Researchers discover what may be the root cause of preeclampsia, and how to fix it

Preeclampsia is a life-threatening pregnancy complication that affects roughly one in ten pregnancies worldwide and, in the United States alone, around 5-8% of pregnancies.

The condition can lead to severe, long term health consequences for mothers and their babies.

Despite its prevalence, though, the underlying cause has remained largely unknown.

But now, after years of research, a team led by Johann Gudjonsson, M.D., Ph.D., and Olesya Plazyo, M.S., Ph.D., together with a large multidisciplinary group of scientists, has identified a key molecular driver of preeclampsia, and demonstrated a potential way to counteract it in both mouse models and human placental tissue.

In addition, their discovery has revealed new findings regarding female-biased systemic autoimmunity and its link to preeclampsia.

Using advanced single-cell and spatial RNA sequencing of human placentas, coupled with in vitro, in vivo and ex vivo experimental models, the group discovered that VGLL3, a transcription co-regulator in the Hippo signaling pathway, is notably elevated in preeclamptic placentas.

Elevated VGLL3 was shown to drive immune activation, disrupt trophoblast differentiation, and impair blood vessel function, processes that contribute to high blood pressure, restricted fetal growth and an increased risk of infant mortality.

Strikingly, when the team targeted VGLL3, either by deleting the gene in mouse placentas or by modulating the Hippo signaling in human placenta samples from mothers with preeclampsia, they were able to prevent or reverse key features of preeclampsia without affecting maternal or fetal health.

These findings position VGLL3 as a promising new treatment pathway for preeclampsia.

The study is published in Circulation.

A chance conversation leads to a major discovery

The research, which was recently published in Circulation, began over seven years ago when Gudjonsson’s team was examining skin data sets and identified the transcriptional coregulator called VGLL3.

At the time, the researchers observed that VGLL3 was expressed in both female and male skin, but displayed a pronounced sex bias, with higher expression in female skin cells.

VGLL3 was also strongly upregulated in the skin of patients with lupus and systemic sclerosis, both female-biased autoimmune diseases that are associated with an increased risk of preeclampsia, suggesting a potential role in autoimmune risk and disease pathogenesis.

Digging into the literature, the team found that VGLL3 had been linked to the timing of sexual maturity in Atlantic salmon, and the onset of menstruation in women.

Notably, among all human organs, VGLL3 shows its highest expression in the placenta, an organ that plays a central role in regulating immunity during pregnancy by establishing immune tolerance while maintaining robust innate immune defenses to protect the mother and fetus from bacteria.

The connection to preeclampsia emerged unexpectedly during a brief hallway conversation at the University of Michigan.

While speaking with a colleague in obstetrics and gynecology, Gudjonsson learned that distinguishing preeclampsia from lupus in pregnant patients can be clinically challenging because the symptoms often overlap.

“Typically, it’s only after delivery that the diagnosis becomes clear,” Gudjonsson said. “That’s what sparked our interest in looking at VGLL3 in preeclampsia.”

“Preeclampsia causes intergenerational harm – people with a history of preeclampsia are more likely to develop heart failure, strokes, chronic kidney disease, and dementia over their lifetimes than those without such a history,” explained Ashley Hesson, M.D., Ph.D., an author on the paper and the Associate Director of the Cardio-Obstetrics Program in the Department of Obstetrics & Gynecology at U-M and who also has experienced preeclampsia herself.

“Their infants are also more likely to be born premature, which carries its own complications.”

Inspired, the team hit the ground running, collecting an enormous amount of data and creating multiple mouse models, turning the VGLL3 gene on and off to see what factors it related to in the pathological processes happening in preeclamptic human placentas.

“We found that VGLL3 drives abnormal blood vessel development, which is a hallmark of preeclampsia. It also activates inflammatory pathways, alters trophoblast differentiation and contributes to extracellular matrix abnormalities including fibrosis seen in patients.”

In pregnant mice, the team found that the overexpression of VGLL3 led to elevated blood pressure, while deleting the gene allowed for completely normal pregnancies.

The team then tested the same hypothesis in human placental biopsies from patients with preeclampsia.

“We targeted VGLL3 in these placentas and found we were able to normalize, or even reverse, features of preeclampsia,” Gudjonsson said. “That was remarkably consistent with what we saw in the mice.”

The findings suggest that VGLL3 acts as a disease amplifier, intensifying pathological processes in women who develop preeclampsia.

Importantly, the gene does not appear to be required for healthy pregnancy.

“That means it could potentially be safely targeted,” Gudjonsson noted.

Researchers believe that under normal conditions VGLL3 may confer an evolutionary advantage, fine-tuning an immune response to support the mother and baby.

When overexpressed or dysregulated, however, the same mechanism becomes harmful. In fact, VGLL3 is a master regulator of gene transcription and impacts immune regulation across multiple systems.

The team discovered that VGLL3 plays a role in growth, angiogenesis, leukocyte-mediated immunity and cell differentiation.

Plazyo adds that the work required building a large single-cell RNA sequencing resource, reflecting the substantial effort behind the discovery.

The findings have also helped to unify what was previously thought to be distinct features of preeclampsia.

“We’ve long known preeclampsia is a syndrome,” she explained.

“Some placentas show prominent vascular defects, others inflammation, and others extracellular matrix dysregulation and fibrosis. What we’re seeing now is that VGLL3 drives all of these processes, connecting them into a single mechanistic pathway that no one has recognized before.”

It’s a reminder of how science often unfolds, Plazyo adds, noting how sometimes following an observation can lead you somewhere “completely unexpected.”

“It is through rigorous, collaborative science that we can make a meaningful difference in the diagnostic and therapeutic options available for people affected by preeclampsia, potentially improving pregnancy outcomes and reducing the lifelong cardiovascular risks conferred by this disease” said Hesson.

What could be next for treating preeclampsia

By integrating human placental data with rigorous experimental models, the team was able to move beyond association to mechanism notes Santhi Ganesh, M.D., an author on the paper.

“This is exactly what is needed to translate discoveries like this into meaningful advances for patients,” said Ganesh, who is also the Associate Chief of Cardiovascular Medicine at U-M.

Prior to this discovery, the FLT1 gene had been linked to preeclampsia, however, studies showed that deleting FLT1 disrupted normal placental development and was lethal in pregnancy.

In contrast, targeted VGLL3, while upstream of dysregulated FLT1 expression, produced the opposite effect, protecting against disease without compromising the health of the mother or baby.

“This represents a novel pathway and a previously unrecognized mechanism,” said Gudjonsson.

“All of our data suggests that VGLL3 is either a central driver or a major contributor to preeclampsia and may indeed play an important role in immune regulation beyond preeclampsia.”

Gudjonsson and Plazyo believe their findings open the door to a new therapeutic strategy and plan to further explore how VGLL3 or its downstream signaling pathways might be safely targeted.

Their long term goal is to translate this work into real-world treatments that could improve outcomes for mothers and babies affected by preeclampsia.

“What’s exciting is that this pathway drives disease, connecting abnormal blood vessel growth, inflammation, and fibrosis, yet isn’t needed for a healthy pregnancy, which is exactly what you want in a potential treatment target.”

Paper cited: “Defective Trophoblast Differentiation, Endothelial Dysfunction, and Immune Dysregulation in Preeclampsia Coalesce on a Placental VGLL3-Centered Gene Network,” Circulation. DOI: 10.1161/CIRCULATIONAHA.125.076218

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