Paeonol suppresses oxidized low-density lipoprotein induced endothelial cell apoptosis via activation of LOX-1/p38MAPK/NF-κB pathway.

Paeonol is an active compound isolated from traditional Chinese medicine, and has been shown to have anti-atherosclerosis, anti-inflammatory, antioxidant effects. The present investigation was undertaken to determine the suppression effects of paeonol on oxidized low-density lipoprotein (ox-LDL) induced endothelial cell line HUVEC apoptosis and to uncover some of the underlying mechanisms of these effects. Cell viability and lactate dehydrogenase (LDH) were measured to evaluate the cell injuries. Apoptosis was evaluated by Hoechst 33342 staining and flow cytometry. Intracellular reactive oxygen species (ROS) generation was detected by 2',7'-dichlorofluorescein diacetate (DCFH-DA). Real-time PCR was used to confirm the expression of LOX-1 mRNA. Western blotting was used to evaluate the protein expression of LOX-1 and Bcl-2, as well as caspase-3 cleavage, p38-mitogen-activated protein kinase (p38MAPK) phosphorylation. NF-κB nuclear translocation was detected by Western blotting and immunofluorescence. Caspase-3 activity was measured using a colorimetric protease assay kit. The results showed that ox-LDL significantly decreased cell viability and increased the LDH release, as well as the apoptotic rate (P<0.01). Pre-treatment of paeonol resulted in remarkable increase of cell viability, decrease of LDH release and cell apoptosis in a concentration-dependent manner. Besides, ox-LDL caused the up-regulation of LOX-1, the down-regulation of Bcl-2, the phosphorylation of p38MAPK, the translocation of NF-κB and the activation of caspase-3. Paeonol pre-treatment reversed these effects introduced by ox-LDL. Moreover, paeonol also showed its inhibition effects on ox-LDL induced ROS overproduction. These results indicate the preventive effects of paeonol on ox-LDL induced endothelial cell apoptosis. The effects might, at least partly, be obtained via inhibition of LOX-1-ROS- p38MAPK-NF-κB signaling pathway.