[HTML][HTML] Absence of Thy-1 results in TGF-β induced MMP-9 expression and confers a profibrotic phenotype to human lung fibroblasts

G Ramírez, JS Hagood, Y Sanders, R Ramírez… - Laboratory …, 2011 - nature.com
G Ramírez, JS Hagood, Y Sanders, R Ramírez, C Becerril, L Segura, L Barrera, M Selman
Laboratory investigation, 2011nature.com
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 …
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 cm 2 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.
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