Inflammatory response of mice following inhalation exposure to iron and copper nanoparticles

We examined pulmonary inflammatory responses of mice following whole-body inhalation exposure to copper and iron nanoparticles in acute and sub-acute studies. Concentrations for sub-acute copper and iron exposures were 3.6 mg m(-3). No significant pathology was found following acute exposure. Immediately following sub-acute exposure, both iron-and copper-exposed mice showed increased inflammation compared to sentinels. Copper nanoparticle-exposed mice had significantly higher lavage cytokines as well as perivasculitis and alveolitis. Three weeks post-exposure, all inflammatory markers decreased for iron nanoparticle-exposed mice, however, some remained elevated for copper-exposed mice. At biologically relevant pHs, in vitro studies showed that copper nanoparticles displayed a greater propensity for dissolution compared to iron. We conclude that the presence of dissolved ions, the concomitant formation of smaller nanoparticles and the absence of particles in stained lung sections immediately postexposure (inferring either translocation or more dispersed aerosol distribution) contributed to the increased inflammation observed in copper nanoparticle-exposed mice.