The immune system in neurological diseases: What innate-like T cells have to say

The immune system classically consists of 2 lines of defense, innate and adaptive, both of which interact with one another effectively to protect us against any pathogenic threats. Importantly, there is a diverse subset of cells known as innate-like T cells that act as a bridge between the innate and adaptive immune systems and are pivotal players in eliciting inflammatory immune responses. A growing body of evidence has demonstrated the regulatory impact of these innate-like T cells in central nervous system (CNS) diseases and that such immune cells can traffic into the brain in multiple pathological conditions, which can be typically attributed to the breakdown of the blood-brain barrier. However, until now, it has been poorly understood whether innate-like T cells have direct protective or causative properties, particularly in CNS diseases. Therefore, in this review, our attention is focused on discussing the critical roles of 3 unique subsets of unconventional T cells, namely, natural killer T cells, γδ T cells, and mucosal-associated invariant T cells, in the context of CNS diseases, disorders, and injuries and how the interplay of these immune cells modulates CNS pathology, in an attempt to gain a better understanding of their complex functions.

Oleuropein Has Modulatory Effects on Systemic Lipopolysaccharide-Induced Neuroinflammation in Male Rats

BACKGROUND

Neuroinflammation induced by systemic inflammation is a risk factor for developing chronic neurologic disorders. Oleuropein (OLE) has antioxidant and anti-inflammatory properties; however, its effect on systemic inflammation-related neuroinflammation is unknown.

OBJECTIVES

This study aimed to determine whether OLE protects against systemic lipopolysaccharide (LPS)-induced neuroinflammation in rats.

METHODS

Six-wk-old Wistar rats were randomly assigned to 1 of the following 5 groups: 1) control, 2) OLE-only, 3) LPS + vehicle, 4) OLE+LPS (O-LPS), and 5) a single-dose OLE + LPS (SO-LPS group). OLE 200 mg/kg or saline as a vehicle was administered via gavage for 7 d. On the seventh day, 2.5 mg/kg LPS was intraperitoneally administered. The rats were decapitated after 24 h of LPS treatment, and serum collection and tissue dissection were performed. The study assessed astrocyte and microglial activation using glial fibrillary acidic protein (GFAP) and CD11b immunohistochemistry, nod-like receptor protein-3, interleukin (IL)-1β, IL-17A, and IL-4 concentrations in prefrontal and hippocampal tissues via enzyme-linked immunosorbent assay, and total antioxidant/oxidant status (TAS/TOS) in serum and tissues via spectrophotometry.

RESULTS

In both the O-LPS and SO-LPS groups, LPS-related activation of microglia and astrocytes was suppressed in the cortex and hippocampus (P < 0.001), excluding cortical astrocyte activation, which was suppressed only in the SO-LPS group (P < 0.001). Hippocampal GFAP immunoreactivity and IL-17A concentrations in the dentate gyrus were higher in the OLE group than those in the control group, but LPS-related increases in these concentrations were suppressed in the O-LPS group. The O-LPS group had higher cortical TAS and IL-4 concentrations.

CONCLUSIONS

OLE suppressed LPS-related astrocyte and microglial activation in the hippocampus and cortex. The OLE-induced increase in cortical IL-4 concentrations indicates the induction of an anti-inflammatory phenotype of microglia. OLE may also modulate astrocyte and IL-17A functions, which could explain its opposing effects on hippocampal GFAP immunoreactivity and IL-17A concentrations when administered with or without LPS.

ACOD1, rather than itaconate, facilitates p62-mediated activation of Nrf2 in microglia post spinal cord contusion

BACKGROUND

Spinal cord injury (SCI)-induced neuroinflammation and oxidative stress (OS) are crucial events causing neurological dysfunction. Aconitate decarboxylase 1 (ACOD1) and its metabolite itaconate (Ita) inhibit inflammation and OS by promoting alkylation of Keap1 to induce Nrf2 expression; however, it is unclear whether there is another pathway regulating their effects in inflammation-activated microglia after SCI.

METHODS

Adult male C57BL/6 ACOD1-/- mice and their wild-type (WT) littermates were subjected to a moderate thoracic spinal cord contusion. The degree of neuroinflammation and OS in the injured spinal cord were assessed using qPCR, western blot, flow cytometry, immunofluorescence, and trans-well assay. We then employed immunoprecipitation-western blot, chromatin immunoprecipitation (ChIP)-PCR, dual-luciferase assay, and immunofluorescence-confocal imaging to examine the molecular mechanisms of ACOD1. Finally, the locomotor function was evaluated with the Basso Mouse Scale and footprint assay.

RESULTS

Both in vitro and in vivo, microglia with transcriptional blockage of ACOD1 exhibited more severe levels of neuroinflammation and OS, in which the expression of p62/Keap1/Nrf2 was down-regulated. Furthermore, silencing ACOD1 exacerbated neurological dysfunction in SCI mice. Administration of exogenous Ita or 4-octyl itaconate reduced p62 phosphorylation. Besides, ACOD1 was capable of interacting with phosphorylated p62 to enhance Nrf2 activation, which in turn further promoted transcription of ACOD1.

CONCLUSIONS

Here, we identified an unreported ACOD1-p62-Nrf2-ACOD1 feedback loop exerting anti-inflammatory and anti-OS in inflammatory microglia, and demonstrated the neuroprotective role of ACOD1 after SCI, which was different from that of endogenous and exogenous Ita. The present study extends the functions of ACOD1 and uncovers marked property differences between endogenous and exogenous Ita.

KEY POINTS

ACOD1 attenuated neuroinflammation and oxidative stress after spinal cord injury. ACOD1, not itaconate, interacted with p-p62 to facilitate Nrf2 expression and nuclear translocation. Nrf2 was capable of promoting ACOD1 transcription in microglia.

Microglia measured by TSPO PET are associated with Alzheimer's disease pathology and mediate key steps in a disease progression model

INTRODUCTION

Evidence suggests microglial activation precedes regional tau and neurodegeneration in Alzheimer's disease (AD). We characterized microglia with translocator protein (TSPO) positron emission tomography (PET) within an AD progression model where global amyloid beta (Aβ) precedes local tau and neurodegeneration, resulting in cognitive impairment.

METHODS

Florbetaben, PBR28, and MK-6240 PET, T1 magnetic resonance imaging, and cognitive measures were performed in 19 cognitively unimpaired older adults and 22 patients with mild cognitive impairment or mild AD to examine associations among microglia activation, Aβ, tau, and cognition, adjusting for neurodegeneration. Mediation analyses evaluated the possible role of microglial activation along the AD progression model.

RESULTS

Higher PBR28 uptake was associated with higher Aβ, higher tau, and lower MMSE score, independent of neurodegeneration. PBR28 mediated associations between tau in early and middle Braak stages, between tau and neurodegeneration, and between neurodegeneration and cognition.

DISCUSSION

Microglia are associated with AD pathology and cognition and may mediate relationships between subsequent steps in AD progression.

Botulinum Neurotoxin Induces Neurotoxic Microglia Mediated by Exogenous Inflammatory Responses

Botulinum neurotoxin serotype A (BoNT/A) is widely used in therapeutics and cosmetics. The effects of multi-dosed BoNT/A treatment are well documented on the peripheral nervous system (PNS), but much less is known on the central nervous system (CNS). Here, the mechanism of multi-dosed BoNT/A leading to CNS neurodegeneration is explored by using the 3D human neuron-glia model. BoNT/A treatment reduces acetylcholine, triggers astrocytic transforming growth factor beta, and upregulates C1q, C3, and C5 expression, inducing microglial proinflammation. The disintegration of the neuronal microtubules is escorted by microglial nitric oxide, interleukin 1β, tumor necrosis factor α, and interleukin 8. The microglial proinflammation eventually causes synaptic impairment, phosphorylated tau (pTau) aggregation, and the loss of the BoNT/A-treated neurons. Taking a more holistic approach, the model will allow to assess therapeutics for the CNS neurodegeneration under the prolonged use of BoNT/A.

Modulation of secretory factors by lipofundin contributes to its anti‑neuroinflammatory effects

As the global population ages, the prevalence of neuroinflammatory diseases such as Alzheimer's disease, Parkinson's disease and stroke continues to increase. Therefore, it is necessary to develop preventive and therapeutic methods against neuroinflammatory diseases. Lipofundin is a lipid emulsion commonly used in clinical anesthetic solvents and nutritional supplements. Lipid emulsions have been shown to possess anti-inflammatory properties. However, the potential beneficial effect of lipofundin against neuroinflammation requires elucidation. In the present study, two cell models were used to investigate the efficacy of lipofundin against neuroinflammation. In the first model, BV2 mouse microglial cells were treated with lipopolysaccharide (LPS) to induce nitric oxide (NO) production as a model of neuroinflammation. In the second model, HMC3 human microglial were activated by LPS, and changes in the secretion of factors associated with inflammation were analyzed using Luminex xMAP® technology. Griess assay results revealed that lipofundin significantly prevented and treated LPS-induced NO production. An anti-neuroinflammatory effect was also observed in HMC3 cells, where lipofundin exhibited excellent preventive and therapeutic properties by reducing the LPS-induced expression and secretion of interleukin-1β. Notably, lipofundin also promoted the secretion of certain growth factors, suggesting a potential neuroprotective effect. These results demonstrate that, in addition to its role as a solvent for drugs and nutritional support, lipofundin may also have beneficial effects in alleviating the progression of neuroinflammation. These findings may serve as an important reference for future translational medicine applications.

Regulation of CNS pathology by Serpina3n/SERPINA3: The knowns and the puzzles

Neuroinflammation, blood-brain barrier (BBB) dysfunction, neuron and glia injury/death and myelin damage are common central nervous system (CNS) pathologies observed in various neurological diseases and injuries. Serine protease inhibitor (Serpin) clade A member 3n (Serpina3n), and its human orthologue SERPINA3, is an acute-phase inflammatory glycoprotein secreted primarily by the liver into the bloodstream in response to systemic inflammation. Clinically, SERPINA3 is dysregulated in brain cells, cerebrospinal fluid and plasma in various neurological conditions. Although it has been widely accepted that Serpina3n/SERPINA3 is a reliable biomarker of reactive astrocytes in diseased CNS, recent data have challenged this well-cited concept, suggesting instead that oligodendrocytes and neurons are the primary sources of Serpina3n/SERPINA3. The debate continues regarding whether Serpina3n/SERPINA3 induction represents a pathogenic or a protective mechanism. Here, we propose possible interpretations for previously controversial data and present perspectives regarding the potential role of Serpina3n/SERPINA3 in CNS pathologies, including demyelinating disorders where oligodendrocytes are the primary targets. We hypothesise that the 'good' or 'bad' aspects of Serpina3n/SERPINA3 depend on its cellular sources, its subcellular distribution (or mis-localisation) and/or disease/injury types. Furthermore, circulating Serpina3n/SERPINA3 may cross the BBB to impact CNS pathologies. Cell-specific genetic tools are critically important to tease out the potential roles of cell type-dependent Serpina3n in CNS diseases/injuries.

Correlation between the gut microbiome and neurodegenerative diseases: a review of metagenomics evidence

A growing body of evidence suggests that the gut microbiota contributes to the development of neurodegenerative diseases via the microbiota-gut-brain axis. As a contributing factor, microbiota dysbiosis always occurs in pathological changes of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. High-throughput sequencing technology has helped to reveal that the bidirectional communication between the central nervous system and the enteric nervous system is facilitated by the microbiota's diverse microorganisms, and for both neuroimmune and neuroendocrine systems. Here, we summarize the bioinformatics analysis and wet-biology validation for the gut metagenomics in neurodegenerative diseases, with an emphasis on multi-omics studies and the gut virome. The pathogen-associated signaling biomarkers for identifying brain disorders and potential therapeutic targets are also elucidated. Finally, we discuss the role of diet, prebiotics, probiotics, postbiotics and exercise interventions in remodeling the microbiome and reducing the symptoms of neurodegenerative diseases.

Clinical Relevance of Plasma Prolylcarboxypeptidase Level in Patients with Idiopathic Acute Optic Neuritis

Objectives: This study evaluated the plasma concentration of prolylcarboxypeptidase (PRCP) and its clinical relevance in patients with idiopathic acute optic neuritis (ON). Methods: We investigated the expression of PRCP in the optic nerves of experimental autoimmune optic neuritis (EAON)-induced mice. Peripheral blood samples were collected from ON patients (n = 20) and healthy controls (n = 20). ELISA was used to measure the plasma PRCP levels. We performed measurements of visual acuity and the mean thicknesses of the macular ganglion cell layer plus inner plexiform layer (GCL+IPL) at diagnosis and 6 months after diagnosis. Results: The PRCP mRNA expression in EAON-induced mice was markedly higher than that in naïve mice. The mean plasma PRCP level was significantly higher in patients with ON than in controls. Plasma PRCP levels were negatively correlated with logMAR visual acuity at 6 months after diagnosis and differences in macular GCL+IPL thickness during an ON attack. A plasma PRCP level of 49.98 (pg/mL) predicted the recurrence of ON with a 75% sensitivity and 87.5% specificity. Conclusions: Patients with idiopathic acute ON had higher plasma PRCP levels, and this was positively correlated with final visual outcome and well-preserved macular GCL+IPL thickness during an ON attack. The increase in plasma PRCP level may reflect its compensatory secretion to counteract neuroinflammation in ON patients.

Nicotine suppresses crystalline silica-induced astrocyte activation and neuronal death by inhibiting NF-κB in the mouse hippocampus

AIMS

Exposure to crystalline silica (CS) in occupational settings induces chronic inflammation in the respiratory system and, potentially, the brain. Some workers are frequently concurrently exposed to both CS and nicotine. Here, we explored the impact of nicotine on CS-induced neuroinflammation in the mouse hippocampus.

METHODS

In this study, we established double-exposed models of CS and nicotine in C57BL/6 mice. To assess depression-like behavior, experiments were conducted at 3, 6, and 9 weeks. Serum inflammatory factors were analyzed by ELISA. Hippocampus was collected for RNA sequencing analysis and examining the gene expression patterns linked to inflammation and cell death. Microglia and astrocyte activation and hippocampal neuronal death were assessed using immunohistochemistry and immunofluorescence staining. Western blotting was used to analyze the NF-κB expression level.

RESULTS

Mice exposed to CS for 3 weeks showed signs of depression. This was accompanied by elevated IL-6 in blood, destruction of the blood-brain barrier, and activation of astrocytes caused by an increased NF-κB expression in the CA1 area of the hippocampus. The elevated levels of astrocyte-derived Lcn2 and upregulated genes related to inflammation led to higher neuronal mortality. Moreover, nicotine mitigated the NF-κB expression, astrocyte activation, and neuronal death, thereby ameliorating the associated symptoms.

CONCLUSION

Silica exposure induces neuroinflammation and neuronal death in the mouse hippocampal CA1 region and depressive behavior. However, nicotine inhibits CS-induced neuroinflammation and neuronal apoptosis, alleviating depressive-like behaviors in mice.

AZD1390, an ataxia telangiectasia mutated inhibitor, attenuates microglia-mediated neuroinflammation and ischemic brain injury

AIMS

Excessive neuroinflammation mediated mainly by microglia plays a crucial role in ischemic stroke. AZD1390, an ataxia telangiectasia mutated (ATM) specific inhibitor, has been shown to promote radio-sensitization and survival in central nervous system malignancies, while the role of AZD1390 in ischemic stroke remains unknown.

METHODS

Real-time PCR, western blot, immunofluorescence staining, flow cytometry and enzyme-linked immunosorbent assays were used to assess the activation of microglia and the release of inflammatory cytokines. Behavioral tests were performed to measure neurological deficits. 2,3,5-Triphenyltetrazolium chloride staining was conducted to assess the infarct volume. The activation of NF-κB signaling pathway was explored through immunofluorescence staining, western blot, co-immunoprecipitation and proximity ligation assay.

RESULTS

The level of pro-inflammation cytokines and activation of NF-κB signaling pathway was suppressed by AZD1390 in vitro and in vivo. The behavior deficits and infarct size were partially restored with AZD1390 treatment in experimental stroke. AZD1390 restrict ubiquitylation and sumoylation of the essential regulatory subunit of NF-κB (NEMO) in an ATM-dependent and ATM-independent way respectively, which reduced the activation of the NF-κB pathway.

CONCLUSION

AZD1390 suppressed NF-κB signaling pathway to alleviate ischemic brain injury in experimental stroke, and attenuated microglia activation and neuroinflammation, which indicated that AZD1390 might be an attractive agent for the treatment of ischemic stroke.

Human Glial Cells as Innovative Targets for the Therapy of Central Nervous System Pathologies

In vitro and preclinical in vivo research in the last 35 years has clearly highlighted the crucial physiopathological role of glial cells, namely astrocytes/microglia/oligodendrocytes and satellite glial cells/Schwann cells in the central and peripheral nervous system, respectively. Several possible pharmacological targets to various neurodegenerative disorders and painful conditions have therefore been successfully identified, including receptors and enzymes, and mediators of neuroinflammation. However, the translation of these promising data to a clinical setting is often hampered by both technical and biological difficulties, making it necessary to perform experiments on human cells and models of the various diseases. In this review we will, therefore, summarize the most relevant data on the contribution of glial cells to human pathologies and on their possible pharmacological modulation based on data obtained in post-mortem tissues and in iPSC-derived human brain cells and organoids. The possibility of an in vivo visualization of glia reaction to neuroinflammation in patients will be also discussed.

The Influence of Microglia on Neuroplasticity and Long-Term Cognitive Sequelae in Long COVID: Impacts on Brain Development and Beyond

Microglial cells, the immune cells of the central nervous system, are key elements regulating brain development and brain health. These cells are fully responsive to stressors, microenvironmental alterations and are actively involved in the construction of neural circuits in children and the ability to undergo full experience-dependent plasticity in adults. Since neuroinflammation is a known key element in the pathogenesis of COVID-19, one might expect the dysregulation of microglial function to severely impact both functional and structural plasticity, leading to the cognitive sequelae that appear in the pathogenesis of Long COVID. Therefore, understanding this complex scenario is mandatory for establishing the possible molecular mechanisms related to these symptoms. In the present review, we will discuss Long COVID and its association with reduced levels of BDNF, altered crosstalk between circulating immune cells and microglia, increased levels of inflammasomes, cytokines and chemokines, as well as the alterations in signaling pathways that impact neural synaptic remodeling and plasticity, such as fractalkines, the complement system, the expression of SIRPα and CD47 molecules and altered matrix remodeling. Together, these complex mechanisms may help us understand consequences of Long COVID for brain development and its association with altered brain plasticity, impacting learning disabilities, neurodevelopmental disorders, as well as cognitive decline in adults.

The Role of NRF2 in Cerebrovascular Protection: Implications for Vascular Cognitive Impairment and Dementia (VCID)

Vascular cognitive impairment and dementia (VCID) represents a broad spectrum of cognitive decline secondary to cerebral vascular aging and injury. It is the second most common type of dementia, and the prevalence continues to increase. Nuclear factor erythroid 2-related factor 2 (NRF2) is enriched in the cerebral vasculature and has diverse roles in metabolic balance, mitochondrial stabilization, redox balance, and anti-inflammation. In this review, we first briefly introduce cerebrovascular aging in VCID and the NRF2 pathway. We then extensively discuss the effects of NRF2 activation in cerebrovascular components such as endothelial cells, vascular smooth muscle cells, pericytes, and perivascular macrophages. Finally, we summarize the clinical potential of NRF2 activators in VCID.

Targeting Vascular Impairment, Neuroinflammation, and Oxidative Stress Dynamics with Whole-Body Cryotherapy in Multiple Sclerosis Treatment

Multiple sclerosis (MS), traditionally perceived as a neurodegenerative disease, exhibits significant vascular alternations, including blood-brain barrier (BBB) disruption, which may predispose patients to increased cardiovascular risks. This vascular dysfunction is intricately linked with the infiltration of immune cells into the central nervous system (CNS), which plays a significant role in perpetuating neuroinflammation. Additionally, oxidative stress serves not only as a byproduct of inflammatory processes but also as an active contributor to neural damage. The synthesis of these multifaceted aspects highlights the importance of understanding their cumulative impact on MS progression. This review reveals that the triad of vascular damage, chronic inflammation, and oxidative imbalance may be considered interdependent processes that exacerbate each other, underscoring the need for holistic and multi-targeted therapeutic approaches in MS management. There is a necessity for reevaluating MS treatment strategies to encompass these overlapping pathologies, offering insights for future research and potential therapeutic interventions. Whole-body cryotherapy (WBCT) emerges as one of the potential avenues for holistic MS management approaches which may alleviate the triad of MS progression factors in multiple ways.

Possible Role of Cannabis in the Management of Neuroinflammation in Patients with Post-COVID Condition

The post-COVID condition (PCC) is a pathology stemming from COVID-19, and studying its pathophysiology, diagnosis, and treatment is crucial. Neuroinflammation causes the most common manifestations of this disease including headaches, fatigue, insomnia, depression, anxiety, among others. Currently, there are no specific management proposals; however, given that the inflammatory component involves cytokines and free radicals, these conditions must be treated to reduce the current symptoms and provide neuroprotection to reduce the risk of a long-term neurodegenerative disease. It has been shown that cannabis has compounds with immunomodulatory and antioxidant functions in other pathologies. Therefore, exploring this approach could provide a viable therapeutic option for PCC, which is the purpose of this review. This review involved an exhaustive search in specialized databases including PubMed, PubChem, ProQuest, EBSCO, Scopus, Science Direct, Web of Science, and Clinical Trials. Phytocannabinoids, including cannabidiol (CBD), cannabigerol (CBG), and Delta-9-tetrahydrocannabinol (THC), exhibit significant antioxidative and anti-inflammatory properties and have been shown to be an effective treatment for neuroinflammatory conditions. These compounds could be promising adjuvants for PCC alone or in combination with other antioxidants or therapies. PCC presents significant challenges to neurological health, and neuroinflammation and oxidative stress play central roles in its pathogenesis. Antioxidant therapy and cannabinoid-based approaches represent promising areas of research and treatment for mitigating adverse effects, but further studies are needed.

Natural Compounds Oridonin and Shikonin Exhibit Potentially Beneficial Regulatory Effects on Select Functions of Microglia

Accumulating evidence indicates that the adverse neuroimmune activation of microglia, brain immunocytes that support neurons, contributes to a range of neuroinflammatory disorders, including Alzheimer's disease. Correcting the abnormal functions of microglia is a potential therapeutic strategy for these diseases. Nucleotide-binding domain leucine-rich repeat and pyrin domain-containing receptor (NLRP) 3 inflammasomes are implicated in adverse microglial activation and their inhibitors, such as the natural compounds oridonin and shikonin, reduce microglial immune responses. We hypothesized that some of the beneficial effects of oridonin and shikonin on microglia are independent of their suppression of NLRP3 inflammasomes. Murine and human microglia-like cells were stimulated with bacterial lipopolysaccharide (LPS) only, which did not induce NLRP3 inflammasome activation or the resulting secretion of interleukin (IL)-1β, allowing for the identification of other anti-inflammatory effects. Under these experimental conditions, both oridonin and shikonin reduced nitric oxide (NO) secretion and the cytotoxicity of BV-2 murine microglia towards HT-22 murine neuronal cells, but upregulated BV-2 cell phagocytic activity. Only oridonin inhibited the secretion of tumor necrosis factor (TNF) by stimulated BV-2 microglia, while only shikonin suppressed the respiratory burst response of human HL-60 microglia-like cells. This observed discrepancy indicates that these natural compounds may have different molecular targets in microglia. Overall, our results suggest that oridonin and shikonin should be further investigated as pharmacological agents capable of correcting dysfunctional microglia, supporting their potential use in neuroinflammatory disorders.

Molecular and Cellular Involvement in CIPN

Many anti-cancer drugs, such as taxanes, platinum compounds, vinca alkaloids, and proteasome inhibitors, can cause chemotherapy-induced peripheral neuropathy (CIPN). CIPN is a frequent and harmful side effect that affects the sensory, motor, and autonomic nerves, leading to pain, numbness, tingling, weakness, and reduced quality of life. The causes of CIPN are not fully known, but they involve direct nerve damage, oxidative stress, inflammation, DNA damage, microtubule dysfunction, and altered ion channel activity. CIPN is also affected by genetic, epigenetic, and environmental factors that modulate the risk and intensity of nerve damage. Currently, there are no effective treatments or prevention methods for CIPN, and symptom management is mostly symptomatic and palliative. Therefore, there is a high demand for better understanding of the cellular and molecular mechanisms involved in CIPN, as well as the development of new biomarkers and therapeutic targets. This review gives an overview of the current knowledge and challenges in the field of CIPN, focusing on the biological and molecular mechanisms underlying this disorder.

Virus-Induced Epilepsy vs. Epilepsy Patients Acquiring Viral Infection: Unravelling the Complex Relationship for Precision Treatment

The intricate relationship between viruses and epilepsy involves a bidirectional interaction. Certain viruses can induce epilepsy by infecting the brain, leading to inflammation, damage, or abnormal electrical activity. Conversely, epilepsy patients may be more susceptible to viral infections due to factors, such as compromised immune systems, anticonvulsant drugs, or surgical interventions. Neuroinflammation, a common factor in both scenarios, exhibits onset, duration, intensity, and consequence variations. It can modulate epileptogenesis, increase seizure susceptibility, and impact anticonvulsant drug pharmacokinetics, immune system function, and brain physiology. Viral infections significantly impact the clinical management of epilepsy patients, necessitating a multidisciplinary approach encompassing diagnosis, prevention, and treatment of both conditions. We delved into the dual dynamics of viruses inducing epilepsy and epilepsy patients acquiring viruses, examining the unique features of each case. For virus-induced epilepsy, we specify virus types, elucidate mechanisms of epilepsy induction, emphasize neuroinflammation's impact, and analyze its effects on anticonvulsant drug pharmacokinetics. Conversely, in epilepsy patients acquiring viruses, we detail the acquired virus, its interaction with existing epilepsy, neuroinflammation effects, and changes in anticonvulsant drug pharmacokinetics. Understanding this interplay advances precision therapies for epilepsy during viral infections, providing mechanistic insights, identifying biomarkers and therapeutic targets, and supporting optimized dosing regimens. However, further studies are crucial to validate tools, discover new biomarkers and therapeutic targets, and evaluate targeted therapy safety and efficacy in diverse epilepsy and viral infection scenarios.

Ultrasonographic Contrast and Therapeutic Effects of Hydrogen Peroxide-Responsive Nanoparticles in a Rat Model with Sciatic Neuritis

Purpose

Peripheral nerve damage lacks an appropriate diagnosis consistent with the patient's symptoms, despite expensive magnetic resonance imaging or electrodiagnostic assessments, which cause discomfort. Ultrasonography is valuable for diagnosing and treating nerve lesions; however, it is unsuitable for detecting small lesions. Poly(vanillin-oxalate) (PVO) nanoparticles are prepared from vanillin, a phytochemical with antioxidant and anti-inflammatory properties. Previously, PVO nanoparticles were cleaved by H2O2 to release vanillin, exert therapeutic efficacy, and generate CO2 to increase ultrasound contrast. However, the role of PVO nanoparticles in peripheral nerve lesion models is still unknown. Herein, we aimed to determine whether PVO nanoparticles can function as contrast and therapeutic agents for nerve lesions.

Methods

To induce sciatic neuritis, rats were administered a perineural injection of carrageenan using a nerve stimulator under ultrasonographic guidance, and PVO nanoparticles were injected perineurally to evaluate ultrasonographic contrast and therapeutic effects. Reverse transcription-quantitative PCR was performed to detect mRNA levels of pro-inflammatory cytokines, ie, tumor necrosis factor-α, interleukin-6, and cyclooxygenase-2.

Results

In the rat model of sciatic neuritis, PVO nanoparticles generated CO2 bubbles to increase ultrasonographic contrast, and a single perineural injection of PVO nanoparticles suppressed the expression of tumor necrosis factor-α, interleukin-6, and cyclooxygenase-2, reduced the expression of F4/80, and increased the expression of GAP43.

Conclusion

The results of the current study suggest that PVO nanoparticles could be developed as ultrasonographic contrast agents and therapeutic agents for nerve lesions.

AIBP controls TLR4 inflammarafts and mitochondrial dysfunction in a mouse model of Alzheimer's disease

Microglia-driven neuroinflammation plays an important role in the development of Alzheimer's disease (AD). Microglia activation is accompanied by the formation and chronic maintenance of TLR4 inflammarafts, defined as enlarged and cholesterol-rich lipid rafts serving as an assembly platform for TLR4 dimers and complexes of other inflammatory receptors. The secreted apoA-I binding protein (APOA1BP or AIBP) binds TLR4 and selectively targets cholesterol depletion machinery to TLR4 inflammaraft expressing inflammatory, but not homeostatic microglia. Here we demonstrated that amyloid-beta (Aβ) induced formation of TLR4 inflammarafts in microglia in vitro and in the brain of APP/PS1 mice. Mitochondria in Apoa1bp-/- APP/PS1 microglia were hyperbranched and cupped, which was accompanied by increased ROS and the dilated ER. The size and number of Aβ plaques and neuronal cell death were significantly increased, and the animal survival was decreased in Apoa1bp-/- APP/PS1 compared to APP/PS1 female mice. These results suggest that AIBP exerts control of TLR4 inflammarafts and mitochondrial dynamics in microglia and plays a protective role in AD associated oxidative stress and neurodegeneration.

Hydroxytyrosol Alleviates Obesity-Induced Cognitive Decline by Modulating the Expression Levels of Brain-Derived Neurotrophic Factors and Inflammatory Factors in Mice

Hydroxytyrosol (HT; 3,4-dihydroxyphenyl ethanol) is an important functional polyphenol in olive oil. Our study sought to evaluate the protective effects and underlying mechanisms of HT on obesity-induced cognitive impairment. A high-fat and high-fructose-diet-induced obese mice model was treated with HT for 14 weeks. The results show that HT improved the learning and memory abilities and enhanced the expressions of brain-derived neurotrophic factors (BDNFs) and postsynaptic density proteins, protecting neuronal and synaptic functions in obese mice. Transcriptomic results further confirmed that HT improved cognitive impairment by regulating gene expression in neural system development and synaptic function-related pathways. Moreover, HT treatment alleviated neuroinflammation in the brain of obese mice. To sum up, our results indicated that HT can alleviate obesity-induced cognitive dysfunction by enhancing BDNF expression and alleviating neuroinflammation in the brain, which also means that HT may become a potentially useful nutritional supplement to alleviate obesity-induced cognitive decline.

Long-Term Impact of Diffuse Traumatic Brain Injury on Neuroinflammation and Catecholaminergic Signaling: Potential Relevance for Parkinson's Disease Risk

Traumatic brain injury (TBI) is associated with an increased risk of developing Parkinson's disease (PD), though the exact mechanisms remain unclear. TBI triggers acute neuroinflammation and catecholamine dysfunction post-injury, both implicated in PD pathophysiology. The long-term impact on these pathways following TBI, however, remains uncertain. In this study, male Sprague-Dawley rats underwent sham surgery or Marmarou's impact acceleration model to induce varying TBI severities: single mild TBI (mTBI), repetitive mild TBI (rmTBI), or moderate-severe TBI (msTBI). At 12 months post-injury, astrocyte reactivity (GFAP) and microglial levels (IBA1) were assessed in the striatum (STR), substantia nigra (SN), and prefrontal cortex (PFC) using immunohistochemistry. Key enzymes and receptors involved in catecholaminergic transmission were measured via Western blot within the same regions. Minimal changes in these markers were observed, regardless of initial injury severity. Following mTBI, elevated protein levels of dopamine D1 receptors (DRD1) were noted in the PFC, while msTBI resulted in increased alpha-2A adrenoceptors (ADRA2A) in the STR and decreased dopamine beta-hydroxylase (DβH) in the SN. Neuroinflammatory changes were subtle, with a reduced number of GFAP+ cells in the SN following msTBI. However, considering the potential for neurodegenerative outcomes to manifest decades after injury, longer post-injury intervals may be necessary to observe PD-relevant alterations within these systems.

Maresin 1 Activates LGR6 to Alleviate Neuroinflammation via the CREB/JMJD3/IRF4 Pathway in a Rat Model of Subarachnoid Hemorrhage

Neuroinflammation is an early event of brain injury after subarachnoid hemorrhage (SAH). Whether the macrophage mediators in resolving inflammation 1 (MaR1) is involved in SAH pathogenesis is unknown. In this study, 205 male Sprague-Dawley rats were subjected to SAH via endovascular perforation in the experimental and control groups. MaR1 was dosed intranasally at 1 h after SAH, with LGR6 siRNA and KG-501, GSK-J4 administered to determine the signaling pathway. Neurobehavioral, histological and biochemical data were obtained from the animal groups with designated treatments. The results showed: (i) The leucine-rich repeat containing G protein-coupled receptor 6 (LGR6) was decreased after SAH and reached to the lowest level at 24 h after SAH. Jumonji d3 (JMJD3) protein levels tended to increase and peaked at 24 h after SAH. LGR6 and JMJD3 expression were co-localized with microglia. (ii) MaR1 administration mitigated short-term neurological deficits, brain edema and long-term neurobehavioral performance after SAH, and attenuated microglial activation and neutrophil infiltration. (iii) Knockdown of LGR6, inhibition of CREB phosphorylation or JMJD3 activity abolished the anti-neuroinflammatory effect of MaR1 on the expression of CREB, CBP, JMJD3, IRF4, IRF5, IL-1β, IL-6 and IL-10, thus prevented microglial activation and neutrophil infiltration. Together, the results show that MaR1 can activate LGR6 and affect CREB/JMJD3/IRF4 signaling to attenuate neuroinflammation after SAH, pointing to a potential pharmacological utility in this disorder.

The Interplay between Ferroptosis and Neuroinflammation in Central Neurological Disorders

Central neurological disorders are significant contributors to morbidity, mortality, and long-term disability globally in modern society. These encompass neurodegenerative diseases, ischemic brain diseases, traumatic brain injury, epilepsy, depression, and more. The involved pathogenesis is notably intricate and diverse. Ferroptosis and neuroinflammation play pivotal roles in elucidating the causes of cognitive impairment stemming from these diseases. Given the concurrent occurrence of ferroptosis and neuroinflammation due to metabolic shifts such as iron and ROS, as well as their critical roles in central nervous disorders, the investigation into the co-regulatory mechanism of ferroptosis and neuroinflammation has emerged as a prominent area of research. This paper delves into the mechanisms of ferroptosis and neuroinflammation in central nervous disorders, along with their interrelationship. It specifically emphasizes the core molecules within the shared pathways governing ferroptosis and neuroinflammation, including SIRT1, Nrf2, NF-κB, Cox-2, iNOS/NO·, and how different immune cells and structures contribute to cognitive dysfunction through these mechanisms. Researchers' findings suggest that ferroptosis and neuroinflammation mutually promote each other and may represent key factors in the progression of central neurological disorders. A deeper comprehension of the common pathway between cellular ferroptosis and neuroinflammation holds promise for improving symptoms and prognosis related to central neurological disorders.

The microglial innate immune protein PGLYRP1 mediates neuroinflammation and consequent behavioral changes

Peptidoglycan recognition protein 1 (PGLYRP1) is a pattern-recognition protein that mediates antibacterial actions and innate immune responses. Its expression and role in neuroinflammatory conditions remain unclear. We observed the upregulation of PGLYRP1 in inflamed human and mouse spinal cord and brain, with microglia being the primary cellular source. Experiments using a recombinant PGLYRP1 protein show that PGLYRP1 potentiates reactive gliosis, neuroinflammation, and consequent behavioral changes in multiple animal models of neuroinflammation. Furthermore, shRNA-mediated knockdown of Pglyrp1 gene expression attenuates this inflammatory response. In addition, we identify triggering receptor expressed on myeloid cell-1 (TREM1) as an interaction partner of PGLYRP1 and demonstrate that PGLYRP1 promotes neuroinflammation through the TREM1-Syk-Erk1/2-Stat3 axis in cultured glial cells. Taken together, our results reveal a role for microglial PGLYRP1 as a neuroinflammation mediator. Finally, we propose that PGLYRP1 is a potential biomarker and therapeutic target in various neuroinflammatory diseases.

Neuroinflammation of Microglial Regulation in Alzheimer's Disease: Therapeutic Approaches

Alzheimer's disease (AD) is a complex degenerative disease of the central nervous system that is clinically characterized by a progressive decline in memory and cognitive function. The pathogenesis of AD is intricate and not yet fully understood. Neuroinflammation, particularly microglial activation-mediated neuroinflammation, is believed to play a crucial role in increasing the risk, triggering the onset, and hastening the progression of AD. Modulating microglial activation and regulating microglial energy metabolic disorder are seen as promising strategies to intervene in AD. The application of anti-inflammatory drugs and the targeting of microglia for the prevention and treatment of AD has emerged as a new area of research interest. This article provides a comprehensive review of the role of neuroinflammation of microglial regulation in the development of AD, exploring the connection between microglial energy metabolic disorder, neuroinflammation, and AD development. Additionally, the advancements in anti-inflammatory and microglia-regulating therapies for AD are discussed.

Neuroprotective effect of taxifolin against aluminum chloride-induced dementia and pathological alterations in the brain of rats: possible involvement of toll-like receptor 4

Aluminum (Al) overexposure damages various organ systems, especially the nervous system. Regularly administered aluminum chloride (AlCl3) to rats causes dementia and pathophysiological alterations linked to Alzheimer's disease (AD). Taxifolin's neuroprotective effects against AlCl3-induced neurotoxicity in vitro and in vivo studies were studied. Taxifolin (0.1, 0.3, 1, 3, and 10 μM) was tested against AlCl3 (5 mM)-induced neurotoxicity in C6 and SH-SY5Y cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Additionally, neural morphology was examined by confocal microscopy. Additionally, taxifolin's mode of binding with the co-receptor of toll-like receptor 4 (TLR4), human myeloid differentiation-2 (hMD-2) was investigated. AlCl3 (25 mg/kg/d, i.p.) was administered to rats for 14 d, and from the eighth day, taxifolin (1, 2, and 5 mg/kg/d, i.p.) was given along with AlCl3. This study assessed memory impairment using the Morris water maze, plus maze, and pole tests. This study also performed measurement of oxidant (malondialdehyde [MDA] and nitrite), antioxidant (reduced glutathione), and inflammatory (myeloperoxidase [MPO] activity, TLR4 expression) parameters in rats' brain in addition to histopathology. The docking score for taxifolin with hMD-2 was found to be -4.38 kcal/mol. Taxifolin treatment reduced the neurotoxicity brought on by AlCl3 in both C6 and SH-SY5Y cells. Treatment with 10 μM taxifolin restored AlCl3-induced altered cell morphology. AlCl3 administration caused memory loss, oxidative stress, inflammation (increased MPO activity and TLR4 expression), and brain atrophy. Taxifolin treatment significantly improved the AlCl3-induced memory impairment. Taxifolin treatment also mitigated the histopathological and neurochemical consequences of repeated AlCl3 administration in rats. Thus, taxifolin may protect the brain against AD.

Endurance exercise has a negative impact on the onset of SOD1-G93A ALS in female mice and affects the entire skeletal muscle-motor neuron axis

Background

Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease characterized by the degeneration of motor neurons that leads to muscle wasting and atrophy. Epidemiological and experimental evidence suggests a causal relationship between ALS and physical activity (PA). However, the impact of PA on motor neuron loss and sarcopenia is still debated, probably because of the heterogeneity and intensities of the proposed exercises. With this study, we aimed to clarify the effect of intense endurance exercise on the onset and progression of ALS in the SOD1-G93A mouse model.

Methods

We randomly selected four groups of twelve 35-day-old female mice. SOD1-G93A and WT mice underwent intense endurance training on a motorized treadmill for 8 weeks, 5 days a week. During the training, we measured muscle strength, weight, and motor skills and compared them with the corresponding sedentary groups to define the disease onset. At the end of the eighth week, we analyzed the skeletal muscle-motor neuron axis by histological and molecular techniques.

Results

Intense endurance exercise anticipates the onset of the disease by 1 week (age of the onset: trained SOD1-G93A = 63.17 ± 2.25 days old; sedentary SOD1-G93A = 70.75 ± 2.45 days old). In SOD1-G93A mice, intense endurance exercise hastens the muscular switch to a more oxidative phenotype and worsens the denervation process by dismantling neuromuscular junctions in the tibialis anterior, enhancing the Wallerian degeneration in the sciatic nerve, and promoting motor neuron loss in the spinal cord. The training exacerbates neuroinflammation, causing immune cell infiltration in the sciatic nerve and a faster activation of astrocytes and microglia in the spinal cord.

Conclusion

Intense endurance exercise, acting on skeletal muscles, worsens the pathological hallmarks of ALS, such as denervation and neuroinflammation, brings the onset forward, and accelerates the progression of the disease. Our findings show the potentiality of skeletal muscle as a target for both prognostic and therapeutic strategies; the preservation of skeletal muscle health by specific intervention could counteract the dying-back process and protect motor neurons from death. The physiological characteristics and accessibility of skeletal muscle further enhance its appeal as a therapeutic target.

Investigating the structural network underlying brain-immune interactions using combined histopathology and neuroimaging: a critical review for its relevance in acute and long COVID-19

Current views on immunity support the idea that immunity extends beyond defense functions and is tightly intertwined with several other fields of biology such as virology, microbiology, physiology and ecology. It is also critical for our understanding of autoimmunity and cancer, two topics of great biological relevance and for critical public health considerations such as disease prevention and treatment. Central to this review, the immune system is known to interact intimately with the nervous system and has been recently hypothesized to be involved not only in autonomic and limbic bio-behaviors but also in cognitive function. Herein we review the structural architecture of the brain network involved in immune response. Furthermore, we elaborate upon the implications of inflammatory processes affecting brain-immune interactions as reported recently in pathological conditions due to SARS-Cov-2 virus infection, namely in acute and post-acute COVID-19. Moreover, we discuss how current neuroimaging techniques combined with ad hoc clinical autopsies and histopathological analyses could critically affect the validity of clinical translation in studies of human brain-immune interactions using neuroimaging. Advances in our understanding of brain-immune interactions are expected to translate into novel therapeutic avenues in a vast array of domains including cancer, autoimmune diseases or viral infections such as in acute and post-acute or Long COVID-19.

Mode of administration influences plasma levels of active Centella asiatica compounds in 5xFAD mice while markers of neuroinflammation remain unaltered

Introduction

A water extract of Centella asiatica (L.) Urban [Apiaceae] (CAW) has demonstrated cognitive-enhancing effects in mouse models of Alzheimer's disease and aging, the magnitude of which is influenced by whether CAW is delivered in the drinking water or the diet. These cognitive benefits are accompanied by improvements in oxidative stress and mitochondrial function in the brain, two pathways related to the neuroinflammatory response. The effect of CAW on neuroinflammation, however, has not been directly studied. Here, we investigated the effect of CAW on neuroinflammation in 5xFAD mice and compared plasma levels of CAW's active compounds following two modes of CAW administration.

Methods

Eight-to-nine-month-old male and female 5xFAD mice and their wild-type littermates were administered CAW in their diet or drinking water (0 or 1,000 mg/kg/day) for five weeks. Immunohistochemistry was performed for β-amyloid (Aβ), glial fibrillary acidic protein (GFAP), and Griffonia simplicifolia lectin I (GSL I) in the cortex and hippocampus. Gene expression of inflammatory mediators (IL-6, TNFα, IL-1β, TREM2, AIF1, CX3CR1, CX3CL1, CD36, C3AR1, RAGE, CCR6, CD3E) was measured in the deep grey matter.

Results

CAW decreased cortical Aβ plaque burden in female 5xFAD mice administered CAW in the drinking water but had no effect on Aβ plaques in other treatment groups. CAW did not impact elevated levels of GFAP or GSL I in 5xFAD mice, regardless of sex, brain region, or mode of CAW administration. In the deep grey matter, CAW increased C3AR1 expression in 5xFAD females administered CAW in the drinking water and decreased IL-1β expression in 5xFAD males administered CAW in the diet. CAW had no effect, however, on gene expression levels of any other inflammatory mediator in the deep grey, for either sex or mode of CAW administration. Mice administered CAW in the drinking water versus the diet had significantly higher plasma levels of CAW compounds.

Discussion

CAW had little impact on the neuroinflammatory markers selected for evaluation in the present study, suggesting that the cognitive benefits of CAW may not be mediated by an anti-inflammatory effect or that additional molecular markers are needed to fully characterize the effect of CAW on neuroinflammation.

Psychobiotics and the Microbiota-Gut-Brain Axis: Where Do We Go from Here?

The bidirectional relationship between the gut microbiota and the nervous system is known as the microbiota-gut-brain axis (MGBA). The MGBA controls the complex interactions between the brain, the enteric nervous system, the gut-associated immune system, and the enteric neuroendocrine systems, regulating key physiological functions such as the immune response, sleep, emotions and mood, food intake, and intestinal functions. Psychobiotics are considered tools with the potential to modulate the MGBA through preventive, adjunctive, or curative approaches, but their specific mechanisms of action on many aspects of health are yet to be characterized. This narrative review and perspectives article highlights the key paradigms needing attention as the scope of potential probiotics applications in human health increases, with a growing body of evidence supporting their systemic beneficial effects. However, there are many limitations to overcome before establishing the extent to which we can incorporate probiotics in the management of neuropsychiatric disorders. Although this article uses the term probiotics in a general manner, it remains important to study probiotics at the strain level in most cases.

Evaluating emerging drugs in phase II & III for the treatment of amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic Lateral Sclerosis is a rapidly progressive motor neuron disorder causing severe disability and premature death. Owing to the advances in uncovering ALS pathophysiology, efficient clinical trial design and research advocacy program, several disease-modifying drugs have been approved for treating ALS. Despite this progress, ALS remains a rapidly disabling and life shortening condition. There is a critical need for more effective therapies.

AREAS COVERED

Here, we reviewed the emerging ALS therapeutics undergoing phase II & III clinical trials. To identify the investigational drugs, we searched ALS and phase II/III trials that are active and recruiting or not yet recruiting on clinicaltrials.gov and Pharmaprojects database.

EXPERT OPINION

The current pipeline is larger and more diverse than ever, with drugs targeting potential genetic and retroviral causes of ALS and drugs targeting a wide array of downstream pathways, including RNA metabolism, protein aggregation, integrated stress response and neuroinflammation.We remain most excited about those that target direct causes of ALS, e.g. antisense oligonucleotides targeting causative genes. Drugs that eliminate abnormal protein aggregates are also up-and-coming. Eventually, because of the heterogeneity of ALS pathophysiology, biomarkers that determine which biological events are most important for an individual ALS patient are needed.

Emerging Molecular and Synaptic Targets for the Management of Chronic Pain Caused by Systemic Lupus Erythematosus

Patients with systemic lupus erythematosus (SLE) frequently experience chronic pain due to the limited effectiveness and safety profiles of current analgesics. Understanding the molecular and synaptic mechanisms underlying abnormal neuronal activation along the pain signaling pathway is essential for developing new analgesics to address SLE-induced chronic pain. Recent studies, including those conducted by our team and others using the SLE animal model (MRL/lpr lupus-prone mice), have unveiled heightened excitability in nociceptive primary sensory neurons within the dorsal root ganglia and increased glutamatergic synaptic activity in spinal dorsal horn neurons, contributing to the development of chronic pain in mice with SLE. Nociceptive primary sensory neurons in lupus animals exhibit elevated resting membrane potentials, and reduced thresholds and rheobases of action potentials. These changes coincide with the elevated production of TNFα and IL-1β, as well as increased ERK activity in the dorsal root ganglion, coupled with decreased AMPK activity in the same region. Dysregulated AMPK activity is linked to heightened excitability in nociceptive sensory neurons in lupus animals. Additionally, the increased glutamatergic synaptic activity in the spinal dorsal horn in lupus mice with chronic pain is characterized by enhanced presynaptic glutamate release and postsynaptic AMPA receptor activation, alongside the reduced activity of glial glutamate transporters. These alterations are caused by the elevated activities of IL-1β, IL-18, CSF-1, and thrombin, and reduced AMPK activities in the dorsal horn. Furthermore, the pharmacological activation of spinal GPR109A receptors in microglia in lupus mice suppresses chronic pain by inhibiting p38 MAPK activity and the production of both IL-1β and IL-18, as well as reducing glutamatergic synaptic activity in the spinal dorsal horn. These findings collectively unveil crucial signaling molecular and synaptic targets for modulating abnormal neuronal activation in both the periphery and spinal dorsal horn, offering insights into the development of analgesics for managing SLE-induced chronic pain.

Methamphetamine Enhancement of HIV-1 gp120-Mediated NLRP3 Inflammasome Activation and Resultant Proinflammatory Responses in Rat Microglial Cultures

Human Immunodeficiency Virus type 1 (HIV-1)-associated neurocognitive disorders (HANDs) remain prevalent in HIV-1-infected individuals despite the evident success of combined antiretroviral therapy (cART). The mechanisms underlying HAND prevalence in the cART era remain perplexing. Ample evidence indicates that HIV-1 envelope glycoprotein protein 120 (gp120), a potent neurotoxin, plays a pivotal role in HAND pathogenesis. Methamphetamine (Meth) abuse exacerbates HANDs, but how this occurs is not fully understood. We hypothesize that Meth exacerbates HANDs by enhancing gp120-mediated neuroinflammation. To test this hypothesis, we studied the effect of Meth on gp120-induced microglial activation and the resultant production of proinflammatory cytokines in primary rat microglial cultures. Our results show that Meth enhanced gp120-induced microglial activation, as revealed by immunostaining and Iba-1 expression, and potentiated gp120-mediated NLRP3 expression and IL-1β processing and release, as assayed by immunoblotting and ELISA. Meth also augmented the co-localization of NLRP3 and caspase-1, increased the numbers of NLRP3 puncta and ROS production, increased the levels of iNOS expression and NO production, and increased the levels of cleaved gasderminD (GSDMD-N; an executor of pyroptosis) in gp120-primed microglia. The Meth-associated effects were attenuated or blocked by MCC950, an NLRP3 inhibitor, or Mito-TEMPO, a mitochondrial superoxide scavenger. These results suggest that Meth enhances gp120-associated microglial NLRP3 activation and the resultant proinflammatory responses via mitochondria-dependent signaling.

Tamoxifen exerts direct and microglia-mediated effects preventing neuroinflammatory changes in the adult mouse hippocampal neurogenic niche

Tamoxifen-inducible systems are widely used in research to control Cre-mediated gene deletion in genetically modified animals. Beyond Cre activation, tamoxifen also exerts off-target effects, whose consequences are still poorly addressed. Here, we investigated the impact of tamoxifen on lipopolysaccharide (LPS)-induced neuroinflammatory responses, focusing on the neurogenic activity in the adult mouse dentate gyrus. We demonstrated that a four-day LPS treatment led to an increase in microglia, astrocytes and radial glial cells with concomitant reduction of newborn neurons. These effects were counteracted by a two-day tamoxifen pre-treatment. Through selective microglia depletion, we elucidated that both LPS and tamoxifen influenced astrogliogenesis via microglia mediated mechanisms, while the effects on neurogenesis persisted even in a microglia-depleted environment. Notably, changes in radial glial cells resulted from a combination of microglia-dependent and -independent mechanisms. Overall, our data reveal that tamoxifen treatment per se does not alter the balance between adult neurogenesis and astrogliogenesis but does modulate cellular responses to inflammatory stimuli exerting a protective role within the adult hippocampal neurogenic niche.

Reduced serum IgG galactosylation is associated with increased inflammation during relapses of neuromyelitis optica spectrum disorders

Background and Objective

Post-translational modifications of antibodies, with a specific focus on galactosylation, have garnered increasing attention in the context of understanding the pathogenesis and therapeutic implications of autoimmune diseases. However, the comprehensive scope and the clinical significance of antibody galactosylation in the context of Neuromyelitis Optica Spectrum Disorder (NMOSD) remain enigmatic.The primary aim of this research was to discern disparities in serum IgG galactosylation levels between individuals in the acute stage of NMOSD relapse and their age- and sex-matched healthy counterparts.

Methods

A total of fourteen untreated NMOSD patients experiencing an acute relapse phase, along with thirteen patients under medication, were enrolled, and an additional twelve healthy controls of the same age and gender were recruited for this investigation. Western blot and lectin enzyme techniques were used to determine the level of IgG galactosylation in the serum samples from these subjects. The expression of CD45+, CD3+, CD3+CD4+, CD3+CD8+, CD19+, and CD16+CD56+ in peripheral blood leukocytes was measured by flow cytometry. The enzyme-linked immunosorbent assay (ELISA) was also used to quantify the amounts of IgG. Magnetic particle luminescence assays are used to detect cytokines. Robust statistical analysis was executed to ascertain the potential associations between IgG galactosylation and the aforementioned immune indices.

Results

In the context of NMOSD relapses, serum IgG galactosylation exhibited a notable decrease in untreated patients (0.2482 ± 0.0261), while it remained comparatively stable in medicated patients when contrasted with healthy controls (0.3625 ± 0.0259) (p=0.0159). Furthermore, a noteworthy inverse correlation between serum IgG galactosylation levels and the Expanded Disability Status Scale (EDSS) score during NMOSD relapse was observed (r=-0.4142; p=0.0317). Notably, IgG galactosylation displayed an inverse correlation with NMOSD relapse among peripheral blood CD45+, CD3+, CD3+CD8+, CD19+ cells, as well as with IL-6 and IL-8. Nevertheless, it was not determined whether IgG galactosylation and CD3+CD4+ T cells or other cytokines are statistically significantly correlated.

Conclusion

Our research identified reduced IgG galactosylation in the serum of NMOSD patients during relapses, significantly correlated with disease severity, thereby providing a novel target for the diagnosis and treatment of NMOSD in the realm of medical research.

HER-096 is a CDNF-derived brain-penetrating peptidomimetic that protects dopaminergic neurons in a mouse synucleinopathy model of Parkinson's disease

Cerebral dopamine neurotrophic factor (CDNF) is an unconventional neurotropic factor that modulates unfolded protein response (UPR) pathway signaling and alleviates endoplasmic reticulum (ER) stress providing cytoprotective effects in different models of neurodegenerative disorders. Here, we developed a brain-penetrating peptidomimetic compound based on human CDNF. This compound called HER-096 shows similar potency and mechanism of action as CDNF, and promotes dopamine neuron survival, reduces α-synuclein aggregation and modulates UPR signaling in in vitro models. HER-096 is metabolically stable and able to penetrate to cerebrospinal (CSF) and brain interstitial fluids (ISF) after subcutaneous administration, with an extended CSF and brain ISF half-life compared to plasma. Subcutaneously administered HER-096 modulated UPR pathway activity, protected dopamine neurons, and reduced α-synuclein aggregates and neuroinflammation in substantia nigra of aged mice with synucleinopathy. Peptidomimetic HER-096 is a candidate for development of a disease-modifying therapy for Parkinson's disease with a patient-friendly route of administration.

Short-term lipopolysaccharide treatment leads to astrocyte activation in LRRK2 G2019S knock-in mice without loss of dopaminergic neurons

Background

The G2019S mutation of LRRK2, which enhances kinase activity of the protein, confers a substantial risk of developing Parkinson's disease (PD). However, the mutation demonstrates incomplete penetrance, suggesting the involvement of other genetic or environmental modulating factors. Here, we investigated whether LRRK2 G2019S knock-in (KI) mice treated with the inflammogen lipopolysaccharide (LPS) could model LRRK2 PD.

Results

We found that short-term (2 weeks) treatment with LPS did not result in the loss of dopaminergic neurons in either LRRK2 G2019S KI or wild-type (WT) mice. Compared with WT mice, LRRK2 G2019S-KI mice showed incomplete recovery from LPS-induced weight loss. In LRRK2 G2019S KI mice, LPS treatment led to upregulated phosphorylation of LRRK2 at the autophosphorylation site Serine 1292, which is known as a direct readout of LRRK2 kinase activity. LPS treatment caused a greater increase in the activated astrocyte marker glial fibrillary acidic protein (GFAP) in the striatum and substantia nigra of LRRK2 G2019S mice than in those of WT mice. The administration of caffeine, which was recently identified as a biomarker of resistance to developing PD in individuals with LRRK2 mutations, attenuated LPS-induced astrocyte activation specifically in LRRK2 G2019S KI mice.

Conclusions

Our findings suggest that 2 weeks of exposure to LPS is not sufficient to cause dopaminergic neuronal loss in LRRK2 G2019S KI mice but rather results in increased astrocyte activation, which can be ameliorated by caffeine.

Senescence: A DNA damage response and its role in aging and Neurodegenerative Diseases

Senescence is a complicated, multi-factorial, irreversible cell cycle halt that has a tumor-suppressing effect in addition to being a significant factor in aging and neurological diseases. Damaged DNA, neuroinflammation, oxidative stress and disrupted proteostasis are a few of the factors that cause senescence. Senescence is triggered by DNA damage which initiates DNA damage response. The DNA damage response, which includes the formation of DNA damage foci containing activated H2AX, which is a key factor in cellular senescence, is provoked by a double strand DNA break. Oxidative stress impairs cognition, inhibits neurogenesis, and has an accelerated aging effect. Senescent cells generate pro-inflammatory mediators known as senescence-associated secretory phenotype (SASP). These pro-inflammatory cytokines and chemokines have an impact on neuroinflammation, neuronal death, and cell proliferation. While it is tempting to think of neurodegenerative diseases as manifestations of accelerated aging and senescence, this review will present information on brain ageing and neurodegeneration as a result of senescence and DNA damage response.

Alterations of the blood-brain barrier during aging

The blood-brain barrier (BBB) is a complex and dynamic interface that regulates the exchange of molecules and cells between the blood and the central nervous system. It undergoes structural and functional changes during aging, which may compromise its integrity and contribute to the pathogenesis of neurodegenerative diseases. In recent years, advances in microscopy and high-throughput bioinformatics have allowed a more in-depth investigation of the aging mechanisms of BBB. This review summarizes age-related alterations of the BBB structure and function from six perspectives: endothelial cells, astrocytes, pericytes, basement membrane, microglia and perivascular macrophages, and fibroblasts, ranging from the molecular level to the human multi-system level. These basic components are essential for the proper functioning of the BBB. Recent imaging methods of BBB were also reviewed. Elucidation of age-associated BBB changes may offer insights into BBB homeostasis and may provide effective therapeutic strategies to protect it during aging.

The effects of urolithin A on poly I:C-induced microglial activation

Neuroinflammation can be triggered by various stimuli, including viral infections. Viruses can directly invade the brain and infect neuronal cells or indirectly trigger a "cytokine storm" in the periphery that eventually leads to microglial activation in the brain. While this initial activation of microglial cells is important for viral clearance, chronic activation leads to excessive inflammation and oxidative stress, which can be neurotoxic. Remarkebly, recent studies have shown that certain viruses such as influenza A virus, coronavirus, herpes virus and Epstein-Barr virus may be involved in the development of neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Therefore, it is important to find therapeutic strategies against chronic neuroinflammation triggered by viral infections. Here, we investigated the effects of urolithin A (UA) on microglial activation in vitro induced by a viral mimetic, poly I:C, in a triple co-culture system of neurons, astrocytes and microglial cells. Immunocytochemistry was used to perform a comprehensive single-cell analysis of the morphological changes of microglia as an indicator of their reactive state. Treatment with UA significantly prevented the poly I:C-induced reactive state of microglia, which was characterized by increased expression of the microglial activation markers CD68 and IBA-1. UA restored the poly I:C-induced morphology by restoring microglial ramification. In addition, UA was able to reduce the release of the pro-inflammatory mediators CCL2, TNF-α, and IL-1β and showed a trend toward attenuation of cellular ROS production in poly I:C-treated cultures. Overall, this study suggests that UA as a component of a healthy diet may help prevent virus-induced neuroinflammation and may have therapeutic potential for future studies to prevent or treat neurodegenerative diseases by targeting the associated neuroinflammatory processes.

The Abca7V1613M variant reduces Aβ generation, plaque load, and neuronal damage

BACKGROUND

Variants in ABCA7, a member of the ABC transporter superfamily, have been associated with increased risk for developing late onset Alzheimer's disease (LOAD).

METHODS

CRISPR-Cas9 was used to generate an Abca7V1613M variant in mice, modeling the homologous human ABCA7V1599M variant, and extensive characterization was performed.

RESULTS

Abca7V1613M microglia show differential gene expression profiles upon lipopolysaccharide challenge and increased phagocytic capacity. Homozygous Abca7V1613M mice display elevated circulating cholesterol and altered brain lipid composition. When crossed with 5xFAD mice, homozygous Abca7V1613M mice display fewer Thioflavin S-positive plaques, decreased amyloid beta (Aβ) peptides, and altered amyloid precursor protein processing and trafficking. They also exhibit reduced Aβ-associated inflammation, gliosis, and neuronal damage.

DISCUSSION

Overall, homozygosity for the Abca7V1613M variant influences phagocytosis, response to inflammation, lipid metabolism, Aβ pathology, and neuronal damage in mice. This variant may confer a gain of function and offer a protective effect against Alzheimer's disease-related pathology.

HIGHLIGHTS

ABCA7 recognized as a top 10 risk gene for developing Alzheimer's disease. Loss of function mutations result in increased risk for LOAD. V1613M variant reduces amyloid beta plaque burden in 5xFAD mice. V1613M variant modulates APP processing and trafficking in 5xFAD mice. V1613M variant reduces amyloid beta-associated damage in 5xFAD mice.

Folic Acid Rescues Dopaminergic Neurons in MPTP-Induced Mice by Inhibiting the NLRP3 Inflammasome and Ameliorating Mitochondrial Impairment

Parkinson's disease (PD) is marked by the degeneration of dopaminergic neurons of the substantia nigra (SN), with neuroinflammation and mitochondrial dysfunction being key contributors. The neuroprotective potential of folic acid (FA) in the dopaminergic system of PD was assessed in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model. MPTP (20 mg/kg of body weight) was administered to C57BL/6J mice to simulate PD symptoms followed by FA treatment (5 mg/kg of body weight). Behavioral tests, pole, rotarod, and open-field tests, evaluated motor function, while immunohistochemistry, ELISA, RT-qPCR, and Western blotting quantified neuroinflammation, oxidative stress markers, and mitochondrial function. FA supplementation considerably improved motor performance, reduced homocysteine levels and mitigated oxidative damage in the SN. The FA-attenuated activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome lessened glial cell activity and reduced neuroinflammation. At the molecular level, FA reduced DNA damage, downregulated phosphorylated p53, and induced the expression of peroxisome proliferator-activated receptor α coactivator 1α (PGC-1α), enhancing mitochondrial function. Therefore, FA exerts neuroprotection in MPTP-induced PD by inhibiting neuroinflammation via NLRP3 inflammasome suppression and promoting mitochondrial integrity through the p53-PGC-1α pathway. Notable limitations of our study include its reliance on a single animal model and the incompletely elucidated mechanisms underlying the impact of FA on mitochondrial dynamics. Future investigations will explore the clinical utility of FA and its molecular mechanisms, further advancing it as a potential therapeutic for managing and delaying the progression of PD.

Inhibition of phospholipase D promotes neurological function recovery and reduces neuroinflammation after spinal cord injury in mice

Introduction

Spinal cord injury (SCI) is a severely disabling disease. Hyperactivation of neuroinflammation is one of the main pathophysiological features of secondary SCI, with phospholipid metabolism playing an important role in regulating inflammation. Phospholipase D (PLD), a critical lipid-signaling molecule, is known to be involved in various physiological processes, including the regulation of inflammation. Despite this knowledge, the specific role of PLD in SCI remains unclear.

Methods

In this study, we constructed mouse models of SCI and administered PLD inhibitor (FIPI) treatment to investigate the efficacy of PLD. Additionally, transcriptome sequencing and protein microarray analysis of spinal cord tissues were conducted to further elucidate its mechanism of action.

Results

The results showed that PLD expression increased after SCI, and inhibition of PLD significantly improved the locomotor ability, reduced glial scarring, and decreased the damage of spinal cord tissues in mice with SCI. Transcriptome sequencing analysis showed that inhibition of PLD altered gene expression in inflammation regulation. Subsequently, the protein microarray analysis of spinal cord tissues revealed variations in numerous inflammatory factors. Biosignature analysis pointed to an association with immunity, thus confirming the results obtained from transcriptome sequencing.

Discussion

Collectively, these observations furnish compelling evidence supporting the anti-inflammatory effect of FIPI in the context of SCI, while also offering important insights into the PLD function which may be a potential therapeutic target for SCI.

STING-Dependent Signaling in Microglia or Peripheral Immune Cells Orchestrates the Early Inflammatory Response and Influences Brain Injury Outcome

While originally identified as an antiviral pathway, recent work has implicated that cyclic GMP-AMP-synthase-Stimulator of Interferon Genes (cGAS-STING) signaling is playing a critical role in the neuroinflammatory response to traumatic brain injury (TBI). STING activation results in a robust inflammatory response characterized by the production of inflammatory cytokines called interferons, as well as hundreds of interferon stimulated genes (ISGs). Global knock-out (KO) mice inhibiting this pathway display neuroprotection with evidence that this pathway is active days after injury; yet, the early neuroinflammatory events stimulated by STING signaling remain understudied. Furthermore, the source of STING signaling during brain injury is unknown. Using a murine controlled cortical impact (CCI) model of TBI, we investigated the peripheral immune and microglial response to injury utilizing male chimeric and conditional STING KO animals, respectively. We demonstrate that peripheral and microglial STING signaling contribute to negative outcomes in cortical lesion volume, cell death, and functional outcomes postinjury. A reduction in overall peripheral immune cell and neutrophil infiltration at the injury site is STING dependent in these models at 24 h. Transcriptomic analysis at 2 h, when STING is active, reveals that microglia drive an early, distinct transcriptional program to elicit proinflammatory genes including interleukin 1-β (IL-1β), which is lost in conditional knock-out mice. The upregulation of alternative innate immune pathways also occurs after injury in these animals, which supports a complex relationship between brain-resident and peripheral immune cells to coordinate the proinflammatory response and immune cell influx to damaged tissue after injury.

Mixed Metal Components in PM2.5 Contribute to Chemokine Receptor CCR5-Mediated Neuroinflammation and Neuropathological Changes in the Mouse Olfactory Bulb

Particulate matter, especially PM2.5, can invade the central nervous system (CNS) via the olfactory pathway to induce neurotoxicity. The olfactory bulb (OB) is the key component integrating immunoprotection and olfaction processing and is necessarily involved in the relevant CNS health outcomes. Here we show that a microglial chemokine receptor, CCR5, is the target of environmentally relevant PM2.5 in the OB to trigger neuroinflammation and then neuropathological injuries. Mechanistically, PM2.5-induced CCR5 upregulation results in the pro-inflammatory paradigm of microglial activation, which subsequently activates TLR4-NF-κB neuroinflammation signaling and induces neuropathological changes that are closely related to neurodegenerative disorders (e.g., Aβ deposition and disruption of the blood-brain barrier). We specifically highlight that manganese and lead in PM2.5 are the main contributors to CCR5-mediated microglial activation and neuroinflammation in synergy with aluminum. Our results uncover a possible pathway of PM2.5-induced neuroinflammation and identify the principal neurotoxic components, which can provide new insight into efficiently diminishing the adverse health effects of PM2.5.

Histaminergic System and Vestibular Function in Normal and Pathological Conditions

Most neurotransmitter systems are represented in the central and peripheral vestibular system and are thereby involved both in normal vestibular signal processing and the pathophysiology of vestibular disorders. However, there is a special relationship between the vestibular system and the histaminergic system. The purpose of this review is to document how the histaminergic system interferes with normal and pathological vestibular function. In particular, we will discuss neurobiological mechanisms such as neuroinflammation that involve histamine to modulate and allow restoration of balance function in the situation of a vestibular insult. These adaptive mechanisms represent targets of histaminergic pharmacological compounds capable of restoring vestibular function in pathological situations. The clinical use of drugs targeting the histaminergic system in various vestibular disorders is critically discussed.

Vagus nerve stimulation as a promising neuroprotection for ischemic stroke via α7nAchR-dependent inactivation of microglial NLRP3 inflammasome

Ischemic stroke is a major cause of disability and death worldwide, and its management requires urgent attention. Previous studies have shown that vagus nerve stimulation (VNS) exerts neuroprotection in ischemic stroke by inhibiting neuroinflammation and apoptosis. In this study, we evaluated the timing for VNS intervention in ischemic stroke, and the underlying mechanisms  of VNS-induced neuroprotection. Mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 60 min. The left vagus nerve at cervical level was exposed and attached to an electrode connected to a low-frequency electrical stimulator. Vagus nerve stimulation (VNS) was given for 60 min before, during and after tMCAO (Pre-VNS, Dur-VNS, Post-VNS). Neurological function was assessed 24 h after reperfusion. We found that all the three VNS significantly protected against the tMCAO-induced injury evidenced by improved neurological function and reduced infarct volume. Moreover, the Pre-VNS was the most effective against the ischemic injury. We found that tMCAO activated microglia in the ischemic core and penumbra regions of the brain, followed by the NLRP3 inflammasome activation-induced neuroinflammation, which finally triggered neuronal death. VNS treatment preserved α7nAChR expression in the penumbra regions, inhibited NLRP3 inflammasome activation and ensuing neuroinflammation, rescuing cerebral neurons. The role of α7nAChR in microglial NLRP3 inflammasome activation in ischemic stroke was further validated using genetic manipulations, including Chrna7 knockout mice and microglial Chrna7 overexpression mice, as well as pharmacological interventions using the α7nAChR inhibitor methyllycaconitine and agonist PNU-282987. Collectively, this study demonstrates the potential of VNS as a safe and effective strategy to treat ischemic stroke, and presents a new approach targeting microglial NLRP3 inflammasome, which might be therapeutic for other inflammation-related diseases.

APOE2 gene therapy reduces amyloid deposition and improves markers of neuroinflammation and neurodegeneration in a mouse model of Alzheimer disease

Epidemiological studies show that individuals who carry the relatively uncommon APOE ε2 allele rarely develop Alzheimer disease, and if they do, they have a later age of onset, milder clinical course, and less severe neuropathological findings than people without this allele. The contrast is especially stark when compared with the major genetic risk factor for Alzheimer disease, APOE ε4, which has an age of onset several decades earlier, a more aggressive clinical course and more severe neuropathological findings, especially in terms of the amount of amyloid deposition. Here, we demonstrate that brain exposure to APOE ε2 via a gene therapy approach, which bathes the entire cortical mantle in the gene product after transduction of the ependyma, reduces Aβ plaque deposition, neurodegenerative synaptic loss, and, remarkably, reduces microglial activation in an APP/PS1 mouse model despite continued expression of human APOE ε4. This result suggests a promising protective effect of exogenous APOE ε2 and reveals a cell nonautonomous effect of the protein on microglial activation, which we show is similar to plaque-associated microglia in the brain of Alzheimer disease patients who inherit APOE ε2. These data increase the potential that an APOE ε2 therapeutic could be effective in Alzheimer disease, even in individuals born with the risky ε4 allele.