氧化修饰高密度脂蛋白的致动脉粥样硬化作用

高密度脂蛋白（ｈｉｇｈ ｄｅｎｓｉｔｙ ｌｉｐｏｐｒｏｔｅｉｎ ,ＨＤＬ）具有抗动脉粥样硬化（ａｔｈｅｒｏｓｃｌｅｒｏｓｉｓ,ＡＳ）作用,一旦发生氧化修饰后,即具致ＡＳ作用。氧化修饰ＨＤＬ（ｏｘｉｄｉｚｅｄ ＨＤＬ,ＯＸ－ＨＤＬ）通过减少胆固酥因管平滑肌细胞（ｓｍｏｏｔｈ ｍｕｓｃｌｅ ｃｅｌｌ,ＳＭＣ）,内皮细胞及巨噬细胞流出,抑制胆固醇逆向转运;     

介导巨噬细胞摄取氧化修饰极低密度脂蛋白的受体

用未标记氧化修饰极低密度脂蛋白（ｏｘ－ＶＬＤＬ）、ｎ－ＶＬＤＬ、乙酰ＬＤＬ竞争１２５Ｉ－ｏｘ－ＶＬＤＬ与巨噬细胞的结合。在浓度为２００μｇ蛋白／ｍｌ时,分别抑制标记ｏｘ－ＶＬＤＬ结合量的７０～７８％、６０～７０％和２５～３５％。用未标记ｏｘ－ＶＬＤＬ竟争１２５Ｉ－ｎ－ＶＬＤＬ与巨噬细胞的结合,能抑制７７％。结果说明ｏｘ－ＶＬＤＬ主要通过ｎ－ＶＬＤＬ受体进入巨噬细胞。以ｏｘ－ＶＬＤＬ与ｏｘ－ＬＤＬ进行交叉竞争时,ｏｘ－ＶＬＤＬ与ｏｘ－ＬＤＬ自身可抑制标记ｏｘ－ＶＬＤＬ或ｏｘ－ＬＤＬ的７５～８２％,而ｏｘ－ＶＬＤＬ或ｏｘ－ＬＤＬ的交叉竞争仅３８～４０％。表明ｏｘ－ＶＬＤＬ与ｏｘ－ＬＤＬ有部分共同的构象与巨噬细胞的脂蛋白受体结合,但ｏｘ－ＶＬＤＬ不是经ｏｘ－ＬＤＬ受体被巨噬细胞摄取。     

动脉壁细胞氧化修饰极低密度脂蛋白

将正常极低密度脂蛋白（ｎ－ＶＬＤＬ）分别与动脉壁的三种主要细胞：巨噬细胞（Ｍφ）、内皮细胞（ＥＣ）、平滑肌细胞（ＳＭＣ）温育２４小时后,ＶＬＤＬ的ＴＢＡＴＳ值明显增高,琼脂糖电泳速度加快,溶血卵磷脂与卵磷脂（ＰＣ）的比值明显升高,载脂蛋白的Ｂ１００（ａｐｏＢ１００）发生降解,未见集中的降解区带,ａｐｏ遥相对含量在各组无明显变化,加入抗氧化剂２,６－叔丁基甲苯能抑制上述变化,这些结果表明：动脉壁的三     

氧化修饰低密度脂蛋白与动脉粥样硬化

氧化修饰低密度脂蛋白与动脉粥样硬化周永列（浙江省人民医院,杭州３１００１４）关键词氧化修饰低密度脂蛋白,动脉粥样硬化在动脉粥样硬化（ＡＳ）与血浆脂质关系的研究中,血浆低密度脂蛋白（ＬＤＬ）浓度升高被认为是引起ＡＳ的重要危险因素而受到广泛的重视。但是脂...     

氧化修饰低密度脂蛋白与动脉粥样硬化

动脉粥样硬化的发生发展与低密度脂蛋白受到氧化修饰有关。本文从以下四个方面对本室的工作进行了综述：（１）动脉粥样硬化机体受到脂质过氧化损伤;（２）Ｏｘ－ＬＤＬ对内皮细胞、平滑肌细胞和巨噬细胞的毒性效应;（３）Ｏｘ－ＬＤＬ和ＭＤＡ－ＬＤＬ的比较及与Ｏｘ－ＬＤＬ和ＭＤＡ－ＬＤＬ结合的清道夫受体的特征;（４）不同方法对ＬＤＬ氧化修饰的比较和以ＬＤＬ氧化修饰为模型对某些物质的抗氧化修饰研究。研究结果为动脉粥     

介导巨噬细胞摄取氧化修饰极低密试脂蛋白的受体

用未标记氧化修饰极低密度脂蛋白（ｏｘ－ＶＬＤＬ）、ｎ－ＶＬＤＬ、乙酰ＬＤＬ竞争＾１２５Ｉ－ｏｘ－ＶＬＤＬ与巨噬细胞的结合。在浓度为２００μｇ蛋白／ｍｌ时,分别抑制标记ｏｘ－ＶＬＤＬ结合量的７０￣７８％、６０￣７０％和２５￣３５％。用未标记ｏｘ－ＶＬＤＬ竞争＾１２５Ｉ－ｎ－ＶＬＤＬ与巨噬细胞的结合,能抑制７７％。结果说明ｏｘ－ＶＬＤＬ主要通过ｎ－ＶＬＤＬ受体进入巨噬细胞。以ｏｘ－ＶＬＤＬ与ｏｘ－ＬＤ     

脂质过氧化作用与动脉粥样硬化

本文根据新近文献和作者工作,从动脉粥样硬化患者和实验性动脉粥样硬化动物的抗氧化能力变化以及与动脉粥样硬化发生有关的某些环节的脂质过氧化损伤因素,说明动脉粥样硬化的发生发展与脂质过氧化损伤有关。     

巨噬细胞极低密度脂蛋白受体的调节作用

本文研究了小鼠腹腔巨噬细胞极低密度脂蛋白(VLDL)受体的调节。用富含甘油三酯(TG)的VLDL与小鼠巨噬细胞预温育后,细胞结合~(125)I-VLDL的最大结合容量(Bmax)比对照细胞只降低5％(1071/1127ng/mg细胞蛋白质),当细胞内TG增加到对照的2.5倍时,细胞摄取及降解~(125)I-VLDL的量分别下降40％和22％;乙酰-低密度脂蛋白(AC-LDL)预温育的细胞结合~(125)I-VLDL的Bmax比对照细胞只降低14％(633/831ng/mg细胞蛋白质),当细胞内胆固醇(Ch)增加到对照的23倍时,细胞摄取及降解~(125)I-VLDL的量只分别下降10％和21％。此后随着细胞内TG或Ch含量的增加,摄取及降解~(125)I-VLDL的量仍保持不变。 结论:细胞内TG或Ch含量对VLDL受体的调节作用微弱,与TG相比,Ch的调节作用更弱。     

氧化磷脂与动脉粥样硬化

磷脂是构成生物膜和脂蛋白的重要成分,容易在自由基或非自由基以及酶促条件下发生氧化修饰,形成氧化磷脂(oxidized phospholipids,OxPLs),并进一步产生具有不同生物活性的氧化产物.临床证据表明,OxPLs在动脉粥样硬化(ath-erosclerosis,AS)发展过程中不断生成和转化,并在病变处积累...     

氧化低密度脂蛋白对THP-1巨噬细胞吞噬和分泌功能的影响

目的:探讨氧化低密度脂蛋白(oxidized low density lipoprotein,ox-LDL)对巨噬细胞源性泡沫细胞吞噬功能和炎症相关因子分泌功能的影响。方法:利用佛波酯(phorbol ester,PMA)诱导THP-1细胞分化形成巨噬细胞,之后采用ox-LDL处理48小时后,诱导其形成泡沫细胞。利用中性红吞噬实验,分析泡沫细胞形成前后吞噬功能的变化;通过ELISA法,检测细胞培养上清中肿瘤坏死因子α(tumor necrosis factorα,TNF-α)含量,观察ox-LDL对THP-1巨噬细胞功能的影响。结果:细胞形态学结果表明,我们成功利用ox-LDL诱导THP-1巨噬细胞形成泡沫细胞;进一步发现ox-LDL诱导THP-1巨噬细胞表面的清道夫受体CD36表达升高,并促进细胞吞噬功能增加,进一步促进细胞内胆固醇含量显著升高(P0.05);同时,ox-LDL能够刺激巨噬细胞大量分泌TNF-α(P0.05)。结论:ox-LDL通过增强清道夫受体CD36表达,提高巨噬细胞的吞噬功能,引起大量胆固醇聚集,产生细胞毒性损伤,并促进TNF-α炎性因子的大量分泌。     

维生素C抑制低密度脂蛋白的氧化修饰

研究了不同浓度维生素 C 对 Cu²⁺诱导的低密度脂蛋白(LDL)氧化修饰的抑制作用,通过测定硫代巴比妥酸反应物质(TBARS),荧光物质(lipofusion)扫描及琼脂糖电泳,显示一定浓度的维生素 C 在24h 内对 LDL 的氧化修饰具有抑制作用,并呈现量效效应.提示维生素 C 作为体内存在的一种抗氧化物,可抑制 LDL的氧化修饰,从而在防治动脉粥样硬化的发生具有一定意义.     

CideB Protein Is Required for the Biogenesis of Very Low Density Lipoprotein (VLDL) Transport Vesicle

Nascent very low density lipoprotein (VLDL) exits the endoplasmic reticulum (ER) in a specialized ER-derived vesicle, the VLDL transport vesicle (VTV). Similar to protein transport vesicles (PTVs), VTVs require coat complex II (COPII) proteins for their biogenesis from the ER membranes. Because the size of the VTV is large, we hypothesized that protein(s) in addition to COPII components might be required for VTV biogenesis. Our proteomic analysis, supported by Western blotting data, shows that a 26-kDa protein, CideB, is present in the VTV but not in other ER-derived vesicles such as PTV and pre-chylomicron transport vesicle. Western blotting and immunoelectron microscopy analyses suggest that CideB is concentrated in the VTV. Our co-immunoprecipitation data revealed that CideB specifically interacts with VLDL structural protein, apolipoprotein B100 (apoB100), but not with albumin, a PTV cargo protein. Confocal microscopic data indicate that CideB co-localizes with apoB100 in the ER. Additionally, CideB interacts with COPII components, Sar1 and Sec24. To investigate the role of CideB in VTV biogenesis, we performed an in vitro ER budding assay. We show that the blocking of CideB inhibits VTV budding, indicating a direct requirement of CideB in VTV formation. To confirm our findings, we knocked down CideB in primary hepatocytes and isolated ER and cytosol to examine whether they support VTV budding. Our data suggest that CideB knockdown significantly reduces VTV biogenesis. These findings suggest that CideB forms an intricate COPII coat and regulates the VTV biogenesis.     

Glucose-Modified Low Density Lipoprotein Enhances Human Monocyte Chemotaxis

In diabetes mellitus the progression of atherosclerosis is accelerated. The interaction of glucose with athero-genic lipoproteins may be relevant to the mechanisms responsible for this vascular damage. The aim of this study was to examine the effect of glucose-modified low density lipoprotein (LDL) on human monocyte chemotaxis and to investigate the roles of oxidation and glycation in the generation of chemotactic LDL. Cu(II)-mediated LDL oxidation was potentiated by glucose in a dose-dependent manner and increased its chemotactic activity. Incubation with glucose alone, under conditions where very little oxidation was observed, also increased the chemotactic property of LDL. Neither diethylenetriamine pentaacetic acid (DETAPAC) nor aminoguanidine, which both inhibited LDL oxidation, completely inhibited the chemotactic activity of glycated oxidised LDL. The results suggest that both oxidation and glycation contribute to increased chemotactic activity.     

极低密度脂蛋白受体研究进展

极低密度脂蛋白受体 (VLDL R)属于低密度脂蛋白受体 (LDL R)超家族 ,结构上与LDL R极为相似 ,而在结合特性、组织分布及生理功能上存在较大的差异 .近年来的研究表明 ,VLDL R配体结合域中的重复序列参与配体的结合 ,并已初步确定受体N端的 4个重复序列中含有与配体结合的重要位点 ;在哺乳动物体内 ,VLDL R主要分布于脂代谢活跃的组织细胞 ,如 :心肌、骨骼肌和脂肪组织等 ,表明其与脂质尤其是甘油三酯的代谢密切相关 ;动脉粥样硬化 (AS)的病变斑块组织中该受体的表达量很高 ,推测VLDL R参与了AS的病变过程 ;在不同的细胞内 ,VLDL R及其亚型的表达并不一致 ,并发现与各种生理、病理变化相关 ,已经发现多种转录因子参与VLDL R表达的调控 ;基因敲除研究也不断揭示VLDL R新的功能意义 ,特别是发现了VLDL R在脑的发育过程中的重要信号作用 ,这些研究已使人们对VLDL R有了新的更全面的认识     

极低密度脂蛋白对巨噬细胞载脂蛋白E基因表达的调节

巨噬细胞（M）是动脉粥样硬化（AS）斑块中泡沫细胞的主要来源之一,它可通过其表面的多种脂蛋白受体介导摄取合APOB或APOE的脂蛋白,导致M的脂质增加．此外,M有较强的分泌ApOE的能力[1],这一现象虽已发现多年,但意义尚不清楚VLDL是一种含APOE的脂蛋白,它能通过M膜上识别APOE的受体进入M,从而促进Mg内脂质堆积,并与AS密切相关[2,3]．流行病学调查发现在我国的高脂血症中2／3为VLDL升高为主的高甘油三酯（HTG）血症．另外,Evans等报道HTG血症患者的血浆中以ApoE－poorVLDL升高为主,它们在血浆中清除的速率较Apo…     

Fenofibrate Increases Very Low Density Lipoprotein Triglyceride Production Despite Reducing Plasma Triglyceride Levels in APOE*3-Leiden.CETP Mice

The peroxisome proliferator-activated receptor alpha (PPARα) activator fenofibrate efficiently decreases plasma triglycerides (TG), which is generally attributed to enhanced very low density lipoprotein (VLDL)-TG clearance and decreased VLDL-TG production. However, because data on the effect of fenofibrate on VLDL production are controversial, we aimed to investigate in (more) detail the mechanism underlying the TG-lowering effect by studying VLDL-TG production and clearance using APOE*3-Leiden.CETP mice, a unique mouse model for human-like lipoprotein metabolism. Male mice were fed a Western-type diet for 4 weeks, followed by the same diet without or with fenofibrate (30 mg/kg bodyweight/day) for 4 weeks. Fenofibrate strongly lowered plasma cholesterol (−38%) and TG (−60%) caused by reduction of VLDL. Fenofibrate markedly accelerated VLDL-TG clearance, as judged from a reduced plasma half-life of glycerol tri[³H]oleate-labeled VLDL-like emulsion particles (−68%). This was associated with an increased post-heparin lipoprotein lipase (LPL) activity (+110%) and an increased uptake of VLDL-derived fatty acids by skeletal muscle, white adipose tissue, and liver. Concomitantly, fenofibrate markedly increased the VLDL-TG production rate (+73%) but not the VLDL-apolipoprotein B (apoB) production rate. Kinetic studies using [³H]palmitic acid showed that fenofibrate increased VLDL-TG production by equally increasing incorporation of re-esterified plasma fatty acids and liver TG into VLDL, which was supported by hepatic gene expression profiling data. We conclude that fenofibrate decreases plasma TG by enhancing LPL-mediated VLDL-TG clearance, which results in a compensatory increase in VLDL-TG production by the liver.     

低密度脂蛋白胆固醇升高在家兔动脉粥样硬化发生发展中的意义

目的观察低密度脂蛋白胆固醇(LDL-c)对家兔动脉粥样硬化(AS)形成的影响,探讨AS的发生机制。方法以高脂饲料复制家兔实验性AS模型,分阶段检测家兔血清胆固醇(TC)、甘油三脂(TG)、高密度脂蛋白胆固醇(HDL-c)和低密度脂蛋白胆固醇(LDL-c)含量;观察主动脉内膜病理学变化;分析主动脉内膜增生程度及AS斑块面积与血浆脂蛋白水平的相关性。结果高脂组家兔主动脉粥样硬化面积和内膜增生程度明显较对照组增加(P<0.01),血浆LDL-c水平明显较对照组升高(P<0.01);动脉内膜增生程度及AS斑块面积均与血浆LDL-c水平呈非常显著正相关(r=0.837,P<0.001)。结论提示血浆LDL-c水平升高,是致AS发生发展的重要原因。