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Development of pulmonary lipophilic antioxidants and peroxidizable lipids during lung maturation
M Rüdiger1, R Haupt, R R Wauer
1Department of Neonatology, Charité/Humboldt-University, Berlin, Germany.
Insights
Preterm infants have lower polyunsaturated fatty acids (PUFA) in lung surfactant, increasing oxidative lung injury risk. This is due to reduced PUFA levels, not antioxidant imbalance, impacting lung maturation.
Area of Science:
- Biochemistry
- Neonatal Physiology
- Pulmonary Medicine
Background:
- Lung maturation is crucial for neonatal adaptation.
- Oxidative stress is a significant risk factor for lung injury in preterm infants.
- Lipid composition of pulmonary surfactant plays a role in lung function and protection.
Purpose of the Study:
- To investigate the correlation between fetal lung lipid and antioxidant concentrations and lung maturation.
- To compare lung effluent lipid profiles in preterm infants with Respiratory Distress Syndrome (RDS) and healthy term infants.
Main Methods:
- Measurement of palmitic/stearic acid (P/S) ratio in amniotic fluid.
- Quantification of polyunsaturated fatty acids (PUFA), cholesterol, vitamin E, and plasmalogens in amniotic fluid and lung effluent.
- Comparison of PUFA/S ratio in lung effluent between preterm and term infants.
Main Results:
- Plasmalogens, PUFA, total and free cholesterol concentrations significantly increase with lung maturation (P/S ratio).
- No correlation was found between vitamin E levels and lung maturation.
- Preterm infants with RDS exhibited a significantly lower PUFA/S ratio in lung effluent compared to term infants.
Conclusions:
- The increased susceptibility of preterm infants to oxidative lung injury is attributed to lower amounts of PUFA-containing surfactant lipids, not an unfavorable lipid antioxidant ratio.
- Higher PUFA levels in lung surfactant may offer protection against oxidative lung damage, as suggested by animal studies.
Abstract:
The objective of this article is to test whether the concentration of potentially oxidizable lipids (polyunsaturated fatty acids [PUFA], total and free cholesterol) and lipophilic antioxidants (plasmalogens, vitamin E) in the fetal lung correlate with lung maturation (P/S ratio). In amniotic fluid palmitic/stearic acid (P/S) ratio, concentrations of PUFA, total and free cholesterol, vitamin E, and plasmalogens were measured. Ratio of PUFA to stearic acid (PUFA/S ratio) was determined in lung effluent of 15 preterm infants with IRDS and compared with values from 15 term healthy infants. Concentrations of plasmalogens, PUFA, total and free cholesterol increase significantly with increasing P/S ratio. No correlation of vitamin E with lung maturation has been found. The PUFA/S ratio is significantly lower in lung effluent of preterm (0.79 +/- 0.27) when compared with term infants (2.02 +/- 0.38). Our results suggest that the higher susceptibility of preterm infants for oxidative lung injury is not caused by an unfavorable ratio of oxidizable lipids to lipophilic antioxidants in surfactant, but rather by a lower amount of PUFA containing surfactant lipids. Our results are in accordance with data from Sosenko et al. who have shown that high levels of PUFA in the rat lung have a protective effect against oxygen-induced lung damage.