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Akiyama T, Kuki I, Kim K, Yamamoto N, Yamada Y, Igarashi K, Ishihara T, Hatano Y, Kobayashi K. Folic acid inhibits 5-methyltetrahydrofolate transport across the blood-cerebrospinal fluid barrier: Clinical biochemical data from two cases. JIMD Rep 2022; 63:529-535. [PMID: 36341171 PMCID: PMC9626660 DOI: 10.1002/jmd2.12321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/24/2022] [Accepted: 07/26/2022] [Indexed: 11/25/2022] Open
Abstract
Objective The use of folic acid (FA) has been discouraged in cerebral folate deficiency (CFD) because, theoretically, it could inhibit the transport of 5-methyltetrahydrofolic acid (5MTHF) across the blood-cerebrospinal fluid (CSF) barrier. We present the clinical biochemical data of two cases with CFD to support this hypothesis. Methods We measured CSF and serum 5MTHF concentrations in a patient with Kearns-Sayre syndrome (KSS) and a patient homozygous for MTHFR C677T polymorphism before and during folate supplementation therapy. To evaluate these 5MTHF concentrations, we also analyzed CSF and serum samples in pediatric patients without folate supplementation. Results Both patients had low CSF 5MTHF before treatment and high-dose FA therapy did not normalize CSF 5MTHF. There was a dissociation between serum total folate and 5MTHF concentrations during FA therapy, which was considered to be due to the appearance of unmetabolized FA. The addition of folinic acid did not improve low CSF 5MTHF in the KSS patient and the cessation of FA resulted in the normalization of CSF 5MTHF. In the patient homozygous for MTHFR C677T, minimization of the FA dosage resulted in the normalization of CSF 5MTHF and an increased CSF-to-serum 5MTHF ratio. Conclusions Our data suggest that excess supplementation of FA impaired 5MTHF transport across the blood-CSF barrier. In the treatment of CFD, supplementation of folinic acid or 5MTHF (in cases of impaired 5MTHF synthesis) is preferred over the use of FA. The reference values of CSF 5MTHF concentration based on 600 pediatric cases were also provided.
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Affiliation(s)
- Tomoyuki Akiyama
- Department of Child NeurologyOkayama University HospitalOkayamaJapan
- Department of Child Neurology, Okayama University Graduate School of MedicineDentistry and Pharmaceutical SciencesOkayamaJapan
| | - Ichiro Kuki
- Department of Pediatric NeurologyOsaka City General HospitalOsakaJapan
| | - Kiyohiro Kim
- Department of Pediatric NeurologyOsaka City General HospitalOsakaJapan
- Department of Pediatric NeurologyHyogo Prefectural Amagasaki General Medical CenterHyogoJapan
| | - Naohiro Yamamoto
- Department of Pediatric NeurologyOsaka City General HospitalOsakaJapan
| | - Yumi Yamada
- Department of NeurologyNational Hospital Organization Nishiniigata Chuo HospitalNiigataJapan
- Department of Neurology, Brain Research InstituteNiigata UniversityNiigataJapan
| | - Kazuya Igarashi
- Department of NeurologyNational Hospital Organization Nishiniigata Chuo HospitalNiigataJapan
| | - Tomohiko Ishihara
- Department of Neurology, Brain Research InstituteNiigata UniversityNiigataJapan
| | - Yuya Hatano
- Department of Neurology, Brain Research InstituteNiigata UniversityNiigataJapan
| | - Katsuhiro Kobayashi
- Department of Child NeurologyOkayama University HospitalOkayamaJapan
- Department of Child Neurology, Okayama University Graduate School of MedicineDentistry and Pharmaceutical SciencesOkayamaJapan
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2
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Alam C, Kondo M, O'Connor DL, Bendayan R. Clinical Implications of Folate Transport in the Central Nervous System. Trends Pharmacol Sci 2020; 41:349-361. [PMID: 32200980 DOI: 10.1016/j.tips.2020.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 02/19/2020] [Accepted: 02/21/2020] [Indexed: 12/11/2022]
Abstract
Folates are essential for key biosynthetic processes in mammalian cells and play a crucial role in the maintenance of central nervous system homeostasis. Mammals lack the metabolic capacity for folate biosynthesis; hence, folate requirements are largely met through dietary sources. To date, three major folate transport pathways have been characterized: the folate receptors (FRs), reduced folate carrier (RFC), and proton-coupled folate transporter (PCFT). This article reviews current knowledge on the role of folate transport systems in mediating folate delivery to vital tissues, particularly the brain, and how these pathways are modulated by various regulatory mechanisms. We will also briefly highlight the clinical significance of cerebral folate transport in relation to neurodevelopmental disorders associated with folate deficiency.
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Affiliation(s)
- Camille Alam
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Misaki Kondo
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Deborah L O'Connor
- Translational Medicine Program, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada; Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Reina Bendayan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.
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Pope S, Artuch R, Heales S, Rahman S. Cerebral folate deficiency: Analytical tests and differential diagnosis. J Inherit Metab Dis 2019; 42:655-672. [PMID: 30916789 DOI: 10.1002/jimd.12092] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/19/2019] [Accepted: 03/25/2019] [Indexed: 11/07/2022]
Abstract
Cerebral folate deficiency is typically defined as a deficiency of the major folate species 5-methyltetrahydrofolate in the cerebrospinal fluid (CSF) in the presence of normal peripheral total folate levels. However, it should be noted that cerebral folate deficiency is also often used to describe conditions where CSF 5-MTHF is low, in the presence of low or undefined peripheral folate levels. Known defects of folate transport are deficiency of the proton coupled folate transporter, associated with systemic as well as cerebral folate deficiency, and deficiency of the folate receptor alpha, leading to an isolated cerebral folate deficiency associated with intractable seizures, developmental delay and/or regression, progressive ataxia and choreoathetoid movement disorders. Inborn errors of folate metabolism include deficiencies of the enzymes methylenetetrahydrofolate reductase, dihydrofolate reductase and 5,10-methenyltetrahydrofolate synthetase. Cerebral folate deficiency is potentially a treatable condition and so prompt recognition of these inborn errors and initiation of appropriate therapy is of paramount importance. Secondary cerebral folate deficiency may be observed in other inherited metabolic diseases, including disorders of the mitochondrial oxidative phosphorylation system, serine deficiency, and pyridoxine dependent epilepsy. Other secondary causes of cerebral folate deficiency include the effects of drugs, immune response activation, toxic insults and oxidative stress. This review describes the absorption, transport and metabolism of folate within the body; analytical methods to measure folate species in blood, plasma and CSF; inherited and acquired causes of cerebral folate deficiency; and possible treatment options in those patients found to have cerebral folate deficiency.
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Affiliation(s)
- Simon Pope
- Neurometabolic Unit, National Hospital for Neurology, London, UK
| | - Rafael Artuch
- Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu and CIBERER, ISCIII, Barcelona, Spain
| | - Simon Heales
- Neurometabolic Unit, National Hospital for Neurology, London, UK
- Department of Chemical Pathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Shamima Rahman
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Metabolic Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
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Alam C, Hoque MT, Finnell RH, Goldman ID, Bendayan R. Regulation of Reduced Folate Carrier (RFC) by Vitamin D Receptor at the Blood-Brain Barrier. Mol Pharm 2017; 14:3848-3858. [PMID: 28885847 DOI: 10.1021/acs.molpharmaceut.7b00572] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Folates are essential for brain development and function. Folate transport in mammalian tissues is mediated by three major folate transport systems, i.e., reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and folate receptor alpha (FRα), known to be regulated by ligand-activated nuclear receptors, such as vitamin D receptor (VDR). Folate uptake at the choroid plexus, which requires the actions of both FRα and PCFT, is critical to cerebral folate delivery. Inactivating FRα or PCFT mutations cause severe cerebral folate deficiency resulting in early childhood neurodegeneration. The objective of this study was to investigate the role of RFC in folate uptake at the level of the blood-brain barrier (BBB) and its potential regulation by VDR. We detected robust expression of RFC in different in vitro BBB model systems, particularly in immortalized cultures of human cerebral microvascular endothelial cells (hCMEC/D3) and isolated mouse brain capillaries. [3H]-methotrexate uptake by hCMEC/D3 cells at pH 7.4 was inhibited by PT523 and pemetrexed, antifolates with high affinity for RFC. We also showed that activation of VDR through calcitriol (1,25-dihydroxyvitamin D3) exposure up-regulates RFC mRNA and protein expression as well as function in hCMEC/D3 cells and isolated mouse brain capillaries. We further demonstrated that RFC expression could be down-regulated by VDR-targeting siRNA, further confirming the role of VDR in the direct regulation of this folate transporter. Together, these data suggest that augmenting RFC functional expression could constitute a novel strategy for enhancing brain folate delivery for the treatment of neurometabolic disorders caused by loss of FRα or PCFT function.
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Affiliation(s)
- Camille Alam
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
| | - Md Tozammel Hoque
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
| | - Richard H Finnell
- Departments of Molecular and Cellular Biology and Medicine, Baylor College of Medicine , Houston, Texas 77030, United States
| | - I David Goldman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine , Bronx, New York 10461, United States
| | - Reina Bendayan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
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Batllori M, Molero-Luis M, Casado M, Sierra C, Artuch R, Ormazabal A. Biochemical Analyses of Cerebrospinal Fluid for the Diagnosis of Neurometabolic Conditions. What Can We Expect? Semin Pediatr Neurol 2016; 23:273-284. [PMID: 28284389 DOI: 10.1016/j.spen.2016.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In this article, we review the state-of-the-art analysis of different biomarkers in the cerebrospinal fluid for the diagnosis of genetically conditioned, rare, neurometabolic diseases, including glucose transport defects, neurotransmitter (dopamine, serotonin, and gamma-aminobutyric acid) and pterin deficiencies, and vitamin defects (folate, vitamin B6, and thiamine) that affect the brain. The analysis of several key metabolites are detailed, which thus highlights the preanalytical and analytical factors that should be cautiously controlled to avoid misdiagnosis; moreover, these factors may facilitate an adequate interpretation of the biochemical profiles in the context of severe neuropediatric disorders. Secondary disturbances in these biomarkers, which are associated with other genetic or environmental conditions, are also detailed. Importantly, the early biochemical identification of biochemical disturbances in the cerebrospinal fluid may improve the clinical outcomes of a remarkable number of patients, who may exhibit good neurologic outcomes using the available therapies for these disorders.
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Affiliation(s)
- Marta Batllori
- Clinical Biochemistry Department, Centre for Biomedical Research on Rare Disease (CIBERER-ISCIII), Pediatric Research Institute, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Marta Molero-Luis
- Clinical Biochemistry Department, Centre for Biomedical Research on Rare Disease (CIBERER-ISCIII), Pediatric Research Institute, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Mercedes Casado
- Clinical Biochemistry Department, Centre for Biomedical Research on Rare Disease (CIBERER-ISCIII), Pediatric Research Institute, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Cristina Sierra
- Clinical Biochemistry Department, Centre for Biomedical Research on Rare Disease (CIBERER-ISCIII), Pediatric Research Institute, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Rafael Artuch
- Clinical Biochemistry Department, Centre for Biomedical Research on Rare Disease (CIBERER-ISCIII), Pediatric Research Institute, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Aida Ormazabal
- Clinical Biochemistry Department, Centre for Biomedical Research on Rare Disease (CIBERER-ISCIII), Pediatric Research Institute, Hospital Sant Joan de Déu, Barcelona, Spain.
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Zhao R, Aluri S, Goldman ID. The proton-coupled folate transporter (PCFT-SLC46A1) and the syndrome of systemic and cerebral folate deficiency of infancy: Hereditary folate malabsorption. Mol Aspects Med 2016; 53:57-72. [PMID: 27664775 DOI: 10.1016/j.mam.2016.09.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/18/2016] [Indexed: 02/07/2023]
Abstract
The proton-coupled folate transporter (PCFT-SLC46A1) is the mechanism by which folates are absorbed across the brush-border membrane of the small intestine. The transporter is also expressed in the choroid plexus and is required for transport of folates into the cerebrospinal fluid. Loss of PCFT function, as occurs in the autosomal recessive disorder "hereditary folate malabsorption" (HFM), results in a syndrome characterized by severe systemic and cerebral folate deficiency. Folate-receptor alpha (FRα) is expressed in the choroid plexus, and loss of function of this protein, as also occurs in an autosomal recessive disorder, results solely in "cerebral folate deficiency" (CFD), the designation for this disorder. This paper reviews the current understanding of the functional and structural properties and regulation of PCFT, an electrogenic proton symporter, and contrasts PCFT properties with those of the reduced folate carrier (RFC), an organic anion antiporter, that is the major route of folate transport to systemic tissues. The clinical characteristics of HFM and its treatment, based upon the thirty-seven known cases with the clinical syndrome, of which thirty have been verified by genotype, are presented. The ways in which PCFT and FRα might interact at the level of the choroid plexus such that each is required for folate transport from blood to cerebrospinal fluid are considered along with the different clinical presentations of HFM and CFD.
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Affiliation(s)
- Rongbao Zhao
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Srinivas Aluri
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - I David Goldman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA.
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Akiyama M, Akiyama T, Kanamaru K, Kuribayashi M, Tada H, Shiokawa T, Toda S, Imai K, Kobayashi Y, Tohyama J, Sakakibara T, Yoshinaga H, Kobayashi K. Determination of CSF 5-methyltetrahydrofolate in children and its application for defects of folate transport and metabolism. Clin Chim Acta 2016; 460:120-5. [DOI: 10.1016/j.cca.2016.06.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/16/2016] [Accepted: 06/24/2016] [Indexed: 12/09/2022]
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8
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Can folic acid have a role in mitochondrial disorders? Drug Discov Today 2015; 20:1349-54. [PMID: 26183769 DOI: 10.1016/j.drudis.2015.07.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Revised: 06/16/2015] [Accepted: 07/06/2015] [Indexed: 12/17/2022]
Abstract
Cellular folate metabolism is highly compartmentalized, with mitochondria folate transport and metabolism being distinct from the well-known cytosolic folate metabolism. There is evidence supporting the association between low folate status and mitochondrial DNA (mtDNA) instability, and cerebral folate deficiency is relatively frequent in mitochondrial disorders. Furthermore, folinic acid supplementation has been reported to be beneficial not only in some patients with mitochondrial disease, but also in patients with relatively common diseases where folate deficiency might be an important pathophysiological factor. In this review, we focus on the evidence that supports the potential involvement of impaired folate metabolism in the pathophysiology of mitochondrial disorders.
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Molero-Luis M, Serrano M, O’Callaghan MM, Sierra C, Pérez-Dueñas B, García-Cazorla A, Artuch R. Clinical, etiological and therapeutic aspects of cerebral folate deficiency. Expert Rev Neurother 2015; 15:793-802. [DOI: 10.1586/14737175.2015.1055322] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Akiyama T, Tada H, Shiokawa T, Kobayashi K, Yoshinaga H. Total folate and 5-methyltetrahydrofolate in the cerebrospinal fluid of children: correlation and reference values. ACTA ACUST UNITED AC 2015; 53:2009-14. [DOI: 10.1515/cclm-2015-0208] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 03/31/2015] [Indexed: 11/15/2022]
Abstract
AbstractCerebral folate deficiency (CFD) may be underdiagnosed, as it manifests with various non-specific neurological symptoms. The diagnosis of CFD requires a determination of 5-methyltetrahydrofolate (5MTHF) in the cerebrospinal fluid (CSF), which is available in a limited number of specialized laboratories. In clinical biochemistry laboratories, total folate (TF) determination in serum or plasma is routinely performed by automated analyzers. The aim of this study is to determine whether the automated assay of CSF TF is a helpful screening tool for CFD.We analyzed CSF samples collected from 73 pediatric patients. We measured CSF TF, serum TF, and CSF 5MTHF in 73, 70, and 48 patients, respectively. The assay of 5MTHF was conducted by a newly developed system utilizing liquid chromatography-tandem mass spectrometry (LC-MS/MS). We investigated the correlation between TF and 5MTHF in the CSF.There was a strong positive correlation between CSF TF and 5MTHF (ρ=0.930, p<0.0001, n=48). Age was negatively correlated with CSF TF (ρ=−0.557, p<0.0001, n=51), serum TF (ρ=−0.457, p=0.0008, n=51), and CSF 5MTHF (ρ=−0.387, p=0.0263, n=33), but not with the CSF/serum TF ratio.The automated assay of CSF TF is helpful to estimate CSF 5MTHF. The CSF TF assay may have a significant impact on the early diagnosis of CFD, because clinicians have better access to it than the 5MTHF assay.
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