H2S prevents peripheral immune cell invasion, increasing [Ca2+]i and excessive phagocytosis following hypoxia-ischemia injury in neonatal mice.

We previously reported that L-Cysteine, H2S donor, remarkably attenuated neuroinflammation following hypoxia-ischemia (HI) brain injury in neonatal mice. However, its anti-inflammatory mechanism for HI insult is still unknown. The study focus on the effects of L-Cysteine on immune cell populations, Ca2+ mobilization and phagocytosis after neonatal HI. We found that L-Cysteine treatment skewed CD11b+/CD45low microglia and CD11b+/CD45high brain monocytes/macrophages towards a more anti-inflammatory property 72 h after HI-injured brain. Moreover, L-Cysteine treatment reduced cerebral infiltration of CD4 T cells 7 days following HI insult. Furthermore, CD4 T cell subset analysis revealed that L-Cysteine treatment decreased Th1 and Th2 counts, while increased Th17/Th2 ratio. Moreover, L-Cysteine treatment suppressed LPS-induced cytosolic Ca2+ and LPS-stimulated phagocytosis in primary microglia. The anti-inflammatory effect of L-Cysteine was associated with improving neurobehavioral impairment following HI insult. Our results demonstrate L-Cysteine treatment suppressed the invasion of peripheral immune cells, increasing [Ca2+]i and excessive phagocytosis to improve neurobehavioral deficits following hypoxia-ischemia injury in neonatal mice by H2S release.

Microglia and Macrophages in the Pathological Central and Peripheral Nervous Systems.

Microglia, the immunocompetent cells in the central nervous system (CNS), have long been studied as pathologically deteriorating players in various CNS diseases. However, microglia exert ameliorating neuroprotective effects, which prompted us to reconsider their roles in CNS and peripheral nervous system (PNS) pathophysiology. Moreover, recent findings showed that microglia play critical roles even in the healthy CNS. The microglial functions that normally contribute to the maintenance of homeostasis in the CNS are modified by other cells, such as astrocytes and infiltrated myeloid cells; thus, the microglial actions on neurons are extremely complex. For a deeper understanding of the pathophysiology of various diseases, including those of the PNS, it is important to understand microglial functioning. In this review, we discuss both the favorable and unfavorable roles of microglia in neuronal survival in various CNS and PNS disorders. We also discuss the roles of blood-borne macrophages in the pathogenesis of CNS and PNS injuries because they cooperatively modify the pathological processes of resident microglia. Finally, metabolic changes in glycolysis and oxidative phosphorylation, with special reference to the pro-/anti-inflammatory activation of microglia, are intensively addressed, because they are profoundly correlated with the generation of reactive oxygen species and changes in pro-/anti-inflammatory phenotypes.

Association of neonatal inflammatory markers and perinatal stroke subtypes.

OBJECTIVE: To examine the relationship between neonatal inflammatory cytokines and perinatal stroke using a systems biology approach analyzing serum and blood-spot cytokines from 47 patients. METHODS: This was a population-based, controlled cohort study with prospective and retrospective case ascertainment. Participants were recruited through the Alberta Perinatal Stroke Project. Stroke was classified as neonatal arterial ischemic stroke (NAIS), arterial presumed perinatal ischemic stroke (APPIS), or periventricular venous infarction (PVI). Biosamples were stored blood spots (retrospective) and acute serum (prospective). Controls had comparable gestational and maternal ages. Sixty-five cytokines were measured (Luminex). Hierarchical clustering analysis was performed to create heat maps. The Fisher linear discriminant analysis was used to create projection models to determine discriminatory boundaries between stroke types and controls. RESULTS: A total of 197 participants were analyzed (27 with NAIS, 8 with APPIS, 12 with PVI, 150 controls). Cytokines were quantifiable with quality control measures satisfied (standards testing, decay analysis). Linear discriminant analysis had high accuracy in using cytokine profiles to separate groups. Profiles in participants with PVI and controls were similar. NAIS separation was accurate (sensitivity 77%, specificity 97%). APPIS mapping was also distinguishable from NAIS (sensitivity 86%, specificity 99%). Classification tree analysis generated similar diagnostic accuracy. CONCLUSIONS: Unique inflammatory biomarker signatures are associated with specific perinatal stroke diseases. Findings support an acquired pathophysiology and suggest the possibility that at-risk pregnancies might be identified to develop prevention strategies. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that differences in acute neonatal serum cytokine profiles can discriminate between patients with specific perinatal stroke diseases and controls.

Brain-to-cervical lymph node signaling after stroke.

After stroke, peripheral immune cells are activated and these systemic responses may amplify brain damage, but how the injured brain sends out signals to trigger systemic inflammation remains unclear. Here we show that a brain-to-cervical lymph node (CLN) pathway is involved. In rats subjected to focal cerebral ischemia, lymphatic endothelial cells proliferate and macrophages are rapidly activated in CLNs within 24 h, in part via VEGF-C/VEGFR3 signalling. Microarray analyses of isolated lymphatic endothelium from CLNs of ischemic mice confirm the activation of transmembrane tyrosine kinase pathways. Blockade of VEGFR3 reduces lymphatic endothelial activation, decreases pro-inflammatory macrophages, and reduces brain infarction. In vitro, VEGF-C/VEGFR3 signalling in lymphatic endothelial cells enhances inflammatory responses in co-cultured macrophages. Lastly, surgical removal of CLNs in mice significantly reduces infarction after focal cerebral ischemia. These findings suggest that modulating the brain-to-CLN pathway may offer therapeutic opportunities to ameliorate systemic inflammation and brain injury after stroke.

STAT6/Arg1 promotes microglia/macrophage efferocytosis and inflammation resolution in stroke mice.

Efferocytosis, or phagocytic clearance of dead/dying cells by brain-resident microglia and/or infiltrating macrophages, is instrumental for inflammation resolution and restoration of brain homeostasis after stroke. Here, we identify the signal transducer and activator of transcription 6/arginase1 (STAT6/Arg1) signaling axis as a potentially novel mechanism that orchestrates microglia/macrophage responses in the ischemic brain. Activation of STAT6 was observed in microglia/macrophages in the ischemic territory in a mouse model of stroke and in stroke patients. STAT6 deficiency resulted in reduced clearance of dead/dying neurons, increased inflammatory gene signature in microglia/macrophages, and enlarged infarct volume early after experimental stroke. All of these pathological changes culminated in an increased brain tissue loss and exacerbated long-term functional deficits. Combined in vivo analyses using BM chimeras and in vitro experiments using microglia/macrophage-neuron cocultures confirmed that STAT6 activation in both microglia and macrophages was essential for neuroprotection. Adoptive transfer of WT macrophages into STAT6-KO mice reduced accumulation of dead neurons in the ischemic territory and ameliorated brain infarction. Furthermore, decreased expression of Arg1 in STAT6-/- microglia/macrophages was responsible for impairments in efferocytosis and loss of antiinflammatory modality. Our study suggests that efferocytosis via STAT6/Arg1 modulates microglia/macrophage phenotype, accelerates inflammation resolution, and improves stroke outcomes.

Glatiramer acetate reduces infarct volume in diabetic mice with cerebral ischemia and prevents long-term memory loss.

Stroke is currently the second leading cause of death in industrialized countries and the second cause of dementia after Alzheimer's disease. Diabetes is an independent risk factor for stroke that exacerbates the severity of lesions, disability and cognitive decline. There is increasing evidence that sustained brain inflammation may account for this long-term prejudicial outcome in diabetic patients in particular. We sought to demonstrate that experimental permanent middle cerebral artery occlusion (pMCAo) in the diabetic mouse aggravates stroke, induces cognitive decline, and is associated with exacerbated brain inflammation, and that these effects can be alleviated and/or prevented by the immunomodulator, glatiramer acetate (GA). Male diabetic C57Bl6 mice (streptozotocin IP) subjected to permanent middle cerebral artery occlusion (pMCAo), were treated by the immunomodulator, GA (Copaxone®) (1 mg/kg daily, sc) until 3 or 7 days post stroke. Infarct volume, brain pro- and anti-inflammatory mediators, microglial/macrophage density, and neurogenesis were monitored during the first week post stroke. Neurological sensorimotor deficit, spatial memory and brain deposits of Aß40 and Aß42 were assessed until six weeks post stroke. In diabetic mice with pMCAo, proinflammatory mediators (IL-1ß, MCP1, TNFα and CD68) were significantly higher than in non-diabetic mice. In GA-treated mice, the infarct volume was reduced by 30% at D3 and by 40% at D7 post stroke (P < 0.05), sensorimotor recovery was accelerated as early as D3, and long-term memory loss was prevented. Moreover, proinflammatory mediators significantly decreased between D3 (COX2) and D7 (CD32, TNFα, IL-1ß), and neurogenesis was significantly increased at D7. Moreover, GA abrogates the accumulation of insoluble Aß40. This work is the first one to evidence that the immunomodulatory drug GA reduces infarct volume and proinflammatory mediators, enhances early neurogenesis, accelerates sensorimotor recovery, and prevents long-term memory loss in diabetic mice with pMCAo.

DUSP14 rescues cerebral ischemia/reperfusion (IR) injury by reducing inflammation and apoptosis via the activation of Nrf-2.

Ischemic stroke is the second most common cause of death, a major cause of acquired disability in adults. However, the pathogenesis that contributes to ischemic stroke has not been fully understood. Dual-specificity phosphatase 14 (DUSP14, also known as MKP6) is a MAP kinase phosphatase, playing important role in regulating various cellular processes, including oxidative stress and inflammation. However, its effects on cerebral ischemia/reperfusion (IR) are unclear. In the study, we found that DUSP14 expression was decreased responding to IR surgery. Over-expressing DUSP14 reduced the infarction volume of cerebral IR mice. Cognitive dysfunction was also improved in mice with DUSP14 over-expression. Promoting DUSP14 expression markedly reduced the activation of glial cells, as evidenced by the decreases in GFAP and Iba-1 expressions in mice with cerebral IR injury. In addition, inflammatory response induced by cerebral IR injury was inhibited in DUSP14 over-expressed mice, as proved by the reduced expression of tumor necrosis factor (TNF)-α and interleukin 1ß (IL-1ß). Furthermore, oxidative stress was markedly reduced by DUSP14 over-expression through elevating nuclear factor-erythroid 2 related factor 2 (Nrf-2) signaling pathway. Importantly, we found that DUSP14 could interact with Nrf-1, which thereby protected mice against cerebral IR injury. In vitro, we also found that repressing Nrf-2 expression abrogated DUSP14 over-expression-reduced inflammation and ROS generation. Consistent with the anti-inflammatory effect of DUSP14, reducing the production of reactive oxygen species (ROS) also down-regulated TNF-α and IL-1ß expressions. Collectively, elevated DUSP14 alleviated brain damage from cerebral IR injury through Nrf-2-regulated anti-oxidant signaling pathway, and the restraining of inflammatory response. These results suggested that DUSP14 might be a potential therapeutic target to prevent ischemic stroke.

Elevated Tumor Necrosis Factor-a-induced Protein 8-like 2 mRNA from Peripheral Blood Mononuclear Cells in Patients with Acute Ischemic Stroke.

Background: Tumor necrosis factor-a-induced protein 8-like 2 (TIPE2) is a novel regulator of immunity and protects against experimental stroke. However, the expression and function of TIPE2 in patients with acute ischemic stroke has not been well demonstrated. Methods: A total of 182 consecutive patients with acute ischemic stroke and 40 healthy controls were included during November 2015 to June 2016. The mRNA levels of TIPE2, interleukin(IL)-1ß, IL-10, IL-6, nuclear factor(NF)-κß, activator protein(AP)-1, interferon(IFN)-γ and tumor necrosis factor(TNF)-α from peripheral blood mononuclear cells were determined using real time quantitative reverse transcriptase polymerase chain reaction. The severity of stroke was assessed using the National Institutes of Health Stroke Scale (NIHSS) score. Results: The median mRNA levels of TIPE2, TNF-α, AP-1, IFN-γ and NF-κß in patients with acute ischemic stroke were significantly higher than healthy controls (all P<0.001, respectively). Of note, TIPE2 mRNA showed an increasing trend on a time-dependent manner after the onset of stroke. Furthermore, TIPE2 mRNA was negatively associated with lesion volumes (r=-0.23, P<0.01), NIHSS(r=-0.15, P<0.05), TNF-α(r=-0.33,P<0.001), AP-1(r=-0.28,P<0.001), IFN-γ (r=-0.16, P<0.05) and NF-κß (r=-0.13, P<0.05), but positively associated with IL-6(r=0.14, P<0.05) and IL-10(r=-0.31, P<0.001). Hierarchy cluster analysis showed that TIPE2 mRNA has nearest membership with TNF-α, followed by IL-6, NF-κß, AP-1, IL-10, IL-1ß and IFN-γ. In addition, TIPE2 mRNA in survivals (n=149) was significantly higher than nonsurvivals (n=33) (P<0.001), and showed a great odd ratio (0.52, 95% confidence interval: 0.349-0.760, P<0.001) on 3-month mortality. Conclusions: TIPE2 mRNA contributed to the immune response of stroke and might be a potential biomarker for the mortality of acute ischemic stroke.

In diabetic ketoacidosis brain injury including cerebral oedema and infarction is caused by interleukin-1.

BACKGROUND: Brain injury in diabetic ketoacidosis (DKA) is common but under recognized and affects up to 54% of patients with this complication. It's manifestations include cerebral oedema (CE) and cerebral infarction (CI). The etiology of CE in DKA has up to the present time been uncertain. Practical management had been guided by the assumption that rapid osmotic shifts due to rapid correction of hypovolemia and reduction of plasma glucose could cause a shift of water into the cells. The osmotic effect of glucose can cause inflammation by activation of inflammasomes. Recently it has been recognized that the body is in a pro-inflammatory state during DKA involving interleukin-1 production by inflammasomes. Interleukin-1 has been involved in the pathogenesis of cerebral oedema and CI. HYPOTHESIS: In diabetic ketoacidosis brain injury including cerebral oedema and infarction is caused by interleukin-1. CONFIRMATION OF HYPOTHESIS AND IMPLICATIONS: Inflammasome activity could be quantified in peripheral blood mononuclear cells and in patients with and without clinical and/or subclinical CE and/or stroke or features of cerebral ischemia on MRI. Surrogates of brain injury in peripheral blood like neuron specific enolase could be measured and correlated with inflammasome activity. Interleukin-1 receptor antagonists and inflammasome inhibitors including telmisartan could be assessed in their effect on MRI changes consistent with CE or CI in patients with DKA in randomised placebo-controlled trials.

Lipid lowering drugs and inflammatory changes: an impact on cardiovascular outcomes?

Inflammatory changes are responsible for maintenance of the atherosclerotic process and may underlie some of the most feared vascular complications. Among the multiple mechanisms of inflammation, the arterial deposition of lipids and particularly of cholesterol crystals is the one responsible for the activation of inflammasome NLRP3, followed by the rise of circulating markers, mainly C-reactive protein (CRP). Elevation of lipoproteins, LDL but also VLDL and remnants, associates with increased inflammatory changes and coronary risk. Lipid lowering medications can reduce cholesterolemia and CRP: patients with elevations of both are at greatest cardiovascular (CV) risk and receive maximum benefit from therapy. Evaluation of the major drug series indicates that statins exert the largest LDL and CRP reduction, accompanied by reduced CV events. Other drugs, mainly active on the triglyceride/HDL axis, for example, PPAR agonists, may improve CRP and the lipid pattern, especially in patients with metabolic syndrome. PCSK9 antagonists, the newest most potent medications, do not induce significant changes in inflammatory markers, but patients with the highest baseline CRP levels show the best CV risk reduction. Parallel evaluation of lipids and inflammatory changes clearly indicates a significant link, both guiding to patients at highest risk, and to the best pharmacological approach. Key messages Lipid lowering agents with "pleiotropic" effects provide a more effective approach to CV prevention In CANTOS study, patients achieving on-treatment hsCRP concentrations ≤2 mg/L had a higher benefit in terms of reduction in major CV events The anti-inflammatory activity of PCSK9 antagonists appears to be of a minimal extent.

Dominant role of microglial and macrophage innate immune responses in human ischemic infarcts.

Inflammatory mechanisms, involving granulocytes, T-cells, B-cells, macrophages and activated microglia, have been suggested to play a pathogenic role in experimental models of stroke and may be targets for therapeutic intervention. However, knowledge on the inflammatory response in human stroke lesions is limited. Here, we performed a quantitative study on the inflammatory reaction in human ischemic infarct lesions. We found increased numbers of T-lymphocytes, mainly CD8+ cells, but not of B-lymphocytes. Their number was very low in comparison to that seen in inflammatory diseases of the central nervous system and they did not show signs of activation. Polymorphonuclear leukocytes were present in meninges and less prominently in the perivascular space in early lesions, but their infiltration into the lesioned tissue was sparse with the exception of a single case. Microglia were lost in the necrotic core of fresh lesions, their number was increased in the surrounding penumbra, apparently due to proliferation. Using TMEM119 as a marker for the resident microglia pool, macrophages in lesions were in part derived from the original microglia pool, depending on the lesion stage. Most microglia and macrophages revealed a pro-inflammatory activation pattern, expressing molecules involved in phagocytosis, oxidative injury, antigen presentation and iron metabolism and had partially lost the expression of P2RY12, an antigen expressed on homeostatic ("resting") microglia in rodents. At later lesion stages, the majority of macrophages showed intermediate activation patterns, expressing pro-inflammatory and anti-inflammatory markers. Microglia in the normal white matter of controls and stroke patients were already partly activated toward a pro-inflammatory phenotype. Our data suggest that the direct contribution of lymphocytes and granulocytes to active tissue injury in human ischemic infarct lesions is limited and that stroke therapy that targets pro-inflammatory microglia and macrophage activation may be effective.

Multiple sclerosis: Serum anti-CNS autoantibodies.

BACKGROUND: It is uncertain whether there are autoantibodies detectable by indirect immunofluorescence in the serum of patients with multiple sclerosis (MS). OBJECTIVE: To determine whether there are anti-central nervous system (CNS) autoantibodies detectable by indirect immunofluorescence in the serum of MS patients. METHODS: Sera and in some cases cerebrospinal fluid from 106 patients with multiple sclerosis, 156 patients with other neurological diseases, and 70 healthy control subjects were examined by indirect immunofluorescence using cryostat sections of rat cerebrum fixed by perfusion with paraformaldehyde. RESULTS: Autoantibodies were detected that recognized more than 30 neuronal, glial, and mesodermal structures in 28 of 106 MS cases. Most were also detected in patients with other related and unrelated neurological diseases and several were also found in healthy controls. Novel anti-CNS autoantibodies recognizing particular sets of interneurons were detected in both normal controls and in subjects with CNS diseases. INTERPRETATION: Serum anti-CNS autoantibodies of diverse specificities are common in MS patients. The same anti-CNS autoantibodies are not uncommon in patients with other neurological diseases. The findings provide no support for the proposition that myelin breakdown in MS is caused by exposure of intact myelin sheaths or oligodendrocytes to a pathogenic serum anti-myelin or anti-oligodendrocyte autoantibody.

Efficacy of Urtoxazumab (TMA-15 Humanized Monoclonal Antibody Specific for Shiga Toxin 2) Against Post-Diarrheal Neurological Sequelae Caused by Escherichia coli O157:H7 Infection in the Neonatal Gnotobiotic Piglet Model.

Enterohemorrhagic Escherichia coli (EHEC) is the most common cause of hemorrhagic colitis and hemolytic uremic syndrome in human patients, with brain damage and dysfunction the main cause of acute death. We evaluated the efficacy of urtoxazumab (TMA-15, Teijin Pharma Limited), a humanized monoclonal antibody against Shiga toxin (Stx) 2 for the prevention of brain damage, dysfunction, and death in a piglet EHEC infection model. Forty-five neonatal gnotobiotic piglets were inoculated orally with 3 × 108 colony-forming units of EHEC O157:H7 strain EDL933 (Stx1⁺, Stx2⁺) when 22-24 h old. At 24 h post-inoculation, piglets were intraperitoneally administered placebo or TMA-15 (0.3, 1.0 or 3.0 mg/kg body weight). Compared to placebo (n = 10), TMA-15 (n = 35) yielded a significantly greater probability of survival, length of survival, and weight gain (p <0.05). The efficacy of TMA-15 against brain lesions and death was 62.9% (p = 0.0004) and 71.4% (p = 0.0004), respectively. These results suggest that TMA-15 may potentially prevent or reduce vascular necrosis and infarction of the brain attributable to Stx2 in human patients acutely infected with EHEC. However, we do not infer that TMA-15 treatment will completely protect human patients infected with EHEC O157:H7 strains that produce both Stx1 and Stx2.

Multiplex immunoassay characterization and species comparison of inflammation in acute and non-acute ischemic infarcts in human and mouse brain tissue.

This study provides a parallel characterization of the cytokine and chemokine response to stroke in the human and mouse brain at different stages of infarct resolution. The study goal was to address the hypothesis that chronic inflammation may contribute to stroke-related dementia. We used C57BL/6 and BALB/c mice to control for strain related differences in the mouse immune response. Our data indicate that in both mouse strains, and humans, there is increased granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin-6 (IL-6), interleukin-12 p70 (IL-12p70), interferon gamma-induced protein-10 (IP-10), keratinocyte chemoattractant/interleukin-8 (KC/IL-8), monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1α (MIP-1α), macrophage inflammatory protein-1ß (MIP-1ß), regulated on activation, normal T cell expressed and secreted (RANTES), and Tumor necrosis factor-α (TNF-α) in the infarct core during the acute time period. Nevertheless, correlation and two-way ANOVA analyses reveal that despite this substantial overlap between species, there are still significant differences, particularly in the regulation of granulocyte colony-stimulating factor (G-CSF), which is increased in mice but not in humans. In the weeks after stroke, during the stage of liquefactive necrosis, there is significant resolution of the inflammatory response to stroke within the infarct. However, CD68+ macrophages remain present, and levels of IL-6 and MCP-1 remain chronically elevated in infarcts from both mice and humans. Furthermore, there is a chronic T cell response within the infarct in both species. This response is differentially polarized towards a T helper 1 (Th1) response in C57BL/6 mice, and a T helper 2 (Th2) response in BALB/c mice, suggesting that the chronic inflammatory response to stroke may follow a different trajectory in different patients. To control for the fact that the average age of the patients used in this study was 80 years, they were of both sexes, and many had suffered from multiple strokes, we also present findings that reveal how the chronic inflammatory response to stroke is impacted by age, sex, and multiple strokes in mice. Our data indicate that the chronic cytokine and chemokine response to stroke is not substantially altered in 18-month old compared to 3-month old C57BL/6 mice, although T cell infiltration is attenuated. We found a significant correlation in the chronic cytokine response to stroke in males and females. However, the chronic cytokine response to stroke was mildly exacerbated by a recurrent stroke in both C57BL/6 and BALB/c mice.

Infiltration of invariant natural killer T cells occur and accelerate brain infarction in permanent ischemic stroke in mice.

Invariant natural killer T (iNKT) cells are a unique subset of T cells that have been implicated in inflammation, atopy, autoimmunity, infections, and cancer. Although iNKT cells have been extensively studied over the past decade, its role in the pathogenesis of ischemic brain injury is still largely unknown. In our study, we determined whether iNKT cells infiltration occur in a mouse model of permanent cerebral ischemia. C57BL6/J male mice were treated with either alpha-galactosylceramide (α-GalCer) or vehicle control before undergoing permanent middle cerebral artery occlusion (pMCAO). α-GalCer, a glycolipid antigen, specifically activates iNKT cells by a CD1d-restricted mechanism. Using flow cytometry, 10,000 leukocytes (CD45 high cells) from the ischemic hemisphere and peripheral blood respectively were analyzed to determine the number of NK1.1+CD3+ cells at 3, 12, 24 and 48h post-pMCAO. Cerebral infarct size, brain edema and morphological characteristics were measured at the stipulated time points by 2,3,5-triphenyltetrazolium chloride (TTC) staining, weighing, and H&E staining. The levels of IFN-γ and TNF-α in brain tissue and serum were assessed by immunohistochemistry and ELISA respectively. We found that the number of iNKT cells started increasing from 12h (PB sample) and 24h (ischemic hemisphere sample) respectively in the vehicle treated group. iNKT cells infiltration occurred at an earlier time-point compared in the α-GalCer treated group (T=3H vs T=12H in PB sample; T=12H vs T=24H in ischemic hemisphere sample). Brain water content at 12h and 24h was significantly higher in pMCAO+α-GalCer mice compared to pMCAO+vehicle mice which was in turn higher than mice that underwent sham surgery. Aggravated morphological abnormalities in HE-stained neurons and significantly increased neurons with pyknotic nuclei and cavitation in the ischemic region were observed at 24h in the pMCAO+α-GalCer and pMCAO+vehicle groups. Cerebral infarct volume, neurological deficit Scores and brain edema were significantly increased at 24h in the pMCAO+α-GalCer group compared to pMCAO+vehicle group. In the pMCAO+vehicle group, the serum concentrations of TNF-α and IFN-γ were increased at 12h and 24h post-pMCAO, and remained elevated up to 48h. In mice treated with pMCAO+α-GalCer, TNF-α and IFN-γ were both increased at 12h post-pMCAO, and remained elevated up to 48h. Immunohistochemistry showed that protein expression of TNF-α and IFN-γ in brain tissues was higher in α-GalCer-treated mice. Our results demonstrate that within 48h of focal permanent cerebral ischemia, iNKT cells infiltrate into the brain and contribute to brain infarction.

Relation of antiphospholipid antibodies to postmortem brain infarcts in older people.

BACKGROUND: There are few data on the relationship of antiphospholipid antibodies (aPLs) to pathologically proven brain infarcts. We tested the hypothesis that aPLs are associated with a higher odds of brain infarcts among older, community-dwelling individuals who came to autopsy. METHODS AND RESULTS: Specimens and clinical and pathological data were derived from 607 deceased subjects (mean age at death, 89 years; 66% women) who were participating in 1 of 2 cohort studies of aging (Rush Memory and Aging Project and Religious Orders Study) and had agreed to brain autopsy. Brain infarcts were identified on gross and microscopic examinations, and severity of cerebral vessel disease (atherosclerosis, arteriolosclerosis) was graded. Four clinically used aPLs were measured longitudinally: 3 in serum (anticardiolipin antibodies, ß2-glycoprotein I, and anti-phosphatidyl-serine) and 1 in plasma (lupus anticoagulant). A quarter of subjects (142 of 607, 23%) had at least 1 aPL present at baseline (median time interval from baseline to death, 4.6 years), and three quarters of these subjects had persistently positive measures over time. In a logistic regression analysis, baseline aPL positivity did not increase the odds of brain infarcts (odds ratio=1.08; 95% confidence interval, 0.74-1.58; P=0.19) or of gross or microscopic infarcts separately. Findings were essentially unchanged when considering number of baseline aPLs, aPLs proximate to death, and persistence of aPLs. Associations did not differ among subjects with increased severity of vessel disease. CONCLUSION: Overall, we did not find evidence that aPLs increase the odds of pathological brain infarcts in older people.

Ferumoxytol administration does not alter infarct volume or the inflammatory response to stroke in mice.

Ferumoxytol is an ultrasmall superparamagnetic iron oxide (USPIO) nanoparticle that is FDA-approved as an intravenous iron replacement therapy for the treatment of iron deficiency anemia in patients with chronic kidney disease. Ferumoxytol has also been used as a contrast agent for cerebral blood volume mapping by magnetic resonance imaging (MRI), which suggests it could be used for imaging hemodynamic abnormalities after stroke. However, circulating macrophages can internalize USPIOs, and recent data indicate that the accumulation of iron in macrophages can lead them to adopt the M1 pro-inflammatory phenotype. Therefore, the uptake of intravenously administered iron particles by circulating macrophages that home to the stroke core could potentially alter the inflammatory response to stroke. To test this possibility in vivo we administered a dose of ferumoxytol previously used to obtain cerebral blood volume maps in healthy humans by steady-state susceptibility contrast (SSC) MRI to BALB/cJ mice 48h after stroke and examined cytokine levels, microglial/macrophage activation, and lesion volume in the brain 5 days later. Treatment with ferumoxytol did not lead to any differences in these parameters. These data indicate that the use of ferumoxytol as a contrast agent for brain imaging after stroke does not alter the inflammatory response to stroke in mice, and is therefore unlikely to do so in human subjects.

Inducible nitric oxide synthase in neutrophils and endothelium contributes to ischemic brain injury in mice.

NO produced by inducible NO synthase (iNOS) contributes to ischemic brain injury, but the cell types expressing iNOS and mediating tissue damage have not been elucidated. To examine the relative contribution of iNOS in resident brain cells and peripheral leukocytes infiltrating the ischemic brain, we used bone marrow (BM) chimeric mice in which the middle cerebral artery was occluded and infarct volume was determined 3 d later. iNOS(-/-) mice engrafted with iNOS(+/+) BM exhibited larger infarcts (44 ± 2 mm(3); n = 13; mean ± SE) compared with autologous transplanted iNOS(-/-) mice (24 ± 3 mm(3); n = 10; p < 0.01), implicating blood-borne leukocytes in the damage. Furthermore, iNOS(+/+) mice transplanted with iNOS(-/-) BM had large infarcts (39 ± 6 mm(3); n = 13), similar to those of autologous transplanted iNOS(+/+) mice (39 ± 4 mm(3); n = 14), indicating the resident brain cells also play a role. Flow cytometry and cell sorting revealed that iNOS is highly expressed in neutrophils and endothelium but not microglia. Surprisingly, postischemic iNOS expression was enhanced in the endothelium of iNOS(+/+) mice transplanted with iNOS(-/-) BM and in leukocytes of iNOS(-/-) mice with iNOS(+/+) BM, suggesting that endothelial iNOS suppresses iNOS expression in leukocytes and vice versa. To provide independent evidence that neutrophils mediate brain injury, neutrophils were isolated and transferred to mice 24 h after stroke. Consistent with the result in chimeric mice, transfer of iNOS(+/+), but not iNOS(-/-), neutrophils into iNOS(-/-) mice increased infarct volume. The findings establish that iNOS in both neutrophils and endothelium mediates tissue damage and identify these cell types as putative therapeutic targets for stroke injury.

[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.

Ischemic neurons recruit natural killer cells that accelerate brain infarction.

Brain ischemia and reperfusion activate the immune system. The abrupt development of brain ischemic lesions suggests that innate immune cells may shape the outcome of stroke. Natural killer (NK) cells are innate lymphocytes that can be swiftly mobilized during the earliest phases of immune responses, but their role during stroke remains unknown. Herein, we found that NK cells infiltrated the ischemic lesions of the human brain. In a mouse model of cerebral ischemia, ischemic neuron-derived fractalkine recruited NK cells, which subsequently determined the size of brain lesions in a T and B cell-independent manner. NK cell-mediated exacerbation of brain infarction occurred rapidly after ischemia via the disruption of NK cell tolerance, augmenting local inflammation and neuronal hyperactivity. Therefore, NK cells catalyzed neuronal death in the ischemic brain.