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Presence of bleomycin-detectable free iron in the alveolar system of preterm infants
C E Gerber1, G Bruchelt, H Stegmann
1Department of Neonatology, Children's University Hospital, Rümelinstr. 23, Tübingen, D-72070, Germany. cagerber@med.uni-tuebingen.de
Insights
Free iron in bronchoalveolar secretions of preterm infants may increase the risk of hydroxyl radical formation, contributing to chronic lung disease (CLD). This finding highlights a potential mechanism in CLD development.
Area of Science:
- Neonatal Medicine
- Pulmonary Medicine
- Biochemistry
Background:
- Chronic lung disease (CLD) is a significant cause of long-term illness in preterm infants.
- Reactive oxygen species (ROS) are implicated in the development of CLD.
Purpose of the Study:
- To investigate the presence and role of free iron and iron-binding proteins in the bronchoalveolar secretions (BAS) of neonates.
- To assess the potential for hydroxyl radical formation in the alveolar space of preterm infants.
Main Methods:
- Analysis of bronchoalveolar secretions (BAS) from neonates for bleomycin-detectable free iron concentrations.
- Identification of iron-binding proteins (transferrin, ferritin, lactoferrin) in BAS.
- Electron paramagnetic resonance (EPR) used to detect hydroxyl radical (OH-radical) production in BAS with added iron and hydrogen peroxide.
Main Results:
- A high percentage (63-83%) of neonatal BAS contained significant free iron concentrations.
- Iron-binding proteins were detected in BAS, with slight differences in distribution between infants who developed CLD and those who recovered from respiratory distress syndrome (RDS).
- BAS demonstrated the capacity for hydroxyl radical production when exposed to iron and hydrogen peroxide, with minimal evidence of radical scavengers.
Conclusions:
- The presence of free iron in neonatal BAS suggests an elevated risk for hydroxyl radical formation in the alveolar space.
- This finding supports a potential mechanism linking iron-mediated oxidative stress to the pathogenesis of CLD in preterm infants.
- Further research into iron metabolism and antioxidant strategies may be beneficial for managing CLD in this population.
Abstract:
Chronic lung disease (CLD) is a major cause of long term morbidity in preterm infants. Reactive oxygen species (ROS) play an important role in the pathogenesis of CLD. We show that a high percentage (63 to 83%) of the investigated bronchoalveolar secretions (BAS) of neonates contain bleomycin-detectable free iron concentrations (0. 04-0.124 nmol/micrograms SC, median range). Beside the presence of redox-active iron several iron-binding proteins like transferrin, ferritin and lactoferrin were determined in BAS. Comparison of protein distribution within the first three days of life showed slight differences between the group of preterm infants who developed CLD and the neonates who recovered from RDS. Because of the existence of free iron we suggest a higher risk of hydroxyl radical formation in the alveolar space. In an artificial system with addition of iron and hydrogen peroxide we were able to demonstrate OH-radical production in BAS by electron paramagnetic resonance (EPR). OH-radical formation by H2O2 and iron in buffer solution was slightly enhanced in the presence of BAS, indicating the absence of OH-radical-scavengers in BAS.