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Am J Respir Crit Care Med. 2008 Mar 15;177(6):638-45. Epub 2007 Dec 20.

An essential role for fibronectin extra type III domain A in pulmonary fibrosis.

Author information

1
Division of Pulmonary and Critical Care Medicine, University of Michigan Medical School, 6301 MSRB III/0642, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0642, USA.

Abstract

RATIONALE:

Tissue fibrosis is considered a dysregulated wound-healing response. Fibronectin containing extra type III domain A (EDA) is implicated in the regulation of wound healing. EDA-containing fibronectin is deposited during wound repair, and its presence precedes that of collagen.

OBJECTIVES:

To investigate the role of EDA-containing fibronectin in lung fibrogenesis.

METHODS:

Primary lung fibroblasts from patients with idiopathic pulmonary fibrosis or from patients undergoing resection for lung cancer were assessed for EDA-containing fibronectin and alpha-smooth muscle actin (alpha-SMA) expression. Mice lacking the EDA domain of fibronectin and their wild-type littermates were challenged with the bleomycin model of lung fibrosis. Primary lung fibroblasts from these mice were assayed in vitro to determine the contribution of EDA-containing fibronectin to fibroblast phenotypes.

MEASUREMENTS AND MAIN RESULTS:

Idiopathic pulmonary fibrosis lung fibroblasts produced markedly more EDA-containing fibronectin and alpha-SMA than control fibroblasts. EDA-null mice failed to develop significant fibrosis 21 days after bleomycin challenge, whereas wild-type controls developed the expected increase in total lung collagen. Histologic analysis of EDA-null lungs after bleomycin showed less collagen and fewer alpha-SMA-expressing myofibroblasts compared with that observed in wild-type mice. Failure to develop lung fibrosis in EDA-null mice correlated with diminished activation of latent transforming growth factor (TGF)-beta and decreased lung fibroblast responsiveness to active TGF-beta in vitro.

CONCLUSIONS:

The data show that EDA-containing fibronectin is essential for the fibrotic resolution of lung injury through TGF-beta activation and responsiveness, and suggest that EDA-containing fibronectin plays a critical role in tissue fibrogenesis.

PMID:
18096707
PMCID:
PMC2267338
DOI:
10.1164/rccm.200708-1291OC
[Indexed for MEDLINE]
Free PMC Article

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