Masafumi Toriyabe

Multiple therapeutic effects of progranulin on experimental acute ischaemic stroke

In the central nervous system, progranulin, a glycoprotein growth factor, plays a crucial role in maintaining physiological functions, and progranulin gene mutations cause TAR DNA-binding protein-43-positive frontotemporal lobar degeneration. Although several studies have reported that progranulin plays a protective role against ischaemic brain injury, little is known about temporal changes in the expression level, cellular localization, and glycosylation status of progranulin after acute focal cerebral ischaemia. In addition, the precise mechanisms by which progranulin exerts protective effects on ischaemic brain injury remains unknown. Furthermore, the therapeutic potential of progranulin against acute focal cerebral ischaemia, including combination treatment with tissue plasminogen activator, remains to be elucidated. In the present study, we aimed to determine temporal changes in the expression and localization of progranulin after ischaemia as well as the therapeutic effects of progranulin on ischaemic brain injury using in vitro and in vivo models. First, we demonstrated a dynamic change in progranulin expression in ischaemic Sprague-Dawley rats, including increased levels of progranulin expression in microglia within the ischaemic core, and increased levels of progranulin expression in viable neurons as well as induction of progranulin expression in endothelial cells within the ischaemic penumbra. We also demonstrated that the fully glycosylated mature secretory isoform of progranulin (∼88 kDa) decreased, whereas the glycosylated immature isoform of progranulin (58-68 kDa) markedly increased at 24 h and 72 h after reperfusion. In vitro experiments using primary cells from C57BL/6 mice revealed that the glycosylated immature isoform was secreted only from the microglia. Second, we demonstrated that progranulin could protect against acute focal cerebral ischaemia by a variety of mechanisms including attenuation of blood-brain barrier disruption, neuroinflammation suppression, and neuroprotection. We found that progranulin could regulate vascular permeability via vascular endothelial growth factor, suppress neuroinflammation after ischaemia via anti-inflammatory interleukin 10 in the microglia, and render neuroprotection in part by inhibition of cytoplasmic redistribution of TAR DNA-binding protein-43 as demonstrated in progranulin knockout mice (C57BL/6 background). Finally, we demonstrated the therapeutic potential of progranulin against acute focal cerebral ischaemia using a rat autologous thrombo-embolic model with delayed tissue plasminogen activator treatment. Intravenously administered recombinant progranulin reduced cerebral infarct and oedema, suppressed haemorrhagic transformation, and improved motor outcomes (P = 0.007, 0.038, 0.007 and 0.004, respectively). In conclusion, progranulin may be a novel therapeutic target that provides vascular protection, anti-neuroinflammation, and neuroprotection related in part to vascular endothelial growth factor, interleukin 10, and TAR DNA-binding protein-43, respectively.

Microglia preconditioned by oxygen-glucose deprivation promote functional recovery in ischemic rats

Cell-therapies that invoke pleiotropic mechanisms may facilitate functional recovery in stroke patients. We hypothesized that a cell therapy using microglia preconditioned by optimal oxygen-glucose deprivation (OGD) is a therapeutic strategy for ischemic stroke because optimal ischemia induces anti-inflammatory M2 microglia. We first delineated changes in angiogenesis and axonal outgrowth in the ischemic cortex using rats. We found that slight angiogenesis without axonal outgrowth were activated at the border area within the ischemic core from 7 to 14 days after ischemia. Next, we demonstrated that administration of primary microglia preconditioned by 18 hours of OGD at 7 days prompted functional recovery at 28 days after focal cerebral ischemia compared to control therapies by marked secretion of remodelling factors such as vascular endothelial growth factor, matrix metalloproteinase-9, and transforming growth factor-β polarized to M2 microglia in vitro/vivo. In conclusion, intravascular administration of M2 microglia preconditioned by optimal OGD may be a novel therapeutic strategy against ischemic stroke.

Spontaneous Middle Cerebral Artery Dissection Demonstrated by High-Resolution T1-Weighted 3D Image

Case Report A 39-year-old, right-handed man was admitted to our hospital because of sudden onset of right hemiparesis and aphasia. His medical history included atopic dermatitis, and included no episodes of trauma. He was alert on admission; however, his speech and comprehension were impaired, and was assessed a National Institutes of Health Stroke Scale score of 15. Brain computed tomography showed obscuration of the lentiform nucleus on the left side. Computed tomography angiography (CTA) demonstrated an occlusion of the left MCA at the horizontal segment. Laboratory examination yielded unremarkable results. Administration of intravenous recombinant tissue plasminogen activator (IV rtPA) was started at 164 min after symptom onset (alteplase, 0.6 mg/ kg). However, no neurological improvement was observed. Transcranial color-coded flow velocity measurements demonstrated reperfusion of the left MCA just after IV rt-PA administration, and 1.5T MRI detected an acute infarction in the left putamen, insular cortex, and corona radiata ( fig. 1 a). Magnetic resonance angiography results could not be evaluated because of motion artifacts. On day 4, CTA showed dilatation of the left MCA ( fig. 1 b) and the double lumen sign ( fig. 1 c), on the basis of which spontaneous MCAD was strongly suggested. However, atherothrombic occlusion, while unlikely given the circumstances, could not be completely ruled out at the time, since the fat-saturated T1-weighted imaging [4] needed to make an unambiguous diagnosis of MCAD was not performed. On day 17, fast spoiled gradient-echo images Spontaneous cervicocephalic arterial dissection is an uncommon cause of stroke [1] . Segments of the middle cerebral artery (MCA) are rarely involved, and the incidence of MCA dissection (MCAD) is reported to be 4% of the spontaneous cervicocephalic arterial dissections in Japan [2] . A previous report suggests that magnetic resonance imaging (MRI) may be useful for detecting intracranial vertebrobasilar artery dissection [3] , although the applicability in MCAD patients is unknown. Here, we report a patient who had MCAD with characteristic lesions, which was demonstrated by high-resolution T1-weighted 3D images obtained using a 3-tesla MRI (3T MRI) system. Published online: October 12, 2013

Effects of Alda-1, an Aldehyde Dehydrogenase-2 Agonist, on Hypoglycemic Neuronal Death

Hypoglycemic encephalopathy (HE) is caused by a lack of glucose availability to neuronal cells, and no neuroprotective drugs have been developed as yet. Studies on the pathogenesis of HE and the development of new neuroprotective drugs have been conducted using animal models such as the hypoglycemic coma model and non-coma hypoglycemia model. However, both models have inherent problems, and establishment of animal models that mimic clinical situations is desirable. In this study, we first developed a short-term hypoglycemic coma model in which rats could be maintained in an isoelectric electroencephalogram (EEG) state for 2 min and subsequent hyperglycemia without requiring anti-seizure drugs and an artificial ventilation. This condition caused the production of 4-hydroxy-2-nonenal (4-HNE), a cytotoxic aldehyde, in neurons of the hippocampus and cerebral cortex, and a marked increase in neuronal death as evaluated by Fluoro-Jade B (FJB) staining. We also investigated whether N-(1,3-benzodioxole-5-ylmethyl)-2,6-dichlorobenzamide (Alda-1), a small-molecule agonist of aldehyde dehydrogenase-2, could attenuate 4-HNE levels and reduce hypoglycemic neuronal death. After confirming that EEG recordings remained isoelectric for 2 min, Alda-1 (8.5 mg/kg) or vehicle (dimethyl sulfoxide; DMSO) was administered intravenously with glucose to maintain a blood glucose level of 250 to 270 mg/dL. Fewer 4-HNE and FJB-positive cells were observed in the cerebral cortex of Alda-1-treated rats than in DMSO-treated rats 24 h after glucose administration (P = 0.002 and P = 0.020). Thus, activation of the ALDH2 pathway could be a molecular target for HE treatment, and Alda-1 is a potentially neuroprotective agent that exerts a beneficial effect on neurons when intravenously administered simultaneously with glucose.