title: Innate immune deficiency of extremely premature neonates can be reversed by interferon-γ.
abstract: BACKGROUND
  Bacterial sepsis is a major threat in neonates born prematurely, and is associated with elevated morbidity and mortality. Little is known on the innate immune response to bacteria among extremely premature infants.
  
  
  RESULTS
  We compared innate immune functions to bacteria commonly causing sepsis in 21 infants of less than 28 wks of gestational age, 24 infants born between 28 and 32 wks of gestational age, 25 term newborns and 20 healthy adults. Levels of surface expression of innate immune receptors (CD14, TLR2, TLR4, and MD-2) for Gram-positive and Gram-negative bacteria were measured in cord blood leukocytes at the time of birth. The cytokine response to bacteria of those leukocytes as well as plasma-dependent opsonophagocytosis of bacteria by target leukocytes was also measured in the presence or absence of interferon-γ. Leukocytes from extremely premature infants expressed very low levels of receptors important for bacterial recognition. Leukocyte inflammatory responses to bacteria and opsonophagocytic activity of plasma from premature infants were also severely impaired compared to term newborns or adults. These innate immune defects could be corrected when blood from premature infants was incubated ex vivo 12 hrs with interferon-γ.
  
  
  CONCLUSIONS
  Premature infants display markedly impaired innate immune functions, which likely account for their propensity to develop bacterial sepsis during the neonatal period. The fetal innate immune response progressively matures in the last three months in utero. Ex vivo treatment of leukocytes from premature neonates with interferon-γ reversed their innate immune responses deficiency to bacteria. These data represent a promising proof-of-concept to treat premature newborns at the time of delivery with pharmacological agents aimed at maturing innate immune responses in order to prevent neonatal sepsis.
authors.affiliation: Division of Intensive Care, University Hospitals of Geneva, Geneva, Switzerland. pierre.tissieres@bct.aphp.fr
authors.forename: Pierre
authors.initials: P
authors.lastname: Tissières
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Ochoda
authors.forename: Irène
authors.initials: I
authors.lastname: Dunn-Siegrist
authors.forename: Geneviève
authors.initials: G
authors.lastname: Drifte
authors.forename: Michel
authors.initials: M
authors.lastname: Morales
authors.forename: Riccardo
authors.initials: R
authors.lastname: Pfister
authors.forename: Michel
authors.initials: M
authors.lastname: Berner
authors.forename: Jérôme
authors.initials: J
authors.lastname: Pugin
mesh_terms: D001835:Body Weight; D002460:Cell Line; D005260:Female; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology; D005434:Flow Cytometry; D005865:Gestational Age; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology*; D052577:Infant, Extremely Low Birth Weight / Q000276:immunology*; D007231:Infant, Newborn; D007234:Infant, Premature / Q000276:immunology*; D007371:Interferon-gamma / Q000627:therapeutic use*; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D010587:Phagocytosis / Q000502:physiology; D011247:Pregnancy; D011971:Receptors, Immunologic / Q000378:metabolism; D018805:Sepsis / Q000188:drug therapy* / Q000276:immunology*; D018709:Statistics, Nonparametric
chemical_list: D011971:Receptors, Immunologic; D007371:Interferon-gamma