The toxic effects of single-walled carbon nanotubes are linked to the phagocytic ability of cells

Abstract

Phagocytosis is thought to be the most important internalization pathway for single-walled carbon nanotubes (SWCNTs) with a length of 1 μm or more and thus for SWCNT related toxicity. In this paper we therefore focused on the effect of SWCNT exposure on cytotoxicity, cell cycle, gene expression and cytokine release in the non-phagocytic A549 lung epithelial cell line and phagocytic human monocyte derived THP-1 and mouse J774 macrophages. The J774 cell line was found to be the most efficient at taking up SWCNTs and its phagocytic ability was 4 times higher than for THP-1. The effect of SWCNT exposure on the different cell lines significantly increased with their ability to take up SWCNTs (J774 > THP-1 > A549). In contrast to A549 and THP-1, exposure to 10 μg mL⁻¹ SWCNTs affected all the investigated parameters in J774 and led to, e.g., changed cell morphology, reduced cell viability, induction of necrosis, reduced phagocytic ability, increased ROS levels, induction of regulation of gene expression and cytokine release. In contrast, apoptosis was not induced. Our results strongly suggest that the toxic effects of SWCNTs are linked to the phagocytic activity of cells and suggest that there might be a difference in how human and mouse macrophages react to SWCNT exposure.