(193) miR-146a; a potential link connecting shear stress-induced activation of Osteopontin & TLR-4 pathways.

Objective : Our preliminary studies showed increased levels of Osteopontin (OPN), a shear-sensitive matricellular protein that promotes vascular inflammation, along with its receptor alphaV-Beta3 and downstream TRAF6, in Human Aortic Endothelial Cells (HAECs) subjected to oscillatory shear-stress (OSS) versus unidirectional shear stress (USS) control conditions. The goal of our work is to evaluate whether the over-expression of miR-146a can modulate OSS-induced expression levels of OPN and associated TLR-4 downstream signaling pathways.

Methods: Human Aortic Endothelial Cells (HAECs) were subjected to simultaneous OSS and USS control conditions using the standard orbital shaking model in vitro. miR-146a and scramble control were over- expressed using standard transfection protocols. Levels of OPN, its receptor alphaV-Beta3 and TLR-4 & downstream signaling pathway were compared between groups using western blot analyses.

Results: Our preliminary results showed that in parallel to increased trends of OPN & its receptor alphaV-Beta3 in HAECs subjected to OSS conditions compared to USS conditions, there was an associated increase in TLR-4 receptor and downstream TRAF6 levels. Whereas levels of downstream TICAM, HuR, IRF3, and MYD88 signaling pathways were not significantly different. HAECs cultured under static control conditions showed no difference in expression between HAECs isolated from the edge versus the center of the culture dish. Over-expression of miR-146a showed a trend towards blunted expression of OSS-induced OPN, alphaV-Beta3, TRAF6 & TLR-4 receptor levels compared to scramble control.

Conclusions: Our findings suggest miR-146a; as a potential link connecting shear stress- induced activation of the pro-inflammatory and pro-proliferative OPN & TLR-4 pathways. Further studies are warranted for confirming the anti-atherogenic effects of miR-146a and its direct interaction with the OPN & TLR-4 pathways as a foundation for developing innovative miR-based therapeutic modalities for atherosclerosis.