title: Immunosuppression-induced bronchial epithelial-mesenchymal transition: a potential contributor to obliterative bronchiolitis.
abstract: OBJECTIVE
  Obliterative bronchiolitis is the predominant histopathologic finding in patients with chronic rejection after lung transplant. This fibroproliferative transformation within small airways of lung allograft is poorly understood; however, studies suggest epithelial-mesenchymal transition plays a role. Transplant immunosuppressive therapy has been shown to cause epithelial-mesenchymal transition in renal tubular epithelial cells, with subsequent fibrosis. This study explored whether immunosuppressive therapy contributes to epithelial-mesenchymal transition in airway epithelial cells.
  
  
  METHODS
  Bronchial epithelial cell line RL-65 was treated 3 to 5 days with several immunosuppressive agents, including cyclosporine (INN ciclosporin), tacrolimus, azathioprine, mycophenolic acid, sirolimus, prednisone, and transforming growth factor β1 as control. We then analyzed cells for presence of mesenchymal morphology and protein markers.
  
  
  RESULTS
  Treatment with cyclosporine, azathioprine, mycophenolate, and sirolimus resulted in elongated and irregular cell shape, and all but azathioprine showed loss of cell-cell adhesions relative to vehicle-treated cells. Expressions of extracellular matrix proteins, fibronectin and collagen, along with mesenchymal marker, vimentin, were significantly upregulated. Immunofluorescence showed loss of E-cadherin at cell membranes and cytoskeletal rearrangements typical of epithelial-mesenchymal transition. These immunosuppressive agents also increased transforming growth factor produced by cells; however, tacrolimus- and prednisone-treated cells maintained epithelial morphology, baseline levels of matrix protein expression, and transforming growth factor production levels.
  
  
  CONCLUSIONS
  Overall, we found that certain immunosuppressive agents may contribute to partial epithelial-mesenchymal transition in bronchial epithelial cells, specifically increasing production of excessive extracellular matrix proteins. This may provide novel insights into the pathogenesis of obliterative bronchiolitis after lung transplant.
authors.affiliation: Center for Thoracic Disease, Heart and Lung Institute, St Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
authors.forename: Valerie M
authors.initials: VM
authors.lastname: Felton
authors.forename: Landon J
authors.initials: LJ
authors.lastname: Inge
authors.forename: Brigham C
authors.initials: BC
authors.lastname: Willis
authors.forename: Ross M
authors.initials: RM
authors.lastname: Bremner
authors.forename: Michael A
authors.initials: MA
authors.lastname: Smith
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001980:Bronchi / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D001989:Bronchiolitis Obliterans / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D048430:Cell Shape / Q000187:drug effects; D003094:Collagen / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D005353:Fibronectins / Q000378:metabolism; D005355:Fibrosis; D007166:Immunosuppressive Agents / Q000633:toxicity*; D051381:Rats; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
chemical_list: D015415:Biomarkers; D015820:Cadherins; D005353:Fibronectins; D007166:Immunosuppressive Agents; C508962:Tgfb1 protein, rat; D053773:Transforming Growth Factor beta1; D014746:Vimentin; D003094:Collagen