Abstract DP316: BB-031 inhibition of VWF in AIS: does it cast a large NETs?

Introduction: Acute ischemic stroke (AIS) is the leading cause of long-term disability. rtPA/TNK treatment results in intracranial hemorrhage (ICH) in ~7% of patients with ~40% mortality. Increased Neutrophil Extracellular Traps (NETs) correlate with ICH, and blood brain barrier (BBB) disruption. Von Willebrand Factor (VWF) induces thrombosis and inflammation in AIS. BB-031 aptamer targets VWF resulting in thrombolysis and BB-025 reverses BB-031. We hypothesize BB-031 will reduce NETs in canine thromboembolic middle cerebral artery occlusion (eMCAO), improving infarct volumes. Methods: Six hours after autologous canine eMCAO, animals received vehicle, 0.5, 1.0, or 5.0 mg/kg BB-031, or 0.5 mg/kg BB-031+0.5 mg/kg BB-025. Circulating neutrophil elastase (NE), citrullinated histone (CitH3), myeloperoxidase (MPO), VWF and modulator, ADAMTS13 levels were analyzed 3 hours after treatment at time of sacrifice. Results: Inflammatory markers at time of sacrifice VWF levels with 0.5 mg/kg (4.55 ± 1.38 ng/ml, n=8, p=.0068), 1.0 mg/kg 3.18 ± 1.33 ng/ml, n=4, p<.0001), and 5.0 mg/kg (3.06 ± .812 ng/ml, n=4, p=.0034) BB-031 were significantly lower than vehicle (5.96 ± 2.35 ng/ml, n=7) at time of sacrifice. Both 1.0 (56.89+/-4.73) and 5.0 mg/kg BB-031 (49.85+/-24.83) resulted in significantly lower CitH3 levels compared to vehicle (66.43+/-5.13, mg/ml, p<.05). 5.0 mg/kg BB-031 (0.5613+/-.2517) had significantly lower MPO levels than vehicle (.9948+/-.0284, ng/ml, p<.001) and 0.5 mg/kg BB-031(0.939+/-.149, p=.0122) or 1.0 BB-031 (0.871+/-.2732, p=.0335). This trend was duplicated in NE levels with significantly lower levels with 5.0 BB-031 (7.072+/-3.201 ng/ml) vs vehicle (24.52+/-.7.942, ng/ml, p<.001) and 0.5 mg/kg BB-031(24.06+/-7.970, ng/ml, p<.0001) or 1.0 BB-031 (31.88+/-10.95, ng/ml, p<.001). Reversal with BB-025 treatment was no significantly different than vehicle in any inflammatory infiltrate resultant levels. Conclusion: BB-031 resulted in a dose response effect with significantly lower levels of inflammatory markers with protracted canine eMCAO. Inflammatory infiltration after AIS provides additional targets with reperfusion after BB-031 thrombolysis outside the rtPA/TNK therapeutic window.