Cerebrospinal Fluid Of Subarachnoid Hemorrhage Patients Research Articles

331 Validation of a Novel CSF-Based Biomarker of Mitochondrial Function

OBJECTIVES/GOALS: Determine the exosome mitochondrial DNA (mtDNA) copy number in cerebrospinal fluid (CSF) as a measure of neuronal mitochondrial integrity in patients with subarachnoid hemorrhage (SAH). Determine the patterns of beta amyloid and tau protein biology in CSF of SAH patients and correlate those measures with the clinical status of the SAH patients. METHODS/STUDY POPULATION: The CSF is collected from SAH patients undergoing ventriculostomy-based continuous CSF drainage. Adults from all ethnicities and sex are included in this study. The exosomes are isolated from CSF samples using a precipitation method and particle count and size are measured using NanoSight. The DNA is extracted using an exosomal DNA isolation kit (XCF kit). The CSF mtDNA copy number is measured using digital drop PCR with mitochondrial DNA primers. The levels of beta-amyloid (a-beta-40 and -42) and tau protein in CSF are measured using a sensitive ELISA-based assay. A quantitative evaluation of mitochondrial DNA copy number, clinical status of the SAH patients and beta amyloid, and tau protein levels will be conducted and reported. RESULTS/ANTICIPATED RESULTS: Preliminary results of four CSF samples showed similar patterns in CSF exosome particle number, particle size and exosomal mtDNA copy number in relation to samples from the admission day. Particle number decreased with time while particle size increased. More patient samples will be analyzed to confirm the patterns. We anticipate that mtDNA copy number will correlate with brain beta-amyloid and tau protein levels. Moreover, we anticipate that the clinical status of the SAH patients will associate with the mtDNA copy number. We specifically predict that higher mtDNA copy number levels will correlate with better clinical outcomes. DISCUSSION/SIGNIFICANCE: Mitochondrial function is critical to brain health, but we lack effective ways to monitor this parameter. Here we focus on a CSF based biomarker, exosome-derived mtDNA, which is intended to reflect the integrity of brain mitochondria. As bioenergetic metabolism influences beta amyloid and tau biology, predicting those levels are important.

Circadian dependency of microglial heme oxygenase-1 expression and inflammation determine neuronal injury in hemorrhagic stroke

BackgroundThe heme oxygenase-1 (HO-1) enzyme pathway is of crucial importance in the removal of toxic blood components and regulation of neuroinflammation following hemorrhagic stroke. Although a circadian pattern dependency in the incidence and severity of hemorrhagic stroke exists, it is unknown whether the activity of the HO-1 system in the context of hemorrhagic injury also exhibits circadian dependency. We hypothesized that the circadian regulation of microglial HO-1 would determine the extent of neuroinflammation and neuronal injury in a murine model of subarachnoid hemorrhage (SAH).MethodsIn vitro expression patterns of HO-1 and circadian rhythm genes were analyzed in the microglial BV-2 cell line and primary microglia (PMG) using Western blot and qPCR. PMG isolated from Hmox1fl/fl and LyzM-Cre-Hmox1fl/fl mice were used to evaluate the role of microglial HO-1. We further investigated the in vivo relevance in a murine subarachnoid hemorrhage (SAH) model using Hmox1fl/fl and LyzM-Cre-Hmox1fl/fl mice with myeloid cell HO-1 deficiency, inducing SAH at different zeitgeber (ZT) times and analyzing the expression of HO-1 and the circadian control gene Period-2 (Per-2), respectively. Furthermore, we measured the inflammatory cytokine Monocyte Chemoattractant Protein-1 (MCP-1) in the cerebrospinal fluid of SAH patients in correlation with clinical outcome.ResultsHO-1 baseline expression and response to CO with blood exposure depended on ZT. In vitro expression of circadian control genes was de-synchronized in LyzM-Cre-Hmox1fl/fl PMG and did not respond to exogenous CO exposure. We found that circadian rhythm plays a crucial role in brain damage after SAH. At ZT2, we observed less phagocytic function, more vasospasm and increased microglial activation. CO reduced mortality at ZT12 in HO-1 deficient mice and reduced the difference between ZT2 and ZT12 in the inflammatory response. Induction of MCP-1 in the CSF from SAH patients was time-dependent and correlated with the expression of circadian control genes, SAH severity, functional impairment and delirium.ConclusionsOur data point towards a crucial role for the HO-1 enzyme system and circadian control in neuronal injury after a hemorrhagic stroke.

Relationship between astrocyte damage and different levels of cerebrospinal fluid markers and prognosis in patients with subarachnoid hemorrhage.

The aim of the study was to explore the relationship between astrocyte damage and different levels of cerebrospinal fluid markers and prognosis in patients with subarachnoid hemorrhage (SAH). A total of 168 SAH patients diagnosed and treated in the emergency department of our hospital during the period October 2019 to February 2022 were randomly selected as the study subjects. The severity of these patients' condition was evaluated by Hunt-Hess grading and these subjects were graded as the low-level group (78 patients) and high-level group (90 patients) according to the evaluation results. The Extended Disability Status Scale (EDSS) score was employed to evaluate the astrocyte damage. The content of atypical chemokine receptor 3 (ACKR3), Connexin 43 (Cx43), oxygenated hemoglobin (HbO 2 ), and endothelin (ET) in cerebrospinal fluid was measured. The relationship between the content of ACKR3, Cx43, HbO 2 , and ET in cerebrospinal fluid with EDSS score was analyzed through Pearson correlation analysis. Multivariate logistic regression analysis was adopted to analyze the risk factors. ACKR3 was mainly expressed in the cytoplasm of cerebrospinal fluid monocytes, and Cx43 was mainly expressed in the cell membrane and cytoplasm. Patients in the high-level group had markedly higher expression rates of ACKR3 and Cx43 positive cells in cerebrospinal fluid than those in the low-level group ( p < 0.05). Patients in the high-level group had higher content of HbO 2 and ET in cerebrospinal fluid and EDSS score than patients in the low-level group ( p < 0.05). The content of ACKR3, Cx43, HbO 2 , and ET in cerebrospinal fluid of SAH patients was positively correlated with EDSS scores ( p < 0.05). Systolic blood pressure, Hunt-Hess grade, rebleeding, emotional control, EDSS score, ACKR3, Cx43 positive cell rate, and HbO 2 and ET expression levels were independent risk factors for the prognosis of SAH patients ( p < 0.05). Astrocyte damage in SAH patients was positively correlated with the content of ACKR3, Cx43, HbO 2 , and ET in cerebrospinal fluid. These indicators increased significantly with the increasing severity of the disease, and had certain value in reflecting the patient's condition. Astrocyte damage combined with cerebrospinal fluid markers had potential value in evaluating the severity and prognosis of patients.

Cerebrospinal fluid metabolic profiling reveals divergent modulation of pentose phosphate pathway by midazolam, propofol and dexmedetomidine in patients with subarachnoid hemorrhage: a cohort study

BackgroundAgitation is common in subarachnoid hemorrhage (SAH), and sedation with midazolam, propofol and dexmedetomidine is essential in agitation management. Previous research shows the tendency of dexmedetomidine and propofol in improving long-term outcome of SAH patients, whereas midazolam might be detrimental. Brain metabolism derangement after SAH might be interfered by sedatives. However, how sedatives work and whether the drugs interfere with patient outcome by altering cerebral metabolism is unclear, and the comprehensive view of how sedatives regulate brain metabolism remains to be elucidated.MethodsFor cerebrospinal fluid (CSF) and extracellular space of the brain exchange instantly, we performed a cohort study, applying CSF of SAH patients utilizing different sedatives or no sedation to metabolomics. Baseline CSF metabolome was corrected by selecting patients of the same SAH and agitation severity. CSF components were analyzed to identify the most affected metabolic pathways and sensitive biomarkers of each sedative. Markers might represent the outcome of the patients were also investigated.ResultsPentose phosphate pathway was the most significantly interfered (upregulated) pathway in midazolam (p = 0.0000107, impact = 0.35348) and propofol (p = 0.00000000000746, impact = 0.41604) groups. On the contrary, dexmedetomidine decreased levels of sedoheptulose 7-phosphate (p = 0.002) and NADP (p = 0.024), and NADP is the key metabolite and regulator in pentose phosphate pathway. Midazolam additionally augmented purine synthesis (p = 0.00175, impact = 0.13481) and propofol enhanced pyrimidine synthesis (p = 0.000203, impact = 0.20046), whereas dexmedetomidine weakened pyrimidine synthesis (p = 0.000000000594, impact = 0.24922). Reduced guanosine diphosphate (AUC of ROC 0.857, 95%CI 0.617–1, p = 0.00506) was the significant CSF biomarker for midazolam, and uridine diphosphate glucose (AUC of ROC 0.877, 95%CI 0.631–1, p = 0.00980) for propofol, and succinyl-CoA (AUC of ROC 0.923, 95%CI 0.785–1, p = 0.000810) plus adenosine triphosphate (AUC of ROC 0.908, 95%CI 0.6921, p = 0.00315) for dexmedetomidine. Down-regulated CSF succinyl-CoA was also associated with favorable outcome (AUC of ROC 0.708, 95% CI: 0.524–0.865, p = 0.029333).ConclusionPentose phosphate pathway was a crucial target for sedatives which alter brain metabolism. Midazolam and propofol enhanced the pentose phosphate pathway and nucleotide synthesis in poor-grade SAH patients, as presented in the CSF. The situation of dexmedetomidine was the opposite. The divergent modulation of cerebral metabolism might further explain sedative pharmacology and how sedatives affect the outcome of SAH patients.

Arginase-1 Released into CSF After Aneurysmal Subarachnoid Hemorrhage Decreases Arginine/Ornithine Ratio: a Novel Prognostic Biomarker

We hypothesized that the enzyme arginase-1 is released into the cerebrospinal fluid (CSF) during red blood cell lysis and contributes to dysregulated metabolism of the nitric oxide (NO) precursor L-arginine during aneurysmal subarachnoid hemorrhage (SAH). This prospective case–control study included 43 patients with aneurysmal SAH and ventricular drainage for clinical reasons. Longitudinal CSF samples (99) were obtained in the course of SAH. Patients were dichotomized regarding the occurrence of cerebral vasospasm syndrome (CVS) (N = 19). Arginase-1 and the amino acids L-arginine and L-ornithine were quantified in CSF. Outcome assessments included delayed cerebral ischemia (DCI) and functional status after 3 months using the modified Rankin Scale (mRS). Arginase-1 was released into the CSF of SAH patients whereas this enzyme was undetectable in controls. Compared to patients without CVS, arginase-1 levels were higher in CVS patients until day 14 after clinical event. The well-known surrogate parameter for arginase acitivity, the L-arginine to L-ornithine ratio (Arg/Orn), correlated with CSF arginase-1 levels. Arg/Orn was reduced in patients with CVS from disease onset (days 1–3, p = 0.0009) until day 14. Logistic regression analysis of early Arg/Orn was predictive for CVS (p = 0.008) and DCI (p = 0.035), independent of age, Hunt and Hess grade, and intraventricular blood. Arg/Orn < 2.71 at disease onset predicted CVS with a sensitivity of 86.7% and specificity of 72.2%. Arg/Orn ≥ 2.71 predicted excellent functional outcome. We propose a novel mechanism contributing to NO deprivation during SAH: arginase-1 is released from erythrocytes into the CSF, leading to L-arginine consumption and reduced NO bioavailability. Furthermore, Arg/Orn is a robust predictor for occurrence of CVS, DCI, and functional outcome 3 months after aneurysmal SAH. Our data provide a novel prognostic biomarker and may contribute to the development of novel therapeutic strategies in SAH. Clinical Trial Registration-URL: http://www.drks.de. Unique identifier: DRKS00015293, date of registration: 13.09.2018.

Elevation of CSF Sortilin Following Subarachnoid Hemorrhage in Patients and Experimental Model Rats

Subarachnoid hemorrhage (SAH) can cause acute neuronal injury and chronic neurocognitive deficits; biomarkers reflecting its associated neuronal injury are of potential prognostic value. Sortilin, a member of the vacuolar protein sorting 10p (Vps10p) family, is enriched in neurons and is likely involved in neurodegenerative diseases. Here, we explored sortilin in the cerebrospinal fluid (CSF) as a potential biomarker for early neuronal injury after SAH. Sortilin levels in the CSF of SAH patients (n = 11) and controls (n = 6) were analyzed by immunoblot. SAH rats surviving 3–72 h (h) were evaluated neurologically, with their brain and CSF samples examined histologically and biochemically. Sortilin protein ~100 kDa was detected in the CSF from SAH patients only, with its levels correlated to Hunt-Hess scale. Rats in the SAH groups showed poorer Garcia score and beam balancing capability than sham controls. Sortilin ~100 kDa was detectable in the CSF of the SAH, but not sham, animals. Levels of sortilin ~100 kDa and fragments ~40 kDa in cortical lysates were elevated in the SAH relative to control rats. Levels of cortical glial fibrillary acidic protein (GFAP) were also elevated in the SAH rats. In immunohistochemistry, the pattern of sortilin labeling in the brain was largely comparable between the SAH and control rats, whereas an increased astrocytic GFAP immunolabeling was evident in the former. Together, these results suggest that SAH can cause an early and remarkable rise of sortilin products in CSF, likely reflecting neuronal change. Sortilin could be further explored as a potential biomarker in some brain disorders.

Role of TREM-1 in the development of early brain injury after subarachnoid hemorrhage

Triggering receptor expressed on myeloid cells-1 (TREM-1) was found to be induced in the context of subarachnoid hemorrhage (SAH) before. This study further investigates its role in the development of SAH-induced early brain injury (EBI). Firstly, rats were randomly divided into Sham and SAH groups for analysis of temporal patterns and cellular localization of TREM-1. Secondly, TREM-1 intervention was administrated to produce Sham, vehicle, antagonist and agonist groups, for analyzing TREM-1, Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and NF-κB expressions at 24 h post-modeling, and EBI assessment at 24 h and 72 h. Thirdly, TLR4 inhibitor (TAK-242) was exploited to produce Sham, Sham+TAK-242, SAH, and SAH + TAK-242 groups to analyze the effects of TLR4 inhibition on TREM-1 induction and EBI evaluation at 72 h. Fourthly, the relationship of soluble TREM-1 (sTREM-1) levels in cerebrospinal fluid of SAH patients with Hunt-Hess grades were explored. The results showed that TREM-1 increased in the brain after experimental SAH (eSAH) early at 6 h and peaked at 48 h, which was found to be located in microglia and endothelial cells. TREM-1 inhibition attenuated EBI associated with TLR4/MyD88/NF-κB suppression, while enhancement had the opposite effects. Contrarily, TLR4 inhibition prevented TREM-1 induction and ameliorated EBI. In addition, sTREM-1 levels in SAH patients positively correlated with Hunt-Hess grades. Overall, the present study provides new evidence that TREM-1 increases dynamically in the brain after eSAH and it is located in microglia and endothelial cells, which may aggravate EBI by interacting with TLR4 pathway. And sTREM-1 in patients might act as a monitoring biomarker of EBI, providing new insights for future studies.

Cerebrospinal Fluid from Aneurysmal Subarachnoid Hemorrhage Patients Leads to Hydrocephalus in Nude Mice.

Our prior studies have found that intracerebroventricular injection of blood components can cause hydrocephalus and choroid plexus epiplexus cell activation in rats. To minimize the cross-species reaction, the current study examines whether intraventricular injection of acellular components of cerebrospinal fluid (CSF) from subarachnoid hemorrhage patients can cause hydrocephalus and epiplexus macrophage activation in nude mice which lack a T cell inflammatory response. Adult male nude mice received intraventricular injections of acellular CSF from subarachnoid hemorrhage patients or a control patient. All mice had preoperative magnetic resonance imaging as baseline and postoperative scans at 24h after CSF injection to determine ventricular volume. Brains were harvested at 24h for brain histology, immunohistochemistry, and electron microscopy. Intraventricular injection of CSF from two of five subarachnoid hemorrhage patients obtained < 48h from ictus resulted in ventricular enlargement at 24h. CSF-related hydrocephalus was associated with activation of epiplexus macrophages and ependymal injury. Components of the acellular CSF of subarachnoid hemorrhage patients can cause epiplexus macrophage activation, ependymal cell damage, and ventricular enlargement in nude mice. This may serve as a unique model to study mechanisms of hydrocephalus development following subarachnoid hemorrhage.

Defining the Mechanism of Subarachnoid Hemorrhage-Induced Pyrexia.

Fever can affect the majority of patients with subarachnoid hemorrhage (SAH) and many times no identifiable source is found for the fever whether infectious or sterile, like deep vein thrombosis. We hypothesized that fever in SAH is mediated by a NON-cyclo-oxygenase-dependent mechanism, which we neologized as subarachnoid hemorrhage-induced pyrexia (SAHiP). This hypothesis was investigated using genetically modified mice, pharmacological manipulation, cerebrospinal fluid from SAH patients, and a large cohort of SAH patients. Mice with deletions of neuronal prostaglandin EP3 receptor, global toll-like receptor 4 (TLR4), myeloid TLR4, and microglial TLR4 were subjected to SAH after being implanted with thermometers. Pathways necessary for SAHiP were identified. In SAH patients, cerebrospinal fluid was examined by flow cytometry and correlated with SAHiP. From a large cohort of SAH patients, independent associations with SAHiP were determined using logistic regression analysis. In our mouse model of SAH, microglial TLR4 is necessary for SAHiP, but independent of the neuronal prostaglandin EP3 receptor, cyclo-oxygenase, and prostaglandins. Macrophages from the cerebrospinal fluid of SAH patients with SAHiP expressed more TLR4-co-receptor than SAH patients without SAHiP. In a large cohort of SAH patients, SAHiP was found to be independently, yet inversely, associated with acetaminophen administration. SAHiP is independent of the neuronal prostaglandin EP3 receptor, cyclo-oxygenase, and prostaglandins, but dependent on microglial/macrophage TLR4 with evidence from both SAH mouse models and SAH patients.

Propentdyopents as Heme Degradation Intermediates Constrict Mouse Cerebral Arterioles and Are Present in the Cerebrospinal Fluid of Patients With Subarachnoid Hemorrhage.

Delayed ischemic neurological deficit is the most common cause of neurological impairment and unfavorable prognosis in patients with subarachnoid hemorrhage (SAH). Despite the existence of neuroimaging modalities that depict the onset of the accompanying cerebral vasospasm, preventive and therapeutic options are limited and fail to improve outcome owing to an insufficient pathomechanistic understanding of the delayed perfusion deficit. Previous studies have suggested that BOXes (bilirubin oxidation end products), originating from released heme surrounding ruptured blood vessels, are involved in arterial vasoconstriction. Recently, isolated intermediates of oxidative bilirubin degradation, known as PDPs (propentdyopents), have been considered as potential additional effectors in the development of arterial vasoconstriction. To investigate whether PDPs and BOXes are present in hemorrhagic cerebrospinal fluid and involved in the vasoconstriction of cerebral arterioles. Via liquid chromatography/mass spectrometry, we measured increased PDP and BOX concentrations in cerebrospinal fluid of SAH patients compared with control subjects. Using differential interference contrast microscopy, we analyzed the vasoactivity of PDP isomers in vitro by monitoring the arteriolar diameter in mouse acute brain slices. We found an arteriolar constriction on application of PDPs in the concentration range that occurs in the cerebrospinal fluid of patients with SAH. By imaging arteriolar diameter changes using 2-photon microscopy in vivo, we demonstrated a short-onset vasoconstriction after intrathecal injection of either PDPs or BOXes. Using magnetic resonance imaging, we observed a long-term PDP-induced delay in cerebral perfusion. For all conditions, the arteriolar narrowing was dependent on functional big conductance potassium channels and was absent in big conductance potassium channels knockout mice. For the first time, we have quantified significantly higher concentrations of PDP and BOX isomers in the cerebrospinal fluid of patients with SAH compared to controls. The vasoconstrictive effect caused by PDPs in vitro and in vivo suggests a hitherto unrecognized pathway contributing to the pathogenesis of delayed ischemic deficit in patients with SAH.

Inhibition of TREM-1 attenuates early brain injury after subarachnoid hemorrhage via downregulation of p38MAPK/MMP-9 and preservation of ZO-1

Early brain injury (EBI) mainly leads to the poor outcome of subarachnoid hemorrhage (SAH), with which inflammation is closely associated. It was reported that triggering receptor expressed on myeloid cells-1 (TREM-1), a critical inflammatory amplifier, increased in cerebrospinal fluid of SAH patients in our recent research. This study was conducted to examine the effects of TREM-1 inhibition on EBI after experimental SAH (eSAH). The endovascular perforation model of SAH was produced and 120 rats were randomly divided into four groups as sham, SAH + vehicle and SAH + LP17 (1.0 mg/kg and 3.5 mg/kg). The LP17, a selective inhibitor of TREM-1, or vehicle was administered by an intraperitoneal injection 1 h post-modeling. Western blot analysis for TREM-1, p38 mitogen-activated protein kinase (p38MAPK), matrix metalloproteinase-9 (MMP-9) and zonula occludens-1 (ZO-1) was conducted at 24 h post-modeling. EBI was assessed in terms of mortality, neuroscore, brain edema, blood–brain barrier (BBB) disruption in 24 and 72 h. The results showed that TREM-1 was induced in brain after eSAH. Both high dose (3.5 mg/kg) and low dose (1.0 mg/kg) of Lp17 significantly inhibited the induction of TREM-1, but only high dose of LP17 improved neuroscore, brain edema, and BBB disruption which are associated with downregulation of p38MAPK/MMP-9 and subsequent preservation of ZO-1. Overall, the current study provides new evidence that TREM-1 may participate in the pathogenesis of SAH-induced EBI via promoting p38MAPK/MMP-9 activation and ZO-1 degradation, while TREM-1 inhibition attenuated the EBI severity obviously, providing a novel approach for the treatment of EBI.

Abstract TP539: The Complement Protein C1q is Elevated Early in Cerebrospinal Fluid After Subarachnoid Hemorrhage but Decreased in Patients With Symptomatic Vasospasm

Introduction: Neuroinflammation is common after subarachnoid hemorrhage (SAH). The complement protein C1q is a well-known inflammatory mediator that has emerged as a key player in neuroimmune synaptic alterations. In this study, we sought to evaluate changes in cerebrospinal fluid (CSF) C1q after SAH and its association with outcome and symptomatic vasospasm (sVS). Methods: Subjects with SAH were recruited from a regional referral center. Cases were eligible to participate if they had nontraumatic aneurysmal SAH and an external ventricular drain. Samples were obtained within 72 hours of symptom onset. Control subjects were those undergoing lumbar puncture with normal CSF and normal brain MRI. C1q levels were determined using commercially available ELISA, normalized by total CSF protein, and divided into tertiles. SAH subjects were prospectively followed through hospitalization and categorized into those with good outcome (Glasgow Outcome Scale, GOS, of 5) or poor outcome (GOS of 2-4). Patients were also further categorized into those with and without sVS, defined by the presence of arterial narrowing on angiography and neurological deterioration. The rates of patients with poor outcome and sVS in each C1q tertile were compared. Results: We analyzed the CSF of 29 SAH and 11 control patients. Mean age of SAH patients was higher than controls (53.2 vs. 42.0, p=0.03) while there were no sex differences across groups. Levels of C1q were elevated in SAH patients compared to controls (p=0.02). Within the SAH group, 7 (24%) were defined as good outcome while 22 (76%) were defined as poor outcome. Mean C1q levels were comparable between these two groups (p=0.61). Symptomatic vasospasm occurred in 18 (62%) SAH patients - 16 (89%) with poor outcome and 2 (11%) with good outcome. Patients with sVS had decreased levels of C1q compared to those without (p=0.03). The rate of poor outcome per tertile of C1q was 100%, 60%, and 70%, while the rate of sVS per tertile was 88%, 70%, and 40% of patients. Conclusions: The complement protein C1q is elevated in CSF of SAH patients and may contribute to early neuroinflammation. C1q levels also appear to be lower in patients who experience sVS, suggesting that elevated C1q may have a protective role in early SAH.

Inflammasome Proteins in Cerebrospinal Fluid of Patients with Subarachnoid Hemorrhage are Biomarkers of Early Brain Injury and Functional Outcome

Aneurysmal subarachnoid hemorrhage (SAH) remains a devastating disease with significant morbidity and mortality. To date, clinical variables are still used to evaluate injury severity and prognosis. This study was designed to investigate the role of cerebrospinal fluid (CSF) inflammasome proteins as laboratory-based biomarkers of brain injury severity and outcome in SAH patients. Ten control patients and 24 SAH patients were prospectively enrolled in this study. CSF samples were collected within 72 hours after SAH. Levels of inflammasome proteins in the CSF, including NLRP1, ASC, and caspase-1 were analyzed. Immunoblot analysis exhibited that levels of NLRP1, ASC and caspase-1 were elevated in the CSF of SAH patients (P < 0.0001, P= 0.0178, and P < 0.0001, respectively). In the group of SAH patients, these inflammasome proteins were significantly higher in the patients with cerebral edema on computed tomographic scans (P= 0.0002, P= 0.0005, and P= 0.0004, respectively), and in the patients with acute hydrocephalus (P= 0.0009, P= 0.00017, and P= 0.0016, respectively). Higher levels of inflammasome proteins were associated with severe SAH and poor outcome 3 months after the SAH. High level of NLRP1 was the independent risk factor of poor outcome after SAH (P= 0.049, odds ratio= 1.730). Inflammasome proteins are potential biomarkers to assess early brain injury and to predict functional outcome after SAH.

Elevated IL-6 and TNF-α Levels in Cerebrospinal Fluid of Subarachnoid Hemorrhage Patients.

The present study investigated the correlation between interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) levels in cerebrospinal fluid (CSF) and subarachnoid hemorrhage (SAH) progression. A meta-analysis was further conducted from pooled data to analyze the clinical value of IL-6 and TNF-α in SAH diagnosis. In our case-control study, a total of 57 SAH patients were assigned to two groups, CVS group (n = 27) and non-CVS group (n = 30), based on the presence of cerebral vasospasm (CVS). In addition, 65 healthy subjects were enrolled as controls. IL-6 and TNF-α levels in CSF were measured in all the study subjects by enzyme-linked immunosorbent assay (ELISA). For meta-analysis, an exhaustive literature search was conducted to identify relevant published articles and strict inclusion and exclusion criteria were applied to select studies for the present meta-analysis. Data extracted from these studies was analyzed using STATA 12.0 software. IL-6 and TNF-α levels in CSF of SAH patients were markedly higher than those of healthy controls (all P < 0.001). Further, CVS patients showed elevated IL-6 and TNF-α levels in CSF compared to non-CVS patients (all P < 0.001). The increase in IL-6 and TNF-α levels in CSF correlated with the increasing disease severity, based on Hunt-Hess grade, in SAH patients (all P < 0.05). Our meta-analysis also confirmed that IL-6 and TNF-α CSF levels were markedly higher in SAH patients compared to healthy controls (all P < 0.001). Ethnicity-stratified analysis showed that both IL-6 and TNF-α CSF levels were elevated in Asian SAH patients, compared to their healthy counterparts (all P < 0.05). The TNF-α CSF levels were significantly higher in Caucasian SAH patients (P < 0.001), but the IL-6 CSF levels showed no such differences compared to the healthy controls (P = 0.219). Subgroup analysis based on the presence of CVS showed that both IL-6 and TNF-α CSF levels were markedly higher in CVS patients than those in non-CVS patients (all P < 0.05). Our results provide strong evidence that IL-6 and TNF-α CSF levels are elevated in SAH patients and may participate in SAH development. Thus, these two cytokines could be important biomarkers for early diagnosis and disease monitoring in SAH patients.

HMGB1 Level in Cerebrospinal Fluid as a Marker of Treatment Outcome in Patients with Acute Hydrocephalus Following Aneurysmal Subarachnoid Hemorrhage

Attempts to clarify mechanisms of early brain injury in subarachnoid hemorrhage (SAH) revealed a high-mobility group box 1 (HMGB1) protein involvement in sterile inflammation initiated by aneurysm rupture. This study aims at assessing the prognostic value of HMGB1 in comparison with traditional biomarkers. Ten patients with Fisher grade 4 SAH and acute hydrocephalus underwent endovascular coiling and ventriculostomy. HMGB1 level was measured in cerebrospinal fluid (CSF) samples collected on first, fifth, and 10th day. HMGB1 level in first sample was correlated with treatment outcome assessed in Glasgow outcome scale (GOS) at 3 months. Obtained results were compared with plasma inflammatory markers, clinical grading scales, and imaging grading scales. HMGB1 level in consecutive samples was analyzed in search of concentration trends correlating with patients' outcome. HMGB1 level in CSF of SAH patients, in contrast to control group, is significantly elevated (P < .001). Good (GOS > 3) and poor (GOS ≤ 3) outcome patients differ significantly in HMGB1 level on admission (P < .01). The strongest correlation to patients' outcome was found for Hunt and Hess scale (R = -.887, P < .01), HMGB1 level (R = -.859, P < .01), and World Federation of Neurological Surgeons scale (R = -.832, P < .01). Constant and high HMGB1 level of 10 ng/mL or more in consecutive CSF samples identifies nonsurvivors. HMGB1 protein is elevated in SAH patients. Changes in the concentration of HMGB1 in consecutive samples of the CSF correlate with outcome. Our results encourage further proteomic investigation.

Abstract T P351: Unbound Iron and Ceruloplasmin Levels in Cerebrospinal Fluid Are Associated with Development of Deep Cerebral Infarcts Following Subarachnoid Hemorrhage

Introduction: Iron-dependent formation of reactive oxygen species has been implicated in the development of vasospasm (VSP) and neuronal injury following experimental subarachnoid hemorrhage (SAH). We report the association between unbound (“free”) iron in CSF of SAH patients and the risk of angiographic vasospasm and cerebral infarcts (CI) on neuroimaging from a recently completed pilot study. Methods: Samples of cerebrospinal fluid (CSF) were obtained on days 1, 3, and 5. A fluorometric assay that relies on an oxidation sensitive probe was used to measure redox active iron (REDOX-Fe). Ceruloplasmin (Cp) concentration and levels of malondialdehyde (MDA), a marker of lipid peroxidation were also measured. We prospectively collected and recorded demographic, clinical, and radiological data. Logistic regression and Wilcoxon Rank Sum test were used. Results: Five of 12 patients developed angiographic VSP (41.6%) and eight developed CI (66.6%). Mean REDOX-Fe was higher in patients with CI (3.96 ± 0.97 Vs. 2.77 ± 0.87 mcg/dl, p 0.07), particularly in patients with deep-seated strokes (4.56 ± 0.67 Vs. 3.35 ± 0.89, p 0.03). Levels of Cp at day 3 were lower in patients with deep strokes (34,092 ± 23,780 Vs. 86,045 ± 34,752 ng/ml, p 0.03). A trend towards higher REDOX-Fe on day 3 in patients who developed VSP (4.52 ± 1.16 Vs. 2.96 ± 0.71, p 0.07), and lower Cp levels on day 5 (45,033 ± 29,079 Vs. 63,044 ± 24,821, p 0.1) was found. Levels of MDA were higher in patients who developed CI (10.36 ± 4.36 Vs. 5.9 ± 4.2 nmol, p 0.08). Conclusions: In this preliminary study we found higher concentrations of redox active iron in CSF of SAH patients who develop deep-seated CI on neuroimaging. Evidence of increased oxidative damage correlated with development of CI. A possible association between non-protein bound iron and angiographic VSP is suggested as well. Ceruloplasmin may exert a protective effect in this setting. Further studies are needed to validate these findings.

Abstract T P359: Regulation of Cerebral Ceramide Levels after Subarachnoid Hemorrhage

Background: Ceramide (Cer) participates in neuronal and oligodendroglial cell death and neuroinflammation. We have previously shown that Cer levels increase in the cerebrospinal fluid (CSF)of patients with subarachnoid hemorrhage (SAH). The goal of this study is to further characterize the origin of Cer after SAH. Methods: Cer and dihydroceramide (DHC) levels as well as the activity of Acid (ASMase) and Neutral sphingomyelinase (NSMase) were measured in the CSF of SAH patients and controls. The de novo synthesis of Cer was estimated by correlating Cer with DHC levels using Spearman correlation. The activity of intracellular enzymes that regulate Cer homeostasis including ASMase, NSMase, sphingomyelinase synthase (SMS) and glucosylceramide synthase (GCS) was investigated using the rat model of SAH. Brain homogenates were used for in vitro enzyme activity measurement. The results were compared using non-parametric analysis. Results: A total of 26 SAH patients and 8 controls were included in the study. Compared to controls, SAH patients had higher Cer (12.4±8.8 vs. 53.8±48pmol/ml; p=0.001) and DHC (1.4±1.1 vs. 4.7±3.4pmol/ml; p=0.001) in the CSF. In the SAH group, Cer correlated well with DHC (rho=0.91; p&lt;0.001) suggesting a substantial contribution of the de novo pathway to Cer production. ASMase activity in the CSF of human subjects was higher in SAH than in controls (15.04±4.75 vs.9.62±3.88 IF/μl.min; p=0.017) indicating an increased turnover of sphingomyeline into Cer. Additionally, compared to the controls (n=4), brain samples from SAH animals (n=5) had higher ASMase (15.7±2.1 vs. 9.55±1.53 IF/μg.min; p=0.025) and GCS (1.38±0.35% vs. 0.70±0.04%; p=0.025) enzyme activity. On the other hand, NSMase (1.78±0.55 vs. 1.02±0.75 IF/μg.min; p&gt;0.05) and SMS (7.1±0.9% vs. 9.1±3.8%; p&gt;0.05) activities were similar in both groups. Conclusions: The increase of Cer after SAH may be explained by the elevation in both ASMase activity and the de novo Cer biosynthetic pathway. GCS transforms Cer into less toxic glycosphingolipids, suggesting that this enzyme may constitute an endogenous Cer detoxifying mechanism.

Increase ICAM-1 and LFA-1 expression by cerebrospinal fluid of subarachnoid hemorrhage patients: Involvement of TNF-α

Subarachnoid hemorrhage (SAH) is a frequent occurrence in cerebrovascular accidents, and inflammation occurs in the subarachnoid space after SAH. Arachnoid cells have the capability to present antigens and active T-lymphocytes after stimulation by cerebrospinal fluid (CSF). However, the effect of CSF on T-lymphocytes and arachnoid cell adhesion was not clearly understood. In this study, we used ELISA to detected tumor necrosis factor-α (TNF-α) content in CSF of SAH patients. CSF or recombinant TNF-α were applied on arachnoid cells and T-lymphoctes, and RT-PCR and western blotting were performed to determine the expression of intercellular adhesion molecule-1 (ICAM-1) in arachnoid cells and Lymphocyte Function-Associated Antigen-1 (LFA-1) in T-lymphocytes, respectively. Meanwhile, the Matrix Metal Proteinase-9 (MMP-9) expression in these cells was also determined. We found that the content of TNF-α in the CSF was significantly increased in the CSF of SAH patients (from 22±8pg/mL of healthy people to 436–450pg/mL of SAH patients). Treatement with CSF could increase the expression of ICAM-1in arachnoid cells and that of LFA-1 in T-lymphocytes, mainly through the increased levels of TNF-α. We also found that the co-culture of arachnoid cells and T-lymphocytes increased the expression of MMP-9 in both cells through the interaction of ICAM-1 of and LFA-1. All of these results suggested that arachnoid cells are involved in the T-lymphocytes invasion in the subarachnoid space after SAH.

Abstract 2283: Relative Deficiency of Vascular Endothelial Growth Factor (VEGF) in Subarachnoid Hemorrhage.

Cerebral vasospasm (VS) after subarachnoid hemorrhage (SAH) is associated with delayed cerebral ischemia and poor neurological outcome. We have recently reported that shortly after SAH, there is a dramatic elevation in the levels of the endogenous VEGF-antagonist soluble fms- like tyrosine kinase-1 (sFlt1), particularly among individuals that will later develop symptomatic VS (sVS). Based on this observation we have proposed that an imbalance in the levels of endogenous angiogenic and anti-angiogenic factors occurs in SAH. In this study we examined the association of cerebrospinal fluid (CSF) levels of VEGF, sFlt1, and VEGF/sFlt1 ratio with vasospasm in SAH patients. We studied seventeen patients with Fisher Grade 3 aneurysmal SAH and five controls with no prior history of neurological disorders who underwent lumbar puncture for headache and had normal CSF studies. Demographics and medical history were documented. Patients were followed prospectively and samples of CSF were obtained within 48-hours of symptoms onset. VEGF and sFlt1 levels were determined using commercially available ELISA tests (R&amp;D Systems). SAH subjects were subcategorized into those with sVS and those who did not develop symptomatic VS (noVS). sVS was defined as the occurrence of neurological deterioration in the setting of angiographically proven VS and in the absence of other conditions that could explain the neurological decline. Ratios and levels of the compounds of interest in the different groups were compared using the nonparametric Mann-Whitney U test. Age, history of hypertension, exposure to elicit drugs, RBC count in the CSF and proteinorrachia were not statistically different between sVS and noVS groups. Similar to what has been described by others, compared to controls, SAH patients showed a trend towards having higher VEGF levels in the CSF (106±53 vs. 180±172 pg/mL); this, however, did not reach statistical significance (p&gt;0.05). The CSF levels of sFlt1 were 46±23 pg/mL in the control group and 598±423 pg/mL in the SAH group (p=0.01). Among patients with SAH, sFlt1 levels were 1018±797 pg/mL in the sVS group and 304±184 pg/mL in the noVS group (p=0.01). The mean VEGF/sFlt1 ratios were 2.27±0.25 in controls, 0.39±0.25 in SAH patients, 0.23±0.10 in the sVs group, and 0.61±26 in the noVS group (p=0.02). An early elevation in sFlt1 levels and a relative deficiency of VEGF occur in the CSF of SAH patients, particularly in those with sVS. These results suggest that an imbalance in the production of angiogenic and anti-angiogenic factors may be part of the pathogenesis of VS and that analysis of these molecules might potentially have a role in predicting sVS in SAH patients.

High-Mobility Group Box 1 Protein in CSF of Patients with Subarachnoid Hemorrhage

High-mobility group box 1 protein (HMGB1) is a nuclear factor that is a potent proinflammatory mediator, and may trigger increases in other inflammatory cytokines. The inflammatory cytokines in the cerebrospinal fluid (CSF) of patients with subarachnoid hemorrhage (SAH) have been reported previously, but HMGB1 has not. In this study, we measured HMGB1 and the inflammatory cytokines in the CSF of patients with SAH. CSF samples were collected on days 3, 7, and 14 from the drainage tubes of the postaneurysm clips of 39 patients with SAH. HMGB1, interleukin-6 (IL-6), IL-8, and tumor necrosis factor alpha (TNF-alpha) were measured in the CSF, and compared between the patients with favorable (good recovery and moderate disability) and unfavorable outcomes (severe disability, vegetative state, and death) at 3 months. In the unfavorable outcome group, HMGB1 (P = 0.017), IL-6 (P = 0.003), IL-8 (P = 0.041), and TNF-alpha (P = 0.002) were significantly increased. HMGB1 correlated significantly with IL-6, IL-8, and TNF-alpha (R = 0.672, 0.421, and 0.697, respectively). HMGB1 was increased in the CSF of SAH patients with an unfavorable outcome, as were the other cytokines. These results suggest that HMGB1 and cytokines are related to the brain damage observed after SAH. HMGB1 might play a key role in the inflammatory response in the CNS of SAH patients.