Increased and prolonged pulmonary fibrosis in surfactant protein C-deficient mice following intratracheal bleomycin

Am J Pathol. 2005 Nov;167(5):1267-77. doi: 10.1016/S0002-9440(10)61214-X.

Abstract

Recent reports have linked mutations in the surfactant protein C gene (SFTPC) to familial forms of pulmonary fibrosis, but it is uncertain whether deficiency of mature SP-C contributes to disease pathogenesis. In this study, we evaluated bleomycin-induced lung fibrosis in mice with genetic deletion of SFTPC. Compared with wild-type (SFTPC+/+) controls, mice lacking surfactant protein C (SFTPC-/-) had greater lung neutrophil influx at 1 week after intratracheal bleomycin, greater weight loss during the first 2 weeks, and increased mortality. At 3 and 6 weeks after bleomycin, lungs from SFTPC-/- mice had increased fibroblast numbers, augmented collagen accumulation, and greater parenchymal distortion. Furthermore, resolution of fibrosis was delayed. Although remodeling was near complete in SFTPC+/+ mice by 6 weeks, SFTPC-/- mice did not return to baseline until 9 weeks after bleomycin. By terminal dUTP nick-end labeling staining, widespread cell injury was observed in SFTPC-/- and SFTPC+/+ mice 1 week after bleomycin; however, ongoing apoptosis of epithelial and interstitial cells occurred in lungs of SFTPC-/- mice, but not SFTPC+/+ mice, 6 weeks after bleomycin. Thus, SP-C functions to limit lung inflammation, inhibit collagen accumulation, and restore normal lung structure after bleomycin.

Publication types

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

MeSH terms

  • Animals
  • Apoptosis
  • Bleomycin / toxicity
  • Cells / pathology
  • Collagen / analysis
  • Disease Models, Animal
  • Fibroblasts
  • Hydroxyproline / analysis
  • In Situ Nick-End Labeling
  • Leukocyte Count
  • Lung / pathology
  • Mice
  • Mice, Knockout
  • Neutrophils
  • Peroxidase / analysis
  • Pulmonary Fibrosis / chemically induced
  • Pulmonary Fibrosis / genetics
  • Pulmonary Fibrosis / pathology*
  • Pulmonary Surfactant-Associated Protein C / genetics
  • Pulmonary Surfactant-Associated Protein C / physiology*
  • Weight Loss

Substances

  • Pulmonary Surfactant-Associated Protein C
  • Bleomycin
  • Collagen
  • Peroxidase
  • Hydroxyproline