الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 10 |  |  |
| | | from | 10 | | |
Abstract
In the current study, a doxycycline-inducible transgenic allele was used to model FGF2 therapy in mice. The main goal of this study was to determine whether FGF2 overexpression reduces bleomycin-induced injury in vivo and to address FGF2 effect on human lung epithelial cells in vitro after injury using TGFβ1. Overexpression of FGF2 in the uninjured lung does not, by itself, cause pulmonary fibrosis or increased collagen production. However, FGF2 overexpression decreased bleomycin-induced pulmonary fibrosis, collagen accumulation, and collagen expression. This effect was seen when FGF2 was induced at the time of bleomycin and beginning 7 days after bleomycin. FGF2 overexpression did not alter inflammation, acute lung injury (measured by BAL protein), or epithelial-specific gene expression (such as Sftpc, Cdh1 and Scgb1a1). Therefore, in the current study, the effect of recombinant FGF2 on lung bronchial (BEAS-2B) and alveolar (A549) epithelial cells after injury using TGFβ1 in vitro was demonstrated. TGFβ1 induces EMT in human bronchial epithelial cells (BEAS-2B) as shown by morphological changes from cobblestone to elongated spindle like shape. FGF2 enhances TGFβ1-induced EMT related gene expression by downregulating of the epithelial cell-specific adherence junction protein CDH1 and upregulation of the mesenchymal markers ACTA2 and CDH2. Moreover, FGF2 augments the increase in the ECM mRNA expression of FN and TNC induced by TGFβ1 in BEAS-2B cells. Additionally, epithelial migration was enhanced by pre-treatment with FGF2 and/or TGFβ1. A similar pattern of EMT gene expression was observed following stimulation in alveolar type II epithelial cells (A549) cells, suggesting that FGF2 augments TGFβ1 in inducing EMT in multiple lung epithelial cell lines in vitro. 2 TGFβ1 treatment significantly increases COL1A1 expression in both BEAS-2B and A549 cells. However, interestingly, COL1A1 expression was dramatically suppressed with the addition of FGF2 to TGFβ1-treated BEAS-2B and A549 cells. The addition of PD173074 found to attenuate the inductive effect of FGF2 suggesting that the effect of FGF2 is dependent upon canonical signaling through FGFRs. These results support the in vivo findings that FGF2 has an antifibrotic effect through suppression collagen expression induced by TGFβ1 in lung epithelial cells and by bleomycin in mouse lung. To the best of our knowledge, this is the first report of an antifibrotic effect of FGF2 in the lung in vivo. Furthermore, to our knowledge, the synergistic effect between FGF2 and TGFβ1 in inducing type II EMT in lung epithelial cells in vitro had not been addressed previously. As outcomes in pulmonary fibrosis and IPF remain poor despite the emergence of antifibrotic agents, this research will serve as a base for future studies in understanding the factors and underlying mechanisms of FGF2-dependent pathways in different types of cells.