背景:危重病与器官衰竭有关,其中内皮通透性过高和组织水肿起主要作用。内皮血管生成素/Tie2系统,内皮通透性的调节剂,在危重疾病期间失衡。据报道,循环血管生成素-2水平升高,Tie2受体水平降低,但目前尚不清楚它们是否会引起独立于其他危重疾病相关改变的水肿.因此,我们研究了正常条件下血管生成素-2给药和/或降低Tie2表达对微血管渗漏和水肿的影响.
方法:部分缺失Tie2(杂合外显子9缺失,Tie2+/-)和野生型对照(Tie2+/+)静脉内接受24或72μg/g血管生成素-2或PBS作为对照(每组n=12)。微血管渗漏和水肿通过伊文思蓝染料(EBD)外渗和湿干重量比确定,分别,在肺和肾脏。通过ELISA和RT-qPCR确定与内皮血管生成素/Tie2信号相关的分子的表达。
结果:在Tie2+/+小鼠中,血管生成素-2给药增加EBD外渗(154%,p<0.05)和湿干重比(133%,p<0.01)在肺部,但与PBS相比,肾脏中没有。Tie2+/-小鼠的肺功能较高(143%,p<0.001),但不是肾EBD外渗,与野生型对照小鼠相比,而在肺部观察到更明显的湿干重量比(155%,p<0.0001),相比之下,肾脏的湿干重比稍高(106%,p<0.05)。血管生成素-2给Tie2+/-小鼠没有进一步增加肺EBD外渗,肺湿干重比,或肾脏湿干重量比。有趣的是,与接受PBS的Tie2+/-小鼠相比,血管生成素-2施用导致Tie2+/-小鼠中肾EBD外渗增加。血管生成素-2给药和Tie2的部分缺失均不影响循环血管生成素-1,可溶性Tie2,VEGF和NGAL以及血管生成素-1,-2,Tie1,VE-PTP的基因表达,ELF-1,Ets-1,KLF2,GATA3,MMP14,Runx1,VE-cadherin,VEGFα和NGAL,除了Tie2的基因和蛋白质表达外,与Tie2/-小鼠相比,Tie2/-小鼠的基因和蛋白质表达降低。
结论:在小鼠中,在微血管渗漏和水肿方面,与肾脏相比,肺的微血管更容易受到血管生成素2和Tie2部分缺失的影响。
Critical illness is associated with organ failure, in which endothelial hyperpermeability and tissue edema play a major role. The endothelial angiopoietin/Tie2 system, a regulator of endothelial permeability, is dysbalanced during critical illness. Elevated circulating angiopoietin-2 and decreased Tie2 receptor levels are reported, but it remains unclear whether they cause edema independent of other critical illness-associated alterations. Therefore, we have studied the effect of angiopoietin-2 administration and/or reduced Tie2 expression on microvascular leakage and edema under normal conditions.
Transgenic male mice with partial deletion of Tie2 (heterozygous exon 9 deletion, Tie2+/-) and wild-type controls (Tie2+/+) received 24 or 72 pg/g angiopoietin-2 or PBS as control (n = 12 per group) intravenously. Microvascular leakage and edema were determined by Evans blue dye (EBD) extravasation and wet-to-dry weight ratio, respectively, in lungs and kidneys. Expression of molecules related to endothelial angiopoietin/Tie2 signaling were determined by ELISA and RT-qPCR.
In Tie2+/+ mice, angiopoietin-2 administration increased EBD extravasation (154 %, p < 0.05) and wet-to-dry weight ratio (133 %, p < 0.01) in lungs, but not in the kidney compared to PBS. Tie2+/- mice had higher pulmonary (143 %, p < 0.001), but not renal EBD extravasation, compared to wild-type control mice, whereas a more pronounced wet-to-dry weight ratio was observed in lungs (155 %, p < 0.0001), in contrast to a minor higher wet-to-dry weight ratio in kidneys (106 %, p < 0.05). Angiopoietin-2 administration to Tie2+/- mice did not further increase pulmonary EBD extravasation, pulmonary wet-to-dry weight ratio, or renal wet-to-dry weight ratio. Interestingly, angiopoietin-2 administration resulted in an increased renal EBD extravasation in Tie2+/- mice compared to Tie2+/- mice receiving PBS. Both angiopoietin-2 administration and partial deletion of Tie2 did not affect circulating angiopoietin-1, soluble Tie2, VEGF and NGAL as well as gene expression of angiopoietin-1, -2, Tie1, VE-PTP, ELF-1, Ets-1, KLF2, GATA3, MMP14, Runx1, VE-cadherin, VEGFα and NGAL, except for gene and protein expression of Tie2, which was decreased in Tie2+/- mice compared to Tie2+/+ mice.
In mice, the microvasculature of the lungs is more vulnerable to angiopoietin-2 and partial deletion of Tie2 compared to those in the kidneys with respect to microvascular leakage and edema.