The Contribution of Macrophages to Normal and Pathological Pregnancies

Regional Analysis of the Immune Microenvironment in Human Endometrium

PROBLEM

Endometrial immune cells are essential for maintaining homeostasis and the endometrial receptivity to embryo implantation. Understanding regional variations in endometrial immune cell populations is crucial for comprehending normal endometrial function and the pathophysiology of endometrial disorders. Despite previous studies focusing on the overall immune cell composition and function in the endometrium, regional variations in premenopausal women remain unclear.

METHOD OF STUDY

Endometrial biopsies were obtained from four regions (anterior, posterior, left lateral, and right lateral) of premenopausal women undergoing hysteroscopy with no abnormalities. A 15-color human endometrial immune cell-focused flow cytometry panel was used for analysis. High-dimensional flow cytometry combined with a clustering algorithm was employed to unravel the complexity of endometrial immune cells. Additionally, multiplex immunofluorescent was performed for further validation.

RESULTS

Our findings revealed no significant variation in the distribution and abundance of immune cells across different regions under normal conditions during the proliferative phase. Each region harbored similar immune cell subtypes, indicating a consistent immune microenvironment. However, when comparing normal regions to areas with focal hemorrhage, significant differences were observed. An increase in CD8+ T cells highlights the impact of localized abnormalities on the immune microenvironment.

CONCLUSIONS

Our study demonstrates that the endometrial immune cell landscape is consistent across different anatomical regions during the proliferative phase in premenopausal women. This finding has important implications for understanding normal endometrial function and the pathophysiology of endometrial disorders.

Transamniotic Stem Cell Therapy Modulates Uterine Natural Killer Cell Activity in the Hypoxia Model of Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) pathophysiology is driven by abnormal uterine natural killer cell (uNK) activity leading to placental dysfunction. Transamniotic stem cell therapy (TRASCET) with mesenchymal stem cells (MSCs) can improve experimental IUGR by mechanisms not fully understood. We sought to examine TRASCET's effects in downstream products of uNKs in a model of IUGR: 15 Sprague-Dawley dams were exposed to alternating hypoxia (10.5% O2) from gestational day 15 (E15) until term (E21). Their fetuses (n = 189) were divided into four groups. One group remained untreated (n = 52), whereas three groups received volume-matched intraamniotic injections of either saline (sham, n = 44) or a suspension of amniotic fluid-derived MSCs, either in their native state (TRASCET, n = 50) or "primed" to an enhanced antiinflammatory phenotype (TRASCET-Primed, n = 43). Normal fetuses served as controls (n = 33). At term, various analyses were performed, including ELISA for surrogates of placental inflammation and uNK activity. Statistical comparisons included Bonferroni-adjusted criterion. Overall survival from hypoxia was 74% (140/189). Placental efficiency was lower in untreated and sham but normalized in both TRASCET groups (P < 0.01-0.47). Interleukin-17, a stimulator of uNKs, was elevated from normal in all groups (P < 0.01 for all). Interferon-gamma, released from activated uNKs, was elevated in all groups except sham but lower than the untreated in both TRASCET groups (P ≤ 0.01-0.06). Tumor necrosis factor-alpha, also produced by uNKs, was elevated in untreated and sham (P < 0.01 for both), but normalized by TRASCET (P = 0.05) and even lowered from normal in TRASCET-Primed (P < 0.01). Vascular endothelial growth factor, also released by uNKs, was elevated in untreated and sham but lower than normal in both TRASCET groups (P < 0.01 for all). We conclude that TRASCET with MSCs modulates the activity of placental uNKs in experimental IUGR, with distinct effects on their downstream products. This mechanistic insight may inform the development of novel strategies for the management of this disease.

Innate and adaptive immune dysregulation in women with recurrent implantation failure

Recurrent implantation failure (RIF) is a condition where a woman fails to obtain pregnancy after multiple embryo transfer cycles, even with superior-quality blastocysts. There are various factors that can contribute to RIF, including immunologic disturbances. The immune system is extremely important during pregnancy. Immune cells such as T cells, B cells, natural killer (NK) cells, and macrophages (MQ) are present in the female reproductive tract and are accountable for regulating the immune response to invading pathogens and maintaining tissue homeostasis. Dysregulation of these immune cells can lead to inflammation, which can impair fertility. One of the most common immunological disturbances observed in RIF is an altered Th1/Th2 ratio, along with changes in NK cell and macrophage numbers. In addition, the presence of some antibodies, such as anti-ovarian antibodies, can also contribute to RIF. Interleukins have been implicated in the development of an inflammatory response that can interfere with successful embryo implantation. As a result, a comprehensive understanding of immunological compartments in RIF women could assist us in determining the immunological origins of this disease. We will discuss immunological factors that might contribute to RIF etiology, including cellular and molecular components.

Engineering antigen-presenting cells for immunotherapy of autoimmunity

Autoimmune diseases are burdensome conditions that affect a significant fraction of the global population. The hallmark of autoimmune disease is a host's immune system being licensed to attack its tissues based on specific antigens. There are no cures for autoimmune diseases. The current clinical standard for treating autoimmune diseases is the administration of immunosuppressants, which weaken the immune system and reduce auto-inflammatory responses. However, people living with autoimmune diseases are subject to toxicity, fail to mount a sufficient immune response to protect against pathogens, and are more likely to develop infections. Therefore, there is a concerted effort to develop more effective means of targeting immunomodulatory therapies to antigen-presenting cells, which are involved in modulating the immune responses to specific antigens. In this review, we highlight approaches that are currently in development to target antigen-presenting cells and improve therapeutic outcomes in autoimmune diseases.

Decidual macrophages and Hofbauer cells in fetal growth restriction

Placental macrophages, which include maternal decidual macrophages and fetal Hofbauer cells, display a high degree of phenotypical and functional plasticity. This provides these macrophages with a key role in immunologically driven events in pregnancy like host defense, establishing and maintaining maternal-fetal tolerance. Moreover, placental macrophages have an important role in placental development, including implantation of the conceptus and remodeling of the intrauterine vasculature. To facilitate these processes, it is crucial that placental macrophages adapt accordingly to the needs of each phase of pregnancy. Dysregulated functionalities of placental macrophages are related to placental malfunctioning and have been associated with several adverse pregnancy outcomes. Although fetal growth restriction is specifically associated with placental insufficiency, knowledge on the role of macrophages in fetal growth restriction remains limited. This review provides an overview of the distinct functionalities of decidual macrophages and Hofbauer cells in each trimester of a healthy pregnancy and aims to elucidate the mechanisms by which placental macrophages could be involved in the pathogenesis of fetal growth restriction. Additionally, potential immune targeted therapies for fetal growth restriction are discussed.

Developmental Programming of the Fetal Immune System by Maternal Western-Style Diet: Mechanisms and Implications for Disease Pathways in the Offspring

Maternal obesity and over/undernutrition can have a long-lasting impact on offspring health during critical periods in the first 1000 days of life. Children born to mothers with obesity have reduced immune responses to stimuli which increase susceptibility to infections. Recently, maternal western-style diets (WSDs), high in fat and simple sugars, have been associated with skewing neonatal immune cell development, and recent evidence suggests that dysregulation of innate immunity in early life has long-term consequences on metabolic diseases and behavioral disorders in later life. Several factors contribute to abnormal innate immune tolerance or trained immunity, including changes in gut microbiota, metabolites, and epigenetic modifications. Critical knowledge gaps remain regarding the mechanisms whereby these factors impact fetal and postnatal immune cell development, especially in precursor stem cells in bone marrow and fetal liver. Components of the maternal microbiota that are transferred from mothers consuming a WSD to their offspring are understudied and identifying cause and effect on neonatal innate and adaptive immune development needs to be refined. Tools including single-cell RNA-sequencing, epigenetic analysis, and spatial location of specific immune cells in liver and bone marrow are critical for understanding immune system programming. Considering the vital role immune function plays in offspring health, it will be important to understand how maternal diets can control developmental programming of innate and adaptive immunity.

Establishment and comparison of human term placenta-derived trophoblast cells†

Research on the biology of fetal-maternal barriers has been limited by access to physiologically relevant cells, including trophoblast cells. In this study, we describe the development of a human term placenta-derived cytotrophoblast immortalized cell line (hPTCCTB) derived from the basal plate. Human-term placenta-derived cytotrophoblast immortalized cell line cells are comparable to their primary cells of origin in terms of morphology, marker expression, and functional responses. We demonstrate that these can transform into syncytiotrophoblast and extravillous trophoblasts. We also compared the hPTCCTB cells to immortalized chorionic trophoblasts (hFM-CTC), trophoblasts of the chorionic plate, and BeWo cells, choriocarcinoma cell lines of conventional use. Human-term placenta-derived cytotrophoblast immortalized cell line and hFM-CTCs displayed more similarity to each other than to BeWos, but these differ in syncytialization ability. Overall, this study (1) demonstrates that the immortalized hPTCCTB generated are cells of higher physiological relevance and (2) provides a look into the distinction between the spatially distinct placental and fetal barrier trophoblasts cells, hPTCCTB and hFM-CTC, respectively.

Monocyte immunometabolic reprogramming in human pregnancy: contribution of trophoblast cells

Immunometabolism research is uncovering the relationship between metabolic features and immune cell functions in physiological and pathological conditions. Normal pregnancy entails a fine immune and metabolic regulation of the maternal-fetal interaction to assist the energetic demands of the fetus with immune homeostasis maintenance. Here, we determined the immunometabolic status of monocytes of pregnant women compared with nonpregnant controls and its impact on monocyte anti-inflammatory functions such as efferocytosis. Monocytes from pregnant women (16-20 wk) and nonpregnant age-matched controls were studied. Single cell-based metabolic assays using freshly isolated monocytes from both groups were carried out in parallel with functional assays ex vivo to evaluate monocyte efferocytic capacity. On the other hand, various in vitro metabolic assays with human monocytes or monocyte-derived macrophages were designed to explore the effect of trophoblast cells in the profiles observed. We found that pregnancy alters monocyte metabolism and function. An increased glucose dependency and enhanced efferocytosis were detected in monocytes from pregnant women at resting states, compared with nonpregnant controls. Furthermore, monocytes display a reduced glycolytic response when stimulated with lipopolysaccharide (LPS). The metabolic profiling of monocytes at this stage of pregnancy was comparable with the immunometabolic phenotypes of human monocytes treated in vitro with human first trimester trophoblast cell conditioned media. These findings suggest that immunometabolic mechanisms are involved in the functional shaping of monocytes during pregnancy with a contribution of trophoblast cells. Results provide new clues for future hypotheses regarding pregnancies complicated by metabolic disorders.NEW & NOTEWORTHY Immunometabolism stands as a novel perspective to understand the complex regulation of the immune response and to provide small molecule-based therapies. By applying this approach to study monocytes during pregnancy, we found that these cells have a unique activation pattern. They rely more on glycolysis and show increased efferocytosis/IL-10 production, but they do not have the typical proinflammatory responses. We also present evidence that trophoblast cells can shape monocytes into this distinct immunometabolic profile.

Going Full TeRM: The Seminal Role of Tissue-Resident Macrophages in Organ Remodeling during Pregnancy and Lactation

During pregnancy and lactation, the uterus and mammary glands undergo remarkable structural changes to perform their critical reproductive functions before reverting to their original dormant state upon childbirth and weaning, respectively. Underlying this incredible plasticity are complex remodeling processes that rely on coordinated decisions at both the cellular and tissue-subunit levels. With their exceptional versatility, tissue-resident macrophages play a variety of supporting roles in these organs during each stage of development, ranging from maintaining immune homeostasis to facilitating tissue remodeling, although much remains to be discovered about the identity and regulation of individual macrophage subsets. In this study, we review the increasingly appreciated contributions of these immune cells to the reproductive process and speculate on future lines of inquiry. Deepening our understanding of their interactions with the parenchymal or stromal populations in their respective niches may reveal new strategies to ameliorate complications in pregnancy and breastfeeding, thereby improving maternal health and well-being.

Extra villous trophoblast-derived PDL1 can ameliorate macrophage inflammation and promote immune adaptation associated with preeclampsia

INTRODUCTION

Severe preeclampsia (sPE) is a systemic syndrome that may originate from chronic inflammation. Maintaining maternal-fetal hemostasis by the co-inhibitory molecule programmed death ligand 1 (PDL1) can be favorable for ameliorating inflammation from immune cells. Apart from programmed death 1 (PD1) expression, decidual macrophages (dMs) produce inflammatory cytokines, in response to cells which express PDL1. However, strong evidence is lacking regarding whether the PDL1/PD1 interaction between trophoblasts and decidual macrophages affects inflammation during sPE development.

METHODS

To determine whether the trophoblast-macrophage crosstalk via the PDL1/PD1 axis modulates the inflammatory response in sPE-like conditions, at first, maternal-fetal tissues from sPE and normal patients were collected, and the PDL1/PD1 distribution was analyzed by Western blot, immunohistochemistry/ immunofluorescence and flow cytometry. Next, a coculture system was established and flow cytometry was used to identify how PDL1 was involved in macrophage-related inflammation under hypoxic stress. Transcriptional analysis was performed to clarify the inflammation-associated pathway induced by the PDL1/PD1 interaction. Finally, the Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) mouse model was used to examine the effect of PDL1 on macrophage-related inflammation by measuring PE-like symptoms.

RESULTS

In maternal-fetal tissue from sPE patients, placental extravillous trophoblasts (EVTs) and dMs had a surprisingly increase of PDL1 and PD1 expression, respectively, accompanied by a higher percentage of CD68 +CD86 + dMs. In vitro experiments showed that trophoblast-derived PDL1 under hypoxia interacted with PD1 on CD14 +CD80 +macrophages, leading to suppression of inflammation through the TNFα-p38/NFκB pathway. Accordingly, the PE-like mouse model showed a reversal of PE-like symptoms and a reduced F4/80 + CD86 + macrophage percentage in the uterus in response to recombinant PDL1 protein administration, indicating the protective effect of PDL1.

DISCUSSION

Our results initially explained an immunological adaptation of trophoblasts under placental hypoxia, although this protection was insufficient. Our findings suggest the possible capacity of modulating PDL1 expression as a potential therapeutic strategy to target the inflammatory response in sPE.

Nested Selves: Self-Organization and Shared Markov Blankets in Prenatal Development in Humans

The immune system is a central component of organismic function in humans. This paper addresses self-organization of biological systems in relation to-and nested within-other biological systems in pregnancy. Pregnancy constitutes a fundamental state for human embodiment and a key step in the evolution and conservation of our species. While not all humans can be pregnant, our initial state of emerging and growing within another person's body is universal. Hence, the pregnant state does not concern some individuals but all individuals. Indeed, the hierarchical relationship in pregnancy reflects an even earlier autopoietic process in the embryo by which the number of individuals in a single blastoderm is dynamically determined by cell- interactions. The relationship and the interactions between the two self-organizing systems during pregnancy may play a pivotal role in understanding the nature of biological self-organization per se in humans. Specifically, we consider the role of the immune system in biological self-organization in addition to neural/brain systems that furnish us with a sense of self. We examine the complex case of pregnancy, whereby two immune systems need to negotiate the exchange of resources and information in order to maintain viable self-regulation of nested systems. We conclude with a proposal for the mechanisms-that scaffold the complex relationship between two self-organising systems in pregnancy-through the lens of the Active Inference, with a focus on shared Markov blankets.

Cold Mechanical Isolation of Placental Macrophages as a Method to Limit Procedure-Induced Activation of Macrophages

Isolation of placental macrophages using enzymatic digestion at warm temperatures is widely used for in vitro studies. However, studies in brain and kidney tissue show that this method activates immune cells, immediate early genes, and heat shock proteins. Isolating placental macrophages while preserving their tissue-specific characteristics as much as possible is pivotal to reliably studying their functions. We therefore developed a mechanical dissociation protocol at low temperatures and compared this to enzymatic digestion at high temperatures. Decidual and villous macrophages were isolated from term human placentas. A cell suspension was generated by mechanical dissociation using a gentleMACS. For warm enzymatic digestion, Accutase was added, followed by incubation at 37°C. Macrophages were isolated after Ficoll density gradient centrifugation. Cell types were analyzed with flow cytometry (CD45, CD14, CD80, CD86, CD163, and CD206) and their activation status with real-time PCR (FOS, JUN, HSP27, HSP70, IL1β, TNFα, IL10, and TGFβ) after cell sorting. A higher proportion of leukocytes and macrophages was obtained from the villi with cold mechanical dissociation (p < 0.05). Compared to warm enzymatic digestion, cold mechanical dissociation resulted in a higher expression of CD163 in villous and decidual macrophages (p < 0.05). Warm enzymatic digestion showed higher levels of TNFα, IL1β, and IL10 in decidual and villous macrophages, and HSP70 in villous macrophages. Our data show that mechanical dissociation of placental tissue at low temperatures is associated with less activation of placental macrophages. This suggests that cold mechanical dissociation is a preferred method, resulting in macrophages that more closely resemble their in-tissue state.

Endometrial TGFβ signaling fosters early pregnancy development by remodeling the fetomaternal interface

The endometrium is a unique and highly regenerative tissue with crucial roles during the reproductive lifespan of a woman. As the first site of contact between mother and embryo, the endometrium, and its critical processes of decidualization and immune cell recruitment, play a leading role in the establishment of pregnancy, embryonic development, and reproductive capacity. These integral processes are achieved by the concerted actions of steroid hormones and a myriad of growth factor signaling pathways. This review focuses on the roles of the transforming growth factor β (TGFβ) pathway in the endometrium during the earliest stages of pregnancy through the lens of immune cell regulation and function. We discuss how key ligands in the TGFβ family signal through downstream SMAD transcription factors and ultimately remodel the endometrium into a state suitable for embryo implantation and development. We also focus on the key roles of the TGFβ signaling pathway in recruiting uterine natural killer cells and their collective remodeling of the decidua and spiral arteries. By providing key details about immune cell populations and TGFβ signaling within the endometrium, it is our goal to shed light on the intricate remodeling that is required to achieve a successful pregnancy.

βhCG mediates immune suppression through upregulation of CD11b+ Gr1+ myeloid derived suppressor cells, CD206+ M2 macrophages, and CD4+ FOXP3+ regulatory T-cells in BRCA1 deficient breast cancers

BRCA1 mutation is reported in about 70% of all triple negative breast cancers (TNBC), while BRCA1 defect due to promoter hypermethylation is seen in about 30%-60% of sporadic breast cancers. Although PARP inhibitors and platinum-based chemotherapy are used to treat these cancers, more efficient therapeutic approaches are required to overcome the resistance to treatment. Our previous findings have reported elevated βhCG expression but not αhCG in BRCA1 deficient breast cancers. As βhCG causes immune suppression in pregnancy, this study explored the immunomodulatory effect of βhCG in BRCA1mutated/deficient TNBC. We observed that Th1, Th2, and Th17 cytokines are upregulated in the presence of βhCG in BRCA1 defective cancers. In NOD-SCID and syngeneic mouse models, βhCG increases the frequency of Myeloid-derived suppressor cells in tumour tissues and contributes to macrophage reprogramming from antitumor M1 to pro-tumour M2 phenotype. βhCG reduces the CD4+ T-cell infiltration while increasing the density of CD4+ CD25+ FOXP3+ regulatory T-cell in BRCA1 deficient tumour tissues. In contrast, xenograft tumours with βhCG knocked down TNBC cells did not show these immune suppressive effects. We have also shown that βhCG upregulates pro-tumorigenic markers arginase1(Arg1), inducible nitric oxide synthase, PD-L1/PD-1, and NFκB in BRCA1 defective tumours. Thus, for the first time, this study proves that βhCG suppresses the host antitumor immune response and contributes to tumour progression in BRCA1 deficient tumours. This study will help develop new immunotherapeutic approaches for treating BRCA1 defective TNBC by regulating βhCG.

Functions of LncRNAs, exosomes derived MSCs and immune regulatory molecules in preeclampsia disease

Modulatory signaling pathway such as T cell immunoreceptor with Ig and ITIM domains (TIGIT), Cytotoxic T-Lymphocyte Associated Protein 4 (CTLA-4), P53 signaling and TIM (T-cell immunoglobin and mucin domain) are important in normal pregnancy and loss of their functions or dysregulation of related genes can lead to some disorders. Inflammation is a process by which your body's white blood cells and the things they make protect you from infection from outside invaders, such as bacteria and viruses. Some cellular and molecular signaling have been categorized to demonstrate the mechanism that protects tolerance to antigens. lncRNAs significantly impact physiological processes like immunity and metabolism, and are linked to tumors, cardiovascular diseases, nervous system disorders, and nephropathy.In this review article, we summarized recent studies about the role of TIGIT, CTLA-4, P53 and TIM regulatory molecules and reviewed dysregulation of these pathway in diseases.We will also talk about the role of lncRNAs and mesenchymal stem cells.

Pro- and anti-inflammatory cytokines and growth factors in patients undergoing in vitro fertilization procedure treated with prednisone

Embryo implantation is a key moment in pregnancy. Abnormal production of pro- and anti-inflammatory cytokines, their receptors and other immune factors may result in embryo implantation failure and pregnancy loss. The aim of this study was to determine the profile of selected pro- and anti-inflammatory factors in the blood plasma of patients undergoing in vitro fertilization (IVF) and control women who achieved pregnancy after natural conception. The examined patients were administered steroid prednisone. We present results concern the plasma levels of IFN-ɣ, BDNF, LIF, VEGF-A, sTNFR1 and IL-10. We found that IVF patients receiving steroids differed significantly from patients who were not administered such treatment in terms of IFN-γ and IL-10 levels. Moreover, IVF patients differed in secretion of all tested factors with the fertile controls. Our results indicated that women who secrete at least 1409 pg/ml of sTNFR1 have a chance to become pregnant naturally and give birth to a child, while patients after IVF must achieve a concentration of 962.3 pg/ml sTNFR1 in blood plasma for successful pregnancy. In addition, IVF patients secreting VEGF-A above 43.28 pg/ml have a greater risk of miscarriage or a failed transfer in comparison to women secreting below this value. In conclusion, fertile women present a different profile of pro- and anti-inflammatory cytokines, and growth factors compared to patients with recurrent implantation failure (RIF).

Association of the LEP gene with immune infiltration as a diagnostic biomarker in preeclampsia

Objective: Preeclampsia (PE) is a serious condition in pregnant women and hence an important topic in obstetrics. The current research aimed to recognize the potential and significant immune-related diagnostic biomarkers for PE. Methods: From the Gene Expression Omnibus (GEO) data sets, three public gene expression profiles (GSE24129, GSE54618, and GSE60438) from the placental samples of PE and normotensive pregnancy were downloaded. Differentially expressed genes (DEGs) were selected and determined among 73 PE and 85 normotensive control pregnancy samples. The DEGs were used for Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Disease Ontology (DO) enrichment analysis, and Gene Set Enrichment Analysis (GSEA). The candidate biomarkers were identified by the least absolute shrinkage and selection operator (LASSO) and support vector machine recursive feature elimination (SVM-RFE) analysis. The receiver operating characteristic curve (ROC) was applied to evaluate diagnostic ability. For further confirmation, the expression levels and diagnostic value of biomarkers in PE were verified in the GSE75010 data set (80 PE and 77 controls) and validated by qRT-RCR, Western blot, and immunohistochemistry (IHC). The CIBERSORT algorithm was used to calculate the compositional patterns of 22 types of immune cells in PE. Results: In total, 15 DEGs were recognized. The GO and KEGG analyses revealed that the DEGs were enriched in the steroid metabolic process, receptor ligand activity, GnRH secretion, and neuroactive ligand-receptor interaction. The recognized DEGs were primarily implicated in cell-type benign neoplasm, kidney failure, infertility, and PE. Gene sets related to hormone activity, glycosylation, multicellular organism process, and response to BMP were activated in PE. The LEP gene was distinguished as a diagnostic biomarker of PE (AUC = 0.712) and further certified in the GSE75010 data set (AUC = 0.850). The high expression of LEP was associated with PE in clinical samples. In addition, the analysis of the immune microenvironment showed that gamma delta T cells, memory B cells, M0 macrophages, and regulatory T cells were positively correlated with LEP expression (P < 0.05). Conclusion: LEP expression can be considered to be a diagnostic biomarker of PE and can offer a novel perspective for future studies regarding the occurrence and molecular mechanisms of PE.

Decidual lymphatic endothelial cell-derived granulocyte-macrophage colony-stimulating factor induces M1 macrophage polarization via the NF-κB pathway in severe pre-eclampsia

PROBLEM

Direct interactions between macrophages and lymphatic vessels have been shown previously. In pre-eclampsia (PE), macrophages are dominantly polarized into a proinflammatory M1 phenotype and lymphangiogenesis is defective in the decidua. Here, we investigated whether decidual lymphatic endothelial cells (dLECs) affect macrophage polarization in PE.

METHOD OF STUDY

THP-1 macrophages were cocultured with dLECs or cultured in the conditioned medium (CM) of dLECs. Macrophage polarization was measured using flow cytometry. Granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in dLECs was measured using qRT-PCR and ELISA. The activation of nuclear translocation of nuclear factor-κ (NF-κB), an upstream signaling molecule of GM-CSF, was assessed by immunocytochemical localization of p65. Through GM-CSF knockdown and NF-κB inhibition in dLEC, we evaluated whether the GM-CSF/NF-κB pathway of PE dLEC affects decidual macrophage polarization.

RESULTS

The ratio of inflammatory M1 macrophages with HLA-DR⁺ /CD80⁺ markers significantly increased following coculturing with PE dLECs or culturing in PE dLEC CM, indicating that the PE dLEC-derived soluble factor acts in a paracrine manner. GM-CSF expression was significantly upregulated in PE dLECs. Recombinant human GM-CSF induced macrophage polarization toward an M1-like phenotype, whereas its knockdown in PE dLECs suppressed it, suggesting PE dLECs induce M1 macrophage polarization by secreting GM-CSF. The NF-κB p65 significantly increased in PE dLECs compared to the control, and pretreatment with an NF-κB inhibitor significantly suppressed GM-CSF production from PE dLECs.

CONCLUSIONS

In PE, dLECs expressing high levels of GM-CSF via the NF-κB-dependent pathway play a role in inducing decidual M1 macrophage polarization.

Whole-transcriptome analysis reveals virulence-specific pathogen-host interactions at the placenta in bovine neosporosis

Research on bovine neosporosis has achieved relevant milestones, but the mechanisms underlying the occurrence of foetal death or protection against foetal death remain unclear. In a recent study, placentas from heifers challenged with the high-virulence isolate Nc-Spain7 exhibited focal necrosis and inflammatory infiltrates as soon as 10 days post-infection (dpi), although parasite detection was minimal. These lesions were more frequent at 20 dpi, coinciding with higher rates of parasite detection and the occurrence of foetal death in some animals. In contrast, such lesions were not observed in placentas from animals infected with the low-virulence isolate Nc-Spain1H, where the parasite was detected only in placenta from one animal at 20 dpi. This work aimed to study which mechanisms are triggered in the placentas (caruncles and cotyledons) of these pregnant heifers at early stages of infection (10 and 20 dpi) through whole-transcriptome analysis. In caruncles, infection with the high-virulence isolate provoked a strong proinflammatory response at 10 dpi. This effect was not observed in heifers infected with the low-virulence isolate, where IL-6/JAK/STAT3 signalling and TNF-alpha signalling via NF-κB pathways were down-regulated. Interestingly, the expression of E2F target genes, related to restraining the inflammatory response, was higher in these animals. At 20 dpi, more pronounced proinflammatory gene signatures were detectable in heifers infected with the high-virulence isolate, being more intense in heifers carrying dead fetuses. However, the low-virulence isolate continued without activating the proinflammatory response. In cotyledons, the response to infection with the high-virulence isolate was similar to that observed in caruncles; however, the low-virulence isolate induced mild proinflammatory signals at 20 dpi. Finally, a deconvolutional analysis of gene signatures from both placentome tissues revealed a markedly higher fraction of activated natural killers, M1 macrophages and CD8+ T cells for the high-virulence isolate. Therefore, our transcriptomic analysis supports the hypothesis that an intense immune response probably triggered by parasite multiplication could be a key contributor to abortion. Further studies are required to determine the parasite effectors that govern the distinct interactions of high- and low-virulence isolates with the host, which could help elucidate the molecular processes underlying the pathogenesis of neosporosis in cattle.

The Mac Is Back: The Role of Macrophages in Human Healthy and Complicated Pregnancies

Pregnancy is a fascinating immunological paradox: the semi-allogeneic fetus generally grows without any complications. In the placenta, fetal trophoblast cells come into contact with maternal immune cells. Inaccurate or inadequate adaptations of the maternal immune system could lead to problems with the functioning of the placenta. Macrophages are important for tissue homeostasis, cleanup, and the repair of damaged tissues. This is crucial for a rapidly developing organ such as the placenta. The consensus on macrophages at the maternal-fetal interface in pregnancy is that a major proportion have an anti-inflammatory, M2-like phenotype, that expresses scavenger receptors and is involved in tissue remodeling and the dampening of the immune reactions. Recent multidimensional analyses have contributed to a more detailed outlook on macrophages. The new view is that this lineage represents a highly diverse phenotype and is more prevalent than previously thought. Spatial-temporal in situ analyses during gestation have identified unique interactions of macrophages both with trophoblasts and with T cells at different trimesters of pregnancy. Here, we elaborate on the role of macrophages during early human pregnancy and at later gestation. Their possible effect is reviewed in the context of HLA incompatibility between mother and fetus, first in naturally conceived pregnancies, but foremost in pregnancies after oocyte donation. The potential functional consequences of macrophages for pregnancy-related immune reactions and the outcome in patients with recurrent pregnancy loss are also discussed.

Endometrial immune cell ratios and implantation success in patients with recurrent implantation failure

The objective of this study was to compare the endometrial immune cells quantities and ratios during the mid-luteal phase between women with recurrent implantation failure (RIF) with successful and unsuccessful embryo implantation. For this purpose, endometrial biopsies from 116 women aged between 29 and 46 with history of RIF undergoing Assisted Reproductive Technology (ART) without endometrial pathologies were immunohistochemically stained for CD3 + T-cells, CD4 + T-helpers, CD8 + T-killers, CD14 + monocytes, CD68 + macrophages, CD56 + NK cells and CD79α+ B-cells. Endometrial immune cells quantities and ratios were compared based on the embryo implantation outcome in the subsequent embryo transfer cycle. Spearman correlation analysis and Mann-Whitney U test were used to analyse the obtained data. Patients who experienced successful implantation at the subsequent cycle had significantly lower percentage of CD3 + T cells, and higher ratios of CD4 + /CD8 + , CD4 + /CD3 + and CD68 + /CD3 + than the patients who experienced another failure in implantation. In addition, the ratios of CD3 + /CD14 + , CD79α+ /CD14 + and CD56 + /CD14 + were significantly lower in the successful implantation group than that in the unsuccessful one. A cut off value of CD68 + /CD3 + ratio higher than 0.85 (AUC 0.67, 95% CI 0.56-0.79), CD4 + /CD3 + ratio higher than 0.19 (AUC 0.67, 95% CI 0.56-0.79) and CD4 + /CD8 + ratio higher than 0.43 (AUC 0.62, 95% CI 0.50-0.73) could be predictive factors for successful implantation in RIF patients. Knowledge on the immune cell composition could assist in the evaluation of the endometrial receptivity in RIF patients.

Efficacy of intrauterine infusion therapy before embryo transfer in recurrent implantation failure: A systematic review and network meta-analysis

Previous studies of intrauterine infusion therapy in recurrent implantation failure (RIF) patients have shown conflicting results, and there is a lack of head-to-head horizontal comparisons between different drugs. This study aimed to assess the effectiveness of four intrauterine infusion drugs, including human chorionic gonadotropin (HCG), granulocyte colony-stimulating factor (G-CSF), peripheral blood mononuclear cells (PBMCs) and autologous platelet-rich plasma (PRP), in improving pregnancy outcomes in RIF patients through the network meta-analysis. Randomized controlled trials (RCTs) of preimplantation intrauterine infusion for RIF were searched in the Cochrane Library, Embase, Medline and CINAHL. Meanwhile, relevant data were extracted and Stata 15.0 software was applied to statistical analysis. A total of 21 studies with a sample size of 2917 cases were included in this study. Clinical pregnancy rate network meta-analysis showed that, intrauterine infusion of all four drugs is significantly better than the blank and placebo groups, while only PRP could significantly increase live birth rate compared with the blank and placebo groups. The SUCRA plots of clinical pregnancy and live birth rates showed a higher ranking of PRP and PBMCs. Early abortion intervention analysis found that only G-CSF is significantly better than the blank and placebo groups, and the SUCRA plot of G-CSF showed the highest ranking. All these findings confirmed that all four intrauterine infusion drugs can improve pregnancy outcomes in RIF patients to varying degrees, with PRP being the most effective. Further prospective, large-scale and high-quality RCTs are still necessary to determine the exact subgroups of benefit for the different drugs.

Immunopathological insights into villitis of unknown etiology on the basis of transplant immunology

Villitis of unknown etiology (VUE) is an inflammatory disease characterized by the infiltration of maternal CD8 +T cells into the placental villi. Although the pathogenesis of VUE is still debated, dysregulation of the immune system appears to be an important factor in the development of the disease. Interaction of maternal T cells with the fetal antigens seems to be the trigger for the VUE onset. In this context, graft vs host disease (GVHD) and allographic rejection seem to share similarities in the VUE immunopathological mechanism, especially those related to immunoregulation. In this review, we compared the immunological characteristics of VUE with allograft rejection, and GVHD favoring a better knowledge of VUE pathogenesis that may contribute to VUE therapeutics strategies in the future.

Streptococcus agalactiae npx Is Required for Survival in Human Placental Macrophages and Full Virulence in a Model of Ascending Vaginal Infection during Pregnancy

Streptococcus agalactiae, also known as group B Streptococcus (GBS), is a Gram-positive encapsulated bacterium that colonizes the gastrointestinal tract of 30 to 50% of humans. GBS causes invasive infection during pregnancy that can lead to chorioamnionitis, funisitis, preterm prelabor rupture of membranes (PPROM), preterm birth, neonatal sepsis, and maternal and fetal demise. Upon infecting the host, GBS encounters sentinel innate immune cells, such as macrophages, within reproductive tissues. Once phagocytosed by macrophages, GBS upregulates the expression of the gene npx, which encodes an NADH peroxidase. GBS mutants with an npx deletion (Δnpx) are exquisitely sensitive to reactive oxygen stress. Furthermore, we have shown that npx is required for GBS survival in both THP-1 and placental macrophages. In an in vivo murine model of ascending GBS vaginal infection during pregnancy, npx is required for invading reproductive tissues and is critical for inducing disease progression, including PPROM and preterm birth. Reproductive tissue cytokine production was also significantly diminished in Δnpx mutant-infected animals compared to that in animals infected with wild-type (WT) GBS. Complementation in trans reversed this phenotype, indicating that npx is critical for GBS survival and the initiation of proinflammatory signaling in the gravid host. IMPORTANCE This study sheds new light on the way that group B Streptococcus (GBS) defends itself against oxidative stress in the infected host. The enzyme encoded by the GBS gene npx is an NADH peroxidase that, our study reveals, provides defense against macrophage-derived reactive oxygen stress and facilitates infections of the uterus during pregnancy. This enzyme could represent a tractable target for future treatment strategies against invasive GBS infections.

Untargeted metabolomics analysis reveals Mycobacterium tuberculosis strain H37Rv specifically induces tryptophan metabolism in human macrophages

Background

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M. tb) remains a global health issue. The characterized virulent M. tb H37Rv, avirulent M. tb H37Ra and BCG strains are widely used as reference strains to investigate the mechanism of TB pathogenicity. Here, we attempted to determine metabolomic signatures associated with the Mycobacterial virulence in human macrophages through comparison of metabolite profile in THP-1-derived macrophages following exposure to the M. tb H37Rv, M. tb H37Ra and BCG strains.

Results

Our findings revealed remarkably changed metabolites in infected macrophages compared to uninfected macrophages. H37Rv infection specifically induced 247 differentially changed metabolites compared to H37Ra or BCG infection. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed H37Rv specifically induces tryptophan metabolism. Moreover, quantitative PCR (qPCR) results showed that indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase 2 (TDO2) which converts the tryptophan to a series of biologically second metabolites were up-regulated in H37Rv-infected macrophages compared to H37Ra- or BCG-infected macrophages, confirming the result of enhanced tryptophan metabolism induced by H37Rv infection. These findings indicated that targeting tryptophan (Trp) metabolism may be a potential therapeutic strategy for pulmonary TB.

Conclusions

We identified a number of differentially changed metabolites that specifically induced in H37Rv infected macrophages. These signatures may be associated with the Mycobacterial virulence in human macrophages. The present findings provide a better understanding of the host response associated with the virulence of the Mtb strain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02659-y.

Urticaria in Pregnancy and Lactation

Chronic urticaria (CU) is a mast cell-driven chronic inflammatory disease with a female predominance. Since CU affects mostly females in reproductive age, pregnancy is an important aspect to consider in the context of this disease. Sex hormones affect mast cell (MC) biology, and the hormonal changes that come with pregnancy can modulate the course of chronic inflammatory conditions, and they often do. Also, pregnancy-associated changes in the immune system, including local adaptation of innate and adaptive immune responses and skewing of adaptive immunity toward a Th2/Treg profile have been linked to changes in the course of inflammatory diseases. As of now, little is known about the effects of pregnancy on CU and the outcomes of pregnancy in CU patients. Also, there are no real-life studies to show the safety of urticaria medications during pregnancy. The recent PREG-CU study provided the first insights on this and showed that CU improves during pregnancy in half of the patients, whereas it worsens in one-third; and two of five CU patients experience flare-ups of their CU during pregnancy. The international EAACI/GA2LEN/EuroGuiDerm/APAAACI guideline for urticaria recommends adopting the same management strategy in pregnant and lactating CU patients; starting treatment with standard doses of second-generation (non-sedative) H1 antihistamines, to increase the dose up to 4-folds in case of no response, and to add omalizumab in antihistamine-refractory patients; but also emphasizes the lack of evidence-based information on the safety and efficacy of urticaria treatments during pregnancy. The PREG-CU study assessed treatments and their outcomes during pregnancy. Here, we review the reported effects of sex hormones and pregnancy-specific immunological changes on urticaria, we discuss the impact of pregnancy on urticaria, and we provide information and guidance on the management of urticaria during pregnancy and lactation.

Significance of Placental Mesenchymal Stem Cell in Placenta Development and Implications for Preeclampsia

The well-developed placentation is fundamental for the reproductive pregnancy while the defective placental development is the pathogenetic basis of preeclampsia (PE), a dangerous complication of pregnancy comprising the leading causes of maternal and perinatal morbidity and mortality. Placenta-derived mesenchymal stem cells (PMSCs) are a group of multipotent stem cells that own a potent capacity of differentiating into constitutive cells of vessel walls. Additionally, with the paracrine secretion of various factors, PMSCs inextricably link and interact with other component cells in the placenta, collectively improving the placental vasculature, uterine spiral artery remolding, and uteroplacental interface immunoregulation. Recent studies have further indicated that preeclamptic PMSCs, closely implicated in the abnormal crosstalk between other ambient cells, disturb the homeostasis and development in the placenta. Nevertheless, PMSCs transplantation or PMSCs exosome therapies tend to improve the placental vascular network and trophoblastic functions in the PE model, suggesting PMSCs may be a novel and putative therapeutic strategy for PE. Herein, we provide an overview of the multifaceted contributions of PMSCs in early placental development. Thereinto, the intensive interactions between PMSCs and other component cells in the placenta were particularly highlighted and further extended to the implications in the pathogenesis and therapeutic strategies of PE.

Immune determinants of endometrial receptivity: a biological perspective

Immune cells are essential for endometrial receptivity to embryo implantation and early placental development. They exert tissue-remodeling and immune regulatory roles-acting to promote epithelial attachment competence, regulate the differentiation of decidual cells, remodel the uterine vasculature, control and resolve inflammatory activation, and suppress destructive immunity to paternally inherited alloantigens. From a biological perspective, the endometrial immune response exerts a form of "quality control"-it promotes implantation success when conditions are favorable but constrains receptivity when physiological circumstances are not ideal. Women with recurrent implantation failure and recurrent miscarriage may exhibit altered numbers or disturbed function of certain uterine immune cell populations-most notably uterine natural killer cells and regulatory T cells. Preclinical and animal studies indicate that deficiencies or aberrant activation states in these cells can be causal in the pathophysiological mechanisms of infertility. Immune cells are, therefore, targets for diagnostic evaluation and therapeutic intervention. However, current diagnostic tests are overly simplistic and have limited clinical utility. To be more informative, they need to account for the full complexity and reflect the range of perturbations that can occur in uterine immune cell phenotypes and networks. Moreover, safe and effective interventions to modulate these cells are in their infancy, and personalized approaches matched to specific diagnostic criteria will be needed. Here we summarize current biological understanding and identify knowledge gaps to be resolved before the promise of therapies to target the uterine immune response can be fully realized.

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

Maternal tolerance to semi- or fully allograft conceptus is a prerequisite for the maintenance of pregnancy. Once this homeostasis is disrupted, it may result in pregnancy loss. As a potential approach to prevent pregnancy loss, targeting decidual immune cells (DICs) at the maternal-fetal interface has been suggested. Although the phenotypic features and functions of DIC have been extensively profiled, the regulatory pathways for this unique immunological adaption have yet to be elucidated. In recent years, a pivotal mechanism has been highlighted in the area of immunometabolism, by which the changes in intracellular metabolic pathways in DIC and interaction with the adjacent metabolites in the microenvironment can alter their phenotypes and function. More inspiringly, the manipulation of metabolic profiling in DIC provides a novel avenue for the prevention and treatment of pregnancy loss. Herein, this review highlights the major metabolic programs (specifically, glycolysis, ATP-adenosine metabolism, lysophosphatidic acid metabolism, and amino acid metabolism) in multiple immune cells (including decidual NK cells, macrophages, and T cells) and their integrations with the metabolic microenvironment in normal pregnancy. Importantly, this perspective may help to provide a potential therapeutic strategy for reducing pregnancy loss via targeting this interplay.

Placental Inflammasome mRNA Levels Differ by Mode of Delivery and Fetal Sex

Parturition signals the end of immune tolerance in pregnancy. Term labour is usually a sterile inflammatory process triggered by damage associated molecular patterns (DAMPs) as a consequence of functional progesterone withdrawal. Activation of DAMPs recruits leukocytes and inflammatory cytokine responses in the myometrium, decidua, cervix and fetal membranes. Emerging evidence shows components of the inflammasome are detectable in both maternal decidua and placenta. However, the activation of the placental inflammasome with respect to mode of delivery has not been profiled. Placental chorionic villus samples from women delivering at term via unassisted vaginal (UV) birth, labouring lower segment caesarean section (LLSCS, emergency caesarean section) and prelabour lower segment caesarean section (PLSCS, elective caesarean section) underwent high throughput RNA sequencing (NextSeq Illumina) and bioinformatic analyses to identify differentially expressed inflammatory (DE) genes. DE genes (IL1RL1, STAT1, STAT2, IL2RB, IL17RE, IL18BP, TNFAIP2, TNFSF10 and TNFRSF8), as well as common inflammasome genes (IL1B, IL1R1, IL1R2, IL6, IL18, IL18R1, IL18R1, IL10, and IL33), were targets for further qPCR analyses and Western blotting to quantify protein expression. There was no specific sensor molecule-activated inflammasome which dominated expression when stratified by mode of delivery, implying that multiple inflammasomes may function synergistically during parturition. Whilst placentae from women who had UV births overall expressed pro-inflammatory mediators, placentae from LLSCS births demonstrated a much greater pro-inflammatory response, with additional interplay of pro- and anti-inflammatory mediators. As expected, inflammasome activation was very low in placentae from women who had PLSCS births. Sex-specific differences were also detected. Placentae from male-bearing pregnancies displayed higher inflammasome activation in LLSCS compared with PLSCS, and placentae from female-bearing pregnancies displayed higher inflammasome activation in LLSCS compared with UV. In conclusion, placental inflammasome activation differs with respect to mode of delivery and neonatal sex. Its assessment may identify babies who have been exposed to aberrant inflammation at birth that may compromise their development and long-term health and wellbeing.

Cellular and molecular atlas of the placenta from a COVID-19 pregnant woman infected at midgestation highlights the defective impacts on foetal health

OBJECTIVES

The impacts of the current COVID-19 pandemic on maternal and foetal health are enormous and of serious concern. However, the influence of SARS-CoV-2 infection at early-to-mid gestation on maternal and foetal health remains unclear.

MATERIALS AND METHODS

Here, we report the follow-up study of a pregnant woman of her whole infective course of SARS-CoV-2, from asymptomatic infection at gestational week 20 to mild and then severe illness state, and finally cured at Week 24. Following caesarean section due to incomplete uterine rupture at Week 28, histological examinations on the placenta and foetal tissues as well as single-cell RNA sequencing (scRNA-seq) for the placenta were performed.

RESULTS

Compared with the gestational age-matched control placentas, the placenta from this COVID-19 case exhibited more syncytial knots and lowered expression of syncytiotrophoblast-related genes. The scRNA-seq analysis demonstrated impaired trophoblast differentiation, activation of antiviral and inflammatory CD8 T cells, as well as the tight association of increased inflammatory responses in the placenta with complement over-activation in macrophages. In addition, levels of several inflammatory factors increased in the placenta and foetal blood.

CONCLUSION

These findings illustrate a systematic cellular and molecular signature of placental insufficiency and immune activation at the maternal-foetal interface that may be attributed to SARS-CoV-2 infection at the midgestation stage, which highly suggests the extensive care for maternal and foetal outcomes in pregnant women suffering from COVID-19.

Obesity and Maternal-Placental-Fetal Immunology and Health

Obesity rates in women of childbearing age is now at 29%, according to recent CDC reports. It is known that obesity is associated with oxidative stress and inflammation, including disruptions in cellular function and cytokine levels. In pregnant women who are obese, associated placental dysfunction can lead to small for gestational age (SGA) infants. More frequently, however, maternal obesity is associated with large for gestational age (LGA) newborns, who also have higher incidence of metabolic disease and asthma due to elevated levels of inflammation. In addition, anthropogenic environmental exposures to "endocrine disrupting" and "forever" chemicals affect obesity, as well as maternal physiology, the placenta, and fetal development. Placental function is intimately associated with the control of inflammation during pregnancy. There is a large amount of literature examining the relationship of placental immunology, both cellular and humoral, with pregnancy and neonatal outcomes. Cells such as placental macrophages and NK cells have been implicated in spontaneous miscarriage, preeclampsia, preterm birth, perinatal neuroinflammation, and other post-natal conditions. Differing levels of placental cytokines and molecular inflammatory mediators also have known associations with preeclampsia and developmental outcomes. In this review, we will specifically examine the literature regarding maternal, placental, and fetal immunology and how it is altered by maternal obesity and environmental chemicals. We will additionally describe the relationship between placental immune function and clinical outcomes, including neonatal conditions, autoimmune disease, allergies, immunodeficiency, metabolic and endocrine conditions, neurodevelopment, and psychiatric disorders.

Effectiveness comparison between Endometrial Receptivity Array, Immune Profiling and the combination in treating patients with multiple implantation failure

PROBLEM

The clinical value of endometrial receptivity array (ERA), endometrial immune profiling, or a combination of both for multiple implantation failure patients is unclear.

METHOD OF STUDY

One hundred and seventy-two women with a history of at least two or more consecutive implantation failures in IVF/ICSI treatment were included. According to patients' willingness, they were divided into four groups, 'no treatment', 'Immune Profiling', 'ERA' and 'ERA + Immune Profiling'. Endometrial biopsy was examined by ERA, immune profiling alone, or combination, and intention was adopted accordingly. Pregnancy outcomes were compared, and the association between ERA phases and endometrial immune profiling was also assessed.

RESULTS

The overall incidence rate of the displaced window of implantation (WOI) and endometrial immune dysregulations were 84.9% and 75.3%, respectively. Implantation rate was significantly higher in the 'ERA + Immune Profiling' group than the 'no treatment' group (P = 0.007). Clinical pregnancy rate was somewhat improved in the three treatment groups but with a borderline significance (P = 0.071). After controlling for other confounders, 'ERA + Immune Profiling' treatment was associated with a higher pregnancy rate [aOR (95%CI)  =  3.412 (1.387-8.395), P = 0.008]. There was no association between endometrial immune profiling and ERA phases.

CONCLUSIONS

Our findings highlight the high incidence of displaced WOI and endometrial immune dysregulation in multiple implantation failure patients. The combination of ERA and endometrial immune profiling is more likely to have clinical value than ERA or immune profiling alone. These data suggested the unsubstitutability of ERA and endometrial immune profiling on the treatment outcome for multiple implantation failure patients. This article is protected by copyright. All rights reserved.

Role of Transforming Growth Factor-β1 in Regulating Fetal-Maternal Immune Tolerance in Normal and Pathological Pregnancy

Transforming growth factor-β (TGF-β) is composed of three isoforms, TGF-β1, TGF-β2, and TGF-β3. TGF-β1 is a cytokine with multiple biological functions that has been studied extensively. It plays an important role in regulating the differentiation of immune cells and maintaining immune cell functions and immune homeostasis. Pregnancy is a carefully regulated process. Controlled invasion of trophoblasts, precise coordination of immune cells and cytokines, and crosstalk between trophoblasts and immune cells play vital roles in the establishment and maintenance of normal pregnancy. In this systematic review, we summarize the role of TGF-β1 in regulating fetal-maternal immune tolerance in healthy and pathological pregnancies. During healthy pregnancy, TGF-β1 induces the production of regulatory T cells (Tregs), maintains the immunosuppressive function of Tregs, mediates the balance of M1/M2 macrophages, and regulates the function of NK cells, thus participating in maintaining fetal-maternal immune tolerance. In addition, some studies have shown that TGF-β1 is dysregulated in patients with recurrent spontaneous abortion or preeclampsia. TGF-β1 may play a role in the occurrence and development of these diseases and may be a potential target for the treatment of these diseases.

Biomolecular Markers of Recurrent Implantation Failure-A Review

Currently, infertility affects 8–12% of reproductive age couples worldwide, a problem that also affects women suffering from recurrent implantation failure (RIF). RIF is a complex condition resulting from many physiological and molecular mechanisms involving dynamic endometrium–blastocyst interaction. The most important are the endometrial receptivity process, decidualization, trophoblast invasion, and blastocyst nesting. Although the exact multifactorial pathogenesis of RIF remains unclear, many studies have suggested the association between hormone level imbalance, disturbances of angiogenic and immunomodulatory factors, certain genetic polymorphisms, and occurrence of RIF. These studies were performed in quite small groups. Additionally, the results are inconsistent between ethnicities. The present review briefly summarizes the importance of factors involved in RIF development that could also serve as diagnostic determinants. Moreover, our review could constitute part of a new platform for discovery of novel diagnostic and therapeutic solutions for RIF.

CD19 and intraglandular CD163-positivity as prognostic indicators of pregnancy outcome in CD138-negative women with a previous fresh-embryo-transfer failure

Many factors impede embryonic implantation, and excluding obvious known factors such as chronic endometritis, the immune status of the endometrium may be related to pregnancy. Although an abundantly large number of immune cells infiltrate the endometrium during the secretory phase, whether these immune cells can be used as a predictor of prognosis in ART has not yet been clarified. In the present study we therefore retrospectively analyzed 97 CD138-negative women with a previous fresh-embryo-transfer failure. We assessed the expression of CD56+ uNK cells, CD16+ NK cells, CD57+ NK cells, CD68+ pan-macrophages, CD163+ M2 macrophages, CD4+T cells, CD8+T cells, FOXP3+ regulatory T cells, and CD19+ B cells in the endometrium by IHC to evaluate mid-luteal endometrial immune cells as prognostic indicators of pregnancy outcome in the next frozen-embryo-transfer cycle. CD19-positive cells and the intraglandular CD163-positivity rate increased significantly in the clinically non-pregnant group (0.47 % vs. 0.20 %, P =  0.021; 61 % vs. 30 %, P =  0.017). The ratios of CD4/CD8 were also higher in the non-pregnant group (1.96 vs. 1.45, P =  0.005).The area under the ROC curve of CD19 cell number alone, the intraglandular CD163-positivity alone, and CD19 number combined with the intraglandular CD163-positivity were 0.692 (95 % CI, 0.55-0.834), 0.661 (95 % CI, 0.514-0.809), and 0.748 (95 % CI, 0.614-0.882), respectively. The optimal cut-off value of CD19 was 0.464 %, and the clinical pregnancy rate and live-birth rate diminished significantly when the CD19 level was above this cut-off value. Our study suggests that CD19-positive cells and intraglandular CD163-positivity can be used as prognostic indicators of pregnancy outcome in CD138-negative patients who experienced first-fresh-embryo transfer failure.

Robust innate immune responses at the placenta during early gestation may limit in utero HIV transmission

In 2019, >90% of new HIV infections in infants globally occurred vertically. Studies suggest intrauterine transmission most often occurs in the third trimester; however, there are no mechanistic studies to support these observations. We therefore obtained early/mid-gestation and term placentae from 20 HIV/Hepatitis B/CMV negative women. Isolated primary placental macrophages (Hofbauer cells [HCs]) were exposed to HIV-1_BaL and/or interferon (IFN)-α, IFN-β, IFN-λ1, and RIG-I-like receptor (RLR) agonists. qRT-PCR, FACS, ELISA, Luminex, and Western blot analyses determined expression of activation markers, co-receptors, viral antigen, cytokines, antiviral genes, and host proteins. Early gestation HCs express higher levels of CCR5 and exhibit a more activated phenotype. Despite downregulation of CCR5, term HCs were more susceptible to HIV replication. Early gestation HCs displayed a more activated phenotype than term HCs and HIV exposure lead to the further up-regulation of T-cell co-stimulatory and MHC molecules. Limited HIV replication in early/mid gestation HCs was associated with increased secretion of anti-inflammatory cytokines, chemokines, and a more robust antiviral immune response. In contrast, term HCs were more susceptible to HIV replication, associated with dampening of IFN-induced STAT1 and STAT2 protein activation. Treatment of early/mid gestation and term HCs, with type I IFNs or RLR agonists reduced HIV replication, underscoring the importance of IFN and RLR signaling in inducing an antiviral state. Viral recognition and antiviral immunity in early gestation HCs may prevent in utero HIV infection, whereas diminished antiviral responses at term can facilitate transmission. Defining mechanisms and specific timing of vertical transmission are critical for the development of specific vaccines and antiviral therapeutics to prevent new HIV infections in children globally.

Mother-to-child transmission is the main source of HIV infection in children globally. Studies suggest vertical transmission most often occurs late in the third trimester; however, there are no studies to support these observations. Our study shows that gestational age plays a significant role in the ability of placental macrophages to generate robust antiviral responses, which are necessary to prevent or reduce viral burden. Specifically, we show that viral recognition by RIG-I-like receptors and robust antiviral immune responses in placental cells during early gestation may prevent in utero HIV infection. We also demonstrate that term placental macrophages are limited in their antiviral capacity due to restricted type I IFN signaling. Understanding the mechanisms and timing of vertical transmission are important to understand for the development of specific vaccines and antiviral therapeutics to prevent new HIV infections in children globally.

Evolutionary Views of Tuberculosis: Indoleamine 2,3-Dioxygenase Catalyzed Nicotinamide Synthesis Reflects Shifts in Macrophage Metabolism: Indoleamine 2,3-Dioxygenase Reflects Altered Macrophage Metabolism During Tuberculosis Pathogenesis

Indoleamine 2,3-dioxygenase (IDO) is the rate-limiting enzyme in conversion of tryptophan to kynurenines, feeding de novo nicotinamide synthesis. IDO orchestrates materno-foetal tolerance, increasing human reproductive fitness. IDO mediates immune suppression through depletion of tryptophan required by T lymphocytes and other mechanisms. IDO is expressed by alternatively activated macrophages, suspected to play a key role in tuberculosis (TB) pathogenesis. Unlike its human host, Mycobacterium tuberculosis can synthesize tryptophan, suggesting possible benefit to the host from infection with the microbe. Intriguingly, nicotinamide analogues are used to treat TB. In reviewing this field, it is postulated that flux through the nicotinamide synthesis pathway reflects switching between aerobic glycolysis and oxidative phosphorylation in M. tuberculosis-infected macrophages. The evolutionary cause of such shifts may be ancient mitochondrial behavior related to reproductive fitness. Evolutionary perspectives on the IDO pathway may elucidate why, after centuries of co-existence with the Tubercle bacillus, humans still remain susceptible to TB disease.

Chemerin promotes the pathogenesis of preeclampsia by activating CMKLR1/p-Akt/CEBPɑ axis and inducing M1 macrophage polarization

A higher ratio of M1/M2 macrophages and an elevated chemerin level are both related to increased risk of preeclampsia. However, the crosstalk between these two events and their collective contribution to preeclampsia are not well understood. In this study, we assessed the impacts of chemerin chemokine-like receptor 1 (CMKLR1)/p-Akt/CEBPα axis in regulating macrophage polarization and mediating the pathogenic effects of chemerin on preeclampsia. We showed that chemerin, in a dose- and time-dependent manner, stimulated M1 macrophage polarization, inhibited macrophage-induced trophoblast invasion and migration, and suppressed macrophage-mediated angiogenesis. All these chemerin-induced phenotypes are essentially mediated by sequentially CMKLR1, Akt activation, and CEBPα. Mechanistically, CEBPα acted as a transcriptional activator for both IRF8 and chemerin. In vivo, chemerin aggravated preeclampsia, while α-NETA, an inhibitor for CMKLR1, significantly suppressed M1 macrophage polarization and alleviated preeclampsia. In summary, chemerin, by activating CMKLR1/Akt/CEBPα axis, forms a positive feedback loop, promotes M1 macrophage polarization, suppresses trophoblast migration/invasion and angiogenesis, and contributes to preeclampsia. Therefore, targeting chemerin signaling may benefit the prevention and/or treatment of preeclampsia.

The Role of Immune Cells in Recurrent Spontaneous Abortion

Recurrent spontaneous abortion affects approximately 1–2% of women of childbearing, and describes a condition in which women suffer from three or more continuous spontaneous miscarriages. However, the origin of recurrent spontaneous abortion (RSA) remains unknown, preventing effective treatment and placing stress upon patients. It has been acknowledged that successful pregnancy necessitates balanced immune responses. Therefore, immunological aberrancy may be considered a root cause of poor pregnancy outcomes. Considerable published studies have investigated the relationship between various immune cells and RSA. Here, we review current knowledge on this area, and discuss the five main categories of immune cells involved in RSA; these include innate lymphocytes (ILC), macrophages, decidual dendritic cells (DCs), and T cells. Furthermore, we sought to summarize the impact of the multiple interactions of various immune cells on the emergence of RSA. A good understanding of pregnancy-induced immunological alterations could reveal new therapeutic strategies for favorable pregnancy outcomes.

Dysfunction of Decidual Macrophages Is a Potential Risk Factor in the Occurrence of Preeclampsia

Preeclampsia is a multi-factorial and multi-genetic disorder that affects more than eight million mother and baby pairs each year. Currently, most of the attention to the pathogenesis of preeclampsia has been focused on placenta, but recent progresses suggest that excellent decidualization lays foundation for placentation and growth. Moreover, preeclampsia is associated with an imbalance in immunoregulatory mechanisms, however, how the immune regulatory system in the decidua affects preeclampsia is still unclear. In our study, after intersecting the genes of differentially expressed between preeclampsia and the control gotten by conventional expression profile analysis and the genes contained in the ligand receptor network, we found eight differentially expressed genes in a ligand-receptor relationship, and the eight genes have a characteristic: most of them participate in the interaction between decidual macrophages and other decidual immune cells. The results of single-cell sequencing of decidual cells further demonstrated that decidual macrophages affect the functions of other immune cells through export. As a result, abnormal gene expression affects the export function of decidual macrophages, which in turn affects the interaction of decidual macrophages with other immune cells, thereby destroying the original immune regulation mechanism, and ultimately leading to the occurrence of preeclampsia.

Decidual factors and vasoactive intestinal peptide guide monocytes to higher migration, efferocytosis and wound healing in term human pregnancy

AIM

To explore the functional profile of circulating monocytes and decidual macrophages at term human pregnancy and their contribution to tissue repair upon stimulation ex vivo with decidual factors and the vasoactive intestinal peptide (VIP).

METHODS

Peripheral blood monocytes were isolated from pregnant and non-pregnant volunteers and tested in vitro with decidual explants from term placenta and VIP. The effect of VIP on decidual explants and the effect of its conditioned media on monocytes or decidual macrophages isolated by magnetic beads was carried out by RT-qPCR and ELISA for cytokines expression and release. Migration assays were performed in transwell systems. Efferocytosis was assessed in monocytes or decidual macrophages with CFSE-labelled autologous apoptotic neutrophils and quantified by flow cytometry. Monocyte and decidual macrophages wound healing capacity was evaluated using human endometrial stromal cell monolayers. Immunohistochemistry was performed in serial tissue sections of different placentas.

RESULTS

VIP is expressed in the villi as well as in trophoblast giant cells distributed within the decidua of term placenta. VIP induced the expression of antiinflmammatory markers and monocyte chemoattractant CCL2 and CCL3 in decidual tissues. Monocytes presented higher migration towards decidual explants than CD4 and CD8 cells. VIP-conditioned monocytes displayed an enhanced efferocytosis and wound healing capacity comparable to that of decidual macrophages. Moreover limited efferocytosis of pregnant women monocytes was restored by VIP-induced decidual factors.

CONCLUSION

Results show the conditioning of monocytes by decidual factors and VIP to sustain processes required for tissue repair and homeostasis maintenance in term placenta.

Stimulation of α7 Nicotinic Acetylcholine Receptor by Nicotine Suppresses Decidual M1 Macrophage Polarization Against Inflammation in Lipopolysaccharide-Induced Preeclampsia-Like Mouse Model

Changes in decidual macrophage polarization affect local inflammatory microenvironment and lead to adverse pregnancy outcomes. However, the regulatory mechanism of macrophage polarization in preeclampsia (PE) remains unclear. In this study, we found that α7nAChR expression was significantly down-regulated in decidual macrophages in PE patients compared to normal pregnant women, accompanied by a reduced proportion of M2 phenotype and an increased proportion of M1 phenotype; these results suggested that the reduced α7nAChR activity might contribute to changes in the polarization of decidual macrophages. Then, we further investigated the regulatory role of α7nAChR activation by nicotine on decidual macrophage polarization and placental remodeling in the PE-like mouse model. The PE mice were obtained by i.p. injection of 10 µg/kg lipopolysaccharide (LPS) gestational day (GD) 13, and 40 µg/kg LPS daily until GD16. Subcutaneous injection of 1.0 mg/kg nicotine was administrated from GD14 to GD18. Nicotine treatment increased the decreased M2 phenotype and inhibited the increased M1 phenotype in decidua of pregnant mice induced by LPS. The levels of pro-inflammatory cytokines in decidua were higher but the levels of anti-inflammatory cytokines were lower in PE mice compared to the controls, nicotine reversed these changes. The level of choline acetyltransferase (CHAT) was reduced in the LPS-treated group, it was increased following nicotine treatment. Damage of spiral artery remodeling and down-regulation of markers related to trophoblast invasion in placentas were found in PE mice; nicotine improved these pathological structures of placentas. α-bungarotoxin (α-BGT) which is specific antagonist for α7nAChR could abolish the effects of nicotine on decidual macrophage polarization, trophoblast arrangement and vascular structure in placental tissue in PE mice. These results suggest that α7nAChR plays an important regulatory role in maternal-fetal inflammation and placental remodeling in preeclampsia and may provide a theoretical basis for the discovery of new strategies for preeclampsia.

The Role of B Cells in PE Pathophysiology: A Potential Target for Perinatal Cell-Based Therapy?

The pathophysiology of preeclampsia (PE) is poorly understood; however, there is a large body of evidence that suggests a role of immune cells in the development of PE. Amongst these, B cells are a dominant element in the pathogenesis of PE, and they have been shown to play an important role in various immune-mediated diseases, both as pro-inflammatory and regulatory cells. Perinatal cells are defined as cells from birth-associated tissues isolated from term placentas and fetal annexes and more specifically from the amniotic membrane, chorionic membrane, chorionic villi, umbilical cord (including Wharton's jelly), the basal plate, and the amniotic fluid. They have drawn particular attention in recent years due to their ability to modulate several aspects of immunity, making them promising candidates for the prevention and treatment of various immune-mediated diseases. In this review we describe main findings regarding the multifaceted in vitro and in vivo immunomodulatory properties of perinatal cells, with a focus on B lymphocytes. Indeed, we discuss evidence on the ability of perinatal cells to inhibit B cell proliferation, impair B cell differentiation, and promote regulatory B cell formation. Therefore, the findings discussed herein unveil the possibility to modulate B cell activation and function by exploiting perinatal immunomodulatory properties, thus possibly representing a novel therapeutic strategy in PE.

Contribution of macrophages to fetomaternal immunological tolerance

The semi-allogeneic fetus develops in a uniquely immune tolerant environment within the uterus. For successful pregnancy, both the innate and adaptive immune systems must favor acceptance of the fetal allograft. Macrophages are the second most abundant immune cells after natural killer (NK) cells in the decidua. In coordination with decidual NK cells and dendritic cells, macrophages aid in implantation, vascular remodeling, placental development, immune tolerance to placental cells, and maintenance of tissue homeostasis at the maternal-fetal interface. Decidual macrophages show the classical activated (M1) and alternatively activated (M2) phenotypes under the influence of the local milieu of growth factors and cytokines, and appropriate temporal regulation of the M1/M2 switch is vital for successful pregnancy. Disturbances in the mechanisms that control the M1/M2 balance and associated functions during pregnancy can trigger a spectrum of pregnancy complications ranging from preeclampsia and fetal growth restriction to preterm delivery. This review addresses various mechanisms of tolerance, focusing on the basic biology of macrophages, their plasticity and polarization, and their protective roles at the immune-privileged maternal-fetal interface, including direct and indirect roles in promoting fetomaternal immune tolerance.

Normalization of endometrial histopathology and endometrial NK cells concentration predict successful pregnancy in repeated implantation failure

OBJECTIVE

The primary objective was to establish the endometrial predictors of clinical pregnancy in a population of repeated implantation failure with oocyte donation after specific endometrial treatment. The secondary one was to evaluate reproduction outcomes in terms of Implantation rate (IR), Clinical pregnancy (CP), Live birth delivery rate (LBDR) and Prematurity, in relation to normalization or no-normalization of the predictors.

METHODS

66 patients were assigned to the study. We ran a Pipelle endometrial biopsy to investigate the endometrium lymphocyte population by Flow Cytometry and abnormal/normal patterns by histopathology in pre/post-treatment. We employed the binary logistic regression model to identify the predictors for CP. For the secondary objective, we assessed the clinical outcomes in function to the normalization or no normalization in post-treatment.

RESULTS

Endometrial histopathology and endometrial NK cell counts resulted in CP predictors (Wald chi2 test (p=0.044 and 0.001)), respectively. We had a higher IR, CP and LBDR when both predictors were normalized in comparison with no normalization (p<0.001). There was a high percentage of prematurity in both normalized vs. non-normalized groups (34.4% (11/32) and 71.43% (5/7), respectively) without significant differences.

CONCLUSION

Endometrial histopathology and endometrial NK cell counts showed that they are valid predictors of pregnancy outcome in repeated implantation failure after treatment. In post-treatment, the pregnancy outcomes were significantly higher in the presence of both normalized predictors. Pregnancy rates were zero in the no-normalization of both predictors. There was a high percentage of prematurity in both groups.

Sexual Dimorphism in Innate Immunity: The Role of Sex Hormones and Epigenetics

Sexual dimorphism refers to differences between biological sexes that extend beyond sexual characteristics. In humans, sexual dimorphism in the immune response has been well demonstrated, with females exhibiting lower infection rates than males for a variety of bacterial, viral, and parasitic pathogens. There is also a substantially increased incidence of autoimmune disease in females compared to males. Together, these trends indicate that females have a heightened immune reactogenicity to both self and non-self-molecular patterns. However, the molecular mechanisms driving the sexually dimorphic immune response are not fully understood. The female sex hormones estrogen and progesterone, as well as the male androgens, such as testosterone, elicit direct effects on the function and inflammatory capacity of immune cells. Several studies have identified a sex-specific transcriptome and methylome, independent of the well-described phenomenon of X-chromosome inactivation, suggesting that sexual dimorphism also occurs at the epigenetic level. Moreover, distinct alterations to the transcriptome and epigenetic landscape occur in synchrony with periods of hormonal change, such as puberty, pregnancy, menopause, and exogenous hormone therapy. These changes are also mirrored by changes in immune cell function. This review will outline the evidence for sex hormones and pregnancy-associated hormones as drivers of epigenetic change, and how this may contribute to the sexual dimorphism. Determining the effects of sex hormones on innate immune function is important for understanding sexually dimorphic autoimmune diseases, sex-specific responses to pathogens and vaccines, and how innate immunity is altered during periods of hormonal change (endogenous or exogenous).

PlGF Immunological Impact during Pregnancy

During pregnancy, the mother’s immune system has to tolerate the persistence of paternal alloantigens without affecting the anti-infectious immune response. Consequently, several mechanisms aimed at preventing allograft rejection, occur during a pregnancy. In fact, the early stages of pregnancy are characterized by the correct balance between inflammation and immune tolerance, in which proinflammatory cytokines contribute to both the remodeling of tissues and to neo-angiogenesis, thus, favoring the correct embryo implantation. In addition to the creation of a microenvironment able to support both immunological privilege and angiogenesis, the trophoblast invades normal tissues by sharing the same behavior of invasive tumors. Next, the activation of an immunosuppressive phase, characterized by an increase in the number of regulatory T (Treg) cells prevents excessive inflammation and avoids fetal immuno-mediated rejection. When these changes do not occur or occur incompletely, early pregnancy failure follows. All these events are characterized by an increase in different growth factors and cytokines, among which one of the most important is the angiogenic growth factor, namely placental growth factor (PlGF). PlGF is initially isolated from the human placenta. It is upregulated during both pregnancy and inflammation. In this review, we summarize current knowledge on the immunomodulatory effects of PlGF during pregnancy, warranting that both innate and adaptive immune cells properly support the early events of implantation and placental development. Furthermore, we highlight how an alteration of the immune response, associated with PlGF imbalance, can induce a hypertensive state and lead to the pre-eclampsia (PE).