Lipopolysaccharide alters cell communication at the maternal-fetal interface revealed by single-cell RNA-sequencing

Embryo implantation is a decisive process in pregnancy that highly relies on effective cell communication at the maternal-fetal interface. Embryo implantation failure is frequently caused by gram-negative bacterial infection, therefore, this study aimed to investigate the effect of Lipopolysaccharides (LPS)-induced inflammation on cellular composition, cell-cell interaction and key signaling pathways at the maternal-fetal interface using Single-cell RNA-Sequence (scRNA-Seq). LPS exposure significantly up-regulated the expression of pro-inflammatory cytokines, CCL-2, TNF-α, and IL-1β in maternal-fetal interface tissues as well as triggered the recruitment of neutrophils, monocytes and eosinophils into peripheral blood. scRNA-Seq revealed endometrial epithelial cells (EpCs), stromal cells (ESCs), Fibroblasts (FiCs) and 15 other cell types. LPS administration significantly shifted the cellular proportions, increased populations of immune cells and fibroblasts while decreased ESCs and EpCs. Cellular differentiation indicated that all ESCs originated from ESC8 while ESC2 and 7 were the most differentiated ESC subtypes. Likewise, cellular communication demonstrated notable differences, reversed interactions were observed exclusively on the LPS exposure between luminal epithelial (LE) and glandular epithelial (GE) cells. ESC8 was inactive in the control group but exhibited robust interactions in the LPS group. Furthermore, the communication analysis predicted significant disruptions in the signaling pathways: Embryo-maternal communications (DHEA, BMP, LIFR, EDN, and NEGR pathways). Endometrial stromal-epithelial crosswalks (5αP, CAECAM, DHEAS and HH pathways) and Endometrial stromal-immune cell interactions (EGF and NCAM pathways). Our findings suggest that signaling pathways are essential for maternal-fetal communication. The disruption of the pathways in response to LPS may provide new molecular targets for diagnosing and treating implantation failure and recurrent pregnancy loss.