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Large artery atherosclerosis (LAA) is a prevalent cause of acute ischemic stroke (AIS). Understanding the mechanisms linking atherosclerosis to stroke is essential for developing appropriate intervention strategies. Here, we found that the exosomal miRNA Novel-3 is selectively upregulated in the plasma of patients with LAA-AIS. Notably, Novel-3 was predominantly expressed in macrophage-derived foam cells, and its expression correlated with atherosclerotic plaque vulnerability in patients undergoing carotid endarterectomy. Exploring the function of Novel-3 in a mouse model of cerebral ischemia, we found that Novel-3 exacerbated ischemic injury and targeted microglia and macrophages expressing ionized calcium-binding adapter molecule 1 in peri-infarct regions. Mechanistically, Novel-3 increased ferroptosis and neuroinflammation by interacting with striatin (STRN) and downregulating the phosphoinositide 3-kinase-AKT-mechanistic target of rapamycin signaling pathway. Blocking Novel-3 activity or overexpressing STRN provided neuroprotection under ischemic conditions. Our findings suggest that exosomal Novel-3, which is primarily derived from macrophage-derived foam cells, targets microglia and macrophages in the brain to induce neuroinflammation and could serve as a potential therapeutic target for patients with stroke who have atherosclerosis., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Background: Stroke is a leading cause of death worldwide, with a lack of effective treatments for improving the prognosis. The aim of the present study was to identify novel therapeutic targets for functional outcome after ischemic stroke ., Methods and Results: Cis-expression quantitative trait loci data for druggable genes were used as instrumental variables. The primary outcome was the modified Rankin Scale score at 3 months after ischemic stroke, evaluated as a dichotomous variable (3-6 versus 0-2) and also as an ordinal variable. Drug target Mendelian randomization, Steiger filtering analysis, and colocalization analysis were performed. Additionally, phenome-wide Mendelian randomization analysis was performed to identify the safety of the drug target genes at the genetic level. Among >2600 druggable genes, genetically predicted expression of 16 genes ( ABCC2 , ATRAID , BLK , CD93 , CHST13 , NR1H3 , NRBP1 , PI3 , RIPK4 , SEMG1 , SLC22A4 , SLC22A5 , SLCO3A1 , TEK , TLR4 , and WNT10B ) demonstrated the causal associations with ordinal modified Rankin Scale ( P <1.892×10 -5 ) or poor functional outcome (modified Rankin Scale 3-6 versus 0-2, P <1.893×10 -5 ). Steiger filtering analysis suggested potential directional stability ( P <0.05). Colocalization analysis provided further support for the associations between genetically predicted expression of ABCC2 , NRBP1 , PI3 , and SEMG1 with functional outcome after ischemic stroke. Furthermore, phenome-wide Mendelian randomization revealed additional beneficial indications and few potential safety concerns of therapeutics targeting ABCC2 , NRBP1 , PI3 , and SEMG1 , but the robustness of these results was limited by low power., Conclusions: The present study revealed 4 candidate therapeutic targets for improving functional outcome after ischemic stroke, while the underlying mechanisms need further investigation.

Microglia, the major resident immune cells in the central nervous system, serve as the frontline soldiers against cerebral ischemic injuries, possibly along with metabolic alterations. However, signaling pathways involved in the regulation of microglial immunometabolism in ischemic stroke remain to be further elucidated. In this study, using single-nuclei RNA sequencing, a microglial subcluster up-regulated in ischemic brain tissues is identified, with high expression of Igf1 and Trem2, neuroprotective transcriptional signature and enhanced oxidative phosphorylation. Microglial depletion by PLX3397 exacerbates ischemic brain damage, which is reversed by repopulating the microglia with high Igf1 and Trem2 phenotype. Mechanistically, Igf1 serves as one of the major down-stream molecules of Trem2, and Trem2-Igf1 signaling axis regulates microglial functional and metabolic profiles, exerting neuroprotective effects on ischemic stroke. Overexpression of Igf1 and supplementation of cyclocreatine restore microglial glucometabolic levels and cellular functions even in the absence of Trem2. These findings suggest that Trem2-Igf1 signaling axis reprograms microglial immunometabolic profiles and shifts microglia toward a neuroprotective phenotype, which has promising therapeutic potential in treating ischemic stroke., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Ischemic stroke is caused primarily by an interruption in cerebral blood flow, which induces severe neural injuries, and is one of the leading causes of death and disability worldwide. Thus, it is of great necessity to further detailly elucidate the mechanisms of ischemic stroke and find out new therapies against the disease. In recent years, efforts have been made to understand the pathophysiology of ischemic stroke, including cellular excitotoxicity, oxidative stress, cell death processes, and neuroinflammation. In the meantime, a plethora of signaling pathways, either detrimental or neuroprotective, are also highly involved in the forementioned pathophysiology. These pathways are closely intertwined and form a complex signaling network. Also, these signaling pathways reveal therapeutic potential, as targeting these signaling pathways could possibly serve as therapeutic approaches against ischemic stroke. In this review, we describe the signaling pathways involved in ischemic stroke and categorize them based on the pathophysiological processes they participate in. Therapeutic approaches targeting these signaling pathways, which are associated with the pathophysiology mentioned above, are also discussed. Meanwhile, clinical trials regarding ischemic stroke, which potentially target the pathophysiology and the signaling pathways involved, are summarized in details. Conclusively, this review elucidated potential molecular mechanisms and related signaling pathways underlying ischemic stroke, and summarize the therapeutic approaches targeted various pathophysiology, with particular reference to clinical trials and future prospects for treating ischemic stroke., (© 2022. The Author(s).)