Postnatal lung inflammation increased by ventilation of preterm lambs exposed antenatally to Escherichia coli endotoxin.
Chorioamnionitis resulting in exposure of the fetal lung to inflammation is frequent before preterm delivery. The initiation of mechanical ventilation in the preterm recruits granulocytes to the lungs and increases proinflammatory cytokine expression in the lungs. We hypothesized that when the prematurely born newborn with chorioamnionitis was ventilated, inflammation would increase. Therefore, we asked whether inflammatory exposure to the fetal lung caused by intra-amniotic endotoxin (10 mg, Escherichia coli 055:beta 5) given at 100 d gestation would alter the inflammatory responses to the mechanical ventilation in surfactant-treated preterm lambs delivered at 130 d gestation. Cells in alveolar washes, proinflammatory cytokine expression, and surfactant protein mRNA expression were not different for saline and endotoxin exposed lambs that were not ventilated. The endotoxin- and saline-exposed control animals had similar lung function for 6 h of ventilation. Bronchoalveolar lavage fluid from the ventilated and antenatal endotoxin-exposed animals contained 5.7 times more monocytes, 12 times more lymphocytes, and a nonsignificant increase in neutrophils. Cells from the bronchoalveolar lavage fluid expressed 3-fold more IL-6 and IL-8 mRNA than did cells from the saline exposed comparison animals. An antenatal exposure of the fetal lung to endotoxin enhanced the subsequent inflammatory response of the ventilated preterm lung.
Cincinnati Children's Hospital Medical Center, Division of Pulmonary Biology, Cincinnati, Ohio 45229-3039, USA. machiko.ikegami@chmcc.org
Machiko
M
Ikegami
Alan H
AH
Jobe
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004731:Endotoxins / Q000633:toxicity*; D005321:Extraembryonic Membranes / Q000276:immunology / Q000473:pathology; D005260:Female; D005865:Gestational Age; D007249:Inflammation; D007962:Leukocytes / Q000276:immunology; D008168:Lung / Q000196:embryology / Q000276:immunology* / Q000502:physiology; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011663:Pulmonary Surfactants / Q000378:metabolism; D011897:Random Allocation; D012121:Respiration, Artificial / Q000009:adverse effects*; D015656:Respiratory Mechanics; D012756:Sheep
D016207:Cytokines; D004731:Endotoxins; D011663:Pulmonary Surfactants; C044101:endotoxin, Escherichia coli