Natural killer cells (NKs) are abundant in the human decidua, regulating trophoblast invasion and angiogenesis. Several diseases of poor placental development are associated with first pregnancies, so we thus looked to characterize differences in decidual NKs (dNKs) in first versus repeated pregnancies. We discovered a population found in repeated pregnancies, which has a unique transcriptome and epigenetic signature, and is characterized by high expression of the receptors NKG2C and LILRB1. We named these cells Pregnancy Trained decidual NK cells (PTdNKs). PTdNKs have open chromatin around the enhancers of IFNG and VEGFA. Activation of PTdNKs led to increased production and secretion of IFN-γ and VEGFα with the latter supporting vascular sprouting and tumor growth. The precursors of PTdNKs seem to be found in the endometrium. Because repeated pregnancies are associated with improved placentation, we propose that PTdNKs, which are present primarily in repeated pregnancies, might be involved in proper placentation. Natural killer cells are present in the human decidua, regulating trophoblast invasion and angiogenesis. Here, Gamliel et al. report on a special subset of human decidual natural killer cells, which “remember” pregnancy and better support subsequent pregnancies. This might explain why first pregnancies are at increased risk of developing diseases of poor placentation.
Bibliographical noteFunding Information:
This work was supported by the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement number 320473-BacNK. Further support came from the Israel Science Foundation, the GIF foundation, the Lewis family foundation, the ICRF professorship grant, the Helmholtz Israel grant and the Rosetrees Trust (all to O.M.). J.H.H. is supported by European Research Council, Flight Attendant Medical Research Council (FAMRI), Israel Science Foundation (ISF-ICORE, ISF-NFSC, ISF-Regular & ISF-Morasha programs), ICRF, and HFSP & New York Stem Cell Foundation (NYSCF). J.H.H. is a New York Stem Cell Foundation (NYSCF)–Robertson Investigator. We wish to thank the Bioinformatics Unit of the I-CORE Computation Center at the Hebrew University and Hadassah for the transcriptome analysis and Dr. Shari Orlanski for analyzing part of the epigenetic data. O.M. is a Crown Professor of Molecular Immunology. M. Gamliel is supported by the Hoffman Leadership and Responsibility fund, at the Hebrew University.
© 2018 Elsevier Inc.
- great obstetrical disorders
- natural killer cells
- trained immunity