title: Effects of amphotericin B on ion transport proteins in airway epithelial cells.
abstract: Topical intranasal application of the antifungal Amphotericin B (AmphoB) has been shown as an effective medical treatment of chronic rhinosinusitis. Because this antibiotic forms channels in lipid membranes, we considered the possibility that it affects the properties and/or cell surface expression of ion channels/pumps, and consequently transepithelial ion transport. Human nasal epithelial cells were exposed apically to AmphoB (50 microM) for 4 h, 5 days (4 h daily), and 4 weeks (4 h daily, 5 days weekly) and allowed to recover for 18-48 h. AmphoB significantly reduced transepithelial potential difference, short-circuit current, and the amiloride-sensitive current. This was not due to generalized cellular toxicity as judged from normal transepithelial resistance and mitochondrial activity, but was related to inhibitory effects of AmphoB on ion transport proteins. Thus, cells exposed to AmphoB for 4 h showed decreased apical epithelial sodium channels (ENaC) activity with no change in basolateral Na(+)K(+)-ATPase activity and K(+) conductance, and reduced amount of alphaENaC, alpha1-Na(+)K(+)-ATPase, and NKCC1 proteins at the cell membrane, but no change in mRNA levels. After a 5-day treatment, there was a significant decrease in Na(+)K(+)-ATPase activity. After a 4-week treatment, a decrease in basolateral K(+) conductance and in alphaENaC and alpha1-Na(+)K(+)-ATPase mRNA levels was also observed. These findings may reflect a feedback mechanism aimed to limit cellular Na(+) overload and K(+) depletion subsequently to formation of AmphoB pores in the cell membrane. Thus, the decreased Na(+) absorption induced by AmphoB resulted from reduced cell surface expression of the ENaC, Na(+)K(+)-ATPase pump and NKCC1 and not from direct inhibition of their activities.
authors.affiliation: Respiratory Division, Department of Internal Medicine, University Hospitals, Geneva, Switzerland. Lan.H.Jornot@hcuge.ch
authors.forename: Lan
authors.initials: L
authors.lastname: Jornot
authors.forename: Thierry
authors.initials: T
authors.lastname: Rochat
authors.forename: Assunta
authors.initials: A
authors.lastname: Caruso
authors.forename: Jean-Silvain
authors.initials: JS
authors.lastname: Lacroix
mesh_terms: D000666:Amphotericin B / Q000494:pharmacology* / Q000633:toxicity; D021941:Caveolae / Q000187:drug effects / Q000378:metabolism; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism; D002478:Cells, Cultured; D003902:Detergents / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism*; D053503:Epithelial Sodium Channels; D006801:Humans; D017136:Ion Transport / Q000187:drug effects; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009297:Nasal Mucosa / Q000166:cytology*; D062793:Occludin; D010766:Phosphorylation / Q000187:drug effects; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters / Q000235:genetics / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism; D012995:Solubility / Q000187:drug effects; D064506:Solute Carrier Family 12, Member 2
chemical_list: D051242:Caveolin 1; D022461:Caveolins; D003902:Detergents; D053503:Epithelial Sodium Channels; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D021122:Protein Subunits; D012333:RNA, Messenger; C578877:SLC12A2 protein, human; D015222:Sodium Channels; D028021:Sodium-Potassium-Chloride Symporters; D064506:Solute Carrier Family 12, Member 2; D000666:Amphotericin B; D000254:Sodium-Potassium-Exchanging ATPase