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Yamaki J, Chawla S, Tong S, Lozada KA, Yang S. Iron Effects on Clostridioides difficile Toxin Production and Antimicrobial Susceptibilities. Antibiotics (Basel) 2022; 11:537. [PMID: 35625180 PMCID: PMC9137654 DOI: 10.3390/antibiotics11050537] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 03/30/2022] [Accepted: 04/18/2022] [Indexed: 12/10/2022] Open
Abstract
Despite the benefits of red blood cell (RBC) transfusion therapy, it can render patients vulnerable to iron overload. The excess iron deposits in various body tissues cause severe complications and organ damage such as cardiotoxicity and mold infections. Clostridioides difficile infection (CDI) is the most common cause of nosocomial diarrhea among cancer patients and is associated with significant morbidity and mortality. Our study aims to determine the role of iron overload and the effects of iron chelators on CDI. Our results demonstrated that iron (Fe3+) stimulated the growth of C. difficile with increased colony formation units (CFU) in a dose-dependent manner. Exposure to excess iron also increased the gene expression levels of tcdA and tcdB. The production of C. difficile toxin A, necessary for the pathogenesis of C. difficile, was also elevated after iron treatment. In the presence of excess iron, C. difficile becomes less susceptible to metronidazole with significantly elevated minimum inhibitory concentration (MIC) but remains susceptible to vancomycin. Iron-stimulated colony formation and production of C. difficile toxins were effectively diminished by iron chelator deferoxamine co-treatment. Incorporating iron overload status as a potential factor in developing a risk prediction model of CDI and antibiotic treatment response may aid clinical practitioners in optimizing CDI management in oncology patients.
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Affiliation(s)
- Jason Yamaki
- Department of Pharmacy Practice, Chapman University School of Pharmacy, Irvine, CA 92618, USA; (J.Y.); (S.C.)
| | - Swati Chawla
- Department of Pharmacy Practice, Chapman University School of Pharmacy, Irvine, CA 92618, USA; (J.Y.); (S.C.)
| | - Shirley Tong
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA; (S.T.); (K.A.L.)
| | - Kate Alison Lozada
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA; (S.T.); (K.A.L.)
| | - Sun Yang
- Department of Pharmacy Practice, Chapman University School of Pharmacy, Irvine, CA 92618, USA; (J.Y.); (S.C.)
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Sharma S, Baral M, Kanungo BK. Recent advances in therapeutical applications of the versatile hydroxypyridinone chelators. J INCL PHENOM MACRO 2022. [DOI: 10.1007/s10847-021-01114-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Shakil MS, Parveen S, Rana Z, Walsh F, Movassaghi S, Söhnel T, Azam M, Shaheen MA, Jamieson SMF, Hanif M, Rosengren RJ, Hartinger CG. High Antiproliferative Activity of Hydroxythiopyridones over Hydroxypyridones and Their Organoruthenium Complexes. Biomedicines 2021; 9:biomedicines9020123. [PMID: 33513800 PMCID: PMC7912191 DOI: 10.3390/biomedicines9020123] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 12/12/2022] Open
Abstract
Hydroxypyr(id)ones are a pharmaceutically important class of compounds that have shown potential in diverse areas of drug discovery. We investigated the 3-hydroxy-4-pyridones 1a-1c and 3-hydroxy-4-thiopyridones 1d-1f as well as their Ru(η6-p-cymene)Cl complexes 2a-2f, and report here the molecular structures of 1b and 1d as determined by X-ray diffraction analysis. Detailed cell biological investigations revealed potent cytotoxic activity, in particular of the 3-hydroxy-4-thiopyridones 1d-1f, while the Ru complexes of both compound types were less potent, despite still showing antiproliferative activity in the low μM range. The compounds did not modulate the cell cycle distribution of cancer cells but were cytostatic in A549 and cytotoxic in NCI-H522 non-small lung cancer cells, among other effects on cancer cells.
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Affiliation(s)
- Md. Salman Shakil
- Department of Pharmacology and Toxicology, University of Otago, PO Box 56, Dunedin 9016, New Zealand; (M.S.S.); (Z.R.); (M.A.)
| | - Shahida Parveen
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; (S.P.); (F.W.); (S.M.); (T.S.)
- Department of Chemistry, University of Sargodha, Sargodha 40100, Pakistan;
| | - Zohaib Rana
- Department of Pharmacology and Toxicology, University of Otago, PO Box 56, Dunedin 9016, New Zealand; (M.S.S.); (Z.R.); (M.A.)
| | - Fearghal Walsh
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; (S.P.); (F.W.); (S.M.); (T.S.)
| | - Sanam Movassaghi
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; (S.P.); (F.W.); (S.M.); (T.S.)
| | - Tilo Söhnel
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; (S.P.); (F.W.); (S.M.); (T.S.)
| | - Mayur Azam
- Department of Pharmacology and Toxicology, University of Otago, PO Box 56, Dunedin 9016, New Zealand; (M.S.S.); (Z.R.); (M.A.)
| | | | - Stephen M. F. Jamieson
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand;
| | - Muhammad Hanif
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; (S.P.); (F.W.); (S.M.); (T.S.)
- Correspondence: (M.H.); (R.J.R.); (C.G.H.)
| | - Rhonda J. Rosengren
- Department of Pharmacology and Toxicology, University of Otago, PO Box 56, Dunedin 9016, New Zealand; (M.S.S.); (Z.R.); (M.A.)
- Correspondence: (M.H.); (R.J.R.); (C.G.H.)
| | - Christian G. Hartinger
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; (S.P.); (F.W.); (S.M.); (T.S.)
- Correspondence: (M.H.); (R.J.R.); (C.G.H.)
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Jiang X, Zhou T, Bai R, Xie Y. Hydroxypyridinone-Based Iron Chelators with Broad-Ranging Biological Activities. J Med Chem 2020; 63:14470-14501. [PMID: 33023291 DOI: 10.1021/acs.jmedchem.0c01480] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Iron plays an essential role in all living cells because of its unique chemical properties. It is also the most abundant trace element in mammals. However, when iron is present in excess or inappropriately located, it becomes toxic. Excess iron can become involved in free radical formation, resulting in oxidative stress and cellular damage. Iron chelators are used to treat serious pathological disorders associated with systemic iron overload. Hydroxypyridinones stand out for their outstanding chelation properties, including high selectivity for Fe3+ in the biological environment, ease of derivatization, and good biocompatibility. Herein, we overview the potential for multifunctional hydroxypyridinone-based chelators to be used as therapeutic agents against a wide range of diseases associated either with systemic or local elevated iron levels.
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Affiliation(s)
- Xiaoying Jiang
- Collaborative Innovation Centre of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Hangzhou, 310014, P.R. China
| | - Tao Zhou
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, P.R. China
| | - Renren Bai
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, P.R. China
| | - Yuanyuan Xie
- Collaborative Innovation Centre of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Hangzhou, 310014, P.R. China.,College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, P.R. China
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Sripetchwandee J, Khamseekaew J, Svasti S, Srichairatanakool S, Fucharoen S, Chattipakorn N, Chattipakorn SC. Deferiprone and efonidipine mitigated iron-overload induced neurotoxicity in wild-type and thalassemic mice. Life Sci 2019; 239:116878. [PMID: 31669736 DOI: 10.1016/j.lfs.2019.116878] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/10/2019] [Accepted: 09/13/2019] [Indexed: 01/23/2023]
Abstract
AIMS We previously demonstrated that iron-overload in non-thalassemic rats induced neurotoxicity and cognitive decline. However, the effect of iron-overload on the brain of thalassemic condition has never been investigated. An iron chelator (deferiprone) provides neuroprotective effects against metal toxicity. Furthermore, a T-type calcium channels blocker (efonidipine) effectively attenuates cardiac dysfunction in thalassemic mice with iron-overload. However, the effects of both drugs on brain of iron-overload thalassemia has not been determined. We hypothesize that iron-overload induces neurotoxicity in Thalassemic and wild-type mice, and not only deferiprone, but also efonidipine, provides neuroprotection against iron-overload condition. MAIN METHODS Mice from both wild-type (WT) and β-thalassemic type (HT) groups were assigned to be fed with a standard-diet or high-iron diet containing 0.2% ferrocene/kg of diet (HFe) for 4 months consecutively. After three months of HFe, 75-mg/kg/d deferiprone or 4-mg/kg/d efonidipine were administered to the HFe-fed WT and HT mice for 1 month. KEY FINDINGS HFe consumption caused an equal impact on circulating iron-overload, oxidative stress, and inflammation in WT and HT mice. Brain iron-overload and iron-mediated neurotoxicity, such as oxidative stress, inflammation, glial activation, mitochondrial dysfunction, and Alzheimer's like pathologies, were observed to an equal degree in HFe fed WT and HT mice. These pathological conditions were mitigated by both deferiprone and efonidipine. SIGNIFICANCE These findings indicate that iron-overload itself caused neurotoxicity, and T-type calcium channels may play a role in this condition.
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Affiliation(s)
- Jirapas Sripetchwandee
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Juthamas Khamseekaew
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Saovaros Svasti
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, 73170, Thailand
| | | | - Suthat Fucharoen
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - Nipon Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Siriporn C Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai, 50200, Thailand.
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6
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Gan B, Jiang X, Mi Z, Zhang C, Bai R, Shuai Q, Xie Y. Straightforward synthesis of amino-3-hydroxypyridin-4-one iron chelators via BBr 3-mediated tandem reduction of azides and deprotection of methyl ether. SYNTHETIC COMMUN 2019. [DOI: 10.1080/00397911.2018.1542002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Bing Gan
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology , Hangzhou , People’s Republic of China
| | - Xiaoying Jiang
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology , Hangzhou , People’s Republic of China
| | - Zhisheng Mi
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology , Hangzhou , People’s Republic of China
| | - Changjung Zhang
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology , Hangzhou , People’s Republic of China
| | - Renren Bai
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology , Hangzhou , People’s Republic of China
| | - Qi Shuai
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology , Hangzhou , People’s Republic of China
| | - Yuanyuan Xie
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology , Hangzhou , People’s Republic of China
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7
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The possibility of iron chelation therapy in the presence of different HPOs; a molecular approach to the non-covalent interactions and binding energies. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2018.04.065] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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8
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Khamseekaew J, Kumfu S, Palee S, Wongjaikam S, Srichairatanakool S, Fucharoen S, Chattipakorn SC, Chattipakorn N. Effects of the iron chelator deferiprone and the T-type calcium channel blocker efonidipine on cardiac function and Ca 2+ regulation in iron-overloaded thalassemic mice. Cell Calcium 2018; 72:18-25. [DOI: 10.1016/j.ceca.2018.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/29/2018] [Accepted: 01/29/2018] [Indexed: 01/07/2023]
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9
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Kumfu S, Khamseekaew J, Palee S, Srichairatanakool S, Fucharoen S, Chattipakorn SC, Chattipakorn N. Combined iron chelator and T-type calcium channel blocker exerts greater efficacy on cardioprotection than monotherapy in iron-overload thalassemic mice. Eur J Pharmacol 2018; 822:43-50. [DOI: 10.1016/j.ejphar.2018.01.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 01/04/2018] [Accepted: 01/15/2018] [Indexed: 12/15/2022]
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10
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Zandevakili T, Fatemi SJ, Sheibani V. Chelation of manganese by combining deferasirox, deferiprone and desferrioxamine in male rats as biological model. TOXIN REV 2015. [DOI: 10.3109/15569543.2015.1074924] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Golenser J, Domb A, Leshem B, Kremsner P, Luty A. Iron chelators as drugs against malaria pose a potential risk. Redox Rep 2013; 8:268-71. [PMID: 14962362 DOI: 10.1179/135100003225002880] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Affiliation(s)
- Jacob Golenser
- Department of Parasitology, The Hebrew University, Jerusalem, Israel.
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12
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Upregulation of the host SLC11A1 gene by Clostridium difficile toxin B facilitates glucosylation of Rho GTPases and enhances toxin lethality. Infect Immun 2013; 81:2724-32. [PMID: 23690404 DOI: 10.1128/iai.01177-12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Pseudomembranous enterocolitis associated with Clostridium difficile infection is an important cause of morbidity and mortality in patients being treated with antibiotics. Two closely related large protein toxins produced by C. difficile, TcdA and TcdB, which act identically but at different efficiencies to glucosylate low-molecular-weight Rho GTPases, underlie the microbe's pathogenicity. Using antisense RNA encoded by a library of human expressed sequence tags (ESTs), we randomly inactivated host chromosomal genes in HeLa cells and isolated clones that survived exposure to ordinarily lethal doses of TcdB. This phenotypic screening and subsequent analysis identified solute carrier family 11 member 1 (SLC11A1; formerly NRAMP1), a divalent cation transporter crucial to host defense against certain microbes, as an enhancer of TcdB lethality. Whereas SLC11A1 normally is poorly expressed in human cells of nonmyeloid lineage, TcdB increased SLC11A1 mRNA abundance in such cells through the actions of the RNA-binding protein HuR. We show that short hairpin RNA (shRNA) directed against SLC11A1 reduced TcdB glucosylation of small Rho GTPases and, consequently, toxin lethality. Consistent with the previously known role of SLC11A1 in cation transport, these effects were enhanced by elevation of Mn(2+) in media; conversely, they were decreased by treatment with a chelator of divalent cations. Our findings reveal an unsuspected role for SLC11A1 in determining C. difficile pathogenicity, demonstrate the novel ability of a bacterial toxin to increase its cytotoxicity, establish a mechanistic basis for these effects, and suggest a therapeutic approach to mitigate cell killing by C. difficile toxins A and B.
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Abstract
Iron overload is characterized by excessive iron deposition and consequent injury and dysfunction of the heart, liver, anterior pituitary, pancreas, and joints. Because physiologic mechanisms to excrete iron are very limited, patients with iron overload and its complications need safe, effective therapy that is compatible with their coexisting medical conditions. The availability of three licensed iron chelation drugs (one parenteral, two oral) and the development and clinical investigation of other oral chelators represent new opportunities to prevent or manage iron overload in patients with heritable types of severe anemia, such as beta-thalassemia major and sickle cell disease, and for the formulation of alternatives to phlebotomy therapy for patients with iron overload associated with the HFE gene and other adult age-of-onset types of hemochromatosis, African iron overload, and African-American iron overload.
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Affiliation(s)
- James C Barton
- Southern Iron Disorders Center, G-105, 2022 Brookwood Medical Center Drive, Birmingham, AL 35243, USA.
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Nivatpumin PJ, Gore SD. Emerging drugs for the treatment of myelodysplastic syndrome. Expert Opin Emerg Drugs 2005; 10:569-90. [PMID: 16083330 DOI: 10.1517/14728214.10.3.569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal haematopoietic stem cell disorders characterised by ineffective haematopoiesis and an increased risk of developing acute myeloid leukaemia. At present, the only curative option is allogeneic stem cell transplantation. However, the majority of patients are not eligible for this therapy, due to excessive treatment-related morbidity and mortality or lack of a suitable donor. As a result, the need for alternative therapies is great. Our improved understanding of the molecular pathogenesis of MDS has resulted in several new promising therapeutic agents. This review will consider the rational development of new agents based on the molecular biology of MDS.
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Affiliation(s)
- Philip J Nivatpumin
- Division of Hematologic Malignancies, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
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Franchini M. Recent acquisitions in the management of iron overload. Ann Hematol 2005; 84:640-5. [PMID: 16025271 DOI: 10.1007/s00277-005-1083-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 07/01/2005] [Indexed: 01/19/2023]
Abstract
Chronically transfused patients develop iron overload, which leads to organ damage and ultimately to death. The introduction of the iron-chelating agent desferrioxamine mesylate dramatically improved the life expectancy of these patients. However, the very demanding nature of this treatment (subcutaneous, continuous infusion via a battery-operated portable pump) has been the motivation for attempts to develop alternative forms of treatment that would facilitate the patients' compliance. In this review, we describe the most important advances in iron-chelation therapy.
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Affiliation(s)
- Massimo Franchini
- Servizio di Immunoematologia e Trasfusione, Azienda Ospedaliera di Verona, Piazzale L. Scuro, 10, 37134, Verona, Italy.
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Hoffbrand AV, Cohen A, Hershko C. Role of deferiprone in chelation therapy for transfusional iron overload. Blood 2003; 102:17-24. [PMID: 12637334 DOI: 10.1182/blood-2002-06-1867] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- A Victor Hoffbrand
- Department of Haematology, Royal Free Hospital, Pond Street, London NW3 2QG, United Kingdom.
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Abstract
AbstractIn the past seven years numerous genes that influence iron homeostasis have been discovered. Dr. Beutler provides a brief overview of these genes, genes that encode HFE, DMT-1, ferroportin, transferrin receptor 2, hephaestin, and hepcidin to lay the groundwork for a discussion of the various clinical forms of iron storage disease and how they differ from one another.In Section I, Dr. Beutler also discusses the types of hemochromatosis that exist as acquired and as hereditary forms. Acquired hemochromatosis occurs in patients with marrow failure, particularly when there is active ineffective erythropoiesis. Hereditary hemochromatosis is most commonly due to mutations in the HLA-linked HFE gene, and hemochromatosis clinically indistinguishable from HFE hemochromatosis is the consequence of mutations in three transferrin receptor-2 gene. A more severe, juvenile form of iron storage disease results from mutations of the gene encoding hepcidin or of a not-yet-identified gene on chromosome 1q. Autosomal dominant iron storage disease is a consequence of ferroportin mutations, and a polymorphism in the ferroportin gene appears to be involved in the African iron overload syndrome.Evidence regarding the biochemical and clinical penetrance of hemochromatosis due to mutations of the HFE gene is rapidly accumulating. These studies, emanating from several centers in Europe and the United States, all agree that the penetrance of hemochromatosis is much lower than had previously been thought. Probably only 1% of homozygotes develop clinical findings. The implications of these new findings for the management of hemochromatosis will be discussed.In Section II, Dr. Victor Hoffbrand discusses the management of iron storage disease by chelation therapy, treatment that is usually reserved for patients with secondary hemochromatosis such as occurs in the thalassemias and in patients with transfusion requirements due to myelodysplasia and other marrow failure states. Tissue iron can be estimated by determining serum ferritin levels, measuring liver iron, and by measuring cardiac iron using the MRI-T2* technique. The standard form of chelation therapy is the slow intravenous or subcutaneous infusion of desferoxamine. An orally active bidentate iron chelator, deferiprone, is now licensed in 25 countries for treatment of patients with thalassemia major. Possibly because of the ability of this compound to cross membranes, it appears to have superior cardioprotective properties. Agranulocytosis is the most serious complication of deferiprone therapy and occurs in about 1% of treated patients. Deferiprone and desferoxamine can be given together or on alternating schedules. A new orally active chelating agent ICL 670 seems promising in early clinical studies.In Section III, Dr. James Cook discusses the most common disorder of iron homeostasis, iron deficiency. He will compare some of the standard methods for identifying iron deficiency, the hemoglobin level, transferrin saturation, and mean corpuscular hemoglobin and compare these with some of the newer methods that have been introduced, specifically the percentage of hypochromic erythrocytes and reticulocyte hemoglobin content. The measurement of storage iron is achieved by measuring serum ferritin levels. The soluble transferrin receptor is a truncated form of the cellular transferrin receptor and the possible value of this measurement in the diagnosis of iron deficiency will be discussed. Until recently iron dextran was the only parental iron preparation available in the US. Sodium ferric gluconate, which has been used extensively in Europe for many years, is now available in the United States. It seems to have a distinct advantage over iron dextran in that anaphylactic reactions are much less common with the latter preparation.
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