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Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages
09:09

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Alveolar macrophages are a primary barrier to pulmonary absorption of macromolecules

Catherine Lombry1, David A Edwards, Véronique Préat

  • 1Dept. of Pharmaceutical Technology, School of Pharmacy, Université Catholique de Louvain, Ave. E. Mounier 73 UCL 73.20, 1200 Brussels, Belgium.

American Journal of Physiology. Lung Cellular and Molecular Physiology
|December 26, 2003
PubMed

Insights

Inhaled macromolecules are primarily cleared by lung alveolar macrophages (AM). Minimizing AM uptake enhances protein absorption, suggesting new inhalation delivery methods for therapeutic proteins.

Area of Science:

  • Pulmonary medicine
  • Pharmacology
  • Immunology

Background:

  • Inhaled macromolecules face significant clearance before systemic absorption.
  • Alveolar macrophages (AM) are key players in the elimination of inhaled substances in the lungs.

Purpose of the Study:

  • To investigate the role of alveolar macrophages (AM) in the elimination of inhaled macromolecules.
  • To explore strategies for enhancing systemic absorption of inhaled proteins.

Main Methods:

  • Depletion of AM using liposome-encapsulated dichloromethylene diphosphonate in rats.
  • Intratracheal instillation of macromolecules (IgG, human chorionic gonadotropin).
  • Varying doses of delivered macromolecules to assess absorption and degradation.

Main Results:

  • AM depletion significantly enhanced systemic absorption of IgG and human chorionic gonadotropin.
  • Reduced doses of inhaled IgG decreased local degradation and increased systemic absorption.
  • Demonstrated AM clearance as a primary barrier to inhaled macromolecule absorption.

Conclusions:

  • Alveolar macrophages (AM) are a major barrier to systemic absorption of inhaled macromolecules.
  • Strategies to minimize AM uptake, such as dose reduction or chemical/physical modification, can enhance protein absorption.
  • These findings support the development of inhalation as a viable route for therapeutic protein delivery.

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