Baboon placental heparin-binding epidermal growth factor-like growth factor

Area of Science:

• Reproductive biology
• Developmental biology
• Endocrinology

Background:

• Placental extravillous trophoblast (EVT) remodeling of uterine spiral arteries is crucial for adequate fetoplacental blood flow.
• Heparin-binding EGF-like growth factor (HB-EGF) promotes EVT differentiation and invasion in vitro.
• Reduced maternal HB-EGF is observed in preeclampsia, but its role in early placental insufficiency is unclear.

Purpose of the Study:

• To investigate the effect of prematurely elevated estrogen on placental HB-EGF expression and uterine spiral artery remodeling in a nonhuman primate model.
• To determine if early estrogen exposure contributes to placental insufficiency by altering HB-EGF levels.

Main Methods:

• A baboon model was used where estrogen (estradiol, E2) was administered daily from days 25-59 of gestation (term=184 days).
• Uterine spiral artery remodeling was assessed on day 60 by measuring the percentage of vessel remodeling.
• Placental HB-EGF, amphiregulin (AREG), and EGF expression were quantified using immunocytochemistry and image analysis.

Main Results:

• Estradiol treatment significantly reduced spiral artery remodeling across all measured vessel diameters (90%, 84%, 70% reduction for 26-50, 51-100, >100 µm respectively; P < 0.01).
• Placental HB-EGF protein levels were decreased threefold (P < 0.01) in E2-treated baboons compared to controls.
• Expression of AREG and EGF in the placenta remained unaltered by E2 treatment.

Conclusions:

• Prematurely elevated estrogen in early baboon pregnancy suppresses uterine spiral artery remodeling.
• HB-EGF is downregulated by early estrogen exposure, suggesting a role in mediating estrogen's effects on EVT-driven vascular remodeling.
• These findings propose that HB-EGF modulates estrogen-sensitive spiral artery remodeling by EVTs in early pregnancy.