Circulating Polymorphonuclear Leukocytes Cell as a Risk Factor for Endothelial injury in Humans

动脉粥样硬化被认为是一种全身性炎症过程。虽然降脂治疗在高胆固醇血症模型中部分通过热休克蛋白90介导的内皮一氧化氮合酶磷酸化来恢复内皮功能，但确切的机制仍有待阐明。在目前的体内和体外研究中，我们研究了多形核白细胞（PMN）和内皮功能之间的可能联系以及降脂治疗的效果。在研究的第一部分，无其他冠心病危险因素的高胆固醇血症受试者被随机分为氟伐他汀组和考来替胺组。三个月的氟伐他汀或考来替胺给药以类似的方式降低LDL（两者p= 0.0001）。通过肱动脉血流介导的血管舒张评估的内皮功能仅在氟伐他汀治疗的受试者中恢复（p=.0001）。同样，氟伐他汀改善了LDL对氧化的敏感性（p= 0.007），并减弱了PMN释放超氧化物（p= 0.001），而考来替胺对脂质过氧化或炎症细胞活性没有影响。在体外研究的第二部分中，蛋白质印迹分析显示，从高胆固醇血症受试者获得的PMN暴露损害了培养的内皮细胞中一氧化氮合酶（eNOS）的磷酸化，而慢性氟伐他汀治疗使eNOS磷酸化正常化（p= 0.01）。因此，他汀类药物通过其抗炎特性改善内皮功能，而不依赖于LDL的降低。我们的结果提出了一个新的概念，即循环中释放大量超氧化物的PMN可能直接攻击内皮细胞，在动脉粥样硬化的发病机制中起着关键作用。

Atherosclerosis is considered as a systemic inflammatory process. Although lipid lowering therapies restore endothelial function partly through hsp90-mediated phosphorylation of endothelial nitric synthase in hypercholesterolemic models, precise mechanisms remain to be elucidated. In the present in vivo and ex vivo studies, we investigated a possible link between polymorphonuclear leukocytes (PMN) and endothelial function and the effects of lipid lowering therapies. In the first part of study, hypercholesterolemic subjects without other coronary risk factors were randomized to have fluvastatin or colestimide in a crossover design. Three months administration of fluvastatin or colestimide lowered LDL in a similar manner (p=.0001 for both). Endothelial function, estimated by flow-mediated vasodilation of the brachial artery, was restored only in fluvastatin-treated subjects (p=.0001). Similarly, fluvastatin improved the susceptibility of LDL to oxidation (p=.007) and attenuated superoxide release from PMN (p=.001), whereas colestimide had no effects on either lipid peroxidation or inflammatory cell activity. In the second part of ex vivo study, western blot analysis revealed that the exposure of PMN obtained from hypercholesterolemic subjects impaired the phosphorylation of nitric oxide synthase (eNOS) in cultured endothelial cells, whereas chronic fluvastatin treatment normalized eNOS phospholylation (p=.01). Thus, statin improved endothelial function by its anti-inflammatory properties, independent of LDL reduction. Our results raise a novel concept that circulating PMN, which burst a large amount of superoxide, may directly attack endothelia and play a pivotal role in the pathogenesis of atherosclerosis.