Gamma Radiation-Induced Disruption of Cellular Junctions in HUVECs Is Mediated through Affecting MAPK/NF-κB Inflammatory Pathways

Abstract

Ionizing radiation-induced cardiovascular diseases (CVDs) have been well documented. However, the mechanisms of CVD genesis are still not fully understood. In this study, human umbilical vein endothelial cells (HUVECs) were exposed to gamma irradiation at different doses ranging from 0.2 Gy to 5 Gy. Cell viability, migration ability, permeability, oxidative and nitrosative stresses, inflammation, and nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) pathway activation were evaluated postirradiation. It was found that gamma irradiation at doses ranging from 0.5 Gy to 5 Gy inhibited the migration ability of HUVECs without any significant effects on cell viability at 6 h and 24 h postirradiation. The decreased transendothelial electrical resistance (TEER), increased permeability, and disruption of cellular junctions were observed in HUVECs after gamma irradiation accompanied by the lower levels of junction-related proteins such as ZO-1, occludin, vascular endothelial- (VE-) cadherin, and connexin 40. The enhanced oxidative and nitrosative stresses, e.g., ROS and NO2- levels and inflammatory cytokines IL-6 and TNF-α were demonstrated in HUVECs after gamma irradiation. Western blot results showed that protein levels of mitogen-activated protein kinase (MAPK) pathway molecules p38, p53, p21, and p27 increased after gamma irradiation, which further induced the activation of the NF-κB pathway. BAY 11-7085, an inhibitor of NF-κB activation, was demonstrated to partially block the effects of gamma radiation in HUVECs examined by TEER and FITC-dextran permeability assay. We therefore concluded that the gamma irradiation-induced disruption of cellular junctions in HUVECs was through the inflammatory MAPK/NF-κB signaling pathway.