If so, it might be possible to design preeclampsia tests and treatment.
Preeclampsia affects 3% to 5% of pregnancies. It's a leading cause of pregnancy complications and preterm birth. It occurs with onset of a sharp rise of high blood pressurehigh blood pressure and protein leakage in the urine after 20 weeks.
"This finding appears to be an important step in developing a cure for preeclampsia," says Elias Zerhouni, MD, director of the National Institutes of Health, in an NIH news release.
The NIH-funded study appears in The New England Journal of Medicine, along with a separate editorial.
It's too soon to know if the proteins cause preeclampsia, the editorialists caution. "Nevertheless, these findings are exciting," they write.
The study's researchers included Richard Levine, MD, MPH, from the National Institute of Child Health and Human Development, which is part of NIH.
Levine and colleagues studied data on 552 pregnant women, divided into five categories:
- 72 had preeclampsia before 37 weeks of pregnancy.
- 120 had preeclampsia at or after 37 weeks of pregnancy.
- 120 had gestational hypertensionhypertension (pregnancy-induced high blood pressure).
- 120 had normal blood pressure but had babies small for gestational age.
- 120 had normal blood pressure and had babies that weren't small for gestational age.
Levine's team checked the women's blood levels of two proteins: soluble endoglin and sFlt1.
Tests showed a marked rise in blood levels of those proteins two to three months prior to a preeclampsia diagnosis (the rise in sFlt1 was related to a drop in another protein, PlGF, which the researchers looked at as a ratio of sFlt1 to PlGF).
Rising levels of both endoglin and the ratio of sFlt1 to PlGF appeared to be important.
An increase in only one of the markers wasn't a strong preeclampsia predictor. But "among women with high levels of both, the risk of preeclampsia was high," the researchers write.
It might be possible to create blood tests, based on those two proteins, that predict preeclampsia, Levine's team writes.
Treatments might also follow.
"We've found specific molecules that appear to be causing the clinical signs of preeclampsia and so now we have an idea which molecules we would need to interfere with to treat the disease," Levine says, in a NICHD news release.
The editorialists aren't so sure the study proves the proteins cause preeclampsia. "The conclusions on causality seem ambitious," they write.
The editorialists included Marshall Lindheimer, MD, of the University of Chicago's departments of obstetrics, gynecology, and medicine.
"There are still unknowns," Lindheimer and colleagues write. "But we can now confidently state that a disorder once considered a mysterious disease is sufficiently understood to permit mechanistically rational studies of its prediction, diagnosis, prevention, and treatment."