title: Proinflammatory mediators disrupt glucose homeostasis in airway surface liquid.
abstract: The glucose concentration of the airway surface liquid (ASL) is much lower than that in blood and is tightly regulated by the airway epithelium. ASL glucose is elevated in patients with viral colds, cystic fibrosis, chronic obstructive pulmonary disease, and asthma. Elevated ASL glucose is also associated with increased incidence of respiratory infection. However, the mechanism by which ASL glucose increases under inflammatory conditions is unknown. The aim of this study was to investigate the effect of proinflammatory mediators (PIMs) on the mechanisms governing airway glucose homeostasis in polarized monolayers of human airway (H441) and primary human bronchial epithelial (HBE) cells. Monolayers were treated with TNF-α, IFN-γ, and LPS during 72 h. PIM treatment led to increase in ASL glucose concentration and significantly reduced H441 and HBE transepithelial resistance. This decline in transepithelial resistance was associated with an increase in paracellular permeability of glucose. Similar enhanced rates of paracellular glucose flux were also observed across excised trachea from LPS-treated mice. Interestingly, PIMs enhanced glucose uptake across the apical, but not the basolateral, membrane of H441 and HBE monolayers. This increase was predominantly via phloretin-sensitive glucose transporter (GLUT)-mediated uptake, which coincided with an increase in GLUT-2 and GLUT-10 abundance. In conclusion, exposure of airway epithelial monolayers to PIMs results in increased paracellular glucose flux, as well as apical GLUT-mediated glucose uptake. However, uptake was insufficient to limit glucose accumulation in ASL. To our knowledge, these data provide for the first time a mechanism to support clinical findings that ASL glucose concentration is increased in patients with airway inflammation.
authors.affiliation: Division of Biomedical Sciences, St. George's, University of London, Tooting, London SW17 0RE, United Kingdom.
authors.forename: James P
authors.initials: JP
authors.lastname: Garnett
authors.forename: Trang T
authors.initials: TT
authors.lastname: Nguyen
authors.forename: James D
authors.initials: JD
authors.lastname: Moffatt
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Pelham
authors.forename: Kameljit K
authors.initials: KK
authors.lastname: Kalsi
authors.forename: Emma H
authors.initials: EH
authors.lastname: Baker
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Baines
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000276:immunology; D002460:Cell Line; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D005947:Glucose / Q000096:biosynthesis / Q000172:deficiency / Q000378:metabolism*; D051246:Glucose Transport Proteins, Facilitative / Q000096:biosynthesis; D051273:Glucose Transporter Type 2 / Q000096:biosynthesis; D006706:Homeostasis / Q000276:immunology*; D006801:Humans; D018836:Inflammation Mediators / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D020545:Respiratory Mucosa / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D013499:Surface Properties; D015854:Up-Regulation / Q000276:immunology
chemical_list: D051246:Glucose Transport Proteins, Facilitative; D051273:Glucose Transporter Type 2; D018836:Inflammation Mediators; C430746:SLC2A10 protein, human; D005947:Glucose