title: Involvement of epithelial-mesenchymal transition in methotrexate-induced pulmonary fibrosis.
abstract: Epithelial-mesenchymal transition (EMT) plays a pivotal event in the development of pulmonary fibrosis. We have previously reported that methotrexate (MTX)-induced alveolar epithelial cell injury followed by pulmonary fibrosis as a result of the recruitment and proliferation of myofibroblasts. However, there is no data concerning whether EMT occurs in MTX-induced pulmonary fibrosis. In the present study, therefore, we investigated the expression of EMT markers such as E-cadherin, α-SMA, and vimentin by immunofluorescence analysis in mouse lung tissues after administration of MTX. We found that vimentin and α-SMA-positive cells of the MTX-induced pulmonary fibrosis were increased; on the other hand, E-cadherin was decreased, indicating that epithelial cells act as the main source of mesenchymal expansion. These results exhibited the down-regulation of E-cadherin expression and the up-regulation of α-smooth muscle actin (α-SMA) in primary mouse alveolar epithelial cells (MAECs) and A549 cell lines. Additionally, MTX-induced A549 cells exhibited an EMT-like phenotype accompanied by the elevation of the expression of interleukin-6 (IL-6) and transforming growth factor (TGF)-β1, as well as an enhancement of migration. All of these findings suggest that MTX-induced pulmonary fibrosis occurs via EMT.
authors.affiliation: Division of Clinical Pharmacy, Department of Pharmacotherapeutics, School of Pharmacy, Showa University.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ohbayashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kubota
authors.forename: Aya
authors.initials: A
authors.lastname: Kawase
authors.forename: Noriko
authors.initials: N
authors.lastname: Kohyama
authors.forename: Yasuna
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Toshinori
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008727:Methotrexate / Q000009:adverse effects*; D051379:Mice; D058628:Myofibroblasts / Q000166:cytology / Q000187:drug effects / Q000473:pathology; D011650:Pulmonary Alveoli / Q000166:cytology; D011658:Pulmonary Fibrosis / Q000235:genetics / Q000503:physiopathology*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D014746:Vimentin / Q000378:metabolism
chemical_list: D000199:Actins; D015820:Cadherins; D015850:Interleukin-6; D053773:Transforming Growth Factor beta1; D014746:Vimentin; C544013:alpha-smooth muscle actin, mouse; D008727:Methotrexate