Firstly, dNK promote vascular
growth in the decidua through the production of vascular
endothelial growth factor (VEGF) and placental growth factor
(PlGF) (9, 13, 17–19) as well as of angiopoietin 1, angiopoietin
2, and TGF-b1 (15, 20). The release of these proangiogenic factors by dNK cells depends on the engagement of both NKp30 and
NKp44 activating receptors by their specific ligands present on
stromal decidual cells and extravillous trophoblast (17). Engagement of another NK cell receptor, KIR2DL4, by soluble HLA-G
specific ligand was shown to induce the production of proangiogenic cytokines (21). Since KIR2DL4 is expressed by dNK either
at the cell surface (22) or intracellularly (21), and soluble HLAG is secreted by trophoblast (23), this receptor-ligand couple is
likely to contribute to the remodeling of the maternal vasculature
in early pregnancy. The same authors have demonstrated that the
KIR2DL4-induced senescence secretome of PB-NK can promote
vascular remodeling and angiogenesis (24). Analysis of the dNK
cell transcriptome revealed a strong similar senescence signature
(24). Secondly, dNK release interleukin-8 (IL-8) and interferoninducible protein-10 (IP-10) chemokines that favor the migration
of the extravillous cytotrophoblast into the decidua basalis by
interacting with the CXCR3 and CXCR1 receptors expressed by the
trophoblast cells (17). Migration of extravillous trophoblast cells
results in the invasion of spiral arteries thus contributing to the
uterine vascular remodeling crucial for the placental development
and outcome of pregnancy (25). Such production of chemoattractants by dNK is due to the engagement of NKp30 and NKp44 by
their specific ligands expressed by trophoblast and stromal decidual cells (17). Similar interactions between dNK and trophoblas