Induction of lipid peroxidation of pulmonary surfactant by plasma of preterm babies.
Respiratory distress syndrome of the preterm baby is believed to be caused by a deficiency of pulmonary surfactant and leakage of plasma into the alveolar spaces. Since the two pathogenetic factors seem to be inter-related, we postulated that peroxidation of surfactant by plasma iron could be the linking mechanism. We obtained cord blood samples from 22 preterm babies (mean gestational age 32.2 [SD 2.7] weeks) and 24 term babies (40.1 [1.6] weeks), and venous blood samples from 18 healthy adults. No adult had detectable non-protein-bound iron in the plasma, but 10/21 (48%) preterm babies and 6/24 (25%) term babies had detectable concentrations (rate difference 23% [95% Cl -5 to 51%], p = 0.20). Transferrin and haptoglobin concentrations were higher and free haemoglobin concentrations lower in adults than in babies (p < 0.005). Only transferrin differed significantly between term and preterm babies. Plasma from all 18 adults and from 23 (96%) term babies inhibited iron-catalysed lipid peroxidation of pulmonary surfactant liposomes. By contrast, plasma from 11 (50%) preterm babies stimulated such peroxidation (difference in stimulation rate 46% [20-71%], p < 0.005 for preterm vs term babies); the ability to stimulate peroxidation was related to the presence of non-protein-bound iron (p < 0.001). Peroxidation decreased in the babies when apotransferrin was added to plasma and in all subjects when alpha-tocopherol was incorporated into the surfactant liposomes. Lipid peroxidation of surfactant may contribute to the pathogenesis of respiratory distress syndrome. Possible therapeutic approaches are increasing babies' iron-binding capacity by plasma transfusions and increasing the antioxidant capacity of commercial surfactant.
Moison
R M
RM
Department of Paediatrics, University Hospital of Leiden, The Netherlands.
Palinckx
J J
JJ
Roest
M
M
Houdkamp
E
E
Berger
H M
HM
D000328:Adult; D000818:Animals; D001798:Blood Proteins / Q000494:pharmacology*; D006801:Humans; D007231:Infant, Newborn / Q000097:blood; D007234:Infant, Premature / Q000097:blood*; D007501:Iron / Q000097:blood; D015227:Lipid Peroxidation / Q000187:drug effects*; D008081:Liposomes; D011663:Pulmonary Surfactants / Q000187:drug effects*; D013053:Spectrophotometry; D013552:Swine; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis
D001798:Blood Proteins; D008081:Liposomes; D011663:Pulmonary Surfactants; D017392:Thiobarbituric Acid Reactive Substances; D007501:Iron