Global brain inflammation in stroke

Mechanisms Associated with Mitophagy and Ferroptosis in Cerebral Ischemia-reperfusion Injury

Ischemic stroke (IS) constitutes a major threat to human health. Vascular recanalization by intravenous thrombolysis and mechanical thrombolysis remain the most significant and effective methods for relief of ischemia. Key elements of these treatments include achieving blood-vessel recanalization, restoring brain-tissue reperfusion, and preserving the ischemic penumbra. However, in achieving the therapeutic goals of vascular recanalization, secondary damage to brain tissue from cerebral ischemia-reperfusion injury (CIRI) must also be addressed. Despite advancements in understanding the pathological processes associated with CIRI, effective interventions to prevent its onset and progression are still lacking. Recent research has indicated that mitophagy and ferroptosis are critical mechanisms in the development of CIRI, and significantly contribute to the onset and progression of IS and CIRI because of common targets and co-occurrence mechanisms. Therefore, exploring and summarizing the potential connections between mitophagy and ferroptosis during CIRI is crucial. In the present review, we mainly focused on the mechanisms of mitochondrial autophagy and ferroptosis, and their interaction, in the development of CIRI. We believe that the data show a strong relationship between mitochondrial autophagy and ferroptosis with interactive regulation. This information may underpin new potential approaches for the prevention and treatment of IS and subsequent CIRI.

T cell receptor activation contributes to brain damage after intracerebral hemorrhage in mice

BACKGROUND

Our previous studies demonstrated that activated T cells accumulate in perihematomal regions following intracerebral hemorrhage (ICH) and exacerbate hemorrhagic brain injury. In the present study, we aimed to explore the mechanisms underlying brain-infiltrating T cell activation and the associated pathophysiological effects in neurological outcomes following ICH.

METHODS

We employed standardized collagenase injection-induced and autologous blood injection models of ICH in male C57BL/6J mice. T cell receptor (TCR) activation, immune cell infiltration, and cytokine production were quantified through immunostaining, flow cytometry, and cytokine arrays at 1- and 3-days post-ICH. Brain edema volume was measured at 3 days post-ICH and neurobehavioral assessments were conducted up to 14 days post-ICH. Pharmacological inhibition of TCR activation was achieved using the TCR-specific inhibitor AX-024, administered intraperitoneally at a dosage of 10 mg/kg 1-hour post-ICH.

RESULTS

Flow cytometry and immunostaining detected TCR activation of brain-infiltrating T cells. Specific TCR activation inhibitor AX-024 administration markedly reduced TCR activation and the production of pro-inflammatory cytokines in the brain at 1- and 3-days post-ICH. Moreover, AX-024 administration led to a significant reduction in the infiltration of other leukocyte populations, and significantly reduced brain edema while improved long-term sensorimotor and cognitive outcomes up to 14 days post-ICH.

DISCUSSION

Our findings underscore the critical role of TCR activation in the mobilization and activation of brain-infiltrating T cells post-ICH. Inhibition of TCR activation via AX-024 administration might be developed as a promising therapeutic strategy to improve neurological outcomes following ICH. However, further research is necessary to thoroughly explore the complex pathophysiological processes involved.

Novel Hypochlorous Acid-Activated Near-Infrared Probe Monitors the Dynamic Changes of Myeloperoxidase Activity in Ischemic Brain

Myeloperoxidase (MPO) contributes to the progression of ischemic damage. To fully understand MPO biology, highly sensitive and specific probes that can trace the activity of endogenous MPO fluxes are indispensable. Here, we developed two hypochlorous acid (HClO)-activated near-infrared probes to image MPO activity in a noninvasive manner. The probe MPO-NIR-II could track MPO-induced HClO in real time and in situ upon various stimuli with high sensitivity and specificity. Furthermore, MPO-NIR-II could monitor the MPO activity by in vivo fluorescence imaging and confocal laser scanning microscopy in mice with ischemic stroke. Moreover, a high-content screening system for MPO inhibitors was established by combining MPO-NIR-II with MPO-overexpressed cells and mouse brain slices with ischemic stroke, and the candidate compound AZD5904 was found to effectively attenuate ischemic brain injury. Overall, this work provides a versatile fluorescence tool that holds great promise for visualizing endogenous MPO fluxes of brain ischemia.

Regulation of macrophage efferocytosis by the CLCF1/NF-κB pathway improves neurological and cognitive impairment following CO poisoning

Severe carbon monoxide (CO) poisoning can induce structural and functional damage to the nervous system, resulting in persistent cognitive impairments. Properly terminating inflammation caused by neuronal damage is essential for tissue repair. Macrophages clear cell corpses and fragments through efferocytosis and produce cytokines to coordinate the immune response, thus promoting neuronal repair and regeneration. However, within the microenvironment of the CO-affected nervous system, macrophage efferocytosis is disrupted. Our study found that macrophages regulate efferocytosis by releasing Cardiotrophin-like cytokine factor 1 (CLCF1), which modulates the NF-κB pathway in both macrophages and microglia, thereby controlling inflammation and promoting nervous system repair. Furthermore, efferocytosis regulates the secretion of cytokines such as TNF-α, IL-1β, and IL-10, promoting M2 polarization of macrophages, which aids in neuronal repair and regeneration. Regulating macrophage CLCF1 expression also leads to improvements in the memory, learning, and motor abilities of rats poisoned with CO.

Post-stroke depression: exploring gut microbiota-mediated barrier dysfunction through immune regulation

Post-stroke depression (PSD) is one of the most common and devastating neuropsychiatric complications in stroke patients, affecting more than one-third of survivors of ischemic stroke (IS). Despite its high incidence, PSD is often overlooked or undertreated in clinical practice, and effective preventive measures and therapeutic interventions remain limited. Although the exact mechanisms of PSD are not fully understood, emerging evidence suggests that the gut microbiota plays a key role in regulating gut-brain communication. This has sparked great interest in the relationship between the microbiota-gut-brain axis (MGBA) and PSD, especially in the context of cerebral ischemia. In addition to the gut microbiota, another important factor is the gut barrier, which acts as a frontline sensor distinguishing between beneficial and harmful microbes, regulating inflammatory responses and immunomodulation. Based on this, this paper proposes a new approach, the microbiota-immune-barrier axis, which is not only closely related to the pathophysiology of IS but may also play a critical role in the occurrence and progression of PSD. This review aims to systematically analyze how the gut microbiota affects the integrity and function of the barrier after IS through inflammatory responses and immunomodulation, leading to the production or exacerbation of depressive symptoms in the context of cerebral ischemia. In addition, we will explore existing technologies that can assess the MGBA and potential therapeutic strategies for PSD, with the hope of providing new insights for future research and clinical interventions.

Association between serum inflammatory cytokines levels and post-stroke depression among stroke patients: A meta-analysis and systematic review

BACKGROUND

Post-stroke depression (PSD) is a common neuropsychiatric complication after stroke. Neuroinflammation triggered by the stroke event may be its predisposing factor.

METHODS

We systematically searched all electronic databases up to December 22, 2024. Observational studies comparing cytokine levels between PSD and non-PSD patients were included. Sensitivity analysis, subgroup analysis, and meta-regression were conducted to assess robustness, explore heterogeneity, and identify effect modifiers.

RESULTS

A total of 26 studies with 6573 acute stroke patients were included, of whom 2453 developed PSD. PSD patients were older (63.7 vs. 62.8 years) and included more females (36.4 % vs. 35.1 %) than non-PSD patients. PSD patients had significantly higher serum levels of IL-1β (SMD = 0.35, 95 % CI = [0.07, 0.63], p = 0.02), IL-6 (SMD = 0.74, 95 % CI = [0.50, 0.97], p < 0.001), IL-18 (SMD = 0.49, 95% CI = [0.13, 0.86], p = 0.007), TNF-α (SMD = 0.44, 95 % CI = [0.15, 0.72], p = 0.003) and IFN-γ (SMD = 0.11, 95 % CI = [0.02, 0.19], p = 0.01), while IL-10 levels showed no significant difference (p = 0.06). IL-6 levels remained associated with PSD diagnosis at 1, 3 and 6 months. Meta-regression identified female proportion (IL-6: p = 0.043; IL-10: p = 0.024), mean age (IL-18: p = 0.015; TNF-α: p = 0.040), BMI (IL-18: p = 0.019), and diabetes proportion (IL-6: p = 0.009; TNF-α: p = 0.033) as significant moderators.

CONCLUSIONS

Inflammatory cytokines may serve as biomarkers for PSD, offering insights into its pathophysiology and potential diagnostic tools. Prospero registration number: CRD42024548753.

Sex-specific cognitive benefits and anti-inflammatory effects of coumestrol pretreatment in transient global cerebral ischemia

Cerebral Global Ischemia (CGI) is a devastating neurological condition affecting millions globally each year, leading to significant inflammatory responses and long-term consequences, including delayed neuronal death and neurocognitive impairment. Following brain injury, resident microglial cells are activated, triggering pro-inflammatory cytokine expression and altering neuroimmune processes in a sex-dependent manner, particularly within the hippocampus. Coumestrol, a plant estrogen, is promoted as an alternative to post-menopausal hormone therapy due to its various mechanisms that enhance brain health, including its anti-inflammatory effects. This study aimed to investigate whether coumestrol pretreatment could attenuate the neuroinflammatory response following CGI by regulating pro-inflammatory pathways (GFAP, S100B, TNF-α, and IL-1β) and reversing CGI-induced memory loss. Male and female rats underwent CGI for 10 min or a sham surgery and received an ICV infusion of 20 μg of coumestrol or vehicle 1 h before CGI induction. Our findings revealed intriguing sex-specific effects of coumestrol pretreatment on gliosis following CGI and reperfusion, suggesting modulation of glial responses after ischemic insults. Coumestrol pre-administration significantly reduced levels of pro-inflammatory cytokines TNF-α and IL-1β during both reperfusion periods in both sexes, thereby mitigating CGI-induced neuroinflammation. Moreover, coumestrol pretreatment effectively reduced stroke-induced cognitive impairment, alleviating ischemia-induced memory deficits in both male and female rats. These results demonstrate the coumestrol's ability to attenuate cognitive deficits induced by CGI and highlight its potential sex-specific effects on inflammatory pathways. This study suggests that coumestrol modulates the glial and microglial inflammatory response, offering a promising approach to mitigate memory deficits associated with cerebral global ischemia.

Redesigned chondroitinase ABC degrades inhibitory chondroitin sulfate proteoglycans in vitro and in vivo in the stroke-injured rat brain

Injuries to the central nervous system, such as stroke and traumatic spinal cord injury, result in an aggregate scar that both limits tissue degeneration and inhibits tissue regeneration. The aggregate scar includes chondroitin sulfate proteoglycans (CSPGs), which impede cell migration and axonal outgrowth. Chondroitinase ABC (ChASE) is a potent yet fragile enzyme that degrades CSPGs, and thus may enable tissue regeneration. ChASE37, with 37-point mutations to the native enzyme, has been shown to be more stable than ChASE, but its efficacy has never been tested. To answer this question, we investigated the efficacy of ChASE37 first in vitro using human cell-based assays and then in vivo in a rodent model of stroke. We demonstrated ChASE37 degradation of CSPGs in vitro and the consequent cell adhesion and axonal sprouting now possible using human induced pluripotent stem cell (hiPSC)-derived neurons. To enable prolonged release of ChASE37 to injured tissue, we expressed it as a fusion protein with a Src homology 3 (SH3) domain and modified an injectable, carboxymethylcellulose (CMC) hydrogel with SH3-binding peptides (CMC-bp) using inverse electron-demand Diels-Alder chemistry. We injected this affinity release CMC-bp/SH3-ChASE37 hydrogel epicortically to endothelin-1 stroke-injured rats and confirmed bioactivity via degradation of CSPGs and axonal sprouting in and around the lesion. With CSPG degradation shown both in vitro by greater cell interaction and in vivo with local delivery from a sustained release formulation, we lay the foundation to test the potential of ChASE37 and its delivery by local affinity release for tissue regeneration after stroke.

Fluid excess on intensive care unit after mechanical thrombectomy after acute ischemic stroke is associated with unfavorable neurological and functional outcomes: An observational cohort study

INTRODUCTION

Endovascular thrombectomy stands as a pivotal component in the standard care for patients experiencing acute ischemic stroke with large vessel occlusion. Subsequent care for patients often extends to a neurological intensive care unit. While fluid management is integral to intensive care, the association between early fluid balance and neurological and functional outcomes post-thrombectomy has not yet been thoroughly investigated.

METHODS

In a retrospective analysis of an observational, single-center study spanning from 2015 to 2021 at the University Medical Center Hamburg-Eppendorf, Germany, we enrolled stroke patients who underwent thrombectomy and received subsequent treatment in the ICU. Unfavorable functional and neurological outcome was defined as a mRS > 2 on day 90 after admission (mRS d90) or NIHSS > 5 at discharge, respectively. A multivariate regression model, adjusting for confounders, utilized the average fluid balance in the first 5 days to predict outcomes. Patients were dichotomized by their average fluid balance (>1 L vs <1 L) within the first 5 days, and a multivariate mRS d90 shift analysis was conducted after adjusting for covariates.

RESULTS

Between 2015 and 2021, 1252 patients underwent thrombectomy, and 553 patients met the inclusion criteria (299 women [54%]). Unfavorable functional outcome was significantly associated with a higher daily average fluid balance in the first 5 days in the ICU (mRS d90 ⩽ 2: 0.3 ± 0.5 L, mRS d90 > 2: 0.7 ± 0.7 L, p = 0.02). The same association was observed for the NIHSS at discharge (NIHSS ⩽ 5: 0.3 ± 0.5 L; NIHSS > 5: 0.6 ± 0.6 L; p = 0.03). The mRS d90 shift analysis revealed significance for patients with an average fluid balance <1 L for better functional outcomes (adjusted odds ratio [AOR] 2.17; 95% confidence interval [CI] 1.54-3.07; p < 0.01).

DISCUSSION

Fluid retention in post-thrombectomy stroke patients in the ICU is associated with poorer functional and neurological outcomes. Consequently, fluid retention emerges as an additional potential predictor for post-intervention stroke outcomes. Our findings provide an initial indication that preventing excessive fluid retention in stroke patients after endovascular thrombectomy could be beneficial for both functional and neurological recovery. Therefore, fluid retention might be an element to consider in optimizing fluid management for stroke patients.

Traditional Chinese Medicine Borneol-Based Polymeric Micelles Intracerebral Drug Delivery System for Precisely Pathogenesis-Adaptive Treatment of Ischemic Stroke

The scarcity of effective neuroprotective agents and the presence of blood-brain barrier (BBB)-mediated extremely inefficient intracerebral drug delivery are predominant obstacles to the treatment of cerebral ischemic stroke (CIS). Herein, ROS-responsive borneol-based amphiphilic polymeric NPs are constructed by using traditional Chinese medicine borneol as functional blocks that served as surface brain-targeting ligand, inner hydrophobic core for efficient drug loading of membrane-permeable calcium chelator BAPTA-AM, and neuroprotective structural component. In MCAO mice, the nanoformulation (polymer: 3.2 mg·kg-1, BAPTA-AM: 400 µg·kg-1) reversibly opened the BBB and achieved high brain biodistribution up to 12.7%ID/g of the total administered dose after 3 h post single injection, effectively restoring intracellular Ca2+ and redox homeostasis, improving cerebral histopathology, and inhibiting mitochondrial PI3K/Akt/Bcl-2/Bax/Cyto-C/Caspase-3,9 apoptosis pathway for rescuing dying neurons (reduced apoptosis cell from 59.5% to 7.9%). It also remodeled the inflammatory microenvironment in cerebral ischemic penumbra by inhibiting astrocyte over-activation, reprogramming microglia polarization toward an anti-inflammatory phenotype, and blocking NF-κB/TNF-α/IL-6 signaling pathways. These interventions eventually reduced the cerebral infarction area by 96.3%, significantly improved neurological function, and restored blood flow reperfusion from 66.2% to ≈100%, all while facilitating BBB repair and avoiding brain edema. This provides a potentially effective multiple-stage sequential treatment strategy for clinical CIS.

Recovery of activation propagation and self-sustained oscillation abilities in stroke brain networks

Healthy brain networks usually show highly efficient information communication and self-sustained oscillation abilities. However, how the brain network structure affects these dynamics after an injury (stroke) is not very clear. The recovery of structure and dynamics of stroke brain networks over time is still not known precisely. Based on the analysis of a large number of strokes' brain network data, we show that stroke changes the network properties in connection weights, average degree, clustering, community, etc. Yet, they will recover gradually over time to some extent. We then adopt a simplified reaction-diffusion model to investigate stroke patients' activation propagation and self-sustained oscillation abilities. Our results reveal that the stroke slows the adoption time across different brain scales, indicating a weakened brain's activation propagation ability. In addition, we show that the lifetime of self-sustained oscillatory patterns at 3 months post-stroke, patients' brains significantly depart from the healthy ones. Finally, we examine the properties of core networks of self-sustained oscillatory patterns, in which the directed edges denote the main pathways of activation propagation. Our results demonstrate that the lifetime and recovery of self-sustaining patterns are related to the properties of core networks, and the properties in the post-stroke greatly vary from those in the healthy group. Most importantly, the strokes' activation propagation and self-sustained oscillation abilities significantly improve at 1 year post-stroke, driven by structural connection repair. This work may help us to understand the relationship between structure and function in brain disorders.

Deep Hypothermic Low Flow Results in Multiple Aspects of Neurological Deficits in Mice by eEF2 Hyperphosphorylation

Postoperative neurological dysfunction is a common complication caused by deep hypothermia with cerebral hypoperfusion during aortic arch surgery, but the exact pathological changes and molecular mechanisms are not yet clear. In this study, we established an adult mouse model of deep hypothermic low flow (DHLF) to simulate the ischemic-reperfusion brain injury during aortic arch surgery. The DHLF-modeled mice showed significant neurological and cognitive dysfunction, accompanied by reduced dendritic spine density and increased glial cell activation in the hippocampus and cortex. DHLF induced proteomic changes primarily involved in synaptic organization in the hippocampus and cortex, with AMPA and NMDA receptor subunits and synaptic activity-dependent proteins markedly downregulated in the hippocampus and/or cortex. Moreover, DHLF also resulted in altered proteome in mRNA translation and inhibition of eukaryotic elongation factor 2 (eEF2), a crucial regulator of translational elongation whose activity is negatively regulated via phosphorylation by eEF2 kinase (eEF2K). Importantly, the administration of the small-molecular eEF2K inhibitor A484954 ameliorated DHLF-induced neurobehavioral dysfunction, dendritic spine reduction, and glial cell activation, suggesting that eEF2K/eEF2 may be a promising therapeutic target in DHLF-induced neurological injury. Our findings revealed new evidence of pathological features, molecular mechanism, and intervention of DHLF-induced cerebral ischemia-reperfusion injury, providing promising insight for developing strategies on reducing postoperative neurological complications after aortic arch surgery.

The relationship between psychological distress and frailty in stroke patients: the mediating effect of depression

BACKGROUND

Frailty is a significant factor affecting the quality of life of stroke patients. psychological distress is an essential factor affecting depression in stroke patients. However, the mediating role of depression between psychological distress and debilitation has not been explored.

METHODS

In this study, 315 stroke patients in Shandong and Liaoning provinces were investigated by convenience sampling method from May 2024 to October 2024. Questionnaires included Frailty Scale and Psychological Distress and Depression scale.

RESULTS

In this study, psychological distress scores (4.16 ± 2.29), depression scores (8.81 ± 4.55) and frailty scores (8.92 ± 4.09) were obtained. There was a significant positive correlation between depression and psychological distress in stroke patients (r = 0.483, P < 0.001), depression and frailty (r = 0.575, P < 0.001). There was a significant positive correlation between psychological distress and frailty in stroke patients (r = 0.391, P < 0.001). The direct effect of psychological distress in stroke patients was 0.264. The direct mediating effect of depression on psychological distress and frailty was 0.435.

CONCLUSION

This study provides further insights into the psychological mechanism of psychological distress and frailty in stroke patients. Clinicians and nurses can actively help stroke patients reduce psychological distress, reduce the depression of stroke patients, so as to reduce the occurrence of frailty and improve the quality of life of patients.

Methylprednisolone as Adjunct to Thrombectomy for Acute Intracranial Internal Carotid Artery Occlusion Stroke: Post Hoc Secondary Analysis of the MARVEL Randomized Clinical Trial

Importance

Patients with acute ischemic stroke (AIS) due to intracranial internal carotid artery (ICA) occlusion often have poor functional outcomes despite undergoing endovascular thrombectomy (EVT).

Objective

To investigate the effectiveness and safety associated with intravenous methylprednisolone as adjunctive treatment to EVT for patients with AIS due to intracranial ICA occlusion.

Design, Setting, and Participants

This was a post hoc analysis of the MARVEL randomized, double-blind, placebo-controlled clinical trial conducted from February 9, 2022, to June 30, 2023, at 82 stroke centers across China with a 3-month follow-up. The primary trial enrolled 1680 patients with large vessel occlusion within 24 hours from last known well time in the intracranial ICA, the first segment of the middle cerebral artery (M1), or the second segment of the middle cerebral artery (M2), of whom 579 patients had intracranial ICA occlusion.

Intervention

Intravenous methylprednisolone, 2 mg/kg/d (maximum dose, 160 mg) for 3 days plus EVT vs placebo plus EVT.

Main Outcomes and Measures

The primary outcome was independent ambulation at 90 days, defined as a score of 0 to 3 on the modified Rankin Scale (range, 0 [no symptoms] to 6 [death]). Safety outcomes included death within 90 days, symptomatic intracranial hemorrhage (sICH) within 48 hours, and decompressive hemicraniectomy to relieve midline-shift and intracranial pressure after EVT.

Results

Among 579 patients (median age, 69.0 years [IQR, 59.0-76.0 years]; 338 men [58.4%]), there were 286 patients in the methylprednisolone group and 293 patients in the placebo group. The proportion of patients who achieved 90-day independent ambulation was significantly higher in the methylprednisolone group than in the placebo group (151 of 284 [53.2%] vs 125 of 293 [42.7%]; adjusted risk ratio [RR], 1.27 [95% CI, 1.07-1.52]; P = .007). The incidence of sICH was lower in the methylprednisolone group than in the placebo group (26 of 277 [9.4%] vs 45 of 290 [15.5%]; adjusted RR, 0.55 [95% CI, 0.35-0.87]; P = .01). The rate of decompressive hemicraniectomy was lower in the methylprednisolone group compared with the placebo group (16 of 286 [5.6%] vs 29 of 293 [9.9%]; adjusted RR, 0.54 [95% CI, 0.30-0.98]; P = .04). No significant difference was observed in mortality between groups (methylprednisolone, 92 of 284 [32.4%] vs placebo, 111 of 239 [37.9%]; adjusted RR, 0.84 [95% CI, 0.67-1.05]; P = .13).

Conclusions and Relevance

In this secondary analysis of a randomized clinical trial of intravenous methylprednisolone vs placebo for patients with intracranial ICA occlusion undergoing EVT, intravenous methylprednisolone was associated with improved ambulation. These findings suggest that the use of intravenous methylprednisolone as an adjunct to EVT may hold promise as a treatment option for patients with AIS due to intracranial ICA occlusion.

Trial registration

ChiCTR.org.cn Identifier: ChiCTR2100051729.

Relevance of peripheral inflammation indexes in different collateral circulation for intracranial hemorrhage in acute anterior circulation ischemic stroke patients undergoing endovascular treatment

BACKGROUND

Asymptomatic intracranial hemorrhage (aICH) is common after endovascular thrombectomy (EVT). Collateral circulation could modify the association between aICH with functional outcome and we aimed to investigate the impact of systemic inflammation index on 3-month outcome under different collateral circulation.

METHOD

Consecutive patients undertaken EVT were enrolled and classified into non-intracranial hemorrhage (non-ICH), aICH and symptomatic intracranial hemorrhage (sICH) groups according to the neurological status and National Institutes of Health Stroke Scale (NIHSS) changes within 72 hours after EVT. Preoperative collateral status was scored using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) scale. Clinical data were collected and analyzed according to the stratification of collateral stratification. Multivariate regression models were constructed to evaluate the influence of systemic inflammation indexes and collateral status on functional outcome.

RESULTS

Of 302 patients, 86 (28.5%) developed aICH with 36(11.9%) sICH. Compared to non-ICH patients, there was a significant trend towards higher proportion of poor collateral circulation in patients with aICH, sICH (47.8% vs. 67.2% vs. 94.4%, p <0.001). Spearman's correlation analysis revealed a significant negative correlation of peripheral neutrophil counts, NLR, and SIRI with collateral circulation score. Under poor collateral circulation, neutrophil counts showed a significant positive association with sICH (OR 1.20, 95%CI: 1.07-1.35, p=0.002), but not with aICH. Under good collateral circulation, the inflammation indexes did not show a significant correlation with either ICH.

CONCLUSION

aICH patients with good collateral circulation have good functional outcome comparable to no-ICH patients. Under poor collateral circulation, elevated neutrophil counts may contribute to the conversion from aICH to sICH. Tailored anti-inflammatory therapy has potential to improve the efficacy and safety of EVT.

The Role of Thrombo-inflammation in Ischemic Stroke: Focus on the Manipulation and Clinical Application

Stroke leaves a great economic burden due to its high morbidity and mortality. Rapid revascularization of targeted vessel(s) is the effective treatment for ischemic stroke, but subsequent ischemia-reperfusion (I/R) injury is a common complication following revascularization, leading to microcirculation dysfunction and infarct volume increase. Thrombo-inflammation, the interaction between thrombosis and inflammation, plays a critical role in the pathophysiology of ischemic stroke. In the context of I/R injury, thrombo-inflammation consists of platelet activation, endothelial injury, and inflammatory cell infiltration. Numerous studies are devoted to exploring methods of regulating thrombo-inflammation to mitigate I/R injury post-stroke, including blocking activations of platelets and neutrophils. Drugs such as antiplatelet medications, anticoagulants, and glucocorticoids have been confirmed to have the potential to regulate thrombo-inflammation. Furthermore, several recently developed drugs have also shown promises in relieving I/R injury by manipulating thrombo-inflammation. However, the majority of these studies are still in the preclinical stage. Herein, in this review, we will address the mechanisms of thrombo-inflammation in ischemic stroke, related research advances, and particularly the clinical feasibility of thrombo-inflammation as a therapeutic strategy against I/R injury.

High expression of ARPC1B promotes the proliferation and apoptosis of clear cell renal cell carcinoma cells, leading to a poor prognosis

BACKGROUND

ARPC1B has been identified as a key regulator of malignant biological behavior in various tumors. However, its specific role in clear cell renal cell carcinoma (ccRCC) remains poorly understood. This study aims to evaluate the influence of ARPC1B on the prognosis and disease progression in ccRCC patients.

METHODS

Multi-omics data and clinical information from public databases were analyzed to determine the associations between ARPC1B and prognosis, clinical features, immune microenvironment, and drug sensitivity in ccRCC. Co-expression and gene set enrichment analyses were conducted to elucidate the potential role of ARPC1B in ccRCC pathogenesis. Functional assays, including RT-qPCR, CCK8 assays, colony formation assays, immunofluorescence, immunohistochemistry, and xenograft tumor formation in nude mice, were performed to assess ARPC1B's impact on cell proliferation and apoptosis. Flow cytometry and Western blotting were further employed to investigate the underlying molecular mechanisms of ARPC1B in ccRCC.

RESULTS

ARPC1B expression was significantly elevated in ccRCC and associated with an unfavorable prognosis. Both independent and meta-analyses confirmed that ARPC1B is an independent prognostic risk factor in ccRCC. Furthermore, ARPC1B expression significantly correlated with the immune microenvironment and drug sensitivity. In vitro, experiments demonstrated that ARPC1B knockdown suppressed ccRCC cell proliferation and induced apoptosis through the BAX-Bcl-2/c-caspase3/c-PARP axis, which was further validated by in vivo studies.

CONCLUSION

ARPC1B overexpression is associated with poor prognosis, altered immune status, and drug sensitivity in ccRCC. Furthermore, ARPC1B promotes the malignant behavior of ccRCC cells and holds potential as a prognostic biomarker and therapeutic target for ccRCC.

Values of LncRNA SNHG14 in the Differential Diagnosis and Prognosis Evaluation of Acute Ischemic Stroke

The long non-coding RNA (LncRNA) SNHG14 has been investigated for its potential in acute ischemic stroke (AIS) and transient ischemic attack (TIA) diagnosis. Thirty-two healthy people, 85 patients with AIS, and 40 patients with TIA had their blood tested to determine SNHG14 mRNA transcript levels using quantitative real-time polymerase chain reaction (qRT-PCR). A stroke's severity was measured using the Stroke Severity Scale developed by the National Institutes of Health (NIHSS). After 30 days, individuals with AIS were evaluated for progress using a modified Rankin Scale (mRS). There was no significant difference in SNHG14 LncRNA levels between TIA patients and controls, despite the huge rise in AIS incidence (p > 0.05) (all p < 0.001). Compared to those who did well on the AIS test, those who performed poorly had substantially greater levels of SNHG14 LncRNA (mRS 0-1 points) (mRS 0-2). LncRNA SNHG14 had an AUC of 0.714 (80%, 61.18%) when used to identify AIS in TIA patients, and a comparable finding was seen when predicting a poor 30-day prognosis of AIS (73%, 66.67%). There are also graphical representations of the findings. Improvements in NIHSS and mRS scores were associated with increases in SNHG14 LncRNA mRNA levels in individuals diagnosed with AIS. It is critical that we focus entirely on this decision (all p < 0.05). Analysis of the long non-coding RNA known as SNHG14 in the patient's blood can be used to diagnose AIS, rule out TIA, forecast the intensity of the disease, and evaluate the prognosis. You can accomplish everything on that list simultaneously.

Association of systemic inflammatory response index and stroke: a cross-sectional study of NHANES, 2005-2018

Background

Many inflammatory markers like systemic immune-inflammatory index (SII), neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR) are associated with stroke. However, studies on the relationship between stroke and systemic inflammatory response index (SIRI) are scarce. This study was aimed at evaluating the potential association of SIRI with stroke.

Methods

Our cross-sectional study included adults with sufficient SIRI and stroke data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES). We used multivariable logistic regression, interaction tests, smoothed curve fitting, and subgroup analysis for assessing the independent relationship between SIRI and stroke.

Results

Of 36,176 participants in this study, 1,414 (3.9%) had experienced a stroke. In a fully adjusted model, the systemic inflammatory response index displayed a significant and positive correlation with stroke (odds ratio [OR] = 1.09, 95% confidence interval [CI] = 1.04-1.15, p = 0.0006). Meanwhile, the odds of stroke increased by 39% in the 4th quartile, relative to the 1st quartile (OR = 1.39, 95% CI = 1.17-1.65, p = 0.0002). Additional interaction tests and subgroup analysis revealed that age, sex, race, education, marriage, BMI (body mass index), smoking, diabetes mellitus, hypertension, and coronary heart disease (CHD) were not positively correlated (p interaction >0.05). Moreover, we also found a nonlinear correlation between SIRI and stroke, with an inflection point of 2.17.

Conclusion

Our results indicate that SIRI is significantly and positively related to stroke; however, its role in stroke needs to be further confirmed by large-scale prospective studies.

Potential mechanisms for chorioamniotic membrane rupture after subchorionic hematoma

BACKGROUND

Subchorionic hematoma is a risk factor for preterm prelabor rupture of membranes and preterm birth. A small proportion of persistent subchorionic hematoma leads to a chronic abruption-oligohydramnios sequence.

OBJECTIVE

To determine the mechanism by which subchorionic hematomas may damage chorioamniotic membranes.

STUDY DESIGN

1) The number and subtype of macrophages were determined by immunohistochemistry in chorioamniotic membranes from 8 subchorionic hematoma patients who delivered preterm (25.5 (24-32) weeks of gestation (median and range)) and 6 gestational age-matched control patients (25.5 (25-28) weeks of gestation (median and range)). Further, the thickness and fibrosis of the membranes were quantified. 2) We also developed an intrauterine hematoma model in pregnant mice, and the effects of hematoma on the amnion were analyzed by histology and immunofluorescence. 3) In vitro, primary human amnion mesenchymal cells were cocultured with M2-differentiated macrophages, and changes in mesenchymal cells were analyzed.

RESULTS

1) Subchorionic hematoma increased the number of iron-laden macrophages in the human amnion. These macrophages were CD206+, a marker of macrophages required for the maintenance of homeostasis, tissue remodeling, and metabolic adaptations. The collagen layer of the amnion tended to be thickened in patients with subchorionic hematoma. Interestingly, α-smooth muscle actin+ myofibroblasts were increased in the amnion mesenchymal layer in patients with subchorionic hematoma. Vimentin, a mesenchymal marker, was expressed in the epithelial layer of the hematoma amnion. Together, these findings indicate epithelial-mesenchymal transition in the amnion of membranes from pregnancies with subchorionic hematomas. 2) These findings in human amnion were confirmed in a mouse model of intrauterine hematoma. 3) Further, in vitro, coculture of human amnion mesenchymal cells with M2-differentiated human macrophages resulted in transformation of these cells into α-smooth muscle actin-expressing myofibroblasts via the TGF-β‒Smad3 pathway.

CONCLUSION

Subchorionic hematoma induces migration of macrophages to chorioamniotic membranes which activate the transition of amnion mesenchymal cells to myofibroblasts. These myofibroblasts may contribute to fibrosis of the amnion and damage chorioamniotic membranes.

Exosomes from polarized Microglia: Proteomic insights into potential mechanisms affecting intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating form of stroke associated with significant morbidity and mortality. Microglia are intracranial innate immune cell that play critical roles in Intracerebral hemorrhage through direct or indirect means. Vesicle transport is a fundamental mechanism of intercellular communication. Recent studies have identified microglia in specific polarized states correlate with pathogenesis, material and signal transmission in ICH through derived extracellular vesicles. Diverse polarization states trigger distinct functions, however, the exosome proteomes across these states remain poorly characterized. Here, we hypothesized that microglia exosomal profiles vary with polarization states, impacting their functional repertoire and influencing outcomes in cerebral hemorrhage. In vitro model of cerebral hemorrhage, administration of 20 μg/ml LPS-induced M1 microglia derived exosomes (M1-Exo) with HT22 enhanced hemin-induced neuronal death, while IL-4-induced M2 microglia derived exosomes (M2-Exo) significantly reduced hemin-induced cell apoptosis and inflammation. Then we identified novel state-specific proteomic profiles of microglia-derived exosomes under these polarization conditions through label-free quantitative mass spectrometry (LFQ-MS). Analysis of protein content identified several exosomal signature proteins and hundreds of differentially expressed proteins across polarization states. Specifically, proteins including UMOD, NLRP3, ACOD1, IL1RN, heme oxygenase 1 (HMOX1), CCL4, and TNFRSF1B in M1-Exo were enriched in inflammatory pathways, while those in M2-Exo exhibited enrichment in autophagy, ubiquitination, and mitochondrial respiration. The analysis of those diverse exosomal proteins suggested unique proteomic profiles and possible intracellular signal transmission and regulation mechanisms. Together, these findings offer new insights and resources for studying microglia-derived exosome and pave the way for the development of novel therapeutic strategies targeting microglial exosome-mediated pathways.

Benzydamine attenuates microglia-mediated neuroinflammation and ischemic brain injury by targeting cathepsin s

Microglia, the primary immune cells of the central nervous system, play a crucial role in the neuroinflammatory processes following ischemic stroke. Targeting neuroinflammation is a promising strategy to enhance the outcomes of ischemic stroke. Benzydamine (BA), a well-known non-steroidal anti-inflammatory drug, has demonstrated potential in inhibiting pro-inflammatory cytokines across various disease models. However, the potential role of BA in microglial activation and post-stroke neuroinflammation remains unclear. Our study reveals that BA effectively suppresses the lipopolysaccharide (LPS)-stimulated pro-inflammatory responses of primary microglia, with high-dose BA (10 μM) suppressing LPS-induced inflammatory markers by up to 59.1 % in the mRNA levels of IL-1β. Furthermore, BA mitigated ischemic brain injury in experimental stroke mice. BA treatment also significantly attenuated neuroinflammatory responses and attenuates ischemic brain injury in experimental stroke mice. Further investigation revealed that BA reduces the release of the LPS-stimulated pro-inflammatory factors and activation of primary microglia by directly binding to and inhibiting the activity of cathepsin S (CTSS). In conclusion, our study identifies BA as a promising CTSS inhibitor with potential to suppress neuroinflammation following ischemic stroke. Our findings provide a theoretical basis for developing new neuroprotective strategies.

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.

Cell inspired delivery system equipped with natural membrane structures in applications for rescuing ischemic stroke

Ischemic stroke (IS), accounting for 87 % of stroke incidences, constitutes a paramount health challenge owing to neurological impairments and irreversible tissue damage arising from cerebral ischemia. Chief among therapeutic obstacles are the restrictive penetration of the blood-brain barrier (BBB) and insufficient targeting precision, hindering the accumulation of drugs in ischemic brain areas. Motivated by the remarkable capabilities of natural membrane-based delivery vehicles in achieving targeted delivery and traversing the BBB, thanks to their biocompatible architecture and bioactive components, numerous membrane-engineered systems such as cells, cell membranes and extracellular vesicles have emerged as promising platforms to augment IS treatment efficacy with the help of nanotechnology. This review consolidates the primary pathological manifestations following IS, elucidates the unique functionalities of natural membrane drug delivery systems (DDSs) with nanotechnology, as well as delineates the structural characteristics of various natural membranes alongside rational design strategies employed. The review illuminates both the potential and challenges encountered when employing natural membrane DDSs in IS drug therapy, offering fresh perspectives and insights for devising efficacious and practical delivery systems tailored to IS intervention.

Unlocking the potential for optic nerve regeneration over long distances: a multi-therapeutic intervention

Retinal ganglion cells (RGCs) generally fail to regenerate axons, resulting in irreversible vision loss after optic nerve injury. While many studies have shown that modulating specific genes can enhance RGCs survival and promote optic nerve regeneration, inducing long-distance axon regeneration in vivo through single-gene manipulation remains challenging. Nevertheless, combined multi-gene therapies have proven effective in significantly enhancing axonal regeneration. At present, research on promoting optic nerve regeneration remains slow, with most studies unable to achieve axonal growth beyond the optic chiasm or reestablish connections with the brain. Future research priorities include directing axonal growth along correct pathways, facilitating synapse formation and myelination, and modifying the inhibitory microenvironment. These strategies are crucial not only for optic nerve regeneration but also for broader applications in central nervous system repair. In this review, we discuss multifactors therapeutic strategies for optic nerve regeneration, offering insights into advancing nerve regeneration research.

Poststroke Translocator Protein Expression Dynamics and Correlations to Chronic Infarction: A [123I]-CLINDE-SPECT Study

BACKGROUND AND PURPOSE

This study aims to investigate the longitudinal changes in translocator protein (TSPO) following stroke in different brain regions and potential associations with chronic brain infarction.

METHODS

Twelve patients underwent SPECT using the TSPO tracer 6-Chloro-2-(4'-123I-Iodophenyl)-3-(N,N-Diethyl)-Imidazo[1,2-a]Pyridine-3-Acetamide, as well as structural MRI, at 10, 41, and 128 days (median) after ischemic infarction in the middle cerebral artery. TSPO expression was measured in lesional (MRI lesion and SPECT lesion), connected (pons and ipsilesional thalamus), and nonconnected (ipsilesional cerebellum and contralesional occipital cortex) regions. Correlations were explored between the volume of chronic infarction and TSPO expression in nonconnected regions of interest (ROIs) at 128 days RESULTS: Throughout the study period, TSPO levels decreased by 24%-33% in lesional ROIs, while levels increased in connected ROIs by 35%-69% and in nonconnected ROIs by 53%-77%. At 128 days poststroke, TSPO expression in ipsilesional cerebellum positively correlated with chronic infarction volume (p = 0.002, r2 = 0.72).

CONCLUSIONS

This study expands the current knowledge of spatial and temporal TSPO expression in humans by quantifying TSPO changes in lesional, connected, and nonconnected brain regions at three time points after cerebral infarction as well as correlating late-stage TSPO upregulation and chronic infarction volume.

Inflammation-Targeted Biomimetic Nano-Decoys via Inhibiting the Infiltration of Immune Cells and Effectively Delivering Glucocorticoids for Enhanced Multiple Sclerosis Treatment

Excessive infiltration of neutrophil and inflammatory cytokines accumulation as well as the inadequate delivery of drugs to the targeted site are key pathological cascades in multiple sclerosis (MS). Herein, inflammation-targeting biomimetic nano-decoys (TFMN) is developed that inhibit the infiltration of immune cells and effectively deliver glucocorticoids to lesions for enhanced MS treatment. Nano-decoys encapsulated with the glucocorticoid methylprednisolone (MPS) are prepared by coating neutrophil membrane (NM) on nanoparticles formed by the self-assembly of tannic acid and poloxamer188/pluronic68. Benefiting from the natural inflammation-targeting ability of activated neutrophil membranes, TFMN can target the lesion site and prevent neutrophils infiltration by adsorbing and neutralizing elevated neutrophil-related cytokines, subsequently modulating the inflammatory microenvironment in experimental autoimmune encephalomyelitis mice. TFMN exhibits a strong antioxidant capacity and scavenged excessive reactive oxygen species to enhance neuronal protection. Furthermore, at the inflammation site, perforin, discharged by cytotoxic T-lymphocytes, triggered the controlled release of MPS within the TFMN through perforin-formed pores in the NM. Simultaneously, this mechanism protected neurons from perforin-induced toxicity. The MPS liberated at the targeted site achieves optimal drug accumulation, thereby enhancing therapeutic efficacy. In conclusion, the innovative system shows potential for integrating various therapeutic agents, offering a novel strategy for CNS disorders.

Mitochondrial Uncoupling Protein-2 Ameliorates Ischemic Stroke by Inhibiting Ferroptosis-Induced Brain Injury and Neuroinflammation

Ischemic stroke is a devastating disease in which mitochondrial damage or dysfunction substantially contributes to brain injury. Mitochondrial uncoupling protein-2 (UCP2) is a member of the UCP family, which regulates production of mitochondrial superoxide anion. UCP2 is reported to be neuroprotective for ischemic stroke-induced brain injury. However, the molecular mechanisms of UCP2 in ischemic stroke remain incompletely understood. In this study, we investigated whether and how UCP2 modulates neuroinflammation and regulates neuronal ferroptosis following ischemic stroke in vitro and in vivo. Wild-type (WT) and UCP2 knockout (Ucp2-/-) mice were subjected to middle cerebral artery occlusion (MCAO). BV2 cells (mouse microglial cell line) and HT-22 cells (mouse hippocampal neuronal cell line) were transfected with small interfering (si)-RNA or overexpression plasmids to knockdown or overexpress UCP2 levels. Cells were then exposed to oxygen-glucose deprivation and reoxygenation (OGD/RX) to simulate hypoxic injury in vitro. We found that UCP2 expression was markedly reduced in a time-dependent manner in both in vitro and in vivo ischemic stroke models. In addition, UCP2 was mainly expressed in neurons. UCP2 deficiency significantly enlarged infarct volumes, aggravated neurological deficit scores, and exacerbated cerebral edema in mice after MCAO. In vitro knockdown of Ucp2 and in vivo genetic depletion of Ucp2 (Ucp2-/- mice) increased neuronal ferroptosis-related indicators, including Fe2+, malondialdehyde, glutathione, and lipid peroxidation. Overexpression of UCP2 in neuronal cells resulted in reduced ferroptosis. Moreover, knockdown of UCP2 exacerbated neuroinflammation in BV2 microglia and mouse ischemic stroke models, suggesting that endogenous UCP2 inhibits neuroinflammation following ischemic stroke. Upregulation of UCP2 expression in microglia appeared to decrease the release of pro-inflammatory factors and increase the levels of anti-inflammatory factors. Further investigation showed that UCP2 deletion inhibited expression of AMPKα/NRF1 pathway-related proteins, including p-AMPKα, t-AMPKα, NRF1, and TFAM. Thus, UCP2 protects the brain from ischemia-induced ferroptosis by activating AMPKα/NRF1 signaling. Activation of UCP2 represents an attractive strategy for the prevention and treatment of ischemic stroke.

Mechanism of inflammatory response and therapeutic effects of stem cells in ischemic stroke: current evidence and future perspectives

Ischemic stroke is a leading cause of death and disability worldwide, with an increasing trend and tendency for onset at a younger age. China, in particular, bears a high burden of stroke cases. In recent years, the inflammatory response after stroke has become a research hotspot: understanding the role of inflammatory response in tissue damage and repair following ischemic stroke is an important direction for its treatment. This review summarizes several major cells involved in the inflammatory response following ischemic stroke, including microglia, neutrophils, monocytes, lymphocytes, and astrocytes. Additionally, we have also highlighted the recent progress in various treatments for ischemic stroke, particularly in the field of stem cell therapy. Overall, understanding the complex interactions between inflammation and ischemic stroke can provide valuable insights for developing treatment strategies and improving patient outcomes. Stem cell therapy may potentially become an important component of ischemic stroke treatment.

Polygala tenuifolia root extract attenuates ischemic stroke by inhibiting HMGB1 trigger neuroinflammation

Polygala tenuifolia Willd., a famous traditional Chinese medicine, has been widely applied to treat central nervous system diseases. In this study, P. tenuifolia root extract exhibited a moderate anti-ischemic effect on in-vitro oxygen-glucose deprivation/reperfusion (OGD/R) model. In transient middle cerebral artery occlusion (tMCAO) rats, P. tenuifolia root extract significantly attenuated brain infarction and neurological deficits in a dose-dependent manner. Compared with the sham group, the release of damage-associated molecular patterns (DAMPs)-HMGB1 in the ischemic brain was significantly higher, which was inhibited by P. tenuifolia root extract. To further explore such neuroprotective effects whether associated with aseptic inflammation, HMGB1-activated BV2 microglial cells model was established. The extract of P. tenuifolia was found to inhibit the downstream inflammatory response driven by HMGB1, with an IC50 value of 49.46 μg/mL. In addition, the extract was also found to be able to directly interact with HMGB1 in the surface plasmon resonance (SPR) experiment. Phytochemical studies showed that the extract of P. tenuifolia root contains a large number of terpenoids, oligosaccharides and phenolic compounds, which likely contribute to the above observed biological activities. Our results not only provide some data support for the clinical application of P. tenuifolia against cerebral ischemia, but also clarify the potential target of P tenuifolia's anti-inflammatory properties.

Preclinical evaluation on human platelet lysate for the treatment of secondary injury following intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a condition with high mortality and disability. Secondary injury processes following ICH include neuroinflammation, oxidative stress, and neuronal apoptosis. Human platelet lysate (HPL), derived from crushed platelets, is rich in cytokines and has demonstrated therapeutic potential in neurological disorders in several studies. However, studies on HPL for ICH remain limited. In this study, we prepared HPL for intranasal administration in ICH treatment. We determined the concentration of growth factors in HPL, validated the targeting of HPL, and established a mouse model of ICH. We observed that HPL improved neuromotor deficits in ICH mice. Barnes maze training showed that HPL enhanced spatial memory and learning ability in mice. Furthermore, HPL reduced neuroinflammation, brain edema, oxidative stress, neuronal apoptosis, and neural axonal damage. Additionally, 5 % HPL demonstrated potent functional activity with no cytotoxicity in SH-5YSY cell cultures. These findings indicate that HPL is a promising therapeutic approach for mitigating secondary brain injury following ICH.

Immune Cells and Intracerebral Hemorrhage: A Causal Investigation Through Mendelian Randomization

BACKGROUND

The involvement of immune cells in the pathophysiology of intracerebral hemorrhage (ICH) is becoming increasingly recognized, yet their specific causal contributions remain uncertain. The objective of this research is to uncover the potential causal interactions between diverse immune cells and ICH using Mendelian randomization (MR) analysis.

METHODS

Genetic variants associated with 731 immune cell traits were sourced from a comprehensive genome-wide association study (GWAS) involving 3757 participants. Summary statistics data for ICH were acquired from FinnGen, comprising 4056 ICH cases and 371,717 controls. The principal analytical tool utilized in our study was the inverse-variance weighted (IVW) method, incorporated as a key component of a two-sample MR approach. To mitigate potential biases and verify the stability of the conclusions drawn from the primary analytical methods, a series of sensitivity analyses were performed.

RESULTS

MR analysis elucidated 33 immune cell traits with causal associations, comprising B cells (eight traits), conventional dendritic cells (cDC, two traits), maturation stages of T cells (two traits), monocytes (two traits), myeloid cells (five traits), TBNK cells (six traits), and regulatory T cells (Treg, eight traits). DP (CD4+CD8+) %T cell (OR = 0.83, CI = 0.72-0.96, p = 0.013) exhibited the strongest protective effect. In contrast, transitional AC (OR = 1.09, CI = 1.02-1.16, p = 0.006) and IgD- CD27- %lymphocyte (OR = 1.08, CI = 1.00-1.17, p = 0.045) showed a higher tendency to increase the ICH risk. The sensitivity analyses validated the robustness and consistency of these results.

CONCLUSION

Our research provides robust evidence substantiating the causal relationship between specific immunophenotypes and ICH risk. The identification of these findings significantly enhances our understanding of the pathogenic mechanisms underlying ICH, particularly pertaining to the immune system. This breakthrough paves the way for innovative clinical and pharmaceutical research opportunities, potentially promoting the development of targeted therapies and enhanced strategies for managing and preventing ICH.

Neuroglia in stroke

Stroke, ischemic or hemorrhagic, triggers a complex and coordinated glial response, which, to a large extent, defines the progression and outcome of this focal damage of the nervous tissue. Massive cell death in the infarction core results in a release of damage-associated molecular patterns, which, together with blood-borne factors entering the brain through either ruptured vessels or through compromised blood-brain barrier, trigger reactive gliosis. Microglia are the first to migrate toward the lesion, proliferate, and phagocytose cellular debris in and around the infarct core. Reactive astrogliosis occurs around the margins of the infarct core and is characterized by astrocytic proliferation, morphologic remodeling with loss of territorial domain segregation, and transcriptional reprogramming into wound repair astrocytes that form a periinfarct border that protects the healthy tissue and assists postlesional regeneration.

CircFndc3b Mediates Exercise-Induced Neuroprotection by Mitigating Microglial/Macrophage Pyroptosis via the ENO1/KLF2 Axis in Stroke Mice

Circular RNA (circRNA) plays a pivotal role in regulating neurological damage post-ischemic stroke. Previous researches demonstrated that exercise mitigates neurological dysfunction after ischemic stroke, yet the specific contributions of circRNAs to exercise-induced neuroprotection remain unclear. This study reveals that mmu_circ_0001113 (circFndc3b) is markedly downregulated in the penumbral cortex of a mouse model subjected to middle cerebral artery occlusion (MCAO). However, exercise increased circFndc3b expression in microglia/macrophages, alleviating pyroptosis, reducing infarct volume, and enhancing neurological recovery in MCAO mice. Mechanistically, circFndc3b interacted with Enolase 1 (ENO1), facilitating ENO1's binding to the 3' Untranslated Region (3'UTR) of Krüppel-like Factor 2 (Klf2) mRNA, thereby stabilizing Klf2 mRNA and increasing its protein expression, which suppressed NOD-like Receptor Family Pyrin Domain Containing 3 (NLRP3) inflammasome-mediated microglial/macrophage pyroptosis. Additionally, circFndc3b enhanced ENO1's interaction with the 3'UTR of Fused in Sarcoma (FUS) mRNA, leading to increased FUS protein levels and promoting circFndc3b cyclization. These results suggest that circFndc3b mediates exercise-induced anti-pyroptotic effects via the ENO1/Klf2 axis, and a circFndc3b/ENO1/FUS positive feedback loop may potentiate exercise's neuroprotective effects. This study unveils a novel mechanism underlying exercise-induced neuroprotection in ischemic stroke and positions circFndc3b as a promising therapeutic target for stroke management, mimicking the beneficial effects of exercise.

Ischemic Stroke Induces ROS Accumulation, Maladaptive Mitophagy, and Neuronal Apoptosis in Minipigs

Reactive oxygen species (ROS)-induced adaptive/maladaptive mitophagy plays an essential role in the pathophysiology of acute ischemic stroke (AIS). However, most studies have been conducted using rodent models, which limits their clinical application. In this study, we aimed to develop porcine models of permanent stroke and observe the pathophysiological alterations caused by acute ischemic stroke, focusing on ROS-induced mitophagy. Miniature pigs were subjected to lateral frontotemporal electrocoagulation, which resulted in permanent middle cerebral artery occlusion. We investigated global brain damage and mechanisms of adaptive/maladaptive mitophagy caused by ROS and global brain inflammation after AIS. An early neuroinflammatory response was observed in the ipsilateral hemisphere. ROS levels were significantly elevated in the ipsilateral hemisphere and slightly elevated in the contralateral hemisphere. ROS accumulation may be attributed to the increased production and impaired elimination of ROS. In addition, mitophagy and apoptosis were detected in the ischemic core, which may be attributed to ROS accumulation. We propose "distinct-area targeting" interventions aimed at maladaptive mitophagy within the ischemic core of the infarct hemisphere, which may provide new therapeutic targets for the treatment of AIS.

The role of cGAS-STING signaling pathway in ferroptosis

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway has been identified as a crucial mechanism in antiviral defense and innate immunity pathway. Ferroptosis, characterized by iron dependence and lipid peroxidation, represents a specialized form of cell death. A burgeoning collection of studies has demonstrated that the cGAS-STING signaling pathway participates in the homeostatic regulation of the organism by modulating ferroptosis-associated enzyme activity or gene expression. Consequently, elucidating the specific roles of the STING signaling pathway and ferroptosis in vivo is vital for targeted disease intervention. This review systematically examines the interactions between the cGAS-STING signaling pathway and ferroptosis, highlighting their influence on disease progression in the contexts of inflammation, injury, and cancerous cell dynamics. Understanding these interactions may provide novel therapeutic strategies. The STING pathway has been implicated in the regulation of various cell death mechanisms, including apoptosis, pyroptosis, necroptosis, autophagy, and ferroptosis. Our focus primarily addresses the role and mechanism of the cGAS-STING signaling pathway and ferroptosis in diseases, limiting discussion of other cell death modalities and precluding a comprehensive overview of the pathway's additional functions.

Profiling immune cell-related gene features and immunoregulatory ceRNA in ischemic stroke

Molecules in immune cells plays a vital role in the pathogenesis of ischemic stroke (IS). The aim of this study is to profile the landscape of molecules on the basis of immune cells in IS peripheral blood and construct an immunoregulatory competing endogenous RNA (ceRNA) network. We collected and combined multiple public transcriptome datasets from the peripheral blood of IS patients and healthy controls. CIBERSORT deconvolution revealed that the proportions of CD8 and CD4 naive T cells, monocytes, and neutrophils changed significantly in the IS group. Intersecting the immune cell-related genes identified by weighted gene co-expression network analysis (WGCNA) and differential expression analysis, 38 overlapping candidate biomarkers were selected. Three machine learning algorithms, including least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), and random forest were applied, and 11 distinct immune cell-related genes were identified. We obtained the mRNA-miRNA and miRNA-lncRNA interactions from StarBase v3.0, and constructed a ceRNA network based on the differentially expressed mRNAs, miRNAs, and lncRNAs. The aberrant expression of HECW2-centered ceRNAs in the peripheral blood of in-house patients was validated using quantitative PCR. We also revealed that the expression of HECW2 was positively correlated with lncRNAs LINC02593 through miRNAs miR-130a-3p, miR-130b-3p and miR-148b-3p in cells. These results show that there are distinct immune features between IS patients and healthy controls. The ceRNA network may help elucidate the mechanism of immune cell-related genes in IS and may serve as a therapeutic target.

A20 negatively regulates necroptosis-induced microglia/macrophages polarization and mediates cerebral ischemic tolerance via inhibiting the ubiquitination of RIP3

Neuronal necroptosis appears to be suppressed by the deubiquitinating enzyme A20 and is capable to regulate the polarization of microglia/macrophages after cerebral ischemia. We have demonstrated that hypoxic preconditioning (HPC) can alleviate receptor interacting protein 3 (RIP3)-induced necroptosis in CA1 after transient global cerebral ischemia (tGCI). However, it is still unclear whether HPC serves to regulate the phenotypic polarization of microglia/macrophages after cerebral ischemia by mitigating neuronal necroptosis. We hence aim to elucidate the underlying mechanism(s) by which the ubiquitination of RIP3-dependent necroptosis regulated by A20 affects microglia/macrophages phenotype after cerebral ischemic tolerance. We found that microglia/macrophages in CA1 of rats underwent M1 and M2 phenotypic polarization in response to tGCI. Notably, the treatment with HPC, as well as inhibitors of necroptosis, including Nec-1 and mixed lineage kinase domain-like (MLKL) siRNA, attenuated neuroinflammation associated with M1 polarization of microglia/macrophages induced by tGCI. Mechanistically, HPC was revealed to upregulate A20 and in turn enhance the interaction between A20 and RIP3, thereby reducing K63-linked polyubiquitination of RIP3 in CA1 after tGCI. Consequently, RIP3-dependent necroptosis and the M1 polarization of microglia/macrophages were blocked either by HPC or via overexpression of A20 in neurons, which ultimately mitigated cerebral injury in CA1 after tGCI. These data support that A20 serves as a crucial mediator of microglia/macrophages polarization by suppressing neuronal necroptosis in a RIP3 ubiquitination-dependent manner after tGCI. Also, a novel mechanism by which HPC functions in cerebral ischemic tolerance is elucidated.

Tet2-mediated clonal hematopoiesis modestly improves neurological deficits and is associated with inflammation resolution in the subacute phase of experimental stroke

Introduction

Recent work has revealed that clonal hematopoiesis (CH) is associated with a higher risk of numerous age-related diseases, including ischemic stroke, however little is known about whether it influences stroke outcome independent of its widespread effects on cardiovascular disease. Studies suggest that leukocytes carrying CH driver mutations have an enhanced inflammatory profile, which could conceivably exacerbate brain injury after a stroke.

Methods

Using a competitive bone marrow transplant model of Tet2-mediated CH, we tested the hypothesis that CH would lead to a poorer outcome after ischemic stroke by augmenting brain inflammation. Stroke was induced in mice by middle cerebral artery occlusion and neurological outcome was assessed at acute (24 h) and subacute (14 d) timepoints. Brains were collected at both time points for histological, immunofluorescence and gene expression assays.

Results

Unexpectedly, Tet2-mediated CH had no effect on acute stroke outcome but led to a reduction in neurological deficits during the subacute phase. This improved neurological outcome was associated with lower levels of brain inflammation as evidenced by lower transcript levels of various inflammatory molecules alongside reduced astrogliosis.

Discussion

These findings suggest that Tet2-mediated CH may have beneficial effects on outcome after stroke, contrasting with the conventional understanding of CH whereby leukocytes with driver mutations promote disease by exacerbating inflammation.

Association of the Systemic Inflammation Response Index with Functional Outcome in Acute Large Vessel Occlusion Stroke Patients Receiving Mechanical Thrombectomy

Purpose

The systemic inflammation response index (SIRI) has recently emerged as a novel inflammatory and prognostic marker across various diseases. However, there is limited research examining the relationship between SIRI and 90-day functional outcome in patients with acute large vessel occlusion stroke (ALVOS) undergoing mechanical thrombectomy (MT). This study aimed to investigate the potential of SIRI as an innovative, inflammation-based predictor of 90-day functional outcome.

Methods

This retrospective cohort study consecutively recruited 604 Chinese patients with diagnosed ALVOS who underwent MT at the First College of Clinical Medical Science of China Three Gorges University between July 2017 and April 2023. Comprehensive data, including baseline demographic and clinical characteristics, were systematically extracted from electronic medical records. Poor functional outcome at 90 days was defined as modified Rankin Scale (mRS) score ≥3. We employed logistic regression models, curve fitting, sensitivity analyses, subgroup analyses, and receiver operating characteristic (ROC) curves to validate the association between SIRI and poor outcome, as well as to assess the predictive efficacy.

Results

Final analysis included 604 ALVOS subjects of whom 54.3% experienced poor functional outcome at 90 days. In the multivariate analysis, after adjusting for potential confounders, SIRI remained significantly associated with an elevated risk of poor outcomes (OR 1.18, 95% CI 1.08-1.28, P < 0.001). Nonlinear curve fitting revealed a reverse J-shaped association between SIRI and poor outcomes, with inflection points at 4.5. Subgroup analyses showed no significant interactions (all P for interaction > 0.05), However, atrial fibrillation demonstrated a significant interaction (all P for interaction = 0.001).

Conclusion

SIRI shows promise as a novel prognostic marker for 90-day functional outcome in patients with ALVOS undergoing MT. The identified nonlinear relationship and inflection point may provide valuable insights for risk stratification and clinical decision-making in this specific patient population.

Optimal different adeno-associated virus capsid/promoter combinations to target specific cell types in the common marmoset cerebral cortex

To achieve cell-type-specific gene expression, using target cell-type-tropic different adeno-associated virus (AAV) capsids is advantageous. However, their tropism across brain cell types in nonhuman primates has not been fully elucidated. We assessed the tropism of nine AAV serotype capsids (AAV1, 2, 5, 6, 7, 8, 9, rh10, and DJ) expressing EGFP by chicken β-actin hybrid (CBh) promoter in marmoset cerebral cortical cells. All nine AAV capsid vectors, especially AAV9 and AAVrh10, caused highly neuron-selective EGFP expression. Some AAV capsids, including AAV5, induced EGFP expression to a lesser extent in oligodendrocytes. Different ubiquitous cytomegalovirus (CMV) and CMV early enhancer/chicken β-actin (CAG) promoters exhibited similar neuron-predominant transgene expression. Conversely, all nine AAV capsid vectors with the astrocyte-specific hGFA(ABC1D) promoter selectively expressed EGFP in astrocytes, except AAV5, which modestly expressed EGFP in oligodendrocytes. Oligodendrocyte-specific mouse myelin basic protein (mMBP) promoter in AAV5 vectors expressed EGFP in oligodendrocytes specifically and efficiently. The following are optimal combinations of capsids and promoters for cell-type-specific expression: AAV9 or AAVrh10 and ubiquitous CBh or CMV promoter for neuron-specific transgene expression, AAV2 or AAV7 and hGFA(ABC1D) promoters for astrocyte-specific transgene expression, and AAV5 and mMBP promoters for oligodendrocyte-specific transgene expression.

Brain white matter damage biomarkers

White matter (WM), constituting nearly half of the human brain's mass, is pivotal for the rapid transmission of neural signals across different brain regions, significantly influencing cognitive processes like learning, memory, and problem-solving. The integrity of WM is essential for brain function, and its damage, which can occur due to conditions such as multiple sclerosis (MS), stroke, and traumatic brain injury, results in severe neurological deficits and cognitive decline. The primary objective of this book chapter is to discuss the clinical significance of fluid biomarkers in assessing WM damage within the central nervous system (CNS). It explores the biological underpinnings and pathological changes in WM due to various neurological conditions and details how alterations can be detected and quantified through fluid biomarkers. By examining biomarkers like Myelin Basic Protein (MBP), Neurofilament light chain (NFL), and others, the chapter highlights their role in enhancing diagnostic precision, monitoring disease progression, and guiding therapeutic interventions, thus providing crucial insights into maintaining WM integrity and preventing cognitive and physical disabilities.

Intranasal Delivery of Curcumin Nanoparticles Improves Neuroinflammation and Neurological Deficits in Mice with Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) represents one of the most severe subtypes of stroke. Due to the complexity of the brain injury mechanisms following ICH, there are currently no effective treatments to significantly improve patient functional outcomes. Curcumin, as a potential therapeutic agent for ICH, is limited by its poor water solubility and oral bioavailability. In this study, mPEG-PCL is used to encapsulate curcumin, forming curcumin nanoparticles, and utilized the intranasal administration route to directly deliver curcumin nanoparticles from the nasal cavity to the brain. By inhibiting pro-inflammatory neuroinflammation of microglia following ICH in mice, reprogramming pro-inflammatory microglia toward an anti-inflammatory function, and consequently reducing neuronal inflammatory death and hematoma volume, this approach improved blood-brain barrier damage in ICH mice and promoted the recovery of neurological function post-stroke. This study offers a promising therapeutic strategy for ICH to mediate neuroinflammatory microenvironments.

PRDX1 Interfering Peptide Disrupts Amino Acids 70-90 of PRDX1 to Inhibit the TLR4/NF-κB Signaling Pathway and Attenuate Neuroinflammation and Ischemic Brain Injury

Ischemic stroke ranks among the leading causes of death and disability in humans and is accompanied by motor and cognitive impairment. However, the precise mechanisms underlying injury after stroke and effective treatment strategies require further investigation. Peroxiredoxin-1 (PRDX1) triggers an extensive inflammatory cascade that plays a pivotal role in the pathology of ischemic stroke, resulting in severe brain damage from activated microglia. In the present study, we used molecular dynamics simulation and nuclear magnetic resonance to detect the interaction between PRDX1 and a specific interfering peptide. We used behavioral, morphological, and molecular experimental methods to demonstrate the effect of PRDX1-peptide on cerebral ischemia-reperfusion (I/R) in mice and to investigate the related mechanism. We found that PRDX1-peptide bound specifically to PRDX1 and improved motor and cognitive functions in I/R mice. In addition, pretreatment with PRDX1-peptide reduced the infarct area and decreased the number of apoptotic cells in the penumbra. Furthermore, PRDX1-peptide inhibited microglial activation and downregulated proinflammatory cytokines including IL-1β, IL-6, and TNF-α through inhibition of the TLR4/NF-κB signaling pathway, thereby attenuating ischemic brain injury. Our findings clarify the precise mechanism underlying PRDX1-induced inflammation after ischemic stroke and suggest that the PRDX1-peptide can significantly alleviate the postischemic inflammatory response by interfering with PRDX1 amino acids 70-90 and thereby inhibiting the TLR4/NF-κB signaling pathway. Our study provides a theoretical basis for a new therapeutic strategy to treat ischemic stroke.

Acute astrocytic reaction is associated with 3-month functional outcome after stroke treated with endovascular therapy

INTRODUCTION

More than 50% of large vessel occlusion (LVO) acute ischemic stroke (AIS) patients treated with endovascular therapy (EVT) remain severely disabled at 3 months. We hypothesized that acute astrocytic inflammatory response may play a pivotal role in post-AIS brain changes associated with poor functional outcome. We proposed to evaluate the level of YKL-40, a glycoprotein mainly released by reactive astrocytes.

PATIENTS AND METHODS

A monocentric prospective cohort study was conducted on consecutive LVO AIS patients treated with EVT. Three blood samples (before, within 1 and 24-hour post-EVT) were collected to measure plasma YKL-40 concentrations. Functional outcome was assessed according to the modified Rankin Scale (mRS) score at 3 months.

RESULTS

Between 2016 and 2020, 120 patients were included. The plasma concentration of YKL-40 before EVT was statistically and independently associated with 3-month worse functional outcome (adjusted cOR, 1.59; 95% CI [1.05-2.44], p = 0.027) but not the two following samples 1-hour and 24-hour post-EVT. Accordingly, we found that excellent functional outcome was associated with a lower level of YKL-40 before and within 1 h after EVT (p = 0.005 and p = 0.003, respectively) but not when measured 24 h after EVT (p = 0.2).

DISCUSSION AND CONCLUSION

This study suggests that the astrocytic reaction to acute brain hypoxia, especially before recanalization, is associated with worse functional outcome. Such early biomarker of the astrocytic response in AIS may optimize individualized care in the future.

CLINICAL TRIAL REGISTRATION-URL

http://www.clinicaltrials.gov. Unique identifier: NCT02900833.

Celastrol alleviates secondary brain injury following intracerebral haemorrhage by inhibiting neuronal ferroptosis and blocking blood-brain barrier disruption

Background

Following recent research advancements, an increasing level of evidence had been published to indicate that celastrol exerted a therapeutic effect on a range of nervous system diseases. This study therefore aimed to investigate the potential involvement of celastrol on ferroptosis and the blood-brain barrier disruption in intracerebral haemorrhage.

Methods

We established a rat intracerebral haemorrhage and adrenal pheochromocytoma cell (PC12) OxyHb models using an ACSL4 overexpression vector. Ferroptosis-related indices were assessed using corresponding assay kits, and immunofluorescence and flow cytometry were used to measure reactive oxygen species (ROS) levels. Additionally, quantitative PCR (qPCR) and western blot analyses were conducted to evaluate the expression of key proteins and elucidate the role of celastrol in intracerebral haemorrhage (ICH).

Results

Celastrol significantly improved neurological function scores, blood-brain barrier integrity, and brain water content in rats with ICH. Moreover, subsequent analysis of ferroptosis-related markers, such as Fe2+, ROS, MDA, and SOD, suggested that celastrol exerted a protective effect against the oxidative damage induced by ferroptosis in ICH rats and cells. Furthermore, Western blotting indicated that celastrol attenuated ferroptosis by modulating the expression levels of key proteins, including acyl-CoA synthetase long-chain family member 4 (ACSL4), glutathione peroxidase 4 (GPX4), ferritin heavy chain 1 (FTH1), and anti-transferrin receptor 1 (TFR1) both in vitro and in vivo. ACSL4 overexpression attenuated the neuroprotective effects of celastrol on ICH in vitro. Molecular docking analysis revealed that celastrol interacted with ACSL4 via the GLU107, GLN109, ASN111, and LYS357 binding sites.

Conclusions

Celastrol exerted antioxidant properties and aids in neurological recovery after stroke by suppressing ACSL4 expression during ferroptosis. As such, this drug represented a promising pharmaceutical candidate for the treatment of ICH.

Electroacupuncture suppresses NK cell infiltration and activation in the ischemic mouse brain through STAT3 inhibition

AIMS

Electroacupuncture (EA) at Shuigou (GV26) and Baihui (GV20) has shown therapeutic benefits for stroke patients. Given that natural killer (NK) cell infiltration into the brain significantly contributes to the exacerbation of cerebral ischemic injury, this study investigated the impact of EA at Shuigou (GV26) and Baihui (GV20) on post-ischemic brain infiltration and activation of NK cells.

METHODS

Neurological deficit score, rotarod test, adhesive removal test, and TTC staining were used to evaluate the beneficial effects of EA in middle cerebral artery occlusion (MCAO) mice. The inhibitory effect of EA on STAT3 activation was assessed using Western blot. Flow cytometry was used to explore the impact of EA on post-ischemic brain infiltration of NK cells, as well as the activating receptor NKG2D expression and interferon-γ (IFN-γ) production by these infiltrated NK cells.

RESULTS

EA significantly alleviated neurological functional deficits and reduced brain infarction in MCAO mice. Abundant NK cells infiltrated into the ischemic hemisphere, but this infiltration was significantly suppressed by EA. Furthermore, EA attenuated NKG2D levels and reduced production of IFN-γ by NK cells in the ischemic brain. Notably, EA's inhibitory effect on post-ischemic NK cell brain infiltration and activation was comparable to that of STAT3 inhibition. The combination of EA and STAT3 inhibition did not result in further enhancement of the inhibitory effect. Moreover, the protective effects of EA against MCAO injury were abolished when STAT3 was activated.

CONCLUSION

Our findings suggest that EA at Shuigou (GV26) and Baihui (GV20) inhibits the post-ischemic brain infiltration and activation of NK cells through STAT3 inhibition, significantly contributing to its therapeutic effects against brain ischemia.

The Role of Gut Microbiota in Blood-Brain Barrier Disruption after Stroke

Growing evidence has proved that alterations in the gut microbiota have been linked to neurological disorders including stroke. Structural and functional disruption of the blood-brain barrier (BBB) is observed after stroke. In this context, there is pioneering evidence supporting that gut microbiota may be involved in the pathogenesis of stroke by regulating the BBB function. However, only a few experimental studies have been performed on stroke models to observe the BBB by altering the structure of gut microbiota, which warrant further exploration. Therefore, in order to provide a novel mechanism for stroke and highlight new insights into BBB modification as a stroke intervention, this review summarizes existing evidence of the relationship between gut microbiota and BBB integrity and discusses the mechanisms of gut microbiota on BBB dysfunction and its role in stroke.

Acute nicotine exposure attenuates neurological deficits, ischemic injury and brain inflammatory responses and restores hippocampal long-term potentiation in ischemic stroke followed by lipopolysaccharide-induced sepsis-like state

Ischemic stroke is followed by an increased susceptibility to bacterial infections, which exacerbate histological stroke outcome, neurological deficits and memory impairment due to increased neuroinflammation and neurotransmitter dysfunction. Pharmacological activation of nicotinic acetylcholine receptors was suggested to mitigate brain inflammatory responses in ischemic stroke. The functional responses associated with nicotinic acetylcholine receptor activation were unknown. In this study, male NMRI mice subjected to transient intraluminal middle cerebral artery occlusion (MCAO) were intraperitoneally exposed to vehicle treatment or Escherichia coli lipopolysaccharide (LPS; 4 mg/kg)-induced sepsis-like state 24 h post-MCAO, followed by intraperitoneal administration of vehicle or nicotine (0.5 mg/kg) 30 min later. Over 96 h, rectal temperature, neurological deficits, spontaneous locomotor activity, working memory, ischemic injury, synaptic plasticity, and brain inflammatory responses were evaluated by temperature measurement, behavioral analysis, infarct volumetry, electrophysiological recordings, and polymerase-chain reaction analysis. LPS-induced sepsis induced hypothermia, increased general and focal neurological deficits, reduced spontaneous exploration behavior, reduced working memory, and increased infarct volume post-MCAO. Additional treatment with nicotine attenuated LPS-induced hypothermia, reduced neurological deficits, restored exploration behavior, restored working memory, and reduced infarct volume. Local field potential recordings revealed that LPS-induced sepsis decreased long-term potentiation (LTP) in the dentate gyrus post-MCAO, whereas concomitant nicotine exposure restored LTP in the contralateral dentate gyrus. LPS-induced sepsis increased microglial/ macrophage Iba-1 mRNA and astrocytic GFAP mRNA levels post-MCAO, whereas add-on nicotine treatment reduced astrocytic GFAP mRNA. Taken together, these findings indicate that acute nicotine exposure enhances functional stroke recovery. Future studies will have to evaluate the effects of (1) chronic nicotine exposure, a clinically relevant vascular risk factor, and (2) the cessation of nicotine exposure, which is widely recommended post-stroke, but might have detrimental effects in the early stroke recovery phase.

The intervention mechanism of Tanshinone IIA in alleviating neuronal injury induced by HMGB1 or TNF-α-mediated microglial activation

Tanshinone IIA (Tan IIA), a neuroprotective natural compound extracted from Salvia miltiorrhiza, is used in stroke treatment. However, elucidating Tan IIA's neuroprotective mechanisms remains challenging due to limitations in assessing drug efficacy and biochemical parameters in clinical studies. This study investigated Tan IIA's impact on neuroinflammatory responses and its neuroprotective mechanisms using HMGB1- or TNF-α-stimulated BV2 microglia in a co-culture system with primary neuron cells. The results indicated that Tan IIA significantly reduced microglial activation induced by TNF-α or HMGB1. Concurrently, Tan IIA disrupted the interactions between HMGB1 and toll-like receptor 4 (TLR4), and between TNF-α and TNF receptor 1 (TNFR1), modulating the HMGB1/TLR4/nuclear factor-kappa B (NF-κB) and TNF-α/TNFR1/NF-κB signaling pathways and related protein expressions. Moreover, co-culture experiments showed that neuronal apoptosis induced by microglial activation was reversed by Tan IIA. In conclusion, Tan IIA provides neuroprotection by modulating signaling pathways in microglia, thus preventing neuronal apoptosis. This study offers new insights into therapeutic targets for ischemic stroke.