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Fibroblast growth factor 2 decreases bleomycin-induced pulmonary fibrosis and inhibits fibroblast collagen production and myofibroblast differentiation.

ABSTRACT: Fibroblast growth factor (FGF) signaling has been implicated in the pathogenesis of pulmonary fibrosis. Mice lacking FGF2 have increased mortality and impaired epithelial recovery after bleomycin exposure, supporting a protective or reparative function following lung injury. To determine whether FGF2 overexpression reduces bleomycin-induced injury, we developed an inducible genetic system to express FGF2 in type II pneumocytes. Double-transgenic (DTG) mice with doxycycline-inducible overexpression of human FGF2 (SPC-rtTA;TRE-hFGF2) or single-transgenic controls were administered intratracheal bleomycin and fed doxycycline chow, starting at either day 0 or day 7. In addition, wild-type mice received intratracheal or intravenous recombinant FGF2, starting at the time of bleomycin treatment. Compared to controls, doxycycline-induced DTG mice had decreased pulmonary fibrosis 21 days after bleomycin, as assessed by gene expression and histology. This beneficial effect was seen when FGF2 overexpression was induced at day 0 or day 7 after bleomycin. FGF2 overexpression did not alter epithelial gene expression, bronchoalveolar lavage cellularity or total protein. In vitro studies using primary mouse and human lung fibroblasts showed that FGF2 strongly inhibited baseline and TGF?1-induced expression of alpha smooth muscle actin (?SMA), collagen, and connective tissue growth factor. While FGF2 did not suppress phosphorylation of Smad2 or Smad-dependent gene expression, FGF2 inhibited TGF?1-induced stress fiber formation and serum response factor-dependent gene expression. FGF2 inhibition of stress fiber formation and ?SMA requires FGF receptor 1 (FGFR1) and downstream MEK/ERK, but not AKT signaling. In summary, overexpression of FGF2 protects against bleomycin-induced pulmonary fibrosis in vivo and reverses TGF?1-induced collagen and ?SMA expression and stress fiber formation in lung fibroblasts in vitro, without affecting either inflammation or epithelial gene expression. Our results suggest that in the lung, FGF2 is antifibrotic in part through decreased collagen expression and fibroblast to myofibroblast differentiation. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

SUBMITTER: Koo HY

PROVIDER: S-EPMC6175645 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Fibroblast growth factor 2 decreases bleomycin-induced pulmonary fibrosis and inhibits fibroblast collagen production and myofibroblast differentiation.

Koo Hyun Young HY El-Baz Lamis Mf LM House StaceyL S Cilvik Sarah N SN Dorry Samuel J SJ Shoukry Nahla M NM Salem Mohamed L ML Hafez Hani S HS Dulin Nickolai O NO Ornitz David M DM Guzy Robert D RD

The Journal of pathology 20180705 1

Fibroblast growth factor (FGF) signaling has been implicated in the pathogenesis of pulmonary fibrosis. Mice lacking FGF2 have increased mortality and impaired epithelial recovery after bleomycin exposure, supporting a protective or reparative function following lung injury. To determine whether FGF2 overexpression reduces bleomycin-induced injury, we developed an inducible genetic system to express FGF2 in type II pneumocytes. Double-transgenic (DTG) mice with doxycycline-inducible overexpressi ...[more]

PMID: 29873400

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Project description:Idiopathic pulmonary fibrosis (IPF) is a progressive disease of insidious onset, and is responsible for up to 30,000 deaths per year in the U.S. Excessive production of extracellular matrix by myofibroblasts has been shown to be an important pathological feature in IPF. TGF-?1 is expressed in fibrotic lung and promotes fibroblast to myofibroblast differentiation (FMD) as well as matrix deposition.To identify the mechanism of Arsenic trioxide's (ATO)'s anti-fibrotic effect in vitro, normal human lung fibroblasts (NHLFs) were treated with ATO for 24 hours and were then exposed to TGF-?1 (1 ng/ml) before harvesting at multiple time points. To investigate whether ATO is able to alleviate lung fibrosis in vivo, C57BL/6 mice were administered bleomycin by oropharyngeal aspiration and ATO was injected intraperitoneally daily for 14 days. Quantitative real-time PCR, western blotting, and immunofluorescent staining were used to assess the expression of fibrotic markers such as ?-smooth muscle actin (?-SMA) and ?-1 type I collagen.Treatment of NHLFs with ATO at very low concentrations (10-20nM) inhibits TGF-?1-induced ?-smooth muscle actin (?-SMA) and ?-1 type I collagen mRNA and protein expression. ATO also diminishes the TGF-?1-mediated contractile response in NHLFs. ATO's down-regulation of profibrotic molecules is associated with inhibition of Akt, as well as Smad2/Smad3 phosphorylation. TGF-?1-induced H2O2 and NOX-4 mRNA expression are also blocked by ATO. ATO-mediated reduction in Smad3 phosphorylation correlated with a reduction of promyelocytic leukemia (PML) nuclear bodies and PML protein expression. PML-/- mouse embryonic fibroblasts (MEFs) showed decreased fibronectin and PAI-1 expression in response to TGF-?1. Daily intraperitoneal injection of ATO (1 mg/kg) in C57BL/6 mice inhibits bleomycin induced lung ?-1 type I collagen mRNA and protein expression.In summary, these data indicate that low concentrations of ATO inhibit TGF-?1-induced fibroblast to myofibroblast differentiation and decreases bleomycin induced pulmonary fibrosis.

Project description:Collagen deposition is a key process during idiopathic pulmonary fibrosis (IPF); however, little is known about the dynamics of collagen formation during disease development. Tissue samples of early stages of human disease are not readily available and it is difficult to identify changes in collagen content, since standard collagen analysis does not distinguish between 'old' and 'new' collagen. Therefore, the current study aimed to (i) investigate the dynamics of new collagen formation in mice using bleomycin-induced lung fibrosis in which newly synthesized collagen was labelled with deuterated water and (ii) use this information to identify genes and processes correlated to new collagen formation from gene expression analysis. Lung fibrosis was induced in female C57BL/6 mice by bleomycin instillation and sacrificed. Animals were sacrificed at 1 to 5 weeks after fibrosis induction. Collagen synthesized during the week before sacrifice was labelled with deuterium by providing mice with deuterated drinking water. After sacrifice, lung tissue was collected for microarray analysis, determination of new collagen formation, and histology. Deuterated water labelling showed a strong increase in new collagen formation already during the first week after fibrosis induction and a complete return to baseline at five weeks. Correlation of new collagen formation data with gene expression data revealed fibrosis specific processes, of which proliferation was an unexpected one. This was confirmed by measuring cell proliferation and collagen synthesis simultaneously using deuterated water incorporation. Furthermore, new collagen formation strongly correlated with gene expression of e.g. elastin, tenascin C, MMP-14, lysyl oxidase, and type V collagen. These data demonstrate, using a novel combination of technologies, that proliferation and extracellular matrix production are correlated to the core process of fibrosis, i.e. the formation of new collagen. In addition, it identified genes directly correlated to fibrosis, thus providing more insight into the aetiology of IPF. Total RNA was obtained from mouse lungs at timepoint 0 as a control (n = 7) or timepoints 1 (n = 7), 2 (n = 6), 3 (n = 6), 4 (n = 6) or 5 (n = 6) weeks after bleomycin-instillation to induce lung fibrosis.

Dataset Information

Fibroblast growth factor 2 decreases bleomycin-induced pulmonary fibrosis and inhibits fibroblast collagen production and myofibroblast differentiation.

Publications

Fibroblast growth factor 2 decreases bleomycin-induced pulmonary fibrosis and inhibits fibroblast collagen production and myofibroblast differentiation.

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