Recombinant human erythropoietin attenuates neuronal apoptosis and cognitive defects via JAK2/STAT3 signaling in experimental endotoxemia

Background: Septic encephalopathy is characterized by changes in mental status and an increase in neuronal apoptosis. Accumulating evidence has shown that recombinant human erythropoietin (rhEPO) protects brain against ischemia and hypoxia injury. However, whether rhEPO exerts neuroprotective effects on septic encephalopathy remains unclear. We designed the current study to evaluate possible neuroprotection of rhEPO in a model of sepsis. Methods: For this in vitro study, we determined hippocampal neuronal apoptosis by lactate dehydrogenase release, cell counting kit-8 assay, and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining after treatment with lipopolysaccharide. We transfected the signal transducer and activator of transcription 3 (STAT3) short hairpin RNA at 14 d in vitro for 48 h. For the in vivo study, we performed cecal ligation and peroration surgery. We detected the expression of phospho-Janus-activated kinase 2 (JAK2), total JAK2, phospho-STAT3, total STAT3, Bax and Bcl-XL by Western blot, and examined behavior using the Morris water maze. Results: Treatment with rhEPO reduces apoptosis and increases cell viability in lipopolysaccharide-treated neuronal cultures. In cecal ligation and peroration rats, rhEPO attenuated the inhibition of phospho-JAK2 and phospho-STAT3. In addition, rhEPO enhanced the expression of Bcl-XL, but depressed Bax, which was abolished by additional administration of inhibitor of JAK2/STAT3 signaling 2-cyano-3-(3,4-dihydroxyphenyl)-N-(benzyl)-2-propenamide, 2-cyano-3-(3,4-dihydroxyphenyl)-N-(phenylmethyl)-2-propenamide or (E)-3(6-bromopyridin-2-yl)-2-cyano-N-([S0-1-phenylethyl]acrylamide) in vivo, and was ameliorated by STAT3 short hairpin RNA transfection in vitro. Alternatively, we confirmed the neuronal protective effect of rhEPO by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelingstaining. For the Morris water maze study, rhEPO improved learning and memory disorders without an alternation in locomotor activity. Conclusions: These results indicated that rhEPO improves brain dysfunction by reducing neuronal apoptosis, and JAK2/STAT3 signaling is likely to be involved. Application of rhEPO may serve as a potential therapy for the treatment of septic encephalopathy. (C) 2013 Elsevier Inc. All rights reserved.