Abstract W P207: Association of Increased Expression of NOX4 With Susceptibility to Hypoxia-Induced ROS Overproduction and ICAM-1 and VCAM-1 Upregulation in Brain Microvascular Endothelial Cells

Abstract

Background and Purpose: NADPH oxidase 4 (NOX4) is the predominant source of reactive oxygen species (ROS) in the endothelial cells. It has been demonstrated that brain microvascular endothelial cells (BMECs) is more susceptible to stress-induced cellular responses compared with endothelial cells from other larger vessels. The aim of this study is to examine susceptibility to hypoxia-induced cellular reactions in BMECs compared with aortic endothelial cells (AECs) in terms of association of NOX4 expression with ROS production. Methods: Cultured bovine BMECs and AECs were incubated in the modular incubator chamber pre-filled with anoxic gas (95%N 2 /5% CO 2 ) at 37°C. Time course changes of ROS production, cell death occurrence, and mRNA expression of NOX4, ICAM-1, VCAM-1, HIF-1α, VEGF and GAPDH were examined in BMECs and AECs until 4 hours after hypoxia. ROS production, cell death occurrence, and mRNA expression were evaluated with DHE staining, Live/Dead cell kit, and RT-PCR, respectively. Results: Basal ROS production was significantly higher in BMECs than in AECs (p<0.01). After hypoxia ROS production and cell death were more prominently increased in BMECs compared with AECs with time. While expression levels and pattern of HIF-1α and VEGF were similar in the both cells, expression levels of NOX4, ICAM-1, and VCAM-1 were quite different in the both cells. While the expression levels of NOX4, ICAM-1, and VCAM-1 in AECs were very low at all the time points, those expression levels in BMECs were significantly higher at the basal condition (p<0.01) and were increased more at 2 hours and decreased at 4 hours after hypoxia. Conclusions: It was demonstrated in BMECs but not in AECs that NOX4 expression was high and increased more after hypoxia, which is consistent with the increase of ROS production and ICAM-1 and VCAM-1 expression. Increased expression of NOX4 is likely associated with susceptibility to hypoxia-induced ROS overproduction and ICAM-1 and VCAM-1 upregulation in BMECs.