Lymphocytes in Placental Tissues: Immune Regulation and Translational Possibilities for Immunotherapy

Profiling of Immunomodulatory Genes and Quantification of CD25+ Cells in Different Types of Early Pregnancy Loss

INTRODUCTION

Maternal regulatory T (Treg) cells play a pivotal role in establishing general immune homeostasis in the decidua for maintenance of pregnancy. We aimed in this study to investigate the relationship between mRNA expression of immunomodulatory genes and CD25+ Treg cells with early pregnancy losses.

METHODS

Our study included 3 groups of early pregnancy losses including sporadic spontaneous abortions, recurrent spontaneous abortions, sporadic spontaneous abortions post IVF treatment and the control group. We performed RT-PCR for analyzing mRNA expression levels of 6 immunomodulatory genes and CD25 immunohistochemistry for quantification of Treg cells.

RESULTS

Only FOXP3, CD274 (PDL1), and TGFβ1 mRNA expression levels were significantly decreased in the miscarriage groups in comparison to the control group, whereas there was no significant mRNA expression change of CD4, IL2RA, and IL10. We also found significantly lower number of CD25+ cells in the miscarriages.

CONCLUSION

We conclude that decreased expression of FOXP3 and PD-L1 may play a significant role in the pathogenesis of spontaneous abortion cases whereas decreased expression of TGFβ1 gene may be associated with the occurrence of early loss in IVF-treated pregnancies. Additional immunoprofiling of Treg cell population is needed to quantify Treg cells in early pregnancy losses.

Research progress in the role of CD38 in clinical tumor treatment

Tumor is one of the ten leading causes of death in the world. Traditional tumor treatments include surgery, radiation therapy, and chemotherapy. With the development of immune checkpoint blockade therapy targeting the programmed death 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) axis, the number of cancers in solid tumors has increased. Changes in the immunometabolic microenvironment have been shown to be important regulators of innate suppression of immune cell function and acquired resistance to immunotherapy. As a new target, CD38 is an enzyme that produces immunosuppressive metabolites (such as adenosine), which can be used in combination with immunotherapy to improve the clinical efficacy of tumor therapy, and can also be used as an indicator for understanding tumor immunotherapy response.

The expression of miR-17 and miR-29a in placenta-derived exosomes in LPS-induced abortion mice model: An experimental study

Background

The expression pattern of microRNAs in placenta-derived exosomes plays a crucial role in the regulation of immune responses and inflammation at the fetal–maternal interface.

Objective

Considering the immunomodulatory properties of miR-17 and miR-29a, we determined their expression levels in placenta-derived exosomes in a lipopolysaccharide (LPS)-induced abortion mice model.

Materials and Methods

A total of 14 pregnant BALB/c mice, aged 6–8 wk, were randomly divided into two groups (n = 7/each) on the gestational day 11.5. While the mice in the experimental group were treated with LPS, those in the control group were treated with Phosphate buffered saline; 5 hr after the treatment, the placental cells were isolated and cultured for 48 hr. Then, the cell culture supernatants were collected and used for isolation of exosomes. The isolated exosomes were confirmed by western blot and scanning electron microscopy. The miRNAs were then extracted from exosomes, and cDNA synthesized. The expression levels of miR-17 and miR-29a were evaluated by quantitative real-time PCR analysis.

Results

Our results showed that the expression levels of miR-29a in placenta-derived exosomes obtained from the experimental group increased significantly compared to the control group. Also, the expression levels of miR-17 in the placenta-derived exosomes obtained from the experimental group were found to decrease; however, it did not show significant changes compared with the control group (p > 0.05).

Conclusion

Inflammatory reactions at the fetal–maternal interface can alter miRNAs expression patterns in placenta-derived exosomes, especially miRNAs with immunomodulatory effects such as miR-29a.

Endogenous retrovirus-encoded Syncytin-2 contributes to exosome-mediated immunosuppression of T cells†

Modulation of the activation status of immune cell populations during pregnancy depends on placental villous cytotrophoblast (VCT) cells and the syncytiotrophoblast (STB). Failure in the establishment of this immunoregulatory function leads to pregnancy complications. Our laboratory has been studying Syncytin-2 (Syn-2), an endogenous retroviral protein expressed in placenta and on the surface of placental exosomes. This protein plays an important role not only in STB formation through its fusogenic properties, but also through its immunosuppressive domain (ISD). Considering that Syn-2 expression is importantly reduced in preeclamptic placentas, we were interested in addressing its possible immunoregulatory effects on T cells. Activated Jurkat T cells and peripheral blood mononuclear cells (PBMCs) were treated with monomeric or dimerized version of a control or a Syn-2 ISD peptide. Change in phosphorylation levels of ERK1/2 MAP kinases was selectively noted in Jurkat cells treated with the dimerized ISD peptide. Upon incubation with the dimerized Syn-2 ISD peptide, significant reduction in Th1 cytokine production was further demonstrated by ELISA and Human Th1/Th2 Panel Multi-Analyte Flow Assay. To determine if exosome-associated Syn-2 could also be immunosuppressive placental exosomes were incubated with activated Jurkat and PBMCs. Quantification of Th1 cytokines in the supernatants revealed severe reduction in T cell activation. Interestingly, exosomes from Syn-2-silenced VCT incubated with PBMCs were less suppressive when compared with exosome derived from VCT transfected with control small interfering RNA (siRNA). Our results suggest that Syn-2 is an important immune regulator both locally and systemically, via its association with placental exosomes.

TIGIT and CD155 as Immune-Modulator Receptor and Ligand on CD4+ T cells in Preeclampsia Patients

One of the main characteristics of preeclampsia (PE) is systemic inflammation. CD4⁺ FoxP3⁺ cells play a critical role in both fetomaternal tolerance and successful pregnancy. T-cell immunoglobulin, as well as immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT)/CD155 pathway, possesses critical parts in the development of normal pregnancy by promoting regulatory T (Treg) cells. However, in PE, the relationship between TIGIT/CD155 and Treg differentiation has not been entirely clarified. In the current report, we aimed to assess the frequency of TIGIT and CD155 expressing TCD4⁺ cells in both PE and healthy pregnant women, as well as evaluating the amount of inflammatory and inhibitory cytokines at both mRNA and protein levels before and after blocking TIGIT and CD155. In the present report, 59 healthy, and 52 PE patients were designated to obtain their venous blood. The isolation of peripheral blood mononuclear cells (PBMCs) was performed from the blood samples, and PBMCs were then cultured in the RPMI1640 medium. The percentage of CD155⁺ and TIGIT⁺ CD4⁺ cells was assessed by flow cytometry in PBMCs. Cell culture supernatants were utilized to evaluate the secretory levels of transforming growth factor beta (TGF-β), interleukin (IL)-10, IL-17, tumor necrosis factor alpha (TNF-α), and IL-1 β, using enzyme-linked immunosorbent assay technique in pregnant women with or without PE both before and after blocking TIGIT and CD155. The mRNA expression of Foxp3, TIGIT, CD155, SHP-1, TGF-β, IL-10, IL-17, TNF-α, and IL-1β was also assessed by qRT-PCR in PBMCs before and after blocking TIGIT and CD155 in both populations. The data showed a significant decrease in the frequency of TIGIT⁺ CD4⁺ and CD155⁺ CD4⁺ T cells in PE women, compared to the control group. Our results showed decreased protein and mRNA levels of TIGIT, CD155, IL-10, FOXP3, and SHP-1 in PE patients. In addition, significant improvements in the levels of IL-17, TNF-α, and IL-1β were observed in PE patients, as compared with the controls. However, blocking TIGIT and CD155 could increase these inflammatory cytokines and decrease anti-inflammatory cytokines. The data obtained in this report illustrated that there existed an imbalance between inflammatory and anti-inflammatory profiles, with an inflammatory status polarization, in PE patients. Additionally, TIGIT/CD155 showed a positive effect on immune regulation by activating ITIM, demonstrating the potential therapeutic value of the TIGIT/CD155 pathway in PE treatment. Also, using some proteins or materials that increased TIGIT/CD155 pathways activity and can be a therapeutic approach in PE.

β3-Adrenoceptors as Putative Regulator of Immune Tolerance in Cancer and Pregnancy

Understanding the mechanisms of immune tolerance is currently one of the most important challenges of scientific research. Pregnancy affects the immune system balance, leading the host to tolerate embryo alloantigens. Previous reports demonstrated that β-adrenergic receptor (β-AR) signaling promotes immune tolerance by modulation of NK and Treg, mainly through the activation of β2-ARs, but recently we have demonstrated that also β3-ARs induce an immune-tolerant phenotype in mice bearing melanoma. In this report, we demonstrate that β3-ARs support host immune tolerance in the maternal microenvironment by modulating the same immune cells populations as recently demonstrated in cancer. Considering that β3-ARs are modulated by oxygen levels, we hypothesize that hypoxia, through the upregulation of β3-AR, promotes the biological shift toward a tolerant immunophenotype and that this is the same trick that embryo and cancer use to create an aura of immune-tolerance in a competent immune environment. This study confirms the analogies between fetal development and tumor progression and suggests that the expression of β3-ARs represents one of the strategies to induce fetal and tumor immune tolerance.

Gasotransmitters in pregnancy: from conception to uterine involution

Gasotransmitters are endogenous small gaseous messengers exemplified by nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S or sulfide). Gasotransmitters are implicated in myriad physiologic functions including many aspects of reproduction. Our objective was to comprehensively review basic mechanisms and functions of gasotransmitters during pregnancy from conception to uterine involution and highlight future research opportunities. We searched PubMed and Web of Science databases using combinations of keywords nitric oxide, carbon monoxide, sulfide, placenta, uterus, labor, and pregnancy. We included English language publications on human and animal studies from any date through August 2018 and retained basic and translational articles with relevant original findings. All gasotransmitters activate cGMP signaling. NO and sulfide also covalently modify target protein cysteines. Protein kinases and ion channels transduce gasotransmitter signals, and co-expressed gasotransmitters can be synergistic or antagonistic depending on cell type. Gasotransmitters influence tubal transit, placentation, cervical remodeling, and myometrial contractility. NO, CO, and sulfide dilate resistance vessels, suppress inflammation, and relax myometrium to promote uterine quiescence and normal placentation. Cervical remodeling and rupture of fetal membranes coincide with enhanced oxidation and altered gasotransmitter metabolism. Mechanisms mediating cellular and organismal changes in pregnancy due to gasotransmitters are largely unknown. Altered gasotransmitter signaling has been reported for preeclampsia, intrauterine growth restriction, premature rupture of membranes, and preterm labor. However, in most cases specific molecular changes are not yet characterized. Nonclassical signaling pathways and the crosstalk among gasotransmitters are emerging investigation topics.

Effect for Human Genomic Variation During the BMP4-Induced Conversion From Pluripotent Stem Cells to Trophoblast

The role of genomic variation in differentiation is currently not well understood. Here, the genomic variations were determined with the whole-genome sequencing for three pairs of pluripotent stem cell lines and their corresponding BMP4-induced trophoblast cell lines. We identified ∼3,500 single nucleotide variations and ∼4,500 indels by comparing the genome sequenced data between the stem cell lines and the matched BMP4-induced trophoblast cell lines and annotated them by integrating the epigenomic and transcriptomic datasets. Relatively, introns enrich more variations. We found ∼45% (42 genes) of the differentially expressed genes in trophoblasts that associate genomic variations. Six variations, located at transcription factor binding sites where H3K4me3 and H3K27ac are enriched in both H1 and H1_BMP4, were identified. The epigenetic status around the genomic variations in H1 was similar to that in H1_BMP4. This means that the variation-associated gene’s expression change can not be attributed to epigenetic alteration. The genes associated with the six variations were upregulated in differentiation. We inferred that during the differentiation, an increased in the expression level of the MEF2C gene is due to a genomic variation in chromosomes 5: 88179358 A > G, which is at a binding site of TFs KLF16, NR2C2, and ZNF740 to MEF2C. Allele G shows a higher affinity to the TFs in the induced cells. The increased expression of MEF2C leads to an increased expression of TF MEF2C’s target genes, subsequently affecting the differentiation. Although genomic variation should not be a dominant factor in differentiation, we believe that genomic variation could indeed play a role in the differentiation from stem cells into trophoblast.

CD38, a Receptor with Multifunctional Activities: From Modulatory Functions on Regulatory Cell Subsets and Extracellular Vesicles, to a Target for Therapeutic Strategies

CD38 is a multifunctional cell surface protein endowed with receptor/enzymatic functions. The protein is generally expressed at low/intermediate levels on hematological tissues and some solid tumors, scoring the highest levels on plasma cells (PC) and PC-derived neoplasia. CD38 was originally described as a receptor expressed by activated cells, mainly T lymphocytes, wherein it also regulates cell adhesion and cooperates in signal transduction mediated by major receptor complexes. Furthermore, CD38 metabolizes extracellular NAD+, generating ADPR and cyclic ADPR. This ecto-enzyme controls extra-cellular nucleotide homeostasis and intra-cellular calcium fluxes, stressing its relevance in multiple physiopathological conditions (infection, tumorigenesis and aging). In clinics, CD38 was adopted as a cell activation marker and in the diagnostic/staging of leukemias. Quantitative surface CD38 expression by multiple myeloma (MM) cells was the basic criterion used for therapeutic application of anti-CD38 monoclonal antibodies (mAbs). Anti-CD38 mAbs-mediated PC depletion in autoimmunity and organ transplants is currently under investigation. This review analyzes different aspects of CD38's role in regulatory cell populations and how these effects are obtained. Characterizing CD38 functional properties may widen the extension of therapeutic applications for anti-CD38 mAbs. The availability of therapeutic mAbs with different effects on CD38 enzymatic functions may be rapidly translated to immunotherapeutic strategies of cell immune defense.

The Tolerogenic Function of Regulatory T Cells in Pregnancy and Cancer

Regulatory T cells, a subpopulation of suppressive T cells, are potent mediators of self-tolerance and essential for the suppression of triggered immune responses. The immune modulating capacity of these cells play a major role in both transplantation, autoimmune disease, allergy, cancer and pregnancy. During pregnancy, low numbers of regulatory T cells are associated with pregnancy failure and pregnancy complications such as pre-eclampsia. On the other hand, in cancer, low numbers of immunosuppressive T cells are correlated with better prognosis. Hence, maternal immune tolerance toward the fetus during pregnancy and the escape from host immunosurveillance by cancer seem to be based on similar immunological mechanisms being highly dependent on the balance between immune activation and suppression. As regulatory T cells hold a crucial role in several biological processes, they may also be promising subjects for therapeutic use. Especially in the field of cancer, cell therapy and checkpoint inhibitors have demonstrated that immune-based therapies have a very promising potential in treatment of human malignancies. However, these therapies are often accompanied by adverse autoimmune side effects. Therefore, expanding the knowledge to recognize the complexities of immune regulation pathways shared across different immunological scenarios is extremely important in order to improve and develop new strategies for immune-based therapy. The intent of this review is to highlight the functional characteristics of regulatory T cells in the context of mechanisms of immune regulation in pregnancy and cancer, and how manipulation of these mechanisms potentially may improve therapeutic options.

Early Pregnancy Human Decidua is Enriched with Activated, Fully Differentiated and Pro-Inflammatory Gamma/Delta T Cells with Diverse TCR Repertoires

Pregnancy is a state where high and stage-dependent plasticity of the maternal immune system is necessary in order to equilibrate between immunosuppression of harmful responses towards the fetus and ability to fight infections. TCR γδ cells have been implicated in the responses in infectious diseases, in the regulation of immune responses, and in tissue homeostasis and repair. The variety of functions makes γδ T cells a particularly interesting population during pregnancy. In this study, we investigated the proportion, phenotype and TCR γ and δ repertoires of γδ T cells at the maternal–fetal interface and in the blood of pregnant women using FACS, immunohistochemistry and spectratyping. We found an enrichment of activated and terminally differentiated pro-inflammatory γδ T-cell effectors with specific location in the human decidua during early pregnancy, while no significant changes in their counterparts in the blood of pregnant women were observed. Our spectratyping data revealed polyclonal CDR3 repertoires of the δ1, δ2 and δ3 chains and γ2, γ3, γ4 and γ5 chains and oligoclonal and highly restricted CDR3γ9 repertoire of γδ T cells in the decidua and blood of pregnant women. Early pregnancy induces recruitment of differentiated pro-inflammatory γδ T-cell effectors with diverse TCR repertoires at the maternal–fetal interface.