Journal of Nanomedicine & Nanotechnology

Modulatory activity of TiO2, CeO2 and ZnO on human neutrophil degranulation

3^rd International Conference on Nanotek & Expo

December 02-04, 2013 Hampton Inn Tropicana, Las Vegas, NV, USA

Kim Babin et Denis Girard

Accepted Abstracts: J Nanomed Nanotechnol

Abstract:

Background: Nanoparticles (NPs) are used in a vast array of applications, including personal products (sunscreens, textiles, cosmetics, etc.), household commodities (e.g. components of paints, carpets, etc.) food and in medicine. Because the number of products containing NPs increased rapidly, it is clear that humans will be gradually ever more exposed to NPs. Therefore, the effect of NPs on human health needs to be determined. Recently, human neutrophils have been found to be targets to NP exposure. Knowing the importance of neutrophils in inflammation, investigating the ability of NPs to modulate neutrophil functions is an excellent way to evaluate potential nanotoxicity of a given NP. Degranulation is one of the most important functions exerted by neutrophils for the defense of an organism against an infection; it consists in a rapid release of potent degradation enzymes, several receptors involved in the recognition and ingestion of pathogens, etc. These molecules are localized in three different kinds of granules: azurophil, specific/ gelatinase and secretory granules. Objective: The objective of the present study was to determine if the three NPs, TiO 2 , CeO 2 , and ZnO can alter the degranulation process. Methods: Neutrophils were isolated from healthy volunteers and incubated in vitro with 100 μg/ml of TiO 2 , CeO 2 , or ZnO NP. The concentration of 100 μg/ml was selected according to previous preliminary experiments. Degranulation was assessed by flow cytometry, by monitoring cell surface expression of marker for each granules (CD63, CD66b and CD35 for azurophil, specific/ gelatinase and secretory granules, respectively). In addition, western blot experiments were conducted to identify proteins secreted from the granules into the extracellular milieu. Finally, zymography assay was used to determine enzymatic activity in the extracellular milieu allowing visualization of gelatine degradation by gelatinases contained in the specific/gelatinase granules. Results: The cell surface expression of CD66b was significantly increased by CeO 2 and TiO 2 while the expression of CD63 and CD35 was not significantly altered. The protein expression of myeloperoxidase (azurophil granules) and matrix metallopeptidase 9 (MMP9 or gelatinase B) (specific/gelatinase granules) was significantly increased by the three NPs. The protein expression of albumin was significantly increased by CeO 2 and TiO 2 but, although its expression was increased by ZnO, this was not significant. Zymography revealed that the enzymatic activity in the supernatant of CeO 2 and TiO 2 induced neutrophils was significantly increased, but not ZnO. Conclusion: We conclude that the three tested NPs can induce degranulation in human neutrophils. However, the cell surface expression of specific markers for each type of granules does not appear to be the best way for determining potential effect on degranulation, except for CD66b, since the results also correlate with the detection of the protein (gelatinase B) in the supernatants, as well as the gelatinase enzymatic activity detected by zymography