Ferroptosis Mediates Cuprizone-Induced Loss of Oligodendrocytes and Demyelination

Mechanism of Cu entry into the brain: many unanswered questions

Brain tissue requires high amounts of copper (Cu) for its key physiological processes, such as energy production, neurotransmitter synthesis, maturation of neuropeptides, myelination, synaptic plasticity, and radical scavenging. The requirements for Cu in the brain vary depending on specific brain regions, cell types, organism age, and nutritional status. Cu imbalances cause or contribute to several life-threatening neurologic disorders including Menkes disease, Wilson disease, Alzheimer's disease, Parkinson's disease, and others. Despite the well-established role of Cu homeostasis in brain development and function, the mechanisms that govern Cu delivery to the brain are not well defined. This review summarizes available information on Cu transfer through the brain barriers and discusses issues that require further research.

Advances in research on immunocyte iron metabolism, ferroptosis, and their regulatory roles in autoimmune and autoinflammatory diseases

Autoimmune diseases commonly affect various systems, but their etiology and pathogenesis remain unclear. Currently, increasing research has highlighted the role of ferroptosis in immune regulation, with immune cells being a crucial component of the body's immune system. This review provides an overview and discusses the relationship between ferroptosis, programmed cell death in immune cells, and autoimmune diseases. Additionally, it summarizes the role of various key targets of ferroptosis, such as GPX4 and TFR, in immune cell immune responses. Furthermore, the release of multiple molecules, including damage-associated molecular patterns (DAMPs), following cell death by ferroptosis, is examined, as these molecules further influence the differentiation and function of immune cells, thereby affecting the occurrence and progression of autoimmune diseases. Moreover, immune cells secrete immune factors or their metabolites, which also impact the occurrence of ferroptosis in target organs and tissues involved in autoimmune diseases. Iron chelators, chloroquine and its derivatives, antioxidants, chloroquine derivatives, and calreticulin have been demonstrated to be effective in animal studies for certain autoimmune diseases, exerting anti-inflammatory and immunomodulatory effects. Finally, a brief summary and future perspectives on the research of autoimmune diseases are provided, aiming to guide disease treatment strategies.

Targeting ferroptosis in neuroimmune and neurodegenerative disorders for the development of novel therapeutics

Neuroimmune and neurodegenerative ailments impose a substantial societal burden. Neuroimmune disorders involve the intricate regulatory interactions between the immune system and the central nervous system. Prominent examples of neuroimmune disorders encompass multiple sclerosis and neuromyelitis optica. Neurodegenerative diseases result from neuronal degeneration or demyelination in the brain or spinal cord, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. The precise underlying pathogenesis of these conditions remains incompletely understood. Ferroptosis, a programmed form of cell death characterised by lipid peroxidation and iron overload, plays a pivotal role in neuroimmune and neurodegenerative diseases. In this review, we provide a detailed overview of ferroptosis, its mechanisms, pathways, and regulation during the progression of neuroimmune and neurodegenerative diseases. Furthermore, we summarise the impact of ferroptosis on neuroimmune-related cells (T cells, B cells, neutrophils, and macrophages) and neural cells (glial cells and neurons). Finally, we explore the potential therapeutic implications of ferroptosis inhibitors in diverse neuroimmune and neurodegenerative diseases.

The physiological and pathophysiological roles of copper in the nervous system

Copper is a critical trace element in biological systems due the vast number of essential enzymes that require the metal as a cofactor, including cytochrome c oxidase, superoxide dismutase and dopamine-β-hydroxylase. Due its key role in oxidative metabolism, antioxidant defence and neurotransmitter synthesis, copper is particularly important for neuronal development and proper neuronal function. Moreover, increasing evidence suggests that copper also serves important functions in synaptic and network activity, the regulation of circadian rhythms, and arousal. However, it is important to note that because of copper's ability to redox cycle and generate reactive species, cellular levels of the metal must be tightly regulated to meet cellular needs while avoiding copper-induced oxidative stress. Therefore, it is essential that the intricate system of copper transporters, exporters, copper chaperones and copper trafficking proteins function properly and in coordinate fashion. Indeed, disorders of copper metabolism such as Menkes disease and Wilson disease, as well as diseases linked to dysfunction of copper-requiring enzymes, such as SOD1-linked amyotrophic lateral sclerosis, demonstrate the dramatic neurological consequences of altered copper homeostasis. In this review, we explore the physiological importance of copper in the nervous system as well as pathologies related to improper copper handling.

The neuropathobiology of multiple sclerosis

Chronic low-grade inflammation and neuronal deregulation are two components of a smoldering disease activity that drives the progression of disability in people with multiple sclerosis (MS). Although several therapies exist to dampen the acute inflammation that drives MS relapses, therapeutic options to halt chronic disability progression are a major unmet clinical need. The development of such therapies is hindered by our limited understanding of the neuron-intrinsic determinants of resilience or vulnerability to inflammation. In this Review, we provide a neuron-centric overview of recent advances in deciphering neuronal response patterns that drive the pathology of MS. We describe the inflammatory CNS environment that initiates neurotoxicity by imposing ion imbalance, excitotoxicity and oxidative stress, and by direct neuro-immune interactions, which collectively lead to mitochondrial dysfunction and epigenetic dysregulation. The neuronal demise is further amplified by breakdown of neuronal transport, accumulation of cytosolic proteins and activation of cell death pathways. Continuous neuronal damage perpetuates CNS inflammation by activating surrounding glia cells and by directly exerting toxicity on neighbouring neurons. Further, we explore strategies to overcome neuronal deregulation in MS and compile a selection of neuronal actuators shown to impact neurodegeneration in preclinical studies. We conclude by discussing the therapeutic potential of targeting such neuronal actuators in MS, including some that have already been tested in interventional clinical trials.

The iron maiden: Oligodendroglial metabolic dysfunction in multiple sclerosis and mitochondrial signaling

Multiple sclerosis (MS) is an autoimmune disease, governed by oligodendrocyte (OL) dystrophy and central nervous system (CNS) demyelination manifesting variable neurological impairments. Mitochondrial mechanisms may drive myelin biogenesis maintaining the axo-glial unit according to dynamic requisite demands imposed by the axons they ensheath. The promotion of OL maturation and myelination by actively transporting thyroid hormone (TH) into the CNS and thereby facilitating key transcriptional and metabolic pathways that regulate myelin biogenesis is fundamental to sustain the profound energy demands at each axo-glial interface. Deficits in regulatory functions exerted through TH for these physiological roles to be orchestrated by mature OLs, can occur in genetic and acquired myelin disorders, whereby mitochondrial efficiency and eventual dysfunction can lead to profound oligodendrocytopathy, demyelination and neurodegenerative sequelae. TH-dependent transcriptional and metabolic pathways can be dysregulated during acute and chronic MS lesion activity depriving OLs from critical acetyl-CoA biochemical mechanisms governing myelin lipid biosynthesis and at the same time altering the generation of iron metabolism that may drive ferroptotic mechanisms, leading to advancing neurodegeneration.

Rapid and prolonged response of oligodendrocyte lineage cells in standard acute cuprizone demyelination model revealed by in situ hybridization

Dietary administration of a copper chelator, cuprizone (CPZ), has long been reported to induce intense and reproducible demyelination of several brain structures such as the corpus callosum. Despite the widespread use of CPZ as an animal model for demyelinating diseases such as multiple sclerosis (MS), the mechanism by which it induces demyelination and then allows robust remyelination is still unclear. An intensive mapping of the cell dynamics of oligodendrocyte (OL) lineage during the de- and remyelination course would be particularly important for a deeper understanding of this model. Here, using a panel of OL lineage cell markers as in situ hybridization (ISH) probes, including Pdgfra, Plp, Mbp, Mog, Enpp6, combined with immunofluorescence staining of CC1, SOX10, we provide a detailed dynamic profile of OL lineage cells during the entire course of the model from 1, 2, 3.5 days, 1, 2, 3, 4,5 weeks of CPZ treatment, as well as after 1, 2, 3, 4 weeks of recovery from CPZ treatment. The result showed an unexpected early death of mature OLs and response of OL progenitor cells (OPCs) in vivo upon CPZ challenge, and a prolonged upregulation of myelin-forming OLs compared to the intact control even 4 weeks after CPZ withdrawal. These data may serve as a basic reference system for future studies of the effects of any intervention on de- and remyelination using the CPZ model, and imply the need to optimize the timing windows for the introduction of pro-remyelination therapies in demyelinating diseases such as MS.

Ferroptosis in health and disease

Ferroptosis is a pervasive non-apoptotic form of cell death highly relevant in various degenerative diseases and malignancies. The hallmark of ferroptosis is uncontrolled and overwhelming peroxidation of polyunsaturated fatty acids contained in membrane phospholipids, which eventually leads to rupture of the plasma membrane. Ferroptosis is unique in that it is essentially a spontaneous, uncatalyzed chemical process based on perturbed iron and redox homeostasis contributing to the cell death process, but that it is nonetheless modulated by many metabolic nodes that impinge on the cells' susceptibility to ferroptosis. Among the various nodes affecting ferroptosis sensitivity, several have emerged as promising candidates for pharmacological intervention, rendering ferroptosis-related proteins attractive targets for the treatment of numerous currently incurable diseases. Herein, the current members of a Germany-wide research consortium focusing on ferroptosis research, as well as key external experts in ferroptosis who have made seminal contributions to this rapidly growing and exciting field of research, have gathered to provide a comprehensive, state-of-the-art review on ferroptosis. Specific topics include: basic mechanisms, in vivo relevance, specialized methodologies, chemical and pharmacological tools, and the potential contribution of ferroptosis to disease etiopathology and progression. We hope that this article will not only provide established scientists and newcomers to the field with an overview of the multiple facets of ferroptosis, but also encourage additional efforts to characterize further molecular pathways modulating ferroptosis, with the ultimate goal to develop novel pharmacotherapies to tackle the various diseases associated with - or caused by - ferroptosis.

Selenoprotein I is indispensable for ether lipid homeostasis and proper myelination

Selenoprotein I (SELENOI) catalyzes the final reaction of the CDP-ethanolamine branch of the Kennedy pathway, generating the phospholipids phosphatidylethanolamine (PE) and plasmenyl-PE. Plasmenyl-PE is a key component of myelin and is characterized by a vinyl ether bond that preferentially reacts with oxidants, thus serves as a sacrificial antioxidant. In humans, multiple loss-of-function mutations in genes affecting plasmenyl-PE metabolism have been implicated in hereditary spastic paraplegia, including SELENOI. Herein, we developed a mouse model of nervous system-restricted SELENOI deficiency that circumvents embryonic lethality caused by constitutive deletion and recapitulates phenotypic features of hereditary spastic paraplegia. Resulting mice exhibited pronounced alterations in brain lipid composition, which coincided with motor deficits and neuropathology including hypomyelination, elevated reactive gliosis, and microcephaly. Further studies revealed increased lipid peroxidation in oligodendrocyte lineage cells and disrupted oligodendrocyte maturation both in vivo and in vitro. Altogether, these findings detail a critical role for SELENOI-derived plasmenyl-PE in myelination that is of paramount importance for neurodevelopment.

Research trends and hotspots of ferroptosis in neurodegenerative diseases from 2013 to 2023: A bibliometrics study

Background

With the aging population, the incidence of neurodegenerative diseases increases yearly, seriously impacting human health. Various journals have published studies on the pathogenesis of ferroptosis in neurodegenerative diseases. However, bibliometric analysis in this field is still lacking. The study aims to visually analyze global research trends in this field over the past decade.

Methods

The articles and reviews regarding ferroptosis in neurodegenerative diseases were retrieved from the Web of Science on September 1, 2023. Citespace [version 6.2. R4 (64-bit)] and VOSviewer (version 1.6.18) were used to conduct the bibliometric and knowledge-map analysis.

Results

In total, 370 studies were included in the paper and ranked by their citation frequency. Many articles on ferroptosis in neurodegenerative diseases have been published in the past decade. The country, institution, author, and journal with the highest publications were China, Guangzhou Medical University, Maher, Pamela, and Free Radical Biology And Medicine, respectively. The analysis of keyword co-occurrence indicated that research frontiers were molecular mechanisms of ferroptosis in neurodegenerative diseases, especially a few key pathways that triggered ferroptosis in these diseases, including lipid peroxidation signaling, iron metabolism, and GSH/GPX4 signaling. In addition, ferroptosis inhibitors such as liproxstatins and ferrostatins had protective effects in animal models of neurodegenerative diseases. Therefore, future attention should also be focused on therapeutic drugs that target ferroptosis.

Conclusion

This study comprehensively analyzed the publications on ferroptosis in neurodegenerative diseases from a bibliometric perspective. Research on this topic is currently expanding at a rapid pace, and the China holds a leading position in this field by its scientific achievements and productivity. Moreover, the research frontiers were molecular mechanisms of ferroptosis in neurodegenerative diseases and developing targeted therapeutic drugs. In summary, our results showed an all-sided overview of the knowledge atlas and a valuable reference for the future research in this field.

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

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

The role of myelin in neurodegeneration: implications for drug targets and neuroprotection strategies

Myelination of axons in the central nervous system offers numerous advantages, including decreased energy expenditure for signal transmission and enhanced signal speed. The myelin sheaths surrounding an axon consist of a multi-layered membrane that is formed by oligodendrocytes, while specific glycoproteins and lipids play various roles in this formation process. As beneficial as myelin can be, its dysregulation and degeneration can prove detrimental. Inflammation, oxidative stress, and changes in cellular metabolism and the extracellular matrix can lead to demyelination of these axons. These factors are hallmark characteristics of certain demyelinating diseases including multiple sclerosis. The effects of demyelination are also implicated in primary degeneration in diseases such as glaucoma and Alzheimer's disease, as well as in processes of secondary degeneration. This reveals a relationship between myelin and secondary processes of neurodegeneration, including resultant degeneration following traumatic injury and transsynaptic degeneration. The role of myelin in primary and secondary degeneration is also of interest in the exploration of strategies and targets for remyelination, including the use of anti-inflammatory molecules or nanoparticles to deliver drugs. Although the use of these methods in animal models of diseases have shown to be effective in promoting remyelination, very few clinical trials in patients have met primary end points. This may be due to shortcomings or considerations that are not met while designing a clinical trial that targets remyelination. Potential solutions include diversifying disease targets and requiring concomitant interventions to promote rehabilitation.

Cuproptosis and copper deficiency in ischemic vascular injury and repair

Ischemic vascular diseases are on the rise globally, including ischemic heart diseases, ischemic cerebrovascular diseases, and ischemic peripheral arterial diseases, posing a significant threat to life. Copper is an essential element in various biological processes, copper deficiency can reduce blood vessel elasticity and increase platelet aggregation, thereby increasing the risk of ischemic vascular disease; however, excess copper ions can lead to cytotoxicity, trigger cell death, and ultimately result in vascular injury through several signaling pathways. Herein, we review the role of cuproptosis and copper deficiency implicated in ischemic injury and repair including myocardial, cerebral, and limb ischemia. We conclude with a perspective on the therapeutic opportunities and future challenges of copper biology in understanding the pathogenesis of ischemic vascular disease states.

Ameliorative effects of acetyl-L-carnitine on corpus callosum and functional recovery in demyelinated mouse model

AIM

Multiple sclerosis (MS) is the most common chronic inflammatory demyelinating disease of the central nervous system. Oxidative stress via distinct pathobiological pathways plays a pivotal role in the formation and persistence of MS lesions. Acetyl-L-carnitine (ALC) facilitates the uptake of acetyl coenzyme-A into the mitochondria by a fatty acid oxidation process. ALC could be a therapeutic antioxidant in the myelin repair process. This study explored the potential neuroprotective effects of ALC in cuprizone (CPZ) intoxicated mice.

MATERIALS AND METHODS

Thirty male C57BL/6 mice were divided into three groups. The control animals received a normal diet. The CPZ and CPZ + ALC groups were fed with a 0.2% cuprizone diet for 12 weeks. In the CPZ + ALC group, animals received ALC (300 mg/kg/day) from the 10th -12th weeks. Animals were evaluated functionally by beam walking test (BWT) weekly. Eventually, the corpus callosum (CC) was extracted for histological, biochemical, and molecular studies.

RESULTS

BWT data showed ALC significantly improves balance and gait in the demyelinating mouse model. Histological staining represented ALC effectively increased remyelination in the CC. Biochemical evaluations demonstrated ALC decreased the malondialdehyde level with a parallel increase in the reduced glutathione and catalase activity levels in the CC. Molecular analysis revealed that ALC significantly increased the expression of oligodendrocyte transcription-2 (Olig-2) and Poly lipoproteins (Plp) genes in the CC.

CONCLUSIONS

ALC improved balance and motor coordination in the demyelinated mouse model. It may be by reducing the levels of free radicals and increasing the expression of Olig-2 and Plp as myelin-related genes.

Interleukin-6 Inhibits Expression of miR-204-5p, a Regulator of Oligodendrocyte Differentiation: Involvement of miR-204-5p in the Prevention of Chemical-Induced Oligodendrocyte Impairment

Oligodendrocytes (OLs) form myelin sheaths around axons in the central nervous system (CNS) facilitate the propagation of action potentials. The studies have shown that the differentiation and maturation of OLs involve microRNA (miR) regulation. The recent findings have addressed that miR-204 regulates OL differentiation in culture. In this study, through in situ hybridization in combination with immunohistochemistry, we showed that microRNA-204-5p in the corpus callosum was mainly expressed in OLs immunoreactive with adenomatous polyposis coli (APC), an OL marker. We also found miR-204-5p expression in mature OLs was suppressed by the addition of interleukin-6 (IL-6). Moreover, IL-6-induced inhibition of miR-204-5p expression was blocked by the addition of the inhibitors specific for p38 mitogen-activated protein kinase (p38MAPK) or phosphatidylinositol 3-kinase (PI3K) pathway. We further utilized a rat model by feeding cuprizone (CPZ)-containing diet for 3 weeks to induce demyelination and gliosis in the corpus callosum, as well as the upregulation of IL-6 gene expression significantly. Despite that miR-204-5p expression in the corpus callosum was not altered after feeding by CPZ for 3 weeks, its expression was increased and IL-6 transcription was decreased in the corpus callosum of the recovery group that was fed by CPZ for the first 2 weeks and by the regular diet for one more week. Our data demonstrate that miR-204-5p expression in OLs declined under the influence of the inflamed microenvironment. The findings that an increase in miR-204-5p and declined IL-6 expression observed in the recovery group might be involved with OL repair in the corpus callosum, and also shed light on a potential role for miR-204-5p in OL homeostasis following the white matter injury.

Iron metabolism disorder and multiple sclerosis: a comprehensive analysis

Background

Multiple sclerosis (MS) is the most common chronic inflammatory disease of the central nervous system. Currently, the pathological mechanisms of MS are not fully understood, but research has suggested that iron metabolism disorder may be associated with the onset and clinical manifestations of MS.

Methods and materials

The study utilized publicly available databases and bioinformatics techniques for gene expression data analysis, including differential expression analysis, weighted correlation network analysis, gene enrichment analysis, and construction of logistic regression models. Subsequently, Mendelian randomization was used to assess the causal relationship between different iron metabolism markers and MS.

Results

This study identified IREB2, LAMP2, ISCU, ATP6V1G1, ATP13A2, and SKP1 as genes associated with multiple sclerosis (MS) and iron metabolism, establishing their multi-gene diagnostic value for MS with an AUC of 0.83. Additionally, Mendelian randomization analysis revealed a potential causal relationship between transferrin saturation and MS (p=2.22E-02; OR 95%CI=0.86 (0.75, 0.98)), as well as serum transferrin and MS (p=2.18E-04; OR 95%CI=1.22 (1.10, 1.36)).

Conclusion

This study comprehensively explored the relationship between iron metabolism and MS through integrated bioinformatics analysis and Mendelian randomization methods. The findings provide important insights for further research into the role of iron metabolism disorder in the pathogenesis of MS and offer crucial theoretical support for the treatment of MS.

Targeted RNAseq Revealed the Gene Expression Signature of Ferroptosis-Related Processes Associated with Disease Severity in Patients with Multiple Sclerosis

Detrimental molecular processes in multiple sclerosis (MS) lead to the cellular accumulation of lipid peroxidation products and iron in the CNS, which represents the main driving force for ferroptosis. Ferroptosis is an iron-dependent form of regulated cell death, with proposed roles in neurodegeneration, oligodendrocyte loss and neuroinflammation in the pathogenesis of MS. Ferroptosis-related gene expression signature and molecular markers, which could reflect MS severity and progression, are currently understudied in humans. To tackle these challenges, we have applied a curated approach to create and experimentally analyze a comprehensive panel of ferroptosis-related genes covering a wide range of biological processes associated with ferroptosis. We performed the first ferroptosis-related targeted RNAseq on PBMCs from highly distinctive MS phenotype groups: mild relapsing-remitting (RR) (n = 24) and severe secondary progressive (SP) (n = 24), along with protein detection of GPX4 and products of lipid peroxidation (MDA and 4-HNE). Out of 138 genes, 26 were differentially expressed genes (DEGs), indicating changes in both pro- and anti-ferroptotic genes, representing a molecular signature associated with MS severity. The top three DEGs, as non-core ferroptosis genes, CDKN1A, MAP1B and EGLN2, were replicated by qPCR to validate findings in independent patient groups (16 RR and 16 SP MS). Co-expression and interactions of DEGs were presented as additional valuable assets for deeper understanding of molecular mechanisms and key targets related to MS severity. Our study integrates a wide genetic signature and biochemical markers related to ferroptosis in easily obtainable PBMCs of MS patients with clinical data and disease severity, thus providing novel molecular markers which can complement disease-related changes in the brain and undergo further research as potential therapeutic targets.

Soluble epoxide hydrolase inhibitor (TPPU) alleviates ferroptosis by regulating CCL5 after intracerebral hemorrhage in mice

Soluble epoxide hydrolase (sEH) inhibition has been shown multiple beneficial effects against brain injuries of Intracerebral hemorrhage (ICH). However, the underlying mechanism of its neuroprotective effects after ICH has not been explained fully. Ferroptosis, a new form of iron-dependent programmed cell death, has been shown to be implicated in the secondary injuries after ICH. In this study, We examined whether sEH inhibition can alleviate brain injuries of ICH through inhibiting ferroptosis. Expression of several markers for ferroptosis was observed in the peri-hematomal brain tissues in mice after ICH. lip-1, a ferroptosis inhibitor, alleviated iron accumulation, lipid peroxidation and the secondary damages post-ICH in mice model. Intraperitoneal injection of 1-Trifluoromethoxyphenyl-3- (1-propionylpiperidin-4-yl)urea (TPPU), a highly selective sEH inhibitor, could inhibit ferroptosis and alleviate brain damages in ICH mice. Furthermore, RNA-sequencing was applied to explore the potential regulatory mechanism underlying the effects of TPPU in ferroptosis after ICH. C-C chemokine ligand 5 (CCL5) may be the key factor by which TPPU regulated ferroptosis after ICH since CCL5 antagonist could mimic the effects of TPPU and CCL5 reversed the inhibitive effect of TPPU on ferroptosis and the neuroprotective effects of TPPU on secondary damage after ICH. Taken together, these data indicate that ferroptosis is a key pathological feature of ICH and Soluble epoxide hydrolase inhibitor can exert neuroprotective effect by preventing ferroptosis after ICH.

Tremendous Fidelity of Vitamin D3 in Age-related Neurological Disorders

Vitamin D3 (VD) is a secosteroid hormone and shows a pleiotropic effect in brain-related disorders where it regulates redox imbalance, inflammation, apoptosis, energy production, and growth factor synthesis. Vitamin D3's active metabolic form, 1,25-dihydroxy Vitamin D3 (1,25(OH)2D3 or calcitriol), is a known regulator of several genes involved in neuroplasticity, neuroprotection, neurotropism, and neuroinflammation. Multiple studies suggest that VD deficiency can be proposed as a risk factor for the development of several age-related neurological disorders. The evidence for low serum levels of 25-hydroxy Vitamin D3 (25(OH)D3 or calcidiol), the major circulating form of VD, is associated with an increased risk of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), dementia, and cognitive impairment. Despite decades of evidence on low VD association with neurological disorders, the precise molecular mechanism behind its beneficial effect remains controversial. Here, we will be delving into the neurobiological importance of VD and discuss its benefits in different neuropsychiatric disorders. The focus will be on AD, PD, and HD as they share some common clinical, pathological, and epidemiological features. The central focus will be on the different attributes of VD in the aspect of its anti-oxidative, anti-inflammatory, anti-apoptotic, anti-cholinesterase activity, and psychotropic effect in different neurodegenerative diseases.

Copper Metabolism and Cuproptosis: Molecular Mechanisms and Therapeutic Perspectives in Neurodegenerative Diseases

Copper is an essential trace element, and plays a vital role in numerous physiological processes within the human body. During normal metabolism, the human body maintains copper homeostasis. Copper deficiency or excess can adversely affect cellular function. Therefore, copper homeostasis is stringently regulated. Recent studies suggest that copper can trigger a specific form of cell death, namely, cuproptosis, which is triggered by excessive levels of intracellular copper. Cuproptosis induces the aggregation of mitochondrial lipoylated proteins, and the loss of iron-sulfur cluster proteins. In neurodegenerative diseases, the pathogenesis and progression of neurological disorders are linked to copper homeostasis. This review summarizes the advances in copper homeostasis and cuproptosis in the nervous system and neurodegenerative diseases. This offers research perspectives that provide new insights into the targeted treatment of neurodegenerative diseases based on cuproptosis.

Targeting Ferroptosis Promotes Functional Recovery by Mitigating White Matter Injury Following Acute Carbon Monoxide Poisoning

Survivors experiencing acute carbon monoxide poisoning (ACMP) tend to develop white matter injury (WMI). The mechanism of ACMP-induced WMI remains unclear. Considering the role of ferroptosis in initiating oligodendrocyte damage to deteriorate WMI, exploring therapeutic options to attenuate ferroptosis is a feasible approach to alleviating WMI. Our results indicated that ACMP induced accumulation of iron and reactive oxygen species (ROS) eventually leading to WMI and motor impairment after ACMP. Furthermore, ferrostatin-1 reduced iron and ROS deposition to alleviate ferroptosis, thereafter reducing WMI to promote the recovery of motor function. The nuclear factor erythroid-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway was found to be involved in alleviating ferroptosis as seen with the administration of ferrostatin-1. The present study rationalizes that targeting ferroptosis to alleviate WMI is a feasible therapeutic strategy for managing ACMP.

The role of ferroptosis in central nervous system damage diseases

Ferroptosis is a form of cell death, i.e., programmed cell death characterized by lipid peroxidation and iron dependence, which has unique morphological and biochemical properties. This unique mode of cell death is driven by iron-dependent phospholipid peroxidation and regulated by multiple cell metabolic pathways, including redox homeostasis, iron metabolism, mitochondrial activity, and the metabolism of amino acids, lipids, and sugars. Many organ injuries and degenerative pathologies are caused by ferroptosis. Ferroptosis is closely related to central nervous system injury diseases and is currently an important topic of research globally. This research examined the relationships between ferroptosis and the occurrence and treatment of central nervous system injury diseases. Additionally, ferroptosis was assessed from the aspect of theory proposal, mechanism of action, and related signaling pathways per recent research. This review provides a relevant theoretical basis for further research on this theory, the prospect of its development, and the prevention and treatment of such diseases.

How to Use the Cuprizone Model to Study De- and Remyelination

Multiple sclerosis (MS) is an autoimmune and inflammatory disorder affecting the central nervous system whose cause is still largely unknown. Oligodendrocyte degeneration results in demyelination of axons, which can eventually be repaired by a mechanism called remyelination. Prevention of demyelination and the pharmacological support of remyelination are two promising strategies to ameliorate disease progression in MS patients. The cuprizone model is commonly employed to investigate oligodendrocyte degeneration mechanisms or to explore remyelination pathways. During the last decades, several different protocols have been applied, and all have their pros and cons. This article intends to offer guidance for conducting pre-clinical trials using the cuprizone model in mice, focusing on discovering new treatment approaches to prevent oligodendrocyte degeneration or enhance remyelination.

The Therapeutic Mechanisms of Mesenchymal Stem Cells in MS-A Review Focusing on Neuroprotective Properties

In multiple sclerosis (MS), there is a great need for treatment with the ability to suppress compartmentalized inflammation within the central nervous system (CNS) and to promote remyelination and regeneration. Mesenchymal stem cells (MSCs) represent a promising therapeutic option, as they have been shown to migrate to the site of CNS injury and exert neuroprotective properties, including immunomodulation, neurotrophic factor secretion, and endogenous neural stem cell stimulation. This review summarizes the current understanding of the underlying neuroprotective mechanisms and discusses the translation of MSC transplantation and their derivatives from pre-clinical demyelinating models to clinical trials with MS patients.

Astrocytes: Lessons Learned from the Cuprizone Model

A diverse array of neurological and psychiatric disorders, including multiple sclerosis, Alzheimer's disease, and schizophrenia, exhibit distinct myelin abnormalities at both the molecular and histological levels. These aberrations are closely linked to dysfunction of oligodendrocytes and alterations in myelin structure, which may be pivotal factors contributing to the disconnection of brain regions and the resulting characteristic clinical impairments observed in these conditions. Astrocytes, which significantly outnumber neurons in the central nervous system by a five-to-one ratio, play indispensable roles in the development, maintenance, and overall well-being of neurons and oligodendrocytes. Consequently, they emerge as potential key players in the onset and progression of a myriad of neurological and psychiatric disorders. Furthermore, targeting astrocytes represents a promising avenue for therapeutic intervention in such disorders. To gain deeper insights into the functions of astrocytes in the context of myelin-related disorders, it is imperative to employ appropriate in vivo models that faithfully recapitulate specific aspects of complex human diseases in a reliable and reproducible manner. One such model is the cuprizone model, wherein metabolic dysfunction in oligodendrocytes initiates an early response involving microglia and astrocyte activation, culminating in multifocal demyelination. Remarkably, following the cessation of cuprizone intoxication, a spontaneous process of endogenous remyelination occurs. In this review article, we provide a historical overview of studies investigating the responses and putative functions of astrocytes in the cuprizone model. Following that, we list previously published works that illuminate various aspects of the biology and function of astrocytes in this multiple sclerosis model. Some of the studies are discussed in more detail in the context of astrocyte biology and pathology. Our objective is twofold: to provide an invaluable overview of this burgeoning field, and, more importantly, to inspire fellow researchers to embark on experimental investigations to elucidate the multifaceted functions of this pivotal glial cell subpopulation.

Research progress in the molecular mechanism of ferroptosis in Parkinson's disease and regulation by natural plant products

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder of the central nervous system after Alzheimer's disease. The current understanding of PD focuses mainly on the loss of dopamine neurons in the substantia nigra region of the midbrain, which is attributed to factors such as oxidative stress, alpha-synuclein aggregation, neuroinflammation, and mitochondrial dysfunction. These factors together contribute to the PD phenotype. Recent studies on PD pathology have introduced a new form of cell death known as ferroptosis. Pathological changes closely linked with ferroptosis have been seen in the brain tissues of PD patients, including alterations in iron metabolism, lipid peroxidation, and increased levels of reactive oxygen species. Preclinical research has demonstrated the neuroprotective qualities of certain iron chelators, antioxidants, Fer-1, and conditioners in Parkinson's disease. Natural plant products have shown significant potential in balancing ferroptosis-related factors and adjusting their expression levels. Therefore, it is vital to understand the mechanisms by which natural plant products inhibit ferroptosis and relieve PD symptoms. This review provides a comprehensive look at ferroptosis, its role in PD pathology, and the mechanisms underlying the therapeutic effects of natural plant products focused on ferroptosis. The insights from this review can serve as useful references for future research on novel ferroptosis inhibitors and lead compounds for PD treatment.

Research on ferroptosis as a therapeutic target for the treatment of neurodegenerative diseases

Ferroptosis is an iron- and lipid peroxidation (LPO)-mediated programmed cell death type. Recently, mounting evidence has indicated the involvement of ferroptosis in neurodegenerative diseases, especially in Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and so on. Treating ferroptosis presents opportunities as well as challenges for neurodegenerative diseases. This review provides a comprehensive overview of typical features of ferroptosis and the underlying mechanisms that contribute to its occurrence, as well as their implications in the pathogenesis and advancement of major neurodegenerative disorders. Meanwhile, we summarize the utilization of ferroptosis inhibition in both experimental and clinical approaches for the treatment of major neurodegenerative disorders. In addition, we specifically summarize recent advances in developing therapeutic means targeting ferroptosis in these diseases, which may guide future approaches for the effective management of these devastating medical conditions.

Iron in multiple sclerosis - Neuropathology, immunology, and real-world considerations

Iron is an essential element involved in a multitude of bodily processes. It is tightly regulated, as elevated deposition in tissues is associated with diseases such as multiple sclerosis (MS). Iron accumulation in the central nervous system (CNS) of MS patients is linked to neurotoxicity through mechanisms including oxidative stress, glutamate excitotoxicity, misfolding of proteins, and ferroptosis. In the past decade, the combination of MRI and histopathology has enhanced our understanding of iron deposition in MS pathophysiology, including in the pro-inflammatory and neurotoxicity of iron-laden rims of chronic active lesions. In this regard, iron accumulation may not only have an impact on different CNS-resident cells but may also promote the innate and adaptive immune dysfunctions in MS. Although there are discordant results, most studies indicate lower levels of iron but higher amounts of the iron storage molecule ferritin in the circulation of people with MS. Considering the importance of iron, there is a need for evidence-guided recommendation for dietary intake in people living with MS. Potential novel therapeutic approaches include the regulation of iron levels using next generation iron chelators, as well as therapies to interfere with toxic consequences of iron overload including antioxidants in MS.

Ferroptosis in Neurological Disease

Iron accumulation in the CNS occurs in many neurological disorders. It can contribute to neuropathology as iron is a redox-active metal that can generate free radicals. The reasons for the iron buildup in these conditions are varied and depend on which aspects of iron influx, efflux, or sequestration that help maintain iron homeostasis are dysregulated. Iron was shown recently to induce cell death and damage via lipid peroxidation under conditions in which there is deficient glutathione-dependent antioxidant defense. This form of cell death is called ferroptosis. Iron chelation has had limited success in the treatment of neurological disease. There is therefore much interest in ferroptosis as it potentially offers new drugs that could be more effective in reducing iron-mediated lipid peroxidation within the lipid-rich environment of the CNS. In this review, we focus on the molecular mechanisms that induce ferroptosis. We also address how iron enters and leaves the CNS, as well as the evidence for ferroptosis in several neurological disorders. Finally, we highlight biomarkers of ferroptosis and potential therapeutic strategies.

Sex Chromosomes and Gonads Shape the Sex-Biased Transcriptomic Landscape in Tlr7-Mediated Demyelination During Aging

Demyelination occurs in aging and associated diseases, including Alzheimer's disease. Several of these diseases exhibit sex differences in prevalence and severity. Biological sex primarily stems from sex chromosomes and gonads releasing sex hormones. To dissect mechanisms underlying sex differences in demyelination of aging brains, we constructed a transcriptomic atlas of cell type-specific responses to illustrate how sex chromosomes, gonads, and their interaction shape responses to demyelination. We found that sex-biased oligodendrocyte and microglial responses are driven by interaction of sex chromosomes and gonads prior to myelin loss. Post demyelination, sex chromosomes mainly guide microglial responses, while gonadal composition influences oligodendrocyte signaling. Significantly, ablation of the X-linked gene Toll-like receptor 7 (Tlr7), which exhibited sex-biased expression during demyelination, abolished the sex-biased responses and protected against demyelination.

Ferroptosis contributes to multiple sclerosis and its pharmacological targeting suppresses experimental disease progression

Multiple sclerosis (MS) is a chronic autoimmune disorder characterized by central nervous (CNS) demyelination resulting in axonal injury and neurological deficits. Essentially, MS is driven by an auto-amplifying mechanism of inflammation and cell death. Current therapies mainly focus on disease modification by immunosuppression, while no treatment specifically focuses on controlling cell death injury. Here, we report that ferroptosis, an iron-catalyzed mode of regulated cell death (RCD), contributes to MS disease progression. Active and chronic MS lesions and cerebrospinal fluid (CSF) of MS patients revealed several signs of ferroptosis, reflected by the presence of elevated levels of (labile) iron, peroxidized phospholipids and lipid degradation products. Treatment with our candidate lead ferroptosis inhibitor, UAMC-3203, strongly delays relapse and ameliorates disease progression in a preclinical model of relapsing-remitting MS. In conclusion, the results identify ferroptosis as a detrimental and targetable factor in MS. These findings create novel treatment options for MS patients, along with current immunosuppressive strategies.

Ferroptosis: A potential therapeutic target in autoimmune disease (Review)

Ferroptosis is a distinct type of regulated cell death characterized by iron overload and lipid peroxidation. Ferroptosis is regulated by numerous factors and controlled by several mechanisms. This cell death type has a relationship with the immune system, which may be regulated by damage-associated molecular patterns. Ferroptosis participates in the progression of autoimmune diseases, including autoimmune hepatitis, rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, multiple sclerosis, Parkinson's Disease, psoriasis and insulin-dependent diabetes mellitus. The present review summarizes the role of ferroptosis in autoimmune disorders and discusses ferroptosis as a potential therapeutic target for autoimmune disease.

Cuprizone drives divergent neuropathological changes in different mouse models of Alzheimer's disease

Myelin degradation is a normal feature of brain aging that accelerates in Alzheimer's disease (AD). To date, however, the underlying biological basis of this correlation remains elusive. The amyloid cascade hypothesis predicts that demyelination is caused by increased levels of the β-amyloid (Aβ) peptide. Here we report on work supporting the alternative hypothesis that early demyelination is upstream of amyloid. We challenged two different mouse models of AD (R1.40 and APP/PS1) using cuprizone-induced demyelination and tracked the responses with both neuroimaging and neuropathology. In oppose to amyloid cascade hypothesis, R1.40 mice, carrying only a single human mutant APP (Swedish; APP SWE ) transgene, showed a more abnormal changes of magnetization transfer ratio and diffusivity than in APP/PS1 mice, which carry both APP SWE and a second PSEN1 transgene (delta exon 9; PSEN1 dE9 ). Although cuprizone targets oligodendrocytes (OL), magnetic resonance spectroscopy and targeted RNA-seq data in R1.40 mice suggested a possible metabolic alternation in axons. In support of alternative hypotheses, cuprizone induced significant intraneuronal amyloid deposition in young APP/PS1, but not in R1.40 mice, and it suggested the presence of PSEN deficiencies, may accelerate Aβ deposition upon demyelination. In APP/PS1, mature OL is highly vulnerable to cuprizone with significant DNA double strand breaks (53BP1 + ) formation. Despite these major changes in myelin, OLs, and Aβ immunoreactivity, no cognitive impairment or hippocampal pathology was detected in APP/PS1 mice after cuprizone treatment. Together, our data supports the hypothesis that myelin loss can be the cause, but not the consequence, of AD pathology.

SIGNIFICANCE STATEMENT

The causal relationship between early myelin loss and the progression of Alzheimer's disease remains unclear. Using two different AD mouse models, R1.40 and APP/PS1, our study supports the hypothesis that myelin abnormalities are upstream of amyloid production and deposition. We find that acute demyelination initiates intraneuronal amyloid deposition in the frontal cortex. Further, the loss of oligodendrocytes, coupled with the accelerated intraneuronal amyloid deposition, interferes with myelin tract diffusivity at a stage before any hippocampus pathology or cognitive impairments occur. We propose that myelin loss could be the cause, not the consequence, of amyloid pathology during the early stages of Alzheimer's disease.

Ferroptosis induces detrimental effects in chronic EAE and its implications for progressive MS

Ferroptosis is a form of lipid peroxidation-mediated cell death and damage triggered by excess iron and insufficiency in the glutathione antioxidant pathway. Oxidative stress is thought to play a crucial role in progressive forms of multiple sclerosis (MS) in which iron deposition occurs. In this study we assessed if ferroptosis plays a role in a chronic form of experimental autoimmune encephalomyelitis (CH-EAE), a mouse model used to study MS. Changes were detected in the mRNA levels of several ferroptosis genes in CH-EAE but not in relapsing-remitting EAE. At the protein level, expression of iron importers is increased in the earlier stages of CH-EAE (onset and peak). While expression of hemoxygenase-1, which mobilizes iron from heme, likely from phagocytosed material, is increased in macrophages at the peak and progressive stages. Excess iron in cells is stored safely in ferritin, which increases with disease progression. Harmful, redox active iron is released from ferritin when shuttled to autophagosomes by 'nuclear receptor coactivator 4' (NCOA4). NCOA4 expression increases at the peak and progressive stages of CH-EAE and accompanied by increase in redox active ferrous iron. These changes occur in parallel with reduction in the antioxidant pathway (system xCT, glutathione peroxidase 4 and glutathione), and accompanied by increased lipid peroxidation. Mice treated with a ferroptosis inhibitor for 2 weeks starting at the peak of CH-EAE paralysis, show significant improvements in function and pathology. Autopsy samples of tissue sections of secondary progressive MS (SPMS) showed NCOA4 expression in macrophages and oligodendrocytes along the rim of mixed active/inactive lesions, where ferritin+ and iron containing cells are located. Cells expressing NCOA4 express less ferritin, suggesting ferritin degradation and release of redox active iron, as indicated by increased lipid peroxidation. These data suggest that ferroptosis is likely to contribute to pathogenesis in CH-EAE and SPMS.

Mechanisms of metabolic stress induced cell death of human oligodendrocytes: relevance for progressive multiple sclerosis

Oligodendrocyte (OL) injury and loss are central features of evolving lesions in multiple sclerosis. Potential causative mechanisms of OL loss include metabolic stress within the lesion microenvironment. Here we use the injury response of primary human OLs (hOLs) to metabolic stress (reduced glucose/nutrients) in vitro to help define the basis for the in situ features of OLs in cases of MS. Under metabolic stress in vitro, we detected reduction in ATP levels per cell that precede changes in survival. Autophagy was initially activated, although ATP levels were not altered by inhibitors (chloroquine) or activators (Torin-1). Prolonged stress resulted in autophagy failure, documented by non-fusion of autophagosomes and lysosomes. Consistent with our in vitro results, we detected higher expression of LC3, a marker of autophagosomes in OLs, in MS lesions compared to controls. Both in vitro and in situ, we observe a reduction in nuclear size of remaining OLs. Prolonged stress resulted in increased ROS and cleavage of spectrin, a target of Ca²⁺-dependent proteases. Cell death was however not prevented by inhibitors of ferroptosis or MPT-driven necrosis, the regulated cell death (RCD) pathways most likely to be activated by metabolic stress. hOLs have decreased expression of VDAC1, VDAC2, and of genes regulating iron accumulation and cyclophilin. RNA sequencing analyses did not identify activation of these RCD pathways in vitro or in MS cases. We conclude that this distinct response of hOLs, including resistance to RCD, reflects the combined impact of autophagy failure, increased ROS, and calcium influx, resulting in metabolic collapse and degeneration of cellular structural integrity. Defining the basis of OL injury and death provides guidance for development of neuro-protective strategies.

Сhanges of trace elements in the cerebellum and their influence on the rats behavior in elevated plus maze in the acute period of mild blast-induced brain injury

BACKGROUND

In connection with the widespread use of explosive devices in military conflicts, in particular in Ukraine, is relevant to detect the biometals changes in the cerebellum and determine the presence of their influence on the behavior changes of rats in the elevated plus maze in the acute period of a mild blast-traumatic brain injury (bTBI).

METHODS

The selected rats were randomly divided into 3 groups: Group I - Experimental with bTBI (with an excess pressure of 26-36 kPa), Group II - Sham and Group III - Intact. Behavior studies was in the elevated plus maze. Brain spectral analysis was with using of energy dispersive X-ray fluorescence analysis, after obtaining the quantitative mass fractions of biometals, the ratios of Cu/Fe, Cu/Zn, Zn/Fe were calculated and the data between the three groups were compared.

RESULTS

The results showed an increase in mobility in the experimental rats, which indicates functional disorders of the cerebellum in the form of maladaptation in space. Changes in cognitive activity also is an evidence of cerebellum suppression, which is indicated by changes in vertical locomotor activity. Grooming time was shortened. We established a significant increase in Cu/Fe and Zn/Fe ratios in the cerebellum, a decrease in Cu/Zn.

CONCLUSIONS

Changes in the Cu/Fe, Cu/Zn, and Zn/Fe ratios in the cerebellum correlate with impaired locomotor and cognitive activity in rats in the acute posttraumatic period. Accumulation of Fe on the 1st and 3rd day leads to disturbance of the Cu and Zn balance on the 7th day and starts a "vicious cycle" of neuronal damage. Cu/Fe, Cu/Zn, and Zn/Fe imbalances are secondary factors in the pathogenesis of brain damage as a result of primary bTBI.

Ferroptosis and the bidirectional regulatory factor p53

Ferroptosis is a type of regulated cell death characterized by iron-mediated lipid peroxidation, in contrast with apoptosis, autophagy, and necrosis. It can be triggered by many pathological processes, including cellular metabolism, tumors, neurodegenerative diseases, cardiovascular diseases, and ischemia-reperfusion injuries. In recent years, ferroptosis has been discovered to be associated with p53. P53 is a tumor suppressor protein with multiple and powerful functions in cell cycle arrest, senescence, cell death, repair of DNA damage, and mitophagy. Emerging evidence shows that ferroptosis plays a crucial role in tumor suppression by p53. P53 functions as a key bidirectional regulator of ferroptosis by adjusting metabolism of iron, lipids, glutathione peroxidase 4, reactive oxygen species, and amino acids via a canonical pathway. In addition, a noncanonical pathway of p53 that regulates ferroptosis has been discovered in recent years. The specific details require to be further clarified. These mechanisms provide new ideas for clinical applications, and translational studies of ferroptosis have been performed to treat various diseases.

The Cuprizone Mouse Model: A Comparative Study of Cuprizone Formulations from Different Manufacturers

The Cuprizone mouse model is widely used in studies on de- and remyelination. In the hands of different experimenters, the Cuprizone concentrations that lead to comparable levels of demyelination differ considerably. The reasons for this variability are unknown. In this study, we tested whether different Cuprizone formulations from different vendors and manufacturers influenced Cuprizone-induced histopathological hallmarks. We intoxicated male C57BL/6 mice with six Cuprizone powders that differed in their manufacturer, vendor, and purity. After five weeks, we analyzed the body weight changes over the course of the experiment, as well as the demyelination, astrogliosis, microgliosis and axonal damage by histological LFB-PAS staining and immunohistochemical labelling of PLP, IBA1, GFAP and APP. All Cuprizone formulations induced demyelination, astrogliosis, microgliosis, axonal damage and a moderate drop in body weight at the beginning of the intoxication period. In a cumulative evaluation of all analyses, two Cuprizone formulations performed weaker than the other formulations. In conclusion, all tested formulations did work, but the choice of Cuprizone formulation may have been responsible for the considerable variability in the experimental outcomes.

lThyroid hormone transporter Mct8/Oatp1c1 deficiency compromises proper oligodendrocyte maturation in the mouse CNS

Proper CNS myelination depends on the timed availability of thyroid hormone (TH) that induces differentiation of oligodendrocyte precursor cells (OPCs) to mature, myelinating oligodendrocytes. Abnormal myelination is frequently observed in Allan-Herndon-Dudley syndrome caused by inactivating mutations in the TH transporter MCT8. Likewise, persistent hypomyelination is a key CNS feature of the Mct8/Oatp1c1 double knockout (Dko) mouse model, a well-established mouse model for human MCT8 deficiency that exhibits diminished TH transport across brain barriers and thus a TH deficient CNS. Here, we explored whether decreased myelin content is caused by an impairment in oligodendrocyte maturation. To that end, we studied OPC and oligodendrocyte populations in Dko mice versus wild-type and single TH transporter knockout animals at different developmental time points (at postnatal days P12, P30, and P120) using multi-marker immunostaining and confocal microscopy. Only in Dko mice we observed a reduction in cells expressing the oligodendroglia marker Olig2, encompassing all stages between OPCs and mature oligodendrocytes. Moreover, Dko mice exhibited at all analysed time points an increased portion of OPCs and a reduced number of mature oligodendrocytes both in white and grey matter regions indicating a differentiation blockage in the absence of Mct8/Oatp1c1. We also assessed cortical oligodendrocyte structural parameters by visualizing and counting the number of mature myelin sheaths formed per oligodendrocyte. Again, only Dko mice displayed a reduced number of myelin sheaths that in turn exhibited an increase in length indicating a compensatory response to the reduced number of mature oligodendrocyte. Altogether, our studies underscore an oligodendrocyte differentiation impairment and altered oligodendrocyte structural parameters in the global absence of Mct8 and Oatp1c1. Both mechanisms most likely do not only cause the abnormal myelination state but also contribute to compromised neuronal functionality in Mct8/Oatp1c1 deficient animals.

Quercetin prevents the ferroptosis of OPCs by inhibiting the Id2/transferrin pathway

Spinal cord injury (SCI) is a destructive neurological disorder that causes impaired mobility, sensory, and autonomic dysfunctions. The loss of oligodendrocyte progenitor cells (OPCs), which can differentiate into mature oligodendrocytes and re-myelinate damaged axons, is related to poorer recovery for SCI patients. However, inhibiting OPCs loss has always been a difficult problem to overcome. In this study, we demonstrated the anti-ferroptosis effects of quercetin as a mechanism in erastin-induced OPC ferroptosis. Quercetin ameliorated erastin-induced ferroptosis in OPCs, as indicated by decreased iron concentration, reactive oxygen species (ROS) production, and increased content of glutathione (GSH) as well as more normal mitochondria morphology. Compared with erastin-induced OPCs, the myelin basic protein (MBP)-positive myelin and NF200-positive axonal was remarkably increased in quercetin-treated OPCs. Furthermore, quercetin ameliorated the erastin-induced ferroptosis as well as the myelin and axon loss of OPCs by downregulating transferrin. Transfected OPCs with transferrin overexpression plasmids significantly abrogated the protective role of quercetin in OPC ferroptosis. Using ChIP-qPCR, a direct interaction of transferrin with its upstream gene Id2 was found. The overexpression of Id2 reversed the effect of quercetin on OPC ferroptosis. In vivo study found that quercetin greatly decreased the area of injury, and enhanced the BBB score after SCI. Furthermore, in the SCI model, quercetin significantly downregulated Id2 and transferrin expression, while significantly up-regulated GPX4 and PTGS2 expression. In conclusion, quercetin prevents the ferroptosis of OPCs by inhibiting the Id2/transferrin pathway. These findings highlight quercetin as an anti-ferroptosis agent for the treatment or prevention of spinal cord injury.

Research Models to Study Ferroptosis's Impact in Neurodegenerative Diseases

Ferroptosis is a type of regulated cell death promoted by the appearance of oxidative perturbations in the intracellular microenvironment constitutively controlled by glutathione peroxidase 4 (GPX4). It is characterized by increased production of reactive oxygen species, intracellular iron accumulation, lipid peroxidation, inhibition of system Xc-, glutathione depletion, and decreased GPX4 activity. Several pieces of evidence support the involvement of ferroptosis in distinct neurodegenerative diseases. In vitro and in vivo models allow a reliable transition to clinical studies. Several in vitro models, including differentiated SH-SY5Y and PC12 cells, among others, have been used to investigate the pathophysiological mechanisms of distinct neurodegenerative diseases, including ferroptosis. In addition, they can be useful in the development of potential ferroptosis inhibitors that can be used as disease-modifying drugs for the treatment of such diseases. On the other hand, in vivo models based on the manipulation of rodents and invertebrate animals, such as Drosophila melanogaster, Caenorhabditis elegans, and zebrafish, have been increasingly used for research in neurodegeneration. This work provides an up-to-date review of the main in vitro and in vivo models that can be used to evaluate ferroptosis in the most prevalent neurodegenerative diseases, and to explore potential new drug targets and novel drug candidates for effective disease-modifying therapies.

Emerging insights into the role of ferroptosis in the pathogenesis of autoimmune diseases

Ferroptosis, a novel type of regulated cell death mediated by iron-dependent lipid oxidation, was discovered a decade ago. Significant progress has been made in our knowledge of ferroptosis and immune dysfunction. This review covers recent advancements in the interaction of ferroptosis and the immune system, with an emphasis on autoimmune diseases. The critical regulators of ferroptosis are summarized in the context of reactive oxygen species biology, lipid metabolism, and iron homeostasis. The molecular crosstalk between ferroptosis and different immune cells is also highlighted. Future research is expected to yield new insights into the mechanisms governing ferroptosis and its potential therapeutic benefits in autoimmune diseases.

Current, emerging, and potential therapies for non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) has been identified as the most common chronic liver disease worldwide, with a growing incidence. NAFLD is considered the hepatic manifestation of a metabolic syndrome that emerges from multiple factors (e.g., oxidative stress, metabolic disorders, endoplasmic reticulum stress, cell death, and inflammation). Non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, has been reported to be a leading cause of cirrhosis and hepatic carcinoma, and it is progressing rapidly. Since there is no approved pharmacotherapy for NASH, a considerable number of therapeutic targets have emerged with the deepening of the research on NASH pathogenesis. In this study, the therapeutic potential and properties of regulating metabolism, the gut microbiome, antioxidant, microRNA, inhibiting apoptosis, targeting ferroptosis, and stem cell-based therapy in NASH are reviewed and evaluated. Since the single-drug treatment of NASH is affected by individual heterogeneous responses and side effects, it is imperative to precisely carry out targeted therapy with low toxicity. Lastly, targeted therapeutic agent delivery based on exosomes is proposed in this study, such that drugs with different mechanisms can be incorporated to generate high-efficiency and low-toxicity individualized medicine.

Identification of Key Ferroptosis-Related Genes in the Peripheral Blood of Patients with Relapsing-Remitting Multiple Sclerosis and Its Diagnostic Value

Multiple sclerosis (MS) is a neurodegenerative disease with a complex pathogenesis. Re-lapsing-remitting multiple sclerosis (RRMS) is the most common subset of MS, accounting for approximately 85% of cases. Recent studies have shown that ferroptosis may contribute to the progression of RRMS, but the underlying mechanism remains to be elucidated. Herein, this study intended to explore the molecular network of ferroptosis associated with RRMS and establish a predictive model for efficacy diagnosis. Firstly, RRMS-related module genes were identified using weighted gene co-expression network analysis (WGCNA). Secondly, the optimal machine learning model was selected from four options: the generalized linear model (GLM), random forest model (RF), support vector machine model (SVM), and extreme gradient boosting model (XGB). Subsequently, the predictive efficacy of the diagnostic model was evaluated using receiver operator characteristic (ROC) analysis. Finally, a SVM diagnostic model based on five genes (JUN, TXNIP, NCOA4, EIF2AK4, PIK3CA) was established, and it demonstrated good predictive performance in the validation dataset. In summary, our study provides a systematic exploration of the complex relationship between ferroptosis and RRMS, which may contribute to a better understanding of the role of ferroptosis in the pathogenesis of RRMS and provide promising diagnostic strategies for RRMS patients.

The role of iron metabolism in the pathogenesis and treatment of multiple sclerosis

Multiple sclerosis is a severe demyelinating disease mediated by cells of the innate and adaptive immune system, especially pathogenic T lymphocytes that produce the pro-inflammatory cytokine granulocyte-macrophage colony stimulating factor (GM-CSF). Although the factors and molecules that drive the genesis of these cells are not completely known, some were discovered and shown to promote the development of such cells, such as dietary factors. In this regard, iron, the most abundant chemical element on Earth, has been implicated in the development of pathogenic T lymphocytes and in MS development via its effects on neurons and glia. Therefore, the aim of this paper is to revise the state-of-art regarding the role of iron metabolism in cells of key importance to MS pathophysiology, such as pathogenic CD4+ T cells and CNS resident cells. Harnessing the knowledge of iron metabolism may aid in the discovery of new molecular targets and in the development of new drugs that tackle MS and other diseases that share similar pathophysiology.

Molecular mechanisms of ferroptosis and their involvement in brain diseases

Ferroptosis is a type of regulated cell death characterized by intracellular accumulation of iron and reactive oxygen species, inhibition of system Xc-, glutathione depletion, nicotinamide adenine dinucleotide phosphate oxidation and lipid peroxidation. Since its discovery and characterization in 2012, many efforts have been made to reveal the underlying mechanisms, modulating compounds, and its involvement in disease pathways. Ferroptosis inducers include erastin, sorafenib, sulfasalazine and glutamate, which, by inhibiting system Xc-, prevent the import of cysteine into the cells. RSL3, statins, Ml162 and Ml210 induce ferroptosis by inhibiting glutathione peroxidase 4 (GPX4), which is responsible for preventing the formation of lipid peroxides, and FIN56 and withaferin trigger GPX4 degradation. On the other side, ferroptosis inhibitors include ferrostatin-1, liproxstatin-1, α-tocopherol, zileuton, FSP1, CoQ10 and BH4, which interrupt the lipid peroxidation cascade. Additionally, deferoxamine, deferiprone and N-acetylcysteine, by targeting other cellular pathways, have also been classified as ferroptosis inhibitors. Increased evidence has established the involvement of ferroptosis in distinct brain diseases, including Alzheimer's, Parkinson's and Huntington's diseases, amyotrophic lateral sclerosis, multiple sclerosis, and Friedreich's ataxia. Thus, a deep understanding of how ferroptosis contributes to these diseases, and how it can be modulated, can open a new window of opportunities for novel therapeutic strategies and targets. Other studies have shown a sensitivity of cancer cells with mutated RAS to ferroptosis induction and that chemotherapeutic agents and ferroptosis inducers synergize in tumor treatment. Thus, it is tempting to consider that ferroptosis may arise as a target mechanistic pathway for the treatment of brain tumors. Therefore, this work provides an up-to-date review on the molecular and cellular mechanisms of ferroptosis and their involvement in brain diseases. In addition, information on the main ferroptosis inducers and inhibitors and their molecular targets is also provided.

Iron Overload Causes Ferroptosis But Not Apoptosis in MO3.13 Oligodendrocytes

Oligodendrocytes are the most iron-rich cells in the brain. Studies have shown that oligodendrocytes are very sensitive to oxidative stress, and iron overload is more likely to cause damage to oligodendrocytes. The purpose of this experiment was to investigate the damaging effect and mechanism of ferric ammonium citrate (FAC) on MO3.13 oligodendrocytes. In FAC treatment group, the intracellular iron concentration and intracellular reactive oxygen species were increased. There were no obvious changes in nucleus and chromatin, but increased mitochondrial membrane density, decreased mitochondrial cristae and mitochondrial length were observed. Glutathione peroxidase 4 (GPX4) expression was decreased, but the ratio of Bcl-2/Bax protein levels and cleaved caspase-3 expression did not change. Moreover, the iron chelator deferoxamine (DFO) and the ferroptosis inhibitor ferrostatin-1(Fer-1) could inhibit the upregulation of GPX4, which indicating that DFO and Fer-1 could inhibit ferroptosis in MO3.13 oligodendrocytes induced by iron overload. Furthermore, the phosphorylation level of p53 was not changed, while the ratio of protein expressions of p-Erk1/2/Erk1/2 were markedly increased. Taken together, our data suggest that iron overload induces ferroptosis but not apoptosis in oligodendrocytes. The mechanism may be related to mitogen-activated protein kinase pathway activation rather than p53 pathway activation.

Amelioration of White Matter Injury Through Mitigating Ferroptosis Following Hepcidin Treatment After Spinal Cord Injury

Spinal cord injury (SCI) usually introduces permanent or long-lasting neurological impairments. Maintaining the integrity of the limited number of white matter bundles (5-10%) preserves wholly or partially locomotor following SCI. Considering that the basic structure of white matter bundles is axon wrapped by oligodendrocytes, promoting oligodendrocytes survival might be a feasible strategy for reducing white matter injury (WMI) after SCI. Oligodendrocytes are rich in unsaturated fatty acid and susceptible to ferroptosis-induced damage. Hence, exploring method to reduce ferroptosis is supposed to expedite oligodendrocytes survival, thereafter mitigating WMI to facilitate functional recovery post-SCI. Here, the results indicated the administration of hepcidin reduced iron accumulation to promote oligodendrocytes survival and to decrease spinal cord atrophy, therefore facilitating functional recovery. Then, the WMI was evidently decreased owing to attenuating ferroptosis. Subsequently, the results revealed that the expression of divalent metal transporter 1 (DMT1) and transferrin receptor (TfR) was expressed in CC1⁺ cells. The expression level of DMT1 and TfR was significantly increased, while this phenomenon was obviously neutralized with the administration of hepcidin in the epicenter of spinal cord after SCI. Afterward, the application of hepcidin downregulated reactive oxygen species (ROS) overload, which was evidently increased with the treatment of 20 μM FeCl₃, therefore increasing cell viability and reducing lactate dehydrogenase (LDH) activity through downregulating the expression of DMT1 and TfR to inhibit ferroptosis in oligodendrocyte progenitor cells (OPCs). The present study provides evidence that the application of hepcidin facilitates oligodendrocytes survival to alleviate WMI via reducing the expression of DMT1 and TfR.

Intranasal Lipid Nanoparticles Containing Bioactive Compounds Obtained from Marine Sources to Manage Neurodegenerative Diseases

Marine sources contain several bioactive compounds with high therapeutic potential, such as remarkable antioxidant activity that can reduce oxidative stress related to the pathogenesis of neurodegenerative diseases. Indeed, there has been a growing interest in these natural sources, especially those resulting from the processing of marine organisms (i.e., marine bio-waste), to obtain natural antioxidants as an alternative to synthetic antioxidants in a sustainable approach to promote circularity by recovering and creating value from these bio-wastes. However, despite their expected potential to prevent, delay, or treat neurodegenerative diseases, antioxidant compounds may have difficulty reaching the brain due to the need to cross the blood–brain barrier (BBB). In this regard, alternative delivery systems administered by different routes have been proposed, including intranasal administration of lipid nanoparticles, such as solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), which have shown promising results. Intranasal administration shows several advantages, including the fact that molecules do not need to cross the BBB to reach the central nervous system (CNS), as they can be transported directly from the nasal cavity to the brain (i.e., nose-to-brain transport). The benefits of using SLN and NLC for intranasal delivery of natural bioactive compounds for the treatment of neurodegenerative diseases have shown relevant outcomes through in vitro and in vivo studies. Noteworthy, for bioactive compounds obtained from marine bio-waste, few studies have been reported, showing the open potential of this research area. This review updates the state of the art of using SLN and NLC to transport bioactive compounds from different sources, in particular, those obtained from marine bio-waste, and their potential application in the treatment of neurodegenerative diseases.