losartan-potassium and Anemia--Hemolytic--Congenital

Congenital hemolytic anemias (CHAs) are a heterogeneous group of rare hereditary conditions including defects of erythrocyte membrane proteins, red cell enzymes, and disorders due to defective erythropoiesis. They are characterized by variable degree of anemia, chronic extravascular hemolysis, reduced erythrocyte life span, splenomegaly, jaundice, biliary lithiasis, and iron overload. Although few data are reported on the role of the immune system in CHAs, several immune-mediated mechanisms may be involved in the pathogenesis of these rare diseases. We reported in ~60% of patients with hereditary spherocytosis (HS), the presence of naturally-occurring autoantibodies (NAbs) directed against different membrane proteins (α- and β-spectrin, band 3, and dematin). Positive HS subjects showed a more hemolytic pattern and NAbs were more evident in aged erythrocytes. The latter is in line with the function of NAbs in the opsonization of damaged/senescent erythrocytes and their consequent removal in the spleen. Splenectomy, usually performed to reduce erythrocyte catheresis and improve Hb levels, has different efficacy in various CHAs. Median Hb increase is 3 g/dL in HS, 1.6-1.8 g/dL in pyruvate kinase deficiency (PKD), and 1 g/dL in congenital dyserythropoietic anemias (CDA) type II. Consistently with clinical severity, splenectomy is performed in 20% of HS, 45% of CDAII, and in 60% of PKD patients. Importantly, sepsis and thrombotic events have been registered, particularly in PKD with a frequency of ~7% for both. Furthermore, we analyzed the role of pro-inflammatory cytokines and found that interleukin 10 and interferon γ, and to a lesser extent interleukin 6, were increased in all CHAs compared with controls. Moreover, CDAII and enzymatic defects showed increased tumor necrosis factor-α and reduced interleukin 17. Finally, we reported that iron overload occurred in 31% of patients with membrane defects, in ~60% of CDAII cases, and in up to 82% of PKD patients (defined by MRI liver iron concentration >4 mg Fe/gdw). Hepcidin was slightly increased in CHAs compared with controls and positively correlated with ferritin and with the inflammatory cytokines interleukin 6 and interferon γ. Overall the results suggest the existence of a vicious circle between chronic hemolysis, inflammatory response, bone marrow dyserythropoiesis, and iron overload.

Topics: Anemia, Hemolytic, Congenital; Animals; Antibodies; Cytokines; Erythropoietin; Humans; Immune System; Iron; Spleen; Splenectomy

Recently, erythropoietin (EPO) was identified as regulator of fibroblast growth factor 23 (FGF23). Proteolytic cleavage of biologically active intact FGF23 (iFGF23) results in the formation of C-terminal fragments (cFGF23). An increase in cFGF23 relative to iFGF23 suppresses FGF receptor signaling by competitive inhibition. EPO lowers the i:cFGF23 ratio, thereby overcoming iFGF23-mediated suppression of erythropoiesis. We investigated EPO-FGF23 signaling and levels of erythroferrone (ERFE) in 90 patients with hereditary hemolytic anemia (www.trialregister.nl [NL5189]). We show, for the first time, the importance of EPO-FGF23 signaling in hereditary hemolytic anemia: there was a clear correlation between total FGF23 and EPO levels (r = +0.64; 95% confidence interval [CI], 0.09-0.89), which persisted after adjustment for iron load, inflammation, and kidney function. There was no correlation between iFGF23 and EPO. Data are consistent with a low i:cFGF23 ratio. Therefore, as expected, we report a correlation between EPO and ERFE in a diverse set of hereditary hemolytic anemias (r = +0.47; 95% CI, 0.14-0.69). There was no association between ERFE and total FGF23 or iFGF23, which suggests that ERFE does not contribute to the connection between FGF23 and EPO. These findings open a new area of research and might provide potentially new druggable targets with the opportunity to ameliorate ineffective erythropoiesis and the development of disease complications in hereditary hemolytic anemias.

Topics: Anemia, Hemolytic, Congenital; Erythropoietin; Fibroblast Growth Factor-23; Fibroblast Growth Factors; Humans; Iron; Peptide Hormones

The DEAH helicase RHAU (alias DHX36, G4R1) is the only helicase shown to have G-quadruplex (G4)-RNA resolvase activity and the major source of G4-DNA resolvase activity. Previous report showed RHAU mRNA expression to be elevated in human lymphoid and CD34(+) BM cells, suggesting a potential role in hematopoiesis. Here, we generated a conditional knockout of the RHAU gene in mice. Germ line deletion of RHAU led to embryonic lethality. We then targeted the RHAU gene specifically in the hematopoiesis system, using a Cre-inducible system in which an optimized variant of Cre recombinase was expressed under the control of the Vav1 promoter. RHAU deletion in hematopoietic system caused hemolytic anemia and differentiation defect at the proerythroblast stage. The partial differentiation block of proerythroblasts was because of a proliferation defect. Transcriptome analysis of RHAU knockout proerythroblasts showed that a statistically significant portion of the deregulated genes contain G4 motifs in their promoters. This suggests that RHAU may play a role in the regulation of gene expression that relies on its G4 resolvase activity.

Topics: Anemia, Hemolytic, Congenital; Animals; Bone Marrow Transplantation; Cell Cycle; Crosses, Genetic; DEAD-box RNA Helicases; Embryonic Development; Erythroblasts; Erythropoietin; Genes, Lethal; Genes, Synthetic; Green Fluorescent Proteins; Hematopoiesis; Leukopenia; Mice; Mice, Inbred C57BL; Mice, Knockout; Promoter Regions, Genetic; Protein Folding; Proto-Oncogene Proteins c-vav; Radiation Chimera; Recombinases; Thrombocytopenia

Topics: Anemia, Hemolytic, Congenital; Erythrocyte Transfusion; Erythropoietin; Female; Hemoglobins; Humans; Infant, Newborn; Recombinant Proteins

The authors report the use of high-dose recombinant erythropoietin (r-HuEPO) in a full-term newborn baby with severe postnatal rhesus hemolytic anemia (RHA). Hemoglobin (Hb) value and reticulocyte count at day 13 of life were 59 g/L and 234 x 10(9)/L, respectively. Three days after the r-HuEPO (870 U/kg/d) administration, reticulocyte count had increased more than 4-fold and Hb rose to 73 g/L. r-HuEPO was gradually decreased after 18 days of treatment. No major side effect was observed. In selected cases of severe anemia due to hemolytic disorders, transfusions may be avoided by the use of high doses of r-HuEPO.

Topics: Anemia, Hemolytic, Congenital; Erythropoietin; Female; Hemoglobins; Humans; Infant, Newborn; Recombinant Proteins; Reticulocyte Count; Rh Isoimmunization; Time Factors; Treatment Outcome

Various agents modulate hemoglobin synthesis. In vitro modulation of translation in hemoglobin chain synthesis was analysed in patients with congenital hemolytic anemia (n=32) and healthy controls (n=17).. Enriched reticulocytes were co-incubated with (3)H-leucine and cytokines or butyrate. Reversed-phase chromatography enabled separation of alpha-, beta- and gamma-globin chains. Globin chain synthesis was calculated from measured (3)H-leucine incorporation. Transferrin, erythropoietin, interleukin-3 and interferon-gamma receptors were detected by flow cytometry. Reverse-transcription polymerase chain reaction (RT PCR) was used to demonstrate changes of RNA stability.. Interleukin-3, interferon-gamma and butyrate caused a significant 2-fold increase (range 1.8-2.4; p<0.01) of the alpha- and beta-chain synthesis in congenital hemolytic anaemias. Analysis of gamma-globin chain synthesis revealed a lower, i.e. 1.4 fold increase (range 1.32 to 1.41; p<0.03). The absolute amount of globin synthesis was calculated to be 2.9 x 10(-12) g/reticulocyte/24h. After incubation with interleukin-3 the absolute additional synthesis of the alpha-globin chain reached 1.31 x 10(-12) g/reticulocyte/24h, of the beta-globin chain, 1.15 x 10(-12) g/reticulocyte/24h and of the gamma-globin chain, 0.26 x 10(-12) g/reticulocyte/24h. Butyrate and interferon-gamma had no or even an inhibiting effect on reticulocytes from normal controls, while interleukin-3 stimulated alpha- and gamma-chain synthesis (1.4 and 2.4 fold, respectively; p<0.03) suggesting an increase of fetal hemoglobin (HbF). Erythropoietin showed no stimulating influence. Membrane associated interleukin-3 receptors were detected in 0.78+/-0.14%, and interferon-gamma receptors in 0.1+/-0.015% of the red cells. Erythropoietin receptors were extremely rare (0.05+/-0.015%). The expression of transferrin receptors (CD71) correlated with the extent of globin chain stimulation. The alpha-, and beta-globin mRNA content of the reticulocytes after interleukin-3 incubation, as measured by RT-PCR, increased.. Hemoglobin chain synthesis could be modulated post-transcriptionally by interleukin-3, interferon-gamma and butyrate. Transferrin receptor and globin RNA stability might be involved in this phenomenon.

Topics: Adolescent; Adult; Anemia, Hemolytic, Congenital; Butyrates; Case-Control Studies; Cells, Cultured; Child; Child, Preschool; Cytokines; Erythropoietin; Globins; Hemoglobins; Humans; Interferon-gamma; Interleukin-3; Leucine; Middle Aged; Reticulocytes; RNA Stability; RNA, Messenger; Tritium

Topics: Anemia, Dyserythropoietic, Congenital; Anemia, Hemolytic, Congenital; Erythroblasts; Erythrocytes; Erythropoietin; Humans; Infant, Newborn; Male