title: High density lipoprotein 3 inhibits oxidized low density lipoprotein-induced apoptosis via promoting cholesterol efflux in RAW264.7 cells.
abstract: OBJECTIVE
  To investigate the protective effect of high density lipoprotein 3 (HDL3) on oxidized low density lipoprotein (ox-LDL)-induced apoptosis in RAW264.7 cells.
  
  
  METHODS
  RAW264.7 cells were exposed to 50 mg/L ox-LDL for various durations up to 48 h, and apoptosis was detected using Hoechst 33258 staining and flow cytometric analysis. Total cholesterol levels were detected by high performance liquid chromatography, cholesterol efflux was determined by Tritium labeling, and the cellular lipid droplets were assayed by oil red O staining.
  
  
  RESULTS
  Treatment with 50 mg/L ox-LDL for 12, 24, and 48 h increased the apoptotic rate of RAW264.7 cells in a time-dependent manner. The peak apoptotic rate (47.7%) was observed after 48 h incubation. HDL3 at various concentrations (50 mg/L, 100 mg/L, and 200 mg/L) inhibited the ox-LDL (50 mg/L for 48 h)-mediated apoptosis that was accompanied by an increased rate of intracellular cholesterol efflux, and decreased total cholesterol levels in cells in a concentration-dependent manner. Blockage of cholesterol efflux by brefeldin decreased the protective effect of HDL3 on ox-LDL-induced apoptosis. Increase of the cholesterol efflux effected by another cholesterol acceptor,beta-cyclodextrin, led to a dramatic decrease in the apoptotic rate of cells.
  
  
  CONCLUSIONS
  HDL3 antagonizes ox-LDL-induced apoptosis in RAW264.7 cells, through reducing the accumulation of toxic cholesterol.
authors.affiliation: Division of Pharmacoproteomics, Institute of Pharmacy and Pharmacology, Nanhua University, Hengyang 421001, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Jiang
authors.forename: Peng-ke
authors.initials: PK
authors.lastname: Yan
authors.forename: Jian-xiong
authors.initials: JX
authors.lastname: Chen
authors.forename: Bing-yang
authors.initials: BY
authors.lastname: Zhu
authors.forename: Xiao-yong
authors.initials: XY
authors.lastname: Lei
authors.forename: Wei-dong
authors.initials: WD
authors.lastname: Yin
authors.forename: Duan-fang
authors.initials: DF
authors.lastname: Liao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D020126:Brefeldin A / Q000494:pharmacology; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000494:pharmacology*; D053440:Lipoproteins, HDL3; D008077:Lipoproteins, LDL / Q000037:antagonists & inhibitors*; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D051379:Mice; D010084:Oxidation-Reduction; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D008075:Lipoproteins, HDL; D053440:Lipoproteins, HDL3; D008077:Lipoproteins, LDL; D047392:beta-Cyclodextrins; C099252:oxidized low density lipoprotein; D020126:Brefeldin A; D002784:Cholesterol