T Cell Response in Ischemic Stroke: From Mechanisms to Translational Insights

HMGB1: A New Target for Ischemic Stroke and Hemorrhagic Transformation

Stroke in China is distinguished by its high rates of morbidity, recurrence, disability, and mortality. The ultra-early administration of rtPA is essential for restoring perfusion in acute ischemic stroke, though it concurrently elevates the risk of hemorrhagic transformation. High-mobility group box 1 (HMGB1) emerges as a pivotal player in neuroinflammation after brain ischemia and ischemia-reperfusion. Released passively by necrotic cells and actively secreted, including direct secretion of HMGB1 into the extracellular space and packaging of HMGB1 into intracellular vesicles by immune cells, glial cells, platelets, and endothelial cells, HMGB1 represents a prototypical damage-associated molecular pattern (DAMP). It is intricately involved in the pathogenesis of atherosclerosis, thromboembolism, and detrimental inflammation during the early phases of ischemic stroke. Moreover, HMGB1 significantly contributes to neurovascular remodeling and functional recovery in later stages. Significantly, HMGB1 mediates hemorrhagic transformation by facilitating neuroinflammation, directly compromising the integrity of the blood-brain barrier, and enhancing MMP9 secretion through its interaction with rtPA. As a systemic inflammatory factor, HMGB1 is also implicated in post-stroke depression and an elevated risk of stroke-associated pneumonia. The role of HMGB1 extends to influencing the pathogenesis of ischemia by polarizing various subtypes of immune and glial cells. This includes mediating excitotoxicity due to excitatory amino acids, autophagy, MMP9 release, NET formation, and autocrine trophic pathways. Given its multifaceted role, HMGB1 is recognized as a crucial therapeutic target and prognostic marker for ischemic stroke and hemorrhagic transformation. In this review, we summarize the structure and redox properties, secretion and pathways, regulation of immune cell activity, the role of pathophysiological mechanisms in stroke, and hemorrhage transformation for HMGB1, which will pave the way for developing new neuroprotective drugs, reduction of post-stroke neuroinflammation, and expansion of thrombolysis time window.

T cell interactions with microglia in immune-inflammatory processes of ischemic stroke

The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke, which promotes neuronal death and inhibits nerve tissue regeneration. As the first immune cells to be activated after an ischemic stroke, microglia play an important immunomodulatory role in the progression of the condition. After an ischemic stroke, peripheral blood immune cells (mainly T cells) are recruited to the central nervous system by chemokines secreted by immune cells in the brain, where they interact with central nervous system cells (mainly microglia) to trigger a secondary neuroimmune response. This review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic stroke. We found that, during ischemic stroke, T cells and microglia demonstrate a more pronounced synergistic effect. Th1, Th17, and M1 microglia can co-secrete pro-inflammatory factors, such as interferon-γ, tumor necrosis factor-α, and interleukin-1β, to promote neuroinflammation and exacerbate brain injury. Th2, Treg, and M2 microglia jointly secrete anti-inflammatory factors, such as interleukin-4, interleukin-10, and transforming growth factor-β, to inhibit the progression of neuroinflammation, as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain injury. Immune interactions between microglia and T cells influence the direction of the subsequent neuroinflammation, which in turn determines the prognosis of ischemic stroke patients. Clinical trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic stroke. However, such studies have been relatively infrequent, and clinical experience is still insufficient. In summary, in ischemic stroke, T cell subsets and activated microglia act synergistically to regulate inflammatory progression, mainly by secreting inflammatory factors. In the future, a key research direction for ischemic stroke treatment could be rooted in the enhancement of anti-inflammatory factor secretion by promoting the generation of Th2 and Treg cells, along with the activation of M2-type microglia. These approaches may alleviate neuroinflammation and facilitate the repair of neural tissues.

Lactylation and Ischemic Stroke: Research Progress and Potential Relationship

Ischemic stroke is caused by interrupted cerebral blood flow and is a leading cause of mortality and disability worldwide. Significant advancements have been achieved in comprehending the pathophysiology of stroke and the fundamental mechanisms responsible for ischemic damage. Lactylation, as a newly discovered post-translational modification, has been reported to participate in several physiological and pathological processes. However, research on lactylation and ischemic stroke is scarce. This review summarized the current function of protein lactylation in other diseases or normal physiological processes and explored their potential link with the pathophysiological process and the reparative mechanism of ischemic stroke. We proposed that neuroinflammation, regulation of metabolism, regulation of messenger RNA translation, angiogenesis, and neurogenesis might be the bridge linking lactylation and ischemic stroke. Our study provided a novel perspective for comprehending the role of protein lactylation in the pathophysiological processes underlying ischemic stroke. Lactylation might be a promising target in drug development of ischemic stroke.

Neuroinflammation and acute ischemic stroke: impact on translational research and clinical care

Background

Stroke, encompassing both ischemic and hemorrhagic subtypes, is a leading cause of mortality and disability globally and current treatments remain limited. Neuroinflammation plays a crucial role in the pathophysiology of stroke, influencing both acute injury and long-term recovery.

Objective

This review aims to provide a comprehensive overview of neuroinflammation in stroke, detailing the mechanisms, clinical implications, and potential therapeutic strategies.

Methods

A detailed literature review was conducted, focusing on recent advancements in understanding the neuroinflammatory processes in stroke, including the roles of thromboinflammation, blood-brain barrier (BBB) disruption, and the immune response.

Results

The initial ischemic insult triggers an inflammatory cascade involving both innate and adaptive immune responses. BBB disruption allows peripheral immune cells and neurotoxic substances to infiltrate the brain, exacerbating neuronal damage and increasing the risk of infections such as pneumonia and urinary tract infections. Thromboinflammation, characterized by platelet activation and immune cell interactions, further complicates the ischemic environment. Proteomic studies have identified key biomarkers that offer insights into neuroinflammatory mechanisms and potential therapeutic targets. Advances in imaging techniques, such as PET and MRI, enable real-time monitoring of neuroinflammation, facilitating personalized treatment approaches.

Conclusion

Neuroinflammation significantly impacts stroke outcomes, presenting both challenges and opportunities for treatment. Current immunologic therapeutic strategies are limited. Future research should aim to further elucidate the complex immune interactions in stroke, refine imaging biomarkers for clinical use, and develop effective interventions to mitigate neuroinflammation.

CD4+ T cells in ischemic stroke: effects and therapeutic targets

Ischemic stroke (IS) is a significant contributor to disability and death worldwide, with limited treatments beyond early intervention. The importance of CD4+ T cells in the advancement of IS has been highlighted by recent studies, providing new insights into immunomodulatory strategies. This review describes the spatiotemporal dynamics of CD4+ T cells and their subsets at different stages of IS. The signaling pathways activated by IS regulate the distribution of CD4+ T cells and their subsets, which further influences the inflammatory response and disease progression. In the acute and subacute stages, CD4+ T cells exacerbate neuronal damage. In contrast, CD4+ T cells, which are predominantly composed of Treg cells (Tregs), promote tissue repair and neurological recovery in the chronic stage. In light of recent findings that challenge traditional views, we analyze the underlying mechanisms and potential explanations for these discrepancies. In addition, we summarize the potential of targeting CD4+ T cells as a therapeutic strategy for IS. Although no drugs specifically targeting CD4+ T cells have been developed, certain drugs that modulate CD4+ T cells show potential for IS treatment. Moreover, multitarget drugs integrated with nanomaterials are currently undergoing preclinical investigation. We further explore the challenges in the clinical translation of CD4+ T-cell-targeted therapies and discuss potential strategies to address these challenges. In conclusion, a deeper comprehension of the complex effects of CD4+ T cells and their subsets on IS will contribute to disease management and drug development, thereby improving the quality of life for IS patients.

Cross-Species Multi-Omics Analysis Reveals Myeloid-Driven Endothelial Oxidative Stress in Ischemic Stroke

BACKGROUND

Ischemic stroke is a leading cause of mortality and disability worldwide, yet the interplay between peripheral and central immune responses is still only partially understood. Emerging evidence suggests that myeloid cells, when activated in the periphery, infiltrate the ischemic brain and contribute to the disruption of the blood-brain barrier (BBB) through both inflammatory and metabolic mechanisms.

METHODS

In this study, we integrated bulk RNA-sequencing (RNA-seq), single-cell RNA-seq (scRNA-seq), spatial transcriptomics, and flow cytometry data from human and mouse models of ischemic stroke. Mouse stroke models were induced by transient middle cerebral artery occlusion (tMCAO), and brain tissues were later collected at specified time points for analysis. We examined time-dependent transcriptional changes in the peripheral blood, delineated cell-type-specific responses by single-cell profiling, and validated myeloid infiltration into the ischemic brain. We also investigated endothelial metabolic reprogramming and oxidative stress by combining scMetabolism analyses (a computational R package for inferring metabolic pathway activity at the single-cell level) with in vitro oxygen-glucose deprivation/reperfusion (OGD/R) experiments.

RESULTS

Cross-species bulk RNA-seq revealed a modest early immune shift at 3 h post-stroke, escalating significantly by 24 h, with robust myeloid-centric gene signatures conserved in humans and mice. Single-cell analyses confirmed a pronounced expansion of neutrophils, monocytes, and megakaryocytes in peripheral blood, coupled with a decrease in T and B lymphocytes. Spatial transcriptomics and flow cytometry demonstrated substantial infiltration of CD11b+ myeloid cells into the infarct core, which showed extensive interaction with endothelial cells. Endothelial scRNA-seq data showed reductions in the oxidative phosphorylation, glutathione, and nicotinate metabolic pathways, together with elevated pentose phosphate pathway activity, suggestive of oxidative stress and compromised antioxidant capacity. Functional scoring further indicated diminished endothelial inflammation/repair potential, while in vitro OGD/R experiments revealed morphological disruption, CD31 downregulation, and increased 4-hydroxynonenal (4-HNE), underscoring the importance of endothelial oxidative damage in BBB breakdown.

CONCLUSIONS

These multi-omics findings highlight the existence of a coordinated peripheral-central immune axis in ischemic stroke, wherein myeloid cell recruitment and endothelial metabolic vulnerability jointly exacerbate inflammation and oxidative stress. The targeting of endothelial oxidative injury and myeloid-endothelial crosstalk may represent a promising strategy to mitigate secondary brain injury in ischemic stroke.

Exploration of the shared gene signatures and molecular mechanisms between cardioembolic stroke and ischemic stroke

Introduction

This study aimed to investigate the shared molecular mechanisms underlying cardioembolic stroke (CS) and ischemic stroke (IS) using integrated bioinformatics analysis.

Methods

Microarray datasets for the CS (GSE58294, blood samples from CS and controls) and IS (GSE16561, blood from IS and controls; GSE22255, peripheral blood mononuclear cells from IS and matched controls) were acquired from the Gene Expression Omnibus database. Differential expression analysis and weighted gene co-expression network analysis were utilized to identify shared genes between the two diseases. Protein-protein interaction (PPI) network and topology analyses were conducted to identify the core shared genes. Three machine learning algorithms were employed to detect biomarkers from the core shared genes, and the diagnostic value of the hub genes was evaluated by establishing a predictive nomogram. Immune infiltration was evaluated using single-sample gene set enrichment analysis (ssGSEA), and pathways were analyzed with gene set enrichment analysis.

Results

There were 125 shared up-regulated genes and 2 shared down-regulated between CS and IS, which were mainly involved in immune inflammatory response-related biological functions. The Maximum Clique Centrality algorithm identified 25 core shared genes in the PPI network constructed using the shared genes. ABCA1, CLEC4E, and IRS2 were identified as biomarkers for both CS and IS and performed well in predicting the onset risk of CS and IS. All three biomarkers were highly expressed in both CS and IS compared to their corresponding controls. These biomarkers significantly correlated with neutrophil infiltration and autophagy activation in both CS and IS. Particularly, all three biomarkers were associated with the activation of neutrophil extracellular trap formation, but only in the IS.

Conclusion

ABCA1, CLEC4E, and IRS2 were identified as potential key biomarkers and therapeutic targets for CS and IS. Autophagy and neutrophil infiltration may represent the common mechanisms linking these two diseases.

Profiling X chromosome genes expression relevant to sex dimorphism in stroke: insights from transcriptomics landscape analysis

Introduction

Although age is the most important non-modifiable risk factor for cerebral stroke, it is also apparent that females commonly exhibit longer lifespan and better outcome after stroke compared to the age-matched males. A critical event after stroke is the peripheral infiltration of immune cells across damaged blood-brain barrier, which induces inflammatory and immune responses within the brain parenchyma and consequently worsen brain injury. These events are also dependent on age and display a sex different pattern. Theoretically, X chromosome-encoded differential expression genes (DEGs) may explain differences between the sexes. However, the expression and regulation of these DEGs after stroke have not been studied in detail.

Methods

We conducted three datasets of human blood cells, mice brain, mice microglia and T cells that were previously published, and analyzed the contribution of gender, age and stroke insult on the X chromosome-encoded DEGs.

Results

The main findings were (i) compared to age, the stroke/hypoxia was a more potent factor in eliciting the DEGs. Particularly, older stroke patients exhibited more changes compared to young stroke group. (ii) After a stroke, the DEGs was diversely influenced by sex, age and cell types being studied. Particularly, either aging or gender led to more striking changes in brain-infiltrating T cells than in the resident immune cells.

Discussion

These findings highlight the complex interplay between sex, age, and immune responses in mediating stroke incidence and outcome. Investigation of the identified X chromosome-encoded genes in brain-infiltrating T cells deserves high priority, as they may play more important roles in explaining gender-related differences in stroke and brain injury.

Umbilical mesenchymal stem cells mitigate T-cell compartments shift and Th17/Treg imbalance in acute ischemic stroke via mitochondrial transfer

BACKGROUND

Acute ischemic stroke (AIS) initiates secondary injuries that worsen neurological damage and hinder recovery. While peripheral immune responses play a key role in stroke outcomes, clinical results from immunotherapy have been suboptimal, with limited focus on T-cell dynamics. Umbilical mesenchymal stem cells (UMSCs) offer therapeutic potential due to their immunomodulatory properties. They can regulate immune responses and reduce neuroinflammation, potentially enhancing recovery by fostering a pro-regenerative peripheral immune environment. However, the effect of UMSCs on T-cell dynamics in AIS remains underexplored. This study investigates T-cell dynamics following AIS and examines how UMSCs may mitigate immune dysregulation to develop better treatment strategies.

METHODS

AIS patients (NIHSS scores 0-15) were recruited within 72 h of stroke onset, with peripheral blood samples collected on Day 0 (enrollment) and Day 7. T-cell compartments were identified by flow cytometry, and plasma cytokine levels were quantified using a cytometric bead array (CBA). Mitochondria in UMSCs were labeled with MitoTracker. Peripheral blood mononuclear cells from patients were isolated, treated with lipopolysaccharide (LPS), and cocultured with UMSCs in both direct contact and Transwell systems. Flow cytometry, CBA, RT-qPCR, and immunofluorescence assays were used to detect T-cell compartments, gene expression markers for helper T (Th) cell differentiation, cytokine profiles, mitochondrial transfer, reactive oxygen species (ROS) production, and mitochondrial membrane potential. Additionally, mitochondrial DNA in UMSCs was depleted. The effects of UMSCs and mitochondria-depleted UMSCs on ischemic stroke mice were compared through behavioral assessments and analysis of the peripheral immune microenvironment.

RESULTS

In AIS, T-cell compartments underwent a phenotypic shift from naïve to effector or memory states, with a specific increase in Th17 cells and a decrease in regulatory T cells, leading to alterations in T-cell-mediated immune functions. In an ex vivo co-culture system, LPS stimulation further amplified these disparities, inducing mitochondrial dysfunction and oxidative stress in T cells. Notably, UMSCs restored mitochondrial function and reversed the shift in T-cell compartments through mitochondrial transfer. Critically, UMSC treatment significantly improved both neurological deficits and peripheral immune disorders in ischemic stroke mice, whereas mitochondria-depleted UMSCs failed to produce this effect.

CONCLUSIONS

Our comprehensive insights into the key attributes of T-cell compartments in acute ischemic stroke and the immune regulatory mechanisms of UMSCs provide a crucial theoretical foundation for understanding peripheral immune disorders in ischemic stroke and the therapeutic potential of UMSC treatment.

The Aging Immune System: A Critical Attack on Ischemic Stroke

Ischemic stroke caused by cerebrovascular embolism is an age-related disease with high rates of disability and mortality. Although the mechanisms of immune and inflammatory development after stroke have been of great interest, most studies have neglected the critical and unavoidable factor of age. As the global aging trend intensifies, the number of stroke patients is constantly increasing, emphasizing the urgency of finding effective measures to address the needs of elderly stroke patients. The concept of "immunosenescence" appears to explain the worse stroke outcomes in older individuals. Immune remodeling due to aging involves dynamic changes at all levels of the immune system, and the overall consequences of central (brain-resident) and peripheral (non-brain-resident) immune cells in stroke vary according to the age of the individual. Lastly, the review outlines recent strategies aimed at immunosenescence to improve stroke prognosis.

Extracellular cold-inducible RNA-binding protein in CNS injury: molecular insights and therapeutic approaches

Central nervous system (CNS) injuries, such as ischemic stroke (IS), intracerebral hemorrhage (ICH) and traumatic brain injury (TBI), are a significant global burden. The complex pathophysiology of CNS injury is comprised of primary and secondary injury. Inflammatory secondary injury is incited by damage-associated molecular patterns (DAMPs) which signal a variety of resident CNS cells and infiltrating immune cells. Extracellular cold-inducible RNA-binding protein (eCIRP) is a DAMP which acts through multiple immune and non-immune cells to promote inflammation. Despite the well-established role of eCIRP in systemic and sterile inflammation, its role in CNS injury is less elucidated. Recent literature suggests that eCIRP is a pleiotropic inflammatory mediator in CNS injury. eCIRP is also being evaluated as a clinical biomarker to indicate prognosis in CNS injuries. This review provides a broad overview of CNS injury, with a focus on immune-mediated secondary injury and neuroinflammation. We then review what is known about eCIRP in CNS injury, and its known mechanisms in both CNS and non-CNS cells, identifying opportunities for further study. We also explore eCIRP's potential as a prognostic marker of CNS injury severity and outcome. Next, we provide an overview of eCIRP-targeting therapeutics and suggest strategies to develop these agents to ameliorate CNS injury. Finally, we emphasize exploring novel molecular mechanisms, aside from neuroinflammation, by which eCIRP acts as a critical mediator with significant potential as a therapeutic target and prognostic biomarker in CNS injury.

Effect of galangin on oxidative stress, antioxidant defenses and mitochondrial dynamics in a rat model of focal cerebral ischemia

Focal ischemia occurs when a cerebral artery becomes obstructed by an embolus or thrombus, leading to a rapid reduction in cerebral blood flow and significantly increasing the risk of mortality and disability. This condition is of particular concern in developing countries, where its prevalence is on the rise. Galangin, a flavonoid found in Alpinia officinarum, shows strong antioxidant, anti-inflammatory and anti-apoptotic properties. Its wide-ranging bioactivity in both in vitro and animal studies points to promising therapeutic applications. Given the role of oxidative stress in the pathophysiology of focal ischemia, the present study explored the effects of galangin on oxidative stress markers and antioxidant defenses in an animal model of the disease. A total of 60 healthy male Wistar rats were randomly assigned to six groups: Control, right middle cerebral artery occlusion (Rt.MCAO) + vehicle, Rt.MCAO + piracetam, and Rt.MCAO + galangin at doses of 25, 50 and 100 mg/kg body weight. The results indicated that 7 days of galangin treatment reduces infarct volume, malondialdehyde levels, and the density ratio of mitogen-activated protein kinase, while enhancing catalase, glutathione peroxidase and superoxide dismutase activities, and improving the density ratio of mitofusin 2 protein in the cortex and hippocampus. In conclusion, galangin showed significant in vivo potential in mitigating the pathological changes caused by cerebral ischemia, likely due to its antioxidant properties and modulation of mitochondrial dynamics. Additional research is now needed to explore the biochemical and neurological impacts of galangin in focal cerebral ischemia and to fully elucidate its mechanism of action.

Assessment of corticospinal tract damage and cytokines response in early and late stages of acute unilateral brainstem infarction patients

Background

Acute brainstem infarction is associated with high morbidity and mortality, the integrity of corticospinal tract (CST) detected via diffusion tensor imaging (DTI) can assist in predicting the motor recovery of the patients. In addition to the damage caused by ischemia and reperfusion, sterile inflammation also contributes to the brain injury after stroke. However, the changes in CST integrity detected by DTI in acute brainstem infarction have yet to be fully elucidated, and it is still unclear whether sterile inflammation can cause damage to the CST.

Methods

In this study, the acute brainstem infarction patients in the early (EABI patients, n = 19) and late (LABI patients, n = 21) stages and healthy controls (HCs, n = 22) are employed. The probabilistic tractography technique was used and the fractional anisotropy (FA) value was chosen to evaluated the integrity of the CST, the IL-6, IL-10, IL-17, IL-1β, and tumor necrosis factor (TNF)-α levels in the plasma are measured to evaluate the level of inflammation.

Results

Compared to the HCs (F = 13.634, p ANOVA < 0.001), the CST FA values on the infarcted side were abnormally elevated in EABI patients (p LSD = 0.003), and decreased in LABI patients (p LSD = 0.034). The levels of IL-6 (F = 12.311, p ANOVA < 0.001, EABI vs HCs: p LSD < 0.001, LABI vs HCs: p LSD < 0.001), IL-10 (F = 11.329, p ANOVA < 0.001, EABI vs HCs: p LSD < 0.001, LABI vs HCs: p LSD = 0.017) and IL-1β (F = 15.986, p ANOVA < 0.001, EABI vs HCs: p LSD < 0.001, LABI vs HCs: p LSD < 0.001) were increased in both EABI and LABI patients, while the IL-17 levels were elevated only in LABI patients (F = 4.258, p ANOVA = 0.019, LABI vs HCs: p LSD = 0.027). Among these cytokines, the increased IL-6 (r = 0.663, p = 0.002) and IL-1β (r = 0.615, p = 0.005) levels of EABI patients might be related to the elevated CST FA values, while the increased IL-17 (r = -0.599, p = 0.004) levels of LABI patients might contribute to the decrease of the CST FA values.

Conclusion

Our study reveals that the increased CST FA values in EABI patients may include signals generated by the immune cells which move along the CST. The sterile inflammation may contribute to the impairment of CST integrity in LABI patients.

Uncovering the dual roles of peripheral immune cells and their connections to brain cells in stroke and post-stroke stages through single-cell sequencing

Ischemic stroke is a cerebrovascular disease that affects the blood vessels and the blood supply to the brain, making it the second leading cause of death worldwide. Studies suggest that immune cells play a dual role during the inflammatory and recovery phases of stroke. However, in-depth investigations of specific cell subtypes and their differentiation trajectories remain to be elucidated. In this review, we highlight the application of single-cell RNA sequencing (scRNA-seq) for the unbiased identification of cell heterogeneity in brain and peripheral blood mononuclear cells (PBMCs) during and after a stroke. Our goal is to explore the phenotypic landscape of cells with different roles in this context. Specifically, we provide an overview of the roles, cell surface markers, immune cell-released cytokines, and intercellular interactions identified in major immune cells during and after stroke, as identified by different technologies. Additionally, we summarize the connection between immune cells in peripheral blood and the brain via their differentiation trajectories. By synthesizing the application of scRNA-seq in the combined analysis of PBMCs and brain tissue at higher sampling frequencies, we aim to unveil the dual role of peripheral immune cells, which could facilitate the development of new treatment strategies for ischemic stroke.

Identification of potential biomarkers and drug of ischemic stroke in patients with COVID-19 through machine learning

The relationship between COVID-19 and ischemic stroke (IS) has attracted significant attention, yet the precise mechanism at the gene level remains unclear. This study aims to reveal potential biomarkers and drugs for COVID-19-related IS through bioinformatics methods. We collected two gene expression profiling datasets, GSE16561 and GSE213313, and selected GSE179879 and GSE196822 as validation sets for analysis. Through analysis, we identified 77 differentially expressed genes (DEGs) shared between COVID-19 and IS. Further gene enrichment analysis revealed that these genes are primarily involved in immune regulation. By constructing a protein-protein interaction network, we screened out nine hub genes, including FCGR3A, KLRB1, IL2RB, CD2, IL7R, CCR7, CD3D, GZMK, and ITK. In LASSO regression analysis, we evaluated the ROC curve's area under the curve (AUC) scores of key genes to assess their diagnostic accuracy. Subsequently, we performed random forest (RF), Support Vector Machine Recursive Feature Elimination (SVM-RFE), and neural network construction on hub genes to ensure accurate diagnosis of IS. Finally, by intersecting the results of three algorithms (LASSO regression, random forest, and SVM), CD3D and ITK were identified as the ultimate key genes. Based on this, we predicted potential targeted drug Blinatumomab. These research findings provide clues for a deeper understanding of the biological mechanisms of COVID-19-related IS and offer new insights for exploring novel treatment approaches.

[Immunological foundations of neurological diseases]

BACKGROUND

Neurodegenerative diseases represent an increasing challenge in ageing societies, as only limited treatment options are currently available.

OBJECTIVE

New research methods and interdisciplinary interaction of different disciplines have changed the way neurological disorders are viewed and paved the way for the comparatively new field of neuroimmunology, which was established in the early 1980s. Starting from neurological autoimmune diseases, such as multiple sclerosis, knowledge about the involvement of immunological processes in other contexts, such as stroke or traumatic brain injury, has been significantly expanded in recent years.

MATERIAL AND METHODS

This review article provides an overview of the role of the immune system and the resulting potential for novel treatment approaches.

RESULTS

The immune system plays a central role in fighting infections but is also able to react to the body's own signals under sterile conditions and cause inflammation and subsequent adaptive immune responses through the release of immune mediators and the recruitment and differentiation of certain immune cell types. This can be beneficial in initiating healing processes; however, chronic inflammatory conditions usually have destructive consequences for the tissue and the organism and must be interrupted.

CONCLUSION

It is now known that different cells of the immune system play an important role in neurological diseases. Regulatory mechanisms, which are mediated by regulatory T cells or Th2 cells, are usually associated with a good prognosis, whereas inflammatory processes and polarization towards Th1 or Th17 have a destructive character. Novel immunomodulators, which are also increasingly being used in cancer treatment, can now be used in a tissue-specific manner and therefore offer great potential for use in neurological diseases.

Stereotactically intracerebral transplantation of neural stem cells for ischemic stroke attenuated inflammatory responses and promoted neurogenesis: an experimental study with monkeys

BACKGROUND

Ischemic stroke is a common neurovascular disorder with high morbidity and mortality. However, the underlying mechanism of stereotactically intracerebral transplantation of human neural stem cells (hNSCs) is not well elucidated.

MATERIALS AND METHODS

Four days after ischemic stroke induced by Rose Bengal photothrombosis, seven cynomolgus monkeys were transplanted with hNSCs or vehicles stereotactically and followed up for 84 days. Behavioral assessments, magnetic resonance imaging, blood tests, and pathological analysis were performed before and after treatment. The proteome profiles of the left and right precentral gyrus and hippocampus were evaluated. Extracellular vesicle micro-RNA (miRNA) from the peripheral blood was extracted and analyzed.

RESULTS

hNSC transplantation reduced the remaining infarcted lesion volume of cynomolgus monkeys with ischemic stroke without remarkable side effects. Proteomic analyses indicated that hNSC transplantation promoted GABAergic and glutamatergic neurogenesis and restored the mitochondrial electron transport chain function in the ischemic infarcted left precentral gyrus or hippocampus. Immunohistochemical staining and quantitative real-time reverse transcription PCR confirmed the promoting effects on neurogenesis and revealed that hNSCs attenuated post-infarct inflammatory responses by suppressing resident glia activation and mediating peripheral immune cell infiltration. Consistently, miRNA-sequencing revealed the miRNAs that were related to these pathways were downregulated after hNSC transplantation.

CONCLUSIONS

This study indicates that hNSCs can be effectively and safely used to treat ischemic stroke by promoting neurogenesis, regulating post-infarct inflammatory responses, and restoring mitochondrial function in both the infarct region and hippocampus.

Vascular Aging in Ischemic Stroke

Cellular senescence, a permanent halt in cell division due to stress, spurs functional and structural changes, contributing to vascular aging characterized by endothelial dysfunction and vascular remodeling. This process raises the risk of ischemic stroke (IS) in older individuals, with its mechanisms still not completely understood despite ongoing research efforts. In this review, we have analyzed the impact of vascular aging on increasing susceptibility and exacerbating the pathology of IS. We have emphasized the detrimental effects of endothelial dysfunction and vascular remodeling influenced by oxidative stress and inflammatory response on vascular aging and IS. Our goal is to aid the understanding of vascular aging and IS pathogenesis, particularly benefiting older adults with high risk of IS.

Changes in Neuroimmunological Synapses During Cerebral Ischemia

The direct interplay between the immune and nervous systems is now well established. Within the brain, these interactions take place between neurons and resident glial cells, i.e., microglia and astrocytes, or infiltrating immune cells, influenced by systemic factors. A special form of physical cell-cell interactions is the so-called "neuroimmunological (NI) synapse." There is compelling evidence that the same signaling pathways that regulate inflammatory responses to injury or ischemia also play potent roles in brain development, plasticity, and function. Proper synaptic wiring is as important during development as it is during disease states, as it is necessary for activity-dependent refinement of neuronal circuits. Since the process of forming synaptic connections in the brain is highly dynamic, with constant changes in strength and connectivity, the immune component is perfectly suited for the regulatory task as it is in constant turnover. Many cellular and molecular players in this interaction remain to be uncovered, especially in pathological states. In this review, we discuss and propose possible communication hubs between components of the adaptive and innate immune systems and the synaptic element in ischemic stroke pathology.

CCN1 Is a Therapeutic Target for Reperfused Ischemic Brain Injury

Ischemic stroke can lead to systemic inflammation, which can activate peripheral immune cells, causing neuroinflammation and brain injury. Meningeal lymphatics play a crucial role in transporting solutes and immune cells out of the brain and draining them into cervical lymph nodes (CLNs). However, the role of meningeal lymphatics in regulating systemic inflammation during the reperfusion stage after ischemia is not well understood. In this study, we demonstrated that brain infarct size, neuronal loss, and the effector function of inflammatory macrophage subsets were reduced after ischemia-reperfusion and disruption of meningeal lymphatics. Spatial memory function was improved in the late stage of ischemic stroke following meningeal lymphatic disruption. Brain-infiltrating immune cells, including neutrophils, monocytes, and T and natural killer cells, were reduced after cerebral ischemia-reperfusion and meningeal lymphatic disruption. Single-cell RNA sequencing analysis revealed that meningeal lymphatic disruption reprogrammed the transcriptome profile related to chemotaxis and leukocyte migration in CLN lymphatic endothelial cells (LECs), and it also decreased chemotactic CCN1 expression in floor LECs. Replenishment of CCN1 through intraventricular injection increased brain infarct size and neuronal loss, while restoring numbers of macrophages/microglia in the brains of meningeal lymphatic-disrupted mice after ischemic stroke. Blocking CCN1 in cerebrospinal fluid reduced brain infarcts and improves spatial memory function after ischemia-reperfusion injury. In summary, this study indicates that CCN1-mediated detrimental inflammation was alleviated after cerebral ischemia-reperfusion injury and meningeal lymphatic disruption. CCN1 represents a novel therapeutic target for inhibiting systemic inflammation in the brain-CLN axis after ischemia-reperfusion injury.

Choline consumption reduces CVD risk via body composition modification

Despite extensive research on the relationship between choline and cardiovascular disease (CVD), conflicting findings have been reported. We aim to investigate the relationship between choline and CVD. Our analysis screened a retrospective cohort study of 14,663 participants from the National Health and Nutrition Examination Survey conducted between 2013 and 2018. Propensity score matching and restricted cubic splines was used to access the association between choline intake and the risk of CVD. A two-sample Mendelian randomization (MR) analysis was conducted to examine the potential causality. Additionally, sets of single cell RNA-sequencing data were extracted and analyzed, in order to explore the role of choline metabolism pathway in the progression and severity of the CVD and the underlying potential mechanisms involved. The adjusted odds ratios and 95% confidence intervals for stroke were 0.72 (0.53-0.98; p = 0.035) for quartile 3 and 0.54 (0.39-0.75; p < 0.001) for quartile 4. A stratified analysis revealed that the relationship between choline intake and stroke varied among different body mass index and waist circumference groups. The results of MR analysis showed that choline and phosphatidylcholine had a predominantly negative causal effect on fat percentage, fat mass, and fat-free mass, while glycine had opposite effects. Results from bioinformatics analysis revealed that alterations in the choline metabolism pathway following stroke may be associated with the prognosis. Our study indicated that the consumption of an appropriate quantity of choline in the diet may help to protect against CVD and the effect may be choline-mediated, resulting in a healthier body composition. Furthermore, the regulation of the choline metabolism pathway following stroke may be a promising therapeutic target.

Research progress and challenges of stem cell therapy for ischemic stroke

Ischemic stroke is a significant global cause of death and disability. Currently, treatment options for acute ischemic stroke are limited to intravenous thrombolysis and mechanical recanalization. Therefore, novel neuroprotective strategies are imperative. Stem cell transplantation possesses the capabilities of differentiation, proliferation, neuronal replacement, nerve pathway reconstruction, secretion of nerve growth factors, and enhancement of the microenvironment; thus, it is a potential therapeutic approach for ischemic stroke. In addition, the immunomodulatory function of stem cells and the combined treatment of stem cells and exosomes exhibit a favorable protective effect on brain injury and neurological dysfunction following stroke. Meanwhile, the theory of microbiota-gut-brain axis provides us with a novel perspective for comprehending and managing neurological diseases. Lastly, stem cell transplantation has demonstrated promising outcomes not only in treating ischemic stroke but also in dealing with other neurological disorders, such as brain tumors. Furthermore, challenges related to the tissue source, delivery method, immune response, and timing of transplantation still need to be addressed to optimize the treatment.

Mechanisms of inflammation after ischemic stroke in brain-peripheral crosstalk

Stroke is a devastating disease with high morbidity, disability, and mortality, among which ischemic stroke is more common. However, there is still a lack of effective methods to improve the prognosis and reduce the incidence of its complications. At present, there is evidence that peripheral organs are involved in the inflammatory response after stroke. Moreover, the interaction between central and peripheral inflammation includes the activation of resident and peripheral immune cells, as well as the activation of inflammation-related signaling pathways, which all play an important role in the pathophysiology of stroke. In this review, we discuss the mechanisms of inflammatory response after ischemic stroke, as well as the interactions through circulatory pathways between peripheral organs (such as the gut, heart, lung and spleen) and the brain to mediate and regulate inflammation after ischemic stroke. We also propose the potential role of meningeal lymphatic vessels (MLVs)-cervical lymph nodes (CLNs) as a brain-peripheral crosstalk lymphatic pathway in ischemic stroke. In addition, we also summarize the mechanisms of anti-inflammatory drugs in the treatment of ischemic stroke.

Nanomaterial-Based Strategies for Attenuating T-Cell-Mediated Immunodepression in Stroke Patients: Advancing Research Perspectives

This review article discusses the potential of nanomaterials in targeted therapy and immunomodulation for stroke-induced immunosuppression. Although nanomaterials have been extensively studied in various biomedical applications, their specific use in studying and addressing immunosuppression after stroke remains limited. Stroke-induced neuroinflammation is characterized by T-cell-mediated immunodepression, which leads to increased morbidity and mortality. Key observations related to immunodepression after stroke, including lymphopenia, T-cell dysfunction, regulatory T-cell imbalance, and cytokine dysregulation, are discussed. Nanomaterials, such as liposomes, micelles, polymeric nanoparticles, and dendrimers, offer advantages in the precise delivery of drugs to T cells, enabling enhanced targeting and controlled release of immunomodulatory agents. These nanomaterials have the potential to modulate T-cell function, promote neuroregeneration, and restore immune responses, providing new avenues for stroke treatment. However, challenges related to biocompatibility, stability, scalability, and clinical translation need to be addressed. Future research efforts should focus on comprehensive studies to validate the efficacy and safety of nanomaterial-based interventions targeting T cells in stroke-induced immunosuppression. Collaborative interdisciplinary approaches are necessary to advance the field and translate these innovative strategies into clinical practice, ultimately improving stroke outcomes and patient care.

The Involvement of Immune Cells Between Ischemic Stroke and Gut Microbiota

Ischemic stroke, a disease with high mortality and disability rate worldwide, currently has no effective treatment. The systemic inflammation response to the ischemic stroke, followed by immunosuppression in focal neurologic deficits and other inflammatory damage, reduces the circulating immune cell counts and multiorgan infectious complications such as intestinal and gut dysfunction dysbiosis. Evidence showed that microbiota dysbiosis plays a role in neuroinflammation and peripheral immune response after stroke, changing the lymphocyte populations. Multiple immune cells, including lymphocytes, engage in complex and dynamic immune responses in all stages of stroke and may be a pivotal moderator in the bidirectional immunomodulation between ischemic stroke and gut microbiota. This review discusses the role of lymphocytes and other immune cells, the immunological processes in the bidirectional immunomodulation between gut microbiota and ischemic stroke, and its potential as a therapeutic strategy for ischemic stroke.

Impact of Immune Cells on Stroke Limited to Specific Subtypes: Evidence from Mendelian Randomization Study

INTRODUCTION

Stroke is one of the common diseases that pose a severe threat to human health, with immune cells playing a crucial role in its onset and recovery. However, the specific mechanisms and causal relationships of different immune cell groups in various clinical stroke subtypes are unclear. This study explored the causal relationship between immune cells and stroke and its subtypes using Mendelian randomization (MR) analysis.

METHODS

Data from genome-wide association studies were analyzed using inverse-variance weighted (IVW), MR-Egger, and weighted median methods for MR analysis, along with heterogeneity tests, sensitivity analysis, and pleiotropy analysis.

RESULTS

CD45RA+CD28-CD8+ T cell %T cell (OR 1.002, 95% CI 1.001-1.003; PFDR = 0.02), CD27 on CD24+CD27+ B cell (OR 1.127, 95% CI 1.061-1.198; PFDR = 0.04), CD27 on IgD-CD38dim B cell (OR 1.138, 95% CI 1.076-1.203; PFDR = 0.005), and CD27 on switched memory B cell (OR 1.144, 95% CI 1.076-1.216; PFDR = 0.01) were found to increase the risk of large artery stroke. Switched memory B cell %lymphocyte (OR 1.206, 95% CI 1.103-1.318; PFDR = 0.02) increased the risk of small vessel stroke. Reverse MR analysis did not reveal any reverse causal associations. Furthermore, by substituting the outcome data, a secondary MR analysis was conducted to validate the primary findings.

CONCLUSION

Our study reveals several causal links between immune phenotypes and stroke and its different subtypes, highlighting the complex interactions between the immune system and stroke. These findings provide new directions for further uncovering the biological basis of stroke and assist in advancing research on early interventions and treatment strategies.

Cerebroprotective Effects of the TLR4-Binding DNA Aptamer ApTOLL in a Rat Model of Ischemic Stroke and Thrombectomy Recanalization

ApTOLL, a TLR4 modulator aptamer, has demonstrated cerebroprotective effects in a permanent ischemic stroke mouse model, as well as safety and efficacy in early phase clinical trials. We carried out reverse translation research according to STAIR recommendations to further characterize the effects and mechanisms of ApTOLL after transient ischemic stroke in rats and to better inform the design of pivotal clinical trials. Adult male rats subjected to transient middle cerebral artery occlusion were treated either with ApTOLL or the vehicle intravenously at different doses and time-points. ApTOLL was compared with TAK-242 (a TLR4 inhibitor). Female rats were also studied. After neurofunctional evaluation, brains were removed for infarct/edema volume, hemorrhagic transformation, and histologic determinations. Peripheral leukocyte populations were assessed via flow cytometry. ApTOLL showed U-shaped dose-dependent cerebroprotective effects. The maximum effective dose (0.45 mg/kg) was cerebroprotective when given both before reperfusion and up to 12 h after reperfusion and reduced the hemorrhagic risk. Similar effects occurred in female rats. Both research and clinical ApTOLL batches induced slightly superior cerebroprotection when compared with TAK-242. Finally, ApTOLL modulated circulating leukocyte levels, reached the brain ischemic tissue to bind resident and infiltrated cell types, and reduced the neutrophil density. These results show the cerebroprotective effects of ApTOLL in ischemic stroke by reducing the infarct/edema volume, neurofunctional impairment, and hemorrhagic risk, as well as the peripheral and local immune response. They provide information about ApTOLL dose effects and its therapeutic time window and target population, as well as its mode of action, which should be considered in the design of pivotal clinical trials.

Evaluation of the causal effects of immune cells on ischemic stroke: a Mendelian randomization study

Background

Ischemic stroke (IS) is a cerebrovascular disease caused by various factors, and its etiology remains inadequately understood. The role of immune system dysfunction in IS has been increasingly recognized. Our objective was to evaluate whether circulating immune cells causally impact IS risk.

Methods

We conducted two-sample Mendelian randomization analyses to evaluate the causal effects of 731 immune cell traits on IS, utilizing publicly available genome-wide association studies (GWAS) summary statistics for 731 immune cell traits as exposure data, and two GWAS statistics for IS as outcome data. A set of sensitivity analyses, including Cochran's Q test, I 2 statistics, MR-Egger intercept test, MR-PRESSO global test, and leave-one-out sensitivity analyses, were performed to assess the robustness of the results. Additionally, meta-analyses were conducted to combine the results from the two different IS datasets. Finally, we extracted instrumental variables of immune cell traits with causal effects on IS in both IS datasets for SNP annotation.

Results

A total of 41 and 35 immune cell traits were identified to have significant causal effects on IS based on two different IS datasets, respectively. Among them, the immune cell trait CD62L- plasmacytoid Dendritic Cell AC and CD4+ CD8dim T cell%leukocyte respectively served as risk factor and protective element in both IS datasets. The robustness of the causal effects was confirmed through the sensitivity analyses. The results of the meta-analyses further support the causal effects of CD62L- plasmacytoid Dendritic Cell AC (pooled OR=1.030, 95%CI: 1.011-1.049, P=0.002) and CD4+ CD8dim T cell%leukocyte (pooled OR=0.959, 95%CI: 0.935-0.984, P=0.001). Based on these two immune cell traits, 33 genes that may be related to the causal effects were mapped.

Conclusions

Our study demonstrated the potential causal effects of circulating immune cells on IS, providing valuable insights for future studies aimed at preventing IS.

Long-Term Accumulation of T Cytotoxic 1, T Cytotoxic 17, and T Cytotoxic 17/1 Cells in the Brain Contributes to Microglia-Mediated Chronic Neuroinflammation After Ischemic Stroke

Post-stroke neuroinflammation affects the damage and recovery of neurological functions. T cells including CD8+ T cells were present in the ipsilateral hemisphere in the subacute and late phases of ischemic stroke. However, the potential roles of CD8+ T cell subsets in the progression of neuroinflammation have not been characterized. In the current mouse transient middle cerebral artery occlusion model, we investigated the existence of CD8+ T cell subsets in the ipsilateral hemisphere in the subacute and late phases of stroke. We found that ipsilateral CD8+ T cells were present on post-stroke day 3 and increased on post-stroke day 30. The day-3 ipsilateral CD8+ T cells predominantly produced interferon-γ (IFN-γ), while the day-30 ipsilateral CD8+ T cells co-expressed IFN-γ and interleukin-17A (IL-17A). In addition, evaluation of cytokines and transcription factors of the day-30 ipsilateral CD8+ T cells revealed the presence of T cytotoxic 1 (Tc1), T cytotoxic 17 (Tc17), and T cytotoxic 17/1 (Tc17/1) cells. Furthermore, based on the expression of a series of chemokine/cytokine receptors, viable ipsilateral Tc1, Tc17, and Tc17.1 cells were identified and enriched from the day-30 ipsilateral CD8+ T cells, respectively. Co-culture of microglia with ipsilateral Tc1, Tc17, or Tc17.1 cells indicated that the three CD8+ T cell subsets up-regulated the expression of pro-inflammatory mediators by microglia, with Tc17.1 cells being the most potent cell in doing so. Collectively, this study sheds light on the contributions of Tc1, Tc17, and Tc17.1 cells to long-term neuroinflammation after ischemic stroke.

Neuroinflammation and Epilepsy: From Pathophysiology to Therapies Based on Repurposing Drugs

Neuroinflammation and epilepsy are different pathologies, but, in some cases, they are so closely related that the activation of one of the pathologies leads to the development of the other. In this work, we discuss the three main cell types involved in neuroinflammation, namely (i) reactive astrocytes, (ii) activated microglia, and infiltration of (iii) peripheral immune cells in the central nervous system. Then, we discuss how neuroinflammation and epilepsy are interconnected and describe the use of different repurposing drugs with anti-inflammatory properties that have been shown to have a beneficial effect in different epilepsy models. This review reinforces the idea that compounds designed to alleviate seizures need to target not only the neuroinflammation caused by reactive astrocytes and microglia but also the interaction of these cells with infiltrated peripheral immune cells.

Th17 Cells and IL-17A in Ischemic Stroke

The neurological injury and repair mechanisms after ischemic stroke are complex. The inflammatory response is present throughout stroke onset and functional recovery, in which CD4 + T helper(Th) cells play a non-negligible role. Th17 cells, differentiated from CD4 + Th cells, are regulated by various extracellular signals, transcription factors, RNA, and post-translational modifications. Th17 cells specifically produce interleukin-17A(IL-17A), which has been reported to have pro-inflammatory effects in many studies. Recently, experimental researches showed that Th17 cells and IL-17A play an important role in promoting stroke pathogenesis (atherosclerosis), inducing secondary damage after stroke, and regulating post-stroke repair. This makes Th17 and IL-17A a possible target for the treatment of stroke. In this paper, we review the mechanism of action of Th17 cells and IL-17A in ischemic stroke and the progress of research on targeted therapy.

Causal effects of immune cell surface antigens and functional outcome after ischemic stroke: a Mendelian randomization study

Objective

While observational studies link immune cells with post-stroke functional outcome, the underlying immune mechanisms are not well understood. Immune cell surface antigens are actively involved in the biological behavior of immune cells, investigating immune cell surface antigens could deepen our comprehension of their role and biological processes in stroke recovery. Therefore, we aimed to investigate the immunological basis of stroke outcome by exploring the causal relationship between immune cell surface antigens and functional outcome after ischemic stroke in a Mendelian randomization study.

Methods

Genetic variants related to immune cell surface antigens and post-stroke functional outcome were selected for two-sample Mendelian randomization (MR) analysis. 389 fluorescence intensities (MFIs) with surface antigens were included. Inverse variance weighted (IVW) modeling was used as the primary MR method to estimate the causal effect of exposure on the outcome, followed by several alternative methods and sensitivity analyses. Additional analysis of the association between immune cell surface antigens and risk of ischemic stroke for assessment of collider bias.

Results

We found that suggestive associations between CD20 on switched memory B cell (OR = 1.16, 95% CI: 1.01-1.34, p = 0.036) and PDL-1 on monocyte (OR = 1.32, 95% CI: 1.04-1.66, p = 0.022) and poor post-stroke functional outcome, whereas CD25 on CD39+ resting Treg (OR = 0.77, 95% CI: 0.62-0.96, p = 0.017) was suggestively associated with good post-stroke functional outcome.

Conclusion

The elevated CD20 on switched memory B cell, PDL-1 on monocyte, and CD25 on CD39+ resting Treg may be novel biomarkers and potential causal factors influencing post-stroke functional outcome.

Updates of the role of B-cells in ischemic stroke

Ischemic stroke is a major disease causing death and disability in the elderly and is one of the major diseases that seriously threaten human health and cause a great economic burden. In the early stage of ischemic stroke, neuronal structure is destroyed, resulting in death or damage, and the release of a variety of damage-associated pattern molecules induces an increase in neuroglial activation, peripheral immune response, and secretion of inflammatory mediators, which further exacerbates the damage to the blood-brain barrier, exacerbates cerebral edema, and microcirculatory impairment, triggering secondary brain injuries. After the acute phase of stroke, various immune cells initiate a protective effect, which is released step by step and contributes to the repair of neuronal cells through phenotypic changes. In addition, ischemic stroke induces Central Nervous System (CNS) immunosuppression, and the interaction between the two influences the outcome of stroke. Therefore, modulating the immune response of the CNS to reduce the inflammatory response and immune damage during stroke is important for the protection of brain function and long-term recovery after stroke, and modulating the immune function of the CNS is expected to be a novel therapeutic strategy. However, there are fewer studies on B-cells in brain function protection, which may play a dual role in the stroke process, and the understanding of this cell is still incomplete. We review the existing studies on the mechanisms of the role of B-cells, inflammatory response, and immune response in the development of ischemic stroke and provide a reference for the development of adjuvant therapeutic drugs for ischemic stroke targeting inflammatory injury.

miR-142-3p/5p role in cancer: From epigenetic regulation to immunomodulation

MicroRNAs (miRNAs) play critical roles in cancer pathobiology, acting as regulators of gene expression and pivotal drivers of tumorigenesis. It is believed that miRNAs act through canonical mechanisms, involving the binding of mature miRNAs to target messenger RNAs (mRNAs) and subsequent repression of protein translation or degradation of target mRNAs. miR-142-3p/5p has been extensively studied and established as a key regulator in various malignancies. Recent discoveries have revealed miR-142-3p/5p serve as either oncogene or tumor suppressor in cancer. By targeting epigenetic factor and cancer-related signaling pathway, miR-142-3p/5p can regulate wide range of downstream genes. The immune modulatory role of miR-142-3p/5p has been shown in various cancers, which provides significant insight into immunosuppression and tumor escape from the immune response. Exosomes with miR-142-3p/5p facilitate cell communication and can affect cancer cell behavior, offering potential therapeutic, and diagnosis applications in cancer therapy. In this review, for the first time, we comprehensively summarize the current knowledge regarding mentioned functions of miR-142-3p/5p in cancer pathobiology.

Predictors for unfavorable prognosis after stroke with perforator artery disease

Background and purpose

Perforator artery disease (PAD) is an important subtype of ischemic stroke. The risk factors affecting the prognosis of patients with PAD are unclear. This study aimed to investigate the risk factors affecting the unfavorable prognosis of PAD.

Methods

Patients with PAD were enrolled from Dushu Lake Hospital Affiliated to Soochow University and diagnosed as stroke with PAD during the period from September 2021 to July 2023 and followed up with a modified Rankin Scale (mRS) after 90 days, defining the mRS of 0-2 as a group with favorable prognosis, and 3-6 as a group with unfavorable functional outcome. Logistic regression was used to identify predictors for PAD. Multiple logistic regression analysis and receiver operating characteristics (ROC) were used to identify predictors of unfavorable prognosis.

Results

Of the 181 enrolled patients, 48 (26.5%) were identified with unfavorable prognosis. On multivariate analysis, increased age (OR = 1.076, 95% CI: 1.012 ~ 1.144, p = 0.019), higher National Institutes of Health Stroke Scale (NIHSS) score at admission (OR = 2.930, 95% CI: 1. 905 ~ 4.508, p < 0.001), and increased neutrophil-to-lymphocyte ratio (NLR) (OR = 3.028, 95% CI: 1.615 ~ 5.675, p = 0.001) were independent risk factors for unfavorable prognosis in patients with PAD, and the area under the receiver operating characteristic curve was 0.590, 0.905, and 0.798, and the multi-factor diagnostic model (Model 2) showed reliable diagnostic specificity and sensitivity (area under the curve = 0.956, p < 0.001, specificity 0.805, sensitivity 0.958, accuracy 0.845).

Conclusion

Increased baseline NLR and NIHSS score and aging may be independent risk factors for unfavorable prognosis of patients with PAD. NLR can be used as a potential biological indicator to predict the prognosis of stroke with PAD.

Mechanisms of immune response and cell death in ischemic stroke and their regulation by natural compounds

Ischemic stroke (IS), which is the third foremost cause of disability and death worldwide, has inflammation and cell death as its main pathological features. IS can lead to neuronal cell death and release factors such as damage-related molecular patterns, stimulating the immune system to release inflammatory mediators, thereby resulting in inflammation and exacerbating brain damage. Currently, there are a limited number of treatment methods for IS, which is a fact necessitating the discovery of new treatment targets. For this review, current research on inflammation and cell death in ischemic stroke was summarized. The complex roles and pathways of the principal immune cells (microglia, astrocyte, neutrophils, T lymphocytes, and monocytes/macrophage) in the immune system after IS in inflammation are discussed. The mechanisms of immune cell interactions and the cytokines involved in these interactions are summarized. Moreover, the cell death mechanisms (pyroptosis, apoptosis, necroptosis, PANoptosis, and ferroptosis) and pathways after IS are explored. Finally, a summary is provided of the mechanism of action of natural pharmacological active ingredients in the treatment of IS. Despite significant recent progress in research on IS, there remain many challenges that need to be overcome.

Perspective from single-cell sequencing: Is inflammation in acute ischemic stroke beneficial or detrimental?

BACKGROUND

Acute ischemic stroke (AIS) is a common cerebrovascular event associated with high incidence, disability, and poor prognosis. Studies have shown that various cell types, including microglia, astrocytes, oligodendrocytes, neurons, and neutrophils, play complex roles in the early stages of AIS and significantly affect its prognosis. Thus, a comprehensive understanding of the mechanisms of action of these cells will be beneficial for improving stroke prognosis. With the rapid development of single-cell sequencing technology, researchers have explored the pathophysiological mechanisms underlying AIS at the single-cell level.

METHOD

We systematically summarize the latest research on single-cell sequencing in AIS.

RESULT

In this review, we summarize the phenotypes and functions of microglia, astrocytes, oligodendrocytes, neurons, neutrophils, monocytes, and lymphocytes, as well as their respective subtypes, at different time points following AIS. In particular, we focused on the crosstalk between microglia and astrocytes, oligodendrocytes, and neurons. Our findings reveal diverse and sometimes opposing roles within the same cell type, with the possibility of interconversion between different subclusters.

CONCLUSION

This review offers a pioneering exploration of the functions of various glial cells and cell subclusters after AIS, shedding light on their regulatory mechanisms that facilitate the transformation of detrimental cell subclusters towards those that are beneficial for improving the prognosis of AIS. This approach has the potential to advance the discovery of new specific targets and the development of drugs, thus representing a significant breakthrough in addressing the challenges in AIS treatment.

Signaling pathways in brain ischemia: Mechanisms and therapeutic implications

Ischemic stroke occurs when the arteries supplying blood to the brain are narrowed or blocked, inducing damage to brain tissue due to a lack of blood supply. One effective way to reduce brain damage and alleviate symptoms is to reopen blocked blood vessels in a timely manner and reduce neuronal damage. To achieve this, researchers have focused on identifying key cellular signaling pathways that can be targeted with drugs. These pathways include oxidative/nitrosative stress, excitatory amino acids and their receptors, inflammatory signaling molecules, metabolic pathways, ion channels, and other molecular events involved in stroke pathology. However, evidence suggests that solely focusing on protecting neurons may not yield satisfactory clinical results. Instead, researchers should consider the multifactorial and complex mechanisms underlying stroke pathology, including the interactions between different components of the neurovascular unit. Such an approach is more representative of the actual pathological process observed in clinical settings. This review summarizes recent research on the multiple molecular mechanisms and drug targets in ischemic stroke, as well as recent advances in novel therapeutic strategies. Finally, we discuss the challenges and future prospects of new strategies based on the biological characteristics of stroke.

Treg Cells in Ischemic Stroke: A Small Key to a Great Orchestrion

Ischemic stroke is a global medical problem and one of the leading causes of death or disability worldwide. The main approach of ischemic stroke therapy in the most acute period, which can prevent or minimize the development of a neurological deficit, is the restoration of the blood flow in the ischemic brain tissue using enzymatic thrombolysis or endovascular thromboextraction. When the therapeutic window is missed, the modulation of the acute inflammatory response may play an important role in determining the fate of neurons in the penumbra. The key players in this process are T-regulatory cells (Tregs) an immunosuppressive population of CD4+ T-cells with the CD4+, CD25+ CD127low, FoxP3+ phenotype. Despite the existing reports that Tregs (or certain Treg subpopulations) can exacerbate microcirculatory disorders in the ischemic tissue, many stadies convincingly suggest the positive role of Tregs in ischemic stroke. Resident CD69+ Tregs found in the normal mammalian brain have neuroprotective activity, produce IL-10 and other anti-inflammatory cytokines, control astrogliosis, and downregulate cytotoxic subpopulations of T cells and microglia. Systemic administration of Treg in stroke is accompained by a decrease in the volume of cerebral infarction and decreased levels of secondary neuronal death. Thus, the methods allowing Treg activation and expansion ex vivo open up several new avenues for the immunocorrection not only in systemic and autoimmune diseases, but, potentially, in the neuroprotective therapy for ischemic stroke. The relationship between Treg, inflammation, and cerebrovascular pathology is of particular interest in the case of ischemic stroke and COVID-19 as a comorbidity. It has been demonstrated that systemic inflammation caused by SARS-CoV-2 infection leads to a significant suppression of Treg, which is accompanied by an increased risk for the development of ischemic stroke and other neurological complications. Overall, the information summarized herein about the possible therapeutic potential of Treg in cerebrovascular pathology may be of practical interest not only for researchers, but also for clinicians.

Gene expression profiles of ischemic stroke clots retrieved by mechanical thrombectomy are associated with disease etiology

BACKGROUND

Determining stroke etiology is crucial for secondary prevention, but intensive workups fail to classify ~30% of strokes that are cryptogenic.

OBJECTIVE

To examine the hypothesis that the transcriptomic profiles of clots retrieved during mechanical thrombectomy are unique to strokes of different subtypes.

METHODS

We isolated RNA from the clots of 73 patients undergoing mechanical thrombectomy. Samples of sufficient quality were subjected to 100-cycle, paired-end RNAseq, and transcriptomes with less than 10 million unique reads were excluded from analysis. Significant differentially expressed genes (DEGs) between subtypes (defined by the Trial of Org 10 172 in Acute Stroke Treatment) were identified by expression analysis in edgeR. Gene ontology enrichment analysis was used to study the biologic differences between stroke etiologies.

RESULTS

In all, 38 clot transcriptomes were analyzed; 6 from large artery atherosclerosis (LAA), 21 from cardioembolism (CE), 5 from strokes of other determined origin, and 6 from cryptogenic strokes. Among all comparisons, there were 816 unique DEGs, 174 of which were shared by at least two comparisons, and 20 of which were shared by all three. Gene ontology analysis showed that CE clots reflected high levels of inflammation, LAA clots had greater oxidoreduction and T-cell processes, and clots of other determined origin were enriched for aberrant platelet and hemoglobin-related processes. Principal component analysis indicated separation between these subtypes and showed cryptogenic samples clustered among several different groups.

CONCLUSIONS

Expression profiles of stroke clots were identified between stroke etiologies and reflected different biologic responses. Cryptogenic thrombi may be related to multiple etiologies.

Effects of a Small-Molecule Perforin Inhibitor in a Mouse Model of CD8 T Cell-Mediated Neuroinflammation

BACKGROUND AND OBJECTIVES

Alteration of the blood-brain barrier (BBB) at the interface between blood and CNS parenchyma is prominent in most neuroinflammatory diseases. In several neurologic diseases, including cerebral malaria and Susac syndrome, a CD8 T cell-mediated targeting of endothelial cells of the BBB (BBB-ECs) has been implicated in pathogenesis.

METHODS

In this study, we used an experimental mouse model to evaluate the ability of a small-molecule perforin inhibitor to prevent neuroinflammation resulting from cytotoxic CD8 T cell-mediated damage of BBB-ECs.

RESULTS

Using an in vitro coculture system, we first identified perforin as an essential molecule for killing of BBB-ECs by CD8 T cells. We then found that short-term pharmacologic inhibition of perforin commencing after disease onset restored motor function and inhibited the neuropathology. Perforin inhibition resulted in preserved BBB-EC viability, maintenance of the BBB, and reduced CD8 T-cell accumulation in the brain and retina.

DISCUSSION

Therefore, perforin-dependent cytotoxicity plays a key role in the death of BBB-ECs inflicted by autoreactive CD8 T cells in a preclinical model and potentially represents a therapeutic target for CD8 T cell-mediated neuroinflammatory diseases, such as cerebral malaria and Susac syndrome.

Neuroinflammation and anti-inflammatory therapy for ischemic stroke

Stroke remains one of the most devastating and challenging neurological diseases worldwide. Inflammation, as well as oxidative stress is one of the main contributors to post-stroke injuries, and oxidative stress can further induce inflammation. Moreover, the inflammatory response is closely related to immune modulation in ischemic stroke progression. Hence, major ischemic stroke treatment strategies include targeting inflammatory responses, immune modulation (especially immune cells), and inflammatory response to suppress stroke progression. To date, several drugs have demonstrated clinical efficacy, such as Etanercept and Fingolimod. However, only edaravone dexborneol has successfully passed the phase III clinical trial and been approved by the National Medical Products Administration (NMPA) to treat ischemic stroke in China, which can restore redox balance and regulate inflammatory immune responses, thus providing neuroprotection in ischemic stroke. In this review, we will comprehensively summarize the current advances in the application of inflammatory biomarkers, neuroinflammation and neuro-immunotherapeutic scenarios for ischemic stroke, thus aiming to provide a theoretical basis and new prospects and frontiers for clinical applications.

Promoted Generation of T Helper 1-Like Regulatory T Cells After Transient Middle Cerebral Artery Occlusion in Type-2 Diabetic Mice

BACKGROUND

Regulatory T cells (Tregs) play a remarkable role in modulating post-ischemic neuroinflammation. However, the characteristics of Tregs in diabetic ischemic stroke remain unknown.

METHODS

Transient middle cerebral artery occlusion (MCAO) was conducted on leptin receptor-mutated db/db mice and db/+ mice. The number, cytokine production, and signaling features of Tregs in peripheral blood and ipsilateral hemispheres were evaluated by flow cytometry. Treg plasticity was assessed by the adoptive transfer of splenic Tregs into mice. The effect of ipsilateral macrophages/microglia on Treg plasticity was determined by in vitro co-culture analysis.

RESULTS

db/db mice had more infiltrating Tregs in their ipsilateral hemispheres than db/+ mice. Infiltrating Tregs in db/db mice expressed higher transforming growth factor-β (TGF-β), interleukin-10 (IL-10), forkhead box P3 (Foxp3), interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and T-box expressed in T cells (T-bet) in comparison to infiltrating Tregs in db/+ mice, suggesting promoted generation of T helper 1 (Th1)-like Tregs in the brains of db/db mice after stroke. The post-ischemic brain microenvironment of db/db mice significantly up-regulated IFN-γ, TNF-α, T-bet, IL-10, and TGF-β in infiltrating Tregs. Moreover, ipsilateral macrophages/microglia remarkably enhanced the expression of IFN-γ, TNF-α, and T-bet but not IL-10 and TGF-β in Tregs. db/db macrophages/microglia were more potent in up-regulating IFN-γ, TNF-α, and T-bet than db/+ macrophages/microglia. Interleukin-12 (IL-12) blockage partially abolished the modulatory effect of macrophages/microglia on Tregs.

CONCLUSION

The generation of Th1-like Tregs was promoted in the brains of type 2 diabetic mice after stroke. Our study reveals significant Treg plasticity in diabetic stroke.Abbreviations: Foxp3: forkhead box P3; IFN-γ: interferon-γ; IL-10: interleukin-10; IL-12: interleukin-12; MCAO: middle cerebral artery occlusion; PBS: phosphate-buffered saline; STAT1: Signal transducer and activator of transcription 1; STAT5: Signal transducer and activator of transcription 1; T-bet: T-box expressed in T cells; TGF-β: transforming growth factor-β; Th1: T helper 1; TNF-α: tumor necrosis factor-α; Tregs: regulatory T cells. Foxp3: forkhead box P3; IFN-γ: interferon-γ; IL-10: interleukin-10; IL-12: interleukin-12; MCAO: middle cerebral artery occlusion; PBS: phosphate-buffered saline; STAT1: Signal transducer and activator of transcription 1; STAT5: Signal transducer and activator of transcription 1; T-bet: T-box expressed in T cells; TGF-β: transforming growth factor-β; Th1: T helper 1; TNF-α: tumor necrosis factor-α; Tregs: regulatory T cells.

γδ T cells recruitment and local proliferation in brain parenchyma benefit anti-neuroinflammation after cerebral microbleeds

Background

Cerebral microbleeds (CMBs) are an early sign of many neurological disorders and accompanied by local neuroinflammation and brain damage. As important regulators of immune response and neuroinflammation, the biological behavior and role of γδ T cells after CMBs remain largely unknown.

Methods

We made a spot injury of microvessel in the somatosensory cortex to mimic the model of CMBs by two-photon laser and in vivo tracked dynamical behaviors of γδ T cells induced by CMBs using TCR-δGFP transgenic mice. Biological features of γδ T cells in the peri-CMBs parenchyma were decoded by flow cytometry and Raman spectra. In wildtype and γδ T cell-deficient mice, neuroinflammation and neurite degeneration in the peri-CMBs cortex were studied by RNAseq, immunostaining and in vivo imaging respectively.

Results

After CMBs, γδ T cells in the dural vessels were tracked to cross the meningeal structure and invade the brain parenchyma in a few days, where the division process of γδ T cells were captured. Parenchymal γδ T cells were highly expressed by CXCR6 and CCR6, similar to meningeal γδ T cells, positive for IL-17A and Ki67 (more than 98%), and they contained abundant substances for energy metabolism and nucleic acid synthesis. In γδ T cell-deficient mice, cortical samples showed the upregulation of neuroinflammatory signaling pathways, enhanced glial response and M1 microglial polarization, and earlier neuronal degeneration in the peri-CMBs brain parenchyma compared with wildtype mice.

Conclusion

CMBs induce the accumulation and local proliferation of γδ T cells in the brain parenchyma, and γδ T cells exert anti-neuroinflammatory and neuroprotective effects at the early stage of CMBs.

Neuroimmune mechanisms and therapies mediating post-ischaemic brain injury and repair

The nervous and immune systems control whole-body homeostasis and respond to various types of tissue injury, including stroke, in a coordinated manner. Cerebral ischaemia and subsequent neuronal cell death activate resident or infiltrating immune cells, which trigger neuroinflammation that affects functional prognosis after stroke. Inflammatory immune cells exacerbate ischaemic neuronal injury after the onset of brain ischaemia; however, some of the immune cells thereafter change their function to neural repair. The recovery processes after ischaemic brain injury require additional and close interactions between the nervous and immune systems through various mechanisms. Thus, the brain controls its own inflammation and repair processes after injury via the immune system, which provides a promising therapeutic opportunity for stroke recovery.

Transplanted human iPSC-derived vascular endothelial cells promote functional recovery by recruitment of regulatory T cells to ischemic white matter in the brain

BACKGROUND

Ischemic stroke in white matter of the brain induces not only demyelination, but also neuroinflammation. Peripheral T lymphocytes, especially regulatory T cells (Tregs), are known to infiltrate into ischemic brain and play a crucial role in modulation of inflammatory response there. We previously reported that transplantation of vascular endothelial cells generated from human induced pluripotent stem cells (iVECs) ameliorated white matter infarct. The aim of this study is to investigate contribution of the immune system, especially Tregs, to the mechanism whereby iVEC transplantation ameliorates white matter infarct.

METHODS

iVECs and human Tregs were transplanted into the site of white matter lesion seven days after induction of ischemia. The egress of T lymphocytes from lymph nodes was sequestered by treating the animals with fingolimod (FTY720). The infarct size was evaluated by magnetic resonance imaging. Immunohistochemistry was performed to detect the activated microglia and macrophages, T cells, Tregs, and oligodendrocyte lineage cells. Remyelination was examined by Luxol fast blue staining.

RESULTS

iVEC transplantation reduced ED-1⁺ inflammatory cells and CD4⁺ T cells, while increased Tregs in the white matter infarct. Treatment of the animals with FTY720 suppressed neuroinflammation and reduced the number of both CD4⁺ T cells and Tregs in the lesion, suggesting the importance of infiltration of these peripheral immune cells into the lesion in aggravation of neuroinflammation. Suppression of neuroinflammation by FTY720 per se, however, did not promote remyelination in the infarct. FTY720 treatment negated the increase in the number of Tregs by iVEC transplantation in the infarct, and attenuated remyelination promoted by transplanted iVECs, while it did not affect the number of oligodendrocyte lineage cells increased by iVEC transplantation. Transplantation of Tregs together with iVECs into FTY720-treated ischemic white matter did not affect the number of oligodendrocyte lineage cells, while it remarkably promoted myelin regeneration.

CONCLUSIONS

iVEC transplantation suppresses neuroinflammation, but suppression of neuroinflammation per se does not promote remyelination. Recruitment of Tregs by transplanted iVECs contributes significantly to promotion of remyelination in the injured white matter.

TCRαβ+NK1.1-CD4-CD8- double-negative T cells inhibit central and peripheral inflammation and ameliorate ischemic stroke in mice

Background: Excessive immune activation leads to secondary injury and impedes injured brain recovery after ischemic stroke. However, few effective methods are currently used for equilibrating immune balance. CD3⁺NK1.1^-TCRβ⁺CD4^-CD8^- double-negative T (DNT) cells which do not express NK cell surface markers are unique regulatory cells that maintain homeostasis in several immune-related diseases. However, the therapeutic potential and regulatory mechanism of DNT cells in ischemic stroke are still unknown. Methods: Mouse ischemic stroke is induced by occlusion of the distal branches of the middle cerebral artery (dMCAO). DNT cells were adoptively transferred intravenously into ischemic stroke mice. Neural recovery was evaluated by TTC staining and behavioral analysis. Using immunofluorescence, flow cytometry, and RNA sequencing, the immune regulatory function of DNT cells was investigated at different time points post ischemic stroke. Results: Adoptive transfer of DNT cells significantly reduces infarct volume and improves sensorimotor function after ischemic stroke. DNT cells suppress peripheral Trem1⁺ myeloid cell differentiation during the acute phase. Furthermore, they infiltrate the ischemic tissue via CCR5 and equilibrate the local immune balance during the subacute phase. During the chronic phase, DNT cells enhance Treg cell recruitment through CCL5, eventually developing an immune homeostatic milieu for neuronal recovery. Conclusions: DNT cell treatment renders the comprehensive anti-inflammatory roles in specific phases of ischemic stroke. Our study suggests that the adoptive transfer of regulatory DNT cells may be a potential cell-based therapy for ischemic stroke.

Low Lymphocyte-to-Monocyte Ratio as a Possible Predictor of an Unfavourable Clinical Outcome in Patients with Acute Ischemic Stroke after Mechanical Thrombectomy

Background

Although considerable progress has been made in the treatment of acute ischemic stroke (AIS), the clinical outcome of patients is still significantly influenced by the inflammatory response that follows stroke-induced brain injury. The aim of this study was to evaluate the potential use of complete blood count parameters, including indices and ratios, for predicting the clinical outcome in AIS patients undergoing mechanical thrombectomy (MT).

Methods

This single-centre retrospective study is consisted of 179 patients. Patient data including demographic characteristics, risk factors, clinical data, laboratory parameters on admission, and clinical outcome were collected. Based on the clinical outcome assessed at 3 months after MT by the modified Rankin Scale (mRS), patients were divided into two groups: the favourable group (mRS 0-2) and unfavourable group (mRS 3-6). Stepwise multivariate logistic regression analysis was used to detect an independent predictor of the unfavourable clinical outcome.

Results

An unfavourable clinical outcome was detected after 3 months in 101 patients (54.4%). Multivariate logistic regression analysis confirmed that the lymphocyte-to-monocyte ratio (LMR) was an independent predictor of unfavourable clinical outcome at 3 months (odds ratio = 0.761, 95% confidence interval 0.625-0.928, and P = 0.007). The value of 3.27 was chosen to be the optimal cut-off value of LMR. This value could predict the unfavourable clinical outcome with a 74.0% sensitivity and a 54.4% specificity.

Conclusion

The LMR at the time of hospital admission is a predictor of an unfavourable clinical outcome at 3 months in AIS patients after MT.

The immunopathology of B lymphocytes during stroke-induced injury and repair

B cells, also known as B lymphocytes or lymphoid lineage cells, are a historically understudied cell population with regard to brain-related injuries and diseases. However, an increasing number of publications have begun to elucidate the different phenotypes and roles B cells can undertake during central nervous system (CNS) pathology, including following ischemic and hemorrhagic stroke. B cell phenotype is intrinsically linked to function following stroke, as they may be beneficial or detrimental depending on the subset, timing, and microenvironment. Factors such as age, sex, and presence of co-morbidity also influence the behavior of post-stroke B cells. The following review will briefly describe B cells from origination to senescence, explore B cell function by integrating decades of stroke research, differentiate between the known B cell subtypes and their respective activity, discuss some of the physiological influences on B cells as well as the influence of B cells on certain physiological functions, and highlight the differences between B cells in healthy and disease states with particular emphasis in the context of ischemic stroke.