Development of a therapeutic anti-marinobufagenin antibody

虽然先兆子痫（PE）是孕产妇和胎儿死亡的主要原因，但其发病机制尚未完全了解。内源性洋地黄样强心类固醇（CTS）与PE的病理生理学有关，如临床观察结果所示，Digibind（一种结合CTS的地高辛抗体）可降低PE患者的血压。最近，我们报道了严重PE患者血浆中蟾毒配基（MBG）（一种蟾毒类血管收缩剂CTS）的水平增加了4倍。 MBG在体内和体外诱导血管纤维化。由于PE中MBG水平显著升高，我们假设PE中胎盘MBG水平升高与胎儿-胎盘循环中纤维化的发展以及血管舒张受损相关。我们研究了18例PE患者和14例无并发症妊娠患者。在PE患者的脐动脉中，在存在升高的胎盘MBG水平的情况下，我们观察到前胶原-1和胶原-1的水平增加2倍，并且Fli-1的水平降低，Fli-1是一种转录因子和胶原合成的负调节因子。与对照血管相比，在对内皮素-1的反应性不变的情况下，PE受试者的脐动脉离体环对硝普钠的舒张作用表现出明显受损的反应（EC 50 = 141 vs. 0.9 nmol/L P<.001）。因此，在PE中，MBG水平升高与血管纤维化和血管舒张受损相关。我们的数据表明，在PE中，动脉舒张机制在脐动脉收缩反应不变的情况下效果较差，这与CTS的促高血压作用不仅限于血管收缩和血压升高本身的观点一致，而且可能在血压升高的情况下也有助于心血管重塑。我们的研究结果进一步表明，MBG是PE患者免疫中和的潜在靶点。

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.