Distal enhancers commonly contact target promoters via chromatin looping. In erythroid cells, the locus control region (LCR) contacts β-type globin genes in a developmental stage-specific manner ...to stimulate transcription. Previously, we induced LCR-promoter looping by tethering the self-association domain (SA) of Ldb1 to the β-globin promoter via artificial zinc fingers. Here, we show that targeting the SA to a developmentally silenced embryonic globin gene in adult murine erythroblasts triggers its transcriptional reactivation. This activity depends on the LCR, consistent with an LCR-promoter looping mechanism. Strikingly, targeting the SA to the fetal γ-globin promoter in primary adult human erythroblasts increases γ-globin promoter-LCR contacts, stimulating transcription to approximately 85% of total β-globin synthesis, with a reciprocal reduction in adult β-globin expression. Our findings demonstrate that forced chromatin looping can override a stringent developmental gene expression program and suggest a novel approach to control the balance of globin gene transcription for therapeutic applications.
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•Tethering Ldb1 to embryonic or fetal globin genes activates them in adult erythroblasts•Activation of embryonic or fetal globin genes reduces adult type globin expression•Tethered Ldb1 reconfigures enhancer-promoter contacts commensurate with gene expression•Forced chromatin looping presents a novel therapeutic strategy for sickle cell anemia
In adult erythroblasts, forced juxtaposition of the distal enhancer of the β-globin locus with embryonic or fetal globin gene promoters leads to their reactivation, suggesting a potential new strategy for the treatment of β-hemoglobinopathies, including sickle cell anemia.
Therapeutic options for rare congenital (hemoglobinopathies, membrane and enzyme defects, congenital dyserythropoietic anemia) and acquired anemias warm autoimmune hemolytic anemia (wAIHA), cold ...agglutinin disease CAD, paroxysmal nocturnal hemoglobinuria (PNH), and aplastic anemia (AA) are rapidly expanding. The use of luspatercept, mitapivat and etavopivat in beta-thalassemia and pyruvate kinase deficiency (PKD) improves transfusion dependence, alleviating iron overload and long-term complications. Voxelotor, mitapivat, and etavopivat reduce vaso-occlusive crises in sickle cell disease (SCD). Gene therapy represents a fascinating approach, although patient selection, the toxicity of the conditioning regimens, and the possible long-term safety are still open issues. For acquired forms, wAIHA and CAD will soon benefit from targeted therapies beyond rituximab, including B-cell/plasma cell targeting agents (parsaclisib, rilzabrutinib, and isatuximab for wAIHA), complement inhibitors (pegcetacoplan and sutimlimab for CAD, ANX005 for wAIHA with complement activation), and inhibitors of extravascular hemolysis in the reticuloendothelial system (fostamatinib and FcRn inhibitors in wAIHA). PNH treatment is moving from the intravenous anti-C5 eculizumab to its long-term analog ravulizumab, and to subcutaneous and oral proximal inhibitors (anti-C3 pegcetacoplan, factor D and factor B inhibitors danicopan and iptacopan). These drugs have the potential to improve patient convenience and ameliorate residual anemia, although patient compliance becomes pivotal, and long-term safety requires further investigation. Finally, the addition of eltrombopag significantly ameliorated AA outcomes, and data regarding the alternative agent romiplostim are emerging. The accelerated evolution of treatment strategies will need further effort to identify the best candidate for each treatment in the precision medicine era.
Patients with β thalassemia intermedia can have substantial iron overload, irrespectively of their transfusion status, secondary to increased intestinal iron absorption. This study evaluates whether ...iron overload in patients with β thalassemia intermedia is associated with morbidity.
This was a cross-sectional study of 168 patients with β thalassemia intermedia treated at two centers in Lebanon and Italy. Data on demographics, splenectomy status, transfusion status, and presence of co-morbidities were retrieved. Laboratory values of serum ferritin, fetal and total hemoglobin levels, as well as platelet and nucleated red blood cell counts were also obtained. Iron burden was determined directly by measuring liver iron concentration using magnetic resonance imaging. Patients were subdivided according to transfusion and splenectomy status into groups with phenotypes of different severity.
The mean age of the patients was 35.2 ± 12.6 years and 42.9% of them were male. The mean liver iron concentration was 8.4 ± 6.7 mg Fe/g dry weight. On multivariate logistic regression analysis, after adjusting for age, gender, splenectomy status, transfusion status, and laboratory indices, an increase in 1 mg Fe/g dry weight liver iron concentration was independently and significantly associated with higher odds of thrombosis, pulmonary hypertension, hypothyroidism, osteoporosis, and hypogonadism. A liver iron concentration of at least 7 and at least 6 mg Fe/g dry weight were the best thresholds for discriminating the presence and absence of vascular and endocrine/bone morbidities, respectively (area under the receiver-operating characteristic curve: 0.72, P<0.001). Elevated liver iron concentration was associated with an increased rate of morbidity in patients with phenotypes of all severity, with a steeper increase in the rate of vascular morbidity being attributed to aging, and an earlier appearance of endocrine and bone disease.
Elevated liver iron concentration in patients with β thalassemia intermedia is a marker of increased vascular, endocrine, and bone disease.
A significant amount of attention has recently been devoted to the mechanisms involved in hemoglobin (Hb) switching, as it has previously been established that the induction of fetal hemoglobin (HbF) ...production in significant amounts can reduce the severity of the clinical course in diseases such as β-thalassemia and sickle cell disease (SCD). While the induction of HbF using lentiviral and genome-editing strategies has been made possible, they present limitations. Meanwhile, progress in the use of pharmacologic agents for HbF induction and the identification of novel HbF-inducing strategies has been made possible as a result of a better understanding of γ-globin regulation. In this review, we will provide an update on all current pharmacological inducer agents of HbF in β-thalassemia and SCD in addition to the ongoing research into other novel, and potentially therapeutic, HbF-inducing agents.
Inherited hemoglobin disorders, including beta-thalassemia (BT) and sickle-cell disease (SCD) are the most common monogenic diseases worldwide, with a global carrier frequency of over 5%. With ...migration they are becoming more common worldwide, making their management and care an increasing concern for health care systems.
BT is characterized by an imbalance in the α/β-globin chain ratio, ineffective erythropoiesis, chronic hemolytic anemia, and compensatory haemopoietic expansion. Globally, there are over 25,000 births each year with transfusion-dependent thalassemia (TDT). The current available treatment for TDT is lifelong transfusions and iron chelation therapy or allogenic bone marrow as curative option. SCD affects 300 million people worldwide and severely impacts the quality of life of patients, who experience unpredictable, recurrent acute and chronic severe pain, stroke, infections, pulmonary disease, kidney disease, retinopathy, and other complications. While survival has been dramatically extended, quality of life is markedly reduced by disease- and treatment-associated morbidity.
The development of safe, tissue specific and efficient vectors, and efficient gene editing technologies have led to the development of several gene therapy trials for BT and SCD. Yet, the complexity of the approach presents its hurdles. Fundamental factors at play include the requirement for myeloablation on a patient with a benign disease, the age of the patient and consequent bone marrow microenvironment. A successful path from proof-of-concept studies to commercialization must render gene therapy a sustainable and accessible approach for a large number of patients. Furthermore, the cost of these therapies is a considerable challenge for the health care system. While new promising therapeutic options are emerging and many others are on the pipeline5, gene therapy can potentially cure patients. We herein provide an overview of the most recent potentially curative therapies for hemoglobinopathies and a summary of the challenges that these approaches entail.
Innovative Treatments for Rare Anemias Cappellini, Maria Domenica; Marcon, Alessia; Fattizzo, Bruno ...
HemaSphere,
June 2021, 2021-06-00, 20210601, 2021-06-01, Letnik:
5, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Rare anemias (RA) are mostly hereditary disorders with low prevalence and a broad spectrum of clinical severity, affecting different stages of erythropoiesis or red blood cell components. RA often ...remains underdiagnosed or misdiagnosed, and treatment options have been limited to supportive care for many years. During the last decades, the elucidation of the molecular mechanisms underlying several RA paved the way for developing new treatments. Innovative treatments other than supportive care and allogeneic bone marrow transplantation are currently in clinical trials for β‐thalassemias, sickle cell disease (SCD), and congenital hemolytic anemias. Recently, luspatercept, an activin receptor ligand trap targeting ineffective erythropoiesis, has been approved as the first pharmacological treatment for transfusion‐dependent β‐thalassemia. L‐glutamine, voxelotor, and crizanlizumab are new drugs approved SCD, targeting different steps of the complex pathophysiological mechanism. Gene therapy represents an innovative and encouraging strategy currently under evaluation in several RA and recently approved for β‐thalassemia. Moreover, the advent of gene‐editing technologies represents an additional option, mainly focused on correcting the defective gene or editing the expression of genes that regulate fetal hemoglobin synthesis. In this review, we aim to update the status of innovative treatments and the ongoing trials and discuss RA treatments’ future directions. Interestingly, several molecules that showed promising results for treating one of these disorders are now under evaluation in the others. In the near future, the management of RA will probably consist of polypharmacotherapy tailored to patients’ characteristics.
Mammalian cells require iron to satisfy their metabolic needs and to accomplish specialized functions, such as hematopoiesis, mitochondrial biogenesis, energy metabolism, or oxygen transport. Iron ...homeostasis is balanced by the interplay of proteins responsible for iron import, storage, and export. A misbalance of iron homeostasis may cause either iron deficiencies or iron overload diseases. The clinical work-up of iron dysregulation is highly important, as severe symptoms and pathologies may arise. Treating iron overload or iron deficiency is important to avoid cellular damage and severe symptoms and improve patient outcomes. The impressive progress made in the past years in understanding mechanisms that maintain iron homeostasis has already changed clinical practice for treating iron-related diseases and is expected to improve patient management even further in the future.
The homeostasis of tissues in a chronic disease is an essential function of the alternative pathway (AP) of the complement system (CS). However, if not controlled, it may also be detrimental to ...healthy cells with a consequent aggravation of symptoms. The protoporphyria (PP) is a rare chronic disease that causes phototoxicity in visible light with local skin pain and general malaise. In order to establish if there is a systemic involvement of the CS during sun exposure, we designed a non-invasive method with a serum collection in winter and summer from 19 PP and 13 controls to detect the levels of CS protein: Properdin, Factor H (FH), and C5. Moreover, the global radiation data were collected from the regional agency of environmental protection (ARPA). The results show growing values for every protein in patients with PP, compared to control, in both seasons, in particular in summer compared to winter. To reinforce the evidence, we have estimated the personal exposure of patients based on the global radiation data. The main factors of the AP increased over the season, confirming the involvement of the AP in relation to light exposure. The systemic response could justify the general malaise of patients after long light exposure and can be exploited to elucidate new therapeutic approaches.
Luspatercept has recently been approved for the treatment of beta-thalassemia and its use in clinical practice has been increasing. As it is the first erythroid maturation drug available for this ...diagnosis, the expertise about its use is still limited. To address this point, and to promote awareness and guide the clinical use of luspatercept in beta-thalassemia, this paper was developed as a consensus by experts from the Italian Society of Thalassemia and Hemoglobinopathies (SITE). After a brief presentation of the core features of luspatercept, a comprehensive set of questions is addressed, covering relevant aspects for the practical management of this new therapeutic option.
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