The science of stroke: mechanisms in search of treatments

Transcription Factor Forkhead Box P (Foxp) 1 Reduces Brain Damage During Cerebral Ischemia-Reperfusion Injury in Mice Through FUN14 Domain-containing Protein 1

Mitophagy plays a significant role in modulating the activation of pyrin domain-containing protein 3 (NLRP3) inflammasome, which is a major contributor to the inflammatory response that exacerbates cerebral ischemia-reperfusion (I/R) injury. Despite this, the transcriptional regulation mechanism that governs mitophagy remains unclear. This study sought to explore the potential mechanism of Forkhead Box P1 (Foxp1) and its impact on cerebral I/R injury. We investigated the potential neuroprotective role of Foxp1 in cerebral I/R injury by the middle cerebral artery occlusion (MCAO) mouse model. Additionally, we assessed whether FUN14 domain-containing protein 1 (FUNDC1) could rescue the protective effect of Foxp1. Our results showed that overexpression of Foxp1 prevented brain damage during cerebral I/R injury and promoted NLRP3 inflammasome activation, whereas knockdown of Foxp1 had the opposite effect. Notably, Foxp1 overexpression directly promotes FUNDC1 expression, enhanced mitophagy activation, and inhibited the inflammatory response mediated by the NLRP3 inflammasome. Furthermore, we confirmed through chromatin immunoprecipitation (ChIP) and luciferase reporter assays that FUNDC1 is a direct target gene of Foxp1 downstream. Furthermore, the knockdown of FUNDC1 reversed the increased activation of mitophagy and suppressed NLRP3 inflammasome activation induced by Foxp1 overexpression. Collectively, our findings suggest that Foxp1 inhibits NLRP3 inflammasome activation through FUNDC1 to reduce cerebral I/R injury.

Targeting Neurogenesis in Seeking Novel Treatments for Ischemic Stroke

The interruption of cerebral blood flow leads to ischemic cell death and results in ischemic stroke. Although ischemic stroke is one of the most important causes of long-term disability and mortality, limited treatments are available for functional recovery. Therefore, extensive research has been conducted to identify novel treatments. Neurogenesis is regarded as a fundamental mechanism of neural plasticity. Therefore, therapeutic strategies targeting neurogenesis are thought to be promising. Basic research has found that therapeutic intervention including cell therapy, rehabilitation, and pharmacotherapy increased neurogenesis and was accompanied by functional recovery after ischemic stroke. In this review, we consolidated the current knowledge of the relationship between neurogenesis and treatment for ischemic stroke. It revealed that many treatments for ischemic stroke, including clinical and preclinical ones, have enhanced brain repair and functional recovery post-stroke along with neurogenesis. However, the intricate mechanisms of neurogenesis and its impact on stroke recovery remain areas of extensive research, with numerous factors and pathways involved. Understanding neurogenesis will lead to more effective stroke treatments, benefiting not only stroke patients but also those with other neurological disorders. Further research is essential to bridge the gap between preclinical discoveries and clinical implementation.

Ca2+-dependent rapid uncoupling of astrocytes upon brief metabolic stress

Astrocytic gap junctional coupling is a major element in neuron-glia interaction. There is strong evidence that impaired coupling is involved in neurological disorders. Reduced coupling was, e.g., demonstrated for core regions of ischemic stroke that suffer from massive cell death. In the surrounding penumbra, cells may recover, but recovery is hampered by spreading depolarizations, which impose additional metabolic stress onto the tissue. Spreading depolarizations are characterized by transient breakdown of cellular ion homeostasis, including pH and Ca2+, which might directly affect gap junctional coupling. Here, we exposed acute mouse neocortical tissue slices to brief metabolic stress and examined its effects on the coupling strength between astrocytes. Changes in gap junctional coupling were assessed by recordings of the syncytial isopotentiality. Moreover, quantitative ion imaging was performed in astrocytes to analyze the mechanisms triggering the observed changes. Our experiments show that a 2-minute perfusion of tissue slices with blockers of glycolysis and oxidative phosphorylation causes a rapid uncoupling in half of the recorded cells. They further indicate that uncoupling is not mediated by the accompanying (moderate) intracellular acidification. Dampening large astrocytic Ca2+ loads by removal of extracellular Ca2+ or blocking Ca2+ influx pathways as well as a pharmacological inhibition of calmodulin, however, prevent the uncoupling. Taken together, we conclude that astrocytes exposed to brief episodes of metabolic stress can undergo a rapid, Ca2+/calmodulin-dependent uncoupling. Such uncoupling may help to confine and reduce cellular damage in the ischemic penumbra in vivo.

PLA2G2E-mediated lipid metabolism triggers brain-autonomous neural repair after ischemic stroke

The brain is generally resistant to regeneration after damage. The cerebral endogenous mechanisms triggering brain self-recovery have remained unclarified to date. We here discovered that the secreted phospholipase PLA2G2E from peri-infarct neurons generated dihomo-γ-linolenic acid (DGLA) as necessary for triggering brain-autonomous neural repair after ischemic brain injury. Pla2g2e deficiency diminished the expression of peptidyl arginine deiminase 4 (Padi4), a global transcriptional regulator in peri-infarct neurons. Single-cell RNA sequencing (scRNA-seq) and epigenetic analysis demonstrated that neuronal PADI4 had the potential for the transcriptional activation of genes associated with recovery processes after ischemic stroke through histone citrullination. Among various DGLA metabolites, we identified 15-hydroxy-eicosatrienoic acid (15-HETrE) as the cerebral metabolite that induced PADI4 in peri-infarct-surviving neurons. Administration of 15-HETrE enhanced functional recovery after ischemic stroke. Thus, our research clarifies the promising potential of brain-autonomous neural repair triggered by the specialized lipids that initiate self-recovery processes after brain injury.

Time-dependent dual effect of microglia in ischemic stroke

Stroke, the third leading cause of death and disability worldwide, is classified into ischemic or hemorrhagic, in which approximately 85% of strokes are ischemic. Ischemic stroke occurs as a result of arterial occlusion due to embolus or thrombus, with ischemia in the perfusion territory supplied by the occluded artery. The traditional concept that ischemic stroke is solely a vascular occlusion disorder has been expanded to include the dynamic interaction between microglia, astrocytes, neurons, vascular cells, and matrix components forming the "neurovascular unit." Acute ischemic stroke triggers a wide spectrum of neurovascular disturbances, glial activation, and secondary neuroinflammation that promotes further injury, ultimately resulting in neuronal death. Microglia, as the resident macrophages in the central nervous system, is one of the first responders to ischemic injury and plays a significant role in post-ischemic neuroinflammation. In this review, we reviewed the mechanisms of microglia in multiple stages of post-ischemic neuroinflammation development, including acute, sub-acute and chronic phases of stroke. A comprehensive understanding of the dynamic variation and the time-dependent role of microglia in post-stroke neuroinflammation could aid in the search for more effective therapeutics and diagnostic strategies for ischemic stroke.

1,8-Cineole Alleviates OGD/R-Induced Oxidative Damage and Restores Mitochondrial Function by Promoting the Nrf2 Pathway

This study examined the effects of 1,8-cineole on reducing oxidative stress injury and restoring mitochondrial function in oxygen-glucose deprivation and reoxygenation (OGD/R) HT22 cells via the nuclear factor erythrocyte 2 related factor 2 (Nrf2) pathway. The optimal concentration of 1,8-cineole to reduce OGD/R injury was screened via cell morphology, cell survival rate, and lactate dehydrogenase (LDH) leakage rate. Oxidative damage was observed by measuring superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (CAT) activities, and reactive oxygen species (ROS), glutathione (GSH), protein carbonyl, malondialdehyde (MDA), lipid peroxidation (LPO) content, and 8-hydroxy-2 deoxyguanosine (8-OHDG) expression. Mitochondrial function was observed by mitochondrial membrane potential (MMP) and ATPase activity. Nrf2 pathways were observed by the expression levels of total Nrf2, nucleus Nrf2, reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H): quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1), the mRNA levels of HO-1 and NQO1. Among different concentrations of 1,8-cineole for promoting HT22 cell proliferation and attenuated OGD/R injury, 10 µmol/L 1,8-cineole was the best. After 1,8-cineole treatment, SOD, GSH-PX, and CAT activities and GSH content increased, while ROS, MDA, LPO, protein carbonyl, and 8-OHDG levels decreased. 1,8-Cineole could restore MMP and increase mitochondrial enzyme activity. It could also increase the total Nrf2, nucleus Nrf2, NQO1, and HO-1, and Nrf2 inhibitor brusatol reduced the effect of 1,8-cineole. Immunofluorescence assay showed that 1,8-cineole could facilitate the transfer of Nrf2 into the nucleus. 1,8-cineole increased the mRNA levels of NQO1 and HO-1. The above results showed that 1,8-cineole could alleviate OGD/R-induced oxidative damage and restores mitochondrial function by activating the Nrf2 signal pathway.

Smart Liposomal Nanocarrier Enhanced the Treatment of Ischemic Stroke through Neutrophil Extracellular Traps and Cyclic Guanosine Monophosphate-Adenosine Monophosphate Synthase-Stimulator of Interferon Genes (cGAS-STING) Pathway Inhibition of Ischemic Penumbra

Brain inflammation is regarded as one of the leading causes that aggravates secondary brain injury and hinders the prognosis of ischemic stroke. After ischemic stroke, high quantities of peripheral neutrophils are recruited to brain lesions and release neutrophil extracellular traps (NETs), leading to the aggravation of blood-brain barrier (BBB) damage, activation of microglia, and ultimate neuronal death. Herein, a smart multifunctional delivery system has been developed to regulate immune disorders in the ischemic brain. Briefly, Cl-amidine, an inhibitor of peptidylarginine deiminase 4 (PAD4), is encapsulated into self-assembled liposomal nanocarriers (C-Lipo/CA) that are modified by reactive oxygen species (ROS)-responsive polymers and fibrin-binding peptide to achieve targeting ischemic lesions and stimuli-responsive release of a drug. In the mouse model of cerebral artery occlusion/reperfusion (MCAO), C-Lipo/CA can suppress the NETs release process (NETosis) and further inhibit the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway in an ischemic brain. In addition, MCAO mice treated with C-Lipo/CA significantly mitigated ischemic and reperfusion injury, with a reduction in the area of cerebral infarction to 12.1%, compared with the saline group of about 46.7%. These results demonstrated that C-Lipo/CA, which integrated microglia regulation, BBB protection, and neuron survival, exerts a potential therapy strategy to maximize ameliorating the mortality of ischemic stroke.

Integrative Approaches in Acute Ischemic Stroke: From Symptom Recognition to Future Innovations

Among the high prevalence of cerebrovascular diseases nowadays, acute ischemic stroke stands out, representing a significant worldwide health issue with important socio-economic implications. Prompt diagnosis and intervention are important milestones for the management of this multifaceted pathology, making understanding the various stroke-onset symptoms crucial. A key role in acute ischemic stroke management is emphasizing the essential role of a multi-disciplinary team, therefore, increasing the efficiency of recognition and treatment. Neuroimaging and neuroradiology have evolved dramatically over the years, with multiple approaches that provide a higher understanding of the morphological aspects as well as timely recognition of cerebral artery occlusions for effective therapy planning. Regarding the treatment matter, the pharmacological approach, particularly fibrinolytic therapy, has its merits and challenges. Endovascular thrombectomy, a game-changer in stroke management, has witnessed significant advances, with technologies like stent retrievers and aspiration catheters playing pivotal roles. For select patients, combining pharmacological and endovascular strategies offers evidence-backed benefits. The aim of our comprehensive study on acute ischemic stroke is to efficiently compare the current therapies, recognize novel possibilities from the literature, and describe the state of the art in the interdisciplinary approach to acute ischemic stroke. As we aspire for holistic patient management, the emphasis is not just on medical intervention but also on physical therapy, mental health, and community engagement. The future holds promising innovations, with artificial intelligence poised to reshape stroke diagnostics and treatments. Bridging the gap between groundbreaking research and clinical practice remains a challenge, urging continuous collaboration and research.

Integrated inflammatory signaling landscape response after delivering Elovanoid free-fatty-acid precursors leading to experimental stroke neuroprotection

Despite efforts to identify modulatory neuroprotective mechanisms of damaging ischemic stroke cascade signaling, a void remains on an effective potential therapeutic. The present study defines neuroprotection by very long-chain polyunsaturated fatty acid (VLC-PUFA) Elovanoid (ELV) precursors C-32:6 and C-34:6 delivered intranasally following experimental ischemic stroke. We demonstrate that these precursors improved neurological deficit, decreased T2WI lesion volume, and increased SMI-71 positive blood vessels and NeuN positive neurons, indicating blood-brain barrier (BBB) protection and neurogenesis modulated by the free fatty acids (FFAs) C-32:6 and C-34:6. Gene expression revealed increased anti-inflammatory and pro-homeostatic genes and decreases in expression of pro-inflammatory genes in the subcortex. Additionally, the FFAs elicit a comprehensive downregulation of inflammatory microglia/monocyte-derived macrophages and astrocyte-associated genes in the subcortical region. Functional analysis reveals inhibition of immune-related pathways and production of upstream molecules related to detrimental signaling events in post-stroke acute and subacute phases.

Novel Therapeutic Approaches to Prevent Atherothrombotic Ischemic Stroke in Patients with Carotid Atherosclerosis

Atherothrombotic stroke represents approximately 20% of all ischemic strokes. It is caused by large-artery atherosclerosis, mostly in the internal carotid artery, and it is associated with a high risk of early recurrence. After an ischemic stroke, tissue plasminogen activator is used in clinical practice, although it is not possible in all patients. In severe clinical situations, such as high carotid stenosis (≥70%), revascularization by carotid endarterectomy or by stent placement is carried out to avoid recurrences. In stroke prevention, the pharmacological recommendations are based on antithrombotic, lipid-lowering, and antihypertensive therapy. Inflammation is a promising target in stroke prevention, particularly in ischemic strokes associated with atherosclerosis. However, the use of anti-inflammatory strategies has been scarcely studied. No clinical trials are clearly successful and most preclinical studies are focused on protection after a stroke. The present review describes novel therapies addressed to counteract inflammation in the prevention of the first-ever or recurrent stroke. The putative clinical use of broad-spectrum and specific anti-inflammatory drugs, such as monoclonal antibodies and microRNAs (miRNAs) as regulators of atherosclerosis, will be outlined. Further studies are necessary to ascertain which patients may benefit from anti-inflammatory agents and how.

Mediator complex in neurological disease

Neurological diseases, including traumatic brain injuries, stroke (haemorrhagic and ischemic), and inherent neurodegenerative diseases cause acquired disability in humans, representing a leading cause of death worldwide. The Mediator complex (MED) is a large, evolutionarily conserved multiprotein that facilities the interaction between transcription factors and RNA Polymerase II in eukaryotes. Some MED subunits have been found altered in the brain, although their specific functions in neurodegenerative diseases are not fully understood. Mutations in MED subunits were associated with a wide range of genetic diseases for MED12, MED13, MED13L, MED20, MED23, MED25, and CDK8 genes. In addition, MED12 and MED23 were deregulated in the Alzheimer's Disease. Interestingly, most of the genomic mutations have been found in the subunits of the kinase module. To date, there is only one evidence on MED1 involvement in post-stroke cognitive deficits. Although the underlying neurodegenerative disorders may be different, we are confident that the signal cascades of the biological-cognitive mechanisms of brain adaptation, which begin after brain deterioration, may also differ. Here, we analysed relevant studies in English published up to June 2023. They were identified through a search of electronic databases including PubMed, Medline, EMBASE and Scopus, including search terms such as "Mediator complex", "neurological disease", "brains". Thematic content analysis was conducted to collect and summarize all studies demonstrating MED alteration to understand the role of this central transcriptional regulatory complex in the brain. Improved and deeper knowledge of the regulatory mechanisms in neurological diseases can increase the ability of physicians to predict onset and progression, thereby improving diagnostic care and providing appropriate treatment decisions.

Chemical composition, pharmacology and pharmacokinetic studies of GuHong injection in the treatment of ischemic stroke

GuHong injection is composed of safflower and N-acetyl-L-glutamine. It is widely used in clinical for cerebrovascular diseases, such as ischemic stroke and related diseases. The objective of this review is to comprehensively summarize the most recent information related to GuHong in the treatment of stroke, including chemical composition, clinical studies, potential pharmacological mechanisms and pharmacokinetics. Additionally, it examines possible scientific gaps in current study and aims to provide a reliable reference for future GuHong studies. The systematic review reveals that the chemical composition of safflower in GuHong is more than 300 chemical components in five categories. GuHong injection is primarily used in clinical applications for acute ischemic stroke and related diseases. Pharmacological investigations have indicated that GuHong acts in the early and recovery stages of ischemic stroke by anti-inflammatory, anti-oxidative stress, anti-coagulation, neuroprotective and anti-apoptotic mechanisms simultaneously. Pharmacokinetic studies found that the main exposed substances in rat plasma after GuHong administration are hydroxysafflor yellow A and N-acetyl-L-glutamine, and N-acetyl-L-glutamine could exert its pharmacological effect across the blood-brain barrier. As a combination of Chinese herb and chemical drug, GuHong injection has great value in drug research and clinical treatment, especially for ischemic stroke disease. This article represents a comprehensive and systematic review of existing studies on GuHong injection, including chemical composition, pharmacological mechanism, and pharmacokinetics, which provides reference significance for the clinical treatment of ischemic stroke with GuHong, as well as provides guidance for further study.

Development of circadian neurovascular function and its implications

The neurovascular system forms the interface between the tissue of the central nervous system (CNS) and circulating blood. It plays a critical role in regulating movement of ions, small molecules, and cellular regulators into and out of brain tissue and in sustaining brain health. The neurovascular unit (NVU), the cells that form the structural and functional link between cells of the brain and the vasculature, maintains the blood-brain interface (BBI), controls cerebral blood flow, and surveils for injury. The neurovascular system is dynamic; it undergoes tight regulation of biochemical and cellular interactions to balance and support brain function. Development of an intrinsic circadian clock enables the NVU to anticipate rhythmic changes in brain activity and body physiology that occur over the day-night cycle. The development of circadian neurovascular function involves multiple cell types. We address the functional aspects of the circadian clock in the components of the NVU and their effects in regulating neurovascular physiology, including BBI permeability, cerebral blood flow, and inflammation. Disrupting the circadian clock impairs a number of physiological processes associated with the NVU, many of which are correlated with an increased risk of dysfunction and disease. Consequently, understanding the cell biology and physiology of the NVU is critical to diminishing consequences of impaired neurovascular function, including cerebral bleeding and neurodegeneration.

Bibliometric analysis and visualized study of research on autophagy in ischemic stroke

Aims: To summarize and clarify the current research status and indicate possible future directions in the field of autophagy in ischemic stroke, we performed a comprehensive and multidimensional bibliometric analysis of the literature in this field published from 2011 to 2022. Methods: We retrieved articles on the field of autophagy in ischemic stroke published between 2011 and 2022 from Web of Science Core Collection (WOSCC). VOSviewer (version 1.6.19) and CiteSpace (version 6.2.R2 Basic) were used to identify the leading topics as well as generate visual maps of Countries/regions, organizations, authors, journals, and keyword networks in the related field. Results: A total of 568 publications were contained in this research. The journal with the most publications were Front Pharmacol, Mol Neurobiol, and Neuroscience. China was the most productive country with respect to co-authorship, with the Capital Med Univ being the organization with the most. co-authorships. In terms of authorship analysis, eight of the top 10 most contributive authors were from China. The co-occurring author keywords can be divided into three main clusters, including "protective effect of autophagy in ischemic stroke," "autophagy-targeted therapy for ischemic stroke," and "mitochondrial function in cerebral ischemia-reperfusion injury". Conclusion: This bibliometric analysis helps us reveal the current research hotspots in the research field of autophagy in ischemic stroke and guide future research directions. Subsequent trends in this special field are likely to identify and develop novel autophagy-targeted therapy strategies to effectively prevent and treat ischemic stroke.

Cynaropicrin Averts the Oxidative Stress and Neuroinflammation in Ischemic/Reperfusion Injury Through the Modulation of NF-kB

Cerebral ischemia and successive reperfusion are the prevailing cause of cerebral stroke. Currently cerebral stroke is considered to be one of the prior causes for high mortality, disability, and morbidity. Cynaropicrin, a sesquiterpene lactone, exhibits various pharmacologic properties and also has an anti-inflammatory property associated with the suppression of the key pro-inflammatory NF-κB pathway. The protective effect of cynaropicrin against oxidative stress and neuroinflammation during CIR injury through the modulation of NF-κB pathway was studied in the current investigation. The experimental rats split into 5 groups as sham-operated control group (group 1), middle cerebral artery occlusion (MCAO)-induced rats (group 2), MCAO rats treated with cynaropicrin (diluted in saline) immediately 2 h after MCAO with 5, 10, and 25 mg/kg administration orally were designated as groups 3, 4, and 5, respectively. In MCAO-induced animals, the severity of ischemic was evident by the elevated level nitrate, MDA, MMPs, inflammatory mediators, Bax, caspase-3, and NF-κB. The level of Nrf-2, antioxidant enzymes, Bcl-2, and IL-10 was reduced in the MCAO-induced animals. Treatment with cynaropicrin in dosage-based manner increased the level of antioxidant enzymes, IL-10, Nrf-2, and Bcl-2 in the animals which indicates the antioxidative effect of cynaropicrin. The level of nitrate, MDA, MMPs, proinflammatory cytokines, inflammatory mediators, Bax, caspase-3, and NF-κB was reduced in the rats treated with cynaropicrin in a dosage-based manner. Experimental animals treated with cynaropicrin in a dosage-dependent way showed a defensive mechanism against oxidative stress and neuroinflammation by inhibiting the NF-κB pathway.

H2S-RhoA/ROCK Pathway and Glial Cells in Axonal Remyelination After Ischemic Stroke

Ischemic stroke is one of the main reasons of disability and death. Stroke-induced functional deficits are mainly due to the secondary degeneration of the white matter characterized by axonal demyelination and injury of axon-glial integrity. Enhancement of the axonal regeneration and remyelination could promote the neural functional recovery. However, cerebral ischemia-induced activation of RhoA/Rho kinase (ROCK) pathway plays a crucial and harmful role in the process of axonal recovery and regeneration. Inhibition of this pathway could promote the axonal regeneration and remyelination. In addition, hydrogen sulfide (H2S) has the significant neuroprotective role during the recovery of ischemic stroke via inhibiting the inflammatory response and oxidative stress, regulating astrocyte function, promoting the differentiation of endogenous oligodendrocyte precursor cells (OPCs) to mature oligodendrocyte. Among all of these effects, promoting the formation of mature oligodendrocyte is a crucial part of axonal regeneration and remyelination. Furthermore, numerous studies have uncovered the crosstalk between astrocytes and oligodendrocyte, microglial cells and oligodendrocyte in the axonal remyelination following ischemic stroke. The purpose of this review was to discuss the relationship among H2S, RhoA/ROCK pathway, astrocytes, and microglial cells in the axonal remyelination following ischemic stroke to reveal new strategies for preventing and treating this devastating disease.

Secondary neurodegeneration following Stroke: what can blood biomarkers tell us?

Stroke is one of the leading causes of death and the primary source of disability in adults, resulting in neuronal necrosis of ischemic areas, and in possible secondary degeneration of regions surrounding or distant to the initial damaged area. Secondary neurodegeneration (SNDG) following stroke has been shown to have different pathogenetic origins including inflammation, neurovascular response and cytotoxicity, but can be associated also to regenerative processes. Aside from focal neuronal loss, ipsilateral and contralateral effects distal to the lesion site, disruptions of global functional connectivity and a transcallosal diaschisis have been reported in the chronic stages after stroke. Furthermore, SNDG can be observed in different areas not directly connected to the primary lesion, such as thalamus, hippocampus, amygdala, substantia nigra, corpus callosum, bilateral inferior fronto-occipital fasciculus and superior longitudinal fasciculus, which can be highlighted by neuroimaging techniques. Although the clinical relevance of SNDG following stroke has not been well understood, the identification of specific biomarkers that reflect the brain response to the damage, is of paramount importance to investigate in vivo the different phases of stroke. Actually, brain-derived markers, particularly neurofilament light chain, tau protein, S100b, in post-stroke patients have yielded promising results. This review focuses on cerebral morphological modifications occurring after a stroke, on associated cellular and molecular changes and on state-of-the-art of biomarkers in acute and chronic phase. Finally, we discuss new perspectives regarding the implementation of blood-based biomarkers in clinical practice to improve the rehabilitation approaches and post stroke recovery.

METTL14 regulates microglia/macrophage polarization and NLRP3 inflammasome activation after ischemic stroke by the KAT3B-STING axis

N6-methyladenosine (m6A) plays a crucial role in ischemic stroke, whereas the role of methyltransferase-like 14 (METTL14) in ischemic stroke remains unknown. A model of middle cerebral artery occlusion (MCAO) in rats and oxygen-glucose deprivation/reperfusion (OGD/R) model in HAPI cells were used to simulate ischemic stroke in vivo and in vitro. We found that METTL14 level was upregulated in microglia/macrophage after MCAO and OGD/R. METTL14 enhanced the expression of KAT3B by promoting the m6A modification of KAT3B mRNA. STING has been identified as a target for KAT3B and KAT3B increased STING expression by enhancing H3K27ac in the STING promoter. METTL14 promoted M1 polarization and NLRP3 inflammasome/pyroptosis axis by the KAT3B-STING signaling after OGD/R. METTL14 depletion relieved brain injury by inhibiting M1-like microglia/macrophage polarization and NLRP3 inflammasome/pyroptosis axis in MCAO rats. These findings indicate that METTL14 depletion relieves MCAO-induced brain injury, probably via switching microglia/macrophage from M1 towards M2 and restraining NLRP3 inflammasome/pyroptosis axis in microglia/macrophage.

Associations Between Diurnal Timing of Spinal Cord Injury and Its Etiology and Co-Morbidities

Circadian rhythms play a role in time-of-day differences in risk, presenting severity and outcomes of stroke. Injury time-of-day effects, however, on occurrence, presenting severity and acute hospital outcomes have not been yet reported in patients with neurotrauma. Therefore, acute post-spinal cord injury hospitalization records of 759 patients from the prospective NACTN registry that contained information about the time of injury were analyzed. No major demographic differences were observed between groups with time of injury between 6:00-12:00, 12:00-18:00, 18:00-24:00, or 0:00-6:00. Two etiological factors including falls or sports/recreation-related accidents showed significant effects of time of injury with peaks in the 6:00-12:00 or 18:00-24:00 groups, respectively. History of diabetes or drug abuse was also significantly related to injury timing peaking in 6:00-12:00 or 18:00-24:00 groups, respectively. ASIA score-determined presenting severity during the first week post-injury was not significantly affected by timing of injury. Pairwise comparisons, however, revealed worse motor but not sensory ASIA scores after injuries at 24:00-6:00 than any other group. These data suggest diurnal modulation of spinal cord injury risk because of specific mechanisms such as falls or sports-related accidents. Moreover, some co-morbidities may interact with those injury mechanisms as exemplified by the established risk elevation of falls in those with diabetes mellitus. Finally, while diurnal timing of the injury may modulate presenting severity, more patient records are needed to verify those effects.

Evaluation of BCAS1-positive immature oligodendrocytes after cerebral ischemic stroke and SVD

Ischemic cerebrovascular disease is an important cause of physical disability and dementia. Oligodendrocytes (OLGs), which differentiate from oligodendrocyte precursor cells (OPCs), are crucial for remyelination of the damaged brain and functional recovery. Breast carcinoma amplified sequence 1 (BCAS1) has recently been shown to be highly expressed in newly formed pre-myelinating oligodendrocytes (pre-mOLGs), while its expression level is reduced in mature OLGs. In this study, we analyzed BCAS1 expression by immunohistochemical analysis of human post-mortem brain tissue from six stroke patients (death within 2 months after stroke onset) and eight small vessel disease (SVD) patients. Control post-mortem brain tissue was from eight age-matched patients without any obvious central nervous system (CNS) pathology. The Olig2 expression in the area corresponding to the same section of the BCAS1-stained slice was analyzed to determine the total oligodendrocyte lineage. The percentage of differentiating OPCs in the oligodendrocyte lineage was calculated as the ratio of BCAS1+ to Olig2+ cells (BCAS1+/Olig2+). The stroke and SVD cases showed demyelination with decreased expression of myelin basic protein (MBP, a mature OLG marker). The stroke cases showed significantly increased numbers of early-stage BCAS1+ cells with an immature morphology and Olig2+ cells (pan-oligodendrocyte lineages) in the peri-infarct areas in both the cortex and white matter, but showed no increase in the number of late-stage BCAS1+ cells with a mature morphology. In contrast, the SVD cases showed no significant increase in Olig2+ and BCAS1+ cells. These results indicated that remyelination dysfunction could be attributed to insufficient maturation of OPCs in stroke and impaired recruitment of OPCs in SVD.

A Dynamic Balance between Neuronal Death and Clearance in an in Vitro Model of Acute Brain Injury

In in vitro models of acute brain injury, neuronal death may overwhelm the capacity for microglial phagocytosis, creating a queue of dying neurons awaiting clearance. Neurons undergoing programmed cell death are in this queue, and are the most visible and frequently quantified measure of neuronal death after injury. However, the size of this queue should be equally sensitive to changes in neuronal death and the rate of phagocytosis. Using rodent organotypic hippocampal slice cultures as a model of acute perinatal brain injury, serial imaging demonstrated that the capacity for microglial phagocytosis of dying neurons was overwhelmed for 2 weeks. Altering phagocytosis rates (e.g., by changing the number of microglia) dramatically changed the number of visibly dying neurons. Similar effects were generated when the visibility of dying neurons was altered by changing the membrane permeability for stains that label dying neurons. Canonically neuroprotective interventions, such as seizure blockade, and neurotoxic maneuvers, such as perinatal ethanol exposure, were mediated by effects on microglial activity and the membrane permeability of neurons undergoing programmed cell death. These canonically neuroprotective and neurotoxic interventions had either no or opposing effects on healthy surviving neurons identified by the ongoing expression of transgenic fluorescent proteins.SIGNIFICANCE STATEMENT In in vitro models of acute brain injury, microglial phagocytosis is overwhelmed by the number of dying cells. Under these conditions, the assumptions on which assays for neuroprotective and neurotoxic effects are based are no longer valid. Thus, longitudinal assays of healthy cells, such as serial assessment of the fluorescence emission of transgenically expressed proteins, provide more accurate estimates of cell death than do single-time point anatomic or biochemical assays of the number of dying neurons. More accurate estimates of death rates in vitro will increase the translatability of preclinical studies of neuroprotection and neurotoxicity.

Neuroprotective Effects of Vinpocetine Against Ischemia-Reperfusion Injury Via Inhibiting NLRP3 Inflammasome Signaling Pathway

Ischemic stroke is one of the main causes of serious disability and death worldwide. NLRP3 inflammasome is an intracellular pattern recognition receptor composed of polyprotein complex, which participates in mediating a series of inflammatory responses and is considered as a potential target for the treatment of ischemic stroke. Vinpocetine, a derivative of vincamine, has been widely used in the prevention and treatment of ischemic stroke. However, the therapeutic mechanism of vinpocetine is not clear, and its effect on NLRP3 inflammasome remains to be determined. In this study, we used the mouse model of transient middle cerebral artery occlusion (tMCAO) to simulate the occurrence of ischemic stroke. Different doses of vinpocetine (5, 10, 15 mg/kg/d) were injected intraperitoneally for 3 days after ischemia-reperfusion in mice. The effects of different doses of vinpocetine on the degree of ischemia-reperfusion injury in mice were observed by TTC staining and modified neurological severity score scale, and the optimal dose was determined. Then, based on this optimal dose, we observed the effects of vinpocetine on apoptosis, microglial proliferation and NLRP3 inflammasome. In addition, we compared the effects of vinpocetine and MCC950 (a specific inhibitor of NLRP3 inflammasome) on NLRP3 inflammasome. Our results show that vinpocetine can effectively reduce the infarct volume and promote the recovery of behavioral function in stroke mice, and the maximal beneficial effects were observed at the dose of 10 mg/kg/d. Vinpocetine can effectively inhibit the apoptosis of peri-infarct neurons, promote the expression of Bcl-2, inhibit the expression of Bax and Cleaved Caspase-3, and reduce the proliferation of peri-infarct microglia. In addition, vinpocetine, like MCC950, can reduce the expression of NLRP3 inflammasome. Therefore, vinpocetine can effectively alleviate the ischemia-reperfusion injury in mice, and the inhibition of NLRP3 inflammasome may be an important therapeutic mechanism of vinpocetine.

Effect of Jin three needles combined with Tong Qiao and blood activation Tang on neurological function, coagulation function and serum level in stroke patients

To investigate the efficacy and safety of Jin three needles combined with Tong Qiao Wu Blood-streaming Tang in patients with acute ischemic stroke (AIS), this retrospective study analyzed the data of patients with AIS between January 2017 and December 2022. The National Institutes of Health Stroke Scale (NIHSS) scores, blood neuron-specific enolase, S100β protein (S100β), fibrinogen (FIB), cerebral infarct volume, D-dimer (D-D), prothrombin time (PT), activated partial thromboplastin time, hypersensitive c-reactive protein (hs-CRP), serum tumor necrosis factor-α (TNF-α), and homocysteine (Hcy) were compared between the 2 groups. The treatment effect was significantly better in the observation group than in the comparison group (P < .05). The NIHSS score, neuron-specific enolase, S100β, and cerebral infarct volume were significantly lower in both groups after treatment than before treatment (P < .05). FIB and D-D levels were significantly lower and APTT and PT levels were significantly higher in both groups after treatment than before treatment (P < .05). TNF-α, hs-CRP, and Hcy were significantly lower in both groups after treatment than before treatment, and TNF-α, hs-CRP and Hcy were significantly lower in the observation group than in the comparison group (P < .05). No statistically significant difference in the incidence of adverse reactions occurred between the 2 groups (P > .05). Combining Jin three needles can improve the therapeutic effect in patients with AIS, promote the recovery of neurological function, improve coagulation function, and reduce the inflammatory response with good safety.

Vascular Dysfunctions Contribute to the Long-Term Cognitive Deficits Following COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a single-stranded RNA virus and a member of the corona virus family, primarily affecting the upper respiratory system and the lungs. Like many other respiratory viruses, SARS-CoV-2 can spread to other organ systems. Apart from causing diarrhea, another very common but debilitating complication caused by SARS-CoV-2 is neurological symptoms and cognitive difficulties, which occur in up to two thirds of hospitalized COVID-19 patients and range from shortness of concentration and overall declined cognitive speed to executive or memory function impairment. Neuro-cognitive dysfunction and "brain fog" are frequently present in COVID-19 cases, which can last several months after the infection, leading to disruption of daily life. Cumulative evidence suggests that SARS-CoV-2 affects vasculature in the extra-pulmonary systems directly or indirectly, leading to impairment of endothelial function and even multi-organ damage. The post COVID-19 long-lasting neurocognitive impairments have not been studied fully and their underlying mechanism remains elusive. In this review, we summarize the current understanding of the effects of COVID-19 on vascular dysfunction and how vascular dysfunction leads to cognitive impairment in patients.

Doxycycline inhibits dopaminergic neurodegeneration through upregulation of axonal and synaptic proteins

Doxycycline (DOX) is a widely used antibiotic that is able to cross the blood-brain barrier. Several studies have shown its neuroprotective effect against neurodegeneration and have associated it with antioxidant, anti-apoptotic, and anti-inflammatory mechanisms. We have recently demonstrated that DOX mimics nerve growth factor (NGF) signaling in PC12 cells. However, the involvement of this mechanism in the neuroprotective effect of DOX is unknown. Axonal degeneration and synaptic loss are key events at the early stages of neurodegeneration, and precede the neuronal death in neurodegenerative diseases, including Parkinson's disease (PD). Therefore, the regeneration of the axonal and synaptic network might be beneficial in PD. The effect of DOX in PC12 cells treated with the Parkinsonian neurotoxin 1-methyl-4-phenylpyridinium (MPP+) was addressed. Doxycycline reduced the inhibition of neuritogenesis induced by MPP+, even in cells deprived of NGF. The mechanism involved the upregulation of GAP-43, synapsin I, β-III-tubulin, F-actin, and neurofilament-200, proteins that are associated with axonal and synaptic plasticity. Considering the role of axonal degeneration and synaptic loss at the initial stages of PD, the recent advances in early diagnosis of neurodegeneration, and the advantages of drug repurposing, doxycycline is a promising candidate to treat PD.

Neuroinflammation in Acute Ischemic and Hemorrhagic Stroke

PURPOSE OF REVIEW

This review aims to provide an overview of neuroinflammation in ischemic and hemorrhagic stroke, including recent findings on the mechanisms and cellular players involved in the inflammatory response to brain injury.

RECENT FINDINGS

Neuroinflammation is a crucial process following acute ischemic stroke (AIS) and hemorrhagic stroke (HS). In AIS, neuroinflammation is initiated within minutes of the ischemia onset and continues for several days. In HS, neuroinflammation is initiated by blood byproducts in the subarachnoid space and/or brain parenchyma. In both cases, neuroinflammation is characterized by the activation of resident immune cells, such as microglia and astrocytes, and infiltration of peripheral immune cells, leading to the release of pro-inflammatory cytokines, chemokines, and reactive oxygen species. These inflammatory mediators contribute to blood-brain barrier disruption, neuronal damage, and cerebral edema, promoting neuronal apoptosis and impairing neuroplasticity, ultimately exacerbating the neurologic deficit. However, neuroinflammation can also have beneficial effects by clearing cellular debris and promoting tissue repair. The role of neuroinflammation in AIS and ICH is complex and multifaceted, and further research is necessary to develop effective therapies that target this process. Intracerebral hemorrhage (ICH) will be the HS subtype addressed in this review. Neuroinflammation is a significant contributor to brain tissue damage following AIS and HS. Understanding the mechanisms and cellular players involved in neuroinflammation is essential for developing effective therapies to reduce secondary injury and improve stroke outcomes. Recent findings have provided new insights into the pathophysiology of neuroinflammation, highlighting the potential for targeting specific cytokines, chemokines, and glial cells as therapeutic strategies.

Decanoic acid mitigates ischemia reperfusion injury by modulating neuroprotective, inflammatory and oxidative pathways in middle cerebral artery occlusion model of stroke in rats

OBJECTIVE

Amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) is an ionotropic transmembrane receptor for glutamate. AMPA receptor blockers have been reported to prevent neurological damage and enhance the post stroke recovery in rats. Decanoic acid, a medium-chain fatty acid, has been reported to exhibit non-competitive AMPA receptor antagonism. This study evaluated the effect of decanoic acid administered before and after ischemia reperfusion injury on neurological damage and post stroke recovery in rats.

METHODS

Middle cerebral artery occlusion (MCAo) was performed by using the intraluminal method to induce focal cerebral ischemia. Decanoic acid (120 mg/kg) was administered orally for 1 day (5-10 min post reperfusion) in one group and for 2 days (24 h pre and 5-10 min post reperfusion) in the other group. Effect on neurological damage and post stroke recovery was assessed by neurobehavioral parameters, MRI and TTC staining along with inflammatory, oxidative, apoptotic, and neuroprotective biomarkers.

RESULTS

Decanoic acid significantly reduced the MCAo induced neurological damage and infarct size. Decanoic acid treatment increased the motor coordination and grip strength. Furthermore, levels of inflammatory (TNFα, IL-1β and IL-6), oxidative stress (MDA), apoptotic (TUNEL positive cells) and neurological injury (GFAP) biomarkers were reduced after decanoic acid treatment. Anti-inflammatory cytokine (IL-10) and neuroprotective markers (NT-3, BDNF and TrkB) were found to be significantly increased with decanoic acid treatment.

CONCLUSION

This study showed protective effects of decanoic acid against ischemia reperfusion injury in rats. Anti-inflammatory, antioxidant, neuroprotective, and anti-apoptotic properties may be responsible for the beneficial effects of decanoic acid observed in the study.

miR-181a targets PTEN to mediate the neuronal injury caused by oxygen-glucose deprivation and reoxygenation

Evidence suggests that the microRNA-181 (miR-181) family performs various roles in the pathophysiology of cerebral ischemia and reperfusion injury (CIRI). MiR-181a has been identified as a critical determinant of neuronal survival. Moreover, the significance of miR-181a in controlling neuronal death after CIRI has received little attention. The objective of this study was to assess the role of miR-181a in neuronal cell injury after CIRI. To mimic the in-vitro and in-vivo CIRI, we developed an oxygen-glucose deficiency/reoxygenation (OGD/R) model in SH-SY5Y cells and a transient middle cerebral artery occlusion model in rats. MiR-181a expression was significantly higher in both in-vivo and in-vitro CIRI models. The overexpression of miR-181a increased cell damage and oxidative stress caused by OGD/R, whereas inhibition of miR-181a reduced both. PTEN has also been found to be a direct miR-181a target. PTEN overexpression reduced cell apoptosis and oxidative stress induced by miR-181a upregulation under an OGD/R condition. Furthermore, we found that the rs322931 A allele was related to increased miR-181a levels in IS peripheral blood and higher susceptibility to IS. The current results offer new insights into the understanding of the molecular pathophysiology of CIRI, as well as possible new treatment candidates.

Crocetin Regulates Functions of Neural Stem Cells to Generate New Neurons for Cerebral Ischemia Recovery

Many neurons undergo apoptosis after ischemic stroke. In the brain, neurogenesis has the potential for neuronal replacement and can be activated by external conditions to repair the injury. Crocetin (CRO), naturally extracted from the plant saffron, acts as a neuroprotective agent for ischemic stroke. However, the underlying mechanism remains unknown. In this work, the effect of CRO on neural stem cell (NSC) behaviors and subventricular zone neurogenesis is investigated. Initially, NSCs are incubated with different concentrations of CRO to detect the cell proliferation and differentiation in vitro. Second, ischemic stroke induced rats are treated with CRO using nimodipine (NMDP) as a comparison. The behavioral functions, infarcted volume, and apoptotic Nissl bodies of rats are noticeably improved after CRO-treatment, comparable to those of NMDP. In addition, the increased regional cerebral blood flow and promoted neuronal differentiation are achieved by CRO-treatment. Brain tissue examination shows significantly increased neuronal regeneration in the focal ischemic injury area. Meanwhile, the length of neurites is prolonged, indicating that CRO could potentially promote neurite extension to enhance cell-cell communication. These findings demonstrate that CRO facilitated the neuronal differentiation of NSCs by activating subventricular zone neurogenesis in damaged cortex and striatum sites to repair ischemic stroke.

Activation of TRPV4 channels promotes the loss of cellular ATP in organotypic slices of the mouse neocortex exposed to chemical ischemia

The vertebrate brain has an exceptionally high energy need. During ischemia, intracellular ATP concentrations decline rapidly, resulting in the breakdown of ion gradients and cellular damage. Here, we employed the nanosensor ATeam1.03YEMK to analyse the pathways driving the loss of ATP upon transient metabolic inhibition in neurons and astrocytes of the mouse neocortex. We demonstrate that brief chemical ischemia, induced by combined inhibition of glycolysis and oxidative phosphorylation, results in a transient decrease in intracellular ATP. Neurons experienced a larger relative decline and showed less ability to recover from prolonged (>5 min) metabolic inhibition than astrocytes. Blocking voltage-gated Na+ channels or NMDA receptors ameliorated the ATP decline in neurons and astrocytes, while blocking glutamate uptake aggravated the overall reduction in neuronal ATP, confirming the central role of excitatory neuronal activity in the cellular energy loss. Unexpectedly, pharmacological inhibition of transient receptor potential vanilloid 4 (TRPV4) channels significantly reduced the ischemia-induced decline in ATP in both cell types. Imaging with Na+ -sensitive indicator dye ING-2 furthermore showed that TRPV4 inhibition also reduced ischemia-induced increases in intracellular Na+ . Altogether, our results demonstrate that neurons exhibit a higher vulnerability to brief metabolic inhibition than astrocytes. Moreover, they reveal an unexpected strong contribution of TRPV4 channels to the loss of cellular ATP and suggest that the demonstrated TRPV4-related ATP consumption is most likely a direct consequence of Na+ influx. Activation of TRPV4 channels thus provides a hitherto unacknowledged contribution to the cellular energy loss during energy failure, generating a significant metabolic cost in ischemic conditions. KEY POINTS: In the ischemic brain, cellular ATP concentrations decline rapidly, which results in the collapse of ion gradients and promotes cellular damage and death. We analysed the pathways driving the loss of ATP upon transient metabolic inhibition in neurons and astrocytes of the mouse neocortex. Our results confirm the central role of excitatory neuronal activity in the cellular energy loss and demonstrate that neurons experience a larger decline in ATP and are more vulnerable to brief metabolic stress than astrocytes. Our study also reveals a new, previously unknown involvement of osmotically activated transient receptor potential vanilloid 4 (TRPV4) channels to the reduction in cellular ATP in both cell types and indicates that this is a consequence of TRPV4-mediated Na+ influx. We conclude that activation of TRPV4 channels provides a considerable contribution to the cellular energy loss, thereby generating a significant metabolic cost in ischemic conditions.

Glutamate-releasing BEST1 channel is a new target for neuroprotection against ischemic stroke with wide time window

Many efforts have been made to understand excitotoxicity and develop neuroprotectants for the therapy of ischemic stroke. The narrow treatment time window is still to be solved. Given that the ischemic core expanded over days, treatment with an extended time window is anticipated. Bestrophin 1 (BEST1) belongs to a bestrophin family of calcium-activated chloride channels. We revealed an increase in neuronal BEST1 expression and function within the peri-infarct from 8 to 48 h after ischemic stroke in mice. Interfering the protein expression or inhibiting the channel function of BEST1 by genetic manipulation displayed neuroprotective effects and improved motor functional deficits. Using electrophysiological recordings, we demonstrated that extrasynaptic glutamate release through BEST1 channel resulted in delayed excitotoxicity. Finally, we confirmed the therapeutic efficacy of pharmacological inhibition of BEST1 during 6-72 h post-ischemia in rodents. This delayed treatment prevented the expansion of infarct volume and the exacerbation of neurological functions. Our study identifies the glutamate-releasing BEST1 channel as a potential therapeutic target against ischemic stroke with a wide time window.

Role of the Voltage-Gated Proton Channel Hv1 in Nervous Systems

Hv1 is the only voltage-gated proton-selective channel in mammalian cells. It contains a conserved voltage-sensor domain, shared by a large class of voltage-gated ion channels, but lacks a pore domain. Its primary role is to extrude protons from the cytoplasm upon pH reduction and membrane depolarization. The best-known function of Hv1 is the regulation of cytosolic pH and the nicotinamide adenine dinucleotide phosphate oxidase-dependent production of reactive oxygen species. Accumulating evidence indicates that Hv1 is expressed in nervous systems, in addition to immune cells and others. Here, we summarize the molecular properties, distribution, and physiological functions of Hv1 in the peripheral and central nervous systems. We describe the recently discovered functions of Hv1 in various neurological diseases, including brain or spinal cord injury, ischemic stroke, demyelinating diseases, and pain. We also summarize the current advances in the discovery and application of Hv1-targeted small molecules in neurological diseases. Finally, we discuss the current limitations of our understanding of Hv1 and suggest future research directions.

Histopathological lesions induced by stroke in the encephalon

Strokes are conditions with a high degree of morbidity and mortality worldwide. These conditions profoundly affect the quality of life of patients; in addition to physical disabilities, patients present various mental disorders, such as mood disorders, anxiety, depression, behavioral disorders, fatigue, etc. Microscopic lesions of the brain parenchyma explain the clinical symptoms and correlate with the severity of the stroke. Our study consisted of the histopathological (HP) and immunohistochemical analysis of brain fragments, collected from 23 patients, with a clinical and imagistic diagnosis of stroke, who died during hospital admission. The microscopic analysis showed that both neurons and glial cells are affected in the ischemic focus. Neuronal death in the ischemic focus was mostly caused by cell necrosis and only about 10% by apoptosis. Regarding vascular lesions, it was observed that the most frequent HP lesion of intracerebral arterioles was arteriosclerosis. The lumen of the arterioles was reduced, and the vascular endothelium had a discontinuous aspect, which indicates a change in the blood-brain barrier. Sometimes the arteriole lumen was completely obstructed, with fibrinoid necrosis in the internal and middle tunic, or with the proliferation of fibroblasts and the formation of young intraluminal connective tissue. Intraparenchymal blood capillaries in the ischemic area showed endothelium discontinuities, lumen collapse, and sometimes massive perivascular edema. As for neuroinflammation, the presence of numerous neutrophils, lymphocytes, plasma cells and macrophages was found in the ischemic focus, forming a complex and inhomogeneous cellular mixture. Of the inflammatory cells present in the ischemic focus and in the ischemic penumbra area, the most numerous were the macrophages. The HP analysis showed that neuroinflammation is very complex and different in intensity from one patient to another, most likely due to associated comorbidities, age, treatment administered until death, etc.

Selenium supplementation provides potent neuroprotection following cerebral ischemia in mice

Despite progress in reperfusion therapy, functional recovery remains suboptimal in many stroke patients, with oxidative stress, inflammation, dysbiosis, and secondary neurodegeneration constituting the major hurdles to recovery. The essential trace element selenium is emerging as a promising therapeutic agent for stroke. However, although several rodent studies have shown that selenium can protect against cell loss following cerebral ischemia, no study has yet examined whether selenium can enhance long-term functional recovery. Moreover, published studies have typically reported a single mechanism of action underlying selenium-mediated stroke recovery. However, we propose that selenium is more likely to have multifaceted actions. Here, we show that selenomethionine confers a potent neuroprotective effect in a canonical filament-induced transient middle cerebral artery occlusion (tMCAO) mouse model. Post-tMCAO selenium treatment significantly reduces the cerebral infarct volume, oxidative stress, and ferroptosis and enhances post-tMCAO motor performance in the acute phase after stroke. Moreover, analysis of the gut microbiota reveals that acute selenium treatment reverses stroke-induced gut dysbiosis. Longer-term selenium supplementation activates intrinsic neuroprotective mechanisms, prevents secondary neurodegeneration, alleviates systemic inflammation, and diminishes gut microbe-derived circulating trimethylamine N-oxide. These findings demonstrate that selenium treatment even after cerebral ischemia has long-term and multifaceted neuroprotective effects, highlighting its clinical potential.

Self-healing hydrogel as an injectable implant: translation in brain diseases

Tissue engineering biomaterials are aimed to mimic natural tissue and promote new tissue formation for the treatment of impaired or diseased tissues. Highly porous biomaterial scaffolds are often used to carry cells or drugs to regenerate tissue-like structures. Meanwhile, self-healing hydrogel as a category of smart soft hydrogel with the ability to automatically repair its own structure after damage has been developed for various applications through designs of dynamic crosslinking networks. Due to flexibility, biocompatibility, and ease of functionalization, self-healing hydrogel has great potential in regenerative medicine, especially in restoring the structure and function of impaired neural tissue. Recent researchers have developed self-healing hydrogel as drug/cell carriers or tissue support matrices for targeted injection via minimally invasive surgery, which has become a promising strategy in treating brain diseases. In this review, the development history of self-healing hydrogel for biomedical applications and the design strategies according to different crosslinking (gel formation) mechanisms are summarized. The current therapeutic progress of self-healing hydrogels for brain diseases is described as well, with an emphasis on the potential therapeutic applications validated by in vivo experiments. The most recent aspect as well as the design rationale of self-healing hydrogel for different brain diseases is also addressed.

Hydrogen Attenuates Inflammation by Inducing Early M2 Macrophage Polarization in Skin Wound Healing

The heterogeneous and highly plastic cell populations of macrophages are important mediators of cellular responses during all stages of wound healing, especially in the inflammatory stage. Molecular hydrogen (H₂), which has potent antioxidant and anti-inflammatory effects, has been shown to promote M2 polarization in injury and disease. However, more in vivo time series studies of the role of M1-to-M2 polarization in wound healing are needed. In the current study, we performed time series experiments on a dorsal full-thickness skin defect mouse model in the inflammatory stage to examine the effects of H₂ inhalation. Our results revealed that H₂ could promote very early M1-to-M2 polarization (on days 2-3 post wounding, 2-3 days earlier than in conventional wound healing), without disturbing the functions of the M1 phenotype. Time series analysis of the transcriptome, blood cell counts, and multiple cytokines further indicated that peripheral blood monocytes were a source of H₂-induced M2 macrophages and that the functions of H₂ in macrophage polarization were not only dependent on its antioxidant effects. Therefore, we believe that H₂ could reduce inflammation in wound care by shifting early macrophage polarization in clinical settings.

Increasing reproducibility in preclinical stroke research: the correlation of immunofluorescence intensity measurements and Western blot analyses strongly depends on antibody clonality and tissue pre-treatment in a mouse model of focal cerebral ischemia

In the setting of stroke, ischemia not only impairs neuronal function, but also detrimentally affects the different components of the neurovascular unit, which are shown to be involved in the transition from reversible to long-lasting tissue damage. In this context, the glial proteins myelin basic protein (MBP) and the 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNP) as well as the vasculature-associated basement membrane proteins laminin and collagen IV have been identified as ischemia-sensitive elements. However, available data from immunofluorescence and Western blot analyses are often found to be contradictory, which renders interpretation of the respective data rather difficult. Therefore, the present study investigates the impact of tissue pre-treatment and antibody clonality on immunofluorescence measurements of the mentioned proteins in a highly reproducible model of permanent middle cerebral artery occlusion. Here, immunofluorescence labeling using polyclonal antibodies revealed an increased immunofluorescence intensity of MBP, CNP, laminin and collagen IV in ischemic areas, although Western blot analyses did not reveal increased protein levels. Importantly, contrary to polyclonal antibodies, monoclonal ones did not provide increased fluorescence intensities in ischemic areas. Further, we were able to demonstrate that different ways of tissue pre-treatment including paraformaldehyde fixation and antigen retrieval may not only impact on fluorescence intensity measurements in general, but rather one-sidedly affect either ischemic or unaffected tissue. Therefore, immunofluorescence intensity measurements do not necessarily correlate with the actual protein levels, especially in ischemia-affected tissue and should always be complemented by different techniques to enhance reproducibility and to hopefully overcome the translational roadblock from bench to bedside.

The interaction between intestinal microenvironment and stroke

BACKGROUND

Stroke is not only a major cause of disability but also the third leading cause of death, following heart disease and cancer. It has been established that stroke causes permanent disability in 80% of survivors. However, current treatment options for this patient population are limited. Inflammation and immune response are major features that are well-recognized to occur after a stroke. The gastrointestinal tract hosts complex microbial communities, the largest pool of immune cells, and forms a bidirectional regulation brain-gut axis with the brain. Recent experimental and clinical studies have highlighted the importance of the relationship between the intestinal microenvironment and stroke. Over the years, the influence of the intestine on stroke has emerged as an important and dynamic research direction in biology and medicine.

AIMS

In this review, we describe the structure and function of the intestinal microenvironment and highlight its cross-talk relationship with stroke. In addition, we discuss potential strategies aiming to target the intestinal microenvironment during stroke treatment.

CONCLUSION

The structure and function of the intestinal environment can influence neurological function and cerebral ischemic outcome. Improving the intestinal microenvironment by targeting the gut microbiota may be a new direction in treating stroke.

Plasma Homocysteine (Hcy) Concentration Functions as a Predictive Biomarker of SPECT-Evaluated Post-Ischemic Hyperperfusion in Acute Ischemic Stroke

Introduction

Homocysteine (Hcy) concentration has been reported to be associated with ischemic stroke. In this study, we aimed to investigate the potential of plasma Hcy in the prediction of post-ischemic hyperperfusion in AIS patients, which was diagnosed with the single-photon emission computed tomography (SPECT) method.

Methods

A total of 112 ischemic stroke patients were recruited in this study. According to whether the patients were subjected to post-ischemic hyperperfusion, all recruited subjects were divided into a post-ischemic hyperperfusion (+) group (N=48) and post-ischemic hyperperfusion (-) group (N=64). The basic demographical data, clinicopathological data and laboratory biochemical data were collected and compared. Level of homocysteine (Hcy) and cystatin-C (Cys-C) and their potential as predictive biomarker are also investigated.

Results

No significant differences were spotted between the post-ischemic hyperperfusion group (+) and post-ischemic hyperperfusion (-) group in respect to the basic demographical and clinicopathological data. And the serum Hcy levels were lower in the post-ischemic hyperperfusion (+) group. Moreover, ROC analysis indicated significant relationships between Hcy levels and the onset of post-ischemic hyperperfusion.

Conclusion

In conclusion, we validated that the plasma Hcy concentration can be used as a predictive biomarker of SPECT-evaluated post-ischemic hyperperfusion in patients suffering from acute ischemic stroke.

Identification and cross-validation of autophagy-related genes in cardioembolic stroke

Objective

Cardioembolic stroke (CE stroke, also known as cardiogenic cerebral embolism, CCE) has the highest recurrence rate and fatality rate among all subtypes of ischemic stroke, the pathogenesis of which was unclear. Autophagy plays an essential role in the development of CE stroke. We aim to identify the potential autophagy-related molecular markers of CE stroke and uncover the potential therapeutic targets through bioinformatics analysis.

Methods

The mRNA expression profile dataset GSE58294 was obtained from the GEO database. The potential autophagy-related differentially expressed (DE) genes of CE stroke were screened by R software. Protein-protein interactions (PPIs), correlation analysis, and gene ontology (GO) enrichment analysis were applied to the autophagy-related DE genes. GSE66724, GSE41177, and GSE22255 were introduced for the verification of the autophagy-related DE genes in CE stroke, and the differences in values were re-calculated by Student's t-test.

Results

A total of 41 autophagy-related DE genes (37 upregulated genes and four downregulated genes) were identified between 23 cardioembolic stroke patients (≤3 h, prior to treatment) and 23 healthy controls. The KEGG and GO enrichment analysis of autophagy-related DE genes indicated several enriched terms related to autophagy, apoptosis, and ER stress. The PPI results demonstrated the interactions between these autophagy-related genes. Moreover, several hub genes, especially for CE stroke, were identified and re-calculated by Student's t-test.

Conclusion

We identified 41 potential autophagy-related genes associated with CE stroke through bioinformatics analysis. SERPINA1, WDFY3, ERN1, RHEB, and BCL2L1 were identified as the most significant DE genes that may affect the development of CE stroke by regulating autophagy. CXCR4 was identified as a hub gene of all types of strokes. ARNT, MAPK1, ATG12, ATG16L2, ATG2B, and BECN1 were identified as particular hub genes for CE stroke. These results may provide insight into the role of autophagy in CE stroke and contribute to the discovery of potential therapeutic targets for CE stroke treatment.

The role of protein glycosylation in the occurrence and outcome of acute ischemic stroke

Acute ischemic stroke (AIS) is a serious and life-threatening disease worldwide. Despite thrombolysis or endovascular thrombectomy, a sizeable fraction of patients with AIS have adverse clinical outcomes. In addition, existing secondary prevention strategies with antiplatelet and anticoagulant drugs therapy are not able to adequately decrease the risk of ischemic stroke recurrence. Thus, exploring novel mechanisms for doing so represents an urgent need for the prevention and treatment of AIS. Recent studies have discovered that protein glycosylation plays a critical role in the occurrence and outcome of AIS. As a common co- and post-translational modification, protein glycosylation participates in a wide variety of physiological and pathological processes by regulating the activity and function of proteins or enzymes. Protein glycosylation is involved in two causes of cerebral emboli in ischemic stroke: atherosclerosis and atrial fibrillation. Following ischemic stroke, the level of brain protein glycosylation becomes dynamically regulated, which significantly affects stroke outcome through influencing inflammatory response, excitotoxicity, neuronal apoptosis, and blood-brain barrier disruption. Drugs targeting glycosylation in the occurrence and progression of stroke may represent a novel therapeutic idea. In this review, we focus on possible perspectives about how glycosylation affects the occurrence and outcome of AIS. We then propose the potential of glycosylation as a therapeutic drug target and prognostic marker for AIS patients in the future.

Rehabilitation in Animal Models of Stroke

OBJECTIVE

The purpose of this review was to evaluate the efficacy of rehabilitation strategies in animal models of stroke and their correlation with human stroke studies.

METHODS

General description of a stroke, functional recovery, and rehabilitation modalities were included from published studies in the field of animal models of cerebral ischemia and ischemia-reperfusion.

RESULTS

In stroke survivors, rehabilitation plays a significant role to improve motor function, cognition, and other subtle behaviors. Targeted pharmacological agents, including neuroprotective drugs, are helpful in animal models of stroke. However, no drug has yet been found that meets the criteria that would make it the Food and Drug Administration-approved treatment for human stroke. Instead, the rehabilitation of stroke in humans is limited to physical and occupational therapy, speech therapy, environmental enrichment, and social activities, as well as spiritual and family support.

CONCLUSION

Studies on stroke injury and the significance of stroke animals' rehabilitation, including physical and pharmacological, approaches are highlighted.

Vision for Ratiometric Nanoprobes: In Vivo Noninvasive Visualization and Readout of Physiological Hallmarks

Lesion areas are distinguished from normal tissues surrounding them by distinct physiological characteristics. These features serve as biological hallmarks with which targeted biomedical imaging of the lesion sites can be achieved. Although tremendous efforts have been devoted to providing smart imaging probes with the capability of visualizing the physiological hallmarks at the molecular level, the majority of them are merely able to derive anatomical information from the tissues of interest, and thus are not suitable for taking part in in vivo quantification of the biomarkers. Recent advances in chemical construction of advanced ratiometric nanoprobes (RNPs) have enabled a horizon for quantitatively monitoring the biological abnormalities in vivo. In contrast to the conventional probes whose dependency of output on single-signal profiles restricts them from taking part in quantitative practices, RNPs are designed to provide information in two channels, affording a self-calibration opportunity to exclude the analyte-independent factors from the outputs and address the issue. Most of the conventional RNPs have encountered several challenges regarding the reliability and sufficiency of the obtained data for high-performance imaging. In this Review, we have summarized the recent progresses in developing highly advanced RNPs with the capabilities of deriving maximized information from the lesion areas of interest as well as adapting themselves to the complex biological systems in order to minimize microenvironmental-induced falsified signals. To provide a better outlook on the current advanced RNPs, nanoprobes based on optical, photoacoustic, and magnetic resonance imaging modalities for visualizing a wide range of analytes such as pH, reactive species, and different derivations of amino acids have been included. Furthermore, the physicochemical properties of the RNPs, the major constituents of the nanosystems and the analyte recognition mechanisms have been introduced. Moreover, the alterations in the values of the ratiometric signal in response to the analyte of interest as well as the time at which the highest value is achieved, have been included for most of RNPs discussed in this Review. Finally, the challenges as well as future perspectives in the field are discussed.

Elevated neutrophil-related immune-inflammatory biomarkers in acute anterior choroidal artery territory infarction with early progression

OBJECTIVE

The anterior choroidal artery territory (AChA) infarction has a high rate of progression and poor functional prognosis. The aim of the study is to search for fast and convenient biomarkers to forecast the early progression of acute AChA infarction.

METHODS

We respectively collected 51 acute AChA infarction patients, and compared the laboratorial index between early progressive and non-progressive acute AChA infarction patients. The receiver-operating characteristics curve (ROC) analysis was used to determine the discriminant efficacy of indicators that had statistical significance.

RESULTS

The white blood cell, neutrophil, monocyte, white blood cell to high-density lipoprotein cholesterol ratio, neutrophil to high-density lipoprotein cholesterol ratio (NHR), monocyte to high-density lipoprotein cholesterol ratio, monocyte to lymphocyte ratio, neutrophil to lymphocyte ratio (NLR), and hypersensitive C-reaction protein in acute AChA infarction are significantly higher than healthy controls (P < 0.05). The NHR (P = 0.020) and NLR (P = 0.006) are remarkably higher in acute AChA infarction patients with early progression than non-progression. The area under the ROC curve of NHR, NLR, the combine of NHR and NLR are 0.689 (P = 0.011), 0.723 (P = 0.003), 0.751 (P < 0.001), respectively. But there are no significant differences in efficiency between NHR and NLR and their combined marker in predicting progression (P > 0.05).

CONCLUSION

NHR and NLR may be significant predictors of early progressive patients with acute AChA infarction, and the combination of NHR and NLR could be a preferable prognostic marker for AChA infarction with early progressive course in acute stage.

Transcutaneous Electrical Nerve Stimulation (TENS) Alleviates Brain Ischemic Injury by Regulating Neuronal Oxidative Stress, Pyroptosis, and Mitophagy

Background

As a noninvasive treatment, transcutaneous electrical nerve stimulation (TENS) has been utilized to treat various diseases in clinic. However, whether TENS can be an effective intervention in the acute stage of ischemic stroke still remains unclear. In the present study, we aimed to explore whether TENS could alleviate brain infarct volume, reduce oxidative stress and neuronal pyroptosis, and activate mitophagy following ischemic stroke.

Methods

TENS was performed at 24 h after middle cerebral artery occlusion/reperfusion (MCAO/R) in rats for 3 consecutive days. Neurological scores, the volume of infarction, and the activity of SOD, MDA, GSH, and GSH-px were measured. Moreover, western blot was performed to detect the related protein expression, including Bcl-2, Bax, TXNIP, GSDMD, caspase-1, NLRP3, BRCC3, HIF-1α, BNIP3, LC3, and P62. Real-time PCR was performed to detect NLRP3 expression. Immunofluorescence was performed to detect the levels of LC3.

Results

There was no significant difference of neurological deficit scores between the MCAO group and the TENS group at 2 h after MCAO/R operation (P > 0.05), while the neurological deficit scores of TENS group significantly decreased in comparison with MCAO group at 72 h following MACO/R injury (P < 0.05). Similarly, TENS treatment significantly reduced the brain infarct volume compared with the MCAO group (P < 0.05). Moreover, TENS decreased the expression of Bax, TXNIP, GSDMD, caspase-1, BRCC3, NLRP3, and P62 and the activity of MDA as well as increasing the level of Bcl-2, HIF-1α, BNIP3, and LC3 and the activity of SOD, GSH, and GSH-px (P < 0.05).

Conclusions

In conclusion, our results indicated that TENS alleviated brain damage following ischemic stroke via inhibiting neuronal oxidative stress and pyroptosis and activating mitophagy, possibly via the regulation of TXNIP, BRCC3/NLRP3, and HIF-1α/BNIP3 pathways.

Rhythms in barriers and fluids: Circadian clock regulation in the aging neurovascular unit

The neurovascular unit is where two very distinct physiological systems meet: The central nervous system (CNS) and the blood. The permeability of the barriers separating these systems is regulated by time, including both the 24 h circadian clock and the longer processes of aging. An endogenous circadian rhythm regulates the transport of molecules across the blood-brain barrier and the circulation of the cerebrospinal fluid and the glymphatic system. These fluid dynamics change with time of day, and with age, and especially in the context of neurodegeneration. Factors may differ depending on brain region, as can be highlighted by consideration of circadian regulation of the neurovascular niche in white matter. As an example of a potential target for clinical applications, we highlight chaperone-mediated autophagy as one mechanism at the intersection of circadian dysregulation, aging and neurodegenerative disease. In this review we emphasize key areas for future research.

Preferential delivery of lipid-ligand conjugated DNA/RNA heteroduplex oligonucleotide to ischemic brain in hyperacute stage

Antisense oligonucleotide (ASO) is a major tool used for silencing pathogenic genes. For stroke in the hyperacute stage, however, the ability of ASO to regulate genes is limited by its poor delivery to the ischemic brain owing to sudden occlusion of the supplying artery. Here we show that, in a mouse model of permanent ischemic stroke, lipid-ligand conjugated DNA/RNA heteroduplex oligonucleotide (lipid-HDO) was unexpectedly delivered 9.6 times more efficiently to the ischemic area of the brain than to the contralateral non-ischemic brain and achieved robust gene knockdown and change of stroke phenotype, despite a 90% decrease in cerebral blood flow in the 3 h after occlusion. This delivery to neurons was mediated via receptor-mediated transcytosis by lipoprotein receptors in brain endothelial cells, the expression of which was significantly upregulated after ischemia. This study provides proof-of-concept that lipid-HDO is a promising gene-silencing technology for stroke treatment in the hyperacute stage.

The Unconventional Growth Factors Cerebral Dopamine Neurotrophic Factor and Mesencephalic Astrocyte-Derived Neurotrophic Factor Promote Post-ischemic Neurological Recovery, Perilesional Brain Remodeling, and Lesion-Remote Axonal Plasticity

Considerable efforts are currently made to develop strategies that boost endogenous recovery once a stroke has occurred. Owing to their restorative properties, neurotrophic factors are attractive candidates that capitalize on endogenous response mechanisms. Non-conventional growth factors cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF) promote neuronal survival and reduce neurological deficits in the acute phase of ischemic stroke in mice. Their effects on endogenous repair and recovery mechanisms in the stroke recovery phase were so far unknown. By intracerebroventricular delivery of CDNF or MANF starting 3 days post-stroke (1 µg/day for 28 days via miniosmotic pumps), we show that delayed CDNF and MANF administration promoted functional neurological recovery assessed by a battery of behavioral tests, increased long-term neuronal survival, reduced delayed brain atrophy, glial scar formation, and, in case of CDNF but not MANF, increased endogenous neurogenesis in the perilesional brain tissue. Besides, CDNF and MANF administration increased long-distance outgrowth of terminal axons emanating from the contralesional pyramidal tract, which crossed the midline to innervate ipsilesional facial nucleus. This plasticity promoting effect was accompanied by downregulation of the axonal growth inhibitor versican and the guidance molecules ephrin B1 and B2 in the previously ischemic hemisphere at 14 dpi, which represents a sensitive time-point for axonal growth. CDNF and MANF reduced the expression of the proinflammatory cytokines IL1β and TNFα in both hemispheres. The effects of non-conventional growth factors in the ischemic brain should further be examined since they might help to identify targets for restorative stroke therapy.

Regional cerebral blood flow and brain atrophy in mild cognitive impairment and Alzheimer's disease

Objectives

A decline in the regional cerebral blood flow (CBF) is proposed to be one of the initial changes in the Alzheimer's disease process. To date, there are limited data on the correlation between CBF decline and gray matter atrophy in mild cognitive impairment (MCI) and AD patients. to investigate the association between CBF with the gray matter structural parameters such as cortical volume, surface area, and thickness in AD, MCI, and healthy controls (HC).

Methods

Data from three groups of participants including 39 HC, 82 MCI, and 28 AD subjects were obtained from the Alzheimer's disease Neuroimaging Initiative (ADNI). One-way ANOVA and linear regression were used to compare data and find a correlation between structural parameters such as cortical volume, surface area, and thickness and CBF which measured by arterial spin labeling (ASL)-MRI.

Results

Our findings revealed a widespread significant correlation between the CBF and structural parameters in temporal, frontal, parietal, occipital, precentral gyrus, pericalcarine cortex, entorhinal cortex, supramarginal gyrus, fusiform, precuneus, and pallidum.

Conclusion

CBF decline may be a useful biomarker for MCI and AD and accurately reflect the structural changes related to AD. According to the present results, CBF decline, as measured by ASL-MRI, is correlated with lower measures of structural parameters in AD responsible regions. It means that CBF decline may reflect AD-associated atrophy across disease progression and is also used as an early biomarker for AD and MCI diagnosis.

Carnosol inhibits cerebral ischemia-reperfusion injury by promoting AMPK activation

BACKGROUND

Carnosol is a phytopolyphenol (diterpene) found and extracted from plants of Mediterranean diet, which has anti-tumor, anti-inflammatory and antioxidant effects. However, its role in ischemic stroke has not been elucidated.

METHODS

Primary neurons subjected to oxygen-glucose deprivation (OGD) was used to investigate the effect of carnosol in vitro. A mouse MCAO model was used to evaluate the effect of carnosol on ischemic stroke in vivo. The mRNA level of inflammatory and apoptosis-related genes was determined by RT-PCR. The protein level of total and phosphorylated AMPK was determined by WB. H&E and Immunofluorescent assay was used to investigate the necrosis, inflammation and apoptosis in brain tissue.

RESULTS

Carnosol protected the activity of primary neurons subjected to oxygen-glucose deprivation (OGD) in vitro, as well as inhibited inflammation and apoptosis. Furthermore, carnosol could significantly reduce the infarct and edema volume and protect against neurological deficit in vivo, and had a significant inhibitory effect on brain neuroinflammation and apoptosis. Mechanically, carnosol could activate AMPK, and the effect of carnosol on cerebral ischemia-reperfusion injury cell model could be abolished by AMPK phosphorylation inhibitor.

CONCLUSION

Carnosol has a protective effect on ischemic stroke, and this effect is achieved through AMPK activation. Our study demonstrates the protective effect of carnosol on cerebral ischemia-reperfusion injury and provides a new perspective for the clinical treatment of ischemic stroke.