Cytokine responses of human lung cells (BEAS-2B) treated with micron-sized and nanoparticles of metal oxides compared to soil dusts

<p>Abstract</p> <p>Background</p> <p>The induction of cytokines by airway cells <it>in vitro </it>has been widely used to assess the effects of ambient and occupational particles. This study measured cytotoxicity and the release of the proinflammatory cytokines IL-6 and IL-8 by human bronchial epithelial cells treated with manufactured nano- and micron-sized particles of Al₂O₃, CeO₂, Fe₂O₃, NiO, SiO₂, and TiO₂, with soil-derived particles from fugitive dust sources, and with the positive controls LPS, TNF-α, and VOSO₄.</p> <p>Results</p> <p>The nano-sized particles were not consistently more potent than an equal mass of micron-sized particles of the same nominal composition for the induction of IL-6 and IL-8 secretion in the <it>in vitro </it>models used in this study. The manufactured pure oxides were much less potent than natural PM_2.5particles derived from soil dust, and the cells were highly responsive to the positive controls. The nano-sized particles in the media caused artifacts in the measurement of IL-6 by ELISA due to adsorption of the cytokine on the high-surface-area particles. The potency for inducing IL-6 secretion by BEAS-2B cells did not correlate with the generation of reactive oxygen species in cell-free media.</p> <p>Conclusion</p> <p>Direct comparisons of manufactured metal oxide nanoparticles and previously studied types of particles and surrogate proinflammatory agonists showed that the metal oxide particles have low potency to induce IL-6 secretion in BEAS-2B cells. Particle artifacts from non-biological effects need to be considered in experiments of this type, and the limitations inherent in cell culture studies must be considered when interpreting <it>in vitro </it>results. This study suggests that manufactured metal oxide nanoparticles are not highly toxic to lung cells compared to environmental particles.</p>