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Potential role of apoptotic macrophages in pulmonary inflammation and fibrosis

Liying Wang1, James M Antonini, Yon Rojanasakul

  • 1National Institute for Occupational Safety and Health, Physiology and Pathology Research Branch, Morgantown, West Virginia 26505, USA. lmw6@cdc.gov

Journal of Cellular Physiology
|December 21, 2002
PubMed

Insights

Apoptotic macrophages directly induce lung inflammation and fibrosis in rats. This process involves increased macrophage infiltration and expression of key proteins like TNF-alpha and TGF-beta.

Area of Science:

  • Pulmonary immunology
  • Cellular biology
  • Pathology

Background:

  • Apoptosis induction is linked to inflammatory and fibrotic lung diseases.
  • The specific role of apoptotic macrophages in lung disorders remains unclear.

Purpose of the Study:

  • To investigate the direct effects of apoptotic macrophages on lung inflammation and fibrosis.
  • To examine the protein expression of TNF-alpha, TGF-beta, and MMPs following apoptotic macrophage instillation.

Main Methods:

  • Macrophage apoptosis was induced in vitro.
  • Apoptotic macrophages were instilled intratracheally into rats.
  • Lung inflammation, fibrosis, and protein expression were assessed using histology, TUNEL assay, and immunohistochemistry.

Main Results:

  • Instillation of apoptotic macrophages, but not control macrophages or saline, led to increased macrophage infiltration and lung cell apoptosis.
  • Histological analysis revealed collagen deposition and fibrotic lesions in lungs treated with apoptotic macrophages.
  • Increased expression of TNF-alpha, TGF-beta, MMP2, and MMP9 was observed in the treatment group.

Conclusions:

  • Macrophage apoptosis plays a role in initiating lung inflammation and fibrosis.
  • Apoptotic macrophages can directly induce pulmonary fibrosis and inflammation.
  • This induction is associated with elevated levels of TNF-alpha, TGF-beta, MMP2, and MMP9.

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