Mingchang Li

N-Acetyl-Serotonin Offers Neuroprotection through Inhibiting Mitochondrial Death Pathways and Autophagic Activation in Experimental Models of Ischemic Injury

N-acetylserotonin (NAS) is an immediate precursor of melatonin, which we have reported is neuroprotective against ischemic injury. Here we test whether NAS is a potential neuroprotective agent in experimental models of ischemic injury. We demonstrate that NAS inhibits cell death induced by oxygen–glucose deprivation or H2O2 in primary cerebrocortical neurons and primary hippocampal neurons in vitro, and organotypic hippocampal slice cultures ex vivo and reduces hypoxia/ischemia injury in the middle cerebral artery occlusion mouse model of cerebral ischemia in vivo. We find that NAS is neuroprotective by inhibiting the mitochondrial cell death pathway and the autophagic cell death pathway. The neuroprotective effects of NAS may result from the influence of mitochondrial permeability transition pore opening, mitochondrial fragmentation, and inhibition of the subsequent release of apoptogenic factors cytochrome c, Smac, and apoptosis-inducing factor from mitochondria to cytoplasm, and activation of caspase-3, -9, as well as the suppression of the activation of autophagy under stress conditions by increasing LC3-II and Beclin-1 levels and decreasing p62 level. However, NAS, unlike melatonin, does not provide neuroprotection through the activation of melatonin receptor 1A. We demonstrate that NAS reaches the brain subsequent to intraperitoneal injection using liquid chromatography/mass spectrometry analysis. Given that it occurs naturally and has low toxicity, NAS, like melatonin, has potential as a novel therapy for ischemic injury.

Hemorrhagic Transformation after Tissue Plasminogen Activator Reperfusion Therapy for Ischemic Stroke: Mechanisms, Models, and Biomarkers.

Intracerebral hemorrhagic transformation (HT) is well recognized as a common cause of hemorrhage in patients with ischemic stroke. HT after acute ischemic stroke contributes to early mortality and adversely affects functional recovery. The risk of HT is especially high when patients receive thrombolytic reperfusion therapy with tissue plasminogen activator, the only available treatment for ischemic stroke. Although many important publications address preclinical models of ischemic stroke, there are no current recommendations regarding the conduct of research aimed at understanding the mechanisms and prediction of HT. In this review, we discuss the underlying mechanisms for HT after ischemic stroke, provide an overview of the models commonly used for the study of HT, and discuss biomarkers that might be used for the early detection of this challenging clinical problem.

17β-estradiol attenuates breakdown of blood–brain barrier and hemorrhagic transformation induced by tissue plasminogen activator in cerebral ischemia

Tissue plasminogen activator (tPA) remains the only approved thrombolytic agent for the early treatment of ischemic stroke. However, treatment with tPA may lead to disruption of the blood-brain barrier and hemorrhagic transformation. 17β-estradiol (E2) has demonstrated efficacy in reduction of infarct volume in ischemic stroke models. The effects of acute administration of E2 on permeability of the blood-brain barrier and its ability to prevent hemorrhagic transformation in ischemic rats treated with tPA have not previously been studied. Here, we show that neurological deficits, brain water content, and Evans blue extravasation were increased in ovariectomized female Wistar rats treated with tPA and attenuated in rats receiving E2+tPA. We also show that intracerebral hemoglobin and matrix metalloproteinase-9 activity were elevated with tPA treatment, and these increases were reduced by E2 treatment. Taken together, these data demonstrate that acute administration of E2 is capable of ameliorating some of the adverse effects of tPA administration, including the increase of matrix metalloproteinase-9 activity, blood-brain barrier permeability, and hemorrhagic transformation. These findings suggest a potential role for estrogen in thrombolytic treatment for ischemic stroke.

Oncostatin M Confers Neuroprotection against Ischemic Stroke

Cell-surface receptors provide potential targets for the translation of bench-side findings into therapeutic strategies; however, this approach for the treatment of stroke is disappointing, at least partially due to an incomplete understanding of the targeted factors. Previous studies of oncostatin M (OSM), a member of the gp130 cytokine family, have been limited, as mouse models alone may not strongly resemble the human condition enough. In addition, the precise function of OSM in the CNS remains unclear. Here, we report that human OSM is neuroprotective in vivo and in vitro by recruiting OSMRβ in the setting of ischemic stroke. Using gain- and loss-of-function approaches, we demonstrated that decreased neuronal OSMRβ expression results in deteriorated stroke outcomes but that OSMRβ overexpression in neurons is cerebroprotective. Moreover, administering recombinant human OSM to mice before the onset of I/R showed that human OSM can be protective in rodent models of ischemic stroke. Mechanistically, OSM/OSMRβ activate the JAK2/STAT3 prosurvival signaling pathway. Collectively, these data support that human OSM may represent a promising drug candidate for stroke treatment. SIGNIFICANCE STATEMENT OSM, a member of the gp130 cytokine family, regulates neuronal function and survival. OSM engages a second receptor, either LIFRα or OSMRβ, before recruiting gp130. However, it is not clear whether OSM/OSMRβ signaling is involved in neuroprotection in the setting of ischemic stroke. Recent studies show that, compared with mouse disease models, the OSM receptor system in rats more closely resembles that in humans. In the present study, we use genetic manipulations of OSMRβ in both mouse and rat stroke models to demonstrate that OSMRβ in neurons is critical for neuronal survival during cerebral ischemic/reperfusion. Interestingly, administration of human OSM also leads to improved stroke outcomes. Therefore, OSM may represent a promising drug candidate for stroke treatment.

Methazolamide improves neurological behavior by inhibition of neuron apoptosis in subarachnoid hemorrhage mice

Subarachnoid hemorrhage (SAH) results in significant nerve dysfunction, such as hemiplegia, mood disorders, cognitive and memory impairment. Currently, no clear measures can reduce brain nerve damage. The study of brain nerve protection after SAH is of great significance. We aim to evaluate the protective effects and the possible mechanism of methazolamide in C57BL/6J SAH animal model in vivo and in blood-induced primary cortical neuron (PCNs) cellular model of SAH in vitro. We demonstrate that methazolamide accelerates the recovery of neurological damage, effectively relieves cerebral edema, and improves cognitive function in SAH mice as well as offers neuroprotection in blood- or hemoglobin-treated PCNs and partially restores normal neuronal morphology. In addition, western blot analyses show obviously decreased expression of active caspase-3 in methazolamide-treated SAH mice comparing with vehicle-treated SAH animals. Furthermore, methazolamide effectively inhibits ROS production in PCNs induced by blood exposure or hemoglobin insult. However, methazolamide has no protective effects in morality, fluctuation of cerebral blood flow, SAH grade, and cerebral vasospasm of SAH mice. Given methazolamide, a potent carbonic anhydrase inhibitor, can penetrate the blood–brain barrier and has been used in clinic in the treatment of ocular conditions, it provides potential as a novel therapy for SAH.

Tollip is a critical mediator of cerebral ischaemia–reperfusion injury

Toll‐like receptor (TLR) signalling plays an important role in regulating cerebral ischaemia–reperfusion (I/R) injury. Toll‐interacting protein (Tollip) is an endogenous negative modulator of TLR signalling that is involved in several inflammatory diseases. Our previous study showed that Tollip inhibits overload‐induced cardiac remodelling. However, the role of Tollip in neurological disease remains unknown. In the present study, we proposed that Tollip might contribute to the progression of stroke and confirmed this hypothesis. We found that Tollip expression was significantly increased in I/R‐challenged brain tissue of humans, mice and rats in vivo and in primary neurons subjected to oxygen and glucose deprivation in vitro, indicating the involvement of Tollip in I/R injury. Next, using genetic approaches, we revealed that Tollip deficiency protects mice against I/R injury by attenuating neuronal apoptosis and inflammation, as demonstrated by the decreased expression of pro‐apoptotic and pro‐inflammatory genes and the increased expression of anti‐apoptotic genes. By contrast, neuron‐specific Tollip over‐expression exerted the opposite effect. Mechanistically, the detrimental effects of Tollip on neuronal apoptosis and inflammation following I/R injury were largely mediated by the suppression of Akt signalling. Additionally, to further support our findings, a Tollip knockout rat strain was generated via CRISPR‐Cas9‐mediated gene inactivation. The Tollip‐deficient rats were also protected from I/R injury, based on dramatic decreases in neuronal apoptosis and ischaemic inflammation through Akt activation. Taken together, our findings demonstrate that Tollip acts as a novel modulator of I/R injury by promoting neuronal apoptosis and ischaemic inflammation, which are largely mediated by suppression of Akt signalling. Copyright

Multiple Intracranial Aneurysms Associated with Multiple Dural Arteriovenous Fistulas and Cerebral Arteriovenous Malformation

BACKGROUND The association between intracranial aneurysms and arteriovenous malformations (AVMs) or dural arteriovenous fistulas (DAVFs) has been well documented, and the changes in cerebral blood flow dynamics were thought to be one of the major causes. There has not been a report on intracranial aneurysms associated with multiple DAVFs and AVMs in the same patient. METHODS The authors report a unique case of multiple intracranial vascular pathologies, including 5 aneurysms, 2 DAVFs, and 1 AVM coexisting in a single patient. The patient presented with headache and left hemiparesis and was found to have 4 bilateral internal carotid aneurysms, 1 ruptured right pericallosal aneurysm, 2 frontoparietal DAVFs, and 1 right temporal AVM. RESULTS Endovascular coiling and Onyx embolization successfully occluded 4 aneurysms and both DAVFs. The patient remained asymptomatic at 1-year follow-up. CONCLUSIONS To our knowledge, this is the first report of a very rare case with a unique combination of cerebrovascular pathologies including multiple aneurysms, DAVFs, and 1 high-grade AVM. Analyzing the hemodynamic relationships of these concurrent lesions is essential to determine the hemorrhage risk of each lesion and the order of priority in management. Flow-related aneurysms with irregular morphology require early, aggressive treatment.

Vinexin-β deficiency protects against cerebral ischaemia/reperfusion injury by inhibiting neuronal apoptosis.

Vinexin‐β is an adaptor protein that regulates cell adhesion, cytoskeletal organization and signal transduction. Our previous work showed that Vinexin‐β protects against cardiac hypertrophy. However, its function in stroke is largely unknown. In the present study, we observed a significant increase in Vinexin‐β expression in both human intracerebral haemorrhage and mouse cerebral ischaemia/reperfusion (I/R) injury model, indicating that Vinexin‐β is involved in stroke. Next, using Vinexin‐β knockout mice, we further demonstrated that Vinexin‐β deficiency significantly protected against cerebral I/R injury, as demonstrated by a dramatic decrease in the infarct volume and an improvement in neurological function. Additionally, immunofluorescence and western blotting showed that the deletion of Vinexin‐β attenuated neuronal apoptosis. Mechanically, we found that Akt signalling was up‐regulated in the brains of the Vinexin‐β knockout mice compared with those of the WT control mice after ischaemic injury. Taken together, our results demonstrate that the deletion of Vinexin‐β potently protects against ischaemic injury by inhibiting neuronal apoptosis, and this effect may occur via the up‐regulation of Akt signalling. Our findings revealed that Vinexin‐β acts as a novel modulator of ischaemic injury, suggesting that Vinexin‐β may represent an attractive therapeutic target for the prevention of stroke. Vinexin‐β is an adaptor protein that regulates cell adhesion and cytoskeletal organization. We revealed that Vinexin‐β‐deficient mice are potently protected against ischaemia/reperfusion (I/R) injury. The protective effect is mediated through inhibiting neuronal apoptosis, which may occur via the up‐regulation of Akt signalling. These findings suggest Vinexin‐β as a novel regulator of I/R injury and attractive therapeutic target for the prevention of stroke.

LRIG1 enhances chemosensitivity by modulating BCL-2 expression and receptor tyrosine kinase signaling in glioma cells.

Purpose Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) are an inhibitor of receptor tyrosine kinases (RTKs) that was discovered in recent years, and many studies showed that LRIG1 is a tumor suppressor gene and may be related to tumor drug resistance. In this study, we explored whether LRIG1 protein expression can improve the chemosensitivity of glioma cells and what was its mechanism. Materials and Methods We collected 93 cases of glioma tissues and detected the expression of LRIG1 and BCL-2. We constructed a multidrug resistance cell line U251/multidrug resistance (MDR) and examined the change of LRIG1 and BCL-2 at mRNA and protein expression levels. LRIG1 expression was upregulated in U251/MDR cells and we detected the change of multidrug resistance. Meanwhile, we changed the expression of LRIG1 and BCL-2 and explored the relationship between LRIG1 and BCL-2. Finally, we also explored the relationship between LRIG1 and RTKs. Results LRIG1 was negatively correlated with BCL-2 expression in glioma tissue and U251/MDR cells, and upregulation of LRIG1 can enhance chemosensitivity and inhibit BCL-2 expression. Furthermore, LRIG1 was negatively correlated with RTKs in U251/MDR cells. Conclusion These results demonstrated that LRIG1 can improve chemosensitivity by modulating BCL-2 expression and RTK signaling in glioma cells.

What Sequences on High-Field MR Best Depict Temporal Resolution of Experimental ICH and Edema Formation in Mice?

Background and Purpose. Pilot study to examine the use of T1-, T2-, and T2*-weighted images for evaluating hematoma size and extent of edema in mouse brain at high field. Methods. Following collagenase-induced intracerebral hemorrhage, nine mice were imaged at 4.7 T using T1-, T2-, and T2*-weighted images for hematoma and edema quantitation on days 1, 3, 10, and 21 after surgery. Values were compared with morphometric analysis of cryosections at the time of final MR imaging. Results. For hematoma quantitation, the Spearman correlation coefficient (r) between T1 signal change and histology was 0.70 (P < 0.04) compared with r = 0.61 (P < 0.09) for T2*. The extent of perihematomal edema formation on cryosections was well reflected on T2 with r = 0.73 (P < 0.03). Conclusions. Within the limits of our pilot study, MR imaging on 4.7 T appears to approximate the temporal changes in hematoma and edema sizes in murine ICH well, thus laying the groundwork for longitudinal studies on hematoma resorption and edema formation.