Exposure of single-walled carbon nanotubes impairs the functions of primarily cultured murine peritoneal macrophages

Abstract

It is increasingly important to understand the single-walled carbon nanotubes' (SWCNTs) immune response as their increasingly biomedical researches and applications. Macrophages and T cells play important roles in scavenging foreign materials and pathogens and regulating immune response. In this work, primarily cultured murine peritoneal macrophages and purified splenic T cells were utilised to determine the toxic effects of SWCNTs and acid-functionalised SWCNTs (AF-SWCNTs) on the immune system, especially on macrophage functions. Macrophages were exposed to 0–50 μg/ml of CNTs for 24 h and no significant cytotoxicity was found by live/dead and annexin-V-FITC/PI analyses. The TEM images revealed that AF-SWCNTs were engulfed mostly through phagocytosis and located in lysosomes of macrophages. Measurement of mitochondrial membrane potential and proteasome subunit gene expression demonstrated that 10 and 50 μg/ml AF-SWCNTs could damage mitochondrial function and proteasome formation in a concentration-dependent manner. Functional analyses revealed that the percentage of phagocytic cells were affected significantly by 20 μg/ml CNTs, and 5 μg/ml AF-SWCNTs inhibited the phagocytic efficiency of latex beads in macrophages. The accessory cell function was affected by both AF-SWCNTs and SWCNTs at concentrations of 10 and 50 μg/ml, respectively. Furthermore, AF-SWCNT biased naïve T-cell differentiation to Th1 type by inducing the production of IFN-γ and TNF, implying the potential risk of Th1-associated diseases (e.g. autoimmune diseases and inflammation) on AF-SWCNT exposure.

Keywords::

• Acid-functionalised single-walled carbon nanotubes
• macrophage functions
• Th1/Th2 differentiation
• lymphoproliferation
• gene expression

Acknowledgments

This work was supported by the National Basic Research Program of China (No. 2009CB421605, 2011CB936001), the National Natural Science Foundation of China (20807054, 20921063, 21077124, 21177138). The authors would like to thank the lab of Bio-imaging, the Institute of Biophysics for the TEM work and specifically Sun Lei and Liu Yanrong for their assistance in TEM sample preparation and photographing. Brief: SWCNTs impair macrophage functions.