Serum and cerebrospinal fluid concentrations of E-selectin in patients with aneurysmal subarachnoid hemorrhage

Advances in biomarkers for vasospasm - Towards a future blood-based diagnostic test

Objective

Cerebral vasospasm and the resultant delayed cerebral infarction is a significant source of mortality following aneurysmal SAH. Vasospasm is currently detected using invasive or expensive imaging at regular intervals in patients following SAH, thus posing a risk of complications following the procedure and financial burden on these patients. Currently, there is no blood-based test to detect vasospasm.

Methods

PubMed, Web of Science, and Embase databases were systematically searched to retrieve studies related to cerebral vasospasm, aneurysm rupture, and biomarkers. The study search dated from 1997 to 2022. Data from eligible studies was extracted and then summarized.

Results

Out of the 632 citations screened, only 217 abstracts were selected for further review. Out of those, only 59 full text articles met eligibility and another 13 were excluded.

Conclusions

We summarize the current literature on the mechanism of cerebral vasospasm and delayed cerebral ischemia, specifically studies relating to inflammation, and provide a rationale and commentary on a hypothetical future bloodbased test to detect vasospasm. Efforts should be focused on clinical-translational approaches to create such a test to improve treatment timing and prediction of vasospasm to reduce the incidence of delayed cerebral infarction.

Profiling of Circulating Gene Expression Reveals Molecular Signatures Associated with Intracranial Aneurysm Rupture Risk

BACKGROUND

Following detection, rupture risk assessment for intracranial aneurysms (IAs) is critical. Towards molecular prognostics, we hypothesized that circulating blood RNA expression profiles are associated with IA risk.

METHODS

We performed RNA sequencing on 68 blood samples from IA patients. Here, patients were categorized as either high or low risk by assessment of aneurysm size (≥ 5 mm = high risk) and Population, Hypertension, Age, Size, Earlier subarachnoid hemorrhage, Site (PHASES) score (≥ 1 = high risk). Modified F-statistics and Benjamini-Hochberg false discovery rate correction was performed on transcripts per million-normalized gene counts. Protein-coding genes expressed in ≥ 50% of samples with a q value < 0.05 and an absolute fold-change ≥ 2 were considered significantly differentially expressed. Bioinformatics in Ingenuity Pathway Analysis was performed to understand the biology of risk-associated expression profiles. Association was assessed between gene expression and risk via Pearson correlation analysis. Linear discriminant analysis models using significant genes were created and validated for classification of high-risk cases.

RESULTS

We analyzed transcriptomes of 68 IA patients. In these cases, 31 IAs were large (≥ 5 mm), while 26 IAs had a high PHASES score. Based on size, 36 genes associated with high-risk IAs, and two were correlated with the size measurement. Alternatively, based on PHASES score, 76 genes associated with high-risk cases, and nine of them showed significant correlation to the score. Similar ontological terms were associated with both gene profiles, which reflected inflammatory signaling and vascular remodeling. Prediction models based on size and PHASES stratification were able to correctly predict IA risk status, with > 80% testing accuracy for both.

CONCLUSIONS

Here, we identified genes associated with IA risk, as quantified by common clinical metrics. Preliminary classification models demonstrated feasibility of assessing IA risk using whole blood expression.

Hematological biomarkers for predicting carotid artery vasospasm during carotid stenting

Introduction

The vasospasm of carotid arteries is important for the progression of neurological sequelae. Many mechanisms have been found to be related to this clinical phenomenon. Predicting this event by using hematological biomarkers may provide opportunities for adopting preventive measures against unfavorable neurovascular complications. The aim of this study is to determine the hematological predictors of carotid artery vasospasm during carotid stenting.

Material and methods

A total of 120 patients who underwent carotid stenting were divided into two groups: those with and without carotid artery vasospasm. Carotid artery vasospasm was angiographically defined as transient or persistent emergent stenosis or irregularity of the vessel wall without evidence of thrombosis during carotid stenting. The hematological parameters were compared between 21 patients who developed carotid artery vasospasm (17.5%) and 99 patients who did not (82.5%).

Results

The mean age of the patients with carotid artery vasospasm and without carotid artery vasospasm was 66 ±8 and 70 ±8 years, respectively. Creatinine levels within 0.5–0.9 (OR = 3.704, 95% CI: 1.245–11.019, p = 0.019), each 1000 unit increase in neutrophil count (OR = 1.567, 95% CI: 1.027–2.392, p = 0.037) and presence of diabetes (OR = 3.081, 95% CI: 1.116–8.505, p = 0.030) were the independent predictors of carotid artery vasospasm in carotid arteries during carotid stenting.

Conclusions

The prediction of carotid artery vasospasm during carotid stenting should help clinicians adopt preventive measures against the development of neurological sequelae. This study found that creatinine levels, increased neutrophil count and presence of diabetes are independent predictors of carotid artery vasospasm.

Mechanisms of neuroinflammation and inflammatory mediators involved in brain injury following subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular disorder. Neuroinflammation is a critical cause of brain injury following SAH in both acute and chronic phases. While accumulating evidence has shown that therapies targeting neuroinflammation exerted beneficial effects in experimental SAH, there is little clinical evidence. One of the factors making neuroinflammation complicated is that inflammatory signaling pathways and mediators act as protective or detrimental responses at different phases. In addition, biomarkers to detect neuroinflammation are little known in clinical settings. In this review, first, we discuss how the inflammatory signaling pathways contribute to brain injury and other secondary pathophysiological changes in SAH. Damage-associated molecular patterns arising from mechanical stress, transient global cerebral ischemia, red blood cell breakdown and delayed cerebral ischemia following SAH trigger to activate pattern recognition receptors (PRRs) such as Toll-like receptors, nucleotide-binding oligomerization domain-like receptors, and receptors for advanced glycation end products. Most of PRRs activate common downstream signaling transcriptional factor nuclear factor-κΒ and mitogen-activated protein kinases, releasing pro-inflammatory mediators and cytokines. Next, we focus on how pro-inflammatory substances play a role during the course of SAH. Finally, we highlight an important inducer of neuroinflammation, matricellular protein (MCP). MCPs are a component of extracellular matrix and exert beneficial and harmful effects through binding to receptors, other matrix proteins, growth factors, and cytokines. Treatment targeting MCPs is being proved efficacious in pre-clinical models for preventing brain injury including neuroinflammation in SAH. In addition, MCPs may be a candidate of biomarkers predicting brain injury following SAH in clinical settings.

Hepatitis B virus infected patients show increased risk of cerebral aneurysm rupture: A retrospective analysis

BACKGROUND

The mechanism responsible for cerebral aneurysm (CA) formation and rupture remains unclear. Some studies showed vascular involvement could be observed in systemic vasculitis caused by Hepatitis B. Therefore, it is necessary to determine the possibility by which hepatitis B virus (HBV) infection might be associated with CA.

METHODS AND RESULTS

We retrospectively studied patient details and serological markers of HBV infection among 229 patients presenting with CA on admission to the Neurosurgery Department at Beijing Tiantan Hospital between March 2016 and February 2017. Clinical data, radiologic findings and clinical features of HBV infection were analyzed by SPSS. The results showed a significant association between HBsAg positive (p = 0.014), anti-HBc positive (p = 0.045) and CA rupture. Univariate analysis revealed patients that were HBsAg positive (OR: 4.828; 95% CI: 1.363-17.099; p = 0.015) and anti-HBc positive (OR: 1.804; 95% CI: 1.010-3.223; p = 0.046) were associated with CA rupture. Compared with other confounding risk factors for rupture in the statistical analysis, HBsAg positive status (OR: 4.085; 95% CI: 1.011-16.513; p = 0.048) remained positively associated with CA rupture.

CONCLUSIONS

Observation showed that HBsAg positivity was associated with CA rupture.

Plasma and CSF miRNA dysregulations in subarachnoid hemorrhage reveal clinical courses and underlying pathways

BACKGROUND

Subarachnoid hemorrhage (SAH) is fatal and detrimental to quality of life. Clinically, options for monitoring are often limited, potentially missing subtle neurological changes especially in low-grade patients. This article reviewed miRNA dysregulation in SAH and analyzed their functional and clinical relevance.

METHODS

With adherence to PRISMA guideline, PubMed, EMBASE, GEO and ArrayExpress were searched comprehensively for relevant clinical and animal models. Datasets were analyzed and enriched by experimentally validated targets and multiple databases using R v3.4.2, Ingenuity Pathway Analysis, and miRPath v3.0.

RESULTS

Among 1926 search results, 18 studies were screened for full-text assessment. The 8 included studies revealed a marked miRNA dysregulation after SAH. 2 datasets were retrieved. In both serum and CSF, different miRNA profiles were associated with Early Brain Injury, Delayed Cerebral Infarction, vasospasm and prognosis. In CSF, a dramatic restructure of inter-miRNA correlation matrix was observed. Enrichment analysis revealed strong association (1) BBB instability, with adherens, extra-cellular matrix, actin cytoskeleton, integrin, TGF-β, Wnt/β-catenin etc; (2) autophagy, with MTORC1, HIF-1, ULK2, and FoxO etc; (3) apoptosis, with PI3K-Akt, p53, and AMPK. We analyzed common miRNAs across SAH and cerebral ischemia. They were related to neuronal differentiation, oxidation stress, apoptosis, angiogenesis, Alzheimer's disease, NMDA-induced calcium influx, excitotoxicity and NO production.

CONCLUSIONS

Clinical progression of SAH is associated with different miRNA fingerprints. They carry neuro-pathological relevance and can be a potential biomarker which compliments SAH management.

Vascular diseases and bleedings

Diseases of the central nervous system that are caused by an underlying vascular pathology typically result in either hemorrhage or ischemia. Most prominent entities include spontaneous subarachnoid hemorrhage, spontaneous intracerebral hemorrhage, and ischemic stroke. For anatomic reasons, cerebrospinal fluid (CSF) qualifies as body fluid for the exploration of biomarkers in these disorders. Even though in subarachnoid hemorrhage a few CSF parameters have been established for routine diagnostic purposes, there is still an unmet need and broad interest in the identification of molecules that would allow further insight into disease mechanisms and supplement patients' medical care. This chapter provides an overview on what is presently known about CSF biomarkers in spontaneous subarachnoid hemorrhage, spontaneous intracerebral hemorrhage, and ischemic stroke. We recapitulate current evidence on established diagnostic tests, discuss the role of various CSF molecules in the pathophysiology of these diseases, and illuminate their potential use in future clinical practice. Furthermore, we address methodologic aspects as well as shortcomings of research in this field.

Time Courses of Inflammatory Markers after Aneurysmal Subarachnoid Hemorrhage and Their Possible Relevance for Future Studies

Object

Aneurysmal subarachnoid hemorrhage triggers an intense inflammatory response, which is suspected to increase the risk for secondary complications such as delayed cerebral ischemia (DCI). However, to date, the monitoring of the inflammatory response to detect secondary complications such as DCI has not become part of the clinical routine diagnostic. Here, we aim to illustrate the time courses of inflammatory parameters after aneurysmal subarachnoid hemorrhage (aSAH) and discuss the problems of inflammatory parameters as biomarkers but also their possible relevance for deeper understanding of the pathophysiology after aSAH and sophisticated planning of future studies.

Materials and methods

In this prospective cohort study, 109 patients with aSAH were initially included, n = 28 patients had to be excluded. Serum and—if possible—cerebral spinal fluid samples (n = 48) were retrieved at days 1, 4, 7, 10, and 14 after aSAH. Samples were analyzed for leukocyte count and C-reactive protein (CRP) (serum samples only) as well as matrix metallopeptidase 9 (MMP9), intercellular adhesion molecule 1 (ICAM1), and leukemia inhibitory factor (LIF) [both serum and cerebrospinal fluid (CSF) samples]. Time courses of the inflammatory parameters were displayed and related to the occurrence of DCI.

Results

We illustrate the time courses of leukocyte count, CRP, MMP9, ICAM1, and LIF in patients’ serum samples from the first until the 14th day after aSAH. Time courses of MMP9, ICAM1, and LIF in CSF samples are demonstrated. Furthermore, no significant difference was shown relating the time courses to the occurrence of DCI.

Conclusion

We estimate that the wide range of the measured values hampers their interpretation and usage as a biomarker. However, understanding the inflammatory response after aSAH and generating a multicenter database may facilitate further studies: realistic sample size calculations on the basis of a multicenter database will increase the quality and clinical relevance of the acquired results.

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.

E-Selectin Expression Increased in Human Ruptured Cerebral Aneurysm Tissues

Objectives:

The purpose of the present study is to investigate the expression of inflammation factor endothelial-leukocyte adhesion molecule (E-selectin, CD62E) in cerebral aneurysm walls and its relationship with aneurysm rupture.

Methods:

Cerebral aneurysm tissue samples were collected at the time of surgical clipping of nine patients with history of subarachnoid hemorrhage, and then compared with control artery tissues from the superficial temporal arteries (STA) of five patients with intracranial tumors. Immunohistochemistry (IHC) was performed to reveal and localize E-selectin expression in the aneurysms and artery tissues. Western blot analysis was used to relatively quantify the level of E-selectine protein expression in cerebral aneurysms when compared with normal arteries.

Results:

E-selectin was detected in the wall of all the aneurysm tissue samples and was rarely found in normal control arteries by IHC, and it was concentrated in proliferating and disorganized epithelia cells. Moreover, with the Western blot method, the E-selectin protein level increased significantly in aneurysm tissues compared to normal STA.

Conclusions:

E-selectin might be an important factor involved in the process of cerebral aneurysm formation and rupture, by promoting inflammation and weakening cerebral artery walls.

Inflammation, vasospasm, and brain injury after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) can lead to devastating neurological outcomes, and there are few pharmacologic treatments available for treating this condition. Both animal and human studies provide evidence of inflammation being a driving force behind the pathology of SAH, leading to both direct brain injury and vasospasm, which in turn leads to ischemic brain injury. Several inflammatory mediators that are elevated after SAH have been studied in detail. While there is promising data indicating that blocking these factors might benefit patients after SAH, there has been little success in clinical trials. One of the key factors that complicates clinical trials of SAH is the variability of the initial injury and subsequent inflammatory response. It is likely that both genetic and environmental factors contribute to the variability of patients' post-SAH inflammatory response and that this confounds trials of anti-inflammatory therapies. Additionally, systemic inflammation from other conditions that affect patients with SAH could contribute to brain injury and vasospasm after SAH. Continuing work on biomarkers of inflammation after SAH may lead to development of patient-specific anti-inflammatory therapies to improve outcome after SAH.

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.

The importance of early brain injury after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a medical emergency that accounts for 5% of all stroke cases. Individuals affected are typically in the prime of their lives (mean age 50 years). Approximately 12% of patients die before receiving medical attention, 33% within 48 h and 50% within 30 days of aSAH. Of the survivors 50% suffer from permanent disability with an estimated lifetime cost more than double that of an ischemic stroke. Traditionally, spasm that develops in large cerebral arteries 3-7 days after aneurysm rupture is considered the most important determinant of brain injury and outcome after aSAH. However, recent studies show that prevention of delayed vasospasm does not improve outcome in aSAH patients. This finding has finally brought in focus the influence of early brain injury on outcome of aSAH. A substantial amount of evidence indicates that brain injury begins at the aneurysm rupture, evolves with time and plays an important role in patients' outcome. In this manuscript we review early brain injury after aSAH. Due to the early nature, most of the information on this injury comes from animals and few only from autopsy of patients who died within days after aSAH. Consequently, we began with a review of animal models of early brain injury, next we review the mechanisms of brain injury according to the sequence of their temporal appearance and finally we discuss the failure of clinical translation of therapies successful in animal models of aSAH.

Proteomic biomarker discovery in cerebrospinal fluid for cerebral vasospasm following subarachnoid hemorrhage

Currently, there are no established biomarkers for diagnosing preclinical vasospasm or monitoring its progression. Two areas of extensive biomarker research are neuroimaging and biochemical markers in body fluids, such as cerebrospinal fluid (CSF). We performed a review of studies conducted over the past 2 decades summarizing the science to date and the evolution of CSF biomarkers in subarachnoid hemorrhage (SAH). A Medline search performed using the search terms "subarachnoid hemorrhage marker AND cerebrospinal fluid," limited to the period January 1, 1990 to June 1, 2009, returned 62 references. Abstracts that did not deal primarily with SAH and potential markers in the CSF of humans were excluded, resulting in 27 abstracts. Only articles providing sufficient information for a substantiated analysis were selected. In addition, articles identified in reference lists of individual articles were selected if considered appropriate. Evidence was classified as class I-IV and recommendations were classified as category A-C according to European Federation of Neurological Societies guidelines. We evaluated CSF markers in SAH patients and divided them into 3 categories: A, markers with auspicious value; B, candidate markers; and C, noncandidate markers. Category A markers included tumor necrosis factor (TNF)-α, soluble tumor necrosis factor receptor I (sTNFR-I), and interleukin (IL)-1 receptor antagonist (IL-1ra), as well as the neurofilament proteins NFL and NfH. Category B markers included apolipoprotein E (ApoE), F2-isoprostane (F2-IsoP), NOx, and the indicators for thrombin activity membrane-bound tissue factor (mTF) and thrombin-antithrombin III complex (TAT) for neurologic outcome prediction, as well as E-selectin, lactate, alpha-II spectrin breakdown products (SBDPs), asymmetric dimethyl-L-arginine (ADMA), and monocyte chemoattractant protein-1 (MCP-1) for vasospasm prognostication. Category C markers included S100B, platelet-derived growth factor (PDGF), YKL-40, chitotriosidase, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and IL-8. Cytokines and their receptors, as well as neuronal intracellular proteins, seem to be potential markers for outcome determination in patients after SAH.

Biomarkers and vasospasm after aneurysmal subarachnoid hemorrhage

Subarachnoid hemorrhage from the rupture of a saccular aneurysm is a devastating neurological disease that has a high morbidity and mortality not only from the initial hemorrhage, but also from the delayed complications, such as cerebral vasospasm. Cerebral vasospasm can lead to delayed ischemic injury 1 to 2 weeks after the initial hemorrhage. Although the pathophysiology of vasospasm has been described for decades, the molecular basis remains poorly understood. With the many advances in the past decade in the development of sensitive molecular biological techniques, imaging, biochemical purification, and protein identification, new insights are beginning to reveal the etiology of vasospasm. These findings will not only help to identify markers of vasospasm and prognostic outcome, but will also yield potential therapeutic targets for the treatment of this disease. This review focuses on the methods available for the identification of biological markers of vasospasm and their limitations, the current understanding as to the utility and prognostic significance of identified biomarkers, the utility of these biomarkers in predicting vasospasm and outcome, and future directions of research in this field.

Elevated cerebrospinal fluid and serum YKL-40 levels are not associated with symptomatic vasospasm in patients with aneurysmal subarachnoid haemorrhage

YKL-40 is a newly discovered matrix protein that is thought to be released during the acute stages of inflammation. It has recently been speculated that YKL-40 may serve as a specific serological marker of neutrophil function at the site of tissue inflammation. Our aim was to determine whether the levels of YKL-40 in both the cerebrospinal fluid and sera of 22 patients with aneurysmal subarachnoid haemorrhage were associated with either vasospasm or outcome. The levels were also compared with those of 16 control patients with hydrocephalus. We found that patients with aneurysmal subarachnoid haemorrhage had significantly higher YKL-40 levels in both cerebrospinal fluid and serum than controls. However, elevated YKL-40 levels were not associated with symptomatic vasospasm or 6-month outcome. We show that elevated YKL-40 levels are not correlated with the severity of subarachnoid haemorrhage and cannot be used as a serological marker of inflammation in patients with an aneurysm rupture.

Detection of caspase-3, neuron specific enolase, and high-sensitivity C-reactive protein levels in both cerebrospinal fluid and serum of patients after aneurysmal subarachnoid hemorrhage

OBJECTIVE

The purpose of this study is to explore whether or not the levels of caspase-3 (Casp3), neuron-specific enolase (NSE), and high-sensitivity C-reactive protein (hsCRP) were elevated in cerebrospinal fluid (CSF) and serum of patients after aneurysmal subarachnoid hemorrhage (SAH).

METHODS

This prospective clinical study consisted of 20 patients who experienced recent aneurysmal SAH and 15 control patients who experienced hydrocephalus without any other central nervous system disease. CSF and serum samples obtained within the first 3 days, and on the fifth and seventh days of SAH were assayed for Casp3, NSE, and hsCRP by using enzyme-linked immunosorbent assay.

RESULTS

Levels of Casp3, NSE, and hsCRP in the CSF (P = 0.00001, P = 0.00001, and P <0.003, respectively) and in the serum (P = 0.00001, P <0.01, and P = 0.00001, respectively) of SAH patients were found to be elevated when compared with controls with normal pressure hydrocephalus.

CONCLUSION

The authors have demonstrated the synchronized elevation of Casp3, NSE, and hsCRP in both CSF and serum of patients with aneurysmal SAH. Further studies with a large number of patients are recommended to more accurately determine the roles of these molecules in aneurysmal SAH.