卵磷脂胆固醇酰基转移酶基因608C/T多态性与脑出血的关联研究

卵磷脂胆固醇酰基转移酶(LCAT)是一种在高密度脂蛋白(HDL)代谢和动脉粥样硬化(AS)发展中的关键酶[1].近年来,国内外学者们从多层次、多角度深入探讨LCAT、的功能,研究显示,LCAT为AS的易感基因之一[2],其多态现象可能与冠心病的发生有关[3-4].AS在卒中发生中也起重要的作用,我们在前期研究发现,LCAT 608C/T多态性可能为中国汉族人群脑梗死的易感因素[5].本研究试通过对LCAT 608C/T多态性与脑出血的关联研究,进一步探讨LCAT多态性与卒中的关系.     

血清胆固醇水平与死亡率的关系

虽然公认冠心病患者血清胆固醇水平升高,但是也有不少学者报道未能见到血清胆固醇与冠心病发病率的相关关系。鉴于冠心病死亡率在心血管病死亡和总死亡率中均占较大比例,因此,我们对血清胆固醇水平的变化与心血管病死亡率和总死亡率的关系,进行了历时30年的追踪观察,从动态过程中观察胆固醇与冠心病之间的关系。     

增龄对大鼠血清卵磷脂胆固醇酰基转移酶活性的影响

本文采用比色法对不同月龄大鼠血清卵磷脂胆固醇酰基转移酶(LCAT)活性进行了测定。结果表明,20月龄组LCAT活性明显低于4月龄组(P<0.05),表明血清LCAT活性在老年时降低。LCAT活性下降可导致胆固醇酯化和HDL_3向HDL_2转化障碍,影响胆固醇的逆向转运,促进动脉粥样硬化的形成。     

血清卵磷脂胆固醇酰基转移酶活性与冠心病的关系

目的探讨血清卵磷脂胆固醇酰基转移酶活性(LCAT)与冠心病(CAD)的关系。方法本研究为病例对照研究。纳入2014年11月至2015年8月在北京医院行冠脉造影的425例患者,按冠状动脉造影结果分为CAD组(341例)和非CAD对照组(84例),应用高效液相色谱法测定血清LCAT活性,分析LCAT活性与CAD及其他危险因素的关系。结果 CAD组中LCAT活性显著高于非CAD组[(37. 3±9. 7)n Kat/L比(34. 8±8. 8)n Kat/L,P=0. 03],两组的高密度脂蛋白胆固醇、Apo AI和随机血糖等均有显著差异(均为P<0. 05)。Spearman相关性分析显示,LCAT活性与体质指数(r=0. 09)、TG(r=0. 30)、Apo B(r=0. 22)和随机血糖(r=0. 09)呈正相关;与HDL-C(r=-0. 26)呈负相关(均为P<0. 05)。单因素logistic回归分析结果显示,LCAT活性升高是CAD危险因素(OR=3. 11,95%CI:1. 40～6. 91,P=0. 005),在校正年龄、性别、HDL-C、Apo AI、随机血糖等危险因素后,多因素logistic回归分析发现LCAT的活性升高仍是CAD危险因素(OR=3. 28,95%CI:1. 27～8. 50,P=0. 014)。结论 LCAT活性升高与冠心病独立相关,但仍需更多研究证实。     

表没食子酸儿茶素没食子酸酯对高脂饮食引起的高血脂大鼠的保护作用研究

目的探讨表没食子儿茶素没食子酸酯(EGCG)的降血脂作用及其机制。方法将50只Wistar大鼠随机分成5组,对照组、高脂饲料组(模型组)及EGCG小、中、大剂量+高脂饲料组。测定大鼠血清三酰甘油(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、清卵磷脂胆固醇脂酰基转移酶(LCAT)、心肌脂蛋白脂酶(LPL)、肝脂酶(HL)活性以及体外对大鼠血管反应性。结果 EGCG可明显降低喂以高脂饲料小鼠血清TC、TG及LDL-C水平,提高HDL-C含量,且作用与EGCG剂量呈正相关。EGCG在不同程度上可升高血清LCAT、LPL和HL的活性。结论 EGCG有显著降血脂效应,其机制一方面可能是促进了脂蛋白之间的代谢与转化,另外可能是因为抑制了肠道胆固醇的吸收,减少了肝脏胆固醇的合成,促进了血清和肝脏三酰甘油的分解。     

卵磷脂胆固醇酰基转移酶基因多态性与脑出血的关系

目的探讨卵磷脂胆固醇酰基转移酶(LCAT)基因511C/T多态性与汉族人群脑出血的关系。方法选择2012年6月至2013年10月该院收治的原发性脑出血患者102例,健康对照120例。采用聚合酶链式反应(PCR)、单链构象多态性(SSCP)和DNA测序法检测LCAT 511C/T基因多态性。采用氧化酶法检测受试者血脂水平。结果脑出血组CT基因型频率为6.87%,对照组为1.67%,脑出血组T等位基因频率为3.43%,对照组为0.83%,组间差异均无统计学意义(P>0.05)。511CC组总胆固醇(TC)水平明显低于511CT组,而高密度脂蛋白胆固醇(HDL-C)水平升高(t=2.524,P=0.013;t=1.871,P=0.049)。在脑出血组中,511CC组HDL-C水平明显高于511CT亚组(t=1.954,P=0.047)。结论 LCAT基因511C/T多态性与脑出血无关,而T等位基因与HDL-C代谢有关。     

卵磷脂胆固醇酰基转移酶基因多态性与动脉粥样硬化性脑梗死的研究

目的探讨卵磷脂胆固醇酰基转移酶(LCAT)基因511C/T多态性在中国汉族人群中的分布及其与动脉粥样硬化性脑梗死(ACI)的关系。方法应用PCR、单链构象多态性技术和DNA测序法检测ACI患者150例(ACI组)和健康体检者122例(对照组)LCAT511C/T多态性。根据基因多态性将ACI组分为2个亚组,511CC组(135例)和511CT组(15例)。结果LCAT第四外显子511位点存在多态现象,此多态位点C/T在ACI组和对照组均符合Hardy-Weinberg平衡定律。ACI组CT基因型频率、T等位基因频率均显著高于对照组(P<0.01)。511CC组HDL-C水平高于511CT组(P<0.05)。结论LCAT第四外显子511C/T多态性可能为中国汉族人群ACI易感因素,T等位基因可能与HDL-C代谢有关。     

高脂血症家族遗传因素与心血管病危险因素的聚集性研究

目的探讨高脂血症家族遗传因素与心血管病危险因素个体聚集性的关系。方法采用遗传流行病学研究方法,分析高脂血症先证者一级亲属与二级亲属心血管病危险因素的个体聚集性。其中,家族性混合型高脂血症家系15个（共93人）,家族性高胆固醇血症家系11个（共94人）。结果超重、高收缩压、高舒张压、高apoB血症、高血糖、低水平高密度脂蛋白胆固醇,这6种高危因素中,心血管病危险因素的个体聚集性随着先证者亲属亲缘系数的下降而下降（P<0.01）。结论高脂血症家族遗传因素对心血管病危险因素的聚集起着重要作用。     

高脂血症家族遗传因素与心血管病危险因素的聚集性研究

目的 探讨高脂血症家族遗传因素与心血管病危险因素个体聚集性的关系。方法 采用遗传流行病学研究方法,分析高脂血症先证者一级亲属与二级亲属心血管病危险因素的个体聚集性。其中,家族性混合型高脂血症家系15个（共93人）,家族性高胆固醇血症家系11个（共94人）。结果 超重、高收缩压、高舒张压、高apoB血症、高血糖、低水平高密度脂蛋白胆固醇,这6种高危因素中,心血管病危险因素的个体聚集性随着先证者亲属亲缘系数的下降而下降（P＜0．01）。结论 高脂血症家族遗传因素对心血管病危险因素的聚集起着重要作用。     

中国11省市队列人群危险因素与不同类型心血管病发病危险的比较

目的描述在中国35—64岁人群中,不同类型心血管病（包括急性冠心病事件、急性缺血性脑卒中和出血性脑卒中事件）发病的特点。比较传统心血管病危险因素与冠心病和脑卒中（急性缺血性脑卒中和出血性脑卒中事件）发病危险的关系。方法以中国多省市前瞻性队列研究的数据为基础,该队列由1992年建立的11省市35～64岁27249人和1996年到1999年又加入的3129人所组成,共30378人。本研究基线危险因素水平和1992--2003年期间发生的心血管病（包括冠心病和脑卒中）事件的关系进行分析。结果（1）急性冠心病事件、急性缺血性脑卒中事件和急性出血性脑卒中事件的累积人年发病率分别为114／100000、209／100000和73／100000。（2）随访期间发生心血管病的亚组人群基线时有84％～89％的人伴有1个或1个以上的心血管病危险因素,高于无心血管病的亚组人群（64．7％,P〈0．01）。（3）危险因素对不同类型心血管病发病的影响及作用强度有所差别：对冠心病发病危险的影响因素根据强度依次为高血压、吸烟、高胆固醇血症和低高密度脂蛋白胆固醇血症;对缺血性脑卒中发病危险的影响因素依次为高血压、糖尿病、低高密度脂蛋白胆固醇血症、吸烟和肥胖;对出血性脑卒中发病危险的独立影响因素只有高血压。结论在心血管病的主要危险因素中,不同的危险因素对不同类型的心血管病发病危险的作用存在差别。我国人群不同危险因素的变化趋势将影响不同类型心血管。     

Lecithin Cholesterol Acyltransferase: An Anti- or Pro-atherogenic Factor?

Lecithin cholesterol acyl transferase (LCAT) is a plasma enzyme that esterifies cholesterol and raises high-density lipoprotein cholesterol, but its role in atherosclerosis is not clearly established. Studies of various animal models have yielded conflicting results, but studies done in rabbits and non-human primates, which more closely simulate human lipoprotein metabolism, indicate that LCAT is likely atheroprotective. Although suggestive, there are also no biomarker studies that mechanistically link LCAT with cardiovascular disease. Imaging studies of patients with LCAT deficiency have also not yielded a clear answer to the role of LCAT in atherosclerosis. Recombinant LCAT, however, is currently being developed as a therapeutic product for enzyme replacement therapy of patients with genetic disorders of LCAT for the prevention and/or treatment of renal disease, but it may also have value for the treatment of acute coronary syndrome.     

High plasma lecithin:cholesterol acyltransferase activity does not predict low incidence of cardiovascular events: Possible attenuation of cardioprotection associated with high HDL cholesterol

The cholesterol esterifying enzyme, lecithin:cholesterol acyltransferase (LCAT), is crucial in high density lipoprotein (HDL) metabolism. The role of LCAT activity on incident cardiovascular disease (CVD) is unknown. We determined the association of incident CVD with plasma LCAT activity, and evaluated whether LCAT may modify the cardioprotective effect of higher HDL cholesterol. In a community-based prospective nested case-control study (PREVEND cohort), an exogenous substrate assay was used to measure plasma LCAT activity in 116 men who developed CVD (cases) and in 111 male controls. Plasma LCAT activity was 5% higher in cases (P = 0.027) in association with higher total cholesterol, non-HDL cholesterol and triglycerides. Age-adjusted incident CVD was increased with higher LCAT activity (continuous variable: hazard ratio (HR) 1.23; 95% CI 1.01–1.49, P = 0.037; upper quartile vs. lowest 3 quartiles: HR 1.60; 95% CI 1.07–2.39, P = 0.021). This relationship was not significant after adjustment for lipids. Compared to subjects with HDL cholesterol above the median and lower LCAT activity (lowest 3 quartiles) the age-adjusted cardiovascular risk was elevated in subjects with similarly higher HDL cholesterol and higher LCAT activity (HR 2.38; 95% CI 1.27–4.49, P = 0.007), lower HDL cholesterol and lower LCAT activity (HR 2.58; 95% CI 1.64–4.49, P < 0.001) and lower HDL cholesterol and higher LCAT activity (HR 2.76; 95% CI 1.58–4.83, P < 0.001). These HRs were unchanged after non-HDL cholesterol and triglyceride adjustment. In conclusion, high plasma LCAT activity does not predict reduced CVD risk, and may attenuate cardioprotection associated with higher HDL cholesterol.     

Methionine oxidation impairs reverse cholesterol transport by apolipoprotein A-I

HDL protects against vascular disease by accepting free cholesterol from macrophage foam cells in the artery wall. This pathway is critically dependent on lecithin:cholesterol acyltransferase (LCAT), which rapidly converts cholesterol to cholesteryl ester. The physiological activator of LCAT is apolipoprotein A-I (apoA-I), the major HDL protein. However, cholesterol removal is compromised if apoA-I is exposed to reactive intermediates. In humans with established cardiovascular disease, myeloperoxidase (MPO) oxidizes HDL, and oxidation by MPO impairs apoA-I's ability to activate LCAT in vitro. Because a single methionine residue in apoA-I, Met-148, resides near the center of the protein's LCAT activation domain, we determined whether its oxidation by MPO could account for the loss of LCAT activity. Mass spectrometric analysis demonstrated that oxidation of Met-148 to methionine sulfoxide associated quantitatively with loss of LCAT activity in both discoidal HDL and HDL₃, the enzyme's physiological substrates. Reversing oxidation with methionine sulfoxide reductase restored HDL's ability to activate LCAT. Discoidal HDL prepared with apoA-I containing a Met-148→Leu mutation was significantly resistant to inactivation by MPO. Based on structural data in the literature, we propose that oxidation of Met-148 disrupts apoA-I's central loop, which overlaps the LCAT activation domain. These observations implicate oxidation of a single Met in apoA-I in impaired LCAT activation, a critical early step in reverse cholesterol transport.     

Current Status of Familial LCAT Deficiency in Japan

Lecithin cholesterol acyltransferase (LCAT) is a lipid-modification enzyme that catalyzes the transfer of the acyl chain from the second position of lecithin to the hydroxyl group of cholesterol (FC) on plasma lipoproteins to form cholesteryl acylester and lysolecithin. Familial LCAT deficiency is an intractable autosomal recessive disorder caused by inherited dysfunction of the LCAT enzyme. The disease appears in two different phenotypes depending on the position of the gene mutation: familial LCAT deficiency (FLD, OMIM 245900) that lacks esterification activity on both HDL and ApoB-containing lipoproteins, and fish-eye disease (FED, OMIM 136120) that lacks activity only on HDL. Impaired metabolism of cholesterol and phospholipids due to LCAT dysfunction results in abnormal concentrations, composition and morphology of plasma lipoproteins and further causes ectopic lipid accumulation and/or abnormal lipid composition in certain tissues/cells, and serious dysfunction and complications in certain organs. Marked reduction of plasma HDL-cholesterol (HDL-C) and corneal opacity are common clinical manifestations of FLD and FED. FLD is also accompanied by anemia, proteinuria and progressive renal failure that eventually requires hemodialysis. Replacement therapy with the LCAT enzyme should prevent progression of serious complications, particularly renal dysfunction and corneal opacity. A clinical research project aiming at gene/cell therapy is currently underway.     

High-density lipoprotein metabolism: Molecular targets for new therapies for atherosclerosis

New therapeutic approaches to the prevention and treatment of atherosclerotic cardiovascular disease (ASCVD) are needed. Plasma levels of high-density lipoprotein (HDL) cholesterol are inversely associated with risk of ASCVD. Genes involved in the metabolism of HDL represent potential targets for the development of such therapies. Because HDL metabolism is a dynamic process, the effect of a specific HDL-oriented intervention on atherosclerosis cannot necessarily be predicted by its effect on the plasma HDL cholesterol level. Based on available data in animal models, some gene products are candidates for pharmacologic upregulation, infusion, or overexpression, including apolipoprotein (apo)A-I, apoE, apoA-IV, lipoprotein lipase (LPL), ATP-binding cassette protein 1 (ABC1), lecithin cholesterol acyltransferase (LCAT), and scavenger receptor B-I (SR-BI). In contrast, some gene products are potential candidates for inhibition, including apoA-II, cholesteryl ester transfer protein (CETP), and hepatic lipase. The next decade will witness the transition from preclinical studies to clinical trials of a variety of new therapies targeted toward HDL metabolism and atherosclerosis.     

Genetic lecithin:cholesterol acyltransferase deficiency and cardiovascular disease

The lecithin:cholesterol acyltransferase (LCAT) enzyme is responsible for the synthesis of cholesteryl esters in human plasma and plays a critical role in high density lipoprotein (HDL) metabolism. Genetic LCAT deficiency is a rare metabolic disorder characterized by low HDL cholesterol levels. This paper reviews the genetic and biochemical features of LCAT deficiency, highlighting the absence of enhanced preclinical atherosclerosis in carriers, despite the remarkably low HDL cholesterol.     

AAV8-Mediated Long-Term Expression of Human LCAT Significantly Improves Lipid Profiles in hCETP;Ldlr+/− Mice

Lecithin:cholesterol acyltransferase (LCAT) is the key circulating enzyme responsible for high-density lipoprotein (HDL) cholesterol esterification, HDL maturation, and potentially reverse cholesterol transport. To further explore LCAT's mechanism of action on lipoprotein metabolism, we employed adeno-associated viral vector (AAV) serotype 8 to achieve long-term (32-week) high level expression of human LCAT in hCETP;Ldlr(+/-) mice, and characterized the lipid profiles in detail. The mice had a marked increase in HDL cholesterol, HDL particle size, and significant reduction in low-density lipoprotein (LDL) cholesterol, plasma triglycerides, and plasma apoB. Plasma LCAT activity significantly increased with humanized substrate specificity. HDL cholesteryl esters increased in a fashion that fits human LCAT specificity. HDL phosphatidylcholines trended toward decrease, with no change observed for HDL lysophosphatidylcholines. Triglycerides reduction appeared to reside in all lipoprotein particles (very low-density lipoprotein (VLDL), LDL, and HDL), with HDL triglycerides composition highly reflective of VLDL, suggesting that changes in HDL triglycerides were primarily driven by the altered triglycerides metabolism in VLDL. In summary, in this human-like model for lipoprotein metabolism, AAV8-mediated overexpression of human LCAT resulted in profound changes in plasma lipid profiles. Detailed lipid analyses in the lipoprotein particles suggest that LCAT's beneficial effect on lipid metabolism includes not only enhanced HDL cholesterol esterification but also improved metabolism of apoB-containing particles and triglycerides. Our findings thus shed new light on LCAT's mechanism of action and lend support to its therapeutic potential in treating dyslipidemia.     

The Arg123-Tyr166 central domain of human ApoAI is critical for lecithin:cholesterol acyltransferase-induced hyperalphalipoproteinemia and HDL remodeling in transgenic mice

High density lipoprotein (HDL) metabolism and lecithin:cholesterol acyltransferase (LCAT)-induced HDL remodeling were investigated in transgenic mice expressing human apolipoprotein (apo) AI or an apoAI/apoAII chimera in which the Arg123-Tyr166 domain of apoAI was substituted with the Ser12-Ala75 domain of apoAII. Expression of apoAI and of the apoAI/apoAII chimera resulted in a respective 3. 5-fold and 2.9-fold increase of HDL cholesterol. Human LCAT gene transfer into apoAI-transgenic mice resulted in a 5.1-fold increase of endogenous LCAT activity. This increase was associated with a 2. 4-fold increase of the cholesterol ester-to-free cholesterol ratio of HDL, a shift from HDL(3) to HDL(2), and a 2.4-fold increase of HDL cholesterol levels. Agarose gel electrophoresis revealed that human LCAT gene transfer into human apoAI-transgenic mice resulted in an increase of pre-beta-HDL and of pre-alpha-HDL. In contrast, human LCAT gene transfer did not affect cholesterol levels and HDL distribution profile in mice expressing the apoAI/apoAII chimera. Mouse LCAT did not "see" a difference between wild-type and mutant human apoAI, whereas human LCAT did, thus localizing the species-specific interaction in the central domain of apoAI. In conclusion, the Arg123-Tyr166 central domain of apoAI is not critical for in vivo lipoprotein association. It is, however, critical for LCAT-induced hyperalphalipoproteinemia and HDL remodeling independent of the lipid-binding properties of apoAI.     

Overexpression of lecithin:cholesterol acyltransferase in transgenic rabbits prevents diet-induced atherosclerosis.

Lecithin:cholesterol acyltransferase (LCAT) is a key plasma enzyme in cholesterol and high density lipoprotein (HDL) metabolism. Transgenic rabbits overexpressing human LCAT had 15-fold greater plasma LCAT activity that nontransgenic control rabbits. This degree of overexpression was associated with a 6.7-fold increase in the plasma HDL cholesterol concentration in LCAT transgenic rabbits. On a 0.3% cholesterol diet, the HDL cholesterol concentrations increased from 24 +/- 1 to 39 +/- 3 mg/dl in nontransgenic control rabbits (n = 10; P < 0.05) and increased from 161 +/- 5 to 200 +/- 21 mg/dl (P < 0.001) in the LCAT transgenic rabbits (n = 9). Although the baseline non-HDL concentrations of control (4 +/- 3 mg/dl) and transgenic rabbits (18 +/- 4 mg/dl) were similar, the cholesterol-rich diet raised the non-HDL cholesterol concentrations, reflecting the atherogenic very low density, intermediate density, and low density lipoprotein particles observed by gel filtration chromatography. The non-HDL cholesterol rose to 509 +/- 57 mg/dl in controls compared with only 196 +/- 14 mg/dl in the LCAT transgenic rabbits (P < 0.005). The differences in the plasma lipoprotein response to a cholesterol-rich diet observed in the transgenic rabbits paralleled the susceptibility to developing aortic atherosclerosis. Compared with nontransgenic controls, LCAT transgenic rabbits were protected from diet-induced atherosclerosis with significant reductions determined by both quantitative planimetry (-86%; P < 0.003) and quantitative immunohistochemistry (-93%; P < 0.009). Our results establish the importance of LCAT in the metabolism of both HDL and apolipoprotein B-containing lipoprotein particles with cholesterol feeding and the response to diet-induced atherosclerosis. In addition, these findings identify LCAT as a new target for therapy to prevent atherosclerosis.     

Lecithin:cholesterol acyltransferase activity, plasma and lipoprotein lipids and obesity in men and women

Lecithin:cholesterol acyltransferase (LCAT) activity, lipid concentration, lipoprotein lipid concentrations and cholesteryl ester linoleic acid proportion were determined in the plasma of 85 subjects randomly selected from a population during a health screen survey. Mean fractional LCAT rate was significantly higher in men than in women. Molar LCAT rate correlated with low density lipoprotein (LDL) cholesterol concentration in men and with nearly all lipoprotein lipid concentrations in women. Most of these relationships were dependent on plasma unesterified cholesterol (UC) concentration. Fractional LCAT rate was correlated only with HDL cholesterol concentration in women and this relation was dependent on the influence of obesity. An inverse relationship between plasma cholesteryl ester (PCE) linoleic acid proportion and molar LCAT rate in women was also explained by influences of obesity on the data. Both fractional and molar LCAT rates were positively correlated with obesity (Quetelet's Index and subscapular skinfold thickness) in women but not in men. This study showed the influence of sex on nearly all correlations involving LCAT activity in combined groups of men and women.