TNF‐α from monocyte of patients with pre‐eclampsia‐induced apoptosis in human trophoblast cell line

OBJECTIVE: In pre-eclampsia, fetal growth restriction is frequently observed, and the possible involvement of inhibitory substances on trophoblast cell proliferation and differentiation has been suggested. The objective of this study was to investigate the effects humoral factors, such as cytokines, produced in immune cells on proliferation of an immortalized trophoblastic cell line (TCL) that we established. METHODS: Serum and lymphocyte layers were isolated from the blood of normal pregnant and preeclamptic women. The lymphocyte layer was further fractionated into different immune cell populations by the Stem Sep method. Immortalized trophoblastic cells were cultured with the sera diluted. The cytokine concentrations in the supernatants of lymphocyte cultures were compared between normal pregnancy and pre-eclampsia. The number, DNA content and induced apoptosis were examined on the immortalized trophoblastic cells at the end of culture. RESULTS: The sera from preeclamptic women significantly inhibited the immortalized trophoblastic cell proliferation in comparison with those from normal pregnancy. Among the lymphocyte fractions, monocytes significantly inhibited the immortalized trophoblastic cell proliferation. The monocytes from preeclamptic women were found to produce higher levels of tumor necrosis factor-alpha (TNF-alpha) in the culture supernatant than those from normal pregnant women. The coculture with the monocytes from preeclamptic women increased the frequency of TUNEL-positive TCL cells. TNF-alpha inhibited immortalized trophoblastic cell proliferation in a dose-dependent manner and induced apoptosis. CONCLUSION: The present results suggest that monocytes are activated and that cytokines, such as TNF-alpha, which is produced by monocytes, induce apoptosis and inhibit proliferation of trophoblast cells in pre-eclampsia.