Deciphering the embryo-maternal interactome: Embryo-dependent programming of endometrial function during early pregnancy in cattle

• Ano de defesa: 2019
• Autor(a) principal: Sponchiado, Mariana
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Blastocisto; Blastocyst; Embryo-maternal signaling; Morula; Mórulas; Sinalização materno-embrionária; Útero; Uterus
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/10/10131/tde-25112019-160346/

A successful pregnancy is dependent on the intrinsic embryonic program, operating in conjunction with extrinsic signals emanating from the maternal reproductive tract, as well as on a coordinated interaction between the embryonic and the maternal units. Current knowledge about the pre-elongation embryo-dependent programming of endometrial function in cattle is limited. Central hypothesis is that bovine embryos are able to modulate the endometrial function as early as day 7 after estrus. In the first study, spatially defined regions of the endometrium transcriptome were interrogated for responses to a day 7 embryo in vivo. Endometrial samples were collected from the uterotubal junction, anterior, medial and posterior regions of the uterine horn ipsilateral to the corpus luteum 7 days after estrus from sham-inseminated or artificially inseminated, confirmed pregnant Nellore cows. Abundance of 12 out of 87 transcripts analyzed was modulated in the pregnant endometrium, including classic interferon-induced genes and transcripts associated to eicosanoid biosynthesis. Changes were predominantly in the most cranial portion of the uterine horn, where the embryos were located. In addition, abundance of 71 transcripts varied according to region of the reproductive tract, irrespective to the pregnancy status. Targeted mass spectrometry-based quantification of 205 metabolites in the uterine luminal fluid (ULF) recovered from the most cranial portion of the ipsilateral uterine horn showed that exposure to a day-7 embryo changes ULF composition in vivo. Embryo-induced modulation included an increase in concentrations of lipoxygenase-derived metabolites and a decrease in concentrations of amino acids, biogenic amines, acylcarnitines and phospholipids. The changed composition of the ULF could be due to secretion or depletion of specific molecules, executed by either the embryo or the endometrium, but initiated by signals coming from the embryo. In the second study, an in vitro model was used to probe embryo-induced changes on bovine endometrial epithelial cells (BEECs) transcriptome and investigate modes of inter-tissues molecular communication. In vitro-produced morulae were co-cultured in juxtaposition or without a direct contact with a BEEC monolayer. Extra groups of BEECs or embryos alone were cultured as controls. Irrespective of juxtaposition to the cell monolayer, co-culture with BEECs improved blastocyst rates on day 7.5. Physical proximity between embryos and the BEEC monolayer, nevertheless, did alter nature and intensity of embryo-induced changes on BEEC transcriptome. Embryos juxtapositioned modulated transcription of 1,797 versus 230 genes in BEECs not contacting embryos directly, in relation to cells cultured in the absence of embryos. Pathways modulated by presence of embryos included interferon-mediated immune responses, cell cycle regulation and apoptosis, prolactin signaling, and prostanoid biosynthesis. Overall, from the results obtained in the course of this thesis, we conclude that peri-hatching bovine embryos modulate the endometrial function. Herein, we provide candidate systems that might be important for conditioning the uterine environment for conceptus development. Early embryonic signaling might be necessary to guarantee optimal development and successful establishment of pregnancy in cattle.