MiR-181b regulates atherosclerotic inflammation and vascular endothelial function through Notch1 signaling pathway

To explore the influences of micro ribonucleic acid (miR)-181b on the inflammation and vascular endothelial function in atherosclerosis (AS), and its specific molecular regulatory mechanism.

44 apolipoprotein E (ApoE)-/- 7 weeks old male rats were randomly divided into normal diet group (NC group) and AS model group (high-fat diet feeding). Rat aorta was dissected and the serum sample was collected in both groups. The serum levels of inflammatory factors in both groups were detected via enzyme-linked immunosorbent assay (ELISA). The mRNA levels of miR-18b and Notch1 were detected via Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Moreover, aortic endothelial cells were extracted from AS rats. The mir-18b binding target gene was analyzed via bioinformatics and further verified by the Luciferase reporter gene assay. The protein expressions of miR-18b and Notch1 in endothelial cells transfected with miR-181b mimic or inhibitor were detected. Influence of miR-181b on vascular endothelial indexes was also detected.

Compared with those in the NC group, the serum levels of interleukin-6 (IL-6), IL-10, IL-13 and tumor necrosis factor-α (TNF-α) in the AS group significantly increased (p<0.05). The mRNA level of miR-18b in AS plaques was significantly lower than that in NC arterial tissues. Conversely, Notch1 level in AS plaques was markedly higher than that in the NC arterial tissues (p<0.05), with the mean difference of 2.12 and 2.82 folds (p<0.05). According to the Pearson correlation analysis, there was a significant negative correlation between mRNA levels of miR-181b and Notch1 in AS tissues (r=-0.65, p=0.014). The bioinformatics analysis showed that there were complementary binding sites between miR-181b and Notch1. The Luciferase reporter gene assay confirmed the presence of direct binding sites between miR-181b and Notch1. Western blotting revealed that the overexpression of miR-181b downregulated Notch1 and hs-CRP, but upregulated BNP (p<0.05). Opposite trends were obtained by miR-181b knockdown (p<0.05).

The decline in the miR-181b expression may be an important factor in AS plaque formation and vascular endothelial injury by regulating Notch1.