Expression of Erythropoietin in the Spinal Cord of Lewis Rats with Experimental Autoimmune Encephalomyelitis

Abstract

Background and PurposeaaErythropoietin (Epo), originally recognized for its central role in erythropoiesis, has been shown to improve the outcomes in patients with various neurological disorders. The aim of this study was to elucidate the Epo expression pattern in the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis (EAE) and to assess the systemic effect of Epo during the course of EAE.MethodsaaWe used an EAE model induced in Lewis rats by immunization with myelin basic protein. Immunized rats were given recombinant human Epo (rhEpo) intraperitoneally at a dose of 5,000 U/kg for 7 consecutive days, either starting on day 3 post-immunization (five rats) or on the day of clinical symptom onset (score ≥1, five rats). After immunization, the rats were observed daily for clinical signs of EAE. Epo expression was investigated by Western blot analysis and immunohistochemistry.ResultsaaWestern blot analysis showed that, Epo expression was significantly elevated relative to control in the rat spinal cord during the peak stage of EAE (p<0.05), and then decreased thereafter. Immunohistochemistry demonstrated that Epo was expressed in some neurons and glial cells. Epo immunoreactivity was detected in ED1-positive macrophages and astrocytes in EAE lesions. Furthermore, we found that the intraperitoneal administration of rhEpo reduced both the disease severity and duration of paralysis in EAE rats, and reduced macrophage activity and increased Epo activity.ConclusionsaaBased on these findings, we postulate that Epo expression begins to increase at the start of EAE and that rhEpo administration leads to functional recovery from EAE paralysis.

Erythropoietin and autoimmune neuroinflammation: lessons from experimental autoimmune encephalomyelitis and experimental autoimmune neuritis

“…Following CNS injury, EPO is stimulated with hypoxia-inducible factors, and has been found to be activated and to protect neurons after ischemia-reperfusion injury in animal models [5, 52]. With the immunization of organ-specific antigens, semi-quantitative analysis has demonstrated that the expression of EPO is upregulated in the CNS [20] and in the PNS [36], which may contribute to the protection of neurons either by paracrine or autocrine mechanisms. Furthermore, EPO has been immune-detected in neurons, glial cells, and macrophages in EAE [20] and EAN [36] models.…”

“…With the immunization of organ-specific antigens, semi-quantitative analysis has demonstrated that the expression of EPO is upregulated in the CNS [20] and in the PNS [36], which may contribute to the protection of neurons either by paracrine or autocrine mechanisms. Furthermore, EPO has been immune-detected in neurons, glial cells, and macrophages in EAE [20] and EAN [36] models. In EAE models, there is no doubt that neurons and glial cells exhibit an increased immunoreactivity of EPO, but the influence of EPO on macrophages requires further analysis.…”

“…In the case of spontaneous recovery from paralysis in rat EAE models, there is a predominance of M2 macrophages expressing arginase-1, which is a marker for the M2 phenotype [55]. Regarding its role in macrophages, EPO suppresses pro-inflammatory iNOS [20, 55] and negatively activates macrophages, which express TGF-beta [10]. This indicates that EPO plays an anti-inflammatory role in extra-erythropoietic organs [2], just as it does in EAE animals models.…”

“…During autoimmune disease in the CNS, neurons and glial cells would be affected by cytokines secreted from inflammatory cells as well as by oxidative stress [16]. Of these cells, some are destroyed while others persist via the expression of cytoprotective enzymes including heat shock proteins (HSP) [17, 18], osteopontin [19], and EPO [20]. Thus, a therapeutic target would be the decrease of pro-inflammatory cytokines and/or the increase of cytoprotective factors that have antioxidant and neuroprotective capacities.…”

Epobis is a Nonerythropoietic and Neuroprotective Agonist of the Erythropoietin Receptor with Anti-Inflammatory and Memory Enhancing Effects

“…This treatment caused a reduction in the clinical scores, a delay in the onset of the clinical signs, and a lower incidence of EAE [48]. In another study, EPO had the most pronounced effects on the clinical signs on EAE in rats, when the protein was administered prior to the onset of the clinical symptoms as compared to when the animals already had clinical signs at the onset of EPO administration [49]. Together, these observations suggest that the effects of Epobis on the progression of EAE could have been improved by administering the peptide earlier after immunization.…”