Reperfusion injury following cerebral ischemia: pathophysiology, MR imaging, and potential therapies

Neutrophil Membrane-Derived Nanovesicles Alleviate Inflammation To Protect Mouse Brain Injury from Ischemic Stroke

Ischemic stroke is an acute and severe neurological disease, resulting in disability and death. Reperfusion to an ischemic brain is a means to reverse brain damage after stroke; however, this causes secondary tissue damage induced by inflammation responses, called ischemia/reperfusion (I/R) injury. Adhesion of neutrophils to endothelial cells underlies the initiation of inflammation in I/R. Inspired by this interaction, we report a drug delivery system comprised of neutrophil membrane-derived nanovesicles loaded with Resolvin D2 (RvD2) that can enhance resolution of inflammation, thus protecting brain damage during ischemic stroke. In the study, the middle cerebral artery occlusion (MCAO) mouse model was developed to mimic ischemic stroke. Using intravital microscopy of a live mouse brain, we visualized the binding of nanovesicles to inflamed brain vasculature for delivery of therapeutics to ischemic stroke lesions in real-time. We also observed that RvD2-loaded nanovesicles dramatically decreased inflammation in ischemic stroke and improved mouse neurological functions. Our study provides a strategy to inhibit neuroinflammation using neutrophil-derived nanovesicles for ischemic stroke therapy.

Trametenolic acid B protects against cerebral ischemia and reperfusion injury through modulation of microRNA-10a and PI3K/Akt/mTOR signaling pathways

Trametenolic acid B (TAB) was a lanostane-type triterpenoid isolated from the trametes lactinea (Berk.) Pat. We have previously reported that extract from trametes lactinea (Berk.) Pat and TAB could efficiently improve learning and memory ability of the cerebral ischemia injury rats and suppress mitochondrial-mediated apoptosis in hydrogen peroxide damaged SH-SY5Y cells. However, the potential mechanisms have not been fully understood yet. The current study was to further investigate the protective effect of TAB on oxygen glucose deprivation/reoxygenation (OGD/R)-damaged SH-SY5Y cells and cerebral ischemia/reperfusion (I/R) injury rats, as well as its mechanisms involved. Cell experiments demonstrated that TAB (10, 20 and 40 μg/mL) protected OGD/R-induced SH-SY5Y cell injury by promoting cell proliferation and suppressing LDH leakage; Meanwhile, the results in vivo showed that TAB (20, 40 and 80 mg/kg) might significantly ameliorate the neurological deficit score, cerebral edema, neuronal cell loss and apoptosis, suppress cerebral infarction volume of the cerebral I/R injury rats. Further studies in vitro and in vivo indicated TAB could efficiently reduce OGD/R-damaged SH-SY5Y cell and cerebral I/R rat serum ROS, LDH and MDA levels, elevate SOD, GSH-Px and CAT activities, downregulate miR-10a mRNA and Bax, cytochrome C, cleaved-caspase-3 and cleaved-caspase-9 protein expressions, upregulate p-PIK3CA, p-Akt, p-mTOR, Bcl-2, pro-caspase-9 and pro-caspase-3 protein expressions and p-PIK3CA/PIK3CA, p-Akt/Akt, p-mTOR/mTOR ratios (P < 0.05 or P < 0.01, respectively). Our present study indicated that TAB possessed neuroprotective property against ODG/R and I/R injury by suppressing miR-10a expression, activating PI3K/Akt/mTOR signaling pathway, thereby reducing mitochondrial-mediated apoptosis, which provided a new insight for interpreting the underlying mechanisms of TAB' neuroprotective effect and a candidate agent to treat cerebral I/R injury.

Management of Blood Pressure During and After Recanalization Therapy for Acute Ischemic Stroke

Ischemic stroke is a common neurologic condition and can lead to significant long term disability and death. Observational studies have demonstrated worse outcomes in patients presenting with the extremes of blood pressure as well as with hemodynamic variability. Despite these associations, optimal hemodynamic management in the immediate period of ischemic stroke remains an unresolved issue, particularly in the modern era of revascularization therapies. While guidelines exist for BP thresholds during and after thrombolytic therapy, there is substantially less data to guide management during mechanical thrombectomy. Ideal blood pressure targets after attempted recanalization depend both on the degree of reperfusion achieved as well as the extent of infarction present. Following complete reperfusion, lower blood pressure targets may be warranted to prevent reperfusion injury and promote penumbra recovery however prospective clinical trials addressing this issue are warranted.

Protective Effects of Curcumin Against Ischemia-Reperfusion Injury in the Nervous System

Ischemia-reperfusion injury (I/R injury) is a common feature of ischemic stroke which occurs when blood supply is restored after a period of ischemia. Although stroke is an important cause of death in the world, effective therapeutic strategies aiming at improving neurological outcomes in this disease are lacking. Various studies have suggested the involvement of different mechanisms in the pathogenesis of I/R injury in the nervous system. These mechanisms include oxidative stress, platelet adhesion and aggregation, leukocyte infiltration, complement activation, blood-brain barrier (BBB) disruption, and mitochondria-mediated mechanisms. Curcumin, an active ingredient of turmeric, can affect all these pathways and exert neuroprotective activity culminating in the amelioration of I/R injury in the nervous system. In this review, we discuss the protective effects of curcumin against I/R injury in the nervous system and highlight the studies that have linked biological functions of curcumin and I/R injury improvement.

Amide proton transfer-weighted MRI can detect tissue acidosis and monitor recovery in a transient middle cerebral artery occlusion model compared with a permanent occlusion model in rats

OBJECTIVES

To assess whether increases in amide proton transfer (APT)-weighted signal reflect the effects of tissue recovery from acidosis using transient rat middle cerebral artery occlusion (MCAO) models, compared to permanent occlusion models.

MATERIALS AND METHODS

Twenty-four rats with MCAO (17 transient and seven permanent occlusions) were prepared. APT-weighted signal (APTw), apparent diffusion coefficient (ADC), cerebral blood flow (CBF), and MR spectroscopy were evaluated at three stages in each group (occlusion, reperfusion/1 h post-occlusion, and 3 h post-reperfusion/4 h post-occlusion). Deficit areas showing 30% reduction to the contralateral side were measured. Temporal changes were compared with repeated measures of analysis of variance. Relationship between APTw and lactate concentration was calculated.

RESULTS

Both APTw and CBF values increased and APTw deficit area reduced at reperfusion (largest p = .002) in transient occlusion models, but this was not demonstrated in permanent occlusion. No significant temporal change was demonstrated with ADC at reperfusion. APTw deficit area was between ADC and CBF deficit areas in transient occlusion model. APTw correlated with lactate concentration at occlusion (r = - 0.49, p = .04) and reperfusion (r = - 0.32, p = .02).

CONCLUSIONS

APTw values increased after reperfusion and correlated with lactate content, which suggests that APT-weighted MRI could become a useful imaging technique to reflect tissue acidosis and its reversal.

KEY POINTS

• APT-weighted signal increases in the tissue reperfusion, while remains stable in the permanent occlusion. • APTw deficit area was between ADC and CBF deficit areas in transient occlusion model, possibly demonstrating metabolic penumbra. • APTw correlated with lactate concentration during ischemia and reperfusion, indicating tissue acidosis.

Reperfusion Changes After Stroke and Practical Approaches for Neuroprotection

Reperfusion is the first line of care in a growing number of eligible acute ischemic stroke patients. Early reperfusion with thrombolytic drugs and endovascular mechanical devices is associated with improved outcome and lower mortality rates compared with natural history. Reperfusion is not without risk, however, and may result in reperfusion injury, which manifests in hemorrhagic transformation, brain edema, infarct progression, and neurologic worsening. In this article, the functional and structural changes and underlying molecular mechanisms of ischemia and reperfusion are reviewed. The pathways that lead to reperfusion injury and novel neuroprotective strategies with endogenous properties are discussed.

Scoparone protects neuronal cells from oxygen glucose deprivation/reoxygenation injury

Ischemic stroke is one of the leading causes of death and disability in the world. The cerebral ischemia/reperfusion (I/R) injury is considered as the major molecular mechanism in the pathogenesis of ischemic stroke. Scoparone, a major constituent of Artemisia capillaries, has been found to exhibit protective effects against I/R-induced myocardial injury. However, the role of scoparone in cerebral I/R injury has not been elucidated. In the current study, the hippocampal neurons were subjected to oxygen-glucose deprivation/reperfusion (OGD/R) to simulate I/R injury in vitro. The results showed that scoparone improved OGD/R-induced inhibitory effect on cell viability of hippocampal neurons. Scoparone displayed anti-oxidative activity as proved by the decreased levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and increased activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in OGD/R-induced hippocampal neurons. In addition, cell apoptosis was markedly decreased after scoparone treatment in OGD/R-induced hippocampal neurons. The expression of bax was significantly decreased, while bcl-2 expression was increased in the scoparone pretreated hippocampal neurons. Furthermore, the expressions of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were obviously induced by scoparone. Knockdown of Nrf2 by siRNA transfection dramatically attenuated the protective effects of scoparone on OGD/R-induced hippocampal neurons. Collectively, scoparone protected hippocampal neurons from OGD/R-induced injury via activating Nrf2/HO-1 signaling pathway, suggesting that scoparone might be a potential agent for the ischemic stroke therapy.

Ischemic stroke is one of the leading causes of death and disability in the world.

HSPB8 over-expression prevents disruption of blood-brain barrier by promoting autophagic flux after cerebral ischemia/reperfusion injury

Heat-shock protein B8 (HSPB8) has been recently reported to confer neuroprotection against ischemia/reperfusion (I/R)-induced cerebral injury in vivo and in vitro. However, the molecular mechanism is still elusive. This study focused on the effect of intracerebroventricular (i.c.v) delivery of lenti-HSPB8 virus against neurological injury in a rat model of cerebral I/R and explored the underlying mechanism. We found that lentivirus i.c.v injection-induced HSPB8 over-expression strongly alleviated infarct volume, improved neurobehavioral outcomes, and reduced brain edema in rat middle cerebral artery occlusion/reperfusion (MCAO/R) model. Concomitantly, HSPB8 over-expression noticeably prevented blood-brain barrier (BBB) disruption after cerebral I/R injury as indicated by the reduction in Evans blue leakage and IgG detection in the ipsilateral hemisphere compared with the vehicle group. Moreover, immunoblotting and immunofluorescence staining of tight junction proteins claudin-5 and occludin showed that HSPB8 over-expression prevented the degradation of these proteins induced by MCAO/R, which indicated the protective effect of HSPB8 on BBB. Western blotting and immunostaining techniques were also utilized to analyze the expression of the markers of autophagy. We found that HSPB8 over-expression promoted autophagic flux, evidenced by increased ratio of LC3 I/II, accumulation of Beclin-1 expression and enhanced p62 degradation. i.c.v injection of 15 μg autophagy inhibitor 3-methyladenine (3-MA) was applied at the onset of reperfusion. The results showed that 3-MA elicited a significant loss of the protective effect of HSPB8 against MCAO/R-induced neurological defect, Evans blue extravasation, and the loss tight junction proteins, suggesting that the BBB protective role of HSPB8 was, at least in part, mediated through autophagy. Collectively, HSPB8 may represent a potential therapeutic agent for preserving BBB integrity following cerebral I/R injury. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/. Cover Image for this issue: doi: 10.1111/jnc.14488.

Functional Expression of Organic Anion Transporting Polypeptide 1a4 Is Regulated by Transforming Growth Factor-β/Activin Receptor-like Kinase 1 Signaling at the Blood-Brain Barrier

Central nervous system (CNS) drug delivery can be achieved by targeting drug uptake transporters such as Oatp1a4. In fact, many drugs that can improve neurologic outcomes in CNS diseases [3-hydroxy-3-methylglutaryl-CoA reductase inhibitors (i.e., statins)] are organic anion transporting polypeptide (OATP) transport substrates. To date, transport properties and regulatory mechanisms of Oatp1a4 at the blood-brain barrier (BBB) have not been rigorously studied. Such knowledge is critical to develop Oatp1a4 for optimization of CNS drug delivery and for improved treatment of neurological diseases. Our laboratory has demonstrated that the transforming growth factor-β (TGF-β)/activin receptor-like kinase 1 (ALK1) signaling agonist bone morphogenetic protein 9 (BMP-9) increases functional expression of Oatp1a4 in rat brain microvessels. Here, we expand on this work and show that BMP-9 treatment increases blood-to-brain transport and brain exposure of established OATP transport substrates (i.e., taurocholate, atorvastatin, and pravastatin). We also demonstrate that BMP-9 activates the TGF-β/ALK1 pathway in brain microvessels as indicated by increased nuclear translocation of specific Smad proteins associated with signaling mediated by the ALK1 receptor (i.e., pSmad1/5/8). Furthermore, we report that an activated Smad protein complex comprised of phosphorylated Smad1/5/8 and Smad4 is formed following BMP-9 treatment and binds to the promoter of the Slco1a4 gene (i.e., the gene that encodes Oatp1a4). This signaling mechanism causes increased expression of Slco1a4 mRNA. Overall, this study provides evidence that Oatp1a4 transport activity at the BBB is directly regulated by TGF-β/ALK1 signaling and indicates that this pathway can be targeted for control of CNS delivery of OATP substrate drugs.

Roles of Nrf2/HO-1 and HIF-1α/VEGF in lung tissue injury and repair following cerebral ischemia/reperfusion injury

Cerebral ischemia/reperfusion injury (CIRI) leads to injury in distant organs, most commonly the lungs, although limited studies have examined self-protective mechanisms during CIRI-induced lung injury. Here, we investigated self-protective mechanisms that attenuate stress-related injury and promote the angiogenetic repair of epithelial function during CIRI-induced lung injury by measuring nuclear factor erythroid-related factor 2 (Nrf2) and hypoxia-inducible factor-1α (HIF-1α) levels. A CIRI model was established in male Sprague-Dawley rats by blocking the middle cerebral artery. Rats were divided into five subgroups based on the reperfusion time (6, 12, 24, 48, and 72 hr). Lung injury was assessed using a semiquantitative score and a thiobarbituric acid-based method of determining malonaldehyde production. Lung tissue angiogenesis was detected by CD34 and CD31 immunolabeling. Changes in Nrf2, heme oxygenase-1 (HO-1), HIF-1α, vascular-endothelial growth factor (VEGF), phosphatidylinositol 3-kinase (PI3K), extracellular-regulated kinase1/2 (ERK1/2), and phospho-ERK1/2 ( p-ERK1/2) protein- and mRNA-expression levels were measured by immunohistochemistry and reverse transcription polymerase chain reactions, respectively. Oxidative stress induced by cerebral ischemia/reperfusion (CI/R) caused lung injury. Expression of the Nrf2/HO-1 antioxidative stress pathway in lung tissues increased following CI/R, peaking after 24 hr. PI3K, ERK, and p-ERK1/2, which act upstream of Nrf2/HO-1, were expressed at higher levels in the CI/R-model group, consistent with the general trends observed for Nrf2/HO-1. Within 72 hr post-CI/R, HIF-1α, and VEGF expression significantly increased versus the sham group. Thus, during CIRI-induced lung injury, the body may upregulate antioxidative stress activities and promote angiogenesis to repair the endothelial barrier through the Nrf2/HO-1 and HIF-1α/VEGF signaling pathways, enabling self-protection.

Ischemic postconditioning confers cerebroprotection by stabilizing VDACs after brain ischemia

Ischemic postconditioning provides robust neuroprotection, therefore, determining the molecular events may provide promising targets for stroke treatment. Here, we showed that the expression of functional mitochondrial voltage-dependent anion channel proteins (VDAC1, VDAC2, and VDAC3) reduced in rat vulnerable hippocampal CA1 subfield after global ischemia. Ischemic postconditioning restored VDACs to physiological levels. Stabilized VDACs contributed to the benefits of postconditioning. VDAC1 was required for maintaining neuronal Ca²⁺ buffering capacity. We found that microRNA-7 (miR-7) was responsible for postischemic decline of VDAC1 and VDAC3. Notably, miR-7 was more highly expressed in the peripheral blood of patients with acute ischemic stroke compared to healthy controls. Inhibition of miR-7 attenuated neuronal loss and ATP decline after global ischemia, but also diminished the infarct volume with improved neurological functions after focal ischemia. Thus, ischemic postconditioning protects against mitochondrial damage by stabilizing VDACs. MiR-7 may be a potential therapeutic target for ischemic stroke.

Sensory stimulation in acute stroke therapy

The beneficial effects of cortical activation for functional recovery after ischemic stroke have been well described. However, little is known about the role of early sensory stimulation, i.e. stimulation during first 6 h after stroke onset even during acute treatment. In recent years, various preclinical studies reported significant effects of acute sensory stimulation that range from entire neuroprotection to increased infarct volumes by 30-50%. Systematic knowledge about the effect of acute sensory stimulation on stroke outcome is highly relevant as stroke patients are subject to uncontrolled sensory stimulation during transport, acute treatment, and critical care. This article discusses the current stage of knowledge about acute sensory stimulation and provides directions for future experimental and clinical trials.

Molecular Communication of a Dying Neuron in Stroke

When a main artery of the brain occludes, a cellular response involving multiple cell types follows. Cells directly affected by the lack of glucose and oxygen in the neuronal core die by necrosis. In the periphery surrounding the ischemic core (the so-called penumbra) neurons, astrocytes, microglia, oligodendrocytes, pericytes, and endothelial cells react to detrimental factors such as excitotoxicity, oxidative stress, and inflammation in different ways. The fate of the neurons in this area is multifactorial, and communication between all the players is important for survival. This review focuses on the latest research relating to synaptic loss and the release of apoptotic bodies and other extracellular vesicles for cellular communication in stroke. We also point out possible treatment options related to increasing neuronal survival and regeneration in the penumbra.

Inhibiting of GRASP65 Phosphorylation by DL-3-N-Butylphthalide Protects against Cerebral Ischemia-Reperfusion Injury via ERK Signaling

Background and Purpose

The aim of this study was to explore the role of DL-3-n-butylphthalide (NBP) in cerebral ischemia-reperfusion injury (CIRI) mice model. The involvement of extracellular signal-regulated kinase (ERK) signaling pathway was also investigated.

Methods

All mice were divided into five groups: sham-operated group, CIRI group, NBP pretreatment group, NBP treatment group, and NBP pretreatment + treatment group. The CIRI mice model was established by the use of the Pulsinelli four-vessel occlusion method. Pretreatment mice received NBP (90 mg/kg/d) three times a day within four days before reperfusion by gavage. Treatment mice received NBP (90 mg/kg/d) three times a day within five days after reperfusion by gavage. We detected the infarction area, the neurological severity, and the superoxide dismutase and malondialdehyde levels. Furthermore, we observed the expressions of GRASP65, phosphorylation of GRASP65 (pGRASP65), ERK, and phosphorylation of ERK (pERK) by the use of Western blotting.

Results

The result showed that the ERK pathway was activated in response to CIRI. NBP decreases the expressions of pERK and pGRASP65 following CIRI. Additionally, NBP could decrease MDA and increase SOD level in brain tissues. Decreased infarct volume was also observed in the NBP group. Thereby, NBP inhibited the activation of the ERK pathway induced by CIRI and reduced the GRASP65 phosphorylation.

Conclusions

The current finding suggested that NBP protected the cerebrum from CIRI mediated by inhibiting the ERK signaling pathway and subsequently reducing GRASP65 phosphorylation.

Improvement of memory and neurological deficit with Ocimum basilicum L. extract after ischemia reperfusion induced cerebral injury in mice

Oxidative stress is strongly implicated in the pathogenesis of stroke. Strategies using antioxidants to improve neurological functions after stroke have, thus, gained significant attention. Ocimum basilicum L. is used traditionally to treat CNS disorders. Its antioxidant capacity is well established. Our laboratory has reported protective effects of pre-treatment with O. basilicum in experimental stroke, but its curative (post-treatment) effects in ischemic stroke have not been documented. Hence, the present study was aimed to evaluate the effect of O. basilicum leaf extract (OBLE) on functional outcomes following cerebral injury in mice. Cerebral injury was induced in the experimental animals by bilateral common carotid artery occlusion (BCCAO) followed by reperfusion. OBLE treatment (200 and 400 mg/kg; orally, once daily) was given for 7 days after BCCAO. Cognitive outcomes and sensorimotor disturbances were evaluated with Morris Water Maze, Elevated Plus Maze and neurological severity score, respectively. TTC (2,3,5-triphenyltetrazolium chloride) staining was used to measure cerebral infarct size. Thiobarbituric acid reactive substances, reduced glutathione levels and superoxide dismutase activity in mice brain homogenate were estimated to elucidate the neuroprotective mechanism of OBLE. Treatment with OBLE resulted in marked improvement in memory and motor coordination. OBLE also decreased cerebral infarct size and oxidative stress in mice. The extract was standardised with respect to total phenol content; an HPLC-PDA analysis showed the presence of eight phenolic acids in OBLE. It is concluded that treatment with OBLE improves functional outcomes after ischemic stroke and this may be developed as a neuroprotective drug.

Danhong Injection Reversed Cardiac Abnormality in Brain-Heart Syndrome via Local and Remote β-Adrenergic Receptor Signaling

Ischemic brain injury impacts cardiac dysfunction depending on the part of the brain affected, with a manifestation of irregular blood pressure, arrhythmia, and heart failure. Generally called brain–heart syndrome in traditional Chinese medicine, few mechanistic understanding and treatment options are available at present. We hypothesize that considering the established efficacy for both ischemic stroke and myocardial infarction (MI), Danhong injection (DHI), a multicomponent Chinese patent medicine, may have a dual pharmacological potential for treating the brain–heart syndrome caused by cerebral ischemic stroke through its multi-targeted mechanisms. We investigated the role of DHI in the setting of brain–heart syndrome and determined the mechanism by which it regulates this process. We induced Ischemia/Reperfusion in Wistar rats and administered intravenous dose of DHI twice daily for 14 days. We assessed the neurological state, infarct volume, CT scan, arterial blood pressure, heart rhythm, and the hemodynamics. We harvested the brain and heart tissues for immunohistochemistry and western blot analyses. Our data show that DHI exerts potent anti-stroke effects (infarct volume reduction: ^∗∗p < 0.01 and ^∗∗∗p < 0.001 vs. vehicle. Neurological deficit correction: ^∗p < 0.05 and ^∗∗∗p < 0.001 vs. vehicle), and effectively reversed the abnormal arterial pressure (^∗p < 0.05 vs. vehicle) and heart rhythm (^∗∗p < 0.01 vs. vehicle). The phenotype of this brain–heart syndrome is strikingly similar to those of MI model. Quantitative assessment of hemodynamic in cardiac functionality revealed a positive uniformity in the PV-loop after administration with DHI and valsartan in the latter. Immunohistochemistry and western blot results showed the inhibitory effect of DHI on the β-adrenergic pathway as well as protein kinase C epsilon (PKCε) (^∗∗p < 0.01 vs. model). Our data showed the underlying mechanisms of the brain–heart interaction and offer the first evidence that DHI targets the adrenergic pathway to modulate cardiac function in the setting of brain–heart syndrome. This study has made a novel discovery for proper application of the multi-target DHI and could serve as a therapeutic option in the setting of brain–heart syndrome.

l-Homocarnosine attenuates inflammation in cerebral ischemia-reperfusion injury through inhibition of nod-like receptor protein 3 inflammasome

We investigated the therapeutic effects of l-homocarnosine against inflammation in a rat model of cerebral ischemia-reperfusion injury. Rats were grouped into control, middle cerebral artery occlusion (MCAO), 0.5 mM l-homocarnosine + MCAO, and 1 mM l-homocarnosine + MCAO treatment groups. Superoxide dismutase (SOD), glutathione peroxidase (Gpx), catalase, lipid peroxidation, and reduced glutathione (GSH) levels were measured. Neurological scores were assessed, and histopathology, scanning electron microscopy (SEM), and fluorescence microscopy analyses were conducted. The mRNA expression levels of nod-like receptor protein 3 (NLRP3), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) and protein expression levels of NLRP3 were assessed. l-Homocarnosine supplementation substantially increased SOD, catalase, Gpx, and GSH levels, whereas it reduced the levels of lipid peroxidation relative to MCAO rats. l-Homocarnosine significantly reduced the infarct area and neurological deficit score, as well as histopathological alteration, apoptosis, and necrosis in brain tissue. The mRNA expression levels of NLRP3, TNF-α, and IL-6 were increased in MCAO rats, whereas l-homocarnosine supplementation reduced mRNA expression by >40%, and NLRP3 protein expression was reduced by >30% in 1 mM l-homocarnosine-treated MCAO rats. We propose that l-homocarnosine exerts a protective effect in cerebral ischemia-reperfusion injury-induced rats by downregulating NLRP3 expression.

Neuroprotective effect of p-coumaric acid in mice with cerebral ischemia reperfusion injuries

Cerebral ischemia reperfusion (IR) is associated with neuronal death, which leads to disability and cognitive decline. The pathomechanism occurs because ischemia is exacerbated during the reperfusion period. Neuronal damage susceptibility depends on the affected brain areas and the duration of ischemia. Prevention and supplementation to neurons may help them endure during IR and further benefit them in rehabilitation. We investigated the protective effect of p-coumaric acid (PC) on cerebral IR injuries in mice. We randomly divided 30 male ICR mice into 3 groups of Sham (received vehicle and not induced IR), Control-IR (received vehicle and induced IR) and PC-IR (received 100 mg/kg PC and induced IR). We orally administered vehicle or 100 mg/kg of p-coumaric acid for 2 weeks before inducing the cerebral IR injuries by using 30 min of a bilateral common carotid artery occlusion followed by a 45-min reperfusion. We induced the IR condition in the Control-IR and PC-IR groups but not the Sham group, and only the PC-IR group received p-coumaric acid. After IR induction, we sacrificed all the mice and collected their brain tissues to evaluate their oxidative statuses, whole brain infarctions and vulnerable neuronal deaths. We studied the whole-brain infarction volume by 2, 3, 5-triethyltetrazoliumchloride staining of sections. We performed a histological investigation of the vulnerable neuronal population in the dorsal hippocampus by staining brain sections with 0.1% cresyl violet. The results indicated that IR caused significant increases in calcium and malondialdehyde (MDA) levels, whole brain infarction volume and hippocampal neuronal death. Pretreatment with p-coumaric acid significantly reduced MDA levels, whole-brain infarction volume and hippocampal neuronal death together and increased catalase and superoxide dismutase activities. We conclude here that pretreating animals with p-coumaric acid can prevent IR-induced brain oxidative stress, infarction size and neuronal vulnerability to death in cerebral IR injuries.

Lung Ischaemia-Reperfusion Injury: The Role of Reactive Oxygen Species

Lung ischaemia-reperfusion injury (LIRI) occurs in many lung diseases and during surgical procedures such as lung transplantation. The re-establishment of blood flow and oxygen delivery into the previously ischaemic lung exacerbates the ischaemic injury and leads to increased microvascular permeability and pulmonary vascular resistance as well as to vigorous activation of the immune response. These events initiate the irreversible damage of the lung with subsequent oedema formation that can result in systemic hypoxaemia and multi-organ failure. Alterations in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been suggested as crucial mediators of such responses during ischaemia-reperfusion in the lung. Among numerous potential sources of ROS/RNS within cells, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, xanthine oxidases, nitric oxide synthases and mitochondria have been investigated during LIRI. Against this background, we aim to review here the extensive literature about the ROS-mediated cellular signalling during LIRI, as well as the effectiveness of antioxidants as treatment option for LIRI.

Combined Treatment With Dichloroacetic Acid and Pyruvate Reduces Hippocampal Neuronal Death After Transient Cerebral Ischemia

Transient cerebral ischemia (TCI) occurs when blood flow to the brain is ceased or dramatically reduced. TCI causes energy depletion and oxidative stress, which leads to neuronal death and cognitive impairment. Dichloroacetic acid (DCA) acts as an inhibitor of pyruvate dehydrogenase kinase (PDK). Additionally, DCA is known to increase mitochondrial pyruvate uptake and promotes glucose oxidation during glycolysis, thus enhancing pyruvate dehydrogenase (PDH) activity. In this study, we investigated whether the inhibition of PDK activity by DCA, which increases the rate of pyruvate conversion to adenosine triphosphate (ATP), prevents ischemia-induced neuronal death. We used a rat model of TCI, which was induced by common carotid artery occlusion and hypovolemia for 7 min while monitoring the electroencephalography for sustained isoelectric potential. Male Sprague-Dawley rats were given an intraperitoneal injection of DCA (100 mg/kg) with pyruvate (50 mg/kg) once per day for 2 days after insult. The vehicle, DCA only or pyruvate on rats was injected on the same schedule. Our study demonstrated that the combined administration of DCA with pyruvate significantly decreased neuronal death, oxidative stress, microglia activation when compared with DCA, or pyruvate injection alone. These findings suggest that the administration of DCA with pyruvate may enhance essential metabolic processes, which in turn promotes the regenerative capacity of the post-ischemic brain.

Complete Restitution of the Ischemic Penumbra after Successful Thrombectomy : A Pilot Study Using Quantitative MRI

PURPOSE

Endovascular thrombectomy is highly effective in patients with proximal large artery occlusion but the relevance of reperfusion injury after recanalization is a matter of debate. The aim of this study was to investigate potential residual metabolic distress and microstructural tissue damage or edema after reperfusion using quantitative oxygen-sensitive T2' and T2-mapping in patients successfully treated by thrombectomy.

METHODS

Included in this study were 11 patients (mean age 70 ± 11.4 years) with acute ischemic stroke due to internal carotid artery and/or middle cerebral artery occlusion. Quantitative T2 and T2' (1/T2' = 1/T2* - 1/T2) were determined within the ischemic core and hypoperfused but salvaged tissue with delayed time-to-peak (TTP) in patients before and after successful thrombectomy and compared to a control region within the unaffected hemisphere.

RESULTS

Decreased T2' values within hypoperfused tissue before thrombectomy showed a normalization after recanalization (p < 0.01). In formerly hypoperfused but salvaged tissue, T2 values increased significantly after thrombectomy (p < 0.05) but did not differ from reference values in the control region. In salvaged tissue, increases of quantitative T2' and T2 to follow-up were more pronounced in areas with severe TTP delay.

CONCLUSION

After successful recanalization, T2' re-increased back to normal in formerly hypoperfused areas as a sign of prompt normalization of oxygen metabolism. Furthermore, quantitative T2 in the formerly hypoperfused tissue did not differ from reference values in unaffected tissue. These results indicate complete restitution of salvaged tissue after reperfusion and support the overall safety of endovascular thrombectomy with respect to microstructural tissue integrity.

Microbubbles combined with ultrasound therapy in ischemic stroke: A systematic review of in-vivo preclinical studies

BACKGROUND

Microbubbles (MBs) combined with ultrasound sonothrombolysis (STL) appears to be an alternative therapeutic strategy for acute ischemic stroke (IS), but clinical results remain controversial.

OBJECTIVE

The aim of this systematic review is to identify the parameters tested; to assess evidence on the safety and efficacy on preclinical data on STL; and to assess the validity and publication bias.

METHODS

Pubmed® and Web of ScienceTM databases were systematically searched from January 1995 to April 2017 in French and English. We included studies evaluating STL on animal stroke model. This systematic review was conducted in accordance with the PRISMA guidelines. Data were extracted following a pre-defined schedule by two of the authors. The CAMARADES criteria were used for quality assessment. A narrative synthesis was conducted.

RESULTS

Sixteen studies met the inclusion criteria. The result showed that ultrasound parameters and types of MBs were heterogeneous among studies. Numerous positive outcomes on efficacy were found, but only four studies demonstrated superiority of STL versus recombinant tissue-type plasminogen activator on clinical criteria. Data available on safety are limited.

LIMITATIONS

Quality assessment of the studies reviewed revealed a number of biases.

CONCLUSION

Further in vivo studies are needed to demonstrate a better efficacy and safety of STL compared to currently approved therapeutic options.

SYSTEMATIC REVIEW REGISTRATION

http://syrf.org.uk/protocols/.

Free Radical Damage in Ischemia-Reperfusion Injury: An Obstacle in Acute Ischemic Stroke after Revascularization Therapy

Acute ischemic stroke is a common cause of morbidity and mortality worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury after revascularization therapy can result in worsening outcomes. Among all possible pathological mechanisms of ischemia-reperfusion injury, free radical damage (mainly oxidative/nitrosative stress injury) has been found to play a key role in the process. Free radicals lead to protein dysfunction, DNA damage, and lipid peroxidation, resulting in cell death. Additionally, free radical damage has a strong connection with inducing hemorrhagic transformation and cerebral edema, which are the major complications of revascularization therapy, and mainly influencing neurological outcomes due to the disruption of the blood-brain barrier. In order to get a better clinical prognosis, more and more studies focus on the pharmaceutical and nonpharmaceutical neuroprotective therapies against free radical damage. This review discusses the pathological mechanisms of free radicals in ischemia-reperfusion injury and adjunctive neuroprotective therapies combined with revascularization therapy against free radical damage.

[The efficacy of prevention of postoperative cognitive dysfunction in cardiac surgeries with the use of the cerebrolysin]

AIM

To assess the efficacy of postoperative cytoprotection with cerebrolysin in cardiac surgeries without using cardiopulmonary bypass and to analyze the changes in the blood circulation in the postoperative period in groups with- and without cerebrolysin preconditioning.

MATERIAL AND METHODS

Thirty-eight patients, who underwent coronary and mammaro-coronary bypass grafting without using cardiopulmonary bypass, were included in the study. Fifteen patients received cerebrolysin before surgery.

RESULTS AND CONCLUSION

Cerebrolysin improved cognitive test scores. Positive changes on anxiety and depression scales were observed as well. In the group of patients treated with cerebrolysin, quantitative parameters of the cerebral blood flow were in stable condition, with a slight increase on the 10th day after surgery, which may indicate increasing stress resistance of cells of the central nervous system after appropriate pharmacological protection.

A novel IL-1RA-PEP fusion protein alleviates blood-brain barrier disruption after ischemia-reperfusion in male rats

BACKGROUND

Current options to treat clinical relapse in inflammatory central nervous system (CNS) conditions such as cerebral ischemia-reperfusion injury are limited, and agents that are more effective are required. Disruption of the blood-brain barrier is an early feature of lesion formation that correlates with clinical exacerbation and facilitates the entry of inflammatory medium and inflammatory cells. Interleukin-1 receptor antagonist (IL-1RA) is a naturally occurring anti-inflammatory antagonist of the interleukin-1 (IL-1) family. The broad-spectrum anti-inflammatory effects of IL-1RA have been investigated against various forms of neuroinflammation. However, the effect of IL-1RA on blood-brain barrier disruption following ischemia-reperfusion has not been reported.

METHODS

In this study, we investigated the effects of IL-1RA and a novel protein (IL-1RA-PEP) that was fused to IL-1RA with a cell penetrating peptide, on blood-brain barrier integrity, in male rats subjected to transient middle cerebral artery occlusion.

RESULTS

After intravenous administration, IL-1RA-PEP (50 mg/kg) penetrated cerebral tissues more effectively than IL-1RA. Moreover, it preserved blood-brain barrier integrity, attenuated changes in expression and localization of tight junction proteins and matrix metalloproteinases, and enhanced angiogenesis in ischemic brain tissue. Further study suggested that the effects of IL-1RA-PEP on preserving blood-brain barrier integrity might be closely correlated with the p65/NF-κB pathway, as evidenced by the effects of the inhibitor JSH-23.

CONCLUSIONS

Collectively, our results demonstrated that IL-1RA-PEP could effectively penetrate the brain of rats with middle cerebral artery occlusion and ameliorate blood-brain barrier disruption. This finding might represent its novel therapeutic potential in the treatment of the cerebral ischemia-reperfusion injury.

Oncotic Cell Death in Stroke

Oncotic cell death or oncosis represents a major mechanism of cell death in ischaemic stroke, occurring in many central nervous system (CNS) cell types including neurons, glia and vascular endothelial cells. In stroke, energy depletion causes ionic pump failure and disrupts ionic homeostasis. Imbalance between the influx of Na⁺ and Cl^- ions and the efflux of K⁺ ions through various channel proteins and transporters creates a transmembrane osmotic gradient, with ensuing movement of water into the cells, resulting in cell swelling and oncosis. Oncosis is a key mediator of cerebral oedema in ischaemic stroke, contributing directly through cytotoxic oedema, and indirectly through vasogenic oedema by causing vascular endothelial cell death and disruption of the blood-brain barrier (BBB). Hence, inhibition of uncontrolled ionic flux represents a novel and powerful strategy in achieving neuroprotection in stroke. In this review, we provide an overview of oncotic cell death in the pathology of stroke. Importantly, we summarised the therapeutically significant pathways of water, Na⁺, Cl^- and K⁺ movement across cell membranes in the CNS and their respective roles in the pathobiology of stroke.

The Role of Circular RNAs in Cerebral Ischemic Diseases: Ischemic Stroke and Cerebral Ischemia/Reperfusion Injury

Cerebral ischemic diseases including ischemic stroke and cerebral ischemia reperfusion injury can result in serious dysfunction of the brain, which leads to extremely high mortality and disability. There are no effective therapeutics for cerebral ischemic diseases to date. Circular RNAs are a kind of newly investigated noncoding RNAs. It is reported that circular RNAs are enriched in multiple organs, especially abundant in the brain, which indicates that circular RNAs may be involved in cerebral physiological and pathological processes. In this chapter, we will firstly review the pathophysiology, underlying mechanisms, and current treatments of cerebral ischemic diseases including ischemic stroke and cerebral ischemia/reperfusion injury. Secondly, the characteristics and function of circular RNAs will be outlined, and then we are going to introduce the roles circular RNAs play in human diseases. Finally, we will summarize the function of circular RNAs in cerebral ischemic diseases.

Neuroprotective Effect of Curcumin Against Cerebral Ischemia-Reperfusion Via Mediating Autophagy and Inflammation

Curcumin, a polyphenolic compound extracted from Curcuma longa, has drawn attention for its effective bioactivities against ischemia-induced injury. This study aimed to evaluate the neuroprotective effect of curcumin and investigate the underlying mechanism that mediates autophagy and inflammation in an animal model of middle cerebral artery occlusion (MCAO) in rats. Curcumin was delivered to Sprague Dawley male rats at a dose of 200 mg/kg curcumin by intraperitoneal injection 30 min after ischemia-reperfusion (I/R). LY294002, a specific inhibitor of the PI3K/Akt/mTOR pathway, as well as anisomycin, an activator of TLR4/p38/MAPK, was administered by ventricle injection 30 min before MCAO. The same volume of saline was given as a control. Brain infarction and neurological function were determined 24 h post-MCAO. Immunoblotting and immunofluorescence were used to detect alterations in autophagy-relevant proteins Akt, p-Akt, mTOR, p-mTOR, LC3-II, and LC3-I, and inflammation-related proteins TLR4, p-38, p-p38, and IL-1 in the ipsilateral hemisphere. Cerebral I/R injury resulted in significant alterations of LC3-II/LC3-I, IL-1, TLR4, and p-p38. Curcumin in MCAO rats significantly improved brain damage and neurological function by upregulating p-Akt and p-mTOR and downregulating LC3-II/LC3-I, IL-1, TLR4, p-38, and p-p38. However, these protective effects against ischemia could be suppressed when LY294002 or anisomycin was included. Curcumin exerts neuroprotective effects by attenuating autophagic activities through mediating the PI3K/Akt/mTOR pathway, while also suppressing an inflammatory reaction by regulating the TLR4/p38/MAPK pathway. Furthermore, this study indicates that curcumin could be an effective therapy for patients afflicted with ischemia.

Profiling neuron-autonomous lncRNA changes upon ischemia/reperfusion injury

Extensive changes of neuronal transcriptome occur post ischemic stroke and during the following reperfusion. Although numerous studies focused on transcriptome changes of mRNAs associated with ischemic stroke, little is known about whether and how long non-coding RNAs (lncRNAs), which play critical roles in cellular homeostasis, are involved in this process. In this study, we performed high throughput screening to analyze expression changes of lncRNAs in primarily cultured hippocampal neurons under an oxygen-glucose deprivation/reperfusion (OGD/R) condition at 0 h, 6 h, 12 h, and 18 h, respectively. Knock down of one validated lncRNAs (Tnxa-ps1) promoted neuronal survival by inhibiting apoptosis. Coding non-coding co-expression network analysis revealed that the expression of Tnxa-ps1 was highly correlated with changes of a particular group of genes, many of which are associated with neural protection. Finally, we showed that down-regulation of Tnxa-ps1 reversed the expression changes of four mRNAs post OGD/R, revealing a regulatory effect between Tnxa-ps1 and selected genes. Together, our data revealed possible participation of lncRNAs in the pathophysiology of OGD/R and thereby provided new insights into the studies of potential therapeutic targets for ischemic stroke.

Role of HIF-1a in regulating autophagic cell survival during cerebral ischemia reperfusion in rats

Hypoxia-inducible factor-1a (HIF-1a) plays a beneficial role during cerebral ischemia reperfusion (IR), but the underlying molecular mechanisms are not completely understood. Here, we aimed to investigate the effects and molecular regulation of HIF-1a on brain cell apoptosis and autophagy during IR. We found that augmentation of HIF-1a in re-perfused hematopoietic cells significantly reduced brain damage, alleviated brain edema and improved neural function during IR, seemingly through two HIF-1a target genes BNIP3 and NIX, which were critical regulators for cell apoptosis and autophagic cell survival. in vitro, HIF-1a induced up-regulation of BNIP3 and NIX in human cortical neuron cells, HCN-1A. Inhibition of BNIP3 and NIX significantly attenuated HIF-1a-suppressed cell apoptosis and HIF-1a-induced cell autophagy. Together, these data suggest that HIF-1a may ameliorate brain damages during IR through BNIP3 and NIX -dependent augmentation of autophagic cell survival and reduction in cell apoptosis.

Subacute endovascular recanalization of symptomatic cerebral artery occlusion: a propensity score-matched analysis

BACKGROUND

The interval between the onset of cerebral vessel occlusion and recanalization has been shown to be an independent predictor of poor outcomes. However, endovascular recanalization of symptomatic cerebral vessel occlusion in the subacute period has not been well documented. We investigated the safety and efficacy of subacute recanalization of occluded cerebral vessels in patients with ischemic stroke or transient ischemic attacks (TIAs).

METHODS

Between 2014 and 2015, 98 patients were admitted to the emergency room for ischemic stroke or TIA with a small infarct core, which was defined as modest early ischemic change on non-contrast CT or overt diffusion-perfusion mismatch. All patients underwent pre-transfemoral cerebral angiography and post-endovascular treatment. The patients were classified according to acute (onset-to-groin puncture time ≤6 hours) or subacute (onset-to-groin puncture time >6 hours) recanalization. Using propensity score analysis, recipients of acute and subacute recanalization underwent 1:1 matching.

RESULTS

Following 1:1 propensity score matching, 32 patients who underwent acute and 32 who underwent subacute intra-arterial thrombolysis were matched. There were no significant differences in National Institutes of Health Stroke Scale at discharge, modified Rankin scale (mRS), the proportion of patients with an mRS value of 0-2, mortality at discharge, intracerebral bleeding, postprocedural infarct extension, newly detected infarction, and hyperintense acute reperfusion marker on follow-up images between the acute and subacute recanalization groups.

CONCLUSIONS

In selected patients with clinically unstable cerebral artery occlusions, a diffusion-perfusion mismatch and small CT lesions, subacute and acute recanalization has comparable safety and efficacy rates.

Characterisation of a mouse cerebral microvascular endothelial cell line (bEnd.3) after oxygen glucose deprivation and reoxygenation

Studies have utilised immortalised mouse cerebral endothelial cells (bEnd.3) exposed to oxygen glucose deprivation (OGD) to study blood-brain barrier (BBB) disruption after ischaemia. However, there is a paucity of literature describing the duration of OGD (and reoxygenation [RO]) required to best simulate BBB disruption in vivo. In this study we assessed BBB disruption in bEnd.3 cells after exposure to a range of OGD periods, and also after OGD + RO. Exposure of bEnd.3 monolayers to 4, 6, 16, or 24 hours of OGD resulted in a significant increase in permeability. The hyperpermeability after 16 or 24 hours was associated with decreased expression of tight junction proteins (occludin and claudin-5). Furthermore, there was a decrease in cell viability and increased expression of the pro-apoptotic protein, cleaved caspase-3. Exposure of bEnd.3 monolayers to 1 hour OGD+ 23 hours RO exacerbated hyperpermeability relative to 1 hour OGD, which was associated with decreased expression levels of occludin and ZO-1, but no change in cell viability or caspase-3. 4 hours OGD + 23 hours RO exacerbated hyperpermeability, decreased expression levels of tight junction proteins, decreased cell viability, and increased caspase-3 expression. Thus, bEnd.3 cells exhibit hyperpermeability, a loss of tight junction proteins, and undergo cell death, after exposure to prolonged periods of OGD. Moreover, they exhibit exacerbated hyperpermeability, a loss of tight junction proteins, and increased expression of caspase-3 after OGD + RO. These findings will facilitate the use of this cell line in studies of BBB disruption and for the testing of therapeutics.

A Meta-Analysis of Observational Evidence for the Use of Endovascular Thrombectomy in Proximal Occlusive Stroke Beyond 6 Hours in Patients with Limited Core Infarct

PURPOSE

The safety and efficacy of endovascular thrombectomy (EVT) for patients with proximal occlusive stroke presenting beyond 6 hours and selected on the basis of favorable neuroimaging remains unclear.

MATERIALS AND METHODS

A systematic search was performed from four electronic databases from their inception to Jan 2017. A meta-analysis of outcomes from studies with patients treated beyond 6 hours was compared to those treated within the established 6 hour therapeutic window in randomized trials, selected using conventional imaging methods with CT/CT angiography.

RESULTS

A total of 8 articles met inclusion criteria for the study population (a prospective single-center study, 5 retrospective single-center studies and 2 retrospective multicenter studies). These were compared to the results of three prospective trials of patients treated within 6 hours selected using CT/CT angiography. For patients treated >6 hours and <6 hours respectively, the weighted mean age was 64.7 vs. 67.0 years; the presenting NIHSS was 15.7 vs. 17.1 and the time from symptom onset to puncture was 4.0 hours vs. 15.1 hours. Weighted pooled estimates of successful recanalization (TIMI 2/3 or TICI 2b/3) and favorable outcome (mRS ≤2) were similar between both groups, 70.1% vs. 70.6%, P=0.75 and 38.9% vs. 38.4%, P=0.88 respectively. Pooled mortality measured at 3 months was 22.8% for those treated >6 hours and 12.5% for <6 hours, P<0.0001. Symptomatic intracranial hemorrhage was not significantly different (10.0% vs. 7.7%, P=0.33).

CONCLUSION

When compared to established methods of patient selection, EVT employed beyond 6 hours in those selected with imaging to exclude large core infarcts achieves similar rates of recanalization, and functional outcome but there is a significant increase in mortality despite no increase in symptomatic intracranial hemorrhage.

Cerebral hyperperfusion on arterial spin labeling MRI after reperfusion therapy is related to hemorrhagic transformation

Early detection of hemorrhagic transformation after reperfusion therapy is crucial in acute stroke treatment. Here, we evaluated the relationship between hemorrhagic transformation and post-reperfusion hyperperfusion using pulsed arterial spin labeling (ASL) perfusion MRI and ¹²³I-iodoamphetamine single-photon emission-computed tomography. Patients who developed hemorrhagic transformation showed significantly higher cerebral blood flow in the affected lesion after thrombolysis and/or endovascular intervention. Focal hyperperfusion (ipsilateral to contralateral ratio >1.5) was associated with hemorrhagic transformation after reperfusion (odds ratio, 9.3; 95% confidence interval, 1.4-64.0). Our findings suggest that post-reperfusion hyperperfusion on ASL could represent a reliable marker of hemorrhagic transformation.

Neuron-autonomous transcriptome changes upon ischemia/reperfusion injury

Ischemic stroke and the following reperfusion, an acute therapeutic intervention, can cause irreversible brain damages. However, the underlying pathological mechanisms are still under investigation. To obtain a comprehensive, real-time view of the cell-autonomous mechanisms involved in ischemic stroke and reperfusion, we applied the next-generation sequencing (NGS) technology to characterize the temporal changes in gene expression profiles using primarily cultured hippocampal neurons under an oxygen-glucose deprivation/reperfusion (OGD/R) condition. We first identified the differentially expressed genes (DEGs) between normal cultured neurons, neurons with OGD, and neurons with OGD followed by reperfusion for 6 h, 12 h, and 18 h, respectively. We then performed bioinformatics analyses, including gene ontological (GO) and pathway analysis and co-expression network analysis to screen for novel key pathways and genes involved in the pathology of OGD/R. After we confirmed the changes of selected key genes in hippocampal cultures with OGD/R, we further validated their expression changes in an in vivo ischemic stroke model (MCAO). Finally, we demonstrated that prevention of the up-regulation of a key gene (Itga5) associated with OGD/R promoted hippocampal neuronal survival. Our research thereby provided novel insights into the molecular mechanisms in ischemic stroke pathophysiology and potential targets for therapeutic intervention after ischemic stroke.

Precision Stroke Animal Models: the Permanent MCAO Model Should Be the Primary Model, Not Transient MCAO

An argument for preclinical stroke research to make more use of the permanent middle cerebral artery occlusion (MCAO) model, rather than transient MCAO, is presented. Despite STAIR recommending permanent MCAO as the primary model, preclinical stroke research has not been listened. In 2012, Hossmann reported that 64% of the treatment studies for MCAO used prompt transient MCAO models and only 36% of the studies used permanent MCAO or gradual transient MCAO (i.e., embolic stroke model). Then, in 2014 and 2015, 88% of published basic science studies on large vessel occlusion used the transient MCAO model. However, this model only represents 2.5-11.3% of large vessel stroke patients. Therefore, the transient MCAO model, which mimics stroke with reperfusion, does not accurately reflect the majority of clinical stroke cases. Thus, once again, the argument for studying permanent MCAO as a primary model is made and supported.

Inhibition of miR-143 during ischemia cerebral injury protects neurones through recovery of the hexokinase 2-mediated glucose uptake

Ischemic stroke, a major cause of death, is caused by occlusion of a blood vessel, resulting in significant reduction in regional cerebral blood flow. MiRNAs are a family of short noncoding RNAs (18–22 nts) and bind the 3′-UTR of their target genes to suppress the gene expression post-transcriptionally. In the present study, we report that miR-143 is down-regulated in rat neurones but highly expressed in astrocytes. In vivo middle cerebral artery occlusion (MCAO) and ex vivo oxygen-glucose deprivation (OGD) results showed that miR-143 was significantly induced by ischemia injury. Meanwhile, we observed suppression of glucose uptake and lactate product of rat brain and primary neurones after MCAO or OGD. The glycolysis enzymes hexokinase 2 (HK2), PKM2, and LDHA were inhibited by MCAO or OGD at protein and mRNA levels. In addition, overexpression of miR-143 significantly inhibited HK2 expression, glucose uptake, and lactate product. We report that HK2 is a direct target of miR-143. Importantly, restoration of HK2 in miR-143 overexpressing rat neurones recovered glucose uptake and lactate product. Our results demonstrated inhibition of miR-143 during OGD could protect rat neuronal cells from ischemic brain injury (IBI). In summary, the present study reveals a miRNA-mediated neuron protection during IBI, providing a new strategy for the development of therapeutic agents against IBI.

Biliverdin administration ameliorates cerebral ischemia reperfusion injury in rats and is associated with proinflammatory factor downregulation

Biliverdin (BV), one of the heme oxygenase-1 (HO-1) catalytic products, has been demonstrated to have protective effects in liver ischemia reperfusion injury (IRI). The present study aimed to explore the effects of BV on cerebral IRI, and to investigate the potential mechanisms thereof. Adult male SD rats, weighing 200-240 g, were randomly divided into sham (group S), cerebral ischemia reperfusion control (group C) and BV (group BV) groups. Rats in group C underwent transient middle cerebral artery occlusion (tMCAO) and received 2 ml normal saline; rats in group BV received BV (35 mg/kg) intraperitoneally 15 min prior to reperfusion and 4 h after reperfusion, then twice a day thereafter for 5 days. Group S served as the control. Neurological Severity Scores (NSS) were evaluated at days 1-5 following reperfusion. Staining with 2, 3, 5-triphenyltetrazolium chloride was performed to determine the cerebral infarction at 48 h post reperfusion. mRNA expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, inducible nitric oxide synthase (iNOS) and HO-1 in the ischemic cerebral cortex were detected via reverse transcription-quantitative polymerase chain reaction at 3, 6, 12 and 24 h after reperfusion. Western blotting was used to detect the protein expression levels at 3 h after reperfusion. Compared with group S, the NSS, cerebral infarct volume, and the mRNA and protein expression levels of TNF-α, IL-6, IL-1β, iNOS and HO-1 of Group C were significantly increased (P<0.05). However, BV administration significantly improved and reduced these expression levels (P<0.01). The present study indicates that BV is able to ameliorate cerebral IRI in rats and that the mechanism may be associated with the downregulation of proinflammatory factors.

Neuroprotective Effect of the Ginsenoside Rg1 on Cerebral Ischemic Injury In Vivo and In Vitro Is Mediated by PPARγ-Regulated Antioxidative and Anti-Inflammatory Pathways

The ginsenoside Rg1 exerts a neuroprotective effect during cerebral ischemia/reperfusion injury. Rg1 has been previously reported to improve PPARγ expression and signaling, consequently enhancing its regulatory processes. Due to PPARγ's role in the suppression of oxidative stress and inflammation, Rg1's PPARγ-normalizing capacity may play a role in the observed neuroprotective action of Rg1 during ischemic brain injury. We utilized a middle cerebral artery ischemia/reperfusion injury model in rats in addition to an oxygen glucose deprivation model in cortical neurons to elucidate the mechanisms underlying the neuroprotective effects of Rg1. We found that Rg1 significantly increased PPARγ expression and reduced multiple indicators of oxidative stress and inflammation. Ultimately, Rg1 treatment improved neurological function and diminished brain edema, indicating that Rg1 may exert its neuroprotective action on cerebral ischemia/reperfusion injury through the activation of PPARγ signaling. In addition, the present findings suggested that Rg1 was a potent PPARγ agonist in that it upregulated PPARγ expression and was inhibited by GW9662, a selective PPARγ antagonist. These findings expand our previous understanding of the molecular basis of the therapeutic action of Rg1 in cerebral ischemic injury, laying the ground work for expanded study and clinical optimization of the compound.

Autophagy-regulated AMPAR subunit upregulation in in vitro oxygen glucose deprivation/reoxygenation-induced hippocampal injury

Autophagy has been implicated to mediate experimental cerebral ischemia/reperfusion-induced neuronal death; the underlying molecular mechanisms, though, are poorly understood. In this study, we investigated the role of autophagy in regulating the expression of AMPAR subunits (GluR1, GluR2, and GluR3) in oxygen glucose deprivation/reperfusion (OGD/R)-mediated injury of hippocampal neurons. Our results showed that, OGD/R-induced hippocampal neuron injury was accompanied by accumulation of autophagosomes and autolysosomes in cytoplasm alongside a dramatic increase in expression of autophagy-related genes, LC3 and Beclin 1 and increased intracellular Ca²⁺ levels. Pre-treatment with autophagy inhibitor 3-methyladenine (3-MA) significantly reduced this effect. Moreover, the OGD/R-induced upregulation of mRNA and protein expressions of GluR1, GluR2, and GluR3 were also effectively reversed in cells pretreated with 3-MA. Our findings indicate that OGD/R induced the expression of GluRs by activating autophagy in in vitro cultured hippocampal neurons, which could be effectively reversed by the administration of 3-MA.