title: Absence of Thy-1 results in TGF-β induced MMP-9 expression and confers a profibrotic phenotype to human lung fibroblasts.
abstract: Fibroblasts differ in a variety of phenotypic features, including the expression of Thy-1 a glycophosphatidylinositol-linked glycoprotein. Fibroblasts in idiopathic pulmonary fibrosis (IPF) are Thy-1 negative, whereas most fibroblasts from normal lungs are Thy-1 positive. However, the functional consequences of the absence of Thy-1 are not fully understood. We analyzed the expression of Thy-1 in several primary fibroblasts lines derived from IPF, hypersensitivity pneumonitis (HP), and normal human lungs. We found that a high proportion, independently of their origin, expressed Thy-1 in vitro. We identified a primary culture of HP fibroblasts, which did not express Thy-1, and compared several functional activities between Thy-1 (-) and Thy-1 (+) fibroblasts. Thy-1 (-) fibroblasts were smaller (length: 41.3±20.8 μ versus 83.1±40 μ), showed increased proliferative capacity and enhanced PDGF-induced transmigration through collagen I (59.9% versus 42.2% over control under basal conditions, P<0.01). Likewise, Thy-1 (-) fibroblasts either spontaneously or after TGF-β stimulation demonstrated stronger contraction of collagen matrices (eg, 0.17±0.03 versus 0.6±0.05 cm² after TGF-β stimulation at 24 h; P<0.01). Thy-1 (-) lung fibroblasts stimulated with TGF-β1 expressed MMP-9, an enzyme that is usually not produced by lung fibroblasts. TGFβ-induced MMP-9 expression was reversible upon re-expression of Thy-1 after transfection with full-length Thy-1. β-glycan, a TGF-β receptor antagonist abolished MMP-9 expression. TGF-β1-induced MMP-9 in Thy-1 (-) fibroblasts depended on the activation of ERK1/2 signaling pathway. Finally, we demonstrated that fibroblasts from IPF fibroblastic foci, which do not express Thy-1 exhibit strong staining for immunoreactive MMP-9 protein in vivo. These findings indicate that loss of Thy-1 in human lung fibroblasts induces a fibrogenic phenotype.
authors.affiliation: Facultad de Ciencias, Universidad Nacional Autónoma de México, México DF, México.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Ramírez
authors.forename: James S
authors.initials: JS
authors.lastname: Hagood
authors.forename: Yan
authors.initials: Y
authors.lastname: Sanders
authors.forename: Remedios
authors.initials: R
authors.lastname: Ramírez
authors.forename: Carina
authors.initials: C
authors.lastname: Becerril
authors.forename: Lourdes
authors.initials: L
authors.lastname: Segura
authors.forename: Lourdes
authors.initials: L
authors.lastname: Barrera
authors.forename: Moisés
authors.initials: M
authors.lastname: Selman
authors.forename: Annie
authors.initials: A
authors.lastname: Pardo
mesh_terms: D000542:Alveolitis, Extrinsic Allergic / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D002465:Cell Movement; D049109:Cell Proliferation; D003094:Collagen / Q000502:physiology; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D005355:Fibrosis; D018014:Gene Transfer Techniques; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000378:metabolism* / Q000473:pathology; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D020935:MAP Kinase Signaling System; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008875:Middle Aged; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D018800:Thy-1 Antigens / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014945:Wound Healing
chemical_list: D012333:RNA, Messenger; D018800:Thy-1 Antigens; D016212:Transforming Growth Factor beta; D003094:Collagen; D048049:Extracellular Signal-Regulated MAP Kinases; D020780:Matrix Metalloproteinase 9