Erythropoietin after a century of research: younger than ever

Robust increases in erythropoietin production by the hypoxic fetus is a response to protect the brain and other vital organs

Fetal erythropoietin (EPO), in addition to regulating erythropoiesis, has also tissue-protective properties based on its anti-inflammatory, anti-apoptotic, antioxidant, and neurotrophic effects. Notably, EPO concentrations needed for tissue protection are 100-1000 times higher than concentrations needed for regulating erythropoiesis. This dual effect of EPO is based on EPO-receptor (EPO-R) isoforms, which differ structurally and functionally. We hypothesize in this Integrated Mechanism Review that during severe fetal hypoxia the observed, but poorly understood, marked increases of fetal plasma EPO concentrations occur to protect the brain, heart, and other vital fetal organs. We further hypothesize that the concurrent marked increases of EPO in the amniotic fluid during fetal hypoxia, occur to protect newborn infants from necrotizing enterocolitis. This review presents experimental and clinical evidence in support of these hypotheses and points out unknown or poorly understood functions of EPO in the fetus. If these novel hypotheses are correct, the importance of fetal EPO as an antenatal hypoxia biomarker will become apparent. It will also likely point the way to important diagnostic and therapeutic fetal and neonatal interventions.

The Levels of Hepcidin and Erythropoietin in Pregnant Women with Anemia of Various Geneses

AIM:

The purpose of the present research was to study the content of erythropoietin and hepcidin in serum in pregnant women with iron deficiency anaemia and anaemia of chronic inflammation.

METHODS:

The authors examined 98 pregnant women who were observed in LLP (Regional obstetric-gynaecological centre) in Karaganda. The including criteria for pregnant women in the study was the informed consent of the woman to participate in the study. Exclusion criteria were oncological diseases, HIV-infection, tuberculosis, severe somatic pathology, mental illness, drug addiction. The design of the study was by the legislation of the Republic of Kazakhstan, international ethical norms and normative documents of research organisations, approved by the ethics committee of the Karaganda State Medical University.

RESULTS:

As a result of the study, it was determined that the content of erythropoietin and hepcidin in pregnant women with anemias of different genesis varies ambiguously. In the main group of pregnant women with IDA, the erythropoietin content rises, and the hepcidin level decreases. In pregnant women with ACI, on the contrary, the level of hepcidin increases, and in one subgroup it is significant. However, in pregnant women and with IDA and anemia of chronic inflammation, there is a subgroup of women in whom erythropoietin is either comparable with hepcidin, or their changes are of opposite nature.

CONCLUSION:

The authors concluded that the obtained data indicate ambiguous changes in the level of erythropoietin and hepcidin in pregnant women with anaemias of various origins. In all likelihood, there are still unaccounted factors affecting the content of these protein-regulators of iron metabolism, which require further definition and interpretation in anaemia of pregnant women.

A Randomized Controlled Trial: Regenerative Effects, Efficacy and Safety of Erythropoietin in Burn and Scalding Injuries

In adult’s burn injuries belong to the top 15 causes of injury. Annually more than a million patients receive specialized treatment. Improving burned patients’ outcomes is still a challenge. Effects of erythropoietin (EPO) are reported to be pro-angiogenic, pro-regenerative, anti-inflammatory, immunomodulatory and hypoxia/ischemia protective. Study objectives were to demonstrate cytoprotective and regenerative effects of EPO in burned patients in terms of improved wound healing, reduced morbidity and mortality. This was a prospective, placebo-controlled, randomized, double-blind trial. The trial was conducted in 13 specialized burn care centers in Germany. Adult Patients with 2b° or 3° burn injuries were included. Patients received state of the art burn care including obligatory split skin graft transplantation. Study medication was EPO or placebo every other day for 21 days. Between 12/08 and 06/14, 116 patients were randomized, 84 received study medication (EPO 45, Placebo 39). Primary endpoint analysis revealed inconclusive results, as only a minority of patients reached the primary endpoint [100% re-epithelialization: EPO: 23% (9/40); Placebo 30% (11/37)]. Several secondary endpoints such as SOFA score (morbidity), EPO level in blood and wound healing onset revealed clinical, and statistically significant results in favor of the EPO group. Adverse Events (AEs) and Severe Adverse Events (SAEs) were in expected ranges; AEs EPO: 80%, (36/45), Placebo: 77%, (30/39); SAEs EPO: 24%, (11/45), Placebo: 24%, (8/39). Out of 84 patients two died, one per group, thus mortality was lower than expected. Results (SOFA score) indicate a lower morbidity of the EPO group, suggesting pro-regenerative effects of EPO in burned patients. Higher EPO levels might influence the faster onset of re-epithelialization in the first 10 days of the treatment. Both effects could reveal new therapeutic options.

Clinical Trial Registration: ISRCT Number: ISRCTN95777824 and EudraCT Number: 2006-002886-38, Protocol Number: 0506.

Ventilatory and Autonomic Regulation in Sleep Apnea Syndrome: A Potential Protective Role for Erythropoietin?

Obstructive sleep apnea (OSA) is the most common form of sleep disordered breathing and is associated with wide array of cardiovascular morbidities. It has been proposed that during OSA, the respiratory control center (RCC) is affected by exaggerated afferent signals coming from peripheral/central chemoreceptors which leads to ventilatory instability and may perpetuate apnea generation. Treatments focused on decreasing hyperactivity of peripheral/central chemoreceptors may be useful to improving ventilatory instability in OSA patients. Previous studies indicate that oxidative stress and inflammation are key players in the increased peripheral/central chemoreflex drive associated with OSA. Recent data suggest that erythropoietin (Epo) could also be involved in modulating chemoreflex activity as functional Epo receptors are constitutively expressed in peripheral and central chemoreceptors cells. Additionally, there is some evidence that Epo has anti-oxidant/anti-inflammatory effects. Accordingly, we propose that Epo treatment during OSA may reduce enhanced peripheral/central chemoreflex drive and normalize the activity of the RCC which in turn may help to abrogate ventilatory instability. In this perspective article we discuss the potential beneficial effects of Epo administration on ventilatory regulation in the setting of OSA.

Generation of transgenic chickens expressing the human erythropoietin (hEPO) gene in an oviduct-specific manner: Production of transgenic chicken eggs containing human erythropoietin in egg whites

The transgenic chicken has been considered as a prospective bioreactor for large-scale production of costly pharmaceutical proteins. In the present study, we report successful generation of transgenic hens that lay eggs containing a high concentration of human erythropoietin (hEPO) in the ovalbumin. Using a feline immunodeficiency virus (FIV)-based pseudotyped lentivirus vector enveloped with G glycoproteins of the vesicular stomatitis virus, the replication-defective vector virus carrying the hEPO gene under the control of the chicken ovalbumin promoter was microinjected to the subgerminal cavity of freshly laid chicken eggs (stage X). Stable germline transmission of the hEPO transgene to the G1 progeny, which were non-mosaic and hemizygous for the hEPO gene under the ovalbumin promoter, was confirmed by mating of a G0 rooster with non-transgenic hens. Quantitative analysis of hEPO in the egg whites and in the blood samples taken from G1 transgenic chickens showed 4,810 ~ 6,600 IU/ml (40.1 ~ 55.0 μg/ml) and almost no detectable concentration, respectively, indicating tightly regulated oviduct-specific expression of the hEPO transgene. In terms of biological activity, there was no difference between the recombinant hEPO contained in the transgenic egg white and the commercially available counterpart, in vitro. We suggest that these results imply an important step toward efficient production of human cytokines from a transgenic animal bioreactor.

A genetic variation associated with plasma erythropoietin and a non-coding transcript of PRKAR1A in sickle cell disease

Blood erythropoietin (EPO) increases primarily to hypoxia. In sickle cell anaemia (homozygous HBBE6V; HbSS), plasma EPO is elevated due to hemolytic anaemia-related hypoxia. Hydroxyurea treatment reduces haemolysis and anaemia by increasing foetal haemoglobin, which leads to lower hypoxic transcriptional responses in blood mononuclear cells but paradoxically further increases EPO. To investigate this apparent hypoxia-independent EPO regulation, we assessed two sickle cell disease (SCD) cohorts for genetic associations with plasma EPO, by prioritizing 237,079 quantitative trait loci for expression level and/or transcript isoform variations of 12,727 genes derived from SCD blood mononuclear cells. We found an association between the T allele of SNP rs60684937 and increased plasma EPO (n = 567, combined P = 5.5 × 10 − 8 adjusted for haemoglobin and hydroxyurea) and validated it in independent SCD patients (n = 183, P = 0.018). The T allele of rs60684937 was associated with a relatively increased expression of a non-coding transcript of PRKAR1A (cAMP-dependent protein kinase type I-alpha regulatory subunit) in 58 SCD patients (P = 7.9 × 10 − 7) and 58 HapMap Yoruba samples (P = 0.0011). In conclusion, we demonstrate that plasma EPO elevation with hydroxyurea in SCD is independent of hypoxic responses and that genetic variation at SNP rs60684937 may contribute to EPO regulation through a cAMP-dependent protein kinase A pathway.

Neuroprotective Effects of neuroEPO Using an In Vitro Model of Stroke

Erythropoietin (EPO) is a glycoprotein initially identified as a hormone synthesized and secreted by the kidney that regulates erythropoiesis. EPO, and a group of its derivatives, are being evaluated as possible neuroprotective agents in cerebral ischemia. The objective of this study, using an in vitro model, was to determine how neuroEPO—which is a variant of EPO with a low sialic acid content—protects neurons from the toxic action of glutamate. Primary neuronal cultures were obtained from the forebrains of Wistar rat embryos after 17 days of gestation. Excitotoxicity was induced after nine days of in vitro culture by treatment with a medium containing 100 µM glutamate for 15 min. After this time, a new medium containing 100 ng of neuroEPO/mL was added. Morphological cell change was assessed by phase-contrast microscopy. Oxidative stress was analysed by measuring antioxidant and oxidant activity. After 24 h, the treatment with 100 ng of neuroEPO/mL showed a significant (p < 0.01) decrease in mortality, compared to cells treated with glutamate alone. neuroEPO treatment decreased mortality and tended to reproduce the morphological characteristics of the control. The oxidative stress induced by glutamate is reduced after neuroEPO treatment. These results confirm that neuroEPO has a protective effect against neuronal damage induced by excitotoxicity, improving antioxidant activity in the neuron, and protecting it from oxidative stress.

Erythropoietin Attenuates the Brain Edema Response after Experimental Traumatic Brain Injury

Erythropoietin (EPO) has neuroprotective effects in multiple central nervous system (CNS) injury models; however EPO's effects on traumatic brain edema are elusive. To explore EPO as an intervention in traumatic brain edema, male Sprague–Dawley (SD) rats were subjected to blunt, controlled traumatic brain injury (TBI). Animals were randomized to EPO 5000 IU/kg or saline (control group) intraperitoneally within 30 min after trauma and once daily for 4 consecutive days. Brain MRI, immunohistofluorescence, immunohistochemistry, and quantitative protein analysis were performed at days 1 and 4 post- trauma. EPO significantly prevented the loss of the tight junction protein zona occludens 1 (ZO-1) observed in control animals after trauma. The decrease of ZO-1 in the control group was associated with an immunoglobulin (Ig)G increase in the perilesional parenchyma, indicating blood–brain barrier (BBB) dysfunction and increased permeability. EPO treatment attenuated decrease in apparent diffusion coefficient (ADC) after trauma, suggesting a reduction of cytotoxic edema, and reduced the IgG leakage, indicating that EPO contributed to preserve BBB integrity and attenuated vasogenic edema. Animals treated with EPO demonstrated conserved levels of aquaporin 4 (AQP4) protein expression in the perilesional area, whereas control animals showed a reduction of AQP4. We show that post TBI administration of EPO decreases early cytotoxic brain edema and preserves structural and functional properties of the BBB, leading to attenuation of the vasogenic edema response. The data support that the mechanisms involve preservation of the tight junction protein ZO-1 and the water channel AQP4, and indicate that treatment with EPO may have beneficial effects on the brain edema response following TBI.

NCOR1 modulates erythroid disorders caused by mutations of thyroid hormone receptor α1

Thyroid hormone receptor α (THRA) gene mutations, via dominant negative mode, cause erythroid abnormalities in patients. Using mice expressing a dominant negative TRα1 mutant (TRα1PV; Thra1^PV/+ mice), we showed that TRα1PV acted directly to suppress the expression of key erythroid genes, causing erythroid defects. The nuclear receptor corepressor 1 (NCOR1) was reported to mediate the dominant negative effects of mutated TRα1. However, how NCOR1 could regulate TRα1 mutants in erythroid defects in vivo is not known. In the present study, we crossed Thra1^PV/+ mice with mice expressing a mutant Ncor1 allele (NCOR1ΔID; Ncor1^ΔID mice). TRα1PV mutant cannot bind to NCOR1ΔID. The expression of NCOR1ΔID ameliorated abnormalities in the peripheral blood indices, and corrected the defective differentiation potential of progenitors in the erythroid lineage. The defective terminal erythropoiesis of lineage-negative bone marrow cells of Thra1^PV/+ mice was rescued by the expression of NCOR1ΔID. De-repression of key erythroid genes in Thra1^PV/+Ncor1^ΔID/ΔID mice led to partial rescue of terminal erythroid differentiation. These results indicate that the inability of TRα1PV to recruit NCOR1ΔID to form a repressor complex relieved the deleterious actions of TRα1 mutants in vivo. NCOR1 is a critical novel regulator underpining the pathogenesis of erythroid abnormalities caused by TRα1 mutants.

HIF-prolyl hydroxylases as therapeutic targets in erythropoiesis and iron metabolism

A classic response to systemic hypoxia is the increase in red blood cell production. This response is controlled by the prolyl hydroxylase domain/hypoxia-inducible factor (HIF) pathway, which regulates a broad spectrum of cellular functions. The discovery of this pathway as a key regulator of erythropoiesis has led to the development of small molecules that stimulate the production of endogenous erythropoietin and enhance iron metabolism. This review provides a concise overview of the cellular and molecular mechanisms that govern HIF-induced erythropoietic responses and provides an update on clinical experience with compounds that target HIF-prolyl hydroxylases for anemia therapy.

New options for the anemia of chronic kidney disease

Anemia is a common complication of chronic kidney disease. Use of erythropoiesis-stimulating agents (ESA) has been a mainstay of treatment since 1990. A series of large trials demonstrated that ESAs have serious safety problems, including increasing cardiovascular and thrombotic events, and death. Analyses suggest high pharmacologic doses of ESAs, rather than the highly achieved hemoglobin, may mediate harm. Hypoxia-inducible factor (HIF) activators stimulate endogenous erythropoietin production and enhance iron availability. In early clinical trials, these oral agents appear to be capable of replacing ESA therapy and minimizing the need for i.v. iron therapy for chronic kidney disease–related anemia, while having other potentially advantageous actions. Large phase 3 trials are underway with several HIF activators. This commentary reviews trends in anemia management, the safety issues related to our present therapies, the role of HIF in regulating erythropoiesis, and the diverse actions of HIF activators.

Induction of erythropoietin gene expression in epithelial cells by chemicals identified in GATA inhibitor screenings

Erythropoietin (EPO) is a hormone that promotes proliferation, differentiation and survival of erythroid progenitors. EPO gene expression is regulated in a tissue-specific and hypoxia-inducible manner and is mainly restricted to renal EPO-producing cells after birth. Chronic kidney disease (CKD) confers high risk for renal anemia due to lower EPO production from injured kidneys. In transgenic reporter lines of mice, disruption of a GATA-binding motif within the Epo gene promoter-proximal region restores constitutive reporter expression in epithelial cells. Here, mitoxantrone and its analogues, identified as GATA factor inhibitors through high-throughput chemical library screenings, markedly induce EPO/Epo gene expression in epithelium-derived cell lines and mice regardless of oxygen levels. In contrast, mitoxantrone interferes with hypoxia-induced EPO gene expression in Hep3B cells. Cryptic promoters are created for the EPO/Epo gene expression in epithelial cells upon mitoxantrone treatment, and consequently, unique 5'-untranslated regions are generated. The mitoxantrone-induced aberrant transcripts contribute to the reporter protein production in epithelial cells that carry the reporter gene in the proper reading frame of mouse Epo gene. Thus, EPO production in uninjured adult epithelial cells may be a therapeutic approach for renal anemia in patients with CKD.

Erythropoietin and small molecule agonists of the tissue-protective erythropoietin receptor increase FXN expression in neuronal cells in vitro and in Fxn-deficient KIKO mice in vivo

Friedreich's ataxia (FA) is a progressive neurodegenerative disease caused by reduced levels of the mitochondrial protein frataxin (FXN). Recombinant human erythropoietin (rhEPO) increased FXN protein in vitro and in early clinical studies, while no published reports evaluate rhEPO in animal models of FA. STS-E412 and STS-E424 are novel small molecule agonists of the tissue-protective, but not the erythropoietic EPO receptor. We find that rhEPO, STS-E412 and STS-E424 increase FXN expression in vitro and in vivo. RhEPO, STS-E412 and STS-E424 increase FXN by up to 2-fold in primary human cortical cells and in retinoic-acid differentiated murine P19 cells. In primary human cortical cells, the increase in FXN protein was accompanied by an increase in FXN mRNA, detectable within 4 h. RhEPO and low nanomolar concentrations of STS-E412 and STS-E424 also increase FXN in normal and FA patient-derived PBMC by 20%-40% within 24 h, an effect that was comparable to that by HDAC inhibitor 4b. In vivo, STS-E412 increased Fxn mRNA and protein in wild-type C57BL6/j mice. RhEPO, STS-E412, and STS-E424 increase FXN expression in the heart of FXN-deficient KIKO mice. In contrast, FXN expression in the brains of KIKO mice increased following treatment with STS-E412 and STS-E424, but not following treatment with rhEPO. Unexpectedly, rhEPO-treated KIKO mice developed severe splenomegaly, while no splenomegaly was observed in STS-E412- or STS-E424-treated mice. RhEPO, STS-E412 and STS-E424 upregulate FXN expression in vitro at equal efficacy, however, the effects of the small molecules on FXN expression in the CNS are superior to rhEPO in vivo.

Retinopathy of prematurity: inflammation, choroidal degeneration, and novel promising therapeutic strategies

Retinopathy of prematurity (ROP) is an important cause of childhood blindness globally, and the incidence is rising. The disease is characterized by initial arrested retinal vascularization followed by neovascularization and ensuing retinal detachment causing permanent visual loss. Although neovascularization can be effectively treated via retinal laser ablation, it is unknown which children are at risk of entering this vision-threatening phase of the disease. Laser ablation may itself induce visual field deficits, and there is therefore a need to identify targets for novel and less destructive treatments of ROP. Inflammation is considered a key contributor to the pathogenesis of ROP. A large proportion of preterm infants with ROP will have residual visual loss linked to loss of photoreceptor (PR) and the integrity of the retinal pigment epithelium (RPE) in the macular region. Recent studies using animal models of ROP suggest that choroidal degeneration may be associated with a loss of integrity of the outer retina, a phenomenon so far largely undescribed in ROP pathogenesis. In this review, we highlight inflammatory and neuron-derived factors related to ROP progression, as well, potential targets for new treatment strategies. We also introduce choroidal degeneration as a significant cause of residual visual loss following ROP. We propose that ROP should no longer be considered an inner retinal vasculopathy only, but also a disease of choroidal degeneration affecting both retinal pigment epithelium and photoreceptor integrity.

Erythropoietin and co.: intrinsic structure and functional disorder

Erythropoietin (Epo) is a heavily glycosylated protein, with its main function being related to erythropoiesis, where it controls red blood cell production via interaction with the Epo receptor (EpoR). It also plays a number of important roles in various hormonal, growth factor, and cytokine pathways. These roles are defined by Epo partners, such as the homodimeric (EpoR)2 receptor, the heterodimeric EpoR/βCR receptor and hypoxia inducing factor (HIF). Although the main structural features of both Epo and EpoR are conserved in vertebrates, the secretion sites of Epo in mammals are different from those in other vertebrates. Both biosynthetic and synthetic analogues of this protein are available on the market. Several side effects, such as pure red cells aplaisa, increase the rate of cancer-related death in patients treated with recombinant Epo. The multifunctionality of Epo and the ability of this protein to serve as a hormone, a cytokine, and a growth factor suggest the presence of functional disorder, which is a typical "structural" feature of moonlighting proteins. The goal of this article is to evaluate the roles of intrinsic disorder in the functions of Epo and its primary interactors, EpoR, βCR, and HIF-1α.

EV-3, an endogenous human erythropoietin isoform with distinct functional relevance

Generation of multiple mRNAs by alternative splicing is well known in the group of cytokines and has recently been reported for the human erythropoietin (EPO) gene. Here, we focus on the alternatively spliced EPO transcript characterized by deletion of exon 3 (hEPOΔ3). We show co-regulation of EPO and hEPOΔ3 in human diseased tissue. The expression of hEPOΔ3 in various human samples was low under normal conditions, and distinctly increased in pathological states. Concomitant up-regulation of hEPOΔ3 and EPO in response to hypoxic conditions was also observed in HepG2 cell cultures. Using LC-ESI-MS/MS, we provide first evidence for the existence of hEPOΔ3 derived protein EV-3 in human serum from healthy donors. Contrary to EPO, recombinant EV-3 did not promote early erythroid progenitors in cultures of human CD34+ haematopoietic stem cells. Repeated intraperitoneal administration of EV-3 in mice did not affect the haematocrit. Similar to EPO, EV-3 acted anti-apoptotic in rat hippocampal neurons exposed to oxygen-glucose deprivation. Employing the touch-screen paradigm of long-term visual discrimination learning, we obtained first in vivo evidence of beneficial effects of EV-3 on cognition. This is the first report on the presence of a naturally occurring EPO protein isoform in human serum sharing non-erythropoietic functions with EPO.

Therapeutic targeting of the HIF oxygen-sensing pathway: Lessons learned from clinical studies

The oxygen-sensitive hypoxia-inducible factor (HIF) pathway plays a central role in the control of erythropoiesis and iron metabolism. The discovery of prolyl hydroxylase domain (PHD) proteins as key regulators of HIF activity has led to the development of inhibitory compounds that are now in phase 3 clinical development for the treatment of renal anemia, a condition that is commonly found in patients with advanced chronic kidney disease. This review provides a concise overview of clinical effects associated with pharmacologic PHD inhibition and was written in memory of Professor Lorenz Poellinger.

Renal Anemia Model Mouse Established by Transgenic Rescue with an Erythropoietin Gene Lacking Kidney-Specific Regulatory Elements

The erythropoietin (Epo) gene is under tissue-specific inducible regulation. Because the kidney is the primary EPO-producing tissue in adults, impaired EPO production in chronic kidney disorders results in serious renal anemia. The Epo gene contains a liver-specific enhancer in the 3' region, but the kidney-specific enhancer for gene expression in renal EPO-producing (REP) cells remains elusive. Here, we examined a conserved upstream element for renal Epo regulation (CURE) region that spans 17.4 kb to 3.6 kb upstream of the Epo gene and harbors several phylogenetically conserved elements. We prepared various Epo gene-reporter constructs utilizing a bacterial artificial chromosome and generated a number of transgenic-mouse lines. We observed that deletion of the CURE region (δCURE) abrogated Epo gene expression in REP cells. Although transgenic expression of the δCURE construct rescued Epo-deficient mice from embryonic lethality, the rescued mice had severe EPO-dependent anemia. These mouse lines serve as an elaborate model for the search for erythroid stimulatory activity and are referred to as AnRED (anemic model with renal EPO deficiency) mice. We also dissected the CURE region by exploiting a minigene harboring four phylogenetically conserved elements in reporter transgenic-mouse analyses. Our analyses revealed that Epo gene regulation in REP cells is a complex process that utilizes multiple regulatory influences.

Hypometabolism as the ultimate defence in stress response: how the comparative approach helps understanding of medically relevant questions

First conceptualized from breath-hold diving mammals, later recognized as the ultimate cell autonomous survival strategy in anoxia-tolerant vertebrates and burrowing or hibernating rodents, hypometabolism is typically recruited by resilient organisms to withstand and recover from otherwise life-threatening hazards. Through the coordinated down-regulation of biosynthetic, proliferative and electrogenic expenditures at times when little ATP can be generated, a metabolism turned 'down to the pilot light' allows the re-balancing of energy demand with supply at a greatly suppressed level in response to noxious exogenous stimuli or seasonal endogenous cues. A unifying hallmark of stress-tolerant organisms, the adaptation effectively prevents lethal depletion of ATP, thus delineating a marked contrast with susceptible species. Along with disengaged macromolecular syntheses, attenuated transmembrane ion shuttling and PO₂ -conforming respiration rates, the metabolic slowdown in tolerant species usually culminates in a non-cycling, quiescent phenotype. However, such a reprogramming also occurs in leading human pathophysiologies. Ranging from microbial infections through ischaemia-driven infarcts to solid malignancies, cells involved in these disorders may again invoke hypometabolism to endure conditions non-permissive for growth. At the same time, their reduced activities underlie the frequent development of a general resistance to therapeutic interventions. On the other hand, a controlled induction of hypometabolic and/or hypothermic states by pharmacological means has recently stimulated intense research aimed at improved organ preservation and patient survival in situations requiring acutely administered critical care. The current review article therefore presents an up-to-date survey of concepts and applications of a coordinated and reversibly down-regulated metabolic rate as the ultimate defence in stress responses.

Efficient breathing at neonatal ages: A sex and Epo-dependent issue

During postnatal life, the respiratory control system undergoes intense development and is highly responsive to stimuli emerging from the environment. In fact, interruption of breathing prevents gas exchange and results in systemic hypoxia that, if prolonged, can lead to cardio-respiratory failure or sudden infant death. Moreover, in newborns and infants, respiratory disorders related to neural control dysfunction show significant sexual dimorphism with a higher prevalence in males. To this day, the therapeutic tools available to alleviate these respiratory disorders remain limited. Furthermore, the factors explaining the sexual dimorphism in newborns and during infancy remain unknown. Erythropoietin (Epo) was originally discovered as a cytokine able to increase the production of red blood cells upon conditions of reduced oxygen availability. We now know that Epo is a cytokine also secreted by neurons and astrocytes that protects the brain during trauma or hypoxic stress in a sex dependent manner. In this novel line of research, our previous studies demonstrated at adult ages that cerebral Epo acts as a respiratory stimulant in rodents and humans. These results provided a strong rationale for exploring the role of cerebral Epo in neuronal respiratory control during postnatal development. The objective of this review is to summarize our recent findings showing that cerebral Epo is a potent sex-specific respiratory stimulant at neonatal ages. Keeping in mind that Epo is routinely and safely administrated in newborn humans for anemia and neonatal asphyxia, we predict that our research provides the basis necessary to promote the clinical use of Epo against neonatal respiratory disorders related to neural control dysfunction.

Anti-Inflammatory Effect of Erythropoietin in the TNBS-induced Colitis

Erythropoietin is a potent stimulator of erythroid progenitor cells, which is able to inhibit NF-kB activation, due to its pleiotropic properties, thus promoting an anti-inflammatory effect. As inflammatory bowel disease is a chronic disease with reduced quality of life, and the current pharmacotherapy only induces or maintains the patient in remission, there is a crucial need of new pharmacological approaches. The main objective of this study was to evaluate the effect of erythropoietin in the TNBS-induced colitis model in mice with a normal intestinal flora. Mice with TNBS-induced colitis were treated with a daily dose of erythropoietin at 500 IU/kg bw/day and 1000 IU/Kg bw/day IP during 4 days. As to clinical symptoms/signs, erythropoietin attenuated the decreased body-weight and reduced diarrhoea and oedema of the anus registered in the non-treated mice group in a dose-dependent manner. The anti-inflammatory properties of erythropoietin in the TNBS-induced colitis were confirmed by suppression of pro-inflammatory mediators, such as TNF-α, IL-1β and MPO, as well as a significant increase in the anti-inflammatory cytokine, IL-10, was promoted. These treated mice also presented a reduction in haemoglobin faecal and ALP, suggesting a beneficial effect of erythropoietin in the haemorrhagic focus and destruction of the enterocyte associated with the colon injury induced by TNBS, respectively. The histopathological score was reduced after treatment with erythropoietin, decreasing the severity and extension of the colitis. Furthermore, renal and hepatic biomarkers, as well as haematocrit concentration, remained stabilized after treatment. In conclusion, erythropoietin reduces the inflammatory response associated with TNBS-induced colitis in mice.

Prolyl-4-hydroxylase 2 and 3 coregulate murine erythropoietin in brain pericytes

A classic response to systemic hypoxia is the increased production of red blood cells due to hypoxia-inducible factor (HIF)-mediated induction of erythropoietin (EPO). EPO is a glycoprotein hormone that is essential for normal erythropoiesis and is predominantly synthesized by peritubular renal interstitial fibroblast-like cells, which express cellular markers characteristic of neuronal cells and pericytes. To investigate whether the ability to synthesize EPO is a general functional feature of pericytes, we used conditional gene targeting to examine the von Hippel-Lindau/prolyl-4-hydroxylase domain (PHD)/HIF axis in cell-expressing neural glial antigen 2, a known molecular marker of pericytes in multiple organs. We found that pericytes in the brain synthesized EPO in mice with genetic HIF activation and were capable of responding to systemic hypoxia with the induction of Epo. Using high-resolution multiplex in situ hybridization, we determined that brain pericytes represent an important cellular source of Epo in the hypoxic brain (up to 70% of all Epo-expressing cells). We furthermore determined that Epo transcription in brain pericytes was HIF-2 dependent and cocontrolled by PHD2 and PHD3, oxygen- and 2-oxoglutarate-dependent prolyl-4-hydroxylases that regulate HIF activity. In summary, our studies provide experimental evidence that pericytes in the brain have the ability to function as oxygen sensors and respond to hypoxia with EPO synthesis. Our findings furthermore suggest that the ability to synthesize EPO may represent a functional feature of pericytes in the brain and kidney.

Drug Use and Misuse in the Mountains: A UIAA MedCom Consensus Guide for Medical Professionals

Donegani, Enrico, Peter Paal, Thomas Küpper, Urs Hefti, Buddha Basnyat, Anna Carceller, Pierre Bouzat, Rianne van der Spek, and David Hillebrandt. Drug use and misuse in the mountains: a UIAA MedCom consensus guide for medical professionals. High Alt Med Biol. 17:157-184, 2016.-Aims: The aim of this review is to inform mountaineers about drugs commonly used in mountains. For many years, drugs have been used to enhance performance in mountaineering. It is the UIAA (International Climbing and Mountaineering Federation-Union International des Associations d'Alpinisme) Medcom's duty to protect mountaineers from possible harm caused by uninformed drug use. The UIAA Medcom assessed relevant articles in scientific literature and peer-reviewed studies, trials, observational studies, and case series to provide information for physicians on drugs commonly used in the mountain environment. Recommendations were graded according to criteria set by the American College of Chest Physicians.

RESULTS

Prophylactic, therapeutic, and recreational uses of drugs relevant to mountaineering are presented with an assessment of their risks and benefits.

CONCLUSIONS

If using drugs not regulated by the World Anti-Doping Agency (WADA), individuals have to determine their own personal standards for enjoyment, challenge, acceptable risk, and ethics. No system of drug testing could ever, or should ever, be policed for recreational climbers. Sponsored climbers or those who climb for status need to carefully consider both the medical and ethical implications if using drugs to aid performance. In some countries (e.g., Switzerland and Germany), administrative systems for mountaineering or medication control dictate a specific stance, but for most recreational mountaineers, any rules would be unenforceable and have to be a personal decision, but should take into account the current best evidence for risk, benefit, and sporting ethics.

Systemic endogenous erythropoietin and associated disorders in extremely preterm newborns

OBJECTIVE

To explore the association between concentrations of endogenous erythropoietin (EPO) in blood the first 2 weeks of life and neonatal disorders in extremely low gestational age newborns (ELGANs).

DESIGN

Prospective cohort study.

SETTING

Neonatal care units at 14 participating hospitals in the USA.

PATIENTS

867 children born before the 28th week of gestation from the ELGAN study cohort.

MAIN OUTCOME MEASURES

EPO blood concentrations were measured on postnatal days 1, 7 and 14. The following neonatal characteristics and disorders were registered: blood gases, early and late respiratory dysfunction, pulmonary deterioration, retinopathy of prematurity (ROP), necrotising enterocolitis (NEC) and bronchopulmonary dysplasia (BPD). We calculated the gestational age-adjusted ORs for having each disorder associated with an EPO blood concentration in the highest or lowest quartile, compared with infants whose EPO concentration was in the middle two quartiles on the corresponding day.

RESULTS

Newborns whose day-1 EPO was in the highest quartile were at increased risk for early and persistent respiratory dysfunction during the first 2 weeks of life, and NEC requiring surgery. The lowest EPO quartile on day 1 was associated with a decreased risk of moderate BPD. The association between low EPO and decreased risk of respiratory complications persisted on day 7. On day 14, being in the highest EPO quartile was associated with increased risk of ROP, and BPD not requiring ventilation assistance.

CONCLUSIONS

EPO blood concentrations in extremely preterm newborns during the first 2 weeks of life convey information about increased risks of bowel, lung and retinal diseases.

Carbamylated erythropoietin enhances mice ventilatory responses to changes in O2 but not CO2 levels

Erythropoietin (EPO) has beneficial tissue-protective effects in several diseases but erythrocytosis may cause deleterious effects in EPO-treated patients. Thus carbamylated-EPO (C-EPO) and other derivatives retaining tissue-protective but lacking bone marrow-stimulating actions have been developed. Although EPO modulates ventilatory responses, the effects of C-EPO on ventilation have not been investigated. Here, basal breathing and respiratory chemoreflexes were measured by plethysmography after acute and chronic treatments with recombinant human C-EPO (rhC-EPO; 15,000 IU/kg during 5days) or saline (control group). Hematocrit, plasma and brainstem rhC-EPO levels were also quantified. Chronic rhC-EPO significantly elevated tissue rhC-EPO levels but not hematocrit. None of the drug regimen altered basal ventilation (normoxia). Chronic but not acute rhC-EPO enhanced hyperoxic ventilatory depression, and sustained the hypoxic ventilatory response mainly via a reduction of the roll-off phase. By contrast, rhC-EPO did not blunt the ventilatory response to hypercapnia. Thus, chronic C-EPO may be a promising therapy to improve breathing during hypoxia while minimizing adverse effects on cardiovascular function.

Nickel in equine sports drug testing - pilot study results on urinary nickel concentrations

RATIONALE

The issue of illicit performance enhancement spans human and animal sport in presumably equal measure, with prohibited substances and methods of doping conveying both ways. Due to the proven capability of unbound ionic cobalt (Co(2) (+) ) to stimulate erythropoiesis in humans, both human and equine anti-doping regulations have listed cobalt as a banned substance, and in particular in horse drug testing, thresholds for cobalt concentrations applying to plasma and urine have been suggested or established. Recent reports about the finding of substantial amounts of undeclared nickel in arguably licit performance- and recovery-supporting products raised the question whether the ionic species of this transition metal (Ni(2) (+) ), which exhibits similar prolyl hydroxylase inhibiting properties to Co(2) (+) , has been considered as a substitute for cobalt in doping regimens.

METHODS

Therefore, a pilot study with 200 routine post-competition doping control horse urine samples collected from animals participating in equestrian, gallop, and trotting in Europe was conducted to provide a first dataset on equine urinary Ni(2) (+) concentrations. All specimens were analyzed by conventional inductively coupled plasma mass spectrometry (ICP-MS) to yield quantitative data for soluble nickel.

RESULTS

Concentrations ranging from below the assay's limit of quantification (LOQ, 0.5 ng/mL) up to 33.4 ng/mL with a mean value (± standard deviation) of 6.1 (±5.1) ng/mL were determined for the total nickel content.

CONCLUSIONS

In horses, nickel is considered a micronutrient and feed supplements containing nickel are available; hence, follow-up studies are deemed warranted to consolidate potential future threshold levels concerning urine and blood nickel concentrations in horses using larger sets of samples for both matrices and to provide in-depth insights by conducting elimination studies with soluble Ni(2) (+) -salt species. Copyright © 2016 John Wiley & Sons, Ltd.

Carbamylated Erythropoietin Outperforms Erythropoietin in the Treatment of AKI-on-CKD and Other AKI Models

Erythropoietin (EPO) may be a beneficial tissue-protective cytokine. However, high doses of EPO are associate with adverse effects, including thrombosis, tumor growth, and hypertension. Carbamylated erythropoietin (CEPO) lacks both erythropoietic and vasoconstrictive actions. In this study, we compared the renoprotective, hemodynamic, and hematologic activities and survival effects of identical EPO and CEPO doses in rat models of clinically relevant AKI presentations, including ischemia-reperfusion-induced AKI superimposed on CKD (5000 U/kg EPO or CEPO; three subcutaneous injections) and ischemia-reperfusion-induced AKI in old versus young animals and male versus female animals (1000 U/kg EPO or CEPO; three subcutaneous injections). Compared with EPO therapy, CEPO therapy induced greater improvements in renal function and body weight in AKI on CKD animals, with smaller increases in hematocrit levels and similarly improved survival. Compared with EPO therapy in the other AKI groups, CEPO therapy induced greater improvements in protection and recovery of renal function and survival, with smaller increases in systolic BP and hematocrit levels. Overall, old or male animals had more severe loss in kidney function and higher mortality rates than young or female animals, respectively. Notably, mRNA and protein expression analyses confirmed the renal expression of the heterodimeric EPO receptor/CD131 complex, which is required for the tissue-protective effects of CEPO signaling. In conclusion, CEPO improves renal function, body and kidney weight, and survival in AKI models without raising hematocrit levels and BP as substantially as EPO. Thus, CEPO therapy may be superior to EPO in improving outcomes in common forms of clinical AKI.

Lung Structure and the Intrinsic Challenges of Gas Exchange

Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints.

Efficacy and Safety of Erythropoietin to Prevent Acute Kidney Injury in Patients With Critical Illness or Perioperative Care: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Objective:

The aim was to investigate the efficacy and safety of erythropoietin (EPO) to prevent acute kidney injury (AKI) in patients with critical illness or perioperative care.

Methods:

Randomized controlled trials comparing EPO with placebo for AKI prevention in adult patients with critical illness or perioperative care were searched in MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Web of Science, and Clinical Trials.gov until October 2014. The outcomes of interest included the incidence of AKI, dialysis requirement, mortality, and adverse event. Fixed effect model was used to calculate the pooled risk ratio (RR) and 95% confidence interval (CI) for eligible studies.

Results:

Ten randomized controlled trials involving 2759 participants were identified and included in the analysis. Compared with placebo, EPO administration did not reduce the incidence of AKI (RR, 0.97; 95% CI, 0.79–1.19; P = 0.782), dialysis requirement (RR, 0.72; 95% CI, 0.31–1.70; P = 0.457), or mortality (RR, 0.96; 95% CI, 0.78–1.18; P = 0.705). Moreover, EPO had no effect on the risk of adverse events, but estimations of RR were difficult due to their relatively infrequent occurrence.

Conclusions:

This meta-analysis suggests that prophylactic administration of EPO in patients with critical illness or perioperative care does not prevent AKI, dialysis requirement, or mortality.

Diverse of Erythropoiesis Responding to Hypoxia and Low Environmental Temperature in Vertebrates

Erythrocytes are responsible for transporting oxygen to tissue and are essential for the survival of almost all vertebrate animals. Circulating erythrocyte counts are tightly regulated and respond to erythrocyte mass and oxygen tension. Since the discovery of erythropoietin, the erythropoietic responses to environment and tissue oxygen tension have been investigated in mice and human. Moreover, it has recently become increasingly clear that various environmental stresses could induce the erythropoiesis via various modulating systems, while all vertebrates live in various environments and habitually adapt to environmental stress. Therefore, it is considered that investigations of erythropoiesis in vertebrates provide a lead to the various erythropoietic responses to environmental stress. This paper comparatively introduces the present understanding of erythropoiesis in vertebrates. Indeed, there is a wide range of variations in vertebrates' erythropoiesis. This paper also focused on erythropoietic responses to environmental stress, hypoxia, and lowered temperature in vertebrates.

Quick preparation of nanoluciferase-based tracers for novel bioluminescent receptor-binding assays of protein hormones: Using erythropoietin as a model

Nanoluciferase (NanoLuc) is a newly developed small luciferase reporter with the so far brightest bioluminescence. In recent studies, we developed NanoLuc as an ultrasensitive probe for novel bioluminescent receptor-binding assays of some protein/peptide hormones. In the present study, we proposed a simple method for quick preparation of the NanoLuc-based protein tracers using erythropoietin (Epo) as a model. Epo is a glycosylated cytokine that promotes erythropoiesis by binding and activating the cell membrane receptor EpoR. For quick preparation of a bioluminescent Epo tracer, an Epo-Luc fusion protein carrying a NanoLuc-6 × His-tag at the C-terminus was secretorily overexpressed in transiently transfected human embryonic kidney (HEK) 293 T cells. The Epo-Luc fusion protein retained high-binding affinities with EpoR either overexpressed in HEK293T cells or endogenously expressed in mouse erythroleukemia cells, representing a novel ultrasensitive bioluminescent tracer for non-radioactive receptor-binding assays. Sufficient Epo-Luc tracer for thousands of assays could be quickly obtained within 2 days through simple transient transfection. Thus, our present work provided a simple method for quick preparation of novel NanoLuc-based bioluminescent tracers for Epo and some other protein hormones to facilitate their ligand-receptor interaction studies.

Roles of renal erythropoietin-producing (REP) cells in the maintenance of systemic oxygen homeostasis

Erythropoietic induction is critical for enhancing the efficiency of oxygen delivery during the chronic phase of the systemic hypoxia response. The erythroid growth factor erythropoietin (Epo) triggers the erythropoietic induction through the activation of erythroid genes related to cell survival, differentiation, and iron metabolism. Because Epo is produced in renal Epo-producing (REP) cells in a hypoxia-inducible manner, REP cells serve as a control center for the systemic hypoxia response. In fact, the loss of Epo production in REP cells causes chronic severe anemia in genetically modified mice, and REP cell-specific inactivation of PHD2 (prolyl-hydroxylase domain enzyme 2) results in erythrocytosis via overexpression of the Epo gene due to the constitutive activation of HIF2α (hypoxia-inducible transcription factor 2α). REP cells are located in the interstitial spaces between renal tubules and capillaries, where the oxygen supply is low but oxygen consumption is high, for the highly sensitive detection of decreased oxygen supplies to the body. Under disease conditions, REP cells transform to myofibroblasts and lose their Epo-producing ability. Therefore, elucidation of Epo gene regulation and REP cell features directly contributes to understanding the pathology of chronic kidney disease. To further analyze REP cells, we introduce a newly established mouse line in which REP cells are efficiently labeled with fluorescent protein.

Widespread Expression of Erythropoietin Receptor in Brain and Its Induction by Injury

Erythropoietin (EPO) exerts potent neuroprotective, neuroregenerative and procognitive functions. However, unequivocal demonstration of erythropoietin receptor (EPOR) expression in brain cells has remained difficult since previously available anti-EPOR antibodies (EPOR-AB) were unspecific. We report here a new, highly specific, polyclonal rabbit EPOR-AB directed against different epitopes in the cytoplasmic tail of human and murine EPOR and its characterization by mass spectrometric analysis of immuno-precipitated endogenous EPOR, Western blotting, immunostaining and flow cytometry. Among others, we applied genetic strategies including overexpression, Lentivirus-mediated conditional knockout of EpoR and tagged proteins, both on cultured cells and tissue sections, as well as intracortical implantation of EPOR-transduced cells to verify specificity. We show examples of EPOR expression in neurons, oligodendroglia, astrocytes and microglia. Employing this new EPOR-AB with double-labeling strategies, we demonstrate membrane expression of EPOR as well as its localization in intracellular compartments such as the Golgi apparatus. Moreover, we show injury-induced expression of EPOR. In mice, a stereotactically applied stab wound to the motor cortex leads to distinct EpoR expression by reactive GFAP-expressing cells in the lesion vicinity. In a patient suffering from epilepsy, neurons and oligodendrocytes of the hippocampus strongly express EPOR. To conclude, this new analytical tool will allow neuroscientists to pinpoint EPOR expression in cells of the nervous system and to better understand its role in healthy conditions, including brain development, as well as under pathological circumstances, such as upregulation upon distress and injury.

Probing protease sensitivity of recombinant human erythropoietin reveals α3-α4 inter-helical loop as a stability determinant

Although unglycosylated HuEpo is fully functional, it has very short serum half-life. However, the mechanism of in vivo clearance of human Epo (HuEpo) remains largely unknown. In this study, the relative importance of protease-sensitive sites of recombinant HuEpo (rHuEpo) has been investigated by analysis of structural data coupled with in vivo half-life measurements. Our results identify α3-α4 inter-helical loop region as a target site of lysosomal protease Cathepsin L. Consistent with previously-reported lysosomal degradation of HuEpo, these results for the first time identify cleavage sites of rHuEpo by specific lysosomal proteases. Furthermore, in agreement with the lowered exposure of the peptide backbone around the cleavage site, remarkably substitutions of residues with bulkier amino acids result in significantly improved in vivo stability. Together, these results have implications for the mechanism of in vivo clearance of the protein in humans.

Anaemia in kidney disease: harnessing hypoxia responses for therapy

Improved understanding of the oxygen-dependent regulation of erythropoiesis has provided new insights into the pathogenesis of anaemia associated with renal failure and has led to the development of novel therapeutic agents for its treatment. Hypoxia-inducible factor (HIF)-2 is a key regulator of erythropoiesis and iron metabolism. HIF-2 is activated by hypoxic conditions and controls the production of erythropoietin by renal peritubular interstitial fibroblast-like cells and hepatocytes. In anaemia associated with renal disease, erythropoiesis is suppressed due to inadequate erythropoietin production in the kidney, inflammation and iron deficiency; however, pharmacologic agents that activate the HIF axis could provide a physiologic approach to the treatment of renal anaemia by mimicking hypoxia responses that coordinate erythropoiesis with iron metabolism. This Review discusses the functional inter-relationships between erythropoietin, iron and inflammatory mediators under physiologic conditions and in relation to the pathogenesis of renal anaemia, as well as recent insights into the molecular and cellular basis of erythropoietin production in the kidney. It furthermore provides a detailed overview of current clinical experience with pharmacologic activators of HIF signalling as a novel comprehensive and physiologic approach to the treatment of anaemia.

Endogenous brain erythropoietin is a potent sex-specific respiratory stimulant in adult and newborn mice

We tested the hypothesis that endogenous brain Epo is a respiratory stimulant. Adult (3 mo) and newborn (10 days) male and female mice received an intracisternal (cisterna magna) injection of soluble Epo receptor (sEpoR; competes with EpoR to bind Epo; 50 μg/ml) or vehicle (0.1% BSA in PBS). Twenty-four hours after injection, we used whole body plethysmography to record minute ventilation (V̇e) tidal volume (VT), respiratory frequency (fR), O2 consumption (V̇o2), and CO2 production (V̇co2) under normoxia and progressive exposure to hypoxia (12-10-6% O2; 10 min each). In adult male and female mice sEpoR decreased normoxic V̇e (-25%), due to a decrease of VT in males and fR in females. Moreover, sEpoR injection decreased the ventilatory response to 12% O2, assessed as V̇e/V̇o2 or V̇e/V̇co2, in male but not in female mice. In newborn male and female mice sEpoR decreased V̇e (-37% in males, -59% in females) and VT (-38% in males, -47% in females) in normoxia and fR in females. During hypoxia, sEpoR decreased V̇e/V̇o2 and V̇e/V̇co2 in mice of both sexes. Upon extreme hypoxia (6% O2), the newborn mice treated with sEpoR showed respiratory depression, signs of asphyxia (gasping) and a high mortality rate in males and females. We concluded that endogenous brain Epo is a potent respiratory stimulant under normoxia and hypoxia in adult and newborn mice. Because sex-specific effects are different in newborn male and female, sex steroids secreted at different ages mice appear to modulate the effects of Epo on respiratory regulation in normoxia and in response to hypoxia.

Generation of transgenic fibroblasts producing doxycycline-inducible human interferon-α or erythropoietin for a bovine mammary bioreactor

Interferon α (IFN-α) is a cytokine, produced predominantly in immune cells in response to pathogens, which interferes with viral replication in host cells. Another cytokine hormone, erythropoietin (EPO), is synthesized in interstitial fibroblasts of the kidney and acts as a stimulator for the production of red blood cells. Importantly, the two cytokines have been used in the treatment of certain hematological malignancies, including renal anemia. In the production of recombinant proteins, a transgenic expression system in bovine species is an efficient strategy for pharmaceutical production. In the present study, recombinant constructs capable of producing recombinant human IFN-α and EPO proteins were established and were generated containing the mammary gland-specific αS1-casein promoter region (between -175 and + 796 nt), as this promoter was revealed to have the highest level of activity in a previous promoter study. In order to minimize developmental toxicity by constitutive exogenous expression, a doxycycline (dox)-inducible system was introduced to the IFN-α/EPO-expressing constructs. Therefore, a unitary tetracycline (tet)-on the IFN-α/EPO vector was established, which combined a tet-on activator cassette controlled by the αS1-casein promoter, with a responder cassette encoding the IFN-α/EPO gene, controlled by the tetracycline response element (TRE) promoter. In these systems, the tet-controlled transactivator is affected by mammary gland-specific αS1-casein promoter, and binding of the transcriptional activator to the TRE results in transcription of the downstream IFN-α/EPO genes in the presence of dox. To assess this, the unitary tet-on IFN-α/EPO vector was introduced into a bovine mammary gland cell line (MAC-T), and the cells were then treated with 0.1-1 µg/ml dox. A marked increase was observed in the expression levels of IFN-α/EPO. In addition, bovine transgenic fibroblasts containing a mammary gland-specific and dox-inducible IFN-α/EPO construct were generated. These transgenic fibroblasts may provide a source for somatic cell nuclear transfer for the generation of transgenic cattle producing recombinant human IFN-α/EPO protein during lactation.

High-dose erythropoietin for tissue protection

BACKGROUND

The discovery of potential anti-apoptotic and cytoprotective effects of recombinant human erythropoietin (rHuEPO) has led to clinical trials investigating the use of high-dose, short-term rHuEPO therapy for tissue protection in conditions such as stroke and myocardial infarction. Experimental studies have been favourable, but the clinical efficacy has yet to be validated.

MATERIALS AND METHODS

We have reviewed clinical studies regarding the use of high-dose, short-term rHuEPO therapy for tissue protection in humans with the purpose to detail the safety and efficacy of rHuEPO for this indication. A systematic literature search was performed using the PubMed/MEDLINE database for randomized, placebo-controlled clinical trials.

RESULTS

Twenty-six randomized controlled trials that enrolled 3176 patients were included. The majority of trials (20 trials including 2724 patients) reported no effect of rHuEPO therapy on measures of tissue protection. Five trials including 1025 patients reported safety concerns in the form of increased mortality or adverse event rates. No studies reported reduced mortality.

CONCLUSIONS

Evidence is sparse to support a tissue-protective benefit of rHuEPO in humans. Moreover, a number of studies indicate that short-term administration of high-dose rHuEPO is associated with an increased risk of mortality and serious adverse events. Further work is needed to elucidate the mechanisms of toxicity of rHuEPO in humans.

Recombinant erythropoietin in humans has a prolonged effect on circulating erythropoietin isoform distribution

The membrane-assisted isoform immunoassay (MAIIA) quantitates erythropoietin (EPO) isoforms as percentages of migrated isoforms (PMI). We evaluated the effect of recombinant human EPO (rhEPO) on the distribution of EPO isoforms in plasma in a randomized, placebo-controlled, double-blinded, cross-over study. 16 healthy subjects received either low-dose Epoetin beta (5000 IU on days 1, 3, 5, 7, 9, 11 and 13); high-dose Epoetin beta (30.000 IU on days 1, 2 and 3 and placebo on days 5, 7, 9, 11 and 13); or placebo on all days. PMI on days 4, 11 and 25 was determined by interaction of N-acetyl glucosamine with the glycosylation dependent desorption of EPO isoforms. At day 25, plasma-EPO in both rhEPO groups had returned to values not different from the placebo group. PMI with placebo, reflecting the endogenous EPO isoforms, averaged 82.5 (10.3) % (mean (SD)). High-dose Epoetin beta decreased PMI on days 4 and 11 to 31.0 (4.2)% (p<0.00001) and 45.2 (7.3)% (p<0.00001). Low-dose Epoetin beta decreased PMI on days 4 and 11 to 46.0 (12.8)% (p<0.00001) and 46.1 (10.4)% (p<0.00001). In both rhEPO groups, PMI on day 25 was still decreased (high-dose Epoetin beta: 72.9 (19.4)% (p = 0.029); low-dose Epoetin beta: 73.1 (17.8)% (p = 0.039)). In conclusion, Epoetin beta leaves a footprint in the plasma-EPO isoform pattern. MAIIA can detect changes in EPO isoform distribution up til at least three weeks after administration of Epoetin beta even though the total EPO concentration has returned to normal.

Glucose, insulin, and oxygen interplay in placental hypervascularisation in diabetes mellitus

The placental vasculature rapidly expands during the course of pregnancy in order to sustain the growing needs of the fetus. Angiogenesis and vascular growth are stimulated and regulated by a variety of growth factors expressed in the placenta or present in the fetal circulation. Like in tumors, hypoxia is a major regulator of angiogenesis because of its ability to stimulate expression of various proangiogenic factors. Chronic fetal hypoxia is often found in pregnancies complicated by maternal diabetes as a result of fetal hyperglycaemia and hyperinsulinemia. Both are associated with altered levels of hormones, growth factors, and proinflammatory cytokines, which may act in a proangiogenic manner and, hence, affect placental angiogenesis and vascular development. Indeed, the placenta in diabetes is characterized by hypervascularisation, demonstrating high placental plasticity in response to diabetic metabolic derangements. This review describes the major regulators of placental angiogenesis and how the diabetic environment in utero alters their expression. In the light of hypervascularized diabetic placenta, the focus was placed on proangiogenic factors.

Effectiveness of treatment of iron deficiency anemia in rats with squid ink melanin-Fe

Iron deficiency anemia (IDA) is the one of the most common nutritional problems and is encountered all over the world. This study analysed the effects of squid ink melanin-Fe (SM-Fe) on IDA in rats. Forty weanling SD male rats were used and thirty-two rats were fed an iron-deficient diet for 4 weeks. Then SM-Fe (dosages of iron is 6 mg kg(-1) BW) was given to the IDA rats once a day for 3 weeks by intragastric administration, with FeCl3 and FeSO4 (dosages of iron is 6 mg kg(-1) BW) as positive controls. While the IDA model group and the control group were administrated distilled deionized water each day for 3 weeks. The content of haemoglobin (Hb), serum iron (SI), total iron binding capacity (TIBC), serum ferritin (SF), transferrin receptor (sTfR), erythropoietin (EPO), and iron content in the liver and spleen were measured. The results showed that the content of Hb, SI, SF, EPO, iron content in the liver and spleen were significantly increased in the iron supplement groups (SM-Fe, FeCl3 and FeSO4) compared with the model group (P < 0.05), while TIBC and sTfR were significantly decreased in the iron supplement groups compared with the model group (P < 0.05). In comparison with the FeCl3 and FeSO4 groups, a higher bioavailability of iron and fewer side effects were observed in the SM-Fe group. The present study indicated that SM-Fe is an effective source of iron supplement for IDA rats and might be exploited as a new iron fortifier.