Lymphocyte Soluble Factors from Pregnant Cows Modulate mRNA Transcript Abundances Encoding for Proteins Associated with Trophoblast Growth and Development

This study was conducted to determine whether T cell populations are responsible for modulating placental development during gestation in cattle. It was hypothesized that CD4+CD25+ and γ/δ+ T cells modulate gene expression, based on mRNA transcript abundances, and promote proliferation and survival of trophoblast cells. Peripheral blood was collected from cows at 160 to 180 days of gestation and non-pregnant cows, T cell populations CD8+, CD4+, CD4+CD25+, CD24+CD25-, and γ/δ+ T cells were isolated, cultured for 48 h, and supernatant was collected. Placental samples were digested, and trophoblast cells were cultured for 24 h. Trophoblast cells were cultured with 50 μL of T cell-conditioned media and 50 μL of fresh culture media for an additional 48 h. Samples in control wells were treated with unconditioned media. Trophoblast cell proliferation, apoptosis, and mRNA transcript assays were conducted. There was no effect of T cell population on trophoblast apoptosis rate, proliferation, and relative mRNA transcript abundances. The T cell supernatant from pregnant and non-pregnant cows induced greater apoptosis rates in trophoblast cells than unconditioned media. Trophoblast cells proliferated less when treated with T cell supernatant from pregnant compared to unconditioned medium and non-pregnant cows. Treatment with the T cell supernatant from pregnant cows resulted in larger abundances of BMP5, IGF1R, PAG10, FGF2, RSPO3 and TMED2 and also a lesser abundance of FGF2 mRNA transcript than non-pregnant group and unconditioned media treatments. Supernatant from T cell derived from pregnant cows modulates trophoblast mRNA transcript abundances differently from T cell supernatant of non-pregnant cows

Identification of Bovine T-Cell Populations Involved in Placental Growth and Development

Today, the dairy industry is comprised of cows that can produce around 20,000 pounds of milk in a year, yet producers often see only 30% to 50% of animals produce a live calf after each breeding. While many factors may be at play, there is evidence that the immune system plays a large role in regulating pregnancy and in preventing immune mediated abortions. Maternal immune system changes during pregnancy have been shown to occur both locally in the uterus, which is in direct contact with the placenta, and systemically in the blood. Research in humans and mice has shown that the immune cell populations of CD4+CD25+ γ/δ TCR+ play substantial roles as T regulatory cells and they support the development of the conceptus through trophoblast cell growth. However, in cattle these cells have not been identified. We proposed a co-culture experiment to identify which T cell populations in the cow support placental growth. We isolated and cultured the following T cell populations: CD4+, CD4+CD25+, CD4+CD25-, CD8+, and γ/δ TCR+ from pregnant and non-pregnant cows to obtain T cell conditioned medium and treat placental trophoblast cells. T cells secrete cytokines and growth factors that might alter trophoblast cell growth and development. We analyzed trophoblast cell proliferation, apoptosis, and gene expression to identify which T cell populations support placental development. Our results show that trophoblast cell gene expression is modulated by T cell supernatant obtained from pregnant cows differently than T cell supernatant from non-pregnant cows. These results will contribute to the development of strategies that could reduce rates of immune-mediated pregnancy loss. A cost-effective approach to reduce pregnancy loss in cattle could reduce monetary loss to farmers by allowing production animals to be more reproductively efficient and stay in the herd for longer