Non-erythropoietic Derivatives Research Articles

Erythropoietin and Non-Erythropoietic Derivatives in Cognition.

Cognitive deficits are widespread in psychiatric disorders, including major depression and schizophrenia. These deficits are known to contribute significantly to the accompanying functional impairment. Progress in the development of targeted treatments of cognitive deficits has been limited and there exists a major unmet need to develop more efficacious treatments. Erythropoietin (Epo) has shown promising procognitive effects in psychiatric disorders, providing support for a neurotrophic drug development approach. Several preclinical studies with non-erythropoietic derivatives have demonstrated that the modulation of behavior is independent of erythropoiesis. In this review, we examine the molecular, cellular and cognitive actions of Epo and non-erythropoietic molecular derivatives by focusing on their neurotrophic, synaptic, myelin plasticity, anti-inflammatory and neurogenic mechanisms in the brain. We also discuss the role of receptor signaling in Epo and non-erythropoietic EPO-mimetic molecules in their procognitive effects.

Perioperative administration of high-dose recombinant human erythropoietin for delayed graft function prevention in kidney transplantation: a meta-analysis.

Delayed graft function (DGF) due to ischemia-reperfusion injury is a major early complication of kidney transplantation (KT). Recombinant human erythropoietin (rHuEPO) has been shown to exert nephroprotective action in animal models. We conducted a meta-analysis to explore the impact of rHuEPO on DGF in KT. Eligible studies comparing perioperative high-dose rHuEPO with placebo or no therapy for prevention of DGF were identified through MEDLINE, CENTRAL, and Transplant Library. Their design and data were assessed by two independent reviewers. Among 737 examined studies, four randomized controlled trials, involving 356 recipients of kidney allografts from deceased donors, fulfilled inclusion criteria. Statistical heterogeneity across studies was not significant (P = 0.98, I(2) = 0%). In a random effects model, no significant difference was found in the occurrence of DGF (odds ratio: 0,74, 95% CI: 0.47-1.18, P = 0.21). At 4 weeks after KT, the rHuEPO group exhibited higher systolic blood pressure (mean difference: 6.47 mmHg, 95% CI: 1.25-11.68, P = 0.02). Perioperative, high-dose rHuEPO administration does not prevent DGF in deceased donor KT. Furthermore, it is associated with higher systolic blood pressure leading to safety concerns. Nonerythropoietic rHuEPO derivatives, designed for nephroprotective action without increasing cardiovascular risk, might prove an alternative but still are at early stages of development.

Erythropoietin, but not the correction of anemia alone, protects from chronic kidney allograft injury

Anemia can contribute to chronic allograft injury by limiting oxygen delivery to tissues, particularly in the tubulointerstitium. To determine mechanisms by which erythropoietin (EPO) prevents chronic allograft injury we utilized a rat model of full MHC-mismatched kidney transplantation (Wistar Furth donor and Lewis recipients) with removal of the native kidneys. EPO treatment entirely corrected post-transplant anemia. Control rats developed progressive proteinuria and graft dysfunction, tubulointerstitial damage, inflammatory cell infiltration, and glomerulosclerosis, all prevented by EPO. Normalization of post-transplant hemoglobin levels by blood transfusions, however, had no impact on chronic allograft injury, indicating that EPO-mediated graft protection went beyond the correction of anemia. Compared to syngeneic grafts, control allografts had loss of peritubular capillaries, higher tubular apoptosis, tubular and glomerular oxidative injury, and reduced expression of podocyte nephrin; all prevented by EPO treatment. The effects of EPO were associated with preservation of intragraft expression of angiogenic factors, upregulation of the anti-apoptotic factor p-Akt in tubuli, and increased expression of Bcl-2. Inhibition of p-Akt by Wortmannin partially antagonized the effect of EPO on allograft injury and tubular apoptosis, and prevented EPO-induced Bcl-2 upregulation. Thus non-erythropoietic derivatives of EPO may be useful to prevent chronic renal allograft injury.

Bench-to-bedside review: Erythropoietin and its derivatives as therapies in critical care

Erythropoietin (EPO) is known to have numerous biological functions. Its primary function in the body is to increase red blood cell numbers by way of preventing the apoptosis of erythroid progenitor cells via the homodimeric EPO receptor. The discovery that the local production of EPO within the brain in response to hypoxia or ischemia protects neurons against injury via an anti-apoptotic effect formed the basis of the hypothesis that the local generation of EPO limits the extent of injury. Although the hypothesis proved to be true in pre-clinical models of ischemia/reperfusion injury and inflammation, the randomized, controlled clinical trials that followed demonstrated serious adverse events of EPO due to activation of the hematopoietic system. Consequently, derivatives of EPO that lacked erythropoietic activity were discovered to reduce injury in many pre-clinical models associated with ischemia and inflammation. Unfortunately, there are no published clinical trials to determine the efficacy of non-erythropoietic derivatives of EPO in humans.

The Use of Erythropoietin and its Derivatives to Treat Spinal Cord Injury

Spinal Cord Injury (SCI) is a complex process which leads to destruction of neuronal tissue and also vascular structure. After SCI many potentially toxic substances are activated and released into the injury site causing secondary degeneration. Erythropoietin (EPO) is a possible therapeutic strategy to treat SCI. Over the last decade attention has been focused on the molecular mechanisms underlying its neuroprotective effects. A major concern expressed by clinicians is that besides its protective effects, EPO also demonstrates hematopoietic activity and increases the risk for thrombosis after the administration of multiple doses of this glycoprotein. Recently, tissue protective functions of EPO have been separated from its hematopoietic actions leading to the development of EPO derivatives and mimetics. Neuroscientists are focusing on recombinant human EPO (rhEPO) and its non-erythropoietic derivatives, investigating their anti-apoptotic potential and anti-inflammatory function as well as their role in restoring vascular integrity. Carbamylated erythropoietin (CEPO) and asialo erythropoietin (AsialoEPO) are structural derivatives of EPO that have no effect on erythrocyte mass whereas they retained its neuroprotective effects. In this review article, we provide a short overview of the animal studies on rhEPO and its derivatives in experimental models of SCI. Both the efficacy and the safety profile of EPO-structural and functional variants are still to be demonstrated in patients. Further clinical studies should reveal whether derivatives and variants of erythropoietin provide any benefits over the use of rhEPO in the treatment of spinal cord injury observed in the experimental studies.

Promises and Pitfalls in Erythopoietin-Mediated Tissue Protection: Are Nonerythropoietic Derivatives a Way Forward?

Promises and Pitfalls in Erythopoietin-Mediated Tissue Protection: Are Nonerythropoietic Derivatives a Way Forward?

Carbamylated erythropoietin increases frataxin independent from the erythropoietin receptor

Friedreich's ataxia (FRDA) is a neurodegenerative disorder caused by decreased expression of the mitochondrial protein frataxin. Recently we showed in a clinical pilot study in Friedreich's ataxia patients that recombinant human erythropoietin (rhuEPO) significantly increases frataxin-expression. In this in vitro study, we investigated the role of the erythropoietin receptor (EPO-R) in the frataxin increasing effect of rhuEPO and if nonerythropoietic carbamylated erythropoietin (CEPO), which cannot bind to the classical EPO-R increases frataxin expression. In our experiments human erythroleukaemic K562 cells (+ EPO-R), human monocytic leukemia THP-1 cells (- EPO-R) and isolated primary lymphocytes from healthy control and FRDA patients were incubated with different concentrations of rhuEPO or CEPO. Frataxin-expression was detected by an electrochemical luminescence immunoassay (based on the principle of an ELISA). We show that rhuEPO increases frataxin-expression in K562 cells (expressing EPO-R) as well as in THP-1 cells (without EPO-R expression). These results were confirmed by the finding that CEPO, which cannot bind to the classical EPO-R increased frataxin expression in the same concentration range as rhuEPO. In addition, we show that both EPO derivatives significantly increase frataxin-expression in vitro in control and Friedreich's ataxia patients primary lymphocytes. Our results provide a scientific basis for further studies examining the effectiveness of nonerythropoietic derivatives of erythropoietin for the treatment of Friedreich's ataxia patients.

443. AAV-Mediated Gene Supply of Non-Erythropoietic Erythropoietin Derivatives Improves Photoreceptor Morphology and Function in Models of Retinal Degenerative Diseases

443. AAV-Mediated Gene Supply of Non-Erythropoietic Erythropoietin Derivatives Improves Photoreceptor Morphology and Function in Models of Retinal Degenerative Diseases

Reduced Functional Deficits, Neuroinflammation, and Secondary Tissue Damage after Treatment of Stroke by Nonerythropoietic Erythropoietin Derivatives

Carbamylerythropoietin (CEPO) does not bind to the classical erythropoietin (EPO) receptor. Nevertheless, similarly to EPO, CEPO promotes neuroprotection on the histologic level in short-term stroke models. In the present study, we investigated whether CEPO and other nonerythropoietic EPO analogs could enhance functional recovery and promote long-term histologic protection after experimental focal cerebral ischemia. Rats were treated with the compounds after focal cerebral ischemia. Animals survived 1, 7, or 60 days and underwent behavioral testing (sensorimotor and foot-fault tests). Brain sections were stained and analyzed for Iba-1, myeloperoxidase, Tau-1, CD68 (ED1), glial fibrillary acidic protein (GFAP), Fluoro-Jade B staining, and overall infarct volumes. Treatment with CEPO reduced perifocal microglial activation (P<0.05), polymorphomonuclear cell infiltration (P<0.05), and white matter damage (P<0.01) at 1 day after occlusion. Carbamylerythropoietin-treated rats showed better functional recovery relative to vehicle-treated animals as assessed 1, 7, 14, 28, and 50 days after stroke. Both GFAP and CD68 were decreased within the ipsilateral thalamus of CEPO-treated animals 60 days postoperatively (P<0.01 and P<0.05, respectively). Furthermore, behavioral analysis showed efficacy of CEPO treatment even if administered 24 h after the stroke. Other nonerythropoietic derivatives such as carbamylated darbepoetin alfa and the mutant EPO-S100E were also found to protect against ischemic damage and to improve postischemic neurologic function. In conclusion, these results show that postischemic intravenous treatment with nonerythropoietic EPO derivatives leads to improved functional recovery, which may be linked to their long-term effects against neuroinflammation and secondary tissue damage.

Amelioration of spinal cord compressive injury by pharmacological preconditioning with erythropoietin and a nonerythropoietic erythropoietin derivative

Spinal cord injury (SCI) is a devastating clinical syndrome for which no truly efficacious therapy has yet been identified. In preclinical studies, erythropoietin (EPO) and its nonerythropoietic derivatives asialoEPO and carbamylated EPO have markedly improved functional outcome when administered after compressive SCI. However, an optimum treatment paradigm is currently unknown. Because the uninjured spinal cord expresses a high density of EPO receptor (EPOR) in the basal state, signaling through these existing receptors in advance of injury (pharmacological preconditioning) might confer neuroprotection and therefore be potentially useful in situations of anticipated damage. The authors compared asialoEPO, a molecule that binds to the EPOR with high affinity but with a brief serum half-life (t1/2 < 2 minutes), to EPO to determine whether a single dose (10 microg/kg of body weight) administered by intravenous injection 24 hours before 1 minute of spinal cord compression provides benefit as determined by a 6-week assessment of neurological outcome and by histopathological analysis. Rats pretreated with asialoEPO or EPO and then subjected to a compressive injury exhibited improved motor function over 42 days, compared with animals treated with saline solution. However, pretreatment efficacy was substantially poorer than efficacy of treatment initiated at the time of injury. Serum samples drawn immediately before compression confirmed that no detectable asialoEPO remained within the systemic circulation. Western blot and immunohistochemical analyses performed using uninjured spinal cord 24 hours after a dose of asialoEPO exhibited a marked increase in glial fibrillary acidic protein, suggesting a glial response to EPO administration. These results demonstrate that EPO and its analog do not need to be present at the time of injury to provide tissue protection and that tissue protection is markedly effective when either agent is administered immediately after injury. Furthermore, the findings suggest that asialoEPO is a useful reagent with which to study the dynamics of EPO-mediated neuroprotection. In addition, the findings support the concept of using a nonerythropoietic EPO derivative to provide tissue protection without activating the undesirable effects of EPO.

Delayed administration of erythropoietin and its non-erythropoietic derivatives ameliorates chronic murine autoimmune encephalomyelitis

Erythropoietin (EPO) mediates a wide range of neuroprotective activities, including amelioration of disease and neuroinflammation in rat models of EAE. However, optimum dosing parameters are currently unknown. In the present study, we used a chronic EAE model induced in mice by immunization with the myelin oligodendrocyte glycoprotein peptide (MOG 35–55) to compare the effect of EPO given with different treatment schedules. EPO was administered intraperitoneally at 0.5, 5.0 or 50 μg/kg three times weekly starting from day 3 after immunization (preventive schedule), at the onset of clinical disease (therapeutic schedule) or 15 days after the onset of symptoms (late therapeutic schedule). The results show that EPO is effective even when given after the appearance of clinical signs of EAE, but with a reduced efficacy compared to the preventative schedule. To determine whether this effect requires the homodimeric EPO receptor (EPOR 2)-mediated hematopoietic effect of EPO, we studied the effect of carbamylated EPO (CEPO) that does not bind EPOR 2. CEPO, ameliorated EAE without changing the hemoglobin concentration. Another non-erythropoietic derivative, asialoEPO was also effective. Both EPO and CEPO equivalently decreased the EAE-associated production of TNF-α, IL-1β and IL-1Ra in the spinal cord, and IFN-γ by peripheral lymphocytes, indicating that their action involves targeting neuroinflammation. The lowest dosage tested appeared fully effective. The possibility to dissociate the anti-neuroinflammatory action of EPO from its hematopoietic action, which may cause undesired side effects in non-anemic patients, present new avenues to the therapy of multiple sclerosis.

Emerging biological roles for erythropoietin in the nervous system

Erythropoietin mediates an evolutionarily conserved, ancient immune response that limits damage to the heart, the nervous system and other tissues following injury. New evidence indicates that erythropoietin specifically prevents the destruction of viable tissue surrounding the site of an injury by signalling through a non-haematopoietic receptor. Engineered derivatives of erythropoietin that have a high affinity for this receptor have been developed, and these show robust tissue-protective effects in diverse preclinical models without stimulating erythropoiesis. A recent successful proof-of-concept clinical trial that used erythropoietin to treat human patients who had suffered a stroke encourages the evaluation of both this cytokine and non-erythropoietic derivatives as therapeutic agents to limit tissue injury.

A nonerythropoietic derivative of erythropoietin protects the myocardium from ischemia-reperfusion injury.

The cytokine erythropoietin (EPO) protects the heart from ischemic injury, in part by preventing apoptosis. However, EPO administration can also raise the hemoglobin concentration, which, by increasing oxygen delivery, confounds assignment of cause and effect. The availability of EPO analogs that do not bind to the dimeric EPO receptor and lack erythropoietic activity, e.g., carbamylated EPO (CEPO), provides an opportunity to determine whether EPO possesses direct cardioprotective activity. In vivo, cardiomyocyte loss after experimental myocardial infarction (MI) of rats (40 min of occlusion with reperfusion) was reduced from approximately 57% in MI-control to approximately 45% in animals that were administered CEPO daily for 1 week (50 microg/kg of body weight s.c.) with the first dose administered intravenously 5 min before reperfusion. CEPO did not increase the hematocrit, yet it prevented increases in left ventricular (LV) end-diastolic pressure, reduced LV wall stress in systole and diastole, and improved LV response to dobutamine infusion compared with vehicle-treated animals. In agreement with the cardioprotective effect observed in vivo, staurosporine-induced apoptosis of adult rat or mouse cardiomyocytes in vitro was also significantly attenuated ( approximately 35%) by CEPO, which is comparable with the effect of EPO. These data indicate that prevention of cardiomyocyte apoptosis, in the absence of an increase in hemoglobin concentration, explains EPO's cardioprotection. Nonerythropoietic derivatives such as CEPO, devoid of the undesirable effects of EPO, e.g., thrombogenesis, could represent safer and more effective alternatives for treatment of cardiovascular diseases, such as MI and heart failure. Furthermore, these findings expand the activity spectrum of CEPO to tissues outside the nervous system.

Schizophrenia, IX: Cognition in schizophrenia--the MATRICS initiative.

Symptoms of schizophrenia cluster into distinct domains: positive symptoms (hallucinations, delusions, thought disorder), negative symptoms (anhedonia, thought paucity, alogia), and cognitive dysfunction (attention, working memory, and executive dysfunction). The pharmacologic strategies, genetics, and disease courses associated with these domains differ from one another. Therefore, it has been hypothesized that they are distinct disease entities or at least have distinct pathophysiologies. For this reason, a useful strategy for treatment development may be to investigate these different symptom domains individually for distinct and optimal treatments. Existing antipsychotic drugs act by blocking dopamine and serotonin receptors, primarily targeting positive symptoms. Cognitive dysfunction remains a distinct and potentially important clinical target. The National Institute of Mental Health took the lead in organizing a government/academic/industry cooperative initiative called Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) to isolate distinct cognitive disruptions, identify putative molecular targets active in modulating cognition, find actual drug candidates for those targets, and promote the development of a new treatments for schizophrenia (see Figure). It is known that cognitive dysfunction in outpatient schizophrenia populations accounts for a great part of the residual psychosocial impairment standing in the way of these individuals finding homes, social networks, and employment. A treatment for cognitive dysfunction in these populations has great potential for a reduction of not only symptoms but also illness burden. So far, the MATRICS Initiative has identified 1) the areas of cognition that are specifically impaired in schizophrenia, 2) the most likely molecular targets involved, and 3) a cognitive battery that is sensitive and specific enough for broad use. As a next step, the NIMH will organize a cognitive testing network in clinical research settings to rigorously test new drugs for treatment of cognitive dysfunction. The goal is to find medications that will supplement current antipsychotic drugs by improving cognition in general or in specific subtypes and that can achieve recognition by the Food and Drug Administration (FDA) as indicated medications for this condition. While FDA recognition has not yet been fully realized, a road map to this goal is emerging. This road map may be a template for other innovative treatment development efforts.