[The oxLDL/β2GPI/anti-β2GPI antibody complex induces apoptosis of human umbilical vein endothelial cells by promoting the production of reactive oxygen species].

Objective To investigate the effect of oxidative low-density lipoprotein/β2 glycoprotein I/anti-β2 glycoprotein I antibody (oxLDL/β2GPI/αβ2GPIAb) complex on the apoptosis of human umbilical vein endothelial cells (HUVECs) and the role of reactive oxygen species (ROS) in the process. Methods HUVECs were stimulated by β2GPI, aβ2GPIAb, β2GPI/aβ2GPIAb complex, oxLDL, oxLDL/β2GPI complex, oxLDL/β2GPI/rabbit (R)-IgG complex, and oxLDL/β2GPI/aβ2GPIAb complex. The protein levels of apoptosis-related proteins including BAX, Bcl2 and cleaved caspase-3 (c-caspase-3) were detected by Western blot analysis. Annexin V-FITC/PI double labeling combined with flow cytometry was performed to detect apoptosis rate; dichlorofluorescein diacetate (DCFH-DA) labeling combined with flow cytometry was used to detect ROS level. And the effect of each treatment on cell viability was analyzed by CCK-8 assay. The changes of mean fluorescence intensity of ROS and the apoptosis of HUVECs induced by oxLDL/β2GPI/aβ2GPIAb complex were observed by the pretreatment with antioxidant apocynin or diphenylphosphonium iodide (DPI). Results The oxLDL/β2GPI/aβ2GPIAb complex significantly reduced the viability of HUVECs, increased the expression of BAX and cleaved caspase-3 protein, decreased the level of Bcl2 protein, and promoted the apoptosis of HUVECs. In addition, oxLDL/β2GPI/aβ2GPIAb complex induced an increase of ROS level during apoptosis, which could be attenuated by antioxidants. The effect of complex-induced apoptosis could also be reversed to some extent by antioxidants. Conclusion The oxLDL/β2GPI/aβ2GPIAb complex can induce the apoptosis in HUVECs by increasing ROS.