Modulation of prosurvival signaling in fibroblasts by a protein kinase inhibitor protects against fibrotic tissue injury

Am J Pathol. 2005 Feb;166(2):367-75. doi: 10.1016/S0002-9440(10)62260-2.

Abstract

Progressive fibrotic diseases involving diverse organ systems are associated with the persistence of fibroblasts/myofibroblasts in injured tissues. Activation of focal adhesion kinase (FAK) and protein kinase B (PKB/Akt) by transforming growth factor-beta1 mediate stable induction of myofibroblast differentiation and survival. In this report, we demonstrate that transforming growth factor-beta1-induced activation of both PKB/Akt and FAK are dose dependently inhibited by the protein kinase inhibitor, AG1879, in cultured human lung fibroblasts. In a murine model of intratracheal bleomycin-induced lung fibrosis, regions of active fibrogenesis demonstrate elevated expression of PKB/Akt and FAK phosphorylation in vivo, effects that are attenuated in mice receiving daily intraperitoneal injections of AG1879 (bleomycin-AG1879) versus a chemically inactive analog (bleomycin-control). PKB/Akt and FAK phosphorylation are elevated in fibroblasts isolated from lungs of bleomycin-injured mice, effects that are inhibited in bleomycin-AG1879 mice. Accumulation of alpha-smooth muscle actin-expressing myofibroblasts is markedly reduced in lungs of bleomycin-AG1879 mice. The numbers of recruited inflammatory cells were not significantly different between these groups. Bleomycin-AG1879 mice are protected from lung fibrosis as evidenced by histopathology, trichrome staining, and biochemical analysis for collagen. Thus, targeting of prosurvival signaling pathways in fibroblasts/myofibroblasts may provide a novel and effective strategy for anti-fibrotic therapy of treatment-unresponsive fibrotic disorders.

Publication types

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

MeSH terms

  • Actins / metabolism
  • Animals
  • Bleomycin / pharmacology
  • Cell Survival
  • Collagenases / metabolism
  • Enzyme Inhibitors / pharmacology
  • Fibroblasts / metabolism*
  • Fibrosis
  • Focal Adhesion Kinase 1
  • Focal Adhesion Protein-Tyrosine Kinases
  • Immunohistochemistry
  • Inflammation
  • Lung / metabolism
  • Lung / pathology
  • Mice
  • Mice, Inbred C57BL
  • Muscle, Smooth / metabolism
  • Phenotype
  • Phosphorylation
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Serine-Threonine Kinases / metabolism
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Pyrimidines / pharmacology
  • Signal Transduction
  • Transforming Growth Factor beta / metabolism
  • Transforming Growth Factor beta1
  • src-Family Kinases / antagonists & inhibitors

Substances

  • AG 1879
  • Actins
  • Enzyme Inhibitors
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins
  • Pyrimidines
  • TGFB1 protein, human
  • Tgfb1 protein, mouse
  • Transforming Growth Factor beta
  • Transforming Growth Factor beta1
  • Bleomycin
  • Protein-Tyrosine Kinases
  • Focal Adhesion Kinase 1
  • Focal Adhesion Protein-Tyrosine Kinases
  • Ptk2 protein, mouse
  • src-Family Kinases
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Collagenases