Poster Presentation Annual Meetings of the Endocrine Society of Australia and Society for Reproductive Biology and Australia and New Zealand Bone and Mineral Society 2016

Insights into endometrial-embryo interaction: modulating the endometrial epithelial proteome, secretome, and defining the role of exosomes during implantation (#480)

David Greening 1 , Hong Nguyen 2 , Jemma Evans 2 , Richard Simpson 1 , Lois Salamonsen 2
  1. La Trobe Institute for Molecular Science, Melbourne, Australia, VIC, Australia
  2. Centre for Reproductive Health, Hudson Institute of Medical Research, Melbourne, VIC, Australia

Communication between a developing embryo and hormonally-primed endometrium is essential to achieve implantation and establish pregnancy. Importantly, the point-of-first-contact between the embryo and the maternal-endometrium occurs at the endometrial luminal epithelium. We highlight for the first time a unique insight into the developmental biology of embryo implantation – investigating cellular and secreted changes important for receptivity and implantation, and the contribution of exosomes in regulating this microenvironment. Utilising a combination of cell models, targeted physiologically relevant treatments, and quantitative proteomics, we demonstrate endometrial epithelial cellular and secreted protein changes in response to ovarian steroid hormones that drive development of the endometrium to become ‘receptive’ to an embryo, and to the blastocyst-derived hormone, human chorionic gonadotrophin, which enhances endometrial changes essential for receptivity and implantation. We identified cellular changes associated with metabolism, basement membrane and cell connectivity, proliferation and differentiation, while the secretome analysis identified proteins differentially regulated in associated with cellular adhesion, extracellular-matrix organization, developmental growth, growth factor regulation, and cell signalling. Further, we demonstrate that exosomes (40-150nm nanovesicles) released from endometrial epithelial cells are an important component of these interactions during receptivity and implantation. Utilizing quantitative proteomics we defined the proteome of purified endometrial epithelial-derived exosomes influenced by menstrual cycle hormones estrogen and progesterone, revealing significant reprogramming associated with cell adhesion, migration, invasion, and extracellular matrix remodeling. In addition to hormonally-treated endometrial cell/secreted and exosomal proteins changes, all findings were validated in human primary uterine epithelial cell-derived material (cells/secretome/exosomes). Functionally, exosomes were internalized by human trophoblast cells and enhanced their adhesive capacity; a response mediated partially through active focal adhesion kinase signaling. Together, our results illustrate the dynamic intracellular and secreted protein changes in the endometrium and responses to the pre-implantation embryo, and an active contribution of exosomes to regulating this environment, that together ensure successful establishment of pregnancy.