PPARγ激动剂对RAW264.7巨噬细胞源性泡沫细胞胆固醇流出的影响

目的观察PPARγ激动剂吡格列酮对RAW264.7巨噬细胞源性泡沫细胞胆固醇流出调节蛋白三磷酸腺苷结合核转运蛋白G1(ABCG1)、肝X受体α(LXRα)表达的影响。方法 (1)体外培养RAW 264.7巨噬细胞,用50 mg/L的氧化型低密度脂蛋白胆固醇(ox-LDL)孵育48 h诱导成泡沫细胞,油红O染色并在光镜下鉴定泡沫细胞形态及变化。(2)以不同浓度吡格列酮(0、5、10、20、30μmol/L)作用泡沫细胞24 h后,酶法检测泡沫细胞内胆固醇酯的含量。用反转录-聚合酶链反应(RT-PCR)及免疫印迹法测定ABCG1、LXRα的mRNA及蛋白的表达。结果 PPARγ激动剂吡格列酮可显著减少泡沫细胞内胆固醇酯含量,并呈浓度依赖性增加RAW264.7巨噬细胞源性泡沫细胞ABCG1、LXRα的mRNA和蛋白的表达。结论 PPARγ激动剂吡格列酮减少泡沫细胞内胆固醇酯的含量可能是通过上ABCG1、LXRα的mRNA及蛋白表达来实现的。     

载脂蛋白嵌合模拟肽对低密度脂蛋白诱导的巨噬细胞凋亡的影响

目的观察模拟肽Ac-hE-18A-NH2对氧化低密度脂蛋白(oxLDL)诱导的RAW264.7巨噬细胞凋亡的影响。方法50 mg.L-1oxLDL处理RAW 264.7细胞48 h后加入不同浓度的Ac-hE-18A-NH2(1、10、50、100 mg.L-1)和β-环糊精(β-CD)或布雷菲得菌素(BFA)共同孵育24 h。通过流式细胞仪检测细胞凋亡,试剂盒检测caspase-3活性及细胞内胆固醇含量,Western blot检测细胞bcl-2蛋白的表达,液体闪烁计数器检测细胞内胆固醇流出。结果 oxLDL诱导的RAW 264.7巨噬细胞的凋亡率随着oxLDL浓度的增加和处理时间的延长而明显提高。Ac-hE-18A-NH2(1、10、50、100mg.L-1)干预后细胞凋亡率以浓度依赖的方式减少。Ac-hE-18A-NH2呈浓度依赖性的促进细胞内胆固醇流出和降低细胞内的胆固醇含量,降低caspase-3的活性,上调bcl-2的蛋白表达。β-CD与Ac-hE-18A-NH2共同作用后胆固醇流出明显增加,细胞凋亡率相应减少。而BFA作用相反。结论Ac-hE-18A-NH2明显抑制oxLDL诱导的巨噬细胞凋亡,其作用可能与促进细胞胆固醇流出、减少细胞内胆固醇蓄积有关。     

肝X受体激动剂对RAW 264.7细胞ABCA1蛋白表达和TNF-α、IL-6产生和分泌的影响

目的:研究肝X受体激动剂3β-羟基-5α,6α-环氧胆烷酸甲酯和(MHEC)T-0901317对小鼠巨噬细胞株RAW264.7细胞三磷酸腺苷结合盒转运体A1(ABCA1)蛋白表达和TNF-α、IL-6产生和分泌的影响.方法:应用免疫细胞化学染色法检测RAW264.7细胞ABCA1蛋白表达的影响;应用夹心法ELISA检测细胞培养上清液中TNF-α和IL-6的浓度,分析肝X受体激动剂对氧化低密度脂蛋白(ox-LDL)诱导的巨噬细胞TNF-α、IL-6产生和分泌的影响.结果:3β-羟基-5α,6α-环氧胆烷酸甲酯和T-0901317均可显著促进RAW264.7细胞ABCA1蛋白的表达;与维甲酸X受体激动剂9-顺式视黄酸联合作用时,ABCA1蛋白表达增加更为显著.氧化低密度脂蛋白可促进RAW264.7细胞TNF-α、IL-6的产生和分泌,而这一促进作用可部分地被3β-羟基-5α,6α-环氧胆烷酸甲酯和T-0901317所抑制.结论:肝X受体激动剂MHEC和T-0901317均可上调RAW264.7细胞ABCA1蛋白表达,并可减少氧化低密度脂蛋白诱导的巨噬细胞中TNF-α、IL-6的产生和分泌.     

PPARγ对RAW264.7小鼠巨噬细胞异质性的影响

目的 探讨PPAR γ对缺氧复氧RAW264.7小鼠巨噬细胞异质性的影响.方法 体外培养小鼠巨噬细胞系(RAW264.7),制备缺氧复氧模型,用慢病毒包装进行PPARγ过表达和基因沉默,细胞分为对照组、模型组、过表达PPARγ组和PPARγ基因沉默组.用ELISA法、RT-PCR、Western印迹法和免疫荧光法检测各组细胞巨噬细胞亚型M1标志物诱导型一氧化氮合酶(iNOS)、M2标志物CD206及肿瘤坏死因子-α(TNF-α)、干扰素-γ(IFN-γ)的表达.结果 与对照组相比,ELISA法检测模型组TNF-α和IFN-γ水平明显升高(均P＜0.01),RT-PCR、Western印迹法和免疫荧光检测均显示TNF-α、IFN-γ、iNOS表达上调,CD206表达下调.与模型组相比,过表达PPARγ显著减轻了IRI导致的TNF-α、IFN-γ和iNOS表达的上调,上调了CD206表达;与此相反,PPARγ基因沉默加重IRI导致TNF-α、IFN-γ和iNOS表达上调,下调了CD206表达.结论 PPARγ在小鼠RAW264.7巨噬细胞缺氧复氧模型中参与调节巨噬细胞表型转换.     

Rolipram对THP-1巨噬细胞源性泡沫细胞胆固醇流出和ABCA1表达的影响

目的　以THP 1巨噬细胞源性泡沫细胞为研究对象 ,探讨磷酸二酯酶抑制剂rolipram对THP 1巨噬细胞源性泡沫细胞ABCA1表达及细胞内胆固醇流出的影响。方法　用液体闪烁计数器检测细胞内胆固醇流出 ,运用逆转录 -多聚酶链反应和Westernblot印迹分别检测ABCA1mRNA与ABCA1蛋白的表达 ,采用低pH值EIA法测定细胞内cAMP水平。结果　实验显示PDE4抑制剂rolipram能引起THP 1巨噬细胞源性泡沫细胞cAMP水平、ABCA1表达和apoA 1介导的胆固醇流出成平衡增加 ,而细胞内总胆固醇、游离胆固醇与胆固醇酯明显减少。结论　PDE4抑制剂rolipram增加THP 1巨噬细胞源性泡沫细胞ABCA1表达及细胞内胆固醇流出 ,这为防治动脉粥样硬化发生发展提供一个新的策略     

苯扎贝特对THP1巨噬细胞PPARγ及ABCA1表达的影响

目的 探讨苯扎贝特对THP1巨噬细胞PPARγ及ABCA1表达的影响.方法 THP1细胞经PMA诱导24h后,添加不同浓度苯扎贝特(0、1、10、50μmol/L)继续作用24h,RT-PCR法测定PPARγ、ABCA1 mRNA表达.结果 PMA刺激THP1细胞表达PPARγ及ABCA1;苯扎贝特剂量依赖性上调THP-1巨噬细胞PPARγ及ABCA1的表达(P＜0.05),50μmol/L浓度时二者表达最高,且PPARγ与ABCA1的mRNA表达呈正相关(r=0.628,P=0.002).结论 苯扎贝特上调THP1细胞中PPARγ和ABCA1的表达.     

化合物E0869体外抗动脉粥样硬化的活性研究

ATP结合盒转运体A1(ATP-binding cassette transporter A1,ABCA1)和清道夫受体B型I(scavenger receptor class B type I,SR-BI/CLA-1)是胆固醇逆转运过程中的重要蛋白。ABCA1和SR-BI/CLA-1的高表达能降低动脉粥样硬化的危险性。因此,本研究利用前期已建立的人ABCA1和CLA-1表达上调剂筛选模型,对20 000个化合物进行筛选,获得能上调ABCA1和CLA-1表达的化合物E0869[4-甲磺酰甲基苯甲酸-1-(3,4-二甲基苯基)-1-丙酮-2-酯],其上调活性分别为160%和175%,EC50值分别为3.79和1.42μmol·L-1;进一步研究发现,活性化合物E0869能上调肝细胞Hep G2以及巨噬细胞RAW264.7中ABCA1、SR-BI/CLA-1以及ABCG1的m RNA和蛋白水平,但不影响FAS、SREBP-1c、CD36的表达;E0869能使泡沫化巨噬细胞RAW264.7胞内脂滴量明显减少,并能增加其胆固醇的流出。因此,化合物E0869能够上调ABCA1和CLA-1活性,并且具有较好的体外抗动脉粥样硬化效果。     

尼古丁对巨噬细胞肝X受体α表达及胆固醇外流的影响

目的通过研究尼古丁对巨噬细胞的肝X受体α(LXRα)及其下游的一些目的基因表达和胆固醇外流的影响,探讨尼古丁对LXR信号系统的作用。方法分离人外周血单核细胞,并转化为巨噬细胞。在尼古丁的作用下,观察巨噬细胞的aopA-Ⅰ介导的胆固醇外流的变化和LXR以及其下游一些目的基因mRNA表达。结果尼古丁明显影响巨噬细胞中一些涉及胆固醇代谢及炎症反应的基因表达,同时降低aopA-Ⅰ介导的胆固醇外流。结论巨噬细胞在尼古丁的作用下,由aopA-Ⅰ介导的胆固醇外流降低,这种效应与尼古丁下调LXRα及其下游的影响胆固醇代谢的目的基因有关,同时,也促进一些炎症因子基因的表达。提示尼古丁在动脉粥样硬化中的作用与其影响巨噬细胞LXR信号途径有关,从而影响泡沫细胞的形成。     

二氢杨梅素对巨噬细胞源性泡沫细胞胆固醇流出的影响

摘要：目的 观察二氢杨梅素 （DMY） 对鼠源巨噬细胞性泡沫细胞胆固醇流出的影响并探讨其可能机制。方法 用 50 mg/L 的氧化低密度脂蛋白 （ox-LDL） 孵育鼠源性巨噬细胞 RAW264.7 经 48 h 诱导细胞泡沫化。将泡沫细胞分为对照组 （只加 RPMI 1640 的培养基培养） 和 DMY1~4 组 （分别用 10、 20、 40 和 80 μmol/L DMY 处理）, 培养 24 h。采用[ 3 H]标记的胆固醇检测细胞胆固醇的流出率, 高效液相色谱测定细胞内游离胆固醇 （FC）、 胆固醇酯 （CE） 和总胆固醇 （TC） 的水平, Western blot 检测细胞中三磷酸腺苷结合盒转运体 A1 （ABCA1） 的表达。结果 与对照组比较, 20、 40 和 80 μmol/L DMY 组细胞的胆固醇流出率均显著增加, 细胞内 FC、 TC 和 CE 水平及 CE/TC 的比值均显著减少, ABCA1 的表达显著上调, 均呈剂量依赖性 （均 P < 0.05）。与对照组比较, DMY （10 μmol/L） 组细胞胆固醇流出率,细胞内 FC、 TC 和 CE 水平,ABCA1 的表达差异均无统计学意义 （均 P > 0.05）。结论 DMY 促进了鼠源巨噬细胞性泡沫细胞胆固醇流出, 其机制可能与上调泡沫细胞中 ABCA1的表达有关。 ,     

Valsartan and telmisartan abrogate angiotensin II-induced downregulation of ABCA1 expression via AT1 receptor, rather than AT2 receptor or PPARγ activation

The possible pharmacological mechanism by which partial PPARγ-activating angiotensin II (Ang II) type 1 receptor blocker (ARB) telmisartan and non-PPARγ-activating ARB valsartan reverse Ang II-suppressed ABCA1 expression is still unclear. In this study, human monocyte-derived THP-1 cells were differentiated into macrophages. Cells were treated with various concentrations of Ang II alone or with Ang II and various drugs including highly selective ARB valsartan, partial PPARγ-activating ARB telmisartan, angiotensin II type 2 (AT2) receptor blocker PD123319, full PPARγ agonist pioglitazone, and PPARγ antagonist GW9662, respectively. After treatment, messenger RNA and protein expressions of ABCA1 and ABCG1 were analyzed by real-time polymerase chain reaction and Western blotting, respectively. ABCA1 expression was remarkably suppressed by Ang II at both messenger RNA and protein levels in a dose-dependent manner in THP-1-derived macrophages, whereas ABCG1 expression was not affected. Valsartan and telmisartan could both reverse the downregulation of Ang II on ABCA1 expression. Such effects were not affected by either AT2 receptor blocker PD123319 or PPARγ antagonist GW9662. Our findings suggest that the effect of Ang II on ABCA1 expression should be mediated by the AT1 receptor. Both valsartan and telmisartan abrogate Ang II-induced downregulation of ABCA1 expression mainly through AT1 receptor rather than through AT2 receptor or PPARγ-dependent pathway.     

Tributyltin chloride induces ABCA1 expression and apolipoprotein A-I-mediated cellular cholesterol efflux by activating LXRα/RXR

Organotins, including tri-butyltin chloride (TBTC), are widely used in agricultural and chemical industries and cause persistent and widespread pollution. TBTC has been shown to activate nuclear receptor retinoid X receptor (RXR)/PPARγ signaling by interacting with RXR to modulate adipogenesis. However, whether TBTC affects liver X receptor (LXR)/RXR activity and subsequently the expression of cholesterol mobilizing genes is not known. In this study, we evaluated the ability of TBTC to activate LXR/RXR and ABC transporter A1 (ABCA1) expression. ABCA1 plays a critical role in HDL generation, maintaining cholesterol homeostasis, and cholesterol accumulation-induced diseases, such as atherosclerosis and pancreatic islet dysfunction. In a reporter gene assay, TBTC activated LXRα/RXR but not LXRβ/RXR. In mouse macrophage RAW264 cells, TBTC activated the ABCA1 promoter in an LXR-responsive element dependent manner and increased ABCA1 mRNA expression. TBTC augmented ABCA1 protein levels and apolipoprotein A-I-dependent cellular cholesterol efflux (HDL generation). The LXR-target fatty acid synthase and Spα mRNA levels were also increased by TBTC exposure. We conclude that TBTC has the ability to activate permissive LXRα/RXR signaling and thereby modulate cellular cholesterol efflux.     

Tributyltin chloride induces ABCA1 expression and apolipoprotein A-I-mediated cellular cholesterol efflux by activating LXRalpha/RXR

Organotins, including tri-butyltin chloride (TBTC), are widely used in agricultural and chemical industries and cause persistent and widespread pollution. TBTC has been shown to activate nuclear receptor retinoid X receptor (RXR)/PPARγ signaling by interacting with RXR to modulate adipogenesis. However, whether TBTC affects liver X receptor (LXR)/RXR activity and subsequently the expression of cholesterol mobilizing genes is not known. In this study, we evaluated the ability of TBTC to activate LXR/RXR and ABC transporter A1 (ABCA1) expression. ABCA1 plays a critical role in HDL generation, maintaining cholesterol homeostasis, and cholesterol accumulation-induced diseases, such as atherosclerosis and pancreatic islet dysfunction. In a reporter gene assay, TBTC activated LXRα/RXR but not LXRβ/RXR. In mouse macrophage RAW264 cells, TBTC activated the ABCA1 promoter in an LXR-responsive element dependent manner and increased ABCA1 mRNA expression. TBTC augmented ABCA1 protein levels and apolipoprotein A-I-dependent cellular cholesterol efflux (HDL generation). The LXR-target fatty acid synthase and Spα mRNA levels were also increased by TBTC exposure. We conclude that TBTC has the ability to activate permissive LXRα/RXR signaling and thereby modulate cellular cholesterol efflux.     

Oxidized LDL upregulated ATP binding cassette transporter-1 in THP-1 macrophages

INTRODUCTIONOxidized lipid signaling in macrophages is centralto the pathogenesis of atherosclerosis[1]. Exposure ofmacrophages and other vascular cells to oxidized low-density lipoprotein (ox-LDL) leads to complex changesin gene expression that are collectively thought to influ-ence the development of the atherosclerotic lesion[2].Using two-dimensional gel electrophoresis, the overallprotein map in U937 control cells and U937 foam cellswas obtained. Compared with U937 cells, 37 spots…     

ATP-binding cassette transporters in macrophages: promising drug targets for treatment of cardiovascular disease

Numerous ATP-binding cassette (ABC) transporters are expressed in monocyte-derived macrophages and are subject to sterol-dependent regulation. ABCA1 has been identified as a key regulator of macrophage cholesterol efflux and HDL-mediated reverse cholesterol transport. Although the precise mechanisms of ABCA1 function are not completely understood, recent data suggest that the ABCA1 pathway regulates vesicular traffic, filipodia formation and lipid microdomains, thereby controlling susceptibility to atherosclerosis. Nuclear hormone receptors including LXR/RXR and PPAR/RXR heterodimers are recognized as direct or indirect regulators of ABCA1 expression and are discussed as potential targets for pharmacological intervention in cardiovascular disease. Future studies clarifying the processes involved in the ABCA1 pathway at the cellular level are expected to identify new and possibly more specific pharmaceutical targets.     

Angiotensin‐(1–7) upregulates expression of adenosine triphosphate‐binding cassette transporter A1 and adenosine triphosphate‐binding cassette transporter G1 through the Mas receptor through the liver X receptor alpha signalling pathway in THP‐1 macrophages treated with angiotensin‐II

Adenosine triphosphate‐binding cassette transporter A1 (ABCA1) and ABCG1 play crucial roles in reverse cholesterol transport, and have anti‐atherosclerosis effects, and liver X receptor alpha (LXRα) can stimulate cholesterol efflux through these transporters. Angiotensin (Ang)‐(1–7) can protect endothelial cells, inhibit smooth muscle cell growth, ameliorate inflammation and exert anti‐atherosclerotic effects. In the present study, we attempted to clarify the effect of Ang‐(1–7) on expression of ABCA1 and ABCG1, and explored the role of LXRα in the regulation of ABCA1 and ABCG1 in THP‐1 macrophages that had been incubated with angiotensin‐II (AngII). Ang‐(1–7) increased ABCA1 and ABCG1 expression in a concentration‐dependent manner at both the mRNA and protein levels, promoted cholesterol efflux, and decreased cholesterol content in THP‐1 macrophages treated with AngII. Furthermore, Ang‐(1–7) upregulated the expression of LXRα in a concentration‐dependent manner in these cells. LXRα small interfering RNA, as well as the Mas receptor antagonist A‐779, completely abolished these effects of Ang‐(1–7). In summary, Ang‐(1–7) upregulates ABCA1 and ABCG1 expression in THP‐1 macrophages treated with AngII through the Mas receptor, via the LXRα pathway. This novel insight into the molecular mechanism underlying Ang‐(1–7) and AngII interaction could prove useful for developing new strategies for treatment of cardiovascular diseases.     

Selective activation of liver X receptors by acanthoic acid-related diterpenes

Terpenoids constitute a large family of natural steroids that are widely distributed in plants and insects. We investigated the effects of a series of diterpenes structurally related to acanthoic acid in macrophage functions. We found that diterpenes with different substitutions at the C4 position in ring A are potent activators of liver X receptors (LXRalpha and LXRbeta) in both macrophage cell lines from human and mouse origin and primary murine macrophages. Activation of LXR by these diterpenes was evaluated in transient transfection assays and gene expression analysis of known LXR-target genes, including the cholesterol transporters ABCA1 and ABCG1, the sterol regulatory element-binding protein 1c, and the apoptosis inhibitor of macrophages (Spalpha). Moreover, active diterpenes greatly stimulated cholesterol efflux from macrophages. It is interesting that these diterpenes antagonize inflammatory gene expression mainly through LXR-dependent mechanisms, indicating that these compounds can activate both LXR activation and repression functions. Stimulation of macrophages with acanthoic acid diterpenes induced LXR-target gene expression and cholesterol efflux to similar levels observed with synthetic agonists 3-[3-[N-(2-chloro-3-trifluoromethylbenzyl)-(2,2-diphenylethyl)-amino]propyloxy]phenylacetic acid hydrochloride (GW3965) and N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)-ethyl]phenyl]-benzenesulfonamide [T1317 (T0901317)]. These effects observed in gene expression were deficient in macrophages lacking both LXR isoforms (LXRalpha,beta(-/-)). These results show the ability of certain acanthoic acid diterpenes to activate efficiently both LXRs and suggest that these compounds can exert beneficial effects from a cardiovascular standpoint through LXR-dependent mechanisms.