title: Depletion of polymorphonuclear leukocytes has no effect on preterm delivery in a mouse model of Escherichia coli-induced labor.
abstract: OBJECTIVE
  The objective of the study was to investigate the role of polymorphonuclear leukocytes (PMNs) in a mouse model of Escherichia coli-induced labor.
  
  
  METHODS
  Intraperitoneal injection of rabbit antimouse PMN antiserum or control was performed in CD-1 mice 29 hours and 5 hours prior to laparotomy and intrauterine injection of either killed E coli or phosphate-buffered saline on day 14.5 of pregnancy. Preterm delivery was defined as delivery of at least 1 pup within 48 hours. Circulating leukocyte counts were determined manually or by flow cytometry at the time of surgery and 8, 24, and 48 hours afterward. Maternal and fetal tissues were analyzed in a separate group of animals 8 hours after surgery.
  
  
  RESULTS
  Pretreatment with anti-PMN antiserum significantly decreased the numbers of circulating leukocytes and the proportion of neutrophils among all leukocytes by 70-80% at surgery and at least 8 hours thereafter. Neutrophil depletion significantly reduced 2 markers of neutrophil activation in the uterus and placenta (neutrophil elastase and myeloperoxidase activity) and neutrophil infiltration into gestational tissues in bacterially treated animals to baseline (control) levels but did not affect preterm birth rates. The large E coli-induced increases in uterine inflammatory markers (interleukin-1β, tumor necrosis factor, chemokine ligand-5, cyclooxygenase-2) were not affected or were only minimally affected by neutrophil depletion.
  
  
  CONCLUSIONS
  Although PMN antiserum reduces both neutrophil number and activity, it does not diminish sensitivity to bacterially induced delivery or meaningfully alter the expression of inflammatory markers in the mouse model. Preterm birth and inflammation in this model are not likely to depend on neutrophil function.
authors.affiliation: Department of Obstetrics and Gynecology, NorthShore University HealthSystem, Evanston, IL.
authors.forename: Yana
authors.initials: Y
authors.lastname: Filipovich
authors.affiliation: Department of Obstetrics and Gynecology, NorthShore University HealthSystem, Evanston, IL.
authors.forename: Varkha
authors.initials: V
authors.lastname: Agrawal
authors.affiliation: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Crawford
authors.affiliation: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO.
authors.forename: Philip
authors.initials: P
authors.lastname: Fitchev
authors.affiliation: Department of Obstetrics and Gynecology, NorthShore University HealthSystem, Evanston, IL.
authors.forename: Xiaowu
authors.initials: X
authors.lastname: Qu
authors.affiliation: Department of Obstetrics and Gynecology, NorthShore University HealthSystem, Evanston, IL.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Klein
authors.affiliation: Department of Obstetrics and Gynecology, NorthShore University HealthSystem, Evanston, IL; Pritzker School of Medicine, University of Chicago, Chicago, IL. Electronic address: ehirsch@northshore.org.
authors.forename: Emmet
authors.initials: E
authors.lastname: Hirsch
mesh_terms: D000818:Animals; D016207:Cytokines; D004195:Disease Models, Animal; D004927:Escherichia coli Infections / Q000097:blood*; D005260:Female; D015870:Gene Expression; D051379:Mice; D008815:Mice, Inbred Strains; D023421:Models, Animal; D009504:Neutrophils / Q000502:physiology*; D007752:Obstetric Labor, Premature / Q000097:blood* / Q000382:microbiology / Q000503:physiopathology*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000097:blood*
chemical_list: D016207:Cytokines
keywords: infection; mouse; neutrophils; polymorphonuclear leukocytes; preterm labor