Ouabain inhibits placental sFlt1 production by repressing HSP27-dependent HIF-1α pathway

Area of Science:

• Obstetrics and Gynecology
• Pharmacology
• Cell Biology

Background:

• Preeclampsia is a pregnancy disorder linked to increased placental soluble fms-like tyrosine kinase 1 (sFlt1).
• Identifying novel therapeutic targets to reduce sFlt1 is crucial for managing preeclampsia.

Purpose of the Study:

• To screen natural compounds for their ability to inhibit placental sFlt1 production.
• To investigate the underlying molecular mechanisms of sFlt1 regulation by identified compounds.

Main Methods:

• A library of 502 natural compounds was screened in human placental cell lines.
• Ouabain's effects on sFlt1 mRNA and protein expression were characterized in placental cells and explants.
• Hypoxia-inducible factor 1 (HIF-1α) and heat-shock protein 27 (HSP27) phosphorylation were assessed.
• A rat model of pregnancy-induced hypertension was used to evaluate ouabain's in vivo effects.

Main Results:

• Three cardiac glycosides (ouabain, gitoxigenin, digitoxin) inhibited sFlt1 production in vitro.
• Ouabain dose-dependently inhibited sFlt1 mRNA and protein expression.
• Ouabain reduced HIF-1α protein levels and required HSP27 phosphorylation to inhibit HIF-1α translation.
• In hypertensive rats, ouabain lowered blood pressure and increased placental HSP27 phosphorylation without adverse effects.

Conclusions:

• Ouabain effectively inhibits placental sFlt1 production via the HIF-1α/HSP27 pathway.
• Targeting this pathway presents a potential therapeutic strategy for preeclampsia.
• Further research is warranted to explore ouabain's clinical utility in managing pregnancy-induced hypertension.