6-Hydroxydopamine Induces Abnormal Iron Sequestration in BV2 Microglia by Activating Iron Regulatory Protein 1 and Inhibiting Hepcidin Release

Targeting ferroptosis in the neurovascular unit: A promising approach for treating diabetic cognitive impairment

The cognitive decline associated with chronic metabolic disease diabetes has garnered extensive scrutiny, yet its pathogenesis remains incompletely understood, and the advancement of targeted therapeutics has posed a persistent challenge. Ferroptosis, a novel form of cell death characterized by intracellular lipid peroxidation and iron overload, has recently emerged as a significant factor. Numerous contemporary studies have corroborated that ferroptosis within the neurovascular unit is intimately associated with the onset of diabetes-induced cognitive impairment. Numerous contemporary studies have corroborated that ferroptosis within the neurovascular unit is intimately associated with the onset of diabetic cognitive impairment (DCI). This article initially conducts a profound analysis of the mechanism of ferroptosis, followed by a detailed elucidation of the specific manifestations of neurovascular unit ferroptosis in the context of diabetic cognitive function impairment. Furthermore, an exhaustive review of pertinent literature from April 2020 to March 2024 has been undertaken, resulting in the selection of 31 documents of significant reference value. These documents encompass studies on 11 distinct drugs, all of which are centered around investigating methods to inhibit the ferroptosis pathway as a potential treatment for DCI. Simultaneously, we conducted a review of 12 supplementary literary sources that presented 10 pharmacological agents with anti-ferroptosis properties in other neurodegenerative disorders. This article critically examines the potential influence of neurovascular unit ferroptosis on the progression of cognitive impairment in diabetes, from the three aforementioned perspectives, and organizes the existing and potential therapeutic drugs. It is our aspiration that this article will serve as a theoretical foundation for scholars in related disciplines when conceptualizing, investigating, and developing novel clinical drugs for DCI.

The role of iron transporters and regulators in Alzheimer's disease and Parkinson's disease: Pathophysiological insights and therapeutic prospects

Brain iron homeostasis plays a vital role in maintaining brain development and controlling neuronal function under physiological conditions. Many studies have shown that the imbalance of brain iron homeostasis is closely related to the pathogenesis of neurodegenerative diseases (NDs), such as Alzheimer's disease (AD) and Parkinson's disease (PD). Recent advances have revealed the importance of iron transporters and regulatory molecules in the pathogenesis and treatment of NDs. This review summarizes the research progress on brain iron overload and the aberrant expression of several key iron transporters and regulators in AD and PD, emphasizes the pathological roles of these molecules in the pathogenesis of AD and PD, and highlights the therapeutic prospects of targeting these iron transporters and regulators to restore brain iron homeostasis in the treatment of AD and PD. A comprehensive understanding of the pathophysiological roles of iron, iron transporters and regulators, and their regulations in NDs may provide new therapeutic avenues for more targeted neurotherapeutic strategies for treating these diseases.

JWH133 attenuates behavior deficits and iron accumulation in 6-OHDA-induced Parkinson's disease model rats

Growing evidence indicates that activation of cannabinoid type 2 (CB2) receptors protects dopamine neurons in the pathogenesis of Parkinson's disease (PD). However, the mechanisms underlying neuroprotection mediated by CB2 receptors are still elusive. In this study, we investigated the effects of CB2 receptor activation on 6-hydroxydopamine (6-OHDA)-induced dopamine neuron degeneration and iron accumulation in the substantia nigra (SN) of rats. We found that treatment with JWH133, a selective CB2 receptor agonist, significantly improved the apomorphine (APO)-induced rotational behavior in 6-OHDA-treated rats. The decreased numbers of tyrosine hydroxylase (TH)-positive neurons and reduced TH protein expression in the lesioned SN of rats were effectively restored by JWH133. Moreover, we found that JWH133 inhibited the increase of iron-staining cells in the lesioned SN of rats. To explore the protective mechanisms of activation of CB2 receptors on dopamine neurons, we further observed the effect of JWH133 on 1-methyl-4-phenylpyridinium (MPP+)-treated primary cultured ventral mesencephalon (VM) neurons from rats. We found that JWH133 significantly inhibited the increase of intracellular reactive oxygen species (ROS), the activation of Caspase-3, the decrease of mitochondrial transmembrane potential (ΔΨm), and the decrease of Bcl-2/Bax protein expression caused by MPP+ treatment. JWH133 also inhibited the MPP+-induced upregulation of divalent metal transporter-1 (DMT1) and downregulation of ferroportin 1 (FPN1). Furthermore, JWH133 also suppressed the MPP+-accelerated iron influx in the VM neurons. These results suggest that activation of CB2 receptor suppresses MPP+-induced cellular iron accumulation and prevents neurodegeneration.NEW & NOTEWORTHY Expression of cannabinoid type 2 receptors (CB2Rs) was discovered on dopamine neurons in recent years. The role of CB2R expressed on dopamine neurons in the pathogenesis of Parkinson's disease (PD) has not been fully elucidated. The content of iron accumulation in the brain is closely related to the progress of PD. We verified the inhibitory effect of CB2R on iron deposition in dopamine neurons through experiments, which provided a new idea for the treatment of PD.

Alpha-synuclein affects certain iron transporters of BV2 microglia cell through its ferric reductase activity

Alpha-synuclein (α-syn) is a major component of Lewy bodies, which is a biomarker of Parkinson's disease (PD). It accumulates in substantia nigra pars compacta (SNpc) to form insoluble aggregates and cause neurotoxicity, which is often accompanied by iron deposition. We compared the iron reductase activity between monomeric α-syn (M-α-syn) and oligomeric α-syn (O-α-syn) and investigated the effect of α-syn on iron metabolism of BV2 microglia cells as well. α-syn had ferric reductase activity, and O-α-syn had stronger enzyme activity than M-α-syn. M-α-syn upregulated iron uptake protein, divalent metal transporter1 (DMT1) expression, and iron influx but did not regulate iron release protein ferroportin1 (FPN1) expression and iron efflux. O-α-syn elevated the expression of both DMT1 and FPN1 and thus increased the iron influx and efflux in BV2 microglial cells, but the expressions of iron regulatory protein1 (IRP1) and hypoxia-inducible factor 2α (HIF-2α) had no significant change. Moreover, both M-α-syn and O-α-syn could increase the mRNA expressions of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in BV2 microglia cells. Both types of α-syn can activate microglia, which leads to increased expressions of proinflammatory factors. α-syn can affect DMT1 and FPN1 expressions in BV2 microglia cells, which might be through its ferric reductase activity.NEW & NOTEWORTHY The effects of monomeric α-syn (M-α-syn) and oligomeric α-syn (O-α-syn) on the iron metabolism of BV2 microglia cells were detected by exogenous α-syn treatment. This study provides a strong experimental basis for α-syn involvement in iron metabolism in microglia.

A commentary on studies of brain iron accumulation during ageing

Brain iron content is widely reported to increase during "ageing", across multiple species from nematodes, rodents (mice and rats) and humans. Given the redox-active properties of iron, there has been a large research focus on iron-mediated oxidative stress as a contributor to tissue damage during natural ageing, and also as a risk factor for neurodegenerative disease. Surprisingly, however, the majority of published studies have not investigated brain iron homeostasis during the biological time period of senescence, and thus knowledge of how brain homeostasis changes during this critical stage of life largely remains unknown. This commentary examines the literature published on the topic of brain iron homeostasis during ageing, providing a critique on limitations of currently used experimental designs. The commentary also aims to highlight that although much research attention has been given to iron accumulation or iron overload as a pathological feature of ageing, there is evidence to support functional iron deficiency may exist, and this should not be overlooked in studies of ageing or neurodegenerative disease.

The potential significance of hepcidin evaluation in progressive supranuclear palsy

INTRODUCTION

Hepcidin is a peptide associated with controlling the distribution of iron in tissues. Growing interest is linked with its impact on neurodegenerative diseases, as disruption of the iron regulation may be considered an initiatory element of pathological protein accumulation. The possible impact of hepcidin was not previously sufficiently explored in progressive supranuclear palsy (PSP).

METHODS

Twelve patients with PSP-Richardson's syndrome (PSP-RS), 12 with PSP-Parkinsonism Predominant (PSP-P), and 12 controls were examined using Unified Parkinson's Disease Rating Scale-III part (UPDRS-III) in OFF stage and analyzed in the context of hepcidin levels in the serum.

RESULTS

The work revealed increased levels of hepcidin in PSP-RS when compared to PSP-P and controls. Moreover, hepcidin was found to be negatively correlated with UPDRS-III results in PSP-RS, whereas positively in PSP-P.

CONCLUSION

The work may suggest a possible impact of hepcidin in PSP, possibly differing depending on its subtype.

The Protection of EGCG Against 6-OHDA-Induced Oxidative Damage by Regulating PPARγ and Nrf2/HO-1 Signaling

6-Hydroxydopamine (6-OHDA) is a classic neurotoxin that has been widely used in Parkinson's disease research. 6-OHDA can increase intracellular reactive oxygen species (ROS) and can cause cell damage, which can be attenuated with (-)-Epigallocatechin-3-gallate (EGCG) treatment. However, the mechanism by which EGCG alters the 6-OHDA toxicity remains unclear; In this study, we found 6-OHDA (25 μM) alone increased intracellular ROS concentration in N27 cells, which was attenuated by pretreating with EGCG (100 μM). We evaluated the intracellular oxidative damage by determining the level of thiobarbituric acid reactive substances (TBARS) and protein carbonyl content. 6-OHDA significantly increased TBARS by 82.7% (P < .05) and protein carbonyl content by 47.8 (P < .05), compared to the control. Pretreatment of EGCG decreased TBARS and protein carbonyls by 36.4% (P < .001) and 27.7% (P < .05), respectively, compared to 6-OHDA alone treatment. Antioxidant effect was tested with E2-related factor 2 (Nrf2), heme oxygenase-1(HO-1) and peroxisome-proliferator activator receptor γ (PPARγ) expression. 6-OHDA increased Nrf2 expression by 69.6% (P < .001), HO-1 by 173.3% (P < .001), and PPARγ by 122.7% (P < .001), compared with untreatment. EGCG pretreatment stabilized these alterations induced by 6-OHDA. Our results suggested that the neurotoxicity of 6-OHDA in N27 cells was associated with ROS pathway, whereas pretreatment of EGCG suppressed the ROS generation and deactivated the Nrf2/HO-1 and PPARγ expression.

Brain Iron Homeostasis and Mental Disorders

Iron plays an essential role in various physiological processes. A disruption in iron homeostasis can lead to severe consequences, including impaired neurodevelopment, neurodegenerative disorders, stroke, and cancer. Interestingly, the link between mental health disorders and iron homeostasis has not received significant attention. Therefore, our understanding of iron metabolism in the context of psychological diseases is incomplete. In this review, we aim to discuss the pathologies and potential mechanisms that relate to iron homeostasis in associated mental disorders. We propose the hypothesis that maintaining brain iron homeostasis can support neuronal physiological functions by impacting key enzymatic activities during neurotransmission, redox balance, and myelination. In conclusion, our review highlights the importance of investigating the relationship between trace element nutrition and the pathological process of mental disorders, focusing on iron. This nutritional perspective can offer valuable insights for the clinical treatment of mental disorders.

Role of microglial metabolic reprogramming in Parkinson's disease

Parkinson's disease (PD) is a common age-related neurodegenerative disorder characterized by damage to nigrostriatal dopaminergic neurons. Key pathogenic mechanisms underlying PD include alpha-synuclein misfolding and aggregation, impaired protein clearance, mitochondrial dysfunction, oxidative stress, and neuroinflammation. However, to date, no study has confirmed the specific pathogenesis of PD. Similarly, current PD treatment methods still have shortcomings. Although some emerging therapies have proved effective for PD, the specific mechanism still needs further clarification. Metabolic reprogramming, a term first proposed by Warburg, is applied to the metabolic energy characteristics of tumor cells. Microglia have similar metabolic characteristics. Pro-inflammatory M1 type and anti-inflammatory M2 type are the two types of activated microglia, which exhibit different metabolic patterns in glucose, lipid, amino acid, and iron metabolism. Additionally, mitochondrial dysfunction may be involved in microglial metabolic reprogramming by activating various signaling mechanisms. Functional changes in microglia resulting from metabolic reprogramming can cause changes in the brain microenvironment, thus playing an important role in neuroinflammation or tissue repair. The involvement of microglial metabolic reprogramming in PD pathogenesis has been confirmed. Neuroinflammation and dopaminergic neuronal death can effectively be reduced by inhibiting certain metabolic pathways in M1 microglia or reverting M1 cells to the M2 phenotype. This review summarizes the relationship between microglial metabolic reprogramming and PD and provides strategies for PD treatment.

Evaluation of the therapeutic potential of cerebrolysin and/or lithium in the male Wistar rat model of Parkinson's disease induced by reserpine

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease worldwide and represents a challenge for clinicians. The present study aims to investigate the effects of cerebrolysin and/or lithium on the behavioral, neurochemical and histopathological alterations induced by reserpine as a model of PD. The rats were divided into control and reserpine-induced PD model groups. The model animals were further divided into four subgroups: rat PD model, rat PD model treated with cerebrolysin, rat PD model treated with lithium and rat PD model treated with a combination of cerebrolysin and lithium. Treatment with cerebrolysin and/or lithium ameliorated most of the alterations in oxidative stress parameters, acetylcholinesterase and monoamines in the striatum and midbrain of reserpine-induced PD model. It also ameliorated the changes in nuclear factor-kappa and improved the histopathological picture induced by reserpine. It could be suggested that cerebrolysin and/or lithium showed promising therapeutic potential against the variations induced in the reserpine model of PD. However, the ameliorating effects of lithium on the neurochemical, histopathological and behavioral alterations induced by reserpine were more prominent than those of cerebrolysin alone or combined with lithium. It can be concluded that the antioxidant and anti-inflammatory effects of both drugs played a significant role in their therapeutic potency.

Restraint Stress Exacerbates Apoptosis in a 6-OHDA Animal Model of Parkinson Disease

Activation of the apoptotic pathway has been associated with promoting neuronal cell death in the pathophysiology of Parkinson disease (PD). Nonetheless, the mechanisms by which it may occur remain unclear. It has been suggested that stress-induced oxidation and potential apoptosis may play a major role in the progression of PD. Thus, in this study, we aimed to investigate the effect of subchronic restraint stress on striatal dopaminergic activity, iron, p53, caspase-3, and plasmatic acetylcholinesterase (AChE) levels in male Wistar rat model of PD induced by administration of 6-hydroxydopamine (6-OHDA) in the medial forebrain bundle (MFB). The obtained results showed that restraint stress exacerbates motor coordination deficits and anxiety in animals treated with 6-OHDA in comparison to animals receiving saline, and it had no effect on object recognition memory. On another hand, 6-OHDA decreased dopamine (DA) levels, increased iron accumulation, and induced overexpression of the pro-apoptotic factors caspase-3, p53, and AChE. More interestingly, post-lesion restraint stress exacerbated the expression of caspase-3 and AChE without affecting p53 expression. These findings suggest that subchronic stress may accentuate apoptosis and may contribute to DA neuronal loss in the striatal regions and possibly exacerbate the progression of PD.

Ferroptosis and its role in skeletal muscle diseases

Ferroptosis is characterized by the accumulation of iron and lipid peroxidation products, which regulates physiological and pathological processes in numerous organs and tissues. A growing body of research suggests that ferroptosis is a key causative factor in a variety of skeletal muscle diseases, including sarcopenia, rhabdomyolysis, rhabdomyosarcoma, and exhaustive exercise-induced fatigue. However, the relationship between ferroptosis and various skeletal muscle diseases has not been investigated systematically. This review’s objective is to provide a comprehensive summary of the mechanisms and signaling factors that regulate ferroptosis, including lipid peroxidation, iron/heme, amino acid metabolism, and autophagy. In addition, we tease out the role of ferroptosis in the progression of different skeletal muscle diseases and ferroptosis as a potential target for the treatment of multiple skeletal muscle diseases. This review can provide valuable reference for the research on the pathogenesis of skeletal muscle diseases, as well as for clinical prevention and treatment.

New Target for Prevention and Treatment of Neuroinflammation: Microglia Iron Accumulation and Ferroptosis

Microglia play an important role in maintaining central nervous system homeostasis and are the major immune cells in the brain. In response to internal or external inflammatory stimuli, microglia are activated and release numerous inflammatory factors, thus leading to neuroinflammation. Inflammation and microglia iron accumulation promote each other and jointly promote the progression of neuroinflammation. Inhibiting microglia iron accumulation prevents neuroinflammation. Ferroptosis is an iron-dependent phospholipid peroxidation-driven type of cell death regulation. Cell iron accumulation causes the peroxidation of cell membrane phospholipids and damages the cell membrane. Ultimately, this process leads to cell ferroptosis. Iron accumulation or phospholipid peroxidation in microglia releases a large number of inflammatory factors. Thus, inhibiting microglia ferroptosis may be a new target for the prevention and treatment of neuroinflammation.