Generation and metabolism of oxidized phospholipids which are active components in oxidized low density lipoprotein.

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Oxidized low density lipoprotein (OxLDL) is believed to be a cruicial factor for atherogenesis. Oxidized phosphatidylcholines (OxPC) formed in OxLDL should be key compounds for atherogenesis, since they are involved in recognition by macrophages and are capable of activating endothelial cells and other vascular cells. We investigated, by utilizing an anti-OxPC monoclonal antibody, DLH3, the metabolic fate of OxPC-apoB complex in foam cells and OxPC generation in various types of OxLDL preparations.Foam cells in human atherosclerotic lesions were simultaneously stained immunohistochemically with DLH3 and anti-apoB antibody, indicating accumulation of OxPC-apoB coomplex. Careful measurement of the amounts of OxPC-apoB coomplex present in J774 macrophages revealed that a part of OxLDL taken up by macrophages were accumulated in the cells. Partially degraded OxLDL (less than 100 kDa) were recovered in secondary lysosome fractions when intracellular organelles were fractionated on a sucrose … More density gradient. These observations provide a metabolic rationale why and how OxLDL-related antigens are accumulated in foam cells in atherosclerotic lesions.Recently, minimally modified LDL (MM-LDL), which is prepared by moderate oxidation contitions, is reported to be a good model for physiological OxLDL.We introduced a sensitve methos to measure free OxPCs containing aldehyde group by converting them to fluorescent derivertives after treatment with 1, 4-cyclohexanedione. MM-LDL was prepared by incubating LDL with FeSO4 at 4℃. Although modification status of whole particles for MM-LDL seemed to be very moderate judging by TBARS values and eleclromobility on agarose gel, the amounts of free and complex forms of OxPC generated in MM-LDL were rather higher than copper-treated OxLDL.It is certainly needed to test the biological properties of the MM-LDL preparations as the next step, but this observation might be a interesting clue to elucidate the contribution of OxPC formed in OxLDL for atherogenesis. Less