Immunological Mechanisms at the Maternal-Fetal Interface

At the maternal–fetal interface, a finely orchestrated dialogue between maternal immune cells, placental trophoblasts and stromal elements ensures tolerance of the semi-allogeneic foetus while retaining defence against pathogens. Early pregnancy involves a pro-inflammatory milieu to facilitate implantation and placentation, followed by a predominantly anti-inflammatory phase that supports foetal growth, and culminating in renewed inflammation at parturition. Key players include decidual natural killer cells that guide spiral artery remodelling; macrophages that clear debris and secrete cytokines; regulatory T and B lymphocytes that suppress effector responses; and myeloid-derived suppressor cells that reinforce tolerance via indoleamine 2,3-dioxygenase and other mediators. Crosstalk is mediated by checkpoint receptors such as Tim-3, endocrine modulators including progesterone and human chorionic gonadotropin, and a network of cytokines (for example interleukin-10 and transforming growth factor-β). Disruption of these mechanisms underpins disorders such as preeclampsia, recurrent loss and preterm birth, and informs novel diagnostics and therapeutic strategies.

Research from Nature Portfolio

Recent studies have shown that Toxoplasma gondii infection impairs maternal–foetal tolerance by downregulating IDO protein in decidual MDSCs via STAT3/p52-RelB upregulation and SOCS3-mediated degradation, leading to reduced TGF-β and IL-10 secretion by decidual NK cells and exacerbated pregnancy loss. Foundational work has also revealed that Tim-3 signalling in decidual stromal cells constitutes a self-control mechanism for TLR-induced inflammation, protecting these cells from apoptosis through ERK1/2 activation and suppressing NF-κB to promote a Th2 cytokine bias that preserves placental integrity.

Immunological Mechanisms at the Maternal-Fetal Interface publication trend

The graph below shows the total number of articles in immunological mechanisms at the maternal-fetal interface across all publications each year (not limited to Nature Index journals).

Technical terms

Decidual natural killer (dNK) cells: Uterine NK cells specialised for vascular remodelling, immunoregulation and support of placental development.

Myeloid-derived suppressor cells (MDSCs): Innate immune cells that inhibit T cell activation and promote tolerance via factors such as indoleamine 2,3-dioxygenase.

Indoleamine 2,3-dioxygenase (IDO): Enzyme that catabolises tryptophan into kynurenine, depleting local tryptophan and generating metabolites that suppress immune responses.

T-cell immunoglobulin mucin-3 (Tim-3): Immune checkpoint receptor on various leukocytes that modulates cytokine production and promotes tolerance.

Decidual stromal cells (DSCs): Differentiated endometrial cells in the decidua that interact with immune populations to maintain a supportive environment for the foetus.

Regulatory T (Treg) cells: CD4+ T lymphocytes that exert suppressive functions to prevent maternal immune rejection of the foetus.

Trophoblasts: Foetal-derived placental cells that invade maternal tissues to enable nutrient exchange and secrete immunomodulatory factors.

References

1. Decidual natural killer cells dysfunction is caused by IDO downregulation in dMDSCs with Toxoplasma gondii infection. Communications Biology (2024).
2. Tim-3 protects decidual stromal cells from toll-like receptor-mediated apoptosis and inflammatory reactions and promotes Th2 bias at the maternal-fetal interface. Scientific Reports (2015).
3. Tim-3 Coordinates Macrophage-Trophoblast Crosstalk via Angiogenic Growth Factors to Promote Pregnancy Maintenance. International Journal of Molecular Sciences (2023).
4. Characterization of B cells in healthy pregnant women from late pregnancy to post-partum: a prospective observational study. BMC Pregnancy and Childbirth (2016).
5. The Cellular Transcriptome in the Maternal Circulation During Normal Pregnancy: A Longitudinal Study. Frontiers in Immunology (2019).
6. Maternal Immunological Adaptation During Normal Pregnancy. Frontiers in Immunology (2020).
7. Endocrine Factors Modulating Immune Responses in Pregnancy. Frontiers in Immunology (2014).