Aortic Oxidative Stress, Inflammation and DNA Damage Following Pulmonary Exposure to Cerium Oxide Nanoparticles in a Rat Model of Vascular Injury

Pulmonary exposure to cerium oxide nanoparticles (CeO(2) NPs) can occur either at the workplace, or due to their release in the environment. Inhaled CeO(2) NPs are known to cross the alveolar–capillary barrier and reach various parts of the body, including the vasculature. The anticancer drug cisplatin (CP) causes vascular damage. However, the effects CeO(2) NPs on vascular homeostasis in a rat model of CP-induced vascular injury remain unclear. Here, we assessed the impact and underlying mechanism of pulmonary exposure to CeO(2) NPs on aorta in rats given a single intraperitoneal injection of cisplatin (CP, 6 mg/kg) to induce vascular damage. Six days later, the rats were intratracheally instilled with either CeO(2) NPs (1 mg/kg) or saline (control), and various variables were studied 24 h thereafter in the aortic tissue. The concentration of reduced glutathione and the activity of catalase were significantly increased in the CP + CeO(2) NPs group compared with both the CP + saline and the CeO(2) NPs groups. The activity of superoxide dismutase was significantly decreased in the CP + CeO(2) NPs group compared with both the CP + saline and CeO(2) NPs groups. The expression of nuclear factor erythroid-derived 2-like 2 (Nrf2) by the nuclei of smooth muscles and endocardial cells assessed by immunohistochemistry was significantly augmented in CeO(2) NPs versus saline, in CP + saline versus saline, and in CP + CeO(2) NPs versus CeO(2) NPs. Moreover, the concentrations of total nitric oxide, lipid peroxidation and 8-hydroxy-2-deoxyguanosine were significantly elevated in the CP + CeO(2) NPs group compared with both the CP + saline and the CeO(2) NPs groups. Similarly, compared with both the CP + saline and CeO(2) NPs groups, the combination of CP and CeO(2) NPs significantly elevated the concentrations of interleukin-6 and tumour necrosis factor-α. Additionally, aortic DNA damage assessed by Comet assay was significantly increased in CeO(2) NPs compared with saline, and in CP + saline versus saline, and all these effects were significantly aggravated by the combination of CP and CeO(2) NPs. We conclude that pulmonary exposure to CeO(2) NPs aggravates vascular toxicity in animal model of vascular injury through mechanisms involving oxidative stress, Nrf2 expression, inflammation and DNA damage.