Kawabe Y, Cynshi O, Takashima Y, Suzuki T, Ohba Y, Kodama T
Fujigotemba Research Laboratories Chugai Pharmaceutical Co., Ltd., Shizuoka, Japan.
Arch Biochem Biophys. 1994 May 1;310(2):489-96. doi: 10.1006/abbi.1994.1197.
Oxidation of low-density lipoprotein (LDL) has been considered as an important step in the early pathogenesis of atherosclerosis. We investigated the oxidative modification of LDL by a water-soluble azo-initiator AAPH (2,2,-azo-bis(2-amidinopropane).2HCl) and analyzed the uptake of AAPH-oxidized LDL with mouse peritoneal macrophages. Oxidative modification of LDL by AAPH was similar to the modification induced by copper in regard to the degree of oxidation and formation of aggregated LDL. The aggregated oxidized (AO-) LDL was fractionated by gel permeation chromatography and compared with the monomeric oxidized (MO-) LDL to make clear their characterization. The results of binding, cell association, and degradation with macrophages indicated that both AO- and MO-LDL were bound and endocytosed by macrophages. The cross competition experiment showed that nonreciprocal competition existed among MO-LDL, AO-LDL, and monomeric acetylated (MAc-) LDL. By the sterol accumulation experiment in macrophages with the various types of modified LDL, the cellular sterol accumulation was shown as the following order, AO-LDL > MAc-LDL > MO-LDL. These results indicated that the oxidation by AAPH can induce the aggregation of LDL and that the AO-LDL contribute to lipid accumulation into macrophages more than the MO-LDL.
低密度脂蛋白（LDL）的氧化被认为是动脉粥样硬化早期发病机制中的一个重要步骤。我们研究了水溶性偶氮引发剂AAPH（2,2-偶氮双（2-脒基丙烷）.2HCl）对LDL的氧化修饰，并分析了AAPH氧化型LDL被小鼠腹腔巨噬细胞摄取的情况。就氧化程度和聚集LDL的形成而言，AAPH对LDL的氧化修饰与铜诱导的修饰相似。通过凝胶渗透色谱法对聚集氧化（AO-）LDL进行分级分离，并与单体氧化（MO-）LDL进行比较，以明确它们的特性。巨噬细胞的结合、细胞关联和降解结果表明，AO-LDL和MO-LDL均被巨噬细胞结合并内吞。交叉竞争实验表明，MO-LDL、AO-LDL和单体乙酰化（MAc-）LDL之间存在非相互竞争。通过用各种类型的修饰LDL在巨噬细胞中进行固醇积累实验，细胞固醇积累显示出以下顺序：AO-LDL＞MAc-LDL＞MO-LDL。这些结果表明，AAPH氧化可诱导LDL聚集，且AO-LDL比MO-LDL更有助于脂质在巨噬细胞中的积累。
