Neurodegeneration and demyelination in multiple sclerosis

Neuronal guidance signaling in neurodegenerative diseases: Key regulators that function at neuron-glia and neuroimmune interfaces

The nervous system processes a vast amount of information, performing computations that underlie perception, cognition, and behavior. During development, neuronal guidance genes, which encode extracellular cues, their receptors, and downstream signal transducers, organize neural wiring to generate the complex architecture of the nervous system. It is now evident that many of these neuroguidance cues and their receptors are active during development and are also expressed in the adult nervous system. This suggests that neuronal guidance pathways are critical not only for neural wiring but also for ongoing function and maintenance of the mature nervous system. Supporting this view, these pathways continue to regulate synaptic connectivity, plasticity, and remodeling, and overall brain homeostasis throughout adulthood. Genetic and transcriptomic analyses have further revealed many neuronal guidance genes to be associated with a wide range of neurodegenerative and neuropsychiatric disorders. Although the precise mechanisms by which aberrant neuronal guidance signaling drives the pathogenesis of these diseases remain to be clarified, emerging evidence points to several common themes, including dysfunction in neurons, microglia, astrocytes, and endothelial cells, along with dysregulation of neuron-microglia-astrocyte, neuroimmune, and neurovascular interactions. In this review, we explore recent advances in understanding the molecular and cellular mechanisms by which aberrant neuronal guidance signaling contributes to disease pathogenesis through altered cell-cell interactions. For instance, recent studies have unveiled two distinct semaphorin-plexin signaling pathways that affect microglial activation and neuroinflammation. We discuss the challenges ahead, along with the therapeutic potentials of targeting neuronal guidance pathways for treating neurodegenerative diseases. Particular focus is placed on how neuronal guidance mechanisms control neuron-glia and neuroimmune interactions and modulate microglial function under physiological and pathological conditions. Specifically, we examine the crosstalk between neuronal guidance signaling and TREM2, a master regulator of microglial function, in the context of pathogenic protein aggregates. It is well-established that age is a major risk factor for neurodegeneration. Future research should address how aging and neuronal guidance signaling interact to influence an individual's susceptibility to various late-onset neurological diseases and how the progression of these diseases could be therapeutically blocked by targeting neuronal guidance pathways.

Neuroinflammation: An Oligodendrocentric View

Chronic neuroinflammation, driven by central nervous system (CNS)-resident astrocytes and microglia, as well as infiltration of the peripheral immune system, is an important pathologic mechanism across a range of neurologic diseases. For decades, research focused almost exclusively on how neuroinflammation impacted neuronal function; however, there is accumulating evidence that injury to the oligodendrocyte lineage is an important component for both pathologic and clinical outcomes. While oligodendrocytes are able to undergo an endogenous repair process known as remyelination, this process becomes inefficient and usually fails in the presence of sustained inflammation. The present review focuses on our current knowledge regarding activation of the innate and adaptive immune systems in the chronic demyelinating disease, multiple sclerosis, and provides evidence that sustained neuroinflammation in other neurologic conditions, such as perinatal white matter injury, traumatic brain injury, and viral infections, converges on oligodendrocyte injury. Lastly, the therapeutic potential of targeting the impact of inflammation on the oligodendrocyte lineage in these diseases is discussed.

Astrocytic HSP60 Deletion Induced Astrocyte Senescence and Inhibited Neuroregeneration via Modulating the S1P/Truncated-BDNF Pathway

Heat Shock Protein 60 (HSP60) plays a critical role in maintaining mitochondrial function in astrocytes and has a significant impact on central nervous system (CNS) health. However, how HSP60 regulates the mitochondrial function of astrocytes to inhibit neuroregeneration remains unknown. In this study, we generated astrocyte-specific HSP60 knockout male mice to investigate the consequences of HSP60 deficiency. Firstly, our results confirmed that HSP60 deficiency caused abnormal expression of mitochondrial function-related genes, causing significant mitochondrial dysfunction, which triggered cellular senescence in astrocytes. Moreover, the alterations of 5-hydroxytryptamine 2A receptor (5-HT2AR), glucocorticoid receptor (GR), dopamine D2 receptor (D2R), and N-methyl-D-aspartate receptor subunit 2A (NR2A) expression suggested a disruption in neurotransmission and synaptic plasticity. Additionally, the increased levels of site-1 protease (S1P), truncated brain-derived neurotrophic factor (truncated-BDNF), and synaptophysin indicate synaptic structural and functional impairments. Expectedly, our findings demonstrated mitochondrial dysfunction and cellular senescence in astrocytes, leading to altered expression of neurotransmitter receptors in the cortex, as well as reduced neuronal numbers and neurotransmitter levels in the hippocampus after the deletion of HSP60 in astrocytes of the male mice. Notably, Urolithin A (UA) and the S1P inhibitor, PF429242, were found to alleviate astrocyte senescence and promote neuronal regeneration by inhibiting truncated BDNF expression. In conclusion, our study revealed that HSP60 deficiency in astrocytes induces mitochondrial dysfunction and cellular senescence via the S1P/truncated-BDNF pathway, resulting in disrupted neurotransmitter receptor expression, synaptic protein alterations, and impaired neuroregeneration. These insights underscored the importance of HSP60 in CNS health and provided promising avenues for developing treatments for neurodegenerative disorders.

Novel Emopamil-Binding Protein Inhibitors for Treating Multiple Sclerosis

Provided herein are novel Emopamil-Binding Protein (EBP) inhibitors, pharmaceutical compositions, use of such compounds in treating multiple sclerosis, and processes for preparing such compounds.

Biomedical Applications of Gadolinium-Containing Biomaterials: Not Only MRI Contrast Agent

The potential applications of rare earth elements (REEs) in biomedical fields have been intensively investigated. Numerous studies have shown that doping biomaterials with REEs can enhance their properties. Gadolinium (Gd) is a biocompatible REE that holds promise in biomedical applications. This review examines the use of Gd-doped biomaterials in osteogenic, antimicrobial, anticancer applications, and in bioimaging and bioprobes, as reported in the literature until December 2024. The included studies demonstrate that Gd-containing biomaterials promote osteogenesis, enhance antimicrobial properties, and perform well in anticancer applications and bioimaging. Taken together, they point to the considerable potential of Gd-doped biomaterials and thus to avenues for future research.

Comparative analysis of neuroinflammatory pathways in Alzheimer's disease, Parkinson's disease, and multiple sclerosis: insights into similarities and distinctions

Neurodegenerative diseases, contributing to the significant socioeconomic burden due to aging society, are gaining increasing interest. Despite each disease having different etiologies, neuroinflammation is believed to play a crucial role in Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). In addition to the pathogenic function of inflammation in the brain there is growing evidence that immune responses are essential for neuroregeneration. This review compares and contrasts the neuroinflammatory pathways that selected neurodegenerative diseases share and have in common. In AD, tau tangles and beta-amyloid plaques cause microglia and astrocytes to become activated in an inflammatory response. Alpha-synuclein aggregation stimulate neuroinflammation in Parkinson's disease, especially in the substantia nigra. In Multiple Sclerosis an autoimmune attack on myelin is connected to inflammation via invading immune cells. Commonalities include the release of pro-inflammatory mediators like cytokines and activation of signaling pathways such as NF-κB and MAPK. Comprehending these common routes is essential for discovering early diagnostic possibilities for the diseases and possible tailored treatments. Our work underscores the potential for insights into disease mechanisms. Identifying common targets offers promise for advancing our understanding and potential future treatment approaches across these debilitating disorders.

Ferroptosis and Iron Homeostasis: Molecular Mechanisms and Neurodegenerative Disease Implications

Iron dysregulation has emerged as a pivotal factor in neurodegenerative pathologies, especially through its capacity to promote ferroptosis, a unique form of regulated cell death driven by iron-catalyzed lipid peroxidation. This review synthesizes current evidence on the molecular underpinnings of ferroptosis, focusing on how disruptions in iron homeostasis interact with key antioxidant defenses, such as the system Xc--glutathione-GPX4 axis, to tip neurons toward lethal oxidative damage. Building on these mechanistic foundations, we explore how ferroptosis intersects with hallmark pathologies in Alzheimer's disease (AD) and Parkinson's disease (PD) and examine how iron accumulation in vulnerable brain regions may fuel disease-specific protein aggregation and neurodegeneration. We further surveyed the distinct components of ferroptosis, highlighting the role of lipid peroxidation enzymes, mitochondrial dysfunction, and recently discovered parallel pathways that either exacerbate or mitigate neuronal death. Finally, we discuss how these insights open new avenues for neuroprotective strategies, including iron chelation and lipid peroxidation inhibitors. By highlighting open questions, this review seeks to clarify the current state of knowledge and proposes directions to harness ferroptosis modulation for disease intervention.

Transcriptomic profiling identifies ferroptosis and NF-κB signaling involved in α-dimorphecolic acid regulation of microglial inflammation

BACKGROUND

Microglia-evoked neuroinflammation contributes to neurodegenerative diseases such as multiple sclerosis (MS). Metabolic reprogramming, including changes in polyunsaturated fatty acids (PUFAs), plays a critical role in MS pathophysiology. Previous studies identified reduced plasma α-dimorphecolic acid (α-DIPA), a linoleic acid derivative, in MS patients. This study investigated the anti-inflammatory effects of α-DIPA on microglia and the underlying pathways.

METHODS

Lipopolysaccharide (LPS)-induced BV-2 microglial inflammation was used as an in vitro model. α-DIPA effects were assessed via ELISA for nitric oxide (NO) release, flow cytometry was used to examine cell proliferation, activation and polarization, and transcriptomic analysis was applied to identify key signaling pathways regulated by α-DIPA.

RESULTS

ELISA results showed that exogenous α-DIPA treatment significantly inhibited LPS-induced NO release from BV-2 cells in a concentration-dependent manner. Moreover, flow cytometry analysis suggested that 40 µM α-DIPA treatment significantly repressed LPS-induced BV-2 cell proliferation, activation, as well as M1 and M2 type polarization. Furthermore, transcriptome analysis revealed that exogenous α-DIPA extensively and drastically decreased the transcriptional level of numerous genes that are involved in the regulation of inflammatory responses, for instance, proinflammatory genes such as Tnf and Ccl3 related to IL-17 and TNF-α signaling. In addition, we also observed that the expression of multiple genes in NF-κB signaling were also inhibited greatly by α-DIPA, such as Nfkb2 and Nfkbia. Notably, α-DIPA robustly suppressed LPS-induced mRNA expression of abundant genes participating in the ferroptosis pathway, including Acsl4, Slc7a11, Me1, and Hmox1. Interestingly, the expressions of multiple ferroptosis-related genes were regulated specifically by α-DIPA but not LPS, such as Acsl5, Acsl6, Alox5, Cars, Dpp3, Dpp10, Slc2a5, and Slc7a1.

CONCLUSION

α-DIPA inhibits microglial inflammation likely through regulating the pathways of the ferroptosis and NF-κB signaling. These results provided preliminary evidence for α-DIPA as a potential therapeutic candidate for neurodegenerative diseases like MS.

Technical Assessment of Motor and Behavioral Tests in Rodent Models of Multiple Sclerosis

BACKGROUND

Multiple sclerosis (MS) is a neurodegenerative disorder characterized by progressive motor and cognitive impairments, affecting millions worldwide. It significantly reduces patients' quality of life and imposes a burden on health systems. Despite advances in understanding MS, there is no cure, highlighting the need for effective therapeutic strategies. Preclinical animal models are critical for gaining insights into MS pathophysiology and treatments. However, these models fail to fully replicate the complexity of human MS, making it essential to choose appropriate models and behavioral tests to evaluate their efficacy.

PURPOSE

This review examines various motor and cognitive behavioral tests used in preclinical MS models, discussing their strengths and limitations. The goal is to guide researchers in selecting the most appropriate tests for their models, while providing insights into how these tests are performed and analyzed.

METHODS

We reviewed motor and cognitive behavioral tests used in MS models, detailing test procedures and evaluating their advantages and disadvantages.

RESULTS

This review offers a comprehensive overview that aids researchers in choosing the most suitable tests for their studies, improving the accuracy and reliability of preclinical MS research.

CONCLUSIONS

Understanding the strengths and limitations of these tests is crucial for making informed decisions, leading to better experimental designs and, ultimately, more effective therapeutic interventions for MS.

NLRX1 limits inflammatory neurodegeneration in the anterior visual pathway

Chronic innate immune activation in the central nervous system (CNS) significantly contributes to neurodegeneration in progressive multiple sclerosis (MS). Using multiple experimental autoimmune encephalomyelitis (EAE) models, we discovered that NLRX1 protects neurons in the anterior visual pathway from inflammatory neurodegeneration. We quantified retinal ganglion cell (RGC) density and optic nerve axonal degeneration, gliosis, and T-cell infiltration in Nlrx1-/- and wild-type (WT) EAE mice and found increased RGC loss and axonal injury in Nlrx1-/- mice compared to WT mice in both active immunization EAE and spontaneous opticospinal encephalomyelitis (OSE) models. To minimize the effects of Nlrx1-/- on peripheral lymphocyte priming during EAE, we performed adoptive transfer experiments, in which activated myelin-specific T cells were transferred into lymphocyte-deficient Rag-/- or Nlrx1-/-Rag-/- mice. In this model, we found more severe microgliosis and astrogliosis in the optic nerve of Nlrx1-/-Rag-/- mice compared to Rag-/- mice, suggesting a regulatory role of NLRX1 in innate immune cells. Transcriptome analysis in primary astrocytes activated with LPS and IFNγ demonstrated that NLRX1 suppresses NF-κB activation and regulates mitochondrial oxidative phosphorylation in inflammatory reactive astrocytes. The novel pharmacologic NLRX1 activators NX-13 and LABP-66 decreased LPS-mediated gene expression of inflammatory cytokines and chemokines in mixed glial cultures. Moreover, treating EAE mice with oral LABP-66, compared to vehicle, after the onset of paralysis resulted in less anterior visual pathway neurodegeneration. These data suggest that pharmacologic NLRX1 activators have the potential to limit inflammatory neurodegeneration. This study highlights that NLRX1 could serve as a promising target for neuroprotection in progressive MS and other neurodegenerative diseases. Further studies are needed to better understand the cell-specific mechanisms underlying the neuroprotective role of NLRX1 in response to inflammation in the CNS.

Thalamic volume differentiates multiple sclerosis from neuromyelitis optica spectrum disorder: MRI-based retrospective study

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are distinct demyelinating diseases of the central nervous system, each characterized by unique patterns of motor, sensory, and visual dysfunction. While MS typically affects the brain and spinal cord, NMOSD predominantly targets the optic nerves and spinal cord. This study aims to elucidate the morphometric differences between MS and NMOSD by focusing on gray matter volume changes in specific brain regions. We also examined if temporal changes in follow-up MRI differentiate the two disorders. We analyzed anatomical T1-weighted MRI scans from 24 patients with NMOSD and 25 patients with MS using the CAT12 toolbox. Our analysis revealed significant differences in gray matter structure between the two patient groups. Notably, the thalamus was found to be consistently smaller in patients with MS compared to those with NMOSD. This finding aligns with previous research highlighting thalamic atrophy as a hallmark of MS and further underscores the thalamus's role in the disease's pathology. These results provide valuable insights into the distinct neuroanatomical features of MS and NMOSD, contributing to a better understanding of the mechanisms underlying these diseases. The study also emphasizes the importance of advanced imaging techniques in differentiating between MS and NMOSD, which may have implications for diagnosis and treatment strategies.

Inflammatory and Nutritional Markers as Indicators for Diagnosing and Assessing Disease Activity in MS and NMOSD

Background

Inflammation and nutritional markers have recently gained recognition for their roles in the fabrication of cognitive control centers demyelinating illnesses. Inflammatory indices such as the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammatory index (SII), and systemic inflammatory response index (SIRI), along with nutritional markers like albumin (ALB), hemoglobin (HB), and body mass index (BMI), may predict disease occurrence. However, their potential in evaluating diseases such as multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) remains unexplored.

Methods

We retrospectively evaluated 249 NMOSD patients, 244 MS patients, and 249 healthy controls (HC), calculating MLR, NLR, PLR, SII, and SIRI, and measuring ALB, HB, and BMI levels. Logistic regression and ROC curves were used to develop and validate models for diagnosing and differentiating MS and NMOSD. Further, 35 MS patients, 38 NMOSD patients, and 85 matched HC were recruited for validation, and marker changes were monitored over six months.

Results

Comparing MS and NMOSD groups with HC, MLR, NLR, SII, and SIRI were significantly greater, while ALB levels were lower (P<0.05). NMOSD patients exhibited higher MLR, NLR, SII, and SIRI, and lower HB and ALB levels contrasted with MS patients (P<0.05). These markers correlated negatively with total T lymphocytes and positively with C-reactive protein, the Expanded Disability Status Scale (EDSS), and MRI T2 lesion count. Following remission, NLR, SII, and SIRI decreased, while ALB increased over six months (P<0.05). Diagnostic models based on these markers showed AUCs of 0.840 (95% CI:0.806-0.875) for MS and 0.905 (95% CI:0.877-0.933) for NMOSD. Differential diagnosis between MS and NMOSD showed an AUC of 0.806 (95% CI: 0.750-0.863).

Conclusion

Inflammatory and nutritional markers are promising for assessing disease activity in MS and NMOSD. Diagnostic models based on these markers enhance the accuracy and clinical value of differentiating between the two conditions.

The Mechanistic Link Between Tau-Driven Proteotoxic Stress and Cellular Senescence in Alzheimer's Disease

In Alzheimer's disease (AD), tau dissociates from microtubules (MTs) due to hyperphosphorylation and misfolding. It is degraded by various mechanisms, including the 20S proteasome, chaperone-mediated autophagy (CMA), 26S proteasome, macroautophagy, and aggrephagy. Neurofibrillary tangles (NFTs) form upon the impairment of aggrephagy, and eventually, the ubiquitin chaperone valosin-containing protein (VCP) and heat shock 70 kDa protein (HSP70) are recruited to the sites of NFTs for the extraction of tau for the ubiquitin-proteasome system (UPS)-mediated degradation. However, the impairment of tau degradation in neurons allows tau to be secreted into the extracellular space. Secreted tau can be monomers, oligomers, and paired helical filaments (PHFs), which are seeding competent pathological tau that can be endocytosed/phagocytosed by healthy neurons, microglia, astrocytes, oligodendrocyte progenitor cells (OPCs), and oligodendrocytes, often causing proteotoxic stress and eventually triggers senescence. Senescent cells secrete various senescence-associated secretory phenotype (SASP) factors, which trigger cellular atrophy, causing decreased brain volume in human AD. However, the molecular mechanisms of proteotoxic stress and cellular senescence are not entirely understood and are an emerging area of research. Therefore, this comprehensive review summarizes pertinent studies that provided evidence for the sequential tau degradation, failure, and the mechanistic link between tau-driven proteotoxic stress and cellular senescence in AD.

Exploring the underlying mechanisms of exercise as therapy for multiple sclerosis: insights from preclinical studies

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system CNS characterized by demyelination, inflammation, and neurodegenerative changes, making it the most common nontraumatic disabling neurological disease in young adults. While current pharmacological treatments primarily target immunomodulation or immunosuppression, exercise is gaining increasing attention from the scientific community as an adjunctive therapy. This review explores the potential biological mechanisms of exercise in animal models of MS, focusing on its effects on neuroprotection and inflammation. The review examines how exercise inhibits pro-inflammatory microglial reactivity, stabilizes the blood-brain barrier, and enhances neurotrophic factor expression in animal studies. Future research directions are proposed by summarizing the evidence and limitations of existing animal models of MS, emphasizing the need to further validate these mechanisms in humans to better integrate exercise into the comprehensive management of MS. Additionally, investigating exercise-induced biomarkers for MS symptom reduction may provide a scientific basis for new therapeutic strategies.

Endothelial Cell-Derived Soluble CD200 Determines the Ability of Immune Cells to Cross the Blood-Brain Barrier

The infiltration of immune cells into the central nervous system mediates the development of autoimmune neuroinflammatory diseases. We previously showed that the loss of either Fabp5 or calnexin causes resistance to the induction of experimental autoimmune encephalomyelitis (EAE) in mice, an animal model of multiple sclerosis (MS). Here we show that brain endothelial cells lacking either Fabp5 or calnexin have an increased abundance of cell surface CD200 and soluble CD200 (sCD200) as well as decreased T-cell adhesion. In a tissue culture model of the blood-brain barrier, antagonizing the interaction of CD200 and sCD200 with T-cell CD200 receptor (CD200R1) via anti-CD200 blocking antibodies or the RNAi-mediated inhibition of CD200 production by endothelial cells increased T-cell adhesion and transmigration across monolayers of endothelial cells. Our findings demonstrate that sCD200 produced by brain endothelial cells regulates immune cell trafficking through the blood-brain barrier and is primarily responsible for preventing activated T-cells from entering the brain.

STING: Stay near to STIM(1) neuroprotection

In a recent publication in Cell, Woo et al.1 report that stimulator of interferon genes (STING) links inflammation with glutamate-driven excitotoxicity to induce ferroptosis, identifying a mechanism of inflammation-induced neurodegeneration and also a novel candidate therapeutic target for multiple sclerosis.