Release of glial fibrillary acidic protein is related to the neurovascular status in acute ischemic stroke

Expression of Acidic Fibrillar Protein and Neuroglobin in Thrombolytic Patients in Ischemic Stroke

Purpose

Glial fibrillary acidic protein (GFAP) and neuroglobin (NGB) are important biomarkers of cerebral hypoxia. For this reason, an attempt was made to assess their concentrations in various time intervals and their impact on the severity of neurological symptoms and functional prognosis of thrombolytic ischemic stroke patients.

Patients and Methods

The study involved 94 patients reporting to the emergency department of the Collegium Medicum University Hospital in Bydgoszcz within < 4.5 hours of the onset of stroke symptoms. GFAP and neuroglobin levels were measured in plasma at indicated times using a commercial ELISA kit.

Results

Based on the data gathered, statistically significant differences were found between the concentration of biomarkers in stroke patients and the control group. The concentrations of both biomarkers, GFAP and NGB, were elevated in patients after ischemic stroke and the changes in their concentrations in the subsequent stages of stroke may suggest their prognostic value strictly dependent on time. NGB was determined on the 7th day, and mRS - after a year (0.35). GFAP measured after 24 h and on day 7 could be a promising biomarker of functional outcome after one year (cut-off point ≤ 0.231 ng/mL, sensitivity 75.0%, specificity 61.2%, cut off point ≤ 0.235 ng/mL, sensitivity 75.0%, specificity 73.9%, respectively) and the severity of the patient's neurological condition. At GFAP concentrations above 0.25 ng/mL, measured within 24 hours, a sharp increase in mortality was observed in stroke patients. In the case of NGB, at the time of stroke occurrence (14 ng/mL) and after 24 hours (10-60 ng/mL). Differences in the concentrations of these biomarkers have been demonstrated in different stroke subtypes.

Conclusion

NGB and GFAP are important biomarkers of ischemic brain injury and may also participate in predicting neurological outcomes.

Incremental value of serum neurofilament light chain and glial fibrillary acidic protein as blood-based biomarkers for predicting functional outcome in severe acute ischemic stroke

INTRODUCTION

Blood-based biomarkers may improve prediction of functional outcome in patients with acute ischemic stroke. The role of neurofilament light chain (NfL) and glial fibrillary acidic (GFAP) as potential biomarkers especially in severe stroke patients is unknown.

PATIENTS AND METHODS

Prospective, monocenter, cohort study including consecutive patients with severe ischemic stroke in the anterior circulation on admission (NIHSS score ⩾ 6 points or indication for mechanical thrombectomy). Outcome was assessed 3 months after the index stroke by the modified Rankin Scale (mRS). Serum biomarkers levels of NfL and GFAP were determined by ultrasensitive ELISA. Univariate and multivariate logistic regression models were performed to determine the association of biomarker levels and functional disability. Discrimination, calibration, and overall performance were analyzed in different models via AUROC, calibration plots (with Emax and Eavg), Brier-score and R2 using variables, identified as important covariates for functional outcome in previous studies.

RESULTS

Between 06/2020 and 08/2021, 213 patients were included [47% female, mean age 76 (SD ± 12) years, median NIHSS score 13 (interquartile range, IQR 9; 17)]. Biomarker serum levels were measured at a median of 1 [IQR, 1; 2] day after admission. Compared to patients with mRS 0-2 at 3 months, patients with mRS 3-6 had higher serum levels of NfL (median: 136 pg/ml vs 41 pg/ml; p < 0.0001) and GFAP (700 ng/ml vs 9.6 ng/ml; p < 0.0001). Both biomarkers were significantly associated with functional outcome [adjusted logistic regression, odds ratio (95% CI) for NfL: 2.63 (1.62; 4.56), GFAP: 2.16 (1.58; 3.09)]. In all models the addition of serum NfL led to a significant improvement in the AUROC, as did the addition of serum GFAP. Calibration plots showed high agreement between the predicted and observed outcomes and after addition of the two blood-based biomarkers there was an improvement of the overall performance.

CONCLUSION

Prediction of functional outcome after severe acute ischemic stroke was improved by the blood-based biomarkers serum NfL and GFAP, measured in the acute phase of stroke. These findings have to be replicated in independent external cohorts.Study registration: DRKS00022064.

Brain Injury Biomarkers and Applications in Neurological Diseases

ABSTRACT

Neurological diseases are a major health concern, and brain injury is a typical pathological process in various neurological disorders. Different biomarkers in the blood or the cerebrospinal fluid are associated with specific physiological and pathological processes. They are vital in identifying, diagnosing, and treating brain injuries. In this review, we described biomarkers for neuronal cell body injury (neuron-specific enolase, ubiquitin C-terminal hydrolase-L1, αII-spectrin), axonal injury (neurofilament proteins, tau), astrocyte injury (S100β, glial fibrillary acidic protein), demyelination (myelin basic protein), autoantibodies, and other emerging biomarkers (extracellular vesicles, microRNAs). We aimed to summarize the applications of these biomarkers and their related interests and limits in the diagnosis and prognosis for neurological diseases, including traumatic brain injury, status epilepticus, stroke, Alzheimer's disease, and infection. In addition, a reasonable outlook for brain injury biomarkers as ideal detection tools for neurological diseases is presented.

Impact of repeated sportive chokes on carotid intima media thickness and brain injury biomarkers in grappling athletes

PURPOSE

Vascular neck compression techniques, referred to as 'chokes' in combat sports, reduce cerebral perfusion, causing loss of consciousness or voluntary submission by the choked athlete. Despite these chokes happening millions of times yearly around the world, there is scant research on their long-term effects. This pilot study evaluated whether repeated choking in submission grappling impacts the carotid intima media thickness (CIMT) and brain injury biomarkers (NFL, hGFAP, t-Tau, and UCH-L1).

METHODS

Participants (n = 39, 29 male; ages 27-60 years) were assigned to one of two study arms: Grapplers (n = 20, 15 male) and 19 age/sex/body size matched controls. Grapplers had been exposed to >500 choke events while training for >5 years in a choke-inclusive sport. Exclusion criteria were recent TBI or deficits from a past TBI or stroke. Bilateral ultrasound measurement of the CIMT was performed, and blood was collected for quantitative analysis of four brain injury markers. Subgroup analyses were performed within the Grappler group to account for blunt head trauma as a possible confounder.

RESULTS

There was no overall difference in CIMT measurements between Grapplers (mean 0.55 mm, SD 0.07) and Controls (mean 0.57 mm, SD 0.10) p = 0.498 [95% CI -0.04-0.08], nor were there CIMT differences between Grappler subgroups of blunt Trauma and No-Trauma. There were no significant differences in any biomarkers comparing Grapplers and Controls or comparing Grappler subgroups of Trauma and No-Trauma.

CONCLUSION

This study found no significant difference in CIMT and serum brain injury biomarkers between controls and grapplers with extensive transient choke experience, nor between grapplers with extensive past blunt head trauma and those without.

Monitoring of cerebral blood flow autoregulation: physiologic basis, measurement, and clinical implications

Cerebral blood flow (CBF) autoregulation is the physiologic process whereby blood supply to the brain is kept constant over a range of cerebral perfusion pressures ensuring a constant supply of metabolic substrate. Clinical methods for monitoring CBF autoregulation were first developed for neurocritically ill patients and have been extended to surgical patients. These methods are based on measuring the relationship between cerebral perfusion pressure and surrogates of CBF or cerebral blood volume (CBV) at low frequencies (<0.05 Hz) of autoregulation using time or frequency domain analyses. Initially intracranial pressure monitoring or transcranial Doppler assessment of CBF velocity was utilised relative to changes in cerebral perfusion pressure or mean arterial pressure. A more clinically practical approach utilising filtered signals from near infrared spectroscopy monitors as an estimate of CBF has been validated. In contrast to the traditional teaching that 50 mm Hg is the autoregulation threshold, these investigations have found wide interindividual variability of the lower limit of autoregulation ranging from 40 to 90 mm Hg in adults and 20-55 mm Hg in children. Observational data have linked impaired CBF autoregulation metrics to adverse outcomes in patients with traumatic brain injury, ischaemic stroke, subarachnoid haemorrhage, intracerebral haemorrhage, and in surgical patients. CBF autoregulation monitoring has been described in both cardiac and noncardiac surgery. Data from a single-centre randomised study in adults found that targeting arterial pressure during cardiopulmonary bypass to above the lower limit of autoregulation led to a reduction of postoperative delirium and improved memory 1 month after surgery compared with usual care. Together, the growing body of evidence suggests that monitoring CBF autoregulation provides prognostic information on eventual patient outcomes and offers potential for therapeutic intervention. For surgical patients, personalised blood pressure management based on CBF autoregulation data holds promise as a strategy to improve patient neurocognitive outcomes.

GFAP as Astrocyte-Derived Extracellular Vesicle Cargo in Acute Ischemic Stroke Patients-A Pilot Study

The utility of serum glial fibrillary acidic protein (GFAP) in acute ischemic stroke (AIS) has been extensively studied in recent years. Here, we aimed to assess its potential role as a cargo protein of extracellular vesicles (EVs) secreted by astrocytes (ADEVs) in response to brain ischemia. Plasma samples from eighteen AIS patients at 24 h (D1), 7 days (D7), and one month (M1) post-symptoms onset, and nine age, sex, and cardiovascular risk factor-matched healthy controls were obtained to isolate EVs using the Exoquick ULTRA EV kit. Subsets of presumed ADEVs were identified further by the expression of the glutamate aspartate transporter (GLAST) as a specific marker of astrocytes with the Basic Exo-Flow Capture kit. Western blotting has tested the presence of GFAP in ADEV cargo. Post-stroke ADEV GFAP levels were elevated at D1 and D7 but not M1 compared to controls (p = 0.007, p = 0.019, and p = 0.344, respectively). Significant differences were highlighted in ADEV GFAP content at the three time points studied (n = 12, p = 0.027) and between D1 and M1 (z = 2.65, p = 0.023). A positive correlation was observed between the modified Rankin Scale (mRS) at D7 and ADEV GFAP at D1 (r = 0.58, p = 0.010) and D7 (r = 0.57, p = 0.013), respectively. ADEV GFAP may dynamically reflect changes during the first month post-ischemia. Profiling ADEVs from peripheral blood could provide a new way to assess the central nervous system pathology.

Prediction of clinical progression in nervous system diseases: plasma glial fibrillary acidic protein (GFAP)

Glial fibrillary acidic protein (GFAP), an intracellular type III intermediate filament protein, provides structural support and maintains the mechanical integrity of astrocytes. It is predominantly found in the astrocytes which are the most abundant subtypes of glial cells in the brain and spinal cord. As a marker protein of astrocytes, GFAP may exert a variety of physiological effects in neurological diseases. For example, previous published literatures showed that autoimmune GFAP astrocytopathy is an inflammatory disease of the central nervous system (CNS). Moreover, the studies of GFAP in brain tumors mainly focus on the predictive value of tumor volume. Furthermore, using biomarkers in the early setting will lead to a simplified and standardized way to estimate the poor outcome in traumatic brain injury (TBI) and ischemic stroke. Recently, observational studies revealed that cerebrospinal fluid (CSF) GFAP, as a valuable potential diagnostic biomarker for neurosyphilis, had a sensitivity of 76.60% and specificity of 85.56%. The reason plasma GFAP could serve as a promising biomarker for diagnosis and prediction of Alzheimer's disease (AD) is that it effectively distinguished AD dementia from multiple neurodegenerative diseases and predicted the individual risk of AD progression. In addition, GFAP can be helpful in differentiating relapsing-remitting multiple sclerosis (RRMS) versus progressive MS (PMS). This review article aims to provide an overview of GFAP in the prediction of clinical progression in neuroinflammation, brain tumors, TBI, ischemic stroke, genetic disorders, neurodegeneration and other diseases in the CNS and to explore the potential therapeutic methods.

Nesfatin-1: A Biomarker and Potential Therapeutic Target in Neurological Disorders

Nesfatin-1 is a novel adipocytokine consisting of 82 amino acids with anorexic and anti-hyperglycemic properties. Further studies of nesfatin-1 have shown it to be closely associated with neurological disorders. Changes in nesfatin-1 levels are closely linked to the onset, progression and severity of neurological disorders. Nesfatin-1 may affect the development of neurological disorders and can indicate disease evolution and prognosis, thus informing the choice of treatment options. In addition, regulation of the expression or level of nesfatin-1 can improve the level of neuroinflammation, apoptosis, oxidative damage and other indicators. It is demonstrated that nesfatin-1 is involved in neuroprotection and may be a therapeutic target for neurological disorders. In this paper, we will also discuss the role of nesfatin-1 as a biomarker in neurological diseases and its potential mechanism of action in neurological diseases, providing new ideas for the diagnosis and treatment of neurological diseases.

GFAP and UCHL1 in Non-traumatic SAH: The Story thus Far. A Systematic Review of the Literature

OBJECTIVE

Non-traumatic subarachnoid hemorrhage (SAH) is associated with a high percentage of misdiagnosis and poor prognosis. Biomarkers could be useful in the identification, treatment/management guidance, and outcome improvement of SAH patients. The current systematic review aims to investigate the potential role of biomarkers GFAP (Glial Fibrillary Acidic Protein) and UCH-L1 (Ubiquitin C-Terminal Hydrolase L1) in the diagnosis and prognosis of non-traumatic SAH.

METHODS

A systematic search of PubMed, Scopus, and Web of Science databases was conducted from their inception through February 2023.

RESULTS

17 studies met the inclusion criteria and were included in this review. The vast majority of the included studies (82%) were on GFAP. Most studies used blood and/or CSF samples and incorporated multiple measurements through the initial hospitalization days. The majority of identified studies reported significantly higher levels of GFAP and UCHL1 in SAH patients with poor outcomes. There was notable variation in the specimen type and the timing of sampling.

CONCLUSION

Quantification of GFAP and UCHL1 through the initial days of hospitalization shows promise in the prediction of SAH patient outcomes. Further research is nevertheless warranted to confirm these findings and further clarify the use of the two biomarkers in SAH diagnosis and the prediction of severity and secondary events.

Brain-derived Tau for Monitoring Brain Injury in Acute Ischemic Stroke

The evolution of infarcts varies widely among patients with acute ischemic stroke (IS) and influences treatment decisions. Neuroimaging is not applicable for frequent monitoring and there is no blood-based biomarker to track ongoing brain injury in acute IS. Here, we examined the utility of plasma brain-derived tau (BD-tau) as a biomarker for brain injury in acute IS. We conducted the prospective, observational Precision Medicine in Stroke [PROMISE] study with serial blood sampling upon hospital admission and at days 2, 3, and 7 in patients with acute ischemic stroke (IS) and for comparison, in patients with stroke mimics (SM). We determined the temporal course of plasma BD-tau, its relation to infarct size and admission imaging-based metrics of brain injury, and its value to predict functional outcome. Upon admission (median time-from-onset, 4.4h), BD-tau levels in IS patients correlated with ASPECTS (ρ=-0.21, P<.0001) and were predictive of final infarct volume (ρ=0.26, P<.0001). In contrast to SM patients, BD-tau levels in IS patients increased from admission (median, 2.9 pg/ml [IQR, 1.8-4.8]) to day 2 (median time-from-onset, 22.7h; median BD-tau, 5.0 pg/ml [IQR, 2.6-10.3]; P<.0001). The rate of change of BD-tau from admission to day 2 was significantly associated with collateral supply (R2=0.10, P<.0001) and infarct progression (ρ=0.58, P<.0001). At day 2, BD-tau was predictive of final infarct volume (ρ=0.59, P<.0001) and showed superior value for predicting the 90-day mRS score compared with final infarct volume. In conclusion, in 502 patients with acute IS, plasma BD-tau was associated with imaging-based metrics of brain injury upon admission, increased within the first 24 hours in correlation with infarct progression, and at 24 hours was superior to final infarct volume in predicting 90-day functional outcome. Further research is needed to determine whether BD-tau assessments can inform decision-making in stroke care.

Glial Fibrillary Acidic Protein Levels in Post-Stroke Depression: A Prospective Ischemic Stroke Cohort

Background and Purpose

Increased glial fibrillary acidic protein (GFAP) levels were found in cerebrovascular disease patients. The pathogenesis of depression after ischemic stroke remains largely unknown. Here, we aim to determine whether GFAP concentrations were associated with post-stroke depression (PSD) at 3 months.

Methods

From March 2022 to September 2022, patients with first-ever ischemic stroke were prospectively recruited. GFAP concentrations were detected within 24 h using an enzyme-linked immunosorbent assay. The PSD was defined as a Hamilton Depression Rating Scale 24-Item score ≥ 8.

Results

A total of 206 subjects with ischemic stroke (mean age: 63.6 years; 49.0% female) were enrolled. During the 90-day follow-up, 57 participants (27.7%) were observed in PSD. The median serum GFAP concentrations were 0.67 ng/mL. After adjustment for the covariates, higher increased GFAP levels were associated with increased risk of PSD (odds ratio [OR], 7.12; 95% confidence interval [CI], 3.29-15.44; P < 0.001). Also, the multivariate-adjusted OR of PSD associated with the fourth quartile of GFAP was 10.89 (95% CI, 3.53-33.60; P < 0.001) compared with the first quartile. Furthermore, the restricted cubic spline confirmed a linear association between GFAP and the risk of PSD (P for linearity < 0.001).

Conclusion

Our results indicated that increased circulating GFAP concentrations were significantly correlated with the risk of PSD at 3 months. Measuring the GFAP levels after ischemic stroke may add some values for the risk stratifying of PSD.

Blood-Based Biomarkers for Neuroprognostication in Acute Brain Injury

Acute brain injury causes loss of functionality in patients that often is devastating. Predicting the degree of functional loss and overall prognosis requires a multifaceted approach to help patients, and more so their families, make important decisions regarding plans and goals of care. A variety of blood-based markers have been studied as one aspect of this determination. In this review, we discuss CNS-derived and systemic markers that have been studied for neuroprognostication purposes. We discuss the foundation of each protein, the conditions in which it has been studied, and how the literature has used these markers for interpretation. We also discuss challenges to using each marker in each section as well.

Quantification and prospective evaluation of serum NfL and GFAP as blood-derived biomarkers of outcome in acute ischemic stroke patients

Identification of reliable and accessible biomarkers to characterize ischemic stroke patients' prognosis remains a clinical challenge. Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) are markers of brain injury, detectable in blood by high-sensitive technologies. Our aim was to measure serum NfL and GFAP after stroke, and to evaluate their correlation with functional outcome and the scores in rehabilitation scales at 3-month follow-up. Stroke patients were prospectively enrolled in a longitudinal observational study within 24 hours from symptom onset (D1) and monitored after 7 (D7), 30 ± 3 (M1) and 90 ± 5 (M3) days. At each time-point serum NfL and GFAP levels were measured by Single Molecule Array and correlated with National Institute of Health Stroke Scale (NIHSS), modified Rankin scale (mRS), Trunk Control Test (TCT), Functional Ambulation Classification (FAC) and Functional Independence Measure (FIM) scores. Serum NfL and GFAP showed different temporal profiles: NfL increased after stroke with a peak value at D7; GFAP showed an earlier peak at D1. NfL and GFAP concentrations correlated with clinical/rehabilitation outcomes both longitudinally and prospectively. Multivariate analysis revealed that NfL-D7 and GFAP-D1 were independent predictors of 3-month NIHSS, TCT, FAC and FIM scores, with NfL being the biomarker with the best predictive performance.

Secondary neurodegeneration following Stroke: what can blood biomarkers tell us?

Stroke is one of the leading causes of death and the primary source of disability in adults, resulting in neuronal necrosis of ischemic areas, and in possible secondary degeneration of regions surrounding or distant to the initial damaged area. Secondary neurodegeneration (SNDG) following stroke has been shown to have different pathogenetic origins including inflammation, neurovascular response and cytotoxicity, but can be associated also to regenerative processes. Aside from focal neuronal loss, ipsilateral and contralateral effects distal to the lesion site, disruptions of global functional connectivity and a transcallosal diaschisis have been reported in the chronic stages after stroke. Furthermore, SNDG can be observed in different areas not directly connected to the primary lesion, such as thalamus, hippocampus, amygdala, substantia nigra, corpus callosum, bilateral inferior fronto-occipital fasciculus and superior longitudinal fasciculus, which can be highlighted by neuroimaging techniques. Although the clinical relevance of SNDG following stroke has not been well understood, the identification of specific biomarkers that reflect the brain response to the damage, is of paramount importance to investigate in vivo the different phases of stroke. Actually, brain-derived markers, particularly neurofilament light chain, tau protein, S100b, in post-stroke patients have yielded promising results. This review focuses on cerebral morphological modifications occurring after a stroke, on associated cellular and molecular changes and on state-of-the-art of biomarkers in acute and chronic phase. Finally, we discuss new perspectives regarding the implementation of blood-based biomarkers in clinical practice to improve the rehabilitation approaches and post stroke recovery.

Biomarkers and the outcomes of ischemic stroke

Biomarkers are measurable substances that could be used as objective indicators for disease diagnosis, responses to treatments, and outcomes predictions. In this review, we summarized the data on a number of important biomarkers including glutamate, S100B, glial fibrillary acidic protein, receptor for advanced glycation end-products, intercellular adhesion molecule-1, von willebrand factor, matrix metalloproteinase-9, interleukin-6, tumor necrosis factor-a, activated protein C, copeptin, neuron-specific enolase, tau protein, gamma aminobutyric acid, blood glucose, endothelial progenitor cells, and circulating CD34-positive cells that could be potentially used to indicate the disease burden and/or predict clinical outcome of ischemic stroke. We examined the relationship between specific biomarkers and disease burden and outcomes and discussed the potential mechanisms underlying the relationship. The clinical significance and implications of these biomarkers were also discussed.

Diagnostic performance of Glial Fibrillary Acidic Protein and Prehospital Stroke Scale for identification of stroke and stroke subtypes in an unselected patient cohort with symptom onset < 4.5 h

INTRODUCTION

Rapid identification and treatment of stroke is crucial for the outcome of the patient. We aimed to determine the performance of glial fibrillary acidic protein (GFAP) independently and in combination with the Prehospital Stroke Score (PreSS) for identification and differentiation of acute stroke within 4.5 h after symptom onset.

PATIENTS AND METHODS

Clinical data and serum samples were collected from the Treat-Norwegian Acute Stroke Prehospital Project (Treat-NASPP). Patients with suspected stroke and symptoms lasting ≤ 4.5 h had blood samples collected and were evaluated with the National Institutes of Health Stroke Scale prospectively. In this sub study, NIHSS was retrospectively translated into PreSS and GFAP was measured using the sensitive single molecule array (SIMOA).

RESULTS

A total of 299 patients with suspected stroke were recruited from Treat-NASPP and included in this study (44% acute ischemic stroke (AIS), 10% intracranial hemorrhage (ICrH), 7% transient ischemic attack (TIA), and 38% stroke mimics). ICrH was identified with a cross-fold validated area under the receiver-operating characteristic curve (AUC) of 0.73 (95% CI 0.62-0.84). A decision tree with PreSS and GFAP combined, first identified patients with a low probability of stroke. Subsequently, GFAP detected patients with ICrH with a 25.0% sensitivity (95% CI 11.5-43.4) and 100.0% specificity (95% CI 98.6-100.0). Lastly, patients with large-vessel occlusion (LVO) were detected with a 55.6% sensitivity (95% CI 35.3-74.5) and 82.4% specificity (95% CI 77.3-86.7).

CONCLUSION

In unselected patients with suspected stroke, GFAP alone identified ICrH. Combined in a decision tree, GFAP and PreSS identified subgroups with high proportions of stroke mimics, ICrH, LVO, and AIS (non-LVO strokes).

[Serum brain damage biomarkers as a diagnostic and prognostic tool in ischemic stroke]

OBJECTIVE

To study serum quantities of neuron specific enolase (NSE), glial fibrillary acidic protein (GFAP) and NR2-antibodies (NR2-ab) in various cerebrovascular pathology and assess their value as a panel used as a diagnostic and predictive tool for stroke.

MATERIAL AND METHODS

NSE, GFAP and NR2-ab serum levels were measured twice for 84 patients with ischemic stroke (IS) and 8 patients with hemorrhagic stroke (HI), once for 8 patients with transient ischemic attack (TIA), 26 patients with chronic brain ischemia (CBI), 27 healthy volunteers (HV).

RESULTS

NSE and GFAP levels were significantly higher in IS than in CBI and HV patients, and NR2-ab levels in IS were higher than in TIA and lower than in HV. In patients with more pronounced neurological deficiency and less favorable functional outcome by day 10-14 of IS, the levels of NSE, GFAP and NR2-ab were higher. Sensitivity and specificity of biomarker panel was higher than with their separate application.

CONCLUSION

The NSE, GFAP and NR2-ab biomarkers have a diagnostic and predictive value for IS.

Higher serum PGE2 is a predicative biomarker for postoperative delirium following elective orthopedic surgery in elderly patients

Background

Postoperative delirium (POD), one of the most common complications following major surgery, imposes a heavy burden on patients and society. The objective of this exploratory study was to conduct a secondary analysis to identify whether there exist novel and reliable serum biomarkers for the prediction of POD.

Methods

A total of 131 adult patients (≥ 65 years) undergoing lower extremity orthopedic surgery with were enrolled in this study. Cognitive function was assessed preoperatively with Mini-Mental State Examination (MMSE). Delirium was diagnosed according to the Confusion Assessment Method (CAM) criteria on preoperative day and postoperative days 1–3. The preoperative serum levels of a panel of 16 biochemical parameters were measured by ELISA.

Results

Thirty-five patients developed POD, with an incidence of 26.7%. Patients in POD group were older (P = 0.001) and had lower preoperative MMSE scores (P = 0.001). Preoperative serum levels of prostaglandin E2 (PGE2, P < 0.001), S100β (P < 0.001), glial fibrillary acidic protein (P < 0.001) and neurofilament light (P = 0.002) in POD group were significantly increased. Logistic regression analysis showed that advanced age (OR = 1.144, 95%CI: 1.008 ~ 1.298, P = 0.037), higher serum neurofilament light (OR = 1.003, 95%CI: 1.000 ~ 1.005, P = 0.036) and PGE2 (OR = 1.031, 95%CI: 1.018 ~ 1.044, P < 0.001) levels were associated with the development of POD. In addition, serum level of PGE2 yielded an area under the ROC curve (AUC) of 0.897 to predict POD (P < 0.001), with a sensitivity of 80% and a specificity of 83.3%.

Conclusions

Our study showed that higher preoperative serum PGE2 level might be a biomarker to predict the occurrence of POD in elderly patients undergoing elective orthopedic surgery.

Trial registration

NCT03792373 www.clinicaltrials.gov.

Fluid biomarkers in stroke: From animal models to clinical care

Stroke is a leading cause of death and disability worldwide. Stroke prevention, early diagnosis, and efficient acute treatment are priorities to successfully impact stroke death and disability. Fluid biomarkers may improve stroke differential diagnostic, patient stratification for acute treatment, and post-stroke individualized rehabilitation. In the present work, we characterized the use of stroke animal models in fluid biomarker research through a systematic review of PubMed and Scopus databases, followed by a literature review on the translation to the human stroke care setting and future perspectives in the field. We found increasing numbers of publications but with limited translation to the clinic. Animal studies are very heterogeneous, do not account for several human features present in stroke, and, importantly, only a minority of such studies used human cohorts to validate biomarker findings. Clinical studies have found appealing candidates, both protein and circulating nucleic acids, to contribute to a more personalized stroke care pathway. Still, brain tissue complexity and the fact that different brain pathologies share lesion biomarkers make this task challenging due to biomarker low specificity. Moreover, the study design and lack of validation cohorts may have precluded a formal integration of biomarkers in different steps of stroke diagnosis and treatment. To overcome such issues, recent pivotal studies on biomarker dynamics in individual patients are providing added value to diagnosis and anticipating patients' early prognosis. Presently, the most consistent protein biomarkers for stroke diagnosis and short- and long-term prognosis are associated with tissue damage at neuronal (TAU), axonal (NFL), or astroglial (GFAP and S100β) levels. Most promising nucleic acids are microRNAs (miR), due to their stability in plasma and ease of access. Still, clinical validation and standardized quantitation place them a step behind compared protein as stroke biomarkers. Ultimately, the definition of clinically relevant biomarker panels and optimization of fast and sensitive biomarker measurements in the blood, together with their combination with clinical and neuroimaging data, will pave the way toward personalized stroke care.

Glial Fibrillary Acidic Protein (GFAP): Neuroinflammation Biomarker in Acute Ischemic Stroke

Introduction

Blockage of the cerebral arteries due to thrombosis and embolism resulting in decreased blood flow to the brain, reduced oxygen supply to the brain, resulting in neuronal damage and causes astrocyte cells to secrete glial fibrillary acidic protein (GFAP). The objective of this study was to determine the correlation between GFAP levels serum and clinical outcome in patients with acute ischemic stroke.

Methods

This was observational with a cross-sectional design on acute ischemic stroke patients confirmed by CT scans and divided into large vessel occlusion and small-vessel occlusion. Clinical outcome was measured using the National Institutional Health Stroke Scale (NIHSS) tool. Statistical analysis uses Spearman’s rank correlation test and Mann Whitney’s test, significant if p < 0.05.

Results

After collecting 33 research subjects, we found 16 people with large vessel occlusion and 17 people with small vessel occlusion. Serum GFAP levels were 0.2–1.9 ng/mL, 9.1% with a mild neurological deficit, 45.45% were moderate neurological deficits, and 45.45% were severe neurological deficits. There was a significant positive correlation (r = 0.522; p = 0.002) between serum GFAP levels and the degree of neurological deficit in ischemic stroke patients. There was a statistically significant difference between serum GFAP levels in ischemic stroke patients with CT scan results of large artery occlusion compared to small artery occlusion (0.7 vs 0.4ng/mL; p = 0.001).

Conclusion

There was a positive correlation between GFAP level serum and NIHSS score on acute ischemic stroke. The higher the value of GFAP serum level, the higher the value for NIHSS and correlated with stroke severity and the extent of brain damage in ischemic stroke patients.

Role of S100B Serum Concentration as a Surrogate Outcome Parameter After Mechanical Thrombectomy

Background and Objectives

To establish serum concentration of protein S100B as an objective biomarker surrogate for astroglial tissue damage after mechanical thrombectomy in patients with acute ischemic stroke.

Methods

This prospective 2-center study recruited patients with acute middle cerebral artery infarctions caused by large vessel occlusion treated with mechanical thrombectomy. Blood samples were collected at day 2 after intervention and analyzed for S100B serum concentrations using ELISA techniques. Infarct size was determined on follow-up brain imaging and functional outcome according to modified Rankin Scale (mRS) was assessed at 90 days.

Results

A total of 171 patients were included (mean age ± SD: 70 ± 14 years, 42% female). S100B levels correlated with infarct size. Median S100B concentrations at day 2 after intervention were lower in patients with favorable outcome (mRS score 0–1) at 90 days compared to patients with unfavorable outcome (mRS score 2–6) (median 0.10 µg/L [interquartile range 0.07–0.14] vs 0.20 µg/L [0.11–0.48], p < 0.001). Younger age (odds ratio [OR] 1.120 [confidence interval (CI) 1.068–1.174]; p < 0.001), lower National Institutes of Health Stroke Scale score 24 hours after symptom onset (OR 1.232 [CI 1.106–1.372]; p < 0.001), and lower S100B serum concentrations (OR 1.364 [CI 1.105–1.683]; p = 0.004) were independently associated with a favorable outcome. S100B was able to eliminate the lateralization bias associated with the use of mRS for functional outcome assessment at 90 days after stroke.

Discussion

S100B serum concentrations after mechanical thrombectomy indicate the extent of ischemic tissue damage. This can be assessed rapidly, independent of brain imaging and clinical outcome scales. Following prospective validation in further studies, this may provide an objective surrogate outcome measure both in clinical routine and interventional trials.

Classification of Evidence

This study provides Class I evidence that S100B 2 days following mechanical thrombectomy for acute ischemic stroke accurately distinguishes favorable from unfavorable functional outcome.

Diagnostic Accuracy of Glial Fibrillary Acidic Protein and Ubiquitin Carboxy-Terminal Hydrolase-L1 Serum Concentrations for Differentiating Acute Intracerebral Hemorrhage from Ischemic Stroke

BACKGROUND

Biomarkers indicative of intracerebral hemorrhage (ICH) may help triage acute stroke patients in the pre-hospital phase. We hypothesized that serum concentration of glial fibrillary acidic protein (GFAP) in combination with ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1), measured by a rapid bio-assay, could be used to distinguish ICH from ischemic stroke.

METHODS

This prospective two-center study recruited patients with a clinical diagnosis of acute stroke both in the pre-hospital phase and at hospital admission (within 4 and 6 h after symptom onset, respectively). Blood samples were analyzed for concentrations of GFAP and UCH-L1 using ELISA techniques. The reference standard was the diagnosis of ICH, ischemic stroke, or stroke mimicking condition achieved after clinical workup including brain imaging.

RESULTS

A total of 251 patients were included (mean age [± SD] 72 ± 15 years; 5 ICH, 23 ischemic strokes and 14 stroke mimics in the pre-hospital part; and 59 ICH, 148 ischemic strokes and 2 stroke mimics in the in-hospital part). Mean delay (± SD) from symptom onset to blood withdrawal was 130 ± 79 min for the pre-hospital patients and 136 ± 86 min for the in-hospital patients. Both GFAP and UCH-L1 serum concentrations were higher in patients having ICH as compared to other diagnoses (GFAP: median 330 ng/L [interquartile range 64-7060, range 8-56,100] vs. 27.5 ng/L [14-57.25, 0-781], p < 0.001; UCH-L1: 401 ng/L [265-764, 133-1812] vs. 338 ng/L [213-549.5, 0-2950], p = 0.025). Area-under-the-curve values were 0.866 (95% CI 0.809-0.924, p < 0.001) for GFAP, and 0.590 (0.511-0.670, p = 0.033) for UCH-L1. Regarding overall diagnostic accuracy, UCH-L1 did not add significantly to the performance of GFAP.

CONCLUSIONS

GFAP may differentiate ICH from ischemic stroke and stroke mimics. A point-of-care test to distinguish between ischemic and hemorrhagic strokes might facilitate triage to different treatment pathways or locations, or be used to select patients for trials of ultra-early interventions.

Serum glial fibrillary acidic protein and S100 calcium-binding protein B correlates cerebral vessel reactivity following carotid artery stenting

Using detection markers in serum has the advantages of simplicity, repeatability and the capability. This study combined the use of serum glial fibrillary acidic protein (GFAP) and S100B protein (S100B) with imaging tools to confirm the role of serum biomarkers in evaluating the cerebral vessel reactivity after carotid artery stenting (CAS). After CAS, the serum concentrations of GFAP and S100B increased to the peak at 24 h after operation, and then gradually decreased. The mean flow velocity (MFV) (pre-operation, post-operation, 30 days follow-up: 47.65 ± 17.24 cm/s, 62.37 ± 18.25 cm/s, 70.29 ± 16.89 cm/s; P < 0.05) and pulsatility index (PI) (pre-operation, post-operation, 30 days follow-up: 0.78 ± 0.21, 0.98 ± 0.19, 1.02 ± 0.20; P < 0.05) increased significantly in the ipsilateral middle cerebral artery after CAS. At the 30-day follow-up, the cerebrovascular reserve (CVR) (post-operation, 30 days follow-up: 27.47 ± 12.13 cm/s, 31.92 ± 10.94 cm/s; P < 0.05) improved significantly. In patients with different degrees of stenosis, the more severe the stenosis in the carotid artery, the more obvious the improvement of CVR at the 30 days of follow-up (CVR changes: 11.08 ± 7.95 cm/s, Kendall’s tau-b = 0.645, P < 0.001). And the serum concentrations of GFAP (r = − 0.629, P < 0.0001) and S100B (r = − 0.604, P < 0.0001) correlated negatively with CVR at 30 days after CAS. Therefore, we recommend using the biomarkers GFAP and S100B associated with imaging tools such as transcranial Doppler (TCD) and Magnetic resonance imaging (MRI) to evaluate the cerebral vessel reactivity following CAS.

Association between GFAP-positive astrocytes with clinically important parameters including neurological deficits and/or infarct volume in stroke-induced animals

The effect of GFAP-positive astrocytes, as positive or negative factors on stroke complications such as infarct volume and neurological deficits is currently under debate. This review was aimed to evaluate and compare the frequency of studies that showed a positive or negative relationship between astrocyte activation with the improvement of neurological deficits and/or the decrease of infarct volume. In addition, we reviewed two possible causes of differences in results including timepoint of stroke and stroke severity. Time of GFAP assessment was considered as time point and type of stroke induction and duration of stroke as stroke severity. According to our review in the most relevant English-language studies in the PubMed, Web of Science, and Google Scholar databases from 2005 to 2020, the majority of studies (77 vs. 28) showed a negative coincidence or correlation between GFAP-positive cells with neurological improvement as well as between GFAP-positive cells with infarct volume reduction. In most reviewed studies, GFAP expression was reported as a marker related to or coinciding with worse neurological function, or greater infarct volume. However, there were also studies that showed helpful effects of GFAP-positive cells on neurological function or stroke lesion. Although there are some elucidations that the difference in these findings is due to the time point of stroke and stroke severity, our review did not confirm these interpretations.

Monocytes carrying GFAP detect glioma, brain metastasis and ischaemic stroke, and predict glioblastoma survival

Diagnosis and monitoring of primary brain tumours, brain metastasis and acute ischaemic stroke all require invasive, burdensome and costly diagnostics, frequently lacking adequate sensitivity, particularly during disease monitoring. Monocytes are known to migrate to damaged tissues, where they act as tissue macrophages, continuously scavenging, phagocytizing and digesting apoptotic cells and other tissue debris. We hypothesize that upon completion of their tissue-cleaning task, these tissue macrophages might migrate via the lymph system to the bloodstream, where they can be detected and evaluated for their phagolysosomal contents. We discovered a blood monocyte subpopulation carrying the brain-specific glial fibrillary acidic protein in glioma patients and in patients with brain metastasis and evaluated the diagnostic potential of this finding. Blood samples were collected in a cross-sectional study before or during surgery from adult patients with brain lesions suspected of glioma. Together with blood samples from healthy controls, these samples were flowing cytometrically evaluated for intracellular glial fibrillary acidic protein in monocyte subsets. Acute ischaemic stroke patients were tested at multiple time points after onset to evaluate the presence of glial fibrillary acidic protein-carrying monocytes in other forms of brain tissue damage. Clinical data were collected retrospectively. High-grade gliomas (N = 145), brain metastasis (N = 21) and large stroke patients (>100 cm³) (N = 3 versus 6; multiple time points) had significantly increased frequencies of glial fibrillary acidic protein+CD16+ monocytes compared to healthy controls. Based on both a training and validation set, a cut-off value of 0.6% glial fibrillary acidic protein+CD16+ monocytes was established, with 81% sensitivity (95% CI 75–87%) and 85% specificity (95% CI 80–90%) for brain lesion detection. Acute ischaemic strokes of >100 cm³ reached >0.6% of glial fibrillary acidic protein+CD16+ monocytes within the first 2–8 h after hospitalization and subsided within 48 h. Glioblastoma patients with >20% glial fibrillary acidic protein+CD16+ non-classical monocytes had a significantly shorter median overall survival (8.1 versus 12.1 months). Our results and the available literature, support the hypothesis of a tissue-origin of these glial fibrillary acidic protein-carrying monocytes. Blood monocytes carrying glial fibrillary acidic protein have a high sensitivity and specificity for the detection of brain lesions and for glioblastoma patients with a decreased overall survival. Furthermore, their very rapid response to acute tissue damage identifies large areas of ischaemic tissue damage within 8 h after an ischaemic event. These studies are the first to report the clinical applicability for brain tissue damage detection through a minimally invasive diagnostic method, based on blood monocytes and not serum markers, with direct consequences for disease monitoring in future (therapeutic) studies and clinical decision making in glioma and acute ischaemic stroke patients.

Comparison of the effect of propofol and desflurane on S-100β and GFAP levels during controlled hypotension for functional endoscopic sinus surgery: A randomized controlled trial

BACKGROUND

Although surgical field visualization is important in functional endoscopic sinus surgery (FESS), the complications associated with controlled hypotension for surgery should be considered. Intraoperative hypotension is associated with postoperative stroke, leading to subsequent hypoxia with potential neurologic injury. We investigated the effect of propofol and desflurane anesthesia on S-100β and glial fibrillary acidic protein (GFAP) levels which are early biomarkers for cerebral ischemic change during controlled hypotension for FESS.

METHODS

For controlled hypotension during FESS, anesthesia was maintained with propofol/remifentanil in propofol group (n = 30) and with desflurane/remifentanil in desflurane group (n = 30). For S-100β and GFAP assay, blood samples were taken at base, 20 and 60 minutes after achieving the target range of mean arterial pressure, and at 60 minutes after surgery.

RESULTS

The base levels of S-100β were 98.04 ± 78.57 and 112.61 ± 66.38 pg/mL in the propofol and desflurane groups, respectively. The base levels of GFAP were 0.997 ± 0.486 and 0.898 ± 0.472 ng/mL in the propofol and desflurane groups, respectively. The S-100β and GFAP levels were significantly increased in the study period compared to the base levels in both groups (P ≤ .001). There was no significant difference at each time point between the 2 groups.

CONCLUSION

On comparing the effects of propofol and desflurane anesthesia for controlled hypotension on the levels of S-100β and GFAP, we noted that there was no significant difference in S-100β and GFAP levels between the 2 study groups.

CLINICAL TRIAL REGISTRATION

Available at: http://cris.nih.go.kr, KCT0002698.

Glial Fibrillary Acidic Protein Serum Level as a Predictor of Clinical Outcome in Ischemic Stroke

BACKGROUND

Glial Fibrillary Acidic Protein (GFAP) is a protein produced by astrocytes in response to brain injury, which then penetrates the cerebrospinal fluid and the blood stream.

AIM

We sought to determine whether GFAP serum level in acute ischemic stroke could predict clinical outcome.

METHODS

As much as 64 patients with first-ever ischemic stroke had their GFAP serum level measured at 72 hours after onset. The National Institute of Health Stroke Scale (NIHSS) was assessed during the 72 hours of onset, the seventh day, and followed up 1 month after.

RESULTS

There were 46 men and 18 women included in the study. Mean age was 58.3 years old, and nearly half of them (46.9%) were between 50-59 years old. More than half (58.7%) presented with moderate to a severe stroke and mean GFAP serum level was 0.113 ± 0.029 ng/mL. GFAP serum levels had a significant correlation with NIHSS after 1 month (p = 0.04, r = 0.259).

CONCLUSION

There is a significant correlation between GFAP serum levels with stroke severity scale after 1 month of stroke onset.

Neuron-Specific Enolase and Matrix Metalloproteinase 9 Signal Perioperative Silent Brain Infarction During or After Transcatheter Aortic Valve Implantation

Magnetic resonance imaging (MRI) studies have consistently identified a high incidence of silent brain infarction (SBI) after cardiac intervention. The frequent occurrence, objective measurement and clinical sequelae of SBI have seen interest in their detection for both research and clinical purposes. However, MRI is expensive, time-consuming, unsafe in acutely-ill patients, and not always available, limiting its use as a routine screening tool. For this purpose, a blood biomarker of SBI would be the "Holy Grail." By performing targeted profiling of serologic biomarkers this study aimed to assess their potential as screening tools for perioperative SBI. This is a nested case-control study of 20 prospectively recruited patients undergoing transcatheter aortic valve implantation under general anesthesia. Clinical and diffusion-weighted MRI assessments were performed at baseline and on day 3 postprocedure to identify the presence (cases) or absence (controls) of new SBI. Blood was collected at baseline and 24, 48, and 72 hours postprocedure and analyzed for S100 calcium-binding protein B, neuron specific enolase (NSE), matrix metalloproteinase 9 (MMP 9), and glial fibrillary acidic protein. Best-fit polynomial curves using a smoothing model were generated for each biomarker and inferential testing at a predefined 24-hour postprocedure timepoint detected a significant difference for MMP 9 (72,435; SEM: 25,030; p = 0.027). Longitudinal regression revealed a statistically significant case-control difference for both NSE (mean: 10,747; SEM: 3,114) and MMP 9 (63,842; SEM: 16,173). In conclusion, NSE and MMP 9 are present in higher levels following SBI and warrant further investigation for their utility as screening tools.

Coenzyme Q10 supplementation in acute ischemic stroke: Is it beneficial in short-term administration?

Backgrounds and aims: Clinical studies demonstrated that the efficacy of Coenzyme Q10 (CoQ10) as an adjuvant therapeutic agent in several neurological diseases such as Parkinson disease (PD), Huntington disease (HD), and migraine. The purpose of this study is to investigate oxidative stress effects, antioxidant enzymes activity, neuroinflammatory markers levels, and neurological outcome in acute ischemic stroke (AIS) patients following administration of CoQ10 (300 mg/day). Methods: Patients with AIS (n = 60) were randomly assigned to a placebo group (wheat starch, n = 30) or CoQ10-supplemented group (300 mg/day, n = 30). The intervention was administered for 4 weeks. Serum CoQ10 concentration, malondialdehyde (MDA), superoxide dismutase (SOD) activity, glial fibrillary acidic protein (GFAP) levels as primary outcomes and National Institute of Health Stroke Scale (NIHSS), Modified Ranking Scale (MRS), and Mini-Mental State Examination (MMSE) as secondary outcome were measured at the both beginning and end of the study. Results: Forty-four subjects with AIS completed the intervention study. A significant increase in CoQ10 level was observed in the supplement-treated group compared with placebo group (mean difference = 26.05 ± 26.63 ng/ml, 14.12 ± 14.69 ng/ml, respectively; P = 0.01), moreover CoQ10 supplementation improved NIHSS and MMSE scores significantly (P = 0.05, P = 0.03 respectively). but there were no statistically significant differences in MRS score, MDA, SOD, and GFAP levels between the two groups. Conclusions: CoQ10 probably due to low dose and short duration of supplementation, no favorable effects on MDA level, SOD activity and GFAP level.

Serum biomarkers of neuronal injury in newborns evaluated for selective head cooling: a comparative pilot study

Background Evaluation of newborns for hypoxic ischemic encephalopathy (HIE) includes laboratory and clinical parameters, as well as amplitude integrated electroencephalogram (aEEG). Based on qualifying criteria, selective head cooling (SHC) is initiated for infants with evidence of moderate to severe HIE. However, some newborns may not qualify for hypothermia therapy based on normal aEEG. Objective To compare levels of serum glial fibrillary acidic protein (GFAP), ubiquitin c-terminal hydrolase-1 (UCHL-1) protein and phosphorylated axonal neurofilament heavy chain (pNF-H), in newborns who met initial screening criteria for HIE but did not qualify for head cooling, to the levels in healthy newborns. Study design Newborns ≥36 weeks of gestational age at risk for HIE, who were evaluated but did not qualify for SHC from July 2013 through June 2014 at NYU Langone Medical Center and Bellevue Hospital center were enrolled. A control group included healthy newborns from the newborn nursery (NBN). Serum samples were collected between 24 and 48 h of life from both groups. Results There was no significant difference in the serum levels of GFAP, UCHL-1 protein and pNF-H between the two groups of infants. Conclusion Newborns at risk for HIE who met the initial criteria for head cooling but who were excluded based on normal aEEG did not show significant elevation of biomarkers of brain injury compared to healthy newborns. These findings may help to validate using aEEG as an additional evaluation criteria in cooling.

Post-mortem serum concentrations of GFAP correlate with agony time but do not indicate a primary cerebral cause of death

Background and purpose

The astroglial protein GFAP is a blood biomarker indicative of intracerebral hemorrhage in patients with acute stroke. Due to its brain specificity and the necessity of brain damage for its detectability in blood, we hypothesized that GFAP could be an interesting marker in cases with primary cerebral cause of death, e.g., traumatic brain injury.

Methods

All corpses scheduled for an autopsy in the Frankfurt Department of Forensic medicine within a 15-month period were included in the study. Cases with a known history of brain disease in the 3 months before death were excluded. During autopsy, blood was collected and GFAP serum levels were determined using a commercially available ELISA. The autopsy protocols were reviewed for the presence of a primary cerebral or a primary non-cerebral cause of death. Agony time was also determined.

Results

A total of 129 autopsy cases were included. GFAP concentrations did not differ between cerebral (median 0.96 μg/l, IQR 5.03) and non-cerebral causes of death (1.21 μg/l, 3.58). GFAP levels were found to be unaffected by hemolysis or post-mortem interval. GFAP levels were found to be increased in cases with prolonged agony times (median 1.76 μg/l [IQR 4.70]) compared to short (0.58 μg/l [0.58]; p<0.001) and ultra-short agony times (0.21 μg/l [0.12]; p = 0.002).

Conclusion

Post-mortem GFAP serum concentrations correlate with agony time and might therefore be useful for the evaluation of the severity of brain damage in prolonged death. Elevated GFAP serum levels do not indicate a primary cerebral cause of death.

Plasma Unesterified Fatty-Acid Profile Is Dramatically and Acutely Changed under Ischemic Stroke in the Mouse Model

Although plasma biomarkers would facilitate rapid and accurate diagnosis of ischemic stroke for immediate treatment, no such biomarkers have been developed to date. In the present study, we tested our hypothesis that plasma unesterified fatty acids (FFA) are altered at early stages of acute ischemic stroke. Plasma was collected from mice 2 h after the permanent middle cerebral artery occlusion (pMCAo) onset, as well as from sham operated and control animals. After 2 h, pMCAo significantly changed the plasma FFA profile with the most dramatic 2- to 3-fold relative increase in very long n-3 and n-6 FFA including 20:4n-6, 22:4n-6, 22:5n-6, and 22:6n-3. Changes in the plasma FFA profile are consistent with FFA liberation from brain phospholipid hydrolyzed under ischemic insult. These results identify, for the first time, the plasma FFA profile as a potential biomarker for an early ischemic stroke within the therapeutic window for thrombolytic treatment. Further studies are required to confirm its specificity and sensitivity in clinical settings.

Elevated Serum Glial Fibrillary Acidic Protein (GFAP) is Associated with Poor Functional Outcome After Cardiopulmonary Resuscitation

BACKGROUND

The neurological prognosis of patients after cardiopulmonary resuscitation (CPR) is difficult to assess. GFAP is an astrocytic intermediate filament protein released into bloodstream in case of cell death. We performed a prospective study aiming to compare the predictive potential of GFAP after resuscitation to the more widely used biomarker neuron-specific enolase (NSE).

METHODS

One hundred patients were included at 48 h (tolerance interval ±12 h) after cardiac arrest. A serum sample was collected immediately after study inclusion. We determined serum levels of GFAP and NSE by means of immunoassays. Primary outcome was the modified Glasgow outcome scale at 4 weeks. Values below four were considered as a poor functional outcome.

RESULTS

Median GFAP levels in poor outcome (n = 61) and good outcome (n = 39) patients were 0.03 μg/L (interquartile range 0.01-0.07 μg/L) and 0.02 μg/L (0.01-0.03 μg/L; p = 0.014), respectively. GFAP revealed a sensitivity of 60.7% and a specificity of 66.7% to predict a poor functional outcome. All patients having a GFAP level >0.08 µg/L had a poor functional outcome. For NSE, sensitivity was 44.3% and specificity was 100.0% for predicting a poor outcome. Multivariate regression analysis revealed GFAP, NSE, and the Karnofsky index to be independent predictors of outcome.

CONCLUSIONS

The release patterns of GFAP and NSE after CPR show differences. GFAP levels above 0.08 µg/L were associated with a poor outcome in all cases, and patients with strongly elevated values (>3 µg/L) consistently had severe brain damage on brain imaging. Both biomarkers independently contribute to outcome prediction after CPR.

Glial fibrillary acidic protein as a prognostic marker of acute ischemic stroke

Background:

We investigated the association between serum levels of glial fibrillary acidic protein (GFAP) and stroke functional outcomes in a cohort of 286 patients with acute ischemic stroke (AIS).

Methods:

We prospectively studied 286 patients with AIS who were admitted within 24 h after the onset of symptoms. Serum levels of GFAP and National Institutes of Health Stroke Scale (NIHSS) were measured at admission. The primary end point was stroke functional outcome among 1-year after stroke onset. We used logistic regression models to assess the relationship between GFAP levels and stroke outcomes.

Results:

The GFAP level was obtained with a median value of 0.18 (interquartile ranges (IQRs): 0.09–0.28) ng/ml. In multivariable models adjusted for age, gender, and other risk factors, GFAP levels were associated with an increased risk of a NIHSS>6 (odds ratio (OR) = 1.55; 95% confidence interval (CI): 1.16–1.89; p = 0.012). The poor outcome distribution across the GFAP quartiles ranged between 12.7% (first quartile) and 70.4% (fourth quartile). After adjusting for other established risk factors, in multivariate models comparing the Q3 and Q 4 quartiles against the Q1 of the GFAP, the levels of GFAP were associated with poor outcome, and the adjusted risk of poor outcome increased by 211% (3.11[1.80–5.05], p < 0.001) and 522% (6.22[2.98–11.83], p < 0.001), respectively. Interestingly, GFAP improved the ability of NIHSS score to diagnose poor outcomes (area under the curve [AUC] of the combined model 0.82; 95% CI: 0.77–0.88; p = 0.02).

Conclusion:

GFAP levels are a novel and complementary biomarker to predict functional outcome 1 year after AIS

RNA-Seq Identifies Circulating miR-125a-5p, miR-125b-5p, and miR-143-3p as Potential Biomarkers for Acute Ischemic Stroke

RATIONALE

Currently, there are no blood-based biomarkers with clinical utility for acute ischemic stroke (IS). MicroRNAs show promise as disease markers because of their cell type-specific expression patterns and stability in peripheral blood.

OBJECTIVE

To identify circulating microRNAs associated with acute IS, determine their temporal course up to 90 days post-stroke, and explore their utility as an early diagnostic marker.

METHODS AND RESULTS

We used RNA sequencing to study expression changes of circulating microRNAs in a discovery sample of 20 patients with IS and 20 matched healthy control subjects. We further applied quantitative real-time polymerase chain reaction in independent samples for validation (40 patients with IS and 40 matched controls), replication (200 patients with IS, 100 healthy control subjects), and in 72 patients with transient ischemic attacks. Sampling of patient plasma was done immediately upon hospital arrival. We identified, validated, and replicated 3 differentially expressed microRNAs, which were upregulated in patients with IS compared with both healthy control subjects (miR-125a-5p [1.8-fold; P=1.5×10^-6], miR-125b-5p [2.5-fold; P=5.6×10^-6], and miR-143-3p [4.8-fold; P=7.8×10^-9]) and patients with transient ischemic attack (miR-125a-5p: P=0.003; miR-125b-5p: P=0.003; miR-143-3p: P=0.005). Longitudinal analysis of expression levels up to 90 days after stroke revealed a normalization to control levels for miR-125b-5p and miR-143-3p starting at day 2 while miR-125a-5p remained elevated. Levels of all 3 microRNAs depended on platelet numbers in a platelet spike-in experiment but were unaffected by chemical hypoxia in Neuro2a cells and in experimental stroke models. In a random forest classification, miR-125a-5p, miR-125b-5p, and miR-143-3p differentiated between healthy control subjects and patients with IS with an area under the curve of 0.90 (sensitivity: 85.6%; specificity: 76.3%), which was superior to multimodal cranial computed tomography obtained for routine diagnostics (sensitivity: 72.5%) and previously reported biomarkers of acute IS (neuron-specific enolase: area under the curve=0.69; interleukin 6: area under the curve=0.82).

CONCLUSIONS

A set of circulating microRNAs (miR-125a-5p, miR-125b-5p, and miR-143-3p) associates with acute IS and might have clinical utility as an early diagnostic marker.

Effects of hypothermia on S100B and glial fibrillary acidic protein in asphyxia rats after cardiopulmonary resuscitation

The aim of the study was to investigate the effects of hypothermia on S100B and glial fibrillary acidic protein (GFAP) in serum and hippocampus CA1 area in asphyxiated rats after cardiopulmonary resuscitation (CPR). A total of 100 SD rats were designated into four groups: group A, sham operation group; group B, rats received conventional resuscitation; group C, rats received conventional resuscitation and hypothermia at cardiac arrest; group D, rats received conventional resuscitation and hypothermia at 30 min after restoration of spontaneous circulation (ROSC). Rats were then killed by cardiac arrest at 2 and 4 h after ROSC; brain tissue was taken to observe dynamic changes of S100B and GFAP in serum and hippocampus CA1 area. Following ROSC, S100B levels increased from 2 to 4 h in group B, C, and D. In addition, S100B in serum and hippocampus CA1 area was all significantly increased at different time points compared with group A (P < 0.05). Following ROSC, serum S100B level at 2 h in group C was significantly decreased compared with group B, but the difference was not statistically significant (P > 0.05). Moreover, S100B in serum at 4 h after ROSC was significantly decreased (P < 0.05), S100B in cortex was significantly decreased (P < 0.05). The expression of GFAP was also examined. GFAP level in hippocampus CA1 area was significantly decreased in group B, C, and D at 4 h after ROSC compared with group A (P < 0.05). S100B and GFAP were expressed in rat serum and hippocampus CA2 area at early stage after ROSC, which can be used as sensitive markers for brain injury diagnosis and prognosis prediction. Hypothermia is also shown to reduce brain injury after CPR.

Evidence of an association between brain cellular injury and cognitive decline after non-cardiac surgery

BACKGROUND

Postoperative cognitive dysfunction (POCD) is common after non-cardiac surgery, but the mechanism is unclear. We hypothesized that decrements in cognition 1 month after non-cardiac surgery would be associated with evidence of brain injury detected by elevation of plasma concentrations of S100β, neuron-specific enolase (NSE), and/or the brain-specific protein glial fibrillary acid protein (GFAP).

METHODS

One hundred and forty-nine patients undergoing shoulder surgery underwent neuropsychological testing before and then 1 month after surgery. Plasma was collected before and after anaesthesia. We determined the relationship between plasma biomarker concentrations and individual neuropsychological test results and a composite cognitive functioning score (mean Z-score).

RESULTS

POCD (≥-1.5 sd decrement in Z-score from baseline) was present in 10.1% of patients 1 month after surgery. There was a negative relationship between higher plasma GFAP concentrations and lower postoperative composite Z-scores {estimated slope=-0.14 [95% confidence interval (CI) -0.24 to -0.04], P=0.005} and change from baseline in postoperative scores on the Rey Complex Figure Test copy trial (P=0.021), delayed recall trial (P=0.010), and the Symbol Digit Modalities Test (P=0.004) after adjustment for age, sex, history of hypertension and diabetes. A similar relationship was not observed with S100β or NSE concentrations.

CONCLUSIONS

Decline in cognition 1 month after shoulder surgery is associated with brain cellular injury as demonstrated by elevated plasma GFAP concentrations.

The use of serum glial fibrillary acidic protein test as a promising tool for intracerebral hemorrhage diagnosis in Chinese patients and prediction of the short-term functional outcomes

The objective of this study was to explore the efficacy of glial fibrillary acidic protein (GFAP) in differentiating intracerebral hemorrhage (ICH) from ischemic stroke (IS). Suspicious patients of acute stroke were screened and finally diagnosed by computed tomography and magnetic resonance imaging. Blood samples were collected within 2-6 h after onset of symptoms, and serum GFAP level was determined by ELISA assay. The functional outcome for the patients was determined by modified Rankin Scale (mRS) 90 days after onset of symptoms. 43 ICH patients and 65 IS patients were enrolled. GFAP concentration in ICH group was significantly higher than in IS group (p < 0.001). Significant correlation was found when comparing GFAP with National Institutes of Health Stroke Scale (NIHSS) (r = 0.418, p = 0.005) and hemorrhage volume (r = 0.840, p < 0.001) in ICH group, while such correlation was not observed in IS group. ROC analysis indicated that GFAP level at the cut-point of 0.7 ng/ml yielded an AUC of 0.901 (95 % CI 0.828-0.950) with high sensitivity (86.0 %) and specificity (76.9 %) to differentiate ICH from IS. Patients with higher serum GFAP concentration in ICH group experienced poorer functional disability (r = 0.755, p < 0.001), while this phenomenon was not observed in IS group (r = -0.114, p = 0.368). ROC curve analysis found that GFAP level at the cut-point of 1.04 ng/ml yielded an AUC of 0.936 (95 % CI 0.817-0.988) in identifying patients with poor functional outcome, at the sensitivity and specificity of 95.7 and 80.0 %, respectively. GFAP test is a promising technique for diagnosis of ICH from IS and prediction of short-term functional outcomes.

Hypotension After Cardiac Operations Based on Autoregulation Monitoring Leads to Brain Cellular Injury

BACKGROUND

Individualizing blood pressure targets could improve organ perfusion compared with current practices. In this study we assess whether hypotension defined by cerebral autoregulation monitoring vs standard definitions is associated with elevation in the brain-specific injury biomarker glial fibrillary acidic protein plasma levels (GFAP).

METHODS

Plasma GFAP levels were measured in 121 patients undergoing cardiac operations after anesthesia induction, at the conclusion of the operation, and on postoperative day 1. Cerebral autoregulation was monitored during the operation with the cerebral oximetry index, which correlates low-frequency changes in mean arterial pressure (MAP) and regional cerebral oxygen saturation. Blood pressure was recorded every 15 minutes in the intensive care unit. Hypotension was defined based on autoregulation data as an MAP below the optimal MAP (MAP at the lowest cerebral oximetry index) and based on standard definitions (systolic blood pressure decrement >20%, >30% from baseline, or <100 mm Hg, or both).

RESULTS

MAP (mean ± standard deviation) in the intensive care unit was 74 ± 7.3 mm Hg; optimal MAP was 78 ± 12.8 mm Hg (p = 0.008). The incidence of hypotension varied from 22% to 37% based on standard definitions but occurred in 54% of patients based on the cerebral oximetry index (p < 0.001). There was no relationship between standard definitions of hypotension and plasma GFAP levels, but MAP of less than optimal was positively related with postoperative day 1 GFAP levels (coefficient, 1.77; 95% confidence interval, 1.27 to 2.48; p = 0.001) after adjusting for GFAP levels at the conclusion of the operation and low cardiac output syndrome.

CONCLUSIONS

Individualizing blood pressure management using cerebral autoregulation monitoring may better ensure brain perfusion than current practice.

Targeted Lipid Profiling Discovers Plasma Biomarkers of Acute Brain Injury

Prior efforts to identify a blood biomarker of brain injury have relied almost exclusively on proteins; however their low levels at early time points and poor correlation with injury severity have been limiting. Lipids, on the other hand, are the most abundant molecules in the brain and readily cross the blood-brain barrier. We previously showed that certain sphingolipid (SL) species are highly specific to the brain. Here we examined the feasibility of using SLs as biomarkers for acute brain injury. A rat model of traumatic brain injury (TBI) and a mouse model of stroke were used to identify candidate SL species though our mass-spectrometry based lipid profiling approach. Plasma samples collected after TBI in the rat showed large increases in many circulating SLs following injury, and larger lesions produced proportionately larger increases. Plasma samples collected 24 hours after stroke in mice similarly revealed a large increase in many SLs. We constructed an SL score (sum of the two SL species showing the largest relative increases in the mouse stroke model) and then evaluated the diagnostic value of this score on a small sample of patients (n = 14) who presented with acute stroke symptoms. Patients with true stroke had significantly higher SL scores than patients found to have non-stroke causes of their symptoms. The SL score correlated with the volume of ischemic brain tissue. These results demonstrate the feasibility of using lipid biomarkers to diagnose brain injury. Future studies will be needed to further characterize the diagnostic utility of this approach and to transition to an assay method applicable to clinical settings.

Glial fibrillary acidic protein: from intermediate filament assembly and gliosis to neurobiomarker

Glial fibrillary acidic protein (GFAP) is an intermediate filament (IF) III protein uniquely found in astrocytes in the central nervous system (CNS), non-myelinating Schwann cells in the peripheral nervous system (PNS), and enteric glial cells. GFAP mRNA expression is regulated by several nuclear-receptor hormones, growth factors, and lipopolysaccharides (LPSs). GFAP is also subject to numerous post-translational modifications (PTMs), while GFAP mutations result in protein deposits known as Rosenthal fibers in Alexander disease. GFAP gene activation and protein induction appear to play a critical role in astroglial cell activation (astrogliosis) following CNS injuries and neurodegeneration. Emerging evidence also suggests that, following traumatic brain and spinal cord injuries and stroke, GFAP and its breakdown products are rapidly released into biofluids, making them strong candidate biomarkers for such neurological disorders.

[Glial fibrillary acidic protein in patients with symptoms of acute stroke: diagnostic marker of cerebral hemorrhage]

Glial fibrillary acidic protein (GFAP) is a highly brain-specific protein that is expressed in large quantities in astrocytes and has important functions in terms of maintaining and stabilizing the cytoskeleton. Acute intracerebral hemorrhage leads to an immediate mechanical destruction of astroglial cells with the subsequent release of GFAP into the extracellular space and the bloodstream. On the other hand, necrosis, cytolysis and GFAP release does not occur before 6-12 h after symptom onset in ischemic stroke. Thus, in the early hours after stroke increased GFAP values could indicate intracerebral hemorrhage. This review article describes the underlying pathophysiology of the test and guides the reader through the available data. Potential implications regarding the prehospital triage of acute stroke patients are discussed, including the possibility to initiate hyperacute treatment, such as blood pressure reduction in patients with intracerebral hemorrhage. Other areas of interest for a potential GFAP test include traumatic brain injury and malignant gliomas.

Glial fibrillary acidic protein in children with congenital heart disease undergoing cardiopulmonary bypass

OBJECTIVE

To determine whether blood levels of the brain-specific biomarker glial fibrillary acidic protein rise during cardiopulmonary bypass for repair of congenital heart disease.

METHODS

This is a prospective observational pilot study to characterise the blood levels of glial fibrillary acidic protein during bypass. Children <21 years of age undergoing bypass for congenital heart disease at Johns Hopkins Hospital and Texas Children's Hospital were enrolled. Blood samples were collected during four phases: pre-bypass, cooling, re-warming, and post-bypass.

RESULTS

A total of 85 patients were enrolled between October, 2010 and May, 2011. The median age was 0.73 years (range 0.01-17). The median weight was 7.14 kilograms (range 2.2-86.5). Single ventricle anatomy was present in 18 patients (22%). Median glial fibrillary acidic protein values by phase were: pre-bypass: 0 ng/ml (range 0-0.35); cooling: 0.039 (0-0.68); re-warming: 0.165 (0-2.29); and post-bypass: 0.112 (0-0.97). There were significant elevations from pre-bypass to all subsequent stages, with the greatest increase during re-warming (p = 0.0001). Maximal levels were significantly related to younger age (p = 0.03), bypass time (p = 0.03), cross-clamp time (p = 0.047), and temperature nadir (0.04). Peak levels did not vary significantly in those with single ventricle anatomy versus two ventricle repairs.

CONCLUSION

There are significant increases in glial fibrillary acidic protein levels in children undergoing cardiopulmonary bypass for repair of congenital heart disease. The highest values were seen during the re-warming phase. Elevations are significantly associated with younger age, bypass and cross-clamp times, and temperature nadir. Owing to the fact that glial fibrillary acidic protein is the most brain-specific biomarker identified to date, it may act as a rapid diagnostic marker of brain injury during cardiac surgery.

Serum glial fibrillary acidic protein as a biomarker for differentiating intracerebral hemorrhage and ischemic stroke in patients with symptoms of acute stroke: a systematic review and meta-analysis

Serum glial fibrillary acidic protein (GFAP) has been reported to have high diagnosis accuracy for differentiating intracerebral hemorrhage (ICH) from ischemic stroke (IS) in patients within acute phase of stroke symptom onset. Our purpose was to perform a systematic review and diagnostic meta-analysis to evaluate the valuation of serum GFAP in the early identification of ICH and IS. We searched MEDLINE, EMBASE and other electronic databases for diagnostic accuracy studies that compared serum GFAP with standard clinical diagnosis of ICH and IS in patients with symptoms of acute stroke. All publication years were included through to April 2013. The sensitivity (SEN), specificity (SPE), and positive and negative likelihood ratios (PLR and NLR, respectively) of serum GFAP for differentiating ICH and IS were pooled using a bivariate meta-analysis. Summary receiver operating characteristic curves were used to summarize overall test performance. A total of five trials met our inclusion criteria. The summarized estimates of serum GFAP for the differentiation of ICH and IS within 24 h of symptom onset were as follows: SEN, 81.1% (95% CI, 72.6-87.5%); SPE, 95.2% (95% CI 82.1-98.9%); PLR, 16.945 (95% CI 4.173-68.803); NLR, 0.198 (95% CI 0.133-0.296), significant heterogeneity was present. The four summary estimates of serum GFAP for patients within 1-6 h of symptom onset were 81.1% (95% CI 72.5-88.0%), 97.0% (95% CI 94.3-98.4%), 26.786 (95% CI 13.979-51.324), 0.191 (95% CI 0.126-0.291), respectively, with no obvious heterogeneity. Serum GFAP is a sensitive and specific test for differentiating ICH and IS in patients within 1-6 h of acute stroke symptom onset.

Serum glial fibrillary acidic protein as a specific marker for necrotizing meningoencephalitis in Pug dogs

To evaluate the ability of serum glial fibrillary acidic protein (GFAP) concentration as a diagnostic marker for canine central nervous system (CNS) disorders, sera from dogs with various CNS (n=47) and non-CNS (n=56) disorders were measured for GFAP by using an ELISA kit. Healthy Beagles (n=15) and Pug dogs (n=12) were also examined as controls. Interestingly, only Pug dogs with necrotizing meningoencephalitis (NME) showed elevated serum GFAP concentrations (<0.01 to 1.14 ng/ml), while other breeds of dogs with NME did not. Among the Pug dogs with NME, serum GFAP concentrations did not correlate with their clinical features, such as ages or survival times. Our data indicate the usefulness of serum GFAP as a novel marker for Pug dogs with NME.

Glial fibrillary acidic protein as a biomarker for periventricular white matter injury

OBJECTIVE

Periventricular white matter injury (PWMI), a precursor of cerebral palsy, traditionally is not diagnosed until 6 weeks of life by head ultrasound scanning. We sought to determine whether early neonatal glial fibrillary acidic protein (GFAP) levels could identify PWMI in low birthweight (<2500 g) infants.

STUDY DESIGN

Each case with PWMI on head ultrasound scanning at 6 weeks of life from April 2009 to April 2011 was matched by gestational age and mode of delivery to 2 subsequent neonates with a normal head ultrasound scan. GFAP was measured in cord blood at birth, at neonatal intensive care unit admission, and on days 1-4 of life.

RESULTS

During this 2-year period, 21 cases with PWMI with gestational age 27.4 ± 3.3 weeks were compared with 42 control infants. The incidence of cesarean delivery was 61.9% in both groups. GFAP was not significantly different in cord blood or at neonatal intensive care unit admission but was significantly elevated on day 1 (median, 5-95%; 0, 0-0.98 ng/mL cases; 0, 0-0.06 ng/mL control infants; P = .03), day 2 (0, 0-1.21 ng/mL; 0, 0-0.05 ng/mL, respectively; P = .02), day 3 (0.05, 0-0.33 ng/mL; 0, 0-0.04 ng/mL, respectively; P = .004), and day 4 (0.02, 0-1.03 ng/mL; 0, 0-0.05 ng/mL, respectively; P < .001). The odds of the development of PWMI significantly increased with increasing levels of GFAP from day 1-4 of life when adjustment was made for preeclampsia, antenatal steroid administration, and neonatal chronic lung disease.

CONCLUSION

The ability to predict PWMI with a blood test for GFAP shortly after birth opens the possibility for rapid identification of infants for early intervention and provides a benchmark for the qualification of new therapies to improve neurodevelopmental outcomes.