Differential Expression of Vascular Endothelial Growth Factor (VEGF), Endocrine Gland Derived-VEGF, and VEGF Receptors in Human Placentas from Normal and Preeclamptic Pregnancies

Abstract

Vascular endothelial growth factor (VEGF) is a potent regulator of placental vascular function. Endothelial dysfunction is a key factor associated with preeclampsia. In this study, we examined expression of VEGF, endocrine gland-derived VEGF (EG-VEGF), VEGF receptors 1 and 2 (VEGFR-1 and VEGFR-2), and neuropilin-1 and -2 (NP-1 and NP-2) in human placentas from women with normal and preeclamptic (PE) pregnancies using quantitative or semiquantitative PCR. We found that total VEGF mRNA expression was increased 2.8-fold (P < 0.05), along with increases in mRNA expression of VEGF121, 165, and 189 (P < 0.05; 1.7-, 1.9-, and 1.8-fold, respectively) in PE vs. normal placentas. Expression of VEGFR-1 mRNA, but not EG-VEGF and the other three VEGF receptors studied, was elevated (P < 0.05) 2.7-fold in PE vs. normal placentas. Protein expression of VEGF and its four receptors was determined using Western blot analysis. For VEGF, two major isoforms (VEGF165 and 189) were detected. For VEGFR-1, VEGFR-2, NP-1, and NP-2, one major band was observed at 180, 235, 130, and 130 kDa, respectively. All of these bands were corresponding to their positive controls. Of these five proteins studied, only VEGFR-1 levels were increased (P < 0.05; 1.7-fold) in PE placentas. The expression of VEGF and the four VEGF receptors was confirmed using immunohistochemistry. They were primarily present in syncytiotrophoblasts and endothelial cells of villous capillaries and large vessels. Thus, together with previous reports that VEGFR-1 mediates trophoblast function and inhibits VEGF-induced angiogenesis and endothelium-dependent vasodilation, these data suggest that the increased VEGFR-1 expression may alter VEGF- mediated function on trophoblast and endothelial cells in PE placentas.

Protein Expression of Aryl Hydrocarbon Receptors in Human Placentas from Mild Preeclamptic and Early Pregnancies

“…Term placentas were obtained immediately after cesarean section delivery from women with N (n = 14) and mPE (n = 10) pregnancies as described [[12], [13]]. The first trimester placentas (n = 12) were obtained from women with induced abortion at gestation time of 6-8 weeks.…”

“…Immunolocalization of AhR in placental tissues was visualized by indirect observation via the avidin:biotinylated-peroxidase complex method (Vector Laboratories, Burlingame, CA) as described [[12], [13]]. Tissue sections (5 μm thick) were deparaffinized and dehydrated, followed by incubating the sections in a 10 mM citrate buffer solution (pH 6.0) in a microwave for 10 min for antigen retrieval.…”

“…Western blotting was carried out as described [ [12], [13]]. Placental tissues were pulverized in liquid nitrogen using a mortar and pestle, followed by prepared in RIPA lysis buffer (50 mM HEPES, 0.1 M NaCl, 10 mM EDTA, 4 mM sodium pyrophosphate, 10 mM sodium fluoride, 2 mM sodium orthovanadate [pH 7.5]; 1 mM phenyl methyl sulfonyl fluoride [PMSF], 1% Triton X-100, 5 µg/ml leupeptin, 5 µg/ml aprotinin), and further lyzsed by sonication.…”

Placental Angiogenesis and Fetal Growth Restriction

“…PlGF shares biochemical and functional features with VEGF and interacts with VEGFR-1 (Flt-1). PlGF and VEGF-A have synergistic effects regarding angiogenesis, but vessels induced by PlGF are more mature and stable than vessels induced byVEGF-A [Chung et al, 2004]. PlGF is abundantly expressed in the human placenta.…”

The gonadotropins: Tissue-specific angiogenic factors?

“…Thus, several groups observed elevated concentration of VEGFR-1 protein in the syncytiotrophoblast from patients with preeclampsia (Helske et al, 2003;Chung et al, 2004), while VEGF protein concentrations seemed to decrease (Ahmad et al, 2004;Chung et al, 2004) Nevertheless, a direct correlation between elevated hCG and VEGF serum concentration in the patients serum could not be established up to now (Bartha et a., 2003). In contrast to hCG, FSH and LH do not seem to be not involved in preeclamptic processes.…”