TNF-α促进内皮源性微体的数量与ICAM-1表达

TNF-α promotes the quantity and ICAM-1 expression of endothelial microparticles

目的探讨高张应变调控的肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)对内皮源性微体(endothelial microparticles,EMPs)数量与表面细胞间黏附分子-1(intercellular cell adhesion molecule-1,ICAM-1)表达的作用。方法采用Flexercell细胞张应变加载系统对大鼠胸主动脉内皮细胞(endothelial cells,ECs)分别施加5%(模拟正常生理状态)和18%(模拟高血压状态)幅度的周期性张应变,加载频率均为1.25 Hz,加载持续时间为24 h,实时PCR检测不同幅度张应变条件下ECs的TNF-αmRNA表达水平。之后应用TNF-α刺激大鼠胸主动脉ECs,收集上清液,超速离心提取得到内皮源性微体(endothelial microparticles,EMPs);用亲脂性苯乙烯基(lipophilic styryl)以及透射电镜对EMPs进行形态鉴定;流式细胞术对TNF-α刺激产生的Annexin V阳性EMPs进行计数,并检测EMPs表面ICAM-1的表达。结果与5%正常张应变组相比,18%高张应变条件下ECs的TNF-α表达水平显著上升。TNF-α能够显著上调ECs产生Annexin V阳性的EMPs数量,且TNF-α刺激ECs产生的EMPs表面ICAM-1表达量显著增加。结论高张应变条件下ECs高表达TNF-α可能介导了EMPs产生和表面ICAM-1高表达。研究结果为后续探讨EMPs在血管重建力学生物学机制中的作用提供新的实验证据。

Objective To study the role of cyclic strain-modulated tumor necrosis factor-α （TNF-α） played in the quantity and intercellular cell adhesion molecule-1 （ ICAM-1 ） expression of endothelial microparticles （EMPs）. Methods The endothelial cells （ECs） primarily cultured from rat aorta were applied with 5% cyclic strain （to simulate normal physiological condition） and 18% cyclic strain （to simulate hyper-tension condition）, respectively, by using FX-4000T cyclic stain loading system for 24 hours at the loading frequency of 1,25 Hz, The mRNA expression of TNF-α under different amplitudes of cyclic strain was determined by real time-PCR. The TNF-α was then used to stimulate the ECs from rat aorta, and the supernatants were collected and ultracentrifuged to get endothelial microparticles （ I=MPs）, which were then identified by lipophilic styryl membrane staining and transmission electron microscope for morphological identification. The quantities of Annexin V positive EMPs under TNF-α stimulation were counted by flow cytometer and ICAM-1 expression on EMPs was detected as well. Results Compared with the 5% normal cyclic strain, under 18% high cyclic strain condition,the mRNA expression of TNF-α in ECs increased significantly. TNF-α could then significantly up-regulate the production of Annexin V positive EMPs and promote the expression of ICAM-1 on EMPs. Conclusions The over-expression of TNF-α in ECs under high cyclic strain might mediate the high production of EMPs and over-expression of ICAM-1 on EMPs. The research findings will provide new experiment evidence for further studying the role of EPCs in the mechanobiological mechanism of vascular remodeling.