Abstract 20799: Novel G Alpha 12 N-Terminal Alpha-SNAP Binding Domain Peptide Inhibits vWF Secretion, Prevents Microvascular Thrombosis and Increases Survival in Septic Mice
Introduction: Severe sepsis can be associated with a 2-3-fold increase in circulating active von Willebrand Factor (vWF)and thus is representative of the early vascular consequence of systemic inflammation and also a critical determinant of sepsis-induced microvascular thrombosis. Recently, we demonstrated that endogenous Gα12 promotes vWF secretion from Weibel Palade bodies by associating directly with α-SNAP via a portion of its unique N-terminal end, from which we synthesized a peptide, the αSNAP Binding Domain (SBD) antagonistic peptide.
Hypothesis and Research Design: In this study, we assess the hypothesis that SBD peptide can be titrated into activated endothelial cells in vivo to reduce vWF secretion evoked by inflammatory cytokines and disturbed flow in mice made septic by cecal ligation and puncture (CLP).
Results: Cellular uptake (8% of instilled) of a derivative of SBD peptide labelled with fluorescent 1-pyrenyuldiazomethane (PDAM) by cultured human endothelial cells, as well as blood and lung homogenate levels of PDAM-SBD peptide and blood clearance in rats were estimated by fluorometry. We found that a novel micellar (m) formulation of a cell-permeable form (Myristoylated) of SBD peptide (mMyr-SBD) as compared to Myr-scrambled peptide or vehicle only group (n=6 mice/group) reduced the level of plasma vWF 24 hrs after CLP surgery when given as a one-time i.v. bolus (80 μg/30 g mouse) at the time of surgery (p<0.05) . mMyr-SBD also prevented sepsis-induced thrombocytopenia (n=3/group), microvascular thrombosis associated with severe septicemia (kidney histology, n=3/group), and importantly, reduced mortality by 38% (n=10/group) without adversely causing hemorrhage ( mg Hb/mL saline; n=10 mice/group).Furthermore, control WT mice succumbed to sepsis in less than 96 hrs whereas 80% of Gα12-/- mice, shown previously to have significantly reduced plasma vWF levels, survived. In contrast, Gα12-/- mice that were subjected to CLP and injected i.v. with purified vWF (2 μg/g BW) exhibited mortality rates similar to WT mice.
Conclusions: We conclude that inhibition of Gα12/αSNAP dependent vWF secretion may be an effective strategy for blocking microvascular thrombosis, disseminated intravascular coagulation, and death due to sepsis.
Author Disclosures: L. Rusu: None. M. Bae: None. M. Castellon: None. A. Stojanovic-Terpo: None. J.W. Christman: None. X. Du: None. H. Onyuksel: None. R.D. Minshall: None.
- © 2016 by American Heart Association, Inc.