Zinc oxide nanoparticle-induced atherosclerotic alterations in vitro and in vivo

Engineered zinc oxide nanoparticles (ZnO-NPs) are currently being produced in high tonnage. Exposure to ZnO-NPs presents potential risks to cardiovascular system. Thus far, the toxicological effects of ZnO-NPs on cardiovascular system have not been well characterized. In this study, human coronary artery endothelial cells (HCAECs) were exposed to ZnO-NPs directly or indirectly using a transwell coculture system with human alveolar epithelial cell line A549 to mimic the lung/circulation interaction. It was shown that levels of proinflammatory mediators (interleukin-8 [IL-8] and tumor necrosis factor-alpha [TNF-alpha]) and biomarkers of atherosclerogenesis (heme oxygenase-1 [HO-1] and platelet endothelial cell adhesion molecules-1 [PECAM-1]) in the supernatants of culture media were significantly increased. Pretreatment of A549 cells on the apical side of the coculture system with the phagocytosis inhibitor cytochalasin B (CB) blocked ZnO-NP-induced HO-1 and PECAM-1 expression in HCAEC, indicating that endocytosis of ZnO-NPs by alveolar epithelial cells was involved in ZnO-NP-induced HO-1 or PECAM-1 expression in endothelial cells. Moreover, Wistar rats were intratracheally instilled with ZnO-NP suspension and high fat diet (positive control). ZnO-NP treatment induced lung and systemic inflammation, dyslipidemia, increased levels of serum HO-1 and PECAM-1, and aortic pathological damage. Taken together, exposure to ZnO-NPs could induce atherosclerotic alterations, which might involve phagocytosis of nanoparticles and inflammation in the lung.