Astrocyte-derived hepcidin controls iron traffic at the blood-brain-barrier via regulating ferroportin 1 of microvascular endothelial cells

Iron metabolism dysfunction in neuropsychiatric disorders: Implications for therapeutic intervention

Iron is a trace metal that takes part in the maintenance of body homeostasis by, for instance, aiding in energy production and immunity. A body of evidence now demonstrates that dysfunction in iron metabolism can have detrimental effects and is intricately associated with the development of neuropsychiatric disorders, including Major Depressive Disorder (MDD), anxiety, and schizophrenia. For instance, changes in serum and central nervous system (CNS) levels of iron and in proteins mediating iron metabolism have been documented in patients grappling with the aforementioned diseases. By contrast, targeting iron metabolism by using iron chelators, for instance, has proven to be effective in alleviating disease burden. Therefore, here we review the state-of-the-art regarding the role of iron metabolism and its dysfunction in the context of neuropsychiatric disorders. Furthermore, we discuss how targeting iron metabolism can be an effective therapeutic option to tackle this class of diseases. Finally, we discuss the mechanisms linking this dysfunction to behavioral changes in these disorders. Harnessing the knowledge of iron metabolism is not only key to the characterization of novel molecular targets and disease biomarkers but also crucial to drug repurposing and drug design.

AGEING RESEARCH REVIEWS (ARR-D-24-01334R1) Metabolic dysfunction contributes to mood disorders after traumatic brain injury

Traumatic brain injury (TBI) presents significant risks concerning mortality and morbidity. Individuals who suffer from TBI may exhibit mood disorders, including anxiety and depression. Both preclinical and clinical research have established correlations between TBI and disturbances in the metabolism of amino acids, lipids, iron, zinc, and copper, which are implicated in the emergence of mood disorders post-TBI. The purpose of this review is to elucidate the impact of metabolic dysfunction on mood disorders following TBI and to explore potential strategies for mitigating anxiety and depression symptoms. We researched the PubMed and Web of Science databases to delineate the mechanisms by which metabolic dysfunction contributes to mood disorders in the context of TBI. Particular emphasis was placed on the roles of glutamate, kynurenine, lipids, iron, zinc, and copper metabolism. Metabolic dysfunction is linked to mood disorders post-TBI through multiple pathways, encompassing the glutamatergic system, the kynurenine pathway, endocannabinoids, iron deposition, iron-related ferroptosis, zinc deficiency, and copper dysregulation. Furthermore, this review addresses the influence of metabolic dysfunction on mood disorders in the elderly demographic following TBI. Targeting metabolic dysfunction for therapeutic intervention appears promising in alleviating symptoms of anxiety and depression that arise after TBI. While further investigation is warranted to delineate the underlying pathophysiologic mechanisms of mood disorders post-TBI, current evidence underscores the potential contribution of metabolic dysfunction to these conditions. Therefore, rectifying metabolic dysfunction represents a viable and strategic approach to addressing mood disorders following TBI.

An update on the role of ferroptosis in ischemic stroke: from molecular pathways to Neuroprotection

INTRODUCTION

Ischemic stroke (IS), a major cause of mortality and disability worldwide, remains a significant healthcare challenge due to limited therapeutic options. Ferroptosis, a distinct iron-dependent form of regulated cell death characterized by lipid peroxidation and oxidative stress, has emerged as a crucial mechanism in IS pathophysiology. This review explores the role of ferroptosis in IS and its potential for driving innovative therapeutic strategies.

AREA COVERED

This review delves into the practical implications of ferroptosis in IS, focusing on molecular mechanisms like lipid peroxidation, iron accumulation, and their interplay with inflammation, reactive oxygen species (ROS), and the Nrf2-ARE antioxidant system. It highlights ferroptotic proteins, small-molecule inhibitors, and non-coding RNA modulators as emerging therapeutic targets to mitigate neuroinflammation and neuronal cell death. Studies from PubMed (1982-2024) were identified using MeSH terms such as 'Ferroptosis' and 'Ischemic Stroke,' and only rigorously screened articles were included.

EXPERT OPINION

Despite preclinical evidence supporting the neuroprotective effects of ferroptosis inhibitors, clinical translation faces hurdles such as suboptimal pharmacokinetics and safety concerns. Advances in drug delivery systems, bioinformatics, and AI-driven drug discovery may optimize ferroptosis-targeting strategies, develop biomarkers, and improve therapeutic outcomes for IS patients.

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.

Ferritin loss in astrocytes reduces spinal cord oxidative stress and demyelination in the experimental autoimmune encephalomyelitis (EAE) model

Demyelinating diseases such as multiple sclerosis (MS) cause myelin degradation and oligodendrocyte death, resulting in the release of toxic iron and iron-induced oxidative stress. Astrocytes have a large capacity for iron transport and storage, however the role of astrocytic iron homeostasis in demyelinating disorders is not completely understood. Here we investigate whether astrocytic iron metabolism modulates neuroinflammation, oligodendrocyte survival, and oxidative stress following demyelination. To this aim, we conditionally knock out ferritin in astrocytes and induce experimental autoimmune encephalomyelitis (EAE), an autoimmune-mediated model of demyelination. Ferritin ablation in astrocytes reduced the severity of disease in both the acute and chronic phases. The day of onset, peak disease severity, and cumulative clinical score were all significantly reduced in ferritin KO animals. This corresponded to better performance on the rotarod and increased mobility in ferritin KO mice. Furthermore, the spinal cord of ferritin KO mice display decreased numbers of reactive astrocytes, activated microglia, and infiltrating lymphocytes. Correspondingly, the size of demyelinated lesions, iron accumulation, and oxidative stress were attenuated in the CNS of ferritin KO subjects, particularly in white matter regions of the spinal cord. Thus, deleting ferritin in astrocytes reduced neuroinflammation, oxidative stress, and myelin deterioration in EAE animals. Collectively, these findings suggest that iron storage in astrocytes is a potential therapeutic target to lessen CNS inflammation and myelin loss in autoimmune demyelinating diseases.

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

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

The role of metal ions in stroke: Current evidence and future perspectives

Metal ions play a pivotal role in maintaining optimal brain function within the human body. Nevertheless, the accumulation of these ions can result in irregularities that lead to brain damage and dysfunction. Disruptions of metal ion homeostasis can result in various pathologies, including inflammation, redox dysregulation, and blood-brain barrier disruption. While research on metal ions has chiefly focused on neurodegenerative diseases, little attention has been given to their involvement in the onset and progression of stroke. Recent studies have identified cuproptosis and confirmed ferroptosis as significant factors in stroke pathology, underscoring the importance of metal ions in stroke pathology, including abnormal ion transport, neurotoxicity, blood-brain barrier damage, and cell death. Additionally, it provides an overview of contemporary metal ion chelators and detection techniques, which may offer novel approaches to stroke treatment.

Ferroptosis in Parkinson's disease -- The iron-related degenerative disease

Parkinson's disease (PD) is a prevalent and advancing age-related neurodegenerative disorder, distinguished by the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Iron regional deposit in SNpc is a significant pathological characteristic of PD. Brain iron homeostasis is precisely regulated by iron metabolism related proteins, whereas disorder of these proteins can damage neurons and glial cells in the brain. Additionally, growing studies have reported iron metabolism related proteins are involved in the ferroptosis progression in PD. However, the effect of these proteins in the ferroptosis of PD has not been systematically summarized. This review focuses on the roles of iron metabolism related proteins in the ferroptosis of PD. Finally, we put forward the iron early diagnosis according to the observation of iron deposits in the brain and showed the recent advances in iron chelation therapy in PD.

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.

Insights into Iron Metabolism Parameters in Ischemic Stroke: A Single-Center Prospective Cohort Study

The hemojuvelin-hepcidin regulatory axis may play a key role in the iron metabolism both systemically and locally. There is a pressing need to evaluate this tightly regulated network of iron parameters and their potential impact on the development of ischemic stroke (IS). We aimed to assess iron metabolism biomarkers in patients after IS, evaluating changes over time and considering their clinical features. We studied 45 patients diagnosed with IS. We assessed major iron metabolism parameters, such as hepcidin, soluble hemojuvelin (sHJV), soluble transferrin receptor (sTfR), and ferritin, using immunoenzymathic methods at two time points: on admission and on the 7th day post IS. We found increased ferritin levels on the 7th day post IS compared to admission, and this was observed in the entire study group (p = 0.03) and in the subgroup treated with thrombolysis (p = 0.02). The hepcidin levels, on the other hand, showed a significant decrease on the 7th day, though this difference was only evident in the entire study group (p = 0.04). We also discovered significantly elevated sHJV levels in patients with PACI stroke compared to other stroke locations, both on admission and on the 7th day post IS (p < 0.05). Significantly higher sHJV levels were observed in patients treated with thrombolysis compared to those receiving conventional treatment, regardless of the time point (p < 0.0001 and p = 0.0002, respectively). Our study revealed changes in the iron metabolism parameters during stroke. The patients with anterior cerebral infarction and those treated with thrombolysis presented significantly elevated sHJV levels.

Hepcidin depending on astrocytic NEO1 ameliorates blood-brain barrier dysfunction after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) significantly compromises the blood-brain barrier (BBB) and impairs patient recovery. This study elucidates the critical role of astrocytic Neogenin-1 (NEO1) in BBB integrity post-SAH and examines the regulatory effects of hepcidin on endothelial cell (EC) function amid NEO1-mediated disruptions in iron homeostasis. Proteomic analyses of cerebrospinal fluid (CSF) from SAH patients revealed a substantial decrease in NEO1 expression, identifying it as a key factor in BBB integrity. 111 CSF proteins were significantly reduced in early SAH stages (days 1-3), with NEO1 among the most significantly altered. This dysregulation was linked to poorer patient outcomes, as indicated by a negative correlation between NEO1 levels and Modified Rankin Scale scores six months post-SAH (R = -0.4743, P < 0.0001). Experimental models further highlighted the importance of NEO1: SAH model and NEO1GFAP-Cre mice exhibited exacerbated EC dysfunction and increased BBB permeability, evidenced by significant Evans Blue retention and dextran leakage in the parietal cortex, effects that were mitigated by hepcidin administration. Our findings highlight the complex interplay between astrocytic signaling and endothelial function in SAH pathophysiology. The loss of astrocytic NEO1 led to increased EC proliferation and altered BBB structure, as confirmed by transmission electron microscopy and immunostaining for PECAM-1, indicating heightened blood vessel density in the affected cortex. Hepcidin treatment effectively reversed the EC dysfunction and BBB disruption in both NEO1-cKO mice and the SAH model, highlighting its potential as a therapeutic agent to enhance recovery and improve prognosis following SAH.

Mechanism of ferroptosis regulating ischemic stroke and pharmacologically inhibiting ferroptosis in treatment of ischemic stroke

Ferroptosis is a newly discovered form of programmed cell death that is non-caspase-dependent and is characterized by the production of lethal levels of iron-dependent lipid reactive oxygen species (ROS). In recent years, ferroptosis has attracted great interest in the field of cerebral infarction because it differs morphologically, physiologically, and genetically from other forms of cell death such as necrosis, apoptosis, autophagy, and pyroptosis. In addition, ROS is considered to be an important prognostic factor for ischemic stroke, making it a promising target for stroke treatment. This paper summarizes the induction and defense mechanisms associated with ferroptosis, and explores potential treatment strategies for ischemic stroke in order to lay the groundwork for the development of new neuroprotective drugs.

Astrocytes-Secreted WNT5B Disrupts the Blood-Brain Barrier Via ROR1/JNK/c-JUN Cascade During Meningitic Escherichia Coli Infection

The blood-brain barrier (BBB) is a complex structure that separates the central nervous system (CNS) from the peripheral blood circulation. Effective communication between different cell types within the BBB is crucial for its proper functioning and maintenance of homeostasis. In this study, we demonstrate that meningitic Escherichia coli (E. coli)-induced WNT5B plays a role in facilitating intercellular communication between astrocytes and brain microvascular endothelial cells (BMECs). We discovered that astrocytes-derived WNT5B activates the non-canonical WNT signaling pathway JNK/c-JUN in BMECs through its receptor ROR1, leading to inhibition of ZO-1 expression and impairment of the tight junction integrity in BMECs. Notably, our findings reveal that c-JUN, a transcription factor, directly regulates ZO-1 expression. By employing a dual luciferase reporting system and chromatin immunoprecipitation techniques, we identified specific binding sites of c-JUN on the ZO-1 promoter region. Overall, our study highlights the involvement of WNT5B in mediating intercellular communication between astrocytes and BMECs, provides insights into the role of WNT5B in meningitic E. coli-induced disruption of BBB integrity, and suggests potential therapeutic targeting of WNT5B as a strategy to address BBB dysfunction.

Neurotoxicity of manganese via ferroptosis induced by redox imbalance and iron overload

Manganese (Mn) is an essential trace element for maintaining bodily functions. Excessive exposure to Mn can pose serious health risks to humans and animals, particularly to the nervous system. While Mn has been implicated as a neurotoxin, the exact mechanism of its toxicity remains unclear. Ferroptosis is a form of programmed cell death that results from iron-dependent lipid peroxidation. It plays a role in various physiological and pathological cellular processes and may be closely related to Mn-induced neurotoxicity. However, the mechanism of ferroptosis in Mn-induced neurotoxicity has not been thoroughly investigated. Therefore, this study aims to investigate the role and mechanism of ferroptosis in Mn-induced neurotoxicity. Using bioinformatics, we identified significant changes in genes associated with ferroptosis in Mn-exposed animal and cellular models. We then evaluated the role of ferroptosis in Mn-induced neurotoxicity at both the animal and cellular levels. Our findings suggest that Mn exposure causes weight loss and nervous system damage in mice. In vitro and in vivo experiments have shown that exposure to Mn increases malondialdehyde, reactive oxygen species, and ferrous iron, while decreasing glutathione and adenosine triphosphate. These findings suggest that Mn exposure leads to a significant increase in lipid peroxidation and disrupts iron metabolism, resulting in oxidative stress injury and ferroptosis. Furthermore, we assessed the expression levels of proteins and mRNAs related to ferroptosis, confirming its significant involvement in Mn-induced neurotoxicity.

Cognitive impairment and hippocampal neuronal damage in β-thalassaemia mice

β-Thalassaemia is one of the most common genetic diseases worldwide. During the past few decades, life expectancy of patients has increased significantly owing to advance in medical treatments. Cognitive impairment, once has been neglected, has gradually become more documented. Cognitive impairment in β-thalassaemia patients is associated with natural history of the disease and socioeconomic factors. Herein, to determined effect of β-thalassaemia intrinsic factors, 22-month-old β-thalassaemia mouse was used as a model to assess cognitive impairment and to investigate any aberrant brain pathology in β-thalassaemia. Open field test showed that β-thalassaemia mice had decreased motor function. However, no difference of neuronal degeneration in primary motor cortex, layer 2/3 area was found. Interestingly, impaired learning and memory function accessed by a Morris water maze test was observed and correlated with a reduced number of living pyramidal neurons in hippocampus at the CA3 region in β-thalassaemia mice. Cognitive impairment in β-thalassaemia mice was significantly correlated with several intrinsic β-thalassaemic factors including iron overload, anaemia, damaged red blood cells (RBCs), phosphatidylserine (PS)-exposed RBC large extracellular vesicles (EVs) and PS-exposed medium EVs. This highlights the importance of blood transfusion and iron chelation in β-thalassaemia patients. In addition, to improve patients' quality of life, assessment of cognitive functions should become part of routine follow-up.

Iron imbalance in neurodegeneration

Iron is an essential element for the development and functionality of the brain, and anomalies in its distribution and concentration in brain tissue have been found to be associated with the most frequent neurodegenerative diseases. When magnetic resonance techniques allowed iron quantification in vivo, it was confirmed that the alteration of brain iron homeostasis is a common feature of many neurodegenerative diseases. However, whether iron is the main actor in the neurodegenerative process, or its alteration is a consequence of the degenerative process is still an open question. Because the different iron-related pathogenic mechanisms are specific for distinctive diseases, identifying the molecular mechanisms common to the various pathologies could represent a way to clarify this complex topic. Indeed, both iron overload and iron deficiency have profound consequences on cellular functioning, and both contribute to neuronal death processes in different manners, such as promoting oxidative damage, a loss of membrane integrity, a loss of proteostasis, and mitochondrial dysfunction. In this review, with the attempt to elucidate the consequences of iron dyshomeostasis for brain health, we summarize the main pathological molecular mechanisms that couple iron and neuronal death.

The Interplay between Ferroptosis and Neuroinflammation in Central Neurological Disorders

Central neurological disorders are significant contributors to morbidity, mortality, and long-term disability globally in modern society. These encompass neurodegenerative diseases, ischemic brain diseases, traumatic brain injury, epilepsy, depression, and more. The involved pathogenesis is notably intricate and diverse. Ferroptosis and neuroinflammation play pivotal roles in elucidating the causes of cognitive impairment stemming from these diseases. Given the concurrent occurrence of ferroptosis and neuroinflammation due to metabolic shifts such as iron and ROS, as well as their critical roles in central nervous disorders, the investigation into the co-regulatory mechanism of ferroptosis and neuroinflammation has emerged as a prominent area of research. This paper delves into the mechanisms of ferroptosis and neuroinflammation in central nervous disorders, along with their interrelationship. It specifically emphasizes the core molecules within the shared pathways governing ferroptosis and neuroinflammation, including SIRT1, Nrf2, NF-κB, Cox-2, iNOS/NO·, and how different immune cells and structures contribute to cognitive dysfunction through these mechanisms. Researchers' findings suggest that ferroptosis and neuroinflammation mutually promote each other and may represent key factors in the progression of central neurological disorders. A deeper comprehension of the common pathway between cellular ferroptosis and neuroinflammation holds promise for improving symptoms and prognosis related to central neurological disorders.

Iron overload suppresses hippocampal neurogenesis in adult mice: Implication for iron dysregulation-linked neurological diseases

AIMS

Adult hippocampal neurogenesis is an important player in brain homeostasis and its impairment participates in neurological diseases. Iron overload has emerged as an irreversible factor of brain aging, and is also closely related to degenerative disorders, including cognitive dysfunction. However, whether brain iron overload alters hippocampal neurogenesis has not been reported. We investigated the effect of elevated iron content on adult hippocampal neurogenesis and explored the underlying mechanism.

METHODS

Mouse models with hippocampal iron overload were generated. Neurogenesis in hippocampus and expression levels of related molecules were assessed.

RESULTS

Iron accumulation in hippocampus remarkably impaired the differentiation of neural stem cells, resulting in a significant decrease in newborn neurons. The damage was possibly attributed to iron-induced downregulation of proprotein convertase furin and subsequently decreased maturation of brain-derived neurotrophic factor (BDNF), thus contributing to memory decline and anxiety-like behavior of mice. Supportively, knockdown of furin indeed suppressed hippocampal neurogenesis, while furin overexpression restored the impairment.

CONCLUSION

These findings demonstrated that iron overload damaged hippocampal neurogenesis likely via iron-furin-BDNF pathway. This study provides new insights into potential mechanisms on iron-induced neurotoxicity and the causes of neurogenesis injury and renders modulating iron homeostasis and furin expression as novel therapeutic strategies for treatment of neurological diseases.

Cellular iron depletion enhances behavioral rhythm by limiting brain Per1 expression in mice

AIMS

Disturbances in the circadian rhythm are positively correlated with the processes of aging and related neurodegenerative diseases, which are also associated with brain iron accumulation. However, the role of brain iron in regulating the biological rhythm is poorly understood. In this study, we investigated the impact of brain iron levels on the spontaneous locomotor activity of mice with altered brain iron levels and further explored the potential mechanisms governing these effects in vitro.

RESULTS

Our results revealed that conditional knockout of ferroportin 1 (Fpn1) in cerebral microvascular endothelial cells led to brain iron deficiency, subsequently resulting in enhanced locomotor activity and increased expression of clock genes, including the circadian locomotor output cycles kaput protein (Clock) and brain and muscle ARNT-like 1 (Bmal1). Concomitantly, the levels of period circadian regulator 1 (PER1), which functions as a transcriptional repressor in regulating biological rhythm, were decreased. Conversely, the elevated brain iron levels in APP/PS1 mice inhibited autonomous rhythmic activity. Additionally, our findings demonstrate a significant decrease in serum melatonin levels in Fpn1cdh5 -CKO mice compared with the Fpn1flox/flox group. In contrast, APP/PS1 mice with brain iron deposition exhibited higher serum melatonin levels than the WT group. Furthermore, in the human glioma cell line, U251, we observed reduced PER1 expression upon iron limitation by deferoxamine (DFO; iron chelator) or endogenous overexpression of FPN1. When U251 cells were made iron-replete by supplementation with ferric ammonium citrate (FAC) or increased iron import through transferrin receptor 1 (TfR1) overexpression, PER1 protein levels were increased. Additionally, we obtained similar results to U251 cells in mouse cerebellar astrocytes (MA-c), where we collected cells at different time points to investigate the rhythmic expression of core clock genes and the impact of DFO or FAC treatment on PER1 protein levels.

CONCLUSION

These findings collectively suggest that altered iron levels influence the circadian rhythm by regulating PER1 expression and thereby modulating the molecular circadian clock. In conclusion, our study identifies the regulation of brain iron levels as a potential new target for treating age-related disruptions in the circadian rhythm.

Zonated iron deposition in the periportal zone of the liver is associated with selectively enhanced lipid synthesis

BACKGROUND AND AIMS

Disorders in liver lipid metabolism have been implicated in a range of metabolic conditions, including fatty liver and liver cancer. Altered lipid distribution within the liver, shifting from the pericentral to the periportal zone under pathological circumstances, has been observed; however, the underlying mechanism remains elusive. Iron, an essential metal, exhibits a zonal distribution in the liver similar to that of lipids. Nevertheless, the precise relationship between iron and lipid distribution, especially in the pericentral and periportal zones, remains poorly understood.

METHODS

We conducted comprehensive in vitro and in vivo experiments, combining with in situ analysis and RNA sequencing, aiming for a detailed exploration of the causal relationship between iron accumulation and lipid metabolism.

RESULTS

Our research suggests that iron overload can disrupt the normal distribution of lipids within the liver, particularly in the periportal zone. Through meticulous gene expression profiling in both the pericentral and periportal zones, we identified pyruvate carboxylase (PC) as a pivotal regulator in iron overload-induced lipid accumulation. Additionally, we revealed that the activation of cyclic adenosine monophosphate response element binding protein (CREB) was indispensable for Pc gene expression when in response to iron overload.

CONCLUSIONS

In summary, our investigation unveils the crucial involvement of iron overload in fostering hepatic lipid accumulation in the periportal zone, at least partly mediated by the modulation of Pc expression. These insights offer new perspectives for understanding the pathogenesis of fatty liver diseases and their progression.

Involvement of Astrocytes in the Formation, Maintenance, and Function of the Blood-Brain Barrier

The blood-brain barrier (BBB) is a fundamental structure that protects the composition of the brain by determining which ions, metabolites, and nutrients are allowed to enter the brain from the blood or to leave it towards the circulation. The BBB is structurally composed of a layer of brain capillary endothelial cells (BCECs) bound to each other through tight junctions (TJs). However, its development as well as maintenance and properties are controlled by the other brain cells that contact the BCECs: pericytes, glial cells, and even neurons themselves. Astrocytes seem, in particular, to have a very important role in determining and controlling most properties of the BBB. Here, we will focus on these latter cells, since the comprehension of their roles in brain physiology has been continuously expanding, even including the ability to participate in neurotransmission and in complex functions such as learning and memory. Accordingly, pathological conditions that alter astrocytic functions can alter the BBB's integrity, thus compromising many brain activities. In this review, we will also refer to different kinds of in vitro BBB models used to study the BBB's properties, evidencing its modifications under pathological conditions.

Hepcidin deficiency impairs hippocampal neurogenesis and mediates brain atrophy and memory decline in mice

BACKGROUND

Hepcidin is the master regulator of iron homeostasis. Hepcidin downregulation has been demonstrated in the brains of Alzheimer's disease (AD) patients. However, the mechanism underlying the role of hepcidin downregulation in cognitive impairment has not been elucidated.

METHODS

In the present study, we generated GFAP-Cre-mediated hepcidin conditional knockout mice (HampGFAP cKO) to explore the effect of hepcidin deficiency on hippocampal structure and neurocognition.

RESULTS

We found that the HampGFAP cKO mice developed AD-like brain atrophy and memory deficits. In particular, the weight of the hippocampus and the number of granule neurons in the dentate gyrus were significantly reduced. Further investigation demonstrated that the morphological change in the hippocampus of HampGFAP cKO mice was attributed to impaired neurogenesis caused by decreased proliferation of neural stem cells. Regarding the molecular mechanism, increased iron content after depletion of hepcidin followed by an elevated level of the inflammatory factor tumor necrosis factor-α accounted for the impairment of hippocampal neurogenesis in HampGFAP cKO mice. These observations were further verified in GFAP promoter-driven hepcidin knockdown mice and in Nestin-Cre-mediated hepcidin conditional knockout mice.

CONCLUSIONS

The present findings demonstrated a critical role for hepcidin in hippocampal neurogenesis and validated the importance of iron and associated inflammatory cytokines as key modulators of neurodevelopment, providing insights into the potential pathogenesis of cognitive dysfunction and related treatments.

Brain iron acquisition depends on age and sex in iron-deficient mice

Adequate and timely delivery of iron is essential for brain development. The uptake of transferrin-bound (Tf) iron into the brain peaks at the time of myelination, whereas the recently discovered H-ferritin (FTH1) transport of iron into the brain continues to increase beyond the peak in myelination. Here, we interrogate the impact of dietary iron deficiency (ID) on the uptake of FTH1- and Tf-bound iron. In the present study, we used C57BL/6J male and female mice at a developing (post-natal day (PND) 15) and adult age (PND 85). In developing mice, ID results in increased iron delivery from both FTH1 and Tf for both males and females. The amount of iron uptake from FTH1 was higher than the Tf and this difference between the iron delivery was much greater in females. In contrast, in the adult model, ID was associated with increased brain iron uptake by both FTH1 and Tf but only in the males. There was no increased uptake from either protein in the females. Moreover, transferrin receptor expression on the microvasculature as well as whole brain iron, and H and L ferritin levels revealed the male brains became iron deficient but not the female brains. Last, under normal dietary conditions, 55 Fe uptake was higher in the developing group from both delivery proteins than in the adult group. These results indicate that there are differences in iron acquisition between the developing and adult brain for FTH1 and Tf during nutritional ID and demonstrate a level of regulation of brain iron uptake that is age and sex-dependent.

Structural insights into ferroportin mediated iron transport

Iron is a vital trace element for almost all organisms, and maintaining iron homeostasis is critical for human health. In mammals, the only known gatekeeper between intestinally absorbed iron and circulatory blood plasma is the membrane transporter ferroportin (Fpn). As such, dysfunction of Fpn or its regulation is a key driver of iron-related pathophysiology. This review focuses on discussing recent insights from high-resolution structural studies of the Fpn protein family. While these studies have unveiled crucial details of Fpn regulation and structural architecture, the associated functional studies have also at times provided conflicting data provoking more questions than answers. Here, we summarize key findings and illuminate important remaining questions and contradictions.

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.

Function and therapeutic value of astrocytes in diabetic cognitive impairment

Diabetic cognitive impairment (DCI) is a complex complication of diabetes in the central nervous system, and its pathological mechanism is still being explored. Astrocytes are abundant glial cells in central nervous system that perform diverse functions in health and disease. Accumulating excellent research has identified astrocyte dysfunction in many neurodegenerative diseases (such as Alzheimer's disease, aging and Parkinson's disease), and summarized and discussed its pathological mechanisms and potential therapeutic value. However, the contribution of astrocytes to DCI has been largely overlooked. In this review, we first systematically summarized the effects and mechanisms of diabetes on brain astrocytes, and found that the diabetic environment (such as hyperglycemia, advanced glycation end products and cerebral insulin resistance) mediated brain reactive astrogliosis, which was specifically reflected in the changes of cell morphology and the remodeling of signature molecules. Secondly, we emphasized the contribution and potential targets of reactive astrogliosis to DCI, and found that reactive astrogliosis-induced increased blood-brain barrier permeability, glymphatic system dysfunction, neuroinflammation, abnormal cell communication and cholesterol metabolism dysregulation worsened cognitive function. In addition, we summarized effective strategies for treating DCI by targeting astrocytes. Finally, we discuss the application of new techniques in astrocytes, including single-cell transcriptome, in situ sequencing, and prospected new functions, new subsets and new targets of astrocytes in DCI.

Inflammatory responsive neutrophil-like membrane-based drug delivery system for post-surgical glioblastoma therapy

Surgical resection of glioblastoma (GBM) causes brain inflammation that activates and recruits neutrophils (NEs) to residual GBM tissues. NE-based drug delivery using inflammatory chemotaxis is promising for the post-surgical treatment of residual GBM, but its clinical application is limited by the short life span of NEs and lack of in vitro propagation methods. HL60 cells are a type of infinitely multiplying tumor cells that can be induced to differentiate into NE-like cells. We developed a novel NE-like membrane system (NM-PD) by coating NE-like membranes on the surface of poly (lactide-co-glycolide)-poly(ethylene glycol) (PLGA-PEG)-based doxorubicin (DOX)-loaded core (PLGA-PEG-DOX, PD) for post-surgical residual GBM treatment. Cell adhesion proteins were detected on NE-like membranes and endowed NM-PDs with inflammatory chemotaxis similar to mature NEs. The resulting NM-PD shows excellent inflamed in vitro blood-brain barrier (BBB) permeability and anti-proliferative effects on GBM cells. In our intracranial GBM resection model, NM-PD exhibited superior inflammatory chemotaxis and targeted residual GBM cells, thus remarkably improving antitumor capability and prolonging the survival time of the mice. These data suggest that NM-PD, which has sufficient sources and is easy to prepare, can efficiently suppress post-surgical residual GBM and holds potential for clinical transformation in GBM post-surgical adjuvant therapy.

Iron homeostasis imbalance and ferroptosis in brain diseases

Brain iron homeostasis is maintained through the normal function of blood-brain barrier and iron regulation at the systemic and cellular levels, which is fundamental to normal brain function. Excess iron can catalyze the generation of free radicals through Fenton reactions due to its dual redox state, thus causing oxidative stress. Numerous evidence has indicated brain diseases, especially stroke and neurodegenerative diseases, are closely related to the mechanism of iron homeostasis imbalance in the brain. For one thing, brain diseases promote brain iron accumulation. For another, iron accumulation amplifies damage to the nervous system and exacerbates patients' outcomes. In addition, iron accumulation triggers ferroptosis, a newly discovered iron-dependent type of programmed cell death, which is closely related to neurodegeneration and has received wide attention in recent years. In this context, we outline the mechanism of a normal brain iron metabolism and focus on the current mechanism of the iron homeostasis imbalance in stroke, Alzheimer's disease, and Parkinson's disease. Meanwhile, we also discuss the mechanism of ferroptosis and simultaneously enumerate the newly discovered drugs for iron chelators and ferroptosis inhibitors.

Ferroportin1 in the brain

Despite years of research, it remains unclear why certain brain regions of patients with neurodegenerative diseases (NDs) have abnormally high levels of iron, although it has long been suggested that disrupted expression of iron-metabolizing proteins due to genetic or non-genetic factors is responsible for the enhancement in brain iron contents. In addition to the increased expression of cell-iron importers lactoferrin (lactotransferrin) receptor (LfR) in Parkinson's disease (PD) and melanotransferrin (p97) in Alzheimer's disease (AD), some investigations have suggested that cell-iron exporter ferroportin 1 (Fpn1) may be also associated with the elevated iron observed in the brain. The decreased expression of Fpn1 and the resulting decrease in the amount of iron excreted from brain cells has been thought to be able to enhance iron levels in the brain in AD, PD and other NDs. Cumulative results also suggest that the reduction of Fpn1 can be induced by hepcidin-dependent and -independent pathways. In this article, we discuss the current understanding of Fpn1 expression in the brain and cell lines of rats, mice and humans, with emphasis on the potential involvement of reduced Fpn1 in brain iron enhancement in patients with AD, PD and other NDs.

Brain Iron Metabolism, Redox Balance and Neurological Diseases

The incidence of neurological diseases, such as Parkinson's disease, Alzheimer's disease and stroke, is increasing. An increasing number of studies have correlated these diseases with brain iron overload and the resulting oxidative damage. Brain iron deficiency has also been closely linked to neurodevelopment. These neurological disorders seriously affect the physical and mental health of patients and bring heavy economic burdens to families and society. Therefore, it is important to maintain brain iron homeostasis and to understand the mechanism of brain iron disorders affecting reactive oxygen species (ROS) balance, resulting in neural damage, cell death and, ultimately, leading to the development of disease. Evidence has shown that many therapies targeting brain iron and ROS imbalances have good preventive and therapeutic effects on neurological diseases. This review highlights the molecular mechanisms, pathogenesis and treatment strategies of brain iron metabolism disorders in neurological diseases.

Apo- and holo-transferrin differentially interact with hephaestin and ferroportin in a novel mechanism of cellular iron release regulation

BACKGROUND

Apo- (iron free) and holo- (iron bound) transferrin (Tf) participate in precise regulation of brain iron uptake at endothelial cells of the blood-brain barrier. Apo-Tf indicates an iron-deficient environment and stimulates iron release, while holo-Tf indicates an iron sufficient environment and suppresses additional iron release. Free iron is exported through ferroportin, with hephaestin as an aid to the process. Until now, the molecular mechanisms of apo- and holo-Tf influence on iron release was largely unknown.

METHODS

Here we use a variety of cell culture techniques, including co-immunoprecipitation and proximity ligation assay, in iPSC-derived endothelial cells and HEK 293 cells to investigate the mechanism by which apo- and holo-Tf influence cellular iron release. Given the established role of hepcidin in regulating cellular iron release, we further explored the relationship of hepcidin to transferrin in this model.

RESULTS

We demonstrate that holo-Tf induces the internalization of ferroportin through the established ferroportin degradation pathway. Furthermore, holo-Tf directly interacts with ferroportin, whereas apo-Tf directly interacts with hephaestin. Only pathophysiological levels of hepcidin disrupt the interaction between holo-Tf and ferroportin, but similar hepcidin levels are unable to interfere with the interaction between apo-Tf and hephaestin. The disruption of the holo-Tf and ferroportin interaction by hepcidin is due to hepcidin's ability to more rapidly internalize ferroportin compared to holo-Tf.

CONCLUSIONS

These novel findings provide a molecular mechanism for apo- and holo-Tf regulation of iron release from endothelial cells. They further demonstrate how hepcidin impacts these protein-protein interactions, and offer a model for how holo-Tf and hepcidin cooperate to suppress iron release. These results expand on our previous reports on mechanisms mediating regulation of brain iron uptake to provide a more thorough understanding of the regulatory mechanisms mediating cellular iron release in general.

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.

Huperzine A-Liposomes Efficiently Improve Neural Injury in the Hippocampus of Mice with Chronic Intermittent Hypoxia

Background

Chronic intermittent hypoxia (CIH) could cause neuronal damage, accelerating the progression of dementia. However, safe and effective therapeutic drugs and delivery are needed for successful CIH therapy.

Purpose

To investigate the neuroprotective effect of Huperzine A (HuA) packaged with nanoliposomes (HuA-LIP) on neuronal damage induced by CIH.

Methods

The stability and release of HuA-LIP in vitro were identified. Mice were randomly divided into the Control, CIH, HuA-LIP, and HuA groups. The mice in the HuA and HuA-LIP groups received HuA (0.1 mg/kg, i.p.), and HuA-LIP was administered during CIH exposure for 21 days. HuA-LIP contains the equivalent content of HuA.

Results

We prepared a novel formulation of HuA-LIP that had good stability and controlled release. First, HuA-LIP significantly ameliorated cognitive dysfunction and neuronal damage in CIH mice. Second, HuA-LIP elevated T-SOD and GSH-Px abilities and decreased MDA content to resist oxidative stress damage induced by CIH. Furthermore, HuA-LIP reduced brain iron levels by downregulating TfR1, hepcidin, and FTL expression. In addition, HuA-LIP activated the PKAα/Erk/CREB/BDNF signaling pathway and elevated MAP2, PSD95, and synaptophysin to improve synaptic plasticity. Most importantly, compared with HuA, HuA-LIP showed a superior performance against neuronal damage induced by CIH.

Conclusion

HuA-LIP has a good sustained-release effect and targeting ability and efficiently protects against neural injury caused by CIH.

Apo- and holo- transferrin differentially interact with ferroportin and hephaestin to regulate iron release at the blood-brain barrier

Background : Apo- (iron free) and holo- (iron bound) transferrin (Tf) participate in precise regulation of brain iron uptake at endothelial cells of the blood-brain barrier. Apo-Tf indicates an iron deficient environment and stimulates iron release, while holo-Tf indicates an iron sufficient environment and suppresses additional iron release. Free iron is exported through ferroportin, with hephaestin as an aid to the process. Until now, the molecular mechanism of apo- and holo-Tf's influence on iron release was largely unknown. Methods : Here we use a variety of cell culture techniques, including co-immunoprecipitation and proximity ligation assay, in iPSC-derived endothelial cells and HEK 293 cells to investigate the mechanism of apo- and holo-Tf's influence over iron release. We placed our findings in physiological context by further deciphering how hepcidin played a role in this mechanism as well. Results : We demonstrate that holo-Tf induces the internalization of ferroportin through the established ferroportin degradation pathway. Furthermore, holo-Tf directly binds to ferroportin, whereas apo-Tf directly binds to hephaestin. Only pathological levels of hepcidin disrupt the interaction between holo-Tf and ferroportin, and no amount of hepcidin disrupts the interaction between apo-Tf and hephaestin. The disruption of the holo-Tf and ferroportin interaction by hepcidin is due to hepcidin's ability to rapidly internalize ferroportin compared to holo-Tf. Conclusions : These novel findings provide a molecular mechanism for apo- and holo-Tf regulation of iron release from endothelial cells. They further demonstrate how hepcidin impacts these protein-protein interactions, and offer a model for how holo-Tf and hepcidin corporate to suppress iron release. We have established a more thorough understanding of the mechanisms behind iron release regulation with great clinical impact for a variety of neurological conditions in which iron release is dysregulated.

On the Chemical and Biological Characteristics of Multifunctional Compounds for the Treatment of Parkinson's Disease

Protein aggregation, mitochondrial dysfunction, iron dyshomeostasis, increased oxidative damage and inflammation are pathognomonic features of Parkinson's disease (PD) and other neurodegenerative disorders characterized by abnormal iron accumulation. Moreover, the existence of positive feed-back loops between these pathological components, which accelerate, and sometimes make irreversible, the neurodegenerative process, is apparent. At present, the available treatments for PD aim to relieve the symptoms, thus improving quality of life, but no treatments to stop the progression of the disease are available. Recently, the use of multifunctional compounds with the capacity to attack several of the key components of neurodegenerative processes has been proposed as a strategy to slow down the progression of neurodegenerative processes. For the treatment of PD specifically, the necessary properties of new-generation drugs should include mitochondrial destination, the center of iron-reactive oxygen species interaction, iron chelation capacity to decrease iron-mediated oxidative damage, the capacity to quench free radicals to decrease the risk of ferroptotic neuronal death, the capacity to disrupt α-synuclein aggregates and the capacity to decrease inflammatory conditions. Desirable additional characteristics are dopaminergic neurons to lessen unwanted secondary effects during long-term treatment, and the inhibition of the MAO-B and COMPT activities to increase intraneuronal dopamine content. On the basis of the published evidence, in this work, we review the molecular basis underlying the pathological events associated with PD and the clinical trials that have used single-target drugs to stop the progress of the disease. We also review the current information on multifunctional compounds that may be used for the treatment of PD and discuss the chemical characteristics that underlie their functionality. As a projection, some of these compounds or modifications could be used to treat diseases that share common pathology features with PD, such as Friedreich's ataxia, Multiple sclerosis, Huntington disease and Alzheimer's disease.

Apo- and holo- transferrin differentially interact with ferroportin and hephaestin to regulate iron release at the blood-brain barrier

Background

Apo- (iron free) and holo- (iron bound) transferrin (Tf) participate in precise regulation of brain iron uptake at endothelial cells of the blood-brain barrier. Apo-Tf indicates an iron deficient environment and stimulates iron release, while holo-Tf indicates an iron sufficient environment and suppresses additional iron release. Free iron is exported through ferroportin, with hephaestin as an aid to the process. Until now, the molecular mechanism of apo- and holo-Tf's influence on iron release was largely unknown.

Methods

Here we use a variety of cell culture techniques, including co-immunoprecipitation and proximity ligation assay, in iPSC-derived endothelial cells and HEK 293 cells to investigate the mechanism of apo- and holo-Tf's influence over iron release. We placed our findings in physiological context by further deciphering how hepcidin played a role in this mechanism as well.

Results

We demonstrate that holo-Tf induces the internalization of ferroportin through the established ferroportin degradation pathway. Furthermore, holo-Tf directly binds to ferroportin, whereas apo-Tf directly binds to hephaestin. Only pathological levels of hepcidin disrupt the interaction between holo-Tf and ferroportin, and no amount of hepcidin disrupts the interaction between apo-Tf and hephaestin. The disruption of the holo-Tf and ferroportin interaction by hepcidin is due to hepcidin's ability to rapidly internalize ferroportin compared to holo-Tf.

Conclusions

These novel findings provide a molecular mechanism for apo- and holo-Tf regulation of iron release from endothelial cells. They further demonstrate how hepcidin impacts these protein-protein interactions, and offer a model for how holo-Tf and hepcidin corporate to suppress iron release. We have established a more thorough understanding of the mechanisms behind iron release regulation with great clinical impact for a variety of neurological conditions in which iron release is dysregulated.

Detection of Ferroptosis by Immunohistochemistry and Immunofluorescence

Ferroptosis is a type of regulated cell death driven by oxidative damage, characterized by iron overload and lipid peroxidation, and regulated by a network of distinct molecules and organelles. Impaired ferroptotic response is implicated in multiple physiological and pathological processes, including tumorigenesis, neurodegeneration, and ischemia-reperfusion damage. Classical techniques of immunohistochemistry (IHC) and immunofluorescence (IF) can be employed to exhibit antigen expression and location in tissues observed with microscopy, making them powerful tools in studying the ferroptosis process. In this chapter, we introduce commonly used protocols and summarize typical markers used in IHC and IF to monitor ferroptosis.

Ferroptosis and Its Potential Role in Glioma: From Molecular Mechanisms to Therapeutic Opportunities

Glioma is the most common intracranial malignant tumor, and the current main standard treatment option is a combination of tumor surgical resection, chemotherapy and radiotherapy. Due to the terribly poor five-year survival rate of patients with gliomas and the high recurrence rate of gliomas, some new and efficient therapeutic strategies are expected. Recently, ferroptosis, as a new form of cell death, has played a significant role in the treatment of gliomas. Specifically, studies have revealed key processes of ferroptosis, including iron overload in cells, occurrence of lipid peroxidation, inactivation of cysteine/glutathione antiporter system Xc- (xCT) and glutathione peroxidase 4 (GPX4). In the present review, we summarized the molecular mechanisms of ferroptosis and introduced the application and challenges of ferroptosis in the development and treatment of gliomas. Moreover, we highlighted the therapeutic opportunities of manipulating ferroptosis to improve glioma treatments, which may improve the clinical outcome.