Serial Sampling of Serum Protein Biomarkers for Monitoring Human Traumatic Brain Injury Dynamics: A Systematic Review

Plasmodium knowlesi Infection Is Associated With Elevated Circulating Biomarkers of Brain Injury and Endothelial Activation

BACKGROUND

Malaria remains a major public health concern with substantial morbidity and mortality worldwide. In Malaysia, the emergence of Plasmodium knowlesi has led to a surge in zoonotic malaria cases and deaths in recent years. Signs of cerebral involvement have been observed in a noncomatose, fatal case of knowlesi infection, but the potential impact of this malaria species on the brain remains unexplored. To address this gap, we investigated circulating levels of brain injury, inflammation, and vascular biomarkers in a cohort of knowlesi-infected patients and controls.

METHODS

Archived plasma samples from 19 Malaysian patients with symptomatic knowlesi infection and 19 healthy, age-matched controls were analyzed. Fifty-two biomarkers of brain injury, inflammation, and vascular activation were measured. Wilcoxon tests were used to examine group differences, and biomarker profiles were explored through hierarchical clustering heatmap analysis.

RESULTS

Bonferroni-corrected analyses revealed significantly elevated brain injury biomarker levels in knowlesi-infected patients, including S100B (P < .0001), Tau (P = .0007), UCH-L1 (P < .0001), αSyn (P < .0001), Park7 (P = .0006), NRGN (P = .0022), and TDP-43 (P = .005). Compared to controls, levels were lower in the infected group for BDNF (P < .0001), CaBD (P < .0001), CNTN1 (P < .0001), NCAM-1 (P < .0001), GFAP (P = .0013), and KLK6 (P = .0126). Hierarchical clustering revealed distinct group profiles for brain injury and vascular activation biomarkers.

CONCLUSIONS

Our findings highlight for the first time a potential impact of P knowlesi infection on the brain, with specific changes in cerebral injury and endothelial activation biomarker profiles. Further studies are warranted to investigate the pathophysiology and clinical significance of these altered markers, through neuroimaging and long-term neurocognitive assessments.

Acute-Phase Neurofilament Light and Glial Fibrillary Acidic Proteins in Cerebrospinal Fluid Predict Long-Term Outcome After Severe Traumatic Brain Injury

BACKGROUND

This study investigated trajectory profiles and the association of concentrations of the biomarkers neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) in ventricular cerebrospinal fluid (CSF) with clinical outcome at 1 year and 10-15 years after a severe traumatic brain injury (sTBI).

METHODS

This study included patients with sTBI at the Neurointensive Care Unit at Sahlgrenska University Hospital, Gothenburg, Sweden. The injury was regarded as severe if patients had a Glasgow Coma Scale ≤ 8 corresponding to Reaction Level Scale ≥ 4. CSF was collected from a ventricular catheter during a 2-week period. Concentrations of NfL and GFAP in CSF were analyzed with enzyme-linked immunosorbent assay. The Glasgow Outcome Scale (GOS) was used to assess the 1-year and 10-15-year outcomes. After adjustment for age and previous neurological diseases, logistic regression was performed for the outcomes GOS 1 (dead) or GOS 2-5 (alive) and GOS 1-3 (poor) or GOS 4-5 (good) versus the independent continuous variables (NfL and GFAP).

RESULTS

Fifty-three patients with sTBI were investigated; forty-seven adults are presented in the article, and six children (aged 7-18 years) are described in Supplement 1. The CSF concentrations of NfL gradually increased over 2 weeks post trauma, whereas GFAP concentrations peaked on days 3-4. Increasing NfL and GFAP CSF concentrations increased the odds of GOS 1-3 outcome 1 year after trauma (odds ratio [OR] 1.73, 95% confidence interval [CI] 1.07-2.80, p = 0.025; and OR 1.61, 95% CI 1.09-2.37, p = 0.016, respectively). Similarly, increasing CSF concentrations of NfL and GFAP increased the odds for GOS 1-3 outcome 10-15 years after trauma (OR 2.04, 95% CI 1.05-3.96, p = 0.035; and OR 1.60, 95% CI 1.02-2.00, p = 0.040).

CONCLUSIONS

This study shows that initial high concentrations of NfL and GFAP in CSF are both associated with higher odds for GOS 1-3 outcome 1 year and 10-15 years after an sTBI, implicating its potential usage as a prognostic marker in the future.

Fluid biomarkers of chronic traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of long-term disability across the world. Evidence for the usefulness of imaging and fluid biomarkers to predict outcomes and screen for the need to monitor complications in the acute stage is steadily increasing. Still, many people experience symptoms such as fatigue and cognitive and motor dysfunction in the chronic phase of TBI, where objective assessments for brain injury are lacking. Consensus criteria for traumatic encephalopathy syndrome, a clinical syndrome possibly associated with the neurodegenerative disease chronic traumatic encephalopathy, which is commonly associated with sports concussion, have been defined only recently. However, these criteria do not fit all individuals living with chronic consequences of TBI. The pathophysiology of chronic TBI shares many similarities with other neurodegenerative and neuroinflammatory conditions, such as Alzheimer disease. As with Alzheimer disease, advancements in fluid biomarkers represent one of the most promising paths for unravelling the chain of pathophysiological events to enable discrimination between these conditions and, with time, provide prediction modelling and therapeutic end points. This Review summarizes fluid biomarker findings in the chronic phase of TBI (≥6 months after injury) that demonstrate the involvement of inflammation, glial biology and neurodegeneration in the long-term complications of TBI. We explore how the biomarkers associate with outcome and imaging findings and aim to establish mechanistic differences in biomarker patterns between types of chronic TBI and other neurodegenerative conditions. Finally, current limitations and areas of priority for future fluid biomarker research are highlighted.

Neuroinflammation in Severe COVID-19: The Dynamics of Inflammatory and Brain Injury Markers During Hospitalization

Patients with COVID-19 can develop excessive inflammation in the brain and consequent neurological complications. The aim of this study was to evaluate the inflammatory, endothelial and brain injury markers in hospitalized COVID-19 patients and compare those with or without neurological symptoms. A total of 30 intensive care unit (ICU) COVID-19 patients were allocated into COVID-19 (without neurological symptoms) or neuro-COVID-19 (with neurological symptoms) groups. Patients with respiratory infection symptoms but negative for COVID-19 were included as a control group. Peripheral blood samples were collected at hospital admission (T1) (controls and ICU patients) and during hospitalization (T2: last 72 h before hospital discharge or in-hospital death) (ICU COVID-19 patients) to analyze inflammatory markers. Higher ICAM-1, CCL26 and VEGF at T1 were identified in both COVID-19 groups compared with control. Neuro-COVID-19 patients presented lower systemic BDNF levels compared with the control group and increased S100B compared with the control and COVID-19 groups. BDNF levels in survivors were lower in the neuro-COVID-19 group compared to the COVID-19 group, while S100B were higher, regardless of the outcome. In addition, all COVID-19 patients presented increased ICAM-1 and CCL26 levels over the hospitalization period (T2 > T1). Furthermore, S100B, ICAM-1, CCL26 and VEGF levels increased in relation to T1 in neuro-COVID-19 patients, with S100B and CCL26 being significantly higher in relation to the COVID-19 group. In conclusion, high levels of brain injury biomarkers were found in patients with neuro-COVID-19, indicating neuroinflammatory and consequent brain injury in the last 72 h of hospitalization.

Regulatory Peptide Pro-Gly-Pro Accelerates Neuroregeneration of Primary Neuroglial Culture after Mechanical Injury in Scratch Test

The scratch test is used as an experimental in vitro model of mechanical damage to primary neuronal cultures to study the mechanisms of cell death in damaged areas. The involvement of NMDA receptors in processes leading to delayed neuronal death, due to calcium dysregulation and synchronous mitochondrial depolarization, has been previously demonstrated. In this study, we explored the neuroregenerative potential of Pro-Gly-Pro (PGP)-an endogenous regulatory peptide with neuroprotective and anti-inflammatory properties and a mild chemoattractant effect. Mechanical injury to the primary neuroglial culture in the form of a scratch caused acute disruption of calcium homeostasis and mitochondrial functions. This was accompanied by neuronal death alongside changes in the profile of neuronal markers (BDNF, NSE and GFAP). In another series of experiments, under subtoxic doses of glutamate (Glu, 33 μM), delayed changes in [Ca2+]i and ΔΨm, i.e., several days after scratch application, were more pronounced in cells in damaged neuroglial cultures. The percentage of cells that restored the initial level of [Ca2+]i (p < 0.05) and the rate of recovery of ΔΨm (p < 0.01) were decreased compared with undamaged cells. Prophylactic application of PGP (100 μM, once) prevented the increase in [Ca2+]i and the sharp drop in mitochondrial potential [ΔΨm] at the time of scratching. Treatment with PGP (30 μM, three or six days) reduced the delayed Glu-induced disturbances in calcium homeostasis and cell death. In the post-glutamate period, the surviving neurons more effectively restored the initial levels of [Ca2+]i (p < 0.001) and Ψm (p < 0.0001). PGP also increased intracellular levels of BDNF and reduced extracellular NSE. In the context of the peptide's therapeutic effect, the recovery of the damaged neuronal network occurred faster due to reduced astrogliosis and increased migration of neurons to the scratch area. Thus, the peptide PGP has a neuroprotective effect, increasing the survival of neuroglial cells after mechanical trauma in vitro by reducing cellular calcium overload and preventing mitochondrial dysfunction. Additionally, the tripeptide limits the post-traumatic consequences of mechanical damage: it reduces astrogliosis and promotes neuronal regeneration.

Research advancement in fluid biomarkers for Parkinson's disease

INTRODUCTION

Diagnostic criteria for Parkinson's disease (PD) rely on clinical, mainly motor, features, implying that pre-motor phase cannot be accurately identified. To achieve a reliable early diagnosis, similar to what has been done for Alzheimer's disease (AD), a shift from clinical to biological identification of PD is being pursued. This shift has taken great advantage from the research on cerebrospinal fluid (CSF) biomarkers as they mirror the ongoing molecular pathogenic mechanisms taking place in PD, thus intercepting the disease timely with respect to clinical manifestations.

AREAS COVERED

CSF α-synuclein seed amplification assay (αS-SAA) has emerged as the most promising biomarker of α-synucleinopathy. CSF biomarkers reflecting AD-pathology and axonal damage (neurofilament light chain) and a novel marker of dopaminergic dysfunction (DOPA decarboxylase) add valuable diagnostic and prognostic information in the neurochemical characterization of PD.

EXPERT OPINION

A biological classification system of PD, encompassing pathophysiological and staging biomarkers, might ensure both early identification and prognostic characterization of the patients. This approach could allow for the best setting for disease-modifying treatments which are currently under investigation.

Blood-based biomarkers of neuronal and glial injury in active major neuropsychiatric systemic lupus erythematosus

BACKGROUND

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a poorly understood and heterogeneous manifestation of SLE. Common major NPSLE syndromes include strokes, seizures, myelitis, and aseptic meningitis. Easily obtainable biomarkers are needed to assist in early diagnosis and improve outcomes for NPSLE. A frequent end-result of major syndromes is neuronal or glial injury. Blood-based neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) have been utilized as markers for monitoring disease activity and/or severity in other neurodegenerative and neuroinflammatory diseases; however, they have not been evaluated in active major NPSLE.

METHODS

This was a case-control study. We enrolled patients aged 12-60 years with active major NPSLE, SLE without active major NPSLE, and healthy controls. Active NPSLE was defined as being <6 months from last new or worsening neuropsychiatric symptom. Demographics, clinical data, and serum or plasma biosamples were collected.

RESULTS

Thirteen patients with active major NPSLE, 13 age/sex/kidney function matched SLE controls without active major NPSLE, and 13 age/sex matched healthy controls (mean ages 26.8, 27.3, 26.6 years) were included. 92% of each group were female. Major syndromes included stroke (5), autonomic disorder (3), demyelinating disease (2), aseptic meningitis (2), sensorimotor polyneuropathy (2), cranial neuropathy (1), seizures (1), and myelopathy (2). Mean (standard deviation) blood NfL and GFAP were 3.6 pg/ml (2.0) and 50.4 pg/ml (15.0), respectively, for the healthy controls. Compared to healthy controls, SLE without active major NPSLE had mean blood NfL and GFAP levels 1.3 pg/ml (p = .42) and 1.2 pg/ml higher (p = .53), respectively. Blood NfL was on average 17.9 pg/ml higher (95% CI: 9.2, 34.5; p < .001) and blood GFAP was on average 3.2 pg/ml higher (95% CI: 1.9, 5.5; p < .001) for cases of active major NPSLE compared to SLE without active major NPSLE. In a subset of 6 patients sampled at multiple time points, blood NfL and GFAP decreased after immunotherapy.

CONCLUSIONS

Blood NfL and GFAP levels are elevated in persons with SLE with active major NPSLE compared to disease matched controls and may lower after immunotherapy initiation. Larger and longitudinal studies are needed to ascertain their utility in a clinical setting.

Evidence for Altered White Matter Organization After Mild Traumatic Brain Injury: A Scoping Review on the Use of Diffusion Magnetic Resonance Imaging and Blood-Based Biomarkers to Investigate Acute Pathology and Relationship to Persistent Post-Concussion Symptoms

Mild traumatic brain injury (mTBI) is the most common form of traumatic brain injury. Post-concussive symptoms typically resolve after a few weeks although up to 20% of people experience these symptoms for >3 months, termed persistent post-concussive symptoms (PPCS). Subtle white matter (WM) microstructural damage is thought to underlie neurological and cognitive deficits experienced post-mTBI. Evidence suggests that diffusion magnetic resonance imaging (dMRI) and blood-based biomarkers could be used as surrogate markers of WM organization. We conducted a scoping review according to PRISMA-ScR guidelines, aiming to collate evidence for the use of dMRI and/or blood-based biomarkers of WM organization, in mTBI and PPCS, and document relationships between WM biomarkers and symptoms. We focused specifically on biomarkers of axonal or myelin integrity post-mTBI. Biomarkers excluded from this review therefore included the following: astroglial, perivascular, endothelial, and inflammatory markers. A literature search performed across four databases, EMBASE, Scopus, Google Scholar, and ProQuest, identified 100 records: 68 analyzed dMRI, 28 assessed blood-based biomarkers, and 4 used both. Blood biomarker studies commonly assessed axonal cytoskeleton proteins (i.e., tau); dMRI studies assessed measures of WM organization (i.e., fractional anisotropy). Significant biomarker alterations were frequently associated with heightened symptom burden and prolonged recovery time post-injury. These data suggest that dMRI and blood-based biomarkers may be useful proxies of WM organization, although few studies assessed these complementary measures in parallel, and the relationship between modalities remains unclear. Further studies are warranted to assess the benefit of a combined biomarker approach in evaluating alterations to WM organization after mTBI.

Blood Biomarkers for the Management of Mild Traumatic Brain Injury in Clinical Practice

BACKGROUND

Despite the use of validated guidelines in the management of mild traumatic brain injury (mTBI), processes to limit unnecessary brain scans are still not sufficient and need to be improved. The use of blood biomarkers represents a relevant adjunct to identify patients at risk for intracranial injury requiring computed tomography (CT) scan.

CONTENT

Biomarkers currently recommended in the management of mTBI in adults and children are discussed in this review. Protein S100 beta (S100B) is the best-documented blood biomarker due to its validation in large observational and interventional studies. Glial fibrillary acidic protein (GFAP) and ubiquitin carboxyterminal hydrolase L-1 (UCH-L1) have also recently demonstrated their usefulness in patients with mTBI. Preanalytical, analytical, and postanalytical performance are presented to aid in their interpretation in clinical practice. Finally, new perspectives on biomarkers and mTBI are discussed.

SUMMARY

In adults, the inclusion of S100B in Scandinavian and French guidelines has reduced the need for CT scans by at least 30%. S100B has significant potential as a diagnostic biomarker, but limitations include its rapid half-life, which requires blood collection within 3 h of trauma, and its lack of neurospecificity. In 2018, the FDA approved the use of combined determination of GFAP and UCH-L1 to aid in the assessment of mTBI. Since 2022, new French guidelines also recommend the determination of GFAP and UCH-L1 in order to target a larger number of patients (sampling within 12 h post-injury) and optimize the reduction of CT scans. In the future, new cut-offs related to age and promising new biomarkers are expected for both diagnostic and prognostic applications.

Rosuvastatin attenuates total-tau serum levels and increases expression of miR-124-3p in dyslipidemic Alzheimer's patients: a historic cohort study

microRNAs are candidate diagnostic biomarkers for Alzheimer's disease. This study aimed to compare Silymarin with Rosuvastatin and placebo on total-Tau protein level and expression levels of microRNAs and TGF-β and COX-2 in Alzheimer's patients with secondary dyslipidemia. 36 mild AD patients with dyslipidemia were divided into three groups of 12. The first group received silymarin (140mg), the second group received placebo (140mg), and the third group recieved Rosuvastatin (10mg). Tablets were administered three times a day for Six months. The blood samples of the patients were collected before and after the intervention and the serum was separated. Using the RT-qPCR method, the expression levels of miR-124-3p and miR-125b-5p were assessed, and the serum levels of total-Tau, TGF-β, and COX-2 enzyme were measured using the ELISA method. Data were analyzed with SPSS software. In this study, the level of Δtotal-Tau was significantly lower in the Rosuvastatin group compared to the placebo (P = 0.038). Also, a significant reduction in the level of ΔTGF-β was observed in the Silymarin to Rosuvastatin group (p = 0.046) and ΔmiR-124-3p was significantly increased in the Rosuvastatin compared to the placebo group (p = 0.044). Rosuvastatin outperformed silymarin in decreasing Δtotal-Tau serum levels and enhancing expression of ΔmiR-124-3p, attributed to Rosuvastatin's capacity to lower cholesterol levels and inflammation concurrently. Conversely, silymarin was more effective than Rosuvastatin in reducing levels of ΔTGF-β. Serum miR-124-3p could serve as a promising diagnostic biomarker and a new therapeutic focus in AD.

Glial fibrillary acidic protein, neurofilament light, matrix metalloprotease 3 and fatty acid binding protein 4 as non-invasive brain tumor biomarkers

BACKGROUND

Gliomas are aggressive malignant tumors, with poor prognosis. There is an unmet need for the discovery of new, non-invasive biomarkers for differential diagnosis, prognosis, and management of brain tumors. Our objective is to validate four plasma biomarkers - glial fibrillary acidic protein (GFAP), neurofilament light (NEFL), matrix metalloprotease 3 (MMP3) and fatty acid binding protein 4 (FABP4) - and compare them with established brain tumor molecular markers and survival.

METHODS

Our cohort consisted of patients with benign and malignant brain tumors (GBM = 77, Astrocytomas = 26, Oligodendrogliomas = 23, Secondary tumors = 35, Meningiomas = 70, Schwannomas = 15, Pituitary adenomas = 15, Normal individuals = 30). For measurements, we used ultrasensitive electrochemiluminescence multiplexed immunoassays.

RESULTS

High plasma GFAP concentration was associated with GBM, low GFAP and high FABP4 were associated with meningiomas, and low GFAP and low FABP4 were associated with astrocytomas and oligodendrogliomas. NEFL was associated with progression of disease. Several prognostic genetic alterations were significantly associated with all plasma biomarker levels. We found no independent associations between plasma GFAP, NEFL, FABP4 and MMP3, and overall survival. The candidate biomarkers could not reliably discriminate GBM from primary or secondary CNS lymphomas.

CONCLUSIONS

GFAP, NEFL, FABP4 and MMP3 are useful for differential diagnosis and prognosis, and are associated with molecular changes in gliomas.

Changes in the levels of serum glial fibrillary acidic protein and the correlation with outcomes in severe traumatic brain injury patients

Purpose

Glial fibrillary acidic protein serves as a biomarker indicative of astroglial injury, particularly following instances of severe traumatic brain injury. This study aims to evaluate variations in serum glial fibrillary acidic protein levels within the first 3 days and their correlation with outcomes in patients with severe traumatic brain injury.

Subjects and methods

Thirty-nine patients with severe traumatic brain injury were enrolled in the study. Their blood samples were collected at six distinct time points: T0 (upon admission), T1, T2, T3, T4, and T5 (6-, 12-, 24-, 48-, and 72-h post-admission, respectively). The blood samples were run for the quantification of serum glial fibrillary acidic protein levels and other biochemical tests. All patients were closely watched and the outcomes at discharge were evaluated.

Results

Glial fibrillary acidic protein levels tend to increase gradually from the time of admission to 48 h post-admission and then decrease at 72 h post-admission. Glial fibrillary acidic protein T2 is correlated with Acute Physiology and Chronic Health Evaluation II score, lactate, Simplified Acute Physiology Score II score and outcome. Glial fibrillary acidic protein max correlated with lactate, Acute Physiology and Chronic Health Evaluation II score, Simplified Acute Physiology Score II score, and outcome. Glasgow Coma Score at admission and glial fibrillary acidic protein T2 (OR = 1.034; p = 0.025), T3 (OR = 1.029; p = 0.046), T4 (OR = 1.006; p = 0.032), T5 (OR = 1.012; p = 0.048) and glial fibrillary acidic protein max (OR = 1.005; p = 0.010) were independent factors that have significant prognostic value in mortality in patients with severe traumatic brain injury. The predictive model in predicting mortality had the highest area under the curve based on glial fibrillary acidic protein T2 and Glasgow Coma Score T0 with an area under the curve of 0.904 and p < 0.001. In the multivariable regression model, glial fibrillary acidic protein max was associated with Glasgow score (p < 0.001; VIF = 1.585), lactate T0 (p = 0.024; VIF = 1.163), Acute Physiology and Chronic Health Evaluation II score (p = 0.037; VIF = 1.360), and Rotterdam score (p = 0.044; VIF = 1.713).

Conclusion

Glial fibrillary acidic protein levels tend to increase gradually from the time of admission to 48 h post-admission then decreases at 72 h post-admission. Glial fibrillary acidic protein T2, T3, T4, T5, and glial fibrillary acidic protein max were independent factors with significant prognostic mortality values in patients with severe traumatic brain injury.

Biomarkers of Neurobiologic Recovery in Adults With Sport-Related Concussion

Importance

Sport-related concussion (SRC), a form of mild traumatic brain injury, is a prevalent occurrence in collision sports. There are no well-established approaches for tracking neurobiologic recovery after SRC.

Objective

To examine the levels of serum glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) in Australian football athletes who experience SRC.

Design, Setting, and Participants

A cohort study recruiting from April 10, 2021, to September 17, 2022, was conducted through the Victorian Amateur Football Association, Melbourne, Australia. Participants included adult Australian football players with or without SRC. Data analysis was performed from May 26, 2023, to March 27, 2024.

Exposure

Sport-related concussion, defined as at least 1 observable sign and/or 2 or more symptoms.

Main Outcomes and Measures

Primary outcomes were serum GFAP and NfL levels at 24 hours, and 1, 2, 4, 6, 8, 12, and 26 weeks. Secondary outcomes were symptoms, cognitive performance, and return to training times.

Results

Eighty-one individuals with SRC (median age, 22.8 [IQR, 21.3-26.0] years; 89% male) and 56 control individuals (median age, 24.6 [IQR, 22.4-27.3] years; 96% male) completed a total of 945 of 1057 eligible testing sessions. Compared with control participants, those with SRC exhibited higher GFAP levels at 24 hours (mean difference [MD] in natural log, pg/mL, 0.66 [95% CI, 0.50-0.82]) and 4 weeks (MD, 0.17 [95% CI, 0.02-0.32]), and NfL from 1 to 12 weeks (1-week MD, 0.31 [95% CI, 0.12-0.51]; 2-week MD, 0.38 [95% CI, 0.19-0.58]; 4-week MD, 0.31 [95% CI, 0.12-0.51]; 6-week MD, 0.27 [95% CI, 0.07-0.47]; 8-week MD, 0.36 [95% CI, 0.15-0.56]; and 12-week MD, 0.25 [95% CI, 0.04-0.46]). Growth mixture modeling identified 2 GFAP subgroups: extreme prolonged (16%) and moderate transient (84%). For NfL, 3 subgroups were identified: extreme prolonged (7%), moderate prolonged (15%), and minimal or no change (78%). Individuals with SRC who reported loss of consciousness (LOC) (33% of SRC cases) had higher GFAP at 24 hours (MD, 1.01 [95% CI, 0.77-1.24]), 1 week (MD, 0.27 [95% CI, 0.06-0.49]), 2 weeks (MD, 0.21 [95% CI, 0.004-0.42]) and 4 weeks (MD, 0.34 [95% CI, 0.13-0.55]), and higher NfL from 1 week to 12 weeks (1-week MD, 0.73 [95% CI, 0.42-1.03]; 2-week MD, 0.91 [95% CI, 0.61-1.21]; 4-week MD, 0.90 [95% CI, 0.59-1.20]; 6-week MD, 0.81 [95% CI, 0.50-1.13]; 8-week MD, 0.73 [95% CI, 0.42-1.04]; and 12-week MD, 0.54 [95% CI, 0.22-0.85]) compared with SRC participants without LOC. Return to training times were longer in the GFAP extreme compared with moderate subgroup (incident rate ratio [IRR], 1.99 [95% CI, 1.69-2.34]; NfL extreme (IRR, 3.24 [95% CI, 2.63-3.97]) and moderate (IRR, 1.43 [95% CI, 1.18-1.72]) subgroups compared with the minimal subgroup, and for individuals with LOC compared with those without LOC (IRR, 1.65 [95% CI, 1.41-1.93]).

Conclusions and Relevance

In this cohort study, a subset of SRC cases, particularly those with LOC, showed heightened and prolonged increases in GFAP and NfL levels, that persisted for at least 4 weeks. These findings suggest that serial biomarker measurement could identify such cases, guiding return to play decisions based on neurobiologic recovery. While further investigation is warranted, the association between prolonged biomarker elevations and LOC may support the use of more conservative return to play timelines for athletes with this clinical feature.

Diagnostic Utility of Glial Fibrillary Acidic Protein Beyond 12 Hours After Traumatic Brain Injury: A TRACK-TBI Study

Blood levels of glial fibrillary acidic protein (GFAP) and ubiquitin carboxyl-terminal hydrolase-L1 (UCH-L1) within 12h of suspected traumatic brain injury (TBI) have been approved by the Food and Drug administration to aid in determining the need for a brain computed tomography (CT) scan. The current study aimed to determine whether this context of use can be expanded beyond 12h post-TBI in patients presenting with Glasgow Coma Scale (GCS) 13-15. The prospective, 18-center Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study enrolled TBI participants aged ≥17 years who presented to a United States Level 1 trauma center and received a clinically indicated brain CT scan within 24h post-injury, a blood draw within 24h and at 14 days for biomarker analysis. Data from participants with emergency department arrival GCS 13-15 and biomarker values at days 1 and 14 were extracted for the primary analysis. A subgroup of hospitalized participants with serial biomarkers at days 1, 3, 5, and 14 were analyzed, including plasma GFAP and UCH-L1, and serum neuron-specific enolase (NSE) and S100 calcium-binding protein B (S100B). The primary analysis compared biomarker values dichotomized by head CT results (CT+/CT-). Area under receiver-operating characteristic curve (AUC) was used to determine diagnostic accuracy. The overall cohort included 1142 participants with initial GCS 13-15, with mean age 39.8 years, 65% male, and 73% Caucasian. The GFAP provided good discrimination in the overall cohort at days 1 (AUC = 0.82) and 14 (AUC = 0.72), and in the hospitalized subgroup at days 1 (AUC = 0.84), 3 (AUC = 0.88), 5 (AUC = 0.82), and 14 (AUC = 0.74). The UCH-L1, NSE, and S100B did not perform well (AUC = 0.51-0.57 across time points). This study demonstrates the utility of GFAP to aid in decision-making for diagnostic brain CT imaging beyond the 12h time frame in patients with TBI who have a GCS 13-15.

Neurofilaments as biomarkers in neurological disorders - towards clinical application

Neurofilament proteins have been validated as specific body fluid biomarkers of neuro-axonal injury. The advent of highly sensitive analytical platforms that enable reliable quantification of neurofilaments in blood samples and simplify longitudinal follow-up has paved the way for the development of neurofilaments as a biomarker in clinical practice. Potential applications include assessment of disease activity, monitoring of treatment responses, and determining prognosis in many acute and chronic neurological disorders as well as their use as an outcome measure in trials of novel therapies. Progress has now moved the measurement of neurofilaments to the doorstep of routine clinical practice for the evaluation of individuals. In this Review, we first outline current knowledge on the structure and function of neurofilaments. We then discuss analytical and statistical approaches and challenges in determining neurofilament levels in different clinical contexts and assess the implications of neurofilament light chain (NfL) levels in normal ageing and the confounding factors that need to be considered when interpreting NfL measures. In addition, we summarize the current value and potential clinical applications of neurofilaments as a biomarker of neuro-axonal damage in a range of neurological disorders, including multiple sclerosis, Alzheimer disease, frontotemporal dementia, amyotrophic lateral sclerosis, stroke and cerebrovascular disease, traumatic brain injury, and Parkinson disease. We also consider the steps needed to complete the translation of neurofilaments from the laboratory to the management of neurological diseases in clinical practice.

Comparison of GFAP and UCH-L1 Measurements Using Two Automated Immunoassays (i-STAT® and Alinity®) for the Management of Patients with Mild Traumatic Brain Injury: Preliminary Results from a French Single-Center Approach

The measurement of blood glial fibrillary acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) may assist in the management of mild traumatic brain injury (mTBI). This study aims to compare GFAP and UCH-L1 values measured using a handheld device with those measured using a core laboratory platform. We enrolled 230 mTBI patients at intermediate risk of complications. Following French guidelines, a negative S100B value permits the patient to be discharged without a computed tomography scan. Plasma GFAP and UCH-L1 levels were retrospectively measured using i-STAT® and Alinity® i analyzers in patients managed within 12 h post-trauma. Our analysis indicates a strong correlation of biomarker measurements between the two analyzers. Cohen's kappa coefficients and Lin's concordance coefficients were both ≥0.7, while Spearman's correlation coefficient was 0.94 for GFAP and 0.90 for UCH-L1. Additionally, the diagnostic performance in identifying an intracranial lesion was not significantly different between the two analyzers, with a sensitivity of 100% and specificity of approximately 30%. GFAP and UCH-L1 levels measured using Abbott's i-STAT® and Alinity® i platform assays are highly correlated both analytically and clinically in a cohort of 230 patients managed for mTBI according to French guidelines.

Neurofilament light chain and glial fibrillary acid protein levels are elevated in post-mild COVID-19 or asymptomatic SARS-CoV-2 cases

Given the huge impact of the COVID-19 pandemic, it appears of paramount importance to assess the cognitive effects on the population returning to work after COVID-19 resolution. Serum levels of neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP) represent promising biomarkers of neuro-axonal damage and astrocytic activation. In this cohort study, we explored the association between sNfL and sGFAP concentrations and cognitive performance in a group of 147 adult workers with a previous asymptomatic SARS-CoV-2 infection or mild COVID-19, one week and, in 49 of them, ten months after SARS-Cov2 negativization and compared them to a group of 82 age and BMI-matched healthy controls (HCs). sNfL and sGFAP concentrations were assessed using SimoaTM assay Neurology 2-Plex B Kit. COVID-19 patients were interviewed one-on-one by trained physicians and had to complete a list of questionnaires, including the Cognitive Failure Questionnaire (CFQ). At the first assessment (T0), sNfL and sGFAP levels were significantly higher in COVID-19 patients than in HCs (p < 0.001 for both). The eleven COVID-19 patients with cognitive impairment had significantly higher levels of sNfL and sGFAP than the others (p = 0.005 for both). At the subsequent follow-up (T1), sNfL and sGFAP levels showed a significant decrease (median sNfL 18.3 pg/mL; median sGFAP 77.2 pg/mL), although they were still higher than HCs (median sNfL 7.2 pg/mL, median sGFAP 63.5 pg/mL). Our results suggest an ongoing damage involving neurons and astrocytes after SARS-Cov2 negativization, which reduce after ten months even if still evident compared to HCs.

Biofluid-based Biomarkers in Traumatic Brain Injury: A Narrative Review

Traumatic brain injury (TBI) is a complex condition characterized by a multifaceted pathophysiology. It presents significant diagnostic and prognostic challenges in clinical settings. This narrative review explores the evolving role of biofluid biomarkers as essential tools in the diagnosis, prognosis, and treatment of TBI. In recent times, preclinical and clinical trials utilizing these biofluid biomarkers have been actively pursued internationally. Among the biomarkers for nerve tissue proteins are neuronal biomarkers like neuronal specific enolase and ubiquitin C-terminal hydrolase L1; astroglia injury biomarkers such as S100B and glial fibrillary acidic protein; axonal injury and demyelination biomarkers, including neurofilaments and myelin basic protein; new axonal injury and neurodegeneration biomarkers like total tau and phosphorylated tau; and others such as spectrin breakdown products and microtubule-associated protein 2. The interpretation of these biomarkers can be influenced by various factors, including secretion from organs other than the injury site and systemic conditions. This review highlights the potential of these biomarkers to transform TBI management and emphasizes the need for continued research to validate their efficacy, refine testing platforms, and ultimately improve patient care and outcomes.

Diagnosis and management of subarachnoid haemorrhage

Aneurysmal subarachnoid haemorrhage (aSAH) presents a challenge to clinicians because of its multisystem effects. Advancements in computed tomography (CT), endovascular treatments, and neurocritical care have contributed to declining mortality rates. The critical care of aSAH prioritises cerebral perfusion, early aneurysm securement, and the prevention of secondary brain injury and systemic complications. Early interventions to mitigate cardiopulmonary complications, dyselectrolytemia and treatment of culprit aneurysm require a multidisciplinary approach. Standardised neurological assessments, transcranial doppler (TCD), and advanced imaging, along with hypertensive and invasive therapies, are vital in reducing delayed cerebral ischemia and poor outcomes. Health care disparities, particularly in the resource allocation for SAH treatment, affect outcomes significantly, with telemedicine and novel technologies proposed to address this health inequalities. This article underscores the necessity for comprehensive multidisciplinary care and the urgent need for large-scale studies to validate standardised treatment protocols for improved SAH outcomes.

Serum amyloid A and mitochondrial DNA in extracellular vesicles are novel markers for detecting traumatic brain injury in a mouse model

This study investigates the potential use of circulating extracellular vesicles' (EVs) DNA and protein content as biomarkers for traumatic brain injury (TBI) in a mouse model. Despite an overall decrease in EVs count during the acute phase, there was an increased presence of exosomes (CD63+ EVs) during acute and an increase in microvesicles derived from microglia/macrophages (CD11b+ EVs) and astrocytes (ACSA-2+ EVs) in post-acute TBI phases, respectively. Notably, mtDNA exhibited an immediate elevation post-injury. Neuronal (NFL) and microglial (Iba1) markers increased in the acute, while the astrocyte marker (GFAP) increased in post-acute TBI phases. Novel protein biomarkers (SAA, Hp, VWF, CFD, CBG) specific to different TBI phases were also identified. Biostatistical modeling and machine learning identified mtDNA and SAA as decisive markers for TBI detection. These findings emphasize the importance of profiling EVs' content and their dynamic release as an innovative diagnostic approach for TBI in liquid biopsies.

Concentrations of S100B and neurofilament light chain in blood as biomarkers for checkpoint inhibitor-induced CNS inflammation

BACKGROUND

Cancer treatment with immune checkpoint inhibition (ICI) can cause immune-related adverse events in the central nervous system (CNS irAE). There are no blood biomarkers to detect CNS irAE. We investigated if concentrations of S100-calcium-binding protein B (S100B) and neurofilament light chain (NfL) in blood can be used as biomarkers for CNS irAE and assessed the incidence of CNS irAE in a cohort of ICI-treated patients.

METHODS

In this single-centre, retrospective cohort study, we examined medical records and laboratory data of 197 consecutive patients treated with combined CTLA-4 and PD-1 inhibition (ipilimumab; ipi + nivolumab; nivo) for metastatic melanoma or renal cell carcinoma. CNS irAE was diagnosed using established criteria. Concentrations of S100B and NfL in blood were measured in patients with CNS irAE and in 84 patients without CNS irAE.

FINDINGS

Nine of 197 patients (4.6%) fulfilled criteria for CNS irAE. S100B and NfL in blood increased during CNS inflammation and normalized during immunosuppression. CNS irAE was detected with a sensitivity of 100% (S100B) and 79% (NfL) and a specificity of 89% (S100B) and 74% (NfL). Patients with CNS irAE had simultaneous increased concentration of C-reactive protein (CRP) (9/9) and alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) in blood (8/9).

INTERPRETATION

Analysis of S100B, NfL and CRP in blood facilitates the diagnosis of CNS irAE. CNS irAE may be more common than previously reported. There may be shared immune mechanisms between CNS and hepatitis irAE.

FUNDING

Supported by funding from the Swedish Cancer Foundation, the ALF-agreement, and Jubileumsklinikens Cancerfond.

Serum neurofilament light chain for predicting delayed neurological sequelae after acute carbon monoxide poisoning

INTRODUCTION

Acute carbon monoxide (CO) poisoning survivors may experience persistent delayed neurological sequelae (DNS). No studies have investigated the serum neurofilament light chain (NFL) as a prognostic biomarker in acute CO poisoning. This study aimed to determine the serum NFL levels to predict the DNS after acute CO poisoning.

METHODS

Patients with acute CO poisoning who were consecutively admitted from October 2020 to September 2022 were included. The predictive performance of NFLs for the DNS was assessed through the analyses of the correlation, the logistic regression, and the receiver operating characteristic (ROC) curve.

RESULTS

Overall, 9.7% (15/155) of the patients had DNS. The serum NFLs in patients with DNS was 113.7 pg/mL, which is significantly higher than that in the non-DNS group (25.8 pg/mL; P < 0.001). Correlation analysis shows that the serum NFLs are positively correlated with DNS (r = 0.567, P < 0.001). After multiple adjustments, the serum NFLs are independently correlated with DNS [adjusted odds ratio 1.032; 95% confidence interval (CI) 1.001, 1.064; p = 0.043]. The ROC curve indicates an area under the curve (AUC) of 0.923 (95% CI 0.869, 0.960), with a sensitivity of 100% and a specificity of 84.3% at the best cutoff value of 73.4 pg/mL. Pairwise comparison shows that the AUC of the NFL is significantly higher than that of the neuron specific enolase (AUC = 0.779) using the Hanley and McNeil test (Z = 2.283, p = 0.022).

CONCLUSION

Serum NFL could be a biomarker of the DNS after acute CO poisoning.

Traumatic Brain Injury in the Long-COVID Era

Major determinants of the biological background or reserve, such as age, biological sex, comorbidities (diabetes, hypertension, obesity, etc.), and medications (e.g., anticoagulants), are known to affect outcome after traumatic brain injury (TBI). With the unparalleled data richness of coronavirus disease 2019 (COVID-19; ∼375,000 and counting!) as well as the chronic form, long-COVID, also called post-acute sequelae SARS-CoV-2 infection (PASC), publications (∼30,000 and counting) covering virtually every aspect of the diseases, pathomechanisms, biomarkers, disease phases, symptomatology, etc., have provided a unique opportunity to better understand and appreciate the holistic nature of diseases, interconnectivity between organ systems, and importance of biological background in modifying disease trajectories and affecting outcomes. Such a holistic approach is badly needed to better understand TBI-induced conditions in their totality. Here, I briefly review what is known about long-COVID/PASC, its underlying-suspected-pathologies, the pathobiological changes induced by TBI, in other words, the TBI endophenotypes, discuss the intersection of long-COVID/PASC and TBI-induced pathobiologies, and how by considering some of the known factors affecting the person's biological background and the inclusion of mechanistic molecular biomarkers can help to improve the clinical management of TBI patients.

Preliminary Evaluation of the Scandinavian Guidelines for Initial Management of Minimal, Mild, and Moderate Head Injuries with Glial Fibrillary Acidic Protein

Glial fibrillary acidic protein (GFAP) has become the most promising biomarker for detecting traumatic abnormalities on head computed tomography (CT) in patients with traumatic brain injury (TBI), but most studies have not addressed the potential added value of combining the biomarker with clinical variables that confer risk for intracranial injuries. The Scandinavian Guidelines for Initial Management of Minimal, Mild, and Moderate Head Injuries in Adults were the first clinical decision rules in the field with an incorporated biomarker, the S100 astroglial calcium-binding protein B (S100B), which is used in the Mild (Low Risk) group defined by the guidelines. Our aim was to evaluate the performance of the guidelines when S100B was substituted with GFAP. The sample (N = 296) was recruited from the Tampere University Hospital's emergency department between November 2015 and November 2016, and there were 49 patients with available GFAP results who were stratified in the Mild (Low Risk) group (thus patients undergoing biomarker triaging). A previously reported cutoff of plasma GFAP ≥140 pg/mL was used. Within the Mild (Low Risk) group (n = 49), GFAP sensitivity (with 95% confidence intervals in parentheses) for detecting traumatic CT abnormalities was 1.0 (0.40-1.00), specificity 0.34 (0.19-0.53), the negative predictive value (NPV) 1.0 (0.68-1.00), and the positive predictive value (PPV) 0.16 (0.05-0.37). The sensitivity and specificity of the modified guidelines with GFAP, when applied to all imaged patients (n = 197) in the whole sample, were 0.94 (0.77-0.99) and 0.20 (0.15-0.28), respectively. NPV was 0.94 (0.80-0.99) and PPV 0.18 (0.13-0.25). In the Mild (Low Risk) group, none of the patients with GFAP results below 140 pg/mL had traumatic abnormalities on their head CT. These findings were derived from a small patient subgroup. Future researchers should replicate these findings in larger samples and assess whether GFAP has added or comparable value to S100B in acute TBI management.

Systematic review and evidence gap mapping of biomarkers associated with neurological manifestations in patients with COVID-19

OBJECTIVE

This study aimed to synthesize the existing evidence on biomarkers related to coronavirus disease 2019 (COVID-19) patients who presented neurological events.

METHODS

A systematic review of observational studies (any design) following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and the Cochrane Collaboration recommendations was performed (PROSPERO: CRD42021266995). Searches were conducted in PubMed and Scopus (updated April 2023). The methodological quality of nonrandomized studies was assessed using the Newcastle‒Ottawa Scale (NOS). An evidence gap map was built considering the reported biomarkers and NOS results.

RESULTS

Nine specific markers of glial activation and neuronal injury were mapped from 35 studies published between 2020 and 2023. A total of 2,237 adult patients were evaluated in the included studies, especially during the acute phase of COVID-19. Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) biomarkers were the most frequently assessed (n = 27 studies, 77%, and n = 14 studies, 40%, respectively). Although these biomarkers were found to be correlated with disease severity and worse outcomes in the acute phase in several studies (p < 0.05), they were not necessarily associated with neurological events. Overall, 12 studies (34%) were judged as having low methodological quality, 9 (26%) had moderate quality, and 9 (26%) had high quality.

CONCLUSIONS

Different neurological biomarkers in neurosymptomatic COVID-19 patients were identified in observational studies. Although the evidence is still scarce and conflicting for some biomarkers, well-designed longitudinal studies should further explore the pathophysiological role of NfL, GFAP, and tau protein and their potential use for COVID-19 diagnosis and management.

Clinical descriptors of disease trajectories in patients with traumatic brain injury in the intensive care unit (CENTER-TBI): a multicentre observational cohort study

BACKGROUND

Patients with traumatic brain injury are a heterogeneous population, and the most severely injured individuals are often treated in an intensive care unit (ICU). The primary injury at impact, and the harmful secondary events that can occur during the first week of the ICU stay, will affect outcome in this vulnerable group of patients. We aimed to identify clinical variables that might distinguish disease trajectories among patients with traumatic brain injury admitted to the ICU.

METHODS

We used data from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) prospective observational cohort study. We included patients aged 18 years or older with traumatic brain injury who were admitted to the ICU at one of the 65 CENTER-TBI participating centres, which range from large academic hospitals to small rural hospitals. For every patient, we obtained pre-injury data and injury features, clinical characteristics on admission, demographics, physiological parameters, laboratory features, brain biomarkers (ubiquitin carboxy-terminal hydrolase L1 [UCH-L1], S100 calcium-binding protein B [S100B], tau, neurofilament light [NFL], glial fibrillary acidic protein [GFAP], and neuron-specific enolase [NSE]), and information about intracranial pressure lowering treatments during the first 7 days of ICU stay. To identify clinical variables that might distinguish disease trajectories, we applied a novel clustering method to these data, which was based on a mixture of probabilistic graph models with a Markov chain extension. The relation of clusters to the extended Glasgow Outcome Scale (GOS-E) was investigated.

FINDINGS

Between Dec 19, 2014, and Dec 17, 2017, 4509 patients with traumatic brain injury were recruited into the CENTER-TBI core dataset, of whom 1728 were eligible for this analysis. Glucose variation (defined as the difference between daily maximum and minimum glucose concentrations) and brain biomarkers (S100B, NSE, NFL, tau, UCH-L1, and GFAP) were consistently found to be the main clinical descriptors of disease trajectories (ie, the leading variables contributing to the distinguishing clusters) in patients with traumatic brain injury in the ICU. The disease trajectory cluster to which a patient was assigned in a model was analysed as a predictor together with variables from the IMPACT model, and prediction of both mortality and unfavourable outcome (dichotomised GOS-E ≤4) was improved.

INTERPRETATION

First-day ICU admission data are not the only clinical descriptors of disease trajectories in patients with traumatic brain injury. By analysing temporal variables in our study, variation of glucose was identified as the most important clinical descriptor that might distinguish disease trajectories in the ICU, which should direct further research. Biomarkers of brain injury (S100B, NSE, NFL, tau, UCH-L1, and GFAP) were also top clinical descriptors over time, suggesting they might be important in future clinical practice.

FUNDING

European Union 7th Framework program, Hannelore Kohl Stiftung, OneMind, Integra LifeSciences Corporation, and NeuroTrauma Sciences.

Serum biomarkers of hypoxic-ischemic brain injury

Brain injury is a multifaceted condition arising from nonspecific damage to nervous tissue. The resulting cognitive developmental impairments reverberate through patients' lives, affecting their families, and even the broader economic landscape. The significance of early brain injury detection lies in its potential to stave off severe consequences and enhance the effectiveness of tailored therapeutic interventions. While established methods like neuroimaging and neurophysiology serve as valuable diagnostic tools, their demanding nature restricts their accessibility, particularly in scenarios such as small hospitals, nocturnal or weekend shifts, and cases involving unstable patients. Hence, there is a pressing need for more accessible and efficient diagnostic avenues. Among the spectrum of brain injuries, hypoxic-ischemic encephalopathy stands out as a predominant affliction in the pediatric population. Diagnosing brain injuries in newborns presents challenges due to the subjective nature of assessments like Apgar scores and the inherent uncertainty in neurological examinations. In this context, methods like magnetic resonance and ultrasound hold recommendations for more accurate diagnosis. Recognizing the potential of serum biomarkers derived from blood samples, this paper underscores their promise as a more expedient and resource-efficient means of assessing brain injuries. The review compiles current insights into serum biomarkers, drawing from experiments conducted on animal models as well as human brain pathologies. The authors aim to elucidate specific characteristics, temporal profiles, and the available corpus of experimental and clinical data for serum biomarkers specific to brain injuries. These include neuron-specific enolase (NSE), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), S100 calcium-binding protein beta (S100B), glial fibrillary acidic protein (GFAP), and high-mobility-group-protein-box-1 (HMGB1). This comprehensive endeavor contributes to advancing the understanding of brain injury diagnostics and potential avenues for therapeutic intervention.

Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses

To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1-11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely.

Fluid-Based Protein Biomarkers in Traumatic Brain Injury: The View from the Bedside

There has been an explosion of research into biofluid (blood, cerebrospinal fluid, CSF)-based protein biomarkers in traumatic brain injury (TBI) over the past decade. The availability of very large datasets, such as CENTRE-TBI and TRACK-TBI, allows for correlation of blood- and CSF-based molecular (protein), radiological (structural) and clinical (physiological) marker data to adverse clinical outcomes. The quality of a given biomarker has often been framed in relation to the predictive power on the outcome quantified from the area under the Receiver Operating Characteristic (ROC) curve. However, this does not in itself provide clinical utility but reflects a statistical association in any given population between one or more variables and clinical outcome. It is not currently established how to incorporate and integrate biofluid-based biomarker data into patient management because there is no standardized role for such data in clinical decision making. We review the current status of biomarker research and discuss how we can integrate existing markers into current clinical practice and what additional biomarkers do we need to improve diagnoses and to guide therapy and to assess treatment efficacy. Furthermore, we argue for employing machine learning (ML) capabilities to integrate the protein biomarker data with other established, routinely used clinical diagnostic tools, to provide the clinician with actionable information to guide medical intervention.

Hypotension during transsphenoidal pituitary surgery associated with increase in plasma levels of brain injury markers

BACKGROUND

Patients undergoing pituitary surgery may experience short- and long-term postoperative morbidity. Intraoperative factors such as hypotension might be a contributing factor. Our aim was to investigate the association between intraoperative hypotension and postoperative plasma levels of tau, neurofilament light (NfL), and glial fibrillary acidic protein (GFAP) as markers of perioperative brain injury.

METHODS

Between June 2016 and October 2017, 35 patients from the Gothenburg Pituitary Tumor Study were included. For tau, NfL, and GFAP, concentrations were measured in plasma samples collected before and immediately following surgery, and on postoperative days 1 and 5. The difference between the highest postoperative value and the value before surgery was used for analysis (∆taupeak , ∆NfLpeak , ∆GFAPpeak ). Intraoperative hypotension was defined as the area under the curve of an absolute threshold below 70 mmHg (AUC70) and a relative threshold below 20% (AUC20%) of the baseline mean arterial blood pressure.

RESULTS

Plasma tau and GFAP were highest immediately following surgery and on day 1, while NfL was highest on day 5. There was a positive correlation between AUC20% and both ∆taupeak (r2  = .20, p < .001) and ∆NfLpeak (r2  = .26, p < .001). No association was found between AUC20% and GFAP or between AUC70 and ∆taupeak , ∆NfLpeak or ∆GFAPpeak .

CONCLUSION

Intraoperative relative, but not absolute, hypotension was associated with increased postoperative plasma tau and NfL concentrations. Patients undergoing pituitary surgery may be vulnerable to relative hypotension, but this needs to be validated in future prospective studies.

Maximizing the Clinical Value of Blood-Based Biomarkers for Mild Traumatic Brain Injury

Mild traumatic brain injury (TBI) and concussion can have serious consequences that develop over time with unpredictable levels of recovery. Millions of concussions occur yearly, and a substantial number result in lingering symptoms, loss of productivity, and lower quality of life. The diagnosis may not be made for multiple reasons, including due to patient hesitancy to undergo neuroimaging and inability of imaging to detect minimal damage. Biomarkers could fill this gap, but the time needed to send blood to a laboratory for analysis made this impractical until point-of-care measurement became available. A handheld blood test is now on the market for diagnosis of concussion based on the specific blood biomarkers glial fibrillary acidic protein (GFAP) and ubiquitin carboxyl terminal hydrolase L1 (UCH-L1). This paper discusses rapid blood biomarker assessment for mild TBI and its implications in improving prediction of TBI course, avoiding repeated head trauma, and its potential role in assessing new therapeutic options. Although we focus on the Abbott i-STAT TBI plasma test because it is the first to be FDA-cleared, our discussion applies to any comparable test systems that may become available in the future. The difficulties in changing emergency department protocols to include new technology are addressed.

Circulating Brain Injury Biomarkers: A Novel Method for Quantification of the Impact on the Brain After Tumor Surgery

BACKGROUND

Clinical methods to quantify brain injury related to neurosurgery are scarce. Circulating brain injury biomarkers have recently gained increased interest as new ultrasensitive measurement techniques have enabled quantification of brain injury through blood sampling.

OBJECTIVE

To establish the time profile of the increase in the circulating brain injury biomarkers glial fibrillary acidic protein (GFAP), tau, and neurofilament light (NfL) after glioma surgery and to explore possible relationships between these biomarkers and outcome regarding volume of ischemic injury identified with postoperative MRI and new neurological deficits.

METHODS

In this prospective study, 34 adult patients scheduled for glioma surgery were included. Plasma concentrations of brain injury biomarkers were measured the day before surgery, immediately after surgery, and on postoperative days 1, 3, 5, and 10.

RESULTS

Circulating brain injury biomarkers displayed a postoperative increase in the levels of GFAP ( P < .001), tau ( P < .001), and NfL ( P < .001) on Day 1 and a later, even higher, peak of NFL at Day 10 ( P = .028). We found a correlation between the increased levels of GFAP, tau, and NfL on Day 1 after surgery and the volume of ischemic brain tissue on postoperative MRI. Patients with new neurological deficits after surgery had higher levels of GFAP and NfL on Day 1 compared with those without new neurological deficits.

CONCLUSION

Measuring circulating brain injury biomarkers could be a useful method for quantification of the impact on the brain after tumor surgery or neurosurgery in general.

Elevated biomarkers of neural injury in older adults following head-down bed rest: links to cardio-postural deconditioning with spaceflight and aging

Introduction

Prolonged physical inactivity with bed rest or spaceflight is associated with cardiovascular and neuromuscular deconditioning; however, its impact on neural integrity of cardio-postural reflexes and possible mitigation with exercise has not been examined. We assessed the association between the physiological deconditioning of bed rest immobilization with neural injury markers and the effects of 60-75 min of daily exercise.

Methods

Data were collected as part of a randomized clinical trial (clinicaltrials.gov identifier: NCT04964999) at the McGill University Medical Centre. Twenty-two 55- to 65-year-old healthy volunteers gave informed consent and took part. Within sex, participants were randomly assigned to exercise (60- to 75-min daily) or control (inactive) groups and spent 14 days in continuous 6° head-down tilt. Neural injury [neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), total tau (t-Tau), myelin basic protein (MBP), brain-derived neurotrophic factor (BDNF), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1)], as well as interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and insulin-like growth factor 1 (IGF-1) biomarkers were measured before, during, and after bed rest. The false discovery rate with Huber M-estimation was used to correlate changes in biomarkers with cardiovascular and muscular function changes over bed rest.

Results

Bed rest elevated NfL, GFAP, TNF-α, and IL-6 in all participants and reduced IGF-1 in females only. With standing, changes in heart rate, blood pressure, and lower limb muscle motoneuron activity correlated with changes in TNF-α and BDNF. Baroreflex control, leg muscle maximal voluntary contraction, and postural sway are correlated with GFAP and NfL. Exercise participants had fewer interactions than control participants, but significant correlations still existed, with both groups exhibiting similar reductions in orthostatic tolerance.

Discussion

An hour of daily exercise in older persons otherwise immobilized for 2 weeks did not abate bed rest-induced increases in serum signatures of neural injury or pro-inflammatory markers. Exercise reduced the number of physiological interactions of biomarkers, but significant cardio-postural correlations remained with no protection against post-bed rest orthostatic intolerance. The identification of associations of inflammatory and neural injury biomarkers with changes in cardio-postural physiology and exercise points to biotherapeutic opportunities and improved exercise interventions for astronauts and individuals in bed rest.

Clinical trial registration

https://www.clinicaltrials.gov/search?cond=NCT04964999, identifier: NCT04964999.

Biomarkers of traumatic brain injury in vitreous humor: A pilot study

BACKGROUND

Traumatic brain injury (TBI) is one of the major causes of morbidity and mortality worldwide. The patients' and injuries' heterogeneity associated with TBI, alongside with its variable clinical manifestations, make it challenging to make diagnosis and predict prognosis. Therefore, the identification of reliable prognostic markers would be relevant both to support clinical decision-making and forensic evaluation of polytraumatic deaths and cases of medical malpractice. This pilot study aimed to evaluate some of the main biomarkers specific for brain damage in sTBI and mmTBI deaths in samples of vitreous humor (VH) in order to verify whether predictors of prognosis in TBI can be found in this matrix.

METHODS

VH were obtained from both eyes (right and left) of 30 cadavers (20 sTBI and 10 mmTBI) and analysed. These factors were evaluated: NSE (neuron-specific enolase), S100 calcium-binding protein (S100), glial fibrillary acidic protein (GFAP), Brain-derived neurotrophic factor (BDNF), Copeptin, Interleukin 6 (IL-6), Ferritin, Lactate dehydrogenase (LDH), C-Reactive Protein (CRP), Procalcitonin (PCT), Glucose and Neutrophil gelatinase-associated lipocalin (N-Gal).

RESULTS

Four of the analysed proteins (LDH, ferritin, S100 and NSE) proved to be particularly promising. In particular, logistic regression analysis found a good discriminatory power.

CONCLUSIONS

Given the peculiarity of the matrix and the poor standardization of the sampling, such promising results need to be furtherly investigated in serum before being implemented in the forensic practice.

Biomarkers in 5q-associated spinal muscular atrophy-a narrative review

5q-associated spinal muscular atrophy (SMA) is a rare genetic disease caused by mutations in the SMN1 gene, resulting in a loss of functional SMN protein and consecutive degeneration of motor neurons in the ventral horn. The disease is clinically characterized by proximal paralysis and secondary skeletal muscle atrophy. New disease-modifying drugs driving SMN gene expression have been developed in the past decade and have revolutionized SMA treatment. The rise of treatment options led to a concomitant need of biomarkers for therapeutic guidance and an improved disease monitoring. Intensive efforts have been undertaken to develop suitable markers, and numerous candidate biomarkers for diagnostic, prognostic, and predictive values have been identified. The most promising markers include appliance-based measures such as electrophysiological and imaging-based indices as well as molecular markers including SMN-related proteins and markers of neurodegeneration and skeletal muscle integrity. However, none of the proposed biomarkers have been validated for the clinical routine yet. In this narrative review, we discuss the most promising candidate biomarkers for SMA and expand the discussion by addressing the largely unfolded potential of muscle integrity markers, especially in the context of upcoming muscle-targeting therapies. While the discussed candidate biomarkers hold potential as either diagnostic (e.g., SMN-related biomarkers), prognostic (e.g., markers of neurodegeneration, imaging-based markers), predictive (e.g., electrophysiological markers) or response markers (e.g., muscle integrity markers), no single measure seems to be suitable to cover all biomarker categories. Hence, a combination of different biomarkers and clinical assessments appears to be the most expedient solution at the time.

Plasma ubiquitin C-terminal hydrolase-L1 (UCH-L1) level as a blood biomarker of neurological damage after allogeneic hematopoietic cell transplantation

Several biofluid-based biomarkers for traumatic brain injury show promise for use in diagnosis and outcome prediction. In contrast, few studies have investigated biomarkers for non-traumatic brain injury. We focused on ubiquitin C-terminal hydrolase-L1 (UCH-L1), which has been proposed as a screening tool for traumatic brain injury, and investigated whether the plasma UCH-L1 level could also be a useful biomarker in patients with non-traumatic brain injury. We measured UCH-L1 in 25 patients who had experienced neurological complications after allogeneic hematopoietic cell transplantation (HCT) and 22 control patients without any complications or graft-versus-host disease. Although UCH-L1 levels before HCT did not differ significantly (P = 0.053), levels after HCT were higher in patients with neurological complications compared with the control group (P < 0.001). At a UCH-L1 cutoff value of 0.072 ng/ml, sensitivity was 68.0% and specificity was 100%. The statistical power of UCH-L1 for neurological complications seemed to be higher than that of CT and comparable to that of MRI. Thus, increased levels of UCH-L1 might reflect the presence of neurological damage even in patients with non-traumatic brain injury. Further large cohort investigations are warranted.

Inflammation biomarkers IL‑6 and IL‑10 may improve the diagnostic and prognostic accuracy of currently authorized traumatic brain injury tools

Traumatic brain injury (TBI) is currently one of the leading causes of mortality and disability worldwide. At present, no reliable inflammatory or specific molecular neurobiomarker exists in any of the standard models proposed for TBI classification or prognostication. Therefore, the present study was designed to assess the value of a group of inflammatory mediators for evaluating acute TBI, in combination with clinical, laboratory and radiological indices and prognostic clinical scales. In the present single-centre, prospective observational study, 109 adult patients with TBI, 20 adult healthy controls and a pilot group of 17 paediatric patients with TBI from a Neurosurgical Department and two intensive care units of University General Hospital of Heraklion, Greece were recruited. Blood measurements using the ELISA method, of cytokines IL-6, IL-8 and IL-10, ubiquitin C-terminal hydrolase L1 (UCH-L1) and glial fibrillary acidic protein, were performed. Compared with those in healthy control individuals, elevated IL-6 and IL-10 but reduced levels of IL-8 were found on day 1 in adult patients with TBI. In terms of TBI severity classifications, higher levels of IL-6 (P=0.001) and IL-10 (P=0.009) on day 1 in the adult group were found to be associated with more severe TBI according to widely used clinical and functional scales. Moreover, elevated IL-6 and IL-10 in adults were found to be associated with more serious brain imaging findings (rs<0.442; P<0.007). Subsequent multivariate logistic regression analysis in adults revealed that early-measured (day 1) IL-6 [odds ratio (OR)=0.987; P=0.025] and UCH-L1 (OR=0.993; P=0.032) are significant independent predictors of an unfavourable outcome. In conclusion, results from the present study suggest that inflammatory molecular biomarkers may prove to be valuable diagnostic and prognostic tools for TBI.

Association Between Serum Neurofilament Light and Glial Fibrillary Acidic Protein Levels and Head Impact Burden in Women's Collegiate Water Polo

Recent investigations have identified water polo athletes as at risk for concussions and repetitive subconcussive head impacts. Head impact exposure in collegiate varsity women's water polo, however, has not yet been longitudinally quantified. We aimed to determine the relationship between cumulative and acute head impact exposure across pre-season training and changes in serum biomarkers of brain injury. Twenty-two Division I collegiate women's water polo players were included in this prospective observational study. They wore sensor-installed mouthguards during all practices and scrimmages during eight weeks of pre-season training. Serum samples were collected at six time points (at baseline, before and after scrimmages during weeks 4 and 7, and after the eight-week pre-season training period) and assayed for neurofilament light (NfL) and glial fibrillary acidic protein (GFAP) using Simoa® Human Neurology 2-Plex B assay kits. Serum GFAP increased over time (e.g., an increase of 0.6559 pg/mL per week; p = 0.0087). Neither longitudinal nor acute pre-post scrimmage changes in GFAP, however, were associated with head impact exposure. Contrarily, an increase in serum NfL across the study period was associated with cumulative head impact magnitude (sum of peak linear acceleration: B = 0.015, SE = 0.006, p = 0.016; sum of peak rotational acceleration: B = 0.148, SE = 0.048, p = 0.006). Acute changes in serum NfL were not associated with head impacts recorded during the two selected scrimmages. Hormonal contraceptive use was associated with lower serum NfL and GFAP levels over time, and elevated salivary levels of progesterone were also associated with lower serum NfL levels. These results suggest that detecting increases in serum NfL may be a useful way to monitor cumulative head impact burden in women's contact sports and that female-specific factors, such as hormonal contraceptive use and circulating progesterone levels, may be neuroprotective, warranting further investigations.

Effects of early adjunctive pharmacotherapy on serum levels of brain injury biomarkers in patients with traumatic brain injury: a systematic review of randomized controlled studies

Objectives: Traumatic brain injury (TBI) is one of the top causes of morbidity and mortality worldwide. The review aimed to discuss and summarize the current evidence on the effectiveness of adjuvant neuroprotective treatments in terms of their effect on brain injury biomarkers in TBI patients. Methods: To identify relevant studies, four scholarly databases, including PubMed, Cochrane, Scopus, and Google Scholar, were systematically searched using predefined search terms. English-language randomized controlled clinical trials reporting changes in brain injury biomarkers, namely, neuron-specific enolase (NSE), glial fibrillary acid protein (GFAP), ubiquitin carboxyl-terminal esterase L1 (UCHL₁) and/or S100 beta (S100 ß), were included. The methodological quality of the included studies was assessed using the Cochrane risk-of-bias tool. Results: A total of eleven studies with eight different therapeutic options were investigated; of them, tetracyclines, metformin, and memantine were discovered to be promising choices that could improve neurological outcomes in TBI patients. The most utilized serum biomarkers were NSE and S100 ß followed by GFAP, while none of the included studies quantified UCHL₁. The heterogeneity in injury severity categories and measurement timing may affect the overall evaluation of the clinical efficacy of potential therapies. Therefore, unified measurement protocols are highly warranted to inform clinical decisions. Conclusion: Few therapeutic options showed promising results as an adjuvant to standard care in patients with TBI. Several considerations for future work must be directed towards standardizing monitoring biomarkers. Investigating the pharmacotherapy effectiveness using a multimodal biomarker panel is needed. Finally, employing stratified randomization in future clinical trials concerning potential confounders, including age, trauma severity levels, and type, is crucial to inform clinical decisions. Clinical Trial Registration: [https://www.crd.york.ac.uk/prospero/dis], identifier [CRD42022316327].

Acute Blood Levels of Neurofilament Light Indicate One-Year White Matter Pathology and Functional Impairment in Repetitive Mild Traumatic Brain Injured Mice

Mild traumatic brain injury (mTBI) mostly causes transient symptoms, but repeated (r)mTBI can lead to neurodegenerative processes. Diagnostic tools to evaluate the presence of ongoing occult neuropathology are lacking. In a mouse model of rmTBI, we investigated MRI and plasma biomarkers of brain damage before chronic functional impairment arose. Anesthetized adult male and female C57BL/6J mice were subjected to rmTBI or a sham procedure. Sensorimotor deficits were evaluated up to 12 months post-injury in SNAP and Neuroscore tests. Cognitive function was assessed in the novel object recognition test at six and 12 months. Diffusion tensor imaging (DTI) and structural magnetic resonance imaging (MRI) were performed at six and 12 months to examine white matter and structural damage. Plasma levels of neurofilament light (NfL) were assessed longitudinally up to 12 months. Brain histopathology was performed at 12 months. Independent groups of mice were used to examine the effects of 2-, 7- and 14-days inter-injury intervals on acute plasma NfL levels and on hyperactivity. Twelve months after an acute transient impairment, sensorimotor functions declined again in rmTBI mice (p < 0.001 vs sham), but not earlier. Similarly, rmTBI mice showed memory impairment at 12 (p < 0.01 vs sham) but not at 6 months. White matter damage examined by DTI was evident in rmTBI mice at both six and 12 months (p < 0.001 vs sham). This was associated with callosal atrophy (p < 0.001 vs sham) evaluated by structural MRI. Plasma NfL at one week was elevated in rmTBI (p < 0.001 vs sham), and its level correlated with callosal atrophy at 12 months (Pearson r = 0.72, p < 0.01). Histopathology showed thinning of the corpus callosum and marked astrogliosis in rmTBI mice. The NfL levels were higher in mice subjected to short (2 days) compared with longer (7 and 14 days) inter-injury intervals (p < 0.05), and this correlated with hyperactivity in mice (Pearson r = 0.50; p < 0.05). These findings show that rmTBI causes white matter pathology detectable by MRI before chronic functional impairment. Early quantification of plasma NfL correlates with the degree of white matter atrophy one year after rmTBI and can serve to monitor the brain's susceptibility to a second mTBI, supporting its potential clinical application to guide the return to practice in sport-related TBI.

Acute intranasal treatment with nerve growth factor limits the onset of traumatic brain injury in young rats

BACKGROUND AND PURPOSE

Traumatic brain injury (TBI) comprises a primary injury directly induced by impact, which progresses into a secondary injury leading to neuroinflammation, reactive astrogliosis, and cognitive and motor damage. To date, treatment of TBI consists solely of palliative therapies that do not prevent and/or limit the outcomes of secondary damage and only stabilize the deficits. The neurotrophin, nerve growth factor (NGF), delivered to the brain parenchyma following intranasal application, could be a useful means of limiting or improving the outcomes of the secondary injury, as suggested by pre-clinical and clinical data.

EXPERIMENTAL APPROACH

We evaluated the effect of acute intranasal treatment of young (20-postnatal day) rats, with NGF in a TBI model (weight drop/close head), aggravated by hypoxic complications. Immediately after the trauma, rats were intranasally treated with human recombinant NGF (50 μg·kg^-1 ), and motor behavioural test, morphometric and biochemical assays were carried out 24 h later.

KEY RESULTS

Acute intranasal NGF prevented the onset of TBI-induced motor disabilities, and decreased reactive astrogliosis, microglial activation and IL-1β content, which after TBI develops to the same extent in the impact zone and the hypothalamus.

CONCLUSION AND IMPLICATIONS

Intranasal application of NGF was effective in decreasing the motor dysfunction and neuroinflammation in the brain of young rats in our model of TBI. This work forms an initial pre-clinical evaluation of the potential of early intranasal NGF treatment in preventing and limiting the disabling outcomes of TBI, a clinical condition that remains one of the unsolved problems of paediatric neurology.

Neurologic Biomarkers, Neuroimaging, and Cognitive Function in Persistent Atrial Fibrillation: A Cross-Sectional Study

The aim of this study was to evaluate the specific neurologic biomarkers, neuroimaging findings, and cognitive function in patients with persistent atrial fibrillation (AF) undergoing electrical cardioversion, compared to control subjects. This cross-sectional study included 25 patients with persistent AF undergoing electrical cardioversion and 16 age- and sex-matched control subjects. Plasma levels of glial fibrillary acidic protein (GFAP), neurofilament light protein (NFL), and ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1), as well as parameters of neuroimaging and cognitive function, were compared between the groups. Neuroimaging was performed using the standard magnetic resonance imaging (MRI) protocol. Cognitive function was assessed using the Patient-Reported Outcomes Measurement Information System (PROMIS) Cognitive Function Index. Further analysis of neurologic biomarkers was performed based on the subsequent electrical cardioversion. There was no significant difference in GFAP (median of 24.7 vs. 28.7 pg/mL, p = 0.347), UCH-L1 (median of 112.8 vs. 117.7 pg/mL, p = 0.885), and NFL (median of 14.2 vs. 15.4 pg/mL, p = 0.886) levels between AF patients and control subjects. Similarly, neuroimaging showed no between-group difference in large cortical and non-cortical lesions (n = 2, 8.0% vs. n = 0, 0.0%, p = 0.246), small non-cortical lesions (n = 5, 20.0% vs. n = 5, 31.3%, p = 0.413), white matter hyperintensity (n = 23, 92.0% vs. n = 14, 87.5%, p = 0.636), and thromboembolic lesions (n = 0, 0.0% vs. n = 1, 6.3%, p = 0.206). Cognitive assessment did not show any between-group difference in the PROMIS index (52.2 ± 9.6 vs. 51.2 ± 6.2, p = 0.706). Finally, there were no significant dynamics in neurologic biomarkers following electrical cardioversion (p > 0.05). This hypothesis-generating study did not find a significant difference in neurologic biomarkers, neuroimaging findings, or cognitive function between patients with persistent AF and controls. The restoration of sinus rhythm was not significantly associated with a change in neurologic biomarkers. Further powered longitudinal studies are needed to re-assess these findings in an AF population.

Time-Dependent Changes in the Biofluid Levels of Neural Injury Markers in Severe Traumatic Brain Injury Patients-Cerebrospinal Fluid and Cerebral Microdialysates: A Longitudinal Prospective Pilot Study

Monitoring protein biomarker levels in the cerebrospinal fluid (CSF) can help assess injury severity and outcome after traumatic brain injury (TBI). Determining injury-induced changes in the proteome of brain extracellular fluid (bECF) can more closely reflect changes in the brain parenchyma, but bECF is not routinely available. The aim of this pilot study was to compare time-dependent changes of S100 calcium-binding protein B (S100B), neuron-specific enolase (NSE), total Tau, and phosphorylated Tau (p-Tau) levels in matching CSF and bECF samples collected at 1, 3, and 5 days post-injury from severe TBI patients (n = 7; GCS 3-8) using microcapillary-based western analysis. We found that time-dependent changes in CSF and bECF levels were most pronounced for S100B and NSE, but there was substantial patient-to-patient variability. Importantly, the temporal pattern of biomarker changes in CSF and bECF samples showed similar trends. We also detected two different immunoreactive forms of S100B in both CSF and bECF samples, but the contribution of the different immunoreactive forms to total immunoreactivity varied from patient to patient and time point to time point. Our study is limited, but it illustrates the value of both quantitative and qualitative analysis of protein biomarkers and the importance of serial sampling for biofluid analysis after severe TBI.

Neurological symptoms and neuronal damage markers in acute COVID-19: Is there a correlation? A pilot study

A wide spectrum of neurological symptoms (NS) has been described in patients with COVID-19. We examined the plasma levels of neuron-specific enolase (NSE) and neurofilament light chain (NFL) together, as neuronal damage markers, and their relationships with clinical severity in patients with NS at acute COVID-19. A total of 20 healthy controls and 59 patients with confirmed COVID-19 were enrolled in this pilot prospective study. Serum NSE and NFL levels were measured by using the enzyme-linked immunoassay method from serum samples. Serum NSE levels were found to be significantly higher in the severe group than in the nonsevere group (p = 0.034). However, serum NFL levels were similar between the control and disease groups (p > 0.05). For the mild group, serum NFL levels were significantly higher in patients with the sampling time ≥5 days than in those with the sampling time <5 days (p = 0.019). However, no significant results for NSE and NFL were obtained in patients with either single or multiple NS across the groups (p > 0.05). Increased serum NSE levels were associated with disease severity regardless of accompanied NS in patients with acute COVID-19 infection. However, serum NFL levels may have a role at the subacute phase of COVID-19.

Serum Glial Fibrillary Acidic Protein in Detecting Intracranial Injuries Following Minor Head Trauma; a Systematic Review and Meta-Analysis

Introduction

Developing novel diagnostic and screening tools for exploring intracranial injuries following minor head trauma is a necessity. This study aimed to evaluate the diagnostic value of serum glial fibrillary acidic protein (GFAP) in detecting intracranial injuries following minor head trauma.

Methods

An extensive search was performed in Medline, Embase, Scopus, and Web of Science databases up to the end of April 2022. Human observational studies were chosen, regardless of sex and ethnicity of their participants. Pediatrics studies, report of diagnostic value of GFAP combined with other biomarkers (without reporting the GFAP alone), articles including patients with all trauma severity, defining minor head trauma without intracranial lesions as the outcome of the study, not reporting sensitivity/specificity or any other values essential for computation of true positive, true negative, false positive and false-negative, being performed in the prehospital setting, assessing the prognostic value of GFAP, duplicated reports, preclinical studies, retracted articles, and review papers were excluded. The result was provided as pooled sensitivity, specificity, diagnostic score and diagnostic odds ratio, and area under the summary receiver operating characteristic (SROC) curve with a 95% confidence interval (95% CI).

Results

Eventually, 11 related articles were introduced into the meta-analysis. The pooled analysis implies that the area under the SROC curve for serum GFAP level in minor traumatic brain injuries (TBI) was 0.75 (95% CI: 0.71 to 0.78). Sensitivity and specificity of this biomarker in below 100 pg/ml cut-off were 0.83 (95% CI: 0.78 to 0.89) and 0.39 (95% CI: 0.24 to 0.53), respectively. The diagnostic score and diagnostic odds ratio of GFAP in detection of minor TBI were 1.13 (95% CI: 0.53 to 1.74) and 3.11 (95% CI: 1.69 to 5.72), respectively. The level of evidence for the presented results were moderate.

Conclusion

The present study's findings demonstrate that serum GFAP can detect intracranial lesions in mild TBI patients. The optimum cut-off of GFAP in detection of TBI was below 100 pg/ml. As a result, implementing serum GFAP may be beneficial in mild TBI diagnosis for preventing unnecessary computed tomography (CT) scans and their related side effects.

Glial fibrillary acidic protein as a biomarker in neuromyelitis optica spectrum disorder: a current review

INTRODUCTION

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing, often debilitating neuroinflammatory disease, whose predominant clinical manifestations are longitudinally extensive transverse myelitis and optic neuritis. About 80% of the patients with an NMOSD phenotype have pathogenic autoantibodies against the astrocyte water channel aquaporin-4 (AQP4-IgG). While therapeutic options for NMOSD have greatly expanded in recent years, well-established biomarkers for prognosis or treatment response are still lacking. Glial fibrillary acidic protein (GFAP) is mainly expressed in astrocytes and can be detected in cerebrospinal fluid (CSF) and blood of patients with NMOSD.

AREAS COVERED

Here, we comprehensively review the current knowledge on GFAP as a biomarker in NMOSD.

EXPERT OPINION

In patients with AQP4-IgG⁺ NMOSD, GFAP levels are elevated in CSF and serum during acute attacks and correlate with disability, consistent with the pathophysiology of this antibody-mediated astrocytopathy. Serum GFAP levels tend to be higher in AQP4-IgG⁺ NMOSD than in its differential diagnoses, multiple sclerosis, and myelin oligodendrocyte antibody-associated disease. Importantly, serum GFAP levels in AQP4-IgG⁺ NMOSD during remission may be predictive of future disease activity. Serial serum GFAP measurements are emerging as a biomarker to monitor disease activity in AQP4-IgG⁺ NMOSD and could have the potential for application in clinical practice.

C. AK, Singh D, Subberwal M. Clinical utility of serum glial fibrillary acidic protein in glial neoplasm

Background

Glial fibrillary acidic protein (GFAP) is a member of the cytoskeletal protein family and is widely expressed in astroglial and neural stem cells, also in glial tumors such as astrocytoma and Glioblastoma (GBM). Increased GFAP expression and disruption of the blood-brain barrier are the characteristic features of GBM. Higher serum GFAP levels can help differentiate GBM from GBM mimics (such as primary central nervous system lymphoma, metastasis, or demyelinating lesions).

Methods

This prospective study was carried out in a tertiary care center in the department of neurosurgery on newly diagnosed glioma patients who underwent surgery from January 2018 to July 2019, excluded patients with history of the previous surgery for glioma, traumatic brain injury, and ischemic or hemorrhagic stroke. The blood sample was obtained at admission before undergoing invasive procedure. Pathological examination of the tumor biopsy sample was carried out using classical hematoxylin-eosin and immunohistochemical staining. All statistical analyses were performed using SPSS version 24.0.

Results

The mean preoperative tumor volume was 40 cm³ (range 17.19-65.57 cm³; standard deviation [SD] = 9.99 cm³) which showed 98.25% mean reduction in volume postsurgery (mean tumor volume = 0.7 cm³; SD = 0.19 cm³). Preoperative serum GFAP measurements show higher levels (spearman's rho coefficient = 0.610 with P = 0.000) with increasing grade of tumor. GFAP levels also demonstrated higher value with increasing preoperative tumor volume.

Conclusion

Increasing serum GFAP levels in the preoperative period correlate with higher tumor grade, especially grade III and grade IV tumors. The serum GFAP levels showed relation to tumor volume, both before and after surgery.

Temporal proteomics of human cerebrospinal fluid after severe traumatic brain injury

The pathophysiology of traumatic brain injury (TBI) requires further characterization to fully elucidate changes in molecular pathways. Cerebrospinal fluid (CSF) provides a rich repository of brain-associated proteins. In this retrospective observational study, we implemented high-resolution mass spectrometry to evaluate changes to the CSF proteome after severe TBI. 91 CSF samples were analyzed with mass spectrometry, collected from 16 patients with severe TBI (mean 32 yrs; 81% male) on day 0, 1, 2, 4, 7 and/or 10 post-injury (8-16 samples/timepoint) and compared to CSF obtained from 11 non-injured controls. We quantified 1152 proteins with mass spectrometry, of which approximately 80% were associated with CSF. 1083 proteins were differentially regulated after TBI compared to control samples. The most highly-upregulated proteins at each timepoint included neutrophil elastase, myeloperoxidase, cathepsin G, matrix metalloproteinase-8, and S100 calcium-binding proteins A8, A9 and A12-all proteins involved in neutrophil activation, recruitment, and degranulation. Pathway enrichment analysis confirmed the robust upregulation of proteins associated with innate immune responses. Conversely, downregulated pathways included those involved in nervous system development, and several proteins not previously identified after TBI such as testican-1 and latrophilin-1. We also identified 7 proteins (GM2A, Calsyntenin 1, FAT2, GANAB, Lumican, NPTX1, SFRP2) positively associated with an unfavorable outcome at 6 months post-injury. Together, these findings highlight the robust innate immune response that occurs after severe TBI, supporting future studies to target neutrophil-related processes. In addition, the novel proteins we identified to be differentially regulated by severe TBI warrant further investigation as potential biomarkers of brain damage or therapeutic targets.

Plasma Neurofilament Light Chain (NF-L) Is a Prognostic Biomarker for Cortical Damage Evolution but Not for Cognitive Impairment or Epileptogenesis Following Experimental TBI

Plasma neurofilament light chain (NF-L) levels were assessed as a diagnostic biomarker for traumatic brain injury (TBI) and as a prognostic biomarker for somatomotor recovery, cognitive decline, and epileptogenesis. Rats with severe TBI induced by lateral fluid-percussion injury (n = 26, 13 with and 13 without epilepsy) or sham-operation (n = 8) were studied. During a 6-month follow-up, rats underwent magnetic resonance imaging (MRI) (day (D) 2, D7, and D21), composite neuroscore (D2, D6, and D14), Morris-water maze (D35−D39), and a 1-month-long video-electroencephalogram to detect unprovoked seizures during the 6th month. Plasma NF-L levels were assessed using a single-molecule assay at baseline (i.e., naïve animals) and on D2, D9, and D178 after TBI or a sham operation. Plasma NF-L levels were 483-fold higher on D2 (5072.0 ± 2007.0 pg/mL), 89-fold higher on D9 (930.3 ± 306.4 pg/mL), and 3-fold higher on D176 32.2 ± 8.9 pg/mL after TBI compared with baseline (10.5 ± 2.6 pg/mL; all p < 0.001). Plasma NF-L levels distinguished TBI rats from naïve animals at all time-points examined (area under the curve [AUC] 1.0, p < 0.001), and from sham-operated controls on D2 (AUC 1.0, p < 0.001). Plasma NF-L increases on D2 were associated with somatomotor impairment severity (ρ = −0.480, p < 0.05) and the cortical lesion extent in MRI (ρ = 0.401, p < 0.05). Plasma NF-L increases on D2 or D9 were associated with the cortical lesion extent in histologic sections at 6 months post-injury (ρ = 0.437 for D2; ρ = 0.393 for D9, p < 0.05). Plasma NF-L levels, however, did not predict somatomotor recovery, cognitive decline, or epileptogenesis (p > 0.05). Plasma NF-L levels represent a promising noninvasive translational diagnostic biomarker for acute TBI and a prognostic biomarker for post-injury somatomotor impairment and long-term structural brain damage.