Mouse interferon produced in vivo does not inhibit the development of preimplantation mouse embryos

Expression and purification of buffalo interferon-tau and efficacy of recombinant buffalo interferon-tau for in vitro embryo development

The aim of our study was to optimize growth and induction parameters, for expression and large scale purification of functionally active buffalo interferon tau, and to study its possible impact on in vitro blastocyst development. The buffalo interferon-tau gene (BuIFN-T1) bearing gene bank accession No. JX481984, with signal sequence, was obtained through polymerase chain reaction (PCR) from bovine early embryos and was cloned into pJET vector. After being verified, the fragments without signal sequence, were inserted into the expression vector pET-22b and the recombinant plasmid was induced to express the recombinant protein in a prokaryotic expression system. The recombinant BuIFN-T was confirmed by SDS-PAGE and Western blot and subjected to three steps of large scale purification using His Affinity chromatography, Anion Exchange chromatography and Gel Filtration chromatography. The purified recombinant BuIFN-T protein was validated by mass spectroscopy analysis. To examine the effect of recombinant BuIFN-T protein on developmental competency of buffalo embryos, purified recombinant BuIFN-T protein was added to in vitro embryo culture medium (at concentration of 0, 1μg/ml, 2μg/ml, 4μg/ml) for 9days. Addition of recombinant BuIFN-T (2μg/ml) significantly improved the rate of blastocyst production, 45.55% against 31.1% control (p<0.01). Here we conclude that the recombinant BuIFN-T was successfully purified to homogeneity from a prokaryotic expression system and it significantly increased the blastocyst production rate in buffalo. These findings suggest a potential impact of IFN-T in promoting embryonic growth and development.

Possible Role of Interferon-.TAU. on In Vitro Development of Bovine Embryos

The effect of interferon-tau on in vitro development of bovine embryos was investigated. After in vitro fertilization, embryos developed to the morula stage were cultured for 3 days in TCM-199 or CR1 medium containing BSA or FCS supplemented with or without recombinant IFN-tau produced by a baculovirus expression system. Addition of baculovirus-expressed IFN-tau (100 ng/ml) significantly promoted development to the blastocyst stage in both culture media. Addition of E. coli expressed IFN-tau (2 microg/ml) also significantly promoted the embryonic development. Supplementation of BSA or FCS did not affect the growth-promoting effect of IFN-tau. To determine whether the growth-promoting effect of IFN-tau is related to the interferon type I receptors that bind to type I interferon such as IFN-alpha, embryos were cultured with IFN-alpha. Although IFN-alpha significantly promoted the development, a much higher concentration (25 microg/ml) was required than IFN-tau. A reverse transcription polymerase chain reaction analysis revealed the expression of mRNA encoded type-I IFN receptor subunit from morula to blastocyst stage embryos. The overall results suggest a novel function for IFNs in promoting embryonic development and the effect may be related to type-I IFN receptor expressed in the early stages of preimplantation embryos.

Immune interferon gamma inhibits translational mobility of a plasma membrane protein in preimplantation stage mouse embryos: a T-helper 1 mechanism for immunologic reproductive failure

OBJECTIVE

Immune interferon gamma adversely affects mouse embryo development and has been proposed as a mediator of reproductive failure involving T-helper 1 immunity. We hypothesized that one mechanism by which interferon gamma could exert an adverse effect on embryos was by altering plasma membrane organization and transmembrane protein mobility.

STUDY DESIGN

The fluorescence photobleaching recovery technique was used to measure the effect of the T-helper 1 cytokine interferon gamma on the translational mobility of a specific embryonic surface glycoprotein recognized by the monoclonal antibody S75.

RESULTS

Compared with controls interferon gamma significantly decreased the fractional mobility of fluorescein isothiocyanate S75 in one- and two-cell mouse embryos.

CONCLUSION

Interferon gamma may alter plasma membrane domains or cytoskeletal organization in early-stage embryos. By restricting plasma membrane protein mobility interferon gamma could effect T-helper 1-mediated reproductive failure.

Induction of embryonic major histocompatibility complex antigen expression by gamma-IFN

Preimplantation mouse embryos were incubated in vitro with mouse recombinant gamma-interferon (IFN). The effect of the gamma-IFN on major histocompatibility complex (MHC) class I antigen expression was tested using an ELISA procedure. It was found that there is a doubling of Db antigens and a tripling of Qa-2 antigens on C57BL/6 mouse embryos cultured from the 8-cell stage for 24 h in the presence of 10(5) units/ml gamma-IFN. The effect of gamma-IFN on the rate of preimplantation embryonic development was tested by culturing 2-cell embryos for 48 h and 8-cell embryos for 24 h in the presence of varying concentrations of gamma-IFN up to 10(6) units/ml. Two methods were used to assess the cell number per embryo after the culture period: incorporation of [3H]thymidine into DNA, and direct counting of nuclei in fixed and stained embryos. Both methods showed that treatment with gamma-IFN increases the rate of development of preimplantation mouse embryos. Since rate of preimplantation embryonic development is genetically controlled by the Ped gene, it is suggested that gamma-IFN has a direct effect on the Ped gene phenotype of preimplantation mouse embryos.

Development and DNA polymerase activities in cultured preimplantation mouse embryos: comparison with embryos developed in vivo

Embryos from superovulated female mice that developed in vitro from the two-cell stage were compared with in vivo embryos with respect to yield of blastocytes, number and types of cells, morphology in histologic section, and DNA polymerase activities. Significantly more embryos developed into blastocytes in vitro (93%) than in vivo (18%). Inner cell mass (ICM) cells comprised approximately 30% of total cells in late morula/early blastocyst stage embryos developed either in vitro or in vivo. However, the in vitro embryos developed approximately half the number of total cells as in vivo embryos, did not develop endoderm, and did not develop abembryonic trophoblast cells with morphologic characteristics of late preimplantation in vivo embryos. DNA-dependent DNA polymerase activities in in vitro embryos decreased in correspondence with the decrease in cell number resulting in per cell levels comparable to in vivo embryos. In contrast, the poly (A).oligo(dT)-dependent DNA polymerase activity was the same in embryos developing either in vitro or in vivo, indicating different regulatory mechanisms for the two enzyme activities. A variety of nutrients and growth factors in the culture medium did not increase cell numbers or DNA polymerase activities in embryos cultured for 3 days; extending the culture an additional 24 hours resulted in a loss of ICM cells and decreases in both DNA polymerase activities. These results show that the retarded growth of embryos in vitro is equally distributed between ICM and trophoblast, is not reversed by culture conditions that include serum growth factors, and is not due to decreased cellular levels of DNA polymerase activities.

Macrophages and migratory cells in endometrium relevant to implantation

The implantation of an appropriately developed embryo into a suitably conditioned uterine lining depends on the synchronous maturation of the preimplantation embryo and uterine lining. The pre- and postimplantation embryo also requires protection from immunocompetent maternal immune effectors. Preimplantation embryo development is affected by genotype, intercellular communication and autocrine growth factors (polyamines, TGF-alpha, TGF-beta 1, PAF). Factors of maternal origin may also enhance embryo development (EGF, TGF-alpha, TGF-beta 1, IGF, polyamines). The preimplantation embryo signals its presence to the mother by release of factor(s) such as IFN-alpha-II and a PAF-like factor. PAF may induce EPF in the mother and enhances vascular permeability at the implantation site. Uterine or peritoneal leukocytosis may inhibit development via toxic effects of lymphokines/monokines (IL-2, IL-1?, IFN-gamma, TNF-alpha). Immunoprotection of the preimplantation embryo is conferred by embryo derived maternal factors (EPF, T-cell suppressor factors). The uterus is receptive during a limited period of time (implantation window) and the substrate adhesion molecules produced by uterine and embryonic trophectoderm cells are crucial for the initial stages of implantation. At implantation, trophoblast expression of MHC and non-MHC antigens is shut off and both immunocompetent maternal cells (macrophages, dendritic cells, granulocytes, IELs, immunocytes) and lymphatics become sparse at implantation sites. Peri-implantation cytokines of maternal origin, such as CSF-1, GM-CSF and IGF-1 binding protein, are probably important for trophoblast growth and development. Immuno-protection of the embryo at this stage may be mediated by embryo derived factors that inactivate macrophages and by a population of large, hormone dependent Lyt 2+ (CD8+) suppressor cells. It is possible that these CD8+ cells respond to progesterone and secrete molecules that inactivate natural effector (NK-type) cells against trophoblast. Prostaglandins (PGE2) may play a brief role in immunosuppression at the time of implantation but its role is probably more important with respect to the decidual response. Defects in the pre- and peri-implantation stages of pregnancy may lead to delayed failure in the form of clinical miscarriage.