Non-syndromic congenital sideroblastic anaemia; phenotype, and genotype of 15 Indian patients.

Sideroblastic anaemias are a diverse group of congenital and acquired bone marrow failure disorders marked by the presence of ring sideroblasts, ineffective erythropoiesis, and systemic iron overload. Congenital Sideroblastic anaemia (CSA) is mainly caused by gene mutations associated with heme synthesis, iron-sulfur [Fe-S] cluster, and mitochondrial protein synthesis pathways. The most prevalent form of CSA is caused by mutations in the erythroid-specific -amino levulinate synthase (ALAS2) gene, which encodes the first enzyme in the heme synthesis pathway in red blood cells. The second most prevalent form of CSA is caused by a mutation in the Solute carrier family 25 member 38 (SLC25A38) gene, which codes for an erythroid-specific protein of the inner mitochondrial membrane. Additionally, 15-20 genes are altogether associated with CSA. In this study, we aim to identify the CSA patients, understand their genetics and establish genotype-phenotype correlation. We have identified fifteen cases of CSA using our targeted NGS (t-NGS) panel. The major clinical findings in our cohort were microcytic anaemia, ring sideroblasts, and dyserythropoiesis in the bone marrow. Currently, two patients are responsive to pyridoxine, while the rest are on blood transfusion support. We have identified ten variants in three different genes of CSA (ALAS2, SLC25A38 & HSPA9). Five patients harbour four hemizygous variants- p.Ala282Ser, p.Arg170Cys, p.Arg204Gln and exon 2 duplication in the ALAS2 gene. In seven patients, we have identified three homozygous mutations - p.Pro190Arg, p.Arg187Gln and p.Arg134Cys in the SLC25A38 gene. These mutations have been predominantly identified in the European population. Three patients revealed three heterozygous variants p. Thr463Ile, D326Tyr, and Arg284Trp in the HSPA9 gene. PyMoL was used to evaluate the functional effects of these variations and understand their effect on the structure of the protein. We believe that by combining a bone marrow examination with genetic sequencing, CSA patients can acquire a definitive diagnosis.

Single-cell profiling of ineffective erythropoiesis in a mouse model of ß-thalassaemia intermedia.

Beta-thalassaemia is an inherited haemoglobin disorder characterised by ineffective erythropoiesis (IE). The detailed pathogenesis of IE remains unclear. In this study, we used single-cell RNA sequencing (scRNA-seq) to examine IE in Th3/+ ß-thalassaemic mice. The results showed that the erythroid group was remarkably expanded, and genes involved in biological processes such as iron metabolism, haeme synthesis, protein folding, and response to heat were significantly upregulated from erythroid progenitors to reticulocytes in ß-thalassaemic mice. In particular, we identified a unique cell population close to reticulocytes, named ThReticulocytes, characterised by a high level of heat shock protein 70 (Hsp70) expression and dysregulation of iron metabolism and haeme synthesis signalling. Treatment of ß-thalassaemic mice with the haeme oxygenase inhibitor tin-mesoporphyrin effectively improved the iron disorder and IE, and the ThReticulocyte population and Hsp70 expression were significantly suppressed. This study revealed in detail the progression of IE at the single-cell level and possibly provided clues to find therapeutic targets in thalassaemia.

Up-regulation of microRNA 101-3p during erythropoiesis in ß-thalassemia/HbE.

Ineffective erythropoiesis is the main cause of anemia in ß-thalassemia. The crucial hallmark of ineffective erythropoiesis is the high proliferation of erythroblast. microRNA (miR/miRNA) involves several biological processes, including cell proliferation and erythropoiesis. miR-101 was widely studied and associated with proliferation in several types of cancer. However, the miR-101-3p has not been studied in ß-thalassemia/HbE. Therefore, this study aims to investigate the expression of miR-101-3p during erythropoiesis in ß-thalassemia/HbE. The results showed that miR-101-3p was upregulated in the erythroblast of ß-thalassemia/HbE patients on day 7, indicating that miR-101-3p may be involved with high proliferation in ß-thalassemia/HbE. Therefore, the mRNA targets of miR-101-3p including Rac1, SUB1, TET2, and TRIM44 were investigated to determine the mechanisms involved with high proliferation of ß-thalassemia/HbE erythroblasts. Rac1 expression was significantly reduced at day 11 in severe ß-thalassemia/HbE compared to normal controls and mild ß-thalassemia/HbE. SUB1 gene expression was significantly lower in severe ß-thalassemia/HbE compared to normal controls at day 9 of culture. For TET2 and TRIM44 expression, a significant difference was not observed among normal and ß-thalassemia/HbE. However, the high expression of miR-101-3p at day 7 and these target genes was not correlated, suggesting that this miRNA may regulate ineffective erythropoiesis in ß-thalassemia/HbE via other target genes.

New Cases and Mutations in SEC23B Gene Causing Congenital Dyserythropoietic Anemia Type II.

Congenital dyserythropoietic anemia type II (CDA II) is an inherited autosomal recessive blood disorder which belongs to the wide group of ineffective erythropoiesis conditions. It is characterized by mild to severe normocytic anemia, jaundice, and splenomegaly owing to the hemolytic component. This often leads to liver iron overload and gallstones. CDA II is caused by biallelic mutations in the SEC23B gene. In this study, we report 9 new CDA II cases and identify 16 pathogenic variants, 6 of which are novel. The newly reported variants in SEC23B include three missenses (p.Thr445Arg, p.Tyr579Cys, and p.Arg701His), one frameshift (p.Asp693GlyfsTer2), and two splicing variants (c.1512-2A>G, and the complex intronic variant c.1512-3delinsTT linked to c.1512-16_1512-7delACTCTGGAAT in the same allele). Computational analyses of the missense variants indicated a loss of key residue interactions within the beta sheet and the helical and gelsolin domains, respectively. Analysis of SEC23B protein levels done in patient-derived lymphoblastoid cell lines (LCLs) showed a significant decrease in SEC23B protein expression, in the absence of SEC23A compensation. Reduced SEC23B mRNA expression was only detected in two probands carrying nonsense and frameshift variants; the remaining patients showed either higher gene expression levels or no expression changes at all. The skipping of exons 13 and 14 in the newly reported complex variant c.1512-3delinsTT/c.1512-16_1512-7delACTCTGGAAT results in a shorter protein isoform, as assessed by RT-PCR followed by Sanger sequencing. In this work, we summarize a comprehensive spectrum of SEC23B variants, describe nine new CDA II cases accounting for six previously unreported variants, and discuss innovative therapeutic approaches for CDA II.

Morphological and Transcriptional Changes in Human Bone Marrow During Natural Plasmodium vivax Malaria Infections.

BACKGROUND: The presence of Plasmodium vivax malaria parasites in the human bone marrow (BM) is still controversial. However, recent data from a clinical case and experimental infections in splenectomized nonhuman primates unequivocally demonstrated the presence of parasites in this tissue. METHODS: In the current study, we analyzed BM aspirates of 7 patients during the acute attack and 42 days after drug treatment. RNA extracted from CD71+ cell suspensions was used for sequencing and transcriptomic analysis. RESULTS: We demonstrated the presence of parasites in all patients during acute infections. To provide further insights, we purified CD71+ BM cells and demonstrated dyserythropoiesis and inefficient erythropoiesis in all patients. In addition, RNA sequencing from 3 patients showed that genes related to erythroid maturation were down-regulated during acute infections, whereas immune response genes were up-regulated. CONCLUSIONS: This study thus shows that during P. vivax infections, parasites are always present in the BM and that such infections induced dyserythropoiesis and ineffective erythropoiesis. Moreover, infections induce transcriptional changes associated with such altered erythropoietic response, thus highlighting the importance of this hidden niche during natural infections.

Luspatercept, a two-edged sword in beta-thalassemia-associated paravertebral extramedullary hematopoietic masses (EHMs).

Paravertebral extramedullary hematopoietic masses (EHMs) account for up to 15% of extramedullary pseudotumors in beta-thalassemia (BT) and are most likely related to compensatory hematopoiesis. In most cases, pseudotumors are incidentally detected, as the majority of patients are asymptomatic. Since June 2020, luspatercept is approved for the treatment of patients with BT who require regular red blood cell transfusions. Data addressing the safety and efficacy of luspatercept in patients with BT-associated EHMs are pending. To date (May 2022), paravertebral EHMs were observed in two asymptomatic patients out of currently 43 adult patients with BT registered at the Adult Hemoglobinopathy Outpatient Unit of the University Hospital Essen, Germany. In one of them, a paravertebral EHM was diagnosed more than 10 years prior to referral. Throughout observation time, treatment with luspatercept was associated with a clinically significant reduction in transfusion burden while allowing to maintain a baseline hemoglobin concentration of ≥10 g/dL aiming to suppress endogenous (ineffective) erythropoiesis associated with BT. Considering the rarity of paravertebral EHMs in BT, luspatercept might potentially represent a novel therapeutic option for these often-serious disease-associated complications. However, appropriate follow-up investigations are recommended to detect (early) treatment failures secondary to an undesired luspatercept-associated erythroid expansion.

Beta-thalassemia and the advent of new interventions beyond transfusion and iron chelation.

Beta-thalassaemia, including sickle cell anaemia and thalassaemia E, is most common in developing countries in tropical and subtropic regions. Because carriers have migrated there owing to demographic migration, ß-thalassaemia can now be detected in areas other than malaria-endemic areas. Every year, an estimated 300 000-500 000 infants, the vast majority of whom are from developing countries, are born with a severe haemoglobin anomaly. Currently, some basic techniques, which include iron chelation therapy, hydroxyurea, blood transfusion, splenectomy and haematopoietic stem cell transplantation, are being used to manage thalassaemia patients. Despite being the backbone of treatment, traditional techniques have several drawbacks and limitations. Ineffective erythropoiesis, correction of globin chain imbalance and adjustment of iron metabolism are some of the innovative treatment methods that have been developed in the care of thalassaemia patients in recent years. Moreover, regulating the expression of B-cell lymphoma/leukaemia 11A and sex-determining region Y-box through the enhanced expression of micro RNAs can also be considered putative targets for managing haemoglobinopathies. This review focuses on the biological basis of ß-globin gene production, the pathophysiology of ß-thalassaemia and the treatment options that have recently been introduced.

Neonatal hemochromatosis with εγδß-thalassemia: a case report and analysis of serum iron regulators.

BACKGROUND: Neonatal hemochromatosis causes acute liver failure during the neonatal period, mostly due to gestational alloimmune liver disease (GALD). Thalassemia causes hemolytic anemia and ineffective erythropoiesis due to mutations in the globin gene. Although neonatal hemochromatosis and thalassemia have completely different causes, the coexistence of these diseases can synergistically exacerbate iron overload. We report that a newborn with εγδß-thalassemia developed neonatal hemochromatosis, which did not respond to iron chelators and rapidly worsened, requiring living-donor liver transplantation. CASE PRESENTATION: A 1-day-old Japanese boy with hemolytic anemia and targeted red blood cells was diagnosed with εγδß-thalassemia by genetic testing, and required frequent red blood cell transfusions. At 2 months after birth, exacerbation of jaundice, grayish-white stool, and high serum ferritin levels were observed, and liver biopsy showed iron deposition in hepatocytes and Kupffer cells. Magnetic resonance imaging scans showed findings suggestive of iron deposits in the liver, spleen, pancreas, and bone marrow. The total amount of red blood cell transfusions administered did not meet the criteria for post-transfusion iron overload. Administration of an iron-chelating agent was initiated, but iron overload rapidly progressed to liver failure without improvement in jaundice and liver damage. He underwent living-donor liver transplantation from his mother, after which iron overload disappeared, and no recurrence of iron overload was observed. Immunohistochemical staining for C5b-9 in the liver was positive. Serum hepcidin levels were low and serum growth differentiation factor-15 levels were high prior to living-donor liver transplantation. CONCLUSIONS: We reported that an infant with εγδß-thalassemia developed NH due to GALD, and that coexistence of ineffective erythropoiesis in addition to erythrocyte transfusions may have exacerbated iron overload. Low serum hepcidin levels, in this case, might have been caused by decreased hepcidin production arising from fetal liver damage due to neonatal hemochromatosis and increased hepcidin-inhibiting hematopoietic mediators due to the ineffective hematopoiesis observed in thalassemia.

The Roles of Mitophagy and Autophagy in Ineffective Erythropoiesis in ß-Thalassemia.

ß-Thalassemia is one of the most common genetically inherited disorders worldwide, and it is characterized by defective ß-globin chain synthesis leading to reduced or absent ß-globin chains. The excess α-globin chains are the key factor leading to the death of differentiating erythroblasts in a process termed ineffective erythropoiesis, leading to anemia and associated complications in patients. The mechanism of ineffective erythropoiesis in ß-thalassemia is complex and not fully understood. Autophagy is primarily known as a cell recycling mechanism in which old or dysfunctional proteins and organelles are digested to allow recycling of constituent elements. In late stage, erythropoiesis autophagy is involved in the removal of mitochondria as part of terminal differentiation. Several studies have shown that autophagy is increased in earlier erythropoiesis in ß-thalassemia erythroblasts, as compared to normal erythroblasts. This review summarizes what is known about the role of autophagy in ß-thalassemia erythropoiesis and shows that modulation of autophagy and its interplay with apoptosis may provide a new therapeutic route in the treatment of ß-thalassemia. Literature was searched and relevant articles were collected from databases, including PubMed, Scopus, Prospero, Clinicaltrials.gov, Google Scholar, and the Google search engine. Search terms included: ß-thalassemia, ineffective erythropoiesis, autophagy, novel treatment, and drugs during the initial search. Relevant titles and abstracts were screened to choose relevant articles. Further, selected full-text articles were retrieved, and then, relevant cross-references were scanned to collect further information for the present review.

Erythropoiesis and Malaria, a Multifaceted Interplay.

One of the major pathophysiologies of malaria is the development of anemia. Although hemolysis and splenic clearance are well described as causes of malarial anemia, abnormal erythropoiesis has been observed in malaria patients and may contribute significantly to anemia. The interaction between inadequate erythropoiesis and Plasmodium parasite infection, which partly occurs in the bone marrow, has been poorly investigated to date. However, recent findings may provide new insights. This review outlines clinical and experimental studies describing different aspects of ineffective erythropoiesis and dyserythropoiesis observed in malaria patients and in animal or in vitro models. We also highlight the various human and parasite factors leading to erythropoiesis disorders and discuss the impact that Plasmodium parasites may have on the suppression of erythropoiesis.

Non-Transfusion-Dependent Thalassemia: A Panoramic Review.

Non-transfusion-dependent thalassemia (NTDT) has been considered less severe than its transfusion-dependent variants. The most common forms of NTDT include ß-thalassemia intermedia, hemoglobin E/beta thalassemia, and hemoglobin H disease. Patients with NTDT develop several clinical complications, despite their regular transfusion independence. Ineffective erythropoiesis, iron overload, and hypercoagulability are pathophysiological factors that lead to morbidities in these patients. Therefore, an early and accurate diagnosis of NTDT is essential to ascertaining early interventions. Currently, several conventional management options are available, with guidelines suggested by the Thalassemia International Federation, and novel therapies are being developed in light of the advancement of the understanding of this disease. This review aimed to increase clinicians' awareness of NTDT, from its basic medical definition and genetics to its pathophysiology. Specific complications to NTDT were reviewed, along with the risk factors for its development. The indications of different therapeutic options were outlined, and recent advancements were reviewed.

Erythroferrone structure, function, and physiology: Iron homeostasis and beyond.

Erythroferrone (ERFE) is the main erythroid regulator of hepcidin, the homeostatic hormone controlling plasma iron levels and total body iron. When the release of erythropoietin from the kidney stimulates the production of new red blood cells, it also increases the synthesis of ERFE in bone marrow erythroblasts. Increased ERFE then suppresses hepcidin synthesis, thereby mobilizing cellular iron stores for use in heme and hemoglobin synthesis. Recent mechanistic studies have shown that ERFE suppresses hepcidin transcription by inhibiting bone morphogenetic protein signaling in hepatocytes. In ineffective erythropoiesis, pathological overproduction of ERFE by an expanded population of erythroblasts suppresses hepcidin and causes iron overload, even in non-transfused patients. ERFE may be a useful biomarker of ineffective erythropoiesis and an attractive target for treating its systemic effects.

Marrow Fat Content and Composition in ß-Thalassemia: A Study using 1 H-MRS.

BACKGROUND: ß-thalassemia is a genetic disease that causes abnormal production of red blood cells (ineffective erythropoiesis, IE). IE is a condition known to change bone marrow composition. PURPOSE: To evaluate the effect of IE on the marrow fat content and fat unsaturation levels in the proximal femur using 1 H-MRS. STUDY TYPE: Prospective. SUBJECTS: Twenty-three subjects were included in this study, seven control and 16 ß-thalassemia subjects. FIELD STRENGTH/SEQUENCE: 3.0T; stimulated echo acquisition Mode (STEAM); magnetic resonance spectroscopy (MRS) sequence. ASSESSMENT: Multiecho MRS scans were performed in four regions of the proximal left femur of each subject, that is, diaphysis, femoral neck, femoral head, and greater trochanter. The examined regions were grouped into red (diaphysis and femoral neck) and yellow marrow regions (femoral head and greater trochanter). STATISTICAL TESTS: The Jonckheere-Terpstra test was used to evaluate the impact of increasing disease severity on bone marrow fat fraction (BMFF), marrow conversion index, and fat unsaturation index (UI). Pairwise comparison analysis was performed when a significant trend (P < 0.05) was found. K-means clustering analysis was used to examine the clusters observed when BMFF in the red and yellow regions were studied (diaphysis against greater trochanter). RESULTS: BMFF showed a significant decreasing trend with increasing disease severity in both red (TJT = 109.00, z = -4.414, P < 0.05) and yellow marrow regions (TJT = 108.00, z = -4.438, P < 0.05). The opposite trend was observed in UI in both bone marrow regions (red marrow: TJT = 180.5, z = 3.515, P < 0.05; yellow marrow: TJT = 155.0, z = 2.282, P = 0.05). Three distinct forms of marrow adipogenesis were found when plotting BMFF diaphysis against BMFF greater trochanter: 1) normal (centroid: 80.4%, 66.6%), 2) partial disruption (centroid: 51.1%, 16.6%), and 3) total disruption (centroid: 2.6%, 1.6%). DATA CONCLUSION: ß-thalassemia is associated with decreased marrow fat, and increased marrow fat unsaturation level. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 3.

The role of iron in mediating testosterone's effects on erythropoiesis in mice.

Testosterone stimulates iron-dependent erythropoiesis and suppresses hepcidin. To clarify the role of iron in mediating testosterone's effects on erythropoiesis, we induced iron deficiency in mice by feeding low iron diet. Iron-replete and iron-deficient mice were treated weekly with testosterone propionate or vehicle for 3 weeks. Testosterone treatment increased red cell count in iron-replete mice, but, surprisingly, testosterone reduced red cell count in iron-deficient mice. Splenic stress erythropoiesis was stimulated in iron-deficient mice relative to iron-replete mice, and further increased by testosterone treatment, as indicated by the increase in red pulp area, the number of nucleated erythroblasts, and expression levels of TfR1, GATA1, and other erythroid genes. Testosterone treatment of iron-deficient mice increased the ratio of early-to-late erythroblasts in the spleen and bone marrow, and serum LDH level, consistent with ineffective erythropoiesis. In iron-deficient mice, erythropoietin levels were higher but erythropoietin-regulated genes were generally downregulated relative to iron-replete mice, suggesting erythropoietin resistance. Conclusion: Testosterone treatment stimulates splenic stress erythropoiesis in iron-replete as well as iron-deficient mice. However, testosterone worsens anemia in iron-deficient mice because of ineffective erythropoiesis possibly due to erythropoietin resistance associated with iron deficiency. Iron plays an important role in mediating testosterone's effects on erythropoiesis.

Efficacy and safety of ruxolitinib in ineffective erythropoiesis suppression as a pretransplantation treatment for pediatric patients with beta-thalassemia major.

BACKGROUND: Ineffective erythropoiesis (IE) is the most prominent feature of transfusion-dependent beta-thalassemia (TDT), which leads to extramedullary hemopoiesis. The rejection rate in allogeneic hematopoietic stem cell transplantation (HSCT) is high in heavily transfused patients with TDT accompanied by prominent IE. Therefore, a pretransplantation treatment bridging to HSCT is often used to reduce allosensitization and IE. Ruxolitinib is a JAK-1/JAK-2 inhibitor and has showed its efficacy in suppressing IE and the immune system. A previously published study on RUX in adult patients with TDT has revealed that this treatment significantly reduces spleen size and is well tolerated. PROCEDURE: Ten patients (5-14 years old) with TDT and an enlarged spleen were enrolled. The dose of ruxolitinib was adjusted for age: for patients <11 years: 40-100 mg/m2 total daily dose and for patients >11 years: 20-30 mg/m2 total daily dose. HSCT was performed in 8 of 10 patients. RESULTS: After the first 3 months of ruxolitinib therapy, spleen volume decreased in 9 of 10 cases by 9.1%-67.5% (M = 35.4%) compared with the initial size (P = 0.003). The adverse events of ruxolitinib (infectious complications, moderate thrombocytopenia, and headache) were successfully managed by reducing the dose. The outcomes of HSCT were favorable in seven of eight cases. CONCLUSION: Ruxolitinib is promising as a short-term pre-HSCT treatment for pediatric patients with TDT and pronounced IE.

Association of the Degree of Erythroid Expansion and Maturation Arrest with the Clinical Severity of ß0-Thalassemia/Hemoglobin E Patients.

INTRODUCTION: ß-Thalassemia/hemoglobin E represents one-half of all the clinically severe ß-thalassemias worldwide. Despite similar genetic backgrounds, patients show clinical heterogeneity ranging from nearly asymptomatic to transfusion-dependent thalassemia. The underlying disease modifying factors remain largely obscure. METHODS: To elucidate the correlation between ineffective erythropoiesis and ß0-thalassemia/hemoglobin E (HbE) disease severity, in vitro culture of erythroid cells derived from patients with different clinical symptoms was established. Cell proliferation, viability, and differentiation were investigated. To identify potential molecular mechanisms leading to the arrested erythroid maturation, the expression levels of erythropoiesis modifying factors were measured. RESULTS: The ß0-thalassemia/HbE cells exhibited enhanced proliferation, limited differentiation, and impaired erythroid terminal maturation but did not show accelerated erythroblast differentiation and increased cell death. Erythroblasts derived from mild patients showed the highest proliferation rate with a faster cell division time, while erythroblasts derived from severe patients displayed extremely delayed erythroid maturation. Downregulation of growth differentiation factor 11 and FOXO3a was observed in mild ß0-thalassemia/HbE erythroblasts, while upregulation of heat shock protein 70 and activin receptor 2A was revealed in severe erythroblasts. DISCUSSION/CONCLUSION: The degree of erythroid expansion and maturation arrest contributes to the severity of ß0-thalassemia/HbE patients, accounting for the disease heterogeneity. The findings suggest a restoration of erythroid maturation as a promising targeted therapy for severe patients.

GDF-15 negatively regulates excess erythropoiesis and its overexpression is involved in erythroid hyperplasia.

Growth differentiation factor-15 (GDF-15) is a member of TGF-ß superfamily. Among hematopoietic cells, this factor is mainly produced by erythroid series and is recently considered a biomarker of ineffective erythropoiesis (IE). Whether IE induces enhanced GDF-15 expression or is prompted by it, has remained elusive. In this study we investigated how high levels of GDF-15 contribute to IE-associated erythroid dysplasia. We assessed mRNA levels of GDF-15 during erythroid maturation as well as in patients with IE using qRT-PCR. Later, the erythroid colony-forming capacity of GDF-15-treated hematopoietic stem cells (HSCs) was evaluated by CFC assay. Any effect of elevated levels of GDF-15 on erythroid maturation was ultimately examined by expression analysis of erythroid-associated transcription factors and flow cytometry analysis of CD235a expression. GDF-15 mRNA expression increased during erythroid differentiation and also in ß-thalassemia and MDS patients which was directly correlated with erythropoiesis severity. Treating the cells with high GDF-15 concentration (50 ng/ml) resulted in an approximate 30% decline in the capacity of erythroid colony formation of HSCs and CD235a positive cells. Additionally, erythroid-specific transcription factors showed significant down-regulation in the early stages of erythroid differentiation. According to the expression level of GDF-15 and the role it plays in the erythroid system, high-levels of this factor could be an auto-modulatory mechanism to control the excessive production of erythroid cells.

The Interplay between Drivers of Erythropoiesis and Iron Homeostasis in Rare Hereditary Anemias: Tipping the Balance.

Rare hereditary anemias (RHA) represent a group of disorders characterized by either impaired production of erythrocytes or decreased survival (i.e., hemolysis). In RHA, the regulation of iron metabolism and erythropoiesis is often disturbed, leading to iron overload or worsening of chronic anemia due to unavailability of iron for erythropoiesis. Whereas iron overload generally is a well-recognized complication in patients requiring regular blood transfusions, it is also a significant problem in a large proportion of patients with RHA that are not transfusion dependent. This indicates that RHA share disease-specific defects in erythroid development that are linked to intrinsic defects in iron metabolism. In this review, we discuss the key regulators involved in the interplay between iron and erythropoiesis and their importance in the spectrum of RHA.

The Oral Ferroportin Inhibitor VIT-2763 Improves Erythropoiesis without Interfering with Iron Chelation Therapy in a Mouse Model of ß-Thalassemia.

In ß-thalassemia, ineffective erythropoiesis leads to anemia and systemic iron overload. The management of iron overload by chelation therapy is a standard of care. However, iron chelation does not improve the ineffective erythropoiesis. We recently showed that the oral ferroportin inhibitor VIT-2763 ameliorates anemia and erythropoiesis in the Hbbth3/+ mouse model of ß-thalassemia. In this study, we investigated whether concurrent use of the iron chelator deferasirox (DFX) and the ferroportin inhibitor VIT-2763 causes any pharmacodynamic interactions in the Hbbth3/+ mouse model of ß-thalassemia. Mice were treated with VIT-2763 or DFX alone or with the combination of both drugs once daily for three weeks. VIT-2763 alone or in combination with DFX improved anemia and erythropoiesis. VIT-2763 alone decreased serum iron and transferrin saturation (TSAT) but was not able to reduce the liver iron concentration. While DFX alone had no effect on TSAT and erythropoiesis, it significantly reduced the liver iron concentration alone and in the presence of VIT-2763. Our results clearly show that VIT-2763 does not interfere with the iron chelation efficacy of DFX. Furthermore, VIT-2763 retains its beneficial effects on improving ineffective erythropoiesis when combined with DFX in the Hbbth3/+ mouse model. In conclusion, co-administration of the oral ferroportin inhibitor VIT-2763 and the iron chelator DFX is feasible and might offer an opportunity to improve both ineffective erythropoiesis and iron overload in ß-thalassemia.

Ineffective Erythropoiesis in ß-Thalassaemia: Key Steps and Therapeutic Options by Drugs.

ß-thalassaemia is a rare genetic condition caused by mutations in the ß-globin gene that result in severe iron-loading anaemia, maintained by a detrimental state of ineffective erythropoiesis (IE). The role of multiple mechanisms involved in the pathophysiology of the disease has been recently unravelled. The unbalanced production of α-globin is a major source of oxidative stress and membrane damage in red blood cells (RBC). In addition, IE is tightly linked to iron metabolism dysregulation, and the relevance of new players of this pathway, i.e., hepcidin, erythroferrone, matriptase-2, among others, has emerged. Advances have been made in understanding the balance between proliferation and maturation of erythroid precursors and the role of specific factors in this process, such as members of the TGF-ß superfamily, and their downstream effectors, or the transcription factor GATA1. The increasing understanding of IE allowed for the development of a broad set of potential therapeutic options beyond the current standard of care. Many candidates of disease-modifying drugs are currently under clinical investigation, targeting the regulation of iron metabolism, the production of foetal haemoglobin, the maturation process, or the energetic balance and membrane stability of RBC. Overall, they provide tools and evidence for multiple and synergistic approaches that are effectively moving clinical research in ß-thalassaemia from bench to bedside.