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Vascular Protective Effects of PPAR Ligands ; Anti-Polymorphonuclear Leukocyte Activity

PPAR 配体的血管保护作用；

基本信息

批准号：
18590825
负责人：
MATSUOKA Hidehiro
金额：
$ 2.57万
依托单位：
Kurume University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18590825/
关键词：
inflammation endothelium oxidative stress neutrophils atherosclerosis

项目摘要

Several lines of evidence indicate that inflammation plays a pivotal role in the process of atherosclerosis. Although local inflammation of vulnerable plaque is responsible for the development of acute coronary syndrome, systemic inflammatory process as estimated by high sensitive C-reactive protein is closely associated with later cardiovascular events in subjects with hypercholesterolemia. Although precise mechanisms which link systemic inflammation to vascular diseases remain to be elucidated, reactive oxygen species (ROS) play a pivotal role in inflammation-mediated vascular injury. Polymorphonuclear leukocytes (PMN) are ubiquitous effector cells in numerous inflammatory conditions. Relevance of PMN function is usually thought in terms of host-defense in bacterial infections. PMN produce a large amount of ROS through the respiratory burst and cause lipid peroxidation. In addition, upon stimulation, PMN release cytokines which promote endothelial cell activation and hence cell-to-ce … More ll adhesion. Collectively, these findings suggest a possible role of PMN in the development of vascular diseases via impairment of endothelial function. Indeed, widespread activation of PMN was demonstrated in subjects with hypercholesterolemia. Three-hydroxyl-3-methylglutanyl coenzyme A (HMG-CoA) reductase inhibitors (statins) significantly decrease cardiovascular mortality associated with hypercholesterolemia. In vitro studies have shown that stating exert beneficial effects on vascular diseases by inhibiting leukocyte rolling and adhesion and by stabilizing endothelial NO synthase (eNOS) posttranslationally. Several clinical trials revealed that statins decrease markers of inflammation/oxidative stress and restore endothelium-dependent vasodilation in the placebo controlled design. However, whether the restorations of endothelial function by statin are attributable to LDL reduction or to its pleiotropic effects remain to be tested by the alternative active treatment arm. Accordingly, we hypothesized that i) circulating PMN in hypercholesterolemia are activated, leading to oxidative stress in vivo and hence impair endothelial function, and that if so ii) statins may restore the PMN-mediated endothelial dysfunction independently of LDL reduction. To test these hypotheses, we measured PMN activity, oxidative stress, and endothelial function in subjects hypercholesterolemia and their age-matched controls and we conducted a prospective randomized study using two different classes of lipid lowering agents, fluvastatin and colestimide, in a cross-over design. Moreover, to investigate the direct interrelation between PMN and endothelia, cell adhesion and eNOS phosphorylation as a process of eNOS activation in cultured human endothelial cells were investigated before and after ex vivo exposure of PMN obtained from hypercholesterolemic subjects with or without fluvastatin treatment. Three months administration of fluvastatin or colestimide lowered LDL to the same levels. Endothelial function was restored and the suscepitibility of LDL to oxidation was diminished only in fluvastation-treated subjects. Similarly, fluvastatin attenuated ROS release from PMN, whereas colestimide had no effects on either lipid peroxidation or ROS release. Furthermore, co-incubation with PMN obtained from HC significantly impaired eNOS Ser1177 phosphorylation of HUVEC comared to controls. Fluvastin treatment attenuated cell adhesion, and restored eNOS Ser1177 phosphorylation in HC. Thus, our results raise a novel concept that circulating PMN may directly attack endothelia and play a pivotal role in the pathogenesis of atherosclerosis.Next, we investigated PMN activity in general population. Myeloperoxidase (MPO), a hemoprotein abunbantly expressed by polymorphonuclear leukocytes and secreted during activation, possesses potent proinflammatory properties. It has been shown that serum MPO levels are elevated in patients with acute coronary syndrome and that its levels predict subsequent cardiovascular events. Although its precise mechanism remains uknown, in vitro MPO catalytically consumes endothelium-derived nitric oxide. In apparently healthy subjects, coronary risk factors were evaluated. Endothelial function and arterial compliance were estimated by flow-mediated vasodilation of the brachial artery and stiffness beta of the common carotid artery, by vascular ultrasonography, respectively. Serum MPO levels were determined by ELISA. Univariate analyses revealed that MPO was significantly and positively correlated with age and high-sensitivity C-creative protein (hsCRP), but not associated with gender, lipid profile, plasma glucose or smoking habit. There was significant positive relationship between MPO and stiffness beta. MPO was also inversely correlated with flow-mediated vasodilation. Multiple regression analysis revealed that MPO was an independent determinant of flow-mediated vasodilation, irrespective of classical risk and hsCRP. Thus, MPO was closely associated with aging and systemic inflammation and correlated with indices of arterial compliance. Furthermore, MPO was an independent risk factor of endothelial function. Our results suggest that MPO, neutrophil-derived peroxidase, may promote atherosclerosis via endothelial dysfunction.Peroxisome proliferator activated receptor (PPAR) gamma plays a pivotal role in vascular inflammatory process. Indeed, stimulation of the PPAR ligand improved endothelial function partly mediated by renin-angiotensin (RA) axis. Recently, a number of study demonstrated that blocking AT(1)R and activating PPAR gamma signaling attenuate asymmetrical dimethylarginine (ADMA)-dimethylarginine dimethylaminohydrolase (DDAH)-system, an endogenous inhibitor of nitric oxide. Therefore, we investigated the regulatory mechanisms of ADMA-DDAH system in the model of chronic kidney disease. Plasma ADMA was elevated and DDHA activity was reduced in the CKD model. Chronic administration of AT(1)R blocher restored DDAH activity and decreased ADMA. Thus, the crosstalk among PPAR-ADMA-DDAH system-RA axis may play a role in the progression of vascular disease.As a future prospect, we are now developing our projects for clinical application. For this purpose, we have organized the committee on the standardized-measurement of endothelial function by the ultrasonography-guided flow mediated vasodilation, and published the statement. The multi-center clinical trial using FMD, as well as simultenous several workshops for the methods will be conducted next year. Less

多项证据表明，炎症在动脉粥样硬化过程中起着关键作用。虽然易损斑块的局部炎症是急性冠状动脉综合征发生的原因，但高敏感c反应蛋白估计的全身性炎症过程与高胆固醇血症患者后来的心血管事件密切相关。尽管将全身性炎症与血管疾病联系起来的确切机制仍有待阐明，但活性氧（ROS）在炎症介导的血管损伤中起着关键作用。多形核白细胞（PMN）是多种炎症条件下普遍存在的效应细胞。PMN功能的相关性通常被认为是在细菌感染的宿主防御方面。PMN通过呼吸爆发产生大量ROS，引起脂质过氧化。此外，在刺激后，PMN释放细胞因子，促进内皮细胞活化，从而促进细胞间的粘附。总的来说，这些发现表明PMN可能通过内皮功能损伤在血管疾病的发展中起作用。事实上，在高胆固醇血症患者中证实了PMN的广泛激活。3-羟基-3-甲基戊酰辅酶A （HMG-CoA）还原酶抑制剂（他汀类药物）可显著降低与高胆固醇血症相关的心血管死亡率。体外研究表明，他汀通过抑制白细胞滚动和粘附以及稳定内皮细胞一氧化氮合酶（eNOS）对血管疾病有有益作用。几项临床试验显示，在安慰剂对照设计中，他汀类药物可降低炎症/氧化应激标志物，恢复内皮依赖性血管舒张。然而，他汀类药物对内皮功能的恢复是由于LDL的降低还是由于其多效性，仍有待于替代活性治疗组的检验。因此，我们假设i)高胆固醇血症中循环PMN被激活，导致体内氧化应激，从而损害内皮功能，如果是这样，ii)他汀类药物可以恢复PMN介导的内皮功能障碍，而不依赖于LDL的降低。为了验证这些假设，我们测量了高胆固醇血症受试者及其年龄匹配对照的PMN活性、氧化应激和内皮功能，并在交叉设计中使用两种不同类型的降脂剂氟伐他汀和colestimide进行了一项前瞻性随机研究。此外，为了研究PMN与内皮之间的直接关系，我们研究了高胆固醇血症患者在体外暴露PMN前后和不接受氟伐他汀治疗前后，培养的人内皮细胞中细胞粘附和eNOS磷酸化作为eNOS激活过程。服用氟伐他汀或colestimide三个月可将LDL降至相同水平。内皮功能恢复，LDL对氧化的敏感性仅在氟伐他汀治疗的受试者中降低。类似地，氟伐他汀降低PMN的ROS释放，而colestimide对脂质过氧化和ROS释放均无影响。此外，与对照组相比，与HC获得的PMN共孵育显著损害了HUVEC的eNOS Ser1177磷酸化。氟伐他汀可减弱HC细胞粘附，恢复eNOS Ser1177磷酸化。因此，我们的研究结果提出了一个新的概念，即循环PMN可能直接攻击内皮细胞，并在动脉粥样硬化的发病机制中发挥关键作用。接下来，我们调查了普通人群的PMN活性。髓过氧化物酶（MPO）是一种由多形核白细胞大量表达并在激活过程中分泌的血红蛋白，具有强效的促炎特性。研究表明，急性冠状动脉综合征患者血清MPO水平升高，其水平可预测随后的心血管事件。尽管其确切的机制尚不清楚，体外MPO催化消耗内皮来源的一氧化氮。在表面健康的受试者中，评估冠状动脉危险因素。分别通过血管超声检查肱动脉血流介导的血管舒张和颈总动脉的僵硬度来评估内皮功能和动脉顺应性。ELISA法测定血清MPO水平。单因素分析显示，MPO与年龄和高敏感性c -生成蛋白（hsCRP）显著正相关，但与性别、血脂、血糖或吸烟习惯无关。MPO与刚度β呈显著正相关。MPO也与血流介导的血管舒张呈负相关。多元回归分析显示MPO是血流介导的血管舒张的独立决定因素，与经典风险和hsCRP无关。因此，MPO与衰老和全身性炎症密切相关，并与动脉顺应性指标相关。此外，MPO是内皮功能的独立危险因素。我们的研究结果表明MPO，中性粒细胞衍生的过氧化物酶，可能通过内皮功能障碍促进动脉粥样硬化。过氧化物酶体增殖物激活受体(PPAR) γ在血管炎症过程中起关键作用。事实上，刺激PPAR配体可部分改善肾素-血管紧张素（RA）轴介导的内皮功能。最近，许多研究表明，阻断AT(1)R和激活PPAR γ信号会减弱内源性一氧化氮抑制剂不对称二甲基精氨酸(ADMA)-二甲基精氨酸二甲氨基水解酶(DDAH)-系统。因此，我们研究了ADMA-DDAH系统在慢性肾脏疾病模型中的调节机制。在CKD模型中，血浆ADMA升高，dha活性降低。长期给药AT(1)R受体阻滞剂可恢复DDAH活性，降低ADMA。因此，PPAR-ADMA-DDAH系统- ra轴之间的串扰可能在血管疾病的进展中起作用。展望未来，我们正在开展临床应用项目。为此，我们组织了超声引导血流介导的血管舒张内皮功能标准化测量委员会，并发表了声明。使用口蹄疫的多中心临床试验，以及同时举办的几次研讨会将于明年进行。少