INTRODUCTION: Preeclampsia (PE) is a serious complication of pregnancy characterized by poor placental establishment and placental hypoxia/ischemia, which leads to placental production of pro-inflammatory cytokines and anti-angiogenic factors such as soluble fms-like tyrosine kinase-1 (sFLT-1). However, the mechanisms regulating their production remain poorly understood.
AIM: The aim of this study was to characterize the expression of the nuclear factor of activated T-cells (NFAT) family of transcription factors (i.e. NFAT1-4) in preeclamptic placenta and determine their functional contribution to inflammatory cytokine and sFlt-1 production in primary placental cells.
METHODS: Archival preterm preeclamptic placental tissue (2 and expression of NFAT1-4 mRNA expression assessed. To determine the role of calcineurin/NFAT signaling in production of sFlt-1 and inflammatory cytokines, primary placental cells were isolated and treated with the inhibitor NFAT-calcineurin association-6 (INCA6). NFAT inhibition was assessed via inmmunofluorescent analysis of nuclear translocation, and effects on sFlt1 and inflammatory cytokines determined by ELISA and qPCR respectively.
RESULTS: mRNA expression of NFAT1-4 was not significantly altered in PE placenta relative to controls. Hypoxia significantly upregulated mRNA expression of NFAT1 (P<0.001) and NFAT3 (P<0.05) in primary human trophoblast. Inhibiting NFAT activity significantly reduced mRNA expression of FLT (P<0.001) and sflt-1 splice variant (e15a) (P<0.05), as well as mRNA expression of NFAT-dependent inflammatory cytokines such as IL-1b (P<0.01) and IL-10 (P<0.0001) in primary human trophoblast. Furthermore, inhibiting NFAT activity significantly reduced sFlt-1 protein production (P<0.05) from primary human trophoblast and explants in a dose-dependent manner.
CONCLUSIONS: In summary, we provide evidence that calcineurin-dependent NFAT proteins are hypoxia responsive and may be involved in the regulation of sFlt-1 and inflammatory cytokine production in preeclamptic placenta.