Theaflavin alleviates oxidative injury and atherosclerosis progress via activating microRNA‐24‐mediated Nrf2/HO‐1 signal

Theaflavin (TF) in black tea has been shown to have significant antioxidant and anti-inflammatory capacity; however, the effects and the underlying mechanism of TF on atherosclerosis (AS) remain unclear. Herein, we investigated the effects and the potential mechanism of TF on AS progression in vivo and in vitro. ApoE-/- mice were administrated with high fat diet (HFD) or HFD + TF (5 or 10 mg, i.g.) for 12 weeks. The results indicated that TF administration effectively decreases the serum lipid levels and the production of MDA in HFD-fed mice. Meanwhile, TF promotes the activities of antioxidant enzymes (SOD, CAT, and GSH-Px) and inhibits the formation of atherosclerotic plaque and the process of histological alterations in the aorta. In vitro, TF pretreatment could protect against cholesterol-induced oxidative injuries in HUVEC cells, decreasing the level of ROS and MDA, maintaining the activities of antioxidant enzymes. Further study revealed that TF upregulates Nrf2/HO-1 signaling pathway in vascular endothelial cells. Moreover, TF increases the level of microRNA-24 (miR-24), and miR-24 inhibition markedly compromises TF-induced Nrf2 activation and protective effects. In conclusion, the present study indicated that theaflavins may achieve the anti-atherosclerotic effect via activating miR-24-mediated Nrf2/HO-1 signaling pathway.