Interaction between HLA-G and monocyte/macrophages in human pregnancy

Using bioinformatics and systems biology methods to identify the mechanism of interaction between COVID-19 and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is considered a risk factor for severe COVID-19, but the mechanism remains unknown. This study used bioinformatics to help define the relationship between these diseases. The GSE147507 (COVID-19), GSE126848 (NAFLD), and GSE63067 (NAFLD-2) datasets were screened using the Gene Expression Omnibus. Common differentially expressed genes were then identified using a Venn diagram. Gene ontology analysis and KEGG pathway enrichment were performed on the differentially expressed genes. A protein-protein interaction network was also constructed using the STRING platform, and key genes were identified using the Cytoscape plugin. GES63067 was selected for validation of the results. Analysis of ferroptosis gene expression during the development of the 2 diseases and prediction of their upstream miRNAs and lncRNAs. In addition, transcription factors (TFs) and miRNAs related to key genes were identified. Effective drugs that act on target genes were found in the DSigDB. The GSE147507 and GSE126848 datasets were crossed to obtain 28 co-regulated genes, 22 gene ontology terms, 3 KEGG pathways, and 10 key genes. NAFLD may affect COVID-19 progression through immune function and inflammatory signaling pathways. CYBB was predicted to be a differential ferroptosis gene associated with 2 diseases, and the CYBB-hsa-miR-196a/b-5p-TUG1 regulatory axis was identified. TF-gene interactions and TF-miRNA coregulatory network were constructed successfully. A total of 10 drugs, (such as Eckol, sulfinpyrazone, and phenylbutazone) were considered as target drugs for Patients with COVID-19 and NAFLD. This study identified key gene and defined molecular mechanisms associated with the progression of COVID-19 and NAFLD. COVID-19 and NAFLD progression may regulate ferroptosis through the CYBB-hsa-miR-196a/b-5p-TUG1 axis. This study provides additional drug options for the treatment of COVID-19 combined with NAFLD disease.

The Mac Is Back: The Role of Macrophages in Human Healthy and Complicated Pregnancies

Pregnancy is a fascinating immunological paradox: the semi-allogeneic fetus generally grows without any complications. In the placenta, fetal trophoblast cells come into contact with maternal immune cells. Inaccurate or inadequate adaptations of the maternal immune system could lead to problems with the functioning of the placenta. Macrophages are important for tissue homeostasis, cleanup, and the repair of damaged tissues. This is crucial for a rapidly developing organ such as the placenta. The consensus on macrophages at the maternal-fetal interface in pregnancy is that a major proportion have an anti-inflammatory, M2-like phenotype, that expresses scavenger receptors and is involved in tissue remodeling and the dampening of the immune reactions. Recent multidimensional analyses have contributed to a more detailed outlook on macrophages. The new view is that this lineage represents a highly diverse phenotype and is more prevalent than previously thought. Spatial-temporal in situ analyses during gestation have identified unique interactions of macrophages both with trophoblasts and with T cells at different trimesters of pregnancy. Here, we elaborate on the role of macrophages during early human pregnancy and at later gestation. Their possible effect is reviewed in the context of HLA incompatibility between mother and fetus, first in naturally conceived pregnancies, but foremost in pregnancies after oocyte donation. The potential functional consequences of macrophages for pregnancy-related immune reactions and the outcome in patients with recurrent pregnancy loss are also discussed.

Leukocyte immunoglobulin-like receptor subfamily B: A novel immune checkpoint molecule at the maternal-fetal interface

Due to their crucial roles in embryo implantation, maternal-fetal tolerance induction, and pregnancy progression, immune checkpoint molecules (ICMs), such as programmed cell death-1, cytotoxic T-lymphocyte antigen 4, and T cell immunoglobulin mucin 3, are considered potential targets for clinical intervention in pregnancy complications. Despite the considerable progress on these molecules, our understanding of ICMs at the maternal-fetal interface is still limited. Identification of alternative and novel ICMs and the combination of multiple ICMs is urgently needed for deeply understanding the mechanism of maternal-fetal tolerance and to discover the causes of pregnancy complications. Leukocyte immunoglobulin-like receptor subfamily B (LILRB) is a novel class of ICMs with strong negative regulatory effects on the immune response. Recent studies have revealed that LILRB is enriched in decidual immune cells and stromal cells at the maternal-fetal interface, which can modulate the biological behavior of immune cells and promote immune tolerance. In this review, we introduce the structural features, expression profiles, ligands, and orthologs of LILRB. In addition, the potential mechanisms and functions mediated by LILRB for sustaining the maternal-fetal tolerance microenvironment, remodeling the uterine spiral artery, and induction of pregnancy immune memory are summarized. We have also provided new suggestions for further understanding the roles of LILRB and potential therapeutic strategies for pregnancy-related diseases.

Cytochrome P450 26A1 Modulates the Polarization of Uterine Macrophages During the Peri-Implantation Period

Uterine M1/M2 macrophages activation states undergo dynamic changes throughout pregnancy, and inappropriate macrophages polarization can cause adverse pregnancy outcomes, especially during the peri-implantation period. Our previous studies have confirmed that Cytochrome P450 26A1 (CYP26A1) can affect embryo implantation by regulating uterine NK cells and DCs. The aim of this study was to investigate whether CYP26A1 regulates the polarization of uterine macrophages in early pregnancy. Here, we observed that Cyp26a1 was significantly upregulated in M1 as compared with M2 of uterine macrophages, Raw264.7 and iBMDM. Knockdown of CYP26A1 in mice uterine significantly decreased the number of embryo implantation sites and the proportion of CD45⁺F4/80⁺CD206⁻ M1-like uterine macrophages. Primary uterine macrophages treated with anti-CYP26A1 antibody expressed significantly lower levels of M1 markers Nos2, Il1b, Il6 and Tnf-a. In CYP26A1 knockout Raw264.7 cells, the protein levels of M1 markers TNF-α, IL-6 and CD86 were significantly decreased as compared with the wild type cells. Moreover, CYP26A1 deficiency decreased the ability to produce nitric oxide and increased the phagocytosis capacity of Raw264.7 cells under M1 stimulation state. The re-introduction of CYP26A1 partially reversed the polarization levels of M1 in CYP26A1 knockout Raw264.7 cells. CYP26A1 may regulate the polarization of uterine macrophages to M1 through Stap1 and Slc7a2. In summary, these results indicate that CYP26A1 plays a significant role in macrophage polarization, and knockdown of CYP26A1 can cause insufficient M1 polarization during the peri-implantation period, which has adverse effects on blastocyst implantation.

Remodeling the Tumor Myeloid Landscape to Enhance Antitumor Antibody Immunotherapies

Among the diverse tumor resident immune cell types, tumor-associated macrophages (TAMs) are often the most abundant, possess an anti-inflammatory phenotype, orchestrate tumor immune evasion and are frequently associated with poor prognosis. However, TAMs can also be harnessed to destroy antibody-opsonized tumor cells through the process of antibody-dependent cellular phagocytosis (ADCP). Clinically important tumor-targeting monoclonal antibodies (mAb) such as Rituximab, Herceptin and Cetuximab, function, at least in part, by inducing macrophages to eliminate tumor cells via ADCP. For IgG mAb, this is mediated by antibody-binding activating Fc gamma receptors (FcγR), with resultant phagocytic activity impacted by the level of co-engagement with the single inhibitory FcγRIIb. Approaches to enhance ADCP in the tumor microenvironment include the repolarization of TAMs to proinflammatory phenotypes or the direct augmentation of ADCP by targeting so-called 'phagocytosis checkpoints'. Here we review the most promising new strategies targeting the cell surface molecules present on TAMs, which include the inhibition of 'don't eat me signals' or targeting immunostimulatory pathways with agonistic mAb and small molecules to augment tumor-targeting mAb immunotherapies and overcome therapeutic resistance.

Trophoblast-derived interleukin 9 mediates immune cell conversion and contributes to maternal-fetal tolerance

In the maternal-fetal crosstalk, fetal derived trophoblast cells can secret several molecules to regulate immune tolerance such as cytokines and chemokines, besides human leukocyte antigens (HLA) providing. However, the mechanism of these factors in pregnancy is still unknown. Our previous study showed that IL9 could be secreted by trophoblasts and exerted a positive effect on trophoblasts themselves through autocrine signaling. Given the immunoregulatory function of IL9 and its expression in trophoblasts, we hypothesize that IL9 contributes to maternal-fetal tolerance by regulating immune cells, especially CD14+ dendritic cells (DCs) and naïve CD4 + T cells who have essential roles in maternal-fetal immune tolerance. We performed a series of experiments, finding that HTR8/SVneo cells could secrete IL9 in vitro, and this secretion was decreased under hypoxia; both CD14 + DCs and naïve CD4 + T cells expressed IL9 receptors, indicating potential interactions among these cells. In CD14 + DCs, trophoblast-derived IL9 promoted the immature differentiation, and induced the secretion of Th2 cytokines, including IL4 and IL10, shifting the Th1/Th2 ratio to Th2. In naïve CD4 + T cells, IL9 also increased Foxp3 expression and promoted the secretion of Treg cytokines, including TGFβ and IL10, inhibiting pro-inflammatory Th17. Therefore, trophoblasts may act as fetal-derived immune cells to maintain maternal-fetal tolerance by secreting IL9. Given that trophoblast derived IL9 is decreased in preeclampsia, our study provides a new insight into maternal-fetal immunology and immunological disorders in abnormal pregnancy.

Plasmodium falciparum RIFIN is a novel ligand for inhibitory immune receptor LILRB2

Plasmodium falciparum causes the most severe form of malaria. Acquired immunity against P. falciparum provides insufficient protection even after repeated infections. Therefore, P. falciparum parasites might exploit inhibitory receptors for immune evasion. P. falciparum RIFINs are products of a multigene family consisting of 150-200 genes. Previously, we demonstrated that some RIFINs downregulate the immune response through the leukocyte immunoglobulin-like receptor (LILR) family inhibitory receptor, LILRB1, and leukocyte-associated immunoglobulin-like receptor 1, LAIR1. In this study, we further analyzed the expression of inhibitory receptor ligands on P. falciparum-infected erythrocytes and found that P. falciparum-infected erythrocytes expressed ligands for another LILR family inhibitory receptor, LILRB2, that recognizes HLA class I molecules as a host ligand. Furthermore, we identified that a specific RIFIN was a ligand for LILRB2 by using a newly developed RIFIN expression library. In addition, the domain 3 of LILRB2 was involved in RIFIN binding, whereas the domains 1 and 2 of LILRB2 were involved in the binding to HLA class I molecules. These results suggest that inhibitory receptor LILRB2 is also targeted by RIFIN for immune evasion of P. falciparum similar to LILRB1 and LAIR1.

Cytotrophoblasts suppress macrophage-mediated inflammation through a contact-dependent mechanism

PROBLEM

Gestational membrane (GM) infection provokes inflammation and can result in preterm prelabor rupture of membranes (PPROM). The choriodecidual layer of the GM includes decidual stromal cells (DSC), cytotrophoblasts (CTB), and macrophages (Mφ). Our laboratory has previously shown that DSCs suppress Mφ TNF-α production through secreted prostaglandin E₂ . We hypothesized that CTBs would also inhibit Mφ cytokine expression through secreted mediators.

METHOD OF STUDY

THP.1 Mφ-like cells with an NF-κB reporter construct or human blood monocyte-derived Mφ were co-cultured with the Jeg3 CTB cell line or primary human CTBs and challenged with group B streptococcus (GBS) or Toll-like receptor (TLR) agonists. Conditioned medium generated from CTB cultures was applied to Mφ cultures before infection or treatment. Alternatively, CTBs were co-incubated with, but physically separated from, Mφ and GBS or TLR-stimulated. NF-κB was assessed via alkaline phosphatase assay, and proinflammatory mediators were assessed by qRT-PCR and ELISA.

RESULTS

CTBs suppressed GBS- or TLR-stimulated Mφ NF-κB activity, and TNF-α and MMP9 production. Direct physical contact between CTBs and Mφ was required for full immunosuppression. Immunosuppression could be overcome by increasing the ratio of Mφ to CTB.

CONCLUSIONS

CTBs limit Mφ NF-κB activation and production of TNF-α and MMP9 through an as-yet unknown, cell-to-cell contact-mediated mechanism. This suppression is distinct from the PGE₂ -mediated Mφ TNF-α suppression by DSC, suggesting that DSCs and CTBs regulate Mφ inflammation through distinct mechanisms. How Mφ integrates these signals in an intact GM will be paramount to determining causes and prevention of PPROM.

The Role of Macrophages in Oocyte Donation Pregnancy: A Systematic Review

The embryo of an oocyte donation (OD) pregnancy is completely allogeneic to the mother, which leads to a more serious challenge for the maternal immune system to tolerize the fetus. It is thought that macrophages are essential in maintaining a healthy pregnancy, by acting in immunomodulation and spiral arterial remodeling. OD pregnancies represent an interesting model to study complex immunologic interactions between the fetus and the pregnant woman since the embryo is totally allogeneic compared to the mother. Here, we describe a narrative review on the role of macrophages and pregnancy and a systematic review was performed on the role of macrophages in OD pregnancies. Searches were made in different databases and the titles and abstracts were evaluated by three independent authors. In total, four articles were included on OD pregnancies and macrophages. Among these articles, some findings are conflicting between studies, indicating that more research is needed in this area. From current research, we could identify that there are multiple subtypes of macrophages, having diverse biological effects, and that the ratio between subtypes is altered during gestation and in aberrant pregnancy. The study of macrophages’ phenotypes and their functions in OD pregnancies might be beneficial to better understand the maternal-fetal tolerance system.

IL-13-regulated Macrophage Polarization during Granuloma Formation in an In Vitro Human Sarcoidosis Model

The mechanisms underlying abnormal granuloma formation in patients with sarcoidosis are complex and remain poorly understood. A novel in vitro human granuloma model was used to determine the molecular mechanisms of granuloma genesis in patients with sarcoidosis in response to putative disease-causing mycobacterial antigens. Peripheral blood mononuclear cells (PBMCs) from patients with active sarcoidosis and from normal, disease-free control subjects were incubated for 7 days with purified protein derivative-coated polystyrene beads. Molecular responses, as reflected by differential expression of genes, extracellular cytokine patterns, and cell surface receptor expression, were analyzed. Unbiased systems biology approaches were used to identify signaling pathways engaged during granuloma formation. Model findings were compared with human lung and mediastinal lymph node gene expression profiles. Compared with identically treated PBMCs of control subjects (n = 5), purified protein derivative-treated sarcoidosis PBMCs (n = 6) were distinguished by the formation of cellular aggregates resembling granulomas. Ingenuity Pathway Analysis of differential expression gene patterns identified molecular pathways that are primarily regulated by IL-13, which promotes alternatively activated (M2) macrophage polarization. M2 polarization was further demonstrated by immunohistochemistry performed on the in vitro sarcoidosis granuloma-like structures. IL-13-regulated gene pathways were confirmed in human sarcoidosis lung and mediastinal lymph node tissues. The in vitro human sarcoidosis granuloma model provides novel insights into early granuloma formation, particularly IL-13 regulation of molecular networks that regulate M2 macrophage polarization. M2 macrophages are predisposed to aggregation and multinucleated giant cell formation, which are characteristic features of sarcoidosis granulomas. Clinical trial registered with www.clinicaltrials.gov (NCT01857401).

Dynamic Function and Composition Changes of Immune Cells During Normal and Pathological Pregnancy at the Maternal-Fetal Interface

A successful pregnancy requires a fine-tuned and highly regulated balance between immune activation and embryonic antigen tolerance. Since the fetus is semi-allogeneic, the maternal immune system should exert tolerant to the fetus while maintaining the defense against infection. The maternal-fetal interface consists of different immune cells, such as decidual natural killer (dNK) cells, macrophages, T cells, dendritic cells, B cells, and NKT cells. The interaction between immune cells, decidual stromal cells, and trophoblasts constitute a vast network of cellular connections. A cellular immunological imbalance may lead to adverse pregnancy outcomes, such as recurrent spontaneous abortion, pre-eclampsia, pre-term birth, intrauterine growth restriction, and infection. Dynamic changes in immune cells at the maternal-fetal interface have not been clearly stated. While many studies have described changes in the proportions of immune cells in the normal maternal-fetus interface during early pregnancy, few studies have assessed the immune cell changes in mid and late pregnancy. Research on pathological pregnancy has provided clues about these dynamic changes, but a deeper understanding of these changes is necessary. This review summarizes information from previous studies, which may lay the foundation for the diagnosis of pathological pregnancy and put forward new ideas for future studies.

Role of Macrophages in Pregnancy and Related Complications

Macrophages (MФs) are the leukocytes produced from differentiation of monocytes and are located in almost all tissues of human body. They are involved in various processes, such as phagocytosis, innate and adaptive immunity, proinflammatory (M1) and anti-inflammatory (M2) activity, depending on the tissue microenvironment. They play a crucial role in pregnancy, and their dysfunction or alteration of polarity is involved in pregnancy disorders, like preeclampsia, recurrent spontaneous abortion, infertility, intrauterine growth restriction, and preterm labor. About 50-60% of decidual leukocytes are natural killer (NK) cells followed by MФs (the second largest population). MФs are actively involved in trophoblast invasion, tissue and vascular remodeling during early pregnancy, besides their role as major antigen-presenting cells in the decidua. These cells have different phenotypes and polarities in different stages of pregnancy. They have also been observed to enhance tumor growth by their anti-inflammatory activity (M2 type) and prevent immunogenic rejection. Targeted alteration of polarity (M1-M2 or vice versa) could be a major focus in the future treatment of pregnancy complications. This review is focused on the role of MФs in pregnancy, their involvement in pregnancy disorders, and decidual MФs as possible therapeutic targets for the treatment of pregnancy complications.

Tacrolimus treatment for infertility related to maternal-fetal immune interactions

Many approaches have been used to achieve successful pregnancies in patients with infertility, though existing treatments remain unsatisfactory in patients with infertility caused by abnormal maternal-fetal immunity. However, our understanding of the immunological aspects of infertility has steadily progressed, aided by recent research into organ transplantation and cancer. The results of these recent analyses have led to the development and evaluation of several candidate immunological treatments, but the use of immunological treatments remains a novel approach. The current paper presents the hypothesis that tacrolimus may have potential as a candidate agent for the treatment of maternal-fetal immunity-related infertility.

Biomarkers in Fetomaternal Tolerance

Multiple mechanisms of tolerance operate in the immune cross-talk at the fetomaternal interface, contributing to successful pregnancy outcome. The cross-talk includes interaction between various cell subsets and between cytokines and molecules of the endocrine system. A depiction of how all these components interact with each other and contribute to tolerance of the fetus is not clearly understood. Dysregulation in one or more of these mechanisms leads to fetal loss. Few effective biomarkers are available that can safely predict fetal loss. This review discusses some potential biomarkers that can predict failure of tolerance at the fetomaternal interface.

Blocking immunoinhibitory receptor LILRB2 reprograms tumor-associated myeloid cells and promotes antitumor immunity

Tumor-associated myeloid cells maintain immunosuppressive microenvironments within tumors. Identification of myeloid-specific receptors to modulate tumor-associated macrophage and myeloid-derived suppressor cell (MDSC) functions remains challenging. The leukocyte immunoglobulin-like receptor B (LILRB) family members are negative regulators of myeloid cell activation. We investigated how LILRB targeting could modulate tumor-associated myeloid cell function. LILRB2 antagonism inhibited receptor-mediated activation of SHP1/2 and enhanced proinflammatory responses. LILRB2 antagonism also inhibited AKT and STAT6 activation in the presence of M-CSF and IL-4. Transcriptome analysis revealed that LILRB2 antagonism altered genes involved in cell cytoskeleton remodeling, lipid/cholesterol metabolism, and endosomal sorting pathways, as well as changed differentiation gene networks associated with inflammatory myeloid cells as opposed to their alternatively activated phenotype. LILRB2 blockade effectively suppressed granulocytic MDSC and Treg infiltration and significantly promoted in vivo antitumor effects of T cell immune checkpoint inhibitors. Furthermore, LILRB2 blockade polarized tumor-infiltrating myeloid cells from non-small cell lung carcinoma tumor tissues toward an inflammatory phenotype. Our studies suggest that LILRB2 can potentially act as a myeloid immune checkpoint by reprogramming tumor-associated myeloid cells and provoking antitumor immunity.

Interleukin-10-Producing DC-10 Is a Unique Tool to Promote Tolerance Via Antigen-Specific T Regulatory Type 1 Cells

The prominent role of tolerogenic dendritic cells (tolDCs) in promoting immune tolerance and the development of efficient methods to generate clinical grade products allow the application of tolDCs as cell-based approach to dampen antigen (Ag)-specific T cell responses in autoimmunity and transplantation. Interleukin (IL)-10 potently modulates the differentiation and functions of myeloid cells. Our group contributed to the identification of IL-10 as key factor in inducing a subset of human tolDCs, named dendritic cell (DC)-10, endowed with the ability to spontaneously release IL-10 and induce Ag-specific T regulatory type 1 (Tr1) cells. We will provide an overview on the role of IL-10 in modulating myeloid cells and in promoting DC-10. Moreover, we will discuss the clinical application of DC-10 as inducers of Ag-specific Tr1 cells for tailoring Tr1-based cell therapy, and as cell product for promoting and restoring tolerance in T-cell-mediated diseases.

LILRB receptor-mediated regulation of myeloid cell maturation and function

The leukocyte immunoglobulin-like receptor (LILR) family comprises a set of paired immunomodulatory receptors expressed among human myeloid and lymphocyte cell populations. While six members of LILR subfamily A (LILRA) associate with membrane adaptors to signal via immunoreceptor tyrosine-based activating motifs (ITAM), LILR subfamily B (LILRB) members signal via multiple cytoplasmic immunoreceptor tyrosine-based inhibitory motifs (ITIM). Ligand specificity of some LILR family members has been studied in detail, but new perspective into the immunoregulatory aspects of this receptor family in human myeloid cells has been limited. LILRB receptors and the murine ortholog, paired immunoglobulin-like receptor B (PIRB), have been shown to negatively regulate maturation pathways in myeloid cells including mast cells, neutrophils, dendritic cells, as well as B cells. Our laboratory further demonstrated in mouse models that PIRB regulated functional development of myeloid-derived suppressor cell and the formation of a tumor-permissive microenvironment. Based on observations from the literature and our own studies, our laboratory is focusing on how LILRs modulate immune homeostasis of human myeloid cells and how these pathways may be targeted in disease states. Integrity of this pathway in tumor microenvironments, for example, permits a myeloid phenotype that suppresses antitumor adaptive immunity. This review presents the evidence supporting a role of LILRs as myeloid cell regulators and ongoing efforts to understand the functional immunology surrounding this family.

Immunosuppressive treatment using tacrolimus promotes pregnancy outcome in infertile women with repeated implantation failures

PROBLEM

We aim to investigate whether the peripheral blood T helper (Th) 1 cell level could predict pregnancy outcome in patients who have experienced repeated implantation failure (RIF, three or more) after ART cycles.

METHOD OF STUDY

This is a prospective cohort study of total 124 women with RIF who showed elevated Th1/Th2 (CD4⁺ IFN-γ⁺ /CD4⁺ IL-4⁺ ) cell ratios (≥10.3) and received tacrolimus at Sugiyama Clinic between November 2011 and July 2016. Patients were divided into three groups as per Th1 cell levels: Th1 level of <22.8 as Low; 22.8 to <28.8 as Middle, and 28.8 or greater as High group. The study patients received daily dose of tacrolimus 1-3 mg based on initial Th1/Th2 cell ratio.

RESULTS

The clinical pregnancy rates of Low, Middle, and High groups were 48.8%, 43.9%, and 33.3%, respectively (P=NS), with tacrolimus treatment. The ongoing pregnancy/delivery rate of Low group (46.3%) was significantly higher than that of High group (21.4%, P<.05). Middle group (34.3%) had higher success rate than High group, albeit without statistical significant.

CONCLUSION

We confirm our previous report that Th1/Th2 ratio can predict ART outcomes in patients with RIF and immunosuppressant treatment with tacrolimus, and peripheral blood Th1 cell levels were negatively correlated with pregnancy outcome.

Ultrastructure alteration of decidual natural killer cells in women with unexplained recurrent miscarriage: a possible association with impaired decidual vascular remodelling

This study aimed to evaluate the extent of remodelling of intra-decidual segments of the spiral arteries in human deciduas between the 6th and 10th gestational weeks in women with unexplained recurrent miscarriages (RM) in comparison to gestational-matched controls. A possible association with the number, immunoexpressive behaviour and ultrastructural changes of decidual natural killer cells (dNKCs) was investigated. Decidual biopsies were obtained from RM cases (n = 40) and women with no history of spontaneous miscarriage and at least one live birth at term (n = 30). Staining was performed using PAS, anti-CD34 and anti-CD56 antibodies, using an avidin-biotin-peroxides technique. Analysis by means of light and transmission electron microscopy was employed. To determine the extent of remodelling of decidual vessels, a quantitative score was analysed using histological criteria of vascular transformation and then related to the number of CD56(+) dNKCs. In RM, dNKCs were distributed among decidual cells and around the vessels. They possessed numerous polyploidic protrusions on cell membranes crossing from one cell to another. The cells became more irregular and exhibited heterogeneous electron-dense granules in their cytoplasm compared to controls. The non-remodelling score and number of dNKCs were significantly increased in RM group (p < 0.001). The number of dNKCs was significantly correlated with the scores in both control (r = 0.491; p = 0.006) and RM (r = 0.852; p < 0.001) groups. It appears that dNKCs play a key role in impaired decidual artery remodelling that may be involved with early RM. This may be due to increased numbers of cells or impaired cellular interactions resulting from alterations to the ultrastructure.

Placental macrophages are impaired in chorioamnionitis, an infectious pathology of the placenta

Pregnancy is dependent on maternal-fetal tolerance that may be compromised because of infections or inflammation of the placenta. In this study, we examined whether the context of placental immune tolerance affected the functions of resident macrophages and if their functions were altered during chorioamnionitis, an infectious pathology of the placenta. Macrophages from at-term placentas expressed CD14, exhibited macrophage microbicidal functions, but were less inflammatory than monocyte-derived macrophages. Moreover, placental macrophages spontaneously matured into multinucleated giant cells (MGCs), a property not exhibited by monocyte-derived macrophages, and we detected MGCs of myeloid origin in placental tissue. Compared with placental macrophages, MGCs exhibited a specific phenotype and gene expression signature, consisting of increased cytoskeleton-associated gene expression along with depressed expression of inflammatory response genes. Furthermore, placental macrophages from patients with chorioamnionitis were unable to form MGCs, but this defect was partially corrected by incubating these placental macrophages with control trophoblast supernatants. MGCs formation likely serves to regulate their inflammatory and cytocidal activities in a context that imposes semiallograft acceptance and defense against pathogens.

Phenotypical characteristics of peripheral blood monocytes in normal pregnancy and gestosis

Monocyte migration from the peripheral blood to the uterine decidual tissue is essential for the regulation of placental development. We evaluated the phenotypical changes in the peripheral blood monocytes in pregnant women. The peripheral blood counts of monocytes expressing CD11b, CD47, and integrin β7 were elevated in women with normal gestation in comparison with nonpregnant women; the intensity of CD62P, CD11b, CD11c, CD29, CD31, and CD54 expression was higher in pregnancy. The counts of monocytes expressing adhesion molecules were similar in normal pregnancy and gestosis. Gestosis was characterized by higher counts of monocytes expressing IFN-γ receptor (CD119) and more intense expression of this receptor. Changes in the monocyte phenotype can promote their adhesion to the uterine vascular endothelium and further migration of these cells to the decidual tissue.

HLA-G expressing DC-10 and CD4(+) T cells accumulate in human decidua during pregnancy

Multiple mechanisms underlie the surprising willingness of mothers to tolerate the semi-allogeneic fetal tissues during pregnancy. Chief among these is the expression of the HLA-G molecules that has been largely demonstrated to be responsible for reprogramming the local maternal immune response towards tolerance. We recently identified a subset of tolerogenic dendritic cells, DC-10 that secrete high amounts of IL-10 and express high levels of HLA-G and its ligand ILT4. DC-10 are present in the peripheral blood and are essential in inducing adaptive regulatory T cells. We investigated the presence of DC-10 and HLA-G-expressing CD4⁺ T cells in human decidua in the first trimester of pregnancy. Results showed that these cells are highly represented in human decidua as compared to the peripheral blood. This is the first report describing decidual DC-10 and CD4⁺HLA-G⁺ T cells, strongly suggesting that they may accumulate or be induced at the fetal maternal interface to promote tolerance.

Congenital and oral transmission of American trypanosomiasis: an overview of physiopathogenic aspects

Chagas disease or American trypanosomiasis is a pathology affecting about 8-11 million people in Mexico, Central America, and South America, more than 300 000 persons in the United States as well as an indeterminate number of people in other non-endemic countries such as USA, Spain, Canada and Switzerland. The aetiological agent is Trypanosoma cruzi, a protozoan transmitted by multiple routes; among them, congenital route emerges as one of the most important mechanisms of spreading Chagas disease worldwide even in non-endemic countries and the oral route as the responsible of multiple outbreaks of acute Chagas disease in regions where the vectorial route has been interrupted. The aim of this review is to illustrate the recent research and advances in host-pathogen interaction making a model of how the virulence factors of the parasite would interact with the physiology and immune system components of the placental barrier and gastrointestinal tract in order to establish a response against T. cruzi infection. This review also presents the epidemiological, clinical and diagnostic features of congenital and oral Chagas disease in order to update the reader about the emerging scenarios of Chagas disease transmission.

Smoking during pregnancy influences the maternal immune response in mice and humans

OBJECTIVE

During pregnancy the maternal immune system has to adapt its response to accommodate the fetus. The objective of this study was to analyze the effects of smoking on the maternal immune system.

STUDY DESIGN

First-trimester decidual tissue and peripheral blood of smoking and nonsmoking women were analyzed by real time reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry. A mouse model was used to further analyze the effects of smoking. Murine tissue was analyzed by flow cytometry, real-time RT-PCR, and immunohistochemistry.

RESULTS

Smoking caused lower percentages of viable pups in mice and lower birthweights in humans. Smoking mothers, both mice and human, had more natural killer cells and inflammatory macrophages locally, whereas systemically they had lower percentages of regulatory T cells than nonsmoking controls.

CONCLUSION

Maternal smoke exposure during pregnancy influences local and systemic immune responses in both women and mice. Such changes may be involved in adverse pregnancy outcomes in smoking individuals.

Expression of human leukocyte antigen G is associated with prognosis in nasopharyngeal carcinoma

Human leukocyte antigen G (HLA-G) has multiple immune regulatory functions including the induction of immune tolerance in malignancies. The roles of HLA-G have not been investigated in nasopharyngeal carcinoma (NPC). This study is aimed to evaluate the role of HLA-G as prognostic factor for NPC patients as well as its role in the immune regulation. Western assays showed high HLA-G expression in NPC cell lines, but low in the immortalized nasopharyngeal epithelial cell line NP69. HLA-G protein was further detected in 79.2% of 552 NPC specimens with immunohistochemistry (IHC), but not in normal nasopharyngeal epithelium tissue. Moreover, high expression of HLA-G predicted poor survival of NPC patients and positively correlated with tumor N classification and recurrence or metastasis. Multivariate analysis indicated that HLA-G was an independent and unfavorable prognostic factor. Furthermore, the presence of CD68+ macrophages and IL-10 were also examined, which are two prognostic markers of NPC and important factors for regulating immune surveillance. The correlations of HLA-G with these two immune factors were revealed in NPC tissues. Taken together, our results suggest that HLA-G is an independent biomarker for NPC prognosis, and HLA-G might contribute to NPC progression, which might jointly regulate immune surveillance in NPC together with macrophages and IL-10.

Key cellular components and interactive histocompatibility molecules regulating tolerance to the fetal allograft

Implantation is a major landmark in life. It involves the correct apposition of the embryo in the maternal endometrium. The cellular environment influences placenta development, and direct contact of the fetus with maternal tissues is achieved through decidual cells. At the decidua, and at systemic level, the correct balance of cells potentially acting as antigen-presenting cells and histocompatibility products play a pivotal role in achieving feto-maternal tolerance. Here, we review some of the current issues associated with the interplay between cells and molecules needed for pregnancy development.

The complement system at the embryo implantation site: friend or foe?

An inflammatory-like process and vascular remodeling represent the main changes that occur in decidua in the early phase of pregnancy. These changes are partly induced by trophoblast cells that colonize the decidua and are also contributed by the complement system, which can easily be activated as a result of tissue remodeling. Local control by several complement regulators including surface-bound and soluble molecules is critical to prevent complement-mediated tissue damage in normal pregnancy. C7 expressed on the endothelial cells (ECs) surface has been recognized as a novel complement regulator involved in the control of the proinflammatory effect of the terminal complement complex. The protective role of placental complement regulators in pregnancy is underscored by the recent finding of an association of preeclampsia with mutations in the genes encoding for some of these proteins. Complement components produced at feto-maternal interface serve an important function in placental development. C1q synthesized by decidual ECs and expressed on the cell surface is particularly important in this regard because it acts as a molecular bridge between endovascular trophoblast and ECs. C1q is also produced by extravillous trophoblast and is used to favor trophoblast migration through the decidua. Defective expression of C1q by trophoblast is associated with impaired trophoblast invasion of decidua and may have important implications in pregnancy disorders such as preeclampsia characterized by reduced vascular remodeling.

Altered expression of immune-associated genes in first-trimester human decidua of pregnancies later complicated with hypertension or foetal growth restriction

During pregnancy the maternal immune system has to coordinate uterine spiral-artery remodelling, trophoblast invasion, and acceptance of the semi-allogenic fetus simultaneously. As dysregulation of the immune system is associated with adverse pregnancy outcomes, we analysed first-trimester deciduas of pregnancies for immune parameters in later complicated pregnancies. Higher IL6 and macrophage mRNA expression, and lower ratios of regulatory macrophages were found in first-trimester deciduas of pregnancies later complicated with pregnancy-induced hypertension. Lower Gata3 (Th2) mRNA expression was found in deciduas of pregnancies with later foetal growth restriction. Our results suggest that adverse pregnancy outcomes are associated with immunological disturbances in first-trimester deciduas.

Pregnancy and rheumatoid arthritis: insights into the immunology of fetal tolerance and control of autoimmunity

It has long been recognized that symptoms and signs of rheumatoid arthritis (RA) frequently improve spontaneously during pregnancy, only to flare postpartum. Although the mechanisms behind this phenomenon remain poorly understood, there is growing interest in the immunologic changes that occur during healthy pregnancy as a possible explanation. Because the maternal immune system must adapt during pregnancy to accept the semi-allogeneic fetus, it has been hypothesized that these natural changes induced by pregnancy on maternal immune regulatory cells may have the additional benefit of controlling the immunopathology driving disease activity in RA. Here, we review our current understanding on the effects of pregnancy on RA and highlight some of the recent literature related to advancing our understanding on the immunology of pregnancy as well as the immunologic changes in RA during pregnancy.

Barriers of the Human Organism and Their Achilles’ Heels

The human body is covered by barriers separating it from the external and internal surroundings. The “milieu enterieur” has to be stabilised in spite of the variable external and internal conditions of toxic, osmotic, microbial and climatic environmental circumstances. This first line of barriers is composed of skin and mucous membranes of complicated structures.

A second line of barrier system is present in our organisms. Certain organs have to be separated from the immune system and other parts of the body because of evolutionary reasons (eye-bulb and testicles) because of unique proteins “unknown” for the acquired immune system. The blood-brain barrier (BBB) is providing enhanced safety circumstances for the central nervous system. The second line of barriers is represented by the special properties of the capillary endothelial system.

The maternal-fetal barrier is the most complex. At the maternal fetal interface two individuals of two different haplotypes has to be live 9 months separated by a very complicated dynamic barrier.

The placenta is the organ, which is separating the maternal and fetal tissues. Similar to others the bidirectional transport of gasses, metabolites, cells, proteins, regulatory substances, are transported by active or passive transcellular and intercellular mechanisms.

The fetal immune system develops immunotolerance to all maternal cells and antigens transferred transplacentally. The problem is to mitigate the maternal immune system to tolerate the paternal haplotype of the fetus. In the case of normal pregnancy a complex series of physiological modifications can solve the problem without harmful consequences to the mother and fetus.

The outermost contact cells of trophoblasts express instead of HLA-class Ia and class II antigens non-variable HLA-C, HLA-E, HLA-F and HLA-G antigens. The first consequence of this is reduction of the activity of maternal natural killer cells and maternal dendritic cells;

Progesteron, micro-RNA and mediators influence the development of T effector-cells. The production of soluble HLA-G(5 and 6) and IL-10 supports the differentiation of Th-2 CD4⁺ helper cells, reducing the ability of maternal cells to kill fetal cells.

Series of receptors and costimulators are expressed by the different lines of semi-allogenic trophoblast cells to bind HLA-G and mitigate maternal immune response;

The maternal immunotolerance is further facilitated by the activation of CD4⁺CD25^brightFoxp3⁺ regulatory T (T_REG) cells.

Infections have to be prevented during pregnancy. The cells of placenta express 10 Toll-like receptors a group of pattern recognition receptors responsible for innate immunity. The interferon level is also higher in the placental tissues than in the somatic fetal or maternal cells.

The complement system is also adapted to the requirements of the pregnancy and fetal damage is inhibited by the production of “assymmetric IgG antibodies” under hormonal and placental-regulation. These modifications prevent the activation of complement, cytotoxic activity, opsonising ability, antigen clearance and precipitating activity of the molecules.

The Achilles’ heels of the different barriers are regularly found by virus infections. Lamina cribrosa of the blood-brain barrier, optical nerve of the eyes, etc. the risk factors of the maternal-fetal barrier has been summarised in Table 1.1.

Gene expression in placentation of farm animals: an overview of gene function during development

Eutherian mammals share a common ancestor that evolved into two main placental types, i.e., hemotrophic (e.g., human and mouse) and histiotrophic (e.g., farm animals), which differ in invasiveness. Pregnancies initiated with assisted reproductive techniques (ART) in farm animals are at increased risk of failure; these losses were associated with placental defects, perhaps due to altered gene expression. Developmentally regulated genes in the placenta seem highly phylogenetically conserved, whereas those expressed later in pregnancy are more species-specific. To elucidate differences between hemotrophic and epitheliochorial placentae, gene expression data were compiled from microarray studies of bovine placental tissues at various stages of pregnancy. Moreover, an in silico subtractive library was constructed based on homology of bovine genes to the database of zebrafish - a nonplacental vertebrate. In addition, the list of placental preferentially expressed genes for the human and mouse were collected using bioinformatics tools (Tissue-specific Gene Expression and Regulation [TiGER] - for humans, and tissue-specific genes database (TiSGeD) - for mice and humans). Humans, mice, and cattle shared 93 genes expressed in their placentae. Most of these were related to immune function (based on analysis of gene ontology). Cattle and women shared expression of 23 genes, mostly related to hormonal activity, whereas mice and women shared 16 genes (primarily sexual differentiation and glycoprotein biology). Because the number of genes expressed by the placentae of both cattle and mice were similar (based on cluster analysis), we concluded that both cattle and mice were suitable models to study the biology of the human placenta.