APOLIPOPROTEIN A-I-MEDIATED EFFLUX OF STEROLS FROM OXIDIZED LDL-LOADED MACROPHAGES
APOLIPOPROTEIN A-I-MEDIATED EFFLUX OF STEROLS FROM OXIDIZED LDL-LOADED MACROPHAGES
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DOI：
10.1161/01.atv.15.2.276
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发表时间：
1995-02-01
影响因子：
8.7
通讯作者：
DEAN, RT
中科院分区：
文献类型：
--
作者：
KRITHARIDES, L;JESSUP, W;DEAN, RT
尽管氧化低密度脂蛋白（OxLDL）可以在体外积聚在巨噬细胞中，产生负载胆固醇的细胞，但很少有人关注负载有OxLDL的巨噬细胞输出胆固醇和氧化甾醇部分的能力。通过将小鼠腹膜巨噬细胞的原代培养物与乙酰化 LDL (AcLDL) 或 OxLDL 一起孵育 24 小时，产生体外脂质负载细胞。通过高效液相色谱法测定天然胆固醇、单独胆固醇酯和7-酮胆固醇的细胞含量。然后将这些细胞与含有载脂蛋白（ape）A-I和白蛋白或单独白蛋白的培养基一起孵育长达24小时；胆固醇和氧化甾醇的流出量是根据细胞内消耗和细胞外积累来测量的。负载 AcLDL 的巨噬细胞积累胆固醇和大量胆固醇酯，而负载 OxLDL 的细胞则积累胆固醇、多种氧化化合物（主要是 7-酮胆固醇）和相对少量的胆固醇酯。 AcLDL 衍生细胞在 24 小时内以未酯化胆固醇的形式将约 50% 的总胆固醇（未酯化和酯化）释放到含有 apo A-I 的培养基中，而 OxLDL 衍生细胞在同一时期释放约 30% 的总胆固醇和 7% 的 7-酮胆固醇总含量。在没有 apo A-I 的情况下，任何甾醇的流出量都很小。尽管使用 Sandoz 58-035 抑制细胞酰基辅酶 A：胆固醇酰基转移酶，AcLDL 或 OxLDL 负载细胞释放的胆固醇和 7-酮胆固醇的比例并未降低，尽管这些细胞中游离胆固醇和（OxLDL 负载细胞中）游离 7-酮胆固醇的比例发生了显着变化。此外，单个亚细胞细胞器部分中胆固醇和7-酮胆固醇的亚细胞分布与未负载细胞中游离胆固醇的分布相同，表明负载OxLDL的细胞中的这些甾醇没有选择性地隔离在溶酶体中。负载 OxLDL 的细胞释放 7-酮胆固醇的效率远低于胆固醇。此外，负载 OxLDL 的细胞释放胆固醇的效率低于 AcLDL 衍生的细胞。这种 OxLDL 负载细胞流出的损害可能会影响体内泡沫细胞表型的产生和持续，因此可能导致 OxLDL 的致动脉粥样硬化性。
Although oxidized low-density lipoprotein (OxLDL) can accumulate in macrophages in vitro, generating cholesterol-loaded cells, little attention has been paid to the capacity of such macrophages loaded with OxLDL to export cholesterol and oxidized sterol moieties. In vitro lipid-loaded cells were generated by incubating primary cultures of mouse peritoneal macrophages with acetylated LDL (AcLDL) or OxLDL for 24 hours. The cellular content of native cholesterol, individual cholesteryl esters, and 7-ketocholesterol was determined by high-performance liquid chromatography. These cells were then incubated with medium containing apolipoprotein (ape) A-I and albumin or albumin alone for up to 24 hours; cholesterol and oxidized sterol efflux were measured both in terms of intracellular depletion and extracellular accumulation. Macrophages loaded with AcLDL accumulated cholesterol and large quantities of cholesteryl esters, whereas OxLDL-loaded cells accumulated cholesterol, a number of oxidized compounds (predominantly 7-ketocholesterol), and a relatively small quantity of cholesteryl esters. AcLDL-derived cells released approximately 50% of their total cholesterol (unesterified and esterified) to apo A-I-containing medium over 24 hours in the form of unesterified cholesterol, whereas OxLDL-derived cells released approximately 30% of their total cholesterol and 7% of their total content of 7-ketocholesterol over the same period. There was minimal efflux of any sterol in the absence of apo A-I. The proportions of cholesterol and 7-ketocholesterol released by either AcLDL- or OxLDL-loaded cells were not reduced by inhibiting cellular acyl-CoA:cholesterol acyl transferase using Sandoz 58-035, despite substantial alterations in the proportions of both free cholesterol and (in OxLDL-loaded cells) free 7-ketocholesterol in these cells. Furthermore, the subcellular distributions of both cholesterol and 7-ketocholesterol in individual subcellular organelle fractions were identical to that of free cholesterol in nonloaded cells, indicating that these sterols in OxLDL-loaded cells are not selectively sequestered in lysosomes. 7-Ketocholesterol is released much less efficiently than cholesterol from OxLDL-loaded cells. In addition, OxLDL-loaded cells release cholesterol less efficiently than do cells derived from AcLDL. It is possible that this impairment of efflux from OxLDL-loaded cells influences the generation and persistence of the foam cell phenotype in vivo and may therefore contribute to the atherogenicity of OxLDL.