title: Intra-amniotic LPS amplifies hyperoxia-induced airway hyperreactivity in neonatal rats.
abstract: BACKGROUND
  We previously showed that intra-amniotic lipopolysaccharide (LPS) amplifies alveolar hypoplasia induced by postnatal hyperoxia. We determined whether the priming effect of intra-amniotic LPS amplifies hyperoxia-induced airway hyperreactivity (AHR).
  
  
  METHODS
  LPS or normal saline was injected into the amniotic cavities of pregnant rats at the 20th day of gestation. After birth, rat pups were exposed to 60% O₂ or air for 14 d. On postnatal day 14, rat pups underwent forced oscillometry, which included a challenge with nebulized methacholine, and the lungs were harvested for morphological studies.
  
  
  RESULTS
  Hyperoxia significantly increased airway reactivity and decreased compliance. Intra-amniotic LPS further increased hyperoxia-induced AHR but did not further impair respiratory system compliance. Hyperoxia-induced changes in lung parenchymal and small airway morphology were not further altered by intra-amniotic LPS. However, combined exposure to intra-amniotic LPS and hyperoxia increased the proportion of degranulating mast cells in the hilar airways.
  
  
  CONCLUSIONS
  Intra-amniotic LPS amplified postnatal hyperoxia-induced AHR. This was associated with increased airway mast cell degranulation, which has previously been linked with hyperoxia-induced AHR. There were no morphologic changes of parenchyma or airways that would account for the LPS augmentation of hyperoxia-induced AHR.
authors.affiliation: Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, South Korea. choicw@snu.ac.kr
authors.forename: Chang Won
authors.initials: CW
authors.lastname: Choi
authors.forename: Beyong Il
authors.initials: BI
authors.lastname: Kim
authors.forename: Stanley N
authors.initials: SN
authors.lastname: Mason
authors.forename: Erin N
authors.initials: EN
authors.lastname: Potts-Kant
authors.forename: Mulugu V
authors.initials: MV
authors.lastname: Brahmajothi
authors.forename: Richard L
authors.initials: RL
authors.lastname: Auten
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D016535:Bronchial Hyperreactivity / Q000139:chemically induced*; D005260:Female; D018496:Hyperoxia / Q000139:chemically induced / Q000503:physiopathology*; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D008070:Lipopolysaccharides
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