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Updated: Feb 13, 2026

Harvesting Murine Alveolar Macrophages and Evaluating Cellular Activation Induced by Polyanhydride Nanoparticles
Published on: June 8, 2012
New interplay between interstitial and alveolar macrophages explains pulmonary alveolar proteinosis (PAP) induced by
François Huaux1, Valentin De Gussem2, Astrid Lebrun2
1Louvain Centre for Toxicology and Applied Pharmacology (LTAP), Institut de Recherche Experimentale et Clinique (IREC), Université catholique de Louvain, Avenue Mounier 53 bte B1.52.12, 1200, Brussels, Belgium. francois.huaux@uclouvain.be.
Abstract:
Occupational exposure to indium tin oxide (ITO) particles has been associated with the development of severe lung diseases, including pulmonary alveolar proteinosis (PAP). The mechanisms of this lung toxicity remain unknown. Here, we reveal the respective roles of resident alveolar (Siglec-Fhigh AM) and recruited interstitial (Siglec-Flow IM) macrophages contributing in concert to the development of PAP. In mice treated with ITO particles, PAP is specifically associated with IL-1α (not GM-CSF) deficiency and Siglec-Fhigh AM (not Siglec-Flow IM) depletion. Mechanistically, ITO particles are preferentially phagocytosed and dissolved to soluble In3+ by Siglec-Flow IM. In contrast, Siglec-Fhigh AM weakly phagocytose or dissolve ITO particles, but are sensitive to released In3+ through the expression of the transferrin receptor-1 (TfR1). Blocking pulmonary Siglec-Flow IM recruitment in CCR2-deficient mice reduces ITO particle dissolution, In3+ release, Siglec-Fhigh AM depletion, and PAP formation. Restoration of IL-1-related Siglec-Fhigh AM also prevented ITO-induced PAP. We identified a new mechanism of secondary PAP development according to which metal ions released from inhaled particles by phagocytic IM disturb IL-1α-dependent AM self-maintenance and, in turn, alveolar clearance.
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