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Trkulja V. Treating anemia associated with chronic renal failure with erythropoiesis stimulators: recombinant human erythropoietin might be the best among the available choices. Med Hypotheses 2011; 78:157-61. [PMID: 22078846 DOI: 10.1016/j.mehy.2011.10.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 09/11/2011] [Accepted: 10/12/2011] [Indexed: 11/26/2022]
Abstract
Chronic renal failure (CRF) is a widespread medical problem commonly accompanied by a hypoproliferative anemia ("renal anemia") due to erythropoietin deficiency. Anemia greatly contributes to reduced quality of life (Hr-QoL) and high morbidity and mortality in CRF patients. Recombinant human erythropoietin (rHu-Epo) was introduced to medical practice some 20years ago. It enables correction of anemia (hemoglobin levels, Hb) with dramatic immediate (Hr-QoL improvement) and long-term effects (reduced morbidity and mortality). Newer experimental data suggest that long-term benefits could be due not only to antianemic effect, but also to a direct organoprotective effect of (rHu)-Epo mediated through a receptor complex different from the "erythropoietic" erythropoietin receptor. During the last decade, two alternative treatments for renal anemia have been approved: darbepoetin and CERA. Both are direct agonists of the "erythropoietic" receptors and both were derived from rHu-Epo. Molecularly, they differ from rHu-Epo in that they are much larger molecules (darbepoetin is genetically modified rHu-Epo with a higher sugar content and CERA is pegylated rHu-Epo) with lower affinity for the erythropoietin receptor but with a longer circulating time. In terms of renal anemia correction, they are non-inferior to rHu-Epo and allow for less frequent dosing. They have never been compared to rHu-Epo regarding the long-term outcomes. It is hypothesized that regarding the long-term outcomes (morbidity, mortality), rHu-Epo might be superior to those larger molecules. The hypothesis is based on two types of observations. First, experimental data emphasize the role of small, erythropoietically less valuable rHu-Epo isoforms in its organoprotective effects. Second, clinical observations suggest that rHu-Epo enables for less variable Hb correction than the larger molecules, and pronounced within-subject Hb variability has been suggested as an independent predictor of poor long-term outcomes of renal anemia management.
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Affiliation(s)
- Vladimir Trkulja
- Department of Pharmacology, Zagreb University School of Medicine, Šalata 11, 10000 Zagreb, Croatia.
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152
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Sølling C. Organ-protective and immunomodulatory effects of erythropoietin--an update on recent clinical trials. Basic Clin Pharmacol Toxicol 2011; 110:113-21. [PMID: 22004532 DOI: 10.1111/j.1742-7843.2011.00820.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Erythropoietin (EPO) belongs to a group of pharmacological agents with multifunctional effects. EPO was originally acknowledged as the main regulator of erythropoiesis, but it also exhibits several extra haematopoietic properties, such as promoting the maintenance of homeostasis of cells under stress. These pleiotropic effects have been extensively investigated in preclinical models including models of ischaemic-reperfusions injuries, inflammation, neuroprotection, neovascularisation and wound healing. Promising effects of EPO have especially been reported in models of ischaemic-reperfusions injuries. The mechanisms by which EPO exerts these organ-protective effects are not completely understood, although anti-apoptotic, anti-inflammatory and anti-oxidative properties have been described. Activation of the EPO receptor initiates several intracellular signalling systems, such as, phosphatidylinositol 3-kinase, STAT5, mitogen-activated protein kinase and nuclear factor-kappa B. These pathways are recognized as involved in the cellular response to stress and regulation of apoptosis. Although EPO has been demonstrated to be effective in animal models, the effect has not been clearly demonstrated in clinical trials. This MiniReview gives a brief introduction to the pleiotropic effects of EPO, the evidence of organ protection in animal models, and discusses the disappointing results obtained from recent clinical trials.
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Affiliation(s)
- Christoffer Sølling
- Department of Anaesthesiology and Intensive Care Medicine, Aarhus University Hospital, Aarhus, Denmark
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153
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Nairz M, Sonnweber T, Schroll A, Theurl I, Weiss G. The pleiotropic effects of erythropoietin in infection and inflammation. Microbes Infect 2011; 14:238-46. [PMID: 22094132 PMCID: PMC3278592 DOI: 10.1016/j.micinf.2011.10.005] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 10/18/2011] [Indexed: 01/30/2023]
Abstract
Erythropoietin (EPO) is a multi-functional cytokine, which exerts erythropoietic effects but also carries anti-apoptotic and immune-modulatory activities upon binding to two distinct receptors which are expressed on erythroid, parenchymal and immune cells, respectively. Whereas EPO ameliorates hemolytic anemia in malaria or trypanosomiasis and improves the course of autoimmune diseases such as inflammatory bowel disease or autoimmune encephalomyelitis, it deleteriously inhibits macrophage functions in Salmonella infection in animal models. Thus, the specific modulation of extra-erythropoietic EPO activity forms an attractive therapeutic target in infection and inflammation.
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Affiliation(s)
| | | | | | | | - Günter Weiss
- Corresponding author. Tel.: +43 512 504 23255; fax: +43 512 504 25607.
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154
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Mausberg AK, Meyer zu Hörste G, Dehmel T, Stettner M, Lehmann HC, Sheikh KA, Kieseier BC. Erythropoietin ameliorates rat experimental autoimmune neuritis by inducing transforming growth factor-β in macrophages. PLoS One 2011; 6:e26280. [PMID: 22043313 PMCID: PMC3197078 DOI: 10.1371/journal.pone.0026280] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 09/23/2011] [Indexed: 12/21/2022] Open
Abstract
Erythropoietin (EPO) is a pleiotropic cytokine originally identified for its role in erythropoiesis. In addition, in various preclinical models EPO exhibited protective activity against tissue injury. There is an urgent need for potent treatments of autoimmune driven disorders of the peripheral nervous system (PNS), such as the Guillain-Barré syndrome (GBS), a disabling autoimmune disease associated with relevant morbidity and mortality. To test the therapeutic potential of EPO in experimental autoimmune neuritis (EAN) - an animal model of human GBS--immunological and clinical effects were investigated in a preventive and a therapeutic paradigm. Treatment with EPO reduced clinical disease severity and if given therapeutically also shortened the recovery phase of EAN. Clinical findings were mirrored by decreased inflammation within the peripheral nerve, and myelin was well maintained in treated animals. In contrast, EPO increased the number of macrophages especially in later stages of the experimental disease phase. Furthermore, the anti-inflammatory cytokine transforming growth factor (TGF)-beta was upregulated in the treated cohorts. In vitro experiments revealed less proliferation of T cells in the presence of EPO and TGF-beta was moderately induced, while the secretion of other cytokines was almost not altered by EPO. Our data suggest that EPO revealed its beneficial properties by the induction of beneficial macrophages and the modulation of the immune system towards anti-inflammatory responses in the PNS. Further studies are warranted to elaborate the clinical usefulness of EPO for treating immune-mediated neuropathies in affected patients.
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Affiliation(s)
- Anne K. Mausberg
- Department of Neurology, Heinrich-Heine-University, Duesseldorf, Germany
| | | | - Thomas Dehmel
- Department of Neurology, Heinrich-Heine-University, Duesseldorf, Germany
| | - Mark Stettner
- Department of Neurology, Heinrich-Heine-University, Duesseldorf, Germany
| | - Helmar C. Lehmann
- Department of Neurology, Heinrich-Heine-University, Duesseldorf, Germany
| | - Kazim A. Sheikh
- Department of Neurology, University of Texas Medical School at Houston, Houston, Texas, United States of America
| | - Bernd C. Kieseier
- Department of Neurology, Heinrich-Heine-University, Duesseldorf, Germany
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155
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Isolation and characterization of renal erythropoietin-producing cells from genetically produced anemia mice. PLoS One 2011; 6:e25839. [PMID: 22022454 PMCID: PMC3191152 DOI: 10.1371/journal.pone.0025839] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 09/12/2011] [Indexed: 12/19/2022] Open
Abstract
Understanding the nature of renal erythropoietin-producing cells (REPs) remains a central challenge for elucidating the mechanisms involved in hypoxia and/or anemia-induced erythropoietin (Epo) production in adult mammals. Previous studies have shown that REPs are renal peritubular cells, but further details are lacking. Here, we describe an approach to isolate and characterize REPs. We bred mice bearing an Epo gene allele to which green fluorescent protein (GFP) reporter cDNA was knocked-in (EpoGFP) with mice bearing an Epo gene allele lacking the 3′ enhancer (EpoΔ3′E). Mice harboring the mutant EpoGFP/Δ3′E gene exhibited anemia (average Hematocrit 18% at 4 to 6 days after birth), and this perinatal anemia enabled us to identify and purify REPs based on GFP expression from the kidney. Light and confocal microscopy revealed that GFP immunostaining was confined to fibroblastic cells that reside in the peritubular interstitial space, confirming our previous observation in Epo-GFP transgenic reporter assays. Flow cytometry analyses revealed that the GFP fraction constitutes approximately 0.2% of the whole kidney cells and 63% of GFP-positive cells co-express CD73 (a marker for cortical fibroblasts and Epo-expressing cells in the kidney). Quantitative RT-PCR analyses confirmed that Epo expression was increased by approximately 100-fold in the purified population of REPs compared with that of the unsorted cells or CD73-positive fraction. Gene expression analyses showed enrichment of Hif2α and Hif3α mRNA in the purified population of REPs. The genetic approach described here provides a means to isolate a pure population of REPs, allowing the analysis of gene expression of a defined population of cells essential for Epo production in the kidney. This has provided evidence that positive regulation by HIF2α and negative regulation by HIF3α might be necessary for correct renal Epo induction. (282 words)
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Erythropoietin levels are not independently associated with malaria-attributable severe disease in Mozambican children. PLoS One 2011; 6:e24090. [PMID: 21912616 PMCID: PMC3166067 DOI: 10.1371/journal.pone.0024090] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 07/29/2011] [Indexed: 12/26/2022] Open
Abstract
Background Severe malaria is difficult to differentiate from other forms of malaria or other infections with similar symptoms. Any parameter associated to malaria-attributable severe disease could help to improve severe malaria diagnosis. Methodology This study assessed the relation between erythropoietin (EPO) and malaria-attributable severe disease in an area of Mozambique with moderate malaria transmission. 211 children <5 years, recruited at Manhiça District Hospital or in the surrounding villages, were included in one of the following groups: severe malaria (SM, n = 44), hospital malaria without severity (HM, n = 49), uncomplicated malaria (UM, n = 47), invasive bacterial infection without malaria parasites (IBI, n = 39) and healthy community controls (C, n = 32). Malaria was diagnosed by microscopy and IBI by blood/cerebrospinal fluid culture. Principal Findings Mean EPO concentration in the control group was 20.95 U/l (SD = 2.96 U/l). Values in this group were lower when compared to each of the clinical groups (p = 0.026 C versus UM, p<0.001 C vs HM, p<0.001 C vs SM and p<0.001 C vs IBI). In the 3 malaria groups, values increased with severity [mean = 40.82 U/l (SD = 4.07 U/l), 125.91 U/l (SD = 4.99U/l) and 320.87 U/l (SD = 5.91U/l) for UM, HM and SM, respectively, p<0.001]. The IBI group [mean = 101.75 U/l (SD = 4.12 U/l)] presented lower values than the SM one (p = 0.002). In spite of the differences, values overlapped between study groups and EPO levels were only associated to hemoglobin. Hemoglobin means of the clinical groups were 93.98 g/dl (SD = 14.77 g/dl) for UM, 75.96 g/dl (SD = 16.48 g/dl) for HM, 64.34 g/dl (SD = 22.99 g/dl) for SM and 75.67 g/dl (SD = 16.58 g/dl) for IBI. Conclusions Although EPO levels increase according to malaria severity and are higher in severe malaria than in bacteremia, the utility of EPO to distinguish malaria-attributable severe disease is limited due to the overlap of values between the study groups and the main role of hemoglobin in the expression of EPO.
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158
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Zhao J, Li G, Zhang Y, Su X, Hang C. The potential role of JAK2/STAT3 pathway on the anti-apoptotic effect of recombinant human erythropoietin (rhEPO) after experimental traumatic brain injury of rats. Cytokine 2011; 56:343-50. [PMID: 21843949 DOI: 10.1016/j.cyto.2011.07.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 07/09/2011] [Accepted: 07/15/2011] [Indexed: 12/11/2022]
Abstract
Previous studies indicate that administration of recombinant human erythropoietin (rhEPO) protects cortical neurons following traumatic brain injury (TBI). The mechanisms of rhEPO's neuroprotection are complex and interacting, including anti-apoptosis. Here we aim to demonstrate the role of janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway on the anti-apoptotic effect of rhEPO in Feeney free falling TBI model. Activation of JAK2/STAT3 in pericontusional cortex was analyzed among rats in Sham, TBI, TBI+rhEPO, TBI+rhEPO+AG490 groups (rhEPO: 5000 U/kg day; JAK2 inhibitor AG490: 5 mg/kg day, intraperitoneal) through Western blotting, electrophoretic mobility shift assay. Bcl-2 and Bcl-xl expression (Q-PCR, Western blotting) and cell apoptosis (TUNEL) in pericontusional cortex were also detected in each group. As a result, we found that TBI could activate JAK2 and STAT3, and increase cell apoptosis in pericontusional cortex. RhEPO enhanced the expression of p-JAK2 and p-STAT3, up-regulated the mRNA and protein levels of Bcl-2 and Bcl-xl, followed by increased cell survival. Moreover, AG490 attenuated rhEPO's neuroprotection by down-regulating rhEPO-induced activation of JAK2/STAT3, and inhibiting Bcl-2 and Bcl-xl. These results suggest the essential role of JAK2/STAT3 pathway on the anti-apoptotic benefit of post-TBI rhEPO treatment.
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Affiliation(s)
- Jinbing Zhao
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, 305 East Zhongshan Road, Jiangsu Province, Nanjing 210002, PR China
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159
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Moore EM, Bellomo R, Nichol AD. Erythropoietin as a novel brain and kidney protective agent. Anaesth Intensive Care 2011; 39:356-72. [PMID: 21675055 DOI: 10.1177/0310057x1103900306] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Erythropoietin is a 30.4 kDa glycoprotein produced by the kidney, which is mostly known for its physiological function in regulating red blood cell production in the bone marrow Accumulating evidence, however suggests that erythropoietin has additional organ protective effects, which may specifically be useful in protecting the brain and kidneys from injury. Experimental evidence suggests that these protective mechanisms are multi-factorial in nature and may include inhibition of apoptotic cell death, stimulation of cellular regeneration, inhibition of deleterious pathways and promotion of recovery. In this article we review the physiology of erythropoietin, assess previous work that supports the role of erythropoietin as a general tissue protective agent and explain the mechanisms by which it may achieve this tissue protective effect. We then focus on specific laboratory and clinical data that suggest that erythropoietin has a strong brain protective and kidney protective effect. In addition, we comment on the implications of these studies for clinicians at the bedside and for researchers designing controlled trials to further elucidate the true clinical utility of erythropoietin as a neuroprotective and nephroprotective agent. Finally, we describe EPO-TBI, a double-blinded multi-centre randomised controlled trial involving the authors that is being conducted to investigate the organ protective effects of erythropoietin on the brain, and also assesses its effect on the kidneys.
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Affiliation(s)
- E M Moore
- Department of Epidemiology and Preventive Medicine, Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne, Victoria, Australia
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160
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Specific contribution of the erythropoietin gene 3' enhancer to hepatic erythropoiesis after late embryonic stages. Mol Cell Biol 2011; 31:3896-905. [PMID: 21746884 DOI: 10.1128/mcb.05463-11] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Erythropoietin (Epo) is secreted from the liver and kidney, where Epo production is strictly regulated at the transcriptional level in a hypoxia- and/or anemia-inducible manner. Here, we examined the in vivo function of the enhancer located 3' to the Epo gene (EpoE-3'). Reporter transgenic-mouse analyses revealed that the EpoE-3' enhancer is necessary and sufficient for the liver-specific and hypoxia-responsive expression of the gene after embryonic day 14.5 (E14.5). However, the enhancer is dispensable for Epo gene expression in the kidney and early-stage embryonic liver. Genetic removal of EpoE-3' from the endogenous Epo gene resulted in mice with severe anemia at late embryonic and neonatal stages due to defects in hepatic erythropoiesis, but early hepatic and splenic erythropoiesis was not affected. The mutant mice recover from the anemia in the juvenile period when major Epo production switches from the liver to the kidney. These results demonstrate that EpoE-3' is necessary for late hepatic erythropoiesis by specifically supporting paracrine production of Epo in the liver. In contrast, Epo production in the kidney utilizes distinct regulatory machinery and supports erythropoiesis in the bone marrow and spleen in adult animals.
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161
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Debevec T, Keramidas ME, Norman B, Gustafsson T, Eiken O, Mekjavic IB. Acute short-term hyperoxia followed by mild hypoxia does not increase EPO production: resolving the "normobaric oxygen paradox". Eur J Appl Physiol 2011; 112:1059-65. [PMID: 21735214 DOI: 10.1007/s00421-011-2060-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 06/22/2011] [Indexed: 12/13/2022]
Abstract
Recent findings suggest that besides renal tissue hypoxia, relative decrements in tissue oxygenation, using a transition of the breathing mixture from hyperoxic to normoxic, can also stimulate erythropoietin (EPO) production. To further clarify the importance of the relative change in tissue oxygenation on plasma EPO concentration [EPO], we investigated the effect of a consecutive hyperoxic and hypoxic breathing intervention. Eighteen healthy male subjects were assigned to either IHH (N = 10) or CON (N = 8) group. The IHH group breathed pure oxygen (F(i)O(2) ~ 1.0) for 1 h, followed by a 1-h period of breathing a hypoxic gas mixture (F(i)O(2) ~ 0.15). The CON group breathed a normoxic gas mixture (F(i)O(2) ~ 0.21) for the same duration (2 h). Blood samples were taken just before, after 60 min, and immediately after the 2-h exposure period. Thereafter, samples were taken at 3, 5, 8, 24, 32, and 48 h after the exposure. During the breathing interventions, subjects remained in supine position. There were significant increases in absolute [EPO] within groups at 8 and 32 h in the CON and at 32 h only in the IHH group. No significant differences in absolute [EPO] were observed between groups following the intervention. Relative (∆[EPO]) levels were significantly lower in the IHH than in the CON group, 5 and 8 h following exposure. The tested protocol of consecutive hyperoxic-hypoxic gas mixture breathing did not induce [EPO] synthesis stimulation. Moreover, the transient attenuation in ∆[EPO] in the IHH group was most likely due to a hyperoxic suppression. Hence, our findings provide further evidence against the "normobaric O(2) paradox" theory.
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Affiliation(s)
- Tadej Debevec
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
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162
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Grau-Amorós J, Formiga F, Urrutia A. Anemia en la insuficiencia cardiaca crónica. Rev Clin Esp 2011; 211:354-9. [DOI: 10.1016/j.rce.2011.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 03/23/2011] [Accepted: 03/27/2011] [Indexed: 10/18/2022]
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163
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Pérès EA, Valable S, Guillamo JS, Marteau L, Bernaudin JF, Roussel S, Lechapt-Zalcman E, Bernaudin M, Petit E. Targeting the erythropoietin receptor on glioma cells reduces tumour growth. Exp Cell Res 2011; 317:2321-32. [PMID: 21749867 DOI: 10.1016/j.yexcr.2011.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 06/21/2011] [Accepted: 06/21/2011] [Indexed: 12/15/2022]
Abstract
Hypoxia has been shown to be one of the major events involved in EPO expression. Accordingly, EPO might be expressed by cerebral neoplastic cells, especially in glioblastoma, known to be highly hypoxic tumours. The expression of EPOR has been described in glioma cells. However, data from the literature remain descriptive and controversial. On the basis of an endogenous source of EPO in the brain, we have focused on a potential role of EPOR in brain tumour growth. In the present study, with complementary approaches to target EPO/EPOR signalling, we demonstrate the presence of a functional EPO/EPOR system on glioma cells leading to the activation of the ERK pathway. This EPO/EPOR system is involved in glioma cell proliferation in vitro. In vivo, we show that the down-regulation of EPOR expression on glioma cells reduces tumour growth and enhances animal survival. Our results support the hypothesis that EPOR signalling in tumour cells is involved in the control of glioma growth.
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Affiliation(s)
- Elodie A Pérès
- CERVOxy team Hypoxia and cerebrovascular pathophysiology, UMR 6232 CI-NAPS, Université de Caen Basse-Normandie, Université Paris-Descartes, Caen, France
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164
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Rocha S, Costa E, Rocha-Pereira P, Ferreira F, Cleto E, Barbot J, Quintanilha A, Belo L, Santos-Silva A. Erythropoiesis versus inflammation in Hereditary Spherocytosis clinical outcome. Clin Biochem 2011; 44:1137-1143. [PMID: 21704613 DOI: 10.1016/j.clinbiochem.2011.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 05/30/2011] [Accepted: 06/05/2011] [Indexed: 11/18/2022]
Abstract
OBJECTIVES This study aimed to evaluate the relationship between erythropoiesis and inflammation, in Hereditary Spherocytosis (HS) clinical outcome. DESIGN AND METHODS We studied 26 controls and 82 HS patients presenting mild (n = 49) and severer (n = 33) HS forms. We evaluated plasma levels of EPO, sTfR, ferritin, iron, folic acid, vitamin B12, TNF-α, IFN-γ, elastase and lactoferrin; leukocyte and reticulocyte counts and RPI were determined. RESULTS All HS patients showed significantly higher EPO, sTfR, reticulocytes and RPI but only mild HS presented normal hemoglobin levels; the positive significant correlations between EPO and sTfR, reticulocytes and RPI observed in mild HS were not observed in severer HS patients. HS patients presented with higher levels of neutrophils, TNF-α, IFN-γ, elastase, lactoferrin and ferritin. CONCLUSIONS Our data show HS as a disease linked to enhanced erythropoiesis that is disturbed in the more severe forms, to which inflammation may contribute, at least in part.
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Affiliation(s)
- Susana Rocha
- Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4050-047, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal.
| | - Elísio Costa
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal; Instituto de Ciências da Saúde, Universidade Católica Portuguesa, Campus da Asprela, Rua Dr. António Bernardino Almeida, 4200-072, Porto, Portugal.
| | - Petronila Rocha-Pereira
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal; Centro de Investigação em Ciências da Saúde (CICS), Universidade da Beira Interior, Av. Infante D. Henrique, 6201-506, Covilhã, Portugal.
| | - Fátima Ferreira
- Serviço de Hematologia Clínica, Hospital S. João, Alameda Prof. Hernâni Monteiro, 4200-319, Porto, Portugal.
| | - Esmeralda Cleto
- Sector de Hematologia Pediátrica, Centro Hospitalar do Porto (CHP) - Hospital Santo António, Largo Prof. Abel Salazar, 4099-001, Porto, Portugal.
| | - José Barbot
- Serviço de Hematologia, Centro Hospitalar do Porto (CHP) - Hospital Maria Pia, Largo Prof. Abel Salazar, 4099-001, Porto, Portugal.
| | - Alexandre Quintanilha
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Largo Prof. Abel Salazar, 2, 4099-003, Porto, Portugal.
| | - Luís Belo
- Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4050-047, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal.
| | - Alice Santos-Silva
- Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4050-047, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal.
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Abstract
BACKGROUND Erythropoietin (EPO) is an oxygenregulated hormone promoting the differentiation of erythroid progenitor cells. Apart fromhypoxia, few data is available about release by secretagogues including hormones. AIM To investigate EPO serum concentration in subjects with endocrine diseases. MATERIAL AND METHODS A retrospective study evaluating serumEPO concentrations in serumleftovers fromsubjects with various endocrine disorders. RESULTS EPO is not noticeably influenced by thyroid hormone or cortisol concentrations and the relationship with hemoglobin concentration is preserved. In acromegalic patients, the latter is lost but EPO is neither statistically influenced by GH/IGF-I. This may reflect a dual action of GH and/or IGF-I on erythroid progenitors proliferation as well as on EPO synthesis. CONCLUSION EPO is not noticeably modified by endocrine disorders although GH and or IGF-I may alter EPO relationship with blood hemoglobin concentration.
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Affiliation(s)
- E Klein
- Department of Nuclear Medicine, University Hospital of Bordeaux, Bordeaux, France
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166
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Lee FS, Percy MJ. The HIF pathway and erythrocytosis. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2011; 6:165-92. [PMID: 20939709 DOI: 10.1146/annurev-pathol-011110-130321] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Because of the central role that red blood cells play in the delivery of oxygen to tissues of the body, red blood cell mass must be controlled at precise levels. The glycoprotein hormone erythropoietin (EPO) regulates red blood cell mass. EPO transcription, in turn, is regulated by a distinctive oxygen-sensing mechanism. In this pathway, prolyl hydroxylase domain protein (PHD) site-specifically hydroxylates the α-subunit of the transcription factor hypoxia-inducible factor α (HIF-α), thereby targeting the latter for degradation by the von Hippel-Lindau tumor-suppressor protein (VHL). Under hypoxic conditions, this posttranslational modification of HIF-α is inhibited, which stabilizes it and promotes the transcriptional activation of genes, including that for EPO. Rare patients with erythrocytosis have mutations in the genes encoding for PHD2, HIF-2α, and VHL, which implicates these proteins as critical to the proper control of red blood cell mass in humans.
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Affiliation(s)
- Frank S Lee
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.
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167
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Cobalt uptake and binding in human red blood cells. Blood Cells Mol Dis 2011; 46:266-76. [DOI: 10.1016/j.bcmd.2011.02.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 02/15/2011] [Indexed: 11/23/2022]
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168
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Tauman R, Many A, Deutsch V, Arvas S, Ascher-Landsberg J, Greenfeld M, Sivan Y. Maternal snoring during pregnancy is associated with enhanced fetal erythropoiesis--a preliminary study. Sleep Med 2011; 12:518-22. [PMID: 21440495 DOI: 10.1016/j.sleep.2010.09.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/17/2010] [Accepted: 09/06/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE AND BACKGROUND Snoring is common among pregnant women and early reports suggest that it may bear a risk to the fetus. Increased fetal erythropoiesis manifested by elevated circulating nucleated red blood cells (nRBCs) has been found in complicated pregnancies involving fetal hypoxia. Both erythropoietin (EPO) and interleukin-6 (IL-6) mediate elevation of circulating nRBCs. The intermittent hypoxia and systemic inflammation elicited by sleep-disordered breathing (SDB) could affect fetal erythropoiesis during pregnancy. We hypothesized that maternal snoring will result in increased levels of fetal circulating nRBCs via increased concentrations of EPO, IL-6, or both. METHODS Women of singleton uncomplicated full-term pregnancies were recruited during labor and completed a designated questionnaire. Umbilical cord blood was collected immediately after birth and analyzed for nRBCs, plasma EPO and plasma IL-6 concentrations. Newborn data were retrieved from medical records. RESULTS One hundred and twenty-two women were recruited. Thirty-nine percent of women reported habitual snoring during pregnancy. Cord blood levels of circulating nRBCs, EPO and IL-6 were significantly elevated in habitual snorers compared with non-snorers (p = 0.03, 0.005 and 0.01; respectively). No differences in maternal characteristics or newborn crude outcomes were found. CONCLUSIONS Maternal snoring during pregnancy is associated with enhanced fetal erythropoiesis manifested by increased cord blood levels of nRBCs, EPO and IL-6. This provides preliminary evidence that maternal snoring is associated with subtle alterations in markers of fetal well being.
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Affiliation(s)
- Riva Tauman
- Pediatric Sleep Center, Dana Children's Hospital, Tel Aviv Souraski Medical Center, Tel Aviv University, Tel Aviv, Israel
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169
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Moore E, Bellomo R. Erythropoietin (EPO) in acute kidney injury. Ann Intensive Care 2011; 1:3. [PMID: 21906325 PMCID: PMC3159901 DOI: 10.1186/2110-5820-1-3] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 03/21/2011] [Indexed: 02/05/2023] Open
Abstract
Erythropoietin (EPO) is a 30.4 kDa glycoprotein produced by the kidney, and is mostly well-known for its physiological function in regulating red blood cell production in the bone marrow. Accumulating evidence, however, suggests that EPO has additional organ protective effects, which may be useful in the prevention or treatment of acute kidney injury. These protective mechanisms are multifactorial in nature and include inhibition of apoptotic cell death, stimulation of cellular regeneration, inhibition of deleterious pathways, and promotion of recovery. In this article, we review the physiology of EPO, assess previous work that supports the role of EPO as a general tissue protective agent, and explain the mechanisms by which it may achieve this tissue protective effect. We then focus on experimental and clinical data that suggest that EPO has a kidney protective effect.
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Affiliation(s)
- Elizabeth Moore
- Australian and New Zealand Intensive Care Research Centre, Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, VIC 3004, Australia.
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170
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An extra high dose of erythropoietin fails to support the proliferation of erythropoietin dependent cell lines. Cytotechnology 2011; 63:101-9. [PMID: 21380566 DOI: 10.1007/s10616-011-9345-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2007] [Accepted: 10/05/2007] [Indexed: 10/18/2022] Open
Abstract
Erythropoietin is responsible for the red blood cell formation by stimulating the proliferation and the differentiation of erythroid precursor cells. Erythropoietin triggers the conformational change in its receptor thereby induces the phosphorylation of JAK2. In this study, we show that an extra high dose of erythropoietin, however, fails to activate the erythropoietin receptor, to stimulate the phosphorylation of JAK2 and to support the cell proliferation of Ep-FDC-P2 cell. Moreover, high dose of EPO also inhibited the proliferation of various erythropoietin-dependent cell lines, suggesting that excess amount of EPO could not trigger the conformational change of the receptor. In the presence of an extra high dose of erythropoietin as well as in the absence of erythropoietin, the cells caused the DNA fragmentation, a typical symptom of apoptosis. The impairment of cell growth and the DNA fragmentation at the extremely high concentration of EPO was rescued by the addition of erythropoietin antibody or soluble form of erythropoietin receptor by titrating the excess erythropoietin. These results suggest that two erythropoietin binding sites on erythropoietin receptor dimer should be occupied by a single erythropoietin molecule for the proper conformational change of the receptor and the signal transduction of erythropoietin, instead, when two erythropoietin binding sites on the receptor are shared by two erythropoietin molecules, it fails to evoke the conformational change of erythropoietin receptor adequate for signal transduction.
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171
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Nairz M, Schroll A, Moschen AR, Sonnweber T, Theurl M, Theurl I, Taub N, Jamnig C, Neurauter D, Huber LA, Tilg H, Moser PL, Weiss G. Erythropoietin contrastingly affects bacterial infection and experimental colitis by inhibiting nuclear factor-κB-inducible immune pathways. Immunity 2011; 34:61-74. [PMID: 21256055 PMCID: PMC3032045 DOI: 10.1016/j.immuni.2011.01.002] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 10/29/2010] [Accepted: 01/05/2011] [Indexed: 01/17/2023]
Abstract
Erythropoietin (EPO) is the principal cytokine regulating erythropoiesis through its receptor, EPOR. Interestingly, EPORs are also found on immune cells with incompletely understood functions. Here, we show that EPO inhibits the induction of proinflammatory genes including tumor necrosis factor (TNF)-α and inducible nitric oxide (NO) synthase in activated macrophages, which is mechanistically attributable to blockage of nuclear factor (NF)-κB p65 activation by EPO. Accordingly, in systemic Salmonella infection, treatment of mice with EPO results in reduced survival and impaired pathogen clearance because of diminished formation of anti-microbial effector molecules such as TNF-α and NO. However, neutralization of endogenous EPO or genetic ablation of Epor promotes Salmonella elimination. In contrast, in chemically induced colitis, EPO-EPOR interaction decreases the production of NF-κB-inducible immune mediators, thus limiting tissue damage and ameliorating disease severity. These immune-modulatory effects of EPO may be of therapeutic relevance in infectious and inflammatory diseases.
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Affiliation(s)
- Manfred Nairz
- Department of Internal Medicine I, Clinical Immunology and Infectious Diseases, Innsbruck Medical University, 6020 Innsbruck, Austria
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172
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Segura J, Zorzoli M. Distinction Between Endogenous and Exogenous Erythropoietin: Marker Methods. HORMONE USE AND ABUSE BY ATHLETES 2011. [DOI: 10.1007/978-1-4419-7014-5_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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173
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Genc S, Zadeoglulari Z, Oner MG, Genc K, Digicaylioglu M. Intranasal erythropoietin therapy in nervous system disorders. Expert Opin Drug Deliv 2010; 8:19-32. [DOI: 10.1517/17425247.2011.540236] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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174
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Sallmon H, Gutti RK, Ferrer-Marin F, Liu ZJ, Sola-Visner MC. Increasing platelets without transfusion: is it time to introduce novel thrombopoietic agents in neonatal care? J Perinatol 2010; 30:765-9. [PMID: 20410910 DOI: 10.1038/jp.2010.50] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Food and Drug Administration recently approved two novel thrombopoiesis-stimulating agents, Romiplostim (AMG-531, Nplate) and Eltrombopag (Promacta), for the treatment of adults with immune thrombocytopenic purpura. For physicians taking care of critically ill neonates, this offers the opportunity of decreasing platelet transfusions and potentially improving the outcomes of neonates with severe and prolonged thrombocytopenia. However, several developmental factors need to be taken into consideration. First, the population of thrombocytopenic neonates likely to benefit from these agents needs to be carefully selected. Second, the mechanisms underlying neonatal and adult thrombocytopenia differ from each other and are incompletely understood, and pre-clinical evidence suggests that the response of neonates to thrombopoietic factors might be different from that of adults. Finally, the potential non-hematopoietic effects of thrombopoietin have not been well established. Here, we will discuss these issues in detail, and will highlight the critical developmental differences between neonates and adults that need to be considered as we think about introducing these agents into neonatal care.
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Affiliation(s)
- H Sallmon
- Division of Newborn Medicine, Children's Hospital Boston and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
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175
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Goetghebeur PJD, Lerdrup L, Sylvest A, Dias R. Erythropoietin reverses the attentional set-shifting impairment in a rodent schizophrenia disease-like model. Psychopharmacology (Berl) 2010; 212:635-42. [PMID: 20734030 DOI: 10.1007/s00213-010-1990-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 08/04/2010] [Indexed: 12/11/2022]
Abstract
RATIONALE Executive function impairment, as classically assessed using the Wisconsin Card Sort Test or intradimensional/extradimensional tests, is a key feature of schizophrenia but remains inadequately treated by existing therapies. Recently, however, erythropoietin has been shown to improve attentional set-shifting performance in schizophrenic patients. OBJECTIVE The present study utilized the rat intradimensional/extradimensional task to investigate the potential of erythropoietin to reverse a phencyclidine-induced extradimensional shift impairment when given alone or in combination with subchronic haloperidol treatment. METHODS Rats were subjected to a subchronic systemic administration (7 days, b.i.d) of either saline vehicle or phencyclidine (5 mg/kg) followed by a 7-day washout period during which haloperidol was given. Subsequently, rats were trained to dig in baited bowls for a food reward and to discriminate on the basis of digging media or bowl odor. In experiment 1, rats performed a series of discriminations following acute administration of vehicle, erythropoietin, or modafinil. In a second experiment, rats receiving either haloperidol in the drinking water or just normal drinking water were run in the attentional set-shifting task after acute administration of erythropoietin (1,000 or 10,000 IU/ml i.p., selected from experiment 1). RESULTS The subchronic phencyclidine-induced extradimensional deficit was ameliorated by both erythropoietin and modafinil. When combined with subchronic haloperidol, the higher dose of erythropoietin tested was able to reverse the extradimensional shift impairment. CONCLUSIONS Overall, these findings further support the use of erythropoietin as an adjunct to antipsychotic therapy in order to address, at least part of, the cognitive dysfunction associated with schizophrenia.
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176
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Sargin D, Friedrichs H, El-Kordi A, Ehrenreich H. Erythropoietin as neuroprotective and neuroregenerative treatment strategy: comprehensive overview of 12 years of preclinical and clinical research. Best Pract Res Clin Anaesthesiol 2010; 24:573-94. [PMID: 21619868 DOI: 10.1016/j.bpa.2010.10.005] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 10/11/2010] [Indexed: 12/13/2022]
Abstract
Erythropoietin (EPO), originally discovered as hematopoietic growth factor, has direct effects on cells of the nervous system that make it a highly attractive candidate drug for neuroprotection/neuroregeneration. Hardly any other compound has led to so much preclinical work in the field of translational neuroscience than EPO. Almost all of the >180 preclinical studies performed by many independent research groups from all over the world in the last 12 years have yielded positive results on EPO as a neuroprotective drug. The fact that EPO was approved for the treatment of anemia >20 years ago and found to be well tolerated and safe, facilitated the first steps of translation from preclinical findings to the clinic. On the other hand, the same fact, naturally associated with loss of patent protection, hindered to develop EPO as a highly promising therapeutic strategy for application in human brain disease. Therefore, only few clinical neuroprotection studies have been concluded, all with essentially positive and stimulating results, but no further development towards the clinic has occurred thus far. This article reviews the preclinical and clinical work on EPO for the indications neuroprotection/neuroregeneration and cognition, and hopefully will stimulate new endeavours promoting development of EPO for the treatment of human brain diseases.
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Affiliation(s)
- Derya Sargin
- Division of Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Hermann-Rein Str. 3, 37075 Göttingen, Germany
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177
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Abstract
The hormone erythropoietin (Epo) maintains red blood cell mass by promoting the survival, proliferation and differentiation of erythrocytic progenitors. Circulating Epo originates mainly from fibroblasts in the renal cortex. Epo production is controlled at the transcriptional level. Hypoxia attenuates the inhibition of the Epo promoter by GATA-2. More importantly, hypoxia promotes the availability of heterodimeric (α/β) hypoxia-inducible transcription factors (predominantly HIF-2) which stimulate the Epo enhancer. The HIFs are inactivated in normoxia by enzymatic hydroxylation of their α-subunits. Three HIF-α prolyl hydroxylases (PHD-1, -2 and -3) initiate proteasomal degradation of HIF-α, while an asparaginyl hydroxylase ('factor inhibiting HIF-1', FIH-1) inhibits the transactivation potential. The HIF-α hydroxylases contain Fe(2+) and require 2-oxoglutarate as co-factor. The in vivo response is dynamic, i.e. the concentration of circulating Epo increases initially greatly following an anaemic or hypoxaemic stimulus and then declines despite continued hypoxia. Epo and angiotensin II collaborate in the maintenance of the blood volume. Whether extra-renal sites (brain, skin) modulate renal Epo production is a matter of debate. Epo overproduction results in erythrocytosis. Epo deficiency is the primary cause of the anaemia in chronic kidney disease and a contributing factor in the anaemias of chronic inflammation and cancer. Here, recombinant analogues can substitute for the hormone.
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Affiliation(s)
- Wolfgang Jelkmann
- Institute of Physiology, University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany.
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178
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Ikeda Y, Taveira-DaSilva AM, Pacheco-Rodriguez G, Steagall WK, El-Chemaly S, Gochuico BR, May RM, Hathaway OM, Li S, Wang JA, Darling TN, Stylianou M, Moss J. Erythropoietin-driven proliferation of cells with mutations in the tumor suppressor gene TSC2. Am J Physiol Lung Cell Mol Physiol 2010; 300:L64-72. [PMID: 21036916 DOI: 10.1152/ajplung.00095.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lymphangioleiomyomatosis (LAM) is characterized by cystic lung destruction, resulting from proliferation of smooth-muscle-like cells, which have mutations in the tumor suppressor genes TSC1 or TSC2. Among 277 LAM patients, severe disease was associated with hypoxia and elevated red blood cell indexes that accompanied reduced pulmonary function. Because high red cell indexes could result from hypoxemia-induced erythropoietin (EPO) production, and EPO is a smooth muscle cell mitogen, we investigated effects of EPO in human cells with genetic loss of tuberin function, and we found that EPO increased proliferation of human TSC2-/-, but not of TSC2+/-, cells. A discrete population of cells grown from explanted lungs was characterized by the presence of EPO receptor and loss of heterozygosity for TSC2, consistent with EPO involvement. In LAM cells from lung nodules, EPO was localized to the extracellular matrix, supporting evidence for activation of an EPO-driven signaling pathway. Although the high red cell mass of LAM patients could be related to advanced disease, we propose that EPO, synthesized in response to episodic hypoxia, may increase disease progression by enhancing the proliferation of LAM cells.
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Affiliation(s)
- Yoshihiko Ikeda
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1590, USA
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179
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Zeigler BM, Vajdos J, Qin W, Loverro L, Niss K. A mouse model for an erythropoietin-deficiency anemia. Dis Model Mech 2010; 3:763-72. [PMID: 20959632 DOI: 10.1242/dmm.004788] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In mammals, the production of red blood cells is tightly regulated by the growth factor erythropoietin (EPO). Mice lacking a functional Epo gene are embryonic lethal, and studying erythropoiesis in EPO-deficient adult animals has therefore been limited. In order to obtain a preclinical model for an EPO-deficient anemia, we developed a mouse in which Epo can be silenced by Cre recombinase. After induction of Cre activity, Epo(KO/flox) mice experience a significant reduction of serum EPO levels and consequently develop a chronic, normocytic and normochromic anemia. Furthermore, compared with wild-type mice, Epo expression in Epo(KO/flox) mice is dramatically reduced in the kidney, and expression of a well-known target gene of EPO signaling, Bcl2l1, is reduced in the bone marrow. These observations are similar to the clinical display of anemia in patients with chronic kidney disease. In addition, during stress-induced erythropoiesis these mice display the same recovery rate as their heterozygous counterparts. Taken together, these results demonstrate that this model can serve as a valuable preclinical model for the anemia of EPO deficiency, as well as a tool for the study of stress-induced erythropoiesis during limiting conditions of EPO.
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Affiliation(s)
- Brandon M Zeigler
- Department of Inflammation, Pfizer Global Research and Development, 700 West Chesterfield Parkway, St Louis, MO 63017, USA
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180
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Guan F, Uboh CE, Soma LR, Maylin G, Jiang Z, Chen J. Confirmatory Analysis of Continuous Erythropoietin Receptor Activator and Erythropoietin Analogues in Equine Plasma by LC−MS for Doping Control. Anal Chem 2010; 82:9074-81. [PMID: 20945883 DOI: 10.1021/ac102031w] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Fuyu Guan
- School of Veterinary Medicine, University of Pennsylvania, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, United States, Pennsylvania Equine Toxicology and Research Center, West Chester University, West Chester, Pennsylvania 19382, United States, and Equine Drug Testing and Research Program, College of Veterinary Medicine, Cornell University, 925 Warren Drive, Ithaca, New York 14850, United States
| | - Cornelius E. Uboh
- School of Veterinary Medicine, University of Pennsylvania, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, United States, Pennsylvania Equine Toxicology and Research Center, West Chester University, West Chester, Pennsylvania 19382, United States, and Equine Drug Testing and Research Program, College of Veterinary Medicine, Cornell University, 925 Warren Drive, Ithaca, New York 14850, United States
| | - Lawrence R. Soma
- School of Veterinary Medicine, University of Pennsylvania, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, United States, Pennsylvania Equine Toxicology and Research Center, West Chester University, West Chester, Pennsylvania 19382, United States, and Equine Drug Testing and Research Program, College of Veterinary Medicine, Cornell University, 925 Warren Drive, Ithaca, New York 14850, United States
| | - George Maylin
- School of Veterinary Medicine, University of Pennsylvania, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, United States, Pennsylvania Equine Toxicology and Research Center, West Chester University, West Chester, Pennsylvania 19382, United States, and Equine Drug Testing and Research Program, College of Veterinary Medicine, Cornell University, 925 Warren Drive, Ithaca, New York 14850, United States
| | - Zibin Jiang
- School of Veterinary Medicine, University of Pennsylvania, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, United States, Pennsylvania Equine Toxicology and Research Center, West Chester University, West Chester, Pennsylvania 19382, United States, and Equine Drug Testing and Research Program, College of Veterinary Medicine, Cornell University, 925 Warren Drive, Ithaca, New York 14850, United States
| | - Jinwen Chen
- School of Veterinary Medicine, University of Pennsylvania, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, United States, Pennsylvania Equine Toxicology and Research Center, West Chester University, West Chester, Pennsylvania 19382, United States, and Equine Drug Testing and Research Program, College of Veterinary Medicine, Cornell University, 925 Warren Drive, Ithaca, New York 14850, United States
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181
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Strobach S, Kunert R, Stadlmann J, Messner P, Sevcsik E, Lhota G, Katinger H, Vorauer-Uhl K. Topological transformation of liposomes by a membrane-affecting domain of recombinant human erythropoietin. J Liposome Res 2010; 20:24-30. [PMID: 19522661 DOI: 10.3109/08982100903015033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Recombinant human erythropoietin (rh-Epo) is well accepted as a hematopoietic drug, but many other pleiotropic properties are currently under investigation. Rh-Epo-induced receptor-mediated signal transductions are accompanied with membrane dynamic processes, which facilitate the activation of individual pathways. However, its direct effect on membrane dynamics is still unknown. In the present study, we have proven the capability of rh-Epo to associate to and transform artificial lipid membranes. Association studies using neutral, negatively, and positively charged liposomes with the native as well as modified rh-Epo were performed and analyzed by transmission electron microscopy and differential scanning calorimetry. By these studies, we demonstrated that rh-Epo has the capability to transform negatively charged unilamellar vesicles into so-called disc-like micelles. Rh-Epo association to the negatively charged head groups via lysine and arginine initiates this transformation. At physiological temperatures, conformational changes within the rh-Epo structure expose a defined amino-acid sequence, which is able to induce the formation of discoid membrane structures. Enzymatic digestion, analysis, and isolation of related peptides by rp-HPLC and characterization by MS/MS enabled the identification of the membrane-affecting domain of rh-Epo (MAD-E) that represents the exposed helix B of rh-Epo. Finally, association studies performed with these peptides confirmed that the MAD-E is responsible for the formation of disc-like micelles. Since this helix B of rh-Epo has recently been supposed to be involved in the activation of neuroprotective pathways, we believe that the membrane-transforming capacity of rh-Epo participates in the proliferative activity of rh-Epo.
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Affiliation(s)
- Stefanie Strobach
- Department of Biotechnology, University of Natural Resources and Applied Life Sciences, Vienna, Austria.
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182
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Jelkmann W. Biosimilar epoetins and other "follow-on" biologics: update on the European experiences. Am J Hematol 2010; 85:771-80. [PMID: 20706990 DOI: 10.1002/ajh.21805] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
After the patents of biopharmaceuticals have expired, based on specific regulatory approval pathways copied products ("biosimilars" or "follow-on biologics") have been launched in the EU. This article summarizes experiences with hematopoietic medicines, namely the epoetins (two biosimilars traded under five different brand names) and the filgrastims (two biosimilars, six brand names). Physicians and pharmacists should be familiar with the legal and pharmacological specialities of biosimilars: The production process can differ from that of the original, clinical indications can be extrapolated, glycoproteins contain varying isoforms, the formulation may differ from the original, and biopharmaceuticals are potentially immunogenic. Only on proof of quality, efficacy and safety, biosimilars are a viable option because of their lower costs.
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Affiliation(s)
- Wolfgang Jelkmann
- Institute of Physiology, University of Luebeck, Ratzeburger Allee 160, Luebeck, Germany.
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183
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Cellular and molecular mechanisms regulating the hepatic erythropoietin expression during acute-phase response: a role for IL-6. J Transl Med 2010; 90:1306-24. [PMID: 20458283 DOI: 10.1038/labinvest.2010.85] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The source of circulating erythropoietin (EPO), the mediators and the mechanisms involved in the upregulation of EPO gene expression during acute-phase reaction are still poorly understood. Acute-phase reaction was induced by either intramuscular turpentine oil (TO) or intraperitoneal lipopolysaccharide (LPS) administration into wild-type and interleukin (IL)-6 knockout (KO) mice. Animals were killed at different time points and blood, liver and muscle tissue were collected. Serum levels of EPO were measured by enzyme-linked immunoadsorbent assay; liver and injured muscle samples were processed for RNA isolation and for protein analysis. EPO, hypoxia-inducible factors 1alpha and 2alpha (HIF-1alpha and HIF-2alpha) mRNA were analyzed by RT-PCR and the protein levels were analyzed by western blot and electrophoretic mobility shift assay. HIF-1alpha and HIF-2alpha localization was performed through immunofluorescence staining. EPO, HIF-1 and HIF-2 gene and protein expression levels were also analyzed in isolated mouse hepatocytes after stimulation with IL-6. In the wild-type animals, EPO serum levels increased dramatically at 12 h after the insults together with the hepatic gene expression. In TO-treated animals, the EPO gene expression reached an 8.2-fold increase at 12 h, and in LPS-treated mice a similar induction was recorded at 6 h (about 4.5-fold increase). In the IL-6KO strain, the upregulation after the inflammatory stimuli was much lower (only 2.0-fold increase). A progressive upregulation of HIF-1alpha and HIF-2alpha was detectable until 6 h after the insults, but only HIF-1alpha upregulation was reduced in IL-6KO mice. In isolated hepatocytes, stimulation with a single dose of IL-6 induced a nuclear accumulation of HIF-1alpha, in parallel with an increase of EPO mRNA. No effect on HIF-2alpha expression was found. IL-6 appears to be the main regulator of EPO gene expression and a major contributor for HIF-1alpha induction in hepatocytes and Kupffer cells during acute-phase response. The increase of HIF-2alpha, predominantly expressed in endothelial cells and fibroblast-like cells, seems not to be affected by the lack of IL-6.
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184
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Bailly-Chouriberry L, Noguier F, Manchon L, Piquemal D, Garcia P, Popot MA, Bonnaire Y. Blood cells RNA biomarkers as a first long-term detection strategy for EPO abuse in horseracing. Drug Test Anal 2010; 2:339-45. [DOI: 10.1002/dta.146] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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185
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Abstract
This review describes some of the physiological effects of recombinant human erythropoietin (EPO) in healthy humans. At the blood level EPO increases the arterial O(2) content not only by increasing red blood cell volume, but also by an equally important decrease in plasma volume. Well before that, EPO causes a prompt decrease in plasma levels of renin and aldosterone. Renal clearance studies suggest that EPO decreases renal proximal tubular reabsorption rate leading to activation of the tubuloglomerular feedback mechanism and a fall in glomerular filtration rate. Thus, treatment with EPO may result in suppression of endogenous EPO production through a decrease in intrarenal oxygen consumption. EPO elevates the arterial blood pressure even in healthy subjects. The receptor for EPO is present in many tissues. However, the functional effects of EPO in the skeletal muscle seem limited, and although it has been speculated that non-erythropoietic effects of EPO (angiogenesis, shift in muscle fibre types, cognitive effects) may be responsible for the increase in exercise performance, this has not been confirmed. EPO-induced haemodynamic effects call for careful monitoring during the administration period. The metabolic, hormonal and renal effects of EPO do not seem to range beyond physiologically acceptable limits and are reversible. Taken together, EPO seems safe to use for experimental purposes in healthy volunteers.
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Affiliation(s)
- Carsten Lundby
- Center for Integrative Human Physiology, University of Zurich, Institute of Physiology, Room 23 H 6, Winterthurerstr. 190, 8057 Zürich, Switzerland.
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186
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Erythropoiesis and iron sulfur cluster biogenesis. Adv Hematol 2010; 2010. [PMID: 20862391 PMCID: PMC2939393 DOI: 10.1155/2010/329394] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 06/04/2010] [Accepted: 08/02/2010] [Indexed: 11/22/2022] Open
Abstract
Erythropoiesis in animals is a synchronized process of erythroid cell differentiation that depends on successful acquisition of iron. Heme synthesis depends on iron through its dependence on iron sulfur (Fe-S) cluster biogenesis. Here, we review the relationship between Fe-S biogenesis and heme synthesis in erythropoiesis, with emphasis on the proteins, GLRX5, ABCB7, ISCA, and C1orf69. These Fe-S biosynthesis proteins are highly expressed in erythroid tissues, and deficiency of each of these proteins has been shown to cause anemia in zebrafish model. GLRX5 is involved in the production and ABCB7 in the export of an unknown factor that may function as a gauge of mitochondrial iron status, which may indirectly modulate activity of iron regulatory proteins (IRPs). ALAS2, the enzyme catalyzing the first step in heme synthesis, is translationally controlled by IRPs. GLRX5 may also provide Fe-S cofactor for ferrochelatase, the last enzyme in heme synthesis. ISCA and C1orf69 are thought to assemble Fe-S clusters for mitochondrial aconitase and for lipoate synthase, the enzyme producing lipoate for pyruvate dehydrogenase complex (PDC). PDC and aconitase are involved in the production of succinyl-CoA, a substrate for heme biosynthesis. Thus, many steps of heme synthesis depend on Fe-S cluster assembly.
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187
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Rasala BA, Muto M, Lee PA, Jager M, Cardoso RMF, Behnke CA, Kirk P, Hokanson CA, Crea R, Mendez M, Mayfield SP. Production of therapeutic proteins in algae, analysis of expression of seven human proteins in the chloroplast of Chlamydomonas reinhardtii. PLANT BIOTECHNOLOGY JOURNAL 2010; 8:719-33. [PMID: 20230484 PMCID: PMC2918638 DOI: 10.1111/j.1467-7652.2010.00503.x] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Recombinant proteins are widely used today in many industries, including the biopharmaceutical industry, and can be expressed in bacteria, yeasts, mammalian and insect cell cultures, or in transgenic plants and animals. In addition, transgenic algae have also been shown to support recombinant protein expression, both from the nuclear and chloroplast genomes. However, to date, there are only a few reports on recombinant proteins expressed in the algal chloroplast. It is unclear whether this is because of few attempts or of limitations of the system that preclude expression of many proteins. Thus, we sought to assess the versatility of transgenic algae as a recombinant protein production platform. To do this, we tested whether the algal chloroplast could support the expression of a diverse set of current or potential human therapeutic proteins. Of the seven proteins chosen, >50% expressed at levels sufficient for commercial production. Three expressed at 2%-3% of total soluble protein, while a forth protein accumulated to similar levels when translationally fused to a well-expressed serum amyloid protein. All of the algal chloroplast-expressed proteins are soluble and showed biological activity comparable to that of the same proteins expressed using traditional production platforms. Thus, the success rate, expression levels, and bioactivity achieved demonstrate the utility of Chlamydomonas reinhardtii as a robust platform for human therapeutic protein production.
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Affiliation(s)
- Beth A Rasala
- Department of Cell Biology and the Skaggs Institute for Chemical Biology, 10550 N. Torrey Pines Rd, La Jolla, CA92037, USA
| | - Machiko Muto
- Department of Cell Biology and the Skaggs Institute for Chemical Biology, 10550 N. Torrey Pines Rd, La Jolla, CA92037, USA
| | - Philip A Lee
- Department of Cell Biology and the Skaggs Institute for Chemical Biology, 10550 N. Torrey Pines Rd, La Jolla, CA92037, USA
| | - Michal Jager
- Department of Cell Biology and the Skaggs Institute for Chemical Biology, 10550 N. Torrey Pines Rd, La Jolla, CA92037, USA
| | | | - Craig A Behnke
- Sapphire Energy, 3115 Merryfield Rd., San Diego, CA 92121
| | - Peter Kirk
- Protelica, 26118 Research Pl, Hayward, CA 94545
| | | | | | - Michael Mendez
- Sapphire Energy, 3115 Merryfield Rd., San Diego, CA 92121
| | - Stephen P Mayfield
- Department of Cell Biology and the Skaggs Institute for Chemical Biology, 10550 N. Torrey Pines Rd, La Jolla, CA92037, USA
- Corresponding author: SPM:
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188
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Becker V, Schilling M, Bachmann J, Baumann U, Raue A, Maiwald T, Timmer J, Klingmüller U. Covering a Broad Dynamic Range: Information Processing at the Erythropoietin Receptor. Science 2010; 328:1404-8. [PMID: 20488988 DOI: 10.1126/science.1184913] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Verena Becker
- Division Systems Biology of Signal Transduction, DKFZ-ZMBH Alliance, German Cancer Research Center, 69120 Heidelberg, Germany
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189
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Abstract
The kidney is a highly sensitive oxygen sensor and plays a central role in mediating the hypoxic induction of red blood cell production. Efforts to understand the molecular basis of oxygen-regulated erythropoiesis have led to the identification of erythropoietin (EPO), which is essential for normal erythropoiesis and to the purification of hypoxia-inducible factor (HIF), the transcription factor that regulates EPO synthesis and mediates cellular adaptation to hypoxia. Recent insights into the molecular mechanisms that control and integrate cellular and systemic erythropoiesis-promoting hypoxia responses and their potential as a therapeutic target for the treatment of renal anemia are discussed in this review.
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Affiliation(s)
- Volker H Haase
- Department of Medicine, Vanderbilt School of Medicine, Nashville, Tennessee 37232, USA.
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190
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Revers L, Furczon E. An Introduction to Biologics and Biosimilars. Part I: Biologics: What are They and Where Do They Come from? Can Pharm J (Ott) 2010. [DOI: 10.3821/1913-701x-143.3.134] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Leigh Revers
- From the Master of Biotechnology Program, University of Toronto, Toronto, Ontario. Contact
| | - Eva Furczon
- From the Master of Biotechnology Program, University of Toronto, Toronto, Ontario. Contact
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191
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Integrity of the prolyl hydroxylase domain protein 2:erythropoietin pathway in aging mice. Blood Cells Mol Dis 2010; 45:9-19. [PMID: 20400342 DOI: 10.1016/j.bcmd.2010.03.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 03/01/2010] [Accepted: 03/09/2010] [Indexed: 01/28/2023]
Abstract
The central transcriptional response to hypoxia is mediated by the prolyl hydroxylase domain protein (PHD):hypoxia inducible factor (HIF) pathway. In this pathway, PHD prolyl hydroxylates and thereby negatively regulates the alpha-subunit of the transcription factor HIF (HIF-alpha). An important HIF target gene is that for erythropoietin (EPO), which controls red cell mass. Recent studies have identified PHD2 as the critical PHD isoform regulating the EPO gene. Other studies have shown that the inducibility of the HIF pathway diminishes as a function of age. Thus, an important question is whether the PHD2:EPO pathway is altered in the aging. Here, we employed a mouse line with a globally-inducible Phd2 conditional knockout allele to examine the integrity of the Phd2:Epo axis in young (six to eight months old) and aging (sixteen to twenty months old) mice. We find that acute global deletion of Phd2 results in a robust erythrocytosis in both young and aging mice, with both age groups showing marked extramedullary hematopoiesis in the spleen. Epo mRNA is dramatically upregulated in the kidney, but not in the liver, in both age groups. Conversely, other Hif targets, including Vegf, Pgk1, and Phd3 are upregulated in the liver but not in the kidney in both age groups. These findings have implications for targeting this pathway in the aging.
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192
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Epo is relevant neither for microvascular formation nor for the new formation and maintenance of mice skeletal muscle fibres in both normoxia and hypoxia. J Biomed Biotechnol 2010; 2010:137817. [PMID: 20414335 PMCID: PMC2855079 DOI: 10.1155/2010/137817] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 01/28/2010] [Accepted: 02/09/2010] [Indexed: 11/21/2022] Open
Abstract
Erythropoietin (Epo) and vascular growth factor (VEGF) are known to be involved in the regulation of cellular activity when oxygen transport is reduced as in anaemia or hypoxic conditions. Because it has been suggested that Epo could play a role in skeletal muscle development, regeneration, and angiogenesis, we aimed to assess Epo deficiency in both normoxia and hypoxia by using an Epo-deficient transgenic mouse model (Epo-TAgh). Histoimmunology, ELISA and real time RT-PCR did not show any muscle fiber atrophy or accumulation of active HIF-1α but an improvement of microvessel network and an upregulation of VEGFR2 mRNA in Epo-deficient gastrocnemius compared with Wild-Type one. In hypoxia, both models exhibit an upregulation of VEGF120 and VEGFR2 mRNA but no accumulation of Epo protein. EpoR mRNA is not up-regulated in both Epo-deficient and hypoxic gastrocnemius. These results suggest that muscle deconditioning observed in patients suffering from renal failure is not due to Epo deficiency.
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193
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Genc K, Egrilmez MY, Genc S. Erythropoietin induces nuclear translocation of Nrf2 and heme oxygenase-1 expression in SH-SY5Y cells. Cell Biochem Funct 2010; 28:197-201. [DOI: 10.1002/cbf.1639] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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194
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195
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Shi Z, Hodges VM, Dunlop EA, Percy MJ, Maxwell AP, El-Tanani M, Lappin TR. Erythropoietin-Induced Activation of the JAK2/STAT5, PI3K/Akt, and Ras/ERK Pathways Promotes Malignant Cell Behavior in a Modified Breast Cancer Cell Line. Mol Cancer Res 2010; 8:615-26. [PMID: 20353997 DOI: 10.1158/1541-7786.mcr-09-0264] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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196
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Breig O, Théoleyre O, Douablin A, Baklouti F. Subtle distinct regulations of late erythroid molecular events by PI3K/AKT-mediated activation of Spi-1/PU.1 oncogene autoregulation loop. Oncogene 2010; 29:2807-16. [PMID: 20190819 DOI: 10.1038/onc.2010.29] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Spi-1/PU.1 oncogene is downregulated as proerythroblasts undergo terminal differentiation. Insertion of the Friend virus upstream of the Spi-1/PU.1 locus leads to the constitutive upregulation of Spi-1/PU.1, and a subsequent block in the differentiation of the affected erythroblasts. We have shown that sustained overexpression of Spi-1/PU.1 also inhibits the erythroid splicing of protein 4.1R exon 16, irrespective of chemical induction of differentiation. Here, we show a positive feedback loop that couples constitutive phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling to high expression of Spi-1/PU.1 in Friend erythroleukemia cells. Inhibition of PI3K/AKT results in Spi-1/PU.1 downregulation in a stepwise manner and induces cell differentiation. Chromatin immunoprecipitation assays further supported the positive autoregulatory effect of Spi-1/PU.1. Mutational analysis indicated that Ser41, but not Ser148, is necessary for Spi-1/PU.1-mediated repression of hemoglobin expression, whereas both Ser residues are required for Spi-1/PU.1 inhibition of the erythroid splicing event. We further show that inhibition of the erythroid transcriptional and splicing events are strictly dependent on distinct Spi-1/PU.1 phosphorylation modifications rather than Spi-1/PU.1 expression level per se. Our data further support the fact that Spi-1/PU.1 inhibits 4.1R erythroid splicing through two different pathways, and bring new insights into the extracellular signal impact triggered by erythropoietin on late erythroid regulatory program, including pre-mRNA splicing.
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Affiliation(s)
- O Breig
- mRNA Metabolism in Normal and Pathological Cells, CGMC, CNRS, Université Lyon 1, Villeurbanne, France
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197
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Oxidative stress and protective effect of erythropoietin on methotrexate-induced esophageal damage. J Pediatr Hematol Oncol 2010; 32:108-12. [PMID: 20098338 DOI: 10.1097/mph.0b013e3181ccb678] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION An experimental study was conducted to investigate the role of oxidative stress and effects of erythropoietin (EPO) on methotrexate-induced esophageal damage. MATERIALS AND METHODS Twenty-four female Sprague-Dawley rats were equally divided into 3 groups: Sham operation animals (group S) were administered subcutaneous injections of 0.2 mL of 0.9% NaCl; control animals (group MTX) were administered subcutaneous injections of methotrexate (5 mg/kg) and EPO-treated animals (group EPO) were administered subcutaneous injections of methotrexate (5 mg/kg) and EPO (2000 IU/kg) once daily for 4 consecutive days. At the fifth day, the distal 1.5-cm esophageal segments were harvested for biochemical and histologic investigations. Oxidative damage was assessed by measuring the levels of malondialdehyde and nitric oxide, and activities of superoxide dismutase and catalase in homogenized samples of esophageal tissue. Histologic damage to esophageal tissue was scored and total tissue damage scores were calculated. RESULTS Malondialdehyde levels in the S and EPO groups were significantly lower than those in the MTX group (P<0.05). Catalase and superoxide dismutase activities, and nitric oxide levels in the S and EPO groups were significantly higher than those in the MTX group (P<0.05). Esophageal tissue damage was significantly less in the EPO group than that in the MTX group (P<0.05). CONCLUSIONS Free radicals elevate in methotrexate given rats' esophagus and EPO has significant preventive effects on methotrexate-induced oxidative damage of esophagus in a rat model.
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198
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The protective effect of erythropoietin on the acute phase of corrosive esophageal burns in a rat model. Pediatr Surg Int 2010; 26:195-201. [PMID: 19760200 DOI: 10.1007/s00383-009-2480-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/25/2009] [Indexed: 11/27/2022]
Abstract
INTRODUCTION An experimental study was conducted to investigate the effects of erythropoietin on the acute phase of esophageal burn damage induced by sodium hydroxide. MATERIALS AND METHODS A standard esophageal alkaline burn was produced by the application of 10% sodium hydroxide to the distal esophagus in an in vivo rat model. Fifty-six female rats were allocated into three groups: Group BC (baseline control, n = 8) rats were uninjured and untreated, Group PC (positive control, n = 24) rats were injured but untreated and Group EPO (erythropoietin-treated, n = 24) rats were injured and given subcutaneous erythropoietin (1,000 IU/kg per day), 15 min, 24, and 48 h after administration of the NaOH solution. Six animals from Group PC and six from Group EPO were killed at 4, 24, 48, and 72 h after application of NaOH to the esophagus. All of animals in Group BC were killed 4 h after exposure to 0.9% NaCl. Oxidative damage was assessed by measuring levels of malondialdehyde (MDA) and nitric oxide (NO), and activities of superoxide dismutase (SOD) and catalase (CAT) in homogenized samples of esophageal tissue. Histologic damage to esophageal tissue was scored by a single pathologist blind to groups. RESULTS MDA levels in the BC and EPO groups were significantly lower than those in the PC group (p < 0.05). CAT and SOD activities, and NO levels in the BC and EPO groups were significantly higher than in the PC group (p < 0.05). Esophageal tissue damage measured at 4, 24, 48, and 72 h after NaOH application was significantly less in the EPO group than in the PC group (p < 0.05). CONCLUSIONS When administered early after an esophageal burn induced by 10% sodium hydroxide in this rat model, erythropoietin significantly attenuated oxidative damage, as measured by biochemical markers and histologic scoring.
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199
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Skeletal muscle intrinsic functional properties are preserved in a model of erythropoietin deficient mice exposed to hypoxia. Pflugers Arch 2010; 459:713-23. [PMID: 20119684 DOI: 10.1007/s00424-009-0775-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 12/10/2009] [Accepted: 12/11/2009] [Indexed: 10/19/2022]
Abstract
Erythropoietin (Epo)-induced polycythemia is the main factor of adaptation to hypoxia. In this study, we analysed the effects of Epo deficiency on intrinsic functional properties of slow and fast twitch muscles in a model of erythropoietin deficient mice (Epo-TAg(h)) exposed to hypoxia. We hypothesised that Epo deficiency would be deleterious for skeletal muscle structure and phenotype, which could change its functional properties and alters the adaptive response to ambient hypoxia. Wild-type (WT) and Epo-TAg(h) mice were left in hypobaric chamber at 420 mm Hg pressure for 14 days. Soleus (SOL) and extensor digitorum longus (EDL) were analysed in vitro by mechanical measurements, immunohistological and biochemical analyses. The results were compared to those obtained in corresponding muscles of age-matched normoxic groups. Our data did not show any difference between the groups whatever the Epo deficiency and/or hypoxic conditions for twitch force, tetanic force, fatigue, typology and myosin heavy chain composition. Normoxic Epo-TAg(h) mice exhibit improved capillary-to-fibre ratio compared to WT mice in both SOL and EDL whereas no angiogenic effects of hypoxia or combined Epo-deficiency/hypoxia were observed. These results suggest that skeletal muscles possess a great capacity of adaptation to Epo deficiency. Then Epo deficiency is not a sufficient factor to modify intrinsic functional properties of skeletal muscles.
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200
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Nalbant D, Saleh M, Goldman FD, Widness JA, Veng-Pedersen P. Evidence of receptor-mediated elimination of erythropoietin by analysis of erythropoietin receptor mRNA expression in bone marrow and erythropoietin clearance during anemia. J Pharmacol Exp Ther 2010; 333:528-32. [PMID: 20103588 DOI: 10.1124/jpet.109.163568] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Erythropoietin (Epo) is the primary hormone that stimulates erythroid proliferation and differentiation through its cell surface receptor (EpoR) on erythroid progenitor cells. Previous studies have suggested that the bone marrow plays an important role in Epo's elimination. The changes in the EpoR mRNA levels and Epo's clearance in the bone marrow of 11 newborn lambs were studied to elucidate the role of EpoR in Epo's clearance under anemic conditions. Epo mRNA levels were measured by real-time polymerase chain reaction, and relative expression of EpoR was calculated by using the comparative CT method. The glyceraldehyde-3-phosphate dehydrogenase housekeeping gene was chosen as a control gene for the calculations. All lambs showed significant increase in bone marrow EpoR mRNA levels after phlebotomy-induced anemia. Epo's clearance determined from simultaneous pharmacokinetic studies with 125I-recombinant human Epo showed a significant increase after phlebotomy-induced anemia that was similar to the increase in EpoR. By day 28 after phlebotomy, EpoR mRNA levels and Epo clearance had returned toward baseline. These results indicate that the changes in Epo's clearance are not caused by body growth but result from significant changes in the pool of EpoR. A linear mixed-effect model was used to evaluate the quantitative relationship between EpoR and Epo's clearance. This analysis demonstrated a highly significant positive linear correlation between EpoR and Epo clearance. Together, these findings provide strong evidence that receptor-mediated Epo clearance is an important route for Epo's elimination.
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Affiliation(s)
- Demet Nalbant
- Division of Pharmaceutics, College of Pharmacy, University of Iowa, Iowa City, Iowa 52242, USA
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