Electrospray ionization mass spectrometry identifies substrates and products of lipoprotein-associated phospholipase A2 in oxidized human low density lipoprotein
Electrospray ionization mass spectrometry identifies substrates and products of lipoprotein-associated phospholipase A2 in oxidized human low density lipoprotein
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DOI：
10.1074/jbc.m709970200
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发表时间：
2008-03-07
影响因子：
4.8
通讯作者：
Postle, Anthony D.
中科院分区：
文献类型：
--
作者：
Davis, Bill;Koster, Grielof;Postle, Anthony D.
越来越多的证据表明，低密度脂蛋白（LDL）氧化修饰的磷脂产物介导易损动脉粥样硬化病变内的炎症过程。脂蛋白相关磷脂酶A(2) （Lp-PLA(2)）存在于易损斑块区域，在那里它作用于磷脂氧化产物，产生促炎溶血磷脂和氧化的非酯化脂肪酸。这种关联以及循环中Lp-PLA(2)水平作为心血管疾病的独立预测因子的鉴定，为开发Lp-PLA(2)抑制剂治疗动脉粥样硬化提供了理论依据。在这里，我们报告了一项系统的分析，在缺乏和存在Lp-PLA(2)抑制剂的情况下，体外氧化对人LDL的磷脂酰胆碱（PC）组成的影响。质谱鉴定出三种浓度在LDL氧化过程中显著增强的PC。其中，一系列分子是Lp-PLA的主要底物，其峰位于m/z 594-666范围内，通过使用LTQ Orbitrap质谱仪进行精确的质量测量，确定为截断的PC氧化产物(2)。第二系列氧化产物，在m/z范围746-830的峰表示，通过LTQ Orbitrap分析鉴定为非截断的氧化pc，在数量上更丰富，但效率较低的Lp-PLA(2)底物。Lp-PLA(2)的主要PC产品，饱和lyso-PC和单不饱和lyso-PC，构成第三类。质谱分析证实，在人类动脉粥样硬化病变中存在许多这些pc，这表明它们可能被用作动脉粥样硬化疾病进展和对Lp-PLA(2)抑制剂治疗反应的体内标志物。
There is increasing evidence that modified phospholipid products of low density lipoprotein (LDL) oxidation mediate inflammatory processes within vulnerable atherosclerotic lesions. Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is present in vulnerable plaque regions where it acts on phospholipid oxidation products to generate the pro-inflammatory lysophsopholipids and oxidized non-esterified fatty acids. This association together with identification of circulating Lp-PLA(2) levels as an independent predictor of cardiovascular disease provides a rationale for development of Lp-PLA(2) inhibitors as therapy for atherosclerosis. Here we report a systematic analysis of the effects of in vitro oxidation in the absence and presence of an Lp-PLA(2) inhibitor on the phosphatidylcholine (PC) composition of human LDL. Mass spectrometry identifies three classes of PC whose concentration is significantly enhanced during LDL oxidation. Of these, a series of molecules, represented by peaks in the m/z range 594-666 and identified as truncated PC oxidation products by accurate mass measurements using an LTQ Orbitrap mass spectrometer, are the predominant substrates for Lp-PLA(2). A second series of oxidation products, represented by peaks in the m/z range 746-830 and identified by LTQ Orbitrap analysis as non-truncated oxidized PCs, are quantitatively more abundant but are less efficient Lp-PLA(2) substrates. The major PC products of Lp-PLA(2), saturated and mono-unsaturated lyso-PC, constitute the third class. Mass spectrometric analysis confirms the presence of many of these PCs within human atherosclerotic lesions, suggesting that they could potentially be used as in vivo markers of atherosclerotic disease progression and response to Lp-PLA(2) inhibitor therapy.