Intra-amniotic endotoxin induces lung maturation by direct effects on the developing respiratory tract in preterm sheep.
OBJECTIVE
Our purpose was to determine whether improved preterm lung function caused by intraamniotic endotoxin treatment requires endotoxin entry into the respiratory tract.


METHODS
We assessed lung inflammation 2 days after intra-amniotic endotoxin (10 mg, Escherichia coli 055:B5) or saline solution in preterm lambs (123 days' gestation) that had undergone surgery to isolate the gastrointestinal or respiratory systems from the amniotic sac. In other sheep longer-term effects were assessed 7 days after we isolated the fetal respiratory tract and gave endotoxin or saline solution directly to the lungs or into the amniotic sac. We measured pulmonary inflammation, lung function, and surfactant 1 week after treatment (approximately 125 days).


RESULTS
Pulmonary inflammation was present after intra-amniotic endotoxin only if there was communication between the respiratory tract and the amniotic sac. Lung function was improved and surfactant was increased only in preterm lambs that received direct pulmonary endotoxin.


CONCLUSIONS
Endotoxin causes functional improvement of the preterm lung by direct effects on the developing respiratory system.
Moss
Timothy J M
TJ
School of Women's and Infants' Health, University of Western Australia, 35 Stirling Highway, Crawley WA, Perth, Australia. tmoss@cyllene.uwa.edu.au
Nitsos
Ilias
I
Kramer
Boris W
BW
Ikegami
Machiko
M
Newnham
John P
JP
Jobe
Alan H
AH
D000650:Amnion; D000818:Animals; D005314:Embryonic and Fetal Development; D004731:Endotoxins / Q000008:administration & dosage / Q000494:pharmacology*; D004926:Escherichia coli; D005260:Female; D005325:Fetal Organ Maturity / Q000187:drug effects; D005333:Fetus / Q000502:physiology; D007267:Injections; D008168:Lung / Q000196:embryology*; D011014:Pneumonia / Q000139:chemically induced; D011247:Pregnancy; D011663:Pulmonary Surfactants / Q000378:metabolism; D012137:Respiratory System / Q000196:embryology; D012756:Sheep
D004731:Endotoxins; D011663:Pulmonary Surfactants