Response of bovine luminal endometrial epithelial cells to stimulus provided by bovine trophoblast cells and conjugated linoleic acid in a co-culture system

Abstract

Early embryonic mortality, caused by failures in maternal-fetal recognition in the first three weeks after fertilization represents a major cause of reproductive inefficiency in the cattle industry. During this pre-implantation period, the conceptus (embryo and its associated extra-embryonic membranes) present in the uterine lumen must secrete molecules, such as interferon-tau (IFNT), that interact with the endometrium to inhibit prostaglandin F2± synthesis and luteolysis, a determining condition for the establishment of pregnancy. Mechanisms regulated by conceptus IFNT in bovine uterine epithelial cells (BUECs) include the upregulation of transcription of IFN-stimulated genes (ISGs). A major gap in the current knowledge on the field of pre-implantation biology in cattle is the nature of one-to-one endometrium and embryo interactions that result in positive or negative pregnancy outcomes. Understanding such interactions will serve as basis to develop strategies that can benefit the maternal-embryo recognition, which are of scientific and economic interest. However, models to study the embryo-endometrium interactions in vitro are limited. The main objective is to develop and validate an in vitro co-culture model to determine the response of BUECs to a bovine trophoblast cell line (CT-1) and to exogenous stimuli, such as conjugated linoleic acid (CLA). Here, we propose to characterize the transcription of ISGs, such as ISG15, OAS1, and MX2 in BUECs, after co-culture with CT-1 and exposure to CLA. The hypothesis is that BUECs derived from different cows respond differently to the stimuli provided by CT-1 and CLA. Contrasting responses among different cows is expected to be associated with different individual-cow endometrial receptivity to implantation as well as survival, growth, and development of the conceptus. (AU)