1
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Lakhal-Littleton S, Cleland JGF. Iron deficiency and supplementation in heart failure. Nat Rev Cardiol 2024; 21:463-486. [PMID: 38326440 DOI: 10.1038/s41569-024-00988-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/08/2024] [Indexed: 02/09/2024]
Abstract
Non-anaemic iron deficiency (NAID) is a strategic target in cardiovascular medicine because of its association with a range of adverse effects in various conditions. Endeavours to tackle NAID in heart failure have yielded mixed results, exposing knowledge gaps in how best to define 'iron deficiency' and the handling of iron therapies by the body. To address these gaps, we harness the latest understanding of the mechanisms of iron homeostasis outside the erythron and integrate clinical and preclinical lines of evidence. The emerging picture is that current definitions of iron deficiency do not assimilate the multiple influences at play in patients with heart failure and, consequently, fail to identify those with a truly unmet need for iron. Additionally, current iron supplementation therapies benefit only certain patients with heart failure, reflecting differences in the nature of the unmet need for iron and the modifying effects of anaemia and inflammation on the handling of iron therapies by the body. Building on these insights, we identify untapped opportunities in the management of NAID, including the refinement of current approaches and the development of novel strategies. Lessons learned from NAID in cardiovascular disease could ultimately translate into benefits for patients with other chronic conditions such as chronic kidney disease, chronic obstructive pulmonary disease and cancer.
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Affiliation(s)
| | - John G F Cleland
- British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
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2
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Yasan GT, Gunel-Ozcan A. Hypoxia and Hypoxia Mimetic Agents As Potential Priming Approaches to Empower Mesenchymal Stem Cells. Curr Stem Cell Res Ther 2024; 19:33-54. [PMID: 36642875 DOI: 10.2174/1574888x18666230113143234] [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: 07/29/2022] [Revised: 10/12/2022] [Accepted: 11/04/2022] [Indexed: 01/17/2023]
Abstract
Mesenchymal stem cells (MSC) exhibit self-renewal capacity and multilineage differentiation potential, making them attractive for research and clinical application. The properties of MSC can vary depending on specific micro-environmental factors. MSC resides in specific niches with low oxygen concentrations, where oxygen functions as a metabolic substrate and a signaling molecule. Conventional physical incubators or chemically hypoxia mimetic agents are applied in cultures to mimic the original low oxygen tension settings where MSC originated. This review aims to focus on the current knowledge of the effects of various physical hypoxic conditions and widely used hypoxia-mimetic agents-PHD inhibitors on mesenchymal stem cells at a cellular and molecular level, including proliferation, stemness, differentiation, viability, apoptosis, senescence, migration, immunomodulation behaviors, as well as epigenetic changes.
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Affiliation(s)
| | - Aysen Gunel-Ozcan
- Department of Stem Cell Sciences, Center for Stem Cell Research and Development, Hacettepe University, Ankara, Turkey
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3
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Patrician A, Willie C, Hoiland RL, Gasho C, Subedi P, Anholm JD, Tymko MM, Ainslie PN. Manipulation of iron status on cerebral blood flow at high altitude in lowlanders and adapted highlanders. J Cereb Blood Flow Metab 2023; 43:1166-1179. [PMID: 36883428 PMCID: PMC10291452 DOI: 10.1177/0271678x231152734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/27/2023] [Accepted: 12/05/2022] [Indexed: 03/09/2023]
Abstract
Cerebral blood flow (CBF) increases during hypoxia to counteract the reduction in arterial oxygen content. The onset of tissue hypoxemia coincides with the stabilization of hypoxia-inducible factor (HIF) and transcription of downstream HIF-mediated processes. It has yet to be determined, whether HIF down- or upregulation can modulate hypoxic vasodilation of the cerebral vasculature. Therefore, we examined whether: 1) CBF would increase with iron depletion (via chelation) and decrease with repletion (via iron infusion) at high-altitude, and 2) explore whether genotypic advantages of highlanders extend to HIF-mediated regulation of CBF. In a double-blinded and block-randomized design, CBF was assessed in 82 healthy participants (38 lowlanders, 20 Sherpas and 24 Andeans), before and after the infusion of either: iron(III)-hydroxide sucrose, desferrioxamine or saline. Across both lowlanders and highlanders, baseline iron levels contributed to the variability in cerebral hypoxic reactivity at high altitude (R2 = 0.174, P < 0.001). At 5,050 m, CBF in lowlanders and Sherpa were unaltered by desferrioxamine or iron. At 4,300 m, iron infusion led to 4 ± 10% reduction in CBF (main effect of time p = 0.043) in lowlanders and Andeans. Iron status may provide a novel, albeit subtle, influence on CBF that is potentially dependent on the severity and length-of-stay at high altitude.
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Affiliation(s)
- Alexander Patrician
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia – Okanagan, Kelowna, BC, Canada
| | - Christopher Willie
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia – Okanagan, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia – Okanagan, Kelowna, BC, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher Gasho
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Prajan Subedi
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - James D Anholm
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Michael M Tymko
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia – Okanagan, Kelowna, BC, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia – Okanagan, Kelowna, BC, Canada
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4
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New Drugs and Therapies in Pulmonary Arterial Hypertension. Int J Mol Sci 2023; 24:ijms24065850. [PMID: 36982922 PMCID: PMC10058689 DOI: 10.3390/ijms24065850] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/12/2023] [Accepted: 03/14/2023] [Indexed: 03/22/2023] Open
Abstract
Pulmonary arterial hypertension is a chronic, progressive disorder of the pulmonary vasculature with associated pulmonary and cardiac remodeling. PAH was a uniformly fatal disease until the late 1970s, but with the advent of targeted therapies, the life expectancy of patients with PAH has now considerably improved. Despite these advances, PAH inevitably remains a progressive disease with significant morbidity and mortality. Thus, there is still an unmet need for the development of new drugs and other interventional therapies for the treatment of PAH. One shortcoming of currently approved vasodilator therapies is that they do not target or reverse the underlying pathogenesis of the disease process itself. A large body of evidence has evolved in the past two decades clarifying the role of genetics, dysregulation of growth factors, inflammatory pathways, mitochondrial dysfunction, DNA damage, sex hormones, neurohormonal pathways, and iron deficiency in the pathogenesis of PAH. This review focuses on newer targets and drugs that modify these pathways as well as novel interventional therapies in PAH.
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5
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Frise MC, Holdsworth DA, Johnson AW, Chung YJ, Curtis MK, Cox PJ, Clarke K, Tyler DJ, Roberts DJ, Ratcliffe PJ, Dorrington KL, Robbins PA. Abnormal whole-body energy metabolism in iron-deficient humans despite preserved skeletal muscle oxidative phosphorylation. Sci Rep 2022; 12:998. [PMID: 35046429 PMCID: PMC8770476 DOI: 10.1038/s41598-021-03968-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 12/10/2021] [Indexed: 01/01/2023] Open
Abstract
Iron deficiency impairs skeletal muscle metabolism. The underlying mechanisms are incompletely characterised, but animal and human experiments suggest the involvement of signalling pathways co-dependent upon oxygen and iron availability, including the pathway associated with hypoxia-inducible factor (HIF). We performed a prospective, case-control, clinical physiology study to explore the effects of iron deficiency on human metabolism, using exercise as a stressor. Thirteen iron-deficient (ID) individuals and thirteen iron-replete (IR) control participants each underwent 31P-magnetic resonance spectroscopy of exercising calf muscle to investigate differences in oxidative phosphorylation, followed by whole-body cardiopulmonary exercise testing. Thereafter, individuals were given an intravenous (IV) infusion, randomised to either iron or saline, and the assessments repeated ~ 1 week later. Neither baseline iron status nor IV iron significantly influenced high-energy phosphate metabolism. During submaximal cardiopulmonary exercise, the rate of decline in blood lactate concentration was diminished in the ID group (P = 0.005). Intravenous iron corrected this abnormality. Furthermore, IV iron increased lactate threshold during maximal cardiopulmonary exercise by ~ 10%, regardless of baseline iron status. These findings demonstrate abnormal whole-body energy metabolism in iron-deficient but otherwise healthy humans. Iron deficiency promotes a more glycolytic phenotype without having a detectable effect on mitochondrial bioenergetics.
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Affiliation(s)
- Matthew C Frise
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - David A Holdsworth
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Andrew W Johnson
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Yu Jin Chung
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - M Kate Curtis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Pete J Cox
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - David J Roberts
- Nuffield Department of Clinical Laboratory Sciences, National Blood Service Oxford Centre, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9BQ, UK
| | - Peter J Ratcliffe
- Nuffield Department of Medicine, University of Oxford, NDM Research Building, Old Road Campus, Headington, Oxford, OX3 7FZ, UK
- Francis Crick Institute, London, NW1 1AT, UK
| | - Keith L Dorrington
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK.
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6
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Slingo ME, Pandit JJ. Oxygen sensing, anaesthesia and critical care: a narrative review. Anaesthesia 2021; 77:213-223. [PMID: 34555179 DOI: 10.1111/anae.15582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2021] [Indexed: 12/01/2022]
Abstract
In 2019, the scientists who discovered how cells sense and adapt to oxygen availability were awarded the Nobel Prize. This elegant sensing pathway is conserved throughout evolution, and it underpins the physiology and pathology that we, as clinicians in anaesthesia and critical care, encounter on a daily basis. The purpose of this review is to bring hypoxia-inducible factor, and the oxygen-sensing pathway as a whole, to the wider clinical community. We describe how this unifying mechanism was discovered, and how it orchestrates diverse changes such as erythropoiesis, ventilatory acclimatisation, pulmonary vascular remodelling and altered metabolism. We explore the lessons learnt from genetic disorders of oxygen sensing, and the wider implications in evolution of all animal species, including our own. Finally, we explain how this pathway is relevant to our clinical practice, and how it is being manipulated in new treatments for conditions such as cancer, anaemia and pulmonary hypertension.
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Affiliation(s)
- M E Slingo
- Shackleton Department of Anaesthetics, Southampton University Hospitals NHS Trust, Southampton, UK
| | - J J Pandit
- Nuffield Department of Anaesthetics, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.,University of Oxford, Oxford, UK
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7
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Iron overload-induced oxidative stress in myelodysplastic syndromes and its cellular sequelae. Crit Rev Oncol Hematol 2021; 163:103367. [PMID: 34058341 DOI: 10.1016/j.critrevonc.2021.103367] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 03/30/2021] [Accepted: 05/03/2021] [Indexed: 12/14/2022] Open
Abstract
The myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders. MDS patients often require red blood cell transfusions, resulting in iron overload (IOL). IOL increases production of reactive oxygen species (ROS), oxygen free radicals. We review and illustrate how IOL-induced ROS influence cellular activities relevant to MDS pathophysiology. ROS damage lipids, nucleic acids in mitochondrial and nuclear DNA, structural proteins, transcription factors and enzymes. Cellular consequences include decreased metabolism and tissue and organ dysfunction. In hematopoietic stem cells (HSC), consequences of ROS include decreased glycolysis, shifting the cell from anaerobic to aerobic metabolism and causing HSC to exit the quiescent state, leading to HSC exhaustion or senescence. ROS oxidizes DNA bases, resulting in accumulation of mutations. Membrane oxidation alters fluidity and permeability. In summary, evidence indicates that IOL-induced ROS alters cellular signaling pathways resulting in toxicity to organs and hematopoietic cells, in keeping with adverse clinical outcomes in MDS.
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8
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Iron Deficiency in Pulmonary Arterial Hypertension: A Deep Dive into the Mechanisms. Cells 2021; 10:cells10020477. [PMID: 33672218 PMCID: PMC7926484 DOI: 10.3390/cells10020477] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/13/2021] [Accepted: 02/18/2021] [Indexed: 02/06/2023] Open
Abstract
Pulmonary arterial hypertension (PAH) is a severe cardiovascular disease that is caused by the progressive occlusion of the distal pulmonary arteries, eventually leading to right heart failure and death. Almost 40% of patients with PAH are iron deficient. Although widely studied, the mechanisms linking between PAH and iron deficiency remain unclear. Here we review the mechanisms regulating iron homeostasis and the preclinical and clinical data available on iron deficiency in PAH. Then we discuss the potential implications of iron deficiency on the development and management of PAH.
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9
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Willie CK, Patrician A, Hoiland RL, Williams AM, Gasho C, Subedi P, Anholm J, Drane A, Tymko MM, Nowak-Flück D, Plato S, McBride E, Varoli G, Binsted G, Eller LK, Reimer RA, MacLeod DB, Stembridge M, Ainslie PN. Influence of iron manipulation on hypoxic pulmonary vasoconstriction and pulmonary reactivity during ascent and acclimatization to 5050 m. J Physiol 2021; 599:1685-1708. [PMID: 33442904 DOI: 10.1113/jp281114] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 12/16/2020] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Iron acts as a cofactor in the stabilization of the hypoxic-inducible factor family, and plays an influential role in the modulation of hypoxic pulmonary vasoconstriction. It is uncertain whether iron regulation is altered in lowlanders during either (1) ascent to high altitude, or (2) following partial acclimatization, when compared to high-altitude adapted Sherpa. During ascent to 5050 m, the rise in pulmonary artery systolic pressure (PASP) was blunted in Sherpa, compared to lowlanders; however, upon arrival to 5050 m, PASP levels were comparable in both groups, but the reduction in iron bioavailability was more prevalent in lowlanders compared to Sherpa. Following partial acclimatization to 5050 m, there were differential influences of iron status manipulation (via iron infusion or chelation) at rest and during exercise between lowlanders and Sherpa on the pulmonary vasculature. ABSTRACT To examine the adaptational role of iron bioavailability on the pulmonary vascular responses to acute and chronic hypobaric hypoxia, the haematological and cardiopulmonary profile of lowlanders and Sherpa were determined during: (1) a 9-day ascent to 5050 m (20 lowlanders; 12 Sherpa), and (2) following partial acclimatization (11 ± 4 days) to 5050 m (18 lowlanders; 20 Sherpa), where both groups received an i.v. infusion of either iron (iron (iii)-hydroxide sucrose) or an iron chelator (desferrioxamine). During ascent, there were reductions in iron status in both lowlanders and Sherpa; however, Sherpa appeared to demonstrate a more efficient capacity to mobilize stored iron, compared to lowlanders, when expressed as a Δhepcidin per unit change in either body iron or the soluble transferrin receptor index, between 3400-5050 m (P = 0.016 and P = 0.029, respectively). The rise in pulmonary artery systolic pressure (PASP) was blunted in Sherpa, compared to lowlanders during ascent; however, PASP was comparable in both groups upon arrival to 5050 m. Following partial acclimatization, despite Sherpa demonstrating a blunted hypoxic ventilatory response and greater resting hypoxaemia, they had similar hypoxic pulmonary vasoconstriction when compared to lowlanders at rest. Iron-infusion attenuated PASP in both groups at rest (P = 0.005), while chelation did not exaggerate PASP in either group at rest or during exaggerated hypoxaemia ( P I O 2 = 67 mmHg). During exercise at 25% peak wattage, PASP was only consistently elevated in Sherpa, which persisted following both iron infusion or chelation. These findings provide new evidence on the complex interplay of iron regulation on pulmonary vascular regulation during acclimatization and adaptation to high altitude.
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Affiliation(s)
- Christopher K Willie
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Alexander Patrician
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada.,Department of Anaesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alexandra M Williams
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher Gasho
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Prajan Subedi
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - James Anholm
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Aimee Drane
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Michael M Tymko
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada.,Neurovascular Health Laboratory, University of Alberta, Edmonton, Alberta, Canada
| | - Daniela Nowak-Flück
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Sawyer Plato
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Emily McBride
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Giovanfrancesco Varoli
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Gordon Binsted
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Lindsay K Eller
- Faculty of Kinesiology and Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Raylene A Reimer
- Faculty of Kinesiology and Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - David B MacLeod
- Human Pharmacology & Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Michael Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Philip N Ainslie
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
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10
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Chung YJ, Swietach P, Curtis MK, Ball V, Robbins PA, Lakhal-Littleton S. Iron-Deficiency Anemia Results in Transcriptional and Metabolic Remodeling in the Heart Toward a Glycolytic Phenotype. Front Cardiovasc Med 2021; 7:616920. [PMID: 33553263 PMCID: PMC7859254 DOI: 10.3389/fcvm.2020.616920] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 12/01/2020] [Indexed: 12/16/2022] Open
Abstract
Iron deficiency is the most prevalent micronutrient disorder globally. When severe, iron deficiency leads to anemia, which can be deleterious to cardiac function. Given the central role of iron and oxygen in cardiac biology, multiple pathways are expected to be altered in iron-deficiency anemia, and identifying these requires an unbiased approach. To investigate these changes, gene expression and metabolism were studied in mice weaned onto an iron-deficient diet for 6 weeks. Whole-exome transcriptomics (RNAseq) identified over 1,500 differentially expressed genes (DEGs), of which 22% were upregulated and 78% were downregulated in the iron-deficient group, relative to control animals on an iron-adjusted diet. The major biological pathways affected were oxidative phosphorylation and pyruvate metabolism, as well as cardiac contraction and responses related to environmental stress. Cardiac metabolism was studied functionally using in vitro and in vivo methodologies. Spectrometric measurement of the activity of the four electron transport chain complexes in total cardiac lysates showed that the activities of Complexes I and IV were reduced in the hearts of iron-deficient animals. Pyruvate metabolism was assessed in vivo using hyperpolarized 13C magnetic resonance spectroscopy (MRS) of hyperpolarized pyruvate. Hearts from iron-deficient and anemic animals showed significantly decreased flux through pyruvate dehydrogenase and increased lactic acid production, consistent with tissue hypoxia and induction of genes coding for glycolytic enzymes and H+-monocarboxylate transport-4. Our results show that iron-deficiency anemia results in a metabolic remodeling toward a glycolytic, lactic acid-producing phenotype, a hallmark of hypoxia.
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Affiliation(s)
- Yu Jin Chung
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- The Rayne Institute, St Thomas' Hospital, London, United Kingdom
| | - Pawel Swietach
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - M. Kate Curtis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Vicky Ball
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A. Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Samira Lakhal-Littleton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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11
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Holdsworth DA, Frise MC, Bakker-Dyos J, Boos C, Dorrington KL, Woods D, Mellor A, Robbins PA. Iron bioavailability and cardiopulmonary function during ascent to very high altitude. Eur Respir J 2020; 56:13993003.02285-2019. [PMID: 32430412 PMCID: PMC7494841 DOI: 10.1183/13993003.02285-2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/17/2020] [Indexed: 11/22/2022]
Abstract
More than one hundred million people reside worldwide at altitudes in excess of 2500 m above sea level. In the millions more who sojourn at high altitude for recreational, occupational or military pursuits, hypobaric hypoxia drives physiological changes affecting the pulmonary circulation, haematocrit and right ventricle (RV) [1]. Coincident with these, maximal left ventricular (LV) stroke volume (SV) falls [2], with a reduction of 20% reported after a 2-week stay at 4300 m [3]. A rise in heart rate (HR) compensates at rest and during submaximal exercise but is insufficient during maximal intensity exercise, constraining maximal cardiac output (CO). Previously, it was considered that a reduction in plasma volume or a direct effect of hypoxia on LV myocardial contractility were probably responsible [4]. More recently it has been suggested that increased RV afterload may be of greater importance [5]. Intravenous iron supplementation at sea level is associated with enhanced stroke volume and higher SpO2 on ascent to very high altitude (5100 m). These effects appear to result from reduced pulmonary vascular resistance and improved right heart function.https://bit.ly/2VQX5fR
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Affiliation(s)
- David A Holdsworth
- Dept of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK .,Royal Centre for Defence Medicine, Queen Elizabeth Hospital, Birmingham, UK
| | - Matthew C Frise
- Dept of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Josh Bakker-Dyos
- Royal Centre for Defence Medicine, Queen Elizabeth Hospital, Birmingham, UK
| | - Christopher Boos
- Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK.,Dept of Postgraduate Medical Education, Bournemouth University, Bournemouth, UK
| | - Keith L Dorrington
- Dept of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - David Woods
- Royal Centre for Defence Medicine, Queen Elizabeth Hospital, Birmingham, UK.,Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK
| | - Adrian Mellor
- Royal Centre for Defence Medicine, Queen Elizabeth Hospital, Birmingham, UK.,Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK
| | - Peter A Robbins
- Dept of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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12
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Leitch HA, Gattermann N. Hematologic improvement with iron chelation therapy in myelodysplastic syndromes: Clinical data, potential mechanisms, and outstanding questions. Crit Rev Oncol Hematol 2019; 141:54-72. [DOI: 10.1016/j.critrevonc.2019.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 11/25/2018] [Accepted: 06/03/2019] [Indexed: 12/25/2022] Open
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13
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Affiliation(s)
- Robert C Hider
- From the Institute of Pharmaceutical Science, King's College London (R.C.H.), and the Department of Haematology, Royal Free Hospital (A.V.H.) - both in London
| | - A Victor Hoffbrand
- From the Institute of Pharmaceutical Science, King's College London (R.C.H.), and the Department of Haematology, Royal Free Hospital (A.V.H.) - both in London
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14
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Leitch HA, Buckstein R, Zhu N, Nevill TJ, Yee KWL, Leber B, Keating MM, St Hilaire E, Kumar R, Delage R, Geddes M, Storring JM, Shamy A, Elemary M, Wells RA. Iron overload in myelodysplastic syndromes: Evidence based guidelines from the Canadian consortium on MDS. Leuk Res 2018; 74:21-41. [PMID: 30286330 DOI: 10.1016/j.leukres.2018.09.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 08/08/2018] [Accepted: 09/15/2018] [Indexed: 01/19/2023]
Abstract
In 2008 the first evidence-based Canadian consensus guideline addressing the diagnosis, monitoring and management of transfusional iron overload in patients with myelodysplastic syndromes (MDS) was published. The Canadian Consortium on MDS, comprised of hematologists from across Canada with a clinical and academic interest in MDS, reconvened to update these guidelines. A literature search was updated in 2017; topics reviewed include mechanisms of iron overload induced cellular damage, evidence for clinical endpoints impacted by iron overload including organ dysfunction, infections, marrow failure, overall survival, acute myeloid leukemia progression, and endpoints around hematopoietic stem-cell transplant. Evidence for an impact of iron reduction on the same endpoints is discussed, guidelines are updated, and areas identified where evidence is suboptimal. The guidelines address common questions around the diagnosis, workup and management of iron overload in clinical practice, and take the approach of who, when, why and how to treat iron overload in MDS. Practical recommendations for treatment and monitoring are made. Evidence levels and grading of recommendations are provided for all clinical endpoints examined.
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Affiliation(s)
- Heather A Leitch
- Hematology, St. Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada.
| | - Rena Buckstein
- Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Nancy Zhu
- Hematology/Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - Thomas J Nevill
- Leukemia/BMT Program of British Columbia, Division of Hematology, Vancouver, BC, Canada
| | - Karen W L Yee
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Brian Leber
- McMaster University, Hamilton, Ontario, Canada
| | | | - Eve St Hilaire
- Centre d'Oncologie, Dr-Leon-Richard, Moncton, New Brunswick, Canada
| | - Rajat Kumar
- Hematology/Oncology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Robert Delage
- Hematology Department, Centre Hospitalier Universitaire, Laval University, Quebec, QC, Canada
| | - Michelle Geddes
- Department of Medicine/Hematology, Foothills Medical Centre, Calgary, Alberta, Canada
| | | | - April Shamy
- Sir Mortimer B Davis Hospital, McGill University, Montreal, Quebec, Canada
| | - Mohamed Elemary
- Saskatoon Cancer Center, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Richard A Wells
- Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
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Parvu AV, Bojan A, Urian L, Torok T, Zsoldos IA, Iancu M. Ferritin level changes and erythroid improvement in a group of adult polytransfused patients treated with Deferasirox. ACTA ACUST UNITED AC 2018; 91:288-292. [PMID: 30093806 PMCID: PMC6082613 DOI: 10.15386/cjmed-942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 12/05/2017] [Indexed: 11/23/2022]
Abstract
Background and aims Chelating agents therapy is recommended for polytransfused patients that have evidence of iron overload (an elevated serum ferritin or received over 20 units of red blood cell transfusions). Deferasirox showed efficacy and safety in maintaining or reducing body iron. Iron chelation therapy was associated with hematopoiesis improvement in transfusion-dependent patients.Our objectives were to analyze differences in ferritin level in adult polytransfused patients treated with Deferasirox, to estimate the erythroid improvement and variation of the number of red blood cell transfusion after introducing Deferasirox, to evaluate the side effects of the treatment. Methods Retrospective study including all the adult polytransfused patients treated with Deferasirox in Hematology Departments of three county hospitals in the North-West of Romania. Results We included 40 polytransfused patients treated with Deferasirox in standard doses. There was a significant reduction in serum ferritine from baseline for all the patients (Friedman test, χ2(2)=26.82, p<0.001). Safety profile of Deferasirox was good (three digestive side effects). RBCT were administered before (mean 2.43±1.09 units/month) and after starting Deferasirox (mean 1.40±0.97 units/month), the difference is statistically significant (Student Test, t(39)=6.98, p<0.001). Conclusions Deferasirox proves to be an effective iron chelator, the serum level of ferritine decreased for all the patients during the treatment and 22.5 % of the patients developed an erythroid improvement. Safety and compliance were good.
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Affiliation(s)
- Andrada Viorica Parvu
- Hematology Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Anca Bojan
- Hematology Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Laura Urian
- Hematology Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Tunde Torok
- Hematology Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Iulia Andrea Zsoldos
- Hematology Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Mihaela Iancu
- Medical Informatics and Biostatistics Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
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16
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Iron overload in patients with myelodysplastic syndromes: An updated overview. Cancer 2018; 124:3979-3989. [DOI: 10.1002/cncr.31550] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/07/2018] [Accepted: 03/22/2018] [Indexed: 01/19/2023]
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Myelodysplastic Syndromes and Iron Chelation Therapy. Mediterr J Hematol Infect Dis 2017; 9:e2017021. [PMID: 28293409 PMCID: PMC5333736 DOI: 10.4084/mjhid.2017.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 01/27/2017] [Indexed: 01/19/2023] Open
Abstract
Over recent decades we have been fortunate to witness the advent of new technologies and of an expanded knowledge and application of chelation therapies to the benefit of patients with iron overload. However, extrapolation of learnings from thalassemia to the myelodysplastic syndromes (MDS) has resulted in a fragmented and uncoordinated clinical evidence base. We’re therefore forced to change our understanding of MDS, looking with other eyes to observational studies that inform us about the relationship between iron and tissue damage in these subjects. The available evidence suggests that iron accumulation is prognostically significant in MDS, but levels of accumulation historically associated with organ damage (based on data generated in the thalassemias) are infrequent. Emerging experimental data have provided some insight into this paradox, as our understanding of iron-induced tissue damage has evolved from a process of progressive bulking of organs through high-volumes iron deposition, to one of ‘toxic’ damage inflicted through multiple cellular pathways. Damage from iron may, therefore, occur prior to reaching reference thresholds, and similarly, chelation may be of benefit before overt iron overload is seen. In this review, we revisit the scientific and clinical evidence for iron overload in MDS to better characterize the iron overload phenotype in these patients, which differs from the classical transfusional and non-transfusional iron overload syndrome. We hope this will provide a conceptual framework to better understand the complex associations between anemia, iron and clinical outcomes, to accelerate progress in this area.
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Berendsen RR, Lindeman RC, Boom M, Aarts LPHJ, van Dorp ELA, Teppema LJ. Erythropoietin does not have effects on the ventilatory and pulmonary vascular response to acute hypoxia in men and women. Exp Physiol 2016; 101:1230-1240. [DOI: 10.1113/ep085675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 07/07/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Remco R. Berendsen
- Leiden University Medical Center, Department of Anesthesiology; Leiden The Netherlands
| | | | - Merel Boom
- Leiden University Medical Center, Department of Anesthesiology; Leiden The Netherlands
| | - Leon P. H. J. Aarts
- Leiden University Medical Center, Department of Anesthesiology; Leiden The Netherlands
| | | | - Luc J. Teppema
- Leiden University Medical Center, Department of Anesthesiology; Leiden The Netherlands
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19
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Bart NK, Curtis MK, Cheng HY, Hungerford SL, McLaren R, Petousi N, Dorrington KL, Robbins PA. Elevation of iron storage in humans attenuates the pulmonary vascular response to hypoxia. J Appl Physiol (1985) 2016; 121:537-44. [PMID: 27418684 PMCID: PMC5007321 DOI: 10.1152/japplphysiol.00032.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 07/07/2016] [Indexed: 12/23/2022] Open
Abstract
This study shows that a single dose of intravenous iron reduces the effects of hypoxia on the pulmonary circulation in a manner that persists for at least several weeks. This is long after the foreign iron-sugar complex has been cleared from the blood. It raises the possibility that manipulating iron stores, even in people who are not initially iron deficient, could be used for therapeutic gain in some forms of pulmonary hypertension. Sustained hypoxia over several hours induces a progressive rise in pulmonary artery systolic pressure (PASP). Administration of intravenous iron immediately prior to the hypoxia exposure abrogates this effect, suggesting that manipulation of iron stores may modify hypoxia-induced pulmonary hypertension. Iron (ferric carboxymaltose) administered intravenously has a plasma half-life of 7-12 h. Thus any therapeutic use of intravenous iron would require its effect on PASP to persist long after the iron-sugar complex has been cleared from the blood. To examine this, we studied PASP during sustained (6 h) hypoxia on 4 separate days (days 0, 1, 8, and 43) in 22 participants. On day 0, the rise in PASP with hypoxia was well matched between the iron and saline groups. On day 1, each participant received either 1 g of ferric carboxymaltose or saline in a double-blind manner. After administration of intravenous iron, the rise in PASP with hypoxia was attenuated by ∼50%, and this response remained suppressed on both days 8 and 43 (P < 0.001). Following administration of intravenous iron, values for ferritin concentration, transferrin saturation, and hepcidin concentration rose significantly (P < 0.001, P < 0.005, and P < 0.001, respectively), and values for transferrin concentration fell significantly (P < 0.001). These changes remained significant at day 43. We conclude that the attenuation of the pulmonary vascular response to hypoxia by elevation of iron stores persists long after the artificial iron-sugar complex has been eliminated from the blood. The persistence of this effect suggests that intravenous iron may be of benefit in some forms of pulmonary hypertension.
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Affiliation(s)
- Nicole K Bart
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - M Kate Curtis
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Hung-Yuan Cheng
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Sara L Hungerford
- Department of Medicine, Royal Berkshire NHS Foundation Trust, Reading, United Kingdom; and
| | - Ross McLaren
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Nayia Petousi
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Keith L Dorrington
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom;
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20
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Frise MC, Cheng HY, Nickol AH, Curtis MK, Pollard KA, Roberts DJ, Ratcliffe PJ, Dorrington KL, Robbins PA. Clinical iron deficiency disturbs normal human responses to hypoxia. J Clin Invest 2016; 126:2139-50. [PMID: 27140401 PMCID: PMC4887172 DOI: 10.1172/jci85715] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/10/2016] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Iron bioavailability has been identified as a factor that influences cellular hypoxia sensing, putatively via an action on the hypoxia-inducible factor (HIF) pathway. We therefore hypothesized that clinical iron deficiency would disturb integrated human responses to hypoxia. METHODS We performed a prospective, controlled, observational study of the effects of iron status on hypoxic pulmonary hypertension. Individuals with absolute iron deficiency (ID) and an iron-replete (IR) control group were exposed to two 6-hour periods of isocapnic hypoxia. The second hypoxic exposure was preceded by i.v. infusion of iron. Pulmonary artery systolic pressure (PASP) was serially assessed with Doppler echocardiography. RESULTS Thirteen ID individuals completed the study and were age- and sex-matched with controls. PASP did not differ by group or study day before each hypoxic exposure. During the first 6-hour hypoxic exposure, the rise in PASP was 6.2 mmHg greater in the ID group (absolute rises 16.1 and 10.7 mmHg, respectively; 95% CI for difference, 2.7-9.7 mmHg, P = 0.001). Intravenous iron attenuated the PASP rise in both groups; however, the effect was greater in ID participants than in controls (absolute reductions 11.1 and 6.8 mmHg, respectively; 95% CI for difference in change, -8.3 to -0.3 mmHg, P = 0.035). Serum erythropoietin responses to hypoxia also differed between groups. CONCLUSION Clinical iron deficiency disturbs normal responses to hypoxia, as evidenced by exaggerated hypoxic pulmonary hypertension that is reversed by subsequent iron administration. Disturbed hypoxia sensing and signaling provides a mechanism through which iron deficiency may be detrimental to human health. TRIAL REGISTRATION ClinicalTrials.gov (NCT01847352). FUNDING M.C. Frise is the recipient of a British Heart Foundation Clinical Research Training Fellowship (FS/14/48/30828). K.L. Dorrington is supported by the Dunhill Medical Trust (R178/1110). D.J. Roberts was supported by R&D funding from National Health Service (NHS) Blood and Transplant and a National Institute for Health Research (NIHR) Programme grant (RP-PG-0310-1004). This research was funded by the NIHR Oxford Biomedical Research Centre Programme.
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Affiliation(s)
- Matthew C. Frise
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Hung-Yuan Cheng
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Annabel H. Nickol
- Oxford University Hospitals NHS Foundation Trust, Oxford Centre for Respiratory Medicine, Churchill Hospital, Oxford, United Kingdom
| | - M. Kate Curtis
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Karen A. Pollard
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - David J. Roberts
- University of Oxford, Nuffield Department of Clinical Laboratory Sciences, and National Health Service Blood and Transplant Oxford Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Peter J. Ratcliffe
- University of Oxford, Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, Old Road Campus, Headington, Oxford, United Kingdom
| | - Keith L. Dorrington
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Peter A. Robbins
- University of Oxford, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
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21
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Frise MC, Robbins PA. Iron, oxygen, and the pulmonary circulation. J Appl Physiol (1985) 2015; 119:1421-31. [PMID: 26066825 PMCID: PMC4683351 DOI: 10.1152/japplphysiol.00179.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 06/05/2015] [Indexed: 12/24/2022] Open
Abstract
The human pulmonary vasculature vasoconstricts in response to a reduction in alveolar oxygen tension, a phenomenon termed hypoxic pulmonary vasoconstriction (HPV). This review describes the time course of this behavior, which occurs in distinct phases, and then explores the importance for HPV of the hypoxia-inducible factor (HIF) pathway. Next, the HIF-hydroxylase enzymes that act as molecular oxygen sensors within the HIF pathway are discussed. These enzymes are particularly sensitive to intracellular iron availability, which confers iron-sensing properties on the HIF pathway. Human studies of iron chelation and supplementation are then reviewed. These demonstrate that the iron sensitivity of the HIF pathway evident from in vitro experiments is relevant to human pulmonary vascular physiology. Next, the importance of iron status in high-altitude illness and chronic cardiopulmonary disease is explored, and the therapeutic potential of intravenous iron discussed. The review concludes by highlighting some further complexities that arise from interactions between the HIF pathway and other intracellular iron-sensing mechanisms.
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Affiliation(s)
- Matthew C Frise
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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22
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Durable Red Blood Cell Transfusion Independence in a Patient with an MDS/MPN Overlap Syndrome Following Discontinuation of Iron Chelation Therapy. Case Rep Hematol 2015; 2015:253294. [PMID: 25918650 PMCID: PMC4396885 DOI: 10.1155/2015/253294] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/11/2015] [Accepted: 03/06/2015] [Indexed: 01/14/2023] Open
Abstract
Background. Hematologic improvement (HI) occurs in some patients with acquired anemias and transfusional iron overload receiving iron chelation therapy (ICT) but there is little information on transfusion status after stopping chelation. Case Report. A patient with low IPSS risk RARS-T evolved to myelofibrosis developed a regular red blood cell (RBC) transfusion requirement. There was no response to a six-month course of study medication or to erythropoietin for three months. At 27 months of transfusion dependence, she started deferasirox and within 6 weeks became RBC transfusion independent, with the hemoglobin normalizing by 10 weeks of chelation. After 12 months of chelation, deferasirox was stopped; she remains RBC transfusion independent with a normal hemoglobin 17 months later. We report the patient's course in detail and review the literature on HI with chelation. Discussion. There are reports of transfusion independence with ICT, but that transfusion independence may be sustained long term after stopping chelation deserves emphasis. This observation suggests that reduction of iron overload may have a lasting favorable effect on bone marrow failure in at least some patients with acquired anemias.
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23
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Frise MC, Robbins PA. The pulmonary vasculature--lessons from Tibetans and from rare diseases of oxygen sensing. Exp Physiol 2014; 100:1233-41. [PMID: 26575340 DOI: 10.1113/expphysiol.2014.080507] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/05/2014] [Indexed: 12/11/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review is principally concerned with results from studies of the pulmonary vasculature in humans, particularly in relation to hypoxia and rare diseases that affect oxygen sensing. What advances does it highlight? This review highlights the degree to which the hypoxia-inducible factor (HIF) transcription system influences human pulmonary vascular responses to hypoxia. Upregulation of the HIF pathway augments hypoxic pulmonary vasoconstriction, while alterations to the pathway found in Tibetans are associated with suppression of the progressive increase in pulmonary artery pressure with sustained hypoxia. It also highlights the potential importance of iron, which modulates the HIF pathway, in modifying the pulmonary vascular response to hypoxia. The human pulmonary circulation loses its natural distensibility during sustained hypoxia, leading to pulmonary arterial hypertension and a much higher workload for the right ventricle. The hypoxia-inducible factor (HIF) pathway is implicated in this pulmonary vascular response to continued hypoxia by animal studies, and additionally, by rare human diseases where the pathway is upregulated. However, there are no known human genetic diseases downregulating HIF. Tibetans, though, demonstrate blunted pulmonary vascular responses to sustained hypoxia. This seems to be accounted for by an altered HIF pathway as a consequence of natural selection over a period of many thousands of years lived at high altitude. In addition to genetic differences, iron is another important modulator of HIF pathway function. Experimental work in humans demonstrates that manipulation of iron stores can influence the behaviour of the pulmonary circulation during hypoxia, in ways analogous to that seen in Tibetans and patients with rare diseases that affect oxygen sensing. The importance of physiological differences in iron bioavailability in modulating hypoxic pulmonary vasoconstriction in health and disease is yet to be established.
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Affiliation(s)
- Matthew C Frise
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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24
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Jiang L, Peng WW, Li LF, Du R, Wu TT, Zhou ZJ, Zhao JJ, Yang Y, Qu DL, Zhu YQ. Effects of deferoxamine on the repair ability of dental pulp cells in vitro. J Endod 2014; 40:1100-4. [PMID: 25069915 DOI: 10.1016/j.joen.2013.12.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 11/25/2013] [Accepted: 12/06/2013] [Indexed: 01/07/2023]
Abstract
INTRODUCTION In previous studies, we found that hypoxia promoted the mineralization of dental pulp cells (DPCs). However, the clinical application of hypoxia as a therapy is questionable or unfeasible. Deferoxamine (DFO), a medication for iron overload, has also been shown to induce hypoxia. The purpose of this study was to investigate the effects of DFO on the repair ability of DPCs. METHODS DPCs were obtained by using a tissue explant technique in vitro and were treated with different concentrations of DFO or hypoxia culture for 2 days. The viability, proliferation, migration, and odontogenic differentiation of DPCs were assayed and analyzed. The expression of hypoxia-inducible factor 1-alpha (HIF-1α) was assessed through Western blotting. RESULTS Ten micromolars of DFO enhanced the expression of HIF-1α similarly to hypoxia and did not affect the viability of DPCs for 2 days. Furthermore, the proliferation, migration, and odontogenic differentiation of DPCs were promoted by DFO. CONCLUSIONS These results suggest that DFO might improve the repair ability of DPCs by HIF-1α.
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Affiliation(s)
- Long Jiang
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Wei-Wei Peng
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Li-Fen Li
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Rong Du
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Tian-Tian Wu
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Zhuo-Jun Zhou
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Jun-Jun Zhao
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Ya Yang
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Dong-Lin Qu
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Ya-Qin Zhu
- Department of General Dentistry, 9th People's Hospital, Shanghai JiaoTong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
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25
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Molteni A, Riva M, Pellizzari A, Borin L, Freyre A, Greco R, Ubezio M, Bernardi M, Fariciotti A, Nador G, Nichelatti M, Ravano E, Morra E. Hematological improvement during iron-chelation therapy in myelodysplastic syndromes: The experience of the “Rete Ematologica Lombarda”. Leuk Res 2013; 37:1233-40. [DOI: 10.1016/j.leukres.2013.07.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 07/01/2013] [Indexed: 12/16/2022]
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26
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Wong CM, Preston IR, Hill NS, Suzuki YJ. Iron chelation inhibits the development of pulmonary vascular remodeling. Free Radic Biol Med 2012; 53:1738-47. [PMID: 22974762 PMCID: PMC3472156 DOI: 10.1016/j.freeradbiomed.2012.08.576] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Revised: 08/15/2012] [Accepted: 08/17/2012] [Indexed: 12/15/2022]
Abstract
Reactive oxygen species (ROS) have been implicated in the pathogenesis of pulmonary hypertension. Because iron is an important regulator of ROS biology, this study examined the effects of iron chelation on the development of pulmonary vascular remodeling. The administration of an iron chelator, deferoxamine, to rats prevented chronic hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. Various iron chelators inhibited the growth of cultured pulmonary artery smooth muscle cells. Protein carbonylation, an important iron-dependent biological event, was promoted in association with pulmonary vascular remodeling and cell growth. A proteomic approach identified that Rho GDP-dissociation inhibitor (a negative regulator of RhoA) is carbonylated. In human plasma, the protein carbonyl content was significantly higher in patients with idiopathic pulmonary arterial hypertension than in healthy controls. These results suggest that iron plays an important role in the ROS-dependent mechanism underlying the development of pulmonary hypertension.
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Affiliation(s)
- Chi-Ming Wong
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20057, USA
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27
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Human apo-lactoferrin as a physiological mimetic of hypoxia stabilizes hypoxia-inducible factor-1 alpha. Biometals 2012; 25:1247-59. [DOI: 10.1007/s10534-012-9586-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 09/06/2012] [Indexed: 01/02/2023]
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28
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Fragiadaki M, Hill N, Hewitt R, Bou-Gharios G, Cook T, Tam FW, Domin J, Mason RM. Hyperglycemia causes renal cell damage via CCN2-induced activation of the TrkA receptor: implications for diabetic nephropathy. Diabetes 2012; 61:2280-8. [PMID: 22586581 PMCID: PMC3425410 DOI: 10.2337/db11-1138] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
CCN2, a secreted profibrotic protein, is highly expressed in diabetic nephropathy (DN) and implicated in its pathogenesis; however, the actions of CCN2 in DN remain elusive. We previously demonstrated that CCN2 triggers signaling via tropomyosin receptor kinase A (TrkA). Trace expression of TrkA is found in normal kidneys, but its expression is elevated in several nephropathies; yet its role in DN is unexplored. In this study we show de novo expression of TrkA in human and murine DN. We go on to study the molecular mechanisms leading to TrkA activation and show that it involves hypoxia, as demonstrated by ischemia-reperfusion injury and in vitro experiments mimicking hypoxia, implicating hypoxia as a common pathway leading to disease. We also expose renal cells to hyperglycemia, which led to TrkA phosphorylation in mesangial cells, tubular epithelial cells, and podocytes but not in glomerular endothelial cells and renal fibroblasts. In addition, we report that hyperglycemia caused an induction of phosphorylated extracellular signal-related kinase 1/2 and Snail1 that was abrogated by silencing of TrkA or CCN2 using small interfering RNA. In conclusion, we provide novel evidence that TrkA is activated in diabetic kidneys and suggest that anti-TrkA therapy may prove beneficial in DN.
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Affiliation(s)
- Maria Fragiadaki
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Corresponding authors: Roger M. Mason, , and Maria Fragiadaki, or
| | - Nicola Hill
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
| | - Reiko Hewitt
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
| | - George Bou-Gharios
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Kennedy Institute of Rheumatology, Imperial College London, London, U.K
| | - Terence Cook
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Histopathology, Imperial College London, London, U.K
| | - Frederick W. Tam
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
| | - Jan Domin
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Division of Sciences, University of Bedfordshire, Luton, U.K
| | - Roger M. Mason
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Corresponding authors: Roger M. Mason, , and Maria Fragiadaki, or
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Abstract
Patients with β-thalassemia major (TM) and other refractory anemias requiring regular blood transfusions accumulate iron that damages the liver, endocrine system, and most importantly the heart. The prognosis in TM has improved remarkably over the past 10 years. This improvement has resulted from the development of magnetic resonance imaging (MRI) techniques, especially T2*, to accurately measure cardiac and liver iron, and from the availability of 3 iron-chelating drugs. In this article we describe the use of MRI to determine which adult and pediatric patients need to begin iron chelation therapy and to monitor their progress. We summarize the properties of each of the 3 drugs, deferoxamine (DFO), deferiprone (DFP), and deferasirox (DFX), including their efficacy, patient acceptability, and side effects. We describe when to initiate or intensify therapy, switch to another drug, or use combined therapy. We also discuss the management of refractory anemias other than TM that may require multiple blood transfusions, including sickle cell anemia and myelodysplasia. The development of a potential fourth chelator FBS 0701 and the combined use of oral chelators may further improve the quality of life and survival in patients with TM and other transfusion-dependent patients.
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Leitch HA. Optimizing therapy for iron overload in the myelodysplastic syndromes: recent developments. Drugs 2011; 71:155-77. [PMID: 21275444 DOI: 10.2165/11585280-000000000-00000] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The myelodysplastic syndromes (MDS) are characterized by cytopenias and risk of progression to acute myeloid leukaemia (AML). Most MDS patients eventually require transfusion of red blood cells for anaemia, placing them at risk of transfusional iron overload. In β-thalassaemia major, transfusional iron overload leads to organ dysfunction and death; however, with iron chelation therapy, organ function is improved, and survival improved to near normal and correlated with the degree of compliance with chelation. In lower-risk MDS, several nonrandomized studies suggest an adverse effect of iron overload on survival and that lowering iron with chelation may minimize this impact. Emerging data indicate that chelation may improve organ function, particularly hepatic function, and a minority of patients may have improvement in cell counts and decreased transfusion requirements. While guidelines for MDS generally recommend chelation in selected lower-risk patients, data from nonrandomized trials suggest iron overload may impact adversely on the outcome of higher-risk MDS and stem cell transplantation (SCT). This effect may be due to increased transplant-related mortality, infection and AML progression, and preliminary data suggest that lowering iron may be beneficial in this patient group. Other areas of active and future investigation include optimizing the monitoring of iron overload using imaging such as T2* MRI and measures of labile iron and oxidative stress; correlating new methods of measuring iron to clinical outcomes; clarifying the contribution of different cellular and extracellular iron pools to iron toxicity; optimizing chelation by using agents that access the appropriate iron pools to minimize the relevant clinical consequences in individual patients; and incorporating measures of quality of life and co-morbidities into clinical trials of chelation in MDS. It should be noted that chelation is costly and potentially toxic, and in MDS should be initiated after weighing potential risks and benefits for each patient until more definitive data are available. In this review, data on the impact of iron overload in MDS and SCT are discussed; for example, several noncontrolled studies show inferior survival in patients with iron overload in these clinical settings, including an increase in transplant-related mortality and infection risk. Possible mechanisms of iron toxicity include oxidative stress, which can damage cellular components, and the documented impact of lowering iron on organ function with measures such as iron chelation therapy includes an improvement in elevated liver transaminases. Lowering iron also appears to improve survival in both lower-risk MDS and SCT in nonrandomized studies. Selected aspects of iron metabolism, transport, storage and distribution that may be amenable to future intervention and improved removal of iron from important cellular sites are discussed, as are attempts to quantify quality of life and the importance of co-morbidities in measures to treat MDS, including chelation therapy.
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Affiliation(s)
- Heather A Leitch
- Division of Hematology, St Paul's Hospital and the University of British Columbia, 440–1144 Burrard Street, Vancouver, BC, Canada.
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31
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Teppema LJ, Dahan A. The Ventilatory Response to Hypoxia in Mammals: Mechanisms, Measurement, and Analysis. Physiol Rev 2010; 90:675-754. [DOI: 10.1152/physrev.00012.2009] [Citation(s) in RCA: 257] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The respiratory response to hypoxia in mammals develops from an inhibition of breathing movements in utero into a sustained increase in ventilation in the adult. This ventilatory response to hypoxia (HVR) in mammals is the subject of this review. The period immediately after birth contains a critical time window in which environmental factors can cause long-term changes in the structural and functional properties of the respiratory system, resulting in an altered HVR phenotype. Both neonatal chronic and chronic intermittent hypoxia, but also chronic hyperoxia, can induce such plastic changes, the nature of which depends on the time pattern and duration of the exposure (acute or chronic, episodic or not, etc.). At adult age, exposure to chronic hypoxic paradigms induces adjustments in the HVR that seem reversible when the respiratory system is fully matured. These changes are orchestrated by transcription factors of which hypoxia-inducible factor 1 has been identified as the master regulator. We discuss the mechanisms underlying the HVR and its adaptations to chronic changes in ambient oxygen concentration, with emphasis on the carotid bodies that contain oxygen sensors and initiate the response, and on the contribution of central neurotransmitters and brain stem regions. We also briefly summarize the techniques used in small animals and in humans to measure the HVR and discuss the specific difficulties encountered in its measurement and analysis.
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Affiliation(s)
- Luc J. Teppema
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Albert Dahan
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
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Nagel S, Talbot NP, Mecinović J, Smith TG, Buchan AM, Schofield CJ. Therapeutic manipulation of the HIF hydroxylases. Antioxid Redox Signal 2010; 12:481-501. [PMID: 19754349 DOI: 10.1089/ars.2009.2711] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The hypoxia-inducible factor (HIF) family of transcription factors is responsible for coordinating the cellular response to low oxygen levels in animals. By regulating the expression of a large array of target genes during hypoxia, these proteins also direct adaptive changes in the hematopoietic, cardiovascular, and respiratory systems. They also play roles in pathological processes, including tumorogenesis. In recent years, several oxygenases have been identified as key molecular oxygen sensors within the HIF system. The HIF hydroxylases regulate the stability and transcriptional activity of the HIF-alpha subunit by catalyzing hydroxylation of specific proline and asparaginyl residues, respectively. They require oxygen and 2-oxoglutarate (2OG) as co-substrates, and depend upon non-heme ferrous iron (Fe(II)) as a cofactor. This article summarizes current understanding of the biochemistry of the HIF hydroxylases, identifies targets for their pharmacological manipulation, and discusses their potential in the therapeutic manipulation of the HIF system.
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Affiliation(s)
- Simon Nagel
- Acute Stroke Programme, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Headington, Oxford, United Kingdom
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33
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Red blood cell transfusion independence following the initiation of iron chelation therapy in myelodysplastic syndrome. Adv Hematol 2010; 2010:164045. [PMID: 20368773 PMCID: PMC2846339 DOI: 10.1155/2010/164045] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 01/11/2010] [Accepted: 01/18/2010] [Indexed: 01/02/2023] Open
Abstract
Iron chelation therapy is often used to treat iron overload in patients requiring transfusion of red blood cells (RBC). A 76-year-old man with MDS type refractory cytopenia with multilineage dysplasia, intermediate-1 IPSS risk, was referred when he became transfusion dependent. He declined infusional chelation but subsequently accepted oral therapy. Following the initiation of chelation, RBC transfusion requirement ceased and he remained transfusion independent over 40 months later. Over the same time course, ferritin levels decreased but did not normalize. There have been eighteen other MDS patients reported showing improvement in hemoglobin level with iron chelation; nine became transfusion independent, nine had decreased transfusion requirements, and some showed improved trilineage myelopoiesis. The clinical features of these patients are summarized and possible mechanisms for such an effect of iron chelation on cytopenias are discussed.
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Chen TL, Sheu MT, Liang YC, Lin YJ, Hsieh MS, Chen CH. Disease-modifying Effects of Glucosamine on Interleukin-1β-treated Chondrosarcoma Cells (SW1353) Under Normoxic and Hypoxic Conditions. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1878-3317(10)60004-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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35
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Abstract
Oxygen is essential for the maintenance of life, and when oxygen levels decline to critical levels, a program of complex mechanisms exists to i) sense hypoxia, ii) respond to minimize acute tissue injury, and iii) result in adaptations that offer protection against further hypoxia challenges. Alternative adaptation-related protection may also be inducible through the increased activity of hypoxia-inducible factors activated by hypoxia mimics such as iron chelation with deferoxamine (DFA). We have characterized a set of hypoxia-related responses at the microvasculature and postulated that microvascular injury in response to hypoxia could be reproduced by the reduction of bioavailable iron through chelation by DFA. We were able to induce a similar degree of leukocyte adherence and emigration and vascular leak with DFA infusion as compared with hypoxia exposure in an intact physiological rodent model. However, in contrast to hypoxia-exposed groups, we were unable to detect reactive oxygen species or alter the injury pattern with reactive oxygen species scavenger in the groups treated with DFA. Thus, we demonstrate that DFA mimics the pattern and intensity of hypoxia-related injury on the microvasculature; however, differences in the time course and mechanism of injury were identified. In addition, DFA saturated with iron did not completely reverse the effects of DFA, suggesting a mechanism(s) beyond a reduction in the bioavailability of iron. These findings may have importance in the targeting of iron for the development of hypoxia mimics that may offer protection against subsequent hypoxia exposure in clinical setting such as myocardial infarction and stroke.
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Smith TG, Balanos GM, Croft QPP, Talbot NP, Dorrington KL, Ratcliffe PJ, Robbins PA. The increase in pulmonary arterial pressure caused by hypoxia depends on iron status. J Physiol 2008; 586:5999-6005. [PMID: 18955380 PMCID: PMC2655431 DOI: 10.1113/jphysiol.2008.160960] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hypoxia is a major cause of pulmonary hypertension. Gene expression activated by the transcription factor hypoxia-inducible factor (HIF) is central to this process. The oxygen-sensing iron-dependent dioxygenase enzymes that regulate HIF are highly sensitive to varying iron availability. It is unknown whether iron similarly influences the pulmonary vasculature. This human physiology study aimed to determine whether varying iron availability affects pulmonary arterial pressure and the pulmonary vascular response to hypoxia, as predicted biochemically by the role of HIF. In a controlled crossover study, 16 healthy iron-replete volunteers undertook two separate protocols. The ‘Iron Protocol’ studied the effects of an intravenous infusion of iron on the pulmonary vascular response to 8 h of sustained hypoxia. The ‘Desferrioxamine Protocol’ examined the effects of an 8 h intravenous infusion of the iron chelator desferrioxamine on the pulmonary circulation. Primary outcome measures were pulmonary artery systolic pressure (PASP) and the PASP response to acute hypoxia (ΔPASP), assessed by Doppler echocardiography. In the Iron Protocol, infusion of iron abolished or greatly reduced both the elevation in baseline PASP (P < 0.001) and the enhanced sensitivity of the pulmonary vasculature to acute hypoxia (P = 0.002) that are induced by exposure to sustained hypoxia. In the Desferrioxamine Protocol, desferrioxamine significantly elevated both PASP (P < 0.001) and ΔPASP (P = 0.01). We conclude that iron availability modifies pulmonary arterial pressure and pulmonary vascular responses to hypoxia. Further research should investigate the potential for therapeutic manipulation of iron status in the management of hypoxic pulmonary hypertensive disease.
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Affiliation(s)
- Thomas G Smith
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
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37
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Abstract
When humans are exposed to hypoxia, systemic and intracellular changes operate together to minimise hypoxic injury and restore adequate oxygenation. Emerging evidence indicates that the hypoxia-inducible factor (HIF) family of transcription factors plays a central regulatory role in these homeostatic changes at both the systemic and cellular levels. HIF was discovered through its action as the transcriptional activator of erythropoietin, and has subsequently been found to control intracellular hypoxic responses throughout the body. HIF is primarily regulated by specific prolyl hydroxylase-domain enzymes (PHDs) that initiate its degradation via the von Hippel-Lindau tumour suppressor protein (VHL). The oxygen and iron dependency of PHD activity accounts for regulation of the pathway by both cellular oxygen and iron status. Recent studies conducted in patients with rare genetic diseases have begun to uncover the wider importance of the PHD-VHL-HIF axis in systems-level human biology. These studies indicate that, in addition to regulating erythropoiesis, the system plays an important role in cardiopulmonary regulation. This article reviews our current understanding of the importance of HIF in human systems-level physiology, and is modelled around the classic physiological response to high-altitude hypoxia.
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Affiliation(s)
- Thomas G Smith
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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38
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Liu C, Balanos GM, Fatemian M, Smith TG, Dorrington KL, Robbins PA. Effects of hydralazine on the pulmonary vasculature and respiratory control in humans. Exp Physiol 2007; 93:104-14. [PMID: 17911356 DOI: 10.1113/expphysiol.2007.039750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study sought: (1) to clarify the effects of hydralazine on both the pulmonary vasculature and respiratory control in euoxia and hypoxia in healthy humans; and (2) to determine whether hydralazine alters the expression of genes regulated by hypoxia-inducible factor 1 (HIF-1). Ten volunteers participated in two 2 day protocols. Hydralazine (25 mg) or placebo was administered at 1 pm and 11 pm on the first day, and at 1 pm on the second day. In the mornings and afternoons of both days, we measured plasma vascular endothelial growth factor (VEGF) and erythropoietin (EPO) concentrations (both HIF-1-regulated gene products), systemic arterial blood pressure, and changes in heart rate, cardiac output, maximal systolic pressure difference across the tricuspid valve (delta Pmax) and ventilation in response to 20 min of isocapnic hypoxia. Recent hydralazine: (1) decreased diastolic blood pressure; (2) increased heart rate and cardiac output in euoxia and hypoxia whilst having no effect on delta Pmax; and (3) increased the ventilatory sensitivity to hypoxia. Hydralazine had no effect on plasma EPO or VEGF concentration. We conclude that hydralazine increases the sensitivity of the ventilatory response to hypoxia, but lacks any effect on the pulmonary vasculature at the dose studied. It did not affect the expression of HIF-1-regulated genes.
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Affiliation(s)
- Chun Liu
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
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39
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O'Donnell A, Premawardhena A, Arambepola M, Allen SJ, Peto TEA, Fisher CA, Rees DC, Olivieri NF, Weatherall DJ. Age-related changes in adaptation to severe anemia in childhood in developing countries. Proc Natl Acad Sci U S A 2007; 104:9440-4. [PMID: 17517643 PMCID: PMC1890513 DOI: 10.1073/pnas.0703424104] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Indexed: 12/30/2022] Open
Abstract
Severe forms of anemia in children in the developing countries may be characterized by different clinical manifestations at particular stages of development. Whether this reflects developmental changes in adaptation to anemia or other mechanisms is not clear. The pattern of adaptation to anemia has been assessed in 110 individuals with hemoglobin (Hb) E beta-thalassemia, one of the commonest forms of inherited anemia in Asia. It has been found that age and Hb levels are independent variables with respect to erythropoietin response and that there is a decline in the latter at a similar degree of anemia during development. To determine whether this finding is applicable to anemia due to other causes, a similar study has been carried out on 279 children with severe anemia due to Plasmodium falciparum malaria; the results were similar to those in the patients with thalassemia. These observations may have important implications both for the better understanding of the pathophysiology of profound anemia in early life and for its more logical and cost-effective management.
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Affiliation(s)
- Angela O'Donnell
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX 3 9DS, United Kingdom.
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40
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Nguyen MVC, Pouvreau S, El Hajjaji FZ, Denavit-Saubie M, Pequignot JM. Desferrioxamine enhances hypoxic ventilatory response and induces tyrosine hydroxylase gene expression in the rat brainstem in vivo. J Neurosci Res 2007; 85:1119-25. [PMID: 17304568 DOI: 10.1002/jnr.21202] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The iron chelator desferrioxamine (DFO) induces accumulation of the hypoxia-inducible factor (HIF-1), a transcription factor that up-regulates genes involved in adaptative responses to hypoxia. This property makes DFO a potential neuroprotector against hypoxic stress. We investigated in rats the effects of DFO on the ventilatory response to mild hypoxic tests and the expression of tyrosine hydroxylase (TH), a target gene of HIF-1. Two protocols were used, the first with repeated injections of 50 mg/kg DFO every 2 days during a 2-week period. This was aimed at define the time course of the ventilatory responses to a hypoxic test. In the second protocol, rats were given a single injection of 300 mg/kg DFO. Every day over 4 days, the hypoxic ventilatory response was recorded before the animal was sacrificed, and Western blot analysis of TH in the dorsal brainstem cardiorespiratory area was performed. DFO produced a delayed increase in the hypoxic ventilatory response, which appeared in the same time window as TH up-regulation (2-3 days after the bolus injection of DFO). This delay suggests a genic effect of the drug that improves the ventilatory response to hypoxia.
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Affiliation(s)
- M V C Nguyen
- CNRS UPR 2216, Neurobiologie Génétique et Intégrative, Institut Alfred Fessard, Gif/Yvette, France.
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41
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Abstract
Erythropoietin (EPO) gene expression is under the control of inhibitory (GATA-2, NF-kappaB) and stimulatory (hypoxia-inducible transcription factor [HIF]-2, hepatocyte nuclear factor [HNF]-4alpha [alpha]) transcription factors. EPO deficiency is the main cause of the anemia in chronic kidney disease (CKD) and a contributing factor in the anemias of inflammation and cancer. Small, orally active compounds capable of stimulating endogenous EPO production are in preclinical or clinical trials for treatment of anemia. These agents include stabilizers of the HIFs that bind to the EPO enhancer and GATA inhibitors which prevent GATA from suppressing the EPO promoter. While HIF stabilizing drugs may prove useful as inexpensive second-line choices, at present, their side effects--particularly tumorigenicity--preclude their use as first-choice therapy. As an alternative, EPO gene therapy has been explored in animal studies and in trials on CKD patients. Here, a major problem is immunogenicity of ex vivo transfected implanted cells and of the recombinant protein produced after ex vivo or in vivo EPO complementary DNA (cDNA) transfer. Recombinant human EPO (rhEPO) engineered in Chinese hamster ovary (CHO) cell cultures (epoetin alpha and epoetin beta [beta]) and its hyperglycosylated analogue darbepoetin alpha are established and safe drugs to avoid allogeneic red blood cell transfusion. Gene-activated EPO (epoetin delta [delta]) from human fibrosarcoma cells (HT-1080) has recently been launched for use in CKD. It is important to know the basics of the technologies, production processes, and structural properties of the novel anti-anemic strategies and drugs.
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42
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Hulter HN, Krapf R. Interrelationships Among Hypoxia-Inducible Factor Biology and Acid-Base Equilibrium. Semin Nephrol 2006; 26:454-65. [PMID: 17275583 DOI: 10.1016/j.semnephrol.2006.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In this article, we try to summarize the most important novel biological information on the complex interrelationships between acid-base alterations and hypoxia-inducible factor (HIF) signaling. Extracellular and intracellular acid-base alterations affect HIF signaling in part independently of hypoxia, and involve, among others, effects on cytoprotection and apoptosis. Conversely, HIF signaling may affect systemic and local acid production rates and has been implicated in the mechanism of the acute hyperventilatory response (ie, respiratory alkalosis) in response to hypoxia as well as for hypoxia-induced pulmonary artery hypertension (PAH), although the latter data are quite preliminary and can be explained by alternative mechanisms. Thus, this review calls attention to these relationships for renal physiologists and nephrologists to stimulate focused clinical observations and specific investigative efforts as proposed in this overview.
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Affiliation(s)
- Henry N Hulter
- Department of Medicine, University of California at San Francisco, San Francisco, CA, USA
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43
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Lee MY, Joung YH, Lim EJ, Park JH, Ye SK, Park T, Zhang Z, Park DK, Lee KJ, Yang YM. Phosphorylation and activation of STAT proteins by hypoxia in breast cancer cells. Breast 2006; 15:187-95. [PMID: 16084091 DOI: 10.1016/j.breast.2005.05.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 03/09/2005] [Accepted: 05/13/2005] [Indexed: 11/15/2022] Open
Abstract
Several constitutively activated signal transducers and activators of transcription (STAT) proteins have been observed in a wide number of human cancer cell lines and primary tumors. Normal cells maintain normoxic conditions but tumor cells are characteristically hypoxic. We studied the altered activation and tyrosine phosphorylation of STATs under hypoxic conditions (2% O2) or desferrioxamine (DFO) treatment in mouse mammary epithelial cells (HC11) and a human breast cancer cell line (MCF-7). STAT1, -3 and -5 proteins are especially important and are observed at elevated levels in tumorigenesis. We also investigated the serine phosphorylation of STAT1, -3, and -5 under hypoxic conditions or DFO treatment in HC11 and MCF-7 cells. Here we show that DFO or hypoxia stimulates the tyrosine and/or serine phosphorylation and the expression of STAT proteins in breast cancer cells. Our data suggest that DFO or hypoxic condition is a critical stimulator for the activation of STAT proteins in breast cancer cells. These results may provide the basis for identifying another mechanism of breast tumorigenesis via the JAK/STAT pathway in hypoxia. Also, activation of STAT proteins by hypoxia may play an important role in the physiological phenomenon of embryonic stem cells and old cells with hypoxic conditions.
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Affiliation(s)
- Moon Young Lee
- Laboratory of Human Genetics, Department of Pathology, College of Medicine and Bio-Food and Drug Research Center at Konkuk University, Chungju 380-701, Korea
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Lahiri S, Roy A, Li J, Baby SM, Mokashi A, Di Giulio C. Role of Fe2+ in oxygen sensing in the carotid body. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2005; 551:59-64. [PMID: 15602944 DOI: 10.1007/0-387-27023-x_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- S Lahiri
- Dept of Physiology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA
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45
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Salahudeen AK. Cold ischemic injury of transplanted kidneys: new insights from experimental studies. Am J Physiol Renal Physiol 2004; 287:F181-7. [PMID: 15271685 DOI: 10.1152/ajprenal.00098.2004] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Kidney transplantation is the preferred and definitive treatment for end-stage renal disease (ESRD), and kidneys from deceased donors are a major source for it. These kidneys are routinely cold stored to prolong viability, which, however, when prolonged can cause injury, resulting in reduced graft function and survival. Recent experimental studies have identified the release of iron and free radicals, activation of calpain, and formation of F2-isoprostanes as important components of cold ischemic injury, as are the swelling of mitochondria and activation of mitochondrial apoptotic pathways. Moreover, studies have also suggested that fortifying the storage solution with deferoxamine or preconditioning the donor kidneys with hemeoxygenase-1 may prove viable clinical strategies to limit cold ischemic injury. This review will summarize these and other new experimental data that have implications for reducing cold ischemic transplant injury, a step necessary to improve deceased-donor allograft survival.
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Affiliation(s)
- Abdulla K Salahudeen
- Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA.
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46
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Abstract
The glycoprotein hormone erythropoietin (EPO) is an essential viability and growth factor for the erythrocytic progenitors. EPO is mainly produced in the kidneys. EPO gene expression is induced by hypoxia-inducible transcription factors (HIF). The principal representative of the HIF-family (HIF-1, -2 and -3) is HIF-1, which is composed of an O2-labile alpha-subunit and a constant nuclear beta-subunit. In normoxia, the alpha-subunit of HIF is inactivated following prolyl- and asparaginyl-hydroxylation by means of alpha-oxoglutarate and Fe(2+)-dependent HIF specific dioxygenases. While HIF-1 and HIF-2 activate the EPO gene, HIF-3, GATA-2 and NFkappaB are likely inhibitors of EPO gene transcription. EPO signalling involves tyrosine phosphorylation of the homodimeric EPO receptor and subsequent activation of intracellular antiapoptotic proteins, kinases and transcription factors. Lack of EPO leads to anemia. Treatment with recombinant human EPO (rHuEPO) is efficient and safe in improving the management of the anemia associated with chronic renal failure. RHuEPO analogues with prolonged survival in circulation have been developed. Whether the recent demonstration of EPO receptors in various non-hemopoietic tissues, including tumor cells, is welcome or ominous still needs to be clarified. Evidence suggests that rHuEPO may be a useful neuroprotective agent.
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47
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Roy A, Li J, Baby SM, Mokashi A, Buerk DG, Lahiri S. Effects of iron-chelators on ion-channels and HIF-1α in the carotid body. Respir Physiol Neurobiol 2004; 141:115-23. [PMID: 15239962 DOI: 10.1016/j.resp.2004.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2004] [Indexed: 10/26/2022]
Abstract
Acute hypoxia instantaneously increases the chemosensory discharge from the carotid body, increasing ventilation mostly by inhibiting the oxygen sensitive ion channels and exciting the mitochondrial functions in the glomus cells. On the other hand, Fe2+-chelation mimics hypoxia by inhibiting the prolyl hydroxylases and the degradation of HIF-1alpha in non-excitable cells. Whether Fe2+-chelation can inhibit the ion channels giving rise to the sensory responses in excitable cells was the question. We characterized the responses to Fe2+-chelators on excitable glomus cells of the rat, and found that they instantaneously blocked the ion-channels, exciting the chemosensory discharge, and later causing a gradual accumulation of HIF-1alpha. Although initiated by the same stimuli, the two effects (on ion channels and cytosolic HIF-1alpha) possibly occurred by two different mechanisms.
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Affiliation(s)
- Arijit Roy
- Department of Physiology, University of Pennsylvania Medical Center, Philadelphia, PA 19104-6085, USA
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Maxwell P. HIF-1: an oxygen response system with special relevance to the kidney. J Am Soc Nephrol 2004; 14:2712-22. [PMID: 14569080 DOI: 10.1097/01.asn.0000092792.97122.e0] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- Patrick Maxwell
- Renal Section, Imperial College, Hammersmith Campus, London, United Kingdom.
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Willam C, Nicholls LG, Ratcliffe PJ, Pugh CW, Maxwell PH. The prolyl hydroxylase enzymes that act as oxygen sensors regulating destruction of hypoxia-inducible factor α. ACTA ACUST UNITED AC 2004; 44:75-92. [PMID: 15581484 DOI: 10.1016/j.advenzreg.2003.11.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Carsten Willam
- Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK
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Le NTV, Richardson DR. Competing pathways of iron chelation: Angiogenesis or anti-tumor activity: Targeting different molecules to induce specific effects. Int J Cancer 2004; 110:468-9. [PMID: 15095318 DOI: 10.1002/ijc.20161] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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