Abstract
We used stable water suspensions of copper oxide particles with mean diameter 20 nm and of particles containing copper oxide and element copper with mean diameter 340 nm to assess the pulmonary phagocytosis response of rats to a single intratracheal instillation of these suspensions using optical, transmission electron, and semi-contact atomic force microscopy and biochemical indices measured in the bronchoalveolar lavage fluid. Although both nano and submicron ultrafine particles were adversely bioactive, the former were found to be more toxic for lungs as compared with the latter while evoking more pronounced defense recruitment of alveolar macrophages and especially of neutrophil leukocytes and more active phagocytosis. Based on our results and literature data, we consider both copper solubilization and direct contact with cellular organelles (mainly, mitochondria) of persistent particles internalized by phagocytes as probable mechanisms of their cytotoxicity.
Highlights
Nanoparticles (NPs) of metals and of their oxides are of special interest for industrial toxicologists because, along with engineered metal-containing NPs, there exists usually a substantial fraction of nanoscale (“ultrafine”) particles of the same or chemically close substances within the particle size distribution of condensation aerosols generated by arc-welding and metallurgical technologies
It can be seen that (1) both NPs and micrometer particles (MPs) cause a substantial increase over the control value in the number of neutrophil leukocytes (NL) as well as a significant but less pronounced increase in the number of alveolar macrophages (AM) in the BALF and, a sharp increase in the NL/AM ratio; (2) this ratio is considerably and statistically significantly higher for NPs as compared with MPs due to both a much higher NL count and a somewhat lower AM count
Along with optical and transmission electron microscopy of cells sedimented by centrifuging the BALF, we examined the topography of the BALF cell surfaces with the help of semi-contact atomic force microscopy reputed as a unique technique allowing one to obtain 3D visualizations of the surface topography of biological objects with a nanometric spatial resolution
Summary
Nanoparticles (NPs) of metals and of their oxides are of special interest for industrial toxicologists because, along with engineered metal-containing NPs, there exists usually a substantial fraction of nanoscale (“ultrafine”) particles of the same or chemically close substances within the particle size distribution of condensation aerosols generated by arc-welding and metallurgical technologies. We studied cells of bronchoalveolar lavage fluid (BALF) obtained 24 h after intratracheal (i.t.) instillation to rats of small doses of nanoparticles (NPs) or of their micrometric counterparts (MPs) using optical (OM), transmission electron (TEM) and semi-contact atomic force (sc-AFM) microscopy In this way, the i.t. model provides natural objects for studying the phagocytic activity of pulmonary (alveolar) macrophages and polymorphonuclear leukocytes, as well as intracellular localization of NPs engulfed by them and ultrastructural damage caused to the cell by internalized NPs. The results obtained might be regarded as comparable with those obtained by other researchers in experiments on cell cultures, but we maintain that the former provided a valuable addition to in vitro assessments of particle cytotoxicity even if only because in vivo interaction between cells and particles occurs in a microenvironment which is not reproducible by any artificial culture medium. For the purpose of demonstrating to what extent they could be related to copper-containing NPs as well, we present in this article the data of a similar study involving specially prepared copper-containing ultrafine particles modeling various fractions of the above-mentioned industrial aerosols formed during copper smelting and casting
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