title: Expression of aminopeptidase N in human endometrium and regulation of its activity by estrogen.
abstract: OBJECTIVE
  To determine whether aminopeptidase N (APN) regulates the cycle-dependent bioavailability of interleukin-8 (IL-8) in the endometrium.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  University medical center.
  
  
  METHODS
  Women without endometrial pathology from the proliferative (n = 25) or secretory (n = 18) phase of the menstrual cycle.
  
  
  METHODS
  We first immunolocalized APN in the endometrium using an anti-APN antibody. We then determined the regulation of APN kinetic activity by sex steroids in endometrial stromal cell cultures.
  
  
  METHODS
  Expression of APN in human endometrium throughout the menstrual cycle. Regulation of APN activity by estradiol and progesterone in cultured endometrial stromal cells.
  
  
  RESULTS
  Immunohistochemistry of endometrial sections revealed staining of endometrial stroma throughout the menstrual cycle. There was no detectable staining in glandular cells. The expression of APN as detected by immunohistochemistry was significantly lower in the early proliferative phase. In cultured cells, estradiol inhibited APN activity in a concentration-dependent manner. Progesterone did not have a significant effect.
  
  
  CONCLUSIONS
  Stromal localization of APN in endometrium may explain the epithelial rather than stromal presence of IL-8 in vivo. Decreased expression of APN may increase IL-8 bioavailability thus contributing to angiogenesis and polymorphonuclear leukocyte chemotaxis in early proliferative phase.
authors.affiliation: Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06520-8063, USA.
authors.forename: E
authors.initials: E
authors.lastname: Seli
authors.forename: L M
authors.initials: LM
authors.lastname: Senturk
authors.forename: O M
authors.initials: OM
authors.lastname: Bahtiyar
authors.forename: U A
authors.initials: UA
authors.lastname: Kayisli
authors.forename: A
authors.initials: A
authors.lastname: Arici
mesh_terms: D018826:CD13 Antigens / Q000378:metabolism*; D002478:Cells, Cultured; D004717:Endometrium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000502:physiology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016209:Interleukin-8 / Q000494:pharmacology; D008597:Menstrual Cycle / Q000502:physiology; D011374:Progesterone / Q000494:pharmacology; D011446:Prospective Studies; D014018:Tissue Distribution
chemical_list: D004967:Estrogens; D016209:Interleukin-8; D011374:Progesterone; D004958:Estradiol; D018826:CD13 Antigens