Expression Of ISG15 And PIBF In Ovine Bone Marrow During Early Pregnancy

The immune organ is composed of central immune organs and peripheral immune organ, and the central immune organ contains bone marrow and thymus. Bone marrow is the birthplace of T lymphocytes, and an important function of bone marrow is to generate stem cells of various types. These stem cells differentiate and then generate a variety of blood cells, such as red blood cells, white blood cells, platelets, etc, Therefore, the bone marrow is not only the hematopoietic organs, and also very important in the maintenance of the body’s life andimmunity. In order to explore the effects of early pregnancy on central immune organs(bone marrow) in sheep, the ewes with normal reproductive function were selected to study the effects of early pregnancy on expression of ISG15 and PIBF by bone marrow. The progesterone suppository sponge were used to synchronizate estrus, and mated for ewes in heat(control group without mating). The bone marrows from day 16 of non-pregnancy, days 13, 16 and 25 of pregnancy were sampled after estrus(through observing the existence of conceptus after the slaughter and anatomy, confirming the ewes with days 13, 16 and 25 of pregnancy). The samples of bone marrow from different days of pregnancy or non-pregnancy were placed in 2mL cryovial in liquid nitrogen of-196℃, and shipped to the laboratory for detection of mRNA expression and Western blot analysis. Otherwise, the samples of ovine bone marrow from different days of pregnancy or non-pregnancy were washed with PBS solution and fixed in 4% paraformaldehyde solution, and then were used for immunohistochemical detection. The results were as the follows:1. The results of real-time quantitative PCR detection and Western blot analysis showed that the expression levels of ISG15 mRNA and protein in the ovine bone marrow were increased gradually during the period of early pregnancy, and the expression level of ISG15 mRNA and protein in ovine bone marrow from day 16 of pregnancy was higher than that in the day 16 of non-pregnancy, days 13 and 25 pregnancy, and the expression level of ISG15 mRNA and protein reached the peak in the day 16 of pregnant bone marrow. However, the expression level of ISG15 mRNA and protein from day 25 of pregnant bone marrow was decreased gradually. The staining intensity of ISG15 protein in the ovine bone marrow from day 16 of pregnant bone marrow was stronger than that in day 16 of non-pregnant, days 13 and 25 pregnant bone marrow, and ISG15 protein mainly was in the cytoplasm of interstitial cells of bone marrow. In conclusion, Interferon-tau derived from conceptus up-regulated the expression of ISG15 mRNA and protein in the bone marrow during early pregnancy in sheep.2. The expression level of PIBF mRNA and protein detection that in day 16 pregnant bone marrow was higher than that in day 16 of non-pregnancy, days 13 and 25 of pregnancy in sheep, and reached the highest in the day 16 of pregnant bone marrow. The expression level of PIBF mRNA from day 25 of pregnancy decreased gradually. The expression pattern of the PIBF protein was almost consistent with that of mRNA expression. PIBF protein was expressed in bone marrow from days 13, 16 and 25 of pregnancy, but there was no expression of the PIBF protein in bone marrow from day 16 of non-pregnancy. The expression level of the PIBF protein was higher in bone marrow from days 16 and 25 of pregnancy than that from day 13 of pregnancy. The expression of PIBF protein was significantly expressed in the bone marrow from days 16 and 25 of pregnancy, and there was no difference in expression of the PIBF protein from days 16 and 25 of pregnancy.In conclusion, Interferon-tau derived from conceptus up-regulated the expression of ISG15 mRNA and protein in the bone marrow through blood circulation during early pregnancy in sheep, which also inhibited the degradation of the corpus luteum. The corpus luteum continued to produce progesterone, which induced the up-regulation expression of PIBF protein, and regulated the immune function of the bone marrow. The ovine embryo was not rejected by maternal immune system, which was in favor of the pregnancy maintenance.