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

I. Nagaoka, B. C. Trapnell, Ronald Crystal

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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 > A PDGF mRNA suggests that the PDGF released by alveolar macrophages is likely mostly of the potent B-chain homodimeric form.

Original languageEnglish
Pages (from-to)2023-2027
Number of pages5
JournalJournal of Clinical Investigation
Issue number6
Publication statusPublished - 1 Jan 1990
Externally publishedYes



  • fibrosis
  • gene regulation
  • lung
  • macrophage
  • PDGF
  • transcription

ASJC Scopus subject areas

  • Medicine(all)

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