Abstract 20277: Inhibition of vWF Secretion Prevents Microvascular Thrombosis in CLP Rodent Models of Sepsis
Severe sepsis is associated with microcirculatory collapse and disseminated intravascular coagulation (DIC) as a result of interdependent mechanisms of systemic intravascular inflammation, vascular leakage, microvascular thrombosis, and thrombocytopenia. Currently, no drug is available to concomitantly treat these events in sepsis. A poorly understood mechanism and yet critical determinant of sepsis-induced vascular inflammation and microvascular thrombosis is von Willebrand Factor (vWF) secretion by activated endothelial cells (ECs). We recently discovered that Gα12 heterotrimeric G protein plays a critical role in basal and evoked vWF secretion by endothelial cells by promoting Weibel Palade body fusion and exocytosis (Rusu et al Blood 2014). Based on the observed direct interaction of Gα12 with αSNAP, a critical member of the exocyst complex required for membrane fusion events, we generated an inhibitory peptide which we hypothesized would selectively and potently inhibit vWF secretion and thrombosis without adversely inducing hemorrhage and vascular leakage in rodent models of sepsis. We assessed the effect of Gα12 knockout and Myr-αSNAP Binding Domain (SBD) Gα12 N-terminal peptide on VWF secretion and mortality associated with cecal ligation and puncture (CLP) induced sepsis. CLP-induced fulminant sepsis in rats and mice was associated with a 3-fold increase in plasma vWF within 6-9 hrs and 2-fold increase at 24 hrs. Importantly, we observed reduced plasma vWF levels 24 hrs after CLP surgery in mice given 100 μl of 100 μM Myr-SBD (~5 μM) as compared to mice treated with Myr-scrambled peptide. Furthermore, microvascular thrombosis of the kidney was strikingly reduced in mice treated with Myr-SBD compared to scrambled control and sham animals. Consistent with the hypothesis that Gα12-dependent increase in vWF secretion during sepsis leads to poor outcome, all WT mice succumbed to sepsis in less than 96 hrs whereas 100% of Gα12-/- mice shown previously to have significantly reduced plasma vWF levels survived. Thus, inhibition of Gα12/αSNAP dependent vWF secretion may be an effective strategy for blocking microvascular thrombosis, DIC, and death due to sepsis.
Author Disclosures: L. Rusu: None. M. Schlapfer: None. J. Atkinson: None. X. Du: None. R.D. Minshall: None.
- © 2014 by American Heart Association, Inc.