Deferasirox reduces oxidative stress in patients with transfusion dependency

Deferasirox improved iron homeostasis and hematopoiesis in ovariectomized rats with iron accumulation

Menopause is a natural biological aging process characterized by the loss of ovarian follicular function and decrease estrogen levels. These hormonal fluctuations are associated with increased iron levels, which ultimately lead to iron accumulation. This study aims to investigate the effects of Deferasirox on iron homeostasis and hematopoiesis in ovariectomized rats with iron accumulation. Sixty-four female Wistar rats were divided into eight groups and underwent ovariectomy surgery to simulate menopause. Iron accumulation was induced through the injection of ammonium ferric citrate. Deferasirox was administered at doses of 50 mg/kg and 100 mg/kg. Hematological parameters, iron profile, antioxidant markers, oxidative stress indicators, histopathological evaluation of uterine, bone, bone marrow, liver, and spleen tissues, flow cytometric analysis of hematopoietic CD markers, and relative expression of Hamp, Pu.1, Gata1, and Gdf11 genes were analyzed. Deferasirox treatment improved histopathological changes in the uterine tissue of ovariectomized rats with iron accumulation, increased the number of white blood cells, and reduced serum iron levels, TIBC, ferritin, and transferrin saturation percentage. It also increased serum antioxidant capacity and reduced oxidative stress markers. Deferasirox had a positive effect on femur bone, hematopoietic cell count, volume of hematopoietic and adipose tissues in bone marrow, extramedullary hematopoiesis in the liver and spleen, and influenced the relative expression of Hamp, Pu.1, Gata1, and Gdf11 genes related to hematopoiesis and iron metabolism. In conclusion, Deferasirox effectively manages iron homeostasis and hematopoiesis in ovariectomized rats with iron accumulation and suppresses oxidative stress.

Circulating Iron in Patients with Sickle Cell Disease Mediates the Release of Neutrophil Extracellular Traps

Introduction

Neutrophils promote chronic inflammation and release neutrophil extracellular traps (NETs) that can drive inflammatory responses. Inflammation influences progression of sickle cell disease (SCD), and a role for NETs has been suggested in the onset of vaso-occlusive crisis (VOC). We aimed to identify factors in the circulation of these patients that provoke NET release, with a focus on triggers associated with hemolysis.

Methods

Paired serum and plasma samples during VOC and steady state of 18 SCD patients (HbSS/HbSβ0-thal and HbSC/HbSβ+-thal) were collected. Cell-free heme, hemopexin, and labile plasma iron have been measured in the plasma samples of the SCD patients. NETs formation by human neutrophils from healthy donors induced by serum of SCD patients was studied using confocal microscopy and staining for extracellular DNA using Sytox, followed by quantification of surface coverage using ImageJ.

Results

Eighteen patients paired samples obtained during VOC and steady state were available (11 HbSS/HbSβ0-thal and 7 HbSC/HbSβ+-thal). We observed high levels of systemic heme and iron, concomitant with low levels of the heme-scavenger hemopexin in sera of patients with SCD, both during VOC and in steady state. In our in vitro experiments, neutrophils released NETs when exposed to sera from SCD patients. The release of NETs was associated with high levels of circulating iron in these sera. Although hemin triggered NET formation in vitro, addition of hemopexin to scavenge heme did not suppress NET release in SCD sera. By contrast, the iron scavengers deferoxamine and apotransferrin attenuated NET formation in a significant proportion of SCD sera.

Discussion

Our results suggest that redox-active iron in the circulation of non-transfusion-dependent SCD patients activates neutrophils to release NETs, and hence, exerts a direct pro-inflammatory effect. Thus, we propose that chelation of iron requires further investigation as a therapeutic strategy in SCD.

Influence of iron- and zinc-chelating agents on neutrophil extracellular trap formation

Release of neutrophil extracellular traps (NETs) is one of the neutrophils’ mechanisms involved in the response to infection. NETs are released from the cell in response to a biological or synthetic stimulus to entrap, immobilize and kill pathogens. Metal ions and metal binding proteins were identified in the structure of NETs, but their role in NET release remains unclear. The aim of this study was to assess how lack of iron and zinc generated by ion sequestration using chelators affects NET release. Neutrophils were isolated from whole blood or buffy coats of healthy blood donors by density gradient centrifugation and incubated with zinc chelators: 20 µM N,N,N',N'-Tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), 40 µM diethylenetriaminepentaacetic acid (DTPA) or iron chelators: 400 µM deferoxamine mesylate salt (DFO) and 50 µM iminodiacetic acid (IDA). Next, 100 nM phorbol 12-myristate 13-acetate (PMA) was added to stimulate release of NETs. The amount of released DNA was measured by fluorometry and NETs were visualized by immunofluorescence microscopy. This study demonstrates that iron and zinc chelators are able to modulate NET release. Here we show that preincubation of neutrophils with TPEN and IDA inhibits NET release in cells stimulated with PMA. On the other hand, DFO stimulates NET release. Incubation of cells with DTPA does not affect release of NETs.

Deferasirox, an iron-chelating agent, alleviates acute lung inflammation by inhibiting neutrophil activation and extracellular trap formation

OBJECTIVE

Reactive oxygen species (ROS) production by neutrophils induces pulmonary endothelial cell damage and results in acute lung injury (ALI). We previously reported that deferasirox (DFS), an iron-chelating agent, inhibits the ROS production and neutrophil extracellular trap (NET) formation induced by phorbol myristate acetate and formylmethionylleucylphenylalanine in vitro. In the present study, we investigated the effects of DFS in vivo using a mouse model of lipopolysaccharide (LPS)-induced ALI.

METHODS

After DFS administration for 7 days, ALI was induced in mice by LPS via intratracheal administration.

RESULTS

LPS treatment induced neutrophil invasion in the lung tissues, along with NET formation and a significant increase in the quantity of double-stranded DNA in the bronchoalveolar lavage fluid, while pre-administered DFS inhibited these phenomena. However, alteration of neutrophil morphology in the cytoplasm in terms of shape and vacuolization was not inhibited by the pre-administration of DFS, possibly through ROS production.

CONCLUSIONS

DFS suppressed neutrophil invasion into lung tissues and reduced the double-stranded DNA content released by the neutrophils. These results suggest that DFS can potentially be used to prevent diseases related to neutrophil activation including ALI, thrombosis, and vascular endothelial dysfunction.

The Clinical Significance of Iron Overload and Iron Metabolism in Myelodysplastic Syndrome and Acute Myeloid Leukemia

Myelodysplasticsyndrome (MDS) and acute myeloid leukemia (AML) are clonal hematopoietic stem cell diseases leading to an insufficient formation of functional blood cells. Disease-immanent factors as insufficient erythropoiesis and treatment-related factors as recurrent treatment with red blood cell transfusions frequently lead to systemic iron overload in MDS and AML patients. In addition, alterations of function and expression of proteins associated with iron metabolism are increasingly recognized to be pathogenetic factors and potential vulnerabilities of these diseases. Iron is known to be involved in multiple intracellular and extracellular processes. It is essential for cell metabolism as well as for cell proliferation and closely linked to the formation of reactive oxygen species. Therefore, iron can influence the course of clonal myeloid disorders, the leukemic environment and the occurrence as well as the defense of infections. Imbalances of iron homeostasis may induce cell death of normal but also of malignant cells. New potential treatment strategies utilizing the importance of the iron homeostasis include iron chelation, modulation of proteins involved in iron metabolism, induction of leukemic cell death via ferroptosis and exploitation of iron proteins for the delivery of antileukemic drugs. Here, we provide an overview of some of the latest findings about the function, the prognostic impact and potential treatment strategies of iron in patients with MDS and AML.

Metal-free hydroarylation of the side chain carbon-carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

The metal-free reaction of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles with arenes in neat triflic acid (TfOH, CF3SO3H), both under thermal and microwave conditions, leads to 5-(2,2-diarylethyl)-3-aryl-1,2,4-oxadiazoles. The products are formed through the regioselective hydroarylation of the side chain carbon-carbon double bond of the starting oxadiazoles in yields up to 97%. According to NMR data and DFT calculations, N4,C-diprotonated forms of oxadiazoles are the electrophilic intermediates in this reaction.

Biodegradable Elastomers with Antioxidant and Retinoid-like Properties

Intimal hyperplasia (IH) is a type of scarring that involves complex pathophysiological responses of the vasculature to injury, including overproliferation and migration of vascular smooth muscle cells (VSMCs), adventitial fibroblasts, and the activation of macrophages. The objective of this research was to develop a biodegradable polymer with intrinsic properties that would combat the cellular processes that contribute to IH. Citric acid, 1,8-octanediol, and all-trans retinoic acid (atRA) were incorporated into a polyester network via a condensation reaction to form the thermoset poly(1,8-octamethylene-citrate-co-retinate) (POCR). POCR was chemically characterized and assessed for the presence of antioxidant and retinoidlike properties. ^HNMR and ATR-FTIR confirmed the incorporation of atRA into the backbone of the polymer network. POCR was able to scavenge radicals and inhibit lipid peroxidation. The proliferation and migration of vascular smooth muscle cells cultured on POCR were inhibited, whereas endothelial cell proliferation and migration were not. These results are consistent with the biological effects of atRA. These results are the first to demonstrate the synthesis of a polymer with intrinsic antirestenotic properties for potential use in the fabrication of vascular devices such as stents and vascular grafts.

HFE gene mutation and oxidative damage biomarkers in patients with myelodysplastic syndromes and its relation to transfusional iron overload: an observational cross-sectional study

OBJECTIVE

A relation between transfusional IOL (iron overload), HFE status and oxidative damage was evaluated.

DESIGN, SETTING AND PARTICIPANTS

An observational cross-sectional study involving 87 healthy individuals and 78 patients with myelodysplastic syndromes (MDS) with and without IOL, seen at University Hospital of the Federal University of Ceará, Brazil, between May 2010 and September 2011.

METHODS

IOL was defined using repeated measures of serum ferritin ≥1000 ng/mL. Variations in the HFE gene were investigated using PCR/restriction fragment length polymorphism (RFLP). The biomarkers of oxidative stress (plasmatic malonaldehyde (MDA), glutathione peroxidase (GPx) and superoxide dismutase (SOD)) were determined by spectrophotometry.

RESULTS

The HFE gene variations were identified in 24 patients (30.77%) and 5 volunteers (5.74%). The H63D variant was observed in 35% and the C282Y variant as heterozygous in 5% of patients with MDS with IOL. One patient showed double heterozygous variant (C282Y/H63D) and serum ferritin of 11,649 ng/mL. In patients without IOL, the H63D variant was detected in 29.34%. Serum MDA levels were highest in patients with MDS with IOL, with a significant difference when compared with patients without IOL and healthy volunteers, pointing to the relationship between IOL and oxidative stress. The GPx and SOD were also significantly higher in these patients, indicating that lipid peroxidation increase was followed by an increase in antioxidant capacity. Higher ferritin levels were observed in patients with HFE gene variation. 95.7% of patients with MDS with the presence of HFE gene variations had received more of 20 transfusions.

CONCLUSIONS

We observed a significant increase in MDA levels in patients with MDS and IOL, suggesting an increased lipid peroxidation in these patients. The accumulation of MDA alters the organisation of membrane phospholipids, contributing to the process of cellular degeneration. Results show that excess iron intensifies the process of cell damage through oxidative stress.

TRIAL REGISTRATION NUMBER

Local Ethics Committee (licence 150/2009).

Stimuli-responsive electrodes detect oxidative stress and liver injury

A digital point-of-care biosensor for measuring reactive oxygen species is presented based on novel reactive oxygen species responsive polymer-based electrodes. The biosensor is able to detect a drug-induced liver injury by monitoring the oxidative stress in the blood.

Diagnostic and therapeutic approach for acute paraquat intoxication

Paraquat (PQ) has known negative human health effects, but continues to be commonly used worldwide as a herbicide. Our clinical data shows that the main prognostic factor is the time required to achieve a negative urine dithionite test. Patient survival is a 100% when the area affected by ground glass opacity is <20% of the total lung volume on high-resolution computed tomography imaging 7 days post-PQ ingestion. The incidence of acute kidney injury is approximately 50%. The average serum creatinine level reaches its peak around 5 days post-ingestion, and usually normalizes within 3 weeks. We obtain two connecting lines from the highest PQ level for the survivors and the lowest PQ level among the non-survivors at a given time. Patients with a PQ level between these two lines are considered treatable. The following treatment modalities are recommended to preserve kidney function: 1) extracorporeal elimination, 2) intravenous antioxidant administration, 3) diuresis with a fluid, and 4) cytotoxic drugs. In conclusion, this review provides a general overview on the diagnostic procedure and treatment modality of acute PQ intoxication, while focusing on our clinical experience.

Engineering biodegradable polyester elastomers with antioxidant properties to attenuate oxidative stress in tissues

Oxidative stress plays an important role in the limited biological compatibility of many biomaterials due to inflammation, as well as in various pathologies including atherosclerosis and restenosis as a result of vascular interventions. Engineering antioxidant properties into a material is therefore a potential avenue to improve the biocompatibility of materials, as well as to locally attenuate oxidative stress-related pathologies. Moreover, biodegradable polymers that have antioxidant properties built into their backbone structure have high relative antioxidant content and may provide prolonged, continuous attenuation of oxidative stress while the polymer or its degradation products are present. In this report, we describe the synthesis of poly(1,8-octanediol-co-citrate-co-ascorbate) (POCA), a citric-acid based biodegradable elastomer with native, intrinsic antioxidant properties. The in vitro antioxidant activity of POCA as well as its effects on vascular cells in vitro and in vivo were studied. Antioxidant properties investigated included scavenging of free radicals, iron chelation and the inhibition of lipid peroxidation. POCA reduced reactive oxygen species generation in cells after an oxidative challenge and protected cells from oxidative stress-induced cell death. Importantly, POCA antioxidant properties remained present upon degradation. Vascular cells cultured on POCA showed high viability, and POCA selectively inhibited smooth muscle cell proliferation, while supporting endothelial cell proliferation. Finally, preliminary data on POCA-coated ePTFE grafts showed reduced intimal hyperplasia when compared to standard ePTFE grafts. This biodegradable, intrinsically antioxidant polymer may be useful for tissue engineering application where oxidative stress is a concern.

Impact of iron overload and potential benefit from iron chelation in low-risk myelodysplastic syndrome

Myelodysplastic syndromes (MDSs) are a group of heterogeneous clonal bone marrow disorders characterized by ineffective hematopoiesis, peripheral blood cytopenias, and potential for malignant transformation. Lower/intermediate-risk MDSs are associated with longer survival and high red blood cell (RBC) transfusion requirements resulting in secondary iron overload. Recent data suggest that markers of iron overload portend a relatively poor prognosis, and retrospective analysis demonstrates that iron chelation therapy is associated with prolonged survival in transfusion-dependent MDS patients. New data provide concrete evidence of iron's adverse effects on erythroid precursors in vitro and in vivo. Renewed interest in the iron field was heralded by the discovery of hepcidin, the main serum peptide hormone negative regulator of body iron. Evidence from β-thalassemia suggests that regulation of hepcidin by erythropoiesis dominates regulation by iron. Because iron overload develops in some MDS patients who do not require RBC transfusions, the suppressive effect of ineffective erythropoiesis on hepcidin may also play a role in iron overload. We anticipate that additional novel tools for measuring iron overload and a molecular-mechanism-driven description of MDS subtypes will provide a deeper understanding of how iron metabolism and erythropoiesis intersect in MDSs and improve clinical management of this patient population.

Status of systemic oxidative stress during therapeutic hypothermia in patients with post-cardiac arrest syndrome

Therapeutic hypothermia (TH) is thought to be due to the downregulation of free radical production, although the details of this process remain unclear. Here, we investigate changes in oxidative stress and endogenous biological antioxidant potential during TH in patients with post-cardiac arrest syndrome (PCAS). Nineteen PCAS patients were enrolled in the study. Brain temperature was decreased to the target temperature of 33°C, and it was maintained for 24 h. Patients were rewarmed slowly (0.1°C/h, <1°C/day). The generation of reactive oxygen metabolites (ROMs) was evaluated in plasma samples by d-ROM test. Plasma antioxidant capacity was measured by the biological antioxidant potential (BAP) test. Levels of d-ROMs and BAP levels during the hypothermic stage (33°C) were suppressed significantly compared with pre-TH induction levels (P < 0.05), while both d-ROM and BAP levels increased with rewarming (33-36°C) and were correlated with brain temperature. Clinical monitoring of oxidative stress and antioxidant potential is useful for evaluating the redox state of patients undergoing TH after PCAS. Additional therapy to support the antioxidant potential in the rewarming stage following TH may reduce some of the observed side effects associated with the use of TH.