Mangiferin alleviates hyperglycemia-induced endothelial impairment via Nrf2 signaling pathway

The regulation of angiogenesis by nuclear factor erythroid 2-related factor 2 (Nrf2), a master redox transcription factor, is well established. In the present study, we aimed to activate Nrf2 by mangiferin (MG) and investigate its potential to regulate angiogenesis under a hyperglycemic (HG) environment in human endothelial cells. The mRNA expression of Nrf2 and its downstream targets HO-1, SOD-1, and CAT were observed to be decreased at 72 h of HG (33.3 mM glucose) exposure, and was ameliorated in MG (24 h) pretreated endothelial cells. ROS generation was assessed using an DCFDA assay, where we found the ROS generated at HG exposure was quenched by MG in a dose-dependent manner. The angiogenic markers HIF-1α and VEGF were also decreased in HG-induced endothelial cells, which significantly increased in the cells pretreated with MG. In addition, we have observed substantially more closed tube network formation in MG pretreated cells, which was low in HG-induced endothelial cells. The cell migration potential was monitored using a scratch assay, where the cells activated by MG showed a more significant movement than those under HG stress. Furthermore, to understand the role of Nrf2 in regulating angiogenesis, we knocked out the Nrf2 using CRISPR/Cas9 in endothelial cells. The wild-type endothelial cells exposed to MG alone showed a cytoprotective effect under a hyperglycemic environment. Our findings collectively demonstrated that MG helps regulate impaired angiogenesis under a hyperglycemic environment through Nrf2 signaling.