Down-regulation of the transcription factor snail in the placentas of patients with preeclampsia and in a rat model of preeclampsia

Western blotting analysis was used for comparative expression of Snail and e- cadherin in total protein extracts. Placental cells expressing Snail and e-cadherin were identified by immunohistochemical double-labeling technique.The levels of Snail protein were decreased in human preeclamptic placentas by 30% (p < 0.01) compared to normal term, and in the rat model by 40% (p < 0.001) compared to control placentas. In preterm placentas, the levels of Snail expression varied, yet there was a strong trend toward statistical significance between preterm and preeclamptic placentas. In humans, e-cadherin protein level was 30% higher in preeclamptic (p < 0.05) placentas and similarly, but not significantly (p = 0.1), high in the preterm placentas compared to normal term. In the rat model of preeclampsia, e-cadherin was increased by 60% (p < 0.01). Immunohistochemical examination of human placentas demonstrated Snail-positive staining in the nuclei of the villous trophoblasts and mesenchymal cells and in the invasive trophoblasts of the decidua. In the rat placenta, the majority of Snail positive cells were spongiotrophoblasts of the junctional zone, while in the labyrinth, Snail-positive sinusoidal giant trophoblasts cells were found in some focal areas located close to the junctional zone.We demonstrated that human preeclampsia and the salt-induced rat model of preeclampsia are associated with the reduced levels of Snail protein in placenta. Down-regulation of the transcription factor Snail in placental progenitor cell lineages, either by intrinsic defects and/or by extrinsic and maternal factors, may affect normal placenta development and function and thus contribute to the pathology of preeclampsia.Preeclampsia, a devastating, life-threatening, human pregnancy complication, develops in 3-10% of pregnancies. Clinical symptoms include a sudden onset of hypertension accompanied by proteinuria, edema and often fetal growth restriction [1]. The placenta of patients with preecl