Endothelial S1P 1 Signaling Counteracts Infarct Expansion in Ischemic Stroke

Rationale: Cerebrovascular function is critical for brain health, and endogenous vascular-protective pathways may provide therapeutic targets for neurological disorders. Sphingosine 1-phosphate (S1P) signaling coordinates vascular functions in other organs, and S1P receptor-1 (S1P 1 ) modulators including fingolimod show promise for the treatment of ischemic and hemorrhagic stroke. However, S1P 1 also coordinates lymphocyte trafficking, and lymphocytes are currently viewed as the principal therapeutic target for S1P 1 modulation in stroke. Objective: To address roles and mechanisms of engagement of endothelial cell (EC) S1P 1 in the naïve and ischemic brain and its potential as a target for cerebrovascular therapy. Methods and Results: Using spatial modulation of S1P provision and signaling, we demonstrate a critical vascular protective role for endothelial S1P 1 in the mouse brain. With an S1P 1 signaling reporter, we reveal that abluminal polarization shields S1P 1 from circulating endogenous and synthetic ligands after maturation of the blood-neural barrier, restricting homeostatic signaling to a subset of arteriolar ECs. S1P 1 signaling sustains hallmark endothelial functions in the naïve brain, and expands during ischemia by engagement of cell-autonomous S1P provision. Disrupting this pathway by EC-selective deficiency in S1P production, export, or the S1P 1 receptor substantially exacerbates brain injury in permanent and transient models of ischemic stroke. By contrast, profound lymphopenia induced by loss of lymphocyte S1P 1 provides modest protection only in the context of reperfusion. In the ischemic brain, EC S1P 1 supports blood-brain barrier (BBB) function, microvascular patency, and the rerouting of blood to hypo-perfused brain tissue through collateral anastomoses. Selective S1P 1 agonism counteracts cortical infarct expansion after middle cerebral artery occlusion by engaging the endothelial receptor pool after BBB penetration. Conclusions: This study provides genetic evidence to support a pivotal role for the endothelium in maintaining perfusion and microvascular patency in the ischemic penumbra that is coordinated by S1P signaling and can be harnessed for neuroprotection with BBB-penetrating S1P 1 agonists.

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Abstract WP134: 3K3A-APC Protects Pericyte-deficient Mice From Ischemic Brain Injury

Stroke ◽

10.1161/str.51.suppl_1.wp134 ◽

2020 ◽

Vol 51 (Suppl_1) ◽

Author(s):

Yaoming Wang ◽

Mikko Huuskonen ◽

Axel Montagne ◽

Berislav Zlokovic

Keyword(s):

Ischemic Stroke ◽

Brain Injury ◽

Activated Protein C ◽

Artery Occlusion ◽

Ischemic Brain Injury ◽

Neuroprotective Effects ◽

Ischemic Brain ◽

Functional Deficits ◽

Favorable Safety ◽

Cerebral Artery Occlusion

Pericytes play a key role in maintaining the blood-brain barrier (BBB) integrity. BBB disruption occurs during early stages after ischemic stroke. However, the role of pericytes in the pathogenesis of ischemic stroke remains still understudied. 3K3A-APC, a recombinant variant of activated protein C, has shown benefits in preclinical models of ischemic stroke and has favorable safety profile and reduces hemorrhage in Phase 2 study in ischemic stroke patients (RHAPSODY). In the present study, we used PDGFRβ heterozygous knockout (PDGFRβ+/-) mice to investigate the effects of pericyte deficiency on ischemic brain injury using transient proximal middle cerebral artery occlusion (tMCAO). Additionally, we investigated the effects of 3K3A-APC therapy (0.2mg/kg i.v. 4h after stroke) in this model. Compared to controls, pericyte deficiency in PDGFRβ+/- mice resulted in ~35% increase in the infarct and edema volumes, reduction in pericyte coverage from 58% to 25%, and increased IgG and fibrin deposition suggesting accelerated BBB breakdown 24h after stroke. Additionally, PDGFRβ+/- mice showed by 36% more degenerating Fluoro-Jade+ neurons and exhibited accelerated neurobehavioral abnormalities. 3K3A-APC improved neuropathological changes and functional deficits. Our results suggest that pericyte deficiency worsens brain damage and functional outcome after ischemic stroke in mice suggesting that pericytes may play an important role in protecting brain from post-ischemic. We also suggests that 3K3A-APC protects pericyte function in stroked mice which could contribute to its overall neuroprotective effects.

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Sphingosine 1-phosphate, a Novel TREM2 Ligand, Promotes Phagocytosis and Reduce Ischemic Injury

10.21203/rs.3.rs-114600/v1 ◽

2020 ◽

Author(s):

Xiu-Lan Sun ◽

Teng-Fei Xue ◽

Juan Ji ◽

Ruo-Bing Guo ◽

Yu-Qin Sun ◽

...

Keyword(s):

Ischemic Stroke ◽

Infarct Volume ◽

Glucose Deprivation ◽

Artery Occlusion ◽

Endogenous Ligand ◽

Microglial Phagocytosis ◽

Neurological Score ◽

Cellular Debris ◽

Sphingosine 1 Phosphate ◽

Cerebral Artery Occlusion

Abstract Background: Activation of TREM2 protects against brain injury in ischemic stroke via immunoregulation. However, the endogenous ligand of TREM2 remains unknown. Here, we tested the hypothesis that S1P, an immunoregulator, functions as TREM2 ligand to promote microglial phagocytosis.Methods: SD rats, C57BL/6J mice and TREM2-/- mice were subjected to transient middle cerebral artery occlusion, and primary microglia were subjected to oxygen-glucose deprivation. Phagocytosis was investigated via immunofluorescence and two-photon microscope. LC-MS/MS, microscale thermophoresis and surface plasmon resonance were used to confirm the TREM2-S1P interaction.Results: FTY720, an analog of S1P, promoted microglial phagocytosis in ischemic stroke independent of S1PRs expressed on microglia. S1P was confirmed to be a novel endogenous ligand for TREM2 and promote cellular debris clearance. The enhanced cellular debris clearance ameliorated neurological score and infarct volume, relying on TREM2. Moreover, FTY720 was demonstrated to promote hemoglobin clearance in intracerebral hemorrhage and ameliorate hemorrhagic injury.Conlusions: The present work reveals for the first time that S1P acts as a novel endogenous ligand of TREM2 to effectively promote microglial phagocytosis, and provides a new lead compound for developing TREM2 modulator.

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A Sphingosine 1-Phosphate Gradient Is Linked to the Cerebral Recruitment of T Helper and Regulatory T Helper Cells during Acute Ischemic Stroke

International Journal of Molecular Sciences ◽

10.3390/ijms21176242 ◽

2020 ◽

Vol 21 (17) ◽

pp. 6242

Author(s):

Alexandra Lucaciu ◽

Hannah Kuhn ◽

Sandra Trautmann ◽

Nerea Ferreirós ◽

Helmuth Steinmetz ◽

...

Keyword(s):

Ischemic Stroke ◽

Expression Patterns ◽

Treg Cells ◽

Artery Occlusion ◽

T Helper ◽

Sphingosine 1 Phosphate ◽

Cerebral Artery Occlusion ◽

Kinetics Of ◽

The Brain

Emerging evidence suggests a complex relationship between sphingosine 1-phosphate (S1P) signaling and stroke. Here, we show the kinetics of S1P in the acute phase of ischemic stroke and highlight accompanying changes in immune cells and S1P receptors (S1PR). Using a C57BL/6 mouse model of middle cerebral artery occlusion (MCAO), we assessed S1P concentrations in the brain, plasma, and spleen. We found a steep S1P gradient from the spleen towards the brain. Results obtained by qPCR suggested that cells expressing the S1PR type 1 (S1P1+) were the predominant population deserting the spleen. Here, we report the cerebral recruitment of T helper (TH) and regulatory T (TREG) cells to the ipsilateral hemisphere, which was associated with differential regulation of cerebral S1PR expression patterns in the brain after MCAO. This study provides insight that the S1P-S1PR axis facilitates splenic T cell egress and is linked to the cerebral recruitment of S1PR+ TH and TREG cells. Further insights by which means the S1P-S1PR-axis orchestrates neuronal positioning may offer new therapeutic perspectives after ischemic stroke.

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Silencing of lncRNA XLOC_035088 Protects Middle Cerebral Artery Occlusion-Induced Ischemic Stroke by Notch1 Signaling

Journal of Neuropathology & Experimental Neurology ◽

10.1093/jnen/nlaa129 ◽

2020 ◽

Vol 80 (1) ◽

pp. 60-70

Author(s):

Miao Chen ◽

Feng Wang ◽

Hairong Wang

Keyword(s):

Ischemic Stroke ◽

Brain Injury ◽

Middle Cerebral Artery ◽

Middle Cerebral Artery Occlusion ◽

Cerebral Artery ◽

Hippocampal Neurons ◽

Artery Occlusion ◽

Ischemic Brain Injury ◽

Ischemic Brain ◽

Cerebral Artery Occlusion

Abstract Ischemic stroke represents one of the leading causes of mortality worldwide and especially in developing countries. It is crucial for finding effective therapeutic targets that protect the brain against ischemic injury. Long noncoding RNAs (lncRNAs) have emerged as major regulators of neurological diseases, and clarifying their roles in cerebral ischemic injury may provide novel targets for the treatment of ischemic stroke. We aimed to investigate the role of lncRNA-XLOC_035088 in middle cerebral artery occlusion (MCAO)-induced rat brain injury and oxygen-glucose deprivation (OGD)-reperfusion treated hippocampal neurons. In our findings, we found that XLOC_035088 expression was significantly upregulated in OGD-reperfusion treated hippocampal neurons and in different brain regions of MCAO-treated rats. XLOC_035088 silencing protected against MCAO-induced ischemic brain injury in vivo and OGD-induced hippocampal neuronal apoptosis in vitro. Intrahippocampal silencing of XLOC_035088 significantly decreased brain XLOC_035088 expression, reduced brain infarct size, and improved neurological function through inhibiting NOTCH1 following derepression of presenilin 2 (PSEN2). Taken together, this study provides evidence that the lncRNA XLOC_035088/PSEN2/Notch1 axis is involved in the pathogenesis of ischemic brain injury, and presents a promising therapeutic route for ischemic stroke.

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Long Course Hyperbaric Oxygen Stimulates Neurogenesis and Attenuates Inflammation after Ischemic Stroke

Mediators of Inflammation ◽

10.1155/2013/512978 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 27

Author(s):

Ying-Sheng Lee ◽

Chung-Ching Chio ◽

Ching-Ping Chang ◽

Liang-Chao Wang ◽

Po-Min Chiang ◽

...

Keyword(s):

Ischemic Stroke ◽

Hyperbaric Oxygen ◽

Artery Occlusion ◽

Trophic Factors ◽

Therapeutic Effects ◽

Ischemic Brain ◽

Neurological Severity Score ◽

Group Mobilization ◽

Long Course ◽

Cerebral Artery Occlusion

Several studies have provided evidence with regard to the neuroprotection benefits of hyperbaric oxygen (HBO) therapy in cases of stroke, and HBO also promotes bone marrow stem cells (BMSCs) proliferation and mobilization. This study investigates the influence of HBO therapy on the migration of BMSCs, neurogenesis, gliosis, and inflammation after stroke. Rats that sustained transient middle cerebral artery occlusion (MCAO) were treated with HBO three weeks or two days. The results were examined using a behavior test (modified neurological severity score, mNSS) and immunostaining to evaluate the effects of HBO therapy on migration of BMSCs, neurogenesis, and gliosis, and expression of neurotrophic factors was also evaluated. There was a lower mNSS score in the three-week HBO group when compared with the two-day HBO group. Mobilization of BMSCs to an ischemic area was more improved in long course HBO treatments, suggesting the duration of therapy is crucial for promoting the homing of BMSCs to ischemic brain by HBO therapies. HBO also can stimulate expression of trophic factors and improve neurogenesis and gliosis. These effects may help in neuronal repair after ischemic stroke, and increasing the course of HBO therapy might enhance therapeutic effects on ischemic stroke.

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Hyperglycemia primes NETosis, which exacerbates ischemic brain damage

10.21203/rs.2.18044/v1 ◽

2019 ◽

Author(s):

Jiangshan Deng ◽

Fei Zhao ◽

Yunlong Zhang ◽

Yajun Zhou ◽

Xiaofeng Xu ◽

...

Keyword(s):

Ischemic Stroke ◽

Middle Cerebral Artery ◽

Brain Damage ◽

Artery Occlusion ◽

Wild Type ◽

Stroke Patients ◽

Acute Hyperglycemia ◽

Ischemic Brain ◽

Infarction Volume ◽

Cerebral Artery Occlusion

Abstract Background：Hyperglycemia is common and associated with poor outcomes in acute ischemic stroke patients. It is not well understood how hyperglycemia exacerbates brain damage in ischemic stroke. Neutrophil extracellular traps (NETs) have shown an emerging role in noninfectious diseases. We aimed to determine the role of NETs in acute ischemic stroke with hyperglycemia. Methods: NETs were immunostained using NET markers (citrullinated histone H3 (H3Cit)) and quantified in thrombi retrieved from ischemic stroke patients undergoing endovascular treatment. BKS-db/db and wild-type mice were used to establish the permanent middle cerebral artery occlusion (pMCAO) model. Wild-type mice were injected with glucose to simulate acute hyperglycemia after middle cerebral artery occlusion. NETs were detected in the peri-ischemic brain tissue. After inhibition of NET formation, infarction volume, neurological function and inflammatory factors in pMCAO mice were evaluated. Results: H3Cit, a marker of NETs, was observed in almost all thrombi. H3Cit was much more abundant in thrombi from diagnosed diabetic patients and acute hyperglycemic patients compared with those in normglycemic patients. In pMCAO mice, NETs were induced by chronic diabetes and acute hyperglycemia. Inhibition of NET formation with the peptidylarginine deiminase 4 (PAD4) inhibitor Cl-amidine decreased the infarction volume both in db/db and wild-type mice with hyperglycemia. Neurological function deficits were alleviated by blocking NET formation, as shown in the grip strength and rotarod tests. The levels of TNF-α and IL-1β but not IL-6 coincided with NET formation. Conclusions: Hyperglycemia may exacerbate brain damage in ischemic stroke through NETs. The underlying mechanisms deserve to be further studied.

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A Microarray Study of Middle Cerebral Occlusion Rat Brain with Acupuncture Intervention

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2015/496932 ◽

2015 ◽

Vol 2015 ◽

pp. 1-13 ◽

Cited By ~ 2

Author(s):

Chao Zhang ◽

Yan Wen ◽

Xiaonong Fan ◽

Sha Yang ◽

Guang Tian ◽

...

Keyword(s):

Ischemic Stroke ◽

Rat Brain ◽

Microarray Analysis ◽

Quantitative Polymerase Chain Reaction ◽

Artery Occlusion ◽

Pathological Process ◽

Ischemic Brain ◽

Acupuncture Intervention ◽

Polymerase Chain ◽

Cerebral Artery Occlusion

Microarray analysis was used to investigate the changes of gene expression of ischemic stroke and acupuncture intervention in middle cerebral artery occlusion (MCAo) rat brain. Results showed that acupuncture intervention had a remarkable improvement in neural deficit score, cerebral blood flow, and cerebral infarction volume of MCAo rats. Microarray analysis showed that a total of 627 different expression genes were regulated in ischemic stroke. 417 genes were upregulated and 210 genes were downregulated. A total of 361 different expression genes were regulated after acupuncture intervention. Three genes were upregulated and 358 genes were downregulated. The expression of novel genes after acupuncture intervention, includingTph1andOlr883, was further analyzed by Real-Time Quantitative Polymerase Chain Reaction (RT-PCR). Upregulation ofTph1and downregulation ofOlr883indicated that the therapeutic effect of acupuncture for ischemic stroke may be closely related to the suppression of poststroke depression and regulation of olfactory transduction. In conclusion, the present study may enrich our understanding of the multiple pathological process of ischemic brain injury and indicate possible mechanisms of acupuncture on ischemic stroke.

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Antineuroinflammatory effects of dl-3-n-butylphthalide conferred by stimulation of Foxp3 and Ki-67 in an ischemic stroke model

10.21203/rs.3.rs-22724/v1 ◽

2020 ◽

Author(s):

Xi Liu ◽

Runzhe Liu ◽

Dongxu Fu ◽

Hao Wu ◽

Xin Zhao ◽

...

Keyword(s):

Ischemic Stroke ◽

Artery Occlusion ◽

Neurological Deficits ◽

Stroke Model ◽

Ki 67 ◽

Ischemic Brain ◽

Caspase 1 ◽

And Function ◽

Cerebral Artery Occlusion ◽

First Time

Abstract Background Dl-3-n-butylphthalide (NBP) has been widely used for the treatment of ischemic stroke in China. However, its mechanisms of action have not been fully elucidated. Methods We established a permanent middle cerebral artery occlusion (pMCAO) rat model and administered 4 mg/kg/d NBP by tail vein injection for 9 days. Changes in some molecules related to neuroinflammation, neovascularization and nerve regeneration were observed, such as MALDI-TOF MSI to study the distribution of phospholipids in the brain, LA-ICP MSI to observe the changes of Foxp3, Ki-67 and pCREB, immunohistochemistry to investigate NLRP3 and its downstream inflammatory products Caspase-1 and IL-1β. Results These results showed that NBP attenuated ischemic damage in pMCAO rats, accompanied by improving neurological deficits. It was revealed for the first time in an animal stroke model that NBP decreased the levels of PE (18:0), NLRP3, Caspase-1 and IL-1β, while increasing the levels of several phospholipids, such as PA (16:0/18:1), PA (18:0/22:6), PE (16:0/22:6), PE (P-18:0/22:6), PE (18:0/22:6), PS (18:0/22:6), PI (18:0/20:4), Foxp3, Ki-67 and pCREB, in the ischemic brain region. Conclusion These results provide evidence that NBP can reduce neuroinflammation in brain tissue and promote the regeneration of nerves and blood vessels, thus exerting a protective effect on neuromorphology and function.

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Modulation of Astrocytic Activation by Arundic Acid (ONO-2506) Mitigates Detrimental Effects of the Apolipoprotein E4 Isoform after Permanent Focal Ischemia in Apolipoprotein E Knock-in Mice

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/sj.jcbfm.9600063 ◽

2005 ◽

Vol 25 (6) ◽

pp. 748-762 ◽

Cited By ~ 15

Author(s):

Takashi Mori ◽

Terrence Town ◽

Jun Tan ◽

Narito Tateishi ◽

Takao Asano

Keyword(s):

Brain Damage ◽

Infarct Volume ◽

Artery Occlusion ◽

Ischemic Brain ◽

Human Apolipoprotein ◽

Beneficial Effects ◽

Neurologic Deficits ◽

Significant Amelioration ◽

Infarct Expansion ◽

Cerebral Artery Occlusion

Using homozygous human apolipoprotein E2 (apoE2) (2/2)-, apoE3 (3/3)-, or apoE4 (4/4)-knock-in (KI) mice, we have shown that delayed infarct expansion and reactive astrocytosis after permanent middle cerebral artery occlusion (pMCAO) were markedly exacerbated in 4/4-KI mice as compared with 2/2- or 3/3-KI mice. Here, we probed the putative causal relationship between enhanced astrocytic activation and exacerbation of brain damage in 4/4-KI mice using arundic acid (ONO-2506, Ono Pharmaceutical Co. Ltd), which is known to oppose astrocytic activation through its inhibitory action on S100B synthesis. In all of the KI mice, administration of arundic acid (10 mg/kg day, intraperitoneal, started immediately after pMCAO) induced significant amelioration of brain damage at 5 days after pMCAO in terms of infarct volumes (results expressed as the mean infarct volume (mm3) ±1s.d. in 2/2-, 3/3-, or 4/4-KI mice in the vehicle groups: 16±2, 15±2, or 22±2; in the arundic acid groups: 11±2 ( P<0.001), 11±2 ( P<0.001), or 12±2 ( P<0.001), as compared with the vehicle groups), neurologic deficits, and S100/glial fibrillary acidic protein burden in the peri-infarct area. The beneficial effects of arundic acid were most pronounced in 4/4-KI mice, wherein delayed infarct expansion together with deterioration of neurologic deficits was almost completely mitigated. The above results support the notion that the apoE4 isoform exacerbates brain damage during the subacute phase of pMCAO through augmentation of astrocytic activation. Thus, pharmacological modulation of astrocytic activation may confer a novel therapeutic strategy for ischemic brain damage, particularly in APOE ɛ4 carriers.

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Energy-Sensing Pathways in Ischemia: The Counterbalance Between AMPK and mTORC

Current Pharmaceutical Design ◽

10.2174/1381612825666191210152156 ◽

2020 ◽

Vol 25 (45) ◽

pp. 4763-4770

Author(s):

Angel Cespedes ◽

Mario Villa ◽

Irene Benito-Cuesta ◽

Maria J. Perez-Alvarez ◽

Lara Ordoñez ◽

...

Keyword(s):

Blood Flow ◽

Ischemic Stroke ◽

Middle Cerebral Artery ◽

Cause Of Death ◽

Artery Occlusion ◽

Brain Pathology ◽

Common Cause ◽

Specific Analysis ◽

Energy Sensing ◽

Cerebral Artery Occlusion

: Stroke is an important cause of death and disability, and it is the second leading cause of death worldwide. In humans, middle cerebral artery occlusion (MCAO) is the most common cause of ischemic stroke. The damage occurs due to the lack of nutrients and oxygen contributed by the blood flow. : The present review aims to analyze to what extent the lack of each of the elements of the system leads to damage and which mechanisms are unaffected by this deficiency. We believe that the specific analysis of the effect of lack of each component could lead to the emergence of new therapeutic targets for this important brain pathology.

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