Craig J. Smith

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.

Evaluation of C-Reactive Protein Measurement for Assessing the Risk and Prognosis in Ischemic Stroke: A Statement for Health Care Professionals From the CRP Pooling Project Members

Background and Purpose— Several studies have shown, in different populations, that modest elevation of plasma C-reactive protein (CRP) in the range seen in apparently healthy individuals is a strong predictor of future vascular events. Elevated plasma CRP concentrations are also associated with an increased risk of cerebrovascular events and an increased risk of fatal and nonfatal cardiovascular events in ischemic stroke patients. These epidemiological and clinical observations suggest that determination of plasma CRP concentrations could be used as an adjunct for risk assessment in primary and secondary prevention of cerebrovascular disease and be of prognostic value. The aim of this review is to summarize the evidence for CRP as an independent predictor of cerebrovascular events in at-risk individuals and ischemic stroke patients and to consider its usefulness in evaluating prognosis after stroke. Summary of Review— CRP fulfils most of the requirements of a new risk and prognostic predictor, but several issues await further confirmation and clarification before this marker can be included in the routine evaluation of stroke patients and subjects at risk for cerebrovascular disease. Potentially important associations have been established between elevated plasma CRP concentrations and increased efficacy of established therapies, particularly lipid-lowering therapy with statins. Conclusion— At present, there is not sufficient evidence to recommend measurement of CRP in the routine evaluation of cerebrovascular disease risk in primary prevention, because there is insufficient evidence as to whether early detection, or intervention based on detection, improves health outcomes, although shared risk of cardiovascular disease indicates this may be of value. In secondary prevention of stroke, elevated CRP adds to existing prognostic markers, but it remains to be established whether specific therapeutic options can be derived from this.

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.

Detection of Atrial Fibrillation After Ischemic Stroke or Transient Ischemic Attack A Systematic Review and Meta-Analysis

Background and Purpose— Atrial fibrillation (AF) confers a high risk of recurrent stroke, although detection methods and definitions of paroxysmal AF during screening vary. We therefore undertook a systematic review and meta-analysis to determine the frequency of newly detected AF using noninvasive or invasive cardiac monitoring after ischemic stroke or transient ischemic attack. Methods— Prospective observational studies or randomized controlled trials of patients with ischemic stroke, transient ischemic attack, or both, who underwent any cardiac monitoring for a minimum of 12 hours, were included after electronic searches of multiple databases. The primary outcome was detection of any new AF during the monitoring period. We prespecified subgroup analysis of selected (prescreened or cryptogenic) versus unselected patients and according to duration of monitoring. Results— A total of 32 studies were analyzed. The overall detection rate of any AF was 11.5% (95% confidence interval, 8.9%–14.3%), although the timing, duration, method of monitoring, and reporting of diagnostic criteria used for paroxysmal AF varied. Detection rates were higher in selected (13.4%; 95% confidence interval, 9.0%–18.4%) than in unselected patients (6.2%; 95% confidence interval, 4.4%–8.3%). There was substantial heterogeneity even within specified subgroups. Conclusions— Detection of AF was highly variable, and the review was limited by small sample sizes and marked heterogeneity. Further studies are required to inform patient selection, optimal timing, methods, and duration of monitoring for detection of AF/paroxysmal AF.

Detection of atrial fibrillation after ischemic stroke or TIA: a systematic review and meta-analysis.

Background and Purpose— Atrial fibrillation (AF) confers a high risk of recurrent stroke, although detection methods and definitions of paroxysmal AF during screening vary. We therefore undertook a systematic review and meta-analysis to determine the frequency of newly detected AF using noninvasive or invasive cardiac monitoring after ischemic stroke or transient ischemic attack. Methods— Prospective observational studies or randomized controlled trials of patients with ischemic stroke, transient ischemic attack, or both, who underwent any cardiac monitoring for a minimum of 12 hours, were included after electronic searches of multiple databases. The primary outcome was detection of any new AF during the monitoring period. We prespecified subgroup analysis of selected (prescreened or cryptogenic) versus unselected patients and according to duration of monitoring. Results— A total of 32 studies were analyzed. The overall detection rate of any AF was 11.5% (95% confidence interval, 8.9%–14.3%), although the timing, duration, method of monitoring, and reporting of diagnostic criteria used for paroxysmal AF varied. Detection rates were higher in selected (13.4%; 95% confidence interval, 9.0%–18.4%) than in unselected patients (6.2%; 95% confidence interval, 4.4%–8.3%). There was substantial heterogeneity even within specified subgroups. Conclusions— Detection of AF was highly variable, and the review was limited by small sample sizes and marked heterogeneity. Further studies are required to inform patient selection, optimal timing, methods, and duration of monitoring for detection of AF/paroxysmal AF.

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.

Diagnosis of Stroke-Associated Pneumonia: Recommendations From the Pneumonia in Stroke Consensus Group

Background and Purpose— Lower respiratory tract infections frequently complicate stroke and adversely affect outcome. There is currently no agreed terminology or gold-standard diagnostic criteria for the spectrum of lower respiratory tract infections complicating stroke, which has implications for clinical practice and research. The aim of this consensus was to propose standardized terminology and operational diagnostic criteria for lower respiratory tract infections complicating acute stroke. Methods— Systematic literature searches of multiple electronic databases were undertaken. An evidence review and 2 rounds of consensus consultation were completed before a final consensus meeting in September 2014, held in Manchester, United Kingdom. Consensus was defined a priori as ≥75% agreement between the consensus group members. Results— Consensus was reached for the following: (1) stroke-associated pneumonia (SAP) is the recommended terminology for the spectrum of lower respiratory tract infections within the first 7 days after stroke onset; (2) modified Centers for Disease Control and Prevention (CDC) criteria are proposed for SAP as follows—probable SAP: CDC criteria met, but typical chest x-ray changes absent even after repeat or serial chest x-ray; definite SAP: CDC criteria met, including typical chest x-ray changes; (3) there is limited evidence for a diagnostic role of white blood cell count or C-reactive protein in SAP; and (4) there is insufficient evidence for the use of other biomarkers (eg, procalcitonin). Conclusions— Consensus operational criteria for the terminology and diagnosis of SAP are proposed based on the CDC criteria. These require prospective evaluation in patients with stroke to determine their reliability, validity, impact on clinician behaviors (including antibiotic prescribing), and clinical outcomes.

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.

C-reactive protein in intracerebral hemorrhage Time course, tissue localization, and prognosis

Objectives: We examined the C-reactive protein (CRP) response after spontaneous intracerebral hemorrhage (sICH) and its relationship to outcome. We additionally characterized early brain localization of CRP. Methods: In this prospective, multicenter, international, collaborative, longitudinal study with cross-sectional immunohistochemical analysis of brain tissue, 223 patients (M/F: 132/91) were recruited during the 2010 calendar year. CRP was evaluated at admission (median 93 minutes from symptom onset), 24 hours, 48 hours, and 72 hours after sICH. Brains of 5 subjects with sICH were compared to brains of 2 aged controls without evidence of brain pathology and 7 patients with ischemic stroke. Plasma CRP was measured over 72 hours following sICH and its relationship to 30-day mortality and functional outcome at 30 days (Glasgow Outcome Scale) was determined. CRP immunostaining patterns were analyzed in samples of sICH autopsy brains. Results: Plasma CRP increased over the 48 hours from admission and was significantly (p < 0.001) related to hematoma volume at later time points. The predictive utility of CRP for morbidity and mortality were maintained when adjusted for other risk factors and improved at 48 hours and 72 hours when compared with admission values. Although an early CRP localization was present in both ischemic and hemorrhagic lesions, an intense and diffuse neuropil staining was only present in sICH patients and particularly evident proximal to the hemorrhagic areas. Conclusions: Plasma CRP production increases markedly over the 48 hours to 72 hours period following sICH and is related to outcome. CRP is also present in large amounts around the hemorrhagic lesion and within neurons and glia of patients who died within 12 hours of sICH. Neurology® 2012;79:690–699