Characterization of traumatic brain injury in human brains reveals distinct cellular and molecular changes in contusion and pericontusion

Neuroanatomical zones of human traumatic brain injury reveal significant differences in protein profile and protein oxidation: Implications for secondary injury events

Traumatic brain injury (TBI) causes significant neurological deficits and long-term degenerative changes. Primary injury in TBI entails distinct neuroanatomical zones, i.e., contusion (Ct) and pericontusion (PC). Their dynamic expansion could contribute to unpredictable neurological deterioration in patients. Molecular characterization of these zones compared with away from contusion (AC) zone is invaluable for TBI management. Using proteomics-based approach, we were able to distinguish Ct, PC and AC zones in human TBI brains. Ct was associated with structural changes (blood-brain barrier (BBB) disruption, neuroinflammation, axonal injury, demyelination and ferroptosis), while PC was associated with initial events of secondary injury (glutamate excitotoxicity, glial activation, accumulation of cytoskeleton proteins, oxidative stress, endocytosis) and AC displayed mitochondrial dysfunction that could contribute to secondary injury events and trigger long-term degenerative changes. Phosphoproteome analysis in these zones revealed that certain differentially phosphorylated proteins synergistically contribute to the injury events along with the differentially expressed proteins. Non-synaptic mitochondria (ns-mito) was associated with relatively more differentially expressed proteins (DEPs) compared to synaptosomes (Syn), while the latter displayed increased protein oxidation including tryptophan (Trp) oxidation. Proteomic analysis of immunocaptured complex I (CI) from Syn revealed increased Trp oxidation in Ct > PC > AC (vs. control). Oxidized W272 in the ND1 subunit of CI, revealed local conformational changes in ND1 and the neighboring subunits, as indicated by molecular dynamics simulation (MDS). Taken together, neuroanatomical zones in TBI show distinct protein profile and protein oxidation representing different primary and secondary injury events with potential implications for TBI pathology and neurological status of the patients.

Immunocal® limits gliosis in mouse models of repetitive mild-moderate traumatic brain injury

Successive traumatic brain injuries (TBIs) exacerbate neuroinflammation and oxidative stress. No therapeutics exist for populations at high risk of repetitive mild TBIs (rmTBIs). We explored the preventative therapeutic effects of Immunocal®, a cysteine-rich whey protein supplement and glutathione (GSH) precursor, following rmTBI and repetitive mild-moderate TBI (rmmTBI). Populations that suffer rmTBIs largely go undiagnosed and untreated; therefore, we first examined the potential therapeutic effect of Immunocal® long-term following rmTBI. Mice were treated with Immunocal® prior to, during, and following rmTBI induced by controlled cortical impact until analysis at 2 weeks, 2 months, and 6 months following the last rmTBI. Astrogliosis and microgliosis were measured in cortex at each time point and edema and macrophage infiltration by MRI were analyzed at 2 months post-rmTBI. Immunocal® significantly reduced astrogliosis at 2 weeks and 2 months post-rmTBI. Macrophage activation was observed at 2 months post-rmTBI but Immunocal® had no significant effect on this endpoint. We did not observe significant microgliosis or edema after rmTBI. The dosing regimen was repeated in mice subjected to rmmTBI; however, using this experimental paradigm, we examined the preventative therapeutic effects of Immunocal® at a much earlier timepoint because populations that suffer more severe rmmTBIs are more likely to receive acute diagnosis and treatment. Increases in astrogliosis, microgliosis, and serum neurofilament light (NfL), as well as reductions in the GSH:GSSG ratio, were observed 72 h post-rmmTBI. Immunocal® only significantly reduced microgliosis after rmmTBI. In summary, we report that astrogliosis persists for 2 months post-rmTBI and that inflammation, neuronal damage, and altered redox homeostasis present acutely following rmmTBI. Immunocal® significantly limited gliosis in these models; however, its neuroprotection was partially overwhelmed by repetitive injury. Treatments that modulate distinct aspects of TBI pathophysiology, used in combination with GSH precursors like Immunocal®, may show more protection in these repetitive TBI models.

Neuropathologic findings in a young woman 4 years following declaration of brain death: case analysis and literature review

Brain death (death by neurologic criteria) is declared in 2% of all in-hospital deaths in the United States. Published neuropathology studies of individuals maintained on cardiorespiratory support are generally decades old, and notably include only 3 cases with long intervals between brain and "somatic" death (68 days, 101 days, 20 years). Here, we share our observations in a young woman supported for nearly 4½ years following declaration of brain death after oropharyngeal surgery. While limited by tissue availability and condition, we found evidence of at least partial perfusion of the superficial cerebral and cerebellar cortices by external carotid and vertebral arteries (via meningeal and posterior pharyngeal branches), characterized by focal cellular reaction and organization. Dural venous sinuses had thrombosis and recanalization, as well as iron deposition. In nonperfused brain areas, tissue "mummification," akin to that seen in certain postmortem conditions, including macerated stillbirths and saponification (adipocere formation), was identified, and are reviewed herein. Unfortunately, correlation with years-earlier clinical and radiographic observations was not possible. Nevertheless, we feel that our careful neuropathologic inspection of this case expands the understanding of the spectrum of human brain tissue alterations possible in a very rarely seen set of conditions.

Therapeutic targeting of microglia mediated oxidative stress after neurotrauma

Inflammation is a primary component of the central nervous system injury response. Traumatic brain and spinal cord injury are characterized by a pronounced microglial response to damage, including alterations in microglial morphology and increased production of reactive oxygen species (ROS). The acute activity of microglia may be beneficial to recovery, but continued inflammation and ROS production is deleterious to the health and function of other cells. Microglial nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX), mitochondria, and changes in iron levels are three of the most common sources of ROS. All three play a significant role in post-traumatic brain and spinal cord injury ROS production and the resultant oxidative stress. This review will evaluate the current state of therapeutics used to target these avenues of microglia-mediated oxidative stress after injury and suggest avenues for future research.

Contusion concomitant with ischemia injury aggravates skeletal muscle necrosis and hinders muscle functional recovery

Contusion concomitant with ischemia injury to skeletal muscles is common in civilian and battlefield trauma. Despite their clinical importance, few experimental studies on these injuries are reported. The present study established a rat skeletal muscle contusion concomitant with ischemia injury model to identify skeletal muscle alterations compared with contusion injury or ischemia injury. Macroscopic and microscopic morphological evaluation showed that contusion concomitant with ischemia injury aggravated muscle edema and hematoxylin-eosin (HE) injury score at 24 h postinjury. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) levels, together with gastrocnemius muscle (GM) tumor necrosis factor-alpha (TNF-α) content elevated at 24 h postinjury too. During the 28-day follow-up, electrophysiological and contractile impairment was more severe in the contusion concomitant with ischemia injury group. In addition, contusion concomitant with ischemia injury decreased the percentage of larger (600-3000 μm²) fibers and increased the fibrotic area and collagen I proportion in the GM. Smaller proportions of Pax7⁺ and MyoD⁺ satellite cells (SCs) were observed in the contusion concomitant with ischemia injury group at 7 days postinjury. In conclusion, contusion concomitant with ischemia injury to skeletal muscle not only aggravates early muscle fiber necrosis but also hinders muscle functional recovery by impairing SC differentiation and exacerbating fibrosis during skeletal muscle repair.

Multiscale Mechanobiology in Brain Physiology and Diseases

Increasing evidence suggests that mechanics play a critical role in regulating brain function at different scales. Downstream integration of mechanical inputs into biochemical signals and genomic pathways causes observable and measurable effects on brain cell fate and can also lead to important pathological consequences. Despite recent advances, the mechanical forces that influence neuronal processes remain largely unexplored, and how endogenous mechanical forces are detected and transduced by brain cells into biochemical and genetic programs have received less attention. In this review, we described the composition of brain tissues and their pronounced microstructural heterogeneity. We discuss the individual role of neuronal and glial cell mechanics in brain homeostasis and diseases. We highlight how changes in the composition and mechanical properties of the extracellular matrix can modulate brain cell functions and describe key mechanisms of the mechanosensing process. We then consider the contribution of mechanobiology in the emergence of brain diseases by providing a critical review on traumatic brain injury, neurodegenerative diseases, and neuroblastoma. We show that a better understanding of the mechanobiology of brain tissues will require to manipulate the physico-chemical parameters of the cell microenvironment, and to develop three-dimensional models that can recapitulate the complexity and spatial diversity of brain tissues in a reproducible and predictable manner. Collectively, these emerging insights shed new light on the importance of mechanobiology and its implication in brain and nerve diseases.

Oxidative stress and regeneration

Regeneration is the process of replacing/restoring a damaged cell/tissue/organ to its full function and is limited respecting complexity of specific organ structures and the level of differentiation of the cells. Unlike physiological cell turnover, this tissue replacement form is activated upon pathological stimuli such as injury and/or disease that usually involves inflammatory response. To which extent will tissue repair itself depends on many factors and involves different mechanisms. Oxidative stress is one of them, either acute, as in case of traumatic brin injury or chronic, as in case of neurodegeneration, oxidative stress within brain involves lipid peroxidation, which generates reactive aldehydes, such as 4-hydroxynonenal (4-HNE). While 4-HNE is certainly neurotoxic and causes disruption of the blood brain barrier in case of severe injuries, it is also physiologically produced by glial cells, especially astrocytes, but its physiological roles within CNS are not understood. Because 4-HNE can regulate the response of the other cells in the body to stress, enhance their antioxidant capacities, proliferation and differentiation, we could assume that it may also have some beneficial role for neuroregeneration. Therefore, future studies on the relevance of 4-HNE for the interaction between neuronal cells, notably stem cells and reactive astrocytes might reveal novel options to better monitor and treat consequences or brain injuries, neurodegeneration and regeneration.

Mitochondrial Dysfunction in Rabies Virus-Infected Human and Canine Brains

Rabies is a fatal encephalitis caused by the Rabies lyssavirus (RABV). The presence of minimal neuropathological changes observed in rabies indicates that neuronal dysfunction, rather than neuronal death contributes to the fatal outcome. The role of mitochondrial changes has been suggested as a possible mechanism for neuronal dysfunction in rabies. However, these findings are mostly based on studies that have employed experimental models and laboratory-adapted virus. Studies on brain tissues from naturally infected human and animal hosts are lacking. The current study investigated the role of mitochondrial changes in rabies by morphological, biochemical and proteomic analysis of RABV-infected human and canine brains. Morphological analysis showed minimal inflammation with preserved neuronal and disrupted mitochondrial structure in both human and canine brains. Proteomic analysis revealed involvement of mitochondrial processes (oxidative phosphorylation, cristae formation, homeostasis and transport), synaptic proteins and autophagic pathways, with over-expression of subunits of mitochondrial respiratory complexes. Consistent with these findings, human and canine brains displayed elevated activities of complexes I (p < 0.05), IV (p < 0.05) and V (p < 0.05). However, this did not result in elevated ATP production (p < 0.0001), probably due to lowered mitochondrial membrane potential as noted in RABV-infected cells in culture. These could lead to mitochondrial dysfunction and mitophagy as indicated by expression of FKBP8 (p < 0.05) and PINK1 (p < 0.001)/PARKIN (p > 0.05) and ensuing autophagy, as shown by the status of LCIII (p < 0.05), LAMP1 (p < 0.001) and pertinent ultrastructural markers. We propose that altered mitochondrial bioenergetics and cristae architecture probably induce mitophagy, leading to autophagy and consequent neuronal dysfunction in rabies.

p66Shc-mediated oxidative stress is involved in gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a heightened level of oxidative stress, which is characterized by the overproduction of reactive oxygen species (ROS) from mitochondria. Previous studies showed that mitochondrial dysfunction is regulated by dynamin-related protein 1 (Drp1) and p66Shc in GDM.

AIM

The aim was to investigate the expression of Drp1 and p66Shc and their possible mechanisms in the pathogenesis of GDM.

METHODS

A total of 30 pregnant women, 15 with GDM and 15 without GDM, were enrolled. Peripheral blood mononuclear cells and placental tissue were collected. The human JEG3 trophoblast cell line was cultivated in 5.5 mmol/L or 30 mmol/L glucose and transfected with wild-type (wt)-p66Shc and p66Shc siRNA. P66Shc and Drp1 mRNA levels were detected by quantitative real-time polymerase chain reaction. The expression of p66Shc and Drp1 was assayed by immunohistochemistry and western blotting. ROS was assayed by dihydroethidium staining.

RESULTS

The p66Shc mRNA level was increased in the serum (P < 0.01) and placentas (P < 0.01) of women with GDM, and the expression of Drp1 mRNA and protein were also increased in placentas (P < 0.05). In JEG3 cells treated with 30 mmol/L glucose, the mRNA and protein expression of p66Shc and Drp1 were increased at 24 h (both P < 0.05), 48 h (both P < 0.01) and 72 h (both P < 0.001). ROS expression was also increased. High levels of Drp1 and ROS expression were detected in JEG3 cells transfected with wt-p66Shc (P < 0.01), and low levels were detected in JEG3 cells transfected with p66Shc siRNA (P < 0.05).

CONCLUSION

The upregulated expression of Drp1 and p66shc may contribute to the occurrence and development of GDM. Regulation of the mitochondrial fusion-fission balance could be a novel strategy for GDM treatment.

Inflammation in Traumatic Brain Injury

There is an increasing evidence that inflammation contributes to clinical and functional outcomes in traumatic brain injury (TBI). Many successful target-engaging, lesion-reducing, symptom-alleviating, and function-improving interventions in animal models of TBI have failed to show efficacy in clinical trials. Timing and immunological context are paramount for the direction, quality, and intensity of immune responses to TBI and the resulting neuroanatomical, clinical, and functional course. We present components of the immune system implicated in TBI, potential immune targets, and target-engaging interventions. The main objective of our article is to point toward modifiable molecular and cellular mechanisms that may modify the outcomes in TBI, and contribute to increasing the translational value of interventions that have been identified in animal models of TBI.

Fluid proteomics of CSF and serum reveal important neuroinflammatory proteins in blood-brain barrier disruption and outcome prediction following severe traumatic brain injury: a prospective, observational study

BACKGROUND

Severe traumatic brain injury (TBI) is associated with blood-brain barrier (BBB) disruption and a subsequent neuroinflammatory process. We aimed to perform a multiplex screening of brain enriched and inflammatory proteins in blood and cerebrospinal fluid (CSF) in order to study their role in BBB disruption, neuroinflammation and long-term functional outcome in TBI patients and healthy controls.

METHODS

We conducted a prospective, observational study on 90 severe TBI patients and 15 control subjects. Clinical outcome data, Glasgow Outcome Score, was collected after 6-12 months. We utilized a suspension bead antibody array analyzed on a FlexMap 3D Luminex platform to characterize 177 unique proteins in matched CSF and serum samples. In addition, we assessed BBB disruption using the CSF-serum albumin quotient (QA), and performed Apolipoprotein E-genotyping as the latter has been linked to BBB function in the absence of trauma. We employed pathway-, cluster-, and proportional odds regression analyses. Key findings were validated in blood samples from an independent TBI cohort.

RESULTS

TBI patients had an upregulation of structural CNS and neuroinflammatory pathways in both CSF and serum. In total, 114 proteins correlated with QA, among which the top-correlated proteins were complement proteins. A cluster analysis revealed protein levels to be strongly associated with BBB integrity, but not carriage of the Apolipoprotein E4-variant. Among cluster-derived proteins, innate immune pathways were upregulated. Forty unique proteins emanated as novel independent predictors of clinical outcome, that individually explained ~ 10% additional model variance. Among proteins significantly different between TBI patients with intact or disrupted BBB, complement C9 in CSF (p = 0.014, ΔR2 = 7.4%) and complement factor B in serum (p = 0.003, ΔR2 = 9.2%) were independent outcome predictors also following step-down modelling.

CONCLUSIONS

This represents the largest concomitant CSF and serum proteomic profiling study so far reported in TBI, providing substantial support to the notion that neuroinflammatory markers, including complement activation, predicts BBB disruption and long-term outcome. Individual proteins identified here could potentially serve to refine current biomarker modelling or represent novel treatment targets in severe TBI.

Involvement of Nrf-2/HO-1 pathway in sevoflurane-induced cognitive improvement in rats with traumatic brain injury

Traumatic brain injury (TBI) is an increasingly common emergency disease that usually leads to prolonged physical and cognitive impairments. In this study, we investigated if sevoflurane could induce cognitive improvement in TBI rats. Rats were subjected to head trauma induced by a fluid percussion device. A two-hour exposure to 3% sevoflurane was performed in a chamber immediately after TBI. Sevoflurane inhalation reduced the neurological and cognitive deficits induced by TBI with ameliorated synaptic injuries in the hippocampus. Moreover, after sevoflurane treatment, the expression of nuclear factor erythroid-2-related factor-2 (Nrf-2) and hemeoxygenase-1 (HO-1) in the hippocampus was enhanced 1 d after TBI and maintained at high levels 14 days later, and oxidative stress induced by TBI was inhibited. However, the HO-1 inhibitor, Zinc protoporphyrin (ZnPP), used to demonstrate the involvement of HO-1, suppressed the protective effect of sevoflurane. These results indicate that sevoflurane administered immediately after TBI may protect against TBI-induced synaptic and cognitive impairments by promoting the antioxidant Nrf-2/HO-1 pathway. Sevoflurane may be a promising anesthetic for patients with TBI.

The Significance of Mutation in IL-1β Gene and Circulatory Level for Prediction of Trauma Severity and Outcome in Traumatic Cerebral Hemorrhagic Contusion

BACKGROUND

Traumatic brain injuries (TBIs) is a leading cause of death, disability, and resources consumption. Cerebral hemorrhagic contusions are primary brain lesion and often one of the most visible lesions following TBIs. Interleukin-one beta (IL-1 β) is pro-inflammatory cytokines it is circulatory level and gene have been implicated in secondary brain injury and worse outcome following TBIs. This study is to determine the significance role of IL-1 β gene polymorphism (-511C/T) and circulatory level for prediction trauma severity and outcome in traumatic cerebral hemorrhagic contusion.

METHODS

The study population includes 90 Sudanese patients with traumatic cerebral hemorrhagic and 90 apparently healthy individuals as control. IL-1β serum concentration was measured using enzyme-linked immunosorbent assay and IL-1β gene was genotyped using restriction fragment length polymorphism-polymerase chain reaction.

RESULTS

Significant elevation of IL-1β level was seen among trauma patients compared to control (p-value < 0.001). Although there was no significant association between IL-1β level with trauma severity or death; IL-1β level was higher in severe brain injures compared with moderate and mild one, and the mean concentration of IL-1β was high (18.75 pg/mL) among patient developed poor outcome compared to survivals (15.17 pg/mL). T recessive allele of IL-1 β gene was detected in 13.3% of participant. The highest circulatory level of IL-1β (17.8 pg/mL) was observed among patients with TT homozygous alleles. IL-1 β gene polymorphism was not associated with trauma severity and death.

CONCLUSIONS

IL-1β circulatory level was varied according to trauma severity and highly levels were seen among patients developed unfavorable outcome. IL-1β -511C/T gene was not associated with trauma severity and outcome.

Paclitaxel Reduces Brain Injury from Repeated Head Trauma in Mice

Repetitive mild traumatic brain injury (rmTBI) is known to disturb axonal integrity and may play an important role in the pathogenic cascades leading to neurodegeneration. One critical approach to reduce the future onset of neurodegeneration is to intervene in this process at an early stage following a brain injury. Previously we showed that direct application of the microtubule-stabilizing drug, paclitaxel, on the brain following controlled cortical impact improved motor function and reduced lesion size. Herein, we extended these findings to a model of mild brain injury induced by repeated closed-skull impacts. Paclitaxel was administered intranasally to circumvent its poor transport across the blood-brain barrier. Mice received five mild closed-skull impacts (one per day for five days). Intranasal paclitaxel was administered once only, immediately after the first impact. We found that paclitaxel prevented injury-induced deficits in a spatial memory task in a water tread maze. In vivo magnetic resonance imaging (MRI) and positron emission tomography with 18F-flurodeoxyglucose (FDG-PET) revealed that paclitaxel prevented structural injury and hypometabolism. On MRI, apparent, injury-induced microbleeds were observed in 100% of vehicle-treated rmTBI mice, but not in paclitaxel-treated subjects. FDG-PET revealed a 42% increase in whole brain glucose metabolism in paclitaxel-treated mice as compared to vehicle-treated rmTBI. Immunohistochemistry found reduced evidence of axonal injury and synaptic loss. Our results indicate that intranasal paclitaxel administration imparts neuroprotection against brain injury and cognitive impairment in mice. The results from this study support the idea that microtubule-stabilization strategies hold therapeutic promise in mitigating traumatic brain injury.

The Attenuation of Traumatic Brain Injury via Inhibition of Oxidative Stress and Apoptosis by Tanshinone IIA

Traumatic brain injury (TBI) is a major source of mortality and long-term disability worldwide. The mechanisms associated with TBI development are poorly understood, and little progress has been made in the treatment of TBI. Tanshinone IIA is an effective agent to treat a variety of disorders; however, the mechanisms of Tanshinone IIA on TBI remain unclear. The aim of the present study was to investigate the therapeutic potential of Tanshinone IIA on TBI and its underlying molecular mechanisms. Changes in microvascular permeability were examined to determine the extent of TBI with Evans blue dye. Brain edema was assessed by measuring the wet weight to dry weight ratio. The expression levels of CD11, interleukin- (IL-) 1β, and tumor necrosis factor- (TNF-) α mRNA were determined by reverse transcription-quantitative PCR. Aquaporin-4 (AQP4), glial fibrillary acidic protein (GFAP), and p47phox protein expression levels were detected by western blotting. Superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-PX) activities, and malondialdehyde (MDA) content were determined using commercial kits. Cell apoptosis was detected by western blotting and TUNEL staining. Tanshinone IIA (10 mg/kg/day, intraperitoneal administration) significantly reduced brain water content and vascular permeability at 12, 24, 48, and 72 h after TBI. Tanshinone IIA downregulated the mRNA expression levels of various factors induced by TBI, including CD11, IL-1β, and TNF-α. Notably, CD11 mRNA downregulation suggested that Tanshinone IIA inhibited microglia activation. Further results showed that Tanshinone IIA treatment significantly downregulated AQP4 and GFAP expression. TBI-induced oxidative stress and apoptosis were markedly reversed by Tanshinone IIA, with an increase in SOD and GSH-PX activities and a decrease in the MDA content. Moreover, Tanshinone IIA decreased TBI-induced NADPH oxidase activation via the inhibition of p47phox. Tanshinone IIA attenuated TBI, and its mechanism of action may involve the inhibition of oxidative stress and apoptosis.

Unbiased Proteomic Approach Identifies Pathobiological Profiles in the Brains of Preclinical Models of Repetitive Mild Traumatic Brain Injury, Tauopathy, and Amyloidosis

No concerted investigation has been conducted to explore overlapping and distinct pathobiological mechanisms between repetitive mild traumatic brain injury (r-mTBI) and tau/amyloid proteinopathies considering the long history of association between TBI and Alzheimer’s disease. We address this problem by using unbiased proteomic approaches to generate detailed time-dependent brain molecular profiles of response to repetitive mTBI in C57BL/6 mice and in mouse models of amyloidosis (with amyloid precursor protein KM670/671NL (Swedish) and Presenilin 1 M146L mutations [PSAPP]) and tauopathy (hTau). Brain tissues from animals were collected at different timepoints after injuries (24 hr–12 months post-injury) and at different ages for tau or amyloid transgenic models (3, 9, and 15 months old), encompassing the pre-, peri-, and post-“onset” of cognitive and pathological phenotypes. We identified 30 hippocampal and 47 cortical proteins that were significantly modulated over time in the r-mTBI compared with sham mice. These proteins identified TBI-dependent modulation of phosphatidylinositol-3-kinase/AKT signaling, protein kinase A signaling, and PPARα/RXRα activation in the hippocampus and protein kinase A signaling, gonadotropin-releasing hormone signaling, and B cell receptor signaling in the cortex. Previously published neuropathological studies of our mTBI model showed a lack of amyloid and tau pathology. In PSAPP mice, we identified 19 proteins significantly changing in the cortex and only 7 proteins in hTau mice versus wild-type littermates. When we explored the overlap between our r-mTBI model and the PSAPP/hTau models, a fairly small coincidental change was observed involving only eight significantly regulated proteins. This work suggests a very distinct TBI neurodegeneration and also that other factors are needed to drive pathologies such as amyloidosis and tauopathy postinjury.

Dynamic features of brain edema in rat models of traumatic brain injury

We explored the dynamic features of brain edema after traumatic brain injury (TBI) using healthy adult male Wistar rats. After inducing moderate brain injuries in the rats, we divided them randomly among seven groups on the basis of the time elapsed between TBI and examination: 1, 6, 12, 24, 48, 72, and 168 h. All rats were scanned using diffusion-weighted imaging (DWI) to observe tissue changes in the contusion penumbra (CP) after TBI. Immunoglobulin G expression was also detected. At 1 h after TBI, there was an annular light-colored region in the CP where the intercellular space was enlarged, suggesting vasogenic edema. At 6 h, the cells expanded, their nuclei shrank, and the cytoplasm was replaced by vacuoles, indicating intracellular edema. Vasogenic edema and intracellular edema increased 12 h after TBI, but decreased 24 h after TBI, with vasogenic edema increasing 48 h after TBI. By 72 h after TBI, intracellular edema dominated until resolution of all edema by 168 h after TBI. DWI indicated that the relative apparent diffusion coefficient increased markedly at 1 h after TBI, but was reduced at 6 and 12 h after TBI. At 48 h, relative apparent diffusion coefficient increased gradually and then declined at 72 h. In rats, TBI-related changes include dynamic variations in intracellular and vasogenic edema severity. Routine MRI and DWI examinations do not distinguish between the center of trauma and CP; however, the apparent diffusion coefficient diagram can portray variations in CP edema type and degree at different time-points following TBI.

Application of the Zebrafish Traumatic Brain Injury Model in Assessing Cerebral Inflammation

Traumatic brain injury (TBI) is a major public and socioeconomic problem throughout the world. The establishment of an effective and cost-effective TBI model for developing new therapeutic agents is challenging. Microglia are considered the resident macrophages of the central nervous system (CNS) that normally do not enter the brain. As the primary mediators of the innate immune response in the CNS, microglia play a critical role in neuroinflammation and secondary injury after TBI. In this study, we established an in vivo TBI zebrafish model using Tg(coro1a:EGFP) line where the green fluorescent protein-labeled microglia were present. We demonstrated that microglia accumulated rapidly in response to neuronal injuries. To clear away injured neurons and restore the CNS homeostasis, activated microglia secreted two types of functional cytokines, including pro-inflammatory interleukins (IL) of IL-1β and IL-6 and anti-inflammatory factors of IL-4 and IL-10 in the lesioned larvae. Cytidine 5'-Diphosphocholine (CDP-choline), as an effective and clinical neuroprotective drug, could further activate microglia, expressing high levels of il-1β, il-6, il-4, and il-10 in the TBI model. Moreover, CDP-choline reduced neuronal apoptosis and promoted neuronal proliferation around the lesioned site. Based on these results, the TBI model established in this study represents a suitable model for developing new therapeutic agents for CNS-associated diseases.

Defining New Research Questions and Protocols in the Field of Traumatic Brain Injury through Public Engagement: Preliminary Results and Review of the Literature

Traumatic brain injury (TBI) is the most common cause of death and disability in the age group below 40 years. The financial cost of loss of earnings and medical care presents a massive burden to family, society, social care, and healthcare, the cost of which is estimated at £1 billion per annum (about brain injury (online)). At present, we still lack a full understanding on the pathophysiology of TBI, and biomarkers represent the next frontier of breakthrough discoveries. Unfortunately, many tenets limit their widespread adoption. Brain tissue sampling is the mainstay of diagnosis in neuro-oncology; following on this path, we hypothesise that information gleaned from neural tissue samples obtained in TBI patients upon hospital admission may correlate with outcome data in TBI patients, enabling an early, accurate, and more comprehensive pathological classification, with the intent of guiding treatment and future research. We proposed various methods of tissue sampling at opportunistic times: two methods rely on a dedicated sample being taken; the remainder relies on tissue that would otherwise be discarded. To gauge acceptance of this, and as per the guidelines set out by the National Research Ethics Service, we conducted a survey of TBI and non-TBI patients admitted to our Trauma ward and their families. 100 responses were collected between December 2017 and July 2018, incorporating two redesigns in response to patient feedback. 75.0% of respondents said that they would consent to a brain biopsy performed at the time of insertion of an intracranial pressure (ICP) bolt. 7.0% replied negatively and 18.0% did not know. 70.0% would consent to insertion of a jugular bulb catheter to obtain paired intracranial venous samples and peripheral samples for analysis of biomarkers. Over 94.0% would consent to neural tissue from ICP probes, external ventricular drains (EVD), and lumbar drains (LD) to be salvaged, and 95.0% would consent to intraoperative samples for further analysis.

Predictive Value of Leakage Signs for Pure Brain Contusional Hematoma Expansion

Hematoma expansion is an important consideration in patients with traumatic brain injury (TBI). No precise methods are available, however, for predicting the expansion of TBI-related hematoma. We aimed to establish a more sensitive predictor for contusional hematoma expansion based on the presence of leakage signs on computed tomography angiography (CTA). Thirty-three patients with pure contusion were included in the analysis (age: 64.1 ± 20.6 years; 24 men and 7 women). We compared Hounsfield unit (HU) values within set regions of interest (diameter, 10 mm) between serial CTA phase and delayed-phase CT images (5 min after CTA phase). Positive leakage signs were defined as >10% increases in HU value. Hematoma expansion was determined using plain CT at 24 h in patients who did not undergo emergent surgery. Glasgow Coma Scale (GCS) scores measured at admission and 24 h after admission were also compared. Leakage signs predicted hematoma expansion with high specificity (100%) and sensitivity (92.8%). Patients with positive leakage signs had significant decreases in GCS scores 24 h after the scan (GCS change: positive group, -0.92 ± 0.59; negative group, 1.14 ± 0.82). Positive leakage signs were clearly associated with surgical hematoma removal. Five patients without hematoma who had positive leakage signs at admission exhibited significant expansion of hematomas 24 h later. Our results indicate that leakage signs had high sensitivity in the prediction of contusional hematoma expansion and were significantly associated with delayed neurological deterioration and the necessity of surgical removal.

Mammalian Models of Traumatic Brain Injury and a Place for Drosophila in TBI Research

Traumatic brain injury (TBI), caused by a sudden blow or jolt to the brain that disrupts normal function, is an emerging health epidemic with ∼2.5 million cases occurring annually in the United States that are severe enough to cause hospitalization or death. Most common causes of TBI include contact sports, vehicle crashes and domestic violence or war injuries. Injury to the central nervous system is one of the most consistent candidates for initiating the molecular and cellular cascades that result in Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS). Not every TBI event is alike with effects varying from person to person. The majority of people recover from mild TBI within a short period of time, but repeated incidents can have deleterious long-lasting effects which depend on factors such as the number of TBIs sustained, time till medical attention, age, gender and genetics of the individual. Despite extensive research, many questions still remain regarding diagnosis, treatment, and prevention of long-term effects from TBI as well as recovery of brain function. In this review, we present an overview of TBI pathology, discuss mammalian models for TBI and focus on current methods using Drosophila melanogaster as a model for TBI study. The relatively small brain size (∼100,000 neurons and glia), conserved neurotransmitter signaling mechanisms and sophisticated genetics of Drosophila allows for cell biological, molecular and genetic analyses that are impractical in mammalian models of TBI.

Serum Amyloid A Protein as a Potential Biomarker for Severity and Acute Outcome in Traumatic Brain Injury

Traumatic brain injury (TBI) causes a wide variety of neuroinflammatory events. These neuroinflammatory events depend, to a greater extent, on the severity of the damage. Our previous studies have shown that the liver produces serum amyloid A (SAA) at high levels in the initial hours after controlled cortical impact (CCI) injury in mice. Clinical studies have reported detectable SAA in the plasma of brain injury patients, but it is not clear if SAA levels depend on TBI severity. To evaluate this question, we performed a mild to severe CCI injury in wild-type mice. We collected blood samples and brains at 1, 3, and 7 days after injury for protein detection by western blotting, enzyme-linked immunosorbent assay, or immunohistochemical analysis. Our results showed that severe CCI injury compared to mild CCI injury or sham mice caused an increased neuronal death, larger lesion volume, increased microglia/macrophage density, and augmented neutrophil infiltration. Furthermore, we found that the serum levels of SAA protein ascended in the blood in correlation with high neuroinflammatory and neurodegenerative responses. Altogether, these results suggest that serum SAA may be a novel neuroinflammation-based, and severity-dependent, biomarker for acute TBI.

Proteomic Analysis of the Human Anterior Pituitary Gland

The pituitary function is regulated by a complex system involving the hypothalamus and biological networks within the pituitary. Although the hormones secreted from the pituitary have been well studied, comprehensive analyses of the pituitary proteome are limited. Pituitary proteomics is a field of postgenomic research that is crucial to understand human health and pituitary diseases. In this context, we report here a systematic proteomic profiling of human anterior pituitary gland (adenohypophysis) using high-resolution Fourier transform mass spectrometry. A total of 2164 proteins were identified in this study, of which 105 proteins were identified for the first time compared with high-throughput proteomic-based studies from human pituitary glands. In addition, we identified 480 proteins with secretory potential and 187 N-terminally acetylated proteins. These are the first region-specific data that could serve as a vital resource for further investigations on the physiological role of the human anterior pituitary glands and the proteins secreted by them. We anticipate that the identification of previously unknown proteins in the present study will accelerate biomedical research to decipher their role in functioning of the human anterior pituitary gland and associated human diseases.

Enduring Neuroprotective Effect of Subacute Neural Stem Cell Transplantation After Penetrating TBI

Traumatic brain injury (TBI) is the largest cause of death and disability of persons under 45 years old, worldwide. Independent of the distribution, outcomes such as disability are associated with huge societal costs. The heterogeneity of TBI and its complicated biological response have helped clarify the limitations of current pharmacological approaches to TBI management. Five decades of effort have made some strides in reducing TBI mortality but little progress has been made to mitigate TBI-induced disability. Lessons learned from the failure of numerous randomized clinical trials and the inability to scale up results from single center clinical trials with neuroprotective agents led to the formation of organizations such as the Neurological Emergencies Treatment Trials (NETT) Network, and international collaborative comparative effectiveness research (CER) to re-orient TBI clinical research. With initiatives such as TRACK-TBI, generating rich and comprehensive human datasets with demographic, clinical, genomic, proteomic, imaging, and detailed outcome data across multiple time points has become the focus of the field in the United States (US). In addition, government institutions such as the US Department of Defense are investing in groups such as Operation Brain Trauma Therapy (OBTT), a multicenter, pre-clinical drug-screening consortium to address the barriers in translation. The consensus from such efforts including “The Lancet Neurology Commission” and current literature is that unmitigated cell death processes, incomplete debris clearance, aberrant neurotoxic immune, and glia cell response induce progressive tissue loss and spatiotemporal magnification of primary TBI. Our analysis suggests that the focus of neuroprotection research needs to shift from protecting dying and injured neurons at acute time points to modulating the aberrant glial response in sub-acute and chronic time points. One unexpected agent with neuroprotective properties that shows promise is transplantation of neural stem cells. In this review we present (i) a short survey of TBI epidemiology and summary of current care, (ii) findings of past neuroprotective clinical trials and possible reasons for failure based upon insights from human and preclinical TBI pathophysiology studies, including our group's inflammation-centered approach, (iii) the unmet need of TBI and unproven treatments and lastly, (iv) present evidence to support the rationale for sub-acute neural stem cell therapy to mediate enduring neuroprotection.

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.

Lateral cerebellar nucleus stimulation promotes motor recovery and suppresses neuroinflammation in a fluid percussion injury rodent model

BACKGROUND

Many traumatic brain injury (TBI) survivors live with persistent disability from chronic motor deficits despite contemporary rehabilitation services, underscoring the need for novel treatment.

OBJECTIVE/HYPOTHESIS

We have previously shown that deep brain stimulation (DBS) of the lateral cerebellar nucleus (LCN) can enhance post-stroke motor recovery and increase the expression of markers of long-term potentiation in perilesional cerebral cortex. We hypothesize that a similar beneficial effect will be for motor deficits induced by unilateral fluid percussion injury (FPI) in rodents through long-term potentiation- and anti-inflammatory based mechanisms.

METHODS

Male Long Evans rats with a DBS macroelectrode in the LCN underwent FPI over contralateral primary motor cortex. After 4 weeks of spontaneous recovery, DBS treatment was applied for 4 weeks, with the pasta matrix, cylinder, and horizontal ladder tests used to evaluate motor performance. All animals were euthanized and tissue harvested for further analysis by histology, immunohistochemistry, RNA microarray assay and Western Blot.

RESULTS

LCN DBS-treated animals experienced a significantly greater rate of motor recovery than untreated surgical controls, with treated animals showing enhanced expression of RNA and protein for excitability related genes, suppressed expression of pro-inflammatory genes, suppressed microglial and astrocytic activation, but proliferation of c-fos positive cells. Finally, our data suggest a possible role for anti-apoptotic effects with LCN DBS.

CONCLUSION

LCN DBS enhanced the motor recovery following TBI, possibly by elevating the neuronal excitability at the perilesional area and mediating anti-apoptotic and anti-inflammatory effects.

Prognostic utility of circulating nucleic acids in acute brain injuries

INTRODUCTION

Acute brain injuries represent major causes of morbidity and mortality worldwide. Nevertheless, therapeutic options are centered mainly on supportive care, and accurate prognosis prediction following traumatic brain injury (TBI) or stroke remains a challenge in clinical settings. Areas covered: Circulating DNA and RNA have shown potential as predictive molecules in acute brain injuries. In particular, plasma cell-free DNA (cfDNA) levels have been correlated to severity, mortality, and outcome after TBI and stroke. The real-time quantitative polymerase chain reaction (qPCR) is the most widely used technique for determination of cfDNA in brain injuries; however, to consider the use of cfDNA in emergency settings, a quicker and easier methodology for detection should be established. A recent study proposed detection of cfDNA applying a rapid fluorescent test that showed compatible results with qPCR. Expert commentary: As a promising perspective, detection of cfDNA levels using simple, rapid, and cheap methodology has potential to translate to clinic as a point-of-care marker, supporting the clinical decision-making in emergency care settings. Conversely, miRNA profiles may be used as signatures to determine the type and severity of injuries. Additionally, in the future, some miRNAs may constitute innovative neurorestorative therapies without the common hurdles associated with cell therapy.

Brain Phospholipid Precursors Administered Post-Injury Reduce Tissue Damage and Improve Neurological Outcome in Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) leads to cellular loss, destabilization of membranes, disruption of synapses and altered brain connectivity, and increased risk of neurodegenerative disease. A significant and long-lasting decrease in phospholipids (PLs), essential membrane constituents, has recently been reported in plasma and brain tissue, in human and experimental TBI. We hypothesized that supporting PL synthesis post-injury could improve outcome post-TBI. We tested this hypothesis using a multi-nutrient combination designed to support the biosynthesis of PLs and available for clinical use. The multi-nutrient, Fortasyn^® Connect (FC), contains polyunsaturated omega-3 fatty acids, choline, uridine, vitamins, cofactors required for PL biosynthesis, and has been shown to have significant beneficial effects in early Alzheimer's disease. Male C57BL/6 mice received a controlled cortical impact injury and then were fed a control diet or a diet enriched with FC for 70 days. FC led to a significantly improved sensorimotor outcome and cognition, reduced lesion size and oligodendrocyte loss, and it restored myelin. It reversed the loss of the synaptic protein synaptophysin and decreased levels of the axon growth inhibitor, Nogo-A, thus creating a permissive environment. It decreased microglia activation and the rise in ß-amyloid precursor protein and restored the depressed neurogenesis. The effects of this medical multi-nutrient suggest that support of PL biosynthesis post-TBI, a new treatment paradigm, has significant therapeutic potential in this neurological condition for which there is no satisfactory treatment. The multi-nutrient tested has been used in dementia patients and is safe and well tolerated, which would enable rapid clinical exploration in TBI.

Jia-Jian-Di-Huang-Yin-Zi decoction exerts neuroprotective effects on dopaminergic neurons and their microenvironment

As a classical prescription of Traditional Chinese medicine, the Jia-Jian-Di-Huang-Yin-Zi (JJDHYZ) decoction has long been used to treat movement disorders. The present study evaluated the effects of JJDHYZ on dopaminergic (DA) neurons and their survival-enhancing microenvironment as well as the possible mechanisms involved using a mouse model of Parkinson's disease. In MPTP-lesioned mice, a high dosage of JJDHYZ (34 g/kg/day) attenuated the loss of DA neurons, reversed the dopamine depletion, and improved the expression of glial-derived neurotrophic factor (GDNF) compared to the untreated model group. JJDHYZ also protected the ultrastructure of the blood-brain barrier (BBB) and tight junction proteins by inhibiting the activation of microglia and astrocytes besides the increase in three types of matrix metalloproteinases in the substantia nigra. In conclusion, the JJDHYZ-high dosage (JJDHYZ-H) group exhibited the neuroprotection of DA neurons, and the underlying mechanism may be related to the survival-enhancing microenvironment of the DA neurons.

Proteomic differences between focal and diffuse traumatic brain injury in human brain tissue

The early molecular response to severe traumatic brain injury (TBI) was evaluated using biopsies of structurally normal-appearing cortex, obtained at location for intracranial pressure (ICP) monitoring, from 16 severe TBI patients. Mass spectrometry (MS; label free and stable isotope dimethyl labeling) quantitation proteomics showed a strikingly different molecular pattern in TBI in comparison to cortical biopsies from 11 idiopathic normal pressure hydrocephalus patients. Diffuse TBI showed increased expression of peptides related to neurodegeneration (Tau and Fascin, p < 0.05), reduced expression related to antioxidant defense (Glutathione S-transferase Mu 3, Peroxiredoxin-6, Thioredoxin-dependent peroxide reductase; p < 0.05) and increased expression of potential biomarkers (e.g. Neurogranin, Fatty acid-binding protein, heart p < 0.05) compared to focal TBI. Proteomics of human brain biopsies displayed considerable molecular heterogeneity among the different TBI subtypes with consequences for the pathophysiology and development of targeted treatments for TBI.

Post-Translational Oxidative Modifications of Mitochondrial Complex I (NADH: Ubiquinone Oxidoreductase): Implications for Pathogenesis and Therapeutics in Human Diseases

Mitochondrial complex I (NADH: ubiquinone oxidoreductase; CI) is central to the electron transport chain (ETC), oxidative phosphorylation, and ATP production in eukaryotes. CI is a multi-subunit complex with a complicated yet organized structure that optimally connects electron transfer with proton translocation and forms higher-order supercomplexes with other ETC complexes. Efforts to understand the molecular genetics, expression profile of subunits, and structure-function relationship of CI have increased over the years due to the direct role of the complex in human diseases. Although mutations in the nuclear and mitochondrial genes of CI and altered expression of subunits could potentially lower CI activity leading to mitochondrial dysfunction in many diseases, oxidative post-translational modifications (PTMs) have emerged as an important mechanism contributing to altered CI activity. These mainly include reversible and irreversible cysteine modifications, tyrosine nitration, carbonylation, and tryptophan oxidation that are generated following exposure to reactive oxygen species/reactive nitrogen species. Interestingly, oxidative PTMs could contribute either to CI damage, mitochondrial dysfunction, and ensuing cell death or a response mechanism with potential cytoprotective effects. This has also emerged as a promising field for structural biologists since analysis of PTMs could assist in understanding the structure-function relationship of the complex and correlate electron transfer mechanism with energy production. However, analysis of PTMs of CI and their contribution to CI function are incomplete in many physiological and pathological conditions. This review aims to highlight the role of oxidative PTMs in modulating CI activity with implications toward pathobiology of CNS diseases and novel therapeutics.

Influence of white matter injury on gray matter reactive gliosis upon stab wound in the adult murine cerebral cortex

Traumatic brain injury frequently affects the cerebral cortex, yet little is known about the differential effects that occur if only the gray matter (GM) is damaged or if the injury also involves the white matter (WM). To tackle this important question and directly compare similarities and differences in reactive gliosis, we performed stab wound injury affecting GM and WM (GM+) and one restricted to the GM (GM-) in the adult murine cerebral cortex. First, we examined glial reactivity in the regions affected (WM and GM) and determined the influence of WM injury on reactive gliosis in the GM comparing the same area in the two injury paradigms. In the GM+ injury microglia proliferation is increased in the WM compared with GM, while proliferating astrocytes are more abundant in the GM than in the WM. Interestingly, WM lesion exerted a strong influence on the proliferation of the GM glial cells that was most pronounced at early stages, 3 days post lesion. While astrocyte proliferation was increased, NG2 glia proliferation was decreased in the GM+ compared with GM- lesion condition. Importantly, these differences were not observed when a lesion of the same size affected only the GM. Unbiased proteomic analyses further corroborate our findings in support of a profound difference in GM reactivity when WM is also injured and revealed MIF as a key regulator of NG2 glia proliferation.

Juvenile Traumatic Brain Injury Results in Cognitive Deficits Associated with Impaired Endoplasmic Reticulum Stress and Early Tauopathy

The leading cause of death in the juvenile population is trauma, and in particular neurotrauma. The juvenile brain response to neurotrauma is not completely understood. Endoplasmic reticulum (ER) stress has been shown to contribute to injury expansion and behavioral deficits in adult rodents and furthermore has been seen in adult postmortem human brains diagnosed with chronic traumatic encephalopathy. Whether endoplasmic reticulum stress is increased in juveniles with traumatic brain injury (TBI) is poorly delineated. We investigated this important topic using a juvenile rat controlled cortical impact (CCI) model. We proposed that ER stress would be significantly increased in juvenile rats following TBI and that this would correlate with behavioral deficits using a juvenile rat model. A juvenile rat (postnatal day 28) CCI model was used. Binding immunoglobulin protein (BiP) and C/EBP homologous protein (CHOP) were measured at 4 h in the ipsilateral pericontusion cortex. Hypoxia-inducible factor (HIF)-1α was measured at 48 h and tau kinase measured at 1 week and 30 days. At 4 h following injury, BiP and CHOP (markers of ER stress) were significantly elevated in rats exposed to TBI. We also found that HIF-1α was significantly upregulated 48 h following TBI showing delayed hypoxia. The early ER stress activation was additionally asso-ciated with the activation of a known tau kinase, glycogen synthase kinase-3β (GSK-3β), by 1 week. Tau oligomers measured by R23 were significantly increased by 30 days following TBI. The biochemical changes following TBI were associated with increased impulsive-like or anti-anxiety behavior measured with the elevated plus maze, deficits in short-term memory measured with novel object recognition, and deficits in spatial memory measured with the Morris water maze in juvenile rats exposed to TBI. These results show that ER stress was increased early in juvenile rats exposed to TBI, that these rats developed tau oligomers over the course of 30 days, and that they had significant short-term and spatial memory deficits following injury.

Erythropoietin and mTOR: A "One-Two Punch" for Aging-Related Disorders Accompanied by Enhanced Life Expectancy

Life expectancy continues to increase throughout the world, but is accompanied by a rise in the incidence of non-communicable diseases. As a result, the benefits of an increased lifespan can be limited by aging-related disorders that necessitate new directives for the development of effective and safe treatment modalities. With this objective, the mechanistic target of rapamycin (mTOR), a 289-kDa serine/threonine protein, and its related pathways of mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), proline rich Akt substrate 40 kDa (PRAS40), AMP activated protein kinase (AMPK), Wnt signaling, and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), have generated significant excitement for furthering novel therapies applicable to multiple systems of the body. Yet, the biological and clinical outcome of these pathways can be complex especially with oversight of cell death mechanisms that involve apoptosis and autophagy. Growth factors, and in particular erythropoietin (EPO), are one avenue under consideration to implement control over cell death pathways since EPO can offer potential treatment for multiple disease entities and is intimately dependent upon mTOR signaling. In experimental and clinical studies, EPO appears to have significant efficacy in treating several disorders including those involving the developing brain. However, in mature populations that are affected by aging-related disorders, the direction for the use of EPO to treat clinical disease is less clear that may be dependent upon a number of factors including the understanding of mTOR signaling. Continued focus upon the regulatory elements that control EPO and mTOR signaling could generate critical insights for targeting a broad range of clinical maladies.

Current and Emerging Technologies for Probing Molecular Signatures of Traumatic Brain Injury

Traumatic brain injury (TBI) is understood as an interplay between the initial injury, subsequent secondary injuries, and a complex host response all of which are highly heterogeneous. An understanding of the underlying biology suggests a number of windows where mechanistically inspired interventions could be targeted. Unfortunately, biologically plausible therapies have to-date failed to translate into clinical practice. While a number of stereotypical pathways are now understood to be involved, current clinical characterization is too crude for it to be possible to characterize the biological phenotype in a truly mechanistically meaningful way. In this review, we examine current and emerging technologies for fuller biochemical characterization by the simultaneous measurement of multiple, diverse biomarkers. We describe how clinically available techniques such as cerebral microdialysis can be leveraged to give mechanistic insights into TBI pathobiology and how multiplex proteomic and metabolomic techniques can give a more complete description of the underlying biology. We also describe spatially resolved label-free multiplex techniques capable of probing structural differences in chemical signatures. Finally, we touch on the bioinformatics challenges that result from the acquisition of such large amounts of chemical data in the search for a more mechanistically complete description of the TBI phenotype.

Monitoring the Neuroinflammatory Response Following Acute Brain Injury

Traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) are major contributors to morbidity and mortality. Following the initial insult, patients may deteriorate due to secondary brain damage. The underlying molecular and cellular cascades incorporate components of the innate immune system. There are different approaches to assess and monitor cerebral inflammation in the neuro intensive care unit. The aim of this narrative review is to describe techniques to monitor inflammatory activity in patients with TBI and SAH in the acute setting. The analysis of pro- and anti-inflammatory cytokines in compartments of the central nervous system (CNS), including the cerebrospinal fluid and the extracellular fluid, represent the most common approaches to monitor surrogate markers of cerebral inflammatory activity. Each of these compartments has a distinct biology that reflects local processes and the cross-talk between systemic and CNS inflammation. Cytokines have been correlated to outcomes as well as ongoing, secondary injury progression. Alongside the dynamic, focal assay of humoral mediators, imaging, through positron emission tomography, can provide a global in vivo measurement of inflammatory cell activity, which reveals long-lasting processes following the initial injury. Compared to the innate immune system activated acutely after brain injury, the adaptive immune system is likely to play a greater role in the chronic phase as evidenced by T-cell-mediated autoreactivity toward brain-specific proteins. The most difficult aspect of assessing neuroinflammation is to determine whether the processes monitored are harmful or beneficial to the brain as accumulating data indicate a dual role for these inflammatory cascades following injury. In summary, the inflammatory component of the complex injury cascade following brain injury may be monitored using different modalities. Using a multimodal monitoring approach can potentially aid in the development of therapeutics targeting different aspects of the inflammatory cascade and improve the outcome following TBI and SAH.

Spatiotemporal control of mitochondrial network dynamics in astroglial cells

Mitochondria are increasingly recognized for playing important roles in regulating the evolving metabolic state of mammalian cells. This is particularly true for nerve cells, as dysregulation of mitochondrial dynamics is invariably associated with a number of neuropathies. Accumulating evidence now reveals that changes in mitochondrial dynamics and structure may play equally important roles also in the cell biology of astroglial cells. Astroglial cells display significant heterogeneity in their morphology and specialized functions across different brain regions, however besides fundamental differences they seem to share a surprisingly complex meshwork of mitochondria, which is highly suggestive of tightly regulated mechanisms that contribute to maintain this unique architecture. Here, we summarize recent work performed in astrocytes in situ indicating that this may indeed be the case, with astrocytic mitochondrial networks shown to experience rapid dynamic changes in response to defined external cues. Although the mechanisms underlying this degree of mitochondrial re-shaping are far from being understood, recent data suggest that they may contribute to demarcate astrocyte territories undergoing key signalling and metabolic functions.

Neurotrauma: The Crosstalk between Neurotrophins and Inflammation in the Acutely Injured Brain

Traumatic brain injury (TBI) is a major cause of morbidity and mortality among young individuals worldwide. Understanding the pathophysiology of neurotrauma is crucial for the development of more effective therapeutic strategies. After the trauma occurs, immediate neurologic damage is produced by the traumatic forces; this primary injury triggers a secondary wave of biochemical cascades together with metabolic and cellular changes, called secondary neural injury. In the scenario of the acutely injured brain, the ongoing secondary injury results in ischemia and edema culminating in an uncontrollable increase in intracranial pressure. These areas of secondary injury progression, or areas of “traumatic penumbra”, represent crucial targets for therapeutic interventions. Neurotrophins are a class of signaling molecules that promote survival and/or maintenance of neurons. They also stimulate axonal growth, synaptic plasticity, and neurotransmitter synthesis and release. Therefore, this review focuses on the role of neurotrophins in the acute post-injury response. Here, we discuss possible endogenous neuroprotective mechanisms of neurotrophins in the prevailing environment surrounding the injured areas, and highlight the crosstalk between neurotrophins and inflammation with focus on neurovascular unit cells, particularly pericytes. The perspective is that neurotrophins may represent promising targets for research on neuroprotective and neurorestorative processes in the short-term following TBI.

Central Nervous System Injury and Nicotinamide Adenine Dinucleotide Phosphate Oxidase: Oxidative Stress and Therapeutic Targets

Injury to the central nervous system (CNS) includes both traumatic brain and spinal cord injury (TBI and SCI, respectively). These injuries, which are heterogeneous and, therefore, difficult to treat, result in long-lasting functional, cognitive, and behavioral deficits. Severity of injury is determined by multiple factors, and is largely mediated by the activity of the CNS inflammatory system, including the primary CNS immune cells, microglia. The nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) family of enzymes is a primary source of reactive oxygen species (ROS), key inflammatory mediators after CNS injury. ROS play a central role in inflammation, contributing to cytokine translation and release, microglial polarization and activation, and clearance of damaged tissue. NOX has been suggested as a potential therapeutic target in CNS trauma, as inhibition of this enzyme family modulates inflammatory cell response and ROS production. The purpose of this review is to understand how the different NOX enzymes function and what role they play in the scope of CNS trauma.

Degradomics in Neurotrauma: Profiling Traumatic Brain Injury

Degradomics has recently emerged as a subdiscipline in the omics era with a focus on characterizing signature breakdown products implicated in various disease processes. Driven by promising experimental findings in cancer, neuroscience, and metabolomic disorders, degradomics has significantly promoted the notion of disease-specific "degradome." A degradome arises from the activation of several proteases that target specific substrates and generate signature protein fragments. Several proteases such as calpains, caspases, cathepsins, and matrix metalloproteinases (MMPs) are involved in the pathogenesis of numerous diseases that disturb the physiologic balance between protein synthesis and protein degradation. While regulated proteolytic activities are needed for development, growth, and regeneration, uncontrolled proteolysis initiated under pathological conditions ultimately culminates into apoptotic and necrotic processes. In this chapter, we aim to review the protease-substrate repertoires in neural injury concentrating on traumatic brain injury. A striking diversity of protease substrates, essential for neuronal and brain structural and functional integrity, namely, encryptic biomarker neoproteins, have been characterized in brain injury. These include cytoskeletal proteins, transcription factors, cell cycle regulatory proteins, synaptic proteins, and cell junction proteins. As these substrates are subject to proteolytic fragmentation, they are ceaselessly exposed to activated proteases. Characterization of these molecules allows for a surge of "possible" therapeutic approaches of intervention at various levels of the proteolytic cascade.

Posttraumatic administration of a sub-anesthetic dose of ketamine exerts neuroprotection via attenuating inflammation and autophagy

As a complex disease, traumatic brain injury (TBI) can result in long-term psychiatric changes and sensorimotor and cognitive impairments. The TBI-induced loss of memory and long-term cognitive dysfunction are related to mechanistic factors including an increased inflammatory response, autophagy, edema, and ischemia. Many published studies have offered evidence for the neuroprotective effects and anti-inflammatory properties of ketamine for TBI patients. Nonetheless, there is a limited understanding of the accurate mechanism that underlies the potential neuroprotective effects of ketamine. Herein, it can be shown that posttraumatic administration of ketamine at a sub-anesthetic dose (10mg/kg ketamine, every 24h up to 7days) can prevent the TBI-induced production of IL-6 and TNF-α, attenuate deficits of dendrites and spines and exert beneficial effects on memory and behavior. Moreover, studies show that ketamine may activate the mTOR signaling pathway by p-mTOR induction to down-regulate the expression of crucial autophagic proteins such as LC3 and Beclin-1. According to these findings, ameliorating secondary brain injury and anti-inflammatory properties is closely related to the neuroprotection of ketamine, which supports the use of ketamine as a potential therapy for patients with TBI to alleviate functional deficits.

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.

Mapping the Connectome Following Traumatic Brain Injury

There is a paucity of accurate and reliable biomarkers to detect traumatic brain injury, grade its severity, and model post-traumatic brain injury (TBI) recovery. This gap could be addressed via advances in brain mapping which define injury signatures and enable tracking of post-injury trajectories at the individual level. Mapping of molecular and anatomical changes and of modifications in functional activation supports the conceptual paradigm of TBI as a disorder of large-scale neural connectivity. Imaging approaches with particular relevance are magnetic resonance techniques (diffusion weighted imaging, diffusion tensor imaging, susceptibility weighted imaging, magnetic resonance spectroscopy, functional magnetic resonance imaging, and positron emission tomographic methods including molecular neuroimaging). Inferences from mapping represent unique endophenotypes which have the potential to transform classification and treatment of patients with TBI. Limitations of these methods, as well as future research directions, are highlighted.

Endoplasmic reticulum stress-induced apoptosis in the penumbra aggravates secondary damage in rats with traumatic brain injury

Neuronal apoptosis is mediated by intrinsic and extrinsic signaling pathways such as the membrane-mediated, mitochondrial, and endoplasmic reticulum stress pathways. Few studies have examined the endoplasmic reticulum-mediated apoptosis pathway in the penumbra after traumatic brain injury, and it remains unclear whether endoplasmic reticulum stress can activate the caspase-12-dependent apoptotic pathway in the traumatic penumbra. Here, we established rat models of fluid percussion-induced traumatic brain injury and found that protein expression of caspase-12, caspase-3 and the endoplasmic reticulum stress marker 78 kDa glucose-regulated protein increased in the traumatic penumbra 6 hours after injury and peaked at 24 hours. Furthermore, numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells in the traumatic penumbra also reached peak levels 24 hours after injury. These findings suggest that caspase-12-mediated endoplasmic reticulum-related apoptosis is activated in the traumatic penumbra, and may play an important role in the pathophysiology of secondary brain injury.