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The ischemic stroke is a major global health concern, with high mortality and disability rates. Unfortunately, there is a dearth of effective clinical interventions for managing poststroke neuroinflammation and blood-brain barrier (BBB) disruption that are crucial for the brain injury evolving and neurological deficits. By leveraging the pathological progression of an ischemic stroke, we developed an M2 microglia-targeting lipid nanoparticle (termed MLNP) approach that can selectively deliver mRNA encoding phenotype-switching interleukin-10 (m IL-10 ) to the ischemic brain, creating a beneficial feedback loop that drives microglial polarization toward the protective M2 phenotypes and augments the homing of m IL-10 -loaded MLNPs (m IL-10 @MLNPs) to ischemic regions. In a transient middle cerebral artery occlusion (MCAO) mouse model of an ischemic stroke, our findings demonstrate that intravenously injected m IL-10 @MLNPs induce IL-10 production and enhance the M2 polarization of microglia. The resulting positive loop reinforces the resolution of neuroinflammation, restores the impaired BBB, and prevents neuronal apoptosis after stroke. Using a permanent distal MCAO mouse model of an ischemic stroke, the neuroprotective effects of m IL-10 @MLNPs have been further validated by the attenuation of the sensorimotor and cognitive neurological deficits. Furthermore, the developed mRNA-based targeted therapy has great potential to extend the therapeutic time window at least up to 72 h poststroke. This study depicts a simple and versatile LNP platform for selective delivery of mRNA therapeutics to cerebral lesions, showcasing a promising approach for addressing an ischemic stroke and associated brain conditions.

Background: The Catfish stent retriever is a newly developed mechanical thrombectomy device for rapid recanalisation in emergent large vessel occlusion (ELVO) stroke. The current trial aimed to assess whether the Catfish stent retriever is non-inferior to the Solitaire stent retriever in terms of outcomes in ELVO stroke., Methods: This was a randomised, prospective, parallel-group, multicentre, open-label, non-inferiority study conducted at 18 sites in China. The primary outcome was the proportion of cases with successful recanalisation (modified thrombolysis in cerebral infarction score of 2b or 3) following the procedure. Secondary efficacy outcomes included the National Institutes of Health Stroke Scale scores at 24 hours and 7 days or discharge if earlier, time from artery puncture to successful recanalisation and good clinical outcome (modified Rankin scale score ≤2) at 90 days. Safety outcomes included symptomatic intracranial haemorrhage, all cause-death and severe adverse events at 90 days., Results: Between 3 March 2019 and 5 June 2021, 118 and 120 patients were randomly allocated to the Catfish and Solitaire groups, respectively. The primary endpoint after all endovascular procedures was non-inferior in the Catfish group (88.5%, 100/113) than in the Solitaire group (87.7%, 100/114), with a rate difference (RD) of 0.78% (95% CI -7.64 to -9.20; p=0.001). Sensitivity analysis only considering the per-protocol set also yielded similar results, with an RD of 0.83% (95% CI -7.03 to -8.70; p<0.001). Additionally, the proportions of cases with good clinical outcomes (47.8% vs 50.0%, p=0.739) and all-cause death rates (17.7% vs 18.8%, p=0.700) were similar in both groups at 90 days., Conclusions: The Catfish stent retriever is an effective and safe device for endovascular recanalisation in ELVO stroke., Trial Registration Number: NCT03820882., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Microglial polarization is one of the most promising therapeutic targets for multiple central nervous system (CNS) disorders, including ischemic stroke. However, detailed transcriptional alteration of microglia following cerebral ischemic stroke remains largely unclear., Methods: Focal cerebral ischemia was induced by transient middle cerebral artery occlusion (tMCAO) for 60 min in mice. Single-cell RNA sequencing (scRNA-seq) was performed using ischemic brain tissues from tMCAO and sham mice 3 days after surgery. Ch25h -/- mice were used to investigate the role of specific microglia subcluster on post-stroke infarct volume and neuroinflammation., Results: We identified a relatively homeostatic subcluster with enhanced antigen processing and three "ischemic stroke associated microglia" (ISAM): MKI67 + , CH25H + and OASL + subclusters. We found the MKI67 + subcluster undergo proliferation and differentiation into CH25H + and OASL + subclusters. CH25H + microglia was a critical subcluster of ISAM that exhibited increased phagocytosis and neuroprotective property after stroke. Ch25h -/- mice developed significantly increased infarct volume following ischemic stroke compared to Ch25h +/- . Meanwhile, the OASL + subcluster accumulated in the ischemic brain and was associated with the evolving of neuroinflammation after stroke, which was further aggravated in the aged mice brain., Conclusions: Our data reveal previously unrecognized roles of the newly defined CH25H + and OASL + microglia subclusters following ischemic stroke, with novel insights for precise microglia modulation towards stroke therapy., (© 2023. The Author(s).)

Ischemic stroke results in blood-brain barrier (BBB) disruption, during which the reciprocal interaction between ischemic neurons and components of the BBB appears to play a critical role. However, the underlying mechanisms for BBB protection remain largely unknown. In this study, we found that Serpina3n, a serine protease inhibitor, was significantly upregulated in the ischemic brain, predominantly in ischemic neurons from 6 hours to 3 days after stroke. Using neuron-specific adeno-associated virus (AAV), intranasal delivery of recombinant protein, and immune-deficient Rag1 -/- mice, we demonstrated that Serpina3n attenuated BBB disruption and immune cell infiltration following stroke by inhibiting the activity of granzyme B (GZMB) and neutrophil elastase (NE) secreted by T cells and neutrophils. Furthermore, we found that intranasal delivery of rSerpina3n significantly attenuated the neurologic deficits after stroke. In conclusion, Serpina3n is a novel ischemic neuron-derived proteinase inhibitor that counterbalances BBB disruption induced by peripheral T cell and neutrophil infiltration after ischemic stroke. These findings reveal a novel endogenous protective mechanism against BBB damage with Serpina3n being a potential therapeutic target in ischemic stroke.

Stroke, including ischemic stroke and hemorrhagic stroke can cause massive neuronal death and disruption of brain structure, which is followed by secondary inflammatory injury initiated by pro-inflammatory molecules and cellular debris. Phagocytic clearance of cellular debris by microglia, the brain's scavenger cells, is pivotal for neuroinflammation resolution and neurorestoration. However, microglia can also exacerbate neuronal loss by phagocytosing stressed-but-viable neurons in the penumbra, thereby expanding the injury area and hindering neurofunctional recovery. Microglia constantly patrol the central nervous system using their processes to scour the cellular environment and start or cease the phagocytosis progress depending on the "eat me" or "don't eat me'' signals on cellular surface. An optimal immune response requires a delicate balance between different phenotypic states to regulate neuro-inflammation and facilitate reconstruction after stroke. Here, we examine the literature and discuss the molecular mechanisms and cellular pathways regulating microglial phagocytosis, their resulting effects in brain injury and neural regeneration, as well as the potential therapeutic targets that might modulate microglial phagocytic activity to improve neurological function after stroke.

The metabolic reprogramming of peripheral CD4 + T cells that occurs after stroke can lead to imbalanced differentiation of CD4 + T cells, including regulation of T cells, and presents a promising target for poststroke immunotherapy. However, the regulatory mechanism underlying the metabolic reprogramming of peripheral CD4 + T cell remains unknown. In this study, using combined transcription and metabolomics analyses, flow cytometry, and conditional knockout mice, we demonstrate that the receptor for advanced glycation end products (RAGE) can relay the ischemic signal to CD4 + T cells, which underwent acetyl coenzyme A carboxylase 1(ACC1)-dependent metabolic reprogramming after stroke. Furthermore, by administering soluble RAGE (sRAGE) after stroke, we demonstrate that neutralization of RAGE reversed the enhanced fatty acid synthesis of CD4 + T cells and the post-stroke imbalance of Treg/Th17. Finally, we found that post-stroke sRAGE treatment protected against infarct volume and ameliorated functional recovery. In conclusion, sRAGE can serve as a novel immunometabolic modulator that ameliorates ischemic stroke recovery by inhibiting fatty acid synthesis and thus favoring CD4 + T cells polarization toward Treg after cerebral ischemia injury. The above findings provide new insights for the treatment of neuroinflammatory responses after ischemia stroke.

Ischemic stroke is the leading cause of disabilities worldwide. MicroRNA-377 (miR-377) plays important roles in ischemic injury. The present study focused on the mechanisms of miR-377 in protecting ischemic brain injury in rats. Cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in rats. Primary rat microglial cells and brain microvascular endothelial cells (BMECs) were exposed to oxygen-glucose deprivation (OGD). The concentrations of cytokines (TNF-α, IL-1β, IL-6, IFN-γ, TGF-β, MMP2, COX2, and iNOS) in the culture medium were measured by specific ELISA. Tube formation assay was for the in vitro study of angiogenesis. Luciferase reporter assay was performed to confirm whether VEGF and EGR2 were direct targets of miR-377. The MCAO rats were intracerebroventricular (ICV) injection of miR-377 inhibitor to assess its protective effects in vivo. MiR-377 levels were decreased in the rat brain tissues at 1, 3, and 7 d after MCAO. Both microglia cells and BMECs under OGD showed markedly lower expression levels of miR-377 while higher expression levels of EGR2 and VEGF compared to those under normoxia conditions. Knockdown of miR-377 inhibited microglial activation and the release of pro-inflammatory cytokines after OGD. Suppression of miR-377 promoted the capillary-like tube formation and cell proliferation and migration of BMECs. The anti-inflammation effect of EGR2 and the angiogenesis effect of VEGF were regulated by miR-377 after OGD. Inhibition of miR-377 decreased cerebral infarct volume and suppressed cerebral inflammation but promoted angiogenesis in MCAO rats. Knockdown of miR-377 lessened the ischemic brain injury through promoting angiogenesis and suppressing cerebral inflammation. J. Cell. Biochem. 119: 327-337, 2018. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)