Soluble adhesion molecules in CSF are increased in children with severe head injury

Pediatric Neurocritical Care: Maximizing Neurodevelopmental Outcomes Through Specialty Care

The field of pediatric neurocritical care (PNCC) has expanded and evolved over the last three decades. As mortality from pediatric critical care illness has declined, morbidity from neurodevelopmental disorders has expanded. PNCC clinicians have adopted a multidisciplinary approach to rapidly identify neurological injury, implement neuroprotective therapies, minimize secondary neurological insults, and establish transitions of care, all with the goal of improving neurocognitive outcomes for their patients. Although there are many aspects of PNCC and adult neurocritical care (NCC) medicine that are similar, elemental difference between adult and pediatric medicine has contributed to a divergent evolution of the respective fields. The low incidence of pediatric critical care illness, the heterogeneity of neurological insults, and the limited availability of resources all shape the need for a PNCC clinical care model that is distinct from the established paradigm adopted by the adult neurocritical care community at large. Considerations of neurodevelopment are fundamental in pediatrics. When neurological injury occurs in a child, the neurodevelopmental stage at the time of insult alters the impact of the neurological disease. Developmental variables contribute to a range of outcomes for seemingly similar injuries. Despite the relative infancy of the field of PNCC, early reports have shown that implementation of a specialized PNCC service elevates the quality and safety of care, promotes education and communication, and improves outcomes for children with acute neurological injuries. The multidisciplinary approach of PNCC clinicians and researchers also promotes a culture that emphasizes the importance of quality improvement and education initiatives, as well as development of and adherence to evidence-based guidelines and family-focused care models.

Mesenchymal stromal cell secretome for traumatic brain injury: Focus on immunomodulatory action

The severity and long-term consequences of brain damage in traumatic brain injured (TBI) patients urgently calls for better neuroprotective/neuroreparative strategies for this devastating disorder. Mesenchymal stromal cells (MSCs) hold great promise and have been shown to confer neuroprotection in experimental TBI, mainly through paracrine mechanisms via secreted bioactive factors (i.e. secretome), which indicates significant potential for a cell-free neuroprotective approach. The secretome is composed of cytokines, chemokines, growth factors, proteins, lipids, nucleic acids, metabolites, and extracellular vesicles; it may offer advantages over MSCs in terms of delivery, safety, and variability of therapeutic response for brain injury. Immunomodulation by molecular factors secreted by MSCs is considered to be a key mechanism involved in their multi-potential therapeutic effects. Regulated neuroinflammation is required for healthy remodeling of central nervous system during development and adulthood. Moreover, immune cells and their secreted factors can also contribute to tissue repair and neurological recovery following acute brain injury. However, a chronic and maladaptive neuroinflammatory response can exacerbate TBI and contribute to progressive neurodegeneration and long-term neurological impairments. Here, we review the evidence for MSC-derived secretome as a therapy for TBI. Our framework incorporates a detailed analysis of in vitro and in vivo studies investigating the effects of the secretome on clinically relevant neurological and histopathological outcomes. We also describe the activation of immune cells after TBI and the immunomodulatory properties exerted by mediators released in the secretome. We then describe how ageing modifies central and systemic immune responses to TBI and discuss challenges and opportunities of developing secretome based neuroprotective therapies for elderly TBI populations. Finally, strategies aimed at modulating the secretome in order to boost its efficacy for TBI will also be discussed.

Promising candidate cerebrospinal fluid biomarkers of seizure disorder, infection, inflammation, tumor, and traumatic brain injury in pediatric patients

Cerebrospinal fluid (CSF) is a dynamic metabolically active body fluid that has many important roles and is commonly analyzed in pediatric patients, mainly to diagnose central nervous system infection and inflammation disorders. CSF components have been extensively evaluated as biomarkers of neurological disorders in adult patients. Circulating microRNAs in CSF are a promising class of biomarkers for various neurological diseases. Due to the complexity of pediatric neurological disorders and difficulty in acquiring CSF samples from pediatric patients, there are challenges in developing CSF biomarkers of pediatric neurological disorders. This review aimed to provide an overview of novel CSF biomarkers of seizure disorders, infection, inflammation, tumor, traumatic brain injuries, intraventricular hemorrhage, and congenital hydrocephalus exclusively observed in pediatric patients.

Protein biomarkers of epileptogenicity after traumatic brain injury

Traumatic brain injury (TBI) is a major risk factor for acquired epilepsy. Post-traumatic epilepsy (PTE) develops over time in up to 50% of patients with severe TBI. PTE is mostly unresponsive to traditional anti-seizure treatments suggesting distinct, injury-induced pathomechanisms in the development of this condition. Moderate and severe TBIs cause significant tissue damage, bleeding, neuron and glia death, as well as axonal, vascular, and metabolic abnormalities. These changes trigger a complex biological response aimed at curtailing the physical damage and restoring homeostasis and functionality. Although a positive correlation exists between the type and severity of TBI and PTE, there is only an incomplete understanding of the time-dependent sequelae of TBI pathobiologies and their role in epileptogenesis. Determining the temporal profile of protein biomarkers in the blood (serum or plasma) and cerebrospinal fluid (CSF) can help to identify pathobiologies underlying the development of PTE, high-risk individuals, and disease modifying therapies. Here we review the pathobiological sequelae of TBI in the context of blood- and CSF-based protein biomarkers, their potential role in epileptogenesis, and discuss future directions aimed at improving the diagnosis and treatment of PTE.

Brain region and epilepsy-associated differences in inflammatory mediator levels in medically refractory mesial temporal lobe epilepsy

Background

Epilepsy patients have distinct immune/inflammatory cell profiles and inflammatory mediator levels in the blood. Although the neural origin of inflammatory cells and mediators has been implied, few studies have measured these inflammatory components in the human brain itself. This study examines the brain levels of chemokines (8), cytokines (14), and vascular injury mediators (3) suspected of being altered in epilepsy.

Methods

Soluble protein extracts of fresh frozen resected hippocampus, entorhinal cortex, and temporal cortex from 58 medically refractory mesial temporal lobe epilepsy subjects and 4 nonepileptic neurosurgical subjects were assayed for 25 inflammation-related mediators using ultrasensitive low-density arrays.

Results

Brain mediator levels were compared between regions and between epileptic and nonepileptic cases, showing a number of regional and possible epilepsy-associated differences. Eotaxin, interferon-γ, interleukin (IL)-2, IL-4, IL-12 p70, IL-17A, tumor necrosis factor-α, and intercellular adhesion molecule (ICAM)-1 levels were highest in the hippocampus, the presumptive site of epileptogenesis. Surprisingly, IL-1β and IL-1α were lowest in the hippocampus, compared to cortical regions. In the temporal cortex, IL-1β, IL-8, and MIP-1α levels were highest, compared to the entorhinal cortex and the hippocampus.

The most pronounced epilepsy-associated differences were decreased levels of eotaxin, IL-1β, C-reactive protein, and vascular cell adhesion molecule (VCAM)-1 and increased IL-12 p70 levels. Caution must be used in interpreting these results, however, because nonepileptic subjects were emergent neurosurgical cases, not a control group.

Correlation analyses of each mediator in each brain region yielded valuable insights into the regulation of these mediator levels in the brain. Over 70 % of the associations identified were between different mediators in a single brain region, providing support for local control of mediator levels. Correlations of different mediators in different brain regions suggested more distributed control mechanisms, particularly in the hippocampus. Interestingly, only four mediators showed robust correlations between the brain regions, yet levels in three of these were significantly different between regions, indicating both global and local controls for these mediators.

Conclusions

Both brain region-specific and epilepsy-associated changes in inflammation-related mediators were detected. Correlations in mediator levels within and between brain regions indicated local and global regulation, respectively. The hippocampus showed the majority of interregional associations, suggesting a focus of inflammatory control between these regions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0727-z) contains supplementary material, which is available to authorized users.

The immune system in traumatic brain injury

Traumatic brain injury (TBI) is the major cause of death in children and young adults and one of the major reasons for long-term disability worldwide, however, no specific clinical treatment option could be established so far. This is surprising since it is well known that following the initial mechanical damage to the brain a plethora of delayed processes are activated which ultimately result in additional brain damage. Among these secondary mechanisms, acute and chronic activation of the innate and adaptive immune system is increasingly believed to play an important role for the pathogenesis of TBI. Understanding these processes may results in new, clinically applicable therapeutic options for TBI patients.

Cerebrospinal Fluid Markers of Macrophage and Lymphocyte Activation After Traumatic Brain Injury in Children

OBJECTIVES

The magnitude and role of the cellular immune response following pediatric traumatic brain injury remains unknown. We tested the hypothesis that macrophage/microglia and T-cell activation occurs following pediatric traumatic brain injury by measuring cerebrospinal fluid levels of soluble cluster of differentiation 163 and ferritin and soluble interleukin-2 receptor α, respectively, and determined whether these biomarkers were associated with relevant clinical variables and outcome.

DESIGN

Retrospective analysis of samples from an established, single-center cerebrospinal fluid bank.

SETTING

PICU in a tertiary children's hospital.

PATIENTS

Sixty-six pediatric patients after severe traumatic brain injury (Glasgow Coma Scale score < 8) who were 1 month to 16 years old and 17 control patients who were 1 month to 14 years old.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cerebrospinal fluid levels of soluble cluster of differentiation 163, ferritin, and soluble interleukin-2 receptor α were determined by enzyme-linked immunosorbent assay at two time points (t1 = 17 ± 10 hr; t2 = 72 ± 15 hr) for each traumatic brain injury patient. Cerebrospinal fluid levels of soluble cluster of differentiation 163, ferritin, and soluble interleukin-2 receptor α after traumatic brain injury were compared with controls and analyzed for associations with age, patient sex, initial Glasgow Coma Scale score, diagnosis of abusive head trauma, the presence of hemorrhage on CT scan, and Glasgow Outcome Scale score. Cerebrospinal fluid level of soluble cluster of differentiation 163 was increased in traumatic brain injury patients at t2 versus t1 and controls (median, 95.4 ng/mL [interquartile range, 21.8-134.0 ng/mL] vs 31.0 ng/mL [5.7-77.7 ng/mL] and 27.8 ng/mL [19.1-43.1 ng/mL], respectively; p < 0.05). Cerebrospinal fluid level of ferritin was increased in traumatic brain injury patients at t2 and t1 versus controls (8.3 ng/mL [<7.5-19.8 ng/mL] and 8.9 ng/mL [<7.5-26.7 ng/mL] vs <7.5 ng/mL below lower limit of detection, respectively; p < 0.05). Cerebrospinal fluid levels of soluble interleukin-2 receptor α in traumatic brain injury patients at t2 and t1 were not different versus controls. Multivariate regression revealed associations between high ferritin and age 4 years or younger, lower Glasgow Coma Scale score, abusive head trauma, and unfavorable Glasgow Outcome Scale score.

CONCLUSIONS

Children with traumatic brain injury demonstrate evidence for macrophage activation after traumatic brain injury, and in terms of cerebrospinal fluid ferritin, this appears more prominent with young age, initial injury severity, abusive head trauma, and unfavorable outcome. Further study is needed to determine whether biomarkers of macrophage activation may be used to discriminate between aberrant and adaptive immune responses and whether inflammation represents a therapeutic target after traumatic brain injury.

Selectins and their ligands as potential immunotherapeutic targets in neurological diseases

Selectins are a family of adhesion receptors that bind to highly glycosylated molecules expressed on the surface of leukocytes and endothelial cells. The interactions between selectins and their ligands control tethering and rolling of leukocytes on the vascular wall during the process of leukocyte migration into the tissues under physiological and pathological conditions. In recent years, it has been shown that leukocyte recruitment in the CNS plays a pivotal role in diseases such as multiple sclerosis, ischemic stroke, epilepsy and traumatic brain injury. In this review, we discuss the role of selectins in leukocyte–endothelial interactions in the pathogenesis of neurological diseases, highlighting new findings suggesting that selectins and their ligands may represent novel potential therapeutic targets for the treatment of CNS diseases.

Delayed neurovascular inflammation after mild traumatic brain injury in rats

INTRODUCTION

Experimental traumatic brain injury (TBI) elicits acute local inflammatory responses, including up-regulation of adhesion molecules and neutrophils in the injured brain. However, in clinical experiences there were at least three types of TBI, which included mild, moderate and severe types, and there would be different neuroinflammatory responses. This study investigated the inflammatory responses after mild TBI in rats.

METHODS

Adult male Sprague-Dawley rats (n = 40) were group-housed and injured using an impact method. Motor function was assessed 1-4 days after the injury by using a grip test (Grip strength meter; Singa). Blood samples collected from the rats before the injury and after the injury and the Intercellular adhesion molecule-1 (ICAM-1) level were measured.

RESULTS

The ICAM-1 expression from pre-injury to post-injury showed a significantly greater gradual elevation in the rats in the mild-injury group than in the moderate-injury group. The neurological function evaluated with grip test showed no deterioration of neurological function in the mild-injury group but gradual deterioration in the moderate-injury group.

CONCLUSION

These findings showed a delayed inflammatory reaction in the mild-injury group without progressive deterioration of neurological function. Therefore, in the moderate-injury group, no progression phase was observed.

Systematic review of clinical research on biomarkers for pediatric traumatic brain injury

Abstract The objective was to systematically review the medical literature and comprehensively summarize clinical research performed on biomarkers for pediatric traumatic brain injury (TBI) and to summarize the studies that have assessed serum biomarkers acutely in determining intracranial lesions on CT in children with TBI. The search strategy included a literature search of PubMed,(®) MEDLINE,(®) and the Cochrane Database from 1966 to August 2011, as well as a review of reference lists of identified studies. Search terms used included pediatrics, children, traumatic brain injury, and biomarkers. Any article with biomarkers of traumatic brain injury as a primary focus and containing a pediatric population was included. The search initially identified 167 articles. Of these, 49 met inclusion and exclusion criteria and were critically reviewed. The median sample size was 58 (interquartile range 31-101). The majority of the articles exclusively studied children (36, 74%), and 13 (26%) were studies that included both children and adults in different proportions. There were 99 different biomarkers measured in these 49 studies, and the five most frequently examined biomarkers were S100B (27 studies), neuron-specific enolase (NSE) (15 studies), interleukin (IL)-6 (7 studies), myelin basic protein (MBP) (6 studies), and IL-8 (6 studies). There were six studies that assessed the relationship between serum markers and CT lesions. Two studies found that NSE levels ≥15 ng/mL within 24 h of TBI was associated with intracranial lesions. Four studies using serum S100B were conflicting: two studies found no association with intracranial lesions and two studies found a weak association. The flurry of research in the area over the last decade is encouraging but is limited by small sample sizes, variable practices in sample collection, inconsistent biomarker-related data elements, and disparate outcome measures. Future studies of biomarkers for pediatric TBI will require rigorous and more uniform research methodology, common data elements, and consistent performance measures.

Cell adhesion molecules in Alzheimer's disease

Cell adhesion molecules (CAMs) mediate interactions between cells and their surroundings that are vital to processes controlling for cell survival, activation, migration, and plasticity. However, increasing evidence suggests that CAMs also mediate mechanisms involved in several neurological diseases. This article reviews the current knowledge on the role of CAMs in amyloid-β (Aβ) metabolism, cell plasticity, neuroinflammation, and vascular changes, all of which are considered central to the pathogenesis and progression of Alzheimer's disease (AD). This paper also outlines the possible roles of CAMs in current and novel AD treatment strategies.

Guilty molecules, guilty minds? The conflicting roles of the innate immune response to traumatic brain injury

Traumatic brain injury (TBI) is a complex disease in the most complex organ of the body, whose victims endure lifelong debilitating physical, emotional, and psychosocial consequences. Despite advances in clinical care, there is no effective neuroprotective therapy for TBI, with almost every compound showing promise experimentally having disappointing results in the clinic. The complex and highly interrelated innate immune responses govern both the beneficial and deleterious molecular consequences of TBI and are present as an attractive therapeutic target. This paper discusses the positive, negative, and often conflicting roles of the innate immune response to TBI in both an experimental and clinical settings and highlights recent advances in the search for therapeutic candidates for the treatment of TBI.

Mechanisms and consequences of acquired brain injury during development

The brain of the infant and young child is a developing, dynamic, structure subject to functional remodelling under the influence of factors responsible for optimal neuronal development and synaptogenesis. It exhibits age dependent variation in metabolic rate, blood flow, and ability to tolerate oxidative stress. It is also characterized by an exuberance of neurotransmitter activity, particularly in the first few years of life. The dynamic evolution and adaptability of early brain function permits the organization of neuronal networks to be influenced by environmental stimulation, and, to reduce the functional impact of injury. However, these same processes may also exacerbate the harm sustained by the brain following an acquired brain injury (ABI). The developing neurons are susceptible to excitotoxicity, oxidative stress, and, inflammation, often leading to cellular necrosis and apoptosis. Despite being immunologically privileged via the blood brain barrier, the developing brain is susceptible to injury from systemic inflammation through alteration of normally protective cerebrovascular endothelial cell function. Finally, many of the therapeutic agents currently employed in post-ABI hospital care may also compromise ABI outcome via non-intended pharmacological effects. These agents include analgesic, sedative and anti-convulsant medications. This review emphasizes those physiological considerations in the developing brain which may impact the outcome after ABI, including, the cellular mechanisms of neuronal and cerebrovascular endothelial cell injury, ABI outcome and future therapeutic directions.

Combining coma score and serum biomarker levels to predict unfavorable outcome following childhood brain trauma

This study aims to determine if pairing the Glasgow Coma Scale (GCS) with serum biomarker levels may achieve higher outcome predictive values than using either the GCS or biomarker levels alone in childhood brain trauma. Twenty-eight critically ill children with isolated accidental brain trauma were studied in a prospective observational study. The GCS was recorded at various time points post injury. Enzyme-linked immunosorbent assay (ELISA) was used to quantify eight different serum biomarker levels (S100b, NSE, IL-6, IL-8, IL-10, L-selectin, SICAM, and endothelin) on day 1 post injury. The Glasgow Outcome Score (GOS) was used to assess global outcome at 6 months post injury. Outcome predictive values of the GCS, individual biomarker levels, and paired combinations of the GCS and biomarkers were compared using receiver operator characteristic (ROC) curve analysis and its multivariate extension, multivariate ROC curve (MultiROC). When using either the GCS or individual biomarker levels alone to predict unfavorable outcome, only the PICU discharge summated GCS achieved an area under the ROC curve (AUC) of more than 0.95. This high degree of outcome predictability was also achieved by pairing the GCS with a single biomarker level. The most pronounced improvement in outcome prediction was observed by pairing the post-resuscitation summated GCS with the day-1 serum IL-8 level, which increased the AUC from 0.78 to 0.98 and the sensitivity and specificity from 75% to 100% and 96% respectively. Paired combinations of the GCS and serum biomarker levels greatly enhanced the accuracy of post-traumatic unfavorable outcome prediction than may be achieved using either the GCS or individual biomarker levels alone.

Pediatric brain trauma outcome prediction using paired serum levels of inflammatory mediators and brain-specific proteins

Many potential brain trauma biomarkers have been reported, but no previous study has described outcome prediction using combinations of biomarker levels. We aimed to investigate the outcome predictive values of multiple biomarkers from different mediator families and to determine whether combinations of two serum biomarkers may achieve higher outcome predictive values than individual biomarker levels. A prospective observational study was conducted involving 28 children requiring intensive care management following brain trauma. Day 1 post-injury serum concentrations of eight different biomarkers--S100b protein (S100b), neuron-specific enolase (NSE), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), soluble intracellular adhesion molecule (SICAM), L-selectin, and endothelin--were quantified using enzyme-linked immunosorbent assay (ELISA). Global outcome was assessed at 6 months post-injury using the Glasgow Outcome Score (GOS). Receiver operator characteristic curve (ROC) analysis and its multivariate extension, Multivariate ROC (MultiROC), were used to assess the outcome predictive values of the individual and the paired biomarkers. None of the eight biomarkers assessed individually achieved an area under the ROC curve (AUC) of more than 0.95 for predicting unfavorable outcome, but five of the 20 biomarker pairs assessed had this high degree of outcome predictability. Two combinations using S100b as the "screening marker" and either L-selectin or IL-6 as the "varying marker" achieved an AUC of 0.98, and their specificity and sensitivity for unfavorable outcome prediction were 96% and 100%, respectively. Prognostic pairs combining serum levels of two biomarkers (inflammatory mediators and brain-specific proteins) offer better outcome predictive values for unfavorable outcome after childhood brain trauma than may be achieved using individual marker levels.

Clinical management and functional neuromonitoring in traumatic brain injury in children

PURPOSE OF REVIEW

Traumatic brain injury is the main cause of childhood disability and death. In this review, we highlight recent original findings and emerging themes from published literature on children with serious traumatic brain injury.

RECENT FINDINGS

We focus this review on lessons learned from our recent randomized clinical trial of hypothermia therapy in severe traumatic brain injury in children and on bedside neuromonitoring. We propose that integrating the measurement of biomarkers into clinical care as surrogate endpoints and as potential prognostic markers would allow us to evaluate earlier the effect of injury and clinical care in children after traumatic brain injury. Several methods are now more readily available to monitor cerebral physiology in children. These methods include indices evaluating the integrity of cerebral autoregulation, such as the pressure reactivity index derived from values obtained from intracranial pressure measurements, flow velocity measurements from transcranial Doppler ultrasonography or from cerebral oximetry. Other methods allow the evaluation of coma with the nonlinear analysis of electroencephalography or the evaluation of cerebral metabolism and cell death pathways with biomarkers from serum, cerebral spinal fluid, and cerebral microdialysis.

SUMMARY

We suggest expanding clinical functional neuromonitoring to help clinicians understand the burden of exposure to physiological variables and response to therapies during intensive care in order to enhance the management of critically ill children with traumatic brain injury.

Molecular mechanisms of traumatic brain injury in children. A review

Despite advances in molecular biology and genetics, the precise pathophysiology of traumatic brain injury (TBI) in children is unknown. In this paper the authors review what is currently known about intra- and extracellular responses to pediatric TBI and relate these factors to future investigations. Although hyperemia and vascular congestion have long been thought to be the hallmarks of pediatric TBI, on a cellular level, calcium influx as well as modulation of local neurotransmitters appears to play a major role in its onset. Recent genetic and proteomic research has identified specific neurotrophic factors as well as apoptotic and antiapoptotic genes that appear to control the progression of inflammation and neuronal damage. The search for a therapeutic target will ultimately require a thorough understanding of these factors and their interplay on a proteomic, genomic, and neuromic level.

Biomarkers in the clinical diagnosis and management of traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of death and disability among young adults. Numerous safety improvements in the workplace, the addition of airbags to vehicles, and the enforcement of speed limits have all helped to reduce the incidence and severity of head trauma. While improvements in emergency response times and acute care have increased TBI survivability, this has heightened the necessity for developing reliable methods to identify patients at risk of developing secondary pathologies. At present, the primary clinical indicators for the presence of brain injury are the Glasgow Coma Scale (GCS), pupil reactivity, and head computed tomography (CT). While these indices have proven useful for stratifying the magnitude and extent of brain damage, they have limited utility for predicting adverse secondary events or detecting subtle damage. Biomarkers, reflecting a biological response to injury or disease, have proven useful for the diagnosis of many pathological conditions including cancer, heart failure, infection, and genetic disorders. For TBI, several proteins synthesized in astroglial cells or neurons have been proposed as potential biomarkers. These proteins include the BB isozyme of creatine kinase (CK-BB, predominant in brain), glial fibrilary acidic protein (GFAP), myelin basic protein (MBP), neuron-specific enolase (NSE), and S100B.The presence of these biomarkers in the cerebrospinal fluid and serum of patients with moderate-to-severe TBI, and their correlation with outcome, suggest that they may have utility as surrogate markers in clinical trials. In addition, many of these markers have been found to be sensitive indicators of injury, and therefore may have the potential to diagnose persons with mild TBI. In addition to biomarkers that correlate with long-term outcome, a few studies have identified prognostic biomarkers for secondary injury that may be useful in individualizing patient management.

Multiplex assessment of serum biomarker concentrations in well-appearing children with inflicted traumatic brain injury

Proper diagnosis of mild inflicted traumatic brain injury (ITBI) is difficult; children often present without a history of trauma and with nonspecific symptoms, such as vomiting. Previous studies suggest that biomarkers may be able to screen for brain injury in this population, but these studies focused on only a few biomarkers. We hypothesized that using multiplex bead technology we would be able to identify multiple differences in the serum biomarker profile between in children with ITBI and those without brain injury. We compared the concentrations of 44 serum biomarkers in 16 infants with mild ITBI and 20 infants without brain injury. There were significant group differences in the concentrations of nine of the 44 markers. Vascular cellular adhesion molecule (VCAM) (p < 0.00) and IL-6 (IL-6) (p < 0.00) had the most significant group differences; IL-6 was higher after ITBI, whereas VCAM was lower. Using VCAM and IL-6 in classification algorithms, we could discriminate the groups with a sensitivity and specificity of 87% and 90%, respectively. The results suggest significant changes in the serum biomarker profile after mild ITBI. Future research is needed to determine whether these biomarkers can screen for brain injury in infants with nonspecific symptoms.

Transient blockage of the CD11d/CD18 integrin reduces contusion volume and macrophage infiltration after traumatic brain injury in rats

The early inflammatory response to traumatic brain injury (TBI) may result in secondary damage. The purpose of this study was to evaluate the effects of a transient treatment employing a blocking monoclonal antibody (mAb) to the CD11d/CD18 integrin on histopathological outcome and macrophage infiltration following TBI. A parasagittal fluid percussion (FP) brain injury (1.8-2.1 atm) was induced in male Sprague-Dawley rats. Rats were randomized into two trauma groups, treated (N=7) and nontreated (N=8) animals. In the treated group, a mAb to the CD11d subunit of the CD11d/CD18 integrin was administered 30 min, 24 and 48 h after brain injury. Control animals received an isotype-matched irrelevant mAb using the same dose and treatment regimen. At 3 days after TBI, animals were perfusion-fixed for histopathological and immunocytochemical analysis. The anti-CD11d mAb treatment reduced contusion areas as well as overall contusion volume compared to vehicle treated animals. For example, overall contusion volume was reduced from 2.7+/-0.5 mm(3) (mean+/-SEM) to 1.4+/-0.4 with treatment (p<0.05). Immunocytochemical studies identifying CD68 immunoreactive macrophages showed that treatment caused significant attenuation of leukocyte infiltration into the contused cortical areas. These data emphasize the beneficial effects of blocking inflammatory cell recruitment into the injured brain on histopathological outcome following traumatic brain injury.

Normal cellular prion protein is a ligand of selectins: binding requires Le(X) but is inhibited by sLe(X)

The normal PrP(C) (cellular prion protein) contains sLe(X) [sialyl-Le(X) (Lewis X)] and Le(X). sLe(X) is a ligand of selectins. To examine whether PrP(C) is a ligand of selectins, we generated three human PrP(C)-Ig fusion proteins: one with Le(X), one with sLe(X), and the other with neither Le(X) nor sLe(X). Only Le(X)-PrP(C)-Ig binds E-, L- and P-selectins. Binding is Ca(2+)-dependent and occurs with nanomolar affinity. Removal of sialic acid on sLe(X)-PrP(C)-Ig enables the fusion protein to bind all selectins. These findings were confirmed with brain-derived PrP(C). The selectins precipitated PrP(C) in human brain in a Ca(2+)-dependent manner. Treatment of brain homogenates with neuraminidase increased the amounts of PrP(C) precipitated. Therefore the presence of sialic acid prevents the binding of PrP(C) in human brain to selectins. Hence, human brain PrP(C) interacts with selectins in a manner that is distinct from interactions in peripheral tissues. Alternations in these interactions may have pathological consequences.

A gel-based proteomic comparison of human cerebrospinal fluid between inflicted and non-inflicted pediatric traumatic brain injury

Traumatic brain injury (TBI) is the most common cause of traumatic death in infancy, and inflicted TBI (iTBI) is the predominant cause. Like other central nervous system pathologies, TBI changes the composition of cerebrospinal fluid (CSF), which may represent a unique clinical window on brain pathophysiology. Proteomic analysis, including two-dimensional (2-D) difference in gel electrophoresis (DIGE) combined with mass spectrometry (MS), was used to compare the CSF protein profile of two pooled samples from pediatric iTBI (n = 13) and non-inflicted TBI (nTBI; n = 13) patients with severe injury. CSF proteins from iTBI and nTBI were fluorescently labeled in triplicate using different fluorescent Cy dyes and separated by 2-D gel electrophoresis. Approximately 250 protein spots were found in CSF, with 90% between-gel reproducibility of the 2-D gel. Following in-gel digestion, the tryptic peptides were analyzed by MS for protein identification. The acute phase reactant, haptoglobin (HP) isoforms, showed an approximate fourfold increase in nTBI versus iTBI. In contrast, the levels of prostaglandin D(2) synthase (PGDS) and cystatin C (CC) were 12-fold and sevenfold higher in iTBI versus nTBI, respectively. The changes of HP, PGDS, and CC were confirmed by Western blot. These initial results with conventional gel-based proteomics show new protein changes that may ultimately help to understand pathophysiological differences between iTBI and nTBI.

Longitudinal course and clinical significance of TGF-beta1, sL- and sE-Selectins and sICAM-1 levels during severe acute stress in children

OBJECTIVES

To elucidate the potential role of circulating levels of transforming growth factor-beta1 (TGF-beta1), soluble intercellular adhesion molecule-1 (sICAM-1), soluble L- and sE-Selectins (sL- and sE-Selectins) in children with sepsis, traumatic brain injury (TBI) or acute respiratory distress syndrome (ARDS).

DESIGN AND METHODS

Levels of TGF-beta1, sICAM-1, L- and sE-Selectins were determined using solid-phase sandwich enzyme-linked immunosorbent assay in plasma of 10 patients with sepsis, 10 patients with TBI, 10 patients with ARDS, compared to 10 ventilated controls with chronic illness but not in acute stress, on days 1, 3, 5, 7 and 10.

RESULTS

The highest values of sICAM-1 were observed in patients with TBI (p<0.001) and those of sE-Selectin in patients with sepsis (p=0.0001). Patients in the control group did not show an elevation of sE-Selectin and sICAM-1 levels longitudinally. Increased levels of measured molecules (TGF-beta1, p<0.02, sE-Selectin, p<0.02, sL-Selectin, p=0.06, sICAM-1, p<0.03) were demonstrated among survivors in the sepsis and ARDS groups of patients and were positively correlated with length of stay (p<0.04) and mechanical ventilation (p<0.001).

CONCLUSIONS

A sustained increase of adhesion molecules occurs during acute stress in children which may contribute to morbidity in patients with sepsis (sE-Selectin) or traumatic brain injury (sICAM-1). Suppression of the expected response of sE-Selectins, s-ICAM-1 and TGF-beta1 is associated with poor outcome.

Distribution of ICAM-1 immunoreactivity during aging in the human orbitofrontal cortex

Neurological and psychiatric alterations during aging are associated with increased cerebrovascular disturbances and inflammatory markers such as Intercellular Adhesion Molecule-1 (ICAM-1). We investigated whether the distribution of ICAM-1 immunoreactivity (ICAM-1-I) in histological sections from the left orbitofrontal cortex (ORB) was altered during normal aging. Postmortem tissue from the ORB of nine younger (27-54 years old) and 10 older (60-86) human subjects was collected. Cryostat sections were immunostained only with antibodies to ICAM-1 or together with an antibody to glial fibrillary acidic protein (GFAP). The total area fraction of ICAM-1-I, and the fraction of vascular and extravascular ICAM-1-I were quantified in the gray matter. Furthermore, we examined the association of extravascular ICAM-1-I to GFAP immunoreactive (GFAP-IR) astrocytes. In all subjects, brain blood vessels were similarly ICAM-1 immunoreactive, and in some subjects there was a variable number of extravascular patches of ICAM-1-I. The area fraction of ICAM-1-I was 120% higher (p<.0001) in the old subjects than in the young subjects. This increase localized mostly to the extravascular ICAM-1-I in register with GFAP-IR astrocytes. A much smaller, also age-dependent increase occurred in vascular ICAM-1-I. Our results indicate a dramatic increase in extravascular ICAM-1-I associated to GFAP-IR astrocytes in the ORB in normal aging. This increase may contribute to an enhanced risk for brain inflammatory processes during aging, although a role of extravascular ICAM-1 as a barrier to further inflammation cannot be ruled out.

Pediatric traumatic brain injury: past, present and future

Traumatic brain injury (TBI) is the leading cause of death and disability in children. Evidence-based guidelines for the management of this population are available; however, the data highlight significant deficiencies with few treatment standards or guidelines. Considering the limited availability of resources, it is necessary to define realistic goals. Attention should be given to injury prevention, developing standardized pediatric admission and outcome evaluations, increasing the utility and spectrum of physiological and biochemical testing, and defining the evolving role of imaging in TBI.

Traumatic injury to the immature brain: inflammation, oxidative injury, and iron-mediated damage as potential therapeutic targets

Traumatic brain injury (TBI) is the leading cause of morbidity and mortality among children and both clinical and experimental data reveal that the immature brain is unique in its response and vulnerability to TBI compared to the adult brain. Current therapies for pediatric TBI focus on physiologic derangements and are based primarily on adult data. However, it is now evident that secondary biochemical perturbations play an important role in the pathobiology of pediatric TBI and may provide specific therapeutic targets for the treatment of the head-injured child. In this review, we discuss three specific components of the secondary pathogenesis of pediatric TBI-- inflammation, oxidative injury, and iron-induced damage-- and potential therapeutic strategies associated with each. The inflammatory response in the immature brain is more robust than in the adult and characterized by greater disruption of the blood-brain barrier and elaboration of cytokines. The immature brain also has a muted response to oxidative stress compared to the adult due to inadequate expression of certain antioxidant molecules. In addition, the developing brain is less able to detoxify free iron after TBI-induced hemorrhage and cell death. These processes thus provide potential therapeutic targets that may be tailored to pediatric TBI, including anti-inflammatory agents such as minocycline, antioxidants such as glutathione peroxidase, and the iron chelator deferoxamine.

Assessment of the Macrophage Marker Quinolinic Acid in Cerebrospinal Fluid after Pediatric Traumatic Brain Injury: Insight into the Timing and Severity of Injury in Child Abuse

This study measured quinolinic acid (QUIN), a macrophage-microglia derived neurotoxin, in the cerebrospinal fluid (CSF) of children after non-inflicted and inflicted traumatic brain injury (nTBI, iTBI), and correlated QUIN concentrations with age, mechanism of injury (nTBi vs. iTBI), Glasgow Coma Scale (GCS) score and 6-month Glasgow Outcome Score. One hundred fifty-two CSF samples were collected from 51 children with severe TBI (GCS < or = 8). CSF was collected at the time an intraventricular catheter was placed and daily thereafter. QUIN concentration was measured by gas chromatography-mass spectroscopy. Patients ranged in age from 2 months to 16 years. Eleven children (22%) had iTBI. Initial and peak CSF QUIN concentrations were higher in patients with iTBI versus nTBI after adjusting for time after injury and GCS. Despite the lack of a history of trauma in 82% of children with iTBI, 100% had a peak QUIN concentration of >100 nM. There was a significant increase in the CSF concentrations of QUIN following severe nTBI and iTBI in children. Higher initial and peak QUIN concentrations after iTBI may be due to severity of injury, young age, and/or delay in seeking medical care, which allows for increased secondary injury.

Biochemical markers of brain injury: could they be used as diagnostic adjuncts in cases of inflicted traumatic brain injury?

Child abuse is the leading cause of serious traumatic brain injury (TBI) in infants and young children (Billmire & Myers, 1985; Bruce & Zimmerman, 1989). The incidence of serious or fatal inflicted traumatic brain injury (iTBI) in children < 1 year of age is approximately 1 in 3,300 ( Keenan et al., 2003); since many cases of iTBI are of mild or moderate severity, the incidence is probably significantly higher. Even at an incidence of 1 in 3,300, iTBI is as common as the incidence of cystic fibrosis (CF), the most common genetic recessive disease in the Caucasian population. Proper diagnosis of iTBI is difficult even for experienced and astute physicians because its presentation can be subtle and important historical data are often lacking. As a result, misdiagnosis is common and can have catastrophic medical consequences for patients and significant financial consequences for society ( Ewing-Cobbs et al., 1998; Jenny, Hymel, Pitzen, Reinert, & Hay, 1999). Unlike CF for which there are several well established screening tests, there are currently no diagnostic adjuncts to help physicians screen for possible iTBI.

Sialylated complex-type N-glycans enhance the signaling activity of soluble intercellular adhesion molecule-1 in mouse astrocytes

Intercellular adhesion molecule-1 (ICAM-1) occurs as both a membrane and a soluble, secreted glycoprotein (sICAM-1). ICAM-1 on endothelial cells mediates leukocyte adhesion by binding to leukocyte function associated antigen-1 (LFA-1) and macrophage antigen-1 (Mac-1). Recombinant mouse sICAM-1 induces the production of macrophage inflammatory protein-2 (MIP-2) in mouse astrocytes by a novel LFA-1- and Mac-1-independent mechanism. Here we showed that N-glycan structures of sICAM-1 influence its ability to induce MIP-2 production. sICAM-1 expressed in Chinese hamster ovary (CHO) cells was a more potent inducer of MIP-2 production than sICAM-1 expressed in HEK 293 cells, suggesting that posttranslational modification of sICAM-1 could influence its signaling activity. To explore the roles of glycosylation in sICAM-1 activity, we expressed sICAM-1 in mutant CHO cell lines differing in glycosylation, including Lec2, Lec8, and Lec1 as well as in CHO cells cultured in the presence of the alpha-mannosidase-I inhibitor kifunensine. Signaling activity of sICAM-1 lacking sialic acid was reduced 3-fold compared with sICAM-1 from CHO cells. The activity of sICAM-1 lacking both sialic acid and galactose was reduced 12-fold, whereas the activity of sICAM-1 carrying only high mannose-type N-glycans was reduced 12-26-fold. sICAM-1 glycoforms carrying truncated glycans retained full ability to bind to LFA-1 on leukocytes. Thus, sialylated and galactosylated complex-type N-glycans strongly enhanced the ability of sICAM-1 to induce MIP-2 production in astrocytes but did not alter its binding to LFA-1 on leukocytes. Glycosylation could therefore serve as a means to regulate specifically the signaling function of sICAM-1 in vivo.

Increased diffusion of soluble adhesion molecules in meningitis, severe sepsis and systemic inflammatory response without neurological infection is associated with intrathecal shedding in cases of meningitis

OBJECTIVE

Sepsis and systemic inflammatory response syndrome (SIRS) result in the release in plasma of inflammatory cytokines and soluble forms of adhesion molecules in relation to endothelial activation. This study was designed to compare cerebrospinal fluid (CSF) concentrations of adhesion molecules in meningitis and SIRS without neurological infection and to evaluate in meningitis whether they originate from passive diffusion through damaged blood-CSF barrier or from local production.

DESIGN

Prospective observational study.

SETTING

University hospital medical intensive care unit.

PATIENTS

Nineteen patients with meningitis and 41 patients with sepsis or SIRS without cerebrospinal infection consecutively admitted to the critical care unit over an 18-month period.

INTERVENTIONS

Soluble forms of adhesion molecules (ICAM-1, VCAM-1, E-selectin) and cytokines (interleukin (IL)-1beta and TNF-alpha) were measured in paired CSF and blood samples.

RESULTS

Serum concentrations of soluble adhesion molecules and cytokines were increased in the two groups, without significant differences. The CSF concentrations were elevated in both cases, whereas patients with meningitis demonstrated significantly higher CSF concentrations of soluble ICAM-1, VCAM-1, E-selectin, and TNF-alpha ( p<0.001), with higher corresponding CSF/serum ratios. Correlations between CSF and serum concentrations were found only in meningitis. These correlations were strong for soluble ICAM-1 (r(2)=0.7, p<0.001) and E-selectin (r(2)=0.9, p<0.001), but weaker for VCAM-1. VCAM-1 CSF/serum ratios were increased, in comparison with ICAM-1 and E-selectin CSF/serum ratios, despite similar molecular weights. Serum and CSF levels of cytokines and adhesion molecules were not predictive of death for the whole population, except concentrations of ICAM-1 significantly increased in non-surviving patients ( p<0.05).

CONCLUSIONS

The CSF soluble adhesion molecules are increased in sepsis, SIRS and meningitis. In meningitis, the correlation between CSF and serum concentrations of adhesion molecules and the presence of a discrepancy of CSF/serum ratios for molecules of the same molecular weight may suggest intrathecal shedding in addition to diffusion through blood-CSF barrier.

F2-isoprostane and neuron-specific enolase in cerebrospinal fluid after severe traumatic brain injury in infants and children

It has been hypothesized that oxidative stress plays an important role in mediating secondary damage after traumatic brain injury (TBI). To study the relationship between lipid peroxidation, clinical variables, and neuronal damage in pediatric TBI, we measured levels of F2-isoprostane, a marker of lipid peroxidation, and neuron-specific enolase (NSE), a marker of neuronal damage, in serial cerebrospinal fluid (CSF) samples from 23 infants and children with severe TBI (Glasgow Coma Scale score <8). These were compared to CSF samples from 10 uninjured pediatric controls. On d1 after injury, F2-isoprostane was increased 6-fold vs. control (36.59+/-8.96 pg/ml vs. 5.64+/-8.08 pg/ml, p=0.0035) and NSE was increased 10-fold (100.62+/-17.34 ng/ml vs. 8.63+/-2.76 ng/ml, p=0.0002). Multivariate analysis of F2-isoprostane levels and selected clinical variables showed a trend toward an inverse association with time after injury (p=0.0708). Multivariate analysis of NSE levels and selected variables showed a positive association between d1 NSE and F2-isoprostane (p=0.0426). CSF F2-isoprostane increases early after TBI in infants and children and is correlated with NSE, supporting a role for oxidative stress in the evolution of secondary damage early after severe TBI in infants and children.

Traumatic brain injury in infants and children: mechanisms of secondary damage and treatment in the intensive care unit

Unfortunately no specific pharmacologic therapies are available for the treatment of TBI in patients. Current investigation of contemporary therapies for the treatment of TBI consists of recycling of previously tested therapies in the era of contemporary neurointensive care. These therapies include hypothermia, decompressive craniectomy, osmotherapy, and controlled hyperventilation. It is hoped that more detailed knowledge regarding the dominant pathophysiologic mechanisms associated with TBI-excitotoxicity, CBF dysregulation, oxidative stress, and programmed cell death-will catapult an efficacious intervention from the laboratory bench to the bedside. This intervention may be a potent agent targeting a single dominant pathway, a broad-spectrum intervention such as hypothermia, or, more likely, a combination of therapies. Meanwhile, practitioners must offer meticulous supportive neurointensive care using clinically proven therapies aimed at minimizing cerebral swelling for the management of pediatric patients who are victims of TBI.

Administration of either anti-intercellular adhesion molecule-1 or a nonspecific control antibody improves recovery after traumatic brain injury in the rat

Intercellular adhesion molecule-1 (ICAM-1) is an endothelial protein that facilitates invasion of leukocytes into the CNS in response to injury or inflammation. ICAM-1 expression correlates with the severity of clinical head injuries, but its importance in secondary injury events is not fully understood. Therefore, we evaluated ICAM-1 expression and the effect of anti-ICAM-1 treatment on motor recovery and neutrophil invasion after traumatic brain injury induced via the lateral fluid-percussion method in the rat. ICAM-1 was expressed in large and small blood vessels within the injured cortex at 10 and 24 h after injury. Repeated administration of anti-ICAM-1 antibody (clone 1A29) at 1, 10, and again at 24 h after injury significantly improved performance in two of three motor tests, compared to saline controls. Equal doses of nonspecific control antibody (IgG) also significantly improved motor test scores, compared to saline controls. Cortical myeloperoxidase activity, an indicator of neutrophil invasion, was significantly reduced 26 h after injury in animals treated with anti-ICAM-1. Animals treated with IgG showed a trend toward reduction that did not reach significance. These data suggest that ICAM-1 may be involved in neutrophil invasion and neurological dysfunction after TBI, but also implicate a role for a nonspecific antibody effect in improved functional outcome.

Critical mechanisms of secondary damage after inflicted head injury in infants and children

A number of critical mechanisms are involved in the pathophysiology of inflicted head injury. Excitotoxicity, oxidative stress, inflammation, programmed cell death, and mediators of blood flow and metabolism all contribute to secondary injury after abusive head trauma. These mechanisms are reviewed and the implications for clinical practice discussed.

Levels of soluble adhesion molecules are elevated in the cerebrospinal fluid of children with moyamoya syndrome

OBJECTIVE

The pathogenesis of moyamoya syndrome is unknown; however, previous studies suggested an inflammatory component. Because adhesion molecules mediate inflammation during cerebral ischemia, we measured the levels of soluble isoforms of the endothelial adhesion molecules vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin in serum and cerebrospinal fluid (CSF) samples from children with moyamoya syndrome.

METHODS

Serum and CSF samples were obtained from children with moyamoya syndrome (n = 20) and patients with congenital spinal deformities (n = 20). Soluble vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin levels were measured in enzyme-linked immunoassays. The correlation between the levels of soluble adhesion molecules and the Suzuki angiographic classification was analyzed. CSF/serum albumin index values were also measured, to determine the integrity of the blood-brain barrier.

RESULTS

Compared with the control group, children with moyamoya syndrome exhibited significantly elevated CSF levels of soluble vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin. The albumin index for the moyamoya group was 9, which was significantly higher than that for the control group. However, there were no differences in the serum levels of the three soluble adhesion molecules and no correlations between age, Suzuki classification, and serum and CSF levels of adhesion molecules.

CONCLUSION

Our study demonstrates increased CSF levels of soluble endothelial adhesion molecules, suggesting that children with moyamoya syndrome have ongoing central nervous system inflammation, with slight impairment of the blood-brain barrier. These soluble adhesion molecules may be clinically useful as indicators of this inflammatory process and may provide some insight into this enigmatic disease process.

Neuron-specific enolase and S100B in cerebrospinal fluid after severe traumatic brain injury in infants and children

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of death and disability in children. Considerable insight into the mechanisms involved in secondary injury after TBI has resulted from analysis of ventricular cerebrospinal fluid (CSF) obtained in children with severe noninflicted and inflicted TBI (nTBI and iTBI, respectively). Neuron-specific enolase (NSE) is a glycolytic enzyme that is localized primarily to the neuronal cytoplasm. S100B is a calcium-binding protein localized to astroglial cells. In adults, CSF and serum concentrations of NSE and S100B have served as markers of neuronal damage after TBI. Neither NSE nor S100B has previously been studied in CSF after TBI in infants or children.

OBJECTIVE

To compare the time course and magnitude of neuronal and astroglial death after nTBI and iTBI by measuring CSF concentrations of NSE and S100B using a rapid enzyme-linked immunosorbent assay.

METHODS

Severe nTBI and iTBI were defined by strict clinical criteria. Serial ventricular CSF samples (n = 35) were obtained from children 1.5 to 9 years with severe nTBI (n = 5) and children 0.2 to 1.5 years (n = 5) with severe iTBI. Lumbar CSF samples from 5 children 0.1 to 2.3 years evaluated for meningitis were used as a comparison group. CSF NSE and S100B concentrations were quantified by an enzyme-linked immunosorbent assay (SynX Pharma Inc, Ontario, Canada).

RESULTS

There was no difference in age between patients with iTBI (median [range]: 0.2 years [0.2-1.8]), nTBI (2.0 years [1.5-9]), and the comparison group (0.2 years [0.2-1.8]). The initial Glasgow Coma Scale score was higher in the iTBI group (9 [4-14]) versus the nTBI group (3 [3-7]). NSE was increased in TBI versus the comparison group in 34 of 35 samples. Mean NSE was markedly increased (mean +/- SEM, 117.1 +/- 12.0 ng/mL vs 3.5 +/- 1.4 ng/mL). After nTBI, a transient peak in NSE was seen at a median of 11 hours after injury (range: 5-20 hours). After iTBI, an increase in admission NSE was followed by a sustained and delayed peak at a median of 63 hours after injury (range: 7-94). The magnitude of peak NSE was similar in nTBI and iTBI. S100B was increased versus the comparison group in 35 of 35 samples. Mean S100B was markedly increased in TBI versus the comparison group (1.67 +/- 0.2 ng/mL vs 0.02 +/- 0.0 ng/mL). S100B showed a single peak at 27 hours (range: 5-63 hours) after both nTBI and iTBI. The mean S100B concentration, peak S100B concentration, and the time to peak were not associated with mechanism of injury.

CONCLUSIONS

Markers of neuronal and astroglial death are markedly increased in CSF after severe nTBI and iTBI. ITBI produces a unique time course of NSE, characterized by both an early and late peak, presumably representing 2 waves of neuronal death, the second of which may represent apoptosis. Delayed neuronal death may represent an important therapeutic target in iTBI. NSE and S100B may also be useful as markers to identify occult iTBI, help differentiate nTBI and iTBI, and assist in determining the time of injury in cases of iTBI.

Cerebrospinal fluid procalcitonin and severe traumatic brain injury in children

OBJECTIVE

To determine the relationship between cerebrospinal fluid procalcitonin concentration and severe traumatic brain injury in children.

DESIGN

Prospective, observational clinical study.

SETTING

A multidisciplinary, tertiary-care pediatric intensive care unit.

PATIENTS

Twenty-eight patients who required external ventricular drainage for management of severe traumatic brain injury (Glasgow Coma Scale score of <8) and 22 control patients for whom lumbar cerebrospinal fluid evaluation excluded possible meningitis.

INTERVENTIONS

Standard intracranial pressure-directed neurointensive care, including intraventricular catheter placement and continuous cerebrospinal fluid drainage, was used to manage patients with severe traumatic brain injury.

MEASUREMENTS AND MAIN RESULTS

Demographic data including age, mechanism of injury, time of injury, initial Glasgow Coma Scale score, and outcome were collected. Cerebrospinal fluid procalcitonin concentration was determined by immunoluminometric assay. Initial cerebrospinal fluid procalcitonin concentration (median [range]) in patients with severe traumatic brain injury was increased greater than three-fold vs. controls (0.41 ng/mL [0.15-2.14] vs. 0.12 ng/mL [0.00-0.24], p <.001). Initial cerebrospinal fluid procalcitonin concentration among patients with abusive head trauma (0.31 ng/mL [0.29-0.50]) also was increased vs. controls (p <.05), although this increase was less robust than patients with accidental trauma (0.41 ng/mL [0.15-2.14], p <.001 vs. controls). Additional examination of key demographic and outcome variables with a generalized linear regression model was performed for patients with severe traumatic brain injury. Univariate analysis revealed that both time after injury (p <.01) and abusive head trauma as a mechanism of injury (p <.001) were associated with attenuation of the increased cerebrospinal fluid procalcitonin response after traumatic brain injury.

CONCLUSION

Cerebrospinal fluid procalcitonin concentration is increased in children after traumatic brain injury. The attenuated increase in cerebrospinal fluid procalcitonin among victims of abusive head trauma warrants further study because it may reflect impairment of endogenous neuroprotective mechanisms or delay in seeking medical attention. The significance of these observations remains to be determined as future studies elucidate the physiologic and mechanistic properties of procalcitonin.

Expression of P-selectin and intercellular adhesion molecule-1 in human brain after focal infarction or cardiac arrest

Data from experimental studies indicate that acute inflammation contributes to ischaemic brain damage. Tethering of neutrophils to brain endothelium is mediated by selectins, and subsequent adhesion and migration by endothelial intercellular adhesion molecule-1 (ICAM-1) and neutrophil CD18. In experimental studies of ischaemia-reperfusion injury, brain damage has been ameliorated by administration of antibodies to these adhesion molecules. We studied the expression of P-selectin and ICAM-1 in sections of brain from patients who had experienced cardiac arrest or focal brain infarction, and who died 3.5 h to 9 days later. Endothelial immunopositivity for both adhesion molecules was maximal at about 2-3 days then declined. Between 1 day and 3 days, P-selectin was also detected on platelets in blood vessels within infarcted tissue. Within infarcts, but not sections of brain from cardiac arrest patients, P-selectin and ICAM-1 were again detectable at 1 week, when hyperplastic endothelial cells were labelled in capillaries in and immediately adjacent to the infarcted tissue. The finding that P-selectin and ICAM-1 are upregulated within focally infarcted brain tissue supports the concept that blocking neutrophil adhesion may be of benefit in treating atherothrombotic strokes in man.

Increased adenosine in cerebrospinal fluid after severe traumatic brain injury in infants and children: association with severity of injury and excitotoxicity

OBJECTIVES

To measure adenosine concentration in the cerebrospinal fluid of infants and children after severe traumatic brain injury and to evaluate the contribution of patient age, Glasgow Coma Scale score, mechanism of injury, Glasgow Outcome Score, and time after injury to cerebrospinal fluid adenosine concentrations. To evaluate the relationship between cerebrospinal fluid adenosine and glutamate concentrations in this population.

DESIGN

Prospective survey.

SETTING

Pediatric intensive care unit in a university-based children's hospital.

PATIENTS

Twenty-seven critically ill infants and children who had severe traumatic brain injury (Glasgow Coma Scale < 8), who required placement of an intraventricular catheter and drainage of cerebrospinal fluid as part of their neurointensive care.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients ranged in age from 2 months to 14 yrs. Cerebrospinal fluid samples (n = 304) were collected from 27 patients during the first 7 days after traumatic brain injury. Control cerebrospinal fluid samples were obtained from lumbar puncture on 21 infants and children without traumatic brain injury or meningitis. Adenosine concentration was measured by using high-pressure liquid chromatography. Adenosine concentration was increased markedly in cerebrospinal fluid of children after traumatic brain injury vs. controls (p < .001). The increase in cerebrospinal fluid adenosine was independently associated with Glasgow Coma Scale < or = 4 vs. > 4 and time after injury (both p < .005). Cerebrospinal fluid adenosine concentration was not independently associated with either age (< or = 4 vs. > 4 yrs), mechanism of injury (abuse vs. other), or Glasgow Outcome Score (good/moderately disabled vs. severely disabled, vegetative, or dead). Of the 27 patients studied, 18 had cerebrospinal fluid glutamate concentration previously quantified by high-pressure liquid chromatography. There was a strong association between increases in cerebrospinal fluid adenosine and glutamate concentrations (p < .005) after injury.

CONCLUSIONS

Cerebrospinal fluid adenosine concentration is increased in a time- and severity-dependent manner in infants and children after severe head injury. The association between cerebrospinal fluid adenosine and glutamate concentrations may reflect an endogenous attempt at neuroprotection against excitotoxicity after severe traumatic brain injury.

The kinetics, function, and regulation of P-selectin expressed by human brain microvessel endothelial cells in primary culture

P-selectin is an endothelial cell adhesion glycoprotein expressed on the cell surface early in inflammation where it binds to blood leukocytes. This study examines the expression, function, and regulation of P-selectin in primary cultures of human brain microvessel endothelial cells (HBMEC). Surface expression of P-selectin was minimal in unstimulated HBMEC; however, it was significantly augmented upon stimulation with histamine (10(-7)-10(-3) M) and thrombin (0.01-1 U/ml). Expression increased rapidly at 10 min and remained elevated at 60 min. Immunogold electron microscopy showed that histamine (10(-7) M) increased surface expression preferentially on the apical surface of subconfluent monolayers. A cell binding assay showed that the adhesion of polymorphonuclear leukocytes (PMNs) to confluent monolayers was augmented after histamine treatment. Histamine-induced surface expression of P-selectin was blocked by the histamine H2 receptor antagonist cimetidine. The H1 receptor antagonist mepyramine had no effect. Expression was reduced by the extracellular calcium chelator EDTA and blocked by the cyclic AMP phosphodiesterase inhibitor rolipram. Thus histamine and thrombin both increase P-selectin expression in HBMEC. Histamine mediates expression through the H2, but not the H1, receptor and calcium, whereas expression is reduced by cyclic AMP. The histamine-induced expression increases PMN binding to the HBMEC. These data suggest that P-selectin plays a role in the recruitment of acute inflammatory cells to the CNS.

A review and rationale for the use of genetically engineered animals in the study of traumatic brain injury

The mechanisms underlying secondary cell death after traumatic brain injury (TBI) are poorly understood. Animal models of TBI recapitulate many clinical and pathologic aspects of human head injury, and the development of genetically engineered animals has offered the opportunity to investigate the specific molecular and cellular mechanisms associated with cell dysfunction and death after TBI, allowing for the evaluation of specific cause-effect relations and mechanistic hypotheses. This article represents a compendium of the current literature using genetically engineered mice in studies designed to better understand the posttraumatic inflammatory response, the mechanisms underlying DNA damage, repair, and cell death, and the link between TBI and neurodegenerative diseases.

Effect of neutropenia and granulocyte colony stimulating factor-induced neutrophilia on blood-brain barrier permeability and brain edema after traumatic brain injury in rats

OBJECTIVE

Granulocyte colony stimulating factor (GCSF) has been used to increase systemic absolute neutrophil count (ANC) in patients with severe traumatic brain injury to reduce nosocomial infection risk. However, the effect of increasing systemic ANC on the pathogenesis of experimental traumatic brain injury has not been studied. Thus, we evaluated the effect of systemic ANC on blood-brain barrier (BBB) damage and brain edema after traumatic brain injury in rats.

DESIGN

Experimental study.

SETTING

Research laboratory at the University of Pittsburgh, PA.

SUBJECTS

Forty-three adult male Sprague-Dawley rats.

INTERVENTIONS

Protocol I: rats were randomized to receive either vinblastine sulfate to reduce ANC, GCSF to increase ANC, or saline before controlled cortical impact (CCI) of moderate overall severity. Evans blue was used to assess BBB damage at 4-24 hrs after CCI. Protocol II: rats received GCSF or saline before CCI. Brain edema was estimated at 24 hrs using wet - dry) / wet weight method. Protocol III: rats received GCSF or saline before CCI. Brain neutrophil accumulation was estimated at 24 hrs using a myeloperoxidase assay.

MEASUREMENTS AND MAIN RESULTS

Physiologic variables were controlled before CCI was maintained at normal in all animals before traumatic brain injury. No rats were anemic, hypoglycemic, or hypotensive before CCI. Protocol I: compared with control, systemic ANC decreased in vinblastine-treated rats and increased in GCSF-treated rats. BBB damage correlated with systemic ANC. Protocol II: mean systemic ANC before traumatic brain injury increased 15-fold in rats given GCSF vs. control; however no difference in brain edema was observed at 24 hrs after injury between groups. Protocol III: median systemic ANC at the time of CCI was increased ten-fold in rats given GCSF vs. control. No difference in brain myeloperoxidase activity 24 hrs after CCI was observed in rats treated with GCSF vs. control.

CONCLUSIONS

Systemic ANC influences BBB damage after traumatic brain injury produced by CCI. Because BBB damage and brain edema are discordant, mechanisms other than BBB damage likely predominate in the pathogenesis of brain edema after contusion. The implications of increased BBB permeability with the administration of GCSF in our model remains to be determined. Increasing systemic ANC before CCI with GCSF administration does not increase posttraumatic brain neutrophil accumulation or brain edema after CCI in rats. The finding that neutrophil infiltration is not enhanced by systemic neutrophilia suggests that the ability of GCSF-stimulated neutrophils to migrate into injured tissue may be impaired. Further studies are needed to evaluate the effects of GCSF administration on secondary injury and functional outcome in experimental models of traumatic brain injury.

Increases in bcl-2 protein in cerebrospinal fluid and evidence for programmed cell death in infants and children after severe traumatic brain injury

OBJECTIVES

To determine whether bcl-2, a protein that inhibits apoptosis, would be increased in cerebrospinal fluid (CSF) in infants and children after traumatic brain injury (TBI) and to examine the association of bcl-2 concentration with clinical variables.

STUDY DESIGN

Bcl-2 was measured in CSF from 23 children (aged 2 months-16 years) with severe TBI and from 19 children without TBI or meningitis (control subjects) by enzyme-linked immunosorbent assay. CSF oligonucleosome concentration was also determined as a marker of DNA degradation. Brain samples from 2 patients undergoing emergent decompressive craniectomies were analyzed for bcl-2 with Western blot and for DNA fragmentation with TUNEL (terminal deoxynucleotidyl-transferase mediated biotin-dUTP nick-end labeling).

RESULTS

CSF bcl-2 concentrations were increased in patients with TBI versus control subjects (P =.01). Bcl-2 was increased in patients with TBI who survived versus those who died (P =.02). CSF oligonucleosome concentration tended to be increased after TBI (P =.07) and was not associated with bcl-2. Brain tissue samples showed an increase in bcl-2 in patients with TBI versus adult brain bank control samples and evidence of DNA fragmentation within cells with apoptotic morphology.

CONCLUSIONS

Bcl-2 may participate in the regulation of cell death after TBI in infants and children. The increase in bcl-2 seen in patients who survived is consistent with a protective role for this anti-apoptotic protein after TBI.