title: Amniotic fluid angiopoietin-1, angiopoietin-2, and soluble receptor tunica interna endothelial cell kinase-2 levels and regulation in normal pregnancy and intraamniotic inflammation-induced preterm birth.
abstract: BACKGROUND
  Angiopoietin-1 (Ang-1) and Ang-2 act selectively on endothelial cells by engaging the Tunica interna endothelial cell kinase-2 (Tie2) receptor. A soluble form of Tie2 (sTie2) blocks angiopoietin bioactivity.
  
  
  OBJECTIVE
  The aim of the study was to characterize changes and expression patterns of Ang-1, Ang-2, and sTie2 in amniotic fluid (AF) and placenta during human pregnancy and intraamniotic inflammation (IAI)-induced preterm birth.
  
  
  METHODS
  We conducted a cross-sectional study at a tertiary university hospital.
  
  
  METHODS
  AF levels of Ang-1, Ang-2, and sTie2 were evaluated in 176 women during second trimester (n = 40), third trimester (n = 37), and preterm labor (positive IAI, n = 50; negative IAI, n = 49). Placenta and cord blood of select women were analyzed.
  
  
  METHODS
  Ang-1, Ang-2, sTie2, and IL-6 were evaluated by ELISA. Real-time PCR measured Ang-1, Ang-2, and Tie2 placental mRNA levels. Placenta was immunostained for Ang-1 and Ang-2. Placental explant cultures were stimulated with lipopolysaccharide, Pam3Cys, and modulators of protein synthesis/secretion (cycloheximide, monensin, and brefeldin A).
  
  
  RESULTS
  In normal pregnancy, the levels and ratios of AF Ang-1, Ang-2, and sTie2 varied with gestational age (GA) (P < 0.001). PCR revealed corresponding changes in placental Ang-1 and Ang-2, but not Tie2, mRNA. IAI raised AF Ang-1, Ang-2, and sTie2 above the expected level for GA without affecting their placental mRNA. Ang-2 immunoreactivity appeared enhanced in areas of villous edema. AF Ang-2/Ang-1 ratio was an important determinant of cord blood IL-6 (P < 0.001). Ex-vivo, sTie2 release was increased by Golgi disrupting but not bacterial mimic agents.
  
  
  CONCLUSIONS
  Ang-1, Ang-2, and sTie2 are physiological constituents of AF that are GA and IAI regulated. Ang-2/Ang-1 ratio may play a role in modulating the fetal inflammatory response to IAI. Placental sTie2 shedding likely involves a Golgi-mediated mechanism.
authors.affiliation: Yale University School of Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, 333 Cedar Street, LLCI 804, New Haven, CT 06520, USA. catalin.buhimschi@yale.edu
authors.forename: Catalin S
authors.initials: CS
authors.lastname: Buhimschi
authors.forename: Vineet
authors.initials: V
authors.lastname: Bhandari
authors.forename: Antonette T
authors.initials: AT
authors.lastname: Dulay
authors.forename: Stephen
authors.initials: S
authors.lastname: Thung
authors.forename: Sonya S Abdel-
authors.initials: SS
authors.lastname: Razeq
authors.forename: Victor
authors.initials: V
authors.lastname: Rosenberg
authors.forename: Christina S
authors.initials: CS
authors.lastname: Han
authors.forename: Unzila A
authors.initials: UA
authors.lastname: Ali
authors.forename: Eduardo
authors.initials: E
authors.lastname: Zambrano
authors.forename: Guomao
authors.initials: G
authors.lastname: Zhao
authors.forename: Edmund F
authors.initials: EF
authors.lastname: Funai
authors.forename: Irina A
authors.initials: IA
authors.lastname: Buhimschi
mesh_terms: D000653:Amniotic Fluid / Q000378:metabolism*; D042683:Angiopoietin-1 / Q000235:genetics / Q000378:metabolism*; D042702:Angiopoietin-2 / Q000235:genetics / Q000378:metabolism*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D009924:Organ Culture Techniques; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000378:metabolism; D011263:Pregnancy Trimester, Third / Q000378:metabolism; D047928:Premature Birth / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012372:ROC Curve; D042787:Receptor, TIE-2 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D042683:Angiopoietin-1; D042702:Angiopoietin-2; D012333:RNA, Messenger; D042787:Receptor, TIE-2
references.citation: Lab Invest. 2003 Nov;83(11):1637-45
references.pmid: 14615417
references.citation: Science. 1997 Jul 4;277(5322):55-60
references.pmid: 9204896
references.citation: Pediatr Res. 2000 Jun;47(6):721-6
references.pmid: 10832728
references.citation: Recent Prog Horm Res. 2004;59:51-71
references.pmid: 14749497
references.citation: Nat Med. 2006 Feb;12(2):235-9
references.pmid: 16462802
references.citation: Science. 1987 Jan 23;235(4787):442-7
references.pmid: 2432664
references.citation: Oncogene. 2000 Sep 14;19(39):4549-52
references.pmid: 11002428
references.citation: Arterioscler Thromb Vasc Biol. 2007 Dec;27(12):2619-26
references.pmid: 17901375
references.citation: Rheumatol Int. 2009 Oct;29(12):1423-9
references.pmid: 19259676
references.citation: Dev Cell. 2002 Sep;3(3):411-23
references.pmid: 12361603
references.citation: BJOG. 2005 Feb;112(2):173-81
references.pmid: 15663581
references.citation: J Cell Sci. 2006 Sep 1;119(Pt 17):3551-60
references.pmid: 16895971
references.citation: Blood. 1999 Mar 15;93(6):1969-79
references.pmid: 10068670
references.citation: Biochem Biophys Res Commun. 2005 Jun 24;332(1):194-9
references.pmid: 15896317
references.citation: Mol Med. 2001 Sep;7(9):624-35
references.pmid: 11778652
references.citation: Acta Histochem. 2007;109(4):257-65
references.pmid: 17574656
references.citation: BJOG. 2009 Jan;116(2):257-67
references.pmid: 18947340
references.citation: J Clin Endocrinol Metab. 2002 Sep;87(9):4213-24
references.pmid: 12213874
references.citation: Circ Res. 1998 Aug 10;83(3):233-40
references.pmid: 9710115
references.citation: Nature. 1995 Jul 6;376(6535):70-4
references.pmid: 7596437
references.citation: Growth Factors. 2009 Dec;27(6):335-44
references.pmid: 19919521
references.citation: Placenta. 2009 Jan;30(1):79-87
references.pmid: 19010534
references.citation: J Pharmacol Exp Ther. 2005 Aug;314(2):738-44
references.pmid: 15870388
references.citation: Br J Haematol. 2007 Jun;137(6):560-8
references.pmid: 17451406
references.citation: J Clin Microbiol. 2009 Jan;47(1):38-47
references.pmid: 18971361
references.citation: Crit Care Med. 2007 Jan;35(1):199-206
references.pmid: 17110873
references.citation: Angiogenesis. 2001;4(2):123-31
references.pmid: 11806244
references.citation: PLoS Med. 2007 Jan;4(1):e18
references.pmid: 17227133
references.citation: Blood. 2005 Feb 15;105(4):1523-30
references.pmid: 15498854