guanosine-diphosphate and Anemia

Hepcidin, master regulator of iron homeostasis, causes anemia under infectious and inflammatory conditions by reducing intestinal absorption of iron with decreased release of iron from macrophages and liver despite adequate iron stores leading to Anemia of Inflammation (AI). Many therapeutic trials have been carried out but none have been effective due to its adverse effects. In present study, we discover that Guanosine 5'-diphosphate (GDP) encapsulated in lipid vesicle (NH+) was found to inhibit NF-ҝB activation by limiting phosphorylation and degradation of IҝBα, thus, attenuating IL-6 secretion from macrophage cells. Moreover, the suppressed IL-6 levels down regulated JAK2/STAT3 pathway with decrease inflammation-mediated Hamp mRNA transcription (HepG2) and increase iron absorption (Caco2) in HepG2/Caco2 co-culture model. Analogous results were obtained in acute and chronic AI mice model thus, correcting haemoglobin level. These results proved NH + GDP as novel therapeutic agent to overcome limitations and suggests it as potential drug to ameliorate AI.

Topics: Anemia; Animals; Caco-2 Cells; Cell Line, Tumor; Disease Models, Animal; Guanosine; Guanosine Diphosphate; Hep G2 Cells; Hepcidins; Humans; Inflammation; Interleukin-6; Iron; Janus Kinase 2; Liposomes; Macrophages; Male; Mice; Mice, Inbred BALB C; NF-kappa B; Phosphates; Signal Transduction; STAT3 Transcription Factor; U937 Cells

To explore the mechanism of erythropoietin action on differentiation of erythroblasts, we have examined its effect on regulating phosphorylation of the 25-kD mRNA cap binding protein (eIF-4E). Erythroblasts from the spleens of mice infected with the anemia strain of Friend virus (FVA cells) were studied. Erythropoietin stimulated phosphorylation of eIF-4E in FVA cells within 30 minutes, and this effect was maximal at 60 minutes. Phosphoamino acid analysis and tryptic phosphopeptide map analysis of eIF-4E isolated from both control and erythropoietin-treated cells identified a predominant phosphopeptide containing phosphoserine. However, when cells were incubated with 1 muM okadaic acid, eIF-4E was phosphorylated on both serine and threonine residues and three additional tryptic phosphopeptides were detected. We also identified a 37-kD phosphoprotein (pp37) that bound specifically to the m7GTP cap structure and coimmunoprecipitated with eIF-kD protein was phosphorylated on both serine and threonine residues. These results indicate that phosphorylation of eIF-4E is a target in erythropoietin-initiated signal transduction events and that this phosphorylation precedes observable effects of erythropoietin on macromolecular biosynthesis. Although of pp37 remains to be studied, it may represent a developmentally regulated mRNA cap binding protein.

Topics: Anemia; Animals; Erythroblasts; Erythropoietin; Ethers, Cyclic; Eukaryotic Initiation Factor-4E; Female; Friend murine leukemia virus; Guanosine Diphosphate; Guanosine Triphosphate; Mice; Molecular Weight; Okadaic Acid; Peptide Initiation Factors; Phosphoproteins; Phosphorylation; RNA Caps; RNA, Messenger; Spleen; Tetradecanoylphorbol Acetate

The hematological parameters of young (2-month-old) and old (2-year-old) mice were compared. No differences could be detected with the exception of an increased percentage of reticulocytes in the old animals suggesting that anemia in senescent mice does not occur. Red blood cell mean half-life in old mice was 8 +/- 0.8 days compared to 12 +/- 1 days in young mice. This reduced survival of red blood cell is not due to a different rate of cell phagocytosis in the reticulohistiocytic system of young and old animals since erythrocytes from young mice have the same mean half-life when injected both in young and old animals and vice versa. Thus, the old mice have a reduced red cell life-span but the same hematocrit of the young, suggesting that old animals possess a chronologically younger population of erythrocytes than do young animals. This has been confirmed by measuring the specific activities of some red blood cell age-dependent enzymes (hexokinase, glucose-6-phosphate dehydrogenase, pyruvate kinase) that were found to be higher in the older animals, and by the separation of erythrocytes into different density (age) groups by Percoll/albumin density gradient centrifugation. However, the erythrocytes osmotic fragility, and the cellular contents of adenine and pyridine nucleotides, as well as the content of 2,3-diphosphoglycerate and reduced glutathione, show that circulating erythrocytes in old animals constitute an heterogeneous cell population whose properties cannot be explained on the basis of a chronologically younger erythrocyte population. Furthermore, evaluation of cell components in hemopoietic tissues have shown an increased porportion of erythroid precursor cells in old animals confirming that old mice compensate for reduced red cell survival with an increased erythropoiesis.

Topics: Aging; Anemia; Animals; Bone Marrow Cells; Erythrocyte Aging; Erythrocytes; Guanosine Diphosphate; Hexokinase; Mice; Mice, Inbred BALB C; Osmotic Fragility; Pyruvate Kinase

Changes of the density, MCV, MCHC, RNA-concentration and the activities of the enzyme G6PD and ASAT due to maturation and aging of rbc were investigated by repeated density gradient separation of these cells during a bleeding anaemia of the rabbit. The mean density of reticulocytes and erythrocytes decreases during the course of the anaemia by 14 and 10 g/l respectively. The difference between the density of both cell types increases from 3 to 6 to 12 g/l during the anaemia. Maturation and aging of rbc are characterized by an increase of the MCHC from 200 to 350 g/l cells and the decrease of MCV by 10-25%. The RNA concentration and the ASAT activity show an almost parallel behaviour in cells of different densities during the anaemia. Remarkable differences are observed between the ASAT activity and the G6PD activity: The G6PD activity decreases mainly during the aging process and almost not during the maturation, while the ASAT activity falls constantly during maturation and aging. As observed in former studies we could distinguish and isolate 4 characteristic populations of reticulocytes in certain density fractions during the anaemia: Normal young reticulocytes, line 2 reticulocytes, megaloreticulocytes and reticulocytes of high density.

Topics: Anemia; Animals; Aspartate Aminotransferases; Cell Separation; Centrifugation, Density Gradient; Erythrocyte Aging; Erythrocyte Indices; Erythrocytes; Erythropoiesis; Guanosine Diphosphate; Hemorrhage; Rabbits; RNA; Time Factors