(244) Dynamic Expression of Interferon-Stimulated Genes and Pregnancy-Associated Glycoproteins in Beef Cows Supplemented with Progesterone During Early Pregnancy

Lillian X. Ehresmann¹; Florentino P.J. da Silva Junior¹; Ellie G. Kidwell¹; Paulo M. Bonacim¹; Calista G. Hubbard¹; Ava C. Gaines¹; Rafael R. Domingues¹

1. Department of Animal Sciences, The Ohio State University, Columbus, OH USA

Abstract Text:

Progesterone (P4) is essential for pregnancy establishment and maintenance in cattle. Supplementation of P4 during the pre-implantation period has been shown to enhance embryonic growth; however, the impact on embryonic secretion of interferon tau and pregnancy-associated glycoprotein (PAG) along with maternal response to these signals remain ill-defined. We aimed to evaluate the effect of P4 supplementation on uterine endometrial and cervical cells expression of interferon-stimulated genes and PAG during the peri-implantation period in Bos taurus beef cattle. In experiment 1, cows underwent estrus synchronization, artificial insemination (d0), and were randomly assigned to receive an intravaginal P4 device (CIDR, 1.38g of P4) from d3 to d12 (sP4; n=14) or remain untreated (control; n=13). Blood samples were collected until day 24. Uterine cervical cells were collected on d3 (baseline) and every other day from d12 to d24 for assessing mRNA abundance of interferon-stimulated gene 15 (ISG15). Only pregnant cows on d24, based on ultrasonography and circulating PAG, were used for all analyses. In experiment 2, cows were similarly synchronized, inseminated and assigned into sP4 (n=13) or control (n=17) groups. Uterine endometrial cells were collected on d18. Endometrial abundance of ISG15 and myxovirus resistance 2 (MX2) were determined on d18 (nonpregnant, n=8; pregnant, n=22) and on d24 (collected during experiment 1; pregnant, n=16). Data were analyzed using generalized mixed models. In experiment 1, the sP4 group had greater (P< 0.05) circulating P4 concentrations from d4 to d12 then remained similar between groups until d24. First day of PAG detection in maternal circulation tended (P=0.06) to be earlier in the sP4 group (d19.1±0.4) compared to the control (d20.0±0.3). Overall, PAG concentrations were greater on d19 (0.4±0.1 vs 0.2±0.0 ng/mL; P=0.02) and tended to be greater on d20 (1.1±0.2 vs 0.6±0.2 ng/mL; P=0.08) in the sP4 group. In pregnant cows, mRNA abundance of cervical ISG15 was not different (P=0.85) between control and sP4 groups. There was only a significant effect (P< 0.0001) of time on the profile of cervical ISG15 mRNA abundance. Compared to d3 baseline, expression of ISG15 was greater (P< 0.0001) on d12 (3.0-fold) followed by increasing abundance on d14 (98.8-fold) and d16 (73.7-fold), a plateau from d16 to d20, and later decrease on d24 (16.7-fold). In experiment 2, there was a significant effect of pregnancy status (d18 nonpregnant vs d18 and d24 pregnant) on endometrial ISG15 and MX2 expression; however, there was no effect of sP4 on endometrial gene expression (P >0.3). Compared to the baseline (d18 nonpregnant), ISG15 mRNA abundance was greater (P< 0.0001) on d18 and d24 (171.5-fold and 100.4-fold, respectively). For MX2, mRNA abundance was greater (P< 0.0001) on d18 and d24 (138.4-fold and 50.1-fold, respectively) compared to the baseline, but decreased (P< 0.01) between d18 and d24. Considered together, these findings suggest that P4 supplementation from d3 to d12 does not affect embryonic secretion of interferon tau, at least as indicated by indirect assessment of endometrial and cervical expression of ISG15 and MX2. Nevertheless, P4 supplementation resulted in earlier PAG detection in maternal circulation likely due to hastened embryonic growth and differentiation of trophoblast cells into PAG-producing phenotypes. Importantly, we demonstrated that collection of uterine cervical cells may be performed multiple times without compromising pregnancy, allowing for profiling of maternal response to embryonic interferon tau as a method for assessing embryonic viability and pregnancy status during early pregnancy.