Evaluation of the in vitro and in vivo proinflammatory activities of gold (+) and gold (-) nanoparticles

The aim of this study was to determine potential effects of gold (+) and gold (-) nanoparticles, AuNP(+) and AuNP(-), on neutrophil biology. Freshly isolated human neutrophils were used for the in vitro aspects and CD-1 mice were used in the in vivo murine air pouch model of acute neutrophilic inflammation. Human neutrophils were treated with the indicated concentrations of AuNP(+) or AuNP(-) in vitro and mice received 100 or 500 A mu g/ml AuNP(+) or AuNP(-) into air pouches. Cellular uptake of AuNP by neutrophils was confirmed by transmission electron microscopy and the ability of the NP to modulate apoptosis, gelatinase activity, and chemokine production and chemotaxis was determined by cytology, zymography, ELISArray, antibody array, and ELISA and by a micro-chemotaxis chamber, respectively. In vivo, exudates were harvested after 6 h to determine the leukocyte infiltration to detect the production of several cytokines by an antibody array approach and ELISA. One-way analysis of variance was used for statistical analysis. AuNP possess proinflammatory activities in vitro and induce mainly a neutrophil influx in vivo, albeit at different degrees. AuNP(+) and AuNP(-) should be added as new candidates into a growing list of NP having proinflammatory activities by themselves.