UAB Researchers Uncover "Residency Switch" in Uterine Immune Cells, Linking NFAT Pathway to Preeclampsia and Placental Development

UAB researchers identify a "residency switch" in uterine immune cells that is essential for placental blood flow, shedding new light on the causes of preeclampsia.

By: AXL Media

Published: Mar 13, 2026, 6:50 AM EDT

Source: Information for this report was sourced from University of Alabama at Birmingham

The Critical Role of Uterine Natural Killer Cells

Successful early pregnancy relies on a precise biological "landing" where the embryo connects with the mother’s blood supply. This coordination is steered by specialized uterine natural killer (uNK) cells, which are responsible for guiding placental development and remodeling maternal vessels. New research published in Science Translational Medicine reveals that this guidance work is governed by an immune switch called NFAT. When this pathway is active, uNK cells successfully take up residence in the uterus. However, when the signal is diminished, fewer cells remain in the uterine lining, potentially leading to inadequate blood flow to the placenta and subsequent pregnancy complications.

A Discovery Beyond Transplant Immunology

While the study was led by Dr. Paige Porrett and her team in the context of uterus transplantation, the biological implications extend to all pregnancies. Using transplant recipients as a "lens" allowed researchers to observe the uterine immune environment with unprecedented clarity. The team discovered that the NFAT switch—previously only understood for its role in T cells—is a fundamental component of human placental development. This finding offers a new mechanical explanation for conditions like preeclampsia, implantation failure, and early pregnancy loss, which affect a broad range of patients beyond the immunocompromised population.

Visualizing the Invisible via Single-Cell Sequencing

To identify this hidden circuit, the UAB team utilized single-cell RNA sequencing, a high-resolution technology that measures gene activity in individual cells. Traditional research methods often struggle to capture the highly dynamic shifts within uterine tissue, but this granular approach allowed the team to see gene programs changing across thousands of individual cells. "You need that granularity to identify a pathway like this," noted Dr. Porrett. This technology made it possible to confirm that the NFAT pathway, which had previously only been observed in mouse models, is actively controlling tissue residency in human pregnancies.