Mouse Model Of Traumatic Brain Injury Research Articles

The Ang-(1-7)/MasR axis ameliorates neuroinflammation in hypothermic traumatic brain injury in mice by modulating phenotypic transformation of microglia.

The Ang-(1-7)/MasR axis is critically involved in treating several diseases; For example, Ang-(1-7) improves inflammatory response and neurological function after traumatic brain injury and inhibits post-inflammatory hypothermia. However, its function in traumatic brain injury (TBI) combined with seawater immersion hypothermia remains unclear. Here, we used a mice model of hypothermic TBI and a BV2 cell model of hypothermic inflammation to investigate whether the Ang-(1-7)/MasR axis is involved in ameliorating hypothermic TBI. Quantitative reverse transcription PCR, western blotting assay, and immunofluorescence assay were performed to confirm microglia polarization and cytokine regulation. Hematoxylin-eosin staining, Nissl staining, and immunohistochemical assay were conducted to assess the extent of hypothermic TBI-induced damage and the ameliorative effect of Ang-(1-7) in mice. An open field experiment and neurological function scoring with two approaches were used to assess the degree of recovery and prognosis in mice. After hypothermic TBI establishment in BV2 cells, the Ang-(1-7)/MasR axis induced phenotypic transformation of microglia from M1 to M2, inhibited IL-6 and IL-1β release, and upregulated IL-4 and IL-10 levels. After hypothermic TBI development in mice, intraperitoneally administered Ang-(1-7) attenuated histological damage and promoted neurological recovery. These findings suggest that hypothermia exacerbates TBI-induced damage and that the Ang-(1-7)/MasR axis can ameliorate hypothermic TBI and directly affect prognosis.

Pharmacological inhibition of STING reduces neuroinflammation-mediated damage post-traumatic brain injury.

Traumatic brain injury (TBI) remains a major public health concern worldwide with unmet effective treatment. Stimulator of interferon genes (STING) and its downstream type-I interferon (IFN) signalling are now appreciated to be involved in TBI pathogenesis. Compelling evidence have shown that STING and type-I IFNs are key in mediating the detrimental neuroinflammatory response after TBI. Therefore, pharmacological inhibition of STING presents a viable therapeutic opportunity in combating the detrimental neuroinflammatory response after TBI. This study investigated the neuroprotective effects of the small-molecule STING inhibitor n-(4-iodophenyl)-5-nitrofuran-2-carboxamide (C-176) in the controlled cortical impact mouse model of TBI in 10- to 12-week-old male mice. Thirty minutes post-controlled cortical impact surgery, a single 750-nmol dose of C-176 or saline (vehicle) was administered intravenously. Analysis was conducted 2h and 24 h post-TBI. Mice administered C-176 had significantly smaller cortical lesion area when compared to vehicle-treated mice 24 h post-TBI. Quantitative temporal gait analysis conducted using DigiGait™ showed C-176 administration attenuated TBI-induced impairments in gait symmetry, stride frequency and forelimb stance width. C-176-treated mice displayed a significant reduction in striatal gene expression of pro-inflammatory cytokines Tnf-α, Il-1β and Cxcl10 compared to their vehicle-treated counterparts 2h post-TBI. This study demonstrates the neuroprotective activity of C-176 in ameliorating acute neuroinflammation and preventing white matter neurodegeneration post-TBI. This study highlights the therapeutic potential of small-molecule inhibitors targeting STING for the treatment of trauma-induced inflammation and neuroprotective potential.

PH-sensitive cationic nanoparticles for endosomal cell-free DNA scavenging against acute inflammation

Cell-free DNA (cfDNA) released from dead cells could be a player in some autoimmune disorders by activating Toll-like receptor 9 (TLR9) and inducing proinflammatory cytokines. Cationic nanoparticles (cNPs) address cfDNA clearance, yet challenges persist, including toxicity, low specificity and ineffectiveness against endocytosed cfDNA. This study introduced pH-sensitive cNPs, reducing off-target effects and binding cfDNA at inflammatory sites. This unique approach inhibits the TLR9 pathway, offering a novel strategy for inflammation modulation. Synthesized cNPs, with distinct cationic moieties, exhibit varied pKa values, enhancing cfDNA binding. Comprehensive studies elucidate the mechanism, demonstrating minimal extracellular binding, enhanced endosomal DNA binding, and optimal tumor necrosis factor-α suppression. In a traumatic brain injury mice model, pH-sensitive cNPs effectively suppress inflammatory cytokines, highlighting their potential in acute inflammation regulation.

Sex-specific and cell-specific regulation of ER stress and neuroinflammation after traumatic brain injury in juvenile mice

Endoplasmic reticulum (ER) stress and neuroinflammation play an important role in secondary brain damage after traumatic brain injury (TBI). Due to the complex brain cytoarchitecture, multiple cell types are affected by TBI. However, cell type-specific and sex-specific responses to ER stress and neuroinflammation remain unclear. Here we investigated differential regulation of ER stress and neuroinflammatory pathways in neurons and microglia during the acute phase post-injury in a mouse model of impact acceleration TBI in both males and females. We found that TBI resulted in significant weight loss only in males, and sensorimotor impairment and depressive-like behaviors in both males and females at the acute phase post-injury. By concurrently isolating neurons and microglia from the same brain sample of the same animal, we were able to evaluate the simultaneous responses in neurons and microglia towards ER stress and neuroinflammation in both males and females. We discovered that the ER stress and anti-inflammatory responses were significantly stronger in microglia, especially in female microglia, compared with the male and female neurons. Whereas the degree of phosphorylated-tau (pTau) accumulation was significantly higher in neurons, compared with the microglia. In conclusion, TBI resulted in behavioral deficits and cell type-specific and sex-specific responses to ER stress and neuroinflammation, and abnormal protein accumulation at the acute phase after TBI in immature mice.

Therapeutic efficacy of cinnamein, a component of balsam of Tolu/Peru, in controlled cortical impact mouse model of TBI

Traumatic brain injury (TBI) remains a major health concern which causes long-term neurological disability particularly in war veterans, athletes and young adults. In spite of intense clinical and research investigations, there is no effective therapy to cease the pathogenesis of the disease. It is believed that axonal injury during TBI is potentiated by neuroinflammation and demyelination and/or failure to remyelination. This study highlights the use of naturally available cinnamein, also chemically known as benzyl cinnamate, in inhibiting neuroinflammation, promoting remyelination and combating the disease process of controlled cortical impact (CCI)-induced TBI in mice. Oral delivery of cinnamein through gavage brought down the activation of microglia and astrocytes to decrease the expression of inducible nitric oxide synthase (iNOS), glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule 1 (Iba1) in hippocampus and cortex of TBI mice. Cinnamein treatment also stimulated remyelination in TBI mice as revealed by PLP and A2B5 double-labeling, luxol fast blue (LFB) staining and axonal double-labeling for neurofilament and MBP. Furthermore, oral cinnamein reduced the size of lesion cavity in the brain, improved locomotor functions and restored memory and learning in TBI mice. These results suggest a new neuroprotective property of cinnamein that may be valuable in the treatment of TBI.

Pre-clinical evaluation of 99mTc-labeled chalcone derivative for amyloid-β imaging post-head trauma.

Aβ42 plaque formation is one of the preliminary pathologic events that occur post traumatic brain injury (TBI) which is also among the most noteworthy hallmarks of AD. Their pre symptomatic detection is therefore vital for better disease management. Chalcone-picolinic acid chelator derivative, 6-({[(6-carboxypyridin-2-yl)methyl](2-{4-[(2E)-3-[4-(dimethyl amino)phenyl]prop-2-enoyl]phenoxy}ethyl)amino}methyl)pyridine-2-carboxylic acid, Py-chal was synthesized to selectively identify amyloid plaques formed post head trauma using SPECT imaging by stable complexation to 99mTc with > 97% efficiency without compromising amyloid specificity. The binding potential of the Py-chal ligand to amyloid plaques remained high as confirmed by in vitro binding assay and photophysical spectra. Further, the Py-chal complex stained amyloid aggregates in the brain sections of rmTBI mice model. In vivo scintigraphy in TBI mice model displayed high uptake followed by high retention while the healthy rabbits displayed higher brain uptake followed by a rapid washout attributed to absence of amyloid plaques. Higher uptake in brain of TBI model was also confirmed by ex vivo biodistribution analysis wherein brain uptake of 3.38 ± 0.2% ID/g at 2min p.i. was observed for TBI mice model. This was followed by prolonged retention and more than twofold higher activity as compared to sham mice brain. This preliminary data suggests the specificity of the radiotracer for amyloid detection post head trauma and applicability of 99mTc labeled Py-chal complex for TBI-induced β-amyloid SPECT imaging.

GSK’872 Improves Prognosis of Traumatic Brain Injury by Switching Receptor-Interacting Serine/Threonine-Protein Kinase 3-dependent Necroptosis to Cysteinyl Aspartate Specific Proteinase-8-Dependent Apoptosis

Traumatic brain injury (TBI) is an important health concern in the society. Previous studies have suggested that necroptosis occurs following TBI. However, the underlying mechanisms and roles of necroptosis are not well understood. In this study, we aimed to assess the role of receptor-interacting serine/threonine-protein kinase 3 (RIP3)-mediated necroptosis after TBI both in vitro and in vivo. We established a cell-stretching injury and mouse TBI model by applying a cell injury controller (CIC) and controlled cortical impactor (CCI) to evaluate the relationships among necroptosis, apotosis, inflammation, and TBI both in vitro and in vivo. The results revealed that necroptosis mediated by receptor-interacting serine/threonine-protein kinase 1 (RIP1), RIP3, and mixed lineage kinase domain-like protein (MLKL) was involved in secondary TBI. Additionally, protein kinase B (Akt), phosphorylated Akt (p-Akt), mammalian target of rapamycin (mTOR), and phosphorylated mTOR (p-mTOR) potentially contribute to necroptosis. The inhibition of RIP3 by GSK'872 (a specific inhibitor) blocked necroptosis and reduced the activity of Akt/mTOR, leading to the alleviation of inflammation by reducing the levels of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3). Moreover, the inhibition of RIP3 by GSK'872 promoted the activity of cysteinyl aspartate specific proteinase-8(Caspase-8), an enzyme involved in apoptosis and inflammation. These data demonstrate that RIP3 inhibition could improve the prognosis of TBI, based on the attenuation of inflammation by switching RIP3-dependent necroptosis to Caspase-8-dependent apoptosis.

Traumatic Brain Injury in Mice Generates Early-Stage Alzheimer's Disease Related Protein Pathology that Correlates with Neurobehavioral Deficits.

Traumatic brain injury (TBI) increases the long-term risk of neurodegenerative diseases, including Alzheimer's disease (AD). Here, we demonstrate that protein variant pathology generated in brain tissue of an experimental TBI mouse model is similar to protein variant pathology observed during early stages of AD, and that subacute accumulation of AD associated variants of amyloid beta (Aβ) and tau in the TBI mouse model correlated with behavioral deficits. Male C57BL/6 mice were subjected to midline fluid percussion injury or to sham injury, after which sensorimotor function (rotarod, neurological severity score), cognitive deficit (novel object recognition), and affective deficits (elevated plus maze, forced swim task) were assessed post-injury (DPI). Protein pathology at 7, 14, and 28 DPI was measured in multiple brain regions using an immunostain panel of reagents selectively targeting different neurodegenerative disease-related variants of Aβ, tau, TDP-43, and alpha-synuclein. Overall, TBI resulted in sensorimotor deficits and accumulation of AD-related protein variant pathology near the impact site, both of which returned to sham levels by 14 DPI. Individual mice, however, showed persistent behavioral deficits and/or accumulation of toxic protein variants at 28 DPI. Behavioral outcomes of each mouse were correlated with levels of seven different protein variants in ten brain regions at specific DPI. Out of 21 significant correlations between protein variant levels and behavioral deficits, 18 were with variants of Aβ or tau. Correlations at 28 DPI were all between a single Aβ or tau variant, both of which are strongly associated with human AD cases. These data provide a direct mechanistic link between protein pathology resulting from TBI and the hallmarks of AD.

Piezo2 Contributes to Traumatic Brain Injury by Activating the RhoA/ROCK1 Pathways.

Traumatic brain injury (TBI) can lead to short-term and long-term physical and cognitive impairments, which have significant impacts on patients, families, and society. Currently, treatment outcomes for this disease are often unsatisfactory, due at least in part to the fact that the molecular mechanisms underlying the development of TBI are largely unknown. Here, we observed significant upregulation of Piezo2, a key mechanosensitive ion channel protein, in the injured brain tissue of a mouse model of TBI induced by controlled cortical impact. Pharmacological inhibition and genetic knockdown of Piezo2 after TBI attenuated neuronal death, brain edema, brain tissue necrosis, and deficits in neural function and cognitive function. Mechanistically, the increase in Piezo2 expression contributed to TBI-induced neuronal death and subsequent production of TNF-α and IL-1β, likely through activation of the RhoA/ROCK1 pathways in the central nervous system. Our findings suggest that Piezo2 is a key player in and a potential therapeutic target for TBI.

Abstract TP312: Pharmacologically Reducing Acetylated Tau Prevents Traumatic Brain Injury-Induced Acceleration of Alzheimer’s Disease

Traumatic brain injury (TBI) afflicts 70 million people worldwide annually and is the 3rd overall risk factor for developing Alzheimer's disease (AD), behind genetics and aging. In patients with AD, a history of TBI is associated with a 3-4 year earlier onset of cognitive impairment. TBI and AD share many pathologies, including blood brain barrier dysfunction, neuroinflammation, and protein aggregation. Yet, the underlying mechanism of this relationship is not understood, and there are no treatments that protect patients from accelerated AD after TBI. We recently reported that tau, a microtubule binding protein essential for neuronal health, is acetylated after TBI. Acetylation impairs tau binding to microtubules, leading to its mis-localization into the cell soma and pathological aggregation. Acetylated tau is also elevated early in AD, and acetylated tau was significantly more elevated in the brains of human AD subjects with a history of TBI, compared to AD alone and healthy controls. Therefore, we hypothesize that TBI-induced tau acetylation drives the acceleration of AD. To study this phenomenon, we developed a mouse model of TBI that accelerates AD-like pathology and cognitive impairment in 5xFAD mice, and amyloid-driven AD model. Our unique model of multimodal TBI produces a complex and reproducible brain injury with neurodegeneration and neurobehavioral impairment, beginning with acute axonal degeneration and persisting chronically with blood-brain barrier degradation and nerve cell death. This model of TBI also produces the same systemic metabolic alterations that are reported in TBI patients. TBI causes learning deficits in young 5xFAD mice that are not seen in either sham-injured 5xFAD mice or in wild type littermates subjected to TBI. TBI also accelerates amyloid deposition in 5xFAD mice. We hypothesize that TBI will also worsen blood brain barrier function in 5xFAD mice. Importantly, 5xFAD mice show greater elevation of acetylated tau after TBI, compared to WT mice. Preliminary data suggests that treatment with the FDA-approved non-steroidal inflammatory drug diflunisal, which inhibits the enzyme that acetylates tau, reduces acetylated tau and rescues behavior deficits after TBI in 5xFAD mice.

Autophagy machinery plays an essential role in traumatic brain injury-induced apoptosis and its related behavioral abnormalities in mice: focus on Boswellia Sacra gum resin.

Traumatic brain injury (TBI) is described as a structural damage or physiological disturbance of brain function that occurs after trauma and causes disability or death in people of all ages. New treatment targets for TBI are being explored because current medicines are frequently ineffectual and poorly tolerated. There is increasing evidence that following TBI, there are widespread changes in autophagy-related proteins in both experimental and clinical settings. The current study investigated if Boswellia Sacra Gum Resin (BSR) treatment (500mg/kg) could modulate post-TBI neuronal autophagy and protein expression, as well as whether BSR could markedly improve functional recovery in a mouse model of TBI. Taken together our results shows for the first time that BSR limits histological alteration, lipid peroxidation, antioxidant, cytokines release and autophagic flux alteration induced by TBI.

Mark4 ablation attenuates pathological phenotypes in a mouse model of tauopathy.

Accumulation of abnormally phosphorylated tau proteins is linked to various neurodegenerative diseases, including Alzheimer's disease and frontotemporal dementia. Microtubule affinity-regulating kinase 4 (MARK4) has been genetically and pathologically associated with Alzheimer's disease and reported to enhance tau phosphorylation and toxicity in Drosophila and mouse traumatic brain-injury models but not in mammalian tauopathy models. To investigate the role of MARK4 in tau-mediated neuropathology, we crossed P301S tauopathy model (PS19) and Mark4 knockout mice. We performed behaviour, biochemical and histology analyses to evaluate changes in PS19 pathological phenotype with and without Mark4. Here, we demonstrated that Mark4 deletion ameliorated the tau pathology in a mouse model of tauopathy. In particular, we found that PS19 with Mark4 knockout showed improved mortality and memory compared with those bearing an intact Mark4 gene. These phenotypes were accompanied by reduced neurodegeneration and astrogliosis in response to the reduction of pathological forms of tau, such as those phosphorylated at Ser356, AT8-positive tau and thioflavin S-positive tau. Our data indicate that MARK4 critically contributes to tau-mediated neuropathology, suggesting that MARK4 inhibition may serve as a therapeutic avenue for tauopathies.

Insights from Rodent Models for Improving Bench-to-Bedside Translation in Traumatic Brain Injury.

Road accidents, domestic falls, and persons associated with sports and military services exhibited the concussion or contusion type of traumatic brain injury (TBI) that resulted in chronic traumatic encephalopathy. In some instances, these complex neurological aberrations pose severe brain damage and devastating long-term neurological sequelae. Several preclinical (rat and mouse) TBI models simulate the clinical TBI endophenotypes. Moreover, many investigational neuroprotective candidates showed promising effects in these models; however, the therapeutic success of these screening candidates has been discouraging at various stages of clinical trials. Thus, a correct selection of screening model that recapitulates the clinical neurobiology and endophenotypes of concussion or contusion is essential. Herein, we summarize the advantages and caveats of different preclinical models adopted for TBI research. We suggest that an accurate selection of experimental TBI models may improve the translational viability of the investigational entity.

Deferoxamine Induces Autophagy Following Traumatic Brain Injury via TREM2 on Microglia.

Previous studies have indicated that iron disorder, inflammation, and autophagy play an important role in traumatic brain injury (TBI). The triggering receptor expressed on myeloid cells 2 (TREM2), an immunoglobulin superfamily transmembrane receptor, is involved in inflammation. However, the role of TREM2 in modulating the microglia response in TBI has been rarely investigated. The present study aimed to investigate if the iron chelator deferoxamine (DFO) could ameliorate TBI through autophagy mediated by the TREM2. TBI was developed by the controlled cortical impact (CCI) mouse model and stretching of individual primary cortical microglia taken from the tissue of the rat brain. DFO was intraperitoneally used for intervention. Western blotting assay, qRT-PCR, TUNEL staining, immunofluorescence staining, confocal microscopy analysis, transmission electron microscopy, H&E staining, brain water content measurement, and the neurobehavioral assessments were performed. TREM2 expression was up-regulated in cortex of TBI mice model and in microglia stretching model, which was attenuated by DFO. After the mice were subjected to CCI, DFO treatment significantly up-regulated the protein levels of autophagy compared with the TBI group at 3days and caused an increase of autophagic vacuoles. Treatment with DFO reduced TBI-induced cell apoptosis, cerebral edema, neuroinflammation, and motor function impairment in mice, at least partly via the mTOR signaling pathway that facilitates the TREM2 activity. The results indicated that the maintenance of iron homeostasis by DFO plays neuroprotection by modulating the inflammatory response to TBI through TREM2-mediated autophagy. This study suggested that TREM2-mediated autophagy might be a potential target for therapeutic intervention in TBI.

Screening of potent RIPK3 inhibitors to attenuate necroptosis and inflammation in mouse traumatic brain injury models

Necroptosis is a type of cell death that occurs when cells are exposed to external stressors such as inflammation, infections, or injury. In necroptosis, cells use a different set of proteins including: receptor-interacting kinase 1 (RIPK1 or RIP1), receptor-interacting kinase 3 (RIPK3 or RIP3) and the phosphorylation of its substrate mixed lineage kinase domain-like protein (MLKL) and pathways to trigger their own death. Mutations in the gene encoding RIPK3 have been associated with many diseases, including neurodegenerative diseases, neuroinflammatory diseases, inflammatory diseases，tumors, and it is being studied as a potential target for inflammatory injury therapy. RIPK3 has also been implicated in the pathology of neuroinflammation following Traumatic brain injury and is currently being explored as a potential therapy. We screened through necroptosis blocking compounds, a library of FDA-approved compounds. We found four compounds:1D6-Foretinib GSK1363089; 15F6-Poziotinib (HM781-36B); 15F9-Dasatinib monohydrate; 15A10-Pexmetinib (ARRY-614); acts as potent inhibitors of necroptosis (Necroptosis Blocking Compounds, NBCs) by blocking the RIPK3 kinase activity. These four compounds effectively block necroptosis induced by death receptor ligands Toll-like receptors as well as viral infections in human, rat and mouse cells. The cellular activation of RIPK3 and MLKL stimulated by necroptosis was strongly inhibited by NBCs. The compounds are promising for targeting RIPK3 kinase activity, thereby preventing necroptosis and inflammatory responses. In our study, we explored the role of NBCs in neuroprotection after traumatic brain injury. It's effectiveness in traumatic brain injury animal models and favorable safety profiles make it a potential candidate for the advances of new therapies for necroptosis-associated neuroinflammatory disorders.

Aging drives chronic exacerbated interactions of disease associated microglia and CD8+ T cells following traumatic brain injury

AbstractBackgroundAged individuals are highly susceptible to adverse outcomes following traumatic brain injury (TBI). Despite worsened correlates related to functional outcomes following injury, as well as increased likelihood to acquire a TBI, our understanding of the cellular mechanisms governing the poorer outcomes associated with aged individuals post‐TBI are not well‐characterized.MethodIn the current study, we examined microglial heterogeneity following TBI, in our mouse model of focal TBI across both acute (3d) and chronic (28d) intervals in both young (4m) and aged (18m) male C57B6J mice. At the appropriate interval, brains were collected and processed for single cell RNAseq (scRNAseq), spatial transcriptomics, and histology. A follow up study examining the interaction of TBI and aging upon T cell receptor (TCR) sequences was utilized to examine clonal expansion and lymphocyte heterogeneity in young and aged mice chronically after TBI.ResultOur findings demonstrate that TBI drives diverse transcriptional heterogeneity of microglia in both the young and aged condition. Acutely at 3 days post injury an inflammatory response is seen both in the young and aged mice. However, chronically at 28 days post injury, the microglia from young animals more closely resemble their pre‐injury (i.e. Sham) phenotypes, in comparison to the aged brain where there is a persistence of Apoe‐linked ‘DAM‐like’ microglial response. Inferential analyses point toward these aging‐related chronic populations of microglia as having distinct transcription factor utilization and metabolic pathway enrichment, including Hif1α upregulation and interferon gamma (INFγ) signaling. Furthermore, linkage with chronically accumulated CD8+ T cells and interferon signaling may underlie these phenotypes. Using single cell TCR sequencing, we demonstrate stark contrasts in the responses due to aging and TBI in the clonal expansion of infiltrated CD8+ T cells chronically following TBI.ConclusionOur studies demonstrate that aging is a centrally associated with the persistence of chronically reactive microglia in the brain and that these responses are linked, in part, with the protracted accumulation of CD8+ T cells following TBI.

Oxyberberine an oxoderivative of berberine confers neuroprotective effects in controlled-cortical impact mouse model of traumatic brain injury

Background Traumatic brain injury (TBI) is known as a silent epidemic that causes many deaths and disabilities worldwide. We examined the response of oxyberberine (OBB) in lipopolysaccharide-stimulated BV2 microglial cells and a controlled-cortical impact (CCI) mouse model of TBI. Methods We synthesized OBB from berberine, and also prepared OBB-nanocrystals (OBB-NC). Male C57BL/6 mice were used for CCI surgery, and post-CCI neurobehavioral deficits were assessed from 1 h after injury through 21 days post-injury (dpi). Results OBB treatment reduced the lipopolysaccharide-triggered elevated levels of reactive oxygen species, nitric oxide, and nuclear factor kappa B (NF-κB) in BV2 microglial cells, indicating a neuroprotective potential. CCI-operated mice exhibited significant neurological deficits on 1, 3, and 5 dpi in neurological severity scoring and rotarod assay. OBB (25 and 50 mg/kg/day) and OBB-NC (3 mg/kg/day) ameliorated these neurological aberrations. Mice subjected to CCI surgery also displayed anxiogenic- and depression-like behaviours, and cognitive impairments in forced-swimming test and elevated-zero maze, and novel object recognition task, respectively. Administration of OBB reduced these long-term neuropsychiatric complications, and also levels of toll-like receptor 4 (TLR4), high-motility group protein 1 (HMGB1), NF-κB, tumour necrosis factor-alpha and interleukin 6 cytokines in the ipsilateral cortex of mice. Conclusion We suggest that the administration of OBB offers neuroprotective effects via inhibition of HMGB1-mediated TLR4/NFκB pathway.

Selective inhibition of soluble TNF using XPro1595 improves hippocampal pathology to promote improved neurological recovery following traumatic brain injury in mice.

To determine the efficacy of XPro1595 to improve pathophysiological and functional outcomes in a mouse model of traumatic brain injury (TBI). Symptoms associated with TBI can be debilitating, and treatment without off-target side effects remains a challenge. This study aimed to investigate the efficacy of selectively inhibiting the soluble form of TNF (solTNF) using the biologic XPro1595 in a mouse model of TBI. Use XPro1595 to determine whether injury-induced solTNF promotes hippocampal inflammation and dendritic plasticity, and associated functional impairments. Mild-to-moderate traumatic brain injury (CCI model) was induced in adult male C57Bl/6J WT and Thy1-YFPH mice, with XPro1595 (10 mg/kg, S.C.) or vehicle being administered in a clinically relevant window (60 minutes post-injury). The animals were assessed for differences in neurological function, and hippocampal tissue was analyzed for inflammation and glial reactivity, as well as neuronal degeneration and plasticity. We report that unilateral CCI over the right parietal cortex in mice promoted deficits in learning and memory, depressive-like behavior, and neuropathic pain. Using immunohistochemical and Western blotting techniques, we observed the cortical injury promoted a set of expected pathophysiology's within the hippocampus consistent with the observed neurological outcomes, including glial reactivity, enhanced neuronal dendritic degeneration (dendritic beading), and reduced synaptic plasticity (spine density and PSD-95 expression) within the DG and CA1 region of the hippocampus, that were prevented in mice treated with XPro1595. Overall, we observed that selectively inhibiting solTNF using XPro1595 improved the pathophysiological and neurological sequelae of brain-injured mice, which provides support for its use in patients with TBI.

Long-term results on the suppression of secondary brain injury by early administered low-dose baclofen in a traumatic brain injury mouse model

Secondary injury from traumatic brain injury (TBI) perpetuates cerebral damages through varied ways. Attenuating neuroinflammation, which is a key feature of TBI, is important for long-term prognosis of its patients. Baclofen, a muscle relaxant, has shown promise in reducing excessive inflammation in other neurologic disorders. However, its effectiveness in TBI remains ambiguous. Thus, our study aimed to investigate whether early administration of baclofen could elicit potential therapeutic effects by diminishing exaggerated neuroinflammation in TBI mice. In this study, 80 C57BL/6 mice were used, of which 69 mice received controlled cortical impact. The mice were divided into six groups (11–16 mice each). Baclofen, administered at dose of 0.05, 0.2 and 1 mg/kg, was injected intraperitoneally a day after TBI for 3 consecutive weeks. 3 weeks after completing the treatments, the mice were assessed histologically. The results showed that mice treated with baclofen exhibited a significantly lower volume of lesion tissue than TBI mice with normal saline. Baclofen also reduced activated glial cells with neurotoxic immune molecules and inhibited apoptotic cells. Significant recovery was observed and sustained for 6 weeks at the 0.2 mg/kg dose in the modified neurological severity score. Furthermore, memory impairment was recovered with low-doses of baclofen in the Y-maze. Our findings demonstrate that early administration of low dose baclofen can regulate neuroinflammation, prevent cell death, and improve TBI motor and cognitive abnormalities.

Astrocyte-targeted siRNA delivery by adenosine-functionalized LNP in mouse TBI model

Traumatic brain injury (TBI) induces pro-inflammatory polarization of astrocytes and causes secondary disruption of the blood-brain barrier (BBB) and brain damage. Herein, we report a successful astrocyte-targeted delivery of small interfering RNA (siRNA) by ligand functionalized lipid nanoparticles (LNPs) formulated from adenosine-conjugated lipids and a novel ionizable lipid (denoted by Ad4 LNPs). Systemic administration of Ad4 LNPs carrying siRNA against TLR4 to the mice TBI model resulted in the specific internalization of the LNPs by astrocytes in the vicinity of damaged brain tissue. A substantial knockdown of TLR4 at both mRNA and protein levels in the brain was observed, which led to a significant decrease of key pro-inflammatory cytokines and an increase of key anti-inflammatory cytokines in serum. Dye leakage measurement suggested that the Ad4-LNP-mediated knockdown of TLR4 attenuated the TBI-induced BBB disruption. Together, our data suggest that Ad4 LNP is a promising vehicle for astrocyte-specific delivery of nucleic acid therapeutics.