The Role of NADPH Oxidase in Multi-Walled Carbon Nanotubes-Induced Oxidative Stress and Cytotoxicity in Human Macrophages

Abstract

Recent studies suggest reactive oxygen species (ROS) induced in mammalian cells exposed to multi-walled carbon nanotubes (MWCNTs) could mediate the cytotoxicity. This study was conducted to determine the mechanisms responsible for MWCNTs-induced ROS production in human primary macrophages. Our results showed that superoxide levels were significantly increased in a time-dependent manner in blood monocyte-derived macrophages treated with 100 microg/ml MWCNTs for 12 h. Concomitantly, MWCNTs induced membrane translocation of the NADPH oxidase subunits p47phox and p67phox, a signature event for NADPH oxidase activation. Pre-incubation with apocynin, a selective inhibitor of NADPH oxidase, prevented both membrane translocation of p47phox and superoxide production. Treatment with MWCNTs also resulted in an increased cytotoxicity in human primary macrophages that was significantly attenuated by both apocynin and antioxidants. These findings demonstrate that MWCNTs activate NADPH oxidase in human macrophages, which may contribute to ROS generation in MWCNTs treated-macrophages.

In vivogenotoxicity evaluation of lung cells from Fischer 344 rats following 28 days of inhalation exposure to MWCNTs, plus 28 days and 90 days post-exposure

“…It has been previously reported that genotoxicity effects can result from the direct interaction of nanoparticles with genetic material or secondary damage resulting from particle-induced reactive oxygen species production (Kisin et al, 2011). According to the recent in vitro studies, SWCNTs and MWCNTs induce ROS production in mammalian cells (Sharma et al, 2007;Shvedova et al, 2003;Ye et al, 2009Ye et al, , 2011. In a previous in vivo 5-day inhalation study by the current authors, a 2.57 mm average tube length induced an increased concentration of intracellular H 2 O 2 with a similar trend of DNA damage (Kim et al, 2012b).…”

Lysosomal membrane permeabilization: Carbon nanohorn-induced reactive oxygen species generation and toxicity by this neglected mechanism

“…Because metal catalysts are not used in the production of CNHs, this possibility can be excluded. Ye et al (2011) found that MWNT could activate the NADPH oxidase in human macrophages, which may contribute to ROS generation. Sharma et al (2007) concluded that the mitochondria is not involved in SWNT induced ROS production and that SWNT induces oxidative stress by loss of antioxidants, but how does SWNT affect the antioxidants was still unclear.…”

“…Among these studies, most report that oxidative stress and the production of reactive oxygen species (ROS), which are involved in the apoptosis pathway (Cheng et al, 2011), are the major adverse effects mediated by carbon nanotubules (Ravichandran et al, 2009;Srivastava et al, 2011;Pacurari et al, 2008;Lacotte et al, 2008;Liu et al, 2013;Yang et al, 2009). Although some previous reports discussed ROS generation by carbon nanotubules (Kagan et al, 2006;Lacotte et al, 2008;Sharma et al, 2007;Pulskamp et al, 2007;Ye et al, 2011), a detailed understanding of the mechanisms and pathways involved is currently lacking.…”

Effects of multiwalled carbon nanotubes and triclocarban on several eukaryotic cell lines: elucidating cytotoxicity, endocrine disruption, and reactive oxygen species generation

“…This might be the reason why other studies in which ROS was measured after more than 4 h exposure to CNT showed inconsistent results [50,117-119]. Several studies [112,120] concluded that cytotoxicity can be attributed to oxidative stress. Interestingly, no cytotoxic effect was found in this study in three different MWCNT-treated cells, although generation of ROS was observed in all cell lines used.…”