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.
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.
Buhimschi
Catalin S
CS
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
Bhandari
Vineet
V
Dulay
Antonette T
AT
Thung
Stephen
S
Razeq
Sonya S Abdel-
SS
Rosenberg
Victor
V
Han
Christina S
CS
Ali
Unzila A
UA
Zambrano
Eduardo
E
Zhao
Guomao
G
Funai
Edmund F
EF
Buhimschi
Irina A
IA
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
D042683:Angiopoietin-1; D042702:Angiopoietin-2; D012333:RNA, Messenger; D042787:Receptor, TIE-2
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