Traumatic brain injury: physiology, mechanisms, and outcome

Mortality Predictors for Adult Patients with Mild-to-Moderate Traumatic Brain Injury: A Literature Review

Traumatic brain injuries (TBIs) represent a significant public health concern, with mild-to-moderate cases comprising a substantial portion of incidents. Understanding the predictors of mortality among adult patients with mild-to-moderate TBIs is crucial for optimizing clinical management and improving outcomes. This literature review examines the existing research to identify and analyze the mortality predictors in this patient population. Through a comprehensive review of peer-reviewed articles and clinical studies, key prognostic factors, such as age, Glasgow Coma Scale (GCS) score, the presence of intracranial hemorrhage, pupillary reactivity, and coexisting medical conditions, are explored. Additionally, this review investigates the role of advanced imaging modalities, biomarkers, and scoring systems in predicting mortality following a mild-to-moderate TBI. By synthesizing the findings from diverse studies, this review aims to provide clinicians and researchers with valuable insights into the factors influencing mortality outcomes in adult patients with a mild-to-moderate TBI, thus facilitating more informed decision making and targeted interventions in clinical practice.

Clinical Management in Traumatic Brain Injury

Traumatic brain injury is one of the leading causes of morbidity and mortality worldwide and is one of the major public healthcare burdens in the US, with millions of patients suffering from the traumatic brain injury itself (approximately 1.6 million/year) or its repercussions (2-6 million patients with disabilities). The severity of traumatic brain injury can range from mild transient neurological dysfunction or impairment to severe profound disability that leaves patients completely non-functional. Indications for treatment differ based on the injury's severity, but one of the goals of early treatment is to prevent secondary brain injury. Hemodynamic stability, monitoring and treatment of intracranial pressure, maintenance of cerebral perfusion pressure, support of adequate oxygenation and ventilation, administration of hyperosmolar agents and/or sedatives, nutritional support, and seizure prophylaxis are the mainstays of medical treatment for severe traumatic brain injury. Surgical management options include decompressive craniectomy or cerebrospinal fluid drainage via the insertion of an external ventricular drain. Several emerging treatment modalities are being investigated, such as anti-excitotoxic agents, anti-ischemic and cerebral dysregulation agents, S100B protein, erythropoietin, endogenous neuroprotectors, anti-inflammatory agents, and stem cell and neuronal restoration agents, among others.

Therapeutic effects of anti-diabetic drugs on traumatic brain injury

AIMS

In this narrative review, we have analyzed and synthesized current studies relating to the effects of anti-diabetic drugs on traumatic brain injury (TBI) complications.

METHODS

Eligible studies were collected from Scopus, Google Scholar, PubMed, and Cochrane Library for clinical, in-vivo, and in-vitro studies published on the impact of anti-diabetic drugs on TBI.

RESULTS

Traumatic brain injury (TBI) is a serious brain disease that is caused by any type of trauma. The pathophysiology of TBI is not yet fully understood, though physical injury and inflammatory events have been implicated in TBI progression. Several signaling pathways are known to play pivotal roles in TBI injuries, including Nuclear factor erythroid 2-related factor 2 (Nrf2), High mobility group box 1 protein/Nuclear factor kappa B (HMGB1/NF-κB), Adiponectin, Mammalian Target of Rapamycin (mTOR), Toll-Like Receptor (TLR), Wnt/β-catenin, Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT), Nod-like receptor protein3 (NLRP3) inflammasome, Phosphoglycerate kinase 1/Kelch-like ECH-associated protein 1 (PGK1/KEAP1)/Nrf2, and Mitogen-activated protein kinase (MAPK) . Recent studies suggest that oral anti-diabetic drugs such as biguanides, thiazolidinediones (TZDs), sulfonylureas (SUs), sodium-glucose cotransporter-2 inhibitors (SGLT2is), dipeptidyl peptidase-4 inhibitors (DPPIs), meglitinides, and alpha-glucosidase inhibitors (AGIs) could have beneficial effects in the management of TBI complications. These drugs may downregulate the inflammatory pathways and induce antioxidant signaling pathways, thus alleviating complications of TBI.

CONCLUSION

Based on this comprehensive literature review, antidiabetic medications might be considered in the TBI treatment protocol. However, evidence from clinical trials in patients with TBI is still warranted.

Insights from Rodent Models for Improving Bench-to-Bedside Translation in Traumatic Brain Injury

Road accidents, domestic falls, and persons associated with sports and military services exhibited the concussion or contusion type of traumatic brain injury (TBI) that resulted in chronic traumatic encephalopathy. In some instances, these complex neurological aberrations pose severe brain damage and devastating long-term neurological sequelae. Several preclinical (rat and mouse) TBI models simulate the clinical TBI endophenotypes. Moreover, many investigational neuroprotective candidates showed promising effects in these models; however, the therapeutic success of these screening candidates has been discouraging at various stages of clinical trials. Thus, a correct selection of screening model that recapitulates the clinical neurobiology and endophenotypes of concussion or contusion is essential. Herein, we summarize the advantages and caveats of different preclinical models adopted for TBI research. We suggest that an accurate selection of experimental TBI models may improve the translational viability of the investigational entity.

Increasing Rigor of Preclinical Research to Maximize Opportunities for Translation

The use of animal models in pre-clinical research has significantly broadened our understanding of the pathologies that underlie traumatic brain injury (TBI)-induced damage and deficits. However, despite numerous pre-clinical studies reporting the identification of promising neurotherapeutics, translation of these therapies to clinical application has so far eluded the TBI research field. A concerted effort to address this lack of translatability is long overdue. Given the inherent heterogeneity of TBI and the replication crisis that continues to plague biomedical research, this is a complex task that will require a multifaceted approach centered around rigor and reproducibility. Here, we discuss the role of three primary focus areas for better aligning pre-clinical research with clinical TBI management. These focus areas are (1) reporting and standardization of protocols, (2) replication of prior knowledge including the confirmation of expected pharmacodynamics, and (3) the broad application of open science through inter-center collaboration and data sharing. We further discuss current efforts that are establishing the core framework needed for successfully addressing the translatability crisis of TBI.

Cdk5 mediates rotational force-induced brain injury

Millions of traumatic brain injuries (TBIs) occur annually. TBIs commonly result from falls, traffic accidents, and sports-related injuries, all of which involve rotational acceleration/deceleration of the brain. During these injuries, the brain endures a multitude of primary insults including compression of brain tissue, damaged vasculature, and diffuse axonal injury. All of these deleterious effects can contribute to secondary brain ischemia, cellular death, and neuroinflammation that progress for weeks, months, and lifetime after injury. While the linear effects of head trauma have been extensively modeled, less is known about how rotational injuries mediate neuronal damage following injury. Here, we developed a new model of repetitive rotational head trauma in rodents and demonstrated acute and prolonged pathological, behavioral, and electrophysiological effects of rotational TBI (rTBI). We identify aberrant Cyclin-dependent kinase 5 (Cdk5) activity as a principal mediator of rTBI. We utilized Cdk5-enriched phosphoproteomics to uncover potential downstream mediators of rTBI and show pharmacological inhibition of Cdk5 reduces the cognitive and pathological consequences of injury. These studies contribute meaningfully to our understanding of the mechanisms of rTBI and how they may be effectively treated.

A Systematic Review on Traumatic Brain Injury Pathophysiology and Role of Herbal Medicines in its Management

BACKGROUND

Traumatic brain injury (TBI) is a worldwide problem. Almost about sixtynine million people sustain TBI each year all over the world. Repetitive TBI linked with increased risk of neurodegenerative disorder such as Parkinson, Alzheimer, traumatic encephalopathy. TBI is characterized by primary and secondary injury and exerts a severe impact on cognitive, behavioral, psychological and other health problem. There were various proposed mechanism to understand complex pathophysiology of TBI but still there is a need to explore more about TBI pathophysiology. There are drugs present for the treatment of TBI in the market but there is still need of more drugs to develop for better and effective treatment of TBI, because no single drug is available which reduces the further progression of this injury.

OBJECTIVE

The main aim and objective of structuring this manuscript is to design, develop and gather detailed data regarding about the pathophysiology of TBI and role of medicinal plants in its treatment.

METHOD

This study is a systematic review conducted between January 1995 to June 2021 in which a consultation of scientific articles from indexed periodicals was carried out in Science Direct, United States National Library of Medicine (Pubmed), Google Scholar, Elsvier, Springer and Bentham.

RESULTS

A total of 54 studies were analyzed, on the basis of literature survey in the research area of TBI.

CONCLUSION

Recent studies have shown the potential of medicinal plants and their chemical constituents against TBI therefore, this review targets the detailed information about the pathophysiology of TBI and role of medicinal plants in its treatment.

Mild traumatic brain injury and sports-related concussion

Mild traumatic brain injury (mTBI) and concussion are equivalent terms for the sequela of injury to the head that disrupts brain functioning. Various forces may be causative from seemingly innocuous bumps to the head resulting from sports-related injuries to more severe blows to the head. However, the postconcussive motor, cognitive, emotional, and psychosocial sequelae can be just as devastating and long lasting, leading to loss of independent function and safe performance of activities. Taken together, they pose a significant challenge to recovery, requiring a multifaceted dynamic rehabilitative strategy. The current systems of health care pose challenges to suboptimal management of sports-related concussion (SRC) that goes beyond the acute injury, and into the school setting, failing to be identified by school staff, and inconsistencies in communicating medical information regarding school modifications, follow-up health services, or concussion-related educational services. Children who sustain SRC at different ages face different challenges. Young children face increased vulnerability due to SRC that coincides with periods of brain motor maturation and development.

Clinical outcomes and thermodynamics aspect of direct brain cooling in severe head injury

Background

Brain cooling therapy is one of the subjects of interest, and currently, data on direct brain cooling are lacking. Hence, the objective is to investigate the clinical outcomes and discuss the thermodynamics aspect of direct brain cooling on severely injured brain patients.

Methods

This pilot study recruited the severely injured brain patients who were then randomized to either a direct brain cooling therapy group using a constant cooling temperature system or a control group. All studied patients must be subjected to an emergency neurosurgical procedure of decompressive craniectomy and were monitored with intracranial pressure, brain oxygenation, and temperature. Further, comparison was made with our historical group of patients who had direct brain cooling therapy through the old technique.

Results

The results disclosed the direct brain cooling treated patients through a newer technique obtained a better Extended Glasgow Outcome Score than a control group (P < 001). In addition, there is a significant outcome difference between the combined cooling treated patients (new and old technique) with the control group (P < 0.001). Focal brain oxygenation and temperature are likely factors that correlate with better outcomes.

Conclusion

Direct brain cooling is feasible, safe, and affects the clinical outcomes of the severely traumatized brain, and physics of thermodynamics may play a role in its pathophysiology.

Decompressive Craniectomy vs. Craniotomy Only for Traumatic Brain Injury: A Propensity-Matched Study of Long-Term Outcomes in Neuropsychology

Background

Both decompressive craniectomy (DC) and craniotomy only (CO) are commonly performed to treat patients with traumatic brain injury (TBI) by evacuation of intracranial hemorrhage (ICH) and control intracranial pressure (ICP). The outcomes of these two procedures have been well-studied; however, most research studies have focused on physical functions. The purpose of our study is to assess long-term outcomes in neuropsychology after DC or CO in TBI patients.

Methods

Information was collected from patients with TBI who had undergone DC or CO and were then in the postoperative stable phase (6–24 months after injury). Propensity scoring matched the patients in a 1:1 ratio for demographics, cause of injury, TBI subtype, TBI severity, computed tomography (CT) findings, surgery side, and interval from TBI. We used Wechsler Adult Intelligence Scale-Chinese Revision (WAIS-RC), Wechsler Memory Scale-Chinese Revision (WMS-RC), Physical Self-maintenance Scale (PSMS), Instrumental Activities of Daily Living Scale (IADL), and Glasgow Outcome Scale-Extended (GOSE) to measure the long-term outcomes in TBI patients, especially in neuropsychology.

Results

There were 120 TBI patients included in our study. After matching, 74 patients were paired into the DC group (n = 37) and the CO group (n = 37). There were no differences in the gender (P = 1.000), age at injury (P = 0.268), marital status (P = 0.744), pre-injury employment (P = 0.711), comorbidities (P = 1.000), education level (P = 0.969), cause of injury (P = 0.357), TBI subtype (P = 0.305), Glasgow Coma Scale (GCS) total score (P = 0.193), unconsciousness (P = 0.485), traumatic subarachnoid hemorrhage (tSAH) (P = 0.102), unresponsive pupil (P = 1.000), midline shift (P = 0.409), cisterns compressed or absent (P = 0.485), surgery side (P = 0.795), and interval from TBI (P = 0.840) between the two groups. The CO group was associated with better cognitive function in WAIS-RC OIQ (P = 0.030) and WAIS-RC FIQ (P = 0.021) and better daily function in IADL (P = 0.028) and ADL total (P = 0.030). The DC group also had a lower GOSE (P = 0.004) score compared to the CO group. No difference was observed in WAIS-VIQ (P = 0.062), WMS-RC MQ (P = 0.162), and PSMS (P = 0.319).

Conclusion

In the matched cohort, patients who underwent CO had better long-term outcomes in cognitive and daily function compared with DC. Future randomized control trials are needed for intensive studies on physical and neuropsychological prognosis in TBI patients.

Colony-stimulating factor 1 receptor signaling in the central nervous system and the potential of its pharmacological inhibitors to halt the progression of neurological disorders

Colony Stimulating Factor-1 (CSF-1)/Colony Stimulating Factor-1 Receptor (CSF-1R) signaling axis plays an essential role in the development, maintenance, and proliferation of macrophage lineage cells. Within the central nervous system, CSF-1R signaling primarily maintains microglial homeostasis. Microglia, being the resident macrophage and first responder to any neurological insults, plays critical importance in overall health of the human brain. Aberrant and sustained activation of microglia along with continued proliferation and release of neurotoxic proinflammatory cytokines have been reported in various neurological and neurodegenerative diseases. Therefore, halting the neuroinflammatory pathway via targeting microglial proliferation, which depends on CSF-1R signaling, has emerged as a potential therapeutic target for neurological disorders. However, apart from regulating the microglial function, recently it has been discovered that CSF-1R has much broader role in central nervous system. These findings limit the therapeutic utility of CSF-1R inhibitors but also highlight the need for a complete understanding of CSF-1R function within the central nervous system. Moreover, it has been found that selective inhibitors of CSF-1R may be more efficient in avoiding non-specific targeting and associated side effects. Short-term depletion of microglial population in diseased conditions have also been found to be beneficial; however, the dose and therapeutic window for optimum effects may need to be standardized further.This review summarizes the present understanding of CSF-1R function within the central nervous system. We discuss the CSF-1R signaling in the context of microglia function, crosstalk between microglia and astroglia, and regulation of neuronal cell function. We also discuss a few of the neurological disorders with a focus on the utility of CSF-1R inhibitors as potential therapeutic strategy for halting the progression of neurological diseases.

Survival status and predictors of mortality among traumatic brain injury patients in an Ethiopian hospital: A retrospective cohort study

INTRODUCTION

Traumatic brain injury is a major global public health problem causing substantial mortality among the adult population. Hence, this study aimed to determine the predictors of mortality among adult traumatic brain injury patients in Felegehiwot Comprehensive Specialized Hospital in Northwest Ethiopia during 2020.

METHODS

A retrospective cohort study was conducted at Felegehiwot Comprehensive Specialized Hospital using anonymized patient data obtained from chart review. Descriptive statistics were used to summarise the patient characteristics. The Kaplan-Meier survival curve and log-rank test were used to test for differences in survival status among groups. The Cox proportional hazards regression model was used at the 5% level of significance to determine the net effect of each explanatory variable on time to death.

RESULTS

In total, 338 patients aged ≥15 years and diagnosed with traumatic brain injury were included in the analysis. Among these patients, 103 (30.45%) died, giving a crude death rate of 25.53 per 1000 (95% CI: 21.05-30.98) person-days of follow-up. The overall median survival time was 44 days. The independent predictors of mortality after diagnosis of traumatic brain injury were admission Glasgow coma scale score ≤ 8 (adjusted hazard ratio (AHR): 4.85; 95% confidence interval (CI): 1.73-13.62), bilateral non-reactive pupils at admission (AHR: 2.00 (95% CI: 1.10-3.71), elevated systolic blood pressure at admission (AHR: 0.31; 95% CI:0.11-0.86), elevated diastolic blood pressure at admission (AHR: 3.54; 95% CI: 1.33-9.43), and haematoma evacuation (AHR: 0.42; 95% CI: 0.16-0.90).

DISCUSSION

The Survival status of traumatic brain injury patients was relatively low in this study. Glasgow coma scale score, bilateral non-reactive pupils, and elevated blood pressure were significant predictors of mortality. Further prospective follow-up studies that include residence and occupation are recommended.

Long term neuroprotective effects of acute single dose MK-801treatment against traumatic brain injury in immature rats

Because brain development continues during adolescence, childhood trauma is a major health problem in pediatric ages. It is known traumatic brain injury (TBI) results in damage in hippocampal and cortical areas of the brain and impairs cognitive functions. The study aims to investigate the long-term effects of MK-801 (dizocilpine), an N-methyl d-aspartate (NMDA) receptor antagonist, on hippocampal damage, locomotor activity, and cognitive functions following TBI in immature rats. MK-801 (1 mg/kg) was injected intraperitoneally immediately after TBI. Thirty-seven litters were randomly allocated into three groups at 7 days (P7) of postnatal age: a control group, a trauma group, and an MK-801 treatment group. The control group received no treatment; the trauma group received saline as vehicle control for the MK-801 group and the MK-801 group received a single dose of 1 mg/kg MK-801 immediately after TBI. Hippocampal damage was examined by Hematoxylin-Eosin staining. Brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), NMDA-R, and glial fibrillar acidic protein (GFAP) immunohistochemistry and, BDNF, NGF, and NMDA-R ELISA protein levels were evaluated 125 days after trauma. Histopathological and immunohistochemical evaluations showed that treatment with MK-801 significantly ameliorated the trauma-induced hippocampal neuron loss and increased BDNF, NGF, NMDA-R, GFAP expressions in CA1, CA3, and DG hippocampal regions. Additionally, treatment with MK-801 decreased anxiety and increased hippocampus-dependent memory of animals subjected to brain injury after TBI. These results show that acute treatment of MK-801 has a neuroprotective role against trauma-induced hippocampal neuron loss and associated cognitive impairment in rats.

Early IGF-1 Gene Therapy Prevented Oxidative Stress and Cognitive Deficits Induced by Traumatic Brain Injury

Traumatic Brain Injury (TBI) remains a leading cause of morbidity and mortality in adults under 40 years old. Once primary injury occurs after TBI, neuroinflammation and oxidative stress (OS) are triggered, contributing to the development of many TBI-induced neurological deficits, and reducing the probability of critical trauma patients´ survival. Regardless the research investment on the development of anti-inflammatory and neuroprotective treatments, most pre-clinical studies have failed to report significant effects, probably because of the limited blood brain barrier permeability of no-steroidal or steroidal anti-inflammatory drugs. Lately, neurotrophic factors, such as the insulin-like growth factor 1 (IGF-1), are considered attractive therapeutic alternatives for diverse neurological pathologies, as they are neuromodulators linked to neuroprotection and anti-inflammatory effects. Considering this background, the aim of the present investigation is to test early IGF-1 gene therapy in both OS markers and cognitive deficits induced by TBI. Male Wistar rats were injected via Cisterna Magna with recombinant adenoviral vectors containing the IGF-1 gene cDNA 15 min post-TBI. Animals were sacrificed after 60 min, 24 h or 7 days to study the advanced oxidation protein products (AOPP) and malondialdehyde (MDA) levels, to recognize the protein oxidation damage and lipid peroxidation respectively, in the TBI neighboring brain areas. Cognitive deficits were assessed by evaluating working memory 7 days after TBI. The results reported significant increases of AOPP and MDA levels at 60 min, 24 h, and 7 days after TBI in the prefrontal cortex, motor cortex and hippocampus. In addition, at day 7, TBI also reduced working memory performance. Interestingly, AOPP, and MDA levels in the studied brain areas were significantly reduced after IGF-1 gene therapy that in turn prevented cognitive deficits, restoring TBI-animals working memory performance to similar values regarding control. In conclusion, early IGF-1 gene therapy could be considered a novel therapeutic approach to targeting neuroinflammation as well as to preventing some behavioral deficits related to TBI.

A Clinical Test for a Newly Developed Direct Brain Cooling System for the Injured Brain and Pattern of Cortical Brainwaves in Cooling, Noncooling, and Dead Brain

To ensure the direct delivery of therapeutic hypothermia at a selected constant temperature to the injured brain, a newly innovated direct brain cooling system was constructed. The practicality, effectiveness, and safety of this system were clinically tested in our initial series of 14 patients with severe head injuries. The patients were randomized into two groups: direct brain cooling at 32°C and the control group. All of them received intracranial pressure (ICP), focal brain oxygenation, brain temperature, and direct cortical brainwave monitoring. The direct brain cooling group did better in the Extended Glasgow Outcome Scale at the time of discharge and at 6 months after trauma. This could be owing to a trend in the monitored parameters; reduction in ICP, increment in cerebral perfusion pressure, optimal brain redox regulation, near-normal brain temperature, and lessening of epileptic-like brainwave activities are likely the reasons for better outcomes in the cooling group. Finally, this study depicts interesting cortical brainwaves during a transition time from being alive to dead. It is believed that the demonstrated cortical brainwaves follow the principles of quantum physics.

Use of Machine Learning to Re-Assess Patterns of Multivariate Functional Recovery after Fluid Percussion Injury: Operation Brain Trauma Therapy

Traumatic brain injury (TBI) is a leading cause of death and disability. Yet, despite immense research efforts, treatment options remain elusive. Translational failures in TBI are often attributed to the heterogeneity of the TBI population and limited methods to capture these individual variabilities. Advances in machine learning (ML) have the potential to further personalized treatment strategies and better inform translational research. However, the use of ML has yet to be widely assessed in pre-clinical neurotrauma research, where data are strictly limited in subject number. To better establish ML's feasibility, we utilized the fluid percussion injury (FPI) portion of the rich, rat data set collected by Operation Brain Trauma Therapy (OBTT), which tested multiple pharmacological treatments. Previous work has provided confidence that both unsupervised and supervised ML techniques can uncover useful insights from this OBTT pre-clinical research data set. As a proof-of-concept, we aimed to better evaluate the multi-variate recovery profiles afforded by the administration of nine different experimental therapies. We assessed supervised pairwise classifiers trained on a pre-processed data set that incorporated metrics from four feature groups to determine their ability to correctly identify specific drug treatments. In all but one of the possible pairwise combinations of minocycline, levetiracetam, erythropoietin, nicotinamide, and amantadine, the baseline was outperformed by one or more supervised classifiers, the exception being nicotinamide versus amantadine. Further, when the same methods were employed to assess different doses of the same treatment, the ML classifiers had greater difficulty in understanding which treatment each sample received. Our data serve as a critical first step toward identifying optimal treatments for specific subgroups of samples that are dependent on factors such as types and severity of traumatic injuries, as well as informing the prediction of therapeutic combinations that may lead to greater treatment effects than individual therapies.

In vivo Two-Photon Imaging Reveals Acute Cerebral Vascular Spasm and Microthrombosis After Mild Traumatic Brain Injury in Mice

Mild traumatic brain injury (mTBI), or concussion, is reported to interfere with cerebral blood flow and microcirculation in patients, but our current understanding is quite limited and the results are often controversial. Here we used longitudinal in vivo two-photon imaging to investigate dynamic changes in cerebral vessels and velocities of red blood cells (RBC) following mTBI. Closed-head mTBI induced using a controlled cortical impact device resulted in a significant reduction of dwell time in a Rotarod test but no significant change in water maze test. Cerebral blood vessels were repeatedly imaged through a thinned skull window at baseline, 0.5, 1, 6 h, and 1 day following mTBI. In both arterioles and capillaries, their diameters and RBC velocities were significantly decreased at 0.5, 1, and 6 h after injury, and recovered in 1 day post-mTBI. In contrast, decreases in the diameter and RBC velocity of venules occurred only in 0.5–1 h after mTBI. We also observed formation and clearance of transient microthrombi in capillaries within 1 h post-mTBI. We concluded that in vivo two-photon imaging is useful for studying earlier alteration of vascular dynamics after mTBI and that mTBI induced reduction of cerebral blood flow, vasospasm, and formation of microthrombi in the acute stage following injury. These changes may contribute to early brain functional deficits of mTBI.

Can Mesenchymal Stem Cells Act Multipotential in Traumatic Brain Injury?

Traumatic brain injury (TBI), a leading cause of morbidity and mortality throughout the world, will probably become the third cause of death in the world by the year 2020. Lack of effective treatments approved for TBI is a major health problem. TBI is a heterogeneous disease due to the different mechanisms of injury. Therefore, it requires combination therapies or multipotential therapy that can affect multiple targets. In recent years, mesenchymal stem cells (MSCs) transplantation has considered one of the most promising therapeutic strategies to repair of brain injuries including TBI. In these studies, it has been shown that MSCs can migrate to the site of injury and differentiate into the cells secreting growth factors and anti-inflammatory cytokines. The reduction in brain edema, neuroinflammation, microglia accumulation, apoptosis, ischemia, the improvement of motor and cognitive function, and the enhancement in neurogenesis, angiogenesis, and neural stem cells survival, proliferation, and differentiation have been indicated in these studies. However, translation of MSCs research in TBI into a clinical setting will require additional preclinical trials.

Aberrant ER Stress Induced Neuronal-IFNβ Elicits White Matter Injury Due to Microglial Activation and T-Cell Infiltration after TBI

Persistent endoplasmic reticulum (ER) stress in neurons is associated with activation of inflammatory cells and subsequent neuroinflammation following traumatic brain injury (TBI); however, the underlying mechanism remains elusive. We found that induction of neuronal-ER stress, which was mostly characterized by an increase in phosphorylation of a protein kinase R-like ER kinase (PERK) leads to release of excess interferon (IFN)β due to atypical activation of the neuronal-STING signaling pathway. IFNβ enforced activation and polarization of the primary microglial cells to inflammatory M1 phenotype with the secretion of a proinflammatory chemokine CXCL10 due to activation of STAT1 signaling. The secreted CXCL10, in turn, stimulated the T-cell infiltration by serving as the ligand and chemoattractant for CXCR3⁺ T-helper 1 (Th1) cells. The activation of microglial cells and infiltration of Th1 cells resulted in white matter injury, characterized by impaired myelin basic protein and neurofilament NF200, the reduced thickness of corpus callosum and external capsule, and decline of mature oligodendrocytes and oligodendrocyte precursor cells. Intranasal delivery of CXCL10 siRNA blocked Th1 infiltration but did not fully rescue microglial activation and white matter injury after TBI. However, impeding PERK-phosphorylation through the administration of GSK2656157 abrogated neuronal induction of IFNβ, switched microglial polarization to M2 phenotype, prevented Th1 infiltration, and increased Th2 and Treg levels. These events ultimately attenuated the white matter injury and improved anxiety and depressive-like behavior following TBI.SIGNIFICANCE STATEMENT A recent clinical study showed that human brain trauma patients had enhanced expression of type-1 IFN; suggests that type-1 IFN signaling may potentially influence clinical outcome in TBI patients. However, it was not understood how TBI leads to an increase in IFNβ and whether induction of IFNβ has any influence on neuroinflammation, which is the primary reason for morbidity and mortality in TBI. Our study suggests that induction of PERK phosphorylation, a characteristic feature of ER stress is responsible for an increase in neuronal IFNβ, which, in turn, activates microglial cells and subsequently manifests the infiltration of T cells to induce neuroinflammation and subsequently white matter injury. Blocking PERK phosphorylation using GSK2656157 (or PERK knockdown) the whole cascade of neuroinflammation was attenuated and improved cognitive function after TBI.

Proteasome and Autophagy-Mediated Impairment of Late Long-Term Potentiation (l-LTP) after Traumatic Brain Injury in the Somatosensory Cortex of Mice

Traumatic brain injury (TBI) can lead to impaired cognition and memory consolidation. The acute phase (24–48 h) after TBI is often characterized by neural dysfunction in the vicinity of the lesion, but also in remote areas like the contralateral hemisphere. Protein homeostasis is crucial for synaptic long-term plasticity including the protein degradation systems, proteasome and autophagy. Still, little is known about the acute effects of TBI on synaptic long-term plasticity and protein degradation. Thus, we investigated TBI in a controlled cortical impact (CCI) model in the motor and somatosensory cortex of mice ex vivo-in vitro. Late long-term potentiation (l-LTP) was induced by theta-burst stimulation in acute brain slices after survival times of 1–2 days. Protein levels for the plasticity related protein calcium/calmodulin-dependent protein kinase II (CaMKII) was quantified by Western blots, and the protein degradation activity by enzymatical assays. We observed missing maintenance of l-LTP in the ipsilateral hemisphere, however not in the contralateral hemisphere after TBI. Protein levels of CaMKII were not changed but, interestingly, the protein degradation revealed bidirectional changes with a reduced proteasome activity and an increased autophagic flux in the ipsilateral hemisphere. Finally, LTP recordings in the presence of pharmacologically modified protein degradation systems also led to an impaired synaptic plasticity: bath-applied MG132, a proteasome inhibitor, or rapamycin, an activator of autophagy, both administered during theta burst stimulation, blocked the induction of LTP. These data indicate that alterations in protein degradation pathways likely contribute to cognitive deficits in the acute phase after TBI, which could be interesting for future approaches towards neuroprotective treatments early after traumatic brain injury.

Pioglitazone Therapy and Fractures: Systematic Review and Meta- Analysis

INTRODUCTION

Thiazolidinediones are a group of synthetic medications used in type 2 diabetes treatment. Among available thiazolidinediones, pioglitazone is gaining increased attention due to its lower cardiovascular risk in type 2 diabetes mellitus sufferers and seems a promising future therapy. Accumulating evidence suggests that diabetic patients may exert bone fractures due to such treatments. Simultaneously, the female population is thought to be at greater risk. Still, the safety outcomes of pioglitazone treatment especially in terms of fractures are questionable and need to be clarified.

METHODS

We searched MEDLINE, Scopus, PsyInfo, eLIBRARY.ru electronic databases and clinical trial registries for studies reporting an association between pioglitazone and bone fractures in type 2 diabetes mellitus patients published before Feb 15, 2016. Among 1536 sources that were initially identified, six studies including 3172 patients proved relevant for further analysis.

RESULT

Pooled analysis of the included studies demonstrated that after treatment with pioglitazone patients with type 2 diabetes mellitus had no significant increase in fracture risk [odds ratio (OR): 1.18, 95% confidence interval (CI): 0.82 to 1.71, p=0.38] compared to other antidiabetic drugs or placebo. Additionally, no association was found between the risk of fractures and pioglitazone therapy duration. The gender of the patients involved was not relevant to the risk of fractures, too.

CONCLUSION

Pioglitazone treatment in diabetic patients does not increase the incidence of bone fractures. Moreover, there is no significant association between patients' fractures, their gender and the period of exposure to pioglitazone. Additional longitudinal studies need to be undertaken to obtain more detailed information on bone fragility and pioglitazone therapy.

Changes in Posttraumatic Brain Edema in Craniectomy-Selective Brain Hypothermia Model Are Associated With Modulation of Aquaporin-4 Level

Both hypothermia and decompressive craniectomy have been considered as a treatment for traumatic brain injury. In previous experiments we established a murine model of decompressive craniectomy and we presented attenuated edema formation due to focal brain cooling. Since edema development is regulated via function of water channel proteins, our hypothesis was that the effects of decompressive craniectomy and of hypothermia are associated with a change in aquaporin-4 (AQP4) concentration. Male CD-1 mice were assigned into following groups (n = 5): sham, decompressive craniectomy, trauma, trauma followed by decompressive craniectomy and trauma + decompressive craniectomy followed by focal hypothermia. After 24 h, magnetic resonance imaging with volumetric evaluation of edema and contusion were performed, followed by ELISA analysis of AQP4 concentration in brain homogenates. Additional histopathological analysis of AQP4 immunoreactivity has been performed at more remote time point of 28d. Correlation analysis revealed a relationship between AQP4 level and both volume of edema (r² = 0.45, p < 0.01, ^**) and contusion (r² = 0.41, p < 0.01, ^**) 24 h after injury. Aggregated analysis of AQP4 level (mean ± SEM) presented increased AQP4 concentration in animals subjected to trauma and decompressive craniectomy (52.1 ± 5.2 pg/mL, p = 0.01; ^*), but not to trauma, decompressive craniectomy and hypothermia (45.3 ± 3.6 pg/mL, p > 0.05; ns) as compared with animals subjected to decompressive craniectomy only (32.8 ± 2.4 pg/mL). However, semiquantitative histopathological analysis at remote time point revealed no significant difference in AQP4 immunoreactivity across the experimental groups. This suggests that AQP4 is involved in early stages of brain edema formation after surgical decompression. The protective effect of selective brain cooling may be related to change in AQP4 response after decompressive craniectomy. The therapeutic potential of this interaction should be further explored.

On the Viability and Potential Value of Stem Cells for Repair and Treatment of Central Neurotrauma: Overview and Speculations

Central neurotrauma, such as spinal cord injury or traumatic brain injury, can damage critical axonal pathways and neurons and lead to partial to complete loss of neural function that is difficult to address in the mature central nervous system. Improvement and innovation in the development, manufacture, and delivery of stem-cell based therapies, as well as the continued exploration of newer forms of stem cells, have allowed the professional and public spheres to resolve technical and ethical questions that previously hindered stem cell research for central nervous system injury. Recent in vitro and in vivo models have demonstrated the potential that reprogrammed autologous stem cells, in particular, have to restore functionality and induce regeneration-while potentially mitigating technical issues of immunogenicity, rejection, and ethical issues of embryonic derivation. These newer stem-cell based approaches are not, however, without concerns and problems of safety, efficacy, use and distribution. This review is an assessment of the current state of the science, the potential solutions that have been and are currently being explored, and the problems and questions that arise from what appears to be a promising way forward (i.e., autologous stem cell-based therapies)-for the purpose of advancing the research for much-needed therapeutic interventions for central neurotrauma.

Can the health related quality of life measure QOLIBRI- overall scale (OS) be of use after stroke? A validation study

BACKGROUND

Brief measures of health-related quality of life (HRQOL) that assess both patient-reported functioning and well-being after stroke are scarce. The objective of this study was to examine reliability and validity of one of these measures, the patient-reported Quality of Life after Brain Injury-Overall Scale (QOLIBRI-OS), in patients after stroke.

METHODS

Stroke survivors were examined prospectively using survey methods. Core survey data (n = 125) and retest data (n = 36) were obtained at 3 and 12 months, respectively. Item properties (distribution, floor and ceiling effects), psychometric properties (reliability and model fit), and validity (correlations with established measures of anxiety, depression and HRQOL) of the QOLIBRI-OS were examined.

RESULTS

Missing responses on the questionnaire were low (0.5%). All items were positively skewed. No floor effects were present, whereas five out of six items showed ceiling effects. The summary QOLIBRI-OS score exhibited no floor or ceiling effects, and had excellent internal consistency (Cronbach's α =0.93). All item-total correlations were high (0.73-0.88). The test-retest reliability of single items varied from 0.74 to 0.91 and was 0.93 for the overall score. The confirmatory factor analysis yielded an excellent fit for a five-item version and provided tentative support for the original six-item version. The convergent validity correlations were in the hypothesized directions, thus supporting the construct validity.

CONCLUSIONS

The brief QOLIBRI-OS is a valid and reliable brief health-related outcome measure that is appropriate for screening HRQOL in patients after stroke.

Biofluid biomarkers of traumatic brain injury

PRIMARY OBJECTIVE

The purpose of this paper is to review the clinical and research utility and applications of blood, cerebrospinal fluid (CSF), and cerebral microdialysis biomarkers in traumatic brain injury (TBI).

RESEARCH DESIGN

Not applicable.

METHODS AND PROCEDURES

A selective review was performed on these biofluid biomarkers in TBI.

MAIN OUTCOME AND RESULTS

Neurofilament heavy chain protein (NF-H), glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCHL1), neuron-specific enolase (NSE), myelin basic protein (MBP), tau, and s100β blood biomarkers are elevated during the acute phase of severe head trauma but have key limitations in their research and clinical applications to mild TBI (mTBI). CSF biomarkers currently provide the best reflection of the central nervous system (CNS) pathobiological processes in TBI. Both animal and human studies of TBI have demonstrated the importance of serial sampling of biofluids and suggest that CSF biomarkers may be better equipped to characterize both TBI severity and temporal profiles.

CONCLUSIONS

The identification of biofluid biomarkers could play a vital role in identifying, diagnosing, and treating the underlying individual pathobiological changes of TBI. CNS-derived exosomes analyzed by ultra-high sensitivity detection methods have the potential to identify blood biomarkers for the range of TBI severity and time course.

Endogenous Sex Steroids Dampen Neuroinflammation and Improve Outcome of Traumatic Brain Injury in Mice

The role of biological sex in short-term and long-term outcome after traumatic brain injury (TBI) remains controversial. The observation that exogenous female sex steroids (progesterone and estrogen) reduce brain injury coupled with a small number of clinical studies showing smaller injury in women suggest that sex steroids may play a role in outcome from TBI. We used the controlled cortical impact (CCI) model of TBI in mice to test the hypothesis that after CCI, female mice would demonstrate less injury than male mice, related to the protective role of endogenous steroids. Indeed, adult females exhibit histological protection (3.7 ± 0.5 mm³) compared to adult male mice (6.8 ± 0.6 mm³), and females that lacked sex steroids (ovex) showed increased injury compared to intact females. Consistent with histology, sensorimotor deficits measured as reduced contralateral limb use were most pronounced in male mice (31.9 ± 6.9% reduced limb use) compared to a 12.7 ± 3.8% reduction in female mice. Ovex mice exhibited behavioral deficits similar to males (31.5 ± 3.9% reduced limb use). Ovex females demonstrated increased microglial activation relative to intact females in both the peri-injury cortex and the reticular thalamic nucleus. Ovex females also demonstrated increased astrogliosis in comparison to both females and males in the peri-injury cortex. These data indicate that female sex steroids reduce brain sensitivity to TBI and that reduced acute neuroinflammation may contribute to the relative protection observed in females.

Trovafloxacin attenuates neuroinflammation and improves outcome after traumatic brain injury in mice

Background

Trovafloxacin is a broad-spectrum antibiotic, recently identified as an inhibitor of pannexin-1 (Panx1) channels. Panx1 channels are important conduits for the adenosine triphosphate (ATP) release from live and dying cells that enhances the inflammatory response of immune cells. Elevated extracellular levels ATP released upon injury activate purinergic pathways in inflammatory cells that promote migration, proliferation, phagocytosis, and apoptotic signals. Here, we tested whether trovafloxacin administration attenuates the neuroinflammatory response and improves outcomes after brain trauma.

Methods

The murine controlled cortical impact (CCI) model was used to determine whether in vivo delivery of trovafloxacin has anti-inflammatory and neuroprotective actions after brain trauma. Locomotor deficit was assessed using the rotarod test. Levels of tissue damage markers and inflammation were measured using western blot, qPCR, and immunofluorescence. In vitro assays were used to evaluate whether trovafloxacin blocks ATP release and cell migration in a chemotactic-stimulated microglia cell line.

Results

Trovafloxacin treatment of CCI-injured mice significantly reduced tissue damage markers and improved locomotor deficits. In addition, trovafloxacin treatment significantly reduced mRNA levels of several pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), which correlates with an overall reduction in the accumulation of inflammatory cell types (neutrophils, microglia/macrophages, and astroglia) at the injury zone. To determine whether trovafloxacin exerted these effects by direct action on immune cells, we evaluated its effect on ATP release and cell migration using a chemotactic-stimulated microglial cell line. We found that trovafloxacin significantly inhibited both ATP release and migration of these cells.

Conclusion

Our results show that trovafloxacin administration has pronounced anti-inflammatory and neuroprotective effects following brain injury. These findings lay the foundation for future studies to directly test a role for Panx1 channels in pathological inflammation following brain trauma.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1069-9) contains supplementary material, which is available to authorized users.

Epileptogenesis following experimentally induced traumatic brain injury - a systematic review

Traumatic brain injury (TBI) is a complex neurotrauma in civilian life and the battlefield with a broad spectrum of symptoms, long-term neuropsychological disability, as well as mortality worldwide. Posttraumatic epilepsy (PTE) is a common outcome of TBI with unknown mechanisms, followed by posttraumatic epileptogenesis. There are numerous rodent models of TBI available with varying pathomechanisms of head injury similar to human TBI, but there is no evidence for an adequate TBI model that can properly mimic all aspects of clinical TBI and the first successive spontaneous focal seizures follow a single episode of neurotrauma with respect to epileptogenesis. This review aims to provide current information regarding the various experimental animal models of TBI relevant to clinical TBI. Mossy fiber sprouting, loss of dentate hilar neurons along with recurrent seizures, and epileptic discharge similar to human PTE have been studied in fluid percussion injury, weight-drop injury, and cortical impact models, but further refinement of animal models and functional test is warranted to better understand the underlying pathophysiology of posttraumatic epileptogenesis. A multifaceted research approach in TBI model may lead to exploration of the potential treatment measures, which are a major challenge to the research community and drug developers. With respect to clinical setting, proper patient data collection, improved clinical trials with advancement in drug delivery strategies, blood-brain barrier permeability, and proper monitoring of level and effects of target drug are also important.

Brain injury and neural stem cells

Many therapies with potential for treatment of brain injury have been investigated. Few types of cells have spurred as much interest and excitement as stem cells over the past few decades. The multipotentiality and self-renewing characteristics of stem cells confer upon them the capability to regenerate lost tissue in ischemic or degenerative conditions as well as trauma. While stem cells have not yet proven to be clinically effective in many such conditions as was once hoped, they have demonstrated some effects that could be manipulated for clinical benefit. The various types of stem cells have similar characteristics, and largely differ in terms of origin; those that have differentiated to some extent may exhibit limited capability in differentiation potential. Stem cells can aid in decreasing lesion size and improving function following brain injury.

Investigating structural and perfusion deficits due to repeated head trauma in active professional fighters

Repeated head trauma experienced by active professional fighters results in various structural, functional and perfusion damage. However, whether there are common regions of structural and perfusion damage due to fighting and whether these structural and perfusion differences are associated with neuropsychological measurements in active professional fighters is still unknown. To that end, T1-weighted and pseudocontinuous arterial spin labeling MRI on a group of healthy controls and active professional fighters were acquired. Voxelwise group comparisons, in a univariate and multivariate sense, were performed to investigate differences in gray and white matter density (GMD, WMD) and cerebral blood flow (CBF) between the two groups. A significantly positive association between global GMD and WMD was obtained with psychomotor speed and reaction time, respectively, in our cohort of active professional fighters. In addition, regional WMD deficit was observed in a cluster encompassing bilateral pons, hippocampus, and thalamus in fighters (0.49 ± 0.04 arbitrary units (a.u.)) as compared to controls (0.51 ± 0.05a.u.). WMD in the cluster of active fighters was also significantly associated with reaction time. Significantly lower CBF was observed in right inferior temporal lobe with both partial volume corrected (46.9 ± 14.93 ml/100 g/min) and non-partial volume corrected CBF maps (25.91 ± 7.99 ml/100 g/min) in professional fighters, as compared to controls (65.45 ± 22.24 ml/100 g/min and 35.22 ± 12.18 ml/100 g/min respectively). A paradoxical increase in CBF accompanying right cerebellum and fusiform gyrus in the active professional fighters (29.52 ± 13.03 ml/100 g/min) as compared to controls (19.43 ± 12.56 ml/100 g/min) was observed with non-partial volume corrected CBF maps. Multivariate analysis with both structural and perfusion measurements found the same clusters as univariate analysis in addition to a cluster in right precuneus. Both partial volume corrected and non-partial volume corrected CBF of the cluster in the thalamus had a significantly positive association with the number of fights. In addition, GMD of the cluster in right precuneus was significantly associated with psychomotor speed in our cohort of active professional fighters. Our results suggest a heterogeneous pattern of structural and CBF deficits due to repeated head trauma in active professional fighters. This finding indicates that investigating both structural and CBF changes in the same set of participants may help to understand the pathophysiology and progression of cognitive decline due to repeated head trauma.

•

Repetitive head trauma revealed no global structural or global perfusion deficits.

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Cluster of significantly lower WMD was associated with reaction time in fighters.

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Fighters had lower CBF in right inferior temporal lobe.

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Multivariate analysis revealed a cluster associated with number of fights.

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Combined analysis of structural and perfusion measurements is recommended.

Neuropsychology of traumatic brain injury: An expert overview

Traumatic brain injury (TBI) is a serious healthcare problem, and this report is a selective review of recent findings on the epidemiology, pathophysiology and neuropsychological impairments following TBI. Patients who survive moderate-to-severe TBI frequently suffer from a wide range of cognitive deficits and behavioral changes due to diffuse axonal injury. These deficits include slowed information-processing and impaired long-term memory, attention, working memory, executive function, social cognition and self-awareness. Mental fatigue is frequently also associated and can exacerbate the consequences of neuropsychological deficits. Personality and behavioral changes can include combinations of impulsivity and apathy. Even mild TBI raises specific problems: while most patients recover within a few weeks or months, a minority of patients may suffer from long-lasting symptoms (post-concussion syndrome). The pathophysiology of such persistent problems remains a subject of debate, but seems to be due to both injury-related and non-injury-related factors.

Activation of PERK Elicits Memory Impairment through Inactivation of CREB and Downregulation of PSD95 After Traumatic Brain Injury

The PKR-like ER kinase (PERK), a transmembrane protein, resides in the endoplasmic reticulum (ER). Its activation serves as a key sensor of ER stress, which has been implicated in traumatic brain injury (TBI). The loss of memory is one of the most common symptoms after TBI, but the precise role of PERK activation in memory impairment after TBI has not been well elucidated. Here, we have shown that blocking the activation of PERK using GSK2656157 prevents the loss of dendritic spines and rescues memory deficits after TBI. To elucidate the molecular mechanism, we found that activated PERK phosphorylates CAMP response element binding protein (CREB) and PSD95 directly at the S129 and T19 residues, respectively. Phosphorylation of CREB protein prevents its interaction with a coactivator, CREB-binding protein, and subsequently reduces the BDNF level after TBI. Conversely, phosphorylation of PSD95 leads to its downregulation in pericontusional cortex after TBI in male mice. Treatment with either GSK2656157 or overexpression of a kinase-dead mutant of PERK (PERK-K618A) rescues BDNF and PSD95 levels in the pericontusional cortex by reducing phosphorylation of CREB and PSD95 proteins after TBI. Similarly, administration of either GSK2656157 or overexpression of PERK-K618A in primary neurons rescues the loss of dendritic outgrowth and number of synapses after treatment with a PERK activator, tunicamycin. Therefore, our study suggests that inhibition of PERK phosphorylation could be a potential therapeutic target to restore memory deficits after TBI.SIGNIFICANCE STATEMENT Traumatic brain injury (TBI) is the leading cause of death and disability around the world and affects 1.7 million Americans each year. Here, we have shown that TBI-activated PKR-like ER kinase (PERK) is responsible for memory deficiency, which is the most common problem in TBI patients. A majority of PERK's biological activities have been attributed to its function as an eIF2α kinase. However, our study suggests that activated PERK mediates its function via increasing phosphorylation of CAMP response element binding protein (CREB) and PSD95 after TBI. Blocking PERK phosphorylation rescues spine loss and memory deficits independently of phosphorylation of eIF2α. Therefore, our study suggests that CREB and PSD95 are novel substrates of PERK, so inhibition of PERK phosphorylation using GSK2656157 would be beneficial against memory impairment after TBI.

Quercetin attenuates neuronal autophagy and apoptosis in rat traumatic brain injury model via activation of PI3K/Akt signaling pathway

OBJECTIVE

Neuronal autophagy and apoptosis play an irreplaceable role in brain injury pathogenesis and may represent a hopeful target for treatment. Previous studies have demonstrated that administration of quercetin-attenuated brain damage in a variety of brain injury models including traumatic brain injury (TBI). However, whether PI3K/Akt signaling pathway mediates the neuroprotection of quercetin following TBI is not well clarified. We sought to propose a hypothesis that quercetin could attenuate neuronal autophagy and apoptosis via enhancing PI3K/Akt signaling.

METHODS

All rats were randomly arranged into four groups as follows: sham group (n = 25), TBI group (n = 25), TBI + quercetin group (n = 25), TBI + quercetin + LY294002 group (n = 25). Quercetin (Sigma, USA, dissolved in 0.9% saline solution) was administered intraperitoneally at a dose of 50 mg/kg at 30 min, 12 h, and 24 h after TBI. The neurological impairment and spatial cognitive function was assessed by the neurologic severity score and Morris water maze, respectively. Immunohistochemistry staining and western blotting was used to evaluate the expression of LC3, p-Akt, caspase-3, Bcl-2, and Bax.

RESULTS

Quercetin treatment significantly attenuated TBI-induced neurological impairment (1-3 days, p < 0.05) and improved cognitive function (5-8 days, p < 0.05). Double immunolabeling demonstrated that quercetin significantly reduced the LC3-positive cells co-labeled with NeuN, whereas significantly enhanced p-Akt-positive cells co-labeled with NeuN. Furthermore, quercetin treatment reduced the expression of LC3、caspase-3 and Bax levels induced following TBI (p < 0.05), and increased the expression of p-Akt and Bcl-2 at 48 h (p < 0.05).

CONCLUSION

In conclusion, our observations indicate that post-injury treatment with quercetin could inhibit neuronal autophagy and apoptosis in the hippocampus in a rat model of TBI. The neuroprotective effects of quercetin may be related to modulation of PI3K/Akt signaling pathway.

Tropomyosins in the healthy and diseased nervous system

Regulation of the actin cytoskeleton is dependent on a plethora of actin-associated proteins in all eukaryotic cells. The family of tropomyosins plays a key role in controlling the function of several of these actin-associated proteins and their access to actin filaments. In order to understand the regulation of the actin cytoskeleton in highly dynamic subcellular compartments of neurons such as growth cones of developing neurons and the synaptic compartment of mature neurons, it is pivotal to decipher the functional role of tropomyosins in the nervous system. In this review, we will discuss the current understanding and recent findings on the regulation of the actin cytoskeleton by tropomyosins and potential implication that this has for the dysregulation of the actin cytoskeleton in neurological diseases.

Bone Fracture Enhances Trauma Brain Injury

Traumatic brain injury (TBI) is one of the leading causes of mortality and morbidity in young individuals worldwide. However, the understanding of TBI at secondary phase remained obscure, and more knowledge of the pathophysiology of TBI is necessary. In this study, we examined the influence of bone fracture (BF) on TBI and investigated whether blocking high mobility group 1 (HMGB1) protein, an inflammatory mediator, could be effective to alleviate TBI. We found neurological severity was significantly increased by BF at 4 days post-TBI with longer removal time of adhesive tape and higher percentage of left turn in the corner test compared to TBI treatment alone. Additionally, higher brain lesion volume and severer brain oedema in TBI + BF mice supports the negative effect of BF on TBI. HMGB1 level was significantly stimulated by BF, suggesting the important role of HMGB1 in the development of secondary TBI. Notably, ablation of HMGB1 significantly reduced this negative influence of BF on TBI. These results suggest that HMGB1 can be massively induced by the systemic immune activation triggered by BF, which in turn aggravates inflammation. Blocking HMGB1 reduced the inflammatory effect of BF and therefore helps lessen the severity of secondary TBI. In conclusion, these results provided the evidence that anti-HMGB1 may be an effective and feasible method to alleviate TBI.

Astrocytic Ephrin-B1 Regulates Synapse Remodeling Following Traumatic Brain Injury

Traumatic brain injury (TBI) can result in tissue alterations distant from the site of the initial injury, which can trigger pathological changes within hippocampal circuits and are thought to contribute to long-term cognitive and neuropsychological impairments. However, our understanding of secondary injury mechanisms is limited. Astrocytes play an important role in brain repair after injury and astrocyte-mediated mechanisms that are implicated in synapse development are likely important in injury-induced synapse remodeling. Our studies suggest a new role of ephrin-B1, which is known to regulate synapse development in neurons, in astrocyte-mediated synapse remodeling following TBI. Indeed, we observed a transient upregulation of ephrin-B1 immunoreactivity in hippocampal astrocytes following moderate controlled cortical impact model of TBI. The upregulation of ephrin-B1 levels in hippocampal astrocytes coincided with a decline in the number of vGlut1-positive glutamatergic input to CA1 neurons at 3 days post injury even in the absence of hippocampal neuron loss. In contrast, tamoxifen-induced ablation of ephrin-B1 from adult astrocytes in ephrin-B1^loxP/yERT2-Cre^GFAP mice accelerated the recovery of vGlut1-positive glutamatergic input to CA1 neurons after TBI. Finally, our studies suggest that astrocytic ephrin-B1 may play an active role in injury-induced synapse remodeling through the activation of STAT3-mediated signaling in astrocytes. TBI-induced upregulation of STAT3 phosphorylation within the hippocampus was suppressed by astrocyte-specific ablation of ephrin-B1 in vivo, whereas the activation of ephrin-B1 in astrocytes triggered an increase in STAT3 phosphorylation in vitro. Thus, regulation of ephrin-B1 signaling in astrocytes may provide new therapeutic opportunities to aid functional recovery after TBI.

Magnetic Resonance Imaging in Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability in the USA. Common causes of TBI include falls, violence, injuries from wars, and vehicular and sporting accidents. The initial direct mechanical damage in TBI is followed by progressive secondary injuries such as brain swelling, perturbed cerebral blood flow (CBF), abnormal cerebrovascular reactivity (CR), metabolic dysfunction, blood-brain-barrier disruption, inflammation, oxidative stress, and excitotoxicity, among others. Magnetic resonance imaging (MRI) offers the means to noninvasively probe many of these secondary injuries. MRI has been used to image anatomical, physiological, and functional changes associated with TBI in a longitudinal manner. This chapter describes controlled cortical impact (CCI) TBI surgical procedures, a few common MRI protocols used in TBI imaging, and, finally, image analysis pertaining to experimental TBI imaging in rats.

Traumatic brain injury, driver aggression and motor vehicle collisions in Canadian adults

OBJECTIVE

This study examines the associations between lifetime traumatic brain injury (TBI), driver aggression, and motor vehicle collisions among a population sample of adults who reside in the province of Ontario, Canada.

METHOD

A cross-sectional sample of 3993 Ontario adults, aged 18-97 were surveyed by telephone in 2011 and 2012 as part of Center for Addiction and Mental Health's ongoing representative survey of adult mental health and substance use in Canada. TBI was defined as trauma to the head that resulted in loss of consciousness for at least five minutes or overnight hospitalization.

RESULTS

An estimated 91% (95% CI: 90.0, 91.9) of individuals in this sample held a valid Ontario driver's license at the time of testing. Among those, 16.7% reported a history of lifetime TBI and 83.3% reported no TBI. The prevalence of TBI was higher among men than women. Relative to licensed adults without TBI, adults with a history of TBI had significantly higher odds of engaging in serious driver aggression in the past 12 months, such as making threats to hurt another driver, passenger or their vehicle (AOR=4.39). These individuals also reported significantly higher odds (AOR=1.74) of being involved in a motor vehicle collision that resulted in hurting themselves, their passenger(s) or their vehicle.

CONCLUSION

This is the first population-based study to demonstrate a relationship between a history of TBI and higher rates of serious driver aggression and collision involvement. Given the large proportion of adult drivers with a history of TBI, these individuals may account for a disproportion burden of all traffic safety problems. Whether the increased road safety risk of adults with a history of TBI is reflective of neurocognitive deficits or is merely evidence of a cluster of unsafe activities produced by a higher risk lifestyles requires further research attention.

Normobaric oxygen worsens outcome after a moderate traumatic brain injury

Traumatic brain injury (TBI) is a multifaceted injury and a leading cause of death in children, young adults, and increasingly in Veterans. However, there are no neuroprotective agents clinically available to counteract damage or promote repair after brain trauma. This study investigated the neuroprotective effects of normobaric oxygen (NBO) after a controlled cortical impact in rats. The central hypothesis was that NBO treatment would reduce lesion volume and functional deficits compared with air-treated animals after TBI by increasing brain oxygenation thereby minimizing ischemic injury. In a randomized double-blinded design, animals received either NBO (n = 8) or normal air (n = 8) after TBI. Magnetic resonance imaging (MRI) was performed 0 to 3 hours, and 1, 2, 7, and 14 days after an impact to the primary forelimb somatosensory cortex. Behavioral assessments were performed before injury induction and before MRI scans on days 2, 7, and 14. Nissl staining was performed on day 14 to corroborate the lesion volume detected from MRI. Contrary to our hypothesis, we found that NBO treatment increased lesion volume in a rat model of moderate TBI and had no positive effect on behavioral measures. Our results do not promote the acute use of NBO in patients with moderate TBI.