Endometrial inhibin/activin beta-B subunit expression is related to decidualization and is reduced in tubal ectopic pregnancy.
BACKGROUND
Ectopic pregnancy is common but remains difficult to diagnose accurately. There is no serum test to differentiate ectopic from intrauterine gestation.


OBJECTIVE
Our objective was to investigate differential gene expression in decidualized endometrium of ectopic pregnancy.


METHODS
Tissue and serum analysis informed by microarray study was performed.


METHODS
The study was performed at a large United Kingdom teaching hospital.


METHODS
Women undergoing surgical termination of pregnancy (n = 8), evacuation of uterus for miscarriage (n = 6), and surgery for tubal ectopic pregnancy (n = 11) were included in the study. Endometrium was collected from normally cycling women undergoing hysterectomy.


METHODS
Decidualized endometrium was subjected to microarray analysis, morphological assessment, and immunohistochemistry. Endometrial stromal fibroblasts were cultured in the presence of decidualizing stimuli.


METHODS
Differential expression of potentially secreted molecules was calculated.


RESULTS
Inhibin/activin beta-B expression was lower in decidualized endometrium from ectopic pregnancies when compared with that of ongoing pregnancies (P < 0.01) or miscarriages (P < 0.01). The localization of the beta-B subunit was more marked in decidualized than nondecidualized stroma. Decidualization of stromal fibroblasts in vitro was associated with increased beta-B expression (P < 0.05). Endometrial stroma of ectopic pregnancies was less decidualized morphologically (P < 0.05), with lower prolactin (P < 0.01) and IGF binding protein-1 (P < 0.005) expression. Serum activin B was lower in ectopic pregnancies (P < 0.005) than in intrauterine pregnancies, whereas there was no difference in progesterone concentrations.


CONCLUSIONS
Despite similar concentrations of progesterone, the endometrium of ectopic pregnancies is less decidualized than intrauterine pregnancies. Expression of the beta-B subunit is related to decidualization and can be detected in the circulation as activin B. Serum activin B concentrations are lower in ectopic pregnancy.
Horne
A W
AW
Obstetrics and Gynaecology, University of Edinburgh, Simpson Centre for Reproductive Health, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh, United Kingdom. andrew.horne@ed.ac.uk
van den Driesche
S
S
King
A E
AE
Burgess
S
S
Myers
M
M
Ludlow
H
H
Lourenco
P
P
Ghazal
P
P
Williams
A R
AR
Critchley
H O D
HO
Duncan
W C
WC
D000022:Abortion, Spontaneous / Q000235:genetics / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D002478:Cells, Cultured; D003656:Decidua / Q000378:metabolism; D015536:Down-Regulation; D010064:Embryo Implantation / Q000235:genetics / Q000502:physiology*; D004717:Endometrium / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D028322:Inhibin-beta Subunits / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D011247:Pregnancy; D011274:Pregnancy, Tubal / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution
C422402:INHBB protein, human; D021122:Protein Subunits; D028322:Inhibin-beta Subunits