Jelmer R. Prins

Seminal Fluid Regulates Accumulation of FOXP3+ Regulatory T Cells in the Preimplantation Mouse Uterus Through Expanding the FOXP3+ Cell Pool and CCL19-Mediated Recruitment

Regulatory T (Treg) cells facilitate maternal immune tolerance of the semiallogeneic conceptus in early pregnancy, but the origin and regulation of these cells at embryo implantation is unclear. During the preimplantation period, factors in the seminal fluid delivered at coitus cause expansion of a CD4+CD25+ putative Treg cell population in the para-aortic lymph nodes draining the uterus. Using flow cytometry, immunohistochemistry, and real-time quantitative PCR (qPCR) for the signature Treg cell transcription factor FOXP3, we confirmed the identity of the expanded lymph node population as FOXP3+ Treg cells and showed that this is accompanied by a comparable increase in the uterus of FOXP3+ Treg cells and expression of Foxp3 mRNA by Day 3.5 postcoitum. Seminal plasma was necessary for uterine Treg cell accumulation, as mating with seminal vesicle-deficient males failed to elicit an increase in uterine Treg cells. Furthermore seminal fluid induced expression of mRNA encoding the Treg chemokine CCL19 (MIP3beta), which acts through the CCR7 receptor to regulate Treg cell recruitment and retention in peripheral tissues. Glandular and luminal epithelial cells were identified as the major cellular origins of uterine CCL19, and exposure to both seminal plasma and sperm was required for maximum expression. Together, these results indicate that Treg cells accumulate in the uterus prior to embryo implantation and that seminal fluid is a key regulator of the uterine Treg cell population, operating by both increasing the pool of available Treg cells and promoting their CCL19-mediated recruitment from the circulation into the implantation site.

Preeclampsia is associated with lower percentages of regulatory T cells in maternal blood.

Objective: Immunological mechanisms are involved in the pathophysiology of preeclampsia. During pregnancy there is an increase in regulatory T (Treg) cells, which has an important role in regulating tolerance to the immunologically distinct fetus. We hypothesised that percentages of Treg cells are decreased in preeclamptic patients. Methods: Peripheral blood was obtained from 26 healthy pregnant controls and 18 preeclamptic patients. Treg cells were measured using flow-cytometry. Results: Women with pregnancies complicated by preeclampsia had significantly lower percentages of CD4+FOXP3+ Treg cells. Conclusion: We conclude that a deficiency of regulatory T cells may play a role in the pathophysiology of preeclampsia.

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.

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

OBJECTIVEnDuring 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.nnnSTUDY DESIGNnFirst-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.nnnRESULTSnSmoking 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.nnnCONCLUSIONnMaternal 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.

Immunomodulators to treat recurrent miscarriage

Recurrent miscarriage is a reproductive disorder affecting many couples. Although several factors are associated with recurrent miscarriage, in more than 50% of the cases the cause is unknown. Maladaptation of the maternal immune system is associated with recurrent miscarriage and could explain part of its pathophysiology. Modulating the maternal immune system toward pregnancy tolerance could benefit pregnancy outcome. Although there is a clear scientific rationale that modulating the maternal immune system could benefit recurrent miscarriage, only a few studies suggest possible beneficial effects of immune modulators as a therapy for recurrent miscarriage. Therapies skewing the maternal immune response to a tolerating regulatory T cell rich environment seem especially promising; however, more research is needed to find effective and safe maternal immune modulators for reproductive pathologies as recurrent miscarriage. Moreover, the possible side effects on maternal, fetal, and neonatal immune function are essentially unknown, and its elucidation is crucial before any possible therapeutic strategies could be clinically implemented.

Pregnancy persistently affects memory T cell populations.

Pregnancy is an immune challenge to the maternal immune system. The effects of pregnancy on maternal immunity and particularly on memory T cells during and after pregnancy are not fully known. This observational study aims to show the short term and the long term effects of pregnancy on the constitution, size and activation status of peripheral human memory T-lymphocyte populations. Effector memory (EM) and central memory (CM) T-lymphocytes were analyzed using flow cytometry of peripheral blood from 14 nulligravid, 12 primigravid and 15 parous women that were on average 18 months postpartum. The short term effects were shown by the significantly higher CD4+ EM cell and activated CD4+ memory cell proportions in primigravid women compared to nulligravid women. The persistent effects found in this study were the significantly higher proportions of CD4+ EM, CD4+ CM and activated memory T cells in parous women compared to nulligravid women. In contrast to CD4+ cells, activation status of CD8+ memory cells did not differ between the groups. This study shows that pregnancy persistently affects the pre-pregnancy CD4+ memory cell pool in human peripheral blood. During pregnancy, CD4+ T-lymphocytes might differentiate into EM cells followed by persistent higher proportions of CD4+ CM and EM cells postpartum. The persistent effects of pregnancy on memory T cells found in this study support the hypothesis that memory T cells are generated during pregnancy and that these cells could be involved in the lower complication risks in multiparous pregnancies in humans.

Lower FOXP3 mRNA Expression in First-Trimester Decidual Tissue from Uncomplicated Term Pregnancies with a Male Fetus

Pregnancies with a male fetus are associated with higher risks of pregnancy complications through maladaptation of the maternal immune system. The pathophysiology of this phenomenon is unknown. A possible pathway could be a fetal sex-dependent maternal immune response, since males have a Y chromosome encoding specific allogenic proteins, possibly contributing to a different response and higher complication risks. To analyze whether fetal sex affects mRNA expression of maternal immune genes in early pregnancy, real-time PCR quantification was performed in the decidual tissue from primigravid pregnancies (n = 20) between 10 and 12 weeks with uncomplicated term outcomes. Early-pregnancy decidual mRNA expression of the regulatory T-cell marker, FOXP3, was sixfold lower (p < 0.01) in pregnancies with a male fetus compared to pregnancies with a female fetus. Additionally, mRNA expression of IFNγ was sixfold (p < 0.05) lower in pregnancies with a male fetus. The present data imply maternal immunologic differences between pregnancies with male and female fetuses which could be involved in different pregnancy pathophysiologic outcomes. Moreover, this study indicates that researchers in reproductive immunology should always consider fetal sex bias.

Development of a core outcome set for immunomodulation in pregnancy (COSIMPREG): a protocol for a systematic review and Delphi study

Introduction To establish pregnancy, the maternal immune system must adapt to tolerate the semiallogenic fetus. Less than optimal adaptation of the maternal immune system during (early) pregnancy is implicated in several complications of pregnancy. The development of effective immune modulation interventions as preventive or therapeutic strategies for pregnancy complications holds promise. Several studies sought to evaluate the safety and effectiveness of various approaches. However, a limitation is the high variability in clinical and immune outcomes that are reported. We, therefore, aim to develop a core outcome set for application to studies of immune modulation in pregnancy (COSIMPREG). Methods and analysis We will use a stepwise approach to develop a COSIMPREG. First, we will perform a systematic review to identify reported outcomes. For this review, Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines will be followed. Second, we will use the Delphi method to develop a preliminary COSIMPREG. In three rounds, the outcomes of the systematic review will be scored. A panel comprising experts from relevant disciplines and diverse geographical locations will be assembled until a sufficient quality of the panel is reached. We will use predefined decision rules for outcomes. After each round outcomes, including scores, will be returned to the panel for further refinement. The outcomes not excluded after the third round will be taken to a consensus meeting. In this meeting, experts from all relevant disciplines will discuss and finalise the COSIMPREG. Ethics and dissemination For this study ethical approval is not required. The systematic review will be published in an appropriate open access reproductive immunology journal. Once the COSIMPREG is finalised, it will be published in an open access reproductive immunology journal, and disseminated at appropriate international meetings, as well as through relevant research and scientific societies. Experts involved in the Delphi study will be asked to give informed consent.