Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5523006 | Theriogenology | 2017 | 7 Pages |
â¢A specific induction of IFNÏ induced genes in the liver Day 18.â¢ISG 15, MX 1, MX 2 and OAS 1 higher in a liver biopsy.â¢OAS1 protein was localized in the parenchymal cells (hepatocytes).â¢In vitro primary hepatocytes react to IFNÏ in the presence or absence of progesterone.â¢Possible causal importance as metabolic answer of the pregnant mother.
Interferon-tau (IFNÏ) is the conceptus derived specific early pregnancy signal in bovidae. Locally, IFNÏ induces an IFNÏ specific gene expression (ISG) in endometrial cells and by this it averts luteolysis of the corpus luteum (CL) by suppressing prostaglandin production. Moreover, it was shown that IFNÏ also induces ISG in the liver in pregnant sheep and in liver biopsies from Holstein Friesian heifers on Day 18 of pregnancy. The objective of the present study was to confirm increased hepatic ISG in vivo on Day 18 of pregnancy and to prove if hepatocytes and not non-parenchymal cells react to IFNÏ by using immunohistochemistry and primary bovine hepatocytes stimulated in vitro with recombinant bovine IFNÏ. For the animal experiment, Angus heifers (n = 12) were cycle synchronized and the Day of ovulation (Day 0) was defined by ovarian ultrasonography and verified by progesterone < 0.1 ng/ml. Heifers were artificially inseminated either with sperm (n = 9) or with seminal plasma (mock control, n = 3). Early pregnancy was defined and detected by progesterone and pregnancy associated glycoprotein (PAG) concentration in blood before and after induced luteolysis by a PGF-injection on Day 21 in n = 3 inseminated heifers. A liver biopsy was taken on Day 18 for the analysis of gene (ISG 15, MX 1, MX 2 and OAS 1) and protein (OAS1) expression using qPCR and immunohistochemistry, respectively. Primary bovine hepatocytes were collected from bull liver using a two-step collagenase perfusion, cultured short-term in a monolayer and stimulated with IFNÏ. Thereafter, gene expression was measured by qPCR. In liver biopsies obtained from pregnant heifers ISG was numerically higher expressed compared to biopsies from non-pregnant heifers. Furthermore, the OAS 1 protein expression was localized in hepatocytes on Day 18 of pregnancy. In vitro, primary bovine hepatocytes showed an increased mRNA expression of ISG after IFNÏ stimulation. In conclusion, the findings confirm that IFNÏ induces ISG in the parenchymal part of the liver in early pregnancy of cattle.