A Review of Iron Overload in Beta-Thalassemia Major,and a Discussion on Alternative Potent Iron Chelation Targets

Abstract

For years, arrhythmias have been well documented in the medical arena as a cardiovascular consequence of iron overload (IO). They are thought to be linked to the accumulation of iron in the myocardium. Iron is the earth's fourth most abundant element and the second most plentiful metal (after aluminium). When it comes to biology, iron fills two roles: it's necessary and it's poisonous. It is necessary as a trace iron element since it is found in hemoproteins such as haemo-globin, but it is poisonous in excess amounts of the ability to produce free radicals, which can harm the biological system. The high prevalence of cardiomyopathy in patients with hemosiderosis, particularly in cases of transfusional iron overload, strongly suggests that iron deposition in the heart plays a key role in the development of heart failure. Thalassemia major, which necessitates blood transfusion as a treatment, absorbs a large amount of iron in the patient's duodenum. Moreover, Iron Overload causes a threat to vital organs such as the liver and, initiates events of the pathologic progression involving apoptosis, fibrosis, and ultimately cardiac dysfunction. Furthermore, we discuss the iron overload issue as it relates to beta-thalassemia major patient blood transfusion treatment, as well as key individuals accountable for iron excess that ultimately leads to cardiomyopathy.

Keywords

Thalassemia major Iron overload Chelation Methods

Introduction

Thalassemia is a multi-genetic hereditary condition, namely alpha thalassemia, beta-thalassemia, delta beta-thalassemia and some others.¹ Thalassemia is a hereditary disease, which means that at least one parent must be a carrier of the disorder. To be affected by the disorder, a child must receive one abnormal gene from each parent.² It is caused either by a genetic disorder or by the deletion of certain main segments of the gene. In a cluster of the beta-globin gene on chromosome 11,³ and the 16 chromosomes on alpha-globin gene cluster,⁴ molecular defects result in inaccurate production of hemoglobin.⁵ Thalassemia conditions with multiple clinical symptoms, phenotypes and therapeutic options are focused on a continuum of severity. TDT (transfusion-dependent thalassemia) and NTDT (non-transfusion dependent thalassemia) are two types of thalassemia.⁶ In both transfusion-dependent thalassemia and non-transfusion dependent thalassemia, iron overload is associated with high morbidity. Iron overload is caused by an excess accumulation of intestinal iron confirmed by inadequate erythropoiesis.⁷ Excess iron deposition, which begins in the first year of routine blood transfusion, causes harm to many vital organs.

Hemochromatosis, also known as iron overload, is characterized by improper iron accumulation in the functional parts of an organ, which results in organ damage and failure.⁸ Human bodies store iron, mainly in the form of ferritin. Limited content of ferritin is secreted into bloodstreams. The blood ferritin concentration is checked, in the absence of inflammation, this blood ferritin is linked positively corrected, by total body iron stores. Standard concentrations of ferritin differ by sex and age.⁹ Ferritin concentration tends to increase at the age of around one year and even grow in adulthood. Males, however, have a higher level of concentration values than females.¹⁰

As NTDT has indeed been significantly investigated and researched over the past few years, it has been found in patients that do not rely on regular blood transfusion, iron overload differentially affects the liver rather than the myocardium. This was apparent from retrospective studies that demonstrated a lack of cardiovascular siderosis in patients with extreme hepatic iron excess.¹¹ Physiologically there is a lack of a mechanism to remove excess iron load caused by blood transfusion from the human body. 200-250 mg is elemental iron present in each transfused unit of packed red blood cells. Transfusion iron normally amounts to 03 to 0.6 mg/kg per day for TDT patients, with an estimated monthly average transfusion volume of red blood cells filled with 2 to 4 units. This excess iron accounts for the disruption of major vital organs’ functioning and causes irreversible damage.

Cardiomyopathy, often caused by iron overload, is a frequent and preventable form of heart failure.⁸ With atrial and ventricular tachyarrhythmias, iron accumulation in the heart tissue promotes non-homogeneous electrical conduction and repolarization.¹² The entire cardiac conduction system, particularly the atrioventricular node, may be affected by iron deposition. A permanent pacemaker may be required if a complete atrioventricular block is caused by iron deposition.¹³

In almost every nation on the planet, including Northern Europe, where thalassemia was historically absent, migration and marriages between different ethnicities induced thalassemia in humans. Beta-thalassemia has been reported to be around 1.5 per cent of the world's population (80-90 million people) carriers, with about 60,000 serving as symptoms born globally, the overwhelming majority in the developing countries in particular. The internationally estimated average annual frequency of symptomatic people is 1 in 100,000.¹⁴ Beta-thalassemia with irregular Hb or structural Hb form with thalassemia characteristics has been the most common combination within the region of South East Asia with a carrier level of about 50%.² A keyword search of Cardiac arrhythmia was undertaken in the literature databases Pubmed, Gene Reviews, and Scientific Research Journals from 1980 to 2021 for this review paper. With indications of a relationship between arrhythmia and iron overload, primarily in beta-thalassemia major and other blood diseases requiring transfusions, such as hemochromatosis and severe anaemia.

Etiology

Thalassemia is autosomal recessive, which simply means both parents need to be affected with or carrier for the disease to pass it on to the next generation. It is caused by mutations of the Hb genes, resulting in alpha or beta chains being under-produced or not present. More than 200 mutations are known as the causes of thalassemia. Alpha thalassemia and beta-thalassemia are caused by the deletion of alpha-globin and beta-globin genes respectively caused by a point mutation on chromosome 11 in the splice site and promoter regions of the beta-globin gene.¹⁵

Diagnosis

Patients with thalassemia disorder are found to have an incidence count when mild microcytic anemia is observed in their standard blood samples. Thalassemia, iron deficiency, chronic sideroblastic anemia and lead poisoning (also known as plumbism) are responsible for microcytic anemia.¹⁶

Metabolism of thalassemia and iron

Erythropoiesis (from Greek “erythro” meaning “red” and “poiesis’ meaning “to make”) and iron (Fe) metabolism are closely related. The hormone that regulates the absorption of iron is hepcidin, synthesized in the liver.¹⁷ Hepcidin synthesis is regulated by transferrin saturation, the concentration of iron, inflammation and erythropoiesis demand. Several erythroid factors affect hepcidin development, eg growth differentiation factor (GDF-15) and erythroferrone (Erfe). Increased IE (interleukin), anemia, and inflammation lead to a rise in GDF-15 development leading to suppression of hepcidin.¹⁸ This, in turn, results in increased absorption of Fe from the intestine. High intestine absorption of Fe leads to an increase in iron overload, especially in individuals with NTDT (Non-transfusion-dependent Thalassemia) and contributes to the transfusion overload of Fe in individuals with TDT (Transfusion-dependent Thalassemia).

Therapeutic drugs used for the chelation of iron

Iron chelation therapy is used to minimize the accumulation of iron deposition in the patient's vital organs such as the liver and heart. The most common FDA-approved iron chelators are Deferoxamine (DFO), intravenous administration for the treatment of transfusion-induced acute iron overdose and chronic iron excess overload. Deferiprone (DFP), an oral iron chelator with a 3:1 molar ratio of iron-binding, prevent iron buildup but does not adequately prevent iron-induced organ dysfunction, and Deferasirox (DFX/DFRA) is a tridentate oral iron chelator that binds specifically to ferric iron to mobilise stored iron.¹⁹

A severe complication of iron overload in beta-thalassemia is cardiac dysfunction, which results in a 71 per cent mortality rate due to iron accumulation in the myocardium.²⁰ It is critical to reduce LPI (Labile Plasma Iron) and eliminate excess iron to avoid major consequences from iron overload.²¹ Phlebotomy is impossible in individuals with severe beta-thalassemia and hereditary hemochromatosis because they are anaemic. As a result, iron chelation therapy is indeed the best option for treating iron overload.

Efficacy of iron-chelating drugs

Chelating medicines in general have a variety of qualities that can impact iron elimination along with intake, and they can be useful in the treatment of a variety of iron-metabolism diseases, including Beta-Thalassemia, and other Iron-Loaded Non-Transfusion Dependent Thalassemia. In each situation, a risk-benefit evaluation for the chosen therapy is indicated, based on the individual differences as well as the chelating medication's long-term effectiveness, safety, and expense.

Deferasirox (DFX/DFRA) has been reported in iron metabolic balance tests to be effective for increasing faecal, but not urinary, iron excretion, as well as lowering liver iron and serum ferritin values in some patients using the recommended doses of 10–30 mg/kg/day. Medications of 10–40 mg/kg have been observed in iron-loaded thalassemia patients to generate a steady rise in iron excretion, which would have been dose-dependent but not adequate to create a negative iron balance (>15-20 mg iron excretion) in the number of patients at 20 mg/kg or even in most cases at 30 mg/kg/day. In most patients, medication of 40 mg/kg of deferasirox is more effective, with a mean iron excretion rate of 28 mg/day per 50 kg man body weight.²²

DFX/DFRA is now used by millions of transfusional iron-loaded patients. Many current types of research and assessments have been published indicating that DFRA is a relatively effective, well-tolerated, and safe medicine, raising the hopes of many patients for a more effective treatment.²³ Acute renal failure caused mortality, as well as additional major toxic side effects such as Diarrhea, nausea, constipation, and abdominal pain; skin rashes; and a rise in serum creatinine level²⁴ caused by the prolonged use of DFX/DFRA. DFX/DFRA's effectiveness is also challenged, as there is no indication that it can achieve negative iron balance or eliminate excess cardiovascular iron.

The elimination rate of DFO from plasma is faster and is dependent on the route of drug administration. Intravenous DFO has a half-life of 5-10 min while intramuscular DFO has a half-life of roughly 60 min. The elimination of DFO from blood is faster (5-10 min) than that of its iron complex (90 min). It is expected that during the 8-12 h long subcutaneous DFO dose, DFO is eliminated relatively quickly and a threshold level in plasma is reached after about 4 h.²⁵ The most frequent major toxic adverse effects of DFO include ocular, auditory, and bone problems. The side of the DFO injection causes hardness, edoema (excess fluid trapped in the body's tissues), and discomfort in over 80% of thalassaemia patients. To increase DFO compliance and efficacy, different formulations and administration strategies have been used in the past. The oral formulation of DFO did not affect iron excretion.²⁶

In iron-loaded patients, dosages of 75-120 mg/kg/day of Deferiprone (DFO/L1) are usually enough to produce a negative iron balance.²⁷ Gastrointestinal symptoms, granulocytosis, agranulocytosis, and hepatic enzyme increase.²⁸ The combination of DFO and L1 is especially beneficial for patients who are experiencing toxicity from either medicine or who are not fully cooperating with DFO therapy, because compliance with L1 is substantially higher than compliance with DF. In terms of toxicities, the use of combination therapy is especially beneficial for decreasing high doses of subcutaneous or intravenous DFO, which are known to produce auditory and ocular toxicity in a large percentage of patients, as well as L1 dosages that may cause arthropathy.²⁹

Role of Hepcidin in Iron Metabolism

Iron metabolism is a closely controlled biological process with little redundancies, and its disruption frequently results in iron deficiency or iron overload. Anemia, caused by an iron deficiency, is a major public health hazard that affects up to a billion people globally. Iron, on the other hand, has the potential to be toxic.³⁰ It produces reactive oxygen species (ROS) when it combines with oxygen, causing cell damage. Three regulatory mechanisms manage iron metabolism in mammals: one controls cellular iron metabolism through iron regulatory proteins (IRPs), which bind iron-responsive elements (IREs) in regulated mRNAs.³¹ In humans, low hepcidin levels cause iron overload (IO). As a result of low hepcidin levels and ferroportin overexpression, iron overload is caused by increased iron export from enterocytes and macrophages. Iron builds up in vital organs including the heart, liver, and pancreas, causing oxidative stress and conditions like cirrhosis, cancer, diabetes, and cardiomyopathy.³² As shown in “[ Figure 1]”.

Figure 1.

(A) Elevated iron levels beta thalassemia major, a result of continuous blood transfusions received from packed red blood cell (PRCB) which around 200-250 mg of iron. A small amount of iron is secreted from the excretion route and through menstrual bleeding in adolescent girls and adult females. (B) Hepcidin, a major iron regulator which is severely monitored, IL-6 activates hepcidin via the IL-6 receptor (IL-6R) and JAK2-STAT3 signalling pathways. In active BMP-SMAD pathway enables a normal hepcidin expression which inhibits the expression of iron stores and manages the iron metabolism. Transferrin binds iron and transports it through the bloodstream. The majority of iron is needed for erythropoiesis. (C) An active BMP-SMAD is required for full hepcidin activation. In beta thalassemia major, an inactive BMP-SMAD pathway causes decreased production of hepcidin, which is unable to block iron reserves transferred from FPN in macrophages and Entrocytes, resulting in iron overload which leads oxidative stress and cellular damages to major vital organs such as heart, liver and intestine.

Iron Overload in beta-Thalassemia

Standard blood transfusions are required in the most severe form of beta-thalassemia to reduce the risk of anaemia. Iron overload is caused by RBC (red blood cell) count being boosted by monthly blood transfusions, hemolysis, and increased absorption of iron from the duodenum and proximal jejunum.³³ Cardiac stiffness is the major cause of death in thalassemia patients who have received blood transfusions.³⁴ 1-2 mg of iron is excreted from the human body in a day, whereas a transfused red blood cell unit contains about 200 mg of iron.³⁵ In absence of any iron chelation therapy, an individual getting 25 blood units a year requires 5 g of iron each year. Iron toxicity is highly harmful to all cells in the body and can cause severe and permanent organ failure, such as liver disease, diabetes, cardiac failure and testosterone deficiency.³⁴ The iron surcharge in the bloodstream can be measured using, urinary iron excretion, hepatic iron content, serum ferritin and TIBC (Total Iron Binding Capacity) levels.⁷ The iron toxicity threshold values are concentration of, serum ferritin > 2500 ng/mL, urinary iron discharge> 20 mg/day, concentration of liver iron more than 440 mmol/g and transferrin congestion> 75%.³⁶ Estimating the concentration of hepatic iron by MRI (magnetic resonance imaging) is a widely used method in beta-thalassemia major to assess the overburden of iron³⁷ T2* Magnetic Resonance Imaging (T2* MRI) is a non-invasive approach for determining heart and liver iron overload.³⁸ T2* MRI is a highly reproducible and sensitive approach for detecting cardiovascular iron overload. Serum ferritin did not affect the T2* MRI reading (p-value: 0.464).³⁹ Iron over-burden has additionally been seen in patients with NTDT (non-transfusion-subordinate thalassemia).⁴⁰ Beta-thalassemia with histidine to aspartic acid (H63D) experiences mutation in carriers patients, and iron overload at codon 63 of the HFE gene which indicates that the H63D mutation can influence the absorption of iron.⁴¹ Iron overabundance increases the risk of hepatitis, (swollen liver), fibrosis, and or irreversible damage to the liver due to scarring iron excess also leads the chance of abnormal heart rhythms/arrhythmias, or, and cardiac obstruction.²⁴

Signaling pathways that regulate Hamp/Hepcidin expression

Stat3 signaling pathways- Stat3 signaling pathway is a regulator for hepcidin, mostly through inflammation.⁴² This contributes to the development of IL-6 and IL-22 but not to IL-1β and factor-α tumour necrosis (TNF-α).⁴³ The Stat3-binding site and the SiRNA- mediated Stat3 knockdown contain a promoter from Hamp which significantly lower the transcription of hepcidin. Stat3 signaling pathway is important not only under conditions of inflammation but also under expression of baseline hepcidin.⁴³ The activation of IL-6-mediated hepcidin is based on the signaling pathway IL-6-Stat3.IL-6 binds to the IL-6 receptor (IL-6R), then to glycoprotein 130 (gp130), causing Stat3 phosphorylation, which facilitates Stat3 translocation to the nucleus and triggers Hamp transcriptions.⁴⁴

Other signaling pathways that regulate Hamp/Hepcidin expression

In Hamp promoter, estrogen was found as a sex hormone to down-regulate Hamp expression via an estrogen receptor element (ERE).⁴⁵ A report indicated that the membrane component, PGRMC1 (membrane-bound progesterone receptor-1), also contributes to the modulation of hepcidin by Src-family tyrosine kinases (SFKs).⁴⁶ The downstream signaling of SFKs responsible for the regulation of Hamp expression is still unclear,⁴⁶ and needs further study.

Hepcidin is regulated by BMP/SMAD protein pathway

There are approximately 20 mammalian bone morphogenetic proteins (BMPs), among which BMP2, BMP4, BMP5, BMP6, BMP7 and BMP9 can cause Hamp expression.⁴⁷ Studies have shown that the most important among all of the bone morphogenetic proteins (BMPs) is BMP6 which is an important factor in the regulation of hepcidin.⁴⁷ To activate Smad1/5/8 phosphorylation, it attaches to the BMP receptor (BMPR), and then it translocates to the nucleus together with Smad4 and binds to the Hamp promoter to promote Hamp transcription.⁴⁸ BMPR type I expresses only Activin-Like Kinase 2/3mammals.⁴⁹ Unlike many other members of the BMP protein family, the BMP signaling pathway is the essential iron-mediated regulator of hepcidin as BMP6 is sensitive to iron concentrations. BMP6 is developed in non-parenchymal liver cells and stimulated by iron; its expression is relative to the amount of hepatic iron. Furthermore, neutralizing the BMP6 antibody may reduce hepcidin expression and cause serum iron concentrations to increase in mice.

Cardiac Dysfunction and its Relation with Iron Toxicity

Iron is a two-pronged element, its role as an oxygen carrier plays a critical role in catalyzing enzyme reactions, and disruption in iron homeostasis results in excessive iron intake and storage, which is harmful to various tissues and organs. Toxic levels of ferrous iron are primarily exhibited as cardiac dysfunction and failure, as well as liver dysfunction and cirrhosis and diabetes mellitus in the endocrine system. These conditions are generally detected in the late stages of their recurrence when consequences have already been developed. Arrhythmias and increasing systolic dysfunction are commonly caused by iron accumulation in the heart muscle tissue. A dilated cardiomyopathy with poor left ventricular ejection fraction (LVEF) is the most common manifestation, which can be reversed only if recognized and treated in the early stages of diagnosis.⁵⁰ This condition is often asymptomatic. Iron deposition can occur throughout the cardiac conduction system, particularly in the atrioventricular node. Severe atrioventricular block due to iron accumulation.¹³ Non-homogeneous electrical conduction and repolarization induce cardiomyopathy with atrial and ventricular tachyarrhythmia and iron buildup in heart muscle.¹²

Tf-bound iron is not a limiting factor under normal settings, and the absorption of iron into cells is regulated by TfR1 expression.⁵¹ As a result, iron overload occurs only when Tf's binding ability is exhausted and non-transferrin-bound iron (NTBI) or labile plasma iron (LPI), the portion of NTBI that may infiltrate cells and is chelatable, is present.⁵² Although NTBI is linked to tissue siderosis, the exact mechanism by which it enters the cell is unknown, owing to a lack of complete characterization of the iron species involved, which have a variable composition under different pathological conditions and change their association with macromolecules. Several plasma components, including citrate, phosphates and proteins, are said to be linked to NTBI.⁵³ Iron toxicity in cells is caused by its ability to catalyze the reactive oxygen species (ROS),⁵⁴ which induce lipid peroxidation and organelle damage, resulting in cell death and fibrosis, as well as reduced systolic and diastolic function. Cell damages caused by iron are not limited to cases of systemic iron overload. Unfair iron distribution within organs or tissues, as well as among cellular compartments, has been shown to impact cell integrity and longevity. Ischemic heart disease or myocardial infarction is not connected with cardiac hemochromatosis,⁵⁵ thus there is a lack of knowledge regarding the basic mechanism of iron overload-induced arrhythmia.⁵⁶

Iron Excretion

The amount of iron in the human body is calculated through dietary consumption of iron, not through iron excretion. The removal of iron from the human body is handled at a very small rate. The faecal secretion of iron is equivalent to the consumption of iron by diet, and zero in the case of iron by transfusion.⁵⁷ However, several cases such as blood transfusion in beta-thalassemia which suppress in production of hepcidin may lead to an overload of iron. Unintentional exposures can cause the majority of serious medical problems, such as cardiac arrhythmia and liver failure. As a result, iron absorption is continuously monitored to prevent cell damage. The toxification of iron mainly occurs where it is stored i.e, in the liver. Biliary iron excretion estimated a significant amount of excess iron extraction through the bile and remaining to be processed for the reuse of hemoglobin synthesis.⁵⁸ Urinary iron excretion a usual routine excretion of iron in the urine is a large proportion of the overall daily iron depletion.⁵⁹

Therapeutic Targets in Beta-Thalassemia

Mini-hepcidin

Since low hepcidin levels are associated with greater Fe absorption in the intestine; inhibitors of hepcidin in thalassemia patients may boost the iron load. Small peptides such as Mini-hepcidin mimetics are necessary to induce hepcidin actions; hence, serum iron levels decrease and iron overload improves. By using this mini-hepcidin, iron overload and damage to the erythroid cells are significantly reduced.⁶⁰

Apo-transferrin administration

Apo-transferrin administration can decrease labile plasma iron concentrations, leading to a normalization of RBC survival and increased production of Hb. The protein also exists during the early phases of a clinical study.⁶¹ As the Hamp negative regulator, 17b estradiol (E2) therapy reduced Hamp expression in cell lines HuH7 and Hep G2, which could be blocked by ICI 182780, an estrogen receptor antagonist.⁴⁵

JAK2 inhibitors

These agents have substantial antiproliferative and anti-inflammatory activity in patients with b-thalassemia, to regulate splenomegaly and extra-modular hematopoiesis.⁶² Through suppressing the EPO's key signaling pathway on progenitor erythrocytes, similar agents can have therapeutic effects on splenomegaly and secreted blood from the spleen, resulting in fewer transfusion needs. These agents can be used in place of splenectomy, once proven to be safe and to decrease additional medullary hematopoiesis.

Activin receptor Ii ligand traps

These model ligands (Luspatercept/Sotatercept) suppress over activated SMAD signals in erythroid precursors which inhibit the effect of GDF-11 cytokine on differentiation and maturation of the advanced stage erythrocytes. These ligands have been shown to mitigate complications from IE (ineffective erythropoiesis) diseases, minimizing the excess iron and reducing bone disease deformities in animal models.⁶³ Ongoing clinical trials are being carried out which show improvements in 12 weeks of studies on the impact of these drugs on IE and transfusion-dependent beta-thalassemia patients.⁶⁴

Transferrin

The main protein in the transportation of iron is transferrin, which binds to Fe3 + molecules, transported iron is bound to (TfR1) receptor 1 and (TfR2) receptor 2. Transferrin is endocytosed, the lysosomal, acid framework Fe3 + is produced from transferrin and is reduced to Fe2 + and is then entered into the cytosol through divalent metallic transporter 1. Whereas TfR1 with high transferrin saturation is down-regulated.TfR2 is specific in the liver and intestine, because of high liver iron concentration (LIC), TfR2 lacks an iron-responsive feature and the iron charge in the liver continues. In most tissues, including the erythroid, a liver and myocardial precursor, TfR1 is expressed.⁶⁵

TMPRSS6

TMPRSS6 is a membrane binding serine protease in hepatocytes, it is also known as matriptase-2,⁶⁶ which modulates the production of hepcidin negatively.⁶⁷ TMPRSS6 cleaves HJV (hemojuvelin) from plasma membrane favourable in vitro conditions.⁶⁷ This means that TMPPRSS6 down-regulates the critical BMP/SMAD signalling route important for iron-dependent hepcidin transcription regulations.

BCL11A (B cell lymphoma-leukaemia 11a)

A decent approach for gene editing strategies is the BCL11a (TF controlling the transition from HbF to HbA). It is postulated that the production of HbF in thalassemia patients can be triggered by suppressing the BCL11a. Deletions in the BCL11a erythroid enhancer are a promising approach, which is being investigated.⁶⁸ The Long-dimensional interactions across the β-globin gene locus between BCL11A and several regions could mediate β-globin gene silence. Whether this is a direct result of the suppression of BCL11A or an indirect effect due to the activation of γ-globin by another process is uncertain.

Therapies Under Investigation for Iron Overload

Hepcidin deficiency treatment

Hepcidin, the hormone which regulates the accumulation of absorption of iron and its abnormal transportation are a cause of iron overload in nearly every form of hereditary hemochromatosis and non-transfused iron overloading anemia.⁶⁹ Analogues of hepcidin have also been seen reducing the toxicity of the iron-mediated tissue in mouse models.⁶⁹ Agonists of hepcidin known as Mini-hepcidin are based on peptides that are rationally planned, based on the hepcidin field engaging with the ferroportin.⁶⁰ Mini-hepcidin may be helpful in iron excessive conditions used for treatment or chelation treatment.⁷⁰ Analogues of normal hepcidin and mini-hepcidin are studied for preventing the overloading of iron in hemochromatosis and beta-thalassemia. As deficiency in hepcidin causes an overload of iron It would be expected that agents capable of mimicking hepcidin action or potentiating its endogenous production would inhibit iron.⁷¹

Gene therapy management

The treatment by gene therapy of genetic conditions such as sickle cell anemia and beta-thalassemia will prevent blood transfusions and reduce iron overload in the tissues.⁷² In individuals with hereditary hemochromatosis and beta-thalassemia including the DMT-1 activation and gene expression of ferroportin in enterocytes Over-expression of the wild-type HFE gene in enterocytes and overexpression of the iron regulatory peptide hepcidin in the liver are other therapeutic strategies that could be studied.⁷³ The HFE genotype may influence the survival of myelodysplastic syndrome patients and tests need to be carried out if these patients are to be treated with effective iron chelation therapy.⁴¹

Discussion

In the Indian subcontinent, the common genetic disorder is Thalassemia. Hyper-transfusion has improved the expected lifespan of thalassemic patients over the decades, but the excessive number of blood transfusions ensures iron overload is an inevitable complication major in thalassemia patients.⁷⁴ Several studies have concluded that cirrhosis of the liver is associated with increased levels of serum ferritin.⁷⁵ Iron is an essential component in biochemical and biological processes, however, when excess, oxidative stress can lead to tissue damage. Excess iron in the body can cause damage to organs such as the liver, spleen, liver, bone marrow, pancreas, pituitary gland and nervous system.

In the last 20 years, thalassemia major management has developed to the point where the life expectancy of patients is as high as normal inhabitants. Therapies that reduce transfusion demands in TDT and remove insufficient erythropoiesis in NTDT may in this way be promising. Specific disruptions in factors like BCL11A that may potentially lead to γ-globin genes being kept suppressed may result in simpler and safer treatment of β-thalassemia, depending on transfusions or non-transfusions.⁷ The developmental stage-specific BCL11A repressor regulates the expression of hemoglobin. The use of strengthened activin receptors to enhance delay erythropoiesis by functioning as ligand traps for the participants in the transformation of superfamily growth factors is also a promising method, currently being tested in clinical studies.⁶⁵ Therapy with these agents aims to increase hemoglobin levels and reduce the need for transfusion in both NTDT and TDT patients.

Conclusion

In thalassemia major, cardiac illness is still the leading cause of death. Transfusion and iron chelation treatments have greatly improved survival and reduced morbidity in thalassemic patients. In the past patients died by the age of 16, while now 80 per cent live to be at least 40 years of age. This is of a kind improvement, as no other previously fatal genetic flaw has shown such a benefit. Heart complications, on the other hand, continue to be a substantial cause of morbidity and mortality in transfusion-dependent thalassemia (TM) patients. Some tests can detect the possibility of thalassemia in neonates; however, depending on the severity of the thalassemia, blood transfusions may be necessary at a very early stage of life. In the human body, iron is essential for the creation of heme enzymes and other iron-containing enzymes involved in electron transfer and oxidation reductions, as well as the synthesis of oxygen transport proteins such as haemoglobin and myoglobin. The majority of iron is delivered via haemoglobin, which circulates in erythrocytes. However, 15% of iron is found in myoglobin, which is found in muscle tissue and a variety of other tissues. Transferrin binds to iron and transports it throughout the body, where it is stored in ferritin molecules. There is no physiologic mechanism for excreting excess iron from the body once it has been absorbed, other than blood loss, such as during pregnancy, menstruation, or other periods of bleeding. As a result, unabsorbed iron can lead to liver disease, cardiac troubles, diabetes, and problems with human growth. The percentage of iron absorbed from the total amount consumed is normally low, ranging from 5 to 35 per cent based on the circumstances and type of iron consumed.

Hepcidin is a peptide hormone released by the liver that plays an important function in iron homeostasis management. It is a potent inhibitor of systemic iron homeostasis, coordinating iron uptake, usage, and storage. Hepatocytes produce it, and it's a negative regulator of iron absorption into the bloodstream. Hepcidin specifically binds to ferroportin, an iron transporter found in intestine duodenal cells, macrophages, and placental cells. The absence of ferroportin on the cell membrane prevents iron from entering the bloodstream. Low transferrin saturation results from less iron entrance into plasma and less iron is supplied to the erythroblast. Higher cell surface ferroportin and increased iron absorption resulted from decreased hepcidin expression. By this hepcidin and its interacting constituents (ferroportin, transferring) became a potent target for tapping the iron overload problem. These are discussed briefly in the review article.

Clinicians utilize the classic iron chelation approach (use of drugs ie, Deferoxamine, Deferiprone and Deferasirox) to treat iron overload in patients who get regular blood transfusions, even though this method has a significant risk of side effects in later life of patients. There is no insightful topic in agreement on the excretion of excess iron; nevertheless, if the study focuses on excess iron excretion from the body system, individuals with thalassemia who require regular blood transfusions may be cured and lead a longer and healthier life. The use of computational biology and drug design methods is important in the quest for a powerful inhibitor of iron overload, and the results can be confirmed in vivo facility. An alternative to iron chelation that has fewer adverse effects on the human body can be designed. New emerging technologies (Drug Designing and Lead Identification) could help find a better-designed inhibitor in iron overload.

Footnotes

Acknowledgements

Author(s) would like to acknowledge the Department of Bioinformatics, Central University of South Bihar, Gaya Bihar and the Indian Council of Medical Research, New Delhi India for all technical and financial support.

Author Contributions

The authors have contributed equally to the manuscript.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

This work is supported by the Indian Council of Medical Research, New Delhi India under the ICMR Grant (ISRM/12(22)/2019, ID No. 2019-0370) for this manuscript.

ORCID iD

Ajay Kumar Singh

References

Marengo-Rowe

. The thalassemias and related disorders. Baylor Univ Med Cent Proc. 2007;20(1)(Jan):27-31.

Galanello

Origa

. Beta-thalassemia. Orphanet J Rare Dis. 2010;5(Aug):1-15.

Thein

. Molecular basis of β thalassemia and potential therapeutic targets. Blood Cells, Mol Dis. 2018;70(May):54-65.

Farashi

Harteveld

. Molecular basis of α-thalassemia. Blood Cells, Molecules, and Diseases. 2018;70(May):43-53.

Muncie

Campbell

. Alpha and beta thalassemia. Am Fam Physician. 2009(Aug):339–344.

Musallam

Rivella

Vichinsky

Rachmilewitz

. Non-transfusion-dependent thalassemias. Haematologica. 2013;98(6)(Jun):833-844. doi: 10.3324/haematol.2012.066845

Mishra

Tiwari

. Iron overload in Beta thalassaemia major and intermedia patients. Maedica (Buchar). 2013;8(4)(Sep):328-332.

Aronow

. Management of cardiac hemochromatosis. Arch Med Sci. 2018;14(Apr):560-568. doi: 10.5114/aoms.2017.68729.

Domellöf

Dewey

Lönnerdal

Cohen

Hernell

. The diagnostic criteria for iron deficiency in infants should be reevaluated. J Nutr. 2002;132(Dec):3680-3686. doi: 10.1093/jn/132.12.3680.

10.

Gibson

. Principles of Nutritional Assessment. 2nd. Editor Gibson

ed. Oct. Oxford University Press Inc.; 2005.

11.

Taher

Musallam

Wood

Cappellini

. Magnetic resonance evaluation of hepatic and myocardial iron deposition in transfusion-independent thalassemia intermedia compared to regularly transfused thalassemia major patients. Am J Hematol. 2010;85(Apr):288-290. doi: 10.1002/ajh.21626.

12.

V-C

Huang

J W

M-S

, et al. The effect of iron stores on corrected QT dispersion in patients undergoing peritoneal dialysis. Am J Kidney Dis Off J Natl Kidney Found. 2004;44(Oct):720-728.

13.

Aronow

Meister

Kent

. Atrioventricular block in familial hemochromatosis treated by permanent synchronous pacemaker. Arch Intern Med. 1969;123(Apr):433-435.

14.

Vichinsky

. Changing patterns of thalassemia worldwide. Ann N Y Acad Sci. 2005;1054:18-24. doi: 10.1196/annals.1345.003.

15.

Jalil

Yousafzai

Y M

Rashid

, et al. Mutational analysis of Beta thalassaemia by Multiplex Arms-Pcr in Khyber Pakhtunkhwa, Pakistan. J Ayub Med Coll Abbottabad. 2019;31(Jan-Ma):98-103.

16.

Brancaleoni

Di Pierro

Motta

Cappellini

. Laboratory diagnosis of thalassemia. Int J Lab Hematol. 2016;38(May):32-40. doi: 10.1111/ijlh.12527.

17.

Sangkhae

Nemeth

. Regulation of the iron homeostatic hormone Hepcidin. Adv Nutr. 2017;8(Jan):126-136. doi: 10.3945/an.116.013961

18.

Pagani

Nai

Silvestri

Camaschella

. Hepcidin and Anemia: a tight relationship. Front Physiol. 2019;10(Oct):1294. doi.org/10.3389/fphys.2019.01294

19.

Mobarra

Shanaki

Ehteram

, et al. A review on iron chelators in treatment of iron overload syndromes. Int J Hematol Stem Cell Res. 2016;10(Oct):239-247.

20.

Brittenham

Griffith

P M

Nienhuis

A W

, et al. Efficacy of deferoxamine in preventing complications of iron overload in patients with thalassemia major. N Engl J Med. 1994;331(Sep):567-573. doi: 10.1056/NEJM199409013310902.

21.

Xiao

Beibei

Guangsi

, et al. Iron overload increases osteoclastogenesis and aggravates the effects of ovariectomy on bone mass. J Endocrinol. 2015;226(Sep):121-134. doi: 10.1530/JOE-14-0657

22.

Nisbet-Brown

Olivieri

N F

Giardina

P J

, et al. Effectiveness and safety of ICL670 in iron-loaded patients with thalassaemia: a randomised, double-blind, placebo-controlled, dose-escalation trial. Lancet (London, England). 2003;361(May):1597-1602. doi: 10.1016/S0140-6736(03)13309-0

23.

Nick

Acklin

Lattmann

, et al. Development of tridentate iron chelators: from desferrithiocin to ICL670. Curr Med Chem. 2003;10(May):1065-1076. doi: 10.1016/S0140-6736(03)13309-0.

24.

Taher

Porter

Viprakasit

, et al. Deferasirox reduces iron overload significantly in nontransfusion-dependent thalassemia: 1-year results from a prospective, randomized, double-blind, placebo-controlled study. Blood. 2012;120(Aug):970-977. doi: 10.1182/blood-2012-02-412692.

25.

Keberle

. The biochemistry of desferrioxamine and its relation to iron metabolism. Ann N Y Acad Sci. 1964;119(Oct):758-768. doi: 10.1111/j.1749-6632.1965.tb54077.x.

26.

Pippard

Callender

Weatherall

. Intensive iron chelation therapy with desferrioxamine in iron loading anaemias. Clin Sci Mol Med. 1978;54(Jan):99-106. doi: 10.1042/cs0540099.

27.

Kontoghiorghes

Aldouri

M A

Hoffbrand

A V

, et al. Effective chelation of iron in beta thalassaemia with the oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one. Br Med J (Clin Res Ed). 1987;295(Dec):1509-1512. doi: 10.1136/bmj.295.6612.1509

28.

Taher

Saliba

. Iron overload in thalassemia: different organs at different rates. Hematology. 2017;2017(Dec):265-271. doi: 10.1182/asheducation-2017.1.265

29.

Kellenberger

, et al. Radiographic and MRI features of deferiprone-related arthropathy of the knees in patients with β-thalassemia. Am J Roentgenol. 2004;183(OCT):989-994.

30.

Liberal

Pinela

Vívar-Quintana

Ferreira

ICFR

Barros

. Fighting iron-deficiency anemia: innovations in food fortificants and biofortification strategies. Foods. 2020;9(Dec):1-19. doi: 10.3390/foods9121871

31.

Muckenthaler

Galy

Hentze

. Systemic iron homeostasis and the iron-responsive element/iron-regulatory protein (IRE/IRP) regulatory network. Annu Rev Nutr. 2008;28(Aug):197-213. doi: 10.1146/annurev.nutr.28.061807.155521

32.

Chifman

Laubenbacher

Torti

. A systems biology approach to iron metabolism. Adv Exp Med Biol. 2014;844:201-225.

33.

Gulec

Anderson

Collins

. Mechanistic and regulatory aspects of intestinal iron absorption. Am J Physiol. Gastrointest. Liver Physiol. 2014;307(Aug):G397-G409. doi: 10.1152/ajpgi.00348.2013.

34.

Ginzburg

Rivella

. β-thalassemia: a model for elucidating the dynamic regulation of ineffective erythropoiesis and iron metabolism. Blood. 2011;118(Oct):4321-4330. doi: 10.1182/blood-2011-03-283614

35.

Lymboussaki

, et al. The role of the iron responsive element in the control of ferroportin1/IREG1/MTP1 gene expression. J Hepatol. 2003;39(Nov):710-715. doi: 10.1016/s0168-8278(03)00408-2.

36.

Hershko

. Pathogenesis and management of iron toxicity in thalassemia. Ann N Y Acad Sci. 2010;1202(Aug):1-9. doi: 10.1111/j.1749-6632.2010.05544.x.

37.

Henninger

, et al. Evaluation of MR imaging with T1 and T2* mapping for the determination of hepatic iron overload. Eur Radiol. 2012;22(Nov):2478-2486. doi: 10.1007/s00330-012-2506-2

38.

Wood

. Magnetic resonance imaging measurement of iron overload. Curr Opin Hematol. 2007;14(May):183-190. doi: 10.1097/MOH.0b013e3280d2b76b

39.

Alvi

, et al. Burden of cardiac siderosis in a thalassemia-Major endemic population: a preliminary report from Pakistan. J Pediatr Hematol Oncol. 2016;38(Jul):378-383. doi: 10.1097/MPH.0000000000000574

40.

Musallam

Cappellini

Taher

. Iron overload in beta-thalassemia intermedia: an emerging concern. Curr Opin Hematol. 2013;20(May):187-192. doi: 10.1097/MOH.0b013e32835f5a5c.

41.

Lucijanic

, et al. Hemochromatosis gene mutations may affect the survival of patients with myelodysplastic syndrome. Hematology. 2016;21(Apr):170-174. doi: 10.1080/10245332.2015.1101964

42.

Pigeon

, et al. A new mouse liver-specific gene, encoding a protein homologous to human antimicrobial peptide hepcidin, is overexpressed during iron overload. J Biol Chem. 2001;276(Mar):7811-7819. doi: 10.1074/jbc.M008923200

43.

Verga Falzacappa

, et al. STAT3 Mediates hepatic hepcidin expression and its inflammatory stimulation. Blood. 2007;109(Jan):353-358. doi: 10.1182/blood-2006-07-033969

44.

Lee

Herrmann

Buettner

Jove

. Revisiting STAT3 signalling in cancer: new and unexpected biological functions. Nat Rev Cancer. 2014;14(Nov):736-746. doi: 10.1038/nrc3818.

45.

Yang

Jian

Katz

Abramson

Huang

. 17beta-Estradiol Inhibits iron hormone hepcidin through an estrogen responsive element half-site. Endocrinology. 2012;153(Jul):3170-3178. doi: 10.1210/en.2011-2045

46.

, et al. Progesterone receptor membrane component-1 regulates hepcidin biosynthesis. J Clin Invest. 2016;126(Jan):389-401. doi: 10.1172/JCI83831

47.

Andriopoulos

, et al. BMP6 Is a key endogenous regulator of hepcidin expression and iron metabolism. Nat Genet. 2009;41(Apr):482-487. doi: 10.1038/ng.335

48.

Wang

R-H

, et al. A role of SMAD4 in iron metabolism through the positive regulation of hepcidin expression. Cell Metab. 2005;2(Dec):399-409. doi: 10.1016/j.cmet.2005.10.010

49.

Core

Canali

Babitt

. Hemojuvelin and bone morphogenetic protein (BMP) signaling in iron homeostasis. Front Pharmacol. 2014;5(MAY):1-9.

50.

Sudmantait

Celutkien

Glaveckaite

Katkus

. Difficult diagnosis of cardiac haemochromatosis: a case report.. Eur Heart J Case Rep. 2020;4(Jan):1–6. doi: 10.1093/ehjcr/ytaa012

51.

Frazer

Anderson

. The regulation of iron transport. Biofactors. 2014;40(Mar-Apr):206-214. doi: 10.1002/biof.1148.

52.

Cabantchik

. Labile iron in cells and body fluids: physiology, pathology, and pharmacology. Front Pharmacol. 2014;5(MAR):1-11. doi: 10.3389/fphar.2014.00045

53.

Patel

Ramavataram

DVSS

. Non transferrin bound iron: nature, manifestations and analytical approaches for estimation. Indian J Clin Biochem. 2012;27(Oct):322-332. doi: 10.1007/s12291-012-0250-7

54.

Brissot

Ropert

Le Lan

Loréal

. Non-transferrin bound iron: a key role in iron overload and iron toxicity. Biochim Biophys Acta. 2012;1820(Mar):403-410.

55.

Candore

, et al. Association between HFE mutations and acute myocardial infarction: a study in patients from northern and southern Italy. Blood Cells Mol Dis. 2003;31(Jul-Aug):57-62. doi: 10.1016/s1079-9796(03)00065-2.

56.

Shizukuda

Rosing

. Iron overload and arrhythmias: influence of confounding factors. J Arrhythmia. 2019;35(Aug):575-583. doi: 10.1002/joa3.12208

57.

Mercadante

, et al. Gastrointestinal iron excretion and reversal of iron excess in a mouse model of inherited iron excess. Haematologica. 2019;104(Apr):678-689. doi: 10.3324/haematol.2018.198382

58.

Hultcrantz

Angelin

Björn-Rasmussen

Ewerth

Einarsson

. Biliary excretion of iron and ferritin in idiopathic hemochromatosis. Gastroenterology. 1989;96(Jun):1539-1545. doi: 10.1016/0016-5085(89)90524-6.

59.

Wahidiyat

, et al. Urinary iron excretion for evaluating iron chelation efficacy in children with thalassemia major. Blood Cells Mol Dis. 2019;77(Jul):67-71. doi: 10.1016/j.bcmd.2019.03.007.

60.

Preza

, et al. Minihepcidins are rationally designed small peptides that mimic hepcidin activity in mice and may be useful for the treatment of iron overload. J Clin Invest. 2011;121(Dec):4880-4888. doi: 10.1172/JCI57693.

61.

Calzolari

, et al. Transferrin receptor 2 is frequently and highly expressed in glioblastomas. Transl Oncol. 2010;3(Apr):123-134. doi: 10.1593/tlo.09274

62.

Libani

, et al. Decreased differentiation of erythroid cells exacerbates ineffective erythropoiesis in β-thalassemia. Blood. 2008;112(Aug):875-885. doi: 10.1182/blood-2007-12-126938

63.

Dussiot

, et al. An activin receptor IIA ligand trap corrects ineffective erythropoiesis in β-thalassemia. Nat Med. 2014;20(Apr):398-407. doi: 10.1038/nm.3468

64.

Piga

, et al. ACE-536 Increases hemoglobin and decreases transfusion burden and Serum ferritin in adults with Beta-thalassemia: preliminary results from a phase 2 study. Blood. 2014;124(Dec):53. https://doi.org/10.1182/blood.V124.21.53.53

65.

Motta

Scaramellini

Cappellini

. Expert opinion on investigational drugs investigational drugs in phase I and phase II clinical trials for thalassemia. Expert Opin Investig Drugs. 2017(26;7). DOI:10.1080/13543784.2017.1335709

66.

Wang

C-Y

Meynard

Lin

. The role of TMPRSS6/matriptase-2 in iron regulation and anemia. Front Pharmacol. 2014;5:114.

67.

Silvestri

, et al. The serine protease matriptase-2 (TMPRSS6) inhibits hepcidin activation by cleaving membrane hemojuvelin. Cell Metab. 2008;8(Dec):502-511. doi: 10.1016/j.cmet.2008.09.012.

68.

Bauer

, et al. A erythroid enhancer of BCL11A subject t genetic variation. Science. 2014;342(Oct 11):253-257. doi: 10.1126/science.1242088

69.

Viatte

, et al. Chronic hepcidin induction causes hyposideremia and alters the pattern of cellular iron accumulation in hemochromatotic mice. Blood. 2006;107(Apr):2952-2958. doi: 10.1182/blood-2005-10-4071

70.

Ramos

, et al. Minihepcidins prevent iron overload in a hepcidin-deficient mouse model of severe hemochromatosis. Blood. 2012;120(Nov):3829-3836. doi: 10.1182/blood-2012-07-440743.

71.

Xiao

, et al. Pharmacokinetics of anti-hepcidin monoclonal antibody Ab 12B9 m and hepcidin in cynomolgus monkeys. AAPS J. 2010;12(Dec):646-657. doi: 10.1208/s12248-010-9222-0

72.

Payen

Leboulch

. Advances in stem cell transplantation and gene therapy in the beta-hemoglobinopathies. Hematol Am Soc Hematol Educ Progr. 2012;2012(Dec):276-283. doi: 10.1182/asheducation-2012.1.276.

73.

Ezquer

Nunez

Rojas

Asenjo

Israel

. Hereditary hemochromatosis: an opportunity for gene therapy. Biol Res. 2006;39(Jun):113-124. doi: 10.4067/s0716-97602006000100014.

74.

Riaz

, et al. Serum ferritin levels, socio-demographic factors and desferrioxamine therapy in multi-transfused thalassemia major patients at a government tertiary care hospital of Karachi, Pakistan. BMC Res Notes. 2011;4(Aug):287. doi: 10.1186/1756-0500-4-287

75.

Knovich

Storey

Coffman

Torti

. Ferritin for the clinician. Blood Rev. 2009;23(May):95-104. doi: 10.1016/j.blre.2008.08.001