Protective Effects of Oxymatrine on Vascular Endothelial Cells from High-Glucose-Induced Cytotoxicity by Inhibiting the Expression of A2B Receptor.

Background/Aims: Diabetes mellitus (DM) has become an increasingly epidemic metabolic disease. Vascular endothelial cells play a key role in developing the cardiovascular complications of DM. The A(2B) receptor is expressed in vascular endothelial cells, and may help regulate the function of endothelial cells. The aim of this study was to investigate the protective effects of oxymatrine (OMT) on human umbilical vein endothelial cells (HUVECs) from high glucose-induced cytotoxicity. Methods: Homology modeling and molecular docking analysis were used to detect the binding sites between the adenosine A(2B) receptor and OMT. HUVECs were cultured with control (5.5 mM) or elevated glucose (22.2 mM) in the presence or absence of 3 mu M OMT or A(2B) siRNA for 3 days. The MTS cell viability assay was used to measure the toxicity of high glucose on HUVECs and the protective effect of OMT or A(2B) siRNA. The expression of the adenosine A(2B) receptor and CCL5 in HUVECs was detected with real-time quantitative PCR (qPCR) and Western blotting methods in each group. Levels of IL-1 beta and TNF-alpha were measured using an enzyme-linked immunosorbent assay (ELISA) kit, and the concentration of NO was detected with the nitrate reductase method. Monocyte chemotactic activity in each group was detected using Transwell chambers. Furthermore, the phosphorylation of p38 and ERK1/2 in each group was observed through the Western blotting method. Results: Homology modeling and molecular docking analysis showed that OMT contains well-fitted binding sites to the A(2B) receptor. After chronic culture at high glucose, the rate of cell viability was significantly lower than that of the control group. After co-treatment with OMT or A(2B) siRNA, cell viability was significantly increased compared with the high-glucose group. The results from real-time quantitative RT-PCR (qRT-PCR) and Western blotting indicated that high glucose could increase the expression of A(2B) receptors in HUVECs, an effect that was inhibited by OMT. In addition, the results revealed that the expression of CCL5, IL-1 beta and TNF-alpha was increased in the high-glucose group, and that the NO produced by HUVECs decreased due to hyperglycemia; however, co-culture with OMT or A(2B) siRNA abolished these effects. Meanwhile, the chemotaxis activity of monocytes to HUVECs cultured in high-glucose medium was enhanced 2.59-fold compared to the control cells. However, the inflammatory reactions in HUVECs were completely relieved by co-treatment with OMT or A(2B) siRNA. Moreover, the phosphorylation of p38 and ERK1/2 in HUVECs in the high-glucose group was significantly higher than that of the control group; these effects were reversed after co-treatment with OMT or A(2B) siRNA. Conclusion: OMT may protect the HUVECs from high glucose-induced cytotoxicity through inhibitting the expression of A(2B) receptor and inflammatory factors as well as decreasing the phosphorylation of p38 and ERK1/2. (c) 2018 The Author(s) Published by S. Karger AG, Basel