Microglial cell origin and phenotypes in health and disease. Nat Rev Immunol. 2011;11:775-787. [PMID: 22025055 DOI: 10.1038/nri3086]

Inhibiting ceramide synthase 5 expression in microglia decreases neuroinflammation after spinal cord injury

JOURNAL/nrgr/04.03/01300535-202510000-00026/figure1/v/2024-11-26T163120Z/r/image-tiff Microglia, the resident monocyte of the central nervous system, play a crucial role in the response to spinal cord injury. However, the precise mechanism remains unclear. To investigate the molecular mechanisms by which microglia regulate the neuroinflammatory response to spinal cord injury, we performed single-cell RNA sequencing dataset analysis, focusing on changes in microglial subpopulations. We found that the MG1 subpopulation emerged in the acute/subacute phase of spinal cord injury and expressed genes related to cell pyroptosis, sphingomyelin metabolism, and neuroinflammation at high levels. Subsequently, we established a mouse model of contusive injury and performed intrathecal injection of siRNA and molecular inhibitors to validate the role of ceramide synthase 5 in the neuroinflammatory responses and pyroptosis after spinal cord injury. Finally, we established a PC12-BV2 cell co-culture system and found that ceramide synthase 5 and pyroptosis-associated proteins were highly expressed to induce the apoptosis of neuron cells. Inhibiting ceramide synthase 5 expression in a mouse model of spinal cord injury effectively reduced pyroptosis. Furthermore, ceramide synthase 5-induced pyroptosis was dependent on activation of the NLRP3 signaling pathway. Inhibiting ceramide synthase 5 expression in microglia in vivo reduced neuronal apoptosis and promoted recovery of neurological function. Pla2g7 formed a "bridge" between sphingolipid metabolism and ceramide synthase 5-mediated cell death by inhibiting the NLRP3 signaling pathway. Collectively, these findings suggest that inhibiting ceramide synthase 5 expression in microglia after spinal cord injury effectively suppressed microglial pyroptosis mediated by NLRP3, thereby exerting neuroprotective effects.

Refining the interactions between microglia and astrocytes in Alzheimer's disease pathology

Microglia and astrocytes are central to the pathogenesis and progression of Alzheimer's Disease (AD), working both independently and collaboratively to regulate key pathological processes such as β-amyloid protein (Aβ) deposition, tau aggregation, neuroinflammation, and synapse loss. These glial cells interact through complex molecular pathways, including IL-3/IL-3Ra and C3/C3aR, which influence disease progression and cognitive decline. Emerging research suggests that modulating these pathways could offer therapeutic benefits. For instance, recombinant IL-3 administration in mice reduced Aβ plaques and improved cognitive functions, while C3aR inhibition alleviated Aβ and tau pathologies, restored synaptic function, and corrected immune dysregulation. However, the effects of these interactions are context-dependent. Acute C3/C3aR activation enhances microglial Aβ clearance, whereas chronic activation impairs it, highlighting the dual roles of glial signaling in AD. Furthermore, C3/C3aR signaling not only impacts Aβ clearance but also modulates tau pathology and synaptic integrity. Given AD's multifactorial nature, understanding the specific pathological environment is crucial when investigating glial cell contributions. The interplay between microglia and astrocytes can be both neuroprotective and neurotoxic, depending on the disease stage and brain region. This complexity underscores the need for targeted therapies that modulate glial cell activity in a context-specific manner. By elucidating the molecular mechanisms underlying microglia-astrocyte interactions, this research advances our understanding of AD and paves the way for novel therapeutic strategies aimed at mitigating neurodegeneration and cognitive decline in AD and related disorders.

Bioengineering innovations for neural organoids with enhanced fidelity and function

Neural organoids have been utilized to recapitulate different aspects of the developing nervous system. While hailed as promising experimental tools for studying human neural development and neuropathology, current neural organoids do not fully recapitulate the anatomy or microcircuitry-level functionality of the developing brain, spinal cord, or peripheral nervous system. In this review, we discuss emerging bioengineering approaches that control morphogen signals and biophysical microenvironments, which have improved the efficiency, fidelity, and utility of neural organoids. Furthermore, advancements in bioengineered tools have facilitated more sophisticated analyses of neural organoid functions and applications, including improved neural-bioelectronic interfaces and organoid-based information processing. Emerging bioethical issues associated with advanced neural organoids are also discussed. Future opportunities of neural organoid research lie in enhancing their fidelity, maturity, and complexity and expanding their applications in a scalable manner.

From immunobiology to intervention: Pathophysiology of autoimmune encephalitis

Autoimmune encephalitides (AEs) are neurological disorders caused by autoantibodies against neuronal and glial surface proteins. Nearly 20 years after their discovery, AE have evolved from being frequently misdiagnosed and untreated to a growing group of increasingly well-characterized conditions where patients benefit from targeted therapeutic strategies. This narrative review provides an immunological perspective on AE, focusing on NMDAR, CASPR2 and LGI1 encephalitis as the three most common forms of AE associated with anti-neuronal surface autoantibodies. We examine the autoreactive B cell subsets, the tolerance checkpoints that may fail, and the known triggers and predispositions contributing to disease. In addition, we discuss the roles of other immune cells, including T cells and microglia, in the pathogenesis of AE. By analyzing therapeutic strategies and treatment responses we draw insights into AE pathophysiology. Written at a time of transformative therapeutic advancements through cell therapies this work underscores the synergy between detailed immunological research and the development of innovative therapies.

Microbiome Gut-Brain-Axis: Impact on Brain Development and Mental Health

The current discovery that the gut microbiome, which contains roughly 100 trillion microbes, affects health and disease has catalyzed a boom in multidisciplinary research efforts focused on understanding this relationship. Also, it is commonly demonstrated that the gut and the CNS are closely related in a bidirectional pathway. A balanced gut microbiome is essential for regular brain activities and emotional responses. On the other hand, the CNS regulates the majority of GI physiology. Any disruption in this bidirectional pathway led to a progression of health problems in both directions, neurological and gastrointestinal diseases. In this review, we hope to shed light on the complicated connections of the microbiome-gut-brain axis and the critical roles of gut microbiome in the early development of the brain in order to get a deeper knowledge of microbiome-mediated pathological conditions and management options through rebalancing of gut microbiome.

The transcription factor MEF2C restrains microglial overactivation by inhibiting kinase CDK2

Microglial intrinsic immune checkpoints are essential safeguards to maintain immune homeostasis by preventing microglial overactivation, a process that substantially influences neurological disorders such as autism spectrum disorder (ASD). MEF2C is a crucial immune checkpoint that regulates microglial activation, but the mechanism remains unclear. We found that MEF2C-deficient (MEF2C-/-) induced microglia-like cells (iMGLs) derived from human pluripotent stem cells (hPSCs) exhibited overactivation following lipopolysaccharide stimulation, mimicking patterns observed in various neuroinflammatory disorders. High-throughput screening identified BMS265246, a cyclin-dependent kinase 2 (CDK2) inhibitor, which suppressed overactivation of MEF2C-/- iMGLs and normalized their inflammatory responses. Mechanistically, MEF2C transcriptionally upregulated p21 to inhibit CDK2 activation-mediated retinoblastoma protein (RB) degradation, thereby preventing transcription factor nuclear factor κB (NFκB) nuclear translocation and consequent microglial overactivation. BMS265246 treatment substantially ameliorated microglial overactivation and ASD-like behaviors in Mef2c-deficient mice. Our findings identify the MEF2C-p21-CDK2-RB-NFκB axis as a critical pathway to maintain microglial homeostasis and highlight CDK2 as a potential therapeutic target for neuroinflammation.

Novel subcellular regulatory mechanisms of protein homeostasis and its implications in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron degenerative disorder. Protein aggregates induce various forms of neuronal dysfunction and represent pathological hallmarks in ALS patients. Reducing protein aggregates could be a promising therapeutic strategy for ALS. While most studies have focused on cytoplasmic protein homeostasis, neurons adaptively reduce aggregates across subcellular compartments during stress through previously uncharacterized mechanisms. Here, we summarize novel compartment-specific proteostatic mechanisms: (1) the ERAD/RESET pathways, (2) HSPs-mediated nuclear sequestration, (3) mitochondrial aggregate import (MAGIC), (4) neurite-localized UPS/autophagosome and NMP, and (5) exopher-mediated extracellular disposal. These mechanisms collectively ensure cellular stress adaptation and provide novel therapeutic targets for ALS treatment.

Compensatory enhancement of orexinergic system functionality induced by amyloid-β protein: a neuroprotective response in Alzheimer's disease

Background

Amyloid-β protein (Aβ) accumulation is a defining characteristic of Alzheimer's disease (AD), resulting in neurodegeneration and a decline in cognitive function. Given orexin's well-documented role in enhancing memory and cognition, this study investigates its potential to regulate Aβ-induced neurotoxicity, offering new perspectives into AD management.

Methods

This paper simulated Aβ accumulation in the hippocampus of AD patients by administering Aβ1-42 oligomers into the bilateral hippocampal dentate gyrus of ICR mice. Inflammatory cytokines (IL-6, TNF-α) and orexin-A levels were measured by ELISA. Additionally, the excitability of orexinergic neurons was assessed by IHC targeting c-Fos expression. These methodologies evaluated the Aβ-induced neuroinflammation, orexinergic system functionality, and dexamethasone's (Dex) effects on these processes.

Results

Injection of Aβ1-42 oligomer resulted in elevated levels of IL-6, TNF-α, and orexin-A in the hippocampus, as well as increased excitability of orexinergic neurons in the lateral hypothalamus (LH). Dex treatment reduced neuroinflammation, causing a reduction in orexin-A levels and the excitability of orexinergic neurons.

Conclusion

Aβ-induced neuroinflammation is accompanied by enhanced levels of orexin-A and orexinergic neuron excitability. These findings suggest that the enhanced functionality of the orexinergic system may become a compensatory neuroprotective mechanism to counteract neuroinflammation and enhance cognitive function.

Berberine Exerts Neuroprotective Effects in Alzheimer's Disease by Switching Microglia M1/M2 Polarization Through PI3K-AKT Signaling

Berberine (BBR), a small molecule protoberberine isoquinoline alkaloid, is easy to cross the blood-brain barrier and is a potential drug for neurodegenerative diseases. Here, we explored the role and molecular mechanism of BBR in Alzheimer's disease (AD) progression. Weighted gene co-expression network analysis (WGCNA) was conducted to determine AD pathology-associated gene modules and differentially expressed genes (DEGs) were also identified. GO and KEGG analyses were performed for gene function and signaling pathway annotation. Cell counting kit-8 (CCK8) assay was applied to analyze cell viability. Immunofluorescence (IF) staining assay was conducted to measure the levels of polarization markers. The production of inflammatory cytokines was analyzed by enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) level and mitochondrial membrane potential (MMP) were detected using a ROS detection kit and a MMP Detection Kit (JC-1), respectively. AD pathology-associated DEGs were applied for GO function annotation and KEGG enrichment analysis, and the results uncovered that AD pathology was related to immune and inflammation. Lipopolysaccharide (LPS) exposure induced the M1 phenotype of microglia, and BBR suppressed LPS-induced M1 polarization and induced microglia toward M2 polarization. Through co-culture of microglia and neuronal cells, we found that BBR exerted a neuro-protective role by attenuating the injury of LPS-induced HMC3 on SH-SY5Y cells. Mechanically, BBR switched the M1/M2 phenotypes of microglia by activating PI3K-AKT signaling. In summary, BBR protected neuronal cells from activated microglia-mediated neuro-inflammation by switching the M1/M2 polarization in LPS-induced microglia via activating PI3K-AKT signaling. Key words Alzheimer's Disease, Berberine, Microglia polarization, Neuroinflammation, PI3K-AKT signaling.

The potential neuroprotective effect of empagliflozin against depressive-like behavior induced by chronic unpredictable mild stress in rats: Involvement of NLRP3 inflammasome

Depression is a prevalent and debilitating condition that has a severe negative impact on a person's life. Chronic stress exposure plays a substantial role in the development of depression. In the present study, rats were exposed to chronic unpredictable mild stress (CUMS) for four weeks. Empagliflozin (EMPA), a Sodium-Glucose Cotransporter-2 (SGLT-2) inhibitor, is an oral antidiabetic agent exhibiting antioxidant, anti-inflammatory, and antiapoptotic effects. This study aimed to examine the antidepressant effect of EMPA in an experimental animal model of depression induced by CUMS in rats and explore the probable underlying mechanisms. Rats were treated with EMPA, per-orally, at a dose of 10 mg/kg/day for four weeks. EMPA treatment counteracted CUMS-induced histopathological, biochemical and behavioral alterations. EMPA suppressed the CUMS-induced increase in the oxidative stress, inflammatory, and apoptotic markers, where levels of MDA, IL-1β, TNF-α, NF-κB, NLRP3 and active caspase 3 were reduced by 29.6 %, 24.8 %, 17.9 %, 36.6 %, 24.5 % and 41.5 %, respectively, compared to the disease group. Furthermore, EMPA decreased the level of the microglial activation marker, iba-1 by 24 % in comparison to the disease group. In addition, EMPA treatment decreased blood glucose levels by 39 %, decreased serum insulin levels by 60.6 %, decreased HOMA-IR by 76.5 % and increased GLUT 4 expression, compared to the CUMS group, all which proves that EMPA has an effect insulin signaling and alleviates insulin resistance. Our results conclude that modulating key factors involved in depression, such as inflammation, oxidative stress, and NLRP3 inflammasome pathway, accounts for the anti-depressant effect of EMPA.

Integration and functionality of human iPSC-derived microglia in a chimeric mouse retinal model

INTRODUCTION

Microglia, the resident immune cells of the central nervous system, play a pivotal role in maintaining homeostasis, responding to injury, and modulating neuroinflammation. However, the limitations of rodent models in accurately representing human microglia have posed significant challenges in the study of retinal diseases.

METHODS

PLX5622 was used to eliminate endogenous microglia in mice through oral and intraperitoneal administration, followed by transplantation of human induced pluripotent stem cell-derived microglia (hiPSC-microglia, iMG) into retinal explants to create a novel ex vivo chimeric model containing xenotransplanted microglia (xMG). The number and proportion of xMG in the retina were quantified using retinal flat-mounting and immunostaining. To evaluate the proliferative capacity and synaptic pruning ability of xMG, the expression of Ki-67 and the phagocytosis of synaptic proteins SV2 and PSD95 was assessed. The chimeric model was stimulated with LPS, and single-cell RNA sequencing (scRNA-seq) was used to analyze transcriptomic changes in iMG and xMG. Mouse IL-34 antibody neutralization experiments were performed, and the behavior of xMG in retinal degenerative Pde6b-/- mice was examined.

RESULTS

We demonstrated that xenotransplanted microglia (xMG) successfully migrated to and localized within the mouse retina, adopting homeostatic morphologies. Our approach achieved over 86% integration of human microglia, which maintained key functions including proliferation, immune responsiveness, and synaptic pruning over a 14-day culture period. scRNA-seq of xMG revealed a shift in microglial signatures compared to monoculture iMG, indicating a transition to a more in vivo-like phenotype. In retinal degenerative Pde6b-/- mice, xMG exhibited activation and migrated toward degenerated photoreceptors.

CONCLUSION

This model provides a powerful platform for studying human microglia in the retinal context, offering significant insights for advancing research into retinal degenerative diseases and developing potential therapeutic strategies. Future applications of this model include using patient-derived iPSCs to investigate disease-specific microglial behaviors, thereby enhancing our understanding of microglia-related pathogenesis.

Enhancing autophagy mitigates LPS-induced neuroinflammation by inhibiting microglial M1 polarization and neuronophagocytosis

Background

Autophagy, a regulator of inflammation, has been implicated in various central nervous system pathologies. Despite this, the role and mechanisms of autophagy in lipopolysaccharide (LPS)-induced neuroinflammation are not clear. This study investigated whether autophagy can play a neuroprotective role in LPS-induced neuroinflammation.

Methods

Primary microglial cells and male C57BL/6 J mice were treated with LPS, autophagy inhibitors (3-methyladenine, 3-MA), or autophagy activators (rapamycin). Cell viability, NF-κB pathway activation, pro-inflammatory cytokine expression, M1 polarization, autophagy markers, and neuronal damage were evaluated via various techniques including CCK-8 assay, Western blot analysis, ELISA, immunohistochemistry, and histological staining.

Results

LPS (1 μg/mL) effectively inhibited cell viability, stimulated the expression of IκB-α and NF-κB, and simultaneously suppressed autophagy protein expression. The pro-inflammatory cytokines IL-1β and IL-6 showed a significant increase. Contrary to the effect of 3-MA, the rapamycin treatment inhibited the polarization of microglia cells to the M1 type in the various groups of microglia cells after LPS stimulation. This was evidenced by decreased expression of cytokines IL-1β, IL-6, and CD86, and increased expression of Arg-1, IL-10, and CD206. In vivo experiments found that mice with injections of LPS and 3-MA in the lateral ventricle showed significantly increased expression of IκB-α and NF-κB in brain tissues, elevated levels of pro-inflammatory cytokines, decreased autophagy levels, and increased necrotic neurons. There was increased aggregation of microglia cells and increased neuronophagocytosis. Conversely, mice injected with rapamycin showed enhanced neuronal cell autophagy, decreased expression of pro-inflammatory cytokines and apoptosis, and reduced neuronophagocytosis.

Conclusion

Enhancing autophagy can effectively mitigate LPS-induced neuroinflammation by inhibiting microglial M1 polarization and neuronophagocytosis, thereby protecting neuronal integrity. These findings suggest potential therapeutic strategies targeting autophagy in neuroinflammatory conditions.

The roles and therapeutic potential of exosomal non-coding RNAs in microglia-mediated intercellular communication

Exosomes, which are small extracellular vesicles (sEVs), serve as versatile regulators of intercellular communication in the progression of various diseases, including neurological disorders. Among the diverse array of cargo they carry, non-coding RNAs (ncRNAs) play key regulatory roles in various pathophysiological processes. Exosomal ncRNAs derived from distinct cells modulate their reciprocal crosstalk locally or remotely, thereby mediating neurological diseases. Nevertheless, the emerging role of exosomal ncRNAsin microglia-mediated phenotypes remains largely unexplored. This review aims to summarise the biological functions of exosomal ncRNAs and the molecular mechanisms that underlie their impact on microglia-mediated intercellular communication, modulating neuroinflammation and synaptic functions within the landscape of neurological disorders. Furthermore, this review comprehensively described the potential applications of exosomal ncRNAs as diagnostic and prognostic biomarkers, as well as innovative therapeutic targets for the treatment of neurological diseases.

Innate and adaptive immunity in neurodegenerative disease

Neurodegenerative diseases (NDs) are a group of neurological disorders characterized by the progressive loss of selected neurons. Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common NDs. Pathologically, NDs are characterized by progressive failure of neural interactions and aberrant protein fibril aggregation and deposition, which lead to neuron loss and cognitive and behavioral impairments. Great efforts have been made to delineate the underlying mechanism of NDs. However, the very first trigger of these disorders and the state of the illness are still vague. Existing therapeutic strategies can relieve symptoms but cannot cure these diseases. The human immune system is a complex and intricate network comprising various components that work together to protect the body against pathogens and maintain overall health. They can be broadly divided into two main types: innate immunity, the first line of defense against pathogens, which acts nonspecifically, and adaptive immunity, which follows a defense process that acts more specifically and is targeted. The significance of brain immunity in maintaining the homeostatic environment of the brain, and its direct implications in NDs, has increasingly come into focus. Some components of the immune system have beneficial regulatory effects, whereas others may have detrimental effects on neurons. The intricate interplay and underlying mechanisms remain an area of active research. This review focuses on the effects of both innate and adaptive immunity on AD and PD, offering a comprehensive understanding of the initiation and regulation of brain immunity, as well as the interplay between innate and adaptive immunity in influencing the progression of NDs.

Glial polarization in neurological diseases: Molecular mechanisms and therapeutic opportunities

Glial cell polarization plays a pivotal role in various neurological disorders. In response to distinct stimuli, glial cells undergo polarization to either mitigate neurotoxicity or facilitate neural repair following injury, underscoring the importance of glial phenotypic polarization in modulating central nervous system function. This review presents an overview of glial cell polarization, focusing on astrocytes and microglia. It explores the involvement of glial polarization in neurological diseases such as Alzheimer's disease, Parkinson's disease, stroke, epilepsy, traumatic brain injury, amyotrophic lateral sclerosis, multiple sclerosis and meningoencephalitis. Specifically, it emphasizes the role of glial cell polarization in disease pathogenesis through mechanisms including neuroinflammation, neurodegeneration, calcium signaling dysregulation, synaptic dysfunction and immune response. Additionally, it summarizes various therapeutic strategies including pharmacological treatments, dietary supplements and cell-based therapies, aimed at modulating glial cell polarization to ameliorate brain dysfunction. Future research focused on the spatio-temporal manipulation of glial polarization holds promise for advancing precision diagnosis and treatment of neurological diseases.

A comprehensive review on the plant sources, pharmacological activities and pharmacokinetic characteristics of Syringaresinol

Syringaresinol, a phytochemical constituent belonging to lignan, is formed from two sinapyl alcohol units linked via a β-β linkage, which can be found in a wide variety of cereals and medicinal plants. Medical researches revealed that Syringaresinol possesses a broad spectrum of biological activities, including anti-inflammatory, anti-oxidation, anticancer, antibacterial, antiviral, neuroprotection, and vasodilation effects. These pharmacological properties lay the foundation for its use in treating various diseases such as inflammatory diseases, neurodegenerative disorders, diabetes and its complication, skin disorders, cancer, cardiovascular, and cerebrovascular diseases. As the demand for natural therapeutics increases, Syringaresinol has garnered significant attention for its pharmacological properties. Despite the extensive literature that highlights the various biological activities of this molecule, the underlying mechanisms and the interrelationships between these activities are rarely addressed from a comprehensive perspective. Moreover, no thorough comprehensive summary and evaluation of Syringaresinol has been conducted to offer recommendations for potential future clinical trials and therapeutic applications of this bioactive compound. Thus, a comprehensive review on Syringaresinol is essential to advance scientific understanding, assess its therapeutic applications, ensure safety, and guide future research efforts. This will ultimately contribute to its potential integration into clinical practice and public health. This study aims to provide a comprehensive overview of Syringaresinol on its sources and biological activities to provide insights into its therapeutic potential, and to provide a basis for high-quality studies to determine the clinical efficacy of this compound. Additionally, we explored the pharmacokinetics, toxicology, and drug development aspects of Syringaresinol to guide future research efforts. The review also discussed the limitations of current research on Syringaresinol and put forward some new perspectives and challenges, which laid a solid foundation for further study on clinical application and new drug development of Syringaresinol in the future.

Macrophage invasion into the Drosophila brain requires JAK/STAT-dependent MMP activation in the blood-brain barrier

The central nervous system is well-separated from external influences by the blood-brain barrier. Upon surveillance, infection or neuroinflammation, however, peripheral immune cells can enter the brain where they often cause detrimental effects. To invade the brain, immune cells not only have to breach cellular barriers, but they also need to traverse associated extracellular matrix barriers. Neither in vertebrates nor in invertebrates is it fully understood how these processes are molecularly controlled. We recently established Drosophila melanogaster as a model to elucidate peripheral immune cell invasion into the brain. Here, we show that neuroinflammation leads to the expression of Unpaired cytokines that activate the JAK/STAT signaling pathway in glial cells of the blood-brain barrier. This in turn triggers the expression of matrix metalloproteinases enabling remodeling of the extracellular matrix enclosing the fly brain and a subsequent invasion of immune cells into the brain. Our study demonstrates conserved mechanisms underlying immune cell invasion of the nervous system in invertebrates and vertebrates and could, thus, further contribute to understanding of JAK/STAT signaling during neuroinflammation.

Dihydromyricetin ameliorates neurotoxicity induced by high glucose through restraining ferroptosis by inhibiting JNK-inflammation pathway in HT22 cells

Diabetes mellitus is recognized as an important cause of cognitive dysfunction. Ferroptosis plays a key role in diabetic cognitive dysfunction (DCD). Dihydromyricetin (DHM) has promising neuronal protective effects, but it is unclear the mechanism. Here, the effects of DHM on HG-induced neurotoxicity in HT22 cells and its molecular mechanisms were investigated. Our results demonstrated that the viability of HG (125 mmol/L)-induced HT22 cells was significantly decreased. Furthermore, ferroptosis-related indicators, c-Jun N-terminal kinase (JNK)-inflammatory pathway, TNF-α, IL-1β, and mitochondrial morphology were measured. The results show that mitochondria of HT22 cells also showed wrinkled alterations in response to HG treatment. Meanwhile, the levels of glutathione (GSH) and glutathione peroxidase 4 (GPX4) were decreased, accompanied by an up-regulation of malondialdehyde (MDA), Fe2+, acyl-CoA synthetase long-chain family member 4 (ACSL4), and reactive oxygen species (ROS), indicating ferroptosis occurred in HG-induced HT22 cells. Furthermore, the levels of p-JNK, TNF-α, and IL-6 were up-regulated in HG-induced HT22 cells. DHM or JNK inhibitor SP600125 reversed these changes in HG-induced HT22 cells indicating that HG-induced neurotoxicity in HT22 cells may be associated with ferroptosis induced by the JNK-inflammatory factor pathway. Meanwhile, JNK agonist Anisomycin could attenuate these effects of DHM. Taken together, our data suggest that DHM can ameliorate HG-induced neurotoxicity in HT22 cells by inhibiting ferroptosis via the JNK-inflammatory signaling pathway. Hence, DHM may represent a novel and promising therapeutic intervention for DCD.

Crosstalk between SIRT1/Nrf2 signaling and NLRP3 inflammasome/pyroptosis as a mechanistic approach for the neuroprotective effect of linagliptin in Parkinson's disease

In recent years, special attention has been paid to highlighting the antiparkinsonian effect of linagliptin. However, the mechanism of its action has not yet been well investigated. The present study aimed to verify the neuroprotective effect of linagliptin in the rotenone model of Parkinson's disease (PD) and further explore its potential molecular mechanisms. Rats were intoxicated with rotenone (2 mg/kg/day; sc) and treated with linagliptin (10  mg/kg/day; po) for 14 consecutive days. The present finding showed that linagliptin ameliorated the histopathological changes of rotenone on substantia nigra and striata. Linagliptin decreased α-synuclein immunoreactivity along with an increase in tyrosine hydroxylase immunoreactivity and striatal dopamine content. This was reflected in the marked improvement of the behavior and motor deficits in rotenone-intoxicated rats. On the molecular level, linagliptin upregulated sirtuin 1 (SIRT1)/ nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, reduced ionized calcium-binding adaptor molecule 1 (Iba1) protein expression, restored glutathione (GSH) content, and elevated heme oxygenase-1 (HO-1) level in rats with rotenone intoxication. Moreover, linagliptin inhibited NOD-like receptor protein 3 (NLRP3)/caspase-1/interleukin-1β (IL-1β) cascade with subsequent reduction in gasdermin D (GSDMD) expression. Therefore, the present study reveals the ability of linagliptin, through the activation of SIRT1/Nrf2 signaling, to suppress NLRP3 inflammasome-mediated pyroptosis and protect against rotenone-induced parkinsonism.

Cordyceps militaris and Armillaria mellea formula alleviates depressive behaviors via microglia regulation in an unpredictable chronic mild stress animal model

Background and aim

Cordyceps militaris (CM) and Armillaria mellea (AM) are medicinal mushrooms with potential applications in the treatment of mood disorders, including depression and anxiety. While research suggests that both CM and AM possess anti-inflammatory properties and hold potential for treating depression when administered separately, there is limited knowledge about their efficacy when combined in a formula, as well as the underlying mechanism involving the modulation of microglia.

Experimental procedure

Rats received oral administrations of the low-dose formulation, medium-dose formulation, and high-dose formulation over 28 consecutive days as part of the UCMS protocols. The concentrations of serotonin, dopamine, and the corresponding metabolites in the rat prefrontal cortex and hippocampus were assessed. Blood samples were collected to examine corticosterone levels, and the brains were dissected for evaluating activated microglia morphologies and associated pro- and anti-inflammatory signaling pathways.

Results and conclusion

The CM-AM formula effectively averted abnormal behaviors triggered by UCMS, such as anhedonia and hypoactivity, and decreased the turnover rate of monoamines in both the prefrontal cortex and hippocampus. The formula mitigated the increase in serum corticosterone levels induced by chronic stress. Furthermore, the formula alleviated stress-induced microglia activation in the hippocampus, achieving this by down-regulating hyperactivated pro-inflammatory proteins and up-regulating hypoactivated anti-inflammatory proteins in the hippocampus. The antidepressant-like effects potentially stemming from the regulation of neurotransmitters and immunomodulation, likely by restoring the balance of M1 and M2 microglia fractions in the hippocampus. Consequently, the CM-AM formula could be explored as a prospective complementary and alternative therapy for depression.

Modulation of the central nervous system immune response and neuroinflammation via Wnt signaling in health and neurodegenerative diseases

The immune response in the central nervous system (CNS) is a highly specialized and tightly regulated process essential for maintaining neural health and protecting against pathogens and injuries. The primary immune cells within the CNS include microglia, astrocytes, T cells, and B cells. They work together, continuously monitor the CNS environment for signs of infection, injury, or disease, and respond by phagocytosing debris, releasing cytokines, and recruiting other immune cells. In addition to providing neuroprotection, these immune responses must be carefully balanced to prevent excessive inflammation that can lead to neuronal damage and contribute to neurodegenerative diseases. Dysregulated immune responses in the CNS are implicated in various neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Wnt signaling is a crucial pathway in the CNS that regulates various cellular processes critical for brain development, function, and maintenance. Despite enhancing immune responses in the health CNS, dysregulated Wnt signaling exacerbates neuroinflammation in the neurodegenerative brains. This review summarized the role of Wnt signaling in regulating immune response under different conditions. We then examined the role of immune response in healthy brains and during the development of neurodegenerative diseases. We also discussed therapeutic intervention in various neurodegenerative diseases through the modulation of the Wnt signaling pathway and neuroinflammation and highlighted challenges and limitations in current clinical trials.

Exploring the Synergistic Effects of Erinacines on Microglial Regulation and Alzheimer's Pathology Under Metabolic Stress

BACKGROUND

Hericium erinaceus mycelium and its constituents, erinacines A and S, have shown neuroprotective effects in APP/PS1 transgenic mice; however, the precise mechanisms by which they modulate microglial phenotypes remain unclear. Our study is the first to explore the effect of erinacines on microglia morphology and the underlying mechanisms using a novel primary mixed glia cell model and advanced bioinformatic tools. Furthermore, we emphasize the clinical relevance by evaluating erinacines in a metabolically stressed APP/PS1 mouse model, which more accurately reflects the complexities of human Alzheimer's disease (AD), where metabolic syndrome is a common comorbidity.

METHODS

Rat primary mixed glial cultures were used to simulate the spectrum of microglial phenotypes, particularly the transition from immature to mature states. Microarray sequencing, along with Connectivity Map, ConsensusPathDB, and Gene Set Enrichment Analysis, identified pathways influenced by erinacines. The therapeutic efficacy was further evaluated in metabolically stressed APP/PS1 mice.

RESULTS

Erinacines significantly promoted the development of a ramified, neuroprotective microglial phenotype. Bioinformatics revealed potential modulation of microglia via histone deacetylase inhibition, actin filament dynamics, and synaptic structure modification-pathways not previously linked to erinacines in AD. Importantly, erinacines significantly lower fasting blood glucose and insulin levels while reducing amyloid-beta plaque burden, suppressing hyperactivated glial responses, and enhancing neurogenesis in the metabolically stressed APP/PS1 mice.

CONCLUSION

Our findings demonstrate the dual action of erinacines in modulating microglia morphology and phenotype while providing neuroprotection in a model that closely mimic the complexities of human Alzheimer's disease. Additionally, this study provides the foundation for understanding the potential mechanisms of action of erinacines, highlighting their promise as a novel treatment approach for Alzheimer's, particularly in cases complicated by metabolic dysfunction.

Role of Noncoding RNAs in Modulating Microglial Phenotype

Microglia are immunocompetent cells that are present in the retina and central nervous system, and are involved in the development maintenance and immune functions in these systems. Developing from yolk sac-primitive macrophages, they proliferate in the local tissues during the embryonic period without resorting to the production from the hematopoietic stem cells, and are critical in sustaining homeostasis and performing in disease and injury; they have morphological characteristics and distinct phenotypes according to the microenvironment. Microglia are also present in close association with resident cells in the retina where they engage in synapse formation, support normal functions, as well as immune defense. They are involved in the development of numerous neurodegenerative and ophthalmic diseases and act as diversity shields and triggers. Noncoding ribonucleic acids (ncRNAs) refer to RNA molecules synthesized from the mammalian genome, and these do not have protein-coding capacity. These ncRNAs play a role in the regulation of gene expression patterns. ncRNAs have only been recently identified as vastly significant molecules that are involved in the posttranscriptional regulation. Microglia are crucial for brain health and functions and current studies have focused on the effects caused by ncRNA on microglial types. Thus, the aim of the review was to provide an overview of the current knowledge about the regulation of microglial phenotypes by ncRNAs.

Microglia in morphine tolerance: cellular and molecular mechanisms and therapeutic potential

Morphine has a crucial role in treating both moderate to severe pain and chronic pain. However, prolonged administration of morphine can lead to tolerance of analgesia, resulting in increased doses and poor treatment of pain. Many patients, such as those with terminal cancer, require high doses of morphine for long periods. Addressing morphine tolerance can help this group of patients to escape pain, and the mechanisms behind this need to be investigated. Microglia are the key cells involved in morphine tolerance and chronic morphine administration leads to microglia activation, which in turn leads to activation of internal microglia signalling pathways and protein transcription, ultimately leading to the release of inflammatory factors. Inhibiting the activation of microglia internal signalling pathways can reduce morphine tolerance. However, the exact mechanism of how morphine acts on microglia and ultimately leads to tolerance is unknown. This article discusses the mechanisms of morphine induced microglia activation, reviews the signalling pathways within microglia and the associated therapeutic targets and possible drugs, and provides possible directions for clinical prevention or retardation of morphine induced analgesic tolerance.

CXCR3-expressing myeloid cells recruited to the hypothalamus protect against diet-induced body mass gain and metabolic dysfunction

Microgliosis plays a critical role in diet-induced hypothalamic inflammation. A few hours after a high-fat diet (HFD), hypothalamic microglia shift to an inflammatory phenotype, and prolonged fat consumption leads to the recruitment of bone marrow-derived cells to the hypothalamus. However, the transcriptional signatures and functions of these cells remain unclear. Using dual-reporter mice, this study reveals that CX3CR1-positive microglia exhibit minimal changes in response to a HFD, while significant transcriptional differences emerge between microglia and CCR2-positive recruited myeloid cells, particularly affecting chemotaxis. These recruited cells also show sex-specific transcriptional differences impacting neurodegeneration and thermogenesis. The chemokine receptor CXCR3 is emphasized for its role in chemotaxis, displaying notable differences between recruited cells and resident microglia, requiring further investigation. Central immunoneutralization of CXCL10, a ligand for CXCR3, resulted in increased body mass and decreased energy expenditure, especially in females. Systemic chemical inhibition of CXCR3 led to significant metabolic changes, including increased body mass, reduced energy expenditure, elevated blood leptin, glucose intolerance, and decreased insulin levels. This study elucidates the transcriptional differences between hypothalamic microglia and CCR2-positive recruited myeloid cells in diet-induced inflammation and identifies CXCR3-expressing recruited immune cells as protective in metabolic outcomes linked to HFD consumption, establishing a new concept in obesity-related hypothalamic inflammation.

Peripheral and central neuroplasticity in a mouse model of endometriosis

Chronic pelvic pain (CPP) is the most debilitating symptom of gynaecological disorders such as endometriosis. However, it remains unclear how sensory neurons from pelvic organs affected by endometriosis, such as the female reproductive tract, detect and transmit nociceptive events and how these signals are processed within the central nervous system (CNS). Using a previously characterized mouse model of endometriosis, we investigated whether the increased pain sensitivity occurring in endometriosis could be attributed to (i) changes in mechanosensory properties of sensory afferents innervating the reproductive tract, (ii) alterations in sensory input from reproductive organs to the spinal cord or (iii) neuroinflammation and sensitization of spinal neural circuits. Mechanosensitivity of vagina-innervating primary afferents was examined using an ex vivo single-unit extracellular recording preparation. Nociceptive signalling from the vagina to the spinal cord was quantified by phosphorylated MAP kinase ERK1/2 immunoreactivity. Immunohistochemistry was used to determine glial and neuronal circuit alterations within the spinal cord. We found that sensory afferents innervating the rostral, but not caudal portions of the mouse vagina, developed mechanical hypersensitivity in endometriosis. Nociceptive signalling from the vagina to the spinal cord was significantly enhanced in mice with endometriosis. Moreover, mice with endometriosis developed microgliosis, astrogliosis and enhanced substance P neurokinin-1 receptor immunoreactivity within the spinal cord, suggesting the development of neuroinflammation and sensitization of spinal circuitry in endometriosis. These results demonstrate endometriosis-induced neuroplasticity occurring at both peripheral and central sites of sensory afferent pathways. These findings may help to explain the altered sensitivity to pain in endometriosis and provide a novel platform for targeted pain relief treatments for this debilitating disorder.

Oxidation enhances the toxicity of polyethylene microplastics to mouse eye: Perspective from in vitro and in vivo

Microplastics (MPs) are ubiquitously dispersed in the environment, and undergoing the process of oxidation that alters their physical and chemical properties. Eyes, which directly interface with the external milieu, inevitably encounter MPs. Nonetheless, the ophthalmic toxicity of MPs towards organisms remains unclear. In this study, primary mouse corneal epithelial cells (MCECs), C57BL/6 mice, and CX3CrlGFP/+ mice were utilized to evaluate the toxicity and differences between oxidized low-density polyethylene MPs (modified-MPs) and low-density polyethylene MPs (virgin-MPs) on eyes. The results manifested that virgin-MPs and modified-MPs could be endocytosed by primary MCECs, resulting in a range of cellular damage. Furthermore, they could diminish tear secretion, increase intraocular pressure, and could be internalized into cornea and retina in mice, instigating a series of detrimental reactions. Importantly, modified-MPs exhibited heightened toxicity towards mouse eyes, seemingly due to oxidation enhances the interaction between virgin-MPs/modified-MPs and tissues/cells, and leading to the release of toxic substances increased. In conclusion, our discoveries demonstrate that oxidation exacerbates the harm of virgin-MPs to eyes, and are of great significance for evaluating the risk of MPs to ocular health.

Cedrol attenuates acute ischemic injury through inhibition of microglia-associated neuroinflammation via ERβ-NF-κB signaling pathways

Microglia-associated neuroinflammation plays essential roles in pathology of acute stroke. Cedrol, a natural compound extracted from ginger, has been shown to confer inhibitory effects on inflammation in various diseases. However, whether Cedrol suppresses neuroinflammation and protects brains from acute ischemic injury still remains unclear. In this study, we found that Cedrol inhibited microglia activation and the production of inflammatory factors in LPS-challenged microglia and the penumbra region of middle cerebral artery occlusion (MCAO) mice. We also found that Cedrol reduced the infarct size and mNSS scores and improved acute cerebral ischemia-induced behavioral outcomes, suggesting remarked neuroprotection of Cedrol. Molecular docking analysis showed that Cedrol bound to estrogen receptor β (ERβ) with moderate-strong affinity. Intriguingly, treatment with fulvestrant, an ER blocker, abolished the anti-inflammatory effects of Cedrol. Cedrol significantly reversed the LPS- and MCAO-induced increases in phosphorylation levels of IκB and NF-κB P65 in primary microglia and MCAO mice, respectively. Additionally, Cedrol was observed to rescue LPS-induced shuttling of NF-κB P65 from cytoplasm to nuclei in primary microglia, indicating inhibitory effects of Cedrol on NF-κB signaling. These results suggest microglia associated neuroinflammation may be mediated by ERβ-NF-κB signaling pathway. Together, our study reveals that Cedrol protected brain function from acute cerebral ischemia through inhibition of microglia-associated neuroinflammation via ERβ-NF-κB signaling pathways, and Cedrol may serve as an alternative option for treatment of acute stroke injury.

Activation of NF-κB/MAPK signaling and induction of apoptosis by salicylate synthase NbtS in Nocardia farcinica promotes neuroinflammation development

Nocardia farcinica can cause a rare, yet potentially fatal, central nervous system infection. NbtS protein may be a key virulence factor in N. farcinica infection of the brain. In this study, we investigated the function of the virulence-associated factor NbtS in microglial cells in vitro and in infected mice in vivo. We explored the interactions between NbtS and microglial cells (BV2 and human microglial clone 3), revealing that NbtS activates the toll-like receptor 4-dependent MyD88-IRAK4-IRAK1 and MAPK/nuclear factor kappa B (NF-κB) pathways, significantly enhancing pro-inflammatory responses as indicated by increased levels of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), as measured by ELISA and quantitative PCR. Apoptosis was elevated in these cells, as shown by increased expression of Bax and caspase-3 and decreased Bcl-2 levels. The terminal deoxynucleotidyl transferase dUTP nick end labeling assay also confirmed the occurrence of apoptosis. In vivo, mice infected with an RS03155-deficient strain of N. farcinica exhibited higher survival rates and reduced brain inflammation, suggesting a pivotal role for the NbtS protein in the pathogenesis of Nocardia. Conservation of the RS03155 gene across Nocardia spp. was verified by PCR, and the immunogenic potential of NbtS was confirmed by Western blot analysis using sera from infected mice. These findings suggest that targeting NbtS may offer a novel therapeutic strategy against Nocardia infection.

IMPORTANCE

The study presented in this article delves into the molecular underpinnings of Nocardia farcinica-induced neuroinflammation. By focusing on the salicylate synthase gene, RS03155, and its encoded protein, NbtS, we uncover a pivotal virulence factor that triggers a cascade of immunological responses leading to apoptosis in microglial cells. This research not only enhances our comprehension of the pathogenesis of Nocardia infections but also provides a potential therapeutic target. Given the rising importance of understanding host-microbe interactions within the context of the central nervous system, especially in immunocompromised individuals, the findings are of significant relevance to the field of microbiology and could inform future diagnostic and treatment modalities for Nocardia-associated neurological disorders. Our work emphasizes the need for continued research into the intricate mechanisms of microbial pathogenesis and the development of novel strategies to combat life-threatening infections.

The Role of Immune Cells and Signaling Pathways in Diabetic Eye Disease: A Comprehensive Review

Diabetic eye disease (DED) encompasses a range of ocular complications arising from diabetes mellitus, including diabetic retinopathy, diabetic macular edema, diabetic keratopathy, diabetic cataract, and glaucoma. These conditions are leading causes of visual impairments and blindness, especially among working-age adults. Despite advancements in our understanding of DED, its underlying pathophysiological mechanisms remain incompletely understood. Chronic hyperglycemia, oxidative stress, inflammation, and neurodegeneration play central roles in the development and progression of DED, with immune-mediated processes increasingly recognized as key contributors. This review provides a comprehensive examination of the complex interactions between immune cells, inflammatory mediators, and signaling pathways implicated in the pathogenesis of DED. By delving in current research, this review aims to identify potential therapeutic targets, suggesting directions of research for future studies to address the immunopathological aspects of DED.

Transcriptional profiling in microglia across physiological and pathological states identifies a transcriptional module associated with neurodegeneration

Microglia are the resident immune cells of the central nervous system and are involved in brain development, homeostasis, and disease. New imaging and genomics technologies are revealing microglial complexity across developmental and functional states, brain regions, and diseases. We curated a set of publicly available gene expression datasets from human microglia spanning disease and health to identify sets of genes reflecting physiological and pathological microglial states. We also integrated multiple human microglial single-cell RNA-seq datasets in Alzheimer's disease (AD), multiple sclerosis (MS), and Parkinson's disease, and identified a distinct microglial transcriptional signature shared across diseases. Analysis of germ-line DNA identified genes with variants associated with AD and MS that are overrepresented in microglial gene sets, including the disease-associated transcriptional signature. This work points to genes that are dysregulated in disease states and provides a resource for the analysis of diseases in which microglia are implicated by genetic evidence.

rTMS improves dysphagia by inhibiting NLRP3 inflammasome activation and caspase-1 dependent pyroptosis in PD mice

High incidence, severe consequences, unclear mechanism, and poor treatment effect happened in Parkinson's disease-related dysphagia. Repetitive transcranial magnetic stimulation is an effective treatment for dysphagia in Parkinson's disease. However, the therapeutic effect and underlying mechanism of repetitive transcranial magnetic stimulation for dysphagia in Parkinson's disease are still unknown. Neuroinflammation has been proven to be associated with dysphagia in Parkinson's disease, and NLRP3 inflammasome activation and pyroptosis are common neuroinflammatory processes. Therefore, we compared swallowing quality, NLRP3 inflammasome activation, and caspase-1 dependent pyroptosis among NS control, repetitive transcranial magnetic stimulation control, sham repetitive transcranial magnetic stimulation control, and L-Dopa control mice by tongue muscle tone detection, immunohistochemistry, immunofluorescence, western blotting, co-immunoprecipitation, and quantitative PCR. The results showed that NLRP3 inflammasome activation and caspase-1-dependent pyroptosis were involved in dysphagia in MPTP-induced Parkinson's disease mice model. Repetitive transcranial magnetic stimulation and L-dopa inhibited the above two pathways to alleviate dopaminergic neuronal damage and improve the quality of dysphagia. Repetitive transcranial magnetic stimulation (1 Hz, 1 time/3 days, 6 weeks) had the same effect on dysphagia as L-Dopa treatment (25 mg/kg/day, 6 weeks). Finally, we conclude that repetitive transcranial magnetic stimulation will be the preferred option for the treatment of dysphagia in Parkinson's disease in certain conditions such as motor complications secondary to L-Dopa and L-Dopa non-response dysphagia.

Single-cell multiomics analysis reveals cell/tissue-specific associations in bipolar disorder

This study investigates the cellular origin and tissue heterogeneity in bipolar disorder (BD) by integrating multiomics data. Four distinct datasets were employed, including single-cell RNA sequencing (scRNA-seq) data (embryonic and fetal brain, n = 8, 1,266 cells), BD Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) data (adult brain, n = 210), BD bulk RNA-seq data (adult brain, n = 314), and BD genome-wide association study (GWAS) summary data (n = 413,466). The integration of scRNA-seq data with multiomics data relevant to BD was accomplished using the single-cell disease relevance score (scDRS) algorithm. We have identified a novel brain cell cluster named ADCY1, which exhibits distinct genetic characteristics. From a high-resolution genetic perspective, glial cells emerge as the primary cytopathology associated with BD. Specifically, astrocytes were significantly related to BD at the RNA-seq level, while microglia showed a strong association with BD across multiple panels, including the transcriptome-wide association study (TWAS), ATAC-seq, and RNA-seq. Additionally, oligodendrocyte precursor cells displayed a significant association with BD in both ATAC-seq and RNA-seq panel. Notably, our investigation of brain regions affected by BD revealed significant associations between BD and all three types of glial cells in the dorsolateral prefrontal cortex (DLPFC). Through comprehensive analyses, we identified several BD-associated genes, including CRMP1, SYT4, UCHL1, and ZBTB18. In conclusion, our findings suggest that glial cells, particularly in specific brain regions such as the DLPFC, may play a significant role in the pathogenesis of BD. The integration of multiomics data has provided valuable insights into the etiology of BD, shedding light on potential mechanisms underlying this complex psychiatric disorder.

The anti-inflammatory effects of itaconate and its derivatives in neurological disorders

Almost 16 % of the global population is affected by neurological disorders, including neurodegenerative and cerebral neuroimmune diseases, triggered by acute or chronic inflammation. Neuroinflammation is recognized as a common pathogenic mechanism in a wide array of neurological conditions including Alzheimer's disease, Parkinson's disease, postoperative cognitive dysfunction, stroke, traumatic brain injury, and multiple sclerosis. Inflammatory process in the central nervous system (CNS) can lead to neuronal damage and neuronal apoptosis, consequently exacerbating these diseases. Itaconate, an immunomodulatory metabolite from the tricarboxylic acid cycle, suppresses neuroinflammation and modulates the CNS immune response. Emerging human studies suggest that itaconate levels in plasma and cerebrospinal fluid may serve as biomarkers associated with inflammatory responses in neurological disorders. Preclinical studies have shown that itaconate and its highly cell-permeable derivatives are promising candidates for preventing and treating neuroinflammation-related neurological disorders. The underlying mechanism may involve the regulation of immune cells in the CNS and neuroinflammation-related signaling pathways and molecules including Nrf2/KEAP1 signaling pathway, reactive oxygen species, and NLRP3 inflammasome. Here, we introduce the metabolism and function of itaconate and the synthesis and development of its derivatives. We summarize the potential impact and therapeutic potential of itaconate and its derivatives on brain immune cells and the associated signaling pathways and molecules, based on preclinical evidence via various neurological disorder models. We also discuss the challenges and potential solutions for clinical translation to promote further research on itaconate and its derivatives for neuroinflammation-related neurological disorders.

The impact of Nrf2 knockout on the neuroprotective effects of dexmedetomidine in a mice model of cognitive impairment

The nuclear factor erythroid 2-related factor 2 (Nrf2) signalling pathway represents a crucial intrinsic protective system against oxidative stress and inflammation and plays a significant role in various neurological disorders. However, the effect of Nrf2 signalling on the regulation of cognitive impairment remains unknown. Dexmedetomidine (DEX) has neuroprotective effects and can ameliorate lipopolysaccharide (LPS)-induced cognitive dysfunction. Our objective was to observe whether Nrf2 knockout influences the efficacy of DEX in improving cognitive impairment and to attempt to understand its underlying mechanisms. An LPS-induced cognitive dysfunction model in wild-type and Nrf2 knockout mice (Institute of Cancer Research background; male; 8-12 weeks) was used to observe the impact of DEX on cognitive dysfunction. LPS was intraperitoneally injected, followed by novel object recognition and morris water maze experiments 24 h later. Hippocampal tissues were collected for histopathological and molecular analyses. Our research findings suggest that DEX enhances the expression of NQO1, HO-1, PSD95, and SYP proteins in hippocampal tissue, inhibits microglial proliferation, reduces pro-inflammatory cytokines IL-1β and TNF-ɑ, increases anti-inflammatory cytokine IL-10, and improves dendritic spine density, thereby alleviating cognitive dysfunction induced by LPS. However, the knockout of the Nrf2 gene negated the aforementioned effects of DEX. In conclusion, DEX alleviates cognitive deficits induced by LPS through mechanisms of anti-oxidative stress and anti-inflammation, as well as by increasing synaptic protein expression and dendritic spine density. However, the knockout of the Nrf2 gene reversed the effects of DEX. The Nrf2 signaling pathway plays a crucial role in the mitigation of LPS-induced cognitive impairment by DEX.

Coffee, antioxidants, and brain inflammation

Coffee is the most popular beverage in the world and, aside from tea and water, the most often consumed caffeine-containing beverage. Because of its high caffeine concentration, it is typically classified as a stimulant. There are other bioactive ingredients in coffee besides caffeine. The coffee beverage is a blend of several bioactive substances, including diterpenes (cafestol and kahweol), alkaloids (caffeine and trigonelline), and polyphenols (particularly chlorogenic acids in green beans and caffeic acid in roasted coffee beans). Caffeine has also been linked to additional beneficial benefits such as antioxidant and anti-inflammatory properties, which change cellular redox and inflammatory status in a dose-dependent manner. Pyrocatechol, a constituent of roasted coffee that is created when chlorogenic acid is thermally broken down, has anti-inflammatory properties as well. It is postulated that coffee consumption reduces neuroinflammation, which is intimately linked to the onset of neurodegenerative disorders like Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). This review provides an overview of the most recent studies regarding coffee's possible benefits in preventing brain inflammation and neurodegenerative disorders.

Functional and morphological adaptation of medial prefrontal corticotropin releasing factor receptor 1-expressing neurons in male mice following chronic ethanol exposure

Chronic ethanol dependence and withdrawal activate corticotropin releasing factor (CRF)-containing GABAergic neurons in the medial prefrontal cortex (mPFC), which tightly regulate glutamatergic pyramidal neurons. Using male CRF1:GFP reporter mice, we recently reported that CRF1-expressing (mPFCCRF1+) neurons predominantly comprise mPFC prelimbic layer 2/3 pyramidal neurons, undergo profound adaptations following chronic ethanol exposure, and regulate anxiety and conditioned rewarding effects of ethanol. To explore the effects of acute and chronic ethanol exposure on glutamate transmission, the impact of chronic alcohol on spine density and morphology, as well as persistent changes in dendritic-related gene expression, we employed whole-cell patch-clamp electrophysiology, diOlistic labeling for dendritic spine analysis, and dendritic gene expression analysis to further characterize mPFCCRF1+ and mPFCCRF1- prelimbic layer 2/3 pyramidal neurons. We found increased glutamate release in mPFCCRF1+ neurons with ethanol dependence, which recovered following withdrawal. In contrast, we did not observe significant changes in glutamate transmission in neighboring mPFCCRF1- neurons. Acute application of 44 mM ethanol significantly reduced glutamate release onto mPFCCRF1+ neurons, which was observed across all treatment groups. However, this sensitivity to acute ethanol was only evident in mPFCCRF1- neurons during withdrawal. In line with alterations in glutamate transmission, we observed a decrease in total spine density in mPFCCRF1+ neurons during dependence, which recovered following withdrawal, while again no changes were observed in mPFCCRF- neurons. Given the observed decreases in mPFCCRF1+ stubby spines during withdrawal, we then identified persistent changes at the dendritic gene expression level in mPFCCRF1+ neurons following withdrawal that may underlie these structural adaptations. Together, these findings highlight the varying responses of mPFCCRF1+ and mPFCCRF1- cell-types to acute and chronic ethanol exposure, as well as withdrawal, revealing specific functional, morphological, and molecular adaptations that may underlie vulnerability to ethanol and the lasting effects of ethanol dependence.

Anatomical location of injected microglia in different activation states and time course of injury determines survival of retinal ganglion cells after optic nerve crush

Background: Activated microglia release harmful substances to retinal ganglion cells (RGCs), but may also benefit by removing cellular debris and secreting neurotrophic factors. These paradoxical roles remain controversial because the nature and time-course of the injury that defines their role is unknown. The aim of this study was to determine if pharmacological manipulation of microglia to acquire a pro-inflammatory or pro-survival phenotype will exacerbate or enhance neuronal survival after injury.Material and methods: Treated HAP I (highly aggressively proliferating immortalized) microglia were injected into the vitreous or tail vein (T V) of female Sprague-Dawley rats. Retinas were examined at 4-14 days following optic nerve crush (ONC) and the number of surviving RGCs was determined.Results: Injection of untreated HAP I cells resulted in the greater loss of RGCs early after ONC when injected into the vitreous and later after ONC when injected into the T V. LP S activated HAP I cells injected into the vitreous resulted in greater RGC loss with and without injury. When injected into the T V with ONC there was no loss of RGCs 4 days after ONC but greater loss afterwards. Minocycline treated HAP I cells injected into the vitreous resulted in greater RGC survival than untreated HAP I cells. However, when injected into the T V with ONC there was greater loss of RGCs. These results suggest that optic nerve signals attract extrinsic microglia to the retina, resulting in a proinflammatory response.Conclusion: Neuroprotection or cytotoxicity of microglia depends on the type of activation, time course of the injury, and if they act on the axon or cell body.

cGAS/STING signaling pathway-mediated microglial activation in the PFC underlies chronic ethanol exposure-induced anxiety-like behaviors in mice

Chronic ethanol consumption is a prevalent condition in contemporary society and exacerbates anxiety symptoms in healthy individuals. The activation of microglia, leading to neuroinflammatory responses, may serve as a significant precipitating factor; however, the precise molecular mechanisms underlying this phenomenon remain elusive. In this study, we initially confirmed that chronic ethanol exposure (CEE) induces anxiety-like behaviors in mice through open field test and elevated plus maze test. The cGAS/STING signaling pathway has been confirmed to exhibits a significant association with inflammatory signaling responses in both peripheral and central systems. Western blot analysis confirmed alterations in the cGAS/STING signaling pathway during CEE, including the upregulation of p-TBK1 and p-IRF3 proteins. Moreover, we observed microglial activation in the prefrontal cortex (PFC) of CEE mice, characterized by significant alterations in branching morphology and an increase in cell body size. Additionally, we observed that administration of CEE resulted in mitochondrial dysfunction within the PFC of mice, accompanied by a significant elevation in cytosolic mitochondrial DNA (mtDNA) levels. Furthermore, our findings revealed that the inhibition of STING by H-151 effectively alleviated anxiety-like behavior and suppressed microglial activation induced by CEE. Our study unveiled a significant association between anxiety-like behavior, microglial activation, inflammation, and mitochondria dysfunction during CEE.

TMEM119-positive microglia were increased in the brains of patients with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that has been reported to be affected by inflammatory cells, such as microglia and macrophages, through the concept of non-cell autonomous neuronal death. Resident microglia in the human brain and monocyte-derived macrophages (MoDM) infiltrating in tissues are difficult to distinguish. Therefore, the effects of microglia and MoDMs in ALS remain poorly understood. This study aimed to investigate the role of resident microglia and MoDMs in the pathogenesis of ALS using postmortem brain and spinal cord samples. The samples used for immunohistochemical analysis included 11 cases of sporadic ALS and 11 age-matched controls. We stained the cells with TMEM119 to detect resident microglia and CCR2 to detect MoDMs. In ALS cases, TMEM119-immunopositive resident microglia were abundant in the motor cortex and subcortical white matter (SWM) of the motor area, whereas CCR2-immunopositive MoDM was similar to control cases. In addition, the mean density of CD68-immunopositive cells in the SWM significantly correlated with the mean density of pTDP-43-positive GCIs. These results suggest that resident microglial activation plays an important role in the cerebral pathogenesis of ALS and may provide novel therapeutic strategies to target excessive activation of resident microglia in ALS.

Allopregnanolone and its antagonist modulate neuroinflammation and neurological impairment

Neuroinflammation accompanies several brain disorders, either as a secondary consequence or as a primary cause and may contribute importantly to disease pathogenesis. Neurosteroids which act as Positive Steroid Allosteric GABA-A receptor Modulators (Steroid-PAM) appear to modulate neuroinflammation and their levels in the brain may vary because of increased or decreased local production or import from the systemic circulation. The increased synthesis of steroid-PAMs is possibly due to increased expression of the mitochondrial cholesterol transporting protein (TSPO) in neuroinflammatory tissue, and reduced production may be due to changes in the enzymatic activity. Microglia and astrocytes play an important role in neuroinflammation, and their production of inflammatory mediators can be both activated and inhibited by steroid-PAMs and GABA. What is surprising is the finding that both allopregnanolone, a steroid-PAM, and golexanolone, a novel GABA-A receptor modulating steroid antagonist (GAMSA), can inhibit microglia and astrocyte activation and normalize their function. This review focuses on the role of steroid-PAMs in neuroinflammation and their importance in new therapeutic approaches to CNS and liver disease.

Developmental Programming of the Fetal Immune System by Maternal Western-Style Diet: Mechanisms and Implications for Disease Pathways in the Offspring

Maternal obesity and over/undernutrition can have a long-lasting impact on offspring health during critical periods in the first 1000 days of life. Children born to mothers with obesity have reduced immune responses to stimuli which increase susceptibility to infections. Recently, maternal western-style diets (WSDs), high in fat and simple sugars, have been associated with skewing neonatal immune cell development, and recent evidence suggests that dysregulation of innate immunity in early life has long-term consequences on metabolic diseases and behavioral disorders in later life. Several factors contribute to abnormal innate immune tolerance or trained immunity, including changes in gut microbiota, metabolites, and epigenetic modifications. Critical knowledge gaps remain regarding the mechanisms whereby these factors impact fetal and postnatal immune cell development, especially in precursor stem cells in bone marrow and fetal liver. Components of the maternal microbiota that are transferred from mothers consuming a WSD to their offspring are understudied and identifying cause and effect on neonatal innate and adaptive immune development needs to be refined. Tools including single-cell RNA-sequencing, epigenetic analysis, and spatial location of specific immune cells in liver and bone marrow are critical for understanding immune system programming. Considering the vital role immune function plays in offspring health, it will be important to understand how maternal diets can control developmental programming of innate and adaptive immunity.

B355252 Suppresses LPS-Induced Neuroinflammation in the Mouse Brain

B355252 is a small molecular compound known for potentiating neural growth factor and protecting against neuronal cell death induced by glutamate in vitro and cerebral ischemia in vivo. However, its other biological functions remain unclear. This study aims to investigate whether B355252 suppresses neuroinflammatory responses and cell death in the brain. C57BL/6j mice were intraperitoneally injected with a single dosage of lipopolysaccharide (LPS, 1 mg/kg) to induce inflammation. B355252 (1 mg/kg) intervention was started two days prior to the LPS injection. The animal behavioral changes were assessed pre- and post-LPS injections. The animal brains were harvested at 4 and 24 h post-LPS injection, and histological, biochemical, and cytokine array outcomes were examined. Results showed that B355252 improved LPS-induced behavioral deterioration, mitigated brain tissue damage, and suppressed the activation of microglial and astrocytes. Furthermore, B355252 reduced the protein levels of key pyroptotic markers TLR4, NLRP3, and caspase-1 and inhibited the LPS-induced increases in IL-1β, IL-18, and cytokines. In conclusion, B355252 demonstrates a potent anti-neuroinflammatory effect in vivo, suggesting that its potential therapeutic value warrants further investigation.

Basic Science of Neuroinflammation and Involvement of the Inflammatory Response in Disorders of the Nervous System

Neuroinflammation is a key immune response observed in many neurologic diseases. Although an appropriate immune response can be beneficial, aberrant activation of this response recruits excessive proinflammatory cells to cause damage. Because the central nervous system is separated from the periphery by the blood-brain barrier (BBB) that creates an immune-privileged site, it has its own unique immune cells and immune response. Moreover, neuroinflammation can compromise the BBB causing an influx of peripheral immune cells and factors. Recent advances have brought a deeper understanding of neuroinflammation that can be leveraged to develop more potent therapies and improve patient selection.

Oxidative stress involvement in the molecular pathogenesis and progression of multiple sclerosis: a literature review

Multiple sclerosis (MS) is an autoimmune debilitating disease of the central nervous system caused by a mosaic of interactions between genetic predisposition and environmental factors. The pathological hallmarks of MS are chronic inflammation, demyelination, and neurodegeneration. Oxidative stress, a state of imbalance between the production of reactive species and antioxidant defense mechanisms, is considered one of the key contributors in the pathophysiology of MS. This review is a comprehensive overview of the cellular and molecular mechanisms by which oxidant species contribute to the initiation and progression of MS including mitochondrial dysfunction, disruption of various signaling pathways, and autoimmune response activation. The detrimental effects of oxidative stress on neurons, oligodendrocytes, and astrocytes, as well as the role of oxidants in promoting and perpetuating inflammation, demyelination, and axonal damage, are discussed. Finally, this review also points out the therapeutic potential of various synthetic antioxidants that must be evaluated in clinical trials in patients with MS.

Perivascular macrophages in cerebrovascular diseases

Cerebrovascular diseases are a major cause of stroke and dementia, both requiring long-term care. These diseases involve multiple pathophysiologies, with mitochondrial dysfunction being a crucial contributor to the initiation of inflammation, apoptosis, and oxidative stress, resulting in injuries to neurovascular units that include neuronal cell death, endothelial cell death, glial activation, and blood-brain barrier disruption. To maintain brain homeostasis against these pathogenic conditions, brain immune cells, including border-associated macrophages and microglia, play significant roles as brain innate immunity cells in the pathophysiology of cerebrovascular injury. Although microglia have long been recognized as significant contributors to neuroinflammation, attention has recently shifted to border-associated macrophages, such as perivascular macrophages (PVMs), which have been studied based on their crucial roles in the brain. These cells are strategically positioned around the walls of brain vessels, where they mainly perform critical functions, such as perivascular drainage, cerebrovascular flexibility, phagocytic activity, antigen presentation, activation of inflammatory responses, and preservation of blood-brain barrier integrity. Although PVMs act as scavenger and surveillant cells under normal conditions, these cells exert harmful effects under pathological conditions. PVMs detect mitochondrial dysfunction in injured cells and implement pathological changes to regulate brain homeostasis. Therefore, PVMs are promising as they play a significant role in mitochondrial dysfunction and, in turn, disrupt the homeostatic condition. Herein, we summarize the significant roles of PVMs in cerebrovascular diseases, especially ischemic and hemorrhagic stroke and dementia, mainly in correlation with inflammation. A better understanding of the biology and pathobiology of PVMs may lead to new insights on and therapeutic strategies for cerebrovascular diseases.

Versatile strategies for adult neurogenesis: avenues to repair the injured brain

Brain injuries due to trauma or stroke are major causes of adult death and disability. Unfortunately, few interventions are effective for post-injury repair of brain tissue. After a long debate on whether endogenous neurogenesis actually happens in the adult human brain, there is now substantial evidence to support its occurrence. Although neurogenesis is usually significantly stimulated by injury, the reparative potential of endogenous differentiation from neural stem/progenitor cells is usually insufficient. Alternatively, exogenous stem cell transplantation has shown promising results in animal models, but limitations such as poor long-term survival and inefficient neuronal differentiation make it still challenging for clinical use. Recently, a high focus was placed on glia-to-neuron conversion under single-factor regulation. Despite some inspiring results, the validity of this strategy is still controversial. In this review, we summarize historical findings and recent advances on neurogenesis strategies for neurorepair after brain injury. We also discuss their advantages and drawbacks, as to provide a comprehensive account of their potentials for further studies.

The Interplay between Glioblastoma Cells and Tumor Microenvironment: New Perspectives for Early Diagnosis and Targeted Cancer Therapy

Glioblastoma multiforme (GBM) stands out as the most tremendous brain tumor, constituting 60% of primary brain cancers, accompanied by dismal survival rates. Despite advancements in research, therapeutic options remain limited to chemotherapy and surgery. GBM molecular heterogeneity, the intricate interaction with the tumor microenvironment (TME), and non-selective treatments contribute to the neoplastic relapse. Diagnostic challenges arise from GBM advanced-stage detection, necessitating the exploration of novel biomarkers for early diagnosis. Using data from the literature and a bioinformatic tool, the current manuscript delineates the molecular interplay between human GBM, astrocytes, and myeloid cells, underscoring selected protein pathways belonging to astroglia and myeloid lineage, which can be considered for targeted therapies. Moreover, the pivotal role of extracellular vesicles (EVs) in orchestrating a favorable microenvironment for cancer progression is highlighted, suggesting their utility in identifying biomarkers for GBM early diagnosis.

Melatonin Enhanced Microglia M2 Polarization in Rat Model of Neuro-inflammation Via Regulating ER Stress/PPARδ/SIRT1 Signaling Axis

Neuro-inflammation involves distinct alterations of microglial phenotypes, containing nocuous pro-inflammatory M1-phenotype and neuroprotective anti-inflammatory M-phenotype. Currently, there is no effective treatment for modulating such alterations. M1/M2 marker of primary microglia influenced by Melatonin were detected via qPCR. Functional activities were explored by western blotting, luciferase activity, EMSA, and ChIP assay. Structure interaction was assessed by molecular docking and LIGPLOT analysis. ER-stress detection was examined by ultrastructure TEM, calapin activity, and ERSE assay. The functional neurobehavioral evaluations were used for investigation of Melatonin on the neuroinflammation in vivo. Melatonin had targeted on Peroxisome Proliferator Activated Receptor Delta (PPARδ) activity, boosted LPS-stimulated alterations in polarization from the M1 to the M2 phenotype, and thereby inhibited NFκB-IKKβ activation in primary microglia. The PPARδ agonist L-165,041 or over-expression of PPARδ plasmid (ov-PPARδ) showed similar results. Molecular docking screening, dynamic simulation approaches, and biological studies of Melatonin showed that the activated site was located at PPARδ (phospho-Thr256-PPARδ). Activated microglia had lowered PPARδ activity as well as the downstream SIRT1 formation via enhancing ER-stress. Melatonin, PPARδ agonist and ov-PPARδ all effectively reversed the above-mentioned effects. Melatonin blocked ER-stress by regulating calapin activity and expression in LPS-activated microglia. Additionally, Melatonin or L-165,041 ameliorated the neurobehavioral deficits in LPS-aggravated neuroinflammatory mice through blocking microglia activities, and also promoted phenotype changes to M2-predominant microglia. Melatonin suppressed neuro-inflammation in vitro and in vivo by tuning microglial activation through the ER-stress-dependent PPARδ/SIRT1 signaling cascade. This treatment strategy is an encouraging pharmacological approach for the remedy of neuro-inflammation associated disorders.