Trophoblast-derived chemokine CXCL12 promotes CXCR4 expression and invasion of human first-trimester decidual stromal cells

BACKGROUND: The aim of this study was to investigate the role of the chemokine (C-X-C motif) ligand 12/chemokine (C-X-C motif) receptor 4 (CXCL12/CXCR4) axis on the crosstalk between human first-trimester trophoblast cells (TCs) and decidual stromal cells (DSCs), to contribute to a better understanding of the molecular mechanisms on the interaction between the mother and embryo during pregnancy. METHODS: CXCR4 on human first-trimester DSC membranes was detected by flow cytometry. The effects of exogenous CXCL12 or TC-conditioned medium (TCM) on proliferation and invasion of DSCs were examined by measuring proliferating cell nuclear antigen (PCNA) and an invasion assay, respectively. Finally, a co-culture model was established to investigate the effect of CXCL12 secreted from TCs on motility of DSCs. RESULTS: The mean (+/- SEM) percentage of DSCs positive for CXCR4 was 32.32 +/- 7.18%. Human recombinant CXCL12 induced an increase in CXCR4 levels on DSCs via binding to CXCR4 (P < 0.01) but had no effect on the PCNA expression of DSCs. Moreover, both exogenous CXCL12 and TCM reinforced the invasive ability of DSCs via CXCR4 ligation. A co-culture model further confirmed that the enhanced invasiveness of DSCs in co-culture with TCs was inhibited by anti-CXCR4 or anti-CXCL12 neutralizing antibody (both P, 0.01). CONCLUSIONS: Human first-trimester DSCs express membrane CXCR4 and TC-derived CXCL12 promotes CXCR4 expression and invasion of DSCs via ligation with CXCR4. Our data highlight the role of CXCL12/CXCR4 axis on the co-operation between TCs and DSCs during human first-trimester pregnancy.