Galectin-7 acts as an adhesion molecule during implantation and increased expression is associated with miscarriage

Introduction: Galectins are expressed at the fetal-maternal interface and have multiple roles including during blastocyst implantation. The expression of galectin-7 however has not been investigated in the uterus. We aimed to localise galectin-7 to the endometrium of women with normal fertility and with a history of miscarriage and prospectively determine whether serum levels are altered in women who subsequently miscarry. We also investigated the role of galectin-7 on trophoblast-endometrial epithelial cell adhesion.

Methods: Immunohistochemistry localised galectin-7 to endometrium throughout the menstrual cycle in women (normal fertility or with history of miscarriage) and in first trimester implantation sites. Galectin-7 serum levels were determined by ELISA. We used both endometrial epithelial-trophoblast cell lines and primary cells for cell-cell adhesion experiments.

Results: Galectin-7 immunolocalized to endometrial luminal and glandular epithelium in normally fertile women and was upregulated in epithelium and stroma of women with a history of miscarriage. Similarly, galectin-7 serum levels were elevated at 6 weeks gestation in women who subsequently miscarried compared to gestation matched controls. Exogenous galectin-7 reduced endometrial epithelial-trophoblast adhesion in cell-line and primary cell assays. However, when endometrial epithelial cells were isolated from women with endometrial disorders, galectin-7 increased epithelial-trophoblast adhesion.

Conclusions: Galectin-7 is produced by endometrial epithelium and is abnormally elevated in the endometrium of women with a history of miscarriage. Serum levels may be useful as a predictive biomarker of miscarriage. Our data suggests that galectin-7 facilitates adhesion of the embryo to the endometrium and elevated galectin-7 may result in abnormal adhesion.