Carbon nanotubes provoke inflammation by inducing the pro-inflammatory genes IL-1β and IL-6

Carbon nanotubes (CNTs) are largely produced and widely used because of their novel features, and the annual yield is expected to increase dramatically in the near future. Meanwhile, adverse health influences from exposure to CNTs are widely concerned, partially due to their asbestoid characteristics. In the current study, to assess the inflammatory responses and related mechanisms, we established a mouse model of chronic exposure to CNTs using intraperitoneal injection of single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). Our results demonstrated the fibre-like pathogenic behaviors of CNTs, reflected by increased total protein content in the lavageate from peritoneal cavities and increased serum levels of inflammatory cytokines, IL-1β and IL-6. The pro-inflammatory effects of CNTs were further validated with exposure to in vitro cultured monocyte-macrophage cells, J774A.1, as SWNTs and MWNTs significantly increased the expression levels of pro-inflammatory genes IL-1β and IL-6. Collectively, our data demonstrate that SWNTs and MWNTs provoke considerable inflammation presumably due to their fibre-like shape, and further confirm the length- and size-related structure-activity relationship for CNTs in stimulating inflammatory responses.