Serum glial fibrillary acidic protein as a biomarker for intracerebral haemorrhage in patients with acute stroke

Serum and cerebrospinal fluid neurofilament light chain and glial fibrillary acid protein levels in early and advanced stages of cerebral amyloid Angiopathy

BACKGROUND

Neurofilament light chain (NFL) is a biomarker for neuroaxonal damage and glial fibrillary acidic protein (GFAP) for reactive astrocytosis. Both processes occur in cerebral amyloid angiopathy (CAA), but studies investigating the potential of NFL and GFAP as markers for CAA are lacking. We aimed to investigate NFL and GFAP as biomarkers for neuroaxonal damage and astrocytosis in CAA.

METHODS

For this cross-sectional study serum and cerebrospinal fluid (CSF) samples were collected between 2010 and 2020 from controls, (pre)symptomatic Dutch-type hereditary (D-CAA) mutation-carriers and participants with sporadic CAA (sCAA) from two prospective CAA studies at two University hospitals in the Netherlands. NFL and GFAP levels were measured with Simoa-assays. The association between NFL and GFAP levels and age, cognitive performance (MoCA), CAA-related MRI markers (CAA-CSVD-burden) and Aβ40 and Aβ42 levels in CSF were assessed with linear regression adjusted for confounders. The control group was divided in age < 55 and ≥55 years to match the specific groups.

RESULTS

We included 187 participants: 28 presymptomatic D-CAA mutation-carriers (mean age 40 years), 29 symptomatic D-CAA participants (mean age 58 years), 59 sCAA participants (mean age 72 years), 33 controls < 55 years (mean age 42 years) and 38 controls ≥ 55 years (mean age 65 years). In presymptomatic D-CAA, only GFAP in CSF (7.7*103pg/mL vs. 4.4*103pg/mL in controls; P<.001) was increased compared to controls. In symptomatic D-CAA, both serum (NFL:26.2pg/mL vs. 12.5pg/mL; P=0.008, GFAP:130.8pg/mL vs. 123.4pg/mL; P=0.027) and CSF (NFL:16.8*102pg/mL vs. 7.8*102pg/mL; P=0.01 and GFAP:11.4*103pg/mL vs. 7.5*103pg/mL; P<.001) levels were higher than in controls and serum levels (NFL:26.2pg/mL vs. 6.7pg/mL; P=0.05 and GFAP:130.8pg/mL vs. 66.0pg/mL; P=0.004) were higher than in pre-symptomatic D-CAA. In sCAA, only NFL levels were increased compared to controls in both serum (25.6pg/mL vs. 12.5pg/mL; P=0.005) and CSF (20.0*102pg/mL vs 7.8*102pg/mL; P=0.008). All levels correlated with age. Serum NFL correlated with MoCA (P=0.008) and CAA-CSVD score (P<.001). NFL and GFAP in CSF correlated with Aβ42 levels (P=0.01/0.02).

CONCLUSIONS

GFAP level in CSF is an early biomarker for CAA and is increased years before symptom onset. NFL and GFAP levels in serum and CSF are biomarkers for advanced CAA.

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.

Molecular mechanisms of ischemia and glutamate excitotoxicity

Excitotoxicity is classically defined as the neuronal damage caused by the excessive release of glutamate, and subsequent activation of excitatory plasma membrane receptors. In the mammalian brain, this phenomenon is mainly driven by excessive activation of glutamate receptors (GRs). Excitotoxicity is common to several chronic disorders of the Central Nervous System (CNS) and is considered the primary mechanism of neuronal loss of function and cell death in acute CNS diseases (e.g. ischemic stroke). Multiple mechanisms and pathways lead to excitotoxic cell damage including pro-death signaling cascade events downstream of glutamate receptors, calcium (Ca2+) overload, oxidative stress, mitochondrial impairment, excessive glutamate in the synaptic cleft as well as altered energy metabolism. Here, we review the current knowledge on the molecular mechanisms that underlie excitotoxicity, emphasizing the role of Nicotinamide Adenine Dinucleotide (NAD) metabolism. We also discuss novel and promising therapeutic strategies to treat excitotoxicity, highlighting recent clinical trials. Finally, we will shed light on the ongoing search for stroke biomarkers, an exciting and promising field of research, which may improve stroke diagnosis, prognosis and allow better treatment options.

Unlocking the Potential of Stroke Blood Biomarkers: Early Diagnosis, Ischemic vs. Haemorrhagic Differentiation and Haemorrhagic Transformation Risk: A Comprehensive Review

Stroke, a complex and heterogeneous disease, is a leading cause of morbidity and mortality worldwide. The timely therapeutic intervention significantly impacts patient outcomes, but early stroke diagnosis is challenging due to the lack of specific diagnostic biomarkers. This review critically examines the literature for potential biomarkers that may aid in early diagnosis, differentiation between ischemic and hemorrhagic stroke, and prediction of hemorrhagic transformation in ischemic stroke. After a thorough analysis, four promising biomarkers were identified: Antithrombin III (ATIII), fibrinogen, and ischemia-modified albumin (IMA) for diagnostic purposes; glial fibrillary acidic protein (GFAP), micro RNA 124-3p, and a panel of 11 metabolites for distinguishing between ischemic and hemorrhagic stroke; and matrix metalloproteinase-9 (MMP-9), s100b, and interleukin 33 for predicting hemorrhagic transformation. We propose a biomarker panel integrating these markers, each reflecting different pathophysiological stages of stroke, that could significantly improve stroke patients' early detection and treatment. Despite promising results, further research and validation are needed to demonstrate the clinical utility of this proposed panel for routine stroke treatment.

Serum Urea-to-Albumin Ratio Is an Independent Predictor of Intra-Hospital Mortality in Neurosurgical Intensive Care Unit Patients with Spontaneous Intracerebral Hemorrhage

The negative prognostic value of an increased serum urea-to-albumin ratio on intra-hospital mortality is frequently investigated in general critically ill patients and patients with septic shock, although not in neurosurgical patients with spontaneous intracerebral hemorrhages (ICH). The current study was conducted to investigate the impact of the serum urea-to-albumin ratio upon hospital admission on intra-hospital mortality in ICU-admitted neurosurgical patients with spontaneous ICH.

METHODS

This retrospective study analyzed 354 ICH patients, who were treated from 10/2008 to 12/2017 at our intensive care units (ICU). Blood samples were taken upon admission, and the patients' demographic, medical, and radiological data were analyzed. A binary logistic regression analysis was performed for the identification of independent prognostic parameters for intra-hospital mortality.

RESULTS

Overall, the intra-hospital mortality rate was 31.4% (n = 111). In the binary logistic analysis, a higher serum urea-to-albumin ratio (OR = 1.9, CI = 1.23-3.04, p = 0.005) upon admission was identified as an independent predictor of intra-hospital mortality. Furthermore, a serum urea-to-albumin ratio cut-off level of >0.01 was associated with raised intra-hospital mortality (Youden's index = 0.32, sensitivity = 0.57, specificity = 0.25).

CONCLUSION

A serum urea-to-albumin ratio greater than 1.1 seems to be a prognostic marker to predict intra-hospital mortality in patients with ICH.

Serum Neurofilament Light Chain and Glial Fibrillary Acidic Protein as Potential Diagnostic Biomarkers in Autism Spectrum Disorders: A Preliminary Study

Autism spectrum disorder (ASD) is one of the most common neurodevelopment disorders, characterized by a multifactorial etiology based on the interaction of genetic and environmental factors. Recent evidence supports the neurobiological hypothesis based on neuroinflammation theory. To date, there are no sufficiently validated diagnostic and prognostic biomarkers for ASD. Therefore, we decided to investigate the potential diagnostic role for ASD of two biomarkers well known for other neurological inflammatory conditions: the glial fibrillary acidic protein (GFAP) and the neurofilament (Nfl). Nfl and GFAP serum levels were analyzed using SiMoA technology in a group of ASD patients and in a healthy control group (CTRS), age- and gender-matched. Then we investigated the distribution, frequency, and correlation between serum Nfl and GFAP levels and clinical data among the ASD group. The comparison of Nfl and GFAP serum levels between ASD children and the control group showed a mean value of these two markers significantly higher in the ASD group (sNfL mean value ASD pt 6.86 pg/mL median value ASD pt 5.7 pg/mL; mean value CTRS 3.55 pg/mL; median value CTRS 3.1 pg; GFAP mean value ASD pt 205.7 pg/mL median value ASD pt 155.4 pg/mL; mean value CTRS 77.12 pg/mL; median value CTRS 63.94 pg/mL). Interestingly, we also found a statistically significant positive correlation between GFAP levels and hyperactivity symptoms (p-value <0.001). Further investigations using larger groups are necessary to confirm our data and to verify in more depth the potential correlation between these biomarkers and ASD clinical features, such as the severity of the core symptoms, the presence of associated symptoms, and/or the evaluation of a therapeutic intervention. However, these data not only might shed a light on the neurobiology of ASD, supporting the neuroinflammation and neurodegeneration hypothesis, but they also might support the use of these biomarkers in the early diagnosis of ASD, to longitudinally monitor the disease activity, and even more as future prognostic biomarkers.

Serum glial fibrillary acidic protein is sensitive to acute but not chronic tissue damage in cerebral small vessel disease

BACKGROUND

Serum glial fibrillary acidic protein (sGFAP) has been proposed as a biomarker in various neurological diseases but has not yet been systematically investigated in patients with cerebral small vessel disease (CSVD). We explored whether sGFAP levels are increased in stroke patients with MRI-confirmed recent small subcortical infarcts (RSSI) and analyzed the subsequent course and determinants of sGFAP longitudinally.

METHODS

In a prospectively-collected cohort of stroke patients with a single RSSI (n = 101, mean age: 61 years, 73% men), we analyzed brain MRI and sGFAP using a SIMOA assay at baseline and at 3- and 15-months post-stroke. Community-dwelling age- and sex-matched individuals (n = 51) served as controls.

RESULTS

RSSI patients had higher baseline sGFAP levels compared to controls (median: 187.4 vs. 118.3 pg/ml, p < 0.001), with no influence of the time from stroke symptom onset to baseline blood sampling (median 5 days, range 1-13). At the 3- and 15-months follow-up, sGFAP returned to control levels. While baseline sGFAP correlated with larger infarct size (r_s = 0.28, p = 0.01), neither baseline nor follow-up sGFAP levels were associated with chronic CSVD-related lesions (white matter hyperintensities, lacunes, microbleeds) after adjusting for age, sex and hypertension. Furthermore, sGFAP levels did not relate to the occurrence of new vascular brain lesions on follow-up MRI.

CONCLUSIONS

sGFAP is increased in patients with CSVD-related stroke and correlates with the size of the RSSI. However, sGFAP levels were not related to chronic neuroimaging features or progression of CSVD, suggesting that sGFAP is sensitive to acute but not chronic cerebrovascular tissue changes in this condition.

Serum S-100B adds incremental value for the prediction of symptomatic intracranial hemorrhage and brain edema after acute ischemic stroke

Background:

Early identification of patients developing symptomatic intracranial hemorrhage and symptomatic brain edema after acute ischemic stroke is essential for clinical decision-making. Astroglial protein S-100B is a marker of blood-brain barrier disruption, which plays an important role in the formation of intracranial hemorrhage and brain edema. In this study, we assessed the prognostic value of serum S-100B for the development of these complications.

Methods:

Serum S-100B levels were measured within 24 h from symptom onset in 1749 consecutive acute ischemic stroke patients from the prospective, observational, multicenter BIOSIGNAL cohort study (mean age 72.0 years, 58.3% male). To determine symptomatic intracranial hemorrhage or symptomatic brain edema, follow-up neuroimaging was performed in all patients receiving reperfusion therapy or experiencing clinical worsening with an NIHSS increase of ⩾4.

Results:

Forty six patients (2.6%) developed symptomatic intracranial hemorrhage and 90 patients (5.2%) developed symptomatic brain edema. After adjustment for established risk factors, log10S-100B levels remained independently associated with both symptomatic intracranial hemorrhage (OR 3.41, 95% CI 1.7–6.9, p = 0.001) and symptomatic brain edema (OR 4.08, 95% CI 2.3–7.1, p < 0.001) in multivariable logistic regression models. Adding S-100B to the clinical prediction model increased the AUC from 0.72 to 0.75 ( p = 0.001) for symptomatic intracranial hemorrhage and from 0.78 to 0.81 ( p < 0.0001) for symptomatic brain edema.

Conclusions:

Serum S-100B levels measured within 24 h after symptom onset are independently associated with the development of symptomatic intracranial hemorrhage and symptomatic brain edema in acute ischemic stroke patients. Thus, S-100B may be useful for early risk-stratification regarding stroke complications.

Serum Lactate as Serum Biomarker for Cardiopulmonary Parameters within the First 24 Hours after a Spontaneous Intracerebral Hemorrhage

Objective: Cardiopulmonary (CP) complications are well known in patients with an intracerebral hemorrhage (ICH) and could be associated with a higher serum lactate level. The present study aimed to assess the associations between the initial serum lactate level and the CP parameters within the first 24 h of intensive care unit (ICU) treatment in neurosurgical ICH patients. Patients and Methods: A total of 354 patients admitted to the ICU between 01/2009 and 12/2017 with a diagnosis of an ICH were retrospectively analyzed. Blood samples were taken upon admission, and each patient’s demographic, medical, and radiological data upon admission, as well as several CP parameters, were recorded within the first 24 h of ICU treatment. Results: A higher serum lactate level was associated with a lower GCS score (p < 0.0001), as well as a higher Acute Physiology and Chronic Health Evaluation II score (p = 0.002) upon admission. Additionally, patients with initially higher serum lactate levels had a significantly higher need for a norepinephrine application (p = 0.004) and inspiratory oxygen fraction (p = 0.03) within the first 24 h. Conclusion: Neurosurgical ICH patients with higher serum lactate levels upon admission require more CP support within the first 24 h of ICU treatment.

Fibrinogen to Albumin Ratio as Early Serum Biomarker for Prediction of Intra-Hospital Mortality in Neurosurgical Intensive Care Unit Patients with Spontaneous Intracerebral Hemorrhage

Background: The prognostic value of the fibrinogen to albumin ratio on intrahospital mortality has been investigated in patients with cardiovascular disease, cancer, sepsis, and ischemic stroke; however, it has not been investigated for neurosurgical patients with spontaneous intracerebral hemorrhage (ICH). The present study investigates the impact of the fibrinogen to albumin ratio upon admission for intrahospital mortality in neurosurgical intensive care unit (ICU) patients with spontaneous ICH. Methods: A total of 198 patients with diagnosis of spontaneous ICH treated from 10/2008 to 12/2017 at our ICU were retrospectively analyzed. Blood samples were drawn upon admission, and the patients’ demographic, medical data, and cranial imaging were collected. Binary logistic regression analysis was performed to identify independent prognostic factors for intrahospital mortality. Results: The total rate of intrahospital mortality was 35.4% (n = 70). In the multivariate regression analysis, higher fibrinogen to albumin ratio (OR = 1.16, CI = 1.02−1.31, p = 0.03) upon admission was an independent predictor of intrahospital mortality in neurosurgical ICU patients with ICH. Moreover, a fibrinogen to albumin ratio cut-off level of >0.075 was related to increased intrahospital mortality (Youden’s index = 0.26, sensitivity = 0.51, specificity = 0.77). Conclusion: A fibrinogen to albumin ratio > 0.075 was significantly associated with increased intrahospital mortality in ICH patients.

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.

Association of Changed Serum Brain Biomarkers With Perihematomal Edema and Early Clinical Outcome in Primary ICH Patients

BACKGROUND

Perihematomal edema (PHE) following primary intracranial hemorrhages (ICHs) affects the patient outcome. Also, serum biomarkers such as S100 calcium-binding protein B (S100B) and glial fibrillary acidic protein (GFAP) have been associated with ICHs outcome. We aimed to investigate the association between these biomarkers and PHE in ICH patients.

METHODS

In this cross-sectional study, patients with primary ICH between January 2020 and August 2020 were evaluated. All participants underwent spiral brain computed tomography scans upon admission, and 48 to 72 hours later and quantification of initial hematoma volume was performed. Serum level of matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor (VEGF), GFAP, and S100B on admission were measured by enzyme-linked immunosorbent assays. Acute clinical outcome was assessed by the modified-Rankin scale, National Institute of Health Stroke Scale (NIHSS), and ICH score.

RESULTS

Thirty-seven ICH patients (21 patients with a favorable outcome and 16 unfavorable) were studied. Compared with survival patients, nonsurvivor patients showed a higher serum level of MMP-9, VEGF, GFAP, and S100B ( P <0.05). Scores of absolute PHE, edema expansion distance, and PHE growth rate in the nonsurvivor group were higher than the survivors ( P <0.001). The regression model revealed that MMP-9, VEGF, ICH score, and hematoma volume were associated with the PHE growth rate. S100B and ICH score were associated with edema expansion distance.

CONCLUSIONS

Our data showed that the serum level of molecular biomarkers was associated with higher PHE volume and PHE scores were higher in nonsurvival patients, suggesting it may have a pathogenic role in developing PHE after ICH.

Detection, Diagnosis and Treatment of Acute Ischemic Stroke: Current and Future Perspectives

Stroke is one of the leading causes of disability worldwide. Early diagnosis and treatment of stroke are important for better clinical outcome. Rapid and accurate diagnosis of stroke subtypes is critical. This review discusses the advantages and disadvantages of the current diagnostic and assessment techniques used in clinical practice, particularly for diagnosing acute ischemic stroke. Alternative techniques for rapid detection of stroke utilizing blood based biomarkers and novel portable devices employing imaging methods such as volumetric impedance phase-shift spectroscopy, microwave tomography and Doppler ultrasound are also discussed. Current therapeutic approaches for treating acute ischemic stroke using thrombolytic drugs and endovascular thrombectomy are discussed, with a focus on devices and approaches recently developed to treat large cranial vessel occlusions.

A magnetoimpedance biosensor microfluidic platform for detection of glial fibrillary acidic protein in blood for acute stroke classification

Acute stroke is the third leading cause of mortality and disability worldwide. Administration of appropriate therapy for acute stroke is critically dependent on timely classification into either ischemic or hemorrhagic subtypes, which have divergent treatment pathways. The current classification method is based on neuroimaging, which generally requires the transport of the patient to a hospital-based facility unless a mobile stroke unit is available. Plasma glial fibrillary acidic protein (GFAP) level has been identified as a useful blood-based biomarker to differentiate stroke subtypes. However, its conventional immunoassay methods are laboratory-based and time-consuming. Novel approaches for rapid stroke classification near the patients are urgently needed. Here, we report the development and testing of a microfluidic-based magnetoimpedance biosensor platform for measuring GFAP levels. The platform consists of a microfluidic chip for GFAP extraction from a blood sample and a magnetoimpedance (MI) biosensor that employs Dynabeads as a magnetic label to capture the GFAP molecules. We demonstrated the detection of recombinant GFAP protein in phosphate-buffered saline (PBS) and in mouse blood samples (detection limit 0.01 ng/mL) and of physiological GFAP in blood and plasma samples (detection limit 1.0 ng/mL) obtained from acute stroke patients. This detection level is within the range of cut-off levels required for clinical stroke subtype differentiation. This platform has the potential to be incorporated into a small device with further development to assist in the classification of acute stroke patients and clinical decision-making at the point-of-care.

Biomarkers for Transient Ischemic Attack: A Brief Perspective of Current Reports and Future Horizons

Cerebrovascular disease is the leading cause of long-term disability in the world and the third-leading cause of death in the United States. The early diagnosis of transient ischemic attack (TIA) is of great importance for reducing the mortality and morbidity of cerebrovascular diseases. Patients with TIA have a high risk of early subsequent ischemic stroke and the development of permanent nervous system lesions. The diagnosis of TIA remains a clinical diagnosis that highly relies on the patient's medical history assessment. There is a growing list of biomarkers associated with different components of the ischemic cascade in the brain. In this review, we take a closer look at the biomarkers of TIA and their validity with a focus on the more clinically important ones using recent evidence of their reliability for practical usage.

Blood GFAP as an emerging biomarker in brain and spinal cord disorders

Blood-derived biomarkers for brain and spinal cord diseases are urgently needed. The introduction of highly sensitive immunoassays led to a rapid increase in the number of potential blood-derived biomarkers for diagnosis and monitoring of neurological disorders. In 2018, the FDA authorized a blood test for clinical use in the evaluation of mild traumatic brain injury (TBI). The test measures levels of the astrocytic intermediate filament glial fibrillary acidic protein (GFAP) and neuroaxonal marker ubiquitin carboxy-terminal hydrolase L1. In TBI, blood GFAP levels are correlated with clinical severity and extent of intracranial pathology. Evidence also indicates that blood GFAP levels hold the potential to reflect, and might enable prediction of, worsening of disability in individuals with progressive multiple sclerosis. A growing body of evidence suggests that blood GFAP levels can be used to detect even subtle injury to the CNS. Most importantly, the successful completion of the ongoing validation of point-of-care platforms for blood GFAP might ameliorate the decision algorithms for acute neurological diseases, such as TBI and stroke, with important economic implications. In this Review, we provide a systematic overview of the evidence regarding the utility of blood GFAP as a biomarker in neurological diseases. We propose a model for GFAP concentration dynamics in different conditions and discuss the limitations that hamper the widespread use of GFAP in the clinical setting. In our opinion, the clinical use of blood GFAP measurements has the potential to contribute to accelerated diagnosis and improved prognostication, and represents an important step forward in the era of precision medicine.

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.

A Longitudinal, Observational Analysis of Neuronal Injury Biomarkers in a Case Report of a Patient With Paraneoplastic Anti-CRMP5 Antibody-Associated Transverse Myelitis

Biomarkers are needed to guide therapeutic decision making in autoimmune and paraneoplastic neurologic disorders. Here, we describe a case of paraneoplastic collapsing response-mediator protein-5 (CRMP5)-associated transverse myelitis (TM) where plasma neurofilament light (NfL) chain and glial fibrillary protein (GFAP) levels were observed over a 14-month clinical course, correlating with radiographical and clinical outcome measures in response to treatment. Blood and CSF samples obtained at diagnosis as well as 7 and 14 months into treatment. At the time of initial diagnosis, both plasma NfL (782.62 pg/ml) and GFAP (283.26 pg/ml) were significantly elevated. Initial treatment was with IV steroids and plasma exchange (PLEX) followed by neuroendocrine tumor removal, chemotherapy, and radiation. After initial improvement with chemotherapy, the patient experienced clinical worsening and transient elevation of plasma NfL (103.27 pg/ml and GFAP (211.58 pg/ml) levels. Whole body positron emission tomography PET scan did not demonstrate recurrence of malignancy. Repeat PLEX and rituximab induction resulted in improvements in patient function, neurologic exam, and plasma biomarker levels. To our knowledge, this is the first described longitudinal, prospective analysis of neuronal injury biomarkers and association of clinical treatment outcomes in CRMP5 myelitis. Our findings suggest that clinical improvement correlates with NfL and GFAP concentrations.

A Novel Combination of Blood Biomarkers and Clinical Stroke Scales Facilitates Detection of Large Vessel Occlusion Ischemic Strokes

Acute ischemic stroke caused by large vessel occlusions (LVOs) is a major contributor to stroke deaths and disabilities; however, identification for emergency treatment is challenging. We recruited two separate cohorts of suspected stroke patients and screened a panel of blood-derived protein biomarkers for LVO detection. Diagnostic performance was estimated by using blood biomarkers in combination with NIHSS-derived stroke severity scales. Multivariable analysis demonstrated that D-dimer (OR 16, 95% CI 5–60; p-value < 0.001) and GFAP (OR 0.002, 95% CI 0–0.68; p-value < 0.05) comprised the optimal panel for LVO detection. Combinations of D-dimer and GFAP with a number of stroke severity scales increased the number of true positives, while reducing false positives due to hemorrhage, as compared to stroke scales alone (p-value < 0.001). A combination of the biomarkers with FAST-ED resulted in the highest accuracy at 95% (95% CI: 87–99%), with sensitivity of 91% (95% CI: 72–99%), and specificity of 96% (95% CI: 90–99%). Diagnostic accuracy was confirmed in an independent cohort, in which accuracy was again shown to be 95% (95% CI: 87–99%), with a sensitivity of 82% (95% CI: 57–96%), and specificity of 98% (95% CI: 92–100%). Accordingly, the combination of D-dimer and GFAP with stroke scales may provide a simple and highly accurate tool for identifying LVO patients, with a potential impact on time to treatment.

Scalable Bio Marker Combinations for Early Stroke Diagnosis: A Systematic Review

Background: Acute stroke treatment is a time-critical process in which every minute counts. Laboratory biomarkers are needed to aid clinical decisions in the diagnosis. Although imaging is critical for this process, these biomarkers may provide additional information to distinguish actual stroke from its mimics and monitor patient condition and the effect of potential neuroprotective strategies. For such biomarkers to be effectively scalable to public health in any economic setting, these must be cost-effective and non-invasive. We hypothesized that blood-based combinations (panels) of proteins might be the key to this approach and explored this possibility through a systematic review. Methods: We followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines for systematic review. Initially, the broader search for biomarkers for early stroke diagnosis yielded 704 hits, and five were added manually. We then narrowed the search to combinations (panels) of the protein markers obtained from the blood. Results: Twelve articles dealing with blood-based panels of protein biomarkers for stroke were included in the systematic review. We observed that NR2 peptide (antibody against the NR2 fragment) and glial fibrillary acidic protein (GFAP) are brain-specific markers related to stroke. Von Willebrand factor (vWF), matrix metalloproteinase 9 (MMP-9), and S100β have been widely used as biomarkers, whereas others such as the ischemia-modified albumin (IMA) index, antithrombin III (AT-III), and fibrinogen have not been evaluated in combination. We herein propose the following new combination of biomarkers for future validation: panel 1 (NR2 + GFAP + MMP-9 + vWF + S100β), panel 2 (NR2 + GFAP + MMP-9 + vWF + IMA index), and panel 3 (NR2 + GFAP + AT-III + fibrinogen). Conclusions: More research is needed to validate, identify, and introduce these panels of biomarkers into medical practice for stroke recurrence and diagnosis in a scalable manner. The evidence indicates that the most promising approach is to combine different blood-based proteins to provide diagnostic precision for health interventions. Through our systematic review, we suggest three novel biomarker panels based on the results in the literature and an interpretation based on stroke pathophysiology.

Acute Stroke Biomarkers: Are We There Yet?

Background: Distinguishing between stroke subtypes and knowing the time of stroke onset are critical in clinical practice. Thrombolysis and thrombectomy are very effective treatments in selected patients with acute ischemic stroke. Neuroimaging helps decide who should be treated and how they should be treated but is expensive, not always available and can have contraindications. These limitations contribute to the under use of these reperfusion therapies.

Aim: An alternative approach in acute stroke diagnosis is to identify blood biomarkers which reflect the body's response to the damage caused by the different types of stroke. Specific blood biomarkers capable of differentiating ischemic from hemorrhagic stroke and mimics, identifying large vessel occlusion and capable of predicting stroke onset time would expedite diagnosis and increase eligibility for reperfusion therapies.

Summary of Review: To date, measurements of candidate biomarkers have usually occurred beyond the time window for thrombolysis. Nevertheless, some candidate markers of brain tissue damage, particularly the highly abundant glial structural proteins like GFAP and S100β and the matrix protein MMP-9 offer promising results. Grouping of biomarkers in panels can offer additional specificity and sensitivity for ischemic stroke diagnosis. Unbiased “omics” approaches have great potential for biomarker identification because of greater gene, protein, and metabolite coverage but seem unlikely to be the detection methodology of choice because of their inherent cost.

Conclusion: To date, despite the evolution of the techniques used in their evaluation, no individual candidate or multimarker panel has proven to have adequate performance for use in an acute clinical setting where decisions about an individual patient are being made. Timing of biomarker measurement, particularly early when decision making is most important, requires urgent and systematic study.

Intrahematomal Ultrasound Enhances RtPA-Fibrinolysis in a Porcine Model of Intracerebral Hemorrhage

Catheter-based ultrasound-thrombolysis has been successfully used in a small clinical trial in order to enhance recombinant tissue plasminogen activator (rtPA)-fibrinolysis, for the treatment of spontaneous intracerebral hemorrhages (ICHs). The aim of this study was to investigate the ultra-early effects of ultrasound on hematoma and the surrounding brain tissue in a porcine ICH-model. To achieve this, 21 pigs with a right frontal ICH were randomly assigned to four groups: (1) drainage (n = 3), (2) drainage + rtPA (n = 6), (3) drainage + ultrasound (n = 6), and (4) drainage + ultrasound + rtPA (n = 6). The hematoma volume assessment was performed using cranial MRI before and after the treatments. Subsequently, the brain sections were analyzed using HE-staining and immunohistochemistry. The combined treatment using rtPA and ultrasound led to a significantly higher hematoma reduction (62 ± 5%) compared to the other groups (Group 1: 2 ± 1%; Group 2: 30 ± 12%; Group 3: 18 ± 8% (p < 0.0001)). In all groups, the MRI revealed an increase in diffusion restriction but neither hyper- or hypoperfusion, nor perihematomal edema. HE stains showed perihematomal microhemorrhages were equally distributed in each group, while edema was more pronounced within the control group. Immunohistochemistry did not reveal any ultra-early side effects. The combined therapy of drainage, rtPA and ultrasound is a safe and effective technique for hematoma-reduction and protection of the perihematomal tissue in regard to ultra-early effects.

Blood Biomarkers for Detection of Brain Injury in COVID-19 Patients

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus attacks multiple organs of coronavirus disease 2019 (COVID-19) patients, including the brain. There are worldwide descriptions of neurological deficits in COVID-19 patients. Central nervous system (CNS) symptoms can be present early in the course of the disease. As many as 55% of hospitalized COVID-19 patients have been reported to have neurological disturbances three months after infection by SARS-CoV-2. The mutability of the SARS-COV-2 virus and its potential to directly affect the CNS highlight the urgency of developing technology to diagnose, manage, and treat brain injury in COVID-19 patients. The pathobiology of CNS infection by SARS-CoV-2 and the associated neurological sequelae of this infection remain poorly understood. In this review, we outline the rationale for the use of blood biomarkers (BBs) for diagnosis of brain injury in COVID-19 patients, the research needed to incorporate their use into clinical practice, and the improvements in patient management and outcomes that can result. BBs of brain injury could potentially provide tools for detection of brain injury in COVID-19 patients. Elevations of BBs have been reported in cerebrospinal fluid (CSF) and blood of COVID-19 patients. BB proteins have been analyzed in CSF to detect CNS involvement in patients with infectious diseases, including human immunodeficiency virus and tuberculous meningitis. BBs are approved by the U.S. Food and Drug Administration for diagnosis of mild versus moderate traumatic brain injury and have identified brain injury after stroke, cardiac arrest, hypoxia, and epilepsy. BBs, integrated with other diagnostic tools, could enhance understanding of viral mechanisms of brain injury, predict severity of neurological deficits, guide triage of patients and assignment to appropriate medical pathways, and assess efficacy of therapeutic interventions in COVID-19 patients.

Early Serum Biomarkers for Intensive Care Unit Treatment within the First 24 Hours in Patients with Intracerebral Hemorrhage

BACKGROUND

 The prognostic significance of serum biomarkers in patients with intracerebral hemorrhage (ICH) is not well investigated concerning inhospital mortality (IHM) and cardiopulmonary events within the first 24 hours of intensive care unit (ICU) treatment. The influence of troponin I (TNI) value and cortisol value (CV) on cardiopulmonary events within the first 24 hours of ICU treatment was reported in subarachnoid hemorrhage patients, but not in ICH patients up to now. The aim of this study was to investigate the role of early serum biomarkers on IHM and TNI value and CV on cardiopulmonary events within the first 24 hours of ICU treatment.

PATIENTS AND METHODS

 A total of 329 patients with spontaneous ICH were retrospectively analyzed. Blood samples were taken on admission to measure serum biomarkers. The TNI value and CV were defined as biomarkers for cardiopulmonary stress. Demographic data, cardiopulmonary parameters, including norepinephrine application rate (NAR) in microgram per kilogram per minute and inspiratory oxygen fraction (FiO₂) within the first 24 hours, and treatment regime were analyzed concerning their impact on ICU treatment and in hospital outcome. Binary logistic analysis was used to identify independent prognostic factors for IHM.

RESULTS

 Patients with initially nonelevated CVs required higher NAR (p = 0.01) and FiO₂ (p = 0.046) within the first 24 hours of ICU treatment. Lower cholinesterase level (p = 0.004), higher NAR (p = 0.002), advanced age (p < 0.0001), larger ICH volume (p < 0.0001), presence of intraventricular hemorrhage (p = 0.007) and hydrocephalus (p = 0.009), raised level of C-reactive protein (p = 0.024), serum lactate (p = 0.003), and blood glucose (p = 0.05) on admission were significantly associated with IHM. In a multivariate model, age (odds ratio [OR]: 1.055; 95% confidence interval [CI]: 1.026-1.085; p < 0.0001), ICH volume (OR: 1.016; CI: 1.008-1.025; p < 0.0001), and Glasgow Coma Scale (GCS) score (OR: 0.680; CI: 0.605-0.764; p < 0.0001) on admission as well as requiring NAR (OR: 1.171; CI: 1.026-1.337; p = 0.02) and FiO₂ (OR: 0.951; CI: 0.921-0.983, p = 0.003) within the first 24 hours were independent predictors of IHM.

CONCLUSION

 Higher levels of C-reactive protein, serum lactate, blood glucose, and lower cholinesterase level on admission were significantly associated with IHM. Patients with initially nonelevated CVs required higher NAR and FiO₂ within the first 24 hours of ICU treatment. Furthermore, requiring an NAR > 0.5 µg/kg/min or an FiO₂ > 0.21 were identified as additional independent predictors for IHM. These results could be helpful to improve ICU treatment in ICH patients.

Discriminative value of glial fibrillar acidic protein (GFAP) as a diagnostic tool in acute stroke. Individual patient data meta-analysis

Glial fibrillar acidic protein (GFAP) in serum has been evaluated as a promising biomarker to differentiate between intracerebral hemorrhage (ICH) and acute ischemic stroke (AIS). We assessed its value as diagnostic and prognostic tool for ICH through a literature systematic review and individual patient data (IPD) meta-analysis.We performed a systematic search in PubMed database until November 2018 for publications that evaluated GFAP to differentiate AIS and ICH within 4.5 hours after symptoms onset. Thereafter, we invited authors of selected studies to participate in this work by providing IPD from their cohorts. We used standardized individual subject's data to evaluate the association of GFAP concentrations with stroke subtype, demographics, stroke characteristics and factors related with GFAP measurement.From 4 selected studies, we collected data of 340 patients (236 AIS and 104 ICH). Standardized GFAP blood levels were significantly elevated in ICH compared with those with AIS (median and IQR: 0.84 (0.781-1.24), 0.79 (0.74-0.81); p<0.0001). In both stroke types, GFAP concentrations correlated with baseline stroke severity (r=0.27, p<0.0001; r=0.36, p<0.001; for AIS and ICH, respectively) but no correlation was found regarding time to sampling. Limited data precluded the evaluation of GFAP levels and functional outcome.These findings demonstrate substantially different levels of GFAP in the blood of patients with ICH compared with patients with AIS soon after the event, while no association was found with outcome. In summary, GFAP could be a valuable diagnostic tool to assist in medical decision-making and to optimize management of stroke in the acute setting.

Blood biomarkers for the diagnosis and differentiation of stroke: A systematic review and meta-analysis

Background

Correct diagnosis of stroke and its subtypes is pivotal in early stages for optimum treatment.

Aims

The aim of this systematic review and meta-analysis is to summarize the published evidence on the potential of blood biomarkers in the diagnosis and differentiation of stroke subtypes.

Methods

A literature search was conducted for papers published until 20 April 2020 in PubMed, EMBASE, Cochrane Library, TRIP, and Google Scholar databases to search for eligible studies investigating the role of blood biomarkers in diagnosing stroke. Quality assessment was done using modified Quality Assessment of Diagnostic Accuracy Studies questionnaire. Pooled standardized mean difference and 95% confidence intervals were calculated. Presence of heterogeneity among the included studies was investigated using the Cochran's Q statistic and I2 metric tests. If I2 was < 50% then a fixed-effect model was applied else a random-effect model was applied. Risk of bias was assessed using funnel plots and between-study heterogeneity was assessed using meta-regression and sensitivity analyses. Entire statistical analysis was conducted in STATA version 13.0.

Results

A total of 40 studies including patients with 5001 ischemic strokes, 756 intracerebral hemorrhage, 554 stroke mimics, and 1774 healthy control subjects analyzing 25 biomarkers (within 24 h after symptoms onset/after the event) were included in our meta-analysis; 67.5% of studies had moderate evidence of quality. Brain natriuretic peptide, matrix metalloproteinase-9, and D-dimer significantly differentiated ischemic stroke from intracerebral hemorrhage, stroke mimics, and health control subjects ( p < 0.05). Glial fibrillary acidic protein successfully differentiated ischemic stroke from intracerebral hemorrhage (standardized mean difference −1.04; 95% confidence interval −1.46 to −0.63) within 6 h. No studies were found to conduct a meta-analysis of blood biomarkers differentiating transient ischemic attack from healthy controls and stroke mimics.

Conclusion

This meta-analysis highlights the potential of brain natriuretic peptide, matrix metalloproteinase-9, D-dimer, and glial fibrillary acidic protein as diagnostic biomarkers for stroke within 24 h. Results of our meta-analysis might serve as a platform for conducting further targeted proteomics studies and phase-III clinical trials. PROSPERO Registration ID: CRD42019139659.

Neurovascular Unit as a Source of Ischemic Stroke Biomarkers-Limitations of Experimental Studies and Perspectives for Clinical Application

Cerebral stroke, which is one of the most frequent causes of mortality and leading cause of disability in developed countries, often leads to devastating and irreversible brain damage. Neurological and neuroradiological diagnosis of stroke, especially in its acute phase, is frequently uncertain or inconclusive. This results in difficulties in identification of patients with poor prognosis or being at high risk for complications. It also makes difficult identification of these stroke patients who could benefit from more aggressive therapies. In contrary to the cardiovascular disease, no single biomarker is available for the ischemic stroke, addressing the abovementioned issues. This justifies the need for identifying of effective diagnostic measures characterized by high specificity and sensitivity. One of the promising avenues in this area is studies on the panels of biomarkers characteristic for processes which occur in different types and phases of ischemic stroke and represent all morphological constituents of the brains' neurovascular unit (NVU). In this review, we present the current state of knowledge concerning already-used or potentially applicable biomarkers of the ischemic stroke. We also discuss the perspectives for identification of biomarkers representative for different types and phases of the ischemic stroke, as well as for different constituents of NVU, which concentration levels correlate with extent of brain damage and patients' neurological status. Finally, a critical analysis of perspectives on further improvement of the ischemic stroke diagnosis is presented.

Impact of Early C-Reactive Protein/Albumin Ratio on Intra-Hospital Mortality Among Patients with Spontaneous Intracerebral Hemorrhage

Objective: The impact of increased C-reactive protein (CRP)/albumin ratio on intra-hospital mortality has been investigated among patients admitted to general intensive care units (ICU). However, it was not investigated among patients with spontaneous intracerebral hemorrhage (ICH). This study aimed to investigate the impact of CRP/albumin ratio on intra-hospital mortality in patients with ICH. Patients and Methods: This retrospective study was conducted on 379 ICH patients admitted between 02/2008 and 12/2017. Blood samples were drawn upon admission and the patients’ demographic, medical, and radiological data were collected. The identification of the independent prognostic factors for intra-hospital mortality was calculated using binary logistic regression and COX regression analysis. Results: Multivariate regression analysis shows that higher CRP/albumin ratio (odds ratio (OR) = 1.66, 95% confidence interval (CI) = 1.193–2.317, p = 0.003) upon admission is an independent predictor of intra-hospital mortality. Multivariate Cox regression analysis indicated that an increase of 1 in the CRP/albumin ratio was associated with a 15.3% increase in the risk of intra-hospital mortality (hazard ratio = 1.153, 95% CI = 1.005–1.322, p = 0.42). Furthermore, a CRP/albumin ratio cut-off value greater than 1.22 was associated with increased intra-hospital mortality (Youden’s Index = 0.19, sensitivity = 28.8, specificity = 89.9, p = 0.007). Conclusions: A CRP/albumin ratio greater than 1.22 upon admission was significantly associated with intra-hospital mortality in the ICH patients.

Acute symptomatic seizures and epilepsy after mechanical thrombectomy

PURPOSE

The purpose of this study was to assess the incidence of acute symptomatic seizures and poststroke epilepsy (PSE) in a well-characterized cohort of patients treated with mechanical thrombectomy. In addition, we aimed to describe the dynamics of blood markers of brain injury in patients that developed PSE.

METHODS

Participants of the prospective AnStroke Trial of anesthesia method during mechanical thrombectomy were included and acute symptomatic seizures and PSE ascertained by medical records review. Blood markers neurofilament light (NFL), tau, glial fibrillary acidic protein (GFAP), S100 calcium-binding protein B (S100B), and neuron-specific enolase (NSE) were assessed.

RESULTS

A total of 90 patients with acute anterior ischemic stroke were included. Median National Institutes of Health Stroke Scale (NIHSS) at admission to hospital was 18 (IQR 15-22). Recanalization was achieved in 90%. No patients had epilepsy prior to the ischemic stroke. Four patients (4.4%) had acute symptomatic seizures and four patients (4.4%) developed PSE during the follow-up time (to death or last medical records review) of 0-4.5 years (median follow-up 1070 days IQR 777-1306), resulting in a two-year estimated PSE risk of 5.3% (95%CI: 0.2-10.4%). Blood markers of brain injury (NFL, tau, GFAP, S100B, and NSE) were generally above the cohort median in patients that developed PSE.

CONCLUSIONS

The incidence of PSE after mechanical thrombectomy was low in our cohort. All blood biomarkers displayed interesting sensitivity and specificity. However, the number of PSE cases was small and more studies are needed on risk factors for PSE after mechanical thrombectomy. The potential of blood markers of brain injury markers to contribute to assessment of PSE risk should be explored further. This article is part of the Special Issue "Seizures & Stroke".

Neurochemical regulation of the expression and function of glial fibrillary acidic protein in astrocytes

Glial fibrillary acidic protein (GFAP), a type III intermediate filament, is a marker of mature astrocytes. The expression of GFAP gene is regulated by many transcription factors (TFs), mainly Janus kinase-2/signal transducer and activator of transcription 3 cascade and nuclear factor κ-light-chain-enhancer of activated B cell signaling. GFAP expression is also modulated by protein kinase and other signaling molecules that are elicited by neuronal activity and hormones. Abnormal expression of GFAP proteins occurs in neuroinflammation, neurodegeneration, brain edema-eliciting diseases, traumatic brain injury, psychiatric disorders and others. GFAP, mainly in α-isoform, is the major component of cytoskeleton and the scaffold of astrocytes, which is essential for the maintenance of astrocytic structure and shape. GFAP also has highly morphological plasticity because of its quick changes in assembling and polymerizing states in response to environmental challenges. This plasticity and its corresponding cellular morphological changes endow astrocytes the functions of physical barrier between adjacent neurons and stabilizer of extracellular environment. Moreover, GFAP colocalizes and even molecularly associates with many functional molecules. This feature allows GFAP to function as a platform for direct interactions between different molecules. Last, GFAP involves transportation and localization of other functional proteins and thus serves as a protein transport guide in astrocytes. This guiding role of GFAP involves an elastic retraction and extension cytoskeletal network that couples with GFAP reassembling, transporting, and membrane protein recycling machinery. This paper reviews our current understanding of the expression and functions of GFAP as well as their regulation.

Challenges and opportunities in stroke genetics

Stroke, ischaemic stroke and subtypes of ischaemic stroke display substantial heritability. When compared with related vascular conditions, the number of established risk loci reaching genome-wide significance for association with stroke is still in the lower range, particularly for aetiological stroke subtypes such as large artery atherosclerotic stroke or small vessel stroke. Nevertheless, for individual loci substantial progress has been made in determining the specific mechanisms mediating stroke risk. In this review, we present a roadmap for functional follow-up of common risk variants associated with stroke. First, we discuss in silico strategies for characterizing signals in non-coding regions and highlight databases providing information on quantitative trait loci for mRNA and protein expression, as well as methylation, focussing on those with presumed relevance for stroke. Next, we discuss experimental strategies for following up on non-coding risk variants and regions such as massively parallel reporter assays, proteome-wide association studies, and chromatin conformation capture (3C) assays. These and other approaches are relevant for gaining insight into the specific variants and mechanisms mediating genetic stroke risk. Finally, we discuss how genetic findings could influence clinical practice by adding to diagnostic algorithms and eventually improve treatment options for stroke.

High-Throughput Profiling of Circulating Antibody Signatures for Stroke Diagnosis Using Small Volumes of Whole Blood

Accurate stroke recognition during triage can streamline care and afford patients earlier access to life-saving interventions. However, the tools currently available to clinicians for prehospital and early in-hospital identification of stroke are limited. The peripheral immune system is intricately involved in stroke pathology and thus may be targetable for the development of immunodiagnostics. In this preliminary study, we sought to determine whether the circulating antibody pool is altered early in stroke, and whether such alterations could be leveraged for diagnosis. One hundred microliters of peripheral whole blood was sampled from 19 ischemic stroke patients, 17 hemorrhagic stroke patients, and 20 stroke mimics in the acute phase of care. A custom-fabricated high-density peptide array comprising 125,000 unique probes was used to assess the binding characteristics of blood-borne antibodies, and a random forest-based approach was used to select a parsimonious set of probes with an optimal ability to discriminate between groups. The coordinate antibody binding intensities of the top 17 probes identified in our analysis displayed an ability to differentiate the total pool of stroke patients from stroke mimics with 92% sensitivity and 90% specificity, as well as detect hemorrhage with 88% sensitivity and 87% specificity, as determined using a same-set cross-validation. These preliminary findings suggest that stroke-associated alterations in the circulating antibody pool may have clinical utility for diagnosis during triage, and that such a possibility warrants further investigation.

NRGN, S100B and GFAP levels are significantly increased in patients with structural lesions resulting from mild traumatic brain injuries

OBJECTIVE

To determine whether serum neurogranin (NRGN), glial fibrillary acidic protein (GFAP), and calcium-binding protein S100 beta (S100B) levels are associated with traumatic intracranial lesions compared to computed tomography (CT) findings of patients with mild traumatic brain injury (mTBI).

PATIENTS AND METHODS

The cross-sectional study cohort included 48 patients who were admitted to the Emergency Department with a complaint of mTBI, a Glasgow Coma Scale score of 14-15, and at least one symptom of head trauma (i.e., post-traumatic amnesia, nausea or vomiting, post-traumatic seizures, persistent headache, and transient loss of consciousness). Blood samples and CT scans were obtained for all patients within 4 h of injury. Age-matched patients without intracranial traumatic pathology (CT-) were recruited as a control group. Blood samples were measured for NRGN, GFAP, and S100B levels.

RESULTS

Of 48 patients, 24 were CT + and had significantly higher serum NRGN (5.79 vs. 2.95 ng/mL), GFAP (0.59 vs.0.36 ng/mL), and S100B (1.72 vs.0.73 μg/L) levels than those who were CT- (p = 0.001, p = 0.026, and p < 0.001, respectively). ROC curves showed that NRGN, GFAP, and S100B levels were sufficient to distinguish traumatic brain injury in patients with mTBI. At the cut-off value for NRGN of 1.87 ng/mL, sensivity was 83.3%, and specificity was 58.3%. At the cut-off value for GFAP of 0.23 ng/mL, sensivity was 75% and specificity was 62.5%. The optimal cut-off value for S100B was 0.47 μg/L (95.8% sensitivity and 62.5% specificity).

CONCLUSION

This is the first study to evaluate NRGN in human serum after mTBI. We confirmed that NRGN levels were significantly higher in CT + patients than CT- patients in the mTBI patient population. Future studies of larger populations and different age groups (especially pediatric) can help reduce the number of CT scans as a reliable and noninvasive diagnostic tool for evaluating NRGN protein levels in mTBI patients with a low probability of intracranial lesions.

Glial fibrillary acidic protein for the early diagnosis of intracerebral hemorrhage: Systematic review and meta-analysis of diagnostic test accuracy

Background and aims

Glial fibrillary acidic protein (GFAP) has shown promise in several studies for its ability to diagnose intracerebral hemorrhage (ICH). We evaluated the diagnostic accuracy of blood GFAP level to differentiate (ICH) from acute ischemic stroke (AIS) and stroke mimics, both overall, and in the first three hours after symptom onset.

Methods

We searched multiple databases, without language restriction, from inception until December 2017. Hierarchical summary receiver operating characteristic (HSROC) modeling was used to meta-analyze results. We conducted subgroup analyses restricted to blood samples collected within 0–60, 60–120, and 120–180 min time groups after symptom onset, to evaluate diagnostic accuracy in the early pre-hospital phase. Between and within study heterogeneity was explored using meta-regression.

Results

The search identified 199 potentially relevant citations from which 11 studies involving 1297 participants (350 ICH, 947 AIS, or mimic) were included. The pooled sensitivity, specificity, and area under the HSROC curve were 0.756 (95% CI 0.630–0.849), 0.945 (95% CI 0.858–0.980), and 0.904 (95% CI 0.878–0.931), respectively. Differences in assays used, but not the other covariates, partially explained between-study heterogeneity ( p = 0.034). The summary estimates for the 0–60, 60–120, and 120–180 min subgroups were comparable to the primary analysis and there was no statistically significant difference in diagnostic accuracy between subgroups.

Conclusions

GFAP is a promising diagnostic biomarker for ICH diagnosis in the early pre-hospital phase. Test accuracy is affected by assay subtype, but there are still unexplained sources of heterogeneity. High quality, international multi-center trials are warranted to develop and validate a point-of-care GFAP assay for the rapid triage and evaluation of acute stroke in the pre-hospital setting.

Evaluation of alpha-II-spectrin breakdown products as potential biomarkers for early recognition and severity of aneurysmal subarachnoid hemorrhage

This study assessed whether cytoskeletal protein alpha-II spectrin breakdown products (SBDP150, SBDP145, and SBDP120) would identify the presence of aSAH and be associated with severity (GCS score, WFNS grade and survival to hospital discharge). This prospective case-control study, conducted at a tertiary care Level I trauma center, enrolled adult patients with angiography confirmed aSAH who underwent ventriculostomy placement for cerebrospinal fluid (CSF) drainage. There were 40 patients enrolled in the study, 20 with aSAH and 20 control subjects. Patients with aSAH were a mean age of 54 (SD15) and 75% were female. There were significant differences in SBDP150, SBDP145, and SBDP120 CSF levels between patients with and without aSAH (p < 0.001), even in those presenting with a GCS Score of 15 and a WFNS Grade 1. The AUC for distinguishing aSAH from control subjects was 1.0 for SBDP150 and SBDP145, and 0.95 for SBDP120. SBDP150 and SBDP145 both yielded sensitivities and specificities of 100% and SBDP120 was 90% and 100% respectively. Moreover, there were significantly higher levels of SBDP150 and SBDP145 in the non-survivors than in the survivors (p < 0.001). This study demonstrates the potential that SBDP’s have as biomarkers for recognition and severity of aSAH. A larger prospective study is warranted.

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.

Carbon dots based immunosorbent assay for the determination of GFAP in human serum

Glial fibrillary acidic protein (GFAP) is expressed in the central nervous system and the level of GFAP normally rises with brain injury and astroglial tumors. So, serum GFAP is used as a marker for diagnosing various types of brain damage and astroglial tumors. In this study, a new sensor based on carbon dots (CDs) linked with antibodies to specifically detect GFAP in human serum was developed. Anti-GFAP (Ab1) linked with protein A/G agarose resin (PA/G) as a capture antibody (PA/G-Ab1) and anti-GFAP (Ab2) labeled with CDs as a detection antibody (CDs-Ab2) were prepared firstly. Then the CD-linked antibody immunosorbent assay (CLAISA) method was constructed based on the sandwich conjunction reaction among PA/G-Ab1, GFAP, and CDs-Ab2. CLAISA, using the fluorescence of PA/G-Ab1-GFAP-Ab2-CDs as the direct signal, enabled the proposed immunosensor to detect GFAP sensitively with a linear range of 0.10-8.00 ng ml^-1 and a detection limit of 25 pg ml^-1. This method was applied to the determination of GFAP in human serum by the standard addition method, and the results showed high accuracy and precision. Considering the easy synthetic process and excellent performance of CLAISA, this method has great potential to be used to monitor GFAP in the clinic.

Looking for novel, brain-derived, peripheral biomarkers of neurological disorders

The role of blood brain barrier (BBB) is to preserve a precisely regulated environment for proper neuronal signaling. In many of the central nervous system (CNS) pathologies, the function of BBB is altered. Thus, there is a necessity to evaluate a fast, noninvasive and reliable method for monitoring of BBB condition. It seems that revealing the peripheral diagnostic biomarker whose release pattern (concentration, dynamics) will be correlated with clinical symptoms of neurological disorders offers significant hope. It could help with faster diagnosis and efficient treatment monitoring. In this review we summarize the recent data concerning exploration of potential new serum biomarkers appearing in the peripheral circulation following BBB disintegration, with an emphasis on epilepsy, traumatic brain injury (TBI) and stroke. We consider the application of well-known proteins (S100β and GFAP) as serum indicators in the light of recently obtained results. Furthermore, the utility of molecules like MMP-9, UCHL-1, neurofilaments, BDNF, and miRNA, which are newly recognized as a potential serum biomarkers, will also be discussed.

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

A Systematic Review of the Usefulness of Glial Fibrillary Acidic Protein for Predicting Acute Intracranial Lesions following Head Trauma

Background

The extensive use of computed tomography (CT) after acute head injury is costly and carries potential iatrogenic risk. This systematic review examined the usefulness of blood-based glial fibrillary acidic protein (GFAP) for predicting acute trauma-related CT-positive intracranial lesions following head trauma. The main objective was to summarize the current evidence on blood-based GFAP as a potential screening test for acute CT-positive intracranial lesions following head trauma.

Methods

We screened MEDLINE, EMBASE, PsychInfo, CINAHL, Web of Science, the Cochrane Database, Scopus, Clinical Trials, OpenGrey, ResearchGate, and the reference lists of eligible publications for original contributions published between January 1980 and January 2017. Eligibility criteria included: (i) population: human head and brain injuries of all severities and ages; (ii) intervention: blood-based GFAP measurement ≤24 h post-injury; and (iii) outcome: acute traumatic lesion on non-contrast head CT ≤24 h post-injury. Three authors completed the publication screening, data extraction, and quality assessment of eligible articles.

Results

The initial search identified 4,706 articles, with 51 eligible for subsequent full-text assessment. Twenty-seven articles were ultimately included. Twenty-four (89%) studies reported a positive association between GFAP level and acute trauma-related intracranial lesions on head CT. The area under the receiver operating characteristic curve for GFAP prediction of intracranial pathology ranged from 0.74 to 0.98 indicating good to excellent discrimination. GFAP seemed to discriminate mass lesions and diffuse injury, with mass lesions having significantly higher GFAP levels. There was considerable variability between the measured GFAP averages between studies and assays. No well-designed diagnostic studies with specific GFAP cutoff values predictive of acute traumatic intracranial lesions have been published.

Conclusion

Intracranial CT-positive trauma lesions were associated with elevated GFAP levels in the majority of studies. Methodological heterogeneity in GFAP assessments and the lack of well-designed diagnostic studies with commercially validated GFAP platforms hinder the level of evidence, and variability in levels of GFAP with no clearly established cutoff for abnormality limit the clinical usefulness of the biomarker. However, blood-based GFAP holds promise as a means of screening for acute traumatic CT-positive lesion following head trauma.

Plasma Glial Fibrillary Acidic Protein in the Differential Diagnosis of Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

Plasma GFAP (glial fibrillary acidic protein) has recently emerged as a potential biomarker for the differentiation of acute intracerebral hemorrhage (ICH) from acute ischemic stroke (AIS). We prospectively assessed the diagnostic accuracy of GFAP in the differential diagnosis of ICH.

METHODS

Consecutive patients presenting to the emergency department within 6 hours from symptom onset were evaluated. All patients underwent extensive diagnostic work-up and were classified according to discharge diagnosis in AIS, ICH, subarachnoid hemorrhage, and stroke mimics. GFAP was also measured in healthy volunteers (controls). Baseline stroke severity was evaluated using National Institutes of Health Stroke Scale. Receiver operating characteristic curve analysis was used to identify the optimal cutoff point for the differentiation between subgroups. Correlation analyses of GFAP plasma concentrations with baseline National Institutes of Health Stroke Scale and onset to sampling time were performed with the nonparametric Spearman rank test and fractional polynomial regression, respectively.

RESULTS

Our study population consisted of 270 individuals (AIS: 121, ICH: 34, stroke mimics: 31, subarachnoid hemorrhage: 5, controls: 79). No differences on baseline stroke severity and onset to sampling time were detected between AIS and ICH. Higher median plasma GFAP values were documented in ICH compared with AIS, stroke mimics, and controls (P<0.001). Receiver operating characteristic analysis highlighted a cutoff value of 0.43 ng/mL as the optimal threshold for the differentiation between ICH and AIS (sensitivity: 91%, specificity: 97%). No association was detected between plasma GFAP concentrations and baseline stroke severity for both AIS (P=0.515) and ICH (P=0.387). In the fractional polynomial analysis, the association between GFAP concentration and onset to sampling time was best described by a J-shaped curve for AIS and an inverted U-shaped curve for ICH, with a peak at 2 hours.

CONCLUSIONS

Plasma GFAP seems to be a sensitive and specific biomarker for the differentiation of ICH from both AIS and other acute neurological disorders, with the optimal diagnostic yield being present in the second hour from symptom onset.

C-Reactive Protein Gene Contributes to the Genetic Susceptibility of Hemorrhagic Stroke in Men: a Case-Control Study in Chinese Han Population

High-sensitivity C-reactive protein (hsCRP) is an inflammatory marker for the prediction and prognosis of ischemic stroke but there is an absence of evidence for cerebral hemorrhagic events. The aim of this study is to investigate the effects of elevated plasma hsCRP and CRP genetic variants on hemorrhagic stroke (HS). Two hundred thirty-six inpatients with HS and 993 age-matched controls from a community-based population were included in a case-control study and four tagging single nucleotide polymorphsims (tagSNPs) at CRP were genotyped. The association of hsCRP elevation and CRP variants with HS was evaluated by multiple logistic regression. HS cases had a higher median (interquartile) of hsCRP with 5.40 (1.30-10.7) mg/L and a proportion of hsCRP elevation (≥3 mg/L, 63.4%) than controls [1.20 (0.80-2.20) mg/L, 16.6%], respectively (P < 0.05 for all). No significant difference of genotype or allele frequency of the four SNPs was observed between HS patients and controls (P > 0.05). Further stratified analysis by gender showed that the variants of rs3093059 (T/C) and rs3091244 (C/T/A) were significantly associated with the decreased risk of HS in men and odds ratios (ORs) and 95% confidence intervals (95% CIs) for additive models were 0.515 (0.294-0.903) and 0.578 (0.349-0.96), respectively, after adjusting for covariates. In HS patients, rs3091244 was positively associated with the hsCRP elevation and rs2794521 was negatively associated with hsCRP elevation (P < 0.05). Our findings suggest that hsCRP elevation is associated with the risk of HS and CRP contributes genetic susceptibility to HS in men as well as hsCRP elevation in HS.

Blood protein biomarkers as diagnostic tool for ischemic stroke: a systematic review

AIM

This systematic review provides a summary of the blood protein biomarkers that have been studied for the diagnosis of acute ischemic stroke.

MATERIALS & METHODS

An extensive MEDLINE (using PubMed) and Web of Knowledge search was performed. From the 354 articles found, 42 were eligible for further analysis and 25 protein biomarkers were examined.

RESULTS

Though many candidate blood-based protein biomarkers were examined, only two could significantly differentiate ischemic stroke patients from healthy controls, stroke mimics and hemorrhagic stroke patients.

CONCLUSION

The blood protein biomarkers, brain natriuretic peptide (BNP) and S100B, were promising biomarkers in diagnosing ischemic stroke. They could be used in cases of diagnostic uncertainty and/or when less experienced healthcare personnel are involved.

Blood-based protein biomarkers for stroke differentiation: A systematic review

Computed tomography (CT) scan is the mainstay for diagnosis of stroke; but the facility of CT scan is not easily available. A blood-based biomarker approach is required to distinguish ischemic stroke (IS) from hemorrhagic stroke (HS) in pre-hospital settings.To conduct a systematic review of diagnostic utility of blood biomarkers for differential diagnosis of stroke.A comprehensive literature search was carried out till March 7, 2017 in PubMed, Cochrane, Medline, OVID, and Google Scholar databases. Methodological quality of each study was assessed using the modified Quality Assessment of Diagnostic Accuracy Studies questionnaire.Eighteen studies were identified relevant to our systematic review. Ten single biomarkers and seven panels of different biomarkers were identified which showed potential for differentiating IS and HS. Activated Protein C- Protein C Inhibitor Complex (APC-PCI) (sensitivity-96%), Glial Fibrillary Acidic Protein (GFAP) (specificity-100%) and a panel of APC-PCI & GFAP (sensitivity- 71%) and Retinol Binding Protein 4 (RBP4) & GFAP (specificity- 100%) were found to have high sensitivity and specificity for differentiating the two stroke types.Our systematic review does not recommend the use of any blood biomarker for clinical purposes yet based on the studies conducted till date.