The endometrial response to pregnancy is altered in cows after uterine infection.

Pregnancy induces changes in the transcriptome of the bovine endometrium from 15 days after insemination. However, pregnancy is less likely to occur if cows had a postpartum bacterial infection of the uterus. We hypothesized that uterine bacterial infection alters the endometrial transcriptomic signature of pregnancy. To examine the endometrial transcriptomic signature of pregnancy, cows were inseminated 130 days after intrauterine infusion of pathogenic bacteria and endometrium was collected 16 days later for RNA sequencing. We found 171 pregnancy regulated genes in cows 146 days after bacterial infection. When comparing our findings with three previous studies that described the endometrial transcriptomic signature of pregnancy in healthy cows, 24 genes were consistently differentially expressed in pregnancy, including MX1, MX2 and STAT1. However, 12 pregnancy regulated genes were only found in the endometrium of healthy cows, including ISG15 and TRANK1. Furthermore, 28 pregnancy regulated genes were only found in the endometrium of cows following bacterial infection and these were associated with altered iNOS, TLR, and IL-7 canonical signaling pathways. Although 94 predicted upstream regulators were conserved amongst the studies, 14 were found only in the endometrium of pregnant healthy cows, and 5 were found only in cows following bacterial infection, including AIRE, NFKBIA, and DUSP1. In conclusion, there were both consistent and discordant features of the endometrial transcriptomic signature of pregnancy 146 days after intrauterine bacterial infusion. These findings imply that there is an essential transcriptomic signature of pregnancy, but that infection induces long term changes in the endometrium that affect the transcriptomic response to pregnancy. Overall design: To understand effect of uterine infection on endometrium, seven cows received intrauterine infusion of pathogenic E. coli and T. pyogenes to mimic a uterine infection. Cows were inseminated 130 days after bacteria infusion, and uteri collected and classified as pregnant or non-pregnant at day 16 post-insemination (146 days after bacteria infusion). To analyze the impact of bacteria infusion on the endometrial transcriptomic signature of pregnancy, intercarunular endometrium was collected and processed for RNA sequencing. We hypothesized that uterine bacterial infection alters the endometrial transcriptomic signature of pregnancy.