Roles of exosome-associated glycosphingolipids in immune tolerance of embryo implantation and pregnancy

Abstract

Establishment of pregnancy requires synchronized growth between the endometrium and the blastocyst. Functional interaction between these occurs both during the pre-implantation phase of embryo implantation and during placentation. Pregnancy is a unique event in which a fetus, despite being genetically and immunologically different from the mother, develops in the uterus. Successful pregnancy implies avoidance of rejection by the maternal immune system. Exosomes released from the endometrium and the embryo are present in uterine fluid. These can transfer miRNA,mRNAs, proteins and lipids between cells, thus providing endometrial-embryo communication in the peri-implantation period. Exosomes have been considered of critical importance for embryo implantation and programming of human pregnancy. In the present study, we examined that the action of glycosphingolipids (GSLs) in exosomes, and their role as preventing the embryo from being attacked by the maternal immune system. In this in vitro study, we examined whether GSLs could be purified from exosomes derived from abortus villi. To demonstrate the immunomodulatory capacity of exosomes. To test macrophage M1/M2 polarization, indicating the role of exosomes in embryo implantation and pregnancy. Human villus trophoblast cells were isolated from the abortus tissue from healthy women undergoing pregnancy termination of a pregnancy at 6- to 12-wk gestation, after informed consent. GSLs transfected from exosomes to monocytes. Macrophage M1/M2 polarization was tested by flow cytometry with CD68/CD80/CD163 markers. Transmission electron microscopy (TEM) images of isolated exosomes were performed. GSLs were successfully transfected from exosomes to monocytes. Pretreatment with exosomes significantly induced macrophage M2 polarization. Moreover, isolated exosomes from villus trophoblast cells were confirmed by transmission electron microscopy images. Pretreatment with exosomes derived from villus trophoblast cells of a normal pregnancy significantly induced macrophage M2 polarization compared with anembryonic pregnancy through M1 macrophage marker expression by qRT-PCR. Our results demonstrate that GSLs were significant expressed in exosomes derived from villus trophoblast cells, indicating the GSLs have potential modulatory role on embryo implantation and decidual programming of human pregnancy. This study demonstrates that exosomes derived from villus trophoblast cells of a normal pregnancy significantly induced macrophage M2 polarization. Our findings represent a new concept regarding the immunomodulatory capacity of exosomes from embryos and villi, suggesting that exosomes have potential modulatory role on embryo implantation and decidual programming of human pregnancy.