Context: The human endometrium acquires the ability to allow embryo attachment just for a specific period of time during each menstrual cycle. Understanding of the opposite functional status, referred to as refractoriness, can potentially be used to improve receptivity in infertile patients or as an interceptive approach to prevent gestation.
Objective: The objective of the study was to analyze the endometrial gene expression profile induced by an inert intrauterine device (IUD) at the time of implantation.
Design: We used a microarray containing more than 16,000 cDNAs to investigate the gene expression profile of receptive vs. refractory endometrium in the same women induced by the presence of an IUD. We compared the gene expression profile of endometrium obtained at LH+7 (window of receptivity) from the same women (n = 5) at the following time points: month 1, corresponding to the natural cycle before IUD insertion; month 3, just before IUD removal; and months 5 and 15. Data were validated by quantitative RT-PCR for IGF binding protein-3, peroxisome proliferative activated receptor-gamma, glycodelin, and leukemia inhibitory factor and immunohistochemistry for glycodelin.
Results: We identified 147 genes significantly dysregulated in the refractory endometrium (78 up- and 69 down-regulated). Interestingly, 52 of these genes have previously been reported to be regulated during window of implantation. Surprisingly, the majority of genes (96.6%) remained dysregulated 2 months after IUD removal, but 1 yr later most of them (80%) returned to normal.
Conclusions: Our results reveal that a refractory endometrium in a fertile woman produced by an IUD is induced by preventing the normal transition to a receptive gene expression profile through effects on a specific subset or cluster of genes that impact on endometrial receptivity.