普罗布考抑制氧化低密度脂蛋白上调巨噬细胞清道夫受体CD36的表达

背景 普罗布考是一降脂药,同时具有抗氧化特性,近年来的研究表明其可以通过多种机制抑制动脉粥样硬化的形成,降低经皮冠状动脉成形术后再狭窄的发生.目的 探讨普罗布考对氧化低密度脂蛋白(Ox-LDL)刺激巨噬细胞后清道夫受体CD36表达的抑制效应.方法 用不同浓度的Ox-LDL刺激人单核细胞系THP-1源性巨噬细胞及用不同浓度普罗布考和核因子κBp65(NF-κBp65)特异性抑制剂(PDTC)预处理细胞后再用氧化低密度脂蛋白刺激,半定量RT-PCR方法检测CD36和NF-κBp65的mRNA的表达,Western-blot检测CD36和细胞核NF-κBp65蛋白表达水平.结果 THP-1单核细胞分化成巨噬细胞后,CD36和NF-κBp65 mRNA和蛋白的表达上调;不同浓度的Ox-LDL刺激后,CD36 mRNA和蛋白的表达呈浓度依赖性增加,同时伴NF-κBp65 mRNA和蛋白的表达增加;PDTC和普罗布考干预后,NF-κBp65和CD36的mRNA和蛋白表达下调.结论 Ox-LDL可以通过NF-κBp65途径上调巨噬细胞CD36的表达;而普罗布考则可以抑制CD36的表达,这种作用与抑制NF-κBp65有关.     

CD14对生殖支原体LAMPs激活NF-κB的影响

目的 探讨CD14在生殖支原体(Mg)脂质相关膜蛋白(LAMPs)激活NF-κB中作用。方法 THP-1细胞分别加入人血清和CD14抗体孵育,提取对数期Mg的LAMPs刺激,ELISA法检测其NF-κBp65水平;采用共转染技术和sCD14预孵育LAMPs,刺激Hela细胞,双荧光素酶报告基因分析CD14在LAMPs激活NF-κB中的作用。结果 人血清上调LAMPs诱导THP-1细胞激活NF-κBp65;CD14中和抗体抑制LAMPs诱导THP-1细胞激活NF-κBp65;mCD14和sCD14上调LAMPs诱导Hela细胞激活NF-κB。结论 CD14上调生殖支原体LAMPs激活NF-κB。     

三苯氧胺抑制促动脉粥样硬化基因CD36在单核-巨噬细胞的表达

目的 观察抗肿瘤药物三苯氧胺(tamoxifen,Tam)对促动脉粥样硬化基因CD36在单核-巨噬细胞表达的影响。方法 分别以不同浓度Tam(1,5,10 μmol/L)和它的活性代谢物羟-三苯氧胺(OH-Tam)作用于培养的THP-1单核细胞,24 h后观察CD36蛋白在细胞表面的表达;以氧化型低密度脂蛋白(100mg/L)刺激THP-1单核-巨噬细胞CD36表达,并给予Tam或OH-Tam处理,流式细胞术观察CD36的变化。结果 Tam和OH-Tam可降低单核细胞CD36蛋白表达;同时对氧化型低密度脂蛋白引起的单核-巨噬细胞CD36表达上调具有抑制作用。结论 Tam可能通过抑制CD36在单核-巨噬细胞的表面表达来发挥其抗动脉粥样硬化作用。     

PCKS9通过TLR4/NF-κB/COX-2途径调节单核-内皮细胞黏附性

目的探讨前蛋白转化酶枯草溶菌素9(PCSK9)是否通过人脐静脉内皮细胞(HUVECs)Toll样受体4(TLR4)/核因子κB(NF-κB)/环氧合酶2(COX-2)途径调节单核-内皮细胞黏附性。方法氧化型低密度脂蛋白(ox-LDL)处理HUVECs,real-time PCR与Western blot法检测PCSK9、TLR4、NF-κB p65、COX-2 mRNA和蛋白表达;ox-LDL处理后,用人重组PCSK9蛋白孵育或PCSK9 siRNA转染HUVECs,检测TLR4、NF-κB p65、COX-2 mRNA和蛋白表达;ox-LDL处理后,用人重组PCSK9蛋白与TLR4抑制剂瑞沙托维(TAK-242)或NF-κB抑制剂吡咯烷二硫代氨基甲酸(PDTC)共同孵育HUVECs,检测NF-κB p65与COX-2的mRNA和蛋白表达;COX-2抑制剂(NS398)与人重组PCSK9蛋白先后处理HUVECs后,加入THP-1单核细胞检测单核-内皮细胞黏附性。结果 ox-LDL上调HUVECs的PCSK9、TLR4、NF-κB p65、COX-2 mRNA和蛋白表达(P均0.05);人重组PCSK9蛋白在ox-LDL基础上上调TLR4、NF-κB p65、COX-2 mRNA和蛋白表达(P均0.05);PCSK9 siRNA转染可抑制ox-LDL对TLR4、NF-κB p65、COX-2 mRNA和蛋白表达的上调作用(P均0.05);TAK-242抑制人重组PCSK9蛋白对TLR4、NF-κB p65 mRNA和蛋白表达的上调作用(P均0.05);PDTC抑制人重组PCSK9蛋白对NF-κB p65、COX-2 mRNA和蛋白表达的上调作用(P均0.05);NS398可抑制人重组PCSK9蛋白的促单核-内皮细胞黏附作用(P均0.05)。结论 PCSK9可通过TLR4/NF-κB/COX-2途径调节单核-内皮细胞黏附性。     

普罗布考抑制氧化低密度脂蛋白诱导人脐静脉内皮细胞Fractalkine的表达

目的:探讨氧化低密度脂蛋白(ox-LDL)诱导人脐静脉内皮细胞(HUVEC)产生趋化因子Fractalkine及普罗布考的抑制作用.方法:用不同浓度的ox-LDL刺激HUVEC及用不同浓度普罗布考和PDTC预处理细胞后再用ox-LDL刺激,半定量RT-PCR方法检测Fractalkine和NF-κB p65的mRNA的表达.结果:未用ox-LDL刺激的HUVEC不表达Fractalkine,分别用25、50、100 mg/L浓度的ox-LDL刺激后,Fractalkine mRNA的表达呈浓度依赖性增加,与空白对照组比较分别增加384.58%(P＜0.01)、484.09%(P＜0.01)、558.26%(P＜0.01),同时NF-κB p65 mRNA的表达分别增加15.71%(P＞0.05),41.73%(P＜0.01),66.72%(P＜0.01).40 μmol/L PDTC预处理后,再用50 mg/L ox-LDL刺激HUVEC,NF-κB p65 mRNA的表达下降25.61%(P＜0.01),分别用20、40、80 μmol/L的普罗布考干预后,NF-κB p65 mRNA的表达分别下调15.52%(P＜0.05)、24.92%(P＜0.01)、34.93%(P＜0.01);同时,Fractalkine mRNA的表达则分别下调32.22%(P＜0.01)、10.07%(P＞0.05)、20.59%(P＜0.01)、33.60%(P＜0.01).结论:ox-LDL可以通过NF-κB p65诱导HUVEC表达Fractalkine,而普罗布考则可以抑制Fractalkine的表达,这种作用可能与抑制NF-κB p65有关.     

PHF-2在氧化型低密度脂蛋白诱导THP-1源性

目的　观察氧化型低密度脂蛋白对THP-1巨噬细胞植物同源结构域指蛋白2（PHF-2）表达的影响,探讨表观遗传调节在氧化型低密度脂蛋白诱导巨噬细胞炎症反应中的作用。方法　用不同浓度（0、50、100、150　mg/L）氧化型低密度脂蛋白处理THP-1巨噬细胞4　h,采用酶联免疫吸附法检测肿瘤坏死因子α和巨噬细胞炎性蛋白1β的表达;采用实时荧光定量聚合酶链反应和Western　blot分别检测PHF-2　mRNA和蛋白质的表达;采用免疫共沉淀法检测PHF-2和p65核因子κB的结合。结果　100～150　mg/L氧化型低密度脂蛋白处理THP-1巨噬细胞4　h后,肿瘤坏死因子α和巨噬细胞炎性蛋白1β的表达明显上调;氧化型低密度脂蛋白呈浓度依赖性上调THP-1巨噬细胞PHF-2　mRNA和蛋白质的表达,并促进PHF-2和p65核因子κB的结合。结论　　PHF-2参与氧化型低密度脂蛋白诱导THP-1巨噬细胞核因子κB激活和炎症因子表达。     

核因子κB通过Sortilin促进荷脂THP-1巨噬细胞泡沫化

目的探究核因子κB(NF-κB)是否通过分拣蛋白Sortilin影响荷脂THP-1巨噬细胞脂质代谢和泡沫化。方法 NF-κB激活剂PMA或其特异性抑制剂PDTC孵育荷脂THP-1巨噬细胞,qRT-PCR检测Sortilin mRNA水平,Western blot检测Sortilin蛋白表达;沉默荷脂THP-1巨噬细胞Sortilin同时加入PMA孵育,胞内胆固醇流出行液体闪烁计数器检测,胞内脂质含量行高效液相色谱法检测,胞内脂滴情况用油红O染色显示。结果 PMA孵育处理荷脂THP-1巨噬细胞后Sortilin mRNA水平及蛋白表达上调,PDTC孵育处理后Sortilin mRNA水平及蛋白表达下调;PMA孵育处理荷脂THP-1巨噬细胞内脂质流出减少,脂质蓄积程度增加,泡沫细胞形成加剧,而PMA与Sortilin shRNA共处理后,其胞内脂质流出增多,胞内脂质蓄积程度减轻,泡沫细胞形成受抑。结论 NF-κB通过促进Sortilin表达,导致巨噬细胞内脂质流出受抑,胞内脂质蓄积程度加重,从而加剧泡沫细胞形成。     

硫化氢对THP-1源性巨噬细胞脂质摄取的影响

目的探索硫化氢对THP-1源性巨噬细胞脂质摄取的影响及可能机制。方法采用荧光显微镜测DiI标记的氧化型低密度脂蛋白(DiI-ox-LDL)摄取、RT-PCR和免疫印迹法测定CD36 mRNA和蛋白表达。结果巨噬细胞与DiI-ox-LDL孵育后大量摄取氧化型低密度脂蛋白(ox-LDL),外源性硫化氢供体硫氢化钠显著抑制巨噬细胞摄取氧化型低密度脂蛋白,而炔丙基甘氨酸(一个硫化氢产生酶胱硫醚-γ-裂解酶抑制剂)加剧巨噬细胞摄取氧化型低密度脂蛋白。进而,硫氢化钠呈浓度依赖性抑制巨噬细胞CD36 mRNA和蛋白表达,而炔丙基甘氨酸促进巨噬细胞CD36 mRNA和蛋白表达。结论硫化氢抑制巨噬细胞摄取脂质及清道夫受体CD36表达。     

高密度脂蛋白2和高密度脂蛋白3对THP-1巨噬细胞脂质蓄积及过氧化体增殖物激活型受体γ和CD36表达的影响

为探讨高密度脂蛋白2和高密度脂蛋白3对THP-1巨噬细胞过氧化体增殖物激活型受体γ和CD36表达及脂质蓄积的影响。取新鲜抗凝血浆，用超速离心术进行密度梯度离心，收集低密度脂蛋白、高密度脂蛋白2和3。将氧化型低密度脂蛋白分别与高密度脂蛋白2和3共孵育THP-1巨噬细胞，用油红O染色及高效液相分析法观测细胞内脂质蓄积程度；用逆转录聚合酶链反应检测CD36和过氧化体增殖物激活型受体γ mRNA的表达：用Westem blotting检测CD36和过氧化体增殖物激活型受体γ蛋白的表达。结果发现，与单独用氧化型低密度脂蛋白和THP-1孵育相比，用高密度脂蛋白2、高密度脂蛋白3分别与氧化型低密度脂蛋白共孵育THP-1可使细胞内脂质蓄积明显减少，过氧化体增殖物激活型受体γ mRNA及蛋白表达上调，CD36 mRNA及蛋白表达下调。而高密度脂蛋白3比高密度脂蛋白2作用更明显。结果提示，高密度脂蛋白2和3对氧化型低密度脂蛋白诱导THP-1细胞脂质蓄积有显著抑制作用，而高密度脂蛋白3的作用更强。其机制与高密度脂蛋白可以增强过氧化体增殖物激活型受体γ mRNA和蛋白表达上调及过氧化体增殖物激活型受体γ磷酸化，进而抑制过氧化体增殖物激活型受体γ的应答基因CD36 mRNA及蛋白表达有关。     

血管紧张素Ⅱ对巨噬细胞移动抑制因子mRNA表达的影响

目的探讨血管紧张素(Ang)Ⅱ是否能通过核因子(NF)-κB途径调节巨噬细胞移动抑制因子(MIF) mRNA的表达。方法佛波酯诱导THP-1细胞48 h并使其转化为巨噬细胞,用CD68进行免疫细胞化学鉴定。第一组:对照组、AngⅡ1×10~(-8)mol/L组、AngⅡ1×10~(-7)mol/L组、AngⅡ1×10-6mol/L组、AngⅡ1×10~(-5)mol/L组。第二组:对照组、AngⅡ(1×10(-6)mol/L)组、AngⅡ(1×10~(-6)mol/L)+吡咯烷二硫代氨基甲酸铵(PDTC)组、PDTC组。Western印迹方法检测第一组细胞核内NF-κB的表达。Real time RT-PCR方法检测第二组巨噬细胞MIF mRNA的表达。结果 Western印迹随着AngⅡ浓度的升高,NF-κBp65的表达逐渐增强。Real time RT-PCR:AngⅡ组MIF mRNA表达明显高于对照组;给予NF-κB特异性抑制剂PDTC后,由AngⅡ诱导的MIF mRNA表达明显降低。结论 AngⅡ能通过NF-κB信号通路促进巨噬细胞MIF mRNA的表达。     

Ox-LDL induces monocyte-to-macrophage differentiation in vivo: Possible role for the macrophage colony stimulating factor receptor (M-CSF-R)

Monocyte-to-macrophage differentiation and LDL oxidation play a pivotal role in early atherogenesis. We thus questioned possible mechanisms for oxidized LDL (Ox-LDL)-induced monocyte-to-macrophage differentiation in vivo. Mouse peritoneal mononuclear cells, that were isolated 1, 2, or 3 days after Ox-LDL intraperitoneal injection, gradually exhibited the characteristic macrophage morphology, along with the expression of the cell-surface antigen CD11b. Molecular mechanisms involved in Ox-LDL-induced differentiation were further investigated in vitro using the THP-1 monocytic cell line. THP-1 cells incubated with Ox-LDL in the presence of as low as 1 ng/ml of PMA differentiated into macrophages, as evidenced by morphologic, phenotypic, and functional properties. Stimulation of monocyte-to-macrophage differentiation was selective to Ox-LDL (and not native LDL), was dependent on the extent of LDL oxidation, and required Ox-LDL internalization by the cells. These effects of Ox-LDL could be attributed to its major oxysterols, 7-ketocholesterol and 7beta-hydroxycholesterol. Finally, the stimulation of monocyte differentiation to macrophages by Ox-LDL was shown to require the M-CSF-receptor, since blocking the binding to the receptor abolished Ox-LDL/7beta-hydroxycholesterol-induced differentiation. Furthermore, Ox-LDL/7beta-hydroxycholesterol elicited tyrosine phosphorylation and activation of the M-CSF-R. We thus conclude that Ox-LDL induces monocyte differentiation to macrophages in vivo and this phenomenon involves activation of the M-CSF-receptor.     

Uptake of oxidized low-density lipoprotein in a THP-1 cell line lacking scavenger receptor A

We previously isolated THP-1 subtype cells (sTHP-1), a cell line that expresses scanty amounts of scavenger receptor A (ScR-A) and does not undergo foam cell formation when incubated with acetylated low-density lipoprotein (Ac-LDL). In this study, we investigated the accumulation of esterified cholesterol in sTHP-1 cells incubated with oxidized LDL (Ox-LDL), a physiologically modified lipoprotein in human. While sTHP-1 cells incubated with Ac-LDL accumulated only small amounts of esterified cholesterol, those incubated with Ox-LDL accumulated amounts similar to those accumulated by parent THP-1 (pTHP-1) cells. sTHP-1 cells expressed CD36 in amounts similar to the amounts expressed by pTHP-1 cells, and Ox-LDL was internalized through this CD36. The amount of accumulated esterified cholesterol was 73-81% of that accumulated in pTHP-1 cells expressing ScR-A. The levels of 125I-Ox-LDL binding, association, and degradation in sTHP-1 cells were 64-70% of the corresponding levels in pTHP-1 cells. In our experiments utilizing ScR-A-deficient sTHP-1 cells and a specific antibody against human CD36, most of the Ox-LDL interacted with the CD36 receptor. In addition, a substantial amount of Ox-LDL (28-42%) was bound and degraded by sTHP-1 macrophages when both of the two major scavenger receptors, ScR-A and CD36, were deficient or blocked. These results indicate that CD36 in macrophages plays an important role in foam cell formation by Ox-LDL, while additional scavenger receptor(s) may take part in significant pathways of Ox-LDL uptake in macrophages.     

Oxidized LDL regulates vascular endothelial growth factor expression in human macrophages and endothelial cells through activation of peroxisome proliferator-activated receptor-gamma

Vascular endothelial growth factor (VEGF) has been recognized as an angiogenic factor that induces endothelial proliferation and vascular permeability. Recent studies have also suggested that VEGF can promote macrophage migration, which is critical for atherosclerosis. We have reported that VEGF is remarkably expressed in activated macrophages, endothelial cells, and smooth muscle cells within human coronary atherosclerotic lesions, and we have proposed the significance of VEGF in the progression of atherosclerosis. To clarify the mechanism of VEGF expression in atherosclerotic lesions, we examined the regulation of VEGF expression by oxidized low density lipoprotein (Ox-LDL), which is abundant in atherosclerotic arterial walls. A recent report has revealed that peroxisome proliferator-activated receptor-gamma (PPARgamma) is expressed not only in adipocytes but also in monocytes/macrophages and has suggested that PPARgamma may have a role in the differentiation of monocytes/macrophages. Furthermore, 9- and 13-hydroxy-(S)-10,12-octadecadienoic acid (9- and 13-HODE, respectively), the components of Ox-LDL, may be PPARgamma ligands. Therefore, we investigated the involvement of PPARgamma in the regulation of VEGF by Ox-LDL. PPARgamma expression was detected in human monocyte/macrophage cell lines, human acute monocytic leukemia (THP-1) cells, and human coronary artery endothelial cells (HCAECs). Ox-LDL (10 to 50 microg/mL) upregulated VEGF secretion from THP-1 dose-dependently. VEGF mRNA expression in HCAECs was also upregulated by Ox-LDL. The mRNA expression of VEGF in THP-1 cells and HCAECs was also augmented by PPARgamma activators, troglitazone (TRO), and 15-deoxy-(12,14)-prostaglandin J(2) (PGJ2). In contrast, VEGF expression in another monocyte/macrophage cell line, human histiocytic lymphoma cells (U937), which lacks PPARgamma expression, was not augmented by TRO or PGJ2. We established the U937 cell line, which permanently expresses PPARgamma (U937T). TRO and Ox-LDL augmented VEGF expression in U937T. In addition, VEGF production by THP-1 cells was significantly increased by exposure to 9-HODE and 13-HODE. In conclusion, Ox-LDL upregulates VEGF expression in macrophages and endothelial cells, at least in part, through the activation of PPARgamma.     

泡沫细胞形成过程中酰基CoA:胆固醇酰基转移酶1活性改变及其机制研究

目的　研究人单核细胞系在分化为巨噬细胞及转化为泡沫细胞过程中酰基CoA :胆固醇酰基转移酶 1(ACAT1)活性的改变及其机制。方法　体外培养人THP 1单核细胞系 ,由佛波酯作用使其分化为巨噬细胞 ,后者再由氧化低密度脂蛋白 (Ox LDL)进一步作用转变为泡沫细胞。此过程中以放射性同位素标记底物法检测ACAT1活性的变化 ,并用Westernblot法检测ACAT1蛋白的表达及RT PCR法检测ACAT1mRNA的水平。结果　在单核细胞分化为巨噬细胞的过程中ACAT1活性升高了 2倍 ,差异具有显著性 (P <0 0 5 ) ,酶蛋白及mRNA水平呈现类似变化趋势 ,在进一步转化为泡沫细胞过程中 ,ACAT1活性、酶蛋白及mRNA仍处于较高水平 ,但与巨噬细胞相比差异无显著性。结论　单核细胞分化为巨噬细胞的过程中ACAT1转录水平的上调导致酶蛋白量合成增加 ,从而使ACAT1活性也大为增强 ,而Ox LDL对ACAT1活性影响则不明显。     

Effect of probucol on macrophages, leading to regression of xanthomas and atheromatous vascular lesions

To explain the strong effect of probucol on xanthomas, the drug's effect on lipid storage in macrophages in the presence of denatured low-density lipoprotein (LDL) was studied. Two macrophage cell lines, UE-12 and THP-1, were used. Those cells stored lipids and became foam cells when they were incubated with acetylated LDL (acetyl-LDL). When probucol was added into the medium either in ethanolic solution or in the form bound to LDL, the storage of cholesterol and other lipids and the development of macrophages into foam cells were greatly suppressed. Two functions of probucol should be considered: (1) It inhibited the uptake of acetyl-LDL by macrophages; and (2) it enhanced the release of cholesterol from these cells. Cells were first incubated with probucol. After the cells were washed with fresh medium, the radiolabeled acetyl-LDL was added to the medium and the degradation of acetyl-LDL was measured. Increasing the concentration of probucol led to a decrease in degradation of acetyl-LDL by macrophages. Probucol also suppressed the uptake of albumin. Macrophages were incubated with acetyl-LDL, washed once, then incubated with or without probucol and high-density lipoprotein (HDL). Addition of HDL caused a rapid decrease in cholesterol content in the cells, and this phenomenon was enhanced by probucol for both kinds of cells. The secretion of apolipoprotein E was also stimulated by the addition of probucol. These 2 sets of experimental results suggest that probucol prevents lipid storage in macrophages by both suppressing the uptake and stimulating the release of cholesterol and other lipids into or from the macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)     

C反应蛋白和高密度脂蛋白对血凝素样氧化型低密度脂蛋白受体1表达的影响

目的观察C反应蛋白和高密度脂蛋白对单核细胞株THP-1来源的巨噬细胞血凝素样氧化型低密度脂蛋白受体1蛋白和mRNA表达的影响,以及血凝素样氧化型低密度脂蛋白受体1表达的变化与细胞内胆固醇含量变化的关系。方法THP-1单核细胞株经佛波酯诱导分化为巨噬细胞。用不同浓度C反应蛋白或高密度脂蛋白在体外干预巨噬细胞,测定干预前后巨噬细胞血凝素样氧化型低密度脂蛋白受体1蛋白和mRNA表达的变化,并采用高效液相色谱测定巨噬细胞内胆固醇含量的变化。结果与对照组相比,C反应蛋白或高密度脂蛋白均可以诱导THP-1来源的巨噬细胞血凝素样氧化型低密度脂蛋白受体1蛋白和mRNA表达增加(P<0.05),C反应蛋白使巨噬细胞内总胆固醇和胆固醇酯含量显著增加(P<0.01),而高密度脂蛋白使细胞内总胆固醇和胆固醇酯显著降低(P<0.01)。结论C反应蛋白和高密度脂蛋白都能引起THP-1来源的巨噬细胞表面血凝素样氧化型低密度脂蛋白受体1表达上调,提示血凝素样氧化型低密度脂蛋白受体1并不是介导巨噬细胞参与炎症反应病理生理变化的关键性受体。     

NO/PKG对THP-1巨噬细胞ABCA1基因mRNA表达和胆固醇含量的影响

目的:探讨THP-1巨噬细胞泡沫化过程中NO/PKG的变化,以及NO/PKG对THP-1巨噬细胞ATP结合盒转运体A1(ABCA1)基因mRNA表达和胆固醇含量的影响。方法:THP-1细胞诱导分化为巨噬细胞,用氧化低密度脂蛋白(ox-LDL)处理,油红O染色观察巨噬细胞脂滴,酶标仪测定一氧化氮(NO)的释放;用一氧化氮供体L-精氨酸和硝普钠(SNP)、乙二醇二乙醚二胺四乙酸(EGTA)、PKG激动剂处理巨噬细胞,RT-PCR法测定细胞ABCA1基因mRNA的表达,高效液相色谱法(HPLC)测定细胞内胆固醇的含量变化。结果:ox-LDL可导致THP-1巨噬细胞脂质的蓄积和NO释放的增加,实验组NO释放量较对照组显著升高(P<0.05),实验组中50mg/L组、100mg/L组、200mg/L组与25mg/L组相比显著升高(P<0.05)。用PKG激动剂处理巨噬细胞后促进ABCA1基因mRNA表达上调(P<0.05);用PKG激动剂、L-精氨酸、SNP处理后的巨噬细胞内胆固醇较对照组显著减少(P<0.05)。EGTA能显著增加细胞内胆固醇含量(P<0.05)。结论:NO/PKG能降低细胞内胆固醇,其机制可能是PK...     

Lovastatin inhibits low-density lipoprotein oxidation and alters its fluidity and uptake by macrophages: in vitro and in vivo studies.

Under experimental conditions, oxidized low-density lipoprotein (Ox-LDL) may possess atherogenic properties, as is evidenced by its contribution to cholesterol accumulation in macrophages. LDL was oxidized in a cell-free system by predialysis of the lipoprotein against EDTA-free buffer and the addition of copper ions. Oxidation of LDL in the presence of lovastatin (10 to 1,000 mumol/L) resulted in a time- and dose-dependent reduction in thiobarbituric-acid-reactive substances (TBARS) concentration that was accompanied by increased LDL lysine-amino-group reactivity, in comparison with Ox-LDL produced in the absence of lovastatin. At 100 mumol/L, the drug reduced malondialdehyde concentration and increased amino-group reactivity by 24% and 42%, respectively. However, lovastatin's antioxidant effect was limited relative to other antioxidants, such as probucol and vitamin E. The fluidity of Ox-LDL was substantially reduced in comparison with native LDL. However, lovastatin inhibited this reduction in fluidity by 20%. Upon incubation of J-774 macrophage-like cell line with Ox-LDL, the lovastatin-treated Ox-LDL induced a reduction in the cellular cholesterol esterification rate in comparison with the effect of Ox-LDL that was produced in the absence of the drug. In four patients with hypercholesterolemia, the effect of lovastatin therapy (20 mg/d) on the sensitivity of their LDL to in vitro oxidation was studied. In all patients, Ox-LDL prepared from LDL obtained during lovastatin treatment demonstrated a reduced TBARS content, an increased trinitrobenzenesulfonic acid (TNBS) reactivity, an increased fluidity, and an impaired uptake by macrophages. These results were similar to those obtained by adding lovastatin in vitro.     

Retention of oxidized LDL by extracellular matrix proteoglycans leads to its uptake by macrophages: an alternative approach to study lipoproteins cellular uptake

Interaction between arterial macrophages and oxidized LDL (Ox-LDL) leads to foam cell formation, a critical step during early atherogenesis. Until now, cellular uptake of lipoproteins was studied through incubation of the media-soluble lipoprotein with cultured macrophages. However, as lipoproteins in the arterial wall are bound to subendothelial matrix, we questioned whether the retention (binding) of Ox-LDL to a macrophage-derived extracellular matrix (ECM) could lead to enhanced uptake by macrophages. The uptake of ECM-bound Ox-LDL by activated macrophages (by phorbol myristate acetate) was lipoprotein dose dependent, time dependent and higher (by 1.5-fold) than the uptake of ECM-bound native LDL. Preincubation of the ECM with lipoprotein lipase before the addition of Ox-LDL was essential for the uptake of ECM-bound Ox-LDL by the macrophages. After radiolabeling of the ECM glycosaminoglycans (GAGs), we found that ECM-bound Ox-LDL is taken up by the macrophages together with the ECM-GAG. Finally, these results were further confirmed through the use of ECM obtained from mouse peritoneal macrophages (MPMs), derived from atherosclerotic, apoE-deficient mice. In 24-week-old mice with developed atherosclerosis, the GAG content of their MPM-derived ECM increased by 52%, the ability of their MPM-derived ECM to bind Ox-LDL increased by 57%, and macrophage uptake of Ox-LDL that was retained by the MPM-derived ECM increased by 86%. In conclusion, the present study demonstrated that ECM-bound Ox-LDL is taken up by activated macrophages. This may represent a physiopathological phenomenon that leads to cholesterol and oxysterol accumulation in arterial macrophages, the hallmark of early atherosclerosis.