title: Induction of epithelial-mesenchymal transition in primary airway epithelial cells from patients with asthma by transforming growth factor-beta1.
abstract: BACKGROUND
  Airway remodeling in asthma is associated with the accumulation of fibroblasts, the primary cell responsible for synthesis and secretion of extracellular matrix proteins. The process by which the number of fibroblasts increases in asthma is poorly understood, but epithelial-mesenchymal transition (EMT) may play a significant role.
  
  
  OBJECTIVE
  To evaluate whether EMT occurs in primary airway epithelial cells (AECs), the mechanisms involved, and if this process is altered in asthmatic AECs.
  
  
  METHODS
  AECs were obtained from subjects with asthma (n = 8) and normal subjects without asthma (n = 10). Monolayer and air-liquid interface-AEC (ALI-AEC) cultures were treated with transforming growth factor (TGF)-beta1 (10 ng/ml) for 72 hours and assayed for mesenchymal and epithelial markers using quantitative polymerase chain reaction, confocal microscopy, and immunoblot. The involvement of BMP-7, Smad3, and MAPK-mediated signaling were also evaluated.
  
  
  RESULTS
  TGF-beta1-induced EMT in AEC monolayers derived from subjects with asthma and normal donors. EMT was characterized by changes in cell morphology, increased expression of mesenchymal markers EDA-fibronectin, vimentin, alpha-smooth muscle actin, and collagen-1, and loss of epithelial markers E-cadherin and zonular occludin-1. Inhibition of TGF-beta1-induced signaling with Smad3-inhibiting siRNA or TGF-beta1-neutralizing antibodies prevented and reversed EMT, respectively, whereas BMP-7 had no effect. In ALI-AEC cultures derived from normal subjects, EMT was confined to basally situated cells, whereas in asthmatic ALI-AEC cultures EMT was widespread throughout the epithelium.
  
  
  CONCLUSIONS
  TGF-beta1 induces EMT in a Smad3-dependent manner in primary AECs. However, in asthmatic-derived ALI-AEC cultures, the number of cells undergoing EMT is greater. These findings support the hypothesis that epithelial repair in asthmatic airways is dysregulated.
authors.affiliation: James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Disease, St. Paul's Hospital, 1081 Burrard Street, Vancouver, BC, Canada. thackett@mrl.ubc.ca
authors.forename: Tillie-Louise
authors.initials: TL
authors.lastname: Hackett
authors.forename: Stephanie Mary
authors.initials: SM
authors.lastname: Warner
authors.forename: Dorota
authors.initials: D
authors.lastname: Stefanowicz
authors.forename: Furquan
authors.initials: F
authors.lastname: Shaheen
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Pechkovsky
authors.forename: Lynne A
authors.initials: LA
authors.lastname: Murray
authors.forename: Rochelle
authors.initials: R
authors.lastname: Argentieri
authors.forename: Anthony
authors.initials: A
authors.lastname: Kicic
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Stick
authors.forename: Tony R
authors.initials: TR
authors.lastname: Bai
authors.forename: Darryl A
authors.initials: DA
authors.lastname: Knight
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D016022:Case-Control Studies; D018929:Cell Culture Techniques; D054337:Cell Dedifferentiation / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D004847:Epithelial Cells / Q000187:drug effects* / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000502:physiology; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000502:physiology; D008297:Male; D059630:Mesenchymal Stem Cells; D011994:Recombinant Proteins; D015398:Signal Transduction; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D016326:Extracellular Matrix Proteins; D036341:Intercellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D053773:Transforming Growth Factor beta1