Association of increased pulmonary interleukin-6 with the priming effect of intra-amniotic lipopolysaccharide on hyperoxic lung injury in a rat model of bronchopulmonary dysplasia.
BACKGROUND
The authors previously demonstrated the priming effect of intra-amniotic lipopolysaccharide (LPS) on hyperoxic lung injury in a rat model of bronchopulmonary dysplasia (BPD).


OBJECTIVE
To investigate the mechanism underlying this priming effect by determining biochemical profiles in a rat model of BPD.


METHODS
The rat model involved intra-amniotic LPS administration and postnatal hyperoxia (85%). The mRNA expressions of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2), basic fibroblast growth factor (bFGF), and transforming growth factor beta(1) (TGF-beta(1)), as well as the protein levels of IL-6, VEGF, and protein carbonyl in lung tissue were compared between the LPS plus hyperoxia, the LPS only, the hyperoxia only, and the control groups.


RESULTS
Morphometric analysis of lung tissues demonstrated that alveolarization was significantly inhibited only in the LPS plus hyperoxia group. IL-6 protein levels and its mRNA expression in the lungs were significantly increased only in the LPS plus hyperoxia group. Neither LPS nor hyperoxia increased IL-6 in the lungs independently. bFGF mRNA expression was significantly decreased in the LPS-treated groups. VEGF protein levels were significantly reduced by hyperoxia, whereas protein carbonyl levels were increased by intra-amniotic LPS or hyperoxia. No additional significant change to VEGF or protein carbonyl levels was produced by intra-amniotic LPS or hyperoxia. There were no significant differences in the mRNA expressions of VEGF, VEGFR-2, and TGF-beta(1).


CONCLUSIONS
The priming effect of intra-amniotic LPS on hyperoxic lung injury may be associated with IL-6 elevation in the lungs.
Kim
Do-Hyun
DH
Department of Pediatrics, Dongguk University Ilsan Hospital, Gyeonggi-do, Korea.
Choi
Chang Won
CW
Kim
Ee-Kyung
EK
Kim
Han-Suk
HS
Kim
Beyong Il
BI
Choi
Jung-Hwan
JH
Lee
Myong Jin
MJ
Yang
Eun Gyeong
EG
D000650:Amnion / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001997:Bronchopulmonary Dysplasia / Q000209:etiology / Q000378:metabolism*; D004195:Disease Models, Animal; D005346:Fibroblast Growth Factors / Q000032:analysis / Q000378:metabolism; D006801:Humans; D018496:Hyperoxia / Q000150:complications*; D007231:Infant, Newborn; D015850:Interleukin-6 / Q000032:analysis / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000633:toxicity*; D008168:Lung / Q000737:chemistry / Q000378:metabolism*; D050050:Protein Carbonylation; D011650:Pulmonary Alveoli / Q000254:growth & development / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000032:analysis / Q000378:metabolism
D015850:Interleukin-6; D008070:Lipopolysaccharides; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; D005346:Fibroblast Growth Factors; D040301:Vascular Endothelial Growth Factor Receptor-2