A prospective pilot study on serum cleaved tau protein as a neurological marker in severe traumatic brain injury

Recovery from Traumatic Brain Injury Is Nociceptin/Orphanin FQ Peptide Receptor Genotype-, Sex-, and Injury Severity-Dependent

Traumatic brain injury (TBI) is a leading cause of death and disability in the United States, and survivors often experience mental and physical health consequences that reduce quality of life. We previously reported that blockade of the nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor reduced tissue damage markers produced by blast TBI. The goal of this study was to determine the extent to which N/OFQ and NOP receptor levels change following mild (mTBI) and moderate TBI (modTBI) and whether the absence of the NOP receptor attenuates TBI-induced sequelae. Male and female NOP receptor knockout (KO) or wild-type (WT) rats received craniotomy-only (sham) or craniotomy plus mTBI, or modTBI impact to the left cerebral hemisphere. Neurologic and vestibulomotor deficits and nociceptive hyperalgesia and allodynia found in WT male and female rats following mTBI and modTBI were greatly reduced or absent in NOP receptor KO rats. NOP receptor levels increased in brain tissue from injured males but remained unchanged in females. Neurofilament light chain (NF-L) and glial fibrillary acidic protein (GFAP) expression were reduced in NOP receptor KO rats compared with WT following TBI. Levels of N/OFQ in injured brain tissue correlated with neurobehavioral outcomes and GFAP in WT males, but not with KO male or WT and KO female rats. This study reveals a significant contribution of the N/OFQ-NOP receptor system to TBI-induced deficits and suggests that the NOP receptor should be regarded as a potential therapeutic target for TBI. SIGNIFICANCE STATEMENT: This study revealed that nociceptin/orphanin FQ peptide (NOP) receptor knockout animals experienced fewer traumatic brain injury (TBI)-induced deficits than their wild-type counterparts in a sex- and injury severity-dependent manner, suggesting that NOP receptor antagonists may be a potential therapy for TBI.

Traumatic Brain Injury Induces Nociceptin/Orphanin FQ and Nociceptin Opioid Peptide Receptor Expression within 24 Hours

Traumatic brain injury (TBI) is a major cause of mortality and disability around the world, for which no treatment has been found. Nociceptin/Orphanin FQ (N/OFQ) and the nociceptin opioid peptide (NOP) receptor are rapidly increased in response to fluid percussion, stab injury, and controlled cortical impact (CCI) TBI. TBI-induced upregulation of N/OFQ contributes to cerebrovascular impairment, increased excitotoxicity, and neurobehavioral deficits. Our objective was to identify changes in N/OFQ and NOP receptor peptide, protein, and mRNA relative to the expression of injury markers and extracellular regulated kinase (ERK) 24 h following mild (mTBI) and moderate TBI (ModTBI) in wildtype (WT) and NOP receptor-knockout (KO) rats. N/OFQ was quantified by radioimmunoassay, mRNA expression was assessed using real-time PCR and protein levels were determined by immunoblot analysis. This study revealed increased N/OFQ mRNA and peptide levels in the CSF and ipsilateral tissue of WT, but not KO, rats 24 h post-TBI; NOP receptor mRNA increased after ModTBI. Cofilin-1 activation increased in the brain tissue of WT but not KO rats, ERK activation increased in all rats following ModTBI; no changes in injury marker levels were noted in brain tissue at this time. In conclusion, this study elucidates transcriptional and translational changes in the N/OFQ-NOP receptor system relative to TBI-induced neurological deficits and initiation of signaling cascades that support the investigation of the NOP receptor as a therapeutic target for TBI.

The Nociceptin/Orphanin FQ peptide receptor antagonist, SB-612111, improves cerebral blood flow in a rat model of traumatic brain injury

Traumatic brain injury (TBI) affects more than 2.5 million people in the U.S. each year and is the leading cause of death and disability in children and adults ages 1 to 44. Approximately 90% of TBI cases are classified as mild but may still lead to acute detrimental effects such as impaired cerebral blood flow (CBF) that result in prolonged impacts on brain function and quality of life in up to 15% of patients. We previously reported that nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor antagonism reversed mild blast TBI-induced vestibulomotor deficits and prevented hypoxia. To explore mechanisms by which the NOP receptor-N/OFQ pathway modulates hypoxia and other TBI sequelae, the ability of the NOP antagonist, SB-612111 (SB), to reverse TBI-induced CBF and associated injury marker changes were tested in this study. Male Wistar rats randomly received sham craniotomy or craniotomy + TBI via controlled cortical impact. Injury severity was assessed after 1 h (modified neurological severity score (mNSS). Changes in CBF were assessed 2 h post-injury above the exposed cortex using laser speckle contrast imaging in response to the direct application of increasing concentrations of vehicle or SB (1, 10, and 100 µM) to the brain surface. TBI increased mNSS scores compared to baseline and confirmed mild TBI (mTBI) severity. CBF was significantly impaired on the ipsilateral side of the brain following mTBI, compared to contralateral side and to sham rats. SB dose-dependently improved CBF on the ipsilateral side after mTBI compared to SB effects on the respective ipsilateral side of sham rats but had no effect on contralateral CBF or in uninjured rats. N/OFQ levels increased in the cerebral spinal fluid (CSF) following mTBI, which correlated with the percent decrease in ipsilateral CBF. TBI also activated ERK and cofilin within 3 h post-TBI; ERK activation correlated with increased CSF N/OFQ. In conclusion, this study reveals a significant contribution of the N/OFQ-NOP receptor system to TBI-induced dysregulation of cerebral vasculature and suggests that the NOP receptor should be considered as a potential therapeutic target for TBI.

Blood-Based Biomarkers for Neuroprognostication in Acute Brain Injury

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

Cerebrospinal Fluid and Blood Biomarkers in Patients with Post-Traumatic Disorders of Consciousness: A Scoping Review

(1) Background: Cerebrospinal fluid (CSF) and blood biomarkers are emerging tools used to obtain information on secondary brain damage and to improve diagnostic and prognostic accuracy for patients with prolonged post-traumatic disorders of consciousness (DoC). We synthesized available data from studies evaluating CSF and blood biomarkers in these patients. (2) Methods: A scoping review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews checklist to identify and synthesize data from relevant studies. Studies were identified by PubMed and manual searches. Those involving patients with unresponsive wakefulness syndrome or in a minimally conscious state for >28 days, evaluating CSF or blood biomarkers, and conducted on patients with traumatic brain injuries older than 16 years were included in the review. (3) Results: In total, 17 studies were included. Findings on neurofilament light chain, proteins, metabolites, lipids, amyloid-β, tau, melatonin, thyroid hormones, microtubule-associated protein 2, neuron-specific enolase, and brain-derived neurotrophic factor were included in the qualitative synthesis. (4) Conclusions: The most promising applications for CSF and blood biomarkers are the monitoring of secondary neurodegeneration, support of DoC diagnoses, and refinement of prognoses, although current evidence remains too scarce to recommend such uses of these biomarkers in clinical practice.

Prognosis and Diagnostic Biomarkers of Mild Traumatic Brain Injury: Current Status and Future Prospects

Mild traumatic brain injury (mTBI) is the most prevalent type of TBI (80-90%). It is characterized by a loss consciousness for less than 30 minutes, post-traumatic amnesia for less than 24 hours, and Glasgow Coma Score of 13-15. Accurately diagnosing mTBIs can be a challenge because the majority of these injuries do not show noticeable or visible changes on neuroimaging studies. Appropriate determination of mTBI is tremendously important because it might lead in some cases to post-concussion syndrome, cognitive impairments including attention, memory, and speed of information processing problems. The scientists have studied different methods to improve mTBI diagnosis and enhanced approaches that would accurately determine the severity of the trauma. The present review focuses on discussing the role of biomarkers as potential key factors in diagnosing mTBI. The present review focuses on 1) protein based peripheral and CNS markers, 2) genetic biomarkers, 3) imaging biomarkers, 4) neurophysiological biomarkers, and 5) the studies and clinical trials in mTBI. Each section provides information and characteristics on different biomarkers for mTBI.

Blood Biomarkers and Structural Imaging Correlations Post-Traumatic Brain Injury: A Systematic Review

BACKGROUND

Blood biomarkers are of increasing importance in the diagnosis and assessment of traumatic brain injury (TBI). However, the relationship between them and lesions seen on imaging remains unclear.

OBJECTIVE

To perform a systematic review of the relationship between blood biomarkers and intracranial lesion types, intracranial lesion injury patterns, volume/number of intracranial lesions, and imaging classification systems.

METHODS

We searched Medical Literature Analysis and Retrieval System Online, Excerpta Medica dataBASE, and Cumulative Index to Nursing and Allied Health Literature from inception to May 2021, and the references of included studies were also screened. Heterogeneity in study design, biomarker types, imaging modalities, and analyses inhibited quantitative analysis, with a qualitative synthesis presented.

RESULTS

Fifty-nine papers were included assessing one or more biomarker to imaging comparisons per paper: 30 assessed imaging classifications or injury patterns, 28 assessed lesion type, and 11 assessed lesion volume or number. Biomarker concentrations were associated with the burden of brain injury, as assessed by increasing intracranial lesion volume, increasing numbers of traumatic intracranial lesions, and positive correlations with imaging classification scores. There were inconsistent findings associating different biomarkers with specific imaging phenotypes including diffuse axonal injury, cerebral edema, and intracranial hemorrhage.

CONCLUSION

Blood-based biomarker concentrations after TBI are consistently demonstrated to correlate burden of intracranial disease. The relation with specific injury types is unclear suggesting a lack of diagnostic specificity and/or is the result of the complex and heterogeneous nature of TBI.

Relationship of admission blood proteomic biomarkers levels to lesion type and lesion burden in traumatic brain injury: A CENTER-TBI study

BACKGROUND

We aimed to understand the relationship between serum biomarker concentration and lesion type and volume found on computed tomography (CT) following all severities of TBI.

METHODS

Concentrations of six serum biomarkers (GFAP, NFL, NSE, S100B, t-tau and UCH-L1) were measured in samples obtained <24 hours post-injury from 2869 patients with all severities of TBI, enrolled in the CENTER-TBI prospective cohort study (NCT02210221). Imaging phenotypes were defined as intraparenchymal haemorrhage (IPH), oedema, subdural haematoma (SDH), extradural haematoma (EDH), traumatic subarachnoid haemorrhage (tSAH), diffuse axonal injury (DAI), and intraventricular haemorrhage (IVH). Multivariable polynomial regression was performed to examine the association between biomarker levels and both distinct lesion types and lesion volumes. Hierarchical clustering was used to explore imaging phenotypes; and principal component analysis and k-means clustering of acute biomarker concentrations to explore patterns of biomarker clustering.

FINDINGS

2869 patient were included, 68% (n=1946) male with a median age of 49 years (range 2-96). All severities of TBI (mild, moderate and severe) were included for analysis with majority (n=1946, 68%) having a mild injury (GCS 13-15). Patients with severe diffuse injury (Marshall III/IV) showed significantly higher levels of all measured biomarkers, with the exception of NFL, than patients with focal mass lesions (Marshall grades V/VI). Patients with either DAI+IVH or SDH+IPH+tSAH, had significantly higher biomarker concentrations than patients with EDH. Higher biomarker concentrations were associated with greater volume of IPH (GFAP, S100B, t-tau;adj r2 range:0·48-0·49; p<0·05), oedema (GFAP, NFL, NSE, t-tau, UCH-L1;adj r2 range:0·44-0·44; p<0·01), IVH (S100B;adj r2 range:0.48-0.49; p<0.05), Unsupervised k-means biomarker clustering revealed two clusters explaining 83·9% of variance, with phenotyping characteristics related to clinical injury severity.

INTERPRETATION

Interpretation: Biomarker concentration within 24 hours of TBI is primarily related to severity of injury and intracranial disease burden, rather than pathoanatomical type of injury.

FUNDING

CENTER-TBI is funded by the European Union 7th Framework programme (EC grant 602150).

The Clinical Use of Serum Biomarkers in Traumatic Brain Injury: A Systematic Review Stratified by Injury Severity

BACKGROUND

Serum biomarkers have gained significant popularity as an adjunctive measure in the evaluation and prognostication of traumatic brain injury (TBI). However, a concise and clinically oriented report of the major markers in function of TBI severity is lacking. This systematic review aims to report current data on the diagnostic and prognostic utility of blood-based biomarkers across the spectrum of TBI.

METHODS

A literature search of the PubMed/Medline electronic database was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We excluded systematic reviews and meta-analyses that did not provide novel data. The American College of Cardiology/American Heart Association criteria were used to assess levels of evidence.

RESULTS

An initial 1463 studies were identified. In total, 115 full-text articles reporting on 94 distinct biomarkers met the inclusion criteria. Glasgow Coma Scale scores, computed tomography/magnetic resonance imaging abnormalities, and injury severity scores were the most used clinical diagnostic variables. Glasgow Outcome Scores and 1-, 3-, and 6-month mortality were the most used clinical prognostic variables. Several biomarkers significantly correlated with these variables and had statistically significant different levels in TBI subjects when compared with healthy, orthopedic, and polytrauma controls. The biomarkers also displayed significant variability across mild, moderate, and severe TBI categories, as well as in concussion cases.

CONCLUSIONS

This review summarizes existing high-quality evidence that supports the use of severity-specific biomarkers in the diagnostic and prognostic evaluation of TBI. These data can be used as a launching platform for the validation of upcoming clinical studies.

Systematic Review of Serum Biomarkers in Traumatic Brain Injury

Traumatic brain injury (TBI) is responsible for the majority of trauma-related deaths and is a leading cause of disability. It is characterized by an inflammatory process involved in the progression of secondary brain injury. TBI is measured by the Glasgow Coma Scale (GCS) with scores ranging from 15-3, demonstrating mild to severe brain injury. Apart from this clinical assessment of TBI, compendiums of literature have been published on TBI-related serum markers.Herein we create a comprehensive appraisal of the most prominent serum biomarkers used in the assessment and care of TBI.The PubMed, Scopus, Cochrane, and Web of Science databases were queried with the terms “biomarker” and “traumatic brain injury” as search terms with only full-text, English articles within the past 10 years selected. Non-human studies were excluded, and only adult patients fell within the purview of this analysis. A total of 528 articles were analyzed in the initial search with 289 selected for screening. A further 152 were excluded for primary screening. Of the remaining 137, 54 were included in the final analysis. Serum biomarkers were listed into the following broad categories for ease of discussion: immune markers and markers of inflammation, hormones as biomarkers, coagulation and vasculature, genetic polymorphisms, antioxidants and oxidative stress, apoptosis and degradation pathways, and protein markers. Glial fibrillary acidic protein(GFAP), S100, and neurons specific enolase (NSE) were the most prominent and frequently cited markers. Amongst these three, no single serum biomarker demonstrated neither superior sensitivity nor specificity compared to the other two, therefore noninvasive panels should incorporate these three serum biomarkers to retain sensitivity and maximize specificity for TBI.

The Current State of Traumatic Brain Injury Biomarker Measurement Methods

Traumatic brain injury (TBI) is associated with high rates of morbidity and mortality partially due to the limited tools available for diagnosis and classification. Measuring panels of protein biomarkers released into the bloodstream after injury has been proposed to diagnose TBI, inform treatment decisions, and monitor the progression of the injury. Being able to measure these protein biomarkers at the point-of-care would enable assessment of TBIs from the point-of-injury to the patient's hospital bedside. In this review, we provide a detailed discussion of devices reported in the academic literature and available on the market that have been designed to measure TBI protein biomarkers in various biofluids and contexts. We also assess the challenges associated with TBI biomarker measurement devices and suggest future research directions to encourage translation of these devices to clinical use.

A Serum Protein Biomarker Panel Improves Outcome Prediction in Human Traumatic Brain Injury

Brain-enriched protein biomarkers of tissue fate are being introduced clinically to aid in traumatic brain injury (TBI) management. The aim of this study was to determine how concentrations of six different protein biomarkers, measured in samples collected during the first weeks after TBI, relate to injury severity and outcome. We included neurocritical care TBI patients that were prospectively enrolled from 2007 to 2013, all having one to three blood samples drawn during the first 2 weeks. The biomarkers analyzed were S100 calcium-binding protein B (S100B), neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1), tau, and neurofilament-light (NF-L). Glasgow Outcome Score (GOS) was assessed at 12 months. In total, 172 patients were included. All serum markers were associated with injury severity as classified on computed tomography scans at admission. Almost all biomarkers outperformed other known outcome predictors with higher levels the first 5 days, correlating with unfavorable outcomes, and UCH-L1 (0.260, pseduo-R²) displaying the best discrimination in univariate analyses. After adjusting for acknowledged TBI outcome predictors, GFAP and NF-L added most independent information to predict favorable/unfavorable GOS, improving the model from 0.38 to 0.51 pseudo-R². A correlation matrix indicated substantial covariance, with the strongest correlation between UCH-L1, GFAP, and tau (r = 0.827-0.880). Additionally, the principal component analysis exhibited clustering of UCH-L1 and tau, as well as GFAP, S100B, and NSE, which was separate from NF-L. In summary, a panel of several different protein biomarkers, all associated with injury severity, with different cellular origin and temporal trajectories, improve outcome prediction models.

MicroRNA Signature of Traumatic Brain Injury: From the Biomarker Discovery to the Point-of-Care

Traumatic brain injury (TBI) is a serious problem that causes high morbidity and mortality around the world. Currently, no reliable biomarkers are used to assess the severity and predict the recovery. Many protein biomarkers were extensively studied for diagnosis and prognosis of different TBI severities such as S-100β, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), neurofilament light chain (NFL), cleaved tau protein (C-tau), and ubiquitin C-terminal hydrolase-L1 (UCH-L1). However, none of these candidates is currently used in the clinical practice, due to relatively low sensitivity, for the diagnosis of mild TBI (mTBI) or mild to moderate TBI (MMTBI) patients who are clinically well and do not have a detectable intracranial pathology on the scans. MicroRNAs (miRNAs or miRs) are a class of small endogenous molecular regulators, which showed to be altered in different pathologies, including TBI and for this reason, their potential role in diagnosis, prognosis and therapeutic applications, is explored. Promising miRNAs such as miR-21, miR-16 or let-7i were identified as suitable candidate biomarkers for TBI and can differentiate mild from severe TBI. Also, they might represent new potential therapeutic targets. Identification of miRNA signature in tissue or biofluids, for several pathological conditions, is now possible thanks to the introduction of new high-throughput technologies such as microarray platform, Nanostring technologies or Next Generation Sequencing. This review has the aim to describe the role of microRNA in TBI and to explore the most commonly used techniques to identify microRNA profile. Understanding the strengths and limitations of the different methods can aid in the practical use of miRNA profiling for diverse clinical applications, including the development of a point-of-care device.

An update on diagnostic and prognostic biomarkers for traumatic brain injury

INTRODUCTION

Traumatic brain injury (TBI) is a major worldwide neurological disorder of epidemic proportions. To date, there are still no FDA-approved therapies to treat any forms of TBI. Encouragingly, there are emerging data showing that biofluid-based TBI biomarker tests have the potential to diagnose the presence of TBI of different severities including concussion, and to predict outcome. Areas covered: The authors provide an update on the current knowledge of TBI biomarkers, including protein biomarkers for neuronal cell body injury (UCH-L1, NSE), astroglial injury (GFAP, S100B), neuronal cell death (αII-spectrin breakdown products), axonal injury (NF proteins), white matter injury (MBP), post-injury neurodegeneration (total Tau and phospho-Tau), post-injury autoimmune response (brain antigen-targeting autoantibodies), and other emerging non-protein biomarkers. The authors discuss biomarker evidence in TBI diagnosis, outcome prognosis and possible identification of post-TBI neurodegernative diseases (e.g. chronic traumatic encephalopathy and Alzheimer's disease), and as theranostic tools in pre-clinical and clinical settings. Expert commentary: A spectrum of biomarkers is now at or near the stage of formal clinical validation of their diagnostic and prognostic utilities in the management of TBI of varied severities including concussions. TBI biomarkers could serve as a theranostic tool in facilitating drug development and treatment monitoring.