Exosomes released from decidual macrophages deliver miR-153-3p, which inhibits trophoblastic biological behavior in unexplained recurrent spontaneous abortion.

Background: Spontaneous abortion is a common disease in human pregnancy. Increasing evidence suggests that proper function of trophoblasts and immune balance of the maternal-fetal interface are crucial for successful pregnancy. Macrophages are involved in the maternal-fetal immune microenvironment. However, mechanisms associated with how macrophages impair trophoblasts' function in spontaneous abortion remain to be explored.

Methods: Firstly, the characteristics of the isolated macrophage-derived exosomes were verified by TEM and Western blot. Then, we established the co-culture of macrophage-derived exosomes with trophoblasts, and explored the role of the exosomes in trophoblasts. Moreover, expression of miR-153-3p in the macrophage-derived exosomes was detected. A miR-153-3p mimic was transfected into trophoblasts to investigate its function in the biological functions of trophoblast cells. MRNA and protein expressions were detected by qRT-PCR and Western blot. CCK8 assay was performed to measure cell proliferation and Transwell assay was utilized to examine migration of trophoblasts.

Results: Compared with those in normal pregnant women, decidual macrophage-derived exosomes from unexplained recurrent spontaneous abortion (URSA) patients suppressed the proliferation and migration of trophoblast cells through the IDO/STAT3 pathway. MiR-153-3p was highly expressed in exosomes released from decidual macrophages of URSA patients. Transfecting miR-153-3p mimics into trophoblast cells directly inhibited IDO genes, which suppressed STAT3 pathway activation, regulating the biological behavior of trophoblast cells.

Conclusions: This study outlines the role of decidual macrophage-derived exosomal miR-153-3p in successful pregnancy maintenance, paving a new approach for the development of novel treatments for URSA.