PSIV-13 - Changes in Interferon-γ and Tumor necrosis factor-α in the vaginal environment of cattle during early gestation

Abstract: The embryo must create an immuno-tolerant uterine environment via cytokine signaling to prevent rejection and facilitate embryo attachment. Cytokines play a variety of roles in both reproductive and pregnancy-related processes. Cytokines and chemokines are important in inflammatory pathways for uterine remodeling and recruitment of immune cells during pregnancy. Interferon-γ (INFγ) and Tumor necrosis factor-a (TNFα) influence T-helper cell immune responses, which can assist in early pregnancy establishment. Therefore, we hypothesized that INFγ and TNFα concentrations following breeding will be differentially expressed based on mating type, time, and pregnancy outcome. To test this, we completed two experiments in which INFγ and TNFα were quantified in vaginal fluid samples on d0, d7, d14, d21, d28, and d35 following mating. In experiment one, Angus heifers (n=9) were utilized to determine cytokine concentrations in the vaginal environment between d0 to d35, and between artificial insemination (AI) and natural mating. In experiment two, lactating dairy cows (n=88) were utilized to determine if cytokines could be used as a potential biomarker for successful pregnancy. All vaginal flush samples were collected via Foley catheter in 20 mL of sterile saline. Statistical analysis was completed in SAS 9.4 to determine differences in cytokine concentrations based on day of gestation, mating type, and pregnancy outcome. In experiment 1, vaginal concentrations of TNFα were lowest (P = 0.05) in AI-bred heifers on d35 (1.15 ± 2.97 pg/mL) and intermediate in non-pregnant heifers (4.39 ± 2.97 pg/mL) compared with natural service-bred heifers on d7 (18.09 ± 2.97 pg/mL). INFγ was increased (P = 0.05) on d7 following natural service (3.86 ± 0.76 pg/mL) compared with AI (0.86 ± 0.76 pg/mL). TNFα was increased (P = 0.02) on d7 following natural service (18.09 ± 2.89 pg/mL) compared with AI (1.93 ± 2.89 pg/mL) and was found to be increased (P = 0.02) by d7 after a natural mating compared with a pregnancy resulting from AI mating. In experiment two, concentrations of IFNγ were greater (P = 0.04) on d7 (1.36 ± 0.57 pg/mL) compared with d8 (0.24 ± 0.57 pg/mL) of gestation. There was also a tendency for TNFα concentrations to decrease (P = 0.09) from d7 (60.06 ± 26.94 pg/mL) to d8 (19.67 ± 26.94 pg/mL) of gestation. In conclusion, concentrations of INFγ and TNFα may not be indicative of a viable embryo or pregnancy outcome but do differ based on day of gestation and mating type, which may aid in understanding the role these cytokines play during early gestation.