CD25+ FOXP3+ and CD4+ CD25+ cells distribution in decidual departments of women with severe and mild pre-eclampsia: Comparison with healthy pregnancies

A comprehensive review of the roles of T-cell immunity in preeclampsia

Preeclampsia (PE) is an obstetrical disorder that occurs after the 20th week of gestation. It is recognized as one of the "Great Obstetrical Syndromes" and principally contributes to maternal morbidity and mortality. PE has been associated with a range of immune disorders, including a preponderance of T helper (Th) 1 over Th2 cells and imbalanced levels of Th17 and T regulatory cells (Tregs). During pregnancy, T cells safeguard the placenta against immune rejection and aid embryo implantation while involved in pregnancy complications, such as PE. Promoting alloantigen-specific Treg cells is a potential preventive and therapeutic strategy for PE. However, ensuring the safety of mothers and infants is of the utmost importance since the risk-benefit ratio of reproductive and obstetric conditions differs significantly from that of immune diseases that pose a life-threatening risk. In this review, we systematically summarize the roles of T-cell immunity in the peripheral blood, reproductive tissues, and at the maternal-fetal interface of PE patients. Furthermore, the recent therapeutic approaches centered on targeting T cell immunity in PE are critically appraised.

Immunological regulation and the role of autophagy in preeclampsia

Autophagy is a bulk degradation system that maintains cellular homeostasis by producing energy and/or recycling excess proteins. During early placentation, extravillous trophoblasts invade the decidua and uterine myometrium, facing maternal immune cells, which participate in the immune suppression of paternal and fetal antigens. Regulatory T cells will likely increase in response to a specific antigen before and during early pregnancy. Insufficient expansion of antigen-specific Treg cells, which possess the same T cell receptor, is associated with the pathophysiology of preeclampsia, suggesting sterile systemic inflammation. Autophagy is involved in reducing inflammation through the degradation of inflammasomes and in the differentiation and function of regulatory T cells. Autophagy dysregulation induces protein aggregation in trophoblasts, resulting in placental dysfunction. In this review, we discuss the role of regulatory T cells in normal pregnancies. In addition, we discuss the association between autophagy and regulatory T cells in the development of preeclampsia based on reports on the role of autophagy in autoimmune diseases.

Long noncoding RNA WT1-AS regulates trophoblast proliferation, migration, and invasion via the microRNA-186-5p/CADM2 axis

This study aimed to determine the role of long noncoding RNA (lncRNA) WT1 antisense RNA (WT1-AS) in the occurrence and progression of preeclampsia (PE) and to determine the underlying molecular mechanisms. The associations between WT1-AS and microRNA (miR)-186-5p, and miR-186-5p and cell adhesion molecule 2 (CADM2) were predicted using StarBase software and verified via dual-luciferase assays. To explore the role of the human chorionic trophoblast line HTR-8/SVneo, gene (WT1-AS/miR-186-5p) gain/loss of function experiments were performed. Qualitative reverse transcription-polymerase chain reaction (RT-PCR) analysis was used to evaluate transfection efficiency. Cell proliferation, apoptosis, cell migration, and invasion were assessed using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), flow cytometry, and transwell analysis, respectively. Moreover, CADM2 protein expression was measured by western blotting. The results indicated that overexpression of WT1-AS inhibited cell viability, migration, and invasion, and induced apoptosis in HTR-8/SVneo cells. We observed that miR-186a-5p directly targeted WT1-AS, and miR-186a-5p knockdown reversed the effects of WT1-AS knockdown in HTR-8/SVneo cells. Binding sites were found between miR-186-5p and CADM2, and CADM2-overexpression reversed the influence of miR-186-5p mimic on HTR-8/SVneo cells. In summary, our findings demonstrated that lncRNA WT1-AS participates in PE by regulating the proliferation and invasion of placental trophoblasts, through the miR-186-5p/CADM2 axis.

Regulatory T Cells in Pregnancy Adverse Outcomes: A Systematic Review and Meta-Analysis

Background

Several studies report the role of Regulatory T-cells (Tregs) in the pathophysiology of pregnancy adverse outcomes.

Objective

The aim of this systematic review and meta-analysis was to determine whether there is an association between regulatory T cell levels and pregnancy adverse outcomes (PAOs), including pre-eclampsia and preterm birth (PTB).

Method

Literature searches were conducted in PubMed/MEDLINE, Embase, and Cochrane CENTRAL databases. Inclusion criteria were original articles (clinical trials, case-control studies and cohort studies) comparing Tregs, sampled from the decidua or maternal blood, in healthy pregnant women versus women with pre-eclampsia or PTB. The outcome was standardised mean difference (SMD) in Treg numbers. The tau-squared (Tau²), inconsistency index (I²), and chi-squared (χ²) test quantified heterogeneity among different studies. Analyses were performed in RevMan software V.5.4.0 for Mac using a random-effects model with outcome data reported with 95% confidence intervals (CI). This study was prospectively registered with PROSPERO (CRD42020205469). PRISMA guidelines were followed.

Results

From 4,085 unique studies identified, 36 were included in qualitative synthesis, and 34 were included in quantitative synthesis (meta-analysis). In total, there were 1,783 participants in these studies: healthy controls=964, pre-eclampsia=759, PTB=60. Thirty-two studies compared Tregs in healthy pregnant women and women with pre-eclampsia, and 30 of these sampled Tregs from peripheral blood showing significantly higher Treg numbers in healthy pregnancies (SMD; 1.46; 95% CI, 1.03-1.88; I²=92%). Four studies sampled Tregs from the maternal decidua showing higher Tregs in healthy pregnancies (SMD, 0.76; 95% CI, -0.13-1.65; I²=84%). No difference was found in the number of Tregs between early versus late pre-eclampsia (SMD,-1.17; 95% CI, -2.79-0.44; I²=94%). For PTB, two studies compared Tregs sampled from the peripheral blood with a tendency for higher Tregs in healthy pregnancies but this did not reach significance (SMD, 2.18; 95% CI, -1.34-5.70; I²=96%). Subcohort analysis using Treg analysis (flow cytometry vs. qPCR vs. immunofluorescence tissue staining) showed similar associations.

Conclusion

Lower Tregs in pregnancy, sampled from the maternal peripheral blood, are associated with pre-eclampsia. There is a need for further studies to confirm a relationship between low Tregs and PTB. As the precise mechanisms by which Tregs may mediate pre-eclampsia and PTB remain unclear, further fundamental research is necessary to elucidate the underlying processes and highlight the causative link.

Systematic Review Registration

PROSPERO, identifier CRD42020205469.

Decreased Expression of Cytotoxic Proteins in Decidual CD8+ T Cells in Preeclampsia

Simple Summary

CD8⁺ T cells are prominent decidual cells in the third trimester of healthy human pregnancy. They have a cytotoxic capacity which may control invasion of extravillous trophoblast and therefore affect placentation and play the role in development of preeclampsia. In this study, we examined the expression of CD8⁺ T cells in decidual tissue and peripheral blood of women with severe and mild preeclampsia in comparison to gestational age-matched healthy pregnancies. Additionally, the expression of cytotoxic proteins in CD8⁺ T cells was examined in order to specify their subpopulations.

Abstract

In our study, we aimed to establish expression of cytotoxic CD8⁺ T cells in the decidua basalis and the maternal peripheral blood (mPBL) of severe and mild preeclampsia (PE) and compare to healthy pregnancies. Decidual tissue and mPBL of 10 women with mild PE, 10 women with severe PE, and 20 age-matched healthy pregnancy controls were analyzed by double immunofluorescence and qPCR, respectively. By double immunofluorescence staining, we found a decreased total number of cells/mm² in decidua basalis of granulysin (GNLY)⁺ (p ˂ 0.0001), granzyme B (GzB)⁺(p ˂ 0.0001), GzB⁺CD8⁺(p ˂ 0.0001), perforin (PRF1)⁺ (p ˂ 0.0001), and PRF1⁺CD8⁺ (p ˂ 0.01) in the severe PE compared to control group. Additionally, we noticed the trend of lower mRNA expression for GNLY, granzyme A (GZMA), GzB, and PRF1 in CD8⁺ T cells of mPBL in mild and severe PE, with the latter marker statistically decreased in severe PE (p ˂ 0.001). Forkhead box P3 (FOXP3) mRNA in CD8⁺ T cells mPBL was increased in mild PE (p ˂ 0.001) compared to controls. In conclusion, severe PE is characterized by altered expression of cytotoxic CD8⁺ T cells in decidua and mPBL, suggesting their role in pathophysiology of PE and fetal-maternal immune tolerance.