Modulation of placental vascular endothelial growth factor by leptin and hCG

Abstract

Vascular endothelial growth factor (VEGF) has been identified as an endothelium-specific mitogen and inducer of angiogenesis and endothelial cell survival. Leptin and hCG have also been suggested as possible regulators of angiogenesis in various models. In-vivo and in-vitro assays revealed that leptin has an angiogenic activity and that the vascular endothelium is a target for leptin. Thus, we hypothesized that products of cytotrophoblastic cells may play a role in placental angiogenesis and we therefore investigated the effects of leptin and hCG on cytotrophoblast VEGF secretion. We incubated cytotrophoblastic cells (CTB) with recombinant human leptin (rhLept) (0-4 pg/ml) or hCG (0-30 000 IU/ml) for 4 h. rhLept significantly stimulated hCG (P = 0.0045) and decreased VEGF release (P = 0.0008) by CTB in a concentration-dependent manner. On the other hand, increasing concentrations of hCG (0-30 000 IU/ml), induced a significant inhibition of leptin secretion (P = 0.0028) and a marked dose-dependent stimulation of VEGF165 secretion (P < 0.0001). We observed an increase of >1000-fold in basal trophoblastic VEGF secretion with physiological concentrations of hCG in vitro. An inhibitory effect of hCG on trophoblastic leptin secretion was also observed, suggesting that hCG might exert a possible negative feedback on trophoblastic release of leptin. We hypothesize that trophoblastic products such as hCG and leptin are probably involved in the control of VEGF secretion at the maternal-fetal interface.