BACKGROUND: The specific causes of recurrent spontaneous abortion (RSA) remain unknown in 37–79% of affected women. The aim of this study was to explore the expression levels of 6 miRNAs in natural killer (NK) cells from the decidua of patients with unexplained RSA (URSA) and to predict the target genes of 3 miRNAs.

MATERIAL AND METHODS: Two groups were examined: URSA (n=20) and controls (n=20). Flow cytometry analysis was used to identify NK cells isolated from the decidua. Transcriptional levels of miRNA were monitored using quantitative real-time reverse transcription-polymerase chain reaction. Prediction and analysis of mRNA targets of differentially expressed miRNAs were performed using bioinformatics methods.

RESULTS: Five miRNAs [miR-34a (+281%, P<0.001), miR-155 (+396%, P<0.001), miR-141 (+142%, P<0.01), miR-125a (+279%, P<0.001), and miR-125b (+185%, P<0.001)] were up-regulated, while miR-24 was down-regulated (–64%, P<0.01) in the URSA group, compared to the control group. This study identified potential miRNA targets: miR-34a-3p/5p, 585/1718 (targets of miR-34a-3p/targets of miR-34a-5p), miR-141-3p/5p, 2270/629 (targets of miR-141-3p/targets of miR-141-5p), and miR-24, 2320 target genes. A total of 140 pathways related to target genes were identified including PI3K-Akt, focal adhesion, MAPK, Wnt, regulation of the actin cytoskeleton, T cell receptor, TGF-β, and estrogen signaling pathways.

CONCLUSIONS: This study suggests that miR-34a-3p/5p, miR-141-3p/5p, and miR-24 in decidual NK cells could be associated with URSA. These findings might contribute to the panel of diagnostic and prognostic biomarkers with clinical utility, and facilitate the development of new strategies for targeted therapy against URSA.

Keywords: Abortion, Habitual - genetics, Decidua - pathology, Gene Expression Regulation, Killer Cells, Natural - metabolism, Pregnancy, Real-Time Polymerase Chain Reaction, Signal Transduction - genetics