Cardiovascular effects of pulmonary exposure to single-wall carbon nanotubes.
BACKGROUND
Engineered nanosized materials, such as single-wall carbon nanotubes (SWCNT), are emerging as technologically important in different industries.


OBJECTIVE
The unique physical characteristics and the pulmonary toxicity of SWCNTs raised concerns that respiratory exposure to these materials may be associated with cardiovascular adverse effects.


METHODS
In these studies we evaluated aortic mitochondrial alterations by oxidative stress assays, including quantitative polymerase chain reaction of mitochondrial (mt) DNA and plaque formation by morphometric analysis in mice exposed to SWCNTs.


RESULTS
A single intrapharyngeal instillation of SWCNTs induced activation of heme oxygenase-1 (HO-1), a marker of oxidative insults, in lung, aorta, and heart tissue in HO-1 reporter transgenic mice. Furthermore, we found that C57BL/6 mice, exposed to SWCNT (10 and 40 mug/mouse), developed aortic mtDNA damage at 7, 28, and 60 days after exposure. mtDNA damage was accompanied by changes in aortic mitochondrial glutathione and protein carbonyl levels. Because these modifications have been related to cardiovascular diseases, we evaluated whether repeated exposure to SWCNTs (20 mug/mouse once every other week for 8 weeks) stimulates the progression of atherosclerosis in ApoE(-/-) transgenic mice. Although SWCNT exposure did not modify the lipid profiles of these mice, it resulted in accelerated plaque formation in ApoE(-/-) mice fed an atherogenic diet. Plaque areas in the aortas, measured by the en face method, and in the brachiocephalic arteries, measured histopathologically, were significantly increased in the SWCNT-treated mice. This response was accompanied by increased mtDNA damage but not inflammation.


CONCLUSIONS
Taken together, the findings are of sufficient significance to warrant further studies to evaluate the systemic effects of SWCNT under workplace or environmental exposure paradigms.
Li
Zheng
Z
Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA.
Hulderman
Tracy
T
Salmen
Rebecca
R
Chapman
Rebecca
R
Leonard
Stephen S
SS
Young
Shih-Houng
SH
Shvedova
Anna
A
Luster
Michael I
MI
Simeonova
Petia P
PP
D000280:Administration, Inhalation; D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics; D050197:Atherosclerosis / Q000378:metabolism / Q000473:pathology*; D016122:Brachiocephalic Trunk / Q000187:drug effects* / Q000473:pathology; D004249:DNA Damage; D004272:DNA, Mitochondrial / Q000187:drug effects* / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000235:genetics; D008168:Lung / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009206:Myocardium / Q000378:metabolism; D037742:Nanotubes, Carbon / Q000633:toxicity*
D001057:Apolipoproteins E; D004272:DNA, Mitochondrial; D037742:Nanotubes, Carbon; D051547:Heme Oxygenase-1; D005978:Glutathione; D019803:Glutathione Disulfide