Tianxiangdan suppresses foam cell formation by enhancing lipophagy and reduces the progression of atherosclerosis

The aim of this study is to assess the impact of Tianxiangdan (TXD) on lipophagy in foam cells and its underlying mechanism in treating atherosclerosis, particularly focusing on its efficacy in lowering blood lipids. In vivo, ApoE-/- atherosclerosis mouse models were established for group intervention. Blood lipid levels of the mice were measured, lipid deposition and autophagy levels in atherosclerotic plaques were assessed, and co-localization of lipid droplets and autophagosomes was examined. In vitro, human THP-1 cells were induced into macrophages and then transformed into foam cells using ox-LDL induction. Different intervention groups were established. Total cellular cholesterol (TC), free cholesterol (FC), and autophagy levels were assessed, while the morphology and distribution of lipid droplets and autophagosomes in cells were observed using transmission electron microscopy. Western blot analysis was performed to evaluate the expression levels of PI3K, Akt, mTOR, TFEB, LC3II/I, ULK1, ABCA1, and p62. TXD effectively lowers blood lipid levels in ApoE-/- atherosclerotic mice, enhances lipophagy, and reduces lipid accumulation in foam cells and arterial lipid plaques. It achieves this by suppressing the expression of p85, Akt, and mTOR, while activating downstream autophagy signals such as TFEB, LC3II/I, and ULK1. Additionally, TXD reduces the expression of p62 and enhances the expression of the cholesterol transport molecule ABCA1. Our findings indicate that TXD activates lipophagy via the PI3K/Akt/mTOR pathway, leading to a reduction in lipid deposition within foam cells and plaques, thereby mitigating atherosclerosis.