高密度脂蛋白抗动脉粥样硬化的新机制:调节造血干/祖细胞的功能

高密度脂蛋白(high-density lipoprotein,HDL)血浆水平与动脉粥样硬化(atherosclerosis,AS)性心血管疾病呈负相关,成为抗AS的重要靶点和热点.然而,近年来多个临床试验未能证明升高血浆HDL的水平对心血管的保护作用,使得人们开始重新审视HDL抗AS功能生物学特性的复杂性.近5年来的研究发现,HDL可通过对造血干细胞(hematopoietic stem cells,HSCs)和内皮祖细胞(endothelial progenitor cells,EPCs)功能的调节发挥抗AS的作用,本文就这一新机制进行综述,期待为HDL迄今尚不完全清楚的复杂心血管保护机制提供研究思路.     

基于高密度脂蛋白代谢与重塑的抗动脉粥样硬化研究及相关药物

动脉粥样硬化（atherosclerosis,AS）是一种主要因血脂代谢紊乱引发的慢性炎症性血管疾病,以血管内膜下巨噬细胞和血管平滑肌细胞过度蓄脂泡沫化为主要病理特征。高密度脂蛋白（high-density lipoprotein,HDL）通过胆固醇逆向转运（reverse cholesterol transport,RCT）将外周细胞中的胆固醇运输到肝脏然后经胆汁排出体外,从而改善血脂水平和细胞的过度蓄脂,被认为是HDL抗AS的基础。然而,大量流行病学证据表明,虽然血浆高密度脂蛋白胆固醇（high-density lipoprotein cholesterol,HDL-C）水平与心血管风险呈负相关,但仅仅提高HDL-C水平的治疗策略不一定能增加临床效益。因此,学术界认识到HDL水平不足以反映其RCT能力,而更多取决于HDL功能。本文综述了参与调节HDL功能的各种分子对HDL代谢与重塑过程的影响,以及针对上述过程的相关药物研究进展,为更全面评价HDL的抗AS作用提供理论参考。     

高密度脂蛋白的水平与功能

传统观念在发生变化,胆固醇长期被认为是损伤心血管系统的重要危害因素,需要控制摄入,但最近这个观念被修改。过往认为高密度脂蛋白(high density lipoprotein,HDL)可保护心血管,但通过升高血浆高密度脂蛋白胆固醇(HDL-C)水平来降低心血管事件的发生率并没有得到理想的效果。遗传学研究发现影响HDL-C水平的基因座的单核苷酸多态性与冠心病的风险无明显相关性。与HDL功能和活性密切相关分子的遗传变异对心血管疾病的意义更大,并且多种表观遗传分子参与HDL功能的调控,与HDL-C水平相比,HDL的功能可能更关键。冠心病、糖尿病、慢性肾病、类风湿性关节炎和心脏外科手术等疾病状态下HDL中的多种成分发生改变,其胆固醇逆向转运、抗炎、抗氧化、内皮保护等正常功能受到不同程度的损害,导致其正常心血管保护作用丧失,甚至损害心血管。因此,探究疾病状态下HDL对心血管损伤的具体机制有利于心血管疾病的防治。     

HDL转运的miR-223调控内皮细胞ICAM-1的表达

<正>众所周知,血浆中高密度脂蛋白HDL的浓度与心血管疾病发生的风险负相关。对HDL心血管保护功能研究最多的是它在胆固醇逆向转运中的作用。此外,HDL还有抑制多种细胞免疫炎症的作用,比如HDL可以抑制内皮细胞的激活和粘附分子的表达。HDL具有异质性,由若干结构和功能各异的颗粒亚群组成,成分复杂,包括脂蛋白、磷脂、小RNA(miR)等。这导致目前关于HDL心血管保护作用的机制了解不是很多。本文作者研究了HDL的各个组分对于内皮细胞基因表达谱和miR     

异常修饰后高密度脂蛋白组分的改变对其功能的影响

高密度脂蛋白(high-density lipoprotein,HDL)是由载脂蛋白、脂质和多种功能蛋白所组成的结构复杂的多功能复合物。正常人血浆中的HDL主要通过胆固醇逆向转运(reverse cholesterol transport,RCT)发挥抗动脉粥样硬化(atherosclerosis,AS)作用,除此之外,HDL还有修复内皮细胞、抗炎、抗氧化和抗凋亡等作用。在全身炎症或代谢性疾病中,HDL组分被异常修饰,使其成分和功能发生改变,进而转变为功能失调HDL。功能失调HDL在成分和功能上均发生了改变:成分上载脂蛋白A-Ⅰ(apolipoprotein A-Ⅰ,apo A-Ⅰ)、对氧磷酶(paraoxonase,PON)和血小板活化因子乙酰水解酶(platelet activating factor acetylhydrolase,PAF-AH)等减少,而血清淀粉样蛋白A(serum amyloid A,SAA)、甘油三酯(triglyceride,TG)和氧化脂质等增加;功能上不仅失去了抗AS、抗炎、抗氧化等作用,反而具有促炎作用,可见盲目升高血浆HDL-C的含量并不一定能达到预期效果。因此了解异常修饰后HDL成分和功能的改变对深入了解功能失调HDL的致病机制具有重要的指导意义。     

高密度脂蛋白组成成分对心血管疾病的影响北大核心CSCD

高密度脂蛋白(HDL)是由脂质和蛋白质及其所携带的调节因子组成的复合体,具有抗动脉粥样硬化(AS)和抗炎症反应等多种功能。近年来,HDL组成成分对AS发病过程的调节机制受到广泛关注和研究。在AS发病过程中,HDL中的对氧磷酶(PON)可抑制低密度脂蛋白的氧化。HDL中载脂蛋白A-I(Apo A-I)的结构和功能改变,载脂蛋白A-II(Apo A-II)对apo A-I空间构象的调节,血清淀粉样蛋白A(SAA)与apo A-I的拮抗作用,载脂蛋白M(Apo M)和HDL-miR-223表达减少,以及HDL-miR-92a和HDL-miR-24表达增多均会削弱HDL的抗AS能力。本文主要综述HDL组成成分对心血管疾病(CVD)发生发展的影响,以期为HDL在AS相关疾病中的作用提供新思路,为CVD的治疗提供新方法。     

高密度脂蛋白组成成分对心血管疾病的影响

高密度脂蛋白(HDL)是由脂质和蛋白质及其所携带的调节因子组成的复合体,具有抗动脉粥样硬化(AS)和抗炎症反应等多种功能。近年来,HDL组成成分对AS发病过程的调节机制受到广泛关注和研究。在AS发病过程中,HDL中的对氧磷酶(PON)可抑制低密度脂蛋白的氧化。HDL中载脂蛋白A-I(Apo A-I)的结构和功能改变,载脂蛋白A-II(Apo A-II)对apo A-I空间构象的调节,血清淀粉样蛋白A(SAA)与apo A-I的拮抗作用,载脂蛋白M(Apo M)和HDL-miR-223表达减少,以及HDL-miR-92a和HDL-miR-24表达增多均会削弱HDL的抗AS能力。本文主要综述HDL组成成分对心血管疾病(CVD)发生发展的影响,以期为HDL在AS相关疾病中的作用提供新思路,为CVD的治疗提供新方法。     

失功能性HDL研究进展

高密度脂蛋白胆固醇(HDL-C)水平与动脉粥样硬化呈负相关,HDL被认为具有抗动脉粥样硬化(AS)作用。但急性期反应、慢性炎症及一些代谢性疾病中,HDL组成成分变化及其功能基团的病理性修饰可造成HDL失功能化,失功能性HDL中蛋白质、脂类、酶类发生特征性改变,具有促动脉粥样硬化作用。随着研究深入,人们逐步认识到HDL的功能比HDL-C水平更重要。microRNAs与失功能性HDL具有相关性,还参与心血管系统及代谢系统疾病的发生发展,HDL受到包括microRNAs在内的一系列信号分子调控。本文主要综述失功能性HDL的结构、特征以及与动脉粥样硬化、microRNAs之间的关系,为动脉粥样硬化防治提供新的思路和方法。     

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.     

apoA-Ⅰ的α螺旋在胆固醇流出中的作用

血浆载脂蛋白A-Ⅰ(apoA-Ⅰ)的水平与动脉粥样硬化(atherosclerosis,AS)性心血管疾病的风险呈负相关.ApoA-Ⅰ经载脂形成高密度脂蛋白(HDL),HDL通过促进胆固醇逆向转运(RCT),使细胞内的多余胆固醇流出.α螺旋是apoA-Ⅰ载脂的主要结构,在apoA-Ⅰ参与的胆固醇流出中具有重要作用.模拟α螺旋建立的apoA-Ⅰ模拟肽能通过不同方式发挥抗AS的作用.本文就α螺旋在胆固醇流出中的作用作一综述,以便进一步探索apoA-Ⅰ的结构对胆固醇流出的影响,为以apoA-Ⅰ为靶点防治AS提供理论基础.     

HDL revisited: new opportunities for managing dyslipoproteinaemia and cardiovascular disease

Low concentrations of high-density lipoprotein (HDL) cholesterol constitute a risk factor for coronary heart disease (CHD). There is increasing evidence that increasing HDL-cholesterol levels reduces cardiovascular risk. The phenotype of low HDL cholesterol with or without elevated triglycerides is common and it is characteristic of patients with central obesity, insulin resistance, hypertension and type 2 diabetes mellitus; conditions associated with increased cardiovascular risk and are part of the rubric of the metabolic syndrome. Epidemiological, experimental and clinical trial evidence suggests that there is a good rationale for raising HDL-cholesterol in these and other high-risk patients. The protective effect of HDL-cholesterol against atherosclerosis and cardiovascular disease is mediated by both enhanced reverse cholesterol transport (RCT) and by direct anti-atherosclerotic mechanisms. Recent studies have elucidated mechanisms whereby HDL acts to reduce cardiovascular risk, supporting the rationale for targeting of HDL with lipid-modifying therapy. Ongoing investigation of mechanisms by which HDL acts to reduce the risk of atherosclerosis will provide opportunities for the development of new therapeutic strategies to decrease the risk of atherosclerosis.     

The HDL receptor SR-BI: a new therapeutic target for atherosclerosis?

Although high-density lipoprotein (HDL) metabolism is a crucial process for cholesterol homeostasis and coronary heart disease, therapeutic approaches for selective modification of plasma HDL levels are not currently available. The discovery of well-defined cell-surface HDL receptors should provide new avenues for treatment of atherosclerotic cardiovascular disease. In fact, SR-BI, a recently identified receptor for selective HDL cholesterol uptake, is relevant for physiological processes (for example, HDL metabolism, steroidogenesis and biliary cholesterol secretion) and pathophysiological conditions (for example, atherosclerosis) in animal models. If SR-BI has similar activities in humans, it might represent a new therapeutic target for atherosclerosis.     

Molecular basis of cholesterol homeostasis: lessons from Tangier disease and ABCA1

High-density lipoproteins (HDLs) play a role in transporting cholesterol from peripheral tissues to the liver for elimination from the body. Two hallmarks of cardiovascular disease are the presence of sterol-laden macrophages in the artery wall and reduced plasma HDL levels. A cell-membrane protein called ABCA1 mediates the secretion of excess cholesterol from cells into the HDL metabolic pathway. Mutations in ABCA1 cause Tangier disease, a severe HDL deficiency syndrome characterized by accumulation of cholesterol in tissue macrophages and prevalent atherosclerosis. Because of its ability to deplete macrophages of cholesterol and to raise plasma HDL levels, ABCA1 has become a promising therapeutic target for preventing cardiovascular disease.     

The HDL hypothesis: does high-density lipoprotein protect from atherosclerosis?

There is unequivocal evidence of an inverse association between plasma high-density lipoprotein (HDL) cholesterol concentrations and the risk of cardiovascular disease, a finding that has led to the hypothesis that HDL protects from atherosclerosis. This review details the experimental evidence for this “HDL hypothesis”. In vitro studies suggest that HDL has a wide range of anti-atherogenic properties but validation of these functions in humans is absent to date. A significant number of animal studies and clinical trials support an atheroprotective role for HDL; however, most of these findings were obtained in the context of marked changes in other plasma lipids. Finally, genetic studies in humans have not provided convincing evidence that HDL genes modulate cardiovascular risk. Thus, despite a wealth of information on this intriguing lipoprotein, future research remains essential to prove the HDL hypothesis correct.     

Lecithin:cholesterol acyltransferase: old friend or foe in atherosclerosis?

Lecithin:cholesterol acyltransferase (LCAT) is a key enzyme that catalyzes the esterification of free cholesterol in plasma lipoproteins and plays a critical role in high-density lipoprotein (HDL) metabolism. Deficiency leads to accumulation of nascent preβ-HDL due to impaired maturation of HDL particles, whereas enhanced expression is associated with the formation of large, apoE-rich HDL(1) particles. In addition to its function in HDL metabolism, LCAT was believed to be an important driving force behind macrophage reverse cholesterol transport (RCT) and, therefore, has been a subject of great interest in cardiovascular research since its discovery in 1962. Although half a century has passed, the importance of LCAT for atheroprotection is still under intense debate. This review provides a comprehensive overview of the insights that have been gained in the past 50 years on the biochemistry of LCAT, the role of LCAT in lipoprotein metabolism and the pathogenesis of atherosclerosis in animal models, and its impact on cardiovascular disease in humans.     

Interrelations between sex hormone-binding globulin (SHBG), plasma lipoproteins and cardiovascular risk

The incidence of coronary artery disease is significantly higher in men than in women, at least until menopause. This gender difference could be explained by the action of sex steroids on the lipoprotein profile. In prepubertal children, high-density lipoprotein (HDL) cholesterol and triglyceride levels are similar between sexes, while adult men have generally lower HDL cholesterol and higher triglyceride levels than premenopausal adult women. Most cross-sectional studies have reported that sex hormone binding globulin (SHBG) and testosterone levels correlate positively with HDL cholesterol levels between sexes. Thus SHBG by modulating the balance in the biodisposal of testosterone and estradiol, might have a profound effect on the risk of cardiovascular disease. However, adjustment for body weight and body fat distribution weakens the association between SHBG, testosterone and HDL cholesterol. The negative correlation of fasting insulin with SHBG and HDL cholesterol levels in both sexes, and some evidence that insulin is an inhibitor of SHBG production in vitro, has suggested that hyperinsulinism might negatively regulate SHBG and HDL levels. It remains to be determined whether the inverse relationship between SHBG and insulin levels is coincidental or has a causal effect on the increase of atherosclerosis. Decreased SHBG has been shown to be predictive of the incidence of non-insulin-dependent diabetes mellitus in women but not in men, and of subsequent development of cardiovascular disease and overall mortality in postmenopausal women. SHBG is an index of androgenism in women and of insulin-resistance in both sexes, and might be useful in epidemiological studies of cardiovascular risk. However, in men, SHBG is not predictive of the occurrence of cardiovascular disease. Whether SHBG might have an intrinsic protective effect on the arterial wall through SHBG-receptors is still highly speculative.     

High-density lipoproteins as therapeutic targets

PURPOSE OF REVIEW: The concentration of cholesterol in HDL is an inverse predictor of future cardiovascular disease, with evidence mounting that therapies that increase HDL concentration are antiatherogenic. The best known antiatherogenic function of HDL particles relates to their ability to promote the efflux of cholesterol from cells. However, they also have antioxidant, antiinflammatory and antithrombotic properties. RECENT FINDINGS: The past year has seen the publication of several papers that highlight a potential major protective role of HDL in states of acute inflammation. Papers showing extremely promising results using novel inhibitors of cholesteryl ester transfer protein as HDL-raising agents have also appeared. Finally, the discovery that ATP-binding cassette transporter G1 (ABCG1) transports cell cholesterol to large HDL particles in the extracellular space has largely reconciled apparent inconsistencies between basic research indicating that small, pre-beta-migrating HDL particles are the antiatherogenic components of HDL and epidemiological research that implicates larger HDL particles as the protective fraction. SUMMARY: The finding that ABCG1 promotes the efflux of cholesterol from cells to large HDL particles also provides powerful circumstantial evidence that cholesteryl ester transfer protein inhibition (which increases HDL size) may enhance, rather than reduce, cholesterol efflux, and thus inhibit the development of atherosclerosis.     

ABCA1. The gatekeeper for eliminating excess tissue cholesterol

It is widely believed that HDL functions to transport cholesterol from peripheral cells to the liver by reverse cholesterol transport, a pathway that may protect against atherosclerosis by clearing excess cholesterol from arterial cells. A cellular ATP-binding cassette transporter (ABC) called ABCA1 mediates the first step of reverse cholesterol transport: the transfer of cellular cholesterol and phospholipids to lipid-poor apolipoproteins. Mutations in ABCA1 cause Tangier disease (TD), a severe HDL deficiency syndrome characterized by accumulation of cholesterol in tissue macrophages and prevalent atherosclerosis. Studies of TD heterozygotes revealed that ABCA1 activity is a major determinant of plasma HDL levels and susceptibility to CVD. Drugs that induce ABCA1 in mice increase clearance of cholesterol from tissues and inhibit intestinal absorption of dietary cholesterol. Multiple factors related to lipid metabolism and other processes modulate expression and tissue distribution of ABCA1.Therefore, as the primary gatekeeper for eliminating tissue cholesterol, ABCA1 has a major impact on cellular and whole body cholesterol metabolism and is likely to play an important role in protecting against cardiovascular disease.     

ATP binding cassette transporter A1 - key roles in cellular lipid transport and atherosclerosis

ATP-binding cassette transporter A1 (ABCA1) was recently recognized as the mutant molecule responsible for Tangier disease with low HDL levels, accumulation of cholesteryl esters in tissues, and increased risk of cardiovascular disease. Extensive studies for the past 2 years have recognized the critical role of ABCA1 in cholesterol and phospholipid trafficking. Since the removal of cholesterol from tissues is a key step in the prevention of atherosclerosis, significant attention has been focused on this molecule. Natural ABCA1 mutations in Tangier disease (TD) patients and WHAM chickens together with induced mutation in ABCA1 knock-out mice unequivocally established the important role of ABCA1 in maintaining circulating HDL levels and promoting cholesterol efflux from the arterial wall. Mice lacking ABCA1 showed similar phenotypes observed in Tangier disease patients with low levels of HDL. Further understanding of the roles of ABCA1 in lipid transport and atherosclerosis became clear from studies with ABCA1 transgenic mice. These mice showed enhanced cholesterol efflux from macrophages and reduced atherosclerotic lesion formation. The promoter of the ABCA1 gene has been mapped to a large extent, with the exception of cAMP response element. The present review summarizes recent developments on the role of ABCA1 in cholesterol efflux and prevention of atherosclerosis. Given the antiatherogenic properties of ABCA1, this molecule can serve as an appropriate target for developing drugs to treat individuals with low levels of HDL.     

Athero-protective Effects of High Density Lipoproteins (HDL): An ODE Model of the Early Stages of Atherosclerosis

We present an ODE model which we use to investigate how High Density Lipoproteins (HDL) reduce the inflammatory response in atherosclerosis. HDL causes atherosclerotic plaque stabilisation and regression, and is an important potential marker and prevention target for cardiovascular disease. HDL enables cholesterol efflux from the arterial wall, macrophage and foam cell emigration, and has other athero-protective effects. Our basic inflammatory model is augmented to include several different ways that HDL can act in early atherosclerosis. In each case, the action of HDL is represented via a parameter in the model. The long-term model behaviour is investigated through phase plane analysis and simulations. Our results indicate that only HDL-enabled cholesterol efflux can stabilise the internalised lipid content in the lesion so that it does not continue to grow, but this does not reduce macrophage numbers which is required to stabilise the lesion or prevent rupture. HDL-enabled macrophage emigration guarantees lesion stabilisation by maintaining stable macrophage content.