Loss of Thrombomodulin in Placental Dysfunction in Preeclampsia

OBJECTIVE: Preeclampsia is a pregnancy-specific syndrome characterized by placental dysfunction and an angiogenic imbalance. Systemically, levels of thrombomodulin, an endothelium- and syncytiotrophoblast-bound protein that regulates coagulation, inflammation, apoptosis, and tissue remodeling, are increased. We aimed to investigate placental thrombomodulin dysregulation and consequent downstream effects in the pathogenesis of preeclampsia. APPROACH AND RESULTS: Placentas from 28 preeclampsia pregnancies, 30 uncomplicated pregnancies, and 21 pregnancies complicated by growth restriction as extra controls were included. Immunohistochemical staining of thrombomodulin, caspase-3, and fibrin was performed. Placental mRNA expression of thrombomodulin, inflammatory markers, matrix metalloproteinases 2 and 9, and soluble Flt-1 were measured with quantitative polymerase chain reaction. Thrombomodulin mRNA expression was determined in vascular endothelial growth factor-transfected trophoblast cell lines. Thrombomodulin protein and mRNA expression were decreased in preeclampsia as compared with both control groups (P=0.001). Thrombomodulin mRNA expression correlated with maternal body mass index (P<0.01) and diastolic blood pressure (P<0.05) in preeclampsia. An increase in placental apoptotic cells was associated with preeclampsia (P<0.001). Thrombomodulin expression correlated positively with matrix metalloproteinase expression (P