Ischemic Cerebroprotection Conferred by Myeloid Lineage-Restricted or Global CD39 Transgene Expression

Abstract

Background Cerebral tissue damage after an ischemic event can be exacerbated by inflammation and thrombosis. Elevated extracellular ATP and ADP levels are associated with cellular injury, inflammation and thrombosis. Ectonucleoside triphosphate diphosphohydrolase-1 (CD39), an enzyme expressed on the plasmalemma of leukocytes and endothelial cells, suppresses platelet activation and leukocyte infiltration by phosphohydrolyzing ATP/ADP. To investigate the effects of increased CD39 in an in vivo cerebral ischemia model, we developed a transgenic (TG) mouse expressing human CD39 (hCD39). Methods A floxed-stop sequence was inserted between the promoter and the hCD39 transcriptional start site, generating a mouse in which the expression of hCD39 can be controlled tissue-specifically, using Cre recombinase mice. We generated mice that express hCD39 globally or in myeloid-lineage cells only. Cerebral ischemia was induced by middle cerebral artery (MCA) occlusion. Infarct volumes were quantified by MRI after 48 hours. Results Both global and TG hCD39- and myeloid lineage (LysM) CD39-overexpressing mice (TG n=9, LysM n=6) demonstrated significantly smaller cerebral infarct volumes compared to wild type (WT) mice. Leukocytes from ischemic and contralateral hemispheres were analyzed by flow cytometry. While contralateral hemispheres had equal numbers of macrophages and neutrophils, ischemic hemispheres from TG mice had less infiltration (n=4). TG mice showed less neurologic deficit compared to WT mice (n=6). Conclusions This is the first report of transgenic overexpression of CD39 in mice imparting a protective phenotype following stroke, with reduced leukocyte infiltration, smaller infarct volumes, and decreased neurological deficit. CD39 overexpression, either globally or in myeloid lineage cells, quenches post-ischemic leukosequestration and reduces stroke-induced neurological injury.

Role of Purinergic Signalling in Endothelial Dysfunction and Thrombo-Inflammation in Ischaemic Stroke and Cerebral Small Vessel Disease

“…They found that the transgenic CD39 mice had decreased recruitment of macrophages and neutrophils, and overall decreased inflammation in the ischemic hemispheres. These mice also exhibited reduced neurological deficit and smaller infarct volumes, suggesting an overall therapeutic benefit of CD39 in stroke [123].…”

“…The therapeutic potential of CD39 in the ischemic brain was explored by Baek et al [123], who developed a transgenic mouse overexpressing human CD39 either globally or in myeloid-lineage cells only. They found that the transgenic CD39 mice had decreased recruitment of macrophages and neutrophils, and overall decreased inflammation in the ischemic hemispheres.…”

The post-cardiac arrest syndrome: A case for lung–brain coupling and opportunities for neuroprotection

“…In contrast to their vital role in defending against invading pathogens, neutrophils play a deleterious role in a broad range of non-infectious etiologies. [56][57][58] Clinical studies support that an elevated neutrophil to lymphocyte ratio at 48 and 72 h after cardiac arrest is associated with poor neurological outcome. 59 Similarly, elevated serum levels of the neutrophil-derived heparin-binding protein is a predictor of multiorgan failure.…”

Role of polymorphonuclear neutrophils in the reperfused ischemic brain: insights from cell-type-specific immunodepletion and fluorescence microscopy studies

“…Here, it was shown that PMN-expressed CD39 (a cell-surface adenosine triphosphatase) inhibits PMN invasion into the brain and hence leads to significantly reduced behavioral deficits in experimental stroke. 28 PMN depletion by anti-Ly6G antibody and blockade of PMN brain entry by anti-VLA-4 antibody consistently improved motor coordination deficits in mice exposed to transient intraluminal MCAO, as evaluated by a battery of motor coordination tests. 5 In contrast, T-cell depletion did not induce such motor coordination changes in the same study, despite reduction of brain infarct volume.…”

“…Here, it was shown that PMN-expressed CD39 (a cell-surface adenosine triphosphatase) inhibits PMN invasion into the brain and hence leads to significantly reduced behavioral deficits in experimental stroke. 28 …”