Apoptosis of lymphoid tissues during sepsis is well documented and linked to the pathobiology of organ failure and death. In this study, we evaluated the effect of a single dose of recombinant erythropoietin (EPO) on thymic and splenic apoptosis in an endotoxic sepsis model. Young male Wistar rats were divided into 3 groups and administered intraperitoneally (IP) either normal saline; lipopolysaccharide (LPS) 10 mg/kg; or EPO (5000 U/kg) 30 min before lipopolysaccharide. Six hours following LPS administration animals were sacrificed. Apoptosis was assessed by hematoxylin-eosin staining, terminal deoxynucleotide transferase-mediated fluorescein-dUTP nick end labeling (TUNEL), and caspase-3 immunostaining. When compared with animals given LPS, animals pretreated with EPO displayed reduced splenic and thymic TUNEL positivity of 44±3 (p<0.05) and 1434 (p<0.05) nuclei per high power field (hpf), respectively. Caspase-3 positivity was also significantly reduced in the spleen and thymus, with 31±4 (p<0.05) and 93±3 (p<0.05) positive stained nuclei per hpf, respectively. Serum nitrite levels were elevated in animals given lipopolysaccharide. Pretreatment with EPO attenuated the increase in nitrite levels; however, this did not reach statistical significance. We conclude that a single dose of recombinant erythropoietin can reduce thymic and splenic apoptosis associated with lipopolysaccharide administration.
In the present study, we investigated whether erythropoietin (Epo) has a protective effect against cytotoxicity induced by interferon-gamma (IFN-
γ) and lipopolysaccharide (LPS) in primary rat oligodendrocyte cultures. The possible modulatory effect of erythropoietin on inducible nitric oxide synthase (iNOS) mRNA expression and nitrite production were also analyzed. Erythropoietin exerted a significant protective effect against IFN-γ and LPS-induced oligodendrocyte injury as determined by lactate dehydrogenase assay. Treatment with erythropoietin inhibited the expression of iNOS mRNA and nitrite production resulting from proinflammatory stimulation by IFN-γ and LPS. These results suggest that erythropoietin has protective effects against inflammatory oligodendrocyte injury in vitro and may play a protective role in neurological disorders characterized by oligodendrocyte death, such as multiple sclerosis.