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      Deferasirox Reduces Oxidative Stress in Patients With Transfusion Dependency

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          Abstract

          Background

          Iron chelation therapy is useful against the over-accumulation of iron and is expected to reduce oxidative stress resulting from the Fenton reaction and Haber-Weiss reaction. We monitored oxidative status and serum ferritin levels after in vivo administration of deferasirox (DFS) and studied the in vitro effects of iron chelators on neutrophil function.

          Methods

          Nine patients suffering from transfusion dependency were recruited for this study, and derivatives of reactive oxygen metabolite (dROM) tests to detect serum hydroperoxide levels were evaluated in addition to serum ferritin levels. Human neutrophil reactive oxygen species (ROS) production was determined with flow cytometry.

          Results

          Ferritin levels decreased after DFS treatment (P = 0.068), and a significant reduction in dROM levels was measured (P = 0.031). Fifty microM DFS significantly inhibited ROS production induced by fMLP in vitro (P < 0.0001), and tended to inhibit that induced by PMA. On the other hand, deferioxamine failed to inhibit ROS production even at high concentrations.

          Conclusions

          In vivo administration of DFS resulted in the reduction of oxidative stress, and this effect was considered to depend not only on a reduction in iron storage but also on the ability of DFS to inhibit neutrophil ROS production in vitro at clinically relevant plasma levels. Further studies are needed to examine the effects of iron chelators.

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          Most cited references17

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          Time-dependent prognostic scoring system for predicting survival and leukemic evolution in myelodysplastic syndromes.

          The aims of this study were to identify the most significant prognostic factors in myelodysplastic syndromes (MDS) taking into account both their values at clinical onset and their changes in time and to develop a dynamic model for predicting survival and leukemic evolution that can be applied at any time during the course of the disease. We studied a learning cohort of 426 MDS patients diagnosed at the Department of Hematology, San Matteo Hospital, Pavia, Italy, between 1992 and 2004, and a validation cohort of 739 patients diagnosed at the Heinrich-Heine-University Hospital, Düsseldorf, Germany, between 1982 and 2003. All patients were reclassified according to WHO criteria. Univariable and multivariable analyses were performed using Cox models with time-dependent covariates. The most important variables for the prognostic model were WHO subgroups, karyotype, and transfusion requirement. We defined a WHO classification-based prognostic scoring system (WPSS) that was able to classify patients into five risk groups showing different survivals (median survival from 12 to 103 months) and probabilities of leukemic evolution (P < .001). WPSS was shown to predict survival and leukemia progression at any time during follow-up (P < .001), and its prognostic value was confirmed in the validation cohort. WPSS is a dynamic prognostic scoring system that provides an accurate prediction of survival and risk of leukemic evolution in MDS patients at any time during the course of their disease. This time-dependent system seems particularly useful in lower risk patients and may be used for implementing risk-adapted treatment strategies.
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            Deferasirox is a powerful NF-kappaB inhibitor in myelodysplastic cells and in leukemia cell lines acting independently from cell iron deprivation by chelation and reactive oxygen species scavenging.

            Usefulness of iron chelation therapy in myelodysplastic patients is still under debate but many authors suggest its possible role in improving survival of low-risk myelodysplastic patients. Several reports have described an unexpected effect of iron chelators, such as an improvement in hemoglobin levels, in patients affected by myelodysplastic syndromes. Furthermore, the novel chelator deferasirox induces a similar improvement more rapidly. Nuclear factor-kappaB is a key regulator of many cellular processes and its impaired activity has been described in different myeloid malignancies including myelodysplastic syndromes. We evaluated deferasirox activity on nuclear factor-kappaB in myelodysplastic syndromes as a possible mechanism involved in hemoglobin improvement during in vivo treatment. Forty peripheral blood samples collected from myelodysplastic syndrome patients were incubated with 50 muM deferasirox for 18h. Nuclear factor-kappaB activity dramatically decreased in samples showing high basal activity as well as in cell lines, whereas no similar behavior was observed with other iron chelators despite a similar reduction in reactive oxygen species levels. Additionally, ferric hydroxyquinoline incubation did not decrease deferasirox activity in K562 cells suggesting the mechanism of action of the drug is independent from cell iron deprivation by chelation. Finally, incubation with both etoposide and deferasirox induced an increase in K562 apoptotic rate. Nuclear factor-kappaB inhibition by deferasirox is not seen from other chelators and is iron and reactive oxygen species scavenging independent. This could explain the hemoglobin improvement after in vivo treatment, such that our hypothesis needs to be validated in further prospective studies.
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              Action of chelators in iron-loaded cardiac cells: Accessibility to intracellular labile iron and functional consequences.

              Labile iron in hemosiderotic plasma and tissue are sources of iron toxicity. We compared the iron chelators deferoxamine, deferiprone, and deferasirox as scavengers of labile iron in plasma and cardiomyocytes at therapeutic concentrations. This comprised chelation of labile plasma iron (LPI) in samples from thalassemia patients; extraction of total cellular iron; accessing labile iron accumulated in organelles and preventing formation of reactive-oxidant species; and restoring impaired cardiac contractility. Neonatal rat cardiomyocytes were used for monitoring chelator extraction of LCI (labile cell iron) as 59Fe; assessing in situ cell iron chelation by epifluorescence microscope imaging using novel fluorescent sensors for iron and reactive oxygen species (ROS) selectively targeted to organelles, and monitoring contractility by time-lapse microscopy. At plasma concentrations attained therapeutically, all 3 chelators eliminated LPI but the orally active chelators rapidly gained access to the LCI pools of cardiomyocytes, bound labile iron, attenuated ROS formation, extracted accumulated iron, and restored contractility impaired by iron overload. The effect of deferoxamine at therapeutically relevant concentrations was primarily by elimination of LPI. The rapid accessibility of the oral chelators deferasirox and deferiprone to intracellular labile iron compartments renders them potentially efficacious for protection from and possibly reversal of cardiac damage induced by iron overload.
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                Author and article information

                Journal
                J Clin Med Res
                J Clin Med Res
                Elmer Press
                Journal of Clinical Medicine Research
                Elmer Press
                1918-3003
                1918-3011
                February 2013
                11 January 2013
                : 5
                : 1
                : 57-60
                Affiliations
                [a ]Faculty of Pharmacological Sciences, Himeji Dokkyo University, 7-Kami-ohno, Himeji, Hyogo, Japan
                [b ]Cell Analysis Center, Scientific Affairs, Sysmex Corporation, 1-Murotani, Nisiku, Kobe, Japan
                [c ]Department of Hematology and Oncology, Himeji Red Cross Hospital, 1-Shimoteno, Himeji, Hyogo, Japan
                [d ]Department of Hematology, Himeji Medical Center, 68-Honmachi, Himeji, Hyogo, Japan
                [e ]Department of Hematology, Akoh Central Hospital, 52-Somoncho, Akoh, Hyogo, Japan
                [f ]Faculty of Health Science, Kobe Tokiwa University, 2-Otanicho, Nagata-ku, Kobe, Hyogo, Japan
                [g ]Department of Pediatrics, Takasago Seibu Hospital, 1-Nakasuji, Takasago, Hyogo, Japan
                Author notes
                [h ]Corresponding author: Katsuyasu Saigo, Faculty of Pharmacological Science, Himeji Dokkyo University 7, Kami-ohno, Himeji, Hyogo 670-8524, Japan. Email: ksaigo@ 123456himeji-du.ac.jp
                Article
                10.4021/jocmr1180w
                3564569
                23390477
                0a7cb4ed-c822-4700-be3d-26aacf591f5a
                Copyright 2013, Saigo et al.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 30 October 2012
                Categories
                Short Communication

                Medicine
                deferasirox,oxidative stress,ferritin,drom,neutrophil
                Medicine
                deferasirox, oxidative stress, ferritin, drom, neutrophil

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