Li Shi, Zhong Mingmei, Yuan Yuan, Zhang Lin
ICU, The Third Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230061, P.R. China.
The Central Laboratory of Binhu Hospital, The Third Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230061, P.R. China.
Exp Ther Med. 2018 Dec;16(6):4729-4736. doi: 10.3892/etm.2018.6810. Epub 2018 Oct 1.
Angiopoietin-2 (Ang-2) is a Tie-2 ligand that destabilizes vascular structures, enhances vascular permeability and induces vascular regression and endothelial cell apoptosis. Although there is evidence for the involvement of the Ang/Tie2 axis in acute lung injury (ALI), the underlying mechanisms involved in Ang-2-induced cell apoptosis are not well understood. In this study, whether Ang-2 contributes to microvascular endothelial cell injury and mediates lipopolysaccharide (LPS)-induced endothelial cell apoptosis and its associated signaling pathways was investigated. Exposure of rat pulmonary microvascular endothelial cells (RPMVECs) to LPS, Ang-2 and related inhibitors was performed to measure the expression levels of Ang-2, the activation of mitogen-activated protein kinases (MAPKs), the phosphorylation of extracellular signal-regulated kinase (ERK)1/2, and expression of the apoptosis-related proteins Bax and Bcl-2 using western blotting, reverse transcription-quantitative polymerase chain reaction, flow cytometry and fluorescence microscopy. The expression of Ang-2 in the RPMVECs was increased by LPS independent of time. The phosphorylation of p38 MAPK and ERK1/2 was significantly upregulated and the activation of apoptosis-related proteins Bax and Bcl was mediated by Ang-2. In addition, inhibition of the p38 pathway by SB203580 attenuated the Ang-2-mediated cell apoptosis, but inhibition of the ERK1/2 pathway by PD98059 exerted an anti-apoptotic effect against Ang-2. In conclusion, LPS-induced apoptosis is partly mediated via stimulation of p38 and ERK1/2 signaling pathways, where Ang-2 acts an inflammation-related factor to participate in the course of cell apoptosis in RPMVECs.
血管生成素-2（Ang-2）是一种Tie-2配体，可破坏血管结构的稳定性，增强血管通透性，并诱导血管消退和内皮细胞凋亡。尽管有证据表明Ang/Tie2轴参与急性肺损伤（ALI），但Ang-2诱导细胞凋亡的潜在机制尚不清楚。在本研究中，探讨了Ang-2是否会导致微血管内皮细胞损伤，介导脂多糖（LPS）诱导的内皮细胞凋亡及其相关信号通路。将大鼠肺微血管内皮细胞（RPMVECs）暴露于LPS、Ang-2及相关抑制剂中，通过蛋白质免疫印迹法、逆转录-定量聚合酶链反应、流式细胞术和荧光显微镜检测Ang-2的表达水平、丝裂原活化蛋白激酶（MAPKs）的激活、细胞外信号调节激酶（ERK）1/2的磷酸化以及凋亡相关蛋白Bax和Bcl-2的表达。LPS可使RPMVECs中Ang-2的表达随时间增加。p38 MAPK和ERK1/2的磷酸化显著上调，凋亡相关蛋白Bax和Bcl的激活由Ang-2介导。此外，SB203580抑制p38通路可减轻Ang-2介导的细胞凋亡，但PD98059抑制ERK1/2通路对Ang-2具有抗凋亡作用。总之，LPS诱导的细胞凋亡部分是通过刺激p38和ERK1/2信号通路介导的，其中Ang-2作为一种炎症相关因子参与RPMVECs的细胞凋亡过程。
