Interleukin-18 in acute ischaemic stroke patients

Targeting pyroptosis to treat ischemic stroke: From molecular pathways to treatment strategy

Ischemic stroke is the primary reason for human disability and death, but the available treatment options are limited. Hence, it is imperative to explore novel and efficient therapies. In recent years, pyroptosis (a pro-inflammatory cell death characterized by inflammation) has emerged as an important pathological mechanism in ischemic stroke that can cause cell death through plasma membrane rupture and release of inflammatory cytokines. Pyroptosis is closely associated with inflammation, which exacerbates the inflammatory response in ischemic stroke. The level of inflammasomes, GSDMD, Caspases, and inflammatory factors is increased after ischemic stroke, exacerbating brain injury by mediating pyroptosis. Hence, inhibition of pyroptosis can be a therapeutic strategy for ischemic stroke. In this review, we have summarized the relationship between pyroptosis and ischemic stroke, as well as a series of treatments to attenuate pyroptosis, intending to provide insights for new therapeutic targets on ischemic stroke.

Inflammation and the Link to Vascular Brain Health: Timing Is Brain

Inflammation and its myriad pathways are now recognized to play both causal and consequential roles in vascular brain health. From acting as a trigger for vascular brain injury, as evidenced by the coronavirus disease 2019 (COVID-19) pandemic, to steadily increasing the risk for chronic cerebrovascular disease, distinct inflammatory cascades play differential roles in varying states of cerebrovascular injury. New evidence is regularly emerging that characterizes the role of specific inflammatory pathways in these varying states including those at risk for stroke and chronic cerebrovascular injury as well as during the acute, subacute, and repair phases of stroke. Here, we aim to highlight recent basic science and clinical evidence for many distinct inflammatory cascades active in these varying states of cerebrovascular injury. The role of cerebrovascular infections, spotlighted by the severe acute respiratory syndrome coronavirus 2 pandemic, and its association with increased stroke risk is also reviewed. Rather than converging on a shared mechanism, these emerging studies implicate varied and distinct inflammatory processes in vascular brain injury and repair. Recognition of the phasic nature of inflammatory cascades on varying states of cerebrovascular disease is likely essential to the development and implementation of an anti-inflammatory strategy in the prevention, treatment, and repair of vascular brain injury. Although advances in revascularization have taught us that time is brain, targeting inflammation for the treatment of cerebrovascular disease will undoubtedly show us that timing is brain.

Search for Reliable Circulating Biomarkers to Predict Carotid Plaque Vulnerability

Atherosclerosis is responsible for 20% of ischemic strokes, and the plaques from the internal carotid artery the most frequently involved. Lipoproteins play a key role in carotid atherosclerosis since lipid accumulation contributes to plaque progression and chronic inflammation, both factors leading to plaque vulnerability. Carotid revascularization to prevent future vascular events is reasonable in some patients with high-grade carotid stenosis. However, the degree of stenosis alone is not sufficient to decide upon the best clinical management in some situations. In this context, it is essential to further characterize plaque vulnerability, according to specific characteristics (lipid-rich core, fibrous cap thinning, intraplaque hemorrhage). Although these features can be partly detected by imaging techniques, identifying carotid plaque vulnerability is still challenging. Therefore, the study of circulating biomarkers could provide adjunctive criteria to predict the risk of atherothrombotic stroke. In this regard, several molecules have been found altered, but reliable biomarkers have not been clearly established yet. The current review discusses the concept of vulnerable carotid plaque, and collects existing information about putative circulating biomarkers, being particularly focused on lipid-related and inflammatory molecules.

Interleukin-18 from neurons and microglia mediates depressive behaviors in mice with post-stroke depression

Post-stroke depression (PSD) is a common and serious complication that is affecting one thirds of stroke patients which leaves them with a poor quality of life, high mortality rate, high recurrent rate, and slow recovery. Recent studies showed that serum interleukin-18 (IL-18) level is a biomarker for patients with PSD. However, the role of IL-18 in the pathology of PSD is still unclear. In this study, we demonstrated that the IL-18 level in the ischemic brain significantly increased in mice with depression-like behaviors that were caused by the combined use of chronic spatial restraint stress and middle cerebral artery occlusion. Interestingly, IL-18 expression was mainly found in neurons at early phase and in microglia at a later phase. Injection of the exogenous IL-18 into the amygdala, but not the hippocampus or the striatum caused severe depression-like behaviors. On the contrary, the blockage of endogenous IL-18 by IL-18 binding protein, a specific antagonist of IL-18, repressed depressive phenotypes in SIR mice. IL-18 KO mice exhibited the resistance to spatial restraint stress and cerebral ischemia injury. Finally, we found that IL-18 mediated depressive behaviors by the interaction of IL-18 receptor and NKCC1, a sodium-potassium chloride co-transporter that is related to GABAergic inhibition. Administration of NKCC1 antagonist bumetanide exerted a therapeutic effect on the in IL-18-induced depressive mice. In conclusion, we demonstrated that increased IL-18 in the brain causes depression-like behaviors by promoting the IL-18 receptor/NKCC1 signaling pathway. Targeting IL-18 and its downstream pathway is a promising strategy for the prevention and treatment of PSD.

Growth differentiation factor-11 supplementation improves survival and promotes recovery after ischemic stroke in aged mice

Growth differentiation factor (GDF) 11 levels decline with aging. The age-related loss of GDF 11 has been implicated in the pathogenesis of a variety of age-related diseases. GDF11 supplementation reversed cardiac hypertrophy, bone loss, and pulmonary dysfunction in old mice, suggesting that GDF11 has a rejuvenating effect. Less is known about the potential of GDF11 to improve recovery after an acute injury, such as stroke, in aged mice. GDF11/8 levels were assessed in young and aged male mice and in postmortem human brain samples. Aged mice were subjected to a transient middle cerebral artery occlusion (MCAo). Five days after MCAo, mice received and bromodeoxyuridine / 5-Bromo-2'-deoxyuridine (BrdU) and either recombinant GDF11 or vehicle for five days and were assessed for recovery for one month following stroke. MRI was used to determine cerebrospinal fluid (CSF) volume, corpus callosum (CC) area, and brain atrophy at 30 days post-stroke. Immunohistochemistry was used to assess gliosis, neurogenesis, angiogenesis and synaptic density. Lower GDF11/8 levels were found with age in both mice and humans (p<0.05). GDF11 supplementation reduced mortality and improved sensorimotor deficits after stroke. Treatment also reduced brain atrophy and gliosis, increased angiogenesis, improved white matter integrity, and reduced inflammation after stroke. GDF11 may have a role in brain repair after ischemic injury.

An IL-18-centered inflammatory network as a biomarker for cerebral white matter injury

Chronic systemic sterile inflammation is implicated in the pathogenesis of cerebrovascular disease and white matter injury. Non-invasive blood markers for risk stratification and dissection of inflammatory molecular substrates in vivo are lacking. We sought to identify whether an interconnected network of inflammatory biomarkers centered on IL-18 and all previously associated with white matter lesions could detect overt and antecedent white matter changes in two populations at risk for cerebral small vessel disease. In a cohort of 167 older adults (mean age: 76, SD 7.1, 83 females) that completed a cognitive battery, physical examination, and blood draw in parallel with MR imaging including DTI, we measured cerebral white matter hyperintensities (WMH) and free water (FW). Concurrently, serum levels of a biologic network of inflammation molecules including MPO, GDF-15, RAGE, ST2, IL-18, and MCP-1 were measured. The ability of a log-transformed population mean-adjusted inflammatory composite score (ICS) to associate with MR variables was demonstrated in an age and total intracranial volume adjusted model. In this cohort, ICS was significantly associated with WMH (β = 0.222, p = 0.013), FW (β = 0.3, p = 0.01), and with the number of vascular risk factor diagnoses (r = 0.36, p<0.001). In a second cohort of 131 subjects presenting for the evaluation of acute neurologic deficits concerning for stroke, we used serum levels of 11 inflammatory biomarkers in an unbiased principal component analysis which identified a single factor significantly associated with WMH. This single factor was strongly correlated with the six component ICS identified in the first cohort and was associated with WMH in a generalized linear regression model adjusted for age and gender (p = 0.027) but not acute stroke. A network of inflammatory molecules driven by IL-18 is associated with overt and antecedent white matter injury resulting from cerebrovascular disease and may be a promising peripheral biomarker for vascular white matter injury.

Increased interleukin-18 level contributes to the development and severity of ischemic stroke

Although interleukin-18 (IL-18) has been implicated in the pathophysiology of stroke, research findings concerning IL-18 level in stroke have been inconsistent. Thus, we performed a cross-sectional study in patients with first-episode ischemic stroke and then extracted relevant data from databases to validate our results. A total of 252 patients and 259 healthy subjects were recruited, and serum IL-18 level was evaluated in a cross-sectional study. Then, we extracted data and conducted a meta-analysis, including 2,928 patients and 3,739 controls to support our results. A 95% confidence interval for standardized mean difference (SMD) was calculated using a Z test. We found IL-18 was higher in stroke patients than in controls (2.39 ± 0.25 vs. 2.25 ± 0.28, F=8.60, p=0.004) and was negatively associated with the NIHSS scale (r = -0.14, p=0.028). A subsequent meta-analysis confirmed that IL-18 level was higher in stroke patients than in controls (SMD = 2.14, 95% CI = 1.54 ∼ 2.73, P< 0.001). IL-18 level increased with the severity of the stroke (p< 0.01). These findings revealed increased IL-18 level contributed to the development and severity of ischemic stroke, suggesting the potential of this biomarker to become an important reference for the early monitoring of ischemic stroke.

Intracerebral hemorrhage induces monocyte-related gene expression within six hours: Global transcriptional profiling in swine ICH

Intracerebral hemorrhage (ICH) is a severe neurological disorder with no proven treatment. Our prior research identified a significant association with monocyte level and ICH mortality. To advance our understanding, we sought to identify gene expression after ICH using a swine model to test the hypothesis that ICH would induce peripheral blood mononuclear cell (PBMC) gene expression. In 10 pigs with ICH, two PBMC samples were drawn from each with the first immediately prior to ICH induction and the second six hours later. RNA-seq was performed with subsequent bioinformatics analysis using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Ingenuity® Pathway Analysis (IPA). There were 182 significantly upregulated and 153 significantly down-regulated differentially expressed genes (DEGs) after ICH. Consistent with findings in humans, significant GO and KEGG pathways were primarily related to inflammation and the immune response. Five genes, all upregulated post-ICH and known to be associated with monocyte activation, were repeatedly DEGs in the significant KEGG pathways: CD14, TLR4, CXCL8, IL-18, and CXCL2. In IPA, the majority of upregulated disease/function categories were related to inflammation and immune cell activation. TNF and LPS were the most significantly activated upstream regulators, and ERK was the most highly connected node in the top network. ICH induced changes in PBMC gene expression within 6 h of onset related to inflammation, the immune response, and, more specifically, monocyte activation. Further research is needed to determine if these changes affect outcomes and may represent new therapeutic targets.

Uric Acid Treatment After Stroke Prevents Long-Term Middle Cerebral Artery Remodelling and Attenuates Brain Damage in Spontaneously Hypertensive Rats

Hypertension is the most important modifiable risk factor for stroke and is associated with poorer post-stroke outcomes. The antioxidant uric acid is protective in experimental normotensive ischaemic stroke. However, it is unknown whether this treatment exerts long-term protection in hypertension. We aimed to evaluate the impact of transient intraluminal middle cerebral artery (MCA) occlusion (90 min)/reperfusion (1-15 days) on brain and vascular damage progression in adult male Wistar-Kyoto (WKY; n = 36) and spontaneously hypertensive (SHR; n = 37) rats treated (i.v./120 min post-occlusion) with uric acid (16 mg kg^-1) or vehicle (Locke's buffer). Ischaemic brain damage was assessed longitudinally with magnetic resonance imaging and properties of MCA from both hemispheres were studied 15 days after stroke. Brain lesions in WKY rats were associated with a transitory increase in circulating IL-18 and cerebrovascular oxidative stress that did not culminate in long-term MCA alterations. In SHR rats, more severe brain damage and poorer neurofunctional outcomes were coupled to higher cortical cerebral blood flow at the onset of reperfusion, a transient increase in oxidative stress and long-lasting stroke-induced MCA hypertrophic remodelling. Thus, stroke promotes larger brain and vascular damage in hypertensive rats that persists for long-time. Uric acid administered during early reperfusion attenuated short- and long-term brain injuries in both normotensive and hypertensive rats, an effect that was associated with abolishment of the acute oxidative stress response and prevention of stroke-induced long-lasting MCA remodelling in hypertension. These results suggest that uric acid might be an effective strategy to improve stroke outcomes in hypertensive subjects.

Alteration of microRNA 340-5p and Arginase-1 Expression in Peripheral Blood Cells during Acute Ischemic Stroke

Acute stroke alters the systemic immune response as can be observed in peripheral blood; however, the molecular mechanism by which microRNA (miRNA) regulates target gene expression in response to acute stroke is unknown. We performed a miRNA microarray on the peripheral blood of 10 patients with acute ischemic stroke and 11 control subjects. Selected miRNAs were quantified using a TaqMan assay. After searching for putative targets from the selected miRNAs using bioinformatic analysis, functional studies including binding capacity and protein expression of the targets of the selected miRNAs were performed. The results reveal a total of 30 miRNAs that were differentially expressed (16 miRNAs were upregulated and 14 miRNAs were downregulated) during the acute phase of stroke. Using prediction analysis, we found that miR-340-5p was predicted to bind to the 3'-untranslated region of the arginase-1 (ARG1) gene; a luciferase reporter assay confirmed the binding of miR-340-5p to ARG1. miR-340-5p was downregulated whereas ARG1 mRNA was upregulated in peripheral blood in patients experiencing acute stroke. Overexpression of miR-340-5p in human neutrophil and mouse macrophage cell lines induced downregulation of the ARG1 protein. Transfection with miR-340-5p increased nitric oxide production after LPS treatment in a mouse macrophage cell line. Our results suggest that several miRNAs are dynamically altered in the peripheral blood during the acute phase of ischemic stroke, including miR-340-5p. Acute stroke induces the downregulation of miR-340-5p, which subsequently upregulates ARG1 protein expression.

Association between genetic polymorphisms of interleukins and cerebral infarction risk: a meta-analysis

Interleukins (ILs) are the most typical inflammatory and immunoregulatory cytokines. Evidences have shown that polymorphisms in ILs are associated with cerebral infarction risk. However, the results remain inconclusive. The present study was to evaluate the role of ILs polymorphisms in cerebral infarction susceptibility. Relevant case-control studies published between January 2000 and December 2015 were searched and retrieved from the electronic databases of Web of Science, PubMed, Embase and the Chinese Biomedical Database. The odds ratio (OR) with its 95% confidence interval (CI) were employed to calculate the strength of association. A total of 55 articles including 12619 cerebral infarction patients and 14436 controls were screened out. Four ILs (IL-1, IL-6, IL-10 and IL-18) contained nine single nucleotide polymorphisms (SNPs; IL-1α -899C/T, IL-1β -511C/T and IL-1β +3953C/T; IL-6 -174G/C and -572C/G; IL-10 -819C/T and -1082A/G; IL-18 -607C/A and -137G/C). Our result showed that IL-1α -899C/T and IL-18 -607C/A (under all the genetic models), and IL-6 -572C/G (under the allelic model, heterogeneity model and dominant model) were associated with increased the risk of cerebral infarction (P<0.05). Subgroup analysis by ethnicity showed that IL-6 -174G/C polymorphism (under all the five models) and IL-10 -1082A/G polymorphism (under the allelic model and heterologous model) were significantly associated with increased the cerebral infarction risk in Asians. Other genetic polymorphisms were not related with cerebral infarction susceptibility under any genetic models. In conclusion, IL-1α -899C/T, IL-6 -572C/G and IL-18 -607C/A might be risk factors for cerebral infarction development. Further studies with well-designed and large sample size are still required.

The histone deacetylase inhibitor, sodium butyrate, exhibits neuroprotective effects for ischemic stroke in middle-aged female rats

Background

Sodium butyrate (NaB) is a histone deacetylase (HDAC) inhibitor exhibiting anti-inflammatory and neuroprotective effects in a rat ischemic model of stroke as well as a myocardial ischemia model. Although clinical evidence shows that older women are at higher risk for stroke occurrence and greater stroke severity, no studies have evaluated the effectiveness of NaB either in females or in older animals.

Methods

To determine the effects of NaB on stroke in older females, acyclic middle-aged Sprague-Dawley female rats (9–11 months old, constant diestrus) were subject to middle cerebral artery occlusion (MCAo) by intracerebral injection of recombinant endothelin-1. Rats were treated with NaB (300 mg/kg, i.p.) at 6 and 30 h following ET-1 injection. Animals were sacrificed at the early (2 days) or late (5 days) acute phase after MCAo. Serum and tissue lysates were collected for biochemical analyses.

Results

NaB treatment reduced infarct volume and ameliorated sensory motor impairment in middle-aged female rats, when measured at 2 and 5 days post MCAo. At the early acute phase (2 days post stroke), NaB treatment decreased brain lipid peroxides, and reduced serum levels of GFAP, a surrogate marker of blood-brain barrier (BBB) permeability. NaB also reduced expression of the inflammatory cytokine IL-1beta in circulation and IL-18 in the ischemic hemisphere. At the late acute phase (5 days post stroke), NaB treatment further suppressed MCAo-induced increase of IL-1beta, IL-17A, and IL-18 in brain lysates (cortex and striatum) from the ischemic hemisphere, and decreased ischemia-induced upregulation of IL-1beta and IL-18 in circulation, indicating a potent anti-inflammatory effect of the HDAC inhibitor. Moreover, NaB treatment also increased expression of IGF-1, a known neuroprotectant, in peripheral tissue including serum, liver, and spleen at the late acute phase.

Conclusions

These data provide the first evidence that delayed (>6 h) NaB treatment post-stroke is neuroprotective in older female rats. Additionally, these data also show that in addition to its well-known anti-inflammatory actions, NaB may exert a biphasic effect after stroke, operating initially to reduce BBB permeability and oxidative stress in the brain, and later, elevating IGF-1 expression in peripheral tissues.

Effects of interleukin-6, interleukin-18, and statin use, evaluated at acute stroke, on post-stroke depression during 1-year follow-up

Proinflammatory cytokines are associated with the development of post-stroke depression (PSD). Statins are thought to possess anti-inflammatory properties but their interactions with cytokines regarding the risk of PSD have yet to be investigated. Thus, the present study aimed to determine whether interleukin (IL)-6 and IL-18 were associated with the development of depression at 2 weeks and 1year after stroke using a longitudinal post-stroke cohort. Furthermore, this study examined the potential interactions between statin use and cytokines on PSD. For this study, 286 patients were evaluated 2 weeks after stroke and 222 patients were followed-up 1year later. Depression was diagnosed using criteria from the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) and then categorized into no PSD or any PSD, which included diagnoses of both major and minor depression. The effects of IL-6 and IL-18 on PSD as well as their interaction with a statin at both examination time-points were investigated using a multivariate logistic regression model. Higher IL-6 and IL-18 levels were independently associated with depressive disorders within 2 weeks and at 1year after stroke. When stratified by statin use, these significant associations were more evident in patients who did not use a statin. Furthermore, there was a significant interaction between statin use and IL-6 on the presence of a depressive disorder at 1year. The present findings support the cytokine hypothesis of PSD and indicate that the preventive effects of statin use against PSD may be mediated by its interactions with IL-6.

Interleukin-18 gene promoter 607A polymorphism, but not 137C polymorphism, is a protective factor for ischemic stroke in the Chinese population: A meta-analysis

Some epidemiological studies have evaluated the association between interleukin (IL)-18 promoter polymorphisms and the risk of ischemic stroke (IS), but the results were inconsistent. The present meta-analysis was therefore performed to investigate the relationship between IL-18 promoter 137G/C and 607C/A polymorphisms and the risk of IS in the Chinese population. Related studies from PubMed, Embase, Web of Science, CBMdisc and CNKI databases up to November 1, 2014 were systematically searched, also the reference lists of identified articles were manually searched. Information was extracted to calculate for the allelic, genotypic, dominant and recessive models using the pooled odds ratios (ORs) along with 95% confidence intervals (CIs). Evidence of significant association between 607C/A polymorphism and risk of IS was found in four genetic models based on the overall population. However, no significant association between 137G/C polymorphism and risk of IS was found in four genetic models. In summary, the present study suggests that IL-18 gene promoter 607A polymorphism is a protective factor for IS in the Chinese population, while 137C polymorphism has weaker or no protective properties. Still, a larger number of studies with large scale and sufficient original information are required to further confirm our findings.

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We performed a meta-analysis to investigate the relationship between IL-18 gene promoter polymorphisms and ischemic stroke.

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IL-18 gene promoter 607C/A polymorphism is a protective factor for ischemic stroke in the Chinese population.

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This is the first meta-analysis studying such association in Chinese ischemic stroke patients.

Serum pentraxin-3 levels in acute stroke: No association with stroke prognosis

BACKGROUND

Stroke is the leading cause of serious disability. Estimating severity of the disease and early risk assessment is crucial. Several studies have been carried on and several biomarkers have been proposed in the literature for risk assessment and to estimate the stroke prognosis. In this study we assessed the association of predictors such as patient age, gender, stroke volume and NIHS scores on prognosis of stroke event. We investigated whether the serum pentraxin-3 levels are linked with stroke prognosis.

METHODS

Forty-four stroke patients without cardiovascular risk factors were included in this study. Initial NIHS scores, stroke volumes, serum pentraxin-3 levels and the data regarding the risk factors were collected in the first and seventh days of event. Association of predictors with final NIHS scores were investigated using multivariate regression model.

RESULTS

Initial NIHS score, initial and final stroke volumes were independently associated with final NIHS score whereas serum pentraxin-3 levels, whether acquired at the first or seventh day of stroke, were not associated with final NIHS score.

CONCLUSIONS

In stroke patients without cardiovascular, cardiopulmonary and infectious diseases, serum pentraxin-3 levels are not associated with stroke prognosis.

Investigation on the IL-18 -607A/C and -137C/G on the susceptibility of ischemic stroke

OBJECTIVE

We conducted a case-control study with 322 cases and 322 controls to assess the role of the two common SNPs in the promoter of IL-18 gene.

METHODS

Polymerase chain reaction restriction fragment length of polymorphism (PCR-RFLP) was taken to genotype -607A/C and -137C/G in the promoter of the IL-18 gene.

RESULTS

By comparing cases and control subjects, we found that IS cases were more likely to have higher BMI, higher proportion of hypertension, and have higher proportion of smokers and drinkers. We found that IL-18 -607CC genotype (OR=1.70, 95% CI=1.03-2.81) and C allele (OR=1.26, 95% CI=1.01-1.58) were significantly more frequent in IS patients when compared with AA genotype. We did not find significant association between IL-18 -607A/C gene polymorphism and BMI, hypertension, smoking and drinking on the risk of IS.

CONCLUSION

Our study suggests that polymorphisms in IL-18 -607A/C can influence the development of IS, and this gene polymorphism is associated with risk of IS in a Chinese population.

Interleukin-18 deficiency and its long-term behavioural and cognitive impacts in a murine model of pneumococcal meningitis

Pneumococcal meningitis often results in death or neurological sequelae, but the underlying pathogenetic mechanisms remain poorly understood. In C57BL/6J mice subjected to intracerebroventricular (icv) challenge with Streptococcus pneumoniae, the chemokine CCL2 and cytokines interferon-γ, interleukin (IL)-1β, IL-6 and tumour necrosis factor were prominently expressed in the brain during the acute phase of the disease. The upregulation of these immune mediators was markedly diminished in IL-18-deficient mice. Uninfected IL-18(-/-) mice exhibited decreases in anxiety phenotype and licking behaviour, and an increase in behavioural habituation, in an automated monitoring system (the IntelliCage). Without antibiotic intervention, a majority of IL-18(+/+) mice developed irreversible disease after icv S. pneumoniae but this was significantly improved by deleting IL-18 gene function. IL-18(+/+) mice cured of pneumococcal meningitis with four doses of ceftriaxone, initiated at 20 h post-inoculation, showed enduring sequelae. These included abnormal behavioural phenotypes featuring diurnal hypoactivity and nocturnal hyperactivity, light phobia and disrupted cognitive function. While the hyperactive phenotype was absent in the corresponding IL-18(-/-) survivors, cognitive impairments and behavioural deficits were still present. Overall, the results suggest that the high levels of cytokines and/or chemokines released after pneumococcal challenge provoked a series of pathological events, ultimately causing acute death. Furthermore, since only a subset of behavioural phenotypes were ameliorated in the pneumococcus-infected IL-18(-/-) mice, the pathological pathways causing mortality may be, at least in part, distinct from those leading to long-term neurological sequelae.

Inflammasomes in the CNS

Microglia and macrophages in the CNS contain multimolecular complexes termed inflammasomes. Inflammasomes function as intracellular sensors for infectious agents as well as for host-derived danger signals that are associated with neurological diseases, including meningitis, stroke and Alzheimer's disease. Assembly of an inflammasome activates caspase 1 and, subsequently, the proteolysis and release of the cytokines interleukin-1β and interleukin-18, as well as pyroptotic cell death. Since the discovery of inflammasomes in 2002, there has been burgeoning recognition of their complexities and functions. Here, we review the current understanding of the functions of different inflammasomes in the CNS and their roles in neurological diseases.

Increased levels of serum IL-18 are associated with the long-term outcome of severe traumatic brain injury

OBJECTIVE

A long-lasting neuroinflammatory cascade may lead to the progression of brain damage, favoring neurodegeneration and cognitive impairment in patients with traumatic brain injury (TBI), but the potential mechanisms underlying this sequence of events remain elusive. Here we aimed to evaluate the impact of interleukin (IL)-18, a proinflammatory cytokine elevated in post-acute head injury and associated with neurodegeneration, on the long-term outcome of patients with chronic TBI.

METHODS

The serum content of IL-18 was evaluated in 16 patients with severe TBI, during their rehabilitation phase, and in a matched group of 16 healthy controls. The disability of the enrolled patients was evaluated by means of the Glasgow Outcome Scale, Levels of Cognitive Functioning, and the Disability Rating Scale.

RESULTS

The circulating levels of IL-18 were significantly increased in chronic TBI patients, as compared to healthy subjects, and correlated with the patients' cognitive impairment and disability severity.

CONCLUSIONS

IL-18 may contribute to the long-term outcome and neurodegeneration in TBI patients. Even though further studies are needed to understand the molecular mechanisms underlying the effects of IL-18 on TBI progression and its associated drop in cognitive function, a possible role of this cytokine as a therapeutic target in TBI can be envisaged.

High-sensitivity C-reactive protein, lipoprotein-related phospholipase A2, and acute ischemic stroke

BACKGROUND

Serum biomarkers may be useful for early diagnosis of acute ischemic stroke, exclusion of other diseases that may mimic stroke, and prediction of infarct volume. We evaluated serum high-sensitivity C-reactive protein (hs-CRP) and lipoprotein-related phospholipase A2 (Lp-PLA2) in patients who had acute ischemic stroke.

METHODS

In 200 patients who presented to an emergency service (acute ischemic stroke, 102 patients; control with no stroke, 98 patients), stroke patients were evaluated with the Canadian neurological scale and diffusion-weighted magnetic resonance imaging, and all patients were evaluated with the Glasgow coma scale and their serum hs-CRP level and Lp-PLA2 activity were assessed. The volume of stroke lesions was calculated from magnetic resonance images.

RESULTS

Patients who had stroke had higher mean serum hs-CRP level (stroke, 7±6 mg/dL; control, mean ± standard deviation 1±1 mg/dL; P≤0.001) and Lp-PLA2 activity (stroke, mean ± standard deviation 113±86 nmol/min/mL; control, mean ± standard deviation 103±50 nmol/min/mL; P≤0.001) than control patients who did not have stroke. The mean hs-CRP level and Lp-PLA2 activity were higher in patients who had greater stroke severity (lower Canadian neurological scale score) and were higher in patients who had larger volume strokes.

CONCLUSION

Higher hs-CRP level and Lp-PLA2 activity are significantly associated with more severe neurologic impairment and larger infarct size in patients who have acute ischemic stroke. These biomarkers may be useful for rapid diagnosis and prediction of ischemic tissue volume in the early stage of ischemic stroke. These findings may be important for health care facilities that have limited access to emergency computed tomography scanning for the diagnosis of stroke.

Serum interleukin-18 levels are associated with physical activity in Japanese men

Objective

To investigate the link between serum interleukin-18 (IL-18) levels and physical activity in Japanese men.

Methods

A total of 81 men (45.7±17.6 years old) was enrolled in this cross-sectional investigation study. We assessed anthropometric and body composition parameters. Serum IL-18 levels, physical activity by uniaxial accelerometers, peak oxygen uptake and metabolic risk parameters were also evaluated.

Results

Serum IL-18 levels were 179.4±84.7 pg/mL. Physical activity evaluated by Σ[metabolic equivalents × h per week (METs⋅h/w)]was significantly and negatively correlated with serum IL-18 levels (r = −0.252, p = 0.0235). These associations remained even after adjusting for age, peak oxygen uptake and other confounding factors.

Conclusion

Serum IL-18 levels were closely associated with physical activity independent of peak oxygen uptake in Japanese men.

Correlation between interleukin-18 promoter -607C/A polymorphism and susceptibility to ischemic stroke

Single nucleotide polymorphisms in the promoter region of interleukin-18 (IL-18), an inflammatory cytokine, have been linked to susceptibility to many diseases, including cancer and immune dysfunction. Here, we explored the potential association between the IL-18 -607C/A (rs1946518) promoter region polymorphism and susceptibility to ischemic stroke (IS). This locus was amplified from peripheral blood samples of 386 IS patients (cases) and 364 healthy individuals (controls) by the polymerase chain reaction with sequence-specific primers. Significant differences were observed by the χ² test in the -607C/A (rs1946518) genotype and allele frequencies between cases and controls (P < 0.05). Furthermore, after excluding for age, gender, smoking status, and hypertension, logistic regression indicated that IS susceptibility of -607C carriers increased 1.6 times (OR = 1.601, 95%CI = 1.148-2.233, P = 0.006) compared to -607A carriers. Additionally, similar increases in IS risk were noted for male patients or patients less than 65 years old. In conclusion, IL-18 -607C/A (rs1946518) promoter polymorphism is associated with IS susceptibility, and the C allele may confer increased IS risk.

Surgical stress induces an amplified inflammatory response in patients with type 2 diabetes

Background. Morbid obesity is believed to be an extreme of the metabolic spectrum. Moreover, diabetes is hypothesized to be associated with a chronic inflammatory state that is not observed in nondiabetic healthy individuals. We investigated the differences in expression of inflammatory cytokines induced by surgical stress between diabetic and nondiabetic individuals. Method. 39 morbidly obese patients undergoing laparoscopic Roux-en-Y gastric bypass (9 with type 2 diabetes mellitus) were compared with 8 nonobese euglycemic patients undergoing laparoscopic antireflux surgery. Cytokine levels for IL-6, IL-10, and IL-18 were measured 15 minutes before surgery and immediately after surgery. Results. IL-6 and IL-10 levels were elevated from baseline following surgery, but morbidly obese patients exhibited a much higher elevation than lean patients. Individuals with type 2 diabetes had the most pronounced IL-6 and IL-10 elevations. Baseline IL-18 levels were significantly higher in diabetic patients compared with nondiabetic or lean patients. However, IL-18 levels were not changed in response to surgery. Conclusions. Diabetes and morbid obesity are associated with augmented cytokine expression in response to surgical trauma that is several folds higher than in nonobese euglycemic patients. Diabetic patients exhibit a chronic elevation in IL-18 that is not changed by surgical stress.

Prospective study of IL-18 and risk of MI and stroke in men and women aged 60-79 years: a nested case-control study

Aim

IL-18 is hypothesized to destabilise atherosclerotic plaques, leading to thrombotic events and epidemiologic studies suggest that IL-18 may increase risk of CHD or CVD.

We examined prospective associations between levels of serum IL-18 and new CHD and stroke events in older men and women from a general population.

Methods

A case-control study was nested within a prospective cohort of men and women aged 60–79 years recruited from general practices in 25 British towns in 1998–2000 and followed-up for 7.5 years for fatal and non-fatal MI and stroke. Baseline IL-18 was measured in stored serum samples of incident cases of MI (n = 364) or stroke (n = 300) and two controls per case.

Results

Geometric mean IL-18 levels were higher among the 364 MI cases than the 706 controls; 417.84 pg/mL (IQR 316.25, 537.44) compared to 386.90 pg/mL (IQR 296.54, 482.33), p(difference) = 0.002. IL-18 was positively associated with adverse lipid and inflammatory profiles. Men and women in the top third of baseline IL-18 levels had an age and sex-adjusted odds ratio (OR) for MI of 1.31 (95%CI 0.92, 1.85) compared with those in the lowest third; this attenuated to 1.05 (95%CI 0.72, 1.53) after additional adjustment for established vascular and inflammatory risk factors. Each doubling of IL-18 level was associated with an increased OR for MI 1.34 (95%CI 1.04, 1.72), which was attenuated on adjustment for established vascular and inflammatory risk factors; 1.09 (95%CI 0.83, 1.44).

Geometric mean IL-18 levels did not differ between stroke cases and controls. The OR for stroke associated with the highest compared to the lowest tertile of IL-18 was 1.24 (95%CI 0.84, 1.84). Results for MI and stroke did not differ by presence of pre-existing CVD, gender or age.

Conclusions

Circulating IL-18 levels were strongly associated with a range of established and novel risk factors but were not independently associated with risk of MI or stroke in our study.

Alteration of immunologic responses on peripheral blood in the acute phase of ischemic stroke: blood genomic profiling study

OBJECTIVE

Peripheral blood cells and inflammatory mediators have a detrimental effect on brain during cerebral ischemia. We investigated the immunologic changes on peripheral blood in the acute phase of ischemic stroke using RNA microarray.

METHODS

mRNA microarray and real time-polymerase chain reaction (RT-PCR) for genes of interest in microarray data were analyzed in 12 stroke patients and 12 controls. Plasma matrix metalloproteinase-9 (MMP-9) concentrations were measured in 120 stroke patients and 82 controls.

RESULTS

In microarray analysis, a total of 11 genes of interest showed different expression in patients with ischemic stroke. The three most highly expressed genes were C19orf59 (chromosome 19 open reading frame 59), MMP9 and IL18RAP (interleukin-18 receptor accessory protein), whereas gene with the lowest expression was GNLY (granulysin). The expression patterns of three selected genes (MMP9, IL18RAP and GNLY) were validated by RT-PCR. The plasma concentration of MMP-9 was significantly elevated in the stroke patients, and showed a weakly positive correlation with infarct volume. Gene set enrichment analysis (GSEA) showed that gene sets related to immunity and defense, signal transduction, transport and cell adhesion were significant in acute ischemic stroke.

CONCLUSIONS

In the peripheral blood, numerous genes of inflammatory mediators, including MMP9, IL18RAP and GNLY, are altered in the acute phase of ischemic stroke. This stroke-specific gene expression profiling provides valuable information about the role of peripheral inflammation to the pathophysiological mechanism of ischemic stroke.

Serum levels of cytokines and C-reactive protein in acute ischemic stroke patients, and their relationship to stroke lateralization, type, and infarct volume

There is increasing evidence that inflammation plays an important role in the progression of acute ischemic stroke (AIS). The primary aims of this study were to examine the serum levels of 13 cytokines, C-reactive protein (CRP), glucose, and hemoglobin in AIS patients, and their relationship to stroke lateralization, type, and infarct volume. Forty-five patients with AIS were evaluated. Blood samples were taken within 72 h, and volumetric analyses performed within 1–7 days after AIS onset. Cytokines were measured in serum from all patients and from 40 control subjects using Luminex Bio-Plex XMap technology. The levels of interleukin (IL)-1ra (p < 0.001), IL-6 (p < 0.001), IL-8 (p < 0.001), IL-9 (p = 0.038), IL-10 (p = 0.001), IL-12 (p = 0.001), IL-18 (p < 0.001), and GRO-α (CXCL1) (p = 0.017) were significantly higher in the AIS patients than in the controls. The IL-8 level was significantly correlated with age in the patient group (r = 0.52, p < 0.001). None of the variables were found to be associated with stroke lateralization. Infarct volume was significantly positively correlated with CRP level (r = 0.47, p = 0.005). Patients with radiologically confirmed infarctions had significantly elevated serum levels of GRO-α (p = 0.023). The cytokine profile of the AIS patients supports not only earlier findings of a proinflammatory response but also early activation of endogenous immunosuppressive mechanisms. Novel findings of this study are elevated serum levels of IL-9 and GRO-α. Elevated GRO-α in AIS patients with radiologically confirmed infarctions suggests that GRO-α is specific for stroke of known etiology. Our results indicate that CRP plays an important role in the progression of cerebral tissue injury.

Interleukin-18 induces EMMPRIN expression in primary cardiomyocytes via JNK/Sp1 signaling and MMP-9 in part via EMMPRIN and through AP-1 and NF-kappaB activation

IL-18 and the extracellular matrix metalloproteinase (MMP) inducer (EMMPRIN) stimulate the expression of proinflammatory cytokines and MMPs and are elevated in myocardial hypertrophy, remodeling, and failure. Here, we report several novel findings in primary cardiomyocytes treated with IL-18. First, IL-18 activated multiple transcription factors, including NF-κB (p50 and p65), activator protein (AP)-1 (cFos, cJun, and JunD), GATA, CCAAT/enhancer-binding protein, myocyte-specific enhancer-binding factor, interferon regulatory factor-1, p53, and specific protein (Sp)-1. Second, IL-18 induced EMMPRIN expression via myeloid differentiation primary response gene 88/IL-1 receptor-associated kinase/TNF receptor-associated factor-6/JNK-dependent Sp1 activation. Third, IL-18 induced a number of MMP genes, particularly MMP-9, at a rapid rate as well as tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-3 at a slower rate. Finally, the IL-18 induction of MMP-9 was mediated in part via EMMPRIN and through JNK- and ERK-dependent AP-1 activation and p38 MAPK-dependent NF-κB activation. These results suggest that the elevated expression of IL-18 during myocardial injury and inflammation may favor EMMPRIN and MMP induction and extracellular matrix degradation. Therefore, targeting IL-18 or its signaling pathways may be of potential therapeutic benefit in adverse remodeling.

Thrombin antithrombin complex and IL-18 serum levels in stroke patients

The complex picture of inflammation and coagulation alterations comes to life in acute stroke phases. Increasing evidence points to a strong interaction and extensive crosstalk between the inflammation and coagulation systems: the interest towards this relationship has increased since recent experimental research showed that the early administration of antithrombin III (ATIII) decreases the volume of ischemia in mice and might be neuroprotective, playing an antiinflammatory role.

We aimed to establish the extent of the relationship among markers of inflammation (S100B and IL-18) and procoagulant and fibrinolytic markers (ATIII, thrombin-antithrombin III complex (TAT), Fibrin Degradation Products (FDP), D-dimer) in 13 comatose patients affected by focal cerebral ischemia.

Plasma levels of TAT, D-dimer and FDP, IL18 and S100B were increased. IL-18 and S100B high serum levels in ischemic patients suggest an early activation of the inflammatory cascade in acute ischemic injury.

The basic principles of the interaction between inflammatory and coagulation systems are revised, from the perspective that simultaneous modulation of both coagulation and inflammation, rather than specific therapies aimed at one of these systems could be more successful in stroke therapy.

Association of interleukin-18 levels with global arterial function and early structural changes in men without cardiovascular disease

BACKGROUND

Increased levels of interleukin-18 (IL-18) have been related to plaque progression and vulnerability and cardiovascular outcomes. Arterial functional and structural characteristics and endothelial/inflammatory activation are important determinants of cardiovascular performance and predictors of risk. We investigated whether IL-18 is a determinant of global arterial function and early structural changes in men.

METHODS

We evaluated arterial structural and functional characteristics (carotid-femoral pulse wave velocity (PWV), central aortic pressures, wave reflection indexes, flow-mediated dilation of the brachial artery, and common carotid intima-media thickness (IMT)) and we measured systemic inflammatory markers in 97 men (mean age 57.8 +/- 8.6 years) without manifest cardiovascular/atherosclerotic disease.

RESULTS

Multivariable analysis adjusting for age, mean pressure, other risk factors, high-sensitivity C-reactive protein (hsCRP), and treatment showed independent associations between IL-18 level and carotid-femoral PWV (P < 0.01) and IMT (P = 0.03). On the other hand, no relationship between IL-18 and flow-mediated dilation, central pressures or augmentation index (AIx) was found. The combination of higher IL-18 level with higher carotid-femoral PWV and carotid IMT values showed greater effect on 10-year risk of a cardiovascular event.

CONCLUSIONS

IL-18 level is independently associated with aortic stiffening and carotid early atherosclerosis. This finding underlines the important role of IL-18 as a marker of arterial damage, and implies a contribution of this compound to the pathophysiology of cardiovascular disease.

Interleukin 18 in the CNS

Interleukin (IL)-18 is a cytokine isolated as an important modulator of immune responses and subsequently shown to be pleiotropic. IL-18 and its receptors are expressed in the central nervous system (CNS) where they participate in neuroinflammatory/neurodegenerative processes but also influence homeostasis and behavior. Work on IL-18 null mice, the localization of the IL-18 receptor complex in neurons and the neuronal expression of decoy isoforms of the receptor subunits are beginning to reveal the complexity and the significance of the IL-18 system in the CNS. This review summarizes current knowledge on the central role of IL-18 in health and disease.

Interleukin-18 does not influence infarct volume or functional outcome in the early stage after transient focal brain ischemia in mice

Interleukin-18 (IL-18) is a proinflammatory cytokine of the interleukin-1 family which is upregulated after cerebral ischemia. The functional role of IL-18 in cerebral ischemia is unknown. In the present study, we compared infarct size in IL-18 knock-out and wild-type mice 24 hours and 48 hours after 1-hour transient middle cerebral artery occlusion (tMCAO). Moreover, the functional outcome was evaluated in a modified Bederson score, foot fault test and grip test. There were no significant differences in infarct size or functional outcome tests between wild-type and IL-18 knock-out mice. These data indicate that the early inflammatory response to cerebral ischemia does not involve IL-18, in contrast to other interleukin-1 family members such as interleukin-1.

Role of stromal cell-derived factor-1alpha, level and value of circulating interleukin-10 and endothelial progenitor cells in patients with acute myocardial infarction undergoing primary coronary angioplasty

BACKGROUND

The relationships among the circulating levels of endothelial progenitor cells (EPC), stromal cell-derived factor (SDF)-1alpha, interleukin (IL)-10 and outcome were examined in patients with ST-segment elevation acute myocardial infarction (ST-se AMI) undergoing primary coronary angioplasty.

METHODS AND RESULTS

Circulating levels of IL-10, SDF-1alpha, and EPCs [defined by staining markers: CD31/CD34 (E(1)) and KDR/CD34 (E(2))] were examined by ELISA and flow cytometry, respectively. The IL-10 level was higher, whereas the circulating level of EPCs (E(1-2)) was lower (all P<0.05) in AMI patients than in normal subjects. Additionally, the SDF-1alpha level was significantly and independently predictive of an increased level of circulating EPCs (E(1-2)) (P<0.0001). Furthermore, patients with a high SDF-1alpha level (>1,500 pg/ml) had lower left ventricular performance, higher Killip score (defined as >or=3), and increased 30-day mortality than those with low SDF-1alpha level (<or=1,500 pg/ml) (all P<0.007). Moreover, high circulating levels of E(2) and IL-10 were the most significant independent predictors of increased 30-day major adverse clinical outcome (MACO) (defined as advanced Killip score >or=3 or 30-day mortality) (P<0.01).

CONCLUSIONS

The serum SDF-1alpha level is independently predictive of an increased level of circulating EPCs (E(1-2)). E(2) and IL-10 are major independent predictors of 30-day MACO in ST-se AMI patients undergoing primary coronary angioplasty.

Post-ischemic brain damage: pathophysiology and role of inflammatory mediators

Neuroinflammatory mediators play a crucial role in the pathophysiology of brain ischemia, exerting either deleterious effects on the progression of tissue damage or beneficial roles during recovery and repair. Within hours after the ischemic insult, increased levels of cytokines and chemokines enhance the expression of adhesion molecules on cerebral endothelial cells, facilitating the adhesion and transendothelial migration of circulating neutrophils and monocytes. These cells may accumulate in the capillaries, further impairing cerebral blood flow, or extravasate into the brain parenchyma. Infiltrating leukocytes, as well as resident brain cells, including neurons and glia, may release pro-inflammatory mediators, such as cytokines, chemokines and oxygen/nitrogen free radicals that contribute to the evolution of tissue damage. Moreover, recent studies have highlighted the involvement of matrix metalloproteinases in the propagation and regulation of neuroinflammatory responses to ischemic brain injury. These enzymes cleave protein components of the extracellular matrix such as collagen, proteoglycan and laminin, but also process a number of cell-surface and soluble proteins, including receptors and cytokines such as interleukin-1beta. The present work reviewed the role of neuroinflammatory mediators in the pathophysiology of ischemic brain damage and their potential exploitation as drug targets for the treatment of cerebral ischemia.

Immune and inflammatory responses to stroke: good or bad?

Inflammatory and immune responses play important roles following ischaemic stroke. Inflammatory responses contribute to damage and also contribute to repair. Injury to tissue triggers an immune response. This is initiated through activation of the innate immune system. In stroke there is microglial activation. This is followed by an influx of lymphocytes and macrophages into the brain, triggered by production of pro-inflammatory cytokines. This inflammatory response contributes to further tissue injury. There is also a systemic immune response to stroke, and there is a degree of immunosuppression that may contribute to the stroke patient's risk of infection. This immunosuppressive response may also be protective, with regulatory lymphocytes producing cytokines and growth factors that are neuroprotective. The specific targets of the immune response after stroke are not known, and the details of the immune and inflammatory responses are only partly understood. The role of inflammation and immune responses after stroke is twofold. The immune system may contribute to damage after stroke, but may also contribute to repair processes. The possibility that some of the immune response after stroke may be neuroprotective is exciting and suggests that deliberate enhancement of these responses may be a therapeutic option.

Adipocytokines and risk of stroke in older people: a nested case-control study

BACKGROUND

Inflammation may play an important role in atherothrombosis and in promoting cerebral damage after stroke. We hypothesized that plasma adipocytokine concentrations would be associated with risk of stroke in older people.

METHODS

Nested case-control study from the Prospective Study of Pravastatin in the Elderly (PROSPER). Subjects were aged 70-82 years and followed up for a mean of 3.2 years: 266 incident stroke cases (179 confirmed as ischaemic) were compared with 532 controls matched for age, gender and treatment allocation (pravastatin or placebo). Adipocytokines [adiponectin, interleukin- (IL-)18 and tumour necrosis factor (TNF)alpha] were measured on stored baseline plasma samples.

RESULTS

Elevated plasma adiponectin was associated with lower risk of ischaemic stroke on univariate analysis: odds ratio (OR) 0.78 per 1 SD increase (95% CI 0.62-0.97). There were no associations of IL-18 or TNFalpha with risk for ischaemic or total strokes. In multivariate models the independent predictors of ischaemic stroke were prior cerebrovascular accident (OR 2.68, 95% CI 1.60-4.50), any alcohol use (1.98, 1.33-2.94), triglycerides (1.40, 1.11-1.77), Barthel score (0.75, 0.58-0.96) and known diabetes (1.72, 1.04-2.83); adiponectin, IL-18 and TNFalpha did not contribute. A similar pattern of risk was seen for total stroke.

CONCLUSIONS

Reduced adiponectin may have a modest role in the aetiology of ischaemic stroke in older people, however IL-18 and TNFalpha are unlikely to play any important part. These adipocytokines do not have clinical predictive utility; history of prior cerebrovascular accident, known diabetes mellitus, prior disability and higher alcohol intake explain much of the stroke risk.

Inducible heat shock protein 70, interleukin-18, and tumor necrosis factor alpha correlate with outcomes in spontaneous intracerebral hemorrhage

Inducible heat shock protein 70 (HSP70), a stress protein detected in the central nervous system, is expressed when a cell or organism is under stress. Interleukin-18 (IL-18) and tumor necrosis factor alpha (TNF-alpha) are multipotential early proinflammatory cytokines. Our objective was to determine protein levels of HSP70, IL-18, and TNF-alpha as well as mRNA levels of HSP70, IL-18, and TNF-alpha in the plasma and CSF of spontaneous intracerebral hemorrhage (ICH) patients, and to correlate these with disease outcome. Serial measurement of the proteins in CSF and plasma and of the mRNAs in peripheral blood mononuclear cells was conducted in 43 patients (mean age, 64+/-9 years; 23 men and 20 women). Ten (23%) patients died. We found that the damaged brain releases TNF-alpha and HSP70 to the peripheral blood and that plasma levels of these are highly associated with mortality in spontaneous ICH patients.

Predictive value of IL-18 and SC5b-9 for neurocognitive dysfunction after cardiopulmonary bypass

BACKGROUND

Neurological injury after cardiopulmonary bypass (CPB) continues to be a major problem after cardiac surgery. The aim of this study was to investigate the predictive value of Interleukin-18 (IL-18) and SC5b-9 as biochemical markers of neurocognitive dysfunction after cardiac surgery.

METHODS

A total of 30 patients undergoing elective cardiac surgery using CPB were recruited. Blood samples were obtained for IL-18 and SC5b-9 concentrations before induction, 24, 48, 72, 96 and 120 h post-CPB and 6 weeks after operation. In addition, patients underwent a standard battery of neuropsychometric tests before operation and at day 5 and 6 weeks after operation.

RESULTS

Serum concentration of IL-18, but not SC5b-9, was significantly different between patients with and without neurocognitive dysfunction; serum IL-18 concentration significantly increased in patients with neurocognitive dysfunction (P = 0.018). Neurological outcome was significantly dependent on peak difference in IL-18 concentration at day 5 (P = 0.033), but not on peak difference in SC5b-9 concentration (P = 0.16). Eight patients had neurocognitive dysfunction at day 5 and three had neurocognitive dysfunction at 6 weeks. In a very small number of patients, no significant association was demonstrated between IL-18 or SC5b-9 concentrations and neurocognitive dysfunction at 6 weeks.

CONCLUSIONS

IL-18 has the potential as a useful marker of neurological dysfunction, requiring further investigation.

Inflammation in adult and neonatal stroke

This chapter will discuss the current knowledge of the contribution of systemic and local inflammation in acute and sub-chronic stages of experimental stroke in both the adult and neonate. It will review the role of specific cell types and interactions among blood cells, endothelium, glia, microglia, the extracellular matrix and neurons - cumulatively called "neurovascular unit" - in stroke induction and evolution. Intracellular inflammatory signaling pathways such as nuclear factor kappa beta and mitogen-activated protein kinases, and mediators produced by inflammatory cells such as cytokines, chemokines, reactive oxygen species and arachidonic acid metabolites, as well as the modifying role of age on these mechanisms, will be reviewed as well as the potential for therapy in stroke and hypoxic-ischemic injury.

The etiology of poststroke depression: a review of the literature and a new hypothesis involving inflammatory cytokines

Although poststroke depression is unlikely to represent a single disorder and numerous etiologies for different kinds of poststroke depression will likely emerge as the result of future research, we believe that a number of poststroke depressive disorders are likely to be the result of specific changes in brain pathology and neurophysiology. Nevertheless, there are relatively few hypotheses about the pathophysiology of poststroke depression. This paper, therefore, proposes a new hypothesis for poststroke depression involving increased production of proinflammatory cytokines resulting from brain ischemia in cerebral areas linked to the pathogenesis of mood disorders. This paper reviews the evidence supporting the hypothesis that proinflammatory cytokines are involved in the occurrence of stroke as well as mood disorders linked to the brain damage. The increased production of proinflammatory cytokines such as IL-1beta, TNF-alpha or IL-18 resulting from stroke may lead to an amplification of the inflammatory process, particularly in limbic areas, and widespread activation of indoleamine 2,3-dioxygenase (IDO) and subsequently to depletion of serotonin in paralimbic regions such as the ventral lateral frontal cortex, polar temporal cortex and basal ganglia. The resultant physiological dysfunction may lead to poststroke depression. Future investigations may explore this hypothesis through more extensive studies on the role of proinflammatory cytokines, such as IL-1beta, TNF-alpha or even IL-18, in patients with poststroke depression.

Chitotriosidase and inflammatory mediator levels in Alzheimer's disease and cerebrovascular dementia

Inflammation has been reported to be involved in the pathogenesis of cerebrovascular dementias (CvDs). This study investigated the involvement of Chitotriosidase (ChT), a chinolitic enzyme mainly produced by activated macrophages, in the pathophysiology of Alzheimer's disease (AD) and ischemic CvD. In addition, the levels of interleukin (IL)-16, IL-18, transforming growth factor (TGF)-beta1 and superoxide anion (O2(-)) were determined to evaluate the relationship between ChT levels, these cytokines and oxidative stress in both AD and ischemic CvD patients. The levels of ChT and IL-16, IL-18, and TGF-beta1 mRNA were investigated using quantitative real-time polymerase chain reaction on macrophages of peripheral blood of 40 patients with AD, 40 patients with ischemic CvD and 40 non-demented age-matched subjects. The results show that ChT, IL-16 and O2(-) levels significantly increased in ischemic CvD patients compared with AD patients and were significantly and positively correlated with IL-18 and O2(-). The production of IL-18 was increased in both AD and ischemic CvD patients. TGF-beta1 expression was higher in AD patients and was inversely correlated with the expression of ChT, IL-16 and IL-18, respectively. In non-demented age-matched subjects no significant changes in ChT and IL-16, IL-18, and TGF-beta1 expression were found. Our results indicate that ChT, IL-16, IL-18 and TGF-beta1 are increased in ischemic CvD and AD, confirming that the immune system may play an important role in the development and progression of neurodegenerative disorders. In addition, the present findings suggest that ChT could also play a crucial role in pathological conditions such as CvD in which the inflammatory process is activated.