title: Blood soluble interleukin 1 receptor accessory protein levels are consistently low throughout the menstrual cycle of women with endometriosis.
abstract: BACKGROUND
  A deficiency in the counter-regulatory mechanisms of interleukin 1 (IL1) may play a significant role in endometriosis pathogenesis and associated chronic inflammation. The aim of this study was to investigate peripheral blood levels of soluble IL1 receptor accessory protein (sIL1RAP), a potent natural inhibitor of IL1, in women with and without endometriosis.
  
  
  METHODS
  Peripheral blood samples were collected from women with endometriosis (n = 47) consulting for infertility, pelvic pain or tubal ligation, in whom the disease was diagnosed at laparoscopy. Control healthy women (n = 27) were requesting tubal ligation or reanastomosis and had no visible evidence of endometriosis at laparoscopy. sIL1RAP levels were determined by ELISA, whereas estradiol (E2) and progesterone (P4) levels were determined by competitive immunoassays.
  
  
  RESULTS
  sIL1RAP levels were significantly decreased in women with early endometriosis stages compared to controls (p < 0.05) and markedly during the proliferative phase of the menstrual cycle (p < 0.001). Actually, while sIL1RAP were significantly increased in the proliferative compared to the secretory phase in normal women (p < 0.0001) and peaked at the end of this phase, sIL1RAP remained consistently low and showed non-significant variations throughout the menstrual cycle in women with endometriosis.
  
  
  CONCLUSIONS
  Lower circulating levels of sIL1RAP points to a significant impairment in the counter-regulatory mechanisms of IL1, which in view of the cytokine's potent inflammatory and growth-promoting properties may play a significant role in the pathophysiology of endometriosis.
authors.forename: Nadège
authors.initials: N
authors.lastname: Michaud
authors.forename: Mahera
authors.initials: M
authors.lastname: Al-Akoum
authors.affiliation: Centre Hospitalier Universitaire de Québec, Hôpital Saint-François d'Assise, 10, rue de l'Espinay, Québec D0-711, Canada. ali.akoum@crsfa.ulaval.ca.
authors.forename: Ali
authors.initials: A
authors.lastname: Akoum
mesh_terms: D000328:Adult; D017398:Alternative Splicing; D015536:Down-Regulation; D004715:Endometriosis / Q000097:blood* / Q000503:physiopathology; D004797:Enzyme-Linked Immunosorbent Assay; D004958:Estradiol / Q000097:blood; D005260:Female; D005298:Fertility; D005498:Follicular Phase; D006801:Humans; D007247:Infertility, Female / Q000209:etiology; D053577:Interleukin-1 Receptor Accessory Protein / Q000097:blood* / Q000737:chemistry / Q000235:genetics; D008183:Luteal Phase; D008597:Menstrual Cycle; D016011:Normal Distribution; D017699:Pelvic Pain / Q000209:etiology; D011374:Progesterone / Q000097:blood; D011792:Quebec; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012995:Solubility
chemical_list: C507765:IL1RAP protein, human; D053577:Interleukin-1 Receptor Accessory Protein; D011374:Progesterone; D004958:Estradiol