Paclitaxel Attenuates Atherosclerosis by Suppressing Macrophage Ferroptosis and Improving Lipid Metabolism via the Sirt1/Nrf2/ <scp>GPX4</scp> Pathway

Atherosclerosis is a leading cause of cardiovascular disorders such as coronary heart disease, heart failure, and stroke. Ferroptosis, a novel type of cell death, plays an important role in atherosclerosis progression, especially macrophage ferroptosis. Paclitaxel (PTX) is an antiproliferative drug that has been developed in recent decades and is helpful in the treatment of atherosclerosis. However, the mechanism underlying the anti-atherosclerotic effects of PTX via inhibition of ferroptosis in macrophages has not been determined. This study aimed to investigate the effect of PTX on ferroptosis in macrophages and determine the underlying mechanism of action in atherosclerosis. In ApoE^-/- mice, an atherosclerosis model was established by feeding a high-fat diet (HFD) for 12 weeks. Then, ApoE^-/- mice were treated with PTX and Atorvastatin (positive) for 8 weeks. The effects of PTX on atherosclerosis pathology were evaluated using Oil Red O, Masson's trichrome, and hematoxylin-eosin (HE) staining. To confirm whether PTX inhibited macrophage ferroptosis through the Sirt1/Nrf2/GPX4 pathway, immunofluorescence co-staining was performed on GPX4 and CD68 (a macrophage marker). Western blotting was used to determine the protein expression levels of the Sirt1/Nrf2/GPX4 pathway and iron metabolism-related markers. The extent of lipid peroxidation and iron concentration was examined. In addition, we further investigated the potential mechanism of PTX by constructing an atherosclerosis model of RAW 264.7 cells induced by ox-low-density lipoprotein (LDL) in vitro. The mechanism through which PTX improves AS was further verified using Sirt1 inhibitors and the knockdown of Sirt1. In vivo studies have shown that PTX significantly improves atherosclerosis progression, which is characterized by reduced lipid deposition, cholesterol crystallization, and increased collagen. Further studies in vivo have shown that PTX inhibits macrophage ferroptosis by activating the Sirt1/Nrf2/GPX4 pathway, thereby effectively improving atherosclerosis. In vitro experiments revealed that PTX decreases reactive oxygen species (ROS) levels and lipid accumulation in ox-LDL-induced RAW 264.7 cells. Consistent with in vivo studies, PTX not only changed the iron content and iron metabolism-related markers in ox-LDL-induced RAW 264.7 but also activated the Sirt1/Nrf2/GPX4 pathway. Additionally, the use of Sirt1 inhibitors and the knockdown of Sirt1 identified the potential of PTX to inhibit macrophage ferroptosis by activating the Sirt1/Nrf2/GPX4 pathway. These findings suggest that PTX reduces atherosclerosis by suppressing macrophage ferroptosis and improving lipid metabolism through the activation of the Sirt1/Nrf2/GPX4 pathway and offers new perspectives on the possible application of PTX as a powerful atherosclerosis medication option.