Abstract 11596: Amyloidogenic Medin Induces Endothelial Cell Prothrombotic Activation

Background: Vascular aging is characterized by acquisition of a pro-inflammatory and prothrombotic vascular phenotype independent of cardiovascular metabolic risk factors through still unknown mechanisms. Medin is an amyloidogenic peptide formed as a cleavage product of milk fat globule EGF factor 8 protein. It accumulates in the vasculature with aging and is one of the most common yet poorly understood human amyloid proteins. Cerebrovascular medin was shown to be strongly associated with vascular dementia and Alzheimer’s disease. It was shown to induce endothelial pro-inflammatory activation and endothelial dysfunction. We aim to test the hypothesis that medin induces prothrombotic activation in endothelial cells. Methods: Recombinant medin was expressed in Lemo 21 (DE3 cells) and purified. Human umbilical vein endothelial cells (HUVECs) were exposed to either vehicle or medin (5 μM, a dose found to be physiologically relevant in human tissue) for 20 hours. Cell lysates were measured for protein content of tissue factor (TF, receptor and cofactor for factor VII and initiates coagulation), plasminogen activator inhibitor-1 (PAI-1, inhibits plasminogen activators that promote fibrinolysis) and thrombomodulin (cell surface glycoprotein that inhibits procoagulant function of thrombin) using standard Western blot and compared. Results: See Figure. Physiologic dose of medin induced increased endothelial cell protein expression of TF, PAI-1 and reduced expression of thrombomodulin. Conclusions: Medin induces prothrombotic activation in human endothelial cells and may be a key novel mediator in the development of vascular aging phenotype.