title: Dynamic activation of cystic fibrosis transmembrane conductance regulator by type 3 and type 4D phosphodiesterase inhibitors.
abstract: The diseases of cystic fibrosis, chronic obstructive pulmonary disease (COPD), and chronic bronchitis are characterized by mucus-congested and inflamed airways. Anti-inflammatory agents that can simultaneously restore or enhance mucociliary clearance through cystic fibrosis transmembrane conductance regulator (CFTR) activation may represent new therapeutics in their treatment. Herein, we report the activation of CFTR-mediated chloride secretion by phosphodiesterase (PDE) 4 inhibitors in T84 monolayer using (125)I anion as tracer. In the absence of forskolin, the iodide secretion was insensitive to PDE4 inhibitor L-826,141 [4-[2-(3,4-bis-difluoromethoxyphenyl)-2-[4-(1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)phenyl]-ethyl]-3-methylpyridine-1-oxide], roflumilast, or to PDE3 inhibitor trequinsin. However, these inhibitors potently augmented iodide secretion after forskolin stimulation, with efficacy coupled to the activation states of adenylyl cyclase. The iodide secretion from PDE3 or PDE4 inhibition was characterized at first by a prolonged efflux duration, followed by progressively elevated peak efflux rates at higher inhibitor concentrations. Paralleled with an increased phosphor-cAMP response element-binding protein formation, the CFTR activation dissociated from a global cAMP elevation and was blocked by H89 [N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide]. 2-(4-Fluorophenoxy)-N-[(1S)-1-(4-methoxyphenyl)ethyl]nicotinamide, a stereoselective PDE4D inhibitor, augmented iodide efflux more efficiently than its less potent (R)-isomer. The peak efflux from maximal PDE4 and PDE3 inhibition matched that from full adenylyl cyclase activation. These data suggest that PDE3 and PDE4 (mainly PDE4D) form the major cAMP diffusion barrier in T84 cells to ensure a compartmentalized CFTR signaling. Together with their potent anti-inflammatory properties, the potentially enhanced airway mucociliary clearance from CFTR activation may have contributed to the efficacy of PDE4 inhibitors in COPD and asthmatic patients. PDE4 inhibitors may represent new opportunities to combat cystic fibrosis and other respiratory diseases in future.
authors.affiliation: Merck Frosst Center for Therapeutic Research, P.O. Box 1005, Pointe Claire-Dorval, Quebec H9R 4P8, Canada.
authors.forename: Susana
authors.initials: S
authors.lastname: Liu
authors.forename: Alain
authors.initials: A
authors.lastname: Veilleux
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Andrew
authors.initials: A
authors.lastname: Young
authors.forename: Evonne
authors.initials: E
authors.lastname: Kwok
authors.forename: France
authors.initials: F
authors.lastname: Laliberté
authors.forename: Christine
authors.initials: C
authors.lastname: Chung
authors.forename: Michael R
authors.initials: MR
authors.lastname: Tota
authors.forename: Daniel
authors.initials: D
authors.lastname: Dubé
authors.forename: Richard W
authors.initials: RW
authors.lastname: Friesen
authors.forename: Zheng
authors.initials: Z
authors.lastname: Huang
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000631:Aminopyridines / Q000494:pharmacology; D001549:Benzamides / Q000494:pharmacology; D001711:Biotransformation / Q000187:drug effects; D015153:Blotting, Western; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D003521:Cyclopropanes / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007457:Iodine Radioisotopes; D007546:Isoquinolines / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D000631:Aminopyridines; D001549:Benzamides; C505032:CFTR protein, human; D002712:Chlorides; D003521:Cyclopropanes; D007457:Iodine Radioisotopes; D007546:Isoquinolines; D010726:Phosphodiesterase Inhibitors; D013449:Sulfonamides; C424423:Roflumilast; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; C517376:PDE4D protein, human; D000262:Adenylyl Cyclases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide