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Caverzan MD, Ibarra LE. Advancing glioblastoma treatment through iron metabolism: A focus on TfR1 and Ferroptosis innovations. Int J Biol Macromol 2024; 278:134777. [PMID: 39153669 DOI: 10.1016/j.ijbiomac.2024.134777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 08/10/2024] [Accepted: 08/13/2024] [Indexed: 08/19/2024]
Abstract
Glioblastoma (GBM) represents a formidable challenge in oncology, characterized by aggressive proliferation and poor prognosis. Iron metabolism plays a critical player in GBM progression, with dysregulated iron uptake and utilization contributing to tumor growth and therapeutic resistance. Iron's pivotal role in DNA synthesis, oxidative stress, and angiogenesis underscores its significance in GBM pathogenesis. Elevated expression of iron transporters, such as transferrin receptor 1 (TfR1), highlights the tumor's reliance on iron for survival. Innovative treatment strategies targeting iron dysregulation hold promise for overcoming therapeutic challenges in GBM management. Approaches such as iron chelation therapies, induction of ferroptosis to nanoparticle-based drug delivery systems exploit iron-dependent vulnerabilities, offering avenues for enhance treatment efficacy and improve patient outcomes. As research advances, understanding the complexities of iron-mediated carcinogenesis provides a foundation for developing precision medicine approaches tailored to combat GBM effectively. This review explores the intricate relationship between iron metabolism and GBM, elucidating its multifaceted implications and therapeutic opportunities. By consolidating the latest insights into iron metabolism in GBM, this review underscores its potential as a therapeutic target for improving patient care in combination with the standard of care approach.
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Affiliation(s)
- Matías D Caverzan
- Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Rio Cuarto (UNRC) y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Río Cuarto X5800BIA, Argentina; Departamento de Patología Animal, Facultad de Agronomía y Veterinaria, Universidad Nacional de Rio Cuarto, Rio Cuarto X5800BIA, Argentina
| | - Luis E Ibarra
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fisicoquímicas y Naturales, Universidad Nacional de Rio Cuarto, Rio Cuarto X5800BIA, Argentina; Instituto de Biotecnología Ambiental y Salud (INBIAS), Universidad Nacional de Rio Cuarto (UNRC) y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rio Cuarto X5800BIA, Argentina.
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2
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Gromadzka G, Wilkaniec A, Tarnacka B, Hadrian K, Bendykowska M, Przybyłkowski A, Litwin T. The Role of Glia in Wilson's Disease: Clinical, Neuroimaging, Neuropathological and Molecular Perspectives. Int J Mol Sci 2024; 25:7545. [PMID: 39062788 PMCID: PMC11276698 DOI: 10.3390/ijms25147545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 07/07/2024] [Accepted: 07/08/2024] [Indexed: 07/28/2024] Open
Abstract
Wilson's disease (WD) is inherited in an autosomal recessive manner and is caused by pathogenic variants of the ATP7B gene, which are responsible for impaired copper transport in the cell, inhibition of copper binding to apoceruloplasmin, and biliary excretion. This leads to the accumulation of copper in the tissues. Copper accumulation in the CNS leads to the neurological and psychiatric symptoms of WD. Abnormalities of copper metabolism in WD are associated with impaired iron metabolism. Both of these elements are redox active and may contribute to neuropathology. It has long been assumed that among parenchymal cells, astrocytes have the greatest impact on copper and iron homeostasis in the brain. Capillary endothelial cells are separated from the neuropil by astrocyte terminal legs, putting astrocytes in an ideal position to regulate the transport of iron and copper to other brain cells and protect them if metals breach the blood-brain barrier. Astrocytes are responsible for, among other things, maintaining extracellular ion homeostasis, modulating synaptic transmission and plasticity, obtaining metabolites, and protecting the brain against oxidative stress and toxins. However, excess copper and/or iron causes an increase in the number of astrocytes and their morphological changes observed in neuropathological studies, as well as a loss of the copper/iron storage function leading to macromolecule peroxidation and neuronal loss through apoptosis, autophagy, or cuproptosis/ferroptosis. The molecular mechanisms explaining the possible role of glia in copper- and iron-induced neurodegeneration in WD are largely understood from studies of neuropathology in Parkinson's disease and Alzheimer's disease. Understanding the mechanisms of glial involvement in neuroprotection/neurotoxicity is important for explaining the pathomechanisms of neuronal death in WD and, in the future, perhaps for developing more effective diagnostic/treatment methods.
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Affiliation(s)
- Grażyna Gromadzka
- Department of Biomedical Sciences, Faculty of Medicine, Collegium Medicum, Cardinal Stefan Wyszynski University, Wóycickiego 1/3, 01-938 Warsaw, Poland
| | - Anna Wilkaniec
- Department of Cellular Signalling, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego St., 02-106 Warsaw, Poland
| | - Beata Tarnacka
- Department of Rehabilitation, Medical University of Warsaw, Spartańska 1, 02-637 Warsaw, Poland
| | - Krzysztof Hadrian
- Department of Gastroenterology and Internal Medicine, Medical University of Warsaw, Banacha 1a, 02-097 Warsaw, Poland (A.P.)
| | - Maria Bendykowska
- Students Scientific Association “Immunis”, Cardinal Stefan Wyszynski University, Dewajtis 5, 01-815 Warsaw, Poland
| | - Adam Przybyłkowski
- Department of Gastroenterology and Internal Medicine, Medical University of Warsaw, Banacha 1a, 02-097 Warsaw, Poland (A.P.)
| | - Tomasz Litwin
- Second Department of Neurology, Institute of Psychiatry and Neurology, Sobieskiego 9, 02-957 Warsaw, Poland
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Marcora MS, Mattera VS, Goñi P, Aybar F, Correale JD, Pasquini JM. Iron deficiency in astrocytes alters cellular status and impacts on oligodendrocyte differentiation. J Neurosci Res 2024; 102:e25334. [PMID: 38656648 DOI: 10.1002/jnr.25334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 04/01/2024] [Accepted: 04/04/2024] [Indexed: 04/26/2024]
Abstract
Iron deficiency (ID) has been shown to affect central nervous system (CNS) development and induce hypomyelination. Previous work from our laboratory in a gestational ID model showed that both oligodendrocyte (OLG) and astrocyte (AST) maturation was impaired. To explore the contribution of AST iron to the myelination process, we generated an in vitro ID model by silencing divalent metal transporter 1 (DMT1) in AST (siDMT1 AST) or treating AST with Fe3+ chelator deferoxamine (DFX; DFX AST). siDMT1 AST showed no changes in proliferation but remained immature. Co-cultures of oligodendrocyte precursors cells (OPC) with siDMT1 AST and OPC cultures incubated with siDMT1 AST-conditioned media (ACM) rendered a reduction in OPC maturation. These findings correlated with a decrease in the expression of AST-secreted factors IGF-1, NRG-1, and LIF, known to promote OPC differentiation. siDMT1 AST also displayed increased mitochondrial number and reduced mitochondrial size as compared to control cells. DFX AST also remained immature and DFX AST-conditioned media also hampered OPC maturation in culture, in keeping with a decrease in the expression of AST-secreted growth factors IGF-1, NRG-1, LIF, and CNTF. DFX AST mitochondrial morphology and number showed results similar to those observed in siDMT1 AST. In sum, our results show that ID, induced through two different methods, impacts AST maturation and mitochondrial functioning, which in turn hampers OPC differentiation.
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Affiliation(s)
- María Silvina Marcora
- Departamento de Química Biológica e Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Vanesa Soledad Mattera
- Departamento de Química Biológica e Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Pilar Goñi
- Departamento de Química Biológica e Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Florencia Aybar
- Departamento de Química Biológica e Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Jorge Daniel Correale
- Departamento de Neurología, Fleni e Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Juana Maria Pasquini
- Departamento de Química Biológica e Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
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Xiang Y, Song X, Long D. Ferroptosis regulation through Nrf2 and implications for neurodegenerative diseases. Arch Toxicol 2024; 98:579-615. [PMID: 38265475 PMCID: PMC10861688 DOI: 10.1007/s00204-023-03660-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 12/07/2023] [Indexed: 01/25/2024]
Abstract
This article provides an overview of the background knowledge of ferroptosis in the nervous system, as well as the key role of nuclear factor E2-related factor 2 (Nrf2) in regulating ferroptosis. The article takes Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) as the starting point to explore the close association between Nrf2 and ferroptosis, which is of clear and significant importance for understanding the mechanism of neurodegenerative diseases (NDs) based on oxidative stress (OS). Accumulating evidence links ferroptosis to the pathogenesis of NDs. As the disease progresses, damage to the antioxidant system, excessive OS, and altered Nrf2 expression levels, especially the inhibition of ferroptosis by lipid peroxidation inhibitors and adaptive enhancement of Nrf2 signaling, demonstrate the potential clinical significance of Nrf2 in detecting and identifying ferroptosis, as well as targeted therapy for neuronal loss and mitochondrial dysfunction. These findings provide new insights and possibilities for the treatment and prevention of NDs.
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Affiliation(s)
- Yao Xiang
- School of Public Health, Hengyang Medical School, University of South China, Hengyang, 421001, People's Republic of China
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, Hengyang Medical School, University of South China, Hengyang, 421001, People's Republic of China
| | - Xiaohua Song
- School of Public Health, Hengyang Medical School, University of South China, Hengyang, 421001, People's Republic of China
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, Hengyang Medical School, University of South China, Hengyang, 421001, People's Republic of China
| | - Dingxin Long
- School of Public Health, Hengyang Medical School, University of South China, Hengyang, 421001, People's Republic of China.
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, Hengyang Medical School, University of South China, Hengyang, 421001, People's Republic of China.
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5
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Wang Y, Wu S, Li Q, Sun H, Wang H. Pharmacological Inhibition of Ferroptosis as a Therapeutic Target for Neurodegenerative Diseases and Strokes. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2300325. [PMID: 37341302 PMCID: PMC10460905 DOI: 10.1002/advs.202300325] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 05/23/2023] [Indexed: 06/22/2023]
Abstract
Emerging evidence suggests that ferroptosis, a unique regulated cell death modality that is morphologically and mechanistically different from other forms of cell death, plays a vital role in the pathophysiological process of neurodegenerative diseases, and strokes. Accumulating evidence supports ferroptosis as a critical factor of neurodegenerative diseases and strokes, and pharmacological inhibition of ferroptosis as a therapeutic target for these diseases. In this review article, the core mechanisms of ferroptosis are overviewed and the roles of ferroptosis in neurodegenerative diseases and strokes are described. Finally, the emerging findings in treating neurodegenerative diseases and strokes through pharmacological inhibition of ferroptosis are described. This review demonstrates that pharmacological inhibition of ferroptosis by bioactive small-molecule compounds (ferroptosis inhibitors) could be effective for treatments of these diseases, and highlights a potential promising therapeutic avenue that could be used to prevent neurodegenerative diseases and strokes. This review article will shed light on developing novel therapeutic regimens by pharmacological inhibition of ferroptosis to slow down the progression of these diseases in the future.
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Affiliation(s)
- Yumin Wang
- Department of Respiratory and Critical Care MedicineAerospace Center HospitalPeking University Aerospace School of Clinical MedicineBeijing100049P. R. China
| | - Shuang Wu
- Department of NeurologyZhongnan Hospital of Wuhan UniversityWuhan430000P. R. China
| | - Qiang Li
- Department of NeurologyThe Affiliated Hospital of Chifeng UniversityChifeng024005P. R. China
| | - Huiyan Sun
- Chifeng University Health Science CenterChifeng024000P. R. China
| | - Hongquan Wang
- Tianjin Medical University Cancer Institute and HospitalNational Clinical Research Center for CancerTianjin's Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyTianjin300060P. R. China
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Jin Y, Ren L, Jing X, Wang H. Targeting ferroptosis as novel therapeutic approaches for epilepsy. Front Pharmacol 2023; 14:1185071. [PMID: 37124220 PMCID: PMC10133701 DOI: 10.3389/fphar.2023.1185071] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 04/06/2023] [Indexed: 05/02/2023] Open
Abstract
Epilepsy is a chronic disorder of the central nervous system characterized by recurrent unprovoked seizures resulting from excessive synchronous discharge of neurons in the brain. As one of the most common complications of many neurological diseases, epilepsy is an expensive and complex global public health issue that is often accompanied by neurobehavioral comorbidities, such as abnormalities in cognition, psychiatric status, and social-adaptive behaviors. Recurrent or prolonged seizures can result in neuronal damage and cell death; however, the molecular mechanisms underlying the epilepsy-induced damage to neurons remain unclear. Ferroptosis, a novel type of regulated cell death characterized by iron-dependent lipid peroxidation, is involved in the pathophysiological progression of epilepsy. Emerging studies have demonstrated pharmacologically inhibiting ferroptosis can mitigate neuronal damage in epilepsy. In this review, we briefly describe the core molecular mechanisms of ferroptosis and the roles they play in contributing to epilepsy, highlight emerging compounds that can inhibit ferroptosis to treat epilepsy and associated neurobehavioral comorbidities, and outline their pharmacological beneficial effects. The current review suggests inhibiting ferroptosis as a therapeutic target for epilepsy and associated neurobehavioral comorbidities.
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Affiliation(s)
- Yuzi Jin
- Department of Pediatrics, Affiliated Hospital of Chengde Medical University, Chengde, Hebei, China
| | - Lei Ren
- Department of Pediatrics, Affiliated Hospital of Chengde Medical University, Chengde, Hebei, China
| | - Xiaoqing Jing
- Department of Pediatrics, Affiliated Hospital of Chengde Medical University, Chengde, Hebei, China
| | - Hongquan Wang
- Department of Pancreatic Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin’s Clinical Research Center for Cancer, Tianjin, China
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Wang F, Wang J, Shen Y, Li H, Rausch WD, Huang X. Iron Dyshomeostasis and Ferroptosis: A New Alzheimer’s Disease Hypothesis? Front Aging Neurosci 2022; 14:830569. [PMID: 35391749 PMCID: PMC8981915 DOI: 10.3389/fnagi.2022.830569] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 02/25/2022] [Indexed: 12/12/2022] Open
Abstract
Iron plays a crucial role in many physiological processes of the human body, but iron is continuously deposited in the brain as we age. Early studies found iron overload is directly proportional to cognitive decline in Alzheimer’s disease (AD). Amyloid precursor protein (APP) and tau protein, both of which are related to the AD pathogenesis, are associated with brain iron metabolism. A variety of iron metabolism-related proteins have been found to be abnormally expressed in the brains of AD patients and mouse models, resulting in iron deposition and promoting AD progression. Amyloid β (Aβ) and hyperphosphorylated tau, two pathological hallmarks of AD, can also promote iron deposition in the brain, forming a vicious cycle of AD development-iron deposition. Iron deposition and the subsequent ferroptosis has been found to be a potential mechanism underlying neuronal loss in many neurodegenerative diseases. Iron chelators, antioxidants and hepcidin were found useful for treating AD, which represents an important direction for AD treatment research and drug development in the future. The review explored the deep connection between iron dysregulation and AD pathogenesis, discussed the potential of new hypothesis related to iron dyshomeostasis and ferroptosis, and summarized the therapeutics capable of targeting iron, with the expectation to draw more attention of iron dysregulation and corresponding drug development.
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Affiliation(s)
- Feixue Wang
- Department of Traditional Chinese Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
- Beijing Geriatric Institute of Integrated Traditional and Western Medicine, Beijing, China
| | - Jiandong Wang
- Department of Traditional Chinese Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
- Beijing Geriatric Institute of Integrated Traditional and Western Medicine, Beijing, China
| | - Ying Shen
- Department of Traditional Chinese Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
- Beijing Geriatric Institute of Integrated Traditional and Western Medicine, Beijing, China
| | - Hao Li
- Department of General Diseases, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Wolf-Dieter Rausch
- Department of Biomedical Sciences, Institute of Medical Biochemistry, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Xiaobo Huang
- Department of Traditional Chinese Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
- Beijing Geriatric Institute of Integrated Traditional and Western Medicine, Beijing, China
- *Correspondence: Xiaobo Huang,
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8
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The (Bio)Chemistry of Non-Transferrin-Bound Iron. Molecules 2022; 27:molecules27061784. [PMID: 35335148 PMCID: PMC8951307 DOI: 10.3390/molecules27061784] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 12/14/2022] Open
Abstract
In healthy individuals, virtually all blood plasma iron is bound by transferrin. However, in several diseases and clinical conditions, hazardous non-transferrin-bound iron (NTBI) species occur. NTBI represents a potentially toxic iron form, being a direct cause of oxidative stress in the circulating compartment and tissue iron loading. The accumulation of these species can cause cellular damage in several organs, namely, the liver, spleen, and heart. Despite its pathophysiological relevance, the chemical nature of NTBI remains elusive. This has precluded its use as a clinical biochemical marker and the development of targeted therapies. Herein, we make a critical assessment of the current knowledge of NTBI speciation. The currently accepted hypotheses suggest that NTBI is mostly iron bound to citric acid and iron bound to serum albumin, but the chemistry of this system remains fuzzy. We explore the complex chemistry of iron complexation by citric acid and its implications towards NTBI reactivity. Further, the ability of albumin to bind iron is revised and the role of protein post-translational modifications on iron binding is discussed. The characterization of the NTBI species structure may be the starting point for the development of a standardized analytical assay, the better understanding of these species’ reactivity or the identification of NTBI uptake mechanisms by different cell types, and finally, to the development of new therapies.
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Forero-Rodríguez LJ, Josephs-Spaulding J, Flor S, Pinzón A, Kaleta C. Parkinson's Disease and the Metal-Microbiome-Gut-Brain Axis: A Systems Toxicology Approach. Antioxidants (Basel) 2021; 11:71. [PMID: 35052575 PMCID: PMC8773335 DOI: 10.3390/antiox11010071] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/02/2021] [Accepted: 12/17/2021] [Indexed: 12/14/2022] Open
Abstract
Parkinson's Disease (PD) is a neurodegenerative disease, leading to motor and non-motor complications. Autonomic alterations, including gastrointestinal symptoms, precede motor defects and act as early warning signs. Chronic exposure to dietary, environmental heavy metals impacts the gastrointestinal system and host-associated microbiome, eventually affecting the central nervous system. The correlation between dysbiosis and PD suggests a functional and bidirectional communication between the gut and the brain. The bioaccumulation of metals promotes stress mechanisms by increasing reactive oxygen species, likely altering the bidirectional gut-brain link. To better understand the differing molecular mechanisms underlying PD, integrative modeling approaches are necessary to connect multifactorial perturbations in this heterogeneous disorder. By exploring the effects of gut microbiota modulation on dietary heavy metal exposure in relation to PD onset, the modification of the host-associated microbiome to mitigate neurological stress may be a future treatment option against neurodegeneration through bioremediation. The progressive movement towards a systems toxicology framework for precision medicine can uncover molecular mechanisms underlying PD onset such as metal regulation and microbial community interactions by developing predictive models to better understand PD etiology to identify options for novel treatments and beyond. Several methodologies recently addressed the complexity of this interaction from different perspectives; however, to date, a comprehensive review of these approaches is still lacking. Therefore, our main aim through this manuscript is to fill this gap in the scientific literature by reviewing recently published papers to address the surrounding questions regarding the underlying molecular mechanisms between metals, microbiota, and the gut-brain-axis, as well as the regulation of this system to prevent neurodegeneration.
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Affiliation(s)
- Lady Johanna Forero-Rodríguez
- Research Group Bioinformatics and Systems Biology, Instituto de Genetica, Universidad Nacional de Colombia, Bogotá 111321, Colombia; (L.J.F.-R.); (A.P.)
- Research Group Medical Systems Biology, Christian-Albrechts-Universität Kiel, Brunswiker Straße 10, 24105 Kiel, Germany; (S.F.); (C.K.)
| | - Jonathan Josephs-Spaulding
- Research Group Medical Systems Biology, Christian-Albrechts-Universität Kiel, Brunswiker Straße 10, 24105 Kiel, Germany; (S.F.); (C.K.)
| | - Stefano Flor
- Research Group Medical Systems Biology, Christian-Albrechts-Universität Kiel, Brunswiker Straße 10, 24105 Kiel, Germany; (S.F.); (C.K.)
| | - Andrés Pinzón
- Research Group Bioinformatics and Systems Biology, Instituto de Genetica, Universidad Nacional de Colombia, Bogotá 111321, Colombia; (L.J.F.-R.); (A.P.)
| | - Christoph Kaleta
- Research Group Medical Systems Biology, Christian-Albrechts-Universität Kiel, Brunswiker Straße 10, 24105 Kiel, Germany; (S.F.); (C.K.)
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10
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Cheli VT, Correale J, Paez PM, Pasquini JM. Iron Metabolism in Oligodendrocytes and Astrocytes, Implications for Myelination and Remyelination. ASN Neuro 2020; 12:1759091420962681. [PMID: 32993319 PMCID: PMC7545512 DOI: 10.1177/1759091420962681] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Iron is a key nutrient for normal central nervous system (CNS) development and function; thus, iron deficiency as well as iron excess may result in harmful effects in the CNS. Oligodendrocytes and astrocytes are crucial players in brain iron equilibrium. However, the mechanisms of iron uptake, storage, and efflux in oligodendrocytes and astrocytes during CNS development or under pathological situations such as demyelination are not completely understood. In the CNS, iron is directly required for myelin production as a cofactor for enzymes involved in ATP, cholesterol and lipid synthesis, and oligodendrocytes are the cells with the highest iron levels in the brain which is linked to their elevated metabolic needs associated with the process of myelination. Unlike oligodendrocytes, astrocytes do not have a high metabolic requirement for iron. However, these cells are in close contact with blood vessel and have a strong iron transport capacity. In several pathological situations, changes in iron homoeostasis result in altered cellular iron distribution and accumulation and oxidative stress. In inflammatory demyelinating diseases such as multiple sclerosis, reactive astrocytes accumulate iron and upregulate iron efflux and influx molecules, which suggest that they are outfitted to take up and safely recycle iron. In this review, we will discuss the participation of oligodendrocytes and astrocytes in CNS iron homeostasis. Understanding the molecular mechanisms of iron uptake, storage, and efflux in oligodendrocytes and astrocytes is necessary for planning effective strategies for iron management during CNS development as well as for the treatment of demyelinating diseases.
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Affiliation(s)
- Veronica T Cheli
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, Hunter James Kelly Research Institute, The State University of New York, University at Buffalo, Buffalo, New York, United States
| | | | - Pablo M Paez
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, Hunter James Kelly Research Institute, The State University of New York, University at Buffalo, Buffalo, New York, United States
| | - Juana M Pasquini
- CONICET, Instituto de Química y Fisicoquímica Biológicas, Universidad de Buenos Aires, Buenos Aires, Argentina
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11
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Lane DD, Black KCL, Raliya R, Reed N, Kotagiri N, Gilson R, Tang R, Biswas P, Achilefu S. Effects of core titanium crystal dimension and crystal phase on ROS generation and tumour accumulation of transferrin coated titanium dioxide nanoaggregates. RSC Adv 2020; 10:23759-23766. [PMID: 32774845 PMCID: PMC7409989 DOI: 10.1039/d0ra01878c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Radionuclide-stimulated therapy (RaST), which is enhanced by Cherenkov radiation, has enabled deep tissue stimulation of UV photosensitizers, providing a new path for cancer treatment. Previous reports have shown UV-active titanium dioxide (TiO2) nanoparticles (NPs) modified with transferrin inhibit tumour growth after orthogonal treatment with Cherenkov radiation-emitting radionuclides such as 18F-fluorodeoxyglucose (FDG). However, poor understanding of TiO2 NP parameters on reactive oxygen species (ROS) generation and particle distribution limits effective therapy. Here we sought to delineate the effects of crystal phase and core TiO2 crystal dimension (cTd) on ROS production and particle morphology. We prepared Transferrin (Tf)-TiO2 nanoaggregates (NAGs) using solvothermally synthesized cTd sizes from 5 to 1000 nm diameter and holo- or apo-transferrin. Holo-transferrin was unable to stabilize TiO2 NPs while apo-transferrin stabilized TiO2 into uniform nanoaggregates (NAGs), which were invariant with differing cTd, averaging 116 ± 1.04 nm for cTds below 100 nm. ROS production increased from 5 to 25 nm cTd, attaining a peak at 25 nm before decreasing with larger sizes. The supra-25 nm ROS production decrease was partially driven by a ~1/r 3 surface area decline. Additionally, amorphous TiO2 of equal core size exhibited a 2.6-fold increase in ROS production compared to anatase NAGs, although limited stability halted further use. Although both 5 and 25 nm anatase cTds formed similarly sized NAGs, 5 nm anatase showed a four-fold higher tumour-to-muscle ratio than the 25 nm NPs in tumour-bearing mice, demonstrating the intricate relationships between physical and biological properties of NAGs. The combined in vivo and ROS results demonstrate that anatase crystals and cTd size of 25 nm or less are ideal particle parameters to balance biodistribution with ROS production efficiency.
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Affiliation(s)
- Daniel D Lane
- Optical Radiology Laboratory, Department of Radiology, Washington University in St. Louis, St. Louis, Missouri 63110, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Kvar C L Black
- Optical Radiology Laboratory, Department of Radiology, Washington University in St. Louis, St. Louis, Missouri 63110, USA
| | - Ramesh Raliya
- Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Nathan Reed
- Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Nalinikanth Kotagiri
- Optical Radiology Laboratory, Department of Radiology, Washington University in St. Louis, St. Louis, Missouri 63110, USA.,James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, Ohio 45267, USA
| | - Rebecca Gilson
- Optical Radiology Laboratory, Department of Radiology, Washington University in St. Louis, St. Louis, Missouri 63110, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Rui Tang
- Optical Radiology Laboratory, Department of Radiology, Washington University in St. Louis, St. Louis, Missouri 63110, USA
| | - Pratim Biswas
- Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Samuel Achilefu
- Optical Radiology Laboratory, Department of Radiology, Washington University in St. Louis, St. Louis, Missouri 63110, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA.,Department of Medicine, Washington University in St. Louis, St. Louis, Missouri 63110, USA.,Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St. Louis, Missouri 63110, USA
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12
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Qian ZM, Ke Y. Brain iron transport. Biol Rev Camb Philos Soc 2019; 94:1672-1684. [PMID: 31190441 DOI: 10.1111/brv.12521] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 12/19/2022]
Abstract
Brain iron is a crucial participant and regulator of normal physiological activity. However, excess iron is involved in the formation of free radicals, and has been associated with oxidative damage to neuronal and other brain cells. Abnormally high brain iron levels have been observed in various neurodegenerative diseases, including neurodegeneration with brain iron accumulation, Alzheimer's disease, Parkinson's disease and Huntington's disease. However, the key question of why iron levels increase in the relevant regions of the brain remains to be answered. A full understanding of the homeostatic mechanisms involved in brain iron transport and metabolism is therefore critical not only for elucidating the pathophysiological mechanisms responsible for excess iron accumulation in the brain but also for developing pharmacological interventions to disrupt the chain of pathological events occurring in these neurodegenerative diseases. Numerous studies have been conducted, but to date no effort to synthesize these studies and ideas into a systematic and coherent summary has been made, especially concerning iron transport across the luminal (apical) membrane of the capillary endothelium and the membranes of different brain cell types. Herein, we review key findings on brain iron transport, highlighting the mechanisms involved in iron transport across the luminal (apical) as well as the abluminal (basal) membrane of the blood-brain barrier, the blood-cerebrospinal fluid barrier, and iron uptake and release in neurons, oligodendrocytes, astrocytes and microglia within the brain. We offer suggestions for addressing the many important gaps in our understanding of this important topic, and provide new insights into the potential causes of abnormally increased iron levels in regions of the brain in neurodegenerative disorders.
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Affiliation(s)
- Zhong-Ming Qian
- Institute of Translational & Precision Medicine, Nantong University, Nantong, 226019, China.,Laboratory of Neuropharmacology, School of Pharmacy, & National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, 201203, China
| | - Ya Ke
- School of Biomedical Sciences and Gerald Choa Neuroscience Centre, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong
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13
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Haschka D, Petzer V, Kocher F, Tschurtschenthaler C, Schaefer B, Seifert M, Sopper S, Sonnweber T, Feistritzer C, Arvedson TL, Zoller H, Stauder R, Theurl I, Weiss G, Tymoszuk P. Classical and intermediate monocytes scavenge non-transferrin-bound iron and damaged erythrocytes. JCI Insight 2019; 4:98867. [PMID: 30996139 PMCID: PMC6538345 DOI: 10.1172/jci.insight.98867] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/14/2019] [Indexed: 12/12/2022] Open
Abstract
Myelomonocytic cells are critically involved in iron turnover as aged RBC recyclers. Human monocytes are divided in 3 subpopulations of classical, intermediate, and nonclassical cells, differing in inflammatory and migratory phenotype. Their functions in iron homeostasis are, however, unclear. Here, we asked whether the functional diversity of monocyte subsets translates into differences in handling physiological and pathological iron species. By microarray data analysis and flow cytometry we identified a set of iron-related genes and proteins upregulated in classical and, in part, intermediate monocytes. These included the iron exporter ferroportin (FPN1), ferritin, transferrin receptor, putative transporters of non-transferrin-bound iron (NTBI), and receptors for damaged erythrocytes. Consequently, classical monocytes displayed superior scavenging capabilities of potentially toxic NTBI, which were augmented by blocking iron export via hepcidin. The same subset and, to a lesser extent, the intermediate population, efficiently cleared damaged erythrocytes in vitro and mediated erythrophagocytosis in vivo in healthy volunteers and patients having received blood transfusions. To summarize, our data underline the physiologically important function of the classical and intermediate subset in clearing NTBI and damaged RBCs. As such, these cells may play a nonnegligible role in iron homeostasis and limit iron toxicity in iron overload conditions. Human classical and intermediate monocytes mediate clearance of non-transferrin-bound iron and erythrophagocytosis.
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Affiliation(s)
| | | | | | | | - Benedikt Schaefer
- Department of Internal Medicine I, Medical University of Innsbruck, Innsbruck, Austria
| | | | | | | | | | - Tara L Arvedson
- Department of Oncology, Amgen Inc., Thousand Oaks, California, USA
| | - Heinz Zoller
- Department of Internal Medicine I, Medical University of Innsbruck, Innsbruck, Austria
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14
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Garza-Lombó C, Posadas Y, Quintanar L, Gonsebatt ME, Franco R. Neurotoxicity Linked to Dysfunctional Metal Ion Homeostasis and Xenobiotic Metal Exposure: Redox Signaling and Oxidative Stress. Antioxid Redox Signal 2018; 28:1669-1703. [PMID: 29402131 PMCID: PMC5962337 DOI: 10.1089/ars.2017.7272] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
SIGNIFICANCE Essential metals such as copper, iron, manganese, and zinc play a role as cofactors in the activity of a wide range of processes involved in cellular homeostasis and survival, as well as during organ and tissue development. Throughout our life span, humans are also exposed to xenobiotic metals from natural and anthropogenic sources, including aluminum, arsenic, cadmium, lead, and mercury. It is well recognized that alterations in the homeostasis of essential metals and an increased environmental/occupational exposure to xenobiotic metals are linked to several neurological disorders, including neurodegeneration and neurodevelopmental alterations. Recent Advances: The redox activity of essential metals is key for neuronal homeostasis and brain function. Alterations in redox homeostasis and signaling are central to the pathological consequences of dysfunctional metal ion homeostasis and increased exposure to xenobiotic metals. Both redox-active and redox-inactive metals trigger oxidative stress and damage in the central nervous system, and the exact mechanisms involved are starting to become delineated. CRITICAL ISSUES In this review, we aim to appraise the role of essential metals in determining the redox balance in the brain and the mechanisms by which alterations in the homeostasis of essential metals and exposure to xenobiotic metals disturb the cellular redox balance and signaling. We focus on recent literature regarding their transport, metabolism, and mechanisms of toxicity in neural systems. FUTURE DIRECTIONS Delineating the specific mechanisms by which metals alter redox homeostasis is key to understand the pathological processes that convey chronic neuronal dysfunction in neurodegenerative and neurodevelopmental disorders. Antioxid. Redox Signal. 28, 1669-1703.
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Affiliation(s)
- Carla Garza-Lombó
- 1 Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln , Lincoln, Nebraska.,2 Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas , Universidad Nacional Autónoma de México, Mexico City, México
| | - Yanahi Posadas
- 3 Departamentos de Farmacología y de, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México .,4 Departamentos de Química, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México
| | - Liliana Quintanar
- 4 Departamentos de Química, Centro de Investigación y de Estudios Avanzados (CINVESTAV) , Mexico City, México
| | - María E Gonsebatt
- 2 Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas , Universidad Nacional Autónoma de México, Mexico City, México
| | - Rodrigo Franco
- 1 Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln , Lincoln, Nebraska
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15
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Xu H, Wang Y, Song N, Wang J, Jiang H, Xie J. New Progress on the Role of Glia in Iron Metabolism and Iron-Induced Degeneration of Dopamine Neurons in Parkinson's Disease. Front Mol Neurosci 2018; 10:455. [PMID: 29403352 PMCID: PMC5780449 DOI: 10.3389/fnmol.2017.00455] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 12/26/2017] [Indexed: 12/26/2022] Open
Abstract
It is now increasingly appreciated that glial cells play a critical role in the regulation of iron homeostasis. Impairment of these properties might lead to dysfunction of iron metabolism and neurodegeneration of neurons. We have previously shown that dysfunction of glia could cause iron deposit and enhance iron-induced degeneration of dopamine (DA) neurons in Parkinson’s disease (PD). There also has been a substantial growth of knowledge regarding the iron metabolism of glia and their effects on iron accumulation and degeneration of DA neurons in PD in recent years. Here, we attempt to describe the role of iron metabolism of glia and the effect of glia on iron accumulation and degeneration of DA neurons in the substantia nigra of PD. This could provide evidence to reveal the mechanisms underlying nigral iron accumulation of DA neurons in PD and provide the basis for discovering new potential therapeutic targets for PD.
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Affiliation(s)
- Huamin Xu
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
| | - Youcui Wang
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
| | - Ning Song
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
| | - Jun Wang
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
| | - Hong Jiang
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
| | - Junxia Xie
- Collaborative Innovation Center for Brain Science, Department of Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
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16
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Perfecto A, Elgy C, Valsami-Jones E, Sharp P, Hilty F, Fairweather-Tait S. Mechanisms of Iron Uptake from Ferric Phosphate Nanoparticles in Human Intestinal Caco-2 Cells. Nutrients 2017; 9:nu9040359. [PMID: 28375175 PMCID: PMC5409698 DOI: 10.3390/nu9040359] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 03/27/2017] [Accepted: 03/30/2017] [Indexed: 12/28/2022] Open
Abstract
Food fortification programs to reduce iron deficiency anemia require bioavailable forms of iron that do not cause adverse organoleptic effects. Rodent studies show that nano-sized ferric phosphate (NP-FePO4) is as bioavailable as ferrous sulfate, but there is controversy over the mechanism of absorption. We undertook in vitro studies to examine this using a Caco-2 cell model and simulated gastrointestinal (GI) digestion. Supernatant iron concentrations increased inversely with pH, and iron uptake into Caco-2 cells was 2–3 fold higher when NP-FePO4 was digested at pH 1 compared to pH 2. The size and distribution of NP-FePO4 particles during GI digestion was examined using transmission electron microscopy. The d50 of the particle distribution was 413 nm. Using disc centrifugal sedimentation, a high degree of agglomeration in NP-FePO4 following simulated GI digestion was observed, with only 20% of the particles ≤1000 nm. In Caco-2 cells, divalent metal transporter-1 (DMT1) and endocytosis inhibitors demonstrated that NP-FePO4 was mainly absorbed via DMT1. Small particles may be absorbed by clathrin-mediated endocytosis and micropinocytosis. These findings should be considered when assessing the potential of iron nanoparticles for food fortification.
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Affiliation(s)
- Antonio Perfecto
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Christine Elgy
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Eugenia Valsami-Jones
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Paul Sharp
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Florentine Hilty
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
| | - Susan Fairweather-Tait
- 1Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK; of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (C.E.); (E.V.-J.)3Diabetes and Nutritional Sciences Division, King's College London, London SE1 9NH, UK; of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland; .
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17
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Healy S, McMahon J, Owens P, FitzGerald U. Significant glial alterations in response to iron loading in a novel organotypic hippocampal slice culture model. Sci Rep 2016; 6:36410. [PMID: 27808258 PMCID: PMC5093415 DOI: 10.1038/srep36410] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 10/14/2016] [Indexed: 12/31/2022] Open
Abstract
Aberrant iron deposition in the brain is associated with neurodegenerative disorders including Multiple Sclerosis, Alzheimer’s disease and Parkinson’s disease. To study the collective response to iron loading, we have used hippocampal organotypic slices as a platform to develop a novel ex vivo model of iron accumulation. We demonstrated differential uptake and toxicity of iron after 12 h exposure to 10 μM ferrous ammonium sulphate, ferric citrate or ferrocene. Having established the supremacy of ferrocene in this model, the cultures were then loaded with 0.1–100 μM ferrocene for 12 h. One μM ferrocene exposure produced the maximal 1.6-fold increase in iron compared with vehicle. This was accompanied by a 1.4-fold increase in ferritin transcripts and mild toxicity. Using dual-immunohistochemistry, we detected ferritin in oligodendrocytes, microglia, but rarely in astrocytes and never in neurons in iron-loaded slice cultures. Moreover, iron loading led to a 15% loss of olig2-positive cells and a 16% increase in number and greater activation of microglia compared with vehicle. However, there was no appreciable effect of iron loading on astrocytes. In what we believe is a significant advance on traditional mono- or dual-cultures, our novel ex vivo slice-culture model allows characterization of the collective response of brain cells to iron-loading.
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Affiliation(s)
- Sinead Healy
- Galway Neuroscience Centre, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Jill McMahon
- Galway Neuroscience Centre, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Peter Owens
- Centre for Microscopy and Imaging, National University of Ireland, Galway, Ireland
| | - Una FitzGerald
- Galway Neuroscience Centre, School of Natural Sciences, National University of Ireland, Galway, Ireland
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18
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Choi M, Ahn S, Yang EJ, Kim H, Chong YH, Kim HS. Hippocampus-based contextual memory alters the morphological characteristics of astrocytes in the dentate gyrus. Mol Brain 2016; 9:72. [PMID: 27460927 PMCID: PMC4962445 DOI: 10.1186/s13041-016-0253-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 07/22/2016] [Indexed: 12/31/2022] Open
Abstract
Astrocytes have been reported to exist in two states, the resting and the reactive states. Morphological changes in the reactive state of astrocytes include an increase in thickness and number of processes, and an increase in the size of the cell body. Molecular changes also occur, such as an increase in the expression of glial fibrillary acidic protein (GFAP). However, the morphological and molecular changes during the process of learning and memory have not been elucidated. In the current study, we subjected Fvb/n mice to contextual fear conditioning, and checked for morphological and molecular changes in astrocytes. 1 h after fear conditioning, type II and type III astrocytes exhibited a unique status with an increased number of processes and decreased GFAP expression which differed from the typical resting or reactive state. In addition, the protein level of excitatory excitatory amino acid transporter 2 (EAAT2) was increased 1 h to 24 h after contextual fear conditioning while EAAT1 did not show any alterations. Connexin 43 (Cx43) protein was found to be increased at 24 h after fear conditioning. These data suggest that hippocampus-based contextual memory process induces changes in the status of astrocytes towards a novel status different from typical resting or reactive states. These morphological and molecular changes may be in line with functional changes.
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Affiliation(s)
- Moonseok Choi
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea
| | - Sangzin Ahn
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea
| | - Eun-Jeong Yang
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea
| | - Hyunju Kim
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea
| | - Young Hae Chong
- Department of Microbiology, School of Medicine, Ewha Womans University, 911-1, Mok-6-dong, Yangcheonku, Seoul, 158-710, Republic of Korea
| | - Hye-Sun Kim
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea. .,Seoul National University College of Medicine, Seoul National University Bundang Hospital, Sungnam, 463-707, Republic of Korea. .,Seoul National University College of Medicine, Bundang Hospital, Sungnam, Bundang-Gu, Republic of Korea. .,Neuroscience Research Institute, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, Seoul, Republic of Korea.
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19
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Li J, Zhang L, Chu Y, Namaka M, Deng B, Kong J, Bi X. Astrocytes in Oligodendrocyte Lineage Development and White Matter Pathology. Front Cell Neurosci 2016; 10:119. [PMID: 27242432 PMCID: PMC4861901 DOI: 10.3389/fncel.2016.00119] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 04/25/2016] [Indexed: 01/14/2023] Open
Abstract
White matter is primarily composed of myelin and myelinated axons. Structural and functional completeness of myelin is critical for the reliable and efficient transmission of information. White matter injury has been associated with the development of many demyelinating diseases. Despite a variety of scientific advances aimed at promoting re-myelination, their benefit has proven at best to be marginal. Research suggests that the failure of the re-myelination process may be the result of an unfavorable microenvironment. Astrocytes, are the most ample and diverse type of glial cells in central nervous system (CNS) which display multiple functions for the cells of the oligodendrocytes lineage. As such, much attention has recently been drawn to astrocyte function in terms of white matter myelin repair. They are different in white matter from those in gray matter in specific regards to development, morphology, location, protein expression and other supportive functions. During the process of demyelination and re-myelination, the functions of astrocytes are dynamic in that they are able to change functions in accordance to different time points, triggers or reactive pathways resulting in vastly different biologic effects. They have pivotal effects on oligodendrocytes and other cell types in the oligodendrocyte lineage by serving as an energy supplier, a participant of immunological and inflammatory functions, a source of trophic factors and iron and a sustainer of homeostasis. Astrocytic impairment has been shown to be directly linked to the development of neuromyelities optica (NMO). In addition, astroctyes have also been implicated in other white matter conditions such as psychiatric disorders and neurodegenerative diseases such as Alzheimer’s disease (AD), multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Inhibiting specifically detrimental signaling pathways in astrocytes while preserving their beneficial functions may be a promising approach for remyelination strategies. As such, the ability to manipulate astrocyte function represents a novel therapeutic approach that can repair the damaged myelin that is known to occur in a variety of white matter-related disorders.
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Affiliation(s)
- Jiasi Li
- Department of Neurology, Shanghai Changhai Hospital Shanghai, China
| | - Lei Zhang
- Department of Vascular Surgery, Shanghai Changhai Hospital Shanghai, China
| | - Yongxin Chu
- Department of Vascular Surgery, Affiliated Huai'an Hospital of Xuzhou Medical College Huai'an, China
| | - Michael Namaka
- Faculty of Health Sciences, College of Pharmacy and Medicine, University of Manitoba Winnipeg, MB, Canada
| | - Benqiang Deng
- Department of Neurology, Shanghai Changhai Hospital Shanghai, China
| | - Jiming Kong
- Department of Human Anatomy and Cell Science, University of Manitoba Winnipeg, MB, Canada
| | - Xiaoying Bi
- Department of Neurology, Shanghai Changhai Hospital Shanghai, China
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20
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Codazzi F, Pelizzoni I, Zacchetti D, Grohovaz F. Iron entry in neurons and astrocytes: a link with synaptic activity. Front Mol Neurosci 2015; 8:18. [PMID: 26089776 PMCID: PMC4452822 DOI: 10.3389/fnmol.2015.00018] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 05/19/2015] [Indexed: 12/14/2022] Open
Abstract
Iron plays a fundamental role in the development of the central nervous system (CNS) as well as in several neuronal functions including synaptic plasticity. Accordingly, neuronal iron supply is tightly controlled: it depends not only on transferrin-bound iron but also on non-transferrin-bound iron (NTBI), which represents a relevant quote of the iron physiologically present in the cerebrospinal fluid (CSF). Different calcium permeable channels as well as the divalent metal transporter 1 (DMT1) have been proposed to sustain NTBI entry in neurons and astrocytes even though it remains an open issue. In both cases, it emerges that the control of iron entry is tightly linked to synaptic activity. The iron-induced oxidative tone can, in physiological conditions, positively influence the calcium levels and thus the synaptic plasticity. On the other hand, an excess of iron, with the ensuing uncontrolled production of reactive oxygen species (ROS), is detrimental for neuronal survival. A protective mechanism can be played by astrocytes that, more resistant to oxidative stress, can uptake iron, thereby buffering its concentration in the synaptic environment. This competence is potentiated when astrocytes undergo activation during neuroinflammation and neurodegenerative processes. In this minireview we focus on the mechanisms responsible for NTBI entry in neurons and astrocytes and on how they can be modulated during synaptic activity. Finally, we speculate on the relevance they may have in both physiological and pathological conditions.
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Affiliation(s)
- Franca Codazzi
- Vita-Salute San Raffaele University Milan, Italy ; Division of Neuroscience, San Raffaele Scientific Institute and University Milan, Italy
| | - Ilaria Pelizzoni
- Division of Neuroscience, San Raffaele Scientific Institute and University Milan, Italy
| | - Daniele Zacchetti
- Division of Neuroscience, San Raffaele Scientific Institute and University Milan, Italy
| | - Fabio Grohovaz
- Vita-Salute San Raffaele University Milan, Italy ; Division of Neuroscience, San Raffaele Scientific Institute and University Milan, Italy
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21
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Duodenal cytochrome b (DCYTB) in iron metabolism: an update on function and regulation. Nutrients 2015; 7:2274-96. [PMID: 25835049 PMCID: PMC4425144 DOI: 10.3390/nu7042274] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 03/03/2015] [Accepted: 03/05/2015] [Indexed: 01/01/2023] Open
Abstract
Iron and ascorbate are vital cellular constituents in mammalian systems. The bulk-requirement for iron is during erythropoiesis leading to the generation of hemoglobin-containing erythrocytes. Additionally, both iron and ascorbate are required as co-factors in numerous metabolic reactions. Iron homeostasis is controlled at the level of uptake, rather than excretion. Accumulating evidence strongly suggests that in addition to the known ability of dietary ascorbate to enhance non-heme iron absorption in the gut, ascorbate regulates iron homeostasis. The involvement of ascorbate in dietary iron absorption extends beyond the direct chemical reduction of non-heme iron by dietary ascorbate. Among other activities, intra-enterocyte ascorbate appears to be involved in the provision of electrons to a family of trans-membrane redox enzymes, namely those of the cytochrome b561 class. These hemoproteins oxidize a pool of ascorbate on one side of the membrane in order to reduce an electron acceptor (e.g., non-heme iron) on the opposite side of the membrane. One member of this family, duodenal cytochrome b (DCYTB), may play an important role in ascorbate-dependent reduction of non-heme iron in the gut prior to uptake by ferrous-iron transporters. This review discusses the emerging relationship between cellular iron homeostasis, the emergent “IRP1-HIF2α axis”, DCYTB and ascorbate in relation to iron metabolism.
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22
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Ji C, Kosman DJ. Molecular mechanisms of non-transferrin-bound and transferring-bound iron uptake in primary hippocampal neurons. J Neurochem 2015; 133:668-83. [PMID: 25649872 DOI: 10.1111/jnc.13040] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 01/08/2015] [Accepted: 01/14/2015] [Indexed: 12/16/2022]
Abstract
The molecular mechanisms of iron trafficking in neurons have not been elucidated. In this study, we characterized the expression and localization of ferrous iron transporters Zip8, Zip14 and divalent metal transporter 1 (DMT1), and ferrireductases Steap2 and stromal cell-derived receptor 2 in primary rat hippocampal neurons. Steap2 and Zip8 partially co-localize, indicating these two proteins may function in Fe(3+) reduction prior to Fe(2+) permeation. Zip8, DMT1, and Steap2 co-localize with the transferrin receptor/transferrin complex, suggesting they may be involved in transferrin receptor/transferrin-mediated iron assimilation. In brain interstitial fluid, transferring-bound iron (TBI) and non-transferrin-bound iron (NTBI) exist as potential iron sources. Primary hippocampal neurons exhibit significant iron uptake from TBI (Transferrin-(59) Fe(3+)) and NTBI, whether presented as (59) Fe(2+) -citrate or (59) Fe(3+) -citrate; reductase-independent (59) Fe(2+) uptake was the most efficient uptake pathway of the three. Kinetic analysis of Zn(2+) inhibition of Fe(2+) uptake indicated that DMT1 plays only a minor role in the uptake of NTBI. In contrast, localization and knockdown data indicate that Zip8 makes a major contribution. Data suggest also that cell accumulation of (59) Fe from TBI relies at least in part on an endocytosis-independent pathway. These data suggest that Zip8 and Steap2 play a major role in iron accumulation from NTBI and TBI by hippocampal neurons. Analysis of the expression and localization of known iron uptake transporters demonstrated that Zip8 makes a major contribution to iron accumulation in primary cultures of rat embryonic hippocampal neurons. These cells exhibit uptake pathways for ferrous and ferric iron (non-transferrin-bound iron, NTBI in figure) and for transferrin-bound iron; the ferrireductases Steap2 and SDR2 support the uptake of ferric iron substrates. Zip8 and Steap2 are strongly expressed in the plasma membrane of both soma and processes, implying a crucial role in iron accumulation from NTBI and transferrin-bound iron (TBI) by hippocampal neurons.
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Affiliation(s)
- Changyi Ji
- Department of Biochemistry, State University of New York, School of Medicine and Biomedical Sciences Buffalo, Buffalo, New York, USA
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Iron transport across the blood-brain barrier: development, neurovascular regulation and cerebral amyloid angiopathy. Cell Mol Life Sci 2014; 72:709-27. [PMID: 25355056 DOI: 10.1007/s00018-014-1771-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/10/2014] [Accepted: 10/23/2014] [Indexed: 12/14/2022]
Abstract
There are two barriers for iron entry into the brain: (1) the brain-cerebrospinal fluid (CSF) barrier and (2) the blood-brain barrier (BBB). Here, we review the literature on developmental iron accumulation by the brain, focusing on the transport of iron through the brain microvascular endothelial cells (BMVEC) of the BBB. We review the iron trafficking proteins which may be involved in the iron flux across BMVEC and discuss the plausible mechanisms of BMVEC iron uptake and efflux. We suggest a model for how BMVEC iron uptake and efflux are regulated and a mechanism by which the majority of iron is trafficked across the developing BBB under the direct guidance of neighboring astrocytes. Thus, we place brain iron uptake in the context of the neurovascular unit of the adult brain. Last, we propose that BMVEC iron is involved in the aggregation of amyloid-β peptides leading to the progression of cerebral amyloid angiopathy which often occurs prior to dementia and the onset of Alzheimer's disease.
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Extracellular iron diminishes anticancer effects of vitamin C: an in vitro study. Sci Rep 2014; 4:5955. [PMID: 25092529 PMCID: PMC4121606 DOI: 10.1038/srep05955] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/16/2014] [Indexed: 12/18/2022] Open
Abstract
In vitro studies have shown that hydrogen peroxide (H2O2) produced by high-concentration ascorbate and cell culture medium iron efficiently kills cancer cells. This provided the rationale for clinical trials of high-dose intravenous ascorbate-based treatment for cancer. A drawback in all the in vitro studies was their failure to take into account the in vivo concentration of iron to supplement cell culture media which are characterized by low iron content. Here we showed, using two prostate cancer cell lines (LNCaP and PC-3) and primary astrocytes, that the anticancer/cytotoxic effects of ascorbate are completely abolished by iron at physiological concentrations in cell culture medium and human plasma. A detailed examination of mechanisms showed that iron at physiological concentrations promotes both production and decomposition of H2O2. The latter is mediated by Fenton reaction and prevents H2O2 accumulation. The hydroxyl radical, which is produced in the Fenton reaction, is buffered by extracellular proteins, and could not affect intracellular targets like H2O2. These findings show that anticancer effects of ascorbate have been significantly overestimated in previous in vitro studies, and that common cell culture media might be unsuitable for redox research.
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Oh ES, Heo C, Kim JS, Suh M, Lee YH, Kim JM. Hyperspectral fluorescence imaging for cellular iron mapping in the in vitro model of Parkinson's disease. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:051207. [PMID: 24297062 DOI: 10.1117/1.jbo.19.5.051207] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 10/28/2013] [Indexed: 06/02/2023]
Abstract
Parkinson's disease (PD) is characterized by progressive dopaminergic cell loss in the substantia nigra (SN) and elevated iron levels demonstrated by autopsy. Direct visualization of iron with live imaging techniques has not yet been successful. The aim of this study is to visualize and quantify the distribution of cellular iron using an intrinsic iron hyperspectral fluorescence signal. The 1-methyl-4-phenylpyridinium (MPP+)-induced cellular model of PD was established in SHSY5Y cells exposed to iron with ferric ammonium citrate (FAC, 100 μM). The hyperspectral fluorescence signal of iron was examined using a high-resolution dark-field optical microscope system with signal absorption for the visible/near infrared spectral range. The 6-h group showed heavy cellular iron deposition compared with the 1-h group. The cellular iron was dispersed in a small particulate form, whereas the extracellular iron was aggregated. In addition, iron particles were found to be concentrated on the cell membrane/edge of shrunken cells. The iron accumulation readily occurred in MPP+-induced cells, which is consistent with previous studies demonstrating elevated iron levels in the SN. This direct iron imaging could be applied to analyze the physiological role of iron, and its application might be expanded to various neurological disorders involving metals, such as copper, manganese, or zinc.
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Affiliation(s)
- Eung Seok Oh
- Chungnam National University Hospital, Chungnam National University School of Medicine, Department of Neurology, Daejeon, 301-721, Republic of KoreabSeoul National University Bundang Hospital, Department of Neurology, Seongnam, Kyeonggi-do, 463-707, Republic of Korea
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Pelizzoni I, Zacchetti D, Campanella A, Grohovaz F, Codazzi F. Iron uptake in quiescent and inflammation-activated astrocytes: a potentially neuroprotective control of iron burden. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1326-33. [PMID: 23583428 PMCID: PMC3787737 DOI: 10.1016/j.bbadis.2013.04.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 03/28/2013] [Accepted: 04/03/2013] [Indexed: 02/03/2023]
Abstract
Astrocytes play a crucial role in proper iron handling within the central nervous system. This competence can be fundamental, particularly during neuroinflammation, and neurodegenerative processes, where an increase in iron content can favor oxidative stress, thereby worsening disease progression. Under these pathological conditions, astrocytes undergo a process of activation that confers them either a beneficial or a detrimental role on neuronal survival. Our work investigates the mechanisms of iron entry in cultures of quiescent and activated hippocampal astrocytes. Our data confirm that the main source of iron is the non-transferrin-bound iron (NTBI) and show the involvement of two different routes for its entry: the resident transient receptor potential (TRP) channels in quiescent astrocytes and the de novo expressed divalent metal transporter 1 (DMT1) in activated astrocytes, which accounts for a potentiation of iron entry. Overall, our data suggest that at rest, but even more after activation, astrocytes have the potential to buffer the excess of iron, thereby protecting neurons from iron overload. These findings further extend our understanding of the protective role of astrocytes under the conditions of iron-mediated oxidative stress observed in several neurodegenerative conditions. Non-transferrin-bound iron (NTBI) is the main source of iron for astrocytes. TRPC channels represent an entry pathway for Fe2 + in resting astrocytes. Activation process increases the competence of astrocytes to uptake iron. DMT1 expression accounts for potentiation of iron ingress in activated astrocytes.
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Affiliation(s)
- Ilaria Pelizzoni
- San Raffaele Scientific Institute, via Olgettina 60, 20132 Milano, Italy
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Mechanistic analysis of iron accumulation by endothelial cells of the BBB. Biometals 2012; 25:665-75. [PMID: 22434419 DOI: 10.1007/s10534-012-9538-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 03/04/2012] [Indexed: 01/06/2023]
Abstract
The mechanism(s) by which iron in blood is transported across the blood-brain barrier (BBB) remains controversial. Here we have examined the first step of this trans-cellular pathway, namely the mechanism(s) of iron uptake into human brain microvascular endothelial cells (hBMVEC). We show that hBMVEC actively reduce non-transferrin bound Fe(III) (NTBI) and transferrin-bound Fe(III) (TBI); this activity is associated with one or more ferrireductases. Efficient, exo-cytoplasmic ferri-reduction from TBI is dependent upon transferrin receptor (TfR), also. Blocking holo-Tf binding with an anti-TfR antibody significantly decreases the reduction of iron from transferrin by hBMVEC, suggesting that holo-Tf needs to bind to TfR in order for efficient reduction to occur. Ferri-reduction from TBI significantly decreases when hBMVEC are pre-treated with Pt(II), an inhibitor of cell surface reductase activity. Uptake of (59)Fe from (59)Fe-Tf by endothelial cells is inhibited by 50 % when ferrozine is added to solution; in contrast, no inhibition occurs when cells are alkalinized with NH(4)Cl. This indicates that the iron reduced from holo-transferrin at the plasma membrane accounts for at least 50 % of the iron uptake observed. hBMVEC-dependent reduction and uptake of NTBI utilizes a Pt(II)-insensitive reductase. Reductase-independent uptake of Fe(II) by hBMVEC is inhibited up to 50 % by Zn(II) and/or Mn(II) by a saturable process suggesting that redundant Fe(II) transporters exist in the hBMVEC plasma membrane. These results are the first to demonstrate multiple mechanism(s) of TBI and NTBI reduction and uptake by endothelial cells (EC) of the BBB.
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