PB0299 - The dual neuroprotective and anti-inflammatory effects of acute constitutively active ADAMTS13 administration in preclinical models of intracerebral haemorrhage

Background: The acute management of stroke represents a critical challenge, as the urgency of intervention profoundly influences post-stroke outcomes. Hyperacute stroke management requires therapeutics that can be administered in pre-hospital settings, in the absence of a definite stroke subtype diagnosis. By degrading Von Willebrand Factor multimers, constitutively active (ca)ADAMTS13 (Ala1144Val variant) has shown great thrombolytic and anti-inflammatory properties in rodent models of ischaemic stroke. However, its effects on intracerebral haemorrhage (ICH) are currently unknown.

Aims: This study aims to elucidate the effects of caADAMTS13 administration in the context of ICH and explores its immunomodulatory properties on neutrophil infiltration into the brain.

Methods: Bubblehead zebrafish larvae were used as a model of spontaneous ICH. caADAMTS13 was administered acutely following ICH by intravenous microinjections. Live lightsheet microscopy was used to determine brain cell death (ubiq:secAnnexinV-mVenus) and neutrophils (mpo:GFP) in ICH+/- larvae treated with caADAMTS13 or vehicle. In mice, ICH was induced by injection of bacterial collagenase into the striatum. caADAMTS13 was administered 1hr post-bleeding onset and haematoma volume was assessed by T2 MRI scan. Two-way ANOVA followed by Tukey’s post-hoc test was used in analysis.

Results: Acute administration of caADAMTS13 in zebrafish embryos resulted in a significant reduction in ICH-induced brain cell death 24h post-treatment (n=34, **p=0.0033; Figure1). Beyond its neuroprotective properties, caADAMTS13 injection resulted in a marked reduction in brain neutrophil count 12h post-treatment, compared to vehicle-treated larvae (n=12, **p=0.0040; Figure2). Moreover, data from the murine model of ICH suggest that acute caADAMTS13 administration does not exacerbate haematoma expansion (n=4).

Conclusion(s): Acute administration of caADAMTS13 offers neuroprotection and reduces neutrophil migration to the brain following ICH in zebrafish. caADAMTS13 does not appear to exacerbate haematoma expansion in rodents, indicating that the treatment may not be detrimental to an ongoing haemorrhage. If safe for ICH patients, caADAMTS13 may potentially provide a more rapid treatment option for stroke.