These studies are being conducted to evaluate potential cardiovascular toxicity of subchronic inhalation exposure to Fullerene C60 in animal models using molecular and biochemical analysis of cardiovascular tissue and blood samples. The findings will be correlated with the histopathological, particle distribution, and blood chemistry results being obtained in concurrent NTP studies. The cardiovascular effects of subchronic inhalation exposure of B6C3F1 mice to C60 particles (diameter 1 μm at concentrations 0, 2, 10, 30 mg/m3;and diameter 0.05 μm at concentrations 0, 0.5 and 2 mg/m3) were evaluated. The initial screening for cardiovascular toxicity was conducted applying a custom-designed TaqMan array for genes known to play an important role in the mechanisms of atherosclerosis such as inflammation, oxidative stress, and coagulation. Changes were observed on expression of several genes related to stress response, including c-fos, and heat shock protein (hsps) 25, 70, and 90 in the aortas of the exposed mice independent of the size of the particles. These findings were confirmed by a real-time RT-PCR. Furthermore, the aorta samples were analyzed with heat shock protein SuperArray and several members of the family were found to be expressed in the C60-treated animals. Similar results were found in the hearts of these animals. The gene expression of the hsps was dose dependent. Hsps are incremental in triggering many autoimmune/chronic inflammatory diseases. In this regard, it has been suggested a multifaceted role for hsps in atherosclerosis. For example, it has been reported that the expression of hsps is upregulated very early at lesion-prone sites in the aortas of young apoE-/- mice. Thus, fullerene exposure of wild type mice, not prone to develop atherosclerosis, resulted in a cardiovascular stress response which may provide a predisposition to atherogenesis.
