Camaré Caroline, Augé Nathalie, Pucelle Mélanie, Saint-Lebes Bertrand, Grazide Marie-Hélène, Nègre-Salvayre Anne, Salvayre Robert
Inserm UMR-1048, CHU Rangueil, BP 84225, 31432 Toulouse Cedex 4, France; University of Toulouse, Faculty of Medicine, Biochemistry Department, Toulouse, France; CHU Toulouse, Rangueil, Toulouse, France.
Inserm UMR-1048, CHU Rangueil, BP 84225, 31432 Toulouse Cedex 4, France.
Free Radic Biol Med. 2016 Apr;93:204-16. doi: 10.1016/j.freeradbiomed.2016.02.006. Epub 2016 Feb 5.
Capillaries of the external part of the normal arterial wall constitute the vasa vasorum network. In atherosclerotic lesions, neovascularization occurs in areas of intimal hyperplasia where it may promote plaque expansion, and intraplaque hemorrhage. Oxidized LDL that are present in atherosclerotic areas activate various angiogenic signaling pathways, including reactive oxygen species and the sphingosine kinase/sphingosine-1-phosphate pathway. We aimed to investigate whether oxidized LDL-induced angiogenesis requires neutral sphingomyelinase-2 activation and the neutral sphingomyelinase-2/sphingosine kinase-1 pathway. The role of neutral sphingomyelinase-2 in angiogenic signaling was investigated in Human Microvascular Endothelial Cells (HMEC-1) forming capillary tube on Matrigel and in vivo in the Matrigel plug assay in C57BL/6 mice and in the chicken chorioallantoic membrane model. Low concentration of human oxidized LDL elicits HMEC-1 capillary tube formation and neutral sphingomyelinase-2 activation, which were blocked by neutral sphingomyelinase-2 inhibitors, GW4869 and specific siRNA. This angiogenic effect was mimicked by low concentration of C6-Ceramide and was inhibited by sphingosine kinase-1 inhibitors. Upstream of neutral sphingomyelinase-2, oxidized LDL-induced activation required LOX-1, reactive oxygen species generation by NADPH oxidase and p38-MAPK activation. Inhibition of sphingosine kinase-1 blocked the angiogenic response and triggered HMEC-1 apoptosis. Low concentration of oxidized LDL was angiogenic in vivo, both in the Matrigel plug assay in mice and in the chorioallantoic membrane model, and was blocked by GW4869. In conclusion, low oxLDL concentration triggers sprouting angiogenesis that involves ROS-induced activation of the neutral sphingomyelinase-2/sphingosine kinase-1 pathway, and is effectively inhibited by GW4869.
正常动脉壁外部的毛细血管构成了血管滋养管网络。在动脉粥样硬化病变中，新生血管形成于内膜增生区域，这可能促进斑块扩展和斑块内出血。存在于动脉粥样硬化区域的氧化型低密度脂蛋白（oxLDL）激活多种血管生成信号通路，包括活性氧和鞘氨醇激酶/鞘氨醇-1-磷酸通路。我们旨在研究氧化型低密度脂蛋白诱导的血管生成是否需要中性鞘磷脂酶-2激活以及中性鞘磷脂酶-2/鞘氨醇激酶-1通路。在人微血管内皮细胞（HMEC-1）在基质胶上形成毛细血管管以及在C57BL/6小鼠的基质胶栓试验和鸡胚绒毛尿囊膜模型中体内研究了中性鞘磷脂酶-2在血管生成信号传导中的作用。低浓度的人氧化型低密度脂蛋白引发HMEC-1毛细血管管形成和中性鞘磷脂酶-2激活，这被中性鞘磷脂酶-2抑制剂GW4869和特异性小干扰RNA（siRNA）阻断。这种血管生成作用被低浓度的C6-神经酰胺模拟，并被鞘氨醇激酶-1抑制剂抑制。在中性鞘磷脂酶-2上游，氧化型低密度脂蛋白诱导的激活需要凝集素样氧化型低密度脂蛋白受体1（LOX-1）、烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶产生活性氧以及p38丝裂原活化蛋白激酶（p38-MAPK）激活。抑制鞘氨醇激酶-1阻断血管生成反应并引发HMEC-1细胞凋亡。低浓度的氧化型低密度脂蛋白在小鼠的基质胶栓试验和绒毛尿囊膜模型中体内具有血管生成作用，并被GW4869阻断。总之，低浓度氧化型低密度脂蛋白触发芽生血管生成，涉及活性氧诱导的中性鞘磷脂酶-2/鞘氨醇激酶-1通路激活，并被GW4869有效抑制。
