title: Oxidized but not native cardiolipin has pro-inflammatory effects, which are inhibited by Annexin A5.
abstract: OBJECTIVE
  Cardiolipin (CL) is a phospholipid with an unusual dimeric structure containing four double-bonds and is easily oxidized. CL is present in mitochondria. Here we explored potential pro-inflammatory properties implicated in cardiovascular disease (CVD): activation of endothelial cells, 5-lipoxygenase (5-LOX) and leukotriene B4 (LTB4), by oxidized CL (oxCL) and inhibitory effects of Annexin A5, an antithrombotic and antiinflammatory plasma protein.
  
  
  METHODS
  In monocytes/macrophages and neutrophils, calcium mobilization was monitored spectrophotometrically with Fura-2 and synthesis of LTB4 was analyzed by EIA. Expression of adhesion molecules on endothelial cells was studied by FACScan. Binding of Annexin A5 were analyzed by ELISA. The mRNA expression of 5-LOX and cyclooxygenase-2 was assessed by Real-Time PCR.
  
  
  RESULTS
  We demonstrate that oxCL but not its non-oxidized counterpart CL induces biosynthesis of LTB4 and increases intracellular concentrations of calcium in monocytes/macrophages and neutrophils. oxCL rather than CL selectively elevates gene expression of 5-LOX but not COX-2 in human macrophages. Furthermore, oxCL but not CL raises levels of adhesion molecules ICAM-1 and VCAM-1 in endothelial cells. Annexin A5 can bind oxCL to abolish all these oxCL-induced effects.
  
  
  CONCLUSIONS
  oxCL may promote inflammation and related diseases especially in conditions involving unresolved apoptosis and necrosis, such as atherosclerosis, where free oxCL is likely to be released from liberated mitochondria. Increased intracellular calcium could activate 5-LOX to produce Leukotriene B4 (LTB4). Annexin A5 inhibits the pro-inflammatory effects of oxCL and its potential therapeutic use when oxCL is implicated in inflammation could be of interest.
authors: Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
authors: Min
authors: M
authors: Wan
authors: IMM, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden; Divisions of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Insitutet, Stockholm, Sweden. Electronic address: xiang.hua@ki.se.
authors: Xiang
authors: X
authors: Hua
authors: IMM, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.
authors: Jun
authors: J
authors: Su
authors: IMM, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.
authors: Divya
authors: D
authors: Thiagarajan
authors: IMM, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.
authors: Anna G
authors: AG
authors: Frostegård
authors: Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
authors: Jesper Z
authors: JZ
authors: Haeggström
authors: IMM, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden; Divisions of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Insitutet, Stockholm, Sweden; Acute Internal Medicine, Karolinska University Hospital, Huddinge, Sweden.
authors: Johan
authors: J
authors: Frostegård
mesh_terms: D017304:Annexin A5 / Q000378:metabolism / Q000494:pharmacology*; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002308:Cardiolipins / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced; D018836:Inflammation Mediators / Q000494:pharmacology; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D007975:Leukotriene B4 / Q000096:biosynthesis; D008264:Macrophages / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism; D010084:Oxidation-Reduction; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis
chemical_list: D017304:Annexin A5; D002308:Cardiolipins; D018836:Inflammation Mediators; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D007975:Leukotriene B4; D001094:Arachidonate 5-Lipoxygenase; D002118:Calcium
keywords: Atherosclerosis; Cardiolipin; Inflammation; Leukotrienes; Oxidation