Preeclampsia affects 3-5% of pregnancies, contributes to 10-15% of maternal mortality, and is a leading cause of prematurity and increased long-term morbidity in those affected. Contemporary understanding of preeclampsia's maternal-fetal interface suggests a major role for placental oxidative stress resulting from ischemia-reperfusion injury. We hypothesized the pregnancy hormone relaxin would reduce cytotrophoblast apoptosis, necrosis (aponecrosis) and export of placental debris into maternal circulation. If so, relaxin might be employed as a therapeutic intervention to diminish activation of the maternal systemic inflammatory response central to clinical disease development. HTR-8/SVneo cells, a model for first trimester extravillous trophoblast, were subjected to serum deprivation and hypoxia or hypoxia-reoxygenation. The cells were treated with recombinant human relaxin or vehicle (VEH), and apoptosis and/or necrosis evaluated by terminal deoxynucleotidyl transferase mediated dUTP nick endlLabeling (TUNEL), CellEvent® Caspase-3/7 + SYTOX® AAdvance™, and propidium iodide staining determined by fluorescent microscopy or flow cytometry. To interrogate mechanisms of relaxin cytoprotection, HTR-8/SVneo cells were pre-treated with pharmacological inhibitors of PI3-kinase LY294004, Akt/PKB MK2206, or DMSO vehicle. Serum deprivation and hypoxia increased apoptotic cell death in HTR-8/SVneo cells, which was significantly ameliorated by concurrent relaxin treatment. Serum deprivation and hypoxia-reoxygenation increased necrotic cell death in HTR-8/SVneo cells, which was also significantly rescued by concurrent relaxin treatment. Pretreatment with LY294002 or MK2206 significantly blunted relaxin's cytoprotective effect. We demonstrated trophoblast cytoprotection by intervention with supraphysiologic relaxin concentrations, a process mediated through the PI3 kinase-AKT/PKB cell survival pathway. This provides further rationale for clinical investigation of relaxin as a potential preeclampsia therapeutic.
- H2 relaxin
- HTR-8/SVneo cell
- apoptosis and necrosis
- Copyright © 2016, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology