Modulation of maternal immune system during pregnancy in the cow

There is a molecular crosstalk between the trophoblast and maternal immune cells of bovine endometrium. The uterine cells are able to secrete cytokine/chemokines to either induce a suppressive environment for establishment of the pregnancy or to recruit immune cells to the endometrium to fight infections. Despite morphological differences between women and cows, mechanisms for immune tolerance during pregnancy seem to be conserved. Mechanisms for uterine immunesuppression in the cow include: reduced expression of major histocompatability proteins by the trophoblast; recruitment of macrophages to the pregnant endometrium; and modulation of immune-related genes in response to the presence of the conceptus. Recently, an eGFP transgenic cloned embryo model developed by our group showed that there is modulation of foetal proteins expressed at the site of syncytium formation, suggesting that foetal cell can regulate not only by the secretion of specific factors such as interferon-tau, but also by regulating their own protein expression to avoid excessive maternal recognition by the local immune system. Furthermore, foetal DNA can be detected in the maternal circulation; this may reflect the occurrence of an invasion of trophoblast cells and/or their fragment beyond the uterine basement membrane in the cow. In fact, the newly description of exosome release by the trophoblast cell suggests that could be a new fashion of maternal-foetal communication at the placental barrier. Additionally, recent global transcriptome studies on bovine endometrium suggested that the immune system is aware, from an immunological point of view, of the presence of the foetus in the cow during early pregnancy.

IFPA Meeting 2010 Workshop Report I: Immunology; ion transport; epigenetics; vascular reactivity; epitheliochorial placentation; proteomics

Workshops are an important part of the IFPA annual meeting. At IFPA Meeting 2010 there were twelve themed workshops, six of which are summarized in this report. 1. The immunology workshop focused on normal and pathological functions of the maternal immune system in pregnancy. 2. The transport workshop dealt with regulation of ion and water transport across the syncytiotrophoblast of human placenta. 3. The epigenetics workshop covered DNA methylation and its potential role in regulating gene expression in placental development and disease. 4. The vascular reactivity workshop concentrated on methodological approaches used to study placental vascular function. 5. The workshop on epitheliochorial placentation covered current advances from in vivo and in vitro studies of different domestic species. 6. The proteomics workshop focused on a variety of techniques and procedures necessary for proteomic analysis and how they may be implemented for placental research.

Initial development of bovine placentation (Bos indicus) from the point of view of the allantois and amnion

The aim of this study was to perform a morphological characterization of the initial bovine placental development, between 20 and 70 days post-insemination (p.i.), with emphasis on the differentiation of the allantois and amnion. After collection, the conceptuses were dissected, macroscopically measured and photographically documented. The extraembryonic membranes were cut into fragments measuring 5 cm(2), and then fixed in 4% paraformaldehyde for analysis using light microscopy, and in 2.5% glutaraldehyde for use in scanning and transmission electron microscopy. The extraembryonic and fetal membranes presented variable degrees of development throughout the periods analysed. The macroscopic appearance of vascularization of the allantois, its attempt to merge with the chorium and the effective appearance of the first cotyledons in development were the events observed from 30 to 40 days of pregnancy. The measurements of the amnion increased gradually as gestation developed. The allantoic epithelia presented cellular dimorphism from 20 to 25 days of pregnancy, but was shown to be immature from 60 to 70 days of pregnancy.

299 DEVELOPMENTAL COMPETENCE OF TRANSGENIC BOVINE EMBRYOS RECONSTRUCTED BY NUCLEAR TRANSFER USING MEIOSIS-BLOCKED OOCYTES

Recent progress in animal cloning by nuclear transfer (NT) has made it feasible to produce transgenic animals using genetically modified cell lines. Healthy cells and competent oocytes are needed to maximize the number of transgenic calves produced. Oocyte maturation plays a central role in oocyte competence. Prematuration inducing meiosis block is, therefore, a possible tool in transgenesis, because it allows further optimization of oocyte maturation protocols. In field conditions, it is not always possible to precisely control timing between oocyte collection and NT procedures. Therefore, temporarily and reversibly blocking maturation may also be used as a strategy to optimize cloning protocols. The aim of this study was to analyze the developmental competence of embryos reconstructed by NT using cells modified genetically as nuclei donors and oocytes submitted, or not, to meiosis block as cytoplasts. The hypothesis was that blocking meiosis does not alter the embryonic developmental physiology nor production of transgenic cloned bovine blastocysts. Ovaries were collected at a slaughterhouse and follicles between 3 and 6 mm were aspirated. Oocytes were divided into 2 groups. The first group (CTR, n = 145) was matured in vitro (IVM) with TCM-199 supplemented with 10% fetal calf serum, 5.0 µg mL–1 of LH, 0.5 µg mL–1 of FSH, 0.2 mm pyruvate, and 10 µg mL–1 of gentamicin for 18 h at 38.5�C under 5% CO2 in a humidified atmosphere. The second group (BL, n = 153) had meiosis blocked by in vitro culture with TCM-199 supplemented with 0.2 mm pyruvate, 10 µg mL–1 of gentamicin, and 10 µm butyrolactone I for 24 h, and then matured in vitro for 18 h. Parthenogenetic embryos resulted from meiosis-blocked and non-blocked oocytes were used as controls for the respective groups of NT embryos. After IVM, oocytes from both groups were reconstructed using bovine fetal fibroblasts transduced previously with a lentivirus and expressing the green fluorescent protein gene. The effect of treatment on fusion rates in cloned embryos, cleavage rates on Day 2, and blastocyst rates on Day 7 of in vitro culture of cloned and parthenogenetic embryos from CTR and BL groups were analyzed by chi-square test at 5% significance. Meiosis block did not affect fusion rates (n = 68, 46.90% and n = 86, 56.21% for CTR and BL cloned groups, respectively). Cleavage rates did not differ between cloned groups (n = 43, 63.24% and n = 49, 56.98% for CTR and BL groups) or between parthenogenetic groups (n = 15, 50% and n = 21, 70% for CTR and BL groups). Also, no difference was observed in blastocyst rates between cloned groups (n = 5, 7.35% and n = 6, 6.98% for CTR and BL groups) and between parthenogenetic groups (n = 11, 36.67% and n = 9, 30% for CTR and BL groups). It was concluded that meiosis block does not affect embryo development to the blastocyst stage. It is suggested that temporarily blocking meiosis may be a useful strategy to optimize NT protocols. FAPESP, Brazil.

Placentation in cloned cattle: Structure and microvascular architecture

To elucidate the morphological differences between placentas from normal and cloned cattle pregnancies reaching term, the umbilical cord, placentomes and interplacentomal region of the fetal membranes were examined macroscopically as well as by light and scanning electron microscopy. In pregnancies established by somatic nucleus transfer (NT), the umbilical cord and fetal membranes were edematous. Placentomal fusion was common, resulting in increased size and a decreased number of placentomes. Extensive areas of the chorioallantoic membrane were devoid of placentomes. An increased number of functional or accessory microcotyledons (<1 cm) were present at the maternally oriented surface of fetal membranes. Extensive areas of extravasated maternal blood were present within the placentomes and in the interplacentomal region. The crypts on the caruncular surface were dilated and accommodated complexes of more than one primary villus, as opposed to a single villus in non-cloned placentae. Scanning electron microscopy of blood vessel casts revealed that there was also more than one stem artery per villous tree and that the ramification of the vessels failed to form dense complexes of capillary loops and sinusoidal dilations as in normal pregnancies. At the materno-fetal interface, however, the trophoblast and uterine epithelium had normal histology. In conclusion, the NT placentas had a range of pathomorphological changes; this was likely associated with the poor clinical outcome of NT pregnancies.

71 WHAT IS THE UTERINE RESPONSE IN A CLONED BOVINE PREGNANCY?

Bovine has a synepitheliochorial placenta and characteristically there is no invasion of the trophoblast, but there is migration of the binucleate trophoblast giant cells into the maternal endometrium. The feto-maternal interface occurs in placentome where a tridimensional organization permits interactions between maternal epithelium and trophoblast, and in the intercaruncular area it is possible to observe a few mini-placentomes and the uterine glands opening. The objective of the present investigation was to study the morphological aspects of the uterus in bovine that had a cloned cattle gestations to understand the differences with natural gestation. The uterus and fetal membranes from natural and cloned cattle gestations were collected, fixed in 10% formaldehyde, processed, and stained for light microscopy and immunohistochemistry. The morphological differences observed in the surrogate uterus were: extensive areas without placentome, hemorrhagic uterine areas, caruncular fusion giving a reduced number of caruncules, increase in size and weight (megacaruncules), and a significant number of mini-caruncules giving miniplacentomes (diameter < 1 cm). In particular the mini-placentome showed functional trophoblastic cells with PAS+ granules in the binucleate trophoblast giant cells and an intense subepithelial capillary organization in maternal and fetal sides. The normal and clone placentomal cell populations were analyzed throughout pregnancy. The population of tetraploid and diploid trophoblastic cells was stained; detached cell cycle and DNA content was measured in FL2 using a FACscalibur flow cytometric system. We determined the percentage of cells in apoptosis (sub-G1), quiescent cells (G0/G1), synthesis (S), and proliferative cells (G2/M) with the aid of ModFit software. In addition, a cell cycle differential analysis was performed, and the tetraploid population presented statistical differences in cell cycle phases and populations relative to the apoptosis rate for the first (7.5 � 3.1%), second (15.2 � 5.0%) and third (17.3 � 4.3%) trimesters. The number of apoptotic cells increased significantly during pregnancy stages. The results showed that first trimester presented the majority of its cells in the G0-G1 phase, starting the cell cycle. On the other hand, the second and third trimesters presented the majority of their cells in the G2-M phase, ending the cell cycle. The relationship between cell cycle phases/rate of apoptosis in mononucleate cells, days of normal and cloned pregnancy, the number of binucleate cells, and their metabolic activity as well as their developmental kinetics could be important data in several studies that involve placental development in natural pregnancy or that derived from laboratory-manipulated embryos. This work was supported by FAPESP and CNPq.

Binucleate trophoblast giant cells in the water buffalo (Bubalus bubalis) placenta

The binucleate trophoblast giant cells (BNC) of the water buffalo, Bubalus bubalis, placenta were studied, with emphasis on the synthesis of BNC-specific proteins. Placentomal tissues of 27 water buffalos (2-10 months of pregnancy) were processed for light and electron microscopy. The frequency of BNCs was 20% of the trophoblastic cells in 2-3-month placentas and increased to 27% in the later stages. Ultrastructurally, binucleate cells displayed a prominent granular endoplasmic reticulum and Golgi apparatus, typical of cells involved with protein synthesis and exportation. The buffalo BNCs contained periodic acid-Schiff (PAS)-positive granules and reacted with antisera against bovine placental lactogen, prolactin-related protein-I, and pregnancy-associated glycoproteins. Lectin histochemistry with Dolichos biflorus agglutinin, Vicia villosa agglutinin, and Phaseolus vulgaris leucoagglutinin showed specific staining of BNCs. Different stages of BNC migration and fusion with uterine epithelial cells were observed. Trinucleate feto-maternal hybrid cells were the typical outcome of cell fusions. These cells underwent degeneration, with typical morphological features of apoptosis. The results revealed a strong homology between water buffalo and cattle BNCs concerning cell morphology, protein expression, glycosylation pattern, and characteristics of cell migration and fusion.