No evidence for apoptosis of decidual leucocytes in normal and molar pregnancy: implications for immune privilege

Immune cells in normal pregnancy and gestational trophoblastic diseases

A healthy pregnancy requires the development of maternal-fetal immune tolerance against the semi-allogeneic fetus. The interactions between the trophoblastic cells and the maternal immune cells (p.e., natural killer cells, T cells, macrophages, dendritic cells and B-cells) are important for the development of the maternal-fetal immune tolerance and the placental growth and function. These interactions are mediated by cell to cell contact and secreted molecules such as cytokines, chemokines, angiogenic factors and growth factors. The maternal immune cells are present in normal non-pregnant and pregnant endometrium and there are several lines of evidence based on immunohistochemical and RNA sequencing data that the decidual immune cells and immune-related pathways display alterations in GTD, which may have pathogenetic and clinical significance. The present review focuses on the usefulness of the immunohistochemical analysis which provides multiparametric in situ information regarding the numbers, the immunophenotypes and the immunotopographical distributions of the decidual immune cells in tissue sections from normal pregnancy and GTD. We also discuss the significance of the immunohistochemical information in order to gain insight in the putative mechanisms explaining the alterations of the decidual immune cells in GTD and the potential implications of these alterations in the pathogenesis and the clinical behavior of GTD.

Apoptosis and Bcl-2 protein expression in human placenta over the course of normal pregnancy

Apoptosis plays a central role in organ development, homeostasis and immune defence in multicellular organisms and is strictly controlled in part by members of Bcl-2 family. The Bcl-2 is a pro-survival molecule identified through its involvement in B-cell lymphomas. The aim of the study was to evaluate the incidence of apoptosis in the human placenta at different stages of pregnancy and to correlate it further with Bcl-2 expression. A total of 96 placental samples from first trimester, mid-trimester and uncomplicated term pregnancies were collected (n = 32 + 32 + 32). M30 cyto death monoclonal antibody was used to identify apoptotic cells. The apoptosis index of first trimester placentae was 2.33 ± 1.70, mid- trimester was 1.77 ± 1.36 and term placenta was 1.15 ± 0.21. Bcl-2 protein was found immunolocalized in the cytoplasm of syncytiotrophoblast. Apoptosis index was significantly reduced in term cases as compared with first trimester (P < 0.002) and mid-trimester placentae (P = 0.01). On the contrary, Bcl-2 expression was significantly higher at term cases than in first trimester (P < 0.0001) and mid-trimester cases (P < 0.001). The present study divulges the importance of apoptosis in permitting normal physiological turnover of villous trophoblast and also exhibits the contribution of bcl-2 in maintaining syncytial integrity throughout normal pregnancy.

Analysis of RCAS1 immunoreactivity within hydatidiform mole cells and decidual cells according to the applied therapeutic strategy: surgery or surgery followed by chemotherapy

INTRODUCTION

Trophoblast cells cooperate with both maternal immune cells and decidual cells to help develop the suppressive microenvironment of the endometrium. The maternal immune response against hydatidiform mole depends on this suppressive endometrial profile. Since RCAS1 is one of the molecular factors participating in the development of the suppressive profile of the endometrium we decided to examine the immunoreactivity of the RCAS1 within both the trophoblast and decidual cells during the development of hydatidiform mole.

METHODS

We analyzed the immunoreactivity of RCAS1 on both trophoblast and decidual cells derived from patients who underwent curettage because of hydatidiform mole. These patients were then divided into two subgroups according to whether or not they required chemotherapy after the surgical procedure.

RESULT

We observed significantly lower immunoreactivity levels of both RCAS1 within the complete molar lesions of the patients on whom surgery alone was performed when compared to the levels found in those for whom surgery was followed by chemotherapy.

CONCLUSION

RCAS1 staining may provide information regarding the intensity of the immunosuppressive microenvironment of both the molar lesion and the endometrium. This information can prove significant in determining the clinical course of hydatidiform mole.

Enhanced Hsp70 expression protects against acute lung injury by modulating apoptotic pathways

The Acute respiratory distress syndrome (ARDS) is a highly lethal inflammatory lung disorder. Apoptosis plays a key role in its pathogenesis. We showed that an adenovirus expressing the 70 kDa heat shock protein Hsp70 (AdHSP) protected against sepsis-induced lung injury. In this study we tested the hypothesis that AdHSP attenuates apoptosis in sepsis-induced lung injury.

Sepsis was induced in rats via cecal ligation and double puncture (2CLP). At the time of 2CLP PBS, AdHSP or AdGFP (an adenoviral vector expressing green fluorescent protein) were injected into the tracheas of septic rats. 48 hours later, lungs were isolated. One lung was fixed for TUNEL staining and immunohistochemistry. The other was homogenized to isolate cytosolic and nuclear protein. Immunoblotting, gel filtration and co-immunoprecipitation were performed in these extracts. In separate experiments MLE-12 cells were incubated with medium, AdHSP or AdGFP. Cells were stimulated with TNFα. Cytosolic and nuclear proteins were isolated. These were subjected to immunoblotting, co- immunoprecipitation and a caspase-3 activity assay.

TUNEL assay demonstrated that AdHSP reduced alveolar cell apoptosis. This was confirmed by immunohistochemical detection of caspase 3 abundance. In lung isolated from septic animals, immunoblotting, co-immunoprecipitation and gel filtration studies revealed an increase in cytoplasmic complexes containing caspases 3, 8 and 9. AdHSP disrupted these complexes.

We propose that Hsp70 impairs apoptotic cellular pathways via interactions with caspases. Disruption of large complexes resulted in stabilization of lower molecular weight complexes, thereby, reducing nuclear caspase-3. Prevention of apoptosis in lung injury may preserve alveolar cells and aid in recovery.

Lysophosphatidic acid up-regulates expression of growth-regulated oncogene-alpha, interleukin-8, and monocyte chemoattractant protein-1 in human first-trimester trophoblasts: possible roles in angiogenesis and immune regulation

The serum lysophospholipase D activity and production of lysophosphatidic acid (LPA) increase in women with pregnancy. The effects of LPA on human placenta tissue remained unclear. We investigate the expression of LPA receptors and function of LPA in human first-trimester trophoblasts. Normal villous trophoblasts were obtained from termination of first-trimester gestation. We examined the expression of LPA receptors in primary culture of trophoblasts and the tissue. The effects of LPA on the expressions of chemokines of trophoblasts were examined using RT-PCR and enzyme immunoassay. We delineate signal pathways of LPA-inducing relevant chemokines in trophoblasts. The secretory chemokines were tested for angiogenic function using human endometrial microvascular endothelial cells and for immunological chemotaxis using decidual natural killer cells and THP-1 monocytes. The results revealed the expression of LPA1 receptors in trophoblast cells. LPA enhanced growth-regulated oncogene (GRO)-alpha, IL-8 and monocyte chemoattractant protein (MCP)-1 expressions in a time- and dose-dependent manner. Mechanistic dissection disclosed that LPA functioned mainly via the LPA1 receptor, Gi protein, various signal mediators of ERK, protein kinase C, p38, Akt, and c-Jun N-terminal kinase, and nuclear factor-kappaB pathways to secrete these chemokines. LPA-induced IL-8 protein secretion of trophoblasts enhanced permeability, migration, proliferation, and capillary tube formation of human endometrial microvascular endothelial cells. LPA-induced GRO-alpha and MCP-1 incited chemotaxis of natural killer cells and monocytes. We demonstrate that LPA mediates trophoblast cells to produce GRO-alpha, IL-8, and MCP-1 via LPA1 receptors and nuclear factor-kappaB-dependent signal pathways. Through LPA-induced chemokine production, human first-trimester trophoblast cells may regulate angiogenesis and innate immune system in early pregnancy.

Antigen-presenting cells and materno-fetal tolerance: an emerging role for dendritic cells

During pregnancy, a delicate balance of innate and adaptive immune responses at the maternal-fetal interface promotes survival of the semi-allogeneic embryo and, at the same time, allows effective immunity to protect the mother from environmental pathogens. As in other tissues, antigen handling and processing in the decidualized endometrium constitutes a primary event in the onset of immune responses and is therefore likely to determine their stimulatory or tolerogenic nature. Maternal antigen-presenting cells [macrophages and dendritic cells (DCs)] are scattered throughout the decidualized endometrium during all stages of pregnancy and appear to be important players in this feto-maternal immune adjustment. This review focuses on the characterization of decidual macrophages and DCs, as well as their involvement in cell-cell interactions within the decidual leukocyte network, which are likely to influence uterine and placental homeostasis as well as the local maternal immune responses to the fetus during pregnancy.

Human uterine natural killer cells: a reappraisal

The presence of granulated cells within the uterus of many species has been recognised for many years but only recently have these been recognised to be a type of NK cell. Various terms have been applied to the cells, including endometrial granulocyte, K cell and, in mouse and rat, granulated metrial gland cell. Although early studies are often based on histology and electron microscopy, these often include important information for current studies. In vitro studies of purified cells have focused particularly on cytotoxicity and cytokine production and roles in the control of trophoblast invasion and spiral artery remodelling in human pregnancy have been proposed. Evidence in mouse has implicated uNK cell production of IFN-gamma in vascular remodelling but evidence for such a role for human uNK cells remains to be established. Investigation of uNK cells in human pregnancy is hampered by the lack of availability of tissues from the first half of the second trimester of pregnancy when vascular remodelling occurs and also by possible differences between cells from different regions of decidua. The presence of similar cells in species with no trophoblast invasion into the uterus and epitheliochorial placentation raises the question of whether control of trophoblast invasion by human uNK cells is important in vivo and raises the possibility of another function which is conserved between species.