Wihuri Research Institute, Biomedicum Helsinki, Haartmaninkatu 8, Helsinki, Finland.
Wihuri Research Institute, Biomedicum Helsinki, Haartmaninkatu 8, Helsinki, Finland; Translational Cancer Medicine Program, Research Programs Unit, University of Helsinki, Finland.
Atherosclerosis. 2021 Jun;327:87-99. doi: 10.1016/j.atherosclerosis.2021.04.007. Epub 2021 May 2.
Secretory phospholipase A (PLA) hydrolyzes LDL phospholipids generating modified LDL particles (PLA-LDL) with increased atherogenic properties. Exocytosis of Weibel-Palade bodies (WPB) releases angiopoietin 2 (Ang2) and externalizes P-selectin, which both play important roles in vascular inflammation. Here, we investigated the effects of PLA-LDL on exocytosis of WPBs.
Human coronary artery endothelial cells (HCAECs) were stimulated with PLA- LDL, and its uptake and effect on Ang2 release, leukocyte adhesion, and intracellular calcium levels were measured. The effects of PLA-LDL on Ang2 release and WPB exocytosis were measured in and ex vivo in mice.
Exposure of HCAECs to PLA-LDL triggered Ang2 secretion and promoted leukocyte-HCAEC interaction. Lysophosphatidylcholine was identified as a critical component of PLA-LDL regulating the WPB exocytosis, which was mediated by cell-surface proteoglycans, phospholipase C, intracellular calcium, and cytoskeletal remodeling. PLA-LDL also induced murine endothelial WPB exocytosis in blood vessels in and ex vivo, as evidenced by secretion of Ang2 in vivo, P-selectin translocation to plasma membrane in intact endothelial cells in thoracic artery and tracheal vessels, and reduced Ang2 staining in tracheal endothelial cells. Finally, in contrast to normal human coronary arteries, in which Ang2 was present only in the endothelial layer, at sites of advanced atherosclerotic lesions, Ang2 was detected also in the intima, media, and adventitia.
Our studies reveal PLA-LDL as a potent agonist of endothelial WPB exocytosis, resulting in increased secretion of Ang2 and translocation of P-selectin. The results provide mechanistic insight into PLA-LDL-dependent promotion of vascular inflammation and atherosclerosis.
分泌型磷脂酶 A（PLA）水解 LDL 磷脂生成具有增加的致动脉粥样硬化特性的修饰性 LDL 颗粒（PLA-LDL）。Weibel-Palade 体（WPB）的胞吐作用释放血管生成素 2（Ang2）并使 P-选择素外化，这两者在血管炎症中都发挥着重要作用。在此，我们研究了 PLA-LDL 对 WPB 胞吐作用的影响。
用 PLA-LDL 刺激人冠状动脉内皮细胞（HCAEC），并测量其摄取和对 Ang2 释放、白细胞黏附以及细胞内钙离子水平的影响。还在体内和体外小鼠中测量了 PLA-LDL 对 Ang2 释放和 WPB 胞吐作用的影响。
暴露于 PLA-LDL 的 HCAEC 触发了 Ang2 的分泌，并促进了白细胞-HCAEC 相互作用。溶血磷脂酰胆碱被鉴定为调节 WPB 胞吐作用的 PLA-LDL 的关键成分，该作用由细胞表面糖蛋白、磷脂酶 C、细胞内钙离子和细胞骨架重塑介导。PLA-LDL 还诱导了体内血管中以及体内和体外的小鼠内皮 WPB 胞吐作用，表现为体内 Ang2 的分泌、胸主动脉和气管血管中完整内皮细胞的 P-选择素向质膜转位以及气管内皮细胞中 Ang2 染色减少。最后，与正常人类冠状动脉不同，在正常冠状动脉中，Ang2 仅存在于内皮细胞层，在进展性动脉粥样硬化病变部位，还检测到 Ang2 存在于内膜、中膜和外膜中。
我们的研究揭示了 PLA-LDL 作为内皮 WPB 胞吐作用的有效激动剂，导致 Ang2 分泌增加和 P-选择素转位。这些结果为 PLA-LDL 依赖性促进血管炎症和动脉粥样硬化提供了机制上的见解。
