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Enzymatic modification of low density lipoprotein by purified lipoxygenase plus phospholipase A2 mimics cell-mediated oxidative modification.
- Source :
-
Journal of lipid research [J Lipid Res] 1988 Jun; Vol. 29 (6), pp. 745-53. - Publication Year :
- 1988
-
Abstract
- Low density lipoprotein (LDL) can be oxidatively modified by cultured endothelial cells or by cupric ions, resulting in increased macrophage uptake of the lipoprotein. This process could be relevant to the formation of macrophage-derived foam cells in the early atherosclerotic lesion. The mechanism of endothelial cell modification of LDL is unknown. In the present work we show that incubation of LDL with purified soybean lipoxygenase, in the presence of pure phospholipase A2, can mimic endothelial cell-induced oxidative modification. Typically, incubation with lipoxygenase plus phospholipase A2 caused: 1) generation of about 15 nmol of thiobarbituric acid-reactive substances per mg of LDL protein; 2) a 4- to 7-fold increase in the rate of subsequent macrophage degradation of the LDL; 3) a 10-fold decrease in recognition by fibroblasts; 4) a marked increase in electrophoretic mobility in agarose gels; and, 5) disappearance of intact apoprotein B on SDS polyacrylamide gels. Degradation of the enzymatically modified LDL by macrophages was competitively inhibited by endothelial cell-modified LDL and by polyinosinic acid, but only partially suppressed by acetylated LDL. The lipoxygenase plus phospholipase A2-induced modification of LDL is not necessarily identical to endothelial cell modification, but it is a useful model for studying the mechanism of oxidative modification of LDL. This work also represents the first example of oxidative modification of LDL by specific enzymes leading to enhanced recognition by macrophages.
- Subjects :
- Animals
Aorta metabolism
Apolipoproteins B metabolism
Cells, Cultured
Copper pharmacology
Endothelium, Vascular metabolism
Fibroblasts metabolism
Lipid Peroxides biosynthesis
Macrophages metabolism
Oxidation-Reduction
Phospholipases A2
Rabbits
Lipoproteins, LDL metabolism
Lipoxygenase pharmacology
Phospholipases pharmacology
Phospholipases A pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0022-2275
- Volume :
- 29
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Journal of lipid research
- Publication Type :
- Academic Journal
- Accession number :
- 3139813