Erythropoietin receptor-mediated inhibition of exocytotic glutamate release confers neuroprotection during chemical ischemia

Emerging therapeutic strategies in hypoxic-ischemic encephalopathy: a focus on cognitive outcomes

Perinatal hypoxia-ischemia represents a significant risk to CNS development, leading to high mortality rates, diverse damages, and persistent neurological deficits. Despite advances in neonatal medicine in recent decades, the incidence of HIE remains substantial. Motor deficits can manifest early, while cognitive impairments may be diagnosed later, emphasizing the need for extended follow-up. This review aims to explore potential candidates for therapeutic interventions for hypoxic-ischemic encephalopathy (HIE), with a focus on cognitive deficits. We searched randomized clinical trials (RCT) that tested drug treatments for HIE and evaluated cognitive outcomes. The results included studies on erythropoietin, melatonin, magnesium sulfate, topiramate, and a combination of vitamin C and ibuprofen. Although there are several indications of the efficacy of these drugs among animal models, considering neuroprotective properties, the RCTs failed to provide complete effectiveness in the context of cognitive impairments derived from HIE. More robust RCTs are still needed to advance our knowledge and to establish standardized treatments for HIE.

Beneficial Effect of Erythropoietin on Ameliorating Propionic Acid-Induced Autistic-Like Features in Young Rats

Autism is a neurodevelopmental disorder that impairs communication and social interaction. This study investigated the possible beneficial effects of erythropoietin (EPO) on experimental autistic-like behaviors induced by propionic acid (PPA). Twenty-four rats were distributed into three groups: (i) control; (ii) PPA_Gp: daily injected subcutaneously with PPA for five consecutive days; PPA+EPO-Gp: injected with PPA, then received intraperitoneal injection of EPO once daily for two weeks. Behavioral changes in the rats were assessed. Specimens from the cerebellar hemispheres were subjected to histological and ultrastructure examination, immunohistochemistry for glial fibrillary acidic protein (GFAP) and calbindin-D28K, and biochemical analysis for glutathione peroxidase (GSH-Px), malondialdehyde (MDA), gamma amino-butyric acid (GABA), and serotonin. PPA-Gp showed significant behavioral impairment, with a significant depletion in GSH-px, GABA, and serotonin and a significant increase in MDA. Histological examination revealed reduced Purkinje cell count with ultrastructural degeneration, irregularly arranged nerve fibers in the molecular layer, astrogliosis, and significantly decreased calbindin-immunostaining compared to the control. EPO protected cerebellar structure, increased Purkinje cell count, improved neuronal morphology, reduced PPA-induced autistic-like features, alleviated neuronal oxidative stress, increased intercellular antioxidant levels, and suppressed inflammation. EPO provided significant protection against PPA-induced autistic features in rats, with structural preservation of Purkinje cells.

Co-occurrence of chronic kidney disease and glaucoma: Epidemiology and etiological mechanisms

As the histology, physiology, and pathophysiology of eyes and kidneys show substantial overlap, it has been suggested that eye and kidney diseases, such as glaucoma and chronic kidney disease (CKD), may be closely interlinked. We review the relationship between CKD and various subtypes of glaucoma, including primary open-angle glaucoma, primary angle- closure glaucoma, normal tension glaucoma, pseudoexfoliation syndrome, and several glaucoma endophenotypes. We also discuss the underlying pathogenic mechanisms and common risk factors for CKD and glaucoma, including atherosclerosis, the renin-angiotensin system, genes and genetic polymorphisms, vitamin D deficiency, and erythropoietin. The prevalence of glaucoma appears elevated in CKD patients, and vice versa, and the literature points to many intriguing associations; however, the associations are not always confirmed, and sometimes apparently opposite observations are reported. Glaucoma and CKD are complex diseases, and their mutual influence is only partially understood.

Recombinant human erythropoietin induces neuroprotection, activates MAPK/CREB pathway, and rescues fear memory after traumatic brain injury with delayed hypoxemia in mice

Therapeutic interventions targeting secondary insults, such as delayed hypoxemia, provide a unique opportunity for treatment in severe traumatic brain injury (TBI). Erythropoietin (EPO) is a hypoxia-responsive cytokine with important roles in neurodevelopment, neuroprotection and neuromodulation. We hypothesized that recombinant human erythropoietin (rhEPO) administration would mitigate injury in a combined injury model of TBI and delayed hypoxemia. Utilizing a clinically relevant murine model of TBI and delayed hypoxemia, we characterized how ongoing rhEPO administration influenced neurogenesis, neuroprotection, synaptic density and, behavioral outcomes early after TBI, and the impact on long-lasting outcomes 6 months after injury. We employed novel object recognition (NOR) and fear conditioning to assess long-term memory. At 1-month post-injury, we observed a significant increase in cued-fear memory response in the rhEPO-injured mice compared with vehicle-injured mice. This was associated with neuroprotection and neurogenesis in the hippocampus and mitogen-activated protein kinase (MAPK)/cAMP response element-binding protein (CREB) signaling activation and increased of excitatory synaptic density in the amygdala. Early rhEPO treatment after injury reduced neurodegeneration and increased excitatory synaptic density in the hippocampus and amygdala at 6 months post-injury. However at 6 months post-injury (4 months after discontinuation of rhEPO), we did not observe changes in behavioral assessments nor MAPK/CREB pathway activation. In summary, these data demonstrate that ongoing rhEPO treatment initiated at a clinically feasible time point improves neurological, cognitive, and histological outcomes after TBI in the setting of secondary hypoxemic insults.

The Potential Role of Hypoxia-Inducible Factor-1 in the Progression and Therapy of Central Nervous System Diseases

Hypoxia-inducible factor-1 (HIF-1) is a heterodimer protein composed of an oxygenregulated functional subunit, HIF-1α, and a structural subunit, HIF-1β, belonging to the basic helixloop- helix family. Strict regulation of HIF-1 protein stability and subsequent transcriptional activity involves various molecular interactions and is primarily controlled by post-transcriptional modifications. Hypoxia, owing to impaired cerebral blood flow, has been implicated in a range of central nervous system (CNS) diseases by exerting a deleterious effect on brain function. As a master oxygen- sensitive transcription regulator, HIF-1 is responsible for upregulating a wide spectrum of target genes involved in glucose metabolism, angiogenesis, and erythropoiesis to generate the adaptive response to avoid, or at least minimize, hypoxic brain injury. However, prolonged, severe oxygen deprivation may directly contribute to the role-conversion of HIF-1, namely, from neuroprotection to the promotion of cell death. Currently, an increasing number of studies support the fact HIF-1 is involved in a variety of CNS-related diseases, such as intracranial atherosclerosis, stroke, and neurodegenerative diseases. This review article chiefly focuses on the effect of HIF-1 on the pathogenesis and mechanism of progression of numerous CNS-related disorders by mediating the expression of various downstream genes and extensive biological functional events and presents robust evidence that HIF-1 may represent a potential therapeutic target for CNS-related diseases.

Erythropoietin improve spatial memory impairment following methamphetamine neurotoxicity by inhibition of apoptosis, oxidative stress and neuroinflammation in CA1 area of hippocampus

OBJECTIVE

Methamphetamine (METH) is one of the most widely used addictive drugs, and addiction to it is on the rise all over the world. METH abuse has long-term damaging effects that reduce memory and impair cognitive functions. According to studies, the observed effects are strongly related to the nerve cell damage caused by METH, which leads to neurotoxicity. Some of these intra-neuronal events include dopamine oxidation, excitotoxicity, and oxidative stress. Erythropoietin (EPO) is a hormone produced primarily by the kidneys and, in small quantities, by the liver. Studies have shown that EPO exhibits considerable neuroprotective effects. This study aimed to investigate the protective effects of EPO on METH neurotoxicity.

METHODS

Initially, 48 male Wistar rats, weighing 250-300 g, were randomly assigned to four groups: control (n = 12), METH (n = 12), and METH+EPO (2500, 5000 IU/kg/IP- n = 12). METH was injected intraperitoneally at a dose of 40 mg per kg of body weight (four injections of 10 mg every two hours) to induce neurotoxicity. EPO was injected at doses of 2500 and 5000 IU/kg seven days after the last METH administration (ip). Morris water maze test was performed following EPO injection (1 day after the last dose) to assess spatial memory. The brains were removed after the behavioral test, biochemical evaluations and immunohistochemistry (caspase-3 and GFAP) was performed.

RESULTS

The results showed that EPO treatment significantly improved spatial memory impairment (P < 0.01), compared to the METH group, EPO was a significant reduction in malondialdehyde and TNF-α (P < 0.01), as well as an increase in superoxide dismutase (P < 0.05) and glutathione-PX (P < 0.01). Furthermore, EPO treatment significantly reduced the number of GFAP positive cells (P < 0.01) and caspase 3 (P < 0.001) in the hippocampus (CA1 region).

CONCLUSIONS

The study findings suggested that EPO may have great neuroprotective effects on METH neurotoxicity due to its anti-inflammatory, antioxidant, and antiapoptotic properties.

Erythropoietin in Optic Neuropathies: Current Future Strategies for Optic Nerve Protection and Repair

Erythropoietin (EPO) is known as a hormone for erythropoiesis in response to anemia and hypoxia. However, the effect of EPO is not only limited to hematopoietic tissue. Several studies have highlighted the neuroprotective function of EPO in extra-hematopoietic tissues, especially the retina. EPO could interact with its heterodimer receptor (EPOR/βcR) to exert its anti-apoptosis, anti-inflammation and anti-oxidation effects in preventing retinal ganglion cells death through different intracellular signaling pathways. In this review, we summarized the available pre-clinical studies of EPO in treating glaucomatous optic neuropathy, optic neuritis, non-arteritic anterior ischemic optic neuropathy and traumatic optic neuropathy. In addition, we explore the future strategies of EPO for optic nerve protection and repair, including advances in EPO derivates, and EPO deliveries. These strategies will lead to a new chapter in the treatment of optic neuropathy.

Does erythropoietin affect the outcome and complication rates of patient with traumatic brain injury? A pooled-analysis

OBJECTIVE

The aim of this meta-analysis was to review the scientific literature published until April 18, 2021, to summarize existing knowledge on the efficacy and safety of erythropoietin (EPO) for traumatic brain injury (TBI).

METHODS

This systematic review followed PRISMA guidelines. Randomized controlled trials (RCTs) reporting on the efficacy and safety of EPO in the treatment of TBI were systematically searched in relevant electronic databases according to a pre-designed search strategy. The primary outcomes are the mortality; and secondary outcomes are the good functional outcome (GFO) and adverse events (AEs).

RESULTS

A total of 10 RCTs involving 2,402 participants fulfilled the inclusion criteria. The results showed that there is a significant difference in terms of the mortality (RR = 0.67, 95% CI = 0.54-0.84, P = 0.0003) and seizure rate (RR = 0.52, 95% CI = 0.29-0.96, P = 0.04) between the EPO groups compared to those in the control groups. However, compared with the control groups, the GFO in the EPO groups was not statistically significant (RR = 1.18, 95% CI = 0.93-1.48, P = 0.17).

CONCLUSIONS

Findings of the present meta-analysis suggest that the use of EPO could reduce mortality rate in patients with TBI, without increasing the incidence of AEs. EPO has potential research and application value in the treatment of TBI.

Genistein protects epilepsy-induced brain injury through regulating the JAK2/STAT3 and Keap1/Nrf2 signaling pathways in the developing rats

BACKGROUND

Epilepsy is a common chronic neurological disease. Recurrent seizures can cause irreversible brain damage. This study aimed to explore the regulation of Genistein on JAK2/STAT3 and Keap1/Nrf2 signaling pathway and the protective effects on brain injury after epilepsy.

METHODS

Pentylenetetrazole (PTZ) was used to induce epilepsy in developing rats and Genistein was used for pretreatment of epilepsy. The seizure latency, grade scores and duration of the first generalized tonic-clonic seizure (GTCs) were recorded. Hippocampus tissue was sampled at 24 h post-epilepsy. Immunofluorescence staining was used to observe mature neurons, activated microglia and astrocytes in the hippocampal CA1 region. Western blot and qRT-PCR were used to determine the protein and mRNA levels of JAK2, STAT3, TNF-α, IL-1β, Keap1, Nrf2, HO-1, NQO1, caspase3, Bax and Bcl2 in the hippocampus.

RESULTS

Immunofluorescence showed that the number of neurons significantly decreased, and activated microglia and astrocytes significantly increased after epilepsy; Western blot and q-PCR showed that the expressions of JAK2, STAT3, TNF-α, IL-1β, Keap1, caspase3 and Bax significantly increased, while Nrf2, HO-1, NQO1 and Bcl-2 were significantly reduced after epilepsy. These effects were reversed by Genistein treatment. Moreover, Genistein was found to prolong seizure latency and reduce seizure intensity score and duration of generalized tonic-clonic seizures(GTCs) CONCLUSIONS: Genistein can activate the Keap1/Nrf2 antioxidant stress pathway and attenuate the activation of microglia and astrocytes. Genistein also inhibits the JAK2-STAT3 inflammation pathway and expression of apoptotic proteins, and increases the number of surviving neurons, thus having a protective effect on epilepsy-induced brain damage.

The Blood-Brain Barrier: Much More Than a Selective Access to the Brain

The blood-brain barrier is a dynamic structure, collectively referred to as the neurovascular unit. It is responsible for the exchange of blood, oxygen, ions, and other molecules between the peripheral circulation and the brain compartment. It is the main entrance to the central nervous system and as such critical for the maintenance of its homeostasis. Dysfunction of the blood-brain barrier is a characteristic of several neurovascular pathologies. Moreover, physiological changes, environmental factors, nutritional habits, and psychological stress can modulate the tightness of the barrier. In this contribution, we summarize our current understanding of structure and function of this important component of the brain. We also describe the neurological deficits associated with its damage. A special emphasis is placed in the effect of the exposure to xenobiotics and pollutants in the permeability of the barrier. Finally, current protective strategies as well as the culture models to study this fascinating structure are discussed.

Experimental Study on the Correlation between miRNA-373 and HIF-1α, MMP-9, and VEGF in the Development of HIE

INTRODUCTION

Microribonucleic acids (miRNAs) have short (approximately 18 to 25) nucleotides and are evolutionarily conserved and endogenously expressed RNAs belonging to a family of noncoding RNA molecules. miRNA-373 regulates cell proliferation, migration, apoptosis, invasion, and repairing damaged DNA after hypoxia stress. Neonatal hypoxic-ischemic encephalopathy (HIE) refers to perinatal asphyxia caused by partial or complete hypoxia, reduced or suspended cerebral blood flow, and fetal or neonatal brain damage. We aim to investigate the relationship between miRNA-373 and HIF-1α, between miRNA-373 MMP-9, and between miRNA-373 VEGF in the occurrence and development of HIE.

METHODS

Human (children) samples were divided into four groups (n = 15 in each group) according to HIE severity. The patient group was divided into middle, moderate, and severe HIE groups. The control group included healthy children or children with nonneurological diseases. The expressions of miRNA-373, HIF-1α, MMP-9, and VEGF were assayed in the serum samples.

RESULTS

Our study showed a strong relationship between miRNA-373 and HIF-1α, between miRNA-373 and MMP-9, and between miRNA-373 and VEGF. The expression levels of miRNA-373, HIF-1α, MMP-9, and VEGF in the HIE groups were much higher than those of the control group.

CONCLUSION

The increased change in miRNA-373 expression has a certain diagnostic significance on neonatal HIE. In the occurrence and development of HIE, miRNA-373 is positively correlated with HIF-1α, MMP-9, and VEGF.

Systematic Review of Erythropoietin (EPO) for Neuroprotection in Human Studies

Erythropoietin (EPO) is an exciting neurotherapeutic option. Despite its potential, concerns exist regarding the potential for thrombosis and adverse events with EPO administration in normonemic adults. Systematic review of literature using PRISMA guidelines to examine the application and risks of EPO as a treatment option for neuroprotection in normonemic adults. Independent, systematic searches were performed in July 2019. PubMed (1960-2019) and the Cochrane Controlled Trials Register (1960-2019) were screened. Search terms included erythropoietin, neuroprotection, and humans. The PubMed search resulted in the following search strategy: ("erythropoietin" [MeSH Terms] OR "erythropoietin" [All Fields] OR "epoetin alfa" [MeSH Terms] OR ("epoetin" [All Fields] AND "alfa" [All Fields]) OR "epoetin alfa" [All Fields]) AND ("neuroprotection" [MeSH Terms] OR "neuroprotection" [All Fields]) AND "humans" [MeSH Terms]. PubMed, Cochrane Controlled Trials Register, and articles based on prior searches yielded 388 citations. 50 studies were included, comprising of 4351 patients. There were 13 studies that noted adverse effects from EPO. Three attributed serious adverse effects to EPO and complications were statistically significant. Two of these studies related the adverse events to the co-administration of EPO with tPA. Minor adverse effects associated with the EPO group included nausea, pyrexia, headache, generalized weakness and superficial phlebitis. Most published studies focus on spinal cord injury, peri-surgical outcomes and central effects of EPO. We found no studies to date evaluating the role of EPO in post-operative pain. Future trials could evaluate this application in persistent post-surgical pain and in the peri-operative period.

Association between chronic kidney disease and Alzheimer's disease: an update

It has been accepted that kidney function is connected with brain activity. In clinical studies, chronic kidney disease (CKD) patients have been found to be prone to suffering cognitive decline and Alzheimer's disease (AD). The cognitive function of CKD patients may improve after kidney transplantation. All these indicators show a possible link between kidney function and dementia. However, little is known about the mechanism behind the relation of CKD and AD. This review discusses the associations between CKD and AD from the perspective of the pathophysiology of the kidney and complications and/or concomitants of CKD that may lead to cognitive decline in the progression of CKD and AD. Potential preventive and therapeutic strategies for AD are also presented. Further studies are warranted in order to confirm whether the setting of CKD is a possible new determinant for cognitive impairment in AD.

Treatment of Neonatal Hypoxic-Ischemic Encephalopathy with Erythropoietin Alone, and Erythropoietin Combined with Hypothermia: History, Current Status, and Future Research

Perinatal hypoxic-ischemic encephalopathy (HIE) remains a major cause of morbidity and mortality. Moderate hypothermia (33.5 °C) is currently the sole established standard treatment. However, there are a large number of infants for whom this therapy is ineffective. This inspired global research to find neuroprotectants to potentiate the effect of moderate hypothermia. Here we examine erythropoietin (EPO) as a prominent candidate. Neonatal animal studies show that immediate, as well as delayed, treatment with EPO post-injury, can be neuroprotective and/or neurorestorative. The observed improvements of EPO therapy were generally not to the level of control uninjured animals, however. This suggested that combining EPO treatment with an adjunct therapeutic strategy should be researched. Treatment with EPO plus hypothermia led to less cerebral palsy in a non-human primate model of perinatal asphyxia, leading to clinical trials. A recent Phase II clinical trial on neonatal infants with HIE reported better 12-month motor outcomes for treatment with EPO plus hypothermia compared to hypothermia alone. Hence, the effectiveness of combined treatment with moderate hypothermia and EPO for neonatal HIE currently looks promising. The outcomes of two current clinical trials on neurological outcomes at 18-24 months-of-age, and at older ages, are now required. Further research on the optimal dose, onset, and duration of treatment with EPO, and critical consideration of the effect of injury severity and of gender, are also required.

The Recombinant Human Erythropoietin Administered in Neonatal Rats After Excitotoxic Damage Induces Molecular Changes in the Hippocampus

In vitro and in vivo experimental evidence has contributed important knowledge regarding the antiapoptotic effect mediated by EPO signaling in the damaged brain, particularly through different models with a hypoxic component. However, little emphasis has been placed on the effectiveness of rhEPO administration against cellular alterations caused by in vivo excitotoxicity or on the molecular mechanism that regulates this effect. In this study, we investigated the effects of a single dose of rhEPO on hippocampal damage induced by subcutaneous application of monosodium glutamate (MSG) on postnatal days 1, 3, 5 and 7 in neonatal rats. We found that a dose of 1000 IU/kg of b.w. administered 24 h after MSG had the greatest protective effect. In addition, we analyzed changes in gene expression, particularly in 3 key molecules involved in EPO-mediated signaling (EPO, EPOR and βcR). We observed that the expression of EPO and EPOR was differentially modified at both the mRNA and protein levels under the evaluated conditions, while the expression of the βcR gene was substantially increased. Our data suggest that a low dose of rhEPO is sufficient to induce cellular protection under these experimental conditions and that the molecular changes could be a positive feedback mechanism, mediated by reactive astrocytes in association with in vivo neuroprotective mechanisms.

Carbamylated Erythropoietin Decreased Proliferation and Neurogenesis in the Subventricular Zone, but Not the Dentate Gyrus, After Irradiation to the Developing Rat Brain

Cranial radiotherapy for pediatric brain tumors causes progressive, debilitating late effects, including cognitive decline. Erythropoietin (EPO) has been shown to be neuroprotective and to promote neuroregeneration. Carbamylated erythropoietin (CEPO) retains the protective properties of EPO but is not erythrogenic. To study the effects of CEPO on the developing brain exposed to radiotherapy, a single irradiation (IR) dose of 6 Gy was administered to the brains of postnatal day 9 (P9) rats, and CEPO (40 μg/kg s.c.) was injected on P8, P9, P11, P13, and P15. To examine proliferation, 5-Bromo-2-deoxyuridine (BrdU) was injected on P15, P16, and P17. CEPO administration did not affect BrdU incorporation in the granule cell layer (GCL) of the hippocampus or in the subventricular zone (SVZ) as quantified 7 days after the last BrdU injection, whereas IR decreased BrdU incorporation in the GCL and SVZ by 63% and 18%, respectively. CEPO did not affect BrdU incorporation in the GCL of irradiated brains, although it was reduced even further (to 31%) in the SVZ. To evaluate the effect of CEPO on neurogenesis, BrdU/doublecortin double-positive cells were quantified. CEPO did not affect neurogenesis in non-irradiated brains, whereas IR decreased neurogenesis by 58% in the dentate gyrus (DG) but did not affect it in the SVZ. In the DG, CEPO did not affect the rate of neurogenesis following IR, whereas in the SVZ, the rate decreased by 30% following IR compared with the rate in vehicle-treated rats. Neither CEPO nor IR changed the number of microglia. In summary, CEPO did not promote neurogenesis in non-irradiated or irradiated rat brains and even aggravated the decreased neurogenesis in the SVZ. This raises concerns regarding the use of EPO-related compounds following radiotherapy.

Synergistic Reduction of Apoptosis With Diazoxide and Erythropoietin in Spinal Cord Ischemic Injury

BACKGROUND

Paraplegia remains a devastating complication of thoracoabdominal aortic intervention. Metabolic stress induces expression of beta common receptor subunit of erythropoietin (EPO) receptor (βcR) to exert a neuroprotective effect in spinal cord ischemia reperfusion injury (SCIR). Diazoxide (DZ) has been shown to induce ischemic tolerance. We previously reported that DZ upregulated βcR expression and enhanced the neuroprotective effects of EPO through the upregulation of βcR. We hypothesize that βcR expression induced by DZ before ischemia amplifies the antiapoptotic effects of EPO in a murine model of SCIR.

METHODS

Experimental groups included phosphate-buffered saline (PBS) pretreatment + PBS immediately before the operation, PBS+EPO, DZ+PBS, DZ+EPO, and sham. Spinal cord ischemia was induced by a 4-minute thoracic aortic cross-clamp. Functional scoring (Basso Mouse Score) was done at 12-hour intervals for 48 hours. Spinal cords were harvested for histologic analysis, and antiapoptotic factors (caspase 3, 8, and 9, B-cell lymphoma-2, and neuroglobin) were evaluated by Western blot analysis.

RESULTS

The motor function of DZ+EPO group was significantly preserved compared with all other groups. The levels of cleaved caspase 8 and 3 in DZ+EPO were significantly lower than in the other groups. Mice treated with DZ+EPO had significantly fewer terminal deoxynucleotide transferase-mediated deoxy uridine triphosphate nick-end labeling-positive cells than other groups.

CONCLUSIONS

Optimized upregulation of βcR by DZ can increase the extrinsic antiapoptotic effects of EPO. Better understanding of this synergetic mechanism may serve to help prevent ischemic complications caused by aortic intervention.

Hypoxia and myelination deficits in the developing brain

Myelination is a complex and orderly process during brain development that is essential for normal motor, cognitive and sensory functions. Cellular and molecular interactions between myelin-forming oligodendrocytes and axons are required for normal myelination in the developing brain. Oligodendrocyte progenitor cells (OPCs) proliferate and differentiate into mature myelin-forming oligodendrocytes. In this connection, astrocytes and microglia are also involved in survival and proliferation of OPCs. Hypoxic insults during the perinatal period affect the normal development, differentiation and maturation of the OPCs or cause their death resulting in impaired myelination. Several factors such as augmented release of proinflammatory cytokines by activated microglia and astrocytes, extracellular accumulation of excess glutamate and increased levels of nitric oxide are some of the underlying factors for hypoxia induced damage to the OPCs. Additionally, hypoxia also leads to down-regulation of several genes involved in oligodendrocyte differentiation encoding proteolipid protein, platelet-derived growth factor receptor and myelin-associated glycoprotein in the developing brain. Furthermore, oligodendrocytes may also accumulate increased amounts of iron in hypoxic conditions that triggers endoplasmic reticulum stress, misfolding of proteins and generation of reactive oxygen species that ultimately would lead to myelination deficits. More in-depth studies to elucidate the pathophysiological mechanisms underlying the inability of oligodendrocytes to myelinate the developing brain in hypoxic insults are desirable to develop new therapeutic options or strategies for myelination deficits.

The long-term effect of erythropoiesis stimulating agents given to preterm infants: a proton magnetic resonance spectroscopy study on neurometabolites in early childhood

BACKGROUND

Erythropoiesis stimulating agents (ESAs) are neuroprotective in cell and animal models of preterm birth. Prematurity has been shown to alter neurometabolite levels in children in studies using proton magnetic resonance spectroscopy (1H-MRS).

OBJECTIVE

We hypothesized that ESA treatment in premature infants would tend to normalize neurometabolites by 4-6 years of age.

MATERIALS AND METHODS

Children in a longitudinal study of neurodevelopment underwent MRI and 1H-MRS at approximately 4 years and 6 years of age. Prematurely born children (500-1,250 g birth weight) received ESAs (erythropoietin or darbepoetin) or placebo during their neonatal hospitalization, and these groups were compared to healthy term controls. 1H-MRS spectra were obtained from the anterior cingulate (gray matter) and frontal lobe white matter, assessing combined N-acetylaspartate and N-acetylaspartylglutamate (tNAA), myo-inositol, choline compounds (Cho), combined creatine and phosphocreatine, and combined glutamate and glutamine.

RESULTS

No significant (P≤0.5) group differences were observed for any metabolite level. Significant age-related increases in white-matter tNAA and Cho were observed, as well as a trend for increased gray-matter tNAA.

CONCLUSION

Neither prematurity nor neonatal ESA treatment was associated with differences in brain metabolite levels in the children of this study at a significance level of 0.05. These findings suggest that earlier differences that might have existed had normalized by 4-6 years of age or were too small to be statistically significant in the current sample.

Understanding the Role of Hypoxia Inducible Factor During Neurodegeneration for New Therapeutics Opportunities

Neurodegeneration (NDG) is linked with the progressive loss of neural function with intellectual and/or motor impairment. Several diseases affecting older individuals, including Alzheimer's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, Parkinson's disease, stroke, Multiple Sclerosis and many others, are the most relevant disorders associated with NDG. Since other pathologies such as refractory epilepsy, brain infections, or hereditary diseases such as "neurodegeneration with brain iron accumulation", also lead to chronic brain inflammation with loss of neural cells, NDG can be said to affect all ages. Owing to an energy and/or oxygen supply imbalance, different signaling mechanisms including MAPK/PI3K-Akt signaling pathways, glutamatergic synapse formation, and/or translocation of phosphatidylserine, might activate some central executing mechanism common to all these pathologies and also related to oxidative stress. Hypoxia inducible factor 1-α (HIF-1α) plays a twofold role through gene activation, in the sense that this factor has to "choose" whether to protect or to kill the affected cells. Most of the afore-mentioned processes follow a protracted course and are accompanied by progressive iron accumulation in the brain. We hypothesize that the neuroprotective effects of iron chelators are acting against the generation of free radicals derived from iron, and also induce sufficient -but not excessive- activation of HIF-1α, so that only the hypoxia-rescue genes will be activated. In this regard, the expression of the erythropoietin receptor in hypoxic/inflammatory neurons could be the cellular "sign" to act upon by the nasal administration of pharmacological doses of Neuro-EPO, inducing not only neuroprotection, but eventually, neurorepair as well.

Electroacupuncture at GV20 and ST36 Exerts Neuroprotective Effects via the EPO-Mediated JAK2/STAT3 Pathway in Cerebral Ischemic Rats

Background

While electroacupuncture (EA) in cerebral ischemia has been used to promote functional recovery, the underlying mechanism of its protective effect remains poorly understood.

Objective

We investigated the effects of EA stimulation at GV20 and ST36 to observe the changes in erythropoietin- (EPO-) mediated Janus family tyrosine kinases 2 (JAK2) signal transducers and activators of the transcription 3 (STAT3) cell pathway.

Methods

Thirty-six specific pathogen-free Sprague-Dawley (SD) male rats were randomly assigned to three groups: the sham-operated group (S group), the middle cerebral artery occlusion (MCAO) group (M group), and the EA group. Neurological deficits were assessed through the Ludmila Belayev 12-score test and 2,3,5-triphenyltetrazolium chloride (TTC) staining was shown. The protein and mRNA expression levels of EPO, the EPO receptor (EpoR), p-JAK2, JAK2, p-STAT3, and STAT3 were examined to explore the EA effect on rats with cerebral ischemic reperfusion injury (CIRI).

Results

EA significantly decreased infarct size and improved neurological function. Furthermore, target EPO, EpoR, JAK2, and STAT3 mRNA and protein levels significantly increased in the EA group.

Conclusions

EA exerts a neuroprotective effect, possibly via the regulation of the EPO-mediated JAK2/STAT3 cell pathway and downstream apoptotic pathways in a rat CIRI model.

Plant-Produced Asialo-Erythropoietin Restores Pancreatic Beta-Cell Function by Suppressing Mammalian Sterile-20-like Kinase (MST1) and Caspase-3 Activation

Pancreatic beta-cell death adversely contributes to the progression of both type I and II diabetes by undermining beta-cell mass and subsequently diminishing endogenous insulin production. Therapeutics to impede or even reverse the apoptosis and dysfunction of beta-cells are urgently needed. Asialo-rhuEPO, an enzymatically desialylated form of recombinant human erythropoietin (rhuEPO), has been shown to have cardioprotective and neuroprotective functions but with no adverse effects like that of sialylated rhuEPO. Heretofore, the anti-apoptotic effect of asialo-rhuEPO on pancreatic beta-cells has not been reported. In the current study, we investigated the cytoprotective properties of plant-produced asialo-rhuEPO (asialo-rhuEPO^P) against staurosporine-induced cell death in the pancreatic beta-cell line RIN-m5F. Our results showed that 60 IU/ml asialo-rhuEPO^P provided 41% cytoprotection while 60 IU/ml rhuEPO yielded no effect. Western blotting results showed that asialo-rhuEPO^P treatment inhibited both MST1 and caspase-3 activation with the retention of PDX1 and insulin levels close to untreated control cells. Our study provides the first evidence indicating that asialo-rhuEPO^P-mediated protection involves the reduction of MST1 activation, which is considered a key mediator of apoptotic signaling in beta-cells. Considering the many advantages its plant-based expression, asialo-rhuEPO^P could be potentially developed as a novel and inexpensive agent to treat or prevent diabetes after further performing studies in cell-based and animal models of diabetes.

Erythropoietin: Endogenous Protection of Ischemic Brain

The human brain requires uninterrupted delivery of blood-borne oxygen and nutrients to sustain its function. Focal ischemia, particularly, ischemic stroke, and global ischemia imposed by cardiac arrest disrupt the brain's fuel supply. The resultant ATP depletion initiates a complex injury cascade encompassing intracellular Ca²⁺ overload, glutamate excitotoxicity, oxido-nitrosative stress, extracellular matrix degradation, and inflammation, culminating in neuronal and astroglial necrosis and apoptosis, neurocognitive deficits, and even death. Unfortunately, brain ischemia has proven refractory to pharmacological intervention. Many promising treatments afforded brain protection in animal models of focal and global ischemia, but failed to improve survival and neurocognitive recovery of stroke and cardiac arrest patients in randomized clinical trials. The culprits are the blood-brain barrier (BBB) that limits transferral of medications to the brain parenchyma, and the sheer complexity of the injury cascade, which presents a daunting array of targets unlikely to respond to monotherapies. Erythropoietin is a powerful neuroprotectant capable of interrupting multiple aspects of the brain injury cascade. Preclinical research demonstrates erythropoietin's ability to suppress glutamate excitotoxicity and intracellular Ca²⁺ overload, dampen oxidative stress and inflammation, interrupt the apoptotic cascade, and preserve BBB integrity. However, the erythropoietin dosages required to traverse the BBB and achieve therapeutically effective concentrations in the brain parenchyma impose untoward side effects. Recent discoveries that hypoxia induces erythropoietin production within the brain and that neurons, astroglia, and cerebrovascular endothelium harbor membrane erythropoietin receptors, raise the exciting prospect of harnessing endogenous erythropoietin to protect the brain from the ravages of ischemia-reperfusion.

Effect of erythropoietin combined with hypothermia on serum tau protein levels and neurodevelopmental outcome in neonates with hypoxic-ischemic encephalopathy

Although hypothermia therapy is effective to treat neonatal hypoxic-ischemic encephalopathy, many neonatal patients die or suffer from severe neurological dysfunction. Erythropoietin is considered one of the most promising neuroprotective agents. We hypothesized that erythropoietin combined with hypothermia will improve efficacy of neonatal hypoxic-ischemic encephalopathy treatment. In this study, 41 neonates with moderate/severe hypoxic-ischemic encephalopathy were randomly divided into a control group (hypothermia alone for 72 hours, n = 20) and erythropoietin group (hypothermia + erythropoietin 200 IU/kg for 10 days, n = 21). Our results show that compared with the control group, serum tau protein levels were lower and neonatal behavioral neurological assessment scores higher in the erythropoietin group at 8 and 12 days. However, neurodevelopmental outcome was similar between the two groups at 9 months of age. These findings suggest that erythropoietin combined with hypothermia reduces serum tau protein levels and improves neonatal behavioral neurology outcome but does not affect long-term neurodevelopmental outcome.

Isoforms of the Erythropoietin receptor in dopaminergic neurons of the Substantia Nigra

Erythropoietin receptor (EpoR) regulates erythrocytes differentiation in blood. In the brain, EpoR has been shown to protect several neuronal cell types from cell death, including the A9 dopaminergic neurons (DA) of the Substantia Nigra (SN). These cells form the nigrostriatal pathway and are devoted to the control of postural reflexes and voluntary movements. Selective degeneration of A9 DA neurons leads to Parkinson's disease. By the use of nanoCAGE, a technology that allows the identification of Transcription Start Sites (TSSs) at a genome-wide level, we have described the promoter-level expression atlas of mouse A9 DA neurons purified with Laser Capture Microdissection (LCM). Here, we identify mRNA variants of the Erythropoietin Receptor (DA-EpoR) transcribed from alternative TSSs. Experimental validation and full-length cDNA cloning is integrated with gene expression analysis in the FANTOM5 database. In DA neurons, the EpoR gene encodes for a N-terminal truncated receptor. Based on STAT5 phosphorylation assays, we show that the new variant of N-terminally truncated EpoR acts as decoy when co-expressed with the full-length form. A similar isoform is also found in human. This work highlights new complexities in the regulation of Erythropoietin (EPO) signaling in the brain.

The Neuroprotective Effect of Erythropoietin on Rotenone-Induced Neurotoxicity in SH-SY5Y Cells Through the Induction of Autophagy

Currently, the autophagy pathway is thought to be important for the pathogenesis of Parkinson's disease (PD), and the modulation of autophagy may be a novel strategy for the treatment of this disease. Erythropoietin (EPO) has been reported to have neuroprotective effects through anti-oxidative, anti-apoptotic, and anti-inflammatory mechanisms, and it has also been shown to modulate autophagy signaling in an oxygen toxicity model. Therefore, we investigated the effects of EPO on autophagy markers and evaluated its neuroprotective effect on rotenone-induced neurotoxicity. We adapted the rotenone-induced neurotoxicity model to SH-SY5Y cells as an in vitro model of PD. We measured cell viability using MTT and annexin V/propidium iodide assays and measured intracellular levels of reactive oxygen species. Immunofluorescence analysis was performed to measure the expression of LC3 and α-synuclein. Intracellular signaling proteins associated with autophagy were examined by immunoblot analysis. EPO mono-treatment increased the levels of mammalian target of rapamycin (mTOR)-independent/upstream autophagy markers, including Beclin-1, AMPK, and ULK-1. Rotenone treatment of SH-SY5Y cells reduced their viability, increased reactive oxygen species levels, and induced apoptosis and α-synuclein expression, and simultaneous exposure to EPO significantly reduced these effects. Rotenone enhanced mTOR expression and suppressed Beclin-1 expression, indicating suppression of the autophagy system. However, combined treatment with EPO restored Beclin-1 expression and decreased mTOR expression. EPO protects against rotenone-induced neurotoxicity in SH-SY5Y cells by enhancing autophagy-related signaling pathways. The experimental evidence for the EPO-induced neuroprotection against rotenone-induced dopaminergic neurotoxicity may significantly impact the development of future PD treatment strategies.

Effect of sex and age interactions on functional outcome after stroke

Stroke is one of the leading causes of death and disability worldwide. Experimental and clinical studies showed that sex and age play an important role in deciding the outcome after stroke. At younger ages, males were shown to have a higher risk for stroke than females. However, this trend reverses in older ages particularly when females reach menopause. Many preclinical studies indicate that steroid hormones modulate the age-dependent differential stroke outcome. In addition, patterns of cell death pathways activated following cerebral ischemia are distinct between males and females, but independent of steroid hormones. Recent studies also indicate that microRNAs play important roles in mediating sex-specific stroke outcome by regulating stroke-related genes. This review discusses the contribution of sex and age to outcome after stroke with particular emphasis on the experimental studies that examined the effects of steroid hormones, differential cell death pathways, and involvement of sex-specific microRNAs following cerebral ischemia. Current understanding of the role of thrombolytic agents in stroke therapy is also discussed.

Neuroprotection in the treatment of glaucoma--A focus on connexin43 gap junction channel blockers

Glaucoma is a form of optic neuropathy and a common cause of blindness, affecting over 60 million people worldwide with an expected rise to 80 million by 2020. Successful treatment is challenging due to the various causes of glaucoma, undetectable symptoms at an early stage and inefficient delivery of drugs to the back of the eye. Conventional glaucoma treatments focus on the reduction of elevated intraocular pressure (IOP) using topical eye drops. However, their efficacy is limited to patients who suffer from high IOP glaucoma and do not address the underlying susceptibility of retinal ganglion cells (RGC) to degeneration. Glaucoma is known as a neurodegenerative disease which starts with RGC death and eventually results in damage of the optic nerve. Neuroprotective strategies therefore offer a novel treatment option for glaucoma by not only preventing neuronal loss but also disease progression. This review firstly gives an overview of the pathophysiology of glaucoma as well as current treatment options including conventional and novel delivery strategies. It then summarizes the rational for neuroprotection as a novel therapy for glaucomatous neuropathies and reviews current potential neuroprotective strategies to preserve RGC, with a focus on connexin43 (Cx43) gap junction channel blockers.

Activity increase in EpoR and Epo expression by intranasal recombinant human erythropoietin (rhEpo) administration in ischemic hippocampi of adult rats

Erythropoietin in the nervous system is a potential neuroprotective factor for cerebral ischemic damage due to specific-binding to the erythropoietin receptor, which is associated with survival mechanisms. However, the role of its receptor is unclear. Thus, this work assessed whether a low dose (500UI/Kg) of intranasal recombinant human erythropoietin administered 3h after ischemia induced changes in the activation of its receptor at the Tyr456-phosphorylated site in ischemic hippocampi in rats. The results showed that recombinant human erythropoietin after injury maintained cell survival and was associated with an increase in receptor phosphorylation at the Tyr456 site as an initial signaling step, which correlated with a neuroprotective effect.

Erythropoietin suppresses the activation of pro-apoptotic genes in head and neck squamous cell carcinoma xenografts exposed to surgical trauma

Background

Several studies on the use of erythropoietin (Epo) to treat anaemia in patients undergoing cancer treatment have shown adverse effects on tumour control and survival. Experimental studies indicate that this could be linked to an interaction with wound healing processes and not an effect on tumour cells per se. We have previously shown that erythropoietin in combination with surgical trauma stimulates tumour growth. In the present study, we investigated the effect of surgery and Epo on gene expression.

Methods

Human tumours from oral squamous cell cancer were xenotransplanted to nude mice treated with Epo. The tumours were then transected in a standardised procedure to mimic surgical trauma and the change in gene expression of the tumours was investigated by microarray analysis. qRT-PCR was used to measure the levels of mRNAs of pro-apoptotic genes. The frequency of apoptosis in the tumours was assessed using immunohistochemistry for caspase-3.

Results

There was little change in the expression of genes involved in tumour growth and angiogenesis but a significant down-regulation of the expression of genes involved in apoptosis. This effect on apoptosis was confirmed by a general decrease in the expression of mRNA for selected pro-apoptotic genes. Epo-treated tumours had a significantly lower frequency of apoptosis as measured by immunohistochemistry for caspase 3.

Conclusions

Our results suggest that the increased tumour growth during erythropoietin treatment might be due to inhibition of apoptosis, an effect that becomes significant during tissue damage such as surgery.

This further suggests that the decreased survival during erythropoietin treatment might be due to inhibition of apoptosis.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-648) contains supplementary material, which is available to authorized users.

Endogenous erythropoietin varies significantly with inflammation-related proteins in extremely premature newborns

INTRODUCTION

Erythropoietin, a pluripotent glycoprotein essential for erythropoiesis, fetal growth, and development, has recently been implicated in innate immune regulation. Data from the ELGAN Study allowed us to evaluate relationships between endogenous erythropoietin and 25 inflammation-related proteins in extremely premature newborns.

METHODS

We measured the concentrations of 25 inflammation-related proteins and of erythropoietin in blood spots collected on postnatal days 1, 7, and 14 from 936 infants born before 28 weeks gestation. We calculated the odds that infants with an inflammation-related protein in the highest quartile for gestational age and collection day had an erythropoietin concentration in the highest or lowest quartile.

RESULTS

The proportion of children with inflammation-associated protein concentrations in the top quartile tended to increase monotonically with increasing quartile of EPO concentrations on 2 of the 3 days assessed. To a large extent, on each of the 3 days assessed, the odds ratios for an erythropoietin concentration in the top quartile were significantly elevated among those with an inflammation-related protein concentration in the top quartile.

CONCLUSIONS

Our findings suggest that in very preterm newborns, circulating levels of endogenous erythropoietin vary significantly with circulating levels of inflammation-related proteins. Elevation of endogenous erythropoietin might not be an epiphenomenon, but instead might contribute to subsequent events, by either promoting or reducing inflammation, or by promoting an anti-injury or repair capability.

Neurodegenerative changes are prevented by Erythropoietin in the pmn model of motoneuron degeneration

Motoneuron diseases are fatal neurodegenerative disorders characterized by a progressive loss of motoneurons, muscle weakness and premature death. The progressive motor neuronopathy (pmn) mutant mouse has been considered a good model for the autosomal recessive childhood form of spinal muscular atrophy (SMA). Here, we investigated the therapeutic potential of Erythropoietin (Epo) on this mutant mouse. Symptomatic or pre-symptomatic treatment with Epo significantly prolongs lifespan by 84.6% or 87.2% respectively. Epo preserves muscle strength and significantly attenuates behavioural motor deficits of mutant pmn mice. Histological and metabolic changes in the spinal cord evaluated by immunohistochemistry, western blot, and high-resolution (1)H-NMR spectroscopy were also greatly prevented by Epo-treatment. Our results illustrate the efficacy of Epo in improving quality of life of mutant pmn mice and open novel therapeutic pathways for motoneuron diseases.

Erythropoietin: powerful protection of ischemic and post-ischemic brain

Ischemic brain injury inflicted by stroke and cardiac arrest ranks among the leading causes of death and long-term disability in the United States. The brain consumes large amounts of metabolic substrates and oxygen to sustain its energy requirements. Consequently, the brain is exquisitely sensitive to interruptions in its blood supply, and suffers irreversible damage after 10-15 min of severe ischemia. Effective treatments to protect the brain from stroke and cardiac arrest have proven elusive, due to the complexities of the injury cascades ignited by ischemia and reperfusion. Although recombinant tissue plasminogen activator and therapeutic hypothermia have proven efficacious for stroke and cardiac arrest, respectively, these treatments are constrained by narrow therapeutic windows, potentially detrimental side-effects and the limited availability of hypothermia equipment. Mounting evidence demonstrates the cytokine hormone erythropoietin (EPO) to be a powerful neuroprotective agent and a potential adjuvant to established therapies. Classically, EPO originating primarily in the kidneys promotes erythrocyte production by suppressing apoptosis of proerythroid progenitors in bone marrow. However, the brain is capable of producing EPO, and EPO's membrane receptors and signaling components also are expressed in neurons and astrocytes. EPO activates signaling cascades that increase the brain's resistance to ischemia-reperfusion stress by stabilizing mitochondrial membranes, limiting formation of reactive oxygen and nitrogen intermediates, and suppressing pro-inflammatory cytokine production and neutrophil infiltration. Collectively, these mechanisms preserve functional brain tissue and, thus, improve neurocognitive recovery from brain ischemia. This article reviews the mechanisms mediating EPO-induced brain protection, critiques the clinical utility of exogenous EPO to preserve brain threatened by ischemic stroke and cardiac arrest, and discusses the prospects for induction of EPO production within the brain by the intermediary metabolite, pyruvate.

Energy-sensitive regulation of Na+/K+-ATPase by Janus kinase 2

Janus kinase 2 (JAK2) contributes to intracellular signaling of leptin and erythropoietin, hormones protecting cells during energy depletion. The present study explores whether JAK2 is activated by energy depletion and regulates Na(+)/K(+)-ATPase, the major energy-consuming pump. In Jurkat cells, JAK2 activity was determined by radioactive kinase assay, phosphorylated JAK2 detected by Western blotting, ATP levels measured by luciferase assay, as well as Na(+)/K(+)-ATPase α1-subunit transcript and protein abundance determined by real-time PCR and Western blotting, respectively. Ouabain-sensitive K(+)-induced currents (Ipump) were measured by whole cell patch clamp. Ipump was further determined by dual-electrode voltage clamp in Xenopus oocytes injected with cRNA-encoding JAK2, active (V617F)JAK2, or inactive (K882E)JAK2. As a result, in Jurkat T cells, JAK2 activity significantly increased following energy depletion by sodium azide (NaN3) or 2,4- dinitro phenol (DNP). DNP- and NaN3-induced decrease of cellular ATP was significantly augmented by JAK2 inhibitor AG490 and blunted by Na(+)/K(+)-ATPase inhibitor ouabain. DNP decreased and AG490 enhanced Ipump as well as Na(+)/K(+)-ATPase α1-subunit transcript and protein abundance. The α1-subunit transcript levels were also enhanced by signal transducer and activator of transcription-5 inhibitor CAS 285986-31-4. In Xenopus oocytes, Ipump was significantly decreased by expression of JAK2 and (V617F)JAK2 but not of (K882E)JAK2, effects again reversed by AG490. In (V617F)JAK2-expressing Xenopus oocytes, neither DNP nor NaN3 resulted in further decline of Ipump. In Xenopus oocytes, the effect of (V617F)JAK2 on Ipump was not prevented by inhibition of transcription with actinomycin. In conclusion, JAK2 is a novel energy-sensing kinase that curtails energy consumption by downregulating Na(+)/K(+)-ATPase expression and activity.

Intranasal formulation of erythropoietin (EPO) showed potent protective activity against amyloid toxicity in the Aβ₂₅₋₃₅ non-transgenic mouse model of Alzheimer's disease

Erythropoietin (EPO) promotes neurogenesis and neuroprotection. We here compared the protection induced by two EPO formulations in a rodent model of Alzheimer's disease (AD): rHu-EPO and a low sialic form, Neuro-EPO. We used the intracerebroventricular administration of aggregated Aβ₂₅₋₃₅ peptide, a non-transgenic AD model. rHu-EPO was tested at 125-500 µg/kg intraperitoneally and Neuro-EPO at 62-250 µg/kg intranasally (IN). Behavioural procedures included spontaneous alternation, passive avoidance, water-maze and object recognition, to address spatial and non-spatial, short- and long-term memories. Biochemical markers of Aβ₂₅₋₃₅ toxicity in the mouse hippocampus were examined and cell loss in the CA1 layer was determined. rHu-EPO and Neuro-EPO led to a significant prevention of Aβ₂₅₋₃₅-induced learning deficits. Both EPO formulations prevented the induction of lipid peroxidation in the hippocampus, showing an antioxidant activity. rHu-EPO (250 µg/kg) or Neuro-EPO (125 µg/kg) prevented the Aβ₂₅₋₃₅-induced increase in Bax level, TNFα and IL-1β production and decrease in Akt activation. A significant prevention of the Aβ₂₅₋₃₅-induced cell loss in CA1 was also observed. EPO is neuroprotective in the Aβ₂₅₋₃₅ AD model, confirming its potential as an endogenous neuroprotection system that could be boosted for therapeutic efficacy. We here identified a new IN formulation of EPO showing high neuroprotective activity. Considering its efficacy, ease and safety, IN Neuro-EPO is a new promising therapeutic agent in AD.

Cytoprotective effect of recombinant human erythropoietin produced in transgenic tobacco plants

Asialo-erythropoietin, a desialylated form of human erythropoietin (EPO) lacking hematopoietic activity, is receiving increased attention because of its broader protective effects in preclinical models of tissue injury. However, attempts to translate its protective effects into clinical practice is hampered by unavailability of suitable expression system and its costly and limit production from expensive mammalian cell-made EPO (rhuEPO(M)) by enzymatic desialylation. In the current study, we took advantage of a plant-based expression system lacking sialylating capacity but possessing an ability to synthesize complex N-glycans to produce cytoprotective recombinant human asialo-rhuEPO. Transgenic tobacco plants expressing asialo-rhuEPO were generated by stably co-expressing human EPO and β1,4-galactosyltransferase (GalT) genes under the control of double CaMV 35S and glyceraldehyde-3-phosphate gene (GapC) promoters, respectively. Plant-produced asialo-rhuEPO (asialo-rhuEPO(P)) was purified by immunoaffinity chromatography. Detailed N-glycan analysis using NSI-FTMS and MS/MS revealed that asialo-rhuEPO(P) bears paucimannosidic, high mannose-type and complex N-glycans. In vitro cytoprotection assays showed that the asialo-rhuEPO(P) (20 U/ml) provides 2-fold better cytoprotection (44%) to neuronal-like mouse neuroblastoma cells from staurosporine-induced cell death than rhuEPO(M) (21%). The cytoprotective effect of the asialo-rhuEPO(P) was found to be mediated by receptor-initiated phosphorylation of Janus kinase 2 (JAK2) and suppression of caspase 3 activation. Altogether, these findings demonstrate that plants are a suitable host for producing cytoprotective rhuEPO derivative. In addition, the general advantages of plant-based expression system can be exploited to address the cost and scalability issues related to its production.

Erythropoietin in Friedreich ataxia

In Friedreich ataxia (FRDA), several candidate substances including erythropoietin (EPO) focus on increase in the amount of frataxin and aim to counteract the consequences of frataxin deficiency. Evidence for recombinant human erythropoietin (rHuEPO) in FRDA is based on in vitro studies using mouse neuronal cell lines, human fibroblasts, cardiomyocytes, and primary lymphocytes from FRDA patients or control subjects which showed a dose-dependent increase of frataxin after incubation with different erythropoietins. The mechanism by which EPO induces frataxin increase remains to be elucidated, but may involve post-transcriptional and/or post-translational modifications of frataxin or alterations in frataxin half-life and metabolism. In vivo data on rHuEPO's ability to increase frataxin in FRDA patients is contradictory as studies on the effect of EPO derivatives in FRDA differ in treatment regimen, sample size, and duration. Open-label studies indicate for sustained frataxin increase, decrease of oxidative stress, and clinical improvement in FRDA patients after administration of rHuEPO. Two randomized controlled studies found acceptable safety and tolerability of EPO derivatives in FRDA. Secondary outcome measures, however, such as frataxin up-regulation and clinical efficacy were not met. This review will focus on (i) pre-clinical work on erythropoietins in FRDA and (ii) clinical studies in FRDA patients exposed to erythropoietins.

Erythropoietin and cytoprotective cytokines in experimental traumatic brain injury

The various biochemical cascades that follow primary brain injury result in secondary brain injury which can adversely affect the clinical outcome. Over the last few years it has been well established that molecules like erythropoietin (Epo) have a neuroprotective role in experimental traumatic brain injury (TBI). Epo is shown to produce this effect by modulating multiple cellular processes, including apoptosis, inflammation, and regulation of cerebral blood flow. Derivatives of Epo, including asialo Epo and carbamylated Epo, have been developed to separate the neuroprotective properties from the erythropoiesis-stimulating activities of Epo which may have adverse effects in clinical situations. Peptides that mimic a portion of the Epo molecule, including Helix B surface peptide and Epotris, have also been developed to isolate the neuroprotective activities. The TBI model in rodents most commonly used to study the effect of Epo and these derivatives in TBI is controlled cortical impact injury, which is a model of focal contusion following a high velocity impact to the parietal cortex. Following TBI, rodents are given Epo or an Epo derivative vs. placebo and the outcome is evaluated in terms of physiological parameters (cerebral blood flow, intracranial pressure, cerebral perfusion pressure), behavioral parameters (motor and memory), and histological parameters (contusion volumes, hippocampus cell counts).

Erythropoietin improves neuronal proliferation in dentate gyrus of hippocampal formation in an animal model of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a prevalent disorder with severe learning and memory defects. Because it has been demonstrated that erythropoietin (EPO) has positive effects on the central nervous system, the aim of this study was to evaluate the effect of EPO on neuronal proliferation in dentate gyrus of hippocampal formation in a well-defined model for AD.

MATERIALS AND METHODS

A rat model of sporadic dementia of Alzheimer's type was established by a bilateral intracerebroventricular injection of streptozotocin (ICV-STZ). Impairment of learning and memory was confirmed 2 weeks after ICV-STZ injection by passive avoidance learning test and then rats were divided into fourgroups:Control, control-EPO, Alzheimer and Alzheimer-EPO. EPO was injected intraperitoneally every other day with a dose of 5000 IU/kg and, finally, the rats were anesthetized and decapitated for immunohistochemical study and neurogenesis investigation (by Ki67 method) in dentate gyrus of hippocampal formation.

RESULTS

The results driven from the histological study showed that EPO significantly increases neuronal proliferation in dentate gyrus of hippocampus in the Alzheimer-EPO group compared with the control, control-EPO and Alzheimer groups; however, there were no differences between the other groups.

CONCLUSION

Our results show that even though EPO in intact animals doesnot change neurogenesis in dentate gyrus, it can nonetheless significantly increase neurogenesis if there is an underlying disorder like neurodegenerative diseases.

Treating patients with schizophrenia deficit with erythropoietin?

This systematic review summarizes and critically appraises the literature on the effect of erythropoietin (EPO) in schizophrenia patients and the pathophysiological mechanisms that may explain the potential of its use in this disease. EPO is mainly known for its regulatory activity in the synthesis of erythrocytes and is frequently used in treatment of chronic anemia. This cytokine, however, has many other properties, some of which may improve the symptoms of psychiatric illness. The review follows the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement guidelines. Three databases (Medline, Web of Science, and Cochrane) were searched combining the search terms 'erythropoietin AND (psychotic disorders OR schizophrenia)'. Seventy-eight studies were included in qualitative synthesis, a meta-analytic approach being prohibited. The findings suggest that several EPO cerebral potential properties may be relevant for schizophrenia treatment, such as neurotransmission regulation, neuroprotection, modulation of inflammation, effects on blood-brain barrier permeability, effects on oxidative stress and neurogenesis. Several potentially detrimental side-effects of EPO therapy, such as increased risk of thrombosis, cancer, increased metabolic rate and mean arterial blood pressure leading to cerebral ischemia could severely limit or halt the use of EPO. Overall, because the available data are inconclusive, further efforts in this field are warranted.

Endogenous erythropoietin from astrocyte protects the oligodendrocyte precursor cell against hypoxic and reoxygenation injury

The hypoxia-responsive cytokine erythropoietin (EPO) provides neuroprotective effects in the damaged brain during ischemic events and neurodegenerative diseases. The purpose of the present study is to evaluate the EPO/EPO receptor (EPOR) endogenous system between astrocyte and oligodendrocyte precursor cell (OPC) under hypoxia. We report here elevated EPO mRNA levels and protein release in cultured astrocytes following hypoxic stimulation by quantitative RT-PCR and ELISA. Furthermore, the EPOR gene expressions were detected in cultured OPCs as in astrocytes and microglias by quantitative RT-PCR. Cell staining revealed the EPOR expression in OPC. To evaluate the protective effect of endogenous EPO from astrocyte to OPCs, EPO/EPOR signaling was blocked by EPO siRNA or EPOR siRNA gene silencing in in vitro study. The suppression of endogenous EPO production in astrocytes by EPO siRNA decreased the protection to OPCs against hypoxic stress. Furthermore, OPC with EPOR siRNA had less cell survival after hypoxic/reoxygenation injury. This suggested that EPO/EPOR signaling from astrocyte to OPC could prevent OPC damage under hypoxic/reoxygenation condition. Our present finding of an interaction between astrocytes and OPCs may lead to a new therapeutic approach to OPCs for use against cellular stress and injury.