Liquid secretion inhibitors reduce mucociliary transport in glandular airways

2002 ◽  
Vol 283 (2) ◽  
pp. L329-L335 ◽  
Author(s):  
Stephen T. Ballard ◽  
Laura Trout ◽  
Anil Mehta ◽  
Sarah K. Inglis
Keyword(s):  
Beat Frequency ◽  
Anion Channel ◽  
Ciliary Beat Frequency ◽  
Mucociliary Transport ◽  
Transmembrane Conductance Regulator ◽  
Inhibitory Effects ◽  
Transmembrane Conductance ◽  
Regulator Protein ◽  
Liquid Absorption ◽  
Cf Transmembrane Conductance Regulator

Because of its possible importance in cystic fibrosis (CF) pulmonary pathogenesis, the effect of anion and liquid secretion inhibitors on airway mucociliary transport was examined. When excised porcine tracheas were treated with ACh to induce gland liquid secretion, the rate of mucociliary transport was increased nearly threefold from 2.5 ± 0.5 to 6.8 ± 0.8 mm/min. Pretreatment with both bumetanide and dimethylamiloride (DMA), to respectively inhibit Cl− and HCO[Formula: see text]secretion, significantly reduced mucociliary transport in the presence of ACh by 92%. Pretreatment with the anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid similarly reduced mucociliary transport in ACh-treated airways by 97%. These agents did not, however, reduce ciliary beat frequency. Luminal application of benzamil to block liquid absorption significantly attenuated the inhibitory effects of bumetanide and DMA on mucociliary transport. We conclude that anion and liquid secretion is essential for normal mucociliary transport in glandular airways. Because the CF transmembrane conductance regulator protein likely mediates Cl−, HCO[Formula: see text], and liquid secretion in normal glands, we speculate that impairment of gland liquid secretion significantly contributes to defective mucociliary transport in CF.

scholarly journals VX-809 corrects folding defects in cystic fibrosis transmembrane conductance regulator protein through action on membrane-spanning domain 1

2013 ◽  
Vol 24 (19) ◽  
pp. 3016-3024 ◽  
Author(s):  
Hong Yu Ren ◽  
Diane E. Grove ◽  
Oxana De La Rosa ◽  
Scott A. Houck ◽  
Pattarawut Sopha ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Chloride Transport ◽  
Genetic Disorder ◽  
Missense Mutations ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Regulator Protein ◽  
Folding Defect ◽  
Membrane Spanning ◽  
Cf Transmembrane Conductance Regulator

Cystic fibrosis (CF) is a fatal genetic disorder associated with defective hydration of lung airways due to the loss of chloride transport through the CF transmembrane conductance regulator protein (CFTR). CFTR contains two membrane-spanning domains (MSDs), two nucleotide-binding domains (NBDs), and a regulatory domain, and its channel assembly requires multiple interdomain contacts. The most common CF-causing mutation, F508del, occurs in NBD1 and results in misfolding and premature degradation of F508del-CFTR. VX-809 is an investigational CFTR corrector that partially restores CFTR function in people who are homozygous for F508del-CFTR. To identify the folding defect(s) in F508del-CFTR that must be repaired to treat CF, we explored the mechanism of VX-809 action. VX-809 stabilized an N-terminal domain in CFTR that contains only MSD1 and efficaciously restored function to CFTR forms that have missense mutations in MSD1. The action of VX-809 on MSD1 appears to suppress folding defects in F508del-CFTR by enhancing interactions among the NBD1, MSD1, and MSD2 domains. The ability of VX-809 to correct F508del-CFTR is enhanced when combined with mutations that improve F508del-NBD1 interaction with MSD2. These data suggest that the use of VX-809 in combination with an additional CFTR corrector that suppresses folding defects downstream of MSD1 may further enhance CFTR function in people with F508del-CFTR.

scholarly journals Mechanism of substance P-induced liquid secretion across bronchial epithelium

2001 ◽  
Vol 281 (3) ◽  
pp. L639-L645 ◽  
Author(s):  
Laura Trout ◽  
Michel R. Corboz ◽  
Stephen T. Ballard
Keyword(s):  
Substance P ◽  
Anion Channel ◽  
Bronchial Epithelium ◽  
Surface Epithelium ◽  
Channel Blockers ◽  
Transmembrane Conductance Regulator ◽  
Inhibitory Effects ◽  
Transmembrane Conductance ◽  
Submucosal Glands ◽  
Cystic Fibrosis Transmembrane

The present study was undertaken to identify and determine the mechanism of noncholinergic pathways for the induction of liquid secretion across airway epithelium. Excised porcine bronchi secreted substantial and significant quantities of liquid when exposed to acetylcholine, substance P, or forskolin but not to isoproterenol, norepinephrine, or phenylephrine. Bumetanide, an inhibitor of Na+-K+-2Cl− cotransport, reduced the liquid secretion response to substance P by 69%. Approximately two-thirds of bumetanide-insensitive liquid secretion was blocked by dimethylamiloride (DMA), a Na+/H+ exchange inhibitor. Substance P responses were preserved in airways after surface epithelium removal, suggesting that secreted liquid originated from submucosal glands. The anion channel blockers diphenylamine-2-carboxylate (DPC) and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) inhibited >90% of substance P-induced liquid secretion, whereas DIDS had no effect. DMA, DPC, and NPPB had greater inhibitory effects on net HCO[Formula: see text] secretion than on liquid secretion. Although preserved relative to liquid secretion, net HCO[Formula: see text]secretion was reduced by 39% in the presence of bumetanide. We conclude that substance P induces liquid secretion from bronchial submucosal glands of pigs through active transport of Cl−and HCO[Formula: see text]. The pattern of responses to secretion agonists and antagonists suggests that the cystic fibrosis transmembrane conductance regulator mediates this process.

Chloride conductance of CFTR facilitates basal Cl−/HCO3−exchange in the villous epithelium of intact murine duodenum

2005 ◽  
Vol 288 (6) ◽  
pp. G1241-G1251 ◽  
Author(s):  
Janet E. Simpson ◽  
Lara R. Gawenis ◽  
Nancy M. Walker ◽  
Kathryn T. Boyle ◽  
Lane L. Clarke
Keyword(s):  
Exchange Rate ◽  
Apical Membrane ◽  
Anion Channel ◽  
Duodenal Mucosa ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Anion Exchanger 1 ◽  
Direct Exposure ◽  
Mucus Barrier ◽  
Cf Transmembrane Conductance Regulator

Villi of the proximal duodenum are situated for direct exposure to gastric acid chyme. However, little is known about active bicarbonate secretion across villi that maintains the protective alkaline mucus barrier, a process that may be compromised in cystic fibrosis (CF), i.e., in the absence of a functional CF transmembrane conductance regulator (CFTR) anion channel. We investigated Cl−/HCO3−exchange activity across the apical membrane of epithelial cells located at the midregion of villi in intact duodenal mucosa from wild-type (WT) and CF mice using the pH-sensitive dye BCECF. Under basal conditions, the Cl−/HCO3−exchange rate was reduced by ∼35% in CF compared with WT villous epithelium. Cl−/HCO3−exchange in WT and CF villi responded similarly to inhibitors of anion exchange, and membrane depolarization enhanced rates of Cl−out/HCO3−inexchange in both epithelia. In anion substitution studies, anionin/HCO3−outexchange rates were greater in WT epithelium using Cl−or NO3−, but decreased to the level of the CF epithelium using the CFTR-impermeant anion, SO42−. Similarly, treatment of WT epithelium with the CFTR-selective blocker glybenclamide decreased the Cl−/HCO3−exchange rate to the level of CF epithelium. The mRNA expression of Slc26a3 (downregulated in adenoma) and Slc26a6 (putative anion exchanger-1) was similar between WT and CF duodena. From these studies of murine duodenum, we conclude 1) characteristics of Cl−/HCO3−exchange in the villous epithelium are most consistent with Slc26a6 activity, and 2) Cl−channel activity of CFTR facilitates apical membrane Cl−in/HCO3−outexchange by providing a Cl−“leak” under basal conditions.

scholarly journals Postnatal airway growth in cystic fibrosis piglets

2017 ◽  
Vol 123 (3) ◽  
pp. 526-533 ◽  
Author(s):  
Ryan J. Adam ◽  
Mahmoud H. Abou Alaiwa ◽  
Drake C. Bouzek ◽  
Daniel P. Cook ◽  
Nicholas D. Gansemer ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Lung Disease ◽  
Lung Volume ◽  
Growth And Development ◽  
Anion Channel ◽  
Postnatal Period ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Disease Pathogenesis ◽  
Cf Transmembrane Conductance Regulator

Mutations in the gene encoding the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) anion channel cause CF. The leading cause of death in the CF population is lung disease. Increasing evidence suggests that in utero airway development is CFTR-dependent and that developmental abnormalities may contribute to CF lung disease. However, relatively little is known about postnatal CF airway growth, largely because such studies are limited in humans. Therefore, we examined airway growth and lung volume in a porcine model of CF. We hypothesized that CF pigs would have abnormal postnatal airway growth. To test this hypothesis, we performed CT-based airway and lung volume measurements in 3-wk-old non-CF and CF pigs. We found that 3-wk-old CF pigs had tracheas of reduced caliber and irregular shape. Their bronchial lumens were reduced in size proximally but not distally, were irregularly shaped, and had reduced distensibility. Our data suggest that lack of CFTR results in aberrant postnatal airway growth and development, which could contribute to CF lung disease pathogenesis. NEW & NOTEWORTHY This CT scan-based study of airway morphometry in the cystic fibrosis (CF) postnatal period is unique, as analogous studies in humans are greatly limited for ethical and technical reasons. Findings such as reduced airway lumen area and irregular caliber suggest that airway growth and development are CF transmembrane conductance regulator-dependent and that airway growth defects may contribute to CF lung disease pathogenesis.

scholarly journals Rescuing ΔF508 CFTR with trimethylangelicin, a dual-acting corrector and potentiator

2014 ◽  
Vol 307 (6) ◽  
pp. L431-L434 ◽  
Author(s):  
James F. Collawn ◽  
Lianwu Fu ◽  
Rafal Bartoszewski ◽  
Sadis Matalon
Keyword(s):  
Anion Channel ◽  
Transmembrane Conductance Regulator ◽  
Nucleotide Binding Domain ◽  
Transmembrane Conductance ◽  
Surface Stability ◽  
Molecular Defects ◽  
Δf508 Cftr ◽  
Cftr Protein ◽  
Cf Transmembrane Conductance Regulator ◽  
Phenylalanine Residue

Since the discovery of the cystic fibrosis (CF) gene that encodes the CF transmembrane conductance regulator (CFTR) in 1989, there has been considerable progress in understanding the molecular defects associated with different mutations in the CFTR protein. Small molecule “potentiators” have led the way as a drug therapeutic approach for correcting channel gating mutations such as the G551D mutation. Therapies for correcting the most common folding mutation in CFTR, ΔF508, however, have proven to be much more challenging. The protein-folding problem appears to be associated with both nucleotide binding domain (NBD) instability and domain interface interactions that are caused by the loss of the phenylalanine residue in NBD 1. Given the inherent complexity in the sequential folding pathway for this very large multidomain protein, it has been suggested that correcting the proper folding, anion channel function, and cell surface stability of the ΔF508 CFTR protein will require a multidrug approach to fix each of these compounding problems. Here we discuss a recent publication (Favia M, Mancini MT, Bezzerri V, Guerra L, Laselva O, Abbattiscianni AC, Debellis L, Reshkin SJ, Gambari R, Cabrini G, Casavola V. Am J Physiol Lung Cell Mol Physiol 307: L48–L61, 2014), however, that offers hope that single drug therapies are still possible.

scholarly journals Metaproteomics to Decipher CF Host-Microbiota Interactions: Overview, Challenges and Future Perspectives

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 892
Author(s):  
Pauline Hardouin ◽  
Raphael Chiron ◽  
Hélène Marchandin ◽  
Jean Armengaud ◽  
Lucia Grenga
Keyword(s):  
Cystic Fibrosis ◽  
Treatment Outcome ◽  
Chronic Infection ◽  
Phenotypic Variability ◽  
Anion Channel ◽  
Hereditary Disease ◽  
Transmembrane Conductance Regulator ◽  
Future Perspectives ◽  
Transmembrane Conductance ◽  
Cf Transmembrane Conductance Regulator

Cystic fibrosis (CF) is a hereditary disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, triggering dysfunction of the anion channel in several organs including the lung and gut. The main cause of morbidity and mortality is chronic infection. The microbiota is now included among the additional factors that could contribute to the exacerbation of patient symptoms, to treatment outcome, and more generally to the phenotypic variability observed in CF patients. In recent years, various omics tools have started to shed new light on microbial communities associated with CF and host–microbiota interactions. In this context, proteomics targets the key effectors of the responses from organisms, and thus their phenotypes. Recent advances are promising in terms of gaining insights into the CF microbiota and its relation with the host. This review provides an overview of the contributions made by proteomics and metaproteomics to our knowledge of the complex host–microbiota partnership in CF. Considering the strengths and weaknesses of proteomics-based approaches in profiling the microbiota in the context of other diseases, we illustrate their potential and discuss possible strategies to overcome their limitations in monitoring both the respiratory and intestinal microbiota in sample from patients with CF.

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