Pharmacology of traumatic brain injury: where is the "golden bullet"?

Antisecretory Factor 16 (AF16): A Promising Avenue for the Treatment of Traumatic Brain Injury-An In Vitro Model Approach

Traumatic brain injury (TBI) is caused by an external mechanical force to the head, resulting in abnormal brain functioning and clinical manifestations. Antisecretory factor (AF16) is a potential therapeutic agent for TBI treatment due to its ability to inhibit fluid secretion and decrease inflammation, intracranial pressure, and interstitial fluid build-up, key hallmarks presented in TBI. Here, we investigated the effect of AF16 in an in vitro model of neuronal injury, as well as its impact on key components of the autophagy pathway and mitochondrial dynamics. N2Awt cells were treated with AF16, injured using a scratch assay, and analysed using confocal microscopy, correlative light and electron microscopy (CLEM), flow cytometry, and western blotting. Our results reveal that AF16 enhances autophagy activity, regulates mitochondrial dynamics, and provides protection as early as 6 h post-injury. Fluorescently labelled AF16 was observed to localise to lysosomes and the autophagy compartment, suggesting a role for autophagy and mitochondrial quality control in conferring AF16-associated neuronal protection. This study concludes that AF16 has potential as a therapeutic agent for TBI treatment through is regulation of autophagy and mitochondrial dynamics.

Characterization of an Advanced Blast Simulator for Investigation of Large Scale Blast Traumatic Brain Injury Studies

Blast traumatic brain injury (bTBI) is a prominent military health concern. The pervasiveness and long-term impacts of this injury highlight the need for investigation of the physiological outcomes of bTBI. Preclinical models allow for the evaluation of behavioral and neuropathological sequelae associated with bTBI. Studies have implemented rodent models to investigate bTBI due to the relative small size and low cost; however, a large animal model with similar neuroanatomical structure to humans is essential for clinical translation. Small blast simulators are used to induce bTBI in rodents, but a large animal model demands a larger device. This study describes a large advanced blast simulator (ABS4) that is a gas-detonation-driven system consisting of 5 sections totaling 40 ft in length with a cross-section of 4 × 4 ft at the test section. It is highly suitable for large animals and human surrogate investigations. This work characterized the ABS4 in preparation of large-scale bTBI testing. An array of tests were conducted with target overpressures in the test section ranging from 10 to 50 psi, and the pressure-time profiles clearly illustrate the essential characteristics of a free-field blast wave, specifically a sharp peak pressure and a defined negative phase. Multiple blast tests conducted at the same target pressure produced very similar pressure profiles, exhibiting the reproducibility of the ABS4 system. With its extensive range of pressures and substantial size, the ABS4 will permit military-relevant translational blast testing.

Evidence-Based Review of Randomized Controlled Trials of Interventions for the Management of Behavioral Issues in Individuals With Moderate to Severe Traumatic Brain Injury

OBJECTIVE

To present an evidence-based review of randomized controlled trials (RCTs) evaluating interventions for the management of behavioral issues post moderate to severe traumatic brain injury (MSTBI), as part of an extensive database that has been conceptualized as a living systematic review.

METHODS

Systematic searches were conducted in MEDLINE, PubMed, Scopus, CINAHL, EMBASE and PsycINFO, up to and including December 2022, for articles published in the English language, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality of RCT was assessed using the Physiotherapy Evidence Database (PEDro) scale, and level of evidence was assigned using a modified Sackett scale.

RESULTS

Forty-six RCTs examining interventions and outcome measures related to behavioral issues post-MSTBI were included. These studies collectively enrolled 3,267 participants. The majority of RCTs were conducted in the United States (n = 27; 58.7%) and 28 (60.9%) were conducted after 2010. Of these, 27 RCTs examined non-pharmacological interventions and 19 examined pharmacological interventions. Effective pharmacological treatments included amantadine and dexmedetomidine. Effective non-pharmacological interventions included sensory stimulation in the acute phase, anger self-management programs, peer mentoring, problem-solving, and emotional regulation. Psychotherapy showed conflicting evidence.

CONCLUSION

This evidence-based review provides a comprehensive overview of the research landscape of RCTs addressing behavior post-MSTBI. The findings from these RCTs may be valuable for health care professionals, researchers, and policymakers involved in the field of TBI and behavior.

Targeting of nanoparticles to the cerebral vasculature after traumatic brain injury

Traumatic brain injury has faced numerous challenges in drug development, primarily due to the difficulty of effectively delivering drugs to the brain. However, there is a potential solution in targeted drug delivery methods involving antibody-drug conjugates or nanocarriers conjugated with targeting antibodies. Following a TBI, the blood-brain barrier (BBB) becomes permeable, which can last for years and allow the leakage of harmful plasma proteins. Consequently, an appealing approach for TBI treatment involves using drug delivery systems that utilize targeting antibodies and nanocarriers to help restore BBB integrity. In our investigation of this strategy, we examined the efficacy of free antibodies and nanocarriers targeting a specific endothelial surface marker called vascular cell adhesion molecule-1 (VCAM-1), which is known to be upregulated during inflammation. In a mouse model of TBI utilizing central fluid percussion injury, free VCAM-1 antibody did not demonstrate superior targeting when comparing sham vs. TBI brain. However, the administration of VCAM-1-targeted nanocarriers (liposomes) exhibited a 10-fold higher targeting specificity in TBI brain than in sham control. Flow cytometry and confocal microscopy analysis confirmed that VCAM-1 liposomes were primarily taken up by brain endothelial cells post-TBI. Consequently, VCAM-1 liposomes represent a promising platform for the targeted delivery of therapeutics to the brain following traumatic brain injury.

Weight-Drop Method for Inducing Closed Head Diffuse Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the foremost causes of disability and death globally. Prerequisites for successful therapy of disabilities associated with TBI involved improved knowledge of the neurobiology of TBI, measurement of quantitative changes in recovery dynamics brought about by therapy, and the translation of quantitative methodologies and techniques that were successful in tracking recovery in preclinical models to human TBI. Frequently used animal models of TBI in research and development include controlled cortical impact, fluid percussion injury, blast injury, penetrating blast brain injury, and weight-drop impact acceleration models. Preclinical models of TBI benefit from controlled injury settings and the best prospects for biometric quantification of injury and therapy-induced gradual recovery from disabilities. Impact acceleration closed head TBI paradigm causes diffuse TBI (DTBI) without substantial focal brain lesions in rats. DTBI is linked to a significant rate of death, morbidity, and long-term disability. DTBI is difficult to diagnose at the time of hospitalization with imaging techniques making it challenging to take prompt therapeutic action. The weight-drop method without craniotomy is an impact acceleration closed head DTBI model that is used to induce mild/moderate diffuse brain injuries in rodents. Additionally, we have characterized neuropathological and neurobehavioral outcomes of the weight-drop model without craniotomy for inducing closed head DTBI of graded severity with a range of mass of weights (50-450 gm). This chapter also discusses techniques and protocols for measuring numerous functional disabilities and pathological changes in the brain brought on by DTBI.

Memantine inhibits cortical spreading depolarization and improves neurovascular function following repetitive traumatic brain injury

Cortical spreading depolarization (CSD) is a promising target for neuroprotective therapy in traumatic brain injury (TBI). We explored the effect of NMDA receptor antagonism on electrically triggered CSDs in healthy and brain-injured animals. Rats received either one moderate or four daily repetitive mild closed head impacts (rmTBI). Ninety-three animals underwent craniectomy with electrocorticographic (ECoG) and local blood flow monitoring. In brain-injured animals, ketamine or memantine inhibited CSDs in 44 to 88% and 50 to 67% of cases, respectively. Near-DC/AC-ECoG amplitude was reduced by 44 to 75% and 52 to 67%, and duration by 39 to 87% and 61 to 78%, respectively. Daily memantine significantly reduced spreading depression and oligemia following CSD. Animals (N = 31) were randomized to either memantine (10 mg/kg) or saline with daily neurobehavioral testing. Memantine-treated animals had higher neurological scores. We demonstrate that memantine improved neurovascular function following CSD in sham and brain-injured animals. Memantine also prevented neurological decline in a blinded, preclinical randomized rmTBI trial.

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.

NS1619 Alleviate Brain-Derived Extracellular Vesicle-Induced Brain Injury by Regulating BKca Channel and Nrf2/HO-1/NF-ĸB Pathway

Brain induced extracellular vesicle (BDEV) elevates after traumatic brain injury (TBI) and contributes to secondary brain injury. However, the role of BDEV in TBI remains unclear. In this study, we determined the mechanisms of BDEV in brain injury and explored whether neuroprotective drug BKca channel opener NS1619 may attenuate BDEV-induced brain injury. We injected BDEV and lactadherin, respectively, to mimic the up and downregulation of BDEV after TBI and illustrated the role of BDEV in vivo. In vitro, the membrane potential and calcium concentration of HT-22, bEnd3, and BV-2 were measured by fluorescent staining. The effects of BDEV and NS1619 on HT-22 were evaluated by CCK-8, LDH release assay, Na⁺/k⁺-ATPase activity, JC-1 staining, DHE staining, and 4-HNE staining, respectively. The role of BDEV and NS1619 on the Nrf2/HO-1/p65 pathway was also evaluated in HT-22. Finally, we administrated TBI mice with NS1619 to clarify the role of NS1619 against BDEV in vivo. Our results suggested that BDEV aggravated and lactadherin mitigated TBI-induced EB leakage, brain edema, neuronal degeneration, apoptosis, ROS level, microgliosis, MMP-9 activity, and NF-κB activation. In vitro, BDEV-caused depolarized membrane potential and calcium overload were significantly attenuated by NS1619 in HT-22, bEnd3, and BV-2. BDEV markedly decreased cell viability, Na⁺/k⁺-ATPase activity, and caused mitochondrial dysregulation, oxidative stress, and NF-ĸB activation. NS1619 pretreatment alleviated above process and enhanced antioxidant system Nrf2/HO-1 in HT-22. Finally, NS1619 administration significantly inhibited neuroinflammation response and improved TBI outcome after TBI. NS1619 treatment also reduced 4-HNE content and NF-ĸB activation and enhanced Nrf2/HO-1 pathway. Our data showed that BDEV aggravated brain injury by perturbing cell membrane potential, calcium homeostasis, oxidative stress, and neuroinflammation. The BKca channel opener NS1619 attenuated BDEV-induced pathological process in vitro and in vivo by modulating the BKca channel and Nrf2/HO-1/NF-ĸB pathway.

Serum Progesterone Levels as Predictor of Outcome in Severe Traumatic Brain Injury: Analysis of Cohort of 100 Patients

Despite advances in research and improved neurological intensive care in recent years, the clinical outcome of severely head injured patients is still poor. Primary insult is followed by a complex cascade of molecular and biochemical events that lead to neuroinflammation, brain edema, and delayed neuronal death. No specific pharmacological therapy is currently available which prevents the development of secondary brain injuries, and most therapeutic strategies have failed in translation from bench to bedside. There are limitations of clinical and radiological methods in delineating the exact severity and prognosis of traumatic brain injury (TBI). A myriad complex biochemical markers are under investigation to delineate the extent of brain tissue damage and to independently predict the outcome, but a search for simple biomarker still eludes the research. Progesterone, a gonadal hormone and a neurosteroid, although controversial as a neuroprotective agent, may hold promise as a simple biochemical marker of the outcome in severe TBI.

Efficacy of prophylactic versus therapeutic administration of the NMDA receptor antagonist MK-801 on the acute neurochemical response to a concussion in a rat model combining force and rotation

OBJECTIVE

Alterations in amino acid concentrations are a major contributor to the persistent neurological and behavioral effects induced by concussions and mild traumatic brain injuries (TBIs). Glutamate, the most abundant excitatory amino acid in the CNS, has a major role in the pathophysiological process of concussion. The indiscriminate liberation of glutamate immediately after a concussion triggers an excitotoxic response that leads to cell death, neuronal damage, and the dysfunction of surviving neurons, largely by overactivation of N-methyl-d-aspartate (NMDA) glutamatergic receptors. The aim of the present study was to investigate the efficacy of prophylactic versus therapeutic administration of MK-801, a promising NMDA receptor antagonist, on the acute changes in amino acid extracellular concentrations involved in excitotoxicity resulting from a concussive trauma.

METHODS

The immediate neurochemical response to a concussion cannot be characterized in humans. Therefore, the authors used their previously validated combination of a weight-drop concussion rat model and in vivo cerebral microdialysis. The microdialysis probe was inserted inside the hippocampus and left inserted at impact to allow uninterrupted sampling of amino acids of interest immediately after concussion. The primary outcome included amino acid concentrations and the secondary outcome included righting time. Samples were taken in 10-minute increments for 60 minutes before, during, and 60 minutes after impact, and analyzed for glutamate, gamma-aminobutyric acid, taurine, glycine, glutamine, and serine using high-performance liquid chromatography. Righting time was acquired as a neurological restoration indicator. Physiological saline or 10 mg/kg MK-801 was administrated intraperitoneally 60 minutes before or immediately following induction of sham injury or concussion.

RESULTS

Following induction of concussion, glutamate, taurine, and glycine levels as well as righting times in cases from the MK-801 treatment group were comparable to those of vehicle-treated animals. In contrast, righting times and amino acid concentrations observed within the first 10 minutes after induction of concussion in cases assigned to the MK-801 prophylaxis group were comparable to those of sham-injured animals.

CONCLUSIONS

These results suggest that presynaptic actions and peak availability of MK-801 following prophylactic administration significantly inhibit the immediate and indiscriminate release of glutamate, taurine, and glycine in extracellular fluid after a concussion.

Neurogenic induction of human dental pulp derived stem cells by hanging drop technique, basic fibroblast growth factor, and SHH factors

BACKGROUND

The progressive destruction of nerve cells in nervous system will induce neurodegenerative diseases. Recently, cell-based therapies have attracted the attention of researchers in the treatment of these abnormal conditions. Thus, the aim of this study was to provide a simple and efficient way to differentiate human dental pulp stem cells into neural cell-like to achieve a homogeneous population of these cells for transplantation in neurodegenerative diseases.

MATERIALS AND METHODS

In this basic research, human dental pulp stem cells were isolated and characterized by immunocytochemistry and flow cytometry techniques. In the following, the cells were cultured using hanging drop as three-dimensional (3D) and tissue culture plate as 2D techniques. Subsequently, cultured cells were differentiated into neuron cell-like in the presence of FGF and Sonic hedgehog (SHH) factors. Finally, the percentage of cells expressing Neu N and β tubulin III markers was determined using immunocytochemistry technique. Finally, all data were analyzed using the SPSS software.

RESULTS

Flow cytometry and immunocytochemistry results indicated that human dental pulp-derived stem cells were CD90, CD106-positive, but were negative for CD34, CD45 markers (P ≤ 0.001). In addition, the mean percentage of β tubulin positive cells in different groups did not differ significantly from each other (P ≥ 0.05). Nevertheless, the mean percentage of Neu N-positive cells was significantly higher in differentiated cells with embryoid bodies' source, especially in the presence of SHH than other groups (P ≤ 0.05).

CONCLUSION

It is concluded that due to the wide range of SHH functions and the facilitation of intercellular connections in the hanging droop method, it is recommended that the use of hanging drop method and SHH factor can be effective in increasing the efficiency of cell differentiation.

Neuroprotective effect of minocycline against acute brain injury in clinical practice: A systematic review

Acute brain injury is a leading cause of morbidity and mortality worldwide. The term is inclusive of traumatic brain injury, cerebral ischemia, subarachnoid hemorrhage, and intracerebral hemorrhage. Current pharmacologic treatments have had minimal effect on improving neurological outcomes leading to a significant interest in the development neuroprotective agents. Minocycline is a second-generation tetracycline with high blood brain barrier penetrance due to its lipophilic properties. It functions across multiple molecular pathways involved in secondary-injury cascades following acute brain injury. Animal model studies suggest that minocycline might lead to improved neurologic outcomes, but few such trials exist in humans. Clinical investigations have been limited to small randomized trials in ischemic stroke patients which have not demonstrated a clear advantage in neurologic outcomes, but also have not been sufficiently powered to draw definitive conclusions. The potential neuroprotective effect of minocycline in the setting of traumatic brain injury, subarachnoid hemorrhage, and intracerebral hemorrhage have all been limited to pilot studies with phase II/III investigations pending. The authors aim to synthesize what is currently known about minocycline as a neuroprotective agent against acute brain injury in humans.

Glycyrrhizin Blocks the Detrimental Effects of HMGB1 on Cortical Neurogenesis After Traumatic Neuronal Injury

Despite medical advances, neurological recovery after severe traumatic brain injury (TBI) remains poor. Elevated levels of high mobility group box protein-1 (HMGB1) are associated with poor outcomes; likely via interaction with receptors for advanced-glycation-end-products (RAGE). We examined the hypothesis that HMGB1 post-TBI is anti-neurogenic and whether this is pharmacologically reversible. Post-natal rat cortical mixed neuro-glial cell cultures were subjected to needle-scratch injury and examined for HMGB1-activation/neuroinflammation. HMGB1-related genes/networks were examined using genome-wide RNA-seq studies in cortical perilesional tissue samples from adult mice. Post-natal rat cortical neural stem/progenitor cell cultures were generated to quantify effects of injury-condition medium (ICM) on neurogenesis with/without RAGE antagonist glycyrrhizin. Needle-injury upregulated TNF-α/NOS-2 mRNA-expressions at 6 h, increased proportions of activated microglia, and caused neuronal loss at 24 h. Transcriptome analysis revealed activation of HMGB1 pathway genes/canonical pathways in vivo at 24 h. A 50% increase in HMGB1 protein expression, and nuclear-to-cytoplasmic translocation of HMGB1 in neurons and microglia at 24 h post-injury was demonstrated in vitro. ICM reduced total numbers/proportions of neuronal cells, but reversed by 0.5 μM glycyrrhizin. HMGB1 is activated following in vivo post mechanical injury, and glycyrrhizin alleviates detrimental effects of ICM on cortical neurogenesis. Our findings highlight glycyrrhizin as a potential therapeutic agent post-TBI.

Perinatal IL-1β-induced inflammation suppresses Tbr2+ intermediate progenitor cell proliferation in the developing hippocampus accompanied by long-term behavioral deficits

Meta-analyses have revealed associations between the incidence of maternal infections during pregnancy, premature birth, smaller brain volumes, and subsequent cognitive, motor and behavioral deficits as these children mature. Inflammation during pregnancy in rodents produces cognitive and behavioral deficits in the offspring that are similar to those reported in human studies. These deficits are accompanied by decreased neurogenesis and proliferation in the subgranular zone (SGZ) of the dentate gyrus (DG) of the hippocampus. As systemically administering interleukin-1 β (IL-1β) to neonatal mice recapitulates many of the brain abnormalities seen in premature babies including developmental delays, the goal of this study was to determine whether IL-1-mediated neuroinflammation would affect hippocampal growth during development to produce cognitive and behavioral abnormalities. For these studies, 10 ​ng/g IL-1β was administered twice daily to Swiss Webster mice during the first 5 days of life, which increased hippocampal levels of IL-1α and acutely reduced the proliferation of Tbr2+ neural progenitors in the DG. In vitro, both IL-1α and IL-1β produced G1/S cell cycle arrest that resulted in reduced progenitor cell proliferation within the transit amplifying progenitor cell cohort. By contrast, IL-1β treatment increased neural stem cell frequency. Upon terminating IL-1β treatment, the progenitor cell pool regained its proliferative capacity. An earlier study that used this in vivo model of perinatal inflammation showed that mice that received IL-1β as neonates displayed memory deficits which suggested abnormal hippocampal function. To evaluate whether other cognitive and behavioral traits associated with hippocampal function would also be altered, mice were tested in tasks designed to assess exploratory and anxiety behavior as well as working and spatial memory. Interestingly, mice that received IL-1β as neonates showed signs of anxiety in several behavioral assays during adolescence that were also evident in adulthood. Additionally, these mice did not display working memory deficits in adulthood, but they did display deficits in long-term spatial memory. Altogether, these data support the view that perinatal inflammation negatively affects the developing hippocampus by producing behavioral deficits that persist into adulthood. These data provide a new perspective into the origin of the cognitive and behavioral impairments observed in prematurely-born sick infants.

Glia Maturation Factor (GMF) Regulates Microglial Expression Phenotypes and the Associated Neurological Deficits in a Mouse Model of Traumatic Brain Injury

Traumatic brain injury (TBI) induces inflammatory responses through microglial activation and polarization towards a more inflammatory state that contributes to the deleterious secondary brain injury. Glia maturation factor (GMF) is a pro-inflammatory protein that is responsible for neuroinflammation following insult to the brain, such as in TBI. We hypothesized that the absence of GMF in GMF-knockout (GMF-KO) mice would regulate microglial activation state and the M1/M2 phenotypes following TBI. We used the weight drop model of TBI in C57BL/6 mice wild-type (WT) and GMF-KO mice. Immunofluorescence staining, Western blot, and ELISA assays were performed to confirm TBI-induced histopathological and neuroinflammatory changes. Behavioral analysis was done to check motor coordination ability and cognitive function. We demonstrated that the deletion of GMF in GMF-KO mice significantly limited lesion volume, attenuated neuronal loss, inhibited gliosis, and activated microglia adopted predominantly anti-inflammatory (M2) phenotypes. Using an ELISA method, we found a gradual decrease in pro-inflammatory cytokines (TNF-α and IL-6) and upregulation of anti-inflammatory cytokines (IL-4 and IL-10) in GMF-KO mice compared with WT mice, thus, promoting the transition of microglia towards a more predominantly anti-inflammatory (M2) phenotype. GMF-KO mice showed significant improvement in motor ability, memory, and cognition. Overall, our results demonstrate that GMF deficiency regulates microglial polarization, which ameliorates neuronal injury and behavioral impairments following TBI in mice and concludes that GMF is a regulator of neuroinflammation and an ideal therapeutic target for the treatment of TBI.

Neuroprotective Potentials of Marine Algae and Their Bioactive Metabolites: Pharmacological Insights and Therapeutic Advances

Beyond their significant contribution to the dietary and industrial supplies, marine algae are considered to be a potential source of some unique metabolites with diverse health benefits. The pharmacological properties, such as antioxidant, anti-inflammatory, cholesterol homeostasis, protein clearance and anti-amyloidogenic potentials of algal metabolites endorse their protective efficacy against oxidative stress, neuroinflammation, mitochondrial dysfunction, and impaired proteostasis which are known to be implicated in the pathophysiology of neurodegenerative disorders and the associated complications after cerebral ischemia and brain injuries. As was evident in various preclinical studies, algal compounds conferred neuroprotection against a wide range of neurotoxic stressors, such as oxygen/glucose deprivation, hydrogen peroxide, glutamate, amyloid β, or 1-methyl-4-phenylpyridinium (MPP+) and, therefore, hold therapeutic promise for brain disorders. While a significant number of algal compounds with promising neuroprotective capacity have been identified over the last decades, a few of them have had access to clinical trials. However, the recent approval of an algal oligosaccharide, sodium oligomannate, for the treatment of Alzheimer's disease enlightened the future of marine algae-based drug discovery. In this review, we briefly outline the pathophysiology of neurodegenerative diseases and brain injuries for identifying the targets of pharmacological intervention, and then review the literature on the neuroprotective potentials of algal compounds along with the underlying pharmacological mechanism, and present an appraisal on the recent therapeutic advances. We also propose a rational strategy to facilitate algal metabolites-based drug development.

Formoterol, a β2-adrenoreceptor agonist, induces mitochondrial biogenesis and promotes cognitive recovery after traumatic brain injury

Traumatic brain injury (TBI) leads to acute necrosis at the site of injury followed by a sequence of secondary events lasting from hours to weeks and often years. Targeting mitochondrial impairment following TBI has shown improvements in brain mitochondrial bioenergetics and neuronal function. Recently formoterol, a highly selective β₂-adrenoreceptor agonist, was found to induce mitochondrial biogenesis (MB) via Gβγ-Akt-eNOS-sGC pathway. Activation of MB is a novel approach that has been shown to restore mitochondrial function in several disease and injury models. We hypothesized that activation of MB as a target of formoterol after TBI would mitigate mitochondrial dysfunction, enhance neuronal function and improve behavioral outcomes. TBI-injured C57BL/6 male mice were injected (i.p.) with vehicle (normal saline) or formoterol (0.3 mg/kg) at 15 min, 8 h, 16 h, 24 h and then daily after controlled cortical impact (CCI) until euthanasia. After CCI, mitochondrial copy number and bioenergetic function were decreased in the ipsilateral cortex of the CCI-vehicle group. Compared to CCI-vehicle, cortical and hippocampal mitochondrial respiration rates as well as cortical mitochondrial DNA copy number were increased in the CCI-formoterol group. Mitochondrial Ca²⁺ buffering capacity in the hippocampus was higher in the CCI-formoterol group compared to CCI-vehicle group. Both assessments of cognitive performance, novel object recognition (NOR) and Morris water maze (MWM), decreased following CCI and were restored in the CCI-formoterol group. Although no changes were seen in the amount of cortical tissue spared between CCI-formoterol and CCI-vehicle groups, elevated levels of hippocampal neurons and improved white matter sparing in the corpus callosum were observed in CCI-formoterol group. Collectively, these results indicate that formoterol-mediated MB activation may be a potential therapeutic target to restore mitochondrial bioenergetics and promote functional recovery after TBI.

Potential of mesenchymal stem cells alone, or in combination, to treat traumatic brain injury

Traumatic brain injury (TBI) causes death and disability in the United States and around the world. The traumatic insult causes the mechanical injury of the brain and primary cellular death. While a comprehensive pathological mechanism of TBI is still lacking, the focus of the TBI research is concentrated on understanding the pathophysiology and developing suitable therapeutic approaches. Given the complexities in pathophysiology involving interconnected immunologic, inflammatory, and neurological cascades occurring after TBI, the therapies directed to a single mechanism fail in the clinical trials. This has led to the development of the paradigm of a combination therapeutic approach against TBI. While there are no drugs available for the treatment of TBI, stem cell therapy has shown promising results in preclinical studies. But, the success of the therapy depends on the survival of the stem cells, which are limited by several factors including route of administration, health of the administered cells, and inflammatory microenvironment of the injured brain. Reducing the inflammation prior to cell administration may provide a better outcome of cell therapy following TBI. This review is focused on different therapeutic approaches of TBI and the present status of the clinical trials.

Evaluation of the effects of pycnogenol (French maritime pine bark extract) supplementation on inflammatory biomarkers and nutritional and clinical status in traumatic brain injury patients in an intensive care unit: A randomized clinical trial protocol

Background

Traumatic brain injury (TBI) is one of the major health and socioeconomic problems in the world. Immune-enhancing enteral formula has been proven to significantly reduce infection rate in TBI patients. One of the ingredients that can be used in immunonutrition formulas to reduce inflammation and oxidative stress is pycnogenol.

Objective

The objective of this work is to survey the effect of pycnogenol on the clinical, nutritional, and inflammatory status of TBI patients.

Methods

This is a double-blind, randomized controlled trial. Block randomization will be used. An intervention group will receive pycnogenol supplementation of 150 mg for 10 days and a control group will receive a placebo for the same duration. Inflammatory status (IL-6, IL- 1β, C-reactive protein) and oxidative stress status (malondialdehyde, total antioxidant capacity), at the baseline, at the 5th day, and at the end of the study (10th day) will be measured. Clinical and nutritional status will be assessed three times during the intervention. The Sequential Organ Failure Assessment (SOFA) questionnaire for assessment of organ failure will be filled out every other day. The mortality rate will be calculated within 28 days of the start of the intervention. Weight, body mass index, and body composition will be measured. All analyses will be conducted by an initially assigned study arm in an intention-to-treat analysis.

Discussion

We expect that supplementation of 150 mg pycnogenol for 10 days will improve clinical and nutritional status and reduce the inflammation and oxidative stress of the TBI patients.

Trial registration

This trial is registered at clinicaltrials.gov (ref: NCT03777683) at 12/13/2018.

Mortality and Associated Morbidities Following Traumatic Brain Injury in Older Medicare Statin Users

OBJECTIVE

To assess the relationship between posttraumatic brain injury statin use and (1) mortality and (2) the incidence of associated morbidities, including stroke, depression, and Alzheimer's disease and related dementias following injury.

SETTING AND PARTICIPANTS

Nested cohort of all Medicare beneficiaries 65 years of age and older who survived a traumatic brain injury (TBI) hospitalization during 2006 through 2010. The final sample comprised 100 515 beneficiaries.

DESIGN

Retrospective cohort study of older Medicare beneficiaries. Relative risks (RR) and 95% confidence interval (CI) were obtained using discrete time analysis and generalized estimating equations.

MEASURES

The exposure of interest included monthly atorvastatin, fluvastatin, lovastatin, pravastatin, rosuvastatin, and simvastatin use. Outcomes of interest included mortality, stroke, depression, and Alzheimer's disease and related dementias.

RESULTS

Statin use of any kind was associated with decreased mortality following TBI hospitalization discharge. Any statin use was also associated with a decrease in any stroke (RR, 0.86; 95% confidence intervals (CI), 0.81-0.91), depression (RR, 0.85; 95% CI, 0.79-0.90), and Alzheimer's disease and related dementias (RR, 0.77; 95% CI, 0.73-0.81).

CONCLUSION

These findings provide valuable information for clinicians treating older adults with TBI as clinicians can consider, when appropriate, atorvastatin and simvastatin to older adults with TBI in order to decrease mortality and associated morbidities.

Why Does Brain Trauma Research Fail?

Traumatic brain injury (TBI) represents a major health care problem and a significant social and economic issue worldwide. Considering the generalized failure in introducing effective drugs and clinical protocols, there is an urgent need for efficient treatment modalities, able to improve devastating posttraumatic morbidity and mortality. In this work, the status of brain trauma research is analyzed in all its aspects, including basic and translational science and clinical trials. Implicit and explicit challenges to different lines of research are discussed and clinical trial structures and outcomes are scrutinized, along with possible explanations for systematic therapeutic failures and their implications for future development of drug and clinical trials. Despite significant advances in basic and clinical research in recent years, no specific therapeutic protocols for TBI have been shown to be effective. New potential therapeutic targets have been identified, following a better understanding of pathophysiologic mechanisms underlying TBI, although with disappointing results. Several reasons can be pinpointed at different levels, from inaccurate animal models of disease to faulty preclinical and clinical trials, with poor design and subjective outcome measures. Distinct strategies can be delineated to overcome specific shortcomings of research studies. Identifying and contextualizing the failures that have dominated TBI research is mandatory. This review analyzes current approaches and discusses possible strategies for improving outcomes.

Anti-inflammatory Effects of Traditional Chinese Medicines on Preclinical in vivo Models of Brain Ischemia-Reperfusion-Injury: Prospects for Neuroprotective Drug Discovery and Therapy

Acquired brain ischemia-and reperfusion-injury (IRI), including both Ischemic stroke (IS) and Traumatic Brain injury (TBI), is one of the most common causes of disability and death in adults and represents a major burden in both western and developing countries worldwide. China’s clinical neurological therapeutic experience in the use of traditional Chinese medicines (TCMs), including TCM-derived active compounds, Chinese herbs, TCM formulations and decoction, in brain IRI diseases indicated a trend of significant improvement in patients’ neurological deficits, calling for blind, placebo-controlled and randomized clinical trials with careful meta-analysis evaluation. There are many TCMs in use for brain IRI therapy in China with significant therapeutic effects in preclinical studies using different brain IRI-animal. The basic hypothesis in this field claims that in order to avoid the toxicity and side effects of the complex TCM formulas, individual isolated and identified compounds that exhibited neuroprotective properties could be used as lead compounds for the development of novel drugs. China’s efforts in promoting TCMs have contributed to an explosive growth of the preclinical research dedicated to the isolation and identification of TCM-derived neuroprotective lead compounds. Tanshinone, is a typical example of TCM-derived lead compounds conferring neuroprotection toward IRI in animals with brain middle cerebral artery occlusion (MCAO) or TBI models. Recent reports show the significance of the inflammatory response accompanying brain IRI. This response appears to contribute to both primary and secondary ischemic pathology, and therefore anti-inflammatory strategies have become popular by targeting pro-inflammatory and anti-inflammatory cytokines, other inflammatory mediators, reactive oxygen species, nitric oxide, and several transcriptional factors. Here, we review recent selected studies and discuss further considerations for critical reevaluation of the neuroprotection hypothesis of TCMs in IRI therapy. Moreover, we will emphasize several TCM’s mechanisms of action and attempt to address the most promising compounds and the obstacles to be overcome before they will enter the clinic for IRI therapy. We hope that this review will further help in investigations of neuroprotective effects of novel molecular entities isolated from Chinese herbal medicines and will stimulate performance of clinical trials of Chinese herbal medicine-derived drugs in IRI patients.

Reduced Neuroinflammation and Improved Functional Recovery after Traumatic Brain Injury by Prophylactic Diet Supplementation in Mice

Currently, there are no approved therapeutic drugs for the treatment of traumatic brain injury (TBI), and new targets and approaches are needed to provide relief from the long-term effects of TBI. Recent studies suggest that nutrition plays a critical role in improving the outcome from TBI in both civilians and military personnel. We have previously shown that GrandFusion^® (GF) diets improved recovery from cerebral ischemia and enhanced physical activity and endurance in rodent models. We, therefore, sought to determine the impact of a prophylactic diet enriched in fruits and vegetables on recovery from TBI in the controlled cortical impact rodent model. Results demonstrated that mice fed the diets had improved neuromotor function, reduced lesion volume, increased neuronal density in the hippocampus and reduced inflammation. As previously shown, TBI increases cathepsin B as part of the inflammasome complex resulting in elevated inflammatory markers like interleukin-1β (IL-1β). Consumption of the GF diets attenuated the increase in cathepsin B levels and prevented the increase in the proapoptotic factor Bax following TBI. These data suggest that prior consumption of diets enriched in fruits and vegetables either naturally or through powdered form can provide protection from the detrimental effects of TBI.

Unfolding the pleiotropic facades of rosuvastatin in therapeutic intervention of myriads of neurodegenerative disorders

Rosuvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme (HMG-CoA) reductase inhibitor, and one of the most popular antihyperlipidemic medications have been found to possess pharmacodynamic activities much different from its usual indication. Recent research studies have revealed the efficacy of rosuvastatin in attenuating neuroinflammation, reducing the progression of Alzheimer's disease, providing protection against cerebral ischaemia and spinal cord injury as well as ameliorating epilepsy. Mechanisms behind the neuroprotective potential of rosuvastatin can be attributed to its pleiotropic effects, independent of its ability to inhibit HMG-CoA reductase. These processes include modulation of several cellular pathways, isoprenylation, effects on oxidative stress, nitrosative levels, inflammation, and immune response. This review aims to assimilate and summarize recent findings on the pharmacological actions of rosuvastatin in attenuating neurological disorders in order to guide future research in this space.

Delayed and Abbreviated Environmental Enrichment after Brain Trauma Promotes Motor and Cognitive Recovery That Is Not Contingent on Increased Neurogenesis

Environmental enrichment (EE) confers motor and cognitive recovery in pre-clinical models of traumatic brain injury (TBI), and neurogenesis has been attributed to mediating the benefits. Whether that ascription is correct has not been fully investigated. Hence, the goal of the current study is to further clarify the possible role of learning-induced hippocampal neurogenesis on functional recovery after cortical impact or sham injury by utilizing two EE paradigms (i.e., early + continuous, initiated immediately after TBI and presented 24 h/day; and delayed + abbreviated, initiated 4 days after TBI for 6 h/day) and comparing them to one another as well as to standard (STD) housed controls. Motor and cognitive performance was assessed on post-operative Days 1-5 and 14-19, respectively, for the STD and early + continuous EE groups and on Days 4-8 and 17-22, for the delayed + abbreviated EE groups. Rats were injected with bromodeoxyuridine (BrdU, 500 mg/ kg; intraperitoneally) for 3 days (12 h apart) before cognitive training and sacrificed 1 week later for quantification of BrdU+ and doublecortin (DCX+) labeled cells. Both early + continuous and delayed + abbreviated EE promoted motor and cognitive recovery after TBI, relative to STD (p < 0.05), and did not differ from one another (p > 0.05). However, only early + continuous EE increased DCX+ cells beyond the level of STD-housed controls (p < 0.05). No effect of EE on non-injured controls was observed. Based on these data, two novel conclusions emerged. First, EE does not need to be provided early and continuously after TBI to confer benefits, which lends credence to the delayed + abbreviated EE paradigm as a relevant pre-clinical model of neurorehabilitation. Second, the functional recovery observed after TBI in the delayed + abbreviated EE paradigm is not contingent on increased hippocampal neurogenesis. Future studies will elucidate alternate viable mechanisms mediating the benefits induced by EE.

Perioperative Management of Severe Traumatic Brain Injury: What Is New?

PURPOSE OF THE REVIEW

Severe traumatic brain injury (TBI) continues to represent a global public health issue, and mortality and morbidity in TBI patients remain substantial. There are ongoing international collaborations to provide guidelines for perioperative care and management of severe TBI patients. In addition, new pharmacologic agents are being tested along with cognitive rehabilitation to improve functional independence and outcome in TBI patients. This review will discuss the current updates in the guidelines for the perioperative management of TBI patients and describe potential new therapies to improve functional outcomes.

RECENT FINDINGS

In the most recent guidelines published by The Brain Trauma Foundation, therapeutic options were reviewed based on new and revised evidence or lack of evidence. For example, changes and/or updates were made to the recommendations for the use of sedation and hypothermia in TBI patients, and new evidence was provided for the use of cerebrospinal fluid drainage as a first-line treatment for increased intracranial pressure (ICP). In addition to the guidelines, new 'multi-potential' agents that can target several mechanisms are being tested along with cognitive rehabilitation.

SUMMARY

The major goal of perioperative management of TBI patients is to prevent secondary damage. Therapeutic measures based on established guidelines and recommendations must be instituted promptly throughout the perioperative course to reduce morbidity and mortality.

FGF21 Protects the Blood-Brain Barrier by Upregulating PPARγ via FGFR1/β-klotho after Traumatic Brain Injury

Blood-brain barrier (BBB) disruption and dysfunction result in brain edema, which is responsible for more than half of all deaths after severe traumatic brain injury (TBI). Fibroblast growth factor 21 (FGF21) has a potential neuroprotective function in the brain. However, the effects and underlying possible mechanism of action on BBB integrity following TBI remain unknown. The purpose of the current study was to determine the effects of FGF21 on BBB protection and TBI treatment. The effects of recombinant human FGF21 (rhFGF21) on BBB integrity and on tight junction (TJ) and adhesion junction (AJ) proteins were investigated both in a TBI mouse model and an in vitro BBB disruption model established with tumor necrosis factor alpha (TNF-α)-induced human brain microvascular endothelial cells (HBMECs). The ability of rhFGF21 to form an FGF21/FGFR1/β-klotho complex was confirmed by in vitro β-klotho small interfering RNA (siRNA) transfection and FGFR1 co-immunoprecipitation. In addition, the specific FGFR1 and peroxisome proliferator-activated receptor gamma (PPARγ) inhibitors PD173074 and GW9662, respectively, were applied to further explore the possible mechanism of rhFGF21 in BBB maintenance after TBI. rhFGF21 markedly reduced neurofunctional behavior deficits and cerebral edema degree, preserved BBB integrity, and recued brain tissue loss and neuron apoptosis in the mouse model after TBI. Both in vivo and in vitro, rhFGF21 upregulated TJ and AJ proteins, thereby preserving the BBB. Moreover, rhFGF21 activated PPARγ in TNF-α-induced HBMECs through formation of an FGF21/FGFR1/β-klotho complex. rhFGF21 protected the BBB through FGF21/FGFR1/β-klotho complex formation and PPARγ activation, which upregulated TJ and AJ proteins.

NADPH oxidases in traumatic brain injury - Promising therapeutic targets?

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Despite intense investigation, no neuroprotective agents for TBI have yet translated to the clinic. Recent efforts have focused on identifying potential therapeutic targets that underlie the secondary TBI pathology that evolves minutes to years following the initial injury. Oxidative stress is a key player in this complex cascade of secondary injury mechanisms and prominently contributes to neurodegeneration and neuroinflammation. NADPH oxidase (NOX) is a family of enzymes whose unique function is to produce reactive oxygen species (ROS). Human post-mortem and animal studies have identified elevated NOX2 and NOX4 levels in the injured brain, suggesting that these two NOXs are involved in the pathogenesis of TBI. In support of this, NOX2 and NOX4 deletion studies have collectively revealed that targeting NOX enzymes can reduce oxidative stress, attenuate neuroinflammation, promote neuronal survival, and improve functional outcomes following TBI. In addition, NOX inhibitor studies have confirmed these findings and demonstrated an extended critical window of efficacious TBI treatment. Finally, the translational potential, caveats, and future directions of the field are highlighted and discussed throughout the review.

Predicting Long-Term Global Outcome after Traumatic Brain Injury: Development of a Practical Prognostic Tool Using the Traumatic Brain Injury Model Systems National Database

For patients surviving serious traumatic brain injury (TBI), families and other stakeholders often desire information on long-term functional prognosis, but accurate and easy-to-use clinical tools are lacking. We aimed to build utilitarian decision trees from commonly collected clinical variables to predict Glasgow Outcome Scale (GOS) functional levels at 1, 2, and 5 years after moderate-to-severe closed TBI. Flexible classification tree statistical modeling was used on prospectively collected data from the TBI-Model Systems (TBIMS) inception cohort study. Enrollments occurred at 17 designated, or previously designated, TBIMS inpatient rehabilitation facilities. Analysis included all participants with nonpenetrating TBI injured between January 1997 and January 2017. Sample sizes were 10,125 (year-1), 8,821 (year-2), and 6,165 (year-5) after cross-sectional exclusions (death, vegetative state, insufficient post-injury time, and unavailable outcome). In our final models, post-traumatic amnesia (PTA) duration consistently dominated branching hierarchy and was the lone injury characteristic significantly contributing to GOS predictability. Lower-order variables that added predictability were age, pre-morbid education, productivity, and occupational category. Generally, patient outcomes improved with shorter PTA, younger age, greater pre-morbid productivity, and higher pre-morbid vocational or educational achievement. Across all prognostic groups, the best and worst good recovery rates were 65.7% and 10.9%, respectively, and the best and worst severe disability rates were 3.9% and 64.1%. Predictability in test data sets ranged from C-statistic of 0.691 (year-1; confidence interval [CI], 0.675, 0.711) to 0.731 (year-2; CI, 0.724, 0.738). In conclusion, we developed a clinically useful tool to provide prognostic information on long-term functional outcomes for adult survivors of moderate and severe closed TBI. Predictive accuracy for GOS level was demonstrated in an independent test sample. Length of PTA, a clinical marker of injury severity, was by far the most critical outcome determinant.

Enhancement of Brain d-Serine Mediates Recovery of Cognitive Function after Traumatic Brain Injury

Cognitive deficits, especially memory loss, are common and devastating neuropsychiatric sequelae of traumatic brain injury (TBI). The deficits may persist for years and may be accompanied by increased risk of developing early- onset dementia. Past attempts to reverse the neuropathological effects of brain injury with glutamate-N-methyl-d-aspartate (NMDA) antagonists failed to show any benefits or worsened the outcome, suggesting that activation, rather than blockage, of the NMDA receptor (NMDAR) may be useful in the subacute period after TBI and stroke. Activation of the NMDAR requires occupation of the glycine-modulatory site by co-agonists to achieve its synaptic functions. Glycine and d-serine are endogenous ligands/co-agonists of synaptic NMDARs in many areas of the mature brain. The aim of the present study was to evaluate the effect of 6-chlorobenzo(d)isoxazol-3-ol (CBIO), an inhibitor of D-amino acid oxidase (DAAO), which degrades d-serine, on cognitive outcome in a mouse model of TBI. Because treating TBI animals with CBIO elevates the endogenous levels of d-serine, we compared this novel treatment with treatment by exogenous d-serine alone and combined with CBIO. The results show that a single treatment (24 h post-injury) with CBIO in the mouse model of closed head injury significantly improves cognitive and motor function, and decreases lesion volume and the inflammatory response. Moreover, the compound proved to be neuroprotective, as the hippocampal volume and the number of neurons in hippocampal regions increased. Treatment with CBIO boosted the NR1 and phospho- NR1 subunits of the NMDAR and affected the CREB, phospho-CREB, and brain-derived neurotropic factor (BDNF) pathways. These findings render CBIO a promising, novel treatment for cognitive impairment following TBI.

Deletion of NADPH oxidase 4 reduces severity of traumatic brain injury

Traumatic brain injury (TBI) contributes to over 30% of injury-related deaths and is a major cause of disability without effective clinical therapies. Oxidative stress contributes to neurodegeneration, neuroinflammation, and neuronal death to amplify the primary injury after TBI. NADPH oxidase (NOX) is a major source of reactive oxygen species following brain injury. Our current study addresses the functional role of the NOX4 isoform in the damaged cortex following TBI. Adult male C57BL/6 J and NOX4^-/- mice received a controlled cortical impact and lesion size, NOX4 expression, oxidative stress, neurodegeneration, and cell death were assessed in the injured cerebral cortex. The results revealed that NOX4 mRNA and protein expression were significantly upregulated at 1-7 days post-TBI in the injured cerebral cortex. Expression of the oxidative stress markers, 8-OHdG, 4-HNE, and nitrotyrosine was upregulated at 2 and 4 days post-TBI in the WT injured cerebral cortex, and nitrotyrosine primarily colocalized with neurons. In the NOX4^-/- mice, expression of these oxidative stress markers, 8-OHdG, 4-HNE, and nitrotyrosine were significantly attenuated at both timepoints. In addition, examination of NOX4^-/- mice revealed a reduced number of apoptotic (TUNEL⁺) and degenerating (FJB⁺) cells in the perilesional cortex after TBI, as well as a smaller lesion size compared with the WT group. The results of this study implicate a functional role for NOX4 in TBI induced oxidative damage and neurodegeneration and raise the possibility that targeting NOX4 may have therapeutic efficacy in TBI.

Environmental enrichment, alone or in combination with various pharmacotherapies, confers marked benefits after traumatic brain injury

Traumatic brain injury (TBI) is a significant health care issue that affects over ten million people worldwide. Treatment options are limited with numerous failures resulting from single therapies. Fortunately, several preclinical studies have shown that combination treatment strategies may afford greater improvement and perhaps can lead to successful clinical translation, particularly if one of the therapies is neurorehabilitation. The aim of this review is to highlight TBI studies that combined environmental enrichment (EE), a preclinical model of neurorehabilitation, with pharmacotherapies. A series of PubMed search strategies yielded only nine papers that fit the criteria. The consensus is that EE provides robust neurobehavioral, cognitive, and histological improvement after experimental TBI and that the combination of EE with some pharmacotherapies can lead to benefits beyond those revealed by single therapies. However, it is noted that EE can be challenged by drugs such as the acetylcholinesterase inhibitor, donepezil, and the antipsychotic drug, haloperidol, which attenuate its efficacy. These findings may help shape clinical neurorehabilitation strategies to more effectively improve patient outcome. Potential mechanisms for the EE and pharmacotherapy-induced effects are also discussed. This article is part of the Special Issue entitled "Neurobiology of Environmental Enrichment".

Rehabilitative Success After Brain Trauma by Augmenting a Subtherapeutic Dose of Environmental Enrichment With Galantamine

BACKGROUND

Environmental enrichment (EE) confers benefits after traumatic brain injury (TBI) when provided daily for > 6 hours, but not 2 or 4 hours, which more accurately reflects the daily amount of clinical rehabilitation. The lack of benefit with sub-therapeutic EE suggests that augmentation with galantamine (GAL), which enhances cognition after TBI, may be indicated to confer benefits.

OBJECTIVE

To test the hypothesis that 2 and 4 hours of EE paired with GAL will provide benefits comparable to 24 hours of EE alone. Moreover, all EE groups will perform better than the standard (STD)-housed GAL group.

METHODS

Anesthetized rats received a TBI or sham injury and then were randomized to receive intraperitoneal injections of GAL (2 mg/kg) or saline vehicle (VEH; 1 mL/kg) beginning 24 hours after surgery and once daily while receiving EE for 2, 4, or 24 hours. Motor and cognitive assessments were conducted on postoperative days 1-5 and 14-19, respectively.

RESULTS

Motor function was significantly improved in the TBI + 24-hour EE group versus the TBI + STD + VEH and TBI + STD + GAL groups ( P < .05). Cognitive performance was enhanced in all EE groups as well as in the TBI + STD + GAL versus TBI + STD + VEH ( P < .05). Moreover, the 2- and 4-hour EE groups receiving GAL did not differ from the 24-hour EE group ( P > .05) and performed better than GAL alone ( P < .05).

CONCLUSIONS

The findings support the hypothesis and have clinical relevance because, often, only brief rehabilitation may be available in the clinic and, thus, augmenting with a pharmacotherapy such as GAL may lead to outcomes that are significantly better than either therapy alone.

Angiotensin II Causes Neuronal Damage in Stretch-Injured Neurons: Protective Effects of Losartan, an Angiotensin T1 Receptor Blocker

Angiotensin II (Ang II) is a mediator of oxidative stress via activation/induction of reactive oxygen and nitrogen species-generating enzymes, NADPH oxidase (NOX) and inducible nitric oxide synthase (iNOS). We investigated the hypothesis that overproduction of Ang II during traumatic brain injury (TBI) induces the activation of the oxidative stress, which triggers neuroinflammation and cell apoptosis in a cell culture model of neuronal stretch injury. We first established that stretch injury causes a rapid increase in the level of Ang II, which causes the release of pro-inflammatory cytokines, IL-1β and TNF-α, via the induction of oxidative stress. Since angiotensin-converting enzyme (ACE) mediates the production of Ang II via the conversion of Ang I into Ang II, we analyzed the expression of ACE by western blotting. Further, we analyzed caspase-3-mediated apoptosis by TUNEL staining and annexin V western blotting. Angiotensin type I (AT₁) receptor antagonist losartan attenuated Ang II-induced oxidative stress and associated neuroinflammation and cell death in cultured neurons. Remarkably, we noticed that the expression of Ang II type 1 receptor (AngT₁R) upregulated in neuronal stretch injury; losartan mitigates this upregulation. Findings from this study significantly extend our understanding of the pathophysiology of TBI and may have significant implications for developing therapeutic strategies for TBI-associated brain dysfunctions.

Effects of AAV-mediated knockdown of nNOS and GPx-1 gene expression in rat hippocampus after traumatic brain injury

Virally mediated RNA interference (RNAi) to knock down injury-induced genes could improve functional outcome after traumatic brain injury (TBI); however, little is known about the consequences of gene knockdown on downstream cell signaling pathways and how RNAi influences neurodegeneration and behavior. Here, we assessed the effects of adeno-associated virus (AAV) siRNA vectors that target two genes with opposing roles in TBI pathogenesis: the allegedly detrimental neuronal nitric oxide synthase (nNOS) and the potentially protective glutathione peroxidase 1 (GPx-1). In rat hippocampal progenitor cells, three siRNAs that target different regions of each gene (nNOS, GPx-1) effectively knocked down gene expression. However, in vivo, in our rat model of fluid percussion brain injury, the consequences of AAV-siRNA were variable. One nNOS siRNA vector significantly reduced the number of degenerating hippocampal neurons and showed a tendency to improve working memory. GPx-1 siRNA treatment did not alter TBI-induced neurodegeneration or working memory deficits. Nevertheless, microarray analysis of laser captured, virus-infected neurons showed that knockdown of nNOS or GPx-1 was specific and had broad effects on downstream genes. Since nNOS knockdown only modestly ameliorated TBI-induced working memory deficits, despite widespread genomic changes, manipulating expression levels of single genes may not be sufficient to alter functional outcome after TBI.

Prehospital Intubation is Associated with Favorable Outcomes and Lower Mortality in ProTECT III

OBJECTIVE

Traumatic brain injury (TBI) causes more than 2.5 million emergency department visits, hospitalizations, or deaths annually. Prehospital endotracheal intubation has been associated with poor outcomes in patients with TBI in several retrospective observational studies. We evaluated the relationship between prehospital intubation, functional outcomes, and mortality using high quality data on clinical practice collected prospectively during a randomized multicenter clinical trial.

METHODS

ProTECT III was a multicenter randomized, double-blind, placebo-controlled trial of early administration of progesterone in 882 patients with acute moderate to severe nonpenetrating TBI. Patients were excluded if they had an index GCS of 3 and nonreactive pupils, those with withdrawal of life support on arrival, and if they had documented prolonged hypotension and/or hypoxia. Prehospital intubation was performed as per local clinical protocol in each participating EMS system. Models for favorable outcome and mortality included prehospital intubation, method of transport, index GCS, age, race, and ethnicity as independent variables. Significance was set at α = 0.05. Favorable outcome was defined by a stratified dichotomy of the GOS-E scores in which the definition of favorable outcome depended on the severity of the initial injury.

RESULTS

Favorable outcome was more frequent in the 349 subjects with prehospital intubation (57.3%) than in the other 533 patients (46.0%, p = 0.003). Mortality was also lower in the prehospital intubation group (13.8% v. 19.5%, p = 0.03). Logistic regression analysis of prehospital intubation and mortality, adjusted for index GCS, showed that odds of dying for those with prehospital intubation were 47% lower than for those that were not intubated (OR = 0.53, 95% CI = 0.36-0.78). 279 patients with prehospital intubation were transported by air. Modeling transport method and mortality, adjusted for index GCS, showed increased odds of dying in those transported by ground compared to those transported by air (OR = 2.10, 95% CI = 1.40-3.15). Decreased odds of dying trended among those with prehospital intubation adjusted for transport method, index GCS score at randomization, age, and race/ethnicity (OR = 0.70, 95% CI = 0.37-1.31).

CONCLUSIONS

In this study that excluded moribund patients, prehospital intubation was performed primarily in patients transported by air. Prehospital intubation and air medical transport together were associated with favorable outcomes and lower mortality. Prehospital intubation was not associated with increased morbidity or mortality regardless of transport method or severity of injury.

Validation of Acoustic Wave Induced Traumatic Brain Injury in Rats

BACKGROUND

This study looked to validate the acoustic wave technology of the Storz-D-Actor that inflicted a consistent closed-head, traumatic brain injury (TBI) in rats. We studied a range of single pulse pressures administered to the rats and observed the resulting decline in motor skills and memory. Histology was observed to measure and confirm the injury insult.

METHODS

Four different acoustic wave pressures were studied using a single pulse: 0, 3.4, 4.2 and 5.0 bar (n = 10 rats per treatment group). The pulse was administered to the left frontal cortex. Rotarod tests were used to monitor the rats' motor skills while the water maze test was used to monitor memory deficits. The rats were then sacrificed ten days post-treatment for histological analysis of TBI infarct size.

RESULTS

The behavioral tests showed that acoustic wave technology administered an effective insult causing significant decreases in motor abilities and memory. Histology showed dose-dependent damage to the cortex infarct areas only.

CONCLUSIONS

This study illustrates that the Storz D-Actor effectively induces a repeatable TBI infarct, avoiding the invasive procedure of a craniotomy often used in TBI research.

Pathological vascular and inflammatory biomarkers of acute- and chronic-phase traumatic brain injury

Given the demand for developing objective methods for characterizing traumatic brain injury (TBI), research dedicated to evaluating putative biomarkers has burgeoned over the past decade. Since it is critical to elucidate the underlying pathological processes that underlie the higher diverse outcomes that follow neurotrauma, considerable efforts have been aimed at identifying biomarkers of both the acute- and chronic-phase TBI. Such information is not only critical for helping to elucidate the pathological changes that lead to poor long-term outcomes following TBI but it may also assist in the identification of possible prevention and interventions for individuals who sustain head trauma. In the current review, we discuss the potential role of vascular dysfunction and chronic inflammation in both acute- and chronic-phase TBI, and we also highlight existing studies that have investigated inflammation biomarkers associated with poorer injury outcome.

Sports-related concussions: diagnosis, complications, and current management strategies

Sports-related concussions (SRCs) are traumatic events that affect up to 3.8 million athletes per year. The initial diagnosis and management is often instituted on the field of play by coaches, athletic trainers, and team physicians. SRCs are usually transient episodes of neurological dysfunction following a traumatic impact, with most symptoms resolving in 7-10 days; however, a small percentage of patients will suffer protracted symptoms for years after the event and may develop chronic neurodegenerative disease. Rarely, SRCs are associated with complications, such as skull fractures, epidural or subdural hematomas, and edema requiring neurosurgical evaluation. Current standards of care are based on a paradigm of rest and gradual return to play, with decisions driven by subjective and objective information gleaned from a detailed history and physical examination. Advanced imaging techniques such as functional MRI, and detailed understanding of the complex pathophysiological process underlying SRCs and how they affect the athletes acutely and long-term, may change the way physicians treat athletes who suffer a concussion. It is hoped that these advances will allow a more accurate assessment of when an athlete is truly safe to return to play, decreasing the risk of secondary impact injuries, and provide avenues for therapeutic strategies targeting the complex biochemical cascade that results from a traumatic injury to the brain.

Pediatric Traumatic Brain Injury and Autism: Elucidating Shared Mechanisms

Pediatric traumatic brain injury (TBI) and autism spectrum disorder (ASD) are two serious conditions that affect youth. Recent data, both preclinical and clinical, show that pediatric TBI and ASD share not only similar symptoms but also some of the same biologic mechanisms that cause these symptoms. Prominent symptoms for both disorders include gastrointestinal problems, learning difficulties, seizures, and sensory processing disruption. In this review, we highlight some of these shared mechanisms in order to discuss potential treatment options that might be applied for each condition. We discuss potential therapeutic and pharmacologic options as well as potential novel drug targets. Furthermore, we highlight advances in understanding of brain circuitry that is being propelled by improved imaging modalities. Going forward, advanced imaging will help in diagnosis and treatment planning strategies for pediatric patients. Lessons from each field can be applied to design better and more rigorous trials that can be used to improve guidelines for pediatric patients suffering from TBI or ASD.

Potassium Aspartate Attenuates Brain Injury Induced by Controlled Cortical Impact in Rats Through Increasing Adenosine Triphosphate (ATP) Levels, Na+/K+-ATPase Activity and Reducing Brain Edema

BACKGROUND Potassium aspartate (PA), as an electrolyte supplement, is widely used in clinical practice. In our previous study, we found PA had neuroprotective effects against apoptosis after cerebral ischemia/reperfusion in rats. In this study, we examine whether PA has protective effects on traumatic brain injury (TBI). MATERIAL AND METHODS TBI was induced by controlled cortical impact (CCI) in rats. Vehicle treatment (control) or PA treatment was administered intraperitoneally at 30 minutes after CCI. The modified neurological severity score (mNSS) and cortical lesion volume were examined. Brain edema and blood-brain barrier (BBB) integrity were measured, as well as brain ATP contents, lactic acid levels, and Na+/K+-ATPase activities. RESULTS We found that CCI induced cortical injury in rats. Acute PA treatment at the dose of 62.5 mg/kg and 125 mg/kg significantly improved neurological deficits (p<0.05 and p<0.001, respectively) and decreased the cortical lesion volume (p<0.05 and p<0.001, respectively) compared with vehicle-only treatment. PA treatment at the dose of 125 mg/kg attenuated brain edema and ameliorated BBB integrity. In addition, PA treatment significantly reduced the loss of ATP (p<0.01), reduced lactic acid levels (p<0.001), and increased the activity of Na+/K+-ATPase (p<0.01). CONCLUSIONS Our results indicate PA has neuroprotective effects on TBI through increasing ATP levels, Na+/K+-ATPase activity, and reducing brain edema. It provides experimental evidence for the clinical application of PA.

EphB3 signaling propagates synaptic dysfunction in the traumatic injured brain

Traumatic brain injury (TBI), ranging from mild concussion to severe penetrating wounds, can involve brain regions that contain damaged or lost synapses in the absence of neuronal death. These affected regions significantly contribute to sensory, motor and/or cognitive deficits. Thus, studying the mechanisms responsible for synaptic instability and dysfunction is important for protecting the nervous system from the consequences of progressive TBI. Our controlled cortical impact (CCI) injury produces ~20% loss of synapses and mild changes in synaptic protein levels in the CA3-CA1 hippocampus without neuronal losses. These synaptic changes are associated with functional deficits, indicated by >50% loss in synaptic plasticity and impaired learning behavior. We show that the receptor tyrosine kinase EphB3 participates in CCI injury-induced synaptic damage, where EphB3(-/-) mice show preserved long-term potentiation and hippocampal-dependent learning behavior as compared with wild type (WT) injured mice. Improved synaptic function in the absence of EphB3 results from attenuation in CCI injury-induced synaptic losses and reduced d-serine levels compared with WT injured mice. Together, these findings suggest that EphB3 signaling plays a deleterious role in synaptic stability and plasticity after TBI.