title: Innate immune activation in neonatal tracheal aspirates suggests endotoxin-driven inflammation.
abstract: BACKGROUND
  Tracheal aspirates (TAs) from critically ill neonates accumulate bacterial endotoxin and demonstrate mobilization of endotoxin-binding proteins, but the potential bioactivity of endotoxin in TAs is unknown. We characterized innate immune activation in TAs of mechanically ventilated neonates.
  
  
  METHODS
  Innate immune activation in TAs of mechanically ventilated neonates was characterized using a targeted 84-gene quantitative real-time (qRT) PCR array. Protein expression of cytokines was confirmed by multiplex assay. Expression and localization of the endotoxin-inducible antimicrobial protein Calgranulin C (S100A12) was assessed by flow cytometry. Endotoxin levels were measured in TA supernatants using the Limulus amoebocyte lysate assay.
  
  
  RESULTS
  Analyses by qRT-PCR demonstrated expression of pattern recognition receptors, Toll-like receptor-nuclear factor κB and inflammasome pathways, cytokines/chemokines and their receptors, and anti-infective proteins in TA cells. Endotoxin positivity increased with postnatal age. As compared with endotoxin-negative TAs, endotoxin-positive TAs demonstrated significantly greater tumor necrosis factor (TNF), interleukin (IL)-6, IL-10, and serpin peptidase inhibitor, clade E, member 1 (SERPINE1) mRNA, and IL-10, TNF, and IL-1β protein. Expression of S100A12 protein was localized to TA neutrophils.
  
  
  CONCLUSIONS
  Correlation of endotoxin with TA inflammatory responses suggests endotoxin bioactivity and the possibility that endotoxin antagonists could mitigate pulmonary inflammation and its sequelae in this vulnerable population.
authors.affiliation: Department of Medicine, Children's Hospital Boston, Massachusetts, USA.
authors.forename: Katheryn E
authors.initials: KE
authors.lastname: Nathe
authors.forename: Christy J
authors.initials: CJ
authors.lastname: Mancuso
authors.forename: Richard
authors.initials: R
authors.lastname: Parad
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Van Marter
authors.forename: Camilia R
authors.initials: CR
authors.lastname: Martin
authors.forename: Liat
authors.initials: L
authors.lastname: Stoler-Barak
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Philbin
authors.forename: Michele F
authors.initials: MF
authors.lastname: Phillips
authors.forename: Christine D
authors.initials: CD
authors.lastname: Palmer
authors.forename: Ofer
authors.initials: O
authors.lastname: Levy
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D016207:Cytokines / Q000378:metabolism; D004731:Endotoxins / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology*; D007231:Infant, Newborn / Q000276:immunology*; D008033:Limulus Test; D008856:Microscopy, Fluorescence; D060888:Real-Time Polymerase Chain Reaction; D012121:Respiration, Artificial / Q000009:adverse effects*; D009418:S100 Proteins / Q000378:metabolism*; D000067616:S100A12 Protein; D014132:Trachea / Q000378:metabolism* / Q000382:microbiology
chemical_list: D016207:Cytokines; D004731:Endotoxins; D009418:S100 Proteins; D000067616:S100A12 Protein; C090441:S100A12 protein, human