Blood reflux-sensitive microRNAs in venous endothelium are correlated with the development of human chronic venous...

Flow-sensitive microRNAs (miRs) (e.g. miR-10a, miR-126-5p, miR-663, and miR-92a) are vital regulators of hemodynamics (i.e. pro-atherogenic or anti-atherogenic flow) that modulate aortic endothelial cell (EC) function and atherosclerosis development. We aimed to determine the roles of flow-sensitive miRs in venous ECs in response to blood reflux and correlate these miRs with chronic venous disease (CVD) development.

In-vivo human studies (i.e. human varicose veins with different levels of blood reflux vs. human normal veins with normal venous flow) and in-vitro flow experiments were used to examine the role of blood reflux in modulating the signaling of miR-10a, miR-126-5p, miR-663, and miR-92a.

We found that the expression of anti-inflammatory miR-10a and vascular repair-associated miR-126-5p was inhibited in the endothelium of varicose veins with blood reflux, and the expression of their direct targets, inflammatory GATA6 and anti-proliferative DLK1, was upregulated. In contrast, inflammatory miR-663 and miR-92a were overexpressed in the endothelium of varicose veins with blood reflux, whereas the expression of their targets, anti-inflammatory KLF4 and KLF2, was downregulated. We further demonstrated that blood reflux-induced oscillatory flow plays a major role in the overexpression of GATA6 and DLK1 and the inhibition of KLF4 and KLF2 expression in venous ECs. In-vitro transfection of a precursor miR (i.e. miR-10a or miR-126-5p) or antagomiR (i.e. miR-663 or miR-92a) to venous ECs abolished such blood reflux-induced pathogenic signaling.

Our findings indicate that the expression of anti-inflammatory miR-10a and vascular repair-associated miR-126-5p is inhibited, but inflammatory miR-663 and miR-92a are overexpressed in the endothelium of human varicose veins with blood reflux to modulate venous EC pathogenic signaling related to inflammation or turnover imbalance, which is highly related to human CVD progression. Moreover, blood reflux-modulated miRs have the potential to be developed as diagnostic biomarkers or therapeutic targets for human CVD.