Erythropoietin protects the developing brain from hyperoxia-induced cell death and proteome changes.
OBJECTIVE
Oxygen toxicity has been identified as a risk factor for adverse neurological outcome in survivors of preterm birth. In infant rodent brains, hyperoxia induces disseminated apoptotic neurodegeneration. Because a tissue-protective effect has been observed for recombinant erythropoietin (rEpo), widely used in neonatal medicine for its hematopoietic effect, we examined the effect of rEpo on hyperoxia-induced brain damage.


METHODS
Six-day-old C57Bl/6 mice or Wistar rats were exposed to hyperoxia (80% O(2)) or normoxia for 24 hours and received rEpo or normal saline injections intraperitoneally. The amount of degenerating cells in their brains was determined by DeOlmos cupric silver staining. Changes of their brain proteome were determined through two-dimensional electrophoresis and mass spectrometry. Western blot, enzyme activity assays and real-time polymerase chain reaction were performed for further analysis of candidate proteins.


RESULTS
Systemic treatment with 20,000 IE/kg rEpo significantly reduced hyperoxia-induced apoptosis and caspase-2, -3, and -8 activity in the brains of infant rodents. In parallel, rEpo inhibited most brain proteome changes observed in infant mice when hyperoxia was applied exclusively. Furthermore, brain proteome changes after a single systemic rEpo treatment point toward a number of mechanisms through which rEpo may generate its protective effect against oxygen toxicity. These include reduction of oxidative stress and restoration of hyperoxia-induced increased levels of proapoptotic factors, as well as decreased levels of neurotrophins.


CONCLUSIONS
These findings are highly relevant from a clinical perspective because oxygen administration to neonates is often inevitable, and rEpo may serve as an adjunctive neuroprotective therapy.
Kaindl
Angela M
AM
Department of Pediatric Neurology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany. angela.kaindl@charite.de
Sifringer
Marco
M
Koppelstaetter
Andrea
A
Genz
Kerstin
K
Loeber
Rebecca
R
Boerner
Constanze
C
Stuwe
Janine
J
Klose
Joachim
J
Felderhoff-Mueser
Ursula
U
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001238:Asphyxia Neonatorum / Q000188:drug therapy; D001921:Brain / Q000187:drug effects / Q000254:growth & development / Q000503:physiopathology; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D004195:Disease Models, Animal; D004921:Erythropoietin / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D018496:Hyperoxia / Q000150:complications* / Q000188:drug therapy* / Q000503:physiopathology; D007231:Infant, Newborn; D051379:Mice; D008810:Mice, Inbred C57BL; D009410:Nerve Degeneration / Q000188:drug therapy* / Q000209:etiology* / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018696:Neuroprotective Agents / Q000494:pharmacology / Q000627:therapeutic use; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000009:adverse effects; D010102:Oxygen Inhalation Therapy / Q000009:adverse effects; D020543:Proteome / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D018696:Neuroprotective Agents; D020543:Proteome; D004921:Erythropoietin; D020169:Caspases; D010100:Oxygen