Regulation of uterine immune function by progesterone--lessons from the sheep

Degeneration and apoptosis of endometrial cells in the bitch

The relationships between changes in plasma progesterone concentrations, degeneration of the luminal epithelium, the occurrence of apoptosis of endometrial cells and endometrial leucocyte populations in the bitch were determined. Mature bitches (n = 15) were euthanized and necropsied when in diestrus (Days 7-75, n = 12) or in anestrus (Days 10, 32 and 53). Degeneration of the luminal epithelium was observed in bitches in late diestrus (Days 38-75, n = 5) when plasma progesterone concentrations were decreasing and in anestrus (Days 10 and 32, n = 2) when plasma progesterone concentrations were < 0.5 ng/mL. Endometrial leucocyte populations increased after degeneration of the luminal epithelium (around Day 42 of diestrus). Apoptosis was mainly observed in the basal glandular epithelial cells and endothelial cells of blood capillaries in all except anestrous bitches. Very few apoptotic cells were found in the superficial glandular epithelial cells and stromal cells. Higher apoptotic indices were detected in the basal glandular epithelium on Days 12-42 of diestrus than at other stages. Therefore, apoptosis of glandular basal epithelial cells occurred mainly in early diestrus, degeneration of cells of the luminal epithelium occurred from mid-diestrus to early anestrus, and the increase in leucocyte numbers may have been a consequence and not a cause of luminal epithelial degeneration.

Prostaglandin F2alpha Upregulates Uterine Immune Defenses in the Presence of the Immunosuppressive Steroid Progesterone

PROBLEM

Uterine infections often develop in some livestock species during the first luteal phase postpartum. Exogenous prostaglandin F(2alpha) (PGF(2alpha)) induces luteolysis, reduces progesterone, and enables the uterus to resolve infections. However, the effects of PGF(2alpha) on luteal function and on immune functions are confounded. These effects must be disentangled to determine whether alternatives to antibiotic treatments can be successfully developed.

METHOD OF STUDY

Treatments were in a 2 x 2 x 2 factorial arrangement. Main effects were ovariectomy or sham on day 0 (i.e. estrus), exogenous progesterone or sesame oil from day 0 to 11, and exogenous PGF(2alpha) or saline on day 9. Intrauterine inoculations with Arcanobacterium pyogenes and Escherichia coli were administered on day 6.

RESULTS

Ewes treated with exogenous PGF(2alpha) either did not have uterine infections, infections were less severe, or infections were resolving when uteri were examined on day 12, despite increased progesterone.

CONCLUSIONS

Exogenous PGF(2alpha) has effects on the resolution of uterine infections that are independent of its effects on luteal progesterone production.

Progesterone regulates mouse dendritic cells differentiation and maturation

Progesterone, an important factor in the maintenance of gestation in humans and animals, has been demonstrated to lower immune response during pregnancy [Siiteri PK, Stites DP, Immunologic and endocrine interrelationships in pregnancy, Biol Reprod, (1982); Watnick AS, Russo RA, Survival of skin homografts in uteri of pregnant and progesterone-estrogen treated rats, Proc Soc Exp Biol Med, (1968)], which is one of many hypotheses trying to explain fetal tolerance. Because dendritic cells (DCs) play an important role in the initiation of immune response, we examined the effects of progesterone on the differentiation and maturation of DCs derived from mouse bone marrow cells. Our data suggest that progesterone may be involved in the maternal immune response by modulating DC differentiation, maturation and function.

Galectin-15 in ovine uteroplacental tissues

Galectin-15 is the newest member of a secreted beta-galactoside-binding lectin family. The galectin-15 gene is expressed specifically by the endometrial luminal epithelium (LE) and superficial ductal glandular epithelium (sGE) of the ovine uterus. The proposed extracellular role of secreted galec7tin-15 is to regulate implantation and placentation by functioning as a heterophilic cell adhesion molecule between the conceptus trophectoderm and endometrial LE, while that of intracellular galectin-15 is to regulate cell survival, differentiation and function. The present study determined galectin-15 expression in uteroplacental tissues during gestation and in the postpartum uterus. In the uterine lumen, secreted galectin-15 was found as multimers, particularly on days 14 and 16 of pregnancy. In the endometrial epithelium and conceptus trophectoderm, intracellular galectin-15 protein was found associated with crystalline structures. Between days 20 and 120 of pregnancy, galectin-15 mRNA was expressed specifically by the LE and sGE of the intercaruncular endometrium of ewes. Immunoreactive galectin-15 protein was most abundant in the trophectoderm with lower levels in the endometrial LE and sGE. Galectin-15 protein was detected in allantoic fluid, but not in amniotic fluid. After parturition, galectin-15 mRNA declined in the endometrium from postpartum day (PPD) 1 to 28 and exhibited a variegated expression pattern in the LE and sGE. These results indicate that galectin-15 is synthesized and secreted throughout gestation by the endometrial LE/sGE and is absorbed by the placenta and forms crystals within the trophectoderm, whereas the remainder is cleared into the allantois after being transported into the fetal circulation via the placental areolae. Based on the biological properties of other galectin family members, galectin-15 is hypothesized to have biological roles in conceptus-endometrial interactions, uterine immune and inflammatory responses, and placental morphogenesis and function.

Uterine Response to Multiple Inoculations with Arcanobacterium pyogenes and Escherichia coli in Nulliparous Ewes

PROBLEM

Uterine infections seem more severe in nulliparous animals. Our objective was to determine whether intrauterine inoculation of nulliparous ewes with Arcanobacterium pyogenes and Escherichia coli would produce an antibody response and reduce the severity of subsequent infections.

METHOD OF STUDY

Nulliparous ewes (n = 9/treatment) received (i) 'primary intrauterine inoculation' with phosphate-buffered saline (PBS) and 'secondary intrauterine inoculation' with PBS; (ii) primary PBS-secondary 75 x 10(7) cfu of A. pyogenes and 35 x 10(7) cfu of E. coli (PBS-Bacteria); (iii) primary bacteria-secondary PBS; or (iv) primary bacteria-secondary bacteria (Bacteria-Bacteria).

RESULTS

Inoculations evoked an antibody response. Postmortem examinations 6 days after the secondary inoculation indicated that PBS-treated ewes did not develop uterine infections, but all bacteria-treated ewes did. Infections were either less severe or closer to resolution in Bacteria-Bacteria than they were in PBS-Bacteria ewes.

CONCLUSIONS

Intrauterine inoculation of nulliparous ewes with A. pyogenes and E. coli evokes an antibody response that may help the uterus reduce the severity of subsequent infections.

Immunophenotypical Characterization of Lymphocyte Subpopulations of the Uterus of Non-pregnant and Pregnant Goats

The increased susceptibility during pregnancy to certain pathogens that cause abortions may be related to changes in the distribution and phenotype of lymphocyte subpopulations in the uterus. Histological, electron microscopic and immunocytochemical techniques were used in this study to examine whether such variations occur in different stages of the reproductive cycle of goats. The study of non-pregnant goats showed that most uterine lymphocytes were T cells and displayed both an intraepithelial and stromal distribution. CD8+ T lymphocytes were more numerous than CD4+ T lymphocytes. In the endometrial epithelium two lymphocyte subpopulations were observed: non-granulated CD2+ CD8+ T lymphocytes and granulated CD2+ CD8- T lymphocytes. During gestation, no lymphocytes were observed in the placentomal area, while a decreased number of T lymphocyte subpopulations were found in the inter-placentomal area. In the inter-caruncular epithelium, non-granulated CD2+ CD8+ T lymphocytes disappeared, whereas the granulated CD2+ CD8- T lymphocyte subpopulations increased their number and changed their morphology.

Identification and cloning of caprine uterine serpin

The uterine serpins have been described in sheep, cattle, and pigs as a highly diverged group of the large superfamily of serpin proteins that typically function as serine proteinase inhibitors. Here, the range of species that possess and express a uterine serpin gene is extended to the goat. Sequencing of cDNA amplified from total RNA from a pregnant goat at day 25 of pregnancy resulted in a 1,292 bp full-length consensus cDNA sequence for caprine uterine serpin (CaUS). The predicted amino acid sequence of the caprine precursor showed 96%, 82%, 55%, and 56% identity to OvUS, BoUS, PoUS1, and PoUS2, respectively. The signal peptide extends from amino acids 1 to 25, resulting in a secreted protein of 404 amino acids and 46,227 Mr (excluding carbohydrate). Both the goat and sheep uterine serpins have a nine amino acid insert in the Helix I region that is not found in bovine or porcine uterine serpins. A total of 13 amino acids in CaUS are different than those for the nearest homologue, ovine uterine serpin. One of these is in the site of cleavage of the signal sequence, where a single nucleotide substitution (G --> C) changed the cysteine for the sheep, bovine, and porcine genes to a serine. In addition, the amino acid at the putative P1-P1' site (the scissile bond for antiproteinase activity) is a valine for CaUS, BoUS, PoUS1, and PoUS2 versus an alanine for OvUS. The hinge region of all five of the uterine serpins (P17-P9) is distinct from the consensus pattern for inhibitory sequences and it is unlikely, therefore, that the uterine serpins possess prototypical proteinase inhibitory activity. The goat uterine serpin was immunolocalized to the glandular epithelium of the endometrium from a pregnant nanny at day 25 of pregnancy. There was also immunoreactive product in scattered luminal epithelial cells. No immunoreaction product was detected in endometrium from a nanny at day 5 of the estrous cycle. Western blotting of uterine fluid collected from the pregnant uterine horn of a unilaterally-pregnant goat revealed the presence of a protein band at Mr approximately 56,000 that reacted with monoclonal antibody to OvUS. In conclusion, the range of species in which uterine serpins are present and expressed in the uterus includes the goat in addition to the previously described sheep, cow, and pig. In all of these species, the uterine serpin is derived primarily from glandular epithelium, is secreted into the uterine lumen, and contains sequence characteristics suggesting it is not an inhibitory serpin.

Actions of progesterone on uterine immunosuppression and endometrial gland development in the uterine gland knockout (UGKO) ewe

In ewes, the uterine gland knockout (UGKO) phenotype is caused by neonatal exposure to norgestomet to arrest uterine gland development and produce an adult which has a uterus characterized by the lack of endometrial glands. Since endometrial glands in the sheep produce the lymphocyte-inhibitory protein, ovine uterine serpin (OvUS), an experiment was conducted with ewes of the UGKO phenotype to evaluate whether the inhibitory actions of progesterone on tissue rejection responses in utero are dependent upon the presence of endometrial glands. Control and UGKO ewes were ovariectomized and subsequently treated with either 100 mg/day progesterone or corn oil vehicle for 30 days. An autograft and allograft of skin were then placed in each uterine lumen and treatments were continued for an additional 30 days before grafts were examined for survival. All autografts survived and had a healthy appearance after histological analysis. Allografts were generally rejected in ewes treated with vehicle but were present for hormone-treated ewes, regardless of uterine phenotype. Analysis of the histoarchitecture and protein synthetic capacity of the uterus revealed that progesterone induced differentiation of endometrial glands and synthesis and secretion of OvUS in UGKO ewes. The UGKO ewes had reduced density of CD45R+ lymphocytes in the endometrial epithelium and there was a tendency for progesterone to reduce this effect in luminal epithelium. Taken together, results confirm the actions of progesterone to inhibit graft rejection response in utero. Responses of UGKO ewes to progesterone indicate that the hormone can induce de novo development and differentiation of endometrial glands, at least when skin grafts are in the uterus.

Antiproliferative Actions of Ovine Uterine Serpin

PROBLEM

Ovine uterine serpin (OvUS) is a member of the serine proteinase inhibitor superfamily and is the major protein produced by luminal and glandular epithelium of the sheep endometrium during mid to late pregnancy. The protein does not have prototypical proteinase inhibitory activity but can inhibit a wide variety of lymphocyte functions such as mitogen-induced proliferation and natural killer cell cytotoxicity.

METHOD OF STUDY

The antiproliferative actions of OvUS were studied.

RESULTS

It was demonstrated that, in addition to inhibiting lymphocyte proliferation, OvUS inhibits growth of two tumor cell lines (D17 and PC-3). The protein also interrupts development of pre-implantation embryos. Inhibition of cell proliferation is not universal, however, as OvUS did not inhibit growth of two non-tumorigenic cell lines (MDBK and BEND). The mechanism of action of inhibitory effects of OvUS is not known although experiments with inhibitors of protein kinase A indicate that the protein does not inhibit lymphocyte proliferation through this pathway. Moreover, the protein does not induce apoptosis.

CONCLUSIONS

The finding that OvUS has antiproliferative activity is demonstrative of the wide range of functions exerted by members of the serpin superfamily. The antiproliferative property of OvUS may reflect the role of the protein during pregnancy and may be exploitable for design of new antiproliferative drugs.

Steroidal regulation of uterine immune defenses

Progesterone suppresses uterine immune defenses and predisposes postpartum animals to nonspecific uterine infections. Progesterone can also suppress uterine eicosanoid synthesis. This effect of progesterone seems to be an important factor in the onset of uterine infections because eicosanoids can enhance uterine immune defenses. In fact, exogenous prostaglandin F(2alpha) (PGF(2alpha)), an eicosanoid that stimulates uterine PGF(2alpha) production, enhances uterine immune defenses and promotes the ability of ewes and sows to resolve uterine infections, even when progesterone is maintained at luteal phase concentrations. Prostaglandin F(2alpha) is also a proinflammatory molecule that stimulates the production of proinflammatory cytokines and may enhance uterine production of leukotriene B(4) (LTB(4)), which stimulates various neutrophil functions. Neutrophils seem to mount the initial response to bacteria that enter the uterus, and proinflammatory cytokines and LTB(4) enhance phagocytic activity of neutrophils. Even though there are clear associations among PGF(2alpha), LTB(4), proinflammatory cytokines, phagocytosis, and the ability of the uterus to resist or resolve infections, the mechanisms of action of exogenous PGF(2alpha) in mitigating the immunosuppressive effects of progesterone have not yet been defined. However, defining the PGF(2alpha) mechanisms should yield important new information that can be used to develop novel prevention and treatment strategies that do not rely on antibiotic and antimicrobial compounds for managing uterine infections.

Effect of Peptidoglycan-Polysaccharide Complex on Reproductive Efficiency in Sheep

PROBLEM

Spontaneous mastitis or induced infections mimicking mastitis reduce pregnancy rates in ruminants. The effect of immunization with either a mastitis-related pathogen component, peptidoglycan-polysaccharide (PG-PS), or killed Streptococcus pyogenes on pregnancy outcome was investigated.

METHOD OF STUDY

Ewe lambs were immunized with PG-PS (n = 50) or killed bacteria (n = 50) or were not immunized (control, n = 100). Titers of PG-PS immunoglobulin G (IgG) were detected by enzyme-linked immunosorbent assay (ELISA). Ewes were bred by rams at synchronized estrus. All immunized ewes and half of the ewes not immunized were challenged with PG-PS on day 5 after breeding. Pregnancy maintenance was evaluated.

RESULTS

Although the proportion of ewes pregnant at day 42 after breeding did not differ among treatments, the probability of pregnancy decreased with total dose of PG-PS (P < 0.05).

CONCLUSIONS

Immunization of ewe lambs with PG-PS or killed S. pyogenes did not improve pregnancy maintenance. Furthermore, the toxic streptococcal component decreased pregnancy rate in immunized sheep in a dose-dependent manner.

N-glycans of human amniotic fluid transferrin stimulate progesterone production in human first trimester trophoblast cells in vitro

AIMS

During pregnancy, the placenta produces a variety of steroid hormones and proteins. Several of these substances have been shown to exert immunomodulatory effects. Progesterone is thought to mediate some of these effects by regulating uterine responsiveness. The aim of this study was to clarify the effect of amniotic fluid transferrin and its N-glycans on the release of progesterone by first trimester trophoblast cells in vitro.

METHODS

Cytotrophoblast cells were prepared from human first trimester placentae by trypsin-DNAse dispersion of villous tissue followed by a percoll gradient centrifugation and depletion of CD45 positive cells by magnetic cell sorting. Trophoblasts were incubated with varying concentrations (50-300 microg/ml) of transferrin from human amniotic fluid and serum as well as with N-glycans obtained from amniotic fluid transferrin. Culture supernatants were assayed for progesterone by enzyme-immunometric methods.

RESULTS

The release of progesterone increased in amniotic fluid transferrin- and N-glycan-treated trophoblast cell cultures compared to untreated trophoblast cells. There was no stimulating effect of serum transferrin on the progesterone production of trophoblast cells.

CONCLUSIONS

The results suggest that amnion-transferrin and especially its N-glycans modulate the endocrine function of trophoblasts in culture by up regulating progesterone secretion.

Human amniotic fluid glycoproteins expressing sialyl Lewis carbohydrate antigens stimulate progesterone production in human trophoblasts in vitro

BACKGROUND

Progesterone is thought to mediate immune modulator effects by regulating uterine responsiveness. The aim of the study was to clarify the effect of transferrin and glycodelin A (former name PP14) as sialyl Lewis X-expressing glycoproteins on the release of progesterone by trophoblast cells in vitro.

METHODS

Cytotrophoblast cells were prepared from human term placentas by standard dispersion of villous tissue followed by a Percoll gradient centrifugation step. Trophoblasts were incubated with varying concentrations (50-300 microg/ml) of human amniotic fluid- and serum-transferrin as well as with glycodelin A. Culture supernatants were assayed for progesterone, human chorionic gonadotropin (hCG) and cortisol by enzyme immunometric methods.

RESULTS

The release of progesterone is increased in amniotic fluid transferrin- and glycodelin A-treated trophoblast cell cultures compared to untreated trophoblast cells. There is no relation between transferrin and the hCG or cortisol production of trophoblast cells.

CONCLUSION

The results suggest that sialyl Lewis carbohydrate antigen-expressing amniotic fluid glycoproteins modulate the endocrine function of trophoblasts in culture by upregulating progesterone production.

Major histocompatibility antigen expression on the bovine placenta: its relationship to abnormal pregnancies and retained placenta

In viviparous animals, regulation of expression of major histocompatibility complex (MHC) class I antigens by the trophoblast cells, which constitute the outermost layer of the placenta, seems to be critical for maternal immunological acceptance of an allogeneic fetus. Cattle are unusual in this regard, since the bovine trophoblast cells, in specific regions of the uterine/placental interface, normally express MHC class I antigens during the third trimester of gestation. This expression appears to be biologically relevant as MHC class I compatibility between a cow and her fetus has been associated with an increased incidence of placental retention. We have found significant differences in lymphocyte populations, cytokine production, and trophoblast cell apoptosis in the placentomes of MHC-compatible and -incompatible pregnancies at parturition. This suggests that maternal immunological recognition of fetal MHC class I proteins triggers an immune/inflammatory response that contributes to placental separation at parturition in cattle. Early in pregnancy, a complete shutdown of MHC class I expression by trophoblast cells appears to be critical for normal placental development and fetal survival. In bovine somatic cell nuclear transfer (SCNT) pregnancies, there is an extremely high rate of fetal loss between days 30 and 90 of pregnancy. We have shown that in bovine SCNT pregnancies, between days 34 and 63 of gestation, there is both abnormal expression of MHC class I antigens by trophoblast cells and an abnormal accumulation of lymphocytes within the uterine stroma. Consequently, it is likely that activation of the maternal mucosal immune system, within the uterus at the same time when placentomes are being established, interferes with the process of placentome development and leads to immune-mediated abortion. Our data suggest that bovine MHC-compatible pregnancies provide a unique model for studying regulation of the uterine immune system, as well as immune-mediated placental rejection.

Effect of post-insemination supplementation with PRID on pregnancy in repeat-breeder Holstein cows

Embryonic mortality contributes to repeat-breeding in dairy cows; luteal insufficiency is a known cause of embryonic mortality. The objective of this study was to assess the efficacy of supplementation with exogenous progesterone for 14 days on pregnancy maintenance in inseminated repeat-breeder dairy cows. On Day 5 after insemination, treated cows ( n=143 ) received a modified PRID (i.e. without estradiol capsule), which was removed on Day 19. Control cows ( n=148 ) did not receive any treatment. Overall there was no effect of PRID supplementation on pregnancy rates. However, when the study population was stratified by parity and stage of lactation, PRID supplementation significantly improved pregnancy rate in first and second parity late lactation cows (risk ratio = 3.26; 95% CI 1.22, 8.69). Pregnancy rates did not differ between PRID-treated cows with ( n=81 ) and without vaginitis. Control cows tended ( P=0.077 ) to have a higher proportion of abortions than PRID-treated cows (7/50 versus 2/51, respectively). In conclusion, young late lactation repeat-breeder cows benefited from progesterone supplementation, in terms of maintaining pregnancy until traditional time of pregnancy diagnosis.

Immunology of term and preterm labor

During pregnancy there is an alteration in maternal immunity within the uterus where innate, proinflammatory immune responses are tightly regulated to prevent immunological rejection of the fetal allograft. Disruption of the delicate balance of cytokines by bacteria or other factors increases the production of proinflammatory cytokines at the maternal-fetal interface and activates the parturition mechanism prematurely. Despite years of searching, there is still no broadly effective strategy for preventing preterm labor and most therapies are directed at inhibiting myometrial contractions and improving neonatal outcome. Recent studies with progestins and interleukin-10 (IL-10), however, are showing promise in randomized clinical trials and animal studies. Furthermore, the identification of the Toll-like receptors as upstream mediators of inflammation may offer alternative therapeutic targets for preventing this common pregnancy complication.

Steroidal regulation of uterine resistance to bacterial infection in livestock

Postpartum uterine infections reduce reproductive efficiency and have significant animal welfare and economic consequences. Postpartum uterine infections are classified as nonspecific, but Arcanobacterium pyogenes and Escherichia coli are usually associated with them in cattle and sheep. Pyometra is the most common type of uterine infection in dairy cattle, and it is detected almost exclusively in cows with active corpora lutea. Luteal progesterone typically down-regulates uterine immune functions and prevents the uterus from resisting infections. Progesterone also can down-regulate uterine eicosanoid synthesis. This seems to be a critical event in the onset of uterine infections, because eicosanoids can up-regulate immune cell functions in vitro. In addition, exogenous prostaglandin F2 alpha stimulates uterine secretion of prostaglandin F2 alpha and enhances immune functions in vivo. Thus, one may hypothesize that eicosanoids can override the negative effects of progesterone and that the up-regulatory effects of exogenous prostaglandin F2 alpha allow the uterus to resolve an infection, regardless of progesterone concentrations. Based on the results of studies to test that hypothesis, cows, sheep, and pigs in various physiological statuses are resistant to intrauterine infusions of Arcanobacterium pyogenes and Escherichia coli, unless progesterone concentrations are increased. In sheep and pigs, exogenous prostaglandin F2 alpha stimulates uterine production of prostaglandin F2 alpha and allows the uterus to resolve Arcanobacterium pyogenes-Escherichia coli-induced infections, even when progesterone is maintained at luteal phase concentrations before and after treatment. Prostaglandin F2 alpha is a proinflammatory molecule that stimulates the production of various proinflammatory cytokines, and it may enhance uterine production of leukotriene B4. Proinflammatory cytokines and leukotriene B4 enhance phagocytosis and lymphocyte functions. Even though there are clear associations among prostaglandin F2 alpha, leukotriene B4, proinflammatory cytokines, phagocytosis, and lymphocyte functions, the mechanism of action of exogenous prostaglandin F2 alpha in overriding the down-regulatory effects of progesterone and resolving uterine infections has not been elucidated. Defining this mechanism should yield new prevention and treatment strategies for uterine infections that do not rely on antibiotic and antimicrobial compounds.

Influence of sex hormones on the periodontium

OBJECTIVES

Sex hormones have long been considered to play an influential role on periodontal tissues, bone turnover rate, wound healing and periodontal disease progression. The objectives of this review article are to (1) address the link between sex hormones and the periodontium, (2) analyse how these hormones influence the periodontium at different life times and (3) discuss the effects of hormone supplements/replacement on the periodontium.

MATERIALS AND METHODS

Two autonomous searches were performed in English language utilizing Medline, Premedline and Pubmed as the online databases. Publications up to 2002 were selected and further reviewed. In addition, a manual search was also performed including specific related journals and books.

RESULTS

It is certain that sexual hormones play a key role in periodontal disease progression and wound healing. More specifically, these effects seem to differentiate by gender as well as lifetime period. In addition, the influence of sex hormones can be minimized with good plaque control and with hormone replacement.

CONCLUSION

Despite profound research linking periodontal condition with sex hormones kinetics, more definitive molecular mechanisms and therapy still remain to be determined.

The effects of maternal nutrition and body condition on placental and foetal growth in the ewe

This study investigated the effects of maternal body condition and nutrition on placental and foetal growth in mid-gestation. Welsh Mountain ewes (n=24) of body condition 3.5 (high, H) and 2.0 (low, L) at mating, were fed either 100 per cent or 70 per cent of their daily maintenance requirements from day 22 of gestation, yielding four groups: H100 (n=5), H70 (n=6), L100 (n=7) and L70 (n=6). On day 65, placental and foetal parameters were measured. Whilst the placentome number tended to be lower in L than H ewes, the mean placentome weight was significantly greater in L100 than H100 animals. Nutritionally related changes in IGFBP expression within the placentome and intercotyledonary endometrium may explain these findings, with IGFBP-3 expression in the luminal epithelium and caruncular stroma of the placentome villi being inversely correlated to placentome number and the total placentome weight respectively. The foetal CRL was shorter and the ponderal index greater in L than H ewes. The foetal CRL was positively correlated to maternal IGF-I concentrations and the placentome number, although the foetal weight remained unaltered by treatment. This study therefore demonstrates that body condition and ration can alter foetal and placental growth, perhaps by modifying systemic parameters and uterine IGF expression.

The bovine placenta; a source and target of steroid hormones: observations during the second half of gestation

Apart from estrone-3-sulfate (E1S) the bovine placenta produces progesterone (P4), though the corpus luteum is the major source of P4 responsible for maintaining pregnancy. So far the biological function of placental steroids in cattle is largely unknown. However, since the local availability of free estrone (E1) in the placenta seems to be controlled by sulfatase and sulfotranferase, the hypothesis was developed that placental estrogens and P4 might act as local regulatory factors. To test for such a function placentomes from 150, 220, 240, 270 days (D) pregnant and parturient cows were screened immunohistochemically for progesterone and estrogen receptors (PR, ER). PR were found at all stages in the caruncle in stromal cells and capillary pericytes but only at parturition in arterial walls. Percentage of PR-positive caruncular stromal cells (CSC) increased (P<0.05) from 51.8+/-2.6% at D150 to 58.9+/-1.8% at parturition. ER were detected in CSC, caruncular epithelial (CE) cells and in caruncular capillary pericytes. Mean percentage of ER-positive CSC decreased from 39.0+/-5.9% in pregnant cows to 17.5+/-8.3% at parturition (P<0.05). In CE all cells exhibited positive signals with the exception of those immediately surrounding large primary chorionic villi. Proliferation was assessed immunohistochemically by determining the percentage of Ki67-antigen positive cells. Highest values (P<0.001) were obtained for CE (58.0-68.3%), followed by the trophoblast (23.3-25.4%), CSC (10.6-45.3%) and the stroma of the chorionic villi (2.9-10.5%). A transient depression of proliferation in CSC between D150-270 (P<0.05) paralleled local estrogen tissue concentrations. The results suggest that placental estrogens and P4 are important factors controlling caruncular growth, differentiation and function.

Lymphocytes and T lymphocyte subsets are regionally distributed in the female goat reproductive tract: influence of the stage of the oestrous cycle

The reproductive tract of the female is a part of the mucosal system which protects from pathogens invasion. We have analysed the presence and distribution of total lymphocytes, plasma cells (antibody secreting B cells) and T lymphocytes subsets in the reproductive tract of the female goat. The influence of the oestrous cycle on the densities of lymphocytes and plasma cells of the cervix and uterus horn was evaluated in sections prepared for conventional histology. Immunocytochemistry was used for the study of lymphocyte subsets by confocal microscopy and immunoperoxidase techniques. Present results show that the reproductive tract of the goat is a site rich in lymphocytes. These cells were found mingled with the epithelial cells of the endometrium and distributed throughout the stroma. Lymphocyte aggregates were observed in the stroma. Lymphocyte but not plasma cell number changed depending on the reproductive stage of the goats. The impact of the hormonal environment was different for the cervix and uterine horn. Immunocytochemistry studies evidenced the presence of cells displaying immunoreactivity for both CD 4+ and CD 8+ antibodies in the epithelial layer and stroma of the cervix and uterine horn. These cells were more numerous in the cervix and were also found infiltrating the luminal epithelia of endometrial glands. Overall, our results indicate that lymphocyte distribution is different in the cervix and the horn, and is influenced by the stage of the reproductive cycle. In summary, CD 4+ and CD 8+ T lymphocytes subsets could be found in the endometrium of both the cervix and uterine horn of the goat reproductive tract.

Peri-partum changes in the intraepithelial lymphocyte population of sheep interplacentomal endometrium

PROBLEM

Previous studies have shown that the proportion of gammadeltaTCR+ large granulated lymphocytes (LGLs) increased markedly during pregnancy and declined dramatically by 2 days after parturition in sheep interplacentomal uterine epithelium. In the present study, the distribution, dynamics and fate of these cells, just before, during and immediately after parturition are described.

METHODS OF STUDY

Interplacentomal tissues were collected at 140 days postcoitus (dpc), 148 dpc, during parturition, 1-2 hr postpartum, 1 day postpartum (dpp) and 3 dpp, and were studied using light and electron microscopy, and immuno histochemistry. Uterine washings were collected at 148 dpc and examined for the presence of LGLs. Semi-thin Araldite sections taken at different stages were used to quantify the intraepithelial LGLs, non-granulated lymphocytes (NGLs) and apoptotic cells, whereas frozen sections were used to quantify CD45R+, CD8+ and gammadeltaTCR+ intraepithelial lymphocytes (IELs).

RESULTS

A dramatic decline in the proportion of IELs in the luminal epithelium during parturition was observed, mainly because of the decline in CD45R+, CD8+ and gammadeltaTCR+ IELs. There was also a significant decline in the number of granules/ LGL at parturition. This was accompanied by the presence of apoptotic cells of which some were LGLs. The proportions of IELs, LGLs and apoptotic cells markedly increased at 3 dpp. LGLs were found both in uterine washings at 148 dpc and in the uterine lumen at 3 dpp. Apoptosis of glandular epithelial cells was also evident at parturition and markedly increased at 1 dpp.

CONCLUSIONS

Our results demonstrated that the dramatic decline in the proportion of gammadeltaTCR+ LGLs at parturition was because of de-granulation, apoptosis and migration of these cells into the uterine lumen.

Reproductive Immunosuppression and Diet

Pregnancy sickness, a suite of "symptoms" that frequently co-occur during pregnancy, may be an adaptation providing behavioral prophylaxis against infection. Maternal immunosupression, necessary for tolerance of the fetus, results in gestational vulnerability to pathogens. Throughout the period of maximal vulnerability, dietary behavior is significantly altered via changes in nausea susceptibility and olfaction and the development of marked aversions and cravings. Of food types, meat is both the most likely to carry pathogens and the principal target of gestational aversions and pregnancy taboos. Because meat was prominent in ancestral human diets but hygienic procedures that effectively eliminate the risk of meat-borne infection are recent, such pathogens likely constituted a source of selective pressure on pregnant females throughout human history. Both the relatively low protein and energy demands of the first trimester and the existense of nonmeat alternatives would have allowed for the evolution of time-limited gestational meat-avoidance mechanisms.Complementing these mechanisms, gestational cravings target substances that may influence immune functioning and affect the availability of iron in the gastro-intestinal tract, thereby limiting the proliferation of iron-dependent pathogens. Clinical and ethnographic findings are examined in light of these proposals, and directions for future research are outlined.

Medroxyprogesterone acetate enhances in vivo and in vitro antibody production

In the present study we examine the effects of medroxyprogesterone acetate (MPA) on the specific antibody secretion to T-dependent antigens. Our results show that the in vivo administration of MPA to mice, 7 or 90 days before immunization with sheep red blood cells (SRBC), significantly enhanced both, primary and secondary antibody responses, without affecting delayed-type hypersensitivity (DTH). These effects could be counteracted by the anti-progestin onapristone or ZK 98299 (ZK) suggesting that MPA interacted with progesterone (PRG) receptors to increase B-cell response. To better understand the mechanisms involved in MPA activity we carried out cultures of splenocytes, bone marrow cells or lymph node cells from immunized mice in the presence of MPA, and evaluated the amount of antibody release to supernatants. We found that low doses of MPA (10(-9) M and 10(-10) M) significantly enhanced the in vitro production of specific immunoglobulin G (IgG) antibodies, an effect that appears to involve the interaction of the progestin with PRG receptors, as judged by the inhibition of MPA effects with ZK (10(-8) M) or RU486 (10(-9) M). These receptors were detected by flow cytometry analysis in a proportion of T lymphocytes. Because MPA did not increase the number of immunoglobulin-secreting cells, our findings suggest that MPA enhanced the capacity of individual cells to produce specific immunoglobulin.

Monocyte chemotactic protein-1 and -2 messenger ribonucleic acids in the ovine uterus: regulation by pregnancy, progesterone, and interferon-tau

Endometrial leukocytes may play important roles during pregnancy. Because chemokines are regulators of immune cell activity and trafficking, this study determined if mRNAs for monocyte chemotactic proteins (MCP) were present in the ovine uterus and regulated by progesterone (P) and/or recombinant ovine interferon tau (roIFN-tau). Uteri of normal cycling and pregnant ewes (experiment 1) and uteri of ovariectomized ewes receiving intrauterine infusions of IFN-tau and/or i.m. injections of P (experiment 2) were used to detect MCP-1 and MCP-2 mRNA. In experiment 1, slot-blot hybridization analysis of endometrial total RNA revealed that MCP-1 and MCP-2 mRNA levels did not change during the estrous cycle but increased between Days 13 and 19 of pregnancy. Using in situ hybridization, MCP-1 and MCP-2 mRNA were localized to immune cells in the subepithelial compact stroma. Histomorphological studies and in situ hybridization for major basic protein (MBP) indicated that MCP-positive immune cells were eosinophils. In experiment 2, treatment with P and roIFN-tau increased (P < 0.05) the number of MCP-1- and MCP-2-expressing eosinophils in the endometrium compared to ewes treated with P alone. Injection of the P receptor antagonist (ZK 137,316) inhibited effects of P and/or roIFN-tau to recruit eosinophils expressing MCP-1 and MCP-2 mRNAs. Endometrial production of MCPs by eosinophils during early pregnancy may play a role(s) in central implantation and/or placentation in ewes that is crucial for successful establishment of pregnancy.

Local versus systemic control of numbers of endometrial T cells during pregnancy in sheep

Pregnancy in sheep is associated with changes in numbers of specific T-lymphocyte populations in the uterine endometrium. These changes probably contribute to evasion by the conceptus of maternal immunological rejection and indicate a possible role for T cells in placental growth, parturition and post-parturient uterine defence against infection. The purpose of the present experiment was to evaluate the relative importance of systemic signals (i.e. those present throughout the uterus or from the circulation, including conceptus hormones secreted into the maternal blood) versus locally acting conceptus signals for regulating changes in numbers of endometrial lymphocytes during pregnancy. The approach taken was to surgically confine pregnancy to one uterine horn and compare differences in lymphocyte numbers between the two uterine horns as well as between both horns of pregnant ewes with those of ovariectomized ewes. As compared with ovariectomized ewes, there was a decline in numbers of CD45R+ lymphocytes within glandular epithelium and an increase in gammadelta T-cell number within the luminal epithelium. These changes occurred in both the pregnant and non-pregnant uterine horns of unilaterally pregnant ewes. Moreover, there were no significant differences in lymphocyte numbers between the two uterine horns of unilaterally pregnant ewes. Expression of CD25 was absent in tissues from both uterine horns. In conclusion, changes in numbers of endometrial lymphocytes during pregnancy, rather than due to locally acting signals of conceptus origin, are the result of hormonal signals of maternal or conceptus origin that either act directly on endometrial lymphocytes or stimulate the uterine endometrium to induce synthesis of regulatory molecules that affect lymphocyte dynamics.