Oxidative stress in β-thalassaemia and sickle cell disease

Antioxidant nutrients and hemolysis in sickle cell disease

Hemolysis is one of the main pathophysiological characteristics of sickle cell disease (SCD) and might cause or could be the result of oxidative stress. Antioxidants are studied in SCD due to their potential to ensure redox balance and minimize deleterious effects on erythrocyte membranes. The objective of this systematic review was to evaluate the efficacy of antioxidant nutrient supplementation on reducing hemolysis in SCD patients through randomized clinical trials. We conducted our study according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses and the Cochrane Handbook for Systematic Reviews of Interventions investigating whether antioxidants could improve the hemolytic status of SCD patients. This study included 587 articles published until April 2020. We reduced this pool to 12 articles by excluding duplicates, reviews, comments, and studies with non-human subjects. Omega-3 fatty acids, vitamin A, and zinc were the antioxidants that reportedly improved the indirect hemolysis parameters such as hemoglobin, hematocrit, mean corpuscular volume, or red blood cells. High-dose vitamin C and E supplementation worsened hemolysis, causing increased reticulocytes, lactate dehydrogenase, indirect bilirubin, and haptoglobin. More intervention studies especially high-quality controlled randomized clinical trials are needed to investigate the effects of antioxidant nutrients in reducing hemolysis in SCD.

Genetic Regulation of Redox Balance in β-Thalassemia Trait

β-Thalassemia (β-thal) trait is a heterogeneous group of genetic defects leading to decreased β-globin production, ineffective erythropoiesis, and oxidative stress. The aim is to evaluate the cytoprotective response, at transcriptional and systemic levels, of the variations of global redox balance in β-thal trait patients. Sixty-six subjects (40 healthy and 26 with β-thal trait) were analyzed at the Universidad Nacional de Tucumán, Tucumán, Argentina, between 2016 and 2017. The following parameters were evaluated: complete blood count, iron status, hemoglobin (Hb) electrophoresis, Hb A₂, thiobarbituric acid reactive species (TBARS), serum catalase (CAT), and superoxide dismutase (SOD) activity, FOXO3a, NRF2, SOD, PRDX2, CAT, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) gene expression. The β-thal trait group showed a decrease in Hb levels, MCV, and MCH with higher TBARS levels. The SOD activity was significantly increased by 32.0% in β-thal trait patients respect to the control group. Relative expression of NRF2 was 4.7-fold higher in β-thal trait than in the control group, while FOXO3a expression was similar in both groups. The SOD, PRDX2, and proinflammatory cytokines transcriptional expression was significantly upregulated in β-thal trait patients. This is the first study on the genetic regulation of redox balance in β-thal trait patients in which interesting modifications were observed in the transcript levels of some redox regulators that could be associated with changes in the erythrocyte proteome in this disorder. A better understanding of the pathophysiological mechanisms present in these heterozygous patients would allow adequate therapy in situations such as growth, pregnancy, or high performance sports, favoring a personalized treatment.

Sickle cell disease as a vascular disorder

INTRODUCTION

In sickle cell disease (SCD), hemoglobin S (HbS) red blood cells (RBCs) are characteristically deformed and inflexible. Often breaking down in the circulation, they exhibit increased adhesive properties with the endothelium and activated neutrophils and platelets, increasing the risk of occlusion of the microcirculation. SCD is categorized into two sub-phenotypes: hyperhemolytic, associated with priapism, leg ulcers, pulmonary hypertension, and stroke, and high hemoglobin/viscosity, which may promote vaso-occlusion-associated pain, acute chest syndrome, and osteonecrosis.

AREAS COVERED

The sub-phenotypes are not completely distinct. Hemolysis may trigger vaso-occlusion, contributing to vascular complications. Targeting P-selectin, a key mediator of cross-talk between hyperhemolysis and vaso-occlusion, may be beneficial for vascular and vaso-occlusion-associated complications. English-language articles from PubMed on the topic of SCD and vaso-occlusive crises (VOCs) were reviewed from 1 January 2000 to 1 January 2019 using the search terms 'sickle cell disease,' 'vaso-occlusive crises,' and 'selectin.'

EXPERT OPINION

Besides targeting P-selectin, other strategies to counter VOCs and RBC sickling are being pursued. These include platelet inhibition to counter aggregation, intercellular adhesion, and thrombosis during VOCs; gene therapy to correct the homozygous missense mutation in the β-globin gene, causing polymerization of HbS; L-glutamine, possibly reducing oxidative stress in sickled RBCs; and fetal hemoglobin inducers.

Placental histopathology in sickle cell disease: A descriptive and hypothesis-generating study

INTRODUCTION

Abnormal placental development is a unifying factor amongst many adverse pregnancy outcomes (APOs) in Sickle Cell Disease (SCD). Our aim was to describe placental histopathologic findings in women with SCD and their relationship with APOs, and to explore the association between antenatal sonographic findings and placental pathology.

METHODS

Retrospective single-centre case series of all pregnant women with SCD (January 2000-December 2017), pregnancy beyond 20 weeks' gestation, and available placenta histopathology. APOs included intrauterine fetal death, early neonatal death, preterm birth, small for gestational age, and hypertensive disorders of pregnancy. Review of images for mid-pregnancy ultrasound and one proximal to delivery was completed, blinded to clinical outcomes and histopathology results. Gross and histopathologic findings were reviewed and characterized per published classification.

RESULTS

Of 72 placentas, abnormalities were present in 69%, with Maternal Vascular Malperfusion (MVM) noted in 40%. APOs were encountered in 61% overall and in 79% of those with MVM. Neither SCD genotype nor severe maternal anemia had an influence on histopathologic placental features. Presence of high-resistance uterine artery waveforms at mid-trimester ultrasound was strongly associated with APOs and with abnormal findings on placental histopathology, most notably MVM. MVM was strongly associated with small for gestational age infants, preterm birth, and stillbirth.

DISCUSSION

MVM is the predominant lesion in placentas of women with SCD and is strongly associated with APOs. Mid-trimester ultrasound can identify a subset of women at risk. Future research into advanced imaging modalities to aid in antenatal diagnosis alongside investigations of potentially beneficial therapies is needed.

Phytocomponents from Anacardium occidentale, Psidium guajava, and Terminalia catappa altered membrane osmotic stability of sickle erythrocytes

Background

The present study identified, quantified, and characterized the combinations of phytocomponents from fractionated leaf extracts of Anacardium occidentale, Psidium guajava, and Terminalia catappa that stabilized sickle erythrocyte membrane against osmotic stress, or otherwise, using standard chromatographic-spectrophotometric techniques, namely GC-MS, FT-IR, and UV-visible systems.

Results

The percentage hemolysis of the control sample, in 0.9 g/100 mL NaCl, was 35.08 ± 11.64%, whereas those of the samples containing 40 mg/100 mL, 60 mg/100 mL, and 80 mg/100 mL of ethylacetate extracts of T. catappa ranged between 31.82 ± 8.32 and 39.18 ± 6.94%. Ethylacetate extract of T. catappa contained comparative high quantities of hexadecanoic acid methyl ester, 9,11-octadecadienoic acid, methyl ester, (E, E)-, trans-13-octadecenoic acid methyl ester, and methyl stearate. FT-IR and UV-visible spectra showed that ethylacetate extract of T. catappa contained aromatic compounds as well as nitro-compounds, phenolics, and esters.

Conclusion

To mention but a few, the combinations of major phytocomponents that stabilized sickle erythrocyte membrane against osmotic stress were hexadecanoic acid, methyl ester, 11-octadecenoic acid, methyl ester, dibutyl phthalate, pentacosane, trans-13-octadecenoic acid, methyl ester, whereas the minor phytocomponents include methyl tetradecanoate, methoxyacetic acid, 3-pentadecyl ester, methyl stearate, hexadecanoic acid, isoxazole, 4,5-dimethyl-.

Proteomic Studies for the Investigation of γ-Globin Induction by Decitabine in Human Primary Erythroid Progenitor Cultures

Reactivation of γ-globin is considered a promising approach for the treatment of β-thalassemia and sickle cell disease. Therapeutic induction of γ-globin expression, however, is fraught with lack of suitable therapeutic targets. The aim of this study was to investigate the effects that treatment with decitabine has on the proteome of human primary erythroid cells from healthy and thalassemic volunteers, as a means of identifying new potential pharmacological targets. Decitabine is a known γ-globin inducer, which is not, however, safe enough for clinical use. A proteomic approach utilizing isobaric tags for relative and absolute quantitation (iTRAQ) analysis, in combination with high-pH reverse phase peptide fractionation followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), was employed to investigate the effects of decitabine treatment. Bioinformatics analysis making use of the Database for Annotation, Visualization and Integrated Discovery (DAVID) was employed for functional annotation of the 192 differentially expressed proteins identified. The data are available via ProteomeXchange with identifier PXD006889. The proteins fall into various biological pathways, such as the NF-κB signaling pathway, and into many functional categories including regulation of cell proliferation, transcription factor and DNA binding, protein stabilization, chromatin modification and organization, and oxidative stress proteins.

Decreased erythrocyte binding of Siglec-9 increases neutrophil activation in sickle cell disease

Oxidative stress and inflammation promote vaso-occlusion in sickle cell disease (SCD). CD33-related Sialic acid-binding immunoglobulin-type lectins (CD33rSiglecs) are cell surface proteins that recognize sialic acids inhibit innate immune cell functions. We have shown that Siglec-9 on human neutrophils interact with erythrocyte sialic acids (prominently glycophorin-A (GYPA) to suppress neutrophil reactive oxygen species (ROS). We hypothesized that altered sickle erythrocyte membrane sialic acid leads to decreased Siglec-9 binding capability, and thus a decreased neutrophil oxidative burst. SS erythrocytes express significantly more sialic acid than AA erythrocytes (p = 0.02). SS erythrocytes displayed significantly less Siglec-9-Fc binding 39% ± 11 (mean ± SEM) compared to AA erythrocytes 78% ± 5 (p = 0.009). Treatment of AA erythrocytes with sialidase to remove sialic acid decreased binding to 3% ± 7.9 (p ≤ 0.001). When freshly isolated neutrophils were incubated with AA erythrocytes, neutrophils achieved 16% ± 6 of the oxidative burst exhibited by a stimulated neutrophil without erythrocytes. In contrast, neutrophils incubated with SS erythrocytes achieved 47% ± 6 of the oxidative burst (AA versus SS, p = 0.03). Stimulated neutrophils incubated with AA erythrocytes showed minimal NET formation while with SS erythrocytes NETs increased. SS erythrocytes are deficient in binding to neutrophil Siglec-9 which may contribute to the increased oxidative stress in SCD.

Oral ferroportin inhibitor ameliorates ineffective erythropoiesis in a model of β-thalassemia

β-Thalassemia is a genetic anemia caused by partial or complete loss of β-globin synthesis, leading to ineffective erythropoiesis and RBCs with a short life span. Currently, there is no efficacious oral medication modifying anemia for patients with β-thalassemia. The inappropriately low levels of the iron regulatory hormone hepcidin enable excessive iron absorption by ferroportin, the unique cellular iron exporter in mammals, leading to organ iron overload and associated morbidities. Correction of unbalanced iron absorption and recycling by induction of hepcidin synthesis or treatment with hepcidin mimetics ameliorates β-thalassemia. However, hepcidin modulation or replacement strategies currently in clinical development all require parenteral drug administration. We identified oral ferroportin inhibitors by screening a library of small molecular weight compounds for modulators of ferroportin internalization. Restricting iron availability by VIT-2763, the first clinical stage oral ferroportin inhibitor, ameliorated anemia and the dysregulated iron homeostasis in the Hbbth3/+ mouse model of β-thalassemia intermedia. VIT-2763 not only improved erythropoiesis but also corrected the proportions of myeloid precursors in spleens of Hbbth3/+ mice. VIT-2763 is currently being developed as an oral drug targeting ferroportin for the treatment of β-thalassemia.

Hemorheological Alterations and Oxidative Damage in Sickle Cell Anemia

Sickle cell anemia (SCA) is the most common hereditary disorder of hemoglobin (Hb) characterized by a mutation in the β globin gene, which leads to synthesis of HbS a hemoglobin which, under hypoxic conditions, gels and leading to the sickling of the red blood cells (RBC). The dehydration of the RBC increases the concentration of the intracellular Hb with an increase in the internal viscosity and consequently a decrease in the erythrocyte deformability. Sickle red blood cells due to their difficulty to flow through the microcirculation cause frequent vaso-occlusive episodes, tissue ischemia, and infarctions. Moreover, the reduced RBC deformability causes cell fragility leading to hemolysis and recently a key role of hemolysis and oxidative stress in the development of vascular dysfunction has been demonstrated. The aim of this study was to evaluate the hemorheological profiles of patients with SCA in order to point out new indices of vascular impairment, and to characterize the membrane oxidative damage of sickled RBC. Blood viscosities, erythrocyte aggregation, and viscoelastic profiles of SCA patients were determined, and the RBC oxidative damage was investigated by comparing metabolic capability and RBC membrane proteins from SCA patients with and without transfusion dependence. The hemorheological profile of SCA subjects demonstrated high blood viscosity, increased RBC aggregation, and decreased RBC deformability. These impaired flow properties were associated with RBC membrane protein oxidation, with degradation of spectrin and increased membrane-bound globin. The comparison between SCA patients with and without transfusion dependence showed metabolic and structural RBC oxidative damage significantly different.

The association of HBB-related significant hemoglobinopathies and low fetal fraction on noninvasive prenatal screening for fetal aneuploidy

Objectives: HBB-related significant hemoglobinopathies have been anecdotally associated with low fetal fraction on noninvasive prenatal screening (NIPS). We sought to compare the difference in fetal fraction using NIPS in women with HBB-related significant hemoglobinopathies (HSH) and women with normal hemoglobin.Study design: This is a retrospective case-control study. Cases were women with a diagnosis of HSH using NIPS from a commercial laboratory. The comparison group was women with hemoglobin AA from a tertiary care center database. We tested for differences in median fetal fraction using quantile regression analysis, adjusting for maternal body weight and gestational age.Results: This study includes 35 women with clinically significant HSH and a comparison group of 636 women with hemoglobin AA. Adjusting for gestational age and body weight, the median fetal fraction was 4.1 point lower in the HSH than in the comparison group (β - 4.1; 95% -5.7 to -2.5, p < .05). The rate of no-calls due to low fetal fraction was significantly higher in the clinically significant HSH group than in the comparison group [HSH: n = 9/35, 25.7% versus comparison: n = 32/636, 5.0% (p < .001)].Conclusion: Women with HSH were more likely to have a lower fetal fraction and ultimately a five-fold higher no-call rate. What's already known about this topic?Low fetal fraction is one of the most common causes of no-call result in noninvasive prenatal screeningHigh maternal weight, early gestational age and fetal aneuploidies are associated with low fetal fraction What does this study add?HBB-related significant hemoglobinopathies are associated with low fetal fractionReduction in fetal fraction due to HBB-related significant hemoglobinopathies may also result in higher no-call rate.

Sickle Cell Trait Induces Oxidative Damage on Plasmodium falciparum Proteome at Erythrocyte Stages

The presence of hemoglobin A-S (HbAS) in erythrocytes has been related to the high production of reactive oxygen species (ROS) and an increased in intracellular oxidative stress that affects the progress of Plasmodium erythrocytic cycle life and attenuates its serious clinical symptoms. Nevertheless, oxidative effects on P. falciparum proteome across the intraerythrocytic cycle in the presence of HbAS traits have not been described yet. Here, an immune dot-blot assay was used to quantify the carbonyl index (C.I) on P. falciparum 3D7 proteome at the different asexual erythrocytic stages. Protein carbonylation on parasites cultivated in erythrocytes from two donors with HbAS increased 5.34 ± 1.42 folds at the ring stage compared to control grown in hemoglobin A-A (HbAA) red blood cells. Whereas at trophozoites and schizonts stages were augmented 2.80 ± 0.52 and 3.05 ± 0.75 folds, respectively. Besides proteins involved in processes of the stress response, recognition and invasion were identified from schizonts carbonylated bands by combining SDS-PAGE with MALDI-TOF-TOF analysis. Our results reinforce the hypothesis that such oxidative modifications do not appear to happen randomly, and the sickle cell trait affects mainly a small fraction of parasite proteins particularly sensitive to ROS.

Thiol Disulfide Homeostasis and Ischemia-modified Albumin Level in Children With Beta-Thalassemia

OBJECTIVE

It is well known that increased oxidative stress leads to tissue damage in beta-thalassemia (β-thal) patients. Thiols are one of the most important antioxidant agents, and thiol/disulfide (SH/SS) homeostasis is a novel oxidative stress marker. This study aimed to investigate the relationship of thiol levels, SH/SS homeostasis, and ischemia-modified albumin (IMA) in patients with β-thal.

MATERIALS AND METHODS

A hundred transfusion-dependent β-thal patients and 41 healthy controls were included in the study.

RESULTS

Native thiol, total thiol, disulfide, catalase, and IMA levels were significantly higher in the β-thal group compared with the control group (P<0.02). There were no correlation between serum ferritin level and SH/SS homeostasis, and weak positive correlations were found between serum ferritin and IMA (r=0.242, P=0.022).

CONCLUSIONS

Our study results suggest that antioxidant systems try to compensate for peroxidative damage in the patients' group and serum IMA level was found increased because of increased oxidative status. To the best of our knowledge, there has been no report evaluating plasma dynamic SH/SS homeostasis in β-thal patients.

Selenium Status and Hemolysis in Sickle Cell Disease Patients

Sickle cell disease (SCD) is a genetic hemoglobinopathy characterized by chronic hemolysis. Chronic hemolysis is promoted by increased oxidative stress. Our hypothesis was that some antioxidant micronutrients (retinol, tocopherol, selenium, and zinc) would be determinant factors of the degree of hemolysis in SCD patients. We aimed to investigate the nutritional adequacy of these antioxidants and their relationships to hemolysis. The study included 51 adult SCD patients regularly assisted in two reference centers for hematology in the State of Rio de Janeiro, Brazil. Serum concentrations of retinol, alpha-tocopherol, selenium, and zinc were determined by high-performance liquid chromatography or atomic absorption spectrometry. Hematological parameters (complete blood count, reticulocyte count, hemoglobin, direct and indirect bilirubin, total bilirubin, lactate dehydrogenase) and inflammation markers (leukocytes and ultra-sensitive C-reactive protein) were analyzed. A linear regression model was used to test the associations between the variables. Most patients presented selenium deficiency and low selenium consumption. Linear regression analysis showed that selenium is the main determinant of hemolysis among the antioxidant nutrients analyzed. Thus, data from this study suggest that the nutritional care protocols for patients with SCD should include dietary sources of selenium in order to reduce the risk of hemolysis.

Oxidative Stress in β-Thalassemia

Cell oxidative status, which represents the balance between oxidants and antioxidants, is involved in normal functions. Under pathological conditions, there is a shift toward the oxidants, leading to oxidative stress, which is cytotoxic, causing oxidation of cellular components that result in cell death and organ damage. Thalassemia is a hereditary hemolytic anemia caused by mutations in globin genes that cause reduced or complete absence of specific globin chains (commonly, α or β). Although oxidative stress is not the primary etiology of thalassemia, it mediates several of its pathologies. The main causes of oxidative stress in thalassemia are the degradation of the unstable hemoglobin and iron overload-both stimulate the production of excess free radicals. The symptoms aggravated by oxidative stress include increased hemolysis, ineffective erythropoiesis and functional failure of vital organs such as the heart and liver. The oxidative status of each patient is affected by multiple internal and external factors, including genetic makeup, health conditions, nutrition, physical activity, age, and the environment (e.g., air pollution, radiation). In addition, oxidative stress is influenced by the clinical manifestations of the disease (unpaired globin chains, iron overload, anemia, etc.). Application of personalized (theranostics) medicine principles, including diagnostic tests for selecting targeted therapy, is therefore important for optimal treatment of the oxidative stress of these patients. We summarize the role of oxidative stress and the current and potential antioxidative therapeutics in β-thalassemia and describe some methodologies, mostly cellular, that might be helpful for application of a theranostics approach to therapy.

Paraoxonases (PON) 1, 2, and 3 Polymorphisms and PON-1 Activities in Patients with Sickle Cell Disease

(1) Background: Oxidative stress, chronic inflammation, vasoocclusion, and free iron are all features present in sickle cell disease. Paraoxonases (PON) are a family (PON-1, PON-2, PON-3) of antioxidant enzymes with anti-inflammatory action. Here, for the first time, we described PON-1 activities and PON-1, PON-2, PON-3 polymorphisms in patients with sickle cell disease, homozygous for HbSS, compared with healthy controls. (2) Methods: The groups were matched for age and gender. PON-1 activities (arylesterase and paraoxonase) were determined by enzymatic hydrolysis of phenylcetate and paraoxon, respectively. Polymorphisms were determined by Restriction Fragment Length Polymorphism- Polymerase Chain Reaction (RFLP-PCR). (3) Results: Plasma cholesterol and fractions, ApoA1 and ApoB levels were all decreased in sickle cell disease patients, while anti-oxidized low-density lipoprotein (LDL) antibodies and C-reactive protein were increased. Serum arylesterase activity was lower in sickle cell disease patients when compared with healthy controls. In patients, paraoxonase activity was higher in those with PON-1 RR Q192R polymorphism. In these patients, the increase of serum iron and ferritin levels and transferrin saturation were less pronounced than those observed in patients with QQ or QR polymorphism. No differences were observed with PON-1 L55M, and PON-2 and PON-3 polymorphisms. Multivariate regression analysis showed that transferrin and ferritin concentrations correlated with arylesterase and paraoxonase activities. (4) Conclusions: Both transferrin and ferritin were the main predictors of decreased arylesterase and paraoxonase activities in patients with sickle cell disease. LDL oxidation increased, and RR PON-1 Q192R polymorphism is likely to be a protective factor against oxidative damage in these patients.

Micronuclei and Their Association with Infertility, Pregnancy Complications, Developmental Defects, Anaemias, Inflammation, Diabetes, Chronic Kidney Disease, Obesity, Cardiovascular Disease, Neurodegenerative Diseases and Cancer

Micronuclei (MN) are a strong cytogenetic indicator of a catastrophic change in the genetic structure and stability of a cell because they originate from either chromosome breaks or whole chromosomes that have been lost from the main nucleus during cell division. The resulting genetic abnormalities can to lead to cellular malfunction, altered gene expression and impaired regenerative capacity. Furthermore, MN are increased as a consequence of genetic defects in DNA repair, deficiency in micronutrients required for DNA replication and repair and exposure to genotoxic chemicals and ultraviolet or ionising radiation. For all of these reasons, the measurement of MN has become one of the best-established methods to measure DNA damage in humans at the cytogenetic level. This chapter is a narrative review of the current evidence for the association of increased MN frequency with developmental and degenerative diseases. In addition, important knowledge gaps are identified, and recommendations for future studies required to consolidate the evidence are provided. The great majority of published studies show a significant association of increased MN in lymphocytes and/or buccal cells with infertility, pregnancy complications, developmental defects, anaemias, inflammation, diabetes, cardiovascular disease, kidney disease, neurodegenerative diseases and cancer. However, the strongest evidence is from prospective studies showing that MN frequency in lymphocytes predicts cancer risk and cardiovascular disease mortality.

Acacia Senegal (Gum Arabic) Supplementation Modulate Lipid Profile and Ameliorated Dyslipidemia among Sickle Cell Anemia Patients

Background

Sickle cell disease (SCD) is an inherited haemolytic anemia with a variable course and severity. Knowledge of prognostic biomarkers may help in the establishment of therapeutic intervention, management, and follow-up of patients. There have been scattered reports of low high-density lipoprotein cholesterol (HDL-C) and increased triglyceride (TG) in SCD patients. In addition, TG levels have been suggested to be elevated in patients with increased endothelial activation. An increased TG level has been associated with haemolysis, vascular dysfunction, and increased prevalence of pulmonary hypertension. Gum Arabic (GA) is an edible, dried, gummy exudate from the acacia Senegal tree. Several studies on GA ingestion have shown reduced plasma cholesterol and low-density lipoprotein (LDL) concentrations in both animals and humans. We investigated GA's therapeutic potential to modulate serum lipids in patients with sickle cell anemia.

Methods

This study recruited and documented secondary outcomes in 47 patients (aged 5–42 years) carrying hemoglobin SS. The patients received 30 g/day of GA for 12 weeks. Total cholesterol, TG, LDL, and HDL were measured before and after GA intake. Cobas C311 (Roche, Germany) automated chemistry analyser was used for direct determination of the values of the lipid profile.

Results

GA significantly decreased total cholesterol (TC), TG, and LDL (p = 0.006, 0.04, and 0.02, resp.). GA showed no effect on HDL level. Baseline serum TG and LDL correlated significantly with the hydrogen peroxide (H₂O₂) level, which is known as an oxidative stress marker (p = 0.003 and 0.04, resp.). None of the lipid profile elements correlated with age.

Conclusion

Our results revealed that dyslipidemia in sickle cell patients is associated with oxidative stress but not associated with age. The findings showed that GA significantly decreased TC, LDL, and TG levels, revealing a novel effect of GA, which is considered a natural dietary fibre that can modulate lipid profile in patients with sickle cell anemia.

Trial Registration

This retrospective trial is registered with ClinicalTrials.gov Identifier: NCT02467257 on 3 June, 2015.

Metabolomic Investigation of β-Thalassemia in Chorionic Villi Samples

BACKGROUND

Beta-thalassemias are blood disorders characterized by poorly understood clinical phenotypes ranging from asymptomatic to severe anemia. Metabolic composition of the human placenta could be affected by the presence of pathological states such as β-thalassemia. The aim of our study was to describe metabolic changes in chorionic villi samples of fetuses affected by β-thalassemia compared to a control group by applying a metabolomics approach.

METHODS

Chorionic villi samples were differentiated according to the genetic diagnosis of β-thalassemia: control (Group 1, n = 27); heterozygous (Group 2, n = 7); homozygous (Group 3, n = 7). Gas chromatography-mass spectrometry was used to detect the metabolic composition of the samples. Subsequently, multivariate and univariate statistical analysis was performed. The discriminant metabolites were used to identify the altered pathways.

RESULTS

Supervised multivariate models were devised to compare the groups. The model resulting from the comparison between Group 1 and Group 3 was the most significant. Discriminant metabolites were identified, and the most altered pathways were as follows: pentose phosphate pathway (PPP), arachidonic acid metabolism, glycolysis, and gluconeogenesis, suggesting the presence of an energetic shift toward the PPP and the presence of oxidative stress in β-thalassemia chorionic villi samples.

CONCLUSIONS

The metabolomics approach identified a specific metabolic fingerprint in chorionic villi of fetuses affected by β-thalassemia.

Serum Iron Levels and Copper-to-Zinc Ratio in Sickle Cell Disease

Background and Objectives: Altered copper and zinc homeostasis may influence the antioxidant defense system and consequently lead to oxidative stress and associated complications in sickle cell disease (SCD) patients. Iron levels have been reported to increase in sickle cell patients due to frequent blood transfusion, chronic intravenous haemolysis and increased absorption of iron from the gastrointestinal tract. These elevated levels of iron may also lead to extensive oxidative damage. The current study evaluated serum levels of iron, copper and zinc in SCD patients and "healthy" controls. Materials and Methods: The study was a cross-sectional one, comprising 90 SCD patients with Haemoglobin SS and Haemoglobin SC genotypes and 50 HbAA "healthy" controls. Serum levels of iron, copper and zinc were measured using a Flame Atomic Absorption Spectrometer (Variant 240FS manufactured by VARIAN Australia Pty Ltd, VIC, Australia). Copper and zinc ratios were calculated and analyzed. Results: Serum levels of iron and copper were significantly elevated in the SCD patients, compared to their "healthy" counterparts (p < 0.001). These levels were further increased in patients with haemoglobin SS in vaso-occlusive crises (HbSS VOCs). Serum zinc levels were, however, significantly lower in the SCD patients, particularly during vaso-occlusion. The copper-to-zinc ratio was also found to be significantly higher in the SCD patients. Conclusion: Elevated copper-to-zinc ratio may be a biomarker of sickle cell oxidative stress and associated complications. The ratio may also be informative for the management of sickle cell oxidative burden. The significantly lower levels of zinc in the SCD patients may warrant zinc supplementation.

Redox Signaling in Sickle Cell Disease

Sickle cell disease (SCD) is characterized by chronic hemolysis and repeated episodes of vascular occlusion leading to progressive organ injury. SCD is characterized by unbalanced, simultaneous pro-oxidant and anti-oxidant processes at the molecular, cellular and tissue levels, with the majority of reactions tipped in favor of pro-oxidant pathways. In this brief review we discuss new findings regarding how oxidized hemin, hemolysis, mitochondrial dysfunction and the innate immune system generate oxidative stress while hemopexin, haptoglobin, heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2) may provide protection in human and murine SCD. We will also describe recent clinical trials showing beneficial effects of antioxidant therapy in SCD.

Platelet proteome reveals specific proteins associated with platelet activation and the hypercoagulable state in β-thalassmia/HbE patients

A hypercoagulable state leading to a high risk of a thrombotic event is one of the most common complications observed in β-thalassemia/HbE disease, particularly in patients who have undergone a splenectomy. However, the hypercoagulable state, as well as the molecular mechanism of this aspect of the pathogenesis of β-thalassemia/HbE, remains poorly understood. To address this issue, fifteen non-splenectomized β-thalassemia/HbE patients, 8 splenectomized β-thalassemia/HbE patients and 20 healthy volunteers were recruited to this study. Platelet activation and hypercoagulable parameters including levels of CD62P and prothrombin fragment 1 + 2 were analyzed by flow cytometry and ELISA, respectively. A proteomic analysis was conducted to compare the platelet proteome between patients and normal subjects, and the results were validated by western blot analysis. The β-thalassemia/HbE patients showed significantly higher levels of CD62P and prothrombin fragment 1 + 2 than normal subjects. The levels of platelet activation and hypercoagulation found in patients were strongly associated with splenectomy status. The platelet proteome analysis revealed 19 differential spots which were identified to be 19 platelet proteins, which included 10 cytoskeleton proteins, thrombin generation related proteins, and antioxidant enzymes. Our findings highlight markers of coagulation activation and molecular pathways known to be associated with the pathogenesis of platelet activation, the hypercoagulable state, and consequently with the thrombosis observed in β-thalassemia/HbE patients.

Differentially expressed plasma proteins of β-thalassemia/hemoglobin E patients in response to curcuminoids/vitamin E antioxidant cocktails

OBJECTIVE

Iron overload and oxidative stress are the major causes of serious complications and mortality in thalassemic patients. Our previous work supports the synergistic effects of antioxidant cocktails (curcuminoids or vitamin E, N-acetylcysteine, and deferiprone) in treatment of β-thalassemia/Hb E patients. This further 2-DE-based proteomic study aimed to identify the plasma proteins that expressed differentially in response to antioxidant cocktails.

METHODS

Frozen plasma samples of ten normal subjects and ten β-thalassemia/Hb E patients at three-time points (baseline, month 6, and month 12) were reduced the dynamic range of proteome using ProteoMiner kit and separated proteins by two-dimensional gel electrophoresis. Differentially expressed proteins were identified using tandem mass spectrometry. Several plasma proteins were validated by ELISA and Western blot analysis.

RESULTS

Thirteen and 11 proteins were identified with altered expression levels in the curcuminoids- and vitamin E cocktail groups, respectively. The associations between vitronectin (VTN) expression and total bilirubin levels, as well as between serum paraoxonase/arylesterase 1 (PON1) expression and blood reactive oxygen species were observed. Validation results were consistent with proteomics results.

DISCUSSION AND CONCLUSIONS

These plasma proteins may provide better understanding of the mechanisms underlying the therapeutic effects of antioxidant cocktails in thalassemic patients.

Oxidative Profile of Patients with Sickle Cell Disease

Oxidative stress plays a very significant role in the pathophysiology of sickle cell disease (SCD) and associated complications. Oxidative stress, which is often experienced by SCD patients as a result of continuous production of reactive oxygen species (ROS), may lead to endothelial dysfunction and acute inflammation. Antioxidant enzymes, such as superoxide dismutase (SOD) and catalase (CAT), often play a protective role. The current study aimed at determining the oxidative profile of persons with SCD at a tertiary hospital in Ghana. This was a case-control study involving 90 patients with SCD (34 HbSS patients at steady state, 30 HbSC at steady state, 15 HbSS with vaso-occlusive crisis, 11 HbSC with vaso-occlusive crisis), and 50 HbAA control group. Whole blood samples were collected from the study participants and analyzed for full blood counts. The blood samples were assayed for SOD and CAT as a measure of antioxidant defense, while lipid peroxidation was quantified as malondialdehyde (MDA). The results showed that the levels of SOD and CAT were significantly lower in SCD patients as compared to the control group. Patients with HbSS vaso-occlusive crisis had the lowest levels of SOD and CAT. The difference in SOD levels between HbSS at steady state and HbSC with vaso-occlusive crisis was, however, not significant (p = 0.228). The MDA level was significantly higher in SCD patients compared to the control group. This study concludes that the levels of various antioxidant enzymes (erythrocyte SOD and erythrocyte CAT) and oxidative marker (MDA) and are altered in SCD patients.

Mechanisms of NRF2 activation to mediate fetal hemoglobin induction and protection against oxidative stress in sickle cell disease

IMPACT STATEMENT

Sickle cell disease (SCD) is a group of inherited blood disorders caused by mutations in the human β-globin gene, leading to the synthesis of abnormal hemoglobin S, chronic hemolysis, and oxidative stress. Inhibition of hemoglobin S polymerization by fetal hemoglobin holds the greatest promise for treating SCD. The transcription factor NRF2, is the master regulator of the cellular oxidative stress response and activator of fetal hemoglobin expression. In animal models, various small chemical molecules activate NRF2 and ameliorate the pathophysiology of SCD. This review discusses the mechanisms of NRF2 regulation and therapeutic strategies of NRF2 activation to design the treatment options for individuals with SCD.

Global analysis of erythroid cells redox status reveals the involvement of Prdx1 and Prdx2 in the severity of beta thalassemia

β-thalassemia is a worldwide distributed monogenic red cell disorder, characterized by an absent or reduced beta globin chain synthesis. The unbalance of alpha-gamma chain and the presence of pathological free iron promote severe oxidative damage, playing crucial a role in erythrocyte hemolysis, exacerbating ineffective erythropoiesis and decreasing the lifespan of red blood cells (RBC). Catalase, glutathione peroxidase and peroxiredoxins act together to protect RBCs from hydrogen peroxide insult. Among them, peroxiredoxins stand out for their overall abundance and reactivity. In RBCs, Prdx2 is the third most abundant protein, although Prdxs 1 and 6 isoforms are also found in lower amounts. Despite the importance of these enzymes, Prdx1 and Prdx2 may have their peroxidase activity inactivated by hyperoxidation at high hydroperoxide concentrations, which also promotes the molecular chaperone activity of these proteins. Some studies have demonstrated the importance of Prdx1 and Prdx2 for the development and maintenance of erythrocytes in hemolytic anemia. Now, we performed a global analysis comparatively evaluating the expression profile of several antioxidant enzymes and their physiological reducing agents in patients with beta thalassemia intermedia (BTI) and healthy individuals. Furthermore, increased levels of ROS were observed not only in RBC, but also in neutrophils and mononuclear cells of BTI patients. The level of transcripts and the protein content of Prx1 were increased in reticulocyte and RBCs of BTI patients and the protein content was also found to be higher when compared to beta thalassemia major (BTM), suggesting that this peroxidase could cooperate with Prx2 in the removal of H₂O₂. Furthermore, Prdx2 production is highly increased in RBCs of BTM patients that present high amounts of hyperoxidized species. A significant increase in the content of Trx1, Srx1 and Sod1 in RBCs of BTI patients suggested protective roles for these enzymes in BTI patients. Finally, the upregulation of Nrf2 and Keap1 transcription factors found in BTI patients may be involved in the regulation of the antioxidant enzymes analyzed in this work.

Membrane protein carbonylation of Plasmodium falciparum infected erythrocytes under conditions of sickle cell trait and G6PD deficiency

Deficiency of glucose-6-phosphate dehydrogenase (G6PD) and sickle cell trait (SCT) are described as the polymorphic disorders prevalent in erythrocytes. Both are considered the result of the selective pressure exerted by Plasmodium parasites over human genome, due to a certain degree of resistance to the clinical symptoms of severe malaria. There exist in both a prooxidant environment that favors the oxidative damage on membrane proteins, which probably is part of molecular protector mechanisms. Nevertheless, mechanisms are not completely understood at molecular level for each polymorphism yet, and even less if are commons for several of them. Here, synchronous cultures at high parasitemia levels of P. falciparum 3D7 were used to quantify oxidative damage in membrane proteins of erythrocytes with G6PD deficient and SCT. Carbonyl index by dot blot assay was used to calculate the variation of oxidative damage during the asexual phases. Besides, protein carbonylation profiles were obtained by Western blot and complemented with mass spectrometry using MALDI-TOF-TOF analysis. Erythrocytes with G6PD deficient and SCT showed higher carbonyl index values than control and similar profiles of carbonylated proteins; moreover, cytoskeletal and stress response proteins were identified as the main targets of oxidative damage. Therefore, both polymorphisms promote carbonylation on the same membrane proteins. Finally, these results allowed to reinforce the hypothesis of oxidative damage in erythrocyte membrane proteins as molecular mechanism of human adaptation to malaria infection.

Hemoglobin oxidation-dependent reactions promote interactions with band 3 and oxidative changes in sickle cell-derived microparticles

The contribution of intracellular hemoglobin (Hb) oxidation to RBC-derived microparticle (MP) formation is poorly defined in sickle cell disease (SCD). Here we report that sickle Hb (HbS) oxidation, coupled with changes in cytosolic antioxidative proteins, is associated with membrane alterations and MP formation in homozygous Townes-sickle cell (Townes-SS) mice. Photometric and proteomic analyses confirmed the presence of high levels of Hb oxidation intermediates (ferric/ferryl) and consequent β-globin posttranslational modifications, including the irreversible oxidation of βCys93 and the ubiquitination of βLys96 and βLys145. This is the first report to our knowledge to link the UPS (via ubiquitinated Hb and other proteins) to oxidative stress. Ferryl Hb also induced complex formation with band 3 and RBC membrane proteins. Incubation of Townes-SS MPs with human endothelial cells caused greater loss of monolayer integrity, apoptotic activation, heme oxygenase-1 induction, and concomitant bioenergetic imbalance compared with control Townes-AA MPs. MPs obtained from Townes-SS mice treated with hydroxyurea produced fewer posttranslational Hb modifications. In vitro, hydroxyurea reduced the levels of ferryl Hb and shielded its target residue, βCys93, by a process of S-nitrosylation. These mechanistic analyses suggest potential antioxidative therapeutic modalities that may interrupt MP heme-mediated pathophysiology in SCD patients.

Low IL-2 Expressing T Cells in Thalassemia Major Patients: Is It Immune Aging

Several studies have demonstrated T cell alteration and some features of immunosenescence in thalassemia major. Repeated alloimmunization converts naïve T-cells to memory cells and iron overload causes oxidative stress accelerating immune aging. To determine whether the alteration of T-cell cytokine is matched with early immune aging, the quantity of cytokine expressing T cells and their correlation to some immune aging markers were investigated. The proportion of IL2- and IFNγ expressing CD4+ and CD8+ T-cells was measured in 27 hepatitis B, C and HIV negative B-thalassemia patients and a control group aged 10-30 years, following stimulation for 6 h with streptococcus enterotoxin B and intracellular cytokine staining. This proportion then were analyzed versus the percentage of the T-cells expressing each phenotyping marker, CD27, CD28, CD57 and CCR7. CD4+ and CD8+ positive T cells expressing IL-2 were significantly lower in β-thalassemia major compared to matched controls, but not T cells expressing IFNγ. No significant difference was observed between splenectomized and non-splenectomized patients in cytokine expressing T cells. A negative correlation was noted between the percentage of T cells expressing IFNγ and T-cells expressing CD-27, but not other markers. Lower T cells expressing IL-2 may reveal the decline of naïve and central memory T cells and is likely to be a feature of early immune aging. Decreased antigenic stimulation and iron overload may help to prevent this phenomenon.

Hydroxyurea therapy modulates sickle cell anemia red blood cell physiology: Impact on RBC deformability, oxidative stress, nitrite levels and nitric oxide synthase signalling pathway

Hydroxyurea (HU) has been suggested to act as a nitric oxide (NO) donor in sickle cell anemia (SCA). However, little is known about the HU NO-related effects on red blood cell (RBC) physiology and NO signalling pathway. Thirty-four patients with SCA (22 under HU treatment (HU+) and 12 without (HU-)) and 17 healthy subjects (AA) were included. RBC nitrite content, deformability and reactive oxygen species (ROS) levels were measured. RBC NO-synthase (RBC-NOS) signalling pathway was assessed by the measurement of RBC-NOS serine¹¹⁷⁷ and RBC-AKT serine⁴⁷³ phosphorylation. We also investigated the in vitro effects of Sodium Nitroprusside (SNP), a NO donor, on the same parameters in SCA RBC. RBC nitrite content was higher in HU+ than in HU- and AA. RBC deformability was decreased in SCA patients compared to AA but the decrease was more pronounced in HU-. RBC ROS level was increased in SCA compared to AA but the level was higher in HU- than in HU+. RBC-NOS serine¹¹⁷⁷ and RBC-AKT serine⁴⁷³ phosphorylation were decreased in HU+ compared to HU- and AA. SCA RBC treated with SNP showed increased deformability, reduced ROS content and a decrease in AKT and RBC-NOS phosphorylation. Our study suggests that HU, through its effects on foetal hemoglobin and possibly on NO delivery, would modulate RBC NO signalling pathway, RBC rheology and oxidative stress.

A microfluidic approach to study the effect of mechanical stress on erythrocytes in sickle cell disease

The human red blood cell is a biconcave disc of 6-8 × 2 μm that is highly elastic. This capacity to deform enables it to stretch while circulating through narrow capillaries to ensure its main function of gas exchange. Red cell shape and deformability are altered in membrane disorders because of defects in skeletal or membrane proteins affecting protein-protein interactions. Red cell properties are also altered in other pathologies such as sickle cell disease. Sickle cell disease is a genetic hereditary disorder caused by a single point mutation in the β-globin gene generating sickle haemoglobin (HbS). Hypoxia drives HbS polymerisation that is responsible for red cell sickling and reduced deformability. The main clinical features of sickle cell disease are vaso-occlusive crises and haemolytic anaemia. Foetal haemoglobin (HbF) inhibits HbS polymerisation and positively impacts red cell survival in the circulation but the mechanism through which it exerts this action is not fully characterized. In this study, we designed a microfluidic biochip mimicking the dimensions of human capillaries to measure the impact of repeated mechanical stress on the survival of red cells at the single cell scale under controlled pressure. We show that mechanical stress is a critical parameter underlying intravascular haemolysis in sickle cell disease and that high intracellular levels of HbF protect against lysis. The biochip is a promising tool to address red cell deformability in pathological situations and to screen for molecules positively impacting this parameter in order to improve red cell survival in the circulation.

A Novel Technique of Spectral Discrimination of Variants of Sickle Cell Anemia

Sickle cell anemia (SCA) is an inherited blood disorder with worldwide incidence of 15%; out of this, it is found in up to 20% in countries like Kingdom of Saudi Arabia and Bahrain. The standard conventional method of detection is complete blood count (CBC) followed by hemoglobin electrophoresis or high-performance liquid chromatography (HPLC) or both. In this context, spectral detection of variants of sickle cell anemia (SCA) is an innovative technique, which when made accurate and reliable could be an effective alternative, since the instrumentation is compact (5 kg) and hence portable. This makes mass screening even in remote villages possible. In this paper, we give the essential aspects of fluorescent spectral features of sickle cell trait (SCT), sickle cell disease (SCD), beta (β) thalassemia trait (BTT) + SCD, and beta (β) thalassemia disease (BTD) + SCD. All the above four major variants could be discriminated among themselves and also from the normal control blood sample. All these analyses could be carried out with 5 ml of blood, in a time period of 10 minutes. The results of this paper give strong support for an alternative method, a spectral technique, for molecular-level diagnosis of sickle cell anemia and other closely related blood disorders.

Oxidative stress and phosphatidylserine exposure in red cells from patients with sickle cell anaemia

Phosphatidylserine (PS) exposure increases as red cells age, and is an important signal for the removal of senescent cells from the circulation. PS exposure is elevated in red cells from sickle cell anaemia (SCA) patients and is thought to enhance haemolysis and vaso-occlusion. Although precise conditions leading to its externalisation are unclear, high intracellular Ca2+ has been implicated. Red cells from SCA patients are also exposed to an increased oxidative challenge, and we postulated that this stimulates PS exposure, through increased Ca2+ levels. We tested four different ways of generating oxidative stress: hypoxanthine and xanthine oxidase, phenazine methosulphate, nitrite and tert-butyl hydroperoxide, together with thiol modification with N-ethylmaleimide (NEM), dithiothreitol and hypochlorous acid (HOCl), in red cells permeabilised to Ca2+ using bromo-A23187. Unexpectedly, our findings showed that the four oxidants significantly reduced Ca2+ -induced PS exposure (by 40-60%) with no appreciable effect on Ca2+ affinity. By contrast, NEM markedly increased PS exposure (by about 400%) and slightly but significantly increased the affinity for Ca2+ . Dithiothreitol modestly reduced PS exposure (by 25%) and HOCl had no effect. These findings emphasise the importance of thiol modification for PS exposure in sickle cells but suggest that increased oxidant stress alone is not important.

Potential role of LSD1 inhibitors in the treatment of sickle cell disease: a review of preclinical animal model data

Sickle cell disease (SCD) is caused by a mutation of the β-globin gene (Ingram VM. Nature 180: 326-328, 1957), which triggers the polymerization of deoxygenated sickle hemoglobin (HbS). Approximately 100,000 SCD patients in the United States and millions worldwide (Piel FB, et al. PLoS Med 10: e1001484, 2013) suffer from chronic hemolytic anemia, painful crises, multisystem organ damage, and reduced life expectancy (Rees DC, et al. Lancet 376: 2018-2031, 2010; Serjeant GR. Cold Spring Harb Perspect Med 3: a011783, 2013). Hematopoietic stem cell transplantation can be curative, but the majority of patients do not have a suitable donor (Talano JA, Cairo MS. Eur J Haematol 94: 391-399, 2015). Advanced gene-editing technologies also offer the possibility of a cure (Goodman MA, Malik P. Ther Adv Hematol 7: 302-315, 2016; Lettre G, Bauer DE. Lancet 387: 2554-2564, 2016), but the likelihood that these strategies can be mobilized to treat the large numbers of patients residing in developing countries is remote. A pharmacological treatment to increase fetal hemoglobin (HbF) as a therapy for SCD has been a long-sought goal, because increased levels of HbF (α₂γ₂) inhibit the polymerization of HbS (Poillin WN, et al. Proc Natl Acad Sci USA 90: 5039-5043, 1993; Sunshine HR, et al. J Mol Biol 133: 435-467, 1979) and are associated with reduced symptoms and increased lifespan of SCD patients (Platt OS, et al. N Engl J Med 330: 1639-1644, 1994; Platt OS, et al. N Engl J Med 325: 11-16, 1991). Only two drugs, hydroxyurea and l-glutamine, are approved by the US Food and Drug Administration for treatment of SCD. Hydroxyurea is ineffective at HbF induction in ~50% of patients (Charache S, et al. N Engl J Med 332: 1317-1322, 1995). While polymerization of HbS has been traditionally considered the driving force in the hemolysis of SCD, the excessive reactive oxygen species generated from red blood cells, with further amplification by intravascular hemolysis, also are a major contributor to SCD pathology. This review highlights a new class of drugs, lysine-specific demethylase (LSD1) inhibitors, that induce HbF and reduce reactive oxygen species.

Oxidative stress, antioxidant capacity, biomolecule damage, and inflammation symptoms of sickle cell disease in children

BACKGROUND

The phenotypic expression of sickle cell disease (SCD) is a complex pathophysiologic condition. However, sickle erythrocytes might be the cause for multiple sources of pro-oxidant processes with consequent linked to chronic and systemic oxidative stress. Herein, we explored the SCD phenomena could be the result in formation of oxidative stress as well as inflammation in children.

MATERIAL AND METHODS

Blood samples of 147 SCD subjects were evaluated. A control group was formed of 156 individuals without SCD. Different oxidative stress markers and inflammatory mediators were measured by using various biochemical techniques. Plasma samples were collected from blood for the measurement of antioxidants and reactive oxygen species (ROS).

RESULTS

The levels of plasma hydroxyl radical (HO•), and nitric oxide (NO) production were higher in SCD children in compared to control groups. The plasma antioxidants capacities such as superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx) and protein thiol levels were significantly reduced in SCD children. The plasma lipid peroxidation, protein carbonylation, DNA damage markers were significantly altered in different age groups of SCD children. Further, our results showed that SCD children have chronic inflammatory disease due to persistent alteration of haemoglobin content, reticulocyte, total bilirubin, platelet, creatinine, leukocytes, and altered expression of inflammatory mediators in compared to control groups.

CONCLUSION

SCD children have high oxidative stress, and conversely, decreased antioxidant activity. Decrease in antioxidant activity might explained the reduction in lipid peroxidation, protein carbonylation and increased inflammation, which in turn intensify the symptoms of SCD in children.

Potential involvement of ubiquitin-proteasome system dysfunction associated with oxidative stress in the pathogenesis of sickle cell disease

The ubiquitin-proteasome system (UPS) is an important intracellular proteolytic pathway responsible for the degradation of proteins and oxidative damage; hence it plays a central role in maintaining homeostasis of red blood cells (RBCs). The present study investigated the levels of polyubiquitination, the function of proteasomes and effect of hydroxycarbamide (HC) therapy in RBCs from sickle cell disease (SCD) patients. Polyubiquitinated proteins were found to be elevated in untreated SCD (UT-SCD) patients compared to those in HC-treated SCD patients (HC-SCD) and controls. Activities of β1 and β2 subunits were a little higher in UT-SCD patients, and much higher proteolytic activities were observed in all three subunits (β1, β2 and β5) of RBCs in HC-SCD patients compared to those of UT-SCD patients and controls, although the protein levels of these subunits remained approximately the same. It is notable that, despite HC therapy, some patients showed persistent complications and accumulation of polyubiquitinated proteins. The enhanced proteasomal activity among HC-treated patients might remove the polyubiquitinated protein and could be one of the important mechanisms of therapeutic action. These findings could be useful to understand the pathophysiology of SCD and its clinical heterogeneity and identify a suitable therapeutic target for the better management of these patients.

Decreased Serum Levels of Sphingomyelins and Ceramides in Sickle Cell Disease Patients

Limited data are available on the serum levels of different sphingomyelin (CerPCho) and ceramide (CER) species in sickle-cell disease (SCD). This study was aimed at identifying the levels of C16-C24 CerPCho and C16-C24 CER in serum obtained from SCD patients and controls. Circulating levels of neutral sphingomyelinase (N-SMase) activity, ceramide-1-phosphate (C1P), and sphingosine-1-phosphate (S1P) were also determined. Blood was collected from 35 hemoglobin (Hb)A volunteers and 45 homozygous HbSS patients. Serum levels of C16-C24 CerPCho and C16-C24 CER were determined by an optimized multiple reaction monitoring (MRM) method using ultrafast liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Serum activity of N-SMase was assayed by standard kit methods, and C1P and S1P levels were determined by enzyme-linked immunosorbent assay. A significant decrease was observed in the serum levels of C18-C24 CerPCho in patients with SCD compared to controls. No significant difference was found in C16 CerPCho levels between the two groups. Very-long-chain C22-C24 CER were significantly decreased in SCD, while long-chain C16-C20 CER levels showed no significant difference between SCD patients and controls. Significant positive correlation was found between the serum total cholesterol levels and C18-C24 CerPCho and C22-C24 CER in SCD patients. Patients with SCD had significantly elevated serum activity of N-SMase as well as increased circulating levels of C1P and S1P compared to controls. The decrease in serum levels of C18-C24 CerPCho in patients with SCD was accompanied by decreased levels of C22-C24 CER. Future studies are needed to understand the role of decreased CerPCho and CER in the pathophysiology of SCD.

The effect of xanthine oxidase and hypoxanthine on the permeability of red cells from patients with sickle cell anemia

Red cells from patients with sickle cell anemia (SCA) are under greater oxidative challenge than those from normal individuals. We postulated that oxidants generated by xanthine oxidase (XO) and hypoxanthine (HO) contribute to the pathogenesis of SCA through altering solute permeability. Sickling, activities of the main red cell dehydration pathways (Psickle , Gardos channel, and KCl cotransporter [KCC]), and cell volume were measured at 100, 30, and 0 mmHg O2 , together with deoxygenation-induced nonelectrolyte hemolysis. Unexpectedly, XO/HO mixtures had mainly inhibitory effects on sickling, Psickle , and Gardos channel activities, while KCC activity and nonelectrolyte hemolysis were increased. Gardos channel activity was significantly elevated in red cells pharmacologically loaded with Ca2+ using the ionophore A23187, consistent with an effect on the transport system per se as well as via Ca2+ entry likely via the Psickle pathway. KCC activity is controlled by several pairs of conjugate protein kinases and phosphatases. Its activity, however, was also stimulated by XO/HO mixtures in red cells pretreated with N-ethylmaleimide (NEM), which is thought to prevent regulation via changes in protein phosphorylation, suggesting that the oxidants formed could also have direct effects on this transporter. In the presence of XO/HO, red cell volume was better maintained in deoxygenated red cells. Overall, the most notable effect of XO/HO mixtures was an increase in red cell fragility. These findings increase our understanding of the effects of oxidative challenge in SCA patients and are relevant to the behavior of red cells in vivo.

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.

European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

Transcranial Doppler Screening in 50 Patients With Sickle Cell Hemoglobinopathies in Iran

BACKGROUND

As previous studies had discordant results with regard to the correlation of transcranial Doppler (TCD) screening and brain MRI, the aim of this study was to find the correlation between TCD values and silent ischemia in sickle cell disease (SCD) patients.

METHOD AND MATERIALS

In this cross-sectional study, 50 patients with proven diagnosis of sickle cell hemoglobinopathies based on their hemoglobin electrophoresis were included. Demographic data, their physical exam, information with regard to crises history, and their laboratory data were recorded. Brain MRI and TCD were requested for all patients.

RESULTS

The mean age of the patients was 10.2±5.8 years. Only 3 patients (6%) showed evidence of ischemia on brain MRI. Normal and ischemic patients were not significantly different with respect to TCD values, sex, splenomegaly, aplastic crisis, and laboratory test results (P-value >0.05). Only platelet count was significantly higher in the ischemic group compared with that in the normal group (P=0.002). The pain crisis was significantly associated with the mean velocity values of RMCA, LMCA, RV, and LV arteries (P-value <0.05).

CONCLUSION

On the basis of our results, there was no significant difference in the mean velocity TCD values between patients with and without evidence of ischemic brain damage in brain MRI. The frequency of silent ischemia was much lower than expected. Further studies with larger sample sizes are needed to elucidate the positive predictive value of abnormal TCD in the prediction of silent ischemia in patients with sickle hemoglobinopathy in certain ethnic groups.

Dietary alterations modulate susceptibility to Plasmodium infection

The relevance of genetic factors in conferring protection to severe malaria has been demonstrated, as in the case of sickle cell trait and G6PD deficiency ¹ . However, it remains unknown whether environmental components, such as dietary or metabolic variations, can contribute to the outcome of infection ² . Here, we show that administration of a high-fat diet to mice for a period as short as 4 days impairs Plasmodium liver infection by over 90%. Plasmodium sporozoites can successfully invade and initiate replication but die inside hepatocytes, thereby are unable to cause severe disease. Transcriptional analyses combined with genetic and chemical approaches reveal that this impairment of infection is mediated by oxidative stress. We show that reactive oxygen species, probably spawned from fatty acid β-oxidation, directly impact Plasmodium survival inside hepatocytes, and parasite load can be rescued by exogenous administration of the antioxidant N-acetylcysteine or the β-oxidation inhibitor etomoxir. Together, these data reveal that acute and transient dietary alterations markedly impact the establishment of a Plasmodium infection and disease outcome.

The G6PD flow-cytometric assay is a reliable tool for diagnosis of G6PD deficiency in women and anaemic subjects

Glucose-6-phosphate dehydrogenase (G6PD) activity is essential for redox equilibrium of red blood cells (RBCs) and, when compromised, the RBCs are more susceptible to haemolysis. 8-aminoquinolines (primaquine and tafenoquine) are used for the radical curative treatment of Plasmodium vivax malaria and can cause haemolysis in G6PD deficient subjects. Haemolytic risk is dependent on treatment dose and patient G6PD status but ultimately it correlates with the number of G6PD deficient RBCs. The G6PD spectrophotometric assay reliably identifies deficient subjects but is less reliable in heterozygous females, especially when other blood conditions are present. In this work we analysed samples with a range of G6PD phenotypes and haematologic conditions from 243 healthy volunteers of Asian or African-American heritage using both the spectrophotomeric assay and the G6PD flow-cytometric assay. Overall 18.5% of subjects (29.3% of Asian females) presented with anaemia, associated with decreased RBCs volume (MCV) and reticulocytosis; the flow-cytometric assay showed good correlation with the spectrophotometric assay (Pearson’s r 0.918–0.957) and was less influenced by haemoglobin concentration, number of RBCs and number of reticulocytes. This resulted in more precise quantification of the number of G6PD deficient RBCs and presumably higher predictive power of drug induced haemolytic risk.

Pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a genetic metabolic disease with autosomal recessive inheritance caused by mutations in the ABCC6 gene. The lack of functional ABCC6 protein leads to ectopic mineralization that is most apparent in the elastic tissues of the skin, eyes and blood vessels. The clinical prevalence of PXE has been estimated at between 1 per 100,000 and 1 per 25,000, with slight female predominance. The first clinical sign of PXE is almost always small yellow papules on the nape and sides of the neck and in flexural areas. The papules coalesce, and the skin becomes loose and wrinkled. The mid-dermal elastic fibers are short, fragmented, clumped and calcified. Dystrophic calcification of Bruch's membrane, revealed by angioid streaks, may trigger choroidal neovascularization and, ultimately, loss of central vision and blindness in late-stage disease. Lesions in small and medium-sized artery walls may result in intermittent claudication and peripheral artery disease. Cardiac complications (myocardial infarction, angina pectoris) are thought to be relatively rare but merit thorough investigation. Ischemic strokes have been reported. PXE is a metabolic disease in which circulating levels of an anti-mineralization factor are low. There is good evidence to suggest that the factor is inorganic pyrophosphate (PPi), and that the circulating low levels of PPi and decreased PPi/Pi ratio result from the lack of ATP release by hepatocytes harboring the mutant ABCC6 protein. However, the substrate(s) bound, transported or modulated by the ABCC6 protein remain unknown. More than 300 sequence variants of the ABCC6 gene have been identified. There is no cure for PXE; the main symptomatic treatments are vascular endothelial growth factor inhibitor therapy (for ophthalmic manifestations), lifestyle, lipid-lowering and dietary measures (for reducing vascular risk factors), and vascular surgery (for severe cardiovascular manifestations). Future treatment options may include gene therapy/editing and pharmacologic chaperone therapy.

HbE/β-Thalassemia and Oxidative Stress: The Key to Pathophysiological Mechanisms and Novel Therapeutics

SIGNIFICANCE

Oxidative stress and generation of free radicals are fundamental in initiating pathophysiological mechanisms leading to an inflammatory cascade resulting in high rates of morbidity and death from many inherited point mutation-derived hemoglobinopathies. Hemoglobin (Hb)E is the most common point mutation worldwide. The βE-globin gene is found in greatest frequency in Southeast Asia, including Thailand, Malaysia, Indonesia, Vietnam, Cambodia, and Laos. With the wave of worldwide migration, it is entering the gene pool of diverse populations with greater consequences than expected.

CRITICAL ISSUES

While HbE by itself presents as a mild anemia and a single gene for β-thalassemia is not serious, it remains unexplained why HbE/β-thalassemia (HbE/β-thal) is a grave disease with high morbidity and mortality. Patients often exhibit defective physical development, severe chronic anemia, and often die of cardiovascular disease and severe infections. Recent Advances: This article presents an overview of HbE/β-thal disease with an emphasis on new findings pointing to pathophysiological mechanisms derived from and initiated by the dysfunctional property of HbE as a reduced nitrite reductase concomitant with excess α-chains exacerbating unstable HbE, leading to a combination of nitric oxide imbalance, oxidative stress, and proinflammatory events.

FUTURE DIRECTIONS

Additionally, we present new therapeutic strategies that are based on the emerging molecular-level understanding of the pathophysiology of this and other hemoglobinopathies. These strategies are designed to short-circuit the inflammatory cascade leading to devastating chronic morbidity and fatal consequences. Antioxid. Redox Signal. 26, 794-813.