Regulatory T Cell Dynamics in Maternal-Fetal Immunity

The maternal immune system must tolerate a semiallogeneic foetus while preserving defence against pathogens. Regulatory T cells (Tregs), marked by expression of FOXP3 and CD25, accumulate in the decidua and peripheral blood during early gestation, where they suppress effector responses and promote placental development. Their expansion and functional competence are modulated by pregnancy hormones such as progesterone and oestrogen, and by interactions with trophoblasts via immune‐checkpoint molecules including PD-1/PD-L1 and CTLA-4. Dynamically, Treg populations exhibit clonal expansion at the uterine interface, contributing to feto-maternal tolerance. Dysregulation of Treg numbers or suppressive capacity is associated with adverse outcomes such as miscarriage, pre-eclampsia and hypertensive disorders of pregnancy. Recent work has begun to unravel the molecular signals that govern Treg trafficking, antigen specificity and intercellular crosstalk with decidual macrophages, natural killer cells and dendritic cells. These insights are informing novel therapeutic strategies aimed at restoring immune tolerance in complicated pregnancies.

Research from Nature Portfolio

Alterations of the PD-1/PD-L1 immune checkpoint at the maternal-foetal interface have been shown to underlie pre-eclamptic pathology through disruption of regulatory T cell–Th17 balance. In a pre-eclamptic rat model, reduced expression of PD-1 and its ligand led to diminished Treg frequencies and heightened inflammatory effector responses. Administration of a PD-L1 fusion protein reversed this imbalance, suppressed aberrant PI3K–AKT–mTOR signalling and protected against placental injury, thereby demonstrating that checkpoint modulation can rescue both maternal vascular adaptation and foetal viability. This work establishes PD-L1 as a potential target for immunotherapeutic intervention in pre-eclampsia.

Regulatory T Cell Dynamics in Maternal-Fetal Immunity publication trend

The graph below shows the total number of articles in regulatory t cell dynamics in maternal-fetal immunity across all publications each year (not limited to Nature Index journals).

Technical terms

Regulatory T cell (Treg): A subset of CD4+ T lymphocytes expressing FOXP3 and CD25 that suppresses immune responses to maintain tolerance.

PD-1/PD-L1 pathway: An immune checkpoint interaction between PD-1 on T cells and PD-L1 on antigen-presenting or trophoblast cells that inhibits T cell activation.

Th17 cell: A pro-inflammatory CD4+ T cell subset producing interleukin-17, often counterbalanced by Tregs.

Decidua: The specialised endometrial lining of the uterus that interfaces with the placenta during pregnancy.

Trophoblast: Foetal-derived cells forming the outer layer of the placenta that interact with maternal immune cells.

References

1. Regulatory T cells are paramount effectors in progesterone regulation of embryo implantation and fetal growth. JCI Insight (2023).
2. Decidual macrophages derived NO downregulates PD-L1 in trophoblasts leading to decreased Treg cells in recurrent miscarriage. Frontiers in Immunology (2023).
3. The Role of Regulatory T Cells and Their Therapeutic Potential in Hypertensive Disease of Pregnancy: A Literature Review. International Journal of Molecular Sciences (2024).
4. Clonally Expanded Decidual Effector Regulatory T Cells Increase in Late Gestation of Normal Pregnancy, but Not in Preeclampsia, in Humans. Frontiers in Immunology (2018).
5. The PD-1/PD-L1 inhibitory pathway is altered in pre-eclampsia and regulates T cell responses in pre-eclamptic rats. Scientific Reports (2016).