Ischemic stroke patients are prone to infection by stroke-induced immunodepression. We hypothesized that levels of lipopolysaccharide binding protein (LBP), interleukin-10 (IL-10), IL-6 and C-reactive protein (CRP) are early predictors for the development of stroke-associated infection. Fifty-six patients with ischemic stroke (n = 51) and transient ischemic attack (TIA) (n = 5) who presented within 6 hours after symptom onset and who were free of detectable infection on admission were included in the study. Of these, 20 developed early infections during the first week. Blood samples were taken at 6, 12, and 24 hours and at 3 and 7 days after stroke onset. Levels of LBP, Il-10, IL-6 and CRP, as well as S100B, were measured as markers of inflammation and brain damage by commercially available immunometric tests. In the univariate analysis, levels of LBP, IL-10, IL-6 and CRP significantly differed between patients who developed an infection and those who did not. In the binary logistic regression analysis, which was adjusted for National Institutes of Health Stroke Scale (NIHSS) on admission, stroke subtype and S100B peak levels, as indicator of the extent of brain damage, IL-10 at 6 hours, CRP at 6 hours and NIHSS on admission were identified as independent predictors of infection (IL-10: P = 0.009; CRP: P = 0.018; NIHSS: P = 0.041). The area under the curve (AUC) of the receiver operating characteristic (ROC) curves in relation to the dichotomized status of the infection (infection versus no infection) was 0.74 (95% confidence interval: 0.59 to 0.88) for CRP at 6 hours, 0.76 (0.61 to 0.9) for IL-10 at 6 hours, 0.83 (0.71 to 0.94) for NIHSS on admission and 0.94 (0.88 to 1) for the combination of CRP, IL-10 and NIHSS. In a subanalysis, 16 patients with early infections were matched with 16 patients without infection according to S100B peak levels. Here, the temporal pattern of LBP, IL-10, IL-6 and CRP significantly differed between the patient groups. Our data show that blood levels of inflammation markers may be used as early predictors of stroke-associated infection. We propose prospective studies to investigate if the calculated cut-offs of CRP, IL-10 and NIHSS might help to identify patients who should receive early preventive antibiotic treatment.

Background and Purpose: Cell-free DNA (cfDNA) and endogenous deoxyribonuclease activity are opposing mediators and might influence the inflammatory response following acute ischemic stroke. In this cohort study, we investigated the relation between these markers, circulating inflammatory mediators and clinical course including occurrence of stroke-associated infections (SAI) in patients with acute stroke. Methods: Ninety-two patients with stroke due to large vessel occlusion undergoing mechanical thrombectomy were prospectively recruited at Hannover Medical School from March 2018 to August 2019. Deoxyribonuclease activity, cfDNA, damage-associated molecular patterns, and circulating cytokines were measured in venous blood collected immediately before mechanical thrombectomy and 7 days later. Reperfusion status was categorized (sufficient/insufficient). Clinical outcome was evaluated using the modified Rankin Scale after 90 days, where a score of 3 to 6 was considered unfavorable. To validate findings regarding SAI, another stroke cohort (n=92) was considered with blood taken within 24 hours after stroke onset. Results: Patients with unfavorable clinical outcome had higher cfDNA concentrations. After adjustment for confounders (Essen Stroke Risk Score, National Institutes of Health Stroke Scale, and sex), 7-day cfDNA was independently associated with clinical outcome and especially mortality (adjusted odds ratio: 3.485 [95% CI, 1.001–12.134] and adjusted odds ratio: 9.585 [95% CI, 2.006–45.790]). No association was found between reperfusion status and cfDNA or deoxyribonuclease activity. While cfDNA concentrations correlated positively, deoxyribonuclease activity inversely correlated with distinct biomarkers. Baseline deoxyribonuclease activity was lower in patients who developed SAI compared with patients without SAI. This association was confirmed after adjustment for confounding factors (adjusted odds ratio: 0.447 [95% CI, 0.237–0.844]). In cohort 2, differences of deoxyribonuclease activity between patients with and without SAI tended to be higher with higher stroke severity. Conclusions: The interplay of endogenous deoxyribonuclease activity and cfDNA in acute stroke entails interesting novel diagnostic and potential therapeutic approaches. We confirm an independent association of cfDNA with a detrimental clinical course after stroke due to large vessel occlusion. This study provides first evidence for lower endogenous deoxyribonuclease activity as risk factor for SAI after severe stroke. Download figure Download PowerPoint

Carotid stenosis (CS) is an important cause of ischemic stroke. However, reliable markers for the purpose of identification of high-risk, so-called vulnerable carotid plaques, are still lacking. Monocyte subsets are crucial players in atherosclerosis and might also contribute to plaque rupture. In this study we, therefore, aimed to investigate the potential role of monocyte subsets and associated chemokines as clinical biomarkers for vulnerability of CS. Patients with symptomatic and asymptomatic CS (n = 21), patients with cardioembolic ischemic strokes (n = 11), and controls without any cardiovascular disorder (n = 11) were examined. Cardiovascular risk was quantified using the Essen Stroke Risk Score (ESRS). Monocyte subsets in peripheral blood were measured by quantitative flow cytometry. Plaque specimens were histologically analyzed. Furthermore, plasma levels of monocyte chemotactic protein 1 (MCP-1) and fractalkine were measured. Intermediate monocytes (Mon2) were significantly elevated in symptomatic and asymptomatic CS-patients compared to controls. Mon2 counts positively correlated with the ESRS. Moreover, stroke patients showed an elevation of Mon2 compared to controls, independent of the ESRS. MCP-1 levels were significantly higher in patients with symptomatic than in those with asymptomatic CS. Several histological criteria significantly differed between symptomatic and asymptomatic plaques. However, there was no association of monocyte subsets or chemokines with histological features of plaque vulnerability. Due to the multifactorial influence on monocyte subsets, the usability as clinical markers for plaque vulnerability seems to be limited. However, monocyte subsets may be critically involved in the pathology of CS.

The chemokine fractalkine (CX3CL1, FKN) is involved in neural-microglial interactions and is regarded as neuroprotective according to several in vivo studies of inflammatory and degenerative states of the brain. Recently, an association with outcome in human ischemic stroke has been proposed. In this study, we aimed to investigate the temporal pattern of FKN levels in acute ischemic stroke in relation to stroke severity and outcome.

Background Endovascular treatment improves outcome in patients with acute ischaemic stroke due to large vessel occlusion in general. But outcome in some of these patients is jeopardized by recanalization failure or bleeding. Objectives This study aimed to determine a possible association of mediators of inflammation and haemostasis (C-reactive protein, interleukin-6, matrix metalloproteinase-9, monocyte chemoattractant protein-1, asymmetric dimethylarginine [ADMA], symmetric dimethylarginine, von Willebrand factor and a disintegrin and metalloproteinase with a thrombospondin type 1 motif 13 [ADAMTS-13]) with the post-intervention grade of reperfusion, complications and clinical outcome in patients who underwent endovascular treatment of ischaemic stroke. Patients/Methods Forty-one patients with acute ischaemic stroke due to large vessel occlusion were prospectively enrolled into the study. Peripheral venous blood was taken prior to treatment and 24 hours and 3, 7 and 90 days after symptom onset. The post-intervention grade of reperfusion was determined using the modified Treatment in Cerebral Infarction (mTICI) score. Clinical outcome on day 90 was assessed using the modified Rankin's scale (mRS). Results Low ADAMTS-13 activity ( p =0.009) and missing of statin therapy ( p =0.038) on admission were independently associated with unfavourable outcome (mRS: 5-6). Patients with unsuccessful reperfusion (mTICI: 0-1) showed higher ADMA levels on admission ( p =0.018). However, this association could not be confirmed in the binary logistic regression analysis. Conclusion Low ADAMTS-13 activity is a predictor of unfavourable outcome in patients with ischaemic stroke undergoing endovascular therapy. Further studies are warranted to elucidate the clinical and potential therapeutic role of ADAMTS-13 in acute ischaemic stroke.

: Inflammation including immunothrombosis by neutrophil extracellular traps (NETs) has important implications in acute ischemic stroke and can affect reperfusion status, susceptibility to stroke associated infections (SAI) as well as functional clinical outcome. NETs were shown to be prevalent in stroke thrombi and NET associated markers were found in stroke patients’ blood. However, little is known whether blood derived NET markers reflect the amount of NETs in thrombi. Conclusions from blood derived markers to thrombus composition might open avenues for novel strategies in diagnostic and therapeutic approaches. We prospectively recruited 166 patients with acute ischemic stroke undergoing mechanical thrombectomy between March 2018 and May 2021. Available thrombi (n = 106) were stained for NET markers DNA-histone-1 complexes and myeloperoxidase (MPO). Cell free DNA (cfDNA), deoxyribonuclease (DNase) activity, MPO-histone complexes and a cytokine-panel were measured before thrombectomy and after seven days. Clinical data, including stroke etiology, reperfusion status, SAI and functional outcome after rehabilitation, were collected of all patients. NET markers were present in all thrombi. At onset the median concentration of cfDNA in blood was 0.19 µg/ml increasing to 0.30 µg/ml at 7 days. Median DNase activity at onset was 4.33 pmol/min/ml increasing to 4.96 pmol/min/ml at 7 days. Within thrombi DNA-histone-1 complexes and MPO correlated with each other (ρ = 0.792; p < 0.001). Moreover, our study provides evidence for an association between the amount of NETs and endogenous DNase activity in blood with amounts of NETs in cerebral thrombi. However, these associations need to be confirmed in larger cohorts, to investigate the potential clinical implications for individualized therapeutic and diagnostic approaches in acute ischemic stroke. Graphical Abstract