Neutralization of Marinobufagenin Demonstrates Efficacy In Vitro and In Vivo in Models of Pre-Eclampsia

<b>Background/Objectives</b>: Marinobufagenin (MBG) is a biomarker that is found to be high in pre-eclampsia (preE), and thus is relevant in the pathogenesis of obstetric complications. MBG is thought to possibly be implicated in harmful signaling within cytotrophoblasts (CTBs) of the placenta. In this study, we evaluated how anti-MBG human monoclonal antibody can alter cellular signaling in CTBs and in a rat model of preE. <b>Methods</b>: CTB cell proliferation, migration, and invasion as a result of MBG, both with and without anti-MBG present, were monitored via cell-based studies. Pro-angiogenic and anti-angiogenic factors in response to MBG with and without antibody were measured. Finally, we evaluated the lead anti-MBG antibody in comparison with the parent murine antibody in a rat model of preE. <b>Results</b>: CTB cells exposed to ≥1 nM MBG showed decreased (<i>p</i> < 0.05) proliferation, migration, and invasion, decreased secretion of VEGF and PIGF, and increased secretion of sFlt-1 and sEng. Pretreatment with anti-MBG significantly (<i>p</i> < 0.05) attenuated MBG-induced CTB dysfunction and modulation of VEGF, PIGF, sFlt-1, and sEng expression. In the rat model, anti-MBG treatment normalized blood pressure, reduced proteinuria, and eliminated fetal effects. <b>Conclusions</b>: MBG is a potential causative agent for preE, as it causes dysfunction in CTBs due to anti-angiogenic milieu. Our study suggests that anti-MBG antibody binds to MBG, neutralizing it and preventing downstream signaling in vitro. In a rat model of preE, treatment with anti-MBG antibody was effective at normalizing blood pressure, kidney function, and fetal birth weights. These data suggest that a human monoclonal antibody with high specificity and affinity for MBG has potential as a therapeutic agent for preE.