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Possible role of IFNT on the bovine corpus luteum and neutrophils during the early pregnancy. Shirasuna K et al. (2015) When pregnancy is established, interferon tau (IFNT), a well-known pregnancy recognition signal in ruminants, is secreted by embryonic trophoblast cells and acts within the uterus to prepare for pregnancy. IFNT acts as an endocrine factor on the corpus luteum (CL) to induce refractory ability against the luteolytic action of PGF2a. Hypothesising that IFNT may influence not only the uterine environment but also the CL in cows via local or peripheral circulation, we investigated qualitative changes in the CL of pregnant cows during the maternal recognition period (day 16) and the CL of non-pregnant cows. The CL of pregnant animals had higher number of neutrophils, and the expression of interleukin (IL)-8 mRNA and its protein was higher as well, as compared with the CL of non-pregnant animals. Although IFNT did not affect progesterone secretion and neutrophil migration directly, it stimulated IL-8 mRNA expression on luteal cells influenced the neutrophils, resulting in the increased migration of IFNT-activated neutrophils. Moreover, both IFNT-activated neutrophils and IL-8 increased progesterone secretion from luteal cells in vitro. Our novel finding was the increase in neutrophils and IL-8 within the CL of pregnant cows, suggesting the involvement of IFNT function within the CL toward establishment of pregnancy in cows. The present results suggest that IFNT up-regulates neutrophil numbers and function via IL-8 on luteal cells in early pregnant CL, and that both neutrophils and IL-8, stimulated by IFNT, are associated with increase in progesterone concentrations during the maternal recognition period in cows.//////////////////
Endocrine Delivery of Interferon Tau Protects the Corpus Luteum from Prostaglandin F2 Alpha-Induced Luteolysis in Ewes. Antoniazzi AQ et al. Paracrine release of ovine interferon tau (oIFNT) from the conceptus alters release of endometrial prostaglandin F2 alpha (PGF) and prevents luteolysis. Endocrine release of oIFNT into the uterine vein occurs by Day 15 of pregnancy and may impart resistance of the corpus luteum (CL) to PGF. It was hypothesized that infusion of recombinant oIFNT (roIFNT) into the uterine or jugular veins on Day 10 of the estrous cycle would protect the corpus luteum (CL) against exogenous PGF-induced luteolysis. Osmotic pumps were surgically installed in 24 ewes to deliver BSA (n = 12) or roIFNT (n = 12; 200 g/day) for 24 h into the uterine vein. Six ewes in each treatment group received a single injection of PGF (4 mg/58 kg body weight) 12 h following pump installation. In a second experiment, BSA or roIFNT was delivered at 20 or 200 g/day into the uterine vein or 200 g/day into the jugular vein for 72 h in 30 ewes. One half of these ewes received an injection of PGF 24 h following pump installation. Concentrations of progesterone in serum declined in BSA-treated ewes injected with PGF, but were sustained in all ewes infused with 20 g/day of IFNT into the uterine vein and 200 g of roIFNT into the jugular vein followed 24 h later with injection of PGF. All concentrations of roIFNT and modes of delivery (uterine or jugular vein) increased luteal concentrations of IFN-stimulated gene (i.e., ISG15) mRNA. Infusion of 200 g of IFNT over 24 h induced greater mRNA concentrations for cell survival genes, such as, BCL2-like 1 (BCL2L1 or Bcl-xL), serine/threonine kinase (AKT) and X-linked inhibitor of apoptosis (XIAP) and decreased prostaglandin F receptor (PTGFR) mRNA concentrations when compared to controls. It is concluded that endocrine delivery of roIFNT, regardless of route (uterine or jugular vein), effectively protects CL from the luteolytic actions of PGF by mechanisms that involve ISGs and stabilization of cell survival genes.
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