Duality of Nrf2 in iron-overload cardiomyopathy

Cardiomyopathy deeply affects quality of life and mortality of patients with b-thalassemia or with transfusion-dependent myelodysplastic syndromes. Recently, a link between Nrf2 activity and iron metabolism has been reported in liver ironoverload murine models. Here, we studied C57B6 mice as healthy control and nuclear erythroid factor-2 knockout (Nrf2-/-) male mice aged 4 and 12 months. Eleven-month-old wild-type and Nrf2-/- mice were fed with either standard diet or a diet containing 2.5% carbonyl-iron (iron overload [IO]) for 4 weeks. We show that Nrf2-/- mice develop an age-dependent cardiomyopathy, characterized by severe oxidation, degradation of SERCA2A and iron accumulation. This was associated with local hepcidin expression and increased serum non-transferrin-bound iron, which promotes maladaptive cardiac remodeling and interstitial fibrosis related to overactivation of the TGF-b pathway. When mice were exposed to IO diet, the absence of Nrf2 was paradoxically protective against further heart iron accumulation. Indeed, the combination of prolonged oxidation and the burst induced by IO diet resulted in activation of the unfolded protein response (UPR) system, which in turn promotes hepcidin expression independently from heart iron accumulation. In the heart of Hbbth3/+ mice, a model of b-thalassemia intermedia, despite the activation of Nrf2 pathway, we found severe protein oxidation, activation of UPR system and cardiac fibrosis independently from heart iron content. We describe the dual role of Nrf2 when aging is combined with IO and its novel interrelation with UPR system to ensure cell survival. We open a new perspective for early and intense treatment of cardiomyopathy in patients with b-thalassemia before the appearance of heart iron accumulation.

IOX1 Fails to Reduce α-Globin and Mediates γ-Globin Silencing in Adult β0-Thalassemia/Hemoglobin E Erythroid Progenitor Cells

The accumulation of unbound α-globin chains in red blood cells is a crucial pathophysiology of β-thalassemia. IOX1 (5-carboxy-8-hydroxyquinoline) is a broad-spectrum 2-oxoglutarate (2OG)-dependent oxygenase inhibitor that can reduce α-globin mRNA expression in human cord blood erythroid progenitor cells. Therefore, IOX1 has been proposed as a potential compound for β-thalassemia treatment through the decrease inα-globin chain synthesis. However, there is no empirical evidence regarding the consequences of IOX1 in β-thalassemia. In this study, the therapeutic effects of IOX1 were investigated in β⁰-thalassemia/hemoglobin E (HbE) erythroid progenitor cells during in vitro erythropoiesis. The results indicated that IOX1 had no impact on α-globin gene expression, but it led instead to significant decreases in γ-globin and fetal hemoglobin (HbF, α₂γ₂) production without affecting well-known globin regulators: KLF1, BCL11A, LRF, and GATA1. In addition, differential mRNA expression of several genes in the hypoxia response pathway revealed the induction of EGLN1, the PHD2-encoding gene, as a result of IOX1 treatment. These findings suggested that IOX1 fails to lower α-globin gene expression; on the contrary, it mediates γ-globin and HbF silencing in β⁰-thalassemia/HbE erythroid progenitor cells. Because of the negative correlation of EGLN1 and γ-globin gene expression after IOX1 treatment, repurposing IOX1 to study the hypoxia response pathway and γ-globin regulation may provide beneficial information for β-thalassemia.

Increased zinc and albumin but lowered copper in children with transfusion-dependent thalassemia

BACKGROUND

Measurements of copper and zinc in transfusion-dependent thalassemia (TDT) show contradictory results.

AIM OF THE STUDY

To examine serum levels of these minerals in TDT in relation to iron overload indices and erythron variables.

METHODS

This study recruited 60 children with TDT and 30 healthy controls aged 3-12 years old.

RESULTS

Zinc was significantly higher in TDT children than in controls, while copper and the copper to zinc ratio were significantly lowered in TDT. Serum zinc was significantly associated with the number of blood transfusions and iron overload variables (including serum iron and TS%) and negatively with erythron variables (including hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin). Serum copper was significantly and negatively associated with the same iron overload and erythron variables. The copper to zinc ratio was significantly correlated with iron, TS%, ferritin, hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin. Albumin levels were significantly higher in TDT children than in control children.

CONCLUSION

Our results suggest that the increase in zinc in children with TDT may be explained by iron loading anemia and hemolysis and the consequent shedding of high amounts of intracellular zinc into the plasma. Increased albumin levels and treatment with Desferral may further contribute towards higher zinc levels in TDT. We suggest that the elevations in zinc in TDT are a compensatory mechanism protecting against infection, inflammation, and oxidative stress. Previous proposals for prophylactic use of zinc supplements in TDT may not be warranted.

Antibodies against the erythroferrone N-terminal domain prevent hepcidin suppression and ameliorate murine thalassemia

Erythroferrone (ERFE) is produced by erythroblasts in response to erythropoietin (EPO) and acts in the liver to prevent hepcidin stimulation by BMP6. Hepcidin suppression allows for the mobilization of iron to the bone marrow for the production of red blood cells. Aberrantly high circulating ERFE in conditions of stress erythropoiesis, such as in patients with β-thalassemia, promotes the tissue iron accumulation that substantially contributes to morbidity in these patients. Here we developed antibodies against ERFE to prevent hepcidin suppression and to correct the iron loading phenotype in a mouse model of β-thalassemia [Hbb(th3/+) mice] and used these antibodies as tools to further characterize ERFE's mechanism of action. We show that ERFE binds to BMP6 with nanomolar affinity and binds BMP2 and BMP4 with somewhat weaker affinities. We found that BMP6 binds the N-terminal domain of ERFE, and a polypeptide derived from the N terminus of ERFE was sufficient to cause hepcidin suppression in Huh7 hepatoma cells and in wild-type mice. Anti-ERFE antibodies targeting the N-terminal domain prevented hepcidin suppression in ERFE-treated Huh7 cells and in EPO-treated mice. Finally, we observed a decrease in splenomegaly and serum and liver iron in anti-ERFE-treated Hbb(th3/+) mice, accompanied by an increase in red blood cells and hemoglobin and a decrease in reticulocyte counts. In summary, we show that ERFE binds BMP6 directly and with high affinity, and that antibodies targeting the N-terminal domain of ERFE that prevent ERFE-BMP6 interactions constitute a potential therapeutic tool for iron loading anemias.

Interaction of Transfusion and Iron Chelation in Thalassemias

The relationship between blood transfusion intensity, chelatable iron pools, and extrahepatic iron distribution is described in thalassemia. Risk factors for cardiosiderosis are discussed with particular reference to the balance of transfusional iron loading rate and transferrin-iron utilization rate as marked by plasma levels of soluble transferrin receptors. Low transfusion regimens increase residual erythropoiesis allowing for apotransferrin-dependent clearance of non-transferrin-bound iron species otherwise destined for myocardium. The impact of transfusion rates on chelation dosing required for iron balance is also shown.

Beyond transfusion therapy: new therapies in thalassemia including drugs, alternate donor transplant, and gene therapy

Transfusion combined with chelation therapy for severe β thalassemia syndromes (transfusion-dependent thalassemia [TDT]) has been successful in extending life expectancy, decreasing comorbidities and improving quality of life. However, this puts lifelong demands not only on the patients but also on the health care systems that are tasked with delivering long-term treatment and comprehensive support. Prevention programs and curative approaches are therefore an important part of overall strategy. Curative treatments alter the dynamic of a patient's health care costs, from financial commitment over 50 years, into a potential "one-off" investment. Since the 1980s, this has usually been available only to the 30% or so of young children with matched sibling donors. By improving the safety of matched related donors and haploidentical hematopoietic stem cell transplants, the potential size of the donor pool for curative therapies may be increased. Recent advances in gene therapy demonstrate that even patients lacking a matched donor can be rendered transfusion independent with an autograft of genetically modified autologous stem cells, with a low short-term risk. Noncurative treatments are also of potential value by decreasing use of blood and chelators and decreasing hospital visits. An example is luspatercept, an activin-receptor trap that modifies transforming growth factor-β signaling, thereby increasing the efficiency of erythropoiesis. This has entered phase 3 clinical trials for TDT and non-TDT and, usefully increases in both Hb and quality of life in non-TDT as well as decreasing transfusion requirements in TDT. Other novel noncurative treatments are entering clinical trials such improvement of erythropoiesis through pharmacological manipulation of hepcidin and iron metabolism.

Intestinal calcium transport and its regulation in thalassemia: interaction between calcium and iron metabolism

Osteoporosis and derangement of calcium homeostasis are common complications of thalassemia. Despite being an important process for bone and calcium metabolism, little is known about intestinal calcium transport in thalassemia. Recent reports of decreases in both intestinal calcium transport and bone mineral density in thalassemic patients and animal models suggested that defective calcium absorption might be a cause of thalassemic bone disorder. Herein, the possible mechanisms associated with intestinal calcium malabsorption in thalassemia are discussed. This includes alterations in the calcium transporters and hormonal controls of the transcellular and paracellular intestinal transport systems in thalassemia. In addition, the effects of iron overload on intestinal calcium absorption, and the reciprocal interaction between iron and calcium transport in thalassemia are elaborated. Understanding the mechanisms underlining calcium malabsorption in thalassemia would lead to development of therapeutic agents and mineral supplements that restore calcium absorption as well as prevent osteoporosis in thalassemic patients.

What can we learn from ineffective erythropoiesis in thalassemia?

Erythropoiesis is a dynamic process regulated at multiple levels to balance proliferation, differentiation and survival of erythroid progenitors. Ineffective erythropoiesis is a key feature of various diseases, including β-thalassemia. The pathogenic mechanisms leading to ineffective erythropoiesis are complex and still not fully understood. Altered survival and decreased differentiation of erythroid progenitors are both critical processes contributing to reduced production of mature red blood cells. Recent studies have identified novel important players and provided major advances in the development of targeted therapeutic approaches. In this review, β-thalassemia is used as a paradigmatic example to describe our current knowledge on the mechanisms leading to ineffective erythropoiesis and novel treatments that may have the potential to improve the clinical phenotype of associated diseases in the future.

Impact of bone disease and pain in thalassemia

Conventional treatment of thalassemia, namely regular blood transfusion and iron chelation, improves perspectives and quality of life; however, successful treatment leads to more time in which long-term complications such as bone disease can develop. Thalassemia bone disease (TBD) is unique: all aspects, from bone anatomy and bone quality to mineral density, may be affected, with important morbidity including osteoporosis, fractures, spinal deformities, nerve compression, and pain. Clinical presentations include growth impairment, rickets-like features, back pain, spinal deformities, any sign of nerve compression, severe osteoporosis, and fragility fractures. Age, history, physical examination, and diagnostic tests support orientation on risk factors. These include bone marrow expansion, toxicity from iron overload and iron chelation, endocrine dysfunctions (hypogonadism, hypohyperparathyroidism, hypothyroidism, growth hormone deficiency, diabetes), and vitamin (D, C, K) and zinc deficiencies. Several of these may coexist in an individual for a long time and at different degrees, making clarification of the relative contribution and selection of the best therapeutic options a challenge. Milestones for prevention of TBD are early and full inhibition of bone marrow hyperplasia and iron toxicity. Empowering patients' positive resources is key for achieving long-term healthy habits with regard to diet, physical activity, sunlight exposure, and lifestyle. Pain, related or unrelated to bone disease, is frequent in thalassemia. The most important targets for the hematologist include having an expert orientation on disease-related causes of pain, driving differential diagnosis, providing effective pain relief and, where feasible, removing the cause.

Oxidative status of platelets in normal and thalassemic blood

Chronic platelet activation may be involved in thromboembolic complications, a leading cause of morbidity and mortality in β-thalassemia. Oxidative stress, with the generation of reactive oxygen species (ROS), is suspected to play a role in the pathophysiology of thalassemia and cardiovascular disorders. In the present study, we adapted flow cytometric techniques to measure oxidative state markers, ROS generation and reduced glutathione (GSH) content in platelets. Our results show that platelets obtained from β-thalassemic patients contain higher ROS and lower GSH levels than do platelets from normal donors, indicating a state of oxidative stress. In the absence of any known inherent abnormality in thalassemia platelets, this may be attributed to continuous exposure to oxidative insults from extra-platelet sources. We found that exposure of platelets to oxidants such as hydrogen peroxide and tertbutylhydroperoxide or to the platelet activators thrombin, calcium ionophore or phorbol myristate acetate stimulated the platelets’ oxidative stress.This was also increased by plasma of thalassemia patients, and decreased following treatment of the plasma with the iron-chelator Desferoxamin. Iron and hemin, the levels of which are augmented in plasma of thalassemia patients, stimulated the platelets’ oxidative stress.The oxidative status of the platelets was also affected by red blood cells (RBC); it was higher in normal platelets incubated with thalassemic RBC than with normal RBC. Normal RBC stimulated with hydrogen peroxide had a greater effect on platelets than did unstimulated RBC.The platelets’ oxidative stress was ameliorated by antioxidants such as N-acetyl-L-cysteine and vitamin C. Our findings indicate that in thalassemia, platelets undergo a state of oxidative stress, leading to their activation and potentially to thromboembolic consequences, and suggest that this hypercoagulable state might be treated with antioxidants.

First study on iron complexes in blood and organ samples from thalassaemic and normal laboratory mice using Mössbauer spectroscopy

Measurements of iron complexes and iron stores in the body are crucial for evaluation and management of chelation therapy targeted against iron accumulation or overload in blood and organs. In this work, blood and tissue samples from one normal and one thalassaemic laboratory mouse were studied using ⁵⁷Fe Mössbauer spectroscopy at 78 K for the first time. In contrast to human patients, these laboratory mice did not receive any medical treatment, thus the iron components present in the samples are not altered from their natural state. The Mössbauer spectra of blood, liver and spleen samples of the thalassaemic mouse were found to differ in shape and iron content compared with corresponding spectra of the normal mouse. These results demonstrate a basis for further exploitation of the thalassaemic mouse model to study thalassaemia and its treatment in more detail using Mössbauer spectroscopy.

Effect of Iron Chelation Therapy on Glucose Metabolism in Non-Transfusion-Dependent Thalassaemia

AIMS

To compare insulin sensitivity, β-cell function and iron status biomarkers in non-transfusion-dependent thalassaemia (NTDT) with iron excess during pre- and post-iron chelation.

METHODS

Subjects with NTDT, aged older than 10 years, with serum ferritin >300 ng/ml, were included. Iron chelation with deferasirox (10 mg/kg/day) was prescribed daily for 6 months.

RESULTS

Ten patients with a median age of 17.4 years were enrolled. The comparison between pre- and post-chelation demonstrated significantly lower iron load: median serum ferritin (551.4 vs. 486.2 ng/ml, p = 0.047), median TIBC (211.5 vs. 233.5 µg/dl, p = 0.009) and median non-transferrin binding iron (5.5 vs. 1.4 µM, p = 0.005). All patients had a normal oral glucose tolerance test (OGTT) both pre- and post-chelation. However, fasting plasma glucose was significantly reduced after iron chelation (85.0 vs.79.5 mg/dl, p = 0.047). MRI revealed no significant changes of iron accumulation in the heart and liver after chelation, but there was a significantly lower iron load in the pancreas, assessed by higher T2* at post-chelation compared with pre-chelation (41.9 vs. 36.7 ms, p = 0.047). No adverse events were detected.

CONCLUSIONS

A trend towards improving insulin sensitivity and β-cell function as well as a reduced pancreatic iron load was observed following 6 months of iron chelation (TCTR20160523003).

Effects of iron overload condition on liver toxicity and hepcidin/ferroportin expression in thalassemic mice

AIMS

Although iron-overload conditions can be found in β-thalassemic patients, resulting in cellular damage, particularly in the liver, the mechanism for this iron-mediated hepatic injury specifically in β-thalassemic (HT) mice is unclear. This study aimed to investigate the roles of L-type calcium channels (LTCC), T-type calcium channels (TTCC) and divalent metal transporter1 (DMT1) in iron-mediated hepatic injury in HT mice.

MAIN METHODS

Iron chelator deferoxamine (DFO), LTCC blocker, TTCC blocker and DMT1 blocker were used to determine the roles of these channels regarding liver iron accumulation, apoptosis and iron regulatory protein expression in HT mice.

KEY FINDINGS

TTCC and DMT1 blockers and DFO decreased liver iron and malondialdehyde (MDA) in HT mice indicating their antioxidant effects, whereas LTCC blocker produced no decrease in liver iron or MDA. However, only DFO decreased liver apoptosis through the reduced Bax/Bcl-2 ratio in wild type (WT) mice. The levels of iron regulatory hormone hepcidin were markedly higher in HT mice even before iron loading while ferroportin levels did not alter. Each of the pharmacological interventions increased ferroportin protein back to normal levels only in WT while HT mice showed no difference.

SIGNIFICANCE

Thalassemic mice have different hepcidin/ferroportin and apoptotic protein expression as a defense mechanism to iron-overload compared with those in WT mice. DFO was the most effective intervention in preventing liver apoptosis under iron-overload conditions in WT but did not have the same effect in HT mice.

Status of oxidant, antioxidantand serum enzymes in thalassaemic children receiving multiple blood transfusions

OBJECTIVE

To determine the levels of oxidant, antioxidant and serum enzymes in thalassaemic children receiving multiple blood transfusions.

METHODS

The case-control study was done from February to August 2012, and comprised thalassaemic children receiving multiple blood transfusions at Allied Hospital, Ali Zeb Foundation, and the Thalassaemia Centre in Hilal-e-Ahmar Hospital, Faisalabad, Pakistan. Healthy subjects were also screened for any related disease condition that could prejudice the results. Blood samples were analysed for the values of total oxidant status, total antioxidant capacity, serum malondialdehyde, catalase, paraoxonase, arylesterase, glutathione peroxidase and ceruloplasmin.

RESULTS

There were 180 children in the study; 90(50%) cases and 90(50%) controls. Of the cases, 48(53.3%) were under-weight while the weight of 42(46.7%) was in the normal range. The values of total oxidant status and total antioxidant capacity were significantly (p<0.01) higher in thalassaemic children compared to normal values. Serum malondialdehyde and catalase levels were also considerably elevated (p<0.05), suggesting the increased activity of these enzymes. However, the concentrations of serum paraoxonase, arylesterase, glutathione peroxidase were significantly (p<0.01) lower in cases than the controls, displaying diminished activities during multiple blood transfusions in these patients.

CONCLUSIONS

Multiple blood transfusions disconcert the levels of oxidants, antioxidants and serum enzymes of thalassaemic children. Oxidative damage is seen because of the increased iron overload in these patients. Hence, regular evaluation of oxidant and antioxidant status should be monitored in thalassaemic patients during initial few years of life.

Pulmonary hypertension in non-transfusion-dependent thalassemia: Correlation with clinical parameters, liver iron concentration, and non-transferrin-bound iron

BACKGROUND

Pulmonary hypertension is a major cardiac complication in non-transfusion-dependent thalassemia (NTDT). Several clinical and laboratory parameters, including iron overload, have been shown to have a positive correlation with the incidence of pulmonary hypertension. Non-transferrin-bound iron (NTBI) is a form of free-plasma iron that is a good indicator of iron overload.

OBJECTIVES

The aim of this study was to determine the prevalence of pulmonary hypertension in patients with NTDT and to investigate its correlation with the clinical parameters, liver iron concentration (LIC) and NTBI.

METHODS

Patients with NTDT were evaluated using echocardiography, and magnetic resonance imaging for cardiac T2* and LIC. Pulmonary hypertension was defined as peak tricuspid regurgitation velocity ≥2.9 m/s measured using trans-thoracic echocardiography. Clinical parameters and the status of iron overload as determined by LIC, serum ferritin, and NTBI level were evaluated for their association with pulmonary hypertension.

RESULTS

Of 76 NTDT patients, mean age 23.7 ± 8.5 years, seven patients (9.2%) had pulmonary hypertension. Previous splenectomy (71.4 vs. 24.6%, P-value 0.019), higher cumulative red blood cell (RBC) transfusions (received ≥10 RBC transfusions 85.7 vs. 33.3%, P-value 0.011), higher nucleated RBCs (353 ± 287 vs. 63 ± 160/100 white blood cells, P-value <0.001), and a high NTBI level (5.7 ± 3.0 vs. 3.3 ± 2.8 µmol/l, P-value 0.034) were associated with pulmonary hypertension. There was no significant correlation between LIC or serum ferritin and pulmonary hypertension.

CONCLUSION

Pulmonary hypertension in NTDT is common, and is associated with splenectomy and its related factors. NTBI level shows a significant correlation with pulmonary hypertension.

Effect of L-type calcium channel blocker (amlodipine) on myocardial iron deposition in patients with thalassaemia with moderate-to-severe myocardial iron deposition: protocol for a randomised, controlled trial

INTRODUCTION

Sideroblastic cardiomyopathy secondary to repeated blood transfusions is a feared complication in thalassaemia. Control of myocardial iron is thus becoming the cornerstone of thalassaemia management. Recent evidence suggests a role for L-type Ca(2+) channels in mediating iron uptake by the heart. Blocking the cellular iron uptake through these channels may add to the benefit of therapy to standard chelation in reducing myocardial iron. We aim to determine the efficacy of amlodipine (a calcium channel blocker) as an adjunct to standard aggressive chelation in retarding myocardial iron deposition in thalassaemics with or without cardiomyopathy.

OUTCOMES

The primary outcome is to compare the efficacy of amlodipine+chelation (intervention) versus standard chelation (control) in retarding myocardial iron deposition. Secondary outcomes include the effect of amlodipine therapy on systolic and diastolic function, strain and strain rate and liver iron content.

METHODS AND ANALYSIS

This is a single-centre, parallel-group, prospective randomised control trial. Twenty patients will be randomised in a 1:1 allocation ratio into the intervention and control arms. In addition to conventional echocardiography, MRI T2* values for assessment of cardiac and liver iron load will be obtained at baseline and at 6 and 12 months. Cardiac T2* will be reported as the geometric mean and per cent coefficient of variation, and an increase in cardiac T2* values from baseline will be used as an end point to compare the efficacy of therapy. A p Value of <0.05 will be considered significant.

STUDY SETTING

Department of Pediatric and Child Health, Aga Khan University Hospital, Karachi, Pakistan.

ETHICS AND DISSEMINATION

This study has been approved by the Ethics Review Committee and Clinical Trials Unit at The Aga Khan University with respect to scientific content and compliance with applicable research and human subjects regulations. Findings will be reported through scientific publications and research conferences and project summary papers for participants.

TRIAL REGISTRATION NUMBER

ClinicalTrials.Gov. Registration no: NCT02065492.

Relationship among chelator adherence, change in chelators, and quality of life in thalassemia

PURPOSE

Thalassemia, a chronic blood disease, necessitates life-long adherence to blood transfusions and chelation therapy to reduce iron overload. We examine stability of health-related quality of life (HRQOL) in thalassemia and adherence to chelation therapy over time, especially after changes in chelator choice.

METHODS

Thalassemia Longitudinal Cohort participants in the USA, UK, and Canada completed the SF-36v2 (ages 14+) and the PF-28 CHQ (parents of children <14 years). Chelation adherence was defined as self-reported percent of doses administered in the last 4 weeks.

RESULTS

Two hundred and fifty-eight adults/adolescents (mean 29.7 years) and 133 children (mean 8.5 years) completed a mean of 2.8-years follow-up. Children made few chelator changes, whereas a mean of 2.2 changes was observed among the 37% of adults/adolescents who made chelator changes, mainly due to patient preference or medical necessity. Physical HRQOL improved among those with lower iron burden (better health status) at baseline who made a single change in chelator, but declined among participants with multiple changes and/or high iron burden (worse health status). Mental health improved among participants with lower iron burden, but iron overload was negatively associated with social functioning. Adherence did not significantly change over follow-up except for an increase after a change from deferoxamine (DFO) infusion to oral deferasirox (p = 0.03). Predictors of lower adherence for adults/adolescents at follow-up included side effects, smoking, younger age, problems preparing DFO, increased number of days per week DFO prescribed, and lower physical quality of life .

CONCLUSIONS

Strategies to balance medical needs with family, work, and personal life may assist in adherence.

Running exercise alleviates trabecular bone loss and osteopenia in hemizygous β-globin knockout thalassemic mice

A marked decrease in β-globin production led to β-thalassemia, a hereditary anemic disease associated with bone marrow expansion, bone erosion, and osteoporosis. Herein, we aimed to investigate changes in bone mineral density (BMD) and trabecular microstructure in hemizygous β-globin knockout thalassemic (BKO) mice and to determine whether endurance running (60 min/day, 5 days/wk for 12 wk in running wheels) could effectively alleviate bone loss in BKO mice. Both male and female BKO mice (1-2 mo old) showed growth retardation as indicated by smaller body weight and femoral length than their wild-type littermates. A decrease in BMD was more severe in female than in male BKO mice. Bone histomorphometry revealed that BKO mice had decreases in trabecular bone volume, trabecular number, and trabecular thickness, presumably due to suppression of osteoblast-mediated bone formation and activation of osteoclast-mediated bone resorption, the latter of which was consistent with elevated serum levels of osteoclastogenic cytokines IL-1α and -1β. As determined by peripheral quantitative computed tomography, running increased cortical density and thickness in the femoral and tibial diaphyses of BKO mice compared with those of sedentary BKO mice. Several histomorphometric parameters suggested an enhancement of bone formation (e.g., increased mineral apposition rate) and suppression of bone resorption (e.g., decreased osteoclast surface), which led to increases in trabecular bone volume and trabecular thickness in running BKO mice. In conclusion, BKO mice exhibited pervasive osteopenia and impaired bone microstructure, whereas running exercise appeared to be an effective intervention in alleviating bone microstructural defect in β-thalassemia.

Inborn defects in the antioxidant systems of human red blood cells

Red blood cells (RBCs) contain large amounts of iron and operate in highly oxygenated tissues. As a result, these cells encounter a continuous oxidative stress. Protective mechanisms against oxidation include prevention of formation of reactive oxygen species (ROS), scavenging of various forms of ROS, and repair of oxidized cellular contents. In general, a partial defect in any of these systems can harm RBCs and promote senescence, but is without chronic hemolytic complaints. In this review we summarize the often rare inborn defects that interfere with the various protective mechanisms present in RBCs. NADPH is the main source of reduction equivalents in RBCs, used by most of the protective systems. When NADPH becomes limiting, red cells are prone to being damaged. In many of the severe RBC enzyme deficiencies, a lack of protective enzyme activity is frustrating erythropoiesis or is not restricted to RBCs. Common hereditary RBC disorders, such as thalassemia, sickle-cell trait, and unstable hemoglobins, give rise to increased oxidative stress caused by free heme and iron generated from hemoglobin. The beneficial effect of thalassemia minor, sickle-cell trait, and glucose-6-phosphate dehydrogenase deficiency on survival of malaria infection may well be due to the shared feature of enhanced oxidative stress. This may inhibit parasite growth, enhance uptake of infected RBCs by spleen macrophages, and/or cause less cytoadherence of the infected cells to capillary endothelium.

Use of portable X-ray fluorescence (PXRF) in vivo as an alternative technique for the assessment of iron levels in patients with thalassemia and hemochromatosis

This work investigated the viability of the portable x-ray fluorescence (PXRF) technique as a means of measuring iron levels in patients suffering from thalassemia major (beta-thalassemia) and hereditary hemochromatosis (HH or Haemochromatosis) or other iron-overload conditions. Measurements were conducted at the University Hospital Blood Center and in the Laboratory of Applied Nuclear Physics at the State University of Londrina, Brazil. One thalassemia major patient and four healthy people were grouped. A PXRF system consisting of a Pu x-ray source and a SiPIN diode detector was used for measurements in vivo on the hand of each patient. The measuring system was calibrated with phantoms of aqueous solution doped with 15 to 150 ppm of iron. The duration of each measurement was 50 s. The detection limit (LLD) reached for iron was 13 ppm. The radiation dose on the skin was 10 mSv. The thalassemia patient presented 74 ± 6 ppm of iron, whereas the healthy people presented an average of 53 ± 5 ppm of iron. The results are in accord with the literature, which shows iron levels in the skin to be between 15 - 60 ppm for healthy people and between 70 - 150 ppm for thalassemia major patients. This work concluded that it is viable to apply the XRF methodology to follow thalassemia major and HH patients.

Protein antioxidants in thalassemia

It is common knowledge that thalassemic patients are under significant oxidative stress. Chronic hemolysis, frequent blood transfusion, and increased intestinal absorption of iron are the main factors that result in iron overload with its subsequent pathophysiologic complications. Iron overload frequently associates with the generation of redox-reactive labile iron, which in turn promotes the production of other reactive oxygen species (ROS). If not neutralized, uncontrolled production of ROS often leads to damage of various intra- and extracellular components such as DNA, proteins, lipids, and small antioxidant molecules among others. A number of endogenous and exogenous defense mechanisms can neutralize and counteract the damaging effects of labile iron and the reactive substances associated with it. Endogenous antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and ferroxidase, may directly or sequentially terminate the activities of ROS. Nonenzymatic endogenous defense mechanisms include metal binding proteins (ceruloplasmin, haptoglobin, albumin, and others) and endogenously produced free radical scavengers (glutathione (GSH), ubiquinols, and uric acid). Exogenous agents that are known to function as antioxidants (vitamins C and E, selenium, and zinc) are mostly diet-derived. In this review, we explore recent findings related to various antioxidative mechanisms operative in thalassemic patients with special emphasis on protein antioxidants.

Iron and hepcidin: a story of recycling and balance

To avoid iron deficiency and overload, iron availability is tightly regulated at both the cellular and systemic levels. The liver peptide hepcidin controls iron flux to plasma from enterocytes and macrophages through degradation of the cellular iron exporter ferroportin. The hepcidin-ferroportin axis is essential to maintaining iron homeostasis. Genetic inactivation of proteins of the hepcidin-activating pathway causes iron overload of varying severity in human and mice. Hepcidin insufficiency and increased iron absorption are also characteristic of anemia due to ineffective erythropoiesis in which, despite high total body iron, hepcidin is suppressed by the high erythropoietic activity, worsening both iron overload and anemia in a vicious cycle. Hepcidin excess resulting from genetic inactivation of a hepcidin inhibitor, the transmembrane protease serine 6 (TMPRSS6) leads to a form of iron deficiency refractory to oral iron. Increased hepcidin explains the iron sequestration and iron-restricted erythropoiesis of anemia associated with chronic inflammatory diseases. In mice, deletion of TMPRSS6 in vivo has profound effects on the iron phenotype of hemochromatosis and beta-thalassemia. Hepcidin manipulation to restrict iron is a successful strategy to improve erythropoiesis in thalassemia, as shown clearly in preclinical studies targeting TMPRSS6; attempts to control anemia of chronic diseases by antagonizing the hepcidin effect are ongoing. Finally, the metabolic pathways identified from iron disorders are now being explored in other human pathologic conditions, including cancer.

Oxidative damage and genotoxicity biomarkers in transfused and untransfused thalassemic subjects

Chronic anemia and tissue hypoxia increase intestinal iron absorption and mitochondrial impairment in thalassemic patients. Regular blood transfusions improve hemoglobin levels but determine an iron overload that induces reactive oxygen species (ROS) overproduction. The aim of this study was to assess cellular oxidative damage by detection of ROS, lipid peroxidation, 8-oxo-dG, and mitochondrial transmembrane potential (Δψ(m)) in transfused and untransfused thalassemic patients. We have also evaluated genotoxicity by CBMN and comet assay. Our data show that ROS and lipid hydroperoxides are significantly higher in thalassemic patients than in controls, especially in untransfused thalassemia intermedia patients. Moreover, the latter have a significant decrease in Δψ(m) that highlights the energetic failure in hypoxic state and the ROS overproduction in the respiratory chain. 8-OHdG levels are higher in thalassemics than in controls, but do not differ significantly between the two patient groups. Both genotoxicity biomarkers highlight the mutagenic potential of hydroxyl radicals released by iron in the Fenton reaction. Values for percentage of DNA in the comet tail and micronuclei frequency, significantly higher in transfused patients, could also be due to active hepatitis C virus infection and to the many drug treatments. Our biomonitoring study confirms the oxidative damage in patients with thalassemia major and shows an unexpected cellular oxidative damage in untransfused thalassemic patients. In addition to iron overload, the results highlight the important role played by hypoxia-driven mitochondrial ROS overproduction in determining oxidative damage in β-thalassemias.

Iron mobilization using chelation and phlebotomy

Knowledge of the basic mechanisms involved in iron metabolism has increased greatly in recent years, improving our ability to deal with the huge global public health problems of iron deficiency and overload. Several million people worldwide suffer iron overload with serious clinical implications. Iron overload has many different causes, both genetic and environmental. The two most common iron overload disorders are hereditary haemochromatosis and transfusional siderosis, which occurs in thalassaemias and other refractory anaemias. The two most important treatment options for iron overload are phlebotomy and chelation. Phlebotomy is the initial treatment of choice in haemochromatosis, while chelation is a mainstay in the treatment of transfusional siderosis. The classical iron chelator is deferoxamine (Desferal), but due to poor gastrointestinal absorption it has to be administered intravenously or subcutaneously, mostly on a daily basis. Thus, there is an obvious need to find and develop new effective iron chelators for oral use. In later years, particularly two such oral iron chelators have shown promise and have been approved for clinical use, namely deferiprone (Ferriprox) and deferasirox (Exjade). Combined subcutaneous (deferoxamine) and oral (deferiprone) treatment seems to hold particular promise.

Non-transferrin bound iron in Thalassemia: differential detection of redox active forms in children and older patients

Non-transferrin bound iron (NTBI) is commonly detected in patients with systemic iron overload whose serum iron-binding capacity has been surpassed. It has been perceived as an indicator of iron overload, impending organ damage and a chelation target in poly-transfused thalassemia patients. However, NTBI is a heterogeneous entity comprising various iron complexes, including a significant redox-active and readily chelatable fraction, which we have designated as "labile plasma iron" (LPI). We found that LPI levels can be affected by plasma components such as citrate, uric acid, and albumin. However, the inclusion of a mild metal mobilizing agent in the LPI assay (designated here as "eLPI"), at concentrations that do not affect transferrin-bound iron, largely overcomes such effects and provides a measure of the full NTBI content. We analyzed three distinct groups of poly-transfused, iron overloaded thalassemia patients: non-chelated children (3-13 yrs, Gaza, Palestine), chelated adolescents-young adults (13-28 yrs, Israel), and chelated adults (27-61 yrs, Israel) for LPI and eLPI. The eLPI levels in all three groups were roughly commensurate (r(2) = 0.61-0.75) with deferrioxamine-detectable NTBI, i.e., DCI. In older chelated patients, eLPI levels approximated those of LPI, but in poly-transfused unchelated children eLPI was notably higher than LPI, a difference attributed to plasma properties affected by labile iron due to lack of chelation, possibly reflecting age-dependent attrition of plasma components. We propose that the two formats of NTBI measurement presented here are complementary and used together could provide more comprehensive information on the forms of NTBI in patients and their response to chelation.

Dual-energy X-ray absorptiometry with serum ferritin predicts liver iron concentration and changes in concentration better than ferritin alone

Accurate assessment of liver iron concentration (LIC) is critical for optimal monitoring of iron toxicity in multitransfused patients. Serum ferritin is the most widely used although its association to LIC is only modest. We studied if a liver-specific measure using dual-energy X-ray absorptiometry (DXA) systems could improve LIC estimates over ferritin alone in Thalassemia (Thal) patients. Thirty-seven patients with Thal (19.2 ± 9.0 yr, 20 male) were studied and 10 had multiple visits. Height, weight, ferritin, whole-body DXA, and hepatic superconducting quantum interference device (SQUID) were measured within 5 wk. DXA hepatic density was measured using right rib, whole liver, and multiple subliver regions. The best agreement to SQUID LIC was found using a combination of ferritin, weight, DXA subliver region 3 bone mineral content (BMC), and right rib BMC. DXA with ferritin improved the ferritin alone correlation from R(2)=0.35 to R(2)=0.62. Serial LIC changes using DXA were associated with serial SQUID changes (r=0.73, p=0.02). Changes in ferritin alone were not significant (p=0.06). We conclude that the addition of whole-body DXA measures and body weight substantially increased the accuracy of LIC and change in LIC estimates over the use of ferritin alone and could be useful when magnetic resonance imaging or SQUID is not available.

[Status of iron metabolism and erythropoietic proliferation in children with various genotypes of thalassemia]

OBJECTIVE

To study the status of iron metabolism and erythropoietic proliferation in children with various genotypes of thalassemia.

METHODS

Serum concentrations of ferritin (SF), transferrin receptor (sTfR) and erythropoietin (EPO) were measured in 158 children with thalassemia. The differences in the concentrations of the three indices among children with different genotypes of thalassemia were compared. The correlations of the hemoglobin level with sereum SF, sTfR and EPO levels were assessed.

RESULTS

Among the 158 children with thalassemia, 52(32.9%) were diagnosed with alpha-thalassemia minor, 27(17.1%) with HbH disease, 59(37.4%) with beta-thalassemia minor, 13(8.2%) with beta-thalassemia major, and 7(4.4%) with combining alpha beta thalassemia. The SF levels in children with HbH disease or beta-thalassemia major were significantly higher than those in the other thalassemia groups (P<0.01). The sTfR levels in children with beta-thalassemia major were the highest when compared with those in the other thalassemia groups (P<0.05). The EPO levels in children with beta-thalassemia major were also the highest when compared with those in the other thalassemia groups (P<0.01). There was a negative correlation between hemoglobin and EPO levels in children with HbH disease (r=-0.656, P<0.01) and beta-thalassemia major (r=-0.641; P<0.05).

CONCLUSIONS

The status of iron metabolism and erythropoietic proliferation is different in children with different genotypes of thalassemia. A combined measurement of SF, sTfR and EPO may reflect the status of erythropoietic proliferation.

[Changes of iron metabolism indices in children with various genotypes of thalassema]

OBJECTIVE

To study the value of iron metabolism indices, serum iron (SI), total iron blinding capacity (TIBC) and transferring (Tf), in thalassema.

METHODS

The serum samples from 9 children with silent alpha thalassema, 56 with standard alpha thalassema, 26 with HbH disease, 40 with beta+ thalassema, 56 with beta0 thalassema, 45 with iron deficiency anemia (IDA) and 70 healthy children were detected for SI, TIBC and Tf levels.

RESULTS

The SI level increased (p<0.01), while the TIBC level decreased significantly in the beta0 thalassema group compared with those in the other groups (p<0.05 or 0.01), but the Tf level was not different. The Tf level of both the silent alpha thalassema and the standard alpha thalassema groups was statistically lower than that of the healthy group (p<0.01), but the levels of SI and TIBC were similar to the healthy group. Though the SI level of the HbH disease group was similar to the healthy group, the TIBC and Tf levels were statistically lower (p<0.01).

CONCLUSIONS

Compared with Tf, SI and TIBC are better indices for monitoring iron loading in children with thalassema. The increased SI level and decreased TIBC level are two indices for the diagnosis of beta(0) thalassema in children with cellule anaemia.

Role of T2* magnetic resonance in monitoring iron chelation therapy

The monitoring of chelation therapy is a very important part of the management of transfusion-dependent patients. Classical methods of monitoring iron loading are either unreliable or unable to detect important myocardial siderosis which can predispose to the development of cardiac complications such as heart failure. The development of the T2* technique using cardiovascular magnetic resonance has allowed clinicians to have a reliable method for measuring cardiac iron to guide chelation therapy. T2* can identify early those patients who are at risk of developing cardiac complications, enabling personalised, tailored therapy to avoid potential problems.

Hb Hope [β136(H14)Gly→Asp (GGT→GAT)]: Interactions with Hb S [β6(A3)Glu→Val (GAG→GTG)], Other Variant Hemoglobins and Thalassemia

Hb Hope [beta136(H14)Gly-->Asp (GGT-->GAT)] was first described in an African-American family in 1965. Since then, it has been found in combination with several different globin gene mutations in many other families of divergent ethnic backgrounds. The basis for its relatively frequent occurrences remains unexplained. This variant hemoglobin (Hb) is mildly unstable and has reduced oxygen affinity, but is generally innocuous clinically. This variant Hb can present as a confounding factor in arriving at a correct diagnosis by either electrophoresis or high performance liquid chromatography (HPLC), particularly during the neonatal period. DNA-based diagnostics can help solve this potential problem.

Multislice multiecho T2* cardiac magnetic resonance for the detection of heterogeneous myocardial iron distribution in thalassaemia patients

The present study investigated myocardial T2* heterogeneity in thalassaemia major (TM) patients by cardiac magnetic resonance (CMR), to determine whether is related to inhomogeneous iron overload distribution. A total of 230 TM patients consecutively referred to our laboratory were studied retrospectively. Three short-axis views (basal, medium and apical) of the left ventricle (LV) were obtained by multislice multiecho T2* CMR. T2* segmental distribution was mapped on a 16-segment LV model. The level of heterogeneity of the T2* segmental distribution, evaluated by the coefficient of variation (CoV), was compared with that of a surrogate data set, to determine whether the inhomogeneous segmental distribution of T2* could be generated by susceptibility artefacts. Susceptibility artefacts offer an explanation for the T2* heterogeneity observed in patients without iron overload. In subjects with global T2* below the lower limit of the normal, T2* heterogeneity increased abruptly which could not be explained by artefactual effects. Some segmental T2* values were below and others above the limit of normal threshold (20 ms) in 104 (45%) TM patients. Among these patients, 74% showed a normal T2* global value. In conclusion, a true heterogeneity in the iron overload distribution may be present in TM patients. Heterogeneity seemingly appears in the borderline myocardial iron and stabilizes at moderate to severe iron burden.

Skin Iron Concentration: a Simple, Highly Sensitive Method for Iron Stores Evaluation in Thalassemia Patients

Iron overload is a potentially fatal complication in thalassemia patients. Accurate assessment of body iron is of utmost importance for these patients. The available methods for iron stores evaluation have limitations. We assessed biochemically the skin iron concentration (SIC) and determined the relation between the hepatic and skin iron level in thalassemia major patients to develop a simple, sensitive, quantitative measure of the body iron stores. Thirty-one cases with thalassemia major were assessed for iron overload. Liver and skin biopsies were performed for the patients and skin biopsies were taken from the 31 controls. The biopsies were subjected to biochemical assay of iron and histologic sections were examined. The SIC of the studied cases was significantly higher than that of the control group with a mean of 2.705 +/- 1.14 and 0.275 +/- 0.13 mg/g dry skin weight, respectively, p < 0.001. There was significant correlation between the SIC and the liver iron concentration (LIC) (r = 0.43, p = 0.01). The amount of liver iron is equivalent to [(3.5 x SIC) + 12.9]. With the use of this equation, we could reliably estimate an LIC value as high as 21.2 mg/g dry liver weight with a standard error of 4.07. Biochemical assay of the skin iron concentration is a reliable quantitative indicator of the body iron stores in patients with thalassemia major.

Evaluation of a web-based network for reproducible T2* MRI assessment of iron overload in thalassemia

PURPOSE

To build and evaluate a national network able to improve the care of thalassemia, a genetic disorder in haemoglobin synthesis often associated with iron accumulation in a variety of organs, due to the continuous blood transfusions.

METHODS

The MIOT (Myocardial Iron Overload in Thalassemia) network is constituted by thalassemia and magnetic resonance imaging (MRI) centers. Thalassemia centers are responsible for patient recruitment and collection of anamnestic and clinical data. MRI centers have been equipped with a standardized acquisition technique and an affordable workstation for image analysis. They are able to perform feasible and reproducible heart and liver iron overload assessments for a consistent number of thalassemia patients in a robust manner. All centers are linked by a web-based network, configured to collect and share patient data.

RESULTS

On 30th March 2008, 695 thalassemia patients were involved in the network. The completion percentage of the patient records in the database was 85+/-6.5%. Six hundred and thirteen patients (88%) successfully underwent MRI examination. Each MRI center had a specific absorption capacity that remained constant over time, but the network was capable of sustaining an increasing number of patients due to continuous enrollment of new centers. The patient's comfort, assessed as the mean distance from the patient home locations to the MRI centers, significantly increased during the network's evolution.

CONCLUSION

The MIOT network seems to be a robust and scalable system in which T2* MRI-based cardiac and liver iron overload assessment is available, accessible and reachable for a significant and increasing number of thalassemia patients in Italy (about 420 per year), reducing the mean distance from the patient locations to the MRI sites from 951km to 387km. A solid, wide and homogeneous database will constitute an important scientific resource, shortening the time scale for diagnostic, prognostic and therapeutical evidence-based research on the management of thalassemia disease.

Iron metabolism in heterozygotes for hemoglobin E (HbE), alpha-thalassemia 1, or beta-thalassemia and in compound heterozygotes for HbE/beta-thalassemia

BACKGROUND

Despite large populations carrying traits for thalassemia in countries implementing universal iron fortification, there are few data on the absorption and utilization of iron in these persons.

OBJECTIVE

We aimed to determine whether iron absorption or utilization (or both) in women heterozygous for beta-thalassemia, alpha-thalassemia 1, or hemoglobin E (HbE) differed from that in control subjects and compound HbE/beta-thalassemia heterozygotes.

DESIGN

In Thai women (n = 103), red blood cell indexes, iron status, non-transferrin-bound iron, and growth differentiation factor 15 were measured, and body iron was calculated. Fractional iron absorption was measured from meals fortified with isotopically labeled ((57)Fe) Fe sulfate, and iron utilization was measured by the infusion of ((58)Fe) Fe citrate.

RESULTS

Iron utilization was approximately 15% lower in alpha-thalassemia 1 or beta-thalassemia heterozygotes than in controls. When corrected for differences in serum ferritin, absorption was significantly higher in the alpha- and beta-thalassemia groups, but not the HbE heterozygotes, than in controls. HbE/beta-thalassemia compound heterozygotes had lower iron utilization and higher iron absorption and body iron than did controls. Nontransferrin-bound iron and growth differentiation factor 15 were higher in the compound heterozygotes, but not in the other groups, than in the controls.

CONCLUSIONS

In alpha-thalassemia 1 and beta-thalassemia heterozygotes with ineffective erythropoesis, dietary iron absorption is not adequately down-regulated, despite a modest increase in body iron stores. In populations with a high prevalence of these traits, a program of iron fortification could include monitoring for possible iron excess and for iron deficiency.

Role of iron in osteoporosis

Osteoporosis is a remarkably frequent complication of iron loading conditions such as thalassemia, sicklemia, African siderosis, hemochromatosis, smoking, alcoholism, HIV infection, and cessation of menstruation. The metal suppresses osteoblast formation of bone and may also stimulate osteoclast resorption of bone. Iron also inhibits anterior pituitary synthesis of gonadotrophs. This, in turn, results in depressed formation of gonadal hormones. The tendency of iron-loaded persons to become osteoporotic may be enhanced by gonadal hormone deficiency. Iron binding agents that could specifically withhold excess skeletal iron (and be excreted as the iron chelate) might have therapeutic utility.

Practical implications of liver and heart iron load assessment by T2*-MRI in children and adults with transfusion-dependent anemias

This study examined the relationship between hepatic and myocardial iron concentration, assessed by T2*-MRI in 66 patients (3-82 years) with transfusion-dependent anemias and thalassemia intermedia, to determine whether hepatic iron levels alone suffice for chelation adjustments. We found a poor correlation between hepatic and myocardial iron (r = 0.10, P = 0.43) and identified a subgroup (14%) with increased myocardial iron without a matched degree of hepatic hemosiderosis. Left ventricular ejection fraction was insensitive for detecting elevated myocardial iron. These findings were present in both adult and pediatric patients. We recommend therapeutic monitoring of iron burden by evaluation of both liver and myocardial iron with T2*-MRI.

Treatment of iron overload in thalassemia

Iron overload, characterized by excessive iron deposition, occurs commonly in patients with hereditary or refractory anemias such as beta-thalassemia major, sickle cell anemia, and myelodysplastic syndromes, whose anemia is managed with frequent blood transfusions. Without adequate iron chelation therapy, almost all patients with beta-thalassemia will accumulate potentially fatal iron levels. Myocardial siderosis and resulting cardiac complications are among the leading causes of death in such patients. Unfortunately, even with the administration of effective subcutaneous iron chelation therapy with desferrioxamine (DFO), over 50% of patients die before the age of 35 years, largely because of poor compliance with subcutaneous chelation regimens. Recently introduced oral chelation agents, deferiprone and deferasirox, are associated with higher compliance rates, and greater reductions in cardiac iron levels, than those achieved with DFO. This article reviews the pharmacologic properties and clinical efficacy of currently available iron chelation therapies in the management of transfusional chronic iron overload.

Assessment of cardiac and hepatic iron overload in thalassaemic patients by magnetic resonance: a four year observational study

In this study, we present results of the determination of cardiac and hepatic iron overload in patients with thalassaemia by means of a non-invasive method based on magnetic resonance. The procedure was applied for a period of four years to a group of patients followed in the Thalassemia Centre of our hospital. The gathered data were stratified to indicate groups of patients with mild, moderate and severe hepatic iron overload. We also studied cardiac iron overload and related it to the ejection fraction. In addition, we addressed the issue of replacement of the resonance equipment with a change in the intensity of the magnetic field from 1 to 1.5 T. The calibration on the new equipment was carried out using a set of MnCl2 standard solutions. The results demonstrated the possibility of using the algorithms reported in the literature and thus the "portability" of the procedure on equipment of the same type. The study has confirmed the usefulness of this non-invasive procedure for the monitoring of the iron load in patients with thalassaemia and the possibility of its use on resonance installations in clinical use.

Relationships between MR transverse relaxation parameters R*(2), R(2) and R'(2) and hepatic iron content in thalassemic mice at 1.5 T and 3 T

Assessment of hepatic iron concentration is important in the management of patients with thalassemia. The goal of this study was to investigate the relationships between the three MR transverse relaxation rates, R*(2), R(2) and R'(2), and hepatic iron content in a mouse model of thalassemia at 1.5 and 3 T field strengths. A GESFIDE (gradient-echo sampling of free induction decay and echo) pulse sequence was used to measure the three parameters efficiently in a single scan in a study examining the livers of normal and thalassemic mice, including a subgroup of the latter that were subjected to periodic transfusions. The results showed that R*(2), R(2) and R'(2) all correlated closely with liver iron concentration at both 1.5 T and 3 T, with correlation coefficients ranging from 0.72 to 0.79. High degrees of correlation (r = 0.93-0.99) were also observed among the three MR parameters at both field strengths. It can be concluded that the three rates could all be effective for assessing hepatic iron concentration and that imaging at higher fields may not offer any advantages over that at lower fields.

Fracture prevalence and relationship to endocrinopathy in iron overloaded patients with sickle cell disease and thalassemia

Transfusional iron overload leads to gonadal failure and low bone mass in patients with thalassemia (Thal). However, gonadal failure is rarely reported in transfused patients with sickle cell disease (SCD) and the literature regarding fracture prevalence in SCD is limited. The objective of this study was to assess self-reported fracture prevalence and its relationship to endocrinopathy in transfused Thal or SCD subjects and compare to non-transfused subjects with SCD (NonTxSCD). Eligibility was based on age> or =12 years and liver iron concentration> or =10 mg/g dry wt or serum ferritin> or =2000 ng/mL (Thal or TxSCD) or for NonTxSCD, ferritin<500 ng/mL. Data were collected by patient interview and chart review at 31 clinical centers in the U.S., Canada and the U.K. 152 subjects with Thal (52% Male; 25.6+/-0.7 years), 203 subjects with TxSCD (44% Male, 24.7+/-0.9 years: Mean+/-SE), and 65 NonTxSCD (50% Male, 22.2+/-1.3 years) were enrolled. Overall, male subjects with Thal were more likely to have sustained a fracture in their lifetime (51%) compared to TxSCD (28%) or NonTxSCD (32%) (p=0.005). There was no difference in fracture prevalence among women (Thal: 26%, TxSCD 17%, NonTxSCD: 16%). Fracture was most frequently reported in the upper extremities (53.3% of all fractures) while spine and pelvic fractures were relatively common for such a young cohort: 10.6%. Though overall fracture prevalence was not distinctly different from published healthy cohorts, fewer fractures occurred during the adolescent years. In multivariate analysis, the significant predictors of fracture prevalence were Thal diagnosis (Odds Ratio: 2.3; 1.2-4.6; 95%CI), male gender (OR: 2.6; 1.5-4.5), hypothyroidism (OR: 3.3; 1.1-9.8) and age (OR: 1.1; 1.03-1.08). These data suggest that despite similar iron burden, transfused patients with Thal are at greater risk for fracture than subjects with SCD. Male subjects with Thal and hypothyroidism are at particular risk for fracture, in contrast, transfused subjects with SCD had no greater risk of fracture compared to non-transfused SCD. Though ethnic differences in fracture risk cannot be ignored, endocrinopathy is rare in TxSCD which may also provide some protection from fracture.

Elevated F2-isoprostanes in thalassemic patients

This study was aimed at investigating oxidative stress in thalassemic patients by measurement of the oxidative damage biomarker, F(2)-isoprostanes (F(2)-IsoPs), using gas chromatography-mass spectrometry. The results showed that the mean value of urinary F(2)-IsoPs, normalized with creatinine, in the thalassemic group was significantly higher than that from healthy subjects (3.38+/-2.15 ng/mg creatinine vs 0.86+/-0.55 ng/mg creatinine, respectively), and the mean value of plasma total F(2)-IsoPs in the thalassemic group was also significantly higher than that from healthy subjects (0.39+/-0.15 ng/ml vs 0.18+/-0.03 ng/ml, respectively). Serum ferritin, erythrocyte superoxide dismutase (SOD), glutathione peroxidase, glutathione, and TBARS levels after treatment of erythrocytes with H(2)O(2) were also investigated, and serum ferritin and erythrocyte SOD levels were significantly higher in thalassemic patients. Our findings are consistent with oxidative stress in thalassemia patients.

Nature of non-transferrin-bound iron: studies on iron citrate complexes and thalassemic sera

Despite its importance in iron-overload diseases, little is known about the composition of plasma non-transferrin-bound iron (NTBI). Using 30-kDa ultrafiltration, plasma from thalassemic patients consisted of both filterable and non-filterable NTBI, the filterable fraction representing less than 10% NTBI. Low filterability could result from protein binding or NTBI species exceeding 30 kDa. The properties of iron citrate and its interaction with albumin were therefore investigated, as these represent likely NTBI species. Iron permeated 5- or 12-kDa ultrafiltration units completely when complexes were freshly prepared and citrate exceeded iron by tenfold, whereas with 30-kDa ultrafiltration units, permeation approached 100% at all molar ratios. A g = 4.3 electron paramagnetic resonance signal, characteristic of mononuclear iron, was detectable only with iron-to-citrate ratios above 1:100. The ability of both desferrioxamine and 1,2-dimethyl-3-hydroxypyridin-4-one to chelate iron in iron citrate complexes also increased with increasing ratios of citrate to iron. Incremental molar excesses of citrate thus favour the progressive appearance of chelatable lower molecular weight iron oligomers, dimers and ultimately monomers. Filtration of iron citrate in the presence of albumin showed substantial binding to albumin across a wide range of iron-to-citrate ratios and also increased accessibility of iron to chelators, reflecting a shift towards smaller oligomeric species. However, in vitro experiments using immunodepletion or absorption of albumin to Cibacron blue-Sepharose indicate that iron is only loosely bound in iron citrate-albumin complexes and that NTBI is unlikely to be albumin-bound to any significant extent in thalassemic sera.

Identification of Two New Synthetic Histone Deacetylase Inhibitors That Modulate Globin Gene Expression in Erythroid Cells from Healthy Donors and Patients with Thalassemia

We have identified two new histone deacetylase (HDAC) inhibitors (9 and 24) capable of inducing the expression of gamma-globin and/or beta-globin promoter-driven reporter genes in a synthetic model of Hb switch. Both compounds also increased, with different mechanisms, the gamma/(gamma+beta) ratio expressed in vitro by normal human erythroblasts. Compound 9 increased the levels of gamma-globin mRNA and the gamma/(gamma+beta) ratio (both by 2-fold). Compound 24 increased by 3-fold the level of gamma-globin and decreased by 2-fold that of beta-globin mRNA, increasing the gamma/(gamma+beta) ratio by 6-fold, and raising (by 50%) the cell HbF content. Both compounds raised the acetylation state of histone H4 in primary cells, an indication that their activity was mediated through HDAC inhibition. Compounds 9 and 24 were also tested as gamma/(gamma+beta) mRNA inducers in erythroblasts obtained from patients with beta(0) thalassemia. Progenitor cells from patients with beta(0) thalassemia generated in vitro morphologically normal proerythroblasts that, unlike normal cells, failed to mature in the presence of EPO and expressed low beta-globin levels but 10 times higher-than-normal levels of the alpha hemoglobin-stabilizing protein (AHSP) mRNA. Both compounds ameliorated the impaired in vitro maturation in beta(0) thalassemic erythroblasts, decreasing AHSP expression to normal levels. In the case of two patients (of five analyzed), the improved erythroblast maturation was associated with detectable increases in the gamma/(gamma+beta) mRNA ratio. The low toxicity exerted by compounds 9 and 24 in all of the assays investigated suggests that these new HDAC inhibitors should be considered for personalized therapy of selected patients with beta(0) thalassemia.

Noninvasive liver-iron measurements with a room-temperature susceptometer

Magnetic susceptibility measurements on the liver can quantify iron overload accurately and noninvasively. However, established susceptometer designs, using superconducting quantum interference devices (SQUIDs) that work in liquid helium, have been too expensive for widespread use. This paper presents a less expensive liver susceptometer that works at room temperature. This system uses oscillating magnetic fields, which are produced and detected by copper coils. The coil design cancels the signal from the applied field, eliminating noise from fluctuations of the source-coil current and sensor gain. The coil unit moves toward and away from the patient at 1 Hz, cancelling drifts due to thermal expansion of the coils. Measurements on a water phantom indicated instrumental errors less than 30 microg of iron per gram of wet liver tissue, which is small compared with other errors due to the response of the patient's body. Liver-iron measurements on eight thalassemia patients yielded a correlation coefficient r = 0.98 between the room-temperature susceptometer and an existing SQUID. These results indicate that the fundamental accuracy limits of the room-temperature susceptometer are similar to those of the SQUID.

Artemisinin effectiveness in erythrocytes is reduced by heme and heme-containing proteins

Artemisinin loses its antimalarial activity on prolonged exposure to erythrocytes, especially alpha-thalassemic erythrocytes. In this report, we show that the major artemisinin-inactivating factor in cytosol of normal erythrocytes was heat-labile but a heat-stable factor from alpha-thalassemic cells also played a significant role in reducing artemisinin effectiveness, which was shown to be heme released from hemoglobin (Hb). Studies of fractionated lysate from genetically normal erythrocytes revealed that the protein fraction with molecular weight greater than 100 kDa was capable of reducing artemisinin effectiveness more readily than lower molecular weight fraction. Catalase and Hb A, but not selenoprotein glutathione peroxidase, were capable of reducing artemisinin effectiveness. Hemin (ferriprotoporphyrin IX) also reduced artemisinin effectiveness in a concentration- and time-dependent manner. It is concluded that heme and heme-containing proteins in erythrocyte are largely responsible for reducing artemisinin effectiveness and may contribute to resistance of Plasmodium falciparum infecting alpha-thalassemic erythrocytes observed in vitro.

Black-blood T2* technique for myocardial iron measurement in thalassemia

PURPOSE

To compare the effectiveness and reproducibility of a new black-blood sequence vs. a conventional bright-blood gradient-echo T2* sequence for myocardial iron overload measurement in thalassemia.

MATERIALS AND METHODS

Twenty thalassemia patients were studied. Black-blood sequence images were acquired in diastole after a double inversion recovery (DIR) preparation pulse. Bright-blood sequence images were acquired in both early systole and late diastole. The data were randomized and the T2* analysis was performed blindly by two independent observers.

RESULTS

The T2* values from the black-blood sequence were comparable to those of the conventional bright-blood sequence (25.7 +/- 12.9 msec vs. 26.4 +/- 14.2 msec in early systole, P = 0.44; and 25.2 +/- 13.1 msec in late diastole, P = 0.41). The coefficient of variation (CV) for black-blood image T2* analysis was 4.1% compared with 8.9% (early systole P = 0.03) and 7.8% (late diastole P = 0.05) for bright-blood image analysis.

CONCLUSION

The black-blood T2* technique yields high-contrast myocardial images, provides clearly depicted myocardial borders, and avoids blood signal contamination of the myocardium while yielding improvements in interobserver variability.

Belgrade rats display liver iron loading

Patients with mutations in divalent metal transporter-1 (DMT1), an intestinal nonheme iron transporter, suffer from microcytic anemia and hepatic iron loading. DMT1 is also mutated in Belgrade rats, an animal model with a thalassemic-like disorder of microcytic anemia with hyperferrinemia. However, aspects of hepatic iron loading in this genetic model are not well characterized. To more fully define the Belgrade rat's iron status, we compared the characteristics of homozygous (b/b) and heterozygous (b/+) rats fed an iron-supplemented diet for 3 wk postweaning. Dietary supplementation with ferrous iron improved the anemia of b/b rats insofar as hematocrits increased from 0.13 (21-d-old) to 0.31 (42-d-old). However, hematocrits remained significantly lower than those of age-matched b/+ rats (0.36 and 0.41 in 21- and 42-d-old heterozygotes, respectively, P < 0.05). Wright's staining of b/b red cells confirmed the hypochromic microcytic nature of Belgrade rats' anemia. The liver iron concentration of 42-d-old b/b rats was greater than in age-matched b/+ rats (5.97 vs. 2.24 mumol/g, P < 0.05). Whereas Perls' Prussian blue iron staining was evident in both periportal and centrilobular regions in 42-d-old b/b liver sections, no staining was observed in age-matched b/+ tissue sections. Quantitative real-time PCR analysis showed that expression of liver hepcidin mRNA in 42-d-old b/b rats was 3-fold greater than age-matched b/+ rats. These results indicate that, similar to human patients with DMT1 mutations, Belgrade rats also display hepatic iron loading. Our data suggest this condition arises from ineffective erythropoiesis.