An MMP-9 exclusive neutralizing antibody attenuates blood-brain barrier breakdown in mice with stroke and reduces stroke patient-derived MMP-9 activity

Research progress of active compounds from traditional Chinese medicine in the treatment of stroke

Stroke is a serious cerebrovascular disease that is categorized into two types: ischemic and hemorrhagic. The pathological mechanisms of ischemic stroke are complex and diverse, encompassing processes such as neuroinflammation and apoptosis. The pathological processes of hemorrhagic stroke primarily involve the disruption of the blood-brain barrier and cerebral edema. Western medical treatment methods show certain effectiveness during the acute phase of stroke, but they are limited by a narrow therapeutic window and secondary injuries. Traditional Chinese medicine (TCM) has a long history and unique advantages in treating stroke. Studies confirm that active compounds derived from TCM exert multi-pathway, multi-target effects, significantly improving therapeutic outcomes and reducing adverse reactions. However, due to the complexity of the components in TCM, research on monomeric components still faces challenges. This article reviews the relevant research progress published in domestic and international journals over the past twenty years regarding the mechanisms of action of monomeric components of TCM in the treatment of stroke, aiming to provide insights and references for the clinical application of TCM in stroke treatment and further new drug development.

Matrix metalloproteinase-9 (MMP-9): A macromolecular mediator in CNS infections: A review

Matrix metalloproteinase-9 (MMP-9) is a macromolecular zinc-dependent endopeptidase that plays a critical role in the pathogenesis of Central Nervous System (CNS) infections by modulating extracellular matrix remodelling and blood-brain barrier (BBB) dynamics. This review elucidates the structural and functional properties of MMP-9, highlighting its distinct domain architecture that enables substrate specificity and regulatory mechanisms. MMP-9-mediated BBB disruption is a hallmark of bacterial, viral, fungal, and parasitic CNS infections, facilitating immune cell infiltration and pathogen entry while exacerbating neuroinflammation and tissue damage. Elevated MMP-9 levels in cerebrospinal fluid (CSF) correlate with disease severity, suggesting its potential as a diagnostic biomarker. Advances in therapeutic strategies targeting MMP-9, including small molecule inhibitors, monoclonal antibodies, and peptide-based therapies, demonstrate promising results in mitigating BBB disruption and neuroinflammation. This comprehensive review underscores the dual role of MMP-9 as both a biomarker and therapeutic target, advocating for its inclusion in adjunctive treatment regimens to improve outcomes in CNS infections. Future research should focus on refining MMP-9 inhibitors for clinical use, ensuring specificity, and minimizing off-target effects to harness its full therapeutic potential.

Sulfated chitosan directs the recovery of ischemic stroke by attenuating the inflammatory cascade

Background: Ischemic stroke is considered a fatal ischemic disease with high mortality and morbidity. Acute ischemic stroke is a cascade of inflammatory reactions, which not only causes vascular degeneration but also leads to neurological disorders. During this period, the rapid response of neutrophil-dominated granulocytes releases cytokines and chemokines to affect tissue repair. Thus, effective regulation of neutrophils appears to be the key in treating major organ injuries associated with inflammation. Methods: This study developed a semisynthetic sulfated chitosan (SCS) associated with the functional sulfated groups. The immunoregulatory effects of SCS on neutrophils were tested by Real-Time Quantitative Reverse Transcription (RT-PCR), ELISA and immunofluorescence staining at gene and protein levels in vitro. Flow cytometry, WB and PCR were used to study the effect of neutrophils on macrophages, indicating the regulation of the inflammatory cascade by SCS. Acute ischemic stroke model was established to verify the effectiveness and the regulation of inflammatory cascade of SCS. Finally, the lower limb ischemia model was used to verify the universality of SCS in the treatment of ischemic diseases, especially with regard to acute inflammatory-related major organ damage. Results: SCS can not only promote neutrophil apoptosis, but also enable neutrophils to produce vascular-related subsets to regulate immunity and promote angiogenesis. Neutrophil stimulated by SCS mediated macrophage polarization via IL-10-induced Stat3 signaling pathway to weaken the inflammatory cascade. In animal models of ischemic hind limb and ischemic stroke, SCS had demonstrated its ability to shorten the acute inflammatory period, as indicated by neutrophil, and accelerate the subsequent repair period characterized by the presence of M2 macrophages. Additionally, SCS effectively inhibits the expression of MMP-9 to provide a favorable environment for rapid extracellular matrix reconstruction. Encouragingly, treatment with SCS had been shown to reduce the expansion of the infarct volume by approximately 20% in our experiments. Conclusion: This study underscores the effect of SCS in regulating the heterogeneity of neutrophils in order to suppress the initiation of inflammation to treat ischemic stroke. Crucially, our approach relies on non-exogenous growth factors and cells, highlighting its remarkable potential for clinical translatability in the treatment of major organ injuries.

Neurotrophic factor biomarkers for ischemic stroke diagnosis and mechanistic insights

Ischemic stroke (IS), a multifactorial disease resulting from the complex interplay of various environmental and genetic risk factors. Neurotrophic factors (NTFs) have a potential role in IS, but the exact mechanisms are unknown. The aim of this study was to identify biomarkers associated with the occurrence and development of NTFs and to analyze their potential mechanisms of action. In this study, we selected the intersection of neurotrophic factor genes, differentially expressed genes (DEGs) and key genes in the IS module based on IS-related datasets (GSE16561 and GSE58294). Machine learning screened out 5 biomarkers for IS diagnosis (MMP9, MARCKS, IGF2R, HECW2 and CYBRD1). GSEA results showed that different signaling pathways were activated in IS samples with high expression of different diagnostic genes. Furthermore, an immunological analysis was carried out, which demonstrated significant differences in the levels of activated B cells, neutrophils, and activated CD8 T cells between IS patients and normal samples. RT-qPCR results showed that there were significant differences in the expression of CYBRD1, MARCKS and MMP9 between IS and control patients. In conclusion, we identified 5 diagnostic markers that may be involved in the progression of IS, including MMP9, MARCKS, IGF2R, HECW2 and CYBRD1. Finally, differential expression of MMP9, MARCKS, and CYBRD1 was detected in peripheral blood samples from 15 IS and 5 normal cases. Our analysis could serve as a foundation for enhancing comprehension of the underlying molecular mechanisms governing the pathogenesis and progression of IS. The identified biomarkers might serve as targets for the development of novel diagnostic assays, enabling earlier detection of IS and potentially leading to more timely and effective treatment interventions.

Crosstalk Between Matrix Metalloproteinases and Their Inducer EMMPRIN/CD147: a Promising Therapeutic Target for Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is characterized by the disruption of cerebrovascular integrity, resulting in hematoma enlargement, edema formation, and physical damage in the brain parenchyma. Primary ICH also leads to secondary brain injury contributed by oxidative stress, dysregulated immune responses, and proteolysis. In this context, matrix metalloproteinases (MMPs) represent a ubiquitous superfamily of structurally related zinc-dependent endopeptidases capable of degrading all components of the extracellular matrix. They disrupt the blood-brain barrier and promote neuroinflammation. Importantly, several MMP members are upregulated following ICH, and members may have different functions at specific periods in ICH. Hence, the modulation and function of MMPs are more complex than expected. Extracellular matrix metalloproteinase inducer (EMMPRIN, CD147) is a transmembrane glycoprotein that induces the production of MMPs. In this review, we systematically discuss the biology and functions of MMPs and EMMPRIN/CD147 in ICH and the complex crosstalk between them.

MMP-9 inhibitor SB-3CT improves neurological outcomes in ischemic stroke mice by modulation of astrocytic lipid metabolism

The acute phase of ischemic stroke is marked by a surge in matrix metalloproteinase-9 (MMP-9) activity. While integral to natural repair processes, MMP-9 exacerbates injury by breaking down the blood-brain barrier (BBB) and promoting edema and inflammation. MMP-9 is predominantly secreted by inflammatory cells such as neutrophils, macrophages and microglia soon after stroke onset. In this study we investigated the effects of MMP-9 inhibition via SB-3CT on astrocytic lipid metabolism, and its potential to enhance neuronal survival and recovery following ischemic stroke. Mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 60 min, mice then were injected with SB-3CT (25 mg/kg, i.v.). On D3 post tMCAO, neurological outcomes were assessed, and whole brains were collected for analysis. Lipidomic analysis of brain tissue showed that SB-3CT treatment significantly restrained astrocytic cholesterol metabolism by modulating the sphingolipid and glycerophospholipid pathways. Specifically, SB-3CT reduced ceramide accumulation and promoted an increase in neuroprotective hexosylceramides, leading to enhanced neuronal survival and synaptic integrity. In addition, SB-3CT treatment reduced astrocytic and microglial reactivity, thereby mitigating neuroinflammation. In order to optimize the timing and dosage of MMP-9 inhibition to maximize the therapeutic efficacy, tMCAO mice were given three injections of SB-3CT on D0, D2 and D4 within 7 days after modeling. We found that prolonged MMP-9 inhibition alleviated astrogliosis, concurrently impaired neurological recovery and inhibited angiogenesis. These results demonstrate the critical role of lipid metabolism in MMP-9-mediated brain injury and the potential of SB-3CT as a therapeutic strategy for ischemic stroke by targeting astrocytic lipid metabolism.

Persisting blood-brain barrier disruption following cisplatin treatment in a mouse model of chemotherapy-associated cognitive impairment

Chemotherapy-related cognitive impairment, commonly referred to as "chemobrain," significantly affects cancer survivors' quality of life, yet its underlying mechanisms remain unclear. Most chemotherapeutic agents cannot cross the blood-brain barrier (BBB), yet they cause central nervous system side effects, suggesting alternative pathways of toxicity. Given that these drugs interact with the cerebrovascular endothelium at their highest concentrations, it is logical to hypothesize that endothelial damage contributes to these effects. Our recent studies demonstrated that paclitaxel-induced cognitive impairment in a mouse model results in a partial BBB disruption and subsequent neuroinflammation, mediated by chemotherapy-induced endothelial senescence. In this pilot study, we used two-photon microscopy to assess BBB permeability in mice receiving a clinically relevant cisplatin regimen, evaluating the leakage of fluorescent dextran tracers of varying molecular weights. Two months post-treatment, cisplatin-treated mice exhibited significantly increased BBB permeability to smaller molecular tracers (40 kDa, 3 kDa, and 0.3 kDa) compared to controls, indicating sustained BBB disruption. These results align with our findings for paclitaxel and suggest that chemotherapy-induced endothelial damage and senescence play a central role in cognitive impairments. Interventions targeting endothelial health could mitigate these long-term effects, improving cognitive outcomes for cancer survivors.

Human-induced pluripotent stem cell-derived neural stem cell exosomes improve blood-brain barrier function after intracerebral hemorrhage by activating astrocytes via PI3K/AKT/MCP-1 axis

JOURNAL/nrgr/04.03/01300535-202502000-00029/figure1/v/2024-05-28T214302Z/r/image-tiff Cerebral edema caused by blood-brain barrier injury after intracerebral hemorrhage is an important factor leading to poor prognosis. Human-induced pluripotent stem cell-derived neural stem cell exosomes (hiPSC-NSC-Exos) have shown potential for brain injury repair in central nervous system diseases. In this study, we explored the impact of hiPSC-NSC-Exos on blood-brain barrier preservation and the underlying mechanism. Our results indicated that intranasal delivery of hiPSC-NSC-Exos mitigated neurological deficits, enhanced blood-brain barrier integrity, and reduced leukocyte infiltration in a mouse model of intracerebral hemorrhage. Additionally, hiPSC-NSC-Exos decreased immune cell infiltration, activated astrocytes, and decreased the secretion of inflammatory cytokines like monocyte chemoattractant protein-1, macrophage inflammatory protein-1α, and tumor necrosis factor-α post-intracerebral hemorrhage, thereby improving the inflammatory microenvironment. RNA sequencing indicated that hiPSC-NSC-Exo activated the PI3K/AKT signaling pathway in astrocytes and decreased monocyte chemoattractant protein-1 secretion, thereby improving blood-brain barrier integrity. Treatment with the PI3K/AKT inhibitor LY294002 or the monocyte chemoattractant protein-1 neutralizing agent C1142 abolished these effects. In summary, our findings suggest that hiPSC-NSC-Exos maintains blood-brain barrier integrity, in part by downregulating monocyte chemoattractant protein-1 secretion through activation of the PI3K/AKT signaling pathway in astrocytes.

Advances in the Study of Necroptosis in Vascular Dementia: Focus on Blood-Brain Barrier and Neuroinflammation

BACKGROUND

Vascular dementia (VaD) includes a group of brain disorders that are characterized by cerebrovascular pathology.Neuroinflammation, disruption of the blood-brain barrier (BBB) permeability, white matter lesions, and neuronal loss are all significant pathological manifestations of VaD and play a key role in disease progression. Necroptosis, also known asprogrammed necrosis, is a mode of programmed cell death distinct from apoptosis and is closely associated with ischemic injury and neurodegenerative diseases. Recent studies have shown that necroptosis in VaD exacerbates BBB destruction, activates neuroinflammation, promotes neuronal loss, and severely affects VaD prognosis.

RESULTS AND CONCLUSIONS

In this review, we outline the significant roles of necroptosis and its molecular mechanisms in the pathological process of VaD, with a particular focus on the role of necroptosis in modulating neuroinflammation and exacerbating the disruption of BBB permeability in VaD, and elaborate on the molecular regulatory mechanisms and the centrally involved cells of necroptosis mediated by tumor necrosis factor-α in neuroinflammation in VaD. We also analyze the possibility and specific strategy that targeting necroptosis would help inhibit neuroinflammation and BBB destruction in VaD. With a focus on necroptosis, this study delved into its impact on the pathological changes and prognosis of VaD to provide new treatment ideas.

Inhibition of matrix metalloproteinases to reduce blood brain barrier disruption and haemorrhagic transformation in ischaemic stroke: Go broad or go narrow?

Ischaemic stroke characterises impulsive cerebral-region hypoxia due to deep intracerebral arteriole blockage, often accompanied by permanent cerebral infarction and cognitive impairment. Thrombolysis with recombinant tissue plasminogen activator (rtPA) and thrombectomy remain the only guidance-approved therapies. However, emerging data draws clear links between such therapies and haemorrhage transformation, which occur when cerebral vasculature is damaged during ischaemia/reperfusion. Studies have shown that matrix metalloproteinases (MMPs) play a significant role in haemorrhage transformation, by depleting the extracellular matrix (ECM) and disrupting the blood brain barrier (BBB). Inhibitors of MMPs may be used to prevent ischaemic stroke patients from BBB disruption and haemorrhage transformation, particularly for those receiving rtPA treatment. Preclinical studies found that inhibition of MMPs with agents or in knock out mice, effectively reduced BBB disruption and infarct volume, leading to improved ischaemic stroke outcomes. At present, MMP inhibition is not an approved therapy for stroke patients. There remain concerns about timing, dosing, duration of MMP inhibition and selection of either broad spectrum or specific MMP inhibitors for stroke patients. This review aims to summarize current knowledge on MMP inhibition in ischaemic stroke and explore whether a broad spectrum or a specific MMP inhibitor should be used for ischaemic stroke patient treatment. It is crucial to inhibit MMP activities early and sufficiently to ensure BBB intact during ischaemia and reperfusion, but also to reduce side effects of MMP inhibitors to minimum. Recent advance in stroke therapy by thrombectomy could aid in such treatment with intra-arterially delivery of MMP inhibitors (and/or antioxidants).

Single-cell RNA sequencing reveals S100A8/A9hi neutrophils-induced endothelial cell death and lymphocyte infiltration after ischemic stroke

Stroke is a major global cause of death and disability, with ischemic stroke being the most common type. The disruption of the blood-brain barrier (BBB) is a key factor in the pathophysiology of ischemic stroke, allowing immune cells to infiltrate and worsening neuroinflammation. This study uses single-cell RNA sequencing (scRNA-seq) to examine the transcriptional changes in neutrophils, endothelial cells, and T cells during ischemic stroke. Our findings indicate a significant increase in neutrophil and lymphocyte infiltration, along with a notable decrease in endothelial cell populations, demonstrating severe BBB disruption. Differential gene expression analysis shows that endothelial cells lose important characteristics post-stroke, while lymphocytes activate cytotoxic pathways that may lead to neuronal damage. Additionally, we reveal the contrasting roles of CXCR2 and CXCR4 in neutrophil movement and identify neutrophil-derived damage-associated molecular patterns (DAMPs) and matrix metalloproteinases (MMPs) as key drivers of endothelial cell apoptosis. Notably, the S100A8/A9 inhibitor paquinimod significantly protects neurons and reduces lymphocyte infiltration, suggesting that targeting S100A8/A9 could be a promising therapeutic strategy for reducing neurological deficits after ischemic stroke. Overall, these results enhance our understanding of the complex interactions between immune cells and the BBB in ischemic stroke, paving the way for innovative therapeutic approaches aimed at maintaining brain integrity and improving patient outcomes.

Neutrophil Extracellular Traps Induce Brain Edema Around Intracerebral Hematoma via ERK-Mediated Regulation of MMP9 and AQP4

Perihematomal edema (PHE) significantly aggravates secondary brain injury in patients with intracerebral hemorrhage (ICH), yet its detailed mechanisms remain elusive. Neutrophil extracellular traps (NETs) are known to exacerbate neurological deficits and worsen outcomes after stroke. This study explores the potential role of NETs in the pathogenesis of brain edema following ICH. The rat ICH model was created, immunofluorescence and Western blot were used to examine neutrophil accumulation, NET markers citrullinated histone H3 (CitH3) and myeloperoxidase (MPO), tight junction proteins (ZO-1 and Occludin), Aquaporin-4 (AQP4), matrix metalloproteinase-9 (MMP-9), and ERK phosphorylation (p-ERK) in brain tissues surrounding the hematoma. TUNEL staining and behavioral tests were employed to evaluate neuronal apoptosis and neurological dysfunction, while blood-brain barrier (BBB) permeability and brain edema were also measured by Evans blue and brain water content. Furthermore, the molecular mechanisms related to NETs-induced PHE were investigated using NETs, ERK, MMP-9 and AQP4 regulators, respectively. Ly6G+ neutrophils surrounding the hematoma developed NETs within 3 days post-ICH. NETs decreased tight junction proteins, destroyed BBB integrity, promoted brain edema, increased neuronal apoptosis, and exacerbated neurological deficits. Conversely, inhibition of NETs mitigated PHE, reduced neuronal apoptosis, and improved neurological functions. Mechanistically, NET-induced PHE was originated from impairment of BBB tight junction via ERK/MMP9 pathway, coupled with ERK-mediated AQP4 downregulation in perihematomal regions. These findings elucidated the effects of NETs on PHE, which offered promising insights for targeting NETs to relieve brain edema and secondary brain injury post-ICH.

Snake venom weakens neurovascular integrity and promotes vulnerability to neuroinflammation

Snake envenomation poses significant medical challenges, particularly in subtropical and tropical regions, with long-term impacts on neurovascular integrity and neuroinflammation remaining underexplored. This study investigates the effects of venom from four species of venomous snakes in southern China-Zhoushan Cobra (Naja atra, NA), Many-banded Krait (Bungarus multicinctus, BM), Five-paced Pit Viper (Deinagkistrodon acutus, DA), and Chinese Moccasin (Protobothrops mucrosquamatus, PM) - on the blood-brain barrier (BBB) and chronic neuroinflammation. Using mass spectrometry, we analyzed venom protein compositions, while cytotoxic effects on mouse brain endothelial cells (bEND.3) were evaluated to determine IC50 values. In vitro BBB models and in vivo experiments in C57BL/6J mice revealed that NA venom, in particular, significantly compromised BBB integrity without inducing large-scale apoptosis, leading to persistent BBB disruption characterized by increased permeability and selective degradation of extracellular matrix and tight junction proteins. Moreover, to simulate secondary infections that often occur following snakebites, we combined venom exposure with lipopolysaccharide (LPS) treatment, which exacerbated neuroinflammatory responses by intensifying microglial activation and promoting a pro-inflammatory phenotype. These findings highlight the role of snake venom in compromising neurovascular integrity and promoting vulnerability to chronic neuroinflammation, emphasizing the need for further research into venom-induced neuroinflammatory pathways and their potential as therapeutic targets.

Sphk1/S1P pathway promotes blood-brain barrier breakdown after intracerebral hemorrhage through inducing Nlrp3-mediated endothelial cell pyroptosis

Intracerebral hemorrhage (ICH) is a severe stroke subtype with high mortality and limited therapeutic options. The blood-brain barrier (BBB) breakdown post-ICH exacerbates secondary brain injury, highlighting the need for targeted therapies to preserve the BBB integrity. We aim to investigate the role of the Sphk1/S1P pathway in BBB breakdown following ICH and to evaluate the therapeutic potential of Sphk1 inhibition in mitigating this breakdown. Using a combination of human patient samples, mouse models of ICH, and in vitro cellular assays, we assessed the expression levels of Sphk1/S1P after ICH and changes of the BBB after ICH. The Sphk1 inhibitor PF543 and siRNAs were utilized to explore the pathway's impact on BBB integrity and the underlying mechanisms. The results indicate significant upregulation of Sphk1/S1P in the peri-hematomal brain tissue after ICH, which correlates with increased BBB leakage. Pharmacological inhibition of Sphk1 with PF543 attenuates BBB leakage, reduces hematoma volume, and improves neurological outcomes in mice. At the molecular and ultrastructural level, Sphk1 inhibition protects the BBB integrity by preserving tight junction proteins and suppressing endothelial transcytosis. Furthermore, mechanistic studies reveal that Sphk1 promotes Nlrp3-mediated pyroptosis of brain endothelial cells through the ERK1/2 signaling pathway. Taken together, the Sphk1/S1P pathway plays a critical role in ICH-induced BBB breakdown, and its inhibition represents a promising therapeutic strategy for ICH management.

Basement membranes' role in immune cell recruitment to the central nervous system

Basement membranes form part of the extracellular matrix (ECM), which is the structural basis for all tissue. Basement membranes are cell-adherent sheets found between cells and vascular endothelia, including those of the central nervous system (CNS). There is exceptional regional specialisation of these structures, both in tissue organisation and regulation of tissue-specific cellular processes. Due to their location, basement membranes perform a key role in immune cell trafficking and therefore are important in inflammatory processes causing or resulting from CNS disease and injury. This review will describe basement membranes in detail, with special focus on the brain. We will cover how genetic changes drive brain pathology, describe basement membranes' role in immune cell recruitment and how they respond to various brain diseases. Understanding how basement membranes form the junction between the immune and central nervous systems will be a major advance in understanding brain disease.

The therapeutic effects of salvianolic acids on ischemic stroke: From molecular mechanisms to clinical applications

Ischemic stroke (IS), primarily caused by cerebrovascular occlusion, poses a significant public health challenge with limited effective therapeutic options. Evidence suggests that salvianolic acids (SAs), mainly from Salvia miltiorrhiza Bunge, have been formulated into injections and are widely used in clinical treatments for cardiovascular and cerebrovascular diseases, including stroke. The pharmacological properties of SAs include reducing neuroinflammation, alleviating oxidative stress injury, inhibiting cellular apoptosis, preserving endothelial function, maintaining blood-brain barrier integrity, and promoting angiogenesis. Salvianolic acids for injection (SAFI) serve as a safe and effective treatment option for cardiovascular and cerebrovascular conditions by influencing various signaling pathways and molecular targets associated with these diseases. In this review, we first discuss the pathogenesis of IS, then summarize the classification of SAs, elaborate detailed molecular mechanisms of their efficacy, and the related clinical applications of SAFI. We also emphasize the recent pharmacological advancements and therapeutic possibilities of this promising drug preparation derived from herbs for cerebrovascular conditions.

Overexpression of endothelial S1pr2 promotes blood-brain barrier disruption via JNK/c-Jun/MMP-9 pathway after traumatic brain injury in both in vivo and in vitro models

Objectives

The disruption of blood-brain barrier (BBB) is associated with poor outcomes of TBI patients. Sphingosine-1-phosphate receptor 2 (S1pr2), a member of the G protein-coupled receptor family, is involved in endothelial activation and the regulation of vascular integrity. We hypothesized that the inhibition of S1pr2 may alleviate BBB disruption and explored potential underlying molecular mechanisms.

Methods

Lesion volumes were assessed utilizing Nissl staining; neurological outcomes were evaluated through a battery of neurobehavioral assessments; phenotype-associated proteins were scrutinized via Western blot analysis; levels of reactive oxygen species (ROS), neuronal apoptosis, and S1pr2 expression were determined using immunofluorescence staining. The impact of S1pr2 inhibition after TBI and its underlying mechanism were elucidated using the selective S1pr2 inhibitor JTE-013, the JNK phosphorylation inhibitor SP600125, and cellular models. Chip-qPCR was employed to further elucidate the binding sites of the transcription factor c-Jun.

Results

The expression of S1pr2 significantly increased following TBI in mice. Pharmacological inhibition of S1pr2 alleviated secondary injury with reduced lesion volume, ROS generation, cerebral oedema, neurological deficits, and neuronal apoptosis; BBB disruption was also mitigated, accompanied by reduced degradation of tight junction proteins and decreased induction of matrix metalloproteinases-9 (MMP-9) post-TBI. Mechanistically, TBI induces an increase in S1pr2 specifically in endothelial cells, leading to the promotion of MMP-9 transactivation by enhancing JNK/c-Jun signaling. This results in the degradation of tight junction proteins and increased BBB permeability. Through in vitro and in vivo Chip-qPCR experiments, we verified that AP-1a and AP-1b of MMP-9 promoter function as binding sites for phosphorylated c-Jun.

Conclusion

Our findings identify a previously undisclosed role of S1pr2 in the pathophysiology of TBI. The S1pr2 inhibition presents a novel approach to alleviate BBB disruption after TBI through regulating the JNK/c-Jun/MMP-9 pathway.

Emerging strategies for nerve repair and regeneration in ischemic stroke: neural stem cell therapy

Ischemic stroke is a major cause of mortality and disability worldwide, with limited treatment options available in clinical practice. The emergence of stem cell therapy has provided new hope to the field of stroke treatment via the restoration of brain neuron function. Exogenous neural stem cells are beneficial not only in cell replacement but also through the bystander effect. Neural stem cells regulate multiple physiological responses, including nerve repair, endogenous regeneration, immune function, and blood-brain barrier permeability, through the secretion of bioactive substances, including extracellular vesicles/exosomes. However, due to the complex microenvironment of ischemic cerebrovascular events and the low survival rate of neural stem cells following transplantation, limitations in the treatment effect remain unresolved. In this paper, we provide a detailed summary of the potential mechanisms of neural stem cell therapy for the treatment of ischemic stroke, review current neural stem cell therapeutic strategies and clinical trial results, and summarize the latest advancements in neural stem cell engineering to improve the survival rate of neural stem cells. We hope that this review could help provide insight into the therapeutic potential of neural stem cells and guide future scientific endeavors on neural stem cells.

Proteomic Characterization of 1000 Human and Murine Neutrophils Freshly Isolated From Blood and Sites of Sterile Inflammation

Neutrophils are indispensable for defense against pathogens. Injured tissue-infiltrated neutrophils can establish a niche of chronic inflammation and promote degeneration. Studies investigated transcriptome of single-infiltrated neutrophils which could misinterpret molecular states of these post mitotic cells. However, neutrophil proteome characterization has been challenging due to low harvests from affected tissues. Here, we present a workflow to obtain proteome of 1000 murine and human tissue-infiltrated neutrophils. We generated spectral libraries containing ∼6200 mouse and ∼5300 human proteins from circulating neutrophils. 4800 mouse and 3400 human proteins were recovered from 1000 cells with 102-108 copies/cell. Neutrophils from stroke-affected mouse brains adapted to the glucose-deprived environment with increased mitochondrial activity and ROS-production, while cells invading inflamed human oral cavities increased phagocytosis and granule release. We provide an extensive protein repository for resting human and mouse neutrophils, identify proteins lost in low input samples, thus enabling the proteomic characterization of limited tissue-infiltrated neutrophils.

Exploring the correlation between innate immune activation of inflammasome and regulation of pyroptosis after intracerebral hemorrhage: From mechanism to treatment

Stroke has emerged as the primary cause of disability and death globally in recent years. Intracerebral hemorrhage (ICH), a particularly severe kind of stroke, is occurring in an increasing number of people. The two main clinical treatments for ICH now in use are conservative pharmaceutical therapy and surgical intervention, both of which have risks and drawbacks. Consequently, it is crucial to look into the pathophysiology of ICH and consider cutting-edge therapeutic approaches. Recent research has revealed that pyroptosis is a newly identified type of cell death distinguished by the break of the cell membrane and the discharge of pro-inflammatory substances through different routes. Following ICH, glial cells experience pyroptosis, which worsens neuroinflammation. Hence, the onset and progression of ICH are strongly linked to pyroptosis, which is facilitated by different inflammasomes. It is essential to conduct a comprehensive investigation of ICH damage processes and uncover new targets for treatment. The impact and function of pyroptosis in ICH, as well as the activation and regulation of inflammasomes and their mediated pyroptosis pathways will be fully discussed in this review.

SCG2 mediates blood-brain barrier dysfunction and schizophrenia-like behaviors after traumatic brain injury

Traumatic brain injury (TBI), which is characterized by acute neurological dysfunction, is also one of the most widely recognized environmental risk factors for various neurological and psychiatric disorders. However, the role of TBI in neurological perturbation and the mechanisms underlying these disorders remain unknown. We evaluated transcriptional changes in cells of the frontal cortex after TBI by exploiting single-cell RNA sequencing (scRNA-Seq). We adopted the gene expression omnibus and scRNA-Seq to identify the mediation by secretogranin II (SCG2) of TBI-induced schizophrenia. Astrocytes are a principal source of SCG2 in the frontal cortex after TBI. Our analysis indicated that SCG2-triggered disruption of the blood-brain barrier (BBB) via the CypA-MMP-9 signaling pathway. Furthermore, astrocytic SCG2 knockout in the frontal cortex reduced BBB damage, mitigated inflammation, and inhibited schizophrenia after TBI. In conclusion, we identified the SCG2-CypA-MMP-9 signaling pathway in reactive astrocytes as a key switch in the protection of the BBB and provided a novel therapeutic avenue for treating psychiatric disorders after TBI.

Esculentoside H reduces the PANoptosis and protects the blood-brain barrier after cerebral ischemia/reperfusion through the TLE1/PI3K/AKT signaling pathway

AIMS

Matrix metalloproteinases 9 (MMP9) plays a role in the destruction of blood-brain barrier (BBB) and cell death after cerebral ischemic/reperfusion (I/R). Esculentoside H (EH) is a saponin found in Phytolacca esculenta. It can block JNK1/2 and NF-κB signal mediated expression of MMP9. In this study, we determined whether EH can protect against cerebral I/R injury by inhibiting MMP9 and elucidated the underlying mechanism.

MAIN METHODS

Male SD rats were used to construct middle cerebral artery occlusion (MCAO) models. We determined the effect of EH on MMP9 inhibition, BBB destruction, neuronal death, PANoptosis, infarct volume, and the protective factor TLE1. Adeno-associated virus (AAV) infection was used to establish TLE1 gene overexpression and knockdown rats, which were used to determine the function. LY294002 was used to determine the role of PI3K/AKT signaling in TLE1 function.

KEY FINDINGS

After EH treatment, MMP9 expression, BBB destruction, neuronal death, and infarct volume decreased. We found that TLE1 expression decreased obviously after cerebral I/R. TLE1-overexpressing rats revealed distinct protective effects to cerebral I/R injury. After treatment with LY294002, the protective effect was inhibited. The curative effect of EH also decreased when TLE1 was knocked down.

SIGNIFICANCE

EH alleviates PANoptosis and protects BBB after cerebral I/R via the TLE1/PI3K/AKT signaling pathway. Our findings reveal a novel strategy and new target for treating cerebral I/R injury.

A2 reactive astrocyte-derived exosomes alleviate cerebral ischemia-reperfusion injury by delivering miR-628

Ischemia and hypoxia activate astrocytes into reactive types A1 and A2, which play roles in damage and protection, respectively. However, the function and mechanism of A1 and A2 astrocyte exosomes are unknown. After astrocyte exosomes were injected into the lateral ventricle, infarct volume, damage to the blood-brain barrier (BBB), apoptosis and the expression of microglia-related proteins were measured. The dual luciferase reporter assay was used to detect the target genes of miR-628, and overexpressing A2-Exos overexpressed and knocked down miR-628 were constructed. qRT-PCR, western blotting and immunofluorescence staining were subsequently performed. A2-Exos obviously reduced the infarct volume, damage to the BBB and apoptosis and promoted M2 microglial polarization. RT-PCR showed that miR-628 was highly expressed in A2-Exos. Dual luciferase reporter assays revealed that NLRP3, S1PR3 and IRF5 are target genes of miR-628. After miR-628 was overexpressed or knocked down, the protective effects of A2-Exos increased or decreased, respectively. A2-Exos reduced pyroptosis and BBB damage and promoted M2 microglial polarization through the inhibition of NLRP3, S1PR3 and IRF5 via the delivery of miR-628. This study explored the mechanism of action of A2-Exos and provided new therapeutic targets and concepts for treating cerebral ischemia.

Targeting post-stroke neuroinflammation with Salvianolic acid A: molecular mechanisms and preclinical evidence

Salvianolic acid A (SalA), a bioactive compound extracted from Salvia miltiorrhiza, has garnered considerable interest for its potential in ameliorating the post-stroke neuroinflammation. This review delineates the possible molecular underpinnings of anti-inflammatory and neuroprotective roles of SalA, offering a comprehensive analysis of its therapeutic efficacy in preclinical studies of ischemic stroke. We explore the intricate interplay between post-stroke neuroinflammation and the modulatory effects of SalA on pro-inflammatory cytokines, inflammatory signaling pathways, the peripheral immune cell infiltration through blood-brain barrier disruption, and endothelial cell function. The pharmacokinetic profiles of SalA in the context of stroke, characterized by enhanced cerebral penetration post-ischemia, makes it particularly suitable as a therapeutic agent. Preliminary clinical findings have demonstrated that salvianolic acids (SA) has a positive impact on cerebral perfusion and neurological deficits in stroke patients, warranting further investigation. This review emphasizes SalA as a potential anti-inflammatory agent for the advancement of innovative therapeutic approaches in the treatment of ischemic stroke.

The role of matrix metalloproteinases in the pathogenetic mechanisms of ischemic stroke

   Modern understanding of the mechanisms of the pathogenesis of ischemic stroke has expanded due to the study of neuroinfl ammation processes, in which matrix metalloproteinases (MMPs) play an important role. This literature review describes the main types of MMPs and provides current data on the pathophysiological role of this group of proteases in acute cerebral ischemia, which have multidirectional eff ects depending on the stage of the disease. Clinical studies assessing the role of MMPs in ischemic stroke are in most cases based on experimental models, and their results are ambiguous, which is determined by the versatility of their actions. MMPs are an important regulator of infl ammatory processes, the permeability of the blood-brain barrier and, as a consequence, cerebral edema. However, the positive eff ect of MMPs in the processes of angiogenesis, neurogenesis and neuroplasticity has been proven. Thus, further study of MMPs is relevant from the point of view of their role in functional recovery after ischemic stroke.

Dementia after Ischemic Stroke, from Molecular Biomarkers to Therapeutic Options

Ischemic stroke is a leading cause of disability worldwide. While much of post-stroke recovery is focused on physical rehabilitation, post-stroke dementia (PSD) is also a significant contributor to poor functional outcomes. Predictive tools to identify stroke survivors at risk for the development of PSD are limited to brief screening cognitive tests. Emerging biochemical, genetic, and neuroimaging biomarkers are being investigated in an effort to unveil better indicators of PSD. Additionally, acetylcholinesterase inhibitors, NMDA receptor antagonists, dopamine receptor agonists, antidepressants, and cognitive rehabilitation are current therapeutic options for PSD. Focusing on the chronic sequelae of stroke that impair neuroplasticity highlights the need for continued investigative trials to better assess functional outcomes in treatments targeted for PSD.

Immune-mediated disruption of the blood-brain barrier after intracerebral hemorrhage: Insights and potential therapeutic targets

AIMS

Intracerebral hemorrhage (ICH) is a condition that arises due to the rupture of cerebral blood vessels, leading to the flow of blood into the brain tissue. One of the pathological alterations that occurs during an acute ICH is an impairment of the blood-brain barrier (BBB), which leads to severe perihematomal edema and an immune response.

DISCUSSION

A complex interplay between the cells of the BBB, for example, pericytes, astrocytes, and brain endothelial cells, with resident and infiltrating immune cells, such as microglia, monocytes, neutrophils, T lymphocytes, and others accounts for both damaging and protective mechanisms at the BBB following ICH. However, the precise immunological influence of BBB disruption has yet to be richly ascertained, especially at various stages of ICH.

CONCLUSION

This review summarizes the changes in different cell types and molecular components of the BBB associated with immune-inflammatory responses during ICH. Furthermore, it highlights promising immunoregulatory therapies to protect the integrity of the BBB after ICH. By offering a comprehensive understanding of the mechanisms behind BBB damage linked to cellular and molecular immunoinflammatory responses after ICH, this article aimed to accelerate the identification of potential therapeutic targets and expedite further translational research.

Anesthesia/surgery activate MMP9 leading to blood-brain barrier disruption, triggering neuroinflammation and POD-like behavior in aged mice

Anesthesia and surgery activate matrix metalloproteinase 9 (MMP9), leading to blood-brain barrier (BBB) disruption and postoperative delirium (POD)-like behavior, especially in the elderly. Aged mice received intraperitoneal injections of either the MMP9 inhibitor SB-3CT, melatonin, or solvent, and underwent laparotomy under 3 % sevoflurane anesthesia(anesthesia/surgery). Behavioral tests were performed 24 h pre- and post-operatively. Serum and cortical tissue levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were measured using ELISA. Levels of PDGFRβ, MMP9, tight junction, Mfsd2a, caveolin-1, synaptophysin, and postsynaptic densin (PSD)-95 proteins in the prefrontal cortex were assayed using Western blotting. BBB permeability was assessed by detecting IgG in the prefrontal cortex and serum S100β levels. Anesthesia/surgery-induced peripheral inflammation activated MMP9, which in turn injured pericytes and tight junctions and increased transcytosis, thereby disrupting the BBB. Impaired BBB allowed the migration of peripheral inflammation into the central nervous system (CNS), thereby inducing neuroinflammation, synaptic dysfunction, and POD-like behaviors. However, MMP9 inhibition reduced pericyte and tight junction injury and transcytosis, thereby preserving BBB function and preventing the migration of peripheral inflammation into the CNS, thus attenuating synaptic dysfunction and POD-like behavior. In addition, to further validate the above findings, we showed that melatonin exerted similar effects through inhibition of MMP9. The present study shows that after anesthesia/surgery, inflammatory cytokines upregulation is involved in regulating BBB permeability in aged mice through activation of MMP9, suggesting that MMP9 may be a potential target for the prevention of POD.

MicroRNA-195-5p Attenuates Intracerebral-Hemorrhage-Induced Brain Damage by Inhibiting MMP-9/MMP-2 Expression

Intracerebral hemorrhage (ICH) remains a devastating disease with high mortality, and there is a lack of effective strategies to improve functional outcomes. The primary injury of ICH is mechanical damage to brain tissue caused by the hematoma. Secondary injury, resulting from inflammation, red cell lysis, and thrombin production, presents a potential target for therapeutic intervention. Inflammation, crucial in secondary brain injury, involves both cellular and molecular components. MicroRNAs (miRNAs) are vital regulators of cell growth, differentiation, and apoptosis. Their deregulation may lead to diseases, and modulating miRNA expression has shown therapeutic potential, especially in cancer. Recent studies have implicated miRNAs in the pathogenesis of stroke, affecting endothelial dysfunction, neurovascular integrity, edema, apoptosis, inflammation, and extracellular matrix remodeling. Preclinical and human studies support the use of miRNA-directed gene modulation as a therapeutic strategy for ICH. Our study focused on the effects of miR-195 in ICH models. Neurological tests, including the corner turn and grip tests, indicated that miR-195 treatment led to improvements in motor function impairments caused by ICH. Furthermore, miR-195-5p significantly reduced brain edema in the ipsilateral hemisphere and restored blood-brain barrier (BBB) integrity, as shown by reduced Evans blue dye extravasation. These results suggest miR-195-5p's potential in attenuating ICH-induced apoptosis, possibly related to its influence on MMP-9 and MMP-2 expression, enzymes associated with secondary brain injury. The anti-apoptotic effects of miR-195-5p, demonstrated through TUNEL assays, further underscore its therapeutic promise in addressing the secondary brain injury and apoptosis associated with ICH. In conclusion, miR-195-5p demonstrates a significant neuroprotective effect against ICH-induced neural damage, brain edema, and BBB disruption, primarily through the downregulation of MMP-9 and MMP-2. Our findings indicate that miR-195-5p holds therapeutic potential in managing cerebral cell death following ICH.

The Roles of RhoA/ROCK/NF-κB Pathway in Microglia Polarization Following Ischemic Stroke

Ischemic stroke is the leading cause of death and disability worldwide. Nevertheless, there still lacks the effective therapies for ischemic stroke. Microglia are resident macrophages of the central nervous system (CNS) and can initiate immune responses and monitor the microenvironment. Microglia are activated and polarize into proinflammatory or anti‑inflammatory phenotype in response to various brain injuries, including ischemic stroke. Proinflammatory microglia could generate immunomodulatory mediators, containing cytokines and chemokines, these mediators are closely associated with secondary brain damage following ischemic stroke. On the contrary, anti-inflammatory microglia facilitate recovery following stroke. Regulating the activation and the function of microglia is crucial in exploring the novel treatments for ischemic stroke patients. Accumulating studies have revealed that RhoA/ROCK pathway and NF-κB are famous modulators in the process of microglia activation and polarization. Inhibiting these key modulators can promote the polarization of microglia to anti-inflammatory phenotype. In this review, we aimed to provide a comprehensive overview on the role of RhoA/ROCK pathway and NF-κB in the microglia activation and polarization, reveal the relationship between RhoA/ROCK pathway and NF-κB in the pathological process of ischemic stroke. In addition, we likewise discussed the drug modulators targeting microglia polarization.

MMP-9 upregulation may predict hemorrhagic transformation after endovascular thrombectomy

Background

Hemorrhagic transformation (HT) is a serious complication after endovascular thrombectomy (EVT) for patients with acute ischemic stroke (AIS). We analyzed the plasma levels of MMP-9 before and after EVT and assessed the temporal changes of MMP-9 that may be associated with, and therefore predict, HT after EVT.

Methods

We enrolled 30 AIS patients who received EVT, and 16 (53.3%) developed HT. The levels of MMP-9 in plasma collected from the arteries of AIS patients before and immediately after EVT were measured using ELISA. The percent change in MMP-9 after EVT (after/before) was calculated and compared between patients with and without HT.

Results

The median age of the AIS patients was 70 years, and 13 patients (43.3%) were men. The median National Institutes of Health Stroke Scale (NIHSS) scores of patients with HT were 18 on admission and 18 after EVT. The median NIHSS scores of patients without HT were 17 on admission and 11 after EVT. Patients with HT demonstrated significantly greater percentage increases in arterial MMP-9 levels after EVT.

Conclusion

Patients with AIS who developed HT had significantly increased arterial MMP-9 levels after EVT, suggesting that the upregulation of MMP-9 following EVT could serve as a predictive biomarker for HT.

ADAMTS13 deficiency exacerbates neuroinflammation by targeting matrix metalloproteinase-9 in ischemic brain injury

Our design aimed to explore the potential involvement of matrix metalloproteinase-9 (MMP-9) in the inflammatory response associated with acute ischemic stroke (AIS). We also aimed to preliminarily examine the potential impact of a disintegrin-like and metalloprotease with thrombospondin type I repeats-13 (ADAMTS13) on MMP-9 in AIS. We conducted oxygen-glucose deprivation models of microglia cells and mice models of AIS with middle cerebral artery occlusion (MCAO). We assessed the expression pattern of MMP-9 with western blotting (WB) and real-time quantitative PCR both in vivo and in vitro. MMP-9 downregulation was achieved by using ACE inhibitors such as trandolapril. For the MCAO model, we used ADAMTS13-deficient mice. We then evaluated the related neurological function scores, cerebral edema and infarct volume. The levels of inflammation-related proteins, such as COX2 and iNOS, were assessed using WB, and the expression of inflammatory cytokines was measured via enzyme-linked immuno sorbent assay in vivo. Our findings indicated that MMP-9 was up-regulated while ADAMTS13 was down-regulated in the MCAO model. Knockdown of MMP-9 reduced both inflammation and ischemic brain injury. ADAMTS13 prevented brain damage, improved neurological function and decreased the inflammation response in mice AIS models. Additionally, ADAMTS13 alleviated MMP-9-induced neuroinflammation in vivo. It showed that ADAMTS13 deficiency exacerbated ischemic brain injury through an MMP-9-dependent inflammatory mechanism. Therefore, the ADAMTS13-MMP-9 axis could have therapeutic potential for the treatment of AIS.

Integrated transcriptomic and proteomic profiling reveals the key molecular signatures of brain endothelial reperfusion injury

BACKGROUND

Reperfusion therapy after ischemic stroke often causes brain microvascular injury. However, the underlying mechanisms are unclear.

METHODS

Transcriptomic and proteomic analyses were performed on human cerebral microvascular endothelial cells following oxygen-glucose deprivation (OGD) or OGD plus recovery (OGD/R) to identify molecules and signaling pathways dysregulated by reperfusion. Major findings were further validated in a mouse model of cerebral ischemia and reperfusion.

RESULTS

Transcriptomic analysis identified 390 differentially expressed genes (DEGs) between the OGD/R and OGD group. Pathway analysis indicated that these genes were mostly associated with inflammation, including the TNF signaling pathway, TGF-β signaling pathway, cytokine-cytokine receptor interaction, NOD-like receptor signaling pathway, and NF-κB signaling pathway. Proteomic analysis identified 201 differentially expressed proteins (DEPs), which were primarily associated with extracellular matrix destruction and remodeling, impairment of endothelial transport function, and inflammatory responses. Six genes (DUSP1, JUNB, NFKBIA, NR4A1, SERPINE1, and THBS1) were upregulated by OGD/R at both the mRNA and protein levels. In mice with cerebral ischemia and reperfusion, brain TNF signaling pathway was activated by reperfusion, and inhibiting TNF-α with adalimumab significantly attenuated reperfusion-induced brain endothelial inflammation. In addition, the protein level of THBS1 was substantially upregulated upon reperfusion in brain endothelial cells and the peri-endothelial area in mice receiving cerebral ischemia.

CONCLUSION

Our study reveals the key molecular signatures of brain endothelial reperfusion injury and provides potential therapeutic targets for the treatment of brain microvascular injury after reperfusion therapy in ischemic stroke.

Trifluoperazine regulates blood-brain barrier permeability via the MLCK/p-MLC pathway to promote ischemic stroke recovery

Blood-brain barrier (BBB) disruption following ischemic stroke (IS) can induce significant aftereffects. Elevated calmodulin (CaM) expression following stroke causes calcium overload-a key contributor to BBB collapse. Trifluoperazine (TFP), a CaM inhibitor, reduces CaM overexpression following IS. However, it remains unclear whether TFP participates in BBB repair after IS. We administered TFP to mice subjected to middle cerebral artery occlusion (MCAO) and bEnd.3 cells subjected to oxygen-glucose deprivation (OGD). TFP treatment in MCAO mice reduced cerebral CaM expression and infarct size and decreased BBB permeability. OGD-treated bEnd.3 cells showed significantly increased CaM protein levels and reduced tight junction (TJ) protein levels; these changes were reversed by TFP treatment. Our results found that TFP administration in mice inhibited actin contraction following cerebral ischemia-reperfusion by suppressing the MLCK/p-MLC pathway, thereby attenuating cell retraction, improving TJ protein integrity, and reducing BBB permeability. Consequently, this treatment may promote neurological function recovery after IS.

Matrix metalloproteinases as attractive therapeutic targets for chronic pain: A narrative review

Chronic pain constitutes an abnormal pain state that detrimentally affects the quality of life, daily activities, occupational performance, and stability of mood. Despite the prevalence of chronic pain, effective drugs with potent abirritation and minimal side effects remain elusive. Substantial studies have revealed aberrant activation of the matrix metalloproteinases (MMPs) in multiple chronic pain models. Additionally, emerging evidence has demonstrated that the downregulation of MMPs can alleviate chronic pain in diverse animal models, underscoring the unique and crucial role of MMPs in different stages and types of chronic pain. This review delves into the mechanistic insights and roles of MMPs in modulating chronic pain. The aberrant activation of MMPs has been linked to neuropathic pain through mechanisms involving myelin abnormalities in peripheral nerve and spinal dorsal horn (SDH), hyperexcitability of dorsal root ganglion (DRG) neurons, activation of N-methyl-d-aspartate receptors (NMDAR) and Ca2+-dependent signals, glial cell activation, and proinflammatory cytokines release. Different MMPs also contribute significantly to inflammatory pain and cancer pain. Furthermore, we summarized the substantial therapeutic potential of MMP pharmacological inhibitors across different types of chronic pain. Overall, our findings underscore the promising therapeutic prospects of MMPs targeting for managing chronic pain.

Cerebral neurotoxicity of amino-modified polystyrene nanoplastics in mice and the protective effects of functional food Camellia pollen

Accumulating evidence suggests that nanoplastics contribute to an increased risk of brain damage, however, the precise underlying mechanisms remain unclear. Here, we subjected mice to long-term exposure to amino-modified polystyrene nanoplastics (APS-NPs). These nanoplastics were detected in the mouse brain; coupled with the observed upregulation of Alzheimer's disease-associated genes (APP and MAPT). To further explore nanoplastic damage mechanisms and the corresponding protective strategies against these mechanisms in vitro, we used hCMEC/D3 and HT22 cells. Results showed that APS-NPs disrupted tight junction proteins (Occludin and ZO-1) via TLR2/MMP9 axis, resulting in blood-brain barrier permeation; this was significantly mitigated by functional food Camellia pollen treatment. APS-NPs initiated iNOS and nNOS upregulation within neurons resulting in Sirtuin 1 deacetylase inactivation and CBP acetyltransferase stimulation, ultimately leading to Ac-Tau formation. This process was attenuated by Camellia pollen, which also ameliorated the APS-NPs-induced neuronal apoptosis mediated by the p53/Bax/Bcl-2 axis. Network pharmacology analysis of Camellia pollen offered a further theoretical understanding of its potential applications in preventing and treating nervous system disorders, such as Alzheimer's disease. This study established that Camellia pollen protects the brain against APS-NPs-mediated blood-brain barrier damage and alleviates neuronal apoptosis and Alzheimer's disease-like neurotoxicity. This study elucidates the mechanisms underlying polystyrene-induced brain damage and can be used to inform future prevention and treatment strategies.

Acteoside alleviates blood-brain barrier damage induced by ischemic stroke through inhibiting microglia HMGB1/TLR4/NLRP3 signaling

Ischemic stroke (IS) can cause severe harm, inducing oxidative stress, inflammation, and pyroptotic death. IS treatment efficacy remains limited, and microglia are important regulators of IS-related blood-brain barrier (BBB) damage. It is thus vital that new therapeutic agents capable of targeting microglia be identified to treat IS-related damage to the BBB. Acteoside (ACT), which is a compound derived from Cistanche tubulosa (Schenk) Wight., offers promising bioactivity, but its ability to protect against central nervous system injury remains to be documented. To clarify the protective benefits and mechanisms through which ACT can protect against damage to the BBB, a rat middle cerebral artery occlusion (MCAO) model system was herein employed. These in vivo analyses demonstrated that ACT was able to significantly reduce cerebral infarct size while improving their neurological scores and altering neurotrophic and inflammatory factor release. RNA sequencing and molecular docking studies highlighted the ability of ACT to exert its protective benefits via the HMGB1/TLR4/NLRP3 axis. Western immunoblotting and immunofluorescent staining for tight junction proteins additionally confirmed the ability of ACT to preserve BBB integrity. The underlying mechanisms were then explored with an oxygen-glucose deprivation (OGD) model in vitro with BV2 cells. This strategy thus confirmed that the ability of ACT to suppress microglial inflammatory and pyroptotic activity was HMGB1/TLR4/NLRP3 pathway-dependent. These data thus offer novel evidence that ACT can protect against IS-related damage to the BBB through the abrogation of inflammatory and pyroptotic activity, underscoring its promise as a novel lead compound for the therapeutic treatment of IS.

Cenicriviroc prevents dysregulation of astrocyte/endothelial cross talk induced by ischemia and HIV-1 via inhibiting the NLRP3 inflammasome and pyroptosis

Blood-brain barrier (BBB) breakdown is one of the pathophysiological characteristics of ischemic stroke, which may contribute to the progression of brain tissue damage and subsequent neurological impairment. Human immunodeficiency virus (HIV)-infected individuals are at greater risk for ischemic stroke due to diminished immune function and HIV-associated vasculopathy. Studies have shown that astrocytes are involved in maintaining BBB integrity and facilitating HIV-1 infection in the brain. The present study investigated whether targeting astrocyte-endothelial cell signaling with cenicriviroc (CVC), a dual chemokine receptor (CCR)2 and CCR5 antagonist, may protect against dysregulation of cross talk between these cells after oxygen-glucose deprivation/reoxygenation (OGD/R) combined with HIV-1 infection. Permeability assay with 10 kDa fluorescein isothiocyanate (FITC)-dextran demonstrated that CVC alleviated endothelial barrier disruption in noncontact coculture of human brain microvascular endothelial cells (HBMECs) with HIV-1-infected human astrocytes, and reversed downregulation of tight junction protein claudin-5 induced by OGD/R- and HIV-1. Moreover, CVC attenuated OGD/R- and HIV-1-triggered upregulation of the NOD-like receptor protein-3 (NLRP3) inflammasome and IL-1β secretion. Treatment with CVC also suppressed astrocyte pyroptosis by attenuating cleaved caspase-1 levels and the formation of cleaved N-terminal GSDMD (N-GSDMD). Secretome profiling revealed that CVC ameliorated secretion levels of chemokine CC chemokine ligand 17 (CCL17), adhesion molecule intercellular adhesion molecule-1 (ICAM-1), and T cell activation modulator T cell immunoglobulin and mucin domain 3 (TIM-3) by astrocytes synergistically induced by OGD/R and HIV-1. Overall, these results suggest that CVC contributes to restoring astrocyte-endothelial cross interactions in an astrocyte-dependent manner via protection against NLRP3 activation and pyroptosis.NEW & NOTEWORTHY The present study reveals the role of astrocytic NOD-like receptor protein-3 (NLRP3) inflammasome in dysfunctional astrocyte-endothelial cross interactions triggered in response to oxygen/glucose deprivation injury associated with human immunodeficiency virus type 1 (HIV-1) infection. Our results suggest that blocking NLRP3 inflammasome activation and pyroptosis-mediated inflammation with cenicriviroc (CVC) may constitute a potentially effective therapeutic strategy for blood-brain barrier (BBB) protection during HIV-1-associated ischemic stroke.

A Brain-Protective Sterol from Soft Coral Inhibits Lipopolysaccharide-Induced Matrix Metalloproteinase-9-Mediated Astrocytic Migration

Matrix metalloproteinases (MMPs), which are proteolytic enzymes, promote blood-brain barrier (BBB) disruption, leading to neuronal damage and neuroinflammation. Among them, MMP-9 upregulation serves as an inflammatory biomarker in the central nervous system (CNS). Currently, the development of marine organism-derived bioactive compounds or metabolites as anti-inflammatory drugs has received considerable attention. The 9,11-secosteroid, 3β,11-dihydroxy-9,11-secogorgost-5-en-9-one (4p3f), is a novel sterol compound extracted from the soft coral Sinularia leptoclado with potential anti-inflammatory activity. However, the effect of and potential for brain protection of 4p3f on brain astrocytes remain unclear. Herein, we used rat brain astrocytes (RBAs) to investigate the effects and signaling mechanisms of 4p3f on lipopolysaccharide (LPS)-induced MMP-9 expression via zymographic, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blot, immunofluorescence staining, promoter-reporter, and cell migration analyses. We first found that 4p3f blocked LPS-induced MMP-9 expression in RBAs. Next, we demonstrated that LPS induced MMP-9 expression via the activation of ERK1/2, p38 MAPK, and JNK1/2, which is linked to the STAT3-mediated NF-κB signaling pathway. Finally, 4p3f effectively inhibited LPS-induced upregulation of MMP-9-triggered RBA cell migration. These data suggest that a novel sterol from soft coral, 4p3f, may have anti-inflammatory and brain-protective effects by attenuating these signaling pathways of MMP-9-mediated events in brain astrocytes. Accordingly, the soft coral-derived sterol 4p3f may emerge as a potential candidate for drug development or as a natural compound with neuroprotective properties.

Biomarkers of Neurological Damage: From Acute Stage to Post-Acute Sequelae of COVID-19

Background: Neurological symptoms (NS) in COVID-19 are related to both acute stage and long-COVID. We explored levels of brain injury biomarkers (NfL and GFAP) and myeloid activation marker (sCD163) and their implications on the CNS. Materials and Methods: In hospitalized COVID-19 patients plasma samples were collected at two time points: on hospital admission (baseline) and three months after hospital discharge (Tpost). Patients were stratified according to COVID-19 severity based on acute respiratory distress syndrome (ARDS) onset (severe and non-severe groups). A further stratification according to the presence of NS (with and without groups) at baseline (requiring a puncture lumbar for diagnostic purposes) and according to NS self-referred at Tpost was performed. Finally, cerebrospinal fluid (CSF) samples were collected from patients with NS present at baseline. Results: We enrolled 144 COVID-19 patients (62 female/82 male; median age [interquartile range, IQR]): 64 [55-77]) and 53 heathy donors (HD, 30 female/23 male; median age [IQR]: 64 [59-69]). At baseline, higher plasma levels of NfL, GFAP and sCD163 in COVID-19 patients compared to HD were observed (p < 0.0001, p < 0.0001 and p < 0.0001, respectively), especially in those with severe COVID-19 (p < 0.0001, p < 0.0001 and p < 0.0001, respectively). Patients with NS showed higher plasma levels of NfL, GFAP and sCD163 compared to those without (p = 0.0023, p < 0.0001 and 0.0370, respectively). At baseline, in COVID-19 patients with NS, positive correlations between CSF levels of sCD163 and CSF levels of NfL (ρ = 0.7536, p = 0.0017) and GFAP were observed (ρ = 0.7036, p = 0.0045). At Tpost, the longitudinal evaluation performed on 77 COVID-19 patients showed a significant reduction in plasma levels of NfL, GFAP and sCD163 compared to baseline (p < 0.0001, p < 0.0001 and p = 0.0413, respectively). Finally, at Tpost, in the severe group, higher plasma levels of sCD163 in patients with NS compared to those without were reported (p < 0.0001). Conclusions: High plasma levels of NfL, GFAP and sCD163 could be due to a proinflammatory systemic and brain response involving microglial activation and subsequent CNS damage. Our data highlight the association between myeloid activation and CNS perturbations.

Astaxanthin: A Marine Drug That Ameliorates Cerebrovascular-Damage-Associated Alzheimer's Disease in a Zebrafish Model via the Inhibition of Matrix Metalloprotease-13

Alzheimer's disease (AD) is a major type of dementia disorder. Common cognitive changes occur as a result of cerebrovascular damage (CVD) via the disruption of matrix metalloproteinase-13 (MMP-13). In diabetic cases, the progress of vascular dementia is faster and the AD rate is higher. Patients with type 2 diabetes are known to have a higher risk of the factor for AD progression. Hence, this study is designed to investigate the role of astaxanthin (AST) in CVD-associated AD in zebrafish via the inhibition of MMP-13 activity. CVD was developed through the intraperitoneal and intracerebral injection of streptozotocin (STZ). The AST (10 and 20 mg/L), donepezil (1 mg/L), and MMP-13 inhibitor (i.e., CL-82198; 10 μM) were exposed for 21 consecutive days in CVD animals. The cognitive changes in zebrafish were evaluated through light and dark chamber tests, a color recognition test, and a T-maze test. The biomarkers of AD pathology were assessed via the estimation of the cerebral extravasation of Evans blue, tissue nitrite, amyloid beta-peptide aggregation, MMP-13 activity, and acetylcholinesterase activity. The results revealed that exposure to AST leads to ameliorative behavioral and biochemical changes. Hence, AST can be used for the management of AD due to its multi-targeted actions, including MMP-13 inhibition.

Bibliometric and visualization analysis of matrix metalloproteinases in ischemic stroke from 1992 to 2022

Background

Matrix metalloproteinases (MMPs) are important players in the complex pathophysiology of ischemic stroke (IS). Recent studies have shown that tremendous progress has been made in the research of MMPs in IS. However, a comprehensive bibliometric analysis is lacking in this research field. This study aimed to introduce the research status as well as hotspots and explore the field of MMPs in IS from a bibliometric perspective.

Methods

This study collected 1,441 records related to MMPs in IS from 1979 to 2022 in the web of science core collection (WoSCC) database, among them the first paper was published in 1992. CiteSpace, VOSviewer, and R package "bibliometrix" software were used to analyze the publication type, author, institution, country, keywords, and other relevant data in detail, and made descriptive statistics to provide new ideas for future clinical and scientific research.

Results

The change in the number of publications related to MMPs in IS can be divided into three stages: the first stage was from 1992 to 2012, when the number of publications increased steadily; the second stage was from 2013 to 2017, when the number of publications was relatively stable; the third stage was from 2018 to 2022, when the number of publications began to decline. The United States and China, contributing more than 64% of publications, were the main drivers for research in this field. Universities in the United States were the most active institutions and contributed the most publications. STROKE is the most popular journal in this field with the largest publications as well as the most co-cited journal. Rosenberg GA was the most prolific writer and has the most citations. "Clinical," "Medical," "Neurology," "Immunology" and "Biochemistry molecular biology" were the main research areas of MMPs in IS. "Molecular regulation," "Metalloproteinase-9 concentration," "Clinical translation" and "Cerebral ischemia-reperfusion" are the primary keywords clusters in this field.

Conclusion

This is the first bibliometric study that comprehensively mapped out the knowledge structure and development trends in the research field of MMPs in IS in recent 30 years, which will provide a reference for scholars studying this field.

Substrate derived sequences act as subsite-blocking motifs in protease inhibitory antibodies

Proteases are involved in many physiologic processes, and dysregulated proteolysis is basis of a variety of diseases. Specific inhibition of pathogenetic proteases via monoclonal antibodies therefore holds significant therapeutic promise. Inspired by the competitive mechanism utilized by many naturally occurring and man-made protease inhibitors, we hypothesized that substrate-like peptide sequences can act as protease subsite blocking motifs if they occupy only one side of the reaction center. To test this hypothesis, a degenerate codon library representing MMP-14 substrate profiles at P1-P5' positions was constructed in the context of an anti-MMP-14 Fab by replacing its inhibitory motif in CDR-H3 with MMP-14 substrate repertoires. After selection for MMP-14 active-site binders by phage panning, results indicated that diverse substrate-like sequences conferring antibodies inhibitory potencies were enriched in the isolated clones. Optimal residues at each of P1-P5' positions were then identified, and the corresponding mutation combinations showed improved characteristics as effective inhibitors of MMP-14. Insights on efficient library designs for inhibitory peptide motifs were further discussed. Overall, this study proved the concept that substrate-derived sequences were able to behave as the inhibitory motifs in protease-specific antibodies. With accumulating data available on protease substrate profiles, we expect the approach described here can be broadly applied to facilitate the generation of antibody inhibitors targeting biomedically important proteases.

Novel synergistic mechanism of 11-keto-β-boswellic acid and Z-Guggulsterone on ischemic stroke revealed by single-cell transcriptomics

Although strides have been made, the challenge of preventing and treating ischemic stroke continues to persist globally. For thousands of years, the natural substances Frankincense and Myrrh have been employed in Chinese and Indian medicine to address cerebrovascular diseases, with the key components of 11-keto-β-boswellic acid (KBA) and Z-Guggulsterone (Z-GS) being the active agents. In this study, the synergistic effect and underlying mechanism of KBA and Z-GS on ischemic stroke were examined using single-cell transcriptomics. Fourteen cell types were identified in KBA-Z-GS-treated ischemic penumbra, and microglia and astrocytes account for the largest proportion. They were further re-clustered into six and seven subtypes, respectively. GSVA analysis reflected the distinct roles of each subtype. Pseudo-time trajectory indicated that Slc1a2 and Timp1 were core fate transition genes regulated by KBA-Z-GS. In addition, KBA-Z-GS synergistically regulated inflammatory reactions in microglia and cellular metabolism and ferroptosis in astrocytes. Most notably, we established an innovative drug-gene synergistic regulation pattern, and genes regulated by KBA-Z-GS were divided into four categories based on this pattern. Finally, Spp1 was demonstrated as the hub target of KBA-Z-GS. Taken together, this study reveals the synergistic mechanism of KBA and Z-GS on cerebral ischemia, and Spp1 may be the synergistic target for that. Precise drug development targeting Spp1 may offer a potential therapeutic approach for treating ischemic stroke.

Ischemia Reperfusion Injury Induced Blood Brain Barrier Dysfunction and the Involved Molecular Mechanism

Stroke is characterized by the abrupt failure of blood flow to a specific brain region, resulting in insufficient supply of oxygen and glucose to the ischemic tissues. Timely reperfusion of blood flow can rescue dying tissue but can also lead to secondary damage to both the infarcted tissues and the blood-brain barrier, known as ischemia/reperfusion injury. Both primary and secondary damage result in biphasic opening of the blood-brain barrier, leading to blood-brain barrier dysfunction and vasogenic edema. Importantly, blood-brain barrier dysfunction, inflammation, and microglial activation are critical factors that worsen stroke outcomes. Activated microglia secrete numerous cytokines, chemokines, and inflammatory factors during neuroinflammation, contributing to the second opening of the blood-brain barrier and worsening the outcome of ischemic stroke. TNF-α, IL-1β, IL-6, and other microglia-derived molecules have been shown to be involved in the breakdown of blood-brain barrier. Additionally, other non-microglia-derived molecules such as RNA, HSPs, and transporter proteins also participate in the blood-brain barrier breakdown process after ischemic stroke, either in the primary damage stage directly influencing tight junction proteins and endothelial cells, or in the secondary damage stage participating in the following neuroinflammation. This review summarizes the cellular and molecular components of the blood-brain barrier and concludes the association of microglia-derived and non-microglia-derived molecules with blood-brain barrier dysfunction and its underlying mechanisms.