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Limited protection against iron-induced lipid peroxidation by cord blood plasma
J H Lindeman1, E Houdkamp, E G Lentjes
1Department of Pediatrics, University Hospital, Leiden, The Netherlands.
Insights
Newborns have reduced plasma antioxidant capacity, making them vulnerable to iron-induced lipid peroxidation. This study highlights lower caeruloplasmin and transferrin levels in cord blood, increasing oxidative stress risk in infants.
Area of Science:
- Biochemistry
- Neonatal Physiology
- Oxidative Stress Research
Background:
- Lipid peroxidation is a damaging process implicated in various pathologies.
- Plasma contains antioxidant proteins like caeruloplasmin and transferrin that protect against iron-induced oxidative damage.
- Newborns may have altered antioxidant defenses compared to adults.
Purpose of the Study:
- To compare the antioxidant capacity of newborn (cord blood) and adult plasma against iron-induced lipid peroxidation.
- To investigate the roles of caeruloplasmin and transferrin in this protective mechanism in neonates.
- To assess the implications of reduced antioxidant capacity in newborns for oxygen toxicity.
Main Methods:
- Comparison of plasma samples from newborns and adults.
- Measurement of caeruloplasmin and transferrin concentrations and latent iron-binding capacity.
- Assessment of in vitro inhibition of iron-induced liposome peroxidation using ferroxidase and iron-binding antioxidant assays.
- Quantification of non-protein-bound iron using the bleomycin assay.
Main Results:
- Cord blood plasma showed significantly lower caeruloplasmin and transferrin levels and latent iron-binding capacity compared to adults.
- Many neonatal plasma samples lacked latent iron-binding capacity and contained non-protein-bound iron.
- Antioxidant activity in both ferroxidase and iron-binding assays was significantly reduced in newborns.
- Neonatal plasma's ability to inhibit peroxidation correlated positively with latent iron-binding capacity and negatively with detectable free iron.
Conclusions:
- Newborns exhibit diminished plasma antioxidant capacity, particularly concerning iron-induced lipid peroxidation.
- Lower levels of key iron-binding proteins like transferrin and caeruloplasmin contribute to this vulnerability.
- The reduced capacity of cord blood plasma to neutralize free iron may predispose infants to oxygen-related toxicity.
Abstract:
The ability of plasma from newborn babies (cord blood) and adults to inhibit iron-induced lipid peroxidation was compared. The caeruloplasmin and transferrin concentrations, and latent iron-binding capacity were lower in the babies (p less than 0.001). The plasma of many of the babies had no latent iron-binding capacity and contained non-protein-bound iron (measured by the bleomycin assay). The in vitro ability of plasma to inhibit iron-induced liposome peroxidation by either ferroxidase antioxidant activity (caeruloplasmin) or iron-binding antioxidant activity (transferrin) was measured. The antioxidant activity in both assays was decreased in the babies (p less than 0.001). The percentage inhibition of peroxidation in the iron-binding antioxidant assay correlated positively with the latent iron-binding capacity (p less than 0.001) and negatively with the presence of bleomycin-detectable iron (p less than 0.02) in the babies. This assay produced stimulation of peroxidation in 42% of the babies but none of the adults. The diminished capacity of cord blood plasma to prevent iron-induced lipid peroxidation may predispose the newborn baby to the toxic effects of oxygen.