MW151 Inhibited IL-1β Levels after Traumatic Brain Injury with No Effect on Microglia Physiological Responses

Therapeutic treatment with the anti-inflammatory drug candidate MW151 may partially reduce memory impairment and normalizes hippocampal metabolic markers in a mouse model of comorbid amyloid and vascular pathology

Alzheimer’s disease (AD) is the leading cause of dementia in the elderly, but therapeutic options are lacking. Despite long being able to effectively treat the ill-effects of pathology present in various rodent models of AD, translation of these strategies to the clinic has so far been disappointing. One potential contributor to this situation is the fact that the vast majority of AD patients have other dementia-contributing comorbid pathologies, the most common of which are vascular in nature. This situation is modeled relatively infrequently in basic AD research, and almost never in preclinical studies. As part of our efforts to develop small molecule, anti-inflammatory therapeutics for neurological injury and disease, we have recently been exploring potentially promising treatments in preclinical multi-morbidity contexts. In the present study, we generated a mouse model of mixed amyloid and hyperhomocysteinemia (HHcy) pathology in which to test the efficacy of one of our anti-inflammatory compounds, MW151. HHcy can cause cerebrovascular damage and is an independent risk factor for both AD dementia and vascular contributions to cognitive impairment and dementia. We found that MW151 was able to partially rescue hippocampal-dependent spatial memory and learning deficits in this comorbidity context, and further, that the benefit is associated with a normalization of hippocampal metabolites detectable via magnetic resonance spectroscopy. These findings provide evidence that MW151 in particular, and potentially anti-inflammatory treatment more generally, may be beneficial in AD patients with comorbid vascular pathology.

Intranasal delivery of exosomes from human adipose derived stem cells at forty-eight hours post injury reduces motor and cognitive impairments following traumatic brain injury

The neuroprotective role of human adipose-derived stems cells (hASCs) has raised great interest in regenerative medicine due to their ability to modulate their surrounding environment. Our group has demonstrated that exosomes derived from hASC (hASCexo) are a cell-free regenerative approach to long term recovery following traumatic brain injury (TBI). Previously, we demonstrated the efficacy of exosome treatment with intravenous delivery at 3 h post TBI in rats. Here, we show efficacy of exosomes through intranasal delivery at 48 h post TBI in mice lengthening the therapeutic window of treatment and therefore increasing possible translation to clinical studies. Our findings demonstrate significant recovery of motor impairment assessed by an elevated body swing test in mice treated with exosomes containing MALAT1 compared to both TBI mice without exosomes and exosomes depleted of MALAT1. Significant cognitive improvement was seen in the reversal trial of 8 arm radial arm water maze in mice treated with exosomes containing MALAT1. Furthermore, cortical damage was significantly reduced in mice treated with exosomes containing MALAT1 as well as decreased MHCII+ staining of microglial cells. Mice without exosomes or treated with exosomes depleted of MALAT1 did not show similar recovery. Results demonstrate both inflammation related genes and NRTK3 (TrkC) are target genes modulated by hASC exosomes and further that MALAT1 in hASC exosomes regulates expression of full length TrkC thereby activating the MAPK pathway and promoting recovery. Exosomes are a promising therapeutic approach following TBI with a therapeutic window of at least 48 h and contain long noncoding RNA's, specifically MALAT1 that play a vital role in the mechanism of action.

Does intermittent fasting associated with aerobic training influence parameters related to the gut-brain axis of Wistar rats?

BACKGROUND

Intermittent fasting (IF) and aerobic training have demonstrated beneficial effects on intestinal microbiota composition, but little is known about benefits to the brain through the gut-brain axis. The present study aimed to evaluate gut-brain axis parameters in Wistar rats submitted to IF associated or not with aerobic training.

METHODS

Male rats were evaluated for training performance and then randomized into 4 groups of ten: sedentary control (SC), trained control (TC), sedentary intermittent fasting (SIF), and trained intermittent fasting (TIF), and evaluated during four weeks.

RESULTS

The adiposity index was similar among the TC (2.15±0.43%), SIF (1.98±0.69%) and TIF (1.86±0.51%) groups, and differed from SC (2.98±0.80%). TIF had lower counts of lactic acid bacteria, while SIF had higher counts of Bifidobacterium and Enterococcus. TIF had the highest amount of formic acid in faeces (44.44±2.40 μmol/g) and lowest amount of succinic acid in the gut (0.38±0.00 μmol/g), while SIF had the highest propionic acid amount in the faeces (802.80±00.33 μmol/g) and the lowest amount of lactic acid in the gut (0.85±0.00 μmol/g). TIF demonstrated a tendency towards an anxiolytic effect and SIF showed potential antidepressant effect. IF caused different brain and intestinal injuries. TIF rats presented a diffuse and intense marking of IL-1β in the hippocampus.

CONCLUSION

IF and aerobic exercise, associated or not, can modulate parameters related to the gut-brain axis of Wistar rats, and some benefits may be related to the amounts of organic acids.

Neuroimmunological therapies for treating spinal cord injury: Evidence and future perspectives

Spinal cord injury (SCI) has a complex pathophysiology. Following the initial physical trauma to the spinal cord, which may cause vascular disruption, hemorrhage, mechanical injury to neural structures and necrosis, a series of biomolecular cascades is triggered to evoke secondary injury. Neuroinflammation plays a major role in the secondary injury after traumatic SCI. To date, the administration of systemic immunosuppressive medications, in particular methylprednisolone sodium succinate, has been the primary pharmacological treatment. This medication is given as a complement to surgical decompression of the spinal cord and maintenance of spinal cord perfusion through hemodynamic augmentation. However, the impact of neuroinflammation is complex with harmful and beneficial effects. The use of systemic immunosuppressants is further complicated by the natural onset of post-injury immunosuppression, which many patients with SCI develop. It has been hypothesized that immunomodulation to attenuate detrimental aspects of neuroinflammation after SCI, while avoiding systemic immunosuppression, may be a superior approach. To accomplish this, a detailed understanding of neuroinflammation and the systemic immune responses after SCI is required. Our review will strive to achieve this goal by first giving an overview of SCI from a clinical and basic science context. The role that neuroinflammation plays in the pathophysiology of SCI will be discussed. Next, the positive and negative attributes of the innate and adaptive immune systems in neuroinflammation after SCI will be described. With this background established, the currently existing immunosuppressive and immunomodulatory therapies for treating SCI will be explored. We will conclude with a summary of topics that can be explored by neuroimmunology research. These concepts will be complemented by points to be considered by neuroscientists developing therapies for SCI and other injuries to the central nervous system.

Neuroinflammation and progressive myoclonus epilepsies: from basic science to therapeutic opportunities

Progressive myoclonus epilepsies (PMEs) are a group of genetic neurological disorders characterised by the occurrence of epileptic seizures, myoclonus and progressive neurological deterioration including cerebellar involvement and dementia. The primary cause of PMEs is variable and alterations in the corresponding mutated genes determine the progression and severity of the disease. In most cases, they lead to the death of the patient after a period of prolonged disability. PMEs also share poor information on the pathophysiological bases and the lack of a specific treatment. Recent reports suggest that neuroinflammation is a common trait under all these conditions. Here, we review similarities and differences in neuroinflammatory response in several PMEs and discuss the window of opportunity of using anti-inflammatory drugs in the treatment of several of these conditions.

Comparison between midline and lateral fluid percussion injury in mice reveals prolonged but divergent cortical neuroinflammation

Animal models are critical for determining the mechanisms mediating traumatic brain injury-induced (TBI) neuropathology. Fluid percussion injury (FPI) is a widely used model of brain injury typically applied either midline or parasagittally (lateral). Midline FPI induces a diffuse TBI, while lateral FPI induces both focal cortical injury (ipsilateral hemisphere) and diffuse injury (contralateral hemisphere). Nonetheless, discrete differences in neuroinflammation and neuropathology between these two versions of FPI remain unclear. The purpose of this study was to compare acute (4-72 h) and subacute (7 days) neuroinflammatory responses between midline and lateral FPI. Midline FPI resulted in longer righting reflex times than lateral FPI. At acute time points, the inflammatory responses to the two different injuries were similar. For instance, there was evidence of monocytes and cytokine mRNA expression in the brain with both injuries acutely. Midline FPI had the highest proportion of brain monocytes and highest IL-1β/TNFα mRNA expression 24 h later. NanoString nCounter analysis 7 days post-injury revealed robust and prolonged expression of inflammatory-related genes in the cortex after midline FPI compared to lateral FPI; however, Iba-1 cortical immunoreactivity was increased with lateral FPI. Thus, midline and lateral FPI caused similar cortical neuroinflammatory responses acutely and mRNA expression of inflammatory genes was detectable in the brain 7 days later. The primary divergence was that inflammatory gene expression was greater and more diverse subacutely after midline FPI. These results provide novel insight to variations between midline and lateral FPI, which may recapitulate unique temporal pathogenesis.

Microglial process convergence on axonal segments in health and disease

Microglia dynamically interact with neurons influencing the development, structure, and function of neuronal networks. Recent studies suggest microglia may also influence neuronal activity by physically interacting with axonal domains responsible for action potential initiation and propagation. However, the nature of these microglial process interactions is not well understood. Microglial-axonal contacts are present early in development and persist through adulthood, implicating microglial interactions in the regulation of axonal integrity in both the developing and mature central nervous system. Moreover, changes in microglial-axonal contact have been described in disease states such as multiple sclerosis (MS) and traumatic brain injury (TBI). Depending on the disease state, there are increased associations with specific axonal segments. In MS, there is enhanced contact with the axon initial segment and node of Ranvier, while, in TBI, microglia alter interactions with axons at the site of injury, as well as at the axon initial segment. In this article, we review the interactions of microglial processes with axonal segments, analyzing their associations with various axonal domains and how these interactions may differ between MS and TBI. Furthermore, we discuss potential functional consequences and molecular mechanisms of these interactions and how these may differ among various types of microglial-axonal interactions.

A dual inhibitor of the proteasome catalytic subunits LMP2 and Y attenuates disease progression in mouse models of Alzheimer's disease

The immunoproteasome (iP) is a variant of the constitutive proteasome (cP) that is abundantly expressed in immune cells which can also be induced in somatic cells by cytokines such as TNF-α or IFN-γ. Accumulating evidence support that the iP is closely linked to multiple facets of inflammatory response, eventually leading to the development of several iP inhibitors as potential therapeutic agents for autoimmune diseases. Recent studies also found that the iP is upregulated in reactive glial cells surrounding amyloid β (Aβ) deposits in brains of Alzheimer’s disease (AD) patients, but the role it plays in the pathogenesis of AD remains unclear. In this study, we investigated the effects of several proteasome inhibitors on cognitive function in AD mouse models and found that YU102, a dual inhibitor of the iP catalytic subunit LMP2 and the cP catalytic subunit Y, ameliorates cognitive impairments in AD mouse models without affecting Aβ deposition. The data obtained from our investigation revealed that YU102 suppresses the secretion of inflammatory cytokines from microglial cells. Overall, this study indicates that there may exist a potential link between LMP2/Y and microglia-mediated neuroinflammation and that inhibition of these subunits may offer a new therapeutic strategy for AD.

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

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

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

BACKGROUND

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

OBJECTIVE/HYPOTHESIS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Neutralization of Interleukin-1β following Diffuse Traumatic Brain Injury in the Mouse Attenuates the Loss of Mature Oligodendrocytes

Traumatic brain injury (TBI) commonly results in injury to the components of the white matter tracts, causing post-injury cognitive deficits. The myelin-producing oligodendrocytes (OLs) are vulnerable to TBI, although may potentially be replaced by proliferating oligodendrocyte progenitor cells (OPCs). The cytokine interleukin-1β (IL-1β) is a key mediator of the complex inflammatory response, and when neutralized in experimental TBI, behavioral outcome was improved. To evaluate the role of IL-1β on oligodendrocyte cell death and OPC proliferation, 116 adult male mice subjected to sham injury or the central fluid percussion injury (cFPI) model of traumatic axonal injury, were analyzed at two, seven, and 14 days post-injury. At 30 min post-injury, mice were randomly administered an IL-1β neutralizing or a control antibody. OPC proliferation (5-ethynyl 2'- deoxyuridine (EdU)/Olig2 co-labeling) and mature oligodendrocyte cell loss was evaluated in injured white matter tracts. Microglia/macrophages immunohistochemistry and ramification using Sholl analysis were also evaluated. Neutralizing IL-1β resulted in attenuated cell death, indicated by cleaved caspase-3 expression, and attenuated loss of mature OLs from two to seven days post-injury in brain-injured animals. IL-1β neutralization also attenuated the early, two day post-injury increase of microglia/macrophage immunoreactivity and altered their ramification. The proliferation of OPCs in brain-injured animals was not altered, however. Our data suggest that IL-1β is involved in the TBI-induced loss of OLs and early microglia/macrophage activation, although not the OPC proliferation. Attenuated oligodendrocyte cell loss may contribute to the improved behavioral outcome observed by IL-1β neutralization in this mouse model of diffuse TBI.

Small Molecules: Therapeutic Application in Neuropsychiatric and Neurodegenerative Disorders

In recent years, an increasing number of studies have been published, focusing on the potential therapeutic use of small catalytic agents with strong biological properties. So far, most of these works have only regarded specific clinical fields, such as oncology, infectivology and general pathology, in particular with respect to the treatment of significant inflammatory processes. However, interesting data on possible therapeutic applications of small molecules for the treatment of neuropsychiatric and neurodegenerative illnesses are emerging, especially with respect to the possibility to modulate the cellular redox state. Indeed, a crucial role of redox dysregulation in the pathogenesis of these disorders has been widely demonstrated by both pre-clinical and clinical studies, being the reduction of the total amount of free radicals a promising novel therapeutic approach for these diseases. In this review, we focused our interest on studies published during the last ten years reporting therapeutic potential of small molecules for the treatment of neuropsychiatric and neurodegenerative disorders, also based on the biological efficiency of these compounds in detecting intracellular disturbances induced by increased production of reactive oxygen species.

Retention of normal glia function by an isoform-selective protein kinase inhibitor drug candidate that modulates cytokine production and cognitive outcomes

BACKGROUND

Brain p38α mitogen-activated protein kinase (MAPK), a potential therapeutic target for cognitive dysfunction based on the neuroinflammation-synaptic dysfunction cycle of pathophysiology progression, offers an innovative pharmacological strategy via inhibiting the same activated target in both glia and neurons, thereby enhancing the possibility for efficacy. The highly selective, brain-penetrant p38αMAPK inhibitor MW150 attenuates cognitive dysfunction in two distinct Alzheimer's disease (AD)-relevant models and avoids the problems encountered with previous mixed-kinase inhibitor drug candidates. Therefore, it is essential that the glial effects of this CNS-active kinase inhibitor be addressed in order to anticipate future use in clinical investigations.

METHODS

We explored the effects of MW150 on glial biology in the AD-relevant APP/PS1 knock-in (KI) mouse model where we previously showed efficacy in suppression of hippocampal-dependent associative and spatial memory deficits. MW150 (2.5 mg/kg/day) was administered daily to 11-12-month-old KI mice for 14 days, and levels of proinflammatory cytokines IL-1β, TNFα, and IL-6 measured in homogenates of mouse cortex using ELISA. Glial markers IBA1, CD45, CD68, and GFAP were assessed by immunohistochemistry. Microglia and amyloid plaques were quantified by immunofluorescence staining followed by confocal imaging. Levels of soluble and insoluble of Aβ40 and Aβ42 were measured by ELISA. The studies of in vivo pharmacodynamic effects on markers of neuroinflammation were complemented by mechanistic studies in the murine microglia BV2 cell line, using live cell imaging techniques to monitor proliferation, migration, and phagocytosis activities.

RESULTS

Intervention with MW150 in KI mice during the established therapeutic time window attenuated the increased levels of IL-1β and TNFα but not IL-6. MW150 treatment also increased the IBA1⁺ microglia within a 15 μm radius of the amyloid plaques, without significantly affecting overall microglia or plaque volume. Levels of IBA1, CD45, CD68, GFAP, and Aβ40 and Aβ42 were not affected by MW150 treatment. MW150 did not significantly alter microglial migration, proliferation, or phagocytosis in BV2 cells.

CONCLUSIONS

Our results demonstrate that MW150 at an efficacious dose can selectively modulate neuroinflammatory responses associated with pathology progression without pan-suppression of normal physiological functions of microglia.

Relationship of Circulating CXCR4+ EPC with Prognosis of Mild Traumatic Brain Injury Patients

To investigate the changes of circulating endothelial progenitor cells (EPCs) and stromal cell-derived factor-1α (SDF-1α)/CXCR4 expression in patients with mild traumatic brain injury (TBI) and the correlation between EPC level and the prognosis of mild TBI. 72 TBI patients (57 mild TBI, 15 moderate TBI patients) and 25 healthy subjects (control) were included. The number of circulating EPCs, CD34⁺, and CD133⁺ cells and the percentage of CXCR4⁺ cells in each cell population at 1,4,7,14,21 days after TBI were counted by flow cytometer. SDF-1α levels in serum were detected by ELISA assay. The patients were divided into poor and good prognosis groups based on Extended Glasgow Outcome Scale and Activity of Daily Living Scale at 3 months after TBI. Correlation analysis between each detected index and prognosis of mild TBI was performed. Moderate TBI patients have higher levels of SDF-1α and CXCR4 expression than mild TBI patients (P < 0.05). The percentage of CXCR4⁺ EPCs at day 7 post-TBI was significantly higher in mild TBI patients with poor prognosis than the ones with good prognosis (P < 0.05). HAMA and HAMD scores in mild TBI patients were significantly lower than moderate TBI patients (P < 0.05) in early term. The percentage of CXCR4⁺ EPCs at day 7 after TBI was significantly correlated with the prognosis outcome at 3 months. The mobilization of circulating EPCs can be induced in mild TBI. The expression of CXCR4⁺ in EPCs at 7 days after TBI reflects the short-term prognosis of brain injury, and could be a potential biological marker for prognosis prediction of mild TBI.