title: AMPK agonists ameliorate sodium and fluid transport and inflammation in cystic fibrosis airway epithelial cells.
abstract: The metabolic sensor AMP-activated kinase (AMPK) inhibits both the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) Cl(-) channel and epithelial Na(+) channel (ENaC), and may inhibit secretion of proinflammatory cytokines in epithelia. Here we have tested in primary polarized CF and non-CF human bronchial epithelial (HBE) cells the effects of AMPK activators, metformin and 5-aminoimidazole-4-carboxamide-1-beta-D-riboside (AICAR), on various parameters that contribute to CF lung disease: ENaC-dependent short-circuit currents (I(sc)), airway surface liquid (ASL) height, and proinflammatory cytokine secretion. AMPK activation after overnight treatment with either metformin (2-5 mM) or AICAR (1 mM) substantially inhibited ENaC-dependent I(sc) in both CF and non-CF airway cultures. Live-cell confocal images acquired 60 minutes after apical addition of Texas Red-dextran-containing fluid revealed significantly greater ASL heights after AICAR and metformin treatment relative to controls, suggesting that AMPK-dependent ENaC inhibition slows apical fluid reabsorption. Both metformin and AICAR decreased secretion of various proinflammatory cytokines, both with and without prior LPS stimulation. Finally, prolonged exposure to more physiologically relevant concentrations of metformin (0.03-1 mM) inhibited ENaC currents and decreased proinflammatory cytokine levels in CF HBE cells in a dose-dependent manner. These findings suggest that novel therapies to activate AMPK in the CF airway may be beneficial by blunting excessive sodium and ASL absorption and by reducing excessive airway inflammation, which are major contributors to CF lung disease.
authors.affiliation: Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, S976 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Myerburg
authors.forename: J Darwin
authors.initials: JD
authors.lastname: King
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Oyster
authors.forename: Adam C
authors.initials: AC
authors.lastname: Fitch
authors.forename: Amy
authors.initials: A
authors.lastname: Magill
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Baty
authors.forename: Simon C
authors.initials: SC
authors.lastname: Watkins
authors.forename: Jay K
authors.initials: JK
authors.lastname: Kolls
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Pilewski
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Hallows
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D016764:Cell Polarity; D002478:Cells, Cultured; D003550:Cystic Fibrosis / Q000201:enzymology* / Q000276:immunology / Q000503:physiopathology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology; D053503:Epithelial Sodium Channels / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D008564:Membrane Potentials; D008687:Metformin / Q000494:pharmacology; D018613:Microscopy, Confocal; D011014:Pneumonia / Q000201:enzymology* / Q000276:immunology / Q000503:physiopathology; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology / Q000503:physiopathology; D012265:Ribonucleotides / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D013997:Time Factors; D014882:Water-Electrolyte Balance / Q000187:drug effects*
chemical_list: D000893:Anti-Inflammatory Agents; C505032:CFTR protein, human; D016207:Cytokines; D020536:Enzyme Activators; D053503:Epithelial Sodium Channels; D018836:Inflammation Mediators; D012265:Ribonucleotides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000620:Aminoimidazole Carboxamide; D008687:Metformin; D012964:Sodium; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide