Activation and Role of Astrocytes in Ischemic Stroke

Astrocyte modulation in cerebral ischemia-reperfusion injury: A promising therapeutic strategy

Cerebral ischemia-reperfusion injury (CIRI) poses significant challenges for drug development due to its complex pathogenesis. Astrocyte involvement in CIRI pathogenesis has led to the development of novel astrocyte-targeting drug strategies. To comprehensively review the current literature, we conducted a thorough analysis from January 2012 to December 2023, identifying 82 drugs aimed at preventing and treating CIRI. These drugs target astrocytes to exert potential benefits in CIRI, and their primary actions include modulation of relevant signaling pathways to inhibit neuroinflammation and oxidative stress, reduce cerebral edema, restore blood-brain barrier integrity, suppress excitotoxicity, and regulate autophagy. Notably, active components from traditional Chinese medicines (TCM) such as Salvia miltiorrhiza, Ginkgo, and Ginseng exhibit these important pharmacological properties and show promise in the treatment of CIRI. This review highlights the potential of astrocyte-targeted drugs to ameliorate CIRI and categorizes them based on their mechanisms of action, underscoring their therapeutic potential in targeting astrocytes.

Distinct brain morphometry patterns revealed by deep learning improve prediction of post-stroke aphasia severity

BACKGROUND

Emerging evidence suggests that post-stroke aphasia severity depends on the integrity of the brain beyond the lesion. While measures of lesion anatomy and brain integrity combine synergistically to explain aphasic symptoms, substantial interindividual variability remains unaccounted. One explanatory factor may be the spatial distribution of morphometry beyond the lesion (e.g., atrophy), including not just specific brain areas, but distinct three-dimensional patterns.

METHODS

Here, we test whether deep learning with Convolutional Neural Networks (CNNs) on whole brain morphometry (i.e., segmented tissue volumes) and lesion anatomy better predicts chronic stroke individuals with severe aphasia (N = 231) than classical machine learning (Support Vector Machines; SVMs), evaluating whether encoding spatial dependencies identifies uniquely predictive patterns.

RESULTS

CNNs achieve higher balanced accuracy and F1 scores, even when SVMs are nonlinear or integrate linear or nonlinear dimensionality reduction. Parity only occurs when SVMs access features learned by CNNs. Saliency maps demonstrate that CNNs leverage distributed morphometry patterns, whereas SVMs focus on the area around the lesion. Ensemble clustering of CNN saliencies reveals distinct morphometry patterns unrelated to lesion size, consistent across individuals, and which implicate unique networks associated with different cognitive processes as measured by the wider neuroimaging literature. Individualized predictions depend on both ipsilateral and contralateral features outside the lesion.

CONCLUSIONS

Three-dimensional network distributions of morphometry are directly associated with aphasia severity, underscoring the potential for CNNs to improve outcome prognostication from neuroimaging data, and highlighting the prospective benefits of interrogating spatial dependence at different scales in multivariate feature space.

H2S Regulates the Phenotypic Transformation of Astrocytes Following Cerebral Ischemia/Reperfusion via Inhibiting the RhoA/ROCK Pathway

The role of hydrogen sulfide (H2S) on the phenotypic change of astrocytes following cerebral ischemia/reperfusion (I/R) in mice was investigated in present study. We tested the expression of glial fibrillary acidic protein (GFAP), A2 phenotype marker S100a10, and A1 phenotype marker C3 protein and assessed the change of BrdU/GFAP-positive cells, GFAP/C3-positive cells, and GFAP/S100a10-positive cells in mice hippocampal tissues to evaluate the change of astrocyte phenotypes following cerebral I/R. The role of H2S on the phenotypic change of astrocytes following cerebral I/R in mice was investigated by using H2S synthase cystathionine-γ-lyase (CSE) knockout mice (KO). The results revealed that cerebral I/R injury promoted the astrocytes proliferation of both A1 and A2 phenotypes, which were more significant in mice of H2S synthase CSE KO than in mice of wild type (WT). Interestingly, supplement with H2S could inhibit the A1 phenotype proliferation but promote the proliferation of A2 phenotype, suggesting that H2S could regulate the transformation of astrocytes to A2 phenotype following cerebral I/R, which is beneficial for neuronal recovery. Besides, we found that H2S-mediated change of astrocyte phenotype is related to inhibiting the RhoA/ROCK pathway. Furthermore, both H2S and ROCK inhibitor could ameliorate the brain injury of mice at 9 days after cerebral I/R. In conclusion, H2S regulates the phenotypic transformation of astrocytes to A2 phenotype following the cerebral I/R via inhibiting RhoA/ROCK pathway and then exerts the neuroprotective effect against the subacute brain injury.

Longitudinal microstructural alterations surrounding subcortical ischemic stroke lesions detected by free-water imaging

In this study we explore the spatio-temporal trajectory and clinical relevance of microstructural white matter changes within and beyond subcortical stroke lesions detected by free-water imaging. Twenty-seven patients with subcortical infarct with mean age of 66.73 (SD 11.57) and median initial NIHSS score of 4 (IQR 3-7) received diffusion MRI 3-5 days, 1 month, 3 months, and 12 months after symptom-onset. Extracellular free-water and fractional anisotropy of the tissue (FAT) were averaged within stroke lesions and the surrounding tissue. Linear models showed increased free-water and decreased FAT in the white matter of patients with subcortical stroke (lesion [free-water/FAT, mean relative difference in %, ipsilesional vs. contralesional hemisphere at 3-5 days, 1 month, 3 months, and 12 months after symptom-onset]: +41/-34, +111/-37, +208/-26, +251/-18; perilesional tissue [range in %]: +[5-24]/-[0.2-7], +[2-20]/-[3-16], +[5-43]/-[2-16], +[10-110]/-[2-12]). Microstructural changes were most prominent within the lesion and gradually became less pronounced with increasing distance from the lesion. While free-water elevations continuously increased over time and peaked after 12 months, FAT decreases were most evident 1 month post-stroke, gradually returning to baseline values thereafter. Higher perilesional free-water and higher lesional FAT at baseline were correlated with greater reductions in lesion size (rho = -0.51, p = .03) in unadjusted analyses only, while there were no associations with clinical measures. In summary, we find a characteristic spatio-temporal pattern of extracellular and cellular alterations beyond subcortical stroke lesions, indicating a dynamic parenchymal response to ischemia characterized by vasogenic edema, cellular damage, and white matter atrophy.

A role for astrocytic insulin-like growth factor I receptors in the response to ischemic insult

Increased neurotrophic support, including insulin-like growth factor I (IGF-I), is an important aspect of the adaptive response to ischemic insult. However, recent findings indicate that the IGF-I receptor (IGF-IR) in neurons plays a detrimental role in the response to stroke. Thus, we investigated the role of astrocytic IGF-IR on ischemic insults using tamoxifen-regulated Cre deletion of IGF-IR in glial fibrillary acidic protein (GFAP) astrocytes, a major cellular component in the response to injury. Ablation of IGF-IR in astrocytes (GFAP-IGF-IR KO mice) resulted in larger ischemic lesions, greater blood-brain-barrier disruption and more deteriorated sensorimotor coordination. RNAseq detected increases in inflammatory, cell adhesion and angiogenic pathways, while the expression of various classical biomarkers of response to ischemic lesion were significantly increased at the lesion site compared to control littermates. While serum IGF-I levels after injury were decreased in both control and GFAP-IR KO mice, brain IGF-I mRNA expression show larger increases in the latter. Further, greater damage was also accompanied by altered glial reactivity as reflected by changes in the morphology of GFAP astrocytes, and relative abundance of ionized calcium binding adaptor molecule 1 (Iba 1) microglia. These results suggest a protective role for astrocytic IGF-IR in the response to ischemic injury.

Neurodegenerative Diseases: Unraveling the Heterogeneity of Astrocytes

The astrocyte population, around 50% of human brain cells, plays a crucial role in maintaining the overall health and functionality of the central nervous system (CNS). Astrocytes are vital in orchestrating neuronal development by releasing synaptogenic molecules and eliminating excessive synapses. They also modulate neuronal excitability and contribute to CNS homeostasis, promoting neuronal survival by clearance of neurotransmitters, transporting metabolites, and secreting trophic factors. Astrocytes are highly heterogeneous and respond to CNS injuries and diseases through a process known as reactive astrogliosis, which can contribute to both inflammation and its resolution. Recent evidence has revealed remarkable alterations in astrocyte transcriptomes in response to several diseases, identifying at least two distinct phenotypes called A1 or neurotoxic and A2 or neuroprotective astrocytes. However, due to the vast heterogeneity of these cells, it is limited to classify them into only two phenotypes. This review explores the various physiological and pathophysiological roles, potential markers, and pathways that might be activated in different astrocytic phenotypes. Furthermore, we discuss the astrocyte heterogeneity in the main neurodegenerative diseases and identify potential therapeutic strategies. Understanding the underlying mechanisms in the differentiation and imbalance of the astrocytic population will allow the identification of specific biomarkers and timely therapeutic approaches in various neurodegenerative diseases.

MSC Promotes the Secretion of Exosomal lncRNA KLF3-AS1 to Regulate Sphk1 Through YY1-Musashi-1 Axis and Improve Cerebral Ischemia-Reperfusion Injury

Stroke remains the 3rd leading cause of long-term disability globally. Over the past decade, mesenchymal stem cell (MSC) transplantation has been proven as an effective therapy for ischemic stroke. However, the mechanism of MSC-derived exosomal lncRNAs during cerebral ischemia/reperfusion (I/R) remains ambiguous. The oxygen-glucose deprivation/reoxygenation (OGD/R) and middle cerebral artery occlusion (MCAO) rat model were generated. MSCs were isolated and characterized by flow cytometry and histochemical staining, and MSC exosomes were purified and characterized by transmission electron microscopy, flow cytometry and Western blot. Western blot, RT-qPCR and ELISA assay were employed to examine the expression or secretion of key molecules. CCK-8 and TUNEL assays were used to assess cell viability and apoptosis. RNA immunoprecipitation and RNA pull-down were used to investigate the direct association between krüppel-like factor 3 antisense RNA 1 (KLF3-AS1) and musashi-1(MSI1). Yin Yang 1 (YY1)-mediated transcriptional regulation was assessed by chromatin immunoprecipitation and luciferase assays. The histological changes and immunoreactivity of key molecules in brain tissues were examined by H&E and immunohistochemistry. MSCs were successfully isolated and exhibited directionally differential potentials. MSC exosomal KLF3-AS1 alleviated OGD/R-induced inflammation in SK-N-SH and SH-SY5Y cells via modulating Sphk1. Mechanistical studies showed that MSI1 positively regulated KLF3-AS1 expression through its direct binding to KLF3-AS1. YY1 was identified as a transcription activator of MSI1 in MSCs. Functionally, YY1/MSI1 axis regulated the release of MSC exosomal KLF3-AS1 to modulate sphingosine kinase 1 (Sphk1)/NF-κB pathway, thereby ameliorating OGD/R- or cerebral I/R-induced injury. MSCs promote the release of exosomal KLF3-AS1 to regulate Sphk1 through YY1/MSI axis and improve cerebral I/R injury.

Transcriptome Analysis Reveals Dynamic Microglial-Induced A1 Astrocyte Reactivity via C3/C3aR/NF-κB Signaling After Ischemic Stroke

Microglia and astrocytes are key players in neuroinflammation and ischemic stroke. A1 astrocytes are a subtype of astrocytes that are extremely neurotoxic and quickly kill neurons. Although the detrimental A1 astrocytes are present in many neurodegenerative diseases and are considered to accelerate neurodegeneration, their role in the pathophysiology of ischemic stroke is poorly understood. Here, we combined RNA-seq, molecular and immunological techniques, and behavioral tests to investigate the role of A1 astrocytes in the pathophysiology of ischemic stroke. We found that astrocyte phenotypes change from a beneficial A2 type in the acute phase to a detrimental A1 type in the chronic phase following ischemic stroke. The activated microglial IL1α, TNF, and C1q prompt commitment of A1 astrocytes. Inhibition of A1 astrocytes induction attenuates reactive gliosis and ameliorates morphological and functional defects following ischemic stroke. The crosstalk between astrocytic C3 and microglial C3aR contributes to the formation of A1 astrocytes and morphological and functional defects. In addition, NF-κB is activated following ischemic stroke and governs the formation of A1 astrocytes via direct targeting of inflammatory cytokines and chemokines. Taken together, we discovered that A2 astrocytes and A1 astrocytes are enriched in the acute and chronic phases of ischemic stroke respectively, and that the C3/C3aR/NF-κB signaling leads to A1 astrocytes induction. Therefore, the C3/C3aR/NF-κB signaling is a novel therapeutic target for ischemic stroke treatment.

The beneficial health effects of puerarin in the treatment of cardiovascular diseases: from mechanisms to therapeutics

Cardiovascular diseases (CVDs) are the leading causes of death globally that seriously threaten human health. Although novel western medicines have continued to be discovered over the past few decades to inhibit the progression of CVDs, new drug research and development for treating CVDs with less side effects and adverse reactions are continuously being desired. Puerarin is a natural product found in a variety of medicinal plants belonging to the flavonoid family with potent biological and pharmacological activities. Abundant research findings in the literature have suggested that puerarin possesses a promising prospect in treating CVDs. In recent years, numerous new molecular mechanisms of puerarin have been explored in experimental and clinical studies, providing new evidence for this plant metabolite to protect against CVDs. This article systematically introduces the history of use, bioavailability, and various dosage forms of puerarin and further summarizes recently published data on the major research advances and their underlying therapeutic mechanisms in treating CVDs. It may provide references for researchers in the fields of pharmacology, natural products, and internal medicine.

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

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

Lactate protects neurons and astrocytes against ischemic injury by modulating Ca2+ homeostasis and inflammatory response

Lactate is now considered an additional fuel or signaling molecule in the brain. In this study, using an oxygen-glucose deprivation (OGD) model, we found that treatment with lactate inhibited the global increase in intracellular calcium ion concentration ([Ca2+]) in neurons and astrocytes, decreased the percentage of dying cells, and caused a metabolic shift in astrocytes and neurons toward aerobic oxidation of substrates. OGD resulted in proinflammatory changes and increased expression of cytokines and chemokines, whereas incubation with lactate reduced these changes. Pure astrocyte cultures were less sensitive than neuroglia cultures during OGD. Astrocytes exposed to lipopolysaccharide (LPS) also showed pro-inflammatory changes that were reduced by incubation with lactate. Our study suggests that lactate may have neuroprotective effects under ischemic and inflammatory conditions.

The role of neuroglial cells communication in ischemic stroke

Ischemic stroke is one of the leading causes of death and disability globally, but its treatment options are limited due to therapeutic window and reperfusion injury constraints. Microglia, astrocytes, and oligodendrocytes are the major components of the neurovascular unit, and there is substantial evidence suggesting their contributions to maintaining homeostasis in the central nervous system. Neuroglial cells participate in neuronal physiological functions and the repair of damaged neurons through various communication methods, including gap junctions, chemical signaling, and extracellular vesicles, in conjunction with other components of the neurovascular unit. Ischemia-induced microglia and astrocytes polarize into "M1/M2" and "A1/A2" phenotypes and exert neurotoxic or neuroprotective effects by releasing soluble factors, secreting extracellular vesicles, and forming syncytia networks in the acute (<72 h), subacute (>72 h), and chronic phases (>6 weeks). Apoptosis of oligodendrocytes due to ischemic hypoxia leads to white matter injury, causing long-term cognitive dysfunction, and promoting oligodendrogenesis is a crucial direction for achieving functional recovery in ischemic stroke. In this article, we summarize the cellular interactions following cerebral ischemia, analyze the roles of neuroglial cells through gap junctions, chemical signaling, and extracellular vesicles in different stages of ischemic stroke, and further explore strategies for intervening in ischemic stroke.

Retinoic acid attenuates ischemic injury-induced activation of glial cells and inflammatory factors in a rat stroke model

Stroke is a leading cause of death and long-term disability which can cause oxidative damage and inflammation of the neuronal cells. Retinoic acid is an active metabolite of vitamin A that has various beneficial effects including antioxidant and anti-inflammatory effects. In this study, we investigated whether retinoic acid modulates oxidative stress and inflammatory factors in a stroke animal model. A middle cerebral artery occlusion (MCAO) was performed on adult male rats to induce focal cerebral ischemia. Retinoic acid (5 mg/kg) or vehicle was injected into the peritoneal cavity for four days before MCAO surgery. The neurobehavioral tests were carried out 24 h after MCAO and cerebral cortex tissues were collected. The cortical damage was assessed by hematoxylin-eosin staining and reactive oxygen species assay. In addition, Western blot and immunohistochemical staining were performed to investigate the activation of glial cells and inflammatory cytokines in MCAO animals. Ionized calcium-binding adapter molecule-1 (Iba-1) and glial fibrillary acidic protein (GFAP) were used as markers of microglial and astrocyte activation, respectively. Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were used as representative pro-inflammatory cytokines. Results showed that MCAO damage caused neurobehavioral defects and histopathological changes in the ischemic region and increased oxidative stress. Retinoic acid treatment reduced these changes caused by MCAO damage. We detected increases in Iba-1 and GFAP in MCAO animals treated with vehicle. However, retinoic acid alleviated increases in Iba-1 and GFAP caused by MCAO damage. Moreover, MCAO increased levels of nuclear factor-κB and pro-inflammatory cytokines, including TNF-α and IL-1β. Retinoic acid alleviated the expression of these inflammatory proteins. These findings elucidate that retinoic acid regulates microglia and astrocyte activation and modulates pro-inflammatory cytokines. Therefore, this study suggests that retinoic acid exhibits strong antioxidant and anti-inflammatory properties by reducing oxidative stress, inhibiting neuroglia cell activation, and preventing the increase of pro-inflammatory cytokines in a cerebral ischemia.

Mechanism of scutellarin inhibition of astrocyte activation to type A1 after ischemic stroke

OBJECTIVE

The aim of this study was to investigate the effects of scutellarin on the activation of astrocytes into the A1 type following cerebral ischemia and to explore the underlying mechanism.

METHODS

In vivo, a mouse middle cerebral artery wire embolism model was established to observe the regulation of astrocyte activation to A1 type by scutellarin, and the effects on neurological function and brain infarct volume. In vitro, primary astrocytes were cultured to establish an oxygen-glucose deprivation model, and the mRNA and protein expression of C3, a specific marker of A1-type astrocytes pretreated with scutellarin, were examined. The neurons were cultured in vitro to detect the toxic effects of ischemia-hypoxia-activated A1 astrocyte secretion products on neurons, and to observe whether scutellarin could reduce the neurotoxicity of A1 astrocytes. To validate the signaling pathway-related proteins regulated by scutellarin on C3 expression in astrocytes.

RESULTS

The results showed that scutellarin treatment reduced the volume of cerebral infarcts and attenuated neurological deficits in mice caused by middle cerebral artery embolism. Immunofluorescence and Western blot showed that treatment with scutellarin down-regulated middle cerebral artery embolism and OGD/R up-regulated A1-type astrocyte marker C3. The secretory products of ischemia-hypoxia-activated A1-type astrocytes were toxic to neurons and induced an increase in neuronal apoptosis, and astrocytes treated with scutellarin reduced the toxic effects on neurons. Further study revealed that scutellarin inhibited the activation of NF-κB signaling pathway and thus inhibited the activation of astrocytes to A1 type.

Unravelling the Road to Recovery: Mechanisms of Wnt Signalling in Spinal Cord Injury

Spinal cord injury (SCI) is a complex neurodegenerative pathology that consistently harbours a poor prognostic outcome. At present, there are few therapeutic strategies that can halt neuronal cell death and facilitate functional motor recovery. However, recent studies have highlighted the Wnt pathway as a key promoter of axon regeneration following central nervous system (CNS) injuries. Emerging evidence also suggests that the temporal dysregulation of Wnt may drive cell death post-SCI. A major challenge in SCI treatment resides in developing therapeutics that can effectively target inflammation and facilitate glial scar repair. Before Wnt signalling is exploited for SCI therapy, further research is needed to clarify the implications of Wnt on neuroinflammation during chronic stages of injury. In this review, an attempt is made to dissect the impact of canonical and non-canonical Wnt pathways in relation to individual aspects of glial and fibrotic scar formation. Furthermore, it is also highlighted how modulating Wnt activity at chronic time points may aid in limiting lesion expansion and promoting axonal repair.

Corticospinal tract: a new hope for the treatment of post-stroke spasticity

Stroke is the third leading cause of death and disability worldwide. Post-stroke spasticity (PSS) is the most common complication of stroke but represents only one of the many manifestations of upper motor neuron syndrome. As an upper motor neuron, the corticospinal tract (CST) is the only direct descending motor pathway that innervates the spinal motor neurons and is closely related to the recovery of limb function in patients with PSS. Therefore, promoting axonal remodeling in the CST may help identify new therapeutic strategies for PSS. In this review, we outline the pathological mechanisms of PSS, specifically their relationship with CST, and therapeutic strategies for axonal regeneration of the CST after stroke. We found it to be closely associated with astroglial scarring produced by astrocyte activation and its secretion of neurotrophic factors, mainly after the onset of cerebral ischemia. We hope that this review offers insight into the relationship between CST and PSS and provides a basis for further studies.

The Role of Circadian Rhythms in Stroke: A Narrative Review

Stroke, a debilitating condition often leading to long-term disability, poses a substantial global concern and formidable challenge. The increasing incidence of stroke has drawn the attention of medical researchers and neurologists worldwide. Circadian rhythms have emerged as pivotal factors influencing stroke's onset, pathogenesis, treatment, and outcomes. To gain deeper insights into stroke, it is imperative to explore the intricate connection between circadian rhythms and stroke, spanning from molecular mechanisms to pathophysiological processes. Despite existing studies linking circadian rhythm to stroke onset, there remains a paucity of comprehensive reviews exploring its role in pathogenesis, treatment, and prognosis. This review undertakes a narrative analysis of studies investigating the relationship between circadian variation and stroke onset. It delves into the roles of various physiological factors, including blood pressure, coagulation profiles, blood cells, catecholamines, cortisol, and the timing of antihypertensive medication, which contribute to variations in circadian-related stroke risk. At a molecular level, the review elucidates the involvement of melatonin, circadian genes, and glial cells in the pathophysiology. Furthermore, it provides insights into the diverse factors influencing stroke treatment and outcomes within the context of circadian variation. The review underscores the importance of considering circadian rhythms when determining the timing of stroke interventions, emphasizing the necessity for personalized stroke management strategies that incorporate circadian rhythms. It offers valuable insights into potential molecular targets and highlights areas that require further exploration to enhance our understanding of the underlying pathophysiology. In comparison to the published literature, this manuscript distinguishes itself through its coverage of circadian rhythms' impact on stroke across the entire clinical spectrum. It presents a unique synthesis of epidemiological, clinical, molecular, and cellular evidence, underscoring their collective significance.

PRDX6-iPLA2 aggravates neuroinflammation after ischemic stroke via regulating astrocytes-induced M1 microglia

The crosstalk between astrocytes and microglia plays a pivotal role in neuroinflammation following ischemic stroke, and phenotypic distribution of these cells can change with the progression of ischemic stroke. Peroxiredoxin (PRDX) 6 phospholipase A2 (iPLA2) activity is involved in the generation of reactive oxygen species(ROS), with ROS driving the activation of microglia and astrocytes; however, its exact function remains unexplored. MJ33, PRDX6D140A mutation was used to block PRDX6-iPLA2 activity in vitro and vivo after ischemic stroke. PRDX6T177A mutation was used to block the phosphorylation of PRDX6 in CTX-TNA2 cell lines. NAC, GSK2795039, Mdivi-1, U0126, and SB202190 were used to block the activity of ROS, NOX2, mitochondrial fission, ERK, and P38, respectively, in CTX-TNA2 cells. In ischemic stroke, PRDX6 is mainly expressed in astrocytes and PRDX6-iPLA2 is involved in the activation of astrocytes and microglia. In co-culture system, Asp140 mutation in PRDX6 of CTX-TNA2 inhibited the polarization of microglia, reduced the production of ROS, suppressed NOX2 activation, and inhibited the Drp1-dependent mitochondrial fission following OGD/R. These effects were further strengthened by the inhibition of ROS production. In subsequent experiments, U0126 and SB202190 inhibited the phosphorylation of PRDX6 at Thr177 and reduced PRDX6-iPLA2 activity. These results suggest that PRDX6-iPLA2 plays an important role in the astrocyte-induced generation of ROS and activation of microglia, which are regulated by the activation of Nox2 and Drp1-dependent mitochondrial fission pathways. Additionally, PRDX6-iPLA2 activity is regulated by MAPKs via the phosphorylation of PRDX6 at Thr177 in astrocytes.

Astroglial Cells: Emerging Therapeutic Targets in the Management of Traumatic Brain Injury

Traumatic Brain Injury (TBI) represents a significant health concern, necessitating advanced therapeutic interventions. This detailed review explores the critical roles of astrocytes, key cellular constituents of the central nervous system (CNS), in both the pathophysiology and possible rehabilitation of TBI. Following injury, astrocytes exhibit reactive transformations, differentiating into pro-inflammatory (A1) and neuroprotective (A2) phenotypes. This paper elucidates the interactions of astrocytes with neurons, their role in neuroinflammation, and the potential for their therapeutic exploitation. Emphasized strategies encompass the utilization of endocannabinoid and calcium signaling pathways, hormone-based treatments like 17β-estradiol, biological therapies employing anti-HBGB1 monoclonal antibodies, gene therapy targeting Connexin 43, and the innovative technique of astrocyte transplantation as a means to repair damaged neural tissues.

Effect of Combination Electroacupuncture and Tenuigenin on the Migration and Differentiation of Mesenchymal Stem Cells following Ischemic Stroke

Objectives

Since stroke is a serious health issue, novel therapeutic strategies are required. In a mouse model of ischemic stroke, this study analyzed the potential of electroacupuncture (EA) and tenuigenin (TE) to improve the efficacy of human mesenchymal stem cell (hMSC) transplantation.

Methods

Middle cerebral artery occlusion (MCAO) with reperfusion was used to generate ischemic stroke. Forty-eight male C57BL/6 mice were randomly divided into five groups control, MCAO-operated, MCAO-EA, MCAO-TE, or MCAO + EA + TE. Subsequently, hMSCs were transplanted into the ischemic region and EA, TE, or the combination was administered. Behavior assessments and immunohistochemistry were conducted to evaluate motor and cognitive recovery and hMSCs survival, migration, and differentiation.

Results

The combined treatment of EA and TE exhibited enhanced hMSCs survival, migration and differentiation into neural cell lineages while suppressing astrocyte formation. Immunohistochemistry demonstrated increased neurogenesis through hMSCs transplantation in the ischemic brain. Immediate behavioral improvements were not significantly different between groups, but there was a gradual recovery in motor and cognitive function over time.

Conclusion

These findings highlight the potential of EA and TE co-treatment as a therapeutic strategy for ischemic stroke, opening avenues for further research to optimize treatment protocols and elucidate underlying mechanisms.

Single nucleus RNA sequencing reveals glial cell type-specific responses to ischemic stroke

Reactive neuroglia critically shape the braińs response to ischemic stroke. However, their phenotypic heterogeneity impedes a holistic understanding of the cellular composition and microenvironment of the early ischemic lesion. Here we generated a single cell resolution transcriptomics dataset of the injured brain during the acute recovery from permanent middle cerebral artery occlusion. This approach unveiled infarction and subtype specific molecular signatures in oligodendrocyte lineage cells and astrocytes, which ranged among the most transcriptionally perturbed cell types in our dataset. Specifically, we characterized and compared infarction restricted proliferating oligodendrocyte precursor cells (OPCs), mature oligodendrocytes and heterogeneous reactive astrocyte populations. Our analyses unveiled unexpected commonalities in the transcriptional response of oligodendrocyte lineage cells and astrocytes to ischemic injury. Moreover, OPCs and reactive astrocytes were involved in a shared immuno-glial cross talk with stroke specific myeloid cells. In situ, osteopontin positive myeloid cells accumulated in close proximity to proliferating OPCs and reactive astrocytes, which expressed the osteopontin receptor CD44, within the perilesional zone specifically. In vitro, osteopontin increased the migratory capacity of OPCs. Collectively, our study highlights molecular cross talk events which might govern the cellular composition and microenvironment of infarcted brain tissue in the early stages of recovery.

Leukemia-derived Exosomes Can Induce Responses Related to Tumorigenesis on Non-tumoral Astrocytes

Cancer is the second cause of disability and death worldwide. Identifying communication between cancer cells and normal cells can shed light on the underlying metastatic mechanisms. Among different suspected mechanisms, exosomes derived from cancer cells have been introduced as a main key player in metastatic processes. To this point, we evaluated the effects of exosomes derived from the leukemia nalm6 cell line on astrocytes behavior, such as proliferation and inflammatory pathways. To assess astrocyte responses, data were obtained by MTT, Annexin/PI to indicate proliferation and apoptosis. Further analyses were performed by Real-time PCR and western blot to assess the expression of IL6, IL1β, NFkβ, TNFα, and aquaporin-4 (AQP4). Our results demonstrated that the proliferation of astrocytes was significantly increased when treated with exosomes derived from Nalm6 cells. We also found that the expression of IL6, IL1β, NFkβ, and TNFα were significantly increased at the mRNA level when exposed to exosomes derived from Nalm6 cells. Finally, the mRNA and protein levels of AQP4 were profoundly increased after being treated by exosomes derived from Nalm6 cells. To sum up, our data indicated that the secretion of cancer cells could induce responses related to tumorigenesis. However, further studies on this topic are warranted to clarify exosomes' role in metastasis.

Exosomal miRNAs as Biomarkers of Ischemic Stroke

Exosomes are small lipid bilayer membrane particles released from all living cells into the extracellular environment. They carry several molecules and have a critical role in cell-cell communication under physiological and pathological conditions. In recent decades, exosomes, and especially their cargo, have emerged as a promising tool for several clinical conditions. However, the literature has become increasingly unambiguous in defining the role of exosomes in chronic cerebrovascular diseases. Because they can pass through the blood-brain barrier, they have great potential to reflect intracerebral changes. They can, thus, provide valuable insight into the mechanisms of central nervous system diseases. The purpose of this review is to describe the literature on the role of exosomal miRNA, which represents the most widely investigated exosomal biomarker, in strokes. First, we provide an overview of exosomes, from biology to isolation and characterization. Then, we describe the relationship between exosomes and stroke pathogenesis. Finally, we summarize the human studies evaluating exosomal miRNA biomarkers of stroke. Although the collective literature supports the potential use of exosomal miRNA as biomarkers of ischemic stroke, there are still several limitations hampering their introduction into clinical practice.

Brain-Heart Axis: Brain-Derived Neurotrophic Factor and Cardiovascular Disease-A Review of Systematic Reviews

BACKGROUND

The brain-heart axis is an intra- and bidirectional complex that links central nervous system dysfunction and cardiac dysfunction. In recent decades, brain-derived neurotrophic factor (BDNF) has emerged as a strategic molecule involved in both brain and cardiovascular disease (CVD). This systematic review of systematic reviews aimed to (1) identify and summarize the evidence for the BDNF genotype and BDNF concentration in CVD risk assessment, (2) evaluate the evidence for the use of BDNF as a biomarker of CVD recovery, and (3) evaluate rehabilitation approaches that can restore BDNF concentration.

METHODS

A comprehensive search strategy was developed using PRISMA. The risk of bias was assessed via ROBIS.

RESULTS

Seven studies were identified, most of which aimed to evaluate the role of BDNF in stroke patients. Only two systematic reviews examined the association of BDNF concentration and polymorphism in CVDs other than stroke.

CONCLUSIONS

The overall evidence showed that BDNF plays a fundamental role in assessing the risk of CVD occurrence, because lower BDNF concentrations and rs6265 polymorphism are often associated with CVD. Nevertheless, much work remains to be carried out in current research to investigate how BDNF is modulated in different cardiovascular diseases and in different populations.

TRP Channels in Stroke

Ischemic stroke is a devastating disease that affects millions of patients worldwide. Unfortunately, there are no effective medications for mitigating brain injury after ischemic stroke. TRP channels are evolutionally ancient biosensors that detect external stimuli as well as tissue or cellular injury. To date, many members of the TRP superfamily have been reported to contribute to ischemic brain injury, including the TRPC subfamily (1, 3, 4, 5, 6, 7), TRPV subfamily (1, 2, 3, 4) and TRPM subfamily (2, 4, 7). These TRP channels share structural similarities but have distinct channel functions and properties. Their activation during ischemic stroke can be beneficial, detrimental, or even both. In this review, we focus on discussing the interesting features of stroke-related TRP channels and summarizing the underlying cellular and molecular mechanisms responsible for their involvement in ischemic brain injury.

A2A adenosine receptor-driven cAMP signaling in olfactory bulb astrocytes is unaffected in experimental autoimmune encephalomyelitis

Introduction

The cyclic nucleotide cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger, which is known to play an important anti-inflammatory role. Astrocytes in the central nervous system (CNS) can modulate inflammation but little is known about the significance of cAMP in their function.

Methods

We investigated cAMP dynamics in mouse olfactory bulb astrocytes in brain slices prepared from healthy and experimental autoimmune encephalomyelitis (EAE) mice.

Results

The purinergic receptor ligands adenosine and adenosine triphosphate (ATP) both induced transient increases in cAMP in astrocytes expressing the genetically encoded cAMP sensor Flamindo2. The A2A receptor antagonist ZM241385 inhibited the responses. Similar transient increases in astrocytic cAMP occurred when olfactory receptor neurons were stimulated electrically, resulting in ATP release from the stimulated axons that increased cAMP, again via A2A receptors. Notably, A2A-mediated responses to ATP and adenosine were not different in EAE mice as compared to healthy mice.

Discussion

Our results indicate that ATP, synaptically released by afferent axons in the olfactory bulb, is degraded to adenosine that acts on A2A receptors in astrocytes, thereby increasing the cytosolic cAMP concentration. However, this pathway is not altered in the olfactory bulb of EAE mice.

Synthesis of 1,3,5-triphenyl-1,2,4-triazole derivatives and their neuroprotection by anti-oxidative stress and anti-inflammation and protecting BBB

Acute ischemic stroke (AIS) is a serious cardiovascular and cerebrovascular disease; Oxidative stress and neuroinflammation are important factors which destroy blood-brain barrier (BBB) in AIS. In the study, a series of 1,3,5-triphenyl-1,2,4-triazole derivatives were designed and synthesized; the optimal compound 9 was obtained by screening their anti-oxidant and anti-inflammatory effects; the neuroprotection effect of compound 9 was evaluated with a rat middle cerebral artery occlusion (MCAO) model. Subsequently, the mechanism of neuroprotection were explored via Western blot. The results prompt compound 9 maybe exert anti-AIS neuroprotection by inhibiting oxidative stress and neuroinflammation inhibition by inhibiting Keap1, COX-2 and iNOS. At the same time, it can protect BBB by reducing glycocalyx degradation and matrix metallopeptidase-9 levels. Its LD50 > 1000 mg/kg on mice and hERG channel inhibition IC50 > 30 μM, which lower acute toxicity and hERG channel inhibition would make compound 9 a promising stroke treatment candidate.

Early-life noise exposure causes cognitive impairment in a sex-dependent manner by disrupting homeostasis of the microbiota-gut-brain axis

Epidemiological investigations show that noise exposure in early life is associated with health and cognitive impairment. The gut microbiome established in early life plays a crucial role in modulating developmental processes that subsequently affect brain function and behavior. Here, we examined the impact of early-life exposure to noise on cognitive function in adolescent rats by analyzing the gut microbiome and metabolome to elucidate the underlying mechanisms. Chronic noise exposure during early life led to cognitive deficits, hippocampal injury, and neuroinflammation. Early-life noise exposure showed significant difference on the composition and function of the gut microbiome throughout adolescence, subsequently causing axis-series changes in fecal short-chain fatty acid (SCFA) metabolism and serum metabolome profiles, as well as dysregulation of endothelial tight junction proteins, in both intestine and brain. We also observed sex-dependent effects of microbiota depletion on SCFA-related beneficial bacteria in adolescence. Experiments on microbiota transplantation and SCFA supplementation further confirmed the role of intestinal bacteria and related SCFAs in early-life noise-exposure-induced impairments in cognition, epithelial integrity, and neuroinflammation. Overall, these results highlight the homeostatic imbalance of microbiota-gut-brain axis as an important physiological response toward environmental noise during early life and reveals subtle differences in molecular signaling processes between male and female rats.

Signaling pathways in brain ischemia: Mechanisms and therapeutic implications

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

Nrf2/HO-1 blocks TXNIP/NLRP3 interaction via elimination of ROS in oxygen-glucose deprivation-induced neuronal necroptosis

Acute ischemic stroke (AIS) is known to trigger a cascade of inflammatory events that induces secondary tissue damages. As a type of regulated inflammatory cell death, necroptosis is associated with AIS, whilst its regulation during neuroinflammation is not well understood. In particular, the actual function of NOD-like-receptor family pyrin domain-containing-3(NLRP3) inflammasome in cortical neuronal necroptosis still not clear. Herein, we explored the function of nuclear factor erythroid-2 related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) in oxygen-glucose deprivation (OGD) induced neuronal necroptosis and its underlying mechanism. To establish an in vitro model of neuronal necrosis, we used OGD/caspase-8 inhibitors (Q-VD-OPh, QVD) to treat rat primary cortical neurons (PCNs) after reoxygenation, wherein we found that the model cause an elevated ROS levels by mediating TXNIP/NLRP3 interactions, which in turn activated the NLRP3 inflammasome. Also, we observed that regulation of nuclear factor erythroid-2 related factor-2 (Nrf2) promoted heme oxygenase-1 (HO-1) expression and decreased TXNIP (a protein that relate oxidative stress to activation of inflammasome) and ROS levels, which negatively regulated the expression of OGD-induced activation of NLRP3 inflammasomes. In addition, HO-1 weakened NLRP3 inflammation body activation, which suggests that Nrf2-regulated HO-1 could block the interaction between TXNIP and NLRP3 in OGD/R-treated cortical neurons by inhibiting ROS production. Our study has discovered the importance of Nrf2/HO-1 signaling cascade for inhibiting inflammasome of NLRP3, which negatively regulated necrosis. Therefore, NLRP3 is considered a potential target for a novel neuroprotective approach, which can expand the therapeutic windows of stroke drugs.

Pterostilbene as a Therapeutic Alternative for Central Nervous System Disorders: A Review of the Current Status and Perspectives

Neurological disorders are diverse, have complex causes, and often result in disability; yet, effective treatments remain scarce. The resveratrol derivative pterostilbene possesses numerous physiological activities that hold promise as a novel therapy for the central nervous system (CNS) disorders. This review aimed to summarize the protective mechanisms of pterostilbene in in vitro and in vivo models of CNS disorders and the pharmacokinetics and safety to assess its possible effects on CNS disorders. Available evidence supports the protective effects of pterostilbene in CNS disorders involving mechanisms such as antioxidant and anti-inflammatory activity, regulation of lipid metabolism and vascular smooth muscle cell proliferation, improvement of synaptic function and neurogenesis, induction of glioma cell cycle arrest, and inhibition of glioma cell migration and invasion. Studies have identified possible molecular targets and pathways for the protective actions of pterostilbene in CNS disorders including the AMPK/STAT3, Akt, NF-κB, MAPK, and ERK signaling pathways. The possible pharmacological effects and molecular pathways of pterostilbene in CNS disorders are critically discussed in this review. Future studies should aim to increase our understanding of pterostilbene in animal models and humans to further evaluate its role in CNS disorders and the detailed mechanisms.

NPD1 Plus RvD1 Mediated Ischemic Stroke Penumbra Protection Increases Expression of Pro-homeostatic Microglial and Astrocyte Genes

Neuroprotection to attenuate or block the ischemic cascade and salvage neuronal damage has been extensively explored for treating ischemic stroke. However, despite increasing knowledge of the physiologic, mechanistic, and imaging characterizations of the ischemic penumbra, no effective neuroprotective therapy has been found. This study focuses on the neuroprotective bioactivity of docosanoid mediators: Neuroprotectin D1 (NPD1), Resolvin D1 (RvD1), and their combination in experimental stroke. Molecular targets of NPD1 and RvD1 are defined by following dose-response and therapeutic window. We demonstrated that treatment with NPD1, RvD1, and combination therapy provides high-grade neurobehavioral recovery and decreases ischemic core and penumbra volumes even when administered up to 6 h after stroke. The expression of the following genes was salient: (a) Cd163, an anti-inflammatory stroke-associated gene, was the most differentially expressed gene by NPD1+RvD1, displaying more than a 123-fold upregulation in the ipsilesional penumbra (Lisi et al., Neurosci Lett 645:106-112, 2017); (b) 100-fold upregulation takes place in astrocyte gene PTX3, a key regulator of neurogenesis and angiogenesis after cerebral ischemia (. Rodriguez-Grande et al., J Neuroinflammation 12:15, 2015); and (c) Tmem119 and P2y12, two markers of homeostatic microglia, were found to be enhanced by ten- and fivefold, respectively (Walker et al. Int J Mol Sci 21:678, 2020). Overall, we uncovered that protection after middle cerebral artery occlusion (MCAo) by the lipid mediators elicits expression of microglia and astrocyte-specific genes (Tmem119, Fcrls, Osmr, Msr1, Cd68, Cd163, Amigo2, Thbs1, and Tm4sf1) likely participating in enhancing homeostatic microglia, modulating neuroinflammation, promoting DAMP clearance, activating NPC differentiation and maturation, synapse integrity and contributing to cell survival.

Study on the Mechanism of Naoxintong in the Treatment of Cerebral Ischemia-Reperfusion Injury Based on a Multiomics Method

Cerebral ischemia-reperfusion (CIR) injury occurs as a secondary injury during the treatment of ischemic stroke (IS). There is a high death rate and morbidity due to IS throughout the world. Even though Naoxintong Capsule (NXT) is effective in the treatment of CIR, its mechanisms of action are unclear. The study aims to explore the clear mechanism associated with NXT therapy for CIR. We established the model of middle cerebral artery occlusion to evaluate the neurological function and assess the infarct size. Brain tissue metabolomics was used to identify different metabolites, and metabolic profiling systems enriched metabolic pathways. Then, the potential targets of NXT in the treatment of CIR were explored by proteomic, transcriptomic, and metabolomic methods. NXT improves CIR symptoms. We found potential 11 proteins and corresponding metabolites involved in NXT treatment of CIR. Most of these metabolites are regulated to restore after treatment. According to network pharmacology, we found 6 hub genes, including Glb1, Gmps, Pfas, Atic, Gaa, and Acox1, and their associated core metabolites and pathways. This study reveals the complex mechanism of NXT in treating CIR, and provides a new strategy for future researchers to screen related targets and pathways.

Neuroinflammation in Acute Ischemic and Hemorrhagic Stroke

PURPOSE OF REVIEW

This review aims to provide an overview of neuroinflammation in ischemic and hemorrhagic stroke, including recent findings on the mechanisms and cellular players involved in the inflammatory response to brain injury.

RECENT FINDINGS

Neuroinflammation is a crucial process following acute ischemic stroke (AIS) and hemorrhagic stroke (HS). In AIS, neuroinflammation is initiated within minutes of the ischemia onset and continues for several days. In HS, neuroinflammation is initiated by blood byproducts in the subarachnoid space and/or brain parenchyma. In both cases, neuroinflammation is characterized by the activation of resident immune cells, such as microglia and astrocytes, and infiltration of peripheral immune cells, leading to the release of pro-inflammatory cytokines, chemokines, and reactive oxygen species. These inflammatory mediators contribute to blood-brain barrier disruption, neuronal damage, and cerebral edema, promoting neuronal apoptosis and impairing neuroplasticity, ultimately exacerbating the neurologic deficit. However, neuroinflammation can also have beneficial effects by clearing cellular debris and promoting tissue repair. The role of neuroinflammation in AIS and ICH is complex and multifaceted, and further research is necessary to develop effective therapies that target this process. Intracerebral hemorrhage (ICH) will be the HS subtype addressed in this review. Neuroinflammation is a significant contributor to brain tissue damage following AIS and HS. Understanding the mechanisms and cellular players involved in neuroinflammation is essential for developing effective therapies to reduce secondary injury and improve stroke outcomes. Recent findings have provided new insights into the pathophysiology of neuroinflammation, highlighting the potential for targeting specific cytokines, chemokines, and glial cells as therapeutic strategies.

New role of astrocytes in neuroprotective mechanisms after ischemic stroke

Astrocytes are the most abundant cell subtypes in the central nervous system. Previous studies believed that astrocytes are supporting cells in the brain, which only provide nutrients for neurons. However, recent studies have found that astrocytes have more crucial and complex functions in the brain, such as neurogenesis, phagocytosis, and ischemic tolerance. After an ischemic stroke, the activated astrocytes can exert neuroprotective or neurotoxic effects through a variety of pathways. In this review, we will discuss the neuroprotective mechanisms of astrocytes in cerebral ischemia, and mainly focus on reactive astrocytosis or glial scar, neurogenesis, phagocytosis, and cerebral ischemic tolerance, for providing new strategies for the clinical treatment of stroke.

Microglia-Astrocyte Interaction in Neural Development and Neural Pathogenesis

The interaction between microglia and astrocytes exhibits a relatively balanced state in order to maintain homeostasis in the healthy central nervous system (CNS). Disease stimuli alter microglia-astrocyte interaction patterns and elicit cell-type-specific responses, resulting in their contribution to various pathological processes. Here, we review the similarities and differences in the activation modes between microglia and astrocytes in various scenarios, encompassing different stages of neural development and a wide range of neural disorders. The aim is to provide a comprehensive understanding of their roles in neural development and regeneration and guiding new strategies for restoring CNS homeostasis.

Proteomics identifies lipocalin-2 in neonatal inflammation associated with cerebrovascular alteration in mice and preterm infants

Staphylococcus (S.) epidermidis is the most common nosocomial coagulase-negative staphylococci infection in preterm infants. Clinical signs of infection are often unspecific and novel markers to complement diagnosis are needed. We investigated proteomic alterations in mouse brain after S. epidermidis infection and in preterm infant blood. We identified lipocalin-2 (LCN2) as a crucial protein associated with cerebrovascular changes and astrocyte reactivity in mice. We further proved that LCN2 protein expression was associated with endothelial cells but not astrocyte reactivity. By combining network analysis and differential expression approaches, we identified LCN2 linked to blood C-reactive protein levels in preterm infants born <28 weeks of gestation. Blood LCN2 levels were associated with similar alterations of cytokines and chemokines in both infected mice and human preterm infants with increased levels of C-reactive protein. This experimental and clinical study suggests that LCN2 may be a marker of preterm infection/inflammation associated with cerebrovascular changes and neuroinflammation.

Distinct brain morphometry patterns revealed by deep learning improve prediction of aphasia severity

Emerging evidence suggests that post-stroke aphasia severity depends on the integrity of the brain beyond the stroke lesion. While measures of lesion anatomy and brain integrity combine synergistically to explain aphasic symptoms, significant interindividual variability remains unaccounted for. A possible explanatory factor may be the spatial distribution of brain atrophy beyond the lesion. This includes not just the specific brain areas showing atrophy, but also distinct three-dimensional patterns of atrophy. Here, we tested whether deep learning with Convolutional Neural Networks (CNN) on whole brain morphometry (i.e., segmented tissue volumes) and lesion anatomy can better predict which individuals with chronic stroke (N=231) have severe aphasia, and whether encoding spatial dependencies in the data might be capable of improving predictions by identifying unique individualized spatial patterns. We observed that CNN achieves significantly higher accuracy and F1 scores than Support Vector Machine (SVM), even when the SVM is nonlinear or integrates linear and nonlinear dimensionality reduction techniques. Performance parity was only achieved when the SVM was directly trained on the latent features learned by the CNN. Saliency maps demonstrated that the CNN leveraged widely distributed patterns of brain atrophy predictive of aphasia severity, whereas the SVM focused almost exclusively on the area around the lesion. Ensemble clustering of CNN saliency maps revealed distinct morphometry patterns that were unrelated to lesion size, highly consistent across individuals, and implicated unique brain networks associated with different cognitive processes as measured by the wider neuroimaging literature. Individualized predictions of severity depended on both ipsilateral and contralateral features outside of the location of stroke. Our findings illustrate that three-dimensional network distributions of atrophy in individuals with aphasia are directly associated with aphasia severity, underscoring the potential for deep learning to improve prognostication of behavioral outcomes from neuroimaging data, and highlighting the prospective benefits of interrogating spatial dependence at different scales in multivariate feature space.

Gain-of-function of progesterone receptor membrane component 2 ameliorates ischemic brain injury

OBJECTIVE

Progesterone receptor membrane component 2 (PGRMC2) belongs to the membrane-associated progesterone receptor family, which regulates multiple pathophysiological processes. However, the role of PGRMC2 in ischemic stroke remains unexplored. The present study sought to determine the regulatory role of PGRMC2 in ischemic stroke.

METHODS

Male C57BL/6J mice were subjected to middle cerebral artery occlusion (MCAO). The protein expression level and localization of PGRMC2 were examined by western blotting and immunofluorescence staining. The gain-of-function ligand of PGRMC2 (CPAG-1, 45 mg/kg) was intraperitoneally injected into sham/MCAO mice, and brain infarction, blood-brain barrier (BBB) leakage, and sensorimotor functions were evaluated by magnetic resonance imaging, brain water content, Evans blue extravasation, immunofluorescence staining, and neurobehavioral tests. The astrocyte and microglial activation, neuronal functions, and gene expression profiles were revealed by RNA sequencing, qPCR, western blotting, and immunofluorescence staining after surgery and CPAG-1 treatment.

RESULTS

Progesterone receptor membrane component 2 was elevated in different brain cells after ischemic stroke. Intraperitoneal delivery of CPAG-1 reduced infarct size, brain edema, BBB leakage, astrocyte and microglial activation, and neuronal death, and improved sensorimotor deficits after ischemic stroke.

CONCLUSION

CPAG-1 acts as a novel neuroprotective compound that could reduce neuropathologic damage and improve functional recovery after ischemic stroke.

Targeting p53 for neuroinflammation: New therapeutic strategies in ischemic stroke

Ischemic stroke (IS) is characterized by high incidence, high recurrence, and high mortality and places a heavy burden on society and families. The pathological mechanisms of IS are complex, among which secondary neurological impairment mediated by neuroinflammation is considered to be the main factor in cerebral ischemic injury. At present, there is still a lack of specific therapies to treat neuroinflammation. The tumor suppressor protein p53 has long been regarded as a key substance in the regulation of the cell cycle and apoptosis in the past. Recently, studies have found that p53 also plays an important role in neuroinflammatory diseases, such as IS. Therefore, p53 may be a crucial target for the regulation of the neuroinflammatory response. Here, we provide a comprehensive review of the potential of targeting p53 in the treatment of neuroinflammation after IS. We describe the function of p53, the major immune cells involved in neuroinflammation, and the role of p53 in inflammatory responses mediated by these cells. Finally, we summarize the therapeutic strategies of targeting p53 in regulating the neuroinflammatory response after IS to provide new directions and ideas for the treatment of ischemic brain injury.

Rat BM-MSCs secretome alone and in combination with stiripentol and ISRIB, ameliorated microglial activation and apoptosis in experimental stroke

BACKGROUND

Stroke, a devastating neurological emergency, is the leading cause of worldwide mortality and functional disability. Combining novel neuroprotective drugs offers a way to improve the stroke intervention outcomes. In the present era, the combination therapy has been proposed as a plausible strategy to target multiple mechanisms and enhance the treatment efficacy to rescue stroke induced behavioral abnormalities and neuropathological damage. In the current study, we have investigated the neuroprotective effect of stiripentol (STP) and trans integrated stress response inhibitor (ISRIB) alone and in combination with rat bone marrow derived mesenchymal stem cells (BM-MSCs) secretome in an experimental model of stroke.

MATERIALS & METHODS

Stroke was induced in male Wistar rats (n=92) by temporary middle cerebral artery occlusion (MCAO). Three investigational agents were selected including STP (350mg/kg; i.p.), trans ISRIB (2.5mg/kg; i.p.) and rat BM-MSCs secretome (100µg/kg; i.v). Treatment was administered at 3 hrs post MCAO, in four doses with a 12 hrs interval. Post MCAO, neurological deficits, brain infarct, brain edema, BBB permeability, motor functional and memory deficits were assessed. Molecular parameters: oxidative stress, pro inflammatory cytokines, synaptic protein markers, apoptotic protein markers and histopathological damage were assessed.

RESULTS

STP and trans ISRIB, alone and in combination with rat BM-MSCs secretome, significantly improved neurological, motor function and memory deficits along with significant reduction in pyknotic neurons in the brain of post MCAO rats. These results were correlating with significant reduction in pro-inflammatory cytokines, microglial activation and apoptotic markers in the brain of drug treated post MCAO rats.

CONCLUSION

STP and trans ISRIB, alone and in combination with rat BM-MSCs secretome, might be considered as potential neuroprotective agents in the acute ischemic stroke (AIS) management.

DATA AVAILABILITY STATEMENT

Data will be made available on reasonable request.

APP96-110 Elicits Neuroprotective Effects Following Ischemic Insult in Animal Models

Competitive amyloidogenic pathways play an important role in many neurological diseases such as the onset of various degenerative diseases and ischemic stroke. Overexpression of amyloid precursor protein (APP) and amyloid-beta is modulated via the amyloidogenic pathway, which plays a crucial role in neuroinflammation. During ischemic conditions, the activity of the anti-inflammatory non-amyloidogenic pathway decreases, thus increasing the activity of amyloidogenic pathway. The soluble alpha form of APP (sAPPα), formed via the non-amyloidogenic pathway, exhibits neuroprotective effects against neurological diseases. sAPPα is thought to have a modulatory effect on several cell survival pathways, including its ability to inhibit the phosphoinositide 3-kinases (PI3K) pathway, thereby inhibiting the inflammatory response. The APP derivative, APP96-110, could act as a functional substitute for native sAPPα. Herein, we investigated whether APP96-110 has neuroprotective effects against neuroinflammation and damage following cerebral ischemic stroke. Treatment with diluted APP96-110 (0.005 mg/kg) in mice after 30 min of transient middle cerebral artery occlusion (tMCAO) showed improved motor function and reduced expression of the inflammatory marker CD86. APP96-110 decreased the infarct size and induced an anti-inflammatory response by inhibiting the PI3K pathway. These results suggest that the treatment of APP96-110 is efficacious in reducing neuroinflammation and infarct size in ischemic stroke.

Post-ischemic inflammatory response in the brain: Targeting immune cell in ischemic stroke therapy

An ischemic stroke occurs when the blood supply is obstructed to the vascular basin, causing the death of nerve cells and forming the ischemic core. Subsequently, the brain enters the stage of reconstruction and repair. The whole process includes cellular brain damage, inflammatory reaction, blood–brain barrier destruction, and nerve repair. During this process, the proportion and function of neurons, immune cells, glial cells, endothelial cells, and other cells change. Identifying potential differences in gene expression between cell types or heterogeneity between cells of the same type helps to understand the cellular changes that occur in the brain and the context of disease. The recent emergence of single-cell sequencing technology has promoted the exploration of single-cell diversity and the elucidation of the molecular mechanism of ischemic stroke, thus providing new ideas and directions for the diagnosis and clinical treatment of ischemic stroke.

Role of lipocalin 2 in stroke

Stroke is the second leading cause of death worldwide; however, the treatment choices available to neurologists are limited in clinical practice. Lipocalin 2 (LCN2) is a secreted protein, belonging to the lipocalin superfamily, with multiple biological functions in mediating innate immune response, inflammatory response, iron-homeostasis, cell migration and differentiation, energy metabolism, and other processes in the body. LCN2 is expressed at low levels in the brain under normal physiological conditions, but its expression is significantly up-regulated in multiple acute stimulations and chronic pathologies. An up-regulation of LCN2 has been found in the blood/cerebrospinal fluid of patients with ischemic/hemorrhagic stroke, and could serve as a potential biomarker for the prediction of the severity of acute stroke. LCN2 activates reactive astrocytes and microglia, promotes neutrophil infiltration, amplifies post-stroke inflammation, promotes blood-brain barrier disruption, white matter injury, and neuronal death. Moreover, LCN2 is involved in brain injury induced by thrombin and erythrocyte lysates, as well as microvascular thrombosis after hemorrhage. In this paper, we review the role of LCN2 in the pathological processes of ischemic stroke; intracerebral hemorrhage; subarachnoid hemorrhage; and stroke-related brain diseases, such as vascular dementia and post-stroke depression, and their underlying mechanisms. We hope that this review will help elucidate the value of LCN2 as a therapeutic target in stroke.

Molecular Hydrogen: an Emerging Therapeutic Medical Gas for Brain Disorders

Oxidative stress and neuroinflammation are the main physiopathological changes involved in the initiation and progression of various neurodegenerative disorders or brain injuries. Since the landmark finding reported in 2007 found that hydrogen reduced the levels of peroxynitrite anions and hydroxyl free radicals in ischemic stroke, molecular hydrogen's antioxidative and anti-inflammatory effects have aroused widespread interest. Due to its excellent antioxidant and anti-inflammatory properties, hydrogen therapy via different routes of administration exhibits great therapeutic potential for a wide range of brain disorders, including Alzheimer's disease, neonatal hypoxic-ischemic encephalopathy, depression, anxiety, traumatic brain injury, ischemic stroke, Parkinson's disease, and multiple sclerosis. This paper reviews the routes for hydrogen administration, the effects of hydrogen on the previously mentioned brain disorders, and the primary mechanism underlying hydrogen's neuroprotection. Finally, we discuss hydrogen therapy's remaining issues and challenges in brain disorders. We conclude that understanding the exact molecular target, finding novel routes, and determining the optimal dosage for hydrogen administration is critical for future studies and applications.

Non-genomic Effect of Estradiol on the Neurovascular Unit and Possible Involvement in the Cerebral Vascular Accident

Cerebrovascular diseases, such as ischemic cerebral vascular accident (CVA), are responsible for causing high rates of morbidity, mortality, and disability in the population. The neurovascular unit (NVU) during and after ischemic CVA plays crucial roles in cell regulation and preservation, the immune and inflammatory response, and cell and/or tissue survival and repair. Cellular responses to 17β-estradiol (E2) can be triggered by two mechanisms: one called classical or genomic, which is due to the activation of the "classical" nuclear estrogen receptors α (ERα) and β (ERβ), and the non-genomic or rapid mechanism, which is due to the activation of the G protein-coupled estrogen receptor 1 (GPER) that is located in the plasma membrane and some in intracellular membranes, such as in the Golgi apparatus and endoplasmic reticulum. Nuclear receptors can regulate gene expression and cellular functions. On the contrary, activating the GPER by E2 and/or its G-1 agonist triggers several rapid cell signaling pathways. Therefore, E2 or its G-1 agonist, by mediating GPER activation and/or expression, can influence several NVU cell types. Most studies argue that the activation of the GPER may be used as a potential therapeutic target in various pathologies, such as CVA. Thus, with this review, we aimed to summarize the existing literature on the role of GPER mediated by E2 and/or its agonist G-1 in the physiology and pathophysiology of NVU.

Astrocyte-neuron lactate shuttle plays a pivotal role in sensory-based neuroprotection in a rat model of permanent middle cerebral artery occlusion

We have previously demonstrated protection from impending cortical stroke is achievable by sensory stimulation of the ischemic area in an adult rat model of permanent middle cerebral artery occlusion (pMCAo). We have further demonstrated that a major underpinning mechanism that is necessary for such protection is the system of collaterals among cerebral arteries that results in reperfusion of the MCA ischemic territory. However, since such collateral flow is weak, it may be necessary but not sufficient for protection and therefore we were seeking other complementary mechanisms that contribute to sensory-based protection. We hypothesized that astrocytes-to-neuron shuttle (ANLS) is another potential underpinning mechanism that could complement collateral flow in the protection process. Supporting our hypothesis, using functional imaging, pharmacological treatments, and postmortem histology, we show that ANLS has a pivotal role in sensory-based protection of cortex and therefor serves as the other supporting mechanism underpinning the protection process.

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

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

Reactive Oxygen Species-Responsive Transformable and Triple-Targeting Butylphthalide Nanotherapy for Precision Treatment of Ischemic Stroke by Normalizing the Pathological Microenvironment

High potency and safe therapies are still required for ischemic stroke, which is a leading cause of global death and disability. Herein, a reactive oxygen species (ROS)-responsive, transformable, and triple-targeting dl-3-n-butylphthalide (NBP) nanotherapy was developed for ischemic stroke. To this end, a ROS-responsive nanovehicle (OCN) was first constructed using a cyclodextrin-derived material, which showed considerably enhanced cellular uptake in brain endothelial cells due to notably reduced particle size, morphological transformation, and surface chemistry switching upon triggering via pathological signals. Compared to a nonresponsive nanovehicle, this ROS-responsive and transformable nanoplatform OCN exhibited a significantly higher brain accumulation in a mouse model of ischemic stroke, thereby affording notably potentiated therapeutic effects for the nanotherapy derived from NBP-containing OCN. For OCN decorated with a stroke-homing peptide (SHp), we found significantly increased transferrin receptor-mediated endocytosis, in addition to the previously recognized targeting capability to activated neurons. Consistently, the engineered transformable and triple-targeting nanoplatform, i.e., SHp-decorated OCN (SON), displayed a more efficient distribution in the injured brain in mice with ischemic stroke, showing considerable localization in endothelial cells and neurons. Furthermore, the finally formulated ROS-responsive transformable and triple-targeting nanotherapy (NBP-loaded SON) demonstrated highly potent neuroprotective activity in mice, which outperformed the SHp-deficient nanotherapy at a 5-fold higher dose. Mechanistically, our bioresponsive, transformable, and triple-targeting nanotherapy attenuated the ischemia/reperfusion-induced endothelial permeability and improved dendritic remodeling and synaptic plasticity of neurons in the injured brain tissue, thereby promoting much better functional recovery, which were achieved by efficiently enhancing NBP delivery to the ischemic brain tissue, targeting injured endothelial cells and activated neurons/microglial cells, and normalizing the pathological microenvironment. Moreover, preliminary studies indicated that the ROS-responsive NBP nanotherapy displayed a good safety profile. Consequently, the developed triple-targeting NBP nanotherapy with desirable targeting efficiency, spatiotemporally controlled drug release performance, and high translational potential holds great promise for precision therapy of ischemic stroke and other brain diseases.

S100B Expression Plays a Crucial Role in Cytotoxicity, Reactive Oxygen Species Generation and Nitric Oxide Synthase Activation Induced by Amyloid β-Protein in an Astrocytoma Cell Line

S100B is an astrocytic cytokine that has been shown to be involved in several neurodegenerative diseases. We used an astrocytoma cell line (U373 MG) silenced for S100B, and stimulated it with amyloid beta-peptide (Aβ) as a known paradigm factor for astrocyte activation, and showed that the ability of the cell (including the gene machinery) to express S100B is a prerequisite for inducing reactive astrocytic features, such as ROS generation, NOS activation and cytotoxicity. Our results showed that control astrocytoma cell line exhibited overexpression of S100B after Aβ treatment, and subsequently cytotoxicity, increased ROS generation and NOS activation. In contrast, cells silenced with S100B were essentially protected, consistently reducing cell death, significantly decreasing oxygen radical generation and nitric oxide synthase activity. The conclusive aim of the present study was to show a causative linkage between the cell expression of S100B and induction of astrocyte activation processes, such as cytotoxicity, ROS and NOS activation.