Maternal uterine NK cell–activating receptor KIR2DS1 enhances placentation
Shiqiu Xiong, … , Francesco Colucci, Ashley Moffett
Shiqiu Xiong, … , Francesco Colucci, Ashley Moffett
Published September 16, 2013
Citation Information: J Clin Invest. 2013;123(10):4264-4272. https://doi.org/10.1172/JCI68991.
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Research Article Reproductive biology

Maternal uterine NK cell–activating receptor KIR2DS1 enhances placentation

Abstract

Reduced trophoblast invasion and vascular conversion in decidua are thought to be the primary defect of common pregnancy disorders including preeclampsia and fetal growth restriction. Genetic studies suggest these conditions are linked to combinations of polymorphic killer cell Ig-like receptor (KIR) genes expressed by maternal decidual NK cells (dNK) and HLA-C genes expressed by fetal trophoblast. Inhibitory KIR2DL1 and activating KIR2DS1 both bind HLA-C2, but confer increased risk or protection from pregnancy disorders, respectively. The mechanisms underlying these genetic associations with opposing outcomes are unknown. We show that KIR2DS1 is highly expressed in dNK, stimulating strong activation of KIR2DS1+ dNK. We used microarrays to identify additional responses triggered by binding of KIR2DS1 or KIR2DL1 to HLA-C2 and found different responses in dNK coexpressing KIR2DS1 with KIR2DL1 compared with dNK only expressing KIR2DL1. Activation of KIR2DS1+ dNK by HLA-C2 stimulated production of soluble products including GM-CSF, detected by intracellular FACS and ELISA. We demonstrated that GM-CSF enhanced migration of primary trophoblast and JEG-3 trophoblast cells in vitro. These findings provide a molecular mechanism explaining how recognition of HLA class I molecules on fetal trophoblast by an activating KIR on maternal dNK may be beneficial for placentation.

Authors

Shiqiu Xiong, Andrew M. Sharkey, Philippa R. Kennedy, Lucy Gardner, Lydia E. Farrell, Olympe Chazara, Julien Bauer, Susan E. Hiby, Francesco Colucci, Ashley Moffett

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Figure 6

Effect of GM-CSF on trophoblast migration.

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Effect of GM-CSF on trophoblast migration. (A) Immunohistochemistry of h...
(A) Immunohistochemistry of human implantation site. HLA-G+ EVT (red) and CD56+ dNK (brown). (B) The close association of dNK with EVT is obvious at higher power. (C–E) Immunofluorescence staining of serial section to A. HLA-G+ EVT (green, arrow in C) coexpress GM-CSFRα (red, D) as seen in the overlay in E. Scale bars: 250 μm (A); 25 μm (B–E). (F) Expression of GM-CSFRα on primary EVTs (stained for HLA-G in gate R1 after gating out CD14+ placental macrophages). Histogram shows isotype control (red line) and GM-CSFRα staining (blue line) of the HLA-G+ EVT in R1. (G) JEG-3 cells show increased migration in a Transwell assay in response to supernatant conditioned by dNK from KIR2DS1+ donors after crosslinking with EB6 (super). Addition of neutralizing antibody against GM-CSF to the supernatant (super + GM-CSF mAb) significantly reduced JEG-3 migration compared with supernatant plus isotype control mAb (super + IgG con). Results are presented as the calcein dye fluorescence measured in the lower chamber 48 hours after seeding. Horizontal bars show mean for each group (n = 5). *P < 0.05, Student’s paired t test. (H) Primary trophoblast cells show increased migration in a Transwell assay in response to 10 ng/ml GM-CSF added to the lower chamber. Control wells had no added GM-CSF. Results are presented as the number of EVT counted in the sampled fields (n = 4). *P < 0.01, Student’s t test.