Hormonally controlled ILC antigen presentation potential is reduced during pregnancy

Human chorionic gonadotrophin indirectly activates peripheral γδT cells to produce interleukin-10 during early pregnancy

BACKGROUNDS

The immunomodulatory properties of human chorionic gonadotrophin (hCG) have been identified to be critical for successful pregnancy. However, the effects of hCG on peripheral γδT cells during early pregnancy have not been reported previously.

METHODS

We cocultured the purified γδT cells and peripheral blood mononuclear cells (PBMCs) with early pregnancy-relevant hCG concentrations and investigated the changes in the immune functional characteristics of γδT cells via flow cytometry assays.

RESULTS

The ratios of CD69+ and IL-10+ γδT cells were increased in early pregnant women compared to nonpregnant women. γδT cells expressed low levels of the mannose receptor (CD206) instead of the classical hCG/LH receptor for hCG. The direct treatment of purified γδT cells with early pregnancy-relevant hCG concentrations may have no significant effects on their immune functions. Interestingly, when PBMCs were treated with the same broad range of hCG concentrations, the ratios of CD69+ and IL-10+ γδT cells to total γδT cells were significantly increased.

CONCLUSION

Certain early pregnancy-relevant hCG concentrations could enhance the ratios of peripheral CD69+ and IL-10+ γδT cells, contributing to the activation of γδT cells and immunological tolerance during early pregnancy. However, these affects may not be strongly mediated by direct ligand-receptor interactions and they may highly depend on immune microenvironment. Our novel observations propose a perspective into the endocrine-immune dialog that exists between the fetus and maternal immune cells.

Immune Cell Functionality during Decidualization and Potential Clinical Application

Due to a vast influx in the secretory phase of the menstrual cycle, leukocytes represent 40-50% of the decidua at the time of implantation. Their importance for the implantation, maintenance of pregnancy, and parturition are known yet not fully understood. Thus, in idiopathic infertility, decidual immune-related factors are speculated to be the cause. In this review, the immune cell functions in the decidua were summarized, and clinical diagnostics, as well as interventions, were discussed. There is a rising number of commercially available diagnostic tools. However, the intervention options are still limited and/or poorly studied. In order for us to make big steps towards the proper use of reproductive immunology findings, we need to understand the mechanisms and especially support translational research.

Innate and Adaptive Immune Systems in Physiological and Pathological Pregnancy

The dynamic immunological changes occurring throughout pregnancy are well-orchestrated and important for the success of the pregnancy. One of the key immune adaptations is the maternal immune tolerance towards the semi-allogeneic fetus. In this review, we provide a comprehensive overview of what is known about the innate and adaptive immunological changes in pregnancy and the role(s) of specific immune cells during physiological and pathological pregnancy. Alongside this, we provided details of remaining questions and challenges, as well as future perspectives for this growing field of research. Understanding the immunological changes that occur can inform potential strategies on treatments for the optimal health of the neonate and pregnant individual both during and after pregnancy.

Oxygen regulates ILC3 antigen presentation potential and pregnancy-related hormone actions

Early pregnancy is marked by placentation and embryogenesis, which take place under physiological low oxygen concentrations. This oxygen condition is crucial for many aspects of placentation, trophoblast function, vascularization and immune function. Recently, a new family of innate lymphoid cells has been found to be expressed at the fetomaternal interface. Among these, type 3 innate lymphoid cells (ILC3) are important antigen presenting cells in the context of MHC-II. The expression of MHC-II on ILC3s during pregnancy is reduced. We tested the hypothesis that low oxygen concentrations reduce the potential of ILC3s to present antigens promoting fetal tolerance.Using an in vitro approach, NCR⁺ ILC3s generated from cord blood stem cell precursors were incubated under different O₂ concentrations in the presence or absence of the pregnancy-related hormones hCG and TGF-β1. The expression of MHC-II, accessory molecules and an activation marker were assessed by flow cytometry. We observed that 1% O₂ reduced the expression of the MHC-II molecule HLA-DR as compared to 21% O₂ and modulated the relative effects of hCG and TGF-β1.Our data indicate that low oxygen concentrations reduce the antigen presentation potential of NCR⁺ ILC3s and suggest that it may promote fetal tolerance during the first trimester of pregnancy.

Role of hormones in the pregnancy and sex-specific outcomes to infections with respiratory viruses

Pregnant women infected with pathogenic respiratory viruses, such as influenza A viruses (IAV) and coronaviruses, are at higher risk for mortality, hospitalization, preterm birth, and stillbirth. Several factors are likely to contribute to the susceptibility of pregnant individuals to severe lung disease including changes in pulmonary physiology, immune defenses, and effector functions of some immune cells. Pregnancy is also a physiologic state characterized by higher levels of multiple hormones that may impact the effector functions of immune cells, such as progesterone, estrogen, human chorionic gonadotropin, prolactin, and relaxin. Each of these hormones acts to support a tolerogenic immune state of pregnancy, which helps prevent fetal rejection, but may also contribute to an impaired antiviral response. In this review, we address the unique role of adaptive and innate immune cells in the control of pathogenic respiratory viruses and how pregnancy and specific hormones can impact their effector actions. We highlight viruses with sex-specific differences in infection outcomes and why pregnancy hormones may contribute to fetal protection but aid the virus at the expense of the mother's health.

Low Abundance Fusobacterium Nucleatum Supports Early Pregnancy Development - An In Vitro Study

Pregnancy success depends greatly on a balanced immune homeostasis. The detection of bacterial components in the upper reproductive tract in non-pregnant and pregnant women raised questions on its possible beneficial role in reproductive health. The local conditions that allow the presence of bacteria to harmonize with the establishment of pregnancy are still unknown. Among the described bacterial species in endometrial and placental samples, Fusobacterium nucleatum was found. It has been observed that F. nucleatum can induce tumorigenesis in colon carcinoma, a process that shares several features with embryo implantation. We propose that low concentrations of F. nucleatum may improve trophoblast function without exerting destructive responses. Inactivated F. nucleatum and E. coli were incubated with the trophoblastic cell lines HTR8/SVneo, BeWo, and JEG-3. Viability, proliferation, migratory capacity, invasiveness and the secretion of chemokines, other cytokines and matrix metalloproteinases were assessed. The presence of F. nucleatum significantly induced HTR8/SVneo invasion, accompanied by the secretion of soluble mediators (CXCL1, IL-6 and IL-8) and metalloproteinases (MMP-2 and MMP-9). However, as concentrations of F. nucleatum increased, these did not improve invasiveness, hindered migration, reduced cell viability and induced alterations in the cell cycle. Part of the F. nucleatum effects on cytokine release were reverted with the addition of a TLR4 blocking antibody. Other effects correlated with the level of expression of E-cadherin on the different cell lines tested. Low amounts of F. nucleatum promote invasion of HTR8/SVneo cells and induce the secretion of important mediators for pregnancy establishment. Some effects were independent of LPS and correlated with the expression of E-cadherin on trophoblasts.

Cord-Blood-Derived Professional Antigen-Presenting Cells: Functions and Applications in Current and Prospective Cell Therapies

Human umbilical cord blood (UCB) represents a valuable source of hematopoietic stem cells, particularly for patients lacking a matching donor. UCB provides practical advantages, including a lower risk of graft-versus-host-disease and permissive human leukocyte antigen mismatching. These advantageous properties have so far been applied for stem cell, mesenchymal stromal cell, and chimeric antigen receptor T cell therapies. However, UCB-derived professional antigen-presenting cells are increasingly being utilized in the context of immune tolerance and regenerative therapy. Here, we review the cell-specific characteristics as well as recent advancements in UCB-based cell therapies focusing on dendritic cells, monocytes, B lymphocytes, innate lymphoid cells, and macrophages.