Baicalein alleviates palmitic acid-induced endothelial cell dysfunction via inhibiting endoplasmic reticulum stress

Abstract

OBJECTIVE: Endothelial cells play a critical role in maintaining vascular function and kinetic homeostasis, but excessive accumulation of palmitic acid (PA) may lead to endoplasmic reticulum stress and trigger endothelial cell dysfunction. Baicalin (BCL), a natural plant extract, has received widespread attention for its biological activities in anti-inflammation and anti-oxidative stress. However, the mechanism of BCL on PA-induced endothelial cell dysfunction is unclear. Therefore, the aim of this study was to investigate whether BCL could inhibit PA-induced endoplasmic reticulum stress and thus attenuate endothelial cell dysfunction. METHODS: Human umbilical vein endothelial cells (HUVECs) were divided into Control, PA, PA + BCL-10 μM, PA + BCL-20 μM, and PA + BCL-50 μM groups. The PA group was treated with PA (200 μM), while the PA + BCL groups were co-treated with different concentrations of BCL (10 μM, 20 μM, 50 μM) for 24 hours. Cell viability was detected by MTT. Cell migration ability was determined by Transwell assay, apoptosis level by flow cytometry, and tube formation ability by tube formation assay. Finally, the levels of apoptosis-related proteins (Bax, Bcl-2, and cleaved caspase-3) and angiogenesis-related proteins (VEGFA and FGF2) were detected by western blot, MMP-9, as well as the protein levels of endoplasmic reticulum stress biomarkers (GRP78, CHOP, PERK, and ATF4). RESULTS: The results at the cellular level showed that cell viability, migration ability and tube formation ability of PA-induced HUVECs were significantly reduced, while apoptosis level was significantly increased. However, administration of different concentrations of BCL significantly enhanced PA-induced cell viability, migration ability and tube formation ability of HUVECs while inhibiting apoptosis. The results of protein levels showed that the protein levels of Bax and cleaved caspase-3 were observably up-regulated in the cells of the PA group, while the protein level of Bcl-2 was significantly down-regulated; compared with the PA group, the protein levels of Bax and cleaved caspase-3 were much lower and the Bcl-2 protein level was much higher in the PA + BCL group. Additionally, the protein levels of VEGFA, FGF2 and MMP-9 were raised and those of GRP78, CHOP, PERK and ATF4 were lowered in the PA + BCL group of cells in a concentration-dependent manner. CONCLUSION: BCL significantly attenuates PA-induced endothelial cell dysfunction by inhibiting endoplasmic reticulum stress.