Increased expression of sFlt-1 in in vivo and in vitro models of human placental hypoxia is mediated by HIF-1

Ori Nevo, Nima Soleymanlou, Yuan Wu, Jing Xu, John Kingdom, Ariel Many, Stacy Zamudio, Isabella Caniggia

Research output: Contribution to journalArticlepeer-review


Elevated expression of soluble vascular endothelial growth factor receptor-1 (sFlt-1) in preeclampsia plays a major role in the pathogenesis of this serious disorder of human pregnancy. Although reduced placental oxygenation is thought to be involved in the pathogenesis of preeclampsia, it is unclear how oxygen regulates placental sFlt-1 expression. The aims herein were to investigate sFlt-1 expression in in vivo and in vitro physiological and pathological models of human placental hypoxia and to understand the role of hypoxia inducible factor-1 (HIF-1) in regulating the expression of this molecule. sFlt-1 expression in placental villi was significantly increased under physiological low oxygen conditions in early first-trimester and in high-altitude placentae, as well as in pathological low oxygen conditions, such as preeclampsia. In high-altitude and in preeclamptic tissue, sFlt-1 localized within villi to perivascular regions, the syncytiotrophoblast layer, and syncytial knots. In first-trimester villous explants, low oxygen, but not hypoxia-reoxygenation (HR), increased sFlt-1 expression. Moreover, exposure of villous explants to dimethyloxalyl-glycin, a pharmacological inhibitor of prolyl-hydroxylases, which mimics hypoxia by increasing HIF-1α stability, increased sFlt-1 expression. Conversely, HIF-1α knockdown using antisense oligonucleotides, decreased sFlt-1 expression. In conclusion, placental sFlt-1 expression is increased by both physiologically and pathologically low levels of oxygen. This oxygen-induced effect is mediated via the transcription factor HIF-1. Low oxygen levels, as opposed to intermittent oxygen tension (HR) changes, play an important role in regulating sFlt-1 expression in the developing human placenta and hence may contribute to the development of preeclampsia.

Original languageEnglish
Pages (from-to)R1085-R1093
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number4
StatePublished - 2006
Externally publishedYes


  • High altitude
  • Hypoxia
  • Hypoxia-reoxygenation
  • Preeclampsia


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