Investigation of the pulmonary bioactivity of double-walled carbon nanotubes.
Sager-TM; Wolfarth-MG; Porter-DW; Steinbach-T
Toxicologist 2013 Mar; 132(1):97
Nanotechnology is one of the world's most promising new technologies. In turn, carbon nanotube production is estimated to reach into the millions of tons within the decade. Our laboratory has previously established that exposure to multi-walled carbon nanotubes (MWCNT) causes lung inflammation and fibrosis in mice after pharyngeal exposure. However, the bioactivity of double-walled carbon nanotubes (DWCNT) has not been determined. In this study we explored the hypothesis that DWCNT would promote pulmonary toxicity by analyzing the pulmonary bioactivity of the DWCNT. To test this hypothesis, male mice (C57BL/6J) were given a single dose of one of the following by pharyngeal aspiration: 1) 0.9% saline with 0.3% (w/v) carboxymethyl cellulose (CMC; vehicle control), or 2) DWCNT (0-40 microg/mouse) suspended in vehicle [0.9% saline with 0.3% (w/v) CMC]. Whole lung lavage (WLL) was conducted at 1 and 7 days post-exposure. Lungs of non-lavaged animals were also collected and processed for histopathologic analysis at 7 and 56 days post-exposure. The results show the DWCNT exposure caused a dose-dependent increase in WLL polymorphonuclear leukocytes, indicating that DWCNT exposure initiates pulmonary inflammation. DWCNT exposure also caused a dose-dependent increase in LDH activity as well as albumin levels in WLL fluid, indicating that DWCNT exposure promotes cytotoxicity as well as decreases in the integrity of the blood-gas barrier in the lung. Also, at 56 days post-exposure, the presence of fibrosis was noted in the highest dose exposure group (40 microg/mouse). In conclusion, this study provides insight into the previously uninvestigated pulmonary bioactivity of DWCNT exposure. The results confirm that DWCNT exposure does promote inflammation and fibrosis in the lung. The results also indicate that DWCNT have a similar pulmonary bioactivity as the previously studied MWCNT.
Toxicology; Nanotechnology; Laboratory-animals; Laboratory-techniques; Exposure-assessment; Exposure-levels; Pulmonary-function; Pulmonary-system; Lung-function; Dose-response; Histopathology; Pulmonary-disorders; Lung-fibrosis; Lung-disorders; Bioactivation; Immune-reaction; Leukocytes; Cellulose-fibers; Cytotoxicity
The Toxicologist. Society of Toxicology 52nd Annual Meeting and ToxExpo, March 10-14, 2013, San Antonio, Texas