title: Iron Together with Lipid Downregulates Protein Levels of Ceruloplasmin in Macrophages Associated with Rapid Foam Cell Formation.
abstract: OBJECTIVE
  Iron accumulation in foam cells was previously shown to be involved in atherogenesis. However, the mechanism for iron accumulation was not clarified. Ceruloplasmin (Cp) is an important factor in cellular iron efflux and was found to be downregulated in atherosclerotic plaques in our previous study. The current study is to investigate the role of Cp in atherosclerosis.
  
  
  METHODS
  We used RAW264.7 cells, a well-accepted cell model of atherosclerosis, which were treated with lipopolysaccharides (LPS), ferric ammonium citrate (FAC) or deferoxamine, and oxidized low density lipoprotein (ox-LDL) to detect the regulation of Cp and its influence in iron efflux and lipid accumulation using biochemical and histological assays.
  
  
  RESULTS
  Our results showed that the Cp protein level increased after 200-μM FAC treatment in LPS-activated RAW264.7 cells. Ox-LDL treatment (50 μg/ml) moderately reduced both mRNA and protein levels and ferroxidase activity of Cp (p＜0.05). No significant difference was observed in the expression of ferritin and ferroportin, two important iron-related proteins for iron storage and efflux, respectively, after ox-LDL treatment. However, co-treatment with ox-LDL and FAC drastically reduced the expression of Cp. Accordingly, the ferroxidase activities simultaneously decreased, whereas the protein levels of Ft and Fpn1 significantly increased, indicating further iron accumulation. Moreover, co-treatment with FAC and ox-LDL enhanced the accumulation of cholesterol compared with ox-LDL-only treatment to trigger apoptosis.
  
  
  CONCLUSIONS
  Our findings suggest that physiological interaction of iron and lipid obstructs iron efflux and accelerates the lipid accumulation in macrophages during foam cell formation, which implicates the role of iron in the pathology of atherosclerosis.
authors.affiliation: Department of Vascular Surgery, Drum Tower Clinical Medical College of Nanjing Medical University.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Jiajie
authors.initials: J
authors.lastname: Ji
authors.forename: Shuangying
authors.initials: S
authors.lastname: Hao
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.forename: Kuanyu
authors.initials: K
authors.lastname: Li
authors.forename: Tong
authors.initials: T
authors.lastname: Qiao
mesh_terms: D050197:Atherosclerosis / Q000473:pathology*; D015153:Blotting, Western; D002478:Cells, Cultured; D002570:Ceruloplasmin / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D005434:Flow Cytometry; D005487:Foam Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007501:Iron / Q000737:chemistry / Q000494:pharmacology*; D008055:Lipids / Q000737:chemistry / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D008055:Lipids; D012333:RNA, Messenger; D007501:Iron; D002570:Ceruloplasmin