Intrauterine Infusion of TGF-β1 Prior to Insemination, Alike Seminal Plasma, Influences Endometrial Cytokine Responses but Does Not Impact the Timing of the Progression of Pre-Implantation Pig Embryo Development

SIMPLE SUMMARY: Although endometrial immune regulation in pigs during the early preimplantation period is poorly documented, particularly under conditions of embryo transfer (ET), it is recognized that seminal plasma (SP) induces molecular changes in the reproductive tract, influencing numerous reproductive functions. A principal constituent of SP is the cytokine transforming growth factor β1 (TGF-β1), which has an important role in embryo development, pregnancy establishment, and progression. The present study evaluated different intrauterine infusion treatments at estrus (40 mL of SP, porcine TGF-β1 in an extender, or an extender alone (control)) by mimicking an ET scenario in so-called “donor” (inseminated) and “recipient” (uninseminated) sows. We investigated the effects of these treatments on day 6 embryo development (“donors”) and endometrial explants’ cytokine production (“donors” and “recipients”). SP infusion positively influenced embryo development compared with TGF-β1 or extender infusions. Infusion treatments differentially affected endometrial cytokine production, with the effects being stronger in “donors” than in “recipients.” Increased knowledge of the effects of SP or some of its active components on the female immune system may help to develop strategies for increasing the reproductive efficiency for the benefit of pig ET. ABSTRACT: Seminal plasma (SP) in the female genital tract induces changes that affect multiple reproductive processes. One of the active components in SP is the transforming growth factor β1 (TGF-β1), which has major roles in embryo development and pregnancy. Embryo transfer (ET) technology is welcomed by the pig industry provided that embryo quality at embryo collection as well as the fertility and prolificacy of the recipients after the ET is increased. This study evaluated different intrauterine infusion treatments at estrus (40 mL of SP, TGF-β1 cytokine in the extender, or the extender alone (control)) by mimicking an ET scenario in so-called “donor” (inseminated) and “recipient” (uninseminated) sows. On day 6 (day 0—onset of estrus), all “donors” were laparotomized to determine their pregnancy status (presence and developmental stage of the embryos). In addition, endometrial explants were collected from pregnant “donors” and cyclic “recipients,” incubated for 24 h, and analyzed for cytokine production. SP infusions (unlike TGF-β1 infusions) positively influenced the developmental stage of day 6 embryos. Infusion treatments differentially influenced the endometrial cytokine production, mainly in donors. We concluded that SP infusions prior to AI not only impacted the porcine preimplantation embryo development but also influenced the endometrial cytokine production six days after treatment, both in donors and recipients.