Rachel F. Georgiou

Peak plasma interleukin-6 and other peripheral markers of inflammation in the first week of ischaemic stroke correlate with brain infarct volume, stroke severity and long-term outcome

BackgroundCerebral ischaemia initiates an inflammatory response in the brain and periphery. We assessed the relationship between peak values of plasma interleukin-6 (IL-6) in the first week after ischaemic stroke, with measures of stroke severity and outcome.MethodsThirty-seven patients with ischaemic stroke were prospectively recruited. Plasma IL-6, and other markers of peripheral inflammation, were measured at pre-determined timepoints in the first week after stroke onset. Primary analyses were the association between peak plasma IL-6 concentration with both modified Rankin score (mRS) at 3 months and computed tomography (CT) brain infarct volume.ResultsPeak plasma IL-6 concentration correlated significantly (p < 0.001) with CT brain infarct volume (r = 0.75) and mRS at 3 months (r = 0.72). It correlated similarly with clinical outcome at 12 months or stroke severity. Strong associations were also noted between either peak plasma C-reactive protein (CRP) concentration or white blood cell (WBC) count, and all outcome measures.ConclusionsThese data provide evidence that the magnitude of the peripheral inflammatory response is related to the severity of acute ischaemic stroke, and clinical outcome.

A randomised phase II study of interleukin-1 receptor antagonist in acute stroke patients

Objectives: The cytokine interleukin (IL)-1 mediates ischaemic brain damage in rodents. The endogenous, highly selective, IL-1 receptor antagonist (IL-1ra) protects against ischaemic cerebral injury in a range of experimental settings, and IL-1ra causes a marked reduction of cell death when administered peripherally or at a delay in transient cerebral ischaemia. We report here the first randomised, double blind, placebo controlled trial of recombinant human IL-1ra (rhIL-1ra) in patients with acute stroke. Methods: Patients within 6 hours of the onset of symptoms of acute stroke were randomised to rhIL-1ra or matching placebo. Test treatment was administered intravenously by a 100 mg loading dose over 60 seconds, followed by a 2 mg/kg/h infusion over 72 h. Adverse events and serious adverse events were recorded for up to 3 months, serial blood samples were collected for biological markers up to 3 months, and 5–7 day brain infarct volume was measured by computed tomography. Results: No adverse events were attributed to study treatment among 34 patients randomised. Markers of biological activity, including neutrophil and total white cell counts, C reactive protein, and IL-6 concentrations, were lower in rhIL-1ra treated patients. Among patients with cortical infarcts, clinical outcomes at 3 months in the rhIL-1ra treated group were better than in placebo treated. Conclusions: These data suggest that rhIL-1ra is safe and well tolerated in acute stroke. In addition, rhIL-1ra exhibited biological activity that is relevant to the pathophysiology and clinical outcome of ischaemic stroke. Our findings identify rhIL-1ra as a potential new therapeutic agent for acute stroke.

An early and sustained peripheral inflammatory response in acute ischaemic stroke: relationships with infection and atherosclerosis

Central nervous system and peripheral inflammation is important in the responses to ischaemic stroke, and may also predispose to its development. We aimed to identify (1) the extent to which a peripheral inflammatory response is activated in patients following acute stroke, and (2) whether there was evidence for preexisting peripheral inflammation. Thirty-six patients with ischaemic stroke within 12 h of onset of symptoms had serial blood samples taken up to 12 months for analysis of markers of inflammation. Thirty-six control subjects, individually matched for age, sex and degree of atherosclerosis, were also studied. Median C-reactive protein (CRP) was elevated, relative to controls (2.08 mg/l), from admission (4.31 mg/l) (p</=0.001) until 3 months (2.90 mg/l) (p</=0.01), the greatest elevation occurring at 5-7 days (17.67 mg/l) (p</=0.001). Elevations were also seen in erythrocyte sedimentation rate (ESR) and white blood cell (WBC) count until 3 months. Median plasma IL-6 was also elevated, relative to controls (9 pg/ml), by 24 h after onset of symptoms (22 pg/ml) (p</=0.01), and remained elevated at 5-7 days (23 pg/ml) (p</=0.01), but not at 3 months. Less marked elevations in these markers were seen in patients without evidence of infection except for IL-6, which was not increased in the absence of infection. These data provide evidence of an early and sustained peripheral inflammatory response to acute ischaemic stroke in patients with or without evidence of infection. The very early increase in concentrations of inflammatory markers after stroke may either be induced by stroke itself, or may indicate a preexisting inflammatory condition in stroke patients which may contribute to the development of stroke.

Brain inflammation is induced by co-morbidities and risk factors for stroke

Highlights ► Risk factors for stroke include atherosclerosis, obesity, diabetes and hypertension. ► Stroke risk factors are associated with peripheral inflammation. ► Corpulent rats and atherogenic mice show increased inflammation in the brain. ► Pilot data show that patients at risk of stroke may also develop brain inflammation. ► Chronic peripheral inflammation can drive inflammatory changes in the brain.

Interleukin-1 receptor antagonist penetrates human brain at experimentally therapeutic concentrations.

The proinflammatory cytokine interleukin (IL)-1 mediates several forms of experimentally induced acute brain injury and has been implicated in chronic neurodegenerative disorders. The IL-1 receptor antagonist, IL-1RA, protects rodents against ischaemic brain injury, but its molecular mass (17 kDa) potentially limits the brain penetration of peripherally administered IL-1RA. We therefore sought to identify whether therapeutically effective concentrations of IL-1RA in the rat were also achieved in brain of patients with subarachnoid haemorrhage (SAH), using a peripheral administration regime that had proved to be safe and reduce peripheral inflammation in patients after stroke. An intravenous bolus of IL-1RA, followed by infusion, was administered to rats after induction of focal cerebral ischaemia. The effects of IL-1RA on brain ischaemia and the concentrations achieved in cerebrospinal fluid (CSF), were determined. Interleukin-1 receptor antagonist was similarly administered to patients with SAH, and CSF was sampled via external ventricular drains. In rats, IL-1RA significantly reduced brain injury induced by focal cerebral ischaemia. The plasma IL-1RA concentrations reached 12±2 μg/mL by 30 mins, and CSF concentrations were maintained between 91 and 232 ng/mL between 1 and 24 h of infusion. In patients with SAH, IL-1RA reached a steady-state plasma concentration of 22 ± 4 μg/mL by 15 mins, and CSF concentrations were maintained at 78 to 558 ng/mL between 1 and 24 h. Intravenous delivery of IL-1RA leads to CSF concentrations in patients comparable to those that are neuroprotective in rats, and might therefore be of therapeutic benefit.

Clinical outcome following acute ischaemic stroke relates to both activation and autoregulatory inhibition of cytokine production

BackgroundAs critical mediators of local and systemic inflammatory responses, cytokines are produced in the brain following ischaemic stroke. Some have been detected in the circulation of stroke patients, but their role and source is unclear. Focusing primarily on interleukin(IL)-1-related mechanisms, we serially measured plasma inflammatory markers, and the production of cytokines by whole blood, from 36 patients recruited within 12 h and followed up to 1 year after acute ischaemic stroke (AIS).ResultsAdmission plasma IL-1 receptor antagonist (IL-1ra) concentration was elevated, relative to age-, sex-, and atherosclerosis-matched controls. IL-1β, soluble IL-1 receptor type II, tumour necrosis factor (TNF)-α, TNF-RII, IL-10 and leptin concentrations did not significantly differ from controls, but peak soluble TNF receptor type I (sTNF-RI) in the first week correlated strongly with computed tomography infarct volume at 5–7 days, mRS and BI at 3 and 12 months. Neopterin was raised in patients at 5–7 d, relative to controls, and in subjects with significant atherosclerosis. Spontaneous IL-1β, TNF-α and IL-6 gene and protein expression by blood cells was minimal, and induction of these cytokines by lipopolysaccharide (LPS) was significantly lower in patients than in controls during the first week. Minimum LPS-induced cytokine production correlated strongly with mRS and BI, and also with plasma cortisol.ConclusionAbsence of spontaneous whole blood gene activation or cytokine production suggests that peripheral blood cells are not the source of cytokines measured in plasma after AIS. Increased plasma IL-1ra within 12 h of AIS onset, the relationship between sTNF-RI and stroke severity, and suppressed cytokine induction suggests early activation of endogenous immunosuppressive mechanisms after AIS.

Variability of the systemic acute phase response after ischemic stroke

Despite apparent relationships between ischemic stroke and the acute phase response (APR), considerable variation in the APR exists between individuals. We therefore performed post-hoc analysis of individual APR profiles in 31 patients with ischemic stroke in relation to volume of brain infarction. Patients with ischemic stroke had serial blood samples taken within 12 h, and up to 12 months of symptom onset, for analysis of plasma C-reactive protein (CRP) and interleukin-6 (IL-6). Computed tomography (CT) brain infarct volume was measured at 5 to 7 days (median 23.9 cm(3)). An increase in plasma CRP after the admission sample was evident in 94% of patients by day 5 to 7 (median increase 558% of admission value). CRP response, assessed as area under the curve between admission and day 5 to 7, correlated strongly (r=0.62, p<0.001) with CT infarct volume. Those with greater infarct volumes had more evidence of infection, either prior to or during the first week after stroke. The pattern of response was similar for IL-6, although only 77% showed an increase in plasma IL-6 after the admission sample (median increase 148% of admission value). These data suggest that, although infection and other factors may contribute to systemic inflammation, the extent of acute brain injury after ischemic stroke is a major factor influencing the magnitude and variability of the APR.

Prognosis in patients with transient ischaemic attack (TIA) and minor stroke attending TIA services in the North West of England: The NORTHSTAR Study

Background: The ABCD2 score predicts stroke risk within a few days of transient ischaemic attack (TIA). It is not clear whether the predictive value of the ABCD2 score can be generalised to UK TIA services, where delayed presentation of TIA and minor stroke are common. We investigated prognosis, and the use of the ABCD2 score, in patients attending TIA services in the North West of England with a diagnosis of TIA or minor stroke. Methods: 711 patients with TIA or minor stroke were prospectively recruited from five centres (median duration from index event to recruitment 15 days). The primary outcome was the composite of incident TIA, stroke, acute coronary syndrome or cardiovascular death at the 3 month follow-up. Prognostic factors were analysed using Cox proportional hazards regression. Results: The primary outcome occurred in 126 (18%) patients. Overall, there were 30 incident strokes. At least one incident TIA occurred in 100 patients (14%), but only four had a subsequent stroke. In multifactorial analyses, the ABCD2 score was unrelated to the risk of the primary outcome, but predicted the risk of incident stroke: score 4–5: hazard ratio (HR) 3.4 (95% CI 1.0 to 12); score 6–7: HR 4.8 (1.3 to 18). Of the components of the ABCD2 score, unilateral motor weakness predicted both the primary outcome (HR 1.8 (1.2 to 2.8)) and stroke risk (HR 4.2 (1.3 to 14)). Conclusions: In patients attending typical NHS TIA services, the risk of incident stroke was relatively low, probably reflecting delays to assessment. Current provision of TIA services, where delayed presentation to “rapid access” TIA clinics is common, does not appear to provide an appropriate setting for urgent evaluation, risk stratification or timely secondary prevention for those who may be at highest risk.

Potential surrogate markers of cerebral microvascular angiopathy in asymptomatic subjects at risk of stroke

Cerebral microvascular angiopathy (MVA) is associated with clinical vascular risk factors and is characterised by histological changes, including thickening of the walls of arterial vessels and dilatation of the Virchow-Robin spaces (VRS). We have previously described two novel biomarkers of MVA based on magnetic resonance imaging (MRI), VRS dilatation and abnormalities in the transfer of systolic arterial pulsation to the ventricular CSF, which occur as a result of decreased cerebral arterial compliance. These are associated with vascular dementia and treatment-resistant late onset depression. We studied a group of normal subjects at risk of cerebrovascular disease to determine if these biomarkers are present in patients who have no evidence of symptomatic vascular disease. We studied 31 subjects, 16 with three or more vascular risk factors and 15 with one or less significant risk factors. We measured arterial blood flow and CSF flow in the cerebral aqueduct, white matter lesion load, and the distribution and number of VRS. There were significant differences in CSF pulsatility and in VRS in the basal ganglia between the two groups, but no differences in white matter lesion load. We conclude that asymptomatic subjects at risk of stroke have MRI evidence of MVA before white matter lesions become apparent.

Does inflammation predispose to recurrent vascular events after recent transient ischaemic attack and minor stroke? The North West of England transient ischaemic attack and minor stroke (NORTHSTAR) study

Background and hypothesis Inflammation is implicated in the pathogenesis and outcome of ischaemic injury. Poststroke inflammation is associated with outcome but it remains unclear whether such inflammation precedes or results from ischaemic injury. We hypothesised that inflammatory markers are associated with an increased risk of recurrent vascular events soon after transient ischaemic attack and minor stroke. Methods This was a multicentre, prospective, nested case–control study. Plasma concentrations of C-reactive protein, interleukin-6, interleukin-1-receptor antagonist and fibrinogen, leucocyte counts, erythrocyte sedimentation rate and inflammatory gene allele frequencies were analysed in 711 patients with recent transient ischaemic attack or minor stroke. Cases were defined by the incidence of one or more recurrent vascular events during the three-month follow-up. Association of inflammatory markers with case-status was determined using conditional logistic regression. Results Plasma concentrations of C-reactive protein, interleukin-1-receptor antagonist and interleukin-6 were not associated with case-status. In secondary analyses, only erythrocyte sedimentation rate was significantly associated with case-status (odds ratio 1·39, 95% confidence interval 1·03–1·85; P=0·03), but this effect did not persist after adjustment for smoking and past history of transient ischaemic attack or stroke. Single nucleotide polymorphisms in four inflammatory genes (interleukin-6, fibrinogen, P-selectin and vascular cell adhesion molecule-1) were nominally associated with case-status. Conclusions Circulating inflammatory markers were not associated with recurrent vascular events. Nominally significant associations between genetic markers and case-status will require replication. These data provide little evidence for an inflammatory state predisposing to stroke and other vascular events in a susceptible population.