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Abstract: Oxidized phospholipids (oxPL) have been found in atherosclerotic plaques and have been associated with the development of atherosclerosis. To investigate the LDL modifying effects of oxPL and subsequent consequences for macrophages, murine bone marrow macrophages were treated with LDL modified with the oxidation products of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine, oxPAPC. Effects of oxPAPC-modified LDL (oxPAPC-LDL) on macrophages were compared to native LDL, copper oxidized LDL (Cu-oxLDL) and acetylated LDL (acLDL). LDL treatment with oxPAPC or CuSO4 induced active oxidation of the LDL particles, resulting in significant increase in F2-isoprostanes, typical for LDL oxidation, compared with native LDL, acLDL or PAPC-LDL. Uptake of oxPAPC-LDL in macrophages was mediated by CD36 pathways as shown by SR-A and CD36 inhibitors. Surprisingly, both Cu-oxLDL and acLDL induced cholesterol ester accumulation in macrophages while oxPAPC-LDL did not. Microarray analysis showed a pronounced similarity between Cu-oxLDL and oxPAPC-LDL gene expression induction, whereas acLDL and oxPAPC-LDL did not overlap. The main feature shared by oxPAPC-LDL and Cu-oxLDL was the induction of the glutathione dependent antioxidant response, indicating an important role in protecting against both types of modified LDL induced stress. Our experiments show that oxPL modifies LDL, resulting in a minimally oxidized particle that shares many features of classically copper oxidized LDL and that may have relevant in vivo properties. [Copyright &y& Elsevier]

Objectives: We sought to examine the presence of hypoxia in human carotid atherosclerosis and its association with hypoxia-inducible transcription factor (HIF) and intraplaque angiogenesis. Background: Atherosclerotic plaques develop intraplaque angiogenesis, which is a typical feature of hypoxic tissue and expression of HIF. Methods: To examine the presence of hypoxia in atherosclerotic plaques, the hypoxia marker pimonidazole was infused before carotid endarterectomy in 7 symptomatic patients. Also, the messenger ribonucleic acid (mRNA) and protein expression of HIF1α, HIF2α, HIF-responsive genes (vascular endothelial growth factor [VEGF], glucose transporter [GLUT]1, GLUT3, hexokinase [HK]1, and HK2), and microvessel density were determined in a larger series of nondiseased and atherosclerotic carotid arteries with microarray, quantitative reverse transcription polymerase chain reaction, in situ hybridization, and immunohistochemistry. Results: Pimonidazole immunohistochemistry demonstrated the presence of hypoxia, especially within the macrophage-rich center of the lesions. Hypoxia correlated with the presence of a thrombus, angiogenesis, and expression of CD68, HIF, and VEGF. The mRNA and protein expression of HIF, its target genes, and microvessel density increased from early to stable lesions, but no changes were observed between stable and ruptured lesions. Conclusion: This is the first study directly demonstrating hypoxia in advanced human atherosclerosis and its correlation with the presence of macrophages and the expression of HIF and VEGF. Also, the HIF pathway was associated with lesion progression and angiogenesis, suggesting its involvement in the response to hypoxia and the regulation of human intraplaque angiogenesis. [Copyright &y& Elsevier]