Association of miR-34a-3p/5p, miR-141-3p/5p, and miR-24 in Decidual Natural Killer Cells with Unexplained Recurrent Spontaneous Abortion

Abstract

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/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.

Figure 1

Identification of decidual CD56+ CD3− NK cells from patients with URSA and controls. The purity of CD56+ CD3− NK cells in decidua was more than 70%. These cells were sorted using flow cytometric analysis. URSA – unexplained recurrent spontaneous abortion.

Figure 2

Quantification of miRNA expression levels in the URSA and control groups using real-time RT-PCR. Compared to the control group, 5 miRNAs (miR-34a, miR-155, miR-141, miR-125a, and miR-125b) were up-regulated, while miR-24 was down-regulated. ** P<0.01, *** P<0.001.

Figure 3

KEGG pathway analysis of predicted targets of 3 miRNAs. The analysis revealed 140 pathways (see the Supplementary Figure 1). The 29 most significant pathways are presented, including PI3K-Akt, focal adhesion, MAPK, Wnt, regulation of the actin cytoskeleton, T cell receptor, TGF-beta, and estrogen signaling pathways.