Abstract

Simple Summary Cytokines and prostaglandins are inflammatory mediators that are secreted by the immune cells but also by the female genital tract to regulate immune maternal tolerance. The balance of an adequate uterine immune response promotes reproductive success. No information is available regarding the characterization of inflammatory mediators in the uterine fluid of llamas during different stages of the reproductive cycle. Therefore, the main goal of the study was to determine the presence of these inflammatory mediators in the uterine fluid of llamas in the follicular and luteal phase induced using different stimuli of ovulation induction, among them, the intrauterine infusion of llama seminal plasma. Although there were inflammatory mediators present in both phases of the reproductive cycle, llamas in the luteal phase induced by seminal plasma presented the highest concentration of inflammatory mediators indicating that seminal plasma is rich in compounds that significantly influence the endometrial secretion of these inflammatory mediators. The establishment of a state of immunotolerance in the female reproductive tract is important for embryo development, implantation and placentation. Llamas are induced ovulators and more than 98% of pregnancies occur in the left uterine horn. The objective of this study was to determine the uterine immune response of llamas in different stages of the reproductive cycle. Adult llamas (n = 20) were examined daily by transrectal ultrasonography to determine follicular growth and then randomly assigned to four groups: Follicular phase (n = 5); Luteal phase induced by an intramuscular administration of 50 ug of GnRH analogue (n = 5); Luteal phase induced by intrauterine infusion of seminal plasma (n = 5); and Luteal phase induced by mating (n = 5). Uterine fluid was collected separately from both uterine horns by non-surgical flushing to determine the presence of cells, total proteins and concentration of IL-1 beta, IL-6, IL-8, IFN gamma, TNF-alpha and PGE2. Inflammatory cells were not observed in the uterine fluid and total protein pattern and inflammatory mediators did not differ between the left and the right horn amongst groups. Llamas treated with an intrauterine infusion of seminal plasma showed the highest concentration of total proteins, inflammatory cytokines PGE2, IL-8 and IL-1 beta in the uterine fluid. In conclusion, seminal plasma is made up of significant numbers of signaling molecules that are able to modify the uterine immune response in llamas.