title: Endosomal hyperacidification in cystic fibrosis is due to defective nitric oxide-cylic GMP signalling cascade.
abstract: Endosomal hyperacidification in cystic fibrosis (CF) respiratory epithelial cells is secondary to a loss of sodium transport control owing to a defective form of the CF transmembrane conductance regulator CFTR. Here, we show that endosomal hyperacidification can be corrected by activating the signalling cascade controlling sodium channels through cyclic GMP. Nitric oxide (NO) donors corrected the endosomal hyperacidification in CF cells. Stimulation of CF cells with guanylate cyclase agonists corrected the pH in endosomes. Exposure of CF cells to an inhibitor of cGMP-specific phosphodiesterase PDE5, Sildenafil, normalized the endosomal pH. Treatment with Sildenafil reduced secretion by CF cells of the proinflammatory chemokine interleukin 8 following stimulation with Pseudomonas aeruginosa products. Thus, the endosomal hyperacidification and excessive proinflammatory response in CF are in part due to deficiencies in NO- and cGMP-regulated processes and can be pharmacologically reversed using PDE5 inhibitors.
authors.affiliation: Department of Molecular Genetics & Microbiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico, 87131, USA.
authors.forename: Jens F
authors.initials: JF
authors.lastname: Poschet
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Fazio
authors.forename: Graham S
authors.initials: GS
authors.lastname: Timmins
authors.forename: Wojciech
authors.initials: W
authors.lastname: Ornatowski
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Perkett
authors.forename: Monica
authors.initials: M
authors.lastname: Delgado
authors.forename: Vojo
authors.initials: V
authors.lastname: Deretic
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000172:deficiency* / Q000502:physiology; D003550:Cystic Fibrosis / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D011992:Endosomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D009569:Nitric Oxide / Q000172:deficiency* / Q000502:physiology; D010879:Piperazines / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D020545:Respiratory Mucosa / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D009569:Nitric Oxide; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D006152:Cyclic GMP