Extracellular matrix deposition by primary human lung fibroblasts in response to TGF-beta1 and TGF-beta3

Am J Physiol. 1999 May;276(5):L814-24. doi: 10.1152/ajplung.1999.276.5.L814.


Increased collagen and extracellular matrix (ECM) deposition within the lung is a characteristic feature of lung fibrosis. Transforming growth factor (TGF)-beta isoforms play a pivotal role in the production of collagen and ECM. In this study, we investigated the effects of TGF-beta1 and TGF-beta3 on the main processes controlling ECM deposition using primary human lung fibroblasts. We analyzed 1) collagen metabolism by [3H]proline incorporation, 2) matrix metalloproteinase (MMP) expression by substrate gel zymography, and 3) tissue inhibitor of metalloproteinases (TIMP) expression by Western blot analysis. TGF-beta1 and TGF-beta3 increased the percentage of secreted collagens in supernatants of primary fibroblasts from 8.0 +/- 1.2 (control) to 23.6 +/- 4.6 and 22.3 +/- 1.3%, respectively. The collagen percentage in deposited ECM was increased from 5.8 +/- 0.3 (control) to 9.0 +/- 0.5 and 8.8 +/- 0.5% by TGF-beta1 and TGF-beta3, respectively. Secretion of MMP-1 (interstitial collagenase) by fibroblasts was reduced by both TGF-beta isoforms, whereas secretion of MMP-2 (gelatinase A) was unaffected by either of the two isoforms. Both TGF-beta isoforms increased TIMP-1 protein expression, whereas TIMP-2 protein was decreased. We thus conclude that TGF-beta1 and TGF-beta3 are equally potent in increasing ECM deposition. Their fibrotic effect in lung fibroblasts results from 1) an increase in the secretion and deposition of total ECM and collagens, 2) a decrease in MMP-1 secretion, and 3) an increase of TIMP-1 expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Cells, Cultured
  • Collagen / metabolism
  • Collagenases / metabolism
  • Extracellular Matrix / metabolism*
  • Fibroblasts / metabolism*
  • Fibroblasts / ultrastructure*
  • Gelatinases / metabolism
  • Humans
  • Matrix Metalloproteinase 1
  • Matrix Metalloproteinase 2
  • Metalloendopeptidases / metabolism
  • Proline / metabolism
  • Tissue Inhibitor of Metalloproteinase-1 / analysis
  • Tissue Inhibitor of Metalloproteinase-2 / analysis
  • Transforming Growth Factor beta / pharmacology*
  • Tritium


  • Tissue Inhibitor of Metalloproteinase-1
  • Transforming Growth Factor beta
  • Tritium
  • Tissue Inhibitor of Metalloproteinase-2
  • Collagen
  • Proline
  • Collagenases
  • Gelatinases
  • Metalloendopeptidases
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 1