Abstract P3042: Novel Peptide B7-33 and It's Lipidated Derivative Protect Cytotrophoblasts From Preeclampsia Phenotype in a Cellular Model of the Syndrome

Abstract

Background: Preeclampsia (PreE) is a pregnancy disorder characterized by new onset of hypertension and reduced fetal weight. We have previously shown that marinobufagenin (MBG) and hyperglycemia impairs cytotrophoblasts (CTBs) function. The potential therapeutic role of H2 relaxin in PreE was reported, a novel H2 relaxin B-chain-only peptide B7-33 and its lipidated derivative have recently been developed. This study evaluates whether B7-33 and its lipidated derivative improve CTBs function and preE phenotype. Methods: A palmitic acid was attached at the N-terminus of B7-33. Human CTBs were treated with DMSO (vehicle) or 0.1, 1, 10 or 100 nM of MBG or with 100, 150, 200, 300, or 400 mg/dL glucose for 48h and were co-treated either with B7-33 (25 nM) or its lipidated derivative (25 nM) in the presence and absence of either MBG or hyperglycemia exposure. Some cells were pretreated with relaxin antagonist (1.0 μM RXFP1) prior to MBG or hyperglycemia exposure. Levels of vascular endothelial growth factor (VEGF), placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) were measured in culture media using ELISA kits. Statistical comparisons were performed using analysis of variance with Duncan’s post hoc test. Results: Lipidation of B7-33 results in a significant increase of half-life of B7-33 without altering its activity. Secretion of sFlt-1 was increased while VEGF and PIGF were decreased in CTBs treated with ≥1.0 nM MBG and ≥150 mg/dl of glucose (*p < 0.05 for each). Co-treatment with B7-33 (25 nM) and its lapidated derivative (25 nM) rescued CTBs from either MBG-induced and hyperglycemia-induced anti-angiogenic profile (p < 0.05 for each). B7-33 and its lapidated derivative cause an increase in the expression of VEGF in CTBs, however, they have no effect on other factors. The B7-33-induced upregulation of VEGF expression is attenuated by 1.0 μM RXFP1 antagonist. Conclusion: Both B7-33 and its lipidated derivative mitigate the MBG- and hyperglycemia-induced dysfunction of CTBs by attenuating anti-angiogenic phenotype similar to that seen in preE. Moreover, the B7-33 and its lipidated derivative induced effect on CTBs are attenuated by a relaxin antagonist. The preclinical study with B7-33 and its lipidated derivative are now underway.