Upregulation of platelet-derived growth factor-A and -B gene expression in alveolar macrophages of individuals with idiopathic pulmonary fibrosis

J Clin Invest. 1990 Jun;85(6):2023-7. doi: 10.1172/JCI114669.


Idiopathic pulmonary fibrosis (IPF) is characterized by accumulation of alveolar macrophages spontaneously releasing exaggerated amounts of the potent mesenchymal cell growth factor platelet-derived growth factor (PDGF). To evaluate the relative contribution of the two PDGF genes to this process, PDGF-A and -B gene transcription rates and mRNA levels were examined in normal and IPF alveolar macrophages. While normal alveolar macrophages constitutively transcribe both PDGF-A and PDGF-B genes, LPS stimulation increases the transcription of both genes more than threefold. Importantly, IPF alveolar macrophages spontaneously transcribe both genes at a rate similar to that observed for normal macrophages after in vitro stimulation. Consistent with the transcription data, normal macrophages contain mRNA for both PDGF-A and -B, but PDGF-B mRNA is 10-fold more abundant. Strikingly, in IPF, both PDGF-A and -B mRNA levels were markedly increased, with persistence of the 10-fold dominance of PDGF-B mRNA. Thus, the exaggerated release of PDGF by IPF alveolar macrophages is likely modulated by upregulated PDGF gene transcription rates and concomitantly increased mRNA levels and the persistent 10-fold excess of B greater than A PDGF mRNA suggests that the PDGF released by alveolar macrophages is likely mostly of the potent B-chain homodimeric form.

MeSH terms

  • Blotting, Northern
  • Gene Expression*
  • Humans
  • Macrophages / physiology*
  • Platelet-Derived Growth Factor / genetics*
  • Pulmonary Alveoli / cytology
  • Pulmonary Fibrosis / genetics*
  • RNA, Messenger / genetics
  • Transcription, Genetic


  • Platelet-Derived Growth Factor
  • RNA, Messenger