Deferiprone (L1) chelates pathologic iron deposits from membranes of intact thalassemic and sickle red blood cells both in vitro and in vivo

Abstract

Red blood cell (RBC) membranes from patients with the thalassemic and sickle hemoglobinopathies carry abnormal deposits of iron presumed to mediate a variety of oxidative-induced membrane dysfunctions. We hypothesized that the oral iron chelator deferiprone (L1), which has an enhanced capacity to permeate cell membranes, might be useful in chelating these pathologic iron deposits from intact RBCs. We tested this hypothesis in vitro by incubating L1 with RBCs from 15 patients with thalassemia intermedia and 6 patients with sickle cell anemia. We found that removal of RBC membrane free iron by L1 increased both as a function of time of incubation and L1 concentration. Thus, increasing the time of incubation of thalassemic RBCs with 0.5 mmol/L L1 from 0.5 to 6 hours, enhanced removal of their membrane free iron from 18% +/- 9% to 96% +/- 4%. Dose-response studies showed that incubating thalassemic RBC for 2 hours with L1 concentrations ranging from 0.125 to 0.5 mmol/L resulted in removal of membrane free iron from 28% +/- 15% to 68% +/- 11%. Parallel studies with sickle RBCs showed a similar pattern in time and dose responses. Deferoxamine (DFO), on the other hand, was ineffective in chelating membrane free iron from either thalassemic or sickle RBCs regardless of dose (maximum, 0.333 mmol/L) or time of incubation (maximum, 24 hours). In vivo efficacy of L1 was shown in six thalassemic patients whose RBC membrane free iron decreased by 50% +/- 29% following a 2-week course of L1 at a daily dose of 25 mg/kg. As the dose of L1 was increased to 50 mg/kg/d (n = 5), and then to 75 mg/kg/d (n = 4), 67% +/- 14% and 79% +/- 11%, respectively, of their RBC membrane free iron was removed. L1 therapy-- both in vitro and in vivo--also significantly attenuated the malondialdehyde response of thalassemic RBC membranes to in vitro stimulation with peroxide. Remarkably, the heme content of RBC membranes from L1-treated thalassemic patients decreased by 28% +/- 10% during the 3-month study period. These results indicate that L1 can remove pathologic deposits of chelatable iron from thalassemic and sickle RBC membranes, a therapeutic potential not shared by DFO. Furthermore, membrane defects possibly mediated by catalytic iron, such as lipid peroxidation and hemichrome formation, may also be alleviated, at least in part, by L1.

Hemolytic anemia induced by ribavirin therapy in patients with chronic hepatitis C virus infection: Role of membrane oxidative damage

“…Moreover, in vivo RBV treatment determined an increase in methemoglobin level, as well as in malondialdehyde (MDA) erythrocyte content, which is known to be a typical product of oxidative damage (Table 5). 37,38 In the present article we provide evidence for significant alterations of the erythrocyte membrane induced by RBV therapy, which are known to be associated with erythrophagocytic extravascular destruction. The signal for erythrocyte recognition and removal by phagocytes seemed to reside in the large amount of deposited autologous IgGs and C3 complement fragments, both secondary to band 3 aggrega-tion, observed in all patients ( Figs.…”

Redox and antioxidant systems of the malaria parasite Plasmodium falciparum

“…This is most apparent in erythrocytes infected with late parasite stages (Giribaldi et al ., 2001). These modifications are reminiscent of those found in erythrocytes of humans with red blood cell disorders such as sickle cell anaemia and a -and b -thalassaemias and also glucose 6-phosphate dehydrogenase deficiency and it is believed that the underlying mechanism for these transformations is the enhanced oxidative stress in the defective erythrocytes (Shalev et al ., 1995;Beppu et al ., 1996;Shalev and Hebbel, 1996;de Jong et al ., 1997;Aslan et al ., 2000). Interestingly, these red blood cell disorders and also glucose 6-phosphate dehydrogenase deficiency confer a certain degree of resistance to an infection with Plasmodium and often limit the severity of the disease (Roberts and Williams, 2003).…”

Role of Iron in Inducing Oxidative Stress in Thalassemia: Can It Be Prevented by Inhibition of Absorption and by Antioxidants?

“…Deferiprone alleviated membrane damage possibly mediated by catalytic iron, such as lipid peroxidation, measured by increased levels of malonyldialdehyde, a breakdown product of lipid membrane peroxidation, and hemichrome formation, and also reduced the KCl cotransporter activity. 29,30 In a few patients with Hb E/β thalassemia in Thailand, following administration of deferiprone alone for an average of 50 weeks, Hb levels increased concomitant with a decrease in transfusion requirements. 31 One possible explanation for this finding is that deferiprone acted like an antioxidant by removing excess free iron from the cells and, as a result, ROS generation was decreased.…”