Stroke remains a leading cause of death and disability with limited therapeutic options. Endothelial cell β1 integrin receptors play a direct role in blood-brain barrier (BBB) dysfunction through regulation of tight junction proteins and infiltrating leukocytes, potentially mediated by β1 integrins. Following tandem transient common carotid artery/middle cerebral artery occlusion on wild-type mice, we administered the integrin a5b1 inhibitor, ATN-161, intraperitoneal (IP) injection at 1 mg/kg acutely after reperfusion, on post-stroke day (PSD)1 and PSD2. Systemic changes (heart rate, pulse distension, and body temperature) were determined. Additionally, infarct volume and edema were determined by 2,3-triphenyltetrazolium chloride and magnetic resonance imaging, while neurological changes were evaluated using an 11-point Neuroscore. Brain immunohistochemistry was performed for claudin-5, α5β1, IgG, and CD45 + cells, and quantitative polymerase chain reaction (qPCR) was performed for matrix metalloproteinase-9 (MMP-9), interleukin (IL)-1β, collagen IV, and CXCL12. ATN-161 significantly reduced integrin α5β1 expression in the surrounding peri-infarct region with no systemic changes. Infarct volume, edema, and functional deficit were significantly reduced in ATN-161-treated mice. Furthermore, ATN-161 treatment reduced IgG extravasation into the parenchyma through conserved claudin-5, collagen IV, CXCL12 while reducing MMP-9 transcription. Additionally, IL-1β and CD45 + cells were reduced in the ipsilateral cortex following ATN-161 administration. Collectively, ATN-161 may be a promising novel stroke therapy by reducing post-stroke inflammation and BBB permeability.

Inflammation is a major contributor to neuronal injury and is associated with poor outcome after acute brain injury such as stroke. The pro-inflammatory cytokine interleukin (IL)-1 is a critical regulator of cerebrovascular inflammation after ischemic injury, mainly through action of both of its isoforms, IL-1α and IL-1β, at the brain endothelium. In contrast, the differential action of these ligands on endothelial activation and post-stroke angiogenesis is largely unknown. Here we demonstrate that IL-1α is chronically elevated in the brain after experimental stroke suggesting that it is present during post-stroke angiogenic periods. Furthermore, we demonstrate that IL-1α is a potent mediator of endothelial activation and inducer of angiogenic markers in endothelial cells in vitro. Using brain endothelial cell lines, we found that IL-1α was significantly more potent than IL-1β at inducing endothelial cell activation, as measured by expression of the pro-angiogenic chemokine CXCL-1. IL-1α also induced strong expression of the angiogenic mediator IL-6 in a concentration-dependent manner. Furthermore IL-1α induced significant proliferation and migration of endothelial cells, and promoted formation of tube-like structures that are established key hallmarks of angiogenesis in vitro. Finally, all of those responses were blocked by the IL-1 receptor antagonist (IL-1RA). In conclusion, our data highlights a potential new role for IL-1 in brain repair mechanisms and identifies IL-1α as a potential new therapy to promote post-stroke angiogenesis.

We have developed a novel tissue banking protocol using mechanical thrombectomy to capture thrombus along with arterial blood proximal and distal to it. The protocol provides high-quality specimens, facilitating analysis of the initial molecular response to ischemic stroke in the human condition for the first time. This approach will permit reverse translation to animal models for treatment development.

BackgroundStroke remains a leading cause of death and disability worldwide despite recent treatment breakthroughs. A primary event in stroke pathogenesis is the development of a potent and deleterious local and peripheral inflammatory response regulated by the pro-inflammatory cytokine interleukin-1 (IL-1). While the role of IL-1β (main released isoform) has been well studied in stroke, the role of the IL-1α isoform remains largely unknown. With increasing utilization of intravenous tissue plasminogen activator (t-PA) or thrombectomy to pharmacologically or mechanically remove ischemic stroke causing blood clots, respectively, there is interest in pairing successful cerebrovascular recanalization with neurotherapeutic pharmacological interventions (Fraser et al., J Cereb Blood Flow Metab 37:3531–3543, 2017; Hill et al., Lancet Neurol 11:942–950, 2012; Amaro et al., Stroke 47:2874–2876, 2016).MethodsTransient stroke was induced in mice via one of two methods. One group of mice were subjected to tandem ipsilateral common carotid artery and middle cerebral artery occlusion, while another group underwent the filament-based middle cerebral artery occlusion. We have recently developed an animal model of intra-arterial (IA) drug administration after recanalization (Maniskas et al., J Neurosci Met 240:22–27, 2015). Sub groups of the mice were treated with either saline or Il-1α, wherein the drug was administered either acutely (immediately after surgery) or subacutely (on the third day after stroke). This was followed by behavioral and histological analyses.ResultsWe now show in the above-mentioned mouse stroke models (transient tandem ipsilateral common carotid artery (CCA) and middle cerebral artery occlusion (MCA) occlusion, MCA suture occlusion) that IL-1α is neuroprotective when acutely given either intravenously (IV) or IA at low sub-pathologic doses. Furthermore, while IV administration induces transient hemodynamic side effects without affecting systemic markers of inflammation, IA delivery further improves overall outcomes while eliminating these side effects. Additionally, we show that delayed/subacute IV IL-1α administration ameliorates functional deficit and promotes neurorepair.ConclusionsTaken together, our present study suggests for the first time that IL-1α could, unexpectedly, be an effective ischemic stroke therapy with a broad therapeutic window.

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