Nonerythropoietic roles of erythropoietin in the fetus and neonate

Insulin, Testosterone, and Albumin in Term and Preterm Breast Milk, Donor Milk, and Infant Formula

Background: Infants have three options for feeding: their own mother’s breast milk, donor milk, or infant formula. Insulin, testosterone, total protein, and albumin levels were measured in breast milk samples from the first 6 months of lactation, in donor milk samples, and in different infant formulas. Methods: Mothers who gave birth to term (n = 19) or preterm (n = 19) infants were recruited to collect breast milk samples during the first 6 months of lactation. The Breast Milk Collection Center (Unified Health Institution, Pécs, Hungary) provided 96 donor milk (DM) samples for analysis in our study. Insulin, testosterone, total protein, and albumin levels were measured in breast milk, donor milk, and infant formulas. Results: During the first 2 months of lactation, the concentration of insulin was lower (−27.4%) while the testosterone concentration was higher (+20.8%) compared to the period between the 3rd and 6th months only in the preterm breast milk samples. The infant formulas examined did not contain insulin or testosterone. Holder pasteurization (HoP) did not influence the level of testosterone in human milk, although HoP decreased the insulin (−53.6%) and albumin (−38.6%) concentrations. Conclusions: Diet impacts the hormone intake of infants, underlining the importance of breastfeeding and the possible supplementation of formula-fed infants.

Umbilical Cord Erythroferrone Is Inversely Associated with Hepcidin, but Does Not Capture the Most Variability in Iron Status of Neonates Born to Teens Carrying Singletons and Women Carrying Multiples

BACKGROUND

The developing fetus requires adequate iron and produces its own hormones to regulate this process. Erythroferrone (ERFE) is a recently identified iron regulatory hormone, and normative data on ERFE concentrations and relations between iron status and other iron regulatory hormones at birth are needed.

OBJECTIVES

The objective of this study was to characterize cord ERFE concentrations at birth and assess interrelations between ERFE, iron regulatory hormones, and iron status biomarkers in 2 cohorts of newborns at higher risk of neonatal anemia.

METHODS

Umbilical cord ERFE concentrations were measured in extant serum samples collected from neonates born to women carrying multiples (age: 21-43 y; n = 127) or teens (age: 14-19 y; n = 164). Relations between cord blood ERFE and other markers of iron status or erythropoiesis in cord blood were assessed by linear regression and mediation analysis.

RESULTS

Cord ERFE was detectable in all newborns delivered between 30 and 42 weeks of gestation, and mean concentration at birth was 0.73 ng/mL (95% CI: 0.63, 0.85 ng/mL). Cord ERFE was on average 0.25 ng/mL lower in newborns of black as opposed to white ancestry (P = 0.04). Cord ERFE was significantly associated with transferrin receptor (β: 1.17, P < 0.001), ferritin (β: -0.27, P < 0.01), and hemoglobin (Hb) (β: 0.04, P < 0.05). However, cord hepcidin and the hepcidin:erythropoietin (EPO) ratio captured the most variance in newborn iron and hematologic status (>25% of variance explained).

CONCLUSIONS

Neonates born to teens and women carrying multiples were able to produce ERFE in response to neonatal cord iron status and erythropoietic demand. ERFE, however, did not capture significant variance in newborn iron or Hb concentrations. In these newborns, cord hepcidin and the hepcidin:EPO ratio explained the most variance in iron status indicators at birth.

Electrophysiological and inflammatory changes of CA1 area in male rats exposed to acute kidney injury: Neuroprotective effects of erythropoietin

The high mortality rate associated with acute kidney injury (AKI) is commonly due to progressive, inflammatory multiple organ dysfunction, which often involves neurological complications. The AKI-stimulated mechanisms leading to brain dysfunction are not well understood, which hinders development of new therapeutic avenues to minimize AKI-mediated neural effects. The hippocampal CA1 area is a particularly vulnerable region during AKI but the electrophysiological and inflammatory mechanisms involved in this vulnerability remain largely unknown. Here, we used immunohistochemistry to quantitatively investigate the number of astrocytes expressing glial fibrillary acidic protein (GFAP) as an indicator of inflammation, and whole cell patch clamp to evaluate electrophysiological changes in CA1 at different time points following induction of bilateral renal ischemia (BRI) in male Wistar rats. Further we evaluated the effectiveness of erythropoietin (EPO, 1000 U/kg i.p.) in mitigating BRI-associated changes. Plasma concentrations of blood urea nitrogen (BUN) were significantly enhanced at 24 h, 72 h and 1 week, and creatinine (Cr) was increased at 24 h after reperfusion, which were changes reduced by EPO. BRI led to an increase in CA1 GFAP-positive cells 24 h and 72 h, but not 1 week, after reperfusion, and EPO reversed this effect of BRI at 24 h. Additionally, BRI caused an increase in the peak amplitude and coefficient of variation of CA1 pyramidal neuronal action potentials, which were changes not seen in presence of EPO. When taken together, altered neuronal electrophysiological properties and astrogliosis could contribute to the neurological complications induced by AKI, and EPO offers hope as a potential neuroprotective agent.

Endogenous erythropoietin signaling regulates migration and laminar positioning of upper-layer neurons in the developing neocortex

Erythropoietin (EPO), the hypoxia-inducible hematopoietic hormone, has well-established neuroprotective/neurotrophic roles in the developing central nervous system and the therapeutic potential of EPO has been widely explored in clinical studies for the treatment of perinatal hypoxic brain lesion, as well as prematurity. Here, we reveal that both EPO and Epo receptor (EPOR) are expressed in the developing rat somatosensory cortex during radial migration and laminar positioning of granular and supragranular neurons. Experimental deregulation of EPO signaling using genetic approaches results in aberrant migration, as well as permanent neuronal misplacement leading to abnormal network activity and protracted sensory behavioral deficits. We identify ERK as the downstream effector of the EPO signaling pathway for neuronal migration. These findings reveal a crucial role for endogenous EPO signaling in neuronal migration, and offer important insights for understanding how the temporary deregulation of EPO could result in migration defects that lead to abnormal behavior in the adult.

Medicinal Uses of Hematopoietic Growth Factors in Neonatal Medicine

This review focuses on certain hematopoietic growth factors that are used as medications in clinical neonatology. It is important to note at the chapter onset that although all of the pharmacological agents mentioned in this review have been approved by the US Food and Drug administration for use in humans, none have been granted a specific FDA indication for neonates. Thus, in a sense, all of the agents mentioned in this chapter could be considered experimental, when used in neonates. However, a great many of the pharmacological agents utilized routinely in neonatology practice do not have a specific FDA indication for this population of patients. Consequently, many of the agents reviewed in this chapter are considered by some practitioners to be nonexperimental and are used when they judge such use to be "best practice" for the disorders under treatment.The medicinal uses of the agents in this chapter vary considerably, between geographic locations, and sometimes even within an institutions. "Consistent approaches" aimed at using these agents in uniform ways in the practice of neonatology are encouraged. Indeed some healthcare systems, and some individual NICUs, have developed written guidelines for using these agents within the practice group. Some such guidelines are provided in this review. It should be noted that these guidelines, or "consistent approaches," must be viewed as dynamic and changing, requiring adjustment and refinement as additional evidence accrues.

Erythropoietin may attenuate lung inflammation in a rat model of meconium aspiration syndrome

BACKGROUND

Inflammation is believed to play a key role in the pathophysiology of meconium aspiration syndrome (MAS).

PURPOSE OF THE STUDY

The objective was to determine whether the recombinant human Erythropoietin (rhEPO) pretreatment could attenuate meconium-induced inflammation.

MATERIALS AND METHODS

In this study, 24 ventilated adult male rats were studied to examine the effects of recombinant human EPO (rhEPO) on meconium-induced inflammation. Seventeen rats were instilled with human meconium (1.5 mL/kg, 65 mg/mL) intratracheally and ventilated for 3 hours. rhEPO (1000 U/kg) (n = 9) or saline (n = 8) was given to the animals. Seven rats that were ventilated and not instilled with meconium served as a sham-controlled group. Analysis of the blood gases, interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in blood and bronchoalveolar lavage (BAL) fluid samples, and lung tissue myeloperoxidase levels were performed.

RESULTS

Intrapulmonary instillation of meconium resulted in the increase of TNF-α (p = 0.005 and p < 0.001, respectively) and IL-8 concentrations (p < 0.001 and p < 0.001, respectively) in BAL fluid in the EPO + meconium and saline + meconium groups compared with the sham-controlled group. rhEPO pretreatment prevented the increase of BAL fluid IL-1β, IL-6, and IL-8 levels (p < 0.001, p = 0.021, and p = 0.005, respectively), and serum IL-6 levels (p = 0.036).

CONCLUSION

rhEPO pretreatment is associated with improved BAL fluid and serum cytokine levels. Pretreatment with rhEPO might reduce the risk of developing of meconium-induced derangements.

The GM-CSF/IL-3/IL-5 cytokine receptor family: from ligand recognition to initiation of signaling

Granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 are members of a discrete family of cytokines that regulates the growth, differentiation, migration and effector function activities of many hematopoietic cells and immunocytes. These cytokines are involved in normal responses to infectious agents, bridging innate and adaptive immunity. However, in certain cases, the overexpression of these cytokines or their receptors can lead to excessive or aberrant initiation of signaling resulting in pathological conditions, with chronic inflammatory diseases and myeloid leukemias the most notable examples. Recent crystal structures of the GM-CSF receptor ternary complex and the IL-5 binary complex have revealed new paradigms of cytokine receptor activation. Together with a wealth of associated structure-function studies, they have significantly enhanced our understanding of how these receptors recognize cytokines and initiate signals across cell membranes. Importantly, these structures provide opportunities for structure-based approaches for the discovery of novel and disease-specific therapeutics. In addition, recent biochemical evidence has suggested that the GM-CSF/IL-3/IL-5 receptor family is capable of interacting productively with other membrane proteins at the cell surface. Such interactions may afford additional or unique biological activities and might be harnessed for selective modulation of the function of these receptors in disease.

Cervical spinal erythropoietin induces phrenic motor facilitation via extracellular signal-regulated protein kinase and Akt signaling

Erythropoietin (EPO) is typically known for its role in erythropoiesis but is also a potent neurotrophic/neuroprotective factor for spinal motor neurons. Another trophic factor regulated by hypoxia-inducible factor-1, vascular endothelial growth factor (VEGF), signals via ERK and Akt activation to elicit long-lasting phrenic motor facilitation (pMF). Because EPO also signals via ERK and Akt activation, we tested the hypothesis that EPO elicits similar pMF. Using retrograde labeling and immunohistochemical techniques, we demonstrate in adult, male, Sprague Dawley rats that EPO and its receptor, EPO-R, are expressed in identified phrenic motor neurons. Intrathecal EPO at C4 elicits long-lasting pMF; integrated phrenic nerve burst amplitude increased >90 min after injection (63 ± 12% baseline 90 min after injection; p < 0.001). EPO increased phosphorylation (and presumed activation) of ERK (1.6-fold vs controls; p < 0.05) in phrenic motor neurons; EPO also increased pAkt (1.6-fold vs controls; p < 0.05). EPO-induced pMF was abolished by the MEK/ERK inhibitor U0126 [1,4-diamino-2,3-dicyano-1,4-bis(o-aminophenylmercapto)butadiene] and the phosphatidylinositol 3-kinase/Akt inhibitor LY294002 [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one], demonstrating that ERK MAP kinases and Akt are both required for EPO-induced pMF. Pretreatment with U0126 and LY294002 decreased both pERK and pAkt in phrenic motor neurons (p < 0.05), indicating a complex interaction between these kinases. We conclude that EPO elicits spinal plasticity in respiratory motor control. Because EPO expression is hypoxia sensitive, it may play a role in respiratory plasticity in conditions of prolonged or recurrent low oxygen.

Increased yet iron-restricted erythropoiesis in postpartum mothers

Iron deficiency in the postpartum period is common and associated with impaired quality of life. Interpretation of ordinary laboratory parameters is considered to be simple in postpartum women, as normalization of pregnancy induced physiological changes is assumed to take place in the early postpartum period. We have studied changes in erythrocyte and iron parameters during the first 11 postpartum months. Erythrocyte parameters and iron markers, serum ferritin, and soluble transferrin receptor (sTfR), and an inflammation marker, neopterin, were investigated in healthy mothers 6 weeks (n = 104), 4 months (n = 100), and 11 months (n = 43) after giving birth to a term infant. Healthy nonpregnant and nonlactating women (n = 61) were included as controls. The hemoglobin level increased throughout the first 11 postpartum months and was significantly higher from 4 months on, compared to control women. At all time points, the mothers had significantly lower mean corpuscular volume (MCV) and higher erythrocyte count and percentage of hypochromic erythrocytes. sTfR levels were significantly higher over the whole serum ferritin distribution during the first 4 postpartum months compared to the controls, indicative of an increased cell production. At 6 weeks, postpartum mothers had higher neopterin levels and this was associated with markers of a low iron status, not including sTfR. Substantial changes in erythrocyte and iron parameters were observed in the postpartum period, consistent with an increased, but iron restricted erythropoiesis. The increased erythropoietic activity was reflected in higher sTfR concentrations. Given the vital role for iron in both mothers and infants, further studies are warranted for establishing proper cut off levels for sTfR as an iron marker in postpartum women.

Comparison of oral recombinant erythropoietin and subcutaneous recombinant erythropoietin in prevention of anemia of prematurity

BACKGROUND

Premature neonates are at risk for severe anemia and erythropoietin is the most important hormone in erythropoiesis. The aim of this study was to evaluate the influence of oral recombinant human erythropoietin (rhEPO) in proving erythropoiesis in neonates.

METHODS

This was a randomized clinical trial study. Thirty neonates were enrolled from September 2007 to September 2008. The first group received oral rhEPO and Fe and the second, subcutaneous rhEPO and Fe. The patients' Hb, HCT and the need to blood transfusion were recorded. We included all infants with gestational age <34 weeks, birth weight <1500 gr, without respiratory distress (O2 Saturation> 85%, FiO2 of 30%), full feeding tolerance so that oral Fe can be administrated.

RESULTS

In first group (oral=PO), 65% of neonates were female and 35% were male, mean weight was 1140 g and mean GA was 32.6 weeks. In the second group (subcutaneous=SC), 42% were female and 58% were male. The mean weight was 1245 g and mean GA was 31.2 weeks and this was not statistically significant. In the first group, the mean Hb and HCT were 9.7±1.9 and 29.6±5.9 g/dl. In the second group, the figures were 12.5±1.7 and 38.8±5.1 which were statistically significant. There was no difference in the weight gain between two groups. In the first group, 3 neonates (20%) and in the second one, 1 neonate (15%) needed blood transfusion.

CONCLUSIONS

rhEPO administration either PO or SC could prevent anemia of prematurity but SC rout was more effective.

Erythropoetin as a novel agent with pleiotropic effects against acute lung injury

Current pharmacotherapy for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is not optimal, and the biological and physiological complexity of these severe lung injury syndromes requires consideration of combined-agent treatments or agents with pleiotropic action. In this regard, exogenous erythropoietin (EPO) represents a possible candidate since a number of preclinical studies have revealed beneficial effects of EPO administration in various experimental models of ALI. Taken together, this treatment strategy is not a single mediator approach, but it rather provides protection by modulating multiple levels of early signaling pathways involved in apoptosis, inflammation, and peroxidation, potentially restoring overall homeostasis. Furthermore, EPO appears to confer vascular protection by promoting angiogenesis. However, only preliminary studies exist and more experimental and clinical studies are necessary to clarify the efficacy and potentially cytoprotective mechanisms of EPO action. In addition to the attempts to optimize the dose and timing of EPO administration, it would be of great value to minimize any potential toxicity, which is essential for EPO to fulfill its role as a potential candidate for the treatment of ALI in routine clinical practice. The present article reviews recent advances that have elucidated biological and biochemical activities of EPO that may be potentially applicable for ALI/ARDS management.

Nonerythropoietic, tissue-protective peptides derived from the tertiary structure of erythropoietin

Erythropoietin (EPO), a member of the type 1 cytokine superfamily, plays a critical hormonal role regulating erythrocyte production as well as a paracrine/autocrine role in which locally produced EPO protects a wide variety of tissues from diverse injuries. Significantly, these functions are mediated by distinct receptors: hematopoiesis via the EPO receptor homodimer and tissue protection via a heterocomplex composed of the EPO receptor and CD131, the beta common receptor. In the present work, we have delimited tissue-protective domains within EPO to short peptide sequences. We demonstrate that helix B (amino acid residues 58-82) of EPO, which faces the aqueous medium when EPO is bound to the receptor homodimer, is both neuroprotective in vitro and tissue protective in vivo in a variety of models, including ischemic stroke, diabetes-induced retinal edema, and peripheral nerve trauma. Remarkably, an 11-aa peptide composed of adjacent amino acids forming the aqueous face of helix B is also tissue protective, as confirmed by its therapeutic benefit in models of ischemic stroke and renal ischemia-reperfusion. Further, this peptide simulating the aqueous surface of helix B also exhibits EPO's trophic effects by accelerating wound healing and augmenting cognitive function in rodents. As anticipated, neither helix B nor the 11-aa peptide is erythropoietic in vitro or in vivo. Thus, the tissue-protective activities of EPO are mimicked by small, nonerythropoietic peptides that simulate a portion of EPO's three-dimensional structure.

Novel red cell indices indicating reduced availability of iron are associated with high erythropoietin concentration and low ph level in the venous cord blood of newborns

There is evidence that an elevated erythropoietin (EPO) concentration is associated with signs of iron deficient erythropoiesis. The aim of this study was to evaluate the iron status by means of novel cellular indices and serum iron markers and to determine whether these are associated with EPO and pH in the venous cord blood of 193 full-term newborns. There were positive correlations between EPO and the percentage of hypochromic red blood cells (%HYPOm) and reticulocytes (%HYPOr) [r = 0.45 (p < 0.001) and r = 0.56 (p < 0.001), respectively]. %HYPOm and %HYPOr also had negative correlations with pH [r = -0.53 (p = 0.001) and r = -0.46 (p = 0.001), respectively]. Newborns who had low pH (pH < or =7.15, n = 16) had significantly higher %HYPOm, %HYPOr, and serum transferrin receptor and transferrin concentrations in their cord blood than newborns with normal pH. Thus, in newborn cord blood, the higher number of red cells and reticulocytes with lower Hb content may have impaired the oxygen carrying capacity that has been a trigger for EPO production. Furthermore, signs of lower hemoglobinization of red cells are associated with low umbilical vein pH in the newborns, indicating an increased risk of birth asphyxia.

Propofol and erythropoietin antioxidant properties in rat brain injured tissue

So far, several treatment modalities have been attempted to brain protection in cases such as brain trauma, stroke or brain hemorrhage. However, a treatment method that the effect begins immediately and definitely helpful has not been discovered yet. In this study, we aimed to compare the effects of propofol and erythropoietin (Epo) on brain injury caused by oxidative stress and antioxidant properties of these agents after closed head injury (CHI) in rats. For this study, female Wistar Albino rats were divided into five groups: non-traumatic control group, trauma performed group CHI, trauma with propofol (100 mg/kg) intraperitoneally (i.p.), trauma with Epo (5000 U/kg) i.p. and trauma with propofol and Epo performed study groups. Twenty-four hours after CHI, rats were sacrificed and the brains were removed. Superoxide dismutase (SOD), catalase (CAT), xanthine oxidase (XO), nitric oxide (NO), and malondialdehyde (MDA) levels were measured in brain tissue. MDA and NO levels were decreased significantly in Groups Epo, Propofol and Epo+Propofol than Group CHI (p<0.01). XO activity was significantly lower in Group Epo than Group CHI (p<0.05). Epo and propofol decreased oxidative stress by decreasing MDA and NO level in brain tissue after CHI. However, combination of Epo and propofol has no significant beneficial advantage than Epo or propofol alone.

Erythropoietin attenuates hyperoxia-induced lung injury by down-modulating inflammation in neonatal rats

This study was done to determine whether recombinant human erythropoietin (rhEPO) treatment could attenuate hyperoxia-induced lung injury, and if so, whether this protective effect is mediated by the down-modulation of inflammation in neonatal rats. Newborn Sprague Dawley rat pups were subjected to 14 days of hyperoxia (>95% oxygen) within 10 hr after birth. Treatment with rhEPO significantly attenuated the mortality and reduced body weight gain caused by hyperoxia. With rhEPO treatment, given 3 unit/gm intraperitoneally at 4th, 5th, and 6th postnatal day, hyperoxia- induced alterations in lung pathology such as decreased radial alveolar count, increased mean linear intercept, and fibrosis were significantly improved, and the inflammatory changes such as myeloperoxidase activity and tumor necrosis factor-alpha expression were also significantly attenuated. In summary, rhEPO treatment significantly attenuated hyperoxia-induced lung injury by down-modulating the inflammatory responses in neonatal rats.

Upregulation of erythropoietin receptor in human prostate carcinoma and high-grade prostatic intraepithelial neoplasia

The aim of the present study was to investigate the differential expression of erythropoietin receptor (EPOR) in prostate carcinoma (PCa), high-grade prostatic intraepithelial neoplasia (PIN), prostatic hyperplasia (BPH) lesions and normal prostatic tissues by immunohistochemistry; and to test the hypothesis that upregulation of EPOR is a specific event for prostate carcinogenesis. An immunohistochemical analysis of EPOR was performed on 30 PCa, 50 BPH with/without inflammation lesions and 30 normal prostatic tissue samples. EPOR staining was quantitated and classified into normal expression and overexpression. Totally 16 high-grade PIN lesions were found in this study. Overexpression of EPOR was shown only in PCa and high-grade PIN. Statistical analysis demonstrated that higher median EPOR staining score of PCa and high-grade PIN in comparison with BPH (P < 0.05) and higher median EPOR staining score of PCa compared with high-grade PIN (P < 0.05). Our data demonstrate that upregulation of EPOR is not uncommon for PCa and upregulated EPOR in high-grade PIN suggests upregulation of EPOR is an early event for prostate carcinogenesis. The role of upregulated EPOR and possibly enhanced EPOR signaling in prostate carcinogenesis warrants further studying.

The effect of centrally administered erythropoietin on cardiovascular and respiratory system of anaesthetized rats

Erythropoietin (EPO) is a hematopoietic factor, which is produced primarily by the adult kidney in response to tissue hypoxia. There is strong evidence that EPO may also be synthesized in the brain and act as a neuroprotector or neuromodulator in the central nervous system. The present study investigated the effect of centrally administered EPO on cardiovascular and respiratory parameters in anaesthetized rats. The animals were anaesthetized with ketamine (70 mg/kg) and xylazine (10 mg/kg) mixture. EPO at doses of 0.06, 0.12, 0.25 and 0.50 IU/5 microl or 0.9% saline as a control were injected intracerebroventricularly and blood pressure, heart rate, respiratory rate, tidal volume and minute ventilation were recorded. Following the administration of EPO, there was a significant increase in blood pressure, heart and respiratory rates, tidal volume and minute ventilation which were time and dose dependant. In order to investigate whether these effects of centrally injected EPO was caused by the diffusion of the drug to the periphery, the highest dose EPO (0.5 IU) in the present study, was injected intravenously but intravenously injected EPO showed no significant effect in these parameters. In conclusion, our findings showed that centrally injected erythropoietin caused pressor and tachycardic response, an increase in respiratory frequency and volume in anaesthetized rats. Moreover intravenous injection of the highest dose of EPO used in the study caused no effect suggesting a central mechanism of action for the agent. Hence, one can hypothesize that erythropoietin may play a role in the central regulation of cardiovascular and respiratory system as a neuromodulator or neuromediator.

Anemia and the role of erythropoietin in diabetes

Anemia is more common in patients with diabetes than without diabetes, and the problem is magnified in patients with renal impairment. Diabetic patients with anemia may be at increased risk of adverse outcomes from diabetic retinopathy, nephropathy, neuropathy, and cardiovascular disease. The etiology of anemia in diabetes is multifactorial and includes inflammation, nutritional deficiencies, concomitant autoimmune diseases, drugs, and hormonal changes in addition to kidney disease. Anemia that is associated with erythropoietin deficiency may have prognostic significance for persons with nephropathy or heart failure. In early diabetic nephropathy, damage to the peritubular fibroblasts can occur and lead to erythropoietin deficiency and anemia prior to the loss of filtration. Correction of the anemia not only leads to less fatigue, greater exercise tolerance, and an improved quality of life but also to a reduction in mortality and hospital admissions for congestive heart failure (CHF). Data are accumulating that suggest that treatment of anemia will slow the progression of microvascular and macrovascular complications, including postural hypotension from autonomic neuropathy, retinopathy, and loss of renal function from diabetic nephropathy. Promptly diagnosing and treating anemia in patients with diabetes may result in an improved quality of life and decreased morbidity and mortality.

Erythropoietin and prematurity--where do we stand?

Erythropoietin (EPO) treatment for anemia of prematurity is still controversial. Large multicentric trials demonstrate that administration of EPO+Fe cannot prevent early transfusions, particularly in very low birth weight newborns and in infants with severe neonatal diseases, but may have some beneficial effect to prevent late transfusions. Current treatment of anemia of prematurity should be multifactorial trying to minimize all causes that reduce erthrocytic mass (phlebotomies, use of noninvasive procedures) and promoting all factors that increase it (placental transfusion, adequate nutrition support). To evaluate the real impact of EPO treatment it is mandatory to follow similar transfusion protocols for preterm infants in all the studies. The aim of EPO+Fe administration should be to avoid new late transfusions in very low birth weight preterm infants or to prevent the first transfusion after the second week of life in less immature premature with the objective of reducing the number of donors rather than the number of transfusions. We have limited the use of EPO+Fe to infants <30 weeks gestational age and birth weight <or=1250 g as well as to infants weighing 1250-1500 g with initial severe disease. The comparison of outcomes before (28 months period with EPO+Fe treatment to all premature <or=32 weeks gestational age) and after 20 months of implementation of the new protocol showed a significant decrease in EPO+Fe treatment candidates (40.3% vs. 85.9%, P<0.001) without changes in the percentage of transfusions in both periods. Therefore if EPO treatment is to be given it should be limited to preterm infants with a birth weight <1000 g or those of 1000-1250 g associated with risk factors for blood transfusion. It should be started at 3-7 days of life at doses of 250 U/kg subcutaneously, three times a week, for 4-6 weeks depending on gestational age with oral iron 2-12 mg/kg/day to keep ferritin levels greater than 100 ng/mL.

Retinoic acid and erythropoietin maintain alveolar development in mice treated with an angiogenesis inhibitor

Bronchopulmonary dysplasia in premature infants is characterized by inhibited alveolarization and vasculogenesis. Our goal was to generate a mouse model of inhibited alveolarization by the administration of an inhibitor of angiogenesis. We then examined the effects of retinoic acid (RA) and erythropoietin (EPO) on alveolar development in this model. Three-day-old mice were injected with a single dose of SU1498 (30 mg/kg, subcutaneously) and either concomitant RA (2 mg/kg, intraperitoneally) or EPO (2,000 IU/kg, subcutaneously) for 10 consecutive days, then harvested on Day 21. Morphometric and electron microscopic analysis, and platelet endothelial cell adhesion molecule (PECAM) immunostaining of endothelial cells, were performed on the lung tissue. In vitro assays were also performed to characterize the effects of RA on endothelial cell growth. Alveolar development was attenuated in the SU1498-treated mice, and electron microscopy demonstrated dilated and dysmorphic capillaries in alveolar walls comparable to previous findings in lungs of infants with bronchopulmonary dysplasia. RA or EPO maintained mean alveolar volume, alveolar surface area, and endothelial cell volume density in the SU1498-treated animals. RA also increased the proliferation of human fetal lung capillary endothelial precursor cells in vitro. These results suggest that the maintenance or growth of the endothelial cell population of the distal lung plays a major role in postnatal alveolar development.

Erythropoietin prevents long-term sensorimotor deficits and brain injury following neonatal hypoxia-ischemia in rats

Perinatal asphyxia accounts for behavioral dysfunctions that often manifest as sensorimotor, learning or memory disabilities throughout development and into maturity. Erythropoietin (Epo) has been shown to exert neuroprotective effects in different models of brain injury including experimental models of perinatal asphyxia. However, the effect of Epo on functional abilities following cerebral hypoxia-ischemia (HI) in neonatal rats is not known. The aim of the present study is to investigate the effect of Epo on sensorimotor deficits and brain injury induced by hypoxia-ischemia. Seven-day-old rats underwent unilateral, permanent carotid artery ligation followed by 1 h of hypoxia. Epo was administered as a single dose immediately after the hypoxic insult (2000 U/kg). The neuroprotective effect of Epo was evaluated at postnatal day 42 by using a battery of behavioral tests and histological analysis. The results of the present study suggest that Epo treatment immediately after HI insult significantly facilitated recovery of sensorimotor function. Consistently, histopathological evaluation demonstrated that Epo significantly attenuated brain injury and preserved the integrity of cerebral cortex. These findings indicate that long-term neuroprotective effect of Epo on neonatal HI-induced brain injury might be associated with the preservation of sensorimotor functions.

Erythropoietin is neuroprotective, improves functional recovery, and reduces neuronal apoptosis and inflammation in a rodent model of experimental closed head injury

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in young people in industrialized countries. Although various anti-inflammatory and antiapoptotic modalities have shown neuroprotective effects in experimental models of TBI, to date, no specific pharmacological agent aimed at blocking the progression of secondary brain damage has been approved for clinical use. Erythropoietin (Epo) belongs to the cytokine superfamily and has traditionally been viewed as a hematopoiesis-regulating hormone. The newly discovered neuroprotective properties of Epo lead us to investigate its effect in TBI in a mouse model of closed head injury. Recombinant human erythropoietin (rhEpo) was injected at 1 and 24 h after TBI, and the effect on recovery of motor and cognitive functions, tissue inflammation, axonal degeneration, and apoptosis was evaluated up to 14 days. Motor deficits were lower, cognitive function was restored faster, and less apoptotic neurons and caspase-3 expression were found in rhEpo-treated as compared with vehicle-treated animals (P<0.05). Axons at the trauma area in rhEpo-treated mice were relatively well preserved compared with controls (shown by their density; P<0.01). Immunohistochemical analysis revealed a reduced activation of glial cells by staining for GFAP and complement receptor type 3 (CD11b/CD18) in the injured hemisphere of Epo- vs. vehicle-treated animals. We propose that further studies on Epo in TBI should be conducted in order to consider it as a novel therapy for TBI.

Effects of erythropoietin on hyperoxic lung injury in neonatal rats

Pulmonary oxygen toxicity is believed to play a prominent role in the lung injury that leads to the development of bronchopulmonary dysplasia (BPD). To determine whether human recombinant erythropoietin (rhEPO) treatment reduces the risk of developing BPD, we investigated the effect of rhEPO treatment on the histopathologic changes seen in hyperoxia-induced lung injury of BPD. Twenty-five rat pups were divided into four groups: air-exposed control group (n = 5), hyperoxia-exposed placebo group (n = 7), hyperoxia-exposed rhEPO-treated group (n = 6), and air-exposed rhEPO-treated group (n = 7). Measurement of alveolar surface area, quantification of secondary crest formation, microvessel count, evaluation of alveolar septal fibrosis, and smooth muscle actin immunostaining were performed to assess hyperoxia-induced changes in lung morphology. Treatment of hyperoxia-exposed animals with rhEPO resulted in a significant increase in the mean alveolar area, number of secondary crests formed, and the microvessel count in comparison with hyperoxia-exposed placebo-treated animals. There was significantly less fibrosis in rhEPO-treated animals. However, treatment of hyperoxia-exposed animals with rhEPO did not result in a significant change in smooth muscle content compared with hyperoxia-exposed placebo treated animals. Our results suggest treatment with rhEPO during hyperoxia exposure is associated with improved alveolar structure, enhanced vascularity, and decreased fibrosis. Therefore, we conclude that treatment of preterm infants with EPO might reduce the risk of developing BPD.

Beneficial and ominous aspects of the pleiotropic action of erythropoietin

The primary function of the glycoprotein hormone erythropoietin (Epo) is to promote red cell production by inhibiting apoptosis of erythrocytic progenitors in hemopoietic tissues. However, functional Epo receptors (Epo-R) have recently been demonstrated in various nonhemopoietic tissues indicating that Epo is a more pleiotropic viability and growth factor. Herein, in vitro and in vivo effects of Epo in the brain and the cardiovascular system are reviewed. In addition, the therapeutic impact of Epo in oncology is considered, including the question of whether Epo might promote tumor growth. Convincing evidence is available that Epo acts as a neurotrophic and neuroprotective factor in the brain. Epo prevents neuronal cells from hypoxia-induced and glutamate-induced cell death. Epo-R is expressed by neurons and glia cells in specific regions of the brain. Epo supports the survival of neurons in the ischemic brain. The neuroprotective potential of Epo has already been confirmed in a clinical trial on patients with acute stroke. With respect to the vasculature, Epo acts on both endothelial and smooth muscle cells. Epo promotes angiogenesis and stimulates the production of endothelin and other vasoactive mediators. In addition, Epo-R is expressed by cardiomyocytes. The role of Epo as a myocardial protectant is at the focus of present research. Epo therapy in tumor patients is practiced primarily to maintain the hemoglobin concentration above the transfusion trigger and to reduce fatigue. In addition, increased tumor oxygenation may improve the efficacy of chemotherapy and radiotherapy. However, tumor cells often express Epo-R. Therefore, careful studies are required to fully exclude that recombinant human Epo (rHuEpo) promotes tumor growth.

Molecular biology of erythropoietin

The glycoprotein hormone erythropoietin (EPO) is an essential viability and growth factor for the erythrocytic progenitors. EPO is mainly produced in the kidneys. EPO gene expression is induced by hypoxia-inducible transcription factors (HIF). The principal representative of the HIF-family (HIF-1, -2 and -3) is HIF-1, which is composed of an O2-labile alpha-subunit and a constant nuclear beta-subunit. In normoxia, the alpha-subunit of HIF is inactivated following prolyl- and asparaginyl-hydroxylation by means of alpha-oxoglutarate and Fe(2+)-dependent HIF specific dioxygenases. While HIF-1 and HIF-2 activate the EPO gene, HIF-3, GATA-2 and NFkappaB are likely inhibitors of EPO gene transcription. EPO signalling involves tyrosine phosphorylation of the homodimeric EPO receptor and subsequent activation of intracellular antiapoptotic proteins, kinases and transcription factors. Lack of EPO leads to anemia. Treatment with recombinant human EPO (rHuEPO) is efficient and safe in improving the management of the anemia associated with chronic renal failure. RHuEPO analogues with prolonged survival in circulation have been developed. Whether the recent demonstration of EPO receptors in various non-hemopoietic tissues, including tumor cells, is welcome or ominous still needs to be clarified. Evidence suggests that rHuEPO may be a useful neuroprotective agent.

Age-related changes in erythropoietin immunoreactivity in the cerebral cortex and hippocampus of rats

Although oxidative stress may influence the fluid properties of blood, resulting in a potential decrement in blood flow and oxygen delivery to the brain during aging, very little is known about age-related changes in Epo expression. Therefore, we examined age-related changes in Epo expression in the cerebral cortex and hippocampus with an immunohistochemical technique. In aged rats, there was a significant decrease in Epo immunoreactivity in the pyramidal cells in the cortical regions. In the hippocampus of adult rats, a distinct immunoreactivity pattern was observed in the CA1-3 areas and dentate gyrus. In aged hippocampus, Epo immunoreactivity was significantly deceased in the pyramidal layer of CA1 regions, and the granule cell layer of dentate gyrus. It was noted that there was distinct pattern of Epo immunoreactivity in the pyramidal layer of CA2-CA3 region of aged rats. Epo immunoreactivity was relatively strong, but was observed only in the periphery of the cytoplasm. The first demonstration of age-related decreases in Epo expression in the cerebral cortex and hippocampus may provide useful data for investigating the pathogenesis of age-related neurodegenerative diseases, suggesting that age-related decreases in Epo may contribute to degenerative events following age-related decreases in brain flow and oxygen supply.

Recombinant human erythropoietin for the treatment of renal anaemia in children: no justification for bodyweight-adjusted dosage

BACKGROUND

Drug doses for children are usually calculated by reducing adult doses in proportion to bodyweight. The clinically effective dose of recombinant human erythropoietin (epoetin) in children, however, seems to be higher than predicted by this calculation.

OBJECTIVE

To determine the quantitative relationship between epoetin dose, bodyweight and response in children with end-stage renal disease.

PATIENTS AND METHODS

The time-course of haemoglobin in 52 children during long-term treatment with epoetin beta was analysed by population pharmacodynamic modelling. Patients were 5-20 years old and weighed 16-53kg at the beginning of treatment. Epoetin beta was given intravenously three times per week after haemodialysis. Doses ranged from 110 to 7500IU (3-205 IU/kg). Haemoglobin versus time was described by assuming that the haemoglobin level rises after each dose due to the formation of new red blood cells, which then survive according to a logistic function. The initial rise after each dose was modelled in terms of absolute dose (not dose/kg). A parametric analysis was done with NONMEM, followed by a nonparametric analysis with NPAG.

RESULTS

Dose-response was best described by a sigmoid maximum-effect (E(max)) model with median E(max) = 0.29 g/dL, median 50% effective dose (ED(50)) = 2400IU and shape parameter gamma = 2. The estimated median survival time of the epoetin-induced red blood cells, tau, was 76 days. Neither of the dose-response parameters E(max) and ED(50) showed dependence on bodyweight. The median haemoglobin response to a standard dose, 0.042 g/dL for 1000IU, was similar to that reported for adults with intravenous administration.

CONCLUSIONS

Doses for children in this age range should be specified as absolute amounts rather than amounts per unit bodyweight. Initial doses can be calculated individually, based on haemoglobin level before treatment, the desired haemoglobin at steady state and the median population parameters E(max), ED(50) and tau.

Mechanisms of erythropoietin-induced brain protection in neonatal hypoxia-ischemia rat model

Erythropoietin, a hemotopoietic growth factor, has brain protective actions. This study investigated the mechanisms of Recombinant Human EPO (rhEPO)-induced brain protection in neonates. An established rat hypoxia-ischemia model was used by ligation of the right common carotid artery of 7-day-old pups, followed by 90 minute of hypoxia (8% 02 and 92% N2) at 37 degrees C. Animals were divided into three groups: control, hypoxia-ischemia, and hypoxia-ischemia plus rhEPO treatment. In rhEPO treated pups, 300 units rhEPO was administered intraperitoneally 24 hours before hypoxia. rhEPO treatment (300 units) was administered daily for an additional 2 days. ELISA and immunohistochemistry examined the expression of EPO and EPOR. Brain weight, morphology, TUNEL assay, and DNA laddering evaluated brain protection. rhEPO abolished mortality (from 19% to 0%) during hypoxia insult, increased brain weight from 52% to 88%, reduced DNA fragmentation, and decreased TUNEL-positive cells. Real-time RT-PCR, Western blot, and immunohistochemistry revealed an enhanced expression of heat shock protein 27 (HSP27) in ischemic brain hemisphere. Double labeling of TUNEL with HSP27 showed most HSP27 positive cells were negative to TUNEL staining. rhEPO reduces brain injury, especially apoptotic cell death after neonatal hypoxia-ischemia, partially mediated by the activation of HSP27.

Pediatric tumor cells express erythropoietin and a functional erythropoietin receptor that promotes angiogenesis and tumor cell survival

Erythropoietin was traditionally considered an erythroid-restricted cytokine, but recent evidence indicates a broader role for it in nonhematopoietic tissues, specifically in neural development. Pediatric solid tumors are mostly developmental in origin, and more than 50% of the solid tumors are neural in origin. We found erythropoietin receptor and erythropoietin expression in common pediatric tumor cells: neuroblastomas, Ewing's sarcoma family of tumors, pediatric brain tumors (medulloblastoma, astrocytoma, and ependymoma), Wilms tumors, rhabdomyosarcomas, and hepatoblastomas (n = 24), and in cell lines derived from some of these tumors (n = 25). Expression of erythropoietin in tumor cell lines was hypoxia-inducible. Addition of exogenous erythropoietin to tumor cell lines expressing erythropoietin receptor increased nuclear DNA binding activity of nuclear factor kappa B and increased the expression of the antiapoptotic genes bcl-1, bcl-xL, and mcl-1. Additionally, exogenous erythropoietin increased production and secretion of angiogenic growth factors, vascular endothelial growth factor, or placenta growth factor from the tumor cell lines, which promoted endothelial cell proliferation and chemotaxis. Erythropoietin receptor expression that promotes tumor cell survival and releases angiogenic growth factors in pediatric tumors has not been previously described. Therefore, a careful evaluation of the impact of erythropoietin is warranted in vivo, in xenograft models of pediatric tumors, followed by evaluation in pediatric patients with cancer.

Erythropoietin reduces myocardial infarction and left ventricular functional decline after coronary artery ligation in rats

Erythropoietin (EPO), well known for its role in stimulation of erythropoiesis, has recently been shown to have a dramatic neuroprotective effect in animal models of cerebral ischemia, mechanical trauma of the nervous system, and excitotoxins, mainly by reducing apoptosis. We studied the effect of single systemic administration of recombinant human EPO (rhEPO) on left ventricular (LV) size and function in rats during 8 weeks after the induction of a myocardial infarction (MI) by permanent ligation of the left descending coronary artery. We found that an i.p. injection of 3,000 units/kg of rhEPO immediately after the coronary artery ligation resulted, 24 h later, in a 50% reduction of apoptosis in the myocardial area at risk. Eight weeks after the induction of MI, rats treated with rhEPO had an infarct size 15-25% of the size of that in untreated animals. The reduction in myocardial damage was accompanied by reductions in LV size and functional decline as measured by repeated echocardiography. Thus, a single dose of rhEPO administered around the time of acute, sustained coronary insufficiency merits consideration with respect to its therapeutic potential to limit the extent of resultant MI and contractile dysfunction.

Erythropoietin in the central nervous system, and its use to prevent hypoxic-ischemic brain damage

A new field of clinical and scientific interest has recently developed based on the discovery that the hematopoietic cytokine erythropoietin (Epo) has important non-hematopoietic functions in the brain and other organs, particularly during development. The biological effects of Epo in the central nervous system (CNS) involve activation of its specific receptor and corresponding signal transduction pathways. Epo receptor expression is abundant in the developing mammalian brain, and decreases as term approaches. Epo has been identified as a neurotrophic and neuroprotective agent in a wide variety of experimental paradigms, from neuronal cell culture to in vivo models of brain injury. Several mechanisms by which Epo produces neuroprotection are recognized. Epo (i) decreases glutamate toxicity, (ii) induces the generation of neuronal anti-apoptotic factors, (iii) reduces inflammation, (iv) decreases nitric oxide-mediated injury, and (v) has direct antioxidant effects.

CONCLUSION

Collectively, the evidence suggests that Epo may provide a new approach to the treatment of a variety of CNS disorders in adults and children, especially as a possible therapy for perinatal asphyxia. This review summarizes the current knowledge on the neurotrophic and neuroprotective functions of Epo in the developing and injured brain.

Erythropoietin in human milk: physiology and role in infant health

Human milk contains substantial concentrations of erythropoietin, a hormone best known for its role in the regulation of erythropoiesis. Recent studies show that erythropoietin receptors are widely distributed in human tissues, including the gastrointestinal tract, endothelial cells, spinal cord, and brain, suggesting that erythropoietin plays a wider role in infant development. Mammary epithelial cells contribute to the production of erythropoietin in human milk, and erythropoietin concentrations appear to rise slowly in human milk during the first few months of lactation. Current data suggest that erythropoietin in human milk may play a pleiomorphic role in erythropoiesis, neurodevelopment, maturation of the gut, apoptosis, and immunity in the infant.

Erythropoietin induces changes in gene expression in PC-12 cells

Erythropoietin (EPO) is the primary modulator of red blood cell production. Recently EPO has received considerable attention for its functions outside of hematopoiesis, including its effects in the nervous system where it has been shown to act as a neuroprotectant. To understand the function of EPO in the nervous system and to determine if EPO functions through the same signaling pathways identified in hematopoietic cells, we used cDNA array hybridization and RT-PCR to investigate the changes in gene expression induced by EPO in the neuronal-like PC-12 cell line. PC-12 cells cultured in the presence of EPO (10 U/ml) showed significant changes in gene expression by 3 h with a return to basal expression levels for the vast majority of genes by 24 h. The genes influenced by EPO included genes with known functions in cell proliferation, differentiation and apoptosis. Semi-quantitative RT-PCR confirmed that 24 h pre-treatment with EPO (10 pM) resulted in a 2.5-fold increase in the expression of the anti-apoptotic gene bcl(XL) and a 4-fold decrease in the expression of the pro-apoptotic gene bak. In addition to supporting the current models of EPO function these results suggest previously unidentified mechanisms by which EPO may function in neurons.

Ontogeny of erythropoietin mRNA expression in liver, kidneys and testes of the foetal and the neonatal pig

Erythropoietin (EPO) mRNA expression in kidneys, liver and testes of foetal and neonatal pigs was analysed using a competitive RT-PCR assay. The results indicate that in the foetal pig, erythropoietin expression is greatest in the liver, at birth; hepatic and renal expression are nearly identical, and by 5 weeks of age there is mainly renal expression. The dynamics of the renal expression of EPO mRNA in the perinatal period provide a correlate for observations made earlier of plasma EPO concentrations. Early in foetal life (30 days after artificial insemination), the mesonephroi contained large amounts of EPO mRNA. As in the rat, the testes produced EPO mRNA in amounts comparable to the liver on a per gram tissue basis, though much less on a per organ basis.

Erythropoietin prevents cognition impairment induced by transient brain ischemia in gerbils

Erythropoietin has recently been studied for its role in the central nervous system (CNS). It has been shown to exert neuroprotective effects in different models of brain injury. We studied whether neuroprotective effects assessed from the reduction of neuronal loss after transient brain ischemia are associated to the preservation of learning ability. Recombinant human erythropoietin (0.5-25 U) was injected in the lateral cerebral ventricle of gerbils that are subjected to temporary (3 min) bilateral carotid occlusion. Post-ischemic histological evaluation of CA1 area neuronal loss and passive avoidance test were performed. Treatment with recombinant human erythropoietin significantly reduced delayed neuronal death in the CA1 area of the hippocampus and prevented cognition impairment in the passive avoidance test. These data indicate that recombinant human erythropoietin neuroprotective effects in brain ischemia are associated with the preservation of learning function.