α-Synuclein levels are elevated in cerebrospinal fluid following traumatic brain injury in infants and children: the effect of therapeutic hypothermia

Pathophysiology and Neuroimmune Interactions Underlying Parkinson's Disease and Traumatic Brain Injury

Parkinson's disease (PD) is a progressive neurodegenerative disorder clinically defined by motor instability, bradykinesia, and resting tremors. The clinical symptomatology is seen alongside pathologic changes, most notably the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the accumulation of α-synuclein and neuromelanin aggregates throughout numerous neural circuits. Traumatic brain injury (TBI) has been implicated as a risk factor for developing various neurodegenerative diseases, with the most compelling argument for the development of PD. Dopaminergic abnormalities, the accumulation of α-synuclein, and disruptions in neural homeostatic mechanisms, including but not limited to the release of pro-inflammatory mediators and the production of reactive oxygen species (ROS), are all present following TBI and are closely related to the pathologic changes seen in PD. Neuronal iron accumulation is discernable in degenerative and injured brain states, as is aquaporin-4 (APQ4). APQ4 is an essential mediator of synaptic plasticity in PD and regulates edematous states in the brain after TBI. Whether the cellular and parenchymal changes seen post-TBI directly cause neurodegenerative diseases such as PD is a point of considerable interest and debate; this review explores the vast array of neuroimmunological interactions and subsequent analogous changes that occur in TBI and PD. There is significant interest in exploring the validity of the relationship between TBI and PD, which is a focus of this review.

Increased Risk of Aging-Related Neurodegenerative Disease after Traumatic Brain Injury

Traumatic brain injury (TBI) survivors frequently suffer from chronically progressive complications, including significantly increased risk of developing aging-related neurodegenerative disease. As advances in neurocritical care increase the number of TBI survivors, the impact and awareness of this problem are growing. The mechanisms by which TBI increases the risk of developing aging-related neurodegenerative disease, however, are not completely understood. As a result, there are no protective treatments for patients. Here, we review the current literature surrounding the epidemiology and potential mechanistic relationships between brain injury and aging-related neurodegenerative disease. In addition to increasing the risk for developing all forms of dementia, the most prominent aging-related neurodegenerative conditions that are accelerated by TBI are amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Parkinson's disease (PD), and Alzheimer's disease (AD), with ALS and FTD being the least well-established. Mechanistic links between TBI and all forms of dementia that are reviewed include oxidative stress, dysregulated proteostasis, and neuroinflammation. Disease-specific mechanistic links with TBI that are reviewed include TAR DNA binding protein 43 and motor cortex lesions in ALS and FTD; alpha-synuclein, dopaminergic cell death, and synergistic toxin exposure in PD; and brain insulin resistance, amyloid beta pathology, and tau pathology in AD. While compelling mechanistic links have been identified, significantly expanded investigation in the field is needed to develop therapies to protect TBI survivors from the increased risk of aging-related neurodegenerative disease.

Non-coding RNAs and Exosomal Non-coding RNAs in Traumatic Brain Injury: the Small Player with Big Actions

Nowadays, there is an increasing concern regarding traumatic brain injury (TBI) worldwide since substantial morbidity is observed after it, and the long-term consequences that are not yet fully recognized. A number of cellular pathways related to the secondary injury in brain have been identified, including free radical production (owing to mitochondrial dysfunction), excitotoxicity (regulated by excitatory neurotransmitters), apoptosis, and neuroinflammatory responses (as a result of activation of the immune system and central nervous system). In this context, non-coding RNAs (ncRNAs) maintain a fundamental contribution to post-transcriptional regulation. It has been shown that mammalian brains express high levels of ncRNAs that are involved in several brain physiological processes. Furthermore, altered levels of ncRNA expression have been found in those with traumatic as well non-traumatic brain injuries. The current review highlights the primary molecular mechanisms participated in TBI that describes the latest and novel results about changes and role of ncRNAs in TBI in both clinical and experimental research.

Co-administration of Nanowired DL-3-n-Butylphthalide (DL-NBP) Together with Mesenchymal Stem Cells, Monoclonal Antibodies to Alpha Synuclein and TDP-43 (TAR DNA-Binding Protein 43) Enhance Superior Neuroprotection in Parkinson's Disease Following Concussive Head Injury

dl-3-n-butylphthalide (dl-NBP) is one of the potent antioxidant compounds that induces profound neuroprotection in stroke and traumatic brain injury. Our previous studies show that dl-NBP reduces brain pathology in Parkinson's disease (PD) following its nanowired delivery together with mesenchymal stem cells (MSCs) exacerbated by concussive head injury (CHI). CHI alone elevates alpha synuclein (ASNC) in brain or cerebrospinal fluid (CSF) associated with elevated TAR DNA-binding protein 43 (TDP-43). TDP-43 protein is also responsible for the pathologies of PD. Thus, it is likely that exacerbation of brain pathology in PD following brain injury may be thwarted using nanowired delivery of monoclonal antibodies (mAb) to ASNC and/or TDP-43. In this review, the co-administration of dl-NBP with MSCs and mAb to ASNC and/or TDP-43 using nanowired delivery in PD and CHI-induced brain pathology is discussed based on our own investigations. Our observations show that co-administration of TiO2 nanowired dl-NBP with MSCs and mAb to ASNC with TDP-43 induced superior neuroprotection in CHI induced exacerbation of brain pathology in PD, not reported earlier.

Role of TREM2 in the Development of Neurodegenerative Diseases After Traumatic Brain Injury

Traumatic brain injury (TBI) has been found as the primary cause of morbidity and disability worldwide, which has posed a significant social and economic burden. The first stage of TBI produces brain edema, axonal damage, and hypoxia, thus having an effect on the blood-brain barrier function, promoting inflammatory responses, and increasing oxidative stress. Patients with TBI are more likely to develop post-traumatic epilepsy, behavioral issues, as well as mental illnesses. The long-term effects arising from TBI have aroused rising attention over the past few years. Microglia in the brain can express the triggering receptor expressed on myeloid cells 2 (TREM2), which is a single transmembrane receptor pertaining to the immunoglobulin superfamily. The receptor has been correlated with a number of neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and other relevant diseases. In this review, it is demonstrated that TREM2 is promising to serve as a neuroprotective factor for neurodegenerative disorders following TBI by modulating the function of microglial cells. Accordingly, it has potential avenues for TREM2-related therapies to improve long-term recovery after TBI.

Proteinopathies and Neurotrauma: Update on Degenerative Cascades

Neurotrauma, especially repetitive neurotrauma, is associated with the development of progressive neurodegeneration leading to chronic traumatic encephalopathy (CTE). Exposure to neurotrauma regularly occurs during sports and military service, often not requiring medical care. However, exposure to severe and/or repeated sub-clinical neurotrauma has been shown cause physical and psychological disability, leading to reduce life expectancy. Misfolding of proteins, or proteinopathy, is a pathological hallmark of CTE, in which chronic injury leads to local and diffuse protein aggregates. These aggregates are an overlapping feature of many neurodegenerative diseases such as CTE, Alzheimer's Disease, Parkinsons disease. Neurotrauma is also a significant risk factor for the development of these diseases, however the mechanism's underlying this association are not well understood. While phosphorylated tau aggregates are the primary feature of CTE, amyloid-beta, Transactive response DNA-binding protein 43 (TDP-43), and alpha-synuclein (αSyn) are also well documented. Aberrant misfolding of these proteins has been shown to disrupt brain homeostasis leading to neurodegeneration in a disease dependent manor. In CTE, the interaction between proteinopathies and their associated neurodegeneration is a current area of study. Here we provide an update on current literature surrounding the prevalence, characteristics, and pathogenesis of proteinopathies in CTE.

Mesenchymal Stem Cell-Induced Anti-Neuroinflammation Against Traumatic Brain Injury

Traumatic brain injury (TBI) is a pervasive and damaging form of acquired brain injury (ABI). Acute, subacute, and chronic cell death processes, as a result of TBI, contribute to the disease progression and exacerbate outcomes. Extended neuroinflammation can worsen secondary degradation of brain function and structure. Mesenchymal stem cell transplantation has surfaced as a viable approach as a TBI therapeutic due to its immunomodulatory and regenerative features. This article examines the role of inflammation and cell death in ABI as well as the effectiveness of bone marrow-derived mesenchymal stem/stromal cell (BM-MSC) transplants as a treatment for TBI. Furthermore, we analyze new studies featuring transplanted BM-MSCs as a neurorestorative and anti-inflammatory therapy for TBI patients. Although clinical trials support BM-MSC transplants as a viable TBI treatment due to their promising regenerative characteristics, further investigation is imperative to uncover innovative brain repair pathways associated with cell-based therapy as stand-alone or as combination treatments.

Differential Regional Responses in Soluble Monomeric Alpha Synuclein Abundance Following Traumatic Brain Injury

Alpha synuclein (α-synuclein) is a neuronal protein found predominately in presynaptic terminals. While the pathological effect of α-synuclein aggregates has been a topic of intense study in several neurodegenerative conditions, less attention has been placed on changes in monomeric α-synuclein and related physiological consequences on neuronal function. A growing body of evidence supports an important physiological role of α-synuclein in neurotransmission. In the context of traumatic brain injury (TBI), we hypothesized that the regional abundance of soluble monomeric α-synuclein is altered over a chronic time period post-injury. To this end, we evaluated α-synuclein in the cortex, hippocampus, and striatum of adult rats at 6 h, 1 day, 1, 2, 4, and 8 weeks after controlled cortical impact (CCI) injury. Western blot analysis demonstrated decreased levels of monomer α-synuclein protein in the ipsilateral hippocampus at 6 h, 1 day, 1, 2, and 8 weeks, as well as in the ipsilateral cortex at 1 and 2 weeks and in the ipsilateral striatum at 6 h after CCI compared with sham animals. Immunohistochemical analysis revealed lower α-synuclein and a modest reduction in synaptophysin staining in the ipsilateral hippocampus at 1 week after CCI compared with sham animals, with no evidence of intracellular or extracellular α-synuclein aggregates. Collectively, these findings demonstrate that monomeric α-synuclein protein abundance in the hippocampus is reduced over an extensive (acute-to-chronic) post-injury interval. This deficit may contribute to the chronically impaired neurotransmission known to occur after TBI.

3,6'-dithiopomalidomide reduces neural loss, inflammation, behavioral deficits in brain injury and microglial activation

Traumatic brain injury (TBI) causes mortality and disability worldwide. It can initiate acute cell death followed by secondary injury induced by microglial activation, oxidative stress, inflammation and autophagy in brain tissue, resulting in cognitive and behavioral deficits. We evaluated a new pomalidomide (Pom) analog, 3,6'-dithioPom (DP), and Pom as immunomodulatory agents to mitigate TBI-induced cell death, neuroinflammation, astrogliosis and behavioral impairments in rats challenged with controlled cortical impact TBI. Both agents significantly reduced the injury contusion volume and degenerating neuron number evaluated histochemically and by MRI at 24 hr and 7 days, with a therapeutic window of 5 hr post-injury. TBI-induced upregulated markers of microglial activation, astrogliosis and the expression of pro-inflammatory cytokines, iNOS, COX-2, and autophagy-associated proteins were suppressed, leading to an amelioration of behavioral deficits with DP providing greater efficacy. Complementary animal and cellular studies demonstrated DP and Pom mediated reductions in markers of neuroinflammation and α-synuclein-induced toxicity.

Mesenchymal stem cell therapy alleviates the neuroinflammation associated with acquired brain injury

Ischemic stroke and traumatic brain injury (TBI) comprise two particularly prevalent and costly examples of acquired brain injury (ABI). Following stroke or TBI, primary cell death and secondary cell death closely model disease progression and worsen outcomes. Mounting evidence indicates that long‐term neuroinflammation extensively exacerbates the secondary deterioration of brain structure and function. Due to their immunomodulatory and regenerative properties, mesenchymal stem cell transplants have emerged as a promising approach to treating this facet of stroke and TBI pathology. In this review, we summarize the classification of cell death in ABI and discuss the prominent role of inflammation. We then consider the efficacy of bone marrow–derived mesenchymal stem/stromal cell (BM‐MSC) transplantation as a therapy for these injuries. Finally, we examine recent laboratory and clinical studies utilizing transplanted BM‐MSCs as antiinflammatory and neurorestorative treatments for stroke and TBI. Clinical trials of BM‐MSC transplants for stroke and TBI support their promising protective and regenerative properties. Future research is needed to allow for better comparison among trials and to elaborate on the emerging area of cell‐based combination treatments.

Biological links between traumatic brain injury and Parkinson's disease

Parkinson's Disease (PD) is a progressive neurodegenerative disorder with no cure. Clinical presentation is characterized by postural instability, resting tremors, and gait problems that result from progressive loss of A9 dopaminergic neurons in the substantia nigra pars compacta. Traumatic brain injury (TBI) has been implicated as a risk factor for several neurodegenerative diseases, but the strongest evidence is linked to development of PD. Mild TBI (mTBI), is the most common and is defined by minimal, if any, loss of consciousness and the absence of significant observable damage to the brain tissue. mTBI is responsible for a 56% higher risk of developing PD in U.S. Veterans and the risk increases with severity of injury. While the mounting evidence from human studies suggests a link between TBI and PD, fundamental questions as to whether TBI nucleates PD pathology or accelerates PD pathology in vulnerable populations remains unanswered. Several promising lines of research point to inflammation, metabolic dysregulation, and protein accumulation as potential mechanisms through which TBI can initiate or accelerate PD. Amyloid precursor protein (APP), alpha synuclein (α-syn), hyper-phosphorylated Tau, and TAR DNA-binding protein 43 (TDP-43), are some of the most frequently reported proteins upregulated following a TBI and are also closely linked to PD. Recently, upregulation of Leucine Rich Repeat Kinase 2 (LRRK2), has been found in the brain of mice following a TBI. Subset of Rab proteins were identified as biological substrates of LRRK2, a protein also extensively linked to late onset PD. Inhibition of LRRK2 was found to be neuroprotective in PD and TBI models. The goal of this review is to survey current literature concerning the mechanistic overlap between TBI and PD with a particular focus on inflammation, metabolic dysregulation, and aforementioned proteins. This review will also cover the application of rodent TBI models to further our understanding of the relationship between TBI and PD.

Serum α-synuclein and IL-1β are increased and correlated with measures of disease severity in children with epilepsy: potential prognostic biomarkers?

BACKGROUND

The search for noninvasive biomarkers of neuroinflammation and neurodegeneration has focused on various neurological disorders, including epilepsy. We sought to determine whether α-synuclein and cytokines are correlated with the degree of neuroinflammation and/or neurodegeneration in children with epilepsy and with acquired demyelinating disorders of the central nervous system (CNS), as a prototype of autoimmune neuroinflammatory disorders.

METHODS

We analyzed serum and exosome levels of α-synuclein and serum proinflammatory and anti-inflammatory cytokines among 115 children with epilepsy and 10 acquired demyelinating disorders of the CNS and compared to 146 controls. Patients were enrolled prospectively and blood was obtained from patients within 48 h after acute afebrile seizure attacks or relapse of neurological symptoms. Acquired demyelinating disorders of the CNS include acute disseminated encephalomyelitis, multiple sclerosis, neuromyelitis optica spectrum disorders, and transverse myelitis. The controls were healthy age-matched children. The serum exosomes were extracted with ExoQuick exosome precipitation solution. Serum α-synuclein levels and serum levels of cytokines including IFN-β, IFN-γ, IL-1β, IL-6, IL-10 and TNF-α were measured using single and multiplex ELISA kits. Data were analyzed and compared with measures of disease severity, such as age at disease onset, duration of disease, and numbers of antiepileptic drug in use.

RESULTS

Serum α-synuclein levels were significantly increased in patients with epilepsy and acquired demyelinating disorders of the CNS compared to controls (both, p < 0.05) and showed correlation with measures of disease severity both in epilepsy (p < 0.05, r = 0.2132) and in acquired demyelinating disorders of the CNS (p < 0.05, r = 0.5892). Exosome α-synuclein showed a significant correlation with serum α-synuclein (p < 0.0001, r = 0.5915). Serum IL-1β levels were correlated only with the numbers of antiepileptic drug used in children with epilepsy (p < 0.001, r = 0.3428), suggesting drug resistant epilepsy.

CONCLUSIONS

This is the first study in children demonstrating that serum α-synuclein levels were significantly increased in children with epilepsy and with acquired demyelinating disorders of the CNS and correlated with measures of disease severity. Serum IL-1β levels showed significant correlation only with drug resistance in children with epilepsy. Thus, these data support that serum levels of α-synuclein and IL-1β are potential prognostic biomarkers for disease severity in children with epilepsy. CNS, central nervous system.

Collection and Analyses of Cerebrospinal Fluid for Pediatric Translational Research

Cerebrospinal fluid sample collection and analysis is imperative to better elucidate central nervous system injury and disease in children. Sample collection methods are varied and carry with them certain ethical and biologic considerations, complications, and contraindications. Establishing best practices for sample collection, processing, storage, and transport will ensure optimal sample quality. Cerebrospinal fluid samples can be affected by a number of factors including subject age, sampling method, sampling location, volume extracted, fraction, blood contamination, storage methods, and freeze-thaw cycles. Indicators of sample quality can be assessed by matrix-associated laser desorption/ionization time-of-flight mass spectrometry and include cystatin C fragments, oxidized proteins, prostaglandin D synthase, and evidence of blood contamination. Precise documentation of sample collection processes and the establishment of meticulous handling procedures are essential for the creation of clinically relevant biospecimen repositories. In this review we discuss the ethical considerations and best practices for cerebrospinal fluid collection, as well as the influence of preanalytical factors on cerebrospinal fluid analyses. Cerebrospinal fluid biomarkers in highly researched pediatric diseases or disorders are discussed.

Sex Differences in Traumatic Brain Injury: What We Know and What We Should Know

There is growing recognition of the problem of male bias in neuroscience research, including in the field of traumatic brain injury (TBI) where fewer women than men are recruited to clinical trials and male rodents have predominantly been used as an experimental injury model. Despite TBI being a leading cause of mortality and disability worldwide, sex differences in pathophysiology and recovery are poorly understood, limiting clinical care and successful drug development. Given growing interest in sex as a biological variable affecting injury outcomes and treatment efficacy, there is a clear need to summarize sex differences in TBI. This scoping review presents an overview of current knowledge of sex differences in TBI and a comparison of human and animal studies. We found that overall, human studies report worse outcomes in women than men, whereas animal studies report better outcomes in females than males. However, closer examination shows that multiple factors including injury severity, sample size, and experimental injury model may differentially interact with sex to affect TBI outcomes. Additionally, we explore how sex differences in mitochondrial structure and function might contribute to possible sex differences in TBI outcomes. We propose recommendations for future investigations of sex differences in TBI, which we hope will lead to improved patient management, prognosis, and translation of therapies from bench to bedside.

Novel therapies for combating chronic neuropathological sequelae of TBI

Traumatic brain injury (TBI) is a risk factor for development of chronic neurodegenerative disorders later in life. This review summarizes the current knowledge and concepts regarding the connection between long-term consequences of TBI and aging-associated neurodegenerative disorders including Alzheimer's disease (AD), chronic traumatic encephalopathy (CTE), and Parkinsonism, with implications for novel therapy targets. Several aggregation-prone proteins such as the amyloid-beta (Aβ) peptides, tau proteins, and α-synuclein protein are involved in secondary pathogenic cascades initiated by a TBI and are also major building blocks of the hallmark pathological lesions in chronic human neurodegenerative diseases with dementia. Impaired metabolism and degradation pathways of aggregation-prone proteins are discussed as potentially critical links between the long-term aftermath of TBI and chronic neurodegeneration. Utility and limitations of previous and current preclinical TBI models designed to study the link between TBI and chronic neurodegeneration, and promising intervention pharmacotherapies and non-pharmacologic strategies to break this link, are also summarized. Complexity of long-term neuropathological consequences of TBI is discussed, with a goal of guiding future preclinical studies and accelerating implementation of promising therapeutics into clinical trials. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury".

Investigating ioflupane I123 injection and single photon emission tomography as an imaging biomarker for long-term sequelae following mild traumatic brain injury

OBJECTIVE

To determine whether there were differences in clinical outcomes for ioflupane I¹²³ injection (DaTscan) and single photon emission tomography consistent with early Parkinson's disease (PD) among individuals with a history of mild traumatic brain injury (mTBI).

METHODS

We performed a case-control study among patients presenting to the Emergency Room (ER) during 2006-2013 with mTBI (cases, n = 34) or without mTBI (controls, n = 33). We performed clinical and imaging measurements in cases and controls at least 1-year post-presentation to the ER (average three years four months).

RESULTS

All DaTscans obtained were qualitatively normal. There were no qualitative DaTscan differences between cases and controls. There was, however, a significant increase in caudate asymmetry in controls versus cases (p = 0.02), but this finding was no longer significant after correction for multiple comparisons. There was a suggestion of a trend of poorer clinical score test measures among those with mTBI, although the overall mean score difference between cases and controls was not clinically significant.

CONCLUSION

Our small study does not provide support for DaTscan changes suggestive of PD in the one to seven years following mTBI. A trend towards poorer clinical measures was seen but was not clinically relevant in our small sample. Further work in a large population is necessary to support these findings.

Neuroinflammation in traumatic brain injury: A chronic response to an acute injury

Every year, approximately 1.4 million US citizens visit emergency rooms for traumatic brain injuries. Formerly known as an acute injury, chronic neurodegenerative symptoms such as compromised motor skills, decreased cognitive abilities, and emotional and behavioral changes have caused the scientific community to consider chronic aspects of the disorder. The injury causing impact prompts multiple cell death processes, starting with neuronal necrosis, and progressing to various secondary cell death mechanisms. Secondary cell death mechanisms, including excitotoxicity, oxidative stress, mitochondrial dysfunction, blood-brain barrier disruption, and inflammation accompany chronic traumatic brain injury (TBI) and often contribute to long-term disabilities. One hallmark of both acute and chronic TBI is neuroinflammation. In acute stages, neuroinflammation is beneficial and stimulates an anti-inflammatory response to the damage. Conversely, in chronic TBI, excessive inflammation stimulates the aforementioned secondary cell death. Converting inflammatory cells from pro-inflammatory to anti-inflammatory may expand the therapeutic window for treating TBI, as inflammation plays a role in all stages of the injury. By expanding current research on the role of inflammation in TBI, treatment options and clinical outcomes for afflicted individuals may improve. This paper is a review article. Referred literature in this paper has been listed in the references section. The data sets supporting the conclusions of this article are available online by searching various databases, including PubMed. Some original points in this article come from the laboratory practice in our research center and the authors' experiences.

Hypothermia for traumatic brain injury

BACKGROUND

Hypothermia has been used in the treatment of brain injury for many years. Encouraging results from small trials and laboratory studies led to renewed interest in the area and some larger trials.

OBJECTIVES

To determine the effect of mild hypothermia for traumatic brain injury (TBI) on mortality, long-term functional outcomes and complications.

SEARCH METHODS

We ran and incorporated studies from database searches to 21 March 2016. We searched the Cochrane Injuries Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE (OvidSP), Embase Classic+Embase (OvidSP), PubMed, ISI Web of science (SCI-EXPANDED, SSCI, CPCI-S & CPSI-SSH), clinical trials registers, and screened reference lists. We also re-ran these searches pre-publication in June 2017; the result from this search is presented in 'Studies awaiting classification'.

SELECTION CRITERIA

We included randomised controlled trials of participants with closed TBI requiring hospitalisation who were treated with hypothermia to a maximum of 35 ºC for at least 12 consecutive hours. Treatment with hypothermia was compared to maintenance with normothermia (36.5 to 38 ºC).

DATA COLLECTION AND ANALYSIS

Two review authors assessed data on mortality, unfavourable outcomes according to the Glasgow Outcome Scale, and pneumonia.

MAIN RESULTS

We included 37 eligible trials with a total of 3110 randomised participants; nine of these were new studies since the last update (2009) and five studies had been previously excluded but were re-assessed and included during the 2017 update. We identified two ongoing studies from searches of clinical trials registers and database searches and two studies await classification.Studies included both adults and children with TBI. Most studies commenced treatment immediately on admission to hospital or after craniotomies and all treatment was maintained for at least 24 hours. Thirty-three studies reported data for mortality, 31 studies reported data for unfavourable outcomes (death, vegetative state or severe disability), and 14 studies reported pneumonia. Visual inspection of the results for these outcomes showed inconsistencies among studies, with differences in the direction of effect, and we did not pool these data for meta-analysis. We considered duration of hypothermia therapy and the length of follow-up in collected data for these subgroups; differences in study data remained such that we did not perform meta-analysis.Studies were generally poorly reported and we were unable to assess risk of bias adequately. Heterogeneity was evident both in the trial designs and participant inclusion. Inconsistencies in results may be explained by heterogeneity among study participants or bias introduced by individual study methodology but we did not explore this in detail in subgroup or sensitivity analyses. We used the GRADE approach to judge the quality of the evidence for each outcome and downgraded the evidence for mortality and unfavourable outcome to very low. We downgraded the evidence for the pneumonia outcome to low.

AUTHORS' CONCLUSIONS

Despite a large number studies, there remains no high-quality evidence that hypothermia is beneficial in the treatment of people with TBI. Further research, which is methodologically robust, is required in this field to establish the effect of hypothermia for people with TBI.

When friend turns foe: central and peripheral neuroinflammation in central nervous system injury

Injury to the central nervous system (CNS) is common, and though it has been well studied, many aspects of traumatic brain injury (TBI) and stroke are poorly understood. TBI and stroke are two pathologic events that can cause severe, immediate impact to the neurostructure and function of the CNS, which has been recognized recently to be exacerbated by the body’s own immune response. Although the brain damage induced by the initial trauma is most likely unsalvageable, the secondary immunologic deterioration of neural tissue gives ample opportunity for therapeutic strategists seeking to mitigate TBI’s secondary detrimental effects. The purpose of this paper is to highlight the cell death mechanisms associated with CNS injury with special emphasis on inflammation. The authors discuss sources of inflammation, and introduce the role of the spleen in the systemic response to inflammation after CNS injury.

Moderate traumatic brain injury increases the vulnerability to neurotoxicity induced by systemic administration of 6-hydroxydopamine in mice

Moderate traumatic brain injury (TBI) might increase the vulnerability to neuronal neurodegeneration, but the basis of such selective neuronal susceptibility has remained elusive. In keeping with the disruption of the blood-brain barrier (BBB) caused by TBI, changes in BBB permeability following brain injury could facilitate the access of xenobiotics into the brain. To test this hypothesis, here we evaluated whether TBI would increase the susceptibility of nigrostriatal dopaminergic fibers to the systemic administration of 6-hydroxydopamine (6-OHDA), a classic neurotoxin used to trigger a PD-like phenotype in mice, but that in normal conditions is unable to cross the BBB. Adult Swiss mice were submitted to a moderate TBI using a free weight-drop device and, 5h later, they were injected intraperitoneally with a single dose of 6-OHDA (100mg/kg). Afterwards, during a period of 4weeks, the mice were submitted to a battery of behavioral tests, including the neurological severity score (NSS), the open field and the rotarod. Animals from the TBI plus 6-OHDA group displayed significant motor and neurological impairments that were improved by acute l-DOPA administration (25mg/kg, i.p.). Moreover, the observation of the motor deficits correlates with (i) a significant decrease in the tyrosine hydroxylase levels mainly in the rostral striatum and (ii) a significant increase in the levels of striatal glial fibrillary acidic protein (GFAP) levels. On the whole, the present findings demonstrate that a previous moderate TBI event increases the susceptibility to motor, neurological and neurochemical alterations induced by systemic administration of the dopaminergic neurotoxin 6-OHDA in mice.

Reducing synuclein accumulation improves neuronal survival after spinal cord injury

Spinal cord injury causes neuronal death, limiting subsequent regeneration and recovery. Thus, there is a need to develop strategies for improving neuronal survival after injury. Relative to our understanding of axon regeneration, comparatively little is known about the mechanisms that promote the survival of damaged neurons. To address this, we took advantage of lamprey giant reticulospinal neurons whose large size permits detailed examination of post-injury molecular responses at the level of individual, identified cells. We report here that spinal cord injury caused a select subset of giant reticulospinal neurons to accumulate synuclein, a synaptic vesicle-associated protein best known for its atypical aggregation and causal role in neurodegeneration in Parkinson's and other diseases. Post-injury synuclein accumulation took the form of punctate aggregates throughout the somata and occurred selectively in dying neurons, but not in those that survived. In contrast, another synaptic vesicle protein, synaptotagmin, did not accumulate in response to injury. We further show that the post-injury synuclein accumulation was greatly attenuated after single dose application of either the "molecular tweezer" inhibitor, CLR01, or a translation-blocking synuclein morpholino. Consequently, reduction of synuclein accumulation not only improved neuronal survival, but also increased the number of axons in the spinal cord proximal and distal to the lesion. This study is the first to reveal that reducing synuclein accumulation is a novel strategy for improving neuronal survival after spinal cord injury.

Alpha-synuclein as a pathological link between chronic traumatic brain injury and Parkinson's disease

The long-term consequences of traumatic brain injury (TBI) are closely associated with the development of histopathological deficits. Notably, TBI may predispose long-term survivors to age-related neurodegenerative diseases, such as Parkinson's disease (PD), which is characterized by a gradual degeneration of the nigrostriatal dopaminergic neurons. However, preclinical studies on the pathophysiological changes in substantia nigra (SN) after chronic TBI are lacking. In the present in vivo study, we examined the pathological link between PD-associated dopaminergic neuronal loss and chronic TBI. Sixty days post-TBI, rats were euthanized and brain tissues harvested. Immunostaining was performed using tyrosine hydroxylase (TH), an enzyme required for the synthesis of dopamine in neurons, α-synuclein, a presynaptic protein that plays a role in synaptic vesicle recycling, and major histocompatibility complex II (MHCII), a protein found in antigen presenting cells such as inflammatory microglia cells, all key players in PD pathology. Unbiased stereology analyses revealed significant decrease of TH-positive expression in the surviving dopaminergic neurons of the SN pars compacta (SNpc) relative to sham control. In parallel, increased α-synuclein accumulation was detected in the ipsilateral SN compared to the contralateral SN in TBI animals or sham control. In addition, exacerbation of MHCII+ cells was recognized in the SN and cerebral peduncle ipsilateral to injury relative to contralateral side and sham control. These results suggest α-synuclein as a pathological link between chronic effects of TBI and PD symptoms as evidenced by significant overexpression and abnormal accumulation of α-synuclein in inflammation-infiltrated SN of rats exposed to chronic TBI. J. Cell. Physiol. 230: 1024–1032, 2015. © 2014 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc.

Brain injury biomarkers as outcome predictors in pediatric severe traumatic brain injury

BACKGROUND

To systematically review the literature on brain injury biomarkers, defined as any injury biomarker detected in cerebrospinal fluid (CSF) or blood injury biomarkers primarily expressed in the brain parenchyma, to determine outcome prediction in pediatric severe traumatic brain injury (sTBI).

METHODS

A search of MEDLINE(®), EMBASE(®), PsycINFO(®), Pubmed(®), and the Cochrane Database, as well as grey literature sources, personal contacts, hand searches, and reference lists. The search terms used were traumatic brain injury, biomarkers, prognosis, and children. No language, publication type, or publication date restrictions were imposed. All articles were critically reviewed by two clinicians independently.

RESULTS

A total of 7,150 articles were identified initially with 16 studies identified for review. Eighteen different biomarkers were examined; 11 in CSF and 7 in blood. Outcomes assessed included either in-hospital mortality or functional state (hospital discharge, 3-months or 6-months; Glasgow Outcome Scale or Pediatric Cerebral Performance Category). Significant correlations were established between sTBI outcomes and various biomarkers in CSF (IL-6, IL-8, IL-1β, S100β, NGF, NSE, DCX, ET-1, HMGB-1, cytochrome C) and blood (GFAP, NF-H, UCH-L1, SBDP-145, leptin). Mixed results were obtained for blood S100β. Outcome did not correlate with several biomarkers in either CSF (BDNF, GDNF, α-Syn) or blood (NSE, MBP). The Class of Evidence was considered II in 1 study and III in the remaining 15 studies.

CONCLUSIONS

Based on the status of current sTBI biomarker research, we recommend that future research should be directed at both novel biomarker discovery and validation of biomarker panels in large, well-designed longitudinal studies.

Neuroinflammatory responses to traumatic brain injury: etiology, clinical consequences, and therapeutic opportunities

Traumatic brain injury (TBI) is a serious public health problem accounting for 1.4 million emergency room visits by US citizens each year. Although TBI has been traditionally considered an acute injury, chronic symptoms reminiscent of neurodegenerative disorders have now been recognized. These progressive neurodegenerative-like symptoms manifest as impaired motor and cognitive skills, as well as stress, anxiety, and mood affective behavioral alterations. TBI, characterized by external bumps or blows to the head exceeding the brain's protective capacity, causes physical damage to the central nervous system with accompanying neurological dysfunctions. The primary impact results in direct neural cell loss predominantly exhibiting necrotic death, which is then followed by a wave of secondary injury cascades including excitotoxicity, oxidative stress, mitochondrial dysfunction, blood-brain barrier disruption, and inflammation. All these processes exacerbate the damage, worsen the clinical outcomes, and persist as an evolving pathological hallmark of what we now describe as chronic TBI. Neuroinflammation in the acute stage of TBI mobilizes immune cells, astrocytes, cytokines, and chemokines toward the site of injury to mount an antiinflammatory response against brain damage; however, in the chronic stage, excess activation of these inflammatory elements contributes to an "inflamed" brain microenvironment that principally contributes to secondary cell death in TBI. Modulating these inflammatory cells by changing their phenotype from proinflammatory to antiinflammatory would likely promote therapeutic effects on TBI. Because neuroinflammation occurs at acute and chronic stages after the primary insult in TBI, a treatment targeting neuroinflammation may have a wider therapeutic window for TBI. To this end, a better understanding of TBI etiology and clinical manifestations, especially the pathological presentation of chronic TBI with neuroinflammation as a major component, will advance our knowledge on inflammation-based disease mechanisms and treatments.

Increased DJ-1 in urine exosome of Korean males with Parkinson's disease

Parkinson's disease (PD) is a difficult disease to diagnose although it is the second most common neurodegenerative disease. Recent studies show that exosome isolated from urine contains LRRK2 or DJ-1, proteins whose mutations cause PD. To investigate a potential use for urine exosomes as a tool for PD diagnosis, we compared levels of LRRK2, α-synuclein, and DJ-1 in urine exosomes isolated from Korean PD patients and non-PD controls. LRRK2 and DJ-1, but not α-synuclein, were detected in the urine exosome samples, as reported previously. We initially could not detect any significant difference in these protein levels between the patient and the control groups. However, when age, disease duration, L-dopa daily dose, and gender were considered as analytical parameters, LRRK2 and DJ-1 protein levels showed clear gender-dependent differences. In addition, DJ-1 level was significantly higher (1.7-fold) in male patients with PD than that in male non-PD controls and increased in an age-dependent manner in male patients with PD. Our observation might provide a clue to lead to a novel biomarker for PD diagnosis, at least in males.

Traumatic brain injury dysregulates microRNAs to modulate cell signaling in rat hippocampus

Traumatic brain injury (TBI) is a common cause for cognitive and communication problems, but the molecular and cellular mechanisms are not well understood. Epigenetic modifications, such as microRNA (miRNA) dysregulation, may underlie altered gene expression in the brain, especially hippocampus that plays a major role in spatial learning and memory and is vulnerable to TBI. To advance our understanding of miRNA in pathophysiological processes of TBI, we carried out a time-course microarray analysis of microRNA expression profile in rat ipsilateral hippocampus and examined histological changes, apoptosis and synapse ultrastructure of hippocampus post moderate TBI. We found that 10 out of 156 reliably detected miRNAs were significantly and consistently altered from one hour to seven days after injury. Bioinformatic and gene ontology analyses revealed 107 putative target genes, as well as several biological processes that might be initiated by those dysregulated miRNAs. Among those differentially expressed microRNAs, miR-144, miR-153 and miR-340-5p were confirmed to be elevated at all five time points after TBI by quantitative RT-PCR. Western blots showed three of the predicated target proteins, calcium/calmodulin-dependent serine protein kinase (CASK), nuclear factor erythroid 2-related factor 2 (NRF2) and alpha-synuclein (SNCA), were concurrently down- regulated, suggesting that miR-144, miR-153 and miR-340-5p may play important roles collaboratively in the pathogenesis of TBI-induced cognitive and memory impairments. These microRNAs might serve as potential targets for progress assessment and intervention against TBI to mitigate secondary damage to the brain.

Neurochemical profile of dementia pugilistica

Dementia pugilistica (DP), a suite of neuropathological and cognitive function declines after chronic traumatic brain injury (TBI), is present in approximately 20% of retired boxers. Epidemiological studies indicate TBI is a risk factor for neurodegenerative disorders including Alzheimer disease (AD) and Parkinson disease (PD). Some biochemical alterations observed in AD and PD may be recapitulated in DP and other TBI persons. In this report, we investigate long-term biochemical changes in the brains of former boxers with neuropathologically confirmed DP. Our experiments revealed biochemical and cellular alterations in DP that are complementary to and extend information already provided by histological methods. ELISA and one-dimensional and two dimensional Western blot techniques revealed differential expression of select molecules between three patients with DP and three age-matched non-demented control (NDC) persons without a history of TBI. Structural changes such as disturbances in the expression and processing of glial fibrillary acidic protein, tau, and α-synuclein were evident. The levels of the Aβ-degrading enzyme neprilysin were reduced in the patients with DP. Amyloid-β levels were elevated in the DP participant with the concomitant diagnosis of AD. In addition, the levels of brain-derived neurotrophic factor and the axonal transport proteins kinesin and dynein were substantially decreased in DP relative to NDC participants. Traumatic brain injury is a risk factor for dementia development, and our findings are consistent with permanent structural and functional damage in the cerebral cortex and white matter of boxers. Understanding the precise threshold of damage needed for the induction of pathology in DP and TBI is vital.

Increased CSF concentrations of myelin basic protein after TBI in infants and children: absence of significant effect of therapeutic hypothermia

BACKGROUND

The objectives of this study were to determine effects of severe traumatic brain injury (TBI) on cerebrospinal fluid (CSF) concentrations of myelin basic protein (MBP) and to assess relationships between clinical variables and CSF MBP concentrations.

METHODS

We measured serial CSF MBP concentrations in children enrolled in a randomized controlled trial evaluating therapeutic hypothermia (TH) after severe pediatric TBI. Control CSF was obtained from children evaluated, but found not to be having CNS infection. Generalized estimating equation models and Wilcoxon Rank-Sum test were used for comparisons of MBP concentrations.

RESULTS

There were 27 TBI cases and 57 controls. Overall mean (± SEM) TBI case MBP concentrations for 5 days after injury were markedly greater than controls (50.49 ± 6.97 vs. 0.11 ± 0.01 ng/ml, p < 0.01). Mean MBP concentrations were lower in TBI patients <1 year versus >1 year (9.18 ± 1.67 vs. 60.22 ± 8.26 ng/ml, p = 0.03), as well as in cases with abusive head trauma (AHT) versus non-abusive TBI (14.46 ± 3.15 vs. 61.17 ± 8.65 ng/ml, p = 0.03). TH did not affect MBP concentrations.

CONCLUSIONS

Mean CSF MBP increases markedly after severe pediatric TBI, but is not affected by TH. Infancy and AHT are associated with low MBP concentrations, suggesting that age-dependent myelination influences MBP concentrations after injury. Given the magnitude of MBP increases, axonal injury likely represents an important therapeutic target in pediatric TBI.

The potential for bio-mediators and biomarkers in pediatric traumatic brain injury and neurocritical care

The use of biomarkers of brain injury in pediatric neurocritical care has been explored for at least 15 years. Two general lines of research on biomarkers in pediatric brain injury have been pursued: (1) studies of "bio-mediators" in cerebrospinal fluid (CSF) of children after traumatic brain injury (TBI) to explore the components of the secondary injury cascades in an attempt to identify potential therapeutic targets and (2) studies of the release of structural proteins into the CSF, serum, or urine in order to diagnose, monitor, and/or prognosticate in patients with TBI or other pediatric neurocritical care conditions. Unique age-related differences in brain biology, disease processes, and clinical applications mandate the development and testing of brain injury bio-mediators and biomarkers specifically in pediatric neurocritical care applications. Finally, although much of the early work on biomarkers of brain injury in pediatrics has focused on TBI, new applications are emerging across a wide range of conditions specifically for pediatric neurocritical care including abusive head trauma, cardiopulmonary arrest, septic shock, extracorporeal membrane oxygenation, hydrocephalus, and cardiac surgery. The potential scope of the utility of biomarkers in pediatric neurocritical care is thus also discussed.

Triggering of inflammasome by aggregated α-synuclein, an inflammatory response in synucleinopathies

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases. It is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta of the brain. Another feature is represented by the formation in these cells of inclusions called Lewy bodies (LB), principally constituted by fibrillar α-synuclein (αSyn). This protein is considered a key element in the aetiology of a group of neurodegenerative disorders termed synucleinopathies, which include PD, but the cellular and molecular mechanisms involved are not completely clear. It is established that the inflammatory process plays a crucial role in the pathogenesis and/or progression of PD; moreover, it is known that aggregated αSyn, released by neurons, activates microglia cells to produce pro-inflammatory mediators, such as IL-1β. IL-1β is one of the strongest pro-inflammatory cytokines; it is produced as an inactive mediator, and its maturation and activation requires inflammasome activation. In particular, the NLRP3 inflammasome is activated by a wide variety of stimuli, among which are crystallized and particulate material. In this work, we investigated the possibility that IL-1β production, induced by fibrillar αSyn, is involved the inflammasome activation. We demonstrated the competence of monomeric and fibrillar αSyn to induce synthesis of IL-1β, through TLR2 interaction; we found that the secretion of the mature cytokine was a peculiarity of the fibrillated protein. Moreover, we observed that the secretion of IL-1β involves NLRP3 inflammasome activation. The latter relies on the phagocytosis of fibrillar αSyn, followed by increased ROS production and cathepsin B release into the cytosol. Taken together, our data support the notion that fibrillar αSyn, likely released by neuronal degeneration, acts as an endogenous trigger inducing a strong inflammatory response in PD.

Basis for the use of localized hypothermia during radical pelvic surgery

Controlled tissue cooling, or hypothermia, has been used therapeutically for decades to mitigate the negative effects of traumatic, ischemic, and surgical insults. When applied systemically, moderate hypothermia can attenuate or prevent the extent of neurologic sequelae. Localized hypothermia, on the other hand, has the capacity to reduce tissue edema, suppress inflammation, and minimize the severity of peripheral nerve injury. Therapeutic hypothermia has been used in critical care, neurosurgery, ophthalmology, otolaryngology, cardiothoracic surgery and most recently in urology. Nerve injury during radical pelvic surgery can result in urinary incontinence or retention, impotence and bowel dysfunction. Localized hypothermia during radical prostatectomy has demonstrated improved recovery of urinary continence and erectile function, and similar benefits might be observed in other types of radical pelvic surgery.

Quo vadis 2010? - carpe diem: challenges and opportunities in pediatric traumatic brain injury

Traumatic brain injury (TBI) in infants and children remains a public health problem of enormous magnitude. It is a complex and heterogeneous condition that presents many diagnostic, therapeutic and prognostic challenges. A number of investigative teams are studying pediatric TBI both in experimental models and in clinical studies at the bedside. This review builds on work presented in a prior supplement to Developmental Neuroscience that was published in 2006, and addresses several active areas of research on this topic, including (1) the application of novel imaging methods, (2) the use of serum and/or CSF biomarkers of injury, (3) advances in neuromonitoring, (4) the development and testing of novel therapies, (5) developments in modeling pediatric TBI, (6) the consideration of a new approach to classification of pediatric TBI, and (7) assessing the potential impact of the development of pediatric and neonatal neurocritical care services on the management and outcome of pediatric TBI.