title: Amniotic fluid sTREM-1 in normal pregnancy, spontaneous parturition at term and preterm, and intra-amniotic infection/inflammation.
abstract: OBJECTIVE
  Intra-amniotic infection/inflammation (IAI) is one of the most important mechanisms of disease in preterm birth. Triggering receptor expressed on myeloid cells (TREM)- 1 is a transmembrane glycoprotein expressed by neutrophils, macrophages and mature monocytes. TREM-1 is upregulated in biological fluids and tissues infected by Gram (+) and Gram (-) bacteria and fungi, amplifies the production of pro-inflammatory cytokines and chemokines, and its soluble form (sTREM-1) is released in the presence of infection. The aim of this study was to determine the effect of gestational age, parturition (term and preterm) and IAI in the amniotic fluid (AF) concentrations of sTREM-1.
  
  
  METHODS
  This cross-sectional study included 434 patients in the following groups: (1) mid-trimester of pregnancy (14-18 weeks, n = 38); (2) normal pregnant women at term with (n = 39) and without (n = 39) labor; (3) patients with spontaneous preterm labor (PTL) and intact membranes classified into: (a) PTL who delivered at term (n = 99); (b) PTL who delivered preterm (<37 weeks gestation) without IAI (n = 80); and (c) PTL with IAI (n = 59); and (4) women with preterm prelabor rupture of membranes (PROM) with (n = 40) and without (n = 40) IAI. The AF concentration of sTREM-1 was determined by enzyme-linked immunoassay. Non-parametric statistics were used for analyses.
  
  
  RESULTS
  (1) sTREM-1 was detected in all the AF samples; (2) the median AF sTREM-1 concentration at term was higher than in the mid-trimester (4277.6 pg/ml vs. 1140.4 pg/ml; p < 0.001); (3) among patients with PTL, the median AF sTREM-1 concentration was higher in patients with IAI than in those without IAI (6154.4 pg/ml vs. 3282.8 pg/ml; p < 0.001) and those with PTL who delivered at term (6154.4 pg/ml vs. 2794 pg/ml; p < 0.001); (4) patients with preterm PROM with IAI had a higher median AF sTREM-1 concentration than those without IAI (7893.1 pg/ml vs. 3386.6 pg/ml; p < 0.001); (5) no differences were observed in the median AF sTREM-1 concentration between patients with spontaneous labor at term and those at term not in labor (4712.4 pg/ml vs. 4277.6 pg/ml; respectively p = 0.4); and 6) an AF sTREM-1 concentration >or=6416 pg/ml (derived from a ROC curve) had a sensitivity of 72% and a specificity of 89% for the diagnosis of intra-amniotic infection.
  
  
  CONCLUSIONS
  sTREM-1 is a physiologic constituent of the AF, and its concentration: (1) is significantly elevated in the presence of IAI; (2) increases with advancing gestation; and (3) does not change in the presence of spontaneous labor at term. We propose that sTREM-1 play a role in the innate immune response against intra-amniotic infection.
authors: Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, USA. jkusanov@med.wayne.edu
authors: Juan Pedro
authors: JP
authors: Kusanovic
authors: Roberto
authors: R
authors: Romero
authors: Tinnakorn
authors: T
authors: Chaiworapongsa
authors: Pooja
authors: P
authors: Mittal
authors: Shali
authors: S
authors: Mazaki-Tovi
authors: Edi
authors: E
authors: Vaisbuch
authors: Offer
authors: O
authors: Erez
authors: Francesca
authors: F
authors: Gotsch
authors: Nandor Gabor
authors: NG
authors: Than
authors: Sam S
authors: SS
authors: Edwin
authors: Percy
authors: P
authors: Pacora
authors: Cristiano
authors: C
authors: Jodicke
authors: Lami
authors: L
authors: Yeo
authors: Sonia S
authors: SS
authors: Hassan
mesh_terms: D000328:Adult; D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry*; D002821:Chorioamnionitis / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000378:metabolism; D005865:Gestational Age; D006801:Humans; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000276:immunology; D036801:Parturition / Q000378:metabolism*; D011247:Pregnancy; D047928:Premature Birth / Q000378:metabolism*; D012372:ROC Curve; D011971:Receptors, Immunologic / Q000032:analysis* / Q000276:immunology; D012680:Sensitivity and Specificity; D000073871:Triggering Receptor Expressed on Myeloid Cells-1
chemical_list: D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; C408842:TREM1 protein, human; D000073871:Triggering Receptor Expressed on Myeloid Cells-1