The Prognostic Role of Candidate Serum Biomarkers in the Post-Acute and Chronic Phases of Disorder of Consciousness: A Preliminary Study.

INTRODUCTION: Serum biomarkers, such as Neurofilament Light (NF-L), Glial Fibrillary Acidic Protein (GFAP), Ubiquitin C-terminal Hydrolase (UCH-L1), and Total-tau (T-Tau) have been proposed for outcome prediction in the acute phase of severe traumatic brain injury, but they have been less investigated in patients with prolonged DoC (p-DoC). METHODS: We enrolled 25 p-DoC patients according to the Coma Recovery Scale-Revised (CRS-R). We identified different time points: injury onset (t0), first blood sampling at admission in Neurorehabilitation (t1), and second blood sampling at discharge (t2). Patients were split into improved (improved level of consciousness from t1 to t2) and not-improved (unchanged or worsened level of consciousness from t1 to t2). RESULTS: All biomarker levels decreased over time, even though each biomarker reveals typical features. Serum GFAP showed a weak correlation between t1 and t2 (p = 0.001), while no correlation was observed for serum NF-L (p = 0.955), UCH-L1 (p = 0.693), and T-Tau (p = 0.535) between t1 and t2. Improved patients showed a significant decrease in the level of NF-L (p = 0.0001), UCH-L1 (p = 0.001), and T-Tau (p = 0.002), but not for serum GFAP (p = 0.283). No significant statistical differences were observed in the not-improved group. CONCLUSIONS: A significant correlation was found between the level of consciousness improvement and decreased NF-L, UCH-L1, and T-Tau levels. Future studies on the association of serum biomarkers with neurophysiological and neuroimaging prognostic indicators are recommended.

Association between Cerebrospinal Fluid and Serum Biomarker Levels and Diagnosis, Injury Severity, and Short-Term Outcomes in Patients with Acute Traumatic Spinal Cord Injury.

Acute traumatic spinal cord injury (SCI) is recognized as a global problem that can lead to a range of acute and secondary complications impacting morbidity and mortality. There is still a lack of reliable diagnostic and prognostic biomarkers in patients with SCI that could help guide clinical care and identify novel therapeutic targets for future drug discovery. The aim of this prospective controlled study was to determine the cerebral spinal fluid (CSF) and serum profiles of 10 biomarkers as indicators of SCI diagnosis, severity, and prognosis to aid in assessing appropriate treatment modalities. CSF and serum samples of 15 SCI and ten healthy participants were included in the study. The neurological assessments were scored on admission and at discharge from the hospital using the American Spinal Injury Association Impairment Score (AIS) grades. The CSF and serum concentrations of SBDP150, S100B, GFAP, NF-L, UCHL-1, Tau, and IL-6 were significantly higher in SCI patients when compared with the control group. The CSF GBDP 38/44K, UCHL-L1, S100B, GFAP, and Tau levels were significantly higher in the AIS A patients. This study demonstrated a strong correlation between biomarker levels in the diagnosis and injury severity of SCI but no association with short-term outcomes. Future prospective controlled studies need to be done to support the results of this study.

Comparing blood biomarkers to clinical decision rules to select patients suspected of traumatic brain injury for head computed tomography.

INTRODUCTION: Traumatic brain injury (TBI) is a major public health concern in the U.S. Recommendations for patients admitted in the emergency department (ED) to receive head computed tomography (CT) scan are currently guided by various clinical decision rules. OBJECTIVE: To compare how a blood biomarker approach compares with clinical decision rules in terms of predicting a positive head CT in adult patients suspected of TBI. METHODS: We retrospectively identified patients transported to our emergency department and underwent a noncontrast head CT due to suspicion of TBI and who had blood samples available. Published thresholds for serum and plasma glial fibrillary acidic protein (GFAP), ubiquitin carboxyl-terminal hydrolase-L1 (UCH-L1), and serum S100ß were used to make CT recommendations. These blood biomarker-based recommendations were compared to those achieved under widely used clinical head CT decision rules (Canadian, New Orleans, NEXUS II, and ACEP Clinical Policy). RESULTS: Our study included 463 patients, of which 122 (26.3%) had one or more abnormalities presenting on head CT. Individual blood biomarkers achieved high negative predictive value (NPV) for abnormal head CT findings (88%-98%), although positive predictive value (PPV) was consistently low (25%-42%). A composite biomarker-based decision rule (GFAP+UCH-L1)'s NPV of 100% and PPV of 29% were comparable or better than those achieved under the clinical decision rules. CONCLUSION: Blood biomarkers perform at least as well as clinical rules in terms of selecting TBI patients for head CT and may be easier to implement in the clinical setting. A prospective study is necessary to validate this approach.

Association between Blood and Computed Tomographic Imaging Biomarkers in a Cohort of Mild Traumatic Brain Injury Patients.

The objective of this work was to analyze the relationships between traumatic brain injury (TBI) on computed tomographic (CT) imaging and blood concentration of glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCH-L1), and S100B. This prospective cohort study involved 644 TBI patients referred to Stanford Hospital's Emergency Department between November 2015 and April 2017. Plasma and serum samples of 462 patients were analyzed for levels of GFAP, UCH-L1, and S100B. Glial neuronal ratio (GNR) was calculated as the ratio between GFAP and UCH-L1 concentrations. Admission head CT scans were reviewed for TBI imaging common data elements, and performance of biomarkers for identifying TBI was assessed via area under the receiver operating characteristic curve (ROC). We also dichotomized biomarkers at established thresholds and estimated standard measures of classification accuracy. We assessed the ability of GFAP, UCH-L1, and GNR to discriminate small and large/diffuse lesions based on CT imaging using an ROC analysis. In our cohort of mostly mild TBI patients, GFAP was significantly more accurate in detecting all types of acute brain injuries than UCH-L1 in terms of area under the curve (AUC) values (p < 0.001), and also compared with S100B (p < 0.001). UCH-L1 and S100B had similar performance (comparable AUC values, p = 0.342). Sensitivity exceeded 0.8 for each biomarker across all different types of TBI injuries, and no significant differences were observed by type of injury. There was a significant difference between GFAP and GNR in distinguishing between small lesions and large/diffuse lesions in all injuries (p = 0.004, p = 0.007). In conclusion, GFAP, UCH-L1, and S100B show high sensitivity and negative predictive values for all types of TBI lesions on head CT. A combination of negative blood biomarkers (GFAP and UCH-L1) in a patient suspected of TBI may be used to safely obviate the need for a head CT scan. GFAP is a promising indicator to discriminate between small and large/diffuse TBI lesions.

Predicting Clinical Outcomes 7-10 Years after Severe Traumatic Brain Injury: Exploring the Prognostic Utility of the IMPACT Lab Model and Cerebrospinal Fluid UCH-L1 and MAP-2.

BACKGROUND: Severe traumatic brain injury (TBI) is a major contributor to disability and mortality in the industrialized world. Outcomes of severe TBI are profoundly heterogeneous, complicating outcome prognostication. Several prognostic models have been validated for acute prediction of 6-month global outcomes following TBI (e.g., morbidity/mortality). In this preliminary observational prognostic study, we assess the utility of the International Mission on Prognosis and Analysis of Clinical Trials in TBI (IMPACT) Lab model in predicting longer term global and cognitive outcomes (7-10 years post injury) and the extent to which cerebrospinal fluid (CSF) biomarkers enhance outcome prediction. METHODS: Very long-term global outcome was assessed in a total of 59 participants (41 of whom did not survive their injuries) using the Glasgow Outcome Scale-Extended and Disability Rating Scale. More detailed outcome information regarding cognitive functioning in daily life was collected from 18 participants surviving to 7-10 years post injury using the Cognitive Subscale of the Functional Independence Measure. A subset (n = 10) of these participants also completed performance-based cognitive testing (Digit Span Test) by telephone. The IMPACT lab model was applied to determine its prognostic value in relation to very long-term outcomes as well as the additive effects of acute CSF ubiquitin C-terminal hydrolase-L1 (UCH-L1) and microtubule associated protein 2 (MAP-2) concentrations. RESULTS: The IMPACT lab model discriminated favorable versus unfavorable 7- to 10-year outcome with an area under the receiver operating characteristic curve of 0.80. Higher IMPACT lab model risk scores predicted greater extent of very long-term morbidity (ß = 0.488 p = 0.000) as well as reduced cognitive independence (ß = - 0.515, p = 0.034). Acute elevations in UCH-L1 levels were also predictive of lesser independence in cognitive activities in daily life at very long-term follow-up (ß = 0.286, p = 0.048). Addition of two CSF biomarkers significantly improved prediction of very long-term neuropsychological performance among survivors, with the overall model (including IMPACT lab score, UCH-L1, and MAP-2) explaining 89.6% of variance in cognitive performance 7-10 years post injury (p = 0.008). Higher acute UCH-L1 concentrations were predictive of poorer cognitive performance (ß = - 0.496, p = 0.029), whereas higher acute MAP-2 concentrations demonstrated a strong cognitive protective effect (ß = 0.679, p = 0.010). CONCLUSIONS: Although preliminary, results suggest that existing prognostic models, including models with incorporation of CSF markers, may be applied to predict outcome of severe TBI years after injury. Continued research is needed examining early predictors of longer-term outcomes following TBI to identify potential targets for clinical trials that could impact long-ranging functional and cognitive outcomes.

Kollidon VA64 Treatment in Traumatic Brain Injury: Operation Brain Trauma Therapy.

Loss of plasmalemmal integrity may mediate cell death after traumatic brain injury (TBI). Prior studies in controlled cortical impact (CCI) indicated that the membrane resealing agent Kollidon VA64 improved histopathological and functional outcomes. Kollidon VA64 was therefore selected as the seventh therapy tested by the Operation Brain Trauma Therapy consortium, across three pre-clinical TBI rat models: parasagittal fluid percussion injury (FPI), CCI, and penetrating ballistic-like brain injury (PBBI). In each model, rats were randomized to one of four exposures (7-15/group): (1) sham; (2) TBI+vehicle; (3) TBI+Kollidon VA64 low-dose (0.4 g/kg); and (4) TBI+Kollidon VA64 high-dose (0.8 g/kg). A single intravenous VA64 bolus was given 15 min post-injury. Behavioral, histopathological, and serum biomarker outcomes were assessed over 21 days generating a 22-point scoring matrix per model. In FPI, low-dose VA64 produced zero points across behavior and histopathology. High-dose VA64 worsened motor performance compared with TBI-vehicle, producing -2.5 points. In CCI, low-dose VA64 produced intermediate benefit on beam balance and the Morris water maze (MWM), generating +3.5 points, whereas high-dose VA64 showed no effects on behavior or histopathology. In PBBI, neither dose altered behavior or histopathology. Regarding biomarkers, significant increases in glial fibrillary acidic protein (GFAP) levels were seen in TBI versus sham at 4 h and 24 h across models. Benefit of low-dose VA64 on GFAP was seen at 24 h only in FPI. Ubiquitin C-terminal hydrolase-L1 (UCH-L1) was increased in TBI compared with vehicle across models at 4 h but not at 24 h, without treatment effects. Overall, low dose VA64 generated +4.5 points (+3.5 in CCI) whereas high dose generated -2.0 points. The modest/inconsistent benefit observed reduced enthusiasm to pursue further testing.

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

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

Glibenclamide Treatment in Traumatic Brain Injury: Operation Brain Trauma Therapy.

Glibenclamide (GLY) is the sixth drug tested by the Operation Brain Trauma Therapy (OBTT) consortium based on substantial pre-clinical evidence of benefit in traumatic brain injury (TBI). Adult Sprague-Dawley rats underwent fluid percussion injury (FPI; n = 45), controlled cortical impact (CCI; n = 30), or penetrating ballistic-like brain injury (PBBI; n = 36). Efficacy of GLY treatment (10-µg/kg intraperitoneal loading dose at 10 min post-injury, followed by a continuous 7-day subcutaneous infusion [0.2 µg/h]) on motor, cognitive, neuropathological, and biomarker outcomes was assessed across models. GLY improved motor outcome versus vehicle in FPI (cylinder task, p < 0.05) and CCI (beam balance, p < 0.05; beam walk, p < 0.05). In FPI, GLY did not benefit any other outcome, whereas in CCI, it reduced 21-day lesion volume versus vehicle (p < 0.05). On Morris water maze testing in CCI, GLY worsened performance on hidden platform latency testing versus sham (p < 0.05), but not versus TBI vehicle. In PBBI, GLY did not improve any outcome. Blood levels of glial fibrillary acidic protein and ubiquitin carboxyl terminal hydrolase-1 at 24 h did not show significant treatment-induced changes. In summary, GLY showed the greatest benefit in CCI, with positive effects on motor and neuropathological outcomes. GLY is the second-highest-scoring agent overall tested by OBTT and the only drug to reduce lesion volume after CCI. Our findings suggest that leveraging the use of a TBI model-based phenotype to guide treatment (i.e., GLY in contusion) might represent a strategic choice to accelerate drug development in clinical trials and, ultimately, achieve precision medicine in TBI.

Circulating GFAP and Iba-1 levels are associated with pathophysiological sequelae in the thalamus in a pig model of mild TBI.

Serum biomarkers are promising tools for evaluating patients following traumatic brain injury (TBI). However, their relationship with diffuse histopathology remains unclear. Additionally, translatability is a focus of neurotrauma research, however, studies using translational animal models are limited. Here, we evaluated associations between circulating biomarkers and acute thalamic histopathology in a translational micro pig model of mTBI. Serum samples were collected pre-injury, and 1 min-6 h following mTBI. Markers of neuronal injury (Ubiquitin Carboxy-terminal Hydrolase L1 [UCH-L1]), microglial/macrophage activation (Ionized calcium binding adaptor molecule-1 [Iba-1]) and interleukin-6 [IL-6]) and astrogliosis/astrocyte damage (glial fibrillary acidic protein [GFAP]) were measured. Axonal injury and histological features of neurons and glia were also investigated using immunofluorescent labeling and correlated to serum levels of the associated biomarkers. Consistent with prior experimental and human studies, GFAP, was highest at 6 h post-injury, while no substantial changes were observed in UCH-L1, Iba-1 or IL-6 over 6 h. This study also found promising associations between thalamic glial histological signatures and ensuing release of Iba-1 and GFAP into the circulation. Our findings suggest that in diffuse injury, monitoring serum Iba-1 and GFAP levels can provide clinically relevant insight into the underlying acute pathophysiology and biomarker release kinetics following mTBI, providing previously underappreciated diagnostic capability.

A Prospective Study of Acute Blood-Based Biomarkers for Sport-Related Concussion.

OBJECTIVE: Prospectively characterize changes in serum proteins following sport-related concussion and determine whether candidate biomarkers discriminate concussed athletes from controls and are associated with duration of symptoms following concussion. METHODS: High school and collegiate athletes were enrolled between 2015 and 2018. Blood was collected at preinjury baseline and within 6 hours (early acute) and at 24 to 48 hours (late acute) following concussion in football players (n = 106), matched uninjured football players (n = 84), and non-contact-sport athletes (n = 50). Glial fibrillary acidic protein, ubiquitin c-terminal hydrolase-L1, S100 calcium binding protein B, alpha-II-spectrin breakdown product 150, interleukin 6, interleukin 1 receptor antagonist, and c-reactive protein were measured in serum. Linear models assessed changes in protein concentrations over time. Receiver operating curves quantified the discrimination of concussed athletes from controls. A Cox proportional hazard model determined whether proteins were associated with symptom recovery. RESULTS: All proteins except glial fibrillary acidic protein and c-reactive protein were significantly elevated at the early acute phase postinjury relative to baseline and both control groups and discriminated concussed athletes from controls with areas under the curve of 0.68 to 0.84. The candidate biomarkers also significantly improved the discrimination of concussed athletes from noncontact controls compared to symptom severity alone. Glial fibrillary acidic protein was elevated postinjury relative to baseline in concussed athletes with a loss of consciousness or amnesia. Finally, early acute levels of interleukin 1 receptor antagonist were associated with the number of days to symptom recovery. INTERPRETATION: Brain injury and inflammatory proteins show promise as objective diagnostic biomarkers for sport-related concussion, and inflammatory markers may provide prognostic value. ANN NEUROL 2020;87:907-920.

Acute Effects of Sport-Related Concussion on Serum Glial Fibrillary Acidic Protein, Ubiquitin C-Terminal Hydrolase L1, Total Tau, and Neurofilament Light Measured by a Multiplex Assay.

We prospectively evaluated serum concentrations of glial fibrillary acidic protein (GFAP), ubiquitin c-terminal hydrolase L1 (UCH-L1), total tau (T-Tau), and neurofilament light (NF-L) from collegiate athletes at baseline and acutely after sport-related concussion (SRC) using the Quanterix Neurology 4Plex "B" (N4PB) multiplex assay. Uninjured controls were matched on age, sex, race, sport, and concussion history. Clinical outcomes included acute symptom severity, balance, rapid automated naming, computerized cognitive testing, and recovery duration. Baseline (n = 110; median [interquartile range] age = 19 [18-20] years, 54% male, 61% white/Caucasian) and post-SRC (n = 36; median [interquartile range] age = 19 [18-20] years, 50% male, 61% white/Caucasian) blood samples were analyzed. We observed post-SRC elevations from baseline for GFAP (p = 0.001, d = 1.7), T-Tau (p = 0.004, d = 1.3), and NF-L (p = 0.010, d = 1.1). GFAP (area under the curve [AUC] = 0.958, 95% confidence interval [CI] 0.927-0.989, p < 0.001) and NF-L (AUC = 0.904, 95% CI 0.851-0.957, p < 0.001) accurately discriminated SRC from control cases. There were no associations between biomarker concentrations and clinical measurements post-SRC or recovery duration. These findings suggest that, using the multiplex assay, GFAP, T-Tau, and NF-L elevate from baseline acutely after SRC, and both GFAP and NF-L excellently distinguished concussed from control cases. Serum biomarker changes do not necessarily correspond with clinical measurements or recovery duration.

Intracranial Pressure Monitoring in Experimental Traumatic Brain Injury: Implications for Clinical Management.

Traumatic brain injury (TBI) is often associated with long-term disability and chronic neurological sequelae. One common contributor to unfavorable outcomes is secondary brain injury, which is potentially treatable and preventable through appropriate management of patients in the neurosurgical intensive care unit. Intracranial pressure (ICP) is currently the predominant neurological-specific physiological parameter used to direct the care of severe TBI (sTBI) patients. However, recent clinical evidence has called into question the association of ICP monitoring with improved clinical outcome. The detailed cellular and molecular derangements associated with intracranial hypertension (IC-HTN) and their relationship to injury phenotype and neurological outcomes are not completely understood. Various animal models of TBI have been developed, but the clinical applicability of ICP monitoring in the pre-clinical setting has not been well-characterized. Linking basic mechanistic studies in translational TBI models with investigation of ICP monitoring that more faithfully replicates the clinical setting will provide clinical investigators with a more informed understanding of the pathophysiology of IC-HTN, thus facilitating development of improved therapies for sTBI patients.

Exploratory study of sport-related concussion effects on peripheral micro-RNA expression.

OBJECTIVE: Explore changes in micro-RNA (miRNA) expression in blood after sport-related concussion (SRC) in collegiate athletes. METHODS: Twenty-seven collegiate athletes (~41% male, ~75% white, age 18.8 ± 0.8 years) provided both baseline and post-SRC blood samples. Serum was analyzed for expression of miR-153-3p (n = 27), miR-223-3p (n = 23), miR-26a-5p (n = 26), miR-423-3p (n = 23), and miR-let-7a-5p (n = 23) at both time points via quantitative polymerase chain reaction (qPCR). Nonparametric analyses were used to compare miRNA expression changes between baseline and SRC and to evaluate associations with clinical outcomes (symptom severity, cognition, balance, and oculomotor function, and clinical recovery time). RESULTS: Participants manifested a significant increase in miRNA expression following SRC for miR153-3p (Z = -2.180, p = .029, 59% of the participants increased post-SRC), miR223-3p (Z = -1.998, p = .046, 70% increased), and miR-let-7a-5p (Z = -2.190, p = .029, 65% increased). There were no statistically significant associations between changes in miRNA expression and clinical test scores, acute symptom severity, or clinical recovery time. CONCLUSION: MiR-153-3p, miR-223-3p, and miR-let-7a-5p were significantly upregulated acutely following SRC in male and female collegiate athletes compared to baseline levels, though several athletes demonstrated no change or a decrease in expression. The biological mechanisms and functional implications of the increased expression of these circulating miRNA are unclear and require more research, as does their relevance to clinical outcomes.

Serum-Based Phospho-Neurofilament-Heavy Protein as Theranostic Biomarker in Three Models of Traumatic Brain Injury: An Operation Brain Trauma Therapy Study.

Glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase (UCH-L1), markers of glial and neuronal cell body injury, respectively, have been previously selected by the Operation Brain Trauma Therapy (OBTT) pre-clinical therapy and biomarker screening consortium as drug development tools. However, traumatic axonal injury (TAI) also represents a major consequence and determinant of adverse outcomes after traumatic brain injury (TBI). Thus, biomarkers capable of assessing TAI are much needed. Neurofilaments (NFs) are found exclusively in axons. Here, we evaluated phospho-neurofilament-H (pNF-H) protein as a possible new TAI marker in serum and cerebrospinal fluid (CSF) across three rat TBI models in studies carried out by the OBTT consortium, namely, controlled cortical impact (CCI), parasagittal fluid percussion (FPI), and penetrating ballistics-like brain injury (PBBI). We indeed found that CSF and serum pNF-H levels are robustly elevated by 24 h post-injury in all three models. Further, in previous studies by OBTT, levetiracetam showed the most promising benefits, whereas nicotinamide showed limited benefit only at high dose (500 mg/kg). Thus, serum samples from the same repository collected by OBTT were evaluated. Treatment with 54 mg/kg intravenously of levetiracetam in the CCI model and 170 mg/kg in the PBBI model significantly attenuated pNF-H levels at 24 h post-injury as compared to respective vehicle groups. In contrast, nicotinamide (50 or 500 mg/kg) showed no reduction of pNF-H levels in CCI or PBBI models. Our current study suggests that pNF-H is a useful theranostic blood-based biomarker for TAI across different rodent TBI models. In addition, our data support levetiracetam as the most promising TBI drug candidate screened by OBTT to date.

Concussion BASICS III: Serum biomarker changes following sport-related concussion.

OBJECTIVE: To evaluate changes in serum biomarker concentrations (ß-amyloid peptide 42 [Aß42], total tau, ubiquitin carboxy-terminal hydrolyzing enzyme L1, S100 calcium binding protein B [S100B], glial fibrillary acidic protein [GFAP], microtubule associated protein 2 [MAP2], and 2',3'-cyclic-nucleotide 3'-phosphodiesterase [CNPase]) after sport-related concussion (SRC) in a sample of collegiate athletes. Associations with clinical outcomes were also investigated. METHODS: Participants in this case-control study included 36 athletes (50% male, 61% white, aged 19.7 ± 1.0 years) with SRC. Twenty-nine also had baseline blood drawn, allowing for within-patient analyses of concentration changes. Between-group analyses incorporated 86 demographically matched controls (51% male, 63% white, aged 19.6 ± 1.1 years). Biomarker sensitivity/specificity for SRC vs controls and relative to standardized normative cutoffs was evaluated (receiver operating characteristics). We also analyzed associations between post-SRC clinical outcomes and both biomarker change from baseline and post-SRC concentrations. RESULTS: The majority of blood samples had concentrations of GFAP, MAP2, and CNPase below limits of quantification. Within-patient analyses indicated elevated S100B after SRC (p = 0.003, 67% of patients elevated), especially for blood samples collected <4 hours post-SRC (88% of patients). Significant between-group differences were limited to blood draws <4 hours post-SRC: Aß42 (81% of SRC > control median, area under the curve [AUC] = 0.75 [95% confidence interval 0.59-0.91]), total tau (75% SRC > control, AUC = 0.74 [0.56-0.79]), and S100B (88% SRC > control; AUC [specific to white race] = 0.82 [0.72-0.93]). Using standardized normative cutoffs (z > 1.0), specificity ranged from 79.1% to 89.3% while sensitivity was <70%. Biomarkers were not associated with clinical outcomes. CONCLUSION: For SRC, diagnostic accuracy of serum biomarkers appears best if blood is collected within a few hours. Accurate blood marker identification of SRC appears somewhat dependent on the "healthy" comparison. Additional research must evaluate whether physiologic changes in the absence of clinical changes, or vice versa, are relevant for concurrent or future neurologic health. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that certain serum biomarkers are elevated from baseline and higher than demographically matched controls after sport-related concussion.

Chronic Upregulation of Cleaved-Caspase-3 Associated with Chronic Myelin Pathology and Microvascular Reorganization in the Thalamus after Traumatic Brain Injury in Rats.

Traumatic brain injury (TBI) is associated with long-term disabilities and devastating chronic neurological complications including problems with cognition, motor function, sensory processing, as well as behavioral deficits and mental health problems such as anxiety, depression, personality change and social unsuitability. Clinical data suggest that disruption of the thalamo-cortical system including anatomical and metabolic changes in the thalamus following TBI might be responsible for some chronic neurological deficits following brain trauma. Detailed mechanisms of these pathological processes are not completely understood. The goal of this study was to evaluate changes in the thalamus following TBI focusing on cleaved-caspase-3, a specific effector of caspase pathway activation and myelin and microvascular pathologies using immuno- and histochemistry at different time points from 24 h to 3 months after controlled cortical impact (CCI) in adult Sprague-Dawley rats. Significant increases in cleaved-caspase-3 immunoreactivity in the thalamus were observed starting one month and persisting for at least three months following experimental TBI. Further, the study demonstrated an association of cleaved-caspase-3 with the demyelination of neuronal processes and tissue degeneration in the gray matter in the thalamus, as reflected in alterations of myelinated fiber integrity (luxol fast blue) and decreases in myelin basic protein (MBP) immunoreactivity. The immunofluorescent counterstaining of cleaved-caspase-3 with endothelial barrier antigen (EBA), a marker of blood-brain barrier, revealed limited direct and indirect associations of cleaved caspase-3 with blood-brain barrier damage. These results demonstrate for the first time a significant chronic upregulation of cleaved-caspase-3 in selected thalamic regions associated with cortical regions directly affected by CCI injury. Further, our study is also the first to report that significant upregulation of cleaved-caspase-3 in selected ipsilateral thalamic regions is associated with microvascular reorganization reflected in the significant increases in the number of microvessels with blood-brain barrier alterations detected by EBA staining. These findings provide new insights into potential mechanisms of TBI cell death involving chronic activation of caspase-3 associated with disrupted cortico-thalamic and thalamo-cortical connectivity. Moreover, this study offers the initial evidence that this upregulation of activated caspase-3, delayed degeneration of myelinated nerve fibers and microvascular reorganization with impaired blood-brain barrier integrity in the thalamus might represent reciprocal pathological processes affecting neuronal networks and brain function at the chronic stages of TBI.

Multi-Center Pre-clinical Consortia to Enhance Translation of Therapies and Biomarkers for Traumatic Brain Injury: Operation Brain Trauma Therapy and Beyond.

Current approaches have failed to yield success in the translation of neuroprotective therapies from the pre-clinical to the clinical arena for traumatic brain injury (TBI). Numerous explanations have been put forth in both the pre-clinical and clinical arenas. Operation Brain Trauma Therapy (OBTT), a pre-clinical therapy and biomarker screening consortium has, to date, evaluated 10 therapies and assessed three serum biomarkers in nearly 1,500 animals across three rat models and a micro pig model of TBI. OBTT provides a unique platform to exploit heterogeneity of TBI and execute the research needed to identify effective injury specific therapies toward precision medicine. It also represents one of the first multi-center pre-clinical consortia for TBI, and through its work has yielded insight into the challenges and opportunities of this approach. In this review, important concepts related to consortium infrastructure, modeling, therapy selection, dosing and target engagement, outcomes, analytical approaches, reproducibility, and standardization will be discussed, with a focus on strategies to embellish and improve the chances for future success. We also address issues spanning the continuum of care. Linking the findings of optimized pre-clinical consortia to novel clinical trial designs has great potential to help address the barriers in translation and produce successes in both therapy and biomarker development across the field of TBI and beyond.

Correlating Oxygen Delivery During Cardiopulmonary Bypass With the Neurologic Injury Biomarker Ubiquitin C-Terminal Hydrolase L1 (UCH-L1).

OBJECTIVE: The authors sought to assess the relationship between low oxygen delivery (DO2) during cardiopulmonary bypass (CPB) and a neuron-specific biomarker of neurologic injury, ubiquitin C-terminal hydrolase L1 (UCH-L1). DESIGN: Retrospective analysis of patient charts and prospectively collected blood samples. SETTING: University-affiliated tertiary care hospital. PARTICIPANTS: Adult patients undergoing cardiac surgery on CPB. INTERVENTIONS: Serum UCH-L1 levels were drawn at baseline and 6 and 24 hours after CPB cessation. DO2 was computed from perfusion records, with area-under-the-curve (AUC) computations performed to account for distance of DO2 excursions below predefined DO2 thresholds and the amount of time spent below them. Strokes were defined radiographically using computed tomography and magnetic resonance imaging. MEASUREMENTS AND MAIN RESULTS: Forty-three adults were included (median age 65 y, interquartile range 59-72). Three patients experienced strokes (imaged at 2, 7, and 8 d postoperatively). Most patients underwent isolated coronary artery bypass grafting (41%, 18 patients) or isolated aortic valve replacement (30%, 13). Median UCH-L1 levels differed from baseline to 6 and 24 hours after CPB (40, 232, and 166 pg/mL, respectively; p < 0.001). On multivariable linear regression analysis controlling for baseline and surgical variables, only DO2 AUC <225 was significantly associated with 6-hour UCH-L1 levels (p = 0.001), whereas only DO2 AUC <300 was significantly associated with 24- hour levels (p < 0.001). The 3 patients who experienced radiographic strokes had nonsignificantly elevated 24-hour UCH-L1 levels compared with control patients (585 v 151 pg/mL, p = 0.11). CONCLUSIONS: This is the first study to demonstrate an independent association between DO2 during CPB and elevations of a brain injury biomarker; additional study is needed to clarify the clinical significance of these results.

Pre-Clinical Testing of Therapies for Traumatic Brain Injury.

Despite the large number of promising neuroprotective agents identified in experimental traumatic brain injury (TBI) studies, none has yet shown meaningful improvements in long-term outcome in clinical trials. To develop recommendations and guidelines for pre-clinical testing of pharmacological or biological therapies for TBI, the Moody Project for Translational Traumatic Brain Injury Research hosted a symposium attended by investigators with extensive experience in pre-clinical TBI testing. The symposium participants discussed issues related to pre-clinical TBI testing including experimental models, therapy and outcome selection, study design, data analysis, and dissemination. Consensus recommendations included the creation of a manual of standard operating procedures with sufficiently detailed descriptions of modeling and outcome measurement procedures to permit replication. The importance of the selection of clinically relevant outcome variables, especially related to behavior testing, was noted. Considering the heterogeneous nature of human TBI, evidence of therapeutic efficacy in multiple, diverse (e.g., diffuse vs. focused) rodent models and a species with a gyrencephalic brain prior to clinical testing was encouraged. Basing drug doses, times, and routes of administration on pharmacokinetic and pharmacodynamic data in the test species was recommended. Symposium participants agreed that the publication of negative results would reduce costly and unnecessary duplication of unsuccessful experiments. Although some of the recommendations are more relevant to multi-center, multi-investigator collaborations, most are applicable to pre-clinical therapy testing in general. The goal of these consensus guidelines is to increase the likelihood that therapies that improve outcomes in pre-clinical studies will also improve outcomes in TBI patients.

Operation Brain Trauma Therapy: 2016 Update.

Operation brain trauma therapy (OBTT) is a multi-center, pre-clinical drug and biomarker screening consortium for traumatic brain injury (TBI). Therapies are screened across three rat models (parasagittal fluid percussion injury, controlled cortical impact [CCI], and penetrating ballistic-like brain injury). Operation brain trauma therapy seeks to define therapies that show efficacy across models that should have the best chance in randomized clinical trials (RCTs) and/or to define model-dependent therapeutic effects, including TBI protein biomarker responses, to guide precision medicine-based clinical trials in targeted pathologies. The results of the first five therapies tested by OBTT (nicotinamide, erythropoietin, cyclosporine [CsA], simvastatin, and levetiracetam) were published in the Journal of Neurotrauma. Operation brain trauma therapy now describes preliminary results on four additional therapies (glibenclamide, kollidon-VA64, AER-271, and amantadine). To date, levetiracetam was beneficial on cognitive outcome, histology, and/or biomarkers in two models. The second most successful drug, glibenclamide, improved motor function and histology in CCI. Other therapies showed model-dependent effects (amantadine and CsA). Critically, glial fibrillary acidic protein levels predicted treatment effects. Operation brain trauma therapy suggests that levetiracetam merits additional pre-clinical and clinical evaluation and that glibenclamide and amantadine merit testing in specific TBI phenotypes. Operation brain trauma therapy has established that rigorous, multi-center consortia could revolutionize TBI therapy and biomarker development.