title: Interleukin-18 system messenger RNA and protein expression in human endometrium during the menstrual cycle.
abstract: OBJECTIVE
  To investigate the IL-18 system, including IL-18, IL-18 receptor (IL-18R), IL-18 binding protein (IL-18BP), and IL-18 precursor (proIL-18), mRNA and protein expression in human endometrium during the menstrual cycle.
  
  
  METHODS
  Controlled study.
  
  
  METHODS
  Clinical and academic research setting in a university medical center.
  
  
  METHODS
  Human endometrium was obtained from surgical specimens of normal cycling women undergoing hysterectomy for benign reasons.
  
  
  METHODS
  A total of 24 human endometrium samples were obtained at proliferative and secretory phase from surgical specimens of normal cycling women undergoing hysterectomy. Quantitative competitive polymerase chain reaction (QC PCR) and immunohistochemistry were performed.
  
  
  METHODS
  The differences of IL-18 system mRNA and the ratio of antagonist to agonist in both proliferative and secretory phases of endometrium were analyzed.
  
  
  RESULTS
  Our results showed a complete IL-18 system, including mRNA expression and protein production in both proliferative and secretory phases of the endometrium. The QC PCR demonstrated that both IL-18 and IL-18R decreased and IL-18BP increased mRNA expression in human endometrium in secretory phase compared with proliferative phase. A positive correlation of IL-18 and IL-18R in human endometrium was demonstrated in proliferative phase but not in secretory phase. In addition, there is a significantly higher ratio of IL-18BP to IL-18 mRNA levels in secretory endometrium compared with proliferative phase endometrium (P<.05).
  
  
  CONCLUSIONS
  The expression and ratio of IL-18 antagonist to agonist may be responsible for embryo implantation.
authors.affiliation: Department of Obstetrics and Gynecology, Lin-Kou Medical Center, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan. hongyuan@cgmh.org.tw
authors.forename: Hong-Yuan
authors.initials: HY
authors.lastname: Huang
authors.forename: She-Hung
authors.initials: SH
authors.lastname: Chan
authors.forename: Hsing-Tse
authors.initials: HT
authors.lastname: Yu
authors.forename: Hsin-Shih
authors.initials: HS
authors.lastname: Wang
authors.forename: Chyong-Huey
authors.initials: CH
authors.lastname: Lai
authors.forename: Yung-Kuei
authors.initials: YK
authors.lastname: Soong
mesh_terms: D004717:Endometrium / Q000502:physiology*; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D020382:Interleukin-18 / Q000235:genetics / Q000378:metabolism*; D053727:Interleukin-18 Receptor alpha Subunit; D008597:Menstrual Cycle / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018123:Receptors, Interleukin / Q000235:genetics / Q000378:metabolism*; D053724:Receptors, Interleukin-18
chemical_list: C508572:IL18R1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D020382:Interleukin-18; D053727:Interleukin-18 Receptor alpha Subunit; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D053724:Receptors, Interleukin-18; C118370:interleukin-18 binding protein