Marinobufagenin as a Target for DIGIBIND in Preeclampsia

Preeclampsia (PE) complicates from 5 to 10% of pregnancies and it is a number one cause of maternal and fetal morbidity and mortality worldwide. Nevertheless, a specific and highly effective therapy of this disorder does not exist. As illustrated by therapeutic efficacy of anti-digoxin antibody (DIGIBIND) in preeclampsia, endogenous digitalis-like sodium pump ligands play an important role in the pathogenesis of this syndrome. Previously, we demonstrated that levels of endogenous bufadienolide Na/KATPase inhibitors are elevated in patients with PE, and that antibody to marinobufagenin lower blood pressure in rats with pregnancy-induced hypertension and ex vivo reverse inhibition of the Na/K-ATPase from erythrocytes from patients with PE. Most recently, we developed three anti-MBG monoclonal antibodies which in lower blood pressure in several rat experimental models. We are proposing a pilot proof-of concept study aimed to demonstrate that MBG is target for DIGIBIND in preeclampsia. If successful, this trial will provide basis for the development of a clinically-usable anti-MBG monoclonal antibody. We hypothesize that in patients with preeclampsia DIGIBIND induces vasorelaxation due to blockade of circulating MBG. The specific aims of the study are to demonstrate that isolated perfused preeclamptic placentae ex vivo release MBG at concentration sufficient to induce vasoconstriction that DIGIBIND reverses vasoconstriction induced by placental perfusate, and that vasorelaxant effect of DIGIBIND is due to blockade of MBG. The study population will be pregnant women (18-50 years), 34-39 weeks of fetal gestational age with preeclampsia The primary outcome of the study variable will be the difference in the vascular tone in isolated perfused cotyledons. The secondary outcomes will be: (i) the degree of MBG binding to DIGIBIND at different time points following DIGIBIND administration, (ii) the effect of DIGIBIND on the activity of Na/K-ATPase in erythrocytes, and (iii) the ex vivo effect of DIGIBIND on the vascular tone in the isolated placental lobes.