What are the roles of macrophages and monocytes in human pregnancy?

Evaluation of Complete Blood Parameters and Inflammation Markers in Spontaneous Preterm Labor

AIM

This study aims to evaluate the relationship between systemic inflammatory markers, derived from complete blood count (CBC) parameters, and spontaneous preterm labor. By comparing these markers between preterm and term pregnancies, the study seeks to determine their potential predictive value for adverse neonatal outcomes, including birth weight, APGAR (appearance, pulse, grimace, activity, and respiration) scores, and neonatal intensive care unit (NICU) admission.

METHODS

This study evaluated inflammatory markers in 478 women with spontaneous preterm labor and a gestational age-matched control group. Blood samples were collected prior to the onset of labor to assess CBC parameters (white blood cells [WBC], red blood cells [RBC], neutrophils, lymphocytes, and platelet counts), as well as various inflammatory ratios, such as the systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and aggregate index of systemic inflammation (AISI). Neonatal outcomes, such as birth weight, APGAR scores, and NICU admission, were recorded.

RESULTS

The preterm group showed significantly higher WBC, RBC, neutrophil, lymphocyte, and platelet counts compared to the control group. MLR, MPR, and MPVLR were notably lower in the preterm group. However, these hematological parameters and inflammatory markers demonstrated limited predictive value for adverse neonatal outcomes, with area under the curve (AUC) values hovering around 0.5.

CONCLUSIONS

WBC, RBC, neutrophils, lymphocytes, and platelet counts, along with inflammatory markers such as MLR, MPR, and MPVLR differ between preterm and term groups and can be derived from a simple CBC test. However, their predictive value for adverse neonatal outcomes remains limited.

A dynamic peripheral immune landscape during human pregnancy

Extensive immune adaptations occur during pregnancy to ensure successful delivery. However, these changes can increase the risk of disease in the mother. Here, we conducted single-cell RNA sequencing on peripheral blood mononuclear cells from pregnant women at different stages of pregnancy to elucidate the dynamic transcriptional changes in the maternal immune system. Gradual reduced cytotoxicity phenotype in highly variable cytotoxic T and natural killer cell types were observed during pregnancy. Reduced T- and B-cell response-related MHC-II and CD40 signaling as well as enhanced protolerance inducible costimulator and activin signaling may underlie the pregnancy-related weakening of adaptive immunity. Conversely, pro-inflammatory genes and pathways were upregulated in monocytes, possibly to compensate for the reduced T-cell response. Moreover, the transition from adaptive immune reduction to activation in late pregnancy in dendritic cells and CD4+ T cells was also detected. Notably, we proposed a novel view of the pro-aging effect of pregnancy from the perspective of immunity, and this effect may be restored postpartum. This work expands our knowledge of pregnancy immunity and may provide insights into the altered disease risks during pregnancy.

Comprehensive Analysis of scRNA-Seq and Bulk RNA-Seq Reveals Transcriptional Signatures of Macrophages in Intrahepatic Cholestasis of Pregnancy

Purpose

Intrahepatic cholestasis of pregnancy (ICP) is a disorder that characterized by maternal pruritus, abnormal liver function, and an elevation in total bile acid concentrations during pregnancy. Immune factors have been recognized as playing a vital role in the mechanism of ICP. However, the underlying mechanisms regulating dysfunctional immune cells and immune genes remain to be fully elucidated.

Patients and Methods

Single-cell RNA sequencing and bulk RNA sequencing data of the placenta were downloaded from the SRA database. The AUCell package, Monocle package and SCENIC package were utilized to explored immune cell activity, cell trajectory and transcription factor, respectively. GO, KEGG, and GSEA were employed to explore potential biological mechanisms. Cell-cell communications were further investigated using the CellChat package. RT-PCR, and Western blot were used to verify the gene expression in placenta.

Results

In placenta cells, macrophages were found to be significantly increased in ICP. Additionally, macrophages exhibited the highest immune gene score and were divided into four subclusters (MF1-4). Our analysis revealed significant elevations in MF2, associated with LPS response and antigen presentation, and MF4, associated with TNF and cytokine production. MF3 displayed an anti-inflammatory phenotype. MF1, closely related to ribosomes and proteins, exhibited a sharp decrease. Although ICP maintained an anti-inflammatory state, macrophage trajectories showed a gradual progression toward inflammation. Subsequently, we confirmed that cytokine- and chemokine-related signaling pathways were emphasized in macrophages. Within the CXCL signaling pathway, the increased expression of CXCL1 in macrophages can interact with CXCR2 in neutrophils, potentially inducing macrophage infiltration, stimulating neutrophil chemotaxis, and leading to an inflammatory response and cellular damage.

Conclusion

In conclusion, we firstly revealed the transcriptional signatures of macrophages in ICP and discovered a tendency toward an inflammatory state. This study also provides new evidence that the CXCL1-CXCR2 axis may play an important role in the pathogenesis of ICP.

Immunologic insights in recurrent spontaneous abortion: Molecular mechanisms and therapeutic interventions

Recurrent spontaneous abortion refers to the occurrence of two or more spontaneous abortions before or during the early stages of pregnancy. The immune system plays a crucial role in the maintenance of pregnancy and embryo implantation. Various immune cells, cytokines, and immune regulatory pathways are involved in the complex immune balance required for a stable pregnancy. Studies suggest that immune abnormalities may be associated with some recurrent spontaneous abortion cases, particularly those involving the dysregulation of immune cell function, autoimmune responses, and placental immunity. In terms of treatment, interventions targeting immune mechanisms are crucial. Various therapeutic approaches, including immunomodulatory drugs, immunoadsorption therapies, and immunocellular therapies, are continually being researched and developed. These approaches aim to restore the immune balance, enhance the success rate of pregnancies, and provide more effective treatment options for patients with recurrent spontaneous abortion.

Gravidity influences distinct transcriptional profiles of maternal and fetal placental macrophages at term

Introduction

Maternal intervillous monocytes (MIMs) and fetal Hofbauer cells (HBCs) are myeloid-derived immune cells at the maternal-fetal interface. Maternal reproductive history is associated with differential risk of pregnancy complications. The molecular phenotypes and roles of these distinct monocyte/macrophage populations and the influence of gravidity on these phenotypes has not been systematically investigated.

Methods

Here, we used RNA sequencing to study the transcriptional profiles of MIMs and HBCs in normal term pregnancies.

Results

Our analyses revealed distinct transcriptomes of MIMs and HBCs. Genes involved in differentiation and cell organization pathways were more highly expressed in MIMs vs. HBCs. In contrast, HBCs had higher expression of genes involved in inflammatory responses and cell surface receptor signaling. Maternal gravidity influenced monocyte programming, as expression of pro-inflammatory molecules was significantly higher in MIMs from multigravidae compared to primigravidae. In HBCs, multigravidae displayed enrichment of gene pathways involved in cell-cell signaling and differentiation.

Discussion

Our results demonstrated that MIMs and HBCs have highly divergent transcriptional signatures, reflecting their distinct origins, locations, functions, and roles in inflammatory responses. Furthermore, maternal gravidity influences the gene signatures of MIMs and HBCs, potentially modulating the interplay between tolerance and trained immunity. The phenomenon of reproductive immune memory may play a novel role in the differential susceptibility of primigravidae to pregnancy complications.

Preterm birth, a consequence of immune deviation mediated hyperinflammation

Preterm birth represents a multifaceted syndrome with intricacies still present in our comprehension of its etiology. In the context of a semi-allograft, the prosperity from implantation to pregnancy to delivery hinges on the establishment of a favorable maternal-fetal immune microenvironment and a successful trilogy of immune activation, immune tolerance and then immune activation transitions. The occurrence of spontaneous preterm birth could be related to abnormalities within the immune trilogy, stemming from deviation in maternal and fetal immunity. These immune deviations, characterized by insufficient immune tolerance and early immune activation, ultimately culminated in an unsustainable pregnancy. In this review, we accentuated the role of both innate and adaptive immune reason in promoting spontaneous preterm birth, reviewed the risk of preterm birth from vaginal microbiome mediated by immune changes and the potential of vaginal microbiomes and metabolites as a new predictive marker, and discuss the changes in the role of progesterone and its interaction with immune cells in a preterm birth population. Our objective was to contribute to the growing body of knowledge in the field, shedding light on the immunologic reason of spontaneous preterm birth and effective biomarkers for early prediction, providing a roadmap for forthcoming investigations.

Distinct transcriptional profiles of maternal and fetal placental macrophages at term are associated with gravidity

Maternal intervillous monocytes (MIMs) and fetal Hofbauer cells (HBCs) are myeloid-derived immune cells at the maternal-fetal interface. Little is known regarding the molecular phenotypes and roles of these distinct monocyte/macrophage populations. Here, we used RNA sequencing to investigate the transcriptional profiles of MIMs and HBCs in six normal term pregnancies. Our analyses revealed distinct transcriptomes of MIMs and HBCs. Genes involved in differentiation and cell organization pathways were more highly expressed in MIMs vs. HBCs. In contrast, HBCs had higher expression of genes involved in inflammatory responses and cell surface receptor signaling. Maternal gravidity influenced monocyte programming, as expression of pro-inflammatory molecules was significantly higher in MIMs from multigravidas compared to primigravidas. In HBCs, multigravidas displayed enrichment of gene pathways involved in cell-cell signaling and differentiation. In summary, our results demonstrated that MIMs and HBCs have highly divergent transcriptional signatures, reflecting their distinct origins, locations, functions, and roles in inflammatory responses. Our data further suggested that maternal gravidity influences the gene signatures of MIMs and HBCs, potentially modulating the interplay between tolerance and trained immunity. The phenomenon of reproductive immune memory may play a novel role in the differential susceptibility of primigravidas to pregnancy complications.

Fetal-maternal interactions during pregnancy: a 'three-in-one' perspective

A successful human pregnancy requires the maternal immune system to recognize and tolerate the semi-allogeneic fetus, allowing for appropriate trophoblasts invasion and protecting the fetus from invading pathogens. Therefore, maternal immunity is critical for the establishment and maintenance of pregnancy, especially at the maternal-fetal interface. Anatomically, the maternal-fetal interface has both maternally- and fetally- derived cells, including fetal originated trophoblasts and maternal derived immune cells and stromal cells. Besides, a commensal microbiota in the uterus was supposed to aid the unique immunity in pregnancy. The appropriate crosstalk between fetal derived and maternal originated cells and uterine microbiota are critical for normal pregnancy. Dysfunctional maternal-fetal interactions might be associated with the development of pregnancy complications. This review elaborates the latest knowledge on the interactions between trophoblasts and decidual immune cells, highlighting their critical roles in maternal-fetal tolerance and pregnancy development. We also characterize the role of commensal bacteria in promoting pregnancy progression. Furthermore, this review may provide new thought on future basic research and the development of clinical applications for pregnancy complications.

Downregulation of miR-455-3p in decidual cells promotes macrophage polarization and suppresses trophoblasts invasion

Preeclampsia (PE) is a common complication of pregnancy, usually accompanied by symptoms such as hypertension and proteinuria. It can induce severe conditions that may result in maternal and fetal morbidity and fatality. In this study, we use bioinformatics analysis to compare microRNA microassay in decidual stromal cells from PE patients and healthy donors. Our result indicated that placentas from PE patients had a higher CCL1/CXCL2 expression, compared with those from healthy donors. Bioinformatics analysis confirmed that decidual stromal cells derived from PE patients expressed significantly lower miR-455-3p than those derived from healthy donors. Transfection of miR-455-3p inhibitors enhanced the CCL2/CXCL8 expression in decidual stromal cells, and luciferase activity assay confirmed that nuclear factor of activated T cells 5 (NFAT5) mRNA was the direct target of miR-455-3p; NFAT5 also promoted cytokine secretion. In the flow cytometry study, higher M1 macrophage infiltration was observed in placentas from PE patients than in those from healthy donors. We also observed that condition medium (CM) derived from decidual stromal cells could significantly promote M1 polarization of macrophages after transfection with miR-455-3p inhibitor; further, transwell invasion assay confirmed that decidual stromal cells-CM educated macrophages suppressed trophoblast invasion. Taken together, our result demonstrates that downregulation of miR-455-3p in decidual stromal cells can promote macrophage polarization and suppress trophoblasts invasion.

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.

Postpartum hepatitis and host immunity in pregnant women with chronic HBV infection

In order to develop immune tolerant to the fetal, maternal immune system will have some modification comparing to the time before pregnancy. Immune tolerance starts and develops at the maternal placental interface. In innate immunity, decidual natural killer (dNK) cells, macrophages and dendritic cells play a key role in immue tolerance. In adaptive immunity, a moderate increase of number and immune inhibition function of regulatory T cells (Treg) are essential for immune tolerance. The trophoblast cells and immune cells expressing indoleamine 2,3-dioxygenase (IDO), the trophoblast cells expressing HLA-G, and Th1/Th2 shifting to Th2 dominant and Th17/Treg shifting to Treg domiant are in favor of maternal fetal immune tolerance. Steroids (estrogen and progesterone) and human chorionic gonadotropin (HCG) also participate in immune tolerance by inducing Treg cells or upregulating immunosuppressive cytokines. Most of the patients with chronic HBV infection are in the "HBV immune tolerance period" before pregnancy, and the liver disease is relatively stable during pregnancy. In chronic HBV infection women, after delivery, the relative immunosuppression in vivo is reversed, and Th1 is dominant in Th1/Th2 and Th17 is dominant in Th17/Treg balance. After delivery, the number of Treg decrease and NK cells increase in quantity and cytotoxicity in peripheral blood. Liver NK cells may cause liver inflammation through a non-antigen specific mechanism. After delivery, the number of CD8+ T cells will increase and HBV specific T cell response recovers from the disfunction in pregnancy. Under the background of postpartum inflammation, the rapid decrease of cortisol after delivery, and especially the enhancement of HBV specific T cell response induced by HBV DNA and cytokines, are the main reasons for postpartum hepatitis. HBeAg positive, especially HBeAg<700 S/CO, and HBV DNA>3-5Log10IU/ml are risk factors for postpartum hepatitis. Antiviral treatment in late pregnancy can reduce the incidence of mother to child transmission (MTCT) in chronic HBV infection women. Chronic HBV infection women have hepatitis both during pregnancy and more often in 12 weeks postpartum. It is generally agreed that postpartum hepatitis is mild symptoms and self-limited. Delaying drug withdrawal to 48 weeks can increase the seroconversion rate of HBeAg in delivery women with elevated alanine aminotransferase (ALT) in pregnancy.

Immunophenotyping of peripheral blood monocytes could help identify a baseline pro-inflammatory profile in women with recurrent reproductive failure

Recurrent pregnancy loss (RPL) and recurrent implantation failure (RIF) are two well-defined clinical entities, but the role of the monocytes in their pathophysiology needs to be clarified. This study aimed to evaluate the role of the three monocyte subsets (classical, intermediate, and non-classical) and relevant cytokines/chemokines in a cohort of RPL and RIF women to better characterize a baseline proinflammatory profile that could define inflammatory pathophysiology in these two different conditions. We evaluated 108 non-pregnant women: 53 RPL, 24 RIF, and 31 fertile healthy controls (HC). Multiparametric flow cytometry was used to quantify the frequency of surface chemokine receptors (CCR2, CCR5, and CX3CR1) on the monocyte subsets. Cytokines were assessed in plasma samples using a multiplex assay. The CX3CR1⁺ and CCR5⁺ intermediate monocytes were significantly higher in RPL and RIF compared to HC. A significant positive correlation was observed between CX3CR1⁺ intermediate monocytes and IL-17A (P = .03, r = 0.43). The Boruta algorithm followed by a multivariate logistic regression model was used to select the most relevant variables that could help define RPL and RIF: in RPL were CX3CR1 non-classical monocytes, TGF-β1, and CCR5 intermediate monocytes; in RIF: CCR5 intermediate monocytes and TGF-β3. The combination of these variables could predict RPL and RIF with 90 % and 82 %, respectively. Our study suggests that a combination of specific blood monocyte subsets and cytokines could aid in identifying RPL and RIF women with a pro-inflammatory profile. These findings could provide a more integrated understanding of these pathologies. Further investigation and validation in independent cohorts are warranted.

The pathophysiological mechanisms of COVID-19 and host immunity, with emphasis on the dysbiosis of the lung and gut microbiomes and pregnancy

The coronavirus 2019 (COVID-19) pandemic is a health and economic crisis. It has also highlighted human relational problems, such as racism and conflicts between nations. Although vaccination programs against the severe respiratory syndrome coronavirus 2 (SARS-CoV-2) have started worldwide, the pandemic is ongoing, and people are struggling. The mechanism of disease severity in COVID-19 is multifactorial, complicated, and affected by viral pathogenesis. For example, monocyte dysfunction due to aging and respiratory and gut dysbiosis influence the host's immunity against SARS-CoV-2 including helper T-cell imbalance and viral clearance reduction, leading to accelerated disease progression in older patients or those with underlying diseases. The different immune responses against SARS-CoV-2 also contribute to various radiological findings, including that of acute respiratory distress syndrome, which is associated with high mortality, especially in patients susceptible to disease progression. We aimed to review the pathophysiological mechanisms involved in COVID-19, with emphasis on the altered microbiome in the lung and gut, and the different radiological findings in different patient groups, such as younger adults and pregnant women.

Development and validation of a transcriptomic signature-based model as the predictive, preventive, and personalized medical strategy for preterm birth within 7 days in threatened preterm labor women

Preterm birth (PTB) is the leading cause of neonatal death. The essential strategy to prevent PTB is the accurate identification of threatened preterm labor (TPTL) women who will have PTB in a short time (< 7 days). Here, we aim to propose a clinical model to contribute to the effective prediction, precise prevention, and personalized medical treatment for PTB < 7 days in TPTL women through bioinformatics analysis and prospective cohort studies. In this study, the 1090 key genes involved in PTB < 7 days in the peripheral blood of TPTL women were ascertained using WGCNA. Based on this, the biological basis of immune-inflammatory activation (e.g., IFNγ and TNFα signaling) as well as immune cell disorders (e.g., monocytes and Th17 cells) in PTB < 7 days were revealed. Then, four core genes (JOSD1, IDNK, ZMYM3, and IL1B) that best represent their transcriptomic characteristics were screened by SVM and LASSO algorithm. Therefore, a prediction model with an AUC of 0.907 was constructed, which was validated in a larger population (AUC = 0.783). Moreover, the predictive value (AUC = 0.957) and clinical feasibility of this model were verified through the clinical prospective cohort we established. In conclusion, in the context of Predictive, Preventive, and Personalized Medicine (3PM), we have developed and validated a model to predict PTB < 7 days in TPTL women. This is promising to greatly improve the accuracy of clinical prediction, which would facilitate the personalized management of TPTL women to precisely prevent PTB < 7 days and improve maternal-fetal outcomes.

The association between chronic deciduitis and preeclampsia

Chronic deciduitis (CD) is slight inflammation of the decidua found during pregnancy. The cause of preeclampsia is thought to be placental hypoplasia, and various theories have been proposed to explain the detailed mechanism; however, its association with decidual inflammation is unclear. A retrospective case control study was conducted in a single university. Subjects were cases who delivered by cesarean section between January 1, 2013 and June 30, 2020 and whose placentas were pathological assessed. CD was diagnosed by CD138 immunostaining of placental decidua tissue, and the perinatal prognosis and incidences of hypertensive disorder of pregnancy and preeclmpsia were examined according to the presence or absence of CD. A logistic regression analysis was performed to evaluate the association between preeclampsia and 11 explanatory variables (10 patient or perinatal background factors and CD). The study population included 76 patients (non-CD, n = 54; CD, n = 22). The rate of preeclampsia was significantly higher in the CD group (P = 0.0006). Patients with CD gave birth at a significantly earlier gestational age (P=0.040) with a lower birth weight (P = 0.001), and a higher rate of LFD (P = 0.005). The Apgar scores at 1 and 5 min and umbilical artery pH were lower (P = 0.0003, 0.021 and 0.002, respectively) in the CD group. The logistic regression analysis revealed that CD was positively associated with preeclampsia. A retrospective examination of the placenta found that patients with CD had a significantly higher incidence of preeclampsia and CD is considered to be a factor that is associated with poor perinatal outcomes.

Understanding human immunity in idiopathic recurrent pregnancy loss

Miscarriage, defined as the loss of a pregnancy before a viable gestation, affects 1 in 6 couples. Recurrent pregnancy loss (RPL), defined as two or more miscarriages, affects up to 1.9% of couples. The physical, psychological, and financial impact of miscarriage can be substantial. However, despite its multifactorial etiology, for up to 50% of couples a reason behind this condition cannot be identified, termed 'idiopathic RPL'. Much recent research has strived to understand this, with immune dysregulation being a source of particular interest. In this short review we summarize the current evidence on the complex role of the immune system both pre- and early post-conception in RPL. A key question is whether systemic peripheral blood markers, in particular natural killer cell and T cells, may be utilized to accurately predict and/ or diagnose those pregnancies at high risk of loss. Given the invasive nature of endometrial testing, identification of reliable peripheral immune biomarkers is particularly appealing. Clinical trials using potent immunomodulatory agents, including intravenous immunoglobulin, donor leukocyte immunization, and tumor necrosis factor (TNF)-α inhibitors, have been undertaken with the primary objective of preventing miscarriage in women with RPL. Standardisation of both diagnostic and prognostic immune cell testing assays is required to permit accurate identification of those women who may benefit from immunomodulation. Prompt clarification is required to meet the increasing expectation from couples and clinicians, as without these advancements women are at risk of exposure to potent immune-therapies and subsequent studies are at risk of failure, generating further controversy regarding the role of immune dysregulation in women with RPL. Through this review we highlight clear gaps in our current knowledge on immune activity in RPL.

Uncomplicated oocyte donation pregnancies display an elevated CD163-positive type 2 macrophage load in the decidua, which is associated with fetal-maternal HLA mismatches

PROBLEM

The embryo of an oocyte donation (OD) pregnancy is completely allogeneic to the mother, which may challenge the maternal immune system to tolerize the fetus. Decidual macrophages are essential in maintaining a healthy pregnancy, and type 2 macrophages may exhibit immune suppressive activity. We hypothesized that the composition of decidual macrophages is different between uncomplicated OD pregnancies and non-OD in vitro fertilization (IVF) pregnancies, and is related to fetal-maternal incompatibility.

METHOD OF STUDY

Women with uncomplicated pregnancy were enrolled: 25 singleton OD pregnancies and 17 non-OD IVF pregnancies. The extent of immunohistochemical staining of CD14 (pan-macrophage marker) and CD163 (type 2 macrophage marker) in both decidua basalis and parietalis was quantitated by digital image analysis. Maternal and fetal DNA was typed for human leukocyte antigen (HLA)-A, -B, C, -DRB1, and -DQB1, and fetal-maternal HLA mismatches were calculated.

RESULTS

OD pregnancies showed a higher percentage of CD163+ staining (P = .040) and higher CD163/CD14 ratio (P = .032) in the parietalis than non-OD IVF. The OD group was separated into a semi-allogeneic group (≤5 fetal maternal HLA mismatches) and a fully allogeneic group (> 5 mismatches). The HLA-fully-allogeneic OD group, but not the HLA-semi-allogeneic OD group, showed significantly elevated CD163/CD14 ratio in the parietalis compared with the non-OD IVF group (P < .05).

CONCLUSIONS

Uncomplicated OD pregnancies display a higher CD163-positive cell fraction in the total decidual macrophage population compared to autologous pregnancies, which may suggest that a local type 2 macrophage-related mechanism is needed to compensate for the higher fetal-maternal HLA mismatch load.

Adversity in early life and pregnancy are immunologically distinct from total life adversity: macrophage-associated phenotypes in women exposed to interpersonal violence

Early childhood and pregnancy are two sensitive periods of heightened immune plasticity, when exposure to adversity may disproportionately increase health risks. However, we need deeper phenotyping to disentangle the impact of adversity during sensitive periods from that across the total lifespan. This study examined whether retrospective reports of adversity during childhood or pregnancy were associated with inflammatory imbalance, in an ethnically diverse cohort of 53 low-income women seeking family-based trauma treatment following exposure to interpersonal violence. Structured interviews assessed early life adversity (trauma exposure ≤ age 5), pregnancy adversity, and total lifetime adversity. Blood serum was assayed for pro-inflammatory (TNF-a, IL-1ß, IL-6, and CRP) and anti-inflammatory (IL-1RA, IL-4, and IL-10) cytokines. CD14+ monocytes were isolated in a subsample (n = 42) and gene expression assayed by RNA sequencing (Illumina HiSeq 4000; TruSeq cDNA library). The primary outcome was a macrophage-associated M1/M2 gene expression phenotype. To evaluate sensitivity and specificity, we contrasted M1/M2 gene expression with a second, clinically-validated macrophage-associated immunosuppressive phenotype (endotoxin tolerance) and with pro-inflammatory and anti-inflammatory cytokine levels. Adjusting for demographics, socioeconomic status, and psychopathology, higher adversity in early life (ß = .337, p = 0.029) and pregnancy (ß = .332, p = 0.032) were each associated with higher M1/M2 gene expression, whereas higher lifetime adversity (ß = -.341, p = 0.031) was associated with lower immunosuppressive gene expression. Adversity during sensitive periods was uniquely associated with M1/M2 imbalance, among low-income women with interpersonal violence exposure. Given that M1/M2 imbalance is found in sepsis, severe COVID-19 and myriad chronic diseases, these findings implicate novel immune mechanisms underlying the impact of adversity on health.

Identification of the correlations between interleukin-27 (IL-27) and immune-inflammatory imbalance in preterm birth

Preterm birth (PTB) is an immune-inflammatory disease that needs to be resolved. This study aimed to identify the role of interleukin-27 (IL-27), an immunomodulatory factor, in PTB and its associated mechanisms. Here, we analyzed the high-throughput of samples data from the maternal-fetal interface to the peripheral circulation obtained from public databases and reported that the elevated IL-27 was involved with the onset of PTB. Further bioinformatics analyses (e.g. GeneMANIA and GSEA) revealed that IL-27 overexpression in the peripheral circulation as well as maternal-fetal interface is related to the activation of the immune-inflammatory process represented by IFN-γ signaling, etc. In addition, IL-27 and immune infiltration correlation analysis demonstrated that IL-27 mediates this immune-inflammatory imbalance, plausibly mainly through monocyte-macrophage and neutrophils. This finding was further validated by analyzing additional datasets. Overall, this is the first study to elaborate on the role of IL-27-mediated immuno-inflammation in PTB from the perspective of bioinformatics, which may provide a novel strategy for the prevention and treatment of PTB.

Physiological and pathological functions of sphingolipids in pregnancy

Signaling by the bioactive sphingolipid, sphingosine 1-phosphate (S1P), and its precursors are emerging areas in pregnancy research. S1P and ceramide levels increase towards end of gestation, suggesting a physiological role in parturition. However, high levels of circulating S1P and ceramide are correlated with pregnancy disorders such as preeclampsia, gestational diabetes mellitus and intrauterine growth restriction. Expression of placental and decidual enzymes that metabolize S1P and S1P receptors are also dysregulated during pregnancy complications. In this review, we provide an in-depth examination of the signaling mechanism of S1P and ceramide in various reproductive tissues during gestation. These factors determine implantation and early pregnancy success by modulating corpus luteum function from progesterone production to luteolysis through to apoptosis. We also highlight the role of S1P through receptor signaling in inducing decidualization and angiogenesis in the decidua, as well as regulating extravillous trophoblast migration to anchor the placenta into the uterine wall. Recent advances on the role of the S1P:ceramide rheostat in controlling the fate of villous trophoblasts and the role of S1P as a negative regulator of trophoblast syncytialization to a multinucleated placental barrier are discussed. This review also explores the role of S1P in anti-inflammatory and pro-inflammatory signaling, its role as a vasoconstrictor, and the effects of S1P metabolizing enzymes and receptors in pregnancy.

Aerobic Vaginitis Induced by Escherichia coli Infection During Pregnancy Can Result in Adverse Pregnancy Outcomes Through the IL-4/JAK-1/STAT-6 Pathway

Aerobic vaginitis (AV) can occur if normal vaginal microflora are dominated by aerobic bacteria, seriously affects not only female health, but also fetal health while they are pregnant. Besides, pregnant status also aggravates the symptoms and consequences of the infection. Here, we infected pregnant BALB/c mice with Escherichia coli on embryonic day 4.5 (E4.5) (study group), and administered an equivalent volume of phosphate-buffered saline in another cohort of pregnant mice (control group). We recorded the weight of pregnant mice and their fetuses. The maternal and fetal weight of the study group decreased in comparison with that of the control group, whereas the weight of placenta increased in the study group. Then, five genes with significant upregulation and 15 genes with downregulation were screened. Expression of interleukin 4 (IL-4) mRNA in the study group decreased to 18.5%. Enzyme-linked immunosorbent assay results showed IL-4 expression in mouse plasma declined in the study group at E11.5 and E18.5. mRNA expression of chemokine (c-c motif) ligand (CCL)-17, CCL-22, CCL-24, IL-4, Janus Kinase (JAK)-1, signal transducer and activator of transcription (STAT)-6, and GATA-3 showed significant downregulation in placental and uterine tissues. Flow cytometry of primary decidual macrophages (DMs) revealed more M1-like macrophages in the study group. And after addition of IL-4 to DMs, more M1 macrophages polarized to M2 type macrophages. We did not discover bacteria existed in mouse placentas. Our study affords a feasible method for exploring and managing AV during pregnancy.

Low-intensity physical activity may protect pregnant women against spontaneous preterm labour: a prospective case-control study

The innate immune system plays a significant role in onset of parturition. Maternal antenatal physical activity can influence immune function and timing of labour. We examined physical activity patterns and concentration of 19 cytokines at 16 and 27 weeks gestational age (GA), in peripheral plasma of 28 asymptomatic women who later had spontaneous preterm labour (SPTL, <37 weeks GA) and 52 women who later delivered at term (TL; ≥37 weeks GA). This nested case-control study used data from the Ontario Birth Study cohort. Exercise was assessed using the International Physical Activity Questionnaire, and cytokines were analyzed using Luminex assays. There was no significant difference in exercise patterns between SPTL and TL subjects. Plasma concentration of interleukin (IL)-10 was significantly higher in SPTL women at 16 and 27 weeks, while tumour necrosis factor alpha (TNF-α), IL-8, and monocyte chemoattractant protein (MCP)-1 concentrations were increased at 27 weeks GA (p < 0.05). Concentration of IL-10 was negatively correlated with the amount of reported walking (ρ = −0.264, p = 0.03). Women should be encouraged to partake in low-intensity exercise throughout pregnancy, as it may confer a protective effect against SPTL through IL-10–mediated pathways. Additionally, plasma cytokine analysis at 27 weeks GA may be useful for predicting SPTL in asymptomatic women.

Novelty: In women that delivered preterm, plasma levels of anti-inflammatory cytokine IL-10 were significantly elevated at 16 and 27 weeks of gestation. Plasma levels of IL-10 were negatively correlated with the amount of reported walking. Concentration of IL-8, MCP-1 and TNF-α were increased in plasma of asymptomatic women that subsequently deliver preterm.

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.

Single-cell profiling of the human decidual immune microenvironment in patients with recurrent pregnancy loss

Maintaining homeostasis of the decidual immune microenvironment at the maternal–fetal interface is essential for placentation and reproductive success. Although distinct decidual immune cell subpopulations have been identified under normal conditions, systematic understanding of the spectrum and heterogeneity of leukocytes under recurrent miscarriage in human deciduas remains unclear. To address this, we profiled the respective transcriptomes of 18,646 primary human decidual immune cells isolated from patients with recurrent pregnancy loss (RPL) and healthy controls at single-cell resolution. We discovered dramatic differential distributions of immune cell subsets in RPL patients compared with the normal decidual immune microenvironment. Furthermore, we found a subset of decidual natural killer (NK) cells that support embryo growth were diminished in proportion due to abnormal NK cell development in RPL patients. We also elucidated the altered cellular interactions between the decidual immune cell subsets in the microenvironment and those of the immune cells with stromal cells and extravillous trophoblast under disease state. These results provided deeper insights into the RPL decidual immune microenvironment disorder that are potentially applicable to improve the diagnosis and therapeutics of this disease.

Transcriptomic Profiling of Human Placenta in Gestational Diabetes Mellitus at the Single-Cell Level

Gestational diabetes mellitus (GDM) is associated with an increased risk of adverse pregnancy outcomes. Increasing evidence shows that placentation defects may play important roles in GDM. However, our understanding of the human placenta remains limited. In this study, we generated a comprehensive transcriptomic profile of cellular signatures and transcriptomes in the human placenta in GDM using single-cell RNA sequencing (scRNA-seq), constructed a comprehensive cell atlas, and identified cell subtypes and subtype-specific marker genes. In addition, we investigated the placental cellular function and intercellular interactions in GDM. These findings help to elucidate the molecular mechanisms of GDM, and may facilitate the development of new approaches to GDM treatment and prevention.

Tumor necrosis factor receptor type 1-associated death domain (TRADD) regulates epithelial-mesenchymal transition (EMT), M1/M2 macrophage polarization and ectopic endometrial cysts formation in endometriosis

Background

Endometriosis is a gynecological non-malignant disease that is manifested by the presence of extrauterine ectopic endometrial cells and stroma. The aim of current study was to explore the role of tumor necrosis factor receptor type 1-associated death domain (TRADD) protein in endometriosis.

Methods

Cell migration, invasion, and the expression of epithelial-mesenchymal transition (EMT) inducers in TRADD silencing or overexpression in eutopic endometrial stromal cells (EuSCs) and ectopic endometrial stromal cells (EcSCs) were analyzed by wound healing assay, transwell assay, quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blotting and rat endometriosis model. A cell line derived from THP-1 macrophages was used to measure M1/M2 polarization in endometriosis by flow cytometry and enzyme-linked immunosorbent assay (ELISA).

Results

The mRNA level and protein expression of TRADD, keratin, E-cadherin, N-cadherin, vascular endothelial growth factor, matrix metalloproteinase-9, CD40, and CD206 were abnormally expressed in ectopic endometrial tissues and EcSCs. TRADD silencing promoted migration, invasion, and EMT in EuSCs, while TRADD overexpression restrained migration, invasion, and EMT in EcSCs. TRADD knockdown prohibited M1/M2 polarization in normal endometrial homogenization-treated THP-1-derived macrophages, whereas TRADD upregulation facilitated M1/M2 polarization in patients with endometrial homogenization-treated THP-1-derived macrophages. In addition, TRADD overexpression suppressed ectopic endometrial cysts formation in a rat endometriosis model. TRADD overexpression activated NF-κB and MAPK signaling in EcSCs and rat models.

Conclusions

Our results indicated that the overexpression of TRADD prohibited migration, invasion, EMT, M1/M2 polarization and ectopic endometrial cysts formation in endometriosis, and this might due to regulating NF-κB and MAPK signaling.

Maternal Immunological Adaptation During Normal Pregnancy

The risk and severity of specific infections are increased during pregnancy due to a combination of physiological and immunological changes. Characterizing the maternal immune system during pregnancy is important to understand how the maternal immune system maintains tolerance towards the allogeneic fetus. This may also inform strategies to prevent maternal fatalities due to infections and optimize maternal vaccination to best protect the mother-fetus dyad and the infant after birth. In this review, we describe what is known about the immunological changes that occur during a normal pregnancy.

Mechanisms and evidence of vertical transmission of infections in pregnancy including SARS-CoV-2s

There remain unanswered questions concerning mother‐to‐child‐transmission of SARS‐CoV‐2. Despite reports of neonatal COVID‐19, SARS‐CoV‐2 has not been consistently isolated in perinatal samples, thus definitive proof of transplacental infection is still lacking. To address these questions, we assessed investigative tools used to confirm maternal‐fetal infection and known protective mechanisms of the placental barrier that prevent transplacental pathogen migration. Forty studies of COVID‐19 pregnancies reviewed suggest a lack of consensus on diagnostic strategy for congenital infection. Although real‐time polymerase chain reaction of neonatal swabs was universally performed, a wide range of clinical samples was screened including vaginal secretions (22.5%), amniotic fluid (35%), breast milk (22.5%) and umbilical cord blood. Neonatal COVID‐19 was reported in eight studies, two of which were based on the detection of SARS‐CoV‐2 IgM in neonatal blood. Histological examination demonstrated sparse viral particles, vascular malperfusion and inflammation in the placenta from pregnant women with COVID‐19. The paucity of placental co‐expression of ACE‐2 and TMPRSS2, two receptors involved in cytoplasmic entry of SARS‐CoV‐2, may explain its relative insensitivity to transplacental infection. Viral interactions may utilise membrane receptors other than ACE‐2 thus, tissue susceptibility may be broader than currently known. Further spatial‐temporal studies are needed to determine the true potential for transplacental migration.

Got your mother in a whirl: The role of maternal T cells and myeloid cells in pregnancy

Appropriate development of the placenta is required for healthy pregnancy to occur. After implantation of the fertilized blastocyst, fetal trophoblasts invade the endometrium and myometrium of the mother's uterus to establish placentation. In this process, fetal trophoblasts encounter maternal immune cells. In this review, we focus on the role of maternal T cells and myeloid cells (macrophages, dendritic cells) in pregnancy and their interaction with trophoblasts. To retain immunologic tolerization, trophoblasts evade immune recognition by T cells and produce factors that modulate their phenotype and function. On top of that, the local environment at the maternal-fetal interface favors expansion of regulatory T cells. Macrophages and dendritic cells are essential in maintaining a healthy pregnancy. They produce soluble factors and act as antigen-presenting cells, thereby interacting with T cells. Herein, M2 macrophages, immature dendritic cells, CD4⁺ Th2 cells, and regulatory T cells represent an axis that maintains a local immune tolerant environment. We consider outstanding issues concerning these cell types and their pathways, which need to be addressed in future investigations. Data from recent single-cell sequencing experiments of the placental bed, to study heterogeneity of maternal immune cells and to predict cell-cell interactions, are discussed. Novel ways for long-term culturing of primary trophoblasts allow for cell-cell interaction studies in a functional way. Future directions should include study of the functionality of currently known and newly identified decidual immune cell subsets in healthy and complicated pregnancies, and their interaction with and modulation by trophoblast cells.

Reprint of: Myometrial activation: Novel concepts underlying labor

Term labour is a state of physiological inflammation orchestrated by multiple uterine tissues (both fetal and maternal). This physiological inflammation preceding and accompanying labour onset is characterized by an increase in cytokine and chemokine secretion by the fetal membranes, as well as uterine tissues (i.e., decidua and myometrium). Pro-inflammatory cytokines and chemokines activate circulating maternal peripheral leukocytes as well as the uterine vascular endothelium to permit leukocyte infiltration into the uterus. This inflammatory milieu, in the absence of infection, is required for the initiation of labour as the uterine-infiltrated leukocytes secrete matrix metalloproteinases to induce fetal membrane rupture and cervical ripening as well as various labour mediators, which promote contractions of the myometrium. Myometrial activation at term and the onset of labour contractions are directly related to the changes in the ovarian/placental hormone progesterone and its downstream mediators (i.e., the progesterone receptors, PRA/B), which are also critical for maintenance of pregnancy. Our recent data provides direct evidence in support of local and functional P4 withdrawal in the uterine muscle (myometrium) via the activator protein-1 (AP-1) mediated pathway. This review outlines known mechanisms regulating activation of human labour, including progesterone and cytokine signaling. Understanding of the molecular mechanism of myometrial activation and labour onset could facilitate the development of new therapeutics for high-risk pregnant women to prevent premature uterine activation and preterm birth.

Probiotics with ameliorating effects on the severity of skin inflammation in psoriasis: Evidence from experimental and clinical studies

Experimental and clinical studies have confirmed safety and the medical benefits of probiotics as immunomodulatory medications. Recent advances have emphasized the critical effect of gastrointestinal bacteria in the pathology of inflammatory disorders, even, outside the gut. Probiotics have shown promising results for curing skin-influencing inflammatory disorders through modulating the immune response by manipulating the gut microbiome. Psoriasis is a complex inflammatory skin disease, which exhibits a microbiome distinct from the normal skin. In the present review, we considered the impact of gastrointestinal microbiota on the psoriasis pathogenesis, and through literature survey, attempted to explore probiotic species utilized for psoriasis treatment.

Myometrial activation: Novel concepts underlying labor

Term labour is a state of physiological inflammation orchestrated by multiple uterine tissues (both fetal and maternal). This physiological inflammation preceding and accompanying labour onset is characterized by an increase in cytokine and chemokine secretion by the fetal membranes, as well as uterine tissues (i.e., decidua and myometrium). Pro-inflammatory cytokines and chemokines activate circulating maternal peripheral leukocytes as well as the uterine vascular endothelium to permit leukocyte infiltration into the uterus. This inflammatory milieu, in the absence of infection, is required for the initiation of labour as the uterine-infiltrated leukocytes secrete matrix metalloproteinases to induce fetal membrane rupture and cervical ripening as well as various labour mediators, which promote contractions of the myometrium. Myometrial activation at term and the onset of labour contractions are directly related to the changes in the ovarian/placental hormone progesterone and its downstream mediators (i.e., the progesterone receptors, PRA/B), which are also critical for maintenance of pregnancy. Our recent data provides direct evidence in support of local and functional P4 withdrawal in the uterine muscle (myometrium) via the activator protein-1 (AP-1) mediated pathway. This review outlines known mechanisms regulating activation of human labour, including progesterone and cytokine signaling. Understanding of the molecular mechanism of myometrial activation and labour onset could facilitate the development of new therapeutics for high-risk pregnant women to prevent premature uterine activation and preterm birth.

The Role of Macrophages in Oocyte Donation Pregnancy: A Systematic Review

The embryo of an oocyte donation (OD) pregnancy is completely allogeneic to the mother, which leads to a more serious challenge for the maternal immune system to tolerize the fetus. It is thought that macrophages are essential in maintaining a healthy pregnancy, by acting in immunomodulation and spiral arterial remodeling. OD pregnancies represent an interesting model to study complex immunologic interactions between the fetus and the pregnant woman since the embryo is totally allogeneic compared to the mother. Here, we describe a narrative review on the role of macrophages and pregnancy and a systematic review was performed on the role of macrophages in OD pregnancies. Searches were made in different databases and the titles and abstracts were evaluated by three independent authors. In total, four articles were included on OD pregnancies and macrophages. Among these articles, some findings are conflicting between studies, indicating that more research is needed in this area. From current research, we could identify that there are multiple subtypes of macrophages, having diverse biological effects, and that the ratio between subtypes is altered during gestation and in aberrant pregnancy. The study of macrophages’ phenotypes and their functions in OD pregnancies might be beneficial to better understand the maternal-fetal tolerance system.

Placental Hofbauer Cell Polarization Resists Inflammatory Cues In Vitro

Feto-placental Hofbauer cells (HBCs) are macrophages residing in placental stroma. They are generally described as anti-inflammatory M2 polarized cells, promoting tolerance and tissue remodeling. In certain pathologies, however, a possible phenotypical switch towards pro-inflammatory M1 macrophages has been proposed. The study aimed to determine if HBCs can acquire an M1 phenotype under pro-inflammatory conditions in vitro. HBCs were isolated from healthy human term placentas. Cells were cultivated upon addition of LPS and INF-γ or IL-4 and IL-13 to induce the M1 and M2 phenotype, respectively. Specific cell polarization markers and cytokines, associated with respective phenotypes, were investigated by flow cytometry and ELISA. THP-1 macrophages served as positive control. Pro-inflammatory stimuli reduced M2 markers CD163 and DC-SIGN, but did not induce M1 markers. TNF-α release was increased, but at the same time TGF-β and IL-10 release was upregulated, resembling in part the M2b sub-phenotype. Anti-inflammatory stimuli had no effect on HBC polarization. HBCs maintain their M2 phenotype in vitro despite inflammatory stimuli, which might represent a state of adaption and tolerance to avoid rejection of the semiallogeneic feto-placental unit.

Unveiling the pathophysiology of gestational diabetes: Studies on local and peripheral immune cells

Gestational diabetes mellitus (GDM) has been associated with impaired maternal immune response. Our aim was to review the available literature linking immune cells profile to GDM, in order to comprehend the role that different subpopulations play in the development of this pathology. We searched in PubMed for studies published in the last decade on circulating levels and placenta expression of immune cells on GDM. We identified 18 studies with several differences regarding the study design, clinical characteristics, number of participants, cell subpopulation and type of sample. Most studies assessed only one subpopulation either in peripheral blood or placenta and did not analyse functional properties of the cells. The most frequently evaluated immune cells were T lymphocytes, especially regulatory T (Tregs), and natural killer (NK) cells in the peripheral blood, and placental macrophages. No studies analysing B cells were identified, and only one study each evaluating γδT cells, dendritic cell (DC) and monocytes was found. Although there are controversies, at least one study reported positive association between GDM and CD4⁺ (activated), Tregs, Th17 and γδT cells; neutrophil/lymphocyte; NK cell (cytotoxic); macrophages; and monocytes. The number of studies is still small, so caution should be exercised in interpreting the data, and further research is required to validate these findings and establish the role of adaptive and innate immune cells in GDM pathophysiology.

MicroRNA-transcriptome networks in whole blood and monocytes of women undergoing preterm labour

Preterm birth is attributed to neonatal morbidity as well as cognitive and physiological challenges. We have previously identified significant differences in mRNA expression in whole blood and monocytes, as well as differences in miRNA concentration in blood plasma, extracellular vesicles (EV) and EV-depleted plasma in women undergoing spontaneous preterm labour (sPTL). The goal of this analysis was to identify differences in miRNA expression within whole blood (WB) and peripheral monocytes (PM) from the same population of women undergoing sPTL compared with non-labouring controls matched by gestational age. We performed single-end small RNA sequencing in whole blood and peripheral monocytes from women undergoing sPTL with active contractions (24-34 weeks of gestation, N = 15) matched for gestational age to healthy pregnant non-labouring controls (>37 weeks gestation, N = 30) who later delivered at term as a part of the Ontario Birth Study (Toronto, Ontario CA). We identified significant differences in expression of 16 miRNAs in PMs and nine miRNAs in WB in women undergoing sPTL. In PMs, these miRNAs were predicted targets of 541 genes, including 28 previously associated with sPTL. In WB, miRNAs were predicted to target 303 genes, including nine previously associated with sPTL. These genes were involved in a variety of immune pathways, including interleukin-2 signalling. This study is the first to identify changes in miRNA expression in WB and PMs of women undergoing sPTL. Our results shed light on potential mechanisms by which miRNAs may play a role in mediating systemic inflammatory response in pregnant women that deliver prematurely.

The role of innate immunity in spontaneous preterm labor: A systematic review

BACKGROUND

Immunoinflammatory response by innate immunity components is a field with increasing interest in understanding the mechanisms behind preterm labor (PTL).

OBJECTIVES

Systematic review of the role of innate immunity in spontaneous PTL.

STUDY DESIGN

PubMed, Scopus, ClinicalTrials.gov and Web of Science were searched using pregnancy AND innate OR toll-like OR natural-killer OR dendritic AND delivery OR premature OR rupture of membranes.

MAIN OUTCOME MEASURES

All article titles and abstracts were evaluated by two individuals, based in strict predefined inclusion criteria. For relevant studies, title, abstract, and full text were assessed to identify PTL and innate immunity studies, excluding multiple pregnancies, cervical insufficiency and indicated PTL.

RESULTS

From 894 articles evaluated, 101 full texts articles were assessed independently. For this systematic review 44 studies were finally included. Toll-like receptors 2 and 4 mediated immune dysfunction and inflammation can result in PTL. Moreover, PTL is linked to high levels of CD14⁺ monocytes; neutrophils seem important in inflammation-associated PTL and in pathological preterm premature rupture of membranes. Besides, decidual natural-killer cells and premature activation of dendritic cells may also participate in the etiology of PTL. Finally, dysregulation of maternal complement might increase the risk of PTL, characterized by high levels of innate lymphoid cells 2 and 3.

CONCLUSIONS

Further research is warranted to ascertain the precise role of innate immunity in PTL. Nonetheless, our results indicate that Toll-like receptors, monocytes, natural-killer cells, dendritic cells and complement have significant roles in PTL.

Immune imbalance is associated with the development of preeclampsia

Preeclampsia (PE) is characterized by hypertension and proteinuria. It affects about 5% to 8% of pregnancies and causes maternal and perinatal mortality and morbidity. The immune imbalance and excessive inflammatory response play vital roles in the pathogenesis of PE.In this study, we performed a case-control study to investigate the levels of cytokines, chemokines and adhesion molecules in serum and placenta of normal pregnant and PE women by Bio-Plex multiplex immunoassay and immunohistochemistry. In addition, we explored the phenotypes of monocyte and macrophage in peripheral blood and placentas in 2 groups by using flow cytometry analysis and immunohistochemistry.Our results show that pro-inflammatory factors, including interleukin-1β (IL-1β), IL-6, IL-7, IL-8, IL-17a, monocyte chemotactic protein 1 (MCP -1), and macrophage inflammatory protein 1β (MIP-1β) were significantly increased in serum of women with PE compared with controls. In addition, we detected that IL-1β, IL-6, and MCP-1 were also increased in placentas of women with PE. We further revealed that peripheral blood monocytes showed a pro-inflammatory M1-like phenotype in women with PE. Consistently, M1 macrophage infiltration was increased in placenta of women with PE compared to that of normal pregnant women.Our results demonstrated that immune imbalance promotes an inflammatory state during PE and it may be a potential therapeutic possibility for the management of PE.

Immune responses at the maternal-fetal interface

Pregnancy poses an immunological challenge because a genetically distinct (nonself) fetus must be supported within the pregnant female for the required gestational period. Placentation, or the establishment of the fetally derived placenta, is a common strategy used by eutherian mammals to protect the fetus and promote its growth. However, the substantial morphological differences of the placental architecture among species suggest that the process of placentation results from convergent evolution. Although there are considerable similarities in placental function across placental mammals, there are important differences that arise owing to species-specific immunological (and other biological) constraints. This Review focuses on the immunological similarities and differences that occur at the maternal-fetal interface in the context of human and mouse pregnancies. We discuss how the decidua and placenta of these different species form key immunological barriers that sustain maternal tolerance yet generate innate immune responses that prevent microbial infections.

Molecular detection of uterine innate lymphoid cells in the immunological mouse model of pregnancy loss

Innate lymphoid cells (ILCs) are newly identified members of the innate lymphocyte family, which can function as adaptive T cells and act as critical modulators of inflammatory processes within different tissues and immune diseases. The role of uterine ILCs (uILCs) has recently been elucidated alongside changes associated with normal pregnancy. However, the proportions of uterine ILCs and their role in unsuccessful pregnancy remain unclear. We analyzed the characterization of uILC subsets and the expression of signature cytokines associated with ILCs in a mouse model of unsuccessful pregnancy induced by LPS, and we describe the dynamic changes they undergo during this process. We found that mice exposed to LPS display significantly higher levels of uNK cells, and uILC3s. However, a lower proportion of uILC2s and uILC1s were detected in abortion mice. In addition, we found that abortion mice display markedly higher expression of IFN-γ and IL-A17, and lower levels of IL-5. No significant differences in the expression of IL-13 and IL-22 were observed. The findings suggest that uILCs play distinct non-redundant roles during pregnancy, and uILCs may affect maternal-fetal tolerance via IL-17A, IL-5, and IFN-γ production.

Macrophage M1/M2 polarization in patients with pregnancy-induced hypertension

This study aimed to validate whether macrophage polarization imbalance and abnormal cytokines production occurred in pregnancy-induced hypertension (PIH) patients. PIH women (n = 26) were enrolled and the level of biochemical parameters were determined. The percentage of CD86- and CD163-positive cells, representing M1 and M2 macrophages, were determined by flow cytometry. The concentrations of cytokines (TNF-α, IL-1β, IL-4, IL-13, and IL-10) were determined using enzyme-linked immunosorbent assay kit. THP-1 cells were incubated with 10% serum from PIH and control groups, and then macrophage polarization and cytokines production were analyzed. The levels of high-density lipoprotein cholesterol and apolipoprotein A1 were significantly lower, and the levels of fasting blood glucose, total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, apolipoprotein B, and lipoprotein a were significantly higher in the PIH group than that in the control group. The PIH group contained a significant higher percentage of CD86-positive cells (M1) and a significant lower percentage of CD163-positive cells (M2), representing higher M1/M2 ratio, than the control group. The PIH group expressed higher concentrations of TNF-α and IL-1β, and expressed lower concentrations of IL-4, IL-10, and IL-13 than the control group. The in vitro experiment also showed macrophage polarization imbalance and abnormal cytokines production in THP-1 cells treated with PIH serum as compared with that treated with control serum. Macrophage polarization imbalance and abnormal cytokines production occurred in PIH patients and in THP-1 cells treated with PIH serum.

The response of the innate immune and cardiovascular systems to LPS in pregnant and nonpregnant mice

Sepsis is the leading cause of direct maternal mortality, but there are no data directly comparing the response to sepsis in pregnant and nonpregnant (NP) individuals. This study uses a mouse model of sepsis to test the hypothesis that the cardiovascular response to sepsis is more marked during pregnancy. Female CD1 mice had radiotelemetry probes implanted and were time mated. NP and day 16 pregnant CD-1 mice received intraperitoneal lipopolysaccharide (LPS; 10 μg, serotype 0111: B4). In a separate study, tissue and serum (for RNA, protein and flow cytometry studies), aorta and uterine vessels (for wire myography) were collected after LPS or vehicle control administration. Administration of LPS resulted in a greater fall in blood pressure in pregnant mice compared to NP mice. This occurred with similar changes in the circulating levels of cytokines, vasoactive factors, and circulating leukocytes, but with a greater monocyte and lesser neutrophil margination in the lungs of pregnant mice. Baseline markers of cardiac dysfunction and apoptosis as well as cytokine expression were higher in pregnant mice, but the response to LPS was similar in both groups as was the ex vivo assessment of vascular function. In pregnant mice, nonfatal sepsis is associated with a more marked hypotensive response but not a greater immune response. We conclude that endotoxemia induces a more marked hypotensive response in pregnant compared to NP mice. These changes were not associated with a more marked systemic inflammatory response in pregnant mice, although monocyte lung margination was greater. The more marked hypotensive response to LPS may explain the greater vulnerability to some infections exhibited by pregnant women.

Cigarette smoke extract interferes with placenta macrophage functions: A new mechanism to compromise placenta functions?

The success of pregnancy depends on the maternal immune system's ability to promote tolerance and host defense. This equilibrium is compromised in inflammatory and infectious impairment of placenta. Smoking during pregnancy exposes the fetus to severe complications which might result from an alteration in placenta macrophages (pMφ) functions. In this study, we assessed the effect of cigarette smoke extract (CSE) on the functions of third trimester pMφs.CSE inhibited particles uptake and the formation of multinucleated giant cells, a recently reported property of pMφs based on their ability to fuse in vitro. These alterations were associated with a CSE-induced abnormal activation of pMφs, which was characterized by an increased release of TNF, interleukin (IL)-33, and decreased IL-6 and IL-10 release. Furthermore, CSE enhanced the expression of metalloproteinase genes known to be involved in tissue remodeling. This effect of CSE on pMφs was specific because CSE affected circulating monocytes in a different way. Finally, we showed that nicotine affected in part the functional properties of pMφs. Taken together, these results showed that CSE modulated the functional activity of pMφs, which may compromise pregnancy.

The impact of circulating preeclampsia-associated extracellular vesicles on the migratory activity and phenotype of THP-1 monocytic cells

Intercellular communication via extracellular vesicles (EVs) and their target cells, especially immune cells, results in functional and phenotype changes that consequently may play a significant role in various physiological states and the pathogenesis of immune-mediated disorders. Monocytes are the most prominent environment-sensing immune cells in circulation, skilled to shape their microenvironments via cytokine secretion and further differentiation. Both the circulating monocyte subset distribution and the blood plasma EV pattern are characteristic for preeclampsia, a pregnancy induced immune-mediated hypertensive disorder. We hypothesized that preeclampsia-associated EVs (PE-EVs) induced functional and phenotypic alterations of monocytes. First, we proved EV binding and uptake by THP-1 cells. Cellular origin and protein cargo of circulating PE-EVs were characterized by flow cytometry and mass spectrometry. An altered phagocytosis-associated molecular pattern was found on 12.5 K fraction of PE-EVs: an elevated CD47 "don't eat me" signal (p < 0.01) and decreased exofacial phosphatidylserine "eat-me" signal (p < 0.001) were found along with decreased uptake of these PE-EVs (p < 0.05). The 12.5 K fraction of PE-EVs induced significantly lower chemotaxis (p < 0.01) and cell motility but accelerated cell adhesion of THP-1 cells (p < 0.05). The 12.5 K fraction of PE-EVs induced altered monocyte functions suggest that circulating EVs may have a role in the pathogenesis of preeclampsia.

Comparative analysis of gene expression in maternal peripheral blood and monocytes during spontaneous preterm labor

BACKGROUND

Preterm birth is the leading cause of newborn death worldwide, and is associated with significant cognitive and physiological challenges in later life. There is a pressing need to define the mechanisms that initiate spontaneous preterm labor, and for development of novel clinical biomarkers to identify high-risk pregnancies. Most preterm birth studies utilize fetal tissues, and there is limited understanding of the transcriptional changes that occur in mothers undergoing spontaneous preterm labor. Earlier work revealed that a specific population of maternal peripheral leukocytes (macrophages/monocytes) play an active role in the initiation of labor. Thus, we hypothesized that there are dynamic gene expression changes in maternal blood leukocytes during preterm labor.

OBJECTIVE

Using next-generation sequencing we aim to characterize the transcriptome in whole blood leukocytes and peripheral monocytes of women undergoing spontaneous preterm labor compared to healthy pregnant women who subsequently delivered at full term.

STUDY DESIGN

RNA sequencing was performed in both whole blood and peripheral monocytes from women who underwent preterm labor (24-34 weeks of gestation, N = 20) matched for gestational age to healthy pregnant controls (N = 30). All participants were a part of the Ontario Birth Study cohort (Toronto, Ontario, Canada).

RESULTS

We identified significant differences in expression of 262 genes in peripheral monocytes and 184 genes in whole blood of women who were in active spontaneous preterm labor compared to pregnant women of the same gestational age not undergoing labor, with 43 of these genes differentially expressed in both whole blood and peripheral monocytes. ADAMTS2 expression was significantly increased in women actively undergoing spontaneous preterm labor, which we validated through digital droplet reverse transcriptase polymerase chain reaction. Intriguingly, we have also identified a number of gene sets including signaling by stem cell factor-KIT, nucleotide metabolism, and trans-Golgi network vesicle budding, which exhibited changes in relative gene expression that was predictive of preterm labor status in both maternal whole blood and peripheral monocytes.

CONCLUSION

This study is the first to investigate changes in both whole blood leukocytes and peripheral monocytes of women actively undergoing spontaneous preterm labor through robust transcript measurements from RNA sequencing. Our unique study design overcame confounding based on gestational age by collecting blood samples from women matched by gestational age, allowing us to study transcriptomic changes directly related to the active preterm parturition. We performed RNA profiling using whole genome sequencing, which is highly sensitive and allowed us to identify subtle changes in specific genes. ADAMTS2 expression emerged as a marker of prematurity within peripheral blood leukocytes, an accessible tissue that plays a functional role in signaling during the onset of labor. We identified changes in relative gene expression in a number of gene sets related to signaling in monocytes and whole blood of women undergoing spontaneous preterm labor compared to controls. These genes and pathways may help identify potential targets for the development of novel drugs for preterm birth prevention.

Macrophage plasticity, polarization, and function in health and disease

Macrophages are heterogeneous and their phenotype and functions are regulated by the surrounding micro-environment. Macrophages commonly exist in two distinct subsets: 1) Classically activated or M1 macrophages, which are pro-inflammatory and polarized by lipopolysaccharide (LPS) either alone or in association with Th1 cytokines such as IFN-γ, GM-CSF, and produce pro-inflammatory cytokines such as interleukin-1β (IL-1β), IL-6, IL-12, IL-23, and TNF-α; and 2) Alternatively activated or M2 macrophages, which are anti-inflammatory and immunoregulatory and polarized by Th2 cytokines such as IL-4 and IL-13 and produce anti-inflammatory cytokines such as IL-10 and TGF-β. M1 and M2 macrophages have different functions and transcriptional profiles. They have unique abilities by destroying pathogens or repair the inflammation-associated injury. It is known that M1/M2 macrophage balance polarization governs the fate of an organ in inflammation or injury. When the infection or inflammation is severe enough to affect an organ, macrophages first exhibit the M1 phenotype to release TNF-α, IL-1β, IL-12, and IL-23 against the stimulus. But, if M1 phase continues, it can cause tissue damage. Therefore, M2 macrophages secrete high amounts of IL-10 and TGF-β to suppress the inflammation, contribute to tissue repair, remodeling, vasculogenesis, and retain homeostasis. In this review, we first discuss the basic biology of macrophages including origin, differentiation and activation, tissue distribution, plasticity and polarization, migration, antigen presentation capacity, cytokine and chemokine production, metabolism, and involvement of microRNAs in macrophage polarization and function. Secondly, we discuss the protective and pathogenic role of the macrophage subsets in normal and pathological pregnancy, anti-microbial defense, anti-tumor immunity, metabolic disease and obesity, asthma and allergy, atherosclerosis, fibrosis, wound healing, and autoimmunity.