Erythropoietin is neuroprotective, improves functional recovery, and reduces neuronal apoptosis and inflammation in a rodent model of experimental closed head injury

Neuroprotective therapies in the NICU in preterm infants: present and future (Neonatal Neurocritical Care Series)

The survival of preterm infants has steadily improved thanks to advances in perinatal and neonatal intensive clinical care. The focus is now on finding ways to improve morbidities, especially neurological outcomes. Although antenatal steroids and magnesium for preterm infants have become routine therapies, studies have mainly demonstrated short-term benefits for antenatal steroid therapy but limited evidence for impact on long-term neurodevelopmental outcomes. Further advances in neuroprotective and neurorestorative therapies, improved neuromonitoring modalities to optimize recruitment in trials, and improved biomarkers to assess the response to treatment are essential. Among the most promising agents, multipotential stem cells, immunomodulation, and anti-inflammatory therapies can improve neural outcomes in preclinical studies and are the subject of considerable ongoing research. In the meantime, bundles of care protecting and nurturing the brain in the neonatal intensive care unit and beyond should be widely implemented in an effort to limit injury and promote neuroplasticity. IMPACT: With improved survival of preterm infants due to improved antenatal and neonatal care, our focus must now be to improve long-term neurological and neurodevelopmental outcomes. This review details the multifactorial pathogenesis of preterm brain injury and neuroprotective strategies in use at present, including antenatal care, seizure management and non-pharmacological NICU care. We discuss treatment strategies that are being evaluated as potential interventions to improve the neurodevelopmental outcomes of infants born prematurely.

The longitudinal biochemical profiling of TBI in a drop weight model of TBI

Traumatic brain injury (TBI) is a major cause of mortality and disability worldwide, particularly among individuals under the age of 45. It is a complex, and heterogeneous disease with a multifaceted pathophysiology that remains to be elucidated. Metabolomics has the potential to identify metabolic pathways and unique biochemical profiles associated with TBI. Herein, we employed a longitudinal metabolomics approach to study TBI in a weight drop mouse model to reveal metabolic changes associated with TBI pathogenesis, severity, and secondary injury. Using proton nuclear magnetic resonance (1H NMR) spectroscopy, we biochemically profiled post-mortem brain from mice that suffered mild TBI (N = 25; 13 male and 12 female), severe TBI (N = 24; 11 male and 13 female) and sham controls (N = 16; 11 male and 5 female) at baseline, day 1 and day 7 following the injury. 1H NMR-based metabolomics, in combination with bioinformatic analyses, highlights a few significant metabolites associated with TBI severity and perturbed metabolism related to the injury. We report that the concentrations of taurine, creatinine, adenine, dimethylamine, histidine, N-Acetyl aspartate, and glucose 1-phosphate are all associated with TBI severity. Longitudinal metabolic observation of brain tissue revealed that mild TBI and severe TBI lead distinct metabolic profile changes. A multi-class model was able to classify the severity of injury as well as time after TBI with estimated 86% accuracy. Further, we identified a high degree of correlation between respective hemisphere metabolic profiles (r > 0.84, p < 0.05, Pearson correlation). This study highlights the metabolic changes associated with underlying TBI severity and secondary injury. While comprehensive, future studies should investigate whether: (a) the biochemical pathways highlighted here are recapitulated in the brain of TBI sufferers and (b) if the panel of biomarkers are also as effective in less invasively harvested biomatrices, for objective and rapid identification of TBI severity and prognosis.

EPO prevents neuroinflammation and relieves depression via JAK/STAT signaling

AIMS

Erythropoietin (EPO) is a glycoprotein cytokine that exerts therapeutic potential on neurological disorders by promoting neurogenesis and angiogenesis. However, its role as an antidepressant via anti-inflammatory axes is poorly explored. Furthermore, chronic inflammation can induce neuroinflammation, concurrent with depressive-like behaviors that anti-inflammatory and antidepressant agents could avert. Here, we aimed to elucidate the antidepressant potential of Erythropoietin (EPO) in the LPS-induced depression model.

MAIN METHODS

For in vivo analysis, mice were treated with LPS (2 mg/kg BW), Erythropoietin (EPO) (5000 U/kg/day), (Ruxolitinib,15 mg/kg), and K252a (25 μg/kg). Depressive-like behaviors were confirmed via behavior tests, including OFT, FST, SPT, and TST. Cytokines were measured via ELISA, while IBA-1/GFAP expression was determined by immunofluorescence. Further, the desired gene expression was measured by immunoblotting. For in vitro analysis, BV2 and N2a cell lines were cultured, treated with LPS, EPO, Ruxolitinib, and K252a, collected, and analyzed.

KEY FINDINGS

LPS treatment significantly induced neuroinflammation accompanied by depression-like behaviors in mice. However, EPO treatment rescued LPS-induced changes by averting cytokine production, secretion, and glial cell activation and reducing depressive-like behaviors in mice. Surprisingly, EPO treatment ameliorated LPS-induced JAK2/STAT5 signaling impairment, as validated by JAK2-antagonism. Furthermore, synaptic and dendritic spine defects and BNDF/TrkB signaling upon LPS administration could be prevented by EPO treatment.

SIGNIFICANCE

EPO could act as an antidepressant via its anti-inflammatory potential by regulating JAK2/STAT5 signaling.

Early Measures of TBI Severity Poorly Predict Later Individual Impairment in a Rat Fluid Percussion Model

BACKGROUND

Multiple measures of injury severity are suggested as common data elements in preclinical traumatic brain injury (TBI) research. The robustness of these measures in characterizing injury severity is unclear. In particular, it is not known how reliably they predict individual outcomes after experimental TBI.

METHODS

We assessed several commonly used measures of initial injury severity for their ability to predict chronic cognitive outcomes in a rat lateral fluid percussion (LFPI) model of TBI. At the time of injury, we assessed reflex righting time, neurologic severity scores, and 24 h weight loss. Sixty days after LFPI, we evaluated working memory using a spontaneous alternation T-maze task.

RESULTS

We found that righting time and weight loss had no correlation to chronic T-maze performance, while neurologic severity score correlated weakly.

DISCUSSION

Taken together, our results indicate that commonly used early measures of injury severity do not robustly predict longer-term outcomes. This finding parallels the uncertainty in predicting individual outcomes in TBI clinical populations.

Saffron extract and crocin exert anti-inflammatory and anti-oxidative effects in a repetitive mild traumatic brain injury mouse model

Saffron Crocus sativus L. (C. sativus) is a flower from the iridaceous family. Crocin, saffron’s major constituent, and saffron have anti-oxidative and anti-inflammatory activities. In this work, the neuroprotective effects of saffron and crocin are being investigated in a repetitive mild traumatic brain injury (rmTBI) mouse model. A weight drop model setup was employed to induce mild brain injury in male albino BABL/c mice weighing 30–40 g. Saffron (50 mg/kg) and crocin (30 mg/kg) were administrated intraperitoneally 30 min before mTBI induction. Behavioral tests were conducted to assess behavioral deficits including the modified neurological severity score (NSS), Morris water maze (MWM), pole climb test, rotarod test, and adhesive test. The levels of TNF alpha (TNF-α), interferon-gamma (IFN-γ), myeloperoxidase activity (MPO), malonaldehyde (MDA), and reduced glutathione (GSH) were measured. Histological analysis of different brain parts was performed. Both saffron and crocin demonstrated marked improved neurological, cognitive, motor, and sensorimotor functions. Besides, both compounds significantly reduced the oxidative stress and inflammatory processes. No abnormal histological features were observed in any of the injured groups. Saffron extract and crocin provide a neuroprotective effect in a mouse model of rmTBI by decreasing oxidative stress, inflammatory responses, and behavioral deficits.

Melatonin alleviates traumatic brain injury‑induced anxiety‑like behaviors in rats: Roles of the protein kinase A/cAMP‑response element binding signaling pathway

Melatonin is a hormone produced by the pineal gland. Given its capabilities of neuroprotection and low neurotoxicity, melatonin could be a therapeutic strategy for traumatic brain injury (TBI). The present study was conducted to determine the neuroprotective effects of melatonin on TBI-induced anxiety and the possible molecular mechanism. Rats were randomly divided into seven groups. The rodent model of TBI was established using the weight-drop method. Melatonin was administered by intraperitoneal injection at a dose of 10 mg/kg after TBI. H89 (0.02 mg/kg), a special protein kinase A (PKA) inhibitor, or dibutyryl-cyclic adenosine monophosphate (cAMP; 0.1 mg/kg), an activator of PKA, were administered by stereotactic injection of the brain to evaluate the roles of PKA and cAMP-response element-binding protein (CREB) in melatonin-related mood regulation, respectively. At 30 days post-TBI, the changes in anxiety-like behaviors in rats were measured using the open field and elevated plus maze tests. At 24 h post-TBI, the number of activated astrocytes and neuronal apoptosis were evaluated using immunofluorescence assay. The expression levels of inflammatory cytokines (TNF-α and IL-6) in the amygdala were measured using an enzyme-linked immunosorbent assay. The expression levels of PKA, phosphorylated (p)-PKA, CREB, p-CREB, NF-κB and p-NF-κB in the amygdala were detected using western blotting. It was revealed that melatonin partially reversed TBI-induced anxiety-like behavior in rats, and decreased the number of activated astrocytes and neuronal apoptosis in the amygdala induced by TBI. H89 partially blocked the neuroprotective effects of melatonin; while dibutyryl-cAMP not only reduced the H89-induced emotional disturbance but also enhanced the protective effects of melatonin against TBI. Overall, melatonin can alleviate TBI-induced anxiety-like behaviors in rats. Moreover, the underlying mechanism may be associated with the activation of the PKA/CREB signaling pathway.

Effect of erythropoietin administration on the expression of brain-derived neurotrophic factor, stromal cell-derived Factor-1, and neuron-specific enolase in traumatic brain injury: A literature review

Traumatic brain injury (TBI) is a major cause of death and lifelong disability around the world that predominantly affects young and middle-aged people. Erythropoietin (EPO) is a promising therapeutic agent for a variety of neurological injuries including TBI due to its neuroprotective effects. Here we review the impact of exogenous erythropoietin administration on the expression of brain-derived neurotrophic factor (BDNF), stromal cell-derived factor-1 (SDF-1), and neuron-specific enolase (NSE) levels in cerebrospinal fluid after TBI as biomarkers for neuron regeneration and survival to predict TBI outcome.

Beyond the Brain: Peripheral Interactions after Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability, and there are currently no pharmacological treatments known to improve patient outcomes. Unquestionably, contributing toward a lack of effective treatments is the highly complex and heterogenous nature of TBI. In this review, we highlight the recent surge of research that has demonstrated various central interactions with the periphery as a potential major contributor toward this heterogeneity and, in particular, the breadth of research from Australia. We describe the growing evidence of how extracranial factors, such as polytrauma and infection, can significantly alter TBI neuropathology. In addition, we highlight how dysregulation of the autonomic nervous system and the systemic inflammatory response induced by TBI can have profound pathophysiological effects on peripheral organs, such as the heart, lung, gastrointestinal tract, liver, kidney, spleen, and bone. Collectively, this review firmly establishes TBI as a systemic condition. Further, the central and peripheral interactions that can occur after TBI must be further explored and accounted for in the ongoing search for effective treatments.

Microglia: A Potential Drug Target for Traumatic Axonal Injury

Traumatic axonal injury (TAI) is a major cause of death and disability among patients with severe traumatic brain injury (TBI); however, no effective therapies have been developed to treat this disorder. Neuroinflammation accompanying microglial activation after TBI is likely to be an important factor in TAI. In this review, we summarize the current research in this field, and recent studies suggest that microglial activation plays an important role in TAI development. We discuss several drugs and therapies that may aid TAI recovery by modulating the microglial phenotype following TBI. Based on the findings of recent studies, we conclude that the promotion of active microglia to the M2 phenotype is a potential drug target for the treatment of TAI.

Traumatic Brain Injury: Mechanistic Insight on Pathophysiology and Potential Therapeutic Targets

Traumatic brain injury (TBI) causes brain damage, which involves primary and secondary injury mechanisms. Primary injury causes local brain damage, while secondary damage begins with inflammatory activity followed by disruption of the blood-brain barrier (BBB), peripheral blood cells infiltration, brain edema, and the discharge of numerous immune mediators including chemotactic factors and interleukins. TBI alters molecular signaling, cell structures, and functions. Besides tissue damage such as axonal damage, contusions, and hemorrhage, TBI in general interrupts brain physiology including cognition, decision-making, memory, attention, and speech capability. Regardless of the deep understanding of the pathophysiology of TBI, the underlying mechanisms still need to be assessed with a desired therapeutic agent to control the consequences of TBI. The current review gives a brief outline of the pathophysiological mechanism of TBI and various biochemical pathways involved in brain injury, pharmacological treatment approaches, and novel targets for therapy.

Potential anti-inflammatory effect of erythropoietin in non-clinical studies in vivo: A systematic review

Erythropoietin (EPO) is a hypoxia-induced hormone produced in adult kidneys with erythropoietic and non-erythropoietic effects. In vivo studies represent an important role to comprehend the efficacy and safety in the early phase of repurposing drugs. The aim is to evaluate the potential anti-inflammatory effect of EPO observed in animal models of disease. Following PRISMA statements, electronic database Medline via PubMed platform was used to search articles with the research expression ((erythropoietin [MeSH Terms]) AND (inflammation [MeSH Terms]) AND (disease models, animal [MeSH Terms])). The inclusion criteria were original articles, studies where EPO was administered, studies where inflammation was studied and/or evaluated, non-clinical studies in vivo with rodents, and articles published in English. Thirty-six articles met the criteria for qualitative analysis. Exogenous EPO was used in models of sepsis, traumatic brain injury, and autoimmune neuritis, with an average of 3000 IU/Kg for single and multiple doses, using mice and rats. Biomarkers such as immune-related effectors, cytokines, reactive oxygen species, prostaglandins, and other biomarkers were assessed. EPO has been recognized as a multifunctional cytokine with anti-inflammatory properties, showing its significant effect both in acute and chronic models of inflammation. Further non-clinical studies are suggested for the enlightenment of anti-inflammatory mechanisms of EPO in lower doses, allowing us to understand the translational data for humans.

Systemic low-dose erythropoietin administration improves the vascularization of collagen-glycosaminoglycan matrices seeded with adipose tissue-derived microvascular fragments

Adipose tissue-derived microvascular fragments (MVF) are used as vascularization units in tissue engineering. In this study, we investigated whether the vascularization capacity of MVF can be improved by systemic low-dose erythropoietin (EPO) administration. MVF were isolated from the epididymal fat of donor mice and seeded onto collagen-glycosaminoglycan matrices, which were implanted into full-thickness skin defects within dorsal skinfold chambers of recipient mice. Both donor and recipient mice were treated daily with either EPO (500 IU/kg) or vehicle (0.9% NaCl). The implants were analyzed by stereomicroscopy, intravital fluorescence microscopy, histology, and immunohistochemistry. EPO-treated MVF contained a comparable number of proliferating Ki67⁺ but less apoptotic cleaved caspase-3⁺ endothelial cells when compared to vehicle-treated controls. Moreover, EPO treatment accelerated and improved the in vivo vascularization, blood vessel maturation, and epithelialization of MVF-seeded matrices. These findings indicate that systemic low-dose EPO treatment is suitable to enhance the viability and network-forming capacity of MVF.

Neuropharmacology in traumatic brain injury: from preclinical to clinical neuroprotection?

Traumatic brain injury (TBI) constitutes a major health problem worldwide and is a leading cause of death and disability in individuals, contributing to devastating socioeconomic consequences. Despite numerous promising pharmacological strategies reported as neuroprotective in preclinical studies, the translation to clinical trials always failed, albeit the great diversity of therapeutic targets evaluated. In this review, first, we described epidemiologic features, causes, and primary and secondary injuries of TBI. Second, we outlined the current literature on animal models of TBI, and we described their goals, their advantages and disadvantages according to the species used, the type of injury induced, and their clinical relevance. Third, we defined the concept of neuroprotection and discussed its evolution. We also identified the reasons that might explain the failure of clinical translation. Then, we reviewed post‐TBI neuroprotective treatments with a focus on the following pleiotropic drugs, considered “low hanging fruit” with high probability of success: glitazones, glibenclamide, statins, erythropoietin, and progesterone, that were largely tested and demonstrated efficient in preclinical models of TBI. Finally, our review stresses the need to establish a close cooperation between basic researchers and clinicians to ensure the best clinical translation for neuroprotective strategies for TBI.

Erythropoietin-derived peptide treatment reduced neurological deficit and neuropathological changes in a mouse model of tauopathy

BACKGROUND

Prominent activation of microglial immune/inflammatory processes is a characteristic feature of brains of patients with tauopathies including Alzheimer's disease (AD), suggesting that neuroinflammation may be a critical factor in their pathogenesis. Strategies aimed at developing new therapeutics for tauopathies based on anti-inflammation or immunomodulation are likely to be promising avenues of research. We previously developed JM4-a 19'mer cyclic peptide derived from the first loop of human erythropoietin. This peptide possesses beneficial immune modulatory and tissue protective effects while lacking the undesirable side effects of full-length erythropoietin. In this preclinical study, we investigated the effect of chronic JM4 treatment on the PS19 mouse that carries the P301S mutant human tau gene, linked to a form of frontotemporal dementia. This transgenic mouse has been widely used as a model of tauopathies including AD and related dementias.

METHODS

Daily subcutaneous treatment of female PS19 mice with JM4 was initiated before disease onset and continued on for the animals' lifespan. The progression of neurological deficit and the lifespan of these mice were assessed. To evaluate the effect of JM4 treatment on cognition of these animals, the PS19 mice underwent Barnes maze test and elevated plus maze test. In addition, neuronal loss, phosphorylated tau aggregation, and microglial activation were assessed using immunohistochemistry of PS19 mouse brain sections.

RESULTS

JM4 treatment of PS19 mice initiated before disease onset reduced neurological deficit, prolonged lifespan, and rescued memory impairment. The beneficial effects of JM4 were accompanied by reductions in neuronal loss, phosphorylated tau aggregation, and microglial activation in the PS19 mouse brain.

LIMITATIONS

Use of a single dose of JM4 and female mice only.

CONCLUSION

JM4 is a potential novel therapeutic agent for the treatment of tauopathies including AD and related dementias.

The effect of combination therapy with erythropoietin and methylprednisolone in patients with traumatic cervical spinal cord injury: a pilot randomized controlled trial

STUDY DESIGN

Pilot double-blinded randomized controlled trial.

OBJECTIVES

To investigate the additive effect of recombinant human erythropoietin (rhEPO) on functional outcome and disability in patients with traumatic cervical spinal cord injury (TCSCI).

SETTINGS

University-affiliated hospital in Mashhad, Iran.

METHODS

Patients with acute TCSCI admitted within 8 h after injury were randomly assigned to receive only methylprednisolone (M group) or rhEPO 500 IU/mL plus methylprednisolone (M + E group). All the patients underwent surgery within the next several days. Neurological function was assessed on admission, and at 6th and 12th months after the injury according to the sphincter function and American spinal cord injury association (ASIA) scale.

RESULTS

Overall, 54 patients (mean age: 39.7 ± 13.3 years) including 46 (85%) males were studied in two groups of 27. The likelihood of developing adverse neurological outcomes (ASIA impairment score of A compared to D or E) was not significantly different between the groups after 6 (OR = 0.39, 95% CI = 0.03-4.80, P = 0.46) and 12 months (OR = 0.83, 95% CI = 0.11-6.11, P = 0.86). The groups also showed no significant difference in 1-year mortality (OR = 0.83, 95% CI = 0.25-2.74, P = 0.76).

CONCLUSIONS

It is not clear whether combination therapy with erythropoietin compared to methylprednisolone alone improves neurological functions of patients with TCSCI. Our study provides interim data to guide future larger definitive trials.

Traumatic axonal injury (TAI): definitions, pathophysiology and imaging-a narrative review

Introduction

Traumatic axonal injury (TAI) is a condition defined as multiple, scattered, small hemorrhagic, and/or non-hemorrhagic lesions, alongside brain swelling, in a more confined white matter distribution on imaging studies, together with impaired axoplasmic transport, axonal swelling, and disconnection after traumatic brain injury (TBI). Ever since its description in the 1980s and the grading system by Adams et al., our understanding of the processes behind this entity has increased.

Methods

We performed a scoping systematic, narrative review by interrogating Ovid MEDLINE, Embase, and Google Scholar on the pathophysiology, biomarkers, and diagnostic tools of TAI patients until July 2020.

Results

We underline the misuse of the Adams classification on MRI without proper validation studies, and highlight the hiatus in the scientific literature and areas needing more research. In the past, the theory behind the pathophysiology relied on the inertial force exerted on the brain matter after severe TBI inducing a primary axotomy. This theory has now been partially abandoned in favor of a more refined theory involving biochemical processes such as protein cleavage and DNA breakdown, ultimately leading to an inflammation cascade and cell apoptosis, a process now described as secondary axotomy.

Conclusion

The difference in TAI definitions makes the comparison of studies that report outcomes, treatments, and prognostic factors a daunting task. An even more difficult task is isolating the outcomes of isolated TAI from the outcomes of severe TBI in general. Targeted bench-to-bedside studies are required in order to uncover further pathways involved in the pathophysiology of TAI and, ideally, new treatments.

Preparation and Evaluation of Recombinant Human Erythropoietin Loaded Tween 80-Albumin Nanoparticle for Traumatic Brain Injury Treatment

OBJECTIVE

Traumatic brain injury (TBI) is a serious health problem with few available treatment options. Rh-erythropoietin (rh-EPO) is a potential therapeutic drug for TBI, but it cannot cross the blood-brain barrier (BBB) directly. In this regard, a novel strategy to deliver rh-EPO for enhanced TBI treatment is via the development of Tween 80 modified albumin nanoparticles using electrostatic spray technology.

METHODS

The rh-EPO loaded Tween 80 modified albumin nanoparticles (rh-EPO-Tw-ABNPs) were prepared by electrostatic spray technology, while the process parameters were optimized via a single factor design. Investigation of physicochemical properties, bioactivity and stability of rh-EPO-Tw-ABNPs was carried out. The in vitro release and biocompatibility with nerve cells were also analyzed. The in vivo brain targeting efficiency, brain edema relieving effect and the expression of aquaporin 4 (AQP4) and glial fibrillary acidic protein (GFAP) in the brain were evaluated in TBI model rats.

RESULTS

The particle size of optimal rh-EPO-Tw-ABNPs was about 438 ± 45 nm, with a zeta potential of -25.42 ± 0.8 mv. The average drug loading ratio of rh-EPO-Tw-ABNPs was 21.3± 3.7 IU/mg with a relative bioactivity of 91.6 ± 4.1%. The in vitro release of rh-EPO from the nanoparticles was rather slow, while neither the blank Tw-ABNPs nor rh-EPO-Tw-ABNPs exhibited toxicity on the microglia cells. Furthermore, in vivo experiments indicated that the rh-EPO-Tw-ABNPs could enhance the distribution of EPO in the brain and relieve brain edema more effectively. Moreover, compared with an rh-EPO injection, the rh-EPO-Tw-ABNPs could increase the AQP4 level but reduced GFAP expression in the brain with more efficiency.

CONCLUSION

The rh-EPO-Tw-ABNPs could enhance the transport of rh-EPO into the brain with superior therapeutic effect for TBI.

Drugs with anti-inflammatory effects to improve outcome of traumatic brain injury: a meta-analysis

Outcome after traumatic brain injury (TBI) varies largely and degree of immune activation is an important determinant factor. This meta-analysis evaluates the efficacy of drugs with anti-inflammatory properties in improving neurological and functional outcome. The systematic search following PRISMA guidelines resulted in 15 randomized placebo-controlled trials (3734 patients), evaluating progesterone, erythropoietin and cyclosporine. The meta-analysis (15 studies) showed that TBI patients receiving a drug with anti-inflammatory effects had a higher chance of a favorable outcome compared to those receiving placebo (RR = 1.15; 95% CI 1.01–1.32, p = 0.041). However, publication bias was indicated together with heterogeneity (I² = 76.59%). Stratified analysis showed that positive effects were mainly observed in patients receiving this treatment within 8 h after injury. Subanalyses by drug type showed efficacy for progesterone (8 studies, RR 1.22; 95% CI 1.01–1.47, p = 0.040), again heterogeneity was high (I² = 62.92%) and publication bias could not be ruled out. The positive effect of progesterone covaried with younger age and was mainly observed when administered intramuscularly and not intravenously. Erythropoietin (4 studies, RR 1.20; p = 0.110; I² = 76.59%) and cyclosporine (3 studies, RR 0.75; p = 0.189, I² = 0%) did not show favorable significant effects. While negative findings for erythropoietin may reflect insufficient power, cyclosporine did not show better outcome at all. Current results do not allow firm conclusions on the efficacy of drugs with anti-inflammatory properties in TBI patients. Included trials showed heterogeneity in methodological and sample parameters. At present, only progesterone showed positive results and early administration via intramuscular administration may be most effective, especially in young people. The anti-inflammatory component of progesterone is relatively weak and other mechanisms than mitigating overall immune response may be more important.

A New Model of Repetitive Traumatic Brain Injury in Mice

Repetitive traumatic brain injury (rTBI) is a major health care concern that causes substantial neurological impairment. To better understand rTBI, we introduced a new model of rTBI in mice induced by sudden rotation in the coronal plane combined with lateral translation delivered twice at an interval of 24 h. By routine histology, histological examination of Prussian blue-stained sections revealed the presence of microbleed in the corpus callosum and brain stem. Amyloid precursor protein (β-APP) and neurofilament heavy-chain (NF-200) immunohistochemistry demonstrated axonal injury following rTBI. Swelling, waving, and enlargement axons were observed in the corpus callosum and brain stem 24 h after injury by Bielschowsky staining. Ultrastructural studies by electron microscopy provided further insights into the existence and progression of axonal injury. rTBI led to widespread astrogliosis and microgliosis in white matter, as well as significantly increased levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β. rTBI mice showed a significantly increased loss of righting reflex (LRR) duration within each time point compared with that of sham animals, which was under 15 min. rTBI mice exhibited depression-like behavior at 1 month. rTBI mice also demonstrated deficits in MWM testing. These results suggested that this model might be suitable for investigating rTBI pathophysiology and evaluating preclinical candidate therapeutics.

Protective impacts of erythropoietin on myelinization of oligodendrocytes and schwann cells in CNS and PNS following cuprizone-induced multiple sclerosis- histology, molecular, and functional studies

BACKGROUND

Multiple sclerosis (MS) is known as one of the chronic inflammatory diseases characterized by lesions in the central nervous system (CNS) and peripheral nervous system(PNS) resulting in serious cognitive or physical disabilities as well as neurological disorders. Thus, protective effects of erythropoietin(EPO) on myelinization of oligodendrocytes and schwann cells respectively in CNS and PNS following MS induced by cuprizone (CPZ) administration in young female mice.

METHODOLOGY

To meet the objectives of this study; a chow with 0.2 % CPZ was used to feed young female C57BL/6 J mice for six weeks. After three weeks, EPO (5000 IU/kg body weight) was administered via daily intra-peritoneal injection for simultaneous treatment of the mice. Measurement of latency and amplitude of the compound muscle action potential (CMAP) of gastrocnemius muscle was also performed every week during a six-week demyelination interval, and then examinations were fulfilled on the histological sections of the brain and sciatic nerve. Therefore, we focused on the removal of the sciatic and sciatic nerve specimens and analysis of the use of the stereological procedures, western blot, immuno-histochemistry, and gene expression.

RESULTS

According to the results of this study, MBP levels increased in oligodendrocytes (OLs) in the treated mice. Moreover, EPO could concurrently enhance motor coordination and muscle activity. Analysis showed the significant enhancement of the gene expression of MBP, MAG, and S100, as well as stereological variables in the treatment group in comparison with the cuprizone (CPZ) group.

CONCLUSION

Findings could help further understand the alleviation of the detrimental impacts of CPZ using the OLs that would be capable of increasing the level of S100, MAG, and MBP.

Traumatic Brain Injuries: Pathophysiology and Potential Therapeutic Targets

Traumatic brain injury (TBI) remains one of the leading causes of morbidity and mortality amongst civilians and military personnel globally. Despite advances in our knowledge of the complex pathophysiology of TBI, the underlying mechanisms are yet to be fully elucidated. While initial brain insult involves acute and irreversible primary damage to the parenchyma, the ensuing secondary brain injuries often progress slowly over months to years, hence providing a window for therapeutic interventions. To date, hallmark events during delayed secondary CNS damage include Wallerian degeneration of axons, mitochondrial dysfunction, excitotoxicity, oxidative stress and apoptotic cell death of neurons and glia. Extensive research has been directed to the identification of druggable targets associated with these processes. Furthermore, tremendous effort has been put forth to improve the bioavailability of therapeutics to CNS by devising strategies for efficient, specific and controlled delivery of bioactive agents to cellular targets. Here, we give an overview of the pathophysiology of TBI and the underlying molecular mechanisms, followed by an update on novel therapeutic targets and agents. Recent development of various approaches of drug delivery to the CNS is also discussed.

Immune-Based Therapies for Traumatic Brain Injury: Insights from Pre-Clinical Studies

Traumatic Brain Injury (TBI) is a major public health problem. It is the leading cause of death and disability, especially among children and young adults. The neurobiology basis underlying TBI pathophysiology remains to be fully revealed. Over the past years, emerging evidence has supported the hypothesis that TBI is an inflammatory based condition, paving the way for the development of potential therapeutic targets. There is no treatment capable to prevent or minimize TBIassociated outcomes. Therefore, the search for effective therapies is a priority goal. In this context, animal models have become valuable tools to study molecular and cellular mechanisms involved in TBI pathogenesis as well as novel treatments. Herein, we discuss therapeutic strategies to treat TBI focused on immunomodulatory and/or anti-inflammatory approaches in the pre-clinical setting.

A Systematic Review of Closed Head Injury Models of Mild Traumatic Brain Injury in Mice and Rats

Mild TBI (mTBI) is a significant health concern. Animal models of mTBI are essential for understanding mechanisms, and pathological outcomes, as well as to test therapeutic interventions. A variety of closed head models of mTBI that incorporate different aspects (i.e., biomechanics) of the mTBI have been reported. The aim of the current review was to compile a comprehensive list of the closed head mTBI rodent models, along with the common data elements, and outcomes, with the goal to summarize the current state of the field. Publications were identified from a search of PubMed and Web of Science and screened for eligibility following PRISMA guidelines. Articles were included that were closed head injuries in which the authors classified the injury as mild in rats or mice. Injury model and animal-specific common data elements, as well as behavioral and histological outcomes, were collected and compiled from a total of 402 articles. Our results outline the wide variety of methods used to model mTBI. We also discovered that female rodents and both young and aged animals are under-represented in experimental mTBI studies. Our findings will aid in providing context comparing the injury models and provide a starting point for the selection of the most appropriate model of mTBI to address a specific hypothesis. We believe this review will be a useful starting place for determining what has been done and what knowledge is missing in the field to reduce the burden of mTBI.

Cend1, a Story with Many Tales: From Regulation of Cell Cycle Progression/Exit of Neural Stem Cells to Brain Structure and Function. Stem Cells Int. 2019;2019:2054783. [PMID: 31191667 PMCID: PMC6525816 DOI: 10.1155/2019/2054783]

Neural stem/precursor cells (NPCs) generate the large variety of neuronal phenotypes comprising the adult brain. The high diversity and complexity of this organ have its origin in embryonic life, during which NPCs undergo symmetric and asymmetric divisions and then exit the cell cycle and differentiate to acquire neuronal identities. During these processes, coordinated regulation of cell cycle progression/exit and differentiation is essential for generation of the appropriate number of neurons and formation of the correct structural and functional neuronal circuits in the adult brain. Cend1 is a neuronal lineage-specific modulator involved in synchronization of cell cycle exit and differentiation of neuronal precursors. It is expressed all along the neuronal lineage, from neural stem/progenitor cells to mature neurons, and is associated with the dynamics of neuron-generating divisions. Functional studies showed that Cend1 has a critical role during neurogenesis in promoting cell cycle exit and neuronal differentiation. Mechanistically, Cend1 acts via the p53-dependent/Cyclin D1/pRb signaling pathway as well as via a p53-independent route involving a tripartite interaction with RanBPM and Dyrk1B. Upon Cend1 function, Notch1 signaling is suppressed and proneural genes such as Mash1 and Neurogenins 1/2 are induced. Due to its neurogenic activity, Cend1 is a promising candidate therapeutic gene for brain repair, while the Cend1 minimal promoter is a valuable tool for neuron-specific gene delivery in the CNS. Mice with Cend1 genetic ablation display increased NPC proliferation, decreased migration, and higher levels of apoptosis during development. As a result, they show in the adult brain deficits in a range of motor and nonmotor behaviors arising from irregularities in cerebellar cortex lamination and impaired Purkinje cell differentiation as well as a paucity in GABAergic interneurons of the cerebral cortex, hippocampus, and amygdala. Taken together, these studies highlight the necessity for Cend1 expression in the formation of a structurally and functionally normal brain.

Erythropoietin reduces nerve demyelination, neuropathic pain behavior and microglial MAPKs activation through erythropoietin receptors on Schwann cells in a rat model of peripheral neuropathy

Neuroprotective effects of erythropoietin (EPO) on peripheral nerve injury remain uncertain. This study investigated the efficacy of EPO in attenuating median nerve chronic constriction injury (CCI)-induced neuropathy. Animals received an intraneural injection of EPO at doses of 1,000, 3,000, or 5,000 units/kg 15 min before median nerve CCI. Afterwards, the behavioral and electrophysiological tests were conducted. Immunohistochemistry and immunoblotting were used for qualitative and quantitative analysis of microglial and mitogen-activated protein kinases (MAPKs), including p38, JNK, and ERK, activation. Enzyme-linked immunosorbent assay and microdialysis were applied to measure pro-inflammatory cytokine and glutamate responses, respectively. EPO pre-treatment dose-dependently ameliorated neuropathic pain behavior, decreased microglial and MAPKs activation, and diminished the release of pro-inflammatory cytokines and glutamate in the ipsilateral cuneate nucleus after CCI. Moreover, EPO pre-treatment preserved myelination of the injured median nerve on morphological investigation and suppressed injury-induced discharges. We also observed that EPO receptor (EPOR) expression was up-regulated in the injured nerve after CCI. Double immunofluorescence showed that EPOR was localized to Schwann cells. Furthermore, siRNA-mediated knockdown of EPOR expression eliminated the therapeutic effects of EPO on attenuating the microglial and MAPKs activation, pro-inflammatory cytokine responses, injury discharges, and neuropathic pain behavior in CCI rats. In conclusion, binding of EPO to its receptors on Schwann cells maintains myelin integrity and blocks ectopic discharges in the injured median nerve, that in the end contribute to attenuation of neuropathic pain via reducing glutamate release from primary afferents and inhibiting activation of microglial MAPKs and production of pro-inflammatory cytokines.

Erythropoietin and Nrf2: key factors in the neuroprotection provided by apo-lactoferrin

Among the properties of lactoferrin (LF) are bactericidal, antianemic, immunomodulatory, antitumour, antiphlogistic effects. Previously we demonstrated its capacity to stabilize in vivo HIF-1-alpha and HIF-2-alpha, which are redox-sensitive multiaimed transcription factors. Various tissues of animals receiving recombinant human LF (rhLF) responded by expressing the HIF-1-alpha target genes, hence such proteins as erythropoietin (EPO), ceruloplasmin, etc. were synthesized in noticeable amounts. Among organs in which EPO synthesis occurred were brain, heart, spleen, liver, kidneys and lungs. Other researchers showed that EPO can act as a protectant against severe brain injury and status epilepticus in rats. Therefore, we tried rhLF as a protector against the severe neurologic disorders developed in rats, such as the rotenone-induced model of Parkinson's disease and experimental autoimmune encephalomyelitis as a model of multiple sclerosis, and observed its capacity to mitigate the grave symptoms. Moreover, an intraperitoneal injection of rhLF into mice 1 h after occlusion of the medial cerebral artery significantly diminished the necrosis area measured on the third day in the ischaemic brain. During this period EPO was synthesized in various murine tissues. It was known that EPO induces nuclear translocation of Nrf2, which, like HIF-1-alpha, is a transcription factor. In view that under conditions of hypoxia both factors demonstrate a synergistic protective effect, we suggested that LF activates the Keap1/Nrf2 signaling pathway, an important link in proliferation and differentiation of normal and malignant cells. J774 macrophages were cultured for 3 days without or in the presence of ferric and ferrous ions (RPMI-1640 and DMEM/F12, respectively). Then cells were incubated with rhLF or Deferiprone. Confocal microscopy revealed nuclear translocation of Nrf2 (the key event in Keap1/Nrf2 signaling) induced by apo-rhLF (iron-free, RPMI-1640). The reference compound Deferiprone (iron chelator) had the similar effect. Upon iron binding (in DMEM/F12) rhLF did not activate the Keap1/Nrf2 pathway. Added to J774, apo-rhLF enhanced transcription of Nrf2-dependent genes coding for glutathione S-transferase P and heme oxygenase-1. Western blotting revealed presence of Nrf2 in mice brain after 6 days of oral administration of apo-rhLF, but not Fe-rhLF or equivalent amount of PBS. Hence, apo-LF, but not holo-LF, induces the translocation of Nrf2 from cytoplasm to the nucleus, probably due to its capacity to induce EPO synthesis.

Protective Effects of Cornel Iridoid Glycoside in Rats After Traumatic Brain Injury

Cornel iridoid glycoside (CIG) is the active ingredient extracted from Cornus officinalis. Our previous studies showed that CIG had protective effects on several brain injury models. In the present study, we aimed to examine the effects and elucidate the mechanisms of CIG against traumatic brain injury (TBI). TBI was induced in the right cerebral cortex of male adult rats. The neurological and cognitive functions were evaluated by modified neurological severity score (mNSS) and object recognition test (ORT), respectively. The level of serum S100β was measured by an ELISA method. Nissl staining was used to estimate the neuron survival in the brain. The expression of proteins was determined by western blot and/or immunohistochemical staining. We found that intragastric administration of CIG in TBI rats ameliorated the neurological defects and cognitive impairment, and alleviated the neuronal loss in the injured brain. In the acute stage of TBI (24-72 h), CIG decreased the level of S100β in the serum and brain, increased the ratio of Bcl-2/Bax and decreased the expression of caspase-3 in the injured cortex. Moreover, the treatment with CIG for 30 days increased the levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), enhanced the expression of synapsin I, synaptophysin and postsynaptic density protein 95 (PSD-95), and inhibited the apoptosis-regulating factors in the chronic stage of TBI. The present study demonstrated that CIG had neuroprotective effects against TBI through inhibiting apoptosis in the acute stage and promoting neurorestoration in the chronic stage. The results suggest that CIG may be beneficial to TBI therapy.

Erythropoietin Attenuates the Brain Edema Response after Experimental Traumatic Brain Injury

Erythropoietin (EPO) has neuroprotective effects in multiple central nervous system (CNS) injury models; however EPO's effects on traumatic brain edema are elusive. To explore EPO as an intervention in traumatic brain edema, male Sprague–Dawley (SD) rats were subjected to blunt, controlled traumatic brain injury (TBI). Animals were randomized to EPO 5000 IU/kg or saline (control group) intraperitoneally within 30 min after trauma and once daily for 4 consecutive days. Brain MRI, immunohistofluorescence, immunohistochemistry, and quantitative protein analysis were performed at days 1 and 4 post- trauma. EPO significantly prevented the loss of the tight junction protein zona occludens 1 (ZO-1) observed in control animals after trauma. The decrease of ZO-1 in the control group was associated with an immunoglobulin (Ig)G increase in the perilesional parenchyma, indicating blood–brain barrier (BBB) dysfunction and increased permeability. EPO treatment attenuated decrease in apparent diffusion coefficient (ADC) after trauma, suggesting a reduction of cytotoxic edema, and reduced the IgG leakage, indicating that EPO contributed to preserve BBB integrity and attenuated vasogenic edema. Animals treated with EPO demonstrated conserved levels of aquaporin 4 (AQP4) protein expression in the perilesional area, whereas control animals showed a reduction of AQP4. We show that post TBI administration of EPO decreases early cytotoxic brain edema and preserves structural and functional properties of the BBB, leading to attenuation of the vasogenic edema response. The data support that the mechanisms involve preservation of the tight junction protein ZO-1 and the water channel AQP4, and indicate that treatment with EPO may have beneficial effects on the brain edema response following TBI.

Treatment of Traumatic Brain Injury with Vepoloxamer (Purified Poloxamer 188)

Vepoloxamer is an amphipathic polymer that has shown potent hemorrheologic, cytoprotective, and anti-inflammatory effects in both pre-clinical and clinical studies. This study was designed to investigate the therapeutic effects of vepoloxamer on sensorimotor and cognitive functional recovery in rats after traumatic brain injury (TBI) induced by controlled cortical impact. Young adult male Wistar rats were randomly divided into the following groups: 1) sham; 2) saline; or 3) vepoloxamer. Vepoloxamer (300 mg/kg) or saline was administered over 60 min via intravenous infusion into tail veins starting at 2 h post-injury. Sensorimotor function and spatial learning were assessed using a modified neurological severity score and foot fault test, and Morris water maze test, respectively. The animals were sacrificed 35 days after injury and their brains were processed for measurement of lesion volume and neuroinflammation. Compared with the saline treatment, vepoloxamer initiated 2 h post-injury significantly improved sensorimotor functional recovery (Days 1-35; p < 0.0001) and spatial learning (Days 32-35; p < 0.0001), reduced cortical lesion volume by 20%, and reduced activation of microglia/macrophages and astrogliosis in many brain regions including injured cortex, corpus callosum, and hippocampus, as well as normalized the bleeding time and reduced brain hemorrhage and microthrombosis formation. In summary, vepoloxamer treatment initiated 2 h post-injury provides neuroprotection and anti-inflammation in rats after TBI and improves functional outcome, indicating that vepoloxamer treatment may have potential value for treatment of TBI. Further investigation of the optimal dose and therapeutic window of vepoloxamer treatment for TBI and the mechanisms underlying beneficial effects are warranted.

No evidence for direct effects of recombinant human erythropoietin on cerebral blood flow and metabolism in healthy humans

Erythropoietin (EPO) is expressed in human brain tissue, but its exact role is unknown. EPO may improve the efficiency of oxidative metabolism and has neuroprotective properties against hypoxic injuries in animal models. We aimed to investigate the effect of recombinant human EPO (rHuEPO) administration on healthy cerebral metabolism in humans during normoxia and during metabolic stress by inhalation of 10% O₂ hypoxic air. Twenty-four healthy men participated in a two-arm double-blind placebo-controlled trial. rHuEPO was administered as a low dose (5,000 IU) over 4 wk ( n = 12) or as a high dose (500 IU·kg body wt^-1·day^-1) for three consecutive days ( n = 12). Global cerebral blood flow (CBF) and metabolic rate of glucose (CMR_glc) were measured with positron emission tomography. CBF, metabolic rate of oxygen ([Formula: see text]), and cerebral lactate concentration were measured by magnetic resonance imaging and spectroscopy. Low-dose treatment increased hemoglobin and was associated with a near-significant decrease in CBF during baseline normoxia. High-dose treatment caused no change in CBF. Neither treatment had an effect on normoxia CMR_glc, [Formula: see text], or lactate concentration or an effect on the cerebral metabolic response to inhalation of hypoxic air. In conclusion, the study found no evidence for a direct effect of rHuEPO on cerebral metabolism. NEW & NOTEWORTHY We demonstrate with magnetic resonance imaging and positron emission tomography that administration of erythropoietin does not have a substantial direct effect on healthy human resting cerebral blood flow or effect on cerebral glucose and oxygen metabolism. Also, administration of erythropoietin did not have a direct effect on the metabolic response to acute hypoxic stress in healthy humans, and a suggested neuroprotective effect from erythropoietin is therefore likely not a direct effect of erythropoietin on cerebral metabolism.

Erythropoietin regulates immune/inflammatory reaction and improves neurological function outcomes in traumatic brain injury

INTRODUCTION

Traumatic brain injury (TBI) remains a leading cause of disability and death among young people in China. Unfortunately, no specific pharmacological agents to block the progression of secondary brain injury have been approved for clinical treatment. Recently, neuroprotective effects of erythropoietin (EPO) have been demonstrated in addition to its principal function in erythropoiesis, and hence it is viewed as a potential drug for TBI. In this study, we have investigated the neuroprotective effects of EPO associated with immune/inflammatory modulation in a mouse experimental TBI model.

METHODS

EPO (5000 U/kg body weight, i.p.) was injected at 1 hr, 1, 2, and 3 days after TBI, and its effect on cognitive function, brain edema, immune/inflammatory cells including regulatory T cells (Tregs), neutrophils, CD3⁺ T cells, and microglia, cytokines including interleukin-10 (IL-10), transforming growth factor-β (TGF-β), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) were evaluated at different time points after treatment.

RESULTS

EPO treatment significantly decreased brain edema and improved cognitive function when compared to Saline-treated mice (p < .05). EPO treatment also significantly increased Tregs level in spleen and injured brain tissue as well as significantly reduced the infiltration and activation of immune/inflammatory cells (neutrophils, CD3⁺T cells, and microglia) in the injured hemisphere compared to Saline-treated control animals (p < .05). In addition, ELISA analysis demonstrated that EPO treatment increased the expression of anti-inflammatory cytokine IL-10, but decreased the expression of proinflammatory cytokine IL-1β and TNF-α in the injured brain tissue (p < .05).

CONCLUSIONS

These findings suggest that EPO could improve neurological and cognitive functional outcomes as well as regulate immune/inflammatory reaction in TBI.

Erythropoiesis-stimulating Agents in Critically Ill Trauma Patients: A Systematic Review and Meta-analysis

OBJECTIVE

To perform a meta-analysis of all relevant randomized controlled trials assessing the effect of erythropoiesis-stimulating agents (ESAs) in critically ill trauma patients.

BACKGROUND

ESAs have effects beyond erythropoiesis. The administration of the ESA epoetin alfa to critically ill trauma patients has been associated with a reduction in mortality.

METHODS

We performed a systematic review and meta-analysis with trial sequential analysis. We searched Medline, Medline in Process, and other nonindexed citations, EMBASE, and the Cochrane Database from inception until September 9, 2015, for randomized controlled trials comparing ESAs to placebo (or no ESA).

RESULTS

We identified 9 eligible studies that randomly assigned 2607 critically ill patients after trauma to an ESA or placebo (or no ESA). Compared with placebo (or no ESA), ESA therapy was associated with a substantial reduction in mortality [risk ratio (RR) 0.63, 95% confidence interval (CI) 0.49-0.79, P = 0.0001, I = 0%). In patients with traumatic brain injury, ESA therapy did not increase the number of patients surviving with moderate disability or good recovery (RR 1.00, 95% CI 0.88-1.15, P = 0.95, I = 0%). With the dosing regimens employed in the included studies, ESA therapy did not increase the risk of lower limb proximal deep venous thrombosis (RR 0.97, 95% CI 0.72-1.29, P = 0.78, I = 0%).

CONCLUSIONS

The administration of ESAs to critically ill trauma patients is associated with a significant improvement in mortality without an increase in the rate of lower limb proximal deep venous thrombosis. Given the worldwide public health significance of these findings research to validate or refute them is required.

Erythropoietin Treatment in Traumatic Brain Injury: Operation Brain Trauma Therapy

Experimental studies targeting traumatic brain injury (TBI) have reported that erythropoietin (EPO) is an endogenous neuroprotectant in multiple models. In addition to its neuroprotective effects, it has also been shown to enhance reparative processes including angiogenesis and neurogenesis. Based on compelling pre-clinical data, EPO was tested by the Operation Brain Trauma Therapy (OBTT) consortium to evaluate therapeutic potential in multiple TBI models along with biomarker assessments. Based on the pre-clinical TBI literature, two doses of EPO (5000 and 10,000 IU/kg) were tested given at 15 min after moderate fluid percussion brain injury (FPI), controlled cortical impact (CCI), or penetrating ballistic-like brain injury (PBBI) with subsequent behavioral, histopathological, and biomarker outcome assessments. There was a significant benefit on beam walk with the 5000 IU dose in CCI, but no benefit on any other motor task across models in OBTT. Also, no benefit of EPO treatment across the three TBI models was noted using the Morris water maze to assess cognitive deficits. Lesion volume analysis showed no treatment effects after either FPI or CCI; however, with the 5000 IU/kg dose of EPO, a paradoxical increase in lesion volume and percent hemispheric tissue loss was seen after PBBI. Biomarker assessments included measurements of glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase-L1 (UCH-L1) in blood at 4 or 24 h after injury. No treatment effects were seen on biomarker levels after FPI, whereas treatment at either dose exacerbated the increase in GFAP at 24 h in PBBI but attenuated 24-4 h delta UCH-L1 levels at high dose in CCI. Our data indicate a surprising lack of efficacy of EPO across three established TBI models in terms of behavioral, histopathological, and biomarker assessments. Although we cannot rule out the possibility that other doses or more prolonged treatment could show different effects, the lack of efficacy of EPO reduced enthusiasm for its further investigation in OBTT.

Peptide Pharmacological Approaches to Treating Traumatic Brain Injury: a Case for Arginine-Rich Peptides

Traumatic brain injury (TBI) has a devastating effect on victims and their families, and has profound negative societal and economic impacts, a situation that is further compounded by the lack of effective treatments to minimise injury after TBI. The current strategy for managing TBI is partly through preventative measures and partly through surgical and rehabilitative interventions. Secondary brain damage remains the principal focus for the development of a neuroprotective therapeutic. However, the complexity of TBI pathophysiology has meant that single-action pharmacological agents have been largely unsuccessful in combatting the associated brain injury cascades, while combination therapies to date have proved equally ineffective. Peptides have recently emerged as promising lead agents for the treatment of TBI, especially those rich in the cationic amino acid, arginine. Having been shown to lessen the impact of ischaemic stroke in animal models, there are reasonable grounds to believe that arginine-rich peptides may have neuroprotective therapeutic potential in TBI. Here, we review a range of peptides previously examined as therapeutic agents for TBI. In particular, we focus on cationic arginine-rich peptides -- a new class of agents that growing evidence suggests acts through multiple neuroprotective mechanisms.

Erythropoietin Induces Excessive Neointima Formation: A Study in a Rat Carotid Artery Model of Vascular Injury

A therapeutic strategy that would mitigate the events leading to hyperplasia and facilitate re-endothelialization of an injured artery after balloon angioplasty could be effective for a long-term patency of the artery. It is hypothesized that erythropoietin (EPO), which has both anti-inflammatory and antiapoptotic properties, will prevent hyperplasia, and its ability to proliferate and mobilize endothelial progenitor cells will re-endothelialize the injured artery. To test this hypothesis, EPO (5000 IU/kg) in solution was injected intraperitoneally 6 hours before vascular injury and then on every alternate day for a week or as a single dose (5000 IU/kg) in a sustained release gel formulation 1 week before the vascular injury. Morphometric analysis revealed nearly continuous re-endothelialization of the injured artery in EPO solution-treated animals (90% vs less than 20% in saline control); however, the treatment also caused excessive neointima formation (intima/media ratio, 2.10 ± 0.09 vs 1.60 ± 0.02 saline control, n = 5, P < .001). The EPO gel also induced similar excessive neointima formation. Immunohistochemical analysis of the injured arteries from the animals treated with EPO solution demonstrated a significant angiogenic response in adventitia and media, thus explaining the formation of excessive neointima. Although the results are in contrast to expectation, they explain a greater degree of stenosis seen in hemodialysis access fistulas in patients who are on EPO therapy for anemic condition. The results also caution the use of EPO, particularly in patients who are at a risk of vascular injury or are suffering from an atherosclerotic condition.

A mouse model of weight-drop closed head injury: emphasis on cognitive and neurological deficiency

Traumatic brain injury (TBI) is a leading cause of death and disability in individuals worldwide. Producing a clinically relevant TBI model in small-sized animals remains fairly challenging. For good screening of potential therapeutics, which are effective in the treatment of TBI, animal models of TBI should be established and standardized. In this study, we established mouse models of closed head injury using the Shohami weight-drop method with some modifications concerning cognitive deficiency assessment and provided a detailed description of the severe TBI animal model. We found that 250 g falling weight from 2 cm height produced severe closed head injury in C57BL/6 male mice. Cognitive disorders in mice with severe closed head injury could be detected using passive avoidance test on day 7 after injury. Findings from this study indicate that weight-drop injury animal models are suitable for further screening of brain neuroprotectants and potentially are similar to those seen in human TBI.

Suppressor of Cytokine Signaling-2 (SOCS2) Regulates the Microglial Response and Improves Functional Outcome after Traumatic Brain Injury in Mice

Traumatic brain injury (TBI) is frequently characterized by neuronal, axonal and myelin loss, reactive gliosis and neuroinflammation, often associated with functional deficits. Endogenous repair mechanisms include production of new neurons from precursor cells, but usually the new neurons fail to integrate and survive more than a few weeks. This is in part mediated by the toxic and inflammatory environment present in the injured brain which activates precursor cells to proliferate and differentiate but limits survival of the newborn progeny. Therefore, an understanding of mechanisms that regulate production and survival of newborn neurons and the neuroinflammatory response after brain injury may lead to therapeutic options to improve outcomes. Suppressor of Cytokine Signaling 2 (SOCS2) promotes hippocampal neurogenesis and survival of newborn neurons in the adult brain and regulates anti-inflammatory responses in the periphery, suggesting it may be a useful candidate to improve outcomes of TBI. In this study the functional and cellular responses of SOCS2 over-expressing transgenic (SOCS2Tg) mice were compared to wildtype littermates following mild or moderately severe TBI. Unlike wildtype controls, SOCS2Tg mice showed functional improvement on a ladder test, with a smaller lesion volume at 7d post injury and increased numbers of proliferative CD11b⁺ microglia/macrophages at 35d post-injury in the mild injury paradigm. At 7d post-moderately severe injury there was an increase in the area covered by cells expressing an anti-inflammatory M2 phenotype marker (CD206⁺) but no difference in cells with a pro-inflammatory M1 phenotype marker (CD16/32⁺). No effect of SOCS2 overexpression was observed in production or survival of newborn neurons, even in the presence of the neuroprotective agent erythropoietin (EPO). Therefore, SOCS2 may improve outcome of TBI in mice by regulating aspects of the neuroinflammatory response, promoting a more anti-inflammatory environment, although this was not sufficient to enhance survival of newborn cortical neurons.

Posttraining Epinephrine Reverses Memory Deficits Produced by Traumatic Brain Injury in Rats

The aim of this research is to evaluate whether posttraining systemic epinephrine is able to improve object recognition memory in rats with memory deficits produced by traumatic brain injury. Forty-nine two-month-old naïve male Wistar rats were submitted to surgical procedures to induce traumatic brain injury (TBI) or were sham-operated. Rats were trained in an object recognition task and, immediately after training, received an intraperitoneal injection of distilled water (Sham-Veh and TBI-Veh group) or 0.01 mg/kg epinephrine (TBI-Epi group) or no injection (TBI-0 and Sham-0 groups). Retention was tested 3 h and 24 h after acquisition. The results showed that brain injury produced severe memory deficits and that posttraining administration of epinephrine was able to reverse them. Systemic administration of distilled water also had an enhancing effect, but of a lower magnitude. These data indicate that posttraining epinephrine and, to a lesser extent, vehicle injection reduce memory deficits associated with TBI, probably through induction of a low-to-moderate emotional arousal.

Beneficial Effect of Erythropoietin Short Peptide on Acute Traumatic Brain Injury

There is currently no effective medical treatment for traumatic brain injury (TBI). Beyond the immediate physical damage caused by the initial impact, additional damage evolves due to the inflammatory response that follows brain injury. Here we show that therapy with JM4, a low molecular weight 19-amino acid nonhematopoietic erythropoietin (EPO) peptidyl fragment, containing amino acids 28-46 derived from the first loop of EPO, markedly reduces acute brain injury. Mice underwent controlled cortical injury and received either whole molecule EPO, JM4, or sham-treatment with phosphate-buffered saline. Animals treated with JM4 peptide exhibited a large decrease in number of dead neural cells and a marked reduction in lesion size at both 3 and 8 days postinjury. Therapy with JM4 also led to improved functional recovery and we observed a treatment window for JM4 peptide that remained open for at least 9 h postinjury. The full-length EPO molecule was divided into a series of 6 contiguous peptide segments; the JM4-containing segment and the adjoining downstream region contained the bulk of the death attenuating effects seen with intact EPO molecule following TBI. These findings indicate that the JM4 molecule substantially blocks cell death and brain injury following acute brain trauma and, as such, presents an excellent opportunity to explore the therapeutic potential of a small-peptide EPO derivative in the medical treatment of TBI.

Erythropoietin and Its Derivates Modulate Mitochondrial Dysfunction after Diffuse Traumatic Brain Injury

Inhibiting the opening of mitochondrial permeability transition pore (mPTP), thereby maintaining the mitochondrial membrane potential and calcium homeostasis, could reduce the induction of cell death. Although recombinant human erythropoietin (rhEpo) and carbamylated erythropoietin (Cepo) were shown to prevent apoptosis after traumatic brain injury (TBI), their impact on mPTP is yet unknown. Thirty minutes after diffuse TBI (impact-acceleration model), rats were intravenously administered a saline solution (TBI-saline), 5000 UI/kg rhEpo (TBI-rhEpo) or 50 μg/kg Cepo (TBI-Cepo). A fourth group received no TBI insult (sham-operated) (n = 11 rats per group). Post-traumatic brain edema was measured using magnetic resonance imaging. A first series of experiments was conducted 2 h after TBI (or equivalent) to investigate the mitochondrial function with the determination of thresholds for mPTP opening and ultrastructural mitochondrial changes. In addition, the intramitochondrial calcium content [Caim] was measured. In a second series of experiments, brain cell apoptosis was assessed at 24 h post-injury. TBI-rhEpo and TBI-Cepo groups had a reduced brain edema compared with TBI-saline. They had higher threshold for mPTP opening with succinate as substrate: 120 (120-150) (median, interquartiles) and 100 (100-120) versus 80 (60-90) nmol calcium/mg protein in TBI-saline, respectively (p < 0.05). Similar findings were shown with glutamate-malate as substrate. TBI-rhEpo and Cepo groups had less morphological mitochondrial disruption in astrocytes. The elevation in [Caim] after TBI was not changed by rhEpo and Cepo treatment. Finally, rhEpo and Cepo reduced caspase-3 expression at 24 h post-injury. These results indicate that rhEpo and Cepo could modulate mitochondrial dysfunction after TBI. The mechanisms involved are discussed.

Diffuse traumatic axonal injury in mice induces complex behavioural alterations that are normalized by neutralization of interleukin-1β

Widespread traumatic axonal injury (TAI) results in brain network dysfunction, which commonly leads to persisting cognitive and behavioural impairments following traumatic brain injury (TBI). TBI induces a complex neuroinflammatory response, frequently located at sites of axonal pathology. The role of the pro-inflammatory cytokine interleukin (IL)-1β has not been established in TAI. An IL-1β-neutralizing or a control antibody was administered intraperitoneally at 30 min following central fluid percussion injury (cFPI), a mouse model of widespread TAI. Mice subjected to moderate cFPI (n = 41) were compared with sham-injured controls (n = 20) and untreated, naive mice (n = 9). The anti-IL-1β antibody reached the target brain regions in adequate therapeutic concentrations (up to ~30 μg/brain tissue) at 24 h post-injury in both cFPI (n = 5) and sham-injured (n = 3) mice, with lower concentrations at 72 h post-injury (up to ~18 μg/g brain tissue in three cFPI mice). Functional outcome was analysed with the multivariate concentric square field (MCSF) test at 2 and 9 days post-injury, and the Morris water maze (MWM) at 14-21 days post-injury. Following TAI, the IL-1β-neutralizing antibody resulted in an improved behavioural outcome, including normalized behavioural profiles in the MCSF test. The performance in the MWM probe (memory) trial was improved, although not in the learning trials. The IL-1β-neutralizing treatment did not influence cerebral ventricle size or the number of microglia/macrophages. These findings support the hypothesis that IL-1β is an important contributor to the processes causing complex cognitive and behavioural disturbances following TAI.

Resveratrol attenuates neuronal autophagy and inflammatory injury by inhibiting the TLR4/NF-κB signaling pathway in experimental traumatic brain injury

Previous research has demonstrated that traumatic brain injury (TBI) activates autophagy and a neuroinflammatory cascade that contributes to substantial neuronal damage and behavioral impairment, and Toll-like receptor 4 (TLR4) is an important mediator of this cascade. In the present study, we investigated the hypothesis that resveratrol (RV), a natural polyphenolic compound with potent multifaceted properties, alleviates brain damage mediated by TLR4 following TBI. Adult male Sprague Dawley rats, subjected to controlled cortical impact (CCI) injury, were intraperitoneally injected with RV (100 mg/kg, daily for 3 days) after the onset of TBI. The results demonstrated that RV significantly reduced brain edema, motor deficit, neuronal loss and improved spatial cognitive function. Double immunolabeling demonstrated that RV decreased microtubule-associated protein 1 light chain 3 (LC3), TLR4‑positive cells co-labeled with the hippocampal neurons, and RV also significantly reduced the number of TLR4‑positive neuron‑specific nuclear protein (NeuN) cells following TBI. Western blot analysis revealed that RV significantly reduced the protein expression of the autophagy marker proteins, LC3II and Beclin1, in the hippocampus compared with that in the TBI group. Furthermore, the levels of TLR4 and its known downstream signaling molecules, nuclear factor-κB (NF-κB), and the inflammatory cytokines, interleukin (IL)-1β and tumor necrosis factor (TNF)-α were also decreased after RV treatment. Our results suggest that RV reduces neuronal autophagy and inflammatory reactions in a rat model of TBI. Thus, we suggest that the neuroprotective effect of RV is associated with the TLR4/NF-κB signaling pathway.

Therapies negating neuroinflammation after brain trauma

Traumatic brain injury (TBI) elicits a complex secondary injury response, with neuroinflammation as a crucial central component. Long thought to be solely a deleterious factor, the neuroinflammatory response has recently been shown to be far more intricate, with both beneficial and detrimental consequences depending on the timing, magnitude and specific immune composition of the response post-injury. Despite extensive preclinical and clinical research into mechanisms of secondary injury after TBI, no effective neuroprotective therapy has been identified, with potential candidates repeatedly proving disappointing in the clinic. The neuroinflammatory response offers a promising avenue for therapeutic targeting, aiming to quell the deleterious consequences without influencing its function in providing a neurotrophic environment supportive of repair. The present review firstly describes the findings of recent clinical trials that aimed to modulate inflammation as a means of neuroprotection. Secondly, we discuss promising multifunctional and single-target anti-inflammatory candidates either currently in trial, or with ample experimental evidence supporting clinical application. This article is part of a Special Issue entitled SI:Brain injury and recovery.

Mechanical stress models of Alzheimer's disease pathology

INTRODUCTION

Extracellular accumulation of amyloid-β protein and intracellular accumulation of tau in brain tissues have been described in animal models of Alzheimer's disease (AD) and mechanical stress-based diseases of different mechanisms, such as traumatic brain injury (TBI), arterial hypertension (HTN), and normal pressure hydrocephalus (NPH).

METHODS

We provide a brief overview of experimental models of TBI, HTN, and NPH showing features of tau-amyloid pathology, neuroinflammation, and neuronal loss.

RESULTS

"Alzheimer-like" hallmarks found in these mechanical stress-based models were compared with AD features found in transgenic models.

DISCUSSION

The goal of this review is, therefore, to build on current concepts of onset and progression of AD lesions. We point to the importance of accumulated mechanical stress in brain as an environmental and endogenous factor that pushes protein deposition and neuronal injury over the disease threshold. We further encourage the development of preventing strategies and drug screening based on mechanical stress models.

Erythropoietin in traumatic brain injury (EPO-TBI): a double-blind randomised controlled trial

BACKGROUND

Erythropoietin might have neurocytoprotective effects. In this trial, we studied its effect on neurological recovery, mortality, and venous thrombotic events in patients with traumatic brain injury.

METHODS

Erythropoietin in Traumatic Brain Injury (EPO-TBI) was a double-blind, placebo-controlled trial undertaken in 29 centres (all university-affiliated teaching hospitals) in seven countries (Australia, New Zealand, France, Germany, Finland, Ireland, and Saudi Arabia). Within 24 h of brain injury, 606 patients were randomly assigned by a concealed web-based computer-generated randomisation schedule to erythropoietin (40,000 units subcutaneously) or placebo (0·9% sodium chloride subcutaneously) once per week for a maximum of three doses. Randomisation was stratified by severity of traumatic brain injury (moderate vs severe) and participating site. With the exception of designated site pharmacists, the site dosing nurses at all sites, and the pharmacists at the central pharmacy in France, all study personnel, patients, and patients' relatives were masked to treatment assignment. The primary outcome, assessed at 6 months by modified intention-to-treat analysis, was improvement in the patients' neurological status, summarised as a reduction in the proportion of patients with an Extended Glasgow Outcome Scale (GOS-E) of 1-4 (death, vegetative state, and severe disability). Two equally spaced preplanned interim analyses were done (after 202 and 404 participants were enrolled). This study is registered with ClinicalTrials.gov, number NCT00987454.

FINDINGS

Between May 3, 2010, and Nov 1, 2014, 606 patients were enrolled and randomly assigned to erythropoietin (n=308) or placebo (n=298). Ten of these patients (six in the erythropoietin group and four in the placebo group) were lost to follow up at 6 months; therefore, data for the primary outcome analysis was available for 596 patients (302 in the erythropoietin group and 294 in the placebo group). Compared with placebo, erythropoietin did not reduce the proportion of patients with a GOS-E level of 1-4 (134 [44%] of 302 patients in the erythropoietin group vs 132 [45%] of 294 in the placebo group; relative risk [RR] 0·99 [95% CI 0·83-1·18], p=0·90). In terms of safety, erythropoietin did not significantly affect 6-month mortality versus placebo (32 [11%] of 305 patients had died at 6 months in the erythropoietin group vs 46 [16%] of 297 [16%] in the placebo group; RR 0·68 [95% CI 0·44-1·03], p=0·07) or increase the occurrence of deep venous thrombosis of the lower limbs (48 [16%] of 305 vs 54 [18%] of 298; RR 0·87 [95% CI 0·61-1·24], p=0·44).

INTERPRETATION

Following moderate or severe traumatic brain injury, erythropoietin did not reduce the number of patients with severe neurological dysfunction (GOS-E level 1-4) or increase the incidence of deep venous thrombosis of the lower limbs. The effect of erythropoietin on mortality remains uncertain.

FUNDING

The National Health and Medical Research Council and the Transport Accident Commission.

Neuroprotective potential of erythropoietin in neonates; design of a randomized trial

Background

In 2013, nearly four million babies were born in the U.S., among whom 447,875 were born preterm. Approximately 30,000 of these infants were born before 28 weeks of gestation. These infants, termed Extremely Low Gestational Age Neonates (ELGANs), experience high morbidity and mortality despite modern therapies: approximately 20 % of ELGANs admitted to an NICU die before discharge, 20 % of survivors have severe, and 20 % moderate neurodevelopmental impairment (NDI). New approaches are needed to improve neonatal outcomes. Recombinant erythropoietin (Epo) is a promising neuroprotective agent that is widely available, affordable, and has been used safely in neonates to stimulate erythropoiesis. There are extensive preclinical data to support its use as a neuroprotective intervention: Epo promotes normal brain maturation by increasing neurogenesis, angiogenesis, and by protecting oligodendrocytes. Epo also decreases acute brain injury following hypoxia ischemia by decreasing inflammation, oxidative and excitotoxic injury, resulting in decreased apoptosis. Despite the availability of both preclinical and safety data there has not been a definitive clinical evaluation of the benefit of Epo, and a large phase III trial is necessary to provide evidence to support potential changes in practice guidelines.

Findings

We first review the preclinical data motivating further clinical trials, and then describe in detail the design of the PENUT study (Preterm Epo Neuroprotection). PENUT is a phase III study evaluating the effect of neonatal Epo treatment on the combined outcome of death or severe NDI among ELGANS. 940 subjects will be randomized to determine: 1) whether Epo decreases the combined outcome of death or NDI at 22–26 months corrected age; 2) the safety of high dose Epo administration to ELGANs; 3) whether Epo treatment decreases serial measures of circulating inflammatory mediators, and improves biomarkers of brain injury; and 4) whether Epo treatment improves brain structure at 36 weeks postmenstrual age as measured by MRI.

Conclusions

Epo neuroprotection is an exciting new approach to preterm neuroprotection, and if efficacious, will provide a much-needed therapy for this group of vulnerable infants.