The β-thalassemias are inherited genetic disorders affecting the hematopoietic system. In β-thalassemias, more than 350 mutations of the adult β-globin gene cause the low or absent production of adult hemoglobin (HbA). A clinical parameter affecting the physiology of erythroid cells is the excess of free α-globin. Possible experimental strategies for a reduction in excess free α-globin chains in β-thalassemia are CRISPR-Cas9-based genome editing of the β-globin gene, forcing \"de novo\" HbA production and fetal hemoglobin (HbF) induction. In addition, a reduction in excess free α-globin chains in β-thalassemia can be achieved by induction of the autophagic process. This process is regulated by the Unc-51-like kinase 1 (Ulk1) gene. The interplay with the PI3K/Akt/TOR pathway, with the activity of the α-globin stabilizing protein (AHSP) and the involvement of microRNAs in autophagy and Ulk1 gene expression, is presented and discussed in the context of identifying novel biomarkers and potential therapeutic targets for β-thalassemia.

Hereditary dyserythropoietic anemias, or congenital dyserythropoietic anemias (CDAs), are rare disorders disrupting normal erythroid lineage development, resulting in ineffective erythropoiesis and monolinear cytopenia. CDAs include three main types (I, II, III), transcription-factor-related forms, and syndromic forms. The widespread use of next-generation sequencing in the last decade has unveiled novel causative genes and unexpected genotype-phenotype correlations. The discovery of the genetic defects underlying the CDAs not only facilitates accurate diagnosis but also enhances understanding of CDA pathophysiology. Notable advancements include identifying a hepatic-specific role of the SEC23B loss-of-function in iron metabolism dysregulation in CDA II, deepening CDIN1 dysfunction during erythroid differentiation, and uncovering a recessive CDA III form associated with RACGAP1 variants. Current treatments primarily rely on supportive measures tailored to disease severity and clinical features. Comparative studies with pyruvate kinase deficiency have illuminated new therapeutic avenues by elucidating iron dyshomeostasis and dyserythropoiesis mechanisms. We herein discuss recent progress in diagnostic methodologies, novel gene discoveries, and enhanced comprehension of CDA pathogenesis and molecular genetics.

Aging is characterized by increased oxidation and reduced efficiency of cytoprotective mechanisms. Nuclear factor erythroid-2-related factor (Nrf2) is a key transcription factor, controlling the expression of multiple antioxidant proteins. Here, we show that Nrf2-/- mice displayed an age-dependent anemia, due to the combined contributions of reduced red cell lifespan and ineffective erythropoiesis, suggesting a role of Nrf2 in erythroid biology during aging. Mechanistically, we found that the expression of antioxidants during aging is mediated by activation of Nrf2 function by peroxiredoxin-2. The absence of Nrf2 resulted in persistent oxidation and overactivation of adaptive systems such as the unfolded protein response (UPR) system and autophagy in Nrf2-/- mouse erythroblasts. As Nrf2 is involved in the expression of autophagy-related proteins such as autophagy-related protein (Atg) 4-5 and p62, we found impairment of late phase of autophagy in Nrf2-/- mouse erythroblasts. The overactivation of the UPR system and impaired autophagy drove apoptosis of Nrf2-/- mouse erythroblasts via caspase-3 activation. As a proof of concept for the role of oxidation, we treated Nrf2-/- mice with astaxanthin, an antioxidant, in the form of poly (lactic-co-glycolic acid) (PLGA)-loaded nanoparticles (ATS-NPs) to improve its bioavailability. ATS-NPs ameliorated the age-dependent anemia and decreased ineffective erythropoiesis in Nrf2-/- mice. In summary, we propose that Nrf2 plays a key role in limiting age-related oxidation, ensuring erythroid maturation and growth during aging.

In Guangxi, Hainan, and Fujian Province in southern China, β-thalassemia is a frequent monogenic hereditary disorder that is primarily defined by hemolytic anemia brought on by inefficient erythropoiesis. It has been found that ineffective erythropoiesis in β-thalassemia is closely associated with a high accumulation of Reactive oxygen species, a product of oxidative stress, in erythroid cells. During recent years, ferroptosis is an iron-dependent lipid peroxidation that involves abnormalities in lipid and iron metabolism as well as reactive oxygen species homeostasis. It is a recently identified kind of programmed cell death. β-thalassemia patients experience increased iron release from reticuloendothelial cells and intestinal absorption of iron, ultimately resulting in iron overload. Additionally, the secretion of Hepcidin is inhibited in these patients. What counts is both ineffective erythropoiesis and ferroptosis in β-thalassemia are intricately linked to the iron metabolism and Reactive oxygen species homeostasis. Consequently, to shed further light on the pathophysiology of β-thalassemia and propose fresh ideas for its therapy, this paper reviews ferroptosis, ineffective erythropoiesis, and the way they interact.

Congenital sideroblastic anemia (CSA) is a group of disorders caused by different genetic mutations that result in low iron utilization and ineffective erythropoiesis. Current treatments are limited, and some patients do not respond to vitamin B6 therapy. Luspatercept is a novel erythropoietic maturation agent approved for adult β-thalassemia and Myelodysplastic syndromes with ring sideroblasts (MDS-RS) associated with ineffective erythropoiesis. Here we report 2 patients with CSA due to mutations in ALAS2 and SLC25A38 genes who became unresponsive after a period of treatment with vitamin B6 and iron chelators but achieved transfusion independence and a markedly reduced spleen after combination with luspatercept.

Myelodysplastic syndrome (MDS) is a heterogeneous group of bone marrow stem cell disorders characterized by ineffective hematopoiesis and cytopenias, most commonly anemia. Red cell transfusion therapy for anemia in MDS results in iron overload, correlating with reduced overall survival. Whether the treatment of iron overload benefits MDS patients remains controversial. We evaluate underlying iron-related pathophysiology and the effect of iron chelation using deferiprone on erythropoiesis in NUP98-HOXD13 transgenic mice, a highly penetrant well-established MDS mouse model. Our results characterize an iron overload phenotype with aberrant erythropoiesis in these mice which was reversed by deferiprone-treatment. Serum erythropoietin levels decreased while erythroblast erythropoietin receptor expression increased in deferiprone-treated MDS mice. We demonstrate, for the first time, normalized expression of the iron chaperones Pcbp1 and Ncoa4 and increased ferritin stores in late-stage erythroblasts from deferiprone-treated MDS mice, evidence of aberrant iron trafficking in MDS erythroblasts. Importantly, erythroblast ferritin is increased in response to deferiprone, correlating with decreased erythroblast ROS. Finally, we confirmed increased expression of genes involved in iron uptake, sensing, and trafficking in stem and progenitor cells from MDS patients. Taken together, our findings provide evidence that erythroblast-specific iron metabolism is a novel potential therapeutic target to reverse ineffective erythropoiesis in MDS.

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Ineffective erythropoiesis is the main cause of anemia in β-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 β-thalassemia/HbE. Therefore, this study aims to investigate the expression of miR-101-3p during erythropoiesis in β-thalassemia/HbE. The results showed that miR-101-3p was upregulated in the erythroblast of β-thalassemia/HbE patients on day 7, indicating that miR-101-3p may be involved with high proliferation in β-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 β-thalassemia/HbE erythroblasts. Rac1 expression was significantly reduced at day 11 in severe β-thalassemia/HbE compared to normal controls and mild β-thalassemia/HbE. SUB1 gene expression was significantly lower in severe β-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 β-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 β-thalassemia/HbE via other target genes.

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.

Over the past decade, evidence has been mounting on the detrimental clinical sequelae of untreated anemia in patients with non-transfusion-dependent β-thalassemia (NTDT). There are no pharmacologic agents that are specifically approved for the management of anemia in NTDT, and available options such as splenectomy, transfusion therapy, and hydroxyurea each come with their own shortcomings, especially for long-term use. Luspatercept is an erythroid maturation agent that has been evaluated in a Phase 2, randomized trial and showed a significant benefit in raising hemoglobin level by at least 1 g/dL in adults with NTDT and a baseline hemoglobin level ≤10 g/dL. These data led to luspatercept\'s approval by the European Commission for the treatment of anemia in adults with NTDT and presents the first evidence-based approach for a novel agent that is able to ameliorate anemia in this patient population.