GFAP versus S100B in serum after traumatic brain injury: relationship to brain damage and outcome

Microglial priming and enhanced reactivity to secondary insult in aging, and traumatic CNS injury, and neurodegenerative disease

Glia of the central nervous system (CNS) help to maintain homeostasis in the brain and support efficient neuronal function. Microglia are innate immune cells of the brain that mediate responses to pathogens and injury. They have key roles in phagocytic clearing, surveying the local microenvironment and propagating inflammatory signals. An interruption in homeostasis induces a cascade of conserved adaptive responses in glia. This response involves biochemical, physiological and morphological changes and is associated with the production of cytokines and secondary mediators that influence synaptic plasticity, cognition and behavior. This reorganization of host priorities represents a beneficial response that is normally adaptive but may become maladaptive when the profile of microglia is compromised. For instance, microglia can develop a primed or pro-inflammatory mRNA, protein and morphological profile with aging, traumatic brain injury and neurodegenerative disease. As a result, primed microglia exhibit an exaggerated inflammatory response to secondary and sub-threshold challenges. Consequences of exaggerated inflammatory responses by microglia include the development of cognitive deficits, impaired synaptic plasticity and accelerated neurodegeneration. Moreover, impairments in regulatory systems in these circumstances may make microglia more resistant to negative feedback and important functions of glia can become compromised and dysfunctional. Overall, the purpose of this review is to discuss key concepts of microglial priming and immune-reactivity in the context of aging, traumatic CNS injury and neurodegenerative disease. This article is part of a Special Issue entitled 'Neuroimmunology and Synaptic Function'.

Comparison of the performances of copeptin and multiple biomarkers in long-term prognosis of severe traumatic brain injury

Enhanced blood levels of copeptin correlate with poor clinical outcomes after acute critical illness. This study aimed to compare the prognostic performances of plasma concentrations of copeptin and other biomarkers like myelin basic protein, glial fibrillary astrocyte protein, S100B, neuron-specific enolase, phosphorylated axonal neurofilament subunit H, Tau and ubiquitin carboxyl-terminal hydrolase L1 in severe traumatic brain injury. We recruited 102 healthy controls and 102 acute patients with severe traumatic brain injury. Plasma concentrations of these biomarkers were determined using enzyme-linked immunosorbent assay. Their prognostic predictive performances of 6-month mortality and unfavorable outcome (Glasgow Outcome Scale score of 1-3) were compared. Plasma concentrations of these biomarkers were statistically significantly higher in all patients than in healthy controls, in non-survivors than in survivors and in patients with unfavorable outcome than with favorable outcome. Areas under receiver operating characteristic curves of plasma concentrations of these biomarkers were similar to those of Glasgow Coma Scale score for prognostic prediction. Except plasma copeptin concentration, other biomarkers concentrations in plasma did not statistically significantly improve prognostic predictive value of Glasgow Coma Scale score. Copeptin levels may be a useful tool to predict long-term clinical outcomes after severe traumatic brain injury and have a potential to assist clinicians.

Serum biomarkers to evaluate the integrity of the neurovascular unit

Biomarkers have the potential to enable the clinicians to screen infants for brain injury, monitor progression of disease, identify injured brain regions, assess efficacy of neuroprotective therapies, and offer hope to identify the timing of the injury, thus shedding light on the potential pathophysiology and the most effective therapy. Currently, clinicians do not routinely use biomarkers to care for neonates with Neonatal Encephalopathy (NE) and brain injury due to prenatal hypoxia-asphyxia. This review will cover potential biomarkers of the neurovascular unit in the setting of NE that (i) can help assess the degree or severity of encephalopathy at birth; (ii) can help monitor progression of disease process and efficacy of neuroprotective therapy; (iii) can help assess neurodevelopmental outcome. These biomarkers will be summarized in two categories: 1) Specific biomarkers targeting the neurovascular unit such as glial fibrillary acidic protein (GFAP), ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1), S100B, and neuron specific enolase (NSE) and 2) general inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1b (IL-1b), and pNF-H, among others.

Effect of valproic acid and injury on lesion size and endothelial glycocalyx shedding in a rodent model of isolated traumatic brain injury

BACKGROUND

In isolated traumatic brain injury (TBI), little is known about the endothelial response and the effects of endothelial glycocalyx shedding. We have previously shown that treatment with valproic acid (VPA) improves outcomes following TBI and hemorrhagic shock.In this model, we hypothesized that severe isolated TBI would cause shedding of the endothelial glycocalyx, as measured by serum syndecan-1 (sSDC-1) levels. We further hypothesized that VPA treatment would reduce this response and reduce lesion size volume.

METHODS

Forty Sprague-Dawley rats were allocated to TBI + VPA (n = 8), TBI + saline vehicle control infusion (n = 8), sham + saline vehicle control infusion (n = 6), or sham + VPA (n = 8). TBI animals were subjected to severe controlled cortical impact and killed 6 hours after injury. VPA 300 mg/kg was given as an intravenous bolus 30 minutes after injury. Serum samples were analyzed for sSDC-1, and lesion size was determined on Nissl-stained cryosections.

RESULTS

sSDC-1 was significantly elevated in injured compared with uninjured animals at 3 hours (p = 0.0009) and 6 hours (p = 0.0007) after injury. This effect was significantly more pronounced in the animals treated with VPA (p = 0.019) 3 hours after injury, in which sSDC-1 levels were also significantly inversely correlated with lesion size (ρ = -0.55, p = 0.038).Lesion size was significantly smaller in TBI + VPA (40.45 mm ± 13.83 mm) as compared with vehicle control (59.57 mm ± 16.83 mm) (p = 0.023).

CONCLUSION

Severe isolated TBI caused shedding of the endothelial glycocalyx. Treatment with VPA was associated with increased glycocalyx shedding and reduced lesion size volume in injured animal.

Detection of neurofilament-H in serum as a diagnostic tool to predict injury severity in patients who have suffered mild traumatic brain injury

OBJECT

In previous studies of traumatic brain injury (TBI), neural biomarkers of injury correlate with injury severity and predict neurological outcome. The object of this paper was to characterize neurofilament-H (NFL-H) as a predictor of injury severity in patients who have suffered mild TBI (mTBI). Thus, the authors hypothesized that phosphorylated NFL-H (pNFL-H) levels are higher in mTBI patients than in healthy controls and identify which subjects experienced a more severe injury such as skull fractures, intracranial hemorrhaging, and/or contusions as detected by CT scans.

METHODS

In this prospective clinical study, blood (8 ml) was collected from subjects (n = 34) suffering from mTBI (as defined by the American Congress of Rehabilitation and Glasgow Coma Scale scores between 13 and 15) at Parkland Hospital, Dallas, Texas, on Days 1 and 3 after injury). Additional clinical findings from the CT scans were also used to categorize the TBI patients into those with and those without clinical findings on the scans (CT+ and CTgroups, respectively). The serum levels of pNFL-H were measured using the enzyme-linked immunosorbent assay.

RESULTS

Compared with healthy controls, the mTBI patients exhibited a significant increase in the serum levels of pNFL-H on Days 1 (p = 0.00001) and 3 (p = 0.0001) after TBI. An inverse correlation was observed between pNFL-H serum levels and Glasgow Coma Scale scores, which was significant. Additionally, using receiver operating characteristic curve analysis to compare the mTBI cases with controls to determine sensitivity and specificity, an area under the curve of 100% was achieved for both (p = 0.0001 for both). pNFL-H serum levels were only significantly higher on Day 1 in mTBI patients in the CT+ group (p < 0.008) compared with the CT- group. The area under the curve (82.5%) for the CT+ group versus the CT- group was significant (p = 0.021) with a sensitivity of 87.5% and a specificity of 70%, using a cutoff of 1071 pg/ml of pNFL-H in serum.

CONCLUSIONS

This study describes the serum profile of pNFL-H in patients suffering from mTBI with and without CT findings on Days 1 and 3 after injury. These results suggest that detection of pNFL-H may be useful in determining which individuals require CT imaging to assess the severity of their injury.

Biomarkers and acute brain injuries: interest and limits

For patients presenting with acute brain injury (such as traumatic brain injury, subarachnoid haemorrhage and stroke), the diagnosis and identification of intracerebral lesions and evaluation of the severity, prognosis and treatment efficacy can be challenging. The complexity and heterogeneity of lesions after brain injury are most probably responsible for this difficulty. Patients with apparently comparable brain lesions on imaging may have different neurological outcomes or responses to therapy. In recent years, plasmatic and cerebrospinal fluid biomarkers have emerged as possible tools to distinguish between the different pathophysiological processes. This review aims to summarise the plasmatic and cerebrospinal fluid biomarkers evaluated in subarachnoid haemorrhage, traumatic brain injury and stroke, and to clarify their related interests and limits for diagnosis and prognosis. For subarachnoid haemorrhage, particular interest has been focused on the biomarkers used to predict vasospasm and cerebral ischaemia. The efficacy of biomarkers in predicting the severity and outcome of traumatic brain injury has been stressed. The very early diagnostic performance of biomarkers and their ability to discriminate ischaemic from haemorrhagic stroke were studied.

S100B and NSE as useful postmortem biochemical markers of traumatic brain injury in autopsy cases

Postmortem analysis of relevant biomarkers might aid in characterizing causes of death and survival times in legal medicine. However, there are still no sufficiently established results of practical postmortem biochemical investigations in cases of traumatic brain injury (TBI). The two biomarkers--S100 protein subunit B (S100B) and neuronal specific enolase (NSE)--could be of special interest. Therefore, the aim of the present study was to investigate changes in their postmortem levels for further determination of brain damage in TBI. In 17 cases of TBI (average age, 58 years) and in 23 controls with different causes of death (average age, 59 years), serum and cerebrospinal fluid (CSF) samples were analyzed with a chemiluminescence immunoassay for marker expression. An increase in serum S100B, as well as a subsequent decrease after survival times>4 days, were detected in TBI cases (p<0.01). CSF NSE values >6,000 ng/mL and CSF S100B levels >10,000 ng/mL seem to indicate a TBI survival time of at least 15 min (p<0.01). It is of particular interest that CSF S100B levels (p<0.01) and serum S100B levels (p<0.05) as well as CSF NSE values (p<0.01) were significantly higher in TBI cases in comparison to the controls, especially when compared with fatal non-head injuries. In conclusion, the present findings emphasize that S100B and NSE are useful markers in postmortem biochemistry in cases of suspected TBI. Further, S100B may be helpful to estimate the survival time of fatal injuries in legal medicine.

GFAP-BDP as an acute diagnostic marker in traumatic brain injury: results from the prospective transforming research and clinical knowledge in traumatic brain injury study

Reliable diagnosis of traumatic brain injury (TBI) is a major public health need. Glial fibrillary acidic protein (GFAP) is expressed in the central nervous system, and breakdown products (GFAP-BDP) are released following parenchymal brain injury. Here, we evaluate the diagnostic accuracy of elevated levels of plasma GFAP-BDP in TBI. Participants were identified as part of the prospective Transforming Research And Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) Study. Acute plasma samples (<24 h post-injury) were collected from patients presenting with brain injury who had CT imaging. The ability of GFAP-BDP level to discriminate patients with demonstrable traumatic lesions on CT, and with failure to return to pre-injury baseline at 6 months, was evaluated by the area under the receiver operating characteristic curve (AUC). Of the 215 patients included for analysis, 83% had mild, 4% had moderate, and 13% had severe TBI; 54% had acute traumatic lesions on CT. The ability of GFAP-BDP level to discriminate patients with traumatic lesions on CT as evaluated by AUC was 0.88 (95% confidence interval [CI], 0.84-0.93). The optimal cutoff of 0.68 ng/mL for plasma GFAP-BDP level was associated with a 21.61 odds ratio for traumatic findings on head CT. Discriminatory ability of unfavorable 6 month outcome was lower, AUC 0.65 (95% CI, 0.55-0.74), with a 2.07 odds ratio. GFAP-BDP levels reliably distinguish the presence and severity of CT scan findings in TBI patients. Although these findings confirm and extend prior studies, a larger prospective trial is still needed to validate the use of GFAP-BDP as a routine diagnostic biomarker for patient care and clinical research. The term "mild" continues to be a misnomer for this patient population, and underscores the need for evolving classification strategies for TBI targeted therapy. (ClinicalTrials.gov number NCT01565551; NIH Grant 1RC2 NS069409).

S100B levels are affected by older age but not by alcohol intoxication following mild traumatic brain injury

Introduction

Biomarkers of brain damage and head injury are potentially useful tools in the management of afflicted patients. Particularly S100B has received much attention and has been adapted into clinical guidelines. Alcohol intoxication and higher age (65 years and over) have been used as risk factors for serious complications following head injury. The effect of these factors on S100B levels has not been fully established in a relevant patient cohort.

Methods

We prospectively included 621 adult patients with mild traumatic brain injury (TBI) and S100B sampling. Mild TBI was defined as Glasgow Come Scale 14–15 with loss of consciousness and/or amnesia, but without high-risk factors for intracranial complications. These patients would normally require CT scanning according to local and most international guidelines. S100B was sampled within 3 hours following trauma.

Results

280 patients (45%) were intoxicated by alcohol. Alcohol intoxication had no effect on S100B levels (p = 0.65) and the performance of S100B remained unchanged in these patients. 115 patients (22%) were 65 years or older with elevated S100B levels being more common in this group compared to patients under 65 (p = 0.029). Although the sensitivity of S100B was unchanged in older patients, the specificity was poorer.

Conclusion

S100B can be used reliably in mild TBI patients with alcohol intoxication. The clinically utility of S100B in older patients may be limited by very poor specificity leading to only a small decrease in CT scanning.

Physiological monitoring of the severe traumatic brain injury patient in the intensive care unit

Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. Despite encouraging animal research, pharmacological agents and neuroprotectants have disappointed in the clinical environment. Current TBI management therefore is directed towards identification, prevention, and treatment of secondary cerebral insults that are known to exacerbate outcome after injury. This strategy is based on a variety of monitoring techniques that include the neurological examination, imaging, laboratory analysis, and physiological monitoring of the brain and other organ systems used to guide therapeutic interventions. Recent clinical series suggest that TBI management informed by multimodality monitoring is associated with improved patient outcome, in part because care is provided in a patient-specific manner. In this review we discuss physiological monitoring of the brain after TBI and the emerging field of neurocritical care bioinformatics.

Endothelial Von Willebrand factor promotes blood-brain barrier flexibility and provides protection from hypoxia and seizures in mice

OBJECTIVE

Aberrant blood-brain barrier (BBB) permeability is a hallmark pathology of many central nervous system diseases. von Willebrand factor (VWF) is stored in endothelial Weibel-Palade bodies from where it is released on activation into plasma and basement membrane. The role of VWF in endothelial homeostasis is unclear. The goal of this study was to assess the role of VWF in disease models associated with increased BBB permeability.

APPROACH AND RESULTS

We did not find any differences in BBB permeability to Evans blue dye at baseline between wild-type and VWF(-/-) animals. We next used 2 models presenting with increased BBB permeability, hypoxia/reoxygenation and pilocarpine-induced status epilepticus, to assess the response of VWF(-/-) animals. In both models, VWF(-/-) mice maintained a tighter BBB than wild-type mice. VWF(-/-) mice fared worse in both conditions, with ≈ 100% of VWF(-/-) mice dying within 120 minutes after pilocarpine administration, whereas >80% of wild-type animals survived. Investigation into the status of tight junction proteins revealed that VWF(-/-) mice expressed more claudin-5 at baseline. In vitro work confirmed that the presence of subendothelial VWF is inhibitory to claudin-5 expression.

CONCLUSIONS

VWF deficiency confers partial preservation of BBB integrity after hypoxia/reoxygenation and seizures. Surprisingly, this decrease in BBB permeability did not result in protection of animals because they demonstrated more severe pathology in both models compared with wild-type animals. These data suggest that a rigid BBB is detrimental (to the organism) during certain disease states and that VWF release may provide desired flexibility under stress.

The challenge of mild traumatic brain injury: role of biochemical markers in diagnosis of brain damage

During the past decade there has been an increasing recognition of the incidence of mild traumatic brain injury (mTBI) and a better understanding of the subtle neurological and cognitive deficits that may result from it. A substantial, albeit suboptimal, effort has been made to define diagnostic criteria for mTBI and improve diagnostic accuracy. Thus, biomarkers that can accurately and objectively detect brain injury after mTBI and, ideally, aid in clinical management are needed. In this review, we discuss the current research on serum biomarkers for mTBI including their rationale and diagnostic performances. Sensitive and specific biomarkers reflecting brain injury can provide important information regarding TBI pathophysiology and serve as candidate markers for predicting abnormal computed tomography findings and/or the development of residual deficits in patients who sustain an mTBI. We also outline the roles of biomarkers in settings of specific interest including pediatric TBI, sports concussions and military injuries, and provide perspectives on the validation of such markers for use in the clinic. Finally, emerging proteomics-based strategies for identifying novel markers will be discussed.

S100b as a prognostic biomarker in outcome prediction for patients with severe traumatic brain injury

As an astrocytic protein specific to the central nervous system, S100b is a potentially useful marker in outcome prediction after traumatic brain injury (TBI). Some studies have questioned the validity of S100b, citing the extracerebral origins of the protein as reducing the specificity of the marker. This study evaluated S100b as a prognostic biomarker in adult subjects with severe TBI (sTBI) by comparing outcomes with S100b temporal profiles generated from both cerebrospinal fluid (CSF) (n = 138 subjects) and serum (n = 80 subjects) samples across a 6-day time course. Long-bone fracture, Injury Severity Score (ISS), and isolated head injury status were variables used to assess extracerebral sources of S100b in serum. After TBI, CSF and serum S100b levels were increased over healthy controls across the first 6 days post-TBI (p ≤ 0.005 and p ≤ 0.031). Though CSF and serum levels were highly correlated during early time points post-TBI, this association diminished over time. Bivariate analysis showed that subjects who had temporal CSF profiles with higher S100b concentrations had higher acute mortality (p < 0.001) and worse Glasgow Outcome Scale (GOS; p = 0.002) and Disability Rating Scale (DRS) scores (p = 0.039) 6 months post-injury. Possibly as a result of extracerebral sources of S100b in serum, as represented by high ISS scores (p = 0.032), temporal serum profiles were associated with acute mortality (p = 0.015). High CSF S100b levels were observed in women (p = 0.022) and older subjects (p = 0.004). Multivariate logistic regression confirmed CSF S100b profiles in predicting GOS and DRS and showed mean and peak serum S100b as acute mortality predictors after sTBI.

Integration of proteomics, bioinformatics, and systems biology in traumatic brain injury biomarker discovery

Traumatic brain injury (TBI) is a major medical crisis without any FDA-approved pharmacological therapies that have been demonstrated to improve functional outcomes. It has been argued that discovery of disease-relevant biomarkers might help to guide successful clinical trials for TBI. Major advances in mass spectrometry (MS) have revolutionized the field of proteomic biomarker discovery and facilitated the identification of several candidate markers that are being further evaluated for their efficacy as TBI biomarkers. However, several hurdles have to be overcome even during the discovery phase which is only the first step in the long process of biomarker development. The high-throughput nature of MS-based proteomic experiments generates a massive amount of mass spectral data presenting great challenges in downstream interpretation. Currently, different bioinformatics platforms are available for functional analysis and data mining of MS-generated proteomic data. These tools provide a way to convert data sets to biologically interpretable results and functional outcomes. A strategy that has promise in advancing biomarker development involves the triad of proteomics, bioinformatics, and systems biology. In this review, a brief overview of how bioinformatics and systems biology tools analyze, transform, and interpret complex MS datasets into biologically relevant results is discussed. In addition, challenges and limitations of proteomics, bioinformatics, and systems biology in TBI biomarker discovery are presented. A brief survey of researches that utilized these three overlapping disciplines in TBI biomarker discovery is also presented. Finally, examples of TBI biomarkers and their applications are discussed.

Prognosis in severe brain injury

BACKGROUND

The prediction of neurologic outcome is a fundamental concern in the resuscitation of patients with severe brain injury.

OBJECTIVE

To provide an evidence-based update on neurologic prognosis following traumatic brain injury and hypoxic-ischemic encephalopathy after cardiac arrest.

DATA SOURCE

Search of the PubMed database and manual review of bibliographies from selected articles to identify original data relating to prognostic methods and outcome prediction models in patients with neurologic trauma or hypoxic-ischemic encephalopathy.

DATA SYNTHESIS AND CONCLUSION

Articles were scrutinized regarding study design, population evaluated, interventions, outcomes, and limitations. Outcome prediction in severe brain injury is reliant on features of the neurologic examination, anatomical and physiological changes identified with CT and MRI, abnormalities detected with electroencephalography and evoked potentials, and physiological and biochemical derangements at both the brain and systemic levels. Use of such information in univariable association studies generally lacks specificity in classifying neurologic outcome. Furthermore, the accuracy of established prognostic classifiers may be affected by the introduction of outcome-modifying interventions, such as therapeutic hypothermia following cardiac arrest. Although greater specificity may be achieved with scoring systems derived from multivariable models, they generally fail to predict outcome with sufficient accuracy to be meaningful at the single patient level. Discriminative models which integrate knowledge of genetic determinants and biologic processes governing both injury and repair and account for the effects of resuscitative and rehabilitative care are needed.

Biomarkers for the clinical differential diagnosis in traumatic brain injury--a systematic review

Rapid triage and decision-making in the treatment of traumatic brain injury (TBI) present challenging dilemma in "resource poor" environments such as the battlefield and developing areas of the world. There is an urgent need for additional tools to guide treatment of TBI. The aim of this review is to establish the possible use of diagnostic TBI biomarkers in (1) identifying diffuse and focal brain injury and (2) assess their potential for determining outcome, intracranial pressure (ICP), and responses to therapy. At present, there is insufficient literature to support a role for diagnostic biomarkers in distinguishing focal and diffuse injury or for accurate determination of raised ICP. Presently, neurofilament (NF), S100β, glial fibrillary acidic protein (GFAP), and ubiquitin carboxyl terminal hydrolase-L1 (UCH-L1) seemed to have the best potential as diagnostic biomarkers for distinguishing focal and diffuse injury, whereas C-tau, neuron-specific enolase (NSE), S100β, GFAP, and spectrin breakdown products (SBDPs) appear to be candidates for ICP reflective biomarkers. With the combinations of different pathophysiology related to each biomarker, a multibiomarker analysis seems to be effective and would likely increase diagnostic accuracy. There is limited research focusing on the differential diagnostic properties of biomarkers in TBI. This fact warrants the need for greater efforts to innovate sensitive and reliable biomarkers. We advocate awareness and inclusion of the differentiation of injury type and ICP elevation in further studies with brain injury biomarkers.

Application of blood-based biomarkers in human mild traumatic brain injury

Traumatic Brain Injury (TBI) is a global health concern. The majority of TBI's are mild, yet our ability to diagnose and treat mild traumatic brain injury (mTBI) is lacking. This deficiency results from a variety of issues including the difficulty in interpreting ambiguous clinically presented symptoms, and ineffective imaging techniques. Thus, researchers have begun to explore cellular and molecular based approaches to improve both diagnosis and prognosis. This has been met with a variety of challenges, including difficulty in relating biological markers to current clinical symptoms, and overcoming our lack of fundamental understanding of the pathophysiology of mTBI. However, recent adoption of high throughput technologies and a change in focus from the identification of single to multiple markers has given just optimism to mTBI research. The purpose of this review is to highlight a number of current experimental peripheral blood biomarkers of mTBI, as well as comment on the issues surrounding their clinical application and utility.

Acute diagnostic biomarkers for spinal cord injury: review of the literature and preliminary research report

OBJECTIVE

Many efforts have been made to create new diagnostic technologies for use in the diagnosis of central nervous system injury. However, there is still no consensus for the use of biomarkers in clinical acute spinal cord injury (SCI). The aims of this review are (1) to evaluate the current status of neurochemical biomarkers and (2) to discuss their potential acute diagnostic role in SCI by reviewing the literature.

METHODS

PubMed (http://www.ncbi.nlm.nih.gov/pubmed) was searched up to 2012 to identify publications concerning diagnostic biomarkers in SCI. To support more knowledge, we also checked secondary references in the primarily retrieved literature.

RESULTS

Neurofilaments, cleaved-Tau, microtubule-associated protein 2, myelin basic protein, neuron-specific enolase, S100β, and glial fibrillary acidic protein were identified as structural protein biomarkers in SCI by this review process. We could not find reports relating ubiquitin C-terminal hydrolase-L1 and α-II spectrin breakdown products, which are widely researched in other central nervous system injuries. Therefore, we present our preliminary data relating to these two biomarkers. Some of biomarkers showed promising results for SCI diagnosis and outcome prediction; however, there were unresolved issues relating to accuracy and their accessibility.

CONCLUSION

Currently, there still are not many reports focused on diagnostic biomarkers in SCI. This fact warranted the need for greater efforts to innovate sensitive and reliable biomarkers for SCI.

The role of markers of inflammation in traumatic brain injury

Within minutes of a traumatic impact, a robust inflammatory response is elicited in the injured brain. The complexity of this post-traumatic squeal involves a cellular component, comprising the activation of resident glial cells, microglia, and astrocytes, and the infiltration of blood leukocytes. The second component regards the secretion immune mediators, which can be divided into the following sub-groups: the archetypal pro-inflammatory cytokines (Interleukin-1, Tumor Necrosis Factor, Interleukin-6), the anti-inflammatory cytokines (IL-4, Interleukin-10, and TGF-beta), and the chemotactic cytokines or chemokines, which specifically drive the accumulation of parenchymal and peripheral immune cells in the injured brain region. Such mechanisms have been demonstrated in animal models, mostly in rodents, as well as in human brain. Whilst the humoral immune response is particularly pronounced in the acute phase following Traumatic brain injury (TBI), the activation of glial cells seems to be a rather prolonged effect lasting for several months. The complex interaction of cytokines and cell types installs a network of events, which subsequently intersect with adjacent pathological cascades including oxidative stress, excitotoxicity, or reparative events including angiogenesis, scarring, and neurogenesis. It is well accepted that neuroinflammation is responsible of beneficial and detrimental effects, contributing to secondary brain damage but also facilitating neurorepair. Although such mediators are clear markers of immune activation, to what extent cytokines can be defined as diagnostic factors reflecting brain injury or as predictors of long term outcome needs to be further substantiated. In clinical studies some groups reported a proportional cytokine production in either the cerebrospinal fluid or intraparenchymal tissue with initial brain damage, mortality, or poor outcome scores. However, the validity of cytokines as biomarkers is not broadly accepted. This review article will discuss the evidence from both clinical and laboratory studies exploring the validity of immune markers as a correlate to classification and outcome following TBI.

Clinical review: neuromonitoring - an update

Critically ill patients are frequently at risk of neurological dysfunction as a result of primary neurological conditions or secondary insults. Determining which aspects of brain function are affected and how best to manage the neurological dysfunction can often be difficult and is complicated by the limited information that can be gained from clinical examination in such patients and the effects of therapies, notably sedation, on neurological function. Methods to measure and monitor brain function have evolved considerably in recent years and now play an important role in the evaluation and management of patients with brain injury. Importantly, no single technique is ideal for all patients and different variables will need to be monitored in different patients; in many patients, a combination of monitoring techniques will be needed. Although clinical studies support the physiologic feasibility and biologic plausibility of management based on information from various monitors, data supporting this concept from randomized trials are still required.

Attenuation of MPTP/MPP(+) toxicity in vivo and in vitro by an 18-mer peptide derived from prosaposin

Parkinson's disease (PD) is a chronic progressive neurological disorder with an increasing incidence in the aging population. Neuroprotective and/or neuroregenerative strategies remain critical in the treatment of this increasingly prevalent disease. Prosaposin is a neurotrophic factor whose neurotrophic activity is attributed to a stretch of 12 amino acids located at the N-terminal region of saposin C. The present study was performed to investigate the protective effect and mechanism of action of a prosaposin-derived 18-mer peptide (PS18: LSELIINNATEELLIKGL) in Parkinson's disease models. We used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 1-methyl-4-phenylpyridinium ion (MPP(+))-induced dopaminergic neurotoxicity in C57BL/6J mice or SH-SY5Y cells and explored the protective effect and mechanisms of action of PS18 on dopaminergic neurons. Treatment with 2.0mg/kg PS18 significantly improved behavioral deficits, enhanced the survival of tyrosine hydroxylase-positive neurons, and decreased the activity of astrocytes in the substantia nigra and striatum in MPTP-induced PD model mice. In vitro, a Cell Counting Kit-8 assay and Hoechst 33258 staining revealed that co-treatment with 300ng/mL PS18 and 5mM MPP(+) protected against MPP(+)-induced nuclear morphological changes and attenuated cell death induced by MPP(+). We also found that PS18-FAM entered the cells, and the retention time of PS18-FAM in the cytoplasm of MPP(+)-treated cells was shorter than that of untreated cells. In addition, PS18 showed protection from MPP(+)/MPTP-induced apoptosis in the SH-SY5Y cells and dopaminergic neurons in the PD model mice via suppression of the c-Jun N-terminal kinase/c-Jun pathway; upregulation of Bcl-2; downregulation of BAX, attenuating mitochondrial damage; and inhibition of caspase-3. These findings suggest that PS18 may provide a valuable therapeutic strategy for the treatment of progressive neurodegenerative diseases such as PD.

The role of markers of inflammation in traumatic brain injury

Within minutes of a traumatic impact, a robust inflammatory response is elicited in the injured brain. The complexity of this post-traumatic squeal involves a cellular component, comprising the activation of resident glial cells, microglia, and astrocytes, and the infiltration of blood leukocytes. The second component regards the secretion immune mediators, which can be divided into the following sub-groups: the archetypal pro-inflammatory cytokines (Interleukin-1, Tumor Necrosis Factor, Interleukin-6), the anti-inflammatory cytokines (IL-4, Interleukin-10, and TGF-beta), and the chemotactic cytokines or chemokines, which specifically drive the accumulation of parenchymal and peripheral immune cells in the injured brain region. Such mechanisms have been demonstrated in animal models, mostly in rodents, as well as in human brain. Whilst the humoral immune response is particularly pronounced in the acute phase following Traumatic brain injury (TBI), the activation of glial cells seems to be a rather prolonged effect lasting for several months. The complex interaction of cytokines and cell types installs a network of events, which subsequently intersect with adjacent pathological cascades including oxidative stress, excitotoxicity, or reparative events including angiogenesis, scarring, and neurogenesis. It is well accepted that neuroinflammation is responsible of beneficial and detrimental effects, contributing to secondary brain damage but also facilitating neurorepair. Although such mediators are clear markers of immune activation, to what extent cytokines can be defined as diagnostic factors reflecting brain injury or as predictors of long term outcome needs to be further substantiated. In clinical studies some groups reported a proportional cytokine production in either the cerebrospinal fluid or intraparenchymal tissue with initial brain damage, mortality, or poor outcome scores. However, the validity of cytokines as biomarkers is not broadly accepted. This review article will discuss the evidence from both clinical and laboratory studies exploring the validity of immune markers as a correlate to classification and outcome following TBI.

Biomarkers of hypoxic-ischemic encephalopathy in newborns

As neonatal intensive care has evolved, the focus has shifted from improving mortality alone to an effort to improve both mortality and morbidity. The most frequent source of neonatal brain injury occurs as a result of hypoxic-ischemic injury. Hypoxic-ischemic injury occurs in about 2 of 1,000 full-term infants and severe injured infants will have lifetime disabilities and neurodevelopmental delays. Most recently, remarkable efforts toward neuroprotection have been started with the advent of therapeutic hypothermia and a key step in the evolution of neonatal neuroprotection is the discovery of biomarkers that enable the clinician-scientist to screen infants for brain injury, monitor progression of disease, identify injured brain regions, and assess efficacy of neuroprotective clinical trials. Lastly, biomarkers offer great hope identifying when an injury occurred shedding light on the potential pathophysiology and the most effective therapy. In this article, we will review biomarkers of HIE including S100B, neuron specific enolase, umbilical cord IL-6, CK-BB, GFAP, myelin basic protein, UCHL-1, and pNF-H. We hope to contribute to the awareness, validation, and clinical use of established as well as novel neonatal brain injury biomarkers.

Clinical validation of S100B use in management of mild head injury

Background

Despite validated guidelines, management of mild head injury (MHI) is still associated with excessive computed tomography (CT) scanning. Reports concerning serum levels of S100B have shown promise concerning safe reduction in CT scanning but clinical validation and actual impact on patient management is unclear. In 2007, S100B was introduced into emergency department (ED) clinical management routines in Halmstad, Sweden. MHI patients with low (<0.10 mikrogram/L) levels of S100B could be discharged without CT. Our aim was to examine the clinical impact and performance of S100B in clinical use for MHI patients.

Methods

Adult ([≥]18 years) patients with MHI (GCS 14–15, loss of consciousness and/or amnesia and no additional risk factors) and S100B sampling within 3 hours were prospectively included in this validation study. Patients were managed according to the adapted guidelines and management was documented. Outcome was determined with a questionnaire 3 months post-trauma and medical records to identify significant intracranial complications such as new neuroimaging, neurosurgery and/or death related to the trauma.

Results

512 patients were included. 24 (4.7%) showed traumatic abnormalities on CT and 1 patient died (0.2%). 138 patients (27%) had normal S100B levels and 374 patients (73%) showed elevated S100B levels. No patients with a normal S100B level showed significant intracranial complication. 44 patients (32%) were managed with CT despite the guidelines recommending discharge (all these CT scans were normal) and 28 patients (7%) were discharged despite a CT recommendation (follow-up was normal in all these patients). S100B had a sensitivity of 100% (95% CI 83-100%) and a specificity of 28% (95% CI 24-33%) for significant intracranial complications.

Conclusion

The clinical use of S100B within our existing guidelines for management of MHI is safe and effective. Adult MHI patients, without additional risk factors and with normal S100B levels within 3 hours of injury, can safely be discharged from the hospital.

Predictive biomarkers of recovery in traumatic brain injury

Recent advances in medicine, intensive care and diagnostic imaging modalities have led to a pronounced reduction in deaths and disability resulting from traumatic brain injury. However, there are not sufficient findings to evaluate and quantify the severity of the initial and secondary processes destructive and therefore there are not effective therapeutic measures to effectively predict the outcome. For this reason, in recent decades, researchers and clinicians have focused on specific markers of cellular brain injury to improve the diagnosis and the evaluation of outcome. Many proteins synthesized in the astroglia cells or in the neurons, such as neuron-specific enolase, S100 calcium binding protein B, myelin basic protein, creatine kinase brain isoenzyme, glial fibrillary acidic protein, plasma desoxyribonucleic acid, brain-derived neurotrophic factor, and ubiquitin carboxy-terminal hydrolase-L1, have been proposed as potential markers for cell damage in central nervous system. Usually, the levels of these proteins increase following brain injury and are found in increasing concentrations in the cerebrospinal fluid depending on the injury magnitude, and can also be found in blood stream because of a compromised blood-brain barrier. In this review, we examine the various factors that must be taken into account in the search for a reliable non-invasive biomarkers in traumatic brain injury and their role in the diagnosis and outcome evaluation.

Clinical utility of serum levels of ubiquitin C-terminal hydrolase as a biomarker for severe traumatic brain injury

BACKGROUND

Brain damage markers released in cerebrospinal fluid (CSF) and blood may provide valuable information about diagnosis and outcome prediction after traumatic brain injury (TBI).

OBJECTIVE

To examine the concentrations of ubiquitin C-terminal hydrolase-L1 (UCH-L1), a novel brain injury biomarker, in CSF and serum of severe TBI patients and their association with clinical characteristics and outcome.

METHODS

This case-control study enrolled 95 severe TBI subjects (Glasgow Coma Scale [GCS] score, 8). Using sensitive UCH-L1 sandwich ELISA, we studied the temporal profile of CSF and serum UCH-L1 levels over 7 days for severe TBI patients.

RESULTS

Comparison of serum and CSF levels of UCH-L1 in TBI patients and control subjects shows a robust and significant elevation of UCH-L1 in the acute phase and over the 7-day study period. Serum and CSF UCH-L1 receiver-operating characteristic curves further confirm strong specificity and selectivity for diagnosing severe TBI vs controls, with area under the curve values in serum and CSF statistically significant at all time points up to 24 hours (P < .001). The first 12-hour levels of both serum and CSF UCH-L1 in patients with GCS score of 3 to 5 were also significantly higher than those with GCS score of 6 to 8. Furthermore, UCH-L1 levels in CSF and serum appear to distinguish severe TBI survivors from nonsurvivors within the study, with nonsurvivors having significantly higher and more persistent levels of serum and CSF UCH-L1. Cumulative serum UCH-L1 levels > 5.22 ng/mL predicted death (odds ratio, 4.8).

CONCLUSION

Serum levels of UCH-L1 appear to have potential clinical utility in diagnosing TBI, including correlating to injury severity and survival outcome.

A literature review of the feasibility of glial fibrillary acidic protein as a biomarker for stroke and traumatic brain injury

Traumatic brain injuries (TBIs) are potentially lethal medical conditions, with symptoms that can overlap with symptoms of injuries outside the brain. In many cases, current diagnostic methods do not fully distinguish acute brain injury from other organ damage. In the management of stroke patients, the choice of treatment depends on whether the stroke is ischemic or hemorrhagic; however, no quick lab diagnostic tests are available to distinguish between the two types of strokes. As a result, patient triage, disposition, and patient management decisions may be delayed for patients with suspected TBI and stroke. Glial fibrillary acidic protein (GFAP), a brain-specific biomarker that is released into the blood following TBI and stroke, is being explored for potential diagnostic and prognostic value in these indications. We therefore conducted a review of MEDLINE-indexed publications from 2004 to 2011 to evaluate the current status of GFAP as a prognostic and diagnostic tool for TBI and stroke within the context of current published guidelines. Our review suggests that GFAP could provide clinically valuable information for the prognosis of TBI and stroke, but it is still at an early stage of development as a biomarker. Several TBI studies have shown elevated GFAP levels following a TBI event to be associated with greater severity of injury, poorer outcomes, and increased mortality. Clinical studies also indicate that GFAP has potential clinical utility in the differential diagnosis of various types of stroke. However, more clinical research will be required to determine the ability of GFAP levels to diagnose TBI in heterogeneous patient populations, as well as the ability of GFAP to differentiate between ischemic stroke (IS), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and non-stroke conditions in populations of patients with suspected rather than confirmed stroke. Additional clinical studies will also be required to define the temporal patterns of GFAP release in IS, ICH, SAH, and TBI, and their potential use in the differential diagnosis of these conditions. Finally, such research could demonstrate the ability of GFAP test results to provide unique clinical information that informs management decisions for TBI and stroke patients.

Serum biomarkers of neurologic injury in cardiac operations

Assessment of subtle neurocognitive decline after surgical procedures has been hampered by heterogeneous testing techniques and a lack of reproducibility. This review summarizes the sensitivity and specificity of biomarkers of neurologic injury to determine whether they can be applied in the postoperative period to accurately predict neurocognitive decline. Creatine kinase-brain type, neuron-specific enolase, and S100B can be released into serum during operations by extracranial sources. Glial fibrillary acidic protein is a sensitive marker, and there are extracranial sources that are antigenically different from the brain-derived form. Serum levels of tau protein after acute neurologic injury do not reliability correlate with incidence.

Activation of P2X7 promotes cerebral edema and neurological injury after traumatic brain injury in mice

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Cerebral edema, the abnormal accumulation of fluid within the brain parenchyma, contributes to elevated intracranial pressure (ICP) and is a common life-threatening neurological complication following TBI. Unfortunately, neurosurgical approaches to alleviate increased ICP remain controversial and medical therapies are lacking due in part to the absence of viable drug targets. In the present study, genetic inhibition (P2X7-/- mice) of the purinergic P2x7 receptor attenuated the expression of the pro-inflammatory cytokine, interleukin-1β (IL-1β) and reduced cerebral edema following controlled cortical impact, as compared to wild-type mice. Similarly, brilliant blue G (BBG), a clinically non-toxic P2X7 inhibitor, inhibited IL-1β expression, limited edemic development, and improved neurobehavioral outcomes after TBI. The beneficial effects of BBG followed either prophylactic administration via the drinking water for one week prior to injury or via an intravenous bolus administration up to four hours after TBI, suggesting a clinically-implementable therapeutic window. Notably, P2X7 localized within astrocytic end feet and administration of BBG decreased the expression of glial fibrillary acidic protein (GFAP), a reactive astrocyte marker, and attenuated the expression of aquaporin-4 (AQP4), an astrocytic water channel that promotes cellular edema. Together, these data implicate P2X7 as a novel therapeutic target to prevent secondary neurological injury after TBI, a finding that warrants further investigation.

Serum-based protein biomarkers in blast-induced traumatic brain injury spectrum disorder

The biological consequences of exposure to explosive blast are extremely complex. Serum protein biomarkers in blast-induced traumatic brain injury (bTBI) can aid in determining injury severity, monitoring progress, and predicting outcome. Exposure to blast results in varying degrees of physical injury. Explosive blast can also induce psychological stress that can contribute to or amplify the extent of physical damage. Given the complexity, scale of injury, and variety of symptoms, bTBI may be best described as a spectrum disorder. In this focused review, we summarize the status of serum protein biomarkers in bTBI in the context of the classification and pathological changes of other forms of TBI. Finally, we recommend specific and easily implementable measures to accelerate serum protein biomarker discovery and validation in bTBI.

Characterization of Antibodies that Detect Human GFAP after Traumatic Brain Injury

After traumatic brain injury (TBI), glial fibrillary acidic protein (GFAP) and other brain-derived proteins and their breakdown products are released into biofluids such as CSF and blood. Recently, a sandwich ELISA was constructed that measured GFAP concentrations in CSF or serum from human mild-moderate TBI patients. The goals of the present study were to characterize the same two antibodies used in this ELISA, and to determine which GFAP bands are detected by this antibody combination. Here, both antibodies recognized GFAP specifically in human brain and post-TBI CSF in a cluster of bands ranging from 50–38 kDa, that resembled bands from calpain-cleaved GFAP. By immunoprecipitation, the anti-GFAP Capture antibody recovered full length GFAP and its breakdown products from human brain lysate and post-TBI CSF. These findings demonstrate that the anti-GFAP ELISA antibodies non-preferentially detect intact GFAP and GFAP breakdown products, underscoring their utility for detecting brain injury in human patients.

Ability of S100B to predict severity and cranial CT results in children with TBI

OBJECTIVES

To evaluate the ability of S100B to predict severity of TBI and abnormal cranial CT results for children with TBI.

METHODS

This is a secondary analysis of a previously established cohort of consecutive patients presenting to the emergency department with TBI limited to children <19 years of age, who arrived within 6 hours of injury, received a cranial CT scan and consented to blood drawn for S100B.

RESULTS

A total of 109 children were included in this cohort. The mean S100B levels were higher in children with moderate/severe TBI as compared to children with mild TBI based GCS score (0.281 µg L(-1), 95%CI = 0.101, 0.461 vs 0.053, 95%CI = 0.010, 0.095). S100B levels were significantly elevated in children following TBI with abnormal cranial CT as compared to children with a normal cranial CT (0.210 µg L(-1), SD = 0.313 vs 0.036 µg L(-1), SD = 0.046, p = 0.03). Area under the curve for S100B was also significant (0.72, 95%CI = 0.58, 0.86) for prediction of abnormal cranial CT for children with TBI. S100B did not predict abnormal cranial CT for children following TBI with a GCS of 15 (AUC = 0.53, 95%CI = 0.36, 0.71).

CONCLUSIONS

For children following TBI, S100B appears to predict severity of TBI; however, it may not be clinically useful as an independent screening test to select children with mild TBI who need a cranial CT.

Multiple indicators model of long-term mortality in traumatic brain injury

OBJECTIVE

To examine the prognostic ability of protein S100B, neuron-specific enolase (NSE) and glial fibrillary acid protein (GFAP) for prediction of 1-year mortality in patients with traumatic brain injury (TBI) in relation to clinical and radiological characteristics of TBI.

METHODS

Brain injury was quantified in 84 patients (Glasgow Coma Scale [GCS] ≤ 12) using clinical (GCS, pupils), radiological (computed tomography [CT] classification and individual CT characteristics) and biochemical (S100B, NSE and GFAP) data at admission and in the acute post-injury period.

RESULTS

Initial and peak S100B, NSE and GFAP concentrations were higher in non-survivors (n = 26) than in survivors (p-value range: <0.001-0.018). Cox regression showed that GFAP and S100B concentration and the temporal profile of S100B were more powerful independent predictors of mortality than baseline clinical and radiological characteristics or clinical and radiological indicators of neurological deterioration. The prognostic models containing admission variables and those available during the subsequent clinical course showed the same discrimination ability (area under receiver characteristic curve 0.92), but the model based on variables available in the acute post-injury period calibrated better (p = 0.428).

CONCLUSION

Mortality at 1-year post-TBI is accurately predicted by the combination of GFAP and S100B concentration and clinical and radiological characteristics at admission or in the acute post-injury period.

Depletion of GR-1-Positive Cells Is Associated with Reduced Neutrophil Inflammation and Astrocyte Reactivity after Experimental Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is the stroke subtype with the highest mortality and morbidity with 25% of patients dying within the first 48 h and a high incidence of poor outcomes. Because of high early mortality rates, an understanding of acute brain injury mechanisms is essential. In this study, we have investigated the putative role of acute inflammation in brain injury after experimental ICH. We depleted GR-1(+) cells in mice by intraperitoneal administration of anti-GR-1 antibody or normal rat serum (control). We then induced ICH by infusion of autologous whole blood into the striatum and compared functional outcome and brain injury markers between the two groups. We found that administration of anti-GR-1 antibody led to a profound decrease in circulating GR-1(+) cells (1.5 ± 0.34% vs. 50.3 ± 8.3% of CD45(+) cells, p ≤ 0.01) and that brain neutrophils decreased by approximately 50% (p ≤ 0.05). We observed a reduction in astrocyte immunoreactivity in the GR-1(+) cell-depleted group (p ≤ 0.05). Conversely, we did not find attenuation of brain edema or differences in behavioral deficits between the two groups. In summary, our results are promising and suggest that larger studies or different neutrophil manipulations may produce greater attenuation of injury after ICH.

Brain injury biomarkers may improve the predictive power of the IMPACT outcome calculator

Outcome prediction following severe traumatic brain injury (sTBI) is a widely investigated field of research. A major breakthrough is represented by the IMPACT prognostic calculator based on admission data of more than 8500 patients. A growing body of scientific evidence has shown that clinically meaningful biomarkers, including glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCH-L1), and αII-spectrin breakdown product (SBDP145), could also contribute to outcome prediction. The present study was initiated to assess whether the addition of biomarkers to the IMPACT prognostic calculator could improve its predictive power. Forty-five sTBI patients (GCS score≤8) from four different sites were investigated. We utilized the core model of the IMPACT calculator (age, GCS motor score, and reaction of pupils), and measured the level of GFAP, UCH-L1, and SBDP145 in serum and cerebrospinal fluid (CSF). The forecast and actual 6-month outcomes were compared by logistic regression analysis. The results of the core model itself, as well as serum values of GFAP and CSF levels of SBDP145, showed a significant correlation with the 6-month mortality using a univariate analysis. In the core model, the Nagelkerke R(2) value was 0.214. With multivariate analysis we were able to increase this predictive power with one additional biomarker (GFAP in CSF) to R(2)=0.476, while the application of three biomarker levels (GFAP in CSF, GFAP in serum, and SBDP145 in CSF) increased the Nagelkerke R(2) to 0.700. Our preliminary results underline the importance of biomarkers in outcome prediction, and encourage further investigation to expand the predictive power of contemporary outcome calculators and prognostic models in TBI.

Use of serum biomarkers to predict cerebral hypoxia after severe traumatic brain injury

The management of severe traumatic brain injury (TBI) focuses on prevention and treatment of secondary insults such as cerebral hypoxia (CH). There are a number of biomarkers that are thought to play a part in secondary injury following severe TBI. This study evaluates the association between S100β, neuron-specific enolase (NSE), and glial fibrillary acidic protein (GFAP), detected in the serum of severe TBI patients and CH as measured by brain tissue oxygen partial pressure (Pbo(2)). Patients with severe TBI were prospectively enrolled. Pressure times time (PTD; mm Hg*h), measuring the depth and duration of CH, was calculated for 12-h periods for episodes of moderate (Pbo(2) < 20 mm Hg) and severe (Pbo(2) < 15 mm Hg) CH, and compared to serum levels of S100β, NSE, and GFAP drawn prior to periods of monitoring. An adjusted mixed model analysis was applied as was receiver operating characteristic (ROC) curve analysis. Of 76 patients enrolled, 24 had Pbo(2) monitoring. One hundred and thirty serum samples were matched with 12-h periods of monitoring. Significant associations were found in adjusted analyses between increasing serum levels of S100β (coefficient=0.57, 0.56; p<0.001), NSE (coefficient=0.48, 0.52; p<0.001), and GFAP (coefficient=0.29, 0.30; p=0.003 and 0.002), and increasing PTD of moderate (Pbo(2)<20 mm Hg) and severe (Pbo(2)<15 mm Hg) CH. AUCs for the prediction of moderate and severe CH were 0.62 and 0.66 for S100β, 0.55 and 0.71 for NSE, and 0.50 and 0.62 for GFAP, respectively. Specificities were between 76% and 90% for S100β and NSE. S100β, NSE, and GFAP demonstrate promise as candidate serum markers of impending CH. The fact that these biomarker elevations occur prior to the onset of clinical manifestations suggests that we may be able to predict imminent events following TBI. Given the morbidity of CH, early intervention and prevention may have a significant impact on outcomes and help guide decisions about the timing of interventions.

The usefulness of S100B, NSE, GFAP, NF-H, secretagogin and Hsp70 as a predictive biomarker of outcome in children with traumatic brain injury

BACKGROUND

Predicting the long-term outcome after traumatic brain injury (TBI) is an important component of treatment strategy. Despite dramatically improved emergency management of TBI and apparent clinical recovery, most patients with TBI still may have long-term central nervous system (CNS) impairment.

METHODS

Sixty-three patients with TBI were enrolled into the prospective study. Venous blood samples were taken at admission and every 24 h for a maximum of 6 consecutive days. Serum concentrations of the biomarkers S100B, neuron-specific enolase (NSE), GFAP, NF-H, secretagogin and Hsp70 were quantified immuno-luminometrically or by enzyme-linked immunosorbent assay. The outcome was evaluated 6 months after TBI using the Glasgow Outcome Scale (GOS) in all patients.

RESULTS

The S100B levels in patients with worse outcome (GOS 4 or death) were already significantly higher at D0 (p < 0.001; p = 0.002). NSE levels were significantly higher in patients who died or had worse outcomes (p < 0.001; p = 0.003). Patients who had worse outcomes (GOS) or died had higher GFAP values (p < 0.001; p < 0.001), but their dynamics were similar over the same period. NF-H grew significantly faster in patients who had a worse GOS or died (p < 0.001; p = 0.001).

CONCLUSIONS

Although further prospective study is warranted, these findings suggest that levels of biomarkers correlate with mortality and may be useful as predictors of outcome in children with TBI.

Translating biomarkers research to clinical care: applications and issues for rehabilomics

Traumatic brain injury is a leading cause of morbidity and mortality in adults and children in the United States. Despite steady improvement in our understanding of the pathophysiology of acquired brain injuries, there has been remarkably little improvement in brain injury therapies and/or pharmacologic treatments over the past decade. One of the reasons may be the inability to properly stratify subjects for clinical trials and/or to have real-time assessment of the effectiveness of a given intervention. It has been recognized for several decades that serum biomarkers may allow for more objective subject stratification as well as act as surrogate markers of treatment efficacy. Despite numerous studies, however, biomarkers are not currently part of clinical practice in either acquired brain injury or other neurologic or musculoskeletal disorders. The goals of this review article, therefore, are to use traumatic brain injury as a example to discuss the use of biomarkers in clinical and randomized controlled trials; to briefly discuss the field of neuroproteomics and its interface with neurologic interventions; and to provide an overview of the collaborative pathway between academia and industry, which needs to be an integral part of the translation of biomarkers from the bench to the bedside in any clinical population. Introduction of the concept of rehabilomics and implications of biomarker use for the physical medicine and rehabilitation physician also are discussed.

Dynamics of glial fibrillary acidic protein during traumatic brain injury in children

BACKGROUNDS

Glial fibrillary acidic protein (GFAP) is a monomeric intermediate filament protein found in the astroglial cytoskeleton and is not found outside the central nervous system. It is a brain-specific protein that is released after traumatic brain injury (TBI).

METHODS

This prospective study enrolled 59 children who had TBI, as verified by computed tomography. Daily GFAP measurement began at admission (<12 hours after trauma) and continued for 6 days. Blood samples were analyzed for GFAP by enzyme-linked immunosorbent assay. Outcome was assessed using the Glasgow Outcome Scale (GOS) at 6 months after injury.

RESULTS

The median serum levels of GFAP at admission were 7.47 ng/mL in patients who died, compared with 0.12 ng/mL in patients who survived (p=0.002). GFAP levels were significantly higher in patients who had a poor outcome 6 months after injury than in those who were alive or had good outcome (p<0.001). The area under the receiver operating characteristic curve for GFAP was 0.833 for day 0 and 0.884 for day 2.

CONCLUSIONS

These results suggest that determination of serum levels of GFAP may add to the clinical assessment of the primary damage and prediction of outcome after severe TBI.

Neuron-specific enolase, S100B, and glial fibrillary acidic protein levels as outcome predictors in patients with severe traumatic brain injury

BACKGROUND

The availability of markers able to provide an early insight related to prognostic and functional outcome of patients with traumatic brain injury (TBI) are limited.

OBJECTIVE

The relationship of clinical outcome with CSF neuron-specific enolase (NSE), S100B and glial fibrillary acidic protein (GFAP) levels in patients with severe TBI was investigated.

METHODS

Twenty patients with severe TBI (7 days at unit care) and controls were studied. Patients were grouped according to the outcome: (1) nonsurvival (n=5): patients who died; (2) survival A (n=15): CSF sampled between 1st and 3rd day from patients who survived after hospital admission; and (3) survival B (n=7): CSF sampled between 4th and 7th day from patients who survived after hospital admission and were maintained with intraventricular catheter up to 7 days.

RESULTS

Up to 3 days, S100B and NSE levels (ng/mL) were significantly elevated in the nonsurvival compared with survival A group (S100: 12.45 ± 5.46 vs 5.64 ± 3.36; NSE: 313.20 ± 45.51 vs 107.80 ± 112.10). GFAP levels did not differ between groups. In the survival B group S100B, GFAP, and NSE levels were still elevated compared with control (4.59 ± 2.19, 2.48 ± 2.55, and 89.80 ± 131.10, respectively). To compare S100B and NSE for the prediction of nonsurvival and survival patients we performed receiver operating characteristic curves. At admission, CSF NSE level predicts brain death more accurately than S100B.

CONCLUSION

Early elevations (up to 3 days) of S100B and NSE secondary to severe TBI predict deterioration to brain death. However, this feature was more prominently associated with NSE than S100B.

Elevated levels of serum glial fibrillary acidic protein breakdown products in mild and moderate traumatic brain injury are associated with intracranial lesions and neurosurgical intervention

STUDY OBJECTIVE

This study examines whether serum levels of glial fibrillary acidic protein breakdown products (GFAP-BDP) are elevated in patients with mild and moderate traumatic brain injury compared with controls and whether they are associated with traumatic intracranial lesions on computed tomography (CT) scan (positive CT result) and with having a neurosurgical intervention.

METHODS

This prospective cohort study enrolled adult patients presenting to 3 Level I trauma centers after blunt head trauma with loss of consciousness, amnesia, or disorientation and a Glasgow Coma Scale (GCS) score of 9 to 15. Control groups included normal uninjured controls and trauma controls presenting to the emergency department with orthopedic injuries or a motor vehicle crash without traumatic brain injury. Blood samples were obtained in all patients within 4 hours of injury and measured by enzyme-linked immunosorbent assay for GFAP-BDP (nanograms/milliliter).

RESULTS

Of the 307 patients enrolled, 108 were patients with traumatic brain injury (97 with GCS score 13 to 15 and 11 with GCS score 9 to 12) and 199 were controls (176 normal controls and 16 motor vehicle crash controls and 7 orthopedic controls). Receiver operating characteristic curves demonstrated that early GFAP-BDP levels were able to distinguish patients with traumatic brain injury from uninjured controls with an area under the curve of 0.90 (95% confidence interval [CI] 0.86 to 0.94) and differentiated traumatic brain injury with a GCS score of 15 with an area under the curve of 0.88 (95% CI 0.82 to 0.93). Thirty-two patients with traumatic brain injury (30%) had lesions on CT. The area under these curves for discriminating patients with CT lesions versus those without CT lesions was 0.79 (95% CI 0.69 to 0.89). Moreover, the receiver operating characteristic curve for distinguishing neurosurgical intervention from no neurosurgical intervention yielded an area under the curve of 0.87 (95% CI 0.77 to 0.96).

CONCLUSION

GFAP-BDP is detectable in serum within an hour of injury and is associated with measures of injury severity, including the GCS score, CT lesions, and neurosurgical intervention. Further study is required to validate these findings before clinical application.