Expression and significance of miR-155 during embryo implantation

Background: miRNAs are considered to be one of the important molecules involved in the regulation of multiple physiological functions of endometrium such as proliferation and decidualization, angiogenesis, immune regulation, adhesion and invasion. miR-155 is closely related to the occurrence of some diseases such as inflammation, tumor metastasis and immunity. In view of the extreme similarity in immune escape, angiogenesis, cell proliferation, differentiation and invasion between embryo implantation and tumorigenesis, we studied the role of miR-155 in embryo implantation. Methods Human endometrial tissues and decidual tissues were collected, and the mouse models of early pregnancy were constructed. The expression levels of miR-155 were analyzed by quantitative PCR. Results The expression levels of miR-155 in decidual tissues were significantly lower than that of endometrial tissues in the middle secretory stage ( P < 0.05). The results of mouse models showed that the endometrial decidualization progressed gradually with the increase of gestational days, and that the expression levels of miR-155 in endometrial tissues decreased gradually with the increase of gestational days ( P < 0.05). On day 5 of pregnancy, the expression levels of miR-155 in endometrial tissues of embryo implantation sites were significantly lower than that in inter-implantation sites ( P < 0.05). The amount of embryo implantation in the uterus injected by mmu-miR-155 agomir was significantly lower than that by normal control agomir ( P < 0.05). Conclusions During the embryo implantation of early pregnancy, the expression level of miR-155 in endometrial tissues decreased significantly with the increase of pregnancy time, which may be related to endometrial decidualization.