IKK2/NF-κB signaling protects neurons after traumatic brain injury

Glial cells react to closed head injury in a distinct and spatiotemporally orchestrated manner

Traumatic brain injury (TBI) is a leading cause of mortality and disability worldwide. Acute neuroinflammation is a prominent reaction after TBI and is mostly initiated by brain-resident glial cells such as microglia, NG2-glia and astrocytes. The magnitude of this reaction paves the way for long-lasting consequences such as chronic neurological pathologies, for which therapeutic options remain limited. The neuroinflammatory response to TBI is mostly studied with craniotomy-based animal models that are very robust but also rather artificial. Here, we aimed to analyze the reaction of glial cells in a highly translational but variable closed head injury (CHI) model and were able to correlate the severity of the trauma to the degree of glial response. Furthermore, we could show that the different glial cell types react in a temporally and spatially orchestrated manner in terms of morphological changes, proliferation, and cell numbers in the first 15 days after the lesion. Interestingly, NG2-glia, the only proliferating cells in the healthy brain parenchyma, divided at a rate that was correlated with the size of the injury. Our findings describe the previously uncharacterized posttraumatic response of the major brain glial cell types in CHI in order to gain a detailed understanding of the course of neuroinflammatory events; such knowledge may open novel avenues for future therapeutic approaches in TBI.

Interplay of G-proteins and Serotonin in the Neuroimmunoinflammatory Model of Chronic Stress and Depression: A Narrative Review

INTRODUCTION

This narrative review addresses the clinical challenges in stress-related disorders such as depression, focusing on the interplay between neuron-specific and pro-inflammatory mechanisms at the cellular, cerebral, and systemic levels.

OBJECTIVE

We aim to elucidate the molecular mechanisms linking chronic psychological stress with low-grade neuroinflammation in key brain regions, particularly focusing on the roles of G proteins and serotonin (5-HT) receptors.

METHODS

This comprehensive review of the literature employs systematic, narrative, and scoping review methodologies, combined with systemic approaches to general pathology. It synthesizes current research on shared signaling pathways involved in stress responses and neuroinflammation, including calcium-dependent mechanisms, mitogen-activated protein kinases, and key transcription factors like NF-κB and p53. The review also focuses on the role of G protein-coupled neurotransmitter receptors (GPCRs) in immune and pro-inflammatory responses, with a detailed analysis of how 13 of 14 types of human 5-HT receptors contribute to depression and neuroinflammation.

RESULTS

The review reveals a complex interaction between neurotransmitter signals and immunoinflammatory responses in stress-related pathologies. It highlights the role of GPCRs and canonical inflammatory mediators in influencing both pathological and physiological processes in nervous tissue.

CONCLUSION

The proposed Neuroimmunoinflammatory Stress Model (NIIS Model) suggests that proinflammatory signaling pathways, mediated by metabotropic and ionotropic neurotransmitter receptors, are crucial for maintaining neuronal homeostasis. Chronic mental stress can disrupt this balance, leading to increased pro-inflammatory states in the brain and contributing to neuropsychiatric and psychosomatic disorders, including depression. This model integrates traditional theories on depression pathogenesis, offering a comprehensive understanding of the multifaceted nature of the condition.

Dexmedetomidine Protects Cortical Neurons from Propofol-Induced Apoptosis via Activation of Akt-IKK-NF-κB Signaling Pathway by α2A-adrenoceptor

CONTEXT

Propofol can induce neuroapoptosis. It has been reported that dexmedetomidine (DEX) has a protective effect on propofol-induced neuroapoptosis, but the specific mechanism needs to be further explored to provide a theoretical basis for their combined use.

OBJECTIVE

We aimed to explore the neuroprotective effect of DEX on primary cortical neurons treated by propofol and to elucidate the underlying mechanistic pathways.

METHODS

Cortical neurons were isolated from fetal rats and treated with propofol. MTT assays were performed to detect cell viability, α-tubulin immunofluorescent assays were conducted to observe cell abnormalities, and c-caspase3 immunofluorescent assays and flow cytometry were performed to examine cell apoptosis. Further, neurons were cotreated with propofol and DEX to study DEX's neuroprotective effects on propofol-caused neuronal injuries. Finally, the α2A-adrenoceptor was knocked out and/or the Akt activator (SC-79) was added to cells co-treated with propofol and DEX. The expression levels of Akt-IKK-NF-κB pathway-related proteins were detected by western blot.

RESULTS

Propofol decreased cell viability in a dose-dependent manner, triggered apoptosis, caused morphological abnormalities and down-regulated the phosphorylation levels of Akt, IKK, NF-κB and IκB in cortical neurons. DEX ameliorated the decrease of cell viability, alleviated neuronal apoptosis and promoted the downregulated expression levels of p-Akt, IKK, NF-κB, and IκB proteins which had been induced by propofol treatment. Western blot findings following the transfection of α2A-siRNA and the addition of SC-79 suggested that DEX's neuroprotective functions arose from the stimulation of α2A-adrenoceptors to activate the Akt-IKK-NF-κB signal pathway.

CONCLUSION

DEX protected neurons against propofol-induced apoptosis via activation of the Akt-IKK-NF-κB signal pathway through α2A-adrenoceptors.

Electroacupuncture regulates microglial polarization via inhibiting NF-κB/COX2 pathway following traumatic brain injury

BACKGROUND

Neuroinflammation and oxidative stress are important pathological mechanisms following traumatic brain injury (TBI). The NF-κB/COX2 pathway regulates neuroinflammation and oxidative damage, while microglia also play an important role in neuroinflammation. Since NF-κB is involved in microglial polarization, targeting this pathway and microglial polarization is a critical component of TBI treatment. Currently, electroacupuncture (EA) is widely used to treat various symptoms after TBI, but the mechanisms of EA remain poorly understood. Additionally, the optimal frequency of EA remains unclear, which affects its efficacy. This study focuses on exploring the optimal frequency parameters of EA on TBI and investigating the underlying mechanisms of EA through NF-κB/COX2 pathway and microglial polarization.

METHODS

The study was divided into two parts. In Experiment 1, 42 Sprague Dawley (SD) rats were induced and randomly divided into seven groups (n = 6). Except for the sham group, all rats underwent controlled cortical impact (CCI) to establish TBI model. Four EA groups (with different frequencies) and manual acupuncture (without current stimulation) received stimulation on the acupoints of Shuigou (GV26), Fengchi (GB20) and Neiguan (PC6) once a day for 7 days. The neurological function was assessed by modified Neurological Severity Scores (mNSS), and the rats' memory and learning were examined by the Morris water maze (MWM). SOD, MDA, and GSH-Px were detected to evaluate the levels of oxidative stress. The levels of IL-1β, IL-6, and TNF-α were evaluated by Enzyme Linked Immunosorbent Assay (ELISA). Detection of the above indicators indicated a treatment group that exerted the strongest neuroprotection against TBI, we then conducted Experiment 2 using this screened acupuncture treatment to investigate the mechanism of acupuncture. 48 rats were randomly divided into four groups (n = 12): sham, TBI model, acupuncture and PDTC (NF-κB inhibitor). Evaluations of mNSS, MWM test, SOD, MDA, GSH-Px, IL-1β, IL-6, TNF-α, and IL-10 were the same as in Experiment 1. Western blot was applied for detecting the expression levels of NF-κB, p-NF-κB, COX2, and Arg-1. TUNEL was used to examine neuronal apoptosis. Brain structure was observed by H&E. Iba-1, COX2, and Arg-1 were investigated by immunofluorescence staining.

RESULTS

EA with frequency of 2/100 Hz markedly improved neuronal and cognitive function as compared to the other treatment groups. Moreover, it downregulated the expression of MDA, IL-6, IL-1β, and TNF-α and upregulated the levels of SOD and GSH-Px. In addition, Both EA with 2/100 Hz and PDTC reduced the levels of p-NF-κB, COX2 and M1 markers (COX2, IL-6, IL-1β, TNF-α) and increased the levels of M2 markers (Arg-1, IL-10). Moreover, they had similar effects on reducing inflammation, oxidative stress and apoptosis, and improving neuronal and cognitive function.

CONCLUSIONS

The collective findings strongly suggest that EA with 2/100 Hz can improve neurologic function by suppressing neuroinflammation, oxidative stress and apoptosis. Additionally, we confirm that EA promotes microglial polarization towards the M2 phenotype through the suppression of NF-κB/COX2 pathway, thus exerting neuroprotective effects after TBI.

The Effect of Simvastatin on the Dynamics of NF-κB-Regulated Neurodegenerative and Neuroprotective Processes in the Acute Phase of Ischemic Stroke

Statins are lipid-lowering drugs that act by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A reductase, a rate-limiting enzyme in cholesterol biosynthesis. Animal studies have shown neuroprotective effects of statins in cerebral stroke. However, the underlying mechanisms are not fully understood. The nuclear factor-kappa B (NF-κB) transcription factor is involved in the regulation of apoptosis in stroke. Different dimers of NF-κB regulate the gene expression of proteins involved in both neurodegeneration and neuroprotection. We aimed to determine whether simvastatin improves stroke outcome via inhibition of the RelA/p65-containing subunit and downregulation of stroke-induced pro-apoptotic genes or via activation of NF-κB dimers containing the c-Rel subunit and upregulation of anti-apoptotic genes during the acute stroke phase. Eighteen-month-old Wistar rats, subjected to permanent MCAO or sham surgery, were administered simvastatin (20 mg/kg b.w.) or saline for 5 days before the procedure. Stroke outcome was determined by measuring cerebral infarct and assessing motor functions. The expression of NF-κB subunits in various cell populations was investigated using immunofluorescence/confocal microscopy. RelA and c-Rel were detected by WB. The NF-κB-DNA binding activity was investigated using EMSA, and expression of Noxa, Puma, Bcl-2, and Bcl-x genes was analyzed by qRT-PCR. Results showed a 50% infarct size reduction and significant motor function improvement in the simvastatin-treated animals which correlated with a decrease in RelA and a transient increase in the c-Rel level in the nucleus, normalization of the NF-κB-DNA binding activity, and downregulation of the NF-κB-regulated genes. Our results provide new insights into the statin-mediated neuroprotective action against stroke based on NF-κB pathway inhibition.

Inhibiting phosphatase and actin regulator 1 expression is neuroprotective in the context of traumatic brain injury

Studies have found that the phosphatase actin regulatory factor 1 expression can be related to stroke, but it remains unclear whether changes in phosphatase actin regulatory factor 1 expression also play a role in traumatic brain injury. In this study we found that, in a mouse model of traumatic brain injury induced by controlled cortical impact, phosphatase actin regulatory factor 1 expression is increased in endothelial cells, neurons, astrocytes, and microglia. When we overexpressed phosphatase actin regulatory factor 1 by injection an adeno-associated virus vector into the contused area in the traumatic brain injury mice, the water content of the brain tissue increased. However, when phosphatase actin regulatory factor 1 was knocked down, the water content decreased. We also found that inhibiting phosphatase actin regulatory factor 1 expression regulated the nuclear factor kappa B signaling pathway, decreased blood-brain barrier permeability, reduced aquaporin 4 and intercellular adhesion molecule 1 expression, inhibited neuroinflammation, and neuronal apoptosis, thereby improving neurological function. The findings from this study indicate that phosphatase actin regulatory factor 1 may be a potential therapeutic target for traumatic brain injury.

Research progress of neuroinflammation-related cells in traumatic brain injury: A review

Neuroinflammation after traumatic brain injury (TBI) is related to chronic neurodegenerative diseases and is one of the causes of acute secondary injury after TBI. Therefore, it is particularly important to clarify the role of cellular mechanisms in the neuroinflammatory response after TBI. The objective of this article is to understand the involvement of cells during the TBI inflammatory response (for instance, astrocytes, microglia, and oligodendrocytes) and shed light on the recent progress in the stimulation and interaction of granulocytes and lymphocytes, to provide a novel approach for clinical research. We searched articles in PubMed published between 1950 and 2023, using the following keywords: TBI, neuroinflammation, inflammatory cells, neuroprotection, clinical. Articles for inclusion in this paper were finalized based on their novelty, representativeness, and relevance to the main arguments of this review. We found that the neuroinflammatory response after TBI includes the activation of glial cells, the release of inflammatory mediators in the brain, and the recruitment of peripheral immune cells. These inflammatory responses not only induce secondary brain damage, but also have a role in repairing the nervous system to some extent. However, not all of the mechanisms of cell-to-cell interactions have been well studied. After TBI, clinical treatment cannot simply suppress the inflammatory response, and the inflammatory phenotype of patients' needs to be defined according to their specific conditions after injury. Clinical trials of personalized inflammation regulation therapy for specific patients should be carried out in order to improve the prognosis of patients.

CASP8 Is a Potential Therapeutic Target and Is Correlated with Pyroptosis in Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) is a major cause of neurological and psychological problems, especially long-term disability. The purpose of this article is to explore molecular mechanisms linking TBI and pyroptosis with the aim of providing a promising target for future therapeutic interventions.

METHODS

GSE104687 microarray dataset was downloaded from the Gene Expression Omnibus database to obtain differential expressed genes. Meanwhile, pyroptosis-related genes were screened from GeneCards database, and the overlapped genes were considered as the pyroptosis-related genes in TBI. The immune infiltration analysis was conducted to quantify lymphocyte infiltration levels. Moreover, we researched the relevant microRNAs (miRNAs) and transcription factors and investigated the interactions and functions of miRNAs. In addition, the validation set and in vivo experiment further verified the expression of hub gene.

RESULTS

Altogether, we found 240 differential expressed genes in GSE104687 and 254 pyroptosis-related genes in the GeneCards database, and the overlapped gene was caspase 8 (CASP8). Immune Infiltration Analysis suggested the abundance of Tregs cells was significantly higher in TBI group. The NKT and CD8+ Tem were positively correlated with the expression levels of CASP8. The most significant term regarding CASP8 in Reactome pathways analysis was related to NF-kappaB. A total of 20 miRNAs and 25 transcription factors associated with CASP8 were obtained. After investigating the interactions and functions of miRNAs, the NF-kappaB-related signaling pathway was still enriched with a relatively low P-value. The validation set and in vivo experiment further verified the expression of CASP8.

CONCLUSIONS

Our study showed the potential role of CASP8 in pathogenesis of TBI, which may provide a new target for individualized therapy and drug development.

The therapeutic potential of the neuroactive peptides of soluble amyloid precursor protein-alpha in Alzheimer's disease and related neurological disorders

Soluble amyloid precursor protein-alpha (sAPPα) is a multi-functional brain-derived protein that has neuroprotective, neurogenic and neurotropic properties. Moreover, it is known to facilitate synaptic function and promote neural repair. These properties suggest sAPPα may be useful as a therapeutic agent for the treatment of neurological diseases characterized by synaptic failure and neuronal loss, such as occurs in Alzheimer's disease, and for neural repair following traumatic brain injury and stroke. However, sAPPα's relatively large size and the difficulty of ongoing delivery of therapeutics to the brain mean this is not currently practicable. Importantly, however, sAPPα is composed of several neuroactive domains that each possess properties that collectively are remarkably similar to those of sAPPα itself. Here, we review the molecular structure of sAPPα and identify the domains that contribute to its overall functionality. Four peptide motifs present as possible targets for therapeutic development. We review their physiochemical and neuroactive properties, both within sAPPα and as isolated peptides, and discuss their potential for future development as multipurpose therapeutic agents for the treatment of Alzheimer's disease and other disorders of neuronal function. Further, we discuss the role of heparin binding sites, found within sAPPα's structure and overlapping with the neuroactive domains, as sites for interactions with effector proteins and synaptic receptors. The potential role of the neuroactive peptides known as Cationic Arginine-Rich Peptides (CARPs) as neuroprotective motifs is also reviewed. Mechanisms of peptide delivery to the brain are briefly discussed. Finally, we summarise the potential benefits and pitfalls of using the isolated peptides, either individually or in combination, for the treatment of neurological diseases.

Deficiency of IKKβ in neurons ameliorates Alzheimer's disease pathology in APP- and tau-transgenic mice

In Alzheimer's disease (AD) brain, inflammatory activation regulates protein levels of amyloid-β-peptide (Aβ) and phosphorylated tau (p-tau), as well as neurodegeneration; however, the regulatory mechanisms remain unclear. We constructed APP- and tau-transgenic AD mice with deletion of IKKβ specifically in neurons, and observed that IKKβ deficiency reduced cerebral Aβ and p-tau, and modified inflammatory activation in both AD mice. However, neuronal deficiency of IKKβ decreased apoptosis and maintained synaptic proteins (e.g., PSD-95 and Munc18-1) in the brain and improved cognitive function only in APP-transgenic mice, but not in tau-transgenic mice. Additionally, IKKβ deficiency decreased BACE1 protein and activity in APP-transgenic mouse brain and cultured SH-SY5Y cells. IKKβ deficiency increased expression of PP2A catalytic subunit isoform A, an enzyme dephosphorylating cerebral p-tau, in the brain of tau-transgenic mice. Interestingly, deficiency of IKKβ in neurons enhanced autophagy as indicated by the increased ratio of LC3B-II/I in brains of both APP- and tau-transgenic mice. Thus, IKKβ deficiency in neurons ameliorates AD-associated pathology in APP- and tau-transgenic mice, perhaps by decreasing Aβ production, increasing p-tau dephosphorylation, and promoting autophagy-mediated degradation of BACE1 and p-tau aggregates in the brain. However, IKKβ deficiency differently protects neurons in APP- and tau-transgenic mice. Further studies are needed, particularly in the context of interaction between Aβ and p-tau, before IKKβ/NF-κB can be targeted for AD therapies.

Nanoparticle-based drug delivery for the treatment of traumatic brain injury

INTRODUCTION

Traumatic brain injuries (TBIs) impact the breadth of society and remain without any approved pharmacological treatments. Despite successful Phase II clinical trials, the failure of many Phase III clinical trials may be explained by insufficient drug targeting and retention, preventing the proper attainment of an observable dosage threshold. To address this challenge, nanoparticles can be functionalized to protect pharmacological payloads, improve targeted drug delivery to sites of injury, and can be combined with supportive scaffolding to improve secondary outcomes.

AREAS COVERED

This review briefly covers the pathophysiology of TBIs and their subtypes, the current pre-clinical and clinical management strategies, explores the common models of focal, diffuse, and mixed traumatic brain injury employed in experimental animals, and surveys the existing literature on nanoparticles developed to treat TBIs.

EXPERT OPINION

Nanoparticles are well suited to improve secondary outcomes as their multifunctionality and customizability enhance their potential for efficient targeted delivery, payload protection, increased brain penetration, low off-target toxicity, and biocompatibility in both acute and chronic timescales.

Mesenchymal Stem Cell Therapy: A Potential Treatment Targeting Pathological Manifestations of Traumatic Brain Injury

Traumatic brain injury (TBI) makes up a large proportion of acute brain injuries and is a major cause of disability globally. Its complicated etiology and pathogenesis mainly include primary injury and secondary injury over time, which can cause cognitive deficits, physical disabilities, mood changes, and impaired verbal communication. Recently, mesenchymal stromal cell- (MSC-) based therapy has shown significant therapeutic potential to target TBI-induced pathological processes, such as oxidative stress, neuroinflammation, apoptosis, and mitochondrial dysfunction. In this review, we discuss the main pathological processes of TBI and summarize the underlying mechanisms of MSC-based TBI treatment. We also discuss research progress in the field of MSC therapy in TBI as well as major shortcomings and the great potential shown.

Involvement of Nuclear Factor-κB in Inflammation and Neuronal Plasticity Associated with Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric condition which develops either due to stress or witnessing a traumatic situation. PTSD is characterized by acute and chronic stress response exhibit anxiety, fear, and an increased inflammatory etiology. Inflammation contributes a critical role in several parts of the brain that control fear and flashback cognatic function. It is known that impairment of the neurological circuit leads to the development of PTSD. Evidence has suggested that dysregulation of the sympathetic nervous system and hypothalamic-pituitary adrenal (HPA) axis and inflammatory responsiveness are pivotal and a greater risk in PTSD. NF-κB, a master regulator for inflammation, has been showed to modulate memory reconsolidation and synaptic plasticity; however, NF-κB’s association with PTSD remain elusive. In this review, we provide relevant findings regarding NF-κB activity in various components of brain and describe a potential mechanism linking PTSD using preclinical and clinical models. We envisage NF-κB signaling as a crucial mediator for inflammation, cognitive function, memory restoration and behavioral actions of stress and suggest that it could be used for therapeutic intervention in PTSD.

Integrated Network Pharmacology and UPLC/Q-TOF-MS Screen System to Exploring Anti-Inflammatory Active Components and Mechanism of Shunaoxin Pills

Background

Chronic cerebral ischemia (CCI) is a pathological condition associated with a variety of cerebrovascular diseases. Shunaoxin pills (SNX) are a traditional Chinese medicine (TCM) used to improve blood circulation. However, its multicomponent and multitarget features make it difficult to decipher the molecular mechanisms.

Objective

Thus, in this study, we aimed to identify the key anti-inflammatory components of SNX as markers for standardization and quality control and the potential pharmacological mechanisms of SNX in the treatment of CCI by network pharmacology to provide scientific evidence of its clinical efficacy.

Methods

We evaluated the anti-inflammatory effect of SNX using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectroscopy (UPLC/Q-TOF-MS) combined with a dual-luciferase reporter assay for nuclear factor kappa B (NF-κB) inhibition to identify the active components in SNX. In addition, key pathways involved in the anti-inflammatory effect of SNX were predicted using a network pharmacology approach, and some crucial proteins and pathways were further validated by Western blotting.

Results

Shunaoxin pills inhibited NF-κB through tumor necrosis factor-α (TNF-α) stimulation in 293T cells. The therapeutic effect may be related to 10 pathways regulated by ligustilide, ferulic acid, ligustrazine, and senkyunolide I. It was further confirmed that ligustilide could reduce the inflammatory response by inhibiting the phosphorylation of p38 and 3-phosphoinositide-dependent kinase 1 (PDK1).

Conclusions

Ligustilide, senkyunolide I, ferulic acid, and ligustrazine could be used as anti-inflammatory Q-markers to control the quality of SNX, and p38 and PDK1 might be potential targets of SNX in the treatment of CCI.

Microglial NF-κB drives tau spreading and toxicity in a mouse model of tauopathy

Activation of microglia is a prominent pathological feature in tauopathies, including Alzheimer's disease. How microglia activation contributes to tau toxicity remains largely unknown. Here we show that nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, activated by tau, drives microglial-mediated tau propagation and toxicity. Constitutive activation of microglial NF-κB exacerbated, while inactivation diminished, tau seeding and spreading in young PS19 mice. Inhibition of NF-κB activation enhanced the retention while reduced the release of internalized pathogenic tau fibrils from primary microglia and rescued microglial autophagy deficits. Inhibition of microglial NF-κB in aged PS19 mice rescued tau-mediated learning and memory deficits, restored overall transcriptomic changes while increasing neuronal tau inclusions. Single cell RNA-seq revealed that tau-associated disease states in microglia were diminished by NF-κB inactivation and further transformed by constitutive NF-κB activation. Our study establishes a role for microglial NF-κB signaling in mediating tau spreading and toxicity in tauopathy.

Propofol rescued astrocytes from LPS-induced inflammatory response via blocking LncRNA-MEG3/NF-κB axis

OBJECTIVE

Evidences had demonstrated that propofol attenuated neuro-inflammation following brain ischemia. Moreover, LncRNA-MEG3 was identified as an independent prognostic marker for ischemic stroke patients, and was found to be correlated with cerebral ischemia in animal models. Therefore, the current study explored the role of propofol on lipopolysaccharide (LPS)-mediated inflammation in cultured astrocytes, along with the molecular mechanism involved in LncRNA-MEG3/NF-κB axis.

METHODS

The primary cultured astrocytes isolated from rats were used to establish an inflammatory model, which were treated with LPS. Propofol was administrated to the primary cultured astrocytes during LPS treatment. The effect of propofol on pro-inflammatory cytokines and the LncRNA-MEG3/NF-κB pathway were detected by ELISA, qRT-PCR and Western Blot assay, respectively. Then, dual-luciferase assay, chromatin immunoprecipitation and RNA immunoprecipitation were used to determine the interaction between LncRNA-MEG3 and NF-κB.

RESULTS

Our study found that propofol significantly reduced LncRNA-MEG3 expression, which was elevated in LPS-stimulated astrocytes. Moreover, both propofol and LncRNA-MEG3 knockdown remarkably alleviated LPS-induced cytotoxicity by suppressing expressions and release of pro-inflammatory cytokines. Loss of LncRNA-MEG3 notably suppressed the NF-κB activity and its phosphorylated activation. Additionally, it was also observed that LncRNA-MEG3 could bind nuclear p65/p50, and promote the binding of NF-κB to IL-6 and TNF-α promoters in the nucleus, subsequently stimulating the production of inflammatory cytokines in LPS-treated astrocytes. Furthermore, a specific inhibitor of NF-κB, PDTC rescued astrocytes from LPS exposure without affecting LncRNA-MEG3 expression.

CONCLUSION

These findings demonstrated that LncRNA-MEG3 acted as a positive regulator of NF-κB, mediated the neuroprotection of propofol in LPS-triggered astrocytes injury.

Vitamin D as therapeutic modulator in cerebrovascular diseases: a mechanistic perspectives

Vitamin D deficiency has been linked to several major chronic diseases, such as cardiovascular and neurodegenerative diseases, diabetes, and cancer, linked to oxidative stress, inflammation, and aging. Vitamin D deficiency appears to be particularly harmful to the cardiovascular system, as it can cause endothelial dysfunctioning and vascular abnormalities through the modulation of various downstream mechanisms. As a result, new research indicates that therapeutic approaches targeting vitamin D inadequacies or its significant downstream effects, such as impaired autophagy, abnormal pro-inflammatory and pro-oxidant reactions, may delay the onset and severity of major cerebrovascular disorders such as stroke and neurologic malformations. Vitamin D modulates the various molecular pathways, i.e., Nitric Oxide, PI3K-Akt Pathway, cAMP pathway, NF-kB Pathway, Sirtuin 1, Nrf2, FOXO, in cerebrovascular disorder. The current review shows evidence for vitamin D's mitigating or slowing the progression of these cerebrovascular disorders, which are significant causes of disability and death worldwide.

Ozone treatment alleviates brain injury in cerebral ischemic rats by inhibiting the NF-κB signaling pathway and autophagy

Stroke is the most frequent cause of disability in developed countries. A common phenomenon of stroke, cerebral ischemia, is threatening many lives worldwide. In addition, ozone treatment was previously reported to exert functions in relieving brain injury. In the current study, the therapeutic effects of ozone on cerebral ischemia are investigated. A rat model of middle cerebral artery occlusion (MCAO) was established. The brain water content was calculated by weighing brain tissues, and the 2, 3, 5-triphenyltetrazolium chloride staining was performed to measure brain infarction volume in rats. A colorimetric assay was conducted to examine expression levels of malondialdehyde, superoxide dismutase, catalase, and glutathione in the rat hippocampus. Reverse transcription quantitative polymerase-chain reaction and Western blot analyses were employed to evaluate expression levels of Beclin1, LC3B, p62, and critical factors implicated in the NF-κB signaling pathway. We found that ozone significantly improved the survival rate of MCAO model rats, reduced the cerebral water content, and decreased the neurological scores of ischemic rats. Ozone markedly reduced cerebral ischemia-induced infarction in ischemic rats. Ozone decreased MDA levels and increased SOD, catalase, and GSH levels in the hippocampus of rats. Ozone significantly inhibited autophagy by decreasing Beclin1 and LC3B expression and increasing p62 expression. The ozone inactivated the NF-κB signaling pathway by decreasing the protein levels of TLR4, p-IKKβ, p-IKBα, and p-p65. We conclude that ozone treatment alleviates the brain injury in ischemic rats by suppressing autophagy and inactivating the NF-κB signaling pathway.

Glial immune-related pathways mediate effects of closed head traumatic brain injury on behavior and lethality in Drosophila

In traumatic brain injury (TBI), the initial injury phase is followed by a secondary phase that contributes to neurodegeneration, yet the mechanisms leading to neuropathology in vivo remain to be elucidated. To address this question, we developed a Drosophila head-specific model for TBI termed Drosophila Closed Head Injury (dCHI), where well-controlled, nonpenetrating strikes are delivered to the head of unanesthetized flies. This assay recapitulates many TBI phenotypes, including increased mortality, impaired motor control, fragmented sleep, and increased neuronal cell death. TBI results in significant changes in the transcriptome, including up-regulation of genes encoding antimicrobial peptides (AMPs). To test the in vivo functional role of these changes, we examined TBI-dependent behavior and lethality in mutants of the master immune regulator NF-κB, important for AMP induction, and found that while sleep and motor function effects were reduced, lethality effects were enhanced. Similarly, loss of most AMP classes also renders flies susceptible to lethal TBI effects. These studies validate a new Drosophila TBI model and identify immune pathways as in vivo mediators of TBI effects.

Traumatic brain injury in Drosophila causes sleep and motor impairments, as well as a strong activation of the innate immune response that is crucial for survival. This study leverages Drosophila as a model organism to reveal neuroprotective and neurotoxic injury mechanisms more quickly using high throughout approaches.

Neuroprotective Effect of Plasminogen Activator Inhibitor-1 Antagonist in the Rat Model of Mild Traumatic Brain Injury

Plasminogen activator inhibitor-1 (PAI-1) antagonists are known for their neuroprotective effects. In this study, it was aimed to investigate the possible protective effects of PAI-1 antagonists in a rat mild traumatic brain injury (TBI) model. Sprague-Dawley male rats were grouped as sham (n = 7), TBI (n = 9), and TBI + PAI-1 antagonist (5 and 10 mg/kg TM5441 and TM5484; n = 6-7). Under anesthesia, TBI was induced by dropping a metal 300-g weight from a height of 1 m on the skull. Before and 24-h after trauma neurological examination, tail suspension, Y-maze, and novel object recognition tests were performed. Twenty-four hours after TBI, the rats were decapitated and activities of myeloperoxidase, nitric oxide release, luminol-, and lucigenin-enhanced chemiluminescence were measured. Also, interleukin-1β, interleukin-6, tumor necrosis factor, interleukin-10, tumor growth factor-β, caspase-3, cleaved caspase-3, and PAI levels were measured with the ELISA method in the brain tissue. Brain injury was graded histopathologically following hematoxylin-eosin staining. Western blot and immunohistochemical investigation for low-density lipoprotein receptor, matrix metalloproteinase-3, and nuclear factor-κB were also performed. Data were analyzed using GraphPad Prism 8.0 (GraphPad Software, San Diego, CA, USA) and expressed as means ± SEM. Values of p < 0.05 were considered to be statistically significant. Higher levels of myeloperoxidase activity in the TBI group (p < 0.05) were found to be suppressed in 5 and 10 mg/kg TM5441 treatment groups (p < 0.05-p < 0.01). The tail suspension test score was increased in the TBI group (p < 0.001) and decreased in all treatment groups (p < 0.05-0.001). The histologic damage score was increased statistically significantly in the cortex, dentate gyrus, and CA3 regions in the TBI group (p < 0.01-0.001), decreased in the treatment groups in the cortex and dentate gyrus (p < 0.05-0.001). PAI antagonists, especially TM5441, have antioxidant and anti-inflammatory properties against mild TBI in the acute period. Behavioral test results were also improved after PAI antagonist treatment after mild TBI.

Inflammatory Molecules Released by Mechanically Injured Astrocytes Trigger Presynaptic Loss in Cortical Neuronal Networks

Deformation, compression, or stretching of brain tissues cause diffuse axonal injury (DAI) and induce structural and functional alterations of astrocytes, the most abundant cell type in the brain. To gain further insight into the role of mechanically activated astrocytes on neuronal networks, this study was designed to investigate whether cytokines released by mechanically activated astrocytes can affect the growth and synaptic connections of cortical neuronal networks. Astrocytes were cultivated on elastic membranes and subjected to repetitive mechanical insults, whereas well-defined protein micropatterns were used to form standardized neuronal networks. GFAP staining showed that astrocytes were mechanically activated after two cycles of stretch and mesoscale discovery assays indicated that injured astrocytes released four major cytokines. To understand the role of these cytokines, neuronal networks were cultured with the supernatant of healthy or mechanically activated astrocytes, and the individual contribution of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) was studied. We found that the supernatant of two-cycle stretched astrocytes decreased presynaptic terminals and indicated that TNF-α must be considered a key player of the synaptic loss. Furthermore, our results indicate that cytokines released by injured astrocytes significantly modulate the balance between TNFR1 and TNFR2 receptors by enhancing R2 receptors. We demonstrated that TNF-α is not involved in this process, suggesting a predominant role of other secreted cytokines. Together, these results contribute to a better understanding of the consequences of repetitive astrocyte deformations and highlight the role of inflammatory signaling pathways in synaptic plasticity and modulation of TNFR1 and TNFR2 receptors.

Impact of chronic smoking on traumatic brain microvascular injury: An in vitro study

Traumatic brain injury (TBI) is a major reason of cerebrovascular and neurological damage. Premorbid conditions such as tobacco smoking (TS) can worsen post‐TBI injuries by promoting vascular endothelial impairments. Indeed, TS‐induced oxidative stress (OS) and inflammation can hamper the blood‐brain barrier (BBB) endothelium. This study evaluated the subsequence of chronic TS exposure on BBB endothelial cells in an established in vitro model of traumatic cell injury. Experiments were conducted on confluent TS‐exposed mouse brain microvascular endothelial cells (mBMEC‐P5) following scratch injury. The expression of BBB integrity–associated tight junction (TJ) proteins was assessed by immunofluorescence imaging (IF), Western blotting (WB) and quantitative RT‐PCR. We evaluated reactive oxygen species (ROS) generation, the nuclear factor 2–related (Nrf2) with its downstream effectors and several inflammatory markers. Thrombomodulin expression was used to assess the endothelial haemostatic response to injury and TS exposure. Our results show that TS significantly decreased Nrf2, thrombomodulin and TJ expression in the BBB endothelium injury models while increased OS and inflammation compared to parallel TS‐free cultures. These data suggest that chronic TS exposure exacerbates traumatic endothelial injury and abrogates the protective antioxidative cell responses. The downstream effect was a more significant decline of BBB endothelial viability, which could aggravate subsequent neurological impairments.

PTEN nuclear translocation enhances neuronal injury after hypoxia-ischemia via modulation of the nuclear factor-κB signaling pathway

The occurrence of hypoxia-ischemia (HI) in the developing brain is closely associated with neuronal injury and even death. However, the underlying molecular mechanism is not fully understood. This study was designed to investigate phosphatase and tensin homolog (PTEN) nuclear translocation and its possible role in rat cortical neuronal damage following oxygen-glucose deprivation (OGD) in vitro. An in vitro OGD model was established using primary cortical neurons dissected from newborn Sprague-Dawley rats to mimic HI conditions. The PTENK13R mutant plasmid, which contains a lysine-to-arginine mutation at the lysine 13 residue, was constructed. The nuclei and cytoplasm of neurons were separated. Neuronal injury following OGD was evidenced by increased lactate dehydrogenase (LDH) release and apoptotic cell counts. In addition, PTEN expression was increased and the phosphorylation of extracellular signal-regulated kinase 1/2 (p-ERK1/2) and activation of nuclear factor kappa B (NF-κB) were decreased following OGD. PTENK13R transfection prevented PTEN nuclear translocation; attenuated the effect of OGD on nuclear p-ERK1/2 and NF-κB, apoptosis, and LDH release; and increased the expression of several anti-apoptotic proteins. We conclude that PTEN nuclear translocation plays an essential role in neuronal injury following OGD via modulation of the p-ERK1/2 and NF-κB pathways. Prevention of PTEN nuclear translocation might be a candidate strategy for preventing brain injury following HI.

Challenges with Methods for Detecting and Studying the Transcription Factor Nuclear Factor Kappa B (NF-κB) in the Central Nervous System

The transcription factor nuclear factor kappa B (NF-κB) is highly expressed in almost all types of cells. NF-κB is involved in many complex biological processes, in particular in immunity. The activation of the NF-κB signaling pathways is also associated with cancer, diabetes, neurological disorders and even memory. Hence, NF-κB is a central factor for understanding not only fundamental biological presence but also pathogenesis, and has been the subject of intense study in these contexts. Under healthy physiological conditions, the NF-κB pathway promotes synapse growth and synaptic plasticity in neurons, while in glia, NF-κB signaling can promote pro-inflammatory responses to injury. In addition, NF-κB promotes the maintenance and maturation of B cells regulating gene expression in a majority of diverse signaling pathways. Given this, the protein plays a predominant role in activating the mammalian immune system, where NF-κB-regulated gene expression targets processes of inflammation and host defense. Thus, an understanding of the methodological issues around its detection for localization, quantification, and mechanistic insights should have a broad interest across the molecular neuroscience community. In this review, we summarize the available methods for the proper detection and analysis of NF-κB among various brain tissues, cell types, and subcellular compartments, using both qualitative and quantitative methods. We also summarize the flexibility and performance of these experimental methods for the detection of the protein, accurate quantification in different samples, and the experimental challenges in this regard, as well as suggestions to overcome common challenges.

The Role of NF-κB Triggered Inflammation in Cerebral Ischemia

Cerebral ischemia is a devastating disease that affects many people worldwide every year. The neurodegenerative damage as a consequence of oxygen and energy deprivation, to date, has no known effective treatment. The ischemic insult is followed by an inflammatory response that involves a complex interaction between inflammatory cells and molecules which play a role in the progression towards cell death. However, there is presently a matter of controversy over whether inflammation could either be involved in brain damage or be a necessary part of brain repair. The inflammatory response is triggered by inflammasomes, key multiprotein complexes that promote secretion of pro-inflammatory cytokines. An early event in post-ischemic brain tissue is the release of certain molecules and reactive oxygen species (ROS) from injured neurons which induce the expression of the nuclear factor-kappaB (NF-κB), a transcription factor involved in the activation of the inflammasome. There are conflicting observations related to the role of NF-κB. While some observe that NF-κB plays a damaging role, others suggest it to be neuroprotective in the context of cerebral ischemia, indicating the need for additional investigation. Here we discuss the dual role of the major inflammatory signaling pathways and provide a review of the latest research aiming to clarify the relationship between NF-κB mediated inflammation and neuronal death in cerebral ischemia.

Role of innate inflammation in traumatic brain injury

Traumatic brain injury is one of the leading causes of morbidity and mortality throughout the world. Its increasing incidence, in addition to its fundamental role in the development of neurodegenerative disease, proves especially concerning. Despite extensive preclinical and clinical studies, researchers have yet to identify a safe and effective neuroprotective strategy. Following brain trauma, secondary injury from molecular, metabolic, and cellular changes causes progressive cerebral tissue damage. Chronic neuroinflammation following traumatic brain injuries is a key player in the development of secondary injury. Targeting this phenomenon for development of effective neuroprotective therapies holds promise. This strategy warrants a concrete understanding of complex neuroinflammatory mechanisms. In this review, we discuss pathophysiological mechanisms such as the innate immune response, glial activation, blood-brain barrier disruption, activation of immune mediators, as well as biological markers of traumatic brain injury. We then review existing and emerging pharmacological therapies that target neuroinflammation to improve functional outcome.

High Expression of Lysophosphatidic Acid Induces Nerve Injury in LSS Patients via AKT Mediated NF-κB p65 Pathway

Lumbar spinal stenosis (LSS) is a spinal degenerative disease, complicated with nerve injury. Lysophosphatidic acid (LPA), a kind of glycerophospholipid molecule is elevated in the initial stages of neural injury. This research aimed to investigate the patho-mechanism of nerve injury caused by LPA in LSS patients. Twenty-five LSS patients and fifteen idiopathic scoliosis patients (without neurological symptoms) were recruited from Xianyang Central Hospital of Shanxi Province. We measured the concentration of LPA in cerebrospinal fluid samples of all subjects. Different concentrations (0.1, 1, and 10 mol/L) of LPA were used to stimulate Rat Neurons-spinal cord (RN-SC) cells. The effects of LPA on cell injury was detected by MTT and LDH (lactate dehydrogenase) assay. Cell apoptosis was determined by FCM (flow cytometry) and TUNEL staining. The changes in the expression of key proteins involved in Akt mediated NF-κB p65 pathway intervened by LPA were determined by western blot. RN-SC cells were pretreated with JSH-23 (NF-κB inhibitor) before LPA exposure, followed by cell apoptosis measurement. The concentration of LPA in LSS patients was notably higher than that in control patients (p < 0.01). The level of LPA was positively correlated with the severity of LSS. LPA treatment induced RN-SC cells displaying oval or rounded cell body with degenerated protrusion dose dependently. In addition, LPA decreased RN-SC cell viability and promoted cell apoptosis in a dose-dependent manner. LPA initiated Akt phosphorylation, IKB phosphorylation, and NF-κB nuclear translocation in a dose-dependent manner. However, JSH-23 (NF-κB inhibitor) pre-treatment prevented effects of LPA. The high levels of LPA induced nerve injury by reducing the viability of RN-SC cells and promoted cell apoptosis through Akt mediated NF-κB p65 signaling pathway. LPA might be a new therapeutic target for relieving nerve injury in LSS patients.

iTRAQ-based proteomic profiling reveals protein alterations after traumatic brain injury and supports thyroxine as a potential treatment

Traumatic brain injury (TBI) is a primary cause of disability and death across the world. Previously, RNA analysis was widely used to study the pathophysiological mechanisms underlying TBI; however, the relatively low correlation between the transcriptome and proteome revealed that RNA transcription abundance does not reliably predict protein abundance, which led to the emergence of proteomic research. In this study, an iTRAQ proteomics approach was applied to detect protein alterations after TBI on a large scale. A total of 3937 proteins were identified, and 146 proteins were significantly changed after TBI. Moreover, 23 upregulated proteins were verified by parallel reaction monitoring (PRM), and fold changes in 16 proteins were consistent with iTRAQ outcomes. Transthyretin (Ttr) upregulation has been demonstrated at the transcriptional level, and this study further confirmed this at the protein level. After treatment with thyroxine (T4), which is transported by Ttr, the effects of T4 on neuronal histopathology and behavioral performance were determined in vivo (TBI + T4 group). Brain edema was alleviated, and the integrity of the blood brain barrier (BBB) improved. Escape latency in the Morris water maze (MWM) declined significantly compared with the group without T4 treatment. Modified neurological severity scores (mNSS) of the TBI + T4 group decreased from day 1 to day 7 post-TBI compared with the TBI + saline group. These results indicate that T4 treatment has potential to alleviate pathologic and behavioral abnormalities post-TBI. Protein alterations after T4 treatment were also detected by iTRAQ proteomics. Upregulation of proteins like Lgals3, Gfap and Apoe after TBI were reversed by T4 treatment. GO enrichment showed T4 mainly affected intermediate filament organization, cholesterol transportation and axonal regeneration. In summary, iTRAQ proteomics provides information about the impact of TBI on protein alterations and yields insight into underlying mechanisms and pathways involved in TBI and T4 treatment. Finally, Ttr and other proteins identified by iTRAQ may become potential novel treatment targets post-TBI.

Survival Following Traumatic Brain Injury in Drosophila Is Increased by Heterozygosity for a Mutation of the NF-κB Innate Immune Response Transcription Factor Relish

Traumatic brain injury (TBI) pathologies are caused by primary and secondary injuries. Primary injuries result from physical damage to the brain, and secondary injuries arise from cellular responses to primary injuries. A characteristic cellular response is sustained activation of inflammatory pathways commonly mediated by nuclear factor-κB (NF-κB) transcription factors. Using a Drosophila melanogaster TBI model, we previously found that the main proximal transcriptional response to primary injuries is triggered by activation of Toll and Imd innate immune response pathways that engage NF-κB factors Dif and Relish (Rel), respectively. Here, we found by mass spectrometry that Rel protein level increased in fly heads at 4-8 hr after TBI. To investigate the necessity of Rel for secondary injuries, we generated a null allele, Reldel , by CRISPR/Cas9 editing. When heterozygous but not homozygous, the Reldel mutation reduced mortality at 24 hr after TBI and increased the lifespan of injured flies. Additionally, the effect of heterozygosity for Reldel on mortality was modulated by genetic background and diet. To identify genes that facilitate effects of Reldel on TBI outcomes, we compared genome-wide mRNA expression profiles of uninjured and injured +/+, +/Reldel , and Reldel /Reldel flies at 4 hr following TBI. Only a few genes changed expression more than twofold in +/Reldel flies relative to +/+ and Reldel /Reldel flies, and they were not canonical innate immune response genes. Therefore, Rel is necessary for TBI-induced secondary injuries but in complex ways involving Rel gene dose, genetic background, diet, and possibly small changes in expression of innate immune response genes.

Neuroprotective Effect of Oridonin on Traumatic Brain Injury via Inhibiting NLRP3 Inflammasome in Experimental Mice

NLRP3 inflammasome has been considered as an important contributor to inflammation and neuronal death after traumatic brain injury (TBI). Oridonin (Ori), the major active ingredient of Chinese herbal medicine Rabdosia rubescens, has been proved to be a covalent NLRP3 inhibitor with strong anti-inflammation activity. The purpose of this study was to investigate the effect of Ori on inflammation and brain injury induced by TBI. Adult male C57BL/6 mice were subjected to closed-head injury using Hall's weight-dropping method. Ori was injected directly intraperitoneally at a dose of 10 mg/kg within 30 min after TBI and injected once daily until the experiments ended. Our results showed that NLRP3 inflammasome was activated within 24 h post-TBI. The expression of NLRP3 inflammasome components (NLRP3, ASC, and caspase-1) was significantly decreased after treatment with Ori. Besides, the secretion of IL-1β and IL-18, downstream inflammatory factors of activated caspase-1, was reduced by Ori treatment. Importantly, Ori administration further protected the blood-brain barrier, alleviated brain edema, reduced cortical lesion volume, decreased cell death, and attenuated neurological deficits after TBI. Our findings indicate that NLRP3 inflammasome participated in the secondary injury after TBI and the application of Ori may provide neuroprotection via inhibiting NLRP3 inflammasome in animal models, suggesting that Ori might be a promising candidate for patients with TBI.

Adenosine A3 receptor as a novel therapeutic target to reduce secondary events and improve neurocognitive functions following traumatic brain injury

Background

Traumatic brain injury (TBI) is a common pathological condition that presently lacks a specific pharmacological treatment. Adenosine levels rise following TBI, which is thought to be neuroprotective against secondary brain injury. Evidence from stroke and inflammatory disease models suggests that adenosine signaling through the G protein-coupled A₃ adenosine receptor (A₃AR) can provide antiinflammatory and neuroprotective effects. However, the role of A₃AR in TBI has not been investigated.

Methods

Using the selective A₃AR agonist, MRS5980, we evaluated the effects of A₃AR activation on the pathological outcomes and cognitive function in CD1 male mouse models of TBI.

Results

When measured 24 h after controlled cortical impact (CCI) TBI, male mice treated with intraperitoneal injections of MRS5980 (1 mg/kg) had reduced secondary tissue injury and brain infarction than vehicle-treated mice with TBI. These effects were associated with attenuated neuroinflammation marked by reduced activation of nuclear factor of kappa light polypeptide gene enhancer in B cells (NFκB) and MAPK (p38 and extracellular signal-regulated kinase (ERK)) pathways and downstream NOD-like receptor pyrin domain-containing 3 inflammasome activation. MRS5980 also attenuated TBI-induced CD4⁺ and CD8⁺ T cell influx. Moreover, when measured 4–5 weeks after closed head weight-drop TBI, male mice treated with MRS5980 (1 mg/kg) performed significantly better in novel object-placement retention tests (NOPRT) and T maze trials than untreated mice with TBI without altered locomotor activity or increased anxiety.

Conclusion

Our results provide support for the beneficial effects of small molecule A₃AR agonists to mitigate secondary tissue injury and cognitive impairment following TBI.

TMT-based proteomics analysis to screen potential biomarkers of acute-phase TBI in rats

AIMS

Traumatic brain injury (TBI) is a common nervous system injury. However, the detailed mechanisms about functional dysregulation and dignostic biomarkers post-TBI are still unclear. So we aimed to identify potential differentially expressed proteins and genes in TBI for clinical diagnosis and therapeutic purposes.

MAIN METHODS

Rat TBI model was established by the weight-drop method. First, through TMT-proteomics, we screened for the change in the proteins expression profile acute phase post-TBI. The DAVID and Reactome databases were used to analyze and visualize the dysregulation proteins. Then, using publicly available microarray datasets GSE45997, differentially expressed genes (DGEs) were identified for the 24 h post-TBI stage. Also, the proteomic data were compared with microarray data to analyze the similarity.

KEY FINDINGS

We found significant proteomics and transcriptomic changes in post-TBI samples. 989, 881, 832, 1057 proteins were quantitated at 1 h, 6 h, 24 h, and 3 d post-injury correspondingly. Concerning proteomics findings, oxygen transport, acute-phase response, and negative regulation of endopeptidase activity were influenced throughout the acute phrase of TBI. Also, pathways related to scavenging of heme from plasma, binding, and uptake of ligands by scavenger receptors were highly enriched in all time-points of TBI samples.

SIGNIFICANCE

We noticed that the interaction-networks trend to get complicated with more node connections following the progression of TBI. We inferred that Hk-1, PRKAR2A, and MBP could be novel candidate biomarkers related to time-injury in acute-phase TBI. Also, Ceruloplasmin and Complement C3 were found to be important proteins and genes are involved in the TBI.

Effects of electroconvulsive shock on neuro-immune responses: Does neuro-damage occur?

Electroconvulsive therapy (ECT) is one of the most effective treatments for treatment-resistant depression. However, this treatment may produce memory impairment. The mechanisms of the cognitive adverse effects are not known. Neuroimmune response is related to the cognitive deficits. By reviewing the available animal literature, we examined the glia activation, inflammatory cytokines, neuron oxidative stress responses, and neural morphological changes following electroconvulsive shock (ECS) treatment. The studies showed that ECS activates microglia, upregulates neuro-inflammatory cytokines, and increases oxidative stress responses. But these effects are rapid and may be transient. They normalize as ECS treatment continues, suggesting endogenous neuroprotection may be mobilized. The transient changes are well in line with the clinical observations that ECT usually does not cause significant long-lasting retrograde amnesia. The longitudinal studies will be particularly important to explore the dynamic changes of neuroplasticity following ECT (Jonckheere et al., 2018). Investigating the neuroplasticity changes in animals that suffered chronic stress may also be crucial to giving support to the translation of preclinical research.

IKKγ/NEMO Is Required to Confer Antimicrobial Innate Immune Responses in the Yellow Mealworm, Tenebrio Molitor

IKKγ/NEMO is the regulatory subunit of the IκB kinase (IKK) complex, which regulates the NF-κB signaling pathway. Within the IKK complex, IKKγ/NEMO is the non-catalytic subunit, whereas IKKα and IKKβ are the structurally related catalytic subunits. In this study, TmIKKγ was screened from the Tenebrio molitor RNA-Seq database and functionally characterized using RNAi screening for its role in regulating T. molitor antimicrobial peptide (AMP) genes after microbial challenges. The TmIKKγ transcript is 1521 bp that putatively encodes a polypeptide of 506 amino acid residues. TmIKKγ contains a NF-κB essential modulator (NEMO) and a leucine zipper domain of coiled coil region 2 (LZCC2). A phylogenetic analysis confirmed its homology to the red flour beetle, Tribolium castaneum IKKγ (TcIKKγ). The expression of TmIKKγ mRNA showed that it might function in diverse tissues of the insect, with a higher expression in the hemocytes and the fat body of the late-instar larvae. TmIKKγ mRNA expression was induced by Escherichia coli, Staphylococcus aureus, and Candida albicans challenges in the whole larvae and in tissues such as the hemocytes, gut and fat body. The knockdown of TmIKKγ mRNA significantly reduced the survival of the larvae after microbial challenges. Furthermore, we investigated the tissue-specific induction patterns of fourteen T. molitor AMP genes in TmIKKγ mRNA-silenced individuals after microbial challenges. In general, the mRNA expression of TmTenecin1, -2, and -4; TmDefensin1 and -2; TmColeoptericin1 and 2; and TmAttacin1a, 1b, and 2 were found to be downregulated in the hemocytes, gut, and fat body tissues in the TmIKKγ-silenced individuals after microbial challenges. Under similar conditions, TmRelish (NF-κB transcription factor) mRNA was also found to be downregulated. Thus, TmIKKγ is an important factor in the antimicrobial innate immune response of T. molitor.

ALS-associated TBK1 variant p.G175S is defective in phosphorylation of p62 and impacts TBK1-mediated signalling and TDP-43 autophagic degradation

Mutations affecting SQSTM1 coding for p62 and TANK-Binding Kinase 1 (TBK1) have been implicated in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). TBK1 is a serine-threonine kinase that regulates p62's activity as an autophagy receptor via phosphorylation and also has roles in neuroinflammatory signalling pathways. The mechanisms underlying ALS and FTLD pathogenesis as a result of TBK1 mutations are incompletely understood, however, loss of TBK1 function can lead to dysregulated autophagy and mitophagy. Here, we report that an ALS-associated TBK1 variant affecting the kinase domain, p.G175S, is defective in phosphorylation of p62 at Ser-403, a modification critical for regulating its ubiquitin-binding function, as well as downstream phosphorylation at Ser-349. Consistent with these findings, expression of p.G175S TBK1 was associated with decreased induction of autophagy compared to wild type and reduced degradation of the ALS-linked protein TDP-43. Expression of wild type TBK1 increased NF-κB signalling ~300 fold in comparison to empty vector cells, whereas p.G175S TBK1 was unable to promote NF-κB signalling above levels observed in empty vector transfected cells. We also noted a hitherto unknown role for TBK1 as a suppressor of oxidative stress (Nrf2) signalling and show that p.G175S TBK1 expressing cells lose this inhibitory function. Our data suggest that TBK1 ALS mutations may broadly impair p62-mediated cell signalling, which ultimately may reduce neuronal survival, in addition TDP-43 was not efficiently degraded, together these effects may contribute to TBK1 mutation associated ALS and FTLD pathogenesis.

Fibrinogen and Neuroinflammation During Traumatic Brain Injury

Many neurodegenerative diseases such as Alzheimer's disease (AD), multiple sclerosis, and traumatic brain injury (TBI) are associated with systemic inflammation. Inflammation itself results in increased blood content of fibrinogen (Fg), called hyperfibrinogenemia (HFg). Fg is not only considered an acute phase protein and a marker of inflammation, but has been shown that it can cause inflammatory responses. Fibrin deposits have been associated with memory reduction in neuroinflammatory diseases such as AD and TBI. Reduction in short-term memory has been seen during the most common form of TBI, mild-to-moderate TBI. Fibrin deposits have been found in brains of patients with mild-to-moderate TBI. The vast majority of the literature emphasizes the role of fibrin-activated microglia as the mediator in the neuroinflammation pathway. However, the recent discovery that astrocytes, which constitute approximately 30% of the cells in the mammalian central nervous system, manifest different reactive states warrants further investigations in the causative role of HFg in astrocyte-mediated neuroinflammation. Our previous study showed that Fg deposited in the vasculo-astrocyte interface-activated astrocytes. However, little is known of how Fg directly affects astrocytes and neurons. In this review, we summarize studies that show the effect of Fg on different types of cells in the vasculo-neuronal unit. We will also discuss the possible mechanism of HFg-induced neuroinflammation during TBI.

Absence of Glia Maturation Factor Protects from Axonal Injury and Motor Behavioral Impairments after Traumatic Brain Injury

Traumatic brain injury (TBI) causes disability and death, accelerating the progression towards Alzheimer's disease and Parkinson's disease (PD). TBI causes serious motor and cognitive impairments, as seen in PD that arise during the period of the initial insult. However, this has been understudied relative to TBI induced neuroinflammation, motor and cognitive decline that progress towards PD. Neuronal ubiquitin-C-terminal hydrolase- L1 (UCHL1) is a thiol protease that breaks down ubiquitinated proteins and its level represents the severity of TBI. Previously, we demonstrated the molecular action of glia maturation factor (GMF); a proinflammatory protein in mediating neuroinflammation and neuronal loss. Here, we show that the weight drop method induced TBI neuropathology using behavioral tests, western blotting, and immunofluorescence techniques on sections from wild type (WT) and GMF-deficient (GMF-KO) mice. Results reveal a significant improvement in substantia nigral tyrosine hydroxylase and dopamine transporter expression with motor behavioral performance in GMF-KO mice following TBI. In addition, a significant reduction in neuroinflammation was manifested, as shown by activation of nuclear factor-kB, reduced levels of inducible nitric oxide synthase, and cyclooxygenase- 2 expressions. Likewise, neurotrophins including brain-derived neurotrophic factor and glial-derived neurotrophic factor were significantly improved in GMF-KO mice than WT 72 h post-TBI. Consistently, we found that TBI enhances GFAP and UCHL-1 expression and reduces the number of dopaminergic TH-positive neurons in WT compared to GMF-KO mice 72 h post-TBI. Interestingly, we observed a reduction of THpositive tanycytes in the median eminence of WT than GMF-KO mice. Overall, we found that absence of GMF significantly reversed these neuropathological events and improved behavioral outcome. This study provides evidence that PD-associated pathology progression can be initiated upon induction of TBI.

Neuroinflammatory Responses and Parkinson' Disease: Pathogenic Mechanisms and Therapeutic Targets

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorders of the central nervous system, which mainly impairs the motor system. However, the pathogenic mechanisms are still unclear. Gene-environment complex interaction leads to selective dopaminergic neuron death in PD. Growing evidences supports that neuroinflammatory responses are involved in the pathogenesis of PD. This review critically discusses current studies on the inflammatory response of the pathological process of PD. The mechanisms and strategies of modifying inflammatory responses would be potential treatments for neurodegenerative diseases. Graphical abstract Activated microglia canpromote the damage ofdopaminergic neurons, which inturn aggravates the activation ofmicroglia in the process of PD. Atthe same time, microglia canactivate astrocytes throughproliferation and secretion ofinflammatory factors. The role ofastrocytes on the loss ofdopaminergic neurons is stillcontroversial in PD. (Nonsteroidalanti-inflammatory drugs,NSAIDs. adiposed-derived stemcells, ADSCs.nicotinamideadenine dinucleotide phosphate,NADPH. signal transducers andactivators of transcription,STAT.DJ-1,Aliases forPARK7.mesencephalic astrocytederivedneurotrophic factor,MANF.Ciliary neurotrophicfactor,CNTF.glial cell linederivedneurotrophic factor,GDNF.Wnt Family Member1,Wnt1). Graphical abstract Mitochondrial dysfunction causes neuroinflammation throughDAMPs and a series of factors such as oxidative stress andinflammatory bodies in PD. (Damage-associated molecular patterns,DAMPs. reactive oxygen species, ROS). Graphical abstract Various mechanismsparticipate in NLRP3 activation,causing microglia activation inPD. ( -synuclein, -syn.) TolllikeReceptor 2, TLR2. Toll-likeReceptor 4, TLR4. TumorNecrosis Factor, TNF.Apoptosisassociated speck like proteincontaining a CARD, ASC).

Mesenchymal stem cell therapy for the treatment of traumatic brain injury: progress and prospects

Traumatic brain injury (TBI) is a major cause of injury-related mortality and morbidity in the USA and around the world. The survivors may suffer from cognitive and memory deficits, vision and hearing loss, movement disorders, and different psychological problems. The primary insult causes neuronal damage and activates astrocytes and microglia which evokes immune responses causing further damage to the brain. Clinical trials of drugs to recover the neuronal loss are not very successful. Regenerative approaches for TBI using mesenchymal stem cells (MSCs) seem promising. Results of preclinical research have shown that transplantation of MSCs reduced secondary neurodegeneration and neuroinflammation, promoted neurogenesis and angiogenesis, and improved functional outcome in the experimental animals. The functional improvement is not necessarily related to cell engraftment; rather, immunomodulation by molecular factors secreted by MSCs is responsible for the beneficial effects of this therapy. However, MSC therapy has a few drawbacks including tumor formation, which can be avoided by the use of MSC-derived exosomes. This review has focused on the research works published in the field of regenerative therapy using MSCs after TBI and its future direction.

Ferroptosis-relevant mechanisms and biomarkers for therapeutic interventions in traumatic brain injury

Traumatic brain injury (TBI) is one of the most significant health care problems worldwide, causing disability and death especially among young individuals. Although a large range of agents and therapies have been proved beneficial to lesions post-TBI to some extent, effective treatments have not been translated to the clinic. As a newly discovered form of iron-dependent regulated cell death, ferroptosis has been implicated in TBI. In this review, we update the current state of knowledge related to second injuries post-TBI, including ferroptosis, oxidative stress, mitochondrial dysfunction, neuroinflammation and so on, which often lead to chronic symptoms and long-term disability. This review systematically summarizes the latest progress in the pathophysiological mechanisms of TBI, with a focus on providing references for proposing new multi-molecular targets for comprehensive therapeutic strategies based on ferroptosis-relevant mechanisms. In addition, biomarkers are essential diagnostic and prognostic tools in TBI. Several biomarkers associated with the outcome of TBI have been listed in this article, such as Pde10a, MDA, UCH-L1, S100A9, S100B, ALDOC, ACSL4, MBP and F2-Isoprostane. Therefore, the understating of ferroptosis-relevant mechanisms and biomarkers may contribute to development of promising therapies for TBI clinical trials.

The cerebrovascular and neurological impact of chronic smoking on post-traumatic brain injury outcome and recovery: an in vivo study

BACKGROUND

Traumatic brain injury (TBI) is among the most prevalent causes of cerebrovascular and neurological damage worldwide. To this end, tobacco smoke (TS) has been shown to promote vascular inflammation, neurovascular impairments, and risk of cerebrovascular and neurological disorders through oxidative stress (OS) stimuli targeting the blood-brain barrier (BBB) endothelium among others. It has been recently suggested that premorbid conditions such as TS may exacerbate post-TBI brain damage and impact recovery.

METHODS

Our study investigated the mechanisms underlying the exacerbation of TBI injury by TS using a weight drop model. For this purpose, male C57BL/6J mice, age range 6-8 weeks, were chronically exposed to premorbid TS for 3 weeks. Test animals were then subjected to TBI by guided vertical head weight drop using a 30 g metal weight free felling from an 80 cm distance before reaching the target. We analyzed the physical activity and body weight of the mice before TBI and 1 h, 24 h, and 72 h post-injury. Finally, mice were sacrificed to collect blood and brain samples for subsequent biochemical and molecular analysis. Western blotting was applied to assess the expression of Nrf2 (a critical antioxidant transcription factor) as well as tight junction proteins associated with BBB integrity including ZO-1, Occludin, and Claudin-5 from brain tissues homogenates. Levels of NF-kB (a pro-inflammatory transcript factor which antagonizes Nrf2 activity) and pro-inflammatory cytokines IL-6, IL-10, and TNF-α were assessed in blood samples.

RESULTS

Our data revealed that premorbid TS promoted significantly increased inflammation and loss of BBB integrity in TBI when compared to TS-Free test mice. Additionally, mice chronically exposed to TS before TBI experienced a more significant weight loss, behavioral and motor activity deficiency, and slower post-TBI recovery when compared to TS-free TBI mice.

CONCLUSION

The effects of premorbid TS appear consequential to the abrogation of physiological antioxidative and anti-inflammatory response to TBI leading to worsening impairments of the BBB, OS damage, and inflammation. These factors are also likely responsible for the retardation of post-traumatic recovery observed in these animals.

Traumatic Brain Injury and Blood-Brain Barrier (BBB): Underlying Pathophysiological Mechanisms and the Influence of Cigarette Smoking as a Premorbid Condition

Traumatic brain injury (TBI) is among the most pressing global health issues and prevalent causes of cerebrovascular and neurological disorders all over the world. In addition to the brain injury, TBI may also alter the systemic immune response. Thus, TBI patients become vulnerable to infections, have worse neurological outcomes, and exhibit a higher rate of mortality and morbidity. It is well established that brain injury leads to impairments of the blood-brain barrier (BBB) integrity and function, contributing to the loss of neural tissue and affecting the response to neuroprotective drugs. Thus, stabilization/protection of the BBB after TBI could be a promising strategy to limit neuronal inflammation, secondary brain damage, and acute neurodegeneration. Herein, we present a review highlighting the significant post-traumatic effects of TBI on the cerebrovascular system. These include the loss of BBB integrity and selective permeability, impact on BBB transport mechanisms, post-traumatic cerebral edema formation, and significant pathophysiological factors that may further exacerbate post-traumatic BBB dysfunctions. Furthermore, we discuss the post-traumatic impacts of chronic smoking, which has been recently shown to act as a premorbid condition that impairs post-TBI recovery. Indeed, understanding the underlying molecular mechanisms associated with TBI damage is essential to better understand the pathogenesis and progression of post-traumatic secondary brain injury and the development of targeted treatments to improve outcomes and speed up the recovery process. Therapies aimed at restoring/protecting the BBB may reduce the post-traumatic burden of TBI by minimizing the impairment of brain homeostasis and help to restore an optimal microenvironment to support neuronal repair.

C-terminal binding proteins 1 and 2 in traumatic brain injury-induced inflammation and their inhibition as an approach for anti-inflammatory treatment

Traumatic brain injury (TBI) induces an acute inflammatory response in the central nervous system that involves both resident and peripheral immune cells. The ensuing chronic neuroinflammation causes cell death and tissue damage and may contribute to neurodegeneration. The molecular mechanisms involved in the maintenance of this chronic inflammation state remain underexplored. C-terminal binding protein (CtBP) 1 and 2 are transcriptional coregulators that repress diverse cellular processes. Unexpectedly, we find that the CtBPs can transactivate a common set of proinflammatory genes both in lipopolysaccharide-activated microglia, astrocytes and macrophages, and in a mouse model of the mild form of TBI. We also find that the expression of these genes is markedly enhanced by a single mild injury in both brain and peripheral blood leukocytes in a severity- and time-dependent manner. Moreover, we were able to demonstrate that specific inhibitors of the CtBPs effectively suppress the expression of the CtBP target genes and thus improve neurological outcome in mice receiving single and repeated mild TBIs. This discovery suggests new avenues for therapeutic modulation of the inflammatory response to brain injury.

Interference of neuronal activity-mediated gene expression through serum response factor deletion enhances mortality and hyperactivity after traumatic brain injury

Traumatic brain injury (TBI) is one of the most frequent causes of brain injury and mortality in young adults with detrimental sequelae such as cognitive impairments, epilepsy, and attention-deficit hyperactivity disorder. TBI modulates the neuronal excitability resulting in propagation of a neuronal activity-driven gene expression program. However, the impact of such neuronal activity mediated gene expression in TBI has been poorly studied. In this study we analyzed mouse mutants of the prototypical neuronal activity-dependent transcription factor SRF (serum response factor) in a weight-drop TBI model. Neuron-restricted SRF deletion elevated TBI inflicted mortality suggesting a neuroprotective SRF function during TBI. Behavioral inspection uncovered elevated locomotor activity in Srf mutant mice after TBI in contrast to hypoactivity observed in wild-type littermates. This indicates an SRF role in modulation of TBI-associated alterations in locomotor activity. Finally, induction of a neuronal activity induced gene expression program composed of immediate early genes (IEGs) such as Egr1, Egr2, Egr3, Npas4, Atf3, Arc, Ptgs2, and neuronal pentraxins (Nptx2) was compromised upon SRF depletion. Overall, our data show a role of neuronal activity-mediated gene transcription during TBI and suggest a molecular link between TBI and such post-TBI neurological comorbidities involving hyperactivity phenotypes.