The metabolic characteristic of decidual immune cells and their unique properties in pregnancy loss

Perturbations of the endometrial immune microenvironment in endometriosis and adenomyosis: their impact on reproduction and pregnancy

The impact of endometriosis and adenomyosis on reproduction and pregnancy is significant, with both conditions linked to increased rates of infertility, poor ovarian function in women with endometriosis, and elevated pregnancy complications in those with adenomyosis. However, the underlying mechanisms remain largely unclear. Both conditions share a similar pathophysiological process characterized by the growth of ectopic endometrium, which may originate from the eutopic endometrium. Notably, surgical removal of ectopic lesions does not appear to significantly improve reproductive and pregnancy outcomes, further underscoring the importance of eutopic endometrium in these adverse effects. Emerging evidence indicates substantial differences in endometrial NK cells, macrophages, and T cells, leading to inflammatory responses in women with endometriosis and adenomyosis. These alterations may contribute not only to disease progression but also to defective endometrial receptivity, insufficient angiogenesis remodeling, impaired maternal-fetal immune tolerance, and poor placentation, thereby influencing embryo implantation and pregnancy maintenance. This provides an immunological perspective to explain the higher rates of infertility and pregnancy complications observed in affected women. Therefore, we systematically review the alterations in endometrial immune cells in women with endometriosis and adenomyosis compared to healthy controls, exploring the potential impacts of these changes on reproduction and pregnancy. This review aims to lay the groundwork for future studies on the immunopathogenesis associated with endometriosis and adenomyosis-related reproductive failure and pregnancy complications, shedding lights on the development of immunotherapeutic strategies to mitigate these adverse impacts in affected women.

CD36-mediated arachidonic acid influx from decidual stromal cells increases inflammatory macrophages in miscarriage

Spontaneous abortion is associated with aberrant lipid metabolism, but the underlying mechanisms remain unclear. Here, we show that lipids are accumulated in decidual stromal cells (DSCs) and macrophages (dMφs) in women with miscarriage and mouse abortion-prone models. Moreover, we show that excessive lipids from DSCs are transferred to dMφs via a CD36-dependent mechanism that induces inflammation in dMφs. In particular, DSC-derived arachidonic acid (AA) is internalized by dMφs via CD36, which activates cyclooxygenase 2-dependent prostaglandin E2 production and interleukin (IL)-1β expression. In mice, AA injection induces miscarriage, whereas conditional knockout of Cd36 in dMφs ameliorates AA-induced embryo loss. Additionally, DSC-derived prolactin (PRL) inhibits CD36-mediated lipid intake in dMφs, and PRL administration reduces embryo loss in pregnant mice treated with CD36+ Mφs. Our findings reveal a critical interplay between DSCs and dMφs in dysregulated lipid metabolism that may contribute to miscarriage, in which PRL may be harnessed as a therapeutic agent.

Ralationship between polymorphisms and diplotypes of HLA-G 3'UTR and fetuses with abnormal chromosomes or unexplained pregnancy loss (UPL)

OBJECTIVES

Human leukocyte antigen G (HLA-G) plays a crucial role in pregnancy. Pregnancy loss (PL) is caused by a variety of causes, such as fetal chromosomal abnormalities, maternal hypertension and diabetes, immune causes, spontaneous immune diseases, infections, unknown causes, etc. This study reports on the association of fetal HLA-G 3'UTR polymorphisms and diplotypes with chromosomally abnormal fetuses (CAF) or unexplained pregnancy loss (UPL).

METHODS

A total of 552 specimens were collected and grouped by next-generation sequencing technology (NGS) and fetal survival: UPL (112 cases), CAF (170 cases) and control (258 cases). The polymorphisms of HLA-G 3'UTR in all samples were detected by Sanger sequencing. The genotypes, haplotypes and diplotypes of HLA-G 3'UTR were analyzed. The classification and regression tree (CART) analysis was used to evaluate the role of HLA-G diplotypes in predicting fetal outcomes. The correlations between CAF or UPL and maternal age, paternal age, times of miscarrage, times of delivery were analyzed by logistic regression.

RESULTS

The frequencies of HLA-G + 2960del/del and + 3035CC genotypes were remarkablly increased in CAF than those in control group. The frequencies of HLA-G + 2960ins/del, + 3010CC, + 3035TC, + 3142GG, + 3187AA in CAF were significantly lower than those in normal fetuses. Through genetic models and logistic regression analysis, the dominant model of HLA-G 3'UTR genotypes [such as + 2960 (OR = 1.27, 95% CI = 1.05-1.54, p = 0.016), + 3010 (OR = 0.78, 95% CI = 0.63-0.97, p = 0.026), + 3035 (OR = 1.22, 95% CI = 1.00-1.49, p = 0.047), + 3142 (OR = 0.76, 95% CI = 0.62-0.95, p = 0.014) and + 3187 (OR = 0.80, 95% CI = 0.65-0.99, p = 0.041)] were dramatically associated with CAF. However, the frequencies of HLA-G + 3010GC, + 3142GC and + 3187AG in fetuses with UPL were memorably decreased than those in normal fetuses. No significant difference was found in the frequencies of HLA-G haplotypes in all groups. However, the frequency of UTR-1 positive specimens in CAF was significantly higher than that in UPL and control group. At the same time, the frequency of UTR-1/UTR-3 diplotypes in CAF was observably higher than that in UPL and control group, while the UTR-1/UTR-7 frequency in UPL was signally lower than that in control group. Multivariate logistic regression analysis indicated that positive HLA-G UTR-1 (OR = 1.8, 95% CI = 1.16-2.81, p = 0.009), times of abortion (OR = 1.23, 95% CI = 1.02-1.50, p = 0.035), and times of delivery (OR = 0.31, 95% CI = 0.20-0.48, p < 0.001) were correlated with CAF.

CONCLUSIONS

This study suggests that HLA-G 3'UTR polymorphisms and diplotypes play an important role in the process of successful pregnancy of the embryos with abnormal chromosomes after fertilization. At the same time, Different alleles or diplotypes also affect the development of embryos with UPL.

Impact of Vitamin D deficiency on immunological and metabolic responses in women with recurrent pregnancy loss: focus on VDBP/HLA-G1/CTLA-4/ENTPD1/adenosine-fetal-maternal conflict crosstalk

BACKGROUND AND AIM

Recurrent pregnancy loss (RPL), also known as recurrent implantation failure (RIF), is a distressing condition affecting women characterized by two or more consecutive miscarriages or the inability to carry a pregnancy beyond 20 weeks. Immunological factors and genetic variations, particularly in Vit D Binding Protein (VDBP), have gained attention as potential contributors to RPL. This study aimed to provide insight into the immunological, genetic, and metabolic networks underlying RPL, placing a particular emphasis on the interactions between VDBP, HLA-G1, CTLA-4, ENTPD1, and adenosine-fetal-maternal conflict crosstalk.

METHODS

A retrospective study included 198 women with three or more consecutive spontaneous abortions. Exclusion criteria comprised uterine abnormalities, endocrine disorders, parental chromosomal abnormalities, infectious factors, autoimmune diseases, or connective tissue diseases. Immunological interplay was investigated in 162 female participants, divided into two groups based on their Vit D levels: normal Vit D-RPL and low Vit D-RPL. Various laboratory techniques were employed, including LC/MS/MS for Vit D measurement, ELISA for protein detection, flow cytometry for immune function analysis, and molecular docking for protein-ligand interaction assessment.

RESULTS

General characteristics between groups were significant regarding Vit D and glucose levels. Low Vit D levels were associated with decreased NK cell activity and downregulation of HLA-G1 and HLA-G5 proteins, while CTLA-4 revealed upregulation. VDBP was significantly downregulated in the low Vit D group. Our findings highlight the intricate relationship between Vit D status and adenosine metabolism by the downregulation of SGLT1, and NT5E, key components of adenosine metabolism, suggests that Vit D deficiency may disrupt the regulation of adenosine levels, leading to an impaired reproductive outcome. HNF1β, a negative regulator of VDBP, was upregulated, while HNF1α, a positive regulator, was downregulated in low Vit D women after RPL. Molecular docking analysis revealed crucial residues involved in the interaction between Vit D and HNF1β.

CONCLUSION

Collectively, these findings underscore the importance of Vit D in modulating immune function and molecular pathways relevant to pregnancy maintenance, highlighting the need for further research to elucidate the mechanisms and potential therapeutic interventions for improving pregnancy outcomes in individuals with Vit D deficiency and RPL.

A Hypoxia-Decidual Macrophage Regulatory Axis in Normal Pregnancy and Spontaneous Miscarriage

The significance of hypoxia at the maternal-fetal interface is proven to be self-explanatory in the context of pregnancy. During the first trimester, low oxygen conditions play a crucial role in processes such as angiogenesis, trophoblast invasion and differentiation, and immune regulation. Recently, there has been increasing research on decidual macrophages, which contribute to the maintenance of immune tolerance, placental and fetal vascular development, and spiral artery remodeling, to investigate the effects of hypoxia on their biological behaviors. On these grounds, this review describes the dynamic changes in oxygen levels at the maternal-fetal interface throughout gestation, summarizing current knowledge on how the hypoxic environment sustains a successful pregnancy by regulating retention, differentiation and efferocytosis of decidual macrophages. Additionally, we explore the relationship between spontaneous miscarriages and an abnormal hypoxia-macrophage axis, shedding light on the underlying mechanisms. However, further studies are essential to elucidate these pathways in greater detail and to develop targeted interventions that could improve pregnancy outcomes.

Evaluation of conical 9 well dish on bovine oocyte maturation and subsequent embryonic development

The Conical 9 well dish (C9 well dish) is characterized by a decreasing cross-sectional area towards the base. This design was hypothesized to enhance embryonic development by emulating the in vivo physical environment through density modulation. Comparative analyses revealed no significant difference in nuclear maturation rates between the C9 well dish and the 5-well dish. Reactive oxygen species (ROS) generation was lower in the C9 well dish compared to the 5-well dish; however, this difference was not statistically significant. On the second day of in vitro culture, the cleavage rate in the C9 well dish was 4.66% higher, although not statistically significant, and the rates of blastocyst development were similar across both dishes. No significant differences were observed in the intracellular levels of glutathione (GSH) and ROS, as well as in the total cell number within the blastocysts between the dish types. The expression of mitogen-related factors, TGFα and IGF-1, in the blastocysts was consistent between the dishes. However, PDGFβ expression was significantly lower in the C9 well dish compared to the 35 mm petri dish. Similarly, the expression of the apoptosis factor Bax/Bcl2l2 showed no significant differences between the two dishes. Despite the marked difference in PDGFβ expression, its impact on blastocyst formation appeared negligible. The study also confirmed the feasibility of culturing a small number of oocytes per donor, collected via Ovum Pick-Up (OPU), with reduced volumes of culture medium and mineral oil, thus offering economic advantages. In conclusion, the present study indicates that the C9 well dish is effective for in vitro development of a small quantity of oocytes and embryos, presenting it as a viable alternative to traditional cell culture dishes.

Recombinant humanized type I collagen remodels decidual immune microenvironment at maternal-fetal interface by modulating Th17/Treg imbalance

Disruption of the extracellular matrix and dysregulation of the balance between Th17 and regulatory T cells are recognized as risk factors for recurrent spontaneous abortion (RSA). However, the interaction between matrix components and the Th17/Treg axis remains poorly elucidated. The result of this study revealed that the absence of type I collagen in the decidua is linked to Th17/Treg imbalance in RSA. Furthermore, we discovered that biomaterial recombinant humanized type I collagen (rhCOLI) promoted T cell differentiation into Tregs by inhibition the Notch1/Hes1 signaling pathway and enhanced the immunosuppressive function of Tregs, as indicated by increased secretion level of IL-10 and TGF-β. Importantly, this study is the first to demonstrate that rhCOLI can modulate the Th17/Treg imbalance, reduce embryo resorption rates, reshape the immune microenvironment at the maternal-fetal interface, and improve fertility in an RSA mouse model. Collectively, these findings suggest that type I collagen deficiency may contribute to, rather than result from, RSA, and propose a potential intervention for RSA using rhCOLI.

Identification of circRNA Expression Profile and Potential Systemic Immune Imbalance Modulation in Premature Rupture of Membranes

Premature rupture of membrane (PROM) refers to the rupture of membranes before the onset of labor which increases the risk of perinatal morbidity and mortality. Recently, circular RNAs (circRNAs) have emerged as promising regulators of diverse diseases. However, the circRNA expression profiles and potential circRNA-miRNA-mRNA regulatory mechanisms in PROM remain enigmatic. In this study, we displayed the expression profiles of circRNAs and mRNAs in plasma and fetal membranes of PROM and normal control (NC) groups based on circRNA microarray, the Gene Expression Omnibus database, and NCBI's Sequence Read Archive. A total of 1,459 differentially expressed circRNAs (DECs) in PROM were identified, with 406 upregulated and 1,053 downregulated. Then, we constructed the circRNA-miRNA-mRNA network in PROM, encompassing 22 circRNA-miRNA pairs and 128 miRNA-mRNA pairs. Based on the analysis of gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and gene set enrichment analysis (GSEA), DECs were implicated in immune-related pathways, with certain alterations persisting even postpartum. Notably, 11 host genes shared by DECs of fetal membrane tissue and prenatal plasma in PROM were significantly implicated in inflammatory processes and extracellular matrix regulation. Our results suggest that structurally stable circRNAs may predispose to PROM by mediating systemic immune imbalances, including peripheral leukocyte disorganization, local immune imbalance at the maternal-fetal interface, and local collagen disruption. This is the first time to decipher a landscape on circRNAs of PROM, reveals the pathogenic cause of PROM from the perspective of circRNA, and opens up a new direction for the diagnosis and treatment of PROM.

Macrophage plasticity and function in cancer and pregnancy

As the soil of life, the composition and shaping process of the immune microenvironment of the uterus is worth exploring. Macrophages, indispensable constituents of the innate immune system, are essential mediators of inflammation and tissue remodeling as well. Recent insights into the heterogeneity of macrophage subpopulations have renewed interest in their functional diversity in both physiological and pathological settings. Macrophages display remarkable plasticity and switch from one phenotype to another. Intrinsic plasticity enables tissue macrophages to perform a variety of functions in response to changing tissue contexts, such as cancer and pregnancy. The remarkable diversity and plasticity make macrophages particularly intriguing cells given their dichotomous role in either attacking or protecting tumors and semi-allogeneic fetuses, which of both are characterized functionally by immunomodulation and neovascularization. Here, we reviewed and compared novel perspectives on macrophage biology of these two settings, including origin, phenotype, differentiation, and essential roles in corresponding microenvironments, as informed by recent studies on the heterogeneity of macrophage identity and function, as well as their mechanisms that might offer opportunities for new therapeutic strategies on malignancy and pregnancy complications.

Glycolysis: A fork in the path of normal and pathological pregnancy

Glucose metabolism is vital to the survival of living organisms. Since the discovery of the Warburg effect in the 1920s, glycolysis has become a major research area in the field of metabolism. Glycolysis has been extensively studied in the field of cancer and is considered as a promising therapeutic target. However, research on the role of glycolysis in pregnancy is limited. Recent evidence suggests that blastocysts, trophoblasts, decidua, and tumors all acquire metabolic energy at specific stages in a highly similar manner. Glycolysis, carefully controlled throughout pregnancy, maintains a dynamic and coordinated state, so as to maintain the homeostasis of the maternal-fetal interface and ensure normal gestation. In the present review, we investigate metabolic remodeling and the selective propensity of the embryo and placenta for glycolysis. We then address dysregulated glycolysis that occurs in the cellular interactive network at the maternal-fetal interface in miscarriage, preeclampsia, fetal growth restriction, and gestational diabetes mellitus. We provide new insights into the field of maternal-fetal medicine from a metabolic perspective, thus revealing the mystery of human pregnancy.

Unique metabolism and protein expression signature in human decidual NK cells

Human decidual natural killer (dNK) cells are a unique type of tissue-resident NK cells at the maternal-fetal interface. dNK cells are likely to have pivotal roles during pregnancy, including in maternal-fetal immune tolerance, trophoblast invasion, and fetal development. However, detailed insights into these cells are still lacking. In this study, we performed metabolomic and proteomic analyses on human NK cells derived from decidua and peripheral blood. We found that 77 metabolites were significantly changed in dNK cells. Notably, compared to peripheral blood NK (pNK) cells, 29 metabolites involved in glycerophospholipid and glutathione metabolism were significantly decreased in dNK cells. Moreover, we found that 394 proteins were differentially expressed in dNK cells. Pathway analyses and network enrichment analyses identified 110 differentially expressed proteins involved in focal adhesion, cytoskeleton remodeling, oxidoreductase activity, and fatty acid metabolism in dNK cells. The integrated proteomic and metabolomic analyses revealed significant downregulation in glutathione metabolism in dNK cells compared to pNK cells. Our data indicate that human dNK cells have unique metabolism and protein-expression features, likely regulating their function in pregnancy and immunity.