title: Maternal circulating leukocytes display early chemotactic responsiveness during late gestation.
abstract: BACKGROUND
  Parturition has been widely described as an immunological response; however, it is unknown how this is triggered. We hypothesized that an early event in parturition is an increased responsiveness of peripheral leukocytes to chemotactic stimuli expressed by reproductive tissues, and this precedes expression of tissue chemotactic activity, uterine activation and the systemic progesterone/estradiol shift.
  
  
  METHODS
  Tissues and blood were collected from pregnant Long-Evans rats on gestational days (GD) 17, 20 and 22 (term gestation). We employed a validated Boyden chamber assay, flow cytometry, quantitative real time-polymerase chain reaction, and enzyme-linked immunosorbent assays.
  
  
  RESULTS
  We found that GD20 maternal peripheral leukocytes migrated more than those from GD17 when these were tested with GD22 uterus and cervix extracts. Leukocytes on GD20 also displayed a significant increase in chemokine (C-C motif) ligand 2 (Ccl2) gene expression and this correlated with an increase in peripheral granulocyte proportions and a decrease in B cell and monocyte proportions. Tissue chemotactic activity and specific chemokines (CCL2, chemokine (C-X-C motif) ligand 1/CXCL1, and CXCL10) were mostly unchanged from GD17 to GD20 and increased only on GD22. CXCL10 peaked on GD20 in cervical tissues. As expected, prostaglandin F2α receptor and oxytocin receptor gene expression increased dramatically between GD20 and 22. Progesterone concentrations fell and estradiol-17β concentrations increased in peripheral serum, cervical and uterine tissue extracts between GD20 and 22.
  
  
  CONCLUSIONS
  Maternal circulating leukocytes display early chemotactic responsiveness, which leads to their infiltration into the uterus where they may participate in the process of parturition.
authors: Department of Obstetrics and Gynecology, Pediatrics and Physiology, University of Alberta, Edmonton T6G 2S2, Canada.
authors: Nardhy
authors: N
authors: Gomez-Lopez
authors: Satomi
authors: S
authors: Tanaka
authors: Zoya
authors: Z
authors: Zaeem
authors: Gerlinde A
authors: GA
authors: Metz
authors: David M
authors: DM
authors: Olson
mesh_terms: D000818:Animals; D002584:Cervix Uteri / Q000166:cytology / Q000378:metabolism*; D018925:Chemokines / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte / Q000276:immunology / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D004958:Estradiol / Q000032:analysis; D005260:Female; D015870:Gene Expression; D007962:Leukocytes / Q000378:metabolism*; D036801:Parturition / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D011374:Progesterone / Q000032:analysis; D051381:Rats; D020318:Rats, Long-Evans; D018045:Receptors, Oxytocin / Q000097:blood / Q000235:genetics; D011982:Receptors, Prostaglandin / Q000097:blood / Q000235:genetics
chemical_list: D018925:Chemokines; D018045:Receptors, Oxytocin; D011982:Receptors, Prostaglandin; D011374:Progesterone; D004958:Estradiol