Model Of Focal Cerebral Ischemia Research Articles

Melatonin Enhances the Therapeutic Effect of Plasma Exosomes Against Cerebral Ischemia-Induced Pyroptosis Through the TLR4/NF-κB Pathway

IntroductionIschemic stroke-induced inflammation and inflammasome-dependent pyroptotic neural death cause serious neurological injury. Nano-sized plasma exosomes have exhibited therapeutic potential against ischemia and reperfusion injury by ameliorating inflammation. To enhance its therapeutic potential in patients with ischemic injury, we isolated exosomes from melatonin-treated rat plasma and assessed the neurological protective effect in a rat model of focal cerebral ischemia.MethodsBasal plasma exosomes and melatonin-treated plasma exosomes were isolated and intravenously injected into a rat model of focal cerebral ischemia. Neurological recovery was evaluated by determining the modified neurological severity score (mNSS), infarct volume, and brain water content. Pyroptosis in the ischemic cortex was detected through dUTP nick-end labeling (TUNEL) assay, lactate dehydrogenase (LDH) release, and gasdermin D (GSDMD) cleavage. NLRP3 inflammasome assembly and global inflammatory cytokine secretion were detected by enzyme-linked immunosorbent assay (ELISA) and Western blot assay. In immunized Sprague–Dawley rats, microglia pyroptosis was determined through a positive percentage of IBA1+ and caspase-1 (p20)+ cells. Finally, the microRNA (miRNA) profiles in melatonin-treated plasma exosomes were analyzed by exosome miRNA microarray analysis.ResultsMelatonin treatment enhanced plasma exosome therapeutic effects against ischemia-induced inflammatory responses and inflammasome-mediated pyroptosis. In addition, we confirmed that ischemic stroke-induced pyroptotic cell death occurred in the microglia and neuron, while the administration of melatonin-treated exosomes further effectively decreased the infarct volume and improved recovery of function via regulation of the TLR4/NF-κB signaling pathway. Finally, the altered miRNA profiles in the melatonin-treated plasma exosomes demonstrated the regulatory mechanisms involved in neurological recovery after ischemic injury.ConclusionThis study suggests that nano-sized plasma exosomes with melatonin pretreatment might be a more effective strategy for patients with ischemic brain injury. Further exploration of key molecules in the plasma exosome may provide increased therapeutic value for cerebral ischemic injury.

Neuroprotective Effects of a Novel Inhibitor of c-Jun N-Terminal Kinase in the Rat Model of Transient Focal Cerebral Ischemia.

A novel specific inhibitor of c-Jun N-terminal kinase, 11H-indeno[1,2-b]quinoxalin-11-one oxime sodium salt (IQ-1S), has a high affinity to JNK3 compared to JNK1/JNK2. The aim of this work was to study the mechanisms of neuroprotective activity of IQ-1S in the models of reversible focal cerebral ischemia (FCI) in Wistar rats. The animals were administered with an intraperitoneal injection of IQ-1S (5 and 25 mg/kg) or citicoline (500 mg/kg). Administration of IQ-1S exerted a pronounced dose-dependent neuroprotective effect, not inferior to the effects of citicoline. Administration of IQ-1S at doses of 5 and 25 mg/kg reduced the infarct size by 20% and 50%, respectively, 48 h after FCI, whereas administration of citicoline reduced the infarct size by 34%. The administration of IQ-1S was associated with a faster amelioration of neurological status. Control rats showed a 2.0-fold increase in phospho-c-Jun levels in the hippocampus compared to the corresponding values in sham-operated rats 4 h after FCI. Administration of IQ-1S at a dose of 25 mg/kg reduced JNK-dependent phosphorylation of c-Jun by 20%. Our findings suggest that IQ-1S inhibits JNK enzymatic activity in the hippocampus and protects against stroke injury when administered in the therapeutic and prophylactic regimen in the rat model of FCI.

Brain Factor-7\xae improves learning and memory deficits and attenuates ischemic brain damage by reduction of ROS generation in stroke in vivo and in vitro

Brain Factor-7® (BF-7), silk fibroin peptide, is known to be effective in improvement of memory and learning ability. In this study, the effects of BF-7 (10 mg/kg, p.o., pre-treatment for 7 days and post-treatment for 7 days) on neuroprotection and memory and learning functions were investigated in a rat model of transient focal cerebral ischemia and a gerbil model of transient global forebrain ischemia. Furthermore, to find the mechanism of BF-7, we examined the neuroprotective and antioxidative effects of BF-7 in vitro using neuroblastoma (SH-SY5Y) cells. In vivo model, treatment with BF-7 significantly reduced the number of errors in 8-arm maze test and significantly increased latency time in passive avoidance test at 7 days after focal ischemia compared to those in the vehicle-treated group. In addition, treatment with BF-7 significantly decreased the infarct size or neuronal death at 7 day following transient ischemia compared to that in the vehicle-treated group. In vitro model, 10 or 20 μg/ml of BF-7 treatment significantly increased cell viability in dose-dependent manner. In addition, oxidative stress was significantly attenuated in the ischemic cells, showing that 10 or 20 μg/ml of BF-7 treatment significantly reduced the generation of reactive oxygen species (ROS) compared to that in the ischemic cells. These results indicate that BF-7 treatment can attenuate ischemic damages and improve memory deficits via reduction of ROS generation.

Electro-Acupuncture Promotes the Differentiation of Endogenous Neural Stem Cells via Exosomal microRNA 146b After Ischemic Stroke.

Background: Evidences indicate that exosomes-mediated delivery of microRNAs (miRNAs or miRs) is involved in the neurogenesis of stroke. This study was to investigate the role of exosomal miRNAs in non-drug therapy of electro-acupuncture (EA) regulating endogenous neural stem cells for stroke recovery.Methods: The model of focal cerebral ischemia and reperfusion in rats were established by middle cerebral artery occlusion (MCAO) and treated by EA. The exosomes were extracted from peri-ischemic striatum and identified by exosomal biomarkers, and detected differentially expressed miRNAs with microarray chip. Primary stem cells were cultured, and oxygen–glucose deprivation and reperfusion (OGD/R) was used to mimic vitro ischemic injury.Results: The levels of exosomal biomarkers TSG101 and CD81 were increased in peri-ischemic striatum after EA treatment, and we revealed 25 differentially expressed miRNAs in isolated exosomes, of which miR-146b was selected for further analysis, and demonstrated that EA increased miR-146b expression and its inhibitors could block the effects. Subsequently, we confirmed that EA upregulated miR-146b expression to promote neural stem cells differentiation into neurons in peri-ischemic striatum. In vitro, it was verified that OGD/R hindered neural stem cells differentiation, and miR-146b inhibitors furtherly suppressed its differentiation, simultaneously NeuroD1 was involved in neural stem cells differentiation into neurons. Moreover, in vivo we found EA promoted NeuroD1-mediated neural stem cells differentiation via miR-146b. In addition, EA also could improve neurological deficits through miR-146b after ischemic stroke.Conclusion: EA promotes the differentiation of endogenous neural stem cells via exosomal miR-146b to improve neurological injury after ischemic stroke.

Ethyl Pyruvate Increases Post-Ischemic Levels of Mitochondrial Energy Metabolites: A 13C-Labeled Cerebral Microdialysis Study.

Mitochondrial dysfunction after transient cerebral ischemia can be monitored by cerebral microdialysis (CMD) using changes in the lactate and pyruvate concentrations and ratio. Other metabolites associated with mitochondrial (dys)function are, e.g., tricyclic acid (TCA) and purine metabolites. Ethyl pyruvate (EP) is a putative neuroprotectant, supposedly targeting mitochondrial energy metabolism, but its effect on cerebral energy metabolism has never been described using microdialysis. In this study we monitored the metabolic effects of EP in the endothelin-1 (ET-1) rat model using perfusion with 13C-succinate and analysis of endogenous and 13C-labeled metabolites in the dialysates by liquid chromatography-mass spectrometry (LC-MS). Adult Sprague Dawley rats (n = 27 of which n = 11 were included in the study) were subjected to the microdialysis experiments. Microdialysis probes were perfused with 13C-labeled succinate (1 mM), and striatal dialysates were collected at 30 min intervals before induction of the insult, during intracerebral application of ET-1, and during intravenous treatment with either EP (40 mg/kg) or placebo, which was administered immediately after the insult. The rats were subjected to transient cerebral ischemia by unilateral microinjection of ET-1 in the piriform cortex, causing vasoconstriction of the medial cerebral artery. Monitoring was continued for 5 h after reperfusion, and levels of endogenous and 13C-labeled energy metabolites before and after ischemia-reperfusion were compared in EP-treated and control groups. Infarct volumes were assessed after 24 h. In both the EP-treated and placebo groups, ET-1-induced vasoconstriction resulted in a transient depression of interstitial glucose and elevation of lactate in the ipsilateral striatum. In the reperfusion phase, the concentrations of labeled malate, isocitrate, and lactate as well as endogenous xanthine were significantly higher in the EP-group than in the placebo-group: (mean ± SEM) labeled malate: 39.5% ± 14.9, p = 0.008; labeled isocitrate: 134.8% ± 67.9, p = 0.047; labeled lactate: 61% ± 22.0, p = 0.007; and endogenous xanthine: 93.9% ± 28.3, p = 0.0009. In the placebo group, significantly elevated levels of uridine were observed (mean ± SEM) 32.5% ± 12.7, p = 0.01. Infarct volumes were not significantly different between EP-treated and placebo groups, p = 0.4679. CMD labeled with 13C-succinate enabled detection of ischemic induction and EP treatment effects in the ET-1 rat model of transient focal cerebral ischemia. EP administered as a single intravenous bolus in the reperfusion-phase after transient cerebral ischemia increased de novo synthesis of several key intermediate energy metabolites (13C-malate, 13C-isocitrate, and endogenous xanthine). In summary, mitochondria process 13C-succinate more effectively after EP treatment.

Inhibition of eIF5A hypusination pathway as a new pharmacological target for stroke therapy

In eukaryotes, the polyamine pathway generates spermidine that activates the hypusination of the translation factor eukaryotic initiation factor 5A (eIF5A). Hypusinated-eIF5A modulates translation, elongation, termination and mitochondrial function. Evidence in model organisms like drosophila suggests that targeting polyamines synthesis might be of interest against ischemia. However, the potential of targeting eIF5A hypusination in stroke, the major therapeutic challenge specific to ischemia, is currently unknown. Using in vitro models of ischemic-related stress, we documented that GC7, a specific inhibitor of a key enzyme in the eIF5A activation pathway, affords neuronal protection. We identified the preservation of mitochondrial function and thereby the prevention of toxic ROS generation as major processes of GC7 protection. To represent a thoughtful opportunity of clinical translation, we explored whether GC7 administration reduces the infarct volume and functional deficits in an in vivo transient focal cerebral ischemia (tFCI) model in mice. A single GC7 pre- or post-treatment significantly reduces the infarct volume post-stroke. Moreover, GC7-post-treatment significantly improves mouse performance in the rotarod and Morris water-maze, highlighting beneficial effects on motor and cognitive post-stroke deficits. Our results identify the targeting of the polyamine-eIF5A-hypusine axis as a new therapeutic opportunity and new paradigm of research in stroke and ischemic diseases.

Principal component analysis, a useful tool to study cyclin-dependent kinase-inhibitor's effect on cerebral ischaemia.

Stroke is a leading cause of acute death related in part to brain oedema, blood–brain barrier disruption and glial inflammation. A cyclin-dependant kinase inhibitor, (S)-roscovitine, was administered 90 min after onset on a model of rat focal cerebral ischaemia. Brain swelling and Evans Blue tissue extravasation were quantified after Evans Blue injection. Combined tissue Evans Blue fluorescence and immunofluorescence of endothelial cells (RECA1), microglia (isolectin-IB4) and astrocytes (glial fibrillary acidic protein) were analysed. Using a Student’s t-test or Mann–Whitney test, (S)-roscovitine improved recovery by more than 50% compared to vehicle (Mann–Whitney, P < 0.001), decreased significantly brain swelling by 50% (t-test, P = 0.0128) mostly in the rostral part of the brain. Main analysis was therefore performed on rostral cut for immunofluorescence to maximize biological observations (cut B). Evans Blue fluorescence decreased in (S)-roscovitine group compared to vehicle (60%, t-test, P = 0.049) and was further supported by spectrophotometer analysis (Mann–Whitney, P = 0.0002) and Evans Blue macroscopic photonic analysis (t-test, P = 0.07). An increase of RECA-1 intensity was observed in the ischaemic hemisphere compared to non-ischaemic hemisphere. Further study showed, in the ischaemic hemisphere that (S)-roscovitine treated group compared to vehicle, showed a decrease of: (i) endothelial RECA-1 intensity of about 20% globally, mainly located in the cortex (−28.5%, t-test, P = 0.03); (ii) Microglia’s number by 55% (t-test, P = 0.006) and modulated reactive astrocytes through a trend toward less astrocytes number (15%, t-test, P = 0.05) and astrogliosis (21%, t-test, P = 0.076). To decipher the complex relationship of these components, we analysed the six biological quantitative variables of our study by principal component analysis from immunofluorescence studies of the same animals. Principal component analysis differentiated treated from non-treated animals on dimension 1 with negative values in the treated animals, and positive values in the non-treated animals. Interestingly, stroke recovery presented a negative correlation with this dimension, while all other biological variables showed a positive correlation. Dimensions 1 and 2 allowed the identification of two groups of co-varying variables: endothelial cells, microglia number and Evans Blue with positive values on both dimensions, and astrocyte number, astrogliosis and brain swelling with negative values on dimension 2. This partition suggests different mechanisms. Correlation matrix analysis was concordant with principal component analysis results. Because of its pleiotropic complex action on different elements of the NeuroVascular Unit response, (S)-roscovitine may represent an effective treatment against oedema in stroke.

MiR-330 regulates Drp-1 mediated mitophagy by targeting PGAM5 in a rat model of permanent focal cerebral ischemia

Growing evidence have suggested that mitophagy could exert a neuroprotective role in brain ischemia by removing the damaged mitochondria. However the upstream mechanisms of mitophagy are remain unclear. We previously observed a decrease of miR-330 in a miRNA profile of plasma from patients within 3 h after a stroke. Our study further focused on the role and mechanism of miR-330 in mitophagy induced by hypoxia-ischemia (H/I) in rats. Cerebral ischemia model in rats was made with permanent middle cerebral artery occlusion (pMCAO). In vitro, ischemic model in primary neurons was established with oxygen-glucose deprivation. Various methods, including TTC staining, immunofluorescence staining, Western blot, ELISA, flow cytometry, and transmission electron microscopy were used to clarify the role of miR-330 after H/I, and whether miR-330/phosphoglycerate mutase family member 5 (PGAM5) axis could regulate dynamin-related protein 1 (Drp-1) mediated mitophagy. MiR-330 levels decreased both in rat plasma and in ipsilateral brain tissues after H/I. Pretreating animals with miR-330 antagomir could decrease cerebral infarction, edema, mortality, and apoptosis after 6-h pMCAO. PGAM5 was validated as a target of miR-330. MiR-330 agomir and antagomir transfection respectively decreased and increased the PGAM5 protein expression. MiR-330 could down-regulate mitophagy by inhibiting PGAM5-induced Drp1 dephosphorylation, thus reducing the recruitment of Drp1 to mitochondrial outer membrane and Drp1-mediated mitophagy after H/I. Our results suggest a role of miR-330 in regulating mitophagy. Our study suggested a novel miR-based intervention strategy for stroke.

Correction to: Application of Mathematical Modelling as a Tool to Analyze the EEG Signals in Rat Model of Focal Cerebral Ischemia

In the original publication of the article, figure 1 was published incorrectly. The corrected figure is given below.

Stress Induced tRNA Halves (tiRNAs) as Biomarkers for Stroke and Stroke Therapy; Pre-clinical Study

tiRNAs are small non-coding RNAs generated by angiogenin-mediated tRNA cleavage during cellular stress. Some tiRNAs were shown to be cytoprotective, while other reports indicate that the generation of tiRNAs is cytotoxic. We used rat model of focal cerebral ischemia–reperfusion (I/R) injury to study the generation and regulation of tiRNAs following in vivo I/R and the impact of neuroprotective therapy on their generation. tiRNAs were induced after I/R and Minocycline therapy reduced global tiRNA levels. Our results showed that tRNA cleavage is tRNA species specific, and neuroprotective treatment does not affect all tiRNA species. We also evaluated the temporal changes in several tRNA modifying enzymes and showed a correlation between their expression and tRNA cleavage. In conclusion, we show that tiRNAs can serve as biomarkers for stroke and stroke therapy, further adding them to the repertoire of tools that can be used to monitor and treat stroke.

Abstract WMP82: Inhibition of Thioredoxin Interacting Protein Attenuates Tissue Plasminogen Activator Induced Brain Damage Under Acute Hyperglycemia in Murine Stroke Model

Background and Hypothesis: Acute hyperglycemia (AHG) worsens stroke outcome and increases the risk of intracerebral hemorrhage after tissue plasminogen activator (tPA) treatment, independent of preexisting diabetes. We have previously reported that genetic deletion of thioredoxin interacting protein exerts neuroprotection after experimental stroke. Here we tested the hypothesis that pharmacological inhibition of TXNIP, with verapamil protects against tPA-induced brain damage under AHG in a mouse model of focal cerebral ischemia. Methods: Transient focal cerebral ischemia was induced by a 60 min middle cerebral artery occlusion (MCAO) followed by 23 h reperfusion in mice. AHG was induced by administration of 20% glucose (ip), 15 minutes before MCAO. Verapamil (0.015 mg/kg, iv) and tPA (iv), or saline was administered at 1 h post-occlusion. After 24 h of I/R, mice were tested for neurobehavioral outcome and were evaluated for infarct size and expression inflammatory mediators, and blood brain barrier markers. Results: AHG aggravated brain edema, blood brain disruption and neuroinflammation. Treatment with verapamil significantly reduced in the infarct size (41%, p&lt;0.05), hemorrhage (36%) and edema (36%, p&lt;0.05) compared to saline treated controls. Furthermore, verapamil significantly inhibited the TXNIP mediated activation of NLRP3-inflammsome and ameliorated blood brain barrier leakage (Table 1). Conclusion: Taken together, these data indicate that inhibition of TXNIP with verapamil may have therapeutic implications on ischemic stroke in the acute hyperglycemic condition.

Abstract TP100: Post-Transcriptional Inactivation of MMP-12 Immediately After Reperfusion Facilitates Neurological Recovery After Ischemic Stroke

Introduction: We recently showed in a rodent model of transient focal cerebral ischemia that matrix metalloproteinase-12 (MMP-12) induction in the ischemic brain promotes post-stroke blood-brain barrier disruption, apoptosis, demyelination, and infarction. The purpose of the present study is to investigate the role of elevated MMP-12 on post-stroke neurological function and to identify the time window of therapeutic opportunity for MMP-12 suppression. Methods: Adult male Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion and reperfusion. Cohorts of rats (n =8-15/group) were administered with either MMP-12 shRNA or scrambled shRNA sequence (vehicle control) expressing plasmids (1 mg/Kg; intravenous) formulated as nanoparticles. The differences in sample size of various cohorts were attributed to the exclusion criteria followed, high mortality rate in vehicle control-treated group, and sample size required for statistical analysis. To assess the reflex, balance, sensory, and motor functions, rats from various cohorts were subjected to modified neurological severity scoring (mNSS), adhesive removal test, beam walk test and rotarod test at day 1, 3 and 5 of reperfusion. To assess the time window of therapeutic opportunity, various cohorts of rats were treated at 5 min, 3h, and 6h of reperfusion. Investigators blinded to study groups analyzed all outcome parameters. Results: The post-stroke percent survival rate in cohorts treated with MMP12shRNA expressing plasmids range from 82 to 89 as compared to 67 in vehicle control-treated group. The cohort of rats treated at 5 min of reperfusion with MMP-12snRNA expressing plasmids showed significantly better functional recovery as assessed by various neurological tests. However, delayed administration of MMP-12snRNA expressing plasmid (either at 3h or 6h of reperfusion) failed to promote any significant improvement in post-stroke neurological recovery. Conclusions: Post-stroke induction of MMP-12 in the ischemic brain contributes to neurological deficits and impedes recovery. MMP-12 targeting treatments immediately after reperfusion could offer substantial therapeutic benefits.

Dl-NBP (Dl-3-N-Butylphthalide) Treatment Promotes Neurological Functional Recovery Accompanied by the Upregulation of White Matter Integrity and HIF-1α/VEGF/Notch/Dll4 Expression.

Dl-3-n-butylphthalide (dl-NBP) was approved by the FDA of China for the treatment of acute ischemic stroke. Dl-NBP has been shown to promote neurological functional recovery and enhance white matter integrity using an endothelin-1-induced focal permanent cerebral ischemia model, which could mimic those patients who have no opportunity to receive either tissue plasminogen activator (tPA) thrombolysis or endovascular therapy. However, it is not clear whether dl-NBP could promote neurological functional recovery in a focal transient cerebral ischemia model, which could mimic those patients who have the opportunity to receive either tPA thrombolysis or endovascular therapy. In this study, using a model of middle cerebral artery occlusion in mice, we aim to explore the effect of two-week dl-NBP treatment on neurological functional recovery after ischemic stroke as well as its underlying mechanism. Our results showed that dl-NBP treatment promoted functional recovery assessed by neurological scores and an adhesive remove test, and this improved the integrity of white matter after 60-min ischemia and 14-day reperfusion. In addition, dl-NBP increased the number of RECA-1 positive vessels and enhanced the expression of the tight junction protein occludin. More importantly, dl-NBP also promoted the expression of hypoxia-induced factor-1α, the vascular endothelial growth factor, Notch, and delta-like ligand 4. In conclusion, our study provides evidence that dl-NBP treatment could also promote functional recovery after focal transient ischemia stroke, and this recovery is associated with upregulated white matter integrity, microvessels, and the tight junction protein occludin. Our results suggested that, in future, dl-NBP may also be applied in clinic to promote functional recovery during the later phase of focal transient ischemic stroke.

Role of Sulfonylurea Receptor 1 and Glibenclamide in Traumatic Brain Injury: A Review of the Evidence.

Cerebral edema and contusion expansion are major determinants of morbidity and mortality after TBI. Current treatment options are reactive, suboptimal and associated with significant side effects. First discovered in models of focal cerebral ischemia, there is increasing evidence that the sulfonylurea receptor 1 (SUR1)—Transient receptor potential melastatin 4 (TRPM4) channel plays a key role in these critical secondary injury processes after TBI. Targeted SUR1-TRPM4 channel inhibition with glibenclamide has been shown to reduce edema and progression of hemorrhage, particularly in preclinical models of contusional TBI. Results from small clinical trials evaluating glibenclamide in TBI have been encouraging. A Phase-2 study evaluating the safety and efficacy of intravenous glibenclamide (BIIB093) in brain contusion is actively enrolling subjects. In this comprehensive narrative review, we summarize the molecular basis of SUR1-TRPM4 related pathology and discuss TBI-specific expression patterns, biomarker potential, genetic variation, preclinical experiments, and clinical studies evaluating the utility of treatment with glibenclamide in this disease.

Research Article Lack of effect of exercise on the expression profiles of mir-16, mir-21, mir-155, caspase3 and bcl2 in a rat model of focal cerebral ischemia

Research Article Lack of effect of exercise on the expression profiles of mir-16, mir-21, mir-155, caspase3 and bcl2 in a rat model of focal cerebral ischemia

Propolis ameliorates cerebral injury in focal cerebral ischemia/reperfusion (I/R) rat model via upregulation of TGF-β1

Neuroprotective impact of transforming growth factor β1 (TGF-β1) is increasingly recognized in different brain injuries. Propolis exhibits a broad spectrum of biological and pharmacological properties including neuroprotective action. The objective of the investigation was to explore the involvement of TGF-β1 signaling in the neuroprotective mechanism of propolis in I/R rats. In this study, focal cerebral ischemia model was built by middle cerebral artery occlusion (MCAO) for 2 h followed by reperfusion. The investigation was carried out on 48 rats that were arranged into four groups (n = 12): the sham group, I/R control group, I/R + propolis (50 mg/kg) group and I/R + propolis (100 mg/kg) group. The results revealed that propolis preserved rats against neuronal injury induced by cerebral I/R. It significantly reduced neurological deficit scores and improved motor coordination and locomotor activity in I/R rats. Propolis antagonized the damage induced by cerebral I/R through suppression of malondialdehyde (MDA) and elevation of reduced glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), brain-derived neurotropic factor (BDNF) and dopamine levels in the brain homogenates of I/R rats. Other ameliorations were also observed based on reduction of neurodegeneration and histological alterations in the brain tissues. These results also proposed that the neuroprotective effect of propolis might be related to upregulation of TGF-β1 and suppressed matrix metallopeptidase-9 (MMP9) mRNA expression.

IL-37: Novel neuroprotective effects after brain ischemia and reperfusion

Interleukin-1 (IL-1) is a central mediator of innate immunity and inflammation. IL-37 (IL-37), a newly described member of the IL-1 family, functions as a fundamental inhibitor of innate inflammation and immunity. The purpose of the present study was to determine the effects of interleukin-37 on neuron cells and on brain inflammation induced by brain ischemia/reperfusion (I/R). A transgenic mouse strain was generated to express human IL-37 (hIL-37Tg) and WT mice were subjected to (60 min) brain ischemia and followed by reperfusion (24 h), by using a mice model of transient focal cerebral ischemia induced by advancing a nylon mono-filament to occlude the middle cerebral artery (MCA). Infarct size was determined by triphenyltetrazolium chloride staining. The morphology of neurons in brain sections were examined by Nissl staining and cytokines/chemokines measured by ELIZA. IL-37Tg significantly reduced infarct size by 65.4% (P&lt;0.05) compared with WT after I/R. Reduced inflammation was associated with decreased leukocyte recruitment, and reduced release of IL-1β and TNFα, macrophage inflammatory protein-2 (MIP-2), MCP-1 and keratinocyte chemokine (KC) compared with WT (P&lt;0.05), whereas IL-10 was increased eight fold (P&lt;0.05). IL-37 significantly reduced cell death and increased Bcl-2 expression in neurons. Thus, IL-37 emerges as a key modulator of brain inflammation and has important translational implications for both the prevention and treatment of patients suffering from brain ischemia.

RNA sequencing reveals novel macrophage transcriptome favoring neurovascular plasticity after ischemic stroke

Blood monocytes/macrophages infiltrate the brain after ischemic stroke and critically influence brain injury and regeneration. We investigated stroke-induced transcriptomic changes of monocytes/macrophages by RNA sequencing profiling, using a mouse model of permanent focal cerebral ischemia. Compared to non-ischemic conditions, brain ischemia induced only moderate genomic changes in blood monocytes, but triggered robust genomic reprogramming in monocytes/macrophages invading the brain. Surprisingly, functional enrichment analysis of the transcriptome of brain macrophages revealed significant overrepresentation of biological processes linked to neurovascular remodeling, such as angiogenesis and axonal regeneration, as early as five days after stroke, suggesting a previously underappreciated role for macrophages in initiating post-stroke brain repair. Upstream Regulator analysis predicted peroxisome proliferator-activated receptor gamma (PPARγ) as a master regulator driving the transcriptional reprogramming in post-stroke brain macrophages. Importantly, myeloid cell-specific PPARγ knockout (mKO) mice demonstrated lower post-stroke angiogenesis and neurogenesis than wild-type mice, which correlated significantly with the exacerbation of post-stroke neurological deficits in mKO mice. Collectively, our findings reveal a novel repair-enhancing transcriptome in brain macrophages during post-stroke neurovascular remodeling. As a master switch controlling genomic reprogramming, PPARγ is a rational therapeutic target for promoting and maintaining beneficial macrophage functions, facilitating neurorestoration, and improving long-term functional recovery after ischemic stroke.

Neuroprotective effects of minocycline on focal cerebral ischemia injury: a systematic review.

To review the neuroprotective effects of minocycline in focal cerebral ischemia in animal models. By searching in the databases of PubMed, ScienceDirect, and Scopus, and considering the inclusion and exclusion criteria of the study. Studies were included if focal cerebral ischemia model was performed in mammals and including a control group that has been compared with a minocycline group. Written in languages other than English; duplicate data; in vitro studies and combination of minocycline with other neuroprotective agents were excluded. Neurological function of patients was assessed by National Institute of Health Stroke Scale, modified Rankin Scale, and modified Barthel Index. Neuroprotective effects were assessed by detecting the expression of inflammatory cytokines. We examined 35 papers concerning the protective effects of minocycline in focal cerebral ischemia in animal models and 6 clinical trials which had evaluated the neuroprotective effects of minocycline in ischemic stroke. These studies revealed that minocycline increases the viability of neurons and decreases the infarct volume following cerebral ischemia. The mechanisms that were reported in these studies included anti-inflammatory, antioxidant, as well as anti-apoptotic effects. Minocycline also increases the neuronal regeneration following cerebral ischemia. Minocycline has considerable neuroprotective effects against cerebral ischemia-induced neuronal damages. However, larger clinical trials may be required before using minocycline as a neuroprotective drug in ischemic stroke.

Wogonin improves functional neuroprotection for acute cerebral ischemia in rats by promoting angiogenesis via TGF-β1.

Previous studies showed that wogonin is a potential candidate for more effective treatment of neuronal and inflammatory disease and could offer neuroprotective activity in various models, but all these studies were in vitro. Our research aimed to investigate the neuroprotective effect of wogonin on focal cerebral ischemia in rats and uncover its potential mechanism. A total of 80 male SD rats were randomly divided into a sham operation group (Sham group, 20 rats), a normal saline group (NS group, 20 rats), and a wogonin intervention group (W2W group, 20 rats), while the remaining 20 rats were kept as a substitute. The model of focal cerebral ischemia (MCAO) was established by thread embolization. The neurological deficits were evaluated by the modified neurological deficit scale (mNSS). The laser confocal technique was used to observe the diameter, density, and total area of microvessel. Lastly, the expression of transforming growth factor-β1 (TGF-β1) was detected by Western blot. The mNSS scores of the NS group and Wn2W group were 6.57±1.13 and 4.39±0.92 respectively, and the difference between NS group and Wn2W group was statistically significant (P<0.05); the vascular diameter of the Wn2W group, Sham group, and NS group were 2.93±0.19, 4.24±0.16, and 3.56±0.22 µm respectively, and the differences among these groups were statistically significant (F=102.142, P<0.01). Furthermore, the differences in the vascular density (F=290.49, P<0.01) and total microvessel area (F=163.08, P<0.01) among these groups were also statistically significant. The expression of TGF-β1 in ischemic brain tissue of the Sham group, NS group, and Wn2W group were 0.46±0.14, 0.62±0.18, and 0.94±0.21 respectively, and the differences among these groups were statistically significant (F=102.142, P<0.01). Wogonin can markedly reduce nerve injury and improve nerve function in rats with cerebral ischemia, which may be related to the TGF-β1 pathway.