Aim To investigate if LPS increases the sterol regulatory element binding proteins ( SREBPs ) cleavage-activating protein ( SCAP )-SREBP2 expres-sion by activation of mTOR signal pathway in THP-1 macrophages , upgrading LDLr level , causing foam-cell formation .Methods THP-1 macrophages were incu-bated in serum free medium in the absence of 5 mg・L-1 LDL alone , or 5 mg・ L-1 LDL plus 200 μg・ L-1 LPS, or 5 mg・ L-1 LDL plus 200 μg・ L-1 LPS plus 10 μg・ L-1 rapamycin .Morphological examination of macrophages was performed with Oil Red O staining . Expression changes of LDLr , SREBP2, SCAP, S6K1 and mTOR mRNA were detected by real time quantita-tive polymerase chain reaction ( PCR ) .Western blot was used to analyze protein expression changes of LD-Lr, S6K1 and mTOR.Translocation of SCAP-SREBP2 complex from the endoplasmic reticulum ( ER ) to the Golgi was determined by confocal microscopy .Results LPS enhanced transformation of THP-1 macrophages into foam cells by increased uptake of lipid as evi-denced by Oil Red O assay .LPS increased mRNA lev-els of LDLr, SREBP2, SCAP, S6K1 and mTOR ( P <0.05) .Rapamycin reduced the mRNA levels of LDLr , SREBP2,SCAP,S6K1 and mTOR induced by LPS ( P<0.05 ) .Western blot demonstrated that LPS also caused over-expression of protein of LDLr , S6K1 and mTOR(P<0.05).Rapamycin reduced the expression of protein of LDLr, S6K1 and mTOR induced by LPS ( P <0.05 ) .Confocal microscopy demonstrated LPS caused an escape of SCAP-SREBP2 complex from the ER to the Golgi .Rapamycin inhibited the translocation of SCAP-SREBP2 complex from the ER to the Golgi . Conclusions Inflammatory stress increases SCAP/SREBP2 expression by activation of mTOR signal path-way, resulting in an escape of SCAP-SREBP2 complex from the ER to the Golgi , furthermore elevating LDLr expression and causing foam-cell formation .Rapamy-cin reverses the activation of mTOR signal pathway and decreases lipid deposition in THP-1 macrophages in-duced by LPS .%目的：研究脂多糖（ LPS）诱导的炎症应激是否通过激活 mTOR 通路，增加 SCAP／SREBP2表达，干扰 SCAP／SREBP2负反馈调控，增加THP－1巨噬细胞对非修饰低密度脂蛋白胆固醇（ LDL）摄取，导致泡沫细胞形成。方法诱导分化成功的THP－1源性巨噬细胞在无血清培养基中培养4 h后，分为对照组（5 mg・ L－1 LDL）、炎症刺激组（5 mg・ L－1 LDL＋200μg・ L－1 LPS）、炎症＋雷帕霉素组（5 mg・ L－1 LDL＋200μg・ L－1 LPS＋10μg・ L－1 Rapamycin ）。以上各组细胞培养24 h后收获。油红O染色法检测各组细胞内脂质沉积情况， Real－time PCR 法检测 LDLr、SREBP2、SCAP、S6K1和 mTOR mRNA 水平， Western blot 法检测 LDLr、S6K1、mTOR蛋白表达，激光共聚焦法检测SCAP 在内质网与高尔基体间的转位情况。结果油红O染色发现，炎症应激增加THP－1巨噬细胞内脂质沉积，雷帕霉素抑制炎症应激诱导的脂质聚积。 Real－time PCR 检测显示，炎症应激上调THP－1巨噬细胞 LDLr、SREBP2、SCAP、S6K1和 mTOR mRNA水平（ P＜0．05），雷帕霉素减少炎症应激诱导的LD－Lr、SREBP2、SCAP、S6 K1和 mTOR mRNA 水平升高（ P ＜0．05）。 Western blot检测发现，炎症应激上调LDLr、S6K1和mTOR蛋白表达（ P＜0．05），雷帕霉素减少炎症应激诱导的LDLr、S6K1和mTOR蛋白表达水平升高（ P＜0．05）。激光共聚焦检测发现，炎症应激增加SCAP／SREBP2从内质网转位到高尔基体，雷帕霉素则抑制炎症应激诱导的 SCAP／SREBP2复合物从内质网转位到高尔基体。结论炎症应激通过激活mTOR通路，上调SCAP／SREBP2表达，致SCAP／SREBP2复合体转位至高尔基体异常增加，LDLr表达上调，致使胆固醇聚积于细胞内，泡沫细胞形成。雷帕霉素能够逆转炎症应激诱导mTOR通路激活，减少细胞内胆固醇沉积，提示炎症应激状态下，mTOR可能是泡沫细胞形成的关键通路。
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