Altered levels of transthyretin in human cerebral microdialysate after subarachnoid haemorrhage using proteomics; a descriptive pilot study

BACKGROUND

Subarachnoid haemorrhage (SAH) is one of the most severe forms of stroke in which delayed cerebral ischemia is one of the major complications. Neurointensive care aims at preventing and treating such complications and identification of biomarkers of early signs of ischemia might therefore be helpful.

METHODS

We aimed at describing proteome profile in cerebral microdialysate in four patients with aneurysmal SAH using two dimensional gel electrophoresis in combination with mass spectrometry in search for new biomarkers for delayed cerebral ischemia and to investigate if there were temporal fluctuations in those biomarkers over time after aneurysmal bleed.

RESULTS

The results showed transthyretin in nine different proteoforms (1001, 1102, 2101, 3101, 4101, 4102, 5001, 5101, 6101) in cerebral microdialysate samples from four patients having sustained SAH. Several proteoforms show highly differing levels and pooled analysis of all samples showed varying optical density related to time from aneurysmal bleed, indicating a temporal evolution.

CONCLUSIONS

Transthyretin proteoforms have not earlier been shown in cerebral microdialysate after SAH and we describe differing levels based on proteoform as well as time from subarachnoid bleed. Transthyretin is well known to be synthetized in choroid plexus, whilst intraparenchymal synthesis remains controversial. The results need to be confirmed in larger studies in order to further describe transthyretin.

Minocycline Attenuates Microglia/Macrophage Phagocytic Activity and Inhibits SAH-Induced Neuronal Cell Death and Inflammation

Background

Neuroprotective treatment strategies aiming at interfering with either inflammation or cell death indicate the importance of these mechanisms in the development of brain injury after subarachnoid hemorrhage (SAH). This study was undertaken to evaluate the influence of minocycline on microglia/macrophage cell activity and its neuroprotective and anti-inflammatory impact 14 days after aneurismal SAH in mice.

Methods

Endovascular filament perforation was used to induce SAH in mice. SAH + vehicle-operated mice were used as controls for SAH vehicle-treated mice and SAH + minocycline-treated mice. The drug administration started 4 h after SAH induction and was daily repeated until day 7 post SAH and continued until day 14 every second day. Brain cryosections were immunolabeled for Iba1 to detect microglia/macrophages and NeuN to visualize neurons. Phagocytosis assay was performed to determine the microglia/macrophage activity status. Apoptotic cells were stained using terminal deoxyuridine triphosphate nick end labeling. Real-time quantitative polymerase chain reaction was used to estimate cytokine gene expression.

Results

We observed a significantly reduced phagocytic activity of microglia/macrophages accompanied by a lowered spatial interaction with neurons and reduced neuronal apoptosis achieved by minocycline administration after SAH. Moreover, the SAH-induced overexpression of pro-inflammatory cytokines and neuronal cell death was markedly attenuated by the compound.

Conclusions

Minocycline treatment may be implicated as a therapeutic approach with long-term benefits in the management of secondary brain injury after SAH in a clinically relevant time window.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12028-022-01511-5.

Current Approaches to Monitor Macromolecules Directly from the Cerebral Interstitial Fluid

Gaining insights into the pharmacokinetic and pharmacodynamic properties of lead compounds is crucial during drug development processes. When it comes to the treatment of brain diseases, collecting information at the site of action is challenging. There are only a few techniques available that allow for the direct sampling from the cerebral interstitial space. This review concerns the applicability of microdialysis and other approaches, such as cerebral open flow microperfusion and electrochemical biosensors, to monitor macromolecules (neuropeptides, proteins, …) in the brain. Microdialysis and cerebral open flow microperfusion can also be used to locally apply molecules at the same time at the site of sampling. Innovations in the field are discussed, together with the pitfalls. Moreover, the ‘nuts and bolts’ of the techniques and the current research gaps are addressed. The implementation of these techniques could help to improve drug development of brain-targeted drugs.

Emerging Role of Microglia-Mediated Neuroinflammation in Epilepsy after Subarachnoid Hemorrhage

Epilepsy is a common and serious complication of subarachnoid hemorrhage (SAH), giving rise to increased morbidity and mortality. It's difficult to identify patients at high risk of epilepsy and the application of anti-epileptic drugs (AEDs) following SAH is a controversial topic. Therefore, it's pressingly needed to gain a better understanding of the risk factors, underlying mechanisms and the optimization of therapeutic strategies for epilepsy after SAH. Neuroinflammation, characterized by microglial activation and the release of inflammatory cytokines, has drawn growing attention due to its influence on patients with epilepsy after SAH. In this review, we discuss the risk factors for epilepsy after SAH and emphasize the critical role of microglia. Then we discuss how various molecules arising from pathophysiological changes after SAH activate specific receptors such as TLR4, NLRP3, RAGE, P2X7R and initiate the downstream inflammatory pathways. Additionally, we focus on the significant responses implicated in epilepsy including neuronal excitotoxicity, the disruption of blood-brain barrier (BBB) and the change of immune responses. As the application of AEDs for seizure prophylaxis after SAH remains controversial, the regulation of neuroinflammation targeting the key pathological molecules could be a promising therapeutic method. While neuroinflammation appears to contribute to epilepsy after SAH, more comprehensive experiments on their relationships are needed.

Update: Microdialysis for Monitoring Cerebral Metabolic Dysfunction after Subarachnoid Hemorrhage

Cerebral metabolic dysfunction has been shown to extensively mediate the pathophysiology of brain injury after subarachnoid hemorrhage (SAH). The characterization of the alterations of metabolites in the brain can help elucidate pathophysiological changes occurring throughout SAH and the relationship between secondary brain injury and cerebral energy dysfunction after SAH. Cerebral microdialysis (CMD) is a tool that can measure concentrations of multiple bioenergetics metabolites in brain interstitial fluid. This review aims to provide an update on the implication of CMD on the measurement of metabolic dysfunction in the brain after SAH. A literature review was conducted through a general PubMed search with the terms “Subarachnoid Hemorrhage AND Microdialysis” as well as a more targeted search using MeSh with the search terms “Subarachnoid hemorrhage AND Microdialysis AND Metabolism.” Both experimental and clinical papers were reviewed. CMD is a suitable tool that has been used for monitoring cerebral metabolic changes in various types of brain injury. Clinically, CMD data have shown the dramatic changes in cerebral metabolism after SAH, including glucose depletion, enhanced glycolysis, and suppressed oxidative phosphorylation. Experimental studies using CMD have demonstrated a similar pattern of cerebral metabolic dysfunction after SAH. The combination of CMD and other monitoring tools has also shown value in further dissecting and distinguishing alterations in different metabolic pathways after brain injury. Despite the lack of a standard procedure as well as the presence of limitations regarding CMD application and data interpretation for both clinical and experimental studies, emerging investigations have suggested that CMD is an effective way to monitor the changes of cerebral metabolic dysfunction after SAH in real-time, and alternatively, the combination of CMD and other monitoring tools might be able to further understand the relationship between cerebral metabolic dysfunction and brain injury after SAH, determine the severity of brain injury and predict the pathological progression and outcomes after SAH. More translational preclinical investigations and clinical validation may help to optimize CMD as a powerful tool in critical care and personalized medicine for patients with SAH.

Early matrix metalloproteinase-9 concentration in the first 48 h after aneurysmal subarachnoid haemorrhage predicts delayed cerebral ischaemia: An observational study

BACKGROUND

Delayed cerebral ischaemia from vasospasm is an important cause of complications and death after aneurysmal subarachnoid haemorrhage. There is currently no established biomarker for identifying patients at high risk of delayed cerebral ischaemia.

OBJECTIVE

Considering the important role of inflammation in the pathogenesis of delayed cerebral ischaemia, we investigated whether matrix metalloproteinase-9 (MMP-9) may be an efficient biomarker for predicting elayed cerebral ischaemia after subarachnoid haemorrhage.

DESIGN

Single-centre prospective observational study.

SETTING

Neuroscience Critical Care Unit of a teaching hospital.

PARTICIPANTS

Thirty consecutive patients with severe subarachnoid haemorrhage requiring external ventricular drainage were enrolled during 2013 and 2014.

INTERVENTIONS

Blood and cerebrospinal fluid (CSF) were sampled within the first 24 h and between 48 and 72 h after admission. We evaluated the activity and concentrations of MMP-9 and endothelin-1 with zymography and ELISA. Patients were allocated to groups with delayed cerebral ischaemia (n = 16) or without delayed cerebral ischaemia (n = 14).

RESULTS

Within 24 h, median [interquartile range] MMP-9 concentrations in CSF were significantly higher in patients with delayed cerebral ischaemia (47 [21 to 102] ng ml) than in those without delayed cerebral ischaemia (4 [2 to 13] ng ml, P = 0.001). CSF MMP-9 activity and endothelin-1 concentrations were correlated (r = 0.6, P = 0.02). The areas under the receiver operating characteristic curves were 0.73 (95% confidence interval [0.53 to 0.87]) and 0.91 (95% confidence interval [0.75 to 0.98]) for MMP-9 concentrations in plasma and CSF, respectively, at 24 h to predict delayed cerebral ischaemia CSF MMP-9 concentrations more than 14.3 ng ml at 24 h predicted the occurrence of delayed cerebral ischaemia with a sensitivity and specificity of 88 and 86%, respectively. After multivariate logistic analysis, only CSF MMP-9 concentrations at 24 h predicted the occurrence of delayed cerebral ischaemia (P = 0.01).

CONCLUSION

MMP-9 concentrations in both plasma and CSF, measured within 48 h after subarachnoid haemorrhage, were highly predictive of the occurrence of delayed cerebral ischaemia within the first 2 weeks.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02397759.

Cerebral Microdialysis Monitoring to Improve Individualized Neurointensive Care Therapy: An Update of Recent Clinical Data

Cerebral microdialysis (CMD) allows bedside semicontinuous monitoring of patient brain extracellular fluid. Clinical indications of CMD monitoring are focused on the management of secondary cerebral and systemic insults in acute brain injury (ABI) patients [mainly, traumatic brain injury (TBI), subarachnoid hemorrhage, and intracerebral hemorrhage (ICH)], specifically to tailor several routine interventions—such as optimization of cerebral perfusion pressure, blood transfusion, glycemic control and oxygen therapy—in the individual patient. Using CMD as clinical research tool has greatly contributed to identify and better understand important post-injury mechanisms—such as energy dysfunction, posttraumatic glycolysis, post-aneurysmal early brain injury, cortical spreading depressions, and subclinical seizures. Main CMD metabolites (namely, lactate/pyruvate ratio, and glucose) can be used to monitor the brain response to specific interventions, to assess the extent of injury, and to inform about prognosis. Recent consensus statements have provided guidelines and recommendations for CMD monitoring in neurocritical care. Here, we summarize recent clinical investigation conducted in ABI patients, specifically focusing on the role of CMD to guide individualized intensive care therapy and to improve our understanding of the complex disease mechanisms occurring in the immediate phase following ABI. Promising brain biomarkers will also be described.

Minocycline protects against delayed cerebral ischemia after subarachnoid hemorrhage via matrix metalloproteinase-9 inhibition

Objective

Delayed cerebral ischemia (DCI) is an independent risk factor for poor outcome after aneurysmal subarachnoid hemorrhage (SAH) and is multifactorial in etiology. While prior studies have suggested a role for matrix metalloproteinase-9 (MMP-9) in early brain injury after SAH, its contribution to the pathophysiology of DCI is unclear.

Methods

In the first experiment, wild-type (WT) and MMP-9^-/- mice were subjected to sham or endovascular perforation SAH surgery. In separate experiments, WT and MMP-9^-/-mice were administered vehicle or minocycline either pre- or post-SAH. All mice underwent assessment of multiple components of DCI including vasospasm, neurobehavioral function, and microvessel thrombosis. In another experiment, rabbits were subjected to sham or cisterna magna injection SAH surgery, and administered vehicle or minocycline followed by vasospasm assessment.

Results

MMP-9 expression and activity was increased after SAH. Genetic (MMP-9^-/- mice) and pharmacological (pre-SAH minocycline administration) inhibition of MMP-9 resulted in decreased vasospasm and neurobehavioral deficits. A therapeutically feasible strategy of post-SAH administration of minocycline resulted in attenuation of multiple components of DCI. Minocycline administration to MMP-9^-/- mice did not yield additional protection. Consistent with experiments in mice, both pre- and post-SAH administration of minocycline attenuated SAH-induced vasospasm in rabbits.

Interpretation

MMP-9 is a key player in the pathogenesis of DCI. The consistent attenuation of multiple components of DCI with both pre- and post-SAH administration of minocycline across different species and experimental models of SAH, combined with the excellent safety profile of minocycline in humans suggest that a clinical trial in SAH patients is warranted.

The Pathophysiology of Delayed Cerebral Ischemia

Subarachnoid hemorrhage (SAH) affects 30,000 people in the Unites States alone each year. Delayed cerebral ischemia occurs days after subarachnoid hemorrhage and represents a potentially treatable cause of morbidity for approximately one-third of those who survive the initial hemorrhage. While vasospasm has been traditionally linked to the development of cerebral ischemia several days after subarachnoid hemorrhage, emerging evidence reveals that delayed cerebral ischemia is part of a much more complicated post-subarachnoid hemorrhage syndrome. The development of delayed cerebral ischemia involves early arteriolar vasospasm with microthrombosis, perfusion mismatch and neurovascular uncoupling, spreading depolarizations, and inflammatory responses that begin at the time of the hemorrhage and evolve over time, culminating in cortical infarction. Large-vessel vasospasm is likely a late contributor to ongoing injury, and effective treatment for delayed cerebral ischemia will require improved detection of critical early pathophysiologic changes as well as therapeutic options that target multiple related pathways.

Matrix metalloproteinase 9 may be involved in contraction of vascular smooth muscle cells in an in vitro rat model of subarachnoid hemorrhage

Our previous study determined that prominent cerebral vasospasm (CVS) may occur in an in vivo model of subarachnoid hemorrhage (SAH) in rats. Matrix metalloproteinase 9 (MMP‑9) expression levels in basilar arteries were upregulated in a similar manner to the development of CVS following SAH. To identify the changes that occur in the contractility of cerebrovascular smooth muscle cells and the expression levels of MMP‑9 in an in vitro model of SAH, rat cerebrovascular smooth muscle cells were isolated, cultured, and then stimulated with hemolysate. Additionally, 2-[(4-phenoxyphenylsulfonyl)methyl]thiirane (SB-3CT), a selective MMP-9 inhibitor, was used to determine the effect of MMP‑9 on the contractility of cerebrovascular smooth muscle cells. Cerebrovascular smooth muscle cells were successfully isolated and cultured in vitro, and hemolysate stimulation enhanced their contractility and increased MMP‑9 expression levels. The present study also revealed that pretreatment with SB‑3CT decreased MMP‑9 expression levels in cerebrovascular smooth muscle cells, and reduced their contractility upon hemolysate treatment. Therefore, the current study confirmed that MMP‑9 is important for the enhancement of the contractility of cerebrovascular smooth muscle cells in an in vitro rat model of SAH.

Effects of simvastatin and taurine on delayed cerebral vasospasm following subarachnoid hemorrhage in rabbits

The aim of the current study was to observe the effects of simvastatin and taurine on delayed cerebral vasospasm (DCVS) following experimental subarachnoid hemorrhage (SAH) in rabbits. A total of 48 New Zealand white rabbits were allocated at random into four groups (control, SAH, SAH + simvastatin and SAH + taurine groups; n=12 each). The rabbit model of DCVS was established using a double hemorrhage method, which involved injecting autologous arterial blood into the cisterna magna in the SAH groups. The SAH + simvastatin group was administered oral simvastatin (5 mg/kg) daily between days 0-6. The SAH + taurine group was administered oral taurine (50 mg/kg) daily between days 0-6. Starch (50 mg/kg) was administered orally to the animals in the other two groups (control and SAH groups). The control group were not subjected to any other injections or treatment. The internal diameter and internal diameter/wall thickness of the basilar artery (BA) were measured. The expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were determined using immunohistochemical and quantitative polymerase chain reaction methods following the sacrifice of all animals on day 7. The activity of nuclear factor (NF)-κB in the BA was also measured using an electrophoretic mobility shift assay. The BA walls in the SAH + simvastatin and SAH + taurine groups exhibited reduced narrowing and corrugation of the tunica elastica interna compared with the SAH group. At the protein and cDNA levels, it was found that cerebral vasospasm of the BA in the SAH + simvastatin and SAH + taurine groups was alleviated, as indicated by the reduced expression of TNF-α, IL-1β, IL-6 and NF-κB compared with the SAH group (P<0.05). In conclusion, simvastatin and taurine reduced DCVS following SAH in rabbits, which suggests that these compounds may exert anti-inflammatory effects.

International multidisciplinary consensus conference on multimodality monitoring: cerebral metabolism

Microdialysis is a powerful technique, which enables the chemistry of the extracellular space to be measured directly. Applying this technique to patients in neurointensive care has increased our understanding of the pathophysiology of traumatic brain injury and spontaneous hemorrhage. In parallel, it is important to determine the place of microdialysis in assisting in the management of patients on an individual intention to treat basis. This is made possible by the availability of analyzers which can measure the concentration of glucose, pyruvate, lactate, and glutamate at the bedside. Samples can then be stored for later analysis of other substrate and metabolites e.g., other amino acids and cytokines. The objective of this paper is to review the fundamental literature pertinent to the clinical application of microdialysis in neurointensive care and to give recommendations on how the technique can be applied to assist in patient management and contribute to outcome. A literature search detected 1,933 publications of which 55 were used for data abstraction and analysis. The role of microdialysis was evaluated in three conditions (traumatic brain injury, subarachnoid hemorrhage, and intracerebral hemorrhage) and recommendations focused on three fundamental areas (relationship to outcome, application of microdialysis to guide therapy, and the ability of microdialysis to predict secondary deterioration).

Deficiency of tenascin-C and attenuation of blood-brain barrier disruption following experimental subarachnoid hemorrhage in mice

OBJECT Tenascin-C (TNC), a matricellular protein, is induced in the brain following subarachnoid hemorrhage (SAH). The authors investigated if TNC causes brain edema and blood-brain barrier (BBB) disruption following experimental SAH. METHODS C57BL/6 wild-type (WT) or TNC knockout (TNKO) mice were subjected to SAH by endovascular puncture. Ninety-seven mice were randomly allocated to WT sham-operated (n = 16), TNKO sham-operated (n = 16), WT SAH (n = 34), and TNKO SAH (n = 31) groups. Mice were examined by means of neuroscore and brain water content 24-48 hours post-SAH; and Evans blue dye extravasation and Western blotting of TNC, matrix metalloproteinase (MMP)-9, and zona occludens (ZO)-1 at 24 hours post-SAH. As a separate study, 16 mice were randomized to WT sham-operated, TNKO sham-operated, WT SAH, and TNKO SAH groups (n = 4 in each group), and activation of mitogen-activated protein kinases (MAPKs) was immunohistochemically evaluated at 24 hours post-SAH. Moreover, 40 TNKO mice randomly received an intracerebroventricular injection of TNC or phosphate-buffered saline, and effects of exogenous TNC on brain edema and BBB disruption following SAH were studied. RESULTS Deficiency of endogenous TNC prevented neurological impairments, brain edema formation, and BBB disruption following SAH; it was also associated with the inhibition of both MMP-9 induction and ZO-1 degradation. Endogenous TNC deficiency also inhibited post-SAH MAPK activation in brain capillary endothelial cells. Exogenous TNC treatment abolished the neuroprotective effects shown in TNKO mice with SAH. CONCLUSIONS Tenascin-C may be an important mediator in the development of brain edema and BBB disruption following SAH, mechanisms for which may involve MAPK-mediated MMP-9 induction and ZO-1 degradation. TNC could be a molecular target against which to develop new therapies for SAH-induced brain injuries.

Increased expression of angiogenic factors in cultured human brain arteriovenous malformation endothelial cells

To compare the mRNA level of angiogenic factor vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP)-2, and MMP-9 in cultured human brain arteriovenous malformation (AVM) endothelial cells (ECs) and normal brain endothelial cells (BECs). Tissue explants both from deformed vessels of AVM and normal microvessel were put into culture for endothelial cells. After the monolayer adherent ECs reached confluence, they were tested with endothelial specific marker CD34 and von Willebrand factor (vWF) by immunochemical assay. mRNA levels of VEGF-A, MMP-2, and MMP-9 in AVM endothelial cells (AVMECs) and BECs were measured by PCR. Immunostaining confirmed that more than 95 % of the cultured cells were CD34 (Fig. 1b) and/or vWF positive. Expression levels of VEGF-A and MMP-2 mRNAs were significantly higher in AVMECs than in BECs. The MMP-9 level was also increased in AVMECs, but the difference was not statistically significant. Vascular tissue explants adherent method is a better approach for isolation and culture of AVMECs. Cultured AVMECs expressed higher angiogenic factors (VEGF, MMP-2) than the controlled BECs, implicating angiogenesis plays an important role in the pathogenesis of AVM.

Characterisation of DWI-MRI confirmed cerebral infarcts in patients with subarachnoid haemorrhage and their association with MMP-9 levels

OBJECTIVES

It has been suggested that metalloproteinase-9 (MMP-9) could predict the onset of cerebral vasospasm after subarachnoidal haemorrhage (SAH). The aim of this study was to analyse, in patients with SAH, the difference between patients with MRI ischaemic infarcts and patients without, and to investigate the role of metalloproteases as a prognostic factor for ischaemic infarcts.

METHODS

Sixty eight consecutive patients with SAH and diffusion-weighted magnetic resonance imaging (DWI-MRI) done 3 weeks after SAH. We define two groups, with and without DWI-MRI infarcts. Blood samples were taken at entry, 3 days and 1 week MMP-9 was determined through ELISA method.

RESULTS

Forty per cent were male, with a mean age of 54 ± 14 years. Twenty five patients, 36.8%, had DWI-MRI infarcts; in patients with MRI infarcts, SAH was more severe (Fisher = 4 52 vs 25.6%, P = 0.037), with more morbi-mortality (Rankin>3 48 vs 18.6%, P = 0.014), and more symptomatic vasospasm (28 vs 7%, P = 0.031). Levels of MMP-9 were higher than controls, but there were no significant differences between patients with and without infarcts (first determination no infarcts 39.40 ng/ml ± 35.40 vs infarcts 49.75 ng/ml ± 34.54, P > 0.005, 3 days no infarcts 72.10 ng/ml ± 70.95 vs infarcts 62.28 ± 33.84, P > 0.005, 1 week no infarcts 148.48 ng/ml ± 142.73 vs infarcts 91.5 ng/ml ± 1.20, P > 0.005).

CONCLUSION

Thirty eight percent in a well-studied series of patients with SAH have DWI-MRI infarcts; the infarcts were associated to SAH severity, SAH outcome and symptomatic vasospasm. Metalloproteinase-9 was higher in SAH patients than in controls, but it could not discriminate the infarct patients.

Early brain injury after aneurysmal subarachnoid hemorrhage: a multimodal neuromonitoring study

Introduction

There is a substantial amount of evidence from animal models that early brain injury (EBI) may play an important role for secondary brain injury after aneurysmal subarachnoid hemorrhage (aSAH). Cerebral microdialysis (CMD) allows online measurement of brain metabolites, including the pro-inflammatory cytokine interleukin-6 (IL-6) and matrix metalloproteinase-9 (MMP-9), which is indicative for disruption of the blood-brain barrier.

Methods

Twenty-six consecutive poor-grade aSAH patients with multimodal neuromonitoring were analyzed for brain hemodynamic and metabolic changes, including CMD-IL-6 and CMD-MMP-9 levels. Statistical analysis was performed by using a generalized estimating equation with an autoregressive function.

Results

The baseline cerebral metabolic profile revealed brain metabolic distress and an excitatory response which improved over the following 5 days (P <0.001). Brain tissue hypoxia (brain tissue oxygen tension of less than 20 mm Hg) was common (more than 60% of patients) in the first 24 hours of neuromonitoring and improved thereafter (P <0.05). Baseline CMD-IL-6 and CMD-MMP-9 levels were elevated in all patients (median = 4,059 pg/mL, interquartile range (IQR) = 1,316 to 12,456 pg/mL and median = 851 pg/mL, IQR = 98 to 25,860 pg/mL) and significantly decreased over days (P <0.05). A higher pro-inflammatory response was associated with the development of delayed cerebral ischemia (P = 0.04), whereas admission disease severity and early brain tissue hypoxia were associated with higher CMD-MMP-9 levels (P <0.03). Brain metabolic distress and increased IL-6 levels were associated with poor functional outcome (modified Rankin Scale of more than 3, P ≤0.01). All models were adjusted for probe location, aneurysm securing procedure, and disease severity as appropriate.

Conclusions

Multimodal neuromonitoring techniques allow insight into pathophysiologic changes in the early phase after aSAH. The results may be used as endpoints for future interventions targeting EBI in poor-grade aSAH patients.

Correlation between the -1562C/T polymorphism in the matrix metalloproteinase-9 gene and hemorrhagic transformation of ischemic stroke

The aim of the present study was to investigate the correlation between the −1562C/T polymorphism in an intron of the matrix metalloproteinase-9 (MMP-9) gene and hemorrhagic transformation of ischemic stroke (IS). Using polymerase chain reaction-restriction fragment length polymorphism, the −1562C/T polymorphisms in 222 patients with IS were detected. The patients were divided into hemorrhagic transformation (HT; 84 cases) and non-hemorrhagic transformation (NHT) groups (138 cases) depending on the results from the susceptibility-weighted magnetic resonance imaging, which was performed between one and two weeks following stroke onset. The allele frequencies were subsequently compared. Baseline data of the two groups were comparable. The HT group exhibited a significantly lower frequency of the CT+TT genotype compared with the NHT group (17.86 vs. 30.43%, P<0.05). In addition, the frequency of T allele was significantly lower in the HT group compared with the NHT group (8.93 vs. 15.94%, P<0.05). Therefore, the results indicated that the −1562C/T polymorphism in the MMP-9 gene is correlated with hemorrhagic transformation of IS in the population studied. Furthermore, the T allele may be a protective factor for hemorrhagic transformation of IS in this population.

Consensus summary statement of the International Multidisciplinary Consensus Conference on Multimodality Monitoring in Neurocritical Care: a statement for healthcare professionals from the Neurocritical Care Society and the European Society of Intensive Care Medicine

Neurocritical care depends, in part, on careful patient monitoring but as yet there are little data on what processes are the most important to monitor, how these should be monitored, and whether monitoring these processes is cost-effective and impacts outcome. At the same time, bioinformatics is a rapidly emerging field in critical care but as yet there is little agreement or standardization on what information is important and how it should be displayed and analyzed. The Neurocritical Care Society in collaboration with the European Society of Intensive Care Medicine, the Society for Critical Care Medicine, and the Latin America Brain Injury Consortium organized an international, multidisciplinary consensus conference to begin to address these needs. International experts from neurosurgery, neurocritical care, neurology, critical care, neuroanesthesiology, nursing, pharmacy, and informatics were recruited on the basis of their research, publication record, and expertise. They undertook a systematic literature review to develop recommendations about specific topics on physiologic processes important to the care of patients with disorders that require neurocritical care. This review does not make recommendations about treatment, imaging, and intraoperative monitoring. A multidisciplinary jury, selected for their expertise in clinical investigation and development of practice guidelines, guided this process. The GRADE system was used to develop recommendations based on literature review, discussion, integrating the literature with the participants' collective experience, and critical review by an impartial jury. Emphasis was placed on the principle that recommendations should be based on both data quality and on trade-offs and translation into clinical practice. Strong consideration was given to providing pragmatic guidance and recommendations for bedside neuromonitoring, even in the absence of high quality data.

Consensus summary statement of the International Multidisciplinary Consensus Conference on Multimodality Monitoring in Neurocritical Care : a statement for healthcare professionals from the Neurocritical Care Society and the European Society of Intensive Care Medicine

Neurocritical care depends, in part, on careful patient monitoring but as yet there are little data on what processes are the most important to monitor, how these should be monitored, and whether monitoring these processes is cost-effective and impacts outcome. At the same time, bioinformatics is a rapidly emerging field in critical care but as yet there is little agreement or standardization on what information is important and how it should be displayed and analyzed. The Neurocritical Care Society in collaboration with the European Society of Intensive Care Medicine, the Society for Critical Care Medicine, and the Latin America Brain Injury Consortium organized an international, multidisciplinary consensus conference to begin to address these needs. International experts from neurosurgery, neurocritical care, neurology, critical care, neuroanesthesiology, nursing, pharmacy, and informatics were recruited on the basis of their research, publication record, and expertise. They undertook a systematic literature review to develop recommendations about specific topics on physiologic processes important to the care of patients with disorders that require neurocritical care. This review does not make recommendations about treatment, imaging, and intraoperative monitoring. A multidisciplinary jury, selected for their expertise in clinical investigation and development of practice guidelines, guided this process. The GRADE system was used to develop recommendations based on literature review, discussion, integrating the literature with the participants' collective experience, and critical review by an impartial jury. Emphasis was placed on the principle that recommendations should be based on both data quality and on trade-offs and translation into clinical practice. Strong consideration was given to providing pragmatic guidance and recommendations for bedside neuromonitoring, even in the absence of high quality data.

Controversies and evolving new mechanisms in subarachnoid hemorrhage

Despite decades of study, subarachnoid hemorrhage (SAH) continues to be a serious and significant health problem in the United States and worldwide. The mechanisms contributing to brain injury after SAH remain unclear. Traditionally, most in vivo research has heavily emphasized the basic mechanisms of SAH over the pathophysiological or morphological changes of delayed cerebral vasospasm after SAH. Unfortunately, the results of clinical trials based on this premise have mostly been disappointing, implicating some other pathophysiological factors, independent of vasospasm, as contributors to poor clinical outcomes. Delayed cerebral vasospasm is no longer the only culprit. In this review, we summarize recent data from both experimental and clinical studies of SAH and discuss the vast array of physiological dysfunctions following SAH that ultimately lead to cell death. Based on the progress in neurobiological understanding of SAH, the terms "early brain injury" and "delayed brain injury" are used according to the temporal progression of SAH-induced brain injury. Additionally, a new concept of the vasculo-neuronal-glia triad model for SAH study is highlighted and presents the challenges and opportunities of this model for future SAH applications.

Tenascin-C induces prolonged constriction of cerebral arteries in rats

Tenascin-C (TNC), a matricellular protein, is induced in association with cerebral vasospasm after subarachnoid hemorrhage. The aim of this study was to assess the vasoconstrictive effects of TNC and its mechanisms of action on cerebral arteries in vivo. Two dosages (1 and 10μg) of TNC were administered intracisternally to healthy rats, and the effects were evaluated by neurobehavioral tests and India-ink angiography at 24, 48, and 72h after the administration. Western blotting and immunohistochemistry were performed to explore the underlying mechanisms on constricted cerebral arteries after 24h. The effects of toll-like receptor 4 (TLR4) antagonists (LPS-RS), c-Jun N-terminal kinase (JNK), and p38 inhibitors (SP600125 and SB203580) on TNC-induced vasoconstriction were evaluated at 24h. Higher dosages of TNC induced more severe cerebral arterial constriction, which continued for more than 72h. TNC administration also upregulated TLR4, and activated JNK and p38 in the smooth muscle cell layer of the constricted cerebral artery. LPS-RS blocked TNC-induced TLR4 upregulation, JNK and p38 activation, and vasoconstrictive effects. SP600125 and SB203580 abolished TNC-induced TLR4 upregulation and vasoconstrictive effects. TNC may cause prolonged cerebral arterial constriction via TLR4 and activation of JNK and p38, which may upregulate TLR4. These findings suggest that TNC causes cerebral vasospasm and provides a novel therapeutic approach against it.

Regulation of enhanced cerebrovascular expression of proinflammatory mediators in experimental subarachnoid hemorrhage via the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathway

BACKGROUND

Subarachnoid hemorrhage (SAH) is associated with high morbidity and mortality. It is suggested that the associated inflammation is mediated through activation of the mitogen-activated protein kinase (MAPK) pathway which plays a crucial role in the pathogenesis of delayed cerebral ischemia after SAH. The aim of this study was first to investigate the timecourse of altered expression of proinflammatory cytokines and matrix metalloproteinase in the cerebral arteries walls following SAH. Secondly, we investigated whether administration of a specific mitogen-activated protein kinase kinase (MEK)1/2 inhibitor, U0126, given at 6 h after SAH prevents activation of the MEK/extracellular signal-regulated kinase 1/2 pathway and the upregulation of cerebrovascular inflammatory mediators and improves neurological function.

METHODS

SAH was induced in rats by injection of 250 μl of autologous blood into basal cisterns. U0126 was given intracisternally using two treatment regimens: (A) treatments at 6, 12, 24 and 36 h after SAH and experiments terminated at 48 h after SAH, or (B) treatments at 6, 12, and 24 h after SAH and terminated at 72 h after SAH. Cerebral arteries were harvested and interleukin (IL)-6, IL-1β, tumor necrosis factor α (TNF)α, matrix metalloproteinase (MMP)-9 and phosphorylated ERK1/2 (pERK1/2) levels investigated by immunohistochemistry. Early activation of pERK1/2 was measured by western blot. Functional neurological outcome after SAH was also analyzed.

RESULTS

Expression levels of IL-1β, IL-6, MMP-9 and pERK1/2 proteins were elevated over time with an early increase at around 6 h and a late peak at 48 to 72 h post-SAH in cerebral arteries. Enhanced expression of TNFα in cerebral arteries started at 24 h and increased until 96 h. In addition, SAH induced sensorimotor and spontaneous behavior deficits in the animals. Treatment with U0126 starting at 6 h after SAH prevented activation of MEK-ERK1/2 signaling. Further, U0126 significantly decreased the upregulation of inflammation proteins at 48 and 72 h following SAH and improved neurological function. We found no differences between treatment regimens A and B.

CONCLUSIONS

These results show that SAH induces early activation of the MEK-ERK1/2 pathway in cerebral artery walls, which is associated with upregulation of proinflammatory cytokines and MMP-9. Inhibition of the MEK-ERK1/2 pathway by U0126 starting at 6 h post-SAH prevented upregulation of cytokines and MMP-9 in cerebral vessels, and improved neurological outcome.

Matrix metalloproteinases in human spontaneous intracerebral hemorrhage: an update

BACKGROUND

In default of a plausible and satisfactory causal treatment for hemorrhagic stroke, a role of matrix metalloproteinases (MMPs) in the pathogenesis of cerebrovascular diseases has recently been widely discussed. The well-known impact of MMPs on extracellular matrix destruction triggered by inflammation as a foundation for several diseases, including stroke, is very much in evidence. Newly, some additional aspects of MMP function considering their intracellular activity crucial for neuronal death following ischemic brain damage have emerged. The effect of blood-brain barrier disruption caused by MMPs on the prognosis in patients suffering from spontaneous intracerebral hemorrhage (ICH) has been of interest since it throws a new light upon the pathogenesis, course and possible therapeutic approaches for this least treatable and at the same time most life-threatening form of stroke. Hence, we primarily aimed to review the current clinical knowledge on the significance of metalloproteinase activation in the course of spontaneous intracranial hemorrhage in humans. We also provide a brief characterization of the MMP enzyme family and report on the latest findings on issues arising from experimental studies.

METHODS

A Medline search using the following key words was performed: matrix metalloproteinases + spontaneous intracerebral hemorrhage/intracranial hemorrhage/bleeding/hemorrhagic stroke. We accepted studies reporting on MMP expression in adult patients with spontaneous ICH, as well as its relation to radiological and clinical features and patients' outcome. For the final review, 18 clinical studies were considered. MMP inhibition was reviewed on the basis of 11 relevant experimental studies. Also, some relevant reports on the biology of MMPs and their pathophysiology in ICH were reviewed.

RESULTS AND CONCLUSIONS

Many studies provide convincing evidence of a detrimental role of MMPs in ICH, stressing their association with neuroinflammation. The role of MMPs in hemorrhagic stroke appears critical for hematoma and brain edema growth as well as for neuronal death, which are understood as secondary brain injury and may have a considerable clinical impact. Although data on human spontaneous ICH are scarce and mostly based on small populations, they reveal the apparent correlation between MMPs and clinical and radiological ICH features as well as the functional outcome, which might rationalize future therapeutic strategies. However, attempts at MMP inhibition in spontaneous ICH have solely been made under experimental conditions and were associated with a wide range of possible side effects. Therefore, further comprehensive, elucidating investigations in this field are vital before any conclusions could be translated to humans.