Erythropoiesis ; physiology ; Humans ; Mitochondria ; physiology ; Mitochondrial Degradation

Macrophages have two major roles in regulating the dynamic equilibrium in erythropoiesis, promoting the differentiation and maturation of nucleated red blood cells into reticulocytes and removing old red blood cells. A recent mouse study has demonstrated that the phenotype of macrophages in erythroblastic islands is CD169+ VCAM-1+ ER-HR3+ CD11b+ F4/80+ Ly-6G+. Molecular connections between erythroid progenitor cells and central macrophages help to maintain the function and integrity of erythroblastic islands. New research advances in Kruppel-like factor 1 (KLF1) provide new evidence for the important role of macrophages in erythroblastic islands. Macrophages play an important role in erythropoiesis both in sickness and in health, and provide a potential targeted therapy for diseases such as polycythemia vera and beta-thalassemia in the future.
Animals ; Erythropoiesis ; Humans ; Integrin alpha4beta1 ; physiology ; Kruppel-Like Transcription Factors ; physiology ; Macrophages ; physiology ; Mice ; Phenotype ; Vascular Cell Adhesion Molecule-1 ; physiology

Evaluation of the mechanism of anemia in cancer patients might help to select patients for the more efficient use of erythropoietin (EPO, a growth factor for erythroid precursor cells). For this, we investigated whether the production of EPO responds to anemia and the bone marrow responds to EPO appropriately, and whether chronic inflammation is inhibitory to erythropoiesis in anemic cancer children. Serum levels of EPO, soluble transferrin receptor (sTfR), tumor necrosis factor (TNF)-alpha, and erythrocyte sedimentation rate (ESR) in anemic cancer children were measured by enzyme-linked immunosorbent assay and then the correlation coefficients between those parameters and hemoglobin (Hb) were determined. Both in leukemia and in solid tumor patients, there were significant inverse correlations between Hb and EPO (leukemia: tau=-0.547, p<0.0001; solid tumor: tau=-0.591, p<0.0001), and between sTfR and EPO (leukemia: tau=-0.223, p<0.05; solid tumor: tau=-0.401, p<0.05). In contrast, sTfR showed a correlation with Hb in leukemia (tau=0.216, p<0.05) but not in solid tumor patients. sTfR was suppressed in 53% of anemic episodes of leukemia and 78% of those of solid tumor patients. Our results suggest that in cancer children, the EPO production is not defective and chronic inflammation is not inhibitory to erythropoiesis. Rather, the defective erythropoiesis itself is thought to be responsible for the anemia.
Anemia/etiology/*physiopathology ; Blood Sedimentation ; Bone Marrow/physiology ; Child ; Erythropoiesis/*physiology ; Erythropoietin/blood ; Female ; Humans ; Male ; Neoplasms/complications/*physiopathology ; Receptors, Transferrin/blood ; Solubility ; Tumor Necrosis Factor-alpha/metabolism

BACKGROUNDPolycythemia vera (PV) is a malignant disorder of hemaopoietic stem cells which is characterized by clonal hyperproliferation and a low rate of apoptosis. This study was to assess endogenous erythroid colony (EEC) formation in the bone marrow of PV patients and determine its clinical significance.

METHODSThe bone marrow mononuclear cells of 26 patients with PV, 2 patients with secondary erythrocytosis (SE), and 19 normal controls were cultured by Marsh's method for EEC evaluation, and the clinical significance was evaluated.

RESULTSEECs appeared in 25 patients with PV but not in 2 patients with SE and 19 normal controls. The number of EECs and the EEC ratio [EEC/erythropoietin (EPO)-dependent colony forming unit-erythroid (CFU-E)] in PV patients positively correlated with hemoglobin (Hb) levels. Their EEC number did not correlate with white blood cell (WBC) counts, platelet (PLT) counts, or leukocyte alkaline phosphatase (LAP) scores. Their EEC did not correlate with serum EPO levels. Fifteen patients with PV were treated with hydroxyurea (Hu) and/or interferon-alpha (IFN-alpha). Their EEC ratio before treatment positively correlated with the treatment time required for complete remission (CR) and negatively correlated with the time before relapse. The EEC numbers of 7 PV patients treated with Hu/IFN-alpha decreased after the blood cell counts dropped to normal levels. There was a positive correlation between the EEC ratio and the incidence of attacks of vascular thrombosis in PV patients. The numbers of apoptosised bone marrow mononuclear cells in PV patients were lower than those in normal controls. The EEC numbers of PV patients negatively correlated with the rate of apoptosis of bone marrow mononuclear cells.

CONCLUSIONSEEC formation is characteristic in PV patients. EEC number in PV patients positively correlates with Hb levels, the time required for CR, and the incidence of attacks of vascular thrombosis. EEC number negatively correlates with the time before relapse. Bone marrow suppressive treatment might decrease EEC number. Thus, EEC number is a sensitive and specific parameter reflecting the abnormal hematopoietic clone burden induced by polycythemia vera. EEC number is an important diagnostic parameter for PV patients.

Adult ; Aged ; Apoptosis ; Colony-Forming Units Assay ; Erythroid Precursor Cells ; physiology ; Erythropoiesis ; Erythropoietin ; blood ; Female ; Humans ; Male ; Middle Aged ; Polycythemia Vera ; blood ; therapy ; Thrombosis ; epidemiology

In men, testosterone (T) deficiency is associated with decreased physical performance, as defined by adverse traits in body composition, namely increased body fat content and reduced muscle mass. Physical abilities in androgen-deficient men are further attenuated by lower oxygen supply due to decreased hemoglobin concentrations and by poor glucose utilization. Dysthymia and a lack of necessary aggressiveness also contribute to deteriorate physical effectiveness. Substitution of T can improve lipid and insulin metabolism as well as growth of muscle fibers and decreasing fat depots, which consequently will result in changes of body composition. Increment of bone density will further contribute to increase physical fitness. The effects of T replacement therapy (TRT) are strongly influenced by age, training, and also pharmacogenetics: the CAG repeat polymorphism in exon 1 of the androgen receptor (AR) gene modulates androgen effects. In vitro, transcription of androgen-dependent target genes is attenuated with increasing length of triplet residues. Clinically, the CAG repeat polymorphism causes significant modulations of androgenicity in healthy eugonadal men as well as efficacy of TRT. Thresholds at which T treatment should be initiated, as well as androgen dosage, could be tailored according to this polymorphism.
Affect ; Body Composition ; Erythropoiesis ; Glucose ; metabolism ; Hormone Replacement Therapy ; Humans ; Male ; Pharmacogenetics ; Polymorphism, Genetic ; Receptors, Androgen ; genetics ; physiology ; Testosterone ; administration & dosage ; pharmacology

To demonstrate the effect of AB serum on terminal erythroid differentiation ex vivo.
 Methods: After separation of CD34+ cells from cord blood, the cells were cultured and divided into a control group and an experimental group. The effects of AB serum were examined by the expressions of different markers (GPA, Band3 and α4-integrin) for erythroblast differentiation and enucleation by flow cytometry. 
 Results: The CD34+ cells were successfully differentiated to enucleated red blood cells. There were evident differences among the expressions of GPA, Band3 and α4-integrin between the 2 groups. The percentage of GPA positive cells in the experimental group was bigger than that in the control group in every time point. The expression of Band3 in the experimental group was higher than that in the control group. The expression of α4-integrin in the experimental group was lower than that in the control group. In addition, the enucleation rate in the experimental group was higher than that in the control group.
 Conclusion: AB serum can promote the cell differentiation and enucleation during terminal erythroid differentiation in vitro.
ABO Blood-Group System ; blood ; physiology ; Anion Exchange Protein 1, Erythrocyte ; metabolism ; Antigens, CD34 ; blood ; Cell Differentiation ; genetics ; physiology ; Cell Nucleus ; Cells, Cultured ; Erythrocytes ; physiology ; ultrastructure ; Erythropoiesis ; genetics ; physiology ; Fetal Blood ; cytology ; physiology ; Flow Cytometry ; Glycophorins ; metabolism ; Humans ; Integrin alpha4beta1 ; metabolism

The chronic myelogenous leukemic K562 cell line carrying Bcr-Abl tyrosine kinase is considered as pluripotent hematopoietic progenitor cells expressing markers for erythroid, granulocytic, monocytic, and megakaryocytic lineages. Here we investigated the signaling modulations required for induction of erythroid differentiation of K562 cells. When the K562 cells were treated with herbimycin A (an inhibitor of protein tyrosine kinase), ras antisense oligonucleotide, and PD98059 (a specific inhibitor of MEK), inhibition of ERK/MAPK activity and cell growth, and induction of erythroid differentiation were observed. The ras mutant, pZIPRas61leu-transfected cells, K562-Ras61leu, have shown a markedly decreased cell proliferation rate with approximately 2-fold doubling time, compared with the parental K562 cells, and about 60% of these cells have shown the phenotype of erythroid differentiation. In addition, herbimycin A inhibited the growth rate and increased the erythroid differentiation, but did not affect the elevated activity of ERK/MAPK in the K562-Ras61leu cells. On the other hand, effects of PD98059 on the growth and differentiation of K562-Ras61leu cells were biphasic. At low concentration of PD98059, which inhibited the elevated activity of ERK/MAPK to the level of parental cells, the growth rate increased and the erythroid differentiation decreased slightly, and at high concentration of PD98059, which inhibited the elevated activity of ERK/MAPK below that of the parental cells, the growth rate turned down and the erythroid differentiation was restored to the untreated control level. Taken together, these results suggest that an appropriate activity of ERK/MAPK is required to maintain the rapid growth and transformed phenotype of K562 cells.
Androstadienes/pharmacology ; Ca(2+)-Calmodulin Dependent Protein Kinase ; Cell Differentiation/drug effects ; Enzyme Inhibitors/pharmacology ; Erythroid Progenitor Cells/physiology* ; Erythroid Progenitor Cells/cytology ; Erythropoiesis* ; Flavones/pharmacology ; Human ; K562 Cells ; Leukemia, Myeloid/pathology ; Oligonucleotides, Antisense/pharmacology ; Quinones/pharmacology ; ras Proteins/metabolism*

OBJECTIVETo explore impaired erythropoiesis and relative inadequacy of erythropoietin production in the anemic cancer patients and the correlation of tumor necrosis factor-alpha (TNF-alpha) or interferon-gamma (IFN-gamma) with inadequate erythropoietin (EPO) response and impaired erythropoiesis in cancer patients with anemia.

METHODSFifty adult anemic and 15 non-anemic tumor patients were studied. Serum EPO levels were measured by radioimmunoassay (RIA) and serum soluble transferrin receptor (sTfR). TNF-alpha and IFN-gamma levels by enzyme-linked immunosorbent assay (ELISA). Log transformed EPO and sTfR values were used in statistical analysis. The R correlation analyses were performed.

RESULTSThe mean serum immunoreactive erythropoietin level in anemic cancer patients [(23.11 +/- 10.00) IU/L] was not significantly higher than in healthy people (P = 0.053), but significantly lower than in IDA patients with similar degree of anemia [(43.00 +/- 22.00) IU/L, P < 0.01]. Both O/P EPO [0.88 (0.54-1.10)] and O/P sTfR [0.89 (0.57-1.22)] were significantly lower in anemic cancer patients than in controls and in non-anemic cancer patients. There was no significant difference between the latter two groups. Furthermore, the expected inverse linear relation between serum EPO and hemoglobin levels was absent in the anemic cancer patients, and so did the relation between serum sTfR and hemoglobin levels. There was no correlation between O/P EPO and O/P sTfR. The serum levels of both TNF-alpha and IFN-gamma in anemic cancer patients [(25.75 +/- 26.71) ng/L, (50.49 +/- 42.12) ng/L, respectively] were significantly higher than those in healthy controls (both P < 0.01) or in nonanemic cancer patients (both 0.01 < P < 0.05), and so did between non-anemic cancer patients and controls. The serum levels of TNF-alpha were inversely correlated with hemoglobin levels (r = - 0.40, P = 0.004), O/P EPO (r = -0.32, P = 0.025) or O/P sTfR (r = -0.36, P = 0.01); while serum levels of IFN-gamma were inversely correlated with hemoglobin levels (r = -0.36, P = 0.01) or O/P sTfR (r = 0.39, P = 0.006), but not with O/P EPO. Conclusions Anemia of cancer is due to impaired erythropoiesis and relative inadequacy of EPO production. TNF-alpha might inhibit EPO production and erythropoiesis, while IFN-gamma maybe directly inhibit erythropoiesis and be independent of EPO response inadequacy.

Adolescent ; Adult ; Aged ; Anemia ; blood ; etiology ; physiopathology ; Erythropoiesis ; physiology ; Erythropoietin ; biosynthesis ; blood ; Female ; Humans ; Interferon-gamma ; blood ; Male ; Middle Aged ; Neoplasms ; complications ; Receptors, Transferrin ; blood ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo investigate the effects of combined use of low-dose hydroxyurea (HU) and sodium butyrate (NaB) on the expression of 7 globin genes (zeta, alpha, epsilon, Ggamma, Agamma, delta, and beta) in human erythroid progenitor cells.

METHODSHuman erythroid progenitor cells were cultured using a two-step liquid culture system and treated with HU and NaB either alone or in combination. The inhibitory effects of the agents on the cell growth were monitored with trypan blue exclusion assay, and the changes in the mRNA of the 7 globin genes were detected using RT-PCR.

RESULTSLow-dose HU combined with NaB resulted in significantly lower inhibition rate of the erythroid progenitor cells than routine dose HU and NaB used alone (28.56% and 38.80%, respectively, P<0.05). Compared with untreated cells (0.653-/+0.092 and 0.515-/+0.048), HU combined with NaB significantly increased the expression of Ggamma-and Agamma- mRNA (1.203-/+0.018 and 0.915-/+0.088, respectively, P<0.05), and HU and NaB used alone produced similar effects (1.305-/+0.016 and 0.956-/+0.029 for HU, and 1.193-/+0.070 and 0.883-/+0.012 for NaB, P>0.05). HU and NaB, either used alone or in combination or at different doses, caused no significant changes in the other globin genes (zeta, alpha, epsilon, delta and beta) (P>0.05).

CONCLUSIONLow-dose HU combined with NaB can up-regulate gamma globin gene expression, especially Ggamma-mRNA expression, to decrease the growth inhibition on human erythroid progenitor cells in vitro, but produces no significant effect on the expressions of zeta, alpha, epsilon, delta and beta genes.

Anemia, Sickle Cell ; genetics ; Butyrates ; administration & dosage ; pharmacology ; therapeutic use ; Cells, Cultured ; Drug Therapy, Combination ; Erythroid Precursor Cells ; cytology ; drug effects ; physiology ; Erythropoiesis ; drug effects ; Humans ; Hydroxyurea ; administration & dosage ; pharmacology ; therapeutic use ; RNA, Messenger ; genetics ; metabolism ; gamma-Globins ; genetics ; metabolism

OBJECTIVETo further characterize the differentiation inducing properties of EDRF1 and demonstrate its functional pathway involved in regulation of globin gene expression.

METHODSBy transfecting EDRF1 sense and antisense constructs into HEL cells, we identified the expression of globin and erythropoietin receptor genes by Northern blot analysis. RT-PCR and EMSA (electrophoresis mobility shift assay) were performed to monitor the expression and DNA-binding activity of erythroid specific transcription factors GATA-1 and NF-E2.

RESULTSIt was shown that when EDRF1 was overexpressed, production of alpha-globin increased. In antisense EDRF1, overexpression of HEL cells, significant loss of alpha-, gamma-globin mRNA synthesis was observed. The transcription of endogenous GATA-1 and NF-E2 mRNA expression were maintained at the same levels compared with control experiments. However, the transcription activity of GATA-1 was severely impaired. Expression of erythropoietin receptor gene was not influenced by EDRF1 gene overexpression.

CONCLUSIONThe results suggested that EDRF1 regulated alpha- and gamma-globin gene synthesis by modulating DNA-binding activity of GATA-1 transcription factor.

Cell Differentiation ; Cells, Cultured ; DNA-Binding Proteins ; genetics ; Erythroid-Specific DNA-Binding Factors ; Erythropoiesis ; physiology ; GATA1 Transcription Factor ; Gene Expression Regulation ; Globins ; genetics ; Humans ; NF-E2 Transcription Factor ; NF-E2 Transcription Factor, p45 Subunit ; RNA, Messenger ; analysis ; Transcription Factors ; genetics ; Up-Regulation