Abstract 17221: Stable Flow-Induced Expression of KLK10 Inhibits Endothelial Inflammation and Atherosclerosis

Introduction: Atherosclerosis preferentially occurs in arterial regions exposed to disturbed blood flow ( d-flow ) while the straight regions exposed to stable flow ( s-flow ) are protected. The proatherogenic and atheroprotective effects of flow are mediated in large part by the global changes in endothelial cell gene expression, which regulate endothelial dysfunction and inflammation. Previously, we identified Kallikrein-Related Peptidase 10 (KLK10) as one of the most flow-sensitive genes in arterial endothelial cells using the partial carotid ligation model of d-flow -induced atherosclerosis. KLK10 is a secreted serine protease, but its role in endothelial function and atherosclerosis is unknown. Methods/Results: Here, we validated that KLK10 was upregulated under s-flow conditions and downregulated under d-flow conditions using the in vivo mouse models and in vitro studies using endothelial cells (ECs). Through in vitro functional studies using ECs, we found that KLK10 produced by s-flow protected against endothelial inflammation and permeability dysfunction. Furthermore, treatment with rKLK10 or overexpression of KLK10 plasmids in vivo decreased endothelial inflammation the mouse model. Further, rKLK10 injection or ultrasound-mediated transfection of KLK10 plasmids in the hind leg muscles led to inhibition of atherosclerosis in ApoE-/- mice with the partial carotid ligation surgery. Studies using the pharmacological inhibitors and siRNAs showed that the anti-inflammatory effects of KLK10 was mediated by the Protease Activated Receptors 1 and 2, but without directly cleaving them. Further studies show that KLK10’s anti-inflammatory effect was mediated by the NFκB and VCAM1 and ICAM1 expression pathway. In addition, immunostaining showed that KLK10 expression is significantly reduced in human coronary arterial sections with atherosclerotic plaques compared to the non-diseased controls. Conclusions: We found that KLK10 is a potent flow-sensitive secreted protein, which serve as a novel anti-inflammatory and anti-atherogenic factor. KLK10 may be a potential anti-atherogenic therapeutic.