Abstract
Normal pregnancy is associated with uterine and vascular remodeling by matrix metalloproteinases (MMPs) to facilitate placental blood flow and uterine expansion for the growing fetus. Increases in MMP-2 and MMP-9 in response to estrogen and progesterone promote placentation, uteroplacental vascularization and fetal growth during healthy pregnancy, but are altered in preeclampsia (PE). PE is characterized by hypertension in pregnancy (HTN-Preg) and fetal growth restriction (FGR). Predisposing genetic, demographic and environmental factors alter uteroplacental MMPs, immune response and integrins leading to apoptosis of invasive trophoblasts, inadequate spiral arteries remodeling, and reduced uteroplacental perfusion pressure (RUPP). Ensuing placental ischemia causes imbalance between anti-angiogenic soluble fms-like tyrosine kinase-1 (sFlt-1) and pro-angiogenic placental growth factor (PlGF) and promotes the release of tumor necrosis factor-α (TNF-α), hypoxia-inducible factor, reactive oxygen species, and angiotensin AT(1) receptor agonistic autoantibodies. Systemically, these bioactive factors target vascular endothelial cells, smooth muscle cells, and extracellular matrix, causing endothelial dysfunction, vasoconstriction, inadequate vascular remodeling, and HTN-Preg, while locally they diminish uteroplacental remodeling and cause FGR. In support, animal models of HTN-Preg induced by RUPP or infusion of sFlt-1 or TNF-α show decreases in vascular MMP-2, MMP-9 and vasodilation, increases in MMP-1, MMP-7 and vasoconstriction, collagen accumulation, and arterial stiffness. Also, decreases in uterine MMP-2 and MMP-9 could impede uterine expansion and lead to preterm birth. Conversely, PlGF and TNF-α antagonist reversed MMPs imbalance and collagen accumulation, and improved vascular function, blood pressure, and pup weight in HTN-Preg models. Persistent postpartum changes in MMPs could affect maternal hemorrhage, future pregnancies, and HTN, and cause fetal programming of cardiovascular and metabolic diseases. Understanding the aberrant uteroplacental and vascular signaling and remodeling by MMPs could help design new biomarkers and remedies for PE. Targeting bioactive factors and rectifying MMP imbalance could improve vascular and uteroplacental remodeling, and manage HTN-Preg, FGR and PE.