Activating Transcription Factor 3 Diminishes Ischemic Cerebral Infarct and Behavioral Deficit by Downregulating Carboxyl-Terminal Modulator Protein.

Activating transcription factor 3 (ATF3) is a stress-induced transcription factor and a familiar neuronal marker for nerve injury. This factor has been shown to protect neurons from hypoxic insult in vitro by suppressing carboxyl-terminal modulator protein (CTMP) transcription, and indirectly activating the anti-apoptotic Akt/PKB cascade. Despite prior studies in vitro, whether this neuroprotective pathway also exists in the brain in vivo after ischemic insult remains to be determined. In the present study, we showed a rapid and marked induction of ATF3 mRNA throughout ischemia-reperfusion in a middle cerebral artery (MCA) occlusion model. Although the level of CTMP mRNA was quickly induced upon ischemia, its level showed only a mild increase after reperfusion. With the gain-of-function approach, both pre- and post-ischemic administration of Ad-ATF3 ameliorated brain infarct and neurological deficits. Whereas, with the loss-of-function approach, ATF3 knockout (KO) mice showed bigger infarct and worse functional outcome after ischemia. In addition, these congenital defects were rescued upon reintroducing ATF3 to the brain of KO mice. ATF3 overexpression led to a lower level of CTMP and a higher level of p-Akt(473) in the ischemic brain. On the contrary, ATF3 KO resulted in upregulation of CTMP and downregulation of p-Akt(473) instead. Furthermore, post-ischemic CTMP siRNA knockdown led to smaller infarct and better behaviors. CTMP siRNA knockdown increased the level of p-Akt(473), but did not alter the ATF3 level in the ischemic brain, upholding the ATF3→CTMP signal cascade. In summary, our proof-of-principle experiments support the existence of neuroprotective ATF3→CTMP signal cascade regulating the ischemic brain. Furthermore, these results suggest the therapeutic potential for both ATF3 overexpression and CTMP knockdown for stroke treatment.

Metformin prevents stroke damage in non-diabetic female mice with chronic kidney disease.

Chronic kidney disease (CKD) worsens ischemic stroke severity in both patients and animals. In mice, these poorer functional outcomes are associated with decreased brain activity of AMP-activated protein kinase (AMPK), a molecule that recently emerged as a potential therapeutic target for ischemic stroke. The antidiabetic drug metformin, a well-known activator of AMPK, has improved stroke outcomes in diabetic patients with normal renal function. We investigated whether chronic metformin pre-conditioning can rescue AMPK activity and prevent stroke damage in non-diabetic mice with CKD. Eight-week-old female C57BL/6J mice were assigned to CKD or SHAM groups. CKD was induced through right kidney cortical electrocautery, followed by left total nephrectomy. Mice were then allocated to receive metformin (200 mg/kg/day) or vehicle for 5 weeks until stroke induction by transient middle cerebral artery occlusion (tMCAO). The infarct volumes were lower in CKD mice exposed to metformin than in vehicle-treated CKD mice 24 h after tMCAO. Metformin pre-conditioning of CKD mice improved their neurological score, grip strength, and prehensile abilities. It also enhanced AMPK activation, reduced apoptosis, increased neuron survival and decreased microglia/macrophage M1 signature gene expression as well as CKD-induced activation of the canonical NF-κB pathway in the ischemic lesions of CKD mice.

Association of Multiple Gene Polymorphisms Including Homozygous NUDT15 R139C With Thiopurine Intolerance During the Treatment of Acute Lymphoblastic Leukemia.

Although thiopurine is a crucial drug for treating acute lymphoblastic leukemia, individual variations in intolerance are observed due to gene polymorphisms. A 3-year-old boy with B-cell precursor acute lymphoblastic leukemia who was administered thiopurine developed mucositis, sepsis, and hemophagocytic lymphohistiocytosis due to prolonged hematologic toxicity, chronic disseminated candidiasis, and infective endocarditis that triggered multiple brain infarctions. The patient was found to harbor 3 gene polymorphisms associated with thiopurine intolerance including homozygous NUDT15 R139C, heterozygous ITPA C94A, and homozygous MTHFR C677T and heterozygous RFC1 G80A. Thus, the combined effect of intolerance via multiple gene polymorphisms should be considered in case of unexpected adverse reactions.

Single Cortical Microinfarcts Lead to Widespread Microglia/Macrophage Migration Along the White Matter.

Loss of cognitive function with aging is a complex and poorly understood process. Recently, clinical research has linked the occurrence of cortical microinfarcts to cognitive decline. Cortical microinfarcts form following the occlusion of penetrating vessels and are considered to be restricted to the proximity of the occluded vessel. Whether and how such local events propagate and affect remote brain regions remain unknown. To this end, we combined histological analysis and longitudinal diffusion tensor imaging (DTI), following the targeted-photothrombotic occlusion of single cortical penetrating vessels. Occlusions resulted in distant tissue reorganization across the mouse brain. This remodeling co-occurred with the formation of a microglia/macrophage migratory path along subcortical white matter tracts, reaching the contralateral hemisphere through the corpus callosum and leaving a microstructural signature detected by DTI-tractography. CX3CR1-deficient mice exhibited shorter trail lengths, differential remodeling, and only ipsilateral white matter tract changes. We concluded that microinfarcts lead to brain-wide remodeling in a microglial CX3CR1-dependent manner.

Astragaloside IV alleviates ischemia reperfusion-induced apoptosis by inhibiting the activation of key factors in death receptor pathway and mitochondrial pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Apoptosis plays an important role in cerebral ischemia-reperfusion injury and triggers a series of pathological changes which may even be life-threatening. Astragaloside-IV (AS-IV), a natural compound extracted from Astragalus (Astragalus membranaceus (Fisch.) Bunge., Leguminosae, Huangqi in Chinese), showed neuroprotective effects in the study of cerebral ischemia-reperfusion injury. In this study we investigate the effects of AS-IV on apoptosis induced by transient cerebral ischemia and reperfusion in rats, as well as the associated regulatory factors. METHODS: AS-IV was administrated to male Sprague-Dawley (SD) rats after transient cerebral ischemia and reperfusion surgery (12.5, 25, and 50 mg/kg, once per day, continued for 7 days after surgey). After seven days of continuous administration, neurological function, cerebral infarction volume, and pathological changes of brain tissue were detected. Fas, FasL, Caspase-8, Bax, and Bcl-2 mRNA levels were determined by real-time PCR. Caspase-8, Bid, Cytochrome C (Cyto C), cleaved Caspase-3 proteins were determined by western blot and immunohistochemistry was used to quantify Cyto C. RESULTS: AS-IV significantly attenuated the neurological deficit in rats with ischemica-reperfusion injury, and reduced cerebral infarction and neuronal apoptosis. AS-IV inhibited the mRNA upregulation of Fas, FasL, Caspase-8, and Bax/Bcl-2. Furthermore, the protein level of apoptosis cytokines Caspase-8, Bid, cleaved Caspase-3 and Cyto C were also inhibited after ischemia reperfusion, suggesting that AS-IV might alleviate ischemia reperfusion-induced apoptosis by inhibiting the activation of key factors in death receptor pathway and mitochondrial pathway.

TGFα preserves oligodendrocyte lineage cells and improves white matter integrity after cerebral ischemia.

Transforming growth factor α (TGF-α) has been reported to play important roles in neurogenesis and angiogenesis in the injured brain. The present study characterizes a novel role for TGFα in oligodendrocyte lineage cell survival and white matter integrity after ischemic stroke. Three days after transient (60 min) middle cerebral artery occlusion (tMCAO), TGFα expression was significantly increased in microglia/macrophages and neurons. Expression of the receptor of TGFα-epidermal growth factor receptor (EGFR)-was increased in glial cells after ischemia, including in oligodendrocyte lineage cells. TGFα knockout enlarged brain infarct volumes and exacerbated cell death in oligodendrocyte precursor cells (OPCs) and oligodendrocytes three days after tMCAO. TGFα-deficient mice displayed long-term exacerbation of sensorimotor deficits after tMCAO, and these functional impairments were accompanied by loss of white matter integrity and impaired oligodendrocyte replacement. In vitro studies confirmed that 5 or 10 ng/mL TGFα directly protected OPCs and oligodendrocytes against oxygen and glucose deprivation (OGD)-induced cell death, but exerted no effects on OPC differentiation. Further studies identified STAT3 as a key transcription factor mediating the effects of TGFα on OPCs and oligodendrocytes. In conclusion, TGFα provides potent oligodendrocyte protection against cerebral ischemia, thereby maintaining white matter integrity and improving neurological recovery after stroke.

Genotype-Phenotype Correlation in Long-Term Cohort of Japanese Patients with Moyamoya Disease.

BACKGROUND: Homozygosity of this p.R4810K founder variant of RNF213moyamoya disease (MMD) susceptibility gene is known to influence the severity of the clinical disease phenotype at disease onset. However, the association between this genotype and long-term clinical manifestations has remained unclear. OBJECTIVES: The principal goal of this study was to investigate whether and how the p.R4810K variant of RNF213influences the long-term phenotype in Japanese patients with MMD. METHOD: This retrospective cohort study included 94 Japanese patients with MMD who underwent direct or combined bypass for revascularization with the p.R4810K genotype determined in our hospital. The following phenotypic parameters were analyzed at disease onset and over a long-term period: age and initial presentation at onset, recurrent stroke after initial revascularization, and final modified Rankin Scale. RESULTS: The p.R4810K genotype was significantly associated with the phenotype at onset, especially in younger patients. Over a median follow-up period of 100 months, recurrent stroke occurred in 6 out of 94 patients: none out of 5 patients with the homozygous variant, 5 out of 64 with the heterozygous variant, and 1 out of 25 in the wild-type group. There were no significant differences among the genotypes. In particular, recurrent cerebral hemorrhage occurred in 5 patients, all possessing the heterozygous variant. The log-rank test showed no difference between the genotypes in the stroke-free survival rate. Furthermore, the p.R4810K genotype was not associated with a poor functional condition. CONCLUSIONS: The p.R4810K founder variant of RNF213 affects the phenotype at disease onset. However, the optimal revascularization may be effective, regardless of the genotype, even for the homozygous variant, which has been thought to be the most pathogenic. This genotype may not strongly influence the long-term clinical manifestations or poor prognosis in MMD.

Neuromodulatory Effect of NLRP3 and ASC in Neonatal Hypoxic Ischemic Encephalopathy.

BACKGROUND: Following birth asphyxia there is a robust inflammatory response. NLRP3 is a receptor of the innate immune system. Upon activation, NLRP3 forms an inflammasome together with ASC and procaspase-1 to mediate release of IL-1ß and IL-18. NLRP3 has previously been shown to be upregulated following neonatal hypoxic-ischemic (HI) brain injury in mice, but with no early effect on brain injury. OBJECTIVE: We aimed to evaluate if deficiency of NLRP3 or ASC protects against neonatal HI brain damage 7 days after hypoxia-ischemia. METHODS: C57BL/6J, NLRP3-/-, and ASC-/- mice were subjected to unilateral common carotid artery ligation followed by hypoxia at P9. Brain infarction, apoptosis, and microglial response were evaluated, as well as total RNA sequencing and examination of plasma levels of systemic proinflammatory cytokines. RESULTS: NLRP3-/- mice showed significantly increased brain infarction volumes compared to wild-type (Wt) mice, while ASC-/- mice showed reduced brain infarction volumes after neonatal hypoxia-ischemia. The amount of activated microglia was increased in NLRP3-/- mice, while decreased in ASC-/- mice compared to Wt mice. Total RNA sequencing showed an impaired inflammatory transcriptional response in the hippocampus of NLRP3-/- mice. Plasma levels of IL-1ß and IL-18 were not affected, but TNF was lower in NLRP3-/- and ASC-/- mice compared to Wt mice. CONCLUSION: ASC deficiency is neuroprotective in neonatal HI brain damage in mice, while NLRP3 deficiency increases brain damage.

Methionine Sulfoxide Reductase-B3 Risk Allele Implicated in Alzheimer's Disease Associates with Increased Odds for Brain Infarcts.

Genome-wide association studies identified a single nucleotide polymorphism (SNP) in the MSRB3 gene encoding Methionine Sulfoxide Reductase-B3 (MsrB3) to be associated with the risk for low hippocampal volume and late onset Alzheimer's disease (AD). Subsequently, we identified AD-associated abnormal patterns of neuronal and vascular MsrB3 expression in postmortem hippocampi. The present study investigated the relationship between the MSRB3 SNP rs61921502, G (minor/risk allele) and MRI measures of brain injury including total brain volume, hippocampal volume, and white matter hyperintensities using linear regression models; the presence of brain infarcts using logistic regression models; and the incidence of stroke, dementia, and AD using Cox proportional hazards models in 2,038 Framingham Heart Study Offspring participants with MRI administered close to examination cycle 7 (1998-2001). Participants with neurological conditions that impede evaluation of vascular pathology by MRI, i.e., brain tumors, multiple sclerosis, and major head trauma, were excluded from the study. When adjusted for age and age squared at MRI exam, sex, and presence of Apolipoproteinɛ4 allele (APOE4), individuals with MSRB3 rs61921502 minor allele had increased odds for brain infarcts on MRI compared to those with no minor allele. However, in stratified analyses, MSRB3 rs61921502 minor allele was significantly associated with increased odds for MRI brain infarcts only in the absence of APOE4.

Biliverdin administration regulates the microRNA-mRNA expressional network associated with neuroprotection in cerebral ischemia reperfusion injury in rats.

Inflammatory response has an important role in the outcome of cerebral ischemia reperfusion injury (CIR). Biliverdin (BV) administration can relieve CIR in rats, but the mechanism remains unknown. The aim of the present study was to explore the expressional network of microRNA (miRNA)­mRNA in CIR rats following BV administration. A rat middle cerebral artery occlusion model with BV treatment was established. After neurobehavior was evaluated by neurological severity scores (NSS), miRNA and mRNA expressional profiles were analyzed by microarray technology from the cerebral cortex subjected to ischemia and BV administration. Then, bioinformatics prediction was used to screen the correlation between miRNA and mRNA, and 20 candidate miRNAs and 33 candidate mRNAs were verified by reverse transcription­quantitative polymerase chain reaction. Furthermore, the regulation relationship between ETS proto­oncogene 1 (Ets1) and miRNA204­5p was examined by luciferase assay. A total of 86 miRNAs were differentially expressed in the BV group compared with the other groups. A total of 10 miRNAs and 26 candidate genes were identified as a core 'microRNA­mRNA' regulatory network that was linked with the functional improvement of BV administration in CIR rats. Lastly, the luciferase assay results confirmed that miRNA204­5p directly targeted Ets1. The present findings suggest that BV administration may regulate multiple miRNAs and mRNAs to improve neurobehavior in CIR rats, by influencing cell proliferation, apoptosis, maintaining ATP homeostasis, and angiogenesis.

Long non-coding RNA HOTAIR promotes ischemic infarct induced by hypoxia through up-regulating the expression of NOX2.

BACKGROUND: Mounting studies have illustrated an important role of HOTAIR in cancer progress, but few studies have reported its function in brain disease, including nerve cell-associated ischemic infarct. This study aimed to investigate the function of HOTAIR in ischemic infarct, involving its association with the level of NOX2 during hypoxia-induced ischemic infarct. METHODS: Ischemic infarct mice model was established by hypoxia induction, and cerebral dysfunction was evaluated with the surface cerebral blood flow in the ipsilateral hemisphere. HOTAIR expression in isolated infarction lesion and NOX2 protein level in the circulation were detected. HT22 cells were subjected to hypoxia treatment in vitro for functional studies, including TUNEL-positive cells detection for apoptosis analysis. RESULTS: HOTAIR expression was significantly up-regulated in infarction lesion from ischemic infarct mice, in line with increased NOX2 production, while similar results were also observed in hypoxia treated HT22 cells, which was then reversed by HOTAIR interference. Functional studies demonstrated that HOTAIR showed positive regulation on TUNEL-positive cells and apoptosis. Further in vitro study confirmed that HOTAIR silencing could improve cerebral function of ischemic infarct mice, and markedly decreased NOX2 production in the circulation. CONCLUSION: High expression of HOTAIR promoted the onset of ischemic infarct induced by hypoxia. Moreover, the finding showed that HOTAIR promoted ischemic infarct induced by hypoxia through regulating NOX2 expression, which could add our understanding of the molecular mechanisms in ischemic infarct.

Receptor-interacting protein kinase 3-mediated programmed cell necrosis in rats subjected to focal cerebral ischemia-reperfusion injury.

In the current study, the activation of tumor necrosis factor-α receptor 1 (TNFR1) and receptor-interacting protein kinase 3 (RIP3) were investigated following cerebral ischemia-reperfusion injury (CIRI). Healthy SD rats were randomly divided into 3 groups: Sham operation group, model group and inhibitor group. The model group and inhibitor group were further divided into 4 subgroups of 6, 12, 24 and 72 h following CIRI. Using right middle cerebral artery embolization, the CIRI model was generated. To confirm that the CIRI model was established, neurological scores, TTC staining and brain water content measurements were conducted. Immunohistochemistry and western blotting were conducted to investigate the expression of TNFR1 and RIP3 in the cerebral cortex. It was observed that nerve cell necrosis occurred following 6 h of CIRI. The appearance of necrotic cells was gradually increased with increasing CIRI duration. TNFR1 and RIP3 were positively expressed following 6 h of CIRI. With increasing durations of CIRI, the protein expression levels of TNFR1 and RIP3 were significantly increased. Pre­administration with Z-VAD-FMK (zVAD) significantly increased the protein level of RIP3, however, had no effect on the levels of TNFR1, and was accompanied by a reduction in necrosis. In conclusion, RIP3­mediated cell necrosis was enhanced by caspase blockade zVAD and the function of zVAD was independent of TNFR1 signaling following IR.

Isoflurane preconditioning provides neuroprotection against stroke by regulating the expression of the TLR4 signalling pathway to alleviate microglial activation.

Excessive microglial activation often contributes to inflammation-mediated neurotoxicity in the ischemic penumbra during the acute stage of ischemic stroke. Toll-like receptor 4 (TLR4) has been reported to induce microglial activation via the NF-κB pathway. Isoflurane preconditioning (IP) can provide neuroprotection and inhibit microglial activation. In this study, we investigated the roles of the TLR4 signalling pathway in IP to exert neuroprotection following ischemic stroke in vivo and in vitro. The results showed that 2% IP alleviated neurological deficits, reduced the infarct volume, attenuated apoptosis and weakened microglial activation in the ischemic penumbra. Furthermore, IP down-regulated the expression of HSP 60, TLR4 and MyD88 and up-regulated inhibitor of IκB-α expression compared with I/R group in vivo. In vitro, 2% IP and a specific inhibitor of TLR4, CLI-095, down-regulated the expression of TLR4, MyD88, IL-1ß, TNF-α and Bax, and up-regulated IκB-α and Bcl-2 expression compared with OGD group. Moreover, IP and CLI-095 attenuated microglial activation-induced neuronal apoptosis, and overexpression of the TLR4 gene reversed the neuroprotective effects of IP. In conclusion, IP provided neuroprotection by regulating TLR4 expression directly, alleviating microglial activation and neuroinflammation. Thus, inhibiting the activation of microglial activation via TLR4 may be a new avenue for stroke treatment.

MTHFR C677T and prothrombin G20210A mutations in a woman from Dalmatia with silent brain infarction. .

A 55-year-old, previously healthy woman, presented with frequent headaches. She had no neurological disturbances, but had a positive family history; her father died from stroke. Magnetic resonance imaging showed brain infarction; therefore detailed diagnostic evaluation of thrombophilia markers and genetic testing were performed. The patient was found to be homozy- gous for the C677T mutation of the methylenetetrahydrofolate reductase gene and heterozygous for the mutation of the prothrombin G20210A gene. No other cause of cerebral infarction was found in the patient.

Neuroprotective effects of rhynchophylline against ischemic brain injury via regulation of the Akt/mTOR and TLRs signaling pathways.

Rhynchophylline (Rhy) is an alkaloid isolated from Uncaria which has long been recommended for the treatment of central nervous diseases. In our study, the neuroprotective effect of Rhy was investigated in a stroke model, namely permanent middle cerebral artery occlusion (pMCAO). Rats were injected intraperitoneally once daily for four consecutive days before surgery and then received one more injection after surgery. The protein and mRNA levels of p-Akt, p-mTOR, apoptosis-related proteins (p-BAD and cleaved caspase-3), TLR2/4/9, NF-κB, MyD88, BDNF and claudin-5 were examined. Following pMCAO, Rhy treatment not only ameliorated neurological deficits, infarct volume and brain edema, but also increased claudin-5 and BDNF expressions (p < 0.05). Moreover, Rhy could activate PI3K/Akt/mTOR signaling while inhibiting TLRs/NF-κB pathway. Wortmannin, a selective PI3K inhibitor, could abolish the neuroprotective effect of Rhy and reverse the increment in p-Akt, p-mTOR and p-BAD levels. In conclusion, we hypothesize that Rhy protected against ischemic damage, probably via regulating the Akt/mTOR pathway.

[Frequency of allele polymorphism of immune proteasome catalytic subunits in patients with ischemic stroke].

Frequency of allelic variants of proteasome subunits genes LMP2 (Arg60 --> His) and PSMA6 were determined in patients with ischemic stroke using real-time PCR. Allelic variants of PSMA6 were disposed in the next manner: C/C - 80.2%, C/G - 19.8%, G/G--were not (in control) and C/C - 75.5%, C/G - 21.4%, G/G - 3.1% (P = 0.22) in patients with IS. It was shown that distribution of LMP2 allelic variants was the following: Arg/Arg - 53.3%, Arg/His - 43.5%, His/His - 6.7% in control and Arg/Arg - 55.9%, Arg/His - 34.3%, His/His - 9.8% in IS group (P > 0.05). The data show that LMP2 and PSMA6 gene polymorphism is not a risk factor of ischemic stroke in Ukrainian population.

Drp1 stabilizes p53 on the mitochondria to trigger necrosis under oxidative stress conditions in vitro and in vivo.

Oxidative-stress-induced necrosis is considered to be one of the main pathological mediators in various neurological disorders, such as brain ischaemia. However, little is known about the mechanism by which cells modulate necrosis in response to oxidative stress. In the present study, we showed that Drp1 (dynamin-related protein 1), a primary mitochondrial fission protein, stabilizes the well-known stress gene p53 and is required for p53 translocation to the mitochondria under conditions of oxidative stress. We found that Drp1 binding to p53 induced mitochondria-related necrosis. In contrast, inhibition of Drp1 hyperactivation by Drp1 siRNA reduced necrotic cell death in cell cultures exposed to oxidative stress. Most significantly, we demonstrated that inhibition of Drp1 by the Drp1 peptide inhibitor P110, which was developed recently by our group, abolished p53 association with the mitochondria and reduced brain infarction in rats subjected to brain ischaemia/reperfusion injury. Taken together, these findings reveal a novel mechanism of Drp1 hyperactivation in the induction of mitochondrial damage and subsequent cell death. We propose that a Drp1 inhibitor such as P110 is a possible therapeutic agent for diseases in which hyperactivated Drp1 contributes to the pathology.

CX3CR1 deficiency suppresses activation and neurotoxicity of microglia/macrophage in experimental ischemic stroke.

BACKGROUND: Chemokine (C-X3-C motif) ligand 1 (CX3CL1)/ CX3C chemokine receptor 1 (CX3CR1) signaling is important in modulating the communication between neurons and resident microglia/migrated macrophages in the central nervous system (CNS). Although CX3CR1 deficiency is associated with an improved outcome following ischemic brain injury, the mechanism of this observation is largely unknown. The aim of this study was to investigate how CX3CR1 deficiency influences microglia/macrophage functions in the context of its protection following brain ischemia. METHODS: Wild-type (WT) and CX3CR1-deficient (CX3CR1⁻/⁻) mice were subjected to transient middle cerebral artery occlusion (MCAO) and reperfusion. The ischemic brain damage was monitored by rodent high-field magnetic resonance imaging. Neurological deficit was assessed daily. Neuronal apoptotic death and reactive oxygen species (ROS) production were analyzed by immunostaining and live imaging. Activation/inflammatory response of microglia/macrophage were assessed using immunohistochemistry, flow cytometry, 5-bromo-2-deoxyuridine labeling, cytokine ELISA, and real-time PCR. RESULTS: CX3CR1⁻/⁻ mice displayed significantly smaller infarcts and less severe neurological deficits compared to WT controls, following MCAO. In addition, CX3CR1⁻/⁻ MCAO mice displayed fewer apoptotic neurons and reduced ROS levels. Impaired CX3CR1 signaling abrogated the recruitment of monocyte-derived macrophages from the periphery, suppressed the proliferation of CNS microglia and infiltrated macrophage, facilitated the alternative activation (M2 state) of microglia/macrophages, and attenuated their ability to synthesize and release inflammatory cytokines. CONCLUSION: Our results suggest that inhibition of CX3CR1 signaling could function as a therapeutic modality in ischemic brain injury, by reducing recruitment of peripheral macrophages and expansion/activation of CNS microglia and macrophages, resulting in protection of neurological function.