Baicalin Attenuates Blood-Brain Barrier Disruption and Hemorrhagic Transformation and Improves Neurological Outcome in Ischemic Stroke Rats with Delayed t-PA Treatment: Involvement of ONOO--MMP-9 Pathway

Ethanolic extract of Arctium lappa leaves alleviates cerebral ischemia reperfusion-induced inflammatory injury via HDAC9-mediated NF-κB pathway

BACKGROUND

Ischemic stroke (IS) is a major cause of mortality and disability worldwide. Inflammatory response is crucial in the pathogenesis of tissue injury in cerebral infarction. Arctium lappa leaves are traditionally used to treat IS.

PURPOSES

To investigate the neuroprotective effects and molecular mechanisms of the ethanolic extract of A. lappa leaves (ALLEE) on cerebral ischemia-reperfusion (CIR).

METHODS

Middle cerebral artery obstruction reperfusion (MCAO/R) rats and an oxygen-glucose deprivation/reoxygenation (OGD/R) cell model were used to evaluate ALLEE pharmacodynamics. Various methods, including neurological function, 2,3,5-triphenyltetrazolium chloride, hematoxylin and eosin, and Nissl, enzyme-linked immunosorbent, and TdT-mediated dUTP nick-end labeling assays, were used to analyze the neuroprotective effects of ALLEE in vitro and in vivo. The major chemical components and potential target genes of ALLEE were screened using network pharmacology. Molecular docking, western blotting, and immunofluorescence analyses were performed to confirm the effectiveness of the targets in related pathways.

RESULTS

ALLEE exerted potent effects on the MCAO/R model by decreasing the neurological scores, infarct volumes, and pathological features (p < 0.01). Furthermore, network pharmacology results revealed that the treatment of IS with ALLEE involved the regulation of various inflammatory pathways, such as the tumor necrosis factor (TNF) and chemokine signaling pathways. ALLEE also played key roles in targeting key molecules, including nuclear factor (NF)-κBIA, NF-κB1, interleukin (IL)-6, TNF-α and IL1β, and regulating the histone deacetylase (HDAC)-9-mediated signaling pathway. In vivo and in vitro analyses revealed that ALLEE significantly regulated the NF-κB pathway, promoted the phosphorylation activation of NF-κB P65, IκB and IKK (p < 0.01 or p < 0.05), and decreased the expression levels of the inflammatory factors, IL-1β, IL-6 and TNF-α (p < 0.01). Moreover, ALLEE significantly decreased the expression of HDAC9 (p < 0.01) that is associated with inflammatory responses. However, HDAC9 overexpression partially reversed the neuroprotective effects of ALLEE and its suppressive effects on inflammation and phosphorylation of NF-κB (p < 0.01).

CONCLUSIONS

In conclusion, our results revealed that ALLEE ameliorates MCAO/R-induced experimental CIR by modulating inflammatory responses via the inhibition of HDAC9-mediated NF-κB pathway.

Peroxynitrite-Triggered Carbon Monoxide Donor Improves Ischemic Stroke Outcome by Inhibiting Neuronal Apoptosis and Ferroptosis

Cerebral ischemia-reperfusion injury produces excessive reactive oxygen and nitrogen species, including superoxide, nitric oxide, and peroxynitrite (ONOO-). We recently developed a new ONOO--triggered metal-free carbon monoxide donor (PCOD585), exhibiting a notable neuroprotective outcome on the rat middle cerebral artery occlusion model and rendering an exciting intervention opportunity toward ischemia-induced brain injuries. However, its therapeutic mechanism still needs to be addressed. In the pharmacological study, we found PCOD585 inhibited neuronal Bcl2/Bax/caspase-3 apoptosis pathway in the peri-infarcted area of stroke by scavenging ONOO-. ONOO- scavenging further led to decreased Acyl-CoA synthetase long-chain family member 4 and increased glutathione peroxidase 4, to minimize lipoperoxidation. Additionally, the carbon monoxide release upon the ONOO- reaction with PCOD585 further inhibited the neuronal Iron-dependent ferroptosis associated with ischemia-reperfusion. Such a synergistic neuroprotective mechanism of PCOD585 yields as potent a neuroprotective effect as Edaravone. Additionally, PCOD585 penetrates the blood-brain barrier and reduces the degradation of zonula occludens-1 by inhibiting matrix metalloproteinase-9, thereby protecting the integrity of the blood-brain barrier. Our study provides a new perspective for developing multi-functional compounds to treat ischemic stroke.

Drugs/agents for the treatment of ischemic stroke: Advances and perspectives

Ischemic stroke (IS) poses a significant threat to global human health and life. In recent decades, we have witnessed unprecedented progresses against IS, including thrombolysis, thrombectomy, and a few medicines that can assist in reopening the blocked brain vessels or serve as standalone treatments for patients who are not eligible for thrombolysis/thrombectomy therapies. However, the narrow time windows of thrombolysis/thrombectomy, coupled with the risk of hemorrhagic transformation, as well as the lack of highly effective and safe medications, continue to present big challenges in the acute treatment and long-term recovery of IS. In the past 3 years, several excellent articles have reviewed pathophysiology of IS and therapeutic medicines for the treatment of IS based on the pathophysiology. Regretfully, there is no comprehensive overview to summarize all categories of anti-IS drugs/agents designed and synthesized based on molecular mechanisms of IS pathophysiology. From medicinal chemistry view of point, this article reviews a multitude of anti-IS drugs/agents, including small molecule compounds, natural products, peptides, and others, which have been developed based on the molecular mechanism of IS pathophysiology, such as excitotoxicity, oxidative/nitrosative stresses, cell death pathways, and neuroinflammation, and so forth. In addition, several emerging medicines and strategies, including nanomedicines, stem cell therapy and noncoding RNAs, which recently appeared for the treatment of IS, are shortly introduced. Finally, the perspectives on the associated challenges and future directions of anti-IS drugs/agents are briefly provided to move the field forward.

Qingda granule alleviates cerebral ischemia/reperfusion injury by inhibiting TLR4/NF-κB/NLRP3 signaling in microglia

ETHNOPHARMACOLOGICAL RELEVANCE

Qingda granule (QDG) is effective for treating hypertension and neuronal damage after cerebral ischemia/reperfusion. However, the anti-neuroinflammatory effect of QDG on injury due to cerebral ischemia/reperfusion is unclear.

AIM OF THE STUDY

The objective was to evaluate the effectiveness and action of QDG in treating neuroinflammation resulting from cerebral ischemia/reperfusion-induced injury.

MATERIALS AND METHODS

Network pharmacology was used to predict targets and pathways of QDG. An in vivo rat model of middle cerebral artery occlusion/reperfusion (MCAO/R) as well as an in vitro model of LPS-stimulated BV-2 cells were established. Magnetic resonance imaging (MRI) was used to quantify the area of cerebral infarction, with morphological changes in the brain being assessed by histology. Immunohistochemistry (IHC) was used to assess levels of the microglial marker IBA-1 in brain tissue. Bioplex analysis was used to measure TNF-α, IL-1β, IL-6, and MCP-1 in sera and in BV-2 cell culture supernatants. Simultaneously, mRNA levels of these factors were examined using RT-qPCR analysis. Proteins of the TLR4/NF-κB/NLRP3 axis were examined using IHC in vivo and Western blot in vitro, respectively. While NF-κB translocation was assessed using immunofluorescence.

RESULTS

The core targets of QDG included TNF, NF-κB1, MAPK1, MAPK3, JUN, and TLR4. QDG suppressed inflammation via modulation of TLR4/NF-κB signaling. In addition, our in vivo experiments using MCAO/R rats demonstrated the therapeutic effect of QDG in reducing brain tissue infarction, improving neurological function, and ameliorating cerebral histopathological damage. Furthermore, QDG reduced the levels of TNF-α, IL-1β, IL-6, and MCP-1 in both sera from MCAO/R rats and supernatants from LPS-induced BV-2 cells, along with a reduction in the expression of the microglia biomarker IBA-1, as well as that of TLR4, MyD88, p-IKK, p-IκBα, p-P65, and NLRP3 in MCAO/R rats. In LPS-treated BV-2 cells, QDG downregulated the expression of proinflammatory factors and TLR4/NF-κB/NLRP3 signaling-related proteins. Additionally, QDG reduced translocation of NF-κB to the nucleus in both brains of MCAO/R rats and LPS-induced BV-2 cells. Moreover, the combined treatment of the TLR4 inhibitor TAK242 and QDG significantly reduced the levels of p-P65, NLRP3, and IL-6.

CONCLUSIONS

QDG significantly suppressed neuroinflammation by inhibiting the TLR4/NF-κB/NLRP3 axis in microglia. This suggests potential for QDG in treating ischemia stroke.

FDA compound library screening Baicalin upregulates TREM2 for the treatment of cerebral ischemia-reperfusion injury

Acute ischemic stroke (AIS) is a leading cause of global incidence and mortality rates. Oxidative stress and inflammation are key factors in the pathogenesis of AIS neuroinjury. Therefore, it is necessary to develop drugs that target neuroinflammation and oxidative stress in AIS. The Triggering Receptor Expressed on Myeloid Cells 2 (TREM2), primarily expressed on microglial cell membranes, plays a critical role in reducing inflammation and oxidative stress in AIS. In this study, we employed a high-throughput screening (HTS) strategy to evaluate 2625 compounds from the (Food and Drug Administration) FDA library in vitro to identify compounds that upregulate the TREM2 receptor on microglia. Through this screening, we identified Baicalin as a potential drug for AIS treatment. Baicalin, a flavonoid compound extracted and isolated from the root of Scutellaria baicalensis, demonstrated promising results. Next, we established an in vivo mouse model of cerebral ischemia-reperfusion injury (MCAO/R) and an in vitro microglia cell of oxygen-glucose deprivation reperfusion (OGD/R) to investigate the role of Baicalin in inflammation injury, oxidative stress, and neuronal apoptosis. Our results showed that baicalin effectively inhibited microglia activation, reactive oxygen species (ROS) production, and inflammatory responses in vitro. Additionally, baicalin suppressed neuronal cell apoptosis. In the in vivo experiments, baicalin not only improved neurological functional deficits and reduced infarct volume but also inhibited microglia activation and inflammatory responses. Overall, our findings demonstrate the efficacy of Baicalin in treating MCAO/R by upregulating TREM2 to reduce inflammatory responses and inhibit neuronal apoptosis.

Hypochlorous acid derived from microglial myeloperoxidase could mediate high-mobility group box 1 release from neurons to amplify brain damage in cerebral ischemia-reperfusion injury

Myeloperoxidase (MPO) plays critical role in the pathology of cerebral ischemia-reperfusion (I/R) injury via producing hypochlorous acid (HOCl) and inducing oxidative modification of proteins. High-mobility group box 1 (HMGB1) oxidation, particularly disulfide HMGB1 formation, facilitates the secretion and release of HMGB1 and activates neuroinflammation, aggravating cerebral I/R injury. However, the cellular sources of MPO/HOCl in ischemic brain injury are unclear yet. Whether HOCl could promote HMGB1 secretion and release remains unknown. In the present study, we investigated the roles of microglia-derived MPO/HOCl in mediating HMGB1 translocation and secretion, and aggravating the brain damage and blood-brain barrier (BBB) disruption in cerebral I/R injury. In vitro, under the co-culture conditions with microglia BV cells but not the single culture conditions, oxygen-glucose deprivation/reoxygenation (OGD/R) significantly increased MPO/HOCl expression in PC12 cells. After the cells were exposed to OGD/R, MPO-containing exosomes derived from BV2 cells were released and transferred to PC12 cells, increasing MPO/HOCl in the PC12 cells. The HOCl promoted disulfide HMGB1 translocation and secretion and aggravated OGD/R-induced apoptosis. In vivo, SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) plus different periods of reperfusion. Increased MPO/HOCl production was observed at the reperfusion stage, accomplished with enlarged infarct volume, aggravated BBB disruption and neurological dysfunctions. Treatment of MPO inhibitor 4-aminobenzoic acid hydrazide (4-ABAH) and HOCl scavenger taurine reversed those changes. HOCl was colocalized with cytoplasm transferred HMGB1, which was blocked by taurine in rat I/R-injured brain. We finally performed a clinical investigation and found that plasma HOCl concentration was positively correlated with infarct volume and neurological deficit scores in ischemic stroke patients. Taken together, we conclude that ischemia/hypoxia could activate microglia to release MPO-containing exosomes that transfer MPO to adjacent cells for HOCl production; Subsequently, the production of HOCl could mediate the translocation and secretion of disulfide HMGB1 that aggravates cerebral I/R injury. Furthermore, plasma HOCl level could be a novel biomarker for indexing brain damage in ischemic stroke patients.

Polyphenolic oligomer-derived multienzyme activity for the treatment of ischemic Stroke through ROS scavenging and blood-brain barrier restoration

Oxidative stress and blood-brain barrier (BBB) injury are two major stress disorders before and after ischemic stroke (IS) therapy. The intense inflammatory response also causes damage to nerve cells, affecting the repair of brain tissue. In this study, polyphenolic nanoparticles (PPNs) with strong free radical scavenging ability were designed to treat IS multimodally. To investigate the mechanism of polyphenolic polymerization, solid nanoparticles were synthesized using four kinds of polyphenol compounds as the basic unit under the control of temperature. The form of polymerization between monomers with different structures led to changes in the chemical properties of the corresponding nanoparticles as well as the antioxidant capacity at the cellular level. Particularly, PPNs can significantly improve cerebral infarction and penetrate and repair the BBB, and even downregulate levels of inflammatory cytokines. Molecular signaling pathway studies have shown that PPNs can provide comprehensive treatment of IS by promoting the expression of tight junction protein and enhancing the activity of antioxidant enzymes. Therefore, PPNs combined with the antioxidant, anti-inflammatory and BBB repair ability not only provide a perfect therapeutic pathway but also give ideas for the development of natural material carriers that have a wide application prospect.

PSD-95 inhibitor Tat-NR2B9c (NA-1) protects the integrity of the blood-brain barrier after transient middle artery occlusion in rats by downregulating matrix metalloprotease-9 and upregulating endothelial nitric oxide synthase

BACKGROUND

Protection against ischemic stroke may be most effective when multiple components of the neurovascular unit are protected, yet current treatments target mainly neurons. Here we explored whether the PSD-95 inhibitor Tat-NR2B9c (NA-1) can protect not only neurons but also the blood-brain barrier.

METHODS

Adult male Sprague-Dawley rats were randomly divided into three groups, which were subjected to either sham surgery or transient cerebral ischemia-reperfusion, after which some animals were treated with Tat-NR2B9c. The therapeutic efficacy of Tat-NR2B9c was assessed in terms of the degree of neurological deficit and cerebral infarction, integrity of the blood-brain barrier, cerebral water content, as well as expression of PSD-95, nitric oxide synthase, and matrix metalloprotease-9.

RESULTS

Tat-NR2B9c (NA-1) ameliorated neurofunctional deficit, reduced cerebral infarction, mitigated blood-brain barrier injury and improved its integrity following ischemia-reperfusion, leading to less cerebral edema. These improvements were associated with upregulation of tight junction proteins in the blood-brain barrier. At the same time, Tat-NR2B9c (NA-1) downregulated neuronal nitric oxide synthase and matrix metalloprotease-9, while reversing the ischemia-induced downregulation of endothelial nitric oxide synthase in brain. We report here the first evidence that PSD-95 is expressed in vascular endothelial cells in the brain.

CONCLUSION

Our experiments in a rat model of transient occlusion of the middle cerebral artery suggest that Tat-NR2B9c (NA-1) can mitigate ischemic injury to the blood-brain barrier, and that it may do so by downregulating matrix metalloprotease-9 and upregulating endothelial nitric oxide synthase.

Clearance dysfunction of trans-barrier transport and lymphatic drainage in cerebral small vessel disease: Review and prospect

Cerebral small vessel disease (CSVD) causes 20%-25% of stroke and contributes to 45% of dementia cases worldwide. However, since its early symptoms are inconclusive in addition to the complexity of the pathological basis, there is a rather limited effective therapies and interventions. Recently, accumulating evidence suggested that various brain-waste-clearance dysfunctions are closely related to the pathogenesis and prognosis of CSVD, and after a comprehensive and systematic review we classified them into two broad categories: trans-barrier transport and lymphatic drainage. The former includes blood brain barrier and blood-cerebrospinal fluid barrier, and the latter, glymphatic-meningeal lymphatic system and intramural periarterial drainage pathway. We summarized the concepts and potential mechanisms of these clearance systems, proposing a relatively complete framework for elucidating their interactions with CSVD. In addition, we also discussed recent advances in therapeutic strategies targeting clearance dysfunction, which may be an important area for future CSVD research.

Biomimetic nanoparticles in ischemic stroke therapy

Abstract

Ischemic stroke is one of the most severe neurological disorders with limited therapeutic strategies. The utilization of nanoparticle drug delivery systems is a burgeoning field and has been widely investigated. Among these, biomimetic drug delivery systems composed of biogenic membrane components and synthetic nanoparticles have been extensively highlighted in recent years. Biomimetic membrane camouflage presents an effective strategy to prolong circulation, reduce immunogenicity and enhance targeting. For one thing, biomimetic nanoparticles reserve the physical and chemical properties of intrinsic nanoparticle. For another, the biological functions of original source cells are completely inherited. Compared to conventional surface modification methods, this approach is more convenient and biocompatible. In this review, membrane-based nanoparticles derived from different donor cells were exemplified. The prospect of future biomimetic nanoparticles in ischemic stroke therapy was discussed.

Graphic abstract

Escin avoids hemorrhagic transformation in ischemic stroke by protecting BBB through the AMPK/Cav-1/MMP-9 pathway

BACKGROUND

Hemorrhagic transformation (HT) seriously affects the clinical application of recombinant tissue plasminogen activator (rt-PA). The main strategy for combating HT is to keep the blood-brain barrier (BBB) stable. Escin is the active ingredient of Aesculus hippocastanum and a natural mixture of triterpene saponins, and may play a part in mitigation of HT.

PURPOSE

This study sought to investigate the effect of Escin in improving rt-PA-induced HT, explore possible mechanisms, and provide new ideas for the treatment of clinical HT.

STUDY DESIGN AND METHODS

In in vivo experiments, transient middle cerebral artery occlusion (tMCAO) was undertaken in 6-week-old and 12-month-old mice, and rt-PA was administered to induce HT injury. The inhibitory effect of Escin on HT and its protective effect on neurobehavior, the BBB, and cerebrovascular endothelial cells was determined. In in vitro experiments, bEnd.3 cells were injured by oxygen-glucose deprivation/reperfusion (OGD/R) and rt-PA. The protective effect of Escin was measured by the CCK8 assay, release of lactate dehydrogenase (LDH), and expression of tight junction (TJ) proteins. In mechanistic studies, the effect of Escin on the adenosine monophosphate-activated kinase / caveolin-1 / matrix metalloprotease-9 (AMPK/Cav-1/MMP-9) pathway was investigated by employing AMPK inhibitor and Cav-1 siRNA.

RESULTS

In mice suffering from ischemia, rt-PA caused HT as well as damage to the BBB and cerebrovascular endothelial cells. Escin reduced the infarct volume, cerebral hemorrhage, improved neurobehavioral deficits, and maintained BBB integrity in rt-PA-treated tMCAO mice while attenuating bEnd.3 cells damage caused by rt-PA and OGD/R injury. Under physiological and pathological conditions, Escin increased the expression of p-AMPK and Cav-1, leading to decreased expression of MMP-9, which further attenuated damage to cerebrovascular endothelial cells, and these effects were verified with AMPK inhibitor and Cav-1 siRNA.

CONCLUSION

We revealed important details of how Escin protects cerebrovascular endothelial cells from HT, these effects were associated with the AMPK/Cav-1/MMP-9 pathway. This study provides experimental foundation for the development of new drugs to mitigate rt-PA-induced HT and the discovery of new clinical application for Escin.

The role of traditional herbal medicine for ischemic stroke: from bench to clinic-A critical review

BACKGROUND

Ischemic stroke (IS) is a leading cause of death and severe long-term disability worldwide. Over the past few decades, considerable progress has been made in anti-ischemic therapies. However, IS remains a tremendous challenge, with favourable clinical outcomes being generally difficult to achieve from candidate drugs in preclinical phase testing. Traditional herbal medicine (THM) has been used to treat stroke for over 2,000 years in China. In modern times, THM as an alternative and complementary therapy have been prescribed in other Asian countries and have gained increasing attention for their therapeutic effects. These millennia of clinical experience allow THM to be a promising avenue for improving clinical efficacy and accelerating drug discovery.

PURPOSE

To summarise the clinical evidence and potential mechanisms of THMs in IS.

METHODS

A comprehensive literature search was conducted in seven electronic databases, including PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, the Chinese National Knowledge Infrastructure, the VIP Information Database, the Chinese Biomedical Literature Database, and the Wanfang Database, from inception to 17 June 2022 to examine the efficacy and safety of THM for IS, and to investigate experimental studies regarding potential mechanisms.

RESULTS

THM is widely prescribed for IS alone or as adjuvant therapy. In clinical trials, THM is generally administered within 72 h of stroke onset and are continuously prescribed for over 3 months. Compared with Western medicine (WM), THM combined with routine WM can significantly improve neurological function defect scores, promote clinical total effective rate, and accelerate the recovery time of stroke with fewer adverse effects (AEs). These effects can be attributed to multiple mechanisms, mainly anti-inflammation, antioxidative stress, anti-apoptosis, brain blood barrier (BBB) modulation, inhibition of platelet activation and thrombus formation, and promotion of neurogenesis and angiogenesis.

CONCLUSIONS

THM may be a promising candidate for IS management to guide clinical applications and as a reference for drug development.

Ancient Chinese Herbal Recipe Huanglian Jie Du Decoction for Ischemic Stroke: An Overview of Current Evidence

Ischemic stroke is a major cause of mortality and neurological morbidity worldwide. The underlying pathophysiology of ischemic stroke is highly complicated and correlates with various pathological processes, including neuroinflammation, oxidative stress injury, altered cell apoptosis and autophagy, excitotoxicity, and acidosis. The current treatment for ischemic stroke is limited to thrombolytic therapy such as recombinant tissue plasminogen activator. However, tissue plasminogen activator is limited by a very narrow therapeutic time window (<4.5 hours), selective efficacy, and hemorrhagic complication. Hence, the development of novel therapies to prevent ischemic damage to the brain is urgent. Chinese herbal medicine has a long history in treating stroke and its sequela. In the past decades, extensive studies have focused on the neuroprotective effects of Huanglian Jie Du decoction (HLJDD), an ancient and classical Chinese herbal formula that can treat a wide spectrum of disorders including ischemic stroke. In this review, the current evidence of HLJDD and its bioactive components for ischemic stroke is comprehensively reviewed, and their potential application directions in ischemic stroke management are discussed.

Protective effects of brain-targeted dexmedetomidine nanomicelles on mitochondrial dysfunction in astrocytes of cerebral ischemia/reperfusion injury rats

Cerebral ischemia/reperfusion injury (CIRI) is closely related to mitochondrial dysfunction in astrocytes. Therefore, based on glucose transporter 1 (GLUT1), which is highly expressed in the brain tissue of rats with CIRI, we design a kind of brain-targeted dexmedetomidine (Man@Dex) nanomicelles. The results showed that Man@Dex not only had the advantages of small particle size, stability and non-toxicity, but also realized brain-targeted drug delivery. Primary astrocytes were cultured in vitro to construct CIRI cell model. It was found that Man@Dex could improve the activity of injured astrocytes. Man@Dex could exert antioxidant activity by inhibiting the reactive oxygen species (ROS) production of astrocytes, thus inhibiting the cytotoxicity induced by hypoxia and reoxygenation. Man@Dex could improve the ATP level and mitochondrial membrane potential (MMP) to protect mitochondrial function of damaged astrocytes. The CIRI rat model was constructed and confirmed by hematoxylin and eosin (HE), Triphenyl-2H-tetrazolium chloride (TTC) staining and nerve defect score. It indicated that Man@Dex could alleviate CIRI and improve MMP, which was beneficial to the recovery of brain injury in rats. This research provides a new theoretical basis and target for the development of brain-targeted nano-drugs of CIRI.

The Putative Role of Astaxanthin in Neuroinflammation Modulation: Mechanisms and Therapeutic Potential

Neuroinflammation is a protective mechanism against insults from exogenous pathogens and endogenous cellular debris and is essential for reestablishing homeostasis in the brain. However, excessive prolonged neuroinflammation inevitably leads to lesions and disease. The use of natural compounds targeting pathways involved in neuroinflammation remains a promising strategy for treating different neurological and neurodegenerative diseases. Astaxanthin, a natural xanthophyll carotenoid, is a well known antioxidant. Mounting evidence has revealed that astaxanthin is neuroprotective and has therapeutic potential by inhibiting neuroinflammation, however, its functional roles and underlying mechanisms in modulating neuroinflammation have not been systematically summarized. Hence, this review summarizes recent progress in this field and provides an update on the medical value of astaxanthin. Astaxanthin modulates neuroinflammation by alleviating oxidative stress, reducing the production of neuroinflammatory factors, inhibiting peripheral inflammation and maintaining the integrity of the blood-brain barrier. Mechanistically, astaxanthin scavenges radicals, triggers the Nrf2-induced activation of the antioxidant system, and suppresses the activation of the NF-κB and mitogen-activated protein kinase pathways. With its good biosafety and high bioavailability, astaxanthin has strong potential for modulating neuroinflammation, although some outstanding issues still require further investigation.

Diabetes complications and extracellular vesicle therapy

Diabetes is a chronic disorder characterized by dysregulated glycemic conditions. Diabetic complications include microvascular and macrovascular abnormalities and account for high morbidity and mortality rates in patients. Current clinical approaches for diabetic complications are limited to symptomatic treatments and tight control of blood sugar levels. Extracellular vesicles (EVs) released by somatic and stem cells have recently emerged as a new class of potent cell-free therapeutic delivery packets with a great potential to treat diabetic complications. EVs contain a mixture of bioactive molecules and can affect underlying pathological processes in favor of tissue healing. In addition, EVs have low immunogenicity and high storage capacity while maintaining nearly the same regenerative and immunomodulatory effects compared to current cell-based therapies. Therefore, EVs have received increasing attention for diabetes-related complications in recent years. In this review, we provide an outlook on diabetic complications and summarizes new knowledge and advances in EV applications. Moreover, we highlight recommendations for future EV-related research.

Efficacy of Chinese herbal medicine for tPA thrombolysis in experimental stroke: A systematic review and meta-analysis

BACKGROUND

Tissue-type plasminogen activator (tPA) remains the sole FDA approved thrombolytic drug for ischemic stroke. But delayed thrombolytic therapy with tPA may increase the risk of hemorrhagic transformation. Many Chinese herbal medicines have been used as tPA helpers to enhance the capacity of tPA and minimize the risk of hemorrhagic transformation. The efficacy of Chinese herbal medicines on tPA thrombolysis is not systematically analyzed.

METHODS

We searched the following three databases up to January 2022: Web of Science, PubMed, and Scopus. Studies that reported the efficacy and safety of Chinese herbal medicines on tPA thrombolysis in experimental stroke were included. The efficacy outcomes were neurological score and infarct volume, the safety outcomes were cerebral hemorrhage and blood brain barrier (BBB) damage. We used the checklist of CAMARADES to assess the quality of included studies. Standardized mean difference (SMD) with 95% confidence intervals were used to assess all the outcomes. Subgroup analyses were performed to explore the sources of heterogeneity. Trim and fill method and Egger's test were used to assess the potential publication bias. Sensitivity analyses were used to identify the stability of the results.

RESULTS

A total of nine studies including 11 Chinese herbal medicines fulfilled the inclusion criteria and were subsequently analyzed. The pooled data demonstrated that Chinese herbal medicines improved neurological score (2.23 SMD, 1.42-3.04), infarct volume (1.08 SMD, 0.62-1.54), attenuated cerebral hemorrhage (1.87 SMD, 1.34-2.4), and BBB dysfunction (1.9 SMD, 1.35-2.45) following tPA thrombolysis in experimental stroke. Subgroup analysis indicated that the route of drug delivery, dosage of tPA, and stroke model used may be factors inducing heterogeneity and influencing the efficacy.

CONCLUSION

Treatment with Chinese herbal medicines significantly improved neurological score and infarct volume, reduced cerebral hemorrhage and BBB damage after tPA thrombolysis. This study supports Chinese herbal medicine as an adjuvant therapy in reducing the side effects of tPA thrombolysis after acute ischemic stroke. The results should be interpreted with more caution since this article was based on animal studies.

Angong Niuhuang Wan reduces hemorrhagic transformation and mortality in ischemic stroke rats with delayed thrombolysis: involvement of peroxynitrite-mediated MMP-9 activation

Background

Hemorrhagic transformation (HT) is a common complication of delayed tissue plasminogen activator (t-PA) treatment for ischemic stroke. Peroxynitrite plays an important role in the breakdown of blood–brain barrier (BBB) and the development of HT. We tested the hypothesis that Angong Niuhuang Wan (AGNHW), a traditional Chinese medicinal formula, could be used in conjunction with t-PA to protect the BBB, minimize HT, and improve neurological function by suppressing peroxynitrite-mediated matrix metalloproteinase-9 (MMP-9) activation.

Methods

We first performed quality control study and chemical identification of AGNHW by using UPLC. In animal experiments, male Sprague–Dawley rats were subjected to 5 h of middle cerebral artery occlusion (MCAO) followed by 19 h of reperfusion plus t-PA infusion (10 mg/kg) at 5 h of cerebral ischemia. AGNHW (257 mg/kg) was given orally at 2 h after MCAO. Hemorrhagic transformation was measured using hemorrhagic scores and hemoglobin levels in ischemic brains. Evans blue leakage was utilized to assess the severity of the blood–brain barrier (BBB) damage. The modified neurologic severity score (mNSS) test was used to assess neurological functions. Peroxynitrite and superoxide was detected by using fluorescent probes. MMP-9 activity and expression were examined by gelatin zymography and immunostaining. The antioxidant effects were also studied by using brain microvascular endothelial b.End3 cells exposed to 5 h of oxygen and glucose deprivation (OGD) plus 5 h of reoxygenation with t-PA treatment (20 µg/ml).

Results

AGNHW significantly reduced the BBB damage, brain edema, reduced hemorrhagic transformation, enhanced neurological function, and reduced mortality rate in the ischemic stroke rats with t-PA treatment. AGNHW reduced peroxynitrite and superoxide in vivo and in vitro and six active chemical compounds were identified from AGNHW with peroxynitrite scavenging activity. Furthermore, AGNHW inhibited MMP-9 activity, and preserved tight junction protein claudin-5 and collagen IV in the ischemic brains.

Conclusion

AGNHW could be a potential adjuvant therapy with t-PA to protect the BBB integrity, reduce HT, and improve therapeutic outcome in ischemic stroke treatment via inhibiting peroxynitrite-mediated MMP-9 activation.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00595-7.

Roles of Nitric Oxide in Brain Ischemia and Reperfusion

Brain ischemia and reperfusion (I/R) is one of the most severe clinical manifestations of ischemic stroke, placing a significant burden on both individuals and society. The only FDA-approved clinical treatment for ischemic stroke is tissue plasminogen activator (t-PA), which rapidly restores cerebral blood flow but can have severe side effects. The complex pathological process of brain I/R has been well-established in the past few years, including energy metabolism disorders, cellular acidosis, doubling of the synthesis or release of excitotoxic amino acids, intracellular calcium homeostasis, free radical production, and activation of apoptotic genes. Recently, accumulating evidence has shown that NO may be strongly related to brain I/R and involved in complex pathological processes. This review focuses on the role of endogenous NO in pathological processes in brain I/R, including neuronal cell death and blood brain barrier disruption, to explore how NO impacts specific signaling cascades and contributes to brain I/R injury. Moreover, NO can rapidly react with superoxide to produce peroxynitrite, which may also mediate brain I/R injury, which is discussed here. Finally, we reveal several therapeutic approaches strongly associated with NO and discuss their potential as a clinical treatment for ischemic stroke.

Elucidating the Synergistic Effect of Multiple Chinese Herbal Prescriptions in the Treatment of Post-stroke Neurological Damage

Background: Traditional Chinese medicine (TCM) has been widely used in the treatment of human diseases. However, the synergistic effects of multiple TCM prescriptions in the treatment of stroke have not been thoroughly studied.

Objective of the study: This study aimed to reveal the mechanisms underlying the synergistic effects of these TCM prescriptions in stroke treatment and identify the active compounds.

Methods: Herbs and compounds in the Di-Tan Decoction (DTD), Xue-Fu Zhu-Yu Decoction (XFZYD), and Xiao-Xu-Ming Decoction (XXMD) were acquired from the TCMSP database. SEA, HitPick, and TargetNet web servers were used for target prediction. The compound-target (C-T) networks of three prescriptions were constructed and then filtered using the collaborative filtering algorithm. We combined KEGG enrichment analysis, molecular docking, and network analysis approaches to identify active compounds, followed by verification of these compounds with an oxygen-glucose deprivation and reoxygenation (OGD/R) model.

Results: The filtered DTD network contained 39 compounds and 534 targets, the filtered XFZYD network contained 40 compounds and 508 targets, and the filtered XXMD network contained 55 compounds and 599 targets. The filtered C-T networks retained approximately 80% of the biological functions of the original networks. Based on the enriched pathways, molecular docking, and network analysis results, we constructed a complex network containing 3 prescriptions, 14 botanical drugs, 26 compounds, 13 targets, and 5 pathways. By calculating the synergy score, we identified the top 5 candidate compounds. The experimental results showed that quercetin, baicalin, and ginsenoside Rg1 independently and synergistically increased cell viability.

Conclusion: By integrating pharmacological and chemoinformatic approaches, our study provides a new method for identifying the effective synergistic compounds of TCM prescriptions. The filtered compounds and their synergistic effects on stroke require further research.

Traditional Chinese medicine use in the pathophysiological processes of intracerebral hemorrhage and comparison with conventional therapy

Intracerebral hemorrhage (ICH) refers to hemorrhage caused by non-traumatic vascular rupture in the brain parenchyma, which is characterized by acute onset, severe illness, and high mortality and disability. The influx of blood into the brain tissue after cerebrovascular rupture causes severe brain damage, including primary injury caused by persistent hemorrhage and secondary brain injury (SBI) induced by hematoma. The mechanism of brain injury is complicated and is a significant cause of disability after ICH. Therefore, it is essential to understand the mechanism of brain injury after ICH to develop drugs to prevent and treat ICH. Studies have confirmed that many traditional Chinese medicines (TCM) can reduce brain injury by improving neurotoxicity, inflammation, oxidative stress (OS), blood-brain barrier (BBB), apoptosis, and neurological dysfunction after ICH. Starting from the pathophysiological process of brain injury after ICH, this paper summarizes the mechanisms by which TCM improves cerebral injury after ICH and its comparison with conventional western medicine, so as to provide clues and a reference for the clinical application of TCM in the prevention and treatment of hemorrhagic stroke and further research and development of new drugs.

Changes of FSTL1 and MMP-9 levels in patients with acute cerebral infarction and its relationship with hemorrhagic transformation

BACKGROUND

hemorrhagic transformation is a serious complication of acute ischemic stroke, which may lead to poor prognosis and delayed use of anticoagulant therapy.

METHODS

125 patients with cerebral infarction from December 2019 to December 2020 in the Second Affiliated Hospital of Zhejiang University were selected. All patients did not receive intravascular therapy, intravenous thrombolysis and other reperfusion treatment; and the relevant laboratory data were collected within 24 h after admission. At the same time, 15 healthy subjects were selected as the research objects for prospective analysis. Hemorrhagic transformation (HT) was defined as a condition in which computed tomography (CT) did not indicate bleeding at admission, but follow-up magnetic resonance imaging (MRI) or CT showed hemorrhage. The patients were divided into HT group (n = 50) and non-HT group (n = 75) according to whether there was HT after admission. The concentrations of FSTL1 and MMP-9 in peripheral blood of the two groups were detected.

RESULTS

The concentrations of FSTL1 and MMP-9 in acute cerebral infarction (ACI) group were significantly higher than those in control group. However the HT group had a higher concentration of FSTL1 and MMP-9 than the non-HT group. The serum FSTL1 and MMP-9 were independent risk factors for hemorrhagic transformation. The area under the ROC curve of FSTL1 and MMP-9 in diagnosis of HT was 0.809 and 0.856 respectively, and their combined value was 0.923.

CONCLUSION

The high levels of FSTL1 and MMP-9 had strong correlation with HT in ACI patients.

The mechanism of HMGB1 secretion and release

High mobility group box 1 (HMGB1) is a nonhistone nuclear protein that has multiple functions according to its subcellular location. In the nucleus, HMGB1 is a DNA chaperone that maintains the structure and function of chromosomes. In the cytoplasm, HMGB1 can promote autophagy by binding to BECN1 protein. After its active secretion or passive release, extracellular HMGB1 usually acts as a damage-associated molecular pattern (DAMP) molecule, regulating inflammation and immune responses through different receptors or direct uptake. The secretion and release of HMGB1 is fine-tuned by a variety of factors, including its posttranslational modification (e.g., acetylation, ADP-ribosylation, phosphorylation, and methylation) and the molecular machinery of cell death (e.g., apoptosis, pyroptosis, necroptosis, alkaliptosis, and ferroptosis). In this minireview, we introduce the basic structure and function of HMGB1 and focus on the regulatory mechanism of HMGB1 secretion and release. Understanding these topics may help us develop new HMGB1-targeted drugs for various conditions, especially inflammatory diseases and tissue damage.

A nuclear protein that gets released after cell death or is actively secreted by immune cells offers a promising therapeutic target for treating diseases linked to excessive inflammation. Daolin Tang from the University of Texas Southwestern Medical Center in Dallas, USA, and colleagues review how cellular stresses can trigger the accumulation of HMGB1, a type of alarm signal protein that promotes the recruitment and activation of inflammation-promoting immune cells. The researchers discuss various mechanisms that drive both passive and active release of HMGB1 into the space around cells. These processes, which include enzymatic modifications of the HMGB1 protein, cell–cell interactions and molecular pathways of cell death, could be targeted by drugs to lessen tissue damage and inflammatory disease caused by HMGB1-induced immune responses

GAS6/Axl Signaling Modulates Blood-Brain Barrier Function Following Intravenous Thrombolysis in Acute Ischemic Stroke

Background and Purpose

Recent studies have shown that several proteins, including Axl, are related to hemorrhagic transformation (HT) following intravenous thrombolysis by affecting blood-brain barrier (BBB) function. However, the effects of these proteins on BBB function have been studied primarily in animal models. In this study, we aimed to identify serum protein markers that predict HT following intravenous thrombolysis in patients with acute ischemic stroke (AIS) and verify whether these serum proteins regulate BBB function and HT in animal stroke models.

Methods

First, 118 AIS patients were enrolled in this study, including 52 HT patients and 66 non-HT patients. In Step 1, baseline serum levels of Axl, angiopoietin-like 4, C-reactive protein, ferritin, hypoxia-inducible factor-1 alpha, HTRA2, Lipocalin2, matrix metallopeptidase 9, platelet-derived growth factor-BB, and tumor necrosis factor alpha were measured using a quantitative cytokine chip. Next, sequence mutations and variations in genes encoding the differentially expressed proteins identified in Step 1 and subsequent function-related proteins were detected. Finally, we verified whether manipulation of differentially expressed proteins affected BBB function and HT in a hyperglycemia-induced rat stroke model.

Results

Serum Axl levels were significantly lower in the HT group than in the non-HT group; none of the other protein markers differed significantly between the two groups. Genetic testing revealed that sequence variations of GAS6 (the gene encoding the Axl ligand)-derived long non-coding RNA, GAS6-AS1, were significantly correlated with an increased risk of HT after intravenous thrombolysis. In animal studies, administration of recombinant GAS6 significantly reduced brain infarction and neurological deficits and attenuated BBB disruption and HT.

Conclusions

Lower serum Axl levels, which may result from sequence variations in GAS6-AS1, are correlated with an increased risk of HT after intravenous thrombolysis in stroke patients. Activation of the Axl signaling pathway by the GAS6 protein may serve as a therapeutic strategy to reduce HT in AIS patients.

BMSCs Regulate Astrocytes through TSG-6 to Protect the Blood-Brain Barrier after Subarachnoid Hemorrhage

Background

In patients with subarachnoid hemorrhage (SAH), the damage of the blood-brain barrier (BBB) can be life-threatening. Mesenchymal stem cells are widely used in clinical research due to their pleiotropic properties. This study is aimed at exploring the effect of BMSCs regulating astrocytes on the BBB after SAH.

Methods

The SAH model was established by perforating the blood vessels. BMSCs were transfected with TSG-6 inhibitor plasmid and cocultured with astrocytes. Intravenous transplantation of BMSCs was utilized to treat SAH rats. We performed ELISA, neurological scoring, Evans blue staining, NO measurement, immunofluorescence, BBB permeability, Western blot, HE staining, Nissl staining, and immunohistochemistry to evaluate the effect of BMSCs on astrocytes and BBB.

Results

SAH rats showed BBB injury, increased BBB permeability, and brain histological damage. BMSCs will secrete TSG-6 after being activated by TNF-α. Under the influence of TSG-6, the NF-κB and MAPK signaling pathways of astrocytes were inhibited. The expression of iNOS was reduced, while occludin, claudin 3, and ZO-1 expression was increased. The production of harmful substances NO and ONOO^- decreased. The level of inflammatory factors decreased. The apoptosis of astrocytes was weakened. TSG-6 secreted by BMSCs can relieve inflammation caused by SAH injury. The increase in BBB permeability of SAH rats was further reduced and the risk of rebleeding was reduced.

Conclusion

BMSCs can regulate the activation of astrocytes through secreting TSG-6 in vivo and in vitro to protect BBB.

Natural Products in the Prevention of Metabolic Diseases: Lessons Learned from the 20th KAST Frontier Scientists Workshop

The incidence of metabolic and chronic diseases including cancer, obesity, inflammation-related diseases sharply increased in the 21st century. Major underlying causes for these diseases are inflammation and oxidative stress. Accordingly, natural products and their bioactive components are obvious therapeutic agents for these diseases, given their antioxidant and anti-inflammatory properties. Research in this area has been significantly expanded to include chemical identification of these compounds using advanced analytical techniques, determining their mechanism of action, food fortification and supplement development, and enhancing their bioavailability and bioactivity using nanotechnology. These timely topics were discussed at the 20th Frontier Scientists Workshop sponsored by the Korean Academy of Science and Technology, held at the University of Hawaii at Manoa on 23 November 2019. Scientists from South Korea and the U.S. shared their recent research under the overarching theme of Bioactive Compounds, Nanoparticles, and Disease Prevention. This review summarizes presentations at the workshop to provide current knowledge of the role of natural products in the prevention and treatment of metabolic diseases.

Neuroprotective Effects of Salicin in a Gerbil Model of Transient Forebrain Ischemia by Attenuating Oxidative Stress and Activating PI3K/Akt/GSK3β Pathway

Salicin is a major natural compound of willow bark and displays diverse beneficial biological properties, such as antioxidant activity. However, little information available for the neuroprotective potential of salicin against ischemic brain injury has been reported. Thus, this study was performed to investigate the neuroprotective potential of salicin against ischemia and reperfusion (IR) injury and its mechanisms in the hippocampus using a gerbil model of 5-min transient ischemia (TI) in the forebrain, in which a massive loss (death) of pyramidal neurons cells occurred in the subfield Cornu Ammonis 1 (CA1) among the hippocampal subregions (CA1-3) at 5 days after TI. To examine neuroprotection by salicin, gerbils were pretreated with salicin alone or together with LY294002, which is a phosphatidylinositol 3-kinase (PI3K) inhibitor, once daily for 3 days before TI. Treatment with 20 mg/kg of salicin significantly protected CA1 pyramidal neurons against the ischemic injury. Treatment with 20 mg/kg of salicin significantly reduced the TI-induced increase in superoxide anion generation and lipid peroxidation in the CA1 pyramidal neurons after TI. The treatment also reinstated the TI-induced decrease in superoxide dismutases (SOD1 and SOD2), catalase, and glutathione peroxidase in the CA1 pyramidal cells after TI. Moreover, salicin treatment significantly elevated the levels of phosphorylation of Akt and glycogen synthase kinase-3β (GSK3β), which is a major downstream target of PI3K, in the ischemic CA1. Notably, the neuroprotective effect of salicin was abolished by LY294002. Taken together, these findings clearly indicate that salicin protects against ischemic brain injury by attenuating oxidative stress and activating the PI3K/Akt/GSK3β pathway.

Danggui-Shaoyao-San (DSS) Ameliorates Cerebral Ischemia-Reperfusion Injury via Activating SIRT1 Signaling and Inhibiting NADPH Oxidases

Danggui-Shayao-San (DSS) is a famous Traditional Chinese Medicine formula that used for treating pain disorders and maintaining neurological health. Recent studies indicate that DSS has neuroprotective effects against ischemic brain damage but its underlining mechanisms remain unclear. Herein, we investigated the neuroprotective mechanisms of DSS for treating ischemic stroke. Adult male Sprague-Dawley (S.D.) rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) plus 22 h of reperfusion. Both ethanol extract and aqueous extract of DSS (12 g/kg) were orally administrated into the rats at 30 min prior to MCAO ischemic onset. We found that 1) ethanol extract of DSS, instead of aqueous extract, reduced infarct sizes and improved neurological deficit scores in the post-ischemic stroke rats; 2) Ethanol extract of DSS down-regulated the expression of the cleaved-caspase 3 and Bax, up-regulated bcl-2 and attenuated apoptotic cell death in the ischemic brains; 3) Ethanol extract of DSS decreased the production of superoxide and peroxynitrite; 4) Ethanol extract of DSS significantly down-regulated the expression of p67^phox but has no effect on p47^phox and iNOS statistically. 5) Ethanol extract of DSS significantly up-regulated the expression of SIRT1 in the cortex and striatum of the post-ischemic brains; 6) Co-treatment of EX527, a SIRT1 inhibitor, abolished the DSS’s neuroprotective effects. Taken together, DSS could attenuate oxidative/nitrosative stress and inhibit neuronal apoptosis against cerebral ischemic-reperfusion injury via SIRT1-dependent manner.

Danhong Injection Attenuates Cerebral Ischemia-Reperfusion Injury in Rats Through the Suppression of the Neuroinflammation

Neuroinflammation is one of the major causes of damage of the central nervous system (CNS) and plays a vital role in the pathogenesis of cerebral ischemia, which can result in long-term disability and neuronal death. Danhong injection (DHI), a traditional Chinese medicine injection, has been applied to the clinical treatment of cerebral stoke for many years. In this study, we investigated the protective effects of DHI on cerebral ischemia-reperfusion injury (CIRI) in rats and explored its potential anti-neuroinflammatory properties. CIRI in adult male SD rats was induced by middle cerebral artery occlusion (MCAO) for 1 h and reperfusion for 24 h. Results showed that DHI (0.5, 1, and 2 ml/kg) dose-dependently improved the neurological deficits and alleviated cerebral infarct volume and histopathological damage of the cerebral cortex caused by CIRI. Moreover, DHI (0.5, 1, and 2 ml/kg) inhibited the mRNA expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), intercellular cell adhesion molecule-1 (ICAM-1), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) in ischemic brains, downregulated TNF-α, IL-1β, and monocyte chemotactic protein-1 (MCP-1) levels in serum, and reduced the neutrophil infiltration (myeloperoxidase, MPO) in ischemic brains, in a dose-dependent manner. Immunohistochemical staining results also revealed that DHI dose-dependently diminished the protein expressions of ICAM-1 and COX-2, and suppressed the activation of microglia (ionized calcium-binding adapter molecule 1, Iba-1) and astrocyte (glial fibrillary acidic protein, GFAP) in the cerebral cortex. Western blot analysis showed that DHI significantly downregulated the phosphorylation levels of the proteins in nuclear factor κB (NF-κB) and mitogen-activated protein kinas (MAPK) signaling pathways in ischemic brains. These results indicate that DHI exerts anti-neuroinflammatory effects against CIRI, which contribute to the amelioration of CNS damage.

Classical Active Ingredients and Extracts of Chinese Herbal Medicines: Pharmacokinetics, Pharmacodynamics, and Molecular Mechanisms for Ischemic Stroke

Stroke is a leading cause of death and disability worldwide, and approximately 87% of cases are attributed to ischemia. The main factors that cause ischemic stroke include excitotoxicity, energy metabolism disorder, Ca⁺ overload, oxidative damage, apoptosis, autophagy, and inflammation. However, no effective drug is currently available for the comprehensive treatment of ischemic stroke in clinical applications; thus, there is an urgent need to find and develop comprehensive and effective drugs to treat postischemic stroke. Traditional Chinese medicine (TCM) has unique advantages in treating ischemic stroke, with overall regulatory effects at multiple levels and on multiple targets. Many researchers have studied the effective components of TCMs and have achieved undeniable results. This paper reviews studies on the anticerebral ischemia effects of TCM monomers such as tetramethylpyrazine (TMP), dl-3-n-butylphthalide (NBP), ginsenoside Rg1 (Rg1), tanshinone IIA (TSA), gastrodin (Gas), and baicalin (BA) as well as effective extracts such as Ginkgo biloba extract (EGB). Research on the anticerebral ischemia effects of TCMs has focused mostly on their antioxidative stress, antiapoptotic, anti-inflammatory, proangiogenic, and proneurogenic effects. However, the research on the use of TCM to treat ischemic stroke remains incompletely characterized. Thus, we summarized and considered this topic from the perspective of pharmacokinetics, pharmacological effects, and mechanistic research, and we have provided a reference basis for future research and development on anticerebral ischemia TCM drugs.

Melatonin Ameliorates Hemorrhagic Transformation via Suppression of ROS-Induced NLRP3 Activation after Cerebral Ischemia in Hyperglycemic Rats

Melatonin is a strong antioxidant which beneficially protects against middle cerebral artery occlusion (MCAO) followed by hemorrhagic transformation in rats; protection includes the reduction of neurological deficits, infarction, and hematoma volume. The molecular mechanisms underlying these neuroprotective effects in the MCAO model have not been clearly identified. This study examined the influence and involved mechanism of melatonin on inflammation in hemorrhagic transformation following hyperglycemia MCAO rat model. Compared with the MCAO group, MCAO+dextrose (DX) group showed worse neurological function and higher infarction and hematoma volume. Interestingly, the protein expression of Nod-like receptor protein 3 (NLRP3) inflammasome increased in the MCAO+DX group compared with the MCAO group, which indicated that NLRP3 inflammasome may be involved in the DX-induced hemorrhagic transformation following MCAO. Then, three dosages of melatonin were intraperitoneally injected 2 h after MCAO induction. Melatonin treatment attenuated inflammatory response by inhibiting the reactive oxygen species (ROS) and NLRP3 inflammasome, alleviating neuronal injury, and reducing infarction and hematoma volume, finally improving neurological score. Melatonin also repressed cortical levels of proinflammatory cytokine IL-1β, which were increased 24 h after hyperglycemia MCAO. In order to identify the potential mechanisms, we further revealed that nigericin administration reversed the neuroprotective effect of melatonin by promoting NLRP3 inflammasome activation. In general, this present study reveals that melatonin prevents the occurrence of hyperglycemia-enhanced hemorrhagic transformation, and this effect might be beneficial to attenuate neurological dysfunction via suppressing the inflammatory response after MCAO which possibly associated with the inhibition of the ROS/NLRP3 inflammasome pathway.

Peroxynitrite activates NLRP3 inflammasome and contributes to hemorrhagic transformation and poor outcome in ischemic stroke with hyperglycemia

This study aims to test the hypothesis that peroxynitrite-mediated inflammasome activation could be a crucial player in the blood-brain barrier (BBB) disruption, hemorrhagic transformation (HT) and poor outcome in ischemic stroke with hyperglycemia. We used an experimental rat stroke model subjected to 90 min of middle cerebral artery occlusion plus 24 h or 7 days of reperfusion with or without acute hyperglycemia. We detected the production of peroxynitrite, the expression of NADPH oxidase, iNOS, MMPs and NLRP3 inflammasome in the ischemic brains, and evaluated infarct volume, brain edema, HT, neurological deficit score and survival rates. Our results show that: (1) Hyperglycemia increased the expression of NADPH oxidase subunits p47phox and p67phox, and iNOS, and the production of peroxynitrite. (2) Hyperglycemia increased infarct volume, aggravated the BBB hyperpermeability, induced brain edema and HT, and worsened neurological outcomes. These brain damages and poor outcome were reversed by the treatments of FeTmPyP (a representative peroxynitrite decomposition catalyst, PDC), peroxynitrite scavenger uric acid, and iNOS inhibitor 1400W. Furthermore, the activations of MMPs and NLRP3 inflammasome including pro/active-caspase-1 and IL-1β were inhibited both PDC and 1400W, indicating the roles of peroxynitrite in the inductions of MMPs and NLRP3 inflammasome in the ischemic brains under hyperglycemia. (3) NLRP3 inflammasome inhibitor MCC950, caspase-1 inhibitor VX-765 and IL-1β inhibitor diacerein attenuated brain edema, minimized hemorrhagic transformation and improved neurological outcome, demonstrating the roles of NLRP3 inflammasome in the hyperglycemia-mediated HT and poor outcome in the ischemic stroke rats with acute hyperglycemia. In conclusion, peroxynitrite could mediate activations of MMPs and NLRP3 inflammasome, aggravate the BBB damage and HT, and induce poor outcome in ischemic stroke with hyperglycemia. Therefore, targeting peroxynitrite-mediated NLRP3 inflammasome could be a promising strategy for ischemic stroke with hyperglycemia.

Neurovascular Units and Neural-Glia Networks in Intracerebral Hemorrhage: from Mechanisms to Translation

Intracerebral hemorrhage (ICH), the most lethal type of stroke, often leads to poor outcomes in the clinic. Due to the complex mechanisms and cell-cell crosstalk during ICH, the neurovascular unit (NVU) was proposed to serve as a promising therapeutic target for ICH research. This review aims to summarize the development of pathophysiological shifts in the NVU and neural-glia networks after ICH. In addition, potential targets for ICH therapy are discussed in this review. Beyond cerebral blood flow, the NVU also plays an important role in protecting neurons, maintaining central nervous system (CNS) homeostasis, coordinating neuronal activity among supporting cells, forming and maintaining the blood-brain barrier (BBB), and regulating neuroimmune responses. During ICH, NVU dysfunction is induced, along with neuronal cell death, microglia and astrocyte activation, endothelial cell (EC) and tight junction (TJ) protein damage, and BBB disruption. In addition, it has been shown that certain targets and candidates can improve ICH-induced secondary brain injury based on an NVU and neural-glia framework. Moreover, therapeutic approaches and strategies for ICH are discussed.

Memantine protects blood-brain barrier integrity and attenuates neurological deficits through inhibiting nitric oxide synthase ser1412 phosphorylation in intracerebral hemorrhage rats: involvement of peroxynitrite-related matrix metalloproteinase-9/NLRP3 inflammasome activation

Memantine has demonstrated beneficial effects on several types of brain insults via therapeutic mechanisms mainly related to its activity as a receptor antagonist of N-methyl-d-aspartate. However, the influences of memantine on intracerebral hemorrhage (ICH) remain obscure. This research probed into the neurovascular protective mechanisms of memantine after ICH and its impacts on neuronal nitric oxide synthase (nNOS) ser1412 phosphorylation. ICH model was established by employing intrastriatal collagenase injection in rats. After modeling, rats were then allocated randomly into sham-operated (sham), vehicle-treated (ICH+V), and memantine-administrated (ICH+M) groups. Memantine (20 mg/kg/day) was intraperitoneally administered 30 min after ICH and thenceforth once daily. Rats were dedicated at 0.25, 6, 12, 24 h, 3 and 7 d post-ICH for measurement of corresponding indexes. Behavioral changes, brain edema, levels of nNOS ser1412 phosphorylation, peroxynitrite, matrix metalloproteinase (MMP)-9, NLRP3, IL-1β and numbers of dying neurons, as well as the cellular localization of gelatinolytic activity, were detected among the groups. Memantine improved the neurologic deficits and mitigated brain water content, levels of MMP-9, NLRP3, IL-1β and dying neurons. Additionally, treatment with memantine also reduced nNOS ser1412 phosphorylation and peroxynitrite formation compared with the ICH+V group at 24 h after ICH. In situ zymography simultaneously revealed that gelatinase activity was primarily colocalized with vessel walls and neurons. We concluded that memantine ameliorated blood-brain barrier disruption and neurologic dysfunction in an ICH rat model. The underlying mechanism might involve repression of nNOS ser1412 phosphorylation, as well as peroxynitrite-related MMP-9 and NLRP3 inflammasome activation.

Nutraceutical induction and mimicry of heme oxygenase activity as a strategy for controlling excitotoxicity in brain trauma and ischemic stroke: focus on oxidative stress

Introduction: Ischemic stroke and traumatic brain injury are leading causes of acute mortality, and in the longer run, major causes of significant mental and physical impairment. Most of the brain neuronal cell death in the minutes and hours following an ischemic stroke or brain trauma is mediated by the process of excitotoxicity, in which sustained elevations of extracellular glutamate, reflecting a failure of ATP-dependent mechanism which sequester glutamate in neurons and astrocytes, drive excessive activation of NMDA receptors. Areas covered: A literature search was undertaken to clarify the molecular mechanisms whereby excessive NMDA activation leads to excitotoxic neuronal death, and to determine what safe nutraceutical agents might have practical potential for rescuing at-risk neurons by intervening in these mechanisms. Expert opinion: Activation of both NADPH oxidase and neuronal nitric oxide synthase in the microenvironment of activated NMDA receptors drives production of superoxide and highly toxic peroxynitrite. This leads to excessive activation of PARP and p38 MAP kinase, mitochondrial dysfunction, and subsequent neuronal death. Heme oxygenase-1 (HO-1) induction offers protection via inhibition of NADPH oxidase and promotion of cGMP generation. Phase 2-inductive nutraceuticals can induce HO-1, and other nutraceuticals can mimic the effects of its products biliverdin and carbon monoxide.

Neuroinflammation in hemorrhagic transformation after tissue plasminogen activator thrombolysis: Potential mechanisms, targets, therapeutic drugs and biomarkers

Hemorrhagic transformation (HT) is a common and serious complication following ischemic stroke, especially after tissue plasminogen activator (t-PA) thrombolysis, which is associated with increased mortality and disability. Due to the unknown mechanisms and targets of HT, there are no effective therapeutic drugs to decrease the incidence of HT. In recent years, many studies have found that neuroinflammation is closely related to the occurrence and development of HT after t-PA thrombolysis, including glial cell activation in the brain, peripheral inflammatory cell infiltration and the release of inflammatory factors, involving inflammation-related targets such as NF-κB, MAPK, HMGB1, TLR4 and NLRP3. Some drugs with anti-inflammatory activity have been shown to protect the BBB and reduce the risk of HT in preclinical experiments and clinical trials, including minocycline, fingolimod, tacrolimus, statins and some natural products. In addition, the changes in MMP-9, VAP-1, NLR, sICAM-1 and other inflammatory factors are closely related to the occurrence of HT, which may be potential biomarkers for the diagnosis and prognosis of HT. In this review, we summarize the potential inflammation-related mechanisms, targets, therapeutic drugs, and biomarkers associated with HT after t-PA thrombolysis and discuss the relationship between neuroinflammation and HT, which provides a reference for research on the mechanisms, prevention and treatment drugs, diagnosis and prognosis of HT.

The Effects and Underlying Mechanisms of Cell Therapy on Blood-Brain Barrier Integrity After Ischemic Stroke

Ischemic stroke is one of the main causes of mortality and disability worldwide. However, efficient therapeutic strategies are still lacking. Stem/progenitor cell-based therapy, with its vigorous advantages, has emerged as a promising tool for the treatment of ischemic stroke. The mechanisms involve new neural cells and neuronal circuitry formation, antioxidation, inflammation alleviation, angiogenesis, and neurogenesis promotion. In the past decades, in-depth studies have suggested that cell therapy could promote vascular stabilization and decrease blood-brain barrier (BBB) leakage after ischemic stroke. However, the effects and underlying mechanisms on BBB integrity induced by the engrafted cells in ischemic stroke have not been reviewed yet. Herein, we will update the progress in research on the effects of cell therapy on BBB integrity after ischemic stroke and review the underlying mechanisms. First, we will present an overview of BBB dysfunction under the ischemic condition and cells engraftment for ischemic treatment. Then, we will summarize and discuss the current knowledge about the effects and underlying mechanisms of cell therapy on BBB integrity after ischemic stroke. In particular, we will review the most recent studies in regard to the relationship between cell therapy and BBB in tissue plasminogen activator (t-PA)-mediated therapy and diabetic stroke.

Regulation of blood-brain barrier integrity by microglia in health and disease: A therapeutic opportunity

The blood-brain barrier (BBB) is a critical regulator of CNS homeostasis. It possesses physical and biochemical characteristics (i.e. tight junction protein complexes, transporters) that are necessary for the BBB to perform this physiological role. Microvascular endothelial cells require support from astrocytes, pericytes, microglia, neurons, and constituents of the extracellular matrix. This intricate relationship implies the existence of a neurovascular unit (NVU). NVU cellular components can be activated in disease and contribute to dynamic remodeling of the BBB. This is especially true of microglia, the resident immune cells of the brain, which polarize into distinct proinflammatory (M1) or anti-inflammatory (M2) phenotypes. Current data indicate that M1 pro-inflammatory microglia contribute to BBB dysfunction and vascular "leak", while M2 anti-inflammatory microglia play a protective role at the BBB. Understanding biological mechanisms involved in microglia activation provides a unique opportunity to develop novel treatment approaches for neurological diseases. In this review, we highlight characteristics of M1 proinflammatory and M2 anti-inflammatory microglia and describe how these distinct phenotypes modulate BBB physiology. Additionally, we outline the role of other NVU cell types in regulating microglial activation and highlight how microglia can be targeted for treatment of disease with a focus on ischemic stroke and Alzheimer's disease.

Scutellaria baicalensis Flavones as Potent Drugs against Acute Respiratory Injury during SARS-CoV-2 Infection: Structural Biology Approaches

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can result in severe damage to the respiratory system. With no specific treatment to date, it is crucial to identify potent inhibitors of SARS-CoV-2 Chymotrypsin-like protease (3CLpro) that could also modulate the enzymes involved in the respiratory damage that accompanies SARS-CoV-2 infection. Here, flavones isolated from Scutellaria baicalensis (baicalein, baicalin, wogonin, norwogonin, and oroxylin A) were studied as possible compounds in the treatment of SARS-CoV-2 and SARS-CoV-2-induced acute lung injuries. We used structural bioinformatics and cheminformatics to (i) identify the critical molecular features of flavones for their binding activity at human and SARS-CoV-2 enzymes; (ii) predict their drug-likeness and lead-likeness features; (iii) calculate their pharmacokinetic profile, with an emphasis on toxicology; (iv) predict their pharmacodynamic profiles, with the identification of their human body targets involved in the respiratory system injuries; and (v) dock the ligands to SARS-CoV-2 3CLpro. All flavones presented appropriate drug-like and kinetics features, except for baicalin. Flavones could bind to SARS-CoV-2 3CLpro at a similar site, but interact slightly differently with the protease. Flavones’ pharmacodynamic profiles predict that (i) wogonin strongly binds at the cyclooxygenase2 and nitric oxide synthase; (ii) baicalein and norwogonin could modulate lysine-specific demethylase 4D-like and arachidonate 15-lipoxygenase; and (iii) baicalein, wogonin, norwogonin, and oroxylin A bind to SARS-CoV-2 3CLpro. Our results propose these flavones as possible potent drugs against respiratory damage that occurs during SARS-CoV-2 infections, with a strong recommendation for baicalein.

Early Electroacupuncture Extends the rtPA Time Window to 6 h in a Male Rat Model of Embolic Stroke via the ERK1/2-MMP9 Pathway

Background. Recombinant tissue plasminogen activator (rtPA) is the only recommended pharmacological treatment for acute ischemic stroke, but it has a restricted therapeutic time window. When administered at time points greater than 4.5 h after stroke onset, rtPA disrupts the blood-brain barrier (BBB), which leads to serious brain edema and hemorrhagic transformation. Electroacupuncture (EA) exerts a neuroprotective effect on cerebral ischemia; however, researchers have not clearly determined whether EA increases the safety of thrombolysis and extends the therapeutic time window of rtPA administration following ischemic stroke. Objective. The present study was conducted to test the hypothesis that EA extends the therapeutic time window of rtPA for ischemic stroke in a male rat model of embolic stroke. Methods. SD rats were randomly divided into the sham operation group, model group, rtPA group, EA+rtPA group, and rtPA+MEK1/2 inhibitor group. An injection of rtPA was administered 6 h after ischemia. Rats were treated with EA at the Shuigou (GV26) and Neiguan (PC6) acupoints at 2 h after ischemia. Neurological function, infarct volume, BBB permeability, brain edema, and hemorrhagic transformation were assessed at 24 h after ischemia. Western blotting and immunofluorescence staining were performed to detect the levels of proteins involved in the ERK1/2 signaling pathway (MEK1/2 and ERK1/2), tight junction proteins (Claudin5 and ZO-1), and MMP9 in the ischemic penumbra at 24 h after stroke. Results. Delayed rtPA treatment aggravated hemorrhagic transformation and brain edema. However, treatment with EA plus rtPA significantly improved neurological function and reduced the infarct volume, hemorrhagic transformation, brain edema, and EB leakage in rats compared with rtPA alone. EA increased the levels of tight junction proteins, inhibited the activation of the ERK1/2 signaling pathway, and reduced MMP9 overexpression induced by delayed rtPA thrombolysis. Conclusions. EA potentially represents an effective adjunct method to increase the safety of thrombolytic therapy and extend the therapeutic time window of rtPA administration following ischemic stroke. This neuroprotective effect may be mediated by the inhibition of the ERK1/2-MMP9 pathway and alleviation of the destruction of the BBB.

Nose-to-brain Delivery of Natural Compounds for the Treatment of Central Nervous System Disorders

BACKGROUND

Several natural compounds have demonstrated potential for the treatment of central nervous system disorders such as ischemic cerebrovascular disease, glioblastoma, neuropathic pain, neurodegenerative diseases, multiple sclerosis and migraine. This is due to their well-known antioxidant, anti-inflammatory, neuroprotective, anti-tumor, anti-ischemic and analgesic properties. Nevertheless, many of these molecules have poor aqueous solubility, low bioavailability and extensive gastrointestinal and/or hepatic first-pass metabolism, leading to a quick elimination as well as low serum and tissue concentrations. Thus, the intranasal route emerged as a viable alternative to oral or parenteral administration, by enabling a direct transport into the brain through the olfactory and trigeminal nerves. With this approach, the blood-brain barrier is circumvented and peripheral exposure is reduced, thereby minimizing possible adverse effects.

OBJECTIVE

Herein, brain-targeting strategies for nose-to-brain delivery of natural compounds, including flavonoids, cannabinoids, essential oils and terpenes, will be reviewed and discussed. Brain and plasma pharmacokinetics of these molecules will be analyzed and related to their physicochemical characteristics and formulation properties.

CONCLUSION

Natural compounds constitute relevant alternatives for the treatment of brain diseases but often require loading into nanocarrier systems to reach the central nervous system in sufficient concentrations. Future challenges lie in a deeper characterization of their therapeutic mechanisms and in the development of effective, safe and brain-targeted delivery systems for their intranasal administration.

Diabetes Mellitus/Poststroke Hyperglycemia: a Detrimental Factor for tPA Thrombolytic Stroke Therapy

Intravenous administration of tissue-type plasminogen activator (IV tPA) therapy has long been considered a mainstay in ischemic stroke management. However, patients respond to IV tPA therapy unequally with some subsets of patients having worsened outcomes after treatment. In particular, diabetes mellitus (DM) is recognized as a clinically important vascular comorbidity that leads to lower recanalization rates and increased risks of hemorrhagic transformation (HT). In this short-review, we summarize the recent advances in understanding of the underlying mechanisms involved in post-IV tPA worsening of outcome in diabetic stroke. Potential pathologic factors that are related to the suboptimal tPA recanalization in diabetic stroke include higher plasma plasminogen activator inhibitor (PAI)-1 level, diabetic atherogenic vascular damage, glycation of the tPA receptor annexin A2, and alterations in fibrin clot density. While factors contributing to the exacerbation of HT in diabetic stroke include hyperglycemia, vascular oxidative stress, and inflammation, tPA neurovascular toxicity and imbalance in extracellular proteolysis are discussed. Besides, impaired collaterals in DM also compromise the efficacy of IV tPA therapy. Additionally, several tPA combination approaches developed from experimental studies that may help to optimize IV tPA therapy are also briefly summarized. In summary, more research efforts are needed to improve the safety and efficacy of IV tPA therapy in ischemic stroke patients with DM/poststroke hyperglycemia.

Osteopontin as a candidate of therapeutic application for the acute brain injury

Acute brain injury is the leading cause of human death and disability worldwide, which includes intracerebral haemorrhage, subarachnoid haemorrhage, cerebral ischaemia, traumatic brain injury and hypoxia‐ischaemia brain injury. Currently, clinical treatments for neurological dysfunction of acute brain injury have not been satisfactory. Osteopontin (OPN) is a complex adhesion protein and cytokine that interacts with multiple receptors including integrins and CD44 variants, exhibiting mostly neuroprotective roles and showing therapeutic potential for acute brain injury. OPN‐induced tissue remodelling and functional repair mainly rely on its positive roles in the coordination of pro‐inflammatory and anti‐inflammatory responses, blood‐brain barrier maintenance and anti‐apoptotic actions, as well as other mechanisms such as affecting the chemotaxis and proliferation of nerve cells. The blood OPN strongly parallel with the OPN induced in the brain and can be used as a novel biomarker of the susceptibility, severity and outcome of acute brain injury. In the present review, we summarized the molecular signalling mechanisms of OPN as well as its overall role in different kinds of acute brain injury.

Combined Treatment With 2-(2-Benzofu-Ranyl)-2-Imidazoline and Recombinant Tissue Plasminogen Activator Protects Blood-Brain Barrier Integrity in a Rat Model of Embolic Middle Cerebral Artery Occlusion

Recombinant tissue plasminogen activator (rt-PA) is used to treat acute ischemic stroke but is only effective if administered within 4.5 h after stroke onset. Delayed rt-PA treatment causes blood-brain barrier (BBB) disruption and hemorrhagic transformation. The compound 2-(-2-benzofuranyl)-2-imidazoline (2-BFI), a newly discovered antagonist of high-affinity postsynaptic N-methyl-D-aspartate (NMDA) receptors, has been shown to have neuroprotective effects in ischemia. Here, we investigated whether combining 2-BFI and rt-PA can ameliorate BBB disruption and prolong the therapeutic window in a rat model of embolic middle cerebral artery occlusion (eMCAO). Ischemia was induced in male Sprague Dawley rats by eMCAO, after which they were treated with 2-BFI (3 mg/kg) at 0.5 h in combination with rt-PA (10 mg/kg) at 6 or 8 h. Control rats were treated with saline or 2-BFI or rt-PA. Combined therapy with 2-BFI and rt-PA (6 h) reduced the infarct volume, denatured cell index, BBB permeability, and brain edema. This was associated with increased expression of aquaporin 4 (AQP4) and tight junction proteins (occludin and ZO-1) and downregulation of intercellular adhesion molecule 1 (ICAM-1) and matrix metalloproteinases 2 and 9 (MMP2 and MMP9). We conclude that 2-BFI protects the BBB from damage caused by delayed rt-PA treatment in ischemia. 2-BFI may therefore extend the therapeutic window up to 6 h after stroke onset in rats and may be a promising therapeutic strategy for humans. However, mechanisms to explain the effects oberved in the present study are not yet elucidated.

Persistent Neurovascular Unit Dysfunction: Pathophysiological Substrate and Trigger for Late-Onset Neurodegeneration After Traumatic Brain Injury

Traumatic brain injury (TBI) represents one of the major causes of death worldwide and leads to persisting neurological deficits in many of the survivors. One of the most significant long-term sequelae deriving from TBI is neurodegenerative disease, which is a group of incurable diseases that impose a heavy socio-economic burden. However, mechanisms underlying the increased susceptibility of TBI to neurodegenerative disease remain elusive. The neurovascular unit (NVU) is a functional unit composed of neurons, neuroglia, vascular cells, and the basal lamina matrix. The key role of NVU dysfunction in many central nervous system diseases has been revealed. Studies have proved the presence of prolonged structural and functional abnormalities of the NVU after TBI. Moreover, growing evidence suggests impaired NVU function is also implicated in neurodegenerative diseases. Therefore, we propose the Neurovascular Unit Dysfunction (NVUD) Hypothesis, in which the persistent NVU dysfunction is thought to underlie the development of post-TBI neurodegeneration. We deduce NVUD Hypothesis through relational inference and supporting evidence, and suggest continued NVU abnormalities following TBI serve as the pathophysiological substrate and trigger yielding chronic neuroinflammation, proteinopathies and oxidative stress, consequently leading to the progression of neurodegenerative diseases. The NVUD Hypothesis may provide potential treatment and prevention strategies for TBI and late-onset neurodegenerative diseases.

Targeting Myeloperoxidase (MPO) Mediated Oxidative Stress and Inflammation for Reducing Brain Ischemia Injury: Potential Application of Natural Compounds

Oxidative stress and inflammation are two critical pathological processes of cerebral ischemia-reperfusion injury. Myeloperoxidase (MPO) is a critical inflammatory enzyme and therapeutic target triggering both oxidative stress and neuroinflammation in the pathological process of cerebral ischemia-reperfusion injury. MPO is presented in infiltrated neutrophils, activated microglial cells, neurons, and astrocytes in the ischemic brain. Activation of MPO can catalyze the reaction of chloride and H2O2 to produce HOCl. MPO also mediates oxidative stress by promoting the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), modulating the polarization and inflammation-related signaling pathways in microglia and neutrophils. MPO can be a therapeutic target for attenuating oxidative damage and neuroinflammation in ischemic stroke. Targeting MPO with inhibitors or gene deficiency significantly reduced brain infarction and improved neurological outcomes. This article discusses the important roles of MPO in mediating oxidative stress and neuroinflammation during cerebral ischemia-reperfusion injury and reviews the current understanding of the underlying mechanisms. Furthermore, we summarize the active compounds from medicinal herbs with potential as MPO inhibitors for anti-oxidative stress and anti-inflammation to attenuate cerebral ischemia-reperfusion injury, and as adjunct therapeutic agents for extending the window of thrombolytic treatment. We highlight that targeting MPO could be a promising strategy for alleviating ischemic brain injury, which merits further translational study.