There is an immune tolerance in maternal immune system during pregnancy, and thymus is a main organ of the immune system. Helper T (Th)1 and Th2 cytokines are involved in the regulation of immune system, but the modulation of Th cytokines in the thymus during early pregnancy is unclear in ewes. Thymuses were collected on day 16 of the estrous cycle, and on days 13, 16, and 25 of pregnancy in ewes. qRT-PCR, Western blot, and immunohistochemistry were used to analyze the expression of Th1 and Th2 cytokines in the thymuses. There was a peak in the expression of interferon-gamma (IFN-γ) on day 16 of pregnancy, an upregulation of tumor necrosis factor beta (TNF-β), and a sustained expression of interleukin-2 (IL-2) and IL-4. Furthermore, there was a peak in the expression of IL-6 on day 13 of pregnancy, no expression of IL-6 on day 16 of the estrous cycle and day 25 of pregnancy, and an upregulation of IL-5 and IL-10 in the thymuses during early pregnancy. The immunohistochemistry results revealed that the IFN-γ and IL-6 proteins were limited to the stromal cells, capillaries, and thymic corpuscles. In conclusion, early pregnancy influenced the production of Th1 and Th2 cytokines of maternal thymus in sheep.
The spleen combines the innate and adaptive immune systems, and the early conceptus must regulate the maternal intrauterine immune and systemic immune response during early pregnancy in sheep. However, it is unclear whether early pregnancy exerts its effects on the characterization of the T helper (Th) cytokines profile in the spleen during early pregnancy in ewes. In this study, spleens were obtained at day 16 of the oestrous cycle and at days 13, 16 and 25 of pregnancy (n = 6 for each group) from ewes, and qRT-PCR, western blot and immunohistochemistry analysis were used to analyze the Th cytokines profile of the spleens. Our results showed that there was down-regulation of IFN-γ at days 13 and 16 of pregnancy, but there was upregulation of IL-2, IL-5 and IL-6 at day 25 of pregnancy, TNF-β at days 16 and 25 of pregnancy, and IL-4 and IL-10 in all pregnant groups. Immunohistochemistry results showed that the IL-6 protein was limited to the capsule, trabeculae and splenic cords. This paper reported, for the first time, that characterization of the Th cytokines profile varied in the maternal spleen during early pregnancy, which may be essential for successful pregnancy in sheep.
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