Β-thalassemic Mice Research Articles

A novel synthetic compound, deferiprone–resveratrol hybrid (DFP-RVT), promotes hepatoprotective effects and ameliorates iron-induced oxidative stress in iron-overloaded β-thalassemic mice

A high amount of iron in β-thalassemia patients can lead to oxidative stress and organ dysfunction, especially liver, the main iron accumulated organ. Iron catabolism causes the generation of reactive oxygen species (ROS), triggering liver inflammation, fibrosis, and cirrhosis. Deferiprone-resveratrol hybrid (DFP-RVT) is chemically synthesized by combining deferiprone (DFP) and resveratrol (RVT) which shows an iron-chelating property along with antioxidant activity. This study explored the hepatoprotective effect of DFP-RVT in iron overloaded β-knockout (BKO) thalassemic mice. The results revealed that DFP-RVT treatment improved liver function in iron-overloaded BKO mice by reducing liver enzymes and increasing hepcidin levels compared to iron overload control mice. Both DFP alone and DFP-RVT treatment groups demonstrated iron chelation effects by decreasing liver iron content (LIC), iron profiles, and iron deposition in the liver. Moreover, DFP-RVT powerfully showed antioxidant properties by decreasing liver and plasma thiobarbituric acid reactive substances (TBARs) and increasing reduced glutathione (GSH) and superoxide dismutase (SOD). Interestingly, transforming growth factor β1 (TGFβ1), which can contribute to chronic liver disease through liver injury, inflammation, fibrosis, and cirrhosis, is highly expressed in iron-overloaded mice. However, both DFP and DFP-RVT treatment significantly reduced TGFβ1 levels compared to the iron-overloaded group. Therefore, DFP-RVT could be a potent hepatoprotective compound through the mobilization of iron, reduction of ROS, improvement of liver enzymes, and alleviation of liver damage, potentially relieving liver dysfunction in iron-overloaded BKO mice.

Bone marrow Tfr2 deletion improves the therapeutic efficacy of the activin-receptor ligand trap RAP-536 in β-thalassemic mice.

β-thalassemia is a disorder characterized by anemia, ineffective erythropoiesis (IE), and iron overload, whose treatment still requires improvement. The activin receptor-ligand trap Luspatercept, a novel therapeutic option for β-thalassemia, stimulates erythroid differentiation inhibiting the transforming growth factor β pathway. However, its exact mechanism of action and the possible connection with erythropoietin (Epo), the erythropoiesis governing cytokine, remain to be clarified. Moreover, Luspatercept does not correct all the features of the disease, calling for the identification of strategies that enhance its efficacy. Transferrin receptor 2 (TFR2) regulates systemic iron homeostasis in the liver and modulates the response to Epo of erythroid cells, thus balancing red blood cells production with iron availability. Stimulating Epo signaling, hematopoietic Tfr2 deletion ameliorates anemia and IE in Hbbth3/+ thalassemic mice. To investigate whether hematopoietic Tfr2 inactivation improves the efficacy of Luspatercept, we treated Hbbth3/+ mice with or without hematopoietic Tfr2 (Tfr2BMKO/Hbbth3/+) with RAP-536, the murine analog of Luspatercept. As expected, both hematopoietic Tfr2 deletion and RAP-536 significantly ameliorate IE and anemia, and the combined approach has an additive effect. Since RAP-536 has comparable efficacy in both Hbbth3/+ and Tfr2BMKO/Hbbth3/+ animals, we propose that the drug promotes erythroid differentiation independently of TFR2 and EPO stimulation. Notably, the lack of Tfr2, but not RAP-536, can also attenuate iron-overload and related complications. Overall, our results shed further light on the mechanism of action of Luspatercept and suggest that strategies aimed at inhibiting hematopoietic TFR2 might improve the therapeutic efficacy of activin receptor-ligand traps.

A human anti-matriptase-2 antibody limits iron overload, α-globin aggregates, and splenomegaly in β-thalassemic mice

AbstractIron plays a major role in the deterioration of β-thalassemia. Indeed, the high levels of transferrin saturation and iron delivered to erythroid progenitors are associated with production of α-globin precipitates that negatively affect erythropoiesis. Matriptase-2/TMPRSS6, a membrane-bound serine protease expressed in hepatocytes, negatively modulates hepcidin production and thus is a key target to prevent iron overload in β-thalassemia. To address safety concerns raised by the suppression of Tmprss6 by antisense oligonucleotides or small interfering RNA, we tested a fully human anti-matriptase-2 antibody, RLYB331, which blocks the protease activity of matriptase-2. When administered weekly to Hbbth3/+ mice, RLYB331 induced hepcidin expression, reduced iron loading, prevented the formation of toxic α-chain/heme aggregates, reduced ros oxygen species formation, and improved reticulocytosis and splenomegaly. To increase the effectiveness of RLYB331 in β-thalassemia treatment even further, we administered RLYB331 in combination with RAP-536L, a ligand-trapping protein that contains the extracellular domain of activin receptor type IIB and alleviates anemia by promoting differentiation of late-stage erythroid precursors. RAP-536L alone did not prevent iron overload but significantly reduced apoptosis in the erythroid populations of the bone marrow, normalized red blood cell counts, and improved hemoglobin and hematocrit levels. Interestingly, the association of RLYB331 with RAP-536L entirely reversed the β-thalassemia phenotype in Hbbth3/+ mice and simultaneously corrected iron overload, ineffective erythropoiesis, splenomegaly, and hematological parameters, suggesting that a multifunctional molecule consisting of the fusion of RLYB331 with luspatercept (human version of RAP-536L) would allow administration of a single medication addressing simultaneously the different pathophysiological aspects of β-thalassemia.

Lactate administration improves laboratory parameters in murine models of iron overload

AbstractCurrent iron overload therapeutics have inherent drawbacks including perpetuated low hepcidin. Here, we unveiled that lactate, a potent hepcidin agonist, effectively reduced serum and hepatic iron levels in mouse models of iron overload with an improved erythropoiesis in β-thalassemic mice.

Expression of microRNA-155 in thalassemic erythropoiesis.

Ineffective erythropoiesis (IE) is the primary cause of anemia and associated pathologies in β-thalassemia. The characterization of IE is imbalance of erythroid proliferation and differentiation, resulting in increased erythroblast proliferation that fails to differentiate and gives rise to enucleate RBCs. MicroRNAs (miRs) are known to play important roles in hematopoiesis. miR-155 is a multifunctional molecule involved in both normal and pathological hematopoiesis, and its upregulation is observed in patients with β-thalassemia/HbE. However, the expression and function of miR-155, especially in β-thalassemia, have not yet been explored. To study miR-155 expression in thalassemia, erythroblast subpopulations, CD45-CD71+Ter-119+ and CD45-CD71-Ter-119+ were collected from β IVSII-654 thalassemic bone marrow. Additionally, a two-phase culture of mouse bone marrow erythroid progenitor cells was performed. Expression of miR-155 and predicted mRNA target genes, c-myc, bach-1 and pu-1, were determined by quantitative reverse transcription (qRT)-polymerase chain reaction (PCR) and normalized to small nucleolar RNA (snoRNA) 202 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), respectively. To investigate the effect of miR-155 expression, erythroblasts were transfected with miR-inhibitor and -mimic in order to elevate and eliminate miR-155 expression, respectively. Erythroid cell differentiation was evaluated by Wright-Giemsa staining and flow cytometry. miR-155 was upregulated, both in vivo and in vitro, during erythropoiesis in β-thalassemic mice. Our study revealed that gain- and loss of function of miR-155 were involved in erythroid proliferation and differentiation, and augmented proliferation and differentiation of thalassemic mouse erythroblasts may be associated with miR-155 upregulation. miR-155 upregulation in β-thalassemic mice significantly increased the percentage of basophilic and polychromatic erythroblasts. Conversely, a significant decrease in percentage of basophilic and polychromatic erythroblasts was observed in β-thalassemic mice transfected with anti-miR-155 inhibitor. We also examined the mRNA targets (c-myc, bach-1 and pu-1) of miR-155, which indicated that c-myc is a valid target gene of miR-155 that regulates erythroid differentiation. miR-155 regulates IE in β-thalassemia via c-myc expression controlling erythroblast proliferation and differentiation.

Iron Restriction Alleviates β-Thalassemia By Stimulating ULK1-Mediated Autophagy of Free α-Globin

In β-thalassemia, mutations in the HBB gene cause reduced β-globin synthesis with accumulation of toxic free α-globin, leading to ineffective erythropoiesis and hemolysis. We showed previously that β-thalassemic erythroblasts can eliminate free α-globin by ULK1-mediated autophagy and that this process is stimulated by rapamycin inhibition of mTORC1, which phosphorylates ULK1 to inhibit its activity. Several studies have shown that iron restriction can reduce the accumulation of free α-globin precipitates to alleviate the pathophysiology of β-thalassemia. Considering that iron stimulates mTORC1 activity in numerous cell types including erythroblasts, we tested the hypothesis that iron restriction alleviates β-thalassemia by inhibiting mTORC1, thereby stimulating ULK1-mediated autophagy of free α-globin. Hbb Th3/+ β-thalassemic mice or HbbTh3/+Ulk1-/- mice were treated with the clinical stage oral ferroportin inhibitor vamifeport (known also as VIT-2763) for 45 days to cause systemic iron restriction. In HbbTh3/+ mice, vamifeport administration led to 66% and 40% reductions in the levels of serum iron (p<0.001) and ferritin (p=0.001), respectively, as expected. Iron restriction by vamifeport alleviated the pathophysiology of β-thalassemia compared to vehicle-treatment in HbbTh3/+, as evidenced by a 21% increase in RBC count (p<0.001), 32% reduction in insoluble α-globin in red blood cells (RBC) (p=0.002), 41% reduction in reticulocyte count (p<0.001), 27% reduction in spleen mass (p=0.034) and enhanced maturation of spleen and bone marrow erythroid precursors, indicating reduced ineffective erythropoiesis. Multivariate analysis showed that beneficial effects of iron restriction in β-thalassemic mice were attenuated by concomitant disruption of both Ulk1 alleles. For example, vamifeport treatment of HbbTh3/+Ulk1-/- mice caused only a 12% increase in RBC counts (p=0.015 compared to HbbTh3/+). Additionally, iron restriction improved erythroid maturation in HbbTh3/+Ulk1-/- mice, but to a significantly lesser extent than in thalassemic mice with intact Ulk1alleles. We obtained similar results by inducing iron deprivation with PR73, a peptide hepcidin mimetic. Mechanistically, long-term administration of vamifeport was associated with inhibition of mTORC1, as evidenced by 32% reductions in the phosphorylation of its substrate, ribosomal protein S6 kinase (p=0.004), and activation of the heme-regulated eIF2α kinase (HRI), indicated by increased phosphorylation of eIF2α and/or accumulation of the HRI effector transcription factor ATF4. Similar results were obtained with PR73. Administration of a single dose of PR73 to HbbTh3/+ mice led to activation of HRI in Ter119 + erythroblasts after 8 hours, which preceded the downregulation of mTORC1 activity, detected at 24 hours. This is consistent with prior studies showing that HRI inhibits mTORC1. Loss of ULK1 had no effect on suppression of mTORC1 with either drug, consistent with ULK1 being the substrate of mTORC1; we are currently investigating whether loss of ULK1 alters the HRI pathway. Together, our data support a mechanism through which iron restriction alleviates the pathophysiology of β-thalassemia in part by stimulating ULK1-mediated autophagy of free α-globin. This process is likely mediated by iron restriction that activates HRI which in turn inhibits mTORC1 to block its negative effects on ULK1. Additional mechanisms for iron regulation of mTORC1 activity are also possible. Our findings provide new insight into the mechanisms by which iron restriction alleviates β-thalassemia and illustrate how metabolic regulators of erythropoiesis impact the severity of β-thalassemia by eliminating free α-globin through a key protein quality control pathway.

Bone Marrow Sinusoidal Endothelial Cells Are a Site of Fgf23 Upregulation in Murine ß-Thalassemia

Fibroblast growth factor-23 (FGF23) is a bone-derived hormonal regulator of mineral metabolism with emerging functions in the bone marrow. FGF23 has been reported to negatively regulate erythropoiesis [PMID:24509850] and promote hematopoietic progenitor mobilization from the bone marrow [PMID:33512467]. Elevated FGF23 levels in the circulation have been described in iron-deficient subjects and also in subjects with the iron-loading anemia β-thalassemia. Recently, we reported bone marrow sinusoidal endothelial cells (BM-SEC) as a novel site of Fgf23 upregulation in mice with chronic iron-deficiency anemia and acute, phlebotomy-induced anemia [PMID:37417950]. We and others have detected Fgf23 mRNA elevation in total bone marrow of Hbb th3/+ mice, a model of non-transfusion dependent β-thalassemia that exhibits systemic iron loading. In the present study, we sought to clarify sites of Fgf23 promoter activity in Hbb th3/+ bone marrow using a reporter allele in which the enhanced green fluorescent protein (eGFP) coding sequence is knocked into the endogenous Fgf23 locus ( Fgf23 eGFP). We generated Hbb +/+ and Hbb th3/+ female littermates that carried either one ( Fgf23 +/eGFP) or zero ( Fgf23 +/+) copies of the Fgf23 reporter allele, which were raised on a standard rodent diet (200 mg/kg iron, 1.0% calcium, 0.7% phosphorus). Fgf23 eGFP/eGFP homozygotes were not generated due to known early growth retardation and mortality in Fgf23 null mice. After blood and tissue collection at 8 weeks of age, phenotypes of the 4 Hbb-Fgf23 genotype combinations were compared by two-way ANOVA. Compared to mice with intact Hbb and Fgf23 alleles ( Hbb +/+ Fgf23 +/+), Hbb th3/+ Fgf23 +/+ mice showed markedly elevated plasma levels of “total” FGF23 (sum of intact, active hormone and C-terminal cleaved fragments). Plasma total FGF23 levels in Hbb th3/+ Fgf23 +/+ and Hbb th3/+ Fgf23 +/eGFP mice were similar, indicating utility of the latter genotype for interrogating sites of increased Fgf23 expression in murine b-thalassemia. We therefore used anti-GFP immunohistochemistry in formalin-fixed bone marrow sections to assess Fgf23 eGFP reporter allele expression in the context of tissue architecture. Hbb th3/+ Fgf23 +/eGFP mice showed GFP expression in BM-SEC throughout the bone marrow, which was more intense than in non-anemic Hbb +/+ Fgf23 +/eGFP mice; controls lacking the Fgf23 eGFP allele confirmed anti-GFP antibody specificity. Hbb th3/+ mice also showed Fgf23 eGFP reporter expression in the thymic vasculature but not vasculature of the liver, spleen, or kidney. In contrast to their marked elevation in plasma total FGF23, Hbb th3/+ Fgf23 +/+ mice showed plasma levels of the intact, biologically-active FGF23 hormone that overlapped with levels in Hbb +/+ Fgf23 +/+ controls. Interestingly, compared with Hbb th3/+ Fgf23 +/+ mice, Hbb th3/+ Fgf23 +/eGFP mice showed 45% lower plasma intact FGF23, suggesting an effect of Fgf23 gene dosage. Given prior reported effects of FGF23 on hematopoiesis, we assessed if Fgf23 gene dosage modulated the severity of ineffective erythropoiesis in Hbb th3/+ mice. Compared to Hbb +/+ Fgf23 +/+ controls, Hbb th3/+ Fgf23 +/+ mice showed reductions in RBC, hemoglobin, and mean corpuscular hemoglobin, as well as increases in RDW and in spleen weight (reflecting extramedullary hematopoiesis). However, the severity of these parameters was not modified by heterozygous Fgf23 disruption ( Hbb th3/+ Fgf23 +/eGFP).While FGF23 has been reported to induce left ventricular hypertrophy [PMID:21985788], Hbb th3/+ Fgf23 +/+ and Hbb th3/+ Fgf23 +/eGFP mice showed similarly increased heart-to-body weight ratios compared to Hbb +/+ Fgf23 +/+ controls. In non-thalassemic mice, heterozygous Fgf23 disruption ( Hbb +/+ Fgf23 +/eGFP) caused a trend ( P=0.10) towards lower plasma intact FGF23 while not impacting hematological parameters or spleen weight. In summary, by showing that Fgf23 gene dosage modulates plasma intact FGF23 levels in Hbb th3/+ mice without altering severity of anemia or splenomegaly, our data suggest that moderate reductions in circulating levels of the intact FGF23 hormone do not alter the severity of ineffective erythropoiesis in Hbb th3/+mice at 8 weeks of age. Our finding that β-thalassemic mice exhibit Fgf23 upregulation in BM-SEC lays the groundwork for future investigation of the functional effects of locally-produced FGF23 in the thalassemic hematopoietic stem cell niche.

Metabolic and Proteomic Divergence Is Present in Circulating Monocytes and Tissue-Resident Macrophages from Berkeley Sickle Cell Anemia and β-Thalassemia Mice.

Sickle cell disease and β-thalassemia represent hemoglobinopathies arising from dysfunctional or underproduced β-globin chains, respectively. In both diseases, red blood cell injury and anemia are the impetus for end organ injury. Because persistent erythrophagocytosis is a hallmark of these genetic maladies, it is critical to understand how macrophage phenotype polarizations in tissue compartments can inform on disease progression. Murine models of sickle cell disease and β-thalassemia allow for a basic understanding of the mechanisms and provide for translation to human disease. A multi-omics approach to understanding the macrophage metabolism and protein changes in two murine models of β-globinopathy was performed on peripheral blood mononuclear cells as well as spleen and liver macrophages isolated from Berkley sickle cell disease (Berk-ss) and heterozygous B1/B2 globin gene deletion (Hbbth3/+) mice. The results from these experiments revealed that the metabolome and proteome of macrophages are polarized to a distinct phenotype in Berk-ss and Hbbth3/+ compared with each other and their common-background mice (C57BL6/J). Further, spleen and liver macrophages revealed distinct disease-specific phenotypes, suggesting that macrophages become differentially polarized and reprogrammed within tissue compartments. We conclude that tissue recruitment, polarization, and metabolic and proteomic reprogramming of macrophages in Berk-ss and Hbbth3/+ mice may be relevant to disease progression in other tissue.

Reducing erythroblast apoptosis in β-thalassemia via unfolded protein response (UPR) signaling

Apoptosis plays an important role in ineffective erythropoiesis in β-thalassemia. This early destruction causes severe anemia and contributes significantly to patient mortality. There are several treatment options for this disorder based on the use of drugs that inhibit the destruction of immature erythrocytes in the bone marrow. However, the clinical effectiveness of these drugs has yet to be proven. Therefore, new targets for more effective treatments are needed. The unfolded protein response (UPR) is a biological process that occurs in response to endoplasmic reticulum (ER) stress. To cope with ER stress, unfolded or misfolded proteins activate the UPR pathway, thereby activating a series of cell death pathways. Here, we propose that prolonged ER stress causes apoptosis via UPR signaling during erythroid development in β-thalassemia. Our proposed hypothesis is supported by 1) the involvement of UPR signaling in apoptotic cell death, 2) changes in UPR-related proteins in β-thalassemia, and 3) the availability of UPR signaling inhibitors. In vitro and in vivo studies should be conducted to identify the proteins that participate in the UPR pathway and identify molecular targets for therapy. The β-thalassemia mouse model could be used to evaluate the efficacy of UPR mimic drugs prior to clinical trials. If verified, gaining control over cell fate determination during UPR signaling in β-thalassemia may minimize erythroblast destruction.

Depletion of miR-144/451 alleviates anemia in β-thalassemic mice

Depletion of miR-144/451 alleviates anemia in β-thalassemic mice

Single-cell profiling of ineffective erythropoiesis in a mouse model of β-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/+ β-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 β-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 β-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.

Mitapivat, a pyruvate kinase activator, improves transfusion burden and reduces iron overload in β-thalassemic mice.

Not available.

BACH1 regulates erythrophagocytosis and iron-recycling in β-thalassemia.

Macrophages play essential roles in erythrophagocytosis and iron recycling. β-thalassemia is characterized by a genetic defect in hemoglobin synthesis, which increases the rate of iron recycling. We previously showed that reduced expression of the BTB and CNC homolog 1 (BACH1) gene leads to increased phagocytosis of abnormal RBCs by activated monocytes. However, the mechanisms underlying this abnormal RBC clearance remained unclear. Herein, the spleen and bone marrow cells of β-thalassemic mice were examined for erythrophagocytosis CD markers and iron-recycling genes. Higher expression levels of CD47 and CD163 on RBCs and macrophages, respectively, were observed in β-thalassemic mice than in wild-type cells. The decreased expression of BACH1 caused an increase in Nrf2, Spic, Slc40a1, and HMOX1 expression in splenic red pulp macrophages of thalassemic mice. To investigate BACH1 regulation, a macrophage cell line was transfected with BACH1-siRNA. Decreased BACH1 expression caused an increase in CD163 expression; however, the expression levels were lower when the cells were cultured in media supplemented with β-thalassemia/HbE patient plasma. Additionally, the iron recycling-related genes SPIC, SLC40A1, and HMOX1 were significantly upregulated in BACH1-suppressed macrophages. Our findings provide insights into BACH1 regulation, which plays an important role in erythrophagocytosis and iron recycling in thalassemic macrophages.

Effects of green tea extract treatment on erythropoiesis and iron parameters in iron-overloaded β-thalassemic mice.

β-Thalassemia is characterized by ineffective erythropoiesis leading to chronic anemia. Thus, increased iron absorption from the duodenum and via blood transfusions is required to maintain normal blood hemoglobin (Hb) levels and iron chelators in the removal of excessive iron. Certain agents are also needed for the improvement of stress erythropoiesis and iron dysregulation. Green tea extract (GTE), which is rich in epigallocatechin-3-gallate (EGCG), is known to possess radical scavenging and iron-chelating activities. We aimed to assess the effects of green tea extract on erythroid regulators, iron mobilization and anti-lipid peroxidation in the liver, spleen, and kidneys of iron-loaded β-globin gene knockout thalassemic (BKO) mice. Our results indicate that treatments of green tea extract and/or deferiprone (DFP) diminished levels of plasma erythropoietin (EPO) and erythroferrone (ERFE), and consistently suppressed kidney Epo and spleen Erfe mRNA expressions (p < .05) in iron- loaded BKO mice when compared with untreated mice. Coincidently, the treatments decreased plasma ferritin (Ft) levels, iron content levels in the liver (p < .05), spleen (p < .05), and kidney tissues of iron-loaded BKO mice. Furthermore, lipid-peroxidation products in the tissues and plasma were also decreased when compared with untreated mice. This is the first evidence of the orchestral role of green tea extract abundant with epigallocatechin-3-gallate in improving ineffective erythropoiesis, iron dysregulation and oxidative stress in iron-overloaded β-thalassemic mice.

Expression Levels of MiR-451 in Erythroid Differentiation and Its Correlation with Hematological Diseases

To investigate the expression of miR-451 during erythroid differentiation and its correlation with hematological diseases. The expression of miR-451 in erythroid differentiation of mouse hematopoietic stem cells (derived from fetal liver) was analyzed by cell culture, flow cytometry, magnetic bead sorting and qRT-PCR. The expression of miR-451 during erythroid differentiation of mouse erythroid leukemia cells (MEL) was analyzed by cell culture and qRT-PCR. The expression of miR-451 in peripheral blood of mice was detected by qRT-PCR, and the expression of miR-451 in fetal liver (14.5 days) was analyzed by microarray. The nucleated erythroid cells from bone marrow of wild type (WT) mice and β-thalassemia (β-thal) mice were sorted by flow cytometry, and the levels of miR-451 and erythroid genes were detected by qRT-PCR. The expression of miR-451 in peripheral blood of patients with clinical hematological diseases was detected by qRT-PCR. During the differentiation of mouse hematopoietic stem cells (derived from fetal liver) and MEL cells, the expression levels of miR-451 increased gradually. Compared with WT mice, the expression levels of miR-451 in peripheral blood, 14.5-day fetal liver cells and nucleated erythroid cells (sorted from bone marrow) of β-thal mice were significantly increased(P<0.05). Many erythroid differentiation genes in nucleated erythroid cells (sorted from bone marrow) of β-thal mice decreased. Compared with healthy controls, the expression levels of miR-451 was increased in peripheral blood of patients with β-thalassemia and iron deficiency anemia, while the expression levels of miR-451 was decreased in patients with aplastic anemia and myelodysplastic syndrome. During erythroid differentiation, the expression levels of miR-451 increases gradually. In hematological diseases, the expression levels of miR-451 is different from that of normal controls, which is expected to become an auxiliary diagnostic index for clinical hematological diseases.

Bone Marrow Tfr2 Deletion Modulates Systemic Metabolism in β-Thalassemic Mice to Sustain Augmented Erythropoiesis

Bone Marrow Tfr2 Deletion Modulates Systemic Metabolism in β-Thalassemic Mice to Sustain Augmented Erythropoiesis

Increased autophagy leads to decreased apoptosis during β-thalassaemic mouse and patient erythropoiesis

β-Thalassaemia results from defects in β-globin chain production, leading to ineffective erythropoiesis and subsequently to severe anaemia and other complications. Apoptosis and autophagy are the main pathways that regulate the balance between cell survival and cell death in response to diverse cellular stresses. Herein, the death of erythroid lineage cells in the bone marrow from both βIVS2-654-thalassaemic mice and β-thalassaemia/HbE patients was investigated. Phosphatidylserine (PS)-bearing basophilic erythroblasts and polychromatophilic erythroblasts were significantly increased in β-thalassaemia as compared to controls. However, the activation of caspase 8, caspase 9 and caspase 3 was minimal and not different from control in both murine and human thalassaemic erythroblasts. Interestingly, bone marrow erythroblasts from both β-thalassaemic mice and β-thalassaemia/HbE patients had significantly increased autophagy as shown by increased autophagosomes and increased co-localization between LC3 and LAMP-1. Inhibition of autophagy by chloroquine caused significantly increased erythroblast apoptosis. We have demonstrated increased autophagy which led to minimal apoptosis in β-thalassaemic erythroblasts. However, increased PS exposure occurring through other mechanisms in thalassaemic erythroblasts might cause rapid phagocytic removal by macrophages and consequently ineffective erythropoiesis in β-thalassaemia.

Apohemoglobin-haptoglobin complex alleviates iron toxicity in mice with β-thalassemia via scavenging of cell-free hemoglobin and heme

β-thalassemia is a genetic hemoglobin (Hb) disorder that affects millions of people world-wide. It is characterized by ineffective erythropoiesis and anemia. The resultant chronic anemia can require life-long blood transfusion regimens, leading to secondary hemochromatosis. Moreover, the abnormal red blood cells (RBCs) from β-thalassemia patients are prone to hemolytic events that release cell-free Hb and heme causing a series of events that result in oxidative organ and tissue damage. In this study, β-thalassemic mice were treated with a protein scavenger for six weeks, apohemoglobin-haptoglobin (apoHb-Hp), this protein scavenges cell free Hb and heme. We hypothesize that scavenging cell-free Hb and heme will lead to a positive therapeutic event. After the apoHb-hp treatment it was observed to reduce the weight of the liver and spleen and show an improvement in liver function by a drop in ALT, AST, and ALP markers. ApoHb-hp treatment also hints at an improved RBC half-life as the number of reticulocytes decreased, the mean corpuscular volume (MCV) increased, mean corpuscular hemoglobin increase and the RBC distribution width decreased. Furthermore, apoHb-Hp treatment reduced circulating serum iron concentration and transferrin saturation concentration. Based on these outcomes, introducing a scavenger protein can benefit β-thalassemic mice. This study demonstrated that apoHb-Hp treatment may be a viable strategy to mitigate toxicities associated with cell free Hb and heme, a driver of β-thalassemic issues.

The effect of cryopreservation media on the quality of β-thalassemia mouse spermatozoa.

The mouse model of human diseases is commonly used for biomedical study, including β-thalassemia (β-thal), an inherited hemoglobin disorder. Maintaining the mice strain by natural mating systems is costly and seems impractical, especially during the COVID-19 pandemic. Sperm-freezing is a cost-effective solution for β-thal mouse colony management. To determine appropriate cryopreservation media for β-thal mouse spermatozoa to establish a β-thal mouse sperm bank. The epididymal spermatozoa of C57BL/6 wild-type (WT) and β-globin gene knockout thalassemia (BKO) mice were frozen in four freezing media: I) raffinose-skim milk-monothioglycerol (MTG), II) raffinose-skim milk-glutamine, III) raffinose-egg yolk-glycerol, and IV) egg yolk-TES-Tris. The sperm quality was assessed prior to and following freeze-thawing. Compared with WT counterparts, the viable spermatozoa before freezing exhibiting elevated levels of oxidative stress were significantly greater in BKO (p = 0.01). After thawing, the membrane integrity of BKO spermatozoa preserved in I was significantly lower (p = 0.001). The sperm viability and membrane integrity of BKO males were also inferior when media III and IV were used (p = 0.008-0.027). The amount of oxidative stress in the spermatozoon of BKO mice was significantly greater when preserved in I, III, and IV (p = 0.002-0.044). Comparing freezing media, the motility and acrosome integrity of WT and BKO spermatozoa preserved in IV were significantly higher than those in other media (p < 0.001 to p = 0.01). Spermatozoa with the highest mitochondrial membrane potential were observed in I in both genotypes (p = 0.012 to p > 0.05). The viability, membrane integrity, and oxidative stress of post-thaw BKO spermatozoa did not significantly differ among freezing solutions. Irrespective of freezing media, spermatozoa of BKO males are rather more sensitive to cryopreservation than those of WT. Raffinose-skim milk-MTG/glutamine, raffinose-egg yolk-glycerol, and egg yolk-TES-Tris can all be used to preserve BKO mouse spermatozoa. However, with slightly better sperm characteristics, egg yolk-TES-Tris may be a diluent of choice for BKO mouse sperm cryopreservation. The addition of a reducing agent to thawing media is also strongly recommended to efficiently prevent oxidative stress and therefore improve frozen-thawed sperm survival.

Cell erythroid maturation approach: a new paradigm in the road map towards a cure for β-thalassaemia syndromes.

Cell erythroid maturation approach: a new paradigm in the road map towards a cure for β-thalassaemia syndromes.