Therapeutic vaccination for closed head injury

Immune response after central nervous system injury

Traumatic injuries of the central nervous system (CNS) affect millions of people worldwide, and they can lead to severely damaging consequences such as permanent disability and paralysis. Multiple factors can obstruct recovery after CNS injury. One of the most significant is the progressive neuronal death that follows the initial mechanical impact, leading to the loss of undamaged cells via a process termed secondary neurodegeneration. Efforts to define treatments that limit the spread of damage, while important, have been largely ineffectual owing to gaps in the mechanistic understanding that underlies the persisting neuronal cell death. Inflammation, with its influx of immune cells that occurs shortly after injury, has been associated with secondary neurodegeneration. However, the role of the immune system after CNS injury is far more complex. Studies have indicated that the immune response after CNS injury is detrimental, owing to immune cell-produced factors (e.g., pro-inflammatory cytokines, free radicals, neurotoxic glutamate) that worsen tissue damage. Our lab and others have also demonstrated the beneficial immune response that occurs after CNS injury, with the release of growth factors such as brain-derived growth factor (BDNF) and interleukin (IL-10) and the clearance of apoptotic and myelin debris by immune cells^1-4. In this review, we first discuss the multifaceted roles of the immune system after CNS injury. We then speculate on how advancements in single-cell RNA technologies can dramatically change our understanding of the immune response, how the spinal cord meninges serve as an important site for hosting immunological processes critical for recovery, and how the origin of peripherally recruited immune cells impacts their function in the injured CNS.

Immunomodulation induced by central nervous system-related peptides as a therapeutic strategy for neurodegenerative disorders

Neurodegenerative diseases (NDD) are disorders characterized by the progressive loss of neurons affecting motor, sensory, and/or cognitive functions. The incidence of these diseases is increasing and has a great impact due to their high morbidity and mortality. Unfortunately, current therapeutic strategies only temporarily improve the patients' quality of life but are insufficient for completely alleviating the symptoms. An interaction between the immune system and the central nervous system (CNS) is widely associated with neuronal damage in NDD. Usually, immune cell infiltration has been identified with inflammation and is considered harmful to the injured CNS. However, the immune system has a crucial role in the protection and regeneration of the injured CNS. Nowadays, there is a consensus that deregulation of immune homeostasis may represent one of the key initial steps in NDD. Dr. Michal Schwartz originally conceived the concept of "protective autoimmunity" (PA) as a well-controlled peripheral inflammatory reaction after injury, essential for neuroprotection and regeneration. Several studies suggested that immunizing with a weaker version of the neural self-antigen would generate PA without degenerative autoimmunity. The development of CNS-related peptides with immunomodulatory neuroprotective effect led to important research to evaluate their use in chronic and acute NDD. In this review, we refer to the role of PA and the potential applications of active immunization as a therapeutic option for NDD treatment. In particular, we focus on the experimental and clinical promissory findings for CNS-related peptides with beneficial immunomodulatory effects.

Cellular and molecular pathophysiology in the progression of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder etiologically linked to the loss of substantia nigra (SN) dopaminergic neurons in the mid-brain. The etiopathology of sporadic PD is still unclear; however, the interaction of extrinsic and intrinsic factors may play a critical role in the onset and progression of the disease. Studies in animal models and human post-mortem tissue have identified distinct cellular and molecular changes in the diseased brain, suggesting complex interactions between different glial cell types and various molecular pathways. Small changes in the expression of specific genes in a single pathway or cell type possibly influence others at the cellular and system levels. These molecular and cellular signatures like neuroinflammation, oxidative stress, and autophagy have been observed in PD patients' brain tissue. While the etiopathology of PD is still poorly understood, the interplay between glial cells and molecular events may play a crucial role in disease onset and progression.

Aging and Neurodegenerative Disease: Is the Adaptive Immune System a Friend or Foe?

Neurodegenerative diseases of the central nervous system (CNS) are characterized by progressive neuronal death and neurological dysfunction, leading to increased disability and a loss of cognitive or motor functions. Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis have neurodegeneration as a primary feature. However, in other CNS diseases such as multiple sclerosis, stroke, traumatic brain injury, and spinal cord injury, neurodegeneration follows another insult, such as demyelination or ischaemia. Although there are different primary causes to these diseases, they all share a hallmark of neuroinflammation. Neuroinflammation can occur through the activation of resident immune cells such as microglia, cells of the innate and adaptive peripheral immune system, meningeal inflammation and autoantibodies directed toward components of the CNS. Despite chronic inflammation being pathogenic in these diseases, local inflammation after insult can also promote endogenous regenerative processes in the CNS, which are key to slowing disease progression. The normal aging process in the healthy brain is associated with a decline in physiological function, a steady increase in levels of neuroinflammation, brain shrinkage, and memory deficits. Likewise, aging is also a key contributor to the progression and exacerbation of neurodegenerative diseases. As there are associated co-morbidities within an aging population, pinpointing the precise relationship between aging and neurodegenerative disease progression can be a challenge. The CNS has historically been considered an isolated, "immune privileged" site, however, there is mounting evidence that adaptive immune cells are present in the CNS of both healthy individuals and diseased patients. Adaptive immune cells have also been implicated in both the degeneration and regeneration of the CNS. In this review, we will discuss the key role of the adaptive immune system in CNS degeneration and regeneration, with a focus on how aging influences this crosstalk.

How and why do T cells and their derived cytokines affect the injured and healthy brain?

The evolution of adaptive immunity provides enhanced defence against specific pathogens, as well as homeostatic immune surveillance of all tissues. Despite being 'immune privileged', the CNS uses the assistance of the immune system in physiological and pathological states. In this Opinion article, we discuss the influence of adaptive immunity on recovery after CNS injury and on cognitive and social brain function. We further extend a hypothesis that the pro-social effects of interferon-regulated genes were initially exploited by pathogens to increase host-host transmission, and that these genes were later recycled by the host to form part of an immune defence programme. In this way, the evolution of adaptive immunity may reflect a host-pathogen 'arms race'.

Expression of aryl hydrocarbon receptor in rat brain lesions following traumatic brain injury

Background

Aryl Hydrocarbon Receptor (AhR) is a ligand-activated transcription factor with multiple functions operating in a variety of organs, including the brain. Recent studies have revealed that AhR played a functional role in traumatic injuries. This paper aims to study the expression of AhR during the early phase following a traumatic brain injury (TBI) in rat brains by immunohistochemistry.

Methods

Weight-drop induced TBI was performed in rats. The expression of AhR in brain of TBI rats were examined by immunohistochemistry.

Results

Neuron expression of AhR in the rat brains of experiment group had been upregulated since day 3 in lesional hemisphere compared to that of the control group and mainly located in the cytoplasm, indicating an inactivated state. Interestingly, the accumulation of AhR⁺ non-neuron cells became significant as early as 18 h after injury, which had kept increasing until 24 h post injury and then decreased slowly. For AhR⁺ non-neuron cells, the AhR mainly located in cell nucleus, indicating a reactive status. Furthermore, double staining showed that most AhR⁺ non-neuron cells co-localized with W3/13, a marker for T lymphocytes, but not with ED-1 (for activated microglia/macrophages) or GFAP (for activated astrocytes), suggesting that most AhR⁺ non-neuron cells were T lymphocytes.

Conclusion

This is the first study concerning AhR expression in brains following TBI, and our data demonstrated that AhR was upregulated and activated in T lymphocytes following TBI. More research is needed to make a more conclusive conclusion.

Long-term production of BDNF and NT-3 induced by A91-immunization after spinal cord injury

BACKGROUND

After spinal cord (SC)-injury, a non-modulated immune response contributes to the damage of neural tissue. Protective autoimmunity (PA) is a T cell mediated, neuroprotective response induced after SC-injury. Immunization with neural-derived peptides (INDP), such as A91, has shown to promote-in vitro-the production of neurotrophic factors. However, the production of these molecules has not been studied at the site of injury.

RESULTS

In order to evaluate these issues, we performed four experiments in adult female Sprague-Dawley rats. In the first one, brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) concentrations were evaluated at the site of lesion 21 days after SC-injury. BDNF and NT-3 were significantly increased in INDP-treated animals. In the second experiment, proliferation of anti-A91 T cells was assessed at chronic stages of injury. In this case, we found a significant proliferation of these cells in animals subjected to SC-injury + INDP. In the third experiment, we explored the amount of BDNF and NT3 at the site of injury in the chronic phase of rats subjected to either SC-contusion (SCC; moderate or severe) or SC-transection (SCT; complete or incomplete). The animals were treated with INDP immediately after injury. Rats subjected to moderate contusion or incomplete SCT showed significantly higher levels of BDNF and NT-3 as compared to PBS-immunized ones. In rats with severe SCC and complete SCT, BDNF and NT-3 concentrations were barely detected. Finally, in the fourth experiment we assessed motor function recovery in INDP-treated rats with moderate SC-injury. Rats immunized with A91 showed a significantly higher motor recovery from the first week and up to 4 months after SC-injury.

CONCLUSIONS

The results of this study suggest that PA boosted by immunization with A91 after moderate SC-injury can exert its benefits even at chronic stages, as shown by long-term production of BDNF and NT-3 and a substantial improvement in motor recovery.

Traumatic brain injury using mouse models

The use of mouse models in traumatic brain injury (TBI) has several advantages compared to other animal models including low cost of breeding, easy maintenance, and innovative technology to create genetically modified strains. Studies using knockout and transgenic mice demonstrating functional gain or loss of molecules provide insight into basic mechanisms of TBI. Mouse models provide powerful tools to screen for putative therapeutic targets in TBI. This article reviews currently available mouse models that replicate several clinical features of TBI such as closed head injuries (CHI), penetrating head injuries, and a combination of both. CHI may be caused by direct trauma creating cerebral concussion or contusion. Sudden acceleration-deceleration injuries of the head without direct trauma may also cause intracranial injury by the transmission of shock waves to the brain. Recapitulation of temporary cavities that are induced by high-velocity penetrating objects in the mouse brain are difficult to produce, but slow brain penetration injuries in mice are reviewed. Synergistic damaging effects on the brain following systemic complications are also described. Advantages and disadvantages of CHI mouse models induced by weight drop, fluid percussion, and controlled cortical impact injuries are compared. Differences in the anatomy, biomechanics, and behavioral evaluations between mice and humans are discussed. Although the use of mouse models for TBI research is promising, further development of these techniques is warranted.

The role of glutamate and the immune system in organophosphate-induced CNS damage

Organophosphate (OP) poisoning is associated with long-lasting neurological damage, which is attributed mainly to the excessive levels of glutamate caused by the intoxication. Glutamate toxicity, however, is not specific to OP poisoning, and is linked to propagation of damage in both acute and chronic neurodegenerative conditions in the central nervous system (CNS). In addition to acute excitotoxic effects of glutamate, there is now a growing amount of evidence of its intricate immunomodulatory effects in the brain, involving both the innate and the adaptive immune systems. Moreover, it was demonstrated that immunomodulatory treatments, aimed at regulating the interaction between the resident immune cells of the brain (microglia) and the peripheral immune system, can support buffering of excessive levels of glutamate and restoration of the homeostasis. In this review, we will discuss the role of glutamate as an excitotoxic agent in the acute phase of OP poisoning, and the possible functions it may have as both a neuroprotectant and an immunomodulator in the sub-acute and chronic phases of OP poisoning. In addition, we will describe the novel immune-based neuroprotective strategies aimed at counteracting the long-term neurodegenerative effects of glutamate in the CNS.

Challenging the role of adaptive immunity in neurotrauma: Rag1(-/-) mice lacking mature B and T cells do not show neuroprotection after closed head injury

The role of adaptive immunity in contributing to post-traumatic neuroinflammation and neuropathology after head injury remains largely unexplored. The present study was designed to investigate the pathophysiological sequelae of closed head injury in Rag1(-/-) mice devoid of mature B and T lymphocytes. C57BL/6 wild-type and Rag1(-/-) mice were subjected to experimental closed head injury, using a standardized weight-drop device. Outcome parameters consisted of neurological scoring, quantification of blood-brain barrier (BBB) function, measurement of inflammatory markers and mediators of apoptosis in serum and brain tissue, and assessment of neuronal cell death, astrogliosis, and tissue destruction. There was no difference between wild-type and Rag1(-/-) mice with regard to injury severity and neurological impairment for up to 7 days after head injury. The extent of BBB dysfunction was in a similar range for both groups. Quantification of complement activation fragments in serum revealed significantly attenuated C3a levels in Rag1(-/-) mice compared to wild-type animals. In contrast, the levels of pro- and anti-inflammatory cytokines and pro-apoptotic and anti-apoptotic mediators remained in a similar range for both groups, and the histological analysis of brain sections did not reveal a difference in reactive astrogliosis, tissue destruction, and neuronal cell death in Rag1(-/-) compared to wild-type mice. These findings suggest that adaptive immunity is not of crucial importance for initiating and sustaining the inflammatory neuropathology after closed head injury. The attenuated extent of post-traumatic complement activation seen in Rag1(-/-) mice implies a cross-talk between innate and adaptive immune responses, which requires further investigation in future studies.

Autoreactivity against myelin basic protein in patients with chronic paraplegia

INTRODUCTION

Previous studies have shown the existence of either cellular or humoral MBP-reactive elements up to 5 years after spinal cord injury (SCI), but not the presence of both after 10 years.

MATERIALS AND METHODS

Twelve SCI patients, with more than 10 years of evolution, and 18 healthy blood donors were studied. Lymphocyte proliferation (colorimetric-BrdU ELISA assay) and antibody titers against MBP (ELISA Human IgG MBP-specific assay) were assessed.

RESULTS

SCI patients presented a significant T-cell proliferation against MBP (lymphocyte proliferation index: 3.7 ± 1.5, mean ± SD) compared to control individuals (0.7 ± 0.3; P < 0.001). Humoral response analysis yielded a significant difference (P < 0.0001) between the antibody titers of controls and SCI patients. A significant correlation between cellular and humoral responses was observed. Finally, patients with an ASIA B presented the highest immune responses.

CONCLUSION

This work demonstrates, for the first time, the existence of both cellular and humoral responses against MBP in the chronic stages (>10 years) of injury.

Both MHC and non-MHC genes regulate inflammation and T-cell response after traumatic brain injury

Genetic regulation of autoimmune neuroinflammation is a well known phenomenon, but genetic influences on inflammation following traumatic nerve injuries have received little attention. In this study we examined the inflammatory response in a rat traumatic brain injury (TBI) model, with a particular focus on major histocompatibility class II (MHC II) presentation, in two inbred rat strains that have been extensively characterized in experimental autoimmune encephalomyelitis (EAE); DA and PVG. In addition, MHC and Vra4 congenic strains on these backgrounds were studied to give information on MHC and non-MHC gene contribution. Thus, allelic differences in Vra4, harboring the Ciita gene, was found to regulate expression of the invariant chain at the mRNA level, with a much smaller effect exerted by the MHC locus itself. Notably, however, at the protein level the MHC congenic PVG-RT1(av1) strain displayed much stronger MHCII(+) presentation, as shown both by immunolabeling and flow cytometry, than the PVG strain, dwarfing the effect of Ciita. The PVG-RT1(av1) strain had significantly more T-cell influx than both DA and PVG, suggesting regulation both by MHC and non-MHC genes. Finally, in terms of outcome, the EAE susceptible DA strain displayed a significantly smaller resulting lesion volume than the resistant PVG-RT1(av1) strain. These results provide additional support for a role of adaptive immune response after neurotrauma and demonstrate that outcome is significantly affected by host genetic factors.

Mouse closed head injury model induced by a weight-drop device

Traumatic brain injury represents the leading cause of death in young individuals. Various animal models have been developed to mimic human closed head injury (CHI). Widely used models induce head injury by lateral fluid percussion, a controlled cortical impact or impact acceleration. The presented model induces a CHI by a standardized weight-drop device inducing a focal blunt injury over an intact skull without pre-injury manipulations. The resulting impact triggers a profound neuroinflammatory response within the intrathecal compartment with high consistency and reproducibility, leading to neurological impairment and breakdown of the blood-brain barrier. In this protocol, we define standardized procedures for inducing CHI in mice and determine various severity grades of CHI through modulation of the weight falling height. In experienced hands, this CHI model can be carried out in as little as 30 s per animal, with additional time required for subsequent posttraumatic analysis and data collection.

Protective autoimmunity in the nervous system

The immune system can play both detrimental and beneficial roles in the nervous system. Multiple arms of the immune system, including T cells, B cells, NK cells, mast cells, macrophages, dendritic cells, microglia, antibodies, complement and cytokines participate in limiting damage to the nervous system during toxic, ischemic, hemorrhagic, infective, degenerative, metabolic and immune-mediated insults and also assist in the process of repair after injury has occurred. Immune cells have been shown to produce neurotrophic growth factors and interact with neurons and glial cells to preserve them from injury and stimulate growth and repair. The immune system also appears to participate in proliferation of neural progenitor stem cells and their migration to sites of injury. Neural stem cells can also modify the immune response in the central and peripheral nervous system to enhance neuroprotective effects. Evidence for protective and reparative functions of the immune system has been found in diverse neurologic diseases including traumatic injury, ischemic and hemorrhagic stroke, multiple sclerosis, infection, and neurodegenerative diseases (Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis). Existing therapies including glatiramer acetate, interferon-beta and immunoglobulin have been shown to augment the protective and regenerative aspects of the immune system in humans, and other experimental interventions such as vaccination, minocycline, antibodies and neural stem cells, have shown promise in animal models of disease. The beneficent aspects of the immune response in the nervous system are beginning to be appreciated and their potential as pharmacologic targets in neurologic disease is being explored.

Modulation of innate immunity by copolymer-1 leads to neuroprotection in murine HIV-1 encephalitis

Virus-infected and immune-competent mononuclear phagocytes (MP; perivascular macrophages and microglia) drive the neuropathogenesis of human immunodeficiency virus type 1 (HIV-1) infection. Modulation of the MP phenotype from neurodestructive to neuroprotective underlies adjunctive therapeutic strategies for human disease. We reasoned that, as Copolymer-1 (Cop-1) can induce neuroprotective activities in a number of neuroinflammatory and neurodegenerative disorders, it could directly modulate HIV-1-infected MP neurotoxic activities. We now demonstrate that, in laboratory assays, Cop-1-stimulated virus-infected human monocyte-derived macrophages (MDM) protect against neuronal injury. Severe combined immune-deficient (SCID) mice were stereotactically injected with HIV-1-infected human MDM, into the basal ganglia, to induce HIV-1 encephalitis (HIVE). Cop-1 was administered subcutaneously for 7 days. In HIVE mice, Cop-1 treatment led to anti-inflammatory and neuroprotective responses. Reduced micro- and astrogliosis, and conserved NeuN/MAP-2 levels were observed in virus-affected brain regions in Cop-1-treated mice. These were linked to interleukin-10 and brain-derived neurotrophic factor expression and downregulation of inducible nitric oxide synthase. The data, taken together, demonstrate that Cop-1 can modulate innate immunity and, as such, improve disease outcomes in an animal model of HIVE.

T cell independent mechanism for copolymer-1-induced neuroprotection

Despite active investigation of copolymer-1 (Cop-1) for nearly 40 years the mechanisms underlying its neuroprotective properties remain contentious. Nonetheless, current dogma for Cop-1 neuroprotective activities in autoimmune and neurodegenerative diseases include bystander suppression of autoimmune T cells and attenuation of microglial responses. In this report, we demonstrate that Cop-1 interacts directly with primary human neurons and decreases neuronal cell death induced by staurosporine or oxidative stress. This neuroprotection is mediated through protein kinase Calpha and brain-derived neurotrophic factor. Dendritic cells (DC) uptake Cop-1, deliver it to the injury site, and release it in an active form. Interactions between Cop-1 and DC enhance DC blood brain barrier migration. In a rat model with optic nerve crush injury, Cop-1-primed DC induce T cell independent neuroprotection. These findings may facilitate the development of neuroprotective approaches using DC-mediated Cop-1 delivery to diseased nervous tissue.

Copolymer-1 (Cop-1) improves neurological recovery after middle cerebral artery occlusion in rats

The damage in ischemic stroke is caused by two events: (i) the ischemic phenomenon by itself; (ii) the self-destructive mechanisms developed as a consequence of ischemia. The inflammatory response is one of these destructive phenomena that accompanies and exacerbates the developing injury. Since it has been suggested that immune cells participate in neuroprotective and restorative processes, modulation rather than elimination of this inflammatory response could be a strategy to improve the neurological outcome. The immune modulator copolymer-1 (Cop-1), a synthetic basic random copolymer of amino acids, is a potent inducer of Th2 regulatory cells which, aside from exerting modulatory actions, is capable of releasing neurotrophic factors. There is evidence that Cop-1-specific T cells exert neuroprotective and even restorative effects in diverse neurodegenerative diseases. In order to test the ability of Cop-1 to prevent ischemic injury in a model of transient middle cerebral artery (MCA) occlusion, two groups of rats were treated either with Cop-1 or with saline solution (SS). Seven days after occlusion, Cop-1 treated rats presented a significant improvement in neurological function compared to SS-treated animals (1.2+/-0.4 and 2.8+/-0.5 mean+/-S.D., respectively; p=0.008). Histological findings showed that the percentage of infarct volume was smaller in Cop-1 treated rats (4.8+/-1.5), in comparison with those receiving SS (32.2+/-8.6; p=0.004). Cop-1 constitutes a promising therapy for stroke; thereby, the enforcement of further experimental investigation is encouraged in order to be able to formulate the best strategy.

Therapeutic vaccination for central nervous system repair

1. Vaccination against infectious agents has been heralded as a triumph in modern medicine and, more recently, cancer vaccines have risen in prominence. The present review looks towards the use of vaccine therapy to attenuate damage after injury to the central nervous system (CNS). 2. Significant debility is associated with brain injury, most commonly occurring as a result of physical trauma or stroke. This end result reflects the inability of neurons and axons to regenerate following injury to the CNS. This unconductive environment is due, in large part, to the presence of myelin and oligodendrocyte-related inhibitors of neurite outgrowth. 3. We review how a vaccine-based approach has been variably used to circumvent this issue and promote axonal regeneration and repair following traumatic injury and other neurodegenerative disorders. In addition, emerging evidence suggests that the immune response to injury in the CNS may be manipulated so as to reduce cellular damage. Vaccine-directed approaches using this concept are also outlined.

A Novel Immune-Based Therapy for Stroke Induces Neuroprotection and Supports Neurogenesis

The ability of the central nervous system to cope with stressful conditions was shown to be dependent on proper T-cell–mediated immune response. Because the therapeutic window for neuroprotection after acute insults such as stroke is relatively narrow, we searched for a procedure that would allow the relevant T cells to be recruited rapidly. Permanent middle cerebral artery occlusion was induced in adult rats. To facilitate a rapid poststroke T cell activity, rats were treated with poly-YE using different regimens. Control and poly-YE–treated rats were assessed for functional recovery using neurological severity score and Morris water maze. Neuroprotection, neurogenesis, growth factor expression, and microglial phenotype were assessed using histological and immunofluorescence methods. Administration of poly-YE as late as 24 hours after middle cerebral artery occlusion yielded a beneficial effect manifested by better neurological performance, reduced neuronal loss, attenuation of behavioral deficits, and increased hippocampal and cortical neurogenesis. This compound affected the subacute phase by modulating microglial response and by increasing local production of insulin-like growth factor-I, known to be a key player in neuronal survival and neurogenesis. The relative wide therapeutic window, coupled with its efficacy in attenuating further degeneration and enhancing restoration, makes poly-YE a promising immune-based candidate for stroke therapy.

The effect of traumatic brain injury upon the concentration and expression of interleukin-1beta and interleukin-10 in the rat

BACKGROUND

Using a model of traumatic brain injury (TBI) in the rat, this study was undertaken to characterize the short-term biochemical changes of IL-1beta, IL-10, and tumor necrosis factor TNF-alpha to determine whether injury in the brain elicits a systemic cytokine response.

METHODS

Sprague-Dawley rats were subjected to a TBI using a weight-drop model and then killed at various time points after injury. Samples of blood, brain, and liver were recovered and analyzed for concentrations of IL-1beta, IL-10, and TNF-alpha as well as IL-1beta and IL-10 mRNA expression in liver and brain.

RESULTS

In brain, IL-1beta increased in the first hour after injury, peaked at 8 hours, and declined during the final 16 hours. IL-10 quickly increased during the first 4 hours and then gradually rose over the last 20 hours. Analysis of liver showed no upregulation of these markers and plasma IL-1beta and IL-10 were unchanged compared with controls. Although not upregulated in brain, TNF-alpha showed a statistically significant (p < 0.05) rise in plasma from 14 +/- 16 pg/mL at 20 minutes to 91 +/- 28 pg/mL at 24 hours.

CONCLUSION

Using a model of TBI, we have demonstrated that there is a rise in both IL-1beta and IL-10 in the injured rat brain within the first 24 hours after injury without a corresponding rise in either plasma or liver. Therefore, it appears as if two strong indicators of brain injury severity are expressed and possibly carry out their actions solely in the brain.

Mononuclear phagocytes in the pathogenesis of neurodegenerative diseases

Brain mononuclear phagocytes (MP, bone marrow monocyte-derived macrophages, perivascular macrophages, and microglia) function to protect the nervous system by acting as debris scavengers, killers of microbial pathogens, and regulators of immune responses. MP are activated by a variety of environmental cues and such inflammatory responses elicit cell injury and death in the nervous system. MP immunoregulatory responses include secretion of neurotoxic factors, mobilization of adaptive immunity, and cell chemotaxis. This incites tissue remodelling and blood-brain barrier dysfunction. As disease progresses, MP secretions engage neighboring cells in a vicious cycle of autocrine and paracrine amplification of inflammation leading to tissue injury and ultimately destruction. Such pathogenic processes tilt the balance between the relative production of neurotrophic and neurotoxic factors and to disease progression. The ultimate effects that brain MP play in disease revolves "principally" around their roles in neurodegeneration. Importantly, common functions of brain MP in neuroimmunity link highly divergent diseases (for example, human immunodeficiency virus type-one associated dementia, Alzheimer's disease and Parkinson's disease). Research into this process from our own laboratories and those of others seek to harness MP inflammatory processes with the intent of developing therapeutic interventions that block neurodegenerative processes and improve the quality of life in affected people.

Are neurodegenerative disorders systemic diseases? Outlook for future immune-based therapies

The prevalence of neurodegenerative diseases increases exponentially with age. Increasing life expectancies in Western countries have, therefore, been accompanied by a growing increase in the number of victims, and in the future we can expect to see an increased number of the geriatric population suffering from these diseases. Despite improvements in our understanding of the pathogeneses, the prospects for finding a cure remain bleak. Many questions remain unanswered: are we dealing with a family of diseases or with individual unrelated syndromes? Is there a systemic malfunction that operates via a common pathway but affects different tissues or organs in different individuals? How will the answers to these questions affect future therapy?

T-cell-based vaccination for morphological and functional neuroprotection in a rat model of chronically elevated intraocular pressure

Acute or chronic glaucoma is often associated with an increase in intraocular pressure (IOP). In many patients, however, therapeutic pressure reduction does not halt disease progression. Neuroprotection has been proposed as a complementary therapeutic approach. We previously demonstrated effective T-cell-based neuroprotection in experimental animals vaccinated with the synthetic copolymer glatiramer acetate (copolymer-1, Cop-1), a weak agonist of self-antigens. This study was undertaken to test different routes and modes of vaccination with Cop-1 as treatment modalities for protection against retinal ganglion cell (RGC) death caused by chronic elevation of IOP in rats, and to determine whether anatomical neuroprotection is accompanied by functional neuroprotection. In a chronic model of unilaterally high IOP, Cop-1 vaccination, with or without an adjuvant, protected rats against IOP-induced loss of RGCs by eliciting a systemic T-cell-mediated response capable of cross-reacting with self-antigens residing in the eye. In rats deprived of T cells, Cop-1 (unlike treatment with alpha2-adrenoreceptor agonists) was not protective of RGCs, substantiating the contention that its beneficial effect is not conferred directly but is T-cell-mediated. Pattern electroretinography provided evidence of functional protection. Thus, vaccination with adjuvant-free Cop-1 can protect RGCs from the consequences of elevated IOP in rats. This protection is manifested both morphologically and functionally. These findings can be readily implemented for the development of a therapeutic vaccination to arrest the progression of glaucoma.

Nasal vaccination with a proteosome-based adjuvant and glatiramer acetate clears beta-amyloid in a mouse model of Alzheimer disease

Amyloid beta-peptide (Abeta) appears to play a key pathogenic role in Alzheimer disease (AD). Immune therapy in mouse models of AD via Abeta immunization or passive administration of Abeta antibodies markedly reduces Abeta levels and reverses behavioral impairment. However, a human trial of Abeta immunization led to meningoencephalitis in some patients and was discontinued. Here we show that nasal vaccination with a proteosome-based adjuvant that is well tolerated in humans plus glatiramer acetate, an FDA-approved synthetic copolymer used to treat multiple sclerosis, potently decreases Abeta plaques in an AD mouse model. This effect did not require the presence of antibody, as it was observed in B cell-deficient (Ig mu-null) mice. Vaccinated animals developed activated microglia that colocalized with Abeta fibrils, and the extent of microglial activation correlated strongly with the decrease in Abeta fibrils. Activation of microglia and clearing of Abeta occurred with the adjuvant alone, although to a lesser degree. Our results identify a novel approach to immune therapy for AD that involves clearing of Abeta through the utilization of compounds that have been safely tested on or are currently in use in humans.

Lessons for Glaucoma From Other Neurodegenerative Diseases: Can One Treatment Suit Them All?*

The past decade has seen growing acceptance that glaucoma should be viewed as a slowly progressive neurodegenerative disease. According to this view, in glaucoma (as in other such diseases), whatever the primary risk factors, at any given time some neurons are still healthy but are threatened with destruction owing to the toxicity emanating from the degenerating neurons. It follows that any intervention that protects surviving neurons and rescues the marginally damaged ones should slow down progression of the disease. This novel view of glaucoma prompted scientists to compare glaucoma with other neurodegenerative diseases with respect to mediators of disease progression and ways in which the spread of damage, or 'secondary degeneration', can be attenuated. Studies of partial crush injury of the rat optic nerve, a model of secondary degeneration established in our laboratory, led us to conceptualize the 'enemy within' as a flood of neurotoxic self-compounds issuing from the degenerating nerve. With this model, pharmacological and molecular approaches were employed to identify and test potentially therapeutic neuroprotective compounds and methodologies, leading us ultimately to the serendipitous discovery of protective autoimmunity as the body's defense against destructive self-compounds. Mediators of self-perpetuating acute and chronic degeneration identified in the injured optic nerve were also detected in other sites of central nervous system (CNS) damage. This finding led scientists to screen drugs that had proven to be beneficial in other disease models for their use in glaucoma therapy. It also opened the way to studies of the direct effects of these toxic mediators on retinal ganglion cell survival and ways to prevent the degenerative outcome. Although no single model can fully simulate human glaucoma or any other neurodegenerative disease, the availability of different models of optic nerve damage and the similarity of findings in the optic nerve and in other parts of the CNS have led to significant progress toward development of a cure for glaucoma.

The influence of the peptide NAP on Mac-1-deficient mice following closed head injury

A single administration of the neuroprotective peptide NAP was previously shown to protect against death associated with closed head injury (CHI) and enhance recovery of the surviving mice. The protective effect was accompanied by down-regulation of the relative mRNA content of the complement receptor 3 (Mac-1, a marker for inflammation) as measured about a month after the injury. In contrast, the mRNA transcripts for activity-dependent neuroprotective protein (ADNP, the NAP containing protein) were shown to increase 29 days post CHI in the injured hemisphere of Mac-1 expressing mice. The present study was set out to investigate: (1) are Mac-1-deficient mice less susceptible to the adverse outcome of traumatic head injury; (2) does NAP treatment affect Mac-1-deficient mice subjected to head injury; and (3) is Mac-1 expression associated with ADNP expression. Results showed that (1) Mac-1-deficient mice were partially protected against death associated with severe head injury as compared to Mac-1 expressing mice. (2) Significant protection against death was observed in NAP-treated mice and an increase in recovery was observed in the NAP-treated Mac-1 mice 4 weeks after injury. (3) ADNP expression did not change in the Mac-1-deficient mice following head injury. Our working hypothesis is that a month following injury, gene expression in the injured brain is altered and competing proteins are expressed such as Mac-1 that is associated with inflammation and ADNP that is associated with neuroprotection. Obviously, this plasticity in gene expression is intimately interwoven with the genetic background of the animal. NAP treatment tilts the balance toward neuroprotection.

Traumatic brain injury: physiology, mechanisms, and outcome

PURPOSE OF REVIEW

This review on traumatic brain injury consolidates the substantial current literature available on the pathophysiology, mechanisms, developments, and their subsequent effects on outcome. In particular, it tries to conceptualize why our greatly improved understanding of pathophysiology and neurobiology in traumatic brain injury has not translated into clear outcome improvements.

RECENT FINDINGS

Early cerebral ischaemia has been characterized further, with ischaemic brain volume correlating with 6-month outcome. The Brain Trauma Foundation has revised perfusion pressure targets, and there are additional data on the outcome impact of brain tissue oxygen response and asymmetric patterns of cerebral autoregulation. Mechanistic studies have highlighted the role of inflammation and introduced concepts such as therapeutic vaccination and immune modulation. Experimental neurogenesis and repair strategies show promise. Despite continuing gains in knowledge, the experimental successes have not yet translated to the clinic. Indeed, several major articles have attempted to understand the clinical failure of highly promising strategies such as hypothermia, and set out the framework for further studies (e.g. addressing decompressive craniectomy). High-dose mannitol has shown promise in poor grade patients, while hypertonic saline has shown better intracranial pressure control. Negative results may be the consequence of ineffective therapies. However, there is a gathering body of work that highlights the outcome impact of subtle neurocognitive changes, which may not be quantified adequately by outcome measures used in previous trials. Such knowledge has also informed improved definition of mild traumatic brain injury, and allowed validation of management guidelines.

SUMMARY

The evidence base for current therapies in this heterogeneous patient group is being refined, with greater emphasis on long-term functional outcomes. Improved monitoring techniques emphasize the need for individualization of therapeutic interventions.

A common vaccine for fighting neurodegenerative disorders: recharging immunity for homeostasis

Neurodegenerative conditions share common primary risk factors and mediators of disease progression. Because many degenerative disorders are age related, deteriorating immunity in aging patients might impose additional risk. Adaptive (T-cell-mediated) immunity is a defense mechanism that instructs microglia to fight off and clear away self-derived enemies. Such adaptive immunity can be boosted, without risking the development of autoimmune disease, by injecting weak agonists of self-antigens or by weakening the suppressive CD4+CD25+ regulatory T cells. If widely cross-reactive, the agonist might effectively counteract a variety of neurodegenerative disorders. Boosting of relevant T cells by vaccination could thus "recharge" a deteriorating immune system that has to contend with an increasing number of risk factors.

T cell deficiency leads to cognitive dysfunction: implications for therapeutic vaccination for schizophrenia and other psychiatric conditions

The effects of the adaptive immune system on the cognitive performance and abnormal behaviors seen in mental disorders such as schizophrenia have never been documented. Here, we show that mice deprived of mature T cells manifested cognitive deficits and behavioral abnormalities, which were remediable by T cell restoration. T cell-based vaccination, using glatiramer acetate (copolymer-1, a weak agonist of numerous self-reactive T cells), can overcome the behavioral and cognitive abnormalities that accompany neurotransmitter imbalance induced by (+)dizocilpine maleate (MK-801) or amphetamine. The results, by suggesting that peripheral T cell deficit can lead to cognitive and behavioral impairment, highlight the importance of properly functioning adaptive immunity in the maintenance of mental activity and in coping with conditions leading to cognitive deficits. These findings point to critical factors likely to contribute to age- and AIDS-related dementias and might herald the development of a therapeutic vaccination for fighting off cognitive dysfunction and psychiatric conditions.