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Updated: Dec 26, 2025
Harvesting Murine Alveolar Macrophages and Evaluating Cellular Activation Induced by Polyanhydride Nanoparticles
Published on: June 8, 2012
Appearance of Alveolar Macrophage Subpopulations in Correlation With Histopathological Effects in Short-Term
Johanna Koltermann-Jülly1,2, Lan Ma-Hock1, Sibylle Gröters1
1Experimental Toxicology and Ecology, BASF, Ludwigshafen, Germany.
Abstract:
Following inhalation and deposition in the alveolar region at sufficient dose, biopersistent (nano)materials generally provoke pulmonary inflammation. Alveolar macrophages (AMs) are mediators of pulmonary immune responses and were broadly categorized in pro-inflammatory M1 and anti-inflammatory M2 macrophages. This study aimed at identifying AM phenotype as M1 or M2 upon short-term inhalation exposure to different (nano)materials followed by a postexposure period. Phenotyping of AM was retrospectively performed using immunohistochemistry. M1 (CD68+iNOS+) and M2 (CD68+CD206+ and CD68+ArgI+) AMs were characterized in formalin-fixed, paraffin-embedded lung tissue of rats exposed for 6 hours/day for 5 days to air, 100 mg/m3 nano-TiO2, 25 mg/m3 nano-CeO2, 32 mg/m3 multiwalled carbon nanotubes, or 100 mg/m3 micron-sized quartz. During acute inflammation, relative numbers of M1 AMs were markedly increased, whereas relative numbers of M2 were generally decreased compared to control. Following an exposure-free period, changes in iNOS or CD206 expression correlated with persistence, regression, or progression of inflammation, suggesting a role of M1/M2 AMs in the pathogenesis of pulmonary inflammation. However, no clear correlation of AM subpopulations with qualitatively distinct histopathological findings caused by different (nano)materials was found. A more detailed understanding of the processes underlaying these morphological changes is needed to identify biomarkers for different histopathological outcomes.
Insights
Inhaled nanomaterials trigger pulmonary inflammation by altering alveolar macrophage (AM) phenotypes, shifting towards pro-inflammatory M1 types. AM responses correlate with inflammation progression, but distinct material effects on histopathology remain unclear.
Area of Science:
- Pulmonary toxicology
- Immunology
- Nanomaterial science
Background:
- Biopersistent (nano)materials inhaled into the lungs typically induce inflammation.
- Alveolar macrophages (AMs) are key immune cells, classified as pro-inflammatory (M1) or anti-inflammatory (M2).
Purpose of the Study:
- To determine AM phenotypes (M1 or M2) after short-term inhalation of various (nano)materials and a subsequent exposure-free period.
- Investigate the role of AM subpopulations in pulmonary inflammation pathogenesis.
Main Methods:
- Rats were exposed to air, nano-TiO2, nano-CeO2, carbon nanotubes, or quartz.
- AM phenotypes were assessed using immunohistochemistry (CD68, iNOS, CD206, ArgI) in lung tissue.
- Analysis included acute inflammation and post-exposure periods.
Main Results:
- Exposure to (nano)materials increased M1 AMs and decreased M2 AMs during acute inflammation.
- Post-exposure, changes in iNOS and CD206 expression correlated with inflammation dynamics (persistence, regression, progression).
- No clear link was found between AM subpopulations and distinct material-induced histopathological changes.
Conclusions:
- AM polarization (M1/M2 balance) is involved in pulmonary inflammation following (nano)material inhalation.
- Further research is needed to understand morphological changes and identify biomarkers for specific histopathological outcomes.
