Effect of IFN-gamma and IFN-alpha on killing of human trophoblast by decidual LAK cells

Necrotic Enteritis in Broiler Chickens: A Review on the Pathogen, Pathogenesis, and Prevention

Clostridium perfringens type A and C are the primary etiological agents associated with necrotic enteritis (NE) in poultry. The predisposing factors implicated in the incidence of NE changes the physical properties of the gut, immunological status of birds, and disrupt the gut microbial homeostasis, causing an over-proliferation of C. perfringens. The principal virulence factors contributing to the pathogenesis of NE are the α-toxin, β-toxin, and NetB toxin. The immune response to NE in poultry is mediated by the Th1 pathway or cytotoxic T-lymphocytes. C. perfringens type A and C are also pathogenic in humans, and hence are of public health significance. C. perfringens intoxications are the third most common bacterial foodborne disease after Salmonella and Campylobacter. The restrictions on the use of antibiotics led to an increased incidence of NE in poultry. Hence, it is essential to develop alternative strategies to keep the prevalence of NE under check. The control strategies rely principally on the positive modulation of host immune response, nutritional manipulation, and pathogen reduction. Current knowledge on the etiology, pathogenesis, predisposing factors, immune response, effect on the gut microbial homeostasis, and preventative strategies of NE in this post-antibiotic era is addressed in this review.

Changing the paradigm of IFN-γ at the interface between innate and adaptive immunity: Macrophage-derived IFN-γ

IFN-γ plays a critical role in the immune response to bacterial infections. It is established that IFN-γ is mainly produced by NK/ILC1 cells and T cells, and most of papers have rejected the biologic reality of alternative sources for more than 20 years. Here, we are proposing to revisit this dogma and discuss the role of macrophage-derived IFN-γ in bacterial infections. Our hypothesis is based on a panel of publications and is recently revived by our results on placenta, a chimeric organ in which the immune response is tailored to protect the fetus from mother's immune response. The culture of purified placental macrophages is associated with a production of IFN-γ that may contribute to fetal protection from bacterial infections before eliciting a Th1-like immune response potentially pathogenic for pregnancy. Hence, macrophage IFN-γ may be a novel actor of early crosstalk between innate and adaptive immunity in the context of host defense against bacterial infections.

Intercellular wireless communication network between mother and fetus in rat pregnancy-a study on directed and weighted network

BACKGROUND

The maternal body forms a wireless communication system with the embryo through the blood circulation system. Obviously, direct sampling from early embryos is damaging. Therefore, we detected changes in the concentrations of 30 signaling molecules in serum from the pregnant rats at the 14 time points, then the intercellular wireless communication network was established, to explore the regularity of signal communication between mother and fetus.

METHOD OF STUDY

We used liquid chip scanning technology to detect 30 signal molecules at 14 time points. Statistical analysis of the data yielded significant change signal molecules. According to the secretory cells and effector cells involved in signal molecules, the communication network of different stages were drawn by using Biograph software.

RESULTS

The process could be divided into 4 periods including early, middle, late pregnancy, and postpartum. In early pregnancy, two immune transformations occur: (a) interleukin-10 (IL-10), interleukin-13 (IL-13) increased at day 5, which promoted immunoglobin G (IgG) secretion, provided protection through the neonatal Fc receptor for IgG (FcγRn) crossing the placental barrier to reach the embryo, achieved T helper 1 (Th1) transformation into T helper 2 (Th2), reduced maternal innate and cellular immunity, and prevented fetal abortion; (b) the fetal heart was fully developed at day 7, with circulatory system established, which provided a platform for intercellular information exchange. The second transformation corresponded to the maternal immune system providing signaling molecules for the embryo to promote Th2 transformation into Th1, thus activating embryonic innate immune cells, and enabling antibody-mediated immune recognition, response and protection. Days 9-19 was a stable period. After 21 days of pregnancy, the maternal body prepared for delivery. The characteristic signaling molecules in the process were monocyte chemotactic protein-1 (MCP-1), IL-10, IL-13, IL-1ɑ, interferon-inducible protein-10 (IP-10), regulated upon activation normal T cell expressed and secreted (RANTES), thyroid stimulating hormone (TSH), IL-2, IL-6, IL-12p70 and IL-18.

CONCLUSION

Detection of concentration changes of the factors in maternal serum could provide a tool for monitoring, diagnosis, prediction and treatment of embryo differentiation, development and health.

Effect of yeast-derived products and distillers dried grains with solubles (DDGS) on growth performance and local innate immune response of broiler chickens challenged with Clostridium perfringens

This study evaluated the effect of yeast-derived products on growth performance, gut lesion score, intestinal population of Clostridium perfringens, and local innate immunity of broiler chickens challenged with C. perfringens. One-day-old broiler chickens were randomly assigned to eight dietary treatments providing six replicate pens of 55 birds each per treatment. Dietary treatments consisted of Control diets without and with C. perfringens challenge, and diets containing bacitracin methylene disalicylate (BMD, 55 g/tonne), nucleotides (150 g/tonne), yeast cell wall (YCW, 300 g/tonne), and a commercial product Maxi-Gen Plus (1 kg/tonne) fed to chickens challenged with C. perfringens. Diets containing 10% distillers dried grains with solubles without and with C. perfringens challenge were also used. Birds were orally challenged with C. perfringens (10(8) colony-forming units (cfu)/bird) on day 14. On day 21, intestinal samples were collected for gene expression analysis. Pathogen challenge significantly (P < 0.05) impaired feed intake, body weight gain, and feed conversion ratio (FCR) shortly after the challenge (14-21 days). Increased C. perfringens counts and intestinal lesion scores were observed for challenged birds except the BMD-containing diet. Over the entire trial (1-35 days), no difference in growth performance was observed except the BMD diet which improved FCR over the Control, challenged group. Birds receiving nucleotides showed increased expression of toll-like receptors and cytokines interleukin (IL)-4 and IL-18 compared to the Control, challenged group. Expression of macrophage mannose receptor and IL-18 was upregulated in birds receiving YCW. Increased expression of cytokines and receptors involved in innate immunity in broilers receiving nucleotides and YCW suggests the immunomodulatory properties of these products under pathogen challenge conditions.

Trophoblast invasion

The establishment of a pregnancy depends upon mechanisms of forming close contacts between embryonic/fetal and maternal tissues. The starting point is the attachment of the blastocyst to the uterine wall, and this critical step is followed by a series of different morphogenetic events leading to placentation. These processes depend on the invasive properties of extra-embryonic trophectoderm-derived cells that show their highest expression in species with haemochorial placentation, i.e. Insectivores, rodents, and primates including the human. In this review we will concentrate upon the human with occasional reference to other species.

Promotion of angiogenesis by human endometrial lymphocytes

The human endometrium is a unique tissue that undergoes dramatic monthly remodeling during the menstrual cycle in preparation for an implanting conceptus. This remodeling involves sequential proliferation and differentiation of endometrial stromal and epithelial cells, coupled with extensive angiogenesis and infiltration of a specific specialized immune cell subset. Increasing evidence points to an essential role for these maternal leukocytes in stimulating the endometrial angiogenesis, and we propose that they also play a key role in the decidual vascular transformation. Aberrant endometrial angiogenesis, decidualisation and vascular transformation is thought to underlie many pathologies of pregnancy, from infertility to the development of preeclampsia and Intra Uterine Growth Restriction. In this chapter we review the cellular processes associated with each stage of endometrial and decidual transformation, detailing the role of the immune cell populations and the angiogenic and chemotactic factors secreted by them.

Natural killer cells in pregnancy and recurrent pregnancy loss: endocrine and immunologic perspectives

The endocrine system and the immune system interact closely during implantation and maintenance of pregnancy. One of the most striking examples of this communication is at the level of the decidua (endometrium of pregnancy). Here, under the influence of sex steroids, there is a dramatic increase of a unique population of lymphocytes, the uterine natural killer (uNK) cells, in early pregnancy. These cells derive predominantly from a subset of peripheral blood NK cells, which under hormonal influence gets recruited to the uterus. In mice, uNK cells play an important role in the development of placental vasculature. The role of these cells in human pregnancy is still not definitively established; however, they are believed to promote placental and trophoblast growth and provide immunomodulation at the maternal-fetal interface. In contrast to their presumptive role in the maintenance of a healthy pregnancy, uNK cells and peripheral NK cells are dysregulated in unexplained recurrent pregnancy loss. Herein, we review NK cell populations, their changes in number and function in altered endocrine environments during the menstrual cycle and pregnancy, the current data on their potential role in unexplained recurrent pregnancy loss, and mechanisms for potential therapies targeted to NK cell function for this enigmatic disorder.

The myometrial junctional zone spiral arteries in normal and abnormal pregnancies: a review of the literature

Deep placentation in the human requires physiologic transformation of the spiral arteries into uteroplacental vessels. This process involves the inner myometrial segment (junctional zone) of the spiral arteries and is effected by trophoblast invasion of the vessel wall, resulting in complete loss of the arterial structure and deposition of fibrinoid and fibrous tissues. Absent or inadequate physiologic changes in the junctional zone spiral arteries limits placental blood flow in pregnancies complicated by preeclampsia and fetal growth restriction. The cause of defective deep placentation is still unknown, although it is often attributed to impaired trophoblast function and migration. However, trophoblast invasion is preceded by decidual remodeling of maternal tissues, a process that is initiated in the endometrium but extends into the junctional zone. This review examines the mechanisms that control decidualization and subsequent trophoblast invasion in normal and abnormal pregnancies. The possibility that disruption of the decidual process in the secretory phase of the menstrual cycle triggers a cascade of events resulting in failed deep placentation is explored.

Granulated decidual cells in the mouse deciduoma: a putative source of decidual prolactin in mice

Decidual cells are endometrial fibroblasts that redifferentiate during pregnancy in several species of mammals. In this work, we describe a subpopulation of resident decidual cells in the mouse endometrium that are joined by intercellular junctions and have cytoplasmic granules. Decidualization was induced in pseudopregnant mice on the 4th day of pseudopregnancy by injection of 30 microl of arachis oil into the uterine lumen. The uteri were collected on day 8 of pseudopregnancy (at 4 p.m., 8 p.m. and 11 p.m.) and on day 9 (at 8 a.m.). The tissues were fixed for light and electron microscopy. During day 8 of pseudopregnancy, granulated cells were present at the antimesometrial pole of the endometrium; they were concentrated at the periphery of the antimesometrial decidua and disappeared on day 9 of pseudopregnancy. The cytoplasm of the granulated decidual cells had acidophilic granules that stained also with periodic acid-Schiff (PAS). These granules stained with anti-rat prolactin antibody in both light and electron microscope immunocytochemical preparations. Vacuoles of various sizes were always present in the granulated cells. A PAS-positive and prolactin-stained material was often deposited at the periphery of the vacuoles. Our results indicate that the granulated decidual cells are the source of decidual prolactin which accumulates in cytoplasmic granules. These granulated cells therefore form a transient gland in the mouse antimesometrial endometrium (granulated decidual gland).

Endometrial CD56+ natural killer cells in women with recurrent miscarriage: a histomorphometric study

Endometrial natural killer (NK) cells were compared in luteal-phase endometrial samples from women with recurrent miscarriage and from normal subjects. Cryostat sections were labelled using a monoclonal antibody to CD56 using an avidin-biotin complex method and a morphometric study performed. Increased mean numbers of CD56+ cells were documented in the endometrium of women with recurrent early miscarriage only. These findings suggest a possible role for NK cells in the pathogenesis of recurrent early pregnancy loss.

Increased blood vessel density in decidua parietalis is associated with spontaneous human first trimester abortion

Spontaneous pregnancy loss affects 15-18% of couples, and a number of potential causes are being discussed. The purpose of the present study was to assess if angiogenic disorders in the decidua of early human pregnancy could be related to spontaneous abortions. First trimester human decidua from elective terminations of normally progressing pregnancies and from missed abortions were investigated immunohistochemically. We quantified vessel density in decidua from normal pregnancies and from abortions by von Willebrand factor (vWF), platelet endothelial cell adhesion molecule (PECAM-1) and CD34 staining. Decidual blood vessel expression of alphavbeta3 integrin was also investigated. Significant increase (P < 0.02) in vessel density was observed in decidua parietalis of abortions, compared to decidua basalis. This increase was detected on slides stained for vWF and CD34, but not for PECAM-1. We observed a 15% increase analysing with vWF and a 77% increase with CD34 staining. alphavbeta3 integrin expression was not significantly different, neither in decidua parietalis from abortion, nor parietalis from normal pregnancies. Our data suggest that the increased vascularization in decidua parietalis from abortions could reflect complex disorders, such as specific cytokine expressions and hypoxia phenomena during the development of the decidua.

Trophoblast Cell Line Resistance to NK Lysis Mainly Involves an HLA Class I-Independent Mechanism

The lack of classical HLA molecules on trophoblast prevents allorecognition by maternal T lymphocytes, but poses the problem of susceptibility to NK lysis. Expression of the nonclassical class I molecule, HLA-G, on cytotrophoblast may provide the protective effect. However, the class I-negative syncytiotrophoblast escapes NK lysis by maternal PBL. In addition, while HLA-G-expressing transfectants of LCL.721.221 cells are protected from lymphokine-activated killer lysis, extravillous cytotrophoblast cells and HLA-G-expressing choriocarcinoma cells (CC) are not. The aim of this work was therefore to clarify the role of HLA class I expression on trophoblast cell resistance to NK lysis and on their susceptibility to lymphokine-activated killer lysis. Our results showed that both JAR (HLA class I-negative) and JEG-3 (HLA-G- and HLA-Cw4-positive) cells were resistant to NK lysis by PBL and were equally lysed by IL-2-stimulated PBL isolated from a given donor. In agreement, down-regulating HLA class I expression on JEG-3 cells by acid treatment, masking these molecules or the putative HLA-G (or HLA-E) receptor CD94/NKG2 and the CD158a/p58.1 NKR with mAbs, and inducing self class I molecule expression on JAR cells did not affect NK or LAK lysis of CC. These results demonstrate that the resistance of CC to NK lysis mainly involves an HLA class I-independent mechanism(s). In addition, we show that the expression of a classical class I target molecule (HLA-B7) on JAR cells is insufficient to induce lysis by allospecific polyclonal CTL.

Functions of human decidual NK cells

The main population of lymphocytes found in the human decidua during early pregnancy are NK-like cells with a distinctive phenotype, CD56bright CD16- CD3-. These cells are in close association with invading trophoblast that may be their in vivo target. We have examined three aspects of decidual NK function in vitro: cytotoxicity, proliferation, and cytokine production. The functional assays indicate uterine lymphocytes differ fundamentally from both PBL and even from classical circulating NK cells. Their role in the establishment of normal pregnancy remains unknown.

Presence of activated macrophages in a murine model of early embryo loss

PROBLEM

Even though our knowledge of the phenomenon at play at the fetoplacental interface has greatly advanced during the past years, a complete understanding of the reasons why the developing embryo is not rejected by maternal immune effector cells remains largely unknown.

METHODS

We have used immunohistochemistry with the macrophage-specific markers F4/80 and MHC II to study the relationship between decidual infiltration and resorption in murine models of embryo loss between days 6 and 10 of gestation.

RESULTS

Analysis of day 8 CBA/J x DBA/2 pregnancies has revealed 2 distinct populations of embryos. The majority (69.4%) expressed low levels of F4/80+ cells, but a minority (30.6%) expressed much higher level of the macrophage marker. In FBA/J x BALB/c, most embryos (91.7%) expressed low numbers of F4/80+ cells. As earlier experiments established that products of activated macrophages (TNF-alpha and nitric oxide) were implicated in embryo loss in this model, the activation status of the F4/80+ macrophages was assessed through the cell surface expression of MHC II. Again, a similar association was established: 30.6% of the CBA/J x DBA/2 embryos were infiltrated by significantly more MHC II+ cells than the control CBA/J x BALB/c mating. Finally, when coordinate expression of F4/80, MHC II and CD11b was assessed, it was found that an embryo significantly infiltrated by cells bearing one of the 3 markers was also heavily infiltrated by cells bearing the 2 other markers.

CONCLUSIONS

This study has shown that the augmented infiltration of the deciduum with maternal macrophages is an early event which precedes spontaneous abortion of the early embryo.

The equine endometrial cup reaction: a review

The function of eCG in equine pregnancy is far from clear but it has become evident that eCG has little or no FSH activity in the horse and is therefore probably not responsible for the secondary ovulations. eCG does have luteotrophic activity and it could play a role in the resurgence of the primary corpus luteum (1,7,44). Some evidence exists that the receptor population on the equine gonads is heterogenous in a way that makes it possible to distinguish eCG from eLH, resulting in different post-receptor effects (7). There is also evidence that eCG itself is heterogenous, both in glycosylation and in primary structure, not only between different individual animals but also within one animal during different stages of gestation. The differences could simply reflect the difference between stored and secreted hormone, but on the other hand the release of different eCG forms could be under endocrine control, allowing the mare to produce forms appropriate to specific biological needs (74). Thus some forms of eCG could play a role in immunological events taking place at the foeto-maternal interface. The role of cytotoxic antibodies in the equine pregnancy is not understood. The fact that they are not harmful to the pregnancy can be explained by the fact that their target, the paternal MHC molecules, are withdrawn from the endometrial cup tissue by the time the antibodies start appearing in the circulation. This unique way of regulation of MHC expression is also poorly understood.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of decidual lymphocytes from chorionic villus samples: phenotypic analysis and growth in vitro

PROBLEM

Giemsa stained cell isolates prepared from chorionic villus samples (CVS) contain granulated cells morphologically similar to large granular lymphocytes.

METHOD

Phenotypic characterization of these cellular isolates by two-color immunofluorescence and subsequent in vitro culture in the presence of recombinant interleukin-2 (rIL-2) were done in order to determine whether CVS could serve as a source of decidual lymphocytes.

RESULTS

A major fraction of the CVS-derived lymphocytes were characterized as decidual NK cells, exhibiting high levels of CD56 expression (CD56+bright), without concomitant expression of CD16. The T cell population present in CVS-derived lymphocytes contained both CD4+ and CD8+ cells in a ratio somewhat reduced compared to that found in peripheral blood. While both T cells and CD56+bright cells from CVS proliferate in vitro in response to rIL-2 alone, preferential growth of CD56+bright cells was accomplished using a selective culture technique wherein co-culture with an irradiated, B lymphoblastoid cell line promoted the growth of CD56+ cells.

CONCLUSION

CVS contains decidual NK cells and T cells that proliferate in response to rIL-2 and/or third party stimulator cells. These culture techniques will allow investigations into the maturation and/or activation of decidual NK cells and T cells.

In vitro cytotoxic activity of cord blood NK cells against herpes simplex virus type-1 infected purified human term villous cytotrophoblast

Transplacental infection of the fetus with herpes simplex virus (HSV) is associated with high morbidity. The present study was undertaken to shed light on the possible participation of the fetal immune system in the elimination of HSV from placental unit. In a chromium release assay cultured term villous trophoblast cells, regardless of infection with HSV-1, were found resistant to lysis by cord blood natural killer (CBNK) cells. In contrast to this, CBNK cells exhibited a basal level of cytotoxic activity against placental fibroblasts, which was significantly increased by preceding infection of the target cells with HSV-1. Stimulation of CBNK cells with interferon-beta purified from trophoblast (tro-IFN-beta) increased the killing of both HSV-1 infected and uninfected fibroblast, while HSV-1-infected and uninfected term villous trophoblast cells remained resistant to lysis. IL-2-stimulated CBNK cells were able to lyse villous trophoblast cells at a low level, but no significant difference in the susceptibility of the HSV-1-infected and uninfected trophoblast cell was detected.

In situ hybridization and northern blot demonstration of HLA-G mRNA in human trophoblast populations by locus-specific oligonucleotide

Trophoblast cells from normal first trimester pregnancies have been shown to express the nonclassical class I molecule, HLA-G, which is nonpolymorphic and has a heavy chain of 40 kD. In this study, in situ hybridization experiments were performed using a biotinylated HLA-G specific oligonucleotide on sections of normal placenta including the implantation site. HLA-G mRNA was identified in all extravillous trophoblast populations including the cytotrophoblast cell columns, interstitial trophoblast, endovascular trophoblast, and placental bed giant cells. In addition, villous cytotrophoblast and villous mesenchymal cells also contained HLA-G transcripts, but villous syncytiotrophoblast was always negative.