Systemic infection, inflammation and acute ischemic stroke

Responsiveness of primary care services: development of a patient-report measure – qualitative study and initial quantitative pilot testing

Background

Primary care service providers do not always respond to the needs of diverse groups of patients, and so certain patients groups are disadvantaged. General practitioner (GP) practices are increasingly encouraged to be more responsive to patients’ needs in order to address inequalities.

Objectives

(1) Explore the meaning of responsiveness in primary care. (2) Develop a patient-report questionnaire for use as a measure of patient experience of responsiveness by a range of primary care organisations (PCOs). (3) Investigate methods of population mapping available to GP practices.

Design setting

PCOs, including GP practices, walk-in centres and community pharmacies.

Participants

Patients and staff from 12 PCOs in the East Midlands in the development stage, and 15 PCOs across three different regions of England in stage 3.

Interventions

To investigate what responsiveness means, we conducted a literature review and interviews with patients and staff in 12 PCOs. We developed, tested and piloted the use of a questionnaire. We explored approaches for GP practices to understand the diversity of their populations.

Main outcome measures

(1) Definition of primary care responsiveness. (2) Three patient-report questionnaires to provide an assessment of patient experience of GP, pharmacy and walk-in centre responsiveness. (3) Insight into challenges in collecting diversity data in primary care.

Results

The literature covers three overlapping themes of service quality, inequalities and patient involvement. We suggest that responsiveness is achieved through alignment between service delivery and patient needs, involving strategies to improve responsive service delivery, and efforts to manage patient expectations. We identified three components of responsive service delivery: proactive population orientation, reactive population orientation and individual patient orientation. PCOs tend to utilise reactive strategies rather than proactive approaches. Questionnaire development involved efforts to include patients who are ‘seldom heard’. The questionnaire was checked for validity and consistency and is available in three versions (GP, pharmacy, and walk-in centre), and in Easy Read format. We found the questionnaires to be acceptable to patients, and to have content validity. We produced some preliminary evidence of reliability and construct validity. Measuring and improving responsiveness requires PCOs to understand the characteristics of their patient population, but we identified significant barriers and challenges to this.

Conclusions

Responsiveness is a complex concept. It involves alignment between service delivery and the needs of diverse patient groups. Reactive and proactive strategies at individual and population level are required, but PCOs mainly rely on reactive approaches. Being responsive means giving good care equally to all, and some groups may require extra support. What this extra support is will differ in different patient populations, and so knowledge of the practice population is essential. Practices need to be motivated to collect and use diversity data. Future work needed includes further evaluation of the patient-report questionnaires, including Easy Read versions, to provide further evidence of their quality and acceptability; research into how to facilitative the use of patient experience data in primary care; and implementation of strategies to improve responsiveness, and evaluation of effectiveness.

Funding

The National Institute for Health Research Service Delivery and Organisation programme.

Viral pre-challenge increases central nervous system inflammation after intracranial interleukin-1β injection

Introduction

Systemic inflammation has been shown to significantly worsen the outcome of neurological disease. However, after acute injuries to the brain both pre- and post-conditioning with bacterial endotoxin has been shown to reduce leukocyte recruitment to the CNS. Here, we sought to determine whether viral pre-challenge would have an effect on the outcome of acute CNS inflammation that was distinct from endotoxin.

Methods

Animals received a single intracranial microinjection of IL-1β in the presence or absence of a viral pre-challenge 24 hours prior to surgery. Liver and brain tissue were analysed for chemokine expression by qRT-PCR and leukocyte and monocyte infiltration 12 hours, 3 days and 7 days after the IL-1β injection.

Results

Here, a single injection of adenovirus prior to IL-1β injection resulted in adhesion molecule expression, chemokine expression and the recruitment of neutrophils to the injured CNS in significantly higher numbers than in IL-1β injected animals. The distribution and persistence of leukocytes within the CNS was also greater after pre-challenge, with neutrophils being found in both the ipsilateral and contralateral hemispheres. Thus, despite the absence of virus within the CNS, the presence of virus within the periphery was sufficient to exacerbate CNS disease.

Conclusions

These data suggest that the effect of a peripheral inflammatory challenge on the outcome of CNS injury or disease is not generic and will be highly dependent on the nature of the pathogen.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-014-0178-3) contains supplementary material, which is available to authorized users.

Childhood infections and trauma as risk factors for stroke

Stroke is as common as brain tumor in children. The etiology of childhood arterial ischemic stroke (AIS) appears to be multifactorial, resulting from the interaction between genetic predisposition and environmental triggers. The risk factors for AIS in children are markedly different from the atherosclerotic risk factors in adults. Trauma and infections have been identified as associations in previous studies and are exposures of particular interest because of their increased prevalence in the children. The aim of this review article is to provide an overview of the research studies that have addressed the role of infections and trauma in pediatric AIS.

Protective effects of Hericium erinaceus mycelium and its isolated erinacine A against ischemia-injury-induced neuronal cell death via the inhibition of iNOS/p38 MAPK and nitrotyrosine

Hericium erinaceus, an edible mushroom, has been demonstrated to potentiate the effects of numerous biological activities. The aim of this study was to investigate whether H. erinaceus mycelium could act as an anti-inflammatory agent to bring about neuroprotection using a model of global ischemic stroke and the mechanisms involved. Rats were treated with H. erinaceus mycelium and its isolated diterpenoid derivative, erinacine A, after ischemia reperfusion brain injuries caused by the occlusion of the two common carotid arteries. The production of inflammatory cytokines in serum and the infracted volume of the brain were measured. The proteins from the stroke animal model (SAM) were evaluated to determine the effect of H. erinaceus mycelium. H. erinaceus mycelium reduced the total infarcted volumes by 22% and 44% at a concentration of 50 and 300 mg/kg, respectively, compared to the SAM group. The levels of acute inflammatory cytokines, including interleukin-1β, interleukin-6 and tumor necrosis factor á, were all reduced by erinacine A. Levels of nitrotyrosine-containing proteins, phosphorylation of p38 MAPK and CCAAT enhancer-binding protein (C/EBP) and homologous protein (CHOP) expression were attenuated by erinacine A. Moreover, the modulation of ischemia injury factors present in the SAM model by erinacine A seemed to result in the suppression of reactive nitrogen species and the downregulation of inducible NO synthase (iNOS), p38 MAPK and CHOP. These findings confirm the nerve-growth properties of Hericium erinaceus mycelium, which include the prevention of ischemic injury to neurons; this protective effect seems to be involved in the in vivo activity of iNOS, p38 MAPK and CHOP.

Ceftriaxone pretreatment protects rats against cerebral ischemic injury by attenuating microglial activation-induced IL-1β expression

BACKGROUND

Although the neuroprotective effect of ceftriaxone (CTX) has been reported, the underlying mechanisms are still uncertain. In this study, we investigated if rats recover better from CTX pretreatment against cerebral ischemia by inhibiting the inflammatory response.

METHODS

Rats were pretreated with CTX (200 mg/kg, 1/day, i.p.) for 5 d. At 24 h after the end of the last CTX pretreatment, focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 120 min in male Sprague Dawley rats. The neurological deficit scores (NDS) and infarct volumes were evaluated. Microglia cells were observed by immunofluorescence staining and IL-1β was assayed by ELISA and Western Blot.

RESULTS

The results showed that CTX pretreatment improved the neurological deficit scores and decreased the infarct volumes 24 h after reperfusion. The activation of microglia cells was reduced and the expression of IL-1β was partially inhibited 24 h after reperfusion.

CONCLUSION

These findings demonstrate that CTX pretreatment may provide a neuroprotective effect against transient cerebral ischemic injury, partially inhibit in microglial activation and reduce the expression of IL-1β.

Therapeutically targeting neuroinflammation and microglia after acute ischemic stroke

Inflammation has a pivotal role in the pathogenesis of ischemic stroke, and recent studies posit that inflammation acts as a double-edged sword, not only detrimentally augmenting secondary injury, but also potentially promoting recovery. An initial event of inflammation in ischemic stroke is the activation of microglia, leading to production of both pro- and anti-inflammatory mediators acting through multiple receptor signaling pathways. In this review, we discuss the role of microglial mediators in acute ischemic stroke and elaborate on preclinical and clinical studies focused on microglia in stroke models. Understanding how microglia can lead to both pro- and anti-inflammatory responses may be essential to implement therapeutic strategies using immunomodulatory interventions in ischemic stroke.

Association between intercellular adhesion molecule-1 gene K469E polymorphism and the risk of stroke in a Chinese population: a meta-analysis

Several epidemiologic studies have evaluated the association between intercellular adhesion molecule-1 (ICAM-1) gene K469E polymorphism and stroke, but the results were inconsistent. The present meta-analysis was performed to investigate the relationship between K469E polymorphism and stroke in the Chinese population. A comprehensive search for related studies from the electronic databases of PubMed, Embase, Web of Science, CBMdisc and CNKI as well as a manual search of the references of identified articles was performed. Data were extracted to calculate for allelic, additive, dominant and recessive models using pooled odds ratios (ORs) along with 95% confidence intervals (CIs) by Review Manager 5.0 and Stata 11.0. Different effect models, subgroup analysis, sensitivity analysis, publication bias and power calculations were used to improve the comprehensive analysis. Finally, a total of 12 studies containing 1593 cases and 1555 controls were included in the final meta-analysis. No evidence of significant association between ICAM-1 gene K469E polymorphism and stroke was found in all four models (allelic model: OR = 1.07, 95%CI = 0.78-1.47; additive model: OR = 1.21, 95% CI = 0.67-2.16 (EE vs. KK); OR = 1.04, 95%CI = 0.75-1.45 (EK vs. KK); dominant model: OR = 1.07, 95% CI = 0.73-1.56; and recessive model: OR = 1.18, 95% CI = 0.77-1.83, respectively) based on the overall population, as well as subgroup analysis and sensitivity analysis. In conclusion, the present meta-analysis showed no evidence of significant association between ICAM-1 gene K469E polymorphism and stroke in the Chinese population. Nonetheless, this conclusion should be interpreted cautiously due to the low statistical power and considerable heterogeneity. Therefore, larger sample-size studies with homogeneous cases and well-matched controls are needed to further address this correlation.

Correlations of MCP-1 -2518A>G polymorphism and serum levels with cerebral infarction risk: a meta-analysis

This meta-analysis was performed to evaluate the relationships between the monocyte chemoattractant protein-1 (MCP-1) -2518A>G (rs1024611 A>G) polymorphism and its serum levels, and the risk of cerebral infarction. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched for relevant articles published before October 1st, 2013 without language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) or standardized mean difference (SMD) with their 95% confidence intervals (95% CIs) were calculated. Twelve case-control studies that met all the inclusion criteria were included in this meta-analysis. A total of 1272 patients with cerebral infarction and 1210 healthy control subjects were involved in this meta-analysis. Our meta-analysis results reveal that the MCP-1 -2518A>G polymorphism might increase the risk of cerebral infarction (A allele vs. G allele: OR=1.37, 95% CI: 1.18-1.60, p<0.001; GA+AA vs. GG: OR=1.33, 95% CI: 1.09-1.62, p=0.005; respectively). Furthermore, cerebral infarction patients had higher levels of serum MCP-1 than did healthy control subjects (SMD=2.96, 95% CI: 2.00-3.92, p<0.001). Statistical analysis revealed no evidence of publication bias in this meta-analysis (all p>0.05). Our findings indicate that the MCP-1 -2518A>G polymorphism and serum MCP-1 levels may contribute to the development of cerebral infarction. Thus, the MCP-1 -2518A>G polymorphism and serum MCP-1 levels could be potential biomarkers for the early detection of cerebral infarction.

Blood brain barrier and neuroinflammation are critical targets of IGF-1-mediated neuroprotection in stroke for middle-aged female rats

Ischemia-induced cerebral infarction is more severe in older animals as compared to younger animals, and is associated with reduced availability of insulin-like growth factor (IGF)-1. This study determined the effect of post-stroke IGF-1 treatment, and used microRNA profiling to identify mechanisms underlying IGF-1’s neuroprotective actions. Post-stroke ICV administration of IGF-1 to middle-aged female rats reduced infarct volume by 39% when measured 24h later. MicroRNA analyses of ischemic tissue collected at the early post-stroke phase (4h) indicated that 8 out of 168 disease-related miRNA were significantly downregulated by IGF-1. KEGG pathway analysis implicated these miRNA in PI3K-Akt signaling, cell adhesion/ECM receptor pathways and T-and B-cell signaling. Specific components of these pathways were subsequently analyzed in vehicle and IGF-1 treated middle-aged females. Phospho-Akt was reduced by ischemia at 4h, but elevated by IGF-1 treatment at 24h. IGF-1 induced Akt activation was preceded by a reduction of blood brain barrier permeability at 4h post-stroke and global suppression of cytokines including IL-6, IL-10 and TNF-α. A subset of these cytokines including IL-6 was also suppressed by IGF-1 at 24h post-stroke. These data are the first to show that the temporal and mechanistic components of post-stroke IGF-1 treatment in older animals, and that cellular components of the blood brain barrier may serve as critical targets of IGF-1 in the aging brain.

Immune mechanisms in cerebral ischemic tolerance

Stressor-induced tolerance is a central mechanism in the response of bacteria, plants, and animals to potentially harmful environmental challenges. This response is characterized by immediate changes in cellular metabolism and by the delayed transcriptional activation or inhibition of genetic programs that are not generally stressor specific (cross-tolerance). These programs are aimed at countering the deleterious effects of the stressor. While induction of this response (preconditioning) can be established at the cellular level, activation of systemic networks is essential for the protection to occur throughout the organs of the body. This is best signified by the phenomenon of remote ischemic preconditioning, whereby application of ischemic stress to one tissue or organ induces ischemic tolerance (IT) in remote organs through humoral, cellular and neural signaling. The immune system is an essential component in cerebral IT acting simultaneously both as mediator and target. This dichotomy is based on the fact that activation of inflammatory pathways is necessary to establish IT and that IT can be, in part, attributed to a subdued immune activation after index ischemia. Here we describe the components of the immune system required for induction of IT and review the mechanisms by which a reprogrammed immune response contributes to the neuroprotection observed after preconditioning. Learning how local and systemic immune factors participate in endogenous neuroprotection could lead to the development of new stroke therapies.

Increasing emergency room visits for stroke by elevated levels of fine particulate constituents

The associations between fine particulate matter (PM2.5) and stroke remain inconsistent. We conducted a time-series study to evaluate emergency room (ER) visits for ischemic and hemorrhagic strokes in relation to PM2.5 and its constituents. Generalized additive models were used to model the counts of daily ER visits for ischemic and hemorrhagic strokes among patients admitted to the National Taiwan University Hospital from 1 January 2004 to 31 August 2008. Exposure variables included PM2.5 and the four constituents, nitrate, sulfate, organic carbon (OC), and elemental carbon (EC). 12,982 ischemic stroke and 3362 hemorrhagic stroke cases were identified during the study period. For hemorrhagic stroke, the strongest relative risks (RRs) of ER visits were 1.19 [95% confidence interval (CI), 1.07-1.32] and 1.08 (95% CI, 1.02-1.15) for an interquartile range (IQR) increase in 3-day average nitrate and EC. For ischemic stroke, increased RRs of ER visits of 1.21 (95% CI, 1.07-1.36) and 1.18 (95% CI, 1.06-1.31) were observed in the warm season for an IQR increase in 3-day average of OC and EC, respectively. PM2.5 and OC were associated with increased RRs of ER visits for ischemic stroke among patients aged 65 years or older and female patients. In conclusion, PM2.5 constituents, rather than PM2.5 mass, are more closely related to ER visits for hemorrhagic stroke. Both PM2.5 mass and its chemical constituents are associated with ER visits for ischemic stroke in the warm season, among patients older than 65 years, and female patients.

Increased risk of stroke after septicaemia: a population-based longitudinal study in Taiwan

Inflammation and infection have been noted to increase stroke risk. However, the association between septicaemia and increased risk of stroke remains unclear. This population-based cohort study, using a National Health Insurance database, aimed to investigate whether patients with septicaemia are predisposed to increased stroke risk. The study included all patients hospitalised for septicaemia for the first time between 2000 and 2003 without prior stroke. Patients were followed until the end of 2010 to evaluate incidence of stroke. An age-, gender- and co-morbidities-matched cohort without prior stroke served as the control. Cox's proportional hazards regressions were used to assess differences in stroke risk between groups. Based on hazard ratios (HRs), patients with septicaemia had greater stroke risk, especially in the younger age groups (age <45: HR = 4.16, 95% CI: 2.39-7.24, p<0.001; age 45-64: HR = 1.76, 95% CI: 1.41-2.19, p<0.001; age ≥ 65: HR = 1.05, 95% CI: 0.91-1.22, p>0.05). Haemorrhagic stroke was the dominant type (ischaemic stroke: HR = 1.20, 95% CI: 1.06-1.37, p<0.01; haemorrhagic stroke: HR = 1.82, 95% CI: 1.35-2.46, p<0.001) and patients without co-morbidities were at slightly higher risk (without co-morbidities: HR = 1.49, 95% CI: 1.02-2.17, p<0.05; with co-morbidities: HR = 1.24, 95% CI: 1.10-1.41, p<0.001). The impact of septicaemia on stroke risk was highest within 6 months of the event and gradually declined over time. Our results suggest that septicaemia is associated with an increase in stroke risk, which is greatest in haemorrhagic stroke. Closer attention to patients with history of septicaemia may be warranted for stroke preventive measures, especially for younger patients without co-morbidities.

Protective effect of flavonoid-rich extract from Rosa laevigata Michx on cerebral ischemia-reperfusion injury through suppression of apoptosis and inflammation

The neuroprotective effect and mechanism of the flavonoid-rich extract (FRE) from Rosa laevigata Michx fruit on cerebral ischemia-reperfusion (I/R) injury were investigated. The contents of flavonoids, saponins and tannin were determined, and ten chemicals including chlorogenic acid, 4-hydroxy-3-methoxybenzoic acid, apigenin, luteolin, kaempferol, querce-tin, kaempferide-3-O-glucoside, quercetin-3-rhamnoside, rutin and isorhamnetin-3-O-β-rutinoside from the crude extract were separated. Oral administration of FRE obviously improved the survival rate and prevented I/R-induced disability and histological damage. Further works showed that the natural product had excellent antioxidant activity, significantly decreased DNA fragmentation, up-regulated the expression of Bcl-2, and down-regulated the expressions of p53, Apaf1, Fas, FasL, Bax, Bid, cytochrome C and active Caspase-3, -9 and -8. Moreover, the FRE decreased the expressions of NF-κB, iNOS, MMP-9, COX-2, TNF-α, IL-1β, IL-4, IL-6, and down-regulated the levels of p-JNK, p-ERK and p-p38 in MAPK pathways. Therefore, the flavonoid-rich extract from R. laevigata Michx fruit has the potential actions for treatment of ischemic stroke due to its anti-oxidant, anti-apoptosis and anti-inflammatory properties.

Exacerbation of ischemic brain injury in hypercholesterolemic mice is associated with pronounced changes in peripheral and cerebral immune responses

Inflammation contributes to ischemic brain injury. However, translation of experimental findings from animal models into clinical trials is still ineffective, since the majority of human stroke studies mainly focus on acute neuroprotection, thereby neglecting inflammatory mechanisms and inflammation-associated co-morbidity factors such as hypercholesterolemia. Therefore, both wildtype and ApoE(-/-) mice that exhibit increased serum plasma cholesterol levels fed with normal or high cholesterol diet were exposed to transient middle cerebral artery occlusion. Analysis of peripheral immune responses revealed an ischemia-induced acute leukocytosis in the blood, which was accompanied by enhanced myeloid cell and specifically granulocyte cell counts in the spleen and blood of ApoE(-/-) mice fed with Western diet. These cellular immune changes were further associated with increased levels of pro-inflammatory cytokines like IL-6 and TNF-α. Moreover, endogenous stroke-induced endothelial activation as well as CXCL-1 and CXCL-2 expression were increased, thus resulting in accelerated leukocyte, particularly granulocyte accumulation, and enhanced ischemic tissue damage. The latter was revealed by larger infarct volumes and increased local DNA fragmentation in ischemic brains of ApoE(-/-) mice on Western diet. These effects were not observed in wildtype mice on normal or Western diet and in ApoE(-/-) mice on normal diet. Our data demonstrate that the combination of both ApoE knockout and a high cholesterol diet leads to increased ischemia-induced peripheral and cerebral immune responses, which go along with enhanced cerebral tissue injury. Thus, clinically predisposing conditions related to peripheral inflammation such as hypercholesterolemia should be included in up-coming preclinical stroke research.

Interleukin-16 polymorphism is associated with an increased risk of ischemic stroke

Clinical and experimental data have demonstrated that inflammation plays fundamental roles in the pathogenesis of ischemic stroke. Interleukin-16 (IL-16) is identified as a proinflammatory cytokine that is a key element in the ischemic cascade after cerebral ischemia. We aimed to examine the relationship between the IL-16 polymorphisms and the risk of ischemic stroke in a Chinese population. A total of 198 patients with ischemic stroke and 236 controls were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing method. We found that the rs11556218TG genotype and G allele of IL-16 were associated with significantly increased risks of ischemic stroke (TG versus TT, adjusted OR = 1.88; 95% CI, 1.15-3.07; G versus T, adjusted OR = 1.54; 95% CI, 1.05-2.27, resp.). However, there were no significant differences in the genotype and allele frequencies of IL-16 rs4778889 T/C and rs4072111 C/T polymorphisms between the two groups, even after stratification analyses by age, gender, and the presence or absence of hypertension, diabetes mellitus, hypercholesterolemia, and hypertriglyceridemia. These findings indicate that the IL-16 polymorphism may be related to the etiology of ischemic stroke in the Chinese population.

Functional genetic polymorphisms of monocyte chemoattractant protein 1 and C-C chemokine receptor type 2 in ischemic stroke

Recent findings indicated that monocyte chemoattractant protein 1 (MCP1) and its C-C chemokine receptor type 2 (CCR2) play a key role in ischemic stroke (IS) progression. This study was aimed at evaluating the potential association of the MCP1 gene (MCP1) rs1024611 (-2518 A>G) and CCR2 gene (CCR2) rs1799864 (V64I; 190 G>A) functional single nucleotide polymorphisms (SNPs) with IS in the Armenian population. For the purpose of this study, genomic DNA samples of 100 patients with the first-episode IS and 115 healthy subjects (controls) were genotyped for the selected SNPs using a polymerase chain reaction with sequence-specific primers. The results obtained demonstrated that while the CCR2 rs1799864 SNP genotypes were equally distributed among patients and controls, the frequency and carriage rate of the of the MCP1 rs1024611*G minor allele were higher in patients. While a potential association between IS and CCR2 rs1799864 SNP was evaluated for the first time, the latest finding was in agreement with the earlier data reported for some other populations. In summary, this study revealed no association of CCR2 rs1799864 SNP with IS, and a positive association between G minor allele of MCP1 rs1024611 SNP and IS in the Armenian population. Based on the present and earlier reported data, we concluded that the minor G allele of the MCP1 rs1024611 SNP might be considered a risk factor for IS.

Biomarkers of periodontitis and inflammation in ischemic stroke: A case-control study

Periodontitis is a common infectious disease associated with increased risk for ischemic stroke though presently unclear mechanisms. In a case-control study, we investigated salivary levels of four periodontal pathogens, as well as systemic and local inflammatory markers. The population comprised 98 patients with acute ischemic stroke (mean ± SD, 68.2 ± 9.7 yrs; 45.9% women) and 100 healthy controls (69.1 ± 5.2 yrs; 47.0% women). Patients were more often edentulous and had fewer teeth than controls (13.8 ± 10.8 versus 16.6 ± 10.1). After adjusting for stroke risk factors and number of teeth, controls had higher saliva matrix metalloproteinase-8 (MMP-8), myeloperoxidase (MPO), IL-1β, Aggregatibacter actinomycetemcomitans, and serum LPS activity levels. Patients had higher serum MMP-8 and MPO, and they were more often qPCR-positive for A. actinomycetemcomitans (37.9% versus 19.0%) and for ≥3 periodontopathic species combined (50.0% versus 33.0%). We conclude that controls more often had evidence of current periodontal infection with higher periodontal pathogen amount, endotoxemia, local inflammation and tissue destruction. Stroke patients more often had evidence of end-stage periodontitis with edentulism and missing teeth. They were more often carriers of several periodontopathic pathogens in saliva, especially A. actinomycetemcomitans. Additionally, inflammatory burden may contribute to high systemic inflammation associated with elevated stroke susceptibility.

Role of inflammation and its mediators in acute ischemic stroke

Inflammation plays an important role in the pathogenesis of ischemic stroke and other forms of ischemic brain injury. Increasing evidence suggests that inflammatory response is a double-edged sword, as it not only exacerbates secondary brain injury in the acute stage of stroke but also beneficially contributes to brain recovery after stroke. In this article, we provide an overview on the role of inflammation and its mediators in acute ischemic stroke. We discuss various pro-inflammatory and anti-inflammatory responses in different phases after ischemic stroke and the possible reasons for their failures in clinical trials. Undoubtedly, there is still much to be done in order to translate promising pre-clinical findings into clinical practice. A better understanding of the dynamic balance between pro- and anti-inflammatory responses and identifying the discrepancies between pre-clinical studies and clinical trials may serve as a basis for designing effective therapies.

IL-10-producing B-cells limit CNS inflammation and infarct volume in experimental stroke

Clinical stroke induces inflammatory processes leading to cerebral injury. IL-10 expression is elevated during major CNS diseases and limits inflammation in the brain. Recent evidence demonstrated that absence of B-cells led to larger infarct volumes and increased numbers of activated T-cells, monocytes and microglial cells in the brain, thus implicating a regulatory role of B-cell subpopulations in limiting CNS damage from stroke. The aim of this study was to determine whether the IL-10-producing regulatory B-cell subset can limit CNS inflammation and reduce infarct volume following ischemic stroke in B-cell deficient (μMT(-/-)) mice. Five million IL-10-producing B-cells were obtained from IL-10-GFP reporter mice and transferred i.v. to μMT(-/-)mice. After 24 h following this transfer, recipients were subjected to 60 min of middle cerebral artery occlusion (MCAO) followed by 48 h of reperfusion. Compared to vehicle-treated controls, the IL-10(+) B-cell-replenished μMT(-/-)mice had reduced infarct volume and fewer infiltrating activated T-cells and monocytes in the affected brain hemisphere. These effects in CNS were accompanied by significant increases in regulatory T-cells and expression of the co-inhibitory receptor, PD-1, with a significant reduction in the proinflammatory milieu in the periphery. These novel observations provide the first proof of both immunoregulatory and protective functions of IL-10-secreting B-cells in MCAO that potentially could impart significant benefit for stroke patients in the clinic.

Inflammation-induced catabolism of tryptophan and tyrosine in acute ischemic stroke

Whether the inflammatory response that accompanies acute ischemic stroke induces the kynurenine pathway is currently a matter of conjecture. Activation of this pathway may disturb active metabolites. The aim of this study was thus to characterize the catabolism of tryptophan and tyrosine in acute ischemic stroke (AIS) patients, and its association with cytokines, C-reactive protein, and glucose. Serum levels of 5-hydroxytryptamine, tryptophan catabolites, and competing amino acids and significant ratios of these were measured in 45 AIS patients and compared to those of 40 control subjects. Furthermore, associations between the serum levels of these biomarkers and serum levels of cytokines, C-reactive protein, and glucose were determined. Significantly lower levels of tryptophan and tyrosine in the stroke group indicate increased tryptophan and tyrosine oxidation in acute ischemic stroke, while significantly lowered tryptophan index and tyrosine index indicate a reduced capacity for the synthesis of 5-hydroxytryptamine and catecholamines in the brain, respectively. Furthermore, our findings indicate that the proinflammatory response in acute ischemic stroke may be responsible for a reduced capacity for the biosynthesis of brain catecholamines and mediate neurotoxic effects. Meanwhile, the anti-inflammatory IL-10 may exert a neuroprotective effect and prevent the putative reduced capacity for 5-hydroxytryptamine synthesis in the brain. These mechanisms may be involved in several sequelae following stroke, such as cognitive impairment, depression, and fatigue.

Inflammation and adaptive immunity in Parkinson's disease

The immune system is designed to protect the host from infection and injury. However, when an adaptive immune response continues unchecked in the brain, the proinflammatory innate microglial response leads to the accumulation of neurotoxins and eventual neurodegeneration. What drives such responses are misfolded and nitrated proteins. Indeed, the antigen in Parkinson's disease (PD) is an aberrant self-protein, although the adaptive immune responses are remarkably similar in a range of diseases. Ingress of lymphocytes and chronic activation of glial cells directly affect neurodegeneration. With this understanding, new therapies aimed at modulating the immune system's response during PD could lead to decreased neuronal loss and improved clinical outcomes for disease.

IL-1Ra and its delivery strategies: inserting the association in perspective

Interleukin-1 receptor antagonist (IL-1Ra) is a naturally occurring anti-inflammatory antagonist of interleukin-1 family of pro-inflammatory cytokines. The broad spectrum anti-inflammatory effects of IL-1Ra have been investigated against various auto-immune diseases such as diabetes mellitus, rheumatoid arthritis. Despite of its outstanding broad spectrum anti-inflammatory effects, IL-1Ra has short biological half-life (4-6 h) and to cope with this problem, up till now, many delivery strategies have been applied either to extend the half-life and/or prolong the steady-state sustained release of IL-1Ra from its target site. Here in our present paper, we have provided an overview of all approaches attempted to prolong the duration of therapeutic effects of IL-1Ra either by fusing IL-1Ra using fusion protein technology to extend the half-life and/or development of new dosage forms using various biodegradable polymers to prolong its steady-state sustained release at the site of administration. These approaches have been characterized by their intended impact on either in vitro release characteristics and/or pharmacokinetic and pharmacodynamic parameters of IL-1Ra. We have also compared these delivery strategies with each other on the basis of bioactivity of IL-1Ra after fusion with fusion protein partner and/or encapsulation with biodegradable polymer.

Antibody levels to persistent pathogens and incident stroke in Mexican Americans

Background

Persistent pathogens have been proposed as risk factors for stroke; however, the evidence remains inconclusive. Mexican Americans have an increased risk of stroke especially at younger ages, as well as a higher prevalence of infections caused by several persistent pathogens.

Methodology/Principal

Findings Using data from the Sacramento Area Latino Study on Aging (n = 1621), the authors used discrete-time regression to examine associations between stroke risk and (1) immunoglobulin G antibody levels to Helicobacter pylori (H. pylori), Cytomegalovirus, Varicella Zoster Virus, Toxoplasma gondii and Herpes simplex virus 1, and (2) concurrent exposure to several pathogens (pathogen burden), defined as: (a) summed sero-positivity, (b) number of pathogens eliciting high antibody levels, and (c) average antibody level. Models were adjusted for socio-demographics and stroke risk factors. Antibody levels to H. pylori predicted incident stroke in fully adjusted models (Odds Ratio: 1.58; 95% Confidence Interval: 1.09, 2.28). No significant associations were found between stroke risk and antibody levels to the other four pathogens. No associations were found for pathogen burden and incident stroke in fully adjusted models.

Conclusions/Significance

Our results suggest that exposure to H. pylori may be a stroke risk factor in Mexican Americans and may contribute to ethnic differences in stroke risk given the increased prevalence of exposure to H. pylori in this population. Future studies are needed to confirm this association.

Gua Lou Gui Zhi decoction suppresses LPS-induced activation of the TLR4/NF-κB pathway in BV-2 murine microglial cells

Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling-mediated neuroinflammation contributes to secondary brain damage in ischemic stroke; therefore, anti-inflammatory therapy via suppression of the TLR4/NF-κB pathway could be a promising strategy for the treatment of stroke and post-stroke disabilities. Gua Lou Gui Zhi decoction (GLGZD) has long been used in China to clinically treat dysfunction after stroke such as muscular spasticity, but the precise mechanisms are largely unknown. In the present study, we evaluated the anti-inflammatory effect of GLGZD and investigated the underlying molecular mechanisms using lipopolysaccharide (LPS)-stimulated BV-2 microglial cells as an in vitro inflammatory model of neural cells. We found that GLGZD inhibited the inflammatory response in microglial cells as it significantly reduced LPS-induced expression of pro-inflammatory nitric oxide, tumour necrosis factor-α, interleukin (IL)-6 and IL-1β in BV-2 cells, in a dose-dependent manner. In addition, GLGZD treatment significantly decreased the protein expression of TLR4 and myeloid differentiation factor 88, inhibited the phosphorylation of IκB and blocked the nuclear translocation of NF-κB in BV-2 cells, demonstrating its inhibitory effect on the activation of TLR4/NF-κB signaling. Collectively, our findings suggest that inhibition of the inflammatory response via suppression of the TLR4/NF-κB pathway may be one of the mechanisms through which GLGZD ameliorates the damage in ischemic cerebral tissues.

The immune system in stroke: clinical challenges and their translation to experimental research

Stroke represents an unresolved challenge for both developed and developing countries and has a huge socio-economic impact. Although considerable effort has been made to limit stroke incidence and improve outcome, strategies aimed at protecting injured neurons in the brain have all failed. This failure is likely to be due to both the incompleteness of modelling the disease and its causes in experimental research, and also the lack of understanding of how systemic mechanisms lead to an acute cerebrovascular event or contribute to outcome. Inflammation has been implicated in all forms of brain injury and it is now clear that immune mechanisms profoundly influence (and are responsible for the development of) risk and causation of stroke, and the outcome following the onset of cerebral ischemia. Until very recently, systemic inflammatory mechanisms, with respect to common comorbidities in stroke, have largely been ignored in experimental studies. The main aim is therefore to understand interactions between the immune system and brain injury in order to develop novel therapeutic approaches. Recent data from clinical and experimental research clearly show that systemic inflammatory diseases -such as atherosclerosis, obesity, diabetes or infection - similar to stress and advanced age, are associated with dysregulated immune responses which can profoundly contribute to cerebrovascular inflammation and injury in the central nervous system. In this review, we summarize recent advances in the field of inflammation and stroke, focusing on the challenges of translation between pre-clinical and clinical studies, and potential anti-inflammatory/immunomodulatory therapeutic approaches.

Do stroke models model stroke?

Stroke is one of the leading causes of death worldwide and the biggest reason for long-term disability. Basic research has formed the modern understanding of stroke pathophysiology, and has revealed important molecular, cellular and systemic mechanisms. However, despite decades of research, most translational stroke trials that aim to introduce basic research findings into clinical treatment strategies - most notably in the field of neuroprotection - have failed. Among other obstacles, poor methodological and statistical standards, negative publication bias, and incomplete preclinical testing have been proposed as 'translational roadblocks'. In this article, we introduce the models commonly used in preclinical stroke research, discuss some of the causes of failed translational success and review potential remedies. We further introduce the concept of modeling 'care' of stroke patients, because current preclinical research models the disorder but does not model care or state-of-the-art clinical testing. Stringent statistical methods and controlled preclinical trials have been suggested to counteract weaknesses in preclinical research. We conclude that preclinical stroke research requires (1) appropriate modeling of the disorder, (2) appropriate modeling of the care of stroke patients and (3) an approach to preclinical testing that is similar to clinical testing, including Phase 3 randomized controlled preclinical trials as necessary additional steps before new therapies enter clinical testing.

Effect of IMOD™ on the inflammatory process after acute ischemic stroke: a randomized clinical trial

Background and purpose of the study

Considering the role of inflammation in acute cerebrovascular accidents, anti-inflammatory treatment has been considered as an option in cerebrovascular diseases. Regarding the properties of Setarud (IMOD™) in immune regulation, the aim of the present study was to evaluate the role of this medication in treating patients with acute ischemic stroke.

Methods

In this randomized clinical trial, 99 patients with their first ever acute ischemic stroke were divided into two groups of IMOD™ (n = 49) and control (n = 50). The control group underwent routine treatment and the intervention group underwent routine treatment plus daily intermittent infusion of IMOD™ (250mg on the first day and then 375mg into DW5% serum during a 30-minute period for 7 days). The serum levels of inflammatory markers were evaluated on the first day (baseline) and on 4th and 7th days. Data were analyzed and the results were compared.

Results and major conclusion

58 males (58.6%) and 41 females (41.4%) with a mean age of 67.00 ± 8.82 years, who had their first ever stroke attack, were enrolled in this trial. Treatment with IMOD™ showed a decreasing trend in IL-6 levels compared to the control group (p = 0.04). In addition, the treatment resulted in the control of increasing serum levels of hsCRP after 7 days compared to the control group (p = 0.02). There was an insignificant decrease in TNF-α and IL-1 levels in the IMOD™ group. Considering the prominent role of inflammation after an ischemic cerebral damage, it appears that treatment with IMOD™ improves the inflammatory profile. Therefore, IMOD™ (Setarud) might be considered as a therapeutic option in the acute ischemic stroke. However, future studies are necessary on its long-term results and clinical efficacy.

G protein-coupled receptor kinase 2 and group I metabotropic glutamate receptors mediate inflammation-induced sensitization to excitotoxic neurodegeneration

OBJECTIVE

The concept of inflammation-induced sensitization is emerging in the field of perinatal brain injury, stroke, Alzheimer disease, and multiple sclerosis. However, mechanisms underpinning this process remain unidentified.

METHODS

We combined in vivo systemic lipopolysaccharide-induced or interleukin (IL)-1β-induced sensitization of neonatal and adult rodent cortical neurons to excitotoxic neurodegeneration with in vitro IL-1β sensitization of human and rodent neurons to excitotoxic neurodegeneration. Within these inflammation-induced sensitization models, we assessed metabotropic glutamate receptors (mGluR) signaling and regulation.

RESULTS

We demonstrate for the first time that group I mGluRs mediate inflammation-induced sensitization to neuronal excitotoxicity in neonatal and adult neurons across species. Inflammation-induced G protein-coupled receptor kinase 2 (GRK2) downregulation and genetic deletion of GRK2 mimicked the sensitizing effect of inflammation on excitotoxic neurodegeneration. Thus, we identify GRK2 as a potential molecular link between inflammation and mGluR-mediated sensitization.

INTERPRETATION

Collectively, our findings indicate that inflammation-induced sensitization is universal across species and ages and that group I mGluRs and GRK2 represent new avenues for neuroprotection in perinatal and adult neurological disorders.

Long-term survival of ischemic cerebrovascular disease in the acute inflammatory stroke study, a hospital-based cohort described by TOAST and ASCO

BACKGROUND

Ischemic cerebrovascular disease (ICVD) comprises multiple etiological phenotypes that share common clinical characteristics. Etiological classification of patients with ICVD is of major clinical interest to achieve optimal medical treatment and predict prognosis. The TOAST classification system has been widely used to describe stroke etiology but provides restricted phenotypic homogeneity within groups. The ASCO classification system has introduced a new approach in phenotypic classification, and aims to describe clinical characteristics without merging concurrent comorbidities. Inflammatory processes have been suggested to mediate stroke etiology and pathology. The Acute Inflammatory Stroke Study (AISS), a hospital-based cohort, is here introduced and described by TOAST and ASCO classification systems. The aim of this first analysis of AISS was to investigate long-term mortality in relation to ischemic stroke subtypes, and clinical and biochemical markers.

METHODS

AISS consecutively follows patients on 6 occasions up to 1 year after stroke onset. Complete workup according to ASCO comprised CT or MRI of the head, ECG, duplex of the extracranial arteries or CT/MR angiography and ultrasound of the heart. Level 2 evidence was required in each domain to obtain a comparable system to TOAST (ASCO2). Clinical and biochemical characteristics and mortality rates were documented and compared by the two classification systems.

RESULTS

Of 142 patients consecutively evaluated and recruited in the study, a total of 101 ICVD patients (ischemic stroke, n = 84; transient ischemic attack, n = 17) were included in the final analysis. Agreement between ASCO2 and TOAST was very good. During the mean observation period of 28 months, 26 patients died. The 1- and 4-year mortality rates were 0 and 4% for large artery atherosclerosis (LAA); 23 and 36% for cardioembolism (CE); 0% for small artery occlusion (SAO); 63 and 100% for the subtype with unknown etiology due to incomplete workup (Unknown), and 12 and 29% for the cryptogenic subtype. As for the ASCO2 groups, the 1- and 4-year mortality rates were 0 and 6% in LAA, 25 and 36% in CE, 0% in SAO, 0 and 14% in LAA + CE, 0% in SAO + CE, 16 and 36% in the subgroup with undetermined etiology despite complete workup, and 56 and 100% in Unknown. Regression analysis showed that age, white blood cell count, fibrinogen and bilirubin, but not etiological subgroup, were independent predictors of mortality.

CONCLUSION

Our findings indicate that clinical and biochemical markers may differentiate phenotypically homogeneous etiological subtypes and predict long-term mortality. Further studies with larger patient numbers are needed to investigate possible causative mechanisms.

Hospitalized osteoporotic vertebral fracture increases the risk of stroke: a population-based cohort study

The association between osteoporosis and cardiovascular diseases has been demonstrated. Higher cardiovascular risk has also been correlated with vertebral fractures. However, the association between osteoporotic vertebral fracture and the possibly higher risk of stroke remains uncertain. This study aimed to evaluate the incidence, risk, and type of stroke in patients with osteoporotic vertebral fracture. Patients with osteoporotic vertebral fracture were identified (n = 380) and 10 age- and sex-matched controls per case (comparison group, n = 3795) were chosen from a nationwide representative cohort of 999,997 people from 1998 to 2005. Both groups were followed-up for stroke events for 3 years, matched by propensity scores with adjustments for covariates such as comorbidities (ie, hypertension, diabetes, arrhythmia, or coronary heart diseases) and exposure to medications (ie, aspirin, lipid lowering drug, or nitrates), and assessed by Kaplan-Meier and Cox regression analyses. The incidence rate of stroke in the osteoporotic vertebral fracture group (37.5 per 1000 person-years; 95% confidence interval [CI], 27.5-51.2) was significantly higher than in the comparison group (14.0 per 1000 person-years; 95% CI, 12.0-16.4, p < 0.001). Stroke was more likely to occur in the osteoporotic vertebral fracture patients than in the normal controls (crude hazard ratio [HR] 2.68, 95% CI 1.89-3.79, p < 0.001; adjusted HR 2.71, 95% CI 1.90-3.86, p < 0.001). In conclusion, patients with osteoporotic vertebral fracture have a higher risk of stroke (ie, both ischemic and hemorrhagic) and require stroke prevention strategies.

Why the term neonatal encephalopathy should be preferred over neonatal hypoxic-ischemic encephalopathy

The unresponsiveness of the full-term newborn is sometimes attributed to asphyxia, even when no severe physiologic disturbance occurred during labor and delivery. The controversy about whether to use the name "hypoxic-ischemic encephalopathy" or "newborn encephalopathy" has recently flared in publications directed toward pediatricians and neurologists. In this clinic opinion piece, I discuss the importance to obstetricians of this decision and explain why "newborn encephalopathy" should be the default term.

Immunological biomarkers improve the accuracy of clinical risk models of infection in the acute phase of ischemic stroke

Infection is an independent risk factor for adverse outcome in stroke patients. The risk of developing an infection in this setting is partly related to a stroke-induced immunodepression, in which a shift to a predominant Th2 (immunosuppressive) phenotype has been postulated to play a major role. Our aim was to study whether clinical variables or changes in plasma cytokine expression can predict poststroke infections.

PATIENTS AND METHODS

Medical records of 92 stroke patients were reviewed, and the baseline concentration of cytokines from the Th1/Th2 system was determined. Clinical and serological predictors of incident infections and their prognostic significance were sought by means of univariate and multivariate analysis, and two predictive models for developing an infection were constructed by combining independent predictors (strictly clinical in one, and both clinical and serological in the other) for this outcome. The improvement conferred by the addition of immunological markers to the clinical model was assessed by comparing their respective ROC curves and by improvement (Net Reclassification Index and Integrated Discriminator Improvement) analysis.

RESULTS

Nineteen patients (20.7% of the study sample) developed an infection. Ongoing antiplatelet therapy at symptom onset (OR 0.02, 95% CI 0.001-0.23, p = 0.001), diabetes mellitus (OR 9.96, 95% CI 1.32-75.29, p = 0.03), IL-13 level <33 pg/ml (OR 84.16, 95% CI 2.53-2795.18, p = 0.01) and interferon-γ level >8.4 pg/ml (OR 60.17, 95% CI 1.78-2037.23, p = 0.02) were independently associated with the development of infections during hospital admission. The combined regression model predicted infection with an accuracy of 93.4%, an improvement in the predictive capacity of 17% (p < 0.001). Infection was associated with a worse neurological status at hospital discharge (median NIHSS score 11 (6-18) vs. 4 (1-11.5), p = 0.014).

CONCLUSIONS

This study shows that bloodstream biomarkers are useful to improve the accuracy of clinical prognostic models for infection in the acute phase of stroke. The clinical predictors of infection in the acute phase of stroke are relatively well established in the medical literature, but further research to identify the optimal combination of biomarkers (possibly inflammatory and stress markers) to be included in a clinically useful model is needed. Such a model could be subsequently used in clinical trials to assess the effect of prophylactic and/or early antibiotic therapy in this setting, a currently controversial issue in this field.

Revisiting the timing hypothesis: biomarkers that define the therapeutic window of estrogen for stroke

Significantly extended life expectancy coupled with contemporary sedentary lifestyles and poor nutrition has created a global epidemic of cardiovascular disease and stroke. For women, this issue is complicated by the discrepant outcomes of hormone therapy (HT) for stroke incidence and severity as well as the therapeutic complications for stroke associated with advancing age. Here we propose that the impact of estrogen therapy cannot be considered in isolation, but should include age-related changes in endocrine, immune, and nucleic acid mediators that collaborate with estrogen to produce neuroprotective effects commonly seen in younger, healthier demographics. Due to their role as modulators of ischemic cell death, the post-stroke inflammatory response, and neuronal survival and regeneration, this review proposes that Insulin-like Growth Factor (IGF)-1, Vitamin D, and discrete members of the family of non-coding RNA peptides called microRNAs (miRNAs) may be crucial biochemical markers that help determine the neuroprotective "window" of HT. Specifically, IGF-1 confers neuroprotection in concert with, and independently of, estrogen and failure of the insulin/IGF-1 axis is associated with metabolic disturbances that increase the risk for stroke. Vitamin D and miRNAs regulate and complement IGF-1 mediated function and neuroprotective efficacy via modulation of IGF-1 availability and neural stem cell and immune cell proliferation, differentiation and secretions. Together, age-related decline of these factors differentially affects stroke risk, severity, and outcome, and may provide a novel therapeutic adjunct to traditional HT practices.

Systemic LPS induces spinal inflammatory gene expression and impairs phrenic long-term facilitation following acute intermittent hypoxia

Although systemic inflammation occurs in most pathological conditions that challenge the neural control of breathing, little is known concerning the impact of inflammation on respiratory motor plasticity. Here, we tested the hypothesis that low-grade systemic inflammation induced by lipopolysaccharide (LPS, 100 μg/kg ip; 3 and 24 h postinjection) elicits spinal inflammatory gene expression and attenuates a form of spinal, respiratory motor plasticity: phrenic long-term facilitation (pLTF) induced by acute intermittent hypoxia (AIH; 3, 5 min hypoxic episodes, 5 min intervals). pLTF was abolished 3 h (vehicle control: 67.1 ± 27.9% baseline; LPS: 3.7 ± 4.2%) and 24 h post-LPS injection (vehicle: 58.3 ± 17.1% baseline; LPS: 3.5 ± 4.3%). Pretreatment with the nonsteroidal anti-inflammatory drug ketoprofen (12.5 mg/kg ip) restored pLTF 24 h post-LPS (55.1 ± 12.3%). LPS increased inflammatory gene expression in the spleen and cervical spinal cord (homogenates and isolated microglia) 3 h postinjection; however, all molecules assessed had returned to baseline by 24 h postinjection. At 3 h post-LPS, cervical spinal iNOS and COX-2 mRNA were differentially increased in microglia and homogenates, suggesting differential contributions from spinal cells. Thus LPS-induced systemic inflammation impairs AIH-induced pLTF, even after measured inflammatory genes returned to normal. Since ketoprofen restores pLTF even without detectable inflammatory gene expression, "downstream" inflammatory molecules most likely impair pLTF. These findings have important implications for many disease states where acute systemic inflammation may undermine the capacity for compensatory respiratory plasticity.

Cytotoxic function of CD8+ T lymphocytes isolated from patients with acute severe cerebral infarction: an assessment of stroke-induced immunosuppression

Background

There is increasing evidence on complex interaction between the nervous and immune systems in patients with cerebral infarction. This study was conducted to evaluate cytotoxic function of CD8⁺ T lymphocytes isolated from patients with acute severe cerebral infarction. In order to determine role of immune system in stroke, peripheral blood mononuclear cells (PBMCs) were taken and cytotoxic function of CD8⁺ T lymphocytes were induced by virus peptides and cells were analyzed on a four-color flow cytometer. Expression of CD107a, intracellular expression of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α), and cell proliferation assay were analyzed by using carboxyl fluorescein diacetate succinimidyl ester (CFSE).

Results

A total of 30 patients with cerebral infarction and 30 healthy volunteers with an average age 57 (range, 49 to 71) years, were evaluated. The PBMCs were separated from blood samples of both, patients with cerebral infarction 6 hours after onset of stroke and healthy volunteers. After stimulation with virus peptides, CD107a expression and intracellular production of IFN-γ and TNF-α was decreased in patients with cerebral infarction as compared to healthy volunteers (p < 0.01). Degranulation analysis reported decreased expression of CD107a + in patient group as compared to healthy group, p <0.01. A mild decrease in intracellular expression of IFN-γ and TNF-α was also shown in patients without stimulation of virus peptides (p < 0.05). However, proliferation of CD8+ T lymphocytes in patients with acute severe cerebral infarction was not decreased.

Conclusions

The study results indicated that cytotoxic function of CD8+ T lymphocytes were suppressed in patients with acute severe cerebral infarction. This could possibly be associated with complicated infectious diseases and neuroprotective mechanism.

Agricultural exposures and stroke mortality in the Agricultural Health Study

Exposures associated with common agricultural activities may increase risk of stroke. The authors evaluated associations between self-reported agricultural activities including pesticide use and handling of crops and stroke mortality among 51,603 male pesticide applicators enrolled in the Agricultural Health Study (AHS). Vital status was obtained through 2008. Stroke mortality was defined by underlying or contributing cause of death (ICD-9 430-438, ICD-10 I60-I69). Information regarding lifetime pesticide use, working with crops or animals, engagement in other agricultural activities, and potential confounders was self-reported at enrollment. Cox proportional hazards models, with age as the time scale, were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) adjusted for state of residence, smoking status, and alcohol consumption. Median follow-up time was 13 yr, during which 308 stroke deaths occurred. No measure of overall or specific pesticide use was positively associated with mortality due to stroke. Stroke mortality was inversely associated with handling hay, grain, or silage at least once each year as reported at enrollment (HR: 0.75; 95% CI: 0.58, 0.98). There was no evidence of an association between pesticide use and stroke mortality. The inverse association between handling of hays and grains and stroke mortality may be due to (1) those engaging in such activities being healthier than those who did not or (2) exposure to some biological agent present in hays and grains. Further investigation of incident stroke, rather than stroke mortality, as well as stroke subtypes, is needed to determine the full role of agricultural exposures and stroke.

Interleukin-1 receptor antagonist is beneficial after subarachnoid haemorrhage in rat by blocking haem-driven inflammatory pathology

Subarachnoid haemorrhage (SAH) is a major contributor to the burden of stroke on society. Treatment options are limited and animal models of SAH do not always mimic key pathophysiological hallmarks of the disease, thus hindering development of new therapeutics. Inflammation is strongly associated with brain injury after SAH in animals and patients, and inhibition of the pro-inflammatory cytokine interleukin-1 (IL-1) represents a possible therapeutic target. Here we report that a rupture of the middle cerebral artery in the rat produces heterogeneous infarct patterns similar to those observed in human SAH. Administration of the IL-1 receptor antagonist (IL-1Ra) reduced blood-brain barrier breakdown, and the extent of breakdown correlated with brain injury. After SAH, haem oxygenase-1 (HO-1) was strongly expressed around the bleed site and in the cortex and striatum, indicating the presence of free haem, a breakdown product of haemoglobin. HO-1 expression was also found in the same regions as microglial/macrophage expression of IL-1α. The direct effect of haem on IL-1α expression was confirmed in vitro using organotypic slice culture (OSC). Haem-induced cell death was dependent on IL-1 signalling, with IL-1Ra completely blocking cellular injury. Furthermore, stimulation of mouse primary mixed glial cells with haem induced the release of IL-1α, but not IL-1β. Thus, we suggest that haem, released from lysed red blood cells (RBCs) in the subarachnoid space, acts as a danger-associated molecular pattern (DAMP) driving IL-1-dependent inflammation. These data provide new insights into inflammation after SAH-induced brain injury and suggest IL-1Ra as a candidate therapeutic for the disease.

Systemic immune activation shapes stroke outcome

Stroke is a major cause of morbidity and mortality, and activation of the immune system can impact on stroke outcome. Although the majority of research has focused on the role of the immune system after stroke there is increasing evidence to suggest that inflammation and immune activation prior to brain injury can influence stroke risk and outcome. With the high prevalence of co-morbidities in the Western world such as obesity, hypertension and diabetes, pre-existing chronic 'low-grade' systemic inflammation has become a customary characteristic of stroke pathophysiology that needs to be considered in the search for new therapies. The importance of the immune system in stroke has been demonstrated in a number of ways, both experimentally and in the clinical setting. This review will focus on the effect of immune activation arising from systemic inflammatory conditions and infection, how it affects the incidence and outcomes of stroke, and the possible underlying mechanisms involved. This article is part of a Special Issue entitled 'Neuroinflammation in neurodegeneration and neurodysfunction'.

Inflammation as a predictor for delayed cerebral ischemia after aneurysmal subarachnoid haemorrhage

BACKGROUND

The mechanism of development of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) is poorly understood. Inflammatory processes are implicated in the development of ischemic stroke and may also predispose to the development of DCI following SAH. The objective of this study was to test whether concentrations of circulating inflammatory markers (C-reactive protein (CRP), interleukin-6 (IL-6) and interleukin 1 receptor antagonist (IL-1Ra)) were predictive for DCI following SAH. Secondary analyses considered white cell count (WCC) and erythrocyte sedimentation rate (ESR).

METHODS

This was a single-center case-control study nested within a prospective cohort. Plasma inflammatory markers were measured in patients up to 15 days after SAH (initial, peak, average, final and rate of change to final). Cases were defined as those developing DCI. Inflammatory markers were compared between cases and randomly selected matched controls.

RESULTS

Among the 179 participants there were 46 cases of DCI (26%). In primary analyses the rate of change of IL-6 was associated with DCI (OR 2.3 (95% CI 1.1 to 5.0); p=0.03). The final value and rate of change of WCC were associated with DCI (OR 1.2 (95% CI 1.0 to 1.3) and OR 1.3 (95% CI 1.0 to 1.6), respectively). High values of ESR were associated with DCI (OR 2.4 (95% CI 1.3 to 4.6) initial; OR 2.3 (95% CI 1.3 to 4.2) average; OR 2.1 (95% CI 1.1 to 3.9) peak; and OR 2.0 (95% CI 1.2 to 3.3) final value).

CONCLUSIONS

Leucocytosis and change in IL-6 prior to DCI reflect impending cerebral ischemia. The time-independent association of ESR with DCI after SAH may identify this as a risk factor. These data suggest that systemic inflammatory mechanisms may increase the susceptibility to the development of DCI after SAH.

Inflammatory cytokines in experimental and human stroke

Inflammation is a hallmark of stroke pathology. The cytokines, tumor necrosis factor (TNF), interleukin (IL)-1, and IL-6, modulate tissue injury in experimental stroke and are therefore potential targets in future stroke therapy. The effect of these cytokines on infarct evolution depends on their availability in the ischemic penumbra in the early phase after stroke onset, corresponding to the therapeutic window (<4.5 hours), which is similar in human and experimental stroke. This review summarizes a large body of literature on the spatiotemporal and cellular production of TNF, IL-1, and IL-6, focusing on the early phase in experimental and human stroke. We also review studies of cytokines in blood and cerebrospinal fluid in stroke. Tumor necrosis factor and IL-1 are upregulated early in peri-infarct microglia. Newer literature suggests that IL-6 is produced by microglia, in addition to neurons. Tumor necrosis factor- and IL-1-producing macrophages infiltrate the infarct and peri-infarct with a delay. This information is discussed in the context of suggestions that neuronal sensitivity to ischemia may be modulated by cytokines. The fact that TNF and IL-1, and suppossedly also IL-6, are produced by microglia within the therapeutic window place these cells centrally in potential future stroke therapy.

Delayed administration of interleukin-1 receptor antagonist reduces ischemic brain damage and inflammation in comorbid rats

Many neuroprotective agents have been effective in experimental stroke, yet few have translated into clinical application. One reason for this may be failure to consider clinical comorbidities/risk factors in experimental models. We have shown that a naturally occurring interleukin-1 receptor antagonist (IL-1Ra) is protective against ischemic brain damage in healthy animals. However, protective effects of IL-1Ra have not been determined in comorbid animals. Thus, we tested whether IL-1Ra protects against brain injury induced by experimental ischemia in aged JCR-LA (corpulent) rats, which have clinically relevant risk factors. Male, aged, lean, and corpulent rats exposed to transient (90 minutes) occlusion of the middle cerebral artery (tMCAO) were administered two doses of IL-1Ra (25 mg/kg, subcutaneously) during reperfusion. Brain injury and neuroinflammatory changes were assessed 24 hours after tMCAO. Our results show that IL-1Ra administered at reperfusion significantly reduced infarct volume measured by magnetic resonance imaging (50%, primary outcome) and blood-brain barrier disruption in these comorbid animals. Interleukin-1Ra also reduced microglial activation, neutrophil infiltration, and cytokines levels in the brain. These data are the first to indicate that IL-1Ra protects against ischemic brain injury when administered via a clinically relevant route and time window in animals with multiple risk factors for stroke.

A pentapeptide monocyte locomotion inhibitory factor protects brain ischemia injury by targeting the eEF1A1/endothelial nitric oxide synthase pathway

BACKGROUND AND PURPOSE

Ischemic stroke is a major cause of death worldwide but lacks viable treatment or treatment targets. Monocyte locomotion inhibitory factor (MLIF) is a small heat-stable pentapeptide produced by Entamoeba histolytica in axenic culture, which is supposed to protect the brain from ischemic injury; the mechanism, however, remains unknown. In this study, we further investigated the mechanism underlying the protective role of MLIF in brain ischemia.

METHODS

A middle cerebral artery occlusion model in rats was used for detecting the effect of MLIF in the brain ischemia in vivo. To identify targets of MLIF in brain endothelial cells, we performed immunoprecipitation of biotin-conjugated MLIF and mass spectrometry.

RESULTS

MLIF can protect the brain from ischemic injury in vivo, yielding decreased ischemic volume, prolonged survival, and improved neurological outcome. In vitro studies showed that MLIF displayed protective effects through inhibition of expression of pathological inflammatory adhesion molecules and enhancing endothelial nitric oxide synthase expression and nitric oxide release in the cerebrovascular endothelium. The target screening experiments demonstrated binding of MLIF to the ribosomal protein translation elongation factor eEF1A1. MLIF enhanced endothelial nitric oxide synthase expression through stabilization of endothelial nitric oxide synthase mRNA, and eEF1A1 was shown to be necessary for this enhanced expression. Knockdown of eEF1A1 or inhibition of endothelial nitric oxide synthase attenuated MLIF-mediated inhibition of adhesion molecule expression.

CONCLUSIONS

In this study, we identified a new potential pharmacologically targetable mechanism underlying MLIF's protective effects in brain ischemia through the eEF1A1/endothelial nitric oxide synthase pathway.

From hypertension to stroke: mechanisms and potential prevention strategies

Stroke is a major cause of disability and death worldwide. Prevention aimed at risk factors of stroke is the most effective strategy to curb the stroke pandemic. Hypertension is one of the most important risk factors for stroke. Despite the substantial evidence of the benefits of lowering blood pressure, conventional treatment does not normalize the burden of major cardiovascular events in patients with hypertension. Fully understanding the factors involved in the hypertension-induced stroke helps to develop new strategies for stroke prevention. Antihypertensive therapies selected should have positive blood pressure-independent effects on stroke risk. This review summarizes the factors involved in the hypertension-induced stroke, such as oxidative stress, inflammation, and arterial baroreflex dysfunction, and potential strategies for its prevention, therefore, provides clues for clinicians.

Neutrophil cerebrovascular transmigration triggers rapid neurotoxicity through release of proteases associated with decondensed DNA

Cerebrovascular inflammation contributes to diverse CNS disorders through mechanisms that are incompletely understood. The recruitment of neutrophils to the brain can contribute to neurotoxicity, particularly during acute brain injuries, such as cerebral ischemia, trauma, and seizures. However, the regulatory and effector mechanisms that underlie neutrophil-mediated neurotoxicity are poorly understood. In this study, we show that mouse neutrophils are not inherently toxic to neurons but that transendothelial migration across IL-1-stimulated brain endothelium triggers neutrophils to acquire a neurotoxic phenotype that causes the rapid death of cultured neurons. Neurotoxicity was induced by the addition of transmigrated neutrophils or conditioned medium, taken from transmigrated neutrophils, to neurons and was partially mediated by excitotoxic mechanisms and soluble proteins. Transmigrated neutrophils also released decondensed DNA associated with proteases, which are known as neutrophil extracellular traps. The blockade of histone-DNA complexes attenuated transmigrated neutrophil-induced neuronal death, whereas the inhibition of key neutrophil proteases in the presence of transmigrated neutrophils rescued neuronal viability. We also show that neutrophil recruitment in the brain is IL-1 dependent, and release of proteases and decondensed DNA from recruited neutrophils in the brain occurs in several in vivo experimental models of neuroinflammation. These data reveal new regulatory and effector mechanisms of neutrophil-mediated neurotoxicity (i.e., the release of proteases and decondensed DNA triggered by phenotypic transformation during cerebrovascular transmigration). Such mechanisms have important implications for neuroinflammatory disorders, notably in the development of antileukocyte therapies.

Genetic variation within the interleukin-1 gene cluster and ischemic stroke

BACKGROUND AND PURPOSE

Evidence is emerging that inflammation plays a key role in the pathophysiology of ischemic stroke (IS). The aim of this study was to investigate whether genetic variation in the interleukin-1α, interleukin-1β, and interleukin-1 receptor antagonist genes (IL1A, IL1B, and IL1RN) is associated with IS and/or any etiologic subtype of IS.

METHODS

Twelve tagSNPs were analyzed in the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), which comprises 844 patients with IS and 668 control subjects. IS subtypes were defined according to the Trial of Org 10172 in Acute Stroke Treatment criteria in SAHLSIS. The Lund Stroke Register and the Malmö Diet and Cancer study were used as a replication sample for overall IS (in total 3145 patients and 1793 control subjects).

RESULTS

The single nucleotide polymorphism rs380092 in IL1RN showed an association with overall IS in SAHLSIS (OR, 1.21; 95% CI, 1.02-1.43; P=0.03), which was replicated in the Lund Stroke Register and the Malmö Diet and Cancer study sample. An association was also detected in all samples combined (OR, 1.12; 95% CI, 1.04-1.21; P=0.03). Three single nucleotide polymorphisms in IL1RN (including rs380092) were nominally associated with the subtype of cryptogenic stroke in SAHLSIS, but the statistical significance did not remain after correction for multiple testing. Furthermore, increased plasma levels of interleukin-1 receptor antagonist were observed in the subtype of cryptogenic stroke compared with controls.

CONCLUSIONS

This comprehensive study, based on a tagSNP approach and replication, presents support for the role of IL1RN in overall IS.