Endometrial laminin subunit beta-3 expression associates with reproductive outcome in patients with repeated...

Endometrial laminin subunit beta-3 (LAMB3) is a candidate gene whose expression distinguishes the endometrial window of receptivity (WOR) in human. This study aims to examine endometrial LAMB3 levels in patients with repeated implantation failure (RIF), in order to assess the ability of LAMB3 to predict pregnancy outcome.

Endometrial biopsies were taken during the WOR from 21 healthy volunteers in natural menstrual cycles and from 50 RIF patients in mock cycles prior to frozen embryo transfer (FET) cycles. Immunohistochemistry (IHC) staining of LAMB3 was performed, and the H-score was correlated with the pregnancy outcome in subsequent FETs.

In healthy volunteers, endometrial LAMB3 was demonstrated to be highly expressed during the WOR with the staining exclusively in the cytoplasm of the epithelial cells. In a discovery set of RIF patients, the LAMB3 expression level was found to be significantly higher in those who conceived compared to those who did not in subsequent FETs. A receiving operator characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.7818 (95% confidence interval 59.92-96.44%) with an H-score cutoff of 4.129 to differentiate cases with positive or negative pregnancy outcomes. This cutoff achieved an accuracy of 75% in pregnancy prediction in a following validation set of RIF patients, in which the pregnancy rate in subsequent FETs was three-fold higher when the mock cycle LAMB3 H-score was ≥ 4.129 compared to < 4.129.

IHC measurement of endometrial LAMB3 expression could be a promising prognostic method to predict pregnancy outcome for RIF patients undergoing FETs.