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Development and Identification of a Novel Subpopulation of Human Neutrophil-derived Giant Phagocytes In Vitro
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Published on: January 25, 2017

Macrophage-induced neutrophil apoptosis

A J Meszaros1, J S Reichner, J E Albina

  • 1Department of Surgery, Rhode Island Hospital, Brown University School of Medicine, Providence, RI 02903, USA.

Journal of Immunology (Baltimore, Md. : 1950)
|June 22, 2000
PubMed

Insights

Wound macrophages actively induce polymorphonuclear neutrophil (PMN) apoptosis through direct cell contact. This process requires integrin-ligand interactions and membrane-bound TNF-alpha, crucial for inflammation resolution.

Area of Science:

  • Immunology
  • Cell Biology
  • Wound Healing Research

Background:

  • Macrophages (Mphi) are key in resolving inflammation by clearing apoptotic cells.
  • Polymorphonuclear neutrophils (PMN) are early responders to inflammation.
  • The precise mechanisms by which macrophages induce PMN apoptosis are under investigation.

Purpose of the Study:

  • To investigate the role of wound-associated macrophages in actively inducing PMN apoptosis.
  • To elucidate the molecular mechanisms involved in Mphi-mediated PMN apoptosis.

Main Methods:

  • Coculture of rat wound cells and purified macrophages with PMN-rich populations.
  • Inhibition studies using peptide inhibitors and antibodies against specific molecules (e.g., integrins, TNF-alpha).
  • Transfection of K562 cells to express specific proteins (integrin, membrane-bound TNF-alpha) for mechanistic studies.

Main Results:

  • Wound macrophages significantly increased PMN apoptosis (>3-fold) in coculture experiments.
  • Mphi-induced apoptosis required direct cell-to-cell contact and was not mediated by soluble factors.
  • Inhibition studies implicated integrin-ligand interactions and membrane-bound TNF-alpha in the apoptotic process.
  • Transfected cells demonstrated that combined expression of integrin and membrane-bound TNF-alpha was necessary and sufficient to induce PMN apoptosis.

Conclusions:

  • Wound macrophages possess a constitutive mechanism to induce PMN apoptosis.
  • This mechanism relies on intercellular binding via integrin-ligand interactions and membrane-bound TNF-alpha.
  • These findings highlight a novel pathway for inflammation resolution mediated by macrophages.

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