中文摘要：

目的：以THP-1巨噬细胞源性泡沫细胞为研究对象，观察载脂蛋白A—I对THP-1巨噬细胞源性泡沫细胞胆固醇流出和三磷酸腺苷结合盒转运体A1（ABCA1）的影响，从而探讨载脂蛋白A—I对动脉粥样硬化（As）发生发展的影响。方法：用液体闪烁计数器检测细胞内胆固醇流出，高效液相色谱分析细胞内总胆固醇、游离胆固醇和胆固醇酯含量，运用逆转录-多聚酶链反应和Western印迹分别检测ABCA1 mRNA与ABCA1蛋白的表达，用流式细胞术检测细胞平均ABCA1荧光强度。结果：载脂蛋白A—I引起THP-1巨噬细胞源性泡沫细胞总胆固醇、游离胆固醇与胆固醇酯呈时间依赖性减少，而ABCA1蛋白质水平、细胞平均ABCA1荧光强度以及细胞内胆固醇流出呈时间依赖性增加，但ABCA1 mRNA没有明显变化。巯基蛋白酶抑制剂（1eupeptin和ALLN）增加ABCA1蛋白质水平，而其它蛋白酶抑制剂（pepstatin A、aprotinin及phosphommiddon）不增加ABCA1蛋白质水平，蛋白体抑制剂（1actacytin）和溶酶体抑制剂（NH4Cl）也不影响ABCA1蛋白质水平。结论：巯基蛋白酶可降解THP-1巨噬细胞源性泡沫细胞ABCA1蛋白质，而载脂蛋白A—I可阻碍巯基蛋白酶降解ABCA1蛋白质，从而提高THP-1巨噬细胞源性泡沫细胞ABCA1蛋白质水平，增加细胞内胆固醇流出，降低细胞内胆固醇聚积。

英文摘要：

AIM： To study the effects of apolipoprotein （apo） A - I on ATP binding cassette transporter A1 （ABCA1） degradation and cholesterol efllux in THP- 1 macrophage -derived foam oells. METHODS： After exposure of the cultured THP - 1 macrophage - derived foam cells to apolipoprotein A - I for different time, cholesterol efflux, ABCA1 mRNA and protein level were determined by liquid scintillation counting, reverse transcriptase - polymerase chain reaction and Western blotting, respectively. The mean ABCA1 fluorescence intensity on THP - 1 macrophage - derived foam cells was detected by flow cytometry. RESULTS： ApoA - I markedly increased ABCA1 - mediated cholesterol efflux from THP - 1 macrophage - derived foam cells. This was accompanied by an increase in the content of ABCA1. ApoA - I did not alter ABCA1 mRNA abundance. Thiol protease inhibitora increased the level of ABCA1 protein and slowed its decay in THP - 1 macrophage - derived foam cells, whereas none of the proteosome - specific inhibitor lactacystln, other protease inhibitors, or the lysosomal inhibitor NH4Cl showed such effects. The apoA - I mediated cellular cholesterol efflux was enhanced by thiol protease inhibitors. CONCLUSION： Thiol protease inhibitors might provide an alternative way to upregulate ABCA1 protein. This strategy is especially appealing since it may mimic the stabilizing effect of the natural ligands apoA - I .