Abstract 592: Rapamycin Increases the Thrombogenic Potential of Neutrophil Extracellular Traps (NETs): Potential Mechanism of Prothrombotic Drug-Eluting Stents
Background: Neutrophil leukocytes are considered among the first cellular responders to bacterial host tissue infection. At sites of inflammation, neutrophils can undergo activation, releasing their nuclear content by freeing hydrolases from lysosomes to form microbicidal protein exposing neutrophil extracellular traps (NETs). NETs provide a structural framework for pathogen clearance; however, recent studies have demonstrated that NETs may additionally contribute to thrombotic complication including deep vein thrombosis. We have previously demonstrated a critical role for the mammalian target of rapamycin (mTOR) pathway regulating autophagy to promote NETs formation. Second-generation drug-eluting stents (DES) containing rapamycin have successfully reduced the rate of restenosis; however, they are associated with thrombotic complications. The mechanism by which mTOR inhibition by rapamycin promotes in-stent thrombosis remains ill-defined.
Aims: To determine the role of mTOR regulation during NETs formation to regulate the thrombogenic potential of NETs.
Results: Purified human neutrophils were stimulated with N-Formyl-Met-Leu-Phe (fMLP) in the presence of rapamycin to induce NETs. We found that NETs bound coagulation factors fibrinogen, prothrombin and FXI in platelet-poor plasma. In an ex vivo model of occlusive thrombus formation, NETs formation accelerated occlusive thrombus formation in recalcified whole blood. Inhibition of activated FXII (FXIIa) with corn trypsin inhibitor or inhibition of FXI activation by FXIIa or factor IX activation by FXIa abrogated the procoagulant activity of NETs.
Conclusions: Our data demonstrate a role for the mTOR pathway in the presence of fMLP to regulate the procoagulant activity of NETs, suggesting a possible mechanism by which rapamycin in DESs promotes thrombosis.
Author Disclosures: D.K. Robinson: None. L.D. Healy: None. T.T. Chu: None. H. Oldenkamp: None. C. Garcia Puy: None. A. Gruber: None. O.J.T. McCarty: None.
This research has received full or partial funding support from the American Heart Association.
- © 2015 by American Heart Association, Inc.