miR-374b-5p is increased in deep vein thrombosis and negatively targets IL-10

Background: Deep venous thrombosis (DVT) is one of the most common venous thromboembolic (VTE) disorders and the third leading cardiovascular complication. Accumulating evidence has shown that decreased interleukin-10 (IL-10) was involved in DVT. However, the underlying molecular mechanisms are still largely unknown. Here, we proposed that the epigenetic modification of IL-10 at the post-transcriptional level may be a crucial trigger for IL-10 down-regulation in DVT.

Methods: miRNA expression in DVT was profiled by miRNA microarray analysis. The upstream miRNA regulators of IL-10 were predicted by in silico target prediction tools. The expression of IL-10 mRNA and miR-374b-5p were examined by quantitative real-time PCR (qRT-PCR) and the protein expression of IL-10 was detected by enzyme-linked immunoassay. Dual luciferase reporter assay was used to identify the interaction between miR-374b-5p and IL10. A murine model of DVT was developed and the localization of miR-374b-5p was visualized in vitro by fluorescence in situ hybridization. The biological effects of miR-374b-5p on IL-10 was examined both in vitro and in vivo.

Results: Microarray and qRT-PCR results showed that the IL-10 expression was decreased while miR-374b-5p level was increased substantially in peripheral blood mononuclear cells of DVT patients, and there was significant negative correlation between miR-374b-5p and IL-10. Experiments in vitro showed that overexpressed miR-374b-5p reduced IL-10 expression, while miR-374b-5p knockdown increased IL-10 expression. Moreover, in vivo studies revealed that DVT mice with anti-IL-10 antibody or agomiR-374b-5p delivery resulted in decreased IL-10 expression and aggravated DVT formation, whereas antagomiR-374b-5p acted inversely. Dual luciferase reporter assay identified direct binding between miR-374b-5p and IL10.

Conclusions: These findings suggest that increased miR-374b-5p promotes DVT formation by downregulating IL-10 expression. miR-374b-5p may be explored as a promising diagnostic marker and therapeutic target for DVT.