TNF-alpha-induced apoptosis is prevented by erythropoietin treatment on SH-SY5Y cells

Whole transcriptome profiling of cardiac injury: insights from a neonatal mouse sepsis model

BACKGROUND

Neonatal sepsis is characterized by an excessive immune response, often leading to multiple organ failure, including cardiac injury, and is a major cause of morbidity and mortality in newborns. Understanding the molecular mechanisms of sepsis-induced cardiac injury is crucial for developing therapeutic strategies.

OBJECTIVE

To investigate transcriptomic changes and identify potential altered genes associated with cardiac injury in a neonatal sepsis model.

METHODS

A neonatal sepsis model was established by cecal slurry injection. RNA sequencing analysis was performed on cardiac tissues from sepsis and control groups, followed by functional enrichment analysis, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Interaction networks among mRNA, lncRNA, circRNA, and miRNA were constructed, and key regulatory genes were identified through protein-protein interaction (PPI) analysis.

RESULTS

A total of 1537 differentially expressed mRNAs, 287 lncRNAs, and 730 circRNAs were identified. Functional analysis revealed significant involvement in immune response and inflammatory regulation. PPI network analysis identified six key genes-Ccl5, Il-6, Pole, Mcm2, Mcm5, Mcm10-that were significantly expressed in sepsis-induced cardiac tissue. Additionally, lncRNAs and circRNAs were found to participate in myocardial injury by regulating immune and inflammatory pathways.

CONCLUSIONS

This study identified six key genes involved in immune and inflammatory responses, playing critical roles in sepsis-induced cardiac injury in neonates. These findings provide new insights into the pathogenesis of sepsis-induced cardiac injury and offer potential therapeutic targets.

Investigating the individual and combined effects of coenzyme Q10 and vitamin C on CLP-induced cardiac injury in rats

Sepsis-induced cardiac injury represents a major clinical challenge, amplifying the urgency for effective therapeutic interventions. This study aimed to delve into the individual and combined prophylactic effects of Vitamin C (Vit C) and Coenzyme Q10 (CoQ10) against inflammatory heart injury in a cecal ligation and puncture (CLP) induced polymicrobial sepsis rat model. Thirty adult female Sprague-Dawley rats were randomly divided into five groups: Control, CLP, Vitamin C, CoQ10, and Vit C + CoQ10, each consisting of six rats. Treatments were administered orally via gavage for 10 days prior to the operation. Eighteen hours post-sepsis induction, the animals were euthanized, and specimens were collected for analysis. The study examined variations in oxidative (TOS, OSI, MDA, MPO) and antioxidative markers (TAS, SOD, CAT, GSH), histopathological changes, inflammatory cytokine concentrations (TNF-α, IL-1β), nitric oxide (NO) dynamics, and cardiac indicators such as CK-MB. Impressively, the combined regimen markedly diminished oxidative stress, and antioxidative parameters reflected notable enhancements. Elevated NO levels, a central player in sepsis-driven inflammatory cascades, were effectively tempered by our intervention. Histological examinations corroborated the biochemical data, revealing diminished cardiac tissue damage in treated subjects. Furthermore, a marked suppression in pro-inflammatory cytokines was discerned, solidifying the therapeutic potential of our intervention. Interestingly, in certain evaluations, CoQ10 exhibited superior benefits over Vit C. Collectively, these findings underscore the potential therapeutic promise of Vit C and CoQ10 combination against septic cardiac injuries in rats.

Microglia-secreted TNF-α affects differentiation efficiency and viability of pluripotent stem cell-derived human dopaminergic precursors

Disease is a neurodegenerative disorder characterised by the progressive loss of dopaminergic cells of the substantia nigra pars compacta. Even though successful transplantation of dopamine-producing cells into the striatum exhibits favourable effects in animal models and clinical trials; transplanted cell survival is low. Since every transplant elicits an inflammatory response which can affect cell survival and differentiation, we aimed to study in vivo and in vitro the impact of the pro-inflammatory environment on human dopaminergic precursors. We first observed that transplanted human dopaminergic precursors into the striatum of immunosuppressed rats elicited an early and sustained activation of astroglial and microglial cells after 15 days' post-transplant. This long-lasting response was associated with Tumour necrosis factor alpha expression in microglial cells. In vitro, conditioned media from activated BV2 microglial cells increased cell death, decreased Tyrosine hydroxylase-positive cells and induced morphological alterations on human neural stem cells-derived dopaminergic precursors at two differentiation stages: 19 days and 28 days. Those effects were ameliorated by inhibition of Tumour necrosis factor alpha, a cytokine which was previously detected in vivo and in conditioned media from activated BV-2 cells. Our results suggest that a pro-inflammatory environment is sustained after transplantation under immunosuppression, providing a window of opportunity to modify this response to increase transplant survival and differentiation. In addition, our data show that the microglia-derived pro-inflammatory microenvironment has a negative impact on survival and differentiation of dopaminergic precursors. Finally, Tumour necrosis factor alpha plays a key role in these effects, suggesting that this cytokine could be an interesting target to increase the efficacy of human dopaminergic precursors transplantation in Parkinson's Disease.

Diglycolic acid inhibits succinate dehydrogenase activity, depletes mitochondrial membrane potential, and induces inflammation in an SH-SY5Y neuroblastoma model of neurotoxicity in vitro

Diethylene glycol is a toxic industrial solvent resulting in a well-defined toxidrome. Diglycolic acid (DGA) has been identified as the metabolite responsible for the nephrotoxicity and hepatotoxicity. These studies assess the mechanism of DGA-induced neurotoxicity, specifically addressing the known ability of DGA to chelate calcium (Ca²⁺) in solution and inhibit mitochondrial complex II. SH-SY5Y cells were seeded into 96-well plates to assess intracellular Ca²⁺ chelation, complex II activity, mitochondrial membrane potential (ΔΨm), ATP production, and release of inflammatory cytokines TNF-α and IL-1β with 2-, 4-, 6-, 24-, and 48-h DGA exposure. Peak Ca²⁺ chelation occurred at 4 h in cells treated with 6.25-50 mM DGA; however, effects were transient. Complex II activity was significantly decreased at all DGA concentrations tested, with 12.5 mM DGA causing 80% inhibition and 25 and 50 mM DGA causing 97 and 100% inhibition, respectively. Subsequently, 12.5-50 mM DGA concentrations significantly decreased ΔΨm at all time points. 50 mM DGA significantly increased release of TNF-α and IL-1β after 24 and 48 h with significantly decreased ATP production observed at the same time points and concentration. These studies demonstrate that the DGA-induced mechanism of SH-SY5Y cell death involves complex II inhibition leading to mitochondrial depolarization, and subsequent ATP depletion with accompanying inflammatory cytokine release. These results indicate a direct mechanism of DGA-induced neurotoxicity in vitro, similarly observed in other DEG-affected target organs.

TRAF4 Silencing Induces Cell Apoptosis and Improves Retinoic Acid Sensitivity in Human Neuroblastoma

Neuroblastoma (NB) is a pediatric malignancy that arises in the peripheral nervous system, and the prognosis in the high-risk group remains dismal, despite the breakthroughs in multidisciplinary treatments. The oral treatment with 13-cis-retinoic acid (RA) after high-dose chemotherapy and stem cell transplant has been proven to reduce the incidence of tumor relapse in children with high-risk neuroblastoma. However, many patients still have tumors relapsed following retinoid therapy, highlighting the need for the identification of resistant factors and the development of more effective treatments. Herein, we sought to investigate the potential oncogenic roles of the tumor necrosis factor (TNF) receptor-associated factor (TRAF) family in neuroblastoma and explore the correlation between TRAFs and retinoic acid sensitivity. We discovered that all TRAFs were efficiently expressed in neuroblastoma, but TRAF4, in particular, was found to be strongly expressed. The high expression of TRAF4 was associated with a poor prognosis in human neuroblastoma. The inhibition of TRAF4, rather than other TRAFs, improved retinoic acid sensitivity in two human neuroblastoma cell lines, SH-SY5Y and SK-N-AS cells. Further in vitro studies indicated that TRAF4 suppression induced retinoic acid-induced cell apoptosis in neuroblastoma cells, probably by upregulating the expression of Caspase 9 and AP1 while downregulating Bcl-2, Survivin, and IRF-1. Notably, the improved anti-tumor effects from the combination of TRAF4 knockdown and retinoic acid were confirmed in vivo using the SK-N-AS human neuroblastoma xenograft model. In conclusion, the highly expressed TRAF4 might be implicated in developing resistance to retinoic acid treatment in neuroblastoma, and the combination therapy with retinoic acid and TRAF4 inhibition may offer significant therapeutic advantages in the treatment of relapsed neuroblastoma.

Mechanism of Glucose Water as a Neural Injection: A Perspective on Neuroinflammation

The entrapment of peripheral nerves is associated with chronic neuroinflammation and neuropathic pain, and perineural injection therapy with glucose is emerging as an effective treatment for peripheral entrapment neuropathy. However, the mechanism underlying the pharmacological effect of glucose on nerves remains unclear. One of the hypothesized mechanisms is that glucose reduces neurogenic inflammation. Therefore, we investigated the effects of high glucose concentrations on cytokine-induced neuroinflammation in vitro. Human SH-SY5Y neuronal cells were challenged with 10 ng/mL TNF-α for 16 h and subsequently treated with different glucose concentrations (0–25 mM) for 24 h. Cell viability was evaluated using the diphenyltetrazolium bromide assay, and proinflammatory cytokine levels were assessed using ELISA and quantitative PCR. In addition, mRNA levels of NF-κB and cyclooxygenase-2 were analyzed using quantitative PCR. Exposure to 10 ng/mL TNF-α resulted in decreased viability of SH-SY5Y cells and significant upregulation of IL-6, IL-1β, NF-κB, and cyclooxygenase-2. Subsequent exposure to high glucose levels (25 mM) markedly reduced the upregulation of IL-6, IL-1β, cyclooxygenase-2, and NF-κB, and restored the functional metabolism of SH-SY5Y cells, compared with that of the normal glucose control. Our findings suggest that high glucose concentrations can mitigate TNF-α-induced NF-κB activation, upregulation of proinflammatory cytokines, and metabolic dysfunction.

Erythropoietin and derivatives: Potential beneficial effects on the brain

Erythropoietin (Epo), the main erythropoiesis-stimulating factor widely prescribed to overcome anemia, is also known nowadays for its cytoprotective action on non-hematopoietic tissues. In this context, Epo showed not only its ability to cross the blood-brain barrier, but also its expression in the brain of mammals. In clinical trials, recombinant Epo treatment has been shown to stimulate neurogenesis; improve cognition; and activate antiapoptotic, antioxidant, and anti-inflammatory signaling pathways. These mechanisms, proposed to characterize a neuroprotective property, opened new perspectives on the Epo pharmacological potencies. However, many questions arise about a possible physiological role of Epo in the central nervous system (CNS) and the factors or environmental conditions that induce its expression. Although Epo may be considered a strong candidate to be used against neuronal damage, long-term treatments, particularly when high Epo doses are needed, may induce thromboembolic complications associated with increases in hematocrit and blood viscosity. To avoid these adverse effects, different Epo analogs without erythropoietic activity but maintaining neuroprotection ability are currently being investigated. Carbamylated erythropoietin, as well as alternative molecules like Epo fusion proteins and partial peptides of Epo, seems to match this profile. This review will focus on the discussion of experimental evidence reported in recent years linking erythropoietin and CNS function through investigations aimed at finding benefits in the treatment of neurodegenerative diseases. In addition, it will review the proposed mechanisms for novel derivatives which may clarify and, eventually, improve the neuroprotective action of Epo.

STAT5 as a Key Protein of Erythropoietin Signalization

Erythropoietin (EPO) acts on multiple tissues through its receptor EPOR, a member of a cytokine class I receptor superfamily with pleiotropic effects. The interaction of EPO and EPOR triggers the activation of several signaling pathways that induce erythropoiesis, including JAK2/STAT5, PI3K/AKT, and MAPK. The canonical EPOR/JAK2/STAT5 pathway is a known regulator of differentiation, proliferation, and cell survival of erythroid progenitors. In addition, its role in the protection of other cells, including cancer cells, is under intense investigation. The involvement of EPOR/JAK2/STAT5 in other processes such as mRNA splicing, cytoskeleton reorganization, and cell metabolism has been recently described. The transcriptomics, proteomics, and epigenetic studies reviewed in this article provide a detailed understanding of EPO signalization. Advances in this area of research may be useful for improving the efficacy of EPO therapy in hematologic disorders, as well as in cancer treatment.

Current Evidence on the Protective Effects of Recombinant Human Erythropoietin and Its Molecular Variants against Pathological Hallmarks of Alzheimer's Disease

Substantial evidence in the literature demonstrates the pleiotropic effects of the administration of recombinant human erythropoietin (rhEPO) and its molecular variants in different tissues and organs, including the brain. Some of these reports suggest that the chemical properties of this molecule by itself or in combination with other agents (e.g., growth factors) could provide the necessary pharmacological characteristics to be considered a potential protective agent in neurological disorders such as Alzheimer’s disease (AD). AD is a degenerative disorder of the brain, characterized by an aberrant accumulation of amyloid β (Aβ) and hyperphosphorylated tau (tau-p) proteins in the extracellular and intracellular space, respectively, leading to inflammation, oxidative stress, excitotoxicity, and other neuronal alterations that compromise cell viability, causing neurodegeneration in the hippocampus and the cerebral cortex. Unfortunately, to date, it lacks an effective therapeutic strategy for its treatment. Therefore, in this review, we analyze the evidence regarding the effects of exogenous EPOs (rhEPO and its molecular variants) in several in vivo and in vitro Aβ and tau-p models of AD-type neurodegeneration, to be considered as an alternative protective treatment to this condition. Particularly, we focus on analyzing the differential effect of molecular variants of rhEPO when changes in doses, route of administration, duration of treatment or application times, are evaluated for the improved cellular alterations generated in this disease. This narrative review shows the evidence of the effectiveness of the exogenous EPOs as potential therapeutic molecules, focused on the mechanisms that establish cellular damage and clinical manifestation in the AD.

A Systemic Inflammatory Signature Reflecting Cross Talk Between Innate and Adaptive Immunity Is Associated With Incident Polyneuropathy: KORA F4/FF4 Study

Prospective analyses of biomarkers of inflammation and distal sensorimotor polyneuropathy (DSPN) are scarce and limited to innate immunity. We therefore aimed to assess associations between biomarkers reflecting multiple aspects of immune activation and DSPN. The study was based on 127 case subjects with incident DSPN and 386 noncase subjects from the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4/FF4 cohort (follow-up 6.5 years). Proximity extension assay technology was used to measure serum levels of biomarkers of inflammation. Of 71 biomarkers assessed, 26 were associated with incident DSPN. After adjustment for multiple testing, higher levels of six biomarkers remained related to incident DSPN. Three of these proteins (MCP-3/CCL7, MIG/CXCL9, IP-10/CXCL10) were chemokines, and the other three (DNER, CD40, TNFRSF9) were soluble forms of transmembrane receptors. The chemokines had neurotoxic effects on neuroblastoma cells in vitro. Addition of all six biomarkers improved the C statistic of a clinical risk model from 0.748 to 0.783 (P = 0.011). Pathway analyses indicated that multiple cell types from innate and adaptive immunity are involved in the development of DSPN. We thus identified novel associations between biomarkers of inflammation and incident DSPN pointing to a complex cross talk between innate and adaptive immunity in the pathogenesis of the disease.

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.

Characterization of SH-SY5Y human neuroblastoma cell growth over glass and SU-8 substrates

The physical properties of substrates can have profound effects on the structure and function of cultured cells. In this study, we aimed to examine the viability, adherence, and morphological and functional variations between SH-SY5Y human neuroblastoma cells cultured on SU-8 surfaces compared with control surfaces composed of borosilicate glass, which are routinely used for cell culture. The SU-8 polymer has been extensively studied for its biocompatibility, but there has been little investigation into the characteristic differences between cells cultured on SU-8 when compared with glass. SH-SY5Y cells were cultured within polydimethylsiloxane wells on both SU-8 and glass substrates for up to 72 h after which flow cytometry and enzyme-linked immunosorbent assay analysis was performed to examine cell viability and neurotoxicity. Immunocytochemistry was also performed to analyze the morphological and functional characteristics of the cells. Atomic force microscopy was performed to measure surface roughness and to map cell-substrate interactions. Nanoindentation testing was used to characterize the mechanical properties of polymer surface. Results showed that SH-SY5Y cells grown on SU-8 have significantly improved viability and increased morphological and functional characteristics of neurodevelopment. The results from this study suggest that the mechanical properties of the polymer are optimal for the study of cultured cell lines, which could account for the increased viability, adherence, and morphological and functional characteristics of neurodevelopment. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2129-2138, 2017.

Anthoxanthin Polyphenols Attenuate Aβ Oligomer-induced Neuronal Responses Associated with Alzheimer's Disease

AIMS

Epidemiological evidence implicates polyphenols as potential natural therapeutics for Alzheimer's disease (AD). To investigate this prospect, five anthoxanthin polyphenols were characterized for their ability to reduce amyloid-β (Aβ) oligomer-induced neuronal responses by two mechanisms of action, modulation of oligomerization and antioxidant activity, as well as the synergy between these two mechanisms.

METHODS

Anthoxanthin oligomerization modulation and antioxidant capabilities were evaluated and correlated with anthoxanthin attenuation of oligomer-induced intracellular reactive oxygen species (ROS) and caspase activation using human neuroblastoma cell treatments designed to isolate these mechanisms of action and to achieve dual-action.

RESULTS

While modulation of oligomerization resulted in only minor reductions to neuronal responses, anthoxanthin antioxidant action significantly attenuated oligomer-induced intracellular ROS and caspase activation. Kaempferol uniquely exhibited synergism when the two mechanisms functioned in concert, leading to a pronounced reduction in both ROS and caspase activation.

CONCLUSIONS

Together, these findings identify the dominant mechanism by which these anthoxanthins attenuate Aβ oligomer-induced neuronal responses, elucidate their prospective synergy, and demonstrate the potential of anthoxanthin polyphenols as natural AD therapeutics.

Management of anemia with erythropoietic-stimulating agents in children with chronic kidney disease

Anemia management is an important component of the care provided to children with chronic kidney disease (CKD) and influences both morbidity and mortality risk. The introduction of recombinant human erythropoietin to the treatment regimen three decades ago revolutionized the therapy and significantly decreased the need for repeated blood transfusions and exposure to associated risks. Recent data on the efficacy and complications associated with erythropoietic-stimulating agent (ESA) usage has, however, prompted a reassessment of treatment-related recommendations. This review will address these recommendations, in addition to describing pediatric outcomes associated with current ESAs and presenting information on alternative ESAs, many of which will likely soon be incorporated into clinical practice.

Erythropoietin, a novel versatile player regulating energy metabolism beyond the erythroid system

Erythropoietin (EPO), the required cytokine for promoting the proliferation and differentiation of erythroid cells to stimulate erythropoiesis, has been reported to act as a pleiotropic cytokine beyond hematopoietic system. The various activities of EPO are determined by the widespread distribution of its cell surface EPO receptor (EpoR) in multiple tissues including endothelial, neural, myoblasts, adipocytes and other cell types. EPO activity has been linked to angiogenesis, neuroprotection, cardioprotection, stress protection, anti-inflammation and especially the energy metabolism regulation that is recently revealed. The investigations of EPO activity in animals and the expression analysis of EpoR provide more insights on the potential of EPO in regulating energy metabolism and homeostasis. The findings of crosstalk between EPO and some important energy sensors and the regulation of EPO in the cellular respiration and mitochondrial function further provide molecular mechanisms for EPO activity in metabolic activity regulation. In this review, we will summarize the roles of EPO in energy metabolism regulation and the activity of EPO in tissues that are tightly associated with energy metabolism. We will also discuss the effects of EPO in regulating oxidative metabolism and mitochondrial function, the interactions between EPO and important energy regulation factors, and the protective role of EPO from stresses that are related to metabolism, providing a brief overview of previously less appreciated EPO biological function in energy metabolism and homeostasis.

Type-1 interferons contribute to oxygen glucose deprivation induced neuro-inflammation in BE(2)M17 human neuroblastoma cells

BACKGROUND

Hypoxic-ischaemic injuries such as stroke and traumatic brain injury exhibit features of a distinct neuro-inflammatory response in the hours and days post-injury. Microglial activation, elevated pro-inflammatory cytokines and macrophage infiltration contribute to core tissue damage and contribute to secondary injury within a region termed the penumbra. Type-1 interferons (IFNs) are a super-family of pleiotropic cytokines that regulate pro-inflammatory gene transcription via the classical Jak/Stat pathway; however their role in hypoxia-ischaemia and central nervous system neuro-inflammation remains unknown. Using an in vitro approach, this study investigated the role of type-1 IFN signalling in an inflammatory setting induced by oxygen glucose deprivation (OGD).

METHODS

Human BE(2)M17 neuroblastoma cells or cells expressing a type-1 interferon-α receptor 1 (IFNAR1) shRNA or negative control shRNA knockdown construct were subjected to 4.5 h OGD and a time-course reperfusion period (0 to 24 h). Q-PCR was used to evaluate IFNα, IFNβ, IL-1β, IL-6 and TNF-α cytokine expression levels. Phosphorylation of signal transducers and activators of transcription (STAT)-1, STAT-3 and cleavage of caspase-3 was detected by western blot analysis. Post-OGD cellular viability was measured using a MTT assay.

RESULTS

Elevated IFNα and IFNβ expression was detected during reperfusion post-OGD in parental M17 cells. This correlated with enhanced phosphorylation of STAT-1, a downstream type-1 IFN signalling mediator. Significantly, ablation of type-1 IFN signalling, through IFNAR1 knockdown, reduced IFNα, IFNβ, IL-6 and TNF-α expression in response to OGD. In addition, MTT assay confirmed the IFNAR1 knockdown cells were protected against OGD compared to negative control cells with reduced pro-apoptotic cleaved caspase-3 levels.

CONCLUSIONS

This study confirms a role for type-1 IFN signalling in the neuro-inflammatory response following OGD in vitro and suggests its modulation through therapeutic blockade of IFNAR1 may be beneficial in reducing hypoxia-induced neuro-inflammation.

The influence of the pleiotropic action of erythropoietin and its derivatives on nephroprotection

Erythropoietin (EPO) is traditionally described as a hematopoietic cytokine or growth hormone regulating proliferation, differentiation, and survival of erythroid progenitors. The use of EPO in patients with chronic kidney disease (CKD) was a milestone achievement in the treatment of anemia. However, EPO involves some degree of risk, which increases with increasing hemoglobin levels. A growing number of studies have assessed the renoprotective effects of EPO in acute kidney injury (AKI) or CKD. Analysis of the biological effects of erythropoietin and pathophysiology of CKD in these studies suggests that treatment with erythropoiesis-stimulating agents (ESAs) may exert renoprotection by pleiotropic actions on several targets and directly or indirectly slow the progression of CKD. By reducing ischemia and oxidative stress or strengthening anti-apoptotic processes, EPO may prevent the development of interstitial fibrosis and the destruction of tubular cells. Furthermore, it could have a direct protective impact on the integrity of the interstitial capillary network through its effects on endothelial cells and promotion of vascular repair, or modulate inflammation response. Thus, it is biologically plausible to suggest that correcting anemia with ESAs could slow the progression of CKD.                         The aim of this article is to discuss these possible renoprotection mechanisms and provide a comprehensive overview of erythropoietin and its derivatives.

Protective action of erythropoietin on neuronal damage induced by activated microglia

Inflammation is a physiological defense response, but may also represent a potential pathological process in neurological diseases. In this regard, microglia have a crucial role in either progression or amelioration of degenerative neuronal damage. Because of the role of hypoxia in pro-inflammatory mechanisms in the nervous system, and the potential anti-inflammatory protective effect of erythropoietin (Epo), we focused our investigation on the role of this factor on activation of microglia and neuroprotection. Activation of microglial cells (EOC-2) was achieved by chemical hypoxia induced by cobalt chloride (CoCl2 ) and characterized by increased levels of nitrite, tumor necrosis factor-α and reactive oxygen species production, as well as up-regulation of inducible nitric oxide synthase expression. Under these conditions, cell proliferation data and proliferating cell nuclear antigen (PCNA) staining demonstrated a mitogenic effect of chemical hypoxia. Even though pre-treatment with Epo did not prevent nitrite production, inducible nitric oxide synthase protein expression or tumor necrosis factor-α secretion, it prevented the oxidative stress induced by CoCl2 as well as cell proliferation. Neuronal cells (SH-SY5Y) cultured in the presence of conditioned medium from activated EOC-2 cells or macrophages (RAW 264.7) developed significant apoptosis, an effect that was abolished by Epo via Epo/Epo receptor activation. The results show that even though Epo did not exert a direct anti-inflammatory effect on microglia activation, it did increase the resistance of neurons to subsequent damage from pro-inflammatory agents. In addition to its anti-apoptotic ability, the Epo antioxidant effect may have an indirect influence on neuronal survival by modulation of the pro-inflammatory environment.

Alternative erythropoietin-mediated signaling prevents secondary microvascular thrombosis and inflammation within cutaneous burns

Alternate erythropoietin (EPO)-mediated signaling via the heteromeric receptor composed of the EPO receptor and the β-common receptor (CD131) exerts the tissue-protective actions of EPO in various types of injuries. Herein we investigated the effects of the EPO derivative helix beta surface peptide (synonym: ARA290), which specifically triggers alternate EPO-mediated signaling, but does not bind the erythropoietic EPO receptor homodimer, on the progression of secondary tissue damage following cutaneous burns. For this purpose, a deep partial thickness cutaneous burn injury was applied on the back of mice, followed by systemic administration of vehicle or ARA290 at 1, 12, and 24 h postburn. With vehicle-only treatment, wounds exhibited secondary microvascular thrombosis within 24 h postburn, and subsequent necrosis of the surrounding tissue, thus converting to a full-thickness injury within 48 h. On the other hand, when ARA290 was systemically administered, patency of the microvasculature was maintained. Furthermore, ARA290 mitigated the innate inflammatory response, most notably tumor necrosis factor-alpha-mediated signaling. These findings correlated with long-term recovery of initially injured yet viable tissue components. In conclusion, ARA290 may be a promising therapeutic approach to prevent the conversion of partial- to full-thickness burn injuries. In a clinical setting, the decrease in burn depth and area would likely reduce the necessity for extensive surgical debridement as well as secondary wound closure by means of skin grafting. This use of ARA290 is consistent with its tissue-protective properties previously reported in other models of injury, such as myocardial infarction and hemorrhagic shock.

Erythropoietin protects adult retinal ganglion cells against NMDA-, trophic factor withdrawal-, and TNF-α-induced damage

Purpose

This study aimed to evaluate the neuroprotective effect of EPO in the presence of N-methyl-d-aspartate (NMDA)-, trophic factor withdrawal (TFW)-, and tumor necrosis factor-alpha (TNF-α)-induced toxicity on total, small, and large retinal ganglion cells (RGCs).

Methods

Retinal cells from adult rats were cultured in a medium containing brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), basic fibroblast growth factor (bFGF), and forskolin. Expression of RGC markers and EPOR was examined using immunocytochemistry. RGCs were classified according to their morphological properties. Cytotoxicity was induced by NMDA, TFW, or TNF-α. RGC survival was assessed by counting thy-1 and neurofilament-l double-positive cells.

Results

EPO offered dose-dependent (EC₅₀ = 5.7 ng/mL) protection against NMDA toxicity for small RGCs; protection was not significant for large RGCs. Time-course analysis showed that the presence of EPO either before or after NMDA exposure gave effective protection. For both small and large RGCs undergoing trophic factor withdrawal, EPO at concentrations of 1, 10, or 100 ng/mL improved survival. However, EPO had to be administered soon after the onset of injury to provide effective protection. For TNF-α-induced toxicity, survival of small RGCs was seen only for the highest examined concentration (100 ng/mL) of EPO, whereas large RGCs were protected at concentrations of 1, 10, or 100 ng/mL of EPO. Time-course analysis showed that pretreatment with EPO provided protection only for large RGCs; early post-treatment with EPO protected both small and large RGCs. Inhibitors of signal transduction and activators of transcription such as (STAT)-5, mitogen-activated protein kinases (MAPK)/extracellular-regulated kinase (ERK), and phosphatidyl inositol-3 kinase (PI3K)/Akt impaired the protective effect of EPO on RGCs exposed to different insults.

Conclusion

EPO provided neuroprotection to cultured adult rat RGCs; however, the degree of protection varied with the type of toxic insult, RGC subtype, and timing of EPO treatment.

The erythropoietin-derived peptide ARA290 reverses mechanical allodynia in the neuritis model

Studies on the neuritis model suggest that in many patients with neuropathic pain, symptoms may be due to nerve inflammation rather than frank nerve injury. Treatments for these patients are often ineffective. The neuroprotective and hematopoietic agent erythropoietin (EPO) has been shown to reverse pain behaviors in nerve injury models and therefore may be of therapeutic benefit. However, EPO can cause thrombosis. ARA290 is an analog of EPO that has the neuroprotective activities of EPO without stimulating hematopoiesis. The present study has examined the effects of ARA290 on pain behavior in the neuritis model. Following neuritis induction, 30 or 120 μg/kg ARA290 or saline vehicle was injected intraperitoneally into rats daily from day 1 post surgery. Animals were assessed for mechanical allodynia and heat hyperalgesia. Levels of the cytokine tumor necrosis factor-α (TNF-α) and chemokine (CC motif) ligand 2 (CCL2) mRNA were also assessed using polymerase chain reaction. Vehicle-treated neuritis animals (n=20) developed signs of mechanical allodynia and heat hyperalgesia that reached a maximum on day 4 and 3 of testing, respectively. Treatment with either 30 (n=11) or 120 μg/kg ARA290 (n=9) prevented the development of mechanical allodynia. However, ARA290 did not significantly affect heat hyperalgesia. There was no significant difference between the effects of each drug dose (p<0.05, unpaired t test comparing area under the curve for mechanical allodynia). The levels of CCL2 and TNF-α mRNA in the nerve and Gelfoam were not significantly different following 120 μg/kg ARA290 treatment (n=3-7) compared to vehicle-treated animals (n=3-7; p=0.24; unpaired t tests). In summary, ARA290 may be beneficial in the treatment of neuropathic pain symptoms where signs of nerve injury are absent on clinical assessment. The mechanisms of action do not appear to involve the inhibition of TNF-α or CCL2 production.

Erythropoietin and Wnt1 govern pathways of mTOR, Apaf-1, and XIAP in inflammatory microglia

Inflammatory microglia modulate a host of cellular processes in the central nervous system that include neuronal survival, metabolic fluxes, foreign body exclusion, and cellular regeneration. Elucidation of the pathways that oversee microglial survival and integrity may offer new avenues for the treatment of neurodegenerative disorders. Here we demonstrate that erythropoietin (EPO), an emerging strategy for immune system modulation, prevents microglial early and late apoptotic injury during oxidant stress through Wnt1, a cysteine-rich glycosylated protein that modulates cellular development and survival. Loss of Wnt1 through blockade of Wnt1 signaling or through the gene silencing of Wnt1 eliminates the protective capacity of EPO. Furthermore, endogenous Wnt1 in microglia is vital to preserve microglial survival since loss of Wnt1 alone increases microglial injury during oxidative stress. Cellular protection by EPO and Wnt1 intersects at the level of protein kinase B (Akt1), the mammalian target of rapamycin (mTOR), and p70S6K, which are necessary to foster cytoprotection for microglia. Downstream from these pathways, EPO and Wnt1 control "anti-apoptotic" pathways of microglia through the modulation of mitochondrial membrane permeability, the release of cytochrome c, and the expression of apoptotic protease activating factor-1 (Apaf-1) and X-linked inhibitor of apoptosis protein (XIAP). These studies offer new insights for the development of innovative therapeutic strategies for neurodegenerative disorders that focus upon inflammatory microglia and novel signal transduction pathways.

IL-1β down-regulates ADAMTS-13 mRNA expression in cells of the central nervous system

ADAMTS-13 is the Von Willebrand factor (vWF) cleaving protease, responsible for the cleavage and down-regulation of the pro-thrombotic properties of ultra large VWF multimers. It is expressed predominantly by the hepatic stellate cells of the liver, but is also found to be expressed in other tissues, including brain. Reduced ADAMTS-13 is associated with a variety of thrombotic microangiopathies. Since the cellular origin and regulation of ADAMTS-13 expression in the brain is unknown, we aimed to investigate this in four different central nervous system (CNS)-derived cell lines, SHSY-5Y (human neuroblastoma), U373 (human astroglioma), CHME-3 (human foetal microglia) and hCMEC/D3 (adult human brain endothelial cells). All cell lines expressed ADAMTS-13 mRNA constitutively with neuroblastoma cells showing the highest expression. Interleukin (IL)-1β down-regulated ADAMTS-13 mRNA expression in astroglioma cells and microglial cells whereas TNF and IL-6 treatment showed no significant differences in ADAMTS-13 mRNA expression in any cell line tested. ADAMTS-13 protein expression was reduced in a dose-dependent manner only in astroglioma cells following stimulation by IL-1β. The ability of IL-1β to significantly reduce ADAMTS-13 mRNA expression in human microglia and astroglioma cells suggests a role in the haemostasis of the local microenvironment under inflammatory conditions. This is the first report of ADAMTS-13 expression in cells of the CNS; however, its function remains to be determined.

Expression of Bcl2l1, Clcf1, IL-28ra and Pias1 in the mouse heart after single and repeated administration of chlorpromazine

Several chlorpromazine (CPZ)-related deaths have been suspected in forensic autopsies but these are difficult to identify precisely because only low concentrations of CPZ can usually be detected. Patients on CPZ therapy exhibit various cardiovascular diseases, such as arrhythmia and cardiomyopathy. As our previous study revealed that CPZ administration affects the expression of immediate early genes that are induced before any other genes, we expected that CPZ probably affects the heart and, in particular, the gene expression in heart. CPZ changes tumor necrosis factor (TNF) production. After stimulation of TNF, the Janus kinase signal transducer and activator of transcription (JAK-STAT) signaling pathway is activated via TNF receptor (TNF-R), and the pathway participates in the regulation of cellular responses such as apoptosis [1]. We used semi-arrays to determine the JAK-STAT signaling pathway in a mouse cardiomyocyte cell line, HL-1, and real-time quantitative-PCR to determine whether the semi-array data applied in vivo in mouse heart after single and once-daily repeated (1-4weeks) low-dose (0.75mg/kg) or high-dose (7.5mg/kg) CPZ treatment. We found that expression of B cell lymphoma 2 like 1 (Bcl2l1), Cardiotrophin-like cytokine factor 1 (Clcf1), Interleukin-28 receptor alpha (IL-28ra) and Protein inhibitor of activated STAT-1 (Pias1) were significantly changed in vivo. All these genes are associated with apoptosis. The expression level of Bcl2l1 was elevated after a single high-dose CPZ treatment and after 1week of repeated high doses, but returned to baseline from week 2 to week 4. Clcf1 and IL-28ra expression increased from week 2 or 3 after low-dose CPZ treatment. Pias1 also increased from week 2 after low-dose CPZ treatment. Our results indicate that different doses of CPZ can induce distinct patterns of gene expression for preventing the apoptotic progression in mouse cardiomyocytes, suggesting that CPZ can affect cardiomyocytes via the JAK-STAT signaling pathway and that this might lead to cardiomyopathy. In addition, our data may help to clarify the pathophysiology of cardiomyopathy induced by CPZ and to diagnose cardiac sudden death following CPZ treatment.

Erythropoietin attenuates inflammatory factors and cell death in neonatal rats with intracerebral hemorrhage

Stroke affects infants at a rate of 26/100,000 live births each year. Of these strokes, approximately 6.7 are hemorrhagic strokes. Erythropoietin (EPO) is an anti-apoptotic and neuroprotective hormone. In adult rodents, EPO attenuates inflammatory factor expression and blood-brain barrier damage after intracerebral hemorrhage (ICH). However, the effect of EPO in neonatal ICH stroke remains unexplored. This investigation aimed to elucidate the underpinnings of inflammation after ICH in postnatal day 7 (P7) rats and the effect of human recombinant EPO (hrEPO) treatment on ICH-induced inflammation. The P7 rat pups were pretreated with hrEPO (5,000 U/kg i.p.) or saline vehicle 4 h prior to the induction of ICH by blood injection into the right cerebral cortex and basal ganglia. Supplemental half doses of hrEPO treatment or saline injections were subsequently given 16 h after ICH induction. Real-time PCR done 24 h after ICH showed reductions in interleukin1-β (IL1-β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNFα) mRNA expression in the basal ganglia of the hrEPO-treated rats compared to saline-treated rats. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining indicated fewer dying cells in the hrEPO-treated brain. Our data suggest that hrEPO has an anti-inflammatory action in neonates after ICH. The suppression of inflammatory cascades likely contributes to hrEPO's neuroprotective effect, which may be explored as a therapeutic treatment for ICH.

Cellular and molecular mechanisms regulating the hepatic erythropoietin expression during acute-phase response: a role for IL-6

The source of circulating erythropoietin (EPO), the mediators and the mechanisms involved in the upregulation of EPO gene expression during acute-phase reaction are still poorly understood. Acute-phase reaction was induced by either intramuscular turpentine oil (TO) or intraperitoneal lipopolysaccharide (LPS) administration into wild-type and interleukin (IL)-6 knockout (KO) mice. Animals were killed at different time points and blood, liver and muscle tissue were collected. Serum levels of EPO were measured by enzyme-linked immunoadsorbent assay; liver and injured muscle samples were processed for RNA isolation and for protein analysis. EPO, hypoxia-inducible factors 1alpha and 2alpha (HIF-1alpha and HIF-2alpha) mRNA were analyzed by RT-PCR and the protein levels were analyzed by western blot and electrophoretic mobility shift assay. HIF-1alpha and HIF-2alpha localization was performed through immunofluorescence staining. EPO, HIF-1 and HIF-2 gene and protein expression levels were also analyzed in isolated mouse hepatocytes after stimulation with IL-6. In the wild-type animals, EPO serum levels increased dramatically at 12 h after the insults together with the hepatic gene expression. In TO-treated animals, the EPO gene expression reached an 8.2-fold increase at 12 h, and in LPS-treated mice a similar induction was recorded at 6 h (about 4.5-fold increase). In the IL-6KO strain, the upregulation after the inflammatory stimuli was much lower (only 2.0-fold increase). A progressive upregulation of HIF-1alpha and HIF-2alpha was detectable until 6 h after the insults, but only HIF-1alpha upregulation was reduced in IL-6KO mice. In isolated hepatocytes, stimulation with a single dose of IL-6 induced a nuclear accumulation of HIF-1alpha, in parallel with an increase of EPO mRNA. No effect on HIF-2alpha expression was found. IL-6 appears to be the main regulator of EPO gene expression and a major contributor for HIF-1alpha induction in hepatocytes and Kupffer cells during acute-phase response. The increase of HIF-2alpha, predominantly expressed in endothelial cells and fibroblast-like cells, seems not to be affected by the lack of IL-6.

Differential antiapoptotic effect of erythropoietin on undifferentiated and retinoic acid-differentiated SH-SY5Y cells

Erythropoietin (Epo) is known to have a significant role in tissues outside the hematopoietic system. In this work, we investigated the function of Epo in cells of neuronal origin subjected to differentiation. Treatment of SH-SY5Y cells with all-trans-retinoic acid (atRA) generated differentiated neuron-like cells, observed by increased expression of neuronal markers and morphological changes. Exposure of undifferentiated cells to proapoptotic stimuli such as staurosporine, TNF-alpha, or hypoxia, significantly increased programmed cell death, which was prevented by previous treatment with Epo. In contrast, atRA-differentiated cultures showed cell resistance to apoptosis. No additional effect of Epo was detected in previously differentiated cells. The inhibition of the PI3K/Akt pathway by Ly294002 abrogated the protective effects induced by either Epo or atRA. The effect of atRA was mediated by an increased expression of Bcl-2 whereas the Epo treatment upregulated not only Bcl-2 but also Bcl-xL. This upregulation by Epo was not detected in atRA-differentiated cells, thus confirming the lack of the protective effect of Epo. As expected, assays with AG490, an inhibitor of Jak2, blocked the Epo action only in undifferentiated cells. This reduced neuroprotective function of Epo on SH-SY5Y differentiated cells could be explained at least in part by downregulation of the Epo receptor expression, which was observed in atRA-differentiated cells. This study shows differential cellular protection induced by Epo at two stages of SH-SY5Y differentiation. The results allow us to suggest that this differential cell behavior can be ascribed to the interaction between atRA and the signaling pathways mediated by Epo.

Drug targeting of erythropoietin across the primate blood-brain barrier with an IgG molecular Trojan horse

Erythropoietin (EPO) is a neurotrophic factor that could be developed as a new drug for brain disorders. However, EPO does not cross the blood-brain barrier (BBB). In the present study, human EPO was re-engineered by fusion to the carboxyl terminus of the heavy chain of a chimeric monoclonal antibody (MAb) to the human insulin receptor (HIR). The HIRMAb acts as a molecular Trojan horse to ferry the EPO into the brain via receptor-mediated transport on the endogenous BBB insulin receptor. The HIRMAb-EPO fusion protein was immunoreactive with antibodies to both human IgG and EPO. The HIRMAb-EPO fusion protein bound with high affinity to the extracellular domain of both the HIR (ED(50) = 0.21 +/- 0.05 nM) and the EPO receptor (ED(50) = 0.30 +/- 0.01 nM) and activated thymidine incorporation into human TF-1 cells with an ED(50) of 0.1 nM. Differentially radiolabeled EPO and the HIRMAb-EPO fusion protein were injected intravenously into adult rhesus monkeys. Whereas EPO did not cross the primate BBB, the HIRMAb-EPO fusion protein was rapidly transported into brain, at levels that produce pharmacologic elevations in brain EPO at small systemic doses. The HIRMAb fusion protein selectively targeted the brain relative to peripheral organs. In conclusion, a novel IgG-EPO fusion protein has been engineered, expressed, and shown to be bifunctional with retention of high-affinity binding to both the insulin and EPO receptors. The IgG-EPO fusion protein represents a new class of EPO neurotherapeutics that has been specifically re-engineered to penetrate the human BBB.

Oxidative stress: Biomarkers and novel therapeutic pathways

Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO) and members of the mammalian forkhead transcription factors of the O class (FoxOs) may offer the greatest promise for new treatment regimens since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. However, biological outcome with EPO and FoxOs may sometimes be both unexpected and undesirable that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as complicated role EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.

New strategies for Alzheimer's disease and cognitive impairment

Approximately five million people suffer with Alzheimer's disease (AD) and more than twenty-four million people are diagnosed with AD, pre-senile dementia, and other disorders of cognitive loss worldwide. Furthermore, the annual cost per patient with AD can approach $200,000 with an annual population aggregate cost of $100 billion. Yet, complete therapeutic prevention or reversal of neurovascular injury during AD and cognitive loss is not achievable despite the current understanding of the cellular pathways that modulate nervous system injury during these disorders. As a result, identification of novel therapeutic targets for the treatment of neurovascular injury would be extremely beneficial to reduce or eliminate disability from diseases that lead to cognitive loss or impairment. Here we describe the capacity of intrinsic cellular mechanisms for the novel pathways of erythropoietin and forkhead transcription factors that may offer not only new strategies for disorders such as AD and cognitive loss, but also function as biomarkers for disease onset and progression.

Erythropoietin, forkhead proteins, and oxidative injury: biomarkers and biology

Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO), and members of the mammalian forkhead transcription factors of the O class (FoxOs), may offer the greatest promise for new treatment regimens, since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. Yet, EPO and FoxOs may sometimes have unexpected and undesirable effects that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as the complex role that EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.