The fetus in utero bears paternal antigens and should be rejected as a foreign graft by the maternal immune system, an immunological enigma described by Peter Medawar more than 50 years ago. Maternal leukocytes that populate the uterine decidua certainly play an important role in tolerance. They interact with placental extravillous trophoblasts (EVT) that attach to and invade the decidua. EVT express an unusual Class I MHC protein of unknown function, the HLA-G dimer that is found only in pregnant women and apes. The goal of this proposal is to characterize both maternal leukocytes and fetal EVT and to study their interactions that must contribute to various aspects of pregnancy, including remodeling of the uterine spiral arteries to increase blood flow to the developing fetus, implantation of the blastocyst (16 cell stage embryo) into the uterus and maternal- fetal tolerance. Decidual natural killer cells (~70% of leukocytes in the decidua that were characterized during the first 5 years of this project) contribute to maternal-fetal tolerance by several means. This proposal seeks to characterize the remaining major sets of decidual leukocytes, the macrophages (~20% of the leukocytes) and T cells (5-20%), to describe synapses that occur between these cells, and to expand our knowledge of the interaction of HLA-G dimer bearing EVT with decidual leukocytes. Microarray analysis will be used as a principal tool in characterizing human decidual macrophages in order to establish whether they are M2 regulatory macrophages and what factors they may secrete. They may have an important role in maternal-fetal tolerance and in uterine remodeling. Studies of decidual T cells (5-20% of the leukocytes) that include regulatory T cells will also be initiated. The EVT that invade the decidua and intermingle with the decidual leukocytes have been recently isolated. They will be characterized further and used to study their interaction with decidual natural killer cells and macrophages. We have already established that these interactions lead to the secretion of several cytokines and hypothesize that other proteins involved in maternal- fetal tolerance and in uterine remodeling are also secreted. Finally, the mechanism by which LIF contributes to implantation will be examined by studying its effects on EVT that express the LIF receptor. LIF knockout female mice are infertile because the blastocyst formed after conception cannot implant into the uterus. This project is directly related to reproductive failure in women, i.e. recurrent spontaneous abortion (RSA), some forms of infertility due to failure of implantation of the blastocyst, preeclampsia and fetal growth restriction due to the failure of vascular remodeling that provides an adequate blood supply.

Public Health Relevance

This project is in the area of reproductive immunology, i.e. the immunological interaction between maternal and fetal tissues. Its goal is to understand implantation of the early embryo into the uterus, uterine remodeling and maternal-fetal tolerance, i.e. the lack of maternal rejection of the fetus that carries foreign paternal antigens even though the mother's immune system remains intact. Knowledge of these mechanisms will improve our understanding of women's reproductive difficulties including recurrent spontaneous abortion, some forms of infertility (particularly those women who are unable to implant an embryo resulting from in vitro fertilization), fetal growth restriction and preeclampsia and may provide leads to alleviation of these problems of women's reproductive health.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Pregnancy and Neonatology Study Section (PN)
Program Officer
Prabhudas, Mercy R
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Harvard University
Schools of Arts and Sciences
United States
Zip Code
van der Zwan, Anita; Bi, Kevin; Norwitz, Errol R et al. (2018) Mixed signature of activation and dysfunction allows human decidual CD8+ T cells to provide both tolerance and immunity. Proc Natl Acad Sci U S A 115:385-390
Allan, David S J; Cerdeira, Ana Sofia; Ranjan, Anuisa et al. (2017) Transcriptome analysis reveals similarities between human blood CD3- CD56bright cells and mouse CD127+ innate lymphoid cells. Sci Rep 7:3501
Crespo, Ângela C; van der Zwan, Anita; Ramalho-Santos, João et al. (2017) Cytotoxic potential of decidual NK cells and CD8+ T cells awakened by infections. J Reprod Immunol 119:85-90
Crespo, Ângela C; Strominger, Jack L; Tilburgs, Tamara (2016) Expression of KIR2DS1 by decidual natural killer cells increases their ability to control placental HCMV infection. Proc Natl Acad Sci U S A 113:15072-15077
Ferreira, Leonardo M R; Meissner, Torsten B; Mikkelsen, Tarjei S et al. (2016) A distant trophoblast-specific enhancer controls HLA-G expression at the maternal-fetal interface. Proc Natl Acad Sci U S A 113:5364-9
Guerin, Leigh; Wu, Vernon; Houser, Brandy et al. (2015) CD1 Antigen Presentation and Autoreactivity in the Pregnant Human Uterus. Am J Reprod Immunol 74:126-35
Tilburgs, Tamara; Evans, J Henry; Crespo, Ângela C et al. (2015) The HLA-G cycle provides for both NK tolerance and immunity at the maternal-fetal interface. Proc Natl Acad Sci U S A 112:13312-7
Tilburgs, Tamara; Crespo, Ângela C; van der Zwan, Anita et al. (2015) Human HLA-G+ extravillous trophoblasts: Immune-activating cells that interact with decidual leukocytes. Proc Natl Acad Sci U S A 112:7219-24
Chen, Ting; Darrasse-Jèze, Guillaume; Bergot, Anne-Sophie et al. (2013) Self-specific memory regulatory T cells protect embryos at implantation in mice. J Immunol 191:2273-81
Tilburgs, Tamara; Strominger, Jack L (2013) CD8+ effector T cells at the fetal-maternal interface, balancing fetal tolerance and antiviral immunity. Am J Reprod Immunol 69:395-407

Showing the most recent 10 out of 13 publications