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.

Flow cytometry-based peripheral blood analysis as an easily friendly tool for prognostic monitoring of acute ischemic stroke: a multicenter study.

Background and objective: Acute ischemic stroke (AIS) is a leading cause of mortality, severe neurological and long-term disability world-wide. Blood-based indicators may provide valuable information on identified prognostic factors. However, currently, there is still a lack of peripheral blood indicators for the prognosis of AIS. We aimed to identify the most promising prognostic indicators and establish prognostic models for AIS. Methods: 484 subjects enrolled from four centers were analyzed immunophenotypic indicators of peripheral blood by flow cytometry. Least absolute shrinkage and selection operator (LASSO) regression was applied to minimize the potential collinearity and over-fitting of variables measured from the same subject and over-fitting of variables. Univariate and multivariable Cox survival analysis of differences between and within cohorts was performed by log-rank test. The areas under the receiving operating characteristic (ROC) curves were used to evaluate the selection accuracy of immunophenotypic indicators in identifying AIS subjects with survival risk. The prognostic model was constructed using a multivariate Cox model, consisting of 402 subjects as a training cohort and 82 subjects as a testing cohort. Results: In the prospective study, 7 immunophenotypic indicators of distinct significance were screened out of 72 peripheral blood immunophenotypic indicators by LASSO. In multivariate cox regression, CTL (%) [HR: 1.18, 95% CI: 1.03-1.33], monocytes/µl [HR: 1.13, 95% CI: 1.05-1.21], non-classical monocytes/µl [HR: 1.09, 95% CI: 1.02-1.16] and CD56high NK cells/µl [HR: 1.13, 95% CI: 1.05-1.21] were detected to decrease the survival probability of AIS, while Tregs/µl [HR:0.97, 95% CI: 0.95-0.99, p=0.004], BM/µl [HR:0.90, 95% CI: 0.85-0.95, p=0.023] and CD16+NK cells/µl [HR:0.93, 95% CI: 0.88-0.98, p=0.034] may have the protective effect. As for indicators' discriminative ability, the AUC for CD56highNK cells/µl attained the highest of 0.912. In stratification analysis, the survival probability for AIS subjects with a higher level of Tregs/µl, BM/µl, CD16+NK cells/µl, or lower levels of CD56highNK cells/µl, CTL (%), non-classical monocytes/µl, Monocytes/µl were more likely to survive after AIS. The multivariate Cox model showed an area under the curve (AUC) of 0.805, 0.781 and 0.819 and 0.961, 0.924 and 0.982 in the training and testing cohort, respectively. Conclusion: Our study identified 7 immunophenotypic indicators in peripheral blood may have great clinical significance in monitoring the prognosis of AIS and provide a convenient and valuable predictive model for AIS.

Elevated serum levels of anti-collagen type I antibodies in patients with spontaneous cervical artery dissection and ischemic stroke: a prospective multicenter study.

Introduction: Spontaneous cervical artery dissection (sCAD) is a rare vasculopathy whose trigger is still unknown. We hypothesized that autoimmunity against components of the vascular wall might play a critical role in sCAD and examined anti-collagen type I antibodies in patients with sCAD, acute ischemic stroke, patients with thromboendarterectomy, and controls. Methods: Fifty-seven patients with sCAD (age 45.7 ± 10.2 years, female 18 (31.6%)) were prospectively enrolled in four German stroke centers. Blood samples were collected at baseline, at day 10 ± 3, and after 6 ± 1 months. Patients with ischemic stroke not related to CAD (n=54, age 56.7 ± 13.7 years, female 15 (27.8%)), healthy probands (n=80, age 57.4 ± 12.9 years, female 56 (70%)), and patients undergoing thromboendarterectomy of the carotid artery (n=9, age 70.7 ± 9.3 years, female 2 (22.2%)) served as controls. Anti-collagen type I antibodies were determined by enzyme-linked immunosorbent assays (ELISAs). Results: Patients with acute sCAD had higher serum levels of anti-collagen type I antibodies (33.9 ± 24.6 µg/ml) than probands (18.5 ± 11.0 µg/ml; p <0.001) but lower levels than patients with ischemic stroke not related to sCAD (47.8 ± 28.4 µg/ml; p=0.003). In patients with sCAD, serum levels of anti-collagen type I antibodies were similar in the acute, subacute, and chronic phase. Levels of anti-collagen type I antibodies significantly correlated with circulating collagen type I (rho=0.207, p=0.003). Conclusion: Anti-collagen type I antibodies seem not to represent a trigger for acute sCAD or ischemic stroke but may rather be linked to the metabolism and turnover of collagen type I.

The immunomodulatory mechanism of acupuncture treatment for ischemic stroke: research progress, prospects, and future direction.

Ischemic stroke (IS) is one of the leading causes of death and disability. Complicated mechanisms are involved in the pathogenesis of IS. Immunomodulatory mechanisms are crucial to IS. Acupuncture is a traditional non-drug treatment that has been extensively used to treat IS. The exploration of neuroimmune modulation will broaden the understanding of the mechanisms underlying acupuncture treatment. This review summarizes the immune response of immune cells, immune cytokines, and immune organs after an IS. The immunomodulatory mechanisms of acupuncture treatment on the central nervous system and peripheral immunity, as well as the factors that influence the effects of acupuncture treatment, were summarized. We suggest prospects and future directions for research on immunomodulatory mechanisms of acupuncture treatment for IS based on current progress, and we hope that these will provide inspiration for researchers. Additionally, acupuncture has shown favorable outcomes in the treatment of immune-based nervous system diseases, generating new directions for research on possible targets and treatments for immune-based nervous system diseases.

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 anti­inflammatory 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.

Ischemic stroke outcome after promoting CD4+CD25+ Treg cell migration through CCR4 overexpression in a tMCAO animal model.

The importance of neuroinflammation during the ischemic stroke has been extensively studied. The role of CD4+CD25+ regulatory T (Treg) cells during the recovery phase have shown infarct size reduction and functional improvement, possibly through the mitigation of inflammatory immune responses. We aimed to investigate the molecular factors involved in microglia-Treg cell communication that result in Treg trafficking. First, we observed the migration patterns of CD8+ (cytotoxic) T cells and Treg cells and then searched for chemokines released by activated microglia in an oxygen-glucose deprivation (OGD) model. The transwell migration assay showed increased migration into OGD media for both cell types, in agreement with the increase in chemokines involved in immune cell trafficking from the mouse chemokine profiling array. MSCV retrovirus was transduced to overexpress CCR4 in Treg cells. CCR4-overexpressed Treg cells were injected into the mouse transient middle cerebral artery occlusion (tMCAO) model to evaluate the therapeutic potential via the tetrazolium chloride (TTC) assay and behavioral tests. A general improvement in the prognosis of animals after tMCAO was observed. Our results suggest the increased mobility of CCR4-overexpressed Treg cells in response to microglia-derived chemokines in vitro and the therapeutic potential of Treg cells with increased mobility in cellular therapy.

Systemic immune-inflammation index upon admission correlates to post-stroke cognitive impairment in patients with acute ischemic stroke.

BACKGROUND: The purpose of this prospective study was to evaluate the association of systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI), with PSCI in patients with acute ischemic stroke (AIS). METHODS: First-onset AIS patients were consecutively included from January 1, 2022 to March 1, 2023. The baseline information was collected at admission. Fasting blood was drawn the next morning. Cognitive function was assessed by the Montreal Cognitive Assessment (MoCA) 3 months after onset. Logistic regression analysis was performed to explore the correlation between SII, SIRI, and PSCI. Receiver operating characteristic (ROC) was conducted to evaluate the predictive ability of SII. RESULTS: 332 participants were recruited, and 193 developed PSCI. Compared with patients without PSCI, the patients with PSCI had higher SII (587.75 (337.42, 988.95) vs. 345.66 (248.44, 572.89), P<0.001) and SIRI (1.59 (0.95, 2.84) vs. 1.02 (0.63, 1.55), P=0.007). SII and SIRI negatively correlated with MoCA scores (both P<0.05). The multivariable logistic regression analysis indicated that SII was independently associated with PSCI (P<0.001), while SIRI was not. The optimal cutoff for SII to predict PSCI was 676.83×109/L. CONCLUSIONS: A higher level of SII upon admission was independently correlated to PSCI three months later in AIS patients.

Seipin is involved in oxygen-glucose deprivation/reoxygenation induced neuroinflammation by regulating the TLR3/TRAF3/NF-κB pathway.

Seipin plays a crucial role in lipid metabolism and is involved in neurological disorders. However, the function and mechanism of action of seipin in acute ischemic stroke have not yet been elucidated. Here, we aimed to investigate the effect of seipin on neuroinflammation induced by oxygen-glucose deprivation/reoxygenation (OGD/R) and further explore the molecular mechanism by functional experiments. Our results revealed a significant decrease in seipin mRNA levels, accompanied by enhanced expression of TNF-α in patients with AIS, and a significant negative correlation between seipin and TNF-α was observed. Additionally, there was a negative correlation between seipin levels and the National Institutes of Health Stroke Scale (NIHSS) score. Furthermore, seipin levels were also decreased in middle cerebral artery occlusion/reperfusion (MCAO/R) mice and OGD/R-treated BV2 cells. RNA sequencing analysis showed that seipin knockdown altered the Toll-like receptor 3 (TLR3) signaling pathway. It was further confirmed in vitro that seipin knockdown caused significantly increased secretion of inflammatory factors including TNF-α, interleukin (IL)-1ß, and interferon (IFN)-ß. Meanwhile, seipin knockdown activated the Tlr3 signal pathway while this effect could be reversed by Tlr3 inhibitor in OGD/R treated BV2 cells. Furthermore, neuroinflammation induced by OGD/R was significantly reduced by seipin overexpression. Overall, our study demonstrate that seipin deficiency aggravates neuroinflammation by activating the TLR3/TRAF3/NF-κB signaling pathway after OGD/R stimuli, and suggest that seipin may be a potential therapeutic target for AIS.

Peripheral inflammation and trajectories of depressive symptomology after ischemic stroke: A prospective cohort study.

BACKGROUND: Understanding the association of peripheral inflammation and post-stroke depressive symptomology (PSDS) might provide further insights into the complex etiological mechanism of organic depression. However, studies focusing on the longitudinal patterns of PSDS were limited and it remained unclear whether peripheral inflammation influences the occurrence and development of PSDS. METHODS: A total of 427 prospectively enrolled and followed ischemic stroke patients were included in the analytical sample. Depressive symptomology was assessed on four occasions during 1 year after ischemic stroke. Peripheral inflammatory proteins on admission and repeated measures of peripheral immune markers in three stages were collected. Latent class growth analysis (LCGA) was employed to delineate group-based trajectories of peripheral immune markers and PSDS. Multinomial regression was performed to investigate the association of peripheral inflammation with PSDS trajectories. RESULTS: Four distinct trajectories of PSDS were identified: stable-low (n = 237, 55.5 %), high-remitting (n = 120, 28.1 %), late-onset (n = 44, 10.3 %), and high-persistent (n = 26, 6.1 %) PSDS trajectories. The elevation of peripheral fibrinogen on admission increased the risk of high-persistent PSDS in patients with early high PSDS. Additionally, chronic elevation of innate immune levels might not only increase the risk of high-persistent PSDS in patients with early high PSDS but also increase the risk of late-onset PSDS in patients without early high PSDS. The elevation of adaptive immune levels in the convalescence of ischemic stroke may contribute to the remission of early high PSDS. CONCLUSIONS: Peripheral immunity could influence the development of PSDS, and this influence might have temporal heterogeneity. These results might provide vital clues for the inflammation hypothesis of PSD.

Systemic immune-inflammation index is associated with cardiac complications following acute ischemic stroke: A retrospective single-center study.

BACKGROUND: Stroke-induced heart syndrome is a feared complication of ischemic stroke, that is commonly encountered and has a strong association with unfavorable prognosis. More research is needed to explore underlying mechanisms and inform clinical decision making. This study aims to explore the relationship between the early systemic immune-inflammation (SII) index and the cardiac complications after acute ischemic stroke. METHODS: Consecutive patients with acute ischemic stroke were prospectively collected from January 2020 to August 2022 and retrospectively analyzed. We included subjects who presented within 24 hours after symptom onset and were free of detectable infections or cancer on admission. SII index [(neutrophils × platelets/ lymphocytes)/1000] was calculated from laboratory data at admission. RESULTS: A total of 121 patients were included in our study, of which 24 (19.8 %) developed cardiac complications within 14 days following acute ischemic stroke. The SII level was found higher in patients with stroke-heart syndrome (p<.001), which was an independent predictor of stroke-heart syndrome (adjusted odds ratio 5.089, p=.002). CONCLUSION: New-onset cardiovascular complications diagnosed following a stroke are very common and are associated with early SII index.

Targeting pyroptosis to treat ischemic stroke: From molecular pathways to treatment strategy.

Ischemic stroke is the primary reason for human disability and death, but the available treatment options are limited. Hence, it is imperative to explore novel and efficient therapies. In recent years, pyroptosis (a pro-inflammatory cell death characterized by inflammation) has emerged as an important pathological mechanism in ischemic stroke that can cause cell death through plasma membrane rupture and release of inflammatory cytokines. Pyroptosis is closely associated with inflammation, which exacerbates the inflammatory response in ischemic stroke. The level of inflammasomes, GSDMD, Caspases, and inflammatory factors is increased after ischemic stroke, exacerbating brain injury by mediating pyroptosis. Hence, inhibition of pyroptosis can be a therapeutic strategy for ischemic stroke. In this review, we have summarized the relationship between pyroptosis and ischemic stroke, as well as a series of treatments to attenuate pyroptosis, intending to provide insights for new therapeutic targets on ischemic stroke.

M6A-related bioinformatics analysis indicates that LRPPRC is an immune marker for ischemic stroke.

Ischemic stroke (IS) is a common cerebrovascular disease whose pathogenesis involves a variety of immune molecules, immune channels and immune processes. 6-methyladenosine (m6A) modification regulates a variety of immune metabolic and immunopathological processes, but the role of m6A in IS is not yet understood. We downloaded the data set GSE58294 from the GEO database and screened for m6A-regulated differential expression genes. The RF algorithm was selected to screen the m6A key regulatory genes. Clinical prediction models were constructed and validated based on m6A key regulatory genes. IS patients were grouped according to the expression of m6A key regulatory genes, and immune markers of IS were identified based on immune infiltration characteristics and correlation. Finally, we performed functional enrichment, protein interaction network analysis and molecular prediction of the immune biomarkers. We identified a total of 7 differentially expressed genes in the dataset, namely METTL3, WTAP, YWHAG, TRA2A, YTHDF3, LRPPRC and HNRNPA2B1. The random forest algorithm indicated that all 7 genes were m6A key regulatory genes of IS, and the credibility of the above key regulatory genes was verified by constructing a clinical prediction model. Based on the expression of key regulatory genes, we divided IS patients into 2 groups. Based on the expression of the gene LRPPRC and the correlation of immune infiltration under different subgroups, LRPPRC was identified as an immune biomarker for IS. GO enrichment analyses indicate that LRPPRC is associated with a variety of cellular functions. Protein interaction network analysis and molecular prediction indicated that LRPPRC correlates with a variety of immune proteins, and LRPPRC may serve as a target for IS drug therapy. Our findings suggest that LRPPRC is an immune marker for IS. Further analysis based on LRPPRC could elucidate its role in the immune microenvironment of IS.

Discovery and validation of molecular patterns and immune characteristics in the peripheral blood of ischemic stroke patients.

Background: Stroke is a disease with high morbidity, disability, and mortality. Immune factors play a crucial role in the occurrence of ischemic stroke (IS), but their exact mechanism is not clear. This study aims to identify possible immunological mechanisms by recognizing immune-related biomarkers and evaluating the infiltration pattern of immune cells. Methods: We downloaded datasets of IS patients from GEO, applied R language to discover differentially expressed genes, and elucidated their biological functions using GO, KEGG analysis, and GSEA analysis. The hub genes were then obtained using two machine learning algorithms (least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE)) and the immune cell infiltration pattern was revealed by CIBERSORT. Gene-drug target networks and mRNA-miRNA-lncRNA regulatory networks were constructed using Cytoscape. Finally, we used RT-qPCR to validate the hub genes and applied logistic regression methods to build diagnostic models validated with ROC curves. Results: We screened 188 differentially expressed genes whose functional analysis was enriched to multiple immune-related pathways. Six hub genes (ANTXR2, BAZ2B, C5AR1, PDK4, PPIH, and STK3) were identified using LASSO and SVM-RFE. ANTXR2, BAZ2B, C5AR1, PDK4, and STK3 were positively correlated with neutrophils and gamma delta T cells, and negatively correlated with T follicular helper cells and CD8, while PPIH showed the exact opposite trend. Immune infiltration indicated increased activity of monocytes, macrophages M0, neutrophils, and mast cells, and decreased infiltration of T follicular helper cells and CD8 in the IS group. The ceRNA network consisted of 306 miRNA-mRNA interacting pairs and 285 miRNA-lncRNA interacting pairs. RT-qPCR results indicated that the expression levels of BAZ2B, C5AR1, PDK4, and STK3 were significantly increased in patients with IS. Finally, we developed a diagnostic model based on these four genes. The AUC value of the model was verified to be 0.999 in the training set and 0.940 in the validation set. Conclusion: Our research explored the immune-related gene expression modules and provided a specific basis for further study of immunomodulatory therapy of 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.

Machine learning identifies novel coagulation genes as diagnostic and immunological biomarkers in ischemic stroke.

BACKGROUND: Coagulation system is currently known associated with the development of ischemic stroke (IS). Thus, the current study is designed to identify diagnostic value of coagulation genes (CGs) in IS and to explore their role in the immune microenvironment of IS. METHODS: Aberrant expressed CGs in IS were input into unsupervised consensus clustering to classify IS subtypes. Meanwhile, key CGs involved in IS were further selected by weighted gene co-expression network analysis (WGCNA) and machine learning methods, including random forest (RF), support vector machine (SVM), generalized linear model (GLM) and extreme-gradient boosting (XGB). The diagnostic performance of key CGs were evaluated by receiver operating characteristic (ROC) curves. At last, quantitative PCR (qPCR) was performed to validate the expressions of key CGs in IS. RESULTS: IS patients were classified into two subtypes with different immune microenvironments by aberrant expressed CGs. Further WGCNA, machine learning methods and ROC curves identified ACTN1, F5, TLN1, JMJD1C and WAS as potential diagnostic biomarkers of IS. In addition, their expressions were significantly correlated with macrophages, neutrophils and/or T cells. GSEA also revealed that those biomarkers may regulate IS via immune and inflammation. Moreover, qPCR verified the expressions of ACTN1, F5 and JMJD1C in IS. CONCLUSIONS: The current study identified ACTN1, F5 and JMJD1C as novel coagulation-related biomarkers associated with IS immune microenvironment, which enriches our knowledge of coagulation-mediated pathogenesis of IS and sheds light on next-step in vivo and in vitro experiments to elucidate the relevant molecular mechanisms.

Ischemic stroke and diabetes: a TLR4-mediated neuroinflammatory perspective.

Ischemic stroke is the major contributor to morbidity and mortality in people with diabetes mellitus. In ischemic stroke patients, neuroinflammation is now understood to be one of the main underlying mechanisms for cerebral damage and recovery delay. It has been well-established that toll-like receptor 4 (TLR4) signaling pathway plays a key role in neuroinflammation. Emerging research over the last decade has revealed that, compared to ischemic stroke without diabetes mellitus, ischemic stroke with diabetes mellitus significantly upregulates TLR4-mediated neuroinflammation, increasing the risk of cerebral and neuronal damage as well as neurofunctional recovery delay. This review aims to discuss how ischemic stroke with diabetes mellitus amplifies TLR4-mediated neuroinflammation and its consequences. Additionally covered in this review is the potential application of TLR4 antagonists in the management of diabetic ischemic stroke.

A Neutrophil Hijacking Nanoplatform Reprograming NETosis for Targeted Microglia Polarizing Mediated Ischemic Stroke Treatment.

Precise and efficient regulation of microglia is vital for ischemic stroke therapy and prognosis. The infiltration of neutrophils into the brain provides opportunities for regulatory drugs across the blood-brain barrier, while hindered by neutrophil extracellular traps (NETs) and targeted delivery of intracerebral drugs to microglia. This study reports an efficient neutrophil hijacking nanoplatform (referred to as APTS) for targeted A151 (a telomerase repeat sequence) delivery to microglia without the generation of NETs. In the middle cerebral artery occlusion (MCAO) mouse model, the delivery efficiency to ischemic stroke tissues increases by fourfold. APTS dramatically reduces the formation of NETs by 2.2-fold via reprogramming NETosis to apoptosis in neutrophils via a reactive oxygen species scavenging-mediated citrullinated histone 3 inhibition pathway. Noteworthy, A151 within neutrophils is repackaged into apoptotic bodies following the death pattern reprogramming, which, when engulfed by microglia, polarizes microglia to an anti-inflammatory M2 phenotype. After four times treatment, the cerebral infarction area in the APTS group decreases by 5.1-fold. Thus, APTS provides a feasible, efficient, and practical drug delivery approach for reshaping the immune microenvironment and treating brain disorders in the central nervous system.

Brain-associated innate leukocytes display diverse inflammatory states following experimental stroke.

Previous studies investigating innate leukocyte recruitment into the brain after cerebral ischemia have shown conflicting results. Using distinct cell surface and intracellular markers, the current study evaluated the contributions of innate immune cells to the poststroke brain following 1-h middle cerebral artery occlusion (tMCAO) or permanent MCAO (pMCAO), and assessed whether these cells ascribed to an inflammatory state. Moreover, we examined whether there is evidence for leukocyte infiltration into the contralateral (CL) hemisphere despite the absence of stroke infarct. We observed the recruitment of peripheral neutrophils, monocytes and macrophages into the hemisphere ipsilateral (IL) to the ischemic brain infarct at 24 and 96 h following both tMCAO and pMCAO. In addition, we found evidence of increased leukocyte recruitment to the CL hemisphere but to a lesser extent than the IL hemisphere after stroke. Robust production of intracellular cytokines in the innate immune cell types examined was most evident at 24 h after pMCAO. Specifically, brain-associated neutrophils, monocytes and macrophages demonstrated stroke-induced production of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1ß, while only monocytes and macrophages exhibit a significant expression of arginase 1 (Arg1) after stroke. At 96 h after stroke, brain-resident microglia demonstrated production of TNF-α and IL-1ß following both tMCAO and pMCAO. At this later timepoint, neutrophils displayed TNF-α production and brain-associated macrophages exhibited elevation of IL-1ß and Arg1 after tMCAO. Further, pMCAO induced significant expression of Arg1 and IL-1ß in monocytes and macrophages at 96 h, respectively. These results revealed that brain-associated innate immune cells display various stroke-induced inflammatory states that are dependent on the experimental stroke setting.

Irisin Protects Cerebral Neurons from Hypoxia/Reoxygenation via Suppression of Apoptosis and Expression of Pro-Inflammatory Cytokines.

BACKGROUND: Ischemic stroke is a major health issue that causes high incidents of morbidity and mortality worldwide. Irisin is an excise-induced protein that has exhibited pleiotropic properties. Accumulating evidence reveals its critical roles in the regulation of various cellular functions, including nervous system functions. This study aims to disclose the effect of irisin on rat cerebral neurons suffering from hypoxia/reoxygenation (H/R) treatment and to explore the potential underlying molecular mechanisms. METHODS: The percentage of rat cerebral neuron cell death was determined by flow cytometry analysis and MTT assay. The expression levels of target genes were measured by western blotting and real-time quantitative reverse transcription PCR assay. RESULTS: Our results demonstrated that irisin treatment substantially reduced H/R-induced apoptosis of rat cerebral neurons. Further investigation revealed that irisin treatment markedly decreased mitogen-activated protein kinase (MAPK) signaling pathway activation and suppressed pro-informatory cytokine expression in cerebral neurons with H/R challenge. Finally, we showed that the neuroprotective effect and anti-inflammatory effect of irisin were comparable with three MAPK signaling inhibitors. CONCLUSION: Irisin exerts profound neuroprotective and anti-inflammatory effects on H/R-stimulated cerebral neurons by inhibiting the MAPK signaling activation. Therefore, irisin may serve as a potential drug for the treatment of patients with ischemic stroke.