COG1410 improves cognitive performance and reduces cortical neuronal loss in the traumatically injured brain

COG1410 regulates microglial states and protects retinal ganglion cells in retinal ischemia-reperfusion injury

Progressive loss of retinal ganglion cells (RGCs) caused by retinal ischemia-reperfusion (IR) injury can lead to irreversible vision impairment, with neuroinflammatory responses playing an important role in this process. COG1410, a mimetic peptide of apolipoprotein E, has demonstrated protective potential in the central nervous system, but its effects on retinal IR injury remain unexplored. In this study, we established a mouse model of retinal IR injury to investigate the effects of COG1410 on retinal microglia and RGCs. We observed CD16/32-marked and CD206-marked microglia and RGCs using immunofluorescence staining, detected the expression of inflammatory factors by PCR, and evaluated retinal apoptosis with TUNEL staining. We further investigated the potential mechanism by detecting the expression of key proteins via Western blot. The results reveal that COG1410 decreased the number of CD16/32-marked microglia and increased the number of CD206-marked microglia, alleviated the expression of IL-1β and TNF-α, and reduced the loss of RGCs by inhibiting the mitochondrial-related apoptotic pathway. COG1410 was found to increase the expression of ERK1/2 and Nr4a1 but decrease the expression of NF-κB. The expression of TREM2 showed an increasing trend after COG1410 administration, but it was not statistically significant. In conclusion, COG1410 regulates microglial states and protects RGCs in retinal IR injury, showing promising potential for the treatment of eye diseases.

ApoE Mimetic Peptides as Therapy for Traumatic Brain Injury

The lack of targeted therapies for traumatic brain injury (TBI) remains a compelling clinical unmet need. Although knowledge of the pathophysiologic cascades involved in TBI has expanded rapidly, the development of novel pharmacological therapies has remained largely stagnant. Difficulties in creating animal models that recapitulate the different facets of clinical TBI pathology and flaws in the design of clinical trials have contributed to the ongoing failures in neuroprotective drug development. Furthermore, multiple pathophysiological mechanisms initiated early after TBI that progress in the subacute and chronic setting may limit the potential of traditional approaches that target a specific cellular pathway for acute therapeutic intervention. We describe a reverse translational approach that focuses on translating endogenous mechanisms known to influence outcomes after TBI to develop druggable targets. In particular, numerous clinical observations have demonstrated an association between apolipoprotein E (apoE) polymorphism and functional recovery after brain injury. ApoE has been shown to mitigate the response to acute brain injury by exerting immunomodulatory properties that reduce secondary tissue injury as well as protecting neurons from excitotoxicity. CN-105 represents an apoE mimetic peptide that can effectively penetrate the CNS compartment and retains the neuroprotective properties of the intact protein.

Combining tissue clearing and Fluoro-Jade C labeling for neurotoxicity assessments

Tissue clearing refers to laboratory methods that make tissue transparent by chemical means. This approach allows the labeling, visualization, and analysis of specific targets without cutting the tissue into sections, thereby maintaining three-dimensional architecture. More than two dozen tissue-clearing methods have been developed by different research teams to date. While tissue clearing has been successfully applied in several studies concerning basic science or diseases, little is known about the utilization of tissue clearing for neurotoxicity evaluation. In this study, several tissue-clearing methods were combined with Fluoro-Jade C (FJ-C), a standard marker of neurodegeneration. The results suggest that some but not all tissue-clearing media are compatible with the FJ-C fluorophore. By utilizing a neurotoxicity animal model, the results further suggest that FJ-C labeling can be combined with tissue clearing for neurotoxicity assessments. This approach has the potential to be expanded further by combining multicolor labeling of molecular targets involved in the development and/or mechanisms of neurotoxicity and neurodegeneration.

Apolipoprotein E mimetic peptide COG1410 alleviates blood‑brain barrier injury in a rat model of ischemic stroke

Blood‑brain barrier (BBB) damage is one of the main causes of poor outcomes and increased mortality rates following cerebral ischemia‑reperfusion injury. Apolipoprotein E (ApoE) and its mimetic peptide have been previously reported to exhibit potent neuroprotective properties in various central nervous system disease models. Therefore, the present study aimed to investigate the possible role of the ApoE mimetic peptide COG1410 in cerebral ischemia‑reperfusion injury and its potential underlying mechanism. Male SD rats were subjected to 2 h middle cerebral artery occlusion followed by 22 h reperfusion. Evans blue leakage and IgG extravasation assays results revealed that COG1410 treatment significantly reduced BBB permeability. In addition, in situ zymography and western blotting were used to prove that COG1410 was able to downregulate the activities of MMPs and upregulate the expression of occludin in the ischemic brain tissue samples. Subsequently, COG1410 was found to significantly reverse microglia activation while also suppressing inflammatory cytokine production, according to immunofluorescence signal of Iba‑1 and CD68 and protein expression of COX‑2. Consequently, this neuroprotective mechanism mediated by COG1410 was further tested using the BV2 cell line in vitro, which was exposed to oxygen glucose deprivation followed by reoxygenation. The mechanism of COG1410 was found to be mediated, as least partly, through the activation of triggering receptor expressed on myeloid cells 2. In conclusion, the data suggest that COG1410 can alleviate BBB injury and neuroinflammation following ischemic stroke.

Prophylactic treatment with CN-105 improves functional outcomes in a murine model of closed head injury

The treatment of traumatic brain injury (TBI) in military populations is hindered by underreporting and underdiagnosis. Clinical symptoms and outcomes may be mitigated with an effective pre-injury prophylaxis. This study evaluates whether CN-105, a 5-amino acid apolipoprotein E (ApoE) mimetic peptide previously shown to modify the post-traumatic neuroinflammatory response, would maintain its neuroprotective effects if administered prior to closed-head injury in a clinically relevant murine model. CN-105 was synthesized by Polypeptide Inc. (San Diego, CA) and administered to C57-BL/6 mice intravenously (IV) and/or by intraperitoneal (IP) injection at various time points prior to injury while vehicle treated animals received IV and/or IP normal saline. Animals were randomized following injury and behavioral observations were conducted by investigators blinded to treatment. Vestibulomotor function was assessed using an automated Rotarod (Ugo Basile, Comerio, Italy), and hippocampal microglial activation was assessed using F4/80 immunohistochemical staining in treated and untreated mice 7 days post-TBI. Separate, in vivo assessments of the pharmacokinetics was performed in healthy CD-1. IV CN-105 administered prior to head injury improved vestibulomotor function compared to vehicle control-treated animals. CN-105 co-administered by IP and IV dosing 6 h prior to injury also improved vestibulomotor function up to 28 days following injury. Microglia counted in CN-105 treated specimens were significantly fewer (P = 0.03) than in vehicle specimens. CN-105 improves functional outcomes and reduces hippocampal microglial activation when administered prior to injury and could be adapted as a pre-injury prophylaxis for soldiers at high risk for TBI.

CN-105 in Participants with Acute Supratentorial Intracerebral Hemorrhage (CATCH) Trial

BACKGROUND

Endogenous apolipoprotein (apo) E mediates neuroinflammatory responses and recovery after brain injury. Exogenously administered apoE-mimetic peptides effectively penetrate the central nervous system compartment and downregulate acute inflammation. CN-105 is a novel apoE-mimetic pentapeptide with excellent evidence of functional and histological improvement in preclinical models of intracerebral hemorrhage (ICH). The CN-105 in participants with Acute supraTentorial intraCerebral Hemorrhage (CATCH) trial is a first-in-disease-state multicenter open-label trial evaluating safety and feasability of CN-105 administration in patients with acute primary supratentorial ICH.

METHODS

Eligible patients were aged 30-80 years, had confirmed primary supratentorial ICH, and were able to intiate CN-105 administration (1.0 mg/kg every 6 h for 72 h) within 12 h of symptom onset. A priori defined safety end points, including hematoma volume, pharmacokinetics, and 30-day neurological outcomes, were analyzed. For clinical outcomes, CATCH participants were compared 1:1 with a closely matched contemporary ICH cohort through random selection. Hematoma volumes determined from computed tomography images on days 0, 1, 2, and 5 and ordinal modified Rankin Scale score at 30 days after ICH were compared.

RESULTS

In 38 participants enrolled across six study sites in the United States, adverse events occurred at an expected rate without increase in hematoma expansion or neurological deterioration. CN-105 treatment had an odds ratio (95% confidence interval) of 2.69 (1.31-5.51) for lower 30-day modified Rankin Scale score, after adjustment for ICH score, sex, and race/ethnicity, as compared with a matched contemporary cohort.

CONCLUSIONS

CN-105 administration represents an excellent translational candidate for treatment of acute ICH because of its safety, dosing feasibility, favorable pharmacokinetics, and possible improvement in neurological recovery.

The Role of HDL and HDL Mimetic Peptides as Potential Therapeutics for Alzheimer's Disease

The role of high-density lipoproteins (HDL) in the cardiovascular system has been extensively studied and the cardioprotective effects of HDL are well established. As HDL particles are formed both in the systemic circulation and in the central nervous system, the role of HDL and its associated apolipoproteins in the brain has attracted much research interest in recent years. Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder and the leading cause of dementia worldwide, for which there currently exists no approved disease modifying treatment. Multiple lines of evidence, including a number of large-scale human clinical studies, have shown a robust connection between HDL levels and AD. Low levels of HDL are associated with increased risk and severity of AD, whereas high levels of HDL are correlated with superior cognitive function. Although the mechanisms underlying the protective effects of HDL in the brain are not fully understood, many of the functions of HDL, including reverse lipid/cholesterol transport, anti-inflammation/immune modulation, anti-oxidation, microvessel endothelial protection, and proteopathy modification, are thought to be critical for its beneficial effects. This review describes the current evidence for the role of HDL in AD and the potential of using small peptides mimicking HDL or its associated apolipoproteins (HDL-mimetic peptides) as therapeutics to treat AD.

TREM2 activation attenuates neuroinflammation and neuronal apoptosis via PI3K/Akt pathway after intracerebral hemorrhage in mice

BACKGROUND

Neuroinflammation is an important host defense response to secondary brain injury after intracerebral hemorrhage (ICH). Triggering receptor expressed on myeloid cells 2 (TREM2) confers strong neuroprotective effects by attenuating neuroinflammation in experimental ischemic stroke. Recent studies suggest that apolipoprotein E (apoE) is a novel, high-affinity ligand of TREM2. This study aimed to investigate the effects of TREM2 activation on neuroinflammation and neuronal apoptosis in a mouse model of ICH.

METHODS

Adult male CD1 mice (n = 216) were subjected to intrastriatal injection of bacterial collagenase. The TREM2 ligand, apoE-mimetic peptide COG1410 was administered intranasally at 1 h after ICH induction. To elucidate the underlying mechanism, TREM2 small interfering RNA (siRNA) and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 were administered intracerebroventricularly prior to COG1410 treatment. Neurobehavioral tests, brain water content, immunofluorescence, western blotting, and Fluoro-Jade C- and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were performed.

RESULTS

Endogenous TREM2 expression was increased and peaked at 24 h after ICH. TREM2 was expressed on microglia, astrocytes, and neurons. COG1410 improved both short-term and long-term neurological functions, reduced brain edema, inhibited microglia/macrophage activation and neutrophil infiltration, and suppressed neuronal apoptotic cell death in perihematomal areas after ICH. Knockdown of endogenous TREM2 by TREM2 siRNA aggravated neurological deficits and decreased the expression of TREM2 in naïve and ICH mice. COG1410 was associated with upregulation of TREM2, PI3K, phosphorylated-Akt, and Bcl-2 and downregulation of TNF-α, IL-1β, and Bax after ICH. The neuroprotective effects of COG1410 were abolished by both TREM2 siRNA and PI3K inhibitor LY294002.

CONCLUSIONS

Our finding demonstrated that TREM2 activation improved neurological functions and attenuated neuroinflammation and neuronal apoptosis after ICH, which was, at least in part, mediated by activation of PI3K/Akt signaling pathway. Therefore, activation of TREM2 may be a potential therapeutic strategy for the management of ICH patients.

Therapeutic Development of Apolipoprotein E Mimetics for Acute Brain Injury: Augmenting Endogenous Responses to Reduce Secondary Injury

Over the last few decades, increasing evidence demonstrates that the neuroinflammatory response is a double-edged sword. Although overly robust inflammatory responses may exacerbate secondary tissue injury, inflammatory processes are ultimately necessary for recovery. Traditional drug discovery often relies on reductionist approaches to isolate and modulate specific intracellular pathways believed to be involved in disease pathology. However, endogenous brain proteins are often pleiotropic in order to regulate neuroinflammation and recovery mechanisms. Thus, a process of "backward translation" aims to harness the adaptive properties of endogenous proteins to promote earlier and greater recovery after acute brain injury. One such endogenous protein is apolipoprotein E (apoE), the primary apolipoprotein produced in the brain. Robust preclinical and clinical evidence demonstrates that endogenous apoE produced within the brain modulates the neuroinflammatory response of the acutely injured brain. Thus, one innovative approach to improve outcomes following acute brain injury is administration of exogenous apoE-mimetic drugs optimized to cross the blood-brain barrier. In particular, one promising apoE mimetic peptide, CN-105, has demonstrated efficacy across a wide variety of preclinical models of brain injury and safety and feasibility in early-phase clinical trials. Preclinical and clinical evidence for apoE's neuroprotective effects and downregulation of neuroinflammatory and the resulting translational therapeutic development strategy for an apoE-based therapeutic are reviewed.

Cationic Arginine-Rich Peptides (CARPs): A Novel Class of Neuroprotective Agents With a Multimodal Mechanism of Action

There are virtually no clinically available neuroprotective drugs for the treatment of acute and chronic neurological disorders, hence there is an urgent need for the development of new neuroprotective molecules. Cationic arginine-rich peptides (CARPs) are an expanding and relatively novel class of compounds, which possess intrinsic neuroprotective properties. Intriguingly, CARPs possess a combination of biological properties unprecedented for a neuroprotective agent including the ability to traverse cell membranes and enter the CNS, antagonize calcium influx, target mitochondria, stabilize proteins, inhibit proteolytic enzymes, induce pro-survival signaling, scavenge toxic molecules, and reduce oxidative stress as well as, having a range of anti-inflammatory, analgesic, anti-microbial, and anti-cancer actions. CARPs have also been used as carrier molecules for the delivery of other putative neuroprotective agents across the blood-brain barrier and blood-spinal cord barrier. However, there is increasing evidence that the neuroprotective efficacy of many, if not all these other agents delivered using a cationic arginine-rich cell-penetrating peptide (CCPPs) carrier (e.g., TAT) may actually be mediated largely by the properties of the carrier molecule, with overall efficacy further enhanced according to the amino acid composition of the cargo peptide, in particular its arginine content. Therefore, in reviewing the neuroprotective mechanisms of action of CARPs we also consider studies using CCPPs fused to a putative neuroprotective peptide. We review the history of CARPs in neuroprotection and discuss in detail the intrinsic biological properties that may contribute to their cytoprotective effects and their usefulness as a broad-acting class of neuroprotective drugs.

S-Nitrosoglutathione Mimics the Beneficial Activity of Endothelial Nitric Oxide Synthase-Derived Nitric Oxide in a Mouse Model of Stroke

BACKGROUND

The nitric oxide (NO)-producing activity of endothelial nitric oxide synthase (eNOS) plays a significant role in maintaining endothelial function and protecting against the stroke injury. However, the activity of the eNOS enzyme and the metabolism of major NO metabolite S-nitrosoglutathione (GSNO) are dysregulated after stroke, causing endothelial dysfunction. We investigated whether an administration of exogenous of GSNO or enhancing the level of endogenous GSNO protects against neurovascular injury in wild-type (WT) and eNOS-null (endothelial dysfunction) mouse models of cerebral ischemia-reperfusion (IR).

METHODS

Transient cerebral ischemic injury was induced by middle cerebral artery occlusion (MCAO) for 60 minutes in male adult WT and eNOS null mice. GSNO (0.1 mg/kg body weight, intravenously) or N6022 (GSNO reductase inhibitor, 5.0 mg/kg body weight, intravenously) was administered 30 minutes before MCAO in preinjury and at the reperfusion in postinjury studies. Brain infarctions, edema, and neurobehavioral functions were evaluated at 24 hours after the reperfusion.

RESULTS

eNOS-null mice had a higher degree (P< .05) of injury than WT. Pre- or postinjury treatment with either GSNO or N6022 significantly reduced infarct volume, improved neurological and sensorimotor function in both WT and eNOS-null mice.

CONCLUSION

Reduced brain infarctions and edema, and improved neurobehavioral functions by pre- or postinjury GSNO treatment of eNOS knock out mice indicate that GSNO can attenuate IR injury, likely by mimicking the eNOS-derived NO-dependent anti-ischemic and anti-inflammatory functions. Neurovascular protection by GSNO/N6022 in both pre- and postischemic injury groups support GSNO as a promising drug candidate for the prevention and treatment of stroke injury.

Protein phosphatase 2A as a therapeutic target in inflammation and neurodegeneration

Protein phosphatase 2A (PP2A) is a highly complex heterotrimeric enzyme that catalyzes the selective removal of phosphate groups from protein serine and threonine residues. Emerging evidence suggests that it functions as a tumor suppressor by constraining phosphorylation-dependent signalling pathways that regulate cellular transformation and metastasis. Therefore, PP2A-activating drugs (PADs) are being actively sought and investigated as potential novel anti-cancer treatments. Here we explore the concept that PP2A also constrains inflammatory responses through its inhibitory effects on various signalling pathways, suggesting that PADs may be effective in the treatment of inflammation-mediated pathologies.

Assessment of R18, COG1410, and APP96-110 in Excitotoxicity and Traumatic Brain Injury

Cationic arginine-rich and poly-arginine peptides (referred to as CARPs) have potent neuroprotective properties in in vitro excitotoxicity and in vivo models of stroke. Traumatic brain injury (TBI) shares many pathophysiological processes as stroke, including excitotoxicity. Therefore, we evaluated our lead peptide, poly-arginine R18, with the COG1410 and APP96-110 peptides, which have neuroprotective actions following TBI. In an in vitro cortical neuronal glutamic acid excitotoxicity injury model, R18 was highly neuroprotective and reduced neuronal calcium influx, while COG1410 and APP96-110 displayed modest neuroprotection and were less effective at reducing calcium influx. In an impact-acceleration closed-head injury model (Marmarou model), R18, COG1410, and APP96-110 were administered intravenously (300 nmol/kg) at 30 minutes after injury in male Sprague-Dawley rats. When compared to vehicle, no peptide significantly improved functional outcomes, however the R18 and COG1410 treatment groups displayed positive trends in the adhesive tape test and rotarod assessments. Similarly, no peptide had a significant effect on hippocampal neuronal loss, however a significant reduction in axonal injury was observed for R18 and COG1410. In conclusion, this study has demonstrated that R18 is significantly more effective than COG1410 and APP96-110 at reducing neuronal injury and calcium influx following excitotoxicity, and that both R18 and COG1410 reduce axonal injury following TBI. Additional dose response and treatment time course studies are required to further assess the efficacy of R18 in TBI.

Apolipoprotein E as a novel therapeutic neuroprotection target after traumatic spinal cord injury

Apolipoprotein E (apoE), a plasma lipoprotein well known for its important role in lipid and cholesterol metabolism, has also been implicated in many neurological diseases. In this study, we examined the effect of apoE on the pathophysiology of traumatic spinal cord injury (SCI). ApoE-deficient mutant (apoE^-/-) and wild-type mice received a T9 moderate contusion SCI and were evaluated using histological and behavioral analyses after injury. At 3days after injury, the permeability of spinal cord-blood-barrier, measured by extravasation of Evans blue dye, was significantly increased in apoE^-/- mice compared to wild type. The inflammation and spared white matter was also significantly increased and decreased, respectively, in apoE^-/- mice compared to the wild type ones. The apoptosis of both neurons and oligodendrocytes was also significantly increased in apoE^-/- mice. At 42days after injury, the inflammation was still robust in the injured spinal cord in apoE^-/- but not wild type mice. CD45+ leukocytes from peripheral blood persisted in the injured spinal cord of apoE^-/- mice. The spared white matter was significantly decreased in apoE^-/- mice compared to wild type ones. Locomotor function was significantly decreased in apoE^-/- mice compared to wild type ones from week 1 to week 8 after contusion. Treatment of exogenous apoE mimetic peptides partially restored the permeability of spinal cord-blood-barrier in apoE^-/- mice after SCI. Importantly, the exogenous apoE peptides decreased inflammation, increased spared white matter and promoted locomotor recovery in apoE^-/- mice after SCI. Our results indicate that endogenous apoE plays important roles in maintaining the spinal cord-blood-barrier and decreasing inflammation and spinal cord tissue loss after SCI, suggesting its important neuroprotective function after SCI. Our results further suggest that exogenous apoE mimetic peptides could be a novel and promising neuroprotective reagent for SCI.

Neuroprotective pentapeptide CN-105 is associated with reduced sterile inflammation and improved functional outcomes in a traumatic brain injury murine model

At present, there are no proven pharmacological treatments demonstrated to improve long term functional outcomes following traumatic brain injury(TBI). In the setting of non-penetrating TBI, sterile brain inflammatory responses are associated with the development of cerebral edema, intracranial hypertension, and secondary neuronal injury. There is increasing evidence that endogenous apolipoprotein E(apoE) modifies the neuroinflammatory response through its role in downregulating glial activation, however, the intact apoE holoprotein does not cross the blood-brain barrier due to its size. To address this limitation, we developed a small 5 amino acid apoE mimetic peptide(CN-105) that mimics the polar face of the apoE helical domain involved in receptor interactions. The goal of this study was to investigate the therapeutic potential of CN-105 in a murine model of closed head injury. Treatment with CN-105 was associated with a durable improvement in functional outcomes as assessed by Rotarod and Morris Water Maze and a reduction in positive Fluoro-Jade B stained injured neurons and microglial activation. Administration of CN-105 was also associated with reduction in mRNA expression of a subset of inflammatory and immune-related genes.

Apolipoprotein E mimetic peptide, CN-105, improves outcomes in ischemic stroke

Objective

At present, the absence of a pharmacological neuroprotectant represents an important unmet clinical need in the treatment of ischemic and traumatic brain injury. Recent evidence suggests that administration of apolipoprotein E mimetic therapies represent a viable therapeutic strategy in this setting. We investigate the neuroprotective and anti‐inflammatory properties of the apolipoprotein E mimetic pentapeptide, CN‐105, in a microglial cell line and murine model of ischemic stroke.

Methods

Ten to 13‐week‐old male C57/BL6 mice underwent transient middle cerebral artery occlusion and were randomly selected to receive CN‐105 (0.1 mg/kg) in 100 μL volume or vehicle via tail vein injection at various time points. Survival, motor‐sensory functional outcomes using rotarod test and 4‐limb wire hanging test, infarct volume assessment using 2,3,5‐Triphenyltetrazolium chloride staining method, and microglial activation in the contralateral hippocampus using F4/80 immunostaining were assessed at various time points. In vitro assessment of tumor necrosis factor‐alpha secretion in a microglial cell line was performed, and phosphoproteomic analysis conducted to explore early mechanistic pathways of CN‐105 in ischemic stroke.

Results

Mice receiving CN‐105 demonstrated improved survival, improved functional outcomes, reduced infarct volume, and reduced microglial activation. CN‐105 also suppressed inflammatory cytokines secretion in microglial cells in vitro. Phosphoproteomic signals suggest that CN‐105 reduces proinflammatory pathways and lower oxidative stress.

Interpretation

CN‐105 improves functional and histological outcomes in a murine model of ischemic stroke via modulation of neuroinflammatory pathways. Recent clinical trial of this compound has demonstrated favorable pharmacokinetic and safety profile, suggesting that CN‐105 represents an attractive candidate for clinical translation.

Phase 1 Randomized, Double-Blind, Placebo-Controlled Study to Determine the Safety, Tolerability, and Pharmacokinetics of a Single Escalating Dose and Repeated Doses of CN-105 in Healthy Adult Subjects

Spontaneous intracranial hemorrhage (ICH) remains a devastating stroke subtype, affecting as many as 80,000 people annually in the United States and associated with extremely high mortality. In the absence of any pharmacological interventions demonstrated to improve outcome, care for patients with ICH remains largely supportive. Thus, despite advances in the understanding of ICH and brain injury, there remains an unmet need for interventions that improve neurologic recovery and outcomes. Recent research suggesting inflammation and APOE genotype play a role in modifying neurologic outcome after brain injury has led to the development of an APOE-derived peptide agent (CN-105). Preclinical studies have demonstrated that CN-105 effectively downregulates the inflammatory response in acute brain injury, including ICH. Following Investigational New Drug (IND) enabling studies in murine models, this first-in-human single escalating dose and multiple dose placebo-controlled clinical trial was performed to define the safety and pharmacokinetics (PK) of CN-105. A total of 48 subjects (12 control, 36 active) were randomized in this study; all subjects completed the study. No significant safety issues were identified with both dosing regimens, and PK analysis revealed linearity without significant drug accumulation. The median half-life in the terminal elimination phase of CN-105 following a single or repeated dosing regimen did not change (approximately 3.6 hours). With the PK and preliminary safety of CN-105 established, the drug is now poised to begin first-in-disease phase 2 clinical trials in patients with ICH who urgently need new therapeutic options.

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.

Neuroprotective pentapeptide CN-105 improves functional and histological outcomes in a murine model of intracerebral hemorrhage

Presently, no pharmacological treatments have been demonstrated to improve long-term functional outcomes following intracerebral hemorrhage (ICH). Clinical evidence associates apolipoprotein E (apoE) genotype with ICH incidence and outcome. While apoE modifies neuroinflammatory responses through its adaptive role in glial downregulation, intact apoE holoprotein is too large to cross the blood-brain barrier (BBB). Therefore, we developed a 5-amino acid peptide – CN-105 – that mimics the polar face of the apoE helical domain involved in receptor interactions. In the current study, we investigated the therapeutic potential of CN-105 in a mouse model of ICH. Three doses of CN-105 (0.05 mg/kg) was administered by tail vein injection within 24 hours after ICH induction. Functional assessment showed durable improvement in vestibulomotor performance after CN-105 treatment, as quantified by increased Rotarod latencies on Days 1–5 post-ICH, and long-term improvement in neurocognitive performance, as quantified by reduced Morris water maze latencies on Days 29–32 post-ICH. Further, brain water content was significantly reduced, neuroinflammation was decreased and hippocampal CA3 neuronal survival was increased, although hemorrhage volume was not affected by CN-105. We concluded, therefore, that pentapeptide CN-105 improved short- and long-term neurobehavioral outcomes in a murine model of ICH, suggesting therapeutic potential for patients with acute ICH.

Apolipoprotein E-Mimetic COG1410 Reduces Acute Vasogenic Edema following Traumatic Brain Injury

The degree of post-traumatic brain edema and dysfunction of the blood-brain barrier (BBB) influences the neurofunctional outcome after a traumatic brain injury (TBI). Previous studies have demonstrated that the administration of apolipoprotein E-mimetic peptide COG1410 reduces the brain water content after subarachnoid hemorrhage, intra-cerebral hemorrhage, and focal brain ischemia. However, the effects of COG1410 on vasogenic edema following TBI are not known. The current study evaluated the effects of 1 mg/kg daily COG1410 versus saline administered intravenously after a controlled cortical impact (CCI) injury on BBB dysfunction and vasogenic edema at an acute stage in mice. The results demonstrated that treatment with COG1410 suppressed the activity of matrix metalloproteinase-9, reduced the disruption of the BBB and Evans Blue dye extravasation, reduced the TBI lesion volume and vasogenic edema, and decreased the functional deficits compared with mice treated with vehicle, at an acute stage after CCI. These findings suggest that COG1410 is a promising preclinical therapeutic agent for the treatment of traumatic brain injury.

A behavioral and histological comparison of fluid percussion injury and controlled cortical impact injury to the rat sensorimotor cortex

Our primary goal was to evaluate the behavioral and histological outcome of fluid percussion injury (FPI) and cortical contusion injury (CCI) to the sensorimotor cortex (SMC). The SMC has been used to evaluate neuroplasticity following CCI, but has not been extensively examined with FPI. In both the CCI and FPI models, a mechanical force of 4mm in diameter was applied over the SMC, allowing for a direct comparison to measure the relative rates of histology and recovery of function in these models. Gross behavioral deficits were found on the sensory task (tactile adhesive removal task) and multiple motor assessments (forelimb asymmetry task, forelimb placing task, and rotorod). These sensorimotor deficits occurred in the absence of cognitive deficits in the water maze. The CCI model creates focal damage with a localized injury wheras the FPI model creates a more diffuse injury causing widespread damage. Both behavioral and histological deficits ensued following both models of injury to the SMC. The neuroplastic changes and ease at which damage to this area can be measured behaviorally make this an excellent location to assess traumatic brain injury (TBI) treatments. No injury model can completely mimic the full spectrum of human TBI and any potential treatments should be validated across both focal and diffuse injury models. Both of these injury models to the SMC produce severe and enduring behavioral deficits, which are ideal for evaluating treatment options.

Neuroprotective peptides fused to arginine-rich cell penetrating peptides: Neuroprotective mechanism likely mediated by peptide endocytic properties

Several recent studies have demonstrated that TAT and other arginine-rich cell penetrating peptides (CPPs) have intrinsic neuroprotective properties in their own right. Examples, we have demonstrated that in addition to TAT, poly-arginine peptides (R8 to R18; containing 8-18 arginine residues) as well as some other arginine-rich peptides are neuroprotective in vitro (in neurons exposed to glutamic acid excitotoxicity and oxygen glucose deprivation) and in the case of R9 in vivo (after permanent middle cerebral artery occlusion in the rat). Based on several lines of evidence, we propose that this neuroprotection is related to the peptide's endocytosis-inducing properties, with peptide charge and arginine residues being critical factors. Specifically, we propose that during peptide endocytosis neuronal cell surface structures such as ion channels and transporters are internalised, thereby reducing calcium influx associated with excitotoxicity and other receptor-mediated neurodamaging signalling pathways. We also hypothesise that a peptide cargo can act synergistically with TAT and other arginine-rich CPPs due to potentiation of the CPPs endocytic traits rather than by the cargo-peptide acting directly on its supposedly intended intracellular target. In this review, we systematically consider a number of studies that have used CPPs to deliver neuroprotective peptides to the central nervous system (CNS) following stroke and other neurological disorders. Consequently, we critically review evidence that supports our hypothesis that neuroprotection is mediated by carrier peptide endocytosis. In conclusion, we believe that there are strong grounds to regard arginine-rich peptides as a new class of neuroprotective molecules for the treatment of a range of neurological disorders.

A Combination Therapy of Nicotinamide and Progesterone Improves Functional Recovery following Traumatic Brain Injury

Neuroprotection, recovery of function, and gene expression were evaluated in an animal model of traumatic brain injury (TBI) after a combination treatment of nicotinamide (NAM) and progesterone (Prog). Animals received a cortical contusion injury over the sensorimotor cortex, and were treated with either Vehicle, NAM, Prog, or a NAM/Prog combination for 72 h and compared with a craniotomy only (Sham) group. Animals were assessed in a battery of behavioral, sensory, and both fine and gross motor tasks, and given histological assessments at 24 h post-injury to determine lesion cavity size, degenerating neurons, and reactive astrocytes. Microarray-based transcriptional profiling was used to determine treatment-specific changes on gene expression. Our results confirm the beneficial effects of treatment with either NAM or Prog, demonstrating significant improvements in recovery of function and a reduction in lesion cavitation, degenerating neurons, and reactive astrocytes 24 h post-injury. The combination treatment of NAM and Prog led to a significant improvement in both neuroprotection at 24 h post-injury and recovery of function in sensorimotor related tasks when compared with individual treatments. The NAM/Prog-treated group was the only treatment group to show a significant reduction of cortical loss 24 h post-injury. The combination appears to affect inflammatory and immune processes, reducing expression of a significant number of genes in both pathways. Further preclinical trials using NAM and Prog as a combination treatment should be conducted to identify the window of opportunity, determine the optimal duration of treatment, and evaluate the combination in other pre-clinical models of TBI.

[Investigation of neuroprotective activity of apolipoprotein E peptide mimetic Cog1410 in transgenic lines of Drosophila melanogaster]

The neuroprotective activity of apolipoprotein E (apoE) peptide mimetic Cog1410, containing amino acid sequence of the receptor-binding domain apoE, has been investigated in transgenic lines of Drosophila melanogaster expressing human APP and beta-secretase. Expression of two transgenes caused neuropathological processes attributed to Alzheimer's disease: neurodegeneration, cognitive abnormality and amyloid deposits formation in brain. It was shown that Cog 1410 reduces neurodegeneration in brain of transgenic flies and improves cognitive functions (odor recognition). These data suggest that Cog1410 is a potential neuroprotector that can be used in AD treatment.

Inconsistencies and controversies surrounding the amyloid hypothesis of Alzheimer's disease

The amyloid hypothesis has driven drug development strategies for Alzheimer's disease for over 20 years. We review why accumulation of amyloid-beta (Aβ) oligomers is generally considered causal for synaptic loss and neurodegeneration in AD. We elaborate on and update arguments for and against the amyloid hypothesis with new data and interpretations, and consider why the amyloid hypothesis may be failing therapeutically. We note several unresolved issues in the field including the presence of Aβ deposition in cognitively normal individuals, the weak correlation between plaque load and cognition, questions regarding the biochemical nature, presence and role of Aβ oligomeric assemblies in vivo, the bias of pre-clinical AD models toward the amyloid hypothesis and the poorly explained pathological heterogeneity and comorbidities associated with AD. We also illustrate how extensive data cited in support of the amyloid hypothesis, including genetic links to disease, can be interpreted independently of a role for Aβ in AD. We conclude it is essential to expand our view of pathogenesis beyond Aβ and tau pathology and suggest several future directions for AD research, which we argue will be critical to understanding AD pathogenesis.

Comparison of the effects of erythropoietin and anakinra on functional recovery and gene expression in a traumatic brain injury model

The goal of this study was to compare the effects of two inflammatory modulators, erythropoietin (EPO) and anakinra, on functional recovery and brain gene expression following a cortical contusion impact (CCI) injury. Dosage regimens were designed to provide serum concentrations in the range obtained with clinically approved doses. Functional recovery was assessed using both motor and spatial learning tasks and neuropathological measurements conducted in the cortex and hippocampus. Microarray-based transcriptional profiling was used to determine the effect on gene expression at 24 h, 72 h, and 7 days post-CCI. Ingenuity Pathway Analysis was used to evaluate the effect on relevant functional categories. EPO and anakinra treatment resulted in significant changes in brain gene expression in the CCI model demonstrating acceptable brain penetration. At all three time points, EPO treatment resulted in significantly more differentially expressed genes than anakinra. For anakinra at 24 h and EPO at 24 h, 72 h, and 7 days, the genes in the top 3 functional categories were involved in cellular movement, inflammatory response and cell-to-cell signaling. For EPO, the majority of the genes in the top 10 canonical pathways identified were associated with inflammatory and immune signaling processes. This was true for anakinra only at 24 h post-traumatic brain injury (TBI). The immunomodulation effects of EPO and anakinra did not translate into positive effects on functional behavioral and lesion studies. Treatment with either EPO or anakinra failed to induce significant beneficial effects on recovery of function or produce any significant effects on the prevention of injury induced tissue loss at 30 days post-injury. In conclusion, treatment with EPO or anakinra resulted in significant effects on gene expression in the brain without affecting functional outcome. This suggests that targeting these inflammatory processes alone may not be sufficient for preventing secondary injuries after TBI.

Proteomic and functional annotation analysis of injured peripheral nerves reveals ApoE as a protein upregulated by injury that is modulated by metformin treatment

Background

Peripheral nerve injury (PNI) results in a fundamental reorganization of the translational machinery in the injured peripheral nerve such that protein synthesis is increased in a manner linked to enhanced mTOR and ERK activity. We have shown that metformin treatment, which activates adenosine monophosphate-activated protein kinase (AMPK), reverses tactile allodynia and enhanced translation following PNI. To gain a better understanding of how PNI changes the proteome of the sciatic nerve and ascertain how metformin treatment may cause further change, we conducted a range of unbiased proteomic studies followed by biochemical experiments to confirm key results.

Results

We used multidimensional protein identification technology (MUDPIT) on sciatic nerve samples taken from rats with sham surgery, spinal nerve ligation (SNL) surgery or SNL + 200 mg/kg metformin treatment. MUDPIT analysis on these complex samples yielded a wide variety of proteins that were sorted according to their peptide counts in SNL and SNL + metformin compared to sham. These proteins were then submitted to functional annotation analysis to identify potential functional networks altered by SNL and SNL + metformin treatment. Additionally, we used click-chemistry-based labeling and purification of nascently synthesized proteins followed by MUDPIT to further identify peptides that were synthesized within the injured nerve. With these methods, we identified apolipoprotein E (ApoE) as a protein profoundly increased by PNI and further increased by PNI and metformin. This result was confirmed by Western Blot of samples from SNL rats and spared nerve injury (SNI) mice. Furthermore, we show that 7-day treatment with metformin in naïve mice leads to an increase in ApoE expression in the sciatic nerve.

Conclusions

These proteomic findings support the hypothesis that PNI leads to a fundamental reorganization of gene expression within the injured nerve. Our data identify a key association of ApoE with PNI that is regulated by metformin treatment. We conclude from the known functions of ApoE in the nervous system that ApoE may be an intrinsic factor linked to nerve regeneration after PNI, an effect that is further enhanced by metformin treatment.

A comparison of the effects of nicotinamide and progesterone on functional recovery of cognitive behavior following cortical contusion injury in the rat

The primary goal of this study was to compare clinically relevant doses of progesterone and nicotinamide within the same injury model. Progesterone has been shown to reduce edema and inflammation and improve functional outcomes following brain injury. Nicotinamide has also been shown to be an effective neuroprotective agent in a variety of neurological injury models. In the current study, nicotinamide was administered beginning 4 h post-cortical contusion injury (CCI) with a loading dose (75 mg/kg, i.p.) combined with continuous infusion (12 mg/h/kg, s.c.) for 72 h post-injury. Progesterone was administered beginning 4 h post-CCI at a dose of 10 or 20 mg/kg, i.p. every 12 h for 72 h. This resulted in the following groups: Injured-nicotinamide treated, Injured-progesterone-10 treated, Injured-progesterone-20 treated, Injured-vehicle treated, and Sham. Functional recovery was assessed with two spatial memory tasks in the Morris water maze (MWM) the acquisition of a reference memory task and a reversal learning task. Neuropathological assessments were conducted in the cortex and hippocampus. It was found that both progesterone (10 mg/kg) and nicotinamide improved reference memory acquisition and reversal learning in the MWM compared with vehicle treatment. The lower dose of progesterone and nicotinamide also reduced tissue loss in the injured cortex and ipsilateral hippocampus compared with vehicle. The beneficial effects of progesterone appear to be dose dependent with the lower 10 mg/kg dose producing significant effects that were not observed at the higher dose. Direct comparison between nicotinamide and low dose progesterone appears to suggest that both are equally effective. The general findings of this study suggest that both nicotinamide and progesterone produce significant improvements in recovery of function following CCI.

ApolipoproteinE mimetic peptides improve outcome after focal ischemia

Growing clinical evidence implicates isoform-specific effects of apolipoprotein E (apoE) in reducing neuroinflammation and mediating adaptive responses following ischemic and traumatic brain injury. However, the intact apoE holoprotein does not cross the blood-brain barrier and thus has limited therapeutic potential. We have created a small peptide, COG1410 (acetyl-AS-Aib-LRKL-Aib-KRLL-amide), derived from the apoE receptor-binding region. COG1410 retains the anti-inflammatory and neuroprotective biological properties of the intact holoprotein and penetrates the blood-brain barrier. In the current study, we utilized a murine model of transient focal cerebral ischemia and reperfusion to demonstrate that intravenous (IV) administration of COG1410 reduces infarct volume and radiographic progression of infarct, and improves functional outcome as assessed by rotarod when delivered up to 4h after ischemia onset.

Tumor necrosis factor-induced cerebral insulin resistance in Alzheimer's disease links numerous treatment rationales

The evident limitations of the amyloid theory of the pathogenesis of Alzheimer's disease are increasingly putting alternatives in the spotlight. We argue here that a number of independently developing approaches to therapy-including specific and nonspecific anti-tumor necrosis factor (TNF) agents, apolipoprotein E mimetics, leptin, intranasal insulin, the glucagon-like peptide-1 mimetics and glycogen synthase kinase-3 (GSK-3) antagonists-are all part of an interlocking chain of events. All these approaches inform us that inflammation and thence cerebral insulin resistance constitute the pathway on which to focus for a successful clinical outcome in treating this disease. The key link in this chain presently absent is a recognition by Alzheimer's research community of the long-neglected history of TNF induction of insulin resistance. When this is incorporated into the bigger picture, it becomes evident that the interventions we discuss are not competing alternatives but equally valid approaches to correcting different parts of the same pathway to Alzheimer's disease. These treatments can be expected to be at least additive, and conceivably synergistic, in effect. Thus the inflammation, insulin resistance, GSK-3, and mitochondrial dysfunction hypotheses are not opposing ideas but stages of the same fundamental, overarching, pathway of Alzheimer's disease pathogenesis. The insight this provides into progenitor cells, including those involved in adult neurogenesis, is a key part of this approach. This pathway also has therapeutic implications for other circumstances in which brain TNF is pathologically increased, such as stroke, traumatic brain injury, and the infectious disease encephalopathies.

A discrimination task used as a novel method of testing decision-making behavior following traumatic brain injury

Traumatic brain injury (TBI) results in a multitude of deficits following injury. Some of the most pervasive in humans are the changes that affect frontally-mediated cognitive functioning, such as decision making. The assessment of decision-making behavior in rodents has been extensively tested in the field of the experimental analysis of behavior. However, due to the narrow therapeutic window following TBI, time-intensive operant paradigms are rarely incorporated into the battery of tests traditionally used, the majority of which assess motor and sensory functioning. The cognitive measures that are used are frequently limited to memory and do not account for changes in decision-making behavior. The purpose of the present study was to develop a simplified discrimination task that can assess deficits in decision-making behavior in rodents. For the task, rats were required to dig in cocoa-scented sand (versus unscented sand) for a reinforcer. Rats were given 12 sessions per day until a criterion level of 80% accuracy for 3 days straight was reached. Once the criterion was achieved, cortical contusion injuries were induced (frontal, parietal, or sham). Following a recovery period, the rats were re-tested on cocoa versus unscented sand. Upon reaching criterion, a reversal discrimination was evaluated in which the reinforcer was placed in unscented sand. Finally, a novel scent discrimination (basil versus coffee with basil reinforced), and a reversal (coffee) were evaluated. The results indicated that the Dig task is a simple experimental preparation that can be used to assess deficits in decision-making behavior following TBI.

A cannabinoid type 2 receptor agonist attenuates blood-brain barrier damage and neurodegeneration in a murine model of traumatic brain injury

After traumatic brain injury (TBI), inflammation participates in both the secondary injury cascades and the repair of the CNS, both of which are influenced by the endocannabinoid system. This study determined the effects of repeated treatment with a cannabinoid type 2 receptor (CB(2) R) agonist on blood-brain barrier integrity, neuronal degeneration, and behavioral outcome in mice with TBI. We also looked for the presence of a prolonged treatment effect on the macrophage/microglial response to injury. C57BL/6 mice underwent controlled cortical impact (CCI) and received repeated treatments with a CB(2) R agonist, 0-1966, or vehicle. After euthanasia at 6 hr or 1, 2, 3, or 7 days postinjury, brains were removed for histochemical analysis. Blood-brain barrier permeability changes were evaluated by using sodium fluorescein (NaF). Perilesional degenerating neurons, injury volumes, and macrophage/microglia cells were quantified by stereological methods. Rota-rod and open-field testing were performed to evaluate motor function and natural exploratory behavior in mice. 0-1966 Treatment resulted in a significant reduction in NaF uptake and number of degenerating neurons compared with the vehicle-treated group. 0-1966-Treated mice demonstrated improvement on rota-rod and open-field testing compared with vehicle-treated mice. These changes in CCI mice treated with 0-1966 were associated with a prolonged reduction in macrophage/microglia cell counts. In conclusion, repeated treatments with a CB(2) R agonist, 0-1966, result in attenuated blood-brain barrier disruption and neuronal degeneration. In addition, repeated treatment with 0-1966 shows prolonged treatment effects on behavior and the macrophage/microglia cell response over several days.

The apoE-mimetic peptide, COG1410, improves functional recovery in a murine model of intracerebral hemorrhage

BACKGROUND

Apolipoprotein E has previously been demonstrated to modulate acute brain injury responses, and administration of COG1410, an apoE-mimetic peptide derived from the receptor-binding region of apoE, improves outcome in preclinical models of acute neurological injury. In the current study, we sought to establish the optimal dose and timing of peptide administration associated with improved functional outcome in a murine model of intracerebral hemorrhage (ICH).

METHODS

Ten to twelve-week-old C57/BL6 male mice were injured by collagenase-induced ICH and randomly selected to receive either vehicle or one of four doses of COG1410 (0.5, 1, 2, or 4 mg/kg) via tail vein injection at 30 min after injury and then daily for 5 days. The injured mice were euthanized at various time points to assess inflammatory mediators, cerebral edema, and hematoma volume. Over the first 5 days following injury, vestibulomotor function was tested via Rotorod (RR) latency. After an optimal dose was demonstrated, a final cohort of animals was injured with ICH and randomly assigned to receive the first dose of COG1410 or vehicle at increasingly longer treatment initiation times after injury. The mice were then assessed for functional deficit via RR testing over the first 5 days following injury.

RESULTS

The mice receiving 2 mg/kg of COG1410 after injury demonstrated reduced functional deficit, decreased brain concentrations of inflammatory proteins, and less cerebral edema, although hematoma volume did not vary. The improved RR performance was maintained when peptide administration was delayed for up to 2 h after ICH.

CONCLUSIONS

COG1410 administered at a dose of 2 mg/kg within 2 h after injury improves functional recovery in a murine model of ICH.

Apolipoprotein E COG 133 mimetic peptide improves 5-fluorouracil-induced intestinal mucositis

Background

Intestinal mucositis is one of the major troublesome side effects of anticancer chemotherapy leading to poor patient compliance. In this study we addressed the role of the novel apolipoprotein E (ApoE) COG 133 mimetic peptide in 5-fluorouracil (5-FU)-challenged Swiss mice and IEC-6 cell monolayers. Experiments were also conducted in C57BL6J ApoE knock-out mice to assess the effects of apoE peptide treatment.

Methods

Experimental groups were as follows: unchallenged controls, 5-FU-challenged mice (450 mg/kg, i.p) with or without the ApoE peptide (0.3, 1, and 3 μM, given twice daily i.p. for 4 days). Mice were sacrificed 3 days after 5-FU challenge. Proximal small intestinal samples were harvested for molecular biology and histological processing. We conducted ELISA assays and RT-PCR to target IL-1β, TNF-α, IL-10, iNOS, and myeloperoxidase (MPO) to assess intestinal inflammation. Cell death and NF-κB assays were also conducted in apoE knock-out mice. In our in vitro models, IEC-6 cells were exposed to 1 mM of 5-FU in glutamine free media with or without the ApoE peptide (0.02, 0.2, 2, 5, 10, and 20 μM). We investigated IEC-6 cell proliferation and migration, 24 h after the 5-FU challenge. Additionally, apoptotic IEC-6 cells were measured by Tunel and flow cytometry. Equimolar doses of the ApoA-I (D4-F) peptide were also used in some experiments for comparative studies.

Results

Villus blunting and heavy inflammatory infiltrates were seen in the 5-FU-challenged group, findings that were partially ameliorated by the ApoE peptide. We found increased intestinal MPO and pro-inflammatory IL-1β and TNF-α levels, and TNF-α and iNOS transcripts, and reduction of IL-10 following 5-FU treatment, each of which were partially abrogated by the peptide. Improvements were also found in IEC-6 cell apoptosis and migration following ApoE and D-4F treatment.

Conclusion

Altogether, these findings suggest that the novel ApoE COG 133 mimetic peptide can reduce 5-FU-induced intestinal changes and potentially benefit mucositis.

Administration of COG1410 reduces axonal amyloid precursor protein immunoreactivity and microglial activation after controlled cortical impact in mice

Traumatic axonal injury (TAI) accounts for at least 35% of the morbidity and mortality in traumatic brain injury (TBI) patients without space-occupying lesions. It is also believed to be a key determinant of adverse outcomes such as cognitive dysfunction across the spectrum of TBI severity. Previous studies have shown that COG1410, a synthetic peptide derived from the apolipoprotein E (apoE) receptor binding region, has anti-inflammatory effects after experimental TBI, with improvements in cognitive recovery. However, the effects of COG1410 on axonal injury following TBI are not known. The current study evaluated the effects of 1 mg/kg daily COG1410 versus saline administered intravenously starting 30 min after controlled cortical impact (CCI) injury on pericontusional TAI in young, wild-type C57BL6/J male mice. We found that COG1410 did not affect the number of amyloid precursor protein (APP)-immunoreactive axonal varicosities in the pericontusional corpus callosum and external capsule at 24 h, but reduced APP-immunoreactive varicosities by 31% at 3 days (p=0.0023), and 36% at 7 days (p=0.0009). COG1410 significantly reduced the number of Iba1-positive cells with activated microglial morphology at all three time points by 21-30%. There was no effect of COG1410 on pericontusional white matter volume or silver staining at any time point. This indicates a possible effect of COG1410 on delayed but not immediate TAI. Future studies are needed to investigate the underlying mechanisms, therapeutic time window, and physiological implications of this effect.

Evidence that an APOE ε4 'double whammy' increases risk for Alzheimer's disease

Temporal lobe epilepsy (TLE) is associated with some of the same neuropathological features as those reported for early stages of typical Alzheimer's disease (AD). The APOE ε4 allele is associated with a gene-dose-dependent increase in AD risk and in the severity of amyloid-β (Aβ) pathology. In a study published in the current BMC Medicine, Sue Griffin and colleagues studied markers of brain resilience in the amputated temporal lobes of TLE patients. They discovered compelling evidence that the APOE ε3 isoform in TLE patients is apparently more neuroprotective from Aβ toxicity than is the APOE ε4 isoform, as shown by the reduced levels of neuronal damage, glial activation, and expression of IL-1α in the APOE ε3/ε3 brains. This result points to a new property of APOE isoforms: not only are APOE ε4 alleles associated with increased brain amyloid plaque burden, but these alleles are also apparently inferior to APOE ε3 alleles in conveying resistance to Aβ neurotoxicity. This 'double whammy' result opens up a new direction for studies aimed at elucidating the relevant neurobiological activities of APOE isoforms in the pathogenesis of AD.

The effects of a high-fat sucrose diet on functional outcome following cortical contusion injury in the rat

Traumatic brain injury (TBI) is a major public health issue affecting 1.7 million Americans each year, of which approximately 50,000 are fatal. High-fat sucrose (HFS) diets are another public health issue which can lead to obesity, hypertension, and many other debilitating disorders. These two disorders combined can lead to more complicated issues. It has recently been shown that HFS diets can reduce levels of brain-derived neurotrophic factor (BDNF) leading to reductions in neuronal and behavioral plasticity. This reduction in BDNF is suspected of increasing the susceptibility of the brain to injury. To test the effects of a HFS diet on recovery of function post-TBI, male Sprague-Dawley rats were used in this study. Eight weeks prior to TBI, rats were placed on a special HFS diet (n=14) or a standard rodent diet (n=14). Following this eight-week period, rats were prepared with bilateral frontal cortical contusion injuries (CCI) or sham procedures. Beginning two days post-TBI, animals were tested on a battery of behavioral tests to assess somatosensory dysfunction and spatial memory in the Morris water maze, with a reference memory and a working memory task. Following testing, animals were sacrificed and their brains processed for lesion analysis. The HFS diet worsened performance on the bilateral tactile adhesive removal test in sham animals. Injured animals on the Standard diet had a greater improvement in somatosensory performance in the adhesive removal test and had better performance on the working memory task compared to animals on the HFS diet. The HFS diet also resulted in significantly greater loss of cortical tissue post-CCI than in the Standard diet group. This study may aid in determining how nutritional characteristics or habits interact with damage to the brain.

Early and sustained increase in the expression of hippocampal IGF-1, but not EPO, in a developmental rodent model of traumatic brain injury

Pediatric traumatic brain injury (pTBI) is the leading cause of traumatic death and disability in children in the United States. Impaired learning and memory in these young survivors imposes a heavy toll on society. In adult TBI (aTBI) models, cognitive outcome improved after administration of erythropoietin (EPO) or insulin-like growth factor-1 (IGF-1). Little is known about the production of these agents in the hippocampus, a brain region critical for learning and memory, after pTBI. Our objective was to describe hippocampal expression of EPO and IGF-1, together with their receptors (EPOR and IGF-1R, respectively), over time after pTBI in 17-day-old rats. We used the controlled cortical impact (CCI) model and measured hippocampal mRNA levels of EPO, IGF-1, EPOR, IGF-1R, and markers of caspase-dependent apoptosis (bcl2, bax, and p53) at post-injury days (PID) 1, 2, 3, 7, and 14. CCI rats performed poorly on Morris water maze testing of spatial working memory, a hippocampally-based cognitive function. Apoptotic markers were present early and persisted for the duration of the study. EPO in our pTBI model increased much later (PID7) than in aTBI models (12 h), while EPOR and IGF-1 increased at PID1 and PID2, respectively, similar to data from aTBI models. Our data indicate that EPO expression showed a delayed upregulation post-pTBI, while EPOR increased early. We speculate that administration of EPO in the first 1-2 days after pTBI would increase hippocampal neuronal survival and function.

Preclinical efficacy testing in middle-aged rats: nicotinamide, a novel neuroprotectant, demonstrates diminished preclinical efficacy after controlled cortical impact

Age is a consistent predictor of poor outcome following traumatic brain injury (TBI). Although the elderly population has one of the highest rates of TBI-related hospitalization and death, few preclinical studies have attempted to model and treat TBI in the aged population. Recent studies have indicated that nicotinamide (NAM), a soluble B-group vitamin, improved functional recovery in experimental models of TBI in young animals. The purpose of the present study was to examine the preclinical efficacy of NAM in middle-aged rats. Groups of middle-aged (14-month-old) rats were assigned to NAM (500 mg/kg or 50 mg/kg) or saline alone (1 mL/kg) treatment conditions, and received unilateral cortical contusion injuries (CCI) and injections at 1 h and 24 h following injury. The animals were tested on a variety of tasks to assess vestibulomotor (tapered beam) and cognitive performance (reference and working memory in the Morris water maze), and were evaluated for lesion size, blood-brain barrier compromise, astrocytic activation, and edema formation. In summary, the preclinical efficacy of NAM as a treatment following CCI in middle-aged rats differs from that previously documented in younger rats; while treatment with 50 mg/kg NAM appeared to have no effect, the 500-mg/kg dose worsened performance in middle-aged animals. Histological indicators demonstrated more nuanced group differences, indicating that NAM may positively impact some of the cellular cascades following injury, but were not substantial enough to improve functional recovery. These findings emphasize the need to examine potential treatments for TBI utilizing non-standard populations, and may explain why so many treatments have failed in clinical trials.

COG1410, an apolipoprotein E-based peptide, improves cognitive performance and reduces cortical loss following moderate fluid percussion injury in the rat

COG1410, a small, novel ApoE-mimetic peptide derived from the receptor binding region of apolipoprotein E (ApoE), has been classified as anti-inflammatory in nature and improves motor, sensorimotor, and cognitive dysfunction following cortical contusion injury (CCI). In order to further examine COG1410's preclinical efficacy on cognitive recovery, the present study evaluated COG1410 following moderate fluid percussion injury (FPI). Animals were prepared with a moderate, unilateral FPI over the hippocampus. Following FPI, animals received a regimen of five doses of COG1410 or vehicle at 2 and 4h (1.0mg/kg, i.v.) followed by additional doses administered 24, 48, and 72 h (1.0mg/kg, i.p.). Prior to injury, animals were trained for 4 days (4 trials/day) in the Morris water maze (MWM) and then tested for retrograde amnesia on post-FPI day 11 and then on a working memory task on day 18. Testing for motor dysfunction on the tapered balanced beam began on day 2 post-FPI. Administration of this regimen of COG1410 significantly improved retention of memory in the retrograde amnesia test compared to vehicle post-FPI. However, COG1410 did not significantly improve acquisition of working memory in the MWM. Motor dysfunction on the tapered beam post-FPI was improved in the COG1410-treated group compared to vehicle treatment. Cortical lesion analysis revealed that the COG1410-treated animals demonstrated significantly less tissue loss compared to vehicle-treated animals. The results of this study suggest that COG1410 significantly limited the behavioral dysfunction and tissue loss associated with FPI and demonstrated continued preclinical efficacy for TBI.

Administration of S-nitrosoglutathione after traumatic brain injury protects the neurovascular unit and reduces secondary injury in a rat model of controlled cortical impact

Background

Traumatic brain injury (TBI) is a major cause of preventable death and serious morbidity in young adults. This complex pathological condition is characterized by significant blood brain barrier (BBB) leakage that stems from cerebral ischemia, inflammation, and redox imbalances in the traumatic penumbra of the injured brain. Once trauma has occurred, combating these exacerbations is the keystone of an effective TBI therapy. Following other brain injuries, nitric oxide modulators such as S-nitrosoglutathione (GSNO) maintain not only redox balance but also inhibit the mechanisms of secondary injury. Therefore, we tested whether GSNO shows efficacy in a rat model of experimental TBI.

Methods

TBI was induced by controlled cortical impact (CCI) in adult male rats. GSNO (50 μg/kg body weight) was administered at two hours after CCI. GSNO-treated injured animals (CCI+GSNO group) were compared with vehicle-treated injured animals (CCI+VEH group) in terms of tissue morphology, BBB leakage, edema, inflammation, cell death, and neurological deficit.

Results

Treatment of the TBI animals with GSNO reduced BBB disruption as evidenced by decreased Evan's blue extravasation across brain, infiltration/activation of macrophages (ED1 positive cells), and reduced expression of ICAM-1 and MMP-9. The GSNO treatment also restored CCI-mediated reduced expression of BBB integrity proteins ZO-1 and occludin. GSNO-mediated improvements in tissue histology shown by reduction of lesion size and decreased loss of both myelin (measured by LFB staining) and neurons (assayed by TUNEL) further support the efficacy of GSNO therapy. GSNO-mediated reduced expression of iNOS in macrophages as well as decreased neuronal cell death may be responsible for the histological improvement and reduced exacerbations. In addition to these biochemical and histological improvements, GSNO-treated injured animals recovered neurobehavioral functions as evaluated by the rotarod task and neurological score measurements.

Conclusion

GSNO is a promising candidate to be evaluated in humans after brain trauma because it not only protects the traumatic penumbra from secondary injury and improves overall tissue structure but also maintains the integrity of BBB and reduces neurologic deficits following CCI in a rat model of experimental TBI.