Effects of interferon-τ and interferon-α on proliferation of bovine endometrial cells

The ruminant conceptus secretes a unique interferon, interferon-τ, that regulates endometrial prostaglandin secretion during early pregnancy. Because one of the pleiotropic effects of interferons is to inhibit cellular proliferation, a series of experiments was conducted to determine whether or not the bovine endometrium is sensitive to the antiproliferative effect of interferon-τ and the related interferon, interferon-α. Endometrial epithelial and stromal cells were prepared from the endometrium of cows from Days 11-17 after estrus and incubated with recombinant bovine interferon-τ (rbIFNτ; 1-1000 ng/ml), recombinant bovine interferon-α1 (rbIFNα; 1-1000 ng/ml), recombinant human interferon-α2b (rhIFNα; 100 ng/ml), or ovine interferon-τ (oIFNτ; 100 ng/ml). Proliferation was determined by monitoring uptake of [³H]thymidine into DNA. Generally, interferons did not inhibit proliferation of endometrial epithelial cells. Exceptions were for 1000 ng/ml rbIFNτ, which inhibited proliferation by 23%; 100 ng/ml rbIFNα, which inhibited proliferation by 28% in one of two experiments only; and 100 ng/ml oIFNτ, which inhibited proliferation by 17%. Proliferation of endometrial stromal cells was not inhibited by any concentration of any interferon in two separate experiments. Therefore, unlike other bovine cells tested previously (lymphocytes and oviductal cells), bovine endometrial cells were not consistently inhibited by IFNτ or IFNα. Such reduced responsiveness of endometrial cells to the antiproliferative effects of type 1 interferons could allow for growth of the endometrium during the period of pregnancy when the conceptus produces IFNτ.