Bo Hui1, Xuwei Hou2, Ruhui Liu3, Xiao-Hong Liu4, Zhaohui Hu5. 1. Department of Cardiology, Qingdao Municipal Hospital of Qingdao University, Qingdao, 266071, China. 2. School of Medicine, the University of Missouri, Columbia, MO 65201, USA. 3. Department of Cardiovascular Diseases, Tongji Hospital of Tongji University, Shanghai 200065, China. 4. Cardiovascular Department of Internal Medicine, Central Hospital of Karamay, Karamay 834000, Xinjiang Uyghur Autonomous Region, China. Electronic address: Lxh61666@sohu.com. 5. Department of Cardiovascular Diseases, Tongji Hospital of Tongji University, Shanghai 200065, China. Electronic address: 09008@tj.hospital.sh.cn.
Abstract
BACKGROUND: Gypenoside (GP) is the major bioactive constituent of G. pentaphyllum, a traditional Chinese medicine. It has been reported that GP can affect autophagy and lipid metabolism in cultured cells. We hypothesize that GP can inhibit foam cell formation in cultured macrophages through autophagy modulation. METHODS: THP1 cells were cultured and treated with oxidized low-density lipoprotein (ox-LDL), followed by GP treatment at different concentrations. The autophagy flux was evaluated using western blot and confocal microscope analyses. The ox-LDL uptake and foam cell formation abilities were measured. RESULTS: We found that ox-LDL impaired the autophagy flux in the cultured macrophages, indicated by a significant reduction of LC3-II and autophagosome puncta quantification, as well as an accumulation of p62 proteins. GP treatment, however, dose-dependently restored the autophagy flux impaired by ox-LDL and reduced the ox-LDL uptake and foam cell transformation from THP1 cells, which can be alleviated, or exacerbated, by modulation of autophagy status using autophagy enhancer or inhibitor. Coimmunoprecipitation assays showed that GP up-regulated Srit1 and FOXO1 expression and enhanced their direct interaction, and thus contributed to the regulation of autophagy. CONCLUSION: GP inhibits ox-LDL uptake and foam cell formation through enhancing Sirt1-FOXO1 mediated autophagy flux restoration, suggesting this compound has therapeutic potential for atherosclerosis.
BACKGROUND: Gypenoside (GP) is the major bioactive constituent of G. pentaphyllum, a traditional Chinese medicine. It has been reported that GP can affect autophagy and lipid metabolism in cultured cells. We hypothesize that GP can inhibit foam cell formation in cultured macrophages through autophagy modulation. METHODS:THP1 cells were cultured and treated with oxidized low-density lipoprotein (ox-LDL), followed by GP treatment at different concentrations. The autophagy flux was evaluated using western blot and confocal microscope analyses. The ox-LDL uptake and foam cell formation abilities were measured. RESULTS: We found that ox-LDL impaired the autophagy flux in the cultured macrophages, indicated by a significant reduction of LC3-II and autophagosome puncta quantification, as well as an accumulation of p62 proteins. GP treatment, however, dose-dependently restored the autophagy flux impaired by ox-LDL and reduced the ox-LDL uptake and foam cell transformation from THP1 cells, which can be alleviated, or exacerbated, by modulation of autophagy status using autophagy enhancer or inhibitor. Coimmunoprecipitation assays showed that GP up-regulated Srit1 and FOXO1 expression and enhanced their direct interaction, and thus contributed to the regulation of autophagy. CONCLUSION: GP inhibits ox-LDL uptake and foam cell formation through enhancing Sirt1-FOXO1 mediated autophagy flux restoration, suggesting this compound has therapeutic potential for atherosclerosis.