Chromogranin B Protects Human Umbilical Endothelial Cells against Oxidative Stress

Chromogranin B (CgB) is involved in the control of the cardiovascular system through the regulation of catecholamine release. Whether CgB can exert direct actions on the endothelium has not yet been clarified. Here, we aimed to investigate the effects of CgB on cell viability, mitochondrial membrane potential, reactive oxygen species (ROS), glutathione (GSH), nitric oxide (NO) release, and the cytosolic calcium concentration ([Ca²⁺]c) in human vascular endothelial cells (HUVECs) cultured under both physiological and peroxidative conditions. In HUVECs, experiments were conducted to establish the proper concentration and timing of CgB stimulation. Thereafter, specific assays were used to evaluate the response of HUVECs cultured in physiologic or oxidative stress conditions to CgB in the presence or absence of β-adrenergic receptor agonists and antagonists and intracellular pathways blockers. Analysis of cell viability, mitochondrial membrane potential, and NO release revealed that CgB was able to cause increased effects in HUVECs cultured in physiological conditions. Additionally, the same analyses performed in HUVECs cultured with H₂O₂, showed protective effects exerted by CgB, which was also able to counteract ROS release and maintain GSH levels. Furthermore, CgB played a dual role on the [Ca²⁺]c depending on the physiological or peroxidative cell culturing conditions. In conclusion, our data provide new information about the direct role of CgB in the physiological regulation of endothelial function and highlight its potential as a protective agent against peroxidative conditions, such as those found in cardiovascular diseases.