Cipollone Francesco, Mezzetti Andrea, Fazia Maria Luigia, Cuccurullo Chiara, Iezzi Annalisa, Ucchino Sante, Spigonardo Francesco, Bucci Marco, Cuccurullo Franco, Prescott Stephen M, Stafforini Diana M
Atherosclerosis Prevention Center, G. d'Annunzio University of Chieti, Chieti, Italy.
Arterioscler Thromb Vasc Biol. 2005 Aug;25(8):1665-70. doi: 10.1161/01.ATV.0000172632.96987.2d. Epub 2005 Jun 2.
The participation of 5-lipoxygenase (5-LO) in the development of atherosclerosis has been suggested by recent studies. However, a role for 5-LO as a modulator of atherosclerotic plaque instability has not been previously reported in humans. Thus, the aims of this study was to analyze the expression of 5-LO in human carotid plaques and to investigate the mechanism by which this enzyme could lead to plaque instability and rupture.
We obtained atherosclerotic plaques from 60 patients undergoing carotid endarterectomy. We divided the plaques into symptomatic and symptomatic according to clinical evidence of plaque instability. Clinical evidence of plaque instability was provided by the assessment of recent ischemic symptoms attributable to the stenosis and by the presence of ipsilateral cerebral lesion(s) determined by computed tomography. Plaques were analyzed for CD68+ macrophages, CD3+ T cells, alpha-actin+ smooth muscle cells, 5-LO, cyclooxygenase 2, matrix metalloproteinase (MMP)-2, and MMP-9 by immunohistochemical, immunoblotting, and densitometric analyses. MMP activity was assessed by zymography. Leukotriene (LT) B4 and collagen were quantified by ELISA and Sirius red polarization, respectively. The percentage of macrophage-rich and T-cell-rich areas was larger in symptomatic compared with asymptomatic patients (25+/-6% versus 8+/-4%, P<0.0001, and 74+/-17 versus 18+/-4 cell/mm2, P<0.003). 5-LO expression was higher in symptomatic compared with asymptomatic plaques (24+/-4% versus 6+/-3%, P<0.0001) and was associated with increased MMP-2 and MMP-9 expression (27+/-4% versus 7+/-3%, P<0.0001, and 29+/-5% versus 8+/-2%, P<0.0001) and activity and with decreased collagen content (6.9+/-2.4% versus 17.8+/-3.1%, P<0.01). Immunofluorescence showed that 5-LO and MMPs colocalize in activated macrophages. Notably, higher 5-LO in symptomatic plaques correlated with increased LTB4 production (18.15+/-3.56 versus 11.27+/-3.04 ng/g tissue, P<0.0001).
The expression of 5-LO is elevated in symptomatic compared with asymptomatic plaques and is associated with acute ischemic syndromes, possibly through the generation of LTB4, subsequent MMP biosynthesis, and plaque rupture.
近期研究提示5-脂氧合酶（5-LO）参与动脉粥样硬化的发展。然而，5-LO作为动脉粥样硬化斑块不稳定性调节因子在人类中的作用此前尚未见报道。因此，本研究旨在分析5-LO在人类颈动脉斑块中的表达，并探讨该酶导致斑块不稳定和破裂的机制。
我们从60例行颈动脉内膜切除术的患者中获取动脉粥样硬化斑块。根据斑块不稳定的临床证据将斑块分为有症状和无症状两类。斑块不稳定的临床证据通过评估近期因狭窄所致的缺血症状以及通过计算机断层扫描确定的同侧脑病变来提供。通过免疫组织化学、免疫印迹和光密度分析对斑块进行CD68 +巨噬细胞、CD3 + T细胞、α-肌动蛋白+平滑肌细胞、5-LO、环氧化酶2、基质金属蛋白酶（MMP）-2和MMP-9分析。通过酶谱法评估MMP活性。分别通过酶联免疫吸附测定和天狼星红偏振法定量白三烯（LT）B4和胶原蛋白。与无症状患者相比，有症状患者中富含巨噬细胞和富含T细胞的区域百分比更高（25±6%对8±4%，P<0.0001，以及74±17对18±4个细胞/mm2，P<0.003）。与无症状斑块相比，有症状斑块中5-LO表达更高（24±4%对6±3%，P<0.0001），并且与MMP-2和MMP-9表达增加（27±4%对7±3%，P<0.0001，以及29±5%对8±2%，P<0.0001）、活性增加以及胶原蛋白含量降低相关（6.9±2.4%对17.8±3.1%，P<0.01）。免疫荧光显示5-LO和MMPs在活化的巨噬细胞中共定位。值得注意的是，有症状斑块中较高的5-LO与LTB4产生增加相关（18.15±3.56对11.27±3.04 ng/g组织，P<0.0001）。
与无症状斑块相比，有症状斑块中5-LO的表达升高，并且可能通过LTB4的产生、随后的MMP生物合成和斑块破裂与急性缺血综合征相关。
