title: Association of neutrophil extracellular traps with endometriosis-related chronic inflammation.
abstract: OBJECTIVE
  To study if neutrophil extracellular traps (NETs) are present in the peritoneal fluid of endometriosis patients. NETs play a crucial role in fighting against microorganisms. However, exaggerated NET production may lead to tissue damage in their vicinity in pathological conditions. Our study evaluates the presence of NETs in endometriosis peritoneal fluid.
  
  
  METHODS
  Peritoneal fluid (PF) was collected in a case-control study from 52 women, who underwent either diagnostic or operative laparoscopy. The control group consisted of 17 women with infertility, chronic pelvic pain, simple or functional cysts or irregular bleeding. The endometriosis group, altogether 35 patients, comprised 19 patients with stage I and II and 16 patients with stage III and IV endometriosis. First we tested whether the PF is able to stimulate NET production. Neutrophils from healthy volunteers were treated with the PF of endometriosis patients and controls and NETs were detected with Sytox orange extracellular DNA dye and immunofluorescence microscopy. Then we evaluated if NETs were already present in the collected PF using the specific myeloperoxidase (MPO)-DNA capture ELISA method, based on the MPO associated with the NET scaffold.
  
  
  RESULTS
  The PF of endometriosis patients did not stimulate NET release from healthy granulocytes. However, pre-existent NETs could be detected in 17 endometriosis patients out of 35 (49%). In contrary, in the control group NETs were present in only 3 patients out of 17 (18%), (p=0.03, OR: 4.4). Moreover, the quantification of NETs showed a significantly higher amount of NETs in endometriosis compared to the controls (0.097 vs. 0.02, p=0.04).
  
  
  CONCLUSIONS
  This is the first study, which evaluated and described the presence of NETs in the PF of endometriosis patients. Our study shows, that NETs may be involved in the complex pathophysiology of endometriosis.
authors.affiliation: Department of Obstetrics and Gynaecology, Justus-Liebig-University, 35392 Giessen, Germany. Electronic address: eniko.berkes@gyn.med.uni-giessen.de.
authors.forename: Eniko
authors.initials: E
authors.lastname: Berkes
authors.affiliation: Department of Obstetrics and Gynaecology, Justus-Liebig-University, 35392 Giessen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Oehmke
authors.affiliation: Department of Obstetrics and Gynaecology, Justus-Liebig-University, 35392 Giessen, Germany.
authors.forename: Hans-R
authors.initials: HR
authors.lastname: Tinneberg
authors.affiliation: Institute of Biochemistry, Medical School, Justus-Liebig-University, 35392 Giessen, Germany.
authors.forename: Klaus T
authors.initials: KT
authors.lastname: Preissner
authors.affiliation: Institute of Biochemistry, Medical School, Justus-Liebig-University, 35392 Giessen, Germany.
authors.forename: Mona
authors.initials: M
authors.lastname: Saffarzadeh
mesh_terms: D000328:Adult; D001202:Ascitic Fluid / Q000276:immunology* / Q000473:pathology; D016022:Case-Control Studies; D004715:Endometriosis / Q000276:immunology* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D065206:Extracellular Traps; D005260:Female; D006801:Humans; D007249:Inflammation / Q000276:immunology* / Q000473:pathology; D009504:Neutrophils / Q000473:pathology*
keywords: Endometriosis; Inflammation; Innate immunity; Neutrophil extracellular trap; Neutrophils