Celecoxib induces functional recovery after intracerebral hemorrhage with reduction of brain edema and perihematomal cell death

New targets in spontaneous intracerebral hemorrhage

PURPOSE OF REVIEW

Intracerebral hemorrhage (ICH) is a devastating stroke with limited medical treatments; thus, timely exploration of emerging therapeutic targets is essential. This review focuses on the latest strategies to mitigate secondary brain injury post-ICH other than targeting surgery or hemostasis, addressing a significant gap in clinical practice and highlighting potential improvements in patient outcomes.

RECENT FINDINGS

Promising therapeutic targets to reduce secondary brain injury following ICH have recently been identified, including attenuation of iron toxicity and inhibition of ferroptosis, enhancement of endogenous resorption of hematoma, and modulation of perihematomal inflammatory responses and edema. Additionally, novel insights suggest the lymphatic system of the brain may potentially play a role in hematoma clearance and edema management. Various experimental and early-phase clinical trials have demonstrated these approaches may potentially offer clinical benefits, though most research remains in the preliminary stages.

SUMMARY

Continued research is essential to identify multifaceted treatment strategies for ICH. Clinical translation of these emerging targets could significantly enhance the efficacy of therapeutic interventions and potentially reduce secondary brain damage and improve neurological recovery. Future efforts should focus on large-scale clinical trials to validate these approaches, to pave the way for more effective treatment protocols for spontaneous ICH.

Unique Bioactives from Zombie Fungus (Cordyceps) as Promising Multitargeted Neuroprotective Agents

Cordyceps, also known as "zombie fungus", is a non-poisonous mushroom that parasitizes insects for growth and development by manipulating the host system in a way that makes the victim behave like a "zombie". These species produce promising bioactive metabolites, like adenosine, β-glucans, cordycepin, and ergosterol. Cordyceps has been used in traditional medicine due to its immense health benefits, as it boosts stamina, appetite, immunity, longevity, libido, memory, and sleep. Neuronal loss is the typical feature of neurodegenerative diseases (NDs) (Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS)) and neurotrauma. Both these conditions share common pathophysiological features, like oxidative stress, neuroinflammation, and glutamatergic excitotoxicity. Cordyceps bioactives (adenosine, N6-(2-hydroxyethyl)-adenosine, ergosta-7, 9 (11), 22-trien-3β-ol, active peptides, and polysaccharides) exert potential antioxidant, anti-inflammatory, and anti-apoptotic activities and display beneficial effects in the management and/or treatment of neurodegenerative disorders in vitro and in vivo. Although a considerable list of compounds is available from Cordyceps, only a few have been evaluated for their neuroprotective potential and still lack information for clinical trials. In this review, the neuroprotective mechanisms and safety profile of Cordyceps extracts/bioactives have been discussed, which might be helpful in the identification of novel potential therapeutic entities in the future.

Brain edema formation and therapy after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) accounts for about 10% of all strokes in the United States of America causing a high degree of disability and mortality. There is initial (primary) brain injury due to the mechanical disruption caused by the hematoma. There is then secondary injury, triggered by the initial injury but also the release of various clot-derived factors (e.g., thrombin and hemoglobin). ICH alters brain fluid homeostasis. Apart from the initial hematoma mass, ICH causes blood-brain barrier disruption and parenchymal cell swelling, which result in brain edema and intracranial hypertension affecting patient prognosis. Reducing brain edema is a critical part of post-ICH care. However, there are limited effective treatment methods for reducing perihematomal cerebral edema and intracranial pressure in ICH. This review discusses the mechanisms underlying perihematomal brain edema formation, the effects of sex and age, as well as how edema is resolved. It examines progress in pharmacotherapy, particularly focusing on drugs which have been or are currently being investigated in clinical trials.

Protective effect of isoflurane preconditioning on neurological function in rats with HIE

Hypoxic-ischemic encephalopathy (HIE) is an important cause of neonatal death and disability, which can lead to long-term neurological and motor dysfunction. Currently, inhalation anesthetics are widely used in surgery, and some studies have found that isoflurane (ISO) may have a positive effect on neuroprotection. In this paper, we investigated whether ISO pretreatment has a neuroprotective effect on the neurological function of HIE rats. Here, 7-day-old neonatal rats were randomly divided into a sham group, a hypoxic-ischemic (HI) group, and an ISO pretreatment (pretreatment) group. The pretreatment group was pretreated with 2% ISO for 1 h, followed by the HI group to establish an HI animal model. The HI‑induced neurological injury was evaluated by Zea‑Longa scores and triphenyltetrazolium (TTC) staining. Neuronal number and histomorphological changes were observed with Nissl staining and Hematoxylin-eosin (HE) staining. In addition, motor learning memory function was evaluated by the Morris water maze (MWM), the Y-maze, and the rotarod tests. HI induced severe neurological dysfunction, brain infarction, and cell apoptosis as well as obvious neuron loss in neonatal rats. In the MWM, the rats in the pretreatment group showed a decrease in escape latency (p = 0.042), indicating that pretreatment with ISO could improve the learning ability of HI rats. The results of Nissl staining showed that in the HI group, there was an irregular arrangement of neurons and nuclear fixation; however, the cell damage was significantly reduced and the total number of neurons was increased after ISO pretreatment (p < 0.001). In conclusion, ISO pretreatment improved cognitive function and attenuated HI-induced reduction of Nissl-positive cells and spatial memory impairment, suggesting that pretreatment with ISO before HI modeling could reduce neuronal cell death in the hippocampus after HI.

Potential application of intranasal insulin delivery for treatment of intracerebral hemorrhage: A review of the literature

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke associated with high morbidity and mortality that is considered a medical emergency, mainly managed with adequate blood pressure control and creating a favorable hemostatic condition. However, to date, none of the randomized clinical trials have led to an effective treatment for ICH. It is vital to better understand the mechanisms underlying brain injury to effectively decrease ICH-associated morbidity and mortality. It is well known that initial hematoma formation and its expansion have detrimental consequences. The literature has recently focused on other pathological processes, including oxidative stress, neuroinflammation, blood-brain barrier disruption, edema formation, and neurotoxicity, that constitute secondary brain injury. Since conventional management has failed to improve clinical outcomes significantly, various neuroprotective therapies are tested in preclinical and clinical settings. Unlike intravenous administration, intranasal insulin can reach a higher concentration in the cerebrospinal fluid without causing systemic side effects. Intranasal insulin delivery has been introduced as a novel neuroprotective agent for certain neurological diseases, including ischemic stroke, subarachnoid hemorrhage, and traumatic brain injury. Since there is an overlap of mechanisms causing neuroinflammation in these neurological diseases and ICH, we believe that preclinical studies testing the role of intranasal insulin therapy in ICH are warranted.

Role and Mechanism of Ferroptosis in Neurological Diseases

Background

Ferroptosis, as a new form of cell death, is different from other cell deaths such as autophagy or senescence. Ferroptosis involves in the pathophysiological progress of several diseases, including cancers, cardiovascular diseases, nervous system diseases, and kidney damage. Since oxidative stress and iron deposition are the broad pathological features of neurological diseases, the role of ferroptosis in neurological diseases has been widely explored.

Scope of review

Ferroptosis is mainly characterized by changes in iron homeostasis, iron-dependent lipid peroxidation, and glutamate toxicity accumulation, of which can be specifically reversed by ferroptosis inducers or inhibitors. The ferroptosis is mainly regulated by the metabolism of iron, lipids and amino acids through System Xc⁻, voltage-dependent anion channels, p53, p62-Keap1-Nrf2, mevalonate and other pathways. This review also focus on the regulatory pathways of ferroptosis and its research progress in neurological diseases.

Major conclusions

The current researches of ferroptosis in neurological diseases mostly focus on the key pathways of ferroptosis. At the same time, ferroptosis was found playing a bidirectional regulation role in neurological diseases. Therefore, the specific regulatory mechanisms of ferroptosis in neurological diseases still need to be further explored to provide new perspectives for the application of ferroptosis in the treatment of neurological diseases.

Prenatal Activation of Glucocorticoid Receptors Induces Memory Impairment in a Sex-Dependent Manner: Role of Cyclooxygenase-2

Prenatal exposure to dexamethasone (DEX) results in long-lasting effects on cognitive functions such as learning and memory impairment. However, the mechanisms underlying these DEX-induced deleterious effects are not well known. Here, we assessed whether cyclooxygenase-2 (COX-2) is involved in the impact of prenatal exposure to DEX on learning and memory during adulthood. Pregnant Sprague-Dawley rats received daily injections of either DEX (0.2 mg/kg; i.p.) or saline from gestation day (GD) 14 until GD21. Gene and protein expression of COX-2, as well as presynaptic (synaptophysin) and postsynaptic (postsynaptic density protein-95) proteins, were monitored in the dorsal and ventral hippocampi of adult male and female offspring. A different cohort of adult male and female rat offspring was given daily injections of either vehicle or a specific COX-2 inhibitor (celecoxib 10 mg/kg, i.p.) for 5 consecutive days and was subsequently subjected to Morris water maze memory test. Prenatal DEX enhanced the expression of COX-2 protein and cox-2 mRNA in the dorsal hippocampus of adult female but not male rats. This enhanced COX-2 expression was associated with reduced expression in pre- and postsynaptic proteins and altered memory acquisition and retention. Administration of COX-2-specific inhibitor alleviated prenatal DEX-induced memory impairment in adult female rats. This study suggests that prenatal activation of glucocorticoid receptors stimulates COX-2 gene and protein expression and impairs hippocampal-dependent spatial memory in female but not male rat offspring. Furthermore, COX-2 selective inhibitors can be used to alleviate the long-lasting deleterious effects of corticosteroid medication during pregnancy.

Advances in Immunomodulation and Immune Engineering Approaches to Improve Healing of Extremity Wounds

Delayed healing of traumatic wounds often stems from a dysregulated immune response initiated or exacerbated by existing comorbidities, multiple tissue injury or wound contamination. Over decades, approaches towards alleviating wound inflammation have been centered on interventions capable of a collective dampening of various inflammatory factors and/or cells. However, a progressive understanding of immune physiology has rendered deeper knowledge on the dynamic interplay of secreted factors and effector cells following an acute injury. There is a wide body of literature, both in vitro and in vivo, abstracted on the immunomodulatory approaches to control inflammation. Recently, targeted modulation of the immune response via biotechnological approaches and biomaterials has gained attention as a means to restore the pro-healing phenotype and promote tissue regeneration. In order to fully realize the potential of these approaches in traumatic wounds, a critical and nuanced understanding of the relationships between immune dysregulation and healing outcomes is needed. This review provides an insight on paradigm shift towards interventional approaches to control exacerbated immune response following a traumatic injury from an agonistic to a targeted path. We address such a need by (1) providing a targeted discussion of the wound healing processes to assist in the identification of novel therapeutic targets and (2) highlighting emerging technologies and interventions that utilize an immunoengineering-based approach. In addition, we have underscored the importance of immune engineering as an emerging tool to provide precision medicine as an option to modulate acute immune response following a traumatic injury. Finally, an overview is provided on how an intervention can follow through a successful clinical application and regulatory pathway following laboratory and animal model evaluation.

Predicting mortality from intracranial hemorrhage in patients who undergo allogeneic hematopoietic stem cell transplantation

Intracranial hemorrhage (ICH) is a rare but fatal central nervous system complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, factors that are predictive of early mortality in patients who develop ICH after undergoing allo-HSCT have not been systemically investigated. From January 2008 to June 2020, a total of 70 allo-HSCT patients with an ICH diagnosis formed the derivation cohort. Forty-one allo-HSCT patients with an ICH diagnosis were collected from 12 other medical centers during the same period, and they comprised the external validation cohort. These 2 cohorts were used to develop and validate a grading scale that enables the prediction of 30-day mortality from ICH in all-HSCT patients. Four predictors (lactate dehydrogenase level, albumin level, white blood cell count, and disease status) were retained in the multivariable logistic regression model, and a simplified grading scale (termed the LAWS score) was developed. The LAWS score was adequately calibrated (Hosmer-Lemeshow test, P > .05) in both cohorts. It had good discrimination power in both the derivation cohort (C-statistic, 0.859; 95% confidence interval, 0.776-0.945) and the external validation cohort (C-statistic, 0.795; 95% confidence interval, 0.645-0.945). The LAWS score is the first scoring system capable of predicting 30-day mortality from ICH in allo-HSCT patients. It showed good performance in identifying allo-HSCT patients at increased risk of early mortality after ICH diagnosis. We anticipate that it would help risk stratify allo-HSCT patients with ICH and facilitate future studies on developing individualized and novel interventions for patients within different LAWS risk groups.

Perihematomal Edema After Intracerebral Hemorrhage: An Update on Pathogenesis, Risk Factors, and Therapeutic Advances

Intracerebral hemorrhage (ICH) has one of the worst prognoses among patients with stroke. Surgical measures have been adopted to relieve the mass effect of the hematoma, and developing targeted therapy against secondary brain injury (SBI) after ICH is equally essential. Numerous preclinical and clinical studies have demonstrated that perihematomal edema (PHE) is a quantifiable marker of SBI after ICH and is associated with a poor prognosis. Thus, PHE has been considered a promising therapeutic target for ICH. However, the findings derived from existing studies on PHE are disparate and unclear. Therefore, it is necessary to classify, compare, and summarize the existing studies on PHE. In this review, we describe the growth characteristics and relevant underlying mechanism of PHE, analyze the contributions of different risk factors to PHE, present the potential impact of PHE on patient outcomes, and discuss the currently available therapeutic strategies.

Emerging therapeutic targets for cerebral edema

INTRODUCTION

Cerebral edema is a key contributor to death and disability in several forms of brain injury. Current treatment options are limited, reactive, and associated with significant morbidity. Targeted therapies are emerging based on a growing understanding of the molecular underpinnings of cerebral edema.

AREAS COVERED

We review the pathophysiology and relationships between different cerebral edema subtypes to provide a foundation for emerging therapies. Mechanisms for promising molecular targets are discussed, with an emphasis on those advancing in clinical trials, including ion and water channels (AQP4, SUR1-TRPM4) and other proteins/lipids involved in edema signaling pathways (AVP, COX2, VEGF, and S1P). Research on novel treatment modalities for cerebral edema [including recombinant proteins and gene therapies] is presented and finally, insights on reducing secondary injury and improving clinical outcome are offered.

EXPERT OPINION

Targeted molecular strategies to minimize or prevent cerebral edema are promising. Inhibition of SUR1-TRPM4 (glyburide/glibenclamide) and VEGF (bevacizumab) are currently closest to translation based on advances in clinical trials. However, the latter, tested in glioblastoma multiforme, has not demonstrated survival benefit. Research on recombinant proteins and gene therapies for cerebral edema is in its infancy, but early results are encouraging. These newer modalities may facilitate our understanding of the pathobiology underlying cerebral edema.

Profiling of Blood-Brain Barrier Disruption in Mouse Intracerebral Hemorrhage Models: Collagenase Injection vs. Autologous Arterial Whole Blood Infusion

Disruption of the blood-brain barrier (BBB) and the subsequent formation of brain edema is the most severe consequence of intracerebral hemorrhage (ICH), leading to drastic neuroinflammatory responses and neuronal cell death. A better understanding of ICH pathophysiology to develop effective therapy relies on selecting appropriate animal models. The collagenase injection ICH model and the autologous arterial whole blood infusion ICH model have been developed to investigate the pathophysiology of ICH. However, it remains unclear whether the temporal progression and the underlying mechanism of BBB breakdown are similar between these two ICH models. In this study, we aimed to determine the progression and the mechanism of BBB disruption via the two commonly used murine ICH models: the collagenase-induced ICH model (c-ICH) and the double autologous whole blood ICH model (b-ICH). Intrastriatal injection of 0.05 U collagenase or 20 μL autologous blood was used for a comparable hematoma volume in these two ICH models. Then we analyzed BBB permeability using Evan’s blue and IgG extravasation, evaluated tight junction (TJ) damage by transmission electron microscope (TEM) and Western blotting, and assessed matrix metalloproteinase-9 (MMP-9) activity and aquaporin 4 (AQP4) mRNA expression by Gelatin gel zymography and RT-PCR, respectively. The results showed that the BBB leakage was associated with a decrease in TJ protein expression and an increase in MMP-9 activity and AQP4 expression on day 3 in the c-ICH model compared with that on day 5 in the b-ICH model. Additionally, using TEM, we found that the TJ was markedly damaged on day 3 in the c-ICH model compared with that on day 5 in the b-ICH model. In conclusion, the BBB was disrupted in the two ICH models; compared to the b-ICH model, the c-ICH model presented with a more pronounced disruption of BBB at earlier time points, suggesting that the c-ICH model might be a more suitable model for studying early BBB damage and protection after ICH.

Neuroprotective Therapies for Spontaneous Intracerebral Hemorrhage

Patients who survive the initial ictus of spontaneous intracerebral hemorrhage (ICH) remain vulnerable to subsequent injury of the perilesional parenchyma by molecular and cellular responses to the hematoma. Secondary brain injury after ICH, which contributes to long-term functional impairment and mortality, has emerged as an attractive therapeutic target. This review summarizes preclinical and clinical evidence for neuroprotective therapies targeting secondary injury pathways following ICH. A focus on therapies with pleiotropic antiinflammatory effects that target thrombin-mediated chemotaxis and inflammatory cell migration has led to studies investigating statins, anticholinergics, sphingosine-1-phosphate receptor modulators, peroxisome proliferator activated receptor gamma agonists, and magnesium. Attempts to modulate ICH-induced blood-brain barrier breakdown and perihematomal edema formation has prompted studies of nonsteroidal antiinflammatory agents, matrix metalloproteinase inhibitors, and complement inhibitors. Iron chelators, such as deferoxamine and albumin, have been used to reduce the free radical injury that ensues from erythrocyte lysis. Stem cell transplantation has been assessed for its potential to enhance subacute neurogenesis and functional recovery. Despite promising preclinical results of numerous agents, their outcomes have not yet translated into positive clinical trials in patients with ICH. Further studies are necessary to improve our understanding of the molecular events that promote damage and inflammation of the perihematomal parenchyma after ICH. Elucidating the temporal and pathophysiologic features of this secondary brain injury could enhance the clinical efficacy of neuroprotective therapies for ICH.

Ergosta-7,9(11),22-trien-3β-ol Alleviates Intracerebral Hemorrhage-Induced Brain Injury and BV-2 Microglial Activation

Intracerebral hemorrhage (ICH) is a devastating neurological disorder characterized by an exacerbation of neuroinflammation and neuronal injury, for which few effective therapies are available at present. Inhibition of excessive neuroglial activation has been reported to alleviate ICH-related brain injuries. In the present study, the anti-ICH activity and microglial mechanism of ergosta-7,9(11),22-trien-3β-ol (EK100), a bioactive ingredient from Asian medicinal herb Antrodia camphorate, were evaluated. Post-treatment of EK100 significantly attenuated neurobehavioral deficit and MRI-related brain lesion in the mice model of collagenase-induced ICH. Additionally, EK100 alleviated the inducible expression of cyclooxygenase (COX)-2 and the activity of matrix metalloproteinase (MMP)-9 in the ipsilateral brain regions. Consistently, it was shown that EK100 concentration-dependently inhibited the expression of COX-2 protein in Toll-like receptor (TLR)-4 activator lipopolysaccharide (LPS)-activated microglial BV-2 and primary microglial cells. Furthermore, the production of microglial prostaglandin E₂ and reactive oxygen species were attenuated by EK100. EK100 also attenuated the induction of astrocytic MMP-9 activation. Among several signaling pathways, EK100 significantly and concentration-dependently inhibited activation of c-Jun N-terminal kinase (JNK) MAPK in LPS-activated microglial BV-2 cells. Consistently, ipsilateral JNK activation was markedly inhibited by post-ICH-treated EK100 in vivo. In conclusion, EK100 exerted the inhibitory actions on microglial JNK activation, and attenuated brain COX-2 expression, MMP-9 activation, and brain injuries in the mice ICH model. Thus, EK100 may be proposed and employed as a potential therapeutic agent for ICH.

History of Nonsteroidal Anti-inflammatory Drug Use and Functional Outcomes After Spontaneous Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

Preclinical and clinical studies have suggested a potential benefit from COX-2 inhibition on secondary injury activation after spontaneous intracerebral hemorrhage (ICH). The aim of this study was to investigate the effect of pre-admission NSAID use on functional recovery in spontaneous ICH patients.

METHODS

Consecutive adult ICH patients enrolled in the Intracerebral Hemorrhage Outcomes Project (2009-2018) with available 90-day follow-up data were included. Patients were categorized as NSAID (daily COX inhibitor use ≤ 7 days prior to ICH) and non-NSAID users (no daily COX inhibitor use ≤ 7 days prior to ICH). Primary outcome was the ordinal 90-day modified Rankin Scale (mRS) score. Outcomes were compared between cohorts using multivariable regression and propensity score-matched analyses. A secondary analysis excluding aspirin users was performed.

RESULTS

The NSAID and non-NSAID cohorts comprised 228 and 361 patients, respectively. After 1:1 matching, the matched cohorts each comprised 140 patients. The 90-day mRS were comparable between the NSAID and non-NSAID cohorts in both the unmatched (aOR = 0.914 [0.626-1.336], p = 0.644) and matched (aOR = 0.650 [0.392-1.080], p = 0.097) analyses. The likelihood of recurrent ICH at 90 days was also comparable between the NSAID and non-NSAID cohorts in both the unmatched (aOR = 0.845 [0.359-1.992], p = 0.701) and matched analyses (aOR = 0.732 [0.241-2.220], p = 0.581). In the secondary analysis, the non-aspirin NSAID and non-NSAID cohorts comprised 38 and 361 patients, respectively. After 1:1 matching, the matched cohorts each comprised 38 patients. The 90-day mRS were comparable between the non-aspirin NSAID and non-NSAID cohorts in both the unmatched (aOR = 0.615 [0.343-1.101], p = 0.102) and matched (aOR = 0.525 [0.219-1.254], p = 0.147) analyses. The likelihood of recurrent ICH at 90 days was also comparable between the non-aspirin NSAID and non-NSAID cohorts in both the unmatched (aOR = 2.644 [0.258-27.091], p = 0.413) and matched (aOR = 2.586 [0.228-29.309], p = 0.443) analyses. After the exclusion of patients with DNR or withdrawal of care status, NSAID use was associated with lower mRS at 90 days (aOR = 0.379 [0.212-0.679], p = 0.001), lower mRS at hospital discharge (aOR = 0.505 [0.278-0.919], p = 0.025) and lower 90-day mortality rates (aOR = 0.309 [0.108-0.877], p = 0.027).

CONCLUSIONS

History of nonselective COX inhibition may affect functional outcomes in ICH patients. Pre-admission NSAID use did not appear to worsen the severity of presenting ICH or increase the risk of recurrent ICH. Additional clinical studies may be warranted to investigate the effects of pre-admission NSAID use on ICH outcomes.

Celecoxib-Dependent Neuroprotection in a Rat Model of Transient Middle Cerebral Artery Occlusion (tMCAO) Involves Modifications in Unfolded Protein Response (UPR) and Proteasome

Stroke is one of the main causes of death and disability worldwide. Ischemic stroke results in unfolded/misfolded protein accumulation in endoplasmic reticulum (ER), a condition known as ER stress. We hypothesized that previously reported neuroprotection of celecoxib, a selective inhibitor of cyclooxygenase-2, in transient middle cerebral artery occlusion (tMCAO) model, relies on the ER stress decrease. To probe this hypothesis, Sprague-Dawley rats were subjected to 1 h of tMCAO and treated with celecoxib or vehicle 1 and 24 h after ischemia. Protein and mRNA levels of the main hallmarks of ER stress, unfolded protein response (UPR) activation, UPR-induced cell death, and ubiquitin proteasome system (UPS) and autophagy, the main protein degradation pathways, were measured at 12 and 48 h of reperfusion. Celecoxib treatment decreased polyubiquitinated protein load and ER stress marker expression such as glucose-related protein 78 (GRP78), C/EBP (CCAAT/enhancer-binding protein) homologous protein (CHOP), and caspase 12 after 48 h of reperfusion. Regarding the UPR activation, celecoxib promoted inositol-requiring enzyme 1 (IRE1) pathway instead of double-stranded RNA-activated protein kinase-like ER kinase (PERK) pathway. Furthermore, celecoxib treatment increased proteasome catalytic subunits transcript levels and decreased p62 protein levels, while the microtubule-associated protein 1 light chain 3 (LC3B) II/I ratio remained unchanged. Thus, the ability of celecoxib treatment on reducing the ER stress correlates with the enhancement of IRE1-UPR pathway and UPS degradation. These data support the ability of anti-inflammatory therapy in modulating ER stress and reveal the IRE1 pathway as a promising therapeutic target in stroke therapy.Graphical abstract.

Celecoxib in a Preclinical Model of Repetitive Mild Traumatic Brain Injury: Hippocampal Learning Deficits Persist with Inflammatory and Excitotoxic Neuroprotection

Repetitive mild traumatic brain injuries (mTBIs) contribute to inflammation-induced neurodegeneration. Cycloxygenase (COX) enzymes produce inflammatory cytokines that influence the microglia response to neurotrauma. Celecoxib is a selective COX-2 inhibitor that is prescribed in some conditions of mTBI to alleviate symptoms of concussion, and has shown benefits in neurodegenerative conditions. We investigated molecular pathways of neuroinflammation in response to celecoxib treatment in a mouse model of repetetive mTBI. Fifteen mTBIs were delivered over 23 days in adult male C57BL/6J mice in one of four groups (control, celecoxib without impact, celecoxib with impact, and vehicle with impact). Cognitive function was assessed at 48 h and three months following the final mTBI. Morris Water Maze testing revealed impaired hippocampal spatial learning performance in the celecoxib treatment with the impact group compared to the vehicle with impact control in the acute phase, with celecoxib treatment providing no improvement compared with the control at chronic testing; mRNA analysis of the cerebral cortex and hippocampus revealed expression change, indicating significant improvement in microglial activation, inflammation, excitotoxicity, and neurodegeneration at chronic measurement. These data suggest that, in the acute phase following injury, celecoxib protected against neuroinflammation, but exacerbated clinical cognitive disturbance. Moreover, while there was evidence of neuroprotective alleviation of mTBI pathophysiology at chronic measurement, there remained no change in clinical features.

Ferroptosis: An emerging therapeutic target in stroke

Stroke is a disastrous neurological disease with high morbidity and mortality. The mechanism of the pathological process is extremely complicated and unclear. Although many basic studies have confirmed molecular mechanism of brain injury after stroke, these studies have not yet translated into treatment and clinical application. Ferroptosis is a form of cell death that is distinct from necrosis, apoptosis, and autophagy morphologically and biochemically and is characterized by iron-dependent accumulation of lipid peroxides. Despite ferroptosis being first identified in cancer cells, it was recently revealed to also be a significant factor in the pathological process of stroke. A better understanding of ferroptosis in stroke may provide us with better therapeutic targets to treat this devastating disease. Here, we systematically summarized the current mechanism of ferroptosis and reviewed the current studies regarding the relationship between ferroptosis and stroke.

Knockout of Transient Receptor Potential Melastatin 4 Channel Mitigates Cerebral Edema and Neuronal Injury After Status Epilepticus in Mice

This study aimed to evaluate whether the knockout of transient receptor potential melastatin 4 (TRPM4) could reduce cerebral edema and improve neurologic outcome in a mouse model of status epilepticus (SE). Wild-type (WT) (n = 61) and Trpm4-/- mice (n = 61) with behavioral seizures induced by lithium (10 mEq/kg) and pilocarpine (30-40 mg/kg) were terminated 2.5 hours after the onset of SE. After SE, 28 WT-SE and 27 Trpm4-/--SE mice were observed for 28 days and assessed for survival and cognitive function; the others were killed after 24 hours, 72 hours, or 7 days, and evaluated for cerebral edema and histological injury. In comparison to WT-SE mice, the mortality and cognitive deficit for Trpm4-/--SE mice following SE after 28 days were significantly ameliorated. Trpm4-/--SE mice also showed less water content and cerebral edema assessed by magnetic resonance imaging, and decreased blood-brain barrier breakdown after SE. Moreover, Trpm4 deficiency significantly mitigated neuronal loss, cellular necrosis and apoptosis in the hippocampus and piriform cortex and mitigated astrocytosis and microgliosis. In conclusion, this study suggests that Trmp4 may represent a new target for improving outcomes after SE.

Entinostat improves acute neurological outcomes and attenuates hematoma volume after Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) or hemorrhagic stroke is a major public health problem with no effective treatment. Given the emerging role of epigenetic mechanisms in the pathophysiology of ICH, we tested the hypothesis that a class 1 histone deacetylase inhibitor (HDACi), Entinostat, attenuates neurodegeneration and improves neurobehavioral outcomes after ICH. To address this, we employed a preclinical mouse model of ICH and Entinostat was administered intraperitoneally one-hour post induction of ICH. Entinostat treatment significantly reduced the number of degenerating neurons and TUNEL-positive cells after ICH in comparison to vehicle-treated controls. Moreover, Entinostat treatment significantly reduced hematoma volume, T2-weighted hemorrhagic lesion volume and improved acute neurological outcomes after ICH. Further, Entinostat significantly reduced the hemin-induced release of proinflammatory cytokines in vitro. Consistently, the expression of proinflammatory microglial/macrophage marker, CD16/32, was remarkably reduced in Entinostat treated group after ICH in comparison to control. Altogether, data implicates the potential of class 1 HDACi, Entinostat, in improving acute neurological function after ICH warranting further investigation.

A Multi-Model Pipeline for Translational Intracerebral Haemorrhage Research

Apart from acute and chronic blood pressure lowering, we have no specific medications to prevent intracerebral haemorrhage (ICH) or improve outcomes once bleeding has occurred. One reason for this may be related to particular limitations associated with the current pre-clinical models of ICH, leading to a failure to translate into the clinic. It would seem that a breakdown in the 'drug development pipeline' currently exists for translational ICH research which needs to be urgently addressed. Here, we review the most commonly used pre-clinical models of ICH and discuss their advantages and disadvantages in the context of translational studies. We propose that to increase our chances of successfully identifying new therapeutics for ICH, a bi-directional, 2- or 3-pronged approach using more than one model species/system could be useful for confirming key pre-clinical observations. Furthermore, we highlight that post-mortem/ex-vivo ICH patient material is a precious and underused resource which could play an essential role in the verification of experimental results prior to consideration for further clinical investigation. Embracing multidisciplinary collaboration between pre-clinical and clinical ICH research groups will be essential to ensure the success of this type of approach in the future.

Vof-16 knockout improves the recovery from hypoxic-ischemic brain damage of neonatal rats

Hypoxic-ischemic encephalopathy (HIE) results in high neonatal mortality and severe neurological impairments, and its underlying molecular mechanism underwent extensive investigations. Long non-coding RNA (lncRNA) is considered to be an important regulator on brain development and many neurological diseases. Currently, little is known about the role of Vof-16 (lncRNA) in HIE. We detected the relative expression level of Vof-16 in the cortex and hippocampus of hypoxic-ischemic (HI) models whose successful establishment was verified by TTC staining. Then, Vof-16 knockout rats were generated using the CRISPR/Cas engineering technology to search the specific function of the Vof-16 through a series of behavioral evaluations including Neurological severity scores (NSS), Y-maze test, Morris water maze (MWW) test, open field test, and Rotarod test. The results demonstrated the expression of Vof-16 was substantially up-regulated in the cortex and hippocampus of rats with HI injury. Importantly, Vof-16 knockout facilitated the recovery from long-term HI induced nerve damage and neurobehavioral dysfunctions. In conclusion, this study suggests Vof-16 knockout is a promising treatment target for neonatal HIE.

Brain injury and repair after intracerebral hemorrhage: The role of microglia and brain-infiltrating macrophages

Intracerebral hemorrhage (ICH) is a major public health problem characterized by cerebral bleeding. Despite recent advances in preclinical studies, there is no effective treatment for ICH making it the deadliest subtype of stroke. The lack of effective treatment options partly attributes to the complexity as well as poorly defined pathophysiology of ICH. The emerging evidence indicates the potential of targeting secondary brain damage and hematoma resolution for improving neurological outcomes after ICH. Herein, we provide an overview of our understanding of the functional roles of activated microglia and brain-infiltrating monocyte-derived macrophages in brain injury and repair after ICH. The clinical and preclinical aspects that we discuss in this manuscript are related to ICH that occurs in adults, but not in infants. Also, we attempt to identify the knowledge gap in the field for future functional studies given the potential of targeting microglia and brain-infiltrating macrophages for therapeutic intervention after ICH.

Emerging Pharmacological Treatments for Cerebral Edema: Evidence from Clinical Studies

Cerebral edema, a common and often fatal companion to most forms of acute central nervous system disease, has been recognized since the time of ancient Egypt. Unfortunately, our therapeutic armamentarium remains limited, in part due to historic limitations in our understanding of cerebral edema pathophysiology. Recent advancements have led to a number of clinical trials for novel therapeutics that could fundamentally alter the treatment of cerebral edema. In this review, we discuss these agents, their targets, and the data supporting their use, with a focus on agents that have progressed to clinical trials.

New drugs on the horizon for cerebral edema: what's in the clinical development pipeline?

INTRODUCTION

Research has advanced our understanding of the molecular and cellular mechanisms of cerebral edema and has propelled the development of novel antiedema therapeutics. Current evidence supports aberrant neuro-glial ion transport as a central mechanism that underlies pathological fluid accumulation after central nervous system injury.

AREAS COVERED

Novel agents in clinical development show potential in altering the natural history and treatment of cerebral edema. Using the PubMed and Google Scholar databases, we review recent advances in our understanding of cerebral edema and describe agents under active investigation, their mechanism, and their application in recent and ongoing clinical trials.

EXPERT OPINION

Pharmacotherapies that target molecular mechanisms underlying the compensatory post-injury response of ion channels and transporters that lead to pathological alteration of osmotic gradients are the most promising therapeutic strategies. Repurposing of drugs such as glyburide that inhibit the aberrant upregulation of ion channels such as SUR1-TRPM4, and novel agents, such as ZT-1a, which reestablish physiological regulation of ion channels such as NKCC1/KCC, could be useful adjuvants to prevent and even reverse fluid accumulation in the brain parenchyma.

Neuroprotective Methodologies of Co-Enzyme Q10 Mediated Brain Hemorrhagic Treatment: Clinical and Pre-Clinical Findings

Cerebral brain hemorrhage is associated with the highest mortality and morbidity despite only constituting approximately 10-15% of all strokes classified into intracerebral and intraventricular hemorrhage where most of the patients suffer from impairment in memory, weakness or paralysis in arms or legs, headache, fatigue, gait abnormality and cognitive dysfunctions. Understanding molecular pathology and finding the worsening cause of hemorrhage will lead to explore the therapeutic interventions that could prevent and cure the disease. Mitochondrial ETC-complexes dysfunction has been found to increase neuroinflammatory cytokines, oxidative free radicals, excitotoxicity, neurotransmitter and energy imbalance that are the key neuropathological hallmarks of cerebral hemorrhage. Coenzyme Q10 (CoQ10), as a part of the mitochondrial respiratory chain can effectively restore these neuronal dysfunctions by preventing the opening of mitochondrial membrane transition pore, thereby counteracting cell death events as well as exerts an anti-inflammatory effect by influencing the expression of NF-kB1 dependent genes thus preventing the neuroinflammation and energy restoration. Due to behavior and biochemical heterogeneity in post cerebral brain hemorrhagic pattern different preclinical autologous blood injection models are required to precisely investigate the forthcoming therapeutic strategies. Despite emerging pre-clinical research and resultant large clinical trials for promising symptomatic treatments, there are very less pharmacological interventions demonstrated to improve post operative condition of patients where intensive care is required. Therefore, in current review, we explore the disease pattern, clinical and pre-clinical interventions under investigation and neuroprotective methodologies of CoQ10 precursors to ameliorate post brain hemorrhagic conditions.

Blood-Brain Barrier: More Contributor to Disruption of Central Nervous System Homeostasis Than Victim in Neurological Disorders

The blood-brain barrier (BBB) is a dynamic but solid shield in the cerebral microvascular system. It plays a pivotal role in maintaining central nervous system (CNS) homeostasis by regulating the exchange of materials between the circulation and the brain and protects the neural tissue from neurotoxic components as well as pathogens. Here, we discuss the development of the BBB in physiological conditions and then focus on the role of the BBB in cerebrovascular disease, including acute ischemic stroke and intracerebral hemorrhage, and neurodegenerative disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Finally, we summarize recent advancements in the development of therapies targeting the BBB and outline future directions and outstanding questions in the field. We propose that BBB dysfunction not only results from, but is causal in the pathogenesis of neurological disorders; the BBB is more a contributor to the disruption of CNS homeostasis than a victim in neurological disorders.

Neuroprotective potential of solanesol in a combined model of intracerebral and intraventricular hemorrhage in rats

Intracerebral hemorrhage (ICH) may be caused by trauma, aneurysm and arteriovenous malformation, as can any bleeding within the intracranial vault, including brain parenchyma and adjacent meningeal spaces (aneurism and atreovenous malformation). ICH is the cerebral stroke with the least treatable form. Over time, intraventricular hemorrhage (IVH) is associated with ICH, which contributes to hydrocephalus, and the major cause of most hemorrhagic death (Due to the cerebral hemorrhage and post hemorrhagic surgeries). Most patients suffer from memory impairment, grip strength, posture, and cognitive dysfunctions attributable to cerebral hemorrhage or post-brain hemorrhagic surgery. Nevertheless, a combined model of ICH based IVH is not present pre-clinically. Autologous blood (ALB) injection (20 μl/5 min) in the rat brain triggers hemorrhage, such as factors that further interfere with the normal functioning of neuroinflammatory cytokines, oxidative stress, and neurotransmitter dysfunction, such as CoQ10 insufficiency and dysregulation of mitochondrial ETC-complexes. For the prevention of post-brain hemorrhagic behavioral and neurochemical dysfunctions, there is no specific drug treatment available, only available therapy used to provide symptomatic relief. The current study reveals that long-term administration of Solanesol (SNL) 40 and 60 mg/kg alone and in combination with available drug therapy Donepezil (DNP) 3 mg/kg, Memantine (MEM) 20 mg/kg, Celecoxib (CLB) 20 mg/kg, Pregabalin (PGB) 30 mg/kg, may provide the neuroprotective effect by improving behavioral and neurochemical deficits, and gross pathological changes in ALB induced combined experimental model of ICH-IVH in post brain hemorrhagic conditions in rats. Thus, SNL can be a potential therapeutic approach to improve neuronal mitochondrial dysfunction associated with post brain hemorrhagic behavioral and neurochemical alterations.

MicroRNA-146a protects against intracerebral hemorrhage by inhibiting inflammation and oxidative stress

The present study aimed to investigate the role of microRNA-146a (miR-146a) in intracerebral hemorrhage (ICH), and to further assess its underlying mechanism. An ICH rat model was established in the current study and 1 h following ICH induction, rats were treated with or without an miR-146a mimic. A total of 3 days following ICH induction, rat neurological score, brain water content and neuronal apoptosis were measured via flow cytometry. Levels of pro-inflammatory cytokines tumor necrosis factor-α and interleukin-1β were detected via ELISA and certain biomarkers of oxidative stress, including malondialdehyde, superoxide dismutase and glutathione peroxidase, were also determined in current study. The expression of genes and proteins were detected in current study via reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. MicroRNA.org software and a dual luciferase reporter assay were used to confirm the association between miR-146a and TRAF6. The results of the current study revealed that miR-146a was significantly downregulated in ICH rats, and its overexpression reduced neurological damage and brain edema, as evidenced by decreased neurological scores and brain water content. Results from further analyses demonstrated that the overexpression of miR-146a inhibited neuronal apoptosis, reduced pro-inflammatory cytokine production and prevented oxidative stress in ICH rats. In addition, it was revealed that the upregulation of miR-146a repressed the TRAF6/NF-κB pathway in the brain tissue of ICH rats. TRAF6 was also determined to be a target of miR-146a. In conclusion, these data indicated that miR-146a protects against ICH by inhibiting inflammation and oxidative stress.

Caspase-1 inhibitor exerts brain-protective effects against sepsis-associated encephalopathy and cognitive impairments in a mouse model of sepsis

Sepsis-associated encephalopathy (SAE) manifested clinically in acute and long-term cognitive impairments and associated with increased morbidity and mortality worldwide. The potential pathological changes of SAE are complex and remain to be elucidated. Pyroptosis, a novel programmed cell death, is executed by caspase-1-cleaved GSDMD N-terminal (GSDMD-NT) and we investigated it in peripheral blood immunocytes of septic patients previously. Here, a caspase-1 inhibitor VX765 was treated with CLP-induced septic mice. Novel object recognition test indicated that VX765 treatment reversed cognitive dysfunction in septic mice. Elevated plus maze, tail suspension test and open field test revealed that depressive-like behaviors of septic mice were relieved. Inhibited caspase-1 suppressed the expressions of GSDMD and its cleavage form GSDMD-NT, and reduced pyroptosis in brain at day 1 and day 7 after sepsis. Meantime, inhibited caspase-1 mitigated the expressions of IL-1β, MCP-1 and TNF-α in serum and brain, diminished microglia activation in septic mice, and reduced sepsis-induced brain-blood barrier disruption and ultrastructure damages in brain as well. Inhibited caspase-1 protected the synapse plasticity and preserved long-term potential, which may be the possible mechanism of cognitive functions protective effects of septic mice. In conclusion, caspase-1 inhibition exerts brain-protective effects against SAE and cognitive impairments in a mouse model of sepsis.

Emerging therapeutic targets associated with the immune system in patients with intracerebral haemorrhage (ICH): From mechanisms to translation

Intracranial haemorrhage (ICH) is a life-threatening type of stroke with high mortality, morbidity, and recurrence rates. However, no effective treatment has been established to improve functional outcomes in patients with ICH to date. Strategies targeting secondary brain injury are of great interest in both experimental and translational studies. The immune system is increasingly considered to be a crucial contributor to ICH-induced brain injury because it participates in multiple phases of ICH, from the early vascular rupture events to brain recovery. Various pathobiological processes that contribute to secondary brain injury closely interact with the immune system, such as brain oedema, neuroinflammation, and neuronal damage. Hence, we summarize the immune response to ICH and recent progress in treatments targeting the immune system in this review. The emerging therapeutic strategies that target the immune system after ICH are a particular focus and have been summarized.

Iron toxicity, lipid peroxidation and ferroptosis after intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is a devastating type of stroke with high mortality and morbidity. However, we have few options for ICH therapy and limited knowledge about post-ICH neuronal death and related mechanisms. In the aftermath of ICH, iron overload within the perihaematomal region can induce lethal reactive oxygen species (ROS) production and lipid peroxidation, which contribute to secondary brain injury. Indeed, iron chelation therapy has shown efficacy in preclinical ICH studies. Recently, an iron-dependent form of non-apoptotic cell death known as ferroptosis was identified. It is characterised by an accumulation of iron-induced lipid ROS, which leads to intracellular oxidative stress. The ROS cause damage to nucleic acids, proteins and lipid membranes, and eventually cell death. Recently, we and others discovered that ferroptosis does occur after haemorrhagic stroke in vitro and in vivo and contributes to neuronal death. Inhibition of ferroptosis is beneficial in several in vivo and in vitro ICH conditions. This minireview summarises current research on iron toxicity, lipid peroxidation and ferroptosis in the pathomechanisms of ICH, the underlying molecular mechanisms of ferroptosis and the potential for combined therapeutic strategies. Understanding the role of ferroptosis after ICH will provide a vital foundation for cell death-based ICH treatment and prevention.

Programmed Cell Death after Intracerebral Hemorrhage

Background:

Intracerebral hemorrhage (ICH) accounts for up to 15% of all strokes and is characterized by high rates of mortality and morbidity. The post-ICH brain injury can be distinguished in 1) primary, which are caused by disrup-tion and mechanical deformation of brain tissue due to hematoma growth and 2) secondary, which are induced by microglia activation, mitochondrial dysfunction, neurotransmitter and inflammatory mediator release. Although these events typically lead to necrosis, the occurrence of programmed cell death has also been reported after ICH.

Methods:

We reviewed recent publications describing advance in pre- and clinic ICH research.

Results:

At present, treatment of ICH patients is based on oral anticoagulant reversal, management of blood pressure and other medical complications. Several pre-clinical studies showed promising results and demonstrated that anti-oxidative and anti-inflammatory treatments reduced neuronal cell death, however, to date, all of these attempts have failed in randomized controlled clinical trials. Yet, the time frame of administration may be crucial in translation from animal to clinical studies. Furthermore, the latest pre-clinical research points toward the existence of other, apoptosis-unrelated forms kinds of pro-grammed cell death.

Conclusion:

Our review summarizes current knowledge of pathways leading to programmed cell death after ICH in addition to data from clinical trials. Some of the pre-clinical results have not yet demonstrated clinical confirmation, however they sig-nificantly contribute to our understanding of post-ICH pathology and can contribute to development of new therapeutic ap-proaches, decreasing mortality and improving ICH patients’ quality of life.

Celecoxib Treatment Improves Neurologic Deficit and Reduces Selective Neuronal Loss and Glial Response in Rats after Transient Middle Cerebral Artery Occlusion

Areas of selective neuronal loss (SNL) represent the first morphologic signs of damage in the penumbra region and are considered putative targets for ischemic stroke therapy. We performed a novel assessment of measuring the effects of the anti-inflammatory agent celecoxib by analyzing simultaneously the different neural populations (neurons, astrocytes, and microglia cells) in SNL and non-SNL areas. Rats were subjected to 1 hour of middle cerebral artery occlusion (MCAO) and treated with celecoxib 1 and 24 hours after ischemia. Infarct volume measurements and triple immunostaining of neurons (neuronal nuclear antigen), microglia (ionized calcium-binding adaptor molecule 1), and astroglia were performed after 12 and 48 hours of reperfusion. Motor response was tested by standard behavioral assays at 3, 12, 24, and 48 hours. Confocal analysis revealed that the percentage of SNL areas, microglia densities, and glial activation increased at 48 hours of reperfusion. Celecoxib treatment improved the neurologic deficit, reduced the infarct volume by 50% after 48 hours of reperfusion, and resulted in a reduced percentage of SNL areas and microglia and astroglia reactivity after 48 hours of reperfusion. This study proves, for the first time, that celecoxib presents postischemic neuroprotective effects in a transient MCAO model, prevents or delays the presence of SNL areas, and reduces glial activation.

Salubrinal and robenacoxib treatment after global cerebral ischemia. Exploring the interactions between ER stress and inflammation

BACKGROUND

Blood reperfusion of the ischemic tissue after stroke promotes increases in the inflammatory response as well as accumulation of unfolded/misfolded proteins in the cell, leading to endoplasmic reticulum (ER) stress. Both Inflammation and ER stress are critical processes in the delayed death of the cells damaged after ischemia. The aim of this study is to check the putative synergic neuroprotective effect by combining anti-inflammatory and anti-ER stress agents after ischemia.

METHODS

The study was performed on a two-vessel occlusion global cerebral ischemia model. Animals were treated with salubrinal one hour after ischemia and with robenacoxib at 8 h and 32 h after ischemia. Parameters related to the integrity of the blood-brain barrier (BBB), such as matrix metalloproteinase 9 and different cell adhesion molecules (CAMs), were analyzed by qPCR at 24 h and 48 h after ischemia. Microglia and cell components of the neurovascular unit, including neurons, endothelial cells and astrocytes, were analyzed by immunofluorescence after 48 h and seven days of reperfusion.

RESULTS

Pharmacologic control of ER stress by salubrinal treatment after ischemia, revealed a neuroprotective effect over neurons that reduces the transcription of molecules involved in the impairment of the BBB. Robenacoxib treatment stepped neuronal demise forward, revealing a detrimental effect of this anti-inflammatory agent. Combined treatment with robenacoxib and salubrinal after ischemia prevented neuronal loss and changes in components of the neurovascular unit and microglia observed when animals were treated only with robenacoxib.

CONCLUSION

Combined treatment with anti-ER stress and anti-inflammatory agents is able to provide enhanced neuroprotective effects reducing glial activation, which opens new avenues in therapies against stroke.

SIRT1/PGC-1α Signaling Promotes Mitochondrial Functional Recovery and Reduces Apoptosis after Intracerebral Hemorrhage in Rats

Silent information regulator 1 (SIRT1) exerts neuroprotection in many neurodegenerative diseases. However, it is not clear if SIRT1 has protective effects after intracerebral hemorrhage (ICH)-induced brain injury in rats. Thus, our goal was to examine the influence of SIRT1 on ICH injuries and any underlying mechanisms of this influence. Brain injury was induced by autologous arterial blood (60 μL) injection into rat brains, and data show that activation of SIRT1 with SRT1720 (5 mg/kg) restored nuclear SIRT1, deacetylation of PGC-1α, and mitochondrial biogenesis and decreased mortality, behavioral deficits, and brain water content without significant changes in phosphorylated AMP-activated protein kinase (pAMPK) induced by ICH. Activation of SIRT1 with SRT1720 also restored mitochondrial electron transport chain proteins and decreased apoptotic proteins in ICH; however, these changes were reversed after ICH. In contrast, treatment with PGC-1α siRNA yielded opposite effects. To explore the protective effects of SIRT1 after ICH, siRNAs were used to knockdown SIRT1. Treatment with SIRT1 siRNA increased mortality, behavioral deficits, brain water content, mitochondrial dysfunction, and neurocyte apoptosis after ICH. Thus, activation of SIRT1 promotes recovery of mitochondrial protein and function by increasing mitochondrial biogenesis and reduces apoptosis after ICH via the PGC-1α mitochondrial pathway. These data may suggest a new therapeutic approach for ICH injuries.

The Role of Inflammatory Response in Stroke Associated Programmed Cell Death

Stroke represents devastating pathology which is associated with a high morbidity and mortality. Initial damage caused directly by the onset of stroke, primary injury, may be eclipsed by secondary injury which may have a much more devastating effect on the brain. Primary injury is predominantly associated with necrotic cell death due to fatal insufficiency of oxygen and glucose. Secondary injury may on the contrary, lead apoptotic cell death due to structural damage which is not compatible with cellular functions or which may even represent the danger of malign transformation. The immune system is responsible for surveillance, defense and healing processes and the immune system plays a major role in triggering programmed cell death. Severe pathologies, such as stroke, are often associated with deregulation of the immune system, resulting in aggravation of secondary brain injury. The goal of this article is to overview the current knowledge about the role of immune system in the pathophysiology of stroke with respect to programmed neuronal cell death as well as to discuss current therapeutic strategies targeting inflammation after stroke.

Role of flunarizine hydrochloride in secondary brain injury following intracerebral hemorrhage in rats

This study aimed to explore the role and mechanism(s) of flunarizine hydrochloride in the intracerebral hemorrhage (ICH) rats. The 32 adult male Sprague Dawley (SD) rats were randomly assigned into four groups: control group, sham group, ICH group, and FLU + ICH group. The effects of flunarizine hydrochloride were assessed on the basis of hematoma volume, blood–brain barrier (BBB) integrity, and brain water content in the ICH rat models. The role of flunarizine hydrochloride in cell recovery was assessed by behavioral scores, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot assay. Involvement of PI3K/AKT pathway in exerting the effect of flunarizine hydrochloride was also determined. Results showed that the hematoma volume, BBB integrity, and brain water content were significantly decreased in the FLU + ICH group. Cell apoptosis significantly increased in the ICH model group, while flunarizine hydrochloride decreased this increase. The expressions of glial cell line-derived neurotrophic factor (GDNF), neuroglobin (NGB), and p-AKT were increased after flunarizine hydrochloride treatment in ICH rats. In conclusion, flunarizine hydrochloride has protective effects against ICH by reducing brain injury, cell apoptosis, and the activation of P13K/AKT pathway. These findings provide a theoretical basis for the treatment of flunarizine hydrochloride in ICH.

MicroRNA-27b inhibition promotes Nrf2/ARE pathway activation and alleviates intracerebral hemorrhage-induced brain injury

Oxidative stress and neuroinflammation are the key factors leading to secondary brain injury after intracerebral hemorrhage (ICH). We investigated the effects of miR-27b, an oxidative stress-responsive microRNA, on ICH-induced brain injury in rats. The ICH model was induced by intracerebral injection of collagenase. Following ICH, miR-27b expression in the striatum was reduced, whereas expression of Nrf2 mRNA and protein was increased. In PC12 cells, overexpression of miR-27b reduced expression of Nrf2, Hmox1, Sod1 and Nqo1, while miR-27b inhibition had the opposite effects. Dual luciferase reporter assays showed that Nrf2 mRNA was a direct target of miR-27b. Intracerebroventricular injection of miR-27b antagomir and transfection of miR-27b inhibitor inhibited endogenous miR-27b in rats and PC12 cells, respectively. MiR-27b antagomir promoted activation of the ICH-induced Nrf2/ARE pathway and reduced the lipid peroxidation, neuroinflammation, cell death and neurological deficits otherwise seen after ICH. In PC12 cells, the miR-27b inhibitor diminished iron-induced oxidative stress, inflammation and apoptosis, and those effects were blocked by Nrf2 knockdown. These results demonstrate that miR-27b inhibition alleviates ICH-induced brain injury, which may be explained in part by its regulation on the Nrf2/ARE pathway.

Neuroprotective strategies following intraparenchymal hemorrhage

Intracerebral hemorrhage and, more specifically, intraparenchymal hemorrhage, are devastating disease processes with poor clinical outcomes. Primary injury to the brain results from initial hematoma expansion while secondary hemorrhagic injury occurs from blood-derived products such as hemoglobin, heme, iron, and coagulation factors that overwhelm the brains natural defenses. Novel neuroprotective treatments have emerged that target primary and secondary mechanisms of injury. Nonetheless, translational application of neuroprotectants from preclinical to clinical studies has yet to show beneficial clinical outcomes. This review summarizes therapeutic agents and neuroprotectants in ongoing clinical trials aimed at targeting primary and secondary mechanisms of injury after intraparenchymal hemorrhage.

Preclinical Studies and Translational Applications of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) which refers to bleeding in the brain is a very deleterious condition with high mortality and disability rate. Surgery or conservative therapy remains the treatment option. Various studies have divided the disease process of ICH into primary and secondary injury, for which knowledge into these processes has yielded many preclinical and clinical treatment options. The aim of this review is to highlight some of the new experimental drugs as well as other treatment options like stem cell therapy, rehabilitation, and nanomedicine and mention some translational clinical applications that have been done with these treatment options.

Glibenclamide ameliorates cerebral edema and improves outcomes in a rat model of status epilepticus

Glibenclamide (GBC), a sulfonylurea receptor 1 blocker, emerges recently as a promising neuron protectant in various neurological disorders. This study aimed to determine whether GBC improves survival and neurological outcome of status epilepticus (SE). Male Sprague-Dawley rats successfully undergoing SE for 2.5 h (n = 134) were randomly assigned to GBC or vehicle group. Rats in the GBC group received a loading dose of 10 μg/kg of GBC, followed by 1.2 μg/6 h for 3 days, while same dose of vehicle was used as control. The 28-day survival rate in the GBC group (11/23) was significantly higher than that in the vehicle group (8/36). In addition, the frequency and duration of spontaneous recurrent seizures in SE rats were profoundly reduced by GBC but not by vehicle treatment. Moreover, cognitive impairment was observed in the SE rats at day 28, which was reversed by GBC treatment. Meanwhile, cerebral edema, as well as neuronal loss, was decreased in several brain areas in the GBC group. Additionally, on the molecular basis, the subunits of sulfonylurea receptor 1/transient receptor potential M4 (SUR1-TRPM4) heterodimer were both strongly upregulated after SE but partly suppressed by GBC treatment. Furthermore, gene knockdown of Trpm4 in SE rats reduced BBB disruption and neuronal loss, similar to the inhibitory effects with GBC treatment. Taken together, GBC treatment markedly improved survival and neurologic outcomes after SE. The salutary effects of GBC were correlated to the alleviation of cerebral edema and reduction in neurological injury via down-regulation of SUR1-TRPM4 channel.

Anti-high mobility group box-1 (HMGB1) antibody inhibits hemorrhage-induced brain injury and improved neurological deficits in rats

As one of the most lethal stroke subtypes, intracerebral hemorrhage (ICH) is acknowledged as a serious clinical problem lacking effective treatment. Available evidence from preclinical and clinical studies suggests that inflammatory mechanisms are involved in the progression of ICH-induced secondary brain injury. High mobility group box-1 (HMGB1) is a ubiquitous and abundant nonhistone DNA-binding protein, and is also an important proinflammatory molecule once released into the extracellular space from the nuclei. Here, we show that treatment with neutralizing anti-HMGB1 mAb (1 mg/kg, i.v. twice) remarkably ameliorated ICH-injury induced by local injection of collagenase IV in the striatum of rats. Administration of anti-HMGB1 mAb inhibited the release of HMGB1 into the extracellular space in the peri-hematomal region, reduced serum HMGB1 levels and decreased brain edema by protecting blood-brain barrier integrity, in association with decreased activated microglia and the expression of inflammation-related factors at 24 h after ICH. Consequently, anti-HMGB1 mAb reduced the oxidative stress and improved the behavioral performance of rats. These results strongly indicate that HMGB1 plays a critical role in the development of ICH-induced secondary injury through the amplification of plural inflammatory responses. Intravenous injection of neutralizing anti-HMGB1 mAb has potential as a novel therapeutic strategy for ICH.

Inhibition of neuronal ferroptosis protects hemorrhagic brain

Intracerebral hemorrhage (ICH) causes high mortality and morbidity, but our knowledge of post-ICH neuronal death and related mechanisms is limited. In this study, we first demonstrated that ferroptosis, a newly identified form of cell death, occurs in the collagenase-induced ICH model in mice. We found that administration of ferrostatin-1, a specific inhibitor of ferroptosis, prevented neuronal death and reduced iron deposition induced by hemoglobin in organotypic hippocampal slice cultures (OHSCs). Mice treated with ferrostatin-1 after ICH exhibited marked brain protection and improved neurologic function. Additionally, we found that ferrostatin-1 reduced lipid reactive oxygen species production and attenuated the increased expression level of PTGS2 and its gene product cyclooxygenase-2 ex vivo and in vivo. Moreover, ferrostatin-1 in combination with other inhibitors that target different forms of cell death prevented hemoglobin-induced cell death in OHSCs and human induced pluripotent stem cell-derived neurons better than any inhibitor alone. These results indicate that ferroptosis contributes to neuronal death after ICH, that administration of ferrostatin-1 protects hemorrhagic brain, and that cyclooxygenase-2 could be a biomarker of ferroptosis. The insights gained from this study will advance our knowledge of the post-ICH cell death cascade and be essential for future preclinical studies.

Baicalein Promotes Neuronal and Behavioral Recovery After Intracerebral Hemorrhage Via Suppressing Apoptosis, Oxidative Stress and Neuroinflammation

Intracerebral hemorrhage (ICH) is an important public health problem in neurology, which is not only associated with high mortality but also leading to disability. Yet no satisfactory treatment has been developed. The secondary injury that resulted from a number of self-destructive processes such as neuroinflammation, apoptosis and oxidative stress, is the key factor contributing to ICH-induced brain damage. Baicalein has been proved to improve neuronal functional recovery in rat model of subarachnoid hemorrhage and ischemic brain damage. To investigate the effect of baicalein on ICH and its underlying mechanism, a collagenase-induced ICH rat model was performed. Baicalein treatment significantly decreased neurological severity score at day 1 and 3 after ICH injury. Our results showed that the lesion volume, the brain water content, the expression levels of four pro-inflammatory cytokines (IL-1β, IL-4 and IL-6 and TNF-α) and the numbers of apoptotic cells were reduced significantly in ICH rats receiving baicalein treatment, especially in 50 mg/kg baicalein-treated group. Moreover, baicalein increased SOD and GSH-Px activities and down-regulated MDA level of brain tissues in rats. These results suggested that the therapeutic efficacy of baicalein on repairing brain damage is probably caused by suppressing apoptosis, oxidative stress and neuroinflammation. Baicalein could be developed into a novel drug for clinical treatment of ICH and ICH-related brain injuries.

Cerebroprotection by the neuronal PGE2 receptor EP2 after intracerebral hemorrhage in middle-aged mice

Inflammatory responses mediated by prostaglandins such as PGE₂ may contribute to secondary brain injury after intracerebral hemorrhage (ICH). However, the cell-specific signaling by PGE₂ receptor EP2 differs depending on whether the neuropathic insult is acute or chronic. Using genetic and pharmacologic approaches, we investigated the role of EP2 receptor in two mouse models of ICH induced by intrastriatal injection of collagenase or autologous arterial whole blood. We used middle-aged male mice to enhance the clinical relevance of the study. EP2 receptor was expressed in neurons but not in astrocytes or microglia after collagenase-induced ICH. Brain injury after collagenase-induced ICH was associated with enhanced cellular and molecular inflammatory responses, oxidative stress, and matrix metalloproteinase (MMP)-2/9 activity. EP2 receptor deletion exacerbated brain injury, brain swelling/edema, neuronal death, and neurobehavioral deficits, whereas EP2 receptor activation by the highly selective agonist AE1-259-01 reversed these outcomes. EP2 receptor deletion also exacerbated brain edema and neurologic deficits in the blood ICH model. These findings support the premise that neuronal EP2 receptor activation by PGE₂ protects brain against ICH injury in middle-aged mice through its anti-inflammatory and anti-oxidant effects and anti-MMP-2/9 activity. PGE₂/EP2 signaling warrants further investigation for potential use in ICH treatment.

Stroke Lesions in a Large Upper Limb Rehabilitation Trial Cohort Rarely Match Lesions in Common Preclinical Models

BACKGROUND

Stroke patients with mild-moderate upper extremity motor impairments and minimal sensory and cognitive deficits provide a useful model to study recovery and improve rehabilitation. Laboratory-based investigators use lesioning techniques for similar goals.

OBJECTIVE

To determine whether stroke lesions in an upper extremity rehabilitation trial cohort match lesions from the preclinical stroke recovery models used to drive translational research.

METHODS

Clinical neuroimages from 297 participants enrolled in the Interdisciplinary Comprehensive Arm Rehabilitation Evaluation (ICARE) study were reviewed. Images were characterized based on lesion type (ischemic or hemorrhagic), volume, vascular territory, depth (cortical gray matter, cortical white matter, subcortical), old strokes, and leukoaraiosis. Lesions were compared with those of preclinical stroke models commonly used to study upper limb recovery.

RESULTS

Among the ischemic stroke participants, median infarct volume was 1.8 mL, with most lesions confined to subcortical structures (61%) including the anterior choroidal artery territory (30%) and the pons (23%). Of ICARE participants, <1% had lesions resembling proximal middle cerebral artery or surface vessel occlusion models. Preclinical models of subcortical white matter injury best resembled the ICARE population (33%). Intracranial hemorrhage participants had small (median 12.5 mL) lesions that best matched the capsular hematoma preclinical model.

CONCLUSIONS

ICARE subjects are not representative of all stroke patients, but they represent a clinically and scientifically important subgroup. Compared with lesions in general stroke populations and widely studied animal models of recovery, ICARE participants had smaller, more subcortically based strokes. Improved preclinical-clinical translational efforts may require better alignment of lesions between preclinical and human stroke recovery models.