髓样细胞表达的触发受体1抑制LPS应激下巨噬细胞的自噬

目的　观察髓样细胞表达的触发受体1（TREM-1）对脂多糖（LPS）应激下巨噬细胞自噬相关基因表达的影响。 方法　观察LPS应激下的巨噬细胞TREM-1蛋白的表达。分别选用TREM-1的激动剂（MAB1187）和TREM-1的拮抗剂（LR12）作用于巨噬细胞,利用qPCR检测巨噬细胞自噬相关基因ATG7、ATG5、ATG12及自噬标志蛋白微管相关蛋白1轻链3（LC3）mRNA的表达;采用Western Blot检测巨噬细胞TREM-1、LC3Ⅱ/Ⅰ、ATG7蛋白的表达;采用免疫荧光检测在LPS应激与TREM-1激活的情况下,巨噬细胞的自噬标志蛋白LC3表达。 结果　LPS（400 ng/mL、1000 ng/mL）应激下巨噬细胞TREM-1蛋白表达明显增加;LPS（1000 ng/mL）作用巨噬细胞24 h,巨噬细胞TREM-1蛋白表达达到峰值。LPS应激的巨噬细胞自噬基因ATG7、ATG5、ATG12及自噬标志分子LC3 mRNA表达均降低;当给予TREM-1拮抗剂后,巨噬细胞的ATG7、ATG5、ATG12、LC3 mRNA表达均升高,而采用TREM-1激动剂后,自噬基因表达被抑制。Western Blot检测结果显示,TREM-1可抑制LPS应激下巨噬细胞LC3 Ⅱ/Ⅰ、ATG7蛋白的表达。免疫荧光检测表明TREM-1激动剂可使巨噬细胞胞内的LC3蛋白表达量减少。 结论　巨噬细胞胞膜上TREM-1激活后,可使巨噬细胞自噬减弱,提示LPS应激下的巨噬细胞TREM-1可能通过抑制巨噬细胞的正常自噬从而发挥炎症放大作用。     

脂多糖诱导的小鼠腹腔巨噬细胞基因表达谱分析

目的　利用基因芯片技术分析脂多糖 (LPS)活化的小鼠腹腔巨噬细胞基因表达谱 ,以更全面地了解LPS诱导的巨噬细胞反应。方法　以未刺激的和用 1mg/LLPS刺激的小鼠腹腔巨噬细胞制备3 3 P标记的cDNA探针 ,分别与含有 1176个已知基因的小鼠cDNA芯片杂交。结果　活化组和未刺激组间的 2倍差异表达基因为 118个 ,3倍差异表达基因为 6 9个 ,其中 4 4个上调 ,2 5个下调。转录因子、细胞内信号调节蛋白、炎症细胞因子和细胞凋亡相关基因的转录发生明显的调节变化。结论提供了LPS活化的巨噬细胞综合基因表达信息 ,并筛选出一些新的可能与LPS活化相关的基因。     

IGF-1R、p-ERK参与低密度脂蛋白诱导小鼠腹腔巨噬细胞存活（英文）

目的:研究低密度脂蛋白对小鼠腹腔巨噬细胞胰岛素样生长因子-1受体(IGF-1R)、磷酸化细胞外信号调节激酶(p-ERK)、Bcl-2和Bax表达的影响,从而探讨低密度脂蛋白诱导巨噬细胞存活的机理。方法:应用免疫细胞化学和Western blotting方法,检测低密度脂蛋白对小鼠腹腔巨噬细胞IGF-1R、p-ERK、Bcl-2和Bax表达的影响。结果:氧化型低密度脂蛋白(oxLDL)以剂量和时间依赖的方式增加IGF-1R的表达。oxLDL刺激5min后,p-ERK表达最高。oxLDL诱导ERK从细胞浆内转至胞核内。给予IGF-1R抗体后,oxLDL诱导p-ERK表达降低,并且ERK转核过程消失。oxLDL以浓度和时间依赖的方式增加Bcl-2的表达,降低Bax的表达。给予ERK抑制剂PD98059后,oxLDL诱导Bcl-2表达降低,而Bax蛋白表达明显增高。自然型LDL对这4种蛋白的表达无明显影响。结论:oxLDL诱导巨噬细胞存活至少是通过增加IGF-1R的表达及ERK磷酸化实现的,并且可能存在其他的途径参与oxLDL诱导巨噬细胞存活。     

心肌细胞氧化损伤对myocardin和核因子E2相关因子2的影响

利用过氧化氢(H_2O_2)建立大鼠心肌细胞氧化损伤模型;观察心肌细胞氧化损伤过程中myocardin和核因子E2相关因子2(Nrf2)的表达变化并初步探讨myocardin对Nrf2的影响。通过转染质粒过表达目的基因,转染sh RNA质粒下调目的基因表达;通过磺酰罗丹明B(SRB)比色法检测细胞增殖,通过Real-time PCR检测mRNA的表达,通过Western blot检测蛋白的表达。结果显示200μmol/L H_2O_2孵育24 h为最佳H_2O_2氧化损伤条件;H_2O_2抑制myocardin mRNA及蛋白的表达,同时增加Nrf2 mRNA及蛋白的表达;过表达myocardin基因或者下调Nrf2基因后相对活细胞数较对照组明显减少,而下调myocardin基因或者上调Nrf2基因后相对活细胞数较对照组明显增多;过表达myocardin基因后检测到Nrf2 mRNA和蛋白表达出现明显下调,而下调myocardin基因后检测到Nrf2 mRNA和蛋白表达明显上调。因此推断myocardin基因可能抑制细胞增殖,而Nrf2基因可能促进细胞增殖;H_2O_2造成大鼠心肌细胞氧化损伤过程中激活Nrf2相关抗氧化损伤信号途径,其机制可能是通过下调myocardin的表达而实现的。     

CRP促进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的表达

目的探讨C反应蛋白(CRP)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(LOX-1)蛋白和mRNA的表达及相关信号转导通路的影响。方法用佛波醇脂诱导THP-1分化为巨噬细胞。用不同浓度CRP在体外干预,分别采用RT-PCR和细胞酶联免疫测定干预后巨噬细胞LOX-1抗原蛋白和mRNA的表达。同时观察当NF-κB、AP-1和MARK信号通路抑制剂存在时,CRP对LOX-1抗原和mRNA表达的影响。结果CRP促进巨噬细胞LOX-1蛋白和mRNA表达增加。NF-κB的抑制剂BAY11-7085能抑制CRP对LOX-1蛋白和mRNA表达的诱导作用。结论CRP能在转录及转录后水平诱导THP-1来源的巨噬细胞表达LOX-1,这种调节作用可能是通过NF-κB信号传导通路实现的。     

KLF6基因对THP-1细胞诱导分化的巨噬细胞凋亡的影响

目的:探讨过表达Kruppel样因子6(KLF6)基因对THP-1细胞诱导分化的巨噬细胞活力、凋亡、活性氧簇(ROS)水平及AKT信号通路的影响。方法:使用佛波酯(PMA)将人单核细胞株THP-1诱导分化为巨噬细胞,将巨噬细胞随机分为pcDNA3.1组、氧化型低密度脂蛋白(ox-LDL)组、ox-LDL+pcDNA3.1组和ox-LDL+pcDNA3.1-KLF6组,其中pcDNA3.1转染参照Lipofectamine~(TM) 2000试剂盒说明。细胞处理24 h,通过MTT实验、Annexin V-FITC/PI双标细胞凋亡试剂盒和H_2DCF-DA探针分别检测细胞活力、凋亡率和ROS水平的变化;Western blot检测Bcl-2、Bax和p-AKT的蛋白水平。结果:pcDNA3.1-KLF6转染巨噬细胞后,KLF6表达明显升高(P0.05)。ox-LDL可明显抑制巨噬细胞的活力,诱导细胞凋亡,诱导细胞ROS的产生,上调Bax表达,下调Bcl-2和p-AKT的蛋白水平;而过表达KLF6可明显减弱ox-LDL对细胞活力、凋亡、ROS水平及Bcl-2、Bax和p-AKT蛋白水平的影响(P0.05)。结论:KLF6基因可明显降低ox-LDL诱导的巨噬细胞凋亡,机制可能与降低细胞ROS水平及激活AKT信号通路有关。     

Kruppel样因子6基因对巨噬细胞中胆固醇蓄积的影响

背景:研究表明,Kruppel样因子6与巨噬细胞极化密切相关。但是,关于Kruppel样因子6在巨噬泡沫细胞形成中的作用尚不清楚。目的:观察Kruppel样因子6过表达对氧化低密度脂蛋白刺激下的小鼠巨噬细胞(RAW264.7)胆固醇蓄积及对ATP结合盒转运蛋白A1表达的影响。方法:取Raw264.7巨噬细胞株分别转染慢病毒空载体和重组载体p CDH-KLF6,作为对照组和Kruppel样因子6组,另取稳定感染慢病毒空载体的Raw264.7巨噬细胞株和稳定感染重组载体p CDH-KLF6的Raw264.7巨噬细胞株均加入50 mg/L氧化低密度脂蛋白共孵育48 h后,得到氧化低密度脂蛋白组和Kruppel样因子6+氧化低密度脂蛋白组。结果与结论:与对照组相比,氧化低密度脂蛋白组巨噬细胞内总胆固醇和胆固醇酯表达水平显著增加(P0.05)。与氧化低密度脂蛋白组巨噬细胞相比,Kruppel样因子6+氧化低密度脂蛋白组细胞内总胆固醇和胆固醇酯表达水平明显下降,胆固醇酯/总胆固醇明显降低(P0.05)。而未加入氧化低密度脂蛋白处理的2组细胞内脂质表达水平少,且对照组与Kruppel样因子6组相比,细胞内脂质表达水平差异无显著性意义。提示Kruppel样因子6可能通过促进ATP结合盒转运蛋白A1的表达,抑制氧化低密度脂蛋白诱导的RAW264.7巨噬细胞胆固醇蓄积。     

FOXF2通过Akt/mTOR信号通路影响乳腺癌肿瘤相关巨噬细胞极化

目的 探讨FOXF2表达对乳腺癌肿瘤相关巨噬细胞（TAMs）极化以及乳腺癌细胞增殖和凋亡的影响和可能机制。方法 收集30例临床乳腺癌患者的肿瘤相关巨噬细胞及配对癌旁组织巨噬细胞，qRT-PCR和Western blot检测FOXF2 mRNA和蛋白表达。转染FOXF2过表达慢病毒至小鼠腹腔巨噬细胞（PMs）,ELISA检测巨噬细胞M1/M2极化指标iNOS、TNF-α、Arg-1和IL-10表达，Western blot检测Akt/mTOR信号通路相关蛋白表达变化。将MCF-7细胞与TAMs或过表达FOXF2的TAMs共培养，CCK-8和Edu染色检测细胞增殖情况，Tunel染色检测细胞凋亡情况，Western blot检测细胞凋亡相关蛋白Bax和Bcl2表达。结果 临床乳腺癌患者的TAMs中FOXF2 mRNA和蛋白表达较配对癌旁组织巨噬细胞明显降低（P<0.05）；与对照组相比，过表达FOXF2的TAMs的M1型极化标志物（iNOS、TNF-α）表达明显升高，M2型极化标志物（Arg-1、IL-10）表达明显降低（P<0.05）;Akt/mTOR信号通路相关蛋白磷酸化水...     

SARS-CoV的S蛋白诱导呼吸道上皮细胞合成释放IP-10的信号分子机制研究

目的：研究SARS冠状病毒S蛋白诱导呼吸道上皮细胞合成释放IP-10（interferon-gamma inducible protein 10）的信号分子机制。方法：通过基因芯片检测SARS冠状病毒的S蛋白作用于人支气管上皮细胞16HBE后信号通路基因表达谱的变化；采纳RT-PCR、EMSA、Western blotting等方法进一步分析JAK-STAT通路中信号分子的磷酸化、IRF-1和IP-10基因表达的变化及其相应信号分子抑制剂对表达水平的影响。结果：S蛋白作用于人支气管上皮细胞16HBE诱导了JAK-STAT信号通路涉及的重要转录因子基因IRF-1的表达，该信号通路的转录因子STAT1在刺激后15 min发生磷酸化，2 h即可检出IP-10基因的表达， IP-10的表达可以完全被STAT1、JAK2抑制剂阻断。EMSA显示：支气管上皮细胞在S蛋白的作用下，其核蛋白能够特异性与ISRE和GAS DNA基序相结合，而不能与NF-κB的 DNA基序相结合。结论： SARS－CoV的S蛋白通过激活JAK-STAT信号转导通路诱导IP-10在宿主细胞的生成。提示病毒诱导的JAK-STAT信号通路激活在病毒感染相关的急性肺损伤发生中具有重要地位。     

M2巨噬细胞分泌的IL-10通过JAK2/STAT3信号通路调节乳腺癌细胞的增殖、侵袭与凋亡

目的探讨M2巨噬细胞分泌的IL-10通过JAK2/STAT3信号通路对乳腺癌细胞的增殖、侵袭迁移与凋亡的影响。方法THP-1细胞诱导为M2巨噬细胞,并对标志基因(CD206、ARG1、IL-6和IFN-β)进行检测;ELISA检测细胞上清液中IL-10的表达;细胞集落形成实验和EdU实验检测细胞的增殖能力;细胞侵袭与迁移实验检测细胞的侵袭与迁移能力;细胞流式术检测细胞的凋亡率和细胞周期;Western blot检测JAK2/STAT3通路相关蛋白的表达。结果 M2巨噬细胞在体外被成功诱导并进行了鉴定;与未经处理的THP-1细胞相比,M2巨噬细胞上清液中IL-10的明显增加;M2巨噬细胞分泌的IL-10可促进MDA-MB-231细胞的增殖、侵袭与迁移(均P0.001),抑制MDA-MB-231细胞的凋亡(P0.001);抑制IL-10的表达可抑制MDA-MB-231细胞的增殖、侵袭与迁移(均P0.05),促进MDA-MB-231细胞的凋亡(P0.05);IL-10可激活JAK2/STAT3信号通路,而抑制IL-10的表达可抑制JAK2/STAT3信号通路的激活。结论 M2巨噬细胞分泌的IL-10可促进乳腺癌细胞的增殖、侵袭与迁移,抑制乳腺癌细胞凋亡,其机制可能与JAK2/STAT3信号通路激活有关。     

The expression and down stream effect of lectin like-oxidized low density lipoprotein 1 (LOX-1) in hyperglycemic state

The lesions of atherosclerosis represent a series of highly specific cellular and molecular responses. Low density lipoprotein (LDL), which may be modified by oxidation, glycation, aggregation, association with proteoglycans, or incorporation into immune complexes, is a major cause of injury to the endothelium and vascular smooth muscle cells (VSMC).The major major cell types involved in atherogenesis, macrophages and VSMC, are activated by pro-inflammatory stimuli including modified LDL. Modified LDL induces inflammatory responses in macrophages, migration and proliferation of SMC, and triggers foam cell formation. Scavenger receptors, including LOX-1, play a key role in foam cell formation by mediating the uptake of modified LDL. LOX-1 expression is detected in endothelial cells of early atherosclerosis lesions of human carotid arteries. Advanced lesions showed LOX-1 expression not only in endothelial cells but also in macrophages and more frequently in VSMC, and may be involved in foam cell transformation in macrophages and VSMC. The metabolic abnormalities that characterize diabetes, particularly hyperglycemia, free fatty acids, and insulin resistance, provoke molecular mechanisms that alter the function and structure of blood vessels. These include increased oxidative stress, intracellular signal transduction disturbances, and activation of the receptor for advanced glycation end products (R-AGE). Data showed that LOX-1 expression is enhanced by proatherogenic factors relevant to human diabetes, including high glucose, oxLDL, advance glycation end products, and C-reactive protein. LOX-1 expression increased also through oxygen species (ROS), endothelin-1 (ET-1), tumor necrosis factor-alpha (TNF-alpha), shear stress, activation of protein kinase-C (PKC), angiotensin-II (ANG-II), and through inflammatory pathways.     

Sida rhomboidea.Roxb aqueous extract down-regulates in vivo expression of vascular cell adhesion molecules in atherogenic rats and inhibits in vitro macrophage differentiation and foam cell formation

The present study evaluates efficacy of Sida rhomboidea.Roxb (SR) leaves extract in ameliorating experimental atherosclerosis using in vitro and in vivo experimental models. Atherogenic (ATH) diet fed rats recorded significant increment in the serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), very LDL (VLDL), autoantibody against oxidized LDL (Ox-LDL), markers of LDL oxidation and decrement in high-density lipoprotein (HDL) along with increment in aortic TC and TG. The ex vivo LDL oxidation assay revealed an increased susceptibility of LDL isolated from ATH rats to undergo copper mediated oxidation. These set of changes were minimized by simultaneous co-supplementation of SR extract to ATH diet fed rats. Histopathology of aorta and immunolocalization studies recorded pronounced atheromatous plaque formation, vascular calcification, significant elastin derangements and higher expression of macrophage surface marker (F4/80), vascular cell adhesion molecule-1 (VCAM-1) and p-selectin in ATH rats. Whereas, ATH+SR rats depicted minimal evidence of atheromatous plaque formation, calcium deposition, distortion/defragmentation of elastin and accumulation of macrophages along with lowered expression of VCAM-1 and P-selectin compared to ATH rats. Further, monocyte to macrophage differentiation and in vitro foam cell formation were significantly attenuated in presence of SR extract. In conclusion, SR extract has the potency of controlling experimental atherosclerosis and can be used as promising herbal supplement in combating atherosclerosis.     

Difference in LDL Receptor Feedback Regulation in Macrophages and Vascular Smooth Muscle Cells: Foam Cell Transformation Under Inflammatory Stress

Macrophages and vascular smooth muscle cells (VSMCs) are the major cell types involved in foam cell formation associated with atherosclerosis. The aim of this experiment was to clarify cell-specific regulation of LDL receptor in THP-1 macrophages and human VSMCs under physiological and inflammatory conditions and its potential mechanisms. Inflammatory stress was induced by adding lipopolysaccharide (LPS) to human THP-1 macrophages and human VSMCs. Intracellular total cholesterol, free cholesterol, and cholesterol ester were measured by an enzymic assay. Oil Red O staining was used to visualize lipid droplet accumulation in cells. Total cellular RNA was isolated from cells for detecting LDL receptor, sterol regulatory element binding protein (SREBP)-2 and SREBP cleavage-activating protein (SCAP) mRNA levels using real-time quantitative polymerase chain reaction. LDL receptor, SREBP-2 and SCAP protein expression were examined by Western blotting. The translocation of SCAP from ER to Golgi was detected by confocal microscopy. LDL loading increased intracellular cholesterol level, reducing LDL receptor mRNA level in both THP-1 macrophages and VSMCs under physiological conditions. The IC50 in VSMCs was 11.25 μg/ml, which is much lower than 18.125 μg/ml in THP-1 macrophages. With the increase in concentration of LPS (0–400 ng/ml), the LDL receptor mRNA levels were upregulated in both cells, but the curve of LDL receptor mRNA in VSMCs exhibited a flatter profile than that of THP-1 macrophages. Under the treatment of 200 ng/ml of LPS, the upregulation fold of the LDL receptor mRNA in THP-1 macrophages was much higher than that of VSMCs (0.33 vs 0.04). LDL receptor blocking agent heparin decreased lipid droplets induced by LPS significantly in THP-1 macrophages and VSMCs. LDL loading reduced the SREBP2 and SCAP protein expression under physiological conditions. Exposure to LPS caused overexpression of SREBP2 and SCAP despite a high concentration of LDL in the culture medium, and increased translocation of SCAP from the ER to the Golgi in the presence of 25 μg/ml of LDL. Inflammatory stress disrupts LDL receptor negative feedback regulation induced by intracellular cholesterol in both cell types, to a greater degree in THP-1 macrophages, which could be one reason why THP-1 macrophages are more prone to become foam cells under inflammatory stress.     

DMT-1在介导低密度脂蛋白氧化中的作用

目的 通过基因芯片分析发现人单核细胞THP-1氧化LDL的过程中二价金属转运蛋白1(Divalent metal transporter 1,DMT1)的mRNA表达水平显著升高.本实验通过RT-PCR和Western Blot来验证基因芯片的结果.方法用空白,LPS,LDL分别处理THP-1细胞,应用RT-PCR和Western Blot比较在LDL和LPS处理后THP-1细胞DMT-1的表达情况.结果 RT-PCR和Western Blot结果显示,在THP-1氧化LDL的过程中DMT1的表达显著升高.LDL和LPS相比,用LDL处理的THP-1细胞的DMT1的表达增加较LPS处理的明显.结论 RT-PCR和western blot证明了基因芯片的结果,在THP-1氧化LDL的过程中DMT1的表达显著升高,为临床心血管疾病的抗氧化治疗提供新的思路.     

Sida rhomboidea.Roxb aqueous extract down-regulates in vivo expression of vascular cell adhesion molecules in atherogenic rats and inhibits in vitro macrophage differentiation and foam cell formation

The present study evaluates efficacy of Sida rhomboidea.Roxb (SR) leaves extract in ameliorating experimental atherosclerosis using in vitro and in vivo experimental models. Atherogenic (ATH) diet fed rats recorded significant increment in the serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), very LDL (VLDL), autoantibody against oxidized LDL (Ox-LDL), markers of LDL oxidation and decrement in high-density lipoprotein (HDL) along with increment in aortic TC and TG. The ex vivo LDL oxidation assay revealed an increased susceptibility of LDL isolated from ATH rats to undergo copper mediated oxidation. These set of changes were minimized by simultaneous co-supplementation of SR extract to ATH diet fed rats. Histopathology of aorta and immunolocalization studies recorded pronounced atheromatous plaque formation, vascular calcification, significant elastin derangements and higher expression of macrophage surface marker (F4/80), vascular cell adhesion molecule-1 (VCAM-1) and p-selectin in ATH rats. Whereas, ATH+SR rats depicted minimal evidence of atheromatous plaque formation, calcium deposition, distortion/defragmentation of elastin and accumulation of macrophages along with lowered expression of VCAM-1 and P-selectin compared to ATH rats. Further, monocyte to macrophage differentiation and in vitro foam cell formation were significantly attenuated in presence of SR extract. In conclusion, SR extract has the potency of controlling experimental atherosclerosis and can be used as promising herbal supplement in combating atherosclerosis.     

阿托伐他汀对巨噬细胞肝X受体表达及胆固醇外流的影响

目的:他汀类药物是目前治疗脂代谢的有效药物,通过研究阿托伐他汀对巨噬细胞的肝X受体(LXR)及其下游的一些目的基因的表达和胆固醇外流的影响,探讨他汀类药物对LXR信号系统的作用。方法:分离人外周血的单核细胞,并转化为巨噬细胞。在阿托伐他汀的作用下,观察巨噬细胞的aopA-I介导的胆固醇外流的变化和LXR以及其下游目的基因ABCA1、SREBP2、CETP、PLTP、apoE、MMP-9和MIP-1α的mRNA及蛋白LXRα、ABCA1、MMP-9和MIP-1α的表达。结果:阿托伐他汀上调LXRα、ABCA1、SREBP2、CETP、PLTP基因的表达,而下调MMP-9和MIP-1α基因的表达,同时增强aopA-I介导的胆固醇外流。结论:巨噬细胞在阿托伐他汀的作用下,胆固醇外流增强,这种效应与阿托伐他汀上调LXR及其下游的影响胆固醇代谢的目的基因有关,同时,也抑制一些炎症反应的基因的表达。提示他汀类药物的治疗作用,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。     

Expression of heme oxygenase-1 in atherosclerotic lesions.

Heme oxygenase-1 (HO-1) is a heme-degradation enzyme induced under various oxidative stress conditions. To elucidate the potential involvement of HO-1 in atherogenesis, the expression of this enzyme in atherosclerotic lesions of apolipoprotein E-deficient mice and humans were examined. Both immunostaining and in situ hybridization clearly demonstrated that the expression of HO-1 was prominent in endothelium and foam cells/macrophages of thickened intima in lesions from both humans and experimental animals. The expression of this enzyme was also detected in medial smooth muscle cells of advanced lesions. The induction of HO-1 mRNA was observed in murine peritoneal macrophages after treatment with oxidized low density lipoprotein (LDL) but not with native LDL in a dose-dependent manner. Time course study demonstrated that the induction was prominent at 3 hours, reached a maximal induction at 6 hours, and remained evident up to 24 hours after oxidized LDL treatment. The degree of induction was in concordant with the extent of oxidation in the LDL preparation. Lysophosphatidylcholine, one of the major components present in oxidized LDL, was ineffective to induce the gene expression, suggesting that other lipophilic substances derived from LDL oxidation are responsible for the induction of HO-1. These results clearly demonstrate that HO-1 is one of the stress proteins expressed in atherosclerotic lesions.     

Macrophage foam cell formation during early atherogenesis is determined by the balance between pro-oxidants and anti-oxidants in arterial cells and blood lipoproteins

Atherosclerosis is a multifactorial disease, where more than one mechanism, along more than one step, contributes to macrophage cholesterol accumulation and foam cell formation, the hallmark of early atherogenesis. Arterial macrophages take up oxidized low-density lipoproteins (Ox-LDL), leading to cellular accumulation of cholesterol and oxysterols. Atherogenic modifications of LDL include, in addition to oxidation, retention and aggregation. Intervention to inhibit LDL oxidation can affect the above additional LDL modifications. Indeed, we have demonstrated in the atherosclerotic apolipoprotein E-deficient mice that consumption of vitamin E or of flavonoids from red wine or licorice decreased LDL oxidation, LDL retention, and LDL aggregation and attenuated macrophage foam cell formation and atherosclerosis. The balance between pro-oxidants and anti-oxidants in the LDL particle (such as cholesteryl ester vs. vitamin E), as well as in arterial wall macrophages (such as NADPH oxidase vs. glutathione), determines the extent of LDL oxidation. Antioxidants can protect LDL from oxidation not only by their binding to the lipoprotein, but also following their accumulation in cells of the arterial wall. Whereas antioxidants can prevent the formation of Ox-LDL, human serum paraoxonase (PON 1), an HDL-associated esterase that hydrolyzes organophosphates, can eliminate oxidized LDL (by hydrolysis of its lipid peroxides), which is formed when antioxidant protection is not sufficient. Ox-LDL, in turn, can inactivate paraoxonase activity. Thus, the combination of antioxidants together with active paraoxonase decreases the formation of Ox-LDL and preserves PON1's ability to hydrolyze this atherogenic lipoprotein and hence, to attenuate atherosclerosis.