Dissociation between increased apoptosis and expression of the tumor necrosis factor-alpha system in term placental villi with preeclampsia

To analyse in situ the placental expression of tumor necrosis factor-α (TNF-α), its receptors TNFRp55 and TNFRp75, and apoptosis in normotensive and preeclamptic pregnancies. We simultaneously analyzed the immunostaining of TNF-α, its receptors and apoptosis in term placentas of 15 patients with preeclampsia and 15 normotensive pregnant women as controls. In normotensive villi TNF-α and TNFRp75 were expressed more in syncytiotrophoblasts than cytotrophoblasts or stromal cells, and were almost absent in endothelial cells. TNFRp55 was expressed uniformly in all types of placental cells. Apoptosis was more marked in syncytiotrophoblasts than cytotrophoblasts. In preeclamptic trophoblasts apoptosis was exaggerated whereas expression of TNF-α and its receptors remained unchanged. Placental expression of TNF-α and TNFRp75 appear inter-adaptative and follow the same pattern, whereas TNFRp55 and TNF-α appear independent. In addition, the exaggerated apoptosis of preeclamptic trophoblasts may be dependent on factors other than the TNF-α system alone.