Microglia in Central Nervous System Inflammation and Multiple Sclerosis Pathology

Piezo1 in microglial cells: Implications for neuroinflammation and tumorigenesis

Microglia, the central nervous system (CNS) resident immune cells, are pivotal in regulating neurodevelopment, maintaining neural homeostasis, and mediating neuroinflammatory responses. Recent research has highlighted the importance of mechanotransduction, the process by which cells convert mechanical stimuli into biochemical signals, in regulating microglial activity. Among the various mechanosensitive channels, Piezo1 has emerged as a key player in microglia, influencing their behavior under both physiological and pathological conditions. This review focuses on the expression and role of Piezo1 in microglial cells, particularly in the context of neuroinflammation and tumorigenesis. We explore how Piezo1 mediates microglial responses to mechanical changes within the CNS, such as alterations in tissue stiffness and fluid shear stress, which are common in conditions like multiple sclerosis, Alzheimer's disease, cerebral ischemia, and gliomas. The review also discusses the potential of targeting Piezo1 for therapeutic intervention, given its involvement in the modulation of microglial activity and its impact on disease progression. This review integrates findings from recent studies to provide a comprehensive overview of Piezo1's mechanistic pathways in microglial function. These insights illuminate new possibilities for developing targeted therapies addressing CNS disorders with neuroinflammation and pathological tissue mechanics.

Revealing the underlying mechanisms of nanoplastics induces neuroinflammation: From transcriptomic analysis to in vivo and in vitro validation

With the widespread use of plastic products globally, the harmful impacts of nanoplastics (NPs) on human health are not to be underestimated. Although the NPs-induced neurotoxicity has already been affirmed, the related mechanisms are still not fully understood. Therefore, this study aims to reveal the underlying mechanisms of NPs-induced neurotoxicity. After mice were randomly divided into the control, low-dose polystyrene nanoplastics (PS-NPs-L, 10 mg/kg), middle-dose PS-NPs (PS-NPs-M, 20 mg/kg), and high-dose PS-NPs (PS-NPs-H, 50 mg/kg) groups, we discovered PS-NPs with a mean diameter of approximately 100 nm were accumulated in the brain of mice, induced anxiety-like behaviors and cognitive dysfunction, caused pathological injuries to the mice's prefrontal cortex tissue, and elevated the Iba1 and GFAP expression in the mice's prefrontal cortex tissue. After BV-2 cells were randomly divided into the control, PS-NPs-L (25 μg/mL), PS-NPs-M (50 μg/mL), and PS-NPs-H (75 μg/mL) groups, we discovered PS-NPs inhibited cell viability, arrested the cell cycle in the G2 phase, and enhanced apoptosis and the ROS level of BV-2 cells. The transcriptomic analysis based on mice's prefrontal cortex tissues screened four shared DEGs, namely Pbx3, Ecell, Crb1, and Ngb. The differentially expressed genes were enriched in multiple pathways, especially the positive regulation of NIK/NF-kappaB signaling. In vitro, PS-NPs also increased the mean fluorescence intensity of p65, TNF-α, and IL-1β of BV-2 cells. In vivo and in vitro, PS-NPs up-regulated the mRNA and protein expression levels of NF-κB, TNF-α, and IL-1β. Our studies affirmed that PS-NPs induced neuroinflammation by activating the NF-κB signaling to promote the release of TNF-α and IL-1β based on transcriptomic analysis as well as in vivo and in vitro validation.

GIV/Girdin Modulation of Microglial Activation in Ischemic Stroke: Impact of FTO-Mediated m6A Modification

Ischemic stroke (IS) is one of the most common causes of death in the world. The lack of effective pharmacological treatments for IS was primarily due to a lack of understanding of its pathogenesis. Gα-Interacting vesicle-associated protein (GIV/Girdin) is a multi-modular signal transducer and guanine nucleotide exchange factor that controls important signaling downstream of multiple receptors. The purpose of this study was to investigate the role of GIV in IS. In the present study, we found that GIV is highly expressed in the central nervous system (CNS). GIV protein level was decreased, while GIV transcript level was increased in the middle cerebral artery occlusion reperfusion (MCAO/R) mice model. Additionally, GIV was insensitive lipopolysaccharide (LPS) exposure. Interestingly, we found that GIV overexpression dramatically restrained microglial activation, inflammatory response, and M1 polarization in BV-2 microglia induced by oxygen-glucose deprivation and reoxygenation (OGD/R). On the contrary, GIV knockdown had the opposite impact. Mechanistically, we found that GIV activated the Wnt/β-catenin signaling pathway by interacting with DVL2 (disheveled segment polarity protein 2). Notably, m6A demethylase fat mass and obesity-associated protein (FTO) decreased the N6-methyladenosine (m6A) modification-mediated increase of GIV expression and attenuated the inflammatory response in BV-2 stimulated by OGD/R. Taken together, our results demonstrate that GIV inhibited the inflammatory response via activating the Wnt/β-catenin signaling pathway which expression regulated in an FTO-mediated m6A modification in IS. These results broaden our understanding of the role of the FTO-GIV axis in IS development.

Evaluating the Evidence for Neuroprotective and Axonal Regenerative Activities of Different Inflammatory Cell Types After Optic Nerve Injury

The optic nerve contains retinal ganglion cell (RGC) axons and functions to transmit visual stimuli to the brain. Injury to the optic nerve from ischemia, trauma, or disease leads to retrograde axonal degeneration and subsequent RGC dysfunction and death, causing irreversible vision loss. Inflammatory responses to neurological damage and axonal injuries in the central nervous system (CNS) are typically harmful to neurons and prevent recovery. However, recent evidence indicates that certain inflammatory cell types and signaling pathways are protective after optic nerve injury and promote RGC survival and axonal regeneration. The objective of this review is to examine the evidence for diverse effects of inflammatory cell types on the retina and optic nerve after injury. Additionally, we highlight promising avenues for further research.

A Novel H2S Donor Alleviates Neuroinflammation and Seizures by Inhibiting the C3-C3aR Pathway

Both astrocytes and microglia are activated in the epileptic brain. There is an interaction between them through the complement 3 (C3)-C3a receptor (C3aR) pathway, which plays a detrimental role in seizures. Our self-developed novel H2S donor has been found to have anti-seizure effects. However, its mechanism remains to be explored. In the present study, we showed that the novel H2S donor can inhibit the activation of astrocytes and microglia and their interaction through C3-C3aR signaling, which contributed to alleviating microglial neuroinflammation and seizures. In LPS-treated astrocytes and pilocarpine-induced epileptic mice, the H2S donor reduced C3 production in astrocytes and regulated the expression of inflammatory cytokines IL-1β and IL-10 in microglia. The H2S donor also reduced the EEG amplitude of hippocampal epileptic waves and relieved seizures in epileptic mice. These effects of the H2S donor can be reversed by intranasal C3 treatment and mimicked by a C3aR antagonist. These findings provide a novel mechanism underlying the anti-seizure effects of the H2S donor. Therefore, the H2S donor has the potential to be used as a candidate for antiepileptic drugs.

Irisin restrains neuroinflammation in mouse experimental autoimmune encephalomyelitis via regulating microglia activation

Introduction

Multiple sclerosis is a chronic autoimmune demyelinating disorder predominantly affecting the white matter of the central nervous system, with experimental autoimmune encephalomyelitis (EAE) serving as its classical animal model. Irisin, a glycosylated protein derived from the proteolytic cleavage of fibronectin type III domain-containing protein 5, plays a significant role in metabolic regulation and inflammatory modulation within the organism.

Methods

In this study, we systematically investigated the therapeutic effects and underlying mechanism of Irisin on EAE and BV2 microglial cells through comprehensive methodologies including quantitative real-time polymerase chain reaction, immunofluorescence staining and western blot.

Results

Irisin exerts neuroprotective effects in EAE mice, significantly ameliorating both clinical and pathological manifestations of the disease. Mechanistically, Irisin attenuated inflammatory response and reduced the number of microglia through NF-κBp65 signaling pathway.

Conclusion

In conclusion, these results collectively suggest that Irisin alleviates EAE progression by suppressing microglia activation via the NF-κBp65 pathway, highlighting its potential as a promising therapeutic target for multiple sclerosis treatment.

The potential effectiveness of probiotics in reducing multiple sclerosis progression in preclinical and clinical studies: A worldwide systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Multiple Sclerosis (MS) is an immune-mediated disease characterized by nerve cell inflammation and demyelination. The effectiveness of probiotics in reducing inflammatory damage in MS. Therefore, the aim of this systematic review and meta-analysis was the potential effectiveness of probiotics in reducing Multiple Sclerosis progression in preclinical and clinical studies.

METHODS

PubMed, Scopus, Cochrane, and Google Scholar databases were searched using multiple relevant keywords, and screening was carried out based on the inclusion/exclusion criteria from January 2004 to August 16, 2024.

RESULTS

Based on our criteria, 269 papers were obtained, and after omission of unsuitable articles, 23 full-text articles consisting of 17 animal studies and six human models were selected. It was concluded that in an experimental autoimmune encephalomyelitis (EAE) animal model, probiotics such as Bifidobacterium, Prevotella, and Lactobacillus can decrease the T helper 1 (Th1)/Th17 ratio while inducing interferon gamma (IFN-γ) and interleukin (IL)-17 levels. In all cases, probiotics can modulate immune cells and cytokines and consequently decrease EAE signs and symptoms. In all human studies, single or multiple probiotics decreased the severity of disease and changed the gut microbiota population.

CONCLUSION

Our results showed that probiotics can control the development of MS by reducing inflammatory conditions, and may have beneficial effects in the prevention and treatment of MS.

Targeting microglia-Th17 feed-forward loop to suppress autoimmune neuroinflammation

Microglia and Th17 cells are the major immunopathogenic cells in multiple sclerosis and its animal model of immune aspects, experimental autoimmune encephalomyelitis (EAE). While studies have highlighted the distinct roles of microglia and Th17 cells in EAE, it remains unclear whether microglia, as potential professional antigen-presenting cells, activate and stabilize the effector program of EAE-pathogenic Th17 cells in vivo; and if so, whether the Th17 could in turn reinforce the active state of the microglia. Our data demonstrate in an array of mouse models, including active/passive-EAE and transgenic mice, a microglia-Th17 feed-forward activation loop drives EAE disease progression through a mechanism dependent on both MHC-II, proinflammatory cytokines, inflammatory chemokines as well as STING→NF-κB pathway in the microglia and effector cytokines produced by the pathogenic Th17 cells. We also captured and identified the molecular properties of the feed-forward loop, which are two-cell entities of microglia-Th17, and proved them as the functional units of antigen presentation and bi-directional activation between the two cell types. Moreover, ACT001, an orphan drug to treat glioblastoma, disrupts this feed-forward activation loop by inhibiting the STING→NF-κB pathway in microglia, thereby alleviating EAE. These findings emphasize the importance of interactions and bi-directional activations between microglia and Th17 in the autoimmune neuroinflammation, and provide rationale for further investigation on ACT001 as therapeutic option for autoimmune inflammatory diseases driven by similar mechanisms.

APOE4 impairs macrophage lipophagy and promotes demyelination of spiral ganglion neurons in mouse cochleae

The ApoE-ε4 gene is a well-established genetic risk factor for neurodegenerative diseases, such as Alzheimer's disease and multiple sclerosis, which are characterized by axonal demyelination in the central nervous system. Recent studies have implicated ApoE-ε4 in age-related hearing loss (ARHL), suggesting a potential role of APOE4 isoform in peripheral nervous system degeneration. However, the role of APOE4 in ARHL are still unclear. In this study, we explored the potential role of APOE4 in axonal demyelination of spiral ganglion neurons (SGNs). ApoE-ε4/ε4 (APOE4) and ApoE-ε3/ε3 (APOE3) mice were used to characterize SGNs. The effect of APOE4 on phagocytosis and autophagy as well as intracellular cholesterol level was evaluated in resident cochlear macrophages (RCMs) and mouse bone marrow-derived macrophages (BMDMs). The results showed that significant axonal demyelination was observed in SGNs of 10-month-old APOE4 mice, accompanied by the presence of myelin debris engulfed by RCMs. Meanwhile, inhibited phagocytosis of myelin debris and impaired lipophagy were detected in APOE4 RCMs and APOE4 BMDMs with an aberrant accumulation of lipid droplets (LDs), which could be reversed by trehalose treatment. This study provided a deep insight into the pathogenesis of APOE4-induced axonal demyelination of SGNs associated with the impaired lipophagy in RCMs, which helped to elucidate the underlying mechanism of ApoE-ε4 in ARHL.

Nitrate ameliorates alcohol-induced cognitive impairment via oral microbiota

Alcohol use is associated with cognitive impairment and dysregulated inflammation. Oral nitrate may benefit cognitive impairment in aging through altering the oral microbiota. Similarly, the beneficial effects of nitrate on alcohol-induced cognitive decline and the roles of the oral microbiota merit investigation. Here we found that nitrate supplementation effectively mitigated cognitive impairment induced by chronic alcohol exposure in mice, reducing both systemic and neuroinflammation. Furthermore, nitrate restored the dysbiosis of the oral microbiota caused by alcohol consumption. Notably, removing the oral microbiota led to a subsequent loss of the beneficial effects of nitrate. Oral microbiota from donor alcohol use disordered humans who had been taking the nitrate intervention were transplanted into germ-free mice which then showed increased cognitive function and reduced neuroinflammation. Finally, we examined 63 alcohol drinkers with varying levels of cognitive impairment and found that lower concentrations of nitrate metabolism-related bacteria were associated with higher cognitive impairment and lower nitrate levels in plasma. These findings highlight the protective role of nitrate against alcohol-induced cognition impairment and neuroinflammation and suggest that the oral microbiota associated with nitrate metabolism and brain function may form part of a "microbiota-mouth-brain axis".

NLRP3 inflammasome in neuroinflammation and central nervous system diseases

Neuroinflammation plays an important role in the pathogenesis of various central nervous system (CNS) diseases. The NLRP3 inflammasome is an important intracellular multiprotein complex composed of the innate immune receptor NLRP3, the adaptor protein ASC, and the protease caspase-1. The activation of the NLRP3 inflammasome can induce pyroptosis and the release of the proinflammatory cytokines IL-1β and IL-18, thus playing a central role in immune and inflammatory responses. Recent studies have revealed that the NLRP3 inflammasome is activated in the brain to induce neuroinflammation, leading to further neuronal damage and functional impairment, and contributes to the pathological process of various neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, and stroke. In this review, we summarize the important role of the NLRP3 inflammasome in the pathogenesis of neuroinflammation and the pathological course of CNS diseases and discuss potential approaches to target the NLRP3 inflammasome for the treatment of CNS diseases.

The associations of cerebrospinal fluid ApoE and C1q with Alzheimer's disease biomarkers

BackgroundThe roles of complement 1q (C1q) and Apolipoprotein E (ApoE) in driving Alzheimer's disease (AD) progression might be explained by their associations with neuroinflammation and AD pathology which were previously reported.ObjectiveWe examined the associations of cerebrospinal fluid (CSF) C1q and ApoE with CSF neuroinflammatory biomarkers and AD core biomarkers, as well as explored whether C1q mediated the associations of CSF ApoE with these biomarkers.MethodsHere, we analyzed CSF proteomics data from Alzheimer's Disease Neuroimaging Initiative (ADNI) using two different ADNI proteomics datasets-SomaScan (n = 579)and multiple reaction monitoring (MRM[n = 207]). Linear regression analyses were conducted to explore the association of CSF ApoE and C1q. The mediation model and structural equation model (SEM) were conducted to explore the associations of ApoE and C1q with AD biomarkers.ResultsMultiple linear regression showed that CSF ApoE was positively associated with CSF C1q in total participants and Alzheimer's continuum participants. Mediation analyses indicated that C1q mediated the associations of CSF ApoE with CSF T-tau, P-tau, sTREM2 and GFAP (mediation proportions range from 15.06 to 44.64%; all the p values < 0.05) but not with CSF amyloid-β and progranulin (PGRN). The SEM yielded similar results.ConclusionsOur findings suggest that C1q is linked to ApoE, and it mediates the associations of ApoE with T-tau, P-tau, sTREM2, GFAP, indicating C1q association with ApoE might be involved in AD progression.

Allicin alleviates traumatic brain injury-induced neuroinflammation by enhancing PKC-δ-mediated mitophagy

BACKGROUND

Traumatic brain injury (TBI) leads to neuroinflammation, which is a key contributor to the negative prognosis in TBI patients. Recent evidence indicates that allicin can prevent neuronal injury after TBI. However, whether allicin alleviates neuroinflammation by promoting mitophagy is unclear.

PURPOSE

We investigated the suppressive effects of allicin on neuroinflammation and clarified the role of mitophagy in the underlying mechanism.

STUDY DESIGN/METHODS

The controlled cortical impact (CCI) was employed to effectively mimic TBI in a living system. Cellular mechanical damage was modeled in vitro using a Bv2 cell stretch model. Neuroinflammation was assessed by evaluating levels of TNF-α, IL-1β, IL-6, ROS, IL-4 and IL-10, along with the expression of NLRP3 and TLR4 proteins. RNA-sequence and KEGG analyses revealed allicin-regulated molecular processes in the Bv2 cell stretch model. Immunofluorescence staining was performed to label both the autophagy marker protein LC3 and the outer mitochondrial membrane (OMM) marker COX IV. Lipid MS and lipidomic analyses were used to determine the CL levels in the OMM and IMM. The characteristic bilayer structure of mitochondria was observed using transmission electron microscopy (TEM). PKC-δ expression and phosphorylated phospholipid scramblase-3 (PLS3) levels were detected via western blotting. Stretched Bv2 cells and primary neurons were cocultured to assess the anti-neuroinflammatory effects of allicin. Neuro-rehabilitation was assessed using behavioral experiments such as the rotarod and morris water maze (MWM) tests.

RESULTS

Allicin treatment reduced TNF-α, IL-1β, IL-6, ROS levels, and the expression of NLRP3 and TLR4 proteins in mice with CCI, while IL-4 and IL-10 levels remained unchanged. Additionally, allicin reduced tissue lesions and cell death after CCI. The transcriptomic analysis revealed that mitophagy was important in allicin-related molecular pathways. The translocation of CL from IMM to OMM was facilitated by allicin, as demonstrated by flow cytometry and lipidomic analyses. Importantly, allicin increased PKC-δ expression and PLS3 phosphorylation in the CL-related mitophagy process in both the CCI and Bv2 cell stretch models. These findings suggest that allicin reduces mitophagy-related neuroinflammation and further prevents neuronal injury in vitro. Rottlerin, a selective PKC-δ inhibitor, effectively diminished allicin's capacity to reduce neuroinflammation, correlating with worsened motor function and cognitive abilities. Thus, CCI-induced behavioral deficits were also ameliorated by the administration of allicin via a PKC-δ-related mitophagy.

CONCLUSIONS

This study uncovers a novel mechanism where allicin enhances PKC-δ expression and PLS3 phosphorylation, facilitating CL translocation to the OMM and activating mitophagy, thereby reducing TBI-induced neuroinflammation.

Multiple Sclerosis and Other Acquired Demyelinating Diseases of the Central Nervous System

Acquired demyelinating diseases of the central nervous system (CNS) comprise inflammatory conditions, including multiple sclerosis (MS) and related diseases, as well as noninflammatory conditions caused by toxic, metabolic, infectious, traumatic, and neurodegenerative insults. Here, we review the spectrum of diseases producing acquired CNS demyelination before focusing on the prototypical example of MS, exploring the pathologic mechanisms leading to myelin injury in relapsing and progressive MS and summarizing the mechanisms and modulators of remyelination. We highlight the complex interplay between the immune system, oligodendrocytes and oligodendrocyte progenitor cells (OPCs), and other CNS glia cells such as microglia and astrocytes in the pathogenesis and clinical course of MS. Finally, we review emerging therapeutic strategies that exploit our growing understanding of disease mechanisms to limit progression and promote remyelination.

The emerging role of the microglia triggering receptor expressed on myeloid cells (TREM) 2 in multiple sclerosis

BACKGROUND

The chronic inflammatory condition known as multiple sclerosis (MS) causes inflammation and demyelination in the central nervous system (CNS). The activation of multiple cell types, including the CNS's resident immune cells called microglia, is a component of the immunological response in MS. Recently, the triggering receptor expressed on myeloid cells (TREM) family has emerged as a crucial player in modulating microglial function and subsequent neuroinflammation. Understanding the role of TREM receptors in MS pathogenesis could provide insightful information on how to develop new therapeutic approaches.

MAIN BODY

The TREM family consists of several receptors, including TREM-1 and TREM-2, which can be expressed on both immune cells, such as myeloid cells and microglia, and non-immune cells. These receptors interact with their respective ligands and regulate signaling pathways, ultimately leading to the control of microglial activation and inflammatory reactions. TREM-2, in particular, has garnered significant interest because of its connection with MS and other neurodegenerative diseases. The activation of microglia through TREM receptors in MS is thought to influence the equilibrium between helpful and detrimental inflammatory responses. TREM receptors can promote the phagocytosis of myelin debris and remove apoptotic cells, thus contributing to tissue repair and regeneration. However, excessive or dysregulated activation of microglia mediated by TREM receptors can lead to the release of pro-inflammatory cytokines and neurotoxic factors, exacerbating neuroinflammation and neurodegeneration in MS.

CONCLUSION

The emerging role of the TREM family in demyelinating diseases highlights the importance of microglia in disease pathogenesis. Understanding the mechanisms by which TREM receptors modulate microglial function can provide valuable insights into the development of targeted therapies for these disorders. By selectively targeting TREM receptors, it may be possible to harness their beneficial effects on tissue repair while dampening their detrimental pro-inflammatory responses. Further research is warranted to elucidate the precise signaling pathways and ligand interactions involved in TREM-mediated microglial activation, which could uncover novel therapeutic avenues for treating MS and other neuroinflammatory disorders.

The protein kinase C modulator bryostatin-1 therapeutically targets microglia to attenuate neuroinflammation and promote remyelination

In multiple sclerosis (MS), microglia and macrophages within the central nervous system (CNS) play an important role in determining the balance among demyelination, neurodegeneration, and myelin repair. Phagocytic and regenerative functions of these CNS innate immune cells support remyelination, whereas chronic and maladaptive inflammatory activation promotes lesion expansion and disability, particularly in the progressive forms of MS. No currently approved drugs convincingly target microglia and macrophages within the CNS, contributing to the lack of therapies aimed at promoting remyelination and slowing disease progression for individuals with MS. Here, we found that the protein kinase C (PKC)-modulating drug bryostatin-1 (bryo-1), a CNS-penetrant compound with an established human safety profile, shifts the transcriptional programs of microglia and CNS-associated macrophages from a proinflammatory phenotype to a regenerative phenotype in vitro and in vivo. Treatment of microglia with bryo-1 stimulated scavenger pathways, phagocytosis, and secretion of factors that prevented the activation of neuroinflammatory reactive astrocytes while also promoting neuroaxonal health and oligodendrocyte differentiation. In line with these findings, systemic treatment of mice with bryo-1 augmented remyelination after a focal demyelinating injury. Our results demonstrate the potential of bryo-1 and possibly a wider class of PKC modulators as myelin-regenerative and supportive agents in MS and other neurologic diseases.

Deciphering the physiopathology of neurodevelopmental disorders using brain organoids

Neurodevelopmental disorders (NDD) encompass a range of conditions marked by abnormal brain development in conjunction with impaired cognitive, emotional and behavioural functions. Transgenic animal models, mainly rodents, traditionally served as key tools for deciphering the molecular mechanisms driving NDD physiopathology and significantly contributed to the development of pharmacological interventions aimed at treating these disorders. However, the efficacy of these treatments in humans has proven to be limited, due in part to the intrinsic constraint of animal models to recapitulate the complex development and structure of the human brain but also to the phenotypic heterogeneity found between affected individuals. Significant advancements in the field of induced pluripotent stem cells (iPSCs) offer a promising avenue for overcoming these challenges. Indeed, the development of advanced differentiation protocols for generating iPSC-derived brain organoids gives an unprecedented opportunity to explore human neurodevelopment. This review provides an overview of how 3D brain organoids have been used to investigate various NDD (i.e. Fragile X syndrome, Rett syndrome, Angelman syndrome, microlissencephaly, Prader-Willi syndrome, Timothy syndrome, tuberous sclerosis syndrome) and elucidate their pathophysiology. We also discuss the benefits and limitations of employing such innovative 3D models compared to animal models and 2D cell culture systems in the realm of personalized medicine.

Astrocytes and microglia in multiple sclerosis and neuromyelitis optica

Multiple sclerosis and neuromyelitis optica are autoimmune neurodegenerative diseases primarily targeting myelin sheath and neuroglia. In multiple sclerosis, autoantibodies destroy oligodendrocytes and myelin, which underlies primary neurologic symptoms. Focal damage to myelin triggers reactive astrogliosis and microgliosis, which contribute to and to a large extent define the disease progression. In neuromyelitis optica, autoantibodies against water channel aquaporin 4 (AQP4), which are localized at astrocytic endfeet mediate damage of the glia limitans thus facilitating infiltration of blood-borne molecules and cells that propagate the damage to nerves and neurons. This primary astrocytopathy recruits microglia, which contribute to the neuroinflammatory response. Neuroglial cells therefore are potential targets for cell-specific therapies.

HPGD: An Intermediate Player in Microglial Polarization and Multiple Sclerosis Regulated by Nr4a1

HPGD encodes 15-Hydroxyprostaglandin dehydrogenase catalyzing the decomposition of prostaglandin E2 and has not been reported in multiple sclerosis (MS). We previously found that Nr4a1 regulated microglia polarization and inhibited the progression of experimental autoimmune encephalomyelitis (EAE). Bioinformatics analysis suggested that HPGD might be regulated by Nr4a1. Therefore, this study aimed to explore the role of HPGD in microglia polarization and determine whether HPGD mediates the inhibition of EAE by Nr4a1. C57BL/6 mice were treated with MOG35-55 peptide to induce EAE. BV-2 cells were treated with LPS/IL-4 to induce M1/M2 polarization. We then analyzed the pathological changes of spinal cord tissue, detected the expression levels of M1/M2 genes in tissues and cells, and explored the effect of HPGD on PPARγ activation to clarify the role of HPGD in EAE. The interaction between HPGD and Nr4a1 was verified by ChIP and pull-down assay. HPGD was downregulated in the spinal cord of EAE mice and HPGD overexpression alleviated the progression of EAE. Experiments in vitro and in vivo revealed that HPGD inhibited M1 polarization, promoted M2 polarization and increased PPARγ-DNA complex level. Nr4a1 could bind to the promoter of HPGD and its overexpression increased HPGD level. HPGD overexpression (or knockdown) reversed the effect of Nr4a1 knockdown (or overexpression) on M1/2 polarization. HPGD is regulated by Nr4a1 and inhibits the progression of EAE through shifting the M1/M2 polarization and promoting the activation of PPARγ signaling pathway. This study provides potential targets and basis for the development of MS therapeutic drugs.

Neurological, psychological, psychosocial complications of long-COVID and their management

Since it first appeared, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has had a significant and lasting negative impact on the health and economies of millions of individuals all over the globe. At the level of individual health too, many patients are not recovering fully and experiencing a long-term condition now commonly termed 'long-COVID'. Long-COVID is a collection of symptoms which must last more than 12 weeks following initial COVID infection, and which cannot be adequately explained by alternate diagnoses. The neurological and psychosocial impact of long-COVID is itself now a global health crisis and therefore preventing, diagnosing, and managing these patients is of paramount importance. This review focuses primarily on: neurological functioning deficits; mental health impacts; long-term mood problems; and associated psychosocial issues, among patients suffering from long-COVID with an eye towards the neurological basis of these symptoms. A concise account of the clinical relevance of the neurological and psychosocial impacts of long-COVID, the effects on long-term morbidity, and varied approaches in managing patients with significant chronic neurological symptoms and conditions was extracted from the literature, analysed and reported. A comprehensive account of plausible pathophysiological mechanisms involved in the development of long-COVID, its management, and future research needs have been discussed.

The emerging role of microglia in the development and therapy of multiple sclerosis

Microglia are innate immune cells that maintain homeostasis of the central nervous system (CNS) and affect various neurodegenerative diseases, especially multiple sclerosis (MS). MS is an autoimmune disease of the CNS characterized by persistent inflammation, diffuse axonal damage, and microglia activation. Recent studies have shown that microglia are extremely related to the pathological state of MS and play an important role in the development of MS. This article reviews the multiple roles of microglia in the progression of MS, including the regulatory role of microglia in inflammation, remyelination, oxidative stress, the influence of phagocytosis and antigen-presenting capacity of microglia, and the recent progress by using microglia as a target for MS therapy. Microglia modulation may be a potential way for better MS therapy.

Inflammasomes in neurodegenerative diseases

Inflammasomes represent a crucial component of the innate immune system, which respond to threats by recognizing different molecules. These are known as pathogen-associated molecular patterns (PAMPs) or host-derived damage-associated molecular patterns (DAMPs). In neurodegenerative diseases and neuroinflammation, the accumulation of misfolded proteins, such as beta-amyloid and alpha-synuclein, can lead to inflammasome activation, resulting in the release of interleukin (IL)-1β and IL-18. This activation also induces pyroptosis, the release of inflammatory mediators, and exacerbates neuroinflammation. Increasing evidence suggests that inflammasomes play a pivotal role in neurodegenerative diseases. Therefore, elucidating and investigating the activation and regulation of inflammasomes in these diseases is of paramount importance. This review is primarily focused on evidence indicating that inflammasomes are activated through the canonical pathway in these diseases. Inflammasomes as potential targets for treating neurodegenerative diseases are also discussed.

Mitigating neurodegenerative diseases: the protective influence of baicalin and baicalein through neuroinflammation regulation

Neurodegenerative diseases (NDDs) represent a category of serious illnesses characterized by the progressive deterioration of neuronal structure and function. The exploration of natural compounds as potential therapeutic agents has gained increasing attention in recent years owing to their wide range of pharmacological activities and minimal side effects. Baicalin (BAI) and baicalein (BE), polyphenolic flavonoids, derived from the root of Scutellaria baicalensis, evidently show potential in treating NDDs. This review provides an overview of the current understanding of the roles of BAI and BE in alleviating neuroinflammation, a pivotal pathological process implicated in various NDDs. Studies conducted prior to clinical trials have shown that BAI and BE exert protective effects on the nervous system in different animal models of NDDs. Furthermore, mechanistic studies indicate that BAI and BE exert anti-inflammatory effects by inhibiting pro-inflammatory cytokines, suppressing microglial activation, and regulating microglial phenotypes. These effects are mediated through the modulation of inflammatory signaling cascades, including Toll-like receptor 4 (TLR4), mitogen-activated protein kinase (MAPK), amp-activated protein kinase (AMPK), NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome, and nuclear factor erythroid 2-related factor 2 (Nrf2)/hemoglobin oxygenase-1 (HO-1). Overall, BAI and BE exhibit promising potential as natural compounds with anti-inflammatory properties and offer innovative therapeutic approaches for managing NDDs.

Temporal dynamics of neutrophil functions in multiple sclerosis

Early neuroinflammatory injury plays a crucial role in initiating and progressing multiple sclerosis (MS). Neutrophils are forerunners to neural lesions in MS, yet the temporal alterations of their functions in MS remains unclear. This study demonstrated a positive correlation between circulatory neutrophil counts and disease activity and severity in treatment-naïve MS patients. In experimental autoimmune encephalomyelitis (EAE), we documented the recruitment of neutrophils to spinal cord during the preclinical phase, with these cells contributing to the disruption of the blood-spinal cord barrier (BSCB) during the onset of the disease. Furthermore, during the peak phase, infiltrated neutrophils promoted demyelination through formation of neutrophil extracellular traps (NETs), cytokine secretion and antigen presentation. Notably, the inhibition of neutrophil infiltration using a CXCR2 inhibitor effectively mitigated white matter damage and physical disability, underscoring their potential as therapeutic targets. In conclusion, neutrophils represent promising candidates for both disease treatment and prognosis evaluation in MS. By elucidating their temporal roles and mechanisms of action, we can potentially harness their modulation to improve patient outcomes and disease management.

Role of microglia polarization induced by glucose metabolism disorder in the cognitive impairment of mice from PM2.5 exposure

Studies have found that PM2.5 can damage the brain, accelerate cognitive impairment, and increase the risk of developing a variety of neurodegenerative diseases. However, the potential molecular mechanisms by which PM2.5 causes learning and memory problems are yet to be explored. In this study, we evaluated the neurotoxic effects in mice after 12 weeks of PM2.5 exposure, and found that this exposure resulted in learning and memory disorders, pathological brain damage, and M1 phenotype polarization on microglia, especially in the hippocampus. The severity of this damage increased with increasing PM2.5 concentration. Proteomic analysis, as well as validation results, suggested that PM2.5 exposure led to abnormal glucose metabolism in the mouse brain, which is mainly characterized by significant expression of hexokinase, phosphofructokinase, and lactate dehydrogenase. We therefore administered the glycolysis inhibitor 2-deoxy-d-glucose (2-DG) to the mice exposed to PM2.5, and showed that inhibition of glycolysis by 2-DG significantly alleviated PM2.5-induced hippocampal microglia M1 phenotype polarization, and reduced the release of inflammatory factors, improved synaptic structure and related protein expression, which alleviated the cognitive impairment induced by PM2.5 exposure. In summary, our study found that abnormal glucose metabolism-mediated inflammatory polarization of microglia played a role in learning and memory disorders in mice exposed to PM2.5. This study provides new insights into the neurotoxicity caused by PM2.5 exposure, and provides some theoretical references for the prevention and control of cognitive impairment induced by PM2.5 exposure.

The cGAS-STING pathway drives neuroinflammation and neurodegeneration via cellular and molecular mechanisms in neurodegenerative diseases

Neurodegenerative diseases (NDs) are a type of common chronic progressive disorders characterized by progressive damage to specific cell populations in the nervous system, ultimately leading to disability or death. Effective treatments for these diseases are still lacking, due to a limited understanding of their pathogeneses, which involve multiple cellular and molecular pathways. The triggering of an immune response is a common feature in neurodegenerative disorders. A critical challenge is the intricate interplay between neuroinflammation, neurodegeneration, and immune responses, which are not yet fully characterized. In recent years, the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING) pathway, a crucial immune response for intracellular DNA sensing, has gradually gained attention. However, the specific roles of this pathway within cellular types such as immune cells, glial and neuronal cells, and its contribution to ND pathogenesis, remain not fully elucidated. In this review, we systematically explore how the cGAS-STING signaling links various cell types with related cellular effector pathways under the context of NDs for multifaceted therapeutic directions. We emphasize the discovery of condition-dependent cellular heterogeneity in the cGAS-STING pathway, which is integral for understanding the diverse cellular responses and potential therapeutic targets. Additionally, we review the pathogenic role of cGAS-STING activation in Parkinson's disease, ataxia-telangiectasia, and amyotrophic lateral sclerosis. We focus on the complex bidirectional roles of the cGAS-STING pathway in Alzheimer's disease, Huntington's disease, and multiple sclerosis, revealing their double-edged nature in disease progression. The objective of this review is to elucidate the pivotal role of the cGAS-STING pathway in ND pathogenesis and catalyze new insights for facilitating the development of novel therapeutic strategies.

Therapeutic approaches to microglial dysfunction in Alzheimer's disease: Enhancing phagocytosis and metabolic regulation

Microglia are essential in neurogenesis, synaptic pruning, and homeostasis. Nevertheless, aging, and cellular senescence may modify their role, causing them to shift from being shields to being players of neurodegeneration. In the aging brain, the population of microglia increases, followed by enhanced activity of genes related to neuroinflammation. This change increases their ability to cause inflammation, resulting in a long-lasting state of inflammation in the brain that harms the condition of neurons. In Alzheimer's Disease (AD), microglia are located inside amyloid plaques and exhibit an inflammatory phenotype characterized by a diminished ability to engulf and remove waste material, worsening the illness's advancement. Genetic polymorphisms in TREM2, APOE, and CD33 highlight the significant impact of microglial dysfunction in AD. This review examines therapeutic approaches that aim to address microglial dysfunction, such as enhancing the microglial capability to engulf and remove amyloid-β clumps and regulating microglial metabolism and mitochondrial activity. Microglial transplanting and reprogramming advancements show the potential to restore their ability to reduce inflammation. Although there has been notable advancement, there are still voids in our knowledge of microglial biology, including their relationships with other brain cells. Further studies should prioritize the improvement of human AD models, establish standardized methods for characterizing microglia, and explore how various factors influence microglial responses. It is essential to tackle these problems to create effective treatment plans that focus on reducing inflammation in the brain and protecting against damage in age-related neurodegenerative illnesses.

Dysbiosis and fecal microbiota transplant: Contemplating progress in health, neurodegeneration and longevity

The gut-brain axis plays an important role in mental health. The intestinal epithelial surface is colonized by billions of commensal and transitory bacteria, known as the Gut Microbiota (GM). However, potential pathogens continuously stimulate intestinal immunity when they find the place. The last two decades have witnessed several studies revealing intestinal bacteria as a key factor in the health-disease balance of the gut, as well as disease-emergent in other parts of the body. Various neurological processes, such as cognition, learning, and memory, could be affected by dysbiosis in GM. Additionally, the aging process and longevity are related to systemic inflammation caused by dysbiosis. Commensal GM affects brain development, behavior, and healthy aging suggesting that building changes in GM might be a potential therapeutic method. The innovation in GM dysbiosis is intervention by Fecal Microbiota Transplantation (FMT), which has been confirmed as a therapy for recurrent Clostridium difficile infections and is promising for other clinical disorders, such as Parkinson's disease, Multiple Sclerosis (MS), Alzheimer's disease, and depression. Additionally, FMT may be possible to promote healthy aging, and extend longevity. This review aims to connect dysbiosis, neurological disorders, and aging and the potential of FMT as a therapeutic strategy to treat these disorders, and to enhance the quality of life in the elderly.

Human Umbilical Cord-Mesenchymal Stem Cells Promote Extracellular Matrix Remodeling in Microglia

Human mesenchymal stem cells modulate the immune response and are good candidates for cell therapy in neuroinflammatory brain disorders affecting both adult and premature infants. Recent evidence indicates that through their secretome, mesenchymal stem cells direct microglia, brain-resident immune cells, toward pro-regenerative functions, but the mechanisms underlying microglial phenotypic transition are still under investigation. Using an in vitro coculture approach combined with transcriptomic analysis, we identified the extracellular matrix as the most relevant pathway altered by the human mesenchymal stem cell secretome in the response of microglia to inflammatory cytokines. We confirmed extracellular matrix remodeling in microglia exposed to the mesenchymal stem cell secretome via immunofluorescence analysis of the matrix component fibronectin and the extracellular crosslinking enzyme transglutaminase-2. Furthermore, an analysis of hallmark microglial functions revealed that changes in the extracellular matrix enhance ruffle formation by microglia and cell motility. These findings point to extracellular matrix changes, associated plasma membrane remodeling, and enhanced microglial migration as novel mechanisms by which mesenchymal stem cells contribute to the pro-regenerative microglial transition.

Microglia signaling in health and disease - Implications in sex-specific brain development and plasticity

Microglia, the intrinsic neuroimmune cells residing in the central nervous system (CNS), exert a pivotal influence on brain development, homeostasis, and functionality, encompassing critical roles during both aging and pathological states. Recent advancements in comprehending brain plasticity and functions have spotlighted conspicuous variances between male and female brains, notably in neurogenesis, neuronal myelination, axon fasciculation, and synaptogenesis. Nevertheless, the precise impact of microglia on sex-specific brain cell plasticity, sculpting diverse neural network architectures and circuits, remains largely unexplored. This article seeks to unravel the present understanding of microglial involvement in brain development, plasticity, and function, with a specific emphasis on microglial signaling in brain sex polymorphism. Commencing with an overview of microglia in the CNS and their associated signaling cascades, we subsequently probe recent revelations regarding molecular signaling by microglia in sex-dependent brain developmental plasticity, functions, and diseases. Notably, C-X3-C motif chemokine receptor 1 (CX3CR1), triggering receptors expressed on myeloid cells 2 (TREM2), calcium (Ca2+), and apolipoprotein E (APOE) emerge as molecular candidates significantly contributing to sex-dependent brain development and plasticity. In conclusion, we address burgeoning inquiries surrounding microglia's pivotal role in the functional diversity of developing and aging brains, contemplating their potential implications for gender-tailored therapeutic strategies in neurodegenerative diseases.

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

Astrocyte-Mediated Neuroinflammation in Neurological Conditions

Astrocytes are one of the key glial types of the central nervous system (CNS), accounting for over 20% of total glial cells in the brain. Extensive evidence has established their indispensable functions in the maintenance of CNS homeostasis, as well as their broad involvement in neurological conditions. In particular, astrocytes can participate in various neuroinflammatory processes, e.g., releasing a repertoire of cytokines and chemokines or specific neurotrophic factors, which result in both beneficial and detrimental effects. It has become increasingly clear that such astrocyte-mediated neuroinflammation, together with its complex crosstalk with other glial cells or immune cells, designates neuronal survival and the functional integrity of neurocircuits, thus critically contributing to disease onset and progression. In this review, we focus on the current knowledge of the neuroinflammatory responses of astrocytes, summarizing their common features in neurological conditions. Moreover, we highlight several vital questions for future research that promise novel insights into diagnostic or therapeutic strategies against those debilitating CNS diseases.

Bone marrow-derived mesenchymal stem cell-derived exosome-loaded miR-129-5p targets high-mobility group box 1 attenuates neurological-impairment after diabetic cerebral hemorrhage

BACKGROUND

Diabetic intracerebral hemorrhage (ICH) is a serious complication of diabetes. The role and mechanism of bone marrow mesenchymal stem cell (BMSC)-derived exosomes (BMSC-exo) in neuroinflammation post-ICH in patients with diabetes are unknown. In this study, we investigated the regulation of BMSC-exo on hyperglycemia-induced neuroinflammation.

AIM

To study the mechanism of BMSC-exo on nerve function damage after diabetes complicated with cerebral hemorrhage.

METHODS

BMSC-exo were isolated from mouse BMSC media. This was followed by transfection with microRNA-129-5p (miR-129-5p). BMSC-exo or miR-129-5p-overexpressing BMSC-exo were intravitreally injected into a diabetes mouse model with ICH for in vivo analyses and were cocultured with high glucose-affected BV2 cells for in vitro analyses. The dual luciferase test and RNA immunoprecipitation test verified the targeted binding relationship between miR-129-5p and high-mobility group box 1 (HMGB1). Quantitative polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay were conducted to assess the levels of some inflammation factors, such as HMGB1, interleukin 6, interleukin 1β, toll-like receptor 4, and tumor necrosis factor α. Brain water content, neural function deficit score, and Evans blue were used to measure the neural function of mice.

RESULTS

Our findings indicated that BMSC-exo can promote neuroinflammation and functional recovery. MicroRNA chip analysis of BMSC-exo identified miR-129-5p as the specific microRNA with a protective role in neuroinflammation. Overexpression of miR-129-5p in BMSC-exo reduced the inflammatory response and neurological impairment in comorbid diabetes and ICH cases. Furthermore, we found that miR-129-5p had a targeted binding relationship with HMGB1 mRNA.

CONCLUSION

We demonstrated that BMSC-exo can reduce the inflammatory response after ICH with diabetes, thereby improving the neurological function of the brain.

Bone marrow-derived mesenchymal stem cell-derived exosome-loaded miR-129-5p targets high-mobility group box 1 attenuates neurological-impairment after diabetic cerebral hemorrhage

BACKGROUND

Diabetic intracerebral hemorrhage (ICH) is a serious complication of diabetes. The role and mechanism of bone marrow mesenchymal stem cell (BMSC)-derived exosomes (BMSC-exo) in neuroinflammation post-ICH in patients with diabetes are unknown. In this study, we investigated the regulation of BMSC-exo on hyperglycemia-induced neuroinflammation.

AIM

To study the mechanism of BMSC-exo on nerve function damage after diabetes complicated with cerebral hemorrhage.

METHODS

BMSC-exo were isolated from mouse BMSC media. This was followed by transfection with microRNA-129-5p (miR-129-5p). BMSC-exo or miR-129-5p-overexpressing BMSC-exo were intravitreally injected into a diabetes mouse model with ICH for in vivo analyses and were cocultured with high glucose-affected BV2 cells for in vitro analyses. The dual luciferase test and RNA immunoprecipitation test verified the targeted binding relationship between miR-129-5p and high-mobility group box 1 (HMGB1). Quantitative polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay were conducted to assess the levels of some inflammation factors, such as HMGB1, interleukin 6, interleukin 1β, toll-like receptor 4, and tumor necrosis factor α. Brain water content, neural function deficit score, and Evans blue were used to measure the neural function of mice.

RESULTS

Our findings indicated that BMSC-exo can promote neuroinflammation and functional recovery. MicroRNA chip analysis of BMSC-exo identified miR-129-5p as the specific microRNA with a protective role in neuroinflammation. Overexpression of miR-129-5p in BMSC-exo reduced the inflammatory response and neurological impairment in comorbid diabetes and ICH cases. Furthermore, we found that miR-129-5p had a targeted binding relationship with HMGB1 mRNA.

CONCLUSION

We demonstrated that BMSC-exo can reduce the inflammatory response after ICH with diabetes, thereby improving the neurological function of the brain.

Tirofiban mediates neuroprotective effects in acute ischemic stroke by reducing inflammatory response

Growing evidence suggests that neuroinflammation is a critical driver of the development, worsening, and cell death observed in acute ischemic stroke (AIS). While prior research has demonstrated that tirofiban enhances functional recovery in AIS patients by suppressing platelet aggregation, its impact and underlying mechanisms in AIS-related neuroinflammation remain elusive. The current study established an AIS mouse model employing photochemical techniques and assessed neurological function and brain infarct size using the modified neurological severity scale (mNSS) and 2,3,5-Triphenyltetrazolium chloride (TTC) staining, respectively. Tirofiban significantly reduced the volume of cerebral infarction in AIS mice, accompanied by an enhancement in their neurological functions. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays along with experiments assessing oxidative stress showed that tirofiban mitigated oxidative damage and apoptosis in the ischemic penumbra post-AIS. Additionally, DNA microarray analysis revealed alterations in gene expression patterns in the ischemic penumbra after tirofiban treatment. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that most gene-level downregulated signaling pathways were closely related to the inflammatory response. Moreover, the protein microarray analysis revealed that tirofiban diminished the expression levels of inflammatory cytokines, such as interleukin-1 (IL-1), IL-6, and tumor necrosis factor-alpha, in the ischemic penumbra. Additionally, immunofluorescence staining showed that tirofiban regulated inflammatory responses by altering the state and phenotype of microglia. In conclusion, this study suggests that tirofiban reduces inflammatory response by regulating microglial state and phenotype and lowering the levels of inflammatory factors, providing neuroprotection in acute ischemic stroke.

Neurotoxic effects of triclosan in adolescent mice: Pyruvate kinase M2 dimer regulated Signal transducer and activator of transcription 3 phosphorylation mediated microglia activation and neuroinflammation

Triclosan (TCS), a commonly used antibacterial agent, is associated with various harmful effects on mammalian neurodevelopment, particularly when exposed prenatally. This study investigated the impact of long-term exposure to TCS on the prefrontal cortex development in adolescent mice. We evaluated the motor ability, motor coordination, and anxiety behavior of mice using open field tests (OFT) and elevated cross maze tests (EPM). An increase in movement distance, number of passes through the central area, and open arm retention time was observed in mice treated with TCS. Hematoxylin eosin staining and Nissl staining also showed significant adverse reactions in the brain tissue of TCS-exposed group. TCS induced microglia activation and increased inflammatory factors expression in the prefrontal cortex. TCS also increased the expression of pyruvate kinase M2 (PKM2), thereby elevating the levels of PKM2 dimer, which entered the nucleus. Treatment with TEPP46 (PKM2 dimer nuclear translocation inhibitor) blocked the expression of inflammatory factors induced by TCS. TCS induced the phosphorylation of nuclear signal transducer and activator of transcription 3 (STAT3) in vivo and in vitro, upregulating the levels of inflammatory cytokines. The results also demonstrated the binding of PKM2 to STAT3, which promoted STAT3 phosphorylation at the Tyr705 site, thereby regulating the expression of inflammatory factors. These findings highlight the role of PKM2-regulated STAT3 phosphorylation in TCS-induced behavioral disorders in adolescents and propose a reliable treatment target for TCS.

Does hazelnut consumption affect brain health and function against neurodegenerative diseases?

INTRODUCTION

A healthy daily diet and consuming certain nutrients, such as polyphenols, vitamins, and unsaturated fatty acids, may help neuronal health maintenance. Polyphenolic chemicals, which have antioxidant and anti-inflammatory properties, are involved in the neuroprotective pathway. Because of their nutritional value, nuts have been shown in recent research to be helpful in neuroprotection.

OBJECTIVE

Hazelnut is often consumed worldwide in various items, including processed foods, particularly in bakery, chocolate, and confectionery products. This nut is an excellent source of vitamins, amino acids, tocopherols, phytosterols, polyphenols, minerals, and unsaturated fatty acids. Consuming hazelnut may attenuate the risk of neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and Huntington's disease due to its anti-inflammatory and anti-oxidant qualities.

RESULTS

Many documents introduce hazelnut as an excellent choice to provide neuroprotection against neurodegenerative disorders and there is some direct proof of its neuroprotective effects.

DISCUSSION

So hazelnut consumption in daily diet may reduce neurodegenerative disease risk and be advantageous in reducing the imposed costs of dealing with neurodegenerative diseases.

Longitudinal Optical Coherence Tomography Imaging Reveals Hyperreflective Foci Characteristics in Relapsing-Remitting Multiple Sclerosis Patients

Background/Objectives: Retinal hyperreflective foci, 25-50 µm in diameter, that can be imaged by noninvasive optical coherence tomography (OCT) may represent microglial activity related to inflammation. This study aimed to detect hyperreflective foci in the OCT-hyporeflective avascular outer nuclear layer of the retina in relapsing-remitting MS (RRMS) patients without ongoing eye or optic nerve disease. Methods: A cohort of 13 RRMS patients (8 eyes with and 18 eyes without prior optic neuritis) underwent retinal OCT at baseline, after 1 month, after 6 months, and then every 6 months for 3 years. The data were compared with single-examination data from 106 eyes in 53 age-matched healthy subjects. Results: The prevalence of hyperreflective foci at baseline was higher in RRMS patients than in healthy subjects (46.2% vs. 1.8%, p < 0.005). Patients with optic neuritis had much more foci than those without (p < 0.001). Hyperreflective foci recurred in 23.1% of RRMS patients, bilaterally in one with prior optic neuritis and unilaterally in two without. Conclusions: Patients with RRMS, notably those with prior optic neuritis, had elevated rates of retinal infiltration in the absence of retinal disease, suggesting that the phenomenon may represent elevated activity of an immune surveillance or housekeeping mechanism rather than retinal disease.

Inflammatory Role of CCR1 in the Central Nervous System

BACKGROUND

Chemokine ligands and their corresponding receptors are essential for regulating inflammatory responses. Chemokine receptors can stimulate immune activation or inhibit/promote signaling pathways by binding to specific chemokine ligands. Among these receptors, CC chemokine receptor 1 (CCR1) is extensively studied as a G protein-linked receptor target, predominantly expressed in various leukocytes, and is considered a promising target for anti-inflammatory therapy. Furthermore, CCR1 is essential for monocyte extravasation and transportation in inflammatory conditions. Its involvement in inflammatory diseases of the central nervous system (CNS), including multiple sclerosis, Alzheimer's disease, and stroke, has been extensively studied along with its ligands. Animal models have demonstrated the beneficial effects resulting from inhibiting CCR1 or its ligands.

SUMMARY

This review demonstrates the significance of CCR1 in CNS inflammatory diseases, the molecules implicated in the inflammatory pathway, and potential drugs or molecules for treating CNS diseases. This evidence may offer new targets or strategies for treating inflammatory CNS diseases.

Multisensory gamma stimulation mitigates the effects of demyelination induced by cuprizone in male mice

Demyelination is a common pathological feature in a wide range of diseases, characterized by the loss of myelin sheath and myelin-supporting oligodendrocytes. These losses lead to impaired axonal function, increased vulnerability of axons to damage, and result in significant brain atrophy and neuro-axonal degeneration. Multiple pathomolecular processes contribute to neuroinflammation, oligodendrocyte cell death, and progressive neuronal dysfunction. In this study, we use the cuprizone mouse model of demyelination to investigate long-term non-invasive gamma entrainment using sensory stimulation as a potential therapeutic intervention for promoting myelination and reducing neuroinflammation in male mice. Here, we show that multisensory gamma stimulation mitigates demyelination, promotes oligodendrogenesis, preserves functional integrity and synaptic plasticity, attenuates oligodendrocyte ferroptosis-induced cell death, and reduces brain inflammation. Thus, the protective effects of multisensory gamma stimulation on myelin and anti-neuroinflammatory properties support its potential as a therapeutic approach for demyelinating disorders.

Regulatory T cells as a possible new target in epilepsy?

Epilepsy is a complex chronic brain disorder with diverse clinical features that can be caused by various triggering events, such as infections, head trauma, or stroke. During epileptogenesis, various abnormalities are observed, such as altered cellular homeostasis, imbalance of neurotransmitters, tissue changes, and the release of inflammatory mediators, which in combination lead to spontaneous recurrent seizures. Regulatory T cells (Tregs), a subtype of CD4+Foxp3+ T cells, best known for their key function in immune suppression, also seem to play a role in attenuating neurodegeneration and suppressing pathological inflammation in several brain disease states. Considering that epilepsy is also highly associated with neuronal damage and neuroinflammation, modulation of Tregs may be an interesting way to modify the disease course of epilepsy and needs further investigation. In this review, we will describe the currently available information on Tregs in epilepsy.

STIM2 Suppression Blocks Glial Activation to Alleviate Brain Ischemia Reperfusion Injury via Inhibition of Inflammation and Pyroptosis

Cerebral ischemia/reperfusion injury (CIRI) involves various pathogenic mechanisms, including cytotoxicity, apoptosis, inflammation, and pyroptosis. Stromal interactive molecule 2 (STIM2) is implicated in cerebral ischemia. Consequently, this study investigates the biological functions of STIM2 and its related mechanisms in CIRI progression. Middle cerebral artery occlusion/reperfusion (MCAO/R) mouse models and oxygen-glucose deprivation/reoxygenation (OGD/R) cellular models were established. STIM2 level was upregulated in experimental CIRI models, as shown by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting and immunofluorescence staining. Brain infarction and edema were attenuated by STIM2 knockdown, as 2,3,5-triphenyltetrazolium chloride (TTC) staining and brain water content evaluation revealed. STIM2 knockdown relieved neuronal apoptosis, microglia activation, inflammation and pyroptosis in MCAO/R mice, as detected by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining, enzyme-linked immunosorbent assay (ELISA) and western blotting. Results of flow cytometry, ELISA, western blotting and cell counting kit-8 (CCK-8) assays also showed that STIM2 knockdown inhibited inflammation, apoptosis and pyroptosis in OGD/R-treated BV2 cells. Moreover, STIM2 knockdown inhibited apoptosis and pyroptosis in PC12 cells incubated with conditioned medium collected from OGD/R-exposed BV2 cells. Mechanistically, lncRNA Malat1 (metastasis associated lung adenocarcinoma transcript 1) positively regulated STIM2 expression by sponging miR-30d-5p. Their binding relationship was confirmed by luciferase reporter assays. Finally, lncRNA Malat1 elevation or miR-30d-5p knockdown abolished the sh-STIM2-induced inhibition in cell damage. In conclusion, STIM2 knockdown in microglia alleviates CIRI by inhibiting microglial activation, inflammation, apoptosis, and pyroptosis.

TET1 mediated m5C modification of RelB aggravates cerebral ischemia/reperfusion-induced neuroinflammation through regulating microglia polarization

Microglia mediated neuroinflammation is one of the major contributors to brain damage in cerebral ischemia reperfusion injury (CI/RI). Recently, RNA modification was found to contribute to the regulation of microglia polarization and the subsequent development of cerebral I/R neuroinflammation. Herein, we investigated the effect and mechanism of m5C RNA modification in the microglia induced CI/RI neuroinflammation. We found that the m5C RNA modification levels decreased in the primary microglia isolated from a mouse model of intraluminal middle cerebral artery occlusion/reperfusion (MCAO/R) and the BV2 microglial cells subjected to oxygen-glucose deprivation and reoxygenation (OGD/R), and this change was accompanied by an increase in the M1/M2 polarization ratio. Furthermore, the expression of m5C demethylase TET1 in microglia increased, which promoted M1 polarization but impeded M2 polarization. Mechanistically, the higher TET1 expression decreased the m5C modification level of RelB and enhanced its mRNA stability, which subsequently increased the M1/M2 polarization ratio. In conclusion, this study provides insight into the role of m5C RNA modification in the pathogenesis of cerebral I/R neuroinflammation and may deepen our understanding on clinical therapy targeting the TET1-RelB axis.

Exploring the Significance of Microglial Phenotypes and Morphological Diversity in Neuroinflammation and Neurodegenerative Diseases: From Mechanisms to Potential Therapeutic Targets

Studying various microglial phenotypes and their functions in neurodegenerative diseases is crucial due to the intricate nature of their phenomics and their vital immunological role. Microglia undergo substantial phenomic changes, encompassing morphological, transcriptional, and functional aspects, resulting in distinct cell types with diverse structures, functions, properties, and implications. The traditional classification of microglia as ramified, M1 (proinflammatory), or M2 (anti-inflammatory) phenotypes is overly simplistic, failing to capture the wide range of recently identified microglial phenotypes in various brain regions affected by neurodegenerative diseases. Altered and activated microglial phenotypes deviating from the typical ramified structure are significant features of many neurodegenerative conditions. Understanding the precise role of each microglial phenotype is intricate and sometimes contradictory. This review specifically focuses on elucidating recent modifications in microglial phenotypes within neurodegenerative diseases. Recognizing the heterogeneity of microglial phenotypes in diseased states can unveil novel therapeutic strategies for targeting microglia in neurodegenerative diseases. Moreover, the exploration of the use of healthy isolated microglia to mitigate disease progression has provided an innovative perspective. In conclusion, this review discusses the dynamic landscape of mysterious microglial phenotypes, emphasizing the need for a nuanced understanding to pave the way for innovative therapeutic strategies for neurodegenerative diseases.

Glycoprotein Non-metastatic Melanoma Protein B (GPNMB) Protects Against Neuroinflammation and Neuronal Loss in Pilocarpine-induced Epilepsy via the Regulation of Microglial Polarization

Epilepsy is a progressive neurodegenerative disease highlighted by recurrent seizures, neuroinflammation, and the loss of neurons. Microglial dysfunction is commonly found in epileptic foci and contributes to neuroinflammation in the initiation and progression of epilepsy. Glycoprotein non-metastatic melanoma protein B (GPNMB), a transmembrane glycoprotein, has been involved in the microglial activation and neuroinflammation response. The present study investigated the functional significance of GPNMB in epilepsy. A proven model of epilepsy was established by intraperitoneal injection of pilocarpine to male Sprague Dawley rats. Lentivirus vectors carrying GPNMB or GPNMB short hairpin RNA (shGPNMB) were injected into the hippocampus to induce overexpression or knockdown of GPNMB. GPNMB expression was significantly upregulated and overexpression of GPNMB in the hippocampus reduced seizure activity and neuronal loss after status epilepticus (SE). We here focused on the effects of GPNMB deficiency on neuronal injury and microglia polarization 28 days after SE. GPNMB knockdown accelerated neuronal damage in the hippocampus, evidenced by increased neuron loss and neuronal cell apoptosis. Following GPNMB knockdown, M1 polarization (iNOS) and secretion of pro-inflammatory cytokines IL-6, IL-1β, and TNF-α were increased, and M2 polarization (Arg1) and secretion of anti-inflammatory cytokines IL-4, IL-10, and TGF-β were decreased. BV2 cells were used to further confirm the regulatory role of GPNMB in modulating phenotypic transformations and inflammatory cytokine expressions in microglia. In conclusion, these results indicated that GPNMB suppressed epilepsy through repression of hippocampal neuroinflammation, suggesting that GPNMB might be considered the potential neurotherapeutic target for epilepsy management and play a protective role against epilepsy by modulating the polarization of microglia.

Coffee and multiple sclerosis (MS)

Multiple Sclerosis (MS) is a long-term autoimmune disorder affecting the central nervous system, marked by inflammation, demyelination, and neurodegeneration. While the exact cause of MS remains unknown, recent research indicates that environmental factors, particularly diet, may influence the disease's risk and progression. As a result, the potential neuroprotective effects of coffee, one of the most popular beverages worldwide, have garnered significant attention due to its rich content of bioactive compounds. This chapter explores the impact of coffee consumption on patients with Multiple Sclerosis, highlighting how coffee compounds like caffeine, polyphenols, and diterpenes can reduce inflammation and oxidative stress while enhancing neural function. It highlights caffeine's effect in regulating adenosine receptors, specifically A1R and A2AR, which play important roles in neuroinflammation and neuroprotection in MS. The dual role of microglial cells, which promote inflammation while also aiding neuroprotection, is also highlighted concerning caffeine's effects. Furthermore, the potential of A2AR as a therapeutic target in MS and the non-A2AR-dependent neuroprotective benefits of coffee. In this chapter we suggest that the consumption of coffee has no harmful effect on an MS patient and to a larger extent on public health, and informs future research directions and clinical practice, ultimately improving outcomes for individuals living with MS.

Causal effects of autoimmune diseases on temporomandibular disorders and the mediating pathways: a Mendelian randomization study

Background

The role of autoimmune diseases (ADs) in temporomandibular disorders (TMDs) has been emphasized in observational studies. However, whether the causation exists is unclear, and controversy remains about which specific disorder is destructive in TMDs. This Mendelian randomization (MR) study aims to estimate the causal effect of common ADs on TMDs.

Methods

Genetic data from published genome-wide association studies for fourteen common ADs, specifically multiple sclerosis (MS, N = 15,283), ankylosing spondylitis (AS, N = 22,647), asthma (N = 408,422), celiac disease (N = 15,283), Graves' disease (N = 458,620), Hashimoto thyroiditis (N = 395,640), primary biliary cirrhosis (PBC, N = 11,375), primary sclerosing cholangitis (PSC, N = 14,890), psoriasis vulgaris (N = 483,174), rheumatoid arthritis (RA, N = 417,256), systemic lupus erythematosus (SLE, N = 23,210), Type 1 diabetes (T1D, N = 520,580), inflammatory bowel disease (IBD, N = 34,652), and Sjogren's syndrome (SS, N = 407,746) were collected. Additionally, the latest summary-level data for TMDs (N = 228,812) were extracted from the FinnGen database. The overall effects of each immune traits were assessed via inverse-variance weighted (IVW), weighted median, and MR-Egger methods, and performed extensive sensitivity analyses. Finally, 731 immune cell phenotypes (N = 3,757) were analyzed for their mediating role in the significant causality.

Results

Univariable MR analyses revealed that genetically predicted RA (IVW OR: 1.12, 95% CI: 1.05-1.19, p < 0.001) and MS (IVW OR: 1.06, 95% CI: 1.03-1.10, p = 0.001) were associated with increased risk of TMDs. Two out of 731 immune cell phenotypes were identified as causal mediators in the associations of RA with TMDs, including "CD25++ CD8+ T cell % CD8+ T cell" (mediation proportion: 6.2%) and "CD3 on activated CD4 regulatory T cell" (5.4%). Additionally, "CD127 on granulocyte" mediated 10.6% of the total effect of MS on TMDs. No reverse directions, heterogeneity, and pleiotropy were detected in the analyses (p > 0.05).

Conclusion

This MR study provides new evidence regarding the causal impact of genetic predisposition to RA or MS on the increased risk of TMDs, potentially mediated by the modulation of immune cells. These findings highlight the importance for clinicians to pay more attention to patients with RA or MS when consulting for temporomandibular discomfort. The mediating role of specific immune cells is proposed but needs further investigation.

Macrophages and HLA-Class II Alleles in Multiple Sclerosis: Insights in Therapeutic Dynamics

Antigen presentation is a crucial mechanism that drives the T cell-mediated immune response and the development of Multiple Sclerosis (MS). Genetic alterations within the highly variable Major Histocompatibility Complex Class II (MHC II) have been proven to result in significant changes in the molecular basis of antigen presentation and the clinical course of patients with both Adult-Onset MS (AOMS) and Pediatric-Onset MS (POMS). Among the numerous polymorphisms of the Human Leucocyte Antigens (HLA), within MHC II complex, HLA-DRB1*15:01 has been labeled, in Caucasian ethnic groups, as a high-risk allele for MS due to the ability of its structure to increase affinity to Myelin Basic Protein (MBP) epitopes. This characteristic, among others, in the context of the trimolecular complex or immunological synapsis, provides the foundation for autoimmunity triggered by environmental or endogenous factors. As with all professional antigen presenting cells, macrophages are characterized by the expression of MHC II and are often implicated in the formation of MS lesions. Increased presence of M1 macrophages in MS patients has been associated both with progression and onset of the disease, each involving separate but similar mechanisms. In this critical narrative review, we focus on macrophages, discussing how HLA genetic alterations can promote dysregulation of this population's homeostasis in the periphery and the Central Nervous System (CNS). We also explore the potential interconnection in observed pathological macrophage mechanisms and the function of the diverse structure of HLA alleles in neurodegenerative CNS, seen in MS, by comparing available clinical with molecular data through the prism of HLA-immunogenetics. Finally, we discuss available and experimental pharmacological approaches for MS targeting the trimolecular complex that are based on cell phenotype modulation and HLA genotype involvement and try to reveal fertile ground for the potential development of novel drugs.

Exploring Inner Ear and Brain Connectivity through Perilymph Sampling for Early Detection of Neurological Diseases: A Provocative Proposal

Recent evidence shows that it is possible to identify the elements responsible for sensorineural hearing loss, such as pro-inflammatory cytokines and macrophages, by performing perilymph sampling. However, current studies have only focused on the diagnosis of such as otologic conditions. Hearing loss is a feature of certain neuroinflammatory disorders such as multiple sclerosis, and sensorineural hearing loss (SNHL) is widely detected in Alzheimer's disease. Although the environment of the inner ear is highly regulated, there are several communication pathways between the perilymph of the inner ear and cerebrospinal fluid (CSF). Thus, examination of the perilymph may help understand the mechanism behind the hearing loss observed in certain neuroinflammatory and neurodegenerative diseases. Herein, we review the constituents of CSF and perilymph, the anatomy of the inner ear and its connection with the brain. Then, we discuss the relevance of perilymph sampling in neurology. Currently, perilymph sampling is only performed during surgical procedures, but we hypothesize a simplified and low-invasive technique that could allow sampling in a clinical setting with the same ease as performing an intratympanic injection under direct visual check. The use of this modified technique could allow for perilymph sampling in people with hearing loss and neuroinflammatory/neurodegenerative disorders and clarify the relationship between these conditions; in fact, by measuring the concentration of neuroinflammatory and/or neurodegenerative biomarkers and those typically expressed in the inner ear in aging SNHL, it could be possible to understand if SNHL is caused by aging or neuroinflammation.

Wogonoside alleviates microglia-mediated neuroinflammation via TLR4/MyD88/NF-κB signaling axis after spinal cord injury

Wogonoside (WG) is a natural flavonoid extracted from Scutellariae Radix, recognized for its established anti-inflammatory properties. However, the role of WG in the context of neuroinflammation after spinal cord injury (SCI) remains inadequately elucidated. This study employed in silico, in vitro, and in vivo methodologies to investigate the impact of WG on microglia-mediated neuroinflammation after SCI. In the in silico experiment, we identified 15 potential target genes of WG associated with SCI. These genes were linked to the regulation of inflammatory response and immune defense. Molecular docking maps revealed toll-like receptor 4 as a molecular target for WG, demonstrating binding through a hydrogen bond (Lys263, Ser120). In lipopolysaccharide-stimulated BV2 cells and SCI mice, WG significantly attenuated microglial activation and facilitated a phenotype shift from M1 to M2. This was evidenced by the reversal of the increased expressions of Iba1, GFAP, and iNOS, as well as the decreased expression of Arg1. WG also suppressed the production of pro-inflammatory mediators (NO, TNF-α, IL-6, IL-1α, IL-1β, C1q). WG exerted these effects by suppressing the TLR4/MyD88/NF-κB signaling axis in microglia. Furthermore, by reducing levels of TNF-α, IL-1α, and C1q in supernatant of LPS-induced microglia, WG indirectly induced astrocytes change to A2 phenotype, evidenced by transcriptome sequencing result of primary mouse astrocytes. All these events above collectively created a favorable microenvironment, contributing to a significant alleviation of weight loss and neuronal damage at the lesion site of SCI mice. Our findings substantiate the efficacy of WG in mitigating neuroinflammation after SCI, thereby warranting further exploration.