Aberrant expressions of endometrial Id3 and CTLA-4 are associated with unexplained repeated implantation failure and recurrent miscarriage

Immune Checkpoints in Recurrent Pregnancy Loss: New Insights into a Detrimental and Elusive Disorder

Recurrent pregnancy loss (RPL) refers to two or more miscarriages before 20 weeks gestation. Its prevalence is 1-2%; its pathogenesis remains unexplained in more than 50% of cases, in which the cause is thought to be abnormal immune activity during placentation leading to a lack of pregnancy-induced immune tolerance. It is unknown whether immune activity is deranged in the endometrium of women with RPL. We studied the gene expression and the quantitative tissue protein levels of three immune checkpoints (CD276, which enhances cytotoxic T-cell activity, cytotoxic T-lymphocyte-associated antigen-4 [CTL-4], which reduces Th1 cytokine production, and lymphocyte activation gene-3 [LAG-3], which shows suppressive activity on Tregs and CD4+ T-cells) in endometrial samples from 27 women with unexplained RPL and in 29 women with dysfunctional uterine bleeding and previous uneventful pregnancies as controls. RNA isolation, real-time PCR, protein isolation, and ELISA were performed. CD276 gene expression and protein tissue levels were significantly lower in the endometrium of the RPL group than in the controls, whereas both CTL-4 and LAG-3 were significantly higher. This difference suggests defective endometrial immune regulation and overactivation of immune response in women with a history of RPL, at least in relation to controls with dysfunctional uterine bleeding and previous normal reproductive history.

Biology of cancer; from cellular and molecular mechanisms to developmental processes and adaptation

Cancer research has been largely focused on the cellular and molecular levels of investigation. Recent data show that not only the cell but also the extracellular matrix plays a major role in the progression of malignancy. In this way, the cells and the extracellular matrix create a specific local microenvironment that supports malignant development. At the same time, cancer implies a systemic evolution which is closely related to developmental processes and adaptation. Consequently, there is currently a real gap between the local investigation of cancer at the microenvironmental level, and the pathophysiological approach to cancer as a systemic disease. In fact, the cells and the matrix are not only complementary structures but also interdependent components that act synergistically. Such relationships lead to cell-matrix integration, a supracellular form of biological organization that supports tissue development. The emergence of this supracellular level of organization, as a structure, leads to the emergence of the supracellular control of proliferation, as a supracellular function. In humans, proliferation is generally involved in developmental processes and adaptation. These processes suppose a specific configuration at the systemic level, which generates high-order guidance for local supracellular control of proliferation. In conclusion, the supracellular control of proliferation act as an interface between the downstream level of cell division and differentiation, and upstream level of developmental processes and adaptation. Understanding these processes and their disorders is useful not only to complete the big picture of malignancy as a systemic disease, but also to open new treatment perspectives in the form of etiopathogenic (supracellular or informational) therapies.

Genomic instability and the link to infertility: A focus on microsatellites and genomic instability syndromes

Infertility is associated to multiple types of different genomic instabilities and is a genetic feature of genomic instability syndromes. While the mismatch repair machinery contributes to the maintenance of genome integrity, surprisingly its potential role in infertility is overlooked. Defects in mismatch repair mechanisms contribute to microsatellite instability and genomic instability syndromes, due to the inability to repair newly replicated DNA. This article reviews the literature to date to elucidate the contribution of microsatellite instability to genomic instability syndromes and infertility. The key findings presented reveal microsatellite instability is poorly researched in genomic instability syndromes and infertility.

Nobel Prize for immune checkpoint inhibitors, understanding the immunological switching between immunosuppression and autoimmunity

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are a revolutionary form of immunotherapy in cancer. However, the percentage of patients responding to therapy is relatively low, while adverse effects occur in a large number of patients. In addition, the therapeutic mechanisms of ICIs are not yet completely described.

AREAS COVERED

The initial view (articles published in PubMed, Scopus, Web of Science, etc.) was that ICIs increase tumor-specific immunity. Recent data (collected from the same databases) suggest that the ICIs pharmacotherapy actually extends beyond the topic of immune reactivity, including additional immune pathways, such as disrupting immunosuppression and increasing tumor-specific autoimmunity. Unfortunately, there is no clear delimitation between these specific autoimmune reactions that are therapeutically beneficial, and nonspecific autoimmune reactions/toxicity that can be extremely severe side effects.

EXPERT OPINION

Immune checkpoint mechanisms perform a non-selective immune regulation, maintaining a dynamic balance between immunosuppression and autoimmunity. By blocking these mechanisms, ICIs actually perform an immunological reset, decreasing immunosuppression and increasing tumor-specific immunity and predisposition to autoimmunity. The predisposition to autoimmunity induces both side effects and beneficial autoimmunity. Consequently, further studies are necessary to maximize the beneficial tumor-specific autoimmunity, while reducing the counterproductive effect of associated autoimmune toxicity.

Extracellular vesicles derived from M1 macrophages deliver miR-146a-5p and miR-146b-5p to suppress trophoblast migration and invasion by targeting TRAF6 in recurrent spontaneous abortion

Rationale: Emerging evidence demonstrates that insufficient migration and invasion of trophoblasts play critical roles in the pathogenesis of recurrent spontaneous abortion (RSA). Cell-to-cell communication at the maternal-fetal interface is essential to maintain the invasion and migration of trophoblasts. M1 macrophages, important immune cellular components at the maternal-fetal interface, have been reported to be elevated in decidua tissues from patients with RSA. Recent studies indicate that M1 macrophages modulate trophoblast biological behaviors; however, the underlying mechanisms remain poorly understood. Methods: Extracellular vesicles (EVs) were isolated from the supernatant of M1 macrophages inducted from THP-1 cells (M1-EVs) by ultracentrifugation, identified by transmission electron microscopy, nanoparticle tracking analysis, and western blotting, and their miRNA profile was characterized by miRNA sequencing. Scratch wound healing and transwell assays were used to investigate the effect of M1-EVs on trophoblast migration and invasion. RT-PCR, western blotting, and luciferase reporter assays were conducted to uncover the underlying mechanism. Finally, animal experiments were employed to explore the effect of M1-EVs on embryo absorption in mice. Results: M1 macrophages suppressed trophoblast EMT to reduce their migration and invasion abilities in vitro by secreting EVs. Through miRNA sequencing, miR-146a-5p and miR-146b-5p were identified as the most upregulated miRNAs in trophoblasts treated with M1-EVs. Further functional experiments showed that M1-EVs inhibited trophoblast migration and invasion by transferring miR-146a-5p and miR-146b-5p. Mechanistically, EV miR-146a-5p and miR-146b-5p inhibited EMT of trophoblasts by directly suppressing TNF receptor-associated factor 6 (TRAF6) expression at the post-transcriptional level. Furthermore, M1-EVs aggravated embryo absorption in mice. Clinically, expression of miR-146a-5p, miR-146b-5p, and TRAF6 were aberrant in placental villous tissues from patients with RSA, and negative correlations were found between miR-146a-5p/miR-146b-5p and TRAF6 expression levels. Conclusions: Our findings indicate that miR-146a-5p and miR-146b-5p derived from EVs play important roles in intercellular communication between M1 macrophages and trophoblasts, illuminating a novel mechanism in M1 macrophage regulation of trophoblasts and their role in RSA.

M2 macrophage-derived G-CSF promotes trophoblasts EMT, invasion and migration via activating PI3K/Akt/Erk1/2 pathway to mediate normal pregnancy

Trophoblasts are important parts of the placenta and exert vital roles in the maternal-foetal crosstalk, and sufficient trophoblasts migration and invasion is critical for embryo implantation and normal pregnancy. Macrophages, as the major components of decidual microenvironment at maternal-foetal interface, can interact with trophoblasts to participate in the regulation of normal pregnancy. Previously, our group have demonstrated that trophoblasts could induce macrophages polarization to M2 subtype by secreting interleukin-6 (IL-6); however, the understanding of macrophages regulating the migration and invasion of trophoblasts is limited. In the present study, we used the co-cultured model to further investigate the effects of macrophages on trophoblasts migration and invasion. Our results showed that co-culture with macrophages promoted epithelial-to-mesenchymal transition (EMT) of trophoblasts, thereby enhancing their migrative and invasive abilities. Further experiments revealed that M2 macrophage-derived G-CSF was a key factor, which promoted the EMT, migration and invasion of trophoblasts via activating PI3K/Akt/Erk1/2 signalling pathway. Clinically, G-CSF was highly expressed in placental villous tissues of normal pregnancy patients compared to patients with recurrent spontaneous abortion, and its expression level was significantly correlation with EMT markers. Taken together, these findings indicate the important role of M2 macrophages in regulating trophoblasts EMT, migration and invasion, contributing to a new insight in concerning the crosstalk between macrophages and trophoblasts in the establishment and maintenance of normal pregnancy.

New endometrial immune cell-based score (EI-score) for the prediction of implantation success for patients undergoing IVF/ICSI

PROBLEM

Limited evidence revealed whether endometrial immunological factors contribute to implantation success in the first-attempted in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) patients.

METHOD

The retrospective study was conducted among 139 eligible couples in the derivation cohort and 29 couples in the validation cohort. The expression of endometrial immune cell markers, including CD56 for natural killer cell, CD68 for pan-macrophage, CD163 for M2 macrophage, FOXP3 for regulatory T cell, CD1a for immature dendritic cell, CD83 for mature dendritic cell, CD8 for cytotoxic T cell and CD57 for mature NK and T cells were examined.

RESULTS

The profiles of endometrial immune cells showed significant difference between the pregnant and implantation failure group in the derivation cohort. Multivariate logistic regression analysis showed that the percentage of CD68⁺ pan-macrophage and CD163⁺ M2-macrophage, as well as the transfer strategy are associated with implantation outcomes (P < 0.001, P = 0.029, P = 0.004, respectively). The EI-score was constructed by a nomogram and validated by a clinical decision curve based on CD68⁺ pan-macrophage, CD163⁺ M2-macrophage, and the transfer strategy. The performance of the EI-score in the deviation cohort showed a c-index of 0.82 (95% CI 0.74-0.89), and the accuracy rate reached 79.3% in the validation cohort.

CONCLUSIONS

The endometrial immunological profiles in the mid-secretory phase is associated with implantation outcome in the first IVF/ICSI patients. EI-Score could help clinicians calculate the probability of implantation success via nomogram. Optimal decision point is determined by decision curve analysis and clinical impact curve, to aid in clinical decisions.

Trophoblast-derived IL-6 serves as an important factor for normal pregnancy by activating Stat3-mediated M2 macrophages polarization

Macrophages are major components of decidual microenvironment that play an important role in human implantation and placentation. Trophoblasts which migrate into the endometrium and interplay with decidual cells, have been reported to participate in the polarization of macrophages. However, the potential mechanisms of trophoblasts modulating M2 macrophages polarization still need further exploration. Herein, we used the co-cultured model to investigate the interaction between macrophages and trophoblasts. Our results illustrated that when co-cultured with trophoblasts, macrophages tended to polarize to M2-subtype, accompanied by increased expression of multiple M2 markers including CD206 and CCL18 mRNA expression and IL-10 and TGF-β protein level. Further experiments identified that trophoblast-derived IL-6, as the major contributor, promoted M2 macrophages polarization by activating Stat3 pathway. Moreover, activated M2 macrophages exerted a promoting role in the invasion and migration of trophoblasts in a feedback manner. Clinically, results from histology demonstrated that IL-6 expression in placental villous tissues was positive correlated with CD206-positive macrophage infiltration in decidua in normal pregnancy patients. Altogether, our findings indicate that trophoblasts induce M2 macrophages polarization via IL-6/Stat3 signal pathway, which in turn promote the invasion and migration of trophoblasts. These results provide insights into the crosstalk between macrophages and trophoblasts at maternal-fetal microenvironment in normal pregnancy.

The Role of B7 Family Molecules in Maternal-Fetal Immunity

Pregnancy is a complex but well-arranged process, and a healthy fetus requires immune privilege and surveillance in the presence of paternally derived antigens. Maternal and fetal cells interact at the maternal–fetal interface. The upregulation and downregulation of maternal immunity executed by the leukocyte population predominantly depend on the activity of decidual natural killer cells and trophoblasts and are further modulated by a series of duplex signals. The B7 family, which consists of B7-1, B7-2, B7-H1, B7-DC, B7-H2, B7-H3, B7-H4, B7-H5, BTNL2, B7-H6, and B7-H7, is one of the most characterized and widely distributed signaling molecule superfamilies and conducts both stimulatory and inhibitory signals through separate interactions. In particular, the roles of B7-1, B7-2, B7-H1, and their corresponding receptors in the progression of normal pregnancy and some pregnancy complications have been extensively studied. Together with the TCR–MHC complex, B7 and its receptors play a critical role in cell proliferation and cytokine secretion. Depending on this ligand–receptor crosstalk, the balance between the tolerance and rejection of the fetus is perfectly maintained. This review aims to provide an overview of the current knowledge of the B7 family and its functions in regulating maternal–fetal immunity through individual interactions.

Involvement of CXCL12/CXCR4 in the motility of human first-trimester endometrial epithelial cells through an autocrine mechanism by activating PI3K/AKT signaling

Background

CXCL12(chemokine ligand 12, CXCL12) and its receptors CXCR4 are widely expressed in maternal-fetal interface and plays an adjust role in materno-fetal dialogue and immune tolerance during early pregnancy. This study aimed to evaluate the role and mechanism of self-derived CXCL12 in modulating the functions of human first-trimester endometrial epithelial cells (EECs) and to identify the potential protein kinase signaling pathways involved in the CXCL12/CXCR4’s effect on EECs.

Methods

The expression of CXCL12 and CXCR4 in EECs was measured by using immunohistochemistry, immunofluorescence, real-time polymerase chain reaction and enzyme-linked immunosorbent assay. The effects of EEC-conditioned medium (EEC-CM) and recombinant human CXCL12 (rhCXCL12) on EEC migration and invasion in vitro were evaluated with migration and invasion assays. In-cell western blot analysis was used to examine the phosphorylation of protein kinase B (AKT), extracellular regulated protein kinases (ERKs) and phosphatidylinositol 3-kinase (PI3K) after CXCL12 treatment.

Results

CXCL12 and CXCR4 were both expressed in human first-trimester EECs at the mRNA and protein level. Both EEC-CM and rhCXCL12 significantly increased the migration and invasion of EECs (P < 0.05), which could be blocked by neutralizing antibodies against CXCR4 (P < 0.05) or CXCL12 (P < 0.05), respectively. CXCL12 activated both PI3K/AKT and ERK1/2 signaling and CXCR4 neutralizing antibody effectively reduced CXCL12-induced phosphorylation of AKT and ERK1/2. LY294002, a PI3K-AKT inhibitor, was able to reverse the promotive effect of EEC-CM or rhCXCL12 on EEC migration and invasion.

Conclusions

Human first-trimester EECs promoted their own migration and invasion through the autocrine mechanism with CXCL12/CXCR4 axis involvement by activating PI3K/AKT signaling. This study contributes to a better understanding of the epithelium function mediated by chemokine and chemokine receptor during normal pregnancy.

Female Unexplained Infertility: A Disease with Imbalanced Adaptive Immunity

Unexplained infertility (UI) among women consists of only 10-17% of infertile females. Unexplained or idiopathic infertility is a condition, in which couples are not able to conceive without any definite causes. The presence of the decidual immune system (innate or adaptive) is essential for a successful pregnancy and fertility that is mediated by T helper (Th) 1, Th2, Th17, T follicular helper, CD8+ CD28− T, and regulatory T cells, as well as autoantibodies such as antiphospholipid antibody, antithyroid antibody, antiovarian antibody, cytokines, and chemokines. Therefore, altered proportions or levels of the mentioned compartments of the adaptive immune system may cause pregnancy failure and infertility, especially in UI. Consequently, a deep understanding of immunological compartments in females with UI may help us to define the causes of this disease with regard to immunology. This review will discuss immunological factors, including cellular, molecular components, and transcription factors that are involved in the etiology of UI.

FasL on decidual macrophages mediates trophoblast apoptosis: A potential cause of recurrent miscarriage

Macrophages can induce Fas ligand (FasL)-mediated apoptosis, and the deregulation of apoptosis is known to be associated with recurrent miscarriage (RM). The aim of the present study was to investigate the possible involvement of FasL in macrophage-mediated trophoblast apoptosis and its potential role in RM. Human decidual and placental villous tissues were collected from 81 women (21 for the RM group, 26 for the spontaneous abortion group and 34 for the control group) at 7-9 weeks of gestation. The distribution changes of macrophages and the expression of FasL on macrophages were evaluated by immunohistochemical, immunofluorescence and western blot analyses. A macrophage and trophoblast co-culture model was used to determine the effects of FasL on the apoptosis of trophoblasts. The results indicated that CD86⁺ macrophage populations in decidual tissues were significantly increased, accompanied by reduced CD163⁺ macrophages in the abortion and RM groups. Furthermore, the distribution of CD68⁺ macrophages was also significantly altered in specimens from the abortion and RM groups, and they were observed to have infiltrated into the trophoblast cells. In addition, elevated expression of FasL on CD68⁺ and CD86⁺ macrophages in the decidua was observed in the spontaneous abortion and RM groups of patients, and FasL was demonstrated to mediate the induction of trophoblast apoptosis by macrophages in co-culture. These results indicate that the aberration of macrophage-induced FasL-mediated apoptosis may represent one of the causes of RM.