Effects of Interferon-Tau on Cortisol Production by the Bovine Endometrial Tissues.

Abstract

Glucocorticoids (GCs) are well known as anti-inflammatory agents limiting the production of cytokines and prostaglandin (PG)s in various target organs. Access of GCs to GC receptor (GC-R) in target tissues is regulated by two 11β-hydroxysteroid dehydrogenases (11-HSD1 and 2). We previously demonstrated that cyclic bovine endometrium expresses 11-HSD1 mRNA, and converts biologically inactive cortisone into cortisol. Moreover, we have shown that cortisol suppressed PGF2α without affecting PGE2 production in the cyclic bovine endometrium. Interferon-τ (IFN-τ) produced by the trophoblast at the time of recognition of pregnancy acts on maintaining corpus luteum (CL) function. Furthermore, some previous study demonstrated that in ewes the plasma concentrations of cortisol increased in response to IFN-τ. Therefore, we suggest that cortisol acts as a luteoprotective factor by selectively suppressing luteolytic PGF2α production by the pregnant bovine endometrium as INF-τ mediator. The aim of the present study was to determine if IFN-τ affects cortisol production and secretion in bovine endometrial tissues during the early pregnancy comparing to the responsible days of the estrous cycle. In Exp. 1., GC-R, 11-HSD1 and 11-HSD2 expressions on the gene (mRNA) and protein levels in pregnant (Days 16-18 after insemination) and nonpregnant (Days 16-18 after ovulation) endometrial strips were measured by using real time RT-PCR and Western-Blot analysis, respectively. In Exp. 2. (tissue culture study), the endometrial explants were taken from cows on Days 16-18 of the cycle and pregnancy. Endometrial slices from both groups of cows were incubated for 12 h with cortisone (30 nM) and/or IFN-τ (30 ng/ml), and then 11-HSD1 activity was evaluated by measuring cortisol level. Moreover, the endometrial stromal and epithelial cells were isolated enzymaticaly from bovine uteri in the early luteal stage of estrous cycle (Exp. 3., cell culture study). The cells were seeded in 48-well cluster dishes and then were exposed to cortisone (30 nM) and/or IFN-τ (30 ng/ml). After incubation, the conditioned media were collected, and then 11-HSD1 activity was evaluated by measuring cortisol level. Endometrial GC-R and 11-HSD1 mRNA expressions were higher from pregnant than those from non-pregnant cows (P<0.05). Moreover, 11-HSD2 mRNA expression was lower in cyclic cows than that in pregnant cows. Protein expression for 11-HSD1 was significantly higher in the tissues from pregnant than those from non-pregnant cows (P<0.05). 30 ng/ml IFN-τ significantly increased 11-HSD1 activity and cortisol secretion in endometrial explants, and in both stromal and epithelial cells compare to control (P<0.05). The overall results suggest that the level of cortisol is locally regulated by INF-τ in the pregnant bovine endometrium by up-regulating 11-HSD1 expression and activity. Based on our previous and present findings, IFN-τ seems to suppress PGFα secretion by up-regulating cortisol activation, resulting in the maintenance of the CL during early pregnancy in cattle. Supported by Grants-in-Aid for Scientific Research from the Polish Ministry of Sciences and Higher Education (N308 3279 33) and Japan Society for the Promotion of Science (JSPS, No.18380166). MM, DJS and KO were supported by the Japanese-Polish Joint Research Project under the agreement between JSPS and Polish Academy of Sciences. (poster)