Inflammation, vasospasm, and brain injury after subarachnoid hemorrhage

Hypothesis on the Role of Cryptochromes in Inflammation and Subarachnoid Hemorrhage Outcome

We have recently found that the temperature variability (TV) in the day-night cycle may predict the mean intracranial pressure in the following 24 h (ICP₂₄) in subarachnoid hemorrhage (SAH) patients under multimodality monitoring, sedation, and hypothermia (<35°C). Specifically, we found that ICP₂₄ = 6 (4 - TV) mmHg. TV is the ratio between the coefficient of variation of temperature during the nocturnal and the preceding diurnal periods. This result suggests that the circadian clock reflects brain plasticity mechanisms and its malfunctioning leads to deterioration of the neurologic status. The sleep-wake cycle is absent in these patients and their circadian clock can function properly only by environment light-independent mechanisms. One mechanism involves the circadian clock proteins named cryptochromes (CRYs). CRYs are highly preserved and widespread in the evolutionary tree, are expressed in different cell types in humans [type II CRYs, in two forms: human cryptochrome 1 and 2 (hCRY1 and hCRY2)], and in certain species, respond to blue light and play role in magnetoreception. Interestingly, SAH outcome seems to correlate with inflammation, and CRYs decrease inflammatory activity. Our hypothesis derived from these observations is that CRYs modulate the circadian oscillation of temperature even during therapeutic hypothermia and improve outcome in SAH through decrease in inflammation. A strategy to test this hypothesis is to measure periodically during the acute phase of high-grade SAH the level of CRYs in cerebrospinal fluid (CSF) and circulating white blood cells, and to correlate these levels with outcome, TV, ICP₂₄, and pro- and anti-inflammatory markers in CSF and blood. If this hypothesis is true, the development of therapies targeting inflammation in SAH could take advantage of cryptochrome properties. It has been shown that blue light phototherapy increases the expression of CRYs in blood mononuclear cells in jaundiced neonates. Likewise, visual stimulus with flashing light improves Alzheimer's disease features in experimental model and there is a prominent expression of CRYs in the retina. Remarkably, recent evidence showed that hCRY2 responds to electromagnetic fields, which could be one elusive mechanism of action of transcranial magnetic stimulation and a reason for its use in SAH.

Elevated Systemic IL-6 Levels in Patients with Aneurysmal Subarachnoid Hemorrhage Is an Unspecific Marker for Post-SAH Complications

Background: Aneurysmal subarachnoid hemorrhage (aSAH) is still a fatal and morbid disease, although bleeding aneurysms can be secured in almost all cases. Occurrence of post-SAH complications including cerebral vasospasm, delayed cerebral ischemia, hydrocephalus, epilepsy, and infections are the main determinants of clinical outcome. Hence, it is important to search for early predictors for specific post-SAH complications to treat these complications properly. Both cellular and molecular (cytokines) inflammation play a key role after aSAH during the phase of occurrence of post-SAH complications. Interleukin-6 (IL-6) is a well-known cytokine that has been extensively analyzed in cerebrospinal fluid (CSF) of patients after aSAH, but detailed studies exploring the role of systemic IL-6 in aSAH associated complications and its impact on early clinical outcome prediction are lacking. The current study aims to analyze the systemic IL-6 levels over two weeks after bleeding and its role in post-SAH complications. Methods: We recruited 80 aSAH patients prospectively who underwent peripheral venous blood withdrawal in serum gel tubes. The blood was centrifuged to harvest the serum, which was immediately frozen at −80 °C until analysis. Serum IL-6 levels were quantified using Immulite immunoassay system. Patient records including age, gender, post-SAH complications, aneurysm treatment, and clinical outcome (modified Rankin scale and Glasgow outcome scale) were retrieved to allow different subgroup analysis. Results: Serum IL-6 levels were significantly raised after aSAH compared to healthy controls over the first two weeks after hemorrhage. Serum IL-6 levels were found to be significantly elevated in aSAH patients presenting with higher Hunt and Hess grades, increasing age, and both intraventricular and intracerebral hemorrhage. Interestingly, serum IL-6 was also significantly raised in aSAH patients who developed seizures, cerebral vasospasm (CVS), and chronic hydrocephalus. IL-6 levels were sensitive to the development of infections and showed an increase in patients who developed pneumoniae. Intriguingly, we found a delayed increase in serum IL-6 in patients developing cerebral infarction. Finally, IL-6 levels were significantly higher in patients presenting with poor clinical outcome in comparison to good clinical outcome at discharge from hospital. Conclusion: Serum IL-6 levels were elevated early after aSAH and remained high over the two weeks after initial bleeding. Serum IL-6 was elevated in different aSAH associated complications, acting as a non-specific marker for post-SAH complications and an important biomarker for clinical outcome at discharge.

AG490 ameliorates early brain injury via inhibition of JAK2/STAT3-mediated regulation of HMGB1 in subarachnoid hemorrhage

High mobility group box 1 (HMGB1) is a classic damage-associated molecular pattern that has an important role in the pathological inflammatory response. In vitro studies have demonstrated that the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is involved in the regulation of HMGB1 expression, mediating the inflammatory response. Therefore, the purpose of the present study was to evaluate JAK2/STAT3 pathway involvement in the subarachnoid hemorrhage (SAH)-dependent regulation of HMGB1, using an in vivo rat model. A SAH model was established by endovascular perforation. Western blotting, immunohistochemistry and immunofluorescence were used to analyze HMGB1 expression after SAH. In addition, the effects of AG490 after SAH on JAK2/STAT3 phosphorylation, HMGB1 expression and brain damage were evaluated. The results of the present study demonstrated that JAK2/STAT3 was significantly phosphorylated (P<0.05) and the total HMGB1 protein level was significantly increased (P<0.05) after SAH. In addition, the cytosolic HMGB1 level after SAH demonstrated an initial increase followed by a decrease to the control level, while the nuclear HMGB1 level after SAH demonstrated the opposite trend, with an initial decrease and subsequent increase. AG490 administration after SAH significantly inhibited JAK2/STAT3 phosphorylation (P<0.05), suppressed the expression and translocation of HMGB1, reduced cortical apoptosis, brain edema and neurological deficits. These results demonstrated the involvement of the JAK2/STAT3 pathway in HMGB1 regulation after SAH.

Inhibition of leukotriene B4 synthesis protects against early brain injury possibly via reducing the neutrophil-generated inflammatory response and oxidative stress after subarachnoid hemorrhage in rats

Leukotriene B4 (LTB4) is a highly potent neutrophil chemoattractant and neutrophils induces inflammatory response and oxidative stress when they recruit to and infiltrate in the injuried/inflamed site, such as the brain parenchyma after aneurysmal subarachnoid hemorrhage (SAH). This study is to investigate the potential effects of inhibition of LTB4 synthesis on neutrophil recruitment, inflammatory response and oxidative stress, as well as early brain injury (EBI) in rats after SAH. A pre-chiasmatic cistern SAH model of rats was used in this experiment. SC 57461A was used to inhibit LTB4 synthesis via intracerebroventricular injection. The brain tissues of temporal lobe after SAH were analyzed. Neuronal injury, brain edema and neurological function were evaluated to investigate the development of EBI. We found that inhibition of LTB4 synthesis after SAH could reduce the level of myeloperoxidase, alleviate the inflammatory response and oxidative stress, and reduce neuronal death in the brain parenchyma, and ameliorate brain edema and neurological behavior impairment at 24h after SAH. These results suggest that inhibition of LTB4 synthesis might alleviate EBI after SAH possibly via reducing the neutrophil-generated inflammatory response and oxidative stress.

Neurobehavioral testing in subarachnoid hemorrhage: A review of methods and current findings in rodents

The most important aspect of a preclinical study seeking to develop a novel therapy for neurological diseases is whether the therapy produces any clinically relevant functional recovery. For this purpose, neurobehavioral tests are commonly used to evaluate the neuroprotective efficacy of treatments in a wide array of cerebrovascular diseases and neurotrauma. Their use, however, has been limited in experimental subarachnoid hemorrhage studies. After several randomized, double-blinded, controlled clinical trials repeatedly failed to produce a benefit in functional outcome despite some improvement in angiographic vasospasm, more rigorous methods of neurobehavioral testing became critical to provide a more comprehensive evaluation of the functional efficacy of proposed treatments. While several subarachnoid hemorrhage studies have incorporated an array of neurobehavioral assays, a standardized methodology has not been agreed upon. Here, we review neurobehavioral tests for rodents and their potential application to subarachnoid hemorrhage studies. Developing a standardized neurobehavioral testing regimen in rodent studies of subarachnoid hemorrhage would allow for better comparison of results between laboratories and a better prediction of what interventions would produce functional benefits in humans.

Effect of Progesterone on Cerebral Vasospasm and Neurobehavioral Outcomes in a Rodent Model of Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) induces widespread inflammation leading to cellular injury, vasospasm, and ischemia. Evidence suggests that progesterone (PROG) can improve functional recovery in acute brain injury owing to its anti-inflammatory and neuroprotective properties, which could also be beneficial in SAH. We hypothesized that PROG treatment attenuates inflammation-mediated cerebral vasospasm and microglial activation, improves synaptic connectivity, and ameliorates functional recovery after SAH.

METHODS

We investigated the effect of PROG in a cisternal SAH model in adult male C57BL/6 mice. Neurobehavioral outcomes were evaluated using rotarod latency and grip strength tests. Basilar artery perimeter, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptor 1 (GluR1)/synaptophysin colocalization, and Iba-1 immunoreactivity were quantified histologically.

RESULTS

PROG (8 mg/kg) significantly improved rotarod latency at day 6 and grip strength at day 9. PROG-treated mice had significantly reduced basilar artery vasospasm at 24 hours. GluR1/synaptophysin colocalization, indicative of synaptic GluR1, was significantly reduced in the SAH+Vehicle group at 24 hours, and PROG treatment significantly attenuated this reduction. PROG treatment significantly reduced microglial cell activation and proliferation in cerebellum and cortex but not in the brainstem at 10 days.

CONCLUSIONS

PROG treatment ameliorated cerebral vasospasm, reduced microglial activation, restored synaptic GluR1 localization, and improved neurobehavioral performance in a murine model of SAH. These results provide a rationale for further translational testing of PROG therapy in SAH.

Cerebrospinal Fluid and Microdialysis Cytokines in Aneurysmal Subarachnoid Hemorrhage: A Scoping Systematic Review

Objective

To perform two scoping systematic reviews of the literature on cytokine measurement in cerebral microdialysis (CMD) and cerebrospinal fluid (CSF) in aneurysmal subarachnoid hemorrhage (SAH) patients, aiming to summarize the evidence relating cytokine levels to pathophysiology, disease progression, and outcome.

Methods

Two separate systematic reviews were conducted: one for CMD cytokines and the second for CSF cytokines.

Data sources

Articles from MEDLINE, BIOSIS, EMBASE, Global Health, Scopus, Cochrane Library (inception to October 2016), reference lists of relevant articles, and gray literature were searched.

Study selection

Two reviewers independently identified all manuscripts utilizing predefined inclusion/exclusion criteria. A two-tier filter of references was conducted.

Data extraction

Patient demographic and study data were extracted to tables.

Results

There were 9 studies identified describing the analysis of cytokines via CMD in 246 aneurysmal SAH patients. Similarly, 20 studies were identified describing the analysis of CSF cytokines in 630 patients. The two scoping systematic reviews demonstrated the following: (1) limited literature available on CMD cytokine measurement in aneurysmal SAH with some preliminary data supporting feasibility of measurement and potential association between interleukin (IL)-6 and patient outcome. (2) Various CSF measured cytokines may be associated with patient outcome at 3–6 months, including IL-1ra, IL-6, IL-8, and tumor necrosis factor-alpha. (3) There is a small literature body supporting an association between acute/subacute CSF transforming growth factor levels and the development of chronic hydrocephalus at 2–3 months.

Conclusion

The evaluation of CMD and CSF cytokines is an emerging area of the literature in aneurysmal SAH. Further large prospective multicenter studies on cytokines in CMD and CSF need to be conducted.

Role of Interleukin-10 in Acute Brain Injuries

Interleukin-10 (IL-10) is an important anti-inflammatory cytokine expressed in response to brain injury, where it facilitates the resolution of inflammatory cascades, which if prolonged causes secondary brain damage. Here, we comprehensively review the current knowledge regarding the role of IL-10 in modulating outcomes following acute brain injury, including traumatic brain injury (TBI) and the various stroke subtypes. The vascular endothelium is closely tied to the pathophysiology of these neurological disorders and research has demonstrated clear vascular endothelial protective properties for IL-10. In vitro and in vivo models of ischemic stroke have convincingly directly and indirectly shown IL-10-mediated neuroprotection; although clinically, the role of IL-10 in predicting risk and outcomes is less clear. Comparatively, conclusive studies investigating the contribution of IL-10 in subarachnoid hemorrhage are lacking. Weak indirect evidence supporting the protective role of IL-10 in preclinical models of intracerebral hemorrhage exists; however, in the limited number of clinical studies, higher IL-10 levels seen post-ictus have been associated with worse outcomes. Similarly, preclinical TBI models have suggested a neuroprotective role for IL-10; although, controversy exists among the several clinical studies. In summary, while IL-10 is consistently elevated following acute brain injury, the effect of IL-10 appears to be pathology dependent, and preclinical and clinical studies often paradoxically yield opposite results. The pronounced and potent effects of IL-10 in the resolution of inflammation and inconsistency in the literature regarding the contribution of IL-10 in the setting of acute brain injury warrant further rigorously controlled and targeted investigation.

Aneurysmal subarachnoid hemorrhage lead to systemic upregulation of IL-23/IL-17 inflammatory axis

IL-23 and IL-17 are pro-inflammatory cytokines. IL-23 is secreted by activated macrophages and dendritic cells, while IL-17 by Th17 cells. Serum IL-23 and IL-17 are known to be elevated in numerous inflammatory diseases including neurodegenerative diseases. The role of serum IL-23 and IL-17 in aneurysmal subarachnoid hemorrhage (aSAH) has still not been investigated. The present work investigates the serum IL-23 and IL-17 levels and their association with post hemorrhagic complications and clinical outcome in patients with aSAH.

METHODS

In this study, 80 patients with aSAH (Hunt and Hess grade I-V) were prospectively recruited. We enrolled 24 control patients with lumbar spinal stenosis. Peripheral venous blood was withdrawn from controls and from aSAH patients at day 1 and day 7, allowed to clot and centrifuged to obtain serum. Enzyme linked immunoassay kits were employed to quantify the serum levels of IL-23 and IL-17 by applying 50µL of serum samples. Post hemorrhagic complications and clinical outcome were documented prospectively from patient's hospital record.

RESULTS

Serum IL-23 and IL-17 levels were significantly elevated in aSAH patients at day 1 and day 7 (n=80) as compared to control patients (n=24). Further analysis after dichotomy of patients who suffered from post hemorrhagic complications including cerebral vasospasm, chronic hydrocephalus, seizures, cerebral ischemia, delayed neurological deficits showed differential correlations with different post hemorrhagic complications (Table 1). Serum IL-23 and IL-17 levels did not correlate with clinical outcome.

CONCLUSION

Serum IL-23 and IL-17 levels were elevated in patients with aSAH showing upregulation of IL-23/IL-17 inflammatory axis after aSAH. Serum IL-23 and IL-17 showed differential correlations with post hemorrhagic complications and no correlation with clinical outcome.

Roles of Pannexin-1 Channels in Inflammatory Response through the TLRs/NF-Kappa B Signaling Pathway Following Experimental Subarachnoid Hemorrhage in Rats

Background: Accumulating evidence suggests that neuroinflammation plays a critical role in early brain injury after subarachnoid hemorrhage (SAH). Pannexin-1 channels, as a member of gap junction proteins located on the plasma membrane, releases ATP, ions, second messengers, neurotransmitters, and molecules up to 1 kD into the extracellular space, when activated. Previous studies identified that the opening of Pannexin-1 channels is essential for cellular migration, apoptosis and especially inflammation, but its effects on inflammatory response in SAH model have not been explored yet.

Methods: Adult male Sprague-Dawley rats were divided into six groups: sham group (n = 20), SAH group (n = 20), SAH + LV-Scramble-ShRNA group (n = 20), SAH + LV-ShRNA-Panx1 group (n = 20), SAH + LV-NC group (n = 20), and SAH + LV-Panx1-EGFP group (n = 20). The rat SAH model was induced by injection of 0.3 ml fresh arterial, non-heparinized blood into the prechiasmatic cistern in 20 s. In SAH + LV-ShRNA-Panx1 group and SAH + LV-Panx1-EGFP group, lentivirus was administered via intracerebroventricular injection (i.c.v.) at 72 h before the induction of SAH. The Quantitative real-time polymerase chain reaction, electrophoretic mobility shift assay, enzyme-linked immunosorbent assay, immunofluorescence staining, and western blotting were performed to explore the potential interactive mechanism between Pannexin-1 channels and TLR2/TLR4/NF-κB-mediated signaling pathway. Cognitive and memory changes were investigated by the Morris water maze test.

Results: Administration with LV-ShRNA-Panx1 markedly decreased the expression levels of TLR2/4/NF-κB pathway-related agents in the brain cortex and significantly ameliorated neurological cognitive and memory deficits in this SAH model. On the contrary, administration of LV-Panx1-EGFP elevated the expressions of TLR2/4/NF-κB pathway-related agents, which correlated with augmented neuronal apoptosis.

Conclusion: Pannexin-1 channels may contribute to inflammatory response and neurobehavioral dysfunction through the TLR2/TLR4/NF-κB-mediated pathway signaling after SAH, suggesting a potential role of Pannexin-1 channels could be a potential therapeutic target for the treatment of SAH.

Early Diagnosis of Delayed Cerebral Ischemia: Possible Relevance for Inflammatory Biomarkers in Routine Clinical Practice?

BACKGROUND

Delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is one of the main causes of neurologic deterioration. However, it frequently evades timely detection. Early identification and effective reversal may improve the clinical outcome. In this prospective study, we evaluate several serum inflammatory markers after aneurysmal SAH with regard to the occurrence of DCI.

METHODS

On days 1, 4, 7, 10, and 14 after SAH, leucocyte count, C-reactive protein, interleukin 6, E-selectin, matrix metallopeptidase 9, intercellular adhesion molecule 1, and leukemia inhibitory factor were assessed in patients' serum samples. Using a Cox regression model (SPSS 21.0), associations of baseline parameters, maximum and delta (maximum minus baseline) values with occurrence of DCI were evaluated.

RESULTS

Considering the assessed parameters, leucocyte count (high baseline and delta values) matches most closely with occurrence of DCI. Although baseline levels of C-reactive protein are also associated with occurrence of DCI, neither maximum (only on a borderline level) nor delta levels do so.

CONCLUSIONS

Our data analysis identified leucocyte count as the parameter most likely associated with occurrence of DCI. However, because of its lack of specificity leucocyte count, it cannot be used as a biomarker. As hypothesized earlier, the results indicate a possible involvement of the inflammatory reaction after aneurysmal SAH in the pathomechanism of DCI.

Prediction of behavioural and cognitive deficits in patients with traumatic brain injury at an acute rehabilitation setting

OBJECTIVE

The goal of this study was to identify factors that would predict short-term neuropsychological outcome in patients with traumatic brain injury (TBI) hospitalized in an acute rehabilitation setting.

METHODS

Data was collected in the context of an acute early rehabilitation setting of a trauma centre. A brief neuropsychological assessment was carried out for 348 patients within a month following their trauma.

RESULTS

Length of post-traumatic amnesia (PTA) was the best predictor of behavioural, memory and executive function variables within a month post TBI. The odds of being agitated, labile, irritable and disinhibited at one month post trauma were almost six times higher for those with PTA that lasted more than 7 days compared to those with a PTA of less than 24 hours. Also, the odds of having a higher mental manipulation score (less significant executive function impairment) were almost two times lower for those with frontal lesions, and three to six times lower for those with PTA of more than 24 hours. In addition, TBI severity, education and age were considered good predictors of some aspects of neuropsychological outcome.

CONCLUSION

This model may help clinicians and administrators recognize the probable post-traumatic deficits as quickly as possible and to plan interventions as well as post-acute discharge orientation accordingly and early on.

Long-Lasting Cerebral Vasospasm, Microthrombosis, Apoptosis and Paravascular Alterations Associated with Neurological Deficits in a Mouse Model of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating disease with high mortality and morbidity. Long-term cognitive and sensorimotor deficits are serious complications following SAH but still not well explained and described in mouse preclinical models. The aim of our study is to characterize a well-mastered SAH murine model and to establish developing pathological mechanisms leading to cognitive and motor deficits, allowing identification of specific targets involved in these long-term troubles. We hereby demonstrate that the double blood injection model of SAH induced long-lasting large cerebral artery vasospasm (CVS), microthrombosis formation and cerebral brain damage including defect in potential paravascular diffusion. These neurobiological alterations appear to be associated with sensorimotor and cognitive dysfunctions mainly detected 10 days after the bleeding episode. In conclusion, this characterized model of SAH in mice, stressing prolonged neurobiological pathological mechanisms and associated sensitivomotor deficits, will constitute a validated preclinical model to better decipher the link between CVS, long-term cerebral apoptosis and cognitive disorders occurring during SAH and to allow investigating novel therapeutic approaches in transgenic mice.

Plasma Soluble Urokinase-Type Plasminogen Activator Receptor Is Not Associated with Neurological Outcome in Patients with Aneurysmal Subarachnoid Hemorrhage

Object

Aneurysmal subarachnoid hemorrhage (aSAH) is a common cause of death or long-term disability. Despite advances in neurocritical care, there is still only a very limited ability to monitor the development of secondary brain injury or to predict neurological outcome after aSAH. Soluble urokinase-type plasminogen activator receptor (suPAR) has shown potential as a prognostic and as an inflammatory biomarker in a wide range of critical illnesses since it displays an association with overall immune system activation. This is the first time that suPAR has been evaluated as a prognostic biomarker in aSAH.

Methods

In this prospective population-based study, plasma suPAR levels were measured in aSAH patients (n = 47) for up to 5 days. suPAR was measured at 0, 12, and 24 h after patient admission to the intensive care unit (ICU) and daily thereafter until he/she was transferred from the ICU. The patients’ neurological outcome was evaluated with the modified Rankin Scale (mRS) at 6 months after aSAH.

Results

suPAR levels (n = 47) during the first 24 h after aSAH were comparable in groups with a favorable (mRS 0–2) or an unfavorable (mRS 3–6) outcome. suPAR levels during the first 24 h were not associated with the findings in the primary brain CT, with acute hydrocephalus, or with antimicrobial medication use during 5-days’ follow-up. suPAR levels were associated with generally accepted inflammatory biomarkers (C-reactive protein, leukocyte count).

Conclusion

Plasma suPAR level was not associated with either neurological outcome or selected clinical conditions. While suPAR is a promising biomarker for prognostication in several conditions requiring intensive care, it did not reveal any value as a prognostic biomarker after aSAH.

An introduction to the pathophysiology of aneurysmal subarachnoid hemorrhage

Pathophysiological processes following subarachnoid hemorrhage (SAH) present survivors of the initial bleeding with a high risk of morbidity and mortality during the course of the disease. As angiographic vasospasm is strongly associated with delayed cerebral ischemia (DCI) and clinical outcome, clinical trials in the last few decades focused on prevention of these angiographic spasms. Despite all efforts, no new pharmacological agents have shown to improve patient outcome. As such, it has become clear that our understanding of the pathophysiology of SAH is incomplete and we need to reevaluate our concepts on the complex pathophysiological process following SAH. Angiographic vasospasm is probably important. However, a unifying theory for the pathophysiological changes following SAH has yet not been described. Some of these changes may be causally connected or present themselves as an epiphenomenon of an associated process. A causal connection between DCI and early brain injury (EBI) would mean that future therapies should address EBI more specifically. If the mechanisms following SAH display no causal pathophysiological connection but are rather evoked by the subarachnoid blood and its degradation production, multiple treatment strategies addressing the different pathophysiological mechanisms are required. The discrepancy between experimental and clinical SAH could be one reason for unsuccessful translational results.

Cytotoxic Lesions of the Corpus Callosum That Show Restricted Diffusion: Mechanisms, Causes, and Manifestations

Cytotoxic lesions of the corpus callosum (CLOCCs) are secondary lesions associated with various entities. CLOCCs have been found in association with drug therapy, malignancy, infection, subarachnoid hemorrhage, metabolic disorders, trauma, and other entities. In all of these conditions, cell-cytokine interactions lead to markedly increased levels of cytokines and extracellular glutamate. Ultimately, this cascade can lead to dysfunction of the callosal neurons and microglia. Cytotoxic edema develops as water becomes trapped in these cells. On diffusion-weighted magnetic resonance (MR) images, CLOCCs manifest as areas of low diffusion. CLOCCs lack enhancement on contrast material-enhanced images, tend to be midline, and are relatively symmetric. The involvement of the corpus callosum typically shows one of three patterns: (a) a small round or oval lesion located in the center of the splenium, (b) a lesion centered in the splenium but extending through the callosal fibers laterally into the adjacent white matter, or (c) a lesion centered posteriorly but extending into the anterior corpus callosum. CLOCCs are frequently but not invariably reversible. Their pathologic mechanisms are discussed, the typical MR imaging findings are described, and typical cases of CLOCCs are presented. Although CLOCCs are nonspecific with regard to the underlying cause, additional imaging findings and the clinical findings can aid in making a specific diagnosis. Radiologists should be familiar with the imaging appearance of CLOCCs to avoid a misdiagnosis of ischemia. When CLOCCs are found, the underlying cause of the lesion should be sought and addressed. ^©RSNA, 2017 An earlier incorrect version of this article appeared online. This article was corrected on February 13, 2017.

The effect of subarachnoid erythrocyte lysate on brain injury: a preliminary study

We found that more severe brain injury was caused by subarachnoid erythrocyte lysate, and inflammation associated with Prx2 might be involved in mechanism of brain injury.

Abundant erythrocytes remain and lyse partially in the subarachnoid space after severe subarachnoid haemorrhage (SAH). But the effect of subarachnoid erythrocyte lysate on brain injury is still not completely clear. In this study, autologous erythrocytes (the non-lysate group) and their lysate (the lysate group) were injected separately into the cistern magna of rabbits to induce a model of experimental SAH, although the control group received isotonic sodium chloride solution instead of erythrocyte solution. Results showed that vasospasm of the basilar artery was observed at 72 h after experimental SAH, but there was no significant difference between the non-lysate group and the lysate group. Brain injury was more severe in the lysate group than in the non-lysate group. Meanwhile, the levels of peroxiredoxin 2 (Prx2), IL-6 and TNF-α in brain cortex and in CSF were significantly higher in the lysate group than those in the non-lysate group. These results demonstrated that brain injury was more likely to be caused by erythrocyte lysate than by intact erythrocytes in subarachnoid space, and inflammation response positively correlated with Prx2 expression might be involved in mechanism of brain injury after SAH.

Elevated Baseline C-Reactive Protein as a Predictor of Outcome After Aneurysmal Subarachnoid Hemorrhage: Data From the Simvastatin in Aneurysmal Subarachnoid Hemorrhage (STASH) Trial

There remains a proportion of patients with unfavorable outcomes after aneurysmal subarachnoid hemorrhage, of particular relevance in those who present with a good clinical grade. A forewarning of those at risk provides an opportunity towards more intensive monitoring, investigation, and prophylactic treatment prior to the clinical manifestation of advancing cerebral injury.

miRNA expression profiling of cerebrospinal fluid in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE MicroRNAs (miRNAs) regulate gene expression and therefore play important roles in many physiological and pathological processes. The aim of this pilot study was to determine the feasibility of extraction and subsequent profiling of miRNA from CSF samples in a pilot population of aneurysmal subarachnoid hemorrhage patients and establish if there is a distinct CSF miRNA signature between patients who develop cerebral vasospasm and those who do not. METHODS CSF samples were taken at various time points during the clinical management of a subset of SAH patients (SAH patient samples without vasospasm, n = 10; SAH patient samples with vasospasm, n = 10). CSF obtained from 4 patients without SAH was also included in the analysis. The miRNA was subsequently isolated and purified and then analyzed on an nCounter instrument using the Human V2 and V3 miRNA assay kits. The data were imported into the nSolver software package for differential miRNA expression analysis. RESULTS From a total of 800 miRNAs that could be detected with each version of the miRNA assay kit, a total of 691 miRNAs were communal to both kits. There were 36 individual miRNAs that were differentially expressed (p < 0.01) based on group analyses, with a number of miRNAs showing significant changes in more than one group analysis. The changes largely reflected differences between non-SAH and SAH groups. These included miR-204-5p, miR-223-3p, miR-337-5p, miR-451a, miR-489, miR-508-3p, miR-514-3p, miR-516-5p, miR-548 m, miR-599, miR-937, miR-1224-3p, and miR-1301. However, a number of miRNAs did exclusively differ between the vasospasm and nonvasospasm SAH groups including miR-27a-3p, miR-516a-5p, miR-566, and miR-1197. CONCLUSIONS The findings indicate that temporal miRNA profiling can detect differences between CSF from aneurysmal SAH and non-SAH patients. Moreover, the miRNA profile of CSF samples from patients who develop cerebral vasopasm may be distinguishable from those who do not. These results provide a foundation for future research at identifying novel CSF biomarkers that might predispose to the development of cerebral vasospasm after SAH and therefore influence subsequent clinical management.

Aneurysmal Subarachnoid Hemorrhage and Neuroinflammation: A Comprehensive Review

Aneurysmal subarachnoid hemorrhage (SAH) can lead to devastating outcomes including vasospasm, cognitive decline, and even death. Currently, treatment options are limited for this potentially life threatening injury. Recent evidence suggests that neuroinflammation plays a critical role in injury expansion and brain damage. Red blood cell breakdown products can lead to the release of inflammatory cytokines that trigger vasospasm and tissue injury. Preclinical models have been used successfully to improve understanding about neuroinflammation following aneurysmal rupture. The focus of this review is to provide an overview of how neuroinflammation relates to secondary outcomes such as vasospasm after aneurysmal rupture and to critically discuss pharmaceutical agents that warrant further investigation for the treatment of subarachnoid hemorrhage. We provide a concise overview of the neuroinflammatory pathways that are upregulated following aneurysmal rupture and how these pathways correlate to long-term outcomes. Treatment of aneurysm rupture is limited and few pharmaceutical drugs are available. Through improved understanding of biochemical mechanisms of injury, novel treatment solutions are being developed that target neuroinflammation. In the final sections of this review, we highlight a few of these novel treatment approaches and emphasize why targeting neuroinflammation following aneurysmal subarachnoid hemorrhage may improve patient care. We encourage ongoing research into the pathophysiology of aneurysmal subarachnoid hemorrhage, especially in regards to neuroinflammatory cascades and the translation to randomized clinical trials.

MABS: targeted therapy tailored to the patient's need

Monoclonal antibodies (MABs) represent the window of opportunity in modern medicine. As immunology plays a vital role both in our survival and in disease development, MABs were found to be of great help in diagnosing, prognosticating and managing certain malignancies, inflammatory conditions, autoimmune as well as infectious diseases. Technological advances have enabled the production of MABs that target specific antigens linked with several disease processes. These drugs are now a component of therapy, not only for many common malignancies, including breast, colorectal, lung and pancreatic cancers, as well as lymphoma, leukaemia and multiple myeloma, but also for several inflammatory conditions such as rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis and inflammatory bowel disease. Targeted therapy has raised new questions about tailoring treatment, including cancer management, to the individual patient's needs. This would have a positive impact on the drug's effectiveness and toxicity as well as the economics of care. While targeted MABs are generally better tolerated than traditional chemotherapy, they are associated with several adverse effects, which vary from one patient to another.

Sex Differences in the Formation of Intracranial Aneurysms and Incidence and Outcome of Subarachnoid Hemorrhage: Review of Experimental and Human Studies

Intracranial aneurysms are defined as pathological dilatations of cerebral arteries and rupture of intracranial aneurysms leads to subarachnoid hemorrhage (SAH). The goal of this review was to outline the sex differences in the formation and progression of intracranial aneurysms as well as sex-related differences in incidence and outcome of SAH. The literature review was performed using PubMed with a combination of these search terms: "subarachnoid hemorrhage," "incidence," "outcome," "sex," "gender," "male," "female," "experimental," "mice," and "rats." Studies written in English were used. Female sex is thought to be a risk factor for aneurysm formation, especially in postmenopausal age populations, suggesting the potential protective involvement of sex steroids. Female sex is also considered a risk factor for SAH occurrence. Although incidence and mortality are confirmed to be higher in females in most studies, they elucidated no clear differences in the functional outcome among SAH survivors. The effect of gender on the pathophysiology of SAH is not very well understood; nevertheless, the majority of pre-clinical studies suggest a beneficial effect of sex steroids in experimental SAH. Moreover, conflicting results exist on the role and effect of hormone replacement therapies and oral contraceptive pills on the incidence and outcome of human SAH. Sex differences exist in the formation of aneurysms as well as the incidence and mortality of SAH. Potential therapeutic effects of sex steroids have been replicated in many animal studies, but their potential use in the treatment of acute SAH in human populations needs more future study.

Protective effects of Ephedra sinica extract on blood-brain barrier integrity and neurological function correlate with complement C3 reduction after subarachnoid hemorrhage in rats

Early brain injury, which is associated with brain cell death, blood-brain barrier disruption, brain edema, and other pathophysiological events, is thought to be the main target in the prevention of poor outcomes after subarachnoid hemorrhage (SAH). Emerging evidences indicates that complement system, especially complement C3 is detrimental to neurological outcomes of SAH patients. Recently, Ephedra sinica extract was extracted and purified, which exhibits ability to block the activity of the classical and alternative pathways of complement, and improve neurological outcomes after spinal cord injury and ischemic brain injury. However, it is still unclear whether Ephedra sinica extract could attenuate early brain injury after SAH. In the present study, a standard endovascular perforation model was used to produce the experimental SAH in Sprague-Dawley rats. Ephedra sinica extract (15mg/kg) was orally administrated daily and evaluated for effects on modified Garcia score, brain water content, Evans blue extravasation and fluorescence, cortex cell death by TUNEL staining, and the expressions of complement C3/C3b, activated C3, sonic hedgehog, osteopontin and matrix metalloproteinase-9 by western bolt and immunofluorescence staining. We founded that the Ephedra sinica extract alleviated the blood-brain barrier disruption and brain edema, eventually improved neurological functions after SAH in rats. These neuroprotective effects was associated with the inhibition of complement C3, possibly via upregulating sonic hedgehog and osteopontin signal, and reducing the expressions of matrix metalloproteinase-9. Taking together, these observations suggested complement C3 inhibition by the Ephedra sinica extract may be a protective factor against early brain injury after SAH.

Intraventricular fibrinolysis with tissue plasminogen activator is associated with transient cerebrospinal fluid inflammation: a randomized controlled trial

Locally administered tissue plasminogen activator (TPA) accelerates clearance of intraventricular hemorrhage (IVH), but its impact on neurologic outcomes remains unclear and preclinical research suggests it may have pro-inflammatory effects. We randomly allocated patients with ruptured cerebral aneurysms and IVH, treated with endovascular coiling and ventricular drainage, to receive either 2-mg intraventricular TPA or placebo every 12 hours. Cerebrospinal fluid (CSF) and serum cytokine and white blood cell (WBC) concentrations were measured before drug administration and daily for 72 hours. Cerebrospinal fluid D-dimer levels were assessed 6 and 12 hours after administration to quantify fibrinolysis. Six patients were randomized to each group. Patients treated with TPA developed higher CSF cytokine concentrations compared with placebo-treated patients (P<0.05 for tumor necrosis factor-α, interferon-γ, interleukin (IL)-1α, IL-1β, IL-2, IL-4, and IL-6), as well as higher CSF WBC counts (P=0.03). Differences were greatest after 24 hours and decreased over 48 to 72 hours. The magnitude of the inflammatory response was significantly associated with peak CSF D-dimer concentration and extent of IVH clearance. We conclude that intraventricular TPA administration produces a transient local inflammatory response, the severity of which is strongly associated with the degree of fibrinolysis, suggesting it may be induced by release of hematoma breakdown products, rather than the drug itself.

Hydrogen Sulfide Ameliorates Early Brain Injury Following Subarachnoid Hemorrhage in Rats

Increasing studies have demonstrated the neuroprotective effect of hydrogen sulfide (H2S) in central nervous system (CNS) diseases. However, the potential application value of H2S in the therapy of subarachnoid hemorrhage (SAH) is still not well known. This study was to investigate the potential effect of H2S on early brain injury (EBI) induced by SAH and explore the underlying mechanisms. The role of sodium hydrosulfide (NaHS), a donor of H2S, in SAH-induced EBI, was investigated in both in vivo and in vitro. A prechiasmatic cistern single injection model was used to produce experimental SAH in vivo. In vitro, cultured primary rat cortical neurons and human umbilical vein endothelial cells (HUVECs) were exposed to OxyHb at concentration of 10 μM to mimic SAH. Endogenous production of H2S in the brain was significantly inhibited by SAH. The protein levels of the predominant H2S-generating enzymes in the brain, including cystathionineb-synthase (CBS) and 3-mercaptopyruvate sulfur transferase (3MST), were also correspondingly reduced by SAH, while treatment with NaHS restored H2S production and the expressions of CBS and 3MST. More importantly, NaHS treatment could significantly attenuate EBI (including brain edema, blood-brain barrier disruption, brain cell apoptosis, inflammatory response, and cerebral vasospasm) after SAH. In vitro, H2S protects neurons and endothelial function by functioning as an antioxidant and antiapoptotic mediator. Our results suggest that NaSH as an exogenous H2S donor could significantly reduce EBI induced by SAH.

Memantine Attenuates Delayed Vasospasm after Experimental Subarachnoid Hemorrhage via Modulating Endothelial Nitric Oxide Synthase

Delayed cerebral vasospasm is an important pathological feature of subarachnoid hemorrhage (SAH). The cause of vasospasm is multifactorial. Impairs nitric oxide availability and endothelial nitric oxide synthase (eNOS) dysfunction has been reported to underlie vasospasm. Memantine, a low-affinity uncompetitive N-methyl-d-aspartate (NMDA) blocker has been proven to reduce early brain injury after SAH. This study investigated the effect of memantine on attenuation of vasospasm and restoring eNOS functionality. Male Sprague-Dawley rats weighing 350–450 g were randomly divided into three weight-matched groups, sham surgery, SAH + vehicle, and SAH + memantine groups. The effects of memantine on SAH were evaluated by assessing the severity of vasospasm and the expression of eNOS. Memantine effectively ameliorated cerebral vasospasm by restoring eNOS functionality. Memantine can prevent vasospasm in experimental SAH. Treatment strategies may help combat SAH-induced vasospasm in the future.

Neuroprotective properties of dehydroepiandrosterone-sulfate and its relationship to interleukin 6 after aneurysmal subarachnoid hemorrhage: a prospective cohort study

INTRODUCTION

The established neuroprotective property of the sex steroid precursor dehydroepiandrosterone-sulfate (DHEAS) has not yet been investigated in the context of aneurysmal subarachnoid hemorrhage (aSAH). The influence of DHEAS on inflammatory response resulting in modulation of interleukin 6 (IL-6) synthesis has been shown. Here, we evaluate DHEAS serum levels after aSAH (day 0-14) and levels of IL-6 related to functional outcome at discharge and at six months.

METHODS

A complete data set (DHEAS and IL-6 serum levels for days 0, 1, 4, 7, 10 and 14 after aSAH) and outcome assessment at discharge according to modified Rankin Scale score (mRS) was available for 53 patients of the initially screened cohort (n = 109). Outcome assessment six months after aSAH was obtained from 41 patients. Logarithmized levels of DHEAS and IL-6 were related to dichotomized functional outcome either assessed at discharge or at six months. A mixed between-within subjects ANOVA was applied for statistical analysis (SPSS 21.0).

RESULTS

DHEAS and IL-6 levels across time were related to functional outcome. Regarding outcome assessment at discharge and at six months after aSAH, DHEAS levels (transformed to square root for statistical purposes) were considerably higher in patients with favorable outcome (mRS 0-2) (p = .001; p = .020). Inversely, in patients with favorable outcome either at discharge or six months after aSAH, lower IL-6 levels (logarithmized for statistical purposes) were observed across time (both p < .001).

CONCLUSION

We provide new evidence that DHEAS is associated with protective properties resulting in improvement of functional outcome after aSAH, possibly by influencing the inflammatory response after aSAH shown in the decreasing IL-6 serum levels. But the results for outcome six months after SAH are limited due to a high drop-out rate.

Immune cells subpopulations in cerebrospinal fluid and peripheral blood of patients with Aneurysmal Subarachnoid Hemorrhage

Background

There is growing evidence supporting the role of inflammation in aneurysmal subarachnoid hemorrhage (aSAH) pathophysiology and it is of great interest to elucidate which immune mechanisms are involved.

Methods

12 aSAH patients and 28 healthy controls were enrolled prospectively. We assessed leukocytes subpopulations and their activation status by flow cytometry in cerebrospinal fluid (CSF) and peripheral blood (PB) of SAH patients at the same time and in PB of controls.

Results

Monocytes and neutrophils were activated in CSF of aSAH patients. The percentage of CD14⁺⁺CD16⁺ monocytes were higher in CSF than in PB of aSAH patients, and were also increased in PB of aSAH patients compared with controls. An enhanced expression of CD69 was shown in CSF neutrophils compared with PB in aSAH patients. PB of aSAH patients showed lower percentage of total lymphocytes compared with controls PB. Additionally, lymphocytes were activated in CSF and PB of aSAH patients. CD4⁺ and CD8⁺ T cells had a decreased expression on CD3 and higher levels of CD69 in CSF compared with PB in aSAH patients. Moreover, PB CD4⁺ and CD8⁺ T cells of aSAH patients were activated compared with controls. Additionally, CD28 expression was decreased on CSF T lymphocytes.

Conclusions

Our data suggest an important recruitment of leukocytes to the site of injury in aSAH as well as an increased activation at this level. Overall, these results indicate that aSAH probably stimulates both the innate and adaptive immune responses.

VAP-1 blockade prevents subarachnoid hemorrhage-associated cerebrovascular dilating dysfunction via repression of a neutrophil recruitment-related mechanism

Our previous findings indicated that in rats subjected to subarachnoid hemorrhage (SAH), suppression of post-SAH neuroinflammation via vascular adhesion protein-1 (VAP-1) blockade provides significant neuroprotection. We and others have reported that neuroinflammation contributes to cerebral microvascular impairment. Thus, in the present study, we tested the hypotheses that: (1) treatment with LJP-1586, a selective VAP-1 blocker, prevents SAH-associated pial arteriolar dilating dysfunction; and (2) the vasculoprotective effect of LJP-1586 arises from inhibiting SAH-elicited neutrophil recruitment. We utilized an endovascular perforation model of SAH. Rats subjected to SAH were either treated with LJP-1586 or rendered neutropenic via anti-neutrophil-antibody treatment. Findings from these groups were compared to their respective control groups. At 48 h post-SAH, rats were evaluated for neurobehavioral function, pial venular leukocyte trafficking, and pial arteriolar reactivity to topically-applied acetylcholine (ACh) and S-nitroso-N-acetyl penicillamine (SNAP). Pial arteriolar responses decreased at 48 h post-SAH. However, in the presence of LJP-1586, those responses were significantly preserved. Neutrophil-depletion yielded a substantial suppression of SAH-associated leukocyte adhesion and infiltration. This was accompanied by a significant preservation of pial arteriolar dilating function, suggesting a direct link between neutrophil recruitment and the loss of cerebral microvascular reactivity. Moreover, neutrophil depletion also was associated with significant protection of neurobehavioral function. The present findings suggest that attenuating SAH-linked elevation in neutrophil trafficking will protect against the development of microvascular dysfunction and subsequent neurological impairment.