular, illustrate that the redox state has profound effects on ion channel and cellular function.
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Rab A, Rowe SM, Raju SV, Bebok Z, Matalon S, Collawn JF. Cigarette smoke and CFTR: implications in the pathogenesis of COPD. Am J Physiol Lung Cell Mol Physiol 2013; 305:L530-41. [PMID: 23934925 DOI: 10.1152/ajplung.00039.2013] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Chronic obstructive pulmonary disease (COPD) is a progressive respiratory disorder consisting of chronic bronchitis and/or emphysema. COPD patients suffer from chronic infections and display exaggerated inflammatory responses and a progressive decline in respiratory function. The respiratory symptoms of COPD are similar to those seen in cystic fibrosis (CF), although the molecular basis of the two disorders differs. CF is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene encoding a chloride and bicarbonate channel (CFTR), leading to CFTR dysfunction. The majority of COPD cases result from chronic oxidative insults such as cigarette smoke. Interestingly, environmental stresses including cigarette smoke, hypoxia, and chronic inflammation have also been implicated in reduced CFTR function, and this suggests a common mechanism that may contribute to both the CF and COPD. Therefore, improving CFTR function may offer an excellent opportunity for the development of a common treatment for CF and COPD. In this article, we review what is known about the CF respiratory phenotype and discuss how diminished CFTR expression-associated ion transport defects may contribute to some of the pathological changes seen in COPD.
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Affiliation(s)
- Andras Rab
- Dept. of Cell, Developmental and Integrative Biology, Univ. of Alabama at Birmingham, 1918 Univ. Blvd., MCLM 395, Birmingham, AL 35294.
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Hobbs CA, Da Tan C, Tarran R. Does epithelial sodium channel hyperactivity contribute to cystic fibrosis lung disease? J Physiol 2013; 591:4377-87. [PMID: 23878362 DOI: 10.1113/jphysiol.2012.240861] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Airway epithelia absorb Na+ through the epithelial Na+ channel (ENaC) and secrete Cl- through the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. This balance maintains sufficient airway surface liquid hydration to permit efficient mucus clearance, which is needed to maintain sterility of the lung. Cystic fibrosis (CF) is a common autosomal recessive inherited disease caused by mutations in the CFTR gene that lead to the reduction or elimination of the CFTR protein. CF is a multi-organ disease that affects epithelia lining the intestines, lungs, pancreas, sweat ducts and vas deferens, among others. CF lungs are characterized by viscous, dehydrated mucus, persistent neutrophilia and chronic infections. ENaC is negatively regulated by CFTR and, in patients with CF, the absence of CFTR results in a double hit of reduced Cl-/HCO3- and H2O secretion as well as ENaC hyperactivity and increased Na+ and H2O absorption. Together, these effects are hypothesized to trigger mucus dehydration, resulting in a failure to clear mucus. Rehydrating CF mucus has become a recent clinical focus and yields important end-points for clinical trials. However, while ENaC hyperactivity in CF airways has been detected in vivo and in vitro, recent data have brought the role of ENaC in CF lung disease pathogenesis into question. This review will focus on our current understanding of the contribution of ENaC to CF pathogenesis.
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Affiliation(s)
- Carey A Hobbs
- R. Tarran: 7125 Thurston Bowles Building, UNC, Chapel Hill, NC 27599-7248, USA.
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10
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Vohwinkel CU, Vadász I. Influenza A matrix protein M2 downregulates CFTR: inhibition of chloride transport by a proton channel of the viral envelope. Am J Physiol Lung Cell Mol Physiol 2013; 304:L813-6. [PMID: 23605001 DOI: 10.1152/ajplung.00091.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Livraghi-Butrico A, Kelly EJ, Wilkinson KJ, Rogers TD, Gilmore RC, Harkema JR, Randell SH, Boucher RC, O'Neal WK, Grubb BR. Loss of Cftr function exacerbates the phenotype of Na(+) hyperabsorption in murine airways. Am J Physiol Lung Cell Mol Physiol 2013; 304:L469-80. [PMID: 23377346 DOI: 10.1152/ajplung.00150.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway surface hydration depends on the balance between transepithelial Na(+) absorption and Cl(-) secretion. In adult mice, absence of functional cystic fibrosis transmembrane conductance regulator (Cftr) fails to recapitulate human cystic fibrosis (CF) lung disease. In contrast, overexpression of the epithelial Na(+) channel β subunit in transgenic mice (βENaC-Tg) produces unregulated Na(+) hyperabsorption and results in CF-like airway surface dehydration, mucus obstruction, inflammation, and increased neonatal mortality. To investigate whether the combination of airway Na(+) hyperabsorption and absent Cftr-mediated Cl(-) secretion resulted in more severe lung pathology, we generated double-mutant ΔF508 CF/βENaC-Tg mice. Survival of ΔF508 CF/βENaC-Tg mice was reduced compared with βENaC-Tg or ΔF508 CF mice. Absence of functional Cftr did not affect endogenous or transgenic ENaC currents but produced reduced basal components of Cl(-) secretion and tracheal cartilaginous defects in both ΔF508 CF and ΔF508 CF/βENaC-Tg mice. Neonatal ΔF508 CF/βENaC-Tg mice exhibited higher neutrophilic pulmonary inflammation and club cell (Clara cell) necrosis compared with βENaC-Tg littermates. Neonatal ΔF508 CF/βENaC-Tg mice also exhibited spontaneous bacterial infections, but the bacterial burden was similar to that of βENaC-Tg littermates. Adult ΔF508 CF/βENaC-Tg mice exhibited pathological changes associated with eosinophilic crystalline pneumonia, a phenotype not observed in age-matched βENaC-Tg mice. Collectively, these data suggest that the combined abnormalities in Na(+) absorption and Cl(-) secretion produce more severe lung disease than either defect alone. Airway cartilage abnormalities, airway cell necrosis, and exaggerated neutrophil infiltration likely interact with defective mucus clearance caused by βENaC overexpression and absent CFTR-mediated Cl(-) secretion to produce the increased neonatal mortality observed in ΔF508 CF/βENaC-Tg mice.
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Affiliation(s)
- Alessandra Livraghi-Butrico
- Cystic Fibrosis/Pulmonary Research and Treatment Center, School of Medicine, The University of North Carolina at Chapel Hill, 6029 Thurston Bowles Bldg., Chapel Hill, NC 25799-7248, USA.
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12
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Reddy MM, Stutts MJ. Status of fluid and electrolyte absorption in cystic fibrosis. Cold Spring Harb Perspect Med 2013; 3:a009555. [PMID: 23284077 DOI: 10.1101/cshperspect.a009555] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Salt and fluid absorption is a shared function of many of the body's epithelia, but its use is highly adapted to the varied physiological roles of epithelia-lined organs. These functions vary from control of hydration of outward-facing epithelial surfaces to conservation and regulation of total body volume. In the most general context, salt and fluid absorption is driven by active Na(+) absorption. Cl(-) is absorbed passively through various available paths in response to the electrical driving force that results from active Na(+) absorption. Absorption of salt creates a concentration gradient that causes water to be absorbed passively, provided the epithelium is water permeable. Key differences notwithstanding, the transport elements used for salt and fluid absorption are broadly similar in diverse epithelia, but the regulation of these elements enables salt absorption to be tailored to very different physiological needs. Here we focus on salt absorption by exocrine glands and airway epithelia. In cystic fibrosis, salt and fluid absorption by gland duct epithelia is effectively prevented by the loss of cystic fibrosis transmembrane conductance regulator (CFTR). In airway epithelia, salt and fluid absorption persists, in the absence of CFTR-mediated Cl(-) secretion. The contrast of these tissue-specific changes in CF tissues is illustrative of how salt and fluid absorption is differentially regulated to accomplish tissue-specific physiological objectives.
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Affiliation(s)
- M M Reddy
- Department of Pediatrics, UCSD School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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13
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Johannesson B, Hirtz S, Schatterny J, Schultz C, Mall MA. CFTR regulates early pathogenesis of chronic obstructive lung disease in βENaC-overexpressing mice. PLoS One 2012; 7:e44059. [PMID: 22937152 PMCID: PMC3427321 DOI: 10.1371/journal.pone.0044059] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 07/30/2012] [Indexed: 11/23/2022] Open
Abstract
Background Factors determining the onset and severity of chronic obstructive pulmonary disease remain poorly understood. Previous studies demonstrated that airway surface dehydration in βENaC-overexpressing (βENaC-Tg) mice on a mixed genetic background caused either neonatal mortality or chronic obstructive lung disease suggesting that the onset of lung disease was modulated by the genetic background. Methods To test this hypothesis, we backcrossed βENaC-Tg mice onto two inbred strains (C57BL/6 and BALB/c) and studied effects of the genetic background on neonatal mortality, airway ion transport and airway morphology. Further, we crossed βENaC-Tg mice with CFTR-deficient mice to validate the role of CFTR in early lung disease. Results We demonstrate that the C57BL/6 background conferred increased CFTR-mediated Cl− secretion, which was associated with decreased mucus plugging and mortality in neonatal βENaC-Tg C57BL/6 compared to βENaC-Tg BALB/c mice. Conversely, genetic deletion of CFTR increased early mucus obstruction and mortality in βENaC-Tg mice. Conclusions We conclude that a decrease or absence of CFTR function in airway epithelia aggravates the severity of early airway mucus obstruction and related mortality in βENaC-Tg mice. These results suggest that genetic or environmental factors that reduce CFTR activity may contribute to the onset and severity of chronic obstructive pulmonary disease and that CFTR may serve as a novel therapeutic target.
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Affiliation(s)
- Bjarki Johannesson
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research, University of Heidelberg, Heidelberg, Germany
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Molecular Medicine Partnership Unit, University of Heidelberg and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Stephanie Hirtz
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research, University of Heidelberg, Heidelberg, Germany
| | - Jolanthe Schatterny
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research, University of Heidelberg, Heidelberg, Germany
| | - Carsten Schultz
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research, University of Heidelberg, Heidelberg, Germany
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Molecular Medicine Partnership Unit, University of Heidelberg and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Marcus A. Mall
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research, University of Heidelberg, Heidelberg, Germany
- Division of Pediatric Pulmonology and Allergy and Cystic Fibrosis Center, Department of Pediatrics III, University of Heidelberg, Heidelberg, Germany
- Molecular Medicine Partnership Unit, University of Heidelberg and European Molecular Biology Laboratory, Heidelberg, Germany
- * E-mail:
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14
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Collawn JF, Lazrak A, Bebok Z, Matalon S. The CFTR and ENaC debate: how important is ENaC in CF lung disease? Am J Physiol Lung Cell Mol Physiol 2012; 302:L1141-6. [PMID: 22492740 PMCID: PMC3379041 DOI: 10.1152/ajplung.00036.2012] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 04/02/2012] [Indexed: 01/07/2023] Open
Abstract
Cystic fibrosis (CF) is caused by the loss of the cystic fibrosis transmembrane conductance regulator (CFTR) function and results in a respiratory phenotype that is characterized by dehydrated mucus and bacterial infections that affect CF patients throughout their lives. Much of the morbidity and mortality in CF results from a failure to clear bacteria from the lungs. What causes the defect in the bacterial clearance in the CF lung has been the subject of an ongoing debate. Here we discuss the arguments for and against the role of the epithelial sodium channel, ENaC, in the development of CF lung disease.
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Affiliation(s)
- James F Collawn
- Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, 35294-0005, USA.
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