The role of macrophages in the clearance of inhaled ultrafine titanium dioxide particles

Geiser, Marianne; Casaulta, Marco; Kupferschmid, Barbara; Schulz, Holger; Semmler-Behnke, Manuela; Kreyling, Wolfgang (2008). The role of macrophages in the clearance of inhaled ultrafine titanium dioxide particles. American journal of respiratory cell and molecular biology, 38(3), pp. 371-6. New York, N.Y.: American Lung Association 10.1165/rcmb.2007-0138OC

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The role of macrophages in the clearance of particles with diameters less than 100 nm (ultrafine or nanoparticles) is not well established, although these particles deposit highly efficiently in peripheral lungs, where particle phagocytosis by macrophages is the primary clearance mechanism. To investigate the uptake of nanoparticles by lung phagocytes, we analyzed the distribution of titanium dioxide particles of 20 nm count median diameter in macrophages obtained by bronchoalveolar lavage at 1 hour and 24 hours after a 1-hour aerosol inhalation. Differential cell counts revealing greater than 96% macrophages and less than 1% neutrophils and lymphocytes excluded inflammatory cell responses. Employing energy-filtering transmission electron microscopy (EFTEM) for elemental microanalysis, we examined 1,594 macrophage profiles in the 1-hour group (n = 6) and 1,609 in the 24-hour group (n = 6). We found 4 particles in 3 macrophage profiles at 1 hour and 47 particles in 27 macrophage profiles at 24 hours. Model-based data analysis revealed an uptake of 0.06 to 0.12% ultrafine titanium-dioxide particles by lung-surface macrophages within 24 hours. Mean (SD) particle diameters were 31 (8) nm at 1 hour and 34 (10) nm at 24 hours. Particles were localized adjacent (within 13-83 nm) to the membrane in vesicles with mean (SD) diameters of 592 (375) nm at 1 hour and 414 (309) nm at 24 hours, containing other material like surfactant. Additional screening of macrophage profiles by conventional TEM revealed no evidence for agglomerated nanoparticles. These results give evidence for a sporadic and rather unspecific uptake of TiO(2)-nanoparticles by lung-surface macrophages within 24 hours after their deposition, and hence for an insufficient role of the key clearance mechanism in peripheral lungs.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy > Cell Biology 04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy
UniBE Contributor:	Geiser, Marianne
ISSN:	1044-1549
ISBN:	17947511
Publisher:	American Lung Association
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:55
Last Modified:	05 Dec 2022 14:17
Publisher DOI:	10.1165/rcmb.2007-0138OC
PubMed ID:	17947511
Web of Science ID:	000253435500017
URI:	https://boris.unibe.ch/id/eprint/23529 (FactScience: 42212)