title: Toxicity of oxidized phospholipids in cultured macrophages.
abstract: BACKGROUND
  The interactions of oxidized low-density lipoprotein (LDL) and macrophages are hallmarks in the development of atherosclerosis. The biological activities of the modified particle in these cells are due to the content of lipid oxidation products and apolipoprotein modification by oxidized phospholipids.
  
  
  RESULTS
  It was the aim of this study to determine the role of short-chain oxidized phospholipids as components of modified LDL in cultured macrophages. For this purpose we investigated the effects of the following oxidized phospholipids on cell viability and apoptosis: 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine (PGPC), 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC) and oxidized alkylacyl phospholipids including 1-O-hexadecyl-2-glutaroyl-sn-glycero-3-phosphocholine (E-PGPC) and 1-O-hexadecyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (E-POVPC). We found that these compounds induced apoptosis in RAW264.7 and bone marrow-derived macrophages. The sn-2 carboxyacyl lipid PGPC was more toxic than POVPC which carries a reactive aldehyde function in position sn-2 of glycerol. The alkylacyl phospholipids (E-PGPC and E-POVPC) and the respective diacyl analogs show similar activities. Apoptosis induced by POVPC and its alkylether derivative could be causally linked to the fast activation of an acid sphingomyelinase, generating the apoptotic second messenger ceramide. In contrast, PGPC and its ether analog only negligibly affected this enzyme pointing to an entirely different mechanism of lipid toxicity. The higher toxicity of PGPC is underscored by more efficient membrane blebbing from apoptotic cells. In addition, the protein pattern of PGPC-induced microparticles is different from the vesicles generated by POPVC.
  
  
  CONCLUSIONS
  In summary, our data reveal that oxidized phospholipids induce apoptosis in cultured macrophages. The mechanism of lipid toxicity, however, largely depends on the structural features of the oxidized sn-2 chain.
authors.affiliation: Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, A-8010, Graz, Austria.
authors.forename: Ute
authors.initials: U
authors.lastname: Stemmer
authors.forename: Zsuzsanna A
authors.initials: ZA
authors.lastname: Dunai
authors.forename: Daniel
authors.initials: D
authors.lastname: Koller
authors.forename: Gabriel
authors.initials: G
authors.lastname: Pürstinger
authors.forename: Elfriede
authors.initials: E
authors.lastname: Zenzmaier
authors.forename: Hans P
authors.initials: HP
authors.lastname: Deigner
authors.forename: Elma
authors.initials: E
authors.lastname: Aflaki
authors.forename: Dagmar
authors.initials: D
authors.lastname: Kratky
authors.forename: Albin
authors.initials: A
authors.lastname: Hermetter
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D050197:Atherosclerosis / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D002518:Ceramides / Q000737:chemistry / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000737:chemistry / Q000494:pharmacology; D013108:Sphingomyelin Phosphodiesterase / Q000737:chemistry / Q000378:metabolism
chemical_list: D002518:Ceramides; D008077:Lipoproteins, LDL; D010743:Phospholipids; D013108:Sphingomyelin Phosphodiesterase