Development of a therapeutic anti-marinobufagenin antibody

尽管子痫前期(PE)是导致母婴死亡的主要原因，但其发病机制尚不完全清楚。内源性洋地黄样强心类固醇(CTS)参与了PE的病理生理过程，临床观察表明，与CTS结合的地高辛抗体DigiBind可降低PE患者的血压。最近我们报道，在严重的PE患者中，蟾酥二烯内酯类血管收缩因子马利诺蟾毒配基(MBG)的水平增加了四倍。MBG在体内和体外均可诱导血管纤维化。由于PE中MBG水平显著升高，我们推测，在PE中，胎盘MBG水平升高可能与胎儿-胎盘循环中纤维化的发展和血管松弛障碍有关。对18例PE患者和14例正常妊娠患者进行研究。在PE患者的脐动脉中，当胎盘MBG水平升高时，我们观察到前胶原-1和胶原-1的水平增加了2倍，而转录因子和胶原合成的负调控因子Fli-1的水平降低。与对照血管相比，PE患者的脐动脉离体环对内皮素-1的反应性没有改变，对硝普钠的松弛反应明显减弱(EC_(50)=141vs.0.9nmol/L P&lt；.001)。因此，在PE中，MBG水平升高与血管纤维化和血管松弛受损有关。我们的数据显示，在PE中，当脐动脉的收缩反应没有改变时，动脉松弛机制不那么有效，这与CTS的高血压效应不仅限于血管收缩和血压本身升高，而且在没有血压升高的情况下也可能有助于心血管重构的观点一致。我们的结果进一步证明MBG是PE患者免疫中和治疗的潜在靶点。

Although preeclampsia (PE) is a major cause of maternal and fetal mortality, its pathogenesis is not fully understood. Endogenous digitalis-like cardiotonic steroids (CTS) are implicated in the pathophysiology of PE, as illustrated by clinical observations that Digibind, a digoxin antibody which binds CTS, lowers blood pressure in patients with PE. Recently we reported that plasma levels of marinobufagenin (MBG), a bufadienolide vasoconstrictor CTS, are increased four-fold in patients with severe PE. MBG induces vascular fibrosis in vivo and in vitro. Because levels of MBG in PE are markedly increased, we hypothesized that in PE, elevated placental MBG levels would be associated with development of fibrosis in feto-placental circulation, and with impairment of vascular relaxation. We studied 18 patients with PE and 14 subjects with uncomplicated pregnancy. In umbilical arteries from patients with PE, in the presence of elevated placental levels of MBG, we observed a 2-fold increase in the levels of procollagen-1 and collagen-1, and a reduced level of Fli-1, a transcription factor and a negative regulator of collagen synthesis. As compared to control vessels, isolated rings of umbilical arteries from subjects with PE, in the presence of unaltered responsiveness to endothelin-1, exhibited markedly impaired response to the relaxant effect of sodium nitroprusside (EC50= 141 vs. 0.9 nmol/L P<.001). Thus, in PE, elevated levels of MBG are associated with vascular fibrosis, and impairment of vasorelaxation. Our data showing that in PE, mechanisms of arterial relaxation are less effective in the presence of unaltered contractile responses of umbilical arteries, agree with the idea that prohypertensive effects of CTS are not limited to vasoconstriction and elevation of BP per se, but may also contribute to cardiovascular remodeling in the absence of BP elevations. Our results further demonstrate that MBG is a potential target for immunoneutralization in patients with PE.