Plasma Erythropoietin Levels Research Articles

A Novel Connection Between Stress Erythropoiesis and Coagulation Activation in Sickle Cell Disease.

Abstract 905 Introduction:Sickle cell disease (SCD) is associated with a hypercoagulable state. Multiple studies show that plasma from these patients exhibit: 1) increased thrombin generation; 2) decreased levels of natural anticoagulant proteins; and 3) a defect in the activation of fibrinolysis. The mechanism of coagulation activation in SCD is presumed to be multi-factorial, with contributions from abnormal erythrocyte phospholipid asymmetry and induction of tissue factor (TF) following hemolysis. In addition, hemolysis in SCD leads to elevated levels of erythropoietin (EPO) in patients, increased reticulocyte counts and the presence of stress (or shift) reticulocytes in circulating blood. These stress reticulocytes retain expression of the α4b1 integrin and are demonstrably adhesive to vascular factors in SCD. We have previously reported that these stress reticulocytes bind to blood monocytes in SCD patients via the α4b1 integrin, but the effect of this interaction on either cell remained unknown in SCD. Objective:With the increasing evidence that hemolysis and subsequent stress erythropoiesis associates with coagulation activation, we sought to evaluate the role of erythropoietin and the effect of stress reticulocyte adhesion to monocytes on coagulation activation in SCD patients. Methods:Coagulation activation in plasma samples was examined by evaluating TF activity on microparticles derived from patients with SCD. Stress reticulocytes were visualized and enumerated from these same patients using Wright Giemsa stained blood smears counter stained with new methylene blue to detect reticulocytes. Reticulocytes were scored as a stress reticulocytes based on the amount of punctuate reticular material, cell size, and presence of nuclear material. Stress reticulocyte induction of monocyte tissue factor expression was measured by flow cytometry after incubation of THP-1 monocytic cells with purified SS RBCs or control RBCs. To determine if induced THP-1 TF expression was due stress reticulocyte binding, THP-1 TF expression was examined in the presence or absence of known inhibitors of the monocyte/stress reticulocyte interaction. TF expression on CD14+ monocytes was examined in whole blood from SCD patients using flow cytometry. Plasma erythropoietin levels were quantified by ELISA. Results:We found that direct binding of the stress reticulocyte increased THP-1 TF expression 2.5 fold. This increase in TF expression was completely ablated by function blocking antibodies against the α4 integrin, but not by an isotype-matched control IgG. In whole blood samples, we also found increased TF expression on CD14+ monocytes with stress reticulocytes directly bound, compared to those monocytes in the same patient without stress reticulocytes bound (p = 0.002, n =3).We noted a strong correlation between stress reticulocyte count and TF activity on plasma microparticles in SCD (rspearman = 0.8656, CI = 0.5382 – 0.9660, p = 0.0006, n=11). Furthermore, we found that EPO induced α4b1 activation on the stress reticulocyte. This activation may promote both adhesion to the monocyte and an increase in TF expression. Consequently, we noted a strong trend towards an association of EPO with microparticle TF activity in SCD (rspearman= 0.5740, CI=-0.06 – 0.8780, p=0.068, n= 11) suggesting that EPO, by promoting the interaction between the stress reticulocyte and the monocyte, may contribute to TF activity in SCD. Conclusion:Taken together, we find that stress reticulocyte adhesion to monocytes and monocytic cells induces TF expression and may promote TF activity in patients. These data suggest a novel connection between stress erythropoiesis and coagulation activation in SCD. Disclosures:No relevant conflicts of interest to declare.

Erythropoietin and the skin: a role for epidermal oxygen sensing?

Erythropoietin (EPO), long appreciated as the chief endocrine regulator of red blood cell formation, is now recognized to exert many additional functions outside the bone marrow. Thus, the quest is on to define the full range of EPO functions in the physiology and pathology of non-hematopoietic tissues. Two recent studies in man and mice have highlighted the importance of the mammalian skin as one peripheral tissue with a previously unsuspected role in EPO biology; both, as a target and as a source of EPO. In addition, the skin has been proposed to function as an oxygen sensor. The present hypothesis essay critically reviews the currently available evidence for this and provides a unifying theoretical scenario for intracutaneous EPO functions and for a potential role of the skin in the control of EPO production. Mainly, we propose that the skin itself directly contributes to the up-regulation of EPO plasma levels in response to hypoxia.

Increased numbers of small circulating endothelial cells in renal cell cancer patients treated with sunitinib

Mature circulating endothelial cell (CEC) as well as endothelial progenitor populations may reflect the activity of anti-angiogenic agents on tumor neovasculature or even constitute a target for anti-angiogenic therapy. We investigated the behavior of CECs in parallel with hematopoietic progenitor cells (HPCs) in the blood of renal cell cancer patients during sunitinib treatment. We analyzed the kinetics of a specific population of small VEGFR2-expressing CECs (CD45(neg)/CD34(bright)), HPCs (CD45(dim)/CD34(bright)), and monocytes in the blood of 24 renal cell cancer (RCC) patients receiving 50 mg/day of the multitargeted VEGF inhibitor sunitinib, on a 4-week-on/2-week-off schedule. Blood was taken before treatment (C1D1), on C1D14, C1D28, and on C2D1 before the start of cycle 2. Also plasma VEGF and erythropoietin (EPO) were determined. Remarkably, while CD34(bright) HPCs and monocytes decreased during treatment, CD34(bright) CECs increased from 69 cells/ml (C1D1) to 180 cells/ml (C1D14; P = 0.001) and remained high on C1D28. All cell populations recovered to near pre-treatment levels on C2D1. Plasma VEGF and EPO levels were increased on C1D14 and partly normalized to pre-treatment levels on C2D1. In conclusion, opposite kinetics of two circulating CD34(bright) cell populations, HPCs and small CECs, were observed in sunitinib-treated RCC patients. The increase in CECs is likely caused by sunitinib targeting of immature tumor vessels.

Erythropoietic Stimuli and Response in Hereditary Spherocytosis

Hereditary Spherocytosis (HS) is the most common non-immune hemolytic anemia in Europe. HS ranges from assymptomatic to transfusion-dependent hemolytic anemia and is clinically classified as mild, moderate or severe. Clinical, biochemical and molecular heterogeneous patterns are HS trademarks. In a previous work, we reported that in HS patients the erythropoietic response appears to be impaired in the more severe cases of the disease, since erythropoietin (EPO) levels did not correlate with reticulocyte count or with reticulocyte production index (RPI) [Rocha S. et al. (2005) Br J Haematol. 131(4):534]. It is known that spherocytes are removed by splenic macrophages. The activation of these cells is associated with cytokine release, namely, tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ), both known as EPO inhibitors. The aim of our work was to evaluate the erythropoietic stimuli and response according to HS severity and to clarify the role of these cytokines in HS. We studied 31 HS patients and 25 healthy individuals as the control group. The HS group included only unsplenectomised patients classified as presenting mild (n=19), moderate (n=9) or severe HS (n=3) according to the Guidelines for the diagnosis and management of hereditary spherocytosis [Bolton-Maggs et al. (2004) Br J Haematol. 126(4):455]. The basic hematological study was performed in all samples, as well as the reticulocyte count and RPI calculation; the plasma levels of EPO and soluble transferrin receptor (sTfR) (as markers of erythropoietic stimuli), of bilirubin (as a marker of hemolysis) and of TNF-α and IFN-γ (known as EPO inhibitors) were also determined. Data was analysed according to the severity of HS and versus the control group. Erythrocyte count, hemoglobin concentration, hematocrit and mean cell volume were found to be significantly lower in patients than in controls and their values decreased with HS severity; for MCHC, RDW, reticulocytes, RPI, bilirubin, EPO and sTfR patients presented significantly higher values than controls, and their values increased with HS severity. However, the increment in EPO and sTfR levels was more marked than for reticulocytes and RPI. As for TNF-α and IFN-γ no differences were found between patients and controls or between HS severities; no correlations with the other studied variables were observed. In mild HS patients, sTfR was found to be statistically and positively correlated with reticulocytes (r=0.783; p<0.001), RPI (r=0.748; p<0.001) and bilirubin (r=0.870; p<0.001); in patients with more severe forms (moderate and severe HS) these correlations were lower and only a statistically and positively correlation between sTfR and reticulocytes (r=0.657; p<0.05) was found. Our results confirm the inadequate erythropoietic response in the more severe cases of HS, given that, the erythropoietic stimuli (shown by higher EPO, sTfR and indirectly, by bilirubin levels) was not able to trigger an adequate erythropoietic response as shown by the reticulocyte number and RPI, as occured in mild HS patients. Our hypothesis, that this disturbance could be due to an increase in TNF-α and IFN-γ, was not confirmed, as we did not found any significant increase in these cytokines that could explain the non adequate erythropoietic response in moderate/severe HS patients. In conclusion, the erythropoietic stimuli seem to increase with HS severity; however, the response to that stimulus appears to be impaired in the more severe cases of HS. Further studies are needed to clarify this erythropoietic disturbance in HS patients, which may contribute to the severity of the clinical presentation of the disease.

Increased Fetal Plasma and Amniotic Fluid Erythropoietin Concentrations: Markers of Intrauterine Hypoxia

Tissue hypoxia is the major stimulus of erythropoietin (EPO) synthesis in fetuses and adults. Since EPO does not cross the placenta and is not stored, fetal plasma and amniotic fluid levels indicate EPO synthesis and elimination. Acutely, the rate and magnitude of the increase in plasma EPO levels correlate with the intensity of hypoxia. Amniotic fluid EPO levels correlate with cord plasma levels in normal and abnormal pregnancies, with fetal plasma EPO levels in humans averaging 2.6 times higher than the corresponding amniotic fluid EPO levels. Recent experimental and clinical studies demonstrate that EPO has neuroprotective effects related to its anti-apoptotic and vascular growth-promoting properties. Although under basal conditions the fetal kidneys are the main site of EPO production, during hypoxia recent experimental data indicate an important role of the placenta. Amniotic fluid EPO levels have been shown to increase exponentially during fetal hypoxia in preeclamptic, diabetic and Rh-immunized pregnancies, to correlate inversely with cord blood pH, pO₂ and base excess and to predict neonatal morbidities and NICU admission. As an indicator of chronic intrauterine hypoxia, fetal EPO measurements have increased our knowledge about the pathogenesis and importance of intrauterine growth restriction, macrosomia, diabetic pregnancy, prolonged pregnancy, meconium staining, fetal hemorrhage, fetal anemia, maternal smoking and alcohol consumption, abnormal fetal heart rate and abnormal Doppler flow patterns. While the clinical utility of fetal amniotic fluid and plasma EPO measurements in the management of high-risk pregnancies and their offspring is promising, adequately powered clinical trials are urgently needed.

Acellular haemoglobin attenuates hypoxia-inducible factor-1α (HIF-1α) and its target genes in haemodiluted rats

Hb (haemoglobin)-based blood substitutes represent a class of therapeutics designed to correct oxygen deficit under conditions of anaemia and traumatic blood loss. The influences of these agents on HIF-1alpha (hypoxia-inducible factor-1alpha) target genes involved in adaptation to hypoxia have so far not been studied. In the study presented here, rats underwent 80% ET (exchange transfusion) with either HS (hetastarch) or a polymerized Hb OG (Oxyglobin). HS induced dramatic EPO (erythropoietin) gene transcription, reaching a maximum at 4 h post-ET. In contrast, OG suppressed EPO transcription until approx. 24 h post-ET. Large plasma EPO levels that were observed post-ET with HS were significantly blunted in animals transfused with OG. OG, unlike HS, induced a sharp increase in HO-1 (haem oxygenase-1) transcription at 4 h, which declined rapidly within 24 h, whereas modest increases in iNOS [inducible (nitric oxide synthase)] and constitutive NOS [eNOS (endothelial NOS)] were detected over the control. Our results demonstrate for the first time that severe haemodilution-induced erythropoietic responses in kidneys were attenuated by a low-oxygen-affinity cell-free Hb and suggest that tissue-specific oxygen-sensing pathways can be influenced by allosterically modified Hbs.

The micronucleus test and erythropoiesis: Effects of cyclic adenosine monophosphate (cAMP) on micronucleus formation

The aim of this study was to determine the mechanism of the rodent bone marrow micronucleus test in relation to erythropoiesis. We have previously reported that an acceleration of erythropoiesis increases the frequency of micronucleated polychromatic erythrocytes (MPCE) induced by mutagens. The blood plasma erythropoietin level increased after the injection of N6-2- O-dibutyladenosine-3′,5′-cyclic monophosphate into adenosine 3′,5′-cyclic monophosphate (cAMP) at a dose of 500 mg/kg. A peak of erythropoietin induction was observed 3 h after the injection of cAMP. cAMP itself did not induce any micronuclei in erythroblasts of BALB/c mice. So, the frequency of MPCE did not increase after injection of cAMP. The highest frequency of MPCE and the dose–response relationship between the cAMP doses and micronucleus frequency were observed 30 h after injection of mitomycin C (MMC) in mice which had been administered cAMP 24 h previously . The highest effect of cAMP on the increase of MPCE was observed when cAMP was given 24 h before MMC injection, thus indicating that accelerating the multiplication of erythroblasts increases the frequency of MPCE induced by mutagens. The induction of MPCE in the bone marrow by three other chemicals (carboquone, 5-fluorouracil, and vincristine) also increased after pretreatment with cAMP. Our results suggest that the increase of MPCE induced by mutagens can be amplified following the acceleration of erythropoiesis by pretreatment with cAMP.

Transgenic expression of JAK2V617F causes myeloproliferative disorders in mice

AbstractThe JAK2V617F mutation was found in most patients with myeloproliferative disorders (MPDs), including polycythemia vera, essential thrombocythemia, and primary myelofibrosis. We have generated transgenic mice expressing the mutated enzyme in the hematopoietic system driven by a vav gene promoter. The mice are viable and fertile. One line of the transgenic mice, which expressed a lower level of JAK2V617F, showed moderate elevations of blood cell counts, whereas another line with a higher level of JAK2V617F expression displayed marked increases in blood counts and developed phenotypes that closely resembled human essential thrombocythemia and polycythemia vera. The latter line of mice also developed primary myelofibrosis-like symptoms as they aged. The transgenic mice showed erythroid, megakaryocytic, and granulocytic hyperplasia in the bone marrow and spleen, displayed splenomegaly, and had reduced levels of plasma erythropoietin and thrombopoietin. They possessed an increased number of hematopoietic progenitor cells in peripheral blood, spleen, and bone marrow, and these cells formed autonomous colonies in the absence of growth factors and cytokines. The data show that JAK2V617F can cause MPDs in mice. Our study thus provides a mouse model to study the pathologic role of JAK2V617F and to develop treatment for MPDs.

The Incidence of Placental Abnormalities, Maternal and Cord Plasma Malondialdehyde and Vascular Endothelial Growth Factor Levels in Women with Gestational Diabetes Mellitus and Nondiabetic Controls

Background/Aims: To evaluate the incidence of placental abnormalities, cord plasma erythropoietin (EPO) levels and nucleated red blood cell (NRBC) counts, maternal and cord plasma malondialdehyde (MDA) and vascular endothelial growth factor (VEGF) levels in women with gestational diabetes mellitus (GDM) and nondiabetic controls. Methods: Twenty-two women with GDM, diagnosed according to the current criteria of the American Diabetes Association, were compared with 22 controls. Maternal and cord blood and placental samples were obtained from all pregnant women. Cord plasma EPO levels and NRBC counts, maternal and cord plasma MDA and VEGF levels were determined. Placental tissues were examined histologically. Results: Maternal and cord plasma levels of MDA and cord plasma EPO levels and NRBC counts were significantly higher in GDM pregnancies (p < 0.01). The presence of villous immaturity, chorangiosis and ischemia were significantly increased in the placentas of women with GDM (p < 0.05). The maternal and cord plasma levels of MDA increased (p = 0.007 and p = 0.001, respectively), whereas VEGF decreased (p = 0.046 and p = 0.001, respectively) with the presence of villous immaturity. Conclusion: The complex process of villous development and maturity might be influenced by the maternal and fetal oxidative and angiogenetic milieu. The placenta that shows abnormalities in angiogenesis and maturation may lead to fetal hypoxia and compromise.

Reduced erythroid cell and erythropoietin production in response to acute anemia in prion protein-deficient (Prnp−/−) mice

Cellular prion protein (PrPc) participates in the pathogenesis of prion diseases but its normal function remains unclear. PrPc is expressed on hematopoietic cells, including erythroid precursors. We investigated the role of PrPc in erythropoiesis in vivo with phenylhydrazine-induced acute anemia. Induction of equivalent anemia in wild-type (WT) and Prnp−/− mice resulted in a higher number of circulating reticulocytes, hematocrits and spleen weights in WT mice than in Prnp−/− mice on Days 5 and 7. Examination of bone marrow erythroid precursor cells (Ter119+) on Day 5 revealed no significant differences in the number of these cells between the two types of animals. However, a higher percentage of Ter119+ cells were going through apoptosis in Prnp−/− mice than in WT mice. Plasma erythropoietin (Epo) levels and Epo mRNA in kidneys peaked on Day 3 in response to anemia for both types of animals but rose less in Prnp−/− (5500 pg/ml ) than in WT (18,000 pg/ml) animals. Administration of recombinant human Epo to mice produced an equivalent reticulocyte response in both types of animals suggesting that the potential for erythroid generation is intact in Prnp−/− animals. These observations indicate that PrPc may modulate tissue hypoxia-sensing mechanisms or effect hypoxia target gene expression.

Consensus recommendations

Consensus recommendations

Link between erythropoietin release and mobilization of endothelial progenitor cells in acute myocardial infarction The opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology.

Myocardial infarction (MI) is associated with the increase in plasma levels of inflammatory and haematopoietic cytokines and mobilization of a heterogenous population of cells which consists predominantly of committed lineages (monocytes, polymorphonuclear granulocytes, and lymphocytes), as well as numerous types of stem/progenitor cells [endothelial progenitor cells (EPCs), haematopoietic stem cells (HSCs), and mesenchymal stem cells (MSCs)]. The number of circulating EPCs may have a prognostic value; however, this concept remains to be proved in large prospective studies.1,2 The number of circulating EPCs and mature endothelial cells (ECs) supposedly reflects the vascular endothelial injury and the repair mechanisms activated to restore the endothelial integrity. The article by Ferrario et al. 3 investigates the haemoglobin-independent increase of the plasma levels of erythropoietin (Epo) in patients with acute MI and seeks to confirm the hypothesis that changes of Epo levels are associated with the mobilization of EPCs and ECs from the bone marrow. The paper by Ferrario et al. confirms previous work by the same group, published in 2005, describing the mobilization of heterogenous population of progenitor cells in patients with acute MI.4 In the present paper the authors identify two populations of immature EPCs (CD34+CD133+VEGFR2+ and CD34+CD117+VEGFR2+), more mature EPCs, and mature ECs (CD34+VEGFR2+). This study continues the search for humoral factors involved in EPC mobilization following acute myocardial ischaemia and vascular injury. One of the important issues … *Corresponding author. Tel: +48 604188669; fax: +48 32 2523930. E-mail address: wojwoj{at}mp.pl

Early haemoglobin-independent increase of plasma erythropoietin levels in patients with acute myocardial infarction

We studied plasma erythropoietin (EPO) levels and their relation with CD34(+)VEGFR-2(+) (mature and progenitor endothelial cells) and CD34(+) CD133(+)VEGFR-2(+), or CD34(+) CD117(+)VEGFR-2(+) (early/immature endothelial progenitors) cells in patients with acute myocardial infarction (AMI). Fifty AMI patients undergoing percutaneous coronary intervention (PCI) within 6 h of symptom onset were enrolled. EPO, measured by ELISA, and cell subsets, by cytofluorimetric analysis, were evaluated before PCI, 24 h and 7 days afterwards. Forty-five healthy subjects (CTRLs) were studied. Plasma EPO levels were higher in AMI patients at admission, 24 h, and 7 days (P = 0.04, P = 0.0001, P = 0.001, respectively) than in CTRLs. No correlation was evidenced between EPO and haemoglobin (Hb) or haematocrit at admission or 24 h after AMI. Differently, both Hb and haematocrit inversely correlated with EPO at day 7 (P = 0.0016, P = 0.029, respectively). Plasma EPO levels correlated with CD34(+)CD133(+)VEGFR-2(+) cells at day 7 (P = 0.03). AMI patients have increased plasma EPO levels until day 7. In the early phase, plasma EPO levels are Hb-independent; at day 7, an Hb-modulated increase of EPO correlates with the percentage of CD34(+)CD133(+)VEGFR-2(+) cells.

Cochrane review: Late erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants

Cochrane review: Late erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants

Effects of erythropoietin on erythrocyte deformability in non‐transfused preterm infants

Suppression of erythropoiesis due to low plasma erythropoietin levels is an important factor in the development of anaemia of prematurity. Premature infants may therefore be treated with recombinant human erythropoietin (rhEPO). This prospective, randomised and controlled study was designed to find out whether rhEPO treatment improves erythrocyte deformability in preterm infants. Sixteen infants were treated with rhEPO (250 IU/kg three times weekly) a total of 15 times beginning on day of life 5 whereas fifteen infants served as controls. Haemoglobin concentration, haematocrit, reticulocyte count, ferritin level and erythrocyte deformability were measured on days 5, 14, 28, 42 and 63. Erythrocyte elongation was determined as an indicator of erythrocyte deformability using a shear stress diffractometer (Rheodyn SSD) at shear forces of 0.3 to 60 Pa. Haemoglobin concentration was significantly higher on days 28 and 42 and reticulocyte percentage on day 28 in the rhEPO group compared to the controls. Serum ferritin was lower in the rhEPO group on day 28. Erythrocyte deformability was significantly increased on days 28 and 42 in the infants receiving rhEPO. We found a strong relationship between erythrocyte elongation and reticulocyte count. RhEPO markedly increases the erythropoiesis in preterm infants in the critical first weeks of life and the anaemia of prematurity is obviously reduced. The erythrocyte deformability improved under rhEPO treatment. Erythrocyte deformability was significantly related to the reticulocyte count indicating that the improvement of erythrocyte deformability was due to the formation of well-deformable young erythrocytes.

A family with hereditary thrombocythaemia and normal genes for thrombopoietin and c‐Mpl

Hereditary thrombocythaemia (HT) is an inherited autosomal dominant disorder. Recent studies reported six different mutations, four within the thrombopoietin (TPO) gene and two within c-Mpl (TPO receptor) gene in six unrelated families with HT. This study investigated the molecular basis of hereditary thrombocythaemia in an Israeli-Jewish family. We screened the genes for TPO and c-Mpl by amplification and sequencing of all the corresponding exons including exon/intron boundaries and promoters. In addition, plasma levels of TPO and erythropoietin (EPO) were measured. No abnormality in the TPO/c-Mpl genes has been identified in affected HT family members. Plasma TPO and EPO levels were found to be normal/low or normal respectively in the individuals affected. In conclusion, lack of a molecular lesion within either TPO or cMpl genes indicate that HT may be caused by factors other than TPO-cMpl axis in this family.

Effects of Azathioprine and Mycophenolate Mofetil—Immunosuppressive Regimens on the Erythropoietic System of Renal Transplant Recipients

Introduction Azathioprine (AZA) and mycophenolate mofetil (MMF) are major immunosupressants used to prevent rejection following renal transplantation. Bone marrow suppression is a potential adverse effect of these agents manifesting itself as leukopenia, thrombocytopenia, and anemia. The aim of this study was to compare the effects of AZA versus MMF immunosuppressive regimens on the erythropoietic system of renal transplant recipients within 6 months after transplantation. Methods Eighty kidney allograft recipients who were on AZA ( n = 40) or MMF ( n = 40) plus cyclosporine and prednisolone were enrolled in this study. Hematologic parameters included red blood cell counts, hemoglobin (Hb), hematocrit, mean corpuscular volume, mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) and were measured before and at 1 week, as well as 1 and 6 months posttransplantation. Plasma erythropoietin level was measured at the end of 6 months. Statistical analysis was performed with Student t test; a P value less than .05 was considered significant. Results There was no significant difference between the two groups regarding red blood cell counts. High Hb level was noted at 1 and 6 months posttransplantation among patients who received MMF. MCH and MCHC were higher among patients on MMF compared with those on AZA at 1 week and 1 month posttransplant. Although the mean plasma erythropoietin levels in AZA-treated patients were higher than those of MMF-treated patients, the trend did not reach statistical significance ( P = .066). Conclusion MMF administration was apparently associated with a higher level of hemoglobin compared with AZA among renal allograft recipients with good graft function at 6 months posttransplantation.

Plasma Prohepcidin Positively Correlates with Hematocrit in Chronic Hemodialysis Patients

Background/Aims: Experimental studies have demonstrated interleukin-6 and iron load induce expression of hepcidin (an iron regulatory peptide), whereas anemia and erythropoietin (EPO) suppress its expression. We are the first to explore the relationships of plasma prohepcidin (the pro-hormone of hepcidin) in patients undergoing chronic hemodialysis (HD). Methods: We enrolled 71 chronic HD patients. During the preceding 3 months before enrollment, they all had steady weekly levels of haematocrit (Hct) and fixed subcutaneous doses of recombinant human EPO. Plasma levels of prohepcidin, proinflammatory cytokines, and EPO were determined by ELISA kits. Results: Of the patients, prohepcidin levels correlated positively with Hct, and negatively with interleukin-6 and EPO. Examined by a multivariate lineal regression method, we found Hct was the only significant predictor of plasma prohepcidin level. However, prohepcidin had no significant correlation with iron profiles. Conclusion: Our findings suggest prohepcidin expression in chronic HD patients might be positively regulated by Hct.

Theophylline Improves Early Allograft Function in Rat Kidney Transplantation

Several previous studies have demonstrated a beneficial effect of the adenosine receptor (AdoR) antagonist theophylline in different forms of acute renal failure in laboratory animals and in humans. Therefore, we wanted to test whether theophylline can also improve impaired allograft function following ischemia reperfusion injury in experimental kidney transplantation (KT). Orthotopic transplantation of the left kidney was performed from Fisher 344 into Lewis rats. All transplanted rats received daily cyclosporine (5 mg/kg). The effect of theophylline treatment (10 mg/kg) on graft function was compared with appropriate controls on day 5 after KT by assessment of glomerular filtration rate (GFR) (inulin clearance). On day 5, GFR of allografts in control rats was 0.23 +/- 0.05 ml/min/g kidney weight (n = 10) compared with 0.50 +/- 0.09 ml/min/g in rats receiving theophylline (n = 9, p < 0.01), representing a 2-fold increase in GFR. Renal AdoR A(1) mRNA content was significantly increased in both KT groups compared with their respective control groups, whereas mRNA of AdoR A(2a), A(2b), and A(3) were found to be unchanged. Theophylline did not affect significantly interstitial infiltration of the graft by monocytes/macrophages and T-cells. Likewise, serum cytokines [interleukin (IL)-2, IL-6, IL-10, tumor necrosis factor-alpha] and erythropoietin plasma levels were not different among the allograft groups. The present study demonstrates that theophylline remarkably improved early renal allograft function in rats undergoing KT without influencing cytokine serum patterns or tissue inflammation. Since theophylline is a commonly used medication in humans, clinical studies in patients undergoing KT are warranted.

Insulin-like growth factor-I stimulates erythropoiesis when administered enterally

Background: Insulin-like growth factors I and II (IGF-I and IGF-II) are potent growth factors involved in development. IGF-I stimulates proliferation of erythropoietic progenitors and parenteral IGF-I administration stimulates in vivo erythropoiesis in animals. IGF-I and IGF-II are both present in mammalian milks and when milk-borne, are resistant to neonatal gastrointestinal degradation. Whether milk-borne IGF-I or IGF-II regulates neonatal erythropoiesis in not known. We hypothesized that physiological doses of enteral IGFs stimulate erythropoiesis in suckling rats.Methods: Eight day-old Sprague Dawley rats were artificially fed for 4 days with rat milk substitute (RMS) or RMS supplemented with physiological levels of IGF-I or IGF-II. Rats fed IGF-I and IGF-II were compared to control RMS. Blood and marrow were collected; measures of red cell mass, measures of erythropoietic stimulus, and indices of iron status were measured.Results: Rats fed IGF-I had higher hemoglobin (Hb) levels (100 ± 10 g/l), compared to those fed RMS (94 ± 9) or IGF-II (91 ± 6), p < 0.001. After IGF-I supplementation, red blood cell counts (RBC) (p < 0.04) and hematocrits (p < 0.002) were also higher. Plasma erythropoietin (Epo) levels, reticulocytes, plasma iron and erythrocyte iron incorporation were similar.Conclusion: Intact enteral IGF-I reaches distal erythropoietic tissue resulting in greater red cell mass, but not by increasing plasma Epo levels or by altering cellular iron transport.