Department of Medicine, Baylor College of Medicine, Houston, TX, USA.
J Lipid Res. 2009 Sep;50(9):1735-43. doi: 10.1194/jlr.M800342-JLR200. Epub 2009 Apr 9.
Plasma levels of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and oxidized low density lipoprotein (oxLDL) have been identified as risk factors for cardiovascular disease. Lp-PLA(2) is the sole enzyme responsible for the hydrolysis of oxidized phospholipids on LDL particles in atherosclerotic plaques. We have studied the relationship between Lp-PLA(2) and oxLDL in carotid endarterectomy (CEA) tissues and in matched plasmas. In extracts from CEA anatomical segments, the levels of oxLDL were significantly associated with the levels of Lp-PLA(2) protein (r = 0.497) and activity (r = 0.615). OxLDL and Lp-PLA(2) mass/activity were most abundant in the carotid bifurcation and internal segments where plaque was most abundant. In extracts from CEA atheroma, the levels of oxLDL and Lp-PLA(2) were significantly correlated (r = 0.634). In matched plasma and atheroma extracts, the levels of Lp-PLA(2) were negatively correlated (r = - 0.578). The ratio of Lp-PLA(2) to oxLDL was higher in atheromatous tissue (277:1) than in normal tissue (135:1) and plasma (13:1). Immunohistochemical experiments indicated that in plaques, oxLDL and Lp-PLA(2) existed in overlapping but distinctly different distribution. Fluorescence microscopy showed both oxLDL and Lp-PLA(2) epitopes on the same LDL particle in plasma but not in plaque. These results suggest that the relationship between Lp-PLA(2) and oxLDL in the atherosclerotic plaque is different from that in the plasma compartment.
脂蛋白相关磷脂酶 A2（Lp-PLA2）和氧化型低密度脂蛋白（oxLDL）的血浆水平已被确定为心血管疾病的危险因素。Lp-PLA2 是唯一负责水解动脉粥样硬化斑块中 LDL 颗粒上氧化磷脂的酶。我们研究了颈动脉内膜切除术（CEA）组织和匹配血浆中 Lp-PLA2 与 oxLDL 之间的关系。在 CEA 解剖段的提取物中，oxLDL 水平与 Lp-PLA2 蛋白水平（r = 0.497）和活性（r = 0.615）显著相关。oxLDL 和 Lp-PLA2 质量/活性在斑块最丰富的颈动脉分叉和内段最为丰富。在 CEA 动脉粥样硬化斑块的提取物中，oxLDL 和 Lp-PLA2 水平显著相关（r = 0.634）。在匹配的血浆和动脉粥样硬化斑块提取物中，Lp-PLA2 水平呈负相关（r = -0.578）。在动脉粥样硬化组织中（277:1），Lp-PLA2 与 oxLDL 的比值高于正常组织（135:1）和血浆（13:1）。免疫组织化学实验表明，在斑块中，oxLDL 和 Lp-PLA2 存在重叠但明显不同的分布。荧光显微镜显示，在血浆中，同一个 LDL 颗粒上既有 oxLDL 又有 Lp-PLA2 表位，但在斑块中没有。这些结果表明，在动脉粥样硬化斑块中 Lp-PLA2 和 oxLDL 之间的关系与在血浆区室中不同。
