Erythropoietin Attenuates Hyperoxia-Induced Cell Death by Modulation of Inflammatory Mediators and Matrix Metalloproteinases

Abstract

Oxygen toxicity appears to contribute to the pathogenesis of adverse neurological outcome in survivors of preterm birth. In infant rodent brains, hyperoxia triggers widespread apoptotic neurodegeneration, induces proinflammatory cytokines and inhibits growth factor signaling cascades. Since a tissue-protective effect has been observed for recombinant erythropoietin (rEpo), we hypothesized that rEpo would influence the expression of proinflammatory cytokines and matrix metalloproteinase (MMP)-2 and MMP-9. Six-day-old Wistar rats were exposed to 80% oxygen for 2–48 h and received 20,000 IU rEpo i.p. Sex-matched littermates kept in room air and injected with normal saline or rEpo served as controls. Treatment with rEpo significantly reduced hyperoxia-induced upregulation of the proinflammatory cytokines IL-1β and IL-18 in infant rodent brains on the mRNA and protein levels. In parallel, gelatin zymography in hyperoxia-treated immature rat brains revealed an upregulation of active MMP-2 which was reduced by concomitant rEpo treatment. Furthermore, hyperoxia induced upregulation of MMP-9 following 12 h of oxygen exposure and this was attenuated by rEpo treatment. Our results suggest that rEpo generates its protective effect against oxygen toxicity through a reduction of proinflammatory mediator levels.