Cell Death Mechanisms in Stroke and Novel Molecular and Cellular Treatment Options

LncRNA PEG11as silencing sponges miR-874-3p to alleviate cerebral ischemia stroke via regulating autophagy in vivo and in vitro

Long non-coding RNAs (lncRNAs) are reportedly involved in the regulation of physiological and pathophysiological processes. However, the potential role of lncRNAs in stroke remains largely undefined. Here, RNA-Seq analysis of lncRNAs found that the lncRNA PEG11as (PEG11as) levels were significantly increased in ischemic brain tissue in a transient middle cerebral artery occlusion/reperfusion (tMCAO/R) mouse model of stroke. To explore the role of PEG11as in stroke, the lentivirus containing PEG11as silencing construct(siRNA-PEG11as) was microinjected intracerebroventricularly into male or transfected to N2a cells and then exposed to tMCAO/R or oxygen-glucose deprivation/reoxygenation (OGD/R). Knockdown of PEG11as expression significantly reduced infarct volume, alleviated neuronal deficits and inhibited neuronal apoptosis in tMCAO/R mice. Mechanistically, as an endogenous microRNA-874-3p (miR-874-3p) sponge, PEG11as silencing inhibited miR-874-3p activity, resulting in downregulation of ATG16L1 expression and subsequent inhibition of neuronal apoptosis by regulating autophagy. Overall, the results of this current study indicate that PEG11as is involved in the pathophysiology of cerebral ischemia, thus providing translational evidence that PEG11as can be envisioned as a novel biomarker or/and therapeutic target for stroke.

Central nervous system injury meets nanoceria: opportunities and challenges

Central nervous system (CNS) injury, induced by ischemic/hemorrhagic or traumatic damage, is one of the most common causes of death and long-term disability worldwide. Reactive oxygen and nitrogen species (RONS) resulting in oxidative/nitrosative stress play a critical role in the pathological cascade of molecular events after CNS injury. Therefore, by targeting RONS, antioxidant therapies have been intensively explored in previous studies. However, traditional antioxidants have achieved limited success thus far, and the development of new antioxidants to achieve highly effective RONS modulation in CNS injury still remains a great challenge. With the rapid development of nanotechnology, novel nanomaterials provided promising opportunities to address this challenge. Within these, nanoceria has gained much attention due to its regenerative and excellent RONS elimination capability. To promote its practical application, it is important to know what has been done and what has yet to be done. This review aims to present the opportunities and challenges of nanoceria in treating CNS injury. The physicochemical properties of nanoceria and its interaction with RONS are described. The applications of nanoceria for stroke and neurotrauma treatment are summarized. The possible directions for future application of nanoceria in CNS injury treatment are proposed.

Association between high-sensitivity C-reactive protein, functional disability, and stroke recurrence in patients with acute ischaemic stroke: A mediation analysis

Background

Post-stroke inflammation biomarker high-sensitivity C-reactive protein (hsCRP) increases cerebral infarct size and results in functional disability directly, it also contributes to the formation and maturation of atherosclerotic plaques, which increase the risk of stroke recurrence and results in functional disability indirectly. However, no study has quantified how much functional disability was mediated by stroke recurrence.

Methods

Patients with acute ischaemic stroke within 7 days and admitted to 169 hospitals in the Third China National Stroke Registry were analyzed. Blood samples were collected within 24 h of admission. Stroke recurrence and functional disability (defined as a modified Rankin scale score ≥ 2) were assessed via face-to-face interviews at three months. Mediation analysis under the counterfactual framework was performed to examine the potential causal chain in which stroke recurrence may mediate the relationship between hsCRP and functional outcome. Sensitivity analyses were performed across different subgroups and on different scales of hsCRP measurement.

Findings

Of the 7603 analyzed patients (mean [SD] age, 62.3 [11.3] years; 2392 [31.5%] women), the median (interquartile range [IQR]) of NIHSS score was 3.0 (1.0–6.0). The median (IQR) level of hsCRP was 1.73 (0.81–4.38) mg/L. A total of 496 (6.5%) cases of stroke recurrence and 1884 (24.8%) cases of functional disability were observed at the 90-day follow-up. Each SD increase in the concentration of hsCRP was associated with an increased risk of stroke recurrence (adjusted odds ratio [aOR], 1.11; 95% CI, 1.04–1.18) and disability (aOR, 1.14; 95% CI, 1.08–1.20) within 90 days. Of 1884 functionally disabled patients, only 16.0 % (n = 302) of patients experienced stroke recurrence before functional disability. Stroke recurrence during follow-up explained 16.52% (95% CI, 5.79%–27.25%) of the relationship between hsCRP and functional disability. Sensitivity analyses in different subgroups and on different scales of hsCRP measurement showed comparable results.

Interpretation

Stroke recurrence mediates less than 20% of the association between hsCRP and functional disability at 90 days among patients with acute ischaemic stroke. In addition to typical secondary prevention strategies for preventing stroke recurrence, more attention should be paid to novel anti-inflammatory therapy to improve functional outcomes.

Funding

Beijing Natural Science Foundation, the National Key R&D Program of China, the National Natural Science Foundation of China, and the Beijing Municipal Science & Technology Commission.

Analgecine protects against cerebral ischemia-reperfusion through apoptosis inhibition and anti-neuroinflammation in rats

Stroke influence the quality of life of patients and leave big public health issues as acute cerebrovascular disease all over the world. Analgecine (AGC) relieves pain and accelerates repair of nerve injury. This current study aims to observe the pharmacological effects and related mechanisms of AGC in cerebral ischemic stroke among middle cerebral artery ischemia-reperfusion (MCAO) rats. After seven days of AGC administration, motor function was enhanced as evidenced by the prehensile traction test. Morphological ameliorations were observed by immunohistochemistry analysis. The protein expression levels of HSP70, Bcl-2, Bax, TRAF-6, MyD88, BDNF, NGF, pCREB, CREB, pTrkB, TrkB, pAKT and AKT were estimated by western blot. Meanwhile, AGC alleviated MCAO-induced inflammation chiefly by decreasing inflammatory cytokines in rat brain tissues. These results above suggested that MCAO-caused brain infarction was obviously alleviated by AGC. The immunohistochemistry data showed that AGC reduced neuronal injury and apoptosis, and inhibited microglia and astrocytes activation. The protein results suggested the expression of apoptosis-relevant proteins decreased among AGC treated groups and the neurotrophin related proteins were obviously enhanced by CREB/BDNF/TrkB/AKT and HSP70/Bcl-2/Bax pathways. Collectively, the results demonstrated that AGC primarily promoted neuro-nutrition, reduced the injury of nerve apoptosis and ameliorated neuroinflammation. In summary, AGC played a neuroprotective role, which had provided reliable evidence for AGC to be a potential drug in treating stroke.

Resveratrol pretreatment protects neurons from oxygen-glucose deprivation/reoxygenation and ischemic injury through inhibiting ferroptosis

Ferroptosis, a newly discovered iron-dependent cell death, is involved in brain ischemia-reperfusion injury. Iron scavengers or ferroptosis inhibitors could reduce infarct volume and improve neurological function in mice. Resveratrol has neuroprotective and neurorestorative effects. However, it is unclear whether resveratrol can play a neuroprotective role via inhibiting ferroptosis. Our study showed that resveratrol pretreatment had a similar effect with ferrostatin‑1, which inhibited neuronal ferroptosis-related changes, such as iron overload, damages of oxidation-reduction system, and destruction of mitochondrial structure, after oxygen-glucose deprivation/reoxygenation (OGD/R) and application of ferroptosis inducers. In addition, middle cerebral artery occlusion/reperfusion (MCAO/R) injury in vivo also induced ferroptosis, and resveratrol pretreatment could inhibit ferroptosis and reduce degenerative neurons, cerebral ischemic damage and infarction volume. Our results are the first to indicate that resveratrol pretreatment might inhibit ferroptosis induced by OGD/R and ferroptosis inducers in neurons, and MCAO/R in rats.

The Development of Novel Drug Treatments for Stroke Patients: A Review

Acute ischemic stroke is a critical condition that can result in disability and death. The consequences of this medical condition depend on various factors, including the size of the stroke, affected brain region, treatment onset, and the type of treatment. The primary objective of stroke treatment is to restart ischemic penumbra tissue perfusion and reduce infarct volume by sustaining blood flow. Recent research on the condition's pathological pathways and processes has significantly improved treatment options beyond restoring perfusion. Many studies have concentrated on limiting injury severity via the manipulation of molecular mechanisms of ischemia, particularly in animal research. This article reviews completed and ongoing research on the development of acute ischemic stroke drugs. This study focuses on three main categories of antithrombotic drugs, thrombolytic drugs, and neuroprotective agents. The paper outlines findings from animal and clinical trials and explores the working mechanisms of these drugs.

An Emerging Frontier in Intercellular Communication: Extracellular Vesicles in Regeneration

Regeneration requires cellular proliferation, differentiation, and other processes that are regulated by secreted cues originating from cells in the local environment. Recent studies suggest that signaling by extracellular vesicles (EVs), another mode of paracrine communication, may also play a significant role in coordinating cellular behaviors during regeneration. EVs are nanoparticles composed of a lipid bilayer enclosing proteins, nucleic acids, lipids, and other metabolites, and are secreted by most cell types. Upon EV uptake by target cells, EV cargo can influence diverse cellular behaviors during regeneration, including cell survival, immune responses, extracellular matrix remodeling, proliferation, migration, and differentiation. In this review, we briefly introduce the history of EV research and EV biogenesis. Then, we review current understanding of how EVs regulate cellular behaviors during regeneration derived from numerous studies of stem cell-derived EVs in mammalian injury models. Finally, we discuss the potential of other established and emerging research organisms to expand our mechanistic knowledge of basic EV biology, how injury modulates EV biogenesis, cellular sources of EVs in vivo, and the roles of EVs in organisms with greater regenerative capacity.

Neuronal Death Mechanisms and Therapeutic Strategy in Ischemic Stroke

Ischemic stroke caused by intracranial vascular occlusion has become increasingly prevalent with considerable mortality and disability, which gravely burdens the global economy. Current relatively effective clinical treatments are limited to intravenous alteplase and thrombectomy. Even so, patients still benefit little due to the short therapeutic window and the risk of ischemia/reperfusion injury. It is therefore urgent to figure out the neuronal death mechanisms following ischemic stroke in order to develop new neuroprotective strategies. Regarding the pathogenesis, multiple pathological events trigger the activation of cell death pathways. Particular attention should be devoted to excitotoxicity, oxidative stress, and inflammatory responses. Thus, in this article, we first review the principal mechanisms underlying neuronal death mediated by these significant events, such as intrinsic and extrinsic apoptosis, ferroptosis, parthanatos, pyroptosis, necroptosis, and autophagic cell death. Then, we further discuss the possibility of interventions targeting these pathological events and summarize the present pharmacological achievements.

Mechanism of cell death pathways in status epilepticus and related therapeutic agents

The most severe form of epilepsy, status epilepticus (SE), causes brain damage and results in the development of recurring seizures. Currently, the management of SE remains a clinical challenge because patients do not respond adequately to conventional treatments. Evidence suggests that neural cell death worsens the occurrence and progression of SE. The main forms of cell death are apoptosis, necroptosis, pyroptosis, and ferroptosis. Herein, these mechanisms of neuronal death in relation to SE and the alleviation of SE by potential modulators that target neuronal death have been reviewed. An understanding of these pathways and their possible roles in SE may assist in the development of SE therapies and in the discovery of new agents.

Guhong injection promotes post-stroke functional recovery via attenuating cortical inflammation and apoptosis in subacute stage of ischemic stroke

BACKGROUND

As a leading cause of death and disability, alternative therapies for stroke are still limited by its complicated pathophysiological manifestations. Guhong injection (GHI), consisting of safflower aqueous extract and aceglutamide, has been widely applied for the clinical treatment of cerebrovascular diseases, especially ischemic stroke and post-stroke recovery, in China. Recently, a series of studies have reported the positive effect of GHI against cerebral ischemia/reperfusion injury via targeting various molecular mechanisms. However, questions remain on whether treatment with GHI contributes to better functional recovery after stroke and if so, the potential mechanisms and active substances.

PURPOSE

The aim of this work was to explore the potential therapeutic possibilities of GHI for the neurological and behavioral recovery after stroke and to investigate the underlying molecular mechanisms as well as active substances.

METHODS

The neural and motor deficits as well as cortical lesions after GHI treatment were investigated in a mouse model of transient ischemic stroke. Based on the substance identification of GHI, network pharmacology combined with an experimental verification method was used to systematically decipher the biological processes and signaling pathways closely related to GHI intervention in response to post-stroke functional outcomes. Subsequently, ingenuity pathway analysis (IPA) analysis was performed to determine the anti-stroke active substances targeting to the hub targets involved in the significant molecular pathways regulated by GHI treatment.

RESULTS

Therapeutically, administration of GHI observably ameliorated the post-stroke recovery of neural and locomotor function as well as reduced infarct volume and histopathological damage to the cerebral cortex in subacute stroke mice. According to 26 identified or tentatively characterized substances in GHI, the compound-target-pathway network was built. Bioinformatics analysis suggested that inflammatory and apoptotic pathways were tightly associated with the anti-stroke effect of GHI. Based on protein-protein interaction network analysis, the hub targets (such as NF-κB p65, TNF-α, IL-6, IL-1β, Bax, Bcl-2, and Caspase-3) involved in inflammation and apoptosis were selected. On the one hand, immunofluorescence and ELISA results showed that GHI (10 ml/kg) treatment obviously reduced NF-κB p65 nuclear translocation as well as decreased the abnormally elevated concentrations of proinflammatory cytokines (TNF-α, IL-6, and IL-1β) in damaged cortex tissues. On the other hand, GHI (10 ml/kg) treatment significantly downregulated the number of TUNEL-positive apoptotic cells in ischemic cortex and effectively restored the abnormal expression of Bax, Bcl-2, and Caspase-3. Based on the results of IPA, hydroxysafflor yellow A, baicalin, scutellarin, gallic acid, syringin, chlorogenic acid, kaempferol, kaempferol-3-O-β-rutinoside, and rutin acted synergistically on core targets, which could be considered as the active substances of GHI.

CONCLUSION

Overall, the current findings showed that the beneficial action of GHI on improving post-stroke functional recovery of subacute stroke mice partly via the modulation of cortical inflammation and apoptosis. These findings not only provide a reliable reference for the clinical application of GHI, but also shed light on a promising alternative therapeutic strategy for ischemic stroke patients.

Evaluating iron deposition in gray matter nuclei of patients with unilateral middle cerebral artery stenosis using quantitative susceptibility mapping

Iron mediated oxidative stress is involved in the process of brain injury after long-term ischemia. While increased iron deposition in the affected brain regions was observed in animal models of ischemic stroke, potential changes in the brain iron content in clinical patients with cerebral ischemia remain unclear. Quantitative susceptibility mapping (QSM), a non-invasive magnetic resonance imaging technique, can be used to evaluate iron content in the gray matter (GM) nuclei reliably. In this study, we aimed to quantitatively evaluate iron content changes in GM nuclei of patients with long-term unilateral middle cerebral artery (MCA) stenosis/occlusion-related cerebral ischemia using QSM. Forty-six unilateral MCA stenosis/occlusion patients and 38 age-, sex- and education-matched healthy controls underwent QSM. Clinical variables of history of hypertension, diabetes, hyperlipidemia, hyperhomocysteinemia, smoking, and drinking in all patients were evaluated. The iron-related susceptibility of GM nucleus subregions, including the bilateral caudate nucleus (CN), putamen (PU), globus pallidus (GP), thalamus, substantia nigra (SN), red nucleus, and dentate nucleus, was assessed. Susceptibility was compared between the bilateral GM nuclei in patients and controls. Receiver operating characteristic curve analysis was used to evaluate the efficacy of QSM susceptibility in distinguishing patients with unilateral MCA stenosis/occlusion from healthy controls. Multiple linear regression analysis was used to evaluate the relationship between ipsilateral susceptibility levels and clinical variables. Except for the CN, the susceptibility in most bilateral GM nucleus subregions was comparable in healthy controls, whereas for patients with unilateral MCA stenosis/occlusion, the ipsilateral PU, GP, and SN exhibited significantly higher susceptibility than the contralateral side (all P < 0.05). Compared with controls, susceptibility of the ipsilateral PU, GP, and SN and of contralateral PU in patients were significantly increased (all P < 0.05). The area under the curve (AUC) was greater for the ipsilateral PU than for the GP and SN (AUC = 0.773, 0.662 and 0.681; all P < 0.05). Multiple linear regression analysis showed that the increased susceptibility of the ipsilateral PU was significantly associated with hypertension, of the ipsilateral GP associated with smoking, and of the ipsilateral SN associated with diabetes (all P < 0.05). Our findings provide support for abnormal iron accumulation in the GM nuclei after chronic MCA stenosis/occlusion and its correlation with some cerebrovascular disease risk factors. Therefore, iron deposition in the GM nuclei, as measured by QSM, may be a potential biomarker for long-term cerebral ischemia.

Extracellular vesicles from bone marrow stromal cells reduce the impact of stroke on glial cell activation and blood brain-barrier permeability via a putative miR-124/PRX1 signaling pathway

Ischemic stroke (IS) is a cerebrovascular disease caused by cerebral infarction and cerebral artery occlusion. In this study we proposed that EVs from bone marrow stromal cells (BMSCs) could reduce the impact of stroke by reducing the resultant glial cell activation and blood-brain barrier (BBB) leak. We furthermore investigated some of the signaling mechanisms. The transient middle cerebral artery occlusion (t-MCAO) mouse model was established. The behavioral deficits and neuronal damage were verified using Bederson's scale and the 28-point neurological score. The area of cerebral infarction was detected. The expressions of astrocytes/microglia markers and BBB permeability were evaluated by 2, 3,5-triphenyltetrazolium chloride (TTC) staining. The internalization of EVs by astrocytes/microglia in the peripheral area was detected by fluorescence labeling. The expressions of astrocyte/microglia markers were measured by RT-qPCR. Levels of TNF-α and IL-1β in microglia were detected by ELISA. BBB permeability was evaluated. The downstream target genes and pathway of miR-124 were analyzed. Microglia/astrocytes were treated by oxygen-glucose deprivation reoxygenation (OGD/R). OGD/R microglia/astrocyte conditioned medium was used to culture bEnd.3 cells. The transendothelial electric resistance (TEER) of bEnd.3 cells was measured and BBB permeability was characterized. Our results suggested that EVs from BMSCs can indeed reduce the extent of stroke-mediated damage, and evidenced that these effects are mediated via expression of the non-coding RNA, miR-124 that may act via the peroxiredoxin 1 (PRX1). Our results provided further motivation to pursue the use of modified EVs as a treatment option for neurological diseases.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

Emerging Roles for the Orphan GPCRs, GPR37 and GPR37 L1, in Stroke Pathophysiology

Recent studies have shed light on the diverse and complex roles of G-protein coupled receptors (GPCRs) in the pathophysiology of stroke. These receptors constitute a large family of seven transmembrane-spanning proteins that play an intricate role in cellular communication mechanisms which drive both tissue injury and repair following ischemic stroke. Orphan GPCRs represent a unique sub-class of GPCRs for which no natural ligands have been found. Interestingly, the majority of these receptors are expressed within the central nervous system where they represent a largely untapped resource for the treatment of neurological diseases. The focus of this review will thus be on the emerging roles of two brain-expressed orphan GPCRs, GPR37 and GPR37 L1, in regulating various cellular and molecular processes underlying ischemic stroke.

Long non-coding RNA TTTY15 sponges miR-520a-3p to exacerbate neural apoptosis induced by cerebral ischemia/reperfusion via targeting IRF9 in vivo and in vitro

BACKGROUND

Studies have proven that as competing endogenous RNAs (ceRNAs), long non-coding RNAs (lncRNAs) play vital roles in regulating RNA transcripts in ischemic stroke. It has been reported that TTTY15, a lncRNA, is dysregulated in cardiomyocytes after ischemic injury. We intended to explore the potential regulating mechanism of TTTY15 in ischemic stroke.

METHODS

TTTY15 and miR-520a-3p levels in vivo were measured in the cerebral ischemia/reperfusion (I/R) model. Cell apoptosis was measured by flow cytometry. To manifest TTTY15 functions in I/R injury, Neuro 2a (N2a) cells were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) and treated with si-NC, pcDNA3.1-NC, si-TTTY15 or pcDNA3.1-TTTY15.

RESULTS

TTTY15 expression was elevated and miR-520a-3p expression was declined in mouse brains exposed to I/R and in N2a cells exposed to OGD/R. Bioinformatics analyses predicted the binding sites of miR-520a-3p in the 3'-UTRs of interferon regulatory factor 9 (IRF9) and TTTY15. Luciferase reporter assay exhibited that TTTY15 bound to miR-520a-3p directly and IRF9 was targeted by miR-520a-3p. MiR-520a-3p overexpression diminished N2a cell apoptosis caused by OGD/R. TTTY15 overexpression antagonized the inhibitory impacts of miR-520a-3p on IRF9 expression and apoptosis after OGD/R, while TTTY15 knockdown enhanced the inhibitory impacts of miR-520a-3p. Additionally, TTTY15 knockdown alleviated brain damages and neurological deficits induced by I/R in vivo. Our results revealed that TTTY15 modulated IRF9 via acting as a ceRNA for miR-520a-3p.

CONCLUSION

The study revealed the roles of TTTY15/miR-520a-3p/IRF9 signaling pathway in regulating cerebral ischemia/reperfusion injury.

Identification of Novel Circulating miRNAs in Patients with Acute Ischemic Stroke

Ischemic strokes are associated with significant morbidity and mortality, but currently there are no reliable prognostic or diagnostic blood biomarkers. MicroRNAs (miRNAs) regulate various molecular pathways and may be used as biomarkers. Using RNA-Seq, we conducted comprehensive circulating miRNA profiling in patients with ischemic stroke compared with healthy controls. Samples were collected within 24 h of clinical diagnosis. Stringent analysis criteria of discovery (46 cases and 95 controls) and validation (47 cases and 96 controls) cohorts led to the identification of 10 differentially regulated miRNAs, including 5 novel miRNAs, with potential diagnostic significance. Hsa-miR-451a was the most significantly upregulated miRNA (FC; 4.8, FDR; 3.78 × 10⁻⁸⁵), while downregulated miRNAs included hsa-miR-574-5p and hsa-miR-142-3p, among others. Importantly, we computed a multivariate classifier based on the identified miRNA panel to differentiate between ischemic stroke patients and healthy controls, which showed remarkably high sensitivity (0.94) and specificity (0.99). The area under the ROC curve was 0.97 and it is superior to other current available biomarkers. Moreover, in samples collected one month following stroke, we found sustained upregulation of hsa-miR-451a and downregulation of another 5 miRNAs. Lastly, we report 3 miRNAs that were significantly associated with poor clinical outcomes of stroke, as defined by the modified Rankin scores. The clinical translation of the identified miRNA panel may be explored further.

Role of Semaphorins in Ischemic Stroke

Ischemic stroke is one of the major causes of neurological morbidity and mortality in the world. Although the management of ischemic stroke has been improved significantly, it still imposes a huge burden on the health and property. The integrity of the neurovascular unit (NVU) is closely related with the prognosis of ischemic stroke. Growing evidence has shown that semaphorins, a family of axon guidance cues, play a pivotal role in multiple pathophysiological processes in NVU after ischemia, such as regulating the immune system, angiogenesis, and neuroprotection. Modulating the NVU function via semaphorin signaling has a potential to develop a novel therapeutic strategy for ischemic stroke. We, therefore, review recent progresses on the role of semphorin family members in neurons, glial cells and vasculature after ischemic stroke.

Considerations about Hypoxic Changes in Neuraxis Tissue Injuries and Recovery

Hypoxia represents the temporary or longer-term decrease or deprivation of oxygen in organs, tissues, and cells after oxygen supply drops or its excessive consumption. Hypoxia can be (para)-physiological-adaptive-or pathological. Thereby, the mechanisms of hypoxia have many implications, such as in adaptive processes of normal cells, but to the survival of neoplastic ones, too. Ischemia differs from hypoxia as it means a transient or permanent interruption or reduction of the blood supply in a given region or tissue and consequently a poor provision with oxygen and energetic substratum-inflammation and oxidative stress damages generating factors. Considering the implications of hypoxia on nerve tissue cells that go through different ischemic processes, in this paper, we will detail the molecular mechanisms by which such structures feel and adapt to hypoxia. We will present the hypoxic mechanisms and changes in the CNS. Also, we aimed to evaluate acute, subacute, and chronic central nervous hypoxic-ischemic changes, hoping to understand better and systematize some neuro-muscular recovery methods necessary to regain individual independence. To establish the link between CNS hypoxia, ischemic-lesional mechanisms, and neuro-motor and related recovery, we performed a systematic literature review following the" Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA") filtering method by interrogating five international medical renown databases, using, contextually, specific keywords combinations/"syntaxes", with supplementation of the afferent documentation through an amount of freely discovered, also contributive, bibliographic resources. As a result, 45 papers were eligible according to the PRISMA-inspired selection approach, thus covering information on both: intimate/molecular path-physiological specific mechanisms and, respectively, consequent clinical conditions. Such a systematic process is meant to help us construct an article structure skeleton giving a primary objective input about the assembly of the literature background to be approached, summarised, and synthesized. The afferent contextual search (by keywords combination/syntaxes) we have fulfilled considerably reduced the number of obtained articles. We consider this systematic literature review is warranted as hypoxia's mechanisms have opened new perspectives for understanding ischemic changes in the CNS neuraxis tissue/cells, starting at the intracellular level and continuing with experimental research to recover the consequent clinical-functional deficits better.

Modes of Brain Cell Death Following Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a devastating form of stroke with high rates of mortality and morbidity. It induces cell death that is responsible for neurological deficits postinjury. There are no therapies that effectively mitigate cell death to treat ICH. This review aims to summarize our knowledge of ICH-induced cell death with a focus on apoptosis and necrosis. We also discuss the involvement of ICH in recently described modes of cell death including necroptosis, pyroptosis, ferroptosis, autophagy, and parthanatos. We summarize treatment strategies to mitigate brain injury based on particular cell death pathways after ICH.

Features of the cytoprotective effect of selenium nanoparticles on primary cortical neurons and astrocytes during oxygen-glucose deprivation and reoxygenation

The study is aimed at elucidating the effect of selenium nanoparticles (SeNPs) on the death of cells in the primary culture of mouse cerebral cortex during oxygen and glucose deprivation (OGD). A primary cell culture of the cerebral cortex containing neurons and astrocytes was subjected to OGD and reoxygenation to simulate cerebral ischemia-like conditions in vitro. To evaluate the neuroprotective effect of SeNPs, cortical astrocytes and neurons were incubated for 24 h with SeNPs, and then subjected to 2-h OGD, followed by 24-h reoxygenation. Vitality tests, fluorescence microscopy, and real-time PCR have shown that incubation of primary cultured neurons and astrocytes with SeNPs at concentrations of 2.5–10 µg/ml under physiological conditions has its own characteristics depending on the type of cells (astrocytes or neurons) and leads to a dose-dependent increase in apoptosis. At low concentration SeNPs (0.5 µg/ml), on the contrary, almost completely suppressed the processes of basic necrosis and apoptosis. Both high (5 µg/ml) and low (0.5 µg/ml) concentrations of SeNPs, added for 24 h to the cells of cerebral cortex, led to an increase in the expression level of genes Bcl-2, Bcl-xL, Socs3, while the expression of Bax was suppressed. Incubation of the cells with 0.5 µg/ml SeNPs led to a decrease in the expression of SelK and SelT. On the contrary, 5 µg/ml SeNPs caused an increase in the expression of SelK, SelN, SelT, SelP. In the ischemic model, after OGD/R, there was a significant death of brain cells by the type of necrosis and apoptosis. OGD/R also led to an increase in mRNA expression of the Bax, SelK, SelN, and SelT genes and suppression of the Bcl-2, Bcl-xL, Socs3, SelP genes. Pre-incubation of cell cultures with 0.5 and 2.5 µg/ml SeNPs led to almost complete inhibition of OGD/R-induced necrosis and greatly reduced apoptosis. Simultaneously with these processes we observed suppression of caspase-3 activation. We hypothesize that the mechanisms of the protective action of SeNPs involve the activation of signaling cascades recruiting nuclear factors Nrf2 and SOCS3/STAT3, as well as the activation of adaptive pathways of ESR signaling of stress arising during OGD and involving selenoproteins SelK and SelT, proteins of the Bcl-2 family ultimately leading to inactivation of caspase-3 and inhibition of apoptosis. Thus, our results demonstrate that SeNPs can act as neuroprotective agents in the treatment of ischemic brain injuries.

Cerebroprotective effect of Aloe Emodin: In silico and in vivo studies

This study involved cerebroprotective potential of aloe emodin (AE) by in silico molecular docking analysis against various cerebrotoxic proteins followed by in vivo activity on multiple occlusions and reperfusion of bilateral carotid arteries (MO/RCA) induced cerebral injury in experimental rats. Molecular docking studies were carried out to evaluate the binding affinity (or binding interaction) between AE and various proteins involved in apoptosis such as caspase-3 (CASP3) and Bcl-2-associated X protein (BAX), and proteins involved in inflammation such as interleukin-6 (IL-6), tumor necrosis factor α (TNF α), nitric oxide synthase (NOS), acid-sensing ion channel (ASIC) and glutamate receptor (GR) involved in cerebral stroke, and results were compared with that of standard drugs, minocycline, quercetin, and memantine. Cerebral ischemic reperfusion induced by MO/RCA was assessed for 10 mins reperfusion period as one cycle, and the experiment was conducted for up to 3 cycles in rats. After completion of 3 cycles, the rats were subjected to ethically acceptable animal euthanasia followed by isolation of the brains which were studied for the size of cerebral infarction, and biochemical parameters such as glutathione (GSH), malondialdehyde (MDA), catalase (CAT) were estimated from the brain homogenate. Further, histological studies were done to study neuronal contact. Results of molecular docking indicated that the AE exhibited interaction with active sites of cerebrotoxic proteins usually involved in protein functions or cerebrotoxicity. Biochemical results showed that in the untreated brain, MDA levels increased significantly, and decreased GSH and CAT levels were observed when compared to MO/RCA group, while treated rats showed a decrease in the levels of MDA and an increase in GSH and CAT levels as compared to MO/RCA rats. In comparison with sham rats and normal rats, histopathological analysis revealed neuronal damage in MO/RCA surgery rats which manifested as decreased intact neurons. However, treatment with AE 50 mg/kg b.wt. restored contact between neuronal cells. It can be concluded that AE showed cerebroprotective effect on RO/RCA with promising inhibition of cerebrotoxic proteins (apoptotic and neuroinflammatory) as evident from molecular docking studies. The cerebroprotective potential of AE could be due to its anti-inflammatory, antioxidant, and antiapoptotic principles.

Research Progress on Mechanism of Neuroprotective Roles of Apelin-13 in Prevention and Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common type of dementia. Currently, more than 50 million people live with dementia worldwide, and this number is expected to increase. Some of the typical pathological changes of AD include amyloid plaque, hyperphosphorylation of tau protein, secretion of inflammatory mediators, and neuronal apoptosis. Apelin is a neuroprotective peptide that is widely expressed in the body. Among members of apelin family, apelin-13 is the most abundant with a high neuroprotective function. Apelin-13/angiotensin domain type 1 receptor-associated proteins (APJ) system regulates several physiological and pathophysiological cell activities, such as apoptosis, autophagy, synaptic plasticity, and neuroinflammation. It has also been shown to prevent AD development. This article reviews the research progress on the relationship between apelin-13 and AD to provide new ideas for prevention and treatment of AD.

A New Framework to Interpret Individual Inter-Hemispheric Compensatory Communication after Stroke

Stroke constitutes the main cause of adult disability worldwide. Even after application of standard rehabilitation protocols, the majority of patients still show relevant motor impairment. Outcomes of standard rehabilitation protocols have led to mixed results, suggesting that relevant factors for brain re-organization after stroke have not been considered in explanatory models. Therefore, finding a comprehensive model to optimally define patient-dependent rehabilitation protocols represents a crucial topic in clinical neuroscience. In this context, we first report on the rehabilitation models conceived thus far in the attempt of predicting stroke rehabilitation outcomes. Then, we propose a new framework to interpret results in stroke literature in the light of the latest evidence regarding: (1) the role of the callosum in inter-hemispheric communication, (2) the role of prefrontal cortices in exerting a control function, and (3) diaschisis mechanisms. These new pieces of evidence on the role of callosum can help to understand which compensatory mechanism may take place following a stroke. Moreover, depending on the individual impairment, the prefrontal control network will play different roles according to the need of high-level motor control. We believe that our new model, which includes crucial overlooked factors, will enable clinicians to better define individualized motor rehabilitation protocols.

Calpain Inhibitors as Potential Therapeutic Modulators in Neurodegenerative Diseases

It is considered a significant challenge to understand the neuronal cell death mechanisms with a suitable cure for neurodegenerative disorders in the coming years. Calpains are one of the best-considered "cysteine proteases activated" in brain disorders. Calpain is an important marker and mediator in the pathophysiology of neurodegeneration. Calpain activation being the essential neurodegenerative factor causing apoptotic machinery activation, it is crucial to develop reliable and effective approaches to prevent calpain-mediated apoptosis in degenerating neurons. It has been recently seen that the "inhibition of calpain activation" has appeared as a possible therapeutic target for managing neurodegenerative diseases. A systematic literature review of PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was conducted. The present article reviews the basic pathobiology and role of selective calpain inhibitors used in various neurodegenerative diseases as a therapeutic target.

Dodging blood brain barrier with "nano" warriors: Novel strategy against ischemic stroke

Ischemic stroke (IS) is one of the leading causes of death and disability resulting in inevitable burden globally. Ischemic injury initiates cascade of pathological events comprising energy dwindling, failure of ionic gradients, failure of blood brain barrier (BBB), vasogenic edema, calcium over accumulation, excitotoxicity, increased oxidative stress, mitochondrial dysfunction, inflammation and eventually cell death. In spite of such complexity of the disease, the only treatment approved by US Food and Drug Administration (FDA) is tissue plasminogen activator (t-PA). This therapy overcome blood deficiency in the brain along with side effects of reperfusion which are responsible for considerable tissue injury. Therefore, there is urgent need of novel therapeutic perspectives that can protect the integrity of BBB and salvageable brain tissue. Advancement in nanomedicine is empowering new approaches that are potent to improve the understanding and treatment of the IS. Herein, we focus nanomaterial mediated drug delivery systems (DDSs) and their role to bypass and cross BBB especially via intranasal drug delivery. The various nanocarriers used in DDSs are also discussed. In a nut shell, the objective is to provide an overview of use of nanomedicine in the diagnosis and treatment of IS to facilitate the research from benchtop to bedside.

Borneol enhances the protective effect against cerebral ischemia/reperfusion injury by promoting the access of astragaloside IV and the components of Panax notoginseng saponins into the brain

BACKGROUND

Astragalus and Panax notoginseng are significant traditional Chinese medicines for treating ischemic stroke, with astragaloside IV (AST IV) and Panax notoginseng saponins (PNS) being the major effective compounds, respectively. These compounds can also be used in combination. We have previously shown that AST IV and PNS have an antagonistic effect on cerebral ischemia/reperfusion (I/R) injury, and the combination of these two drugs can elevate this effect; unfortunately, AST IV and PNS cannot easily enter the brain tissues through the blood brain barrier (BBB). Previous studies have confirmed that the combination of borneol with other agents could promote the penetration of the drug components through the BBB. However, it remains unclear whether borneol can promote entry of the active components of AST IV and PNS into the brain tissues and enhance their effect against cerebral ischemia.

OBJECTIVE

This study aimed to investigate the effects of a combination of borneol with AST IV and PNS against I/R injury and explore the mechanisms of borneol-promoting penetration of drug components into the BBB based on the drug transport of brain tissues.

METHODS

A rat model of focal cerebral I/R injury was established, and drugs, including borneol, AST IV, and PNS, as well as their combinations were intragastrically administered. Subsequently, drug efficacy was assessed, and the condition of AST IV and PNS active components (Rg1, Rb1, R1) delivered into the brain was analyzed. Moreover, BBB permeability was determined, and the expression of related drug transporters and their genes were evaluated.

RESULTS

After treatment with borneol, AST IV, PNS, AST Ⅳ+PNS, and borneol+AST Ⅳ+PNS after cerebral I/R, the neurological function deficit scores, cerebral infarct rate, and brain water content markedly decreased. The effects of the three-drug-combination were better than those of the drugs used alone and those of AST Ⅳ+PNS. Moreover, after I/R in rats, AST IV and the components of PNS (Rg1, Rb1, R1) were mainly found in the cerebral cortex and in the cerebellum, respectively, when used alone. Borneol combined with AST IV and PNS increased the contents of AST IV, Rb1, Rg1, and R1 in the cerebral cortex and in the cerebellum, thus, promoting the enrichment of active components to the cerebral cortex, especially to the affected side. In addition, following I/R, diffuse distribution of lanthanum particles in the basement membrane, intercellular and intracellular locations of rat brain tissues indicated BBB destruction and increase in permeability, which were alleviated in each drug group. The effects of borneol combined with AST IV and PNS were stronger than those of the drug single-used and those of the AST IV+PNS group. Finally, the expression of effluent transporters (ET) and their genes, including P-glycoprotein (P-gp), multidrug resistance protein (MRP)-1, MRP-2, MRP-4, and MRP-5 in brain tissues, strikingly increased after I/R. Borneol remarkedly down-regulated the protein expression of P-gp, MRP-2, and MRP-4 in the brain, whereas PNS down-regulated MRP-4 and MRP-5 protein expression. AST IV, AST IV+PNS, and bornoel+AST IV+PNS effectively decreased the expression of P-gp, MRP-2, MRP-4, and MRP-5 proteins. The effects of the three-drug combination were significantly greater than those of the drug single-used and AST IV+PNS groups. The expression of each ET gene manifested corresponding results. Meanwhile, PNS, AST IV+PNS, and bornoel+AST IV+PNS significantly inhibited the down-regulation of the uptake transporter organic anion transporting polypeptide (OATP)-2 expression, and the effect of bornoel+AST IV+PNS was stronger than that of other groups.

CONCLUSION

After I/R, the brain tissues were injured, BBB permeability increased, expression of critical ET and their genes were markedly up-regulated, and the main uptake transporters were down-regulated. We propose that the combination of borneol, AST IV and PNS could enhance the effect against cerebral I/R injury and protect BBB integrity. The potential mechanism might be the delivery of AST IV and active components of PNS to the brain tissues after treatment in combination with borneol, which could be effectively promoted by down-regulating the expression of ETs and up-regulating the expression of uptake transporters in the brain tissues. This study was the first to demonstrate that borneol combined with AST IV+PNS enhanced the effect against cerebral I/R injury through promoting the entry of AST and PNS active components to the brain tissues. Thus, this study proposes an instructive role in developing effective active ingredients combination of Chinese medicine with clear ingredients and synergistic effects in terms of the characteristic of borneol.

Oleanolic Acid Inhibits Neuronal Pyroptosis in Ischaemic Stroke by Inhibiting miR-186-5p Expression

Ischaemic stroke is a common condition leading to human disability and death. Previous studies have shown that oleanolic acid (OA) ameliorates oxidative injury and cerebral ischaemic damage, and miR-186-5p is verified to be elevated in serum from ischaemic stroke patients. Herein, we investigated whether OA regulates miR-186-5p expression to control neuroglobin (Ngb) levels, thereby inhibiting neuronal pyroptosis in ischaemic stroke. Three concentrations of OA (0.5, 2, or 8 μM) were added to primary hippocampal neurons subjected to oxygen–glucose deprivation/reperfusion (OGD/R), a cell model of ischaemic stroke. We found that OA treatment markedly inhibited pyroptosis. qRT–PCR and western blot revealed that OA suppressed the expression of pyroptosis-associated genes. Furthermore, OA inhibited LDH and proinflammatory cytokine release. In addition, miR-186-5p was downregulated while Ngb was upregulated in OA-treated OGD/R neurons. MiR-186-5p knockdown repressed OGD/R-induced pyroptosis and suppressed LDH and inflammatory cytokine release. In addition, a dual luciferase reporter assay confirmed that miR-186-5p directly targeted Ngb. OA reduced miR-186-5p to regulate Ngb levels, thereby inhibiting pyroptosis in both OGD/R-treated neurons and MCAO mice. In conclusion, OA alleviates pyroptosis in vivo and in vitro by downregulating miR-186-5p and upregulating Ngb expression, which provides a novel theoretical basis illustrating that OA can be considered a drug for ischaemic stroke.

Effects of Mdivi-1 on Neural Mitochondrial Dysfunction and Mitochondria-Mediated Apoptosis in Ischemia-Reperfusion Injury After Stroke: A Systematic Review of Preclinical Studies

This systematic review sought to determine the effects of Mitochondrial division inhibitor-1 (Mdivi-1) on neural mitochondrial dysfunction and neural mitochondria-mediated apoptosis in ischemia/reperfusion (I/R) injury after ischemic stroke. Pubmed, Web of Science, and EMBASE databases were searched through July 2021. The studies published in English language that mentioned the effects of Mdivi-1 on neural mitochondrial dysfunction and neural mitochondria-mediated apoptosis in I/R-induced brain injury were included. The CAMARADES checklist (for in vivo studies) and the TOXRTOOL checklist (for in vitro studies) were used for study quality evaluation. Twelve studies were included (median CAMARADES score = 6; TOXRTOOL scores ranging from 16 to 18). All studies investigated neural mitochondrial functions, providing that Mdivi-1 attenuated the mitochondrial membrane potential dissipation, ATP depletion, and complexes I-V abnormalities; enhanced mitochondrial biogenesis, as well as inactivated mitochondrial fission and mitophagy in I/R-induced brain injury. Ten studies analyzed neural mitochondria-mediated apoptosis, showing that Mdivi-1 decreased the levels of mitochondria-mediated proapoptotic factors (AIF, Bax, cytochrome c, caspase-9, and caspase-3) and enhanced the level of antiapoptotic factor (Bcl-2) against I/R-induced brain injury. The findings suggest that Mdivi-1 can protect neural mitochondrial functions, thereby attenuating neural mitochondria-mediated apoptosis in I/R-induced brain injury. Our review supports Mdivi-1 as a potential therapeutic compound to reduce brain damage in ischemic stroke (PROSPERO protocol registration ID: CRD42020205808). Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/], identifier [CRD42020205808].

The Protective Mechanism of Deuterated Linoleic Acid Involves the Activation of the Ca2+ Signaling System of Astrocytes in Ischemia In Vitro

Ischemia-like (oxygen-glucose deprivation, OGD) conditions followed by reoxygenation (OGD/R) cause massive death of cerebral cortex cells in culture as a result of the induction of necrosis and apoptosis. Cell death occurs as a result of an OGD-induced increase in Ca²⁺ ions in the cytosol of neurons and astrocytes, an increase in the expression of genes encoding proapoptotic and inflammatory genes with suppression of protective genes. The deuterated form of linoleic polyunsaturated fatty acid (D4-Lnn) completely inhibits necrosis and greatly reduces apoptotic cell death with an increase in the concentration of fatty acid in the medium. It was shown for the first time that D4-Lnn, through the activation of the phosphoinositide calcium system of astrocytes, causes their reactivation, which correlates with the general cytoprotective effect on the cortical neurons and astrocytes in vitro. The mechanism of the cytoprotective action of D4-Lnn involves the inhibition of the OGD-induced calcium ions, increase in the cytosolic and reactive oxygen species (ROS) overproduction, the enhancement of the expression of protective genes, and the suppression of damaging proteins.

Mitochondrial Transplantation Attenuates Cerebral Ischemia-Reperfusion Injury: Possible Involvement of Mitochondrial Component Separation

Background

Mitochondrial dysfunctions play a pivotal role in cerebral ischemia-reperfusion (I/R) injury. Although mitochondrial transplantation has been recently explored for the treatment of cerebral I/R injury, the underlying mechanisms and fate of transplanted mitochondria are still poorly understood.

Methods

Mitochondrial morphology and function were assessed by fluorescent staining, electron microscopy, JC-1, PCR, mitochondrial stress testing, and metabolomics. Therapeutic effects of mitochondria were evaluated by cell viability, reactive oxygen species (ROS), and apoptosis levels in a cellular hypoxia-reoxygenation model. Rat middle cerebral artery occlusion model was applied to assess the mitochondrial therapy in vivo. Transcriptomics was performed to explore the underlying mechanisms. Mitochondrial fate tracking was implemented by a variety of fluorescent labeling methods.

Results

Neuro-2a (N2a) cell-derived mitochondria had higher mitochondrial membrane potential, more active oxidative respiration capacity, and less mitochondrial DNA copy number. Exogenous mitochondrial transplantation increased cellular viability in an oxygen-dependent manner, decreased ROS and apoptosis levels, improved neurobehavioral deficits, and reduced infarct size. Transcriptomic data showed that the differential gene enrichment pathways are associated with metabolism, especially lipid metabolism. Mitochondrial tracking indicated specific parts of the exogenous mitochondria fused with the mitochondria of the host cell, and others were incorporated into lysosomes. This process occurred at the beginning of internalization and its efficiency is related to intercellular connection.

Conclusions

Mitochondrial transplantation may attenuate cerebral I/R injury. The mechanism may be related to mitochondrial component separation, altering cellular metabolism, reducing ROS, and apoptosis in an oxygen-dependent manner. The way of isolated mitochondrial transfer into the cell may be related to intercellular connection.

Exosomes derived from mesenchyml stem cells ameliorate oxygen-glucose deprivation/reoxygenation-induced neuronal injury via transferring MicroRNA-194 and targeting Bach1

The neuroprotective function of miR-194 on neurovascular endothelial cell injury is perceived as a novel method for clinical therapy. So are exosomes (EXs), being attractive in neurofunctional recovery. However, whether EXs derived from mesenchymal stromal cells (MSCs) perform the same efficacy by transferring miR-194 and the underlying mechanism remain vague. This study rooted in oxygen-glucose deprivation/reoxygenation (OGD/R) model. MSCs were isolated by gradient centrifugation and identified by flow cytometry. EXs were obtained through ultracentrifugation, whereas protein levels of specific markers (CD63, TGS101), together with Bach1, Nrf2 and HO-1 were measured by western blot. The relative mRNA expressions of Bach1, NOX1, AGSL4, GPX4 and miR-194 were measured by RT-qPCR assays. Cell viability was measured by cell counting kit-8, and cell migration was detected by wound healing assay. The interaction between miR-194 and Bach1 was predicted by starBase and confirmed by dual luciferase reporter assay. OGD/R dampened cell viability and miR-194 expression. Bach1 could bind with miR-194. miR-194 mimic attenuated the effect of OGD/R on cell viability and protein levels of Nrf2, HO-1 and Bach1, whereas Bach1 overexpression reversed the effect of miR-194 mimics. MSC-EXs could merge with HBMECs. Based on this, MSC-EXs loaded with miR-194 downregulated Bach1 protein level and iron content and the mRNA expressions of NOX1 and ACSL4, yet upregulated miR-194 and GPX4 expressions and Nrf2/HO-1 protein level in OGD/R-injured cells, whereas those carrying ShmiR-194 had the opposite effects. Our study suggested MSC-EXs loaded with miR-194 attenuated OGD/R-induced injury via targeting Bach1, providing a new therapeutic strategy for cerebral injuries.

Nuclear receptor coactivator 4-mediated ferritinophagy contributes to cerebral ischemia-induced ferroptosis in ischemic stroke

Ischemic stroke poses a significant health risk due to its high rate of disability and mortality. To address this problem, several therapeutic approaches have been proposed, including interruption targeting programmed cell death (PCD). Ferroptosis is a newly defined PCD characterized by iron-dependent accumulation of lipid peroxidation, and is becoming a promising target for treating numerous diseases. To explore the underlying mechanisms of the initiation and execution of ferroptosis in ischemic stroke, we established stroke models in vivo and in vitro simulating ischemia/reperfusion (I/R) neuronal injury. Different from previous reports on stroke, we tested ferroptosis by measuring the levels of core proteins, such as ACSL4, 15-LOX2, Ferritin and GPX4. In addition, I/R injury induces excessive degradation of ferritin via the autophagy pathway and subsequent increase of free iron in neurons. This phenomenon has recently been termed ferritinophagy and reported to be regulated by nuclear receptor coactivator 4 (NCOA4) in some cell lines. Increased NCOA4 in cytoplasm was detected in our study and then silenced by shRNA to investigate its function. Both in vivo and in vitro, NCOA4 deletion notably abrogated ferritinophagy caused by I/R injury and thus inhibited ferroptosis. Furthermore, we found that NCOA4 was upregulated by ubiquitin specific peptidase 14 (USP14) via a deubiquitination process in damaged neurons, and we found evidence of pharmacological inhibition of USP14 effectively reducing NCOA4 levels to protect neurons from ferritinophagy-mediated ferroptosis. These findings suggest a novel and effective target for treating ischemic stroke.

Carbonic Anhydrases as Potential Targets Against Neurovascular Unit Dysfunction in Alzheimer’s Disease and Stroke

The Neurovascular Unit (NVU) is an important multicellular structure of the central nervous system (CNS), which participates in the regulation of cerebral blood flow (CBF), delivery of oxygen and nutrients, immunological surveillance, clearance, barrier functions, and CNS homeostasis. Stroke and Alzheimer Disease (AD) are two pathologies with extensive NVU dysfunction. The cell types of the NVU change in both structure and function following an ischemic insult and during the development of AD pathology. Stroke and AD share common risk factors such as cardiovascular disease, and also share similarities at a molecular level. In both diseases, disruption of metabolic support, mitochondrial dysfunction, increase in oxidative stress, release of inflammatory signaling molecules, and blood brain barrier disruption result in NVU dysfunction, leading to cell death and neurodegeneration. Improved therapeutic strategies for both AD and stroke are needed. Carbonic anhydrases (CAs) are well-known targets for other diseases and are being recently investigated for their function in the development of cerebrovascular pathology. CAs catalyze the hydration of CO₂ to produce bicarbonate and a proton. This reaction is important for pH homeostasis, overturn of cerebrospinal fluid, regulation of CBF, and other physiological functions. Humans express 15 CA isoforms with different distribution patterns. Recent studies provide evidence that CA inhibition is protective to NVU cells in vitro and in vivo, in models of stroke and AD pathology. CA inhibitors are FDA-approved for treatment of glaucoma, high-altitude sickness, and other indications. Most FDA-approved CA inhibitors are pan-CA inhibitors; however, specific CA isoforms are likely to modulate the NVU function. This review will summarize the literature regarding the use of pan-CA and specific CA inhibitors along with genetic manipulation of specific CA isoforms in stroke and AD models, to bring light into the functions of CAs in the NVU. Although pan-CA inhibitors are protective and safe, we hypothesize that targeting specific CA isoforms will increase the efficacy of CA inhibition and reduce side effects. More studies to further determine specific CA isoforms functions and changes in disease states are essential to the development of novel therapies for cerebrovascular pathology, occurring in both stroke and AD.

Nuclear Receptors in Myocardial and Cerebral Ischemia-Mechanisms of Action and Therapeutic Strategies

Nearly 18 million people died from cardiovascular diseases in 2019, of these 85% were due to heart attack and stroke. The available therapies although efficacious, have narrow therapeutic window and long list of contraindications. Therefore, there is still an urgent need to find novel molecular targets that could protect the brain and heart against ischemia without evoking major side effects. Nuclear receptors are one of the promising targets for anti-ischemic drugs. Modulation of estrogen receptors (ERs) and peroxisome proliferator-activated receptors (PPARs) by their ligands is known to exert neuro-, and cardioprotective effects through anti-apoptotic, anti-inflammatory or anti-oxidant action. Recently, it has been shown that the expression of aryl hydrocarbon receptor (AhR) is strongly increased after brain or heart ischemia and evokes an activation of apoptosis or inflammation in injury site. We hypothesize that activation of ERs and PPARs and inhibition of AhR signaling pathways could be a promising strategy to protect the heart and the brain against ischemia. In this Review, we will discuss currently available knowledge on the mechanisms of action of ERs, PPARs and AhR in experimental models of stroke and myocardial infarction and future perspectives to use them as novel targets in cardiovascular diseases.

Hypoxia-preconditioned mesenchymal stem cells attenuate microglial pyroptosis after intracerebral hemorrhage

Background

Microglia plays a vital role in neuroinflammation, contributing to the pathogenesis of intracerebral hemorrhage (ICH)-induced brain injury. Mesenchymal stem cells (MSCs) hold great potential for treating ICH. We previously revealed that MSCs ameliorate the microglial pyroptosis caused by an ischemic stroke. However, whether MSCs can modulate microglial pyroptosis after ICH remains unknown. This study aimed to investigate the neuroprotective effects of hypoxia-preconditioned olfactory mucosa MSCs (OM-MSCs) on ICH and the possible mechanisms.

Methods

ICH was induced in mice via administration of collagenase IV. At 6 h post-ICH, 2-4×10⁵ normoxic/hypoxic OM-MSCs or saline were intracerebrally administered. To evaluate the neuroprotective effects, the behavioral outcome, apoptosis, and neuronal injury were measured. Microglia activation and pro-inflammatory cytokines were applied to detect neuroinflammation. Microglial pyroptosis was determined by western blotting, immunofluorescence staining, and transmission electron microscopy (TEM).

Results

The two OM-MSC-transplanted groups exhibited significantly improved functional recovery and reduced neuronal injury, especially the hypoxic OM-MSCs group. Hypoxic OM-MSCs attenuated microglial activation as well as the levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Moreover, we found that hypoxia-preconditioned OM-MSCs ameliorated pyroptosis by diminishing the levels of pyroptosis-associated proteins in peri-hematoma brain tissues, decreasing the expression of the microglial nod-like receptor family protein 3 (NLRP3) and caspase-1, and reducing the membrane pores on microglia post-ICH.

Conclusions

Our study showed that hypoxic preconditioning augments the therapeutic efficacy of OM-MSCs, and hypoxia-preconditioned OM-MSCs alleviate microglial pyroptosis in the ICH model.

Association of Proinflammatory Cytokine Levels with Stroke Severity, Infarct Size, and Muscle Strength in the Acute Phase of Stroke

OBJECTIVE

Patterns of cytokine levels and their association with stroke severity, infarct size, and muscle strength are obscure. We aimed to analyze the immune mediators linked to T helper (Th)1, Th2, Th17, and regulatory T cell patterns and their association with stroke severity, infarct size, and muscle strength.

MATERIALS AND METHODS

We included patients with acute stroke (n = 15) and healthy non-disabled individuals (n = 20) aged > 18 years. The dependent variables were stroke severity according to the National Institute of Health Stroke Scale (NIHSS), infarct size on computed tomography, handgrip strength by dynamometry, and global muscle strength according to the Medical Research Council (MRC) scale. The independent variables were the circulating cytokine levels. The cytokine levels were compared between the groups, and correlations between the clinical data were verified.

RESULTS

The stroke group had higher interleukin (IL)-6 (p < 0.0001) and IL-10 (p < 0.0001) levels, but lower tumor necrosis factor (TNF)-α (p = 0.036) levels than the control group. IL-10 and soluble tumor necrosis factor receptor (sTNF-RII) levels were correlated with each other (r = 0.533; p = 0.042) and infarct size (r = 0.653; p = 0.033 and r = 0.689; p = 0.018, respectively). MRC scores were positively and negatively correlated with handgrip strength of the affected side (r = 0.78; p = 0.001) and NIHSS scores (r = -0.87; p < 0.0001), respectively.

CONCLUSIONS

Plasma levels of some cytokines were associated with changes in the acute phase of stroke, and IL-10 and sTNF-RII levels are potential biomarkers of infarct size.

Enriched Environment Attenuates Pyroptosis to Improve Functional Recovery After Cerebral Ischemia/Reperfusion Injury

Enriched environment (EE) is a complex containing social, cognitive, and motor stimuli. Exposure to EE can promote functional recovery after ischemia/reperfusion (I/R) injury. However, the underlying mechanisms remained unclear. Pyroptosis has recently been identified and demonstrated a significant role in ischemic stroke. The purpose of this study was to explore the effect of EE on neuronal pyroptosis after cerebral I/R injury. In the current study, middle cerebral artery occlusion/reperfusion (MCAO/R) was applied to establish the cerebral I/R injury model. Behavior tests including the modified Neurological Severity Scores (mNSS) and the Morris Water Maze (MWM) were performed. The infarct volume was evaluated by Nissl staining. To evaluate the levels of pyroptosis-related proteins, the levels of GSDMD-N and nod-like receptor protein 1/3 (NLRP1/3) inflammasome-related proteins were examined. The mRNA levels of IL-1β and IL-18 were detected by Quantitative Real-Time PCR (qPCR). The secretion levels of IL-1β and IL-18 were analyzed by ELISA. Also, the expression of p65 and p-p65 were detected. The results showed that EE treatment improved functional recovery, reduced infarct volume, attenuated neuronal pyroptosis after cerebral I/R injury. EE treatment also suppressed the activities of NLRP1/NLRP3 inflammasomes. These may be affected by inhabiting the NF-κB p65 signaling pathway. Our findings suggested that neuronal pyroptosis was probably the neuroprotective mechanism that EE treatment rescued neurological deficits after I/R injury.

Sildenafil-Mediated Neuroprotection from Adult to Neonatal Brain Injury: Evidence, Mechanisms, and Future Translation

Cerebral stroke, traumatic brain injury, and hypoxic ischemic encephalopathy are among the most frequently occurring brain injuries. A complex pathogenesis, characterized by a synergistic interaction between alterations of the cerebrovascular system, cell death, and inflammation, is at the basis of the brain damage that leads to behavioral and neurodevelopmental disabilities in affected subjects. Sildenafil is a selective inhibitor of the enzyme phosphodiesterase 5 (PDE5) that is able to cross the blood-brain barrier. Preclinical data suggest that sildenafil may be a good candidate for the prevention or repair of brain injury in both adults and neonates. The aim of this review is to summarize the evidence supporting the neuroprotective action of sildenafil and discuss the possible benefits of the association of sildenafil with current therapeutic strategies.

Therapeutic Potential and Main Methods of Obtaining Selenium Nanoparticles

This review presents the latest data on the importance of selenium nanoparticles in human health, their use in medicine, and the main known methods of their production by various methods. In recent years, a multifaceted study of nanoscale complexes in medicine, including selenium nanoparticles, has become very important in view of a number of positive features that make it possible to create new drugs based on them or significantly improve the properties of existing drugs. It is known that selenium is an essential trace element that is part of key antioxidant enzymes. In mammals, there are 25 selenoproteins, in which selenium is a key component of the active site. The important role of selenium in human health has been repeatedly proven by several hundred works in the past few decades; in recent years, the study of selenium nanocomplexes has become the focus of researchers. A large amount of accumulated data requires generalization and systematization in order to improve understanding of the key mechanisms and prospects for the use of selenium nanoparticles in medicine, which is the purpose of this review.

Emerging immune and cell death mechanisms in stroke: Saponins as therapeutic candidates

The complexity of the ischemic cascade is based on the integrated crosstalk of every cell type in the neurovascular unit. Depending on the features of the ischemic insult, several cell death mechanisms are triggered, such as apoptosis, necroptosis, ferroptosis/oxytosis, ETosis or pyroptosis, leading to reactive astrogliosis. However, emerging evidence demonstrates a dual role for the immune system in stroke pathophysiology, where it exerts both detrimental and also beneficial functions. In this review, we discuss the relevance of several cell death modalities and the dual role of the immune system in stroke pathophysiology. We also provide an overview of some emerging immunomodulatory therapeutic strategies, amongst which saponins, which are promising candidates that exert multiple pharmacological effects.

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Several cell death mechanisms coexist in stroke pathophysiology.

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Neurons are more vulnerable to necroptosis than glial cells.

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Inhibitors of receptor-interacting protein kinases and of ferroptosis induce neuroprotection.

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Saponins exert modulatory effects on inflammation and neuronal cell death in stroke.

Endothelial Thioredoxin-Interacting Protein Depletion Reduces Hemorrhagic Transformation in Hyperglycemic Mice after Embolic Stroke and Thrombolytic Therapy

We hypothesize that endothelial-specific thioredoxin-interacting protein knock-out (EC-TXNIP KO) mice will be more resistant to the neurovascular damage (hemorrhagic-transformation-HT) associated with hyperglycemia (HG) in embolic stroke. Adult-male EC-TXNIP KO and wild-type (WT) littermate mice were injected with-streptozotocin (40 mg/kg, i.p.) for five consecutive days to induce diabetes. Four-weeks after confirming HG, mice were subjected to embolic middle cerebral artery occlusion (eMCAO) followed by tissue plasminogen activator (tPA)-reperfusion (10 mg/kg at 3 h post-eMCAO). After the neurological assessment, animals were sacrificed at 24 h for neurovascular stroke outcomes. There were no differences in cerebrovascular anatomy between the strains. Infarct size, edema, and HT as indicated by hemoglobin (Hb)-the content was significantly higher in HG-WT mice, with or without tPA-reperfusion, compared to normoglycemic WT mice. Hyperglycemic EC-TXNIP KO mice treated with tPA tended to show lower Hb-content, edema, infarct area, and less hemorrhagic score compared to WT hyperglycemic mice. EC-TXNIP KO mice showed decreased expression of inflammatory mediators, apoptosis-associated proteins, and nitrotyrosine levels. Further, vascular endothelial growth factor-A and matrix-metalloproteinases (MMP-9/MMP-3), which degrade junction proteins and increase blood-brain-barrier permeability, were decreased in EC-TXNIP KO mice. Together, these findings suggest that vascular-TXNIP could be a novel therapeutic target for neurovascular damage after stroke.

Mitochondrial Dynamics: A Potential Therapeutic Target for Ischemic Stroke

Stroke is one of the leading causes of death and disability worldwide. Brain injury after ischemic stroke involves multiple pathophysiological mechanisms, such as oxidative stress, mitochondrial dysfunction, excitotoxicity, calcium overload, neuroinflammation, neuronal apoptosis, and blood-brain barrier (BBB) disruption. All of these factors are associated with dysfunctional energy metabolism after stroke. Mitochondria are organelles that provide adenosine triphosphate (ATP) to the cell through oxidative phosphorylation. Mitochondrial dynamics means that the mitochondria are constantly changing and that they maintain the normal physiological functions of the cell through continuous division and fusion. Mitochondrial dynamics are closely associated with various pathophysiological mechanisms of post-stroke brain injury. In this review, we will discuss the role of the molecular mechanisms of mitochondrial dynamics in energy metabolism after ischemic stroke, as well as new strategies to restore energy homeostasis and neural function. Through this, we hope to uncover new therapeutic targets for the treatment of ischemic stroke.

Dengzhanxixin Injection Ameliorates Cognitive Impairment Through a Neuroprotective Mechanism Based on Mitochondrial Preservation in Patients With Acute Ischemic Stroke

Acute ischemic stroke (AIS) is a global health burden and cognitive impairment is one of its most serious complication. Adequate interventions for AIS may have the potential to improve cognitive outcomes. In the present study, we selected Erigeron breviscapus (Vaniot) Hand.-Mazz. injection (Dengzhanxixin injection, DZXI), a widely used Chinese herbal injection, in contrast to edaravone as the positive control drug to test its potential to ameliorates neurological and cognitive impairments caused by AIS. We performed a 2-week randomized trial with these two drugs in AIS patients presenting mild to moderate cognitive impairments. Neuropsychological tests and MRI examinations showed that DZXI attenuated the neurological and cognitive impairments of patients and protected the grey matter in specific regions from ischemic damage. Notably, DZXI exerted better effects than edaravone in some neuropsychological tests, probably due to the protective effect of DZXI on grey matter. To explore the therapeutic mechanisms, we carried out an experiment with a middle cerebral artery occlusion rat model. We found that DZXI decreased the infarct volume and increased the survival of neuronal cells in the ischemic penumbra; furthermore, DZXI modulated the mitochondrial respiratory chain process and preserved the mitochondrial structure in the brain tissue. Overall, our data suggested that the administration of DZXI is effective at ameliorating neurological and cognitive impairments in AIS, and the underlying mechanisms are related to the protective effects of DZXI on cerebral neurons and neuronal mitochondria.

TGFβ-Neurotrophin Interactions in Heart, Retina, and Brain

Ischemic insults to the heart and brain, i.e., myocardial and cerebral infarction, respectively, are amongst the leading causes of death worldwide. While there are therapeutic options to allow reperfusion of ischemic myocardial and brain tissue by reopening obstructed vessels, mitigating primary tissue damage, post-infarction inflammation and tissue remodeling can lead to secondary tissue damage. Similarly, ischemia in retinal tissue is the driving force in the progression of neovascular eye diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD), which eventually lead to functional blindness, if left untreated. Intriguingly, the easily observable retinal blood vessels can be used as a window to the heart and brain to allow judgement of microvascular damages in diseases such as diabetes or hypertension. The complex neuronal and endocrine interactions between heart, retina and brain have also been appreciated in myocardial infarction, ischemic stroke, and retinal diseases. To describe the intimate relationship between the individual tissues, we use the terms heart-brain and brain-retina axis in this review and focus on the role of transforming growth factor β (TGFβ) and neurotrophins in regulation of these axes under physiologic and pathologic conditions. Moreover, we particularly discuss their roles in inflammation and repair following ischemic/neovascular insults. As there is evidence that TGFβ signaling has the potential to regulate expression of neurotrophins, it is tempting to speculate, and is discussed here, that cross-talk between TGFβ and neurotrophin signaling protects cells from harmful and/or damaging events in the heart, retina, and brain.

Transient Oxygen-Glucose Deprivation Causes Region- and Cell Type-Dependent Functional Deficits in the Mouse Hippocampus In Vitro

Neurons are highly vulnerable to conditions of hypoxia-ischemia (HI) such as stroke or transient ischemic attacks. Recovery of cognitive and behavioral functions requires re-emergence of coordinated network activity, which, in turn, relies on the well-orchestrated interaction of pyramidal cells (PYRs) and interneurons. We therefore modelled HI in the mouse hippocampus, a particularly vulnerable region showing marked loss of PYR and fast-spiking interneurons (FSIs) after hypoxic-ischemic insults. Transient oxygen-glucose deprivation (OGD) in ex vivo hippocampal slices led to a rapid loss of neuronal activity and spontaneous network oscillations (sharp wave-ripple complexes; SPW-Rs), and to the occurrence of a spreading depolarization. Following reperfusion, both SPW-R and neuronal spiking resumed, but FSI activity remained strongly reduced compared with PYR. Whole-cell recordings in CA1 PYR revealed, however, a similar reduction of both EPSCs and IPSCs, leaving inhibition-excitation (I/E) balance unaltered. At the network level, SPW-R incidence was strongly reduced and the remaining network events showed region-specific changes including reduced ripple energy in CA3 and increased ripple frequency in CA1. Together, our data show that transient hippocampal energy depletion results in severe functional alterations at the cellular and network level. While I/E balance is maintained, synaptic activity, interneuron spiking and coordinated network patterns remain reduced. Such alterations may be network-level correlates of cognitive and functional deficits after cerebral HI.

Uncovering the mechanism of the Shenzhi Jiannao formula against vascular dementia using a combined network pharmacology approach and molecular biology

BACKGROUND

Shenzhi Jiannao formula (SZJNF) is a herbal prescription which is used for detoxification, dredging collaterals, and activating blood circulation and Qi flow in traditional Chinese medicine. SZJNF is a clinical effective prescription for the treatment of vascular dementia (VD) first formulated based on the classical theory of traditional Chinese medicine, but its anti-VD mechanism remains ambiguous.

PURPOSE

The aim of this study was to elucidate the multi-target mechanisms of SZJNF against VD using a network pharmacology approach and verify its effects through biological experiments.

STUDY DESIGN AND METHODS

We utilized network pharmacology-based prediction and molecular docking techniques to uncover the potential micro-mechanism of SZJNF against VD. We identified active components and potential targets, and performed network analysis, functional annotation, and pathway enrichment analysis. Subsequently, glutamate-induced PC12 cells and VD rats were used to verify the molecular mechanisms of SZJNF.

RESULTS

Seventeen active compounds were identified in SZJNF rat plasma; moreover, 773 predicted targets and 1544 VD-related targets were found. Various networks, including the PPI, herb-compound-target, and compound-target-pathway network were constructed. A total of 188 shared targets were identified by network topological analysis, which were closely associated to the anti-VD effects of SZJNF. They were also enriched in various biological processes through hypoxia reaction, promotion of cell proliferation, inhibition of apoptosis, neuroactive ligand-receptor interaction, and calcium signaling pathway, as evaluated by the analysis of advanced functions and pathways. SZJNF components docked well with the key targets. Treatment with SZJNF promoted cell proliferation, ameliorated apoptosis and oxidative stress injury, and improved neurological and cognitive abilities.

CONCLUSION

This study comprehensively demonstrated the multi-target mechanisms of SZJNF in VD using network pharmacology and molecular biology experiments. This provides evidence for further mechanistic studies and for the development of SZJNF as a potential treatment for patients with VD.

Autophagy Elicits Neuroprotection at the Subacute Phase of Transient Cerebral Ischaemia but Has Few Effects on Neurological Outcomes After Permanent Ischaemic Stroke in Rats

OBJECTIVE

Autophagy was prominently activated by cerebral ischaemia. This study was to investigate the exact role of autophagy in ischaemic stroke.

METHODS

Two rat models of transient middle cerebral artery occlusion (tMCAO) and permanent MCAO (pMCAO) were prepared. The brain tissues in the penumbra were obtained to observe the dynamic variations of autophagy activity with Beclin1 and LC3 antibodies by Western blotting. At the characteristic time points, when autophagy activity was markedly elevated or reduced, the autophagy activation signaling was intervened with rapamycin and 3-methyladenine, respectively. Thereafter, key proteins in the autopahgic/lysosomal pathway were detected with the antibodies of LC3, p62, ubiquitin, LAMP-1 and cathepsin B. Meanwhile, TTC staining, neurological score and immunofluorescence were performed to evaluate brain infarct volume, neurological deficit and neuron survival, respectively.

RESULTS

Both Beclin1 and LC3 expression levels were remarkably altered at 6 h, 12 h, 2 days and 7 days after tMCAO. Interestingly, the dynamic changes of autophagy activity following pMCAO were identical to those after tMCAO. Neither autophagy induction nor autophagy inhibition was able to ameliorate the pMCAO-induced neurological injury due to lysosomal dysfunction, as indicated by low levels of LAMP-1 and cathepsin B, accompanied with the accumulation of LC3-II, ubiquitin and insoluble p62. Comparatively, autophagy induction elicited overt neuroprotection at 2 and 7 days after tMCAO, and this neuroprotection might be elicited by the enhancement of autophagy flux.

CONCLUSION

Our study suggests that autophagy confers neuroprotection at the subacute phase of tMCAO but has few effects on neurological outcomes after pMCAO.

HDAC1 deregulation promotes neuronal loss and deficit of motor function in stroke pathogenesis

Stroke is a common cause of death worldwide and leads to disability and cognitive dysfunction. Ischemic stroke and hemorrhagic stroke are major categories of stroke, accounting for 68% and 32% of strokes, respectively. Each year, 15 million people experience stroke worldwide, and the stroke incidence is rising. Epigenetic modifications regulate gene transcription and play a major role in stroke. Accordingly, histone deacetylase 1 (HDAC1) participates in DNA damage repair and cell survival. However, the mechanisms underlying the role of HDAC1 in stroke pathogenesis are still controversial. Therefore, we investigated the role of HDAC1 in stroke by using a rat model of endothelin-1-induced brain ischemia. Our results revealed that HDAC1 was deregulated following stroke, and its expressional level and enzymatic activity were decreased. We also used MS-275 to inhibit HDAC1 function in rats exposed to ischemic insult. We found that HDAC1 inhibition promoted the infarct volume, neuronal loss, DNA damage, neuronal apoptosis after stroke, and levels of reactive oxygen species and inflammation cytokines. Additionally, HDAC1 inhibition deteriorated the behavioral outcomes of rats with ischemic insult. Overall, our findings demonstrate that HDAC1 participates in ischemic pathogenesis in the brain and possesses potential for use as a therapeutic target.