Anti-angiogenic factors, such as sFlt1 [soluble Flt1
(fms-like tyrosine kinase 1)] and soluble endoglin
(sEng), inhibit angiogenesis and promote vascular
dysfunction. sFlt-1 binds to VEGF and PlGF, and sEng
impairs binding of TGF-β1 to its receptor, blocking
their actions.68,69 Both of them are expressed by normal
placenta.70,71 Many studies have amplified the theory
of the misbalance of circulating angiogenic factors in PE and the sFlt-1/PlGF ratio has been proposed as
an additional diagnostic or predictive tool for PE.72-74
A meta-analysis showed increased concentrations of
placental and maternal sFlt1 and sEng and decreased
concentrations of PIGF in pregnancies which developed
PE. VEGF was lower, though not significantly
different, between the women who developed PE and
those who did not.