From the Center for Vascular Biology Research, Beth Israel Deaconess Medical Center (E.L., Z.K.Z., S.S., A.C., A.L., S.A.K.), Harvard Medical School, Boston, MA.
Department of Obstetrics and Gynecology, University Paris Est Créteil and CHI Créteil, Créteil, France (E.L., B.H.).
Hypertension. 2020 Sep;76(3):875-883. doi: 10.1161/HYPERTENSIONAHA.120.15338. Epub 2020 Jul 13.
Elevated circulating sFLT-1 (soluble fms-like tyrosine kinase) and low levels of its ligand, PlGF (placental growth factor), are key characteristics of preeclampsia. However, it is unclear if the low levels of plasma PlGF noted during preeclampsia are due to decreased placental production of PlGF or due to binding of PlGF by increased circulating sFLT-1. Here, we describe a biochemical procedure to dissociate PlGF-sFLT-1 complex ex vivo and when used in conjunction with an immunoassay platform, demonstrate a method to measure total and free PlGF in human blood samples. Using this method, we noted that plasma free PlGF levels were significantly lower in preeclampsia (N=22) than in nonhypertensive controls (N=24; mean, 314 versus 686 pg/mL, <0.05), but total PlGF levels were not different (mean, 822 versus 800 pg/mL, =0.49). In contrast, total sFLT-1 levels were significantly higher in preeclampsia than in nonhypertensive controls (mean, 16 957 versus 3029 pg/mL, <0.01) and sFLT-1 levels correlated with bound PlGF levels (bound PlGF=total PlGF-free PlGF) in these samples (=0.68). We confirmed these findings in an independent cohort of subjects (N=49). Furthermore, we did not detect any difference in PlGF mRNA by quantitative polymerase chain reaction or in PlGF protein expression by immunohistochemistry in preeclamptic placentas when compared with nonhypertensive controls. In contrast, sFLT-1 mRNA and protein levels were upregulated in placentas from women with preeclampsia. Taken together with prior studies, our results provide evidence that decrease in circulating PlGF noted during preeclampsia is largely mediated by excess circulating sFLT-1.
循环中的可溶性 fms 样酪氨酸激酶 1（sFLT-1）水平升高（可溶性 fms 样酪氨酸激酶）和其配体胎盘生长因子（PlGF）水平降低，是子痫前期的主要特征。然而，子痫前期时循环中 PlGF 水平降低是由于胎盘 PlGF 产生减少，还是由于增加的循环 sFLT-1 与 PlGF 结合所致，目前尚不清楚。在这里，我们描述了一种体外分离 PlGF-sFLT-1 复合物的生化程序，并结合免疫测定平台，展示了一种测量人血样中总 PlGF 和游离 PlGF 的方法。使用这种方法，我们注意到子痫前期患者（n=22）的血浆游离 PlGF 水平明显低于非高血压对照组（n=24；平均 314 与 686 pg/mL，<0.05），但总 PlGF 水平无差异（平均 822 与 800 pg/mL，=0.49）。相比之下，子痫前期患者的总 sFLT-1 水平明显高于非高血压对照组（平均 16957 与 3029 pg/mL，<0.01），且这些样本中的 sFLT-1 水平与结合的 PlGF 水平相关（结合 PlGF=总 PlGF-游离 PlGF；=0.68）。在另一组独立的研究对象（n=49）中，我们也得到了相同的发现。此外，与非高血压对照组相比，子痫前期胎盘的 PlGF mRNA 通过定量聚合酶链反应或 PlGF 蛋白表达通过免疫组织化学染色均未检测到差异。相反，sFLT-1 mRNA 和蛋白水平在子痫前期胎盘组织中上调。结合以往的研究，我们的结果提供了证据，表明子痫前期时循环中 PlGF 减少主要是由过量的循环 sFLT-1 介导的。
