Over-expression of the thrombin receptor (PAR-1) in the placenta in preeclampsia: a mechanism for the intersection of coagulation and inflammation.
OBJECTIVE
Preeclampsia (PE) is characterized by excessive thrombin generation, which has been implicated in the multiple organ damage associated with the disease. The biological effects of thrombin on coagulation and inflammation are mediated by protease-activated receptor-1 (PAR-1), a G protein-coupled receptor. The aim of this study was to determine whether preterm PE is associated with changes in placental expression of PAR-1.


METHODS
This cross-sectional study included two groups matched for gestational age at delivery: (1) patients with preterm PE (<37 weeks of gestation; n = 26) and (2) a control group of patients with preterm labor without intra-amniotic infection (n = 26). Placental tissue microarrays were immunostained for PAR-1. Immunoreactivity of PAR-1 in the villous trophoblasts was graded as negative, weak-positive, or strong-positive.


RESULTS
(1) The proportion of cases with strong PAR-1 immunoreactivity was significantly higher in placentas of patients with PE than in placentas from the control group (37.5% (9/24) vs. 8.7% (2/23); p = 0.036, respectively). (2) PAR-1 immunoreactivity was found in the cellular compartments of the placental villous tree, mainly in villous trophoblasts and stromal endothelial cells. (3) PAR-1 was detected in 92.3% (24/26) of the placentas of women with PE and in 88.5% (23/26) of the placentas from the control group.


CONCLUSIONS
Placentas from pregnancies complicated by preterm PE had a significantly higher frequency of strong PAR-1 expression than placentas from women with spontaneous preterm labor. This observation is consistent with a role for PAR-1 as a mediator of the effect of thrombin on coagulation and inflammation in PE. We propose that the effects of thrombin in PE are due to increased thrombin generation and higher expression of PAR-1, the major receptor for this enzyme.
Erez
Offer
O
Perinatology Research Branch, NICHD, NIH, DHHS, Bethesda, Maryland, USA. warfiela@mail.nih.gov
Romero
Roberto
R
Kim
Sung-Su
SS
Kim
Jung-Sun
JS
Kim
Yeon Mee
YM
Wildman
Derek E
DE
Than
Nandor Gabor
NG
Mazaki-Tovi
Shali
S
Gotsch
Francesca
F
Pineles
Beth
B
Kusanovic
Juan Pedro
JP
Espinoza
Jimmy
J
Mittal
Pooja
P
Mazor
Moshe
M
Hassan
Sonia S
SS
Kim
Chong Jai
CJ
D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D007752:Obstetric Labor, Premature; D010920:Placenta / Q000276:immunology / Q000473:pathology*; D011225:Pre-Eclampsia / Q000276:immunology / Q000378:metabolism*; D011247:Pregnancy; D044463:Receptor, PAR-1 / Q000235:genetics*; D014327:Trophoblasts / Q000378:metabolism*
D044463:Receptor, PAR-1