[Advance of research on the role of BCL11A in the occurrence and treatment of ß-Thalassemia].

ß-Thalassemia is a single-gene disease caused by mutations in ß-globin and has a distinct geographical characteristics. Current treatment for patients with moderate to severe thalassemia has mainly relied on long-term blood transfusion and/or hematopoietic stem cell transplantation. B cell lymphoma/leukemia 11A (BCL11A) as a transcriptional repressor plays a vital role in monitoring γ/ß hemoglobin switching, maintaining the normal function of hematopoietic stem cells, and regulating erythrocyte differentiation and lymphocyte development. With the rapid progress in gene editing technology, the BCL11A as a therapeutic target for ß-thalassemia has shown promising results. This article has systematically summarized the regulatory mechanism and therapeutic potential of the BCL11A, with an aim to provide new ideas for the treatment of ß-thalassemia.

Fetal anemia causes placental and maternal cellular damage: a lesson from fetal hemoglobin Bart's disease.

INTRODUCTION: The studies about effect of fetal anemia on placental and maternal molecular changes have rarely been published. This study aimed to compare oxidative stress levels and mitochondrial function in the placenta and maternal peripheral blood mononuclear cell (PMBCs) between anemic fetuses (using fetal Hb Bart's disease as a study model) and non-anemic fetuses. METHODS: A cross-sectional study was conducted on pregnancies affected by Hb Bart's disease and non-anemic fetuses between 16 and 22 weeks of gestation. Placental tissue and maternal blood for PBMCs were collected after pregnancy termination for determination of oxidative stress and mitochondrial function. RESULTS: A total of 18 pregnancies affected by Hb Bart's disease and 12 non-anemic fetuses were enrolled. Placental thickness was significantly greater (p-value <0.001) in the affected pregnancies, whereas all Doppler indices of uteroplacental blood flow were comparable. Mitochondrial dysfunction was significantly increased (p-value <0.001) in the placenta of the affected fetuses. In the mothers of affected fetuses, there was an increase in mitochondrial oxidative stress levels with a significant increase in mitochondrial dysfunction in isolated PBMCs (p-value <0.001). DISCUSSION: In the presence of normal uteroplacental Doppler studies, fetal anemia can induce a significant increase in oxidative stress and mitochondrial dysfunction in the placentas and mothers. The findings support that the placenta can be a source of oxidative stress agents which are released into systemic circulation prior to development of maternal adverse outcomes, and may explain pathophysiology of subsequent preeclampsia in late gestation, as commonly seen in pregnancies affected by fetal Hb Bart's disease, if pregnancy is not terminated.

Revolutionising healing: Gene Editing's breakthrough against sickle cell disease.

Recent advancements in gene editing illuminate new potential therapeutic approaches for Sickle Cell Disease (SCD), a debilitating monogenic disorder caused by a point mutation in the ß-globin gene. Despite the availability of several FDA-approved medications for symptomatic relief, allogeneic hematopoietic stem cell transplantation (HSCT) remains the sole curative option, underscoring a persistent need for novel treatments. This review delves into the growing field of gene editing, particularly the extensive research focused on curing haemoglobinopathies like SCD. We examine the use of techniques such as CRISPR-Cas9 and homology-directed repair, base editing, and prime editing to either correct the pathogenic variant into a non-pathogenic or wild-type one or augment fetal haemoglobin (HbF) production. The article elucidates ways to optimize these tools for efficacious gene editing with minimal off-target effects and offers insights into their effective delivery into cells. Furthermore, we explore clinical trials involving alternative SCD treatment strategies, such as LentiGlobin therapy and autologous HSCT, distilling the current findings. This review consolidates vital information for the clinical translation of gene editing for SCD, providing strategic insights for investigators eager to further the development of gene editing for SCD.

Compound heterozygosity for Southeast Asian hereditary persistence of fetal hemoglobin and ß0-thalassemia results in thalassemia intermedia: Pedigree analysis and genetic research in a family from South China. A case report.

RATIONALE: Compound heterozygotes for deletional ß-thalassemia can be difficult to diagnose due to its diverse clinical presentations and no routine screenings. This can lead to disease progression and delay in treatment. PATIENT CONCERNS: We reported pedigree analysis and genetic research in a family with rare ß-thalassemia. DIAGNOSIS: Pedigree analysis and genetic research demonstrated that the patient was a compound heterozygote for ß-thalassemia CD17/Southeast Asian hereditary persistence of fetal hemoglobin deletion, inherited from the parents. Magnetic resonance imaging T2* examination revealed severe iron deposition in the liver. Echocardiography revealed endocardial cushion defect. INTERVENTIONS: The patient was treated with Deferasirox after receiving the final molecular genetic diagnosis. The initial once-daily dose of Deferasirox was 20 mg/kg/d. OUTCOMES: The patient discontinued the medication three months after the first visit. Two years later, the patient visited the Department of Hepatobiliary and Pancreatic Diseases. He was recommended to undergo splenectomy after surgical repair of the congenital heart disease. However, the patient refused surgical treatment because of the economic burden. LESSONS: We report that fetal hemoglobin is a sensitive indicator for screening large deletions of the ß-globin gene, which can be effectively confirmed by the multiplex ligation-dependent probe amplification assay. In non-transfusion-dependent thalassemia patients, iron status assessment should be regularly performed, and iron chelation treatment should be initiated early. This case will provide insights for the diagnosis of rare genotypes of ß-thalassemia and has important implications for genetic counseling.

Hydroxyurea Adherence for Personal Best in Sickle Cell Treatment (HABIT) efficacy trial: Community health worker support may increase hydroxyurea adherence of youth with sickle cell disease.

Despite disease-modifying effects of hydroxyurea on sickle cell disease (SCD), poor adherence among affected youth commonly impedes treatment impact. Following our prior feasibility trial, the "Hydroxyurea Adherence for Personal Best in Sickle Cell Treatment (HABIT)" multi-site randomized controlled efficacy trial aimed to increase hydroxyurea adherence for youth with SCD ages 10-18 years. Impaired adherence was identified primarily through flagging hydroxyurea-induced fetal hemoglobin (HbF) levels compared to prior highest treatment-related HbF. Eligible youth were enrolled as dyads with their primary caregivers for the 1-year trial. This novel semi-structured supportive, multidimensional dyad intervention led by community health workers (CHW), was augmented by daily tailored text message reminders, compared to standard care during a 6-month intervention phase, followed by a 6-month sustainability phase. Primary outcomes from the intervention phase were improved Month 6 HbF levels compared to enrollment and proportion of days covered (PDC) for hydroxyurea versus pre-trial year. The secondary outcome was sustainability of changes up to Month 12. The 2020-2021 peak coronavirus disease 2019 (COVID-19) pandemic disrupted enrollment and clinic-based procedures; CHW in-person visits shifted to virtual scheduled interactions. We enrolled 50 dyads, missing target enrollment. Compared to enrollment levels, both HbF level and PDC significantly - but not sustainably - improved within the intervention group (p = .03 and .01, respectively) with parallel increased mean corpuscular volume (MCV) (p = .05), but not within controls. No significant between-group differences were found at Months 6 or 12. These findings suggest that our community-based, multimodal support for youth-caregiver dyads had temporarily improved hydroxyurea usage. Durability of impact should be tested in a trial with longer duration of CHW-led and mobile health support.

Identification and characterization of CHD4-associated eRNA as a novel modulator of fetal hemoglobin levels in ß-thalassemia.

Fetal-to-adult hemoglobin switching is controlled by programmed silencing of γ-globin while the re-activation of fetal hemoglobin (HbF) is an effective strategy for ameliorating the clinical severity of ß-thalassemia and sickle cell disease. The identification of enhancer RNAs (eRNAs) related to the fetal (α2γ2) to adult hemoglobin (α2ß2) switching remains incomplete. In this study, the transcriptomes of GYPA+ cells from six ß-thalassemia patients with extreme HbF levels were sequenced to identify differences in patterns of noncoding RNA expression. It is interesting that an enhancer upstream of CHD4, an HbF-related core subunit of the NuRD complex, was differentially transcribed. We found a significantly positive correlation of eRNA-CHD4 enhancer-gene interaction using the public database of FANTOM5. Specifically, the eRNA-CHD4 expression was found to be significantly higher in both CD34+ HSPCs and HUDEP-2 than those in K562 cells which commonly expressed high level of HbF, suggesting a correlation between eRNA and HbF expression. Furthermore, prediction of transcription binding sites of cis-eQTLs and the CHD4 genomic region revealed a putative interaction site between rs73264846 and ZNF410, a known transcription factor regulating HbF expression. Moreover, in-vitro validation showed that the inhibition of eRNA could reduce the expression of HBG expression in HUDEP-2 cells. Taken together, the findings of this study demonstrate that a distal enhancer contributes to stage-specific silencing of γ-globin genes through direct modulation of CHD4 expression and provide insights into the epigenetic mechanisms of NuRD-mediated hemoglobin switching.

Development of pathophysiologically relevant models of sickle cell disease and ß-thalassemia for therapeutic studies.

Ex vivo cellular system that accurately replicates sickle cell disease and ß-thalassemia characteristics is a highly sought-after goal in the field of erythroid biology. In this study, we present the generation of erythroid progenitor lines with sickle cell disease and ß-thalassemia mutation using CRISPR/Cas9. The disease cellular models exhibit similar differentiation profiles, globin expression and proteome dynamics as patient-derived hematopoietic stem/progenitor cells. Additionally, these cellular models recapitulate pathological conditions associated with both the diseases. Hydroxyurea and pomalidomide treatment enhanced fetal hemoglobin levels. Notably, we introduce a therapeutic strategy for the above diseases by recapitulating the HPFH3 genotype, which reactivates fetal hemoglobin levels and rescues the disease phenotypes, thus making these lines a valuable platform for studying and developing new therapeutic strategies. Altogether, we demonstrate our disease cellular systems are physiologically relevant and could prove to be indispensable tools for disease modeling, drug screenings and cell and gene therapy-based applications.

Ginsenoside Rg1 promotes fetal hemoglobin production in vitro: A potential therapeutic avenue for ß-thalassemia.

ß-thalassemia, a globally prevalent genetic disorder, urgently requires innovative treatment options. Fetal hemoglobin (HbF) induction stands as a key therapeutic approach. This investigation focused on Ginsenoside Rg1 from the Panax genus for HbF induction. Employing K562 cells and human erythroid precursor cells (ErPCs) derived from neonatal cord blood, the study tested Rg1 at different concentrations. We measured its effects on γ-globin mRNA levels and HbF expression, alongside assessments of cell proliferation and differentiation. In K562 cells, Rg1 at 400 µM significantly increased γ-globin mRNA expression by 4.24 ± 1.08-fold compared to the control. In ErPCs, the 800 µM concentration was most effective, leading to an over 80% increase in F-cells and a marked upregulation in HbF expression. Notably, Rg1 did not adversely affect cell proliferation or differentiation, with the 200 µM concentration showing an increase in γ-globin mRNA by 2.33 ± 0.58-fold, and the 800 µM concentration enhancing HbF expression by 2.59 ± 0.03-fold in K562 cells. Our results underscore Rg1's potential as an effective and safer alternative for ß-thalassemia treatment. By significantly enhancing HbF levels without cytotoxicity, Rg1 offers a notable advantage over traditional treatments like Hydroxyurea. While promising, these in vitro findings warrant further in vivo exploration to confirm Rg1's therapeutic efficacy and to unravel its underlying mechanistic pathways.

Characterization of a cohort of Angolan children with sickle cell anemia treated with hydroxyurea.

BACKGROUND: Sickle Cell Anemia (SCA) is a monogenic disease, although its severity and response to treatment are very heterogeneous. OBJECTIVES: This study aims to characterize a cohort of Angolan children with SCA and evaluate their response to hydroxyurea (HU) treatment and the potential side effects and toxicity. METHODS: The study enrolled 215 patients between 3 and 12 years old before and after the administration of HU, at a fix dose of 20 mg/kg/day for 12 months. RESULTS: A total of 157 patients started HU medication and 141 of them completed the 12-month treatment. After initiating HU treatment, the frequency of clinical events decreased (transfusions 53.4 %, hospitalizations 47.1 %). The response to HU medication varied among patients, with some experiencing an increase in fetal hemoglobin (HbF) of <5 %. The mean increase in HbF was 11.9 %, ranging from 1.8 % to 31 %. Responders to HU treatment were 57 %, inadequate responders 38.7 % and non-adherent 4.2 %. No clinical side effects related to HU were reported. Hematological toxicities were transient and reversible. Children naïve to HU and with lower HbF reported higher number of hospitalizations caused by malaria infection. During HU treatment, the frequency of malaria episodes did not appear to be affected by HbF levels. CONCLUSIONS: the present study provided a valuable contribution to the understanding of the clinical and laboratory profiles of Angolan children with SCA. These findings support the evidence that the implementation of prophylactic measures and treatment with HU is associated with increased survival in children with SCA.

Quantitative Model-Based Assessment of Multiple Sickle Cell Disease Therapeutic Approaches Alone and in Combination.

Three sickle cell disease (SCD) treatment strategies, stabilizing oxygenated hemoglobin (oxyHb), lowering 2,3-BPG, and inducing fetal hemoglobin (HbF) expression aim to prevent red blood cell (RBC) sickling by reducing tense-state sickle hemoglobin that contributes to polymer formation. Induction of 30% HbF is seen as the gold standard because 30% endogenous expression is associated with a lack of symptoms. However, the level of intervention required to achieve equivalent polymerization protection by the other strategies is uncertain, and there is little understanding of how these approaches could work in combination. We sought to develop an oxygen saturation model that could assess polymerization protection of all three approaches alone or in combination by extending the Monod-Wymann-Changeux model to include additional mechanisms. Applying the model to monotherapies suggests 51% sickle hemoglobin (HbS) occupancy with an oxyHb stabilizer or lowering RBC 2,3 BPG concentrations to 1.8 mM would produce comparable polymerization protection as 30% HbF. The model predictions are consistent with observed clinical response to the oxyHb stabilizer voxelotor and the 2,3-BPG reducer etavopivat. The model also suggests combination therapy will have added benefit in the case of dose limitations, as is the case for voxelotor, which the model predicts could be combined with 20% HbF or 2,3-BPG reduction to 3.75 mM to reach equivalent protection as 30% HbF. The proposed model represents a unified framework that is useful in supporting decisions in preclinical and early clinical development and capable of evolving with clinical experience to gain new and increasingly confident insights into treatment strategies for SCD.

Misdiagnosis of ß-Thalassemia Major Due to Chinese Gγ+(Aγδß)0-Thalassemia Combined with ß0-Thalassemia.

δß-thalassemia is a rare type of thalassemia characterized by increased Hb F levels, including mainly Chinese Gγ(Aγδß)0-thalassemia, Yunnanese Gγ(Aγδß)0-thalassemia, Cantonese Gγ(Aγδß)0-thalassemia in China. Due to the low rate of δß-thalassemia carriers, there are few reports of δß-thalassemia combined with ß-thalassemia causing ß-thalassemia major. Herein, we described the combination of Chinese Gγ(Aγδß)0-thalassemia and ß-thalassemia leading to ß-thalassemia major in a Chinese patient. Hemoglobin analysis was performed by capillary electrophoresis (CE). Routine genetic analysis was carried out by gap-polymerase chain reaction (Gap-PCR) and PCR and reverse dot blot (PCR-RDB). Multiple ligation-dependent probe amplification (MLPA) was used to detect the large deletion, and Gap-PCR confirmed the deletion. A CE result showed an elevated Hb F level of 98.7% and 11.7% in the proband and her mother, but the proband was diagnosed with ßCD17M/ßCD17M using routine genetic analysis. However, her father was heterozygous for CD17 in ß-globin, and her mother was detected as SEA heterozygous. The further analysis presented that the proband had actually missed the diagnosis of Chinese Gγ(Aγδß)0-thalassemia by MLPA and PCR-RDB. Finally, the genotype of the proband was corrected from ßCD17M/ßCD17M to ßCD17M/ßGγ(Aγδß)0. This is the first report of Chinese Gγ(Aγδß)0-thalassemia combined with ß-thalassemia resulting in ß-thalassemia major in China. Screening for δß-thalassemia by Hb analysis could be an effective method.

Development of a new staining protocol for the Kleihauer-Betke test to facilitate the reading of difficult cases.

BACKGROUND: The Kleihauer-Betke (KB) test allows the detection of fetal red blood cells (containing fetal hemoglobin, HbF) in the maternal blood to identify and quantify potential fetal-maternal hemorrhages. In certain cases, detecting fetal red blood cells with conventional staining is difficult. False-positive results or overestimation of the quantity of fetal red blood cells may occur in cases of maternal hemoglobinopathy. In this study, we developed a new staining protocol to facilitate the reading of difficult smears and improve the precision of the quantification of fetal red blood cells; we also analyzed the performance of this new method. This study assessed blood samples with and without hemoglobin abnormalities, which present difficulties when interpreting the KB test. METHODS: The new staining formula is based on an improved elution technique and the use of a different stain instead of hematoxylin. To test this staining method, 16 samples from patients with abnormal hemoglobin electrophoresis and 14 samples from patients with normal hemoglobin electrophoresis were analyzed using the KB test with the classical staining method and the new staining method. In addition, a second series was prepared using the same samples spiked with fetal red blood cells from newborn blood, to compare the accuracy of the two methods in identifying fetal red blood cells. RESULTS: In the 60 slides analyzed with both staining methods, we found that the new technique improved the accuracy from 78 to 85%; lowered the coefficient of variation between the operators, which decreased from 20.7% to 12.7%; increased the specificity in our population from 56 to 70%; and decreased the number of false-positive cases by 30%. CONCLUSIONS: We successfully developed a new staining technique that facilitates the reading of difficult slides and improves the specificity of the detection of fetal red blood cells. This technique is recommended as a secondary method to use before sending the sample for additional exploration.

Base editing of key residues in the BCL11A-XL-specific zinc finger domains derepresses fetal globin expression.

BCL11A-XL directly binds and represses the fetal globin (HBG1/2) gene promoters, using 3 zinc-finger domains (ZnF4, ZnF5, and ZnF6), and is a potential target for ß-hemoglobinopathy treatments. Disrupting BCL11A-XL results in derepression of fetal globin and high HbF, but also affects hematopoietic stem and progenitor cell (HSPC) engraftment and erythroid maturation. Intriguingly, neurodevelopmental patients with ZnF domain mutations have elevated HbF with normal hematological parameters. Inspired by this natural phenomenon, we used both CRISPR-Cas9 and base editing at specific ZnF domains and assessed the impacts on HbF production and hematopoietic differentiation. Generating indels in the various ZnF domains by CRISPR-Cas9 prevented the binding of BCL11A-XL to its site in the HBG1/2 promoters and elevated the HbF levels but affected normal hematopoiesis. Far fewer side effects were observed with base editing- for instance, erythroid maturation in vitro was near normal. However, we observed a modest reduction in HSPC engraftment and a complete loss of B cell development in vivo, presumably because current base editing is not capable of precisely recapitulating the mutations found in patients with BCL11A-XL-associated neurodevelopment disorders. Overall, our results reveal that disrupting different ZnF domains has different effects. Disrupting ZnF4 elevated HbF levels significantly while leaving many other erythroid target genes unaffected, and interestingly, disrupting ZnF6 also elevated HbF levels, which was unexpected because this region does not directly interact with the HBG1/2 promoters. This first structure/function analysis of ZnF4-6 provides important insights into the domains of BCL11A-XL that are required to repress fetal globin expression and provide framework for exploring the introduction of natural mutations that may enable the derepression of single gene while leaving other functions unaffected.

Activation of γ-globin expression by LncRNA-mediated ERF promoter hypermethylation in ß-thalassemia.

The mechanism that drives the switch from fetal to adult hemoglobin (Hb) provides a therapeutic target for ß-thalassemia. We have previously identified that hypermethylation of transcription factor ERF promoter reactivated γ-globin expression. To uncover the mechanism underlying the hypermethylation of ERF promoter, we performed RNA sequencing in ß0/ß0-thalassemia patients and identified an upregulated long noncoding RNA (RP11-196G18.23) associated with HbF production. RP11-196G18.23 bound to the ERF promoter and recruited DNA methyltransferase 3A to promote DNA hypermethylation-mediated ERF downregulation, thereby ameliorating ERF-induced γ-globin inactivation. The identification of RP11-196G18.23 provides an epigenetic mechanism for the reactivation of fetal γ-globin expression for ß-hemoglobinopathies.

Exagamglogene Autotemcel: First Approval.

Exagamglogene autotemcel (Casgevy™) is a genetically modified autologous CD34+ cell enriched population. It contains human haematopoietic stem and progenitor cells edited ex vivo by CRISPR/Cas9 (a DNA double strand break-inducing nuclease system) to differentiate into erythroid cells that produce high levels of foetal hemoglobin. Developed by Vertex Pharmaceuticals and CRISPR Therapeutics, exagamglogene autotemcel received its first approval on 16 November 2023 in the UK for the treatment of transfusion-dependent ß-thalassemia (TDT) in patients aged ≥ 12 years for whom haematopoietic stem cell (HSC) transplantation is appropriate and a human leukocyte antigen matched related HSC donor is not available. On the same day, it was also approved in the UK for the treatment of sickle cell disease (SCD) in patients aged ≥ 12 years with recurrent vasoocclusive crises (VOCs) who have the ßS/ßS, ßS/ß+ or ßS/ß0 genotype for whom HSC transplantation is appropriate and a human leukocyte antigen matched related HSC donor is not available. Subsequently, exagamglogene autotemcel was approved in the USA on 8 December 2023 for the treatment of SCD in patients aged ≥ 12 years with recurrent VOCs and received a positive opinion in the EU on 14 December 2023 for the treatment of TDT and SCD. A regulatory assessment of exagamglogene autotemcel is currently underway for the treatment of TDT in the USA. This article summarizes the milestones in the development of exagamglogene autotemcel leading to these first approvals.

Hydroxyurea at escalated dose versus fixed low-dose hydroxyurea in adults with sickle cell disease.

Hydroxyurea reduces the frequency of vaso-occlusive complications, increases hemoglobin, and decreases mortality in sickle cell disease (SCD). Although current guidelines recommend escalation to maximum tolerated dose (MTD), the use of fixed low-dose hydroxyurea is common in low-resource countries. We conducted a systematic review and meta-analysis to evaluate the efficacy of escalated doses versus fixed low-dose of hydroxyurea in adults with SCD. Nine studies were included in the quantitative synthesis, four evaluating fixed low-dose and five evaluating escalated doses of hydroxyurea. Average daily doses of hydroxyurea in the fixed low-dose and escalated dose studies were ~10 and 22 mg/kg, respectively. There was no difference in the estimate of vaso-occlusive crisis rate between escalated and fixed low-dose studies (p = .73). The mean difference in hemoglobin from baseline to follow-up was greater for fixed low-dose than escalated dose studies (1.07 g/dL vs. 0.54 g/dL, p = .01). No difference was seen in the mean estimate of fetal hemoglobin. Despite limited eligible studies and substantial heterogeneity of effect between the studies for several outcomes, there appears to be clinical equipoise regarding the most appropriate hydroxyurea dosing regimen in adults with SCD. Controlled studies of hydroxyurea at MTD versus fixed low-dose in adults with SCD are required.

Inhibitory effects of SARS-CoV-2 spike protein and BNT162b2 vaccine on erythropoietin-induced globin gene expression in erythroid precursor cells from patients with ß-thalassemia.

During the recent coronavirus disease 2019 (COVID-19) pandemic several patients with ß-thalassemia have been infected by severe acute respiratory syndrome coronavirus (SARS-CoV-2), and most patients were vaccinated against SARS-CoV-2. Recent studies demonstrate an impact of SARS-CoV-2 infection on the hematopoietic system. The main objective of this study was to verify the effects of exposure of erythroid precursor cells (ErPCs) from patients with ß-thalassemia to SARS-CoV-2 spike protein (S-protein) and the BNT162b2 vaccine. Erythropoietin (EPO)-cultured ErPCs have been either untreated or treated with S-protein or BNT162b2 vaccine. The employed ErPCs were from a ß-thalassemia cellular Biobank developed before the COVID-19 pandemic. The genotypes were ß+-IVSI-110/ß+-IVSI-110 (one patient),  ß039/ß+-IVSI-110 (3 patients), and ß039/ ß039 (2 patients). After treatment with S-protein or BNT162b2 for 5 days, lysates were analyzed by high performance liquid chromatography (HPLC), for hemoglobin production, and isolated RNA was assayed by RT-qPCR, for detection of globin gene expression. The main conclusions of the results obtained are that SARS-CoV-2 S-protein and BNT162b2 vaccine (a) inhibit fetal hemoglobin (HbF) production by ß-thalassemic ErPCs and (b) inhibit γ-globin mRNA accumulation. In addition, we have performed in silico studies suggesting a high affinity of S-protein to HbF. Remarkably, the binding interaction energy of fetal hemoglobin to S-protein was comparable with that of angiotensin-converting enzyme 2 (ACE2). Our results are consistent with the hypothesis of a relevant impact of SARS-CoV-2 infection and COVID-19 vaccination on the hematopoietic system.

Impact of splenectomy on circulating microparticles in patients with sickle cell anemia.

INTRODUCTION: Circulating microparticles (MP) are being described as potential biomarkers for disease activity in a variety of conditions including sickle cell anemia (SCA). However, relatively little is known about the influence of spleen status on MP levels in patients with SCA. METHODS: Using a prospective study design we characterize circulating MP in 144 patients with SCA in steady state by assessing their cellular origin and their relationships to spleen status defined by clinical and imaging findings. In addition, MP levels were studied according to demographic characteristics, clinical status, treatment modalities, and other hematological and biochemical parameters. Absolute plasma concentrations of MP were determined by flow cytometry. RESULTS: Patients with SCA displayed a 10-fold increase in levels of MP derived from red blood cell (RBC) and platelets (PLT) when compared to their healthy counterparts (p < 0.0001). Splenectomized patients with SCA have more pronounced levels of MPRBC and MPPLT, and remained elevated after several weeks of follow-up. Levels of MP were not significantly associated with spleen removal procedures, age, gender, clinical severity score, hydroxyurea therapy, hemoglobin F, and co-existence of glucose-6-phosphate dehydrogenase deficiency. CONCLUSION: Collectively, these results suggest that splenectomy affects circulating levels of MP regardless of the known SCA modifiers and correlates.

Bach1 inhibitor HPP-D mediates γ-globin gene activation in sickle erythroid progenitors.

Sickle cell disease (SCD) is the most common ß-hemoglobinopathy caused by various mutations in the adult ß-globin gene resulting in sickle hemoglobin production, chronic hemolytic anemia, pain, and progressive organ damage. The best therapeutic strategies to manage the clinical symptoms of SCD is the induction of fetal hemoglobin (HbF) using chemical agents. At present, among the Food and Drug Administration-approved drugs to treat SCD, hydroxyurea is the only one proven to induce HbF protein synthesis, however, it is not effective in all people. Therefore, we evaluated the ability of the novel Bach1 inhibitor, HPP-D to induce HbF in KU812 cells and primary sickle erythroid progenitors. HPP-D increased HbF and decreased Bach1 protein levels in both cell types. Furthermore, chromatin immunoprecipitation assay showed reduced Bach1 and increased NRF2 binding to the γ-globin promoter antioxidant response elements. We also observed increased levels of the active histone marks H3K4Me1 and H3K4Me3 supporting an open chromatin configuration. In primary sickle erythroid progenitors, HPP-D increased γ-globin transcription and HbF positive cells and reduced sickled erythroid progenitors under hypoxia conditions. Collectively, our data demonstrate that HPP-D induces γ-globin gene transcription through Bach1 inhibition and enhanced NRF2 binding in the γ-globin promoter antioxidant response elements.