Roles and regulation of microglia activity in multiple sclerosis: insights from animal models

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.

How microglia contribute to the induction and maintenance of neuropathic pain

Neuropathic pain is a debilitating condition caused by damage to the nervous system that results in changes along the pain pathway that lead to persistence of the pain sensation. Unremitting pain conditions are associated with maladaptive plasticity, disruption of neuronal activity that favours excitation over inhibition, and engagement of immune cells. The substantial progress made over the last two decades in the neuroimmune interaction research area points to a mechanistic role of spinal cord microglia, which are resident immune cells of the CNS. Microglia respond to and modulate neuronal activity during establishment and persistence of neuropathic pain states, and microglia-neuron pathways provide targets that can be exploited to attenuate abnormal neuronal activity and provide pain relief.

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.

Microglia endotoxin tolerance is retained after enforced repopulation

Microglia are crucial for CNS homeostasis and are involved in a wide range of neurodegenerative and neuroinflammatory diseases. Systemic inflammation and infections can contribute to neurodegeneration later in life by affecting microglia. Like other innate immune cells, microglia can develop innate immune memory (IMM) in response to an inflammatory challenge, altering their response to subsequent stimuli. IMM can ameliorate or worsen CNS pathology, but it is unclear if IMM can be reversed to restore microglia functions. Here, we investigated whether microglia depletion-repopulation by inhibition of the colony-stimulating factor 1 receptor with BLZ945 reversed LPS-induced endotoxin tolerance in mice. Repopulated microglia displayed a reduced expression of homeostatic genes and genes related to mitochondrial respiration and TCA cycle metabolism and an increased expression of immune effector and activation genes. Nonetheless the blunted inflammatory gene response after LPS-preconditioning was retained after a depletion-repopulation cycle. Our study highlights the persistence of endotoxin tolerance in microglia after a depletion-repopulation cycle which might impact the potential effectiveness of strategies targeted at microglia depletion for clinical applications.

Experimental autoimmune encephalomyelitis pathogenesis alters along animal age: impact of S100B expression

Multiple Sclerosis (MS) is the leading inflammatory and non-traumatic cause of disability in young adults, with late-onset MS emerging in middle-aged patients often resulting in poorer treatment responses and worse prognoses. The calcium-binding protein S100B is elevated in MS patients, and its targeting has shown promise in reducing disease severity in experimental autoimmune encephalomyelitis (EAE) models. However, most studies on MS pathology have focused on young animal models, leaving a gap in understanding the effects of age and S100B ablation on disease progression throughout the lifespan. This study aimed to characterize EAE in mice of different ages, examining demyelination, inflammation, and immune responses to determine whether S100B ablation could mitigate MS pathogenesis across the lifespan. EAE was induced in six cohorts of C57BL/6 mice: young adults (3 months), older adults (6 months), and middle-aged (12 months), including corresponding S100B knockout (KO) groups, followed for 23 days. Upon sacrifice, spinal cords were assessed via immunohistochemistry and Real-Time qPCR, while splenocytes were analyzed for immune cell characterization. Results indicated a more severe disease course in 12-month-old mice, marked by increased gliosis, inflammation, and impaired microglial phagocytic activity. Notably, S100B absence reduced gliosis and inflammatory markers across all ages, with 12-month-old S100B KO mice showing increased regulatory T cells. These findings highlight the exacerbating role of age and elevated S100B in MS progression, underscoring the importance of identifying age-specific MS markers and therapeutic targets.

Neuroprotective effects of ghrelin in cuprizone-induced rat model of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory central nervous system disease characterized by demyelination and axonal loss and is the main cause of non-traumatic neurological disability in young adults. Although there are several treatment approaches to manage the disease, there is no definitive cure for multiple sclerosis. Inflammation and oxidative stress are known to play important roles in the pathophysiology of MS. Ghrelin, a peptide secreted by the stomach, is reported to have neuroprotective properties through several pathways, including attenuating oxidative stress and inflammation. In the present study cuprizone (CPZ)-induced model of MS was used in Wistar albino rats to study the possible anti-inflammatory, antioxidant and neuroprotective effects of ghrelin. Rats were randomly divided into six groups: Control groups (Control35 and Control-S42), demyelination group, remyelination group, remyelination + ghrelin (20 µg/kg) group and remyelination + ghrelin (40 µg/kg) group. Y maze test was performed on the rats on their last day of the experiment. Oxidative stress and inflammatory parameters were investigated in brain using commercial kits by enzyme-linked immunosorbent assay (ELISA). Luxol fast blue (LFB) and hematoxylen&eosin (H&E) staining were performed in brain tissues. CPZ leads to a significant decrease in glutathione peroxidase (GSH-Px) levels and myelin content and a significant increase in malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-ɑ), interleukin- 6 (IL- 6) levels, the number of lymphatic cells and inflammatory cells. A significant increase in the antioxidant parameter levels and a significant decrease in MDA levels were found in the ghrelin treated groups (p < 0.05). CPZ leads to irregular, fragmented, demyelinating nerve fibers. A more significant remyelination was observed in the ghrelin treated groups compared to the other groups (p < 0.05). In conclusion, ghrelin treatment showed neuroprotective and antioxidant properties and reduced demyelination in the CPZ-induced rat model of multiple sclerosis.

Exploring Human Brain Metabolism via Genome-Scale Metabolic Modeling with Highlights on Multiple Sclerosis

Cerebral dysfunctions give rise to a wide range of neurological diseases due to the structural and functional complexity of the human brain stemming from the interactive cellular metabolism of its specific cells, including neurons and glial cells. In parallel with advances in isolation and measurement technologies, genome-scale metabolic models (GEMs) have become a powerful tool in the studies of systems biology to provide critical insights into the understanding of sophisticated eukaryotic systems. In this study, brain cell-specific GEMs were reconstructed for neurons, astrocytes, microglia, oligodendrocytes, and oligodendrocyte precursor cells by integrating single-cell RNA-seq data and global Human1 via a task-driven integrative network inference for tissues (tINIT) algorithm. Then, intercellular reactions among neurons, astrocytes, microglia, and oligodendrocytes were added to generate a combined brain model, iHumanBrain2690. This brain network was used in the prediction of metabolic alterations in glucose, ketone bodies, oxygen change, and reporter metabolites. Glucose supplementation increased the subsystems' activities in glycolysis, and ketone bodies elevated those in the TCA cycle and oxidative phosphorylation. Reporter metabolite analysis identified L-carnitine and arachidonate as the top reporter metabolites in gray and white matter microglia in multiple sclerosis (MS), respectively. Carbamoyl-phosphate was found to be the top reporter metabolite in primary progressive MS. Taken together, single and integrated iHumanBrain2690 metabolic networks help us elucidate complex metabolism in brain physiology and homeostasis in health and disease.

Microglia regulate myelin clearance and cholesterol metabolism after demyelination via interferon regulatory factor 5

Interferon regulatory factor 5 (IRF5) is a transcription factor that plays a role in orchestrating innate immune responses, particularly in response to viral infections. Notably, IRF5 has been identified as a microglia risk gene linked to multiple sclerosis (MS), but its specific role in MS pathogenesis remains unclear. Through the use of Irf5-/- mice, our study uncovers a non-canonical function of IRF5 in MS recovery. Irf5-/- mice exhibited increased damage in an experimental autoimmune encephalomyelitis (EAE) model and demonstrated impaired oligodendrocyte recruitment into the lesion core following lysolecithin-induced demyelination. Transcriptomic and lipidomic analyses revealed that IRF5 has a role in microglia-mediated myelin phagocytosis, lipid metabolism, and cholesterol homeostasis. Indeed, Irf5-/- microglia phagocytose myelin, but myelin debris is not adequately degraded, leading to an accumulation of lipid droplets, cholesterol esters, and cholesterol crystals within demyelinating lesions. This abnormal buildup can hinder remyelination processes. Importantly, treatments that promote cholesterol transport were found to reduce lipid droplet accumulation and mitigate the exacerbated damage in Irf5-/- mice with EAE. Altogether, our study identified the antiviral transcription factor IRF5 as a key transcriptional regulator of lipid degradation and cholesterol homeostasis and suggest that loss of IRF5 function leads to pathogenic lipid accumulation in microglia, thereby obstructing remyelination. These data and the fact that Irf5 polymorphisms are significantly associated with MS, highlight IRF5 as a potential therapeutic target to promote regenerative responses.

Male-Dominant Spinal Microglia Contribute to Neuropathic Pain by Producing CC-Chemokine Ligand 4 Following Peripheral Nerve Injury

Recent studies have revealed marked sex differences in pathophysiological roles of spinal microglia in neuropathic pain, with microglia contributing to pain exacerbation exclusively in males. However, the characteristics of pain-enhancing microglia, which are more prominent in males, remain poorly understood. Here, we reanalyzed a previously published single-cell RNA sequencing dataset and identified a microglial subpopulation that significantly increases in the spinal dorsal horn (SDH) of male mice following peripheral nerve injury. CC-chemokine ligand 4 (CCL4) was highly expressed in this subpopulation and its mRNA levels were increased in the SDH after partial sciatic nerve ligation (PSL) only in male mice. Notably, CCL4 expression was reduced in male mice following microglial depletion, indicating that microglia are the primary source of CCL4. Intrathecal administration of maraviroc, an inhibitor of the CCL4-CC-chemokine receptor 5 (CCR5) signaling pathway, after PSL, significantly suppressed mechanical allodynia only in male mice. Furthermore, intrathecal administration of CCL4 induced mechanical allodynia in both sexes, accompanied by increased expression of c-fos, a neuronal excitation marker, in the SDH. These findings highlight a sex-biased difference in the gene expression profile of spinal microglia following peripheral nerve injury, with elevated CCL4 expression in male mice potentially contributing to pain exacerbation.

Genetically Programmed Single-Component Protein Hydrogel for Spinal Cord Injury Repair

Protein self-assembly allows for the formation of diverse supramolecular materials from relatively simple building blocks. In this study, a single-component self-assembling hydrogel is developed using the recombinant protein CsgA, and its successful application for spinal cord injury repair is demonstrated. Gelation is achieved by the physical entanglement of CsgA nanofibrils, resulting in a self-supporting hydrogel at low concentrations (≥5 mg mL-1). By leveraging the programmability of the CsgA gene sequence, the bioactive hydrogel is enhanced by fusing functional peptide GHK. GHK is recognized for its anti-inflammatory, antioxidant, and neurotrophic factor-stimulating properties, making it a valuable addition to the hydrogel for spinal cord injury repair applications. In vitro experiments demonstrate that the CsgA-GHK hydrogel can modulate microglial M2 polarization, promote neuronal differentiation of neural stem cells, and inhibit astrocyte differentiation. Additionally, the hydrogel shows efficacy in alleviating inflammation and promotes neuronal regeneration at the injury site, leading to significant functional recovery in a rat model with compression injury spinal cord cavity. These findings lay the groundwork for developing a modular design platform for recombinant CsgA protein hydrogels in tissue repair applications.

Multiomic single-cell profiling identifies critical regulators of postnatal brain

Human brain development spans from embryogenesis to adulthood, with dynamic gene expression controlled by cell-type-specific cis-regulatory element activity and three-dimensional genome organization. To advance our understanding of postnatal brain development, we simultaneously profiled gene expression and chromatin accessibility in 101,924 single nuclei from four brain regions across ten donors, covering five key postnatal stages from infancy to late adulthood. Using this dataset and chromosome conformation capture data, we constructed enhancer-based gene regulatory networks to identify cell-type-specific regulators of brain development and interpret genome-wide association study loci for ten main brain disorders. Our analysis connected 2,318 cell-specific loci to 1,149 unique genes, representing 41% of loci linked to the investigated traits, and highlighted 55 genes influencing several disease phenotypes. Pseudotime analysis revealed distinct stages of postnatal oligodendrogenesis and their regulatory programs. These findings provide a comprehensive dataset of cell-type-specific gene regulation at critical timepoints in postnatal brain development.

Betaine alleviates cerebellar endoplasmic reticulum stress and oxidative imbalance in a cuprizone model of multiple sclerosis in rat

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system, especially the cerebellum, with numerous physical and mental symptoms. Oxidative stress caused by inflammation can play a role in the occurrence of this disease. Betaine, a natural methyl donor compound, has potent neuroprotective effects. Here, we investigated the effects of betaine on motor behavior, cerebellar histological changes, oxidative stress response, and endoplasmic reticulum stress in a cuprizone (CPZ)-induced multiple sclerosis model in male rats. Twenty Wistar adult male rats were randomly divided into four groups including control, MS, betaine-treated MS, and betaine groups. MS was induced by feeding animals with rodent chow containing 0.5% CPZ for 12 weeks. Betaine was daily administrated as 1% in drinking water for the last 6 weeks. The motor behavioral performance was evaluated by open field, rotarod, and reverse basket tests. Histological analysis of the cerebellum was performed by hematoxylin and eosin (H&E) and Cresyl violet (Nissl) staining. Oxidative stress factors (GSH, GSSG, GPX, GR, and GT) were assessed in the experimental groups and finally, the expression of ERS-associated proteins was measured using western blot analysis. Data showed that treatment with betaine could effectively prevent and reverse the adverse behavioral manifestation compared with the MS group. Betaine treatment protected cerebellar demyelination and neuron and Purkinje cell degeneration against CPZ-induced demyelination. Betaine attenuated the protein levels of ESR-related proteins in the cerebellum of MS rats and similarly increased the level of enzymes related to antioxidants in the cerebellum. Therefore, our results suggest that oral administration of betaine may be used as a novel adjunct therapy against cerebellar dysfunctions in an animal model of MS.

Genetic Analysis of Retinal Cell Types in Neuropsychiatric Disorders

Importance

As an accessible part of the central nervous system, the retina provides a unique window to study pathophysiological mechanisms of brain disorders in humans. Imaging and electrophysiological studies have revealed retinal alterations across several neuropsychiatric and neurological disorders, but it remains largely unclear which specific cell types and biological mechanisms are involved.

Objective

To determine whether specific retinal cell types are affected by genomic risk for neuropsychiatric and neurological disorders and to explore the mechanisms through which genomic risk converges in these cell types.

Design, Setting, and Participants

This genetic association study combined findings from genome-wide association studies in schizophrenia, bipolar disorder, major depressive disorder, multiple sclerosis, Parkinson disease, Alzheimer disease, and stroke with retinal single-cell transcriptomic datasets from humans, macaques, and mice. To identify susceptible cell types, Multi-Marker Analysis of Genomic Annotation (MAGMA) cell-type enrichment analyses were applied and subsequent pathway analyses performed. The cellular top hits were translated to the structural level using retinal optical coherence tomography (acquired between 2009 and 2010) and genotyping data in the large population-based UK Biobank cohort study. Data analysis was conducted between 2022 and 2024.

Main Outcomes and Measures

Cell type-specific enrichment of genetic risk loading for neuropsychiatric and neurological disorder traits in the gene expression profiles of retinal cells.

Results

Expression profiles of amacrine cells (interneurons within the retina) were robustly enriched in schizophrenia genetic risk across mammalian species and in different developmental stages. This enrichment was primarily driven by genes involved in synapse biology. Moreover, expression profiles of retinal immune cell populations were enriched in multiple sclerosis genetic risk. No consistent cell-type associations were found for bipolar disorder, major depressive disorder, Parkinson disease, Alzheimer disease, or stroke. On the structural level, higher polygenic risk for schizophrenia was associated with thinning of the ganglion cell inner plexiform layer, which contains dendrites and synaptic connections of amacrine cells (B, -0.09; 95% CI, -0.16 to -0.03; P = .007; n = 36 349; mean [SD] age, 57.50 [8.00] years; 19 859 female [54.63%]). Higher polygenic risk for multiple sclerosis was associated with increased thickness of the retinal nerve fiber layer (B, 0.06; 95% CI, 0.02 to 0.10; P = .007; n = 36 371; mean [SD] age, 57.51 [8.00] years; 19 843 female [54.56%]).

Conclusions and Relevance

This study provides novel insights into the cellular underpinnings of retinal alterations in neuropsychiatric and neurological disorders and highlights the retina as a potential proxy to study synaptic pathology in schizophrenia.

Prevention of motor relapses and associated trigeminal pain in experimental autoimmune encephalomyelitis by reducing neuroinflammation with a purple corn extract enriched in anthocyanins

Multiple sclerosis (MS) is the leading cause of disability in young adults, with about 2.5-3 million cases currently diagnosed. Pain is a common comorbid symptom of MS, and develops independently from motor impairments. Currently utilized drugs bear severe side effects; thus, new therapeutic strategies are needed, and nutraceutical supplements represent innovative and safe opportunities. We have selected a variety of anthocyanin-enriched purple corn, from which a water-soluble extract (Red extract) has been obtained and administered to male rats exposed to experimental autoimmune encephalomyelitis (EAE). Animals developed relapsing-remitting motor symptoms, accompanied by early onset trigeminal allodynia. The preventive administration of Red extract facilitated the remission of motor symptoms, prevented the development of relapses, and delayed and reduced the development of EAE-associated trigeminal pain. An overall inhibition of neuroinflammation, blunted microgliosis and astrogliosis, activation of autophagy and reduced immune cell infiltration in the brainstem, cervical and lumbar spinal cord were observed. Yellow corn extract, lacking anthocyanins, had no behavioral effects, despite a limited anti-inflammatory action. Therapeutic Red extract administration did not affect EAE motor symptoms, only partially reduced the development of trigeminal pain but maintained its ability to reduce neuroinflammation and glial cell activation and to promote autophagy. Overall, our data suggest that a nutraceutical supplement from anthocyanin-enriched purple corn represents an interesting option to limit the development of motor relapses and the chronicization of multiple sclerosis-associated pain, through the mitigation of neuroinflammation, of the infiltration of immune cells and the promotion of autophagy.

EGFL7: An emerging biomarker with great therapeutic potential

EGFL7 is a factor involved in the regulation of various essential biological mechanisms. Endothelial cells and neurons secrete the EGFL7 protein into the extracellular matrix, where it interacts with other matrix proteins, thereby regulating several important signaling pathways. To date, extensive in vitro and in vivo studies have illuminated the central role of EGFL7 in governing major biological processes involving blood vessels and the central nervous system. Notably, EGFL7 has also emerged as a key factor in a spectrum of diseases including cancer, stroke, multiple sclerosis and preeclampsia. Its influence on various diseases and multiple regulatory pathways highlights EGFL7 as an emerging biomarker and therapeutic target. Thus, the multifaceted regulatory functions of EGFL7 will be discussed in the physiological context before delving into its involvement in the progression of different diseases. Finally, the review will provide an insight into the broad therapeutic potential of EGFL7 by describing its role as a powerful biomarker and discussing potential strategies to therapeutically target EGFL7 function in a plethora of human diseases.

Gemistocytic tumor cells programmed for glial scarring characterize T cell confinement in IDH-mutant astrocytoma

Isocitrate dehydrogenase 1/2 mutant (IDHmt) astrocytoma is considered a T cell-deprived tumor, yet little is known regarding the phenotypes underlying T cell exclusion. Using bulk, single nucleus and spatial RNA and protein profiling, we demonstrate that a distinct spatial organization underlies T cell confinement to the perivascular space (T cell cuff) in IDHmt astrocytoma. T cell cuffs are uniquely characterized by a high abundance of gemistocytic tumor cells (GTC) in the surrounding stroma. Integrative analysis shows that GTC-high tumors are enriched for lymphocytes and tumor associated macrophages (TAM) and express immune cell migration and activation programs. Specifically, GTCs constitute a distinct sub-cluster of the astrocyte-like tumor cell state that co-localizes with immune reactive TAMs. Neighboring GTCs and TAMs express receptor-ligand pairs characteristic of reactive astrogliosis and glial scarring, such as SPP1/CD44 and IL-1β/IL1R1. Collectively, we reveal that T cell confinement in IDHmt astrocytomas associates with GTC-TAM networks that mimic glial scarring mechanisms.

Acupoint catgut embedding alleviates experimental autoimmune encephalomyelitis by modulating neuroinflammation and potentially inhibiting glia activation through JNK and ERK pathways

Background

Acupoint catgut embedding (ACE) is a traditional Chinese medicine technique commonly used for managing various disorders, including chronic inflammatory pain and allergic asthma. Despite its growing use, the neuroimmunological mechanisms underlying ACE treatment effects remain unclear.

Methods

This study investigated the roles and potential mechanisms of the effects of ACE in treating experimental autoimmune encephalomyelitis (EAE), a frequently used animal model of autoimmune neuroinflammation. The effects of ACE treatment were evaluated by monitoring body weight and EAE severity scores. Behavioral tests, histopathological analysis, ELISA, and flow cytometry were conducted to assess the therapeutic efficacy of ACE. RNA sequencing was performed to uncover ACE-associated transcriptional signatures in the spinal cords of EAE mice.

Results

The results were validated through western blotting, qRT-PCR, and immunofluorescence (IF) staining. In ACE-treated mice, EAE disease severity was significantly ameliorated, along with improvements in anxiety-like behaviors and reduced inflammation and demyelination. The ACE treatment restored immune imbalance in the EAE mice by decreasing Th17 and Th1 cells, while increasing Treg cells in peripheral immune organs and reducing serum inflammatory cytokine levels. RNA sequencing revealed significant suppression of the genes and pathways associated with reactive microglial and astrocytic activation, corroborated by IF studies. Additionally, ACE treatment could suppress the ERK and JNK signaling pathways at both RNA and protein levels.

Conclusion

These findings confirm the protective role of ACE in mitigating EAE symptoms by modulating microglial and astrocytic activity and regulating inflammatory cytokines.

Ontogenetic Neuroimmune Changes Following Prenatal Alcohol Exposure: Implications for Neurobehavioral Function

This chapter reviews the enduring effects of prenatal alcohol exposure (PAE) on neuroimmune function across the lifespan, including discussion of associated neurobehavioral alterations. Alcohol has potent teratogenic effects, with a large body of work linking PAE to perturbations in neuroimmune function. These PAE-related neuroimmune disturbances may have downstream effects on neurobehavioral function given the critical role of the neuroimmune system in central nervous system development. The neuroimmune system matures over time, playing distinct roles depending on the developmental processes occurring within that maturational stage. This chapter thus takes an ontogenetic approach to understanding how PAE induces unique neuroimmune changes across the lifespan, beginning with a review of changes in early life before moving into adolescence and ending in adulthood. The focus will be on work utilizing rodent models, which allow for more tightly controlled conditions than are possible in human research. The chapter concludes with a discussion of possible mechanisms underlying the developmental changes in neuroimmune function following PAE, with a specific focus on the role of the gut microbiota.

TNFR2 signaling in oligodendrocyte precursor cells suppresses their immune-inflammatory function and detrimental microglia activation in CNS demyelinating disease

Multiple Sclerosis (MS) is a chronic degenerative disease of the central nervous system (CNS) characterized by inflammation, demyelination, and progressive neurodegeneration. These processes, combined with the failure of reparative remyelination initiated by oligodendrocyte precursor cells (OPCs), lead to irreversible neurological impairment. The cytokine tumor necrosis factor (TNF) has been implicated in CNS repair via activation of its cognate receptor TNFR2 in glia. Here, we demonstrate the important role of TNFR2 in regulating OPC function in vivo during demyelinating disease, and that TNFR2 expressed in OPCs modulates OPC-microglia interactions. In PdgfrαCreERT:Tnfrsf1bfl/fl:Eyfp mice with selective TNFR2 ablation in OPCs, we observed an earlier onset and disease peak in experimental autoimmune encephalomyelitis (EAE). This was associated with accelerated immune cell infiltration and increased microglia activation in the spinal cord. Similarly, PdgfrαCreERT:Tnfrsf1bfl/fl:Eyfp mice showed rapid and increased microglia reactivity compared to control mice in the corpus callosum after cuprizone-induced demyelination, followed by chronic reduction in the number of mature myelinating oligodendrocytes (OLs). With EAE and cuprizone models combined, we uncovered that TNFR2 does not have a cell autonomous role in OPC differentiation, but may be important for survival of newly formed mature OLs. Finally, using an in vitro approach, we demonstrated that factors released by Tnfrsf1b ablated OPCs drove microglia to develop an exacerbated "foamy" phenotype when incubated with myelin-rich spinal cord homogenate, aberrantly increasing lysosomal lipid accumulation. Together, our data indicate that TNFR2 signaling in OPCs is protective by dampening their immune-inflammatory activation and by suppressing neurotoxic microglia reactivity. This suggests that boosting TNFR2 activation or its downstream cascades could be an effective strategy to restore OPC reparative capacity in neuroimmune and demyelinating disease.

Hidden role of microglia during neurodegenerative disorders and neurocritical care: A mitochondrial perspective

The incidence of aging-related neurodegenerative disorders and neurocritical care diseases is increasing worldwide. Microglia, the main inflammatory cells in the brain, could be potential viable therapeutic targets for treating neurological diseases. Interestingly, mitochondrial functions, including energy metabolism, mitophagy and transfer, fission and fusion, and mitochondrial DNA expression, also change in activated microglia. Notably, mitochondria play an active and important role in the pathophysiology of neurodegenerative disorders and neurocritical care diseases. This review briefly summarizes the current knowledge on mitochondrial dysfunction in microglia in neurodegenerative disorders and neurocritical care diseases and comprehensively discusses the prospects of the application of neurological injury prevention and treatment targets by mitochondria.

Promoting remyelination in central nervous system diseases: Potentials and prospects of natural products and herbal medicine

Myelin damage is frequently associated with central nervous system (CNS) diseases and is a critical factor influencing neurological function and disease prognosis. Nevertheless, the majority of current treatments for the CNS concentrate on gray matter injury and repair strategies, while clinical interventions specifically targeting myelin repair remain unavailable. In recent years, natural products and herbal medicine have achieved considerable progress in the domain of myelin repair, given their remarkable curative effect and low toxic side effects, demonstrating significant therapeutic potential. In this review, we present a rather comprehensive account of the mechanisms underlying myelin formation, injury, and repair, with a particular emphasis on the interactions between oligodendrocytes and other glial cells. Furthermore, we summarize the natural products and herbal medicine currently employed in remyelination along with their mechanisms of action, highlighting the potential and challenges of certain natural compounds to enhance myelin repair. This review aims to facilitate the expedited development of innovative therapeutics derived from natural products and herbal medicine and furnish novel insights into myelin repair in the CNS.

Brain-immune interactions: implication for cognitive impairments in Alzheimer's disease and autoimmune disorders

Progressive memory loss and cognitive dysfunction, encompassing deficits in learning, memory, problem solving, spatial reasoning, and verbal expression, are characteristics of Alzheimer's disease and related dementia. A wealth of studies has described multiple roles of the immune system in the development or exacerbation of dementia. Individuals with autoimmune disorders can also develop cognitive dysfunction, a phenomenon termed "autoimmune dementia." Together, these findings underscore the pivotal role of the neuroimmune axis in both Alzheimer's disease and related dementia and autoimmune dementia. The dynamic interplay between adaptive and innate immunity, both in and outside the brain, significantly affects the etiology and progression of these conditions. Multidisciplinary research shows that cognitive dysfunction arises from a bidirectional relationship between the nervous and immune systems, though the specific mechanisms that drive cognitive impairments are not fully understood. Intriguingly, this reciprocal regulation occurs at multiple levels, where neuronal signals can modulate immune responses, and immune system-related processes can influence neuronal viability and function. In this review, we consider the implications of autoimmune responses in various autoimmune disorders and Alzheimer's disease and explore their effects on brain function. We also discuss the diverse cellular and molecular crosstalk between the brain and the immune system, as they may shed light on potential triggers of peripheral inflammation, their effect on the integrity of the blood-brain barrier, and brain function. Additionally, we assess challenges and possibilities associated with developing immune-based therapies for the treatment of cognitive decline.

Fenebrutinib, a Bruton's tyrosine kinase inhibitor, blocks distinct human microglial signaling pathways

BACKGROUND

Bruton's tyrosine kinase (BTK) is an intracellular signaling enzyme that regulates B-lymphocyte and myeloid cell functions. Due to its involvement in both innate and adaptive immune compartments, BTK inhibitors have emerged as a therapeutic option in autoimmune disorders such as multiple sclerosis (MS). Brain-penetrant, small-molecule BTK inhibitors may also address compartmentalized neuroinflammation, which is proposed to underlie MS disease progression. BTK is expressed by microglia, which are the resident innate immune cells of the brain; however, the precise roles of microglial BTK and impact of BTK inhibitors on microglial functions are still being elucidated. Research on the effects of BTK inhibitors has been limited to rodent disease models. This is the first study reporting effects in human microglia.

METHODS

Here we characterize the pharmacological and functional properties of fenebrutinib, a potent, highly selective, noncovalent, reversible, brain-penetrant BTK inhibitor, in human microglia and complex human brain cell systems, including brain organoids.

RESULTS

We find that fenebrutinib blocks the deleterious effects of microglial Fc gamma receptor (FcγR) activation, including cytokine and chemokine release, microglial clustering and neurite damage in diverse human brain cell systems. Gene expression analyses identified pathways linked to inflammation, matrix metalloproteinase production and cholesterol metabolism that were modulated by fenebrutinib treatment. In contrast, fenebrutinib had no significant impact on human microglial pathways linked to Toll-like receptor 4 (TLR4) and NACHT, LRR and PYD domains-containing protein 3 (NLRP3) signaling or myelin phagocytosis.

CONCLUSIONS

Our study enhances the understanding of BTK functions in human microglial signaling that are relevant to MS pathogenesis and suggests that fenebrutinib could attenuate detrimental microglial activity associated with FcγR activation in people with MS.

CX3CR1+/UCHL1+ microglial extracellular vesicles in blood: a potential biomarker for multiple sclerosis

In neuroinflammation, distinguishing microglia from macrophages and identifying microglial-specific biomarkers in peripheral blood pose significant challenges. This study comprehensively profiled the extracellular vesicles (EVs) of microglia and macrophages, respectively, revealing co-expressed EVs with UCHL1 and CX3CR1 as EVs derived specifically from microglia in human blood. After extensive validation, using optimized nano flow cytometry, we evaluated plasma CX3CR1+/UCHL1+ EVs across clinical cohorts [multiple sclerosis (MS), HTLV-1 associated myelopathy (HAM), Alzheimer's disease (AD), and Parkinson's disease (PD)], along with established neurodegenerative markers (NMDAR2A and NFL). The findings discovered a notable rise in CX3CR1+/UCHL1+ EVs in MS, particularly heightened in HAM, in contrast to controls. Conversely, AD and PD exhibited unaltered or diminished levels of microglial EVs. An integrated model of CX3CR1+/UCHL1+, NMDAR2A+, and NFL+ EVs demonstrated promising diagnostic potential for distinguishing MS from controls and HAM. As to the disease duration, CX3CR1+/UCHL1+ EVs increased in the initial five years of MS, stabilizing thereafter, whereas NMDAR2A+ and NFL+ EVs remained stable initially but increased significantly in the subsequent five years, suggesting their correlation with disease duration. This study uncovers unique blood microglial EVs with potential as biomarkers for MS diagnosis, differentiation from HAM, and correlation with disease duration.

The role of dopamine in the modulation of monocyte-induced Th17- and Th1-immune response in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) with autoimmune mechanism of development. The investigation of neuroimmune interaction is one of the most developing directions in MS pathogenesis study. Catecholamines are direct mediators of this interaction and can be involved in the pathogenesis of MS by modulating cells of both innate and adaptive immune systems. The aim of this study was to investigate the influence of dopamine and norepinephrine on the ability of monocytes of patients with relapsing-remitting MS, to induce Th17- and Th1-immune response, which play a crucial role in the autoimmunity of the CNS. We found, that both dopamine and norepinephrine modulate the production of Th17- (IL-23, IL-1β, and IL-6) and Th1-promoting (IL-12p70) cytokines by activated peripheral blood mononuclear cells or CD14+ monocytes in patients with MS and in healthy subjects. We also found the inhibitory effect of dopamine and norepinephrine on monocyte-induced production of IL-17 and IFN-γ by autologous CD4+ T-cells in both groups. Finally, the multidirectional role of D1- and D2-like dopaminergic receptors in the modulatory effect of dopamine on the ability of CD14+ monocytes to activate CD4+ T-cells was established, expanding the potential role of dopamine in the neuroimmune interaction.

The role of macrophage plasticity in neurodegenerative diseases

Tissue-resident macrophages and recruited macrophages play pivotal roles in innate immunity and the maintenance of brain homeostasis. Investigating the involvement of these macrophage populations in eliciting pathological changes associated with neurodegenerative diseases has been a focal point of research. Dysregulated states of macrophages can compromise clearance mechanisms for pathological proteins such as amyloid-β (Aβ) in Alzheimer's disease (AD) and TDP-43 in Amyotrophic lateral sclerosis (ALS). Additionally, recent evidence suggests that abnormalities in the peripheral clearance of pathological proteins are implicated in the pathogenesis and progression of neurodegenerative diseases. Furthermore, numerous genome-wide association studies have linked genetic risk factors, which alter the functionality of various immune cells, to the accumulation of pathological proteins. This review aims to unravel the intricacies of macrophage biology in both homeostatic conditions and neurodegenerative disorders. To this end, we initially provide an overview of the modifications in receptor and gene expression observed in diverse macrophage subsets throughout development. Subsequently, we outlined the roles of resident macrophages and recruited macrophages in neurodegenerative diseases and the progress of targeted therapy. Finally, we describe the latest advances in macrophage imaging methods and measurement of inflammation, which may provide information and related treatment strategies that hold promise for informing the design of future investigations and therapeutic interventions.

Microglia specific alternative splicing alterations in multiple sclerosis

Several aberrant alternative splicing (AS) events and their regulatory mechanisms are widely recognized in multiple sclerosis (MS). Yet the cell-type specific AS events have not been extensively examined. Here we assessed the diversity of AS events using web-based RNA-seq data of sorted CD15-CD11b+ microglia in white matter (WM) region from 10 patients with MS and 11 control subjects. The GSE111972 dataset was downloaded from GEO and ENA databases, aligned to the GRCh38 reference genome from ENSEMBL via STAR. rMATS was used to assess five types of AS events, alternative 3'SS (A3SS), alternative 5'SS (A5SS), skipped exon (SE), retained intron (RI) and mutually exclusive exons (MXE), followed by visualizing with rmats2sashimiplot and maser. Differential genes or transcripts were analyzed using the limma R package. Gene ontology (GO) analysis was performed with the clusterProfiler R package. 42,663 raw counts of AS events were identified and 132 significant AS events were retained based on the filtered criteria: 1) average coverage >10 and 2) delta percent spliced in (ΔPSI) >0.1. SE was the most common AS event (36.36%), followed by MXE events (32.58%), and RI (18.94%). Genes related to telomere maintenance and organization primarily underwent SE splicing, while genes associated with protein folding and mitochondrion organization were predominantly spliced in the MXE pattern. Conversely, genes experiencing RI were enriched in immune response and immunoglobulin production. In conclusion, we identified microglia-specific AS changes in the white matter of MS patients, which may shed light on novel pathological mechanisms underlying MS.

Exploring the clinical transition of engineered exosomes designed for intracellular delivery of therapeutic proteins

Extracellular vesicles, particularly exosomes, have emerged as promising drug delivery systems owing to their unique advantages, such as biocompatibility, immune tolerability, and target specificity. Various engineering strategies have been implemented to harness these innate qualities, with a focus on enhancing the pharmacokinetic and pharmacodynamic properties of exosomes via payload loading and surface engineering for active targeting. This concise review outlines the challenges in the development of exosomes as drug carriers and offers insights into strategies for their effective clinical translation. We also highlight preclinical studies that have successfully employed anti-inflammatory exosomes and suggest future directions for exosome therapeutics. These advancements underscore the potential for integrating exosome-based therapies into clinical practice, heralding promise for future medical interventions.

Cellular Therapy in Experimental Autoimmune Encephalomyelitis as an Adjuvant Treatment to Translate for Multiple Sclerosis

This study aims to evaluate and compare cellular therapy with human Wharton's jelly (WJ) mesenchymal stem cells (MSCs) and neural precursors (NPs) in experimental autoimmune encephalomyelitis (EAE), a preclinical model of Multiple Sclerosis. MSCs were isolated from WJ by an explant technique, differentiated to NPs, and characterized by cytometry and immunocytochemistry analysis after ethical approval. Forty-eight rats were EAE-induced by myelin basic protein and Freund's complete adjuvant. Forty-eight hours later, the animals received intraperitoneal injections of 250 ng/dose of Bordetella pertussis toxin. Fourteen days later, the animals were divided into the following groups: a. non-induced, induced: b. Sham, c. WJ-MSCs, d. NPs, and e. WJ-MSCs plus NPs. 1 × 105. Moreover, the cells were placed in a 10 µL solution and injected via a stereotaxic intracerebral ventricular injection. After ten days, the histopathological analysis for H&E, Luxol, interleukins, and CD4/CD8 was carried out. Statistical analyses demonstrated a higher frequency of clinical manifestation in the Sham group (15.66%) than in the other groups; less demyelination was seen in the treated groups than the Sham group (WJ-MSCs, p = 0.016; NPs, p = 0.010; WJ-MSCs + NPs, p = 0.000), and a lower cellular death rate was seen in the treated groups compared with the Sham group. A CD4/CD8 ratio of <1 showed no association with microglial activation (p = 0.366), astrocytes (p = 0.247), and cell death (p = 0.577) in WJ-MSCs. WJ-MSCs and NPs were immunomodulatory and neuroprotective in cellular therapy, which would be translated as an adjunct in demyelinating diseases.

Exploring potential developmental origins of common neurodegenerative disorders

In the United States, it is now estimated that 6.7 million people over the age of 65 are afflicted by Alzheimer's disease (AD), over 1 million people are living with Parkinson's disease (PD), and over 200 000 have or are at risk for developing Huntington's disease (HD). All three of these neurodegenerative diseases result in the ultimate death of distinct neuronal subtypes, and it is widely thought that age-related damage is the single biggest contributing factor to this neuronal death. However, recent studies are now suggesting that developmental defects during early neurogenesis could also play a role in the pathology of neurodegenerative diseases. Loss or overexpression of proteins associated with HD, PD, and AD also result in embryonic phenotypes but whether these developmental defects slowly unmask over time and contribute to age-related neurodegeneration remains highly debated. Here, we discuss known links between embryonic neurogenesis and neurodegenerative disorders (including common signaling pathways), potential compensatory mechanisms that could delay presentation of neurodegenerative disorders, and the types of model systems that could be used to study these links in vivo.

Human Brain In Vitro Model for Pathogen Infection-Related Neurodegeneration Study

Recent advancements in stem cell biology and tissue engineering have revolutionized the field of neurodegeneration research by enabling the development of sophisticated in vitro human brain models. These models, including 2D monolayer cultures, 3D organoids, organ-on-chips, and bioengineered 3D tissue models, aim to recapitulate the cellular diversity, structural organization, and functional properties of the native human brain. This review highlights how these in vitro brain models have been used to investigate the effects of various pathogens, including viruses, bacteria, fungi, and parasites infection, particularly in the human brain cand their subsequent impacts on neurodegenerative diseases. Traditional studies have demonstrated the susceptibility of different 2D brain cell types to infection, elucidated the mechanisms underlying pathogen-induced neuroinflammation, and identified potential therapeutic targets. Therefore, current methodological improvement brought the technology of 3D models to overcome the challenges of 2D cells, such as the limited cellular diversity, incomplete microenvironment, and lack of morphological structures by highlighting the need for further technological advancements. This review underscored the significance of in vitro human brain cell from 2D monolayer to bioengineered 3D tissue model for elucidating the intricate dynamics for pathogen infection modeling. These in vitro human brain cell enabled researchers to unravel human specific mechanisms underlying various pathogen infections such as SARS-CoV-2 to alter blood-brain-barrier function and Toxoplasma gondii impacting neural cell morphology and its function. Ultimately, these in vitro human brain models hold promise as personalized platforms for development of drug compound, gene therapy, and vaccine. Overall, we discussed the recent progress in in vitro human brain models, their applications in studying pathogen infection-related neurodegeneration, and future directions.

CHIT1 at diagnosis predicts faster disability progression and reflects early microglial activation in multiple sclerosis

Multiple sclerosis (MS) is characterized by heterogeneity in disease course and prediction of long-term outcome remains a major challenge. Here, we investigate five myeloid markers - CHIT1, CHI3L1, sTREM2, GPNMB and CCL18 - in the cerebrospinal fluid (CSF) at diagnostic lumbar puncture in a longitudinal cohort of 192 MS patients. Through mixed-effects and machine learning models, we show that CHIT1 is a robust predictor for faster disability progression. Integrative analysis of 11 CSF and 26 central nervous system (CNS) parenchyma single-cell/nucleus RNA sequencing samples reveals CHIT1 to be predominantly expressed by microglia located in active MS lesions and enriched for lipid metabolism pathways. Furthermore, we find CHIT1 expression to accompany the transition from a homeostatic towards a more activated, MS-associated cell state in microglia. Neuropathological evaluation in post-mortem tissue from 12 MS patients confirms CHIT1 production by lipid-laden phagocytes in actively demyelinating lesions, already in early disease stages. Altogether, we provide a rationale for CHIT1 as an early biomarker for faster disability progression in MS.

Cellular architecture of evolving neuroinflammatory lesions and multiple sclerosis pathology

Multiple sclerosis (MS) is a neurological disease characterized by multifocal lesions and smoldering pathology. Although single-cell analyses provided insights into cytopathology, evolving cellular processes underlying MS remain poorly understood. We investigated the cellular dynamics of MS by modeling temporal and regional rates of disease progression in mouse experimental autoimmune encephalomyelitis (EAE). By performing single-cell spatial expression profiling using in situ sequencing (ISS), we annotated disease neighborhoods and found centrifugal evolution of active lesions. We demonstrated that disease-associated (DA)-glia arise independently of lesions and are dynamically induced and resolved over the disease course. Single-cell spatial mapping of human archival MS spinal cords confirmed the differential distribution of homeostatic and DA-glia, enabled deconvolution of active and inactive lesions into sub-compartments, and identified new lesion areas. By establishing a spatial resource of mouse and human MS neuropathology at a single-cell resolution, our study unveils the intricate cellular dynamics underlying MS.

Single-cell transcriptomics analysis of cellular heterogeneity and immune mechanisms in neurodegenerative diseases

Single-cell transcriptomics analysis is an advanced technology that can describe the intracellular transcriptome in complex tissues. It profiles and analyses datasets by single-cell RNA sequencing. Neurodegenerative diseases are identified by the abnormal apoptosis of neurons in the brain with few or no effective therapy strategies at present, which has been a growing healthcare concern and brought a great burden to society. The transcriptome of individual cells provides deep insights into previously unforeseen cellular heterogeneity and gene expression differences in neurodegenerative disorders. It detects multiple cell subsets and functional changes during pathological progression, which deepens the understanding of the molecular underpinnings and cellular basis of neurodegenerative diseases. Furthermore, the transcriptome analysis of immune cells shows the regulation of immune response. Different subtypes of immune cells and their interaction are found to contribute to disease progression. This finding enables the discovery of novel targets and biomarkers for early diagnosis. In this review, we emphasize the principles of the technology, and its recent progress in the study of cellular heterogeneity and immune mechanisms in neurodegenerative diseases. The application of single-cell transcriptomics analysis in neurodegenerative disorders would help explore the pathogenesis of these diseases and develop novel therapeutic methods.

Mesenchymal stromal cells suppress microglial activation and tumor necrosis factor production

BACKGROUND AIMS

White matter diseases are commonly associated with microglial activation and neuroinflammation. Mesenchymal stromal cells (MSCs) have immunomodulatory properties and thus have the potential to be developed as cell therapy for white matter disease. MSCs interact with resident macrophages to alter the trajectory of inflammation; however, the impact MSCs have on central nervous system macrophages and the effect this has on the progression of white matter disease are unclear.

METHODS

In this study, we utilized numerous assays of varying complexity to model different aspects of white matter disease. These assays ranged from an in vivo spinal cord acute demyelination model to a simple microglial cell line activation assay. Our goal was to investigate the influence of human umbilical cord tissue MSCs on the activation of microglia.

RESULTS

MSCs reduced the production of tumor necrosis factor (TNF) by microglia and decreased demyelinated lesions in the spinal cord after acute focal injury. To determine if MSCs could directly suppress the activation of microglia and to develop an efficient potency assay, we utilized isolated primary microglia from mouse brains and the Immortalized MicroGlial Cell Line (IMG). MSCs suppressed the activation of microglia and the release of TNF after stimulation with lipopolysaccharide, a toll-like receptor agonist.

CONCLUSIONS

In this study, we demonstrated that MSCs altered the immune response after acute injury in the spinal cord. In numerous assays, MSCs suppressed activation of microglia and release of the pro-inflammatory cytokine TNF. Of these assays, IMG could be standardized and used as an effective potency assay to determine the efficacy of MSCs for treating white matter disease or other neuroinflammatory conditions associated with microglial activation.

Bruton's Tyrosine Kinase Inhibitors for Multiple Sclerosis Treatment: A New Frontier

Multiple sclerosis (MS) can cause significant disability to patients via relapse-associated worsening and progression independent of relapses. The causes of neuronal and myelin damage can include lymphocyte-mediated inflammation and microglial activation. Bruton's tyrosine kinase (BTK) is an enzyme that mediates B cell activation and the proinflammatory phenotype of microglia. Inhibiting BTK provides a novel therapeutic target for MS but also has a complicated pharmacology based on binding specificity, CNS penetration, half-life, and enzyme inhibition characteristics. Multiple agents are being studied in phase 3 trials, and each agent will have unique efficacy and safety profiles that must be considered individually.

The role of miRNAs in multiple sclerosis pathogenesis, diagnosis, and therapeutic resistance

In recent years, microRNAs (miRNAs) have gained increased attention from researchers around the globe. Although it is twenty nucleotides long, it can modulate several gene targets simultaneously. Their mal expression is a signature of various pathologies, and they provide the foundation to elucidate the molecular mechanisms of each pathology. Among the debilitating central nervous system (CNS) disorders with a growing prevalence globally is the multiple sclerosis (MS). Moreover, the diagnosis of MS is challenging due to the lack of disease-specific biomarkers, and the diagnosis mainly depends on ruling out other disabilities. MS could adversely affect patients' lives through its progression, and only symptomatic treatments are available as therapeutic options, but an exact cure is yet unavailable. Consequently, this review hopes to further the study of the biological features of miRNAs in MS and explore their potential as a therapeutic target.

The role of biogenic amines in the modulation of monocytes in autoimmune neuroinflammation

Multiple sclerosis (MS) is inflammatory demyelinating and neurodegenerative disease of the central nervous system (CNS) with autoimmune mechanism of development. The study of the neuroimmune interactions is one of the most developing directions in the research of the pathogenesis of MS. The influence of biogenic amines on the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and MS was shown by the modulation of subsets of T-helper cells and B-cells, which plays a crucial role in the autoimmunity of the CNS. However, along with T- and B-cells the critical involvement of mononuclear phagocytes such as dendritic cells, macrophages, and monocytes in the development of neuroinflammation also was shown. It was demonstrated that the activation of microglial cells (resident macrophages of the CNS) could initiate the neuroinflammation in the EAE, suggesting their role at an early stage of the disease. In contrast, monocytes, which migrate from the periphery into the CNS through the blood-brain barrier, mediate the effector phase of the disease and cause neurological disability in EAE. In addition, the clinical efficacy of the therapy with depletion of the monocytes in EAE was shown, suggesting their crucial role in the autoimmunity of the CNS. Biogenic amines, such as epinephrine, norepinephrine, dopamine, and serotonin are direct mediators of the neuroimmune interaction and may affect the pathogenesis of EAE and MS by modulating the immune cell activity and cytokine production. The anti-inflammatory effect of targeting the biogenic amines receptors on the pathogenesis of EAE and MS by suppression of Th17- and Th1-cells, which are critical for the CNS autoimmunity, was shown. However, the latest data showed the potential ability of biogenic amines to affect the functions of the mononuclear phagocytes and their involvement in the modulation of neuroinflammation. This article reviews the literature data on the role of monocytes in the pathogenesis of EAE and MS. The data on the effect of targeting of biogenic amine receptors on the function of monocytes are presented.

Mechanisms underlying the beneficial effects of physical exercise on multiple sclerosis: focus on immune cells

Multiple sclerosis (MS) is a prevalent neuroimmunological illness that leads to neurological disability in young adults. Although the etiology of MS is heterogeneous, it is well established that aberrant activity of adaptive and innate immune cells plays a crucial role in its pathogenesis. Several immune cell abnormalities have been described in MS and its animal models, including T lymphocytes, B lymphocytes, dendritic cells, neutrophils, microglia/macrophages, and astrocytes, among others. Physical exercise offers a valuable alternative or adjunctive disease-modifying therapy for MS. A growing body of evidence indicates that exercise may reduce the autoimmune responses triggered by immune cells in MS. This is partially accomplished by restricting the infiltration of peripheral immune cells into the central nervous system (CNS) parenchyma, curbing hyperactivation of immune cells, and facilitating a transition in the balance of immune cells from a pro-inflammatory to an anti-inflammatory state. This review provides a succinct overview of the correlation between physical exercise, immune cells, and MS pathology, and highlights the potential benefits of exercise as a strategy for the prevention and treatment of MS.

Unraveling the Immunopathogenesis of Multiple Sclerosis: The Dynamic Dance of Plasmablasts and Pathogenic T Cells

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system, characterized by multiple lesions occurring temporally and spatially. Additionally, MS is a disease that predominates in the white population. In recent years, there has been a rapid increase in the number of patients, and it often occurs in young people, with an average age of onset of around 30 years old, but it can also occur in children and the elderly. It is more common in women than men, with a male-to-female ratio of approximately 1:3. As the immunopathogenesis of MS, a group of B cells called plasmablasts controls encephalomyelitis via IL-10 production. These IL-10-producing B cells, called regulatory B cells, suppress inflammatory responses in experimental mouse models of autoimmune diseases including MS. Since it has been clarified that these regulatory B cells are plasmablasts, it is expected that the artificial control of plasmablast differentiation will lead to the development of new treatments for MS. Among CD8-positive T cells in the peripheral blood, the proportion of PD-1-positive cells is decreased in MS patients compared with healthy controls. The dysfunction of inhibitory receptors expressed on T cells is known to be the core of MS immunopathology and may be the cause of chronic persistent inflammation. The PD-1+ CD8+ T cells may also serve as indicators that reflect the condition of each patient in other immunological neurological diseases such as MS. Th17 cells also regulate the development of various autoimmune diseases, including MS. Thus, the restoration of weakened immune regulatory functions may be a true disease-modifying treatment. So far, steroids and immunosuppressants have been the mainstream for autoimmune diseases, but the problem is that this kills not only pathogenic T cells, but also lymphocytes, which are necessary for the body. From this understanding of the immune regulation of MS, we can expect the development of therapeutic strategies that target only pathogenic immune cells.

Mechanosensitive Piezo1 channel in physiology and pathophysiology of the central nervous system

Since the discovery of the mechanosensitive Piezo1 channel in 2010, there has been a significant amount of research conducted to explore its regulatory role in the physiology and pathology of various organ systems. Recently, a growing body of compelling evidence has emerged linking the activity of the mechanosensitive Piezo1 channel to health and disease of the central nervous system. However, the exact mechanisms underlying these associations remain inadequately comprehended. This review systematically summarizes the current research on the mechanosensitive Piezo1 channel and its implications for central nervous system mechanobiology, retrospects the results demonstrating the regulatory role of the mechanosensitive Piezo1 channel on various cell types within the central nervous system, including neural stem cells, neurons, oligodendrocytes, microglia, astrocytes, and brain endothelial cells. Furthermore, the review discusses the current understanding of the involvement of the Piezo1 channel in central nervous system disorders, such as Alzheimer's disease, multiple sclerosis, glaucoma, stroke, and glioma.