Differential expression of extracellular matrix remodeling genes in a murine model of bleomycin-induced pulmonary fibrosis

Am J Pathol. 1998 Mar;152(3):821-8.


Exposure to the chemotherapeutic drug bleomycin leads to pulmonary fibrosis in humans and has been widely used in animal models of the disease. Using C57BL/6 bleomycin-sensitive mice, pulmonary fibrosis was induced by multiple intraperitoneal injections of the drug. An increase in the relative amounts of steady-state alpha1(I) procollagen, alpha1(III) procollagen, and fibronectin mRNA as well as histopathological evidence of fibrosis was observed. The effect of bleomycin on the expression of the enzymes responsible for extracellular matrix degradation, the matrix metalloproteinases (MMPs), and their inhibitors (TIMPs), was selective and showed temporal differences during the development of fibrosis. Of the MMPs tested, bleomycin treatment resulted in the up-regulation of gelatinase A and macrophage metalloelastase gene expression in whole-lung homogenates, whereas gelatinase B, stromelysin-1, and interstitial collagenase gene expression was not significantly changed. Timp2 and Timp3, the murine homologues of the respective TIMP genes, were constitutively expressed, whereas Timp1 was markedly up-regulated during fibrosis. The strong correlation between enhanced extracellular matrix gene expression, differential MMP and TIMP gene expression, and histopathological evidence of fibrosis suggest that dysregulated matrix remodeling is likely to contribute to the pathology of bleomycin-induced pulmonary fibrosis.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Bleomycin
  • Disease Models, Animal
  • Extracellular Matrix / enzymology*
  • Female
  • Fibronectins / genetics
  • Fibronectins / metabolism
  • Gelatinases / genetics
  • Gelatinases / metabolism*
  • Gene Expression Regulation, Enzymologic*
  • Immunohistochemistry
  • Lung / enzymology
  • Metalloendopeptidases / genetics
  • Metalloendopeptidases / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Procollagen / genetics
  • Procollagen / metabolism
  • Pulmonary Fibrosis / chemically induced
  • Pulmonary Fibrosis / enzymology*
  • Pulmonary Fibrosis / pathology
  • RNA, Messenger / metabolism
  • Specific Pathogen-Free Organisms
  • Tissue Inhibitor of Metalloproteinases / genetics
  • Tissue Inhibitor of Metalloproteinases / metabolism*
  • Up-Regulation


  • Fibronectins
  • Procollagen
  • RNA, Messenger
  • Tissue Inhibitor of Metalloproteinases
  • Bleomycin
  • Gelatinases
  • Metalloendopeptidases