Elevated Free Radical Products in the Cerebrospinal Fluid of VLBW Infants with Cerebral White Matter Injury

Abstract

Free radical mediated cellular injury has been hypothesized to play a key role in the pathogenesis of white matter injury in the premature infant, although direct evidence is lacking. Between April 1999 and May 2001, 22 very low birthweight infants, 30 term infants, and 17 adults had samples of cerebrospinal fluid (CSF) collected for clinical indications. Only CSF samples without any evidence of meningeal inflammation were analyzed for the levels of the lipid peroxidation products, 8-isoprostane and malondialdehyde (MDA), and protein carbonyls as a measure of protein oxidation. Chlorotyrosine was monitored as a measure of neutrophil oxidative activity. In the premature infants with subsequent evidence of white matter injury on magnetic resonance imaging at term, there was a significant elevation in the CSF level of protein carbonyls in comparison with the level in healthy premature infants, term infants, and adult controls (all p < 0.001). A significant difference in the levels of the lipid peroxidation products, 8-isoprostane and MDA, was apparent between premature infants with white matter injury and adult controls (isoprostanes p = 0.02, MDA p = 0.014). There was a trend toward higher levels of 8-isoprostane in the premature infants with white matter injury in comparison with those without white matter injury (p = 0.08), with 5 of the 14 infants with white matter injury having levels that were more than 10-fold higher than the top of the adult range. There was no significant difference in the level of chlorotyrosines among any of the groups. These preliminary data provide evidence of an association of elevated oxidative products during the evolution of white matter injury in the human premature infant.