Single-wall carbon nanotube-induced airway hyperresponsiveness in rats and a postulated mechanism of action

Inflammatory responses, oxidative stress, as well as fibrosis in lungs induced by a type of nano-sized carbon nanotubes (single-walled carbon nanotubes (SWCNTs)) have been investigated. However, studies examining the effects of SWCNTs on airway hyperresponsiveness (AHR) are not so numerous. We examined the effects of pulmonary exposure to SWCNTs on AHR and sought the underlying molecular mechanisms. Wistar rats were divided into four experimental groups and repeatedly administered vehicle or 0.02, 0.20 and 2.00 mg kg(-1) body weight SWCNTs through the intratracheal route. We found that 0.20 and 2.00 mg kg(-1) body weight SWCNTs in rats caused significant exacerbation of AHR. SWCNTs also amplified the lung protein levels of T helper 2 cytokines, immunoglobulin production in serum, profiles of immune cells in lungs, and levels of oxidative stress-related biomarkers in the airways, and exhibited airway remodelling. These results suggest that SWCNTs can exacerbate AHR in rats by enhancing airway inflammation and pulmonary oxidative stress.