Characterization of fibroblast-specific protein 1 in pulmonary fibrosis

Am J Respir Crit Care Med. 2005 Apr 15;171(8):899-907. doi: 10.1164/rccm.200311-1535OC. Epub 2004 Dec 23.


Because fibroblasts produce collagen and other extracellular matrix components that are deposited during tissue fibrosis, defining the behavior of these cells is critical to understanding the pathogenesis of fibrotic diseases. We investigated the utility of fibroblast-specific protein 1 (FSP1), a member of the calmodulin S100 troponin C superfamily, for identifying lung fibroblasts in a murine model of pulmonary fibrosis induced by intratracheal administration of bleomycin. Protein and mRNA expression of FSP1 was minimal in untreated lungs, but increased by 1 week after bleomycin administration and remained increased at 2 and 3 weeks after treatment. By immunohistochemistry, the number of FSP1(+) cells increased in a dose-dependent manner in the lungs after bleomycin treatment. Colocalization of alpha1 procollagen and FSP1 in interstitial cells demonstrated that FSP1(+) fibroblasts contribute to the deposition of collagen after bleomycin administration. In primary lung cell cultures, lung fibroblasts, but not macrophages or type II alveolar epithelial cells, expressed FSP1. FSP1 also identified fibroblasts in lung biopsy specimens from patients with documented usual interstitial pneumonitis. Therefore, FSP1 is an improved marker for lung fibroblasts that could be useful for investigating the pathogenesis of pulmonary fibrosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biopsy
  • Bleomycin / pharmacology
  • Calcium-Binding Proteins / analysis*
  • Calcium-Binding Proteins / genetics
  • Collagen / analysis
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Fibroblasts / drug effects
  • Fibroblasts / pathology
  • Gene Expression
  • Humans
  • Lung / drug effects
  • Lung / pathology
  • Mice
  • Mice, Inbred C57BL
  • Pulmonary Fibrosis / pathology*
  • S100 Calcium-Binding Protein A4
  • S100 Proteins


  • Calcium-Binding Proteins
  • S100 Calcium-Binding Protein A4
  • S100 Proteins
  • S100a4 protein, mouse
  • Bleomycin
  • Collagen