Differential expression of microRNAs in human endometrium after implantation of an intrauterine contraceptive device containing copper.

Intrauterine devices containing copper placement will release a large amount of Cu2+ into the uterine fluid, leading to local endometrial damage and inflammation, which is considered to be one of the causes of abnormal uterine bleeding. Studies have shown that the metabolism and function of metal ions are related to the regulation of microRNA. The aims of this study were to investigate changes in endometrial microRNA levels after implantation of an intrauterine device containing copper and to preliminarily explore the signalling pathways involved in abnormal uterine bleeding. The subjects were fertile women, aged 25-35, without major obstetrics and gynaecology diseases. Human endometrial tissues were collected before implantation or removal of the intrauterine device containing copper. High-throughput microRNA sequencing was performed on human endometrial tissues, and real-time quantitative PCR, western blotting and immunohistochemistry were used to detect the expression of relevant genes. MicroRNA sequencing results showed that 72 miRNAs were differentially expressed in the endometrial tissue after the insertion of the intrauterine device containing copper. Implantation of an intrauterine device containing copper implantation can up-regulate the expression of miR-144-3p in endometrial tissue, and therefore, decreases the mRNA and protein expression levels of genes related to endometrial injury and tissue repair, including the MT/NF-κB/MMP damage pathway and the THBS-1/TGF-β/SMAD3 repair pathway. In this study, the molecular mechanisms of abnormal uterine bleeding due to an intrauterine device containing copper were preliminarily investigated. The information will be beneficial for the clinical treatment of abnormal uterine bleeding caused by intrauterine device.