Linking infection and inflammation in acute ischemic stroke

Prediction of upcoming urinary tract infection after intracerebral hemorrhage: a machine learning approach based on statistics collected at multiple time points

Purpose

Accurate prediction of urinary tract infection (UTI) following intracerebral hemorrhage (ICH) can significantly facilitate both timely medical interventions and therapeutic decisions in neurocritical care. Our study aimed to propose a machine learning method to predict an upcoming UTI by using multi-time-point statistics.

Methods

A total of 110 patients were identified from a neuro-intensive care unit in this research. Laboratory test results at two time points were chosen: Lab 1 collected at the time of admission and Lab 2 collected at the time of 48 h after admission. Univariate analysis was performed to investigate if there were statistical differences between the UTI group and the non-UTI group. Machine learning models were built with various combinations of selected features and evaluated with accuracy (ACC), sensitivity, specificity, and area under the curve (AUC) values.

Results

Corticosteroid usage (p < 0.001) and daily urinary volume (p < 0.001) were statistically significant risk factors for UTI. Moreover, there were statistical differences in laboratory test results between the UTI group and the non-UTI group at the two time points, as suggested by the univariate analysis. Among the machine learning models, the one incorporating clinical information and the rate of change in laboratory parameters outperformed the others. This model achieved ACC = 0.773, sensitivity = 0.785, specificity = 0.762, and AUC = 0.868 during training and 0.682, 0.685, 0.673, and 0.751 in the model test, respectively.

Conclusion

The combination of clinical information and multi-time-point laboratory data can effectively predict upcoming UTIs after ICH in neurocritical care.

Effects of body mass index on the immune response within the first days after major stroke in humans

INTRODUCTION

Immunological alterations associated with increased susceptibility to infection are an essential aspect of stroke pathophysiology. Several immunological functions of adipose tissue are altered by obesity and are accompanied by chronic immune activation. The purpose of this study was to examine immune function (monocytes, granulocytes, cytokines) as a function of body mass index (BMI: 1st group: 25; 2nd group: 25 BMI 30; 3rd group: 30) and changes in body weight post stroke.

METHOD

Fat status was assessed using standardized weight measurements on days 1, 2, 3, 4, 5, and 7 after ischemic stroke in a cohort of 40 stroke patients and 16 control patients. Liver fat and visceral fat were assessed by MRI on day 1 or 2 [I] and on day 5 or 7 [II]. Leukocyte subpopulations in peripheral blood, cytokines, chemokines, and adipokine concentrations in sera were quantified. In a second cohort (stroke and control group, n = 17), multiple regression analysis was used to identify correlations between BMI and monocyte and granulocyte subpopulations.

RESULTS

Weight and fat loss occurred from the day of admission to day 1 after stroke without further reduction in the postischemic course. No significant changes in liver or visceral fat were observed between MRI I and MRI II. BMI was inversely associated with IL-6 levels, while proinflammatory cytokines such as eotaxin, IFN-β, IFN -γ and TNF-α were upregulated when BMI increased. The numbers of anti-inflammatory CD14+CD16+ monocytes and CD16+CD62L- granulocytes were reduced in patients with higher BMI values, while that of proinflammatory CD16dimCD62L+ granulocytes was increased.

CONCLUSION

A small weight loss in stroke patients was detectable. The data demonstrate a positive correlation between BMI and a proinflammatory poststroke immune response. This provides a potential link to how obesity may affect the clinical outcome of stroke patients.

Impact of early urinary catheter removal on successful voiding and physical function in stroke patients

OBJECTIVE

The aim of the present study was to identify factors related to the success of trial without catheter (TWOC) in patients with stroke and to examine the effect of the timing of urinary catheter removal on the course of stroke.

METHODS

Patients who were admitted to the Stroke Care Unit of our institution between March 2018 and October 2021 were included. To identify factors related to success of TWOC, a multivariate analysis was performed on the patient's condition at admission and catheter indwelling time. The patients were divided into two groups by the timing of catheter removal, and we assessed the relationship between the timing of catheter removal successful TWOC and recovery of physical function.

RESULTS

A total of 118 patients were included. The presence of comorbidities and scores of severity and function at admission were not predictors of successful voiding. The time to achieve voiding sussess was significantly shorter in the early catheter removal group than in the later group (p<0.005). Interestingly, the early group also showed better improvements in physical function.

CONCLUSION

Early removal of catheters may lead to early recovery of bladder function, improvement of physical function, and lower risk of complications in patients with stroke. J. Med. Invest. 70 : 436-442, August, 2023.

Association of White Blood Cell Count With Clinical Outcome Independent of Treatment With Alteplase in Acute Ischemic Stroke

Introduction

Higher white blood cell (WBC) count is associated with poor functional outcome in acute ischemic stroke (AIS). However, little is known about whether the association is modified by treatment with intravenous alteplase.

Methods

WAKE-UP was a randomized controlled trial of the efficacy and safety of magnetic resonance imaging [MRI]-based thrombolysis in unknown onset stroke. WBC count was measured on admission and again at 22–36 h after randomization to treatment (follow-up). Favorable outcome was defined by a score of 0 or 1 on the modified Rankin scale (mRS) 90 days after stroke. Further outcome were stroke volume and any hemorrhagic transformation (HT) that were assessed on follow-up CT or MRI. Multiple logistic regression analysis was used to assess the association between outcome and WBC count and treatment group.

Results

Of 503 randomized patients, WBC count and baseline parameters were available in 437 patients (μ = 64.7 years, 35.2% women) on admission and 355 patients (μ = 65.1 years, 34.1% women) on follow-up. Median WBC count on admission was 7.6 × 10⁹/L (interquartile range, IQR, 6.1–9.4 × 10⁹/L) and 8.2 × 10⁹/L (IQR, 6.7–9.7 × 10⁹/L) on follow-up. Higher WBC count both on admission and follow-up was associated with lower odds of favorable outcome, adjusted for age, National Institutes of Health (NIH) Stroke Scale Score, temperature, and treatment (alteplase vs. placebo, adjusted odds ratio, aOR 0.85, 95% confidence interval [CI] 0.78–0.94 and aOR 0.88, 95% CI 0.79–0.97). No interaction between WBC count and treatment group was observed (p = 0.11). Furthermore, WBC count on admission and follow-up was significantly associated with HT (aOR 1.14, 95% CI 1.05–1.24 and aOR 1.13, 95% CI 1.00–1.26). Finally, WBC count on follow-up was associated with larger stroke volume (aOR 2.57, 95% CI 1.08–6.07).

Conclusion

Higher WBC count is associated with unfavorable outcome, an increased risk of HT, and larger stroke volume, independent of treatment with alteplase. Whether immunomodulatory manipulation of WBC count improves stroke outcome needs to be tested.

Trial Registration

ClinicalTrials.gov Identifier: NCT01525290.

Endogenous Deoxyribonuclease Activity and Cell-Free Deoxyribonucleic Acid in Acute Ischemic Stroke: A Cohort Study

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.

Neutrophil-Related Ratios Predict the 90-Day Outcome in Acute Ischemic Stroke Patients After Intravenous Thrombolysis

Background and Purpose

Mounting researches have illuminated that the neutrophil-related ratios were related to the prognosis of acute ischemic stroke (AIS). However, few have compared their predictive value and accuracy. To make such comparison and identify the best indicator on the 90-day outcome, we investigated biomarkers including neutrophil ratio (Nr), neutrophil count (Nc), lymphocyte (L), neutrophil-to-lymphocyte ratio (NLR), platelet (P or PLT), platelet-to-neutrophil ratio (PNR), NLR-to-platelet ratio (NLR/PLT), eosinophil (E), neutrophil-to-eosinophil ratio (NER), monocyte (M), and monocyte-to-neutrophil ratio (MNR).

Methods

This retrospective study recruited 283 AIS and 872 healthy controls (HCs) receiving intravenous thrombolysis (IVT). Blood samples were collected after 24 h of admission before IVT. Propensity Score Matching (PSM) was used to explore whether these ratios differentiated AIS and HCs. We applied univariate and multivariate analyses to evaluate the prediction effect of these ratios separately or added in the model and figured out a clinical prediction model. To estimate the discrimination and calibration of the new models, the receiver operating characteristics (ROC) curve analysis, DeLong method, and likelihood ratio test (LR test) were utilized.

Results

PSM showed that Nr, Nc, NLR, P, PNR, NLR/PLT, NER, and MNR facilitates the differentiation of the HCs and AIS. Among the eight biomarkers, PNR and MNR could differentiate the 90-day outcome, and it was found out that PNR performed better. Univariate regression analysis demonstrated that PNR was the only independent predictor which needs no adjustment. Besides, the multivariate regression analysis, Delong method, and LR test indicated that among the neutrophil-related ratios, NLR, PNR, NLR/PLT, NER, and MNR exerted little influence on the discrimination but could enhance the calibration of the base model, and NER proved to work best.

Conclusion

Low PNR was the best indicator among the neutrophil-related ratios tin predicting a poor 90-day outcome of AIS patients. Moreover, high NER performed best when predicting the 90-day outcome to improve the calibration of the base model.

Is neutrophil/eosinophil ratio at admission a prognostic marker for in-hospital mortality of acute ischemic stroke?

OBJECTIVES

There has been a recent focus on hematological parameters affecting the prognosis of acute ischemic stroke (AIS). However, there are no studies investigating the neutrophil/eosinophil ratio (NER). This study aimed to investigate whether NER at admission is a prognostic marker for in-hospital mortality in patients with AIS.

METHODS

204 AIS patients with similar vascular occlusion were included in the study, including 135 patients who survived and 69 patients who died in the hospital. Multivariate logistic regression analysis was performed to investigate the prognostic factors of AIS. The receiver operating characteristics (ROC) curve analysis was used to evaluate the predictive value of the variables and calculate the cut-off values.

RESULTS

69 patients died in the hospital [24 men and 45 women, median age: 78 (49-99)], and 135 patients survived [58 men and 77 women, median age: 74 (22-99)]. The mean age of patients with mortality was higher compared to the patients who survived (p value=0.007). Multivariate logistic regression model revealed that only NER and red blood cell distribution width (RDW-SD) were prognostic factors (p = 0.036 and p = 0.032, respectively). Areas under the ROC curve were 0.675 for NER (95% CI, 0.59-0.75), 0.636 for neutrophil (95% CI, 0.55-0.71), 0.602 for RDW-SD (95% CI, 0.51-0.69) and 0.656 for eosinophil (95% CI, 0.57-0.74).

CONCLUSION

Our results showed that there is a correlation between the in-hospital mortality of AIS and high NER at admission. NER at admission can be used as a poor prognostic marker for AIS.

Leukocyte Count and Adverse Clinical Outcomes in Acute Ischemic Stroke Patients

Background: Post-ischemic inflammatory response might be affected by many factors. We chose leukocyte count as a marker of inflammatory response and investigated whether the effects of leukocyte count on the clinical outcomes in acute ischemic stroke patients are different according to different factors.

Methods: We derived data from the China National Stroke Registry II. Patients with ischemic stroke were classified into four groups by leukocyte count quartiles within the first 24 h after admission. Adverse clinical outcomes were defined as recurrent stroke, all-cause death, and poor functional outcomes (3 ≤ mRS ≤ 5) at 3-months and 1-year follow-up. The subgroup factors were age, sex, history of hypertension, history of diabetes, history of previous stroke, or transient ischemic attack and smoking status. We assessed the association between leukocyte count and adverse clinical outcomes and evaluated this association in different subgroups.

Results: A total of 14,678 patients were included. Patients in higher quartiles were likely to be younger, male, smokers, and drinkers, and to have a shorter time from symptom onset to arrival, a more proportion of history of diabetes, atrial fibrillation, and hypertension, and a higher severity of stroke. Higher quartiles were associated with elevated risk of adverse clinical outcomes at 3-months and 1-year follow-up. Leukocyte count had a moderate accuracy to predict clinical outcomes. There was no difference in the relationship between leukocyte count and adverse clinical outcomes across subgroups such as age, sex, history of hypertension, and smoking. The effect of leukocyte count on all-cause death was pronounced among patients with previous stroke or transient ischemic attack, and the effect of leukocyte count on short-term poor functional outcomes was also pronounced among patients without diabetes.

Conclusions: Leukocyte count is associated with short-term and long-term clinical outcomes of acute ischemic stroke and may have predictive value, especially in patients with certain specific characteristics.

Peri-Infarct Upregulation of the Oxytocin Receptor in Vascular Dementia

Vascular dementia (VaD) is cognitive decline linked to reduced cerebral blood perfusion, yet there are few therapeutic options to protect cognitive function following cerebrovascular accidents. The purpose of this study was to profile gene expression changes unique to VaD to identify and characterize disease relevant changes that could offer clues for future therapeutic direction. Microarray-based profiling and validation studies of postmortem frontal cortex samples from VaD, Alzheimer disease, and age-matched control subjects revealed that the oxytocin receptor (OXTR) was strongly and differentially upregulated in VaD. Further characterization in fixed tissue from the same cases showed that OXTR upregulation occurs de novo around and within microinfarcts in peri-infarct reactive astrocytes as well as within vascular profiles, likely on microvascular endothelial cells. These results indicate that increased OXTR expression in peri-infarct regions may be a specific response to microvascular insults. Given the established OXTR signaling cascades that elicit antioxidant, anti-inflammatory, and pro-angiogenic responses, the present findings suggest that de novo OXTR expression in the peri-infarct space is a tissue-protective response by astroglial and vascular cells in the wake of ischemic damage that could be exploited as a therapeutic option for the preservation of cognition following cerebrovascular insults.

Clinical determination of serum nardilysin levels in predicting 30-day mortality among adults with malignant cerebral infarction

BACKGROUND

Nardilysin, a kind of metalloendopeptidase, plays an important role in numerous inflammatory diseases. Malignant cerebral infarction (Glasgow coma scale score of <9) is associated with a high mortality risk. Here, we intended to investigate the relationship between serum nardilysin levels and prognosis of patients with malignant cerebral infarction.

METHODS

Serum nardilysin concentrations were quantified at malignant cerebral infarction diagnosis moment in 105 patients and at study entrance in 105 healthy controls. Association of nardilysin concentrations with 30-day mortality and overall survival was estimated using multivariate analyses.

RESULTS

The patients exhibited substantially increased serum nardilysin concentrations, as compared to the controls. Nardilysin concentrations were in pronounced correlation with Glasgow coma scale scores and serum C-reactive protein concentrations. Serum nardilysin was independently predictive of 30-day mortality and overall survival. Under receiver operating characteristic curve, its high discriminatory ability was found.

CONCLUSIONS

Rising serum nardilysin concentrations following malignant cerebral infarction are strongly related to stroke severity, inflammatory extent and a higher risk of mortality, substantializing serum nardilysin as a potential prognostic biomarker for malignant cerebral infarction.

The relationship among neutrophil to lymphocyte ratio, stroke territory, and 3-month mortality in patients with acute ischemic stroke

BACKGROUND

Stroke therapy options have focused on limiting the infarct volume. Neutrophil to lymphocyte ratio (NLR) can be valuable to detect the patients that required intensive treatment at early stage by predicting infarct volume. The aim of this study is to evaluate the relationship between NLR and infarct volume according to the stroke territory, and to determine the prognostic value of NLR for predicting 3-month mortality in acute ischemic stroke (AIS) patients.

METHODS

A total of 107 patients with AIS were enrolled and followed up 3 months in terms of mortality. Study population was divided into two groups according to the stroke territory: anterior circulating stroke (ACS) and posterior circulating stroke (PCS). All patients underwent magnetic resonance imaging. The complete blood count and venous blood samples were obtained from the patients on admission to the emergency department.

RESULTS

There were no difference between ACS and PCS groups regarding baseline characteristics and co-morbid diseases. Also, C-reactive protein and NLR were similar between two groups. In correlation analyses, infarct volume was significantly correlated with CRP and NLR in ACS (r = 0.350, p = 0.001 and r = 0.482, p ≤ 0.001, respectively), but not correlated with infarct volume in PCS. Also, NLR was correlated with NIHHS in only ACS group (r = 0.326, p = 0.002). Multivariate analysis showed that NLR was the only independent predictor of 3-month mortality (OR 1.186, 95% CI 1.032-1.363, p = 0.016).

CONCLUSION

NLR is significantly correlated with ACS infarct volume, but not with PCS infarct volume in AIS. Also, NLR was an independent predictor of 3-month mortality in AIS patient.

Focal ischemic stroke leads to lung injury and reduces alveolar macrophage phagocytic capability in rats

BACKGROUND

Ischemic stroke causes brain inflammation, which we postulate may result in lung damage. Several studies have focused on stroke-induced immunosuppression and lung infection; however, the possibility that strokes may trigger lung inflammation has been overlooked. We hypothesized that even focal ischemic stroke might induce acute systemic and pulmonary inflammation, thus altering respiratory parameters, lung tissue integrity, and alveolar macrophage behavior.

METHODS

Forty-eight Wistar rats were randomly assigned to ischemic stroke (Stroke) or sham surgery (Sham). Lung function, histology, and inflammation in the lung, brain, bronchoalveolar lavage fluid (BALF), and circulating plasma were evaluated at 24 h. In vitro, alveolar macrophages from naïve rats (unstimulated) were exposed to serum or BALF from Sham or Stroke animals to elucidate possible mechanisms underlying alterations in alveolar macrophage phagocytic capability. Alveolar macrophages and epithelial and endothelial cells of Sham and Stroke animals were also isolated for evaluation of mRNA expression of interleukin (IL)-6 and tumor necrosis factor (TNF)-α.

RESULTS

Twenty-four hours following ischemic stroke, the tidal volume, expiratory time, and mean inspiratory flow were increased. Compared to Sham animals, the respiratory rate and duty cycle during spontaneous breathing were reduced, but this did not affect lung mechanics during mechanical ventilation. Lungs from Stroke animals showed clear evidence of increased diffuse alveolar damage, pulmonary edema, and inflammation markers. This was associated with an increase in ultrastructural damage, as evidenced by injury to type 2 pneumocytes and endothelial cells, cellular infiltration, and enlarged basement membrane thickness. Protein levels of proinflammatory mediators were documented in the lung, brain, and plasma (TNF-α and IL-6) and in BALF (TNF-α). The phagocytic ability of macrophages was significantly reduced. Unstimulated macrophages isolated from naïve rats only upregulated expression of TNF-α and IL-6 following exposure to serum from Stroke rats. Exposure to BALF from Stroke or Sham animals did not change alveolar macrophage behavior, or gene expression of TNF-α and IL-6. IL-6 expression was increased in macrophages and endothelial cells from Stroke animals.

CONCLUSIONS

In rats, focal ischemic stroke is associated with brain-lung crosstalk, leading to increased pulmonary damage and inflammation, as well as reduced alveolar macrophage phagocytic capability, which seems to be promoted by systemic inflammation.

Immunity and inflammation predictors for short-term outcome of stroke in young adults

BACKGROUND

The current study was conducted to identify independent predictors of severity and short-term outcome of first-ever ischemic stroke in young adults.

METHODS

We retrospectively enrolled 325 consecutive patients aged 18-49 years with first-ever ischemic stroke admitted to our center between April 2013 and June 2015. Variables were systematically registered and compared between patients with different neurological severity (mild stroke: National Institutes of Health Stroke Scale [NIHSS] ≤ 8 and severe stroke: >8) and different stroke outcome (favorable: modified Rankin scale score 0-2 and unfavorable: 3-5 or death) at 14 days after stroke onset.

RESULTS

A total of 325 patients fulfilled the inclusion criteria. There were 242 patients with mild stroke. They exhibited lower white blood cell (WBC), globulin, plasma glucose, fibrinogen (Fib) levels and higher albumin, albumin/globulin (A/G), free triiodothyronine (FT3) levels. Logistic regression analysis showed that FT3 (≧3.18) and WBC (≧7.1) were independent predictors. There were 122 patients demonstrating an unfavorable outcome. Higher WBC, globulin, plasma glucose and Fib levels, lower albumin, FT3, A/G levels, higher NIHSS score and longer hospital stay were significantly associated with unfavorable outcome. In the logistic regression model, we found that A/G (≧1.56), FT3 (≧4.09) and WBC (≧7.1) were independent predictors for short-term outcome.

CONCLUSIONS

Our data suggested that higher A/G, FT3 levels served as independent predictors of favorable outcome, and a higher FT3 value may also predict mild stroke, while higher WBC may predict a poor functional outcome and severe stroke in patients with acute ischemia.

Neutrophil-to-Lymphocyte Ratio Is a Prognostic Marker in Acute Ischemic Stroke

BACKGROUND

Neutrophil-to-lymphocyte ratio is an independent predictor of mortality in patients with acute ischemic stroke. However, it is uncertain whether neutrophil-to-lymphocyte ratio is related with functional outcome and recurrent ischemic stroke. In this study, we aimed to investigate the relationship of neutrophil-to-lymphocyte ratio with stroke severity, functional outcome, and recurrent ischemic stroke after acute ischemic stroke.

METHODS

A total of 280 patients with acute ischemic stroke were included in the study. Patients were divided into 3 groups according to the neutrophil-to-lymphocyte ratio value (<2, 2-3, >3). Demographic, clinical, and laboratory data were collected for all patients. We evaluated the association between neutrophil-to-lymphocyte ratio and (1) stroke severity on admission, (2) functional outcome at 3 months, and (3) recurrent ischemic stroke. Regression analyses were performed, adjusting for confounders.

RESULTS

After adjustment for potential confounders, neutrophil-to-lymphocyte ratio was associated with an increased risk of stroke severity on admission (odds ratio [OR] 1.364, 95% confidence interval [CI] 1.101-1.690, P = .005) and primary unfavorable outcome (OR 1.455, 95% CI 1.083-1.956, P = .013). After a median of 1.13 years (interquartile range.91-1.42) of follow-up, neutrophil-to-lymphocyte ratio was associated with recurrent ischemic stroke after adjustment (hazard ratio 1.499, 95% CI 1.161-1.935, P = .002).

CONCLUSIONS

Our study suggests that neutrophil-to-lymphocyte ratio is associated with stroke severity on admission, primary unfavorable functional outcome, and recurrent ischemic stroke in patients with acute ischemic stroke.

Individuality, phenotypic differentiation, dormancy and 'persistence' in culturable bacterial systems: commonalities shared by environmental, laboratory, and clinical microbiology

For bacteria, replication mainly involves growth by binary fission. However, in a very great many natural environments there are examples of phenotypically dormant, non-growing cells that do not replicate immediately and that are phenotypically 'nonculturable' on media that normally admit their growth. They thereby evade detection by conventional culture-based methods. Such dormant cells may also be observed in laboratory cultures and in clinical microbiology. They are usually more tolerant to stresses such as antibiotics, and in clinical microbiology they are typically referred to as 'persisters'. Bacterial cultures necessarily share a great deal of relatedness, and inclusive fitness theory implies that there are conceptual evolutionary advantages in trading a variation in growth rate against its mean, equivalent to hedging one's bets. There is much evidence that bacteria exploit this strategy widely. We here bring together data that show the commonality of these phenomena across environmental, laboratory and clinical microbiology. Considerable evidence, using methods similar to those common in environmental microbiology, now suggests that many supposedly non-communicable, chronic and inflammatory diseases are exacerbated (if not indeed largely caused) by the presence of dormant or persistent bacteria (the ability of whose components to cause inflammation is well known). This dormancy (and resuscitation therefrom) often reflects the extent of the availability of free iron. Together, these phenomena can provide a ready explanation for the continuing inflammation common to such chronic diseases and its correlation with iron dysregulation. This implies that measures designed to assess and to inhibit or remove such organisms (or their access to iron) might be of much therapeutic benefit.

Individuality, phenotypic differentiation, dormancy and 'persistence' in culturable bacterial systems: commonalities shared by environmental, laboratory, and clinical microbiology

For bacteria, replication mainly involves growth by binary fission. However, in a very great many natural environments there are examples of phenotypically dormant, non-growing cells that do not replicate immediately and that are phenotypically 'nonculturable' on media that normally admit their growth. They thereby evade detection by conventional culture-based methods. Such dormant cells may also be observed in laboratory cultures and in clinical microbiology. They are usually more tolerant to stresses such as antibiotics, and in clinical microbiology they are typically referred to as 'persisters'. Bacterial cultures necessarily share a great deal of relatedness, and inclusive fitness theory implies that there are conceptual evolutionary advantages in trading a variation in growth rate against its mean, equivalent to hedging one's bets. There is much evidence that bacteria exploit this strategy widely. We here bring together data that show the commonality of these phenomena across environmental, laboratory and clinical microbiology. Considerable evidence, using methods similar to those common in environmental microbiology, now suggests that many supposedly non-communicable, chronic and inflammatory diseases are exacerbated (if not indeed largely caused) by the presence of dormant or persistent bacteria (the ability of whose components to cause inflammation is well known). This dormancy (and resuscitation therefrom) often reflects the extent of the availability of free iron. Together, these phenomena can provide a ready explanation for the continuing inflammation common to such chronic diseases and its correlation with iron dysregulation. This implies that measures designed to assess and to inhibit or remove such organisms (or their access to iron) might be of much therapeutic benefit.

Lipopolysaccharide binding protein, interleukin-10, interleukin-6 and C-reactive protein blood levels in acute ischemic stroke patients with post-stroke infection

Background

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.

Methods

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.

Results

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.

Conclusions

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.

Could (18) F-DPA-714 PET imaging be interesting to use in the early post-stroke period?

Background

Cerebral stroke is a severe and frequent condition that requires rapid and reliable diagnosis. If administered shortly after the first symptoms manifest themselves, IV thrombolysis has been shown to increase the functional prognosis by restoring brain reperfusion. However, a better understanding of the pathophysiology of stroke should help to identify potential new therapeutic targets. Stroke is known to induce an inflammatory brain reaction that involves overexpression of the 18-kDa translocator protein (TSPO) in glial cells and infiltrated leukocytes, which can be visualised by positron emission tomography (PET). We aimed to evaluate post-stroke neuroinflammation using the PET TSPO radioligand ¹⁸ F-DPA-714.

Methods

Nine patients underwent ¹⁸ F-DPA-714 PET and magnetic resonance imaging (MRI) between 8 and 18 days after the ictus. Co-registration of MRI and PET images was used to define three volumes of interest (VOIs): core infarction, contralateral region, and cerebellum ipsilateral to the stroke lesion. Time activity curves were obtained from each VOI, and ratios of mean and maximum activities between the VOIs were calculated.

Results

We observed an increased uptake of ¹⁸ F-DPA-714 co-localised with the infarct tissue and extension beyond the region corresponding to the damage in the blood brain barrier. No correlation was identified between ¹⁸ F-DPA-714 uptake and infarct volume. ¹⁸ F-DPA-714 uptake in ischemic lesion (mainly associated with TSPO expression in the infarct area and in the surrounding neighbourhood) slowly decreased from 10 min pi to the end of the PET acquisition, remaining higher than that in both contralateral region and ipsilateral cerebellum.

Conclusion

Our results show that ¹⁸ F-DPA-714 uptake after acute ischemia is mainly associated with TSPO expression in the infarct area and in the surrounding neighbourhood. We also demonstrated that the kinetics of ¹⁸ F-DPA-714 differs in injured tissue compared to normal tissue. Therefore, ¹⁸ F-DPA-714 may be useful in assessing the extent of neuroinflammation associated with acute stroke and could also help to predict clinical outcomes and functional recovery, as well as to assess therapeutic strategies, such as the use of neuroprotective/anti-inflammatory drugs.

Body Temperature, Blood Infection Parameters, and Outcome of Thrombolysis-Treated Ischemic Stroke Patients

Background and Aims

Body temperature, inflammation, and infections may modify response to thrombolytic therapy. We studied their associations with clinical improvement after intravenous thrombolysis and three-month outcome.

Methods

We included 985 consecutive acute ischemic stroke patients treated with intravenous thrombolysis at the Helsinki University Central Hospital during 1995–2008. Body temperature, blood leukocyte count, and C-reactive protein levels were analyzed on arrival and at day one. Clinical improvement was defined as National Institutes of Health Stroke Scale score decrease of ≥4 points or a score of 0 at 24 h. Functional outcome was assessed at three-months with the modified Rankin Scale dichotomized at 0–2 (good) vs. 3–6 (poor). Associations were tested with multivariable logistic regression analysis.

Results

Of the baseline variables, lower C-reactive protein independently predicted clinical improvement at 24 h (odds ratio 0·94 per 5 mg/L; 95% confidence interval 0·89–1·00; P = 0·03), whereas higher leukocyte count (odds ratio 1·10 per E9/L; 1·03–1·17; P < 0·01) and C-reactive protein (odds ratio 1·07 per 5 mg/L; 1·01–1·14; P = 0·02) were associated with poor three-month outcome. When body temperature increased over the first 24 h, clinical improvement after thrombolysis was unlikely (odds ratio 0·66 per °C; 0·45–0·95; P = 0·03) and poor outcome more common (odds ratio 1·63 per °C; 1·24–2·14; P < 0·001). Elevated leukocytes at baseline increased the risk of symptomatic intracerebral hemorrhage (odds ratio 1·07 per E9/L; 1·00–1·13; P= 0·04).

Conclusion

A lower level of systemic inflammation at time of thrombolysis may be associated with clinical improvement and good outcome at three-months. Increase in body temperature during the first 24 h associates with lack of clinical improvement and worse patient outcome.

C-reactive protein is associated with the progression of acute embolic stroke in rabbit model

Several lines of evidence have shown that plasma C-reactive protein (CRP) is associated with increased risk of stroke; however, previous studies were not adequately powered to assess whether plasma CRP levels are associated with stroke progression. In the current study, we designed a rabbit stroke model and investigated the relationship between plasma CRP and infarcted brain tissue. To produce a rabbit stroke model, we injected autologous thrombi into the left internal carotid artery. The plasma CRP levels were measured by ELISA at 0.5, 3, 6, 9, and 12 h poststroke. At 12 h, the rabbits were sacrificed, and the whole brains were examined by H & E and immunohistochemical staining with a monoclonal antibody against rabbit CRP. CRP mRNA expression in the infarcted tissue was evaluated by RT-PCR. Plasma CRP was markedly increased after embolic stroke. Plasma CRP positively correlated with the cerebral infarct area (r = 0.98, P < 0.01). Immunohistochemical staining revealed that CRP was frequently present in the infarcted area but not in normal cerebral tissue. RT-PCR showed that CRP was expressed in infarcted brain tissue. The plasma CRP level was significantly elevated after stroke and was closely correlated with the size of infarction, suggesting that CRP is an ideal marker to assess the acute embolic stroke.

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

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

Effects of methylmercury on the secretion of pro-inflammatory cytokines from primary microglial cells and astrocytes

Glial cells, including oligodendrocytes, astrocytes and microglia are important to proper central nervous system (CNS) function. Deregulation or changes to CNS populations of astrocytes and microglia in particular are expected to play a role in many neurodegenerative diseases, including Parkinson's disease, amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD). Previous studies have reported methylmercury (MeHg) induced changes in glial cell function; however, the effects of MeHg on these cells remains poorly understood. This study aims to examine the effect of MeHg on the secretion of pro-inflammatory cytokines from microglia and astrocytes. The impact of the microglia/astrocyte ratio on cytokine secretion was also examined. Microglia and astrocytes were cultured from the brains of neo-natal BALB/C mice and dosed with MeHg (0-1 μM) and stimulated with PAM(3)CSK(4) (PAM(3)), a toll-like receptor (TLR) ligand. After this, the secretion of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and interleukin-1-beta (IL-1β) was measured by ELISA. MeHg reduced the secretion of IL-6 in a dose dependant manner but did not effect the secretion of TNF-α. No change in IL-1β was observed in any treatments, indicating that PAM(3) cannot induce the secretion of this cytokine from glial cells. Additionally, the ratio of microglia/astrocyte had an effect on the secretion of IL-6 but not TNF-α. These results indicate that MeHg can modify the response of glial cells and the interactions with astrocytes can affect the response of the microglia cells in culture. These results are significant in understanding the potential relationship with MeHg and neurodegenerative diseases and for the interpretation of results of future in vitro studies using monoculture.

Hypoxia in the regulation of neural stem cells

In aerobic organisms, oxygen is a critical factor in tissue and organ morphogenesis from embryonic development throughout post-natal life, as it regulates various intracellular pathways involved in cellular metabolism, proliferation, survival and fate. In the mammalian central nervous system, oxygen plays a critical role in regulating the growth and differentiation state of neural stem cells (NSCs), multipotent neuronal precursor cells that reside in a particular microenvironment called the neural stem cell niche and that, under certain physiological and pathological conditions, differentiate into fully functional mature neurons, even in adults. In both experimental and clinical settings, oxygen is one of the main factors influencing NSCs. In particular, the physiological condition of mild hypoxia (2.5-5.0% O(2)) typical of neural tissues promotes NSC self-renewal; it also favors the success of engraftment when in vitro-expanded NSCs are transplanted into brain of experimental animals. In this review, we analyze how O(2) and specifically hypoxia impact on NSC self-renewal, differentiation, maturation, and homing in various in vitro and in vivo settings, including cerebral ischemia, so as to define the O(2) conditions for successful cell replacement therapy in the treatment of brain injury and neurodegenerative diseases.

Activated leukocyte cell adhesion molecule and prognosis in acute ischemic stroke

BACKGROUND AND PURPOSE

Biomarkers predicting mortality and functional outcome in stroke may be clinically helpful in identification of patients likely to benefit from intervention. Activated leukocyte cell adhesion molecule (ALCAM) is upregulated during neuroinflammation; we investigated whether ALCAM concentrations are associated with long-term mortality after ischemic stroke.

METHODS

In 244 patients with acute ischemic stroke (age 69±13 years), samples of ALCAM were obtained serially from presentation to Day 5 and after 6 months. Patients with overt ischemic heart disease and atrial fibrillation were excluded. The patients were followed for 47 months with all-cause and cardiovascular mortality as end points.

RESULTS

At follow-up, 72 patients (29%) had died, 43 due to cardiovascular causes. Patients with ALCAM in the fourth quartile (>46.8 ng/mL) at admission had a significantly poorer survival rate on univariate analysis (P<0.001); other time points did not add further but provided similar prognostic information. In multivariate analysis, after adjustment for age, stroke severity, C-reactive protein levels, troponin T levels, and heart and/or renal failure, ALCAM levels above the fourth quartile remained an independent predictor of long-term mortality (adjusted hazard ratio, 2.05; 95% CI, 1.11 to 3.76; P=0.021) and cardiovascular mortality (adjusted hazard ratio, 2.54; 95% CI, 1.06 to 6.07; P=0.028).

CONCLUSIONS

ALCAM levels measured at admission of acute ischemic stroke are associated with long-term mortality.