Metritis is associated with reduced fertility in dairy cows, but the mechanisms are unclear because the disease resolves several weeks before insemination. One hypothesis is that metritis causes persistent changes in granulosa cells during follicle development, which might be evident in the transcriptome of granulosa cells from dominant follicles weeks after parturition. To test this hypothesis, we collected the follicular fluid and granulosa cells from dominant follicles 63 days post partum from cows previously diagnosed with metritis, at least 6 weeks after resolution of the disease and from cows not diagnosed with metritis (control cows). Bacterial lipopolysaccharide was detected in follicular fluid, and concentrations were associated with follicular fluid IL-8 and glucose concentrations. Transcriptome analysis using RNAseq revealed 177 differentially expressed genes in granulosa cells collected from cows that had metritis compared with control cows. The most upregulated genes were ITLN1, NCF2, CLRN3, FSIP2 and ANKRD17, and the most downregulated genes were ACSM1, NR4A2, GHITM, CBARP and NR1I3. Pathway analysis indicated that the differentially expressed genes were involved with immune function, cell–cell communication, cell cycle and cellular metabolism. Predicted upstream regulators of the differentially expressed genes included NFκB, IL-21 and lipopolysaccharide, which are associated with infection and immunity. Our data provide evidence for a persistent effect of metritis on the transcriptome of granulosa cells in ovarian follicles after the resolution of disease.
Rachel L Piersanti, Anthony D Horlock, Jeremy Block, José E P Santos, I Martin Sheldon and John J Bromfield
Jason A Rizo, Laila A Ibrahim, Paula C C Molinari, Bo R Harstine, Rachel L Piersanti and John J Bromfield
Semen induces post-coital inflammation of the endometrium in several species. Post-coital inflammation is proposed to alter the endometrial environment of early pregnancy, mediate embryonic development and modulate the maternal immune response to pregnancy. In cattle, it is common for pregnancies to occur in the absence of whole semen due to the high utilization of artificial insemination. Here, we have utilized a cell culture system to characterize semen-induced expression of inflammatory mediators in bovine endometrial cells and test the efficacy of transforming growth factor beta as the active agent in mediating any such change. We hypothesize that seminal plasma-derived transforming growth factor beta increases the expression of inflammatory mediators in bovine endometrial cells. Initially, we describe a heat-labile cytotoxic effect of seminal plasma on BEND cells, and a moderate increase in IL1B and IL6 expression. In addition, we show that transforming growth factor beta is present in bovine semen and can increase the expression of endometrial IL6, whereas blocking transforming growth factor beta in semen ameliorates this effect. However, intra-uterine infusion of seminal plasma, sperm or transforming growth factor beta did not alter the endometrial expression of inflammatory mediators. We conclude that bovine semen can modulate endometrial gene expression in vitro, which is partially due to the presence of transforming growth factor beta. It is likely that additional, unidentified, bioactive molecules in semen can alter the endometrial environment. Characterizing bioactive molecules in bovine semen may lead to the development of additives to improve artificial insemination in domestic species.