CXCL12/CXCR4/CXCR7 axis in placenta tissues of patients with placenta previa

Abstract

CXCR4 and CXCR7 have been revealed to be receptors of CXCL12. This research was designed to probe the expression of chemokine CXCL12 and its receptors CXCR4 and CXCR7 in placental tissues of patients with placenta previa and the effect of CXCL12/CXCR4/CXCR7 axis on the biological functions of human trophoblast cells. CXCL12, CXCR4, and CXCR7 expression in placental tissue from patients with placenta previa and healthy puerperae was detected. CXCL12, CXCR4, and CXCR7 expression in human trophoblast cell lines (HTR8/SVneo cells) was assessed after suppression or overexpression of CXCL12, CXCR4, and CXCR7. The cell proliferative, invasive, and migratory capacities were also evaluated in HTR8/SVneo cells after suppression or overexpression of CXCL12, CXCR4, and CXCR7. CXCL12, CXCR4, and CXCR7 expression was elevated in placental tissues from patients with placenta previa. Downregulation of CXCL12, CXCR4, and CXCR7 could lead to decreased mRNA levels of CXCL12, CXCR4, and CXCR7 in HTR-8/SVneo cells, which was accompanied by diminished cell proliferative, migratory, and invasive capabilities. Overexpression of CXCL12, CXCR4, and CXCR7 genes presented an opposite tendency. CXCL12, CXCR4, and CXCR7 are highly expressed in placental tissues of patients with placenta previa and induce the biological activities of HTR8/SVneo cells.

Keywords: CXCL12; CXCR4; CXCR7; human trophoblast cells; placenta previa; placental tissue.

Figure 1

CXCL12, CXCR4, and CXCR7 are expressed at a high level in placental tissues of the puerperae with placenta previa. (a) and (b) CXCL12, CXCR4, and CXCR7 levels in placental tissues were measured by IHC. (c) CXCL12, CXCR4, and CXCR7 mRNA levels in placental tissues were also evaluated by RT-qPCR assay. *P < 0.05.

Figure 2

CXCL12, CXCR4, and CXCR7 expression in human trophoblast HTR-8/SVneo cells silencing or overexpressing CXCL12, CXCR4, and CXCR7. (a–c) mRNA expression levels of CXCL12, CXCR4, and CXCR7 were measured in cells overexpressing CXCL12, CXCR4, and CXCR7 by qRT-PCR. (d–f) mRNA expression levels of CXCL12, CXCR4, and CXCR7 were evaluated in cells silencing CXCL12, CXCR4, and CXCR7 by RT-qPCR. *P < 0.05.

Figure 3

Effects of suppression or overexpression of CXCL12, CXCR4, and CXCR7 on HTR-8/SVneo cell viability. (a) CCK-8 assay for evaluating the roles of overexpressing CXCL12, CXCR4, and CXCR7 in HTR-8/SVneo cell viability (b) CCK-8 assay for evaluating the roles of silencing CXCL12, CXCR4, and CXCR7 in HTR-8/SVneo cell viability. *P < 0.05.

Figure 4

Effect of silencing or restoration of CXCL12, CXCR4, and CXCR7 on the migratory and invasive capacities of human trophoblast HTR-8/SVneo cells. (a) and (b) Cell scratch test was implemented for assessing the HTR-8/SVneo cell migration capability after overexpression of CXCL12, CXCR4, and CXCR7. (c) and (d) Cell scratch test was implemented for assessing the HTR-8/SVneo cell migration capability after suppression of CXCL12, CXCR4, and CXCR7. (e) and (f) The number of cells crossing the human-like basement membrane in the HTR-8/SVneo cells after overexpression of CXCL12, CXCR4, and CXCR7 was observed microscopically using the Transwell invasion assay. (g) and (h) The number of cells crossing the human-like basement membrane in the HTR-8/SVneo cells after suppression of CXCL12, CXCR4, and CXCR7 was observed microscopically using the Transwell invasion assay. *P < 0.05.