Abstract P426: Novel Peptide B7-33 Demonstrates Efficacy In Rat Models Of Preeclampsia

Background: Preeclampsia (PreE) is a hypertensive pregnancy disorder, which occurs in approximately 10% of all gestations. The literature suggests potential therapeutic role of H2 relaxin in PreE. Due to the complex insulin-like structure of relaxin (A- and B- chains, 53 amino acids, 3 disulfide bonds), a novel H2 relaxin B-chain-only peptide variant B7-33 (27 amino acids without any disulfide bonds) has recently been developed. Objective: This single-chain peptide displayed equivalent efficacy to the natural H2 relaxin in several functional assays both in vitro and in vivo . The Aim of this study is to evaluate whether B7-33 attenuates preE syndrome in rat models of PreE. Methods: Rat Model 1. The efficacy of B7-33 was evaluated in the Reduction of Uterine Perfusion Pressure (RUPP) model as described previously. RUPP rats are randomly assigned to 4 groups (N=8/group): 1) vehicle, 2) B733; 3) B733-Fc; and 4) B733-HSA. Rats are dosed twice weekly (i.v.) from GD10 to GD 20. Rat Model 2. Timed-pregnant rats are used, and the model is conducted as previously described. DOCA and saline administration begin at approximately GD2. Three groups of animals are studied (n=8 per group). 1) normal pregnant rats; 2) pregnant animals injected (i.p.) initially with 12.5 mg of DOCA, followed by a weekly injection of 6.5 mg, and whose drinking water was replaced with 0.9% saline; 3) rats administered DOCA and saline as for Group 2, and given B733 35 ug i.p. biweekly from GD10-20. BP, proteinuria and inflammatory markers were evaluated. Statistical comparisons were performed using analysis of variance with Duncan’s post hoc test. Results: RUPP rats have increased MAP, plasma TNF-α, and plasma sFlt-1 along with decreased NO index compared to normal pregnancy. Treatment with B733 and B7-33 fusion proteins lowers MAP, TNF-α, and sFlt-1 back to that of normal pregnancy. B7-33 data are consistent with earlier data with serelaxin in the RUPP model. All fusions tested ameliorate hypertension in the RUPP animals. B7-33 normalizes BP and proteinuria in the DOCA rat model of preE. Conclusion: Both B7-33 and B7-33 fusion proteins attenuate preE syndrome in RUPP and DOCA rat models of PreE. We conclude that B7-33 is an ideal candidate for development as a novel therapeutic in preE.